罗丹明B氧化褪色光度法测定微量碘

本文研究了在硫酸介质中 ,碘酸根在 KBr催化作用下氧化罗丹明 B使其褪色的最佳条件 ,建立了测定微量碘的新方法。通过实验 ,测得最大吸收波长为 4 90 nm ;表观摩尔吸光系数为 1 .5× 1 0 4 L· mol-1· cm-1;碘酸根测定的线性范围为 0— 3 0μg/1 0 m L;检出限为 1 .2× 1 0 -7mol/L。该方法可用于食盐中微量碘的测定     

甲酚红氧化褪色光度法测定微量碘

本文研究了在硫酸介质中 ,碘酸根在 KBr催化作用下氧化甲酚红使其褪色的最佳条件 ,建立了测定微量碘的新方法。最大吸收波长为 5 19.5 nm,表观摩尔吸光系数为 4 .6× 10 4L· mol-1· cm-1,碘酸根测定线性范围为 10— 6 0 μg/2 5 m L。用于测定食盐和碘酸钾片剂中微量碘 ,结果令人满意     

碘蓝分光光度法测定微量铬（Ⅳ）

基于在酸性介质中 ,重铬酸钾与碘化钾、淀粉的显色反应 ,建立了碘蓝分光光度法测定微量铬 ( )的方法。铬 ( )浓度在 0— 0 .6μg/ m L范围内有良好的线性关系 ,方法的相对标准偏差为 1.3% ,表观摩尔吸光系数为 5 .6 3× 10 4 L· mol- 1 · cm- 1 ,检出限为 2 .0× 10 - 3μg/ m L     

停流流动注射-化学发光法测定碘盐中的碘酸根

基于在酸性介质中 ,IO-3 与 I-快速反应产生 I2 ,I2 氧化 Luminol产生化学发光反应的机理 ,建立了Luminol- IO-3 偶合发光体系测定微量 IO-3 的方法。本法测定 IO-3 的线性范围为 5 .0× 10 -8- 3.0× 10 -5g/m L;检出限为 5 .0× 10 -8g/m L ;该法中的采样、停流和进样都由计算机自动控制 ,操作简便 ,灵敏度高 ,选择性好。应用于含碘食盐中微量 IO-3 的测定 ,结果令人满意     

偶氮胂Ⅲ褪色分光光度法测定食盐中碘

在硝酸介质中 ,有溴化钾存在下 ,碘酸根对偶氮胂 有褪色作用 ,且褪色的程度与碘酸根的量在一定范围内呈正比。据此建立了测定微量碘的新方法。最大吸收在 5 33nm处 ,碘浓度在 0— 8.0 μg/ 10 m L 范围内符合比耳定律 ,检出限为 8.38× 10 - 9g/ m L,方法操作简单 ,重现性好 ,用于加碘食盐中碘的测定 ,结果令人满意     

2′,7′-二氯荧光素荧光光谱法测定饲料中微量总砷

在 p H=7.5缓冲溶液中 ,I2 与 2′,7′-二氯荧光素反应 ,引起荧光猝灭 ,加入 As3 与 I2 反应 ,体系荧光增强 ,基此建立了荧光光谱法间接测定微量As3 的新方法。荧光发射波长为 λem=5 2 0 nm。砷含量在 1 0— 1 0 0 .0 μg/L范围内呈现良好的线性关系 ,回归方程为 ΔIF=0 .4 92 0 0 .70 0 5 C(C:μg/L) ,相关系数 r=0 .9980 ;检出限为 1 .0 μg/L。本法用于饲料样品中微量总砷的测定 ,获得满意的结果。     

氢化物发生-原子荧光光谱法测定铁矿石中微量锡

以氢氧化钾熔矿 ,硫酸酸化样品 ,硼氢化钾作还原剂 ,建立了氢化物发生 -原子荧光光谱法测定铁矿石中微量锡的新方法。检出限为L D(Sn) =0 .1 0 μg/ L,回收率在 96 .2 %— 1 0 3%,RSD为 0 .90 %(n=1 2 )。该法检出限低 ,灵敏度高 ,测定结果准确可靠 ;操作简单、快速等特点 ,完全满足铁矿石中微量锡的测定。     

碘蓝分光光度法测定微量铬(Ⅵ)

基于在酸性介质中,重铬酸钾与碘化钾、淀粉的显色反应,建立了碘蓝分光光度法测定微量铬(Ⅵ)的方法.铬(Ⅵ)浓度在0-0.6μg/mL范围内有良好的线性关系,方法的相对标准偏差为1.3%,表观摩尔吸光系数为5.63×104L·mol-1·cm-1,检出限为2.0×10-3μg/mL.     

以十二烷基苯磺酸钠为增溶剂阻抑催化光度法测定痕量碘

在 p H=4 .5的 HAc- Na Ac介质中 ,痕量碘能阻抑以 2 ,2′-联吡啶为活化剂 ,阴离子表面活性剂十二烷基苯磺酸钠 (SDBS)为增溶剂 ,银催化过硫酸钾氧化天青 ( )的褪色反应 ,据此建立了测定痕量碘的阻抑催化动力学光度分析新方法。本法检出限为 3.6× 10 -3 mg/ L ;线性范围为 0 .0 2— 0 .16 mg/ L。用于紫菜、海带中痕量碘测定 ,结果满意     

催化动力学光度法测定乙醛催化剂中的微量钯

基于 p H 5 .5 0的乙酸 -乙酸钠介质中 Pd( )催化次磷酸钠还原结晶紫的褪色反应 ,建立了测定微量钯的催化动力学光度法 ,研究了最佳反应条件和动力学参数。方法的检出限为 4 .7× 1 0 -9g Pd( ) /m L,线性范围为 0— 0 .8μg/2 5 m L,表观摩尔吸光系数为 7.6× 1 0 5L· mol-1· cm-1,用于测定乙醛催化剂中的微量钯 ,取得满意结果     

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.     

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.     

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.     

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.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

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.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.     

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.     

Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.     

A novel methodology for photometric compensation of projection display on patterned screen

We propose a novel methodology based on the projector-camera (ProCam) system to address the photometric compensation issue for the projection display on the patterned screen.The patterned screen is treated as the combination of a perfect white screen and a color modulator.The perfect white screen is used to automatically and accurately characterize the ProCam system offline using the polynomial model,and the parameters of the color modulator can be efficiently recovered by employing only two gray images based on the linear reflectance model.The experimental results show that the color artifacts of the display image can be greatly improved with this methodology,which demonstrates its feasibility and validity in the photometric compensation.