Analysis of the vacancy-interstitial model ofDX centers

I describe the vacancy-interstitial model ofDX centers, in which the substitutional donor atoms relax toward interstitial sites when they capture electrons. This appears to be the only known model ofDX centers which can account for the structure observed by Mooneyet al. in DLTS spectra of dilute Al _x Ga_1-x As alloys. By comparing its predictions with the DLTS and Hall data from Al _x Ga_1-x As alloys of low Al content one can establish values for many of the relevant parameters, such as the enthalpies and entropies (degeneracies) associated with sites surrounded by differing numbers of Al atoms. The data also show that the distribution of donor configurations among the four available neighboring interstitial sites does not attain thermal equilibrium among states of differing energies before being released, although transitions (through tunneling) among states of equal energy may be possible. The model is seen to be consistent with those treated theoretically by Chadi and Chang forDX and by Dabrowski and Scheffler for EL2 centers.     

强闪光烟火药过载能力的实验研究

采用大落锤冲击装置模拟研究了强闪光烟火药的过载能力。实验结果表明:强闪光烟火药在装药密度为1.9×103kg.m-3,实验加载应力653 MPa,装药长度为40 mm时承受的过载为8.59×105g(g=10 m.s-2);在加载应力小于653 MPa范围内,强过载产生的热点不能引燃该强闪光药柱。原因可能是(1)强闪光烟火药中氧化剂的热分解温度和可燃物的着火点很高,难以诱发反应;(2)装药质量得到很大改善,热点产生源减少;(3)压药过程使得KC lO4和铝粉的接触面积增大,热点源产生的热量可以通过金属颗粒较迅速向其周围传递,以致热点熄灭。     

Immunological characterisation of barley polypeptides in lager foam

Eight monoclonal antibodies (mAb) recognising barley polypeptides have been identified from a library developed to wheat prolamins. The specificity or the mAb has been determined using enzyme-linked immunosorbent assay (ELISA) and immunoblotting. Six were of broad specificity, recognising D, B, C and γ-hordeins to varying degrees by both techniques. IFRN 0610 preferentially recognised γ-hordeins by ELISA but was highly specific for this hordein group by immunoblotting. Another mAb, IFRN 0624, bound to a M_r ∽ 18000 polypeptide belonging to the CM protein (trypsin/α-amylase inhibitor) family by immunoblotting. This, or a related protein, was detected by 0624 in all hordein fractions using ELISA. These mAb, together with two others described previously and found to recognise the repeat motif of C hordein, were used in ELISA and immunoblot analysis of Octyl-Sepharose fractions of lager foam. Hordein polypeptides were found in all foam fractions, indicating that much foam protein originates from the malt. The CM-like protein was found present in a virtually unmodified form. In contrast, the repeat motif of C hordein was not detected, indicating that it had either been destroyed or masked by other beer constituents. The foam stabilising agent, propylene glycol alginate (PGA), increased the apparent hydrophobicity of hordein fragments suggesting that at least part of the activity of PGA is mediated by interactions with the hordein components of foam.     

镁合金新兴非熔剂净化工艺的研究及应用

镁合金高温熔炼过程中极易发生氧化燃烧,铸件中气体及夹杂等缺陷的出现便不可避免,针对此问题概述了几种传统的净化工艺及实际使用中遇到的一些问题。重点综述了多种新兴的非熔剂净化工艺,包括电磁净化、超声波净化、稀土净化、复合净化工艺及各自的优缺点,介绍了净化工艺的模拟现状,明确了今后研究工作的重点(探索高效、简洁的镁熔体净化工艺),并结合现状对未来我国镁产业的发展进行了展望。     

Accelerated Ionic Motion in Amorphous Memristor Oxides for Nonvolatile Memories and Neuromorphic Computing

Memristive devices based on mixed ionic–electronic resistive switches have an enormous potential to replace today's transistor‐based memories and Von Neumann computing architectures thanks to their ability for nonvolatile information storage and neuromorphic computing. It still remains unclear however how ionic carriers are propagated in amorphous oxide films at high local electric fields. By using memristive model devices based on LaFeO₃ with either amorphous or epitaxial nanostructures, we engineer the structural local bonding units and increase the oxygen‐ionic diffusion coefficient by one order of magnitude for the amorphous oxide, affecting the resistive switching operation. We show that only devices based on amorphous LaFeO₃ films reveal memristive behavior due to their increased oxygen vacancy concentration. We achieved stable resistive switching with switching times down to microseconds and confirm that it is predominantly the oxygen‐ionic diffusion character and not electronic defect state changes that modulate the resistive switching device response. Ultimately, these results show that the local arrangement of structural bonding units in amorphous perovskite films at room temperature can be used to largely tune the oxygen vacancy (defect) kinetics for resistive switches (memristors) that are both theoretically challenging to predict and promising for future memory and neuromorphic computing applications.     

网络信息安全技术综述

阐述了网络信息安全的三个组成方面,具体分析了在实际应用中的网络安全技术手段,探讨了国内外研究开发网络信息安全技术的现状、发展趋势及我们所应着重采取的策略.     

p-nitrobenzonitrile纳米有机薄膜的超高密度信息存储研究

采用扫描隧道显微镜（STM）在p-nitrobenzonitrile(PNBN)单体有机薄膜上进行信息记录点的写入研究。通过在STM针尖和高定向裂解石墨（HOPG）衬底之间施加一系列的电压脉冲进行信息记录点的写入,得到了一个信息点点径小于1nm,对应存储密度高达10^13 bit/cm^2的信息存储点阵,电流－电压（I－V）曲线表明,薄膜上非信息点存储区域是高电阻区,而信息点存储区域是导电区,具有0－1信息存储特性,PNBN单体有机薄膜的存储机制可能是规则排列的PNBN分子在强电场作用下由有序向无序的转变,使得薄膜的电阻由高阻态向低阻态转变,从而实现信息点的写入。     

机载双波长偏振激光雷达探测大气气溶胶分布

为了满足在区域尺度上大气气溶胶垂直分布的探测需求,在中国科学院重大科技基础设施项目“航空遥感系统”的资助下,研制了机载双波长偏振激光雷达。本文介绍了该机载激光雷达的主要功能和性能参数,以及在华北地区开展的飞行观测实验,取得的结果表明,该机载激光雷达性能稳定,其探测精度达到设计要求,可以为污染源的识别和传输路径的探测提供高时空分辨率的数据,为认知大气气溶胶的微物理特性和分类提供了重要的机载遥感平台。     

高补偿硅的光敏感特性

对电阻率为5 ·cm的p型单晶硅,在高温条件下采用扩散金属锰的方法,得到高补偿硅。并在室温(25℃)和液氮温度(196℃)下,测试了这种高补偿硅材料对光强的敏感性。测试结果表明:这种材料是一种光敏感材料,其敏感性受外加的电压、样品的温度及补偿后样品的电阻率影响。