辱虐管理对员工不安全行为的U型影响——一个双调节模型

为进一步探究辱虐管理与不安全行为之间的作用关系,更好地减少生产安全事故的发生,以242名高危行业企业员工为调查对象,应用层次回归方法实证检验辱虐管理与员工不安全行为之间的曲线关系以及正念、领导-成员交换在二者之间的调节作用.研究结果表明:辱虐管理对不安全行为有U型影响;正念调节辱虐管理与不安全行为之间的关系,二者之间的...     

城市带状绿地空气负离子水平及其影响因子

以北京市西四环旁侧城市带状绿地作为研究对象,采用小尺度测定的方法,分析城市带状绿地空气负离子水平及其影响因子。结果表明：城市带状绿地空气负离子浓度的日变化与季节变化均较明显;清晨时段负离子浓度较高,中午时段空气负离子浓度较低;7月空气负离子浓度最高,12月最低;空气负离子浓度与温度分别呈显著负相关（4、7月）、显著正相关（12月）,与相对湿度呈显著正相关,与空气含菌量呈显著负相关（P〈0.05）。     

不同环境场所夏季空气负离子浓度分布特征及其与环境因子的关系

大气离子是由许多自然和人为的原因产生,并且它们的浓度在不同环境场所下差别很大。以我国南部沿海某省份作为研究区域,挑选了近10处有代表性的环境场所进行为期一周的实测和研究,收集了空气正、负离子浓度、风速、空气温度、相对湿度等数据。研究显示,空气负离子浓度与风速、水、植物、相对湿度等有较为密切的关系,其中最主要的影响因素是水,其次是风,最小的是气温。为了改善城市生态环境,建议在城市规划建设中采取有效措施以提高空气负离子浓度。     

碲化镉量子点诱导氧自由基产生的检测

随着量子点(quantum dots,QDs)在生物标记和医学影像等领域的应用日益广泛,其环境暴露量逐渐增加,深入探讨QDs的毒性机制具有重要意义。QDs通过产生活性氧(ROS)诱发毒性效应是目前普遍接受的毒作用模式。为了探讨量子点的毒性与所诱发的ROS的种类和数量的关系,选用碲化镉量子点(CdTe QDs和CdTe/ZnS QDs),利用电子顺磁共振技术(EPR)分别测定了CdTe QDs和CdTe/ZnS QDs在无细胞体系中诱导ROS产生的种类和强度;利用EPR法、紫外可见分光光度法和荧光分光光度法分别测定了4、20和100nmol·mL-1的CdTe QDs和CdTe/ZnS QDs对超氧阴离子(·O2-)和羟基自由基(·OH)产生的促进作用。实验结果显示,CdTe QDs可诱导·O2-的产生;CdTe QDs和CdTe/ZnS QDs对·OH与·O2-的产生有明显的促进作用,且具有剂量-效应关系。研究表明,量子点可诱导和促进ROS产生,不同结构量子点对ROS的诱导和促进作用不同。     

What does team–member exchange bring to the party? A meta‐analytic review of team and leader social exchange

Both leader–member exchange (LMX) and team–member exchange (TMX) measure the quality of reciprocal exchange among employees in the workplace. Although LMX focuses on supervisor–subordinate relationships while TMX examines the relationships among team members, both have theory‐based and empirically proven relations with workplace outcomes such as job performance, organizational commitment, job satisfaction, and turnover intentions. However, it is not yet known which has more of an impact on such workplace outcomes—specifically, it is not clear if an employee's time is best spent developing vertical relationships among supervisors and subordinates (LMX) or on the horizontal relationships among team members (TMX). Accordingly, this meta‐analysis explores the incremental validity and relative importance of these two social exchange‐based constructs. The theoretical logic underlying LMX and TMX is clarified, and the parameter estimates between LMX, TMX, and work outcomes are reported. Results demonstrate that TMX shows incremental validity above and beyond LMX for some outcomes (organizational commitment and job satisfaction), but not others (job performance and turnover intentions). Also, LMX shows greater relative importance across all four outcomes. In sum, the clarification of the theoretical and empirical landscape lays a foundation for recommendations for future research. Copyright © 2013 John Wiley & Sons, Ltd.     

磁性树脂对地下水中硝酸盐的去除效能及影响因素

利用小试实验研究了磁性离子交换树脂对水中硝酸盐的去除效能,并探讨了地下水中常见有机物及无机离子对其去除效能的影响.结果表明,磁性离子交换树脂对纯水中20mg/L的NO3--N的交换容量为55.91mg/mL,且去除速率较快,10min基本达到去除平衡;地下水中的腐殖酸类有机物对NO3--N的去除基本没有影响,而常见阴离子具有较明显的影响,其影响程度为SO42->CO32->Cl->HCO3-;针对徐州某水厂地下水的去除研究表明,通水倍数为500BV时磁性离子交换树脂对地下水中NO3--N的去除率约为50%左右.综上,磁性离子交换树脂可以作为去除地下水中的硝酸盐一种处理技术.     

低温胁迫对6种珍贵树种苗木光合荧光特性的影响

以格木（Erythrophleum fordii）、降香黄檀（Dalbergia odorifera）、闽楠（Phoebe bournei）檀香（Santalum album）、铁刀木（Cassia siamea）和樟树（Cinnamomum camphora）6种珍贵树种苗木为研究对象,分析自然降温过程中苗木相对叶绿素含量、气体交换参数及叶绿素荧光参数等指标的变化,探讨低温胁迫对这6种苗木光合荧光特性的影响,并利用隶属函数法对6种珍贵树种耐寒能力进行了评价,以期了解这几种植物的抗寒能力差异及低温对其光合能力的影响,为扩大引种和栽培提供依据。结果表明,与对照相比,低温胁迫下6种珍贵树种苗木净光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）均有不同程度的下降,其中,格木、降香黄檀、闽楠、檀香、铁刀木净光合效率的下降很大程度上来源于非气孔因素抑制,而樟树净光合速率下降可能来源于气孔限制因素。闽楠、檀香和樟树水分利用效率（WUE）呈上升趋势,而格木与降香黄檀WUE均有不同程度的降低,表明闽楠、檀香和樟树能较好地协调碳同化和水分耗散。低温胁迫下6种珍贵树种Fm均有所下降,表明低温可对珍贵树种苗木叶片PSII反应中心的电子传递潜力产生明显的抑制,致使珍贵树种PSII的光能转换效率降低。降香黄檀、闽楠、檀香、铁刀木和樟树经历2次低温胁迫后qP呈现出持续下降的趋势,表明珍贵树种PSII反应中心的开放程度降低。在2次低温胁迫间格木、降香黄檀、闽楠和铁刀木qN差异不显著（p〉0.05）,表明珍贵树种具有过剩光能耗散机制,保护光合机构免受破坏。相关性分析结果表明,Pn与Gs、Tr、Fv/Fm、qP、qN、ETR和Fm存在极显著相关关系（p〈0.01）,表明Gs、Tr、Fv/Fm、qP、qN、ETR和Fm均可作为衡量植物光合能力的参数。隶属函数法分析结果表明,6种珍贵树种抗寒能力依次为格木〉樟树〉闽楠=檀香=铁刀木〉降香黄檀。总之,?     

Simultaneous removal of arsenate and fluoride from water by AI-Fe （hydr）oxides

A1-Fe （hydr）oxides with different A1/Fe molar ratios （4：1, 1：1, 1：4, 0：1） were prepared using a co- precipitation method and were then employed for simultaneous removal of arsenate and fluoride. The 4A1 ： Fe was superior to other adsorbents for removal of arsenate and fluoride in the pH range of 5.0-9.0. The adsorption capacity of the A1-Fe （hydr）oxides for arsenate and fluoride at pH 6.50.3 increased with increasing A1 content in the adsorbents. The linear relationship between the amount of OH released from the adsorbent and the amount of arsenate or fluoride adsorbent by 4A1 ： Fe indicated that the adsorption of arsenate and fluoride by A1- Fe （hydr）oxides was realized primarily through quantita- tive ligand exchange. Moreover, there was a very good correlation between the surface hydroxyl group densities of A1-Fe （hydr）oxides and their adsorption capacities for arsenate or fluoride. The highest adsorption capacity for arsenate and fluoride by 4A1 ： Fe is mainly ascribed to its highest surface hydroxyl group density besides its largest pHpzc. The dosage of adsorbent necessary to remove arsenate and fluoride to meet the drinking water standard was mainly determined by the presence of fluoride since fluoride was generally present in groundwater at much higher concentration than arsenate.     

Thermodynamic and kinetic studies on Cs+- and Sr2+-exchange in natural zeolite from Akita,Japan

Thermodynamic and kinetic studies on the adsorption of Cs⁺ and Sr²⁺ by Na-exchanged clinoptilolite-rich zeolite rock from Akita (Northern Japan) were performed for the purpose of nuclear waste treatment. The thermodynamic parameters such as selectivity coefficient, thermodynamic equilibrium constant, and standard free energy of exchange were evaluated. These values indicated that the selectivity order was determined as Cs⁺ > Na⁺ > Sr²⁺. In order to discuss the adsorption mechanism of Cs⁺ and Sr²⁺ onto Na-exchanged clinoptilolite, the effective diffusion coefficients were calculated and two kinetic models, pseudo-first-order and pseudo-second-order kinetic model, were tested. For all systems studied, chemisorption seems significant in the rate-controlling step, and the pseudo-second-order kinetic model provided the best correlation of the experimental data.     

Defluoridation of drinking water using Al3+-modified bentonite clay: optimization of fluoride adsorption conditions

Al³⁺-bentonite clay (Alum-bent) was prepared by ion exchange of base cations on the matrices of bentonite clay. Intercalation of bentonite clay with Al³⁺ was performed in batch experiments. Parameters optimized include time, dosage, and Al³⁺ concentration. Physicochemical characterization of raw and modified bentonite clay was done by X-ray fluorescence, X-ray diffraction, energy dispersive X-ray spectrometry attached to scanning electron microscopy, Brunauer–Emmett–Teller analysis, cation exchange capacity (CEC) by ammonium acetate method, and pH_pzc by solid addition method. Chemical constituents of water were determined by atomic absorption spectrometry (AAS), ion selective electrode (Crison 6955 Fluoride selective electrode) and a Crison multimeter probe. For fluoride removal, the effect of contact time, adsorbent dosage, adsorbate concentration, and pH were evaluated in batch procedures. The adsorption capacity of fluoride by modified bentonite clay was observed to be 5.7 mg g^?1 at (26 ± 2) °C room temperature. Maximum adsorption of fluoride was optimum at 30 min, 1 g of dosage, 60 mg L^?1 of adsorbate concentration, pH 2–12, and 1:100 solid/liquid (S/L) ratios. Kinetic studies revealed that fluoride adsorption fitted well to pseudo-second-order model than pseudo first order. Adsorption data fitted well to both the Langmuir and Freundlich adsorption isotherms, hence, confirming monolayer and multilayer adsorption. Alum-bent showed good stability in removing fluoride from ground water to below the prescribed limit as stipulated by World Health Organization. As such, it can be concluded that Alum-bent is a potential defluoridation adsorbent which can be applied in fabrication of point of use devices for defluoridation of fluoride-rich water in rural areas of South Africa and other developing countries. Based on that, this comparative study proves that Alum-bent is a promising adsorbent with a high adsorption capacity for fluoride and can be a substitute for conventional defluoridation methods.