Digital Commons Network^™

Oxidation Of Dibenzothiophene To Dibenzothiophene Sulfone Using Tungsten (Vi) Oxide, Alejandrina Rivera

Theses and Dissertations - UTB/UTPA

The oxidation of dibenzothiophene (DBT) to dibenzothiophene-sulfone has been considered as an alternate method to remove sulfur from crude oil. This study demonstrates that the oxidative desulfurization (ODS) of DBT to DBT-sulfone occurs using WO3 as a catalyst. WO3 was synthesized and characterized using X-ray diffraction to determine the phase of WO3. Each reaction was refluxed and run for four hours using WO3 as a catalyst, dibenzothiphene, and four different solvents: decahydronapthalene, n-dodecane, decalin, and dodecane. The reactions were performed at temperatures ranging from 120 oC to 150 oC. Aliquots were taken at 30 minutes for up to four hours …

Mass Production Of Β-Silicon Carbide Nanofibers By The Novel Method Of Forcespinning, Alfonso Salinas

Theses and Dissertations - UTB/UTPA

Non-oxide Ceramics such as silicon carbide have very unique properties, for example high toughness, thermal stability, wear resistant, and thermal shock resistance these properties make these ceramic fibers excellent for high temperature applications. Here we present the development of Silicon Carbide nanofibers utilizing a Polystyrene/Polycarbomethylsilane solution as the precursor materials. The Forcespinning ® was performed under a controlled nitrogen environment to prevent fiber oxidation. Characterization was conducted using scanning electron microscopy, x-ray diffraction, and thermogravimetric analysis. The results show successful formation of high yield, long continuous bead-free nanofibers with diameters ranging from 280nm to 2 micron depending on the selected …

A Survey Of Heavy Metals In Water, Soil And The Surrounding Plants In The Lower Rio Grande Valley, Erving W. Morelius

Theses and Dissertations - UTB/UTPA

Heavy metal pollution of the environment in recent years has become a major issue of importance for both human and environmental health. Samples were investigated for the potential pollution of the area as it is a vital produce producing area. During the study plant, soil and water samples were collected from the Donna Reservoir and Canal System to test the concentration of various heavy metals. The heavy metals tested included both potentially toxic and micronutrients in the samples which included arsenic, cadmium, chromium, copper, iron, lead, nickel and sulfur. During the study, a sixty day sampling period was used to …

The Effectiveness Of Alternative Certification Teachers Versus Traditionally Trained Teachers In Three School Districts In Texas On Hispanic Students' Scores In 9th Grade Algebra I: What Leaders Should Know, Anysia R. Trevino

Theses and Dissertations - UTB/UTPA

The purpose of this quantitative study is to measure the effectiveness of alternative certification teachers versus traditionally trained teachers of 9th grade Hispanic students enrolled in Algebra I. The dependent variable, teacher effectiveness, will be measured by the students' raw score on the Texas Algebra I End Of Course (EOC) Assessment. The factors examined in this study will be 1) teachers trained through a traditional teacher certification program and 2) teachers trained through an alternative certification program. The researcher will examine the identified group of teachers' attendance as well as years of experience to determine if there is a correlation …

The Relational Algebra Toolkit: A User-Friendly Approach To Presenting And Processing Relational Algebra Queries On The Web, Jeremy J. Miller

Theses and Dissertations - UTB/UTPA

Relational algebra is the mathematical basis of tools to express and optimize queries on relational data. However, there exists no convenient way to directly use, express, store, render, visualize, and execute relational algebra over the Web. Educators and practitioners are limited to creating relational algebra expressions using TeX or equation editors which cannot execute them. This work presents a solution to this issue: the Relational Algebra Toolkit (RAT). Relational data and queries are represented using purpose-built XML vocabularies, to be both machine-processable and serializable. Encoded relational algebra expressions can be rendered as parenthetical expressions and as syntax trees, translated to …

An Integrated Multidisciplinary Nanoscience Concentration Certificate Program For Stem Education, Karen S. Martirosyan, Mikhail M. Bouniaev, Malik Rakhmanov, Ahmed Touhami, Nazmul Islam, Davood Askari, Tarek Trad, Dmitri Litvinov, Sergey E. Lyshevski

Physics & Astronomy Faculty Publications

Integration of nanoscience and nanotechnology curricula into the College of Science, Mathematics, and Technology (CSMT) at the University of Texas at Brownsville (UTB) is reported. The rationale for the established multidisciplinary Nanoscience Concentration Certificate Program (NCCP) is to: (i) develop nanotechnology-relevant courses within a comprehensive Science, Engineering and Technology curriculum, and, to offer students an opportunity to graduate with a certificate in nanoscience and nanotechnology; (ii) to contribute to students' success in achieving student outcomes across all college's majors, and, improve the breath, depth and quality of science, technology, engineering and mathematics (STEM) graduates' education; (iii) through NCCP, recruit certificate- …

Electrospinning Polymer Blends For Biomimetic Scaffolds For Acl Tissue Engineering, Vanessa Lizeth Garcia

Theses and Dissertations - UTB/UTPA

The anterior cruciate ligament (ACL) rupture is one of the most common knee injuries. Current ACL reconstructive strategies consist of using an autograft or an allograft to replace the ligament. However, limitations have led researchers to investigate tissue engineered grafts, known as scaffolds, through electrospinning. Scaffolds made of natural and synthetic polymer blends have the potential to promote cell adhesion while having strong mechanical properties. However, enzymes found in the knee are known to degrade tissues and affect the healing of intra-articular injuries. Results suggest that the natural polymers used in this study modify the thermal properties and tensile strength …

Reduction Of Nitroaromatic Compounds With Sodium Borohydride Using Transition Metal Sulfides, Samuel Pina Jr.

Theses and Dissertations - UTB/UTPA

The following systems: NaBH4/Fe3S4, NaBH4/Co3S4, NaBH4/NiS, NaBH4/CuS, and NaBH4/ZnS, were investigated for their nitro reducing abilities. Quantitative conversions were observed for the reduction of nitrobenzene with NaBH4/Co3S4 and NaBH4/NiS systems as opposed to only 9% conversion without any catalyst, representing a ten-fold increase in the reducing ability of NaBH4. In ethanol, various nitroaromatic compounds were also successfully reduced in moderate to high yields with 3 molar equivalents of NaBH4, demonstrating a mild alternative for the effective reduction of nitroaromatic compounds to their corresponding aryl amines. Screening of catalysts was carried out using gas chromatography. All products were characterized using 1 …

Graduation As A Function Of Attendance And Discipline Of Students In The Student Success Initiative Of Texas In One South Texas Urban School District, Maria Luisa Trevino-Guerra

Theses and Dissertations - UTB/UTPA

This study examined the trends and patterns across time of grade placement committee students on the dependent variable, graduation. Longitudinal data for independent variables, attendance and discipline was collected for 173 students from 2005 to 2013. The independent variables of attendance and discipline were examined to determine whether or not high school completion is dependent on these two measures.

The Grade 5 students of 2005-2006 in one south Texas large urban school district who were retained in the fifth grade or advanced to the next higher grade by the grade placement committee in accordance with the Student Success Initiative (SSI) …

Oxidation Of Dibenzothiophene To Dibenzothiophene Sulfone Using Tio2, Juan H. Leal

Theses and Dissertations - UTB/UTPA

The oxidation of dibenzothiophene (DBT) to dibenzothiophene-sulfone has been considered as an alternate method to remove sulfur from crude oil. This study demonstrates that the oxidative desulfurization (ODS) of DBT to DBT-sulfone occurs using rutile TiO2 as a catalyst with the aid of O2. In addition, anatase and brookite were synthesized and tested in the reaction. Particle size of the catalysts was calculated and morphology was explored using SEM. A kinetic study was performed to determine the catalytic effect and activation energy of TiO2. The oxidation reaction was carried out by refluxing TiO2 and DBT in decahydronapthalene while flowing O2 …

The Collegian (2013-11-18), Cleiri Quezada

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 66, No. 13

Directed Search For Continuous Gravitational Waves From The Galactic Center, J. Aasi, Daniel Bessis, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano, Robert Stone, Lappoon R. Tang, Cristina V. Torres

Physics & Astronomy Faculty Publications

We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic center region, performed on two years of data from LIGO’s fifth science run from two LIGO detectors. The search uses a semicoherent approach, analyzing coherently 630 segments, each spanning 11.5 hours, and then incoherently combining the results of the single segments. It covers gravitational wave frequencies in a range from 78 to 496 Hz and a frequency-dependent range of first-order spindown values down to −7.86×10−8  Hz/s at the highest frequency. No gravitational waves were detected. The 90% confidence upper limits …

The Pan American (2013-11-14), Norma Gonzalez, Lea Victoria Juarez

UTPA Archives - The Pan American Newspaper

Vol. 70, No. 12

Two Homologous Ef-G Proteins From Pseudomonas Aeruginosa Exhibit Distinct Functions, Stephanie O. Palmer, Edna Y. Rangel, Yanmei Hu, Alexis T. Tran, James M. Bullard

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Genes encoding two proteins corresponding to elongation factor G (EF-G) were cloned from Pseudomonas aeruginosa. The proteins encoded by these genes are both members of the EFG I subfamily. The gene encoding one of the forms of EF-G is located in the str operon and the resulting protein is referred to as EF-G1A while the gene encoding the other form of EF-G is located in another part of the genome and the resulting protein is referred to as EF-G1B. These proteins were expressed and purified to 98% homogeneity. Sequence analysis indicated the two proteins are 90/84% similar/identical. In other …

The Collegian (2013-11-04), Cleiri Quezada

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 66, No. 11

The Stochastic Background: Scaling Laws And Time To Detection For Pulsar Timing Arrays, X. Siemens, Justin A. Ellis, Fredrick A. Jenet, Joseph D. Romano

Physics & Astronomy Faculty Publications

We derive scaling laws for the signal-to-noise ratio of the optimal cross-correlation statistic, and show that the large power-law increase of the signal-to-noise ratio as a function of the observation time T that is usually assumed holds only at early times. After enough time has elapsed, pulsar timing arrays enter a new regime where the signal to noise only scales as . In addition, in this regime the quality of the pulsar timing data and the cadence become relatively unimportant. This occurs because the lowest frequencies of the pulsar timing residuals become gravitational-wave dominated. Pulsar timing arrays enter this regime …

Searching For Millisecond Pulsars: Surveys, Techniques And Prospects, Kevin Stovall, Duncan R. Lorimer, R. S. Lynch

Physics & Astronomy Faculty Publications

Searches for millisecond pulsars (which we here loosely define as those with periods < 20 ms) in the galactic field have undergone a renaissance in the past five years. New or recently refurbished radio telescopes utilizing cooled receivers and state-of-the art digital data acquisition systems are carrying out surveys of the entire sky at a variety of radio frequencies. Targeted searches for millisecond pulsars in point sources identified by the Fermi Gamma-ray Space Telescope have proved phenomenally successful, with over 50 discoveries in the past five years. The current sample of millisecond pulsars now numbers almost 200 and, for the first time in 25 years, now outnumbers their counterparts in galactic globular clusters. While many of these searches are motivated to find pulsars which form part of pulsar timing arrays, a wide variety of interesting systems are now being found. Following a brief overview of the millisecond pulsar phenomenon, we describe these searches and present some of …

A Comparison Of Site Fidelity And Habitat Use Of Red Snapper (Lutjanus Campechanus) To Evaluate The Performance Of Two Artificial Reefs In South Texas Utilizing Acoustic Telemetry, Andres Garcia

Theses and Dissertations - UTB/UTPA

Evaluation of artificial reefs is becoming an increasingly important component of fisheries management. This is particularly true for the northwestern Gulf of Mexico where natural hard substrate is limited and 359 petroleum platforms are scheduled for removal in 2013 due to the “idle iron” policy. This study compared the performance of two artificial reef configurations off the south Texas coast, the Texas Clipper and South Padre Island Near Shore Reefs that differ in material, depth, and distance from shore, with respect to behavior of red snapper, Lutjanus campechanus, an important recreational and commercial species. Red snapper were implanted with depth …

The Effects Of A Red Tide, Karenia Brevis Episode On The Benthic Macroinvertebrate Communities Of South Padre Island, Texas, Liana Lerma

Theses and Dissertations - UTB/UTPA

South Padre Island, Texas has experienced increasing frequency of harmful algal blooms (Karenia brevis) since the 1900’s, many of which resulted in massive fishes kills. In addition, shorebirds and other terrestrial wildlife deaths have been linked to K. brevis blooms prompting investigations of potential pathways by which brevetoxins may be transmitted to higher trophic levels. The benthic macrofanual community inhabiting the swash zone of sandy beaches consists primarily of filter feeding invertebrates which may serve as toxin bioaccumulators to secondary consumers of both marine and terrestrial food webs. The first reported mass mortality of swash zone benthic macrofauna on the …

Nitroxide-Functionalized Graphene Oxide From Graphite Oxide, Yazmin I. Avila-Vega, Cesar C. Leyva-Porras, Marcela Mireles, Manuel Quevedo-Lopez, Javier Macossay-Torres, Jose Bonilla-Cruz

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

A facile method for preparing functionalized graphene oxide single layers with nitroxide groups is reported herein. Highly oxidized graphite oxide (GO=90.6%) was obtained, slightly modifying an improved Hummer’s method. Oxoammonium salts (OS) were investigated to introduce nitroxide groups to GO, resulting in a one-step functionalization and exfoliation. The mechanisms of functionalization/exfoliation are proposed, where the oxidation of aromatic alcohols to ketone groups, and the formation of alkoxyamine species are suggested. Two kinds of functionalized graphene oxide layers (GOFT1 and GOFT2) were obtained by controlling the amount of OS added. GOFT1 and GOFT2 exhibited a high interlayer spacing (d0001 = 1.12nm), …

The Tornado Warning Process: A Review Of Current Research, Challenges, And Opportunities, Jerry Brotzge, William Donner

Sociology Faculty Publications

With the unusually violent tornado season of 2011, there has been a renewed national interest, through such programs as NOAA's Weather Ready Nation initiative, to reevaluate and improve our tornado warning process. This literature review provides an interdisciplinary, end-to-end examination of the tornado warning process. Following the steps outlined by the Integrated Warning System, current research in tornado prediction and detection, the warning decision process, warning dissemination, and public response are reviewed, and some of the major challenges for improving each stage are highlighted. The progress and challenges in multi-day to short-term tornado prediction are discussed, followed by an examination …

Decomposition Patterns And Nitrogen Dynamics Of Black Mangrove (Avicennia Germinans)Leaf Litter In Disturbed Estuaries Linked To The Lower Laguna Madre, Texas, Mario Alberto Marquez

Theses and Dissertations - UTB/UTPA

Estuaries are among the most productive aquatic systems in the world but are subject to both anthropogenic and natural disturbances. With increasing environmental concerns, efforts have become commonplace in assessing the status and trends of environmental conditions. In this study, an assessment of ecosystem status of various estuaries affected by different disturbances, was attempted through the examination of key functional processes such as leaf litter decomposition and nutrient dynamics during decay. Three estuaries located along the Brownsville Ship Channel near the southern terminus of the Lower Laguna Madre in Texas were studied. The overlying goal of this study was to …

On Closed Subsets Of Non-Commutative Association Schemes Of Rank 6, Jose Vera

Theses and Dissertations - UTB/UTPA

The notion of an association scheme is a generalization of the concept of a group. In fact, the so-called thin association schemes correspond in a well-understood way to groups. In this thesis, we look at the structure of non-commutative association schemes of rank 6. We will show that a non-normal closed subset of a noncommutative association scheme of rank 6, must have rank 2. The so-called Coxeter schemes of rank 6 which we present in Section 4 provide examples of association schemes of rank 6 with non-normal closed subsets of rank 2. It is shown that normal closed subsets of …

Design And Configuration Of Laser Tweezers Microscopy For Force Measurements On Single Dna Molecules, Carlos Jeziel Gonzalez Banuelos

Theses and Dissertations - UTB/UTPA

In this study, a detailed description of the optical tweezers microscopy technique is presented, as well as the methodologies used to prepare the DNA molecule for mechanical measurements at the nanoscale. The main objective is to initiate and extend the experimental biophysical studies on the DNA-proteins interactions at the University of Texas at Brownsville (UTB). DNA-binding proteins control almost all aspects of cellular function, such as transcription; chromosome maintenance, replication and DNA repair depend on the interaction of proteins with DNA. In view of such an important role played by DNA–protein interactions, various techniques have evolved over the years to …

Bilingual And Esl Pre-Service Teachers Learn About Effective Instruction For Ells Through Meaningful Collaboration, Alma D. Rodríguez

Bilingual and Literacy Studies Faculty Publications

This article presents the results of a study conducted to identify the perceptions of bilingual and ESL pre-service teachers regarding the integration of a collaborative service learning project in a key course of their teacher preparation program. Pre-, process, and final reflective essays were written by participants as they engaged in the development of an ESL unit to teach language through content to ELLs. The analysis of participants’ reflections revealed that preservice teachers connect the learning they acquire in their teacher education program with their life experiences, which contributes to their identity formation as prospective teachers of ELLs. In addition, …

E-Learning Tools For Andragogy: A Scale Model Of Technology-Based Active Learning, Ying Wang, Kai S. Koong, Jun Sun

Information Systems Faculty Publications

Andragogy is an educational philosophy on how to facilitate active learning for adult students. It requires instructors to engage students in various learning activities, including problem solving, essay writing, discussions, group projects, and so on. The challenge is how to facilitate student participation and assess learning outcomes. The emergence of e-learning tools, such as Discussion Board, Wiki, Blogs, and Wimba provide technical support for the new learning approach. Based on the review of information systems and education literature, this study develops a taxonomy of e-learning tools. In particular, it proposes a scale model based on the premise that e-learning tools …

The Pan American (2013-10-17), Norma Gonzalez, Lea Victoria Juarez

UTPA Archives - The Pan American Newspaper

Vol. 70, No. 8

The Collegian (2013-10-14), Cleiri Quezada

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 66, No. 8

The Pan American (2013-10-10), Norma Gonzalez, Lea Victoria Juarez

UTPA Archives - The Pan American Newspaper

Vol. 70, No. 7

A Green Chemoselective And Practical Approach Toward N-(2-Azetidinonyl) 25-Disubstituted Pyrroles, Debasish Bandyopadhyay, Elvira Rhodes, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Pyrrole and 2-azetidinone are two essential heterocyclic scaffolds, which are being broadly used in medicinal chemistry and drug discovery field. A green and practical method to synthesize novel N-(2-azetidinonyl) 2,5-disubstituted pyrroles, which are comprised of both pyrrole and 2-azetidinone moieties, has been developed. The classical Paal–Knorr reaction is one of the simplest and most economical methods for the synthesis of biologically important and pharmacologically useful pyrrole derivatives. The present procedure for the synthesis of N-(2-azetidinonyl) 2,5-disubstituted pyrroles (1,2,5-trisubstituted pyrroles) has been accomplished by reacting 3-amino β-lactams and 2,5-hexanedione in the presence of bismuth nitrate pentahydrate as an ecofriendly …