介孔材料合成的研究

有序介孔材料作为一种多孔的纳米结构材料，被广泛用作非均相催化剂、各类载体和离子交换剂等，在催化、吸附、分离、传感器以及光、电、磁等许多领域有着潜在的应用价值。近年来备受关注，已成为国际上跨学科的研究热点之一。综述了介孔材料的分类、结构特点、生成机理、制备和表征方法，展望了介孔材料合成的研究趋势。     

一种改进的视网膜图像中微小动脉瘤的检测算法

基于糖尿病性视网膜病变中最早出现的微小动脉瘤病症进行了研究,提出一种有效的微小动脉瘤检测算法。首先在传统模板匹配算法的基础上提出了一种动态多参数模板匹配算法,并且使用相对误差和与相关系数来共同制约匹配度,从而实现了更为精确的匹配提取;其次提出了基于分布特性的计分策略和自适应加权的汇总策略,避免了单纯采用各个特征量作为独立约束指标进行筛选时忽视各个特征量的约束力大小的弊端。实验结果表明,该检测算法能够有效地提高微小动脉瘤的检测真阳性率。     

The synthesis and characterization of the molecular sieve SAPO-16 as well as other SAPO and CoAPO phases using bis(cyclopentadienyl) cobalt(III) hydroxide as a structure directing agent

The clathrate type molecular sieve SAPO-16 was prepared via a hydrothermal synthesis using bis(cyclopentadienyl)cobalt(III) hydroxide, Cp₂CoOH, as a template and characterized by XRD, FT-IR, UV-Vis and SEM. Additionally, the preparation and characterization of possibly new isostructural SAPO-UTD-3 and CoAPO-UTD-3 materials is reported.NSF Presidential Young Investigator 1991–1996.     

Interpolymer complex microparticles based on polymethacrylic acid‐chitosan for oral insulin delivery

In the present study, microparticles composed of polymethacrylic acid‐chitosan (PMAA‐CS) were prepared by a novel interionic gelation method. Free‐radical polymerization of methacrylic acid was carried out in the presence of CS, using a water‐soluble initiator, and application of these microparticles toward oral insulin delivery was evaluated. Microparticles obtained were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) studies. From SEM studies, it was observed that microparticles had an aggregated morphology with size ～20 μm, while FTIR confirmed the presence of ionic interaction between PMAA and CS chains. Protein loading was done by diffusion filling method, and from in vitro release study, it was observed that insulin‐loaded microparticles displayed a pH depended release profile at alkaline/acidic pH. Microparticles exhibited sustained release of insulin for 3–4 h at neutral pH, and enzyme linked immunosorbent assay (ELISA) proved that encapsulated protein maintained 100% biological activity at neutral pH. Preliminary study suggests that these microparticles can serve as good candidate for oral protein delivery. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 506–512, 2006     

Viscoelastic properties and morphology of sulfonated poly(styrene-b-ethylene/butylene-b-styrene) block copolymers (sBCP), and sBCP/[silicate] nanostructured materials

Self-assembled organic/inorganic hybrid materials were created via domain targeted sol-gel reactions of tetraethylorthosilicate in solution with sulfonated poly(styrene-b-[ethylene-co-butylene]-b-styrene) (sSEBS) copolymers. Dynamic mechanical analyses (DMA) of these hybrid materials suggest that the silicate component preferentially incorporates within the sulfonated polystyrene (PS) domains. An irreversible order-order transition (OOT) for unmodified SEBS, sSEBS, and the organic/inorganic hybrids was identified using DMA in shear mode. The OOT temperature increases with sulfonation as well as by adding a silicate phase by the sol-gel process. The DMA results imply a morphological shift with sulfonation, and reflect modified interactions within and between phases. Atomic force microscopy (AFM) indicated a shift from hexagonally packed cylinders in unmodified SEBS to a lamellar morphology in the sulfonated materials, but silicate incorporation did not affect the morphology or domain dimensions. The latter result is evidence for sol-gel polymerization templating in a self-assembly process. The phase-separated morphology is stable up to the degradation temperature of the polymer and thermogravimetric analysis revealed that the degradation temperature is unaffected by silicate incorporation. Small angle X-ray scattering data are in harmony with the structures revealed by AFM in terms of degree of order and scale of features. These results are largely rationalized in terms of chain mobility restrictions due to hydrogen-bonding interactions between different sulfonated PS blocks, an increase in the PS-ethylene/butylene block mixing parameter, increased interfacial surface tension and chain restrictions posed by inserted silicate nanostructures in the case of the hybrid materials.     

Synthesis and characterization of porous media produced by a sol-gel method

Mesoporous silica materials were synthesized by sol-gel method using tetraethoxysilane (TEOS) as precursors and surfactants i.e., cetyltrimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and polyoxyethylene cetyl ether (Brij 56) as templates. Surfactant templates were completely removed by calcination to form mesoporous structure. The effects of type and amount of surfactants on the characteristics of samples were studied. The textural characteristics such as surface area, pore volume, pore size, and pore size distribution were determined by nitrogen sorption isotherms. Fourier transform infrared (FTIR) spectroscopy was employed to qualitatively identify the chemical functionality and to confirm the removal of surfactant template. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to directly observe surface morphology and mesoporous structure, respectively. The adsorption capacity of the synthesized adsorbent for toluene vapor was examined. We found that the pore volume and pore size of mesoporous materials affected the adsorption capacity. The sample prepared with high content of CTAB under basic condition (pH ∼7) yielded large pore volumes and pore sizes and subsequently possessed the high adsorption capacity for toluene vapor.     

Preparation of Mesoporous Ni–alumina Catalyst by One-step Sol–gel Method: Control of Textural Properties and Catalytic Application to the Hydrodechlorination of o-dichlorobenzene

Mesoporous Ni–alumina catalysts (Ni–alumina-pre and Ni–alumina-post) were synthesized by one-step sol–gel method using micelle complex comprising lauric acid and nickel ion as a template with metal source and using aluminum sec-butoxide as an aluminum source. The Ni–alumina catalysts showed relatively high surface areas (303 m²/g for Ni–alumina-pre and 331 m²/g for Ni–alumina-post) and narrow pore size distributions centered at ca. 4 nm. Highly dispersed Ni particles were observed in the Ni–alumina catalysts (ca. 5.2 nm for Ni–alumina-pre and ca. 6.8 nm for Ni–alumina-post) after reduction at 550 °C, while a catalyst prepared without a template (NiAl-comp) exhibited inferior porosity with large metal particles (ca. 12.3 nm). Mesoporous Ni–alumina catalysts with different porosity were obtained by employing different hydrolysis step of aluminum source. When aluminum source was hydrolyzed under the presence of micelle complex, a supported Ni catalyst with highly developed framework mesoporosity was obtained (Ni–alumina-post). On the other hand, when aluminum source was pre-hydrolyzed followed by mixing with micelle solution, the resulting catalyst (Ni–alumina-pre) retained high portion of textural porosity. It was revealed that the hydrolysis method employed in this research affected not only textural properties but also metal-support interaction in the Ni–alumina catalysts. It was also found that the Ni–alumina-pre catalyst exhibited weaker interaction between nickel and alumina than the Ni–alumina-post, leading to higher degree of reduction in the Ni–alumina-pre catalyst. In the hydrodechlorination of o-dichlorobenzene, the Ni–alumina catalysts exhibited better catalytic performance than the NiAl-comp catalyst, which was attributed to higher metal dispersion in the Ni–alumina catalysts. In particular, the Ni–alumina-pre catalyst showing 1.5 times higher degree of reduction and larger amounts of o-dichlorobenzene adsorption exhibited better catalytic performance than the Ni–alumina-post catalyst.     

Web信息抽取技术综述*

快速高效地获取网页主题信息的需求使得Web信息抽取技术成为信息技术领域的研究热点。现有的Web信息抽取技术大致可以归纳为基于统计理论的、基于视觉特征的、基于DOM树结构的和基于模板的几类。由于网页文本本身具有树结构并且具有一定的相似性,基于DOM树结构和基于模板的抽取技术发展很快而且已经得到了广泛的应用。分别论述了上述几类技术在近几年来的研究进展,从自动化程度、适用范围和复杂性三个角度分析对比了几类技术的优缺点。     

基于运动区域检测的运动目标跟踪算法*

针对传统基于模板匹配的运动目标跟踪算法存在着计算量大、模板漂移导致跟踪失败的问题,提出了一种基于运动区域检测的运动目标跟踪算法。该算法通过采用光流法对目标运动区域进行估计,计算出光流场区域的形心,确定待匹配图相匹配范围,再用模板框在已确定区域进行模板匹配跟踪。根据某开放实验室行人录像跟踪实验表明,本算法能够有效解决模板漂移问题,提高了跟踪实时性, 实现了视频对象目标的跟踪。     

改进SSR算法在人脸识别中的应用

为提高人脸检测中人脸验证的速度,在平方积分图像和图像窗口的灰度均值及方差快速计算基础上,对传统的SSR算法中人脸验证算法部分进行了改进。应用改进的算法,结合窗口灰度标准化的计算和平均人脸模板的取得,引入相关系数和平均偏差,加快了求解速度,克服了由于噪声点的存在对真实的候选脸图像漏检的情况。人脸检测实验证明应用改进的模板匹配算法的正确性.