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.     

反相高效液相色谱法测定1-(4-硝基苯)-3-(5-溴-2-吡啶)-三氮烯

ZORBAX Eclipse XDB- C8(4.6× 1 5 0 mm,5 μm)色谱柱 ,乙腈流动相 ,流速 0 .6 0 m L/min,检测波长4 2 0 nm,反相高效液相色谱法测定 1 - (4-硝基苯 ) - 3- (5 -溴 - 2 -吡啶 ) -三氮烯。该法的线性范围为 1—1 0 .0 μg/m L,线性回归方程为 A=5 .91 5 4 .4 37C,相关系数 0 .9989,相对标准偏差为 0 .8973%(C=7.2 0 μg/m L,n=5 ) ,检出限为 0 .0 2 872 μg/m L,平均回收率在 93.2 %— 1 0 2 .2 %之间。     

鱿鱼丝中乳糖含量的测定

以苯酚、氢氧化钠、苦味酸和亚硫酸氢钠混合溶液为显色剂 ,分光光度法测定鱿鱼丝中乳糖含量。乳糖在 4— 80 μg/m L范围内与吸光度呈良好的线性关系 ,检出限为 1 .0 μg/m L,回收率为 99.8%— 1 0 0 .0 %。该法简便快捷 ,结果令人满意     

双硫腙浊点萃取-石墨炉原子吸收光谱法测定环境水样中痕量铅的研究

基于表面活性剂的浊点现象,建立了以双硫腙为螯合剂、Triton X-114为表面活性剂的浊点萃取-石墨炉原子吸收光谱法测定痕量铅的新方法。研究了溶液pH值、试剂浓度、平衡温度和加热时间等实验条件对浊点萃取及测定灵敏度的影响。以4 000 r·min-1离心15 min使分相, 分相后的溶液在冰水浴中冷却至接近0 ℃,然后反转离心管弃去水相,用0.1 mol·L-1 HNO₃-甲醇溶液定容至0.5 mL, 溶液以磷酸二氢铵及硝酸镁为基体改进剂由石墨炉原子吸收分光光度法进行测定。在pH 8.0和0.05% Triton X-114及20 μmol·L-1双硫腙存在下, 富集10 mL样品溶液,铅的检出限为0.089 μg·L-1,富集倍率为19.1,所得工作曲线回归方程为A=0.0261c(μg·L-1)+0.010 6,线性范围0.1～30 μg·L-1,相关系数r为0.998。方法用于环境水样中测定痕量铅的测定,获得满意结果。     

氢化物发生-原子荧光光谱法测定贻贝中的砷

以 HNO3 - H2 SO4消解样品 ,氢化物发生原子荧光光谱法测定了贻贝中的砷。研究了消化方法、介质及酸度、还原剂浓度、硫脲 -抗坏血酸用量、干扰离子等对测定的影响。在最佳试验条件下 ,荧光强度与砷浓度在 0 .174 5— 2 0 0 .0 μg/L范围内呈线性关系 ,相关系数 r为 0 .9990 ,检出限为 0 .0 349μg/L。标准样品的推荐值和 ICP- AES分析结果相符。方法简便、快速、灵敏、准确。     

索氏提取-氢化物发生-原子荧光法测定中草药中总硒和硒(Ⅳ)

研究了在酒石酸介质中氢化物发生 -原子荧光法测定中草药中的痕量硒的方法和条件 ,结合索氏提取技术 ,分析了 4种中草药中的总硒和硒 ( )。在最佳分析条件下 ,方法检出限为 0 .0 15 μg/L,RSD(n=5 )为 2 .6 %— 3.9% ,加标回收率为 95 .0 %— 10 2 .6 %。     

氢化物发生-原子荧光光谱法测定螺旋藻中的铅

研究了氢化物发生-原子荧光光谱法测定螺旋藻中Pb的适宜条件,分析了酸度、硼氢化钾和基体改进剂浓度、载气流量、灯电流以及原子化器高度等对测定的影响,优选了测定条件.结果表明,铅发生氢化物反应条件为酸性介质,1.5％的盐酸作载流,硼氢化钾还原剂浓度为20g/L,载气流量为500mL/min,空心阴极灯灯电流为60mA,原子化器高度为10mm,此时荧光值强度较大且稳定.最佳测定条件下,其线性范围为0-100ng/mL,相关系数0.9994,仪器检出限为0.383μg/L,相对标准偏差为1.39％,回收率为88.9％-95.9％.用标准物质进行对照,其测定值在给定的标准值不确定度范围之内.对螺旋藻中铅的测定,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海水中的痕量锡

对氢化物发生-原子荧光光谱仪的仪器条件和氢化反应条件进行了研究,建立了测定海水中痕量锡的方法,方法检出限为0.012μg/L,线性范围0.012-20 μg/L,精密度为5.5%.     

微波灰化-氢化物发生原子荧光光谱法测定植物油中微量铅

采用微波灰化技术处理样品 ,运用断续流动 氢化物发生原子荧光光谱法测定植物油中的铅 ,探讨了微波灰化条件对铅测定的影响 ;研究了载流和样品酸度、还原剂浓度、基体改进剂以及载流流速对氢化物发生的影响。铅的线性范围为 1 0 0～ 2 0 0 μg·L-1,最低检出限为 0 31μg·L-1,相对标准偏差为 1 84 % ,回收率为 89 2 %～ 97 3%。     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.