Ultraviolet generation tunable to 0.185 microm in CsLiB6O10

CsLiB(6) O(10) has been found to be phase matchable for type-1 sum frequency generation to a minimum of 0.185 mum by mixing the fifth harmonic of a Nd:YAG laser at 1.0642 mum and the output of a KTP parametric oscillator pumped by the second harmonic of the same Nd:YAG laser at 20.0 degrees C. The improved Sellmeier equations and the thermo-optic constants of this crystal are reported.     

Sum-Frequency Generation of Femtosecond Pulses in CsLiB(6)O(10) Down to 175 nm

Using a 150-mum-thick CsLiB(6)O(10) crystal, we produced 100-fs, >200-nJ light pulses tunable between 175 and 180 nm by sum-frequency generation at a 1-kHz repetition rate with an all-solid-state laser system mixing the fourth harmonic of a femtosecond Ti:sapphire regenerative amplifier and the idler pulse from a traveling-wave optical parametric amplifier.     

Optical second harmonic generation in CsLiB6O10 nanocrystallites incorporated to the olygoether photopolymer matrices induced by acustical field

Optical second harmonic generation in CsLiB₆O₁₀ (CLBO) large-sized nanocrystallites (15–40 nm) incorporated into the olygoether photopolymer matrices has been found at liquid helium temperature (LHeT). The second harmonic generation (SHG) has been measured for the source wavelength of the YAG : Nd laser ( = 1.06 m). Increasing acoustical power (up to 18.1 W/cm²) and acoustical frequencies at 14 kHz give maximal values of the output SHG. The measured SHG ₂₂₂ tensor component was comparable with the one for the traditional nonlinear optical crystals such as KH₂PO₄, KTiOPO₄, LiNbO₃. With decreasing temperature below 28 K the acoustically induced SHG signal strongly increases. A correlation between the acoustically induced SHG and low-frequency Raman modes has been found. The maximal acoustically induced SHG has been observed for the nanocrystallite concentration about 3.1% (in weighting units) and the crystallite sizes lying within the 35–40 nm. The SHG tensor coefficients were higher than for the proper CLBO crystals at least on the 13%. Advantageous and drawbacks of the presented model are discussed. The theory of the observed phenomena is explained on the ground of ab initio band energy calculations with taking into account of anharmonic electron-phonon interactions.     

基于双纵模热稳频激光源的6D激光测量系统

针对目前数控设备无法实现高速及多参数同时测量的问题,以双纵模热稳频激光源为基础,自主研发了高速6D激光测量系统,不仅允许测速高(可达1.3m/s以上),而且解决了现有5D/6D激光干涉仪未能有效解决的高精度测量滚转角的问题,具有很好的推广应用价值.     

Hydrothermal-induced growth of Ca10V6O25 crystals with various morphologies in a strong basic medium at different temperatures

The Ca₁₀V₆O₂₅ crystals with various morphologies were synthesized by a facile hydrothermal method in a strong basic medium. The effects of the pH of synthesizing solution, hydrothermal reaction temperature and time on the morphology and crystallinity of Ca₁₀V₆O₂₅ powders were investigated. The as-synthesized powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–vis spectrophotometer and vibrating sample magnetometer. The experimental results demonstrate that phase-pure Ca₁₀V₆O₂₅ powders could be hydrothermally obtained at temperatures ranging from 120 °C to 180 °C for 12–48 h with the pH ≥ 12.5 of synthesizing solution. The morphology of Ca₁₀V₆O₂₅ powders was strongly dependent on the synthesis parameters, such as pH, temperature and time. The Ca₁₀V₆O₂₅ microspheres were obtained at 180 °C for 48 h with the pH = 12.5 of synthesizing solution. The UV–vis diffuse reflectance spectra have shown that the Ca₁₀V₆O₂₅ powders efficiently absorb UV light with an absorption edge at about 380 nm. All the samples noticeably exhibit a superparamagnetic behavior with a nearly zero magnetic remanence (remanent magnetization). The hydrothermally synthesized Ca₁₀V₆O₂₅ powders may be employed as a potential candidate in novel electronic and biomedical applications.     

基于MSComm控件下的激光跟踪系统串口通信研究

为了实现控制台对激光跟踪系统的测量控制,设计了一种基于MSComm控件下的串口通信.控制台与激光跟踪仪之间采用了两个串口进行连接,通信协议为RS422,串口一发出触发信号,串口二进行信号采集,整个编程环境在Delphi下进行,程序中通过MSComm控件采集信号和对信号进行处理,给出了程序部分关键代码.通过实验测量,程序运行良好,最终达到了对激光跟踪仪角度信号的提取和对被测物体角度测量的目的,系统有良好的测量精度和灵敏度.     

Optimization of the contrast, brightness, and modulation amplitude of light in electrooptic devices based on polymer-encapsulated ferroelectric liquid crystals

An analysis is made of the relations connecting the maximum optical transmittance, the light modulation amplitude, and the contrast in a polymer-encapsulated ferroelectric liquid-crystal device to the geometry of device and the tilt angle θ of the director. The correctness of the calculations is confirmed by their agreement with experimental measurements. Pis’ma Zh. Tekh. Fiz. 24, 63–67 (June 26, 1998)     

The crystallisation of glasses based on eutectic compositions in the system Li2O-Al2O3-SiO2

Structural transformations have been studied in glasses related in composition to the binary eutectic between lithium metasilicate and -spodumene. Crystallisation processes and changes in microstructure during the controlled heating of the glasses have been followed using X-ray diffraction, electron microscopy, high temperature microscopy, thermal analysis and electron spin resonance spectroscopy.The influence exerted by titanium dioxide on the phase relationships, crystal growth rates and micromorphology of the polycrystalline products of heat-treatment has been investigated and the findings used as a basis for proposals on the rôle of TiO₂ during nucleation and crystal growth.     

The crystallisation of glasses based on the eutectic compositions in the system Li2O-Al2O3-SiO2

A study has been made of the crystallisation of glasses based on the eutectic between lithium metasilicate and-eucryptite and of the rÔle of TiO₂ in promoting fine-grained crystallisation. The hypothesis advanced in part 1 of this work is extended to a semi-quantitative measure of the effect of TiO₂.Characteristics of two metastable phases are described in an appendix.     

Electrical conduction in the system Sr0·90La0·10Ti0·90M′0·10O3 (M′ = Co,Ni or Cr)

We have successfully synthesized the system Sr_{1 −x} La _x Ti_{1 −x} M′ _x O₃ where M′ = Cr, Ni and Co by using conventional solid state ceramic method. Powder X-ray diffraction patterns of the different compositions show the formation of single phase materials. Measurement of AC conductivity as a function of frequency at different temperatures in the range 300–550 K show that conduction in these compositions occurs due to hopping of charge carriers between localized transition metal ion sites.     

Growth of larger crystals of ZSM-5 in the system 4(TPA)2O-38(NH4)2O-x(Li,Na,K)2 O-A12O3-59SiO2-750H2O

The synthesis of zeolite TPA-ZSM-5 with (NH₄)₂O/Al₂O₃ = 38 and different amounts of Li₂O, Na₂O or K₂O was studied. Kinetic crystallization data and the growth of the crystals as a function of time are reported. The results show an increment of the size of the crystals when alkali metal oxide is added to the system. With Li₂O, unusually uniform, large, lathshaped crystals of ZSM-5 ∼ 140 ± 10 μm in length were obtained. The time of nucleation is long when only (NH₄)₂O is used with TPA and decreases when alkali metal oxide is added to the system.     

分子印迹氨基功能化纳米Fe_3O_4高分子磁性复合材料的合成及其对海水中2,4,6-三氯苯酚的吸附性能

为了实现海水中2,4,6-三氯苯酚(2,4,6-TCP)的选择性吸附和去除,采用超声协助悬浮聚合法以2,4,6-三氯苯酚为模板制备了分子印迹氨基功能化纳米Fe3O4高分子磁性复合材料(nFe3O4@MIPNH2-polymer)。通过元素分析(EA)、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱分析、透射电子显微镜(TEM)、振动样品磁强计(VSM)等手段对nFe3O4@MIPNH2-polymer的组成、结构、形貌、磁性等进行表征,并研究了其应用于吸附和去除海水中2,4,6-三氯苯酚(2,4,6-TCP)污染物的性能。结果表明:合成的nFe3O4@MIPNH2-polymer平均粒径约为800nm,饱和磁化强度为32.6emu·g-1;水溶液中2,4,6-TCP的饱和吸附量为105.26mg·g-1,高于非分子印迹氨基功能化纳米Fe3O4高分子磁性复合材料(nFe3O4@NH2-polymer)的饱和吸附量(76.92mg·g-1),nFe3O4@MIPNH2-polymer对2,4,6-TCP的等温吸附线大体符合Langmuir模型。吸附热力学研究表明,nFe3O4@MIPNH2-polymer对2,4,6-TCP的吸附过程是自发的吸热熵增过程;吸附过程可在5min内达到平衡,动力学数据和准二级动力学模型符合较好;其吸附过程去除2,4,6-TCP的活化能为78.0kJ·mol-1。海水中的共存物质对吸附2,4,6-TCP几乎无干扰,nFe3O4@MIPNH2-polymer经洗脱后可以循环使用5次以上。nFe3O4@MIPNH2-polymer能高选择性地有效去除海水中的2,4,6-TCP。     

Control policy simulation based on machine age in a failure prone one-machine,one-product manufacturing system

This paper deals with the production planning problem of a flexible manufacturing system (FMS). This problem is within the class of problems which are usually faced during the life cycle of FMS. There are basically two approaches used to solve this problem: analytical and simulation. The objective of this paper is to develop a methodology for determine the control policy for a given FMS by using the combination of both analytical and simulation approaches. The production rate control of a one-machine one-product system is presented to illustrate our approach. The contribution of the analytical part of the proposed model consists of generating a near-optimal controller based on the concept of an age-dependent hedging point policy. This sub-optimal policy is used as input of the simulation part and the improvement of operating conditions (control policies) achieved with a constant demand rate. The proposed model includes also a stochastic demand and lot sizes in production which consists of similar products batches with bulk arrivals. The robustness of the controller against both demand rates and production types has been validated.     

Novel alkali-resistant porous glass prepared from a mother glass based on the SiO2-B2O3-RO-ZrO2 (R = Mg,Ca, Sr,Ba and Zn) system

The alkali-resistant porous glass was prepared from the Si0₂-B₂0₃-RO (R=Mg, Ca, Sr, Ba and Zn) system containing Zr0₂. The porous glass skeleton contained 2–3 mass% Zr0₂ and the alkali resistance was greatly improved over that of ordinary Vycor-type porous glass. Because of the high alkali resistance, the elimination of the colloidal Si0₂ and Zr0₂ gelated during the acid leaching of the phase-separated glass, was promoted and as a result, a very sharp pore-size distribution of porous glass was attained. In addition, the limit of the available pore size of porous glass was widely expanded.     

XANES Study on the Evolution Among Different Copper Species, CuI, CuII and CuIII, in CuBa2YCu2O6+z Upon Oxygen Loading

X-ray absorption near-edge structure (XANES) spectroscopy at the Cu L-edge is applied to follow the gradual formation of Cu^II and Cu^III species from Cu^I with increasing amount of excess oxygen, z, in Cu(1)Ba₂YCu(2)₂O_6+z . For the study, a series of samples with precisely controlled oxygen contents was prepared utilizing the temperature-controlled oxygen-depletion (TCOD) annealing technique in the sample synthesis and employing coulometric titration for accurate oxygen-content analysis. It may be concluded that at low amounts of excess oxygen, z, Cu(1)^I in the charge reservoir tends to be first oxidized to Cu(1)^II rather than directly to Cu(1)^III, suggesting that complete chain formation does not occur at low oxygen contents.     

XANES Study on the Evolution Among Different Copper Species, CuI, CuII and CuIII, in CuBa2YCu2O6+z Upon Oxygen Loading

X-ray absorption near-edge structure (XANES) spectroscopy at the Cu L-edge is applied to follow the gradual formation of Cu^II and Cu^III species from the Cu^I species with increasing amount of excess oxygen, z, in Cu(1)Ba₂YCu(2)₂O_6+z . For the study, a series of samples with precisely controlled oxygen contents was prepared utilizing the temperature-controlled oxygen-depletion (TCOD) annealing technique in the sample synthesis and employing coulometric titration for accurate oxygen-content analysis. It may be concluded that at low amounts of excess oxygen, z, Cu(1)^I in the charge-reservoir tends to be first oxidized to Cu(1)^II rather than directly to Cu(1)^III, suggesting that complete chain formation does not occur at low oxygen contents.     

Novel active heterogeneous Fenton system based on Fe3-xMxO4 (Fe, Co, Mn, Ni): the role of M2+ species on the reactivity towards H2O2 reactions

In this work, the effect of incorporation of M2+ species, i.e. Co2+, Mn2+ and Ni2+, into the magnetite structure to increase the reactivity towards H2O2 reactions was investigated. The following magnetites Fe3-xMnxO4, Fe3-xCoxO4 and Fe3-xNixO4 and the iron oxides Fe3O4, gamma-Fe2O3 and alpha-Fe2O3 were prepared and characterized by M?ssbauer spectroscopy, XRD, BET surface area, magnetization and chemical analyses. The obtained results showed that the M2+ species at the octahedral site in the magnetite strongly affects the reactivity towards H2O2, i.e. (i) the peroxide decomposition to O2 and (ii) the oxidation of organic molecules, such as the dye methylene blue and chlorobenzene in aqueous medium. Experiments with maghemite, gamma-Fe2O3 and hematite, alpha-Fe2O3, showed very low activities compared to Fe3O4, suggesting that the presence of Fe2+ in the oxide plays an important role for the activation of H2O2. The presence of Co or Mn in the magnetite structure produced a remarkable increase in the reactivity, whereas Ni inhibited the H2O2 reactions. The obtained results suggest a surface initiated reaction involving Msurf2+ (Fe, Co or Mn), producing HO radicals, which can lead to two competitive reactions, i.e. the decomposition of H2O2 or the oxidation of organics present in the aqueous medium. The unique effect of Co and Mn is discussed in terms of the thermodynamically favorable Cosurf3+ and Mnsurf3+ reduction by Femagnetite2+ regenerating the active species M2+.