Breath figures-mediated microprinting allows for versatile applications in molecular biology

Softlithographic processes are currently applied in different fields ranging from microelectronics to biology. One of the main advantages of these techniques stands in the low cost and in its easy use without the need of expensive apparatus. The available procedure is simple and particularly suitable for biological tests: a biomolecule is printed on a suitable substrate and its presence can be further recognized with a given reactants. The use of polydimethylsiloxane (PDMS) is a key step in this technology because printing from PDMS mould is an easy process. We have recently shown that the hexagonal ordered pattern which is obtained by breath figure method on a polystyrene film, generated by arrangements of micrometric holes on the film surface, can be reproduced by PDMS obtaining a positive mould, formed by regularly arranged micrometric protuberances. This mould can be “inked” with a suitable biomolecule solution which is subsequently printed on the desired substrate. With this method no photolithographic step is necessary; regular spots of a few microns can be easily produced without the need of sophisticated apparatus. We report some examples of printing with different molecules which are then recognized by specific reactants. A further advantage of the method we present in this work is related to the multiple printing of the same labelled molecule with the same mould onto several substrates without significant loss of signal.     

中国散裂中子源直线加速器丝靶扫描器的设计与模拟

In this paper, we report the design and simulation of a wire scanner for the linac of the CSNS （China Spallation Neutron Source）. The wire scanner is used to measure the transverse beam profile and the emittance. The effect of beam energy change upon the mechanical design of the wire scanner must be considered. The simulation results of heat on the two specified wires, tungsten and carbon, by using the finite element method software, ANSYS, are presented. In addition, the effect of wire deformation on the beam profile measurement is qualitatively analyzed, and the signal level of the wire scanner is discussed.     

Study of liquid deposition during laser printing of liquids

Laser-induced forward transfer (LIFT) is a direct-writing technique which can be used to successfully print various complex and sensitive materials with a high degree of spatial resolution. However, the optimization of its performances requires a deep understanding of the LIFT dynamics. Such understanding should allow correlating the phenomena underlying the liquid transfer process with the morphology of the obtained deposits. To this end, in this work it is presented a study related to two aspects: first, the correlation of the morphological characteristics of the transferred droplets with the variation of the film thickness combined with laser fluence; and second, a correlation of the dependences observed with the dynamics of the transfer process. The work is focused on the understanding of the observed dependences for which the information provided by time-resolved analysis on liquid transfer dynamics has proved to be crucial.     

指纹采集仪混频现象的研究

由于图像传感器的采样不足,在指纹仪成像质量检测中高频区域出现了混频现象。为了避免混频,提高指纹仪的成像质量,提出了指纹仪出现混频的区域。描述了指纹采集仪出现的混频现象,通过理论分析和计算,获得了指纹仪的混频区域。对实验得到的图像所出现的混频区域进行了测量,测量结果与理论计算结果基本一致。     

Effect of Interference on Scanning Performance of fθ Lens Fixed by a Shrink Fitter

An ultra-precise method of joining optical lenses in a housing by a shrinkage fit has been developed using a shrink fitter, which is a cylindrically shaped machine element made of a plastic material. In this method, the form error of the shrink fitter increased the interference of shrinkage fit which caused a lens deformation much greater than the limitation of surface irregularity of λ/2. With an fθ lens unit of the laser scanner, this lens deformation may deteriorate the laser beam spots on an image plane. Therefore, the shrink fitter is carefully and precisely turned, however this takes time and costs money. This is a contact problem between the optical lenses and the shrink fitter. In this paper, to determine limit interferences of the shrink fitter, the effect of the interference of the shrinkage fit on the scanning performance was examined through computer simulation.     

二维定心激光扫描器及其摆角测量系统的研制

简要介绍了一种二维定心偏转激光扫描器的工作原理和结构设计。对二维摆角的两种不同测量方式的优劣进行了比较,并详细介绍了采用光电位置传感器(PSD)实现摆角测量的系统,包括它的测量原理、光学系统构造和PSD后续信号处理电路。结果表明,所研制的二维定心激光扫描器摆角测量系统可以实现±7.5°的二维摆角和30°圆锥角的大范围扫描,其重复精度为0 05°,分辨率为0 01°。具有快速灵巧、实时性强、工作稳定、抗环境干扰能力强等优点。     

薄层色谱扫描仪检定方法探讨

为了解决薄层色谱扫描仪没有统一的量值溯源方法和标准装置的问题,建立薄层色谱扫描仪检定方法。通过对薄层色谱扫描仪各部分的结构进行分析,建立了薄层色谱扫描仪检定项目及计量性能要求。采用低压汞灯为标准器进行波长示值误差和重复性检定,采用薄层色谱标准板进行仪器重复性和线性检定。该检定方法能准确评价薄层色谱扫描仪的性能,为薄层色谱扫描仪的量值溯源提供技术支持。     

A L1-regularized feature selection method for local dimension reduction on microarray data

Dimension reduction is a crucial technique in machine learning and data mining, which is widely used in areas of medicine, bioinformatics and genetics. In this paper, we propose a two-stage local dimension reduction approach for classification on microarray data. In first stage, a new L1-regularized feature selection method is defined to remove irrelevant and redundant features and to select the important features (biomarkers). In the next stage, PLS-based feature extraction is implemented on the selected features to extract synthesis features that best reflect discriminating characteristics for classification. The suitability of the proposal is demonstrated in an empirical study done with ten widely used microarray datasets, and the results show its effectiveness and competitiveness compared with four state-of-the-art methods. The experimental results on St Jude dataset shows that our method can be effectively applied to microarray data analysis for subtype prediction and the discovery of gene coexpression.     

扫描仪精确标定与基于扫描图像的精密测量

分析了普通平板扫描仪扫描过程中引入畸变误差的成因和特点，提出并实现了用分布于待测图像四周的正交网格对包括待测图像在内的全场进行标定的方法和算法．标定后精度提高一个数量级以上，全场几何标准偏差在2—3微米以内，使普通扫描仪可用于精度要求极高的工程测量．用扫描仪将干板等介质记录的图像数字化，通过标定，修正扫描过程中引入的畸变误差，即可利用数字图像处理技术进行自动和半自动的精密测量．