高效液相色谱测定海虾中呋喃唑酮残留量

样品用二氯甲烷提取,正己烷纯化、外标法定量,高效液相色谱(HPLC)法检测海虾中呋喃唑酮残留量.本方法校准曲线线性范围为0.01-1.00μg/mL,r=0.9991.检测下限为1.0μg/kg,回收率92.0%-100.5%,相对标准偏差(RSD)为2.9%-4.6%.测定方法准确,灵敏,达到了水产品检测的要求.     

快速溶剂萃取气相色谱法测定蔬菜中六六六和滴滴涕的残留量

建立了蔬菜中六六六和滴滴涕残留量快速溶剂萃取气相色谱的分析方法。该法的α-六六六、β-六六六、γ-六六六、δ-六六六、PP’-滴滴伊、OP’-滴滴涕、PP’-滴滴滴、PP’-滴滴涕检出限均≤0.05μg/L。加标回收率为88.6%—101.1%,相对标准偏差(RSD)小于8%。该法步骤简单快速,适用于蔬菜中六六六和滴滴涕农药的快速检测。     

3种铝分析方法在定量测定海参产品的比较

建立了海参产品中铝残留量的3种定量分析方法,即紫外分光光度法、石墨炉原子吸收光谱法和电感耦合等离子体-质谱法.在各自优化的条件下将3种方法用于铝的检测,比较结果表明:ICP-MS除具有线性范围宽(1-200μg/L),灵敏度高的特点外,还具有简单、快速、体系稳定性好等优点.     

ICP-AES同时测定钼矿石中多种元素

采用碱熔酸化和ICP-AES同时测定钼矿石样品中Mo、SiO2、P2O5、CaO、Fe2O3、S、Cu、Pb、Zn、Sn、As等多种元素,检出限分别为0.1μg/g、0.005%、0.03%、0.003%、0.001%、5μg/g、0.5μg/g、0.7μg/g、0.3μg/g、1.5μg/g、1μg/g;RSD为1.2%-3.8%.该法准确,快速,简便,结果令人满意.     

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.     

方波伏安法测定罗布麻叶中锌含量

使用BAS 100A电化学分析仪,应用方波伏安法测定了罗布麻叶中锌的含量.在NH3-NH4Cl缓冲液(pH=10)中,-860mV峰电位下产生一个灵敏峰,检测罗布麻叶中的锌,以校准曲线法定量.建立了回归方程y(μA)=52.52 1610.79x(μg/mL),相关系数r=0.9582.回收率为97.04%,RSD为0.72%.方法简便快速、灵敏度高.     

标准加入法在能力验证考核酱油铅含量中的应用

采用标准加入法-硝酸钯基体改进剂消除酱油中食盐的机体干扰,建立了标准加入法-硝酸钯基体改进剂GFAAS测定酱油中痕量铅的方法,该方法的检出限为4.2μg/L,精密度为1.52%—4.96%,在5、20μg/L添加水平回收率为91.6%—108.2%,90.5%—101.7%,方法简单、快速、检出限符合标准分析要求。     

高效液相色谱法同时测定饮料中苯甲酸和山梨酸

探讨了同时测定饮品中苯甲酸、山梨酸的分析方法.采用高效液相色谱(HPLC)法分离和检测样品中苯甲酸、山梨酸.将样品除去CO2后,用氨水调节pH=7,滤膜过滤.外标法定量,检测饮料中苯甲酸、山梨酸含量.苯甲酸、山梨酸校准曲线线性范围为0.5-20.0μg/mL,r分别为0.9985和0.9990.检出限分别为0.44μg/mL,和0.32μg/mL,回收率76.3%-105.4%,相对标准偏差(RSD)1.27%-7.67%.使用高效液相色谱法同时测定饮料中苯甲酸山梨酸的方法准确,灵敏,达到了实验方法的要求.     

微波消解-电感耦合等离子体-质谱测定蔬菜中的铅和镉

用微波消解-电感耦合等离子体-质谱测定蔬菜中的Pb和Cd,方法简便、快速.Pb和Cd检出限分别为0.14μg/L和0.13μg/L,相对标准偏差(RSD,n=5)＜4.69%,标准加入法回收率Pb为96.0%-104.0%,Cd为95.0%-110.0%.方法经国家一级植物标准物质验证,结果与推荐值相符.     

电感耦合等离子体-质谱法测定岩石和矿物中的钨和钼

采用高氯酸-氢氟酸-硝酸处理样品,电感耦合等离子体质谱法测定岩石矿物中的钨钼,避免了极谱法中汞对人体的伤害,测定的相对标准偏差（RSD,n=8）小于2.0％.方法的检出限Mo为0.065μg/g;W为0.092μg/g.用不同类型国家一级标准物质验证,结果与标准值吻合较好.该方法适用于岩石矿物中钨和钼的检测,重现性好,灵敏度较高,能满足简单、快速、批量分析要求.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.     

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.     

Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.     

A novel methodology for photometric compensation of projection display on patterned screen

We propose a novel methodology based on the projector-camera (ProCam) system to address the photometric compensation issue for the projection display on the patterned screen.The patterned screen is treated as the combination of a perfect white screen and a color modulator.The perfect white screen is used to automatically and accurately characterize the ProCam system offline using the polynomial model,and the parameters of the color modulator can be efficiently recovered by employing only two gray images based on the linear reflectance model.The experimental results show that the color artifacts of the display image can be greatly improved with this methodology,which demonstrates its feasibility and validity in the photometric compensation.     

Direction-of-arrival estimation using matrix spatial prefiltering approach

An approach to direction-of-arrival （DOA） estimation for multiple narrowband farfield signals is proposed. The technique uses a novel matrix spatial prefiltering approach. Specifically, a matrix filter is designed to spatially filter the incoming data snapshots. The un-wanted components arriving from the stopband angular sectors are attenuated and the desired components from the angular sector of interest pass with minimal distortion. The matrix filter spatially filters the element-space data and the output reserves the element-space data property, which makes it very useful by passing sensor data through a spatial prefilter prior to applying many other array processors to attenuate interferences and improve system performance. Several examples of DOA estimation problem are presented to illustrate the performance of the proposed spatial prefiltering approach. Results of simulation and real data show that the pre-filter can efficiently attenuate the spatial interferences and significantly improve the estimation and resolution capability of DOA estimators at low signal-to-noise ratios for the sources located inside the passband sector. In addition, the use of spatial prefilter makes it possible to estimate DOAs for multiple sources more than the number of the elements of an array.     

Quantum efficiency calibration of opto-electronic detector by means of correlated photons method

A new calibration method of detectors can be realized by using correlated photons generated in spontaneous parametric down-conversion (SPDC) effect of nonlinear crystal.An absolute calibration system of detector quantum efficiency is performed.And its principle and experimental setup are introduced.A continuouswave (CW) ultraviolet (351 nm),diode-pumped,frequency-doubled,and solid-state laser is used to pump BBO crystal.The quantum efficiencies of the photomultiplier at 633,702,and 789 nm are measured respectively.The coincidence peaks are observed using coincidence circuit.Some measurement factors including the filter bandwidth of trigger channel,the detector position alignment and polarization of the pump light are analyzed.The uncertainties of this calibration method are also analyzed,and the relative uncertainties of total calibration are less than 5.8%.The accuracy of this method could be improved in the future.