Axial load behavior and strength of tubed steel reinforced-concrete (SRC) stub columns

This paper presents experimental and analytical studies on the behavior of tubed SRC stub columns subjected to axial compressive load. Fourteen circular tubed SRC (CTSRC) and fifteen square tubed SRC (STSRC) stub columns were tested to investigate the failure mode and axial loaded behavior of tubed SRC columns. The effect of diameter/width to thickness ratio of the tubes was studied. The effect of height to diameter/width ratio of the separated tubes in tubed SRC columns was studied to investigate the effect of bond and friction between tube and concrete on the behavior of tubed SRC columns. The test results indicated that tubed SRC stub columns exhibited higher axial load capacity than common SRC columns with the same volumetric steel ratio. Elastic–plastic analysis on the steel tube was employed to study the mechanism of tubed SRC stub columns subjected to axial compression. Equations for the prediction of the axial load strength of tubed SRC stub columns were also proposed based on the proposed experimental results.     

型钢混凝土中高剪力墙正截面受弯的开裂荷载和极限荷载的计算方法

为了研究两种型钢混凝土剪力墙(内置型钢框架的混凝土剪力墙和内置型钢桁架的混凝土剪力墙)在受弯情况下的正截面受力状态,以这两种型钢混凝土中高剪力墙和普通钢筋混凝土中高剪力墙在无轴力作用下的单调和反复水平加载试验为基础,通过力学分析和参考现有规范,主要考虑型钢组件对墙体受弯性能的影响,提出了此两种型钢混凝土中高剪力墙在受弯状态下正截面开裂荷载和极限荷载的计算方法,进一步提出了简化计算方法,并将计算结果与试验结果进行比较验证,为此种构件的工程设计提供算法。     

钢-混凝土组合结构的特点和应用

分析了钢一混凝土组合结构的类型、组成方式及受力特点，并研究了最新的组合结构形式，指出充分利用钢和混凝土两种材料各自优势，进行优化组合，可以造出各种经济效益好、性能优越的结构来。最后探讨了组合结构在工程实践中的应用情况，并分析了组合结构的发展方向。     

Modeling the intact form of the {alpha}1-proteinase inhibitor

The structure of the intact form of the serpin SRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">₁-proteinaseinhibitor has been modeled based on the assumption that thecentral strand s4A of the six-stranded ß-sheet A ofthe cleaved inhibitor is not incorporated into the sheet ofintact SRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">₁-proteinase inhibitor. This strand was removed fromits position in the center of the sheet by suitable rotationsabout the backbone dihedrals of Lys343 using molecular graphics.The resulting structure was then annealed using molecular dynamics(MD) while applying progressive distance restraints to the reactivepeptide bond (Met358-Ser359) for 50 ps. During this time, thedisrupted ß-sheet reformed to create a five-strandedß-sheet with strands 3 and 5 in a parallel arrangement.This change and accompanying structural rearrangements are largelyconfirmed by the X-ray structure of plakalbumin, whose structurereflects the overall structure of intact serpins. The successfulmodeling experiment demonstrates the utility of MD for makinggross structural predictions based on related structures. Thebinding loop of the intact form is modeled to allow dockingwith serine proteinases, in particular thrombin, which mosthighly constrains the possible conformations of the bindingloop.     

型钢混凝土扁梁抗剪承载力的研究分析

主要研究配箍率和型钢腹板高度对型钢混凝土扁梁抗剪承载能力的影响.通过改变扁梁的箍筋间距和型钢腹板高度,采用ANSYS有限元程序计算得到其抗剪承载力,并对计算结果进行了对比分析,从而得出这两个主要影响因素对型钢混凝土扁梁抗剪承载力的影响.     

型钢混凝土异形柱研究现状及分析

异形柱住宅结构,因其具有柱肢厚度与填充墙相等,室内没有柱楞突出,便于装修和家具布置,增加实际使用面积等优点,得到广大用户和开发商的青睐。但是普通钢筋混凝土异形柱具有延性差、承载能力有限、梁柱节点布筋复杂,不利于施工等弱点,使其应用受到了一定的限制。型钢混凝土异形柱继承了型钢混凝土承载能力高、延性好的优点,同时能克服钢筋混凝土异形柱的不足,因此,有望在住宅结构中发挥重要作用,应用前景广阔。本文主要介绍型钢混凝土异形柱的特点及国内外的研究现状,提出型钢混凝土异形柱推广应用亟待解决的问题。     

酥性饼干用小麦粉的溶剂保持力特性研究

选用国内外25种市售小麦粉,研究了小麦粉的溶剂保持力(SRC)特性和酥性饼干品质之间的关系。结果表明,小麦粉的溶剂保持力与酥性饼干的品质具有显著的负相关性,其中小麦粉的水保持力、碳酸钠保持力和蔗糖保持力与酥性饼干品质的相关性较显著。适宜制作高品质酥性饼干的小麦粉应具有较低的溶剂保持力。建议酥性饼干用小麦粉的溶剂保持力指标为:水SRC≤55%,碳酸钠SRC≤70%,乳酸SRC≤90%,蔗糖SRC≤100%。     

A sequence motif in the transmembrane region of growth factor receptors with tyrosine kinase activity mediates dimerization

A mechanism by which ligand binding to the extracellular domainof a growth factor receptor causes activation of its cytoplasmictyrosine kinase domain is that binding promotes receptor dimerization.Recently we proposed a model in which dimerization of the transmembraneSRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">-helices in one member of this family, rat neu, is mediatedby the presence of three specific residues. This paper showsthat a similar sequence motif is observed in 18 of the 20 transmembraneSRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">-helices of the tyrosine kinase family of growth factor receptors.The motif encompasses a five residue segment in which position0 (P0) requires a small side chain (Gly, Ala, Ser, Thr or Pro),P3 an aliphatic side chain (Ala, Val, Leu or Ile) and P4 onlythe smallest side chains (Gly or Ala). In addition other featuresof the transmembrane sequences are reported. It is concludedthat the dimerization of transmembrane SRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">-helices may be a generalmechanism of tyrosine kinase activation in this family of growthfactor receptors.     

Replacing the ({beta}{alpha})-unit 8 of E.coli TIM with its chicken homologue leads to a stable and active hybrid enzyme

In order to investigate how structural modifications interferewith protein stability, we modified a (ßSRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">)-unit inE.coli triosephosphate isomerase (TIM), a typical (ßSRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">)-barrelprotein, assuming that the pseudosymmetrical ß-barrelcan be divided into eight successive loop/ß-strand/loop/SRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">-helixmotifs. We replaced the eighth (ßSRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">)-unit of E.coliTIM with the corresponding chicken (ßSRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">)-unit. The substitution,involving the replacement of 10 of the 23 residues of this (ßSRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">)-unit, was evaluated first by modelling, then experimentally.Modelling by bomology suggests how the amino add replacementsmight be accommodated in the hybrid E.coli/chicken TIM (ETCM8CHI).Both natural and hybrid recombinant TIMs, overproduced in E.coli,were purified to homogeneity and characterized as to their stabilityand kinetics. Our kinetic studies show that the modificationperformed here leads to an active enzyme. The stability studiesindicate that the stability of ETIM8CHI is comparable to thatof the wild type TIM.     

The relative positions of alanine residues in the hydrophobic core control the formation of two-stranded or four-stranded {alpha}-helical coiled-coils

The objective of this study was to investigate the positionaleffect of hydrophobic interactions in the SRC="http://peds.oxfordjournals.org/math/alpha.gif" ALT="{alpha}" BORDER="0">-helical interfacein controlling the formation of two-stranded and four-strandedcoiled-coils. Two disulfide-bridged antiparallel coiled-coilswere designed which differ only in the position of a singleAla residue in the middle heptad: in peptide 2H the Ala residuesare in register (in the same rung), while in peptide 4H theyare not. Data from size-exclusion chromatography and sedimentationequilibrium experiments showed that under benign conditionspeptides 2H and 4H were two-stranded and four-stranded coiled-coilsrespectively. These results, in conjunction with molecular modelingstudies, suggest that when four Ala residues are in the sameplane of a potential four-stranded coiled-coil, the small sidechains of Ala would create a large cavity in the hydrophobicinterface of the potential four-stranded structure which isdestabilizing and favors the two-stranded, disulfide-bridgedcoiled-coil. In contrast, an alternating Leu-Ala hydrophobicpacking in the two planes distributes the potential cavity overa larger region, which may be partially filled by minor adjustmentsof the neighboring Leu side chains. As a result, there is stillsufficient hydrophobic contact to maintain the four-strandedstructure.