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 Decade: 2010-2019
Effects of Tasks on Information-Seeking Behavior in a Police Work Environment in the Context of Criminal Intelligence

Effects of Tasks on Information-Seeking Behavior in a Police Work Environment in the Context of Criminal Intelligence

Date: May 2010
Creator: Tatil, Serkan
Description: Although dominant effects of tasks on individuals' information-seeking behavior is accepted by many scholars, a limited number of studies has been conducted to reveal the nature of the relationship between tasks and information-seeking behavior. In their studies, some earlier researchers categorized tasks according to their complexity while others did the same according to the specifications of tasks. Two of the groundbreaking researchers in this area are Katriina Byström and Kalervo Järvelin who contributed to the understanding of the relationship between task complexity and information-seeking behavior. However, their findings also need empirical support for theory growth. In response to this need, this study attempts to test Byström and Järvelin's findings through a research using different research methods and applied in a police work environment. Other than providing empirical support for theory growth, this research is also expected to contribute to the understudied area of police information-seeking behavior. Both qualitative and quantitative data were collected from the participants who came from traffic, homicide, and anti-terrorism divisions of Ankara, Eskisehir, and Kirikkale Police Departments in Turkey. The participants identified terrorism cases as the most complex cases to solve, followed by homicide and traffic accident cases. Differences in the information-seeking behavior of three groups ...
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The Effects of Textual Fluency on the Rate of Acquisition and Application of Intraverbal Relations

The Effects of Textual Fluency on the Rate of Acquisition and Application of Intraverbal Relations

Date: May 2012
Creator: Shrontz, Rachael E.
Description: Intraverbal behavior governs core elements of academic and intellectual behavior. These intraverbal relations can be explicitly taught when an individual is prompted to provide an appropriate response with pictures, text, or other stimuli following a verbal stimulus. It is possible that a focus on fluency of the target repertoires may lead to more conclusive data. the current study assessed the effects of precision teaching based instruction for component textual repertoires on the acquisition of intraverbal relations. Specifically, this study compared the effectiveness of two textual prompting procedures (with and without fluency-based instruction) on the acquisition and application of intraverbal relations using time-delay and a carefully controlled set of intraverbal stimuli. Results indicate that the use of textual prompts and an errorless time-delay transfer of stimulus control procedure were effective strategies for teaching intraverbal responses regardless of the inclusion of fluency-based instruction.
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Effects of the Texas Principal Excellence Program on Texas Principal Leadership Behavior and School Outcomes

Effects of the Texas Principal Excellence Program on Texas Principal Leadership Behavior and School Outcomes

Date: May 2011
Creator: Fouche, Todd P.
Description: The purpose of this study was to examine the leadership and school outcome effects of the Texas Principal Improvement program; which authorized the School Leadership Pilot Program under Texas Education Code 11.203. The specific research questions were: What effects did participating in the Texas Principal Excellence Program in 2009-2010 have on participants and their schools? What changes in participants' self-reported and peer-observed leader behaviors occurred between the initial assessment at the onset of the program and the final assessment once the program was completed? What changes were experienced in school's passing rate on mathematics and reading TAKS in schools having the same principal for the two years in 2008-2009 (pre-participation) and 2009-2010 (post participation). The research used TxPEP participating principals who agreed to take part in the study. Principals and a selected group of people who worked with them completed a 360-degree leadership feedback instrument addressing nine leadership competencies at the beginning and end of the program. Paired samples t-tests were used to determine if changes from pre-participation to post-participation were statistically significant. When a statistically significant difference was found, effect size and confidence intervals were calculated to place the data in context. Multiple regression and propensity score matching were ...
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The Effects of the Texas Reading First Response to Intervention Program on Student Achievement and Campus Special Education Rates

The Effects of the Texas Reading First Response to Intervention Program on Student Achievement and Campus Special Education Rates

Date: August 2013
Creator: Batts, Troy D.
Description: The purpose of this study was to examine special education populations, special education reading achievement, and regular education reading achievement in relation to the implementation of the Reading First three-tiered model as a response to Intervention platform. The population for this study focused on rural schools with Grades K-3 in attendance. Schools participated in the reading first grant period of the 2003-2009 school years. Forty-seven Texas Reading First schools were compared to 47 campuses having similar populations, socioeconomic makeups, and grade structures. This study utilized quantitative research measures to evaluate the level of special education populations on Reading First campuses using a response to intervention model. Quantitative measures were also used to evaluate those same campuses achievement rates of both special education and regular education students on the Texas Assessment of Knowledge and Skills reading tests. The study's outcome data showed little to no statistic significance for the three research questions. However, the inferential statistics showed a decrease in the special education population of the Reading First schools. Inferential statistics also indicated both the special education and the regular education students showed growth on the Texas Assessment of Knowledge and Skills reading tests. The use of a response to intervention ...
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Effects of the Why Try Social Skills Program on Students with Emotional and Behavioral Disorders at an Alternative Campus

Effects of the Why Try Social Skills Program on Students with Emotional and Behavioral Disorders at an Alternative Campus

Date: December 2010
Creator: Wilhite, Shannon
Description: Approximately 20% of students with emotional and behavioral disorders (E/BD) are sent to an alternative campus for their lack of social competence. Social skills training (SST) is an evidence-based intervention to help increase social competence for students with E/BD, but there is limited research that addresses SST for students with E/BD at alternative campuses. A mixed-methods design was utilized to examine SST at an alternative campus for students with E/BD. Pre-intervention data were collected for students' attendance, grades, office disciplinary referrals, and behavioral rating scales, after which, the Why Try SST program was implemented. Following the intervention, the same type of data were collected. Nonparametric statistics guided the quantitative analysis, because of the small population being studied. Differences from pre- to post-intervention were examined. Triangulation methods drove the qualitative data collection and analysis through observations, student interviews, and teacher interviews. Students exhibited significant differences from pre- to post-intervention in the number of office disciplinary referrals and several areas on the behavioral rating scales. Important insight into motivation and perceptions was gained through the observations and interviews.
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The Effects of Training History on Retention and Reacquisition of Stimulus Control

The Effects of Training History on Retention and Reacquisition of Stimulus Control

Date: August 2013
Creator: Tucker, Kathryn Lynn
Description: The purpose of this experiment was to study the effects of training history on retention and re-acquisition of stimulus control of previously learned behaviors. In Phase I, two pairs of behaviors were alternately trained. Circle and touch behaviors were trained concurrently until two consecutive errorless sessions were run. Spin and down behaviors were trained together in the same manner. Probe sessions, in which all four cues were presented, were conducted each time a pair of behaviors reached this criterion. Training of one pair did not occur until the other pair had reached criterion and probe sessions were run. Despite achieving the designated criterion during training, stimulus control changed during probes. During probe sessions, errors increased under the cues that were not currently being trained. In most cases, the type of errors emitted for each cue was the same as the behavior that was trained concurrently. The number of training sessions required to reach criterion accuracy was high during the first set of sessions and decreased over the course of the experiment. In Phase II, spin and circle behaviors were trained concurrently. The number of sessions required to reach stimulus control criteria remained low, and the number of errors emitted under ...
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Effects of UE Speed on MIMO Channel Capacity in LTE

Effects of UE Speed on MIMO Channel Capacity in LTE

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Date: August 2016
Creator: Shukla, Rahul
Description: With the introduction of 4G LTE, multiple new technologies were introduced. MIMO is one of the important technologies introduced with fourth generation. The main MIMO modes used in LTE are open loop and closed loop spatial multiplexing modes. This thesis develops an algorithm to calculate the threshold values of UE speed and SNR that is required to implement a switching algorithm which can switch between different MIMO modes for a UE based on the speed and channel conditions (CSI). Specifically, this thesis provides the values of UE speed and SNR at which we can get better results by switching between open loop and closed loop MIMO modes and then be scheduled in sub-channels accordingly. Thus, the results can be used effectively to get better channel capacity with less ISI. The main objectives of this thesis are: to determine the type of MIMO mode suitable for a UE with certain speed, to determine the effects of SNR on selection of MIMO modes, and to design and implement a scheduling algorithm to enhance channel capacity.
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Effects of Using Logic and Spatial Cybergames to Improve Student Success Rates in Lower-Division Chemistry Courses

Effects of Using Logic and Spatial Cybergames to Improve Student Success Rates in Lower-Division Chemistry Courses

Date: May 2011
Creator: Manrique, Carissa Janice
Description: A study was conducted to investigate the relationships between cybergaming treatment groups and the control group (N = 99: ncontrol = 8; nlogic = 29; nspatial = 30; ncombination = 32) with success in the organic chemistry I course as measured by achievement over a 10-week period. The treatment groups included logic training, spatial training, and combination logic-spatial training. Students' ability was measured by pre/post exams using the Group Assessment of Logical Thinking (GALT) to measure logic ability, Purdue Visualizations of Rotations (ROT) test to measure spatial skills, and the General-Organic-Biochemistry (GOB) Exam to measure content attainment. Finally, students' responses about participation in this experience were evaluated using open- and closed-ended questions on a self-developed survey. A second study was conducted to evaluate the relationship between the cybergaming treatment and control groups (N = 88: nexperimental = 27; ncontrol = 61) with success in the general chemistry I course as measured by achievement and final course averages and grades. The cybergaming treatment group underwent intensive combination logic-spatial training for 10 weeks. Students' progress was measured using three pre/post instruments: Group Assessment of Logical Thinking (GALT) measured logic ability, Purdue Visualizations of Rotations (ROT) Test measured spatial skills, and the California ...
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Effects of Vegetation Structure and Canopy Exposure on Small-scale Variation in Atmospheric Deposition Inputs to a Mixed Conifer Forest in California

Effects of Vegetation Structure and Canopy Exposure on Small-scale Variation in Atmospheric Deposition Inputs to a Mixed Conifer Forest in California

Date: May 2014
Creator: Griffith, Kereen
Description: Data on rates of atmospheric deposition is limited in many montane ecosystems, where high spatial variability in meteorological, topographic, and vegetation factors contributes to elevated atmospheric inputs and to the creation of deposition hotspots. Addressing the ecological consequences of increasing deposition in these areas will require a better understanding of surface controls influencing atmospheric deposition rates at both large and small-scales. The overarching objective of this thesis research was to understand the influence of vegetation structure and canopy exposure on small-scale patterns of atmospheric sulfate, nitrate, and chloride deposition inputs to a conifer forest in the Santa Cruz Mountains, California. Throughfall ion fluxes (i.e., ions delivered in water that pass from the forest canopy to the forest floor), bulk deposition (i.e., primarily wet deposition), and rainfall data were collected during the rainy period from October 2012 to May 2013. Throughfall SO42-, Cl-, and NO3- fluxes were measured beneath eight clusters of Douglas fir (Pseudotsuga menziesii) trees (three trees per cluster) differing in tree size (i.e., diameter at breast height; DBH) and canopy exposure. In each cluster, a throughfall collector was placed 1-meter from the bole of an individual tree, for a total of 24 individual collectors. The position of each ...
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Efficacy in Texas Charter Schools Compared to Traditional Public Schools

Efficacy in Texas Charter Schools Compared to Traditional Public Schools

Date: August 2015
Creator: Keller, Karlyn
Description: The need to spur innovation and improve student performance initiated the formation of, under different legislative acts, charter schools that include variations of traditional public schools. With the enthusiasm and level of investment going into the formation of charter schools, it is necessary to explore whether these schools have achieved their objectives. This study explored whether Texas open enrollment charter schools perform bettered compared to Texas public schools. The study applied a causal comparative quantitative research design. School data on graduation and dropout rates, college preparation, attendance rates, and overall performance were analyzed quantitatively. Student achievement data available for statistical analysis includes student performance on the Texas Assessment of Knowledge and Skills (TAKS) state assessment from 2007 to 2011. Data analysis for race, special programs, at risk, economically disadvantaged, and limited English proficiency was incorporated. Descriptive statistics and analysis of variance techniques were included in the data analysis. The analysis extended to post hoc tests to determine variables that caused variation. The study found Texas open-enrollment charter schools had more African American students but fewer Whites compared to public schools. Students in public schools performed better than those in charter schools, and Whites yielded the best performance. Charter schools had ...
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The Efficacy of the Chickasaw Nation Early Care and Education Programs

The Efficacy of the Chickasaw Nation Early Care and Education Programs

Date: May 2014
Creator: Blackmon, Lisa
Description: The purposes of this research were to explore the effectiveness of the Chickasaw Nation early care and education program in promoting school readiness while infusing tribally relevant values in children from birth through age five; engaging parents in all aspects of their children’s learning; and supporting children and families through the transitioning to kindergarten. The study used qualitative methods to examine the experiences and perceptions of ten parents, ten teachers, and five administrators within Chickasaw Nation’s early care and education system regarding the four basic areas of school readiness, parent engagement, transition, and culturally relevant pedagogy. Four primary themes emerged from the semi-structured interviews: 1) socialization, school readiness, and transition, 2) learning, curriculum, and assessment, 3) the role of parents, and 4) cultural integrity. Data were collected through semi-structured interviews, transcribed, and analyzed based on four research questions. Findings indicated parents, teachers, and administrators were satisfied that the program was successful with assisting children in making progress toward achieving developmental and school readiness goals and that the children were physically, socially, emotionally, and cognitively prepared to enter kindergarten. The program provided activities to encourage and promote parental involvement; however, parents did not indicate active involvement or participation in the activities. ...
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Efficiency of Nitrate and Phosphorus Removal in a Working Rain Garden

Efficiency of Nitrate and Phosphorus Removal in a Working Rain Garden

Date: August 2015
Creator: Strong, Patrick
Description: Rain gardens are low impact developments designed to mitigate a suite of issues associated with urban stormwater runoff. The site for this study was a Denton City rain garden at the Denton Waste Water Treatment Plant. Nitrogen and phosphorus removal was examined in light of two overflow events comprised of partially treated wastewater from an upslope anaerobic digester pond. Nitrate removal efficiency was examined across differing dry spell intervals of 5, 8, and 12 d, displaying a moderate negative correlation (r2 = 0.59). Continued phosphorus removal capacity was assessed, showing phosphorus removal in cases where P was in excess of 0.8 mg/L, reflecting an equilibrium phosphorus concentration. A high expanded shale component in the soil media (25%) was likely a factor in the continued removal of phosphorus. Overall the rain garden proved to be a large source of nitrate (+425%) and total nitrogen (+61%) by mass. The study showed that while the rain garden intercepted a large volume of partially treated wastewater during the overflow events, preventing it from reaching a nearby creek, the mitigation of an acute event has extended to a chronic one as nitrogen is gradually processed and flushed from the system as nitrate.
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Eight-Year Course of Cognitive Functioning in Bipolar Disorder with Psychotic Features

Eight-Year Course of Cognitive Functioning in Bipolar Disorder with Psychotic Features

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Date: August 2016
Creator: Bain, Kathleen Marie
Description: The purpose of the current study was to examine neuropsychological functioning in patients with bipolar disorder (BD) with psychotic features. Data from a large, epidemiological study of patients with first-episode psychosis was used to examine verbal learning and working memory 10 years after onset of psychosis in patients with BD relative to patients with schizophrenia (SZ) and patients with psychotic major depressive disorder (MDD). Cross-sectional comparisons of verbal learning and working memory at the 10-year follow-up mirrored findings of relative performance at the 2-year follow-up (Mojtabai, 2000), as patients with SZ performed significantly worse than patients with psychotic affective disorders. When FEP patients' cognitive performance was examined longitudinally, all groups showed non-significant decline over time, with no significant diagnostic group differences after accounting for current symptoms. More frequent hospitalizations and longer treatment with antipsychotics were associated with poorer performance on cognitive testing 10 years after illness onset, but these associations disappeared when controlling baseline cognitive performance. Within the BD sample, current positive and negative psychotic symptoms were associated with poorer performance on cognitive testing. After controlling for baseline cognitive performance, markers of clinical course were unrelated to cognitive performance, consistent with existing literature on longitudinal cognitive functioning in patients with ...
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Eighth Grade Science Teacher Quality Variables and Student Achievement

Eighth Grade Science Teacher Quality Variables and Student Achievement

Date: December 2010
Creator: Harp, Amy
Description: While No Child Left Behind ushered in the age of the "highly qualified" teacher, accountability focus has been shifted to the "highly effective" teacher, defined as teacher impact on student achievement. The Science Texas Assessment of Knowledge and Skills (TAKS) is used to judge the adequate yearly progress of students in Texas public schools. Therefore, the purpose of this study was to examine the relationship of teacher factors (i.e., ethnicity, gender, teaching experience, university selectivity, certification route, National Center for Education Statistics Locale/Code, number of science content and pedagogical course semester credit hours, grade point average for science content and pedagogical coursework) on student achievement using the eighth grade Science TAKS. The primary dependent variables were students' five objective scores and their overall scores on the eighth grade Science TAKS examination. The sample was 44 eighth grade science teachers and 4,119 students in Texas public schools. Multiple linear regression models enabled examinations of the relationships between teacher quality variables and student achievement. No significant relationships between the variables were found. Small effect sizes for the beta weights and structure coefficients occurred between teachers' science credit hours and TAKS objectives to explain 20% of the variance for TAKS Living Systems and ...
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El ékfrasis en la Poesía De Manual Machado

El ékfrasis en la Poesía De Manual Machado

Date: May 2011
Creator: Carrillo, Yolanda
Description: Manuel Machado is known as one of the most innovative Spanish modernist poets of the twentieth century. Despite his recognition as a literary figure in Spain, the mimetic descriptions in Machado's poetics are interpreted as mere innovations in Spanish poetry. Those mimetic descriptions are examples of ekphrasis in Spanish literature. Ekphrasis is both a literary and representational art. The mimetic dimension in Machado's poetry is ignored or misinterpreted by the critics of his poetics. This study written in Spanish investigates the use of ekphrasis in terms of Machado's poetic style. An analysis of Manuel Machado's ekphrastic poems will determine: ekphrastic poetry is a representational art; how visual and acoustic aspects of Machado's poems create enargeia; and the manifestation of ekphrasis in Spanish verse. In using Machado's poems, this project will contribute to future explorations of ekphrasis in Spanish literature.
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Electoral Rules, Political Parties, and Peace Duration in Post-conflict States

Electoral Rules, Political Parties, and Peace Duration in Post-conflict States

Date: December 2014
Creator: Kisin, Tatyana Tuba Kelman
Description: This dissertation examines the following research question: Which types of electoral rules chosen in post-conflict states best promote peace? And are those effects conditional upon other factors? I argue that the effects are conditional upon the types of political parties that exist in the post-conflict environment. Although this explanation is contrary to scholars that speak of political parties as products of the electoral system, political parties often predate the choice of electoral system. Especially in post-conflict states, political parties play an important role in the negotiation process and hence in the design of the electoral rules. I argue that the effects of electoral rules on peace duration are mitigated by the degree to which a party system is broad (nonexclusive) or narrow (exclusive). I develop a theoretical model that led to three hypotheses focusing on the independent role that political parties play in mitigating the effects of electoral rules on peace duration. To test these hypotheses, I use the Cox proportional hazard model on 57 post-conflict states from 1990 to 2009 and had competitive elections. The empirical results show support for the main argument of this study. First, the findings show that electoral rules alone do not increase or decrease ...
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Electoral System Effects On Anti-muslim Sentiments In Western Europe

Electoral System Effects On Anti-muslim Sentiments In Western Europe

Date: December 2011
Creator: Saleemi, Asmara
Description: The purpose of this thesis is to answer the question, why is there a variation in anti-Muslim sentiments across Western Europe? There is existing literature on individual and country-level variable s to explain why prejudice exists, but this research examines the impact of political institutions on anti-Muslim sentiments. Based on new institutionalism theory, electoral systems can shape public attitudes by providing far-right parties a platform to put their concerns on the agenda, and these parties promote anti-Muslim popular sentiments. The results of this analysis support this argument in that the larger the average district magnitude in a country, the greater the anti-Muslim sentiments. The findings also show that an increase in far-right party vote-share also covaries with an increase in anti-Muslim sentiments.
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Electrical and Structure Properties of High-κ Barium Tantalite and Aluminum Oxide Interface with Zinc Oxide for Applications in Transparent Thin Film Transistors

Electrical and Structure Properties of High-κ Barium Tantalite and Aluminum Oxide Interface with Zinc Oxide for Applications in Transparent Thin Film Transistors

Date: August 2011
Creator: Kuo, Fang-Ling
Description: ZnO has generated interest for flexible electronics/optoelectronic applications including transparent thin film transistors (TFTs). For this application, low temperature processes that simultaneously yield good electrical conductivity and optical transparency and that are compatible with flexible substrates such as plastic, are of paramount significance. Further, gate oxides are a critical component of TFTs, and must exhibit low leakage currents and self-healing breakdown in order to ensure optimal TFTs switching performance and reliability. Thus, the objective of this work was twofold: (1) develop an understanding of the processing-structure-property relationships of ZnO and high-κ BaTa2O6 and Al2O3 (2) understand the electronic defect structure of BaTa2O6 /ZnO and Al2O3/ZnO interfaces and develop insight to how such interfaces may impact the switching characteristics (speed and switching power) of TFTs featuring these materials. Of the ZnO films grown by atomic layer deposition (ALD), pulsed laser deposition (PLD) and magnetron sputtering at 100-200 °C, the latter method exhibited the best combination of n-type electrical conductivity and optical transparency. These determinations were made using a combination of photoluminescence, photoluminescence excitation, absorption edge and Hall measurements. Metal-insulator-semiconductor devices were then fabricated with sputtered ZnO and high-κ BaTa2O6 and Al2O3 and the interfaces of high-κ BaTa2O6 and Al2O3 with ZnO ...
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Electrical Conduction Mechanisms in the Disordered Material System P-type Hydrogenated Amorphous Silicon

Electrical Conduction Mechanisms in the Disordered Material System P-type Hydrogenated Amorphous Silicon

Date: December 2014
Creator: Shrestha, Kiran (Engineer)
Description: The electrical and optical properties of boron doped hydrogenated amorphous silicon thin films (a-Si) were investigated to determine the effect of boron and hydrogen incorporation on carrier transport. The a-Si thin films were grown by plasma enhanced chemical vapor deposition (PECVD) at various boron concentrations, hydrogen dilutions, and at differing growth temperatures. The temperature dependent conductivity generally follows the hopping conduction model. Above a critical temperature, the dominant conduction mechanism is Mott variable range hopping conductivity (M-VRH), where p = ¼, and the carrier hopping depends on energy. However, at lower temperatures, the coulomb interaction between charge carriers becomes important and Efros-Shklosvkii variable hopping (ES-VRH) conduction, where p=1/2, must be included to describe the total conductivity. To correlate changes in electrical conductivity to changes in the local crystalline order, the transverse optical (TO) and transverse acoustic (TA) modes of the Raman spectra were studied to relate changes in short- and mid-range order to the effects of growth temperature, boron, and hydrogen incorporation. With an increase of hydrogen and/or growth temperature, both short and mid-range order improve, whereas the addition of boron results in the degradation of short range order. It is seen that there is a direct correlation between the ...
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An Electro- Magneto-static Field for Confinement of Charged Particle Beams and Plasmas

An Electro- Magneto-static Field for Confinement of Charged Particle Beams and Plasmas

Date: May 2014
Creator: Pacheco, Josè L.
Description: A system is presented that is capable of confining an ion beam or plasma within a region that is essentially free of applied fields. An Artificially Structured Boundary (ASB) produces a spatially periodic set of magnetic field cusps that provides charged particle confinement. Electrostatic plugging of the magnetic field cusps enhances confinement. An ASB that has a small spatial period, compared to the dimensions of a confined plasma, generates electro- magneto-static fields with a short range. An ASB-lined volume thus constructed creates an effectively field free region near its center. It is assumed that a non-neutral plasma confined within such a volume relaxes to a Maxwell-Boltzmann distribution. Space charge based confinement of a second species of charged particles is envisioned, where the second species is confined by the space charge of the first non-neutral plasma species. An electron plasma confined within an ASB-lined volume can potentially provide confinement of a positive ion beam or positive ion plasma. Experimental as well as computational results are presented in which a plasma or charged particle beam interact with the electro- magneto-static fields generated by an ASB. A theoretical model is analyzed and solved via self-consistent computational methods to determine the behavior and equilibrium ...
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Electrochemical Depostion of Bismuth on Ruthenium and Ruthenium Oxide Surfaces

Electrochemical Depostion of Bismuth on Ruthenium and Ruthenium Oxide Surfaces

Date: May 2012
Creator: Taylor, Daniel M.
Description: Cyclic voltammetry experiments were performed to compare the electrodeposition characteristics of bismuth on ruthenium. Two types of electrodes were used for comparison: a Ru shot electrode (polycrystalline) and a thin film of radio-frequency sputtered Ru on a Ti/Si(100) support. Experiments were performed in 1mM Bi(NO3)3/0.5M H2SO4 with switching potentials between -0.25 and 0.55V (vs. KCl sat. Ag/AgCl) and a 20mV/s scan rate. Grazing incidence x-ray diffraction (GIXRD) determined the freshly prepared thin film electrode was hexagonally close-packed. After thermally oxidizing at 600°C for 20 minutes, the thin film adopts the tetragonal structure consistent with RuO2. a hydrated oxide film (RuOx?(H2O)y) was made by holding 1.3V on the surface of the film in H2SO4 for 60 seconds and was determined to be amorphous. Underpotential deposition of Bi was observed on the metallic surfaces and the electrochemically oxidized surface; it was not observed on the thermal oxide.
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Electrochemical Quartz Crystal Microbalance Study Of Bismuth Underpotential Deposition On Ruthenium And On Electrochemically Formed Ruthenium Oxide

Electrochemical Quartz Crystal Microbalance Study Of Bismuth Underpotential Deposition On Ruthenium And On Electrochemically Formed Ruthenium Oxide

Date: December 2011
Creator: Lin, Po-Fu
Description: Kinetics and thermodynamics of bismuth (Bi) underpotential deposition (UPD) on ruthenium (Ru) and on electrochemically formed Ru oxide are studied using electrochemical quartz crystal microbalance technique. The Bi UPD and Bi bulk deposition are observed both on Ru and on electrochemically formed Ru oxide electrodes. The anodic peak potential of Bi UPD shifts slightly to positive potential as the scan rate increases. The peak current ratio (IAnode/ICathode) of Bi UPD and Bi bulk increases as the scan rate increases. Bi monolayer coverage calculated from mass (MLMass) and from charge (MLCharge) with scan rates dependent are compared both in Bi UPD region and in Bi bulk region. Stability and oxidation time effects are also investigated. Bi UPD on Ru and on electrochemically formed Ru oxide are quasi-reversible, scan rate independent, oxidation time dependent, and have higher plating efficiency on Ru. However, Bi bulk deposition on Ru and on electrochemically formed Ru oxide are quasi-reversible, scan rate dependent, oxidation time independent, and have higher plating efficiency on electrochemically formed Ru oxide. Both Bi UPD adatoms and Bi bulk are unstable in 0.5M H2SO4.
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Electrochemical Synthesis and Applications of Layered Double Hydroxides and Derivatives

Electrochemical Synthesis and Applications of Layered Double Hydroxides and Derivatives

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Date: August 2015
Creator: Kahl, Michael S.
Description: Layered double hydroxides (LDH) are a class of anionic clay with alternating layers of positive and negative charge. A metal hydroxide layer with divalent and trivalent metals with a positive charge is complemented by an interlayer region containing anions and water with a negative charge. The anions can be exchanged under favorable conditions. Hydrotalcite (Mg6Al2(OH)16[CO3]·4H2O) and other variations are naturally occurring minerals. Synthetic LDH can be prepared as a powder or film by numerous methods. Synthetic LDH is used in electrode materials, adsorbents, nuclear waste treatment, drug delivery systems, water treatment, corrosion protection coatings, and catalysis. In this dissertation Zn-Al-NO3 derivatives of zaccagnaite (Zn4Al2(OH)12[CO3]·3H2O) are electrochemically synthesized as films and applied to sensing and corrosion resistance applications. First, Zn-Al-NO3 LDH was potentiostatically electrosynthesized on glassy carbon substrates and applied to the electrochemical detection of gallic acid and caffeic acid in aqueous solutions. The modified electrode was then applied to the detection of gallic acid in green tea samples. The focus of the work shifts to corrosion protection of stainless steel. Modified zaccagnaite films were electrodeposited onto stainless steel in multiples layers to reduce defects caused by drying of the films. The films were deposited using a step potential method. The ...
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Electrochemically Deposited Metal Alloy-silicate Nanocomposite Corrosion Resistant Materials

Electrochemically Deposited Metal Alloy-silicate Nanocomposite Corrosion Resistant Materials

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Date: May 2013
Creator: Conrad, Heidi Ann
Description: Zinc-nickel ?-phase silicate and copper-nickel silicate corrosion resistant coatings have been prepared via electrochemical methods to improve currently available corrosion resistant materials in the oil and gas industry. A layered silicate, montmorillonite, has been incorporated into the coatings for increased corrosion protection. For the zinc nickel silicate coatings, optimal plating conditions were determined to be a working pH range of 9.3 -9.5 with a borate based electrolyte solution, resulting in more uniform deposits and better corrosion protection of the basis metal as compared to acidic conditions. Quality, strongly adhering deposits were obtained quickly with strong, even overall coverage of the metal substrate. The corrosion current of the zinc-nickel-silicate coating is Icorr = 3.33E-6 for a borate based bath as compared to a zinc-nickel bath without silicate incorporation (Icorr = 3.52E-5). Step potential and direct potential methods were examined, showing a morphological advantage to step potential deposition. The effect of borate addition was examined in relation to zinc, nickel and zinc-nickel alloy deposition. Borate was found to affect the onset of hydrogen evolution and was examined for absorption onto the electrode surface. For copper-nickel silicate coatings, optimal conditions were determined to be a citrate based electrolytic bath, with pH = 6. ...
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