植物叶代替茶叶制作松花蛋的研究

用茶叶制作松花蛋是传统工艺的做法,但其成本较高。试验结果表明,山楂叶和柿子叶代替茶叶制作松花蛋,前者在蛋白的凝固方面优于后者,松花蛋的色泽前者比后者浅,但却很鲜艳,并且有很多大而清晰的松花。试验还同时对Zn和Pb的成色作用进行了对比。通过试验结果结合经济效益分析,认为山楂叶和柿子叶可以替代茶叶制作松花蛋。     

Research of Degumming Process, Microstructure and Properties of Mulberry Fiber

More and more novel nature fibers are used in textiles. The natural fibers include banana fiber, pineapple fiber and bamboo fiber etc. In this paper, as a kind of novel natural fiber, mulberry fiber is studied. The chemical component of mulberry bast is tested and analyzed. Meanwhile, the degumming method and process of mulberry bast are studied. Chemical degumming experiments to investigate the influence of alkali concentration, alkali boiling time and sodium phosphate tribasic ratio to material are conducted. Consequently, optimum parameters are obtained. The crystallinity of mulberry fiber is tested by using X-ray line, and the photos of scanning electron microscope （SEM） are observed. Testing results of the fiber properties （e. g. fineness, tenacity, length and elongation） show that mulberry fiber can be spun blend with cotton.     

Phenolic profiles and antioxidant capacities of crude extracts and subsequent fractions from Potentilla fruticosa L. leaves

This work aimed to further investigate the phenolic profiles and antioxidant capacities of the crude extracts and the subsequent fractions of Potentilla fruticosa leaves. Result showed that P. fruticosa leaves contained high amounts for hyperoside, ellagic acid and (+)-catechin contents, and the highest amount being registered for hyperoside (17.67 mg g^?1). Nine sub-fractions were obtained after column chromatographic separation. EF-3, EF-4, EF-5 and BF-2 presented higher values for their total phenolic or flavonoid, (+)-catechin, ellagic acid and hyperoside content. Besides, EF-3, EF-4, BF-2 and BF-3 showed significant in vitro antioxidant capacities and protective effects on Escherichia coli under peroxide stress. The correlation between chromatograms and antioxidant activity showed that (+)-catechin, ellagic acid and hyperoside may play crucial roles in the antioxidant capacities of P. fruticosa and could be used as chemical markers for its quality assessment. Moreover, this is the first time P. fruticosa leaves have been systematically studied.     

Preparation and properties of cellulose/silver nanoparticle composites with in situ-generated silver nanoparticles using Ocimum sanctum leaf extract

In the present work, silver nanoparticles were in situ-generated in cellulose matrix using Ocimum sanctum leaf extract as a reducing agent. Regenerated wet cellulose films were first immersed in O. sanctum leaf extract and then it was allowed to diffuse into the films. The leaf extract–diffused wet films were dipped in different concentrated aq.AgNO₃ solutions. The leaf extract inside the wet films reduced AgNO₃ into nanosilver. The dry composite films were black in color. Some of the nanoparticles were also formed outside the film in the solution. The nanoparticles were viewed by transmission electron microscopy and scanning electronic microscopy techniques. The composite films showed good antibacterial activity. The cellulose, matrix, and the composite films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis techniques. The tensile properties of the composite films were higher than those of the matrix. These biodegradable films can be used for packaging and medical purposes.     

A new cytotoxic diterpenoid glycoside from the leaves of Blumea lacera and its effects on apoptosis and cell cycle

A new diterpenoid glycoside, 6E,10E,14Z-(3S)-17-hydroxygeranyllinalool-17-O-β-d-glucopyranosyl-(1?→?2)-[α-l-rhamnopyranosyl-(1?→?6)]-β-d-glucopyranoside (1) together with the known diterpenoid glycoside (2) and two known flavonoid glycosides (3, 4) were isolated from the methanol extract of Blumea lacera leaves. The structures were determined by the interpretation of their spectroscopic data and comparison with the literature. All compounds were isolated for the first time from B. lacera and evaluated for their cytotoxic activity. Only the new compound (1) showed strong cytotoxic activity with the lowest IC₅₀ value (8.3 μM) being displayed against MCF-7 breast cancer cells. In apoptosis and cell cycle analysis, 1 revealed strong apoptotic activity against MCF-7 cells (45.5% AV⁺/PI^?) after 24 h, but showed no arresting of any of the cell cycle phases in MCF-7.     

桑青枯病病原G12-9内切葡聚糖酶基因的克隆和分类

桑青枯病是一种土传性细菌病害,从广东省桑园发生青枯病的桑树根部分离得到1株病原菌G12-9;经鉴定确定该菌为青枯菌（Ralstonia solanacearum）,该病原菌在TZC固体培养基上呈圆形及不规则圆形,菌落中央呈现淡红色,革兰氏染色成阴性。对G12-9分离株内切葡聚糖酶基因的克隆、序列测定及聚类分析结果表明,桑青枯菌G12-9内切葡聚糖酶属于糖基水解酶家族12。青枯菌最重要的致病性分泌系统为Ⅱ、Ⅲ、Ⅳ型分泌系统,内切葡聚糖酶属于细菌Ⅱ型分泌系统,内切葡聚糖酶对于青枯菌的定植及寄主植物的致病性有着非常重要的作用,明确该酶在糖基水解酶家族的分类地位对桑青枯病的防治具有重要意义。     

荷叶生物碱与DNA相互作用的光谱法研究

采用荧光光谱、紫外-可见光谱和盐效应等手段.研究了荷叶生物碱提取物与小牛胸腺DNA之间的相互作用,并在pH 7.4的Tris-HCl介质中.以中性红为荧光探针对作用机理进行了研究.结果表明:在生理条件下(pH= 7.4),荷叶生物碱提取物与DNA发生作用方式为混合方式,嵌插与沟槽作用是两种主要作用方式,DNA对荷叶生物碱提取物荧光猝灭属于静态猝灭。测得其结合常数为3.765×106 L/mol.     

Statistical mixture design--principal component optimization for selective compound extraction from plant material

A simplex centroid design is used to optimize solvent mixtures for selective extraction of compounds from Erythrina speciosa Andrews leaves. Three main groups of compounds characterized by chromatographic retention times of 1.7, 3.1, and 6.6 min were extracted. The chromatographic peak heights registered at 1407 equally spaced times for each design extract were converted into principal components (PCs). Three PCs account for 89.1% of the data variance and have important loading values at the above retention times. Quadratic mixture models were found to adequately describe the response surfaces of their PC score values. Maximizing the first PC scores while minimizing the second and third ones results in an optimum 83% dichloromethane-17% acetone mixture that selectively extracts the group of compounds with retention times around 3.1 min. Maximizing the second PC scores and minimizing the third PC scores leads to a 78% hexane-22% acetone mixture adequate for extracting the 6.6 min retention time compounds as well as other compounds with high retention times. The 1.7 min group of compounds is most efficiently extracted on maximizing the third PC that results in a 50% ethanol-50% acetone mixture. The Derringer-Suich algorithm confirmed the determination of these optimized mixtures.     

佛山市顺德区基塘农业模式的演变与发展潜力

选择佛山市顺德区作为调查对象,对该区桑基鱼塘分布较多的陈村、谭村和杏坛进行实地调查,分析其基塘农业模式的发展变化与原因,通过遥感技术和A rcG IS技术利用遥感图像对调查地区的基塘农业进行分期对比分析,计算其基塘农业面积的变化,对基塘农业的生态效应、生态优势及其发展前景进行了讨论,提出了基塘农业生态模式将来的发展对策...