水凝胶角膜接触镜材料研究进展

以角膜接触镜材料的基本要求为出发点,在相关文献和专利的基础上综述了目前软性亲水的水凝胶角膜接触镜材料的研究进展及发展趋势.特别针对传统型水凝胶角膜接触镜的透氧和均一成分构建的局限,分别重点介绍了高透氧角膜接触镜材料及互穿网络角膜接触镜材料.前者通过引入硅氧烷成分使角膜接触镜的延长配戴成为可能,后者则通过交联互锁的结构实现了材料的均一性和稳定性,从而为角膜接触镜材料在药物释放和治疗用途上的更广泛应用创造了条件.     

基于角膜接触镜的眼药缓释水凝胶材料研究进展

常用的眼用药物制剂为滴眼剂或者眼膏剂,具有使用不方便、药物利用效率低、易引起副作用、需频繁施用、影响视力等缺点.采用角膜接触镜缓释的眼用药物制剂可克服这些缺点,因而受到研究人员的重视.综述了基于角膜接触镜、适于缓释眼用药物的poly-HEMA(聚甲基丙烯酸羟乙酯)水凝胶、硅氧烷水凝胶、分子印迹聚合物水凝胶以及含离子配体水凝胶的研究进展,并展望了适于角膜接触镜缓释的眼用制剂的水凝胶材料的发展前景.     

共聚物水凝胶接触镜材料的研究

以过氧化苯甲酰(BPO)为引发剂,N-乙烯基吡咯烷酮(NVP)、甲基丙烯酸β-羟乙酯(HEMA)以及甲基丙烯酸酯共聚,制备水凝胶接触镜材料,并研究了该水凝胶的溶胀性能。实验发现,不添加交联剂的情况下,共聚产物即可形成具有交联结构的水凝胶;随NVP含量的增大,水凝胶的平衡溶胀度也增大;少量甲基丙烯酸酯的加入,可较小幅度地降低共聚物水凝胶的平衡溶胀度;TG分析表明,NVP与HEMA二元共聚物水凝胶中的自由水容易脱水,而添加甲基丙烯酸酯可增强水凝胶的抗脱水性能,以甲基丙烯酸乙酯较为明显。     

共聚物水凝胶角膜接触镜材料的离子渗透性研究

以偶氮二异丁腈(AIBN)为引发剂,N-乙烯吡咯烷酮(NVP)单体、甲基丙烯酸-β-羟乙酯(HEMA)单体、γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)单体及交联剂N,N'-亚甲基双丙烯酰胺(Bis)在一定温度下共聚制得软性角膜接触镜材料--水凝胶,并采用池膜测量法研究了钠离子在角膜接触镜材料中的渗透性能.实验发现,随NVP含量的增大,水凝胶的含水量增大,钠离子渗透性能增强;KH570含量小于15%时,钠离子渗透性能随KH570含量的增加而增强,而含量在15%～25%时钠离子渗透性能则降低;交联剂含量增大会降低钠离子的渗透性能,含量以不超过0.7%为宜.     

复合水凝胶角膜接触镜材料的设计与合成

通过高聚物分子设计的方法,以吸水倍率低的HEMA水凝胶为基体材料,以吸水倍率高的PVPP(交联NVP)颗粒为分散相,制备出了具有明显相界面层的复合水凝胶角膜接触镜材料.通过大量实验表明其制备工艺为:PVPP颗粒与单体HEMA的质量比为10:90,致孔剂PEG400为35%(wt,相对于总反应物),BPO为0.4%(wt,相对于反应单体),反应混合物混合均匀后立即压片、放入温度为75℃的水浴中,反应12h.为下一步研究具有药物缓释功能的、可重复利用的角膜接触镜奠定了基础.     

环境敏感水凝胶的环境扫描电镜观察

采用环境扫描电镜(ESEM),观察环境敏感水凝胶在自然状态下微观结构.对环境参数进行了优化,观察到温敏水凝胶的真实形貌和多孔结构.改变ESEM成像条件组合包括压力、温度和相对湿度等环境条件,在2℃～50℃和300Pa～600Pa的环境条件下,原位和动态观察分析温敏水凝胶的结构变化和退溶胀响应速度等环境敏感特性.     

蛋白质在水凝胶角膜接触镜上的吸附及对膜渗透性能的影响

以牛血清白蛋白(BSA)为模型蛋白,通过紫外分光光度法测定了BSA在共聚物水凝胶膜材料上的吸附量．研究了泪液中蛋白质在甲基丙烯酸-β-羟乙酯和N-乙烯基吡咯烷酮(HEMA—NVP)亲水性共聚物水凝胶的吸附情况．结果表明,蛋白质的吸附量随着吸附时间的增长而增大,4天基本达到吸附平衡．蛋白质在水凝胶上的吸附量随着水凝胶的平衡含水量增大而增大,吸附的蛋白质降低了水凝胶的离子通透性和透氧性．     

共聚物水凝胶的合成及其溶胀性能研究

以过氧化二苯甲酰(BPO)为引发剂，合成了N-乙烯基吡咯烷酮(NVP)-甲基丙烯酸肛羟乙酯(HEMA)-甲基丙烯酸丁酯(BMA)共聚物水凝胶，可作为软性角膜接触镜材料。探讨了不同比例的NVP、HEMA、BMA对材料溶胀性能的影响。     

高分子水凝胶材料研究进展

综述了高分子水凝胶材料的制备方法及应用研究进展，概述了当前的研究热点，并展望了高分子水凝胶材料今后的发展。     

NVP-HEMA角膜接触镜材料的透氧性能

以过氧化二苯甲酰(BPO)为引发剂，N-乙烯基吡咯烷酮(NVP)和甲基丙烯酸β-羟乙酯(HEMA)在一定温度下共聚得水凝胶，可作为软性角膜接触镜材料．实验发现，随NVP含量的增大，水凝胶的含水量越大，透氧性增大，水凝胶材料的透氧率(Dk／L)的倒数与其厚度成正比．并自行设计了一套角膜接触镜材料透氧性能的测试装置、     

Interference based marking method for toric contact eye lens inserts

Toric contact eye lenses are designed to address general blurring that occurs due to uneven cornea which is known as astigmatism. For proper functioning of toric lenses their orientation with respect to the eye is critical. So toric lenses are manufactured with some form of marking which helps in deciding the orientation with respect to the eye. In this research paper a novel marking method based on the interference principle is proposed for toric lenses. Mathematical modeling followed by experiments was done to prove the concept of interference based marking. The proposed marking method is a mask-less, single step clean process.     

X-Ray Microanalysis in the Variable Pressure (Environmental) Scanning Electron Microscope

Electron-excited x-ray microanalysis performed in the variable pressure and environmental scanning electron microscopes is subject to additional artifacts beyond those encountered in the conventional scanning electron microscope. Gas scattering leads to direct contributions to the spectrum from the environmental gas, as well as remote generation of x rays by electrons scattered out of the focussed beam. The analyst can exert some degree of control over these artifacts, but depending on the exact situation, spurious elements can appear at the trace (< 0.01 mass fraction), minor (0.01 mass fraction to 0.1 mass fraction), or even major (> 0.1 mass fraction) levels. Dispersed particle samples give the least compromised results, while fine scale microstructures are the most severely compromised. Procedures to optimize the situation based upon specimen preparation as well as spectral processing are described.     

In situ ESEM investigations of the oxide growth on hot work tools steel: effect of the water vapour

Abstract

Tempered martensitic steel modified AISI H11 is used in forging processes where tool failure can result from the combination of thermo-mechanical and chemical damage. A better knowledge of the oxidation mechanisms in this material could be useful for a better appreciation of its service behaviour and lifetime. The low chromium content of this Fe–Cr type steel allows the development of mainly Fe_2–xCr_xO₃ oxides with corundum structure and leads to enhanced oxidation in the presence of water vapour.

In situ FEG–ESEM images show the scale microstructural modifications during high temperature exposure, as well as the lateral growth of oxide particles. Together with GIXRD, SEM/EDS and SIMS analysis, FEG–ESEM also allows assessment of the H₂O effect on oxidation behaviour during high temperature exposures (600 and 700°C). Water vapour induces either pores or crystallites size increase, favours faceted oxides particles with enhanced density at the highest partial pressure. At this microscopic scale, anisotropic growth of crystallites is observed, and size expansion rates are found to be linear and characteristic of each individual particle.

Temperature acts principally on oxide film microstructure. Whatever the environment, homogeneous scale growth is observed at 600°C whereas the steel surface is heterogeneously covered by oxides at 700°C.     

扫描电子显微镜成像信号分析

介绍了扫描电子显微镜（SEM）的基本工作原理,着重分析了在SEM初始电子束作用下,各种成像信号产生的方式及其特点,确定二次电子信号因成像分辨率高、携带成像信息丰富而成为SEM的最终信号源。针对此信号在实际应用中暴露出的缺陷,介绍了解决办法,从而使SEM的成像性能得以大幅提高,使用范围大为扩展。