Numerical simulation of hypersonic viscous flow around space shuttle with method of diffusion analogy

Hypersonic viscous flow around a space shuttle with M(infinity) = 7, Re = 148000 and angle of attack alpha = 5-degrees is simulated numerically with the special Jacobian matrix splitting technique and simplified diffusion analogy method. With the simplified diffusion analogy method the efficiency of computation and resolution of the shock can be improved.

Construction of shuttle, expression vector of human tumor necrosis factor alpha (hTNF-alpha) gene and its expression in a cyanobacterium, Anabaena sp. PCC 7120

The construction of the shuttle, expression vector of human tumor necrosis factor alpha (hTNF-alpha) gene and its expression in a cyanobacterium Anabaena sp. PCC 7120 was reported. The 700-bp hTNF cDNA fragments have been recovered from plasmid pRL-rhTNF, then inserted downstream of the promoter PpsbA in the plasmid pRL439. The resultant intermediary plasmid pRL-TC has further been combined with the shuttle vector pDC-8 to get the shuttle, expression vector pDC-TNF. The expression of the rhTNF gene in Escherichia coil has been analyzed by SDS-PAGE and thin-layer scanning, and the results show that the expressed TNF protein with these two vectors is 16.9 percent (pRL-TC) and 15.0 percent (pDC-TNF) of the total proteins in the cells, respectively, while the expression level of TNF gene in plasmid pRL-rhTNF is only 11.8 percent. Combined with the participation of the conjugal and helper plasmids, pDC-TNF has been introduced into Anabaena sg PCC 7120 by triparental conjugative transfer, and the stable transgenic strains have been obtained. The existence of the introduced plasmid pDC-TNF in recombinant cyanobacterial cells has been demonstrated by the results of the agarose electrophoresis with the extracted plasmid samples and Southern blotting with alpha-(32)p labeled hTNF cDNA probes, while the expression of the hTNF gene in Anabaena sp. PCC 7120 has been confirmed by the results of Western blotting with extracted protein samples and human TNF-alpha monoclonal antibodies. The cytotoxicity assays using the mouse cancer cell line L929 proved the cytotoxicity of the TNF in the crude extracts from the transgenic cyanobacterium Anabaena sp. PCC 7120.

Telomerase Activity and Microgravity-Dependent Apoptosis in Human Leukemia HL-60 Cells

Mammalian cells subjected to conditions of spaceflight and the microgravity environment ofspace; manifest a number of alterations in structure and function. Among the most notable changes incells flown on the Space Shuttle are reduced growth activation and decline in growth rate in the totalpopulation. Other changes include chromosomal aberrations, inhibited locomotion, alteredcytokine production, changes in PKC distribution, and increased apoptos.

基于生态系统服务理论的草地可持续利用评价

草地退化不仅仅是今天中国才发生的事情。历史上曾经发生“黑尘暴”的美国North Dakota州，现在仍然有62.7％土地被用作耕作，林地所占面积仅仅占1％。私有制和种植业较畜牧业的高的利润率，是该州种植业比重高于畜牧业的重要原因。草原保护项目（CRP）得到了美国政府财政的大力支持， 在North Dakota州采用了以草地恢复为主的措施。美国发达的教育体系带来的高流动率，使得North Dakota州自30年代后居住人口稳定在60－70万成为可能，从而避免了我国出现的草原地区不断增加的人口压力。由此可见：草地作为重要的自然资源，不可能完全保护起来;没有其他配套措施，私有制可能会带来新一轮垦殖;草地畜牧业仍然是畜牧业的重要组成部分，畜牧业发展需要结合种植业尤其需要与饲料生产相结合。 依据生态系统服务的理念，首次发展了生态系统服务指数（ESI），试图通过对生态系统服务功能的综合考虑，提出科学的适宜放牧率的评价方法。本文利用美国北达科他州立大学中部草原研究站17年长期放牧试验数据，选取植物多样性Shannon-Wiener指数、地上净初级生产力、土壤表层含水量和单位面积家畜增重等四个指标，通过对不同指标分别赋予不同的权重，计算不同管理目标下ESI及其稳定性，并对单目标管理与多目标管理进行了比较研究。结果表明，对于北美混合普列里(Prairie)草地，围封不利用或建立自然保护区，虽然生态系统比较稳定，但既不能有效的提高植物多样性、初级生产力和土壤水分含量等生态功能，又没有畜产品产出;而在重牧或极重牧处理下虽然获得了较大的畜产品生产，但导致了草地生态系统的退化和较大的系统不稳定性。因此，这两种管理方式在实践中都是不可取的。应用生态系统服务指数综合考虑，认为应该权衡各项生态功能和生产功能，此时轻牧或中牧是最适宜的。因此，ESI的建立避免了单项指标的评价偏差，使得适宜放牧率的确定更加合理。 利用前面构建的多目标权重评价体系，结合内蒙古草原生态系统定位站放牧试验样地的数据，探讨了锡林郭勒盟定位站附近的适宜放牧率为2.67羊/ha，低于单目标条件下的每公顷绵羊4羊/ha。同时在经济学和生态系统系统服务理论的基础上，依据谢高地等人（2001年）的研究，并提出了环境税和生态补偿的标准，分别是每公顷15元和90元。

福尔马林灭活柱状黄杆菌对草鱼免疫相关基因表达的影响

在本研究中,将福尔马林灭活的柱状黄杆菌菌苗(FKG4)经腹腔注射免疫草鱼,以注射灭菌PBS作对照,分别在免疫后1、7、15和28d,提取受免鱼和对照鱼肝脏、脾脏和头肾3种组织中的总RNA并反转录成cDNA,利用Real-time PCR方法对不同组织中C-反应蛋白(CRP)、主要组织相容性复合体I(MHCⅠ)、肿瘤坏死因子(TNFα)、白介素1(IL-1β)、白介素8(IL-8)、Ⅰ型干扰素(IFNⅠ)等6种免疫相关基因的表达进行定量分析。结果发现CRP在受免鱼肝脏中的表达于免疫后1、7d显著高于对照鱼,

柱状黄杆菌胞外多糖对草鱼的免疫促进作用

将柱状黄杆菌胞外多糖(EPS)溶液经腹腔注射免疫草鱼,以注射灭菌生理盐水作对照。免疫一周后,分别提取受免鱼与对照鱼肝脏、脾脏、体肾和头肾4种组织中的总RNA,并通过RT-PCR半定量的方法检测不同组织中C-反应蛋白(CRP)、白介素1(IL-1)、主要组织相容性复合体I(MHC I)、免疫球蛋白M(IgM)、干扰素(IFN)等5种免疫基因的表达情况。结果显示,CRP在受免鱼肝脏中的表达显著上升;MHC I在受免鱼脾脏、体肾中的表达显著下降;IgM在受免鱼4种组织中的表达皆显著上升;IL-1在受免鱼4种组织

中国蔷薇属芹叶组（Rosa Sect. Pimpinellifoliae DC. ex Ser.）的分类学研究

本研究通过我国CDBI、 KUN、PE、SZ等主要标本馆约3, 500份馆藏标本的研究和野外考察相结合，对我国蔷薇属（Rosa L.）芹叶组(Sect. pimpinellifoliae DC. ex Ser.）植物以及相关组的一些种进行了性状特征、形态和微形态的研究，对该组的一些种的形态特征描述进行了补充，同时给出详细的地理和海拔范围分布图。综合花粉以及种子（瘦果）形态的研究结果重新制订了分种检索表，同时，对该组一些形态相近容易混淆的种进行了对比研究，特别对一直存在争议的绢毛复合体（绢毛蔷薇R. sericea Lindl.和峨眉蔷薇R. omeiensis Rolfe）进行了大量宏观形态特征的研究，并用光学显微镜（LM）和扫描电镜(SEM)对二者的花粉及种子形态、微形态进行对比研究和分析，主要研究内容包括： 1. 芹叶组孢粉研究 对芹叶组的10个种及相关的4个组共17个种（18个样品）的植物花粉进行了光镜和扫描电镜观察和比较研究。研究结果表明：蔷薇属植物花粉粒大小为中等偏小，极轴长23.98[21.82(R. graciliflora Rehd. et Wils.)～29.18(R. tsinglingensis Pax. et Hoffm.)] μm，赤道轴长28.65[24.15（R. graciliflora）～34.70(R. davidii Crép.)] μm；花粉属辐射对称等极单花粉，花粉形态赤道面观呈球形到超长球形；极面观为三裂圆形或近圆形,三孔沟，孔缘加厚,具中部突起的桥状盖。花粉外壁纹饰为条纹状，光镜下形态特征相差不大；在电镜下外壁条纹和脊沟内穿孔的形状、大小和频度等特征，常具组至种水平上的可见变异，可作为组至种水平划分的依据。 根据花粉外壁条纹特征及穿孔形状和数目等特征，本研究将这些植物的花粉归为5个类型，并编制了分组检索表。同时，根据条纹状的清晰度，排列方式、条纹形状、穿孔大小及其频度等方面的差异，各有特点，对该组的10个种编制了分种检索表。 2. 芹叶组种子形态研究 应用光学显微镜和扫描电镜对我国蔷薇属芹叶组14个种及相关组5个组共36种植物的种子宏观形态及种皮微形态特征进行了观察研究。结果显示，蔷薇属种子形态多样,形状分别为肾形、卵形或锥形等；种子颜色以淡棕色、褐色以及土黄色为主；种子大小种间相差悬殊，相对体积为（长×宽×厚）36.66（4.79～114.47) mm3。光镜下，种子宏观形态特征具组内一致性，在扫描电镜下种子表面结构特征因种而异，其纹饰以网纹为主，可分为3种类型，即近平滑型、负网纹型和网纹型。研究结果表明，蔷薇属种子表面纹饰与地理分布关系不大,具有组及种内稳定性。其种子形态、大小、表而纹饰类型等特征可作为蔷薇属组及种水平上的分类依据。 结合蔷薇属花粉形态研究结果，得出蔷薇属种皮微形态特征与花粉外壁纹饰特征相吻合，在代表组及种的特征上具相关性的结论。同时根据种子形态、微形态结构特征的组间区别和种间差异编制了分组及芹叶组14个种的分种检索表。 3. 绢毛蔷薇复合体的研究 通过对大量标本的研究、野外观察以及扫描电镜对绢毛蔷薇复合体的花粉形态和种皮表面结构进行研究，通过对小叶、花粉及种子的形态定量分析结果支持Rowley (1959)的观点，将峨眉蔷薇处理为绢毛蔷薇的一个变种。 综上研究结果得出，蔷薇属植物的小叶片数目、花被基数以及花粉及种子形态等性状是较为稳定的，这些特征可很好的作为分类学依据。 The morphology, pollen exine sculpture and seed coat structure of the species of Rosa sect. Pimpinellifoliae and related sections were studied.About 3,500 herbarium specimens at CDBI, KUN, PE, and SZ were examined. Field work in Sichuan and Yunnan were conducted. Revisions of some species were carried out and a new key to species of sect. Pimpinellifoliae was proposed based on morphology, pollen exine sculpture and seed coat structure, Detailed morphological descriptions, geographical distributions and the altitudinal ranges of some taxa are given. The systematics of the species complex, the Rosa sericea complex (R. sericea Lindl. & R. omeiensis Rolfe), was emphasized. This thesis focused on the following three aspects: 1. Pollen morphology of Rosa sect. Pimpinellifoliae The pollen morphology of 18 samples representing 10 species of the Eurasian Rosa sect. Pimpinellifoliae and 7 additional species of related sections was investigated under LM and SEM. The pollen grains are monadic, actinomorphic, equipolar, medium-sized, spheroidal to perprolate in equatorial view, 3-lobed circular or semi-circular in polar view, crassimarginate, pontoperculate, and with striate exine sculpture. The striate sculpture varies among sections and species. The equatorial axis ranges from 17.97 μm (R. sikangensis) to 29.18 μm (R. tsinglingensis) with an average of 23.98 μm in length, while polar axis varies from 24.15 μm (R. gracilifolra) to 34.70 μm (R. davidii) with an average of 28.65 μm in length. The pollens can be divided into five types based on striate sculpture and a key to the sections sampled was proposed accordingly. The pollen morphology of species of sect. Pimpinellifoliae is more homogeneous and different from other sections sampled and did not support the two-series subdivisions in sect. Pimpinellifoliae. A key is also provided based on characers of pollen morphology among species in sect. Pimpinellifoliae. 2. Seed coat structure of Rosa sect. Pimpinellifoliae The seed coat structure of 39 samples representing 14 species of Rosa sect. Pimpinellifoliae and 12 additional species of related sections was investigated under LE and SEM. The seed relative volume (Length × width × thickness) ranges from 4.79 to 114.47 mm3 with an average of 36.66. mm3. The seeds are reniform, ovate or oblong in shape, with orange-brown, light brown or deep brown color. Seed coat sculpture was reticulate or striate-like reticulate. There was no difference in sculpture character of various speices under LM, while three types of seed coat sculpture were identified under SEM and a key to species based on the seed coat sculpture was provided. The three types of seed coat sculpture were nearly smooth, areolate and reticulate. The study of the seed coat sculpture of same species sampled from different populations showed that characters on the seed coat are stable, and thus the size, shape and seed coat sculpture can be used in species level identification. Interestingly, characters in the seed coat sculpture and the pollen morphology in sect. Pimpinellifoliae are consistent at in specific or sectional levels. A key to the 14 species sampled was given based on seed coat sculpture. 3. The study on Rosa sericea complex The Rosa sericea complex contains R. omeiensis and R. sericea. They are morphologically similar to one another and the systematic status of R. omeiensis has been controversial. In this study we examined large numbers of herbarium specimens of R. omeiensis and R. sericea and conducted field observations in the Hengduan Mts.. We also performed SEM study of pollen morphology and seed coat structure of R. omeiensis and R. sericea. We further carried out intensive morphometric study on the leaflet, pollen, and seed morphology. Our results showed that R. omeiensis should be sunk to be a variety of R. sericea, just as Rowley’s treatment in 1959. In conclusion, the features in the number of leaflet and petal, and the morphological character on pollen and seed are relatively stable. Therefore these characters are very useful in taxon delimition.

Regulation of autoinducer 2 production and luxS expression in a pathogenic Edwardsiella tarda strain

Edwardsiella tarda is a bacterial pathogen that can infect both humans and animals. TX1, an Ed. tarda strain isolated from diseased fish, was found to produce autoinducer 2 (Al-2)-like activity that was growth phase dependent and modulated by growth conditions. The gene coding for the Al-2 synthase was cloned from TX1 and designated luxS(Et). LuxS(Et) was able to complement the Al-2 mutant phenotype of Escherichia coli strain DH5 alpha. Expression Of luxS(Et) correlated with Al-2 activity and was increased by glucose and decreased by elevated temperature. The effect of glucose was shown to be mediated through the cAMP-CRP complex, which repressed luxS(Et) expression. Overexpression of luxS(Et) enhanced Al-2 activity in TX1, whereas disruption of luxS(Et) expression by antisense RNA interference (i) reduced the level of Al-2 activity, (ii) impaired bacterial growth under various conditions, (iii) weakened the expression of genes associated with the type III secretion system and biofilm formation, and (iv) attenuated bacterial virulence. Addition of exogenous Al-2 was able to complement the deficiencies in the expression of TTSS genes and biofilm production but failed to rescue the growth defects. Our results (i) demonstrated that the Al-2 activity in TX1 is controlled at least in part at the level of luxS(Et) expression, which in turn is regulated by growth conditions, and that the temporal expression of luxS(Et) is essential for optimal bacterial infection and survival; and (ii) suggested the existence in Ed. tarda of a LuxS/Al-2-mediated signal transduction pathway that regulates the production of virulence-associated elements.

Regulation of autoinducer 2 production and luxS expression in a pathogenic Edwardsiella tarda strain

Edwardsiella tarda is a bacterial pathogen that can infect both humans and animals. TX1, an Ed. tarda strain isolated from diseased fish, was found to produce autoinducer 2 (Al-2)-like activity that was growth phase dependent and modulated by growth conditions. The gene coding for the Al-2 synthase was cloned from TX1 and designated luxS(Et). LuxS(Et) was able to complement the Al-2 mutant phenotype of Escherichia coli strain DH5 alpha. Expression Of luxS(Et) correlated with Al-2 activity and was increased by glucose and decreased by elevated temperature. The effect of glucose was shown to be mediated through the cAMP-CRP complex, which repressed luxS(Et) expression. Overexpression of luxS(Et) enhanced Al-2 activity in TX1, whereas disruption of luxS(Et) expression by antisense RNA interference (i) reduced the level of Al-2 activity, (ii) impaired bacterial growth under various conditions, (iii) weakened the expression of genes associated with the type III secretion system and biofilm formation, and (iv) attenuated bacterial virulence. Addition of exogenous Al-2 was able to complement the deficiencies in the expression of TTSS genes and biofilm production but failed to rescue the growth defects. Our results (i) demonstrated that the Al-2 activity in TX1 is controlled at least in part at the level of luxS(Et) expression, which in turn is regulated by growth conditions, and that the temporal expression of luxS(Et) is essential for optimal bacterial infection and survival; and (ii) suggested the existence in Ed. tarda of a LuxS/Al-2-mediated signal transduction pathway that regulates the production of virulence-associated elements.

迟缓爱德华氏菌(Edwardsiella tarda) LuxS/AI-2群体感应系统研究

从患病牙鲆中分离出迟缓爱德华氏菌株TX1，经报告菌株检测发现TX1有AI-2活性。用梯度PCR和Genome walking的方法克隆了TX1 luxS基因，将luxS基因在大肠杆菌DH5α中表达，证明其具有功能活性。在TX1中，luxS的表达与AI-2的活性基本是一致的，二者均受生长时期和生长条件的调节，即在glucose存在的条件下luxS表达和AI-2活性升高，而在高温条件下luxS表达和AI-2活性降低。glucose对AI-2活性以及luxS表达的影响经过荧光定量PCR，启动子活性检测，AI-2活性检测以及凝胶滞缓等一系列的实验证实是由cAMP-CRP复合物介导的，该复合物可以通过与luxS启动子相互作用而抑制luxS的表达。RNA干扰表明，TX1中luxS表达被干扰以后，对细菌产生了多方面的影响，包括：(1) 降低AI-2水平；(2) 降低细菌的生长能力；(3) 降低Ⅲ型分泌系统相关基因的表达水平以及生物膜的形成能力；(4) 减弱细菌毒力。外源AI-2的添加可以回复Ⅲ型分泌系统相关基因的表达水平以及生物膜的形成，但是并不能修复生长状况，表明LuxS在TX1中具有双重功能，即参与细胞代谢以及群体感应信号传导。基于LuxS/AI-2群体感应系统对细菌毒力的重要性，设计并筛选了一个该系统的阻遏因子5411。Pull-down实验证明5411可以和LuxS特异性结合。研究表明5411在TX1中表达导致细菌毒力显著下降。将5411克隆至牙鲆共生菌FP3中，发现5411可以被分泌到胞外并能被TX1吸收。将表达5411的共生菌导入牙鲆，发现其能够有效阻遏TX1对牙鲆的侵染。 这些结果表明：(1) TX1中AI-2的活性受控于LuxS，而后者则受生长时期和生长条件的调控；(2) luxS的正常表达对于细菌的正常生长和侵染是必需的；(3) LuxS/AI-2群体感应系统调控Ⅲ型分泌系统相关毒力因子的表达；(4) 通过阻遏LuxS/AI-2群体感应系统来抑制病原菌侵染是一种具有潜力的新型病害防控方法。

质子交换膜燃料电池在无缆水下机器人上的应用研究

质子交换膜燃料电池(PEMFC)作为一种新兴的能源,在汽车和航天器上已经获得成功的应用,本文针对水下环境和PEMFC的特点,对PEMFC在无缆水下机器人(UUV)上试验应用的关键技术进行讨论.

一种柔性冲压自动化生产线系统的研制

本文介绍了一种用于大型汽车覆盖件冲压生产的柔性自动化生产线，系统由６台压机、１２台上下料机械手、１台翻转传输装置、４台穿梭传输装置及１台磁力分层装置构成．给出了生产线的主要性能指标、机械手结构简图及单元控制系统框图，简要介绍了系统的工作原理。

叠前时间偏移: 基于波动方程的架构、发展和应用

This dissertation starts from the point that the prestack time migration can been considered as an approximation of the prestack depth migration, giving a wave equation based prestack time migration approach. The new approach includes: analytically getting the travel time and amplitude based on the one way wave equation and the stationary-phase theory, using ‘spread’ imaging method and imaging following the prestack depth migration, updating the velocity model with respect to the flats of the events in CRP gathers. Based on this approach, we present a scheme that can image land seismic data without field static correction. We may determine the correct near surface velocities and stack velocities by picking up the residual correction of the events in the CRP gathers. We may get the rational migration section based on the updated velocities and correct the migration section from a floating datum plane to a universal datum plane. We may adaptively determine the migration aperture according to the dips of the imaging structures. This not only speed up the processing, but may suppress the migration noise produce by the extra aperture. We adopt the deconvolution imaging condition of wave equation migration. It may partially compensate the geometric divergence. In this scheme, we use the table-driven technique which may enhance the computational efficiency. If the subsurface is much more complicated, it may be impossible to distinguish the DTS curve. To solve this problem, we proposed a technique to determine the appropriate range of the DTS curve. We synthesize DTS panel in this range using different velocities and depths, and stack the amplitude around the zero time. Determine the correct velocity and location of the considered grid point by comparing the values.

共反射面元叠加

The seismic survey is the most effective prospecting geophysical method during exploration and development of oil/gas. The structure and the lithology of the geological body become increasingly complex now. So it must assure that the seismic section own upper resolution if we need accurately describe the targets. High signal/noise ratio is the precondition of high-resolution. As one important seismic data processing method, Stacking is an effective means to suppress the records noise. Broadening area of surface stacked is more important to enhance genuine reflection signals and suppressing unwanted energy in the form of coherent and random ambient noise. Common reflection surface stack is a macro-model independent seismic imaging method. Based on the similarity of CRP trace gathers in one coherent zone, CRS stack effectively improves S/N ratio by using more CMP trace gathers to stack. It is regarded as one important method of seismic data processing. Performing CRS stack depends on three attributes. However, the equation of CRS is invalid under condition of great offset. In this thesis, one method based on velocity model in depth domain is put forward. Ray tracing is used to determine the traveltime of CRP in one common reflection surface by the least squares method to regress the equation of CRS. Then we stack in the coherent seismic data set according to the traveltime, and get the zero offset section. In the end of flowchart of implementing CRS stack, one method using the dip angle to enhance the ratio of S/N is used. Application of the method on synthetic examples and field seismic records, the results of this method show an excellent performance of the algorithm both in accuracy and efficiency.