Environmental toxicity monitoring using electrochemical biosensing systems

Environmental monitoring faces the challenge of measuring an increasing number of analytes at ever decreasing concentrations. Since not all species of a given analyte have the same detrimental impact on the environment, new analytical devices and techniques are required to distinguish between the different species of a pollutant or different groups of pollutants. This paper describes analytical techniques based on biomaterials that are toxically sensitive to pollutants. This approach permits the biomonitoring of certain compounds by looking at their toxic properties. Although these techniques are based on a sound analytical strategy, their applications are limited because most of the interactions between the biological material and the analyte are irreversible. Additionally, the immobilised biological material has a limited stability. Several biomonitoring strategies based on electrochemical biosensing are discussed here and how to recover the bioactivity of biosensing system, both in discrete and automated procedures, is also reviewed.     

Speciation and quantitation of degradation products of silicones (Silane/Siloxane Diols) by gas chromatography—mass spectrometry and stability of dimethylsilanediol

Gas chromatography-mass spectrometry (GC-MS) methodology was developed to speciate and quantitate several degradation products of polydimethylsiloxane (PDMS) in soil. We have demonstrated that the major degradation product,viz., dimethylsilanediol, can be readily analyzed by GC-MS without derivatization as commonly practiced in analyzing such materials. A mixture of linear siloxane diols (n = 1–5, wheren is the number of Me₂SiO units), and cyclic dimethylsiloxanes (n = 4–6) was resolved by GC-MS. We also found that peak identity of various diols required that GC-MS is done in the chemical ionization (CI) mode, since the electron impact (EI) ionization mode produced similar mass fragmentation patterns for diols and cyclics containing the same number of silicon atoms. For siloxane diols, detection limits ranged from 100 pg (forn = 1) to 1 ng (for n = 5). For cyclics, the detection limit was about 1 pg. Dimethylsilanediol, known to be unstable even in the solid state, was shown by NMR techniques to be stable in aqueous solution at <0.1% concentration. A 100-ppm solution was stable for over a year. Purity check for dimethylsilanediol is best carried out by Si-29 solid-state NMR technique.     

电场、磁场和电磁场的环境问题

针对近年来越来越突出的输变电工程电磁环境纠纷等问题,从电磁场理论的角度,对电场、磁场和电磁场的传播及特性进行分析,以求正确地分析与解释电磁场辐射问题,减少误解和随之产生的不必要纠纷.     

磁性微球负载光催化剂失活特性及再生方法研究

TiO2/SiO2/Fe3O4在连续使用过程中存在失活现象并表现出吸附能力的降低,在实验基础上提出了超声波在线再生的解决方案;测试结果表明,TiO2/SiO2/Fe3O4在重复使用10次及连续使用130h条件下可保持其催化活性不变。     

上海崇明岛沉积物重金属污染的磁学研究

系统分析了上海崇明岛的8个样点沉积物样品的重金属元素和磁化率、频率磁化率以及饱和等温剩磁等磁参数之间的关系,结果表明:介于轻度污染和偏中度污染的重金属Pb、Cr、Cu、zn元素与磁性矿物特别是亚铁磁性矿物之间在赋存形态、沉积特征上存在一定的联系,因此磁性测量可作为沉积物重金属污染记录信息提取的辅助手段,但不同的磁性参数对重金属的指示程度不同,由于本研究以较粗的多畴亚铁磁性矿物为主,同时质量磁化率(x)、非磁滞剩磁磁化率与饱和等温剩磁的比值(XARM/SIRM)对重金属元素含量变化比较敏感,因而X、XARM/SIRM可作为重金属含量的替代指标.最后在重金属元素和磁性参数相关性的基础上建立了磁诊断线性回归模型.     

基于有限元法对亥姆霍兹线圈磁场的分析

为进一步明确亥姆霍兹线圈所产生磁场的近场特性,文中尝试采用基于有限元方法的ANSYS软件对亥姆霍兹线圈进行了分析,首先采用ANSYS软件对亥姆霍兹线圈进行三维实体有限元模型和仿真,并将结果与用MATLAB语言绘制磁感应强度的空间分布图进行比较.仿真结果说明ANSYS有限元模型优于MATLAB语言,并且通过实验验证了所建的三维亥姆霍兹线圈有限元模型的有效性和正确性.     

爆炸磁频率发生器关键技术研究

对爆炸磁频率发生器的关键技术和国内外研究现状进行了论述,重点讨论了爆炸磁频率发生器的工作原理,从等效电路出发,分析了参数选择要求以及注意事项;分析了辐射天线以及攻击目标耦合形式等内容;对国内外的应用及发展前景发表了看法。     

重庆市典型变电站站场外工频电磁场实测分析

对重庆市110kV、220kV典型变电站站场外的工频电磁场进行实测并归纳总结了测量结果,根据测量得到的实际数据,得出变电站站场外工频电磁场的分布规律及变化趋势,表明变电站站场外工频电磁场均能满足相关规定要求,工频电磁场随主变容量的增大而呈增大趋势,随与主变距离的增加而减小,同时,户内变电站对工频电磁场的影响也比户外变电站要小。     

220kV输变电工程电磁辐射环境影响研究

文章以黄石220kV向家咀输变电工程为研究对象,通过现场调研和监测,根据《500kV超高压送变电工程电磁辐射环境影响评价技术规范》(HJ/T24-1998)附录A、B、C推荐的计算模式并借助计算机软件定量的预测出该项目投产运行后对周边环境电磁辐射的环境贡献值,同时通过测量同电压等级、容量以及同导线型号的宜都220kV郭飞线(郭飞变电站至飞凤变电站)的电磁辐射现状验证预测结果,得出研究结论并对输变电线路电磁辐射提出保护措施和建议。     

磁性微球负载光催化剂的吸附特性研究

在TiO2/SiO2/Fe3O4物化特性的研究中,通过测定方法的改进首次获得光照反应阶段TiO2/SiO2/Fe3O4吸附量与溶液残余量间的定量关系(以苯酚为例,结果表明:在光照及无光照条件下TiO2/SiO2/Fe3O4遵循不同的吸附规律,以后者取代前者存在明显缺陷;揭示了凝聚现象是导致TiO2/SiO2/Fe3O4光活性降低的主要原因。