基于NS2的网络仿真可视化系统的设计与实现

在网络模拟领域,NS2一直是应用最广泛的软件,但使用难、缺少远程模拟等缺点也局限了其发展。本文针对这些弱点与不足,提出了基于NS2的远程可视化模拟系统的设计方案并给出了实现方法。系统采用Flex和ActionScript编程语言开发客户端,以组件的形式来开发场景库,以分散式的组件自治模式实现了脚本的自动化生成。然后将脚本传入服务器端,通过远程调用服务器端的NS2子进程执行此脚本,同时整合第三方软件库Gawk和Pnuplot,用以分析模拟结果和实现模拟结果的动画显示和曲线描述,让协议研究人员或学生直观且深入地理解网络中的复杂行为,为用户远程学习计算机网络课程提供了良好的实验平台。     

普适服务模式下网络拥塞控制方法的研究

随着社会科学的发展,传统网络服务模式已经被普适计算的新型模式所代替,并随之出现了各种终端设备并存的网络局面,在网络服务的任务迁移中,不可必免地产生拥塞,其直接影响了网络的传输性能。针对当前传统的Red算法在拥塞问题中的不足等问题,设计了一种新的DARed拥塞控制算法,通过NS2的实验仿真表明,该算法在普适计算环境中表现出极好的性能,能有效地避免拥塞,满足了普适服务的要求。     

基于NS2的局域网路由器队列调度算法仿真分析

通过对一中等规模局域网流量分析,得出其流量组成、大小分布等特征;使用实际采集数据,用NS2模拟器模拟分析路由器在实施区分服务前后不同队列调度算法下的性能表现,发现了一些新的特征,由这些新特征可知在实际设备配置过程中,要充分考虑网络实际流量和应用需求,并非所用配置越复杂越好。     

Generation of single-chain Fvs against detergent-solubilized recombinant antigens with a simple coating procedure

Antigen coating on polystyrene is prevented by detergent. We present here a simple procedure to coat detergent-solubilized antigen for subsequent panning selection of single-chain Fv (scFv), the target antigen of which was the hepatitis C virus (HCV) non-structural protein (NS) 4B, an integral membrane protein.     

The Discovery of Potent Nonstructural Protein 5A (NS5A) Inhibitors with a Unique Resistance Profile—Part 2

In ongoing studies towards novel hepatitis C virus (HCV) therapeutics, inhibitors of nonstructural protein 5A (NS5A) were evaluated. Specifically, starting from previously reported lead compounds, peripheral substitution patterns of a series of biaryl‐linked pyrrolidine NS5A replication complex inhibitors were probed and structure–activity relationships were elucidated. Using molecular modelling and a supercritical fluid chromatographic (SFC) technique, intramolecular H‐bonding and peripheral functional group topology were evaluated as key determinants of activity and membrane permeability. The novel compounds exhibited retained potency as compared with the lead compounds, and also showed promising results against a panel of resistance viruses. Together, the results of the study take us a step closer towards understanding the potency of daclatasvir, a clinical candidate upon which the compounds were based, and to designing improved analogues as second‐generation antiviral agents targeting NS5A.     

乙型脑炎病毒SA14-14-2株NS1和E蛋白的原核表达及其免疫原性

目的原核表达乙型脑炎病毒(JEV)NS1和E蛋白,并初步探讨其免疫原性。方法采用RT-PCR法扩增JEVSA14-14-2株NS1和E蛋白基因片段,分别克隆入原核表达载体pET-30a(+)和pET-32a(+),构建重组表达质粒pET-30NS1和pET-32Et,转化大肠杆菌BL21(DE3),IPTG诱导表达,SDS-PAGE分析目的蛋白的表达形式及表达水平。两种蛋白经亲和层析纯化后,Western blot鉴定其反应原性。通过小鼠主动和被动保护力试验及豚鼠病毒血症试验,检测两种蛋白的免疫原性。结果酶切及测序证明重组表达质粒构建正确;表达的重组NS1和E蛋白的相对分子质量分别约为40000和47000,均以包涵体形式表达;纯化的重组NS1和E蛋白的浓度分别为160.7和380μg/ml,均具有良好的反应原性;小鼠主动和被动保护力试验表明两种蛋白均有保护活性;豚鼠病毒血症试验显示,NS1蛋白免疫豚鼠后能明显抑制病毒血症的产生。结论已成功表达并纯化了JEVSA14-14-2株NS1和E蛋白,两种蛋白均有较好的免疫保护活性。     

基于地理信息系统的路由协议研究

针对车辆自组织网络提出了基于地理信息系统的路由协议GBRP,以此来解决节点高速移动而引起的路径重建问题.由于利用了地理信息系统中提取的道路空间信息,该协议可以规避城市环境下车辆自组织网络中存在的固定的或者暂时的拓扑空洞问题.仿真实验结果表明新的路由协议与DSR相比有较高的分组传输率,较低的路由开销,协议扩展性更好,更适合于城市环境下的车载通信.     

乙型脑炎病毒SA14-14-2株NS3基因的克隆及原核表达

目的克隆并表达乙型脑炎病毒SA14-14-2株NS3编码区的基因片段,为重组蛋白进一步的功能研究奠定基础。方法提取乙脑病毒SA14-14-2株总RNA,用RT-PCR法扩增NS3-1、NS3-2基因片段,克隆入原核表达载体pET15bTAT中,构建重组原核表达质粒,转化大肠杆菌Rosetta2,IPTG诱导表达。表达产物经Ni2+亲和层析柱纯化后,进行Western blot鉴定。结果重组原核表达质粒pET15bTAT-NS3-1和pET15bTAT-NS3-2经酶切证明构建正确。表达的重组蛋白相对分子质量约为27000和20000,主要以包涵体的形式表达。重组蛋白纯化后纯度可达80%以上,并可被小鼠抗乙型脑炎病毒SA14-14-2株血清识别。结论已成功克隆了乙型脑炎病毒SA14-14-2株NS3-1和NS3-2基因,并在大肠杆菌Rosetta2中获得表达。     

Optimization of Thienopyrrole‐Based Finger‐Loop Inhibitors of the Hepatitis C Virus NS5B Polymerase

Infections caused by the hepatitis C virus (HCV) are a significant world health problem for which novel therapies are in urgent demand. The NS5B polymerase of HCV is responsible for the replication of viral RNA and has been a prime target in the search for novel treatment options. We had discovered allosteric finger‐loop inhibitors based on a thieno[3,2‐b]pyrrole scaffold as an alternative to the related indole inhibitors. Optimization of the thienopyrrole series led to several N‐acetamides with submicromolar potency in the cell‐based replicon assay, but they lacked oral bioavailability in rats. By linking the N4‐position to the ortho‐position of the C5‐aryl group, we were able to identify the tetracyclic thienopyrrole 40 , which displayed a favorable pharmacokinetic profile in rats and dogs and is equipotent with recently disclosed finger‐loop inhibitors based on an indole scaffold.