Digital Commons Network^™

Dft Investigation Of Lewis Acid Assisted C-Cn Bond Activation Of Benzonitrile With [Ni(Dmpe)] Fragment, Lubna Kader

Theses and Dissertations

There has been recent interest in the field of organometallics with C—C bond activation of organic substrates that are mediated by transition metal complexes. The bond activation of C—C bonds is important, not only in organic synthesis but also in industrial processes. However, the activation of these bonds remains difficult since they are thermodynamically more stable and sterically less available to activate than the activation of the C—H bond. Most of the successful C—C cleavage uses the relief of ring strain, achievement of aromaticity, or proximity, as the driving force for the reaction.3 Another strategy is the use of a …

Gmres Convergence Of Block Preconditioners For Nonsymmetric Matrices, Miguel A. Mascorro

Theses and Dissertations

GMRES is an iterative method for solving linear systems that minimizes the residual over the k-dimensional Krylov subspace at iteration k. Murphy, Golub and Wathen in [11] show that saddle point type matrices can be preconditioned so that GMRES converges in two or three steps. Ipsen in [10] extends this work to matrixes where the (2,2) block is nonzero. However, the three step convergence result no longer holds in this case. In this thesis we investigate how many more steps are needed for convergence as a function of the size of that (2,2) block.

Influence Of Pretreatments On Physiological Status And Post-Planting Survival Of Thornforest Seedlings In A Restoration Context, Douglas E. Mainhart

Theses and Dissertations

Semi-arid ecosystems across the globe have faced land conversion posing a threat to the important ecosystem services they provide. Revegetation-centered restoration efforts in arid regions have low success due to limited water availability and higher temperatures. Typically, practitioners utilize methods that modify field conditions around seedlings to mitigate these stressors. I evaluated the efficacy of in-nursery treatments to improve plant water status. Three pretreatments were applied: elevated CO2, drought hardening, and an antitranspirant foliar spray. My goal was to understand how these pretreatments would impact survival and growth in the field and what physiological traits they altered. Elevated CO2 and …

Special Education Teachers’ Self-Efficacy During The Times Of A Global Pandemic, Vanessa G. Leal

Theses and Dissertations

This quantitative dissertation aims to describe and compare the perception of special education teachers' self-efficacy amid the COVID-19 pandemic using the practice of distance and their self-efficacy pre-pandemic using face-to-face instruction and describe the perceived valuable supports teachers received from educational leaders during the pandemic and considered valuable. The study population includes special education teachers teaching in inclusive settings before and during the pandemic in grades 6–12 in districts located in South Texas. The current study's data was analyzed using a two-way factorial analysis of variance, with both factors including repeated measures within subjects (2 x 3). A descriptive statistical …

A Study Of The Constitutive Models Used In Analyzing Dynamic Strain Aging In Austenitic Stainless Steel 304, Mohammad Mohiuddin

Theses and Dissertations

When triggered, dynamic strain aging has a significant impact on the microstructural mechanical behavior of austenitic stainless steel 304 high performance alloy. The dynamic strain aging phenomenon has been shown to cause significant additional hardening in several experimental studies. To effectively predict the behavior of the material, it is required to employ a constitutive model that includes dynamic strain aging. The extra hardness brought on by dynamic strain aging is captured in this study by the proposal of a novel constitutive model (VAS model) for Austenitic Stainless Steel (ASS) 304 high performance alloy. As part of this study, the developed …

Investigating The Relationship Between Dissolved Oxygen And Nitrate Concentration As A Proxy For Marine Ecosystem Health, Natalia M. Moore

Theses and Dissertations

Coastal environments such as seagrass meadows span a wide range of spatial scales and can experience disturbances that cause rapid shifts to ecosystem dynamics. Increased pressure to the coastal zone has highlighted the need for constant, real-time monitoring to monitor current ecosystem status. A custom, low cost, high resolution, in situ sensor network was designed and tested in the Lower Laguna Madre, Texas to characterize primary productivity in seagrass meadows through gradient patterns of dissolved oxygen concentration, with the purpose of determining whether seagrass or phytoplankton were the more dominant primary producer. There was a distinct vertical and horizontal gradient …

Incorporating Native Plants In Insectary Strips To Promote Insect Diversity And Below-Ground Beneficial Microbes In South Texas, Lindsey N. Richards

Theses and Dissertations

Farm edges are generally the most undisturbed areas in a farm with diverse vegetation and can enhance agrobiodiversity and provide crucial food and shelter for wildlife, insects, and soil biota. Planting native wildflowers with the ability to reseed and withstand local climatic conditions for semi-permanent vegetation around farm edges or in between crops has potential to biologically control pests. To test this, we ran a two-year study and installed three different flowering insectary strips on a certified organic vegetable farm in South Texas during the winter season. The treatments were: 1) a commercially sourced 17-species native wildflower seed mix; 2) …

Weather Parameters Influencing The Incidence Of Citrus Canker Caused By Aw Strain In The Rio Grande Valley, Amit Sharma

Theses and Dissertations

Citrus canker caused by bacterium Xanthomonas citri subsp. citri (Xcc) seriously affects the citrus industry by making the fruit unmarketable due to unsightly lesions on the fruit. Canker caused by Aw strain of Xcc was reported in the citrus trees located in the residential areas of the Rio Grande Valley (RGV). Canker severity differs amongst cultivars/varieties, and it is influenced by prevailing environmental conditions. Multiple regression modeling of the disease incidence with the environmental variables such as temperature, humidity, windspeed, wind gust, and rainfall was performed to understand the environmental conditions that are favorable for spread of citrus …

Exploring The Path To Becoming A Female, Hispanic Stem Educator: A Phenomenological Inquiry, Cristina Saldaña

Theses and Dissertations

This qualitative study sought to understand the lived experiences of the participants to identify factors that contributed to their decision of becoming a secondary STEM educator. Participants were identified through criterion sampling, which ensured that the participants were (1) female, (2) Hispanic, and (3) and teach mathematics, science, or engineering (subjects in the STEM field) at the secondary level (e.g. grades 9-12). Through a phenomenological approach, the participants participated in two interviews. The resulting narrative data was then coded and analyzed through an iterative process. The resulting codes were then analyzed to determine any emergent themes. Four themes and five …

Water Hardness Removal By Electrochemical Precipitation In A Continuous Flow Condition Using Conductive Concrete As Cathode, Tahsin Tareque

Theses and Dissertations

This study focuses on the electrochemical precipitation (EP) process to reduce excess water hardness from the Lower Rio Grande Valley (LRGV) tap water using electrically conductive concrete as cathode in a continuous flow condition. LRGV tap water is extremely hard with hardness more than 350 mg/L as CaCO3. Humans can pleasantly consume water with hardness less than 150 mg/l as CaCO3 according to World Health Organization (WHO). Hard water is also known to cause mechanical problems to boilers and heat exchangers. In this process, electricity is passed through electrodes submerged in electrolyte, which causes an alkaline environment around the cathode …

Feasibility Analysis Of Embedding Optical Fiber Sensor Into Additively Manufactured Part, Mahmudul Hasan Porag

Theses and Dissertations

The research tried to examine the viability of the embedment of optical fiber sensors in Additively built components, packaging the sensors within the components, and characterizing the sensors for sensing a specified measurement. Optical fiber sensors are popular due to their small size, resilience against electromagnetic radiation, and reliability in potentially dangerous conditions. Embedding fibers inside a product allows for the monitoring of critical areas, allowing for preemptive action in the case of a breakdown. Coupons of Inconel 718 were made using laser powder-bed fusion (LPBF), with the fabrication settings tuned to determine whether such a development was possible. After …

Integrating Model-Based Systems Engineering Industry Transformations For Workforce Development, Wilma Analisa Ankobiah

Theses and Dissertations

This study explores whether MBSE industry workforce requirements are being satisfied by the academic curricula of US institutions. Using an industry survey, which is highlighted in Chapter 3, identifies the existing perception of MBSE from various industries and explores the MBSE needs of professionals, such as tools concepts and languages. It examines how industry professionals perceive MBSE, the advantages and challenges of MBSE use and the preferred MBSE tools, languages and knowledge of concepts deemed necessary to ensure project success in the respective industry sectors. Results of phase 1 industry survey will summarize the current MBSE concepts, tools and languages …

South Texas Wildlife Activity Across A Fragmented Landscape And Road Mitigation Corridor, Caitlin K. Brett

Theses and Dissertations

Wildlife crossing structures (WCS) and roadside fencing are commonly installed to mitigate habitat fragmentation, wildlife road mortalities, and other negative effects that roads can have on the surrounding landscape. Eight such WCS were constructed below Farm-to-Market (FM)106 in Cameron County, Texas, across a 16 km corridor transecting the Laguna Atascosa National Wildlife Refuge. These WCS, paired with adjacent roadside fencing, were intended to prevent road mortalities of the endangered ocelot (Leopardus pardalis) and to mitigate the barrier effect of FM106 on this and other meso-mammal species. This study will analyze camera trap data from roadside and habitat reference …

Recuerdos De Mi Niñez, Noel Barsenas

Theses and Dissertations

This thesis contains an original work for orchestra that features programmatic elements and musical gestures referencing previous generations of composers as well as other influential relatives of the author that are then recombined into a personal style. The document also contains commentary about the piece’s personal, historic, and cultural contexts, as well as a theoretical analysis addressing the form, structure, and harmonic content of the work.

Navigating Through A Pandemic (The Unknown): The Effects Of Synchronous Learning For Online And In Person Students On Achievement Scores In Reading And Math In A Private Catholic School In South Texas, Israel Martinez Jr.

Theses and Dissertations

In the Spring of 2020, a wide world pandemic, specifically COVID-19, slammed the door on what we defined as normal life. COVID-19 and its associated pandemic exposed more explicitly great inequities such as access to devices, platforms, and/or places to do schoolwork outside schools in education systems (Fullan, 2020). It also interrupted international travel, it devastated economic growth, and it disrupted schooling globally (Harris & Jones, 2020). In the Summer of 2020, a Catholic school in South Texas set a plan in place to provide a 100% synchronous way of learning for students in elementary grades 1 through 8 to …

Grapefruit Peel Biochar Applications For Immobilizing Copper And Lead In Soil, Michael Alfredo Navarro

Theses and Dissertations

This study investigated the efficacy of grapefruit peel (GP) derived biochar materials (two pyrolysis temperatures 450°C and 800°C) as a potential adsorbent to immobilize heavy metal (copper and lead) in a local sandy loam clay soil. A batch adsorption test with heavy metal concentrations at 50 mg L-1, and 100 mg L-1 revealed that soil itself had the highest immobilization percentage compared to the GP biochars. A soil column experiment was conducted to determine how much the GP biochar samples and the tested soil will exhibit adsorptive characteristics for heavy metals when 50 ml of 50 mg L-1 copper or …

Synthesis Of Bioactive Heterocycles, Shaila Akter Shetu

Theses and Dissertations

The Discovery of a variety of heterocyclic drugs for the treatment of cancer and other diseases (e.g, neglected tropical diseases) is a medical breakthrough and inspiring for the research community as a whole. A wide range of natural, semi-synthetic, and synthetic anticancer drugs are synthesized using various methods. Among them, β -lactams stand out as a novel class of antibiotics that has different types of biological as well as anti-cancer properties. β -lactam has become a premier and active research subject towards the development of revolutionary anti-cancer drugs. In recent years, a large amount of investigations have been done to …

Dataset For Electronic And Optical Properties Of Y2o2s And Er Dopped Y2o2s Calculated Using Density Functional Theory And Simulated X-Ray Near Edge Spectra, Nicholas Dimakis, Eric Baldemar Rodriguez Jr., Kofi Nketia Ackaah-Gyasi, Madhab Pokhrel

Physics & Astronomy Faculty Publications

The computational data presented in this paper refer to the research article “Optical properties and simulated x-ray near edge spectra for Y2O2S and Er doped Y2O2S”. We present the data used to calculate the structural, electronic, and optical properties of the Y2O2S and its Er+3 doped counterparts at various concentrations using density functional theory (DFT) and simulated X-ray near edge (XANES) spectra. We report electronic information from DFT and DFT+U generated from the Vienna Ab initio Simulation Package (VASP) using PAW pseudopotentials. We also report VASP calculated optical properties for the host Y2O2S using the independent particle approximation (IPA), the …

The Impacts Of Supporting Productive Struggle Teaching Practice On Students’ Conceptual Understanding, Procedural Fluency, And Strategic Competence: The Case Of Quadratic Functions, Sumeyra Karatas

Theses and Dissertations

This quasi-experimental design study aimed to examine how exposure to supporting productive struggle teaching practice impacts students’ conceptual understanding, procedural fluency, and strategic competence when solving high-demanding quadratic functions problem solving tasks. Results suggested that students in the supporting productive struggle teaching practice group performed significantly better than students who received facilitated instruction in every three strands of mathematical proficiency (i.e., conceptual understanding, procedural fluency, and strategic competence). By examining the effectiveness of supporting productive struggle teaching practice, this study offers insight into the conceptions and strategies teachers can implement in their classrooms to improve students’ mathematical proficiency.

Code Of Ethics Quality And Audit Fees, Hong Kim Duong, Giorgio Gotti, Michael T. Stein, Anthony Chen

School of Accountancy Faculty Publications

Using a sample of U.S. firms from 2003 to 2018, we examine the effect of an audit client’s code of ethics quality on audit fees. We find that clients with a lower code of ethics quality pay significantly higher audit fees, suggesting that auditors perceive such clients as riskier and charge greater risk premiums. We also find that such clients have higher litigation risk and auditors spend greater effort when auditing such clients. Our study is among the first to demonstrate the role of a client’s code of ethics quality in audit pricing. Overall, our findings are consistent with …

Reproducibility In Human-Robot Interaction: Furthering The Science Of Hri, Hatice Gunes, Frank Broz, Chris S. Crawford, Astrid Rosenthal-Von Der Putten, Megan K. Strait, Laurel Riek

Computer Science Faculty Publications

Purpose of Review

To discuss the current state of reproducibility of research in human-robot interaction (HRI), challenges specific to the field, and recommendations for how the community can support reproducibility.

Recent Findings

As in related fields such as artificial intelligence, robotics, and psychology, improving research reproducibility is key to the maturation of the body of scientific knowledge in the field of HRI. The ACM/IEEE International Conference on Human-Robot Interaction introduced a theme on Reproducibility of HRI to their technical program in 2020 to solicit papers presenting reproductions of prior research or artifacts supporting research reproducibility.

Summary

This review provides an …

Non-Archimedean Quantum Mechanics Via Quantum Groups, Wilson A. Zuniga-Galindo

School of Mathematical & Statistical Sciences Faculty Publications

We present a new non-Archimedean realization of the Fock representation of the q-oscillator algebras where the creation and annihilation operators act on complex-valued functions, which are defined on a non-Archimedean local field of arbitrary characteristic, for instance, the field of p-adic numbers. This new realization implies that many quantum models constructed using q-oscillator algebras are non-Archimedean models, in particular, p-adic quantum models. In this framework, we select a q-deformation of the Heisenberg uncertainty relation and construct the corresponding q-deformed Schrödinger equations. In this way we construct a p-adic quantum mechanics which is a …

Review Of Vegetable Nanolubricants For Tribological Applications, Laura Peña-Parás, Martha Rodríguez-Villalobos, Demófilo Maldonado-Cortés, José Andrés González, Ricardo De Jesús Durán, Javier A. Ortega

Mechanical Engineering Faculty Publications

About 40 million tons of lubricants are used every year for various industry purposes and applications, where most of them are petroleum based oils. These oils are difficult and expensive to dispose of, have low biodegradability and are contamination risks. Recent efforts have been focused on reducing the environmental impact of petroleum based lubricants through the use of vegetable oils since they are biodegradable and have good lubricity. A drawback of vegetable oils is their poor thermal stability and oxidation, which causes them to decrease their properties at higher loads. Nanoparticle (NP) additives have been explored for improving the tribological …

A Survey On Security Analysis Of Amazon Echo Devices, Surendra Pathak, Sheikh Ariful Islam, Honglu Jiang, Lei Xu, Emmett Tomai

Computer Science Faculty Publications

Since its launch in 2014, Amazon Echo family of devices has seen a considerable increase in adaptation in consumer homes and offices. With a market worth millions of dollars, Echo is used for diverse tasks such as accessing online information, making phone calls, purchasing items, and controlling the smart home. Echo offers user-friendly voice interaction to automate everyday tasks making it a massive success. Though many people view Amazon Echo as a helpful assistant at home or office, few know its underlying security and privacy implications. In this paper, we present the findings of our research on Amazon Echo’s security …

Optical Properties And Simulated X-Ray Near Edge Spectra For Y2o2s And Er Doped Y2o2s, Nicholas Dimakis, Eric Baldemar Rodriguez Jr., Kofi Nketia Ackaah-Gyasi, Madhab Pokhrel

Physics & Astronomy Faculty Publications

The electronic and optical properties of Y2O2S and its Er+3 doped counterparts at various concentrations are analyzed using density functional theory (DFT) and simulated x-ray near edge (XANES) spectra. Our simulations are complemented by absorption experiments, which show Y2O2S:Er+3 light emissions in the visible and near infrared. These emissions correspond to Er f–f intraband transitions. We use DFT and DFT+U to calculate the band structure of the Y2O2S and its Er+3 doped counterparts, whereas optical properties are calculated using the independent particle approximation (IPA). The host Y2O2S optical properties are also calculated using the random phase approximation (RPA) and …

Developing Awareness Around Language Practices In The Elementary Bilingual Mathematics Classroom, Gladys Krause, Melissa Adams Corral, Luz A. Maldonado Rodríguez

Teaching and Learning Faculty Publications

This study contributes to efforts to characterize teaching that is responsive to children’s mathematical ideas and linguistic repertoire. Building on translanguaging, defined in this article as a pedagogical practice that facilitates students’ expression of their understanding using their own language practices, and on the literature surrounding children’s mathematical thinking, we present an example of a one-on-one interview and of the circulating portion of a mathematics class from a second grade classroom. We use these examples to foreground instructional practices, for researchers and practitioners, that highlight a shift from a simplified view of conveying mathematics as instruction in symbology and formal …

Non-Hermitian Skin Effect In Two Dimensional Continuous Systems, Cem Yuce, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

An extensive number of the eigenstates can become exponentially localized at one boundary of nonreciprocal non-Hermitian systems. This effect is known as the non-Hermitian skin effect and has been studied mostly in tight-binding lattices. To extend the skin effect to continues systems beyond 1D, we introduce a quadratic imaginary vector potential in the continuous two dimensional Schr¨odinger equation. We find that inseparable eigenfunctions for separable nonreciprocal Hamiltonians appear under infinite boundary conditions. Introducing boundaries destroy them and hence they can only be used as quasistationary states in practice. We show that all eigenstates can be clustered at the point where …

Fractional Sobolev Embedding With Radial Potential, Yu Su, Zhaosheng Feng

School of Mathematical & Statistical Sciences Faculty Publications

We present some embedding results of fractional Ds,2(RN) space with radial potential. To overcome the difficulty of non-compactness, we obtain the Lions-type theorems by means of the refined Sobolev inequality with the Morrey norm. Then we apply the obtained results to study the existence of ground state solution for fractional equations with radial potential.

Qualitative Analysis For A Two-Component Peakon System With Cubic Nonlinearity, Shaojie Yang, Zhijun Qiao

School of Mathematical & Statistical Sciences Faculty Publications

This paper is devoted to studying a two-component peakon system with cubic nonlinearity, which is a two-component extension of the cubic Camassa–Holm equation. We first discuss the local well-posedness for the Cauchy problem of the system. Then, in light of a fine structure of the system, we present the precise blow-up scenario for strong solutions to the system and derive a new blow-up result with respect to initial data. Finally, peakon solutions are discussed as well.

Bi-Dbar-Approach For A Coupled Shifted Nonlocal Dispersionless System, Junyi Zhu, Kaiwen Shao, Zhijun Qiao

School of Mathematical & Statistical Sciences Faculty Publications

We propose a Bi-Dbar approach and apply it to the extended coupled shifted nonlocal dispersionless system. We introduce the nonlocal reduction to solve the coupled shifted nonlocal dispersionless system. Since no enough constraint conditions can be found to curb the norming contants in the Dbar data, the “solutions” obtained by the Dbar dressing method, in general, do not admit the coupled shifted nonlocal dispersionless system. In the Bi-Dbar approach to the extended coupled shifted nonlocal dispersionless system, the norming constants are free. The constraint conditions on the norming constants are determined by the general nonlocal reduction, and the solutions of …