灵芝多糖结构及其组成研究

采用沸水回流法从赤灵芝子实体中提取多糖,经Sevage法除蛋白,乙醇沉淀,离心、流水透析、浓缩、冻干后得灵芝多糖,单糖经乙酰化处理进行外标法定量,并利用苯酚-硫酸法、紫外、红外及X衍射光谱法、凝胶分子排阻色谱-蒸发散射检测器法、气相和气质谱色谱法进行多糖组分、含量、结构和分子量分析研究,结果表明： 灵芝多糖为米黄色,得率为2%左右,其含量≥43%,红外光谱显示灵芝多糖结构主要为β-糖甘键连接的吡喃型葡聚糖,其多糖的主要单糖组分为葡萄糖,含量为89%左右,并含有其他少量的单糖组分D-阿拉伯糖、D-木糖、D-甘露糖、D-半乳糖。其多糖主要为同均糖,多糖为非晶型结构,分子量主要分布在8×104～2×105之间,分子质量主要为2×105的生物大分子。     

野生糙皮侧耳子实体多糖的脱色素效果比较

用乙醇沉淀法从野生糙皮侧耳子实体中提取水溶性多糖,分别用活性碳,二乙氨乙基(DEAE)纤维素,H2O2,重蒸酚等4种脱色剂进行脱色;并以酵母聚糖为标准品比较脱色效果,用光谱扫描法检测光吸收强度的变化;结果表明,用0.75%浓度的活性碳脱色后,有色杂质的去除效果最好,光谱吸收峰最接近标准品。     

用气相色谱和红外光谱对羧甲基化南瓜多糖结构的研究

采用超声辅助法提取南瓜多糖并对其进行分离和羧甲基化;邻苯三酚自氧化法测定羧甲基南瓜多糖对超氧阴离子自由基的清除作用;气相色谱法、红外光谱对南瓜粗多糖及其组分AP1的化学结构进行了分析.结果表明,羧甲基南瓜多糖能有效清除超氧阴离子自由基,并随着浓度的增加清除作用增强.该结果提示羧甲基南瓜多糖具有抗氧化性.气相色谱证明南瓜多糖由阿拉伯糖、鼠李糖、核糖、甘露塘、果糖、半乳糖、葡萄糖组成.南瓜AP1多糖由阿拉伯糖、鼠李糖、核糖、果糖、半乳糖、葡萄糖组成.红外光谱分析证实南瓜多糖具有糖类物质的特征吸收峰,同时存在呋喃环和吡喃环.     

不同分子量龙须菜多糖对草酸钙结晶的调控作用

植物多糖的化学结构与尿液中的结石抑制剂葡胺聚糖相似,有可能用于预防和治疗肾结石。天然多糖由于分子量和分子体积过大,导致其应用受到限制。研究了四种分子量分别为49.6,16.2,8.2和3.8 kDa的降解龙须菜多糖GLP1,GLP2,GLP3和GLP4对草酸钙(CaOx)晶体生长的调控作用。1H NMR,13C NMR和气相色谱-质谱(GC-MS)谱分析表明四种GLPs由β-D-半乳糖和6-O-硫酸基-3,6-α-L-吡喃半乳糖组成。X射线衍射(XRD)检测表明,在各GLPs存在下,诱导了二水草酸钙(COD)晶体形成,COD的衍射峰出现在晶面间距d=0.617,0.441,0.277和0.224 nm处;而没有多糖存在时只生成一水草酸钙(COM)晶体,COM的衍射峰出现在d=0.593,0.364,0.296和0.235 nm。由于COD比COM更容易排出体外,COD的形成有利于降低结石形成的风险。傅里叶变换红外光谱(FTIR)检测表明,随着GLP分子量减小或GLP浓度增加,草酸根中羧基的不对称伸缩振动ν_as(COO-)和对称对称伸缩振动ν_s(COO-)都发生了不同程度的蓝移,其中ν_as(COO-)从1 618 cm-1增加到1 642 cm-1,ν_s(COO-)从1 318 cm-1增加到1 328 cm-1,即GLP4诱导的全部是COD晶体。扫描电子显微镜(SEM)检测表明,随着GLP分子量减小,不但晶体中COD的比例增加,而且晶体的分散程度增大,晶体更加圆钝。随着GLP分子量减小或GLP浓度增加,其诱导生成的CaOx晶体表面电荷越负,Zeta电位绝对值越大,这有利于抑制晶体的聚集。电感耦合等离子体发射光谱仪(ICP)检测表明,四种GLPs均可以增加溶液中可溶性Ca2+的浓度,同时减少CaOx沉淀的生成量。在浓度为1.0 g·L-1多糖存在时,上清液中可溶性Ca2+的摩尔浓度分别为：GLP4 (37.88 μmol·L-1)>GLP3 (19.70 μmol·L-1)>GLP2 (16.05 μmol·L-1)>GLP1 (10.55 μmol·L-1)。结果表明,四种GLPs均可以抑制COM生长,诱导COD生成,降低晶体的聚集程度,增加晶体表面的Zeta电位绝对值和溶液中可溶性Ca2+浓度,减少CaOx晶体的生成量,且GLPs的调控活性与其分子量呈负相关。这些结果提示GLPs特别是分子量最小的GLP4有可能是防治CaOx结石的潜在药物。     

L-苏氨酸卟啉锌配合物结构及ECD的谱理论研究

采用密度泛函理论方法和极化连续介质模型,对L-苏氨酸卟啉锌的基态几何构型进行了优化;以优化得到的稳定构型为基础,采用含时密度泛函理论进行了电子圆二色谱研究.计算获得ECD谱带形与实验谱基本吻合. 通过对有关跃迁性质的分析对实验谱进行了理论解析.     

L-苏氨酸卟啉锌配合物结构及ECD的谱理论研究

采用密度泛函理论方法和极化连续介质模型,对L-苏氨酸卟啉锌的基态几何构型进行了优化;以优化得到的稳定构型为基础,采用含时密度泛函理论进行了电子圆二色谱研究.计算获得ECD谱带形与实验谱基本吻合. 通过对有关跃迁性质的分析对实验谱进行了理论解析.     

介质阻挡放电中栅栏发光斑图等离子体参量研究

采用高速录像机和光谱仪,研究了在双水电极介质阻挡放电装置中首次得到的由长短交替的棒状放电结构组成的栅栏斑图。通过观察20 μs曝光录像照片发现栅栏斑图由体放电和沿面放电组成。采用发射光谱法,利用N₂第二正带系(C³Π_u→B³Π_g)的发射谱线和Ar Ⅰ(2P₂→1S₅)谱线的展宽,分别测量和比较了不同体放电和沿面放电不同位置处的分子振动温度和电子密度。结果发现:斑图中具有较强沿面放电的体放电比具有较弱沿面放电的体放电拥有较高的分子振动温度和电子密度;在沿面放电的方向上,沿面放电的分子振动温度和电子密度均逐渐降低。理论分析证明,壁电荷在狭缝内的非等量分布是影响栅栏斑图形成的主要因素。     

蒙成药如达多糖的研究

从蒙成药如达中提取水溶性多糖,硫酸-苯酚法测定其含量。平均回收率为99.8%,RSD为0.94%。GC测定了水溶性多糖的组成为葡萄糖、半乳糖和甘露糖。其摩尔比为:6.33:3.25:1.59。     

气质联用法分析枸杞水溶性粗多糖中单糖组成

采用红外、气质联用技术分析了枸杞水溶性多糖中单糖组成及其含量.结果表明,枸杞多糖里含有的单糖包括阿拉伯糖,鼠李糖,木糖,甘露糖,半乳糖,葡萄糖,其含量比例为13.19∶3.41∶2.92∶10.53:18.92:9.82.     

HMQC-TOCSY技术在植物环肽和配糖体中的应用

核磁共振HMQC-TOCSY二维技术可在氢谱方向和碳谱方向分别得到独立的自旋系统内氢核和碳核的全相关信息.该技术对于分子内具有多个自旋系统的植物环肽和配糖体的结构解析尤为适用.本文以环肽annosquamosin A和三萜皂甙prostratoside A为例说明该技术在这两类化合物中的应用.     

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.