Melting recrystallization processes of melt sheared films of polypropylene（S28C） fractions have been investigated in situ by polarized optical microscope equipped with CCD camera and hot stage. Actually, the morphol...Melting recrystallization processes of melt sheared films of polypropylene（S28C） fractions have been investigated in situ by polarized optical microscope equipped with CCD camera and hot stage. Actually, the morphological developments in the melting recrystallization are partially reappearance of oriented crystallization processes during melt shearing the fractions, which is due to a memory effect of oriented structure of polymer. For low molecular weight fraction, only incomplete spherulites with some orientation along shear direction are observed in the melting recrystallization processes of the sheared films. For middle molecular weight fractions, extended chain fiber crystals（or bands） are formed first at higher temperatures, and the bands can act as self nuclei（ i.e ., row nuclei）, resulting in epitaxial growth of chain folded lamellae（or fibril）, i.e ., the formation of cylindrites, with further decrease of the crystallization temperature. For high molecular weight fraction, however, it is not possible to shear the melt film because of its high melt viscosity. When the low molecular weight fraction in which no fiber crystals or cylindrites are observed, are mixed with small amount（about 1%\2%） of the high molecular weight fraction, quite large number of cylindrites are formed during the melting recrystallization process of its sheared film, which implies that the component of high molecular weight plays an important role in the formation of cylindrites during the shear process of polypropylene.展开更多
目的研究大黄在防治重度急性有机磷中毒(AOPP)引起全身炎症反应综合征(SRIS)、胃肠功能障碍、多器官功能障碍综合征(MODS)方面的效果。方法将100例受试对象按照随机对照原则分为大黄组50例和甘露醇组50例。2组均采用留置胃管反复洗胃,...目的研究大黄在防治重度急性有机磷中毒(AOPP)引起全身炎症反应综合征(SRIS)、胃肠功能障碍、多器官功能障碍综合征(MODS)方面的效果。方法将100例受试对象按照随机对照原则分为大黄组50例和甘露醇组50例。2组均采用留置胃管反复洗胃,长托宁、氯解磷定肌注,综合对症治疗。在此基础上,大黄组予生大黄粉12.0 g胃管注入,每8 h 1次;甘露醇组予甘露醇250 mL胃管注入,每12 h 1次。均连续使用5 d。统计2组患者入院时及病程的1,2,3,4,5 d处于胃肠功能障碍、MODS状态的病例数以及血C反应蛋白(CRP)的浓度。结果在病程的2,3,4,5 d,大黄组血CRP浓度的降幅较甘露醇组显著(P均<0.05);胃肠功能障碍的改善快于甘露醇组,在病程的1,2,3 d 2组比较有显著性差异(P均<0.05);第2,3,4,5天,大黄组MODS发生例数减少速度快于甘露醇组(P均<0.05)。结论大黄治疗AOPP患者能促进胃肠功能恢复,抑制CRP的释放,提升MODS防治效果。展开更多
文摘Melting recrystallization processes of melt sheared films of polypropylene（S28C） fractions have been investigated in situ by polarized optical microscope equipped with CCD camera and hot stage. Actually, the morphological developments in the melting recrystallization are partially reappearance of oriented crystallization processes during melt shearing the fractions, which is due to a memory effect of oriented structure of polymer. For low molecular weight fraction, only incomplete spherulites with some orientation along shear direction are observed in the melting recrystallization processes of the sheared films. For middle molecular weight fractions, extended chain fiber crystals（or bands） are formed first at higher temperatures, and the bands can act as self nuclei（ i.e ., row nuclei）, resulting in epitaxial growth of chain folded lamellae（or fibril）, i.e ., the formation of cylindrites, with further decrease of the crystallization temperature. For high molecular weight fraction, however, it is not possible to shear the melt film because of its high melt viscosity. When the low molecular weight fraction in which no fiber crystals or cylindrites are observed, are mixed with small amount（about 1%\2%） of the high molecular weight fraction, quite large number of cylindrites are formed during the melting recrystallization process of its sheared film, which implies that the component of high molecular weight plays an important role in the formation of cylindrites during the shear process of polypropylene.
文摘目的研究大黄在防治重度急性有机磷中毒(AOPP)引起全身炎症反应综合征(SRIS)、胃肠功能障碍、多器官功能障碍综合征(MODS)方面的效果。方法将100例受试对象按照随机对照原则分为大黄组50例和甘露醇组50例。2组均采用留置胃管反复洗胃,长托宁、氯解磷定肌注,综合对症治疗。在此基础上,大黄组予生大黄粉12.0 g胃管注入,每8 h 1次;甘露醇组予甘露醇250 mL胃管注入,每12 h 1次。均连续使用5 d。统计2组患者入院时及病程的1,2,3,4,5 d处于胃肠功能障碍、MODS状态的病例数以及血C反应蛋白(CRP)的浓度。结果在病程的2,3,4,5 d,大黄组血CRP浓度的降幅较甘露醇组显著(P均<0.05);胃肠功能障碍的改善快于甘露醇组,在病程的1,2,3 d 2组比较有显著性差异(P均<0.05);第2,3,4,5天,大黄组MODS发生例数减少速度快于甘露醇组(P均<0.05)。结论大黄治疗AOPP患者能促进胃肠功能恢复,抑制CRP的释放,提升MODS防治效果。
