浊点萃取-高效液相色谱测定鱼体中的痕量多环芳烃

采用阴离子表面活性剂十二烷基硫酸钠(Sodium dodecyl sulfate,SDS)浊点萃取(Cloud Point Extraction,CPE),高效液相色谱法(High performance liquid chromatography,HPLC)测定鱼类样品中痕量多环芳烃(PAHs),考察了适宜的反应条件和影响因素(脱脂pH、脱脂温度、脱脂时间、SDS、HCl和NaCl的用量).在最佳条件下,5种PAHs萘、芴、苊烯、菲和芘的方法检出限分别为:660、780、90、1650、240ng·g-1,线性范围为0-3×105ng·g-1.方法快速、简便、经济,应用于鱼类中痕量PAHs的测定,结果满意.     

水蒸气剥离法纵向脱附模型的数值研究

简要探讨、分析了多环芳烃(PAHs)与土壤颗粒吸附的机理以及相关研究现状,对水蒸气剥离法脱附污染土壤中多环芳烃的数学模型进行数值求解,获得净化后土壤中多环芳烃浓度的理论解以及多环芳烃脱附过程的部分变化规律。同时分析了Peclet数Pe,传质参数β、反应器内停留时间γ等对脱附效果的影响。     

基于密度泛函理论的多环芳烃硝基衍生物的生物毒性预测

采用密度泛函理论（DFT）中的B3LYP方法,在6-311++G（d,p）基组水平下对16种多环芳烃（PAHs）及6种多环芳烃硝基衍生物进行了拉曼光谱、极化率、偶极矩、热力学、结构优化及能量等40种参数进行计算。以13种PAHs对发光菌的－lgEC₅₀值做因变量,以另外3种多环芳烃数据作为验证,构建了基于量子化学参数的PAHs毒性定量结构-活性相关（QSAR）模型,预测PAHs硝基衍生物的毒性。经验证,所建立的QSAR模型的模拟系数为0.816,模型预测的PAHs硝基衍生物毒性排序与文献报道的PAHs硝基衍生物对鼠伤寒沙门氏菌的毒性排序一致,表明所建模型可用于PAHs及其硝基衍生物的生物毒性预测,从而为控制和预测PAHs及硝基衍生物毒性提供理论依据。     

气相色谱-质谱法测定烤羊肉串中的多环芳烃

建立烤羊肉串中多环芳烃的气相色谱-质谱(GC-MS)测定方法。样品经正己烷-二氯甲烷匀浆提取、氧化铝柱净化后,用GC-MS分离测定。在所建立的最佳实验条件下16种多环芳烃完全分离,回收率在77.5%—99.4%,之间,相对标准偏差(RSD)为2.24%—8.70%,检出限为0.009—0.120μg/mL。所建立的分析方法快速、简便,适合16种多环芳烃的检测分析。     

表面增强拉曼光谱技术在多环芳烃检测中的应用

多环芳烃(polycyclic aromatic hydrocarbons,PAHs)是一类致癌性很强的环境污染物.由于PAHs分子不含有能与金属配位或键合的官能团,因此很难利用SERS技术对其进行直接检测.本文综述了近年来表面增强拉曼散射(surface-enhanced Raman scattering,SERS)...     

选择离子储存技术用于分析气溶胶中的多环芳烃

探讨了气质联用结合选择离子储存技术 (GC/MS/SIS)对大气气溶胶中的多环芳烃 (PAHs)进行定性定量分析的可行性。采集的气溶胶样品经索氏提取、吹氮浓缩后进行 GC/MS/SIS分析 ,结果表明完全满足定性及定量分析要求。该法简化了预处理步骤 ,提高了复杂基体中 PAHs分析的灵敏度。     

菲的三维荧光光谱特性研究

多环芳烃(简称PAHs)具有高荧光量子产率,利用三维荧光光谱研究了PAHs中菲的荧光光谱特性.菲具有两个荧光峰.通过对菲的三维荧光光谱的分析,选择在激发波长255 nm、发射波长370 nm对菲进行定量分析.菲溶液在5.0～250.0 ng·mL-1的范围内工作曲线呈线性关系,检出限为3.88 ng·mL-1,相对标准偏差为4.23%(n=5),实验还尝试了对自来水样品的测定,测试效果良好,回收率为90.0%～105.4%.该研究为快速检测水源水中痕量PAHs提供了方法基础.     

气相色谱与质谱联用测定淮安某县乡镇饮用水中的多环芳烃

在淮安某县选取4个镇中的8个村进行布点,分别在2010年7月和12月采集丰水期和枯水期水样,采用固相萃取与气相色谱-质谱联用方法对深层地下水、浅层地下水中的多环芳烃(PAHs)进行检测.检测结果表明,深层地下水在丰、枯水期PAHs总量分别为496.18-1035.06ng/L和82.60-329.03ng/L.浅层地下水丰、枯水期PAHs总量分别为474.69-2310.44ng/L和81.39-518.81ng/L.丰水期PAHs总量高于枯水期.5个水样中苯并(a)芘超标,最大超标0.69倍.采用优化的USEPA风险评价模型,对PAHs进行人体健康风险评价,其致癌风险水平在2×10-8-3.92×10-6之间,部分水样致癌风险超过10-6的水质监控值.     

层流预混火焰PAHs形成的反应机理模型

本文着重讨论层流预混火焰中,碳黑的先驱多环芳烃(PAHs)形成的化学反应动力学机理。该机理包括101种组分、546个基元反应。通过与实验结果的比较表明,该模型能够较好地预报碳氢燃料预混火焰中PAHs的生成过程。计算结果还表明当量比和压力PAHs的生成与排放具有重要影响,且存在一个化学当量比,在此当量比下,PAHs的浓度达到极大值。     

拉曼光谱的16种多环芳烃（PAHs）特征振动光谱辨识

借助密度泛函理论中B3LYP/6-311++G(d, p)方法对美国EPA优先控制污染物中的16种多环芳烃(PAHs)：萘、苊烯、苊、芴、菲、蒽、荧蒽、芘、苯并[a]蒽、稠二萘、苯并[b]荧蒽、苯并[k]荧蒽、苯并[a]芘、二苯并(a, h)蒽、二苯并[g, h, i]芘以及茚苯(1, 2, 3-cd)芘进行结构优化,并计算拉曼光谱振动频率和去偏振度,在此基础上辨识多环芳烃的拉曼特征光谱。研究显示,16种PAHs的拉曼振动主要分布在3个频区：200～1 000 cm-1（指纹区）、1 000～1 700和3 000～3 200 cm-1（基团频率区）,3个频区主要振动归属分别为环变形(ring def),碳碳伸缩(CCStr)、碳氢摇摆(CHw)及其耦合振动(CCStrCCw),碳氢伸缩(CHStr)。进一步分析显示,指纹区16种PAHs的去偏振度随苯环变形振动对称性增强而降低,在该频区去偏振度最小的频移处苯环呼吸振动的对称性最强,指纹区的峰强也在此处出现最大值。任意PAHs在指纹区的最强峰之间的波数差较大,在显微拉曼光谱的可分辨范围内,因而利用指纹区的去偏振度和最强峰可将16种PAHs逐一识别。烷烃、烯烃、炔烃、醇类和酚类、脂肪醚、芳基烷基醚、醛类、酮类、羧酸、酯类、胺类、腈类、酰胺类、酸酐、芳烃的振动频率和峰强分布不完全一致,利用PAHs与这几类物质拉曼频率和峰强分布的差异可以逐一排出干扰。     

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.     

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.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

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.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

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.