Collaborative research MSPA-ENG: Dynamics of interfacial domains

建议编号：CBET-0730626首席研究员：詹姆斯·C·亚历山大大学/机构：凯斯西储大学。标题：合作研究MSPA-ENG：界面区域的动力学这是与CBET-0730475/肯特和0730630/哈维·马德学院的合作项目。该项目旨在通过将实验与数学和数值分析相结合，定量描述限制在流体/流体界面(朗缪尔层)的分子薄层内的区域动力学。这些层内的运动被限制在表面的平面内，从而在两个维度上。然而，分子构型可以相对于表面自由变化，并且层可以从表面弯曲出来。这样的层呈现出丰富的表面相：气体和液体、液晶和弹性“固体”。过去15年的实验发展使人们对这些阶段有了更清晰的了解。动态过程虽然对表征薄膜的宏观和介观性质是必不可少的，但事实证明，通过实验测量和通过数学分析来定量理解要困难得多。由于控制细胞膜过程的模拟动力学，这些层中的动力学是重要的，而且因为它们是对朗缪尔层的物理化学性质的探测。PI首先描述了他们在流体单层内动力学的新结果，因为结构域向平衡的形状和大小移动。流体动力流动包括朗缪尔层内的运动，但也包括亚流体内的运动，在那里它可能不平行于表面。该小组探索的案例的初步结果表明，结合高质量的实验、详细的表面化学知识、仔细的量纲分析、数学建模、分析技术、智能设计的数值方法和数据分析，可以更深入地理解这些问题的物理原理。通过应用我们的四辊轧机技术，模拟和实验之间的比较远远超出了形状和尺寸上的小扰动，它们将提高线张力测量的准确性和精确度，线张力是动力学和层形态的关键参数。他们还将探索线张力之外的问题，包括静电学和层的可压缩性的影响。为了进行比较，他们将改进实验，包括静电和其他对分析的贡献，并发展数值分析。随着项目的发展，它们将超越流体单层系统，特别是那些涉及弹性固体的系统。智力上的功绩。朗缪尔单分子膜提供了一个可通过实验访问的二维系统，这需要结合仔细的实验、分析和模拟才能有效地进行探测。无论是从实验还是理论上，这些层内的动态过程都很难分析。该项目的主要研究人员已经证明，在合作中，他们可以确定有用的案例，在这些案例中，可以开发出适合数值分析的理论，并将其与相应的实验进行比较。该项目将深化和扩展这一方法。我们已经将线张力的测量精度和准确度提高了一个数量级以上。这将使他们能够直接探索长程力对该参数的影响，并探索温度和组成(包括线活性分子)对线张力的影响，线张力对朗缪尔层及其类似物的形态起着关键作用。更广泛的影响。分子薄层内的动力学对于理解生物膜这样的系统是至关重要的。人们对结构域在生物细胞膜中的功能重要性的认识呈指数级增长：结构域可能会隔离信号传递所需的蛋白质，或者为形状变化提供结构条件。朗缪尔单层为所有这些层提供了一个模型系统。此外，结构域的大小在从纳米到微米的大小范围内都可能是可控的，因此可以通过将朗缪尔层转移到固体衬底上来形成具有不同物理和化学性质的结构域阵列，从而提供比自组装单分子膜更多的控制。这个项目的学生将参与一个跨越三个学科(物理、化学工程和数学)的项目，并体验将不同方法结合起来解决具有基本和实际意义的共同问题的价值。本科生和研究生都包括在这个项目中，该组织也一直致力于让代表不足的群体参与他们的研究。(例如，E.K.Mann团队由一名女性领导。)

Proposal Number: CBET-0730626 Principal Investigator: James C. AlexanderUniversity/Institution: Case Western Reserve Univ.Title: Collaborative Research MSPA-ENG: Dynamics of Interfacial Domains This is a collaborative project with CBET-0730475/ Kent, and 0730630 / Harvey Mudd College.This project aims to quantitatively characterize, by linking experiment to mathematical and numerical analysis, domain dynamics within molecularly thin layers confined at the fluid/fluid interface (Langmuir layers). Motion within these layers is confined to the plane of the surface, and thus in two dimensions. However, molecular configurations can change freely with respect to the surface, and the layer can buckle out of the surface. Such layers present an enormous richness of surface phases: gases and liquids, liquid crystals, and elastic "solids." Experimental developments over the last 15 years have allowed a much clearer understanding of these phases. Dynamic processes, while essential to characterize macro-and mesoscopic properties of the film, prove much more difficult to measure experimentally and understand quantitatively through mathematical analysis. The dynamics in these layers are important due to the analogue dynamics controlling cell membrane processes, but also because they are probes into the physical-chemical nature of the Langmuir layer. The PIs begin by describing their new results for dynamics within fluid monolayers, as the domains move towards equilibrium shape and size. Hydrodynamic flow involves motion within the Langmuir layer, but also within the subfluid, where it may not be parallel to the surface. Preliminary results from the group explore cases that show how combining high-quality experiments, detailed knowledge of surface chemistry, careful dimensional analysis, mathematical modeling, analytical techniques, intelligently-designed numerical methods and data analysis allows a deeper understanding of the physics of these problems. With comparisons between simulations and experiment going far beyond small perturbations in shape and size by application of our 4-roll mill technology, they will improve both accuracy and precision on measurements of the line tension, a critical parameter for both dynamics and layer morphology. They will also explore beyond the line tension, to include the effect of electrostatics and the compressibility of the layer. For this comparison, they will refine the experiment, include electrostatic and other contributions to the analysis, and develop the numerical analysis. As the project develops, they will reach beyond fluid-monolayer systems, in particular to those involving elastic solids that buckle out of the plane. Intellectual Merit. Langmuir monolayers provide an experimentally accessible two-dimensional system, which require a combination of careful experiment, analysis, and simulation to probe effectively. Dynamic processes within these layers have been difficult to analyze, both experimentally and theoretically. The principle investigators in this project have demonstrated that in collaboration, they can identify useful cases in which theories amenable to numerical analysis can be developed and compared to the corresponding experiment. This project will deepen and extend that approach. We have improved both the precision and the accuracy of measurements of the line tension by more than an order of magnitude. This will allow them to directly probe the effect of long-range forces on this parameter, and to explore the effect of temperature and composition, including line-active molecules, on the line tension, which plays a critical role on the morphology within the Langmuir layer and its analogues. Broader Impact. Dynamics within molecularly thin layers is critical for understanding such systems as biological membranes. The recognition of the functional importance of domains in biological cell membranes grows exponentially: domains may sequester proteins needed for signaling or provide structural conditions for shape changes. Langmuir monolayers provide a model system for all such layers. Furthermore, the domain size is potentially controllable over a wide range of sizes from the nano to the micro scales, so that arrays of domains with different physical and chemical properties can be formed by transferring the Langmuir layer to a solid substrate, providing more control than possible with self-assembled monolayers. The students in this project will be involved in a project that cuts across three disciplines (physics, chemical engineering and mathematics), and experience the value of combining different approaches to a common problem with both fundamental and practical implications. Both undergraduate and graduate students are included in this project, and the group also has a history of deep commitment to involving underrepresented groups in their research. (The E.K. Mann group, for example, is headed by a woman.)