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4. Materials Fingerprinting Classification

Author

Spannaus, Adam, Law, Kody J. H., Luszczek, Piotr, Nasrin, Farzana, Micucci, Cassie Putman, Liaw, Peter K., Santodonato, Louis J., Keffer, David J., and Maroulas, Vasileios

Subjects
Condensed Matter - Materials Science, Computer Science - Machine Learning, Statistics - Applications
Abstract

Significant progress in many classes of materials could be made with the availability of experimentally-derived large datasets composed of atomic identities and three-dimensional coordinates. Methods for visualizing the local atomic structure, such as atom probe tomography (APT), which routinely generate datasets comprised of millions of atoms, are an important step in realizing this goal. However, state-of-the-art APT instruments generate noisy and sparse datasets that provide information about elemental type, but obscure atomic structures, thus limiting their subsequent value for materials discovery. The application of a materials fingerprinting process, a machine learning algorithm coupled with topological data analysis, provides an avenue by which here-to-fore unprecedented structural information can be extracted from an APT dataset. As a proof of concept, the material fingerprint is applied to high-entropy alloy APT datasets containing body-centered cubic (BCC) and face-centered cubic (FCC) crystal structures. A local atomic configuration centered on an arbitrary atom is assigned a topological descriptor, with which it can be characterized as a BCC or FCC lattice with near perfect accuracy, despite the inherent noise in the dataset. This successful identification of a fingerprint is a crucial first step in the development of algorithms which can extract more nuanced information, such as chemical ordering, from existing datasets of complex materials.

Published
2021
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8. Bayesian Point Set Registration

Author

Spannaus, Adam, Maroulas, Vasileios, Keffer, David J., and Law, Kody J. H.

Subjects
Statistics - Applications
Abstract

Point set registration involves identifying a smooth invertible transformation between corresponding points in two point sets, one of which may be smaller than the other and possibly corrupted by observation noise. This problem is traditionally decomposed into two separate optimization problems: (i) assignment or correspondence, and (ii) identification of the optimal transformation between the ordered point sets. In this work, we propose an approach solving both problems simultaneously. In particular, a coherent Bayesian formulation of the problem results in a marginal posterior distribution on the transformation, which is explored within a Markov chain Monte Carlo scheme. Motivated by Atomic Probe Tomography (APT), in the context of structure inference for high entropy alloys (HEA), we focus on the registration of noisy sparse observations of rigid transformations of a known reference configuration.Lastly, we test our method on synthetic data sets., Comment: 15 pages, 20 figures

Published
2018

12. Novel Kraft Softwood Lignin-Derived Carbon Quantum Dots: Synthesis, Characterization, and In Vitro Cytocompatibility.

Author

Christoph, Eli, Yu, Lu, Newby, Steven D., Rivera Orsini, Michael A., Scroggins, Jakob, Keffer, David J., Harper, David P., and Dhar, Madhu

Subjects
QUANTUM dot synthesis, CYTOCOMPATIBILITY, FOURIER transform infrared spectroscopy, HUMAN stem cells, POISONS, SOFTWOOD
Abstract

Carbon quantum dots (CQDs) have been investigated for biomedical applications in medical imaging due to their fluorescent properties, overall long-term stability, and excellent cytocompatibility and biocompatibility. Lignin is an organic polymer in the tissues of woody plants. It is also considered a byproduct of the wood and pulp industries. Hence, it presents as a renewable source of carbon nanoparticles. In this study, we report the synthesis and material and biological characterization of two colloidal suspensions of CQDs in water derived from lignin-based carbon. One was the native form of CQDs derived from lignin carbon, and the second was doped with nitrogen to evaluate material differences. Material characterization was carried out using various commonly used techniques, including Fourier transform infrared spectroscopy (FTIR), emission and absorbance spectra, zeta potential, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Thin films of CQDs were formed on glass and silicon substrates to assess the in vitro cytocompatibility with human mesenchymal stem cells (hMSCs). Observations suggest that the two forms of CQDs promote cell attachment within 24 h and sustain it for at least 7 days. The overall structure and shape of cells suggest a lack of any adverse or toxic effects of CQDs. The data lay down the novel foundation to support the use of lignin-derived CQDs in tissue engineering applications. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Bayesian Point Set Registration

Author

Spannaus, Adam, Maroulas, Vasileios, Keffer, David J., Law, Kody J. H., Wood, David R., Editor-in-Chief, de Gier, Jan, Series Editor, Praeger, Cheryl E., Series Editor, and Tao, Terence, Series Editor

Published
2019
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22. Outcomes & Observations in the Transfer Success Co-Design in Engineering Disciplines (TranSCEnD) Program at the University of Tennessee, Knoxville.

Author

Ellestad, Rachel McCord, Keffer, David J., Retherford, Jennifer, and kocak, Mary

Abstract

The Transfer Success Co-Design in Engineering Disciplines (TranSCEnD) program was designed to assist in the transition of community college graduates to four-year undergraduate programs in the Tickle College of Engineering at the University of Tennessee Knoxville (UTK). Graduation rates among transfer students are lower than students entering four-year programs in year one, and the TranSCEnD program was deliberately designed to provide these students with academic, social and financial support. Three major components were included to improve cohort-building and thereby impact success. Students admitted to the program (1) engaged in a group summer bridge project, (2) completed a single-term success seminar, and (3) were provided a scholarship for continued informal engagement with the comprehensive TranSCEnD team throughout their years at UTK. The NSF-supported project has entered the fifth and final year of the program and the results of the effort show positive impacts on transfer student success. Students participating in the summer bridge program built lasting relationships with one or more individuals in the same cohort, improving their sense of belonging and community in their initial transition to UTK. The seminar series introduced students to resources on campus and best practices for academic success, and students in the program were well prepared for job fairs. Many engaged in internships and other professional practice activities, and generally engaged with the professional development resources provided on campus. Each year, with the addition of new cohorts, occasional informal meetings with all students in the program were well attended. The financial support provided by the scholarship typically reduced the financial burden in transitioning to a more expensive institution; coupled with introductions to undergraduate research and paid internships, most students were better funded through the program, leading towards improved retention. [ABSTRACT FROM AUTHOR]

Published
2023

32. Performance and Economic Analysis of Organosolv Softwood and Herbaceous Lignins to Activated Carbons as Electrode Materials in Supercapacitors

Author

Yu, Lu, primary, Seabright, Kendhl, additional, Bajaj, Ishan, additional, Keffer, David J., additional, Alonso, David M., additional, Hsieh, Chien-Te, additional, Li, Mi, additional, Chen, Hao, additional, Dai, Sheng, additional, Gandomi, Yasser Ashraf, additional, Maravelias, Christos T., additional, and Harper, David P., additional

Published
2022
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35. In Situ Inelastic Neutron Scattering of Mixed Ch4–Co2 Hydrates

Author

Cladek, Bernadette, primary, Ramirez-Cuesta, A.J., additional, Everett, S. Michelle, additional, McDonnell, Marshall, additional, Daeman, Luke, additional, Cheng, Yongqiang, additional, Carvalho, Paulo H.B. Brant, additional, Tulk, Christopher, additional, Tucker, Matthew G., additional, Keffer, David J., additional, and Rawn, Claudia J., additional

Published
2022
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38. Materials Fingerprinting Classification

Author

Spannaus, Adam, primary, Law, Kody J.H., additional, Luszczek, Piotr, additional, Nasrin, Farzana, additional, Micucci, Cassie Putman, additional, Liaw, Peter K., additional, Santodonato, Louis J., additional, Keffer, David J., additional, and Maroulas, Vasileios, additional

Published
2021
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40. Persistent homology on electron backscatter diffraction data in nano/ultrafine-grained 18Cr–8Ni stainless steel

Author

Gong Na, Wang Yong, Wu Huibin, Maroulas Vasileios, Nasrin Farzana, Rios Orlando, and Keffer David J

Subjects
Austenite, Toughness, Materials science, Annealing (metallurgy), Mechanical Engineering, Condensed Matter Physics, Mechanics of Materials, Nano, General Materials Science, Grain boundary, Deformation (engineering), Composite material, Ductility, Electron backscatter diffraction
Abstract

Nano/ultrafine-grained 18Cr–8Ni stainless steel was produced by severe cold deformation followed by annealing. The effect of annealing temperature on the fraction of high-angle grain boundaries (HAGBs), the kernel average misorientation (KAM), and Schmid factor of steels are revealed through electron backscatter diffraction analysis. The analysis on HAGB, KAM values and Schmid factor frequency provide a mechanistic understanding of the impact of structure on mechanical properties, including hardness, strength, toughness and ductility. In this study, a novel application of persistent homology (PH) was employed to reduce the dimensionality of the information describing the complex processing-structure-property relationship. PH emphasizes the relationship between processing (annealing temperature), structure (distribution of the Schmid factor) and property (strength). Specifically, the PH formalism translates multidimensional data sets into clusters, distinguished by common PH features. In this analysis, two clusters emerge. First, at low annealing temperature, incomplete reversion of austenite in austenitic stainless steels results in materials with a greater fraction of grain boundaries, resulting in high strength and low ductility. Second, at high annealing temperature, fully reversed austenite results in lower, though still acceptable strength and superior ductility. The PH approach is applicable for identifying salient features in complex processing-structure-property relationships and is amenable to analysis of large data sets based on machine learning.

Published
2022

47. A molecular dynamics study of a Nafion polyelectrolyte membrane and the aqueous phase structure for proton transport

Author

Shengting Chu, Junwu Liu, Myvizhi Esai Selvan, Keffer, David J., Edwards, Brain J., and Steele, William V.

Subjects
Molecular dynamics -- Research, Polyelectrolytes -- Chemical properties, Polyelectrolytes -- Structure, Ion-permeable membranes -- Research, Chemicals, plastics and rubber industries
Abstract

A molecular dynamics simulation study of hydrated Nafion at water contents is performed to examine the structure and dynamics of the hydrated polyelectrolyte system. The results have shown that both the local structure of the poorly hydrated hydronium ions and the disconnected nature of the global morphology of the water nanonetwork at low water content have contributed to poor conductivity.

Published
2007

48. Structure and dynamics of a benzenedithiol monolayer on a Au(111) surface

Author

Yongsheng, Leng, Keffer, David J., and Cummings, Peter T.

Subjects
Chemistry, Physical and theoretical -- Research, Monomolecular films -- Research, Gold -- Chemical properties, Molecular dynamics -- Analysis, Chemicals, plastics and rubber industries
Abstract

The universal force filed (UFF) is used to perform molecular dynamics (MD) simulations on an extended Au(III) surface. This technology opens avenues for classical simulations in molecular electronic devices.

Published
2003

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