碘化钾-镉(Ⅱ)-吖啶黄高灵敏离子缔合分光光度法测定痕量镉

以聚乙烯醇为表面活性剂,在pH3.6乙酸-乙酸钠缓冲介质中,吖啶黄与[cdI4]2-络阴离子形成稳定的离子缔合物[AY]2[CdI4].该缔合物的最大吸收波长为294nm,表观摩尔吸光系数为3.0×105L·mol-1·cm-1,Cd(Ⅱ)质量浓度在0-25μg· L-1范围内符合比耳定律.该法直接用于铜镉渣中镉的测定,选择性好、灵敏度高,相对标准偏差为4.5％,测定结果令人满意.     

阻抑动力学分光光度法测定痕量镉

基于在盐酸介质中,镉(Ⅱ)对溴酸钾氧化甲基蓝褪色反应有显著的阻抑作用,建立了测定痕量镉(Ⅱ)的动力学方法.以604nm为测定波长,镉(Ⅱ)在0.01-1.7μg·mL-1内呈线性关系,检出限为5.6×10-3μg·mL-1.测定了动力学参数,该阻抑反应为一级反应,表观反应速率常数为1.58×10-3s-1,活化能为67.89kJ·mol-1.方法用于环境水样中痕量镉(Ⅱ)的测定,相对标准偏差为4.35％,回收率为96.1％-99.0％.     

1-(4-安替比林)-3-(8-喹啉)-三氮烯的合成及其分析应用

报道了新试剂1-(4-安替比林)-3-(8-喹啉)-三氮烯(APQT)的合成及其与镉(Ⅱ)的显色反应研究.在Triton X-100存在下,pH 10.5的Na2B4O7-NaOH的缓冲溶液中,试剂与镉(Ⅱ)形成2:1型的橙红色络合物,最大吸收波长为525nm,表观摩尔吸光系数为2.25×105L·mol-1·cm-1,镉含量在0-15μg/25mL范围内遵守比耳定律.     

基于激光诱导击穿光谱的基体效应

为分析和改善激光诱导击穿光谱技术(LIBS)在定量分析土壤和大米中镉(Cd)元素含量时基体效应对分析结果的影响，以Cd Ⅱ226.502 nm谱线为分析对象，对比研究了基体种类、KCl质量分数和激发方式等对Cd Ⅱ226.502 nm谱线强度和定量分析结果的影响规律。研究结果表明：基体主成分的化学形态和电离能是产生基体效应的主要因素，KCl作为添加剂能明显改善大米中Cd Ⅱ226.502 nm的谱线强度，光电双脉冲激发能显著增强基体中Cd Ⅱ226.502 nm的谱线强度、稳定性并提高信噪比。与单激光脉冲激发方式相比，在光电双脉冲激发下，SiO₂、土壤和大米三种基体中Cd Ⅱ226.502 nm的检测下限分别从372、 332和2 874 mg·kg^-1降低到42、72和37 mg·kg^-1。     

电感耦合等离子体-原子发射光谱法测定CPU导热硅脂中的铅和镉

采用几种消解方法对样品进行前处理,建立了电感耦合等离子体-原子发射光谱法(ICP-AES)同时测定导热硅脂中铅、镉等有害金属元素的方法.结果表明:高温灰化法Pb、Cd有损失;(1 1)王水湿法消解法Pb有损失;硝酸-高氯酸湿法消解法Pb和Cd几乎无损失;该方法精密度范围为0.22%-2.40%,Pb和Cd检出限分别为0.030μg·mL-1和0.006μg·mL-1.与石墨炉原子吸收光谱法(GFAAS)相比,ICP-AES具有简单、快速、准确等特点.     

Mn(Ⅱ)-5-Br-PADAP共沉淀-火焰原子吸收光谱法测定虾、贝样中的镉

提出了一种测量痕量重金属镉的新方法。该方法创新性地以Mn(Ⅱ)作为载体离子,以2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚(5-Br-PADAP)作为共沉淀剂,共沉淀分离富集虾、贝样品中的镉,同时采用火焰原子吸收法进行测定。重点探讨了共沉淀剂加入量、载体离子加入量、pH值、共沉淀时间、共存离子的干扰等因素对共沉淀分离富集效果的影响, 从而确定了Mn(Ⅱ)-5-Br-PADAP共沉淀分离富集测定镉的最佳共沉淀条件。实验结果表明,当pH 7且大量干扰离子存在的条件下,Mn(Ⅱ)-5-Br-PADAP体系对镉有良好的共沉淀分离富集效果,很好地克服了基体干扰。共沉淀体系中镉含量在0.1～1.0 mg·L-1范围内时镉含量与吸光度呈线性关系。该方法的灵敏度为0.147(mg·L-1)-1,精密度为0.73%,对镉的检出限(3σ)为4.27 μg ·L-1。食品样品比较复杂,对其中痕量重金属含量的测定必须经过消化、分离富集等一系列预处理过程才能得到最准确地答案。所以通过对比直接用火焰原子吸收法与应用本方法测定样品中镉含量的区别,进一步说明了Mn(Ⅱ)-5-Br-PADAP体系对样品中重金属镉有很好的分离富集效果。根据该方法,采用标准加入法测得干贝样品中镉的含量为1.85 mg·kg-1,干虾样品中镉的含量为1.74 mg·kg-1,基本符合国际食品法典委员会的标准。为了证明该方法的可靠性与真实性,做了加标回收实验,结果显示干虾干贝样品中镉的加标回收率范围为99.9%～100.3%,相对标准偏差为0.15%～0.83%。用Mn(Ⅱ)-5-Br-PADAP共沉淀分离富集样品中的痕量镉具有重现性好、准确度高、简单快速等的优点,分析结果令人满意。     

邻羧基苯基重氮氨基偶氮苯光度分析法同时测定汞与镉

在pH=10.6的硼砂-氢氧化钠缓冲溶液和Triton X-100存在下,汞与镉同时与邻羧基苯基重氮氨基偶氮苯发生灵敏的显色反应,生成红色配合物,其最大吸收波长均为520nm,在0.02-0.6μg/mL浓度范围,汞或镉符合比耳定律,表观摩尔吸光系数分别为εHg=1.75×105L·mol-1·cm-1和εCd=1.89×105L·mol-1·cm-1.两者相互干扰严重,采用焦磷酸钠作为镉的掩蔽剂,成功实现了汞和镉的分别检测和同时定量.本方法中汞的检出限为0.01μg/mL,镉的检出限为0.005μg/mL.应用于加标水样的实际测定,结果令人满意.     

新三氮烯显色剂合成及对镉的显色性能研究

报道了一种新的显色剂(4-氟-4′-偶氮苯基重氮氨基偶氮苯,简称:FADAB)的合成、性质及其与Cd()的显色反应。在弱碱介质中,Triton X-100存在下该试剂与Cd()形成络合比为4∶1的红色络合物。络合物在最大吸收波长524nm处,线性范围为0—10μg/25mL,最大摩尔吸光系数达到1.79×105L·mol-1·cm-1。有较好的选择性,用于测定环境土壤样中镉含量,结果令人满意。     

光谱法分析晶须表面离子印迹对镉的吸附行为

以Cd(Ⅱ)离子为模板分子,壳聚糖为功能单体,3-缩水甘油醚氧丙基三甲氧基硅烷(KH-560)作为交联剂同时加入一定量的三钛酸钠晶须合成了新型的三钛酸钠晶须表面Cd(Ⅱ) 离子印迹聚合物吸附剂,通过电感耦合等离子体原子发射光谱法(ICP-AES)研究了此离子印迹聚合物对Cd(Ⅱ)的吸附行为; 探讨了酸度、吸附剂用量,静置时间对吸附行为的影响,同时研究了印迹聚合物对Cd(Ⅱ)的吸附动力学和吸附等温线,得出此吸附属Langmuir吸附模型。根据吸附效率系数(K_d)和选择性系数(K)的大小,考察了离子印迹聚合物的吸附选择性。试验结果表明：在最佳优化条件下,离子印迹聚合物对Cd(Ⅱ)的吸附率可达99%以上,最大吸附容量为52.34 mg·g-1,选择性优于空白印迹聚合物,此方法的检出限为0.024 μg·mL-1,相对标准偏差为1.74%(c=1.0 μg·mL-1, n=13)说明此离子印迹聚合物适用于环境中水样的Cd(Ⅱ)的选择性吸附。     

ICP-AES法研究六钛酸钾晶须对Cu(Ⅱ),Pb(Ⅱ),Cd(Ⅱ)的吸附性能

以电感耦合等离子体原子发射光谱法(ICP-AES)为检测手段,研究了新型吸附剂六钛酸钾晶须对环境样品中Cu(Ⅱ),Pb(Ⅱ),CA(Ⅱ)的分离/富集行为以及解脱的主要因素,并考察了共存离子的干扰影响.在pH值为5.0,振荡时间为5 min,静置时间为30 min时,吸附率可达到95%以上.以3 mol·L-1HNO3作为解脱剂,沸水浴加热40 min,振荡5 win.静置40 win,可将吸附在六钛酸钾晶须上的Cu(Ⅱ),Pb(Ⅱ),Cd(Ⅱ)定量洗脱.测定Cu(Ⅱ),Pb(Ⅱ),Cd(Ⅱ)的检出险分别为0.007 1,0.006 8,0.007 1 μg·mL-1,相对标准偏差(RSD)为0.63%,0.61%,0.50%.在优化的实验条件下,将其用于菊花和琵琶叶中Cu(Ⅱ),Pb(Ⅱ),Cd(Ⅱ)含量的测定,加标回收率在900A～102.9%之间.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.