便携式气相色谱仪测定岩溶地下水中的苯系物

建立了吹扫捕集-便携式气相色谱仪测定岩溶地下水中苯系物的方法.利用氩气吹扫-Carboxen捕集阱富集,采用MXT(R)200毛细管柱进行分离,微氩离子检测器测定岩溶地下水中的苯系物.对吹扫时间、解析温度等影响因素进行了优化选择,较好的分离和测定了苯系物.当样品体积为20mL时,苯系物组分的检出限为0.86μg/L,方法加标回收率在91％-106％之间,相对标准偏差均小于5％.     

吹扫捕集-气相色谱检测卷烟包装材料中的苯系物

采用吹扫捕集-气相色谱联用,对卷烟包装材料中的苯系物、苯甲醛和苯酚10种挥发性有机物进行检测.本方法的检出限为0.011-0.98ng/cm2;空白样品的加标回收率为95%-111%;相对标准偏差在0.73%-5.33%之间;相关系数0.9991-0.9999.吹扫捕集技术作为样品的不使用有机溶剂的前处理方式,对环境不造成二次污染,具有取样量少、灵敏度高、检出限低、简便快速、结果准确等优点.     

吹扫捕集-气相色谱-质谱法测定地下水中苯系物的不确定度评定

依照《测量不确定度评定与表示》,对吹扫捕集-气相色谱-质谱法测定地下水中苯系物的结果进行不确定度评定。分析了测量过程中引入的不确定度来源,包括样品采集瓶体积、标准溶液制备、校准曲线回归、样品稀释过程、吹扫捕集前处理方法对样品回收率等分量引入不确定度及其计算方法,最后合成标准不确定度,通过乘以95%概率下的扩展因子2,获得测量结果的扩展不确定度。     

环境样品中总汞测定方法的建立——吹扫-金柱捕集-(双柱)热脱附-冷原子荧光法

基于美国环境保护局(U.S.Environmental Protection Agency,USEPA)1631方法,自制双柱热脱附装置,以国产AF-610B型原子荧光仪为检测器,搭建吹扫-金柱捕集-(双柱)热脱附-冷原子荧光系统,用于测定环境样品中的总汞。对吹扫流速、吹扫时间和尾吹流速等实验参数进行了优化。双柱热脱附装置的脱附效率为99%—100%。在最优测定条件下,仪器检出限为5.0pg,海水测定的方法检出限为0.50ng/L,土壤、沉积物和红树样等固体样品测定的方法检出限为1.0ng/g。采用基底加标回收率法和参考样,验证了该系统的准确可靠性。结果表明,海水、土壤、沉积物和红树植物组织等样品的基底加标回收率均符合USEPA的限定范围,土壤参考样(ESS-4)和近海海洋沉积物参考样(GBW07314)的测定结果在参考值的可控范围内。该系统可满足环境样品中总汞测定的要求。     

吹扫捕集与气相色谱-质谱联用测定水体中的芳烃化合物

利用吹扫捕集-气相色谱-质谱联用技术,对化工厂附近有可能受污染的地表水进行了定性和定量分析。同时对吹扫捕集的试验条件进行了优化,得到了满意的结果。     

快速声表面波气相色谱技术检测水中苯系物*

建立了便携式声表面波气相色谱快速检测水中苯系物的方法。实验条件:检测器温度25℃,DB-5毛细管色谱柱:初始温度40℃,10℃/s程序升温至180℃。结果表明,氯苯、间二甲苯、苯乙烯、异丙苯保留时间分别为1.72 s、1.86 s、2.00 s、2.22 s,检出限分别为1.34μg/L、0.55μg/L、0.50μg/L、0.39μg/L,测得相对标准偏差值为4.08%~5.98%,回收率为82.7%~103.8%,且线性良好,线性相关系数为0.9946~0.9993。因此,该方法适用于水中苯系物的快速应急监测。     

吹扫捕集气相色谱法分析化妆品中挥发性化合物

建立了同时测定化妆品中7种挥发性化合物的吹扫捕集气相色谱法（PT-GC）,该方法最大的优点就是不用任何有机溶剂对样品萃取和浓缩,减少了对环境的污染,具有灵敏度高、检出限低、定量准确、操作简便等特点。结果表明：此方法有较好的重复性,相对标准偏差在6%以下;检出限为0.3056-7.1373ng/mL;7种物质的回收率在80.87%—107.15%之间。     

匀浆提取-气相色谱/质谱联用法测定卷烟主流烟气中的苯并[a]芘

研究了用匀浆提取-气相色谱/质谱联用法测定卷烟主流烟气中苯并[a]芘的方法,卷烟主流烟气样品用剑桥滤片捕集,匀浆法提取滤片上捕集的苯并[a]芘,然后采用气相色谱-质谱联用法进样分析.结果显示该方法检测出的苯并[a]芘含量和国家标准相符合,并具有提取完全、效率高、能耗低的特点.     

顶空固相微萃取法用于饮用水源水中苦味酸的间接测定

建立了间接测定饮用水源水中苦味酸的前处理方法——顶空固相微萃取法(HS-SPME)。用带65μm聚二甲基硅氧烷-二乙烯基苯(PDMS-DVB)涂层的固相微萃取柱顶空萃取水中苦味酸与次氯酸钠的反应产物——氯化苦(硝基三氯甲烷),氯化苦用气质联用仪检测,采用质谱的选择离子模式和内标法进行定量。实验优化了萃取条件,如萃取柱涂层、水样与次氯酸钠体积比例、样品体积、预反应时间、盐度、样品pH、反应和萃取的温度、萃取时间等。使用优化后的条件,获得方法检出限和校准曲线r分别为0.8μg/L和0.9950。线性范围2.0—20.0μg/L;饮用水源水加标回收率均值和相对标准偏差分别为106.5%和9.0%(n=6)。方法适用于饮用水源水中苦味酸的间接测定。     

南方某县乡镇饮用水中挥发性有机物的检测及风险评价

在南方某癌症高发县5个乡镇10个村进行布点取样,采集深层地下水与浅层地下水共计20个水样。采用吹扫捕集与气相色谱-质谱联用方法测定水样中13种挥发性有机物(VOCs),检出二氯甲烷、三氯甲烷、苯和四氯化碳4种VOCs,其浓度分别为0.36—13.52、0.41—18.71、0.57—11.75μg/L和1.56—214.62μg/L。1个水样中苯和16个水样中四氯化碳超过GB 5749-2006规定的限值。采用优化的USEPA风险评价模型,对VOCs进行人体健康风险评价,其非致癌风险指数0.0073—0.7100,致癌风险水平1.98×10-6—1.99×10-4,全部水样的致癌风险水平超过10-6水质监控值,1个水样的致癌风险水平超过10-4的可接受水平。四氯化碳对非致癌风险指数和致癌风险水平贡献最大。     

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.     

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.     

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.