The goal of the proposed work is to characterize venous valve tissue mechanics toward combating chronic venous insufficiency via experimental and computational methods.

The PIs propose to acquire a multi-ion-source focused ion beam (FIB)/scanning electron microscope (SEM) equipped with an inductively coupled plasma ion source outfitted with advanced detectors and automation tools. The increased angular intensity of a plasma source is optimal for rapid high-current milling while minimizing specimen damage and ion implantation. This instrument is equipped specifically for statistically meaningful quantitative characterization of material microstructures in three dimensions across dimensions from nm to mm and advanced nanolithography. The coupling of automation tools with the rapid sputtering rates and multiple ion sources unlocks the ability to: 1) study material properties governed by microstructurally rare events, 2) enable hierarchical material property models by providing input microstructures, and 3) create and study three dimensional nanostructures in materials that would be susceptible to ion implantation using conventional Ga ion sources. The location of the instrument within the Research Triangle Nanotechnology Network, a node of the NSF National Nanotechnology Coordinated Infrastructure (NNCI), provides access to researchers across the nation, impacting local universities, not-for-profit institutions and industries. Workshops and training modules will be developed to broaden participation from minority institutions and to educate a new generation of researchers at the intersection of statistics and materials science. The instrument will be integrated into the undergraduate curriculum (MSE 370: Microstructure of Inorganic Materials) and the graduate curriculum being developed under an NSF-funded National Research Traineeship program, which brings together the materials science, statistics and machine learning communities at NC State and NC Central to develop new approaches to materials informatics research. The participation of underrepresented groups at the K-12 levels will be enriched by showcasing the unique and highly-visual 3D microstructural images generated using the PFIB at the NanoDays program (which has an attendance of over 2000 students, parents and teachers). Short courses and full-day advanced workshops will be specifically designed to attract industry and external users. Finally, the diverse range of research topics that will be enabled by the PFIB will have a significant impact on regional industries keenly interested in the three-dimensional multi-modal characterization of microstructures.

The proposed work aims to understand structure-propoerty changes at the insertions.

The need for development and deployment of reliable and efficient energy storage devices, such as lithium-ion rechargeable batteries, is becoming increasingly important due to the scarcity of petroleum. Lithium-ion batteries operate via an electrochemical process in which lithium ions are shuttled between cathode and anode while electrons flowing through an external wire to form an electrical circuit. The study showed that the development of lithium-iron-phosphate (LiFePO4) batteries promises an alternative to conventional lithium-ion batteries, with their potential for high energy capacity and power density, improved safety, and reduced cost. However, current prototype LiFePO4 batteries have been reported to lose capacity over ~3000 charge/discharge cycles or degrade rapidly under high discharging rate. In this proposed work, we hypothesize that the mechanical and structural failures are attributed to dislocations formations. Numerical models and crystal visualizations will provide to further understand the stress development due to lithium movements during charging or discharging. This work will contribute to the fundamental understanding of the mechanisms of capacity loss in lithium-ion battery materials and help the design of better rechargeable batteries, and thus leads to economic and environmental benefits.

The objective of this project is to develop virtual experiments to study extracellular matrix- cell interactions in pulmonary valves. The virtual experiments employ real microstructures of valvular tissues and finite element methods to simulate biaxial loading on tissues and depict changes in collagen fiber orientations and cellular deformations. The interactive content is made possible through the use of a BioTester, photomicrographs and an open source finite element software. Extracellular matrix-cell interactions have been studied in the fields of cell biology and biochemistry, the mechanical interactions have yet to be completely elucidated due to the limitations of physical experimental apparatus. The proposed virtual experiments are designed to aid in understanding mechanical interactions in biological tissues. This information will provide a better understanding of how organ-level biaxial loading translates into altered tissue stress states and cellular deformations.