Physical Sciences and Mathematics Commons^™

Study Of Multielectron Redox Chemistry In Bimetallic Complexes And Metal-Free Macrocycles, Nancy Rodriguez Lopez

Open Access Theses & Dissertations

Multielectron redox chemistry is fundamental for the activation of small molecules (e.g. H2O, CO2, CO, N2). Although these processes are of great importance, they are not well understood. Unravelling the mechanisms of electron transfer and its principles is essential for the design and development of efficient catalysts. Our approach towards the understanding of multielectron redox chemistry includes theoretical study of mechanistic pathways in the hydrogen evolution reaction (HER) by metal-free porphyrinoids, the study of electronic communication in non-symmetric multimetallic two-state models (D–B–A) and the tuning of the electronic properties of bimetallic systems (Mo, and Au) by ligand control.

In Chapter …

Dust Storms And The Dispersal Of Aquatic Invertebrates In The Chihuahuan Desert Ecoregion, Jose Rivas Jr.

Open Access Theses & Dissertations

The Chihuahuan Desert surrounding El Paso, Texas is one of the most intense sources of dust in the Western Hemisphere. Within this vast desert are ephemeral wetlands with micrometazoan propagules contained within their sediment egg banks. Dispersal of aquatic microinvertebrates between habitats is vital for the success of their populations. Passive dispersal of the propagules provides an escape mechanism from unfavorable conditions. Upon desiccation of these habitats, windstorms can potentially transport propagules mixed within entrained sediments across regional scales. To study this process, I collected falling sediment from 91 windstorms, with 59 samples collected at the University of Texas at …

Near Room Temperature Magnetocaloric Materials For Magnetic Refrigeration, Eduardo Martinez Teran

Open Access Theses & Dissertations

Magnetic refrigeration (MR) is a cooling process based on the magnetocaloric effect (MCE) that is present to some extent in all magnetic materials, and the ones in which this effect is more appreciable are called magnetocaloric materials (MCM). The implementation of new designs and materials for the construction of cooling systems is a must do, being essential that these improved designs will reduce the environmental impact and increase the efficiency of their predecessors. In this thesis, the magnetocaloric effect theory is presented from a thermodynamic point of view and also the synthesis and study to a new Heusler alloy (MnFe2Ga) …

Dimensionality Of Magnetism In Trirutile Cota2o6 And Its Derivatives, Raju Baral

Open Access Theses & Dissertations

In this thesis, we addressed the question of low dimensionality of trirutile compound CoTa2O6 and studied how the low dimensionality evolved with doping of Mg on Co-site. In order to study low dimensionality in CoTa2O6 and its derivative compounds Co1-xMgxTa2O6 (x = 0.1, 0.3, 0.5, 0.7, and 1), we used different techniques: X-ray diffraction, magnetic susceptibility, magnetization, specific heat and elastic neutron diffraction. We have addressed the question of low dimensional magnetism of CoTa2O6 by preparing phase-pure samples of the compound. In CoTa2O6 a broad feature is observed in magnetic susceptibility at 10 K and an antiferromagnetic phase transition is …

Energy Efficiency And Fatigue Failure On Gears And Bearings For Processing Rebar Steel, Jesus Gabriel Garcia

Open Access Theses & Dissertations

Steel industry is a major emitter of air pollutants, a leading industrial consumer of water, a minor source of contaminated liquids, a massive producer of solid waste, and a significant source of CO2. The objective on this thesis work is to minimize the greenhouse gas emissions when processing steel. Gears and bearings were evaluated based on their performance when exposed to cyclic stresses. The importance for having a proper set up on rolling mills to increase efficiency for processing rebar steel has been detailed on paper. In contrast, mechanical vibration has been measured on gears and bearings to determine efficiency …

Inverse Gaussian Ornstein-Uhlenbeck Applied To Modeling High Frequency Data, Emmanuel Kofi Kusi

Open Access Theses & Dissertations

With about 226050 estimated deaths worldwide in 2010, an earthquake is considered as one of the disasters that records a great number of deaths. This thesis develops a model for the estimation of magnitude of future seismic events.

We propose a stochastic differential equation arising on the Ornstein-Uhlenbeck processes driven by IG(a,b) process. IG(a,b) Ornstein-Uhlenbeck processes offers analytic flexibility and provides a class of continuous time processes capable of exhibiting long memory

behavior. The stochastic differential equation is applied to geophysics and financial stock markets by fitting the superposed IG(a,b) Ornstein-Uhlenbeck model to earthquake and financial time series.

Ibuprofen As A Probe Of Lipid Metabolism, Jose Antonio Rosales

Open Access Theses & Dissertations

The hypothesis that deracemization of racemic ibuprofen (IBU) occurs via the enolization of a Candida rugosa lipase (CRL)-ibuprofen ester (Scheme 1.6.2) was disproven by reacting racemic IBU under the conditions that were used to deracemize ibuprofen methyl ester (IME), namely pH 7.6. At pH 7.6, IME through IBU butyl esters were not formed in-situ and racemic IBU was not deracemized by reacting the corresponding primary alcohol with racemic IBU in the presence of CRL.

At pH 7.6, hexyl through dodecyl IBU esters were formed in-situ by reacting the corresponding primary alcohol with racemic IBU in the presence of CRL. The …

Electron Binding Energy Of Polar Molecules Using Fermi Löwdin Orbital Self Interaction Corrected Density Functional Scheme, Peter Obinna Ufondu

Open Access Theses & Dissertations

Density functional theory (DFT) has become a standard method for electronic structure calculations in physics. The standard approximate density functional usually do not bind this class of anions, due to self-interaction error (SIE). We apply the recently developed Fermi Löwdin orbitals based self-interaction correction method (FLOSIC) with long-range diffuse Gaussian functions to study dipole bound anions and negatively charged water clusters. These calculations are carried out using Perdew-Wang (1992) local spin density PW91-LDA, Perdew-Burke-Ernzerhof PBE-GGA, and the recently developed Strongly Constrained and Appropriately Normed SCAN-meta-GGA functional which satisfies all the known constraints for exchange-correlation functional. Plot from FLOSIC density difference …

Mineral Exploration Investigation In The Northern Sierra Madre Occidental, Mexico, Labdan Nijr Alqahtani

Open Access Theses & Dissertations

The Sierra Madre region is rich in mineralized deposits, but it is hard to access because of the rugged terrain. Remote sensing and GIS can help in mineral exploration and regional structural analysis. The purpose of this project is to study linear, curvilinear, arcuate, and circular features in the Sierra Madre Occidental of Mexico in order to improve exploration possibility. It is of great interest to know the relationship between lineament intersections, caldera features because of the location of potential mineral occurrences. In this study, 4,445 lineaments were mapped manually using directional filters applied to satellite images. A total of …

Sequence Stratigraphy, Diagenesis, And Depositional Facies Of An Exposed Megaflap: Pennsylvanian Hermosa Group, Gypsum Valley Salt Wall, Paradox Basin, Colorado, Kyle Thomas Deatrick

Open Access Theses & Dissertations

Outcrop exposures mostly of the Pennsylvanian Honaker Trail Formation provide a 2 km strike-oriented view of a megaflap on the southwestern flank of the Gypsum Valley salt wall, Paradox Basin, Colorado that serves as an outcrop analog for megaflaps recently drilled unexpectedly in the Gulf of Mexico and other salt basins worldwide. The near vertical (80-90°) stratal panel comprises a 60 m thick succession of non-evaporite facies of the Pennsylvanian upper Paradox Formation, overlain by a 117 m section of cyclic shallow marine carbonates and siliciclastics of the Honaker Trail Formation. Near vertical upper Paradox and Honaker Trail strata are …

Structural And Sedimentological Analysis Of The Bear Canyon Conglomerate, Southeastern California: Implications For The Timing And Style Of Miocene Deformation Within The Eastern California Shear Zone, Garrett Goff

Open Access Theses & Dissertations

The region between Indian Pass and Picacho State Recreation Area (PSRA) in southeastern California records complex deformation related to the transition from a Paleogene convergent margin to a Neogene transform setting, although the timing and nature of youngest deformation in this region remains incompletely known. A 1.7 km-thick section of Miocene Bear Canyon conglomerate (BCC) was studied to constrain this young period of deformation. These rocks lie unconformably upon 23 Ma volcanic and epiclastic rocks and a Mesozoic metamorphic basement terrane. Near PSRA the BCC contains locally derived clasts and can be further subdivided into three unconformity-bounded sequences, referred to …

Petrophysical, Geostatistical And Geo-Spatial Analysis Of Round Top Mountain Rhyolite (Hudspeth County, West Texas, Usa), Lorraine Marie Negron

Open Access Theses & Dissertations

This project consists of three separate projects that all investigate Round Top Mountain, a rhyolite laccolith located in Sierra Blanca, west Texas in Hudspeth County (U.S.A). The three projects will explore and analyze the petrophysical, geostatistical and geo-spatial aspects of this unique deposit.

Project 1:

This petrophysical study examines the porosity and micro-permeability of the Round Top rhyolite at a scale, roughly 5 to 10 mm or pebble sized, similar to anticipated heap leach crush sizes. Large voids and fluid paths, such as faults and joints in the massive rock (meter to km scale, boulder to outcrop size), are not …

Magnetic Nanoparticles For Hyperthermia For Cancer Treatment, Bianca Paola Meneses Brassea

Open Access Theses & Dissertations

Fe3O4 and NixCu4-x magnetic nanoparticles were synthesized using supercritical conditions of liquids and wet chemistry, respectively. Characterization methods (VSM, SEM, TEM, and magnetic hyperthermia) yielded results that prove feasibility for magnetic hyperthermia for cancer treatment.

New Porous Semiconductor Nanocomposites As Dye-Sensitized Photocatalysts, Tahmina Akter

Open Access Theses & Dissertations

The wide band gap layered semiconductors potassium titanium niobium oxide (KTiNbO5) and potassium hexaniobate (K4Nb6O17) along with a metal co-catalyst can be been used to generate hydrogen fuel from water. However, ultraviolet light is required, which limits their utility in solar energy conversion. Modification of these types of semiconductors can sensitize them to visible light, providing a promising way to produce clean, renewable hydrogen (H2) fuel. Many photocatalysts suffer from poor H2 production efficiencies under visible light, due to inadequate and unstable sensitizers, resulting in photocatalysts that fail quickly.

In this research, several new high surface area dye sensitized nanocomposites …

Mesacs: A Multi-Method Environmental Study Over The Arctic Chukchi Sea, Julio Eduardo Ceniceros

Open Access Theses & Dissertations

The Arctic environment is a dynamic part of Earth’s natural system and is currently undergoing rapid increasing air temperature and decreasing sea ice extent, leading to more open ocean waters. As open water areas become more prevalent, phytoplankton communities near the surface of the ocean can proliferate earlier in the year and are apt to reach higher concentrations by the end of the summer season. Phytoplankton biomass around the world has been known to produce a microscopic biofilm at the surface of the ocean composed of biogenic and biological particles which then become airborne and work as both cloud condensation …

Application Of Urinary Metabolites For Cancer Detection, Qin Gao

Open Access Theses & Dissertations

Prostate cancer (PCa) is the 3rd most common cause of male cancer mortality in the US. Early diagnosis and treatment of PCa will improve the quality of care and reduce mortality. The prostate specific antigen (PSA) is commonly used in the current PCa screening, but its limitation has resulted in an intense search for more reliable biomarkers. Studies showed that dogs could differentiate PCa patients from negative control by sniffing their urine. As the odor profiles are generated by volatile organic compounds (VOCs), the finding suggests that particular VOCs could be linked to PCa, PCa risk levels and other cancers. …

Stratigraphic And Structural Characterization And Evolution Of Exposed Megaflaps Flanking Salt Diapirs, Cora Evelyn Gannaway Dalton

Open Access Theses & Dissertations

A Neoproterozoic salt system exposed in the Willouran Ranges of South Australia and a Mesozoic salt system in the south-central Pyrenees of Spain provide natural laboratories to investigate the stratigraphic and structural development of megaflaps flanking salt diapirs. Megaflaps are near-vertical to overturned, deep minibasin stratal panels that extend far up the flanks of steep diapirs or their equivalent welds. Megaflaps can form by halokinetic drape-folding, contraction, or a combination of these processes. The existing models of megaflap development are based primarily on seismic data, well penetrations, cross-section restorations, and numerical and analog modeling. Investigation of the sedimentology, stratigraphy, and …

Computational Studies On Perovskite-Metallofullerene Interface And Magnetic Properties Of Mn-Based Mixed Olivines, Bethuel Omutiti Khamala

Open Access Theses & Dissertations

Methyl ammonium lead halide (MAPbX3) perovskite based solar cells have recently emerged as promising class of materials for photovoltaic applications with efficiencies reaching over 22%. Designing interfaces with strong binding is vital to developing efficient, high-performing solar cells. Fullerene-based materials are widely employed as efficient electron acceptors and can serve as electron transporting layer in perovskite based solar cells. We have studied interfaces of methyl ammonium lead iodide MAPbI3 with Sc3N@C80 fullerene and Sc3N@C80PCBM fullerene derivate within the density functional formalism. Different surface terminations and orientations of the methyl ammonium are examined for binding of the fullerene layer. Our calculated …

Synthesis Of Advanced Functional Nanomaterials For Sustainable Water Treatment Technologies, Md Tariqul Islam

Open Access Theses & Dissertations

Water is the most essential resource for the sustenance of life. Water is also necessary for agriculture, industry, household, and environmental conservation. However, due to large population growth and industrial expansion, access to clean water is becoming increasingly difficult around the world. Current water treatment technologies have not changed in over one hundred years and require a large infrastructure due to their low efficiencies and large-scale needs. In this context, the utilization of advanced functional nanomaterials and the adaptation of nanotechnology could potentially allow for miniaturizing water treatment and develop de-centralized solutions for rural areas. This Dissertation presents the design, …

A Bottom-Up Modeling Methodology Using Knowledge Graphs For Composite Metric Development Applied To Traffic Crashes In The State Of Texas, Daniel Michael Mejia

Open Access Theses & Dissertations

Data is a key factor for understanding real-world phenomena. Data can be discovered and integrated from multiple sources and has the potential to be interpreted in a multitude of ways. Traffic crashes, for example, are common events that occur in cities and provide a significant amount of data that has potential to be analyzed and disseminated in a way that can improve mobility of people, and ultimately improve the quality of life. Improving the quality of life of city residents through the use of data and technology is at the core of Smart Cities solutions. Measuring the improvement that Smart …

Seismic Analysis Of The 30 July 1972 Sitka Earthquake Aftershocks, Stress Drop Of Aftershocks In Cook Strait, New Zealand Following The 2013 Cook Strait And Lake Grassmere And 2016 Kaikoura Earthquakes, And 2d Seismic Tomography In The Brady Hot Springs Geothermal Site, Nevada, Juan Alejandro Ochoa Chavez

Open Access Theses & Dissertations

The 1972 Mw 7.6 Sitka earthquake is the largest earthquake to have occurred along the Alaska portion of the Queen Charlotte fault (QCF) in historic time. The QCF system forms the plate boundary between the Pacific and North American plates within southeastern Alaska and has accumulated enough slip since 1972 to produce a comparable sized event in the near future. Thus, it is important to better understand the controls on the rupture process of the 1972 mainshock and its aftershocks. Following the mainshock the U.S. Geological Survey installed a network of 11 portable seismographs that recorded over 200 aftershocks of …

Zircon (U-Th)/He Thermochronologic Investigation Of The Long-Term Thermal History Of Proterozoic Rocks In West Texas And Southern New Mexico, Nathan Zachary Reade

Open Access Theses & Dissertations

The tectonic history of west Texas and southern New Mexico is well documented, however existing geologic data only provide limited snapshots of the region’s prolonged and complex tectonic evolution. Zircon (U-Th)/He (ZHe) thermochronology is used to examine the long-term thermal history of Proterozoic rocks exposed in the southern Rio Grande rift. ZHe data were collected from the Carrizo Mountains (10 dates), Cookes Range (16 dates), and Franklin Mountains (30 dates) in order to constrain the long-term (>1 Ga) thermal history of rocks in this region and relate this history to known tectonic or climatic events. Individual ZHe dates range …

Investigation Into The Effects Of Copper Based Nanoparticles On Sugarcane (Saccharum Officinarium) And Zucchini (Cucurbita Pepo), Carlos Tamez

Open Access Theses & Dissertations

The widespread use of copper-based nanomaterials has been accompanied by an increasing interest to understand their potential risks. Due to high surface area to volume properties, nanomaterials are more reactive than their bulk counterparts. Copper nanoparticles are used in numerous products, and could enter the environment through their synThesis or incidental use. It is essential to understand the effects of nanoparticles on edible crops by performing both short-term and long-term experiments at relevant exposure concentrations. In order to evaluate biochemical and physiological effects crops, sugarcane and zucchini, were grown in soil amended with: Kocide 3000 (copper-based fungicide), nano-sized CuO (nCuO), …

A Study Of Solvent Effects On The Ground And Excited States Of Endohedral Tri-Scandium Nitride C80 Fullerene Coupled With Zinc Phthalocyanine And Metal-Free Phthalocyanine Using Dft-Pcm Method, Timilsina Prasad Timlsina

Open Access Theses & Dissertations

The photovoltaic active materials composed of endohedral metafullerene and phthalocyanine derivatives are known as excellent electron donor-acceptor pairs. The tri-metallic nitride endohedral C80 fullerene exhibits high absorption coefficients in the visible region of the spectrum and has similar electron-accepting abilities as that of C60 fullerene, which can allow for higher efficiencies in OPV devices. In this study, we examine the effect of solvent on the charge transfer excitation energies of Sc3N@C80-ZnPc and Sc3N@C80-H2Pc donor-acceptor molecular complexes. Three different solvents with different polarity - water, toluene, and acetone are used. The solvent is modeled as a polarizable continuum as implemented in …

Spectroscopic Analysis Of Calcium Oxalate Kidney Stone Inhibition By Nordihydroguaiaretic Acid (Ndga), Mahendra Subedi

Open Access Theses & Dissertations

This current study provides information regarding the inhibition of calcium oxalate type of kidney stones by the use of nordihydroguaiaretic acid (NDGA). Around 80% of kidney stones found in patients are principally made of calcium oxalate and calcium phosphate. NDGA is an antioxidant compound that is chemically extracted from the desert bush Larrea tridentata. This work is a logical continuation of a previous research, where different concentrations of Larrea tridentata extract were used for such inhibition. Size and morphological changes from a calcium oxalate monohydrate (COM) structure to a calcium oxalate dihydrate (COD) structure were previously reported.

In the current …

Potential Of Nanoscale Elements To Control Fusarium Wilt Disease In Tomato (Solanum Lycopersicum), Enhance Macronutrient Use Efficiency, And Increase Its Yield, Ishaq Olarewaju Adisa

Open Access Theses & Dissertations

Nanotechnology has a great potential in ensuring food production, security and safety globally. Over the past decade, research on the use of nanomaterials to supply nutrient elements and protect plants from pest and diseases has significantly increased. Tomato (Solanum lycopersicum) is one of the most consumed vegetables in the world and United State is one of its largest producers globally generating billions of dollars annually in revenue.. Tomato plants are affected worldwide by Fusarium wilt caused by Fusarium oxysporum f. sp. Lycopersici. There is growing concern about excessive use of conventional pesticides in controlling Fusarium and other diseases in tomato …

Cantor Sets, Cantorvals, And Their Topological Structure, Ángel Adrián Agüero

Open Access Theses & Dissertations

With interesting topological properties, the Cantor set is worth studying for itself. In other areas, topological structures arise that are in fact homeomorphic to the Cantor set. In particular, we see sets that are homeomorphic to the Cantor set which result from the subsums of particular series, as well as linear combinations of algebraic sums of Cantor sets. These also result in what has been termed a Cantorval, which we also investigate.

Computer-Aided Classification Of Impulse Oscillometric Measures Of Respiratory Small Airways Function In Children, Nancy Selene Avila

Open Access Theses & Dissertations

Computer-aided classification of respiratory small airways dysfunction is not an easy task. There is a need to develop more robust classifiers, specifically for children as the classification studies performed to date have the following limitations: 1) they include features derived from tests that are not suitable for children and 2) they cannot distinguish between mild and severe small airway dysfunction.

This Dissertation describes the classification algorithms with high discriminative capacity to distinguish different levels of respiratory small airways function in children (Asthma, Small Airways Impairment, Possible Small Airways Impairment, and Normal lung function). This ability came from innovative feature selection, …

Exploring Dynamic Triggering Of Earthquakes Within The United States & Quaternary Faulting And Urban Seismic Hazards In The El Paso Metropolitan Area, Richard Alexander Alfaro-Diaz

Open Access Theses & Dissertations

Technological advances in combination with the onslaught of data availability allow for large seismic data streams to automatically and systematically be recorded, processed, and stored. Here, we develop an automated approach to identify small, local earthquakes within these large continuous seismic data records. Our aim is to automate the process of detecting small seismic events triggered by a distant large earthquake, recorded at a single station. Specifically, we apply time-domain short-term average (STA) to long-term average (LTA) ratio algorithms to three-component data to create a catalog of detections. We remove some of the false detections by requiring the detection be …

Creating Spaces For Conversations On Conservation: A Case Study Of Joint Forest Management In East Sikkim, India., Paulami Banerjee

Open Access Theses & Dissertations

Successful community-based natural resource management should include both resource professionals and local communities. Recognizing this fact, my research seeks to encourage more locally adaptive and collaborative forest governance that facilitates sustainable development by enabling grassroots participation. Specifically, I explore opportunities for developing a more sustainable relationship between India's Joint Forest Management (JFM) program and rural forest-dependent communities in Sikkim-a remote, northeastern state of India bordering Nepal to the west, the Tibet Autonomous region of China to the north and northeast, and Bhutan to the southeast. As an instrument for sustainable forestry management, JFM seeks to develop partnerships between forest user …