Dual‐Active‐Site Nature of Magnesium Dichloride‐Supported Cyclopentadienyl Titanium Chloride Catalysts Switched by an Activator in Propylene Polymerization

MgCl₂‐supported metallocene catalysts often show peculiar catalytic aspects, which are partially similar to both non‐supported complexes and traditional Ziegler–Natta catalysts. In this study, the active‐site natures of various MgCl₂‐supported cyclopentadienyl Ti chloride catalysts are systematically investigated and compared with traditional catalysts in propylene polymerization. The supported titanocene catalysts offer both metallocene‐type and Ziegler–Natta‐type active‐site natures according to the details of the preparation and the activation procedures. The observed dual‐active‐site natures are plausibly correlated with the valence and charge states of the Ti center.

     

创伤性腹壁缺损修补材料的生物相容性及其应用

背景：近年来修复腹壁缺损的方法有了改进与创新,生物材料的应用使腹壁缺损的修复效果有所改观,明显降低了各种腹壁疝的复发和巨大缺损修复后腹壁疝的发生。 目的：评价不同腹壁缺损修补材料临床应用的效果及修补后与宿主的生物相容性。 方法：以 “腹壁缺损,修补,聚丙烯补片,硅胶膜,黏膜,移植,相容性”为中文关键词,“abnormal wall defect; repair; polypropylene patch, silica gel, mucous membrane, transplant, compatibility”为英文关键词,采用计算机检索2005-01/ 2010-10相关文章。纳入与创伤性腹壁修复材料学相关及不同修补材料在腹壁缺损中应用的文章。 结果与结论：目前临床上用于修复腹壁缺损的材料比较多,曾经尝试过多种腹壁修复材料,主要有以下两类：生物性材料包括自体组织(如阔筋膜、肌皮瓣、自体真皮等)、同种异体组织(如羊膜、硬脑膜等)、异种异体组织(如猪心包膜、膈肌、牛腹膜等)。非生物性材料包括金属网织物(如银、铂合金、不锈钢等)、高分子化合物(如Malex,Teflon,Dacron等)。膨体聚四氟乙烯是目前应用较多的腹壁修补材料,但其抗感染能力较差,一旦感染往往需要移去补片。因此寻找优良的生物、植物材料或自体、异体复合材料势在必行。 关键词：腹壁缺损;修补;聚丙烯补片;硅胶膜;黏膜;移植;生物相容性 doi:10.3969/j.issn.1673-8225.2011.12.029     

改性聚合物表面的润湿与液膜特性

现行商用塑料规整填料表面润湿性差,改性前后聚丙烯（PP）表面液膜流动特性均缺乏系统研究。利用聚合物表面改性和表面粗糙方法,大幅改善了PP表面对水的润湿性,成膜率从约40%提高到约95%。PP改性前,液膜在两边缘厚度增加明显,与中间平均膜厚相比,最大增厚可达460%;改性后液膜在表面基本铺展,整个宽度上液膜厚度分布均匀。研究了PP改性前后不同液体流量和气速对液膜厚度和波动的影响,结果发现小液体流量和通气下均大幅加剧液膜波动。     

Modulation of Intestinal Transport and Absorption of Topotecan,a BCRP Substrate,by Various Pharmaceutical Excipients and Their Inhibitory Mechanisms of BCRP Transporter

Breast cancer resistance protein transporter (ABCG2/BCRP) is highly expressed on the intestinal epithelial membrane and has a significant impact on the oral absorption of topotecan. In this study, we examined 6 pharmaceutical excipients including BL-9EX, Brij97, Cremophor EL, Labrasol, Pluronic F68, and Tween 20 for their BCRP inhibitory effects. A bidirectional transport study using Caco-2 cells demonstrated that Tween 20 and Cremophor EL significantly increased the absorptive transport of topotecan, while simultaneously decreasing secretory transport. Interestingly, Labrasol selectively increased absorptive transport, whereas Pluronic F68 selectively decreased the secretory transport, of topotecan. Further investigation using an in situ closed loop experiment showed that 0.05% (w/v) Tween 20 and Cremophor EL significantly increased the intestinal absorption of topotecan in rats. An LDH assay demonstrated that 0.05% (w/v) Tween 20 and Cremophor EL did not cause significant damage to intestinal epithelial membranes. Furthermore, we examined the absorption-enhancing mechanisms of these excipients and found that Cremophor EL, Tween 20, and Labrasol increased the membrane fluidity of the inner lipid bilayers of the intestine. Therefore, this might be one of the most important mechanisms for inhibition of BCRP function by these excipients in the intestine.     

羊膜基质/聚丙烯复合补片的制备及其生物相容性评价

制备脱细胞羊膜基质, 运用物理方法将其复合于临床用聚丙烯补片, 以形成具有更好组织相容性的生物补片。通过细胞培养, 以聚丙烯膜为对照, 评价复合生物补片的细胞相容性;通过动物皮下植入实验, 以评价复合补片的组织相容性。结果表明, 复合补片羊膜基质表面上的成纤维细胞生长和形态均好于聚丙烯表面, 细胞增殖较快, 增殖率超过聚丙烯表面的50%。动物实验显示, 复合补片周围增生少, 无明显纤维包膜形成, 初期在植入周围有淋巴细胞等炎性细胞浸润, 随着羊膜逐渐降解, 4周时可见毛细血管新生;而对于聚丙烯材料, 植入处纤维包囊明显, 炎性情况也较严重。经羊膜基质复合的聚丙烯补片具有良好的细胞和组织相容性。     

聚丙烯纤维驻极体过滤材料的抗菌性能研究

目的研究聚丙烯纤维驻极体过滤材料的抗菌性能。方法采用振荡瓶试验、载体试验和安德森采样器方法,对聚丙烯纤维驻极体过滤材料的抗菌效果和细菌气溶胶过滤效果进行了观察。结果制备的聚丙烯纤维驻极体滤材置于振荡瓶中18h对液体中金黄色葡萄球菌和大肠杆菌的抑菌率分别为96.02%、89.43%;对阻留在聚丙烯纤维驻极体过滤材料上的金黄色葡萄球菌气溶胶作用30min,平均抑菌率为45.22%。该过滤材料对金黄色葡萄球菌和大肠杆菌气溶胶的过滤效率分别为98.89%和99.20%。结论聚丙烯纤维驻极体过滤材料具有较好的抗菌性能,对细菌气溶胶有较好的过滤效果。     

Experimental Study on a Microwave Composite Forming Process Based on a SiC Mold for Manufacturing Fiber Metal Laminate

The microwave composite forming (MCF) process can reduce manufacturing cost because the process time is reduced by the dielectric heating of the mold and the composite material. In a previous study, the MCF process using a commercial microwave oven with a polytetrafluoroethylene mold was applied. Disadvantages of the previous MCF process have been investigated. These included the difference in tensile properties according to the cutting location, absence of a method to measure temperature during the MCF process, and the fact that the input power cannot be controlled according to the temperature. To solve these problems, a microwave oven with a silicon carbide mold was proposed in this study. Uniaxial tensile tests were conducted to obtain the tensile properties of the fiber metal laminate (FML) specimen. In addition, a microscopic image was captured to investigate the non-adhesive area. The tensile properties and thickness distribution of the FML specimens manufactured by the proposed and previous MCF processes were compared according to the cutting location of the FML sheets. Furthermore, the non-adhesive area was quantified to compare the processes. The results revealed that the proposed MCF process improved the tensile properties of the FML specimen and reduced the non-adhesive area.