在延伸流中观察聚合物构造歇斯底里
Charles M Schroeder1, Hazen P Babcock, Eric S G Shaqfeh
1Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.
Science (New York, N.Y.)
|September 13, 2003
概括
高度可扩展的DNA分子在扩展流中表现出构造歇斯底里,由于水力动力学力量而持续存在. 这一发现影响了对聚合物流动应力和应力-应变关系的理解.
科学领域:
- 聚合物物理 聚合物物理
- 生物物理学的生物物理.
- 流体动力学 流体动力学
背景情况:
- 了解聚合物在延伸流中的行为对于各种应用至关重要.
- 由于它们的高度可扩展性,DNA分子可以作为优秀的模型系统.
- 聚合物在流动下的形状变化会影响散装性质.
研究的目的:
- 在平面延伸流中可视化和分析高度可扩展的DNA分子的结构动态.
- 为了研究在稀释的聚合物溶液中构造歇斯底里现象.
- 阐明水力动力学力和自由能量景观在聚合物构成过渡中的作用.
主要方法:
- 光显微镜被用于可视化单个大肠杆菌的DNA分子.
- 实验是在受控平面延伸流下在稀释溶液中进行的.
- 计算机模拟被用来计算聚合物构成的自由能量景观.
主要成果:
- DNA分子采用了卷状或高度延伸的形状.
- 一个狭窄的流强度范围诱导了依赖于变形历史的变形歇斯底里.
- 这种歇斯底里持续了很长一段时间,比聚合物放松时间更长.
- 模拟显示了在线圈伸展过渡附近的两个自由能量最小值.
结论:
- 在DNA中,构造歇斯底里是由构造依赖的水力动力学力驱动的.
- 观察到的歇斯底里循环可以影响散溶液应力.
- 这些发现有助于开发稀释聚合物流的应力-应变关系.
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