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%.     

双道原子荧光光谱法同时测定农产品中的砷和硒

研究了AFS-930型双道原子荧光光度计同时测定农产品中砷和硒的方法.该法快速,简便,准确,砷回收率为91.9%-99.6%,硒回收率为93.5%-103.8%,相对标准偏差(RSD)砷小于2%,硒小于1%,检出限分别为0.035μg/L和0.038μg/L.     

微波高压消解双道原子荧光法测定蔬菜总砷和汞

用微波高压消解技术处理样品,用原子荧光光谱仪测定蔬菜中总砷汞,具有快速、方法简便、结果准确可靠的优点.方法的回收率为:砷90.1%-106.9%,汞91.0%-104.0%;检出限为:砷0.10μg/L,汞0.008μg/L.     

微波消解-氢化物原子荧光光谱法测定油菜籽中的砷和汞

用用微波消解法处理富含油脂的油菜籽样品,氢化物原子荧光光谱法（HG-AFS）测定其中的砷和汞。砷在1—16μg/L范围内,有良好的相关性,相关系数r=0.9992;汞在0.1—1.6μg/L范围内,有良好的相关性,相关系数r=0.9994;砷和汞检出限分别为3.0μg/kg和1.6μg/kg;砷和汞测定的相对标准偏差RSD分别为9.8%、10%。用标准物质桃叶（GBW08501）验证方法准确性,结果令人满意。     

氢化物-原子荧光光谱法测定金属饰品中的砷和汞

采用氢化物-原子荧光光谱法测定金属饰品中砷和汞.用体积比为3:1的浓硝酸和浓盐酸微波消解样品.结果表明:砷和汞方法的检出限分别为0.079μg/L和0.037μg/L;砷、汞RSD分别为1.89%和4.82%;砷的加标回收率为99.6%,汞的加标回收率为96.0%.该方法快速简便,能满足饰品的日用检验要求.     

微波消解-氢化物发生原子荧光法测定重油中的砷和汞

采用微波消解处理样品,以硫脲为预还原剂硼氢化钾为还原剂,氢化物发生原子荧光法测定重油中的砷和汞。采用微波消解方法进行样品处理,其结果表明,方法具有高效快速、试剂消耗量少、节能、环保等优点。考察了预还原剂硫脲和抗坏血酸对测定结果的影响。考察了酸度、还原剂浓度、基体效应、光电倍增管负高压、原子化器高度、灯电流和载气流量的影响,优化操作条件。测定砷和汞的线性范围分别为2~12μg/L和0.2~1.2μg/L,线性回归方程为If=a*c+b(c:μg/L),相关系数分别为0.9998和0.9981,砷和汞的检出限分别为0.009μg/L和0.007μg/L,对7个样品进行回收实验,砷、汞的回收率分别为90%~109%、92%~105%准确度较高;11次测定的标准偏差小于5%,精密度较好。本方法用于重油中砷和汞分析,可满足科研和生产需要。     

微波消解-氢化物原子荧光光谱法测定食品中的微量元素硒

采用HNO3-HClO4作为消解剂,在微波消解炉中消解样品,原子荧光光谱法测定食品中的微量元素硒.在最佳测定条件下测定元素硒的线性回归方程为:IF=95.4853C 9.2045,线性范围为0.5-10.0μg/L,相关系数r=0.9997.回收率2.0μg/L为95.65%-103.04%,6.0μg/L为95.61%-102.42%;相对标准偏差2.0μg/L为2.18%-3.55%,6.0μg/L为2.22%-3.98%.食品样品采用微波消解后,可用氢化物原子荧光光谱法测定其中的微量元素硒.     

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。     

双道原子荧光光谱法同时测定农产品中的砷和汞

研究了湿法消解,双道原子荧光光度计同时测定农产品中的砷和汞,优化了检测条件和消解步骤,为在日常工作中,检测大量样品提供了快捷、简单、准确、灵敏和重现性好的方法。砷、汞检出限分别为:0.053μg/L、0.0136μg/L。针对一般化验室的仪器配置,采用简便的湿化消解方法,样品砷和汞加标回收率分别为96.8%—101.2%和96%—97.5%,对国家标准物质茶叶、牛肝等进行检测,精密度和准确度都符合要求。     

流动注射-氢化物发生-ICP-AES测定滇龙胆中的有害元素

使用流动注射-氢化物发生-电感耦合等离子体原子发射光谱(ICP-AES)联用技术同时测定中药滇龙胆中微量有害元素砷、铅、镉和汞的含量。对影响分析信号的主要工作条件进行了选择和优化。砷、铅、镉和汞的检出限分别为0.46、1.41、0.29μg/L和0.31μg/L;其回收率分别为99.0%、105.0%、100.0%和108.0%。本法用于中药滇龙胆中微量有害元素的分析,结果满意。     

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.