磁性海泡石吸附水中重金属离子的特性及机理

以化学共沉淀法制备磁性海泡石,通过设置一个外加磁场实现对其的分离回收.主要研究了磁性海泡石吸附水中重金属离子的特性,并结合XRD、FT-IR分析结果探讨了吸附机理,结果表明,磁性海泡石对重金属阳离子的吸附效果优于阴离子;初始pH对磁性海泡石吸附重金属离子的影响不仅取决于磁性海泡石表面的电荷性质,而且与重金属离子的水解能力有关;在吸附过程中,磁性海泡石的物相结构没有发生明显改变,吸附机理表现为离子交换和配合吸附作用.     

A shell-based magnetic field model for magnetic proximity detection systems

Several magnetic proximity detection systems have been developed for mining vehicles and mobile machinery to protect nearby workers. Magnetic field generators are often used in these systems to establish magnetic fields around the equipment. A sensor worn by a worker provides a measurement of the magnetic flux density that is used to estimate the proximity to the machine. The proximity detection systems currently available for underground mining equipment are capable of identifying whether a worker is near the machine. However, it is a challenge for these systems to accurately locate the worker. Mining machines, which have fast-moving, articulated parts, present hazards that change depending on the situation at hand as well as the specific location of the worker. In addition, the dynamic nature and confined spaces of the mining environment often demand that the workers be close to the machinery. Therefore, in many cases, simply knowing the proximity of a worker may be inadequate. To provide the most effective protection, it would be advantageous to know the worker’s exact location relative to specific parts of the machine. To lay the foundation for measuring such a location, we have developed a shell-based model of the magnetic flux density distribution for a ferrite-cored generator. This paper will present an analysis of the model along with a model construction process. Also presented are the laboratory test results of a prototype system that implements this model to determine the exact location of a magnetic sensor using the fields from two generators.     

几种焦化废水深度处理技术的比较

分别采用Fenton试剂氧化法、固定床离子交换树脂吸附法和流化床磁性树脂吸附法对某焦化厂焦化废水生化工艺出水进行深度处理.试验结果表明:Fenton试剂氧化法处理后出水COD去除率最高达75.4％,色度去除率达89.1％;固定床离子交换树脂吸附法COD去除率为49.4％,色度去除率为96.5％;流化床磁性树脂吸附法COD去除率为58.2％,色度去除率为90.2％.Fenton试剂氧化法COD去除率较高,固定床离子交换树脂吸附法和流化床磁性树脂吸附法色度去除率较高.综合考虑,Fenton试剂氧化法具有更高的工程应用价值.     

常介孔型磁性离子交换树脂的制备及其效能——针对典型藻源含氮有机物

以甲基丙烯酸缩水甘油酯为单体,利用单体聚合法制备了介孔型磁性离子交换树脂(m-MIER),并在表征其基本性状的基础上,初步分析了其对典型藻源含氮有机物(藻蓝蛋白、氨基酸)的去除效能.为便于比较,研究过程中同步进行了磁性离子交换树脂(MIEX^®)的研究.研究结果表明,m-MIER是以氯为交换基团的介孔型材料,其孔径为2~60nm;与MIEX^®相比,m-MIER具有相似的湿视密度、粒径,更丰富的孔隙结构、更大的交换容量(1.15g/cm³, 150~200 μm, 0.1852cm³/g, 3.16mmol/g Vs 1.20g/cm³, 150~180 μm, 0.0184cm³/g, 2.23mmol/g);XPS图谱分析结果表明其内核成分主要为Fe₃O₄,且为季胺型阴离子交换树脂.针对藻源含氮有机物的去除结果表明,m-MIER对藻蓝蛋白、特定氨基酸的去除效果明显优于MIEX^®,且去除效果与氨基酸的种类显著相关.     

上海崇明岛农田土壤中多氯联苯的残留特征

在上海崇明岛采集了101个耕层土壤样品,利用GC-μECD测定了8种多氯联苯(PCBs)浓度,并对其进行多元统计分析,探讨了其可能的污染来源.结果表明,样品PCBs浓度范围为n.d.~261ng/g,均值为56.0ng/g,低氯联苯含量和检出率均较高.不同土壤利用方式对PCBs残留量有一定影响,表现为水稻田土壤>大棚蔬菜西瓜田土壤>露天蔬菜西瓜田土壤.主成分分析和相关性研究结果显示,土壤中低氯联苯同系物间相关性较好,污染来源可能为同一类.     

镉胁迫下磁场对绿豆幼苗根茎叶显微结构的影响

以绿豆(Vigna radiata)为实验材料,比较研究了不同剂量磁场处理绿豆种子对种子电导率、幼苗生长和叶绿素含量的影响以及镉胁迫绿豆幼苗根、茎、叶显微结构的影响.结果表明:1)与对照相比,400mT、600mT、800mT、1000mT磁场均显著提高了种子电导率,且随着磁场强度的增加电导率显著增大;2)400mT、600mT、800mT磁场均能显著提高绿豆幼苗叶片叶绿素含量和幼苗发育,比较而言600mT效果最好,1000mT处理则显著降低了叶片叶绿素含量,抑制了幼苗发育;3)与对照组相比,5μmol·L-1镉胁迫绿豆幼苗栅栏组织和海面组织细胞排列紧密,厚度变薄,而种子经过600mT磁场预处理后再进行镉胁迫,厚度接近对照组.对于茎和根而言,镉胁迫抑制了形成层细胞分裂,维管束体积缩小,而种子经过600mT磁场预处理后再进行镉胁迫,其维管束体积增大接近对照组.表明,600mT磁场预处理种子可改善镉胁迫对幼苗的伤害.     

Currarino triad: concurrent US and MRI diagnosis in the fetus and the mother

We report an unusual case of the complete Currarino triad diagnosed in a fetus at 21 weeks' gestation by means of prenatal ultrasonography (US). The highly suspicious findings in the fetus were accompanied by analogous US findings in the mother who suffered from mild symptoms of up to that time unrecognized Currarino triad. Consecutively, magnetic resonance imaging (MRI) confirmed the findings simultaneously in the fetus and in her mother. This is the first report describing the prenatal diagnosis of Currarino triad without the background of positive family history. To our knowledge, the prenatal MRI findings of Currarino triad have not yet been published. Copyright © 2002 John Wiley & Sons, Ltd.     

Klippel–Trenaunay–Weber (KTW) syndrome: the use of in utero magnetic resonance imaging (MRI) in a prospective diagnosis

The diagnosis of the Klippel–Trenaunay–Weber (KTW) syndrome is rarely made antenatally. We report the use of both ultrasound and in utero magnetic resonance imaging (MRI) in the prenatal diagnosis of this syndrome. This is the first report of the use of prenatal MRI in the diagnosis of this condition. There was concordance in the findings of both modalities, with limb hypertrophy, and multiple haemangiomata – both subcutaneous and internally – demonstrated with ultrasound and MRI. The patient elected to terminate the pregnancy because of associated oligohydramnios and a small fetal chest noted at 20 weeks. The postmortem examination confirmed the antenatal diagnosis. Copyright © 2001 John Wiley & Sons, Ltd.     

长江,黄淮流域近期特大洪水预警和防洪形势

根据太阳黑子活动和长江，黄淮流域１８４０￣１９９４年历史和实测的洪水资料，推断在１９９７年及其前后，长江，黄淮流域很有可能出现一次特大的洪水。同时指出，目前长江、淮河、黄河的防洪形势不容乐观，必须及早采取对策，确保人民生命和财产的安全。     

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.