微波消解-火焰原子吸收光谱法测定毛鸡骨草中的6种微量元素

用浓硝酸微波消解的方法处理样品,采用火焰原子吸收光谱法测定中药毛鸡骨草中Fe、Cu,Mg、Ca、Mn、Zn 6种微量元素的含量.结果表明毛鸡骨草含有丰富的人体必需微量元素,各元素的回收率在98.00%-102.20%之间.该方法操作简单,结果准确,是毛鸡骨草中微量元素测定的理想方法.     

黑米中微量元素含量的测定

采用高压密封消解罐法对样品进行处理,以电感耦合等离子体-原子发射光谱法(ICP-AES)和原子吸收光谱法(AAS)测定黑米中Mn、Cu、Fe、Mg等微量元素的含量,lCP-AES更佳.回收率为92.2%-109%,相对标准偏差小于2.67%.实验证明,黑米含有丰富的对人体有益微量元素,是一种健康食品.     

原子吸收光谱法测定茶叶中7种微量元素

用浓硝酸-过氧化氢处理样品,火焰原子吸收光谱法测定江西龙南县映山红茶叶中Fe、Cu、Ca、Mn、Zn 5种微量元素,用石墨炉原子吸收光谱法测定茶叶中Pb、Cd.所测定的茶叶中含有丰富的人体必需的微量元素,Pb、Cd的含量远远低于国家的限定标准,采用此方法回收率在93.70%-102.40%之间,相对标准偏差小于10%.本方法简单、准确,结果令人满意.     

原子吸收光谱法测定紫菜中微量元素

用原子吸收光谱法对紫菜中铜、铁、锰、镁、钙、锌、铅、镉8种微量元素含量进行测定,方法的精密度、回收率符合分析要求.测定结果表明:紫菜中含有丰富的人体必需的微量元素,而铅、镉等有害元素含量很低,作为食用蔬菜对人体补充微量元素有较高的利用价值.     

头发微量元素分析的科学价值

 以前的人体微量元素状况的检测,是通过体内某些组织和体液的测定来判断的.但这种方法的缺陷在于:采集复杂,保存与运输困难,样品受伦理、观念、时间、功能和组分元素互相转移等因素的限制.80年代初,不少科学家从事头发的微量元素研究,为检测人体微量元素状况开辟了新途径.大家知道,头发是由蛋白质聚合成角朊构成的.在头发生长期,有许多微血管伸入发根中,发的基质细胞与血液、淋巴细胞外液、汗腺密切接触,促使头发不断生长.据介绍,头发中微量元素同人体储备间存在明显的正相关系(图1),取人发作为检测材料可以判断被测人几星期至几年中体内微量元素营养状况与代谢变化.     

扇贝微量元素的测定

以高压硝化罐消化样品,利用电感耦合等离子体原子发射光谱(ICP-AES)法和火焰原子吸收(AAS)法分别测定了扇贝中的Zn,Co,Fe,Mn,Mg,Ca,Cu,K共八种微量元素的含量, 并对两种分析方法进行了分析比较b 结果表明,ICP-AES法和AAS法测定的微量元素无显著性差异, ICP-AES稍优。方法回收率在93.3%～102.8%之间,相对标准偏差均小于1.60%。扇贝含有丰富对人体有益微量元素,不但味道鲜美,而且可以补充人体所必需的微量元素。     

微波消解-火焰原子吸收光谱法测定板栗壳中6种微量元素

用浓硝酸微波消解样品,火焰原子吸收光谱法测定板栗壳中Fe、Cu、Mg、Ca、Mn、Zn6种微量元素,板栗壳中含有丰富的人体必需微量元素,回收率在98.2%—102.0%之间。本法简单、准确,结果令人满意。     

原子吸收光谱法测定人体血清中的微量元素锌、铜、铁、钙和镁

本法不需要消解样品,样品经分离稀释后,直接用火焰原子吸收光谱法测定人体血清中的锌、铜、铁、钙和镁5种微量元素的含量.该方法简便,快速,精密度高,相对标准偏差(RSD≤8.52%)回收率在95%-100%之间.结果准确可靠.     

火焰原子吸收法测定大豆和豆制品中铁、锌、铜、铬和镍

采用WFX-1型原子吸收分光光度计测定大豆及豆制品中微量元素铁、锌、铜、铬、镍的含量.大豆及豆制品中铁、锌、铜、铬、镍含量丰富,对人体有益.大豆产地不同,其所含微量元素也不同.一般大豆中微量元素含量高者则其豆制品中微量元素含量也高,呈正相关.     

原子吸收光谱法测定新疆不同居群大蒜中微量元素的含量

采用湿法消解处理大蒜样品,用原子吸收光谱法对新疆不同居群大蒜中Ca,Fe,Zn,Mg,Cu,Mn,Cr,Pb和Cd共九种微量元素的含量进行了测定,并进行了加标州收率实验.结果表明:不同居群大蒜中上述微量元素标准曲线的相关系数在0.994 4～0.999 8之间,呈现良好的线性关系;样晶测定结果的相对标准偏差(RSD)均不超过5.15%,各元素的加标回收率在99.4%～101.7%之间,测定结果准确可靠;新疆地产大蒜中对人体有益的微量元素含量较为丰富,不同样品中微量元素含量的差异一定程度上反映了南北疆之间地形地貌、气候、土壤、水文等环境要素的差异.     

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.