Physical Sciences and Mathematics Commons^™

Geoelectrical And Hydrochemical Characterization Of Submarine Groundwater Discharge In Florida Bay, Ifeanyi Emmanuel Eze

College of Graduate Studies: Theses & Dissertations

Florida Bay, situated at the southern tip of Everglades National Park and underlain by the Miami Limestone formation, is an ecosystem of global significance. Over the past century, the bay has faced threats such as droughts, seagrass mortality, and hypersalinity. Despite various studies and management efforts, the dynamics of submarine groundwater discharge (SGD) in the region remain underexplored. Given that SGD plays a significant role in the chemical dynamics of coastal ecosystems, it warrants thorough investigation. This study aims to characterize the spatial and temporal patterns of SGD in Florida Bay by surveying three basins – Rankin, Whipray, and Rabbit …

Analyzing The Correlation Between Surface Elevation And Seasonal And Diurnal Surface Temperature Cycles On Mars, Emily A. Dolan

Electronic Theses & Dissertations (2024 - present)

Recent technologies such as the Mars Climate Sounder, the Mars Orbiter Laser Altimeter, and the Curiosity rover have allowed scientists to examine Mars’ surface, climate, and atmospheric dynamics. Surface temperature data from the Mars Climate Sounder (MCS) were collected and seasonal and diurnal cycles were extracted via Fourier regression analysis into a 1° latitude longitude grid. Diurnal cycles were shown to move from west to east across the surface throughout the day, while seasonal cycles moved from north to south. Two key diurnal portions, one in the early morning, and another in the late afternoon, were chosen due to their …

A Comparison Of Arctic And Atlantic Basin Cyclone Predictability From A Climatology And Case Study Perspective, Peyton Capute

Electronic Theses & Dissertations (2024 - present)

Arctic cyclones (ACs) can transport warm, moist air into the Arctic region, which combined with strong winds may lead to rapid declines in sea ice during the summer. As a consequence, accurate sea ice predictions during the summer may rely on being able to predict cyclone-related wind speed and direction, which critically depends on the cyclone track and intensity. Despite this, there are relatively few studies that have documented the predictability of ACs during the summer, beyond a few case studies. In addition, there has been no extensive comparison of whether these cyclones are more or less predictable relative to …

Multi-Activity Student Knowledge And Behavior Modeling Via Transfer Learning, Siqian Zhao

Electronic Theses & Dissertations (2024 - present)

Online education systems have grown in popularity over the past few years, providing abundant opportunities for students to learn. As the number of students using these systems grows, it promotes the development of the Educational Data Mining (EDM) field, which leverages statistical, machine learning, and data mining technologies to explore large-scale educational data and develop methods to better understand student learning.

In this dissertation, we investigate two essential topics in EDM: Student Knowledge Tracing (KT) and Behavior Modeling (BM). KT aims to quantify and model student knowledge gained from learning activities, while BM focuses on tasks such as modeling student …

Understanding Local And Large-Scale Drivers Of Rainfall Variability And Change Over The Hawaiian Islands Region, Katrina Fandrich

Electronic Theses & Dissertations (2024 - present)

Hawaiian rainfall variability is strongly influenced by anthropogenic climate change and natural variability (e.g., Pacific Decadal Oscillation (PDO), Pacific North American (PNA) pattern, El Niño–Southern Oscillation (ENSO)). For local decision-makers and resource managers, understanding the drivers of rainfall variability and change in Hawai‘i is crucial for climate adaptation and mitigation planning. Previous studies have applied statistical and dynamical downscaling to produce high-resolution rainfall projections for the Hawaiian Islands region. However, to date, downscaling has only been used to investigate the influence of anthropogenic forcing on late-century rainfall projections for the Hawaiian Islands. For regions like Hawai’i, that are highly vulnerable …

Chemical Reduction Of Curved Molecular Nanographenes: Metal Intercalation And Core Transformation, Yikun Zhu

Electronic Theses & Dissertations (2024 - present)

The promising lithium storage capacity and fast charge transport rate make graphene a great candidate for energy storage applications. However, the harsh synthetic conditions lead to uneven size distribution and poor solubility, posing limitations on further applications and modifications of graphene and its derivatives. Molecular nanographenes, as graphene cutouts, possess outstanding chemical and physical properties stemming from their parent graphene but also demonstrate such unique features as controllable synthetic conditions, defined molecular structures, uniform size, and relatively good solubility. The improved solubility enables the use of solution chemistry methods for design modifications of molecular nanographenes and for systematical investigation of …

Leveraging Redundancy As A Link Between Spreading Dynamics On And Of Networks, Felipe Xavier Costa

Electronic Theses & Dissertations (2024 - present)

A constant quest in network science has been in the development of methods to identify the most relevant components in a dynamical system solely via the interaction structure amongst its subsystems. This information allows the development of control and intervention strategies in biochemical signaling and epidemic spreading. We highlight the relevant components in heterogeneous dynamical system by their patterns of redundancy, which can connect how dynamics affect network topology and which pathways are necessary to spreading phenomena on networks. In order to measure the redundancies in a large class of empirical systems, we develop the backbone of directed networks methodology, …

Molecular-Level Design Of Heterometallic Precursors For Rechargeable Battery Cathode Materials, Yuxuan Zhang

Electronic Theses & Dissertations (2024 - present)

The synthetic methods for rechargeable battery cathodes are rapidly evolving along with the continuous advancement of the materials themselves. Utilizing precursors for the synthesis of Li- and Na-ion cathode materials are known to ensure a phase-pure product with isotropic element distribution, thereby further enhancing the electrochemical properties of the cathode material. As more cathode materials with complex compositions continue to emerge, the strategies for designing the corresponding precursors are also getting diversified. One of the most promising directions is the employment of single-source precursors (SSPs), defined as molecules that contain all necessary elements in the proper ratio and decomposable under …

Sources And Significance Of Symmetric Instability In The Outflow Layer Of Tropical Cyclones, Minghao Zhou

Electronic Theses & Dissertations (2024 - present)

The tropical cyclone (TC) outflow layer is an integral part of the TC transverse circulation: warm and moist air converges in the boundary layer of the TC; rising motion and condensational heating occur in the TC eyewall and rainbands; the TC warm core and divergent anticyclone establish in the mid-upper troposphere, with the mass imported into the TC center exported away through outflow near the tropopause.

A series of state-of-the-art numerical simulations were utilized to investigate different scenarios of TC outflow evolution, from an idealized axisymmetric setup to a semi-idealized asymmetric setup, to a real-case setup of TC–trough interaction. Large …

The Effectiveness Of Cybersecurity Training, Courtney Knight

Electronic Theses & Dissertations (2024 - present)

This study seeks to answer the question of what kinds of cybersecurity training are effective by reviewing the existing literature, analyzing for gaps, and bridging the connection with known learning techniques. The research is exploratory in nature, and is inductive – intending to develop a theory. Additionally, this study seeks to offer a taxonomy of cybersecurity training methods to be evaluated.

This study did not include security operation center (SOC), cyber incident response teams (CIRTs), or other types of advanced cybersecurity professional training. This research specifically focuses on training to improve the average employee and population’s tactical cybersecurity skills.

Several …

Diatom Productivity And Nutrient Dynamics In The Ross Sea, Antarctica During Warm Events In The Neogene, Marialena Christopoulou

Graduate Research Theses & Dissertations

Increased melting of the Antarctic Ice Sheet (AIS) in recent decades, has had a significant impact on many aspects of the global ocean. Models indicate that by the end of the 21st century atmospheric carbon dioxide (CO2) concentrations may exceed 500 ppm, and the average global temperature will likely warm by more than 2°C. However, data that provide model constraints on potential feedbacks in ice-ocean-atmosphere system are limited by short-timescales (e.g., decadal- to centennial-scale) and incomplete spatial coverage. In particular, little is known about the impacts of future warming and widespread melting of AIS on marine biological productivity, silicate weathering …

Inhaling The Unseen: Exploring The Presence Of Microplastics In The Human Respiratory Tract, Kara Coffman-Rea

Graduate Research Theses & Dissertations

Microplastics (plastic pieces less than 5 mm) have emerged as a pervasive form of pollution acknowledged as a universal threat to both environmental and human health. Their small size and widespread distribution pose significant risks to marine life, terrestrial ecosystems, and ultimately human health. Microplastics have been reported in food and drink items designated for human consumption, in cosmetics and consumer goods designed for human use, and within the air we breathe, each providing an entry route for microplastics to enter the human body. Recently, microplastic particles have been detected in a variety of human tissue samples (e.g., lung tissue). …

Applications Of Shape Analysis, Yang Zhang

Graduate Research Theses & Dissertations

Shape analysis is a field of Statistics focused on analyzing and understanding the shape or the geometric properties of objects. We utilize the Bayesian circular cubic smoothing splines to estimate the shapes and introduce a rotation-based alignment method. A simulation study investigates the effect of shape alignment. As an application, we estimate the shapes of hourly crime rates in urban centers across the United States and compare the aligned shapes for different types and locations of crimes. In addition, we apply the proposed shape estimation with alignment to the survival analysis for the length of hospitalization of COVID-19 patients in …

Addressing The Effects Of Counterion Size On The Properties Of Electrochemically Doped Conjugated Polymers, Kyle Baustert

Theses and Dissertations--Chemistry

Conjugated polymers (CPs) are an emerging class of materials that are attractive for many applications due to their low cost, flexibility, and ease of processing. Both chemical and electrochemical doping of CPs is done to alter important properties such as their electrical conductivities and optical absorbances. This ability to tune their properties allows for their use in devices such as organic electrochemical transistors (OECTs) for biosensing and bioelectronics, electrochromic devices for color changing windows, as well as wearable thermoelectrics to use body heat to power wearable electronics. There are several factors that can influence the properties of doped CPs including …

Single-Atom Catalysts For Electrochemical Energy Conversion: Copper Single-Atom Catalyst For Oxygen Reduction Reaction And Quantification Of Site Density By Co Stripping Voltammetry, Dawatage Perera

Theses and Dissertations--Chemistry

Fuel cells are considered a promising technology for achieving cleaner and more sustainable energy production and utilization. However, one of the current major challenges is the economic viability associated with the extensive use of Pt group metal (PGM) catalysts, particularly on the cathode side. Therefore, non-PGM single-atom catalysts (SACs) have received considerable attention as alternatives for PGM catalysts in the oxygen reduction reaction (ORR), which occurs at the cathode of the fuel cell. Among various SAC structures, the non-PGM/nitrogen-doped carbon-based structure (M-N-C) stands out for its excellent ORR performance.

Chapter 2 illustrates the use of copper metal in place of …

Effect Of Π-Conjugated Ligands And A* Site Organic Cations On The Energetic Properties And Photovoltaic Performance Of Metal Halide Perovskites, Harindi R. Atapattu

Theses and Dissertations--Chemistry

Metal halide perovskites have gained interest in optoelectronic applications such as photovoltaics, lasers, LEDs, transistors, and photodetectors due to their excellent semiconducting properties considering their low cost. Metal halide perovskite (HP) photovoltaics have rapidly increased in power conversion efficiency (PCE), which now exceeds 25%. HPs have gained attention in these applications due to their high tolerance towards defects, long charge carrier diffusion lengths, high charge carrier mobility, high optical absorption, and bandgaps that are tunable over a large range. Even though HP photovoltaic PCEs are improved these are still not commercially available due to them showing lower stability and energy …

Understanding Of Processing Additives Influence In Tin Halide Perovskites: Chemistry, Defect, And Photovoltaic Performance, Syed Rahmath Ullah Joy

Theses and Dissertations--Chemistry

Metal halide perovskite semiconductors have attracted much interest for various applications, such as solar cells, light emitting diodes, photodetectors, and lasers, due to their excellent optoelectronic properties. Photovoltaic cell development is centered on Pb-based perovskites, which have equal photovoltaic performance compared to the traditional silicon photovoltaic. But concerns arising from the usage of toxic lead metal have motivated the research community to seek an alternative derivative. Among those, tin halide perovskites show much promise as an alternative to Pb-counterparts due to their ideal bandgap for single junction photovoltaics and similar optoelectronic properties to Pb perovskites. Nevertheless, tin perovskites suffer from …

Synthetic Strategies Toward The Development Of Stable Gold-Based Anticancer Agents And Their Mechanistic Insight, Adedamola Arojojoye

Theses and Dissertations--Chemistry

Despite notable advancements in the design and synthesis of novel chemotherapeutic drugs, cancer continues to be a leading cause of death in the United States. Metallodrugs, especially Au complexes, have played a prominent role in the search for the next generation of chemotherapeutic agents. Herein, I report on the synthetic strategies towards the rational design of stable Au (Au)-based agents, study their reactivity in biological environment, and offer insights into the cytotoxic mechanism of action in cancer. Chemotherapeutic Au compounds exist mainly in +I or +III oxidation states. Repurposing of the Au(I) FDA approved auranofin for the treatment of diseases …

Synthesis, Functionalization, And Application Of Polymeric Membrane Blends Of Polysulfone, Poly-Ether Ether-Ketone, And Natural Fiber Additive Biochar For Optimal Water Treatment., Abelline Katusiime Fionah

Theses and Dissertations--Chemistry

According to the Center for disease control (CDC), an estimated 1.7 to 2.2 million persons die from waterborne diseases annually. The majority of individuals dying from diseases resulting from unsafe drinking water, such as diarrhea and gastroenteritis, are children. This has in turn created a global water crisis. Different methods have been developed to treat contaminated water in response to the global water crisis such as adsorption, filtration, ozonolysis, catalysis, etc. Of the methods available, filtration via polymeric membranes has been one of the most successfully applied. A membrane is a thin semi-permeable barrier (often made of a polymer) used …

Hunting Types In North American Eocene And Oligocene Carnivores And Implications For Nimravid Extinction, Miguel Andres Castellanos

Graduate Research Theses & Dissertations

The late Eocene and Oligocene is traditionally seen as a time of great climactic shift, with open habitats beginning to appear and forests receding. This time period saw both the diversification and subsequent extinction of North American nimravids. The causes of the extinction of this early sabertooth group in the Arikareean remain unclear. One possibility for their decline is that nimravids were competitively disadvantaged in open habitats relative to contemporary, possibly more cursorial caniform predators. Here I analyze and compare the hunting styles of Eocene and Oligocene predators in correlation with their ecological implications via discriminant function analysis of the …

Microwave Simulations Of A Beam Position Monitor And Circuit Designs Assisting Its Beam Testing, Marc Jacob Crowell

Graduate Research Theses & Dissertations

Beam position monitors (BPMs) are non-destructive diagnostic devices widely used in particle accelerators. I will first introduce the need for precision beam position measurement in particle accelerators, and then provide an overview of various types of BPMs. For the first part of my work, I focus on the design and simulation of a button-BPM. Microwave and wakefield simulations were performed to characterize the output signals. Such a design could find a potential application at the Argonne Wakefield Accelerator (AWA) at the Argonne National Laboratory. Although no BPMs have been fabricated to this date, a future beam experiment will be needed …

Theory Of Ultrafast Spin Crossover In Divalent Iron Systems, William Baker

Graduate Research Theses & Dissertations

A theory to account for the ultrafast, i.e. femtosecond timescale, singlet to quintet spin crossover in divalent iron molecules is developed. The model considers an iron cluster with ligands extending in all 6 cardinal directions initially at rest in a low spin singlet ground state. An optical excitation excites an electron from the d orbitals to the ligands, changing the system from the metal centered (MC) singlet state to the metal to ligand charge transfer (MLCT) singlet state. Experimentally, it is known that the system eventually relaxes into the quintet MC state, but there are no satisfactory explanations that model …

Applying Synchrotron Saxs And Xas To Study The Microstructure Of Energy Conversion And Storage Materials, Lingzhe Fang

Graduate Research Theses & Dissertations

The microstructure of energy conversion and storage materials is a key determinant of physical properties and electrochemical performance. Synchrotron X-ray techniques, with their strengths of high flux and exceptional brightness, play an irreplaceable role in understanding nano and sub-nano structures. This helps the study of reaction mechanisms and benefits material design in energy conversion and storage area. Electrifying CO2 transformation using renewable energy offers a carbon-neutral solution to CO2 recycling and fuel generation. Among various feedstocks from the CO2 reduction reaction, CO, HCOOH, and CH4 have approached the performance thresholds for industry implementation. The application of single atom catalysts (SACs) …

Gas-Phase Mass Spectrometry Studies Of Ternary Metal Carboxylate Complexes, Anthony James Fanizza

Graduate Research Theses & Dissertations

In the wake of climate change from rising CO2 emissions and with peak oil looming, the dive into sustainable fuels and energy is becoming increasingly essential. This dissertation investigates ternary ligand-metal cationic complexes for potential catalytic applications in the decarboxylation of carboxylic acids to produce bioavailable and carbon-neutral fuel sources. By utilizing gas-phase reactivity studies via mass spectrometry, namely, collision-induced dissociation and ion-molecule reactions, mechanisms can be elucidated in a regulated chemical environment. When paired with density functional theory calculations for molecular geometries, chemical interactions, charge densities, and energetics, system efficiencies can be further clarified presenting a more complete mechanistic …

Pathology And Diagnosis In Inflammatory-Related Diseases: Covid-19 And Age-Related Macular Degeneration, Zane Russell Lacasse

Graduate Research Theses & Dissertations

Chronic inflammation and dysfunctional inflammatory responses are believed to be contributing factors to the severity of many diseases. Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it has been recognized that levels of inflammatory markers and the severity of coronavirus disease-2019 (COVID-19) cases are closely related. The work within this dissertation begins with establishing an alternative platform for the diagnosis of COVID-19 and explores ways to enhance the diagnostic utility of this platform. An alternative route for COVID-19 diagnosis was explored using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS). The platform utilizes a non-invasive sampling technique …

Forecasting The One Month Ahead Joint Distribution Of The Carhart Four Factor Model Using A Copula Method, Michael Nebor

Graduate Research Theses & Dissertations

The Fama and French created factors of Market minus Risk Free (Mkt-RF), Small minusBig (SMB), High minus Low (HML), and the Carhart developed factor of Momentum (MOM) are frequently used together as a four factor model to explain the variation in returns of financial equities. This paper analyzes the joint distribution of these factors by forecasting the one month ahead joint distribution using various copula based methods. The VaR quantiles are calculated throughout the forecasted distribution at the .01, .05, .25, .50, .75, .95, and .99 quantiles. The forecasted distributions are compared against each other by analyzing the exceedances of …

Mixed Mechanisms Of Multi-Site Phosphorylation, Suha Jayyousi Dajani

Graduate Research Theses & Dissertations

Multi-site phosphorylation is an important mechanism in cell biology that regulates protein function and activity. It also plays a critical role in a wide variety of cellular processes that control intra-cellular signaling. Studies on mono- and dual-site phosphorylation have been conducted theoretically and experimentally by researchers. However, there is little research on triple-site and multi-site mixed mechanism phosphorylation.

The aim of this research is to study and identify the number of positive steady states (multistationarity) in a mathematical model of a triple-site mixed mechanism, processive and distributive, phosphorylation network. This research is accomplished by means of ordinary differential equations, Jacobian …

On The Ground And From Above: A Multi-Factor Analysis Of The Direct And Indirect Drivers Of Tallgrass Prairie Small Mammal Communities, Erin Rowland-Schaefer

Graduate Research Theses & Dissertations

Tallgrass prairies are among the most globally threatened ecosystems, with only one percent of the historical extent remaining in Illinois. Prairie restoration is an essential strategy to preserve biodiversity and reestablish threatened species. Practitioners use management tools to shift the landscape context of prairie restoration sites, such as prescribed fire and land cover change. Managers can also impact the landscape connectivity and edge proximity of certain areas through the use of mowed driving lanes. The effects of these factors on small mammals, which are central in tallgrass prairie food webs and relevant to human health and restoration success, are not …

Effort Of Reproducibility: Metrics, Methods, And Models To Navigate The Landscape Of Reproducible Research, Akhil Pandey Akella

Graduate Research Theses & Dissertations

Validating scientific claims is an elaborate process that involves researchers investing considerable time and effort to discover the validity of claims. It involves repeatability, reproducibility, and replicability, where each subsequent step requires increased effort and time. With the evolving nature of computational experiments and the exponential pace at which scientific publications are disseminated, researchers find it challenging to devote time, energy, and resources to assess claims made in papers of interest. Preemptive signals for reproducible effort can be helpful to researchers in filtering academic works of interest, thereby allowing them to adjust efforts based on need. Through this research, I …

Using Ex-Situ And In-Situ Mössbauer Spectroscopy To Study The Degradation Of Nafe(1−X)(Ni0.5mn0.5)X O2 Batteries, Iddrisu Bachokun Abdul Razak

Graduate Research Theses & Dissertations

Sodium-ion batteries are an attractive alternative to traditional lithium-ion batteries due to their low cost and eco-friendly components. The Fe3+/Fe4+ redox reaction provides similar operating voltages and specific energy densities to that of lithium-ion batteries. Mössbauer spectroscopy is a useful x-ray technique for measuring the chemical environment inside of the metal enclosure of batteries. In particular, it can measure the relative concentration of Fe3+/Fe4+ ions as a function of the battery’s voltage. In this dissertation ex-situ and in-situ Mössbauer spectroscopy were used to map out the effect of various electrolytes on the performance of NaFe(1−x)(Ni0.5Mn0.5)xO2 batteries. This was done by …