Nano-Tribological Study on a Super-Hydrophobic Film Formed on Rough Aluminum

A novel super-hydrophobic stearic acid (STA) film with a water contact angle of 166° was prepared by chemical adsorption on aluminum wafer coated with polyethyleneimine (PEI) film. The micro-tribological behavior of the super-hydrophobic STA monolayer was compared with that of the polished and PEI-coated Al surfaces. The effect of relative humidity on the adhesion and friction was investigated as well. It was found that the STA monolayer showed decreased friction, while the adhesive force was greatly decreased by increasing the surface roughness of the Al wafer to reduce the contact area between the atomic force microscope (AFM) tip and the sample surface to be tested. Thus the friction and adhesion of the Al wafer was effectively decreased by generating the STA monolayer, which indicated that it could be feasible and rational to prepare a surface with good adhesion resistance and lubricity by properly controlling the surface morphology and the chemical composition. Both the adhesion and friction decreased as the relative humidity was lowered from 65% to 10%, though the decrease extent became insignificant for the STA monolayer.

Creep characterization of a fiber reinforced plastic material

Creep behavior of [±45°]_s composite material is characterized by using uniaxial creep and recovery tests. The well-known Schapery nonlinear viscoelastic consti tutive relation was modified to make it suitable for characterizing the creep behavior of this material. Then, using this modified Schapery constitutive equation, by which the vis coplastic and creep damage can be taken into consideration, the creep behavior of [±45°]. glass fiber reinforced epoxy laminate was studied. The constitutive parameters of the material were determined experimentally, and the procedure and method of determination of the material parameters are proved to be valid.

Vertical sediment distribution

So far, various calculation models for the vertical distribution of suspended sediment concentration have been produced by several investigators from different theories. The limitations of all these models imply that it is possible to find a more reasonable model, for which each previous model can be included as special case. The formulation of a reasonable general model is the purpose of this paper.

非晶硅薄膜制备及其晶化特性研究

用磁控溅射法在K9玻璃上沉积了非晶硅（a—Si）膜和a—Si／Al膜，并将其在流动的N2气氛下进行退火。对退火前后的样品进行Raman光谱、XRD和SEM表征和分析。Raman光谱表明随着退火温度的升高，a-Si膜的散射峰出现了明显的蓝移，但XRD结果表明薄膜仍为非晶态；而a—Si／Al膜在温度很低时就已经开始晶化。

三种兰科植物的保护遗传学研究

本研究在野外调查的基础上，采用随机扩增多态DNA (RAPD)分析和形态学方法，研究了我国三种珍稀濒危兰科植物硬叶兜兰（Paphiopedilummicranthum）、麻栗坡兜兰（P. malipoense）和独花兰（Changnienia amoena）的遗传多样性与群体遗传结构，主要结果如下： 1．采用1 2个引物对分布于我国云贵地区的4个硬叶兜兰群体共161个体进行RAPD扩增和分析，得出物种水平的多态条带百分率（PPB）为71.6%，Nci的基因多样度(h)为0.217，Shannon多样性指数（1)为0.3301;4个群体的平均多样性水平为PPB=45.2%，h=0.1457，1= 0.2204：低于远交兰花的平均水平。分子方差分析(AMOVA)表明，在总遗传变异中，群体间遗传变异占20.31%．群体内占79.69%;POPGENE给出的基因分化系数 （Gst）为0.2958;遗传分化略高于远交物种的平均水平。空间自相关分析表明，所检测的两个群体中存在明显的空间结构，基因型在群体中以不同的小斑块存在。遗传距离和空间距离不存在相关关系。 2．用于麻栗坡兜兰的RAPD引物同上，但取样范围只有贵州的2个群体共10个个体。就所研究的个体柬看，麻栗坡兜兰的遗传多样性明显低于远交兰花物种的平均水平。物种水平上，多态条带百分率(PPB)为49.5%。Nei的基因多样度（h）为0. 1174， Shannon多样性指数(I)为0.1764：在群体水平上，上述三个指标的平均值则分别为12. 75%、0.0486和0.0712，均大大低于硬叶兜兰。然而，尽管作了种种努力，麻栗坡兜兰的取样个体数量仍很少，因此所得结果可能会有误差。 3．用16个引物对分布于河南、湖北、湖南、江西4个省11个独花兰群体共216个体进行了RA PD扩增和分析，独花兰在物种水平PPB=80. 7%，h=0.197．1=0. 3116;在群体水平，上述三个指标的平均值则分别为40. 9%、0.1247和0. 1902，均低于远交兰花的平均水平。AMOVA分析表明，11个独花兰群体间的遗传变异占43.48%，群体内的占56.52%：在神农架和新宁地区内部，群体间的遗传变异分别占13.68%和49.3g%(AMOVA)。POPGENE给出的11个群体的基因分化系数(Gst)为0.3580．神农架和新宁地区内的Gst，值分别为0.1194和0.2597。可见，群体间的遗传分化明显高于远交物种的平均水平。空间自相关分析表明，独花兰的遗传变异在群体内不存在明显的空间结构。群体之间的遗传距离和空间距离不存在相关关系。 4．对独花兰7个群体形态性状的分析发现，12个形态性状在群体内均有较高的变异性，cv值变动于0.022-0.30O。庐山群体(LS)在所有性状上的平均值均为最高。营养性状和花部性状的变异性基本一致。除花葶长和花距直径与某些花部性状之间没有显著的相关关系外，各性状之间均有显著的相关性。对XN4群体的统计没有发现假磷茎数目与其他性状之间存在显著相关性。 根据以上对硬叶兜兰、麻粟坡兜兰和独花兰遗传多样性和群体遗传结构韵研究，结合其他方面的资料;对三种兰花的濒危机制进行了初步的分析。首先，人为采挖和破坏是导致这些兰花物种濒危的直接原因，尤其是麻栗坡兜兰。其次， 适宜兰花生存的生境正在只益萎缩、退化和片段化。这两方面因素的共同作用导致上述兰花群体的数目和规模日益下降，由此引发的遗传多样性降低和遗传结构的改变进一步加剧其濒危状况。对于独花兰而言，较低的繁殖能力又使其生存状态雪上加霜。针对三个物种不同的繁殖特性和遗传学状况，提出如下保护措施。(1)硬叶兜兰由于繁殖能力较强、现存个体尚多，遗传多样性损失不甚严重，因此以保护其所在的生境为基础、实施原位保护，是比较合适的保护策略。(2)麻粟坡兜兰目前受破坏程度非常严重;所剩个体很少，遗传多样性较低，已经很难进行有效的原位保护。因此;应利用迁地保护手段抢救目前尚存的个体。(3)独花兰的繁殖能力较弱，因此在保护生境和严禁采摘的基础上，可采用人工授粉等方式，提高结实率、增加繁殖效率，促使其复壮：在进行迁地保护时，则应注意不同群体间存在较大遗传变异而群体内多样性较低这一现实。

云南贡山黄胡蜂属一新种

报道云南贡山黄胡蜂属Vespula 1 新种， 即贡山黄胡蜂Vespula gongshanensis, sp. nov.。模式标本保存在中国科学院昆明动物研究所。

南方某地产妇和婴儿体内多氯联苯蓄积水平的调查

目的了解我国南方某多氯联苯(PCBs)高暴露地区的产妇及其婴儿体内PCBs的蓄积水平。方法采集在当地某医院中符合条件的50对母婴对的母乳和脐带血,用GC-MS法进行PCBs含量的测定。结果母乳中13种PCBs总浓度的最大值为237 ng/g类脂,几何均数为138 ng/g类脂。脐带血中13种PCBs总浓度的最大值为102 ng/g类脂,几何均数为56.9 ng/g类脂。结论该地区妇女和婴儿体内普遍检测出较高水平的PCBs

河流生态系统健康及其评价

概括了河流生态系统健康概念的涵义 ,详细介绍了以着生藻类、无脊椎动物、鱼类为主要指示生物的河流生态系统健康的评价方法 ,并就其评价原理将这些方法分为预测模型法 (predictivemodels)和多指标法 (multimetrics两大类 ,提出了河流健康评价方法的发展方向 ,以及我国应尽快开展的研究工作 .

Actinomycetes and earthy-musty odorous compounds in brackish fishponds in Tianjin, China

The presence of the odorous compounds, 2-methylisoborneol (MIB) and geosmin, as well as causative microorganisms in brackish intensive cultivation fishponds in Tianjin, China that had a severe earthy-musty odor were evaluated. The results revealed that MIB was the primary odorous compound present in the Tianjin fishponds, with a concentration ranging from 0.53-5302.7 ng.L-1. Furthermore, the concentration of MIB was found to be closely correlated with the gross biomass of actinomycetes in the water, which ranged from 10.67-1528.24 x 10(6) cfu.ml(-1). Therefore, the sequences of the 16 SrRNA and morphological characteristics of the actinomycetes in the brackish fishponds were investigated. The results revealed that the actinomycetes in the brackish fishponds included 9 species of common and dominant actinomycetes belonging to 4 genera. Of these genera, Streptomyces were the dominant species, and Streptomyces, Nocardioides and Micromonospora were the most common species in the fishponds evaluated. Next, the ability of each of the isolated Streptomyces to produce MIB was measured under laboratory culture conditions. Streptomyces Sp2 was found to have a strong ability to produce MIB, which indicates that this strain may be the primary source of the earthy-musty odor reported in brackish intensive cultivation fishponds in Tianjin, China.

Si-based resonant-cavity-enhanced photodetector

We report one top-illumination and one bottom-illumination SiGe/Si multiple quantum-well (MQW) resonant-cavity-enhanced (RCE) photodetector fabricated on a separation-by-implanted-oxygen (SIMOX) wafer operating near 1300 nm. The buried oxygen layer in SIMOX is used as a mirror to form a vertical cavity with the silicon dioxide/silicon Bragg reflector deposited on the top surface. A peak responsivity with a reverse bias of 5 V is measured 10.2 mA/W at 1285 nm, a full width at half maximum of 25 nm for the top-illumination RCE photodetector, 19 mA/W at 1305 nm, and a full width at half maximum of 14 nm for the bottom-illumination one. The external quantum efficiency of the bottom-illumination RCE photodetector is up to 2.9% at 1305 nm, with a reverse bias of 25V. The responsivity of the bottom-illumination RCE photodetector is improved by two-fold compared with that of the top-illumination one. (C) 2001 Society of Photo-Optical Instrumentation Engineers.

带燃料均衡的空间多飞行器编队重构的轨道规划方法

航天任务需求的多样化对空间多飞行器编队重构的轨道规划问题不仅提出了燃料或时间最优的要求,还提出了燃料和时间最优以及燃料均衡的要求。将带燃料均衡的多飞行器编队重构的轨道规划建模为一个多目标优化问题,通过将进化计算与问题领域的知识相结合,提出了一种基于小生境进化算法的最优轨道规划方法。该方法能从变轨时间、燃料消耗和燃料消耗方差三方面分别评价一个变轨方案的最优性,并且一次规划能够提供多个Pareto最优变轨方案。仿真结果证明了该方法的正确性和有效性,还揭示了编队重构轨道规划问题的三个优化目标之间的关系,对于制定任务计划具有重要的参考价值.