新型β-二酚卟啉光敏剂合成及其与DNA作用

以β-硝基卟啉为原料,分别与2,3-萘二酚或邻苯二酚直接反应,制备了6个新型β-二酚取代卟啉光敏药物,通过UV,~1H NMR,IR,MS,元素分析等手段对化合物进行了结构表征并初步探讨了反应机理.DNA凝胶电泳实验表明,该类光敏剂对pBR322质粒DNA具有很好的光敏切割作用,作为光敏剂或其前体具有很好的应用前景.     

Simultaneous stacking of cationic and anionic compounds in single run capillary zone electrophoresis by two-end field amplified sample injection

In order to extend the application of field amplified sample injection (FASI) in high throughput analysis, a convenient and simple procedure, namely two-end field amplified sample injection (TE-FASI), was developed for the simultaneous stacking of cationic and anionic compounds in a single run capillary zone electrophoresis (CZE). Following the capillary-filling with a buffer of high conductivity, water plug was loaded into each end of the capillary; and two high-field strength zones were generated at both heads of the column when high voltage was applied. Therefore, under suppressed EOF cations and anions can be selectively FASI stacked at anode and cathode head, respectively. After separation, the stacked anions and cations are detected by a common detector placed in the center of the capillary. Under the optimized conditions, the limits of detection for the model cationic (matrine and oxymatrine) and anionic (5-sulfosalicylic acid) compounds were determined as 0.2, 0.2 and 0.06 ng/mL, respectively. Compared with non-stacking conditions, the sensitivities of these compounds were enhanced 1003-, 1330- and 1380-fold, respectively. The results of reproducibility, linearity and real sample analysis show that the proposed procedure is promising to be applied for the simultaneous quantification detection of trace cationic and anionic analytes.     

Establishment of an immunoaffinity chromatography for simultaneously selective extraction of Sudan I, II, III and IV from food samples

The establishment of an immunoaffinity chromatography (IAC) for simultaneously selective extraction of four illegal colorants Sudan dyes (Sudan I, II, II and IV) from food samples was described. The IAC column was constructed by covalently coupling monoclonal antibody (mAb) against Sudan I to CNBr-activated Sepharose 4B and packed into a common solid phase extraction (SPE) cartridge. It was observed that IAC column was able to separately capture Sudan I, II, III and IV with maximum capacity of 295, 156, 184 and 173ng, respectively. The extraction conditions including loading, washing and eluting solutions were carefully optimized. Under optimal conditions, the extraction recoveries of the IAC column for Sudan I-IV at two different spiked concentrations were within 95.3-106.9%. After 50 times repeated usage, 64% of the maximum capacity was still remained. Six food samples randomly collected from local supermarket without spiking Sudan dyes were extracted with IAC column and detected by high performance liquid chromatography (HPLC). It was found that there was no detectable Sudan II, III and IV in all six food samples, but Sudan I with the content of 2.7-134.5ngg(-1) was detected in three food samples. To further verify the extraction efficiency, other three negative samples were spiked with Sudan I-IV at the concentrations of 20ngg(-1) and 50ngg(-1), which were then extracted with IAC column. The extraction recoveries and relative standard deviation (RSD) were 68.6-96.0% and 4.8-15.2%, respectively, demonstrating the feasibility of the prepared IAC column for Sudan dyes extraction.     

Micelle to trapping solution stacking in micellar electrokinetic chromatography

An analytical strategy micelle to trapping solution stacking (MSS) was developed in acidic buffer in micellar electrokinetic chromatography (MEKC). The stacking mechanism is based on the transport, release, capturing of molecules bound to micelle carriers that are made to collapse into trapping solution (TS) to serve as the medium to contain and stacking the analytes. Tetrandrine and fangchinoline were selected as model mixture using sodium dodecyl sulfate (SDS) micelles as carrier to demonstrate this stacking method. The experiments by MSS-MEKC were carried out and further compared with those by normal MEKC. The results reveal that 113–123-fold improvements in the detection sensitivity was obtained for the analytes, and separation and determination of tetrandrine and fangchinoline in Stephaniae tetrandrae S. Moore and Fengtongan capsules were finished under optimum conditions using the sample matrix containing 8.0 mM SDS and TS containing 50 mM H₃PO₄–55% (v/v) ethanol.     

中国数字电视的统一业务平台

该文简要分析了中国数字电视产业链现状以及近年来一些问题产生的技术原因,提出了改变数字电视现状的＂统一业务平台＂的概念和需求,并且按照提出的需求对统一业务平台实现进行了概要设计。     

基于PWM的LED显示屏像素亮度控制方法

提出了通过综合控制发光二极管(LED)驱动芯片输出信号和全局使能信号的脉冲宽度调制(PWM)波形来控制显示屏像素亮度的方法.在基于二进制位权重PWM的基础上,分别研究了直接输出和全局使能控制LED屏像素亮度时,灰度级数与刷新频率和发光效率的关系.研究结果表明,随着灰度级数的增加,采用全局使能PWM方法控制的LED显示屏刷新频率要远远高于直接输出PWM,但全局使能PWM会带来发光效率降低的问题.采用直接输出和全局使能综合PWM的方法,并根据实际情况合理选择二者比例,可很好的兼顾显示屏刷新频率、灰度等级和发光效率,最大限度提高显示质量,增强显示效果.     

Effect of Contact Mode on the Electrical Transport and Field‐Emission Performance of Individual Boron Nanowires

Vapor–liquid–solid processing of boron nanowires (BNWs) can be carried out either using a bottom‐up or top‐down growth mode, which results in different contact modes between the nanowire and the substrate. The contact mode may strongly affect the electrical transport and field‐emission performance of the individual boron nanowires grown on a Si substrate. The electrical transport and field‐emission characteristics of individual boron nanowires of different contact modes are investigated in situ using a scanning electron microscope. The contact barriers are very distinct for the different contact modes. Moreover, the transition from a “contact‐limited” to a “bulk‐limited” field‐emission (FE) process is demonstrated in nanoemitters for the first time, and the proposed improved metal–insulator–vacuum (MIV) model may better illustrate the nonlinear behavior of the Fowler‐Nordheim (FN) plots in these nanoscale systems. Individual BNWs with different contact modes have a discrepancy in their emission stability and vacuum breakdown characteristics though they have similar aspect ratios, which suggests that their electrical transport and field‐emission performance are closely related to their contact mode. Boron nanowires grown in the base‐up mode have better field‐emission performances and are more beneficial than those grown in the top‐down mode for various device applications.     

LTE协议解决方案及系统实现

介绍了LTE特点及现状.协议测试及重要性根现状给出了LTE协议测试解决方案并通过安立公司的MD8430A基站仿真器和MD8435A终端仿真器外加两台控制PC搭建测试平台,在平台上成功实现了LTE终端从搜索注册网络建立连接信令流程及数据传输物理层仿真.仿真速率上行达到50Mbit/s下行100Mbit/s的高速率传输,给出了各流程源程序,对于LTE移动终端的研发具有重要的作用.     

RICB：基于缓冲区溢出的整数溢出漏洞动态分析

Integer overflow vulnerability will cause buffer overflow. The research on the relationship between them will help us to detect integer overflow vulnerability. We present a dynamic analysis methods RICB (Run-time Integer Checking via Buffer overflow). Our approach includes decompile execute file to assembly language; debug the execute file step into and step out; locate the overflow points and checking buffer overflow caused by integer overflow. We have implemented our approach in three buffer overflow types: format string overflow, stack overflow and heap overflow. Experiments results show that our approach is effective and efficient. We have detected more than 5 known integer overflow vulnerabilities via buffer overflow.     

一种应用于纳米尺度器件陷阱电荷表征的新型改进电荷泵方法

随着器件特征尺寸的缩小,热载流子带来的器件蜕化效应越来越严重。电荷泵方法可用于表征陷阱电荷的分布。但由于局部阈值电压窄峰的影响,传统电荷泵法在测试陷阱电荷分布时存在误差。本文提出了一种改进型电荷泵测试方法,可用于精确提取纳米尺度器件中陷阱电荷的横向分布。 本文采用0.12微米的SONOS器件来验证这一方法的有效性。通过编程控制,使SONOS器件形成大约50纳米的阈值电压窄峰。采用新方法测试得到的陷阱电荷分布与测试得到的阈值电压有较好的一致性。