氢化物发生-原子荧光光谱法测定食盐中Pb

盐酸处理食盐试样 ,氢化物发生 -原子荧光光谱法直接测定食盐中铅含量 ,试验了不同的酸及酸度对测定的影响。方法的检出限为 9.92 ng/ g,回收率为 95 .1 %— 1 0 5 .3% ,相对标准偏差为 4 .1 4 %。方法操作简便、快速 ,适用于食盐中铅的测定     

氢化物发生-原子荧光光谱法测定酱油中的铅

采用硝酸-高氯酸消解,氢化物发生-原子荧光光谱法测定酱油中铅,线性检测范围:0-200ng/mL,方法检出限:0.0991ng/mL,加标回收率:94.347%-98.033%.     

氢化物发生-原子荧光光谱法测定豌豆中的硒

以HNO3-HClO4消解样品,用HCl将六价硒还原为四价硒,建立了氢化物发生-原子荧光光谱法测定豌豆中硒的方法.在选定的最佳实验条件下,方法的检出限为0.1 ng/mL,线性范围为0-80 ng/mL.应用于三种豌豆中硒的测定,回收率为90.5%-110.6%,RSD为2.0%-5.7%.     

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.     

氢化物发生-原子荧光光谱法测定化妆品中的铅

本文介绍了氢化物发生－原子荧光光谱法对化妆品中铅含量的定量分析方法,并研究拟定了原子荧光光谱法测定铅的分析条件,本方法回收率为96.0%－101.5%,检出限为0.18ng/mL,精密度（RSD）为0.90%-0.94%,准确性好,可用于测定化妆品中铅的含量。     

氢化物发生-原子荧光光谱法测定肥料中微量砷

研究了氢化物发生-原子荧光光谱法测定肥料中的微量砷,优化了最佳检测条件,对肥料样品采用了不同的前处理方法进行了探讨.检出限为0.028mg/kg,线性范围0-100.0μg/L,回收率为95%-100%.该方法操作简便,灵敏度高,准确度好.该法参加了2003年全国肥料中砷的测定能力验证,取得了令人满意的结果.     

氢化物原子荧光光谱法测定茶叶中的硒

采用氢化物发生原子荧光光谱法对多种滇产绿茶中硒的含量进行了分析,建立了仪器及氢化物产生的最佳实验条件,方法的线性回归方程为I=122.05C 15.295,相关系数r=0.9999,线性范围为0.18-30μg/L.最低检出限为0.055μg/L.测定结果表明,茶叶中硒的回收率在93%-102%之间.     

氢化物发生-原子荧光法测定饮料中砷含量的不确定度评定

本文以氢化物发生-原子荧光光谱法测定饮料中砷含量为实例,建立了数学模型,对测试过程中不确定度的各个分量进行了分步计算及合成,计算出扩展不确定度为0.0011mg/L.结果表明校准曲线是氢化物原子荧光法测定饮料中砷含量不确定度的主要影响因素.     

氢化物发生-原子荧光光谱法测定土壤中的汞

研究了氢化物发生 -原子荧光光谱法测定土壤中的总汞 ,在最佳条件下 ,荧光强度与汞浓度在 0—10μg· L-1范围内呈线性关系 ,相关系数为 0 .9997,检出限为 0 .0 4μg· L-1。方法的回收率为 94 .6 %—10 4 .3% ,相对标准偏差不超过 7.2 %。方法具有操作简便、快速、灵敏度高等优点。     

微波消解-氢化物发生-原子荧光光谱法测定7种中草药中砷

利用原子荧光光谱法测定7种驱虫类中草药中的砷.实验采用微波消解样品,以盐酸为测定介质,硫脲-抗坏血酸为预还原剂,硼氢化钾为氢化剂,用氢化物发生-原子荧光光谱法测定砷含量.砷含量在10-100ng/mL浓度范围内线性关系好(r2=0.9924).回收率为93.83%-110.94%之间.方法简便、快速、灵敏、准确,可用于中草药中砷的测定.     

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.