Tensionless Contact Of A Finite Beam Resting On Reissner Foundation

A more generalized model of a beam resting on a tensionless Reissner foundation is presented. Compared with the Winkler foundation model, the Reissner foundation model is a much improved one. In the Winkler foundation model, there is no shear stress inside the foundation layer and the foundation is assumed to consist of closely spaced, independent springs. The presence of shear stress inside Reissner foundation makes the springs no longer independent and the foundation to deform as a whole. Mathematically, the governing equation of a beam on Reissner foundation is sixth order differential equation compared with fourth order of Winkler one. Because of this order change of the governing equation, new boundary conditions are needed and related discussion is presented. The presence of the shear stress inside the tensionless Reissner foundation together with the unknown feature of contact area/length makes the problem much more difficult than that of Winkler foundation. In the model presented here, the effects of beam dimension, gap distance, loading asymmetry and foundation shear stress on the contact length are all incorporated and studied. As the beam length increases, the results of a finite beam with zero gap distance converge asymptotically to those obtained by the previous model for an infinitely long beam. (C) 2008 Elsevier Ltd. All rights reserved.

Deposition of Au/TiO2 film by pulsed laser

Au nanoparticles, which were photoreduced by a Nd:YAG laser in HAuCl4 solution containing TiO2 colloid and accompanied by the TiO2 particles, were deposited on the substrate surface. The film consisting of Au/TiO2 particles was characterized by the absorption spectra, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The adhesion between the film and substrate was evaluated by using adhesive tape test. It was found that the presence of TiO2 dramatically enhanced the adhesion strength between the film and the substrate, as well as the deposition rate of film. The mechanism for the deposition of Au/TiO2 film was also discussed. (c) 2005 Elsevier B.V. All rights reserved.

Influence of Cr interlayer on the structure and optical properties of Ag films on glass substrate by magnetron sputtering

Optical properties and microstructure of Ag film on glass substrate with Cr intermediate layer were studied by using spectrophotometer and XRD. The spectra results showed that introducing Cr intermediate layer reduced the surface roughness and promoted the reflectivity of Ag film. The XRD analysis showed that the crystalline grains increased and the stress decreased. The adhesion was also improved by using the tape test method. (c) 2006 Published by Elsevier B.V.

In vitro anti-HIV and -HSV activity and safety of sodium rutin sulfate as a microbicide candidate

Sodium rutin sulfate (SRS) is a sulfated rutin modified from the natural flavonol glycoside rutin. Here, we investigated its in vitro anti-HIV and -HSV activities and its cytotoxic profile. Fifty percent inhibitory concentration (IC50) values of SRS against HIV-1 X4 virus IIIB, HIV-1 R5 isolates Ada-M and Ba-L were 2.3 +/- 0.2, 4.5 +/- 2.0 and 8.5 +/- 3.8 mu M with a selectivity index (SI) of 563, 575 and 329, respectively. Its IC50 against primary R5 HIV-1 isolate from Yunnan province in China was 13.1 +/- 5.5 mu M, with a Sl of 197. In contrast, unsulfated rutin had no activity against any of the HIV-1 isolates tested. Further study indicated that SRS blocked viral entry and virus-cell fusion likely through interacting with the HIV- I envelope glycoprotein. SRS also demonstrated some activity against human herpes simplex virus (HSV) with an IC50 of 88.3 +/- 0.1 mu M and a Sl of 30. The 50% cytotoxicity concentration (CC50) of SRS was >3.0 mM, as determined in human genital ME 180, HeLa and primary human foreskin fibroblast cells. Minimum inhibitory concentration of SRS for vaginal lactobacilli was >3.0 mM. These results collectively indicate that SRS represents a novel candidate for anti-HIV-1/HSV microbicide development. (C) 2007 Elsevier B.V. All rights reserved.

Whistles of boto, Inia geoffrensis, and tucuxi, Sotalia fluviatilis

Whistles were recorded and analyzed from free-ranging single or mixed species groups of boto and tucuxi in the Peruvian Amazon, with sonograms presented. Analysis revealed whistles recorded falling into two discrete groups: a low-frequency group with maximum frequency below 5 kHz, and a high-frequency group with maximum frequencies above 8 kHz and usually above 10 kHz. Whistles in the two groups differed significantly in all five measured variables (beginning frequency, end frequency, minimum frequency, maximum frequency, and duration). Comparisons with Published details of whistles by other platanistoid river dolphins and by oceanic dolphins suggest that the low-frequency whistles were produced by boto, the high-frequency whistles by tucuxi. Tape recordings obtained on three occasions when only one species was present tentatively support this conclusion, but it is emphasized that this is based on few data. (C) 2001 Acoustical Society of America.

基于带状弹簧的空间望远镜精密展开技术进展

采用带状弹簧构造的可折叠多杆并联结构对卡塞格林型望远镜的次镜进行支撑，并结合在轨调节，可以实现口径<1m的可展开空间望远镜。描述了基于带状弹簧的可展开空间望远镜的结构特点，介绍了近年来发表的四杆支撑、八杆支撑、三杆支撑和六杆支撑等4种基于带状弹簧的空间望远镜精密展开技术的研究进展。建议针对带状弹簧空间望远镜的精密展开技术，应进一步开展结构动力学建模、结构优化以及误差的光电测量和校正等方面的研究。此外，在模拟微重力环境下展开实验也有助于推动展开动力学和展开精度的研究，而非对称展开结构将是今后该项技术的研究方向之一。认为开展基于带状弹簧的空间望远镜精密展开技术的研究将促进基于微小卫星平台的高分辨率遥感成像和自由空间光通信技术的发展。

树突状细胞体外分化成熟的时程、mi/mRNA 表达谱分析和共生菌影响的研究

树突状细胞（dendritic cells, DC）作为机体天然免疫和获得性免疫反应的桥梁和枢纽，发挥着重要的启动和调控作用。随着体外诱导方法的建立和生物学技术的进步，有关DC 的基础生物学研究得到了快速的发展，在诱导方法、个体发生及基因表达和调控等方面，涌现出很多新的、未解的关键问题。同时，随着对粘膜免疫机理研究的深入，DC 在粘膜生态环境中的功能和影响，渐已成为免疫学研究前沿领域中的热点和要点。在本研究中，为了确定DC 体外分化成熟的最短时程，同时为了研究DC 分化成熟相关的基因表达调控，我们建立了快速的DC 体外诱导方法，分析了体外快速诱导 DC 的mi/mRNA 表达谱。此外，在原始分离的女性生殖道共生乳酸杆菌的基础上，以THP-1作为DC 前体细胞的细胞系模型，开展了女性生殖道共生乳酸杆菌刺激活化 THP-1 的研究，希望能够为乳酸杆菌作为生殖道粘膜免疫疫苗的应用提供理论基础。首先，采用外周血单个核细胞（peripheral blood mononuclear cells, PBMC）来源的CD14+细胞为DC 前体，经过GM-CSF 和IL-4 的刺激，1-6 天后得到未成熟DC （immature dendritic cells, iDC），并经成熟因子（TNF-α, IL-1β, IL-6 与PGE2）诱导 1-2 天后，获得成熟DC（mature dendritic cells, mDC）。经过比较和分析，明确了完全分化和成熟各2 天，即“2+2”，为DC 诱导分化的最佳和最短时程，从而证实和建立了DC 体外快速诱导的体系和方法。该方法获得的iDC 与mDC，具有与传统的“6+2” 方法获得的DC 相同的形态与表型，而且，利用该方法获得的DC 总数高于“1+1”， “1+2”与“6+2”的方法，为DC 的生物学研究提供了基础数据。我们进而采用芯片技术，对体外快速分化成熟的DC 进行了mi/mRNA 表达谱分析，确定了DC 不同分化发育阶段特征性的mi/mRNA 表达差异。结果发现，与CD14+ 单核细胞即DC 前体相比，iDC 与mDC 之间具有更加相近的mi/mRNA 表达方式。 miRNA 表达谱分析则表明，不同的miRNA 表达与DC 的不同分化和发育阶段相关。而且，位于同一基因簇内的miRNA，呈现协同表达的情况。特别值得注意的是，本研究发现了在DC 的某些发育阶段特异表达的miRNA，它们在DC 发育过程中的功能，还未得到诠释，它们在DC 某些分化阶段的特异表达，提示了DC 各分化阶段的相关性与特异性。结合mRNA 表达谱分析，我们发现miRNA 的表达与其目的基因的表达在mRNA 水平呈现负相关的特性。同时，免疫相关mRNA 与miRNA 在DC 体外不同发育阶段的表达亦呈现差异，其中，miRNA（如hsa-miR-181a, hsa-miR-223, hsa-miR-155, hsa-miR-146, hsa-miR-106a 与hsa-miR-20a 等）与mRNA（如ALM1 等）参与了特定的与免疫相关的GO（Gene Ontology）与通路（Pathway），提示这些miRNA 与mRNA 可能通过不同的方式调节控制着DC 的体外诱导过程。在有关粘膜生态环境中DC 的分化、成熟及其功能影响的研究中，我们首先通过各种乳酸杆菌鉴定方法的综合应用，确定了6 种原始分离的女性生殖道主要共生乳酸杆菌：发酵乳酸杆菌（L.Fermentum）、约氏乳酸杆菌（L.Johnsonni）、卷曲乳酸杆菌（L.Crispatus）、革氏乳酸杆菌（L.Gasseri）、詹氏乳酸杆菌（L.Jensenii）与德氏乳酸杆菌（L.Delbrueckii ）。其中，德氏乳酸杆菌（L.Delbrueckii）和发酵乳酸杆菌（L.Fermentum）具有较高的产H2O2 的能力。在此基础上，我们在与THP-1 的共同培养体系中，将乳酸杆菌对DC 前体的作用和影响进行了比较和研究。结果发现，L.Crispatus 在分离的各原始菌株中，具有最强的刺激THP-1 活化的能力，而且，在相同刺激比例下，L.Crispatus 活菌具有比死菌更强的免疫刺激能力，表现为明显上调THP-1 细胞表面标志CD40、CD80、CD86、 CD1a、CCR6 与CD324 的表达水平，同时可诱导活化THP-1 上调表达Th1 型细胞因子。通过FITC-Dextran 吞噬实验，我们发现，经过L.Crispatus 刺激的THP-1 细胞，其吞噬外来抗原的能力明显下降，但尚未检测到经过活化的THP-1 细胞刺激T 细胞增殖的能力。通过流式细胞术分析的方法，我们检测了TLR1、TLR2、TLR4 与TLR6 在不同的刺激分化阶段的表达水平，结果表明，THP-1 主要通过TLR2 与TLR6 识别女性生殖道L.Crispatus。综上所述，本研究首先通过对DC 体外分化成熟的最短时程的分析，确立了快速诱导DC 的最佳方法，进而利用芯片技术，研究了快速诱导DC 的mi/mRNA 表达谱，揭示了DC 体外分化发育过程中可能的调控途径，为进一步研究DC 的基础生物学提供了恰当的模型和具有指向性的线索。同时，通过与DC 前体THP-1 的共同培养体系，证实了生殖道共生乳酸杆菌的免疫调节作用，为以乳酸杆菌为载体的生殖道粘膜免疫疫苗的研究和应用提供了实验依据

beta(+)/EC decay and systematic analysis of Ir-176,Ir-178

The gamma rays following the beta(+)/EC decay of Ir-176,Ir-178 nuclei have been investigated using in-beam gamma-ray experiment. In addition, with the aid of a helium-jet recoil fast tape transport system, the beta(+)/EC decay of Ir-176 was further studied, the new gamma rays were proved and a low-spin isomer was proposed in Ir-176. The isomeric state was analysized according to the systematics in neighboring nuclei.