NIRT: Complex Fluids Confined at the Nanoscale

该提案是响应纳米尺度科学与工程计划，NSF 03-043，类别NIRT而收到的。这个理论奖是由材料研究部和化学部支持的。在极端约束下的流体表现出新的动力学性质，而不是体行为的简单扩展。直观地说，当约束尺寸与流体中协同运动的长度尺度相当时，就会出现极端约束，通常在纳米范围内。了解这些自然长度尺度和外部限制之间的相互作用是这项研究的目标。限制可以由外部几何形状施加，例如在薄聚合物薄膜或多孔介质中的液体中，但也可以由其他物体引起的“拥挤”引起，如在细胞内部自然发生的或在玻璃化转变附近的过冷液体中。在所有这些系统中，时间演化涉及具有内部自由度的扩展物体的运动。将构建这些对象的有效模型；介于分子动力学模拟的微观尺度和流体动力学描述的宏观尺度之间的一种尺度。这样的框架提供了一个有用的接口理论和实验之间的使用实际空间探测器研究纳米尺度的运动。结合这些实验，将构建一个与长度尺度和时间尺度相关的框架，并用于理解约束对动力学的影响。数值模拟将作为构建有效动力学理论的垫脚石。这些技术将在晶格模型的背景下发展，然后扩展到连续体模型。这项研究将为一系列生物学问题提供建模工具，包括细胞流变学、拥挤细胞环境中大分子的运动、细胞骨架动力学等。在技术方面，目前人们正在努力将各种生物化学技术小型化，并将其集成到单个芯片上，用于纯化、检测和分类生物分子。这些技术将本研究解决的一个核心问题摆在了前台和中心：极端约束如何影响大分子的运动？理论工具，如简单的模型和数值模拟，结合良好控制系统的实验，将有助于这些“芯片实验室”技术的合理设计。这些活动的一个关键方面是在波士顿地区建立一个物理学家、化学家和生物学家的社区，他们因对受限系统动力学的兴趣而团结在一起。管理PI发起了一次两年一次的会议，聚集了波士顿地区对玻璃现象感兴趣的学生，博士后助理和教职员工，广泛解释。事实证明，这些活动对于不同群体之间的思想交流和让学生接触到各种各样的思想是非常宝贵的。目前的项目建立在这个活动的基础上：(1)描述了一个针对波士顿地区四年制女子学院本科生的新的夏季研究项目；(2)扩大了两年一次的会议的范围，包括迷你课程，这将是对慢动力学跨学科领域研究生教育的一个有价值的补充。该提案是根据纳米科学与工程计划（NSF 03-043， NIRT类别）收到的。这个理论奖是由材料研究部和化学部支持的。在极端约束下的流体表现出新的动力学性质，而不是体行为的简单扩展。直观地说，当约束尺寸与流体中协同运动的长度尺度相当时，就会出现极端约束，通常在纳米范围内。了解这些自然长度尺度和外部限制之间的相互作用是这项研究的目标。限制可以由外部几何形状施加，例如在薄聚合物薄膜或多孔介质中的液体中，但也可以由其他物体引起的“拥挤”引起，如在细胞内部自然发生的或在玻璃化转变附近的过冷液体中。在所有这些系统中，时间演化涉及具有内部自由度的扩展物体的运动。将构建这些对象的有效模型；介于分子动力学模拟的微观尺度和流体动力学描述的宏观尺度之间的一种尺度。这样的框架提供了一个有用的接口理论和实验之间的使用实际空间探测器研究纳米尺度的运动。结合这些实验，将构建一个与长度尺度和时间尺度相关的框架，并用于理解约束对动力学的影响。数值模拟将作为构建有效动力学理论的垫脚石。这些技术将在晶格模型的背景下发展，然后扩展到连续体模型。这项研究将为一系列生物学问题提供建模工具，包括细胞流变学、拥挤细胞环境中大分子的运动、细胞骨架动力学等。在技术方面，目前人们正在努力将各种生物化学技术小型化，并将其集成到单个芯片上，用于纯化、检测和分类生物分子。这些技术将本研究解决的一个核心问题摆在了前台和中心：极端约束如何影响大分子的运动？理论工具，如简单的模型和数值模拟，结合良好控制系统的实验，将有助于这些“芯片实验室”技术的合理设计。这些活动的一个关键方面是在波士顿地区建立一个物理学家、化学家和生物学家的社区，他们因对受限系统动力学的兴趣而团结在一起。管理PI发起了一次两年一次的会议，聚集了波士顿地区对玻璃现象感兴趣的学生，博士后助理和教职员工，广泛解释。事实证明，这些活动对于不同群体之间的思想交流和让学生接触到各种各样的思想是非常宝贵的。目前的项目建立在这一活动的基础上：(1)描述了一个针对波士顿地区四年制女子学院本科生的新的夏季研究项目；(2)扩大了两年一次的会议的范围，包括迷你课程，这将是对慢动力学跨学科领域研究生教育的一个有价值的补充

This proposal was received in response to Nanoscale Science and Engineering initiative, NSF 03-043, category NIRT. This theoretical award is supported by the Division of Materials Research and the Chemistry Division. Fluids under extreme confinement exhibit novel dynamical properties which are not simple extensions of the bulk behavior. Intuitively, extreme confinement sets in when the confining dimensions become comparable to the length scales associated with the cooperative motion in the fluids which are typically in the nanometer domain. Understanding the interplay between these natural length scales and the external constraints is the goal of the research outlined in this grant. Constraints can be imposed by the external geometry such as in thin polymer films or liquids in porous media, but can also arise from "crowding" due to other objects as occur naturally in the interior of cells or in supercooled liquids near the glass transition. In all of these systems, temporal evolution involves the motion of extended objects which have internal degrees of freedom. Effective models at the scale of these objects will be constructed; a scale intermediate between the microscopic one characteristic of molecular dynamics simulations and the macroscopic scale of hydrodynamic descriptions. Such a framework provides a useful interface between theory and experiments which use real-space probes to study motion at the nanometer scale. In conjunction with such experiments, a framework relating length scales and time scales will be constructed and used to understand the effects of constraints on the dynamics. Numerical simulations will be used as a stepping stone in the construction of effective dynamical theories. The techniques will be developed in the context of lattice models and then extended to continuum models.The research will provide modeling tools for a range of problems in biology that includes rheology of cells, motion of macromolecules in crowded cell environments, dynamics of the cytoskeleton, to mention a few. On the technological side of things, much effort is currently being expended on miniaturizing and integrating various biochemical techniques for purifying, detecting, and sorting biological molecules, on a single chip. These techniques put front and center one of the central questions addressed by this research: How is the motion of macromolecules affected by extreme confinement? Theoretical tools such as simple models and numerical simulations, combined with experimentation on well controlled systems will contribute to the rational design of these "lab on a chip" technologies.A crucial aspect of the activities is building a community of physicists, chemists and biologists in the Boston area, united by their interest in dynamics of constrained systems. The managing PI has initiated a biannual meeting that brings together students, postdoctoral associates and faculty, in the Boston area, interested in glassy phenomena, broadly construed. These have proven invaluable for exchanging ideas between various groups and exposing students to a range of ideas. The current program builds on this activity by (i) describing a new summer research program aimed at undergraduates from the women's four-year colleges in the Boston area and (ii) enlarging the scope of the biannual meetings to include minicourses which will be a valuable addition to graduate education in the interdisciplinary area of slow dynamics.%%%This proposal was received in response to Nanoscale Science and Engineering initiative, NSF 03-043, category NIRT. This theoretical award is supported by the Division of Materials Research and the Chemistry Division. Fluids under extreme confinement exhibit novel dynamical properties which are not simple extensions of the bulk behavior. Intuitively, extreme confinement sets in when the confining dimensions become comparable to the length scales associated with the cooperative motion in the fluids which are typically in the nanometer domain. Understanding the interplay between these natural length scales and the external constraints is the goal of the research outlined in this grant. Constraints can be imposed by the external geometry such as in thin polymer films or liquids in porous media, but can also arise from "crowding" due to other objects as occur naturally in the interior of cells or in supercooled liquids near the glass transition. In all of these systems, temporal evolution involves the motion of extended objects which have internal degrees of freedom. Effective models at the scale of these objects will be constructed; a scale intermediate between the microscopic one characteristic of molecular dynamics simulations and the macroscopic scale of hydrodynamic descriptions. Such a framework provides a useful interface between theory and experiments which use real-space probes to study motion at the nanometer scale. In conjunction with such experiments, a framework relating length scales and time scales will be constructed and used to understand the effects of constraints on the dynamics. Numerical simulations will be used as a stepping stone in the construction of effective dynamical theories. The techniques will be developed in the context of lattice models and then extended to continuum models.The research will provide modeling tools for a range of problems in biology that includes rheology of cells, motion of macromolecules in crowded cell environments, dynamics of the cytoskeleton, to mention a few. On the technological side of things, much effort is currently being expended on miniaturizing and integrating various biochemical techniques for purifying, detecting, and sorting biological molecules, on a single chip. These techniques put front and center one of the central questions addressed by this research: How is the motion of macromolecules affected by extreme confinement? Theoretical tools such as simple models and numerical simulations, combined with experimentation on well controlled systems will contribute to the rational design of these "lab on a chip" technologies.A crucial aspect of the activities is building a community of physicists, chemists and biologists in the Boston area, united by their interest in dynamics of constrained systems. The managing PI has initiated a biannual meeting that brings together students, postdoctoral associates and faculty, in the Boston area, interested in glassy phenomena, broadly construed. These have proven invaluable for exchanging ideas between various groups and exposing students to a range of ideas. The current program builds on this activity by (i) describing a new summer research program aimed at undergraduates from the women's four-year colleges in the Boston area and (ii) enlarging the scope of the biannual meetings to include minicourses which will be a valuable addition to graduate education in the interdisciplinary area of slow dynamics.***