Surface Modification of Magnetic Nanoparticles Using Gum Arabic

Magnetite nanoparticles were synthesized and functionalized by coating the particle surfaces with gum arabic (GA) to improve particle stability in aqueous suspensions (i.e. biological media). Particle characterization was performed using transmission electron microscopy (TEM) and dynamic light scattering (DLS) to analyze the morphology and quantify the size distribution of the nanoparticles, respectively. The results from DLS indicated that the GA-treated nanoparticles formed smaller agglomerates as compared to the untreated samples over a 30-h time frame. Thermogravimetric analyses indicated an average weight loss of 23%, showing that GA has a strong affinity toward the iron oxide surface. GA most likely contributes to␣colloid stability via steric stabilization. It was determined that the adsorption of GA onto magnetite exhibits Langmuir behavior.     

Release kinetics of (−)-menthol from chewing gum

The release kinetics of (−)-menthol from chewing gum was investigated using various encapsulated powder of (−)-menthol. The apparatus of flavor release of chewing gum was made with a glass container of mashing homogenizer. Flavor release behavior could be correlated with Avrami’s equation. Chewing gum containing (−)-menthol/γ-CD complex powder had longer retention of (−)-menthol compared with the β-CD complex powder and the (−)-menthol encapsulated in modified starches. The activation energies of (−)-menthol release from chewing gum were 106 kJ/mol for γ-CD complex and 74 kJ/mol for (−)-menthol/β-CD complex powder and emulsified (−)-menthol encapsulated in HI-CAP, respectively.     

邻体干扰推广模型及其在林草生态系统的应用

在对邻体干扰指数模型进行推广的基础上,将其应用于分析林草生态系统（杜仲－三叶草,杜仲－黑麦草,杜仲－蒿类）中杜仲生长速度与草本植物邻体干扰强度的定量关系。     

两次制备薄层色谱分离纯化杜仲叶中的绿原酸

将杜仲叶粉先用氯仿除脂,乙醇超声提取绿原酸,再经适当萃取除杂后、通过两次制备薄层色谱纯化得到绿原酸.产品的紫外光谱特征与文献相符,薄层色谱主斑与绿原酸对照品对应,HPLC的主峰tR与绿原酸对照品的tR吻合.HPLC外标法测得产品绿原酸的纯度为91.6%以上.所建立的纯化制备方法简便、直观、对绿原酸有很好的分离效果,适合于数百毫克级~克级的制备.     

泡沫植物胶特性及其护壁防漏机理

结合某矿区的复杂地质特征,选用4种植物胶进行室内试验遴选,辅以十二烷基苯磺酸钠(ABS)、聚丙烯酰胺(HPAM)、腐殖酸钾为外加剂进行泡沫植物胶基浆配制,探讨植物胶对基浆中膨润土含量、泡沫稳定性能及其流变特性影响的变化规律.研究结果表明:植物胶对膨润土泥浆的流变特性具有明显的改善作用,其防塌护壁作用主要表现为低失水特性、疏水性泡沫吸附孔壁、黏弹性泥饼结构、低流速塞流状态等特性:防漏堵漏作用主要表现为泡沫群体结构屏蔽防漏、泡沫与岩屑聚结充填堵漏、高结构黏度塞流阻流防漏、低密度低压力流体防漏堵漏等特性.     

生物聚合物驱油体系流变性研究

考察了盐、碱、表面活性剂及实验温度对生物聚合物（黄胞胶）驱油体系流变性的影响．研究结果表明，生物聚合物与阴离子表面活性剂（石油磺酸盐）相互作用强烈．在流变性方面体现出良好的协同效应，这种协同效应对低界面张力—流度控制复合驱十分有利．对几类生物聚合物驱油体系，包括聚合物驱、碱－聚合物驱、碱－表面活性剂－聚合驱的不同配方的而变性考察结果表明，在常用的几种描述聚合物溶液流变性的模型中，幂律模型（Ｏｓｔｗａｌｄ模型）的相关性最好     

杜仲中松脂醇二葡萄糖甙的提纯

对杜仲中活性成分松脂醇二葡萄糖甙(PinoresinolDiGlucoside,即PDG)提取、纯化工艺进行了研究,并使用高效液相色谱法测定PDG含量.结果表明:杜仲粉用体积分数为60%的乙醇水溶液,60℃,提取2次,每次1h,PDG提取率可达90%以上.分别采用4种大孔树脂对提取液进行分离纯化处理,以不同浓度的乙醇水溶液进行梯度洗脱,发现S型树脂对此种活性成分选择性好、吸附量大,用体积分数为40%的乙醇水溶液洗脱可将其完全解吸附,PDG的收率达45.2%.在C18色谱柱上,以体积分数为26%的甲醇水溶液为流动相,流速为1.0mL/min,在λ=228nm处,对杜仲原料中PDG进行了测定,结果表明炮制后的杜仲皮的PDG质量分数较高,为0.497%.     

低分子量阳离子瓜胶凝胶体系的流变性

研究了低分子量阳离子变性瓜胶与硼砂交联的凝胶体系。考察了低分子量阳离子瓜胶浓度、硼砂浓度及pH对凝胶形成的影响,得到了结构稳定的凝胶体系。考察了低分子量阳离子瓜胶凝胶体系的流变特性,结果表明该体系具有良好的粘弹性和剪切变稀性。非线性共转Jeffreys模型可确切表征凝胶体系的粘度曲线,实验值与模拟值吻合良好。     

皂荚瓜尔胶的提取及其性能

对皂荚种子中瓜尔胶的提取、含量、结构及其在不同浓度、pH值、剪切力作用下黏度的变化规律进行了试验。结果表明:种子中,内胚乳的含量为410.2 mg/g,内胚乳中瓜尔胶的含量为475.8 mg/g;用红外光谱设备测得其结构符合半乳甘露聚糖结构通式;瓜尔胶溶液的比浓黏度随浓度的升高而增加,瓜尔胶为非牛顿流体,其比浓黏度随剪切力的增大而显著减小;瓜尔胶溶液的特性黏度受pH值的影响甚微,在中性条件下其特性黏度最大。