In this study, we have successfully developed an acoustic modulation microscopy that is based on a laser scanning confocal microscopy and operates in the range of a few tens of kilohertz. The induced submicron oscillation is detected through the combination of differential confocal microscopy and lock-in circuit. In this way, the mechanical properties, such as elasticity and stiffness, can be mapped in a two-dimensional way rapidly.

Abstract The present thesis focused on the synthesis and phase transformation of tohdite and alumina via static compression of gels at high temperature-pressures and dynamic laser ablation condensation of metal target under oxygen background gas. In part I, hydrous Al2O3-TiO2 (78:22 in molar ratio) gel was fired at various PT conditions using a piston-cylinder apparatus and identified by XRD, FTIR, optical microscopy and electron microscopy. Below 675oC, the sample remained amorphous at ambient pressure, yet transformed at 1.5 kbar to Ti-doped tohdite, which is elongated along the crystallographic c-axis, with well-developed (0001) base and {10 0} faces. Tohdite has a significant water/hydroxy content and is therefore susceptible to pore coalescence parallel to the basal layer upon electron dosage. Tohdite also contains Ti4+ up to 3 at.%, which replaces Al3+ in tetrahedral and/or octahedral sites to form superstructures and defect microstructures. In contrast, a higher T-P condition (above 675oC and 8 kbar) caused the formation of more stable Ti-doped corundum, which is hexagonal-rhombohedral crystal form and in epitaxial association with rutile nuclei. Ti-doped tohdite and corundum shed light on a sol-gel route for their occurrence in peraluminous metamorphic rock. The nanoporous and nanodelaminated tohdite may have potential catalytic applications (Part I). In part II, amorphous Al2O3 nanocondensates were synthesized via very energetic Nd-YAG laser pulse irradiation of oxygen-purged Al target for a very rapid heating/cooling effect. The nanocondensates above a critical diameter of 20 nm were phase separated as

The way in which the myocardium responds to its mechanical environment must be understood in order to develop reasonable treatments for congestive heart failure. The first step toward this understanding is to characterize and quantify the cardiac microstructure in healthy and diseased hearts. Myocardium has a laminar architecture made up of myolaminae, which are sheets of myocytes surrounded by a collagen weave. By enhancing the contrast between the myocytes and the surrounding collagen, the myocardium can be investigated and its laminar structure can be quantified. Many of the techniques that have been used to view the microstructure of the heart require the use of toxic or caustic chemicals for fixation or staining. An efficient imaging method that uses polarization microscopy and enhances the contrast between the collagen and myocytes while minimizing the use of harmful chemicals was developed in this research. Collagen is birefringent; therefore its visibility should be enhanced through polarization microscopy and image processing. The sheet angles were viewed directly by cutting slices of a rat septum perpendicular to the fiber angle. Images of different polarization combinations were taken and a region of interest was selected on the sample. Image processing techniques were used to reduce the intensity variation on the images and account for the variable gain of the camera. The contrast between the collagen and myocytes was enhanced by comparing adjusted images to the background and looking at a single image this comparison produced. Although the contrast was enhanced, the embedding media reduced the collagen signal and the enhancement was not as striking as expected.

Three-dimensional (3D) structural determination of biological macromolecules is not only critical to understanding their mechanisms, but also has practical applications. Combining the high resolution imaging of transmission electron microscopy (TEM) and efficient computer processing, protein structures in solution or in two-dimensional (2D) crystals can be determined. The lipid monolayer technique uses the high affinity binding of 6His-tagged proteins to a Ni-nitrilotriacetic (NTA) lipid to create high local protein concentrations, which facilitates 2D crystal formation. In this study, several proteins have been crystallized using this technique, including the SARS virus Nsp15 endonuclease and the human Toll-like receptor (TLR) 3 extracellular domain (ECD). Single particle analysis can determine protein structures in solution without the need for crystals. 3D structures of several protein complexes had been solved by the single particle method, including IniA from Mycobacterium tuberculosis, Nsp15 and TLR3 ECD. Determining the structures of these proteins is an important step toward understanding pathogenic microbes and our immune system.

In giant magnetoresistance (GMR) or tunneling magnetoresistance (TMR) materials, the transport properties rely on the related spin configurations, i.e., the parallel spin configuration in both magnetic layers is responsible for the lower resistivity state while the antiparallel spin configuration between them exhibit the higher resistivity state. However, the magnetic materials in realistic do not align completely in one direction; they exhibit magnetic domains to reduce the dipolar interaction instead. It is thus crucial to investigate in detailed about how the magnetic domain evolution influences the magnetoresistance in GMR or TMR materials. So, Photoemission Electron Microscopy (PEEM) and Kerr microscope are very good tools for us to study the magnetic domain in local area. The in-situ preparation Mn/Ag wedge/Fe(100) ultrathin films are measured by Auger electron spectroscopy (AES), low energy electron diffraction (LEED), medium energy electron diffraction (MEED), and photoemission electron microscope (PEEM) in an ultrahigh vacuum chamber. The preparation Ti/Fe/Ti/SiO2/Si(100) thin films are performed in an ultrahigh vacuum chamber and then are measured by Kerr Microscopy in air. By observing the evolution of magnetic domain, we can know more the detailed information on magnetism microscopically and the correlation between the magnetic properties and electric transport properties.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 127-134).

Thesis (Ph. D.)--Lehigh University, 2001. / Includes bibliographical references and vita.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 124-130). Available also in a digital version from Dissertation Abstracts.

Thesis (doctoral)--Rupertus Carola University, 2001. / Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.