Understanding functional properties of biological and smart materials

核磁共振是了解与功能特性有关的材料纳米级特征的有力工具。在生物组织中，了解产生成像对比度的机制对于临床应用成像方法至关重要。在新的工程材料类别中，了解光学、机械和电学特性的机理对于将这些新材料应用于现实世界的问题至关重要。这项建议描述了两个领域的研究：生物组织和工程“智能”材料，统一的愿景是深入理解结构、功能和性能之间的关系，以使应用成为可能。在脑组织中，隔离神经轴突的髓鞘在神经冲动的传递中起着关键作用。非侵入性测量髓鞘的丰度和状态是一个巨大的挑战。令人惊讶的是，在一些被广泛使用的测量髓鞘的磁共振成像(MRI)技术中，产生对比的机制还知之甚少。我们的目标是：1)探索髓鞘中核自旋系统的物理细节，2)将方法学从固态核磁共振技术应用于体内成像的限制，3)开发新的对比机制以更好地表征髓鞘的丰度和健康，4)了解MRI脉冲序列对可观察到的核磁共振/核磁共振信号的间接影响，这些信号源于大脑中“看不见的”非水成分。在工程材料方面，我们将与几个不同的研究小组合作，解释他们制造的材料的新特性，并指导他们的开发和应用。这些材料包括：i)新型热固性聚合物，为制备性能可调的真正可再结晶的塑料提供了一条有希望的途径；ii)用于双向人机接口的离子导电聚合物膜；以及iii)新型氢键液晶，具有独特的性能，如光学开关和在很大温度范围内稳定的备受追捧的“蓝色相”。对于这些系统中的每一个，我们将结合核磁共振测量和新的原位机械、电或光刺激，以揭示导致其有用特性的微观结构和过程。这些研究对指导材料的发展和应用具有重要意义。这项研究的影响将不仅体现在单个项目的领域，创新的混合核磁共振方法将为分子机制提供无与伦比的新见解，而且还将从结果的合成中感受到；通过学习这些材料和组织的共同主题和独特差异，我们将拓宽和加深我们的理解，使材料快速进步，并使医学成像的对比度方法更好。

Nuclear magnetic resonance is a powerful tool for understanding the nanoscale features of materials that are responsible for functional properties. In biological tissues, understanding the mechanisms that give rise to imaging contrast is crucial for applying imaging methods clinically. In new classes of engineered materials, understanding the mechanisms of optical, mechanical, and electrical properties is essential for applying these new materials to real-world problems. This proposal describes research in two areas: biological tissues, and engineered `smart' materials, unified by the vision of developing deep understanding of the relationships between structure, function, and properties to enable applications. In brain tissue, the myelin sheath that insulates nerve axons plays a key role in the transmission of nerve impulses. Non-invasive measurement of the abundance and condition of the myelin is a grand challenge. Surprisingly, the mechanisms that give rise to contrast in some widely used magnetic resonance imaging (MRI) techniques to measure myelin are poorly understood. Our objectives are to: 1) explore the details of the physics of the nuclear spin systems in myelin, 2) adapt methodology from solid-state NMR techniques to the constraints of in vivo imaging, 3) develop new contrast mechanisms to better characterize myelin abundance and health, 4) understand the indirect effects that MRI pulse sequences have on the observable NMR/MRI signals, arising from the "invisible" non-aqueous components in brain. In engineered materials, we will work with several different research groups in order to explain the novel properties of the materials they make, and guide their development and application. These materials include: i) a new class of thermoset polymers that offer a promising path to truly recylable plastics with tunable properties, ii) ionic conducting polymer membranes that will be useful for bidirectional human-computer interfaces, and iii) a new class of hydrogen-bonded liquid crystals that show unique properties such as optical switching and a highly-sought after "blue-phase" that is stable over a large temperature range. For each of these systems, we will combine NMR measurements with novel in situ mechanical, electrical, or optical stimulation in order to reveal the microscopic structures and processes responsible for their useful properties. These studies are essential to guide the development of the materials and their applications. The impact of this research will be felt not only within the fields of the individual projects, where the innovative hybrid NMR methods will provide unparalleled new insights into molecular mechanisms, but also from the synthesis of the results; by learning from the common themes and unique differences of these materials and tissues, we will both broaden and deepen our understanding, enabling rapid advancement of materials and better contrast methods for medical imaging.