企业员工个体安全行为的人类动力学实证研究

对员工不安全行为的定量分析是理解安全生产事故复杂系统的基础.班组或群体的集体行为往往表现为复杂有序,具有一定的稳定性和适应性;而个体行为尽管有企业制度和纪律的约束,却仍有很大的随机性.为了探究企业员工不安全行为的动力学规律,跟踪观察某大型企业作业员工930 d,将员工相继不安全行为的发生看作排队理论中具有特定时间序列的随机过程.结果表明,就员工个体而言,其不安全行为的间隔时间分布可以用幂律函数近似描述,且幂指数和员工的活跃程度正相关;并进一步分析出企业员工相继不安全行为具有以艾宾浩斯遗忘曲线为特点的“阵发”性;从幂指数角度分析了员工日常作业中的不安全行为的优劣特点,比较了人类活动中的各种随机行为与员工在企业生产中的不安全行为在时间统计上的特性.这表明企业制定安全管理制度及实施安全培训工作都应从人类普遍问题和员工个体特点两方面入手.     

基于SEM的机组资源管理对机组人为差错的影响研究

为研究机组资源管理对机组人为差错的影响,以沟通和交流、领导管理技能、监控/质询、情景意识、决策及工作负荷作为机组资源管理变量,将人为差错分为认知差错和操作差错,利用230份飞行员的问卷调查数据,采用结构方程模型(SEM)的方法,构建有关机组资源管理与机组认知差错及操作差错关系的结构方程模型.结果表明:沟通和交流与操作差错显著相关;领导管理技能与认知差错及操作差错显著相关;监控/质询与认知差错及操作差错显著相关;情景意识与认知差错及操作差错显著相关;决策与操作差错显著相关;工作负荷与认知差错及操作差错显著相关;认知差错与操作差错显著相关.根据上述影响关系提出了建设团队氛围、培养机组成员的协同工作和加强机组成员的情景意识保持能力等措施.     

Unveiling soil degradation and desertification risk in the Mediterranean basin: a data mining analysis of the relationships between biophysical and socioeconomic factors in agro-forest landscapes

Soil degradation and desertification processes in the Mediterranean basin reflect the interplay between environmental and socioeconomic drivers. An approach to evaluate comparatively the multiple relationships between biophysical variables and socioeconomic factors is illustrated in the present study using the data collected from 586 field sites located in five Mediterranean areas (Spain, Greece, Turkey, Tunisia and Morocco). A total of 47 variables were chosen to illustrate land-use, farm characteristics, population pressure, tourism development, rainfall regime, water availability, soil properties and vegetation cover, among others. A data mining approach incorporating non-parametric inference, principal component analysis and hierarchical clustering was developed to identify candidate syndromes of soil degradation and desertification risk. While field sites in the same study area showed a substantial similarity, the multivariate relationship among variables diverged among study areas. Data mining techniques proved to be a practical tool to identify spatial determinants of soil degradation and desertification risk. Our findings identify the contrasting spatial patterns for biophysical and socioeconomic variables, in turn associated with different responses to land degradation.     

重庆金佛山降雪中飞灰单颗粒特征及来源解析

大气降雪能够保存大气环境信息,是研究区域环境的良好介质.位于渝黔交接带的金佛山海拔2 251.1 m,冬季降水以降雪的形式出现,周边区域人类活动强烈.关于该区域大气气溶胶中的飞灰单颗粒特征的研究比较缺乏.本研究采集了金佛山5个降雪样品,运用扫描电镜及X能谱分析联用系统(SEM-EDS)对样品中的132个飞灰进行单颗粒形貌、化学组成分析.结果表明,研究区降雪中存在大量球形飞灰,包含光滑颗粒、粗糙颗粒及聚合体颗粒3种形态,分别占统计颗粒的80.31%、14.39%和5.30%;平均粒径1.64μm,平均环度1.09.按主导化学元素分为富硅类、富碳类、富铁类、富铝类及富钛类5种,所占比例分别为34.09%、49.24%、12.88%、2.27%和1.52%.结合气象资料、气团后向运移轨迹和飞灰性质,推测富碳类飞灰可能主要来自于生活排放源和工业活动;富硅类飞灰可能来自于渝西、黔北、湘中、浙赣一带及粤西的火力发电厂等高温燃煤工业;富铁类及富钛类飞灰则可能来源于渝西和黔北、湘中的钢铁厂、轧钢厂等金属冶炼活动.     

潮间带湿地碳循环及其环境控制机制研究进展

有高等植被覆盖的潮间带湿地（红树林沼泽、盐沼）植被生产力高,有机碳分解速率低,CH4排放较弱,碳沉积速度快,是单位面积碳封存速率最高的生态系统之一。作为全球“蓝色碳汇”的主要贡献者,潮间带湿地在减缓含碳温室气体排放,降低全球温室效应方面具有重要潜力。潮间带湿地大多地处经济发达和人口密集的河口海岸地区,近年来其碳汇功能受到了越来越多人为干扰的威胁,正在发生着的气候变化则更增加了这种碳汇功能的不确定性。在全球变化背景下,对潮间带湿地碳循环及其环境控制机制的深入了解可以帮助更好地管理这种具有重要碳减排潜力的生态系统。文章综述国内外的相关研究,分析了潮间带湿地碳循环的基本过程和环境影响因素,探讨了多种人为干扰和气候变化要素对潮间带湿地碳循环的影响。潮间带湿地碳循环的基本过程主要包括垂直方向土壤（水）-大气界面和植被-大气界面CO2、CH4交换和沉积过程驱动的碳封存,以及水平方向与近海的碳交换。潮间带湿地的碳循环主要受潮汐/流、光合有效辐射、温度、盐度、水位、植物群落特征等非生物和生物因素的影响。围垦、富营养化、放牧很可能削弱潮间带湿地的碳汇功能,而外来植物入侵却可能在一定程度上增加其碳汇潜能。海平面上升、气温升高会增加潮间带湿地碳汇功能的脆弱性,CO2浓度升高的作用依赖于优势植物群落的光合作用途径,而多种并存气候变化要素的作用则更为复杂。全球范围内大量潮间带湿地已经遭受破坏甚至丧失,水文调控是对受损潮间带湿地碳汇功能进行修复和重建的有效措施。未来的研究需要更好的理解多种并存气候变化要素,及人为干扰和气候变化同时存在对潮间带湿地碳循环的交互效应,利用过程模型预测不同人为干扰和气候变化情境下潮间带湿地碳收支变化规律,并完善受损潮间带湿地碳汇功能修复的基础理论和实施方法。     

Organochlorine levels in human blood from residents in areas of limited pesticide use in Sudan

Ninety-nine human blood samples were collected from the riverine region of northern Sudan and the traditional and mechanized rain-fed areas of western and eastern Sudan, representing areas of limited pesticide use in Sudan. Blood samples were analyzed for organochlorine pesticides by gas liquid chromatography (GLC) followed by electron-capture detection (ECD). p,p′-DDE (a metabolite of DDT), heptachlor epoxide, β-hexachlorocyclohexane (β-HCH), and dieldrin were detected in all locations surveyed. The level of total organochlorine burden was highest in the traditional rain-fed area, followed by the mechanized rain-fed area, and the riverine area. A highly significant correlation was observed between total organochlorine blood burden and the age of the donors (r = 0.608**).     

Effects of UV-A LED light irradiation on growth of cultured RAW 264.7 cells

The aim of this study was to examine the effects of ultraviolet A (UV-A) irradiation-induced damage on cultured macrophage RAW 264.7 cells and determine which components produced these manifestations. RAW 264.7 cells were irradiated with 365 nm UV-A using a light-emitting diode (LED). Cell viability and damage were determined using a calcein-AM and propidium iodide dual-staining assay and lactate dehydrogenase leakage, respectively. Intracellular reactive oxygen species (ROS) were measured by H₂DCF-DA. The components of ROS in each medium were measured using an electron paramagnetic resonance (EPR) spectrometer in the presence of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and 2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide (TPC). While UV-A irradiation for 2 min significantly suppressed cell growth, LDH leakage did not occur. Addition of N-acetyl cysteine restored inhibition of cell proliferation, and reduced intracellular ROS levels. The EPR signal in the presence of TPC increased with time but was decreased by sodium azide. In addition, a typical EPR spectrum was obtained in the presence of DMPO, indicating the presence of a hydroxyradical. The spectrum was diminished by L-histidine. Data suggest that ROS generated in cells or culture medium by UV-A irradiation is predominantly singlet oxygen, and this singlet oxygen suppressed cell proliferation.     

Nanosilica exerts cytotoxicity and apoptotic response via oxidative stress in mouse embryonic fibroblasts

Nanoscale silica is an important industrial material and extensively used in medicines. The objective of this study was to determine potential cytotoxicity and genotoxic effects attributed to nanosilica exposure in mouse embryonic fibroblasts (L929) cells. Nanosilica produced mild cytotoxicity in L929 cells. Results showed that nanosilica increased thiobarbituric acid reactive substance levels and enhanced superoxide dismutase activity but decreased levels of glutathione. This was accompanied by a concomitant generation of reactive oxygen species, loss of mitochondrial membrane potential, and activation of caspase-3 activity. In addition, in the single-cell gel test, nanosilica (50–300 μg/ml) at two treatment times 24 and 48 hr produced concentration- and time-dependent increase of DNA damage. Therefore, the obtained results indicate that nanosilica may induce genotoxic effects in cultured L929 cells associated with induction of oxidative stress.     

Studying developmental neurotoxic effects of bisphenol A (BPA) using embryonic stem cells

There is little to no toxicity information regarding thousands of chemicals to which people are exposed daily. In fact, of the 84,000 chemicals listed in the United States Toxic Substances Control Act Inventory, there is limited information available on their effects on neural development (Betts, 2010 and US EPA, 2015). The number of chemicals tested remains low due to the high cost of conducting multi-generational animal studies and the lack of alternative testing methods.     

Assessment of Bisphenol A (BPA) neurotoxicity in vitro with mouse embryonic stem cells

The adverse effects of environmental pollution on our well-being have been intensively studied with many in vitro and in vivo systems. In our group, we focus on stem cell toxicology due to the multitude of embryonic stem cell (ESC) properties which can be exerted in toxicity assays. In fact, ESCs can differentiate in culture to mimic embryonic development in vivo, or specifically to virtually any kind of somatic cells. Here, we used the toxicant Bisphenol A (BPA), a chemical known as a hazard to infants and children, and showed that our stem cell toxicology system was able to efficiently recapitulate most of the toxic effects of BPA previously detected by in vitro system or animal tests. More precisely, we demonstrated that BPA affected the proper specification of germ layers during our in vitro mimicking of the embryonic development, as well as the establishment of neural ectoderm and neural progenitor cells.