Interaction between alpha-actinin and negatively charged lipids membrane investigated by surface plasmon resonance and electrochemical methods

alpha-Actinin has been shown to be capable of interacting with some special membrane phospholipids directly, which is important for its function. In this study, hybrid bilayer membranes composed of negatively charged lipids are constructed on the surface plasmon resonance gold substrate and on the gold electrode, respectively, and the interaction between alpha-actinin and negatively charged lipids membrane is investigated by surface plasmon resonance, cyclic voltammetry and electrochemical impedance spectroscopy methods. alpha-Actinin is proved to be able to interact with the negatively charged lipids membrane directly. It can also insert at least partly into the membrane or lead to some defect or lesion in the membrane, which increase the permeability of the membrane. This study would bring some insight on the interaction between the alpha-actinin and the cell membranes in vivo.

Extraction kinetics of cerium(IV) from sulfuric acid medium by the primary amine N1923 using a constant interfacial area cell with laminar flow

BACKGROUND: Thermodynamic studies on Ce(IV) extraction with primary amine N1923 demonstrate that primary amine N1923 is an excellent extractant for separation of Ce(IV) from Re(III). In order to clarify the mechanism of extraction and to optimize the parameters in practical extraction systems used in the rare earth industry, the extraction kinetics was investigated using a constant interfacial area cell with laminar flow in the present work.RESULTS: The data indicate that the rate constant (k(ao).) becomes constant when stirring speed exceeds 250 rpm. The apparent forward extraction rate is calculated to be 10(-1.70). The activation energy (E.) was calculated to be 20.5 kJ/mol from the slope of log kao against 1000/T. The minimum bulk concentration of the extractant necessary to saturate the interface (C-min) is lower than 10(-5) mol L-1.CONCLUSION: Studies of interfacial tension and the effects of stirring rate and specific interfacial area on the extraction rate show that the extraction rate is kinetically controlled, and a mass transfer model has been proposed. The rate equation has been obtained as: -d[Ce(IV)]/dt = 10(-1.70)[Ce(IV)] [(RNH3)(2)SO4](1.376). The rate-controlling step has been evaluated from analysis of the experimental results.

Synthesis and characterization of polyethylene/clay-silica nanocomposites: A montmorillonite/silica-hybrid-supported catalyst and in situ polymerization

A novel approach to the preparation of polyethylene (PE) nanocomposites, with montmorillonite/silica hybrid (MT-Si) supported catalyst, was developed. MT-Si was prepared by depositing silica nanoparticles between galleries of the MT. A common zirconocene catalyst [bis(cyclopentadienyl)zirconium dichloride/methylaluminoxane] was fixed on the MT-Si surface by a simple method. After ethylene polymerization, two classes of nanofillers (clay layers and silica nanoparticles) were dispersed concurrently in the PE matrix and PE/clay-silica nanocomposites were obtained. Exfoliation of the clay layers and dispersion of the silica nanoparticles were examined with transmission electron microscopy. Physical properties of the nanocomposites were characterized by tensile tests, dynamic mechanical analysis, and DSC. The nanocomposites with a low nanofiller loading (<10 wt %) exhibited good mechanical properties. The nanocomposite powder produced with the supported catalyst had a granular morphology and a high bulk density, typical of a heterogeneous catalyst system.

A temperature-dependent interaction of neutral red with calf thymus DNA

Neutral red (NR) is used as a probe to study the temperature and concentration dependent interaction of a cationic dye with nucleic acid. A temperature-dependent interaction of NR with calf thymus DNA (CT DNA) has been studied by differential pulse voltammetry (DPV), UV-Visible absorption, circular dichroism (CD) and fluorescence spectroscopy. The experimental results of increasing peak current, changes in the UV-Visible absorption and fluorescence spectra of NR and decreasing the induced circular dichroism (ICD) intensity show that (i) the binding mode of NR molecules is changed from intercalating into DNA base pairs to aggregating along the DNA double helix and (ii) the orientation of NR chromophore in DNA double helix is also changed with the temperature.

Carbon-13 nuclear magnetic resonance spectrum simulation of pyridines and quinolines

Artificial neural network (ANN) and multiple linear regression (MLR) were used for the simulation of C-13 NMR chemical shifts of 118 central carbon atoms in 18 pyridines and quinolines. The electronic and geometric features were calculated to describe the environments of the central carbon atom. The results provided by ANN method were better than that achieved by MLR.

吡啶和喹啉类化合物的碳-13核磁共振波谱模拟

运用多元回归分析和人工神经网法对１８个吡啶和喹啉类化合物的１１８个化学位移进行计算机模拟，并应用碳原子的空间和电子结构特征来表征其所处的化学环境，从而获得了比较好的相关模型。波谱模拟技术对辅助有机化合物结构解析和化学位移的确认是十分有用的工具。

K-2[MoO3(C2O4)].H2O

In the title compound, catena-poly[dipotassium [[(oxalato-O,O')dioxomolybdate]-mu-oxo]monohydrate], oxalate acts as a bidentate ligand coordinating to each Mo atom through the two deprotonated carboxylate groups. The coordination polyhedron of molybdenum is distorted octahedral and there are infinite chains in the structure. Principal dimensions are: Mo-O(terminal) 1.560 (3) and 1.739 (3) Angstrom, Mo-O(bridging) 2.046 (4) and 2.410 (4) Angstrom, and Mo-O(carboxylate) 1.949 (3) and 2.113 (3) Angstrom.

Synthesis and x-ray structure of a highly symmetrical selenium-centered hexanuclear neodymium complex, [(Cp6Nd6Se13)-Nd-t](-) (Cp-t=eta(5)-(BuC5H4)-C-t)

The half-sandwich tert-buthylcyclopentadienyl neodymium complex [(CpNdCl2)-Nd-t(THF)(2)](2) (1) reacts with Na2Se5 to give organoneodymium polyselenide complex [Na(THF)(6)][(Cp6Nd6)-Nd-t(mu(6)-Se)(mu(2)-Se-2)(6)] (2) which has been characterized by X-ray crystallography.

Liquid crystalline polymer as a processing agent in blends of poly(ether-ketone)/LCP70

Blends of a liquid crystalline thermotropic copolyester (LCP70) and an amorphous phenolphthalein based poly(ether-ketone)(PEK-C) with two viscosities were prepared by melt blending. The blends' morphology, rheological and mechanical properties were investigated by DSC, SEM, mechanical and rheological tests. It was observed that the optimum composition of the PEK-C/LCP70 blend was 10 wt% LCP for both mechanical and rheological properties. When the LCP content was less than 10%, the LCP phase existed as finely dispersed fibrous domains with a diameter of about 1 mu m in the matrix, and both tensile and flexural properties were improved. In contrast, when the LCP content reached 20% or more, the LCP domains coalesced to ellipsoidal particles with a diameter of about 5 mu m, and the mechanical properties decreased as a result. It is demonstrated that pure PEK-C with a high viscosity which was difficult to process by melt extrusion, could be extruded conveniently when 10% LCP70 was incorporated. It is emphasized that LCP not only can be used as a reinforcing phase but also an effective processing agent for engineering thermoplastics, especially for those with high viscosity and narrow processing window. (C) 1997 Elsevier Science Ltd.

迟缓爱德华氏菌基因组fosmid文库的构建、opp基因簇的克隆及aroA基因缺失突变株的构建

本研究构建了迟缓爱德华氏菌(Edwardsiella tarda)LSE40 基因组fosmid文库，该文库共包含2 500个克隆，插入片段平均大小为33.6kb，文库总容量约84Mb，覆盖E.tarda LSE40基因组（按5Mb计算）超过16倍。随机挑取1 000个fosmid克隆进行双末端测序共得到1 741条高质量的序列，序列平均长度546 bp，全长949 997bp，约为E.tarda基因组的19％。将这些序列提交到KEGG自动注释服务器KAAS对所得序列进行代谢途径分析，得到E.tarda LSE40的KO (KEGG Orthology) 注释。分析结果表明，与代谢途径相关的基因有932条序列，与环境信息处理相关基因283条，与遗传信息处理相关基因220条，与细胞进程和人类疾病相关的基因分别为64条和16条。同时将序列进行BlastX，按照微生物致病性共同主题找到61个毒力相关基因。Fosmid文库的建立和部分基因组序列的生物信息学分析为进一步研究E.tarda LSE40的致病机制、代谢机制和生理生态机制提供了丰富的物质基础。 通过比较基因组的方法，从E.tarda LSE40 fosmid文库克隆到编码寡肽透过酶的opp基因簇，该基因簇全长6 741bp，含有5个ORF，依次编码OppA-B-C-D-F 5个蛋白；位于oppA和oppB的间隔区和oppF之后的非编码区各有一个茎环结构，推测分别为oppA和opp基因簇的转录终止子。以细菌OppA的保守结构域SBP_bac_5构建系统发生树，结果显示E.tarda LSE40与同属细菌E.ictaluri的亲缘关系最近，与肠杆菌科细菌的亲缘关系较近，与革兰氏阳性细菌的亲缘关系较远，表明OppA的SBP_bac_5结构域可作为细菌分类鉴定的依据。 从E.tarda LSE40 fosmid文库克隆aroA基因全序列，该序列全长1 287bp，编码428个氨基酸，与鲶鱼爱德华氏菌(E. ictaluri)氨基酸相似性在94%，与其他肠杆菌科菌如Escherichia coli和Yersinia enterocolitica相似性在73%-74%。通过In-frame deletion构建了E.tarda LSE40 aroA缺失突变株。与野生型相比，aroA突变株的半数致死量LD50提高了62倍。在牙鲆接种~106cfu/ml的E.tarda细菌时，接种野生型细菌的牙鲆在6天内全部死亡，濒死鱼的细菌数达7.97×108cfu/ 100mg；而接种aroA突变株的牙鲆没有出现死亡，28天后检测不到细菌的存在。实验结果为进一步评价aroA突变株作为减毒活疫苗打下了基础。

Chromosomal mapping of major ribosomal rRNA genes in the hard clam (Mercenaria mercenaria) using fluorescence in situ hybridization

Karyotype and chromosomal location of the major ribosomal RNA genes were studied in the hard clam (Mercenaria mercenaria Linnaeus) using fluorescence in situ hybridization (FISH). Metaphase chromosomes were obtained from early embryos. Internal transcribed spacers (ITS) between major RNA genes were amplified and used as FISH probes. The probes were labeled with digoxigenin-11-dUTP by polymerase chain reaction and detected with fluorescein-labeled anti-digoxigenin antibodies. FISH with the ITS probes produced two to four signals per nucleus or metaphase. M. mercenaria had a haploid number of 19 chromosomes with a karyotype of seven metacentric, four metacentric or submetacentric, seven submetacentric, and one submetacentric or subtelocentric chromosomes (7M + 4M/SM + 7SM + 1SM/ST). Two ITS loci were observed: one located near the centromere on the long arm of Chromosome 10 and the other at the telomere of the short arm of Chromosome 12. FISH signals on Chromosome 10 are strong and consistent, while signals on Chromosome 12 are variable. This study provides the first karyotype and chromosomal assignment of the major RNA genes in M. mercenaria. Similar studies in a wide range of species are needed to understand the role of chromosomal changes in bivalve evolution.

AUV水下回收研究

世界各国对海底的开发探索促进了AUV 技术的发展，但是传统回收AUV 的方法效率低、可靠性差、作业环境危险因此回收一直是影响AUV 广泛应用的主要因素。以至于学者们指出，回收问题是影响AUV 事业发展的瓶颈问题。水下回收被认为是比较有前途的一种回收方法。使用水下回收的方法操作者可以不必冒险下小艇，并且水下回收所使用的设备完全可以利用现有的技术储备。水下回收不仅可以帮助AUV 实现安全回收，而且还具有其他潜在用途。如它可以为AUV 在水下补充能量和交换数据，以及为载入潜器问人员、物资流动提供安全路径。通过分析探索者号AUV 水下回4欠的得失，作者提出种新的水下回收方案。就是当AUV 上浮到一定深度以后自动定深悬浮，派捕捉者(一艘有缆潜器)去捕捉吕标AUV ，然后把AUV 拖人回收舱，有缆潜器的运动可以是受人遥控的也可以是自动的，视具体情况而定。文章中历数了方案实施过程中将遇到的技术难点，并指出捕捉过程中捕捉者和AUV 的运动控制问题是水下回收过程中的关键问题。提出捕捉过程中用模糊逻辑算法来确定捕捉者的捕捉航线，并对控制算法进行仿真。在不同的方案中对AUV的运动控制要求有所不同，文章针对不同的运动控制分别作了讨论，并对其中些运动控制进行了仿真试验。在文章第一章里叙述了AUV 发展的背景和现状，指出AUV 的回收问题是影响AUV (泛应用的瓶颈问题，并总结了探索者号AUV 水下回收得失。在第二章里提出了个水下回收方案，并对这个方案进行了论证。在第三章里提出了水下回收过程中可供选择的三个捕捉方案，并总结了每个方案的优缺点。在第四章里提出用模糊逻辑的方法解决捕捉过程中的运动控制问题e在第五章里建立了AUV 的数学模型，以便于在下一章分析AUV 的运动控制。在第六章里分析了不同捕捉方案中对ACV 控制品质的不同要求，并根据要求讨论了AUV 的运动控制在最后一章里作者对文章作了综述和总结、并对水下回收技术未来的发展趋势作出展望。

新型托辊切管机控制系统设计

文章介绍了一种新型托辊切管机控制系统的设计,对该系统的硬件组态及控制功能作了主要描述。该机床是托辊自动化加工装配线上的一台机电一体化自动加工设备,其主要功能是对托辊装配所需原料管进行定尺切断,并在整个加工过程中自动上下料。整个机床控制系统主要由SIEMENS Simotion D运动控制系统、触摸屏TP177B、远程输入输出模块ET200M等组成。