Engineering Commons^™

Synthesis And Characterization Of Sodium Cathode Materials, He Zhou

McKelvey School of Engineering Theses & Dissertations

As sodium batteries hold great promise as a next-generation energy storage device to replace lithium batteries, the development of sodium battery materials has become increasingly urgent. The current study aims to investigate two potential sodium-ion battery cathode materials, Sodium Vanadium Phosphate, and Sodium Manganese Hexacyanoferrate, optimize the experimental procedures, conduct a systematic analysis of material properties and characterization, and ultimately determine the ideal synthesis conditions for these materials.

In the first part of the study, we focused on optimizing the synthesis of Sodium Vanadium Phosphate. By investigating various synthesis conditions, such as annealing temperature, pressure, ascorbic acid content, and material …

Synthesis, Radiolabeling And Evaluation Of A Suite Of Tracers With 44Sc For Detecting Extracellular Dna, Zhiyao Li

McKelvey School of Engineering Theses & Dissertations

Neutrophil extracellular traps involve the rapid translocation of DNA to the outside of the cell under certain stimuli. This structure forms a fibrous network that is able to limit the spread of pathogens and to kill microorganisms. It has also been shown to be present in various pathological processes such as inflammation, autoimmune diseases, and cancer metastasis. Currently, the formation process of NETs in vivo is being extensively studied. However noninvasive detection and quantitation has yet to be achieved. A class of PET tracers are described here that consists of a DNA dye as the backbone that is labeled with …

Design & Analysis Of Mixed-Mode Integrated Circuit For Pulse-Shape Discrimination, Bryan Orabutt

McKelvey School of Engineering Theses & Dissertations

In nuclear science experiments it is usually necessary to determine the type of radiation, its energy and direction with considerable accuracy. The detection of neutrons and discriminating them from gamma rays is particularly difficult. A popular method of doing so is to measure characteristics intrinsic to the pulse shape of each radiation type in order to perform pulse-shape discrimination (PSD).

Historically, PSD capable systems have been designed with two approaches in mind: specialized analog circuitry, or digital signal processing (DSP). In this work we propose a PSD capable circuit topology using techniques from both the analog and DSP domains. We …

Interfacial Engineering And Photoelectrochemistry Of Patterned Metal/Semiconductor Heterostructures, Che Tan

McKelvey School of Engineering Theses & Dissertations

Photoelectrochemical (PEC) cells enable the conversion of solar energy into storable fuels, which is critical in overcoming the intermittent nature of this largest renewable source. However, the majority of semiconductors used as photoelectrodes in these cells have low conversion efficiencies and/or stabilities. Silicon (Si) is an attractive semiconductor material for photoelectrodes, but the development of efficient Si-based photoanodes is challenging due to their instability in alkaline solutions. Thus, one focus of this dissertation is the design and fabrication of highly stable nickel (Ni)-patterned Si photoanodes through interfacial engineering of the barrier heights. Recently, hot carriers in plasmonic metal nanostructures have …

Aerosol Vapor Synthesis Of Organic Processable Pedot Particles And Measuring Electric Conductivity Using A 3d Printed Probe Station, Yang Lu

McKelvey School of Engineering Theses & Dissertations

Conducting polymers are organic semiconductors characterized by conjugated backbones (alternating single-double bonds) that enable mixed ionic-electronic conductivity. Their polymeric nature, tunable band structure and reversible redox capability have demonstrated fundamental advances in the fields ranging from electrochemical energy storage, sensing, to electro/photo catalysis and neuromorphic engineering. Conjugated backbones, the origin of all the unique physical and chemical properties associated with conducting polymers, prevent their solubility due to high lattice energy which hinders processing. Current solution utilizes a long-chain polymer (PSS) as dopants to render conducting polymer water dispersible (PEDOT:PSS). Nonetheless, PSS is highly acidic and hydrophilic limiting applicability with acid-incompatible …

Structural Organization And Chemical Activity Revealed By New Developments In Single-Molecule Fluorescence And Orientation Imaging, Tianben Ding

McKelvey School of Engineering Theses & Dissertations

Single-molecule (SM) fluorescence and its localization are important and versatile tools for understanding and quantifying dynamical nanoscale behavior of nanoparticles and biological systems. By actively controlling the concentration of fluorescent molecules and precisely localizing individual single molecules, it is possible to overcome the classical diffraction limit and achieve 'super-resolution' with image resolution on the order of 10 nanometers.

Single molecules also can be considered as nanoscale sensors since their fluorescence changes in response to their local nanoenvironment. This dissertation discusses extending this SM approach to resolve heterogeneity and dynamics of nanoscale materials and biophysical structures by using positions and orientations …

Defect Chemistry And Ion Intercalation During The Growth And Solid-State Transformation Of Metal Halide Nanocrystals, Bo Yin

McKelvey School of Engineering Theses & Dissertations

Abstract of the Dissertation

Defect Chemistry and Ion Intercalation During the Growth and Solid-State Transformation of Metal Halide Nanocrystals

Semiconductor metal halides as light-sensitive materials have applications in multiple areas, such as photographic film, antibacterial agents and photocatalysts. One focus of this dissertation is to achieve novel morphologies of ternary silver bromoiodide (AgBr1-xIx, 0

For the silver halide system, we demonstrate that the anion composition of AgBr1-xIx nanocrystals determines their shape through the introduction of twin defects as the nanocrystals are made more iodide-rich. AgBr1-xIx nanocrystals grow as single-phase, solid solutions with the rock salt crystal structure for anions compositions …

Mechanisms Of Calcium Phosphate Mineralization On Biological Interfaces And Their Engineering Applications, Doyoon Kim

McKelvey School of Engineering Theses & Dissertations

All living organisms utilize phosphorus (P) as an essential component of their cell membranes, DNA and RNA, and adenosine triphosphate. Bones, in addition to bearing loads, play an important role in balancing P levels in our bodies. In bones, a network of collagen templates and calcium phosphate (CaP) nanocrystals builds hierarchical levels, from nano- to macroscale. Within this architecture, the thermodynamic properties of CaP minerals are influential. Despite the importance of nucleation, growth, and crystallization in collagen structures for tissue development, little kinetic study of these processes has been conducted due to the limited in situ techniques for monitoring these …

Kcnq1/Kcne1 Interaction In The Cardiac Iks Channel And Its Physiological Consequences, Jiajing Xu

McKelvey School of Engineering Theses & Dissertations

Dynamic conformational changes of ion channel proteins during activation gating determine their function as carriers of current. The relationship between these molecular movements and channel function over the physiological timescale of the action potential (AP) has not been fully established due to limitations of existing techniques. We constructed a library of possible cardiac IKs protein conformations and applied a combination of protein segmentation and energy linearization to study this relationship computationally. Simulations reproduced the effects of the beta-subunit (KCNE1) on the alpha-subunit (KCNQ1) dynamics and function, observed in experiments. Mechanistically, KCNE1 increased the probability of “visiting” conducting pore conformations on …

Two-Component Hydrogel As Biomimetic Vitreous Substitutes, Sruthi Santhanam

McKelvey School of Engineering Theses & Dissertations

The vitreous humor of the eye is a biological hydrogel principally composed of fibrillary collagen interspersed with semi-flexible polyelectrolyte, hyaluronic acid (HA). Certain pathological conditions necessitate its removal and replacement. Current vitreous substitutes, such as silicone oils and perfluorocarbons, are hydrophobic, do not resemble the properties of the vitreous, and have known complications. An ideal vitreous substitute should have properties of the natural vitreous, perform its functions, and be biocompatible in the eye. Inspired by the structure and composition of the natural vitreous, we used bio-mimicry to develop an injectable two-component hydrogel. The hydrogel is composed of a fibrillary gellan, …

The Effect Of Diffusive Transport On Mineral Carbonation In Geologic Carbon Sequestration, Wei Xiong

McKelvey School of Engineering Theses & Dissertations

Geologic carbon sequestration (GCS) is an effective method to mitigate environmental problems due to excessive anthropogenic CO2 emissions. It involves injecting supercritical CO2 into deep geologic formations in which CO2 will ultimately be converted to solid carbonate minerals. Basalt is a promising host rock that is rich in the divalent cations Ca, Mg and Fe that are important for mineral trapping of CO2. Fractures and pores in basalt reservoirs provide substantial surface area for geochemical reactions during carbon sequestration. The transport in fractures and pores is controlled by diffusion. The coupling of diffusive transport and geochemical reactions leads to carbonate …

Cyclotron Production And Biomedical Imaging Applications Of The Pet Isotope Manganese-52, Andrew Lake Wooten

McKelvey School of Engineering Theses & Dissertations

Manganese is an important element for biomedical research because of its roles as an essential micronutrient and as a neurotoxin from chronic elevated exposure, as well as the role of manganese(II) as a paramagnetic core for contrast agents in T1-weighted magnetic resonance imaging (MRI). Using a radiotracer of manganese provides excellent sensitivity for studying these phenomena, but only 52Mn met the criteria for our experiments: (1) a half-life (t1/2=5.6 days) that was long enough to examine timepoints over several days, (2) a half-life that was short enough to emit sufficient counts for a realistic scan time, and (3) emitted radiation …

Environmental Fullerene Chemistry: Elucidating Critical Reaction Pathways And Resulting Products In The Aqueous Phase, Jiewei Wu

McKelvey School of Engineering Theses & Dissertations

As the production of fullerenes and fullerene-based materials approaches industrial scale, there are increasing interests/concerns regarding their (potential) environmental impact(s) upon release. To date, a number of critical, aqueous-based fullerene transformation pathways under environmentally relevant conditions remain poorly understood. Comprehensive, fundamental, and quantitative understanding of the potential (major) reaction pathways and resulting products of fullerene materials, particularly in aquatic systems, is now crucial for their accurate fate, transport, life cycle, risk assessment(s), and thus ultimate material sustainability.

Herein, this dissertation is focused on identifying and elucidating aqueous transformation pathways of fullerene materials, focused on C60 as a model fullerene, under …

Applying Bayesian Machine Learning Methods To Theoretical Surface Science, Shane Carr

McKelvey School of Engineering Theses & Dissertations

Machine learning is a rapidly evolving field in computer science with increasingly many applications to other domains. In this thesis, I present a Bayesian machine learning approach to solving a problem in theoretical surface science: calculating the preferred active site on a catalyst surface for a given adsorbate molecule. I formulate the problem as a low-dimensional objective function. I show how the objective function can be approximated into a certain confidence interval using just one iteration of the self-consistent field (SCF) loop in density functional theory (DFT). I then use Bayesian optimization to perform a global search for the solution. …