Experiments and Models of DNA Nano—Catenary Patterns Manipulated by Liquid Flow

Individual DNA molecules were first stretched by a centrifugal force and adsorbed on a modified mica surface.Then,a liquid flow was guided across the surface along a direction perpendicular to the aligned DNA strands.Some nano-catenary-like patterns of DNA molecules were formed,which were revealed by atomic force microscopy.A physical mechanism called the “s-suspension bridge” model has been presented,by which the features of the catenary-like patterns of DNA molecules can be understood quantitatively quite well.     

空间超光谱成像仪前置光学系统的热光学特性(英文)

分析了空间超光谱成像仪前置光学系统的热光学特性。应用有限元方法建立了模拟前置光学系统的热弹性变形模型,并进行了热弹性分析计算;用Zernike多项式拟合分析结果,求得各镜子反射面在热变形后的面型误差和相对于初始理想位置的偏移;利用光学分析设计软件Code V计算得到光学系统的像面与焦面的偏离量,即离焦量,并用多项式拟合得到其随温度变化的规律。计算结果表明,前置光学系统的像面在温度改变时会偏离焦面,离焦量与温度近似地成线性关系,当温度升高时像面最大偏移量为107.4μm,温度降低时像面最大偏移量为106.9μm。该分析结果可作为指导超光谱成像仪改进热控措施,进行调焦补偿的理论参考。     

声强探头相位误差的电补偿技术

以双传声器技术为基础的声强测量方法对两个传声通道的相位特性非常敏感，本文介绍了对声强探头进行相位匹配以及使用精密相位计进行测量的方法和实例，通过在声强探头后级电路中采用一种称相网络进行相位补偿，在大部分频段上减少了相位误差，可以改善声强测量的精度。文中提供了基本的电路原理图和典型的实验数据。     

信息系统安全风险的属性评估方法

首次将属性理论和属性综合评估模型引入信息系统安全风险的评估领域 ,为信息系统安全风险程度的评估提出了一种新方法 ,对于信息系统安全性的动态管理有着积极的意义 .     

镍原子团簇几何结构的紧束缚方法模拟

A transferable tight－binding potential for nickel together with molecular－dyna mics methods and simulated－annealing techniques have been used to study the str uctures and structural properties of nickel clusters.We have obtained the struct ures and their 关键词：     

Compensating focusing for space hyper spectral imager’s fore optical system

The performance of space hyper spectral imager is severely affected by turbulent orbit temperature. Tur-bulence results in a defocus in the fore optical system of the imager. To address this problem, a focusing system is added. A number of simulation methods are applied on the fore optical system to study the relationship between temperature and focusing. In addition, this process is conducted to obtain a practical reference for focusing while the imager is flying on orbit. The obtained correlation between focusing and temperature is proven effective based on ground imaging and simulation testing.     

Morphology and Wettability of [Bmim][PF6] Ionic Liquid on HOPG Substrate

We investigate the morphology and wettability of [Bmira][PF6] ionic liquid （IL） on a highly oriented pyrolitic graphite （HOPG） substrate using atomic force microscopy. Thin films, nanometer-sized droplets, and ＂drop-onlayer＂ structures of the IL are found on the substrate. Films with a thickness of up to 2nm （about 4 IL layers） show the solid-like behavior. In contrast, a dewetting phenomenon is observed for thicker IL films, indicating that the IL films retain liquid properties. The contact angle of a buck IL droplet on the HOPG is measured to be about 35°. The wettability of the bulk IL droplet on the HOPG is found to be quite different from that of IL films. These results indicate that the IL molecules can be organized into various micro-morphologies when they are confined to a solid substrate and show characteristic behavior at nanometer scales.     

用速率方程分析垂直腔面发射激光器的噪声

采用一种合理的噪声模拟方法，用速率方程对垂直腔面发射激光器的噪声特性进行了数值分析，在单模情况下计算了器件的自发辐射因子、输出功率、注入电流、阈值电流等参数与相对强度噪声、频率噪声以及线宽等特性的关系，计算结果与实验基本相符，对优化垂直腔面发射激光器的结构设计和应用条件有所裨益. 关键词：     

用液流操纵单个DNA分子形成纳米悬链线图形

首先用液流拉伸单分子DNA,使其吸附在修饰过的云母基片上.然后让二次液流沿着垂直于已拉伸的DNA的方向流过云母片,用原子力显微镜(AFM)观测,可见DNA单分子片段在基片上形成了一些纳米尺度的悬链线.提出一种“S悬桥”模型能定量地解释这一现象.该研究工作揭示,在DNA的单分子操作中,经典的弹性力学理论足以描述和控制DNA分子二维图形的形成 关键词： DNA 单分子DNA操纵 原子力显微镜(AFM) 纳米悬链线     

Effects of Substrate Hydrophobicity/Hydrophilicity on Height Measurement of Individual DNA Molecules

Effects of substrate hydrophobicity/hydrophilicity on height measurement of individual ds-DNA molecules are investigated with tapping mode atomic force microscopy （TMAFM） and vibrating mode scanning polarization force microscopy （VSPFM）. The measured heights of ds-DNA on hydrophobic highly oriented pyrolytic graphite （HOPG） are remarkably less than those on hydrophilic bare mica and Ni^2＋ treated mica in both TMAFM and VSPFM. By analysing the results, we propose that the hydrophobicity/hydrophilicity of substrate can greatly influence the height measurement of DNA molecules.