Leaf area development, dry weight accumulation and solar energy conversion efficiencies of Phaseolus vulgaris L. under different soil moisture levels near Nairobi, Kenya

ＩｎｔｒｏｄｕｃｔｉｏｎＫｅｎｙａ○ｓｈｉｇｈｐｏｐｕｌａｔｉｏｎｇｒｏｗｔｈｒａｔｅｈａｓｃｒｅａｔｅｄｐｒｅｓｓｕｒｅｏｎｔｈｅｈｉｇｈｐｏｔｅｎｔｉａｌａｒｅａｓ．Ｔｈｉｓｈａｓｒｅｓｕｌｔｅｄｉｎｔｈｅｍｉｇｒａｔｉｏｎｏｆｐｅｏｐｌｅｔｏｕｎｃｕｌｔｉｖａｔｅｄ“ｍａｒｇｉｎａｌ”ｌａｎｄｓｗｈｉｃｈｍａｋｅｕｐａｂｏｕｔ８０％ｏｆｔｈｅｃｏｕｎｔｒｙａｎｄａｒｅｐｒｅｄｏｍｉｎａｎｔｌｙｏｆｌｏｗａｇｒｉｃｕｌｔｕｒａｌｐｒｏｄｕｃｔｉｖｉｔｙ（Ｈｏｒｎｅｔｚ，１９９０）．Ｔｈｅｓｅ…     

摩擦系数和材料参数对薄钢板胀形成形的影响

通过对胀形成形进行仿真计算和实际测试分析,比较了不同润滑条件下的应变分布,确定了胀形成形时的静摩擦系数μ值,研究分析了摩擦系数和材料参数n、r值对胀形成形的影响。     

不同空速下Pd/CeZrO_4/γ-Al_2O_3的起燃特性

以渍法制备了Pd/Ce0 ZrO4 /γ Al2 O3三效催化剂。在不同空速下 ,分别考察了空速对催化剂T30 % 、T50 % 、T90 % 的影响规律。详细分析了不同空速对催化剂起燃特性产生不同影响的原因所在。Pd/CeZrO4 /γ Al2 O3催化剂具有很好的起燃能力及空速特性。     

Zinc and lead sequestration in an impacted wetland system

The fate and bioavailability of pollutant metals is important to the long-term health of freshwater wetland systems, particularly in areas with elevated background levels of trace metals. Precipitation of some authigenic mineral phases in wetland sediments can potentially limit metal bioavailability through sequestration in low-solubility compounds, such as metal sulfides. Zinc and Pb concentrations were analyzed in water, plant and sediment samples taken from a metal-contaminated wetland in Chicago, IL, USA in order to assess metal fate and bioavailability, while X-ray absorption spectroscopy (XAS) studies were conducted to determine zinc speciation in the wetland sediments. The results showed sequestration of metal into the pond sediments, most likely in iron precipitate phases. In surface sediments, re-release of Zn and Pb into pore waters was correlated with microbial iron reduction, while the presence of sulfide in anoxic pore waters corresponded to decreased dissolved concentrations of both elements. Analysis of extended X-ray absorption fine structure (EXAFS) data confirmed that sulfide compounds dominated zinc speciation throughout the sediment. Uptake of trace metals in Phragmites plants was limited primarily to plant roots, while concentrations of both Pb and Zn in aquatic vegetation were significantly elevated, representing a potential bioaccumulation hazard.     

石墨炉原子吸收法测定样品中的砷

石墨矿原子吸收分光光度法测定样品中的砷含量具有简便、快速、试剂用量少、样品直接测定等优点,精密度1.8%,检出限0.003,均优于其他分析方法.     

High resolution proton NMR spectroscopy of human amniotic fluid

Human amniotic fluid (HAF) is a dynamic system whose characteristics depend on continuous interchanges between fetal and maternal circulations. HAF reflects not only the environment of the fetus but may also provide information about fetal development or pathology. The concentration of HAF constituents varies with gestational age and pathological states. The number of the compounds currently implicated in fetal developmental pathology are relatively few. Currently used assay methods are not adequate to totally explain or predict the complex biochemistry of the fetus. The purpose of this work was to investigate HAF with NMR spectroscopy. In the present study HAF was obtained from 47 women undergoing routine amniocentesis. Cells were separated for karyological analysis and the supernatant was acid-extracted, lyophilized and re-suspended in D₂0 resulting in a concentration increase over native fluid. ¹H NMR spectra were obtained at 360 MHz and 60 MHz. Eighteen compounds including several amino acids, were identified using parallel reference and standard addition protocols. NMR spectroscopy detected compounds of known clinical importance including glucose, leucine, isoleucine, lactate and creatinine. In conclusion, we have demonstrated that a number of physiologically relevant compounds are readily observable in HAF using ¹H NMR spectroscopy. This technique can currently provide valuable information regarding HAF composition and has the potential of being used in vivo in the future.     

高比表面积活性炭(HSAAC)对水中镉(Ⅱ)吸附性能的研究

以石油焦基为原料,采用KOH活化法制取高比表面积活性炭.考察了高比表面积活性炭吸附水中Cd(Ⅱ)时,pH值、Cd(Ⅱ)浓度、吸附时间和活性炭用量等因素对Cd(Ⅱ)吸附量和水中Cd(Ⅱ)残余浓度的影响.实验结果表明高比表面积活性炭在适宜条件下对Cd(Ⅱ)具有较大的吸附量和良好的再生效果.为HSAAC在废水中的实际应用提供了理论依据.     

原子吸收分光光度法测定水中锌的不确定度评定

参照JJF1059-1999<测量不确定度评定与表示>的技术规范,通过对原子吸收分光光度法测定水质Zn标准样品过程的分析,阐明了Zn测量不确定度的评定步骤和评定方法,归纳提出了影响水样中Zn测量不确定度的主要因素和不确定度分量的主要来源,并给出了相对标准不确定度分量,得出了该Zn标准样品测量不确定度的评定结果:扩展不确定度为U=0.012mg/L,或相对不确定度为3.5%.结论:评定程序和方法符合技术规范要求,操作简便、结果可靠,有较高的应用价值.     

新型防冻抑尘剂性能研究

在对CMl、CM2型防冻抑尘剂的抗冻性能、在自然环境中昼夜周期吸湿和放湿的行为进行了测定的基础上．为提高性能，对这两种防冻抑尘进行了复配。其研究结果对卤化物抑制路面、地面和各种散体堆放场的扬尘具有实际意义。     

飞机草处理含铅废水的应用研究

用飞机草吸附废水中的铅离子，研究中探讨了影响吸附的主要参数，包括飞机草投加量、初始浓度、震荡时间、pH和温度。结果显示：用飞机草来吸附废水中的重金属离子，可以有效去除里面的铅离子，然后富集，重新得到金属达到废物利用、变废为宝的目的。