Fast and precise algorithm based on maximum radial symmetry for single molecule localization

We present an algorithm to estimate the location of single fluorescent molecule with both high speed and high precision. This algorithm is based on finding the subpixel position with maximum radial symmetry in a pixelated single molecule fluorescence image. Compared with conventional algorithms, this algorithm does not rely on point-spread-function or noise model. Through numerical simulation and experimental analysis, we found that this algorithm exhibits localization precision very close to the maximum likelihood estimator (MLE), while executes ～1000 times faster than the MLE and ～6 times faster than the fluoroBancroft algorithm.     

Properties of train traffic flow in a moving block system

The development direction of railways is toward the improvement of capacity and service quality, where the service quality includes safety, schedule, high speed, and comfort. In light of the existing cellular automaton models, in this paper, we develop a model to analyze the mixed running processes of trains with maximal speeds of 500 km/h and 350 km/h respectively in the moving block system. In the proposed model, we establish some sound rules to control the running processes of a train, where the rules include the departure rules in the intermediate stations, the overtaking rules, and the conditions of speed limitation for a train stopping at a station or passing through a station. With the consideration of the mixed ratio and the distance between two adjacent stations, the properties of the train traffic flow (including capacity and average speed) are simulated. The numerical results show that the interactions among different trains will affect the capacity, and a proper increase of the spatial distance between two adjacent stations can enhance the capacity and the average speed under the moving block.     

基于多元线性阵列探测器的快速光声层析成像

报道了一种基于相控聚焦的多元线性阵列探测器进行快速光声层析成像的方法和装置,并实现了模拟组织的光声层析成像。实验中采用波长为532nm脉宽为7ns的倍频Q-YAG激光器作为激发光源。多元线性阵列探测器由320个振元组成,采用相控聚焦的方法成像,每次由11个振群的探测器接受信号并合并1路,一幅图像由64路这样的信号组成。实验结果能够正确反映样品中的光学吸收分布。与现有的方法比较,本系统具有快速方便的特点,它有望成为一种组织功能在体成像的新方法,发展成为一种低成本的实用的临床诊断装置。     

Experimental verification of enhanced transmission through two-dimensionally corrugated metallic films without holes

We present experimental results to verify extraordinary optical transmission through two-dimensionally periodic, corrugated metallic films without holes as predicted by Bonod et al. [Opt. Express 11, 482 (2003)]. We also experimentally confirmed that using symmetric structures (metallic films sandwiched between two identical dielectric media) is advantageous for boosting the coupling of surface plasmons so as to create strong transmission peaks.     

冲击作用下的摩擦力效应实验研究

针对摩擦力效应产生的机理, 本文设计了三种不同尺寸的试件进行SHPB实验, 得到了摩擦力效应对实验的定量影响, 在此基础上对混凝土的DIF进行了修正研究, 为混凝土抗冲击工程设计提供了参考依据. 关键词： 冲击 混凝土 SHPB 摩擦力     

Nonclassical state via superposition of two coherent states (π/2 out of phase) and related entangled states

Nonclassical features of the superposition of two coherent states which are π/2 out of phase are discussed, such as sub-Poissonian photon statistics and quadrature squeezing, as well as negativity of the Wigner function. Special nonclassicality is found in the special state where the relative phase of superposition has relationship with the average photon number. The analysis of the amount of entanglement is also presented for the related two-mode entangled coherent states.     

The effect of electronic orbital interactions on p-type doping tendency in ZnO series： First-principles calculations

The electronic structures and optical properties of B3 ZnO series of Znelectronic structures, optical properties, pseudopotential plane-wave method, \\ \hspace*{1.9cm} p-type doping tendency,electronic structures, optical properties, pseudopotential plane-wave method, \\ \hspace*{1.9cm} p-type doping tendencyProject supported by the National Natural Science Foundation of China (Grant No~10625416).2007-04-252007-06-18The electronic structures and optical properties of B3 ZnO series of Zn4X4-yMy（X ：O, S, Se or Te; M = N, Sb, C1 or I; y = 0 or 1） are studied by first-principles calculations using a pseudopotential plane-wave method. The results show that Zn d-X p orbital interactions play an important role in the p-type doping tendency in zinc-based Ⅱ-Ⅵ semiconductors. In ZnX, with increasing atomic number of X, Zn d-X p orbital interactions decrease and Zn s-X p orbital interactions increase. Additionally, substituting group-V elements for X will reduce the Zn d-X p orbital interactions while substituting group-VII elements for X will increase the Zn d-X p orbital interactions. The results also show that group-V-doped ZnX and group-Ⅷ-doped ZnX exhibit different optical behaviours due to their different orbital interaction effects.     

One-step green route to narrowly dispersed copper nanocrystals

We report a total “green” chemical method in aqueous solution for synthesizing stable narrowly distributed copper nanoparticles with average diameter less than 5 nm in the presence of Polyvinylpyrrolidone (PVP) as a stabilizer and without any inert gas protection. In our synthesis route, ascorbic acid, natural vitamin C (VC), an excellent oxygen scavenger, acts as both reducing agent and antioxidant, to reduce the metallic ion precursor, and to effectively prevent the common oxidation process of the newborn pure copper nanoclusters.