Strain Rate-Dependent Compressive Deformation Behavior of Nd-Based Bulk Metallic Glass

Compressive deformation behavior of the Nd60Fe20Co10Al10 bulk metallic glass was characterized over a wide strain rate range (6.0 x 10(-4) to 1.0x10(3) s(-1)) at room temperature. Fracture stress was found to increase and fracture strain decrease with increasing applied strain rate. Serrated flow and a large number of shear bands were observed at the quasi-static strain rate (6.0 x 10(-4)s(-1)). The results suggest that the appearance of a large number of shear bands is probably associated with flow serration observed during compression; and both shear banding and flow serration are a strain accommodation and stress relaxation process. At dynamic strain rates (1.0 x 10(3) s(-1)), the rate of shear band nucleation is not sufficient to accommodate the applied strain rate and thus causes an early fracture of the test sample. The fracture behavior of the Nd60Fe20Co10Al10 bulk metallic glass is sensitive to strain rate.

Influence of Electrostatic Interaction on Fibrinogen Adsorption on Gold Studied by Imaging Ellipsometry Combined with Electrochemical Methods

Imaging ellipsometry was combined with electrochemical methods for studying electrostatic interactions of protein and solid surfaces. The potential of zero charge for gold-coated silicon wafer/solution interfaces wad determined by AC impedance method. The potential of the gold-coated silicon wafer was controlled at the potential of zero charge, and the adsorption of fibrinogen on the potential-controlled and non-controlled surfaces was measured in real time at the same time by imaging ellipsometry The effect of electrostatic interaction was studied by comparing the difference between the potential of controlled adsorption and the Potential of noncontrolled adsorption. It was shown that the rate of fibrinogen adsorption on the potentiostatic surface was faster than that on the nonpotentiostatic surface. The electrostatic influence on fibrinogen adsorption on the gold-coated silicon wafer was weak, so the hydrophobic interaction should be the major affinity.

高温下CF_4在H_2中解离的反应动力学研究

用单脉冲激波管研究了有少量ＣＦ３Ｃｌ参予下的ＣＦ４与Ｈ２的混合物在高温下的反应动力学，发现主要产物为Ｃ２Ｆ４和ＣＦ３Ｈ．对实验结果的分析表明，反应过程为一个双中心链反应。始发反应为ＣＦ３Ｃｌ的Ｃ—Ｃｌ键的断裂，继之以由Ｈ２和ＣＦ４为媒介的双中心链传递，最后测得温度由１０００至１０８０Ｋ，压力为０．１ＭＰａ下的ＣＦ４表观分解速率常数为Ｋｅｆｆ＝１０１３．７ｅｘｐ（－５５０００／ＲＴ）１１／２ｍｏｌ－１ｓ－１对这一结果进行分析，得到以下相关的反应速度常数ｋ（ＣＦ３Ｃｌ→ＣＦ３＋Ｃｌ?）＝１０１５ｅｘｐ（－８１０００／ＲＴ）ｓ－１ｋ（ＣＦ３＋Ｈ２→ＣＦ３Ｈ＋Ｈ?）＝１０８．６ｅｘｐ（－８８００／ＲＴ）１?ｍｏｌ－１?ｓ－１ｋ（ＣＦ４＋Ｈ?→ＣＦ３?＋ＨＦ）＝１０１１．４ｅｘｐ（Ｇ２００００／ＲＴ）１?ｍｏｌ－１?ｓ－１ｋ（ＣＦ３?＋Ｈ?→ＣＦ３Ｈ）＝１０８．０１?ｍｏｌ－１?ｓ－１

Fuzzy inferring mathematical morphology and optical implementation

Fuzzification is introduced into gray-scale mathematical morphology by using two-input one-output fuzzy rule-based inference systems. The fuzzy inferring dilation or erosion is defined from the approximate reasoning of the two consequences of a dilation or an erosion and an extended rank-order operation. The fuzzy inference systems with numbers of rules and fuzzy membership functions are further reduced to a simple fuzzy system formulated by only an exponential two-input one-output function. Such a one-function fuzzy inference system is able to approach complex fuzzy inference systems by using two specified parameters within it-a proportion to characterize the fuzzy degree and an exponent to depict the nonlinearity in the inferring. The proposed fuzzy inferring morphological operators tend to keep the object details comparable to the structuring element and to smooth the conventional morphological operations. Based on digital area coding of a gray-scale image, incoherently optical correlation for neighboring connection, and optical thresholding for rank-order operations, a fuzzy inference system can be realized optically in parallel. (C) 1996 Society of Photo-Optical Instrumentation Engineers.

部分端面抽运板条激光器腔镜倾斜问题研究

部分端面抽运的板条激光器是一种新型固体激光器．配合混合腔可以实现在大功率下保持高光束质量的激光振荡输出。谐振腔的腔镜倾斜是影响激光器输出特性的重要因素，快速傅里叶方法是一种快捷有效的计算方法，利用此方法模拟了腔镜倾斜对近场相位分布和远场光强分布的影响，并分析了光束质量的变化。理论分析表明，腔镜的小角度倾斜对近场相位影响较大，但对远场光强空间分布影响不大；随着倾斜角度不断增大，远场发散角和光束腰宽度也增大，光束质量虽然存在恶化的趋势，但光束质量因子肝值仍然较小，离轴非稳腔仍能保持高光束质量的输出。

铒玻璃在1．54μm实现1 Hz下3 J和5 Hz下0．6 J的激光输出

近年来,随着激光告警、激光指示、风速测量、激光雷达尤其是激光美容等方面的需求逐渐增加,要求掺铒激光玻璃能够实现比以往更高重复频率以及更大能量的激光输出,其中对脉冲能量的要求达1～10 J。

深圳湾两种引种海桑属红树植物的竞争关系

红树林是生长在热带亚热带低能海岸潮间带的一种特殊的生态系统，它是海岸生态关键区。近年来由于人为的破坏，我国红树林面积日益减少，面临濒危的境地。红树林生态系统的恢复和可持续发展成为了有关研究人员和组织的焦点。引种是红树林恢复最重要的手段。无瓣海桑和海桑作为很有发展前景的红树林造林树种，已经成为了东南沿海一带主要的引种红树种。 海桑和无瓣海桑具有很多相似的特征，在生产实践中往往同时被引种到同一生境中。为了比较两个种之间的生长趋势以及相互作用关系，本实验采用替代序列设计，对无瓣海桑（Sonneratia apetala）和海桑（S. caseolaris）的竞争进行了研究，于2005年8月~2007年8月期间对无瓣海桑和海桑的形态学指标、生理学指标以及营养元素的分配进行了连续测定，采用多个竞争系数评估两个种的竞争。结果表明： 1. 在生物量及其它形态学指标的测定中，海桑比无瓣海桑具有显著的优势，说明海桑具有更强的生长优势，对深圳湾的生境更加适应。通过对无瓣海桑和海桑竞争系数的计算，发现无瓣海桑和海桑之间存在对相同资源的竞争，海桑的相对竞争能力比无瓣海桑强，而受到的竞争抑制小于无瓣海桑。 2. 海桑的净光合速率显著高于无瓣海桑，同时无瓣海桑在混种情况下具有较低的净光合速率，说明种间竞争对无瓣海桑的光合作用产生抑制作用。同时，种间竞争也对无瓣海桑的水分利用效率、光合N利用效率产生了抑制作用，但两个种之间的蒸腾速率差异不显著。 3. 植物光合叶片的N含量水平越高，叶片的净光合速率、水分利用效率和光合N利用效率越高，而光合叶片的C/N值越低。海桑在营养元素吸收和积累方面具有优势，进一步解释了海桑的竞争机制。 在深圳湾，引入种海桑比无瓣海桑具有更强的竞争力。加强对海桑属外来种的研究是很有必要的，特别是对海桑的研究，应该受到更多的关注。而对于海桑属外来种是否能引起生物入侵，还需要进一步的研究。

我国西南地区珍稀濒危动物的进化和保护遗传学研究

中国西南地区分布有许多重要的珍稀濒危动物，对它们的保护举世瞩目，其中一些动物的分类进化地位还存在着争议。我们实验室多年来致力于这些物种的进化遗传和保护遗传学研究，旨在阐明这些物种的进化地位，确定野生或圈养群体的遗传结构，为制定科学的保护计划提供不可缺少的遗传学资料。

An antimicrobial peptide with antimicrobial activity against Helicobacter pylori

An antimicrobial peptide named odorranain-HP was identified from skin secretions of the diskless odorous frog, Odorrana grahami. It is composed of 23 amino acids with an amino acid sequence of GLLRASSVWGRKYYVDLAGCAKA. By BLAST search, odorranain-HP had si

贵州绵羊线粒体DNA (m tDNA ) 多态性研究

采用15 种限制性内切酶对贵州威宁绵羊和六盘水绵羊各5 只个体的m tD2 NA 多态性进行研究。其中只有BamHÉ 一种酶的酶切类型表现多态, 产生三种酶切 类型。共得到17 种限制性态型, 可归结为三种m tDNA 单倍型, 在威宁绵羊中单倍 型É 所占比较较大(80% ) , 单倍型Ë 只占20% , 而在六盘水绵羊中则单倍型É 和Ê 所占比例相当; 根据单倍型在群体中的分布和单倍型间遗传距离, 推测贵州绵羊的 m tDNA 单倍型É 和Ê 可能代表两个母系祖先的基本单倍型, 其分化时间约有16～ 32 万年之久, 单倍型Ë 则可能是由单倍型É 随机突变而来; 两个地方绵羊群体间的 分化时间大约为613～ 1216 万年, 群体间的m tDNA 遗传多态度较低, 但六盘水绵羊 群体内遗传多态度比威宁绵羊较丰富。

抗胸腺细胞抗体对中华鳖免疫系统的影响

国家自然科学基金(No.30070588;No.30371091)

Cytotoxicity evaluation of three pairs of hexabromocyclododecane (HBCD) enantiomers on Hep G2 cell

Hexabromocyclododecanes (HBCDs) are additive brominated flame retardants mainly used in plastics and textiles. At the present time, these compounds are found in almost all environmental and human samples. In order to evaluate the environmental safety and health risk of HBCDs, the enantiomerically pure alpha-, beta-, and gamma-HBCD were prepared using high performance liquid chromatography (HPLC) on a PM-P-CD column and the cytotoxicities of their enantiomers were evaluated in Hep G2 cells. Results from the 3-(4,5-dimethylthioazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), resazurin reduction and lactate dehydrogenase (LDH) release assays showed a good agreement that the order of cytotoxicity was gamma-HBCD >= beta-HBCD > alpha-HBCD, and that significantly lower cell viability and higher LDH release were observed in all (+)-enantiomers ((+) alpha-, (+) beta- and (+) gamma-HBCD) than the corresponding (-)-forms ((-) alpha-, (-) beta- and (-) gamma-HBCD). Additionally, the formation of reactive oxygen species (ROS) induced by these HBCD enantiomers were detected. The positive correlation between the LDH release and ROS formation demonstrated that the toxic mechanism might be mediated by oxidative damage. These results suggest that environmental and human health risks of HBCDs must be evaluated at the level of individual enantiomers. (C) 2008 Published by Elsevier Ltd.