International Research Fellowship Program: Shear-perturbed Polymer Structure and Dynamics through NMR Spectroscopy and Rheo-NMR

国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持Jennifer R. Brown博士与新西兰惠灵顿大学Paul Callaghan博士开展为期18个月的研究。核磁共振波谱（NMR）与流变核磁共振（Rheo-NMR）相结合，被用于研究聚合物分子的有序性和力学变形的动力学响应。核磁共振技术具有独特的能力，通过空间分辨率将宏观材料响应与微观分子现象通过光谱技术联系起来。由于生物、食品和材料加工、石油开采和生物技术应用中有许多复杂的流体，机械响应的分子基础最近引起了人们的兴趣。由于剪切细胞包含在核磁共振波谱仪中，并且样品可以在运动时进行研究，因此，使用流变核磁共振为研究此类系统中的分子动力学提供了独特的视角。采用高分辨率窄间隙圆柱形库埃特剪切单元，具有足够高的剪切速率，可以中断氢键。对于相关的碳水化合物透明质酸，剪切对构象的影响已被13C核磁共振证实，这强烈表明在其他相关多糖中也可以观察到类似的影响，并鼓励了流变核磁共振和光谱在研究具有预先分配光谱的蛋白质（如胰岛素）方面的潜力。这项研究剪切干扰蛋白质和多糖与核磁共振波谱技术试图确定负责分子间相互作用及其相关的反应速率的位点。蛋白质分子动力学和结构的核磁共振研究有可能改善现代聚合物材料的设计和加工，例如创造具有更好质地的食物或更好地了解生物学上重要的流体特性。由于蛋白质结构与功能有关，因此了解流变对结构的影响可能涉及从生物学到化学和材料科学的各个领域。因此，拟议的研究具有高度的跨学科性质，这增加了跨领域的合作和交流。

0753559BrownThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support an eighteen month research fellowship by Dr. Jennifer R. Brown to work with Dr. Paul Callaghan at the University of Wellington in New Zealand.Nuclear Magnetic Resonance (NMR) spectroscopy, in combination with Rheo-NMR, is being used to study polymer molecular order and dynamics in response to mechanical deformation. NMR techniques have the unique ability to connect macroscopic material responses through spatial resolution to microscale molecular phenomena via spectroscopic techniques. The molecular basis for the mechanical response has been of recent interest since there are many complex fluids in biology, food and material processing, oil recovery and biotechnology applications. The use of Rheo-NMR offers a unique perspective in the investigation of the molecular dynamics in such systems, since the shear cell is contained within the NMR spectrometer and the sample may be studied while in motion. A high resolution narrow gap cylindrical Couette shear cell is used with the capacity for high enough shear rates that hydrogen bonds should be interrupted. For the associating carbohydrate hyaluronan, the influence of shear on conformation has been proven using 13C NMR, which strongly suggests that similar effects can be observed in other associating polysaccharides, and encourages the potential of Rheo-NMR and spectroscopy in investigating proteins with a pre-assigned spectra, such as insulin. This study of shear-perturbed proteins and polysaccharides with NMR spectroscopic techniques attempts to identify the sites responsible for inter-molecular interactions and their associated reaction rates. NMR studies of protein molecular dynamics and structure have the potential to improve the design and processing of modern polymeric materials, such as creating food with better texture or to better understand biologically important fluid properties. Since protein structure is related to function, the possible scientific impacts of understanding the rheological effect on structure spans fields ranging from biology to chemistry and materials science. The proposed research is therefore of a highly inter-disciplinary nature, which increases collaboration and communication across fields.