Materials Science and Engineering Commons^™

Excited-State Lifetimes Of Dna-Templated Cyanine Dimer, Trimer, And Tetramer Aggregates: The Role Of Exciton Delocalization, Dye Separation, And Dna Heterogeneity, Jonathan S. Huff, Daniel B. Turner, Olga A. Mass, Lance K. Patten, Christopher K. Wilson, Simon K. Roy, Matthew S. Barclay, Bernard Yurke, William B. Knowlton, Paul H. Davis, Ryan D. Pensack

Materials Science and Engineering Faculty Publications and Presentations

DNA-templated molecular (dye) aggregates are a novel class of materials that have garnered attention in a broad range of areas including light harvesting, sensing, and computing. Using DNA to template dye aggregation is attractive due to the relative ease with which DNA nanostructures can be assembled in solution, the diverse array of nanostructures that can be assembled, and the ability to precisely position dyes to within a few Angstroms of one another. These factors, combined with the programmability of DNA, raise the prospect of designer materials custom tailored for specific applications. Although considerable progress has been made in characterizing the …

First-Principles Magnetic Treatment Of The Uranium Nitride (100) Surface And Effect On Corrosion Initiation, Ember L. Sikorski, Brian J. Jaques, Lan Li

Materials Science and Engineering Faculty Publications and Presentations

The magnetic properties of uranium nitride (UN) surfaces are not well understood experimentally or computationally but they have a significant effect on UN performance as a nuclear fuel. We investigated ferromagnetic (FM), antiferromagnetic (AFM), nonmagnetic (NM), and three hybrid magnetic structures of the most stable UN surface (100). To account for electron correlation and metastability, a U-ramp was performed to an effective Hubbard U-term of 2.0 eV. FM was found to be the most energetically favorable magnetic structure. Type 1 AFM slab was optimized to a new magnetic structure consisting of (100) planes with either all spin-up electrons, all spin-down …

Seaweed Polysaccharide In Food Contact Materials (Active Packaging, Intelligent Packaging, Edible Films, And Coatings), Kalpani Y. Perera, Shubham Sharma, Amit K. Jaiswal, Swarna Jaiswal

Articles

Food contact materials (FCMs) are materials that come in contact with food products such as food packaging which play a significant role in the food quality and safety. Plastic, which is a major food packaging material, harms the eco-system, wildlife, and the environment. As a result, numerous researches have been in progress on alternative polymers, which has similar properties as plastic but is also environmentally friendly (biodegradable). In recent years, the utilization of seaweed polysaccharides has piqued interest due to its biodegradability, non-toxicity, antioxidant capabilities, and excellent film formation ability. However, it has a number of drawbacks such as low …

Effect Of Crystal Quality On Twinning Stress In Ni–Mn–Ga Magnetic Shape Memory Alloys, Andrew Armstrong, Peter Müllner

Materials Science and Engineering Faculty Publications and Presentations

Low twinning stress (TS) is a prerequisite for magnetic shape memory functionality in ferromagnetic martensites. We compare Ni₅₀Mn₂₈Ga₂₂ (nominal at.%) single crystals from four different producers to reveal the effect of crystal quality on the TS. Near the reverse martensite transformation, the TS is generally low, about 1 MPa, regardless of mosaicity of up to 1.7° and chemical composition deviations of up to 2 at.% of Mn. Pure type I and type II twin boundaries occur in crystals with smooth chemical composition gradients. The corresponding temperature dependences of TS follow universal linear trends with the …

Improvements To Emissive Plume And Shock Wave Diagnostics And Interpretation During Pulsed Laser Ablation Of Graphite, Timothy I. Calver

Theses and Dissertations

This dissertation covers nanosecond pulsed laser ablation of graphite for 4-5.7 J/cm² fluences with 248 nm and 532 nm lasers in 1-180 Torr helium, argon, nitrogen, air, and mixed gas. Three experiments were performed to improve the interpretation of common diagnostics used to characterize pulsed laser ablation, find simple but universal scaling relationships for comparing dynamics across different materials and ablation conditions, and provide a systematic analysis of graphite emissive plume and shock wave dynamics. A scaling of the Sedov-Taylor energy ratio was developed and validated for a range of studies despite differences in wavelength, pulse duration, fluence, and …

Electrostatic Flocking Of Salt-Treated Microfibers And Nanofiber Yarns For Regenerative Engineering, Alec Mccarthy, Kossi Loic M. Avegnon, Phil A. Holubeck, Demi Brown, Anik Karan, Navatha Shree Sharma, Johnson V. John, Shelbie Weihs, Jazmin Ley, Jingwei Xie

Mechanical Engineering Faculty Publications

Electrostatic flocking is a textile technology that employs a Coulombic driving force to launch short fibers from a charging source towards an adhesive-covered substrate, resulting in a dense array of aligned fibers perpendicular to the substrate. However, electrostatic flocking of insulative polymeric fibers remains a challenge due to their insufficient charge accumulation. We report a facile method to flock electrostatically insulative poly(ε-caprolactone) (PCL) microfibers (MFs) and electrospun PCL nanofiber yarns (NFYs) by incorporating NaCl during pre-flock processing. Both MF and NFY were evaluated for flock functionality, mechanical properties, and biological responses. To demonstrate this platform's diverse applications, standalone flocked NFY …

Laser-Defined Graphene Strain Sensor Directly Fabricated On 3d-Printed Structure, Tyler M. Webb, Twinkle Pandhi, David Estrada

Materials Science and Engineering Faculty Publications and Presentations

A direct-write method to fabricate a strain sensor directly on a structure of interest is reported. In this method, a commercial graphene ink is printed as a square patch (6 mm square) on the structure. The patch is dried at 100 °C for 30 min to remove residual solvents but the printed graphene remains in an insulative state. By scanning a focused laser (830 nm, 100 mW), the graphene becomes electrically conductive and exhibits a piezoresistive effect and a low temperature coefficient of resistance of −0.0006 °C⁻¹. Using this approach, the laser defines a strain sensor pattern on …

Impact Behavior Of Laminated Composites Built With Fique Fibers And Epoxy Resin: A Mechanical Analysis Using Impact And Flexural Behavior, Julian Rua, Mario F. Buchely, Sergio Neves Monteiro, Gloria I. Echeverri, Henry A. Colorado

Materials Science and Engineering Faculty Research & Creative Works

This research analyzes the behavior of natural fiber reinforced laminated polymer composites (NFRPC) under mechanical solicitations. Samples were fabricated with epoxy resin matrix reinforced with a multilayer natural fique fiber in a bi-directional commercial fabric configuration. Different reinforcement contents without additives were prepared taking in the account the simplicity in processing, fabrication cost, and applications in which this material might be used with high performance standards. Charpy notched impact and 3-point bending test were carried out to evaluate the mechanical behavior and the work of fracture, which was improved significatively with the fibers, showing an increase from 5 to 30 …

Tools And Strategies For The Patterning Of Bioactive Molecules And Macromolecules, Daniel J. Valles

Dissertations, Theses, and Capstone Projects

Hypersurface Photolithography (HP) is a printing method for fabricating structures and patterns composed of soft materials bound to solid surfaces and with ~1 micrometer resolution in the x, y, and z dimensions. This platform leverages benign, low intensity light to perform photochemical surface reactions with spatial and temporal control of irradiation, and, as a result, is particularly useful for patterning delicate organic and biological material. In particular, surface- initiated controlled radical polymerizations can be leveraged to create arbitrary polymer and block- copolymer brush patterns. Chapter 1 will review the advances in instrumentation architectures from our group that have made these …

Molecular Dynamics Simulations Of Self-Assemblies In Nature And Nanotechnology, Phu Khanh Tang

Dissertations, Theses, and Capstone Projects

Nature usually divides complex systems into smaller building blocks specializing in a few tasks since one entity cannot achieve everything. Therefore, self-assembly is a robust tool exploited by Nature to build hierarchical systems that accomplish unique functions. The cell membrane distinguishes itself as an example of Nature’s self-assembly, defining and protecting the cell. By mimicking Nature’s designs using synthetically designed self-assemblies, researchers with advanced nanotechnological comprehension can manipulate these synthetic self-assemblies to improve many aspects of modern medicine and materials science. Understanding the competing underlying molecular interactions in self-assembly is always of interest to the academic scientific community and industry. …

Atomistic Simulation Of Desalination, Ian David Durr

Symposium of Student Scholars

Atomistic Simulation of Desalination

Ian Durr, Matheus Prates, and Jungkyu Park

Kennesaw State University

In this research, we investigate the desalination capacity of three-dimensional (3D) carbon nanostructures using molecular dynamics simulations. 3D carbon nanostructures proposed here will filter seawater efficiently because of their multiple layers with holes of tunable sizes. The structure is designed to be flexible, allowing mechanical deformation during daily use. The 3D carbon nanostructure will still possess high thermal conductivity, enabling easy recycle through a simple heating process. Here, we employ LAMMPS, Large-scale Atomic/MolecularMassively Parallel Simulator distributed by Sandia National Laboratories to measure salt ion flux through …

Feedstock Powders For Reactive Structural Materials, Daniel Hastings

Dissertations

Metals as fuels have higher energy density per unit mass or volume compared to any hydrocarbon. At the same time, metals are common structural materials. Exploring metals as reactive structural materials may combine their high energy density with attractive mechanical properties. Preparing such materials, however, is challenging. Requirements that need to be met for applications include density, strength, and stability enabling the component to sustain the structure during its desired operation; added requirements are the amount and rate of the energy release upon impact or shock. Powder technology and additive manufacturing are approaches considered for design of reactive structural materials. …

Towards Quality By Design (Qbd) Of Pharmaceutical Oral Films Loaded With Poorly Watersoluble Drugs, Eylul Cetindag

Dissertations

Oral films are an emerging drug delivery dosage form with numerous advantages such as ease of handling, the possibility to circumvent the first-pass metabolism, better patient compliance, capability for continuous manufacturing, and as a platform for personalized medicine. As films are different from other final dosages by their dimensions and their matrix form, further research is required to better understand the impact of excipient and drug on product performance to assure a consistent and good quality product. Therefore, this dissertation aims to contribute towards the processability and manufacturability of films by examining the impact of the materials and processes. First, …

Development And Characterization Of Composite Membranes For Use In Countercurrent Solvent Extraction, Lydia Neves Rodrigues

Dissertations

Porous membranes having a particular wetting characteristic, hydrophobic or hydrophilic, are used for nondispersive membrane solvent extraction (MSX) where two immiscible phases flow on two sides of the membrane. The aqueous-organic phase interface across which solvent extraction/back extraction occurs remains immobilized on one surface of the membrane. This process requires the pressure of the phase not present in membrane pores to be either equal to or higher than that of the phase present in membrane pores; the excess phase pressure should not exceed a breakthrough pressure. In countercurrent MSX with significant flow pressure drop in each phase, this often poses …

One-Pot Synthesis Of Fe2O3@Fe-N-C Oxygen Reduction Electrocatalyst And Its Performance For Zinc-Air Battery, Hua Lin, Yi-Jin Wu, Jun-Tao Li, Yao Zhou

Journal of Electrochemistry

Oxygen reduction reaction (ORR) plays a profound role in determining cathode performance in metal-air batteries and fuel cells. Owing to its inherently sluggish kinetics, high-performance ORR catalysts which favors the scissoring of O-O bond and formation of O-H bond are a requisite. In this regard, Pt has been explored as the most efficient ORR electrocatalysts. Nevertheless, due to its expensiveness, the usage of Pt catalysts represents one of the major sources of cost in those energy conversion devices. Thus, the development of alternative ORR electrocatalysts with minimized Pt utilization has been widely pursued over the past few decades. Metal-nitrogen-carbon catalysts …

Study On Mxene-Carbon Black/Sulfur Composite In Integrated Electrode Of Lithium-Sulfur Batteries, Ye-Peng Fan, Ye-Qiang Luo, Pei-Kang Shen

Journal of Electrochemistry

Lithium-sulfur (Li-S) batteries are considered as a promising energy storage device due to their ultrahigh theoretical energy density of 2500 Wh·kg^-1 and low cost. However, the practical application of Li-S batteries is seriously limited by their low actual energy density, the shuttle effect of polysulfides (LiPSs), and the insulating nature of sulfur and lithium sulfides. Carbon materials have been developed in the design of sulfur hosts due to their adjustable pore structure and high electrical conductivity, but their non-polar surfaces have weak interactions with LiPSs. Herein, MXene-carbon black/sulfur (Ti₃C₂T_x-CB/S) composites were prepared and …

Preparation Of 3d Semi-Interpenetrated Polymer Networks Polymer Electrolyte For Lithium Metal Battery, Yun-Feng Zhang, Jia-Ying Wang, Xiao-Jie Li, Shi-Yu Zhao, Yang He, Shi-Kang Huo, Ya-Ying Wang, Chang Tan

Journal of Electrochemistry

As the next generation high-energy batteries, lithium metal battery has attracted more and more attention due to its highest specific capacity (3860 mA·h·g^-1) and the lowest anode potential (-3.04 V versus the standard hydrogen electrode, SHE). However, the safety problem caused by lithium dendrite growth is one of the biggest challenges for the commercialization of lithium metal batteries. Single ion conducting polymer electrolytes, which deliver high lithium ion transference number, represent one of the important strategies to inhibit lithium dendrite growth. However, the poor compatibility with electrodes and low ionic conductivity largely limit their practical application. In the …

A Comparison In Structural Transformation Of Li[NiXCoYMnZ]O2 (X = 0.6, 0.85) Cathode Materials In Lithium-Ion Batteries, Li-Juan Li, Zhen-Dong Zhu, Juan Dai, Rong-Rong Wang, Wen Peng

Journal of Electrochemistry

In this paper, the phase transformation voltage ranges of two layered oxide ternary cathode materials, namely, Li(Ni_0.85Co_0.10Mn_0.05)O₂ (referred to Ni85, presenting high Ni content) and Li(Ni_0.6Co_0.2Mn_0.2)O₂ (referred to Ni60, presenting common low Ni content), were classified and determined. The structural differences between high Ni and common low Ni ternary materials were studied in order to understand the structure instability of high nickel material during the charging process. At the same time, the differential capacity (dQ·dV^-1) curves of Ni85 and Ni60 positive …

Storage Performance And Mechanism Of Mose2 Nanospheres In Lithium And Magnesium Ion Batteries, Yi Peng, Wei Zhang, Fang-Zhen Zuo, Hao-Ying Lv, Kai-Jun Hong

Journal of Electrochemistry

Molybdenum diselenide (MoSe₂) is a two-dimensional (2D) transition metal dichalcogenide (TMD) material, attracting wide attention in lithium ion battery (LIB) and exhibiting great potential in next-generation magnesium ion battery (MIB) due to its unique layered structure with fast ion mobility and weak van der Waals interlayer interaction. However, the reported literatures related to MoSe₂ mainly focus on the enhancement of performance in LIB without deep storage mechanisms investigations. Meanwhile,the magnesium storage capacity and mechanisms have not been explored. In this work, MoSe₂ nanospheres were synthesized via wet chemical route and followed by annealing treatment. When used …

Preparation And Characterization Of Thermoplastic Polyurethane-Based Polymer Electrolyte, Li Zhou, Lie Wu, Zhao-Ming Xue

Journal of Electrochemistry

Electrolyte still has to be improved to satisfy the increasingly rigid demands of lithium ion batteries that have higher energy densities. Thermoplastic polyurethane (TPU) has two phase structures of soft segments and hard segments, which can guarantee the electrochemical and physical performances of electrolyte for lithium ion battery. It is now creatively applied to the gel polymer electrolyte matrix of lithium ion batteries. In this paper, a novel polymer membrane based on thermoplastic polyurethane/cellulose acetate (TPU/CA) was prepared by non-solvent induced phase separation (NIPS) method. Further, the TPU/CA blending gel polymer electrolyte (GPE) was prepared by absorbing liquid electrolyte. The …