Physical Sciences and Mathematics Commons^™

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 …

Investigating Van Der Waals Josephson Junctions With 2h-Nbse2 And 1t’-Wte2, Kristine Lorraine Haley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Josephson junctions have garnered significant attention due to their unique electronic properties and applications in quantum devices. In this thesis, we investigate the fabrication processes and characterization of two-dimensional (2D) Josephson junctions consisting of layered van der Waals materials: niobium diselenide (2H-NbSe2) and few layered tungsten ditelluride (1T’-WTe2). The reduction of dimensionality can bring forth unique characteristics in certain materials that are not seen in their bulk counterparts, making them prime candidates for physical exploration. 2H-NbSe2 is an s-wave superconductor at temperatures near and below 7 K. 1T’-WTe2 is a semimetal in bulk but is an intrinsic quantum spin Hall …

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 x-ray …

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 …

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 Q2- ions from the family of type I compounds. Work was continued to generate the double perovskite structures in soft donor ligand environments, along with the double perovskite …

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 40Ar/39Ar age determinations, and major and trace element geochemistry for six remote-operated vehicle recovered igneous rock samples (NOAA-OER EX1504L3) and two dredged samples (KK840824-02) from the Geologist Seamounts. The new ages indicate volcanism was active from 89–86 Ma and 73–72 Ma, inferring that, in conjunction with previous ages of ~83 Ma, seamount emplacement initiated near the paleo Pacific-Farallon spreading ridge and volcanism continued for at least a ~17 Ma period. Geochemical analyses indicate that Geologist Seamounts lava flows are highly alkalic and represent low-degree partial mantle melts primarily formed from a mixture of melting within the garnet and spinel stability field prior to eruption. Using the new age and chemical constraints three separate formation models for the Geologist Seamounts are tested: (1) a mantle-plume derived origin, (2) a shear-driven upwelling origin, and (3) a lithospheric extension origin. The ages and morphological characteristics infer the seamounts were likely not related to the Euterpe Plume (Musician Seamounts) or a different extinct plume. Shear driven upwelling cannot account for ~17 Ma of volcanism in a limited geographic region, nor for the oblique orientation of Geologist Seamounts relative to paleo spreading direction as shear driven upwelling forms seamount chains mirroring the direction of crustal spreading. Lastly, we build upon previous models that local microblock formation and rotation corresponded with regional lithospheric extension and the formation of the Geologist Seamounts. Using available multibeam bathymetry and magnetic reversal data, we propose the microblock was bounded by the Molokai and short-lived Kana Keoki Fracture Zones. Regional deformation and corresponding volcanism among the Geologist Seamounts associated with the microblock potentially occurred in pulses contemporaneous to independently constrained changes in Pacific Plate motion vectors at ca. 85 and 75 Ma—indicating that major changes in plate vectors can generate intraplate volcanism.

On The Synthesis Of Heavy Rare Earth Solid Solutions And Their Hydrides, Joshua R. Van Cleave

UNLV Theses, Dissertations, Professional Papers, and Capstones

The theoretical predictions and results from the (La,Y)Hx ternary hydride solution provided evidence toward phase stability at comparatively lower pressures, as consequence the (Yb,Lu)Hx and (Tm,Lu)Hx ternary hydrides are studied here with pressures up to 25 GPa in the diamond anvil cell. The onset of an unknown feature in the XRD pattern coincides with crystallographic plane distortions in the tetragonal lattice of ytterbium hydride at their laser-heated interface, possibly driven by a solid solution of Lu-Yb. Findings in collected Raman spectra and X-ray diffraction patterns in an Ar environment suggest potential stability of the FCC and high-temperature HCP phases of …

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 …

Beyond Corporate Greenwashing: Discourse Of A Just Electric Energy Transition Materialized At The Thacker Pass Lithium Mine, Laekyn Kelley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Thacker Pass in Northern Nevada is a rich desert ecosystem with spiritual significance to local Indigenous peoples, and it is also the site for what will be, for now, the United States’ largest open-pit lithium mine. Lithium is one mineral constituent of electric batteries which are essential to current U.S. electric energy transition policy, a transition which policymakers and other public groups have called on to be done in a way which is just. However, what exactly a just electric energy transition looks like in places like Thacker Pass is under continued negotiation in theoretical and practical senses. Existing research …

Development, Voice, And Vulnerability: A Rhetorical Analysis Of The Policy-Making Discourse Regarding The Paris Agreement As An Organizational Response To Climate Change, David Almanza-Canas

UNLV Theses, Dissertations, Professional Papers, and Capstones

On December 12, 2015, the Paris Agreement was officially ratified by 196 sovereign entities. This treaty represents a global call to action to ameliorate the impact of human activities on our environment, and it creates a means of cooperation through financial support and transparent industrial practices with the goal of promoting accountability across the world. This treaty and the discourse surrounding it present fertile ground for the academic understanding of persuasive practices in policy-making. By examining the rhetorical implications of the Paris Agreement as a global policy, scholars can gain new insight about the communities represented in the conversation as …

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 …

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 …

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 of …

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 …

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 …

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. In …

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 …

Water Efficiency & Sustainability In The Mountain West, 2022, Zachary Billot, Caitlin J. Saladino, William E. Brown Jr.

Environment

This fact sheet analyzes the effectiveness of state-level policies related to water usage, conservation, and sustainability for the Mountain West states of Arizona, Colorado, Nevada, New Mexico, and Utah in 2022. The original data are published in the “2022 State Policy Scorecard for Water Efficiency and Sustainability” report written by the Alliance for Water Efficiency.

The High Pressure Dependence Of X-Ray Induced Decomposition Of Cadmium Oxalate, Adrian F. Lua Sanchez, Petrika Cifligu, Marc Graff, Michael Pravica, Pradip K. Bhowmik, Changyong Park, Egor Evlyukhin

Physics & Astronomy Faculty Research

The high proclivity of x rays to destabilize and distort molecular structures has been previously utilized in the synthesis of novel compounds. Here, we show that x-ray induced decomposition of cadmium oxalate induces chemical and structural transformations only at 0.5 and 1 GPa. Using x-ray diffraction and Raman spectroscopy, the synthesized product is identified as cadmium carbonate with cadmium oxalate remnants, which is stable under ambient conditions. At ambient and >1 GPa pressures, only degradation of the electronic density distribution is observed. The transformation kinetics are examined in terms of Avrami’s model, which demonstrates that despite the necessity of high …

Evocative And Provocative Image-Making In The Age Of Generative Ai, Julian Kilker

Tradition Innovations in Arts, Design, and Media Higher Education

Editorial for inaugural AI-focused special issue of Tradition-Innovations in Arts, Design, and Media Higher Education, published under the auspices of the Alliance for the Arts in Research Universities (a2ru). Discusses three articles by five authors in this issue: (1) Choreographing Shadows: Interdisciplinary collaboration to orchestrate ethical image-making by Mark Burchick and Diana Pasulka; (2) Giving Up Control: Hybrid AI-augmented workflows for image-making by Joshua Vermillion; and (3) Hands are Hard: Unlearning how we talk about machine learning in the arts by Adam Hyland and Oscar Keyes.

Editing this special issue explored several key questions: What does “innovation” mean when …

Broadband Equity, Access, And Deployment In Nevada, Brad Wimmer

Policy Briefs and Reports

The $45.45 billion Broadband, Equity, Access, and Deployment (BEAD) program’s primary objective is to extend broadband service to all unserved and underserved locations in the U.S. and its territories. Several industry studies predict that the BEAD program can meet its goal of providing universal access to broadband service if eligible entities execute their grant programs well. My review of the BEAD program indicates that policy makers can enhance the likelihood of program success by designing competitive grant programs that give applicants the incentive to undercut the subsidies proposed by their rivals and provide applicants the flexibility to design networks that …

Ocr Post-Processing Using Large Language Models, Mahdi Hajiali

UNLV Theses, Dissertations, Professional Papers, and Capstones

Optical Character Recognition (OCR) technology transforms textual visuals into an electronically readable, non-graphical format of the text. This allows the editing and other text manipulation of the content by language technology software such as machine translation, text comprehension, query-answering systems, and search engines. While Optical Character Recognition (OCR) systems continually progress towards greater precision, several complications persist when dealing with low-resolution source images or those with multicolored backgrounds. Consequently, the text derived from OCR necessitates additional refinement to optimize accuracy, beneficial for various subsequent applications. It is recognized that the character accuracy of OCR-generated text may influence certain natural language …

Environmental And Socio-Economic Stress In The Mountain West, Ayda Atici, Caitlin J. Saladino, Fatma Nasoz, William E. Brown Jr.

Environment

This fact sheet examines data on environmental and socio-economic risk metrics including which metrics pose the most risk for Nevada counties.The data are retrieved from “System for the Triage of Risks from Environmental and Socio-Economic Stressors” created by the Massachusetts Institute of Technology (MIT) joint program on the science and policy of global change.

Depression, Anxiety, And Estimated Cardiorespiratory Fitness In College Students, Christian Ison

UNLV Theses, Dissertations, Professional Papers, and Capstones

Depression and anxiety disorders are two common mental health conditions worldwide. College students are considered a high-risk population for the development of these conditions. Improved cardiorespiratory fitness (CRF) has been shown to decrease depression and anxiety risk, symptoms, and severity but this relationship and the extent to which improved CRF can reduce these risks has yet to be examined in the college student population. Validated and reliable non-exercise estimated cardiorespiratory fitness (eCRF) algorithms could be used to identify relationships and associations with depression and anxiety severity levels among college students. The purpose of this study was to assess eCRF and …

Magmatic Processes Leading To Compositional Diversity In The Mars Crust, Amanda Marie Ostwald

UNLV Theses, Dissertations, Professional Papers, and Capstones

The ancient Mars crust can yield insights into planet formation and evolution that Earth cannot. Direct investigation of the martian surface is limited to studies on meteorites and rover-obtained analyses. The nakhlites and chassignites, two classes of martian meteorites, are together the largest suite of martian meteorites derived from a single location on the surface. As such, they present a rare opportunity to study the Mars crust in detail using samples bearing a contextual relationship. Rover studies have found a surprising amount of compositional diversity in surface materials, the formation mechanisms of which are not well-constrained. This dissertation leverages meteorites …

Facial Expression Recognition Using Convolutional Neural Networks (Cnns) And Generative Adversarial Networks (Gans) For Data Augmentation And Image Generation, Shekhar Singh

UNLV Theses, Dissertations, Professional Papers, and Capstones

Facial expressions play a crucial role in human communication, serving as a powerful means to convey emotions. However, classifying facial expressions using artificial intelligence (AI) can be challenging, especially with small datasets and images. Facial Expression Recognition (FER) is an active area of research, with Convolutional Neural Networks (CNNs) being widely employed for classification. In this research, we propose a CNN-based approach for FER that utilizes both original and augmented datasets to enhance classification accuracy. Experimental results on the FER2013 dataset show test accuracies of 63.39% and 64.59% for the original and augmented datasets, respectively, in a seven-class classification task. …

Development Of A Metapgs For Accurate Prediction Of Osteoporotic Fracture, Xiangxue Xiao

UNLV Theses, Dissertations, Professional Papers, and Capstones

Introduction: Early identification of individuals at high-risk for osteoporotic fractures who may benefit from preventive intervention is essential. However, the predictive accuracy of the currently used fracture risk assessment tool remains suboptimal. The first aim of this research is to construct genome-wide polygenic scores for the femoral neck (PGS_FNBMD_idpred) and total body BMD (PGS_TBBMD_idpred) and to estimate their potential in identifying individuals with a high risk of osteoporotic fractures. The second aim is to validate the predictive performance of two previously established PGSs (PGS_FNBMD_idpred and PGS_TBBMD_idpred) in an external cohort …

Informing Management Strategy For The Relict Leopard Frog (Rana Onca): Insights Into Breeding Biology And An Attempt To Improve Augmentation Success Through Pre-Exposure And Clearance Of An Emerging Amphibian Pathogen, Rebeca Rivera

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Relict Leopard Frog, Rana onca, is a species of conservation concern that suffered a decline sometime during the 20th century. Even after two decades of intensive management, the species currently only occupies 20 spring sites in southern Nevada and northwestern Arizona. The causes for the historical decline are mostly speculative, but relate to habitat loss, introduced predators, and emergent disease. Since 2001, R. onca has been under an intensive conservationprogram managed by a multiagency conservation team. There are several objectives specified in the program including the need to investigate the biology of the species and incorporate findings into …

Development And Characterization Of Lead & Lead-Free Perovskite Solar Cell Materials, Rubaiya Murshed

UNLV Theses, Dissertations, Professional Papers, and Capstones

In recent years, perovskite photovoltaic technology has offered enormous viability and dimensionality in solar cell research. As a light-harvesting active layer, Perovskite generated remarkable development in device efficiency of 25.7% for the single-junction solar cell, and over 33% for the perovskite/silicon tandem solar cell. Also, perovskite-perovskite tandem solar cell (also called all-perovskite tandem solar cell) shows great potential in device performance and achieved a power conversion efficiency (PCE) of 26.4%. Transitioning photovoltaic technology from the laboratory to commercial products, high PCE, low cost, long lifetime, and low toxicity are some of the critical factors to consider during material selection. Pb-halide …

Benchmarking And Practical Evaluation Of Machine And Statistical Learning Methods In Credit Scoring: A Method Selection Perspective, Gwen Verbeck

UNLV Theses, Dissertations, Professional Papers, and Capstones

Predictive models are important tools used in all scientific fields. Machine learning (ML) algorithms and statistical models are widely used for decision-making because of their capability to tackle intricate and unique problems. In domains where data are high-dimensional and contain irrelevant and redundant features, ML algorithms are known to have superior performance over traditional (statistical) learning methods. However, researchers and analysts are often faced with a myriad of techniques to choose from, with no clear consensus on which will perform best for their specific task. Considering resource limitations, exhaustive exploration of all available methods is impractical and often fails to …