Whole-wafer fabrication process for three-terminal double stacked tunnel junctions

A new fabrication process for three-terminal superconducting devices consisting of two Josephson junctions in a stacked configuration is reported. The process is based on the deposition of the whole Nb/Al_xO_y/Nb-Al/Al_xO_y/Nb multilayer on a Si crystalline wafer without any vacuum breaking. Lift-off techniques, anodization processes and a SiO film deposition have been adopted for patterning and insulating the two tunnel stacked junctions. Devices have been characterized in terms of current-voltage (I-V) curves and Josephson critical current vs. the externally applied magnetic field. They show high quality factors (V _m values up to 65 mV at 4.2 K), and good current uniformity. Received 5 June 2001     

"解剖"激光告警

介绍了激光告警的作用,分析了激光告警器的原理、性能要求和分类,然后分别阐述了典型的光谱识别型、相干识别型和散射探测型激光告警器,并对不同类型的激光告警器进行了比较评价.     

半自动定容定位氢化装置及应用

研制半自动定容试液，半自动定位恒速注入KBK4，整个氢化过程不串空气，可用压力全方位喷射冲洗反应室。该装置定容定位准确，操作简便快速，适用于大批量样品分析。通过对8个GSD标准参考物质的分析，分析结果与参考值基本一致，RSD＜6％。     

Improving the specularity of magnetic mirrors for atoms

An array of anti-parallel current-carrying wires creates an inhomogeneous magnetic field capable of reflecting neutral atoms. We present analytical and numerical analyses of the magnetic field produced by such an array, and describe methods for reducing the resulting rms angular deviation from specular reflection to less than 0.1 mrad. Careful choice of cross-sectional wire profiles is shown to dramatically improve specularity of reflection close to the surface. Additionally, we find that the specularity depends on whether the number of wires in the mirror is even or odd, and that there exists an optimal turning height above the surface that maximizes the specularity of reflection from the mirror. Received 16 November 1998     

一种新的两道工序柔性流水车间排序问题

本文针对F_2(p),h11.1|m_1=1,m_2=μ≥2|C_(max)这一问题给出了几种近似算法,并对每种近似算法进行了最坏情形分析,给出了最坏情形界.     

An Accurate Characterization of CRT Monitor (I) Verifications of Past Studies and Clarifications of Gamma

CRT monitors are widely used to view images on the Internet. The color images on the computer graphic display can be printed out or displayed on other monitors through the Internet, and color matching between the original and the reproduction is very important. The color management systems (CMSs) are useful for the color matching. CMSs utilize device profiles, in which color characteristic information is stored, and these profiles are generated by device characterization. Thus, an accurate characterization of the monitor is essential for better color matching. CRT monitor characteristics can be described by the tone reproduction curves (TRCs) of each channel, and color additive matrix. In this paper, these characteristics were investigated from a physical point of view. Various kinds of flare and the interdependence among the channels were also investigated and verified. The definition of the term “gamma” is clarified, which is very often used to describe the TRC. Various definitions are compared and a new definition of S-γ is proposed.     

“薄膜即是界面，界面即是薄膜”：二维有机半导体晶体的研究进展

自首次于聚乙炔发现导电现象以来,具有共轭结构的有机半导体材料赖其种类丰富多样、 制备工艺简捷低耗、以及优异的机械柔性等特点,在“后硅时代”中有望以先进光电子设备展现 其广阔前景,因而多年来备受学界和产业界的瞩目。如何进一步阐明有机半导体中结构和性能之 间的关系,探索电荷载流子微观动力学行为,构筑高性能、新功能的有机光电子器件,是当下有 机电子学领域的前沿核心问题,也是保证其持续发展的基石。近年来,二维有机半导体晶体材料 在秉持高度有序的分子排列与极低的杂质缺陷浓度等优点的同时,更是以“薄膜即是界面、界面 即是薄膜”为一帜,克服传统体材料在研究与应用中的瓶颈,为揭示材料构性关系及其中基本物 理过程提供了良好的平台,也是实现多样化的新型有机光电子器件的理想材料,有望为微纳电子 领域带来新一轮变革。本文从二维有机半导体晶体的制备工艺、电荷载流子微观动力学行为,再 到新型器件的光电功能应用等方面,综述了最新研究进展,做出总结和展望,并提出目前面临的 挑战及未来研究方向,旨在为进一步深入理论研究,结合有机材料与先进技术,推动有机电子学 的发展提供有益帮助。     

超导量子干涉器件

超导现象是一种宏观量子现象.磁通量子化和约瑟夫森效应是两个最能体现这种宏观量子特性的物理现象.超导量子干涉器件(superconducting quantum interference device,SQUID)是利用这两个特性而形成的超导器件.SQUID器件在磁信号灵敏探测方面具有广泛的应用.本文简要介绍低温超导和高温超导SQUID器件的相关背景和发展现状以及应用领域.     

Influences of flexible defect on the interplay of supercoiling and knotting of circular DNA

Knots are discovered in biophysical systems, such as DNA and proteins. Knotted portions in knotted DNA are significantly bent and their corresponding bending angles are comparable with or larger than the sharp bending angle resulting in flexible defects. The role of flexible defects in the interplay of supercoiling and knotting of circular DNA were predicted by a Monte Carlo simulation. In knotted DNA with a particular knot type, a flexible defect noticeably enhances the supercoiling of the knotted DNA and the decreasing excitation energy makes the knotted portion more compact. A reduction in twist rigidity and unwinding of flexible defects are incorporated into the numerical simulations, so that interplay of supercoiling and knotting of circular DNA is studied under torsional conditions. Increasing unwinding not only results in a wider linking number distribution, but also leads to a drift of the distribution to lower values. A flexible defect has obvious effects on knotting probability. The summation of equilibrium distribution probability for nontrivial knotted DNA with different contour length does not change with excitation energy monotonically and has a maximum at an intermediate value of excitation energy around 5 kBT. In the phase space of knot length and gyration radius of knotted DNA, knot length does not anticorrelate with its gyration radius, which is attributed to the flexible defect in the knotted portion, which leads to the release of bending energy and inhibited the competition between entropy and bending energy.