扣件式钢管脚手架整体承载力性能的ANSYS分析

分析了扣件式脚手架支架倒塌的主要原因,并用ANSYS方法分析了扣件式钢管脚手架的整体承载力性能,为进一步改善扣件式钢管脚手架的整体稳定承载力提供了参考依据.     

扣件式钢管脚手架的施工管理方案

脚手架是建筑施工中的主要施工工具,在现代建筑施工过程中被广泛应用,而扣件式钢管脚手架仍是目前使用最为普遍的脚手架形式.本文分析了扣件式钢管脚手架施工管理中存在的问题,并针对性地提出了施工管理具体方案.     

大跨度大截面梁高大模板支架设计与应用

24 m跨大截面框架梁高支架支撑体系经施工单位采用PKPM施工安全计算软件进行设计,采用扣件式钢管脚手架,经实践,扣件式钢管脚手架支撑体系完全能够满足结构施工的安全性、经济性的要求。     

高层建筑施工中悬挑式脚手架的设计与应用

结合工程实例,介绍了高层建筑施工中悬挑扣件式脚手架的设计与应用技术,并针对脚手架的形式和尺寸、构配件强度验算、连墙件稳定性验算、卸载计算和钢丝绳安全系数的取值及其在卸载中的应用等问题进行了探讨.     

钢管竖井架在高层建筑施工中的应用

随着建筑业改革的不断发展,竖井架在高层建筑中的作用不容忽视。本文简要介绍了用钢管扣件搭设竖井架的经验,提出了钢管扣件竖井架在高层建筑中解决垂直运输问题的施工方法,并通过施工实例证明了钢管竖井架的可靠性与适用性。     

超高超大悬挑梁模板支架结构体系安全性分析

以合肥渡江战役纪念馆超高超大悬挑梁施工为工程背景,采用结构力学与有限单元法,对该工程采用扣件式钢管模板支架结构体系的安全性进行分析,并得到工程监测验证,为今后在类似工程中推广应用提供了理论依据和工程实例.     

钢管辊底式连续热处理炉生产线的改造

某钢管有限公司新改建的钢管燃气辊底式连续热处理炉，采用了多项先进技术，可以完成各种规格钢管正火、退火热处理工艺。     

铜管-管壳式换热器的设计

从铜管-管壳式换热器中铜管与管板连接时的受力情况同钢制管壳式换热器中钢管与管板连接时的受力情况的。区别及钢管-管壳式换热器的特点出发。提出铜管-管壳式换热器的设计方法。     

无缝钢管回退式芯棒二辊连轧特性分析

利用有限元软件MSC.Superform对回退式芯棒钢管连轧过程进行数值模拟,探究回退式芯棒二辊连轧钢管的金属变形、力能参数及运动学特点。结果表明:与全浮动芯棒相比,回退式芯棒轧制时金属横向流动较小,降低了孔型开口处金属过充倾向;钢管平均壁厚偏薄,促进了钢管减壁,但可能会造成壁厚收缩;轧制力有一定的降低。与限动式芯棒相比,芯棒轴向力较大,钢管易发生抱棒。     

钢管涡流探伤可靠性分析

从原理上分析了钢管涡流探伤中采用穿过式自比差动线圈对纵向裂纹类缺陷检出率低的原因,并通过试验进行了验证。阐述了影响钢管涡流探伤可靠性的因素,提出了改善钢管涡流探伤可靠性的几点建议。     

Accumulative Sliding Construction Method for Large-Span Latticed Shells

This note proposes an efficient and cost-effective construction method for longitudinally supported large span latticed shell structures, commonly used for storages of existing stockpiles such as coal, stones, etc. The method divides a latticed shell into several segments, each of them is constructed sequentially. First, one segment-width scaffold is built at the assembling end of the structure. Then one segment of the structure is assembled on the scaffold. Once completed, the segmented structure is slid toward the other end of the structure to allow the scaffold to be available for assembling another segment. By repeating the above procedure, the entire segmented structure will form the resulting lattice shells. In the note, this construction method applied to two long span shell structures is discussed in detail. Structural analyses for each of the two accumulative sliding constructions have been examined before the construction, together with some suggestions for future similar applications using the method. From this note, researchers may transform the mobile construction method to explore other construction methods and practitioners of this technology can apply this method more safely and properly.     

Use of islet cells in cell therapy

The results of our previous work [Hibino et al., Biochim. Biophys. Acta 1174 (1993) 162-170] suggested that a highly repetitive DNA component facilitates bending of the helix axis to be recognized by the nuclear scaffold proteins from rat liver, P123 and P130. In the present experiment, it was shown that binding of these proteins to such a repetitive DNA component from rat liver nuclei (370-bp XmnI fragment) is based on a cooperative mode of interaction, although the binding activity of P130 is much higher than that of P123. The immunoblot analysis with anti-phosphoamino acid antibodies suggested that phosphorylation of serine and threonine residues occurs on P123 and P130, but also of tyrosine residue(s) on P130. The phosphatase assay showed that phosphoryl groups on these proteins may be involved in altering the DNA binding activities of the proteins. Thus, the results in the present study imply that phosphorylation of a nuclear scaffold protein in addition to the degree of bending of the DNA helix axis plays an important role in anchoring chromatin to the nuclear scaffold and in construction of a higher-order chromatin structure.     

碳素焙烧炉砌筑施工工艺

包铝南焙烧炉砌筑工程要求的工期紧、工程质量高,为满足甲方要求,我们在脚手架工程中,采用独立式、可移动的搭设方法,在砌筑过程中加强工程质量控制,特别在火道墙这一特殊砌筑过程和各部位的膨胀缝留设上做了大量工作,取得了较好的效果,同时为今后施工同类型工程积累了宝贵经验。     

Perturbed glial scaffold formation precedes axon tract malformation in Drosophila mutants

The longitudinal glia (LG), progeny of a single glioblast, form a scaffold that presages the formation of longitudinal tracts in the ventral nerve cord (VNC) of the Drosophila embryo. The LG are used as a substrate during the extension of the first axons of the longitudinal tract. I have examined the differentiation of the LG in six mutations in which the longitudinal tracts were absent, displaced, or interrupted to determine whether the axon tract malformations may be attributable to disruptions in the LG scaffold. Embryos mutant for the gene prospero had no longitudinal tracts, and glial differentiation remained arrested at a preaxonogenic state. Two mutants of the Polycomb group also lacked longitudinal tracts; here the glia failed to form an oriented scaffold, but cytological differentiation of the LG was unperturbed. The longitudinal tracts in embryos mutant for slit fused at the VNC midline and scaffold formation was normal, except that it was medially displaced. Longitudinal tracts had intersegmental interruptions in embryos mutant for hindsight and midline. In hindsight, there were intersegmental gaps in the glial scaffold. In midline, the glial scaffold retracted after initial extension. LG morphogenesis during axonogenesis was abnormal in midline. Commitment to glial identity and glial differentiation also occurred before scaffold formation. In all mutants examined, the early distribution of the glycoprotein neuroglian was perturbed. This was indicative of early alterations in VNC pattern present before LG scaffold formation began. Therefore, some changes in scaffold formation may have reflected changes in the placement and differentiation of other cells of the VNC. In all mutants, alterations in scaffold formation preceded longitudinal axon tract formation.     

The Case of a Broken Plank

A construction worker was seriously injured after falling from a roof to a concrete floor. He was working on a plank while placing insulation material when the accident occurred. The plank broke into three pieces. Visual observation of the plank indicated a relatively new plank. Further investigation of the plank revealed a grade of structural plank no. 2. A common practice is for a construction worker to use scaffold grade plank, which has twice the capacity of a structural grade plank. This represents the most probable procedural cause of the plank's failure. The most probable enabling cause (internal cause) of the failure is a local split at the midspan, whereas the most probable triggering cause (external cause) is the impact loads produced by the weight of the worker and the insulation material he carried while walking on the plank. The study also concluded a failure mechanism that was initiated by a longitudinal split at the midspan of the plank. The split weakened the plank and led to a transverse break at the midspan.     

A mammalian scaffold complex that selectively mediates MAP kinase activation

The c-Jun NH2-terminal kinase (JNK) group of mitogen-activated protein (MAP) kinases is activated by the exposure of cells to multiple forms of stress. A putative scaffold protein was identified that interacts with multiple components of the JNK signaling pathway, including the mixed-lineage group of MAP kinase kinase kinases (MLK), the MAP kinase kinase MKK7, and the MAP kinase JNK. This scaffold protein selectively enhanced JNK activation by the MLK signaling pathway. These data establish that a mammalian scaffold protein can mediate activation of a MAP kinase signaling pathway.     

Self-association of herpes simplex virus type 1 ICP35 is via coiled-coil interactions and promotes stable interaction with the major capsid protein

The ordered copolymerization of viral proteins to form the herpes simplex virus (HSV) capsid occurs within the nucleus of the infected cell and is a complex process involving the products of at least six viral genes. In common with capsid assembly in double-stranded DNA bacteriophages, HSV capsid assembly proceeds via the assembly of an outer capsid shell around an interior scaffold. This capsid intermediate matures through loss of the scaffold and packaging of the viral genomic DNA. The interior of the HSV capsid intermediate contains the viral protease and assembly protein which compose the scaffold. Proteolytic processing of these proteins is essential for and accompanies capsid maturation. The assembly protein (ICP35) is the primary component of the scaffold, and previous studies have demonstrated it to be capable of intermolecular association with itself and with the major capsid protein, VP5. We have defined structural elements within ICP35 which are responsible for intermolecular self-association and for interaction with VP5. Yeast (Saccharomyces cerevisiae) two-hybrid assays and far-Western studies with purified recombinant ICP35 mapped a core self-association domain between Ser165 and His219. Site-directed mutations in this domain implicate a putative coiled coil in ICP35 self-association. This coiled-coil motif is highly conserved within the assembly proteins of other alpha herpesviruses. In the two-hybrid assay the core self-association domain was sufficient to mediate stable self-association only in the presence of additional structural elements in either N- or C-terminal flanking regions. These regions also contain conserved sequences which exhibit a high propensity for alpha helicity and may contribute to self-association by forming additional short coiled coils. Our data supports a model in which ICP35 molecules have an extended conformation and associate in parallel orientation through homomeric coiled-coil interactions. In additional two-hybrid experiments we evaluated ICP35 mutants for association with VP5. We discovered that in addition to the C-terminal 25 amino acids of ICP35, previously shown to be required for VP5 binding, an additional upstream region was required. This region is between Ser165 and His234 and contains the core self-association domain. Site-directed mutations and construction of chimeric molecules in which the self-association domain of ICP35 was replaced by the GCN4 leucine zipper indicated that this region contributes to VP5 binding through mediating self-association of ICP35 and not through direct binding interactions. Our results suggest that self-association of ICP35 strongly promotes stable association with VP5 in vivo and are consistent with capsid formation proceeding via formation of stable subassemblies of ICP35 and VP5 which subsequently assemble into capsid intermediates in the nucleus.     

A HYBRID SCAFFOLD OF POLY(LACTIDE-CO-GLYCOLIDE) SPONGE FILLED WITH FIBRIN GEL FOR CARTILAGE TISSUE ENGINEERING

The poly(lactide-co-glyeolide) (PLGA) sponge fabricated by a gelatin porogen leaching method was filled with fibrin gel to obtain a hybrid scaffold for chondrocytes culture in vitro. The fibrin gel evenly distributed in the hybrid scaffold with visible fibrinogen fibers after drying. In vitro culture it was found that in the hybrid scaffold the chondrocytes distributed more evenly and kept a round morphology as that in the normal cartilage. Although the ehondrocytes seeded in the control PLGA sponges showed similar proliferation behavior with that in the hybrid scaffolds, they were remarkably elongated, forming a fibroblast-like morphology. Moreover, a larger amount of glycosaminoglycans was secreted in the hybrid scaffolds than that in the PLGA sponges after in vitro culture of chondrocytes for 4 weeks. The results suggest that the fibrin/PLGA hybrid scaffold 2 be favorably applied for cartilage tissue engineering.     

Optimization of vaccine responses in early life: the role of delivery systems and immunomodulators

Pooled donor fibrin with an ultimate fibrinogen concentration of 60 mg/ml was used to study its effect on wound healing of surgically created ulcers in a rabbit ear. Water soluble polymer (PEG Mw = 20 KD) beads of 100-150 microns were added (12% by volume) to the fibrinogen to obtain a porous and rough structure. Five 6 mm-diameter ulcers to the depth of bare cartilage were created on each rabbit ear. There were two periods of study (4 and 8 days), with 15 ulcers in each time period, 5 of which were treated with a modified fibrin scaffold, 5 with a non-modified fibrin scaffold, and 5 served as control ulcers. The ulcer sites were subjected to routine histological processing and histomorphometrical quantification. Data analysis revealed significant increases in volume fraction of fibroblast and number of blood vessels in the modified fibrin scaffold treated ulcers over control and non-modified fibrin scaffold treated groups.