超声波处理悬浮液直接进样火焰原子吸收光谱法测定土壤中的铅

本文采用超声波处理悬浮液、悬浮液直接进样火焰原子吸收光谱法测定土壤样品中的铅。对样品进行 7次平行测定 ,其结果的 RSD≤ 1 .9% ,回收率在 94 .6 %— 1 0 8%之间。此法快速、方便     

混合酸浸提-火焰原子吸收法测定土壤中的铅

本文主要研究了土壤中微量元素铅的测定条件,采用混合酸在沸水浴中加热浸提后,直接上机测定.最佳测定条件是水浴温度为100℃,浸提时间为120min,混合酸为HNO3+HCl+H2O(1+1+2)该方法具有样品前处理简便,测定快速、准确、空白值低等特点,样品加标回收率为92%-102%,RSD为0.83%-6.38%,并用国家标准物质污染农田土壤标样进行验证,其结果吻合.     

土壤中铅、砷、铬、铜和锌含量的连续快速测定

建立了土壤中铅、砷、铬、铜和锌含量的连续快速测定方法。土壤样品经微波消解,用同一份消解液,分别连续测定土壤中的铅、砷、铬、铜和锌含量,铬、铜和锌采用火焰原子吸收光谱法,铅和砷采用氢化物发生-原子荧光光谱法。采用本方法,对环境土壤标准样品ESS-1黑钙土(GSBZ50011)和ESS-3红壤(GSBZ50013)进行多次测定,检测结果与标样的推荐值吻合。经统计计算,回收率为95.2%—103.6%,精密度RSD均小于7%。本法操作简单快速,光谱测定结果已成功地用于无公害水果和蔬菜生产基地的土壤环境质量评价。     

同一种前处理方法测定烟草中砷、铅和镉

采用同一种前处理方法即硝酸和高氯酸消解处理烟草样品后,氢化物发生-原子荧光光谱法测定烟叶中砷、铅;原子吸收光谱法测定烟叶中镉。样品溶液介质为10%的盐酸,对7个样品平行3次重复实验,其相对标准偏差为砷:0.81%—4.96%、铅:2.82%—5.83%、镉:0.96%—4.60%,砷、铅、镉的检测线性范围分别为:0.0—120.0、0.0—60.Oμg·L^-1和0.0—800.0μg·L^-1,加标回收率:砷在94.5%—96.9%之间、铅在92.7%—101.6%之间、镉在102.2%—110.9%之间。     

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%。     

微波消解-ICP-MS测定土壤样品中的重金属离子

采用微波消解-ICP-MS测定土壤样品中铬、铜、镍、锌、镉、铅,利用国家环境标准样品ESS-1验证了方法的准确度,准确度在100%左右,测定值与标准值吻合,相对偏差小于4%,并比较了两种消化方法对测定结果的影响;优化了ICP/MS工作参数;用多内标法有效的校正了基体干扰.进行东北老工业基地某厂区土壤测试.方法的检出限0.0144-1.0218μg·g-1精密度为0.15%-3.51%,回收率为83.2%-108.9%,为环境土壤样品的分析测试提供了一种可靠、高灵敏分析方法.     

GF-AAS法测定处理污水灌溉土壤中铅最佳基体改进剂的选择及其应用

研究了石墨炉原子吸收法（GF-AAS法）测定一级处理污水灌溉土壤中铅最佳基体改进剂的选择及在最佳改进剂条件下测定污水灌溉土壤中铅的GF-AAS法。试验了磷酸二氢铵, 磷酸铵, 氯化铵, Pd-Mg和磷酸二氢铵+硝酸镁+硝酸铵等基体改进剂对测定一级处理污水灌溉土壤铅的基体改进作用,并根据基体改进剂的改进效果,最佳灰化温度和原子化温度, 选定了最佳基体改进剂和测定条件。40 g·L-1的磷酸二氢铵作为基体改进剂,灰化温度为850 ℃,原子化温度为1 600 ℃时,用氘灯校正背景GF-AAS法进行测定,测定方法的RSD为2.6% ,回收率在92.4%～104%之内。     

石墨炉原子吸收法测定生殖液中铅和镉含量的方法研究

就体液中金属元素的测定方面而言,对生殖液的研究则相对较少。文章建立了测定精液和卵泡液中铅和镉的简洁可靠的方法,对样品的处理、基体改进剂的选择、样品的用量、测定参数的选择等方面进行了研究,方法对铅的加标回收率在99.0%～118%之间,对镉的的加标回收率在96.3%～109%之间。方法的最低检出浓度为铅0.8 μg·L-1,镉0.05 μg·L-1。相对标准偏差在3.74%～8.54%之间。     

微量悬浮液进样-火焰原子吸收光谱法测定霜类化妆品中的铅

基于悬浮液技术处理霜类化妆品样品,将样品悬浮在1.00g/L琼脂溶液中制成均匀的悬浮液,采用微量进样技术建立了火焰原子吸收光谱法快速测定霜类化妆品中的铅。方法的检出限为0.030μg/mL,回收率为98.8%—101.5%。方法应用于实际样品的测定,结果满意。     

微波消解-可见分光光度法测定土壤中的总铬

通过对3种常用微波消解实例进行试验,得出了微波消解土壤样品最佳的样品处理条件和仪器控制条件,优化了土壤中总铬的检测方法。以HNO3-H2O2-HF消解体系消解土壤样品效果最佳,该方法测定总铬的检出限为5m g/kg,两个土壤样品5次平行测定的RSD分别为0.49%和1.98%,加标回收率分别为97.30%和98.20%。微波消解-可见分光光度法测定土壤中的总铬是一种快速、准确、节约酸用量且低环境污染的检测方法。     

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.