Comparative studies of AOT and NaDEHP by fluorescence technique and z-potential (ζ) measurements

The aggregation behaviors of two surfactants with the same hydrophobic tail, sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP), have been investigated by the fluorescence technique and z-potential (ζ) measurements. Five fine peaks of the pyrene molecule fluorescence spectroscopy appear in the surfactant solution, and the micropolarity at which pyrene locates is monitored from the intensity ratio of the first (I1) and the third peak (I3). A wide peak around 475 nm, the emission spectra of the excimer of pyrene molecules, is observed in the NaDEHP solution, while this is not found for the AOT system. The value of I1/I3 decreases in a more limited concentration range for the AOT system than for NaDEHP, indicating that small aggregates can be more easily formed by NaDEHP molecules. The z-potential results for the aggregates formed by the two surfactants show that the interaction between AOT and PVP is stronger than that between NaDEHP and PVP.

Gal(1-x)Mn(1-x)Sb Grown on GaSb with Mass-Analyzed Low-Energy Dual Ion Beam Deposition

The Ga1-xMnxSb samples were fabricated by the implantation of Mn ions into GaSb (1 0 0) substrate with mass-analyzed low-energy dual ion beam deposition system, and post-annealing. Auger electron spectroscopy depth profile of the Ga1-xMnxSb samples showed

Laser drilling improving circuit board manufacturing

We reported here a novel technique for laser high speed drillings on Printed Circuit Boards (PCBs). A CNC solid laser based system is developed to drill through and blind vias as an alternative to mechanical drilling. The system employs an Acousto-Optic Q-switched Nd: YAG laser, a computer control system and an X-Y moving table which can handle up to 400 x 400 mm PCB. With a special designed cavity the laser system works in a pulsed operation in order to generate pulses with width down to 0.5 mu s and maximum peak power over 10kW at 10k repetition rate. Delivered by an improved optical beam transforming system, the focused laser beam can drill hobs including blind vias on PCBs with diameter in the range of 0.1 - 0.4 mm and at up to 300 - 500 vias per second (depending on the construction of PCBs). By means of a CNC X-Y moving system, laser pulses with pulse-to-pulse superior repeatability can be fired at desired location on a PCBs with high accuracy. This alternative technology for drilling through or blind vias on PCBs or PWBs (printed wiring boards) will obviously enhance the capability to printed boards manufacturing.

Electron Beam Surface Remelting of AISI D2 Cold-Worked Die Steel

Electron beam surface remelting has been carried out on AISI D2 cold-worked die steel. The microstructure and hardening behavior of the electron beam surface remelted AISI D2 cold-worked die steel have been studied by means of optical microscopy and Vickers hardness testing. It was found that AISI D2 steel can be successfully surface hardened by electron beam surface remelting. This surface hardening effect can be attributed to microstructural refinement following electron beam surface remelting. (C) 2002 Elsevier Science B.V. All rights reserved.

Optical fringe multiplication technique with TEM nano-moiré method

In this paper, a nano-moiré fringe multiplication method is proposed, which can be used to measure nano-deformation of single crystal materials. The lattice structure of Si (111) is recorded on a film at a given magnification under a transmission microscope, which acts as a specimen grating. A parallel grating (binary type) on glass or film is selected as a reference grating. A multiplied nano-moiré fringe pattern can be reproduced in a 4f optical filter system with the specimen grating and the prepared reference grating. The successful results illustrate that this method can be used to measure deformation in nanometre scale. The method is especially useful in the measurement of the inhomogeneous displacement field, and can be utilized to characterize nano-mechanical behaviour of materials such as dislocation and atomic bond failure.

Size effects in the constrained deformation of metallic foams

The constrained deformation of an aluminium alloy foam sandwiched between steel substrates has been investigated. The sandwich plates are subjected to through-thickness shear and normal loading, and it is found that the face sheets constrain the foam against plastic deformation and result in a size effect: the yield strength increases with diminishing thickness of foam layer. The strain distribution across the foam core has been measured by a visual strain mapping technique, and a boundary layer of reduced straining was observed adjacent to the face sheets. The deformation response of the aluminium foam layer was modelled by the elastic-plastic finite element analysis of regular and irregular two dimensional honeycombs, bonded to rigid face sheets; in the simulations, the rotation of the boundary nodes of the cell-wall beam elements was set to zero to simulate full constraint from the rigid face sheets. It is found that the regular honeycomb under-estimates the size effect whereas the irregular honeycomb provides a faithful representation of both the observed size effect and the observed strain profile through the foam layer. Additionally, a compressible version of the Fleck-Hutchinson strain gradient theory was used to predict the size effect; by identifying the cell edge length as the relevant microstructural length scale the strain gradient model is able to reproduce the observed strain profiles across the layer and the thickness dependence of strength. © 2002 Elsevier Science Ltd. All rights reserved.

Material parameter extraction in THz-TDS using a converging beam transfer function

We demonstrate a parameter extraction algorithm based on a theoretical transfer function, which takes into account a converging THz beam. Using this, we successfully extract material parameters from data obtained for a quartz sample with a THz time domain spectrometer. © 2010 IEEE.

Numerical Simulation on the Micro-Scale Bending Induced by Pulsed Laser Beam

利用自行研制的含热传导、冲击动力学大、变形有限元程序,模拟了小尺寸梁在脉冲激光加热条件下的变形过程。在此基础上,利用商用程序模拟了冷却及残余应力的产生,研究了激光参数（强度及分布）等对于微弯曲的影响。数值模拟结果与文献中的实验观察相吻合。