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Investigation Of Optically Pumped Gesn Quantum Well Lasers, Grey Steven Abernathy

Graduate Theses and Dissertations

Silicon photonic integrated circuits enable the capability of producing on-chip processing of photonic signals, including both emission and detection. Emission materials, however, have been limited for monolithic integration due to high processing temperatures, indirect bandgap materials, and material integration complications. The (Si)GeSn material system has recently attracted attention due to the bandgap transition from the Si and Ge, naturally indirect bandgap, to direct bandgap with sufficient Sn incorporation. Additionally, the low growth temperature (CMOS compatible; <400 >°C) of (Si)GeSn materials can enable the monolithic integration of the highly desired mid-infrared light emission on the Si Photonic platform. This dissertation first discusses …

Smartphone Gaming And International Students: Exploring The Experiences Of Hypercasual Gameplay For Practicing English Vocabulary And Learning About The United States Culture In Mediated Action, Se He Hwang

Graduate Theses and Dissertations

The use of smartphones in everyday settings is widespread, and people around the world use smartphones not only for making phone calls and sending text messages but also as a tool for searching for information and playing smartphone games during their free time. Since people around the world have easy access to smartphones regardless of their physical locations, smartphones can function as a tool for learning purposes, and playing games for learning purposes also supports the students to learn information in less stressful settings since playing games is predominantly for entertainment. The purpose of this qualitative phenomenological study in mediated …

Computational Alchemy: Pioneering Spintronic, Thermoelectric, And Optoelectronic Materials Design Through First-Principles Calculations And Machine Learning, Eesha Sanjay Andharia

Graduate Theses and Dissertations

Intelligent materials discovery and design plays a pivotal role in advancement of spintronics, optoelectronics and thermoelectric devices and technology. In this study, we investigate three types of materials using first principles calculations. First, the structural, electronic, and magnetic properties of CrTiCoZ (Z = Al, Si) equiatomic quaternary Heusler alloys were investigated. CrTiCoAl compound was found to exhibit a half metallic ferromagnetic structure and Curie temperature above room temperature, which makes it an ideal candidate for magnetic tunnel junction, the basic building block of Spintronic devices. Second, we use Green’s function to obtain the finite temperature phonons by including quartic anharmonicity …

Quantifying Physical Function: Moving Towards A New Definition And Better Assessment, Anthony Campitelli

Graduate Theses and Dissertations

Though poor physical function (PF) and disability are two of the most impactful problems facing older adults today, the field of kinesiology has not yet devised a method of measuring PF, thus limiting investigations with the potential to lead to improved PF interventions and assessments. This dissertation aimed to develop a single, continuous measure of PF using a latent variable modeling approach, and then use the generated scores to evaluate the role of lower body muscular power in PF assessment and to construct an improved PF assessment battery for predicting overall PF. Each aim of this dissertation was addressed through …

Understanding And Control Of Frustration And Topological Defects In Ferroic Matter, Suyash Rijal

Graduate Theses and Dissertations

Ferroic matter are of great importance as they provide a platform to extend the understanding of many-body physics and also for their amazing functional properties relevant for technological advancements. The work in this dissertation is dedicated to two of such ferroic materials.

First is CrGeTe₃ (CGT), a two dimensional (2D) magnet discovered in 2017. The discovery of two-dimensional magnetism has invigorated the research community as their low dimensionality offers a unique avenue to understand and investigate the origin of magnetism in these atomically thin systems and harvest diverse application such as information processing, storage and transfer using their magnetic …

Contributors To Faculty Wellness In An Academic Emergency Department Before And During The Pandemic: A Qualitative Study, Nicholas D. Hartman, Casey Glass, Manoj Pariyadath, Kathleen Hosmer, Meagan Hunt, Nicklaus Ashburn, Cedric Lefebvre

Journal of Wellness

Introduction: Burnout is well known as a prevalent hazard in emergency medicine (EM) careers, but the literature is less clear about what specific work-related factors actually contribute to wellness and burnout among academic EM faculty.

Objectives: 1) To explore themes and specific concerns that contribute to faculty wellness in an academic emergency department, in a qualitative fashion. 2) To determine whether these themes and concerns changed appreciably in the time of the COVID-19 pandemic.

Methods: EM faculty members at an academic institution were invited to participate in the study, including an on-line survey and a structured interview. Survey results were …

Nano Curcumin As A Photosensitizer For Photodynamic Therapy Treatment Of Oral Lesions, Sudip Pokhrel

Graduate Masters Theses

The capability of curcumin and its analogs to inhibit various processes involved in cancer development and progression has been extensively studied. Curcumin is also a photoactive compound, which can be activated with blue light to initiate photochemistry. Motivated by this and its inherent anti-cancer properties, we examined the practicality of using a commercially available nano-cumin formulation as a photosensitizer for the photodynamic therapy (PDT) treatment of oral cancers. Despite the significant limitation of curcumin in only absorbing blue light, which lies outside the optical window and suffers from poor penetration depths, we meticulously investigated its potential. Our systematic examination using …

Gray Seal (Halichoerus Grypus) Diet And Microplastic Ingestion On Great Point, Nantucket, Shannon R. Brown

Graduate Masters Theses

Due to their semi-aquatic lifestyle, pinnipeds are an ideal sentinel group used to study anthropogenic threats to the marine environment. Microplastics, primarily transported to the ocean through river discharge or weathering of larger plastics, are a threat to both pinnipeds and humans. Bioaccumulation of microplastics within the marine food web has been observed, with pinnipeds indirectly ingesting microplastics through their prey. As generalists, gray seals (Halichoerus grypus) are a pinniped species that can provide information on microplastic exposure to many lower trophic level organisms. This thesis explores the relationship between the diet and microplastic ingestion of gray seals on Great …

Energetics And Passivation Of Surface Defects In Hgte Colloidal Quantum Dots, Jacob D. Eisensmith

Theses

Colloidal quantum dots (CQDs), and especially HgTe CQDs, have the potential to disrupt traditional solid-state manufacturing of sensitive infrared photodetectors. Here we produce a surface model for (111) HgTe surfaces present in tetrahedral CQDs and attempt to use density functional theory (DFT) to explore various issues in the fabrication and performance of HgTe CQD photodetectors. One such concern is the presence of mid-gap trap states that can hurt device performance. In this work, we demonstrate that an abundant source of these trap states is unpassivated mercury at the surface of the nanocrystal, which can be corrected with passivation procedures. Furthermore, …

Enhancing Thermal Stability Of Perovskite Solar Cells Through Thermal Transition And Thin Film Crystallization Engineering Of Polymeric Hole Transport Layers, Sanggyun Kim, Sina Sabury, Carlo A. R. Perini, Tareq Hossain, Augustine O. Yusuf, Xiangyu Xiao, Ruipeng Li, Kenneth R. Graham, John R. Reynolds, Juan-Pablo Correa-Baena

Chemical and Materials Engineering Faculty Publications

Organic hole transport layers (HTLs) have been known to be susceptible to thermal stress, leading to poor long- term stability in perovskite solar cells (PSCs). We synthesized three 2,5-dialkoxy-substituted, 1,4-bis(2-thienyl)phenylene (TPT)-based conjugated polymers (CPs) linked with thiophene-based (thiophene (T) and thienothiophene (TT)) comonomers and evaluated them as HTLs in n-i-p PSCs. TPT-T (MB/C6), which has branched 2- methylbutyl and linear hexyl (MB/C6) side chains, emerged as a promising HTL candidate, enabling power conversion efficiencies (PCEs) greater than 15%. In addition, PSCs with this HTL showed an improvement in long-term stability at elevated temperatures of 65 °C when compared to those …

Unveiling The Intercompartmental Signaling Axis: Mitochondrial To Er Stress Response (Mersr) And Its Impact On Proteostasis, Jeson Li

Dissertations and Theses (Open Access)

Maintaining protein homeostasis is essential for cellular health. During times of protein stress, cells deploy unique defense mechanisms to achieve resolution. Our previous research uncovered a cross-compartmental Mitochondrial to Cytosolic Stress Response (MCSR), a unique stress response activated by the perturbation of mitochondrial proteostasis, which ultimately results in the improvement of proteostasis in the cytosol. Here, we found that this signaling axis also influences the unfolded protein response of the endoplasmic reticulum (UPRER), suggesting the presence of a Mitochondria to ER Stress Response (MERSR). During MERSR, the IRE1 branch of UPRER is inhibited, introducing a previously unknown regulatory component of …

South Carolina Instructional Leaders’ Conceptualization And Perception Of Learning Thrill: An Exploratory Interview Study, David Paul Cupolo

Electronic Theses and Dissertations

Numerous students across the United States are observed as being disengaged and bored in several of their learning experiences. Similarly, innumerable students also self-report being bored and disengaged. Over 40% of South Carolina (SC) students in Grades 3–8 report being compliant, disengaged, or mixed in all three domains (behaviorally, cognitively, and emotionally). Hattie and Donoghue propose a new conceptual learning model—skill, will, and thrill. They suggest that this model will improve student learning experiences to the transfer level, which is thrill. At the thrill level, students can then apply their learning to similar or different contexts. As the concept of …

Characterizing Groundwater Flow Across The Barrier Island-High Marsh Interface, Dean Michael Wrobel

Electronic Theses and Dissertations

The freshwater resources of barrier islands are influenced by a variety of hydrogeologic factors, which create unique regions of groundwater composition. Factors including evapotranspiration, geologic constraints, tidal forcing, and meteoric inputs influence subterranean flow creating a groundwater salinity gradient throughout the island-marsh setting which directly influences the spatial distribution of dominant vegetation on the island. Rising sea levels and variation in local climate may alter the hydrologic balance on barrier islands, potentially shifting salinity gradients and ecological baselines on short timescales. The intrusion of saltwater into the barrier island freshwater system could result in the shifting of ecotones and potential …

Navigating The Black Student First-Year Experience: Exploring Ways Peer Mentoring Can Enhance Engagement And Belonging At A Pwi, Richard V. Frazier Iii

Electronic Theses and Dissertations

Studies indicate that minoritized students attending Predominantly White Institutions (PWI) may struggle with engagement and establishing a sense of belonging. Peer mentoring may play a role in enhancing these opportunities to foster academic performance and retention. The sense of belonging and engagement for minoritized students at a PWI is essential to their academic sustainability. This qualitative narrative analysis study uses Strayhorn’s (2012) theory of college students’ sense of belonging as the theoretical framework to explore the peer mentoring experiences of 10 Black first-year students participating in a stand-alone model. Interviews were used to acquire insight into peer mentoring’s influence on …

Tidal Creeks As Conduits Of Land-Derived Nutrients To The Coastal Ocean, Christianna R. Morton

Electronic Theses and Dissertations

A common feature of the coastline of South Carolina are small, low relief, tidal creek systems. Due to their tidally dominated nature, these systems can act as conduits of land-based nutrients to the coastal ocean. As development along the coastline increases, the volume of nutrients entering tidal creeks will likely exhibit an associated increase. The focus of this research is an investigation of the input of nutrients into White Point Swash, a tidal creek located in northern South Carolina, via point and nonpoint sources, the behavior of nutrients once they enter this system, and the potential removal of nutrients by …

Exploring The Community Standards Review For College Admission: A Comparative Case Study, Kayla E. Johnson

Electronic Theses and Dissertations

Many higher education institutions review the disciplinary and criminal history of applicants to assess potential threats and ensure a safe learning community in the college admissions process. This review is often criticized for exacerbating the opportunity gap and racial disparities for marginalized populations and creating barriers to college admission. This study explores the institutional processes for community standards review at four public regionally accredited 4-year institutions and how diversity, equity, and inclusion (DEI) influence the community standards review process. Three research questions guided the study: How do college administrators at 4-year public universities describe their perceptions of the community standards …

Synthesis Of Selenium Nanostructures: Rods, Wires, And Fibers By Pulsed Laser Ablation In Liquids, Atikur Rahman

Theses and Dissertations

Selenium is a semiconductor that has a bulk energy bandgap of 1.74 eV, is mainly used in sensors, rectifiers, and advanced photovoltaic solar cells. Selenium is very important for the energy applications and was declared as Energy Critical Element (ECE) by the American Physical Society (APS) and the Materials Research Society (MRS). The goal of this dissertation was to control the growth of selenium when being irradiated by a pulsed laser within a liquid environment. The method called “Pulsed Laser Ablation in Liquids” is a green synthesis technique that allows for ligand-free nanoparticles to be created. Laser repetition rates were …

Exploring Intraplate Seismicity In The Midwest, Alexa Fernández

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Intraplate seismicity represents a notable occurrence within the stable North American Craton. This research explores the potential sources of stresses that could reactivate older faults and influence seismic activity within this region. Among these sources, the enduring impact of the last glacial period is considered, which includes continued glacial isostatic adjustments (GIA). During GIA the lithosphere rebounds due to the retreating ice, and the forebulge caused by far-field flexure in response to the glacial load, collapses. This results in significant faulting, fracturing, and seismic activity associated with the deglaciation phase. The adjustment of the lithosphere manifests as both near surface …

My Last Concussion, Shannon Valkr

Department of English: Dissertations, Theses, and Student Research

MY LAST CONCUSSION is a thesis consisting of a critical introduction, a number of poetic influences, and a collection of poems. The introduction touches on the themes of the collection, my personal history with my subject, my changing approach to poetry, and a brief evaluation of the work as a whole. It details my approach to Catholicism, paganism, transgender identity, and oppression. My work grapples with both my current understanding of myself and my inability to enunciate my reality in the past. I aim to view divinity and personal history through a lens of queerness.

Advisor: Kwame Dawes

Virion Composition Of Wheat Streak Mosaic Virus (Wsmv) And Its Use As An Expression Vector, Sourav Pal

Department of Plant Pathology: Dissertations, Theses, and Student Research

Wheat (Triticum aestivum L.) is the principal cereal grown in the United States, whose production ranks third in the world. Bacterial leaf streak (BLS) disease caused by Xanthomonas translucens pv. undulosa (xtu) is an emerging threat to wheat production in the Great Plains region of the United States of America. In this study, we engineered sequences encoding several plant-based antimicrobial peptides (AMP) were engineered into the WSMV genome and examined their effect on BLS disease in wheat infected by WSMV harboring AMP sequences. Out of nine AMPs, wheat expressing Ace-AMP1, PDF13, TK-AMP-D1, and TK-AMP-D3 produced resistance against the …

Transforming Grassland Conservation: Challenges And Opportunities Across Law, Policy, And Human Dimensions, Conor D. Barnes

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Great Plains social-ecological systems are facing growing pressure from complex, ‘wicked’ problems. Addressing these problems will require integrating ecological resilience and complex systems thinking concepts into our legal framework in order to better reflect the changing ecological reality of the Great Plains and promote flexibility and adaptability in the face of that change. In this dissertation, I examine how past and present policy priorities have affected social-ecological systems on the Great Plains, and how ecological resilience and complex systems thinking might be applied to grassland management policy. In Chapter 2, I examine the rapid progress made in the adoption of …

Further Developing Drought Early Warning Information Systems Using Mixed-Methods And Multiple Streams Of Data, Caily Claire Schwartz

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Drought is a complex phenomenon with varying degrees of impacts and monitoring methods. No drought is alike, creating a challenge for both water managers and communities. No area is immune to a drought. Due to the cyclical nature of drought events, clear information to those impacted is necessary to reduce risk and move towards proactive responses, as opposed to reactive responses. To better provide communication and mitigation tools, Drought Early Warning Information Systems (DEWIS) have been developed in various regions and contexts. To improve early warning, an understanding of the end user’s perceptions of risk, and the applicability of data …

Development Of Feature Extraction Models To Improve Image Analysis Applications In Cancer, Yu Shi

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Cancer poses a significant global health challenge. With an estimated 20 million new cases diagnosed worldwide in 2022 and 9.7 million fatalities attributable to the disease, the economic burden of cancer is immense. It impacts healthcare systems and imposes substantial costs for its care on patients and their families. Despite advancements in early detection, prevention, and treatment that have reduced overall cancer mortality rates, the growing prevalence of cancer, particularly among younger individuals, remains a pressing issue.

Recent advancements in medical imaging technology have progressed significantly with the help of emerging computer vision and artificial intelligence (AI) technology. Despite these …

A Study On The Vanishing Of Ext, Andrew J. Soto Levins

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This thesis has two goals. The first is to study an Ext analog of the rigidity of Tor, and the second is to study Auslander bounds.

In Chapter 2 we show that if R is an unramified hypersurface, if M and N are finitely generated R-modules, and if the nth Ext modules of M against N is zero for some n less than or equal to the grade of M, then the ith Ext module of M against N is zero for all i less than or equal to n. A corollary of this says that if …

Semigroup Well-Posedness And Finite Element Analysis Of A Biot-Stokes Interactive System, Sara Mcknight

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The coupling of a porous medium modeled by the Biot equations and a fluid has many biological applications. There are numerous ways by which to model the fluid and to couple the porous medium with the fluid. This particular model couples the Biot equations to Stokes flow along the boundary, through the Beavers-Joseph-Saffman conditions. We address semigroup well-posedness of the system via an inf-sup approach, which along the way requires consideration of a related but uncoupled static Biot system. We also present the results of finite element analysis on both the uncoupled Biot system and the coupled system.

Advisor: Sara …

Investigation Of Faults In Air-Conditioning Systems In Commercial Buildings: Occurrence, Diagnostic Validation, And Energy Impacts, Yuxuan Chen

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

In commercial buildings, fault detection and diagnosis (FDD) tools have been developed for detecting and diagnosing faults in building systems, which can provide useful information regarding fault locations and potential causes of faults, so that building operators and facility staff can be notified in time and quickly respond as problems arise. Nowadays, there are many commercial FDD tools available in the market, and these tools have been widely adopted in large- and medium-scale commercial buildings in the United States. Several studies have demonstrated the energy saving potential with the use of FDD in commercial HVAC systems, and one critical aspect …

Integrating Water And Nitrogen Management For Sustainable Agriculture: Optimizing Resource Use Efficiency And Maximizing Crop Productivity, Jiaming Duan

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Advisors: Derek Heeren and Daran Rudnick Maize, accounting for over 95% of national grain production in the United States, is highly sensitive to water and nitrogen (N) inputs. Conventional agricultural practices often lead to excessive application, causing groundwater contamination through nitrate leaching. Therefore, there is a demand for integrating water and nitrogen management with innovative scheduling methods for sustainable agricultural development.

This dissertation first reviewed two decades of U.S.-based research, highlighting the optimal management of water and N to enhance yield, water use efficiency (WUE), and nitrogen use efficiency (NUE). Findings indicate that maintaining optimal levels of N and water …

"I Will Write Mad Stories": The Hysterical "I" In The Diaries Of George Eliot, Charlotte Forten Grimke, Virginia Woolf, And Sylvia Plath, Jaclyn Marie Swiderski

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation focuses on the long history of hysteria and the ways in which it has been used to denigrate and silence disabled women. Women diagnosed as hysterical, by either the medical establishment or the court of public opinion, are denied the right to generate knowledge about and for themselves – they are epistemologically disabled. The author argues that hysterical women have unique ways of looking at and understanding the world which push back against their epistemological disablement. In order to uncover some of this history of hysterical women, this dissertation uses the diaries of four “hysterical” women over the …

A Data-Driven Discovery System For Studying Extracellular Microrna Sorting And Rna-Protein Interactions, Sasan Azizian

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Interactions between microRNAs (miRNAs) and RNA-binding proteins (RBPs) are pivotal in miRNA-mediated sorting, yet the molecular mechanisms underlying these interactions remain largely understudied. Few miRNA-binding proteins have been verified, typically requiring extensive laboratory work. This study introduces DeepMiRBP, a novel hybrid deep learning model designed to predict microRNA-binding proteins. The model integrates Bidirectional Long Short-Term Memory (Bi-LSTM) networks with attention mechanisms, transfer learning, and cosine similarity to offer a robust computational approach for inferring miRNA-protein interactions.

DeepMiRBP is implemented through two distinct architectures. The first architecture employs a Y-shaped model that uses Bi-LSTM networks and transfer learning to extract contextual …

Long Term Ultrasonic Monitoring And Machine Learning Investigation Of Micro-Crack Damaged Concrete, Yalei Tang

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The thermal modulation method is a recently developed nonlinear ultrasonic technique for evaluating material damage. This method utilizes thermal strain changes resulting from temperature variations to excite the nonlinear behavior of materials and modulate high-frequency ultrasonic waves within them. Its working principle suggests significant potential for application in large-scale concrete structures and in-situ monitoring of real structures. Despite numerous laboratory demonstrations of its effectiveness, several gaps remain before it can be applied to in-service large concrete structures.

This study investigates the potential of the thermal modulation technique for evaluating concrete structures in ambient conditions, addressing key uncertainties for practical implementation. …