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Assessment of Sediment Runoff from Natural Gas Well Development Sites. (open access)

Assessment of Sediment Runoff from Natural Gas Well Development Sites.

Storm water sediment runoff from disturbed landscapes has the potential to impair aquatic environments. Small construction sites of 1-5 acres in the United States are currently regulated by the United States Environmental Protection Agency to minimize storm water runoff damages to the environment. Gas well construction sites are similar to other construction sites in how the landscape is altered, but are not similarly regulated. This study identified sediment runoff from gas well development sites by collecting it in traps and weirs, and by measuring sediment debris lobes. Sediment primarily consisted of silt and clay sized particles. Sediments from two gas well sites formed five debris lobes that ranged in size from 325 to 3,290 square feet. Sediment loadings estimated from the debris lobes averaged 57.1 tons per year/acre. Future studies should focus on further quantification of sediment movement off of gas well sites and identify effective erosion control methods.
Date: May 2007
Creator: Havens, David Loran
System: The UNT Digital Library
Exploring Fear and Freud's The Uncanny (open access)

Exploring Fear and Freud's The Uncanny

Fear is one of the oldest and most basic of human emotions. In this thesis, I will explore the topic of fear in relation to literature, both a staple of the horror genre as well as a device in literary works, as well as in my own writings. In addition, I will use Sigmund Freud's theory of the “uncanny” as a possible device to examine the complexities of fear and its effects both on the mind and body through the medium of literature, and, more specifically, where and how these notions are used within my own short stories. By exploring how and why certain fears are generated, we may be able to better examine our own reactions in this regard.
Date: May 2007
Creator: Grizzle, Eric
System: The UNT Digital Library
An Analytical Study of Mily Alekseyevich Balakirev's Musical Style in his Early Piano and Orchestra Works: Grande Fantaisie on Russian Folk Songs and Concerto Op.1 in F# Minor. (open access)

An Analytical Study of Mily Alekseyevich Balakirev's Musical Style in his Early Piano and Orchestra Works: Grande Fantaisie on Russian Folk Songs and Concerto Op.1 in F# Minor.

Balakirev's two early piano and orchestra works, Grande Fantaisie on Russian Folk Songs and Concerto Op. 1 in F# Minor, were composed in the middle of the nineteenth century when in Russia there were no particularly important works for piano and orchestra. Balakirev was still a teenager when he wrote these two pieces and unfortunately both remained unfinished. However the beauty and remarkable compositional achievement of these works should be highly recognized. There are six chapters in this essay. The general background, purpose and the state of research are discussed in the first chapter. The second chapter presents Balakirev's biographical information and the overview of his works for piano and orchestra is stated in Chapter III. Individual works, Grande Fantaisie and Concerto in F# Minor are discussed in the chapters IV and V, which including discussing compositional background, analysis and diagram of structural schemes. The last chapter concludes with Balakirev's contribution to Russian music and the development of the Russian concerto coming into its own. It deals particularly with Balakirev's approach to folk songs, which gives the concerto a unique Russian aesthetic, in addition to his ability to write in the European tradition.
Date: May 2007
Creator: Kim, Miyang
System: The UNT Digital Library
The Significance of Dmitri Shostakovich's Piano Sonata Op.12 (open access)

The Significance of Dmitri Shostakovich's Piano Sonata Op.12

The aspiration of this dissertation is to bring forth the significance of Shostakovich's Piano Sonata Op.12. This sonata is a hybrid of the German musical tradition, Russian Modernism, and Liszt's thematic transformation technique. It demonstrates Shostakovich's highly intellectual compositional skills influenced by the education that he received at St. Petersburg Conservatory as well as the exposure to modern music in the 1920s. This dissertation discusses composition techniques, such as the harmonic piers adapted from Alexander Scriabin, neighboring-tone technique, which involves the application of semitone cell throughout the piece, as well as the technique of thematic transformation borrowed from Liszt. These all come together by Shostakovich's design in the most controversial sonata form. The Piano Sonata Op.12 also sheds light on Shostakovich's early compositional style and proves its contribution to the evolution of sonata genre in the twentieth-century.
Date: May 2007
Creator: Kan, Ling-Yu
System: The UNT Digital Library
Who Benefits? The Effects of Foreign Aid and Foreign Direct Investment on Human Rights (open access)

Who Benefits? The Effects of Foreign Aid and Foreign Direct Investment on Human Rights

The global emphasis on human rights has generated a surge of studies into what causes regimes to abuse the basic rights of their citizens. Causes of abuse can be internal or external in nature, based on economics, politics or cultures. This study examines the effects of foreign aid and foreign direct investment on three types of human rights: personal integrity, civil and political, and subsistence. I perform ordinary least squares regression analyses with panel-corrected standard errors on a pooled cross-sectional time series design incorporating 127 countries from 1976 to 1996. While my results are not significant, it is important to observe that there is a tendency toward negative relationships for the majority of the analyses.
Date: May 2007
Creator: Moses, Misty
System: The UNT Digital Library
The Effects of Combining Positive and Negative Reinforcement During Training. (open access)

The Effects of Combining Positive and Negative Reinforcement During Training.

The purpose of this experiment was to compare the effects of combining negative reinforcement and positive reinforcement during teaching with the effects of using positive reinforcement alone. A behavior was trained under two stimulus conditions and procedures. One method involved presenting the cue ven and reinforcing successive approximations to the target behavior. The other method involved presenting the cue punir, physically prompting the target behavior by pulling the leash, and delivering a reinforcer. Three other behaviors were trained using the two cues contingent on their occurrence. The results suggest that stimuli associated with both a positive reinforcer and an aversive stimulus produce a different dynamic than a situation that uses positive reinforcement or punishment alone.
Date: May 2007
Creator: Murrey, Nicole A.
System: The UNT Digital Library
Map-based cloning of the NIP gene in model legume Medicago truncatula. (open access)

Map-based cloning of the NIP gene in model legume Medicago truncatula.

Large amounts of industrial fertilizers are used to maximize crop yields. Unfortunately, they are not completely consumed by plants; consequently, this leads to soil pollution and negative effects on aquatic systems. An alternative to industrial fertilizers can be found in legume plants that provide a nitrogen source that is not harmful for the environment. Legume plants, through their symbiosis with soil bacteria called rhizobia, are able to reduce atmospheric nitrogen into ammonia, a biological nitrogen source. Establishment of the symbiosis requires communication on the molecular level between the two symbionts, which leads to changes on the cellular level and ultimately results in nitrogen-fixing nodule development. Inside the nodules hypoxic environment, the bacterial enzyme nitrogenase reduces atmospheric nitrogen to ammonia. Medicago truncatula is the model legume plant that is used to study symbiosis with mycorrhiza and with the bacteria Sinorhizobium meliloti. The focus of this work is the M. truncatula nodulation mutant nip (numerous infections and polyphenolics). The NIP gene plays a role in the formation and differentiation of nodules, and development of lateral roots. Studying this mutant will contribute knowledge to understanding the plant response to infection and how the invasion by rhizobia is regulated. Previous genetic mapping placed NIP …
Date: May 2007
Creator: Morris, Viktoriya
System: The UNT Digital Library
The use of democratic institutions as a strategy to legitimize authoritarian rule. (open access)

The use of democratic institutions as a strategy to legitimize authoritarian rule.

Numerous authoritarian states use institutions usually associated with democratic regimes like a constitution, elections, and a legislature. This seems to be counterintuitive. Authoritarian regimes should rather shrink away from democratic institutions. Elections can be won by the opposition and legislatures can make decisions against the interests of the ruler. So, why do autocratic regimes install institutions which limit their power and threaten their survival in office? Assuming actors behave rationally, one should expect authoritarian rulers only to introduce procedures working in their favor. This study looks at the effect of institutions in authoritarian regimes. The findings suggest that legislatures significantly lower the chances of regime breakdown in the long run. However, particularly in election years, authoritarian regimes are facing a higher likelihood of failure.
Date: May 2007
Creator: Michalik, Susanne
System: The UNT Digital Library
A Historical and Analytical Examination of the Stravinsky Octet for Wind Instruments, with a Guide to Performance Preparation of the Two Trumpet Parts (open access)

A Historical and Analytical Examination of the Stravinsky Octet for Wind Instruments, with a Guide to Performance Preparation of the Two Trumpet Parts

The Octuor pour instruments a vents (or Octet), written in 1922-1923 by Igor Stravinsky, is a piece in three movements for a curious assortment of instruments: two trumpets, two trombones, flute, clarinet and two bassoons. It is one of four influential chamber works for winds by Stravinsky to include trumpet. Of these pieces, the Octet contains the fewest number of players but is no less complex and important in Stravinsky's oeuvre. The Octet helped mark the beginning of the neoclassical period in twentieth-century music. Chapter 2 examines the life and musical background of the composer. It also reveals the history surrounding the origin of the Octet and its role in neoclassicism. Chapter 3 discusses the role of the Octet in the wind ensemble and orchestral repertoire, and includes a representative performance history, including the premiere. Chapter 4 provides analytical insights into the construction and format of the piece. Chapter 5 provides suggestions regarding style in Stravinsky's music, including interviews with important figures in the trumpet world. Chapter 6 concludes the guide with specific suggestions regarding preparation and performance of the Octet.
Date: May 2007
Creator: Wood, James J.
System: The UNT Digital Library
Criminal Investigations: The Impact of Patrol Officers on Solving Crime (open access)

Criminal Investigations: The Impact of Patrol Officers on Solving Crime

This two-part study of the criminal investigation process first evaluated the frequency with which patrol officers solve cases assigned to the investigations division and then examined how detectives spent their time, both on case assignments and on other activity not related to current case assignment. Cases assigned to the investigations division for follow up were examined to determine how often a case was cleared by the patrol officer. The detective's time was then evaluated in order to determine how much time detectives spent on investigative tasks and other activities. This study confirms that the patrol officer should be given more time to conduct preliminary investigations for specific cases, and that tasks performed by detectives could be shifted to other personnel in the department. Both actions should serve to positively impact case clearance rates.
Date: May 2007
Creator: Womack, Charissa L.
System: The UNT Digital Library
An investigation of beliefs and practices of conservative Protestant parents and the cultural applicability of child parent relationship therapy. (open access)

An investigation of beliefs and practices of conservative Protestant parents and the cultural applicability of child parent relationship therapy.

The purpose of this study was to conduct a survey to identify the beliefs and practices of conservative Protestant parents, which assisted in clarifying the assertions in the current literature regarding conservative Protestant parenting. Additionally, this researcher sought to determine the applicability of child parent relationship therapy (CPRT), a filial therapy model based upon the principles of child centered play therapy, for conservative Protestant parents by ascertaining the need for cultural modifications. Beliefs and practices of conservative Protestants were measured using the Protestant Parenting Inventory (PPI), an original instrument developed through a series of focus groups and pilot testings. The population comprised 148 mothers and fathers from 4 Southern Baptist churches in and around the Dallas/Fort Worth metroplex. Exploratory factor analysis was applied to the data in order to increase internal consistency estimates and percent of explained variance. Criterion coding of demographic data allowed a multiple regression analysis to determine which demographic variables were significant predictors of participant responses on the PPI. Descriptive statistics allowed the researcher to investigate the compatibility of conservative Protestants and CPRT. Results of this study both confirm and refute past findings regarding conservative Protestants. Results also revealed the need for some cultural modifications to CPRT …
Date: May 2007
Creator: McClung, Tracy M.
System: The UNT Digital Library
Analyzing the Effects of a Performance Pay Plan on Manager Performance in an Accounting Firm (open access)

Analyzing the Effects of a Performance Pay Plan on Manager Performance in an Accounting Firm

This study examined the effect of a score card¬-based performance pay plan in a professional services firm. The plan was implemented in response to a decreasing trend in productivity and a desire for a formal incentive compensation plan. Performance of manager and senior manager accountants were analyzed across two departments over a five year period. A definitive account of the effects of the intervention is limited by the case-¬study design, but the data does suggest that the performance pay plans used did not adversely affect performances. Design limitations of the plan and future research are also discussed.
Date: May 2007
Creator: McDaniel, Sarah Curran
System: The UNT Digital Library
Toward a philosophy of water: Politics of the pollution and damming along the Ganges River. (open access)

Toward a philosophy of water: Politics of the pollution and damming along the Ganges River.

This thesis sets out to develop a beginning of a philosophy of water by considering philosophical implications of ecological crises currently happening along the waters of the Ganges River. In my first chapter, I give a historical account of a philosophy of water. In my second chapter, I describe various natural and cultural representations of the Ganges, accounting for physical features of the river, Hindu myths and rituals involving the river, and ecological crises characterized by the pollution and damming of the river. In my third and final chapter, I look into the philosophical implications of these crises in terms of the works of the contemporary philosopher Bruno Latour.
Date: May 2007
Creator: McAnally, Elizabeth Ann
System: The UNT Digital Library
Examining the effects of scheduled course time on mathematics achievement in high school students. (open access)

Examining the effects of scheduled course time on mathematics achievement in high school students.

This study was designed to determine the effects of two different schedule types on mathematics achievement in public high school students. The instruments used included the Texas Assessment of Knowledge and Skills, given annually to all students in grades 3 through 11, the Texas Algebra I end-of-course examination, given as a district option to Algebra I students, and student final course grades as determined by classroom teachers. The study compared students' performance in these three areas during the 2004-2005 academic year in one suburban school district in North Texas. The study considers the type of schedule, either traditional or 8-block, between students in teachers' classes who teach the same course on both schedules concurrently. This study also investigates a qualitative aspect by including a short opinion survey of teachers' perceptions regarding student academic performance, teacher satisfaction and retention, and the ability to accomplish curricular goals. Findings from this research suggest course schedule does not have significant effects on student academic performance as measured using analyses of covariance comparisons with a 0.05 alpha-level, leading to the conclusion that a particular course schedule does not adversely impact student performance on academic measures. However, in some comparisons conducted within the course of the …
Date: May 2007
Creator: Mallory, Kelli D.
System: The UNT Digital Library
Correlates of Recidivism: A Study Examining the Differences Between First Time Felony Probationers and Recidivist Felony Probation Offenders (open access)

Correlates of Recidivism: A Study Examining the Differences Between First Time Felony Probationers and Recidivist Felony Probation Offenders

The purpose of this study is to explore the differences and characteristics between first time felony probationer and recidivist felony probation offender. The importance of said studies grows significantly, given current trends of sentencing offenders to probation. Using archived data on random sample of felony offenders in 2000 and based on information acquired and maintained by the Denton County Community Supervision and Corrections Department (CSCD), the study consists of 40 first time felony offenders and 40 recidivist felony offender placed on probation during the year 2000. The method consists of a longitudinal comparison model. To examine the research question, descriptive statistics are used to compare basic demographics. Then, in order to answer the research question bi-variate significant tests, Chi-square and Independent Sample T-tests were employed when appropriate. Results indicate differences between first time felony probation offenders and recidivist felony probationers.
Date: May 2007
Creator: Lynton, Eddy
System: The UNT Digital Library
Bacterial Challenge in Lumbricus Terrestris: A Terrestrial Invertebrate Immunotoxicity Model. (open access)

Bacterial Challenge in Lumbricus Terrestris: A Terrestrial Invertebrate Immunotoxicity Model.

A bacterial challenge assay was developed utilizing the earthworm, Lumbricus terrestris, in order to assess potential immunotoxic effects from exposure to specific polychlorinated biphenyl congeners. Earthworms were inoculated with Aeromonous hydrophila, establishing a 10-day LD50. In vitro assays for effects of PCBs on phagocytosis agreed with mammalian studies, demonstrating potent suppression of phagocytosis by the non-coplanar PCB congener 138 and no suppression by the coplanar congener 126. However, when the effects of the two PCB congeners were evaluated for suppression of resistance to a whole animal infection challenge assay, coplanar PCB 126 decreased the ability of L. terrestris to withstand infection while non-coplanar PCB 138 did not.
Date: May 2007
Creator: McDonald, Jennifer C.
System: The UNT Digital Library
Formation and Quantification of Corrosion Deposits in the Power Industry (open access)

Formation and Quantification of Corrosion Deposits in the Power Industry

The presence of deposits on the secondary side of pressurized water reactor (PWR) steam generator systems is one of the main contributors to the high maintenance costs of these generators. Formation and transport of corrosion products formed due to the presence of impurities, metals and metallic oxides in the secondary side of the steam generator units result in formation of deposits. This research deals with understanding the deposit formation and characterization of deposits by studying the samples collected from different units in secondary side system at Comanche Peak Steam Electric Station (CPSES). Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) have been used for studying the phases, morphologies and compositions of the iron oxides formed at Unit 1 and Unit 2 of secondary side of steamgenerator systems. Hematite and magnetite were found to be the dominant phases of iron oxides present in the units. Fe, Cr, O, Ni, Si, Cl and Cu were found in samples collected from both the units. A qualitative method was developed to differentiate iron oxides using laser induced breakdown spectroscopy (LIBS) based on temporal response of iron oxides to a high power laser beam. A quantitative FTIR technique was …
Date: May 2007
Creator: Namduri, Haritha
System: The UNT Digital Library
An Analysis of the Benefits of the Student Success Initiative in the 3rd and 5th Grades in a District in Texas. (open access)

An Analysis of the Benefits of the Student Success Initiative in the 3rd and 5th Grades in a District in Texas.

The state of Texas passed the Student Success Initiative (SSI) in 1999 which requires all 3rd graders to pass the reading portion of the Texas Assessment of Knowledge and Skills (TAKS) test to be promoted to the 4th grade, and for 5th graders to pass the reading and math portions of the TAKS test to be promoted to the 6th grade. Beginning in spring 2008, 8th graders will also need to pass the reading and math portions of the TAKS test to be promoted to the 9th grade. The purpose of this study was to examine the academic performance of 3rd and 5th grade students who did not meet the passing standard on the TAKS test and were retained during the 2005-2006 school year. The population of this study included 33 3rd graders and 49 5th graders who were retained during the 2005-2006 school year due to not meeting the promotion requirements of the SSI. There was also a second population of 49 5th graders who were retained in 3rd grade during the 2003-2004 school year due to not meeting the promotion requirements of the SSI. These students were enrolled in the 5th grade for the first time during the …
Date: May 2007
Creator: Neblett, Pamela S.
System: The UNT Digital Library
Beyond the "Year of Song": Text and Music in the Song Cycles of Robert Schumann after 1848 (open access)

Beyond the "Year of Song": Text and Music in the Song Cycles of Robert Schumann after 1848

In recent years scholars have begun to re-evaluate the works, writings, and life of Robert Schumann (1810-1856). One of the primary issues in this ongoing re-evaluation is a reassessment of the composer's late works (roughly defined as those written after 1845). Until recently, the last eight years of Schumann's creative life and the works he composed at that time either have been ignored or critiqued under an image of an illness that had caused periodic breakdowns. Schumann's late works show how his culture and the artists communicating within that culture were transformed from the beginning to the middle of the nineteenth century. These late works, therefore, should be viewed in the context of Schumann's output as a whole and in regard to their contributions to nineteenth-century society. Schumann's contributions, specifically to the genre of the song cycle from 1849 to 1852, are among his late compositional works that still await full reconsideration. A topical study, focusing on three themes of selections from his twenty-three late cycles, will provide a critical evaluation of Schumann's compositional output in the genre of the song cycle. First, Schumann's political voice will be examined. The political events that led to the mid-nineteenth-century revolutions inspired crucial …
Date: May 2007
Creator: Ringer, Rebecca Scharlene
System: The UNT Digital Library
Layered Double Hydroxides as Anion- and Cation-Exchanging Materials (open access)

Layered Double Hydroxides as Anion- and Cation-Exchanging Materials

Layered double hydroxides (LDH) have been principally known as anion-exchanging, clay-like materials for several decades, and continues to be the main driving force for current and future research. The chemical interactions of LDH, with transition metallocyanides, have been a popular topic of investigation for many years, partly due to the use of powder x-ray diffraction and infrared spectroscopy as the main characterization tools. Each transition metallocyanide has a characteristic infrared stretching frequency that can be easily observed, and their respective sizes can be observed while intercalated within the interlayer of the LDH. The ability of LDH to incorporate metal cations or any ions/molecules/complexes, that have a postive charge, have not been previously investigated, mainly due to the chemical and physical nature of LDH. The possibility of cationic incorporation with LDH would most likely occur by surface adsorption, lattice metal replacement, or by intercalation into the LDH interlayers. Although infrared spectroscopy finds it main use through the identification of the anions incorporated with LDH, it can also be used to study and identify the various active and inactive bending and stretching modes that the metal hydroxide layers have.
Date: May 2007
Creator: Richardson, Mickey Charles
System: The UNT Digital Library
Determining the Relationship Between Motivation and Academic Outcomes Among Students in the Health Professions. (open access)

Determining the Relationship Between Motivation and Academic Outcomes Among Students in the Health Professions.

Admissions processes for health professions programs result in students entering these programs academically homogeneous. Yet some students have great difficulty with the programs. Research has shown a limited ability of traditional academic indicators to predict successful outcomes for health professions education. The purpose of this study was to examine the relationship between learning motivation and academic outcomes for students in health professions programs. The Modified Archer Health Professions Motivation Scale (MAHPMS) and a demographic survey were administered at orientation to 131 medical and 29 physician assistant students at the University of North Texas Health Science Center in the fall of 2005. At the end of the semester, the same version of the MAHPMS was administered, and final course grades and semester averages were collected. Descriptive statistics were analyzed for all the study variables. Analysis of variance was utilized to examine within subjects and between subjects differences for the learning motivation scores among programs and demographic categories. Linear regression analyses were used to determine the relationship between learning motivation scores and end-of-semester grades. And finally, logistic regression was performed to explore the ability of the motivation scores to predict academically high-risk students. Approximately three-fourths of the students indicated a preference for …
Date: May 2007
Creator: Reed, Linda E.
System: The UNT Digital Library
State and local level implementation of schoolwide positive behavior support: An examination of the Texas Behavior Support Initiative (TBSI). (open access)

State and local level implementation of schoolwide positive behavior support: An examination of the Texas Behavior Support Initiative (TBSI).

This study examined the current status of schoolwide positive behavior support efforts in Texas. The study specifically (a) examined the impact of statewide positive behavior interventions and supports (PBIS) training on the rates of discipline records, in-school ¬suspensions, out-¬of¬-school suspensions, disciplinary alternative education placements, and expulsions of public schools in Texas; (b) investigated the overall effectiveness of schoolwide positive behavior support; and (c) determined the differences between rates of discipline records, in-school ¬suspensions, out-¬of¬-school suspensions, disciplinary alternative education placements, and expulsions in schools participating in the Texas Behavior Support Initiative (TBSI): Schoolwide PBS Project when compared with matching schools who did not participate in the project. This study demonstrated that schools can significantly reduce problem behavior in their schools when implementing PBIS with fidelity. Creating effective systems of PBIS required training, coaching, and on¬site technical assistance by trained and experienced PBIS facilitators.
Date: May 2007
Creator: Schultz, Edward K.
System: The UNT Digital Library
Susan Botti's  Cosmosis: A Conductor's Analysis with Performance Considerations (open access)

Susan Botti's Cosmosis: A Conductor's Analysis with Performance Considerations

In 2005, composer Susan Botti won the coveted Prix de Rome in musical composition and spent eleven months in residency at the American Academy in Rome. That same year, the University of Michigan Wind Symphony, under the direction of Michael Haithcock, premiered her exciting new work Cosmosis at the College Band Directors National Association Conference in New York City. The bi-annual conference is a venue for the premiere of new works for wind ensembles and bands, and the 2005 conference saw the world premiere of nine works for winds and percussion, many of which were performed in the legendary Carnegie Hall. What made the debut performance of Cosmosis exciting and notable was the composer's own appearance as soprano soloist, and the inclusion of a chorus of women augmenting the ensemble of winds and percussion. Such a combination of elements is unique, and created a fresh and powerful sonority. Botti's inventive approach to composition has expanded the repertoire for both women's chorus and wind ensemble with this distinctive work. This study is intended to serve as a guide to the study and performance of Cosmosis. The information provides a detailed examination of the work from its conception to its premiere performance. …
Date: May 2007
Creator: Schroeder, Angela
System: The UNT Digital Library
Surface Engineering and Characterization of Laser Deposited Metallic Biomaterials (open access)

Surface Engineering and Characterization of Laser Deposited Metallic Biomaterials

Novel net shaping technique Laser Engineered Net shaping™ (LENS) laser based manufacturing solution (Sandia Corp., Albuquerque, NM); Laser can be used to deposit orthopedic implant alloys. Ti-35Nb-7Zr-5Ta (TNZT) alloy system was deposited using LENS. The corrosion resistance being an important prerequisite was tested electrochemically and was found that the LENS deposited TNZT was better than conventionally used Ti-6Al-4V in 0.1N HCl and a simulated body solution. A detailed analysis of the corrosion product exhibited the presence of complex oxides which are responsible for the excellent corrosion resistance. In addition, the in vitro tests done on LENS deposited TNZT showed that they have excellent biocompatibility. In order to improve the wear resistance of the TNZT system boride reinforcements were carried out in the matrix using LENS processing. The tribological response of the metal matrix composites was studied under different conditions and compared with Ti-6Al-4V. Usage of Si3N4 balls as a counterpart in the wear studies showed that there is boride pullout resulting in third body abrasive wear with higher coefficient of friction (COF). Using 440C stainless steel balls drastically improved the COF of as deposited TNZT+2B and seemed to eliminate the effect of “three body abrasive wear,” and also exhibited superior …
Date: May 2007
Creator: Samuel, Sonia
System: The UNT Digital Library