等离子清洗处理SERS活性金岛膜表面杂质的研究

采用真空蒸镀法在硅片表面形成了一层具有表面增强拉曼活性的金岛膜.拉曼光谱发现该金岛膜表面存在非晶态碳的污染物.通过比较不同清洗方法的拉曼光谱可以证明,用氧气等离子体清洗金岛膜可有效去除金表面的杂质.金岛膜的表面增强拉曼活性在清洗前后没有发生明显变化.     

Preferential heights in the growth of Ag islands on Si(1 1 1)-(7 × 7) surfaces

Growth behavior of thin Ag films on Si substrates at room temperature has been investigated by scanning tunneling microscopy and reflection high energy electron diffraction. In the layer-plus-island growth Ag islands show strongly preferred atomic scale heights and flat top. At low coverage (1 ML), islands containing two atomic layers of Ag are overwhelmingly formed. At higher coverages island height distribution shows strong peaks at relative heights corresponding to an even number (2, 4, 6, …) of Ag atomic layers. Beyond some coverage the height preference vanishes due to the appearance of screw dislocations and spiral growth.     

Identification of the magnetic island structure in the HL-2A tokamak

The identification of the magnetic island structure in the HL-2A tokamak is presented. First, the perturbation current as a source for the perturbation flux can be determined by using Mirnov probe measurements. By superposing the perturbation flux and the equilibrium flux reconnected by equilibrium fitting, the structure and the width of the magnetic islands can be estimated. The method has been used in the HL-2A experiments.     

高温下金属薄膜生长初期的模拟研究

采用实际的生长模型和物理参量,用Monte Carlo方法对高温下金属薄膜的生长过程进行了模拟研究.综合考虑了原子沉积、扩散、成核、生长和扩散原子的再蒸发、原子沿岛周界扩散和岛的合并等众多过程后,模拟得到与实验结果相当一致的薄膜生长形貌及其相应的定量结果.通过动态统计薄膜生长过程中的岛数目及薄膜生长率,得到实验中不易直接获得的高温下薄膜生长的许多细节,如岛数目和薄膜生长率随表面温度、覆盖度变化的详细情况等 关键词： 薄膜 Monte Carlo模拟 成核 岛密度 薄膜生长率     

银岛膜表面胸腺嘧啶吸附行为的表面增强拉曼光谱和表面增强红外光谱研究

利用激光刻蚀法制备了具有化学纯净表面的银岛膜,该岛膜有很好的表面增强特性。利用表面增强拉曼光谱和表面增强红外光谱对胸腺嘧啶分子在银岛膜表面的吸附状态进行了对比研究。表面增强拉曼光谱中CN和C—O伸缩振动模式的出现表明胸腺嘧啶分子由原来的酮式结构变成了烯醇式结构;C(4)O伸缩振动谱带明显增强和N(3)的去质子化异构体特征峰的存在证明胸腺嘧啶分子是通过O(8)和N(3)的共同作用倾斜地吸附在银岛膜表面。对10-5 mol.L-1胸腺嘧啶在银岛膜表面上的红外光谱利用欧米采样器进行了反射法测量,发现其红外吸收增强了200倍。红外信号分析的结果支持了胸腺嘧啶分子通过O(8)与银表面发生相互作用的论断,同时也可得出胸腺嘧啶倾斜地吸附在银岛膜表面的结论。     

Improved fluorescent assay sensitivity using silver island films: Fluorescein isothiocyanate-labeled albumin as an example

We have studied enhancement of the fluorescence of fluorescein isothiocyanate (FITC), bound to albumin and near an annealed silver island film, as a function of the distance between the protein molecules and the metal. As the intermediate spacer layer between the albumin and the silver substrate, we used multilayer films based on polyelectrolytes. The maximum nine-fold enhancement coefficient for the fluorescence of FITC corresponds to a thickness of the intermediate layer of ≈4 nm, or three layers of the polyelectrolyte. In this case, we observe a significant decrease in the average photoluminescence decay time for the label near the silver film compared with a dielectric medium. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 797–800, November–December, 2006.     

胃癌细胞MGC803中LTF基因的表达及其启动子甲基化相关性研究

目的 检测胃癌细胞株MGC803内乳铁蛋白（LTF）基因的甲基化和表达情况,探讨LTF的DNA 启动子区甲基化异常 与其在胃癌内表达的相关性。方法 用亚硫酸氢盐测序PCR 方法检测MGC803 启动子区甲基化状态,使用real-time PCR 和Western blot 分别检测LTF 在MGC803内的mRNA 和蛋白表达水平。同时使用去甲基化剂5-aza-CdR 处理胃癌细胞株,观察给药前后的DNA 甲基化状态和mRNA 表达情况。结果 MGC803 启动子甲基化率达59.8%,使用5-aza-CdR 处理的两组（2滋mol/L组和10滋mol/L组）和空白对照组甲基化率差异、LTF 的mRNA表达差异均有统计学意义（均P＜0.05）,并且随着MGC803启动子甲基化程度的下降,其mRNA 和蛋白表达增加;而不同浓度药物处理组间差异均无统计学意义（均P＞0.05）。结论 LTF 基因在胃癌细胞株MGC803 内表现为较高甲基化状态,而且LTF的表达和其启动子区甲基化情况相关,使用去甲基化剂能逆转DNA 的甲基化情况从而使其mRNA 重新表达。     

Nanovesicles Loaded with Origanum onites and Satureja thymbra Essential Oils and Their Activity against Food-Borne Pathogens and Spoilage Microorganisms

Food poisoning is a common cause of illness and death in developing countries. Essential oils (EOs) could be effective and safe natural preservatives to prevent and control bacterial contamination of foods. However, their high sensitivity and strong flavor limit their application and biological effectiveness. The aim of this study was firstly the chemical analysis and the antimicrobial evaluation of the EOs of Origanum onites L. and Satureja thymbra L. obtained from Symi island (Greece), and, secondly, the formulation of propylene glycol-nanovesicles loaded with these EOs to improve their antimicrobial properties. The EOs were analyzed by GC-MS and their chemical contents are presented herein. Different nanovesicles were formulated with small average sizes, high homogeneity, and optimal ζ-potential. Microscopic observation confirmed their small and spherical shape. Antibacterial and antifungal activities of the formulated EOs were evaluated against food-borne pathogens and spoilage microorganisms compared to pure EOs. Propylene glycol-nanovesicles loaded with O. onites EO were found to be the most active formulation against all tested strains. Additionally, in vitro studies on the HaCaT cell line showed that nanovesicles encapsulated with EOs had no toxic effect. The present study revealed that both EOs can be used as alternative sanitizers and preservatives in the food industry, and that their formulation in nanovesicles can provide a suitable approach as food-grade delivery system.     

城市典型地物的热辐射特性研究

运用热红外技术监测地表温度已获得成熟的发展,城市化进程的加快使得城市热岛效应日益显现,有关城市典型地物热辐射特性的研究对于分析城市热岛现象的成因和分布具有重要意义。本文通过对保定市地面实测数据的研究发现,地物类型、观测时间和墙面朝向是影响城市典型地物热辐射亮度温度的主要因素。结果显示,地物类型的不同显著影响其亮度温度,但仍存在同谱异物现象;不同时间观测到的地物热辐射强度不同,且在很大程度上影响其在各通道上的亮温差异;不同朝向墙面的亮温也有差异,且这种差异随观测时间而改变。对城市典型地物热辐射特性的研究具有理论和实践意义,为热红外遥感监测城市热岛效应提供了依据。