激光辐照猫眼光学镜头时的反射特性机理研究

运用矩阵光学理论以及将硬边光阑窗口函数展开为有限个复高斯函数之和的方法, 对激光束辐照猫眼光学镜头时产生的猫眼效应机理进行了理论推导. 通过数值计算对猫眼效应的反射规律进行了分析, 并利用532nm激光辐照一个变焦范围为12—72mm的光学镜头进行了猫眼效应的实验验证, 从而得出了猫眼效应反射光特性与入射激光参数以及猫眼光学镜头的口径、焦距、离焦量等基本参数之间的关系. 研究表明, 猫眼效应反射光特性与猫眼光学镜头参数和入射激光参数密切相关, 且当猫眼光学镜头位于近场和远场的情况有很大不同. 根据入射光束 关键词： 猫眼光学镜头 猫眼效应 高斯光束 反射特性     

Simultaneous determination of 405 pesticide residues in grain by accelerated solvent extraction then gas chromatography-mass spectrometry or liquid chromatography-tandem mass spectrometry

A new method has been established for simultaneous determination of 405 pesticide residues in grain, using accelerated solvent extraction (ASE), solid-phase extraction (SPE), and GC-MS and LC-MS-MS. The method was based on appraisal of the GC-MS and LC-MS-MS characteristics of 660 pesticides, their efficiency of extraction from grain, and their purification. Samples of grain (10 g) were mixed with Celite 545 (10 g) and the mixture was placed in a 34-mL cell of an accelerated solvent extractor and extracted with acetonitrile in the static state for 3 min with two cycles at 1,500 psig and at 80°C. For the 362 pesticides determined by GC-MS, half of the extracts were cleaned with an Envi-18 cartridge and then further cleaned with Envi-Carb and Sep-Pak NH₂ cartridges in series. The pesticides were eluted with acetonitrile-toluene, 3:1, and the eluates were concentrated and used for analysis after being exchanged with hexane twice. For the 43 pesticides determined by LC-MS-MS the other half of the extracts were cleaned with Sep-Pak Alumina N cartridge and further cleaned with Envi-Carb and Sep-Pak NH₂ cartridges. Pesticides were eluted with acetonitrile-toluene, 3:1. After evaporation to dryness the eluates were diluted with acetonitrile-water, 3:2, and used for analysis. In the linear range of each pesticide the linear correlation coefficient r was equal to or greater than 0.956 and 94% of linear correlation coefficients were greater than 0.990. At low, medium, and high fortification levels, at the limit of detection (LOD), twice the LOD and ten times LOD, respectively, recoveries ranged from 42 to 132%; for 382 pesticides, or 94.32%, recovery was from 60 to 120%. The relative standard deviation (RSD) was always below 38% and was below 30% for 391 pesticides, or 96.54%. The LOD was 0.0005–0.3000 mg kg⁻¹. The proposed method is suitable for determination of 405 pesticide residues in grain such as maize, wheat, oat, rice, and barley, etc.      

聚3-氯噻吩修饰CdSe纳米棒复合膜电极光电化学性能研究

采用水热法制备了具有闪锌矿和纤维锌矿结构的CdSe纳米棒. 纳米棒直径约为100 nm, 长度约为300 nm. 当外加电极电势为-0.6 V 时, 经聚3-氯噻吩[Poly(3-chlorothiophene), P3CT]修饰的CdSe纳米棒具有最大光电流, 并且CdSe/P3CT复合膜电极最高光电转换效率(IPCE)为13.5%, 低于CdSe纳米棒膜电极17.7%的最高IPCE. CdSe/P3CT复合膜电极中存在p-n异质结, p-n异质结的存在使得CdSe/P3CT复合膜电极在长波区(>410 nm)的IPCE整体高于CdSe纳米棒薄膜电极的IPCE.     

前驱体法制备Mn_2O_3空心橄榄形结构及形貌演化

利用苹果酸还原高锰酸钾以水热合成方法制备了具有橄榄形貌的纳米结构MnCO3前驱体,通过600℃焙烧MnCO3前驱体得到橄榄形Mn2O3.以扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、热重-差热分析(TG-DTA)等方法对产物的形貌和结构进行了表征.考察了MnCO3前驱体微观形貌随水热反应时间的演变:当水热反应时间为2h时得到具有橄榄形形貌的MnCO3前驱体,空心结构的壁比较厚;当水热反应时间延长到6h时得到的MnCO3前驱体仍然具有橄榄形形貌,壁变薄;当反应时间延长到24h时得到的MnCO3前驱体仍然具有橄榄形形貌,并且壁非常薄.我们推测在Ostwald熟化机理作用下,空心橄榄形MnCO3前驱体随着反应时间的延长其壁逐渐由160nm演化为30nm.     

Insight into STM image contrast of n-tetradecane and n-hexadecane molecules on highly oriented pyrolytic graphite

Two-dimensional ordered patterns of n-tetradecane (n-C₁₄H₃₀) and n-hexadecane (n-C₁₆H₃₄) molecules at liquid/graphite interface have been directly imaged using scanning tunneling microscope (STM) under ambient conditions. STM images reveal that the two different kinds of molecules self-organize into ordered lamellar structures in which alkane chains of the molecules extend along one of three equivalent lattice axes of highly oriented pyrolytic graphite (HOPG) basal plane. For n-C₁₄H₃₀ molecules, the molecular axes are observed to tilt by 60° with respect to inter-lamellar trough lines and the carbon backbones of the alkane chains are perpendicular to the HOPG basal plane in an all-trans conformation. However, for n-C₁₆H₃₄ molecules, the molecular axes are perpendicular to lamellar borders (90°) and the planes of the all-trans carbon skeletons are parallel to the graphite basal plane. The results clearly indicate that outmost hydrogen atoms of the alkane chains dominate atom-scaled features of the STM images. That is, in the case of long-chain alkane molecules, topographic effects dominantly determine STM image contrast of the methylene regions of the alkane chains that are adsorbed on HOPG.     

杂化太阳电池中异质结界面的修饰及其对电池光电性能的影响

有机-无机杂化太阳电池综合了有机、无机材料的优点,成本低、理论效率高,受到人们的广泛关注.杂化太阳电池的光活性层由无机半导体和有机共轭聚合物复合而成.当光照射到活性层上时,共轭聚合物吸收光子产生激子(电子-空穴对);激子迁移到有机给体-无机受体的异质结界面处发生解离而产生自由电子和空穴;自由电子和空穴分别向无机半导体和有机聚合物传输,从而实现电荷的分离和传导.激子在有机-无机异质结界面处的分离效率是影响电池性能的一个重要因素.有机、无机两相材料往往因为接触面积小以及相容性差使此两相材料接触不佳,激子迁移到此界面不能有效分离,从而严重影响了杂化太阳电池的效率.这个问题可以通过此界面的修饰加以改善.本文即综述了有机-无机异质结界面修饰的方法、作用和意义,并展望了杂化太阳电池未来的发展趋势和应用前景.     

Three-Dimensional Analytical Formula for Oblique and Off-Axis Gaussian Beams Propagating through a Cat-Eye Optical Lens

Based on the Collins formula in a cylindrical coordinate system and the method of introducing a hard aperture function into a finite sum of complex Gaussian functions, an approximate three-dimensional analytical formula for oblique and off-axis Gaussian beams propagating through a cat-eye optical lens is derived. Numerical results show that a reasonable choice of the obliquity factor would result in a better focus beam with a higher central intensity at the return place than that without obliquity, whereas the previous conclusion based on geometry optics is that the highest central intensity could be obtained when there is no obliquity.     

Z箍缩内爆的MARED程序数值模拟分析

MARED程序是模拟Z箍缩内爆过程的二维三温辐射磁流体力学程序,它适用于不同装置条件和不同负载参数.利用MARED程序对Z箍缩内爆进行模拟,结合丝阵Z箍缩实验分析表明:相同负载质量条件下,钨丝阵内爆产生的X射线辐射功率远大于铝丝阵产生的X射线功率;相同负载电流条件下,负载质量越大,计算得到的X射线功率越低;X射线功率随着负载电流增加而增加.MARED程序能够较好地反映Z箍缩内爆动力学过程,特别是不稳定性发展的二维图像,能够给出与不稳定性简化模型的理论分析及实验结果定性一致的演化规律.MARED程序模拟丝阵填充泡沫形成辐射场的初步计算得到了与Sandia实验室模拟Z装置上丝阵填充泡沫定性一致的结果.     

Determination of clopidol residues in chicken tissues by liquid chromatography: collaborative study

Eighteen laboratories participated in a collaborative study on the determination of clopidol residues in chicken muscle tissues by liquid chromatography. Of these, results from 16 laboratories which rigorously followed the method were subjected to statistical analysis. The method performance was assessed by all participants using 14 samples of chicken muscle fortified at concentrations ranging from 0.1 to 5.0 mg/kg. In addition, 9 participants each reported results for 6 clopidol-incurred samples in chicken muscle. Test portions were extracted with acetonitrile, and the extracts were purified with alumina and anion exchange resin solid-phase extraction cartridges in sequence. Clopidol was separated by reversed-phase liquid chromatography and quantified at 270 nm. Average recoveries ranged from 81.8 to 85.4%, reproducibility relative standard deviation (RSDR) ranged from 11.9 to 22.6%, and repeatability relative standard deviation (RSDr) ranged from 9.9 to 15.1%. For clopidol-incurred samples at concentrations of 0.100-0.687 mg/kg, the mean determination value range was 0.099-0.659 mg/kg; RSDR was 12.6-19.8%, RSDr was 3.1-8.5%; and HORRAT values were 0.7-1.1. The accuracy and precision of the method are in conformity with the requirements specified by AOAC INTERNATIONAL. The method was adopted Official First Action in April 2003.     

Simultaneous determination of 16 sulfonamides in honey by liquid chromatography/tandem mass spectrometry

A method is described for the determination of 16 sulfonamides in honey. Samples are dissolved in phosphoric acid solution (pH2), cleaned up with 2 solid-phase extraction (SPE) cartridges, an aromatic sulfonic cation-exchange cartridge and an Oasis HLB SPE cartridge, and analyzed both qualitatively and quantitatively by liquid chromatography/tandem mass spectrometry (LC/MS/MS) under the selected conditions. Without exception, calibration curves were linear (r = > 0.995), when sulfamethizole was between 1.0 and 25.0 microg/kg; sulfacetamide, sulfapyridine, sulfadiazine, sulfachloropyridazine, sulfamethoxazole, sulfamerazine, sulfisoxazole, sulfamonomethoxine, and sulfadoxine were between 2.0 and 50.0 microg/kg; sulfamethoxypyridazine, sulfadimethoxine, and sulfathiazole were between 4.0 and 100.0 microg/kg; sulfamethazine and sulfameter were between 8.0 and 200.0 microg/kg; and sulfaphenazole was between 12.0 and 300.0 microg/kg. Average recoveries at 4 fortification levels in the range of 1.0-300 microg/kg in honey were 70.9-102.5%, and relative standard deviations were 2.02-11.52%. The limits of quantitation for the 16 sulfonamides were between 1.0 and 12.0 microg/kg, with the LC/MS/MS method.