RII Track-4:NSF: Unveiling the structure and thermodynamic stability of pre-nucleation clusters and their role in multistep nucleation

成核影响后续的结晶过程，进而影响我们的日常生活。然而，由于表征有限，其机制仍然知之甚少。研究的目的是确定在盐溶液成核的早期阶段发生了什么。拟议的工作将克服目前的障碍，使用创新的实验设备，使奖学金。该项目的研究结果将进一步加深目前对成核早期阶段的认识，从而更好地理解盐溶液的成核机制。该奖学金项目将在爱荷华州立大学、爱荷华大学、艾姆斯实验室和橡树岭国家实验室之间开展新的多学科合作。一名博士生将获得分子动力学模拟的技能并获得广泛的实践经验。来自西班牙裔专业工程师协会（SHPE）的两名本科生将加入该项目，并在SHPE全国大会上展示他们的工作。爱荷华州立大学现有的三个外展项目将与K-12学生、教师和家长分享奖学金项目。越来越多的材料，包括蛋白质、电解质溶液、生物矿物和胶体，已经被观察到在成核之前以多步形成的预成核团簇（pnc）成核。很明显，pnc在多步成核（MSN）中起着至关重要的作用，但它们的性质却知之甚少。提出的研究的基本原理是，对MSN的机制理解可能为开发控制所需晶体相的成核和生长的方法提供新的机会。因此，该项目旨在确定pnc的结构、热力学稳定性以及在NaCl水溶液中的作用。PI团队将通过将PI团队开发的溶液静电悬浮器（SEL）与橡树岭国家实验室的中子散射相结合，克服目前的实验障碍。该项目的长期目标是开发一个预测框架，以预测和控制各种水溶液中的MSN。本研究将有助于进一步阐明微球在电解质溶液中的作用机理，并为更好地理解微球在其他材料体系中的作用提供更深入的见解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nucleation influences the subsequent crystallization process which impacts our daily life. However, its mechanism remains poorly understood due to limited characterization. The purpose of the research is to identify what occurs at the early stage of nucleation of salt solutions. The proposed work will overcome the current barriers using innovative experimental apparatus enabled by the fellowship. The results of this project will advance the current knowledge on what occurs in the early stage of nucleation, which will lead to a better understanding of the nucleation mechanism of salt solutions. The fellowship project will result in new multidisciplinary collaborations among Iowa State University, the University of Iowa, Ames Laboratory, and Oak Ridge National Laboratory. One doctoral student will acquire skills in molecular dynamics simulation and gain extensive hands-on experience. Two undergraduate students from the Society of Hispanic Professional Engineers (SHPE) will join the project and present their work at the SHPE National Convention. Three existing outreach programs at Iowa State University will be leveraged to share the fellowship project with K-12 students, teachers, and parents. A growing number of materials, including proteins, electrolyte solutions, biominerals, and colloids, have been observed to nucleate in multistep forming pre-nucleation clusters (PNCs) prior to nucleation. It is apparent that PNCs play a critically important role in multistep nucleation (MSN), yet their nature is poorly understood. The rationale for the proposed research is that a mechanistic understanding of MSN is likely to provide new opportunities to develop a method to control the nucleation and growth of desired crystal phases. For this reason, the project aims to identify the structure, thermodynamic stability, and role of PNCs in an aqueous NaCl solution. The PI team will overcome the current experimental obstacles by integrating the solution electrostatic levitator (SEL) developed by the PI team with neutron scattering at Oak Ridge National Laboratory. The long-term goal of the project is to develop a predictive framework to anticipate and control the MSN in various aqueous solutions. The proposed research will lead to a vertical-step advancement towards elucidating the mechanism of MSN in electrolyte solutions and would give deeper insights to better understand the MSN in other material systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.