Physical Sciences and Mathematics Commons^™

Removal Of Cobalt And Nickel From Water Using Mno2 And Mn3o4 Nanomaterials, Maria Dolores Pacheco

Theses and Dissertations - UTB/UTPA

Nanomaterials MnO2 and Mn3O4 were synthesized using a titration/precipitation technique and characterized with powder XRD. A pH assay determined the optimum binding for cobalt and nickel occurred at pH 5 for both nanomaterials. A time dependency study determined that cobalt and nickel required more time with MnO2 for maximum adsorption than Mn3O4. The binding capacity study showed cobalt and nickel have good binding capacity with both nanomaterials. Interfering ion assay in the presence of Na+ , Ca2+ and Mg2+ showed minimal difference in the adsorption of cobalt and nickel to MnO2 or Mn3O4. Cobalt and nickel showed a reduction in …

Effect Of Crimping, Multilayering, And Twisting On Polymer Fibers For Acl Replacement, Mariana Ocampo

Theses and Dissertations - UTB/UTPA

The Anterior Cruciate Ligament (ACL) is the most common knee injury in the United States; roughly 150,000 ACL surgeries are performed annually. The ACL lacks self-healing properties due to its location inside the knee’s intra – articular environment (IA). Treatments for ACL ruptures involve the use of autogenous grafts or allografts. More suitable treatments can be found in new bio engineered tissue scaffolds, composed of natural and synthetic polymers. The polymers provide stronger mechanical properties and the ability to promote cell adhesion. It is believed that mimicking the crimping pattern of human ligaments will enhance polymer properties. Four polymers were …

Oxidation Of Dibenzothiophene To Dibenzothiophene-Sulfone Using Molybdenum (Vi) Oxide, Tungsten (Vi) Oxide, And Ratios Of Molybdenum (Vi) Oxide And Tungsten (Vi) Oxide At Atomspheric Pressure, Sean M. Pelfrey

Theses and Dissertations - UTB/UTPA

This is a study of the catalytic oxidation of dibenzothiophene to dibenzothiophene sulfone using molybdenum (VI) oxide, tungsten (VI) oxide, and mixtures of molybdenum (VI) oxide and tungsten (VI) oxide at atmospheric pressure. The oxidative desulfurization reaction is studied with respect to the kinetics and thermodynamics of the process. Five catalysts were synthesized using a precipitation reaction. The five catalysts were 100% MoO3, 75/25% MoO3/WO3, 50/50% MoO3/WO3, 25/75% MoO3/WO3, and 100% WO3. Each catalyst was calcinated at three different temperatures 250oC, 500oC, 750oC and characterized using X-Ray Diffraction. Reactions of DBT-catalyst were held, under reflux, at temperatures from 140 oC …

Sign Me Up! Determining Motivation For High School Chemistry Students Enrolling In A Second Year Chemistry Course, Nilda N. Camarena

Theses and Dissertations - UTB/UTPA

A sample of 108 Pre-AP Chemistry students in Texas participated in a study to determine motivational factors for enrolling in AP Chemistry and University Chemistry. The factors measured were academic attitude, perceptions of chemistry, confidence level in chemistry, and expectations/experiences in the chemistry class. Students completed two questionnaires, one at the beginning of the year and one at the end. Four high school campuses from two school districts in Texas participated. Two campuses were traditional high schools and two were smaller magnet schools. The results from this study are able to confirm that there are definite correlations between academic attitudes, …

Monitoring Citrus Nutrition In The Rio Grande Valley For Fertilizer Recommendations, Iram Lopez

Theses and Dissertations - UTB/UTPA

Soil fertility and plant nutrition is crucial for a better yield and consistent harvest in the Rio Grande Valley for local farmers growing citrus trees. A field of oranges and a field of grapefruits were monitored and nutrition deficiencies were noticed that played an important role during fruit set. Soil samples that were taken throughout the year were analyzed via a carbon dioxide extraction method that mimics the way plants naturally take up nutrients or extract nutrients from every soil type. Macronutrients such as the N, P, K, Na, Ca, Mg and some of the micronutrients (Zn, Fe, Mn, and …

Cloning And Characterization Of Ef-Tu And Ef-Ts From Streptococcus Pneumoniae, Carlos Eduardo Rivera

Theses and Dissertations - UTB/UTPA

Antibiotic resistance is a prevalent threat to public health around the world, and resistance among strains of Streptococcus pneumoniae is growing rapidly. This increasing resistance elevates the demand for new drug discoveries. This research attempts to develop a means to combat S. pneumoniae by targeting protein synthesis for the discovery of new antibacterial agents. Protein synthesis components, elongation factor Tu (EF-Tu) and elongation factor Ts (EF-Ts) facilitate many steps in the biosynthesis of proteins and are therefore essential proteins involved in protein synthesis. EF-Tu and EF-Ts were cloned, expressed, purified, and enzymatically characterized to help develop a screening system that …

Metal Oxide Nanostructures For Energy Conversion And Storage, Xing Sun

Theses and Dissertations - UTB/UTPA

With the depletion of non-renewable resources and the related problems such as environmental pollutions and global warming effect, the society urgently needs more efficient and controllable energy conversion and storage systems. Three-dimensional ZnO nanoforests were prepared and morphology-tunable, which benefits both of energy conversion and storage systems. Willow-like ZnO nanoforests led the highest conversion efficiency of photoelectrochemical water splitting in reported pure ZnO nanostructures. Compared with nanowire arrays, ZnO@MnO2 nanoforests delivered 5 times higher specific capacitances within the same footprint area. V2O5@PPy exhibited higher specific capacitance and better rate stability than pure V2O5 nanofibers. This work lays the foundation for …

A Screening Platform For Identification Of Compounds That Inhibit Protein Synthesis In Pseudomonas Aeruginosa, Yanmei Hu

Theses and Dissertations - UTB/UTPA

Pseudomonas aeruginosa is a Gram-negative pathogenic bacteria and a common cause of nosocomial infections. This pathogen has recently garnered attention due to its pan-resistance. We have developed a poly(U) mRNA-directed aminoacylation/translation (A/T) protein synthesis system from P. aeruginosa. The concentration of each component of the system has been arrived at through multiple rounds of optimization. Poly-phenylalanine synthesis in the system was monitored using scintillation proximity assays (SPA). This system has been used to screen two natural compound libraries (>1100) and a number of the compounds that inhibit greater than 50% of the activity of the system have been identified. …

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 …

Remediation Of Copper(Ii) And Lead(Ii) From Aqueous Solution Using Engineered Iron Oxide And Manganese Oxide Nanomaterials, Carlos Tamez Jr.

Theses and Dissertations - UTB/UTPA

Nano-sized Fe3O4, Fe2O3, Mn3O4, and MnO2 were synthesized by titration/precipitation and characterized using powder XRD. pH assays determined that optimum binding occurred at pH 4 for Fe3O4 and Fe2O3 and pH 3 for Mn3O4 and MnO2. Maximum adsorption of Cu(II) and Pb(II) occurred within 20 min or less of contact with the nanomaterials. The synthesized nanomaterials showed a binding preference for Pb(II) over Cu(II) at concentrations above 50 ppm. Batch studies also showed no significant reduction in the binding of copper and lead to either Fe3O4, Fe2O3, Mn3O4, or MnO2 in the presence of Na+ , K+ , Mg2+ or …

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 …

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 …

Biological Compatibility And Cytotoxicity Studies Of Hepa-1c1c7, Hepg2, And Mcf-7 Cancer Cell Lines Upon Exposure To Silver, Palladium, And Gold Nanoparticles, M. Esther Salinas

Theses and Dissertations - UTB/UTPA

The field of nanomedicine has recently explored potential applications for cancer treatment ranging from drug delivery methods to cancer imaging techniques. Due to potential risks of nanomaterials affecting non-cancerous cells in the body, in vitro toxicity studies are being conducted. The nanoparticles (NPs) were synthesized from potassium tetrachloroaurate (III) hydrate, potassium tetrabromoaurate (III) dihydrate, potassium tetrachloropalladate (II), and silver nitrate. NPs were synthesized using the Turkevich method or through the sodium borohydride reduction. Particles synthesized using sodium borohydride were stabilized with cetyltrimethylammonium bromide (CTAB). The NPs under investigation were used to treat three cancer cell lines. The treated cells were …

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 …

I. Norbornene As Organocatalyst: Unusual: Amination Ii. Stereoselective Synthesis Of 3, 4 Di-Substituted Β-Lactams; Classical Vs Microwave Method, Ravi Reddaboyna

Theses and Dissertations - UTB/UTPA

I. Amine functionality is important in the preparation of biologically active and industrially useful molecules. Many approaches to form C―N bonds provide access to fine chemical building blocks, pharmaceuticals, agrochemicals, and surfactants. Microwave irradiation is a highly recommended ecofriendly approach for the synthesis of medicinally important compounds. Organic catalysis is important segment in the field of organic chemistry, for the synthesis of many complex molecules by providing a number of advantages.

II. Cancer refers to a large group of diseases characterized by uncontrolled cell multiplication and the ability of these cells to enter other tissues and spread to other parts …

Electrospinning Nanofibers For Controlled Drug Release, Indrani Banik

Theses and Dissertations - UTB/UTPA

Electrospinning is the most widely studied technique for the synthesis of nanofibers. Electrospinning is considered as one of the technologies that can produce nanosized drugs incorporated in polymeric nanofibers. In vitro and in vivo studies have demonstrated that the release rates of drugs from these nanofiber formulations are enhanced compared to those from original drug substance. This technology has the potential for enhancing the oral delivery of poorly soluble drugs [1]. The electrospun mats were made using Polycaprolactone/PCL, Poly(DL-lactide)/PDL 05 and Poly(DL-lactide-co-glycolide)/PLGA. The drugs incorporated in the electrospun fibers were 5-Fluorouracil and Rapamycin. The evidence of the drugs being embedded …

Synthesis And Luminescence Properties Of Core-Shell Structured (Lanthanum(1-X)Europium(X))(2)Zirconium Heptoxid[At]Yttrium Orthoborate Spherical Nanoparticles, Suresh Babu Alaparthi

Theses and Dissertations - UTB/UTPA

Many rare earth compounds have photoluminescent characteristics for various important applications. In this study, europium doped La2Zr2O7 nanoparticles were first synthesized morphology-controllably by using a molten-salt synthesis method. These nanoparticles were used as the core for coating with YBO3 shell. We then explored the effect of different experimental processing parameters, such as annealing temperatures, reaction times and different ratios of salt mixtures on the structure and morphology of these nanoparticles. The overall core size and shell thickness can be controlled by varying the reactant concentration both the core and shell material. These core@shell nanoparticles were then characterized mainly using power …

Synthesis And Characterization Of Biodegradable Electrospun Polyurethanes For Biomedical Applications, Xujun Zhang

Theses and Dissertations - UTB/UTPA

Two types of polyesters [(Poly(ε-caprolactone) and Poly(δ-valerolactone)] were synthesized by ring-opening polymerization with diethylene glycol as a initiator and stannous octate as a catalyst. The corresponding polyurethanes were synthesized by two-step polymerization with 1,4-diisocyanate butane (BDI) and reacted with 1,4-diamino butane (Putrescine) chain extender. The polymers were characterized by Proton Nuclear Magnetic Resonance (1H NMR), Fourier Transform Infrared Spectroscopy (FT-IR), Raman Spectroscopy, Size-exclusive Chromatography (SEC), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The resulting polyurethanes were fabricated into nanofibers using an electrospinning technique. The morphological, structural characterizations and thermal properties of the bulk polyurethanes and electrospun polyurethanes nanofibers were …

Synthesis Of Novel Bis-Β-Lactams, Jocabed Marquez

Theses and Dissertations - UTB/UTPA

This study presents the synthesis and structure of newly discovered β-lactams and the mechanism of their synthesis via the Staudinger reaction. β-lactams known as 2-azetidinones, are four membered cyclic amides that have been extensively used and recognized as the central motif of the β-lactam antibiotics, the most widely employed family of antimicrobial agent to date. The Staudinger reaction involves the cycloaddition between an acid chloride with an imine, in presence of a tertiary base. The possibility of cooperative effects from two therapeutic functionalities in drug molecules, has prompted interest in the synthesis of Bis-β-lactams. The synthesis of 2 novel Bis-β-lactams …

Microwave-Induced Bismuth Nitrate-Catalyzed Multicomponent Reaction Toward Heterocycles, Ashwini Bobbala

Theses and Dissertations - UTB/UTPA

The microwave-induced reaction for the synthesis of nitrogen containing heterocyclesis very important in medicinal chemistry. The synthesis of various other valuable compounds is also done by employing this reaction. The aza Diels-Alder reaction is one of the most powerful synthetic tools for the synthesis of nitrogen containing heterocycles. The main goal of the research is to synthesize the nitrogen containing heterocycles using Bismuth nitrate as the catalyst in the presence of microwave irradiation. In the present study we explore the catalytic activity of bismuth nitrate and the role of microwave reactor in the synthesis of 2, 3-diaryl substituted bicyclic octanone …

Electrospun Biocompatible Polyurethanes With The Addition Of Multi-Walled Carbon Nanotubes, Travis Cantu

Theses and Dissertations - UTB/UTPA

Three different Polyurethanes (PUs) Lycra®, HydroThaneTM, and BioSpan®, were electrospun and characterized using Scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform-infrared spectroscopy (FTIR), & Raman spectroscopy. Nanofiber composites were made by incorporating MWCNTs at three different concentration 0.1wt% 0.5wt% and 1.0wt% to the three PUs. These samples were characterized and mechanical and thermal test were done. The TEM images showed MWCNT bundling in the polymer matrix at the highest concentration, the FTIR showed shifts in characteristic urethane bands indicating an interaction with the polymer and MWCNTs. Mechanical test showed a decrease in the Young’s modulus (E’) in most …

Development Of An Assay To Screen For Novel Proteins From Bacillus Thuringiensis With Antibacterial Activity, Auriole T. Tamegnon

Theses and Dissertations - UTB/UTPA

Bacillus thuringiensis (Bt) produces the non specific Cyt protein and the specific Cry protein. Past research has shown these proteins are toxic to insects, red blood cells, cancer cells, and some bacteria. While many antibacterial substances are known to exist, efforts to find new ones still continue. In this project we used Bt 6-2-56 (containing a novel filament associated parasporal body which appears non-toxic to insects and protozoan) and Bt 4Q13 (which has been shown to have activity against E. coli and S. aureus) to develop a simple, easy, scalable assay in a 96 well Microtitre plate to look for …

Chemical Education Experiences From The English Language Learner Perspective, Annette Flores

Theses and Dissertations - UTB/UTPA

The Rio Grande Valley (RGV) is a region populated by Spanish-speaking immigrants and their descendants producing a large English Language Learner (ELL) student population. ELLs have historically had low literacy rates and achievement levels when compared to their counterparts. In order to address this achievement gap, previous research efforts and curriculum interventions have focused on language acquisition as being the determining factor in ELL education, with little attention given to academic content acquisition. More current research efforts have transitioned into English language acquisition through academic content instruction; this present research study specifically focuses on ELL experiences in chemistry. Participants were …

Creation Of Post Ap Chemistry Class, Julian Medrano

Theses and Dissertations - UTB/UTPA

The creation of a Post AP Chemistry Class to be taught at the high school level for grade 12 students is discussed. The class is to be taught under the supervision of the University of Texas Pan American professors and taught by an MS Chemistry teacher, in order to better transition students into upper level chemistry courses beyond Chemistry 1401 and 1402.

Synthesis And Characterization Of 4,4-Prime-Distyrylbiphenyl And Its Applications In Organic Field Effect Transistors, Nestor A. Santos Jr.

Theses and Dissertations - UTB/UTPA

4,4’-distyrylbiphenyl (DSBP), an ambipolar small molecule with electroluminescent properties, was synthesized following two synthetic protocols. Accordingly, biphenyl was bromomethylated using a mixture of paraformaldehyde and hydrogen bromide in 20% to 60% isolated yields. Bromomethylated biphenyl was then reacted with triphenyl phosphine, or with triethyl phosphate to yield the corresponding triphenyl phosphonium bromide or triethyl phosphonate, respectively. DSBP was synthesized by reaction of the triphenyl phosphonium bromide or triethyl phosphonate with freshly distilled benzaldehyde according to the Wittig, or Horner-Wadsworth-Emmons protocols. DSBP from the Wittig reaction resulted in a mixture of cis-trans isomers, while the product from the Horner-Wadsworth-Emmons reaction yielded …

Biocompatibility Of Electrospun Polymer Nanofibers (Epns) With Nih 3t3 Cell Line And Interaction Of Quercetin With Different Flavonoids: Induction Of Phase Ii Enzymes In Vitro Cancer Cell Lines, Brenda S. Benavides

Theses and Dissertations - UTB/UTPA

Part I: In this study Electrospun nanofibers, Elasthane™ 55D, Elasthane™ 75D, Biospan®, Hydrothane™ and Lycra® were evaluated for their biocompatibility to be artificial tissue substitutes using NIH-3T3 fibroblast cells. A colorimetric based MTT dye reduction assay demonstrated that EPNs did not stop cell growth in vitro. Additionally, fluorescence confocal microscope images verified that cell adhesion occurred in the nanofibers, and cell growth on the EPNs over two weeks period was confirmed by DNA quantification.

Part II: This section of the thesis is focused on evaluation of chemopreventive properties of various phytochemicals by induction of Phase II enzymes. The interaction of …

Bismuth Nitrate-Induced Novel Nitration Of Eugenol And Estradiol: An Exploratory Study, Luis Canales

Theses and Dissertations - UTB/UTPA

Molecules originating in nature have held an important place in chemistry and in society. Many of the important useful compounds of all time were first discovered in nature. Eugenol, a multi-functionalized biologically active constituent, is present in high quantity in natural clove. Eugenol is an important herb due to its medicinal activities; therefore, research on this molecule is necessary. Nitration of Eugenol was performed through various metal nitrates and solid surface combinations. Estrogens are contributors of the development of many secondary sex characteristics in females; they play various important roles in the nervous system. Direct nitration of estradiol has been …

Spectral Reflectance As An Indicator Of Foliar Concentrations Of Arsenic In Common Sunflower (Helianthus Annuus), Yuridia Patricia Peralta De Gandy

Theses and Dissertations - UTB/UTPA

Studies were conducted to investigate the use of spectral reflectance by foliage of common sunflower as a potential indicator of arsenic contamination of soil. Germination method was developed for sunflower seeds, and cohorts of sunflower seedlings in hydroponic tanks were established. The cohorts were exposed to 0 ppm, 5 ppm, 7.5 ppm, and 10 ppm treatments of As (V) and reflectance measurements of foliage were collected using a spectroradiometer during two experiments.Results demonstrated the feasibility of using spectral reflectance by foliage of common sunflower as a potential indicator of arsenic contamination. In both experiments, arsenic concentrations in leaf tissues were …

Study On Energy Absorption Behaviors Of Hydrophobic Mesoporous Materials, Zhongyuan Sun

Theses and Dissertations - UTB/UTPA

Nanoporous energy absorption system has been developed tremendously as an advanced energy storage system in recent years. This research is to optimize the mesoporous energy absorption matrixes via surface treatment to find out the optimum conditions for higher energy conversion efficiency. Five mesoporous silica matrixes with pore size in a range of 3 to 31.6 nm were investigated. Six alkylchlorosilanes were used as the modification reagents. The results showed that the energy absorption density via pressure-induced infiltration is as high as 8.0 J/g which is 100 times larger than that of conventional energy absorption materials. The controllability of the energy …

A Proposal For The Mechanism Of The Iron-Ascorbate, Fenton, And Hydroxyl Radical-Quenching Series, Jonathan Velasco

Theses and Dissertations - UTB/UTPA

The Fenton reaction between [Fe(II)] and [HOOH] is observed in the presence of ascorbic acid, [AscH-], during [Fe(III)] and HO• reduction; this is done as part of consecutive redox reactions between [Fe(III)] and [Fe(II)]. As a result, the rate orders with respect to [Fe(III)], ascorbic acid, and [HOOH] are of (approximately) 2nd, 1st, and 4 th order, respectively. However, the rate constants for each reaction in this study show patterns when measured against solution pH; empirically, reactions proceed faster at smaller pH and vice versa.