无花果多糖的分离、纯化和鉴定

经脱脂、沸水抽提、乙醇沉淀、酶-Sevag法脱蛋白得到粗多糖,再经DEAE-Sepharose fast flow阴离子交换层析和Sephadex G-200葡聚糖凝胶柱层析得到纯化的无花果多糖(FCPS),用红外光谱和紫外光谱分析鉴定该多糖.红外光谱分析具有典型的多糖特征吸收峰,紫外光谱分析未见蛋白质(280 nm)与核酸(260 nm)的特征吸收峰.结果表明,所提取的无花果多糖为单一组分的多糖.     

Synthesis of MgAl2O4 Spinel Nanometer Powder via Biology Polysaccharide Assisted Sol-Gel Process

A novel and cost-effective sol-gel process for preparation of MgAl₂O₄ spinel nanometer powders has been developed in this study. A solution of magnesium and aluminum nitrates in stoichiometric proportion was successfully embraced in the biology polysaccharide gel network, formed by the synergistic interaction between xanthan gum (XG) and locust bean gum (LBG) utilizing their broad-spectrum stability of salt tolerance and character of transformation from sol to gel on the condition of proper temperature and relative proportion of polymeric components. Dry gel could be obtained by vacuum dehydration of aqueous gel at low temperatures. Monolithic MgAl₂O₄ spinel nanometer powders were produced by calcining the dry gel above 800°C, with average crystallite size of 20 nanometers.     

二安替比林（3,4—二甲氧基）苯基甲烷光度法测定茶叶中锰

在碱性介质中，加热时空气氧化Ｍｎ为Ｍｎ，Ｍｎ与二安替比林苯基甲烷反应生成橙色产物，吐温２０和乳酸起到协同增敏作用，λｍａｘ＝４６０ｎｍ，ε＝７．８×１０＾４Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，锰量在０－１２μｇ／２５ｍｌ范围内符合比尔定律。     

Studies on mass production of transformed Panax ginseng hairy roots in bioreactor

The growth properties of Panax ginseng hairy roots transformed by Agrobacterium rhizogenes were compared between flask and aerated column or stirred bioreactor. In flask cultures, sucrose, initially 30 g/L, was nearly exhausted after 45 d of culture. The pH of the medium dropped from 5.5 to 4.96 after 10 d, but afterward it gradually increased to 6.4. After 45 d, hairy roots grew about 16-folds. The growth rate of hairy roots in air-bubble column or stirred bioreactor cultures was 1.13 (1.11) to 1.23 (1.20) g fresh wt (dry wt)/(g of cells·d), respectively. For both bioreactors, growth was about three times as high as in the flask cultivation.     

GEOENVIRONMENTAL CHARACTERS OF YELLOW (HUANGHE) RIVER SUSPENDED LOAD

Three important characters of the suspended load of the Yellow (Huanghe) River are discussed, i.e. its temporal fluctuation as a function of solar activity, its uneven spatial distribution along the main course and the inevitability of these phenomena as a natural earth process rather than a result of disturbed ecological system caused by human activity. Implications of this understanding with regard to the control of the Yellow River are also discussed.     

Structural Features of a Polysaccharide from Centella asiatica

Centella asiatica has been used as remedy for sodation, stabilization and against lepra, anabrosis1 in the oriental countries. The low-molecular-weight constituents in Centella asiatica have been investigated1. However, no polysaccharides have been reported. 1BI was the first polysaccharide isolated from C. asiatica, which had immunostimulating activity in vitro. In present study, we report the structural features of 1BI. Experimental Extraction, isolation and purification Dried C.…     

玉米芯水溶性多糖的分离纯化和抗凝血活性研究

从玉米芯中提取到水提水溶性粗多糖,通过乙醇分级、冻融、凝胶过滤层析,生物测定导向等手段,分离到一种能延长体外凝血时间,而且具有外源抗凝血功能的多糖CCⅢ.CCⅢ对活化部分凝血酶原时间(APTT)无显著影响,但可显著延长体外抗凝血时间(PT).将CCⅢ纯化,经糖组成分析、甲基化、高碘酸氧化、Smith降解和GC-MS分析,确定该多糖结构为:β-(1→4)Glc,(1→3)Xyl构成主链,Glc在6-O处有分枝.平均每10个糖残基有1个分枝,支链由β-(1→3)Xyl,(1→3)Glc构成.     

超高效液相色谱-串联质谱法测定茶叶中游离氨基酸成分

建立了使用超高效液相色谱-串联质谱（UHPLC-MS/MS）高效、快速直接测定茶叶中游离氨基酸的方法。通过对质谱、色谱条件及氨基酸提取条件的优化，以含0.2%（体积分数）甲酸的5 mmol/L乙酸铵水溶液和甲醇为流动相进行梯度洗脱，在电喷雾离子（ESI）源正离子扫描模式下检测，通过UHPLC-MS/MS测定，共解析了茶叶中的20种氨基酸。结果表明，茶氨酸（Thea）、Arg、Asn和Asp在50~500 μg/L范围内线性关系良好，其他氨基酸在10~250 μg/L范围内线性关系良好，相关系数均大于0.99；加标回收率为92.3%~109.2%，相对标准偏差为2.00%~9.88%，检出限为0.001~0.011 mg/L，定量限为0.010~0.053 mg/L。该方法灵敏、准确，具有良好的重复性和稳定性，可有效检测出茶叶中的20种氨基酸及氨基类成分。     

榆耳水溶性多糖的结构特征

用3%三氯醋酸从榆耳子实体中提取出水溶性粗多糖,经乙醇分级、SepharoseCL6B纯化得到单一组分GIA.SepharoseCL6B柱层析测得GIA的相对分子质量为1 26×105.GC分析表明GIA由Man和Glc两种单糖构成,其物质的量比为1 42∶1.多糖GIA经部分酸水解、高碘酸氧化、Smith降解和甲基化分析其结构主要为β(1→3)Man和β(1→3)Glc,且在6～0处构成分枝结构,平均每11个己糖残基有2个分枝,多糖GIA的支链部分由(1→4)Glc构成,末端残基为Man,Glc.     

Steric interactions mediated by multiblock polymers and biopolymers: role of block size and addition of hydrophilic side chains

To a first approximation, the primary structure of many food proteins maybe thought of as a sequence of short hydrophobic and hydrophilic blocks. The influence of this type of structure on the steric-stabilising properties of such proteins has been considered here. In line with previous studies, using Self-Consistent-Field calculations, it has been shown that the presence of such protein molecules can lead to attraction and consequently bridging flocculation of colloidal particles. In the low adsorption energy limit for the hydrophobic groups (−1k_BT), it is found that the steric potential is significantly influenced by the changes in the number of adsorbed segments, as two surfaces are brought together. This is in contrast to the well-known results in the literature for the high adsorption limiting cases, where the number of such segments remains constant. In particular, the changes in the number of adsorbed hydrophobic units are observed not to be a monotonic function of the separation distance, but increase or decrease in reasonable accord with the oscillatory nature of the steric interactions, observed for various block sizes. Effects of the addition of a moderately sized hydrophilic side chain to the above molecules have also been studied. It is found that, in principle, such a modification can lead to a purely repulsive steric potential in solutions of these hybrid biopolymers. At the hydrophilic side chain sizes considered here, the surface affinity of the molecules is observed not to be drastically different compared to those of unmodified proteins.