Physical Sciences and Mathematics Commons^™

Investigation Into The Effectiveness Of G-C3n4 For The Degradation Of Indigo Dye In Aqueous Solution Via Electrocatalysis, Rolando R. Barron Jr

Theses and Dissertations

Indigo dye (IUPAC 2-(3-hydroxy-1H-indol-2-yl)indol-3-one) is one of the most used dyes in the textile industry worldwide with more than 40,000 tons produced each year. It can elicit adverse physiological responses in humans including vomiting, diarrhea, and other gastrointestinal conditions, and it is toxic in large amounts. There is also evidence to suggest that indigo is a teratogen and genotoxic in aquatic life. Environmentally, the enormous amount of indigo used in the textile industry has caused rivers and waterways to run blue as well as severely impacting aquatic and plant ecosystems. The chemicals used in its synthesis are also …

Joint Modelling Of Longitudinal Egfr Trajectory And Time To Acute Kidney Injury In Lung Transplant Patients, Samiha Zakir

Theses and Dissertations

Progressive declines in estimated glomerular filtration rate (eGFR) often precede acute kidney injury (AKI), yet the relationship between eGFR trends and AKI risk remains unclear. This study investigates longitudinal eGFR changes and their association with AKI in 459 lung transplant patients followed for up to 7 years (n = 6419). We applied a piecewise linear mixed-effects model to evaluate eGFR trajectories and a Cox proportional hazards model to assess time to AKI. A joint model was used to explore the interplay between longitudinal and survival processes. Key covariates included gender, age at transplantation, antibody-mediated rejection (AMR), and pre-transplant eGFR. Males …

Photometric Redshifts Of Galaxies In Quasar Fields, Ananthavishnu Santhigiri Unni

Theses and Dissertations

Understanding the gas in and around galaxies is crucial for understanding galaxy evolution. Absorption lines detected in the spectra of background quasars offer a powerful tool to study the gas in and around the intervening galaxies. As a part of an effort to understand how the gas interacts with the stellar component of galaxies, our team previously obtained imaging and spectroscopic observations for a large sample of galaxies using the Hubble Space Telescope (HST), the Very Large Telescope (VLT), and the Atacama Large Millimeter Array (ALMA). This sample includes thousands of galaxies, including many without spectroscopic data. The overall goal …

Understanding The Through-Space Intermolecular Interactions Of Isothiourea Catalysts In Acylation/Silylation Reactions Of Secondary Alcohols, Ziyuan Gong

Theses and Dissertations

Through space interactions, including cation-π interaction, lone pair-πinteraction, steric hinderance etc. play a central role in organocatalytic reaction. They can control the reactivity or the selectivity of an organic reaction. Previous work in our group has already shown that the chiral isothiourea compounds can catalyze the acylation as well as silylation reaction of secondary alcohol with the possible cation-πinteraction between the catalyst and substrate. However, there is lack of study to understand how the delocalization of the positive charge would affect the reaction rate and whether some unexpected inter- or intramolecular interaction could help stabilize …

Dust And Metals In Distant Galaxies, Fatima Elkhatib

Theses and Dissertations

Interstellar dust causes reddening and dimming of light from background objects. To analyze how different the dust in distant galaxies is compared to dust in nearby galaxies, we look at multiple background quasars and try to fit their spectra with various models for known galaxies that have differing dust grain populations combined with a quasar spectrum template. Through fitting these models, we found that dust in most of the foreground galaxies we analyzed is similar to the SMC bar, a relatively thin area selected from the Small Magellanic Cloud (SMC). However, we note that all the objects we studied did …

Analysis And Derivation Of The Compressible Euler System With Nonlinear Velocity Alignment: An Investigation Into Collective Behavior, Mckenzie Meredith Black

Theses and Dissertations

Collective behavior refers to the observable patterns, actions, or movements that emerge within a group of entities, such as individuals, animals, or particles, when they interact with each other. In this study, we concentrate on the pressureless compressible Euler system, expanding it to incorporate a family of nonlinear velocity alignment. This extension represents a nonlinear iteration of the Euler-alignment system within collective dynamics, revealing intriguing asymptotic emergent phenomena such as alignment and flocking. Our investigation explores different types of nonlinearity and nonlocal communication protocols, unveiling a diverse spectrum of asymptotic behaviors within the system.

In focusing on the derivation, we …

Thermodynamic Study Of Ligand Coordination On Lead Halide Perovskite Quantum Dots, Bishal Adhikari

Theses and Dissertations

Inorganic lead halide perovskite (ILHP) has been extensively studied in thin films and bulk crystals as promising materials for their photovoltaic and optoelectronic properties. These are stable enough to be prepared as colloidal quantum dots that can be dispersed, deposited and used to achieve quantum confinement; however, selection of the suitable surface passivating ligand remains challenge for long term stability of the colloidal quantum dots. Several ligand coordination chemistries used to achieve greater stability or specific functions: these can be installed at time of synthesis in some cases they can also be installed to preexisting quantum dots by ligand exchange …

Assessing Relationships Between Water Quality, Precipitation, Land Cover And Stormwater Conveyance Type Across A Range Of Sub-Watersheds In The Southeastern Coastal Zone, Kevencia Sabine Gabriel Faton

Theses and Dissertations

The expansion of urban land use/cover along the coast may degrade water quality by introducing a plethora of pollutants and pathogens that negatively impact human and ecological health. It is hypothesized that anthropogenic contaminants associated with stormwater runoff increase with increasing urban density and vary with the timing and magnitude of rainfall. In this study, we examined land use/cover change and relationships between Escherichia coli (E. coli), turbidity, nutrients, and the timing and magnitude of rainfall in two different types of stormwater conveyances (ditches and ponds) within Murrells Inlet, SC during the summer of 2023. Our results indicate …

Integrated Coastal Science And Dune Management: A South Carolina Perspective, Michelle Harris

Theses and Dissertations

Historically, coastal dunes have been poorly understood from a societal perspective despite their protective role in attenuating incoming waves to reduce onshore flood risk. As developed coastlines promote strategies to design and maintain managed dune systems, it is necessary to ensure these strategies are optimized for dune health and resilience, particularly given the increasing threat of natural and anthropogenic stressors. This dissertation work aims to identify strategies that influence coastal dune management in South Carolina (SC), USA from an integrated approach, including a current use assessment, a mesoscale field-based study on strategy efficacy, and by incorporating a societal assessment and …

Generation And Dimension For Derived Categories, Pat Lank

Theses and Dissertations

This work focuses on problems regarding derived categories arising in algebraic geometry and commutative algebra. There are six chapters regarding generation in the bounded derived category of coherent sheaves over a Noetherian scheme. The targeted topics involve explicitly identifying generators, proving existence results thereof, and producing estimates on Rouquier dimension.

New Deep Learning Approaches To Classical Statistical Problems, Shijie Wang

Theses and Dissertations

The field of deep learning (DL) has received considerable attention in recent years. Thanks to rapid growth in computational power, the ability to collect massive datasets, and improvements in software and algorithms, DL is now routinely applied to areas as diverse as computer vision, natural language processing, and bioinformatics. At the same time, DL is only starting to be explored in the context of classical statistical inference problems such as bootstrapping, quantile regression, and mixture modeling. In this dissertation, we develop new DL methodology for three classical statistical problems: 1) weighted M-estimation, 2) joint quantile regression, and 3) mixing density …

Who Am I As A Learner? The Effects Of A Self-Regulated Learning Intervention On Ninth Graders’ Academic Self-Concepts And Intrinsic Motivation, Kaitlyn Elizabeth Bailey

Theses and Dissertations

The transition from middle school to high school is a notoriously difficult one, and a student’s success in ninth grade is typically a predictor of future success in high school. Unfortunately, many ninth graders struggle to engage in school. Despite their capability to complete the work, these students appear unmotivated and simply disengaged from school. In this action research case study, three students had the opportunity to share their education stories and the experiences that have shaped their academic self-concepts. These students also participated in a self-regulated learning intervention to determine if students’ feelings of autonomy, competence, and relatedness could …

Symmetries Of Del Pezzo Surfaces, Jonathan Smith

Theses and Dissertations

For each del Pezzo surface X of degree d, the action of the automorphism group Aut(X) on the exceptional curves of X induces a map ρ : Aut(X) → W(R_d), where W(R_d) is the Weyl group of a root system R_d dependent on the degree of X. The image of ρ is well defined up to conjugacy in W(R_d), so we say that a group G acts by automorphisms on a del Pezzo surface X of degree d if a representative of the …

Bayesian Joint Modeling Of Longitudinal Data And Interval-Censored Failure Time Data, Yuchen Mao

Theses and Dissertations

Longitudinal data are a collection of repeated observations of the same subjects at different points in time. Interval-censored data arise when the time to the event of interest for each subject is never exactly observed but known to fall between two consecutive points in time. Joint analysis of longitudinal data and interval-censored failure time data can lead to more accurate estimates compared to separate modeling when the correlation among events of interest or intracluster correlation is present. The aim of this dissertation is to develop efficient and reliable joint analyses of longitudinal and interval-censored failure time data using Bayesian methods. …

Building A Framework For Analyzing Non-Linear And Multidimensional Kinetics, Mainak Dhar

Theses and Dissertations

Many materials exhibit multiple rates of molecular relaxation due to structural complexities. Standard linear and one-dimensional kinetic cannot extract all the necessary dynamic information about these systems. This dissertation contributes to an overarching scheme to develop new non-linear and multidimensional kinetic experiments to obtain this information. The studies span computation and experiments, picosecond to second timescales, and both single-molecule and pulsed-laser kinetics

Single-molecule kinetics experiments yield time series that contain information about unique structural and dynamic properties of materials. However, these time series are noisy, and data analysis is challenging. Parametric methods are computationally intensive and require strong, unverifiable assumptions …

On Finite Groups With Essential Dimension 2 Over ℚ, Michael Huggins

Theses and Dissertations

We determine all finite subgroups of Aut(X) which have essential dimension 2 over ℚ, where X is a minimal Del Pezzo surface of degree at least 5. Additionally, finite groups with essential dimension 2 whose order is divisible only by the prime numbers 2 and 3 are classified with the exception of the groups dic ₁₂ , C₁₂, and Dih₂₄, whose essential dimensions remain unknown, but may possibly be equal to 2.

Expanding Tailored Nanomaterials With Precise Spatial And Morphological Control, Mengxue Zhang

Theses and Dissertations

Multicomponent nanocomposites with precise spatial control are important for diverse fields spanning from energy conversion to optoelectronics and catalysis. Traditional methods using hydrophilic interactions alone are limited to random mixtures when multiple nanoparticle (NP) types are combined. To improve capabilities, a new strategy for polymer micelle design combining orthogonal hydrophilic (H) and fluorophobic (F) interactions to independently control two distinct NP populations was developed.

Initial research aimed at understanding F-interaction adjustments, which further enabled the switchability of FNP distribution states (dispersion vs aggregation) within polymer films through immersion annealing. Next, dual-NP assembly was examined using a diblock poly (H-b-F) where …

Generalized Sierpiński Numbers And New Irreducibility Criteria On Legendre Polynomials, Robert Scottfield Groth

Theses and Dissertations

A Sierpiński number is an odd positive integer k such that k·2n +1 is composite for all n ∈ Z+. Similarly, a Riesel number is an odd positive integer k such that k · 2n − 1 is composite for all n ∈ Z+, and a Brier number is a number that is both Sierpiński and Riesel. In this dissertation, we consider a generalization of a Sierpiński number and establish their existence by showing, for every fixed A ≥ 2, there are infinitely many odd positive integers k such that the k · an + 1 is composite for every …

Explorations Of Multi-Carboranyl Thiols And Phosphines, Jared Ross Riffle

Theses and Dissertations

In order to ascribe the impact of substituent groups on the bis-ortho-carborane, closo-{C2B10}-closo-{C2B10} multi-cluster system, the first sulfur-containing biscarborane derivatives were synthesized. Biscarborane dithiol, disulfide, bis(methyl)thioether, as well as multiple dithiolate salts were structurally characterized. The exceedingly long C–C bonds and shortened C–S bonds in biscarborane dithiol and its doubly deprotonated dithiolate salts are indicative of significant delocalization of electron density from the sulfur atoms into the cluster. Additionally, a new concept of ligand ambiphilicity is described where, instead of the involvement of only a single center in a ligand, this amphiphilicity relies on the redox behavior of the indirectly …

Stability Of Space-Time Finite Element Discretizations Of Subdiffusive Time-Fractional Differential Equations, Gabriel Kenneth Staton

Theses and Dissertations

The study of anamolous diffusion, and in particular of subdiffusive time-fractional differential equations, is of great interest for its ability to describe transport of particles through porous media. The time-fractional derivatives in these problems are nonlocal, which notably hinders performance of classical time-stepping methods. As a result, there is significant interest in using simultaneous space-time discretizations for these subdiffusive problems, which have the additional benefit of significantly relaxing the regularity requirements for candidate solutions. These types of Petrov-Galerkin schemes require a careful choice of discretized trial and test spaces in order to guarantee stability; in particular, the usual Galerkin choice …

The Design And Optimization Of Optical Systems For The Detection And Characterization Of Phytoplankton, Caitlyn M. English

Theses and Dissertations

Phytoplankton are among the smallest organisms found in marine and freshwater ecosystems. Despite their small size, phytoplankton play a vital role in sustaining life on Earth as primary producers. Through oxygenic photosynthesis phytoplankton are also responsible for large scale carbon fixation and oxygen production. The distribution of phytoplankton in a given water resource can exhibit a high degree of variability across time and space, and this is in large part due to their varying sensitivities to environmental conditions such as resource availability and grazing by predator organisms. As such, phytoplankton community structure is widely used as an investigative tool for …

Extracting Metamorphic Histories Utilizing U-Pb Laser Ablation Zircon Geochronology From The Southern Appalachians Crystalline Rocks And Detrital Sediment, Meredith Kay Love Gawai

Theses and Dissertations

The southern Appalachian mountain belt is an accretionary orogen that formed in the southeastern United States through several phases of oceanic subduction and continental collision during the Paleozoic Era and culminated in the formation of the supercontinent Pangaea. Although many U-Pb zircon ages have been collected from the igneous, metaigneous and metasedimentary rocks in the crystalline core of the southern Appalachians, there remain opportunities to better reconstruct the metamorphic and magmatic history of the southern Appalachians through the lens of zircon geochronology. Such data are valuable in identifying genetic relationships between candidate terranes of the orogen. Herein, I present laser-ablation …

The Conditioning Of Reservoir Computing And Ng-Rc For Forecasting And The Effects Of Temporal Overparameterization, Daniel Jensen

Theses and Dissertations

Reservoir computing and "Next-generation reservoir computing" built on nonlinear vector autoregression are algorithms for predicting time series given past observations. Both algorithms have been successful in predicting some chaotic dynamical systems, but this success is not theoretically well understood. This paper considers the conditioning of both algorithms and the nature of the solutions found. With either algorithm, the least squares problem which is solved to give parameters as a function of the time series data is ill-conditioned, leading to parameter non-identifiability. Both algorithms fall into the class of "sloppy models." Standard practice to regularize either algorithm includes a bias towards …

Gnn Convergence And Accuracy Analysis On Contextual Stochastic Block Models, Trevor Garrity

Theses and Dissertations

Contextual Stochastic Block Models (cSBMs) are simple generative graph models commonly used to benchmark the performance of Graph Neural Networks (GNNs). In this thesis, I prove how inducing symmetries on general, nonlinear GNNs improves their cross entropy on cSBMs, and I derive the limiting accuracy of linear Graph Convolutional Networks (GCNs) on cSBMs. I use these results to derive the functional form of cross-entropy optimal GCNs on cSBMs and compare them to accuracy optimal GCNs.

Exploring Representations And Inductive Bias For Machine Learning Tasks In Knot Theory, Nathaniel Driggs

Theses and Dissertations

Knot theory is a branch of mathematics that studies embeddings of the circle in $\mathbb{R}^3$ that are equivalent up to ambient isotopy. A link is a knot with one or more component. Knots and links have invariants, or functions from each knot to a set such as the integers or a family of polynomials. Predicting invariants can help us approximate them, understand them better, and find useful ways of representing knots and useful models for other machine learning tasks in knot theory. I perform many supervised learning experiments, predicting signature on a large, wide-ranging dataset using 5 different models and …

Power Series Rings Over Noncommutative Rings: Symmetry, Reversibility, And Semicommutativity, Nolan Ison

Theses and Dissertations

Let R be an associative, unital ring. One topic of interest is to assert R has some property, then determine what properties the polynomial ring R[x] and the power series ring R[[x]] are guaranteed to have. There are many relaxations of commutativity in rings. For example, a ring is said to be symmetric if abc = 0 implies acb = 0 for all a, b, c ∈ R. We discuss a certain construction of symmetric rings that we hope will yield the existence of a symmetric ring R such that the set of nilpotent elements in the power series ring …

Sample Preparation And Acquisition Strategies To Improve Accessibility And Proteome Depth In Single-Cell And Low-Input Proteomics, Sara Madisyn Johnston

Theses and Dissertations

Proteins are responsible for important cellular functions and processes including regulation, structural integrity, signaling, transport, and immune functions. Proteomics directly identifies these proteins and enables deeper characterization of the dynamic cellular environment beyond the capabilities of genomics and transcriptomics. Single-cell proteomics further enhances this approach by capturing cellular heterogeneity, which bulk proteomics obscures due to averaging protein expression across large cell populations. Despite significant advances in single-cell proteomics, continued innovation is necessary to increase workflow accessibility and throughput, minimize peptide losses, and achieve comprehensive coverage of the proteome. This dissertation addresses these challenges by developing improved sample preparation methods, two-dimensional …

Non-Destructive Testing Of Stressed Materials Using X-Ray Diffraction And Second-Harmonic Generation, Melissa Nguyen Lumogdang

Theses and Dissertations

A material in use, anywhere from a plastic bag to common infrastructure, will eventually fail from deformation. When strained, the material chemical structure can change, and that change is dependent on many factors, including the amount of strain and strain rate. Understanding the relationship between physical properties and structural changes due to deformation can allow structural manipulation to achieve the desired physical properties. Additionally, research into non-destructive testing (NDT) methods can be used as supporting evidence for replacing destructive testing methods and possible infield stress monitoring. In this dissertation, X-ray diffraction (XRD) and second-harmonic generation (SHG) are the main NDT …

Homomorphisms Of Peano Continua To Berbered Peano Continua, Logan Kennedy

Theses and Dissertations

The study of wild spaces, Peano continua that contain points that are not semi-locally simply connected, has been of integral importance in the study of low-dimensional wild topology. Mainly investigated from the view point of algebraic topology, the fundamental group has been found to be an indespensible tool in describing these spaces, and their local behavior. In particular, using methods developed by Cannon, Conner, Eda, and Kent demonstrated that all maps from Peano continua to planar or one-dimensional Peano continua are determined uniquely up to homotopy class by their induced homomorphisms on fundamental groups, and that fundamental groups are a …

Innovations In Sample Handling Automation To Increase Accessibility Of Sample-Limited Proteomics, Nathaniel Ben Axtell

Theses and Dissertations

Innovation is the vehicle that drives scientific research forward in virtually every field. Advances in genome sequencing propelled the human genome project to completion in 2003 and set the stage for the era of proteomics. Now decades of innovation in liquid chromatography (LC) and mass spectrometry (MS) have improved sensitivity sufficiently to enable single-cell proteomics and other sample-limited studies. Single-cell proteomics reveal patterns of gene expression that are often obscured by bulk-scale proteomics, leading to the identification of new protein biomarker candidates. Sensitive targeted proteomics is the key to successful translation of low-abundance protein assays into clinical applications. With a …