An elastoplastic constitutive relation of whisker-reinforced composite for meso damage: Part I - formulation

An elastoplastic constitutive relation is developed for meso damage of whisker-reinforced composites. A model is constructed that includes orientation distribution of whiskers and slip systems as well as interface and crystal sliding. Evolution of damage will be addressed. Given in Part I is the formulation while examples will be illustrated in Part II.

星间激光通信光束微弧度跟瞄性能检测装置的设计原理

基于矢量折射定理，研究了透射光束通过双棱镜实现微弧度量级偏转的设计原理，解决了星间激光通信精跟瞄检测的难题。推导了正交双棱镜实现光束偏转的精确公式，提出以水平张角和垂直张角表达光束视场，并说明了单棱镜实现光束偏转的一般情况。根据设计指标和计算结果确定了棱镜的主要参量，进而对光束的偏转结果进行了数值模拟。最后的实验结果与模拟结果基本一致。结果表明：取棱镜棱角α为4°时，棱镜每旋转1’，透射光束变化约1μrad；分别控制双棱镜在其最小偏向角一侧小角度偏转，可以实现光束在水平方向和垂直方向500μ范围内的精确扫

Double-line-density gratings structure for compression and generation of double femtosecond laser pulses

Grating pairs are widely used for pulse compression and stretching. Normally, the two gratings are identical. We propose a very simple structure with double-line-density reflective gratings for pulse compression and generation of double pulses, which has the advantages of no material dispersion, compact in volume, simple in structure, etc. The use of reflective Dammann gratings fully demonstrated the principle of this structure. The output pulses are well verified by a standard frequency-resolved optical gating apparatus. This structure will be highly interesting in ultrashort pulse compression and other more practical applications of femtosecond laser pulses. (c) 2007 Optical Society of America.

Effects of Yb concentration on the fluorescence spectra of Yb-doped YAlO3 single crystals

0.5 at.% Yb:YAlO3(YAP), 5 at.% Yb:YAP and 15 at.% Yb:YAP were grown using the Czochralski method. Their absorption and fluorescence spectra were measured at room temperature and their emission line shape was calculated using the method of reciprocity. It was observed that the fluorescence spectra changed appreciably with the increasing of Yb concentration. For 0.5 at.% Yb:YAP, the line shape of fluorescence is very similar with the calculated emission line shape; with the increasing of Yb doping concentration, the line shape of fluorescence is very different from the calculated emission line shape. These phenomena are caused by the strong self-absorption at 979 and 999 nm for Yb:YAP. (c) 2005 Elsevier B.V. All rights reserved.

甜菜碱提高植物光合作用对逆境抗性机理的研究

从菠菜中克隆甜菜碱醛脱氢酶( betaine aldehyde dehydrogenase，BADH)基因并转化烟草， 研究转基因烟草光合作用对高温和盐胁迫等环境胁迫的抗性机理，利用外源甜菜碱研究在正常条件下对植物光合作用的影响以及在盐胁迫下外源甜菜碱对玉米幼曲光合作刚的保护机理。主要结果如下： 转BADH基因烟草中能合成甘氨酸甜菜碱，合成的甜菜碱主要积累于叶绿体中。转BADH 基因烟草提高了对高温胁迫的抗性，在中度高温胁迫下，转基冈烟草生长利光合作用对高温 的抗性增强。中度高温胁迫下，转基冈烟草光合作用的维持是由于甜菜碱对Rubisco活化酶的保护作用。在中度高温胁迫下甜菜碱通过维持Rubisco活化酶的活化态以及阻止Rubisco 活化酶山可溶性问质向类囊体的聚集，从而维持了Rubisco活化酶的活性，进而维持了C02 的同化。在严重高温胁迫下，烟草光系统II受到影响，转BADH基冈烟草通过提高体内抗氧化酶系统的功能，减轻了高温胁迫对光合机构造成的活性氧伤害，高温胁迫下转基因烟草体内抗氧化酶如SOD、APX、GR等酶活性明显高于野生型。在高温胁迫下，证明了甜菜碱对光系统II的保护作用主要在氧化侧，严重高温胁迫下，转基因烟草维持较高的PSII活性。 转BADH基因烟草提高了对盐胁迫的抗性，盐胁迫下转基因烟草光合作用的维持与盐胁迫下转基因烟草较高的气孔导度和抗氧化酶活性的提高有关。 外源甜菜碱在正常的非胁迫条件下对植物的生长有促进作用，而这一作用与光合速率的提高有关。通过对气孔导度、光合碳同化关键酶以及叶绿素荧光分析证明，甜菜碱对光合作用的促进与气孔导度的提高有关，同时甜菜碱提高了光系统ll的实际光化学效率。 外源甜菜碱提高了盐胁迫条件下植物的抗性，抗盐性的提高与盐胁迫下甜菜碱对气孔导度的提高以及维持较高的光系统II光化学活性有关。

梭鱼的分子系统地理学研究——晚更新世西北太平洋边缘海隔离分化及其有限的扩散能力

下载PDF阅读器西北太平洋具有独特的板块特征和地质历史,几个边缘海将亚洲大陆和太平洋隔开.在更新世冰期的低海平面时期,海洋生物群体可能会被隔离在日本海、东海和南海.伴随冰后期海平面的上升,以往的研究认为被隔离在3个边缘海的群体会因为扩散的作用而重新混匀.为了检验该假说,本研究探讨了梭鱼的系统地理格局.采集梭鱼分布范围内9个地点的272个梭鱼个体,分析其线粒体控制区5'端435 bp的片段.共检测到3个不同的单倍型类群,这3个单倍型类群可能是在更新世冰期被隔离在3个边缘海内而产生的分化.这一研究结果与以往的假设相反,3个单倍型类群在地理上的频率分布存在很大差异.分子方差分析和群体多样性指数都表明3个边缘海内的梭鱼群体间存在显著的遗传差异.这些结果表明:与基于生物学特性预期的梭鱼具有较高的扩散能力相反,梭鱼群体空间上的基因交流是很有限的.东海的梭鱼群体间缺乏系统地理格局,这可能是因为末次冰盛期后梭鱼群体发生了近期的栖息地扩张,群体间没有足够的进化时间在迁移-漂变间取得平衡.

Anti Human Immunodeficiency Virus Type 1 (HIV-1) Agents 4. Discovery of 5,5 '-(p-Phenylenebisazo)-8-hydroxyquinoline Sulfonates as New HIV-1 Inhibitors in Vitro

To search for compounds with superior anti-human immunodeficiency virus type 1 (HIV-1) activity, ten 5,5'-(p-phenylenebisazo)-8-hydroxyquinoline sulfonates (4a-j) were synthesized and preliminarily evaluated as HIV-1 inhibitors in vitro for the first time. Some compounds demonstrated anti-HIV-1 activity, especially 5,5'-(p-phenylenebisazo)-8-hydroxyquinoline p-ethylbenzenesulfonate (4g) and 5,5'-(p-phenylenebisazo)-8-hydroxyquinoline p-chlorobenzenesulfonate (41) showed the more potent anti-HIV-1 activity with 50% effective concentration (EC50) values of 2.59 and 4.01 mu g/ml, and therapeutic index (TI) values of 31.77 and 24.51, respectively.

滤食性鲢、鳙肠含物PCR-DGGE指纹分析

以采自武汉东湖的滤食性鲢、鳙为对象,通过PCR-DGGE并结合序列分析对其肠道微生物及肠含物中残留的食物组分进行了探索研究。在所有个体中都能检测到不同的PCR-DGGE指纹谱带,其中包括肠道细菌在内的原核谱带较多,真核谱带相对较少;分析结果表明针对鲢、鳙肠含物这一特殊生境样品进行PCR-DGGE指纹分析是可行的。PCR-DGGE指纹结构及针对部分特定PCR-DGGE谱带的序列分析显示,从武汉东湖采集的鲢、鳙在食性上存在很大的重叠,并没有像基于常规食性分析文献报道的那样明显不同。基于肠含物DNA来进行鱼类食

缓步动物门三新种及一新记录种记述(英文)

记述了得自云南省和河南省苔藓与丝状绿藻中的缓步动物门三新种和一新记录种 :异缓步纲棘影熊虫科的西藏角棘影熊虫新记录种Cornechiniscustibetanus (Maucci,1 979)和石林假棘影熊虫 ,新种Pseudechiniscusshilinensissp .nov.;真缓步纲大生熊虫科的河南趾生熊虫 ,新种Dactylobiotushenanensissp .nov .;高生熊虫科的昆明高生熊虫 ,新种Hypsibiuskunmingensissp .nov .。

Phylogenetic relationships of glyptosternoid fishes (Siluriformes : Sisoridae) inferred from mitochondrial cytochrome b gene sequences

To explore phylogenetic relationships among glyptosternoid fishes, we determined nucleotide sequences of the complete mitochondrial cytochrome b gene region (1138 base pair). Thirteen species of glyptosternoid fishes and six species of non-glyptosternoids represent 10 sisorid genera were examined. Molecular phylogenetic trees were constructed using the maximum parsimony, minimum evolution, maximum likelihood, and Bayesian methods. Bayesian and maximum likelihood analyses support the monophyly of glyptosternoids, but our hypothesis of internal relationships differs from previous hypothesis. Results indicated that glyptosternoid is a monophyletic group and genera Glyptosternum and Exostoma are two basal species having a primitive position among it. Genera Euchiloglanis and Pareuchiloglanis form a sister-group. Then they form a sister-group with Pseudexostoma plus Oreoglanis. Our result also found that Pareuchiloglanis anteanalis might be considered as the synonyms of Parechiloglanis sinensis, and genus Euchiloglanis might have only one valid species, Euchiloglanis davidi. (C) 2003 Elsevier Inc. All rights reserved.

Mn-AlInN: a new diluted magnetic semiconductor

Mn ions have been incorporated into MOCVD grown Al1-x In (x) N/GaN thin films by ion implantation to achieve the room temperature ferromagnetism in the samples. Magnetic characterizations revealed the presence of two ferromagnetic transitions one has Curie points at similar to 260 K and the other above room temperature. In-diffusion of indium caused by the Mn implantation leads to the partition of AlInN epilayer into two diluted magnetic semiconductor sub-layers depending on the Mn concentration. The Curie temperature of 260 K is assigned to the layer having lower concentration, whereas T (c) above room temperature is assumed to be associated to the layer having higher Mn concentration.

Single-mode behaviour judgment of optical waveguides by imaginary-distance beam propagation method under perfectly matched layer boundary condition

Imaginary-distance beam propagation method under the perfectly matched layer boundary condition is applied to judge single-mode behaviour of optical waveguides, for the first time to our knowledge. A new kind of silicon-on-insulator-based rib structures with half-circle cross-section is presented. The single-mode behaviour of this kind of waveguide with radius 2mum is investigated by this method. It is single-mode when the slab height is not smaller than the radius.

Application of rapid thermal annealing on 1.3-1.55 mu m GaInNAs(Sb) lasers grown by molecular beam epitaxy

Rapid thermal annealing (RTA) has been demonstrated as an effective way to improve the crystal quality of GaInNAs(Sb) quantum wells (QWs). However, few investigations have been made into its application in laser growth and fabrication. We have fabricated 1.3 mu m GaInNAs lasers, both as -grown and with post-growth RTA. Enhanced photoluminescence (PL) intensity and decreased threshold current are obtained with RTA, but the characteristic temperature T-o and slope efficiency deteriorate. Furthermore, T-o has an abnormal dependence on the cavity length. We attribute these problems to the deterioration of the wafer's surface. RTA with deposition Of SiO2 was performed to avoid this deterioration, T-o was improved over the samples that underwent RTA without SiO2. Post-growth and in situ annealing were also investigated in a 1.55 mu m GaInNAsSb system. Finally, continuous operation at room temperature of a GaAs-based dilute nitride laser with a wavelength over 1.55 mu m was realized by introducing an in situ annealing process. (c) 2007 Elsevier B.V. All rights reserved.