Thesis (doctoral)--Lunds universitet, Malmö, 1990. / Extra t.p. wih thesis statement inserted. Includes bibliographical references (p. 156-170).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Thesis (doctoral)--Lunds universitet, Malmö, 1990. / Extra t.p. wih thesis statement inserted. Bibliography: p. 156-170.

The mechanical properties of ion implanted ceramics are primarily a function of the radiation damage produced by the implantation process. For crystalline ceramics this damage is chiefly nuclear displacements, though for glasses electronic effects have also been observed. In this study a number of single crystal and polycrystalline ceramics and a soda-lime-silica glass have been implanted with a range of ions in the energy range 90keV to 400keV and the changes in mechanical properties produced have been followed using hardness, indentation fracture and scratch testing. The damage structures which remain after implantation will control both the indentation hardness and surface fracture properties of cetamics. Changing the temperature of the substrate during implantation (in the range. 150K to 760K) has been found to alter this damage state and hence produce changes in the measured mechanical properties. In this temperature range, the effects of damage annealing at low doses were found to be minor for sapphire although for MgO damage annealing was found to result in a eduction of the radiation-induced hardening above 473K. The surface softening and stress relief accompanying amorphisation at higher doses was found to be strongly temperature dependent. Thus, the recrystallisation of amorphous material is important in determining the final mechanical properties of the implanted specimens. The tribological properties of the implanted ceramics were investigated using single pass scratch tests. Friction coefficients were found to increase with dose up to the onset of amorphisation, even when visible scratch tracks were produced. This increse is due to changes in adhesion between the slider and the flat induced by ion implantation. The reasons for these changes are as of yet unclear, though a possible explanation could be the removal of surface adsorbates which has been observed for MgO. Similar mechanical and tribological property changes observed for the polycrystalline ceramics as for the single crystal systems, but some extra effects were observed.

This research sought to integrate measurement and prediction of surface macrotexture for use in pavement management systems. This was achieved through two experiments, the first modeled the behavior of a binder-rich stone matrix asphalt when subjected to traffic loading using a heavy vehicle simulator to report the effect on pavement macrotexture. The second experiment compared high-speed macrotexture measurement devices on a variety of surfaces and under various operating conditions. The change in macrotexture due to traffic loading showed that as the cumulative load increased, the macrotexture decreased due to bleeding on the pavement's surface. A regression model determined that, on average, the macrotexture's root mean square (RMS) decreased 0.14 mm per million equivalent single axle load applied. A comparison of RMS and mean profile depth (MPD) outputs indicated that RMS was more sensitive to changes in macrotexture due to bleeding. In comparing devices, pairwise device agreement was evaluated using a Limits of Agreement. The results demonstrate good repeatability for each of the devices tested. The agreement analysis showed that not all high-speed devices can be used interchangeably for all pavement surfaces. Data acquisition speed was found to be a factor in macrotexture parameter calculation for two of the devices. The effect of speed was found to be worse on randomly textured surfaces than on transversely textured surfaces. / Master of Science / This thesis sought to integrate the collection and prediction of a pavement surface property known as macrotexture for use in the management of pavement networks. This was achieved through two experiments, the first of which modeled the behavior of asphalt concrete with a higher than typical asphalt content when subjected to simulated traffic to determine the effect on pavement macrotexture. The second experiment compared five high-speed macrotexture measurement devices on a variety of pavement surface types and under various operating conditions. The change in macrotexture due to traffic loading showed that as the cumulative traffic increased, the macrotexture decreased due to the asphalt coming out on the surface, referred to as bleeding. For the comparison of measurement devices data were processed using current industry standards. The results demonstrate good repeatability for each of the devices tested. The analysis also showed that not all high-speed devices can be used interchangeably for all pavement surface types. Vehicle speed was found to be a factor for two of the devices. The effect of speed was found to vary by surface type. Finally, vehicle acceleration was shown to influence the parameters produced by one of the devices, demonstrating that care should be taken to gather high-quality datasets for the critical pavement characteristic of macrotexture.

In this thesis, four experimental studies are reported. Two concern the surface structure of commercially relevant dental implant materials. Characterisation of four treated substrates supplied by Straumann AG was carried out. These include substrates equivalent to the commercially available SLA, SLActive and Roxolid implants. The materials vary in substrate alloy, commercially pure (grade 2) Ti and a TiZr alloy, and surface preparation treatments. All substrates are sandblasted and acid etched however post-etching one set are stored in air whilst the others are stored in saline. Within the work both substrate composition and surface treatment is shown to impact on the respective surface oxide thickness, crystallinity and morphology. The other two experimental studies concern calcium phosphate deposition from solution onto substrates. The first investigation is the deposition of calcium phosphate from a simulated body fluid onto implant-like substrates, shown to be structurally equivalent to the SLA and SLActive implant surfaces. The effect of surface modifications on calcium phosphate deposition is investigated; over the period investigated calcium phosphate did not deposit onto the SLA substrate, whilst deposition occurred within 3 days on the SLActive substrate. The role of Mg2+ ions in the simulated body fluid is also investigated, with increased [Mg2+] resulting in a longer induction period and modified crystallinity of the hydroxyapatite film formed. The final study is a model study of the initial calcium phosphate deposition on to substrates. TiO2 rutile (110) and Al2O3 corundum (0001) were prepared to be atomically flat and then exposed to a simple calcium phosphate solution. Changes in surface structure and surface chemistry over the first three hours of exposure were investigated. Deposition occurred rapidly on both substrates with a complete surface coverage after 3 hours.

Thesis (Ph.D. in Pharmaceutical Sciences) -- University of Colorado at Denver and Health Sciences Center, 2006. / Typescript. Includes bibliographical references (leaves 159-173). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;

Thesis (Ph. D.)--University of Washington, 1992. / Vita. Includes bibliographical references (leaves [205]-215).

No description available.

The radial heterogeneity of some columns used in high performance liquid chromatography (HPLC) was investigated using an on-column microelectrochemical amperometric detector. Such a detector allowed the recording of the elution profiles at different spatial positions throughout the column exit cross-section. From this, we obtain information about the radial distribution of the mobile phase velocity, column efficiency, and analyte concentration. In all cases, the results obtained show that the spatial distribution of the mobile phase velocity does not follow a piston-flow behavior but exhibits radial heterogeneity with differences not exceeding 5% between the center and wall regions of any column. The efficiency was found to be lower in the wall region of the column than in its core region (the central core with a radius of 1/3 the column inner radius) by up to 40-50% in some columns. The radial distribution of the maximum concentration of the peaks varies throughout the column exit section, partially due to the radial variations of the column efficiency. The technology used in constructing the microelectrochemical detectors was further exploited to fabricate and incorporate an online detector array for a pressurized flat wide column measuring 10x10x0.1 cm in dimensions. Thus, unlike traditional thin layer chromatography, samples in this pressurized flat bed are completely eluted and detected in a time-based mode just like they are in HPLC. Also, a lateral arrangement of the detector array allows for an easy monitoring of the homogeneity of the flat wide column. Also, information on the surface properties of three novel chemically bonded phase packing materials for HPLC was obtained using solid state cross-polarization (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopic experiments for the 29Si, and 13C nuclei. These packing materials were: Cogent bidentate C18 bonded to type-C silica, hybrid packing materials XTerra MS C18, and XBridge Prep. C18. The spectra obtained using cross-polarization magic angle spinning (CP-MAS) on the Cogent bidentate C18 bonded to type-C silica show the surface to be densely populated with hydride groups (Si-H), with a relative surface coverage exceeding 80%. The hybrid packing materials XTerra and XBridge gave spectra that reveal the silicon atoms to be bonded to alkyl moieties embedded in the molecular structure of these materials with over 90% of the alkyl silicon atoms found within the completely condensed silicon environments.