We device a relaxed lattice model （RLM） to study the mechanism of glass transition, which unifies the cage- effects from particle-particle interaction and entropy. By analyzing entropy in RLM with considering the in...We device a relaxed lattice model （RLM） to study the mechanism of glass transition, which unifies the cage- effects from particle-particle interaction and entropy. By analyzing entropy in RLM with considering the influence of interactions on equilibrium, we demonstrate that glass transition is a second-order phase transition. For a perfect one- dimensional linked particle system like linear polymer under normal pressure, the free volume at glass transition is rigorously deduced out to be 2.6%, which provides a theoretical basis for the iso-free volume of 2.5% given by Willian, Landel and Ferry （WLF） equation. Extending to system with dead particles linked with higher dimensions like branched or cross-linked chains under positive or negative pressure, free volume at glass transition is varied, based on which we construct a phase diagram of glass transition in the space of free volume-dead particle-pressure. This demonstrates that free volume is not the single parameter determining glass transition, while either dead particles like cross-linked points or external force fields like pressure can vary free volume at the glass transition.展开更多
目的 8 异前列腺素F2α(8 iso PGF2α)是一种敏感、特异性反映缺血 再灌注后氧自由基增加的生 化指标。抗氧化剂N 乙酰半胱氨酸(NAC)具有清除氧自由基的作用。本研究旨在分析实验性心肌缺血大鼠血浆 与心肌8 iso PGF2α相关性以及...目的 8 异前列腺素F2α(8 iso PGF2α)是一种敏感、特异性反映缺血 再灌注后氧自由基增加的生 化指标。抗氧化剂N 乙酰半胱氨酸(NAC)具有清除氧自由基的作用。本研究旨在分析实验性心肌缺血大鼠血浆 与心肌8 iso PGF2α相关性以及NAC的治疗效果,探讨血浆8 iso PGF2α反映心肌氧自由基损伤程度的可能性和 NAC的干预效果。方法 45只雄性成年Wistar大鼠随机分为3组(每组15只):对照组、缺血组和NAC组。缺血 组和NAC组腹腔注射垂体后叶素(20U/kg)制成大鼠急性心肌缺血模型,以心电图上ST段的抬高作为心肌缺血 的指标。对照组仅腹腔注射生理盐水。NAC组缺血前2周开始用NAC(每日0.1g/kg)灌胃,共3周。应用ELISA 方法测定各组大鼠血浆及心肌组织8 iso PGF2α含量。结果 缺血组大鼠的血浆和心肌组织含量分别为(187.1± 45.8)pg/mL和(259.3±47.5)pg/g,明显高于正常对照组(60.4±13.7)pg/mL和(88.6±16.9)pg/g (P<0.01);NAC组的血浆和心肌组织8 iso PGF2α含量为(88.2±16.4)pg/mL和(109.4±24.7)pg/g明显低于 缺血组(P<0.01)。血浆与心肌8 iso PGF2α水平相关(r=0.856,P<0.01)。与正常组比较,缺血组的心电图 ST段明显抬高(心肌缺血45min时抬高最为明显,达0.34±0.05mV)(P<0.05);展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51325301 and 51633009)
文摘We device a relaxed lattice model （RLM） to study the mechanism of glass transition, which unifies the cage- effects from particle-particle interaction and entropy. By analyzing entropy in RLM with considering the influence of interactions on equilibrium, we demonstrate that glass transition is a second-order phase transition. For a perfect one- dimensional linked particle system like linear polymer under normal pressure, the free volume at glass transition is rigorously deduced out to be 2.6%, which provides a theoretical basis for the iso-free volume of 2.5% given by Willian, Landel and Ferry （WLF） equation. Extending to system with dead particles linked with higher dimensions like branched or cross-linked chains under positive or negative pressure, free volume at glass transition is varied, based on which we construct a phase diagram of glass transition in the space of free volume-dead particle-pressure. This demonstrates that free volume is not the single parameter determining glass transition, while either dead particles like cross-linked points or external force fields like pressure can vary free volume at the glass transition.
文摘目的 8 异前列腺素F2α(8 iso PGF2α)是一种敏感、特异性反映缺血 再灌注后氧自由基增加的生 化指标。抗氧化剂N 乙酰半胱氨酸(NAC)具有清除氧自由基的作用。本研究旨在分析实验性心肌缺血大鼠血浆 与心肌8 iso PGF2α相关性以及NAC的治疗效果,探讨血浆8 iso PGF2α反映心肌氧自由基损伤程度的可能性和 NAC的干预效果。方法 45只雄性成年Wistar大鼠随机分为3组(每组15只):对照组、缺血组和NAC组。缺血 组和NAC组腹腔注射垂体后叶素(20U/kg)制成大鼠急性心肌缺血模型,以心电图上ST段的抬高作为心肌缺血 的指标。对照组仅腹腔注射生理盐水。NAC组缺血前2周开始用NAC(每日0.1g/kg)灌胃,共3周。应用ELISA 方法测定各组大鼠血浆及心肌组织8 iso PGF2α含量。结果 缺血组大鼠的血浆和心肌组织含量分别为(187.1± 45.8)pg/mL和(259.3±47.5)pg/g,明显高于正常对照组(60.4±13.7)pg/mL和(88.6±16.9)pg/g (P<0.01);NAC组的血浆和心肌组织8 iso PGF2α含量为(88.2±16.4)pg/mL和(109.4±24.7)pg/g明显低于 缺血组(P<0.01)。血浆与心肌8 iso PGF2α水平相关(r=0.856,P<0.01)。与正常组比较,缺血组的心电图 ST段明显抬高(心肌缺血45min时抬高最为明显,达0.34±0.05mV)(P<0.05);
