Simplified method for determining cadmium concentrations in rice foliage and soil by using a biosensor kit with immunochromatography

BACKGROUND: The behavior of cadmium in ecosystems needs to be monitored because of the human toxicity of this heavy metal. The need recently arose for a simple and quick on‐site test for trace levels of Cd in food and environmental samples. In response, an immunochromatographic assay kit for detecting Cd was manufactured by Kansai Electric Power Co. of Japan. This kit uses the antigen–antibody complex reaction between the Cd–EDTA complex and an anti‐Cd–EDTA antibody and shows the results in terms of the degree of color developed on a test paper. We previously reported the successful use of this kit to determine Cd concentrations in brown rice. Here, we applied the kit to the determination of Cd concentrations in rice foliage and soil. RESULTS: Cadmium in rice foliage was not extracted successfully by the method used for brown rice. However, it was successfully extracted by 0.1 mol L^?1 HCl solution at a rice foliage:HCl ratio of 1:20, and coexisting metals were removed sufficiently by the column treatment. The Cd concentrations determined by immunochromatographic assay were well correlated with the values obtained by acid decomposition and inductively coupled plasma mass spectrometry. The 0.1 mol L^?1 HCl‐extractable Cd concentration in soil was also determined successfully with the kit. CONCLUSION: Approximate Cd concentrations in rice plants and 0.1 mol L^?1 HCl‐extractable Cd concentrations in soil can be monitored easily and quickly by this method at locations where facilities for acid digestion and precision analysis are not available. Copyright © 2009 Society of Chemical Industry     

Rational approach for the analysis of segmental reinforced soil walls based on kinematic constraints

The paper presents an analytical method for the solution of reinforced soil walls in which the wall facing has a structural role. The three-component (soil–reinforcement–wall) system is statically indeterminate, and hence cannot be solved by equilibrium equations alone. The paper follows up on the work of Baker and Klein [2004. An integrated limiting equilibrium approach for design of reinforced soil retaining structures part I – formulation. Geotextiles and Geomembranes 22, 119–150] where an interaction model, incorporating factors that divide forces between the reinforcement layers and the wall, was introduced to solve the statically indeterminate system. In the current work, the division factors are resolved such that the kinematic constraints of compatibility between the reinforcement layers and the wall are satisfied. This is achieved by solving an optimization problem in which the objective function includes the relative displacement between the reinforcement layers and the wall. The resultant system is fully coupled whereby upper reinforcement layers are affected by the behavior of lower layers. As such, the method overcomes the limitation of the original framework in which the top-down procedure omits such coupling. A non-dimensional parametric study was conducted on walls with 10 face blocks (9 reinforcement layers). Results are given in a normalized manner for cases in which the reinforcement pullout stiffness is uniform and linearly increasing with depth. Analysis results show that in cases where the wall is relatively stiff compared to the reinforcement, the upper reinforcement layers are clearly affected by the lower layers (this is a direct outcome of the fully coupled system). On the other hand, when the relative stiffness of the wall is low, the system behavior tends towards that of a hinged system, which is statically determinate. In this case the solution becomes independent of the reinforcement pullout stiffness. Analysis results indicate that current design codes, which do not explicitly consider the structural role of the facing in the calculation procedure, may be overconservative in certain cases. This result supports the argument for introducing the structural role of the facing into design procedures.     

粉喷桩处理铁路软土地基施工工艺及质量控制

结合武襄铁路增二线站前Ⅳ标段中铁三局五公司二工区管段内粉喷桩处理软土地基工程，对其施工工艺、主要施工质量控制手段及检测技术进行了论述，为今后同类工程中软基处理提供了宝贵经验。     

季节性冻土深基坑支护技术研究

通过对中国地质大学(北京)综合游泳馆工程拟建场地土层的土质、深度及基坑深度的分析与比较,确定出基坑深度范围内土层的土质。介绍了季节性冻土深基坑支护经常出现的问题,并分析了这些问题出现的原因。对常用土钉支护方法在季节性冻土深基坑支护中运用的局限性做了总结,最后提出一种改进的土钉支护方法。该法针对冻土发生冻融循环时冻胀与融沉的特点采取了相应的控制措施,从而保证了季节性冻土深基坑的稳定性。该法操作简单可行,实践证明效果明显。     

Effect of exposure time on the morphology of corrosion on high chromium white cast iron in high temperature caustic solutions

High chromium white irons are important candidate materials for use in alumina refineries to combat wear and corrosion. The effect of exposure time on the formation of oxide films was studied in a 23% Cr white cast iron exposed at 260 °C in 110 g/l caustic soda solutions. It was found that whilst well‐formed octahedral M(II)O.M(III)₂O₃ spinel type oxides initially formed and spread across the surface of the material, these were gradually replaced by a background oxide with a higher Cr/Fe ratio and the morphology of the octahedral crystals became less well formed. Also, the oxidation was found to be predominantly in the matrix material, leaving carbide particles unsupported on the surface and in the later stages, significant corrosion was found along the carbide/matrix phase boundary.     

成形路基地基沉降处理探讨

通过对已填筑路基沉降异常事例的分析论证,提出了水泥旋喷桩注浆的处治方案,并详细介绍了具体工艺及应注意事项,解决了路基变形而引发的沉降问题,为今后同类路基沉降治理工程提供了经验和指导。     

化学聚合物和膨润土组合泥浆的应用

上海临港某工程通过使用化学聚合物和膨润土组合泥浆,有效的解决了在厚层粉土中灌注桩常见的坍孔、扩径等问题,可供类似工程借鉴参考.     

单片机在节水灌溉系统中的应用

介绍了基于单片机的节水灌溉控制系统的方案设计,工作原理,硬件电路和软件设计.实践证明,该系统具有成本低、运行可靠、可扩展性好等特点,有广泛的应用价值和前景.     

砂性土路基施工工艺探讨

对京津（北京—天津）高速公路砂性土路基施工土质的特点和施工性能、影响压实的因素进行试验分析,针对性的采取不同施工措施,通过施工工艺、方法的改善,实现质量控制,并重点论述冲击碾压施工工艺在施工中的应用及作用。