Metal-on-metal (MM) bearings have been considered as an alternative to conventional metal-on-polyethylene (MPE) bearings because of their lower volumetric wear, but concern exists due to potential metal hypersensitivity. Metal hypersensitivity reactions have been thought to be T cell-mediated delayed type hypersensitivity (DTH) reaction. However some of the MM periprosthetic tissues show the presence of B- and plasma cells, as well as massive fibrin exudation, which are not characteristic of a DTH reaction. Therefore, the exact nature of the hypersensitivity reaction(s) MM implants remains unclear. The present study aimed to compare the phenotypes of lymphocytes from the peripheral blood and synovial fluid of patients with failed MM and MPE implants, and from volunteers with no implant (peripheral blood only). Results in peripheral blood showed differences in the T-cell populations depending on the implant type. This included differences in the proportions of T-helper and T-cytotoxic cells, and T-cells expressing IFN-g. Results in synovial fluid showed a significant difference between MM and MPE groups for the B-cells. Both groups depicted a predominance of T-cell lymphocytes in synovial fluid and overall larger proportions of memory cells than in peripheral blood, but group sizes were rather small. Overall, T-cell cytokine expression (analyzed in peripheral blood only because of the limited number of synovial fluid samples) did not exhibit characteristics of a DTH reaction and the proportions of memory lymphocytes did not indicate activation of a specific subset in the MM group. Nevertheless, group sizes still remain to be increased.

none

This dissertation concerns the use of bicyclic guanidinate ligands to prepare new dimetal paddlewheel compounds. Specifically, Ru_2^6+, Re_2^6+, Re_2^7+, and Os_2^7+ compounds will be examined to observe any changes brought about by using bicyclic guanidinate ligands with varying ring sizes. In the Ru_2^6+ compounds, different ligand ring sizes cause a change in the electronic configuration and magnetic properties. Bicyclic guanidinate ligands allow the preparation of Re_2^7+ compounds from Re_2^6+ compounds, both of which are examined structurally and electrochemically. [Os2(hpp)4]^+ is examined to improve upon earlier studies, yielding a model of the g-tensor components with respect to the compound structure. An additional project included in the dissertation involves the study of an asymmetric trinickel extended metal atom chain. The structural effects of the asymmetry are examined to help elucidate the magnetic behavior that differs significantly from symmetric trinickel extended metal atom chains.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 144-149).

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 185-195).

Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, 2003. / Word processed copy. Summary in English. Includes bibliographical references (leaves 99-105). Also available online.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 99-107).

The electron density function of molecular systems supplies a package of information. Quantum mechanical methods of producing and analyzing this function have been significantly improved during the past few years. The advent of accurate pseudopotentials and corresponding basis sets for Kohn-Sham density functional and for post-Hartree-Fock electron-correlated approaches have enabled the inclusion of scalar relativistic and spin-orbit coupling effects as well as electron correlation effects into the electron density function. The unpacking of the information embedded in such a function via the quantum theory of atoms in molecules (QTAIM) became possible by utilizing the very new subshell fitting method of reconstructing the density distribution of core electrons that had been replaced by the pseudopotentials. These theoretical advances were applied in this thesis to characterize and explore the topological features of metal-metal bonding as one of the fundamental types of bonds formed between two elements. Group 11 and 12 transition metals which include gold and mercury as the most relativistic elements were the main focus of this work. Mono and poly-nuclear compounds (with up to 4 metal atoms) in both pure metal clusters and chloro-complexes were studied by ab initio MØller-Plesset perturbation calculations followed by QTAIM analysis on the relaxed density. Some of these chloro-complexes of copper, gold, zinc and cadmium metals were identified in the gas phase by mass spectrometric experiments. The general formulas of the set of molecules studied in group 11 were : M2, MCl, MCl+, MCl2, MCl2+, M2Cl+, M2Cl2^(s+), M2Cl3+, M3Cl2+, M3Cl3+, M3Cl5+, M4Cl5+ and M4Cl7+ and in group 12 were : M2, MCl, MCl+, MCl2, M2Cl3+, M3Cl5+, M4Cl7+ and M2^(s+). The topological features of metal-metal bonding were calculated along with atomic properties for each individual local minimum isomer found. The comparison of the metal-metal bonding within the complexes and with the dimers revealed new features of metal-metal bonding in 3d, 4d and 5d transition metal elements of groups 11 and 12. With the aid of strong correlation between bond dissociation energy and electron density at the location of the bond critical points found in the case of dimers, the strength of the metal-metal bonding in the complexes was estimated. The electron density’s basin properties calculated accurately for all the clusters and their isomers in this thesis provided more insight also into the nature of M-Cl bondings in the group 11 and 12 chloride clusters. Ultimately the bonding information was used to predict the viability of these clusters in the gas phase. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.