Squeeze-film Effects in MEMS Devices with Perforated Plates for Small Amplitude Vibration

Squeeze-film effects of perforated plates for small amplitude vibration are analyzed through modified Reynolds equation (MRE). The analytical analysis reckons in most important influential factors: compressibility of the air, border effects, and the resistance caused by vertical air flow passing through perforated holes. It is found that consideration of air compressibility is necessary for high operating frequency and small ratio of the plate width to the attenuation length. The analytical results presented in this paper agree with ANSYS simulation results better than that under the air incompressibility assumption. The analytical analysis can be used to estimate the squeeze-film effects causing damping and stiffness added to the system. Since the value of Reynolds number involved in this paper is low (< 1), inertial effects are neglected.

The interaction between poly(vinylpyrrolidone) and reversed micelles of water/AOT/n-heptane

The interactions between poly(vinylpyrrolidone) (PVP) and the reversed micelles composed of water, AOT, and n-heptane are investigated with the aid of phase diagram, measurements of conductivity and viscosity, Fourier transform infrared (FTIR) spectrum, and dynamic light scattering (DLS). The phase diagrams of water/AOT/heptane in the presence of and absence of PVP are given. The conductivity of the water/AOT/heptane reversed micelle without PVP initially increases and then decreases with the increase of water content, ω0 (the molar ratio of water to AOT), while the plots of conductivity (K) versus ω0 of the reversed micelle in the presence of PVP depend on the PVP concentrations. The plot of K versus ω0 with 2.0%wt PVP is similar to that without PVP. Only the ω0,max (the water content that the maximum conductivity corresponds to) is larger than that without PVP. Nevertheless, the conductivity of the reversed micelle containing more than 4%wt PVP always rises with the increase of the water content in the measured range. The DLS results indicate that the hydrodynamic radius (Rh) in the presence and absence of PVP rises with the increase of ω0. The plots with PVP and without PVP have almost the same value when ω0<17; and after that, it quickly increases with the increase of ω0. It is interesting to find that there is almost no effect of the PVP concentration on the viscosity and Rh of the reversed micelle at ω0 = 15. The FTIR results suggest that the contents of SO3--bound water and Na+-bound water both decrease with PVP added, while the content of the bulky-like water increases. However, the trapped water in the hydrophobic chain of the surfactant is nearly unaffected by PVP. It is also found from the FTIR that the carbonyl group stretching vibration of AOT is fitted into two sub-peaks, which center at 1740 and 1729 cm-1, corresponding to the trans and cis conformations of AOT, respectively.

Three-dimensional coupled wave study for finite-sized anisotropic volume holographic gratings under ultrashort pulsed beam readout

The three-dimensional coupled wave theory is extended to systematically investigate the diffraction properties of finite-sized anisotropic volume holographic gratings (VHGs) under ultrashort pulsed beam (UPB) readout. The effects of the grating geometrical size and the polarizations of the recording and readout beams on the diffraction properties are presented, in particular under the influence of grating material dispersion. The wavelength selectivity of the finite-sized VHG is analyzed. The wavelength selectivity determines the intensity distributions of the transmitted and diffracted pulsed beams along the output face of the VHG. The distortion and widening of the diffracted pulsed beams are different for different points on the output face, as is numerically shown for a VHG recorded in a LiNbO3 crystal. The beam quality is analyzed, and the variations of the total diffraction efficiency are shown in relation to the geometrical size of the grating and the temporal width of the readout UPB. In addition, the diffraction properties of the finite-sized and one-dimensional VHG for pulsed and continuous-wave readout are compared. The study shows the potential application of VHGs in controlling spatial and temporal features of UPBs simultaneously. (C) 2007 Optical Society of America

Kilohertz electro-optic Q-switched Nd : YAG ceramic laser

We investigate the lasing characteristics of a laser-diode-array side-pumped electro-optic Q-switched Nd:Y3Al5O12 ceramic laser operating at 1000 Hz pulse repetition rate. Using a YAG poltcrystalline rod with Nd3+ concentration at 1 at.% as the gain medium, pumping with 808 nm laser-diode-arrays, the Q-switched laser output at 1064 nm wavelength with 23 mJ pulse energy and less than 12 ns FWHM pulse width are obtained at a pumping power of about 400 W, the slope efficiency is around 15%, the output beam divergence angle is about 1.2 mrad.

中国普通野生稻（Oryza rufipogon Griff.）群体遗传学及保护策略的研究

普通野生稻的基因资源对水稻的育种已经起过并将继续起至关重要的作用。所以，研究和保存其遗传多样性具有重要的意义。首先对普通野生稻在我国的分布现状作了较为全面的野外调查。采集了69个群体，近2000个个体的硅胶干燥叶片。研究了从硅胶干燥的小量叶片中高效率、高质量制备DNA的方法。并用此方法制备了44个代表群体，1168个个体的总DNA，建立了中国普通野生稻的总DNA库。随机选取19个引物对29个群体、651个个体的总DNA进行了RAPD扩增。统计出群体和地区内的多态性片段百分比（PPB），RAPDistance和WINAMOVA程序联用分析遗传变异在地区间、地区内群体间和群体内的组成。广西濠江流域5个野生群体的分析结果表明了中下游群体的PPB值显著高于中上游群体。从而从分子水平上证实了水流对无性繁殖体的传播影响了沿江分布群体的遗传多样性和遗传结构。6个现有原位保护群体的分析结果说明了5个群体值得进一步原位保护，而另一个群体适合异位保护。中国境内29个群体的统计分析揭示出群体间的遗传多样性差异很大（PPB值从23.29%到46.18%）。广东具有的PPB值最高（79.12%），其次是海南（77.11%）和广西（68.67%）。因而，华南是我国普通野生稻的遗传多样性中心。18个群体AMOVA分析结果均表明了遗传变异主要存在于群体内，但群体间业已有较大的遗传分化。从175个随机引物中筛选出9个引物，成功地鉴定出5个群体的克隆多样性和克隆结构。这二者与群体的生态环境，特别是水分状况密切相关。也同时受人类干扰强度的影响。而与群体所处的纬度没有明显的相关性。 根据以上结果，普通野生稻原位保护的策略是选取分布在不同地理区域、遗传多样性水平高的群体。分布在广东、海南和广西的6个群体，具有很高的遗传多样性，建议加以原位保护。此外，孤岛状隔离在我国普通野生稻分布区边缘的3个小群体也应立即进行原位保护。此外，原位保护的群体应给予适度的干扰以维系较高的克隆多样性和遗传多样性。在进行遗传多样性研究和异位保护时，每群体的取样个体数应不少于25株，相邻取样个体间的距离应大于12米。

海南岛蕨类植物的分类、区系地理与保育

摘要 "基于形态－地理学方法，通过野外调查，结合大量标本研究，在前人研究的基础上，对海南蕨类植物的分类进行了进一步修订;主要根据蕨类植物的现代地理分布，结合古生物学等有关资料，初步探讨了海南蕨类植物的区系性质与起源;根据IUCN2001年红色名录的等级和标准，对海南濒危蕨类植物的现状进行了初步评估，讨论了海南蕨类植物的受威胁原因，提出了有关保护的对策。主要结果如下： 1. 海南现有蕨类植物56科140属439个种及种下分类群（包括421种、15变种、2亚种和1变型），其中包括1个中国分布新记录和27个海南分布新记录，1新种――海南符藤蕨Teratophyllum hainanense;另有11个名称首次被处理为异名;澄清了海南假瘤蕨Phymatopteris hainanensis和圆顶假瘤蕨P. obtusa的模式问题，为滇桂三相蕨Ataxipteris dianguiensis、海南假瘤蕨P. hainanensis和浅杯鳞盖蕨Microlepia ampla指定了后选模式。 2. 海南蕨类区系具有以下特点：i. 以水龙骨科Polypodiaceae、金星蕨科Thelypteridaceae、铁角蕨科Aspleniaceae、叉蕨科Tectariaceae和观音座莲科Angiopteridaceae为表征科;ii. 明显的热带性质，科的97.5％、属的92.5％、种的83.6％为热带分布成分;iii. 很高的物种多样性与物种密度，但属内种系贫乏;iv. 与中南半岛的联系最为紧密，海南140个蕨类属中有136个与中南半岛共有，两地属的相似性系数达到87.2%;v. 海南蕨类区系就地起源于华夏古陆，起源时间可以追溯至早石炭世以前。 3. 海南439种蕨类（包括421种、15变种、2亚种和1变型）中，183种为常见蕨类，113种属于资料缺乏的种类（DD），47种属于近危（NT），53种属于易危（VU），37种属于濒危（EN），6种属于极危（CR）。海南的受威胁蕨类植物有96种，海南的绝大部分受威胁蕨类植物都生于保护区以内或得到有效保护的林区之内，已初步得到保护。导致海南96种蕨类受威胁的因素，除了植物本身的生物生态学特性和地理分布上的限制外，主要是人类活动的影响，特别是海南森林在上个世纪被大规模砍伐。为了保护这些受威胁植物，应加强保护区和林区的管理，实施就地保护，积极开展迁地保护和人工繁殖。 "

Intra- and interspecific variation of the CCR5 gene in higher primates

We have evaluated the molecular evolution of the chemokine receptor CCR5 in primates. The chemokine receptor CCR5 serves as a major co-receptor for human immunodeficiency virus/simian immunodeficiency virus (HIV/SIV) infection. Knowledge of evolution of the CCR5 molecule and selection on the CCR5 gene may shed light on its functional role. The comparison of differences between intraspecific polymorphisms and interspecific fixed substitutions provides useful information regarding modes of selection during the course of evolution. There is marked polymorphism in the CCR5 gene sequence within different primate species, whereas sequence divergence between different species is small. By using contingency tests, we compared synonymous (SS) and nonsynonymous (NS) CCR5 mutations occurring within and between a broad range of primates. Our results demonstrate that CCR5 evolution did not follow expectations, of strict neutrality at the level of the whole gene. The proportion of NS to SS at the intraspecific level was significantly higher than that observed at the interspecific level. These results suggest that most CCR5 NS polymorphisms are slightly deleterious. However, at domains more closely correlated with its known biological functions, there was no obvious evidence to support deviation from neutrality.

A paradigm for virus-host coevolution: Sequential counter-adaptations between endogenous and exogenous retroviruses

Endogenous retroviruses ( ERVs) are remnants of ancient retroviral infections of the host germline transmitted vertically from generation to generation. It is hypothesized that some ERVs are used by the host as restriction factors to block the infection o

一种抗人免疫缺陷病毒Ⅰ型p24蛋白的单克隆抗体及其应用

一种抗人免疫缺陷病毒I型(HIV-1)p24蛋白的单克隆抗体及其应用，属生物技术领域。单克隆抗体的免疫原为HIV-1B亚型p24基因工程重组蛋白；是由免疫小鼠的脾细胞与骨髓瘤细胞融合产生的杂交瘤p3JB9、p5F1和p6F4细胞系分泌产生；属于免疫球蛋白IgG1型；与猴免疫缺陷病毒SIVAGM、猴逆转录D型病毒SRV交叉反应；与CCR5 嗜性病毒株HIVAda-M和耐药株HIV74V反应；p5F1和p6F4能与临床分离株HIVKM018反应，而 p3JB9不能与临床分离株HIVKM018反应。单克隆抗体可以与其它单克隆抗体或多克隆抗体组合，或可作放射性同位素、酶、荧光素化合物、化学发光化合物或胶体金属离子的标记，用于制备定性或定量检测各种体液、培养上清或细胞、组织中p24抗原的试剂。具有制备方法简单，效价高；单克隆抗体特异性强，灵敏度高。

目标物体尺寸的大小对小鼠空间深度感知的影响

探索了小鼠在排除透视、遮挡等空间深度的线索下,是否是依靠视觉目标的尺寸大小来感知空间深度.小鼠放置于可以调节高度的高台上,高台位于仅底面有光线照明、四周黑暗的实验箱内.将由格子构成底部面板的尺寸设计为小鼠估计高度距离的唯一线索,设置了3个空间尺度的底板,分别按2/3的比例缩小,并设置7个高度.在同一高度下每测试一轮即对底板的尺寸进行随机变换.记录小鼠跳落前在高台上停留的时间,研究小鼠对高度的判断是否受到底板尺寸的影响.结果表明所有大小线索条件下小鼠在高台上停留的时间随高度的增加而延长.在20～30cm的高度范围,小鼠不以大小为线索的信息来判断深度,可能主要以双眼视差产生的深度信息来判断高度.而在小于20cm和大于30cm的高度范围,特别是在更高的距离上如50cm、60cm和70cm,小鼠以目标大小信息为线索来对深度进行判断,以弥补在这些条件下双眼深度信息的不足.在理论上说这是由于小鼠只有三分之一的(中央)视野为双眼视野区.实验的行为范式可以应用到以转基因鼠为模式生物的实验中,以研究此类行为与基因之间的关系.