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51.
The diffusion of sucrose through an optically opaque oil-in-water emulsion was monitored nondestructively by measuring the ultrasonic velocity as a function of height. Initially, a corn oil-in-water emulsion (0, 5, 10, 15, or 20 wt% oil) stabilized by Tween 20 (1 wt%) and xanthan (1 wt%) was placed in a measurement cell at 30°C. A 20 wt% sucrose solution containing the same concentration of Tween 20 and xanthan as the aqueous phase in the emulsion was placed on top of the emulsion. The ultrasonic velocity of this two-layer system was measured as a function of sample height and time and then converted into sucrose and oil concentration–distance profiles using empirical calibration curves. The translational diffusion coefficient of the sucrose in the upper and lower layers was determined by fitting the experimental data to a Fickian diffusion model. The measured diffusion coefficients of the sucrose molecules decreased as the droplet concentration in the emulsion increased, indicating retardation of the sugar molecule movement. Ultrasonic profiling was also used to monitor the compression of the emulsion due to movement of water molecules into the upper layer. 相似文献
52.
Erem Bilensoy Yasemin Çırpanlı Murat Şen A. Lale Doğan Sema Çalış 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):363-370
Human Papilloma Virus (HPV) infections are the major cause of cervical cancers. To achieve a better therapeutic efficacy and patient compliance in the treatment for HPV-induced cervical cancers, anticancer agent 5-fluorouracil has been formulated in a vaginal gel using the thermosensitive polymer Pluronic® F127 together with alternative mucoadhesive polymers e.g., hyaluronic acid, Carbopol 934 and hydroxypropylmethylcellulose. To increase its aqueous solubility and to achieve the complete release of 5-FU from the gel, the drug was incorporated as its inclusion complex with 1:1 molar ratio with either β-cyclodextrin or hydroxypropyl-β-cyclodextrin. Following the characterization of drug:CD complexes, thermosensitive gel formulations containing different mucoadhesive polymers and the drug in free or complexed form were characterized in vitro by determining the gelation temperature and the rheological behavior of different formulations along with the in vitro release profiles of these formulations in pH 5.5 citrate buffer. It was observed that complexation with cyclodextrin accelerated the release of 5-FU with the exception of formulation containing Carbopol 934 as mucoadhesive polymer. As far as rheological properties are concerned, favorable thermosensitive in situ gelling properties were obtained with formulations containing HPMC as mucoadhesive polymer. Complete release of 5-FU from gels were obtained with both complexes of β-CD and HP-β-CD and cytotoxicity studies against HeLa human cervical carcinoma cells demonstrated that 1% 5-FU:CD complexes were equally effective as 1% free 5-FU indicating better therapeutic efficacy with lower dose. 相似文献
53.
Production of submicron-sized multihollow polymer particles by alkali/cooling method 总被引:5,自引:0,他引:5
Submicron-sized styrene-methacrylic acid copolymer particles, which were produced by emulsion copolymerization, were changed to those having multihollow structure by treating stepwise the emulsion as follows. First alkali treatment was carried out at higher temperature than the glass transition temperature and subsequently the emulsion was cooled by keeping it at room temperature. This was named alkali/cooling method. The effects of methacrylic acid content, pH, time and temperature in the alkali treatment on the formation of multihollow structure were clarified.Part CLV of the series Studies on suspension and emulsion 相似文献
54.
单体极性对甲基丙烯酸甲酯/丙烯酸丁酯/甲基丙烯酸钠无皂乳液共聚合的影响 总被引:1,自引:0,他引:1
研究了少量甲基丙烯酸钠(NaMA)存在下单体极性对甲基丙烯酸甲酯(MMA)/丙烯酸丁酯(BA)无皂乳液共聚合的影响.单体极性降低,使粒径减小、聚合速率提高、乳液表面张力和粘度降低、粒子表面电荷密度增大、聚合物分子量提高.MMA/NaMA无皂乳液聚合物只呈现一个玻璃化温度Tg,BA/NaMA无皂乳液聚合物呈现两个Tg,MMA/BA比为2∶1~1∶2的MMA/BA/NaMA无皂乳液聚合物呈现四个Tg,这是由于粒子外面相对富含OSO-3和COO-基聚合物的亚层溶解了较多的水,使BA向粒子中心扩散,MMA向外扩散,造成组成差异和相分离而引起的. 相似文献
55.
采用双乳液法研制配糖蛋白B的肠溶微胶囊,考察了微胶囊的形态、粒径及其分布,在摸拟肠液的缓冲液中进行溶解释放试验。配制了两种口服微胶囊混悬制剂,并考察了它的稳定性。 相似文献
56.
乳状液膜法提取L-谷氨酸的研究徐占林(四平师范学院化学系四平136000)严忠张河哲(东北师范大学化学系长春130024)关键词L-谷氨酸乳状液膜载体萃取中图分类号O623.736氨基酸作为重要的生化产品,广泛应用于食品、饲料、医药、化工等许多领域,... 相似文献
57.
研究了烷基硫酸钠纯度,烷基碳链分布对甲基丙烯酸甲酯种子乳液聚合反应的影响。结果表明,烷基硫酸钠中乙醇不溶物含量的增加,可提高MMA乳液聚合反应速度,在采用K2S2O8-NaHSO3-Cu^2+三元氧化-还原引发体系的MMA乳液聚合中,Fe^2+降低反应速率,而Fe^3+则提高聚合反应速率; 相似文献
58.
Xiangrong Chen Xiaobin Ding Zhaohui Zheng Yuxing Peng 《Colloid and polymer science》2005,283(4):452-455
PNIPAAm-b-PPG-b-PNIPAAm triblock copolymers were prepared by redox polymerization. The self-assembly behavior and thermosensitive property of the copolymers in water were studied using 1H-NMR, TEM and a UV spectrophotometer. The results showed that the LCST of the copolymers was 32 °C, which was consistent with that of pure PNIPAAm. The copolymers could form a vesicular structure in an aqueous solution by self-assembly. The hollow structure of the PNIPAAm-b-PPG-b-PNIPAAm vesicles combined with the temperature-sensitive property may enable many potential applications of the vesicles. 相似文献
59.
60.
阳离子无皂含氟丙烯酸酯的合成与表面性能 总被引:1,自引:0,他引:1
在合成甲基丙烯酸全氟辛酰氧基乙酯(FA)基础上,用半连续法制备了无皂阳离子含氟丙烯酸酯乳液。当乳液的粒径在100~200 nm、ζ电位大于40 mV时,乳液较稳定。阳离子亲水单体甲基丙烯酰氧乙基三甲基氯化铵(DMC)在含氟丙烯酸酯中质量分数为0.10~0.18、固含量小于20%时乳液的稳定性好,且随DMC含量的增加稳定性提高;含氟丙烯酸酯乳胶膜的附着力与耐磨性好,乳胶膜的透湿率随DMC的增加而增加。随热处理温度的提高,膜表面自由能下降;经160℃热处理后膜发生了交联,表面自由能为18 mN/m,与聚四氟乙烯(PTFE)的表面能相近,DMC含量对膜表面自由能影响不大。XPS分析也表明膜表面氟含量随热处理温度的提高而增加。 相似文献