Grinding/polishing and indentation induced residual stresses were measured by confocal Cr³⁺ fluorescence microscopy with high spatial resolution (~2 μm),obtaining local stress variation information rather than the mean stress averaged over a large sampling volume as is measured by other techniques. Due to the translucency of alumina materials, a substantial portion of the fluorescence signal comes from beneath the surface of the specimen. A probe response function (PRF) was developed taking account of microscope resolution, refraction, absorption and scattering, to quantitatively describe where the collected signal came from. It described the fluorescence intensity variations against defocus distance very well for a range of materials including sapphire, ruby, polycrystalline alumina and AI₂O₃/SiC nanocomposites. Large variations in the residual stresses on ground and polished surfaces were observed, owing to the surface fracture and pullouts. The broad peaks and narrow peaks separated from the spectra collected near the ground/polished surfaces physically represented the two distinct regions in the ground region: a plastically deformed surface layer and the elastically deformed material underneath. A model for the residual stress field taking into account the pullout was proposed using an array of virtual dislocations. The model agreed with the experimental results well when the PRF was included. Tensile stresses were detected on the ground surfaces of polycrystalline aluminas and 2 vol.% SiC nanocomposite, but not on the polished surfaces of polycrystalline aluminas or ground surfaces of 5 and 10 vol.% SiC nanocomposites. This was explained in terms of difference in the amount of pullouts on the surfaces. The depth of deformation was deeper in the ground polycrystalline alumina compared to the polished condition; the depth of deformation in alumina and the AI₂O>sub>3</sub>/SiC nanocomposites were similar (~1 μm) while the compressive stresses in the nanocomposites were greater owing to the reduction in pullout. The main difference between ground alumina and AI₂O₃/SiC nanocomposites was the brittle fracture behavior rather than the plastic deformation. Line scans and area mapping were carried out on 1 kg loaded Vickers indentations of alumina-based ceramics. Tensile stresses were found at the tips of radial cracks and lateral cracks and compressive stresses were found around the indent impression. The line scan results in the elastic regions agreed qualitatively with Yoffe's model and the quantitative discrepancy was attributed mainly to the cracking that relaxed the stresses. The differences in residual stresses between alumina and AI₂O₃/SiC nanocomposites were small if measured with high spatial resolution but it would be exaggerated with lower resolution.

Dynamical heterogeneity (DH) has been observed in many systems approaching the glass or jamming transition. Whether DH has a structural origin is under heated debate. To provide a deeper understanding, in this thesis I investigate the microscopic dynamics in weakly attractive colloidal systems by confocal fluorescence microscopy. The van Hove density-density correlation function is applied to our systems. Separable fast and slow populations emerge in the self part (svH), while the distinct part shows a strong signature of DH close to the gel transition. At intermediate time, svH shows a purely exponential tail, mainly arising from the fast population. I show that this broad tail is a direct consequence of the occurrence of rare large jumps that are statistically distributed. The slow population tends to form a space-spanning backbone, and its mean squared displacement close to the gel transition exhibits a plateau, whose height is consistent with the range of attraction, suggesting a bonding mechanism for the dynamical arrest. I further examine various quantities characterizing local structure and local dynamics and a strong correlation is identified between them. Subsequently, I develop order parameters for quantifying amorphous structure and apply them to our systems. I find that attractive colloidal systems exhibit higher order under higher attraction tension, while hard spheres become more ordered under higher compression. Finally, I investigate the effect of the range of attraction on the structure and dynamics of attractive colloidal systems. I observe that the system with shorter range of attraction forms a denser and more heterogeneous structure. Meanwhile, I observe an even stronger dynamical heterogeneity. These observations provide further evidence of a connection between structural heterogeneity and dynamical heterogeneity in these systems, providing guidance for a theoretical description of the dynamical arrest as well as the relaxation mechanisms upon gelation and its relation to solidification in glasses. / In order to do all of this, I first implemented full 3D subpixel resolution localization of particles and improved particle tracking algorithms tailored for the sorts of heterogenous dynamics these systems exhibit, that otherwise confounds existing methods such that the very relaxation mechanisms would be missed. This allows us to obtain unprecedented precision in positions of all of the particles and complete tracking, both of which are essential for correctly determining system properties that depend on measured particle dynamics.

The Barzilai-Borwein (BB) method for unconstrained optimization has attracted attention for its "chaotic" behaviour and fast convergence on image deconvolution problems. However, images with large areas of darkness, such as those often found in astronomy or microscopy, have been shown to benefit from approaches which impose a nonnegativity constraint on the pixel values. We present a new adaptation of the BB method which enforces a nonnegativity constraint by projecting the solution onto the feasible set, but allows for infeasible iterates between projections. We show that this approach results in faster convergence than the basic Projected Barzilai-Borwein (PBB) method, while achieving better quality images than the unconstrained BB method. We find that the new method also performs comparably to the Gradient Projection-Conjugate Gradient (GPCG) method, and in most test cases achieves a lower restoration error, despite being a much simpler algorithm.

This thesis describes the development of novel fluorescent and photocaged lipids, and their application as tools to probe the morphological effects of ceramide (Cer)-mediated membrane reorganization in supported lipid bilayers. Cer is a sphingolipid found in eukaryotic cells that plays a key role in regulating biological processes such as apoptosis, cell-to-cell communication, differentiation and some types of pathogenesis. Sphingolipid and cholesterol-rich lipid rafts in the plasma membrane are thought to be the point of origin for many of this lipid second messenger’s effects. Cer is formed in the exoplasmic leaflet of the plasma membrane via the enzymatic hydrolysis of sphingomyelin. The compositional complexity of biological membranes has prompted the adoption of simpler model systems to study the effects of Cer generation. When it is directly incorporated into model membranes, Cer segregates into highly ordered domains with physical properties that are distinct from those of the surrounding fluid environments. However, enzymatic generation of Cer induces complex and dynamic membrane heterogeneity that is difficult to interpret and reconcile with its direct incorporation. Here I describe the synthesis of 4-nitrobenzo-2-oxa-1,3-diazol-7-yl (NBD)-labelled cholesterol (Chol) and Cer analogs, and their use as probes in model membranes exhibiting liquid-disordered (Ld) and liquid-ordered (Lo) phase coexistence. The Chol probes reproduce the modest enrichment of Chol in Lo membrane domains as well as the Cer-induced displacement of cholesterol. One of the NBD Chol probes is used to provide direct visualization of Chol redistribution during enzymatic Cer generation, and assists in identifying new features as Cer-rich regions. The NBD-labelled Cer quantifies membrane order using orientational order parameter measurements derived from polarized total internal reflection fluorescence microscopy (pTIRFM) images. The probe reports on changes in membrane order upon enzymatic generation of Cer, and indicates a significant increase in the molecular order of Ld membrane regions that is consistent with the redistribution of Chol into these areas. The probe also identifies de novo Cer-rich domains as areas of particularly high molecular order. In the final project area, 6-Bromo-7-hydroxycoumarin-4-ylmethyl (Bhc)-caged Cers are shown to release Cer rapidly and efficiently upon irradiation with near-visible UV light. The caged lipids are then incorporated into supported membranes and photolyzed to release Cer with a high degree of spatial and temporal control. Controlled Cer generation is then used to drive protein-ganglioside clustering in lipid bilayers.

The object of this thesis is to present two novel applications of Spatiotemporal Image Correlation Spectroscopy (STICS) to biological systems. STICS is a technique which uses the correlations in pixel intensity fluctuations of an image time series, captured under fluorescence microscopy, to measure the speed and direction of a flowing population of fluorescently labeled molecules. The method was first applied to measure the dynamics of transport vesicles inside growing pollen tubes of lily flowers. The measured vector maps allowed to confirm the presence of actin filaments along the periphery of the tubes, as well as the presence of a reverse-fountain pattern in the apical region. In a second set of experiments, STICS was used to measure the retrograde flow of filamentous actin in migrating chick DRG neuronal growth cones. These results serve as proof of principle that STICS can be used to probe the response of the growth cone cytoskeleton to external chemical cues.

Thesis (Ph. D. in Chemistry)--Vanderbilt University, Dec. 2008. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--University of Toledo, 2008. / Typescript. "Submitted as partial fulfillments of the requirements for The Master of Science in Pharmaceutical Sciences in Pharmacology and Toxicology." "A thesis entitled"--at head of title. Bibliography: leaves 47-49.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 110-113).

Thesis (Ph. D.)--Duke University, 2007. / Includes bibliographical references.

Thesis (M.S.)--Ohio University, June, 2005. / Title from PDF t.p. Includes bibliographical references (p. 77-88)