States

Syntheses, X-ray Diffraction Structures, and Kinetics on New Formamidinate-Substituted Triosmium Clusters (open access)

Syntheses, X-ray Diffraction Structures, and Kinetics on New Formamidinate-Substituted Triosmium Clusters

The reaction between the formamidine ligand PriN=CHNHPri and the activated cluster Os3(CO)10(MeCN)2 has been studied. A rapid reaction is observed at room temperature, yielding the hydride clusters HOs3(CO)9[μ-OCNPriC(H)NPri] and HOs3(CO)10[μ-NPriC(H)NPri] as the principal products. The spectroscopic data and X-ray diffraction structures of those formamidinate-substituted clusters will be present. The thermal reactivity of the clusters has been investigated, with the face-capped cluster HOs3(CO)9[μ-NPriC(H)NPri] found as the sole observable product. The relationship between these three clusters has been established by kinetic studies, the results of which will be discussed.
Date: December 2010
Creator: Yang, Li
System: The UNT Digital Library
Synthetic, Mechanistic, and Structural Studies of Polynuclear Metal Clusters and Hydrazido-Substituted Tantalum(V) Compounds (open access)

Synthetic, Mechanistic, and Structural Studies of Polynuclear Metal Clusters and Hydrazido-Substituted Tantalum(V) Compounds

A combined experimental and computational study on the reversible ortho-metalation exhibited by the triosmium cluster Os3(CO)10(dppm) (dppm = 1,1-bis(diphenylphosphino)methane is reported. The conversion of nonacarbonyl cluster HOs3(CO)9[-PhP(C6H4)CH2PPh2] to Os3(CO)10(dppm) is independent of added CO and exhibits a significant inverse equilibrium isotope effect (EIE). Reductive coupling of the C-H bond in HOs3(CO)9[-PhP(C6H4)CH2PPh2] leads to the formation of agostic C-H and two distinct aryl-π species prior to the rate-limiting formation of the unsaturated cluster Os3(CO)9(dppm). Heating the unsaturated dimer H2Re2(CO)8 with Cp*Rh(CO)2 (Cp* = 1,2,3,4,5-pentamethylcyclopentadiene) at elevated temperature affords the new trimetallic clusters H2RhRe2Cp*(CO)9 and HRh2ReCp*2(CO)6, and the spiked-triangular cluster HRhRe3Cp*(CO)14. H2Re2(CO)8 reacts with Cp*2Rh2(CO)2 under identical conditions to furnish H2RhRe2Cp*(CO)9 and HRh2ReCp*2(CO)6 as the principal products, in addition to the tetrahedral cluster H2Rh2Re2Cp*2(CO)8. H2RhRe2Cp*(CO)9 undergoes facile fragmentation in the presence of halogenated solvents and the thiols RSH (where R = H, C6H4Me-p) to afford the structurally characterized products Cp*Rh(-Cl)3Re(CO)3, S2Rh3Cp*(CO)4, Cp*Rh(-Cl)(-SC6H4Me-p)2Re(CO)3, and Cp*Rh(-SC6H4Me-p)3Re(CO)3. The new hydrazido-substituted compounds TaCl(NMe2)3[N(TMS)NMe2] (TMS = tetramethylsilyl) and Ta(NMe2)4[N(TMS)NMe2] have been synthesized and their structures established by X-ray crystallography. The latter product represents the first structurally characterized octahedral tantalum(V) complex containing a single hydrazido(I) ligand in an all-nitrogen coordinated environment about the metal center. The fluxional properties …
Date: December 2010
Creator: Huang, Shih-Huang
System: The UNT Digital Library
Thermal Identification of Clandestine Burials: A Signature Analysis and Image Classification Approach (open access)

Thermal Identification of Clandestine Burials: A Signature Analysis and Image Classification Approach

Clandestine burials, the interred human remains of forensic interest, are generally small features located in isolated environments. Typical ground searches can be both time-consuming and dangerous. Thermal remote sensing has been recognized for some time as a possible search strategy for such burials that are in relatively open areas; however, there is a paucity of published research with respect to this application. This project involved image manipulation, the analyses of signatures for "graves" of various depths when compared to an undisturbed background, and the use of image classification techniques to tease out these features. This research demonstrates a relationship between the depth of burial disturbance and the resultant signature. Further, image classification techniques, especially object-oriented algorithms, can be successfully applied to single band thermal imagery. These findings may ultimately decrease burial search times for law enforcement and increase the likelihood of locating clandestine graves.
Date: December 2010
Creator: Servello, John A.
System: The UNT Digital Library
User Acceptance of North Central Texas Fusion Center System by Law Enforcement Officers (open access)

User Acceptance of North Central Texas Fusion Center System by Law Enforcement Officers

The September 11 terrorist attacks pointed out the lack of information sharing between law enforcement agencies as a potential threat to sound law enforcement in the United States. Therefore, many law enforcement agencies as well as the federal government have been initiating information sharing systems among law enforcement agencies to eradicate the information sharing problem. One of the systems established by Homeland Security is the North Central Texas Fusion Center (NCTFC). This study evaluates the NCTFC by utilizing user acceptance methodology. The unified theory of acceptance and the use of technology is used as a theoretical framework for this study. Within the study, user acceptance literature is examined and various models and theories are discussed. Furthermore, a brief information regarding the intelligence work done by law enforcement agencies are explained. In addition to the NCTFC, several major law enforcement information systems are introduced. The data for this study comes from the users of the NCTFC across the north central Texas region. Surveys and interviews are used to triangulate data. It is found in this study that performance expectancy and effort expectancy are important indicators of system use. Furthermore, outreach and needs assessment are important factors in establishing systems. The results …
Date: December 2010
Creator: Odabasi, Mehmet
System: The UNT Digital Library
The Variable use of ne in Negative Structures: An Apparent-Time Variationist Study of Synchronous Electronic French Discourse (open access)

The Variable use of ne in Negative Structures: An Apparent-Time Variationist Study of Synchronous Electronic French Discourse

This study of the variable use of ne in synchronous electronic French discourse follows the methodological guidelines and the theoretical framework proposed and subsequently elaborated by Labov for analyzing variable features of language. This thesis provides a quantitative variable rule (i.e., VARBRUL) analysis including age as a factor group (i.e., independent variable), thereby making a new contribution to this area of inquiry. The data (50,000 words from the vingtaine 'twentysomething' channel and 50,000 words from the cinquantaine 'fiftysomething' channel) are a subset of 100,000 words from a corpus of one million words collected in 2008 by the thesis director from the public chat server EuropNet. This study aims to answer the following overarching question: To what extent does age-compared to other factors-influence the variable use of ne in verbal negation in synchronous electronic French discourse? In order to answer this question, and possibly others, the VARBRUL analysis will include age, subject (e.g., noun vs. pronoun), type of second negative particle (e.g., pas 'not', jamais 'never', personne 'no one'/'nobody', and so forth), as well as verbal mood/tense.
Date: December 2010
Creator: Gould, Rebecca J.
System: The UNT Digital Library
White Creole Women in the British West Indies: From Stereotype to Caricature (open access)

White Creole Women in the British West Indies: From Stereotype to Caricature

Many researchers of gender studies and colonial history ignore the lives of European women in the British West Indies. The scarcity of written information combined with preconceived notions about the character of the women inhabiting the islands make this the "final frontier" in colonial studies on women. Over the long eighteenth century, travel literature by men reduced creole white women to a stereotype that endured in literature and visual representations. The writings of female authors, who also visited the plantation islands, display their opinions on the creole white women through their letters, diaries and journals. Male authors were preoccupied with the sexual morality of the women, whereas the female authors focus on the temperate lifestyles of the local females. The popular perceptions of the creole white women seen in periodicals, literature, and caricatures in Britain seem to follow this trend, taking for their sources the travel histories.
Date: December 2010
Creator: Northrop, Chloe Aubra
System: The UNT Digital Library