Long pulse generation technology of solid-state laser adopting a new real time multi-discharge method

In this study, a solid-state laser system adopting a new real time multi-discharge method in which three flashlamps are turned on consecutively was designed and fabricated to examine the pulse width and the pulse shape of the laser beams depending upon the changes in the lamp turn-on time. That is, this study shows a technology that makes it possible to make various pulse shapes by turning on three flashlamps consecutively on a real-time basis with the aid of a program integrated circuit one-chip microprocessor. With this technique, the lamp turn-on delay time can be varied more diversely from 0 to 10 ms and the real-time control is possible with an external keyboard, enabling various pulse shapes. In addition, longer pulses can be more widely used for industrial processing and many medical purposes.     

Comparative Study of Plasma Spray Flow Fields and Particle Behavior Near to Flat Inclined Substrates

Numerical models have been developed using computational fluid dynamics (CFD) analysis program FLUENT V6.02^© to investigate the effect of the substrate on the behavior of the plasma flow fields and in-flight particles. Simulations are performed for cases where flat substrates are either present or absent, for the former, the substrate is oriented perpendicularly or inclined to the torch axis. It is shown that although the presence of perpendicular or inclined substrate significantly influences the plasma flow fields at the vicinity of the substrate, the particle behavior remain relatively unaffected. The insignificant effect of the substrate on particle behavior is qualitatively verified by experimental observation using SprayWatch^© imaging diagnostics equipment. Images captured by the equipment confirm that the particles travel through the plasma plume with high momentum and show no sudden change in theirtrajectories right before impacting the substrate. Both the numerical and experimental findings show that the freestream model is sufficiently detailed for future work of this nature.     

Polymer-stabilized cholesteric liquid crystal microgratings: a comparison of polymer network formation and electro-optic properties for mesogenic and non-mesogenic monomers

Polymer-stabilized liquid crystal microgratings are made using a focused Gaussian UV laser beam to photopolymerize 3 wt % reactive monomer in a cholesteric liquid crystal host. In a typical case, round gratings of 300 μm diameter and 10 μm pitch are produced. The microgratings highlight interesting differences between mesogenic and non-mesogenic monomers in the assembly and spatial distribution of polymer networks formed in a cholesteric host. We also observe a corresponding variation in the electro-optical properties of the stabilized gratings. In the mesogenic case, the grating state of the liquid crystal is faithfully captured even for relatively short UV exposures and over regions only a few pitch lengths in size. These findings are consistent with phase separation of the mesogenic monomer into regular domains templated by periodic, macroscopic variations in orientational order of the host. This templating effect is significantly reduced in the non-mesogenic case.     

片状纳米NiO的制备及其电化学电容性能

电化学电容器又名超级电容器,是近年来出现的一种新型储能器件,已起了人们的广泛关注[1-3].本工作采用改良沉淀法制备了Ni(OH)2粉末,并通过热处理得到纳米NiO材料,研究了其电化学电容性能.实验所制备的纳米NiO比容量值高达1081F/g.     

Microwave-assisted synthesis of (η-arene)tricarbonylchromium complexes

We have undertaken a study of the microwave-assisted synthesis of (η⁶-arene)tricarbonylchromium complexes. Under microwave irradiation, the reactions of hexacarbonylchromium with arenes gave high yields of (η⁶-arene)chromium tricarbonyl complexes.     

聚氨酯基层状硅酸盐纳米复合物研究进展

具有优良综合性能的聚合物基层状硅酸盐纳米复合物是当前材料科学研究的重要方向。本文介绍了以聚氨酯材料为基质的聚合物基层状硅酸盐纳米复合物的制备技术、表征手段、物理化学性能以及结构形态,对该复合材料的工业开发前景、国内外研究现状以及发展趋势进行了分析。     

一种奇异临界椭圆方程的非平凡解

该文研究了一类带有Sobolev-Hardy临界指数的半线性椭圆方程,运用变分理论中的环绕定理证明了方程非平凡解的存在性     

White electroluminescence from a single polyfluorene containing bis‐DCM units

A series of fluorene‐based copolymers composed of blue‐ and orange‐light‐emitting comonomers were synthesized through palladium‐catalyzed Suzuki coupling reactions. 9,9‐Dihexylfluorene and 2‐(2,6‐bis‐{2‐[1‐(9,9‐dihexyl‐9H‐fluoren‐2‐yl)‐1,2,3,4‐tetrahydroquinolin‐6‐yl]‐vinyl}‐pyran‐4‐ylidene)‐malononitrile (DCMF) were used as the blue‐ and orange‐light‐emitting chromophores, respectively. The resulting single polymers exhibited simultaneous blue (423/450 nm) and orange (580–600 nm) emissions from these two chromophores. By adjusting the fluorene and DCMF contents, white light emission could be obtained from a single polymer; a device with an ITO/PEDOT:PSS/polymer/Ca/Al configuration was found to exhibit pure white electroluminescence with Commission Internationale de L'Eclairage (CIE) coordinates of (0.33, 0.31), a maximum brightness of 1180 cd/m², and a current efficiency of 0.60 cd/A. Furthermore, the white light emission of this device was found to be very stable with respect to variation of the driving voltage. The CIE coordinates of the device were (0.32, 0.29), (0.32, 0.29), and (0.33, 0.31) for driving voltages of 7, 8, and 10 V, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3380–3390, 2007     

Y2SiO5:Tb phosphor particles prepared from colloidal and aqueous solutions by spray pyrolysis

Green-emitting Y₂SiO₅:Tb phosphor particles with fine size, spherical shape, filled morphology, high crystallinity, and good brightness were synthesized by a spray pyrolysis process. The effect of silicon precursor type on the morphology, crystal structure, crystallinity, and photoluminescence efficiency of Y₂SiO₅:Tb phosphor particles was investigated. The particles prepared from an artificial colloidal solution obtained by dispersing fumed silica particles had a pure monoclinic X2 crystalline phase, which is more appropriate for application to displays, after post-treatment at 1300 °C. On the other hand, the particles prepared from 100% tetraethyl orthosilicate (TEOS) reagent had an X2 phase and small amounts of X1 and impurity phases such as Y₂Si₂O₇ and Y_4.67Si₃O₁₃ due to the phase-segregation characteristics of the TEOS precursor. The photoluminescence characteristics of Y₂SiO₅:Tb phosphor particles were strongly affected by the silicon source used. The photoluminescence intensities increased with the fumed silica/TEOS ratio. The particles prepared from 100% fumed silica showed the maximum photoluminescence intensity, which is 22% higher than that of particles prepared from 100% TEOS. PACS 81.20.Rg; 78.55.Hx; 78.40.Ha; 81.05.Hd; 81.40.Tv     

Simulation of Optical Devices Using Parallel FDTD Method

On this paper, we investigate the algorithm and efficiency of simulation of optical devices using parallel computing method, implement some real wavelength division multiplexing (WDM) components such as resonators to test the method's possibility and efficiency.