Digital Commons Network^™

Hydrogen Storage In Hypercrosslinked Polystyrene And Li-Mg-N-H Complex Hydride, Dervis Emre Demirocak

USF Tampa Graduate Theses and Dissertations

In this dissertation, hydrogen storage enhancement in hypercrosslinked polystyrene, effects of single walled carbon nanotubes (SWCNTs) supported ruthenium (Ru) catalyst on the kinetics and ammonia suppression in the LiNH2-MgH2 complex hydride system and the accuracy of hydrogen storage measurements are investigated in detail.

High surface area physisorption materials are of interest for room temperature hydrogen storage enhancement by spillover. Six different commercially available hypercrosslinked polystyrenes are screened by considering the specific surface area, average pore size, pore volume, and adsorption enthalpy. MN270 is selected mainly due to its high surface area and narrow pores for investigation of the spillover enhancement …

Modeling State Transitions With Automata, Egor Dolzhenko

USF Tampa Graduate Theses and Dissertations

Models based on various types of automata are ubiquitous in modern science. These models allow reasoning about deep theoretical questions and provide a basis for the development of efficient algorithms to solve related computational problems. This work discusses several types of automata used in such models, including cellular automata and mandatory results automata.

The first part of this work is dedicated to cellular automata. These automata form an important class of discrete dynamical systems widely used to model physical, biological, and chemical processes. Here we discuss a way to study the dynamics of one-dimensional cellular automata through the theory of …

The Underrepresentation Of African American Women Faculty: A Phenomenological Study Exploring The Experiences Of Mcknight Doctoral Fellow Alumna Serving In The Professoriate, Dionne Jones Ferguson

USF Tampa Graduate Theses and Dissertations

While African American women have been participating in higher education for more than a century, they remain significantly underrepresented among college and university professors in America. This study was pursued in an attempt to address the underrepresentation of African American women faculty at public and private universities within the State of Florida. More importantly, the study aimed to examine the role of the McKnight Doctoral Fellowship program (MDFP) in assisting McKnight Doctoral Fellow alumna in doctoral degree attainment, preparing them for the professoriate and contributing toward their professional success. A phenomenological methodological approach was used for this study, which was …

A Study Of Permutation Polynomials Over Finite Fields, Neranga Fernando

USF Tampa Graduate Theses and Dissertations

Let p be a prime and q = p^k. The polynomial g_n,q isin F_p[x] defined by the functional equation Sigma_{a isin Fq} (x+a)ⁿ = g_n,q(x^q- x) gives rise to many permutation polynomials over finite fields. We are interested in triples (n,e;q) for which g_n,q is a permutation polynomial of F_q^e. In Chapters 2, 3, and 4 of this dissertation, we present many new families of permutation polynomials in the form of g_n,q. The permutation behavior of g_n,q is becoming increasingly more …

The Effects Of Temporal Preparation On Reaction Time, Glen Robert Forester

USF Tampa Graduate Theses and Dissertations

When responding to external stimuli, preparation reduces Reaction Time (RT). One form of preparation known as temporal preparation results from advance knowledge about when a stimulus will appear. We used Event Related Potentials to investigate how increasing temporal preparation decreases RT during a speeded, choice RT task by manipulating temporal preparation within subjects. In order to determine which cognitive processes are speeded, the latencies of the Lateralized Readiness Potential (LRP) and P300 were examined across two levels of temporal preparation. In line with previous research the stimulus locked LRP, but not the response locked LRP, was speeded when temporal preparation …

Spatial And Temporal Trends Of Snowfall In Central New York - A Lake Effect Dominated Region, Justin Joseph Hartnett

USF Tampa Graduate Theses and Dissertations

Central New York is located in one of the snowiest regions in the United States, with the city of Syracuse, New York the snowiest metropolis in the nation. Snowfall in the region generally begins in mid-November and lasts until late-March. Snow accumulation occurs from a multitude of conditions: frontal systems, mid-latitude cyclones, Nor'easters, and most notably lake-effect storms. Lake effect snowfall (LES) is a difficult parameter to forecast due to the isolated and highly variable nature of the storm. Consequently, studies have attempted to determine changes in snowfall for lake-effect dominated regions. Annual snowfall patterns are of particular concern as …

Evaluation Of Four Portable Cooling Vests For Workers Wearing Gas Extraction Coveralls In Hot Environments, Joseph Kevin Johnson

USF Tampa Graduate Theses and Dissertations

Excessive exposure to heat stress can cause a host of heat-related illnesses. For laborers, job specific work demands and protective garments greatly increase the risk of succumbing to the effects of heat stress. Microclimate cooling has been used to control heat stress exposure where administrative or engineering controls are not adequate. This study tested the performance of four personal cooling vests for use with insulated protective clothing (gas extraction coveralls) in warm-humid (35 ° C, 50% relative humidity) and hot-dry (40°C, 30% relative humidity) conditions. On 10 separate occasions, 5 male volunteers walked on a treadmill to elicit a target …

Spin Dependent Transport In Novel Magnetic Heterostructures, Priyanga Buddhika Jayathilaka

USF Tampa Graduate Theses and Dissertations

Magnetic oxides have become of interest source for spin transport devices due to their high spin polarization. But the real applications of these oxides remains unsatisfactory up to date, mostly due to the change of properties as a result of nano structuring. Magnetite (Fe₃O₄) is one such a material. High Curie temperature and the half metallicity of Fe₃O₄ make it a good potential candidate for spin transport devices. Studies have shown that the nano structuring Fe₃O₄ changes most of it's important properties. This includes high saturation magnetization and drop of …

Bayesian Estimation Of Panel Data Fractional Response Models With Endogeneity: An Application To Standardized Test Rates, Lawrence Kessler

USF Tampa Graduate Theses and Dissertations

In this paper I propose Bayesian estimation of a nonlinear panel data model with a fractional dependent variable (bounded between 0 and 1). Specifically, I estimate a panel data fractional probit model which takes into account the bounded nature of the fractional response variable. I outline estimation under the assumption of strict exogeneity as well as when allowing for potential endogeneity. Furthermore, I illustrate how transitioning from the strictly exogenous case to the case of endogeneity only requires slight adjustments. For comparative purposes I also estimate linear specifications of these models and show how quantities of interest such as marginal …

Effect Of Solids Retention Time On The Denitrification Potential Of Anaerobically Digested Swine Waste, Maureen Njoki Kinyua

USF Tampa Graduate Theses and Dissertations

Three continuously stirred tank reactors (CSTR) were operated in semi continuous mode treating swine waste using anaerobic digestion. The reactors were used to test the effect of solid retention time (SRT) on CH4 yield, total ammonia nitrogen (TAN) concentrations, % volatile solids (VS), chemical oxygen demand (COD) and volatile fatty acids (VFA) removal, readily biodegradable COD concentration and the denitrification potential for the effluent in a biological nutrient removal (BNR) system. During Phase I of the study, the three reactors were operated at the same 28 day SRT for 16 weeks. SRTs were then changed during the 12 week Phase …

A Rheological Examination Of Polymer Composites: Including Functionalized Carbon Nanotubes, Viable Polyurethane Alternates, And Contact Lens Hydrogels, Bernard Knudsen

USF Tampa Graduate Theses and Dissertations

From medicine to aerospace, innovation in multiple fields will not occur without addressing current questions that still exist in polymer behavior and manipulation. This dissertation represents the research carried out over the course of three separate experiments using rheometry as the key technique to explore the behavior of polymer composites. In all three studies, polymer composites were investigated for changes to their known physical properties caused through the addition of a filler or functionalization.

Chapter Two examines the possibility of enhancing poly(4-methyl-1-pentene) through the use of soluble carbon nanotubes. In this series of experiments, carbon nanotubes were covalently functionalized using …

Do Personality Tests Have A Place In Academic Preparation Of Undergradute Hospitality Students, Gunce Malan

USF Tampa Graduate Theses and Dissertations

This is a descriptive study that poses the questions and discussion regarding use of personality tests in prediction of future job performance of the current undergraduate hospitality students. A gap exists between the perception of the skills and competencies of high performers and the perception of hospitality students (Berezina et al., 2011; Malan, Berezina & Cobanoglu, 2012). The purpose of this study is to investigate if personality tests will help in predicting the success of students in their preferred job setting as compared to current high performers (managers).

The use of personality tests increased substantially after 1988, when the government …

Biochemical Aspects Of The Thermal Sensitivity And Energy Balance Of Polar, Tropical And Subtropical Teleosts, Eloy Martinez

USF Tampa Graduate Theses and Dissertations

The maintenance of a functional energy balance in ectothermic fauna could be challenging in a thermally disparate environment. Biochemical adaptations at the enzyme and membrane levels allows for a set compensatory mechanism that allow the individual to maintain an energetic surplus, thus allocating energy for growth and reproduction. The present work describes how the energetic machinery in the cell, particularly the mitochondrion, could be affected by temperature changes. More specifically, this work aimed to determine how environmental temperature affects the mitochondria energetic performance of fishes from disparate thermal regimes.

Mitochondrial ATP production efficiency was evaluated in fishes from polar, tropical …

Reaction Enthalpy And Volume Profiles For Excited State Reactions Involving Electron Transfer And Proton-Coupled Electron Transfer, William Antonio Maza

USF Tampa Graduate Theses and Dissertations

Electron transfer, ET, and proton-coupled electron transfer, PCET, reactions are central to biological reactions involving catalysis, energy conversion and energy storage. The movement of electrons and protons in either a sequential or concerted manner are coupled in a series of elementary reaction steps in respiration and photosynthesis to harvest and convert energy consumed in foodstuffs or by absorption of light into high energy chemi-cal bonds in the form of ATP. These electron transfer processes may be modulated by conformational dynamics within the protein matrix or at the protein-protein interface, the energetics of which are still not well understood. Photoacoustic calorimetry …

Development Of Novel Nano-Composite Membranes As Introduction Systems For Mass Spectrometers: Contrasting Nano-Composite Membranes And Conventional Inlet Systems, Luis Miranda

USF Tampa Graduate Theses and Dissertations

This dissertation presents the development of novel nano-composite membranes as introduction systems for mass spectrometers. These nano-composite membranes incorporate anodic aluminum oxide (AAO) membranes as templates that can be used by themselves or modified by a variety of chemical deposition processes. Two types of nano-composite membranes are presented. The first nano-composite membrane has carbon deposited within the pores of an AAO membrane. The second nano-composite membrane is made by coating an AAO membrane with a thin polymer film. The following chapters describe the transmission properties these nano-composite membranes and compare them to conventional mass spectrometry introduction systems. The nano- composite …

Reliability Assessment Of Ion Contamination Residues On Printed Circuit Board, Minh Tam Tran Nguyen

USF Tampa Graduate Theses and Dissertations

Ion contaminants from Printed Circuit Board (PCB) assembly processes pose a high reliability risk because they result in damaged circuits. Therefore, it is essential to understand the level of ionic species on the electronic circuitry as well as the reliability risks caused by these contaminants. There are a number of approaches available in the industry to assess the reliability risks ; for example, the water drop test (WDT) is one of the techniques used to determine the propensity of an ionic contaminant to cause electrical short failures by dendrite formation. The objective of this research is to determine the time …

Dynamic Processes In Network Goods: Modeling, Analysis And Applications, Arnut Paothong

USF Tampa Graduate Theses and Dissertations

The network externality function plays a very important role in the study of economic network industries. Moreover, the consumer group dynamic interactions coupled with network externality concept is going to play a dominant role in the network goods in the 21st century. The existing literature is stemmed on a choice of externality function with certain quantitative properties. The utility function coupled with the network externality function is used to investigate static properties of rational equilibrium. The aim of this work is to systematically initiate a development of quantitative effects of the concept of network externality and its influence on the …

The Effects Of Fractures On The Occurrence And Distribution Of Arsenic In The Upper Floridan Aquifer During Aquifer Storage And Recovery, William Charles Hutchings

USF Tampa Graduate Theses and Dissertations

ABSTRACT

Aquifer storage and recovery (ASR) is used world-wide to supplement available water supplies by storing surplus water in aquifers and recovering it during periods of drought and increased demand. The use of ASR as an option for increasing available municipal irrigation and fresh water supplies is threatened as a result of the mobilization of arsenic in some aquifers during ASR. Arsenic is liberated from arsenic-bearing sulfide minerals as a result of the mixing of oxidizing injected water with reducing insitu groundwater. Fracture networks can have significant influence on the migration and distribution of arsenic in the Upper Floridan Aquifer …

Design, Synthesis, Processing, And Thermal Analysis Of Nanocomposites With Tunable Properties, Mu Seong Kim

USF Tampa Graduate Theses and Dissertations

Polymer composites containing nanosized fillers have generated explosive interest since the early 1980's. Many recent studies have been conducted incorporating nano-fillers into polymer matrices to design and synthesize materials with tunable mechanical, thermal, and optical properties. Conventional filled polymers, where the reinforcement is on the order of microns, have been replaced by composites with discrete nanosized fillers. Gradually, theories that predicted that composite properties are independent of particle size in the micron range were challenged by nanocomposites. Rather, nanocomposite properties are greatly influenced by the surface area of the. All of this is complicated by the fact that nanoparticles are …

Assessment Of Student Achievement In Introductory Physical Geology: A Three -Year Study On Delivery Method And Term Length, Marianne O'Neal Caldwell

USF Tampa Graduate Theses and Dissertations

Physical Geology is a popular general education course at Hillsborough Community College (HCC) as at many other colleges and universities. Unlike many science courses, most students taking Physical Geology are not majoring in a STEM (Science, Technology, Engineering, and Mathematics) discipline. Typically most students enrolled in Physical Geology are majoring in business, education, or pursuing a general A.A degree for transfer to a four-year university. The class is likely to be one of the few, if not the only, physical science classes that many of these students will take in their academic career. Therefore, this class takes on increased importance, …

Design, Synthesis And Evaluation Of Novel Diazirine Photolabels With Improved Ambient Light Stability And Fluorous-Based Enrichment Capacity, Arun Babu Kumar

USF Tampa Graduate Theses and Dissertations

Photoaffinity labeling is a quintessential technique in studying and analyzing the interaction between a ligand and receptor. Diazirines are one of the important photo-labile moieties used in photoaffinity labeling due to their superior photo labeling characteristics. Herein, we report the investigations we conducted with diazirine photolabels on (a) photochemical aspects leading to enhancement of their ambient light stability and (b) equipping them with fluorous tags to enable fluorous enrichment of labeled proteins. Furthermore, we report a pilot study to develop BACE-1 inhibitors, which have potential to be developed into photoaffinity probes.

3-Trifluoromethyl-3-phenyldiazirine offers good selectivity and protection against pseudolabeling but …

A Geochemical Analysis Of Fulgurites: From The Inner Glass To The Outer Crust, Michael L. Joseph

USF Tampa Graduate Theses and Dissertations

Cloud-to-ground lightning strikes produce natural glasses on the surface of the Earth, called fulgurites. These natural glasses are tubular in shape with a central void surrounded by an inner glass, and the inner glass is surrounded by an outer crust or toasted region. Previous studies report different kinds of melts existing in several different types of fulgurites; however, little to no chemical data has been collected that tracks chemical variations from the inner glass to the outer crust of a fulgurite. This study uses microprobe and laser ablation inductively coupled plasma mass spectrometer analytical techniques to collect transects of chemical …

Sediment Transport And Distribution Over Continental Shelves: A Glimpse At Two Different River-Influenced Systems, The Cariaco Basin And The Amazon Shelf., Laura Lorenzoni

USF Tampa Graduate Theses and Dissertations

The aim of this dissertation was to understand lithogenic suspended sediment transport mechanisms and distribution in two river-influenced margins: The Cariaco Basin, Venezuela, and the Amazon Shelf, Brazil. Lithogenic sediment input in the Cariaco Basin is controlled by small mountainous rivers (SMR), while in the Amazon Shelf it is dominated by the Amazon River, the largest river in the world in terms of freshwater discharge (~20% of global riverine discharge). Optical transmissometer measurements were coupled with particulate organic matter (POM) observations to understand changes in the geochemical composition of suspended sediment and spatial/temporal distributions over the two regions of interest. …

N-Acyl Ciprofloxacins: Synthesis, Antibacterial Activity And Effects On Molecular Loading Of Poly(Vinyl Benzoate) Nanoparticles, Ryan Cormier

USF Tampa Graduate Theses and Dissertations

Bacterial infections are becoming progressively more difficult to treat due to antibiotic resistance and the decreasing rate at which new antibiotics are brought to market. The Turos laboratory has attempted to tackle this problem for the last 15 years with the discovery of N-thiolated β-lactams leading to the design of polyacrylate nanoparticles to deliver these and other drugs. Chapter 1 discusses many reported instances of utilizing different types of polymeric nanoparticles to deliver antibiotics. Poly(lactic-co-glycolic acid) (PLGA), poly(alkyl cyanoacrylate) (PACA), poly(styrene-co-butylacrylate), and chitosan are the main polymers used to make nanoparticles. Chapter 2 describes the synthesis, antibacterial activity, and mechanism …

The Effects Of Cognitive Stimulation And Computerized Memory Training Among Older Adults Residing In Indepedent-Living Facilities, Elizabeth M. Hudak

USF Tampa Graduate Theses and Dissertations

Background: With age, older adults experience declines in both short- and long-term memory. One way to counter these age-related declines is through memory interventions which include computerized cognitive training and non-computerized cognitive stimulation. This dissertation examined whether a cognitive training program, Dakim BrainFitness (Dakim Inc., 2002) and a program of cognitive stimulation, Mind Your Mind (Seagull & Seagull, 2007), enhance memory performance among cognitively-intact older adults residing in independent-living retirement communities. Specifically, the following research questions were proposed: (a) How effective is the computerized cognitive training program in improving memory performance relative to the cognitive stimulation program or a no-contact …

Investigating The Status Of Early Numeracy Skills In Bilingual Dual Language Learner Latino Children Attending Head Start And The Association With Parent Demographic Characteristics, Chavely Lissette Iglesias

USF Tampa Graduate Theses and Dissertations

Research on mathematics achievement has become increasingly important with today's technological advances and demand for specialized knowledge. Though there is much literature regarding mathematics achievement in monolingual speakers, little is known regarding the mathematical abilities of Dual Language Learner (DLL) Latino children. This study examined the early numeracy skills in English and Spanish of 132 DLL Latino children attending Head Start programs in five counties across Florida. Relationships and differences among their performance in both languages were examined, along with the contribution of specific parent demographic variables to math achievement. Findings indicated that DLL Latino Head Start children's performance on …

Production Of Bioactive Secondary Metabolites By Florida Harmful Bloom Dinoflagellates Karenia Brevis And Pyrodinium Bahamense, Cheska Burleson

USF Tampa Graduate Theses and Dissertations

Despite the critical role algae serve as primary producers, increases or accumulation of certain algae may result in Harmful Algal Blooms (HABs). Algal toxins from these blooms contribute significantly to incidences of food borne illness, and evidence suggests HABs are expanding in frequency and distribution. Mitigation of these HABs without knowledge of the ecological purpose and biochemical regulation of their toxins is highly unlikely. The production, function, and potential of secondary metabolites produced by the dinoflagellates Karenia brevis and Pyrodinium bahamense, were investigated.

Brevetoxins were demonstrated by two different methods to localize within the cytosol of Karenia brevis. …

The Walls Are Closing In: Comparing Property Crime Victimization Risk In Gated And Non-Gated Communities, Nicholas Branic

USF Tampa Graduate Theses and Dissertations

In recent years, a growing proportion of the population has moved into gated communities in response to an increasingly pandemic fear of crime. While a sizable body of research has addressed fear of crime and perceived safety in gated communities, few studies have investigated actual rates of victimization. The studies that do compare victimization in gated and non-gated communities tend to be localized assessments and present mixed findings on the effectiveness of community gating as a form of protection from crime.

The present study utilizes a cross-section of National Crime Victimization Survey data to investigate the micro-level effects of living …

Investigation Of Stress Changes At Mount St. Helens, Washington, And Receiver Functions At The Katmai Volcanic Group, Alaska, With An Additional Section On The Assessment Of Spreadsheet-Based Modules., Heather L. Lehto

USF Tampa Graduate Theses and Dissertations

Forecasting eruptions using volcano seismology is a subject that affects the lives and property of millions of people around the world. However, there is still much to learn about the inner workings of volcanoes and how this relates to the chance of eruption. This dissertation attempts to increase the breadth of knowledge aimed at helping to understand when a volcano is likely to erupt and how large that eruption might be. Chapters 2 and 3 focus on a technique that uses changes in the local stress field beneath a volcano to determine the source of these changes and help forecast …

Human Motion Tracking For Assisting Balance Training And Control Of A Humanoid Robot, Ahmad Adli Manasrah

USF Tampa Graduate Theses and Dissertations

Abstract

This project illustrates the use of the human's ability to balance according to his center of gravity as demonstrated in two applications. The center of gravity of a human is explained in detail in order to use it in controlling the Aldebaran NAO robot and in the robot-assisted balance training.

The first application explains how a humanoid robot can mimic a human's movements via a three dimensional depth sensor where the sensor analyzes the position of a user's limbs and how the robot can lift one foot and balance on the other by redistributing the its body mass when …