UNT Theses and Dissertations - 17,975 Matching Results

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Consequences of Coworker Bullying: A Bystander Perspective

Description: Previous research on workplace bullying primarily focuses on two main actors – the bully and the victim – while neglecting a third actor: the bystander of the bullying. The prevalence of workplace bullying is increasing across organizations, resulting in more employees becoming subjected to the effects of workplace bullying. Furthermore, witnessing coworker-on-coworker bullying is likely to influence the relationships that the bystander has with the two coworkers involved in the bullying episode. Two areas are proposed to investigate their effect on the coworker bystander: coworker interpersonal justice and personal identification with coworkers. Coworker interpersonal justice involves the perceived fairness between coworkers, while personal identification refers to how these bystanders identify with the specific actors of the bullying event. In addition to work-related outcomes, bystanders are affected at a personal level. That is, being exposed to bullying situations causes these bystanders to alter their anxiety levels and their core affect, with core affect being a precursor to moods and emotions. In addition to the aforementioned outcomes of witnessing a coworker bullying incident, there are also contextual aspects which may influence these relationships. Personal-level factors, such as a bystander's empathy and sense of coherence (i.e., coping mechanisms), may influence the effect of witnessing a coworker being bullied. Similarly, the gender of the victim in relation to the gender of the bystander may also play a role. Using affective events theory, I investigate how witnessing coworker bullying in the workplace effects bystanders. This research employs a 2 x 2 experimental design with multi-wave data collection and an in-person lab session to test the proposed hypotheses. AET is operationalized by creating a fictional coworker bullying situation in which observers are either exposed to the bullying situation or not. This research offers several contributions to the management literature as well as to practitioners. First, it ...
Date: May 2017
Creator: Medina, Michele Nicole
Partner: UNT Libraries

Construct Validation and Measurement Invariance of the Athletic Coping Skills Inventory for Educational Settings

Description: The present study examined the factor structure and measurement invariance of the revised version of the Athletic Coping Skills Inventory (ACSI-28), following adjustment of the wording of items such that they were appropriate to assess Coping Skills in an educational setting. A sample of middle school students (n = 1,037) completed the revised inventory. An initial confirmatory factor analysis led to the hypothesis of a better fitting model with two items removed. Reliability of the subscales and the instrument as a whole was acceptable. Items were examined for sex invariance with differential item functioning (DIF) using item response theory, and five items were flagged for significant sex non-invariance. Following removal of these items, comparison of the mean differences between male and female coping scores revealed that there was no significant difference between the two groups. Further examination of the generalizability of the coping construct and the potential transfer of psychosocial skills between athletic and academic settings are warranted.
Date: May 2017
Creator: Sanguras, Laila Y
Partner: UNT Libraries

A Constructional Approach to Establishing and Maintaining Calm Canine Behavior

Description: Very few behavior-change programs with canines produce effects that persist beyond the training condition. The present study is an experimental demonstration of a constructional program that established calm patterns of behavior as alternatives to hyperactive ones. Three dogs that exhibited hyperactive patterns were chosen as subjects. Seven conditions common to canine-caretaker relationships were used to determine which factors resulted in the hyperactive patterns. Then, sitting and lying down were taught as beginning points using touch as a reinforcer. The final behavior, maintained by naturally occurring reinforcers, was established errorlessly. The study used a control-analysis strategy of behavior change with a changing-criterion design. The intervention resulted in an immediate reduction in hyperactivity and an increase in sitting and lying down for all dogs.
Date: May 2017
Creator: Owens, Chase
Partner: UNT Libraries

A Content Analysis of Medical School Problem-Based Learning Cases

Description: Problem-based learning (PBL) was developed for use in medical education to incorporate more active, learner-centered instruction. Central to problem-based learning is the problem, which in medical education is usually case a case presentation, revealed in stages to allow learners to form and research learning objectives. The purpose of this study was to identify themes present across the PBL cases, including the patient-centeredness of the cases. Content analysis was used to examine 62 PBL cases that comprised the first and second years' core curriculum at a public medical school. The cases included a patient population similar to the local population, but care was more hospital-centric than would be expected from the actual patterns of medical utilization in the United States. Analyzing along two axes of patient-centeredness, the PBL cases demonstrated a good understanding of the patient (knowing the patient), but other qualities such as shared decision making was not as exemplified. Medical educators can use the results to understand elements that contribute to patient-centeredness and apply the analysis framework to evaluate future cases.
Date: May 2017
Creator: Kinkade, Scott Edward
Partner: UNT Libraries

Content and Temporal Analysis of Communications to Predict Task Cohesion in Software Development Global Teams

Description: Virtual teams in industry are increasingly being used to develop software, create products, and accomplish tasks. However, analyzing those collaborations under same-time/different-place conditions is well-known to be difficult. In order to overcome some of these challenges, this research was concerned with the study of collaboration-based, content-based and temporal measures and their ability to predict cohesion within global software development projects. Messages were collected from three software development projects that involved students from two different countries. The similarities and quantities of these interactions were computed and analyzed at individual and group levels. Results of interaction-based metrics showed that the collaboration variables most related to Task Cohesion were Linguistic Style Matching and Information Exchange. The study also found that Information Exchange rate and Reply rate have a significant and positive correlation to Task Cohesion, a factor used to describe participants' engagement in the global software development process. This relation was also found at the Group level. All these results suggest that metrics based on rate can be very useful for predicting cohesion in virtual groups. Similarly, content features based on communication categories were used to improve the identification of Task Cohesion levels. This model showed mixed results, since only Work similarity and Social rate were found to be correlated with Task Cohesion. This result can be explained by how a group's cohesiveness is often associated with fairness and trust, and that these two factors are often achieved by increased social and work communications. Also, at a group-level, all models were found correlated to Task Cohesion, specifically, Similarity+Rate, which suggests that models that include social and work communication categories are also good predictors of team cohesiveness. Finally, temporal interaction similarity measures were calculated to assess their prediction capabilities in a global setting. Results showed a significant negative correlation between the Pacing Rate and ...
Date: May 2017
Creator: Castro Hernandez, Alberto
Partner: UNT Libraries

A Content Originality Analysis of HRD Focused Dissertations and Published Academic Articles using TurnItIn Plagiarism Detection Software

Description: This empirical exploratory study quantitatively analyzed content similarity indices (potential plagiarism) from a corpus consisting of 360 dissertations and 360 published articles. The population was defined using the filtering search criteria human resource development, training and development, organizational development, career development, or HRD. This study described in detail the process of collecting content similarity analysis (CSA) metadata using Turnitin software (www.turnitin.com). This researcher conducted robust descriptive statistics, a Wilcoxon signed-rank statistic between the similarity indices before and after false positives were excluded, and a multinomial logistic regression analysis to predict levels of plagiarism for the dissertations and the published articles. The corpus of dissertations had an adjusted rate of document similarity (potential plagiarism) of M = 9%, (SD = 6%) with 88.1% of the dissertations in the low level of plagiarism, 9.7% in the high and 2.2% in the excessive group. The corpus of published articles had an adjusted rate of document similarity (potential plagiarism) of M = 11%, (SD = 10%) with 79.2% of the published articles in the low level of plagiarism, 12.8% in the high and 8.1% in the excessive group. Most of the difference between the dissertations and published articles were attributed to plagiarism-of-self issues which were absent in the dissertations. Statistics were also conducted which returned a statistically significant justification for employing the investigative process of removing false positives, thereby adjusting the Turnitin results. This study also found two independent variables (reference and word counts) that predicted dissertation membership in the high (.15-.24) and excessive level (.25-1.00) of plagiarism and published article membership in the excessive level (.25-1.00) of plagiarism. I used multinomial logistic regression to establish the optimal prediction model. The multinomial logistic regression results for the dissertations returned a Nagelkerke pseudo R2 of .169 and for the published articles a Nagelkerke pseudo R2 ...
Date: May 2017
Creator: Mayes, Robin James
Partner: UNT Libraries

Creating Discussion: An Auteur Analysis of Films Directed by Adrian Lyne

Description: This thesis examines the various "signature" threads that are present within the "oeuvre" of the Hollywood filmmaker Adrian Lyne. The goal of this thesis is to showcase both how and why Lyne can be thought of as an auteur and to open up his films to new and previously unexplored meanings. Lyne's eight feature films are analyzed in-depth individually and in comparison to one another from a variety of theoretical frameworks and points of focus in each of the body chapters.
Date: May 2017
Creator: Oliver, Stephanie Renee
Partner: UNT Libraries

Culturally Competent Evaluations

Description: Significant growth in the number of English language learners (ELLs) in U.S. schools is anticipated to continue, demanding that educators and evaluators have the skills necessary to distinguishing language difference from disability and provide appropriate services to these students. However, little research exists examining the role of evaluator's cultural competence in evaluating ELLs for special education; furthermore, what does exist shows that many evaluators report low levels of self-efficacy as it relates to assessing ELLs. The first chapter of the dissertation reports on a review of 21 articles conducted to address best practices for evaluating culturally and linguistically diverse (CLD) learners, evaluator self-efficacy, and recommendations for conducting culturally competent assessments and evaluations. The majority of the articles identified in this review focused on recommendations for best practices for conducting evaluations rather than reporting empirical findings related to the topic. Only one study was identified that focused on appropriate training needed by evaluation staff to effectively discriminate between language difference and a disability. Based on the findings of this review, additional research, using a rigorous methodology is needed. Addressing that need, the second chapter reports the results of a study conducted to examine the effectiveness of Project PEAC3E (Preparing Evaluators to Accurately Conduct Culturally Competent Evaluations), a reform-oriented professional development model, using case-based activities designed to increase evaluators' sense of self-efficacy, cultural competence, and the accuracy of evaluator eligibility decisions for English language learners (ELLs). The study found that Project PEAC3E was effective in increasing evaluator self-efficacy.
Date: May 2017
Creator: Chen, Cristina Rodriguez
Partner: UNT Libraries

Design Considerations and Implementation of Portable Mass Spectrometers for Environmental Applications

Description: Portable mass spectrometers provide a unique opportunity to obtain in situ measurements. This minimizes need for sample collection or in laboratory analysis. Membrane Inlet Mass Spectrometry (MIMS) utilizing a semi permeable membrane for selective rapid introduction for analysis. Polydimethylsiloxane membranes have been proven to be robust in selecting for aromatic chemistries. Advances in front end design have allowed for increased sensitivity, rapid sample analysis, and on line measurements. Applications of the membrane inlet technique have been applied to environmental detection of clandestine drug chemistries and pollutants. Emplacement of a mass spectrometer unit in a vehicle has allowed for large areas to be mapped, obtaining a rapid snapshot of the various concentrations and types of environmental pollutants present. Further refinements and miniaturization have allowed for a backpackable system for analysis in remote harsh environments. Inclusion of atmospheric dispersion modeling has yielded an analytical method of approximating upwind source locations, which has law enforcement, military, and environmental applications. The atmospheric dispersion theories have further been applied to an earth based separation, whereby chemical properties are used to approximate atmospheric mobility, and chemistries are further identified has a portable mass spectrometer is traversed closer to a point source.
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Date: May 2017
Creator: Mach, Phillip Michael
Partner: UNT Libraries

Design, Modeling, and Experiment of a Piezoelectric Pressure Sensor based on a Thickness-Shear Mode Crystal Resonator

Description: This thesis presents the design, modeling, and experiment of a novel pressure sensor using a dual-mode AT-cut quartz crystal resonator with beat frequency analysis based temperature compensation technique. The proposed sensor can measure pressure and temperature simultaneously by a single AT-cut quartz resonator. Apart from AT-cut quartz crystal, a newly developed Langasite (LGS) crystal resonator is also considered in the proposed pressure sensor design, since LGS can operate in a higher temperature environment than AT-cut quartz crystal. The pressure sensor is designed using CAD (computer aided design) software and CAE software - COMSOL Multiphysics. Finite element analysis (FEA) of the pressure sensor is performed to analyze the stress- strain of the sensor's mechanical structure. A 3D printing prototype of the sensor is fabricated and the proposed sensing principle is verified using a force-frequency analysis apparatus. Next to the 3D printing model verification, the pressure sensor with stainless steel housing has been fabricated with inbuilt crystal oscillator circuit. The oscillator circuit is used to excite the piezo crystal resonator at its fundamental vibrational mode and give the frequency as an output signal. Based on the FEA and experimental results, it has been concluded that the maximum pressure that the sensor can measure is 45 (psi). The pressure test results performed on the stainless steel product shows a highly linear relationship between the input (pressure) and the output (frequency).
Date: May 2017
Creator: Pham, Thanh Tuong
Partner: UNT Libraries

Design of a Lower Extremity Exoskeleton to Increase Knee ROM during Valgus Bracing for Osteoarthritic Gait

Description: Knee osteoarthritis (KOA) is the primary cause of chronic immobility in populations over the age of 65. It is a joint degenerative disease in which the articular cartilage in the knee joint wears down over time, leading to symptoms of pain, instability, joint stiffness, and misalignment of the lower extremities. Without intervention, these symptoms gradually worsen over time, decreasing the overall knee range of motion (ROM) and ability to walk. Current clinical interventions include offloading braces, which mechanically realign the lower extremities to alleviate the pain experienced in the medial compartment of the knee joint. Though these braces have proven effective in pain management, studies have shown a significant decrease in knee ROM while using the brace. Concurrently, development of active exoskeletons for rehabilitative gait has increased within recent years in efforts to provide patients with a more effective intervention for dealing with KOA. Though some developed exoskeletons are promising in their efficacy of fostering gait therapy, these devices are heavy, tethered, difficult to control, unavailable to patients, or costly due to the number of complicated components used to manufacture the device. However, the idea that an active component can improve gait therapy for patients motivates this study. This study proposes the design of an adjustable lower extremity exoskeleton which features a single linear actuator adapted onto a commercially available offloading brace. This design hopes to provide patients with pain alleviation from the brace, while also actively driving the knee through flexion and extension. The design and execution of this exoskeleton was accomplished by 3D computer simulation, 3D CAD modeling, and rapid prototyping techniques. The exoskeleton features 3D printed, ABS plastic struts and supports to achieve successful adaptation of the linear actuator to the brace and an electromechanical system with a rechargeable operating capacity of 7 hours. Design validation was ...
Date: May 2017
Creator: Cao, Jennifer M
Partner: UNT Libraries

Design Principle on Carbon Nanomaterials Electrocatalysts for Energy Storage and Conversion

Description: We are facing an energy crisis because of the limitation of the fossil fuel and the pollution caused by burning it. Clean energy technologies, such as fuel cells and metal-air batteries, are studied extensively because of this high efficiency and less pollution. Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential in the process of energy storage and conversion, and noble metals (e.g. Pt) are needed to catalyze the critical chemical reactions in these devices. Functionalized carbon nanomaterials such as heteroatom-doped and molecule-adsorbed graphene can be used as metal-free catalysts to replace the expensive and scarce platinum-based catalysts for the energy storage and conversion. Traditionally, experimental studies on the catalytic performance of carbon nanomaterials have been conducted extensively, however, there is a lack of computational studies to guide the experiments for rapid search for the best catalysts. In addition, theoretical mechanism and the rational design principle towards ORR and OER also need to be fully understood. In this dissertation, density functional theory calculations are performed to calculate the thermodynamic and electrochemical properties of heteroatom-doped graphene and molecule-adsorbed graphene for ORR and OER. Gibb's free energy, overpotential, charge transfer and edge effect are evaluated. The charge transfer analysis show the positive charges on the graphene surface caused by the heteroatom, hetero-edges and the adsorbed organic molecules play an essential role in improving the electrochemical properties of the carbon nanomaterials. Based on the calculations, design principles are introduced to rationally design and predict the electrochemical properties of doped graphene and molecule-adsorbed graphene as metal-free catalysts for ORR and OER. An intrinsic descriptor is discovered for the first time, which can be used as a materials parameter for rational design of the metal-free catalysts with carbon nanomaterials for energy storage and conversion. The success of the design principle provides a better ...
Date: May 2017
Creator: Zhao, Zhenghang
Partner: UNT Libraries

Determinants of Corporate Governance Choices: Evidence from Listed Foreign Firms on U.S. Stock Exchanges

Description: This study analyzes corporate governance practices of foreign (non-U.S.) issuers listed on the New York Stock Exchange (NYSE) and Nasdaq. Specifically, I examine the extent to which these foreign issuers voluntarily comply with U.S. stock exchange corporate governance requirements applicable to domestic issuers. My sample consists of 201 foreign companies primarily domiciled in Brazil, China, Israel, and the United Kingdom. I find that 151 (75 per cent) of the sample firms do not elect to comply with any of the U.S. corporate governance requirements. Logistic regression analysis generally supports the hypotheses that conformance with U.S. GAAP and percentage of managerial ownership are positively associated, and that percentage ownership by major shareholders is negatively associated with foreign firms electing to comply with U.S. corporate governance rules. This evidence is relevant for regulators and investors.
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Date: May 2017
Creator: Attachot, Weerapat
Partner: UNT Libraries

Determining Whether and When People Participate in the Events They Tweet About

Description: This work describes an approach to determine whether people participate in the events they tweet about. Specifically, we determine whether people are participants in events with respect to the tweet timestamp. We target all events expressed by verbs in tweets, including past, present and events that may occur in future. We define event participant as people directly involved in an event regardless of whether they are the agent, recipient or play another role. We present an annotation effort, guidelines and quality analysis with 1,096 event mentions. We discuss the label distributions and event behavior in the annotated corpus. We also explain several features used and a standard supervised machine learning approach to automatically determine if and when the author is a participant of the event in the tweet. We discuss trends in the results obtained and devise important conclusions.
Date: May 2017
Creator: Sanagavarapu, Krishna Chaitanya
Partner: UNT Libraries

Development of an Outcome Measure for Use in Psychology Training Clinics

Description: The ability to monitor client change in psychotherapy over time is vital to quality assurance in service delivery as well as the continuing improvement of psychotherapy research. Unfortunately, there is not currently a comprehensive, affordable, and easily utilized outcome measure for psychotherapy specifically normed and standardized for use in psychology training clinics. The current study took the first steps in creating such an outcome measure. Following development of an item bank, factor analysis and item-response theory analyses were applied to data gathered from a stratified sample of university (n = 101) and community (n = 261) participants. The factor structure did not support a phase model conceptualization, but did reveal a structure consistent with the theoretical framework of the research domain criteria (RDoC). Suggestions for next steps in the measure development process are provided and implications discussed.
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Date: May 2017
Creator: Davis, Elizabeth C.
Partner: UNT Libraries

Development of von Willebrand Factor Zebrafish Mutant Using CRISPR/Cas9 Mediated Genome Editing

Description: von Willebrand factor (VWF) protein acts in the intrinsic coagulation pathway by stabilizing FVIII from proteolytic clearance and at the site of injury, by promoting the adhesion and aggregation of platelets to the exposed subendothelial wall. von Willebrand disease (VWD) results from quantitative and qualitative deficiencies in VWF protein. The variability expressivity in phenotype presentations is in partly caused by the action of modifier genes. Zebrafish has been used as hemostasis animal model. However, it has not been used to evaluate VWD. Here, we report the development of a heterozygote VWF mutant zebrafish using the genome editing CRISPR/Cas9 system to screen for modifier genes involved in VWD. We designed CRISPR oligonucleotides and inserted them into pT7-gRNa plasmid. We then prepared VWF gRNA along with the endonuclease Cas9 RNA from Cas9 plasmid. We injected these two RNAs into 1-4 cell-stage zebrafish embryos and induced a mutation in VWF exon 29 of the zebrafish with a mutagenesis rate of 16.6% (3/18 adult fish). Also, we observed a germline transmission with an efficiency rate of 5.5% (1/18 adult fish). We obtained a deletion in exon 29 which should result in truncated VWF protein.
Date: May 2017
Creator: Toffessi Tcheuyap, Vanina
Partner: UNT Libraries

Disease Tissue Imaging and Single Cell Analysis with Mass Spectrometry

Description: Cells have been found to have an inherent heterogeneity that has led to an increase in the development of single-cell analysis methods to characterize the extent of heterogeneity that can be found in seemingly identical cells. With an understanding of normal cellular variability, the identification of disease induced cellular changes, known as biomarkers, may become more apparent and readily detectable. Biomarker discovery in single-cells is challenging and needs to focus on molecules that are abundant in cells. Lipids are widely abundant in cells and play active roles in cellular signaling, energy metabolism, and are the main component of cellular membranes. The regulation of lipid metabolism is often disrupted or lost during disease progression, especially in cancer, making them ideal candidates as biomarkers. Challenges exist in the analysis of lipids beyond those of single-cell analysis. Lipid extraction solvents must be compatible with the lipid or lipids of interest. Many lipids are isobaric making mass spectrometry analysis difficult without separations. Single-cell extractions using nanomanipulation coupled to mass spectrometry has shown to be an excellent method for lipid analysis of tissues and cell cultures. Extraction solvents are tunable for specific lipid classes, nanomanipulation prevents damage to neighboring cells, and lipid separations are possible through phase dispersion. The most important aspect of single-cell analysis is that it uncovers the extent of cellular heterogeneity that exists among cellular populations that remains undetected during averaged sampling.
Date: May 2017
Creator: Hamilton, Jason S
Partner: UNT Libraries

"Don't Frack with Denton"

Description: Don't Frack With Denton chronicles the ground-breaking movement to ban hydraulic fracturing in the city of Denton, Texas by combining observational location shooting with extensive sit-down interviews and carefully negotiated subject-filmmaker relationships to create a safe and comfortable space for thoughtful reflection and criticism of a complex social movement who's activities span several years and many individuals. The result is a long-form documentary that is unapologetically in solidarity with this movement's goals while simultaneously maintaining enough editorial independence and critical distance to allow the activists themselves to honestly evaluate their decision-making, tactics and interpersonal relationships in ways that will provide insight and instruction to similar movements around the country and the world.
Date: May 2017
Creator: Graham, Garrett
Partner: UNT Libraries

EEG Signal Analysis in Decision Making

Description: Decision making can be a complicated process involving perception of the present situation, past experience and knowledge necessary to foresee a better future. This cognitive process is one of the essential human ability that is required from everyday walk of life to making major life choices. Although it may seem ambiguous to translate such a primitive process into quantifiable science, the goal of this thesis is to break it down to signal processing and quantifying the thought process with prominence of EEG signal power variance. This paper will discuss the cognitive science, the signal processing of brain signals and how brain activity can be quantifiable through data analysis. An experiment is analyzed in this thesis to provide evidence that theta frequency band activity is associated with stress and stress is negatively correlated with concentration and problem solving, therefore hindering decision making skill. From the results of the experiment, it is seen that theta is negatively correlated to delta and beta frequency band activity, thus establishing the fact that stress affects internal focus while carrying out a task.
Date: May 2017
Creator: Salma, Nabila
Partner: UNT Libraries

The Effect of a Change Facilitator on Project-Based Learning Curriculum and Design

Description: This study sought to understand concerns and levels of use of a group of teachers in the process of developing a project-based learning (PBL) program, and the effect of a change facilitator on these processes. The research was guided by the following research questions: One, what are the concerns of teachers regarding the planning of a PBL curriculum? Two, what are the levels of use of teachers in the process of planning the PBL curriculum? Three, how does a change facilitator affect the process of change in the planning of a PBL curriculum? The population of this study consisted of seven subject area high school teachers and one district level administrative staff member. This study used the concerns-based adoption model (CBAM) to study the PBL innovation. CBAM is a conceptual framework that describes, explains, and predicts teachers' concerns and behaviors throughout the change process in education. In this study, the teachers progressed through the levels of use on a timeline at a rate that was much more rapid that what is typical for implementation of an innovation in an educational setting. This rapid progression was the function of the teacher population studied and the change facilitator that led the PBL curriculum design process. With the leadership of the change facilitator, the goals of the PBL curriculum innovation were realized, and the team created a PBL curriculum with multidisciplinary PBL products that could be implemented after the development phase.
Date: May 2017
Creator: Fry, Jana
Partner: UNT Libraries

Effectiveness of Fillers for Corrosion Protection of AISI-SAE 1018 Steel in Sea Salt Solution

Description: Corrosion represents the single most frequent cause for product replacement or loss of product functionality with a 5% coat to the industrial revenue generation of any country in this dissertation the efficacy of using filled coatings as a protection coating are investigated. Fillers disrupt the polymer-substrate coating interfacial area and lead to poor adhesion. Conflicting benefits of increasing surface hardness and corrosion with long term durability through loss of adhesion to the substrate are investigated. The effects of filler type, filler concentration and exposure to harsh environments such as supercritical carbon dioxide on salt water corrosion are systematically investigated. The constants maintained in the design of experiments were the substrate, AISI-SAE 1018 steel substrate, and the corrosive fluid synthetic sea salt solution (4.2 wt%) and the polymer, Bismaleimide (BMI). Adhesion strength through pull-off, lap shear and shear peel tests were determined. Corrosion using Tafel plots and electrochemical impedance spectroscopy was conducted. Vickers hardness was used to determine mechanical strength of the coatings. SEM and optical microscopy were used to examine dispersion and coating integrity. A comparison of fillers such as alumina, silica, hexagonal boron nitride, and organophilic montmorillonite clay (OMMT) at different concentrations revealed OMMT to be most effective with the least decrease in adhesion from filler-substrate contact. Subsequently examining filler concentration, a 3 wt% OMMT was found to be most effective. A comparison of unmodified and modified BMI with 3 wt% OMMT exposed and not exposed to supercritical carbon dioxide showed that the BMI provided better corrosion protection; however, OMMT provided better wear, shear, and hardness performance.
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Date: May 2017
Creator: Al-Shenawa, Amaal Abdallah Ali
Partner: UNT Libraries

The Effectiveness of Hybrid Problem-Based Learning versus Manual-Based Learning in the Microbiology Laboratory

Description: Promising results from the use of problem-based learning (PBL) as a teaching method in medical programs have encouraged many institutions to incorporate PBL into their curricula. This study investigates how applying hybrid-PBL (H-PBL) in a microbiology laboratory impacts students' higher-order thinking as compared to applying a lecture-based pedagogy. The experimental design compared the learning outcomes of two groups of students: the control group and the H-PBL group, for whom PBL cases comprised 30% of the curriculum. Both groups were taught basic skills for the microbiology lab by the same instructor. Using the traditional teaching style for the control group, the instructor offered each student what they needed for their experiments. The H-PBL group practiced experimental design, data analysis, theory proposal, and created research questions by using six study cases that were closely linked to the area of study. The outcome was measured using a pre- and post- assessment consisting of 24 questions that was designed by following Bloom's taxonomy of learning levels. A one-way ANOVA was used to analyze the data. The results showed that for the first three levels of Bloom's taxonomy— knowledge, comprehension, and application—there were no statistically significant differences between the H-PBL and control group gain scores as determined by a one-way ANOVA. For the knowledge level, f (1, 78) = .232, and p = .632; for the comprehension level, f (1, 78) = .004, and p = .951; and for the application level f (1, 78) =. 028, and p =.863. On the other hand, the gain scores for the three higher levels—analysis, evaluation, and creativity—improved for the H-PBL group. The analysis level showed statistically significant differences, with f (1, 78) = 4.012, and p = .049. Also, there were statistically significant differences in students' performance at the evaluation level, with f (1, 78) = 11.495, ...
Date: May 2017
Creator: Alharbi, Najwa
Partner: UNT Libraries

The Effects of Air Pollution on the Intestinal Microbiota: A Novel Approach to Assess How Gut Microbe Interactions with the Environment Affect Human Health

Description: This thesis investigates how air pollution, both natural and anthropogenic, affects changes in the proximal small intestine and ileum microbiota profile, as well as intestinal barrier integrity, histological changes, and inflammation. APO-E KO mice on a high fat diet were randomly selected to be exposed by whole body inhalation to either wood smoke (WS) or mixed vehicular exhaust (MVE), with filtered air (FA) acting as the control. Intestinal integrity and histology were assessed by observing expression of well- known structural components tight junction proteins (TJPs), matrix metallopeptidase-9 (MMP-9), and gel-forming mucin (MUC2), as well known inflammatory related factors: TNF-α, IL-1β, and toll-like receptor (TLR)-4. Bacterial profiling was done using DNA analysis of microbiota within the ileum, utilizing 16S metagenomics sequencing (Illumina miSeq) technique. Overall results of this experiment suggest that air pollution, both anthropogenic and natural, cause a breach in the intestinal barrier with an increase in inflammatory factors and a decrease in beneficial bacteria. This evidence suggests the possibility of air pollution being a potential causative agent of intestinal disease as well as a possible contributing mechanism for induction of systemic inflammation.
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Date: May 2017
Creator: Fitch, Megan
Partner: UNT Libraries