高效液相色谱法测定金菊泡腾片中绿原酸的含量

采用Nucleosil C18(250mm×4.6mm,4.5μm)色谱柱,以甲醇-磷酸水溶液(pH=3.0)为流动相,其比例为25∶75,检测波长为327 nm,流速1.0 mL/min,柱温29 ℃,建立金菊泡腾片和双黄连口服液中绿原酸含量的高效液相色谱(HPLC)测定方法.绿原酸浓度在0.02-0.1 mg/mL与峰面积积分值呈良好的线性关系,A=0.9394C 0.3674(r=0.9991).该方法灵敏、简便、重现性好、结果准确,可用于金菊泡腾片中绿原酸含量的测定和产品质量控制.     

苦瓜中维生素C含量的测定

建立苦瓜中维生素C含量直接测定新方法。以10%盐酸溶液为溶剂,采用紫外分光光度法测定含量。维生素C在0—10μg/mL浓度范围内与吸光度呈良好的线性关系,回归方程为：y=0.04746C＋0.00109,r=0.9997。检出限为0.023μg/mL,加标回收率在94.8%—101.1%之间。该法操作简单,干扰离子少,结果准确,测量快速、准确度和灵敏度高,可应用于维生素C含量的测定。     

水果、蔬菜中维生素C含量的测定——紫外分光光度快速测定方法探讨

本文利用维生素C具有对紫外产生吸收和对碱不稳定的特性,建立了紫外分光光度快速测定水果、蔬菜维生素C含量的新方法.维生素C浓度在1.00-12.0μg/mL范围内与吸收值呈良好的线性关系;检出限为0.014μg/mL;加标回收率在97.9%-99.0%之间.该法操作简单,结果准确,应用于维生素C含量的测定,结果令人满意.     

分光光度法测定柚子中的维生素C

柚子是一种含维生素C较高的水果,采用2,4-二硝基苯肼法对柚子中的维生素C含量进行测定.先进行波长扫描,确定维生素C的最大吸光度在510nm.然后绘制校准曲线,得到校准曲线方程y=0.0545x+0.053(r=0.9992),测定矮晚柚的平均维生素C含量为75.89mg/100g.并做了3个柚类品种的加标回收实验,回收率都在90％以上,说明此种方法准确率高,方法可行,可用于水果、蔬菜维生素C含量的测定.     

反向高效色谱法测定维生素E中α-V_E含量

采用反相高效液相色谱法测定维生素E中α-VE的含量。C18柱为色谱柱。甲醇/水（100∶0）为流动相,流速为1.0mL/min.检测波长为292nm。线性范围50—100μg/mL,r=0.9993,维生素E中α-VE的含量为84.82mg/L。本法操作简便,样品分离效果好,回收率高,结果准确可靠。     

HPLC测定潮州柑果肉中维生素C

利用HPLC测定了潮州柑果肉中维生素C的含量,以Agilent ZORBAX Eclipse XDB-C18为分析柱,柱温为25℃,进样量为10μL,甲醇-0.1%的草酸溶液（5∶95）为流动相,流速为1mL/min,检测波长为254nm进行分析检测,结果表明,维生素C的出峰时间为1.976min,采用外标法进行定量,在维生素C浓度为20—100μg/mL范围内与峰面积有良好的线性关系,相关系数达到0.9995,加标回收率为97.71%—102.16%之间,平均加标回收率为99.78%,RSD为1.68%（n=6）。此方法能快速,准确的测定潮州柑果肉中维生素C的含量,且重复性好。     

高效液相色谱法测定梅县沙田柚果肉中维生素C的含量

建立了一种高效液相色谱测定沙田柚果肉中维生素C含量的方法。采用0.2%的盐酸为提取剂,VenusilXBP-C18色谱柱,0.02mol/L醋酸铵溶液-甲醇(体积比70∶30)作流动相,流速1.0mL/min,柱温40℃,DAD检测器,检测波长265nm。在40—320μg/mL浓度范围内,维生素C含量与色谱峰面积有良好的线性关系,线性回归方程为y=48.785x-276.96,相关系数r=0.9996(n=5),测定回收率为99.31%—101.87%。该法快速、稳定,能准确测定沙田柚果肉中维生素C的含量。     

高蛋白食品中甜蜜素的检测

使用蛋白沉淀剂将食品中蛋白质去除后,用配有氢火焰离子化检测器的气相色谱对高蛋白样品中的甜蜜紊进行检测。该方法可准确测定高蛋白食品中甜蜜素含量,相关系数大于0.999,最低检出浓度为4mg/kg,回收率为93.3%—101.1%。     

紫外光分光光度法测定淫羊藿中维生素C的含量

紫外光分光光度法测定淫羊藿中维生素C含量。测定波长为243nm;维生素C浸提剂为1.0%（V/V）盐酸溶液;维生素C浓度在2—50mg/L范围内与吸光度线性关系良好（r=0.9992,n=3）;回收率在97%—115%之间（n=3）;相对标准偏差都小于6.0%（n=3）;检出限（LOD）和定量限（LOQ）分别为1.33mg/L和4.04mg/L。人工栽培的箭叶淫羊藿、天平山淫羊藿和长蕊淫羊藿鲜叶中维生素C的含量不同。     

RRLC测定葡萄籽超临界CO2萃取液中的原花青素

用高分离度快速分离液相色谱法测定超临界葡萄籽萃取液中原花青素含量。色谱柱:ZorbaxXDB C18(4.6mm×50mm,1.8μm),柱温:40℃;流动相:1.5%乙酸甲醇-1.5%乙酸水(90:10,V/V);检测波长:280nm;进样量:5μL,流速:0.9mL/min。原花青素在0.60—3.6mg/mL(R2=0.9997)范围内峰面积与浓度呈良好线性关系,平均加标回收率为100.6%,RSD=1.07%(n=6)。方法简单、快速、准确、可靠,为原花青素含量测定提供一种新选择。     

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.     

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.     

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.     

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.