Enhancement of transfection efficiency for HeLa cells via incorporating arsinine moiety into chitosan

Arginine-rich peptides have attracted considerable attention due to their distinct internalization mechanism. It was reported that arginine and guanidino moieties were able to translocate through cell membranes and played a critical role in the process of membrane permeation. In this work, arginine was conjugated to the backbone of chitosan to form a novel chitosan derivative, arginine modified chitosan （Arg-CS）. Arg-CS/DNA complexes were prepared according to the method of coacervation process. The physicochemical properties of Arg-CS and Arg-CS/DNA complexes were characterized and the transfection activity and efficiency mediated by Arg-CS/DNA complexes were investigated taking HeLa cells as target cells. Arg-CS was characterized by FTIR and ^13C NMR. Arg-CS/DNA polyelectrolyte complexes were investigated by agarose gel retardation, dynamic light scattering （DLS） and atomic force microscopy （AFM）. The results revealed that the Arg-CS/DNA complexes started to form at N/P ratio of 2：1, and the size of particles varied from 100 to 180 nm. The cytotoxicity of Arg-CS and their complexes with plasmid DNA were determined by MTT assay for HeLa cells, and the results suggested that Arg-CS/DNA complexes were slightly less toxic than Arg-CS. Moreover, the derivative alone and their complexes showed significantly lower toxicity than PEI and PEI/DNA complexes, respectively. Taking HeLa cells as target cells and using pGL3-control as reporter gene, the luciferase expression mediated by Arg-CS was greatly enhanced to about 100 folds compared with the luciferase expression mediated by chitosan at different pH media. These results suggest that Arg-CS is a promising candidate as a safe and efficient vector for gene delivery and transfection.     

英语语用学与语序之间的关系——如何使用语用学理论解释异常的英语语序

英语的语序不仅受到语法规则的限定,而且很大程度上受到语用学原理的约束。变异的英语语序是无法用语法原理去解释的,唯有用语用学原理才能解释这些异常的英语语序。     

基于PCI9054的PCI接口数据通信系统

本文首先介绍了PCI总线接口芯片PCI9054的性能,并从PCI9054接口设计、寄存器配置等方面阐述了该芯片的应用,着重介绍了PCI9054总线操作及其DMA数据传输方式的控制,文章最后还介绍了如何设计、编写Window环境下的PCI驱动程序。     

浅谈城域传送网核心层建设方案

基于城域传送网核心层所面临的新业务承载需求问题,从业务分析、规划设计、网络演进等几个方面予以讨论,并提出了统一规划、分步实施的建网方案.     

基于嵌入式Windows CE的图像采集与显示系统

阐述了一套基于嵌入式Windows CE的图像采集和显示系统。研究设计基于ARM和FPGA相结合的应用于图像采集和显示人机界面嵌入式平台,并给出系统方案设计和工作流程,给出了DMA驱动程序的详细设计思路,以及应用程序实现的方法。     

嵌入式Linux下FPGA 与ARM处理器DMA 数据采集程序设计

在嵌入式系统的高速数据采集过程中,往往需要使用到FPGA与ARM之间的DMA技术,这其中,FPGA在嵌入式Linux下的DMA驱动程序是难点.介绍了在实际工作的过程中,如何实现FPGA的DMA驱动,完成从FPGA中采集红外热图数据的实时传输.     

面向TD-LTE时代的移动城域传送网建设思路

为适应TD-LTE(Time Division Long Term Evolution)业务的承载需求, 对移动城域传送网现状、 TD-LTE主要技术特点及其承载需求、 面向TD-LTE移动城域传送网的技术选择进行了分析。指出面向TD-LTE移动城域传送网应全程采用PTN(Packet Transport Network)技术组网, 以PTN核心层支持L3-VPN(Layer3-Virtual Private Network)方案作为其具体组网模式, 在核心、 汇聚层引入OTN(Optical Transport Network)技术, 以OTN+PTN方式组建城域传送网。结合当前移动城域传送网现状, 提出面向TD-LTE的移动城域传送网的网络结构。给出了面向未来移动城域传送网接入、 汇聚和核心层的建设思路, 以期指导中国移动城域传送网建设。     

一种非阻塞多VP共享缓冲区的描述符提交机制

针对NIC芯片资源和面积受限的特点,设计了一种资源占用少的多VP共享缓冲区的描述符提交机制DAMQ-PD,设计了地址队列记录每个数据的存储地址,结合每个VP的头尾指针,将各VP分散存储于共享缓冲区的数据链接起来,实现了写、读数据的流水操作.设计了启发式信用管理机制HCM,按需动态给各VP分配信用,自动在PIO和DMA这两种描述符提交方式间切换,避免无信用可分配时可能造成对用户进程的阻塞.分析和模拟结果表明,DAMQ-PD资源占用少、缓冲区利用率高、读写流水、消息发射率高,满足了用户进程提交描述符对低延迟和大容量的性能要求.     

基于VxWorks的CPCI总线双向传输设计和实现

推出了一种总线双向传输通信模型,以VxWorks为系统平台,基于CPCI协议,设计并实现了CPCI总线高效率的双向传输。同时,运用二进制信号量和消息队列机制,保障了VxWorks系统下多任务间的通信、逻辑依赖,协调了公共资源的争夺。在现实产品中的成功应用,证明了该设计在工程上的实用性。     

局域网技术比较及其在时控中的应用

本文分析比较了传统的局域网技术以太网和令牌网的特性和适用范围,说明对于有实时处理要求的信息管理系统,可采用两种技术的分层次的综合互连,以兼顾实时控制和办公管理的不同需求。