CdS-TiO_2/MWCNTs结构表征及其光催化性能

采用溶胶-凝胶法,制备了多壁碳纳米管(MWCNTs)负载的双组分复合半导体光催化剂CdS-TiO2/MWCNTs。通过透射电镜(TEM)、比表面分析(BET)、X射线衍射(XRD)和紫外-可见吸收光谱(UV-vis)等分析方法对光催化剂进行了结构表征,并考察了CdS-TiO2/MWCNTs对甲苯降解的光催化性能。结果表明:纳米活性粒子CdS-TiO2均匀负载于MWCNTs上,比表面积、光吸收阈值和强度增大,活性粒子间以及活性粒子与载体之间具有协同作用,有利于光催化性能的提高,CdS-TiO2/MWCNTs在主波长为254 nm紫外光照射下对甲苯的降解效果较好,去除率可达55.3%。     

东莞市污水处理厂升级改造工艺路线初探

针对东莞市38个污水处理厂的实际情况,通过对目前城市污水处理厂常用的二级处理工艺进行技术升级改造时可能采用的深度处理工艺技术的综合分析比较,推荐了NPR、CNR、人工湿地三种工艺作为尾水的深度处理备选技术,提出了东莞市污水处理厂升级改造应优先采用CNR工艺,并可为我国不同地区、不同发展时期满足不同的水质需求进行污水处理厂工艺升级改造提供技术支持。     

印刷线路板在复合环境下的腐蚀

印刷线路板几乎会出现在每一种电子设备当中,它是以绝缘材料辅以导体配线所形成的结构元件。印刷线路板的腐蚀形式符合大气腐蚀的基本规律,但又有自己的特点。本文概述了印刷线路板在气体污染物、灰尘、潮湿、高温等多因素复合环境条件下的失效形式及腐蚀机理,其主要的腐蚀形式是:电偶腐蚀、电解腐蚀和缝隙腐蚀;文中还简单总结了印刷线路板腐蚀的主要影响因素,其主要的影响因素是:湿度、温度、腐蚀性气体和固态污染物等。     

Carbonaceous matter and PBDEs on indoor/outdoor glass window surfaces in Guangzhou and Hong Kong,South China

Organic films, collected from indoor and outdoor window surfaces in Guangzhou and Hong Kong of South China, were analyzed to quantify their organic carbon (OC), elemental carbon (EC), and polybrominated diphenyl ethers (PBDEs) content. The highest concentrations of OC, EC, and BDE-209 were found in Guangzhou with values of 10 000 μg m^?2, 2200 μg m^?2, and 4000 ng m^?2, respectively, and the highest concentration of Σ₇PBDE (sum of BDE-28, -47, -99, -100, -153, -154 and -183) was found in Hong Kong with a value of 25 ng m^?2. In most cases, the concentrations of PBDEs were higher in the exterior films than those in the interior films with BDE-209 as the predominant congener in both cities, suggesting that PBDEs mainly come from ambient environment, and deca-BDE accounts for major PBDE consumption. The growth rates of organic film on window surfaces were fast at the beginning, and reached a consistent level afterwards. The evolution rates ranged from 2.6 to 11 nm day^?1 for “bulk film”, while from 0.06 to 0.92 nm day^?1 for “pure film”. The concentrations of PBDEs on the window surfaces did not increase with the growth time, suggesting that the window surface may provide a good place for photo-degradation of PBDEs.     

芳烃类化合物结构表征及-lgK_(ow)定量预测

为探寻芳烃类有机物结构与正辛醇/水分配系数(-lgK_(ow))的关系,应用分子顶点及顶点相互作用矢量对芳烃类有机物进行了结构表征.采用多元线性回归及逐步回归建立了3个定量结构-性质关系的-lgK_(ow)模型.经过比较,发现模型M3具有最佳模拟结果,此时模型的复相关系数为0.946,标准偏差为0.392.为检验模型的稳定性,采用留一法(leave-one-out)对模型进行了交互检验,复相关系数为0.920,标准偏差为0.429.     

Competition of coagulation sink and source rate: New particle formation in the Pearl River Delta of China

The coagulation sink and its role in new particle formation are investigated based on data obtained during the PRIDE-PRD2004 campaign at Xinken of Pearl River Delta, China. Analysis of size distributions and mode contributions of the coagulation sink show that the observed higher load of accumulation mode particles impose a significant effect on the coagulation sink and result in higher coagulation sinks at Xinken despite of the lower total particle number compared with other areas. Hence it is concluded that the higher coagulation sink may depress the occurrence frequency of new particle formation events. The strategies targeting at controlling accumulation mode particles may have influences on the frequency of new particle formation events at this area. The factors affecting the coagulation sink are evaluated. The relatively lower ambient relative humidities may weaken the coagulation sink and facilitate the occurrence of new particle formation events during noontime, while the surmise of nucleation and growth involving organic matter may imply an actually higher coagulation sink than expected. These factors have a significant influence on the ultimate fate of the newly formed nuclei and new particle formation. A comparison of event and non-event days indicates that the coagulation sink is not the only decisive factor affecting new particle formation, other factors including the precursor vapors and photochemical activity are none the less important either. Competition of coagulation sink and high source rate leads to the occurrence of new particle formation events at Xinken.     

In silico prediction of Tetrahymena pyriformis toxicity for diverse industrial chemicals with substructure pattern recognition and machine learning methods

There is an increasing need for the rapid safety assessment of chemicals by both industries and regulatory agencies throughout the world. In silico techniques are practical alternatives in the environmental hazard assessment. It is especially true to address the persistence, bioaccumulative and toxicity potentials of organic chemicals. Tetrahymena pyriformis toxicity is often used as a toxic endpoint. In this study, 1571 diverse unique chemicals were collected from the literature and composed of the largest diverse data set for T. pyriformis toxicity. Classification predictive models of T. pyriformis toxicity were developed by substructure pattern recognition and different machine learning methods, including support vector machine (SVM), C4.5 decision tree, k-nearest neighbors and random forest. The results of a 5-fold cross-validation showed that the SVM method performed better than other algorithms. The overall predictive accuracies of the SVM classification model with radial basis functions kernel was 92.2% for the 5-fold cross-validation and 92.6% for the external validation set, respectively. Furthermore, several representative substructure patterns for characterizing T. pyriformis toxicity were also identified via the information gain analysis methods.     

如何建立良好的安全理念

从职工的思想政治工作入手,从职工的安全观念的树立、安全技能的培养、生产技能的提高等诸多方面告诉我们如何实现安全生产、文明生产所需要的安全理念。     

基于VEGA和DCGA的化工园区布局优化研究

化工园区布局优化是一个复杂的多目标优化问题,建立了以事故风险和经济收益为两个优化指标的化工园区布局优化模型,以潜在死亡人数(PLL)表征事故风险,以销售收入表征经济收益;从算法的正确性、有效性及其搜索性能上提出了三条化工园区布局优化算法性能的评价准则;基于向量评价遗传算法(VEGA)和基于确定性拥挤机制的小生境遗传算法(DCGA)分别对化工园区布局优化进行研究,并对比分析了优化计算结果,得出:建立的化工园区双目标布局优化模型和提出的优化方法是可行的,计算所得的Pareto最优解对化工园区布局具有较好的参考价值;VEGA算法仅能满足部分准则要求,而DCGA算法能同时满足三条评价准则要求,可知DCGA算法适用于化工园区布局优化。     

SIL评估及HAZOP分析技术在海洋平台安全评估中的应用

针对海洋平台安全仪表系统安全可靠性要求的提高,分析海洋平台安全仪表系统SIL评估及HAZOP分析方法,对SIL评估的必要性、目的和内容、方法与流程进行论述,对SIL等级选择的HAZOP和LOPA分析方法进行介绍,对SIL评估过程中的重要数据问题进行阐述,对SIL等级验证中各参数和失效数据的选取进行说明。通过案例进一步论述SIL评估及HAZOP分析技术的要点和实施步骤,针对该案例提出了提高SIL等级的建议和措施,为海洋平台安全仪表系统的SIL评估提供重要的参考和依据。