标准加入法在能力验证考核酱油铅含量中的应用

采用标准加入法-硝酸钯基体改进剂消除酱油中食盐的机体干扰,建立了标准加入法-硝酸钯基体改进剂GFAAS测定酱油中痕量铅的方法,该方法的检出限为4.2μg/L,精密度为1.52%—4.96%,在5、20μg/L添加水平回收率为91.6%—108.2%,90.5%—101.7%,方法简单、快速、检出限符合标准分析要求。     

双道原子荧光光谱法同时测定土壤中的砷和汞

建立了同时测定土壤中砷和汞的原子荧光光谱法。样品的相对标准偏差 As为 3.94 % ,Hg为 5 .0 0 % ,回收率在 90 %— 93%之间 ,对砷、汞的检出限分别为 0 .18μg/L和 0 .0 5 7μg/L。本法操作简便、快速、灵敏度高。     

湿法消解-氢化物发生-原子荧光光谱法测定土壤中的铅

应用AFS-230E型双道原子荧光光谱仪进行了氢化物发生-原子荧光法测定土壤中铅的研究.方法中采用硝酸做介质,将铁氰化钾直接加入硼氢化钠-氢氧化钠碱性溶液中,并对各种最佳分析条件进行了探讨和验证.铅的校准曲线在0-100μg/L浓度范围内呈线性,方法的检出限为0.14μg/L,相对标准偏差为2.1％,回收率为91.0％-95.0％.用标准物质进行对照,其测定值在给定的标准值范围之内.该方法操作简单、灵敏度高、高效,适合土壤样品中铅的测定.     

分散液液微萃取-分光光度法测定环境水样中孔雀石绿

建立了简便、快速、有效的分散液液微萃取-分光光度法测定环境水样中孔雀石绿的分析方法。对萃取剂、分散剂的种类和体积、萃取时间、离心时间、盐浓度等影响萃取效率的因素进行了优化。在优化的萃取条件下,方法的线性范围为8—1000μg/L（r=0.9992）,相对标准偏差（RSD）为4.1%（C=100μg/L,n=6）,检出限为4.20μg/L。对3种实际水样中的孔雀石绿进行测定,加标回收率在74.7%—108.2%之间（n=5）。方法适用于环境水样中的痕量孔雀石绿的检测。     

不同酸介质测定烟草中微量铅

采用硝酸-高氯酸混合酸消解样品,盐酸为介质,氢化物发生-原子荧光光谱法(HG-AFS)检测铅,对不同酸介质的浓度、样品前处理和不同烟草样品进行试验,测定香料烟、白肋烟、杀青烟、烟梗平行样品中Pb,其相对标准偏差为0.53%—4.39%;方法的检出限为0.1506μg/L;检测的线性范围为0—80.0μg/L;加标回收率为85.6%—96.9%;用茶叶标准GBW 08513和GBW 07605进行验证,测定结果与标准值相吻合。     

氢化物发生-原子荧光光谱法测定恩施富硒土壤中的总硒

采用氢化物发生-原子荧光光谱法测定恩施富硒土壤中的总硒,优化了各项实验条件,确定了最佳方法。在最佳实验条件下,方法的检出限为0.04μg/L,线性范围为0.12—80μg/L,RSD为0.87%。测得样品含量在3.449—115.070μg/g之间,回收率为97.8%—101.1%,方法简单、结果准确、重现性好,适合测定富硒土壤中的总硒含量。     

不同产地几种中药材中重金属含量测定及砷的形态分析

通过对不同产地几种中药材中砷、铅、镉、铜以及无机砷、三价砷含量的分析测定,得出样品中砷、铅、镉、铜以及无机砷、无机三价砷的测定RSD〈3%,加标回收率在91.32%—109.7%之间。11个样品的总砷含量在0.047—1.681μg/g之间,均低于2μg/g;无机砷含量为0.023—1.294μg/g;无机三价砷含量为0.019—0.918μg/g;铅含量两份样品未检出,其余样品为0.007—0.786μg/g,均低于5μg/g;镉的测定,两份样品未检出,其余样品含量为0.007—2.129μg/g,其中两份样品大于0.3μg/g;铜含量为4.441—14.07μg/g,均低于20μg/g。研究发现同种药材不同产地的重金属含量差异较大,部分产地金银花中镉含量超标严重,无机砷和三价砷含量相对较高,需引起重视。     

牡丹皮及种植土壤中重金属元素铅和镉的分析

测定不同产地牡丹皮及种植土壤中的重金属铅、镉含量,并分析牡丹皮与种植土壤中铅、镉含量的相关性.从安徽和山东产地采样,通过硝酸-过氧化氢-氢氟酸体系进行牡丹皮和种植土壤微波消解,用石墨炉原子吸收光谱法(GFAAS)测定牡丹皮和种植土壤中铅、镉含量.Pb元素在0-60μg/L范围内线性关系良好,回收率为102.35％,精密度RSD为1.6％ ;Cd元素在0-4μg/L范围内线性关系良好,回收率为99.85％,精密度RSD为0.7％.不同产地牡丹皮均检出重金属元素铅和镉,铅含量偏低、镉含量偏高;种植土壤中的铅、镉含量比较高,大约是牡丹皮的6-7倍.该方法具有分析速度快、测定结果的精确度和精密度高等特点.种植土壤存在着重金属污染现象,为确保药材质量,保护环境、保护药材种植土壤是非常必要的.     

流动注射-氢化物发生-气相化学发光法测定环境样品中的总砷

采用流动注射-氢化物发生-气相化学发光法,建立了一种快速简便测定环境样品中微量砷的新方法。土壤样品、地表水样经消解后,加入抗坏血酸和硫脲,将5价砷还原为3价后,以0.6mol/L硫酸为载液,与1.5%硼氢化钠反应,生成的胂化氢由气液分离器分离后,在反应室里与臭氧反应,产生的化学发光信号由光电倍增管检测。该法线性范围宽(1—500μg/L),检出限为0.15μg/L,相对标准偏差为0.77%(20μg/L,n=11),采样速度为50样/h。应用于环境样品中总砷的测定,结果与氢化物发生原子吸收法一致。     

氢化物原子荧光光谱法测定水产品中的痕量汞

本文研究和确定了氢化物原子荧光光谱法检测水产品中汞的适宜检测条件，建立了V2O5－HNO3－H2O2消解体系，并以硫脲作为掩蔽剂，低浓度硼氢化钾为还原剂。本方法线性范围为0－80μg/L；相关系数r≥0．9997；检出限为0．005μg/L；相对标准偏差为0．89％－2．64％；回收率为95．7％－104．3％，可广泛用于水产品中汞的检测。     

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.