rheo-NMR system for crystallization studies

本申请是资助现有脉冲核磁共振设备（pNMR）的修改，以便能够对结晶脂质系统进行流变核磁共振实验。我们需要它来模拟剪切流对受控多组分脂质系统结晶的影响。结晶动力学研究的主要参数是固体分数（称为固体脂肪含量，SFC）随时间和温度的增加。被加工材料的流变特性随着结晶过程的变化而变化。在这些材料中获得SFC的唯一直接非破坏性方法是pNMR，而流变特性需要使用能够测量剪切时施加在样品上的应力的流变仪。变化是连续的，而且相对较快，因此人工数据采集是不可靠的。由于使用单独的仪器会导致不同的温度条件和界面条件，因此需要组合测量，从而排除了所生成数据的真正组合。这些综合信息将使我们能够检验为这些系统制定的关于剪切效应的假设，如成核和生长的加速、多晶转变、多晶路径的变化和各向异性结构的形成。我们的基本科学见解和模型将改进目前以经验为基础的工艺和设备设计。基础研究将通过准备由几个仍然可以模拟自然系统的单个组件组成的受控系统来进行。因此，这些系统的多组分性质在剪切作用下的影响将得到更好的理解。应用项目将包括包含数千个组成部分的常见天然材料。这种独特的仪器将允许研究生在几个基本学科，如物理化学，流变学，输运现象和软材料科学训练。

This application is to fund the modification of an existing pulsed nuclear magnetic resonance equipment (pNMR) to be able to perform Rheo-NMR experiments on crystallizing lipid systems. We need this to model the effects of shear flow on crystallization of controlled multicomponent lipid systems. The main parameter in the study of kinetics of crystallization is the increase in solid fraction (known as solid fat content, SFC) as a function of time and temperature. The rheological characteristics of the processed material change as the crystallization progresses under flow.  The only direct non-destructive method to obtain SFC in these materials is pNMR, whereas the rheological characteristics require using a rheometer capable of measuring the stress applied to the sample as it is sheared. The changes happen continuously and relatively fast, therefore manual data acquisition is not reliable. The combined measurements are needed because using separate instruments would result in different temperature conditions and interfacial conditions, thus precluding real combination of the data generated. The combined information will allow us to test hypotheses formulated for these systems regarding effects of shear such as acceleration of nucleation and growth, polymorphic transformations, variation of polymorphism paths, and formation of anisotropic structures. Our fundamental scientific insights and models will improve the design of processes and equipment, currently done rather empirically. Fundamental studies will be carried by preparing controlled systems made up of a few single components that can still mimic natural systems. The impact of the multicomponent nature of these systems under shear will therefore be better understood. Applied projects will include common natural materials which contain thousands of components. This unique instrument will allow graduate students to be trained in several essential disciplines such as physical chemistry, rheology, transport phenomena, and soft materials science.