基于同步辐射显微CT技术研究冻干口腔崩解片的精细结构

采用低温冰颗粒直压冻干法制备口腔崩解片,与模制冻干法相比较,以同步辐射显微CT技术(SR-μCT)观测片剂内部的精细结构,得到显示内部结构差异的切片图,构建三维模型,确定灰度阈值后,提取片剂子结构,定量分析子结构,同时测定片剂的崩解性质和脆碎特征,研究片剂内部精细结构与其药剂学性质的关系。SR-μCT观测结果显示,不同制备工艺、处方所得的口腔崩解片的精细结构存在显著的差异,模制冻干法得到一体化致密网状结构,而低温冰颗粒直压冻干法得到松散聚集状态颗粒结构,这些结构特征合理地解释了低温冰颗粒直压法所得冻干口腔崩解片崩解迅速的机制,其微观子结构决定了片剂结构力学的宏观性质。结果显示,SR-μCT表征制剂内部精细结构的研究对阐明速释制剂的崩解特征有重要意义。

Effects of cryogenic cold air jet cutting on chip break in metal machining

The half-dry cutting employs cryogenic compressed air cooled down to (10 to 40) and a micro-dosage of lubricating oil, called cryogenic cold air jet cutting was studied. On the basis of a comparative experiment on dry and cryogenic cold air jet cuttings carried out for grade 45 steel, the effects of cryogenic cold air jet on the breaking of chips were discussed. The experimental results reveal that in the valid ranges of pressure and temperature, the cryogenic cold air jet widens the chip breaking areas effectively. When the cutting depth is not greater than 1 mm, the influence of chip breaking is much more significant. But different injecting angle of cold air has different influence on the chip-break. From the experiment, the optimized jet injecting angle, temperature effecting range and pressure working range of cold air are obtained. These results can offer a foundation for industrial manufacturing.