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。     

原子荧光光谱法测定中药中的汞

采用原子荧光光谱法测定了中药中汞，考察并优化了影响汞原子荧光强度的实验条件；提出硫脲-柠檬酸-Fe^3 作为增感剂以增强汞的荧光信号；探讨了共存离子对汞测定的干扰及其消除方法。在最佳工作条件下，方法的检出限为5．748μg／L；相对标准偏差为1．56％；线性范围为0—1000μg／L。用于6种中药样品中汞的测定，回收率为90．4％-109．6％。     

HG-AFS同时测定锌锭中的砷和汞

采用盐酸分解样品,用聚环氧琥珀酸(PESA)掩蔽基体,建立了氢化物发生-原子荧光光谱法(HG-AFS)测定锌锭中砷和汞的方法.实验表明,0.1g锌锭溶解后加入2.0mL PESA可以有效地掩蔽基体元素Zn,共存元素Mg、Al、Cu、Sb和Sn不干扰As和Hg的测定.砷和汞的方法检出限分别为0.26μg/L和0.043μg/L.将方法应用于实际样品分析,砷和汞的相对标准偏差(RSD,n=5)分别在1.1％-2.0％和1.0％-1.6％之间.加标回收率分别为96.1％-120.0％和92.8％-108.8％.     

顺序注射氢化物发生-原子荧光光谱法测定化肥中砷、汞、锑和硒

本文建立了一种顺序注射氢化物发生 -原子荧光光谱法测定化肥中 As、Hg、Sb、Se含量的方法。在最佳条件下 ,As、Hg、Sb和 Se的检出限分别为 0 .1 5μg/ L、0 .0 6 1μg/ L、0 .0 4 6μg/ L、0 .2 5μg/ L。测定化肥中 As、Hg、Sb和 Se,回收率均在 94 .6 7%— 1 0 6 .81 %之间。该方法用于检测化肥中 As、Hg、Sb和 Se具有很好的可行性和实用性。     

氢化物发生-原子荧光光谱法同时测定纺织品中痕量砷和汞

本文以模拟汗液 (酸性、碱性 )和唾液萃取样品 ,断续流动 -无色散氢化物发生原子荧光光谱法同时测定纺织品中的微量砷、汞。研究了不同萃取介质、酸度、还原剂浓度、共存元素以及载流流速对氢化物发生的影响。方法快速、基体干扰少、灵敏度高、检出限低。本方法的线性范围为 As:1.0 0— 2 0 0 μg· L-1,Hg:0 .5 0— 2 0 μg· L-1,检出限为分别为 0 .0 3μg· L-1和 0 .0 1μg· L-1,回收率为 89.4 %— 10 0 .5 % ,精密度为 1.32 %— 5 .4 5 %。     

HG-AFS同时测定驱蚊水中的砷和汞

采用氢化物发生-原子荧光光谱法测定驱蚊水中的砷(A s)和汞(Hg)。在0—50.0μg/L范围内砷和汞的浓度与荧光强度呈线性关系,相关系数均为0.9993,加标回收率分别达到99.76%—103.46%和90.10%—100.10%,砷、汞测定结果的RSD分别小于3.9%和6.6%;同时指出了测定时应注意的事项。     

断续流动-氢化物发生原子荧光光谱法测定硫磺中的微量砷

采用断续流动-无色散氢化物发生原子荧光光谱法测定硫磺样品中的微量砷含量。采用一系列单一变量优化了酸度、还原剂浓度、共存元素以及载流流速对氢化物发生的影响,本方法快速简单、灵敏度高、检出限低。检测线性范围为1．0—100μg/L,检出限为为0．519μg／L,回收率为91．4％-99．2％。     

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。     

铟(Ⅲ)-8-羟基喹啉-核酸三元荧光体系的研究与应用

基于核酸对铟(Ⅲ）-8-羟基喹啉配合物的荧光增强作用，应用铟(Ⅲ)-8-羟基喹啉为荧光探针，研究了铟(Ⅲ)-8-羟基喹啉与核酸的作用，建立了新的核酸测定方法。在最佳条件下，ctDNA、hsDNA、smDNA和yRNA的线性范围分别为0．20-1．40μg／mL、0．20-1．60μg／mL、0．10—1．40μg／mL、0．20—1．20μg／mL。检出限(3o／K)分别为0．004μg／mL，0．002μg／mL，0．002μg／mL，0．002μg／mL；测定实际样品，回收率为90．9％-103．5％。     

氢化物发生-原子荧光法测定中药中痕量砷

采用HNO3—HCIO4体系消解中药样品，优化实验条件，建立了氢化物发生-原子荧光法测定中药中痕量砷的方法。砷的相关系数为0．9993，检出限为0．36μg／L，茶叶(GBW08505)验证结果与推荐值一致，相对标准偏差为0．89％。该方法灵敏、简便、快速、准确，对于实际样品的测定得到了满意的结果。     

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.