Quasi-hexagonal molecular packing in collagen fibrils

Collagen molecules in native 66.8 nm (D) periodic fibrils are widely believed to be assembled into discrete, rope-like substructures, or microfibrils. Several types of microfibril have been proposed (2, 4, 5, 7- and 8-stranded) mainly on the basis of information contained in the medium angle X-ray diffraction patterns of native tendon fibres. These patterns show a series of equatorial and near-equatorial Bragg reflections which indicate that the collagen molecules are arranged on a three-dimensional crystalline lattice. The 4-stranded, 5-stranded and 8-stranded microfibrils are D-periodic with approximate diameter 3.8 nm, and these and the 2-stranded model are supposed to be packed on a three-dimensional lattice whose basal unit cell, (approximately) perpendicular to the fibril axis, is tetragonal (or quasi-tetragonal)with side a, a square root 2 or 2a, where a is approximately 3.8 nm. In this paper we describe a re-interpretation of the X-ray data which leads to a new model for the crystalline regions of the fibril, based on quasi-hexagonal molecular packing without microfibrillar sub-structures, and hence having the character of a molecular crystal.     

Electron microscope evidence for an 80 A unit in collagen fibrils.

Connective tissues are composite structures containing collagen, elastin, glycosaminoglycans, minerals, water and other minor components. In all cases the collagen exists predominantly in fibrillar form. The size distribution of the fibrils does, however, vary markedly with both age and the mechanical requirements of the tissue. Little is known about the mechanism of fibril formation in vivo, although some information is now available form in vitro polymerisation studies. We have now collected new and extensive electron microscope data on the size of collagen fibrils from tendon, skin, cornea and other tissues from both fetal and immature animals. The results reported here show that the diameters of the collagen fibrils thus measured lie close to a multiple of 80 A, a result which may be simply and readily interpreted in terms of the collagen microfibril and its mode of packing.     

基于小波变换的ECG信号伪差消除法

文章利用二进小波的分解与重构方法,对人体心电图信号中常见的几种伪差进行消除,实验表明应用小波变换法可以迅速、有效地消除ＥＣＧ信号中由于肌肉震颤、基线漂移和工频干扰等引起的伪差,为正确判断ＥＣＧ信号提供了保障。     

外源基因在球形芽孢杆菌中的转化

为了扩大芽孢杆菌属的受体系统范围，对球形芽孢杆菌进行了质粒消除，并用含有溶葡球菌酶基因的质粒ｐＥ１９４ｃｏｐ６－１转化，结果表明，该酶基因在球形芽孢杆菌中获得了稳定，高效表达。     

微生物发酵转化黄芩苷生成黄芩素的研究

葡萄糖醛酸酶的菌株HQ10,能够以黄芩为底物,通过发酵将黄芩中的黄芩苷转化为黄芩素. 通过对发酵条件进行优化,黄芩苷转化率近于92%. 发酵产物经TLC、HPLC、质谱等方法检测确定为黄芩素.     

反义ACC合成酶基因导入番茄的研究

 采用农杆菌介导法将携带有反义ACC合成酶基因和NPT II的表达载体pKAC导入番茄栽培品种美国大红五星102、美国大红108、美国大红王、大红II号等中.经过卡那霉素筛选后,获得了一批抗性苗,其中有3株PCR检测为阳性.实验证明,不同激素配比对番茄子叶不定芽的诱导有一定影响,适宜的农杆菌侵染时间和浓度是番茄基因转化成功与否的关键,延迟选择有利于番茄基因转化细胞的生长.     

太阳能转化为氢能之探讨

介绍了新能源、太阳能、氢能,以及太阳能光热利用的低温、中温、高温利用.简述了几种常用的太阳能制氢工艺技术.详细阐述了Zn/ZnO氧化还原反应的太阳能光热化学循环制氢原理和两步法循环制氢的工艺流程.该技术为低成本高效率利用太阳能制氢的新途径,可供业内参考.     

化实对称矩阵为对角矩阵的计算机算法

给出了用合同变换化实对称矩阵A为对角矩阵D，及其同时求得P（P^TAP=D）的计算机算法。     

农杆菌介导AtPCS1基因转化苜蓿

利用RT—PCR扩增拟南芥螯合肽合成酶（AtPCS1）基因全序列．进一步构建AtPCS1的植物表达载体pBI121-AtPCS1,转化农杆菌EHA105;然后用转化的农杆菌EHA105以叶盘法侵染苜蓿甘农一号叶片,在50mg／LKan的筛选压下,经过约80-100d的筛选,获得57棵再生苗．随机取其中9棵再生苗进行PCR检测,其中6棵为阳性．初步鉴定表明AtPCS1基因已整合到苜蓿基因组中．     

Insight into the change in carbon structure and thermodynamics during anthracite transformation into graphite

The thermodynamic and kinetic mechanisms of Taixi anthracite during its graphitization process were explored. To understand the variation trends of carbon arrangement order, microcrystal size, and graphitization degree against temperature during the graphitization process, a series of experiments were performed using Raman spectroscopy and X-ray diffraction(XRD). Subsequently, the influencing factors of the dominant reaction at different temperatures were analyzed using thermodynamics and kinetics. The results showed that the graphitization process of Taixi anthracite can be divided into three stages from the perspective of reaction thermodynamics and kinetics. Temperature played a crucial role in the formation and growth of a graphitic structure. Meanwhile, multivariate mechanisms coexisted in the graphitization process. At ultrahigh temperatures, the defects of synthetic graphite could not be completely eliminated and perfect graphite crystals could not be produced. At low temperatures, the reaction is mainly controlled by dynamics, while at high temperatures, thermodynamics dominates the direction of the reaction.     

将药材产业培育成磐安支柱产业的探讨

浙江磐安县是国家级生态示范县，其药材资源丰富，种植历史悠久．发展药材产业是该县农民致富的重要途径．试图在分析磐安药材产业发展条件、发展现状以及存在问题的基础上，就把药材产业发展成为全面带动磐安经济增长的支柱产业提出了建议。     

Connective tissue growth factor induces transformation of renal fibroblasts into myofibroblasts

Connective tissue growth factor (CTGF) is thought to be a specific mediator of TGF-β profibrogenic effect, but the role of CTGF in the transformation of renal fibroblasts to myofibroblasts, which are the most important host cells in the renal chronic fibrosis, is still unknown. Aimed at observing the biological effect of CTGF, we set up a cell line overexpressing CTGF, and analyzed the amount of myofibroblast and the level of extracellular matrix Collagen Ⅲ mRNA in cultured cells. Our results show that CTGF can directly induce myofibroblasts formation, and increase the level of Collagen Ⅲ mRNA. This suggests that CTGF may be a novel pharmacotherapeutical target protein for the interference with renal fibrosis, thus providing useful theoretic possibility for clinical prevention of chronic progression of kidney disease.