小麦粉中痕量砷的测定研究

流动注射 -氢化物发生 - ICP- AES检测小麦粉样品中痕量的砷 ,正交设计试验找出仪器测定的最佳工作条件 ,并对影响测定的主要参数和砷的氢化物产生条件进行了研究。该方法对小麦粉中砷的检测结果令人满意 ,砷检出限为 0 .15 μg/ L,相对标准偏差 <2 .5 %。     

原子荧光光谱法测定饮用水中的砷

研究了两种载流溶液浓度和还原剂溶液浓度条件下,原子荧光光谱法测定饮用水中砷的过程中仪器荧光强度值和光谱峰的变化,对仪器测量条件进行了优化.研究了不同检测条件下,待测水样中砷元素检出量的变化.结果表明,载流溶液浓度影响仪器荧光强度值的大小,还原剂溶液浓度影响光谱峰的出峰位置.盐酸和硫脲-抗坏血酸的加入影响待测水样中砷含量的测定结果.     

光谱法测定黄磷中微量砷的研究

文章对测定黄磷中微量砷的各种光谱分析方法的研究进展作了综述,讨论了黄磷试样的处理方法和条件,重点讨论了Ａｇ－ＤＤＴＣ光度法,新银盐光度法,ＩＣＰ－ＡＥＳ法和原子荧光法在测定黄磷中微量砷的具体应用,对今后测定黄磷中微量砷的新方法的研究方向作一些探讨。     

氢化物发生-原子荧光光谱法测定铜阳极泥中的砷

用氢化物发生-原子荧光光谱法测定铜阳极泥中的砷量,研究了仪器测量条件、氢化物发生条件、共存元素等因素对测定结果的影响.选择了最佳测定条件,砷的测定范围为0.50%-5.00%,加标回收率在98.3%-108.0%之间,相对标准偏差小于4%,能满足测定的要求.     

悬浮进样-氢化物发生-原子吸收光谱法测定化妆品中的微量砷

建立了一种悬浮进样-流动注射-氢化物发生-原子吸收光谱测定化妆品中痕量砷的新方法,实验考察和优化了影响砷信号强度的氢化物发生条件和悬浮条件.以无水乙醇作分散剂,1.5g/L琼脂作稳定剂,得到了满意的分析效果.方法具有操作简易、快速,灵敏度高等特点.     

微波消解-氢化物发生原子荧光光谱法测定土壤中砷和硒

采用王水(1 1)作消解剂,以微波消解的方法处理土壤样品,氢化物发生-原子荧光光谱法测定土壤中砷、硒,设定了最佳的样品处理条件和仪器测定条件.利用加标回收试验,对分析方法进行了验证.砷、硒的检出限分别为0.94μg/L和0.15μg/L,测定土壤中砷、硒的回收率分别为90%-105%、89%-104%,RSD分别为2.2%-4.0%、1.9%-3.1%.     

微波消解-氢化物发生原子荧光光谱法测定复合疏松剂中的砷

建立了测定复合疏松剂中砷的微波消解-氢化物发生原子荧光光谱方法,试验了微波消解复合疏松剂样品的适宜条件,试验了测定中酸介质和还原剂用量对砷信号的影响,通过实验确定了仪器的最佳工作条件,讨论了复合疏松剂中常见元素对测定的干扰情况.本方法中,砷的荧光强度与浓度在0-100μg/L范围内呈线性关系,相关系数为0.9992,方法检出限为0.22μg/L,回收率为89%-115%,方法相对标准偏差小于5%.该方法准确、快速,应用于复合疏松剂中砷的测定,获得满意结果.     

云南出口三七中总砷及无机砷的测定

三七中总砷及无机砷按GB/T5009.11-2003进行了大量的测试。三七试样经湿消解,加入硫脲使五价砷还原为三价砷,再加入硼氢化钾使其还原生成砷化氢,和氩气一起进入石英原子化器中分解为原子态砷,测其荧光强度,得总砷。未经消解的三七试样在6mol/L盐酸和水浴条件下,无机砷以氢化物形式被提取,实现无机砷和有机砷的分离,在2mol/L盐酸条件下测定,同总砷原理。通过对大量测试数据的分析,讨论了其无机砷在总砷中所占含量的百分比及毒性。     

新生态MnO2对水中As(V)去除效果

实验研究了新生态MnO2对As(V)除砷效果及影响因素.在优化的实验条件下(室温,pH值6.5附近,MnO2的投加量为100mg,接触时间2h),新生态MnO2对As(V)的去除率达98%;加入阴离子,与As(V)形成吸附竞争;加入阳离子如Fe3+、Al3+等可改善As(V)的去除率.     

原子荧光光谱法同时测定水中痕量砷和硒

用浓盐酸和5%硫脲-5%抗坏血酸混合试剂处理样品,并以2%硼氢化钾和0.5%氢氧化钾为还原剂,在5%的盐酸介质中用原子荧光光谱法同时测定水中砷和硒.对原子化器的高度、灯电流、负高压等实验条件进行了优化选择,确立了最佳分析条件.砷和硒的检出限分别为As:0.5μg/L,Se:0.1μg/L.     

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.     

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.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.