Physical Sciences and Mathematics Commons^™

Investigation Of The Chemical And Electronic Structure Of A 2h Phase Mos2 Single Crystal, Mary Blankenship

UNLV Theses, Dissertations, Professional Papers, and Capstones

Molybdenum disulfide has a wide range of applications in energy conversion devices, like thin-film solar cells, batteries, bio sensors, and more. Although the properties of MoS2 and other transition metal dichalcogenides (TMDC) have been widely studied, disagreements and discrepancies regarding its electronic structure remain.

In this thesis, a highly-oriented synthetic 2H phase MoS₂ single crystal is investigated using a toolchest of spectroscopic techniques to uncover its chemical and electronic properties. Lab-based x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), inverse photoemission spectroscopy (IPES), and low energy electron diffraction (LEED) were performed at UNLV and combined with resonant inelastic soft …

Travel Time Theory For Traffic Conservation Laws With Applications, Sergio Contreras

UNLV Theses, Dissertations, Professional Papers, and Capstones

Travel time is an important concept in various intelligent transportation system (ITS) applications. The concept is used in a wide array of applications, such as system planning, system performance, and optimization. Reducing the time required to travel between different points on a network is an important goal. Benefits include reducing time wasted in traveling, and keeping travelers satisfied. Thus, studying and reducing travel time in ITS is beneficial in different applications.

The classic density-based Lighthill Whitman Richards (LWR) equation for modeling traffic flow is the starting point in this dissertation. A more recent travel time dynamics function built on top …

Examining Covid-19 Vaccine Hesitancy Among The Nevada African American Population Using The Social-Ecological Model, Katelyn Faulk

UNLV Theses, Dissertations, Professional Papers, and Capstones

In Nevada, COVID-19 vaccines have been widely available to the general population since March 2021; however, even with the wide availability of these vaccines only 40% of the African American population in Nevada has been fully vaccinated against COVID-19 as of May 2023. This is problematic as it has been shown that the African American population is disproportionately affected by COVID-19 with higher rates of cases, hospitalizations, and deaths when compared to other races or ethnicities. Through the literature, it has also been well documented that African Americans may experience hesitancy toward these vaccinations for a multitude of reasons including …

Scalable Algorithm Design And Performance Analysis For Graph Motifs Discovery, Md Abdul Motaleb Faysal

UNLV Theses, Dissertations, Professional Papers, and Capstones

Discovering motifs or structural patterns, such as communities, is a significant graph application utilized for classifying groups in social and business networks, identifying similar proteins, detecting anomalous behavior in the cybersecurity domain, and finding critical entities in rumor propagation or infectious disease spreading. Existing state-of-the-art techniques for community discovery face challenges related to scalability, performance limitations, and methodological inaccuracies. The objective of this doctoral dissertation is to introduce novel parallel algorithms and propose high-performance computing architecture designs to address the performance constraints of current community detection approaches when processing large-scale social and biological data. This research focuses on two main …

An Evaluation Of Lead Concentration In Commercially Available Tiles, Daidre N. Gamboa

UNLV Theses, Dissertations, Professional Papers, and Capstones

Workers in the manufacturing and construction industries are at risk of lead exposure in projects that involve removal or installation of tiles, and other individuals exposed to lead, including children may also be at risk. The concern with lead in tiles is thought to be related to the glazing process or the country where the tile was produced. Multiple regulations are in place in the U.S. to protect people from lead exposure, including through surface coatings or painted surfaces. But these regulations do not cover glazed tiles. This study examined whether there are differences in lead concentration in (1) tiles …

Investigating A Passive Treatment System For The Removal Of Nutrients From Urban Runoff, Jasminn Gray

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Environmental Protection Agency recognizes urban runoff as a major contributor of surface water pollution with nutrients as the second largest cause of surface water impairment in the United States. While a water quality standard of 100 lbs/day total phosphorus load allocation for all nonpoint sources is permitted for the Las Vegas Valley (LVV) under the National Pollutant Discharge Elimination System, currently there is not a counterpart standard for nitrogen. With the continued development of the LVV and the depletion of the quantity of water in Lake Mead due to the ongoing drought, the concentrations of phosphorus and nitrogen species …

The Room Temperature Electrolysis Of F-Elements In Aqueous And Ionic Liquid Media: Synthesis, Dissolution, And Reduction, Phillip George Hammer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Procuring F-element metals is no simple task and often requires the use of caustic and hazardous materials at high temperatures. These materials are invaluable for a variety of scientific missions ranging from the elucidation of fundamental properties, as fast spectrum nuclear fuel forms, to pit production modernizing our nuclear stockpiles. Metallic actinide materials are essential to strategic and critical materials recovery, the nuclear energy sector, and weapons production. Room temperature electrolysis is envisioned as a process to recover laboratory scale (milligram to gram) quantities of actinide metals. This process closes the uranium chemical loop allowing the reclamation of materials for …

The Impact Of The Covid-19 Pandemic Response On Food Safety Violations Observed In Southern Nevada Food Establishments, Samantha Morales

UNLV Theses, Dissertations, Professional Papers, and Capstones

Food poisoning is a common term used to describe what is actually foodborne illness. Despite the fact these illnesses can become deadly, foodborne illnesses are endemic and common in the United States. Nonetheless, they are completely preventable simply by following proper food safety procedures. The Food and Drug Administration identified the most common foodborne pathogens responsible for most foodborne infections, as well as the five risk factor categories to target in order to decrease the risk of cases and outbreaks.

To ensure foodborne outbreaks and cases are prevented, health authorities are tasked with conducting routine inspections on permitted food establishments. …

Examining The Spatial Periodicity Of Force Chains And Strain Localization In Polycrystal Models, Richard D. Panduro-Allanson

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shear strain localization is typical in deforming rocks and is vital for developing faults and tectonic boundaries. There are various proposed drivers of shear localization (temperature, fluid, phase transformation, and microstructure); we will explore the effects of elastic heterogeneity (a microstructural influence) on shear localization in polycrystal models. Elastic heterogeneity can lead to varied stress states in material and drive shear localization. Previous simulations of elastically heterogeneous polycrystal models have shown that the stress distribution can be described as forming an anastomosing pattern of high-stress streams parallel to the compression direction. This anastomosing patterning resembles force chains; linear, high-stress features …

Implementation Of Adas And Autonomy On Unlv Campus, Zillur Rahman

UNLV Theses, Dissertations, Professional Papers, and Capstones

The integration of Advanced Driving Assistance Systems (ADAS) and autonomous driving functionalities into contemporary vehicles has notably surged, driven by the remarkable progress in artificial intelligence (AI). These AI systems, capable of learning from real-world data, now exhibit the capability to perceive their surroundings via a suite of sensors, create optimal routes from source to destination, and execute vehicle control akin to a human driver.

Within the context of this thesis, we undertake a comprehensive exploration of three distinct yet interrelated ADAS and Autonomy projects. Our central objective is the implementation of autonomous driving(AD) technology at UNLV campus, culminating in …

Actinide Behavior In Soft Ligand Environments And Higher Oxidation States Of Neptunium In Aqueous Media With Solid-State Synthesis Of Np(Vii) Compounds, Kelly Floyd Seeley

UNLV Theses, Dissertations, Professional Papers, and Capstones

The fundamental properties of Uranium and Neptunium were investigated with Powder X-Ray Diffraction (PXRD) to study the behavior or 5f electrons with chalcogen, alkali metals, and alkaline earth metals. Two novel compounds were generated: NaCuUS₃ and NaCuNpS₃. There are several crystal structures that form in the family of AMM’Q (A = s-block, M = d-block, M’ = d-block or f-block, and Q = chalcogen), with oxidation states of A¹⁺, M¹⁺, M’⁴⁺, and Q^2- ions from the family of type I compounds. Work was continued to …

Waste To Value: Global Perspective On The Impact Of Entomocomposting On Environmental Health, Greenhouse Gas Mitigation And Soil Bioremediation, Dennis Beesigamukama, Chrysantus M. Tanga, Subramanian Sevgan, Sunday Ekesi, Segenet Kelemu

All Peer-Reviewed Publications

The innovative use of insects to recycle low-value organic waste into value-added products such as food, feed and other products with a low ecological footprint has attracted rapid attention globally. The insect frass (a combination unconsumed substrate, faeces, and exuviae) contains substantial amounts of nutrients and beneficial microbes that could utilised as fertilizer. We analyse research trends and report on the production, nutrient quality, maturity and hygiene status of insect-composted organic fertilizer (ICOF) generated from different organic wastes, and their influence on soil fertility, pest and pathogen suppression, and crop productivity. Lastly, we discuss the impact of entomocomposting on greenhouse …

Perception Of Bias In Chatgpt: Analysis Of Social Media Data, Abdullah Wahbeh, Mohammad A. Al-Ramahi, Omar El-Gayar, Ahmed El Noshokaty, Tareq Nasralah

Computer Information Systems Faculty Publications (Archived)

In this study, we aim to analyze the public perception of Twitter users with respect to the use of ChatGPT and the potential bias in its responses. Sentiment and emotion analysis were also analyzed. Analysis of 5,962 English tweets showed that Twitter users were concerned about six main types of biases, namely: political, ideological, data & algorithmic, gender, racial, cultural, and confirmation biases. Sentiment analysis showed that most of the users reflected a neutral sentiment, followed by negative and positive sentiment. Emotion analysis mainly reflected anger, disgust, and sadness with respect to bias concerns with ChatGPT use.

Influence Of Pavement Conditions On Commercial Motor Vehicle Crashes, Stephen Arhin, Babin Manandhar, Adam Gatiba

Mineta Transportation Institute

Commercial motor vehicle (CMV) safety is a major concern in the United States, including the District of Columbia (DC), where CMVs make up 15% of traffic. This research uses a comprehensive approach, combining statistical analysis and machine learning techniques, to investigate the impact of road pavement conditions on CMV accidents. The study integrates traffic crash data from the Traffic Accident Reporting and Analysis Systems Version 2.0 (TARAS2) database with pavement condition data provided by the District Department of Transportation (DDOT). Data spanning from 2016 to 2020 was collected and analyzed, focusing on CMV routes in DC. The analysis employs binary …

Trashed: A Review Of Anthropogenic Litter In An Urban Watershed, John D. Hamilton

Water Resources Science and Technology Theses and Graduate Research Reports (Archived)

Urban creeks, streams and rivers have become an unfortunate destination for trash pollution. Within an urban watershed trash pollution is harmful to fish, wildlife, public health, contributes to microplastic proliferation, and aesthetically tarnishes an otherwise unscathed ecosystem. With lots of attention focused on trash in marine and coastal ecosystems, this study aims to contribute to the growing research on inland urban watersheds and their involvement. This study highlights issues associated with trash pollution, and investigates the associated vectors, origins, behaviors, and contributing factors that create trash ladened urban watersheds. Datasets and site surveys from repeated trash cleanups in three creekside …

A Control Study Analysis Application Of Unoccupied Aerial Systems (Drones) To Monitor Eutrophication, Chrystal Mata

Water Resources Science and Technology Theses and Graduate Research Reports (Archived)

Unmanned Aircraft systems (UAS) can offer a valuable perspective for detecting and monitoring for eutrophication in bodies of water by providing high-resolution images and data assignments for algal blooms and nutrient levels. Eutrophication, the process by which water bodies become enriched with nutrients, has emerged as a critical factor in evaluating and maintaining water quality. In this study, we use DJI Inspire Pro 1 equipped with a Zenmuse X3 camera, attached with a Parrot Sequoia multispectral sensor was used to in conjunction with algorithms to retrieve Chlorophyll parameters for monitoring eutrophication. Although water quality parameters such as pH, nitrate, phosphate, …

Qasm-To-Hls: A Framework For Accelerating Quantum Circuit Emulation On High-Performance Reconfigurable Computers, Anshul Maurya

Theses and Dissertations

High-performance reconfigurable computers (HPRCs) make use of Field-Programmable Gate Arrays (FPGAs) for efficient emulation of quantum algorithms. Generally, algorithm-specific architectures are implemented on the FPGAs and there is very little flexibility. Moreover, mapping a quantum algorithm onto its equivalent FPGA emulation architecture is challenging. In this work, we present an automation framework for converting quantum circuits to their equivalent FPGA emulation architectures. The framework processes quantum circuits represented in Quantum Assembly Language (QASM) and derives high-level descriptions of the hardware emulation architectures for High-Level Synthesis (HLS) on HPRCs. The framework generates the code for a heterogeneous architecture consisting of a …

Chemical Investigation Of Dichloromethane Extract Of Aloe Vera Peels: An Agricultural Waste, Nazmul Huda

Theses and Dissertations

Aloe barbadensis Miller, commonly called Aloe Vera, is a widely popular succulent plant species cultivated across subtropical regions worldwide from India to the Tex-Mex border. Besides its historical uses, Aloe juice has garnered attention as a potential remedy for various ailments, particularly in treating various skin conditions and facilitating wound recovery, including obesity, diabetes, hepatitis, Crohn's disease, and ulcerative colitis. Regrettably, the agricultural practice following sap extraction involves discarding Aloe vera peels, constituting agricultural waste. As part of our continuous research on extraction, isolation, separation, and spectral characterization of value-added chemicals present in waste botanicals herein, …

Experimental Analysis Of Nonlinear Wave Propagation In Bistable Mechanical Metamaterials With A Defect, Samuel R. Harre

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Mechanical metamaterials built up of compliant units can support the propagation of linear and nonlinear waves. A popular architecture consists of a one-dimensional chain of bistable elements connected by linear springs. This type of chain can support nonlinear transition waves that switch each element from one stable state to the other as they propagate along the chain. One way to manipulate the propagation of such waves is via introduction of a local inhomogeneity, i.e., a defect in the otherwise periodic chain. Recent analytical and numerical work has shown that based on its initial velocity, a transition wave may be reflected, …

On Dyadic Parity Check Codes And Their Generalizations, Meraiah Martinez

Department of Mathematics: Dissertations, Theses, and Student Research

In order to communicate information over a noisy channel, error-correcting codes can be used to ensure that small errors don’t prevent the transmission of a message. One family of codes that has been found to have good properties is low-density parity check (LDPC) codes. These are represented by sparse bipartite graphs and have low complexity graph-based decoding algorithms. Various graphical properties, such as the girth and stopping sets, influence when these algorithms might fail. Additionally, codes based on algebraically structured parity check matrices are desirable in applications due to their compact representations, practical implementation advantages, and tractable decoder performance analysis. …

Interaction Of Technetium (Iv) With Dibutyl Phosphate In N-Dodecane, Jonathan George

UNLV Theses, Dissertations, Professional Papers, and Capstones

During the reprocessing of nuclear fuel, the degradation of tributylphosphate (TBP) occurs as a result of radiolytic and thermal processes. These processes lead to the formation of minor amounts of dibutyl phosphate (HDBP). However, the presence of DBP poses a challenge in the partitioning of uranium (U), plutonium (Pu), and technetium (Tc) due to its chelating effects. The chelation of these elements by HDBP can interfere with their intended separation and purification, thereby impacting the efficiency and effectiveness of the reprocessing process. In this study, X-ray Absorption Fine Structure (XAFS) spectroscopy is employed to investigate the speciation of Tc following …

New Observations On The Age And Origin Of The Geologist Seamounts, South Hawaiian Seamount Province, Brandon Chester Scott

UNLV Theses, Dissertations, Professional Papers, and Capstones

Investigation into seamounts that stem from intraplate volcanism—that is volcanism occurring far from plate boundaries—presents an opportunity to deconvolve processes associated with mantle compositional heterogeneities and melting dynamics. Upwelling and decompression of thermochemically anomalous mantle plumes is the primary mechanism for significant intraplate volcanism; however, many seamounts dotted across the Pacific Plate do not correlate spatially, temporally, or geochemically with mantle plume volcanism. One region of enigmatic volcanism in the ocean basins that is not clearly attributable to plume-derived magmatism are the Geologist Seamounts and the wider South Hawaiian Seamount Province (∼19°N, 157°W). Here we present merged multibeam (<100 m) and satellite altimetry bathymetric maps of the Geologist Seamounts region, new ^{40 …}

Bridging The Gap: Analyzing The Relationship Between Environmental Justice Awareness On Twitter And Socio-Environmental Factors Using Remote Sensing And Big Data, Charles Knoble, Danlin Yu

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Mounting awareness of the discriminatory distribution of environmental factors has increasingly placed environmental justice at the forefront of discussions on sustainable development, but responses to these disparities are often too little, too late. Remote sensing has emerged as a potential solution to this problem, capitalizing on the ability to capture high-resolution, spatially explicit data in near-real time. However, a conventional reliance on physical measurements and surface-level analyses risks overlooking the experiences and perceptions of affected communities. It is against this backdrop that the potential integration of remote sensing imagery and socially sensed big data such as social media data assumes …

Electrodeposition Studies Of Gold Nanoparticles And Alginate Hydrogel Films., Harikrishnan Nambiathan Nambiar

Electronic Theses and Dissertations

This dissertation investigates the electrochemical deposition (ECD) and electrophoretic deposition (EPD) processes involving citrate (cit)-stabilized Au nanoparticles (NPs) and calcium alginate (Ca-Alg-Au NP) hydrogel films. The first part of the dissertation investigates the influence of NP size, surface area (SA) coverage, and ligand stabilizers on the electrochemical growth of Au on Au NPs, aiming to enhance our understanding of the growth process during the nucleation and growth of metal NPs. The growth kinetics depend on Au NP size (4 nm > 15 nm > 50 nm) for a constant SA coverage, as determined by the overpotentials for ECD. The growth rate increases …

Perovskite Oxide Derivatives For Enhanced Electrochemical Water Splitting And Pseudocapacitor Applications., Md. Sofiul Alom

Electronic Theses and Dissertations

The global energy landscape is at a crossroads, marked by surging demand, finite fossil fuel reserves, and escalating environmental concerns stemming from carbon emissions. To address these challenges and transition towards a sustainable energy future, this dissertation embarks on a multidisciplinary exploration of perovskite oxides and their derivatives as catalysts and materials for advanced electrochemical water splitting and pseudocapacitive energy storage. In the quest for efficient water splitting catalysts, a series of quasi-2D oxides, SrLaAl_1/2M_1/2O₄ (M = Mn, Fe, Co), was synthesized and systematically studied where the B-site comprised of both transition metals and main …

Effects Of A Protection Zone In A Reaction-Diffusion Model With Strong Allee Effect., Isaac Johnson

Electronic Theses and Dissertations

A protection zone model represents a patchy environment with positive growth over the protection zone and strong Allee effect growth outside the protection zone. Generally, these models are considered through the corresponding eigenvalue problem, but that has certain limitations. In this thesis, a general protection zone model is considered. This model makes no assumption on the direction of the traveling wave solution over the Strong Allee effect patch. We use phase portrait analysis of this protection zone model to draw conclusions about the existence of equilibrium solutions. We establish the existence of three types of equilibrium solutions and the necessary …

Scalable Solution Processing Of Niox Nanoparticles., Peter James Armstrong

Electronic Theses and Dissertations

Perovskite solar cells (PSCs) are a promising alternative to silicon-based photovoltaics. However, PSCs face several challenges due to shortcomings in their stability, module efficiency, and scaled production. Although PSCs is still a young field of research, significant attention has been given to demonstrating power conversion efficiencies that are on par with traditional silicon. With that target reached, converting the laboratory demonstration into practical materials to increase access and abundance of solar energy are among the next large targets for the field. This comes with material challenges for perovskite and their companion charge transport layers (CTLs). Among the charge transport materials …

Causal Inference For The Effect Of Continuous Treatment On Time-To-Event Outcomes And Mediation Analysis On Health Disparities In Observational Studies., Triparna Poddar

Electronic Theses and Dissertations

The dissertation comprises two projects related to causal inference based on observational data. In healthcare research, where abundant observational data such as claims data and electronic records are available, researchers often aim to study the treatment effect and the pathway of that effect. However, estimating treatment effects in observational data presents challenges due to confounding factors. The first project focuses on estimating continuous treatment effects for survival outcomes, while the second concentrates on mediation analysis, allowing the exploration of the pathway of the causal effect. Both projects involve addressing confounding variables. In the first project, I investigate estimation of the …

Computational Investigations Of Bond Breaking Processes Using Dft And Td-Dft Approaches., Saurav Parmar

Electronic Theses and Dissertations

The efficient application of DFT and TD-DFT has been harnessed to study bond-breaking processes in some molecules which play a prominent role in enzymatic reactions. The first application includes Radical S-adenosyl methionine (SAM) enzymes which are fundamentally important sources of organic radicals to initiate diverse radical reactions. Recently a bio-organometallic intermediate (Ω) that contains an Fe‒C bond has been characterized and shown to be a common feature of radical SAM enzymes. The strength of Fe‒C bond in Ω has been computed using broken-symmetry density functional theory (BS‒DFT). Additionally, Fe‒C bond dissociation energy (BDE) in Ω has been compared to that …

The Self-Consistent Field Energy Landscape And Its Application To Describing Electron Correlation., Xinju (Spancer) Dong

Electronic Theses and Dissertations

Global elucidation of SCF (self-consistent-field) solutions is an extension of global optimization in which the goal is the identification of all solutions, which can be defined as a NP (nonpolynomial)-hard problem. The value of identifying multiple SCF solutions is to use as reference wavefunctions, such as NOCI (nonorthogonal configuration interactions), NOMCSCF (nonorthogonal multiconfigurational SCF), etc. However, the high-dimensional space over which to search and the relatively high cost of local optimization in Hartree-Fock (HF) models cause difficulty in efficiently searching over the full SCF space. In order to address the technical issues of high-dimensionality and nonlinearity, a Lie algebraic description …