Degree Level

States

The Effects of District Expenditure Per Pupil and Low Socio-Economic Status on the Grade 10, 2000 and 2002 Disaggregated Student Performance Scores on the TAAS

Access: Use of this item is restricted to the UNT Community
Educators can no longer simply look at student totals to distribute instructional dollars. Databased decision-making must be instituted to overcome achievement gaps between white and non-white students. In low-socioeconomic (SES) settings, districts must increase expenditure per pupil (EPP) as low-SES rates rise for all students as district administrators must be in a position to show product rather than process. It was attempted to determine if a positive or negative relationship existed between Anglo, Hispanic, and African-American student test scores and wealth factors on the Texas Assessment of Academic Skills tests in 2000 and 2002. Wealth factors studied included EPP and SES. Data analysis was carried out on 974 independent and consolidated school districts in Texas. Low-SES was found to be a negative predictor of higher test performance on standardized reading and mathematics tests. To varied degrees, low-SES affected all students from all ethnicities as well as affluent students. EPP was attributed with a positive effect on student test performance. Increases of $1,000 or more at one time produce performance increases from 0.20 to 0.40 points. In making specific recommendations, the researcher advises increasing expenditures low-SES districts, schools, and classrooms through the creation of specific district linear equations exhibited in this …
Date: May 2006
Creator: Iker, Gary A.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Dimension spectrum and graph directed Markov systems.

Access: Use of this item is restricted to the UNT Community
In this dissertation we study graph directed Markov systems (GDMS) and limit sets associated with these systems. Given a GDMS S, by the Hausdorff dimension spectrum of S we mean the set of all positive real numbers which are the Hausdorff dimension of the limit set generated by a subsystem of S. We say that S has full Hausdorff dimension spectrum (full HD spectrum), if the dimension spectrum is the interval [0, h], where h is the Hausdorff dimension of the limit set of S. We give necessary conditions for a finitely primitive conformal GDMS to have full HD spectrum. A GDMS is said to be regular if the Hausdorff dimension of its limit set is also the zero of the topological pressure function. We show that every number in the Hausdorff dimension spectrum is the Hausdorff dimension of a regular subsystem. In the particular case of a conformal iterated function system we show that the Hausdorff dimension spectrum is compact. We introduce several new systems: the nearest integer GDMS, the Gauss-like continued fraction system, and the Renyi-like continued fraction system. We prove that these systems have full HD spectrum. A special attention is given to the backward continued fraction …
Date: May 2006
Creator: Ghenciu, Eugen Andrei
Object Type: Thesis or Dissertation
System: The UNT Digital Library

A study of continuing bonds and their impact on life attitudes in parents of murdered children.

Access: Use of this item is restricted to the UNT Community
For most of the past century, the positive outcome of grief in the West was characterized as the relinquishment of the bond to the deceased. Phrases such as "let go", "move on", and "get over it" were, and continue to be, common to the language of this pursuit. This 'breaking bonds' perspective does not take into account other means of grief resolution, nor does it consider historical or cultural findings. Consequently, reports of bereaved parents who indicate resolution of grief yet maintain a continued relationship with their deceased child were not given much attention until the 1990s. This research employed a Durkheimian approach, taking the social bond as the starting point of inquiry and examined continuing bonds of parents to their murdered children. How these bonds were related to the parents' attitudes of re-investing in life and their level of grief was measured. The relationship between the parents' level of grief and their life attitudes was also assessed. The sample consisted of 46 parents living in North Texas whose child had been murdered three or more years ago. A triangulated methodology was utilized and the data were collected by means of participant observation, unstructured interviews, and a mailed questionnaire which …
Date: May 2006
Creator: Haag, Marcy J.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

The Long Chorale Preludes of J. S. Bach (1685-1750): Study of Accompaniments together with Three Recitals of Selected Works by Dietrich Buxtehude (1637-1707), J. S. Bach, Louis Vierne (1870-1937), and Others

Access: Use of this item is restricted to the UNT Community
Johann Sebastian Bach's chorale preludes are varied and artistic not only in the treatment of chorale melodies, but also in the accompaniments of those chorale melodies. This study examines the accompaniments of Bach's long chorale preludes, focusing on identifying the various types and the characteristics that make them unique. This study investigates the two broad categories of accompaniments depending on whether the motives are chorale-derived or independent of the chorale. While the chorale prelude accompaniments in the first large group are closely related, the accompaniments of the chorale preludes in the second group stand independently and illustrate the vast range of Bach's compositional skill. Both groups demonstrate Bach's interest in expanding his predecessors' models, a trait that can be traced throughout all of Bach's compositional history.
Date: May 2006
Creator: Lim, Aesook
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Theory in Practice: Constructivism and the Technology of Instruction in an Authentic Project-based Computer Class

Access: Use of this item is restricted to the UNT Community
While literature in areas of constructivism learning theory, use of computer technology in education, and the implementation of project-based learning in the classroom have received widespread attention, there is no reported research that specifically examines the effectiveness of using a project-based learning model for computer technology instruction for pre-service teachers' programs in general, and in art education in particular. Thus, the research problem was to examine through pre- and post-test control-group experimental research design whether two different teaching methods, constructivism teaching approach (project-based learning) and traditional (step-by-step) teaching approach, result in significant differences in learning computer usage, the application of computer technical skills, design projects, and attitudes toward using of technology. The research was conducted at University of North Texas during the fall semester of 2004. Both quantitative and qualitative methods were used to collect the data. The quantitative data, collected from a pre-post test and pre and post questionnaire, was analyzed using a t-test. No significant difference was found between the groups as it relates to computer usage, one aspect of the application of computer technical skills (Photoshop usage), and attitudes towards technology. There was, however, a statistical difference between the groups in the use of the other aspect …
Date: May 2006
Creator: Esmaiel, Yousef Esmaiel
Object Type: Thesis or Dissertation
System: The UNT Digital Library

The impact of the Home Instruction for Parents of Preschool Youngsters (HIPPY) program on reading, mathematics, and language achievement of Hispanic English language learners.

Access: Use of this item is restricted to the UNT Community
This study sought to answer if the Home Instruction for Parents of Preschool Youngsters (HIPPY) program had a positive academic impact on Hispanic English language learners (ELL). HIPPY is a free, 2-year, home-based early intervention program for 4-and 5-year-old children. The program is intended to provide educational enrichment to at-risk children from poor and immigrant families, increase school readiness, and foster parent involvement in their children's education. A quasi-experimental design and quantitative measures were used to measure the academic success of Hispanic ELL students in reading, mathematics, and language arts. The sample included an experimental group and a purposeful control group. Hispanic students who attended an early childhood school as 4 year olds and participated in the HIPPY 4 and 5 programs were compared to Hispanic students who attended an early childhood school as 4 year olds and did not participate in HIPPY. Results from the Texas-mandated criterion referenced Texas Assessment Knowledge and Skills (TAKS™) Test and the TerraNova® and TerraNova SUPERA® norm referenced tests were used in this study. Results from the TAKS Reading and TAKS Mathematics Grade 3 and the TerraNova reading, language, mathematics, and total composite scores were analyzed using a one-way analysis of variance. The treatment …
Date: May 2006
Creator: García, Maria G.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Connective Technology Adoption in the Supply Chain: The Role of Organizational, Interorganizational and Technology-Related Factors.

Access: Use of this item is restricted to the UNT Community
Supply chain management (SCM) is an area that offers organizations significant opportunities for both cost reductions and revenue enhancement. In their article, "Supply Chain Management: Implementation Issues and Research Opportunities," Lambert, Cooper and Pagh defined SCM as the "integration of key business processes from end user through original suppliers that provides products, services, and information that add value for customers and other stakeholders." Adopting and implementing appropriate technology has emerged as a source of competitive advantage for supply chain member firms through the integration of business processes with suppliers and customers. It is important to understand the factors influencing an organization's decision to acquire such technology. In the context of this study, connective technologies are defined as wireless communication devices and their accompanying infrastructure and software which may enhance coordination among supply chain partners. Building on previous literature in the areas of supply chain management, marketing strategy, and organizational innovation, a model was developed to test the relationships between organizational, interorganizational, and technology-related factors and the adoption of advanced connective technology, using radio frequency identification (RFID) as the test case, in the supply chain. A Web-based survey of supply chain professionals was conducted resulting in 224 usable responses. The overall …
Date: May 2006
Creator: Neeley, Concha Kaye Ramsey
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Identification and characterization of an incomplete root hair elongation (IRE)-like gene in Medicago truncatula (L.) root nodules.

Access: Use of this item is restricted to the UNT Community
Cloning and molecular characterization of new genes constitutes a useful approach in studying the symbiotic interactions between the model plant Medicago truncatula and Synorhizobium meliloti. Large numbers of expressed sequence tags (ESTs) available for Medicago truncatula, along with numerous cDNA, oligonucleotides, and Affimetrix DNA microarray chips, represent useful tools for gene discovery. In an attempt to identify a new gene that might be involved in the process of nodulation in Medicago truncatula, preliminary data reported by Fedorova et al. (2002), who identified 340 putative gene products or tentative consensus sequences (TCs) expressed only in nodules, was used. This research was focused on TC33166 (TC103185), which has 3 ESTs in the TC, and whose strongest BLASTX hit of TC103185 is the incomplete root hair elongation (IRE) protein kinase-like protein (NP_192429) from Arabidopsis thaliana. The Arabidopsis IRE gene is required for normal root hair growth, and a role in apical growth was suggested (Oyama et al., 2002). Infection thread growth can be looked at as an inward growth of the root hair. Thus, TC103185 was a good candidate for identifying a gene that may be involved in early events of nodulation. MtIRE (GenBank accession AC122727) is organized in 17 exons and 16 …
Date: May 2006
Creator: Pislariu, Catalina Iulia
Object Type: Thesis or Dissertation
System: The UNT Digital Library

An Analysis of EC-4 Pre-Service Teacher Perceptions of Knowledge and Use of Classroom Discipline Techniques

Access: Use of this item is restricted to the UNT Community
The purpose of this study was to examine the perceptions of pre-service Texas Wesleyan University teachers' knowledge and use of classroom discipline techniques. The study was conducted to obtain data utilized for the evaluation of the research questions. A non-experimental, mixed research design using survey methodology was used. Part one of the Allen Classroom and Discipline Management Instrument (ACDMI) consisted of demographic information: current position, ethnicity, level of education, gender, age, teaching certification obtained, teaching certification anticipated to be obtained, type of teacher certification training, and number of clock hours received in discipline management. The demographic information was used as independent variables for comparing responses to survey items. Part two contained discipline management techniques from Skinner, Canter, Dreikurs, Gathercoal, Glasser, Faye and Funk, Curwin and Mendler, and Berne and Harris. These techniques were used to determine mean differences with the independent variables. Finally, part three was the qualitative section which consisted of four questions requesting information about helpful discipline techniques. The sample population consisted of 150 pre-service teachers from a small liberal arts university in Texas. Findings from the study indicated that EC-4 pre-service teachers' predicted use of discipline management techniques were the ones in which they were most knowledgeable. …
Date: May 2006
Creator: Short, Selena Gutierrez
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Democratic Pantheism in the Political Theory of Alexis de Tocqueville

Access: Use of this item is restricted to the UNT Community
According to Alexis de Tocqueville, humanity is entering a new age of political and social equality, a new epoch in which the human race has no historical example or experience. As a result, he holds humanity's future will be largely determined by the political and moral choices made in this transitional time. For Tocqueville, the new egalitarian era is a forgone conclusion, but for him, the pressing question is whether humanity will choose a future in which it enchains itself to new forms of tyranny, or, whether the human race can establish the political and moral institutions designed to assure human freedom and dignity. In Tocqueville's view, liberty or slavery are the two choices modern men and women have in front of them, and it is the intent of this dissertation to explore Tocqueville's warning in regard to the latter choice. Tocqueville warns us that modern democratic peoples must beware of the moral and political effects of a new type of political philosophy, a political theory he terms democratic pantheism. Democratic pantheism is a philosophic doctrine that treats egalitarianism as a "religion" in which all social and political striving is directed toward realizing a providentially ordained strict equality of conditions. …
Date: May 2006
Creator: Bearry, Brian Anthony
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Morale in the Western Confederacy, 1864-1865: Home Front and Battlefield

Access: Use of this item is restricted to the UNT Community
This dissertation is a study of morale in the western Confederacy from early 1864 until the Civil War's end in spring 1865. It examines when and why Confederate morale, military and civilian, changed in three important western states, Mississippi, Alabama, and Tennessee. Focusing on that time frame allows a thorough examination of the sources, increases the opportunity to produce representative results, and permits an assessment of the lingering question of when and why most Confederates recognized, or admitted, defeat. Most western Confederate men and women struggled for their ultimate goal of southern independence until Federal armies crushed those aspirations on the battlefield. Until the destruction of the Army of Tennessee at Franklin and Nashville, most western Confederates still hoped for victory and believed it at least possible. Until the end they drew inspiration from battlefield developments, but also from their families, communities, comrades in arms, the sacrifices already endured, simple hatred for northerners, and frequently from anxiety for what a Federal victory might mean to their lives. Wartime diaries and letters of western Confederates serve as the principal sources. The dissertation relies on what those men and women wrote about during the war - military, political, social, or otherwise - …
Date: May 2006
Creator: Clampitt, Brad R.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Photographic metaphors: A multiple case study of second language teachers' experiences using the acquisition model.

Access: Use of this item is restricted to the UNT Community
The purpose of this study was to examine and document second language teachers' perceptions of their implementation of a meaning-making approach, known as the Acquisition Model, to second language instruction. Of particular focus were the concerns and strategies the second language teachers experienced when changing their pedagogical practice from mechanical to meaning making. The main research question, which guided this study, was: "What is the 'lived experience' of L2 teachers as they implement an innovative pedagogy to teach a second language?" The researcher addressed this research question through Max van Manen's (1990) six step phenomenological method, "Researching Lived Experience" and image-based research techniques (i.e., photo elicitation and reflexive photography). In addition, the researcher also created and applied an innovative data collection technique, which she called Collaborative Imagery. Findings from this study generated various implications in the areas of second language education, curricular change, teacher reflection, image-based research, and educational research.
Date: May 2006
Creator: DeLaCruz-Raub, Jeanne Marie
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Pathophysiology and Racial/Ethnic Disparities in the Progression of Metabolic Syndrome

Access: Use of this item is restricted to the UNT Community
Disparities exist in the U.S. between the health status of African American and Hispanic individuals and the health status of non-Hispanic Caucasian individuals across all age groups. Those minority individuals age 55 and over are more likely to suffer from specific health disparities in areas such as diabetes, heart disease, and cancer than their white majority counterparts. Among the most common chronic disorders experienced within this age group are obesity, type II diabetes and cardiovascular disease, all three of which collectively form what has recently become known as metabolic syndrome. As of 2004, metabolic syndrome is diagnosable once criteria are clinically significant for a variety of different risk factors designated by the World Health Organization. However, like many syndromes these criteria are not stable across individuals, and leaves variability between individuals being diagnosed. It has been seen that each of the above mentioned racial/ethnic groups experience the individual risk factors at disproportionate rates, making it plausible that metabolic syndrome could be experienced in distinctly different ways depending upon racial/ethnic background. Using two nationally representative data sets, it is first largely evident that African American and Hispanic individuals are reaching higher peak rates of diabetes and cardiovascular disease much earlier in …
Date: August 2006
Creator: O'Neill, Amy E.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Cross-Cultural Adaptability of Texas Dental Hygienists and Dental Hygiene Students: A Preliminary Study

Access: Use of this item is restricted to the UNT Community
This causal-comparative and correlational study examined cross-cultural adaptability of randomly selected licensed dental hygienists, 1995-2005 graduates, practicing in the state of Texas and first and second-year dental hygiene students attending 5 randomly selected accredited 2 and 4-year dental hygiene schools in the state of Texas. A sample of 289 individuals: 194 enrolled students and 95 licensed dental hygienists, alumni of the 5 schools, completed the 50-item Cross-Cultural Adaptability Inventory (CCAI ®) and a brief demographic survey. The purpose of this study was to determine if statistically significant differences existed among and between licensed dental hygienists and first and second-year dental hygiene students in the state of Texas on a cross-cultural adaptability measure. The study also examined relationships among and between cross-cultural adaptability scores, as measured by the CCAI, and several independent variables. The data were analyzed by using the Statistical Package of Social Sciences (SPSS 12). Eight hypotheses related to group differences and relationships among and between groups and variables were tested. The groups were compared on total CCAI scores using a t-test, and on subscale CCAI scores simultaneously using a descriptive discriminant analysis (DDA). A 3X2 MANOVA was used to compare all groups simultaneously on subscale CCAI scores. The …
Date: August 2006
Creator: Tavoc, Tabitha
Object Type: Thesis or Dissertation
System: The UNT Digital Library

A social capital perspective on IT professionals' work behavior and attitude.

Access: Use of this item is restricted to the UNT Community
Abstract Attracting and developing information technology (IT) professionals is one of the top concerns for companies. Although much research has been conducted about the job behavior and attitudes of IT professionals over the last three decades, findings are inconclusive and contradictory. This suggests that something may be missing in how we examine this phenomenon. Most of this research is drawn from theories of motivation, very little examines the effect of social relationships on IT professionals' behavior and attitude. Yet, social capital theory suggests that job behavior and attitude may be greatly influenced by these relationships. This suggests that IT professionals' social capital warrants empirical examination. The primary research question that this dissertation addresses is how social capital affects IT professionals' work attitude and behavior including job satisfaction, organizational citizenship behavior, job performance and turnover intention. The research model in this dissertation examines the influence of three aspects of social capital on IT professionals' job attitude and work behavior: tie strength, the number of ties and the structural holes. Data were collected from 129 IT professionals from a range of jobs, organizations and industries. Results indicate that tie strength in the organization of an IT professional is positively related to job …
Date: August 2006
Creator: Zhang, Lixuan
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Influence of executive function on medication adherence in neurologically impaired and non-impaired elderly.

Access: Use of this item is restricted to the UNT Community
Medication non-compliance has become one of the most prevalent reasons for hospitalization and doctor's visits by the elderly. As the elderly population is more likely to have decreased cognitive abilities, it is suggested that neuropsychological factors, especially executive function, are more influential in medication non-compliance than once thought. This study looked at executive function performance on a traditional battery of neuropsychological tests, self-report of perceived ability to perform executive function tasks, and the newly developed Pillbox Test, a performance based IADL measure. The Pillbox Test is designed to replicate a type of medication-management specific IADL as a means to asses executive function. Standard executive function measures only tap a portion of executive function, but it is believed that the Pillbox Test incorporates all four theoretical domains of executive function. The multiple measures of executive function performance were compared in three prevalent subgroups of the elderly population (mixed neurological group, cardiac medical-control group, and healthy community-control group). Results found significant differences, where the community-control and cardiac groups outperformed the mixed neurological group on the large majority of executive function tasks. Smaller differences were also noted between the community-control and cardiac groups and between the cardiac and mixed neurological groups. Together, these …
Date: August 2006
Creator: Zartman, Andrea Leigh
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Constraints on Adoption of Innovations: Internet Availability in the Developing World.

Access: Use of this item is restricted to the UNT Community
In a world that is increasingly united in time and distance, I examine why the world is increasingly divided socially, economically, and digitally. Using data for 35 variables from 93 countries, I separate the countries into groups of 31 each by gross domestic product per capita. These groups of developed, lesser developed and least developed countries are used in comparative analysis. Through a review of relevant literature and tests of bivariate correlation, I select eight key variables that are significantly related to information communication technology development and to human development. For this research, adoption of the Internet in the developing world is the innovation of particular interest. Thus, for comparative purposes, I chose Internet Users per 1000 persons per country and the Human Development Index as the dependent variables upon which the independent variables are regressed. Although small in numbers among the least developed countries, I find Internet Users as the most powerful influence on human development for the poorest countries. The research focuses on key obstacles as well as variables of opportunity for Internet usage in developing countries. The greatest obstacles are in fact related to Internet availability and the cost/need ratio for infrastructure expansion. However, innovations for expanded …
Date: December 2006
Creator: Stedman, Joseph B.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Influence of Sediment Exposure and Water Depth on Torpedograss Invasion of Lake Okeechobee, Florida

Access: Use of this item is restricted to the UNT Community
Torpedograss (Panicum repens) was first observed in Lake Okeechobee in the 1970s and appears to have displaced an estimated 6,400 ha of native plants, such as spikerush (Eleocharis cellulosa), where inundation depths are often less than 50 cm. Two series of studies evaluated substrate exposure and water depth influences on torpedograss establishment and competitiveness. Results revealed that fragments remain buoyant for extended periods and so facilitate dispersal. Once anchored to exposed substrate fragments can readily root and establish. Subsequently, torpedograss thrives when subjected to inundations to 75 cm and survives prolonged exposure to depths greater than 1 m. These findings suggest that fluctuating water levels contribute to torpedograss dispersal and colonization patterns and that low water levels increase marsh area susceptible to invasion. The competition study found that spikerush grown in monoculture produces significantly more biomass when continually inundated to shallow depths (10 to 20 cm) than when subjected to drier conditions (-25 cm) or greater inundations (80 cm). In contrast, torpedograss establishes more readily on exposed substrate (-25 to 0 cm) compared to inundate substrates. During the first growing season biomass production increases as substrate exposure interval increases. However, during the second year, established torpedograss produces more biomass when …
Date: December 2006
Creator: Smith, Dian H.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

A Critical Study of Arnold Schoenberg's Chamber Transcription of Gustav Mahler's Das Lied von der Erde

Access: Use of this item is restricted to the UNT Community
Toward the end of his life, from 1908 to 1909, Gustav Mahler (1860-1911) composed Das Lied von der Erde (The song of the earth). This piece is a cycle of six song movements based on seven poems selected from Die chinesische Flötem - Nachdichtungen chinesischer Lyrik (The Chinese flute - free adaptation of Chinese lyric poetry) by Hans Bethge. The Chinese verse was written by Li-Po (numbers 1, 3, 4 and 5), Tchang-Tsi (number 2), and Mong-Kao-Jen and Wang-Wei (combined in number 6). Subsequently, in 1921, Arnold Schoenberg reduced the work to a simple chamber version transcription from Mahler's original massive score for full orchestra, a version completed in 1983 by Rainer Riehn. While the main melodic material in the vocal parts was maintained, the orchestral parts underwent substantial changes. This dissertation explores Mahler's reconfiguration of textual material and the setting of these texts in the orchestral medium. After consulting the various textual editions, I establish misreading and translational differences from the original Chinese through its various Western European incarnations; how and why Mahler chose the Bethge edition; what influenced his specific selection of poetry; and how these poems inform one another and the work as a whole. I also …
Date: August 2006
Creator: Sun, Ai-Kuang
Object Type: Thesis or Dissertation
System: The UNT Digital Library

An Overview and Performance Guide to Manuel Ponce's Sonata III for Solo Guitar

Access: Use of this item is restricted to the UNT Community
Composed in 1927 and dedicated to Segovia, Ponce's Sonata III, one of the staples of the classical guitar repertoire, is the focus of this paper. To put this piece into proper perspective among Ponce's other works, biographical information leading up to the composition of the piece is presented first. Each of the three movements is then analyzed with regard to formal construction as well as harmonic and melodic language. Analysis is an important precursor to actually playing the piece, as Sonata III is a work that departs from Ponce's previous compositional style. The main portion of this paper addresses the preparation and interpretation of Sonata III. The insight gained through initial analysis of the piece is used to arrive at a musically satisfying interpretation of the work. Specific performance suggestions are included. Technical issues are addressed and possible solutions are presented. Alternate fingerings are provided to alleviate some of the common technical challenges the guitarist will encounter. A transcription and discussion of the Segovia revisions are also present. The paper concludes with general suggestions for improving performance that would be applicable to other works for guitar as well. This synthesis of biographical information, analysis, editorial options and performance suggestions, has …
Date: August 2006
Creator: Smith, Jay
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Synthesis and Complexation Studies of Novel Functionalized Crown Ethers and Azacrown Ethers

Access: Use of this item is restricted to the UNT Community
Novel cage-functionalized azacrown ethers, i.e. 51, 52, 53, 55, 57, 61 and 62, which have various crown cavity and different number of nitrogen atoms incorporated, have been prepared. X-ray structures of 53, 55 and 57 have been obtained for the study of the crown topological structure. The complexation properties of crown 51, 52, 57, 61 and 62 have been evaluated via alkali metal picrate extraction, silver picrate extraction and ESI-MS study. The novel cage-fuctionalized azacrown ethers generally exhibit high avidity and selectivity towards Ag+ versus alkali metal ions and some transition metals i.e. Cu2+, Mn2+, Zn2+, Ni2+ and Pb2+. Crown 61 displays significant avidity and selectivity toward K+ in alkali metal picrate extraction experiments vis-à-vis the remaining alkali metal picrates. Three types of ditopic ion-exchange receptors for sodium hydroxide extraction study have been designed. All of the crown ether molecules have proper cavity for selective sodium complexation and have weakly acidic ionizable alcohols for sodium-proton exchange under strongly basic conditions. Crown 80 and 81 were synthesized; key intermediates for the synthesis of crown 82, 83 and 84 have been prepared. The preparation of 99 afforded an unexpected crown 103. The preparation of 109 had been attempted, but could not be …
Date: May 2006
Creator: Huang, Zilin
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Interfacial Studies of Bimetallic Corrosion in Copper/Ruthenium Systems and Silicon Surface Modification with Organic and Organometallic Chemistry

Access: Use of this item is restricted to the UNT Community
To form Cu interconnects, dual-damascene techniques like chemical mechanical planarization (CMP) and post-CMP became inevitable for removing the "overburden" Cu and for planarizing the wafer surface. During the CMP processing, Cu interconnects and barrier metal layers experience different electrochemical interactions depending on the slurry composition, pH, and ohmic contact with adjacent metal layers that would set corrosion process. Ruthenium as a replacement of existing diffusion barrier layer will require extensive investigation to eliminate or control the corrosion process during CMP and post CMP. Bimetallic corrosion process was investigated in the ammonium citrate (a complexing agent of Cu in CMP solutions) using micro test patterns and potentiodynamic measurements. The enhanced bimetallic corrosion of copper observed is due to noble behavior of the ruthenium metal. Cu formed Cu(II)-amine and Cu(II)-citrate complexes in alkaline and acidic solutions and a corrosion mechanism has been proposed. The currently used metallization process (PVD, CVD and ALD) require ultra-high vacuum and are expensive. A novel method of Si surface metallization process is discussed that can be achieved at room temperature and does not require ultra-high vacuum. Ruthenation of Si surface through strong Si-Ru covalent bond formation is demonstrated using different ruthenium carbonyl compounds. RBS analysis accounted for …
Date: August 2006
Creator: Nalla, Praveen Reddy
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Empirical Tests of the Signaling and Monitoring Hypotheses for Initial Public Offerings

Access: Use of this item is restricted to the UNT Community
The research questions investigated are: 1. Are the expected post-issue fractional holdings of the directors and officers, venture capitalists and institutions signals of firm value? 2. Are the expected post-issue fractional holdings of the directors and officers, venture capitalists and institutions signals of underpricing? and 3. Are the directors and officers, venture capitalists and institutions monitors of IPO investments? The signaling theory developed by Grinblatt and Hwang (1989) (GH) and the monitoring theory for IPO investments have been used to develop the hypotheses for this dissertation. Four factors make my methodology unique. These factors are: 1. I apply and test the GH IPO signaling model over a unique data set collected from the IPO prospectuses, proxy statements and annual reports; 2. I disaggregate the expected post-issue holdings of the different groups of pre-issue blockholders and insiders and hypothesizes that these individual groups represents signals of firm value and underpricing; 3. I hypothesize that these groups, in aggregate and separately, monitor IPO investments over the long term; And 4. I develop signaling and monitoring hypotheses to make predictions at the two stages of the IPO. The results show that firm value is positively related to the level of underpricing, at a …
Date: May 2006
Creator: Gordon, Sean Anthony Garnet
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Synthesis and characterization of quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers and reaction chemistry of the diphosphine ligand 2,3-bis(diphenylphosphino)-N-p-tolylmaleimide (bmi) at triosmium carbonyl clusters.

Access: Use of this item is restricted to the UNT Community
Quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers have been synthesized as possible specific metal host systems. The synthesis and characterization of quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers have been described. The characterization of these host systems have been fully achieved in solution by using various techniques such as IR, 1H NMR, and 13C NMR spectroscopic methods, high-resolution mass spectrometry (HRMS), elemental microanalysis, and X-ray crystallographic analysis in case of one quinoxaline-functionalized, cage-annulated oxacrown ether compound. The synthesis of the diphosphine ligand 2,3-bis(diphenylphosphino)-N-p-tolylmaleimide (bmi) is described. The substitution of the MeCN ligands in the activated cluster 1,2-Os3(CO)10(MeCN)2 by the diphosphine ligand bmi proceeds rapidly at room temperature to furnish a mixture of bridging and chelating Os3(CO)10(bmi) isomers and the ortho-metalated product HOs3(CO)9[μ-(PPh2)C=C{PPh(C6H4)}C(O)N(tolyl-p)C(O)]. Thermolysis of the bridging isomer 1,2-Os3(CO)10(bmi) under mild conditions gives the chelating isomer 1,1-Os3(CO)10(bmi), whose molecular structure has been determined by X-ray crystallography. The kinetics for the ligand isomerization have been investigated by UV-vis and 1H NMR spectroscopy in toluene solution over the temperature range of 318-348 K. On the basis of kinetic data conducted in the presence of added CO and the Eyring activation parameters, a non-dissociative phosphine migration across one of the Os-Os bonds is proposed. Orthometalation of …
Date: December 2006
Creator: Poola, Bhaskar
Object Type: Thesis or Dissertation
System: The UNT Digital Library