Integrated Experimental and Simulation Studies of the Structure and Dissolution Mechanism of Bioactive Glasses

ID：MPS/DMR/BMAT（7623）0907593 主要研究者：杜金城 ORG：北德克萨斯大学生物活性玻璃的结构和溶解机理的综合实验和模拟研究智力优势：将原子模拟和实验（X射线和中子衍射）研究相结合，以获得无机生物活性玻璃的精细玻璃结构模型;这些模型对于更好地理解这些材料的生物活性至关重要。 （生物活性在此表示这些材料与骨结合并最终促进骨生长和发育的能力，包括成骨细胞分化、增殖、活力和矿化。 固有的复杂性和缺乏长程有序限制了我们对多组分玻璃结构的理解，这在生物医学应用等领域非常重要。通过创新方法的发展以及实验和建模研究的整合，该项目解决了两个具有科学挑战性的问题：复杂多组分氧化物玻璃的结构和这些玻璃在水环境中的溶解机制。经典分子动力学和蒙特卡罗模拟等计算机模拟方法已经产生了大量关于玻璃结构的信息，但结果严重依赖于经验势模型的质量，并且通常需要对实验结果进行验证。另一方面，诸如中子和X射线衍射、EXAFS以及红外和拉曼光谱等实验方法可以探测玻璃结构的某些方面，但通常限于平均短程结构或相互重叠的结构信息。所提出的新方法的新奇在于将经典或从头算分子动力学模拟与基于散射数据的反向蒙特卡罗算法相结合，以研究玻璃材料的结构，这将生成具有更精细的结构模型。基于这些结构模型，生物活性玻璃的溶解将使用动力学Monte Carlo模拟与从头算DFT计算的反应能垒和反应途径的输入进行研究。 所获得的结构模型和溶解机制可以指导用于生物医学应用的新玻璃组合物和工艺的更合理和系统的设计。该项目涉及研究生和本科生的强化培训，以掌握将联合收割机多尺度材料建模与最先进的材料表征技术相结合的技能，从而为学生未来解决具有挑战性的材料问题的职业生涯做好准备。精制生物活性玻璃在骨修复和修复中的潜在应用代表了一个竞技场，在这个领域中，这项研究可能具有重要的更广泛的意义。冲击 PI描述了一个深思熟虑的承诺，了解学生如何学习，并提供各种实践经验，实现这一理解。 他开发了一门新的计算材料科学课程，该课程基于一系列模块，旨在培养学生对材料现象及其潜在机制和实验方法的理解。 他使用多媒体通过三维可视化和操作来解释晶体结构，使用原子尺度模拟的电影来说明晶体位错，并通过过渡态理论和能量势垒计算来传达扩散过程。 PI让学生参与高级课程的另一个重要方式是使用基于文学的教学。 在这里，他专注于一组经典和开创性的论文，通过课堂讨论，家庭作业和考试来剖析和消化它们。 这教学生如何有效地使用文献，成为合格的研究人员。 PI还涉及他的研究实验室的本科生，准备生物活性玻璃样品的学生将有机会访问阿贡参加散射研究。 由PI为达拉斯-沃斯堡地区高中教师组织的材料日向教师介绍了校园内最先进的材料处理、表征和建模设施。 他还在沃斯堡学区与拉丁裔和美洲土著学生进行外联。 他目前正在指导科学项目的学生在得克萨斯州高级数学和科学计划，一个为期两年的住宅早期大学入学计划，为选定的高中学生。

ID: MPS/DMR/BMAT(7623) 0907593 PI: Du, Jincheng ORG: University of North TexasTitle: Integrated Experimental and Simulation Studies of the Structure and Dissolution Mechanism of Bioactive GlassesINTELLECTUAL MERIT: Combined atomistic simulations and experimental (X-ray and neutron diffraction) studies will be carried out to obtain refined glass structure models of inorganic bioactive glasses; such models are critical to a better understanding of the bioactivities of these materials. (Bioactivity here denotes the ability of these materials to bond to bone and ultimately to promote bone growth and development, including osteoblast differentiation, proliferation, viability, and mineralization.) The inherent complexity and the lack of long-range order limit our understanding of the structure of multi-component glasses that are important in fields such as biomedical applications. Through development of innovative methodology and integration of experimental and modeling studies, this project attacks two scientifically challenging problems: the structure of the complex multi-component oxide glasses and the dissolution mechanism of these glasses in an aqueous environment. Computer simulation methods such as classical molecular dynamics and Monte Carlo simulations have generated a wealth of information about glass structure, but the results rely heavily on the quality of empirical potential models and validation on experimental results is usually needed. On the other hand, experimental methods such as neutron and X-ray diffraction, EXAFS, and infrared and Raman spectroscopy can probe certain aspects of the structure of glasses but are often limited to averaged short-range structures or mutually overlapping structural information. The novelty of the proposed new method lies in integrating classical or ab initio molecular dynamics simulations with the reverse Monte Carlo algorithm based on scattering data in studying the structure of glass materials, which will generate structural models that have more refined short- and medium-range structures for complex multi-component systems such as bioactive glasses. Based on these structural models, dissolution of bioactive glasses will be studied using kinetic Monte Carlo simulations with input of reaction energy barriers and reaction pathways from ab initio DFT calculations. The structural models and dissolution mechanisms obtained can guide more rational and systematic design of new glass compositions and processes for biomedical applications. This project involves intensive training of graduate and undergraduate students to master skills that combine multiscale materials modeling with state-of-the-art material characterization techniques, and thus prepares students for future careers that involve solving challenging materials problems.BROADER IMPACTS: Potential applications of refined bioactive glasses in restoration and repair of bone represent an arena in which this research may have an important broader impact. The PI describes a thoughtful commitment to understanding how students learn and to providing the kinds of hands-on experiences that implement this understanding. He has developed a new course in Computational Materials Science based on a series of modules that develop students' understanding of materials phenomena and the underlying mechanisms and experimental methods. He uses multimedia to explain crystal structures through three-dimensional visualization and manipulation, to illustrate crystal dislocations using movies of atomic scale simulations, and to convey the diffusion process through transition state theory and energy barrier calculations. Another important way the PI involves students in advanced courses is to use literature based instruction. Here he focuses on a group of classical and seminal papers, dissecting them and digesting them through class discussions, homework, and exams. This teaches the students how to use the literature effectively to become qualified researchers. The PI also involves undergraduates in his research lab, and the students who prepare the bioactive glass samples will have the opportunity to visit Argonne to participate in the scattering studies. A Materials Day organized by the PI for Dallas-Fort Worth area high school teachers introduces the teachers to state of the art materials processing, characterization, and modeling facilities available on his campus. He also conducts outreach to Latino and Native American students in the Fort Worth School District. He is currently guiding science projects for students in the Texas Advanced Math and Science program, a two year residential early college entrance program for selected high school students.