大气中痕量挥发性有机物气相色谱保留时间的预估

为探寻环境中挥发性有机物气相色谱保留行为与结构的关系,应用三维原子场全息作用矢量(3D-HoVAIF),对39个大气中痕量挥发性有机物进行了结构表征.采用逐步回归对变量进行筛选,建立了8变量定量结构色谱保留相关(QSRR)模型,模型的复相关系数为R-1=0.985; 进而将3D-HoVAIF矢量与相对分子质量结合,建立了9变量QSRR模型,模型的复相关系数为R-2 = 0.991; 采用留一法交互检验,结果分别为RCV,1 = 0.970、RCV,2 =0.978,表明模型具有良好的估计能力和稳定性.     

Occurrence of organotins in the Yangtze River and the Jialing River in the urban section of Chongqing, China

The occurrence of organotins in the Yangtze River and the Jialing River in the urban section of Chongqing, China and their impact on drinking water waterworks are reported in this study. Water samples were extracted by solid-phase microextraction and measured using a gas chromatograph with mass spectrometer. The results showed that the rivers studied were polluted by both butyltins and phenyltins and that the butyltin species was the dominant pollutant. Butyltins, especially monobutyltin, were detected in all 18 sampling stations, and phenyltins were detected only in 11 sampling stations. Majority of the organotins were MBTs with concentrations varying from 27.3 to 1,145.8 ng Sn L^?1. Diphenyltin and dibutyltin were the second most common with the highest levels of 113.7 and 202.5 ng Sn L^?1, respectively. Monophenyltin, tributyltin, and triphenyltin had the lowest detection rates with concentration levels of 9.7, 161.8, and 37.2 ng Sn L^?1, respectively. Some of the organotins were also detected in drinking water waterworks, which posed a threat to the water quality of Chongqing.     

Biosorption properties of Cd(II), Pb(II), and Cu(II) of extracellular polymeric substances (EPS) extracted from Aspergillus fumigatus and determined by polarographic method

Extracellular polymeric substances (EPS) were extracted from Aspergillus fumigatus using cationic exchange resin technique. The EPS were mainly composed of polysaccharide and low quantities of protein and nucleic acid. Biosorption of Cd(II), Pb(II), and Cu(II) of EPS was investigated as a function of pH using differential pulse polarography and the Ruzic model. Results showed that the EPS biosorption capacity determined using either the direct titration curves i?=?f(C _M) or the method proposed by Ruzic (Analytica Chimica Acta 140:99–113, 1982) were coincident. Cu(II) had the highest affinity with EPS followed by Pb(II) and Cd(II). The total number of binding sites for Cu(II) and Cd(II) increased with pH in the range of 4.0–7.0. Similar trend was observed for Pb(II) at pH?4.0–5.0, while precipitates were observed at pH?6.0 and 7.0. The conditional binding constants of these three metals displayed low levels of fluctuation with pH and ranged from 4.02?±?0.02 to 5.54?±?0.05.     

高职英语教师在教学中的中介作用

费厄斯坦的中介理论指出：教师在教学中承担的中介角色应当是学生知识建构的中介者和帮助者．从新形势下的高职英语教学的特殊性及其现状出发，根据中介理论，分析了高职英语教师的中介角色，并探讨了如何有效地发挥其中介作用．参9．     

某厂化学装置爆炸对设备房结构的损坏——调查与模拟分析

在对某厂化学爆炸所作的现场调查的基础上，对设备房钢筋混凝土框架结构构件的受损状况进行了分类描述，采用有限元方法对框架结构在静力和爆炸冲击荷载下的反应进行了模拟分析，分析结果与现场调查情况基本一致，给出了一些有意义的结论。     

风浪扰动对太湖水体中砷在水相-悬浮物相之间分配的影响

在太湖冬季不同风速下(0.8、1.8、2.7、3.2、4.0 m·s-1)采集了不同深度(水深0.1、1.0和1.8 m,分别记为上、中和下层)的水样,测定了水体和悬浮物中的砷含量及水质参数,计算了砷在两相之间的分配系数,以期了解在太湖生物活动最低的阶段,风浪扰动作用对砷在水相和悬浮物相之间分配的影响.结果显示,随着风浪作用的加强,水体总砷含量有所增加,相应的悬浮物总砷含量及砷的分配系数降低,说明风浪作用可以降低悬浮物吸附砷的能力,以至于促进砷从悬浮物中的释放,进而使水体中的溶解态砷增加.相关性分析及变化趋势比较分析发现,砷分配系数的降低与在风浪扰动的影响下悬浮物浓度和溶解氧的增加,以及叶绿素a浓度的下降有关.不同风速下各参数的垂向分布变化显示,风浪扰动对中下层的砷分配系数以及中层的悬浮物砷含量影响较大;风速变大时,中层溶解态砷含量升高,上层与下层溶解态砷含量降低;而风浪扰动作用对水体总砷的分层变化影响不大.悬浮物浓度、砷浓度及分配系数均在3~4 m·s-1风速下发生变化,且呈现与之前不同的分层特征.4 m·s-1可能是一个临界风速,在4 m·s-1以上的风速下风浪占主导作用,而4 m·s-1以下是湖流与风浪共同作用的结果.     

西充县新型城镇化助推城市环境管理创新研究

通过寻访调查,资料信息收集、文献查阅等形式研究总结了四川省西充县的发展新战略成功经验,实现了新型城镇化与城市环境管理有机结合。将这成功经验进行研究提炼形成一种理论模式。     

动态飞行模拟器运动控制系统软件设计

目的研究动态飞行模拟器(DFS)运动控制系统软件功能、架构、模块、接口设计以及软件具体实现方法。方法在DFS工程控制系统功能及软件设计基础上,对运动控制系统功能及其与工程控制系统关系进行分析,结合现有软件设计方法及数据通讯方式,对软件进行架构设计、接口设计、模块设计,并结合软件运行环境对系统上位机软件进行设计。结果采用合适的编程语言实现了运动控制系统软件及其上位机软件的设计,并通过了工程实践对软件设计方法有效性的验证。结论工程实践表明文中所述DFS运动控制系统软件设计方法切实可行,能够满足工程应用要求。     

基于奇异谱的精密离心机空气轴承主轴回转系统误差分析

目的提出一种精密离心机主轴回转系统误差分析方法。方法基于奇异谱分析对主轴回转误差的趋势进行提取,采用4个安装指定位置的高精度传感器测量轴回转相对位置变化,对数据进行奇异谱分析,采用差分奇异谱的准则来确定重构数据所需的基本分解信号,重构获得的数据为测量数据的趋势部分,即为主轴回转的系统误差。结果重构获得的数据趋势在各个转速下均与实测结果趋势基本一致。结论基于奇异谱分析的精密离心机空气轴承主轴回转误差趋势分析方法能够有效地用于补偿修正该系统误差。