M.S. / Chemistry / Resonance Raman spectra of the complex of FeIII-ethylenediamine-tetraacetate with hydrogen peroxide have been obtained in the region of the peroxidic O-O stretching vibration that occurs at 815 cm [superscript -1] in frozen solution. When the complex was prepared from nearly neat, mixed-isotope hydrogen peroxide, H216O18O, a single O-O vibration was observed at 794 cm [superscript -1]. This observation establishes that the two oxygen atoms of the bound peroxide are equivalent and that the peroxide is ligated in an η2 side-on configuration in this mononuclear complex. The absence of any shift in υ(O-O) when the complex was prepared in D2O solvent provides further support for the Fe-OO geometry and rules out the alternative η1 end-on Fe-OOH configuration. In contrast, υ(O-O) of free hydrogen peroxide in the frozen state occurs at 877 cm [superscript -1] in H2Oand at 879 cm [superscript -1] in D2O. The 2- cm [superscript -1] upshift in D2O is similar to that observed previously with oxyhemerythrin and appears to be characteristic of a hydrogen-bonded or protonated peroxide species.

No description available.

The study presented in this thesis was aimed to gain the fundamental knowledge regarding the mechanism of H2S measurement in sera by using carbon nanotubes (CNT) and fluorescence response. Characterization techniques such as Raman spectroscopy, X-ray absorption spectroscopy (XAS) and confocal laser scanning microscopy (CLSM) were employed to achieve this goal. The model system used for this study was composed of H2S, distilled water, two major serum proteins (albumin and globulin), serum, hemoglobin, and CNT. The results of this study showed that: (1) Two major serum proteins (albumin and globulin) are physically adsorbed on the sidewall of the CNTs; while H2S is adsorbed on the defect site of the CNTs. (2) Presence of the proteins on the CNTs did not affect the CNTs adsorption of H2S. (3) Using CLSM with the incident wavelength of 514 nm and the emission wavelength of 530 to 580 nm to acquire the fluorescence response of the H2S adsorbed on the CNTs is a reliable approach to measure H2S in sera. (4) Single-wall carbon nanotubes (SWNTs) outperform multi-wall carbon nanotubes (MWNTs) in measurement sensitivity. (5) Presence of hemoglobin in a H2S solution did not affect the measurement of H2S with CNTs and CLMS. The study described in this thesis has provided new knowledge of the interaction behaviors of CNTs with H2S and major proteins in sera along with the mechanism which governs these behaviors. Such knowledge is very useful to further advance the CNT approach to sensing H2S in sera and water solution and to further extend the approach to sensing H2S in other mammalian tissues such as blood.

The study presented in this thesis was aimed to gain the fundamental knowledge regarding the mechanism of H2S measurement in sera by using carbon nanotubes (CNT) and fluorescence response. Characterization techniques such as Raman spectroscopy, X-ray absorption spectroscopy (XAS) and confocal laser scanning microscopy (CLSM) were employed to achieve this goal. The model system used for this study was composed of H2S, distilled water, two major serum proteins (albumin and globulin), serum, hemoglobin, and CNT. The results of this study showed that: (1) Two major serum proteins (albumin and globulin) are physically adsorbed on the sidewall of the CNTs; while H2S is adsorbed on the defect site of the CNTs. (2) Presence of the proteins on the CNTs did not affect the CNTs adsorption of H2S. (3) Using CLSM with the incident wavelength of 514 nm and the emission wavelength of 530 to 580 nm to acquire the fluorescence response of the H2S adsorbed on the CNTs is a reliable approach to measure H2S in sera. (4) Single-wall carbon nanotubes (SWNTs) outperform multi-wall carbon nanotubes (MWNTs) in measurement sensitivity. (5) Presence of hemoglobin in a H2S solution did not affect the measurement of H2S with CNTs and CLMS. The study described in this thesis has provided new knowledge of the interaction behaviors of CNTs with H2S and major proteins in sera along with the mechanism which governs these behaviors. Such knowledge is very useful to further advance the CNT approach to sensing H2S in sera and water solution and to further extend the approach to sensing H2S in other mammalian tissues such as blood.

No description available.

No description available.

Thermal barrier coatings (TBCs) have become an important part of turbine technology by providing thermal protection to the underlying metallic components. These coatings are typically made from a zirconia-based ceramics which have a low thermal conductivity and thermal expansion coefficients similar to those of the superalloys. Early failure in these coatings is most often due to foreign object damage and erosion resulting in delamination and spallation. To protect against these types of failure, new materials with increased toughness are needed. There are two main toughening mechanisms in ceramics: transformation toughening, which is limited to low temperature applications and ferroelastic toughening which is accessible at all temperatures. Ferroelastic toughening occurs when the c-axis of the tetragonal grain undergoes reorientation under the application of an external stress. In this study, ferroelastic toughening is examined by Raman spectroscopy. It is shown that by using polarized confocal Raman spectroscopy one can not only observed the ferroelastic process, but also measure the parameters that control the increase in toughness observed. Ferroelastic toughening was observed in two ways in the 18mol% ceria stabilized zirconia (18CSZ) samples studied here. Samples were either exposed to indentation damage or uniaxial loading. In both of these cases maps of the ceramic surface were taken using Raman spectroscopy following loading and the relative intensities of the tetragonal peaks were analyzed. The resulting intensity profiles were used to monitor the reorientation of domains corresponding to ferroelastic toughening. Changes in domain orientation were observed that corresponded to the reorientation of domains along cracks as well as on a larger scale along those cracks. Domain reorientation was also observed under uniaxial loading and the stresses required for domain formation and movement were measured.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 168-177).

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 114-120). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.