Preparation of chloro-functionalized reduced graphene oxide by silver-catalyzed radical reaction

It is well-known that chemical functionalization of graphene has the great significance.We report the development of a new synthesis method of chloro-functionalized reduced graphene oxide(rGOCl).The rGOCl was prepared by radical reaction,and treatment of carboxyl graphene oxide(GOCOOH) with N-chlorosuccinimide(NCS) at 90℃ for 10 h under an atmosphere of nitrogen,using silver nitrate as catalyst.The morphologies and structures of the prepared materials were investigated by field-emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),Raman spectroscopy and the thermal gravimetric.Results indicated that the rGOCl can be readily obtained from graphene oxide(GO) in three steps.     

Gastradefurphenol,a minor 9,9'-neolignan with a new carbon skeleton substituted by two p-hydroxybenzyls from an aqueous extract of “tian ma”

Gastradefurphenol (1), a minor 9,9'-neolignan with a novel carbon skeleton substituted by two p-hydroxybenzyls was isolated from an aqueous extract of the Gastrodia elata rhizomes (tian ma). Its structure was determined by extensive spectroscopic data analysis. Solvent-dependent free rotational restriction of bonds and equilibrium of two molecular states are discussed by comparison of the NMR spectroscopic data of 1 in acetone-d₆ with those in CD₃OD. A biogenetic pathway of 1 is postulated to be associated with metabolic processes of L-tyrosine.     

基于弱相干光源测量设备无关量子密钥分发系统的误码率分析

测量设备无关量子密钥分发系统可以免疫任何针对探测器边信道的攻击, 并进一步结合诱惑态方法规避了准单光子源引入的实际安全性问题. 目前实验中一般采用弱相干光源, 但是该光源含有一定比例的空脉冲和多光子脉冲. 本文针对弱相干光源的具体特性, 采用量子力学的描述, 将各个器件进行量子化处理, 并同时考虑探测器的具体性能参数的影响, 分别给出了通信双方各自发送的脉冲含有特定光子数时产生的成功贝尔态和错误贝尔态的概率公式, 从理论上对相位编码和偏振编码测量设备无关量子密钥分发系统的误码率进行了定量分析, 分别推导并模拟了通信双方采用的平均光子数对称和不对称时误码率随传输距离的变化情况, 结果表明在偏振编码Z基中, 多光子脉冲不会引起误码; 在偏振编码X基和相位编码中, 受多光子影响, 产生的误码率较大. 对于不同的编码方式, 误码率均随传输距离的增加有不同程度的升高, 长距离传输时, 平均光子数越小, 产生的误码率越大; 在偏振编码X基和相位编码的短距离传输中, 相对于对称, 通信双方采用的平均光子数不对称时产生的误码率较大.     

基于稳态电热拉曼技术的碳纳米管纤维导热系数测量及传热研究

利用稳态电热拉曼技术测量了碳纳米管纤维对流换热环境下的导热系数. 该方法基于材料拉曼信号与温度之间的关系, 实时探测一维材料在不同电加热(内热源)下的中心点温度, 利用对流环境下的稳态导热模型推导出材料的导热系数, 实现了一维微纳材料热物性的无损化和非接触式测量. 实验发现: 碳纳米管纤维的导热系数远低于单根碳纳米管的导热系数, 但高于碳纳米管堆积床的导热系数. 这表明碳纳米管体材料的热物性主要取决于内部管束的列阵和管束间的接触热阻.     

Robust finite-time H∞ control for a class of uncertain switched neutral systems

This paper investigates the robust finite-time H_∞ control problem for a class of uncertain switched neutral systems with unknown time-varying disturbance. The uncertainties under consideration are norm bounded. By using the average dwell time approach, a sufficient condition for finite-time boundedness of switched neutral systems is derived. Then, finite-time H_∞ performance analysis for switched neutral systems is developed, and a robust finite-time H_∞ state feedback controller is proposed to guarantee that the closed-loop system is finite-time bounded with H_∞ disturbance attenuation level γ. All the results are given in terms of linear matrix inequalities (LMIs). Finally, two numerical examples are provided to show the effectiveness of the proposed method.     

光学微操纵过程的轴平面显微成像技术

光学俘获技术利用光与物质相互作用产生的光势阱效应来实现对微粒的操控,已经成功应用于生物医学、材料科学等交叉领域.在对微粒进行三维俘获时,传统的宽场光学显微技术只能观测到某一平面内微粒的横向运动,对微粒沿轴向运动的观测受到很大限制.本文将轴平面显微成像技术引入光学微粒操控研究中,利用45?倾斜的反射镜把微粒的轴向运动信息转换到横向平面进行观测,与传统宽场显微成像技术相结合,实现了对二氧化硅小球俘获过程横向和轴向运动的同步观测.该成像方法无需扫描和数据重构,具有实时快速等优点,在新型光束光镊、厚样品三维观测和成像等领域具有潜在的应用价值.     

基于颗粒粒度信息分布特征的动态光散射加权反演

宽分布和双峰分布颗粒的准确反演是动态光散射技术至今未能有效解决的难题,尤其峰值位置比小于2:1且含有大粒径颗粒(350 nm)的双峰分布.造成这一难题的主要原因包括:1)单角度测量数据的粒度信息含量不足;2)常规反演方法对测量数据的噪声抑制以及粒度信息利用缺乏针对性.对测量数据(即光强自相关函数)的研究发现,数据噪声主要分布在长延迟时段,而粒度信息集中分布在衰减延迟时段.基于此,本文提出了采用粒度信息分布为底数、调节参数为指数的权重系数对自相关函数进行加权反演的约束正则化方法.由于采用了与粒度信息分布一致的权重系数,该方法既充分利用了衰减延迟时段的粒度信息,又有效地抑制了长延迟时段的数据噪声.不同噪声水平下,宽分布和双峰分布颗粒体系的反演结果表明,与常规反演方法相比,这一方法可以获得更为准确的宽分布和近双峰分布的反演结果.     

Aryl-to-Vinyl 1,4-Nickel Migration/Reductive Cross-Coupling Reaction for the Stereoselective Synthesis of Multisubstituted Olefins

The aryl-to-vinyl nickel 1,4-migration (1,4-Ni migration) reaction has been reported for the first time. The generated alkenyl Ni species undergo a reductive coupling reaction with unactivated brominated alkanes affording a series of trisubstituted olefins. This tandem reaction exhibits mild conditions, a broad substrate scope, high regioselectivity, and excellent Z/E stereoselectivity. A series of controlled experiments have shown that the critical 1,4-Ni migration process is reversible. In addition, the alkenyl nickel intermediates obtained after migration are highly Z/E stereoselective and do not undergo Z/E isomerization. The obtained trace isomerization products are caused by the instability of the product.     

物理型硬件木马失效机理及检测方法

对两种物理型硬件木马造成芯片退化或失效的机理进行了详细分析. 通过使用ATLAS 二维器件仿真系统并结合SmartSpice电路逻辑仿真器, 模拟了两种物理型硬件木马对反相器逻辑电路输出特性的影响. 使用ATHENA工艺仿真系统模拟了掺杂离子注入工艺过程, 实现了掺杂型硬件木马的金属-氧化物-半导体场效应管(MOSFET)器件; 使用热载流子注入退化模型对ATLAS 仿真器件进行热载流子压力测试, 以模拟热载流子注入型硬件木马注入MOSFET器件并造成器件退化失效的过程, 分别将上述掺杂型硬件木马和热载流子注入型硬件木马的MOSFET器件与另一个正常MOSFET器件组成同样的反相器逻辑电路. 反相器使用Spice 逻辑电路仿真输出DC直流、AC瞬态传输特性以研究物理型硬件木马对电路输出特性的影响. 为了研究MOSFET器件的物理特性本身对硬件木马的影响, 在不同温度不同宽长比(W/L)下同样对反相器进行Spice电路逻辑输出仿真. 本文分析了离子掺杂工艺、热载流子注入压力测试形成的物理型硬件木马随压力强度、温度的变化对逻辑电路输出特性的影响. 通过结果对比分析得出了含有物理型硬件木马的逻辑电路在DC直流输出特性上的扰动比AC瞬态传输特性更明显的结论. 因此, 本文提出了一种针对物理型硬件木马的检测流程. 同时, 该检测流程是一种具有可操作性的检测物理型硬件木马的方法.