Monomer compartmentalisation in miniemulsion polymerisation studied by infrared spectroscopy

Miniemulsion polymerisations of styrene and butyl methacrylate were carried out in order to study mass transfer during the reaction. An in-line Attenuated Total Reflectance–Fourier Transform Infrared (ATR–FTIR) probe was used to follow the reactions, and the collected spectra were used to identify the different species that appeared and disappeared during polymerisation. The results show that the droplets were completely compartmentalized during the reaction, and that even when blends of droplets with different composition were polymerised together, no detectable levels of copolymer were formed. To cite this article: K. Ouzineb et al., C. R. Chimie 6 (2003).     

在全息照相实验中增设光栅辅助白光再现全息图的尝试

针对目前大多数理工科院校开设的全息照相实验中一般只用单色光再现的现状,在保留单色光再现的基础上,增加了光栅辅助白光再现实验内容,丰富了实验内容和提升了实验层次,加深了学生对全息术理论和光栅衍射的理解.     

用两束物光束拍摄漫反射全息照相

指出了一般的漫反射全息照相光路的缺点，提出了用2束物光束拍摄漫反射全息照相的改进方案。     

Total Integration of the Sample Injection,Microdroplet Reaction,Phase Separation,Real-Time Optical Detection,and Recovery of Diverse Silver–Gold Bimetallic Nanoalloys in a Continuous Process

Microfluidic droplet generators have garnered great attention due to the uniformity, high-throughput capability, and facile experimental setup. To maximize the potentials of droplet technology as a chemical/biological nanoliter-scale reactor, the downstream processes such as separation of the aqueous and oil phase, real-time monitoring of the products formed in droplets, and the final product recovery from the droplets is necessary. In this study, the droplet is utilized as a chemical reactor to synthesize a variety of Ag and Au bimetallic nanoalloys in a fully integrated microsystem including sample injection, a T-junction droplet generator, droplet reaction, water–oil phase separation, real-time UV–vis absorbance detection, and product recovery. The flow rate of the Ag nanoparticle (NP) solution and the HAuCl₄ solution was tuned to generate different molar ratios of Ag and Au components. The in-line UV–vis absorbance spectrometer displays a peak shift of the Ag/Au bimetallic alloys depending on the molar ratio of Ag/Au in the continuous process, enabling to judge the kind of the Ag/Au alloys in situ and collect a variety of Ag/Au nanoalloys. Thus, the desired nanomaterials can be obtained with minimal trial and error, saving time and cost.     

高频可变间距全息光栅的制作方法的计算机模拟研究

提出了一种制作高频线性可变频率光栅的新方法，并给出了光栅空间频率的表达式.通过在相干的两光路中插入特殊透镜，可以实现线性可变空间频率光栅的制作，而且通过适当地调节实验参数可以改变空间频率的变化率.给出了相应的模拟全息图. 关键词： 全息光栅 全息 可变间距光栅     

超短脉冲数字全息术中的立体角分复用技术

将角分复用技术应用于超短脉冲数字全息术，可实现对超快过程的动态记录.其中，在角分复用的设计中，由于CCD像素尺寸的限制，一般对物光和参考光的角度要求较为苛刻.为此，提出了一种立体角分复用的方法，并使用连续激光数字全息实验验证了这种方法的有效性.在此基础上，根据超短脉冲数字全息术记录超快过程的特点，设计了能够实现自动连续进行立体角分复用记录的光路.计算分析表明，该光路可在一帧数字全息图上连续记录间隔为纳秒量级的多幅超快过程的动态图像. 关键词： 超短脉冲数字全息术 立体角分复用 超快过程     

Soft X-Ray Holographic Microscopy of Biological Cells

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IN-LINE MEASUREMENT OF PARTICLE SIZE AND CONCENTRATION WITH LIGHT FLUCTUATION METHOD

This paper presents a new method for in-line and in-situ particle sizing based on the Light Fluctuation Method, including the development of a novel optical probe capable of measuring particle size and concentration in the broad range of 10～1000 microns.     

Direct analysis of in-line particle holograms by using wavelet transform and envelope reconstruction method

We propose a new digital method for sizing particles and tracking their positions from an in-line hologram by using a combination of a wavelet transform and a reconstruction of the envelope functions. In the proposed method, the hologram is recorded by a charge-coupled device (CCD) sensor. The wavelet transform of digitized holograms gives information about the position of particles, while the reconstruction of envelope functions provides the size of particles. Preliminary theoretical and experimental verifications are presented. The system limitation of the method is discussed.     

Digital in-line holography for the characterization of flowing particles in astigmatic optical systems

An extended Generalized Fresnel Transform (GFT) is proposed to account for the astigmatism introduced by optical elements described, in the paraxial approximation, with a ray transfer matrix analysis. Generalized impulse response and generalized Fresnel transfer function propagators as well as sampling conditions are derived to properly implement this transformation. As a test case, the near-field diffraction patterns and in-line holograms produced by droplets flowing in a tube with cylindrical interfaces have been simulated. A best fitting approach is introduced to retrieve, from the propagated holograms, the 3D position and size of the droplets. Several hologram focusing indicators based on the analysis of droplets focus region are also proposed to further improve the estimation of the droplets position along the optical axis. Numerical simulations and experimental results confirm the applicability and accuracy of the proposed methods.