无插口塑料排水管件易漏水原因分析

20世纪末,国家建设部、国家经贸委、质量技监局、建材局联合印发的《关于在住宅建设中淘汰落后产品的通知》(建住房[1999]295号)中规定,从2000年6月1日起,淘汰砂模铸造铸铁排水管,推荐使用建筑排水塑料管.由于种种原因,这个文件并没有得到认真执行.直到2004年3月建设部发布《建设部推广应用和限制禁止使用技术》的公告之后,住宅建筑才开始大量使用硬聚氯乙烯(PVC-U)建筑排水管.经多年实践,用户不断反馈一些质量问题,最多的是漏水问题.     

COSMO-SAC法筛选环戊烷/新己烷分离萃取剂及过程模拟

利用COSMO-SAC溶剂化模型,计算了无限稀释条件下,几种常见卤代烷烃、环烷醇对环戊烷和新己烷的分离选择性.结果表明,三氯丙烷的表面屏蔽电荷主要在非极性区域分布,同时具有一定的氢键供体能力,展现出对环戊烷和新己烷较好的理论分离能力.将其COSMO-SAC模型参数带入AspenPlus软件,对三氯丙烷萃取精馏分离环戊烷...     

硅材料外加直流电场诱导的线性电光效应

在直流电场作用下,硅单晶的反演对称性被破坏,从而诱导产生二阶非线性光学效应.主要研究了硅材料在外加直流电场作用下诱导产生的场致线性电光效应.以沿(111)面切割的近本征硅材料为样品,采用平行板电容器结构,通过横向电光调制实验,观测到在不同直流偏压下,电光信号随调制电压而线性增加,且直流偏压越大,电光信号增加的斜率越大....     

第三方软件动态测试模型的研究

基于敏捷方法的测试模型大多都是发生在软件研发过程中,这种测试模型虽然客观上适用于快速迭代的软件测试过程,实际上却还是有一定的局限性,比如代码具有传递性。本文基于敏捷方法测试模型提出了一种新的动态测试模型,这种测试模型不仅节省了大量的时间以及成本,同时还为后续设备投入使用提供了有力的保证。     

一种基于GN算法的动态图划分方法

随着图规模的急剧增长,对动态图进行实时处理的需求日益增加。大多现有的算法针对静态图划分是有效的,直接用其处理动态图会带来较大的通信开销。针对该问题,提出一种基于GN算法的动态图划分方法。首先收集一段时间内加入动态图中的顶点;然后,利用GN算法对这些新加入的顶点进行预划分,产生若干个内部联系紧密的社区;最后,将预划分产生的社区结果插入到已经划分好的当前图中。实验从交叉边数和负载均衡度两方面将该方法与传统流式划分方法进行比较,结果表明,在公开数据集上,该方法的交叉边数降低了13%,负载均衡度减少了42.3%。由此可见,该方法的划分质量明显优于传统的流式划分方法。     

A microfluidic approach for development of hybrid collagen-chitosan extracellular matrix-like membranes for on-chip cell cultures

To advance organ-on-a-chip development and other areas befitting from physiologically-relevant biomembranes,a microfluidic platform is presented for synthesis of biomembranes during gelation and investigation into their role as extracellular matrix supports.In this work,high-throughput studies of collagen,chitosan,and collagen-chitosan hybrid biomembranes were carried out to characterize and compare key properties as a function of the applied hydrodynamic conditions during gelation.Specifically,depending on the biopolymer material used,varying flow conditions during biomembrane gelation caused width,uniformity,and swelling ratio to be differently affected and controllable.Finally,cell viability studies of seeded fibroblasts were conducted,thus showing the potential for biological applications.     

常熟华府世家箱形转换层结构设计

常熟华府世家工程是一栋高层建筑,由于在转换梁的布置中有多次梁抬墙的情况,采用整体性好的箱形转换结构。对箱形转换层及其上下若干楼层的受力进行了计算,根据计算结果对箱形转换层进行结构设计。计算结果表明,采用箱形转换层提高了结构的整体性和抗震性能,结构的变形满足规范要求。对箱形转换结构的设计和施工中要注意的问题进行了探讨。     

基于核心能力的建筑企业专业化与多元化的战略选择

通过对建筑企业核心能力和专业化多元化战略的阐述,以及对专业化多元化的类型界定,建立了基于核心能力的建筑企业专业化多元化成长战略选择矩阵,并在此基础上提出了建筑企业在成长生命周期各阶段应采取的成长战略。     

CFG桩在高速公路滑坡路段软基处理中的应用

结合具体工程实例,对 CFG 复合地基处理高速公路软基的方法进行了研究,对加固机理和设计步骤予以阐述,并对加固效果进行了检测分析,可供类似工程地基处理时参考。     

Sulfated Hyaluronan Binds to Heparanase and Blocks Its Enzymatic and Cellular Actions in Carcinoma Cells

We examined whether sulfated hyaluronan exerts inhibitory effects on enzymatic and biological actions of heparanase, a sole endo-beta-glucuronidase implicated in cancer malignancy and inflammation. Degradation of heparan sulfate by human and mouse heparanase was inhibited by sulfated hyaluronan. In particular, high-sulfated hyaluronan modified with approximately 2.5 sulfate groups per disaccharide unit effectively inhibited the enzymatic activity at a lower concentration than heparin. Human and mouse heparanase bound to immobilized sulfated hyaluronan. Invasion of heparanase-positive colon-26 cells and 4T1 cells under 3D culture conditions was significantly suppressed in the presence of high-sulfated hyaluronan. Heparanase-induced release of CCL2 from colon-26 cells was suppressed in the presence of sulfated hyaluronan via blocking of cell surface binding and subsequent intracellular NF-κB-dependent signaling. The inhibitory effect of sulfated hyaluronan is likely due to competitive binding to the heparanase molecule, which antagonizes the heparanase-substrate interaction. Fragment molecular orbital calculation revealed a strong binding of sulfated hyaluronan tetrasaccharide to the heparanase molecule based on electrostatic interactions, particularly characterized by interactions of (−1)- and (−2)-positioned sulfated sugar residues with basic amino acid residues composing the heparin-binding domain-1 of heparanase. These results propose a relevance for sulfated hyaluronan in the blocking of heparanase-mediated enzymatic and cellular actions.