基于PXI总线的阵列探测器数据获取系统

描述了一种适用于阵列探测器的数据获取系统。系统基于PXI总线, 采用标准NIM插件作为前端电子学。系统软件采用C/C++语言编写, 在线分析通过调用ROOT类库实现, 系统运行在Linux操作系统下。多次测试结果表明, 系统稳定可靠, 单个ADC通道可以处理的最大事例率为40 kHz。A data acquisition system for array detectors is described. The system is based on PXI bus with standard NIM modules used as front\|end electronics. The system software is written in C/C++ language with its online analysis modules realized by ROOT class library. Several runs of the system under Linux show that it is reliable and is capable of handling event rates up to 40 k events/s for 1 ADC channel.     

Local density of states around two nonmagnetic impurities in cuprate superconductors

The local density of states (LDOS) around two nonmagnetic impurities which are located at different sites is studied within the two-dimensional t-J-U model. The order parameters are determined in a self-consistent way with the Gutzwiller projected mean-field approximation and the Bogoliubov-de Gennes theory. When the two impurities are located one or two sites away, we find the superconductivity coherence peaks are more strongly suppressed and the zero-energy peak (ZEP) has split into two peaks. Whereas when the two impurities are located next to each other, the ZEP vanished, and LDOS does not change a lot compared with the case away from the impurities.     

A novel chemical biology and computational approach to expedite the discovery of new-generation polymyxins against life-threatening Acinetobacter baumannii

Multidrug-resistant Gram-negative bacteria represent a major medical challenge worldwide. New antibiotics are desperately required with ‘old’ polymyxins often being the only available therapeutic option. Here, we systematically investigated the structure–activity relationship (SAR) of polymyxins using a quantitative lipidomics-informed outer membrane (OM) model of Acinetobacter baumannii and a series of chemically synthesized polymyxin analogs. By integrating chemical biology and all-atom molecular dynamics simulations, we deciphered how each residue of the polymyxin molecule modulated its conformational folding and specific interactions with the bacterial OM. Importantly, a novel designed polymyxin analog FADDI-287 with predicted stronger OM penetration showed improved in vitro antibacterial activity. Collectively, our study provides a novel chemical biology and computational strategy to expedite the discovery of new-generation polymyxins against life-threatening Gram-negative ‘superbugs’.

Multidrug-resistant Gram-negative bacteria have been an urgent threat to global public health. Novel antibiotics are desperately needed to combat these ''superbugs''.     

Progress of nanoscience in China

Fast evolving nanoseienees and nanotechnology in China has made it one of the front countries of nanotechnology development. Ill this review, we summarize some most recent progresses in nanoseienee research and nanotechnology development in China. The topics we selected in this article include llano-fabrication, nanocatalysis, bioinspired nanoteehnology, green printing nanotechnology, nanoplasmonics, nanomedicine, nanomaterials and their applications, energy and environmental nanoteehnology, nano EHS （nanosafety）, etc. Most of them have great potentials in applications or application-related key issues in future.     

Degradation and recovery properties of AlGaN/GaN high-electron mobility transistors under direct current reverse step voltage stress

Direct current (DC) reverse step voltage stress is applied on the gate of AlGaN/GaN high-electron mobility transistor (HEMT). Experiments show that parameters degenerate under stress. Large-signal parasitic source/drain resistance (R_S/R_D) and gate-source forward I-V characteristics are recoverable after breakdown of the device under test (DUT). Electrons trapped by both the AlGaN barrier trap and the surface state under stress lead to this phenomenon, and surface state recovery is the major reason for the recovery of device parameters.     

双黄连口服液1H NMR质量稳定性分析方法研究

采用NOESYPR1D（水峰抑制）技术,测定双黄连口服液的¹H NMR谱图,用Mnova和Excel 2003软件分析处理谱图,以相似度为指标,判别分析不同厂家、不同批次的双黄连口服液中主要成分的差异. 所建立的双黄连口服液的¹H NMR质量分析方法可以有效判别不同批次双黄连口服液质量的差异. 实验方法简单、快速、稳定、重现性好,可以为中药成方制剂的质量评价提供新的思路和方法.     

动力UH模型及其有限元应用

饱和砂土在循环载荷下具有复杂的应力应变关系, 通常表现出液化过程中的大变形以及往返活动性现象. 为简单有效地模拟上述特性, 在超固结UH模型的基础上, 将其扩展为可考虑砂土动力加载下的本构模型. 具体做法有3点: (1)改变屈服面椭圆长短轴之比, 将比值定义为反映应力诱导各向异性转轴斜率的函数; (2)引入旋转硬化规则, 用来反映应力诱导各向异性; (3)建立一个与旋转硬化规则以及临界状态特性相协调的统一硬化参数. 模型预测结果表明, 所提动力模型可简单、有效地用于砂土在动力载荷下应力应变关系的模拟. 最后将该动力UH模型嵌入到有限元软件中, 三维地基的动力加载模拟结果表明, 动力UH模型可方便地应用于岩土工程实践中.      

Effect of passive plates on vertical instability in the EAST tokamak

The effect of passive plates on vertical displacement control in the EAST tokamak is investigated by open loop experiments and numerical simulations based on a rigid displacement model.The experiments and simulations indicate that the vertical instability growth rate is reduced by a factor of about 2 in the presence of the passive plates,where the adjacent segments are not connected to each other.The simulations also show that the vertical instability growth rate is reduced by a factor of about 10 if all adjacent segments on each passive plate loop are connected to each other.The operational window is greatly enlarged with the passive plates.     

Finite-time synchronization of switched stochastic R?ssler systems

This paper presents the finite-time synchronization between switched stochastic R?ssler systems accompanied by a time-driven switching law. Based on the Ito formula and Lyapunov stability theory, the finite-time synchronization of switched stochastic master-slave R?ssler systems and the finite-time stability for the mean of error states are developed with the proposed feedback controller. Numerical simulations demonstrate the effectiveness of the proposed methods.