A 3 Tesla Superconducting Magnet for Hall Sensor Calibration

A 3 T superconducting magnet with a 70 mm diameter warm bore and energy storage of 47 kJ has been successfully fabricated and tested, which can be used to calibrate Hall sensors in high magnetic field as well as conduct superconducting experiments. The magnet consists of three solenoid coils and an iron yoke. The homogeneity of the magnetic field in the region of interest (ROI) is +/- 6.0 x 10(-5). The coils of the magnet were fabricated with NbTi-Cu superconducting wire and the stray magnetic field is shielded by an iron yoke. The coils and yoke are fully immersed in a helium vessel. The optimized structural design, stress and quench simulation, fabrication and test results are presented in this paper.

Self-assembly of T-shaped rod-coil block copolymer melts

Self-assembled behavior of T-shaped rod-coil block copolymer melts is studied by applying self-consistent-field lattice techniques in three-dimensional space. Compared with rod-coil diblock copolymers with the anchor point positioned at one end, the copolymers with the anchor point at the middle of the rod exhibit significantly different phase behaviors. When the rod volume fraction is low, the steric hindrance of the lateral coils prevents the rods stacking into strip or micelle as that in rod-coil diblock copolymers. The competition between interfacial energy and entropy results in the formation of lamellar structures and the increasing thickness of the lamellar layer with increasing rod volume fraction.

How does solvent molecular size affect the microscopic structure in polymer solutions?

Monte Carlo simulation has been used to investigate the effects of linear solvent molecular size on polymer chain conformation in solutions. Increasing the solvent molecular size leads to shrinkage of the polymer chains and increase of the critical overlap concentrations. The root-mean-square radius of gyration of polymer chains (R-g) is less sensitive to the variation of polymer concentration in solutions of larger solvent molecules. In addition, the dependency of R-g on polymer concentration under normal solvent conditions and solvent molecular size is in good agreement with scaling laws. When the solvent molecular size approaches the ideal end-to-end distance of the polymer chain, an extra aggregation of polymer chains occurs, and the solvent becomes the so-called medium-sized solvent. When the size of solvent molecules is smaller than the medium size, the polymer chains are swollen or partially swollen. However, when the size of solvent molecules is larger than the medium size, the polymer coils shrink and segregate, enwrapped by the large solvent molecules.

Surface morphology evolution of thin triblock copolymer films during spin coating

The surface morphology evolution of thin poly(styrene-block-ethylene/butylenes-block-styrene) (SEBS) triblock copolymer films as a function of the copolymer concentration was investigated by means of dynamic mode atomic force microscopy. At a relatively low copolymer concentration (0.025% w/v), the periodically orientated stripes were observed. This kind of surface patterning produced in the spin-coating process has not been reported in the literature before. It has been shown by our experiment that a shearing and stretching field can cause flexible polymer coils or aggregates to orientate during the spin coatings At a copolymer concentration of 0.05% w/v, SEBS molecule aggregates form network structures in the whole film. With further increase of the copolymer concentration, a continuous film with a microphase-separated structure was visualized.

Identification and expression of TRAF6 (TNF receptor-associated factor 6) gene in Zhikong Scallop Chlamys farreri

Tumor necrosis factor receptor-associated factor 6 (TRAF6), a key signaling adaptor molecule common to the TNFR superfamily and IL-IR/TLR family, is important not only for a diverse array of physiological processes functions of the TNFR superfamily, but also is involved in adaptive immunity and innate immunity. In this report, the first bivalve TRAF6 (named as CfTRAF6) gene is identified and characterized from Zhikong scallop Chlamys farreri. The full-length cDNA of CfTRAF6 is of 2510 bp, consisting of a 5'-terminal untranslated region (UTR) of 337 bp, a 3'-terminal UTR of 208 bp with a canonical polyadenylation signal sequence AATAAA and a poly (A) tail, and an open reading frame (ORF) encoding a polypeptide of 655 amino acids. The predicted amino acid sequence of CfTRAF6 comprises characteristic motifs of the TRAF proteins, including a Zinc finger of RING-type, two Zinc fingers of TRAF-type, a coiled-coil region, and a MATH (the meprin and TRAF homology) domain. The overall amino acid sequence identity between CfTRAF6 and other TRAF6s is 28-68%. Phylogenetic analyses of CfTRAF6 sequence with TRAF sequences from other organisms indicate that CfTRAF6 is a true TRAF6 orthologue. The mRNA expression of CfTRAF6 in various tissues is measured by Real-time RT-PCR. The mRNA transcripts are constitutively expressed in tissues of haemocyte, muscle, mantle, heart, gonad and gill, but the highest expression is observed in the gonad. The temporal expressions of CfTRAF6 mRNA in the mixed primary cultured haemocytes are recorded after treatment with 20 mu g mL(-1) and 0.5 mu g mL(-1) peptido-glycan (PGN). The expression level of CfTRAF mRNA is down-regulated from 1.5 h to 3 h after the treatment with 0.5 mu g mL(-1) PGN, and then recovers to the original level. While the expression of CfTRAF6 is obviously decreased after treatment with 20 mu g mL(-1) PGN, and reach the lowest point (only about 1/9 times to control) at 3 h. The result Suggests that CfTRAF6 can be greatly regulated by PGN and it may be involved in signal transduction and immune response of scallop. (C) 2008 Published by Elsevier Ltd.

栉孔扇贝(Chlamys farreri)Toll样受体及其信号传递相关基因的克隆与表达

扇贝是我国海水养殖的重要品种，但自1994年以来，养殖扇贝陆续爆发的大规模死亡，不但造成了巨大的经济损失，而且直接威胁到现有产业的生存和发展。引起扇贝大规模死亡原因是多方面的，其主要原因是养殖环境恶化、扇贝种质衰退和抗病力下降。因此，深入研究扇贝免疫防御机制，探讨提高机体抗病力的有效途径和方法，改良种质和培育抗病品系，无疑是解决目前困扰扇贝养殖业健康可持续发展的必经之路。 Toll样受体（TLRs）家族是新近发现的模式识别受体（PRRs），参与识别病原体相关的分子模式（PAMPs），在天然免疫系统中起着非常重要的作用。哺乳动物中Toll样受体信号通路还参与诱导树枝状细胞成熟、参与免疫耐受、参与凋亡发生发展、介导非感染性因素的识别等，被视为联系天然免疫和获得性免疫的桥梁。同时果蝇的Toll信号通路也是不具备获得性免疫的果蝇赖以抵御病毒、细菌和真菌感染，介导天然免疫反应的重要信号通路。 本研究采用大规模EST测序方法，结合Genome Walker库的构建和cDNA末端快速扩增技术，从栉孔扇贝克隆得到CfToll-1、CfMyd88、CfTRAF6和CfCactus这四个Toll样受体信号通路基因的全长cDNA，同时用荧光实时定量PCR技术检测了这些基因的组织分布及在脂多糖（LPS）和肽聚糖（PGN）刺激下的表达规律。 栉孔扇贝Toll样受体（CfToll-1）的cDNA序列全长4308 bp，包含5’非翻译区（UTR）211 bp，3597 bp的开放阅读框，500 bp的3’UTR，最后为18个腺嘌呤的ploy A 尾巴。开放阅读框编码1198个氨基酸的多肽，该多肽的估计分子量为137.41kd，估计的等电点为5.62，该多肽有信号肽，具有一个预测的跨膜区，因此是一种跨膜蛋白。经BLAST比对，CfToll-1基因与节肢动物多种Toll蛋白高度的相似性。SMART（Simple Modular Architecture Research Tool）软件分析，CfToll-1包含典型的Toll样受体的结构：富含亮氨酸的重复序列的胞外区（leucine-rich repeats, LRR），一段跨膜结构域，以及胞内区的TIR结构域（Toll/IL-1 receptor homologous region）。利用Real-time RT-PCR发现CfToll-1mRNA在扇贝体内普遍存在于血细胞、肌肉、外套膜、心、性腺和鳃组织中。利用体外培养的原代血细胞系研究不同浓度LPS刺激后CfToll-1的表达变化，结果显示低剂量（100ng.mL-1 ）LPS 使CfToll-1 mRNA表达量减小，该变化在1.5h、3h 和9h组差异显著，虽然在6h组表达量稍有恢复，但尚未达到对照水平；用1μg.mL-1LPS处理细胞时， 6h组CfToll-1表达量明显上调，约为对照水平的2倍。证实细菌结构脂多糖对CfToll-1基因的表达有影响，且这种影响有剂量依赖效应。 栉孔扇贝Myd88同源基因（CfMyd88）的cDNA序列全长1554bp，包含5’UTR 427 bp，1101bp的开放阅读框，最后为18个腺嘌呤的ploy A 尾。CfMyd88的开放阅读框可编码367个氨基酸的多肽，该多肽的估计分子量为42.37kD，估计的等电点为5.71。利用SMART程序分析发现CfMyd88编码了Death和TIR结构域, 这两个结构域是Myd88特征结构。BLAST程序发现扇贝的序列与数据库哺乳动物的Myd88基因高度同源。原代培养的扇贝血细胞在受到PGN刺激后，CfMyd88 mRNA表达在1.5小时开始下调，直到9小时下调至对照表达量的1/10，证实肽聚糖结构对CfMyd88基因的表达有影响。 栉孔扇贝TRAF6同源基因（CfTRAF6）的cDNA序列全长2510bp，包含5’UTR 337 bp，1965bp的开放阅读框，3’UTR 208bp，最后为21 个腺嘌呤的ploy A 尾巴。CfTRAF6开放阅读框编码655个氨基酸的多肽，该多肽的估计分子量为74.09kD，估计的等电点为6.01。InterPro Scan在线分析发现CfTRAF6有典型的TRAF蛋白家族的特征结构，包括的一个指环结构，两个锌指结构，一个MATH （the meprin and TRAF homology）结构域以及Coiled-coil区域。CfTRAF6的序列与数据库多物种的TRAF6高度同源，同源性最高的是乌贼序列（Identity＝68）和鼠类（Identity＝45%）。利用Real-time RT-PCR，发现CfTRAF6在各组织普遍存在，在性腺中的表达最高。原代培养的扇贝血细胞在受到不同浓度PGN刺激后，与CfMyd88的情况一样，CfTRAF6的表达量变化减少，且这种变化随剂量的增加更加明显。 栉孔扇贝Cactus同源基因（CfCactus）的cDNA序列全长2488bp，包含5’UTR 181 bp，840bp的开放阅读框， 3’UTR 1467bp，最后为19个腺嘌呤的ploy A 尾巴。CfCactus的开放阅读框编码279个氨基酸的多肽，该多肽的估计分子量为31.37 kD；估计的等电点为4.74，与果蝇的Cactus基因的等电点相近（4.5）。利用SMART程序分析发现CfCactus主要编码了ANK结构域（ankyrin repeats）。Cactus基因为哺乳动物NF-κB抑制蛋白IκB的同源分子，BLAST 程序发现扇贝的序列与数据库多物种的Cactus或IκB基因高度同源。同源性最高的是太平洋牡蛎（Identity=35%）和圆尾鲎（Identities = 44%）。对CfTCactus mRNA在扇贝的血细胞、性腺、 肠的组织表达进行分析，并同时与CfTRAF6和CfMyd88的表达量进行了对比，发现CfCactus的表达水平明显高于这两个基因，而且CfTRAF6的基因表达量也高于CfMyd88，表现出级联放大效应。正常情况下，三个基因在性腺的表达量最高，推测这条通路可能和发育等功能密切相关。 通过本研究我们首次在双壳类软体动物找得到与果蝇Toll蛋白家族高度同源的CfToll-1基因，同时发现其他三个在Toll样受体信号传递过程中起重要作用的基因，其中包括在软体动物中获得的第一个Toll样受体的接头分子－CfMyd88基因，该结果直接证明软体动物具有与哺乳动物和节肢动物高度类似Myd88依赖的Toll样受体信号通路。同时通过这些基因组织分布的研究以及细菌结构LPS和PGN对这条通路上基因表达的影响，证明扇贝Toll信号通路可能与在果蝇中一样，参与扇贝的发育和免疫防御等多种功能。

卷绕式海绵材料真空磁控溅射镀膜设备的研制

本文介绍了海绵卷绕真空磁控溅射镀膜设备的结构及其特点,采用独特的传动机构,靶极结构及控制方式实现了海绵连续卷绕真空磁控溅射镀膜。

Electrophoretic migration behavior of DNA fragments in polymer solution

A newly developed polymer coil shrinking theory is described and compared with the existing entangled solution theory to explain electrophoretic migration behaviour of DNA in hydroxypropylmethylcellulose (HPMC) polymer solution in buffer containing 100 mM tris(hydroxymethyl)aminomethane 100 mM boric acid, 2 mm ethylenediaminetetraacetic acid at pH 8.3. The polymer coil shrinking theory gave a better model to explain the results obtained. The polymer coil shrinking concentration, C-s, was found to be 0.305% and the uniform entangled concentration, C+, 0.806%. The existence of three regions (the dilute, semidilute, and concentrated solution) at different polymer concentrations enables a better understanding of the system to guide the selection of the best conditions to separate DNA fragments. For separating large fragments (700/800 bp), dilute solutions (HPMC < 0.3%) should be used to achieve a short migration time (10 min). For small fragments (200/300 bp), concentrated solutions are preferred to obtain constant resolution and uniform separation. The best resolution is 0.6% HPMC due to a combined interaction of the polymer coils and the entangled structure. The possibility of DNA separation in semidilute solution is often neglected and the present results indicate that this region has a promising potential for analytical separation of DNA fragments.