In order to understand the structural and electronic properties of titanium oxide nanoparticles of different sizes, the FIRE algorithm combining the simulated annealing method is employed to find the structures of TinO2n (n=1¡Ð6) nanoparticles with the global minimum potential energy. To deeply understand electronic properties, the relaxation structures of TinO2n (n=1¡Ð6) nanoparticle from previous method will be recalculated by density functional theory (DFT) method. The Fukui function, Frontier Molecular Orbital and density of state of TinO2n (n=1¡Ð6) nanoparticles are discussed for understanding the size effect of TiO2 nanoparticles on chemical reactivity. The adsorption and dissociation energy mechanism of the HN3 molecule and its fragments are also discussed and are compared with the mechanism about HN3 on the anatase surface.

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are persistent, ubiquitous, and toxic organic contaminants in coastal sediments. Being hydrophobic in water column, PAHs and PCBs tend to sorb rapidly on particles and eventually accumulate in sediments. Re-suspension of fine or low-density particles from the surface sediment would lead to release of the pollutants bound in sediment particles into water column. This study was to evaluate the potential of remobilization of sediment-bound pollutants into harbor water column by measuring the concentrations and compositions of PAHs and PCBs in different particle size (size fraction: 1000, 500, 250, 125 and 63 £gm) and the different density fractions (density: > 2.15, < 2.15 g/cm3) in the Kaohsiung Harbor area. The total PAH concentrations obtained from the sediments of Kaohsiung sub-channel (KH1) is higher than those of Shang-Zhu-Li fishing ferry (KH2), but it presents the opposite situation in total PCB concentrations. Total PAH concentrations are 3400 and 1700 (ng/g dw) and total PCB concentrations are 103 and 141 (ng/g dw) at sites of KH1 and KH2. PAH and PCB concentrations in the low-density fraction sediment made up more than 91% and 87% of the total concentration of the bulk sediment, respectively; while low-density fraction sediment made up only 4.3 to 7.7% of the bulk sediment in dry weight. According to the chemical fingerprinting, PAH source of Kaohsiung sub-channel (KH1) is from pyrogenic which might be from the diesel oil burning of shipping activities and containerized traffic. But the PAH sources in Shang-Zhu-Li fishing ferry (KH2) were from the combustion of coal and petroleum, which is possibly from iron and steel plant and the power plant nearby. The Toxic equivalents (TEQ) of dioxin-like PCBs in low and high-density fraction sediments were ranged from 1.1-7.6 pg-TEQ/g and 8.9-1500 pg-TEQ/g, respectively. Based on the Sediment Quality Guidelines (SQGs), only few PAH concentrations in the high-density fraction sediments were higher than the TEL value, while most of PAH concentrations in the low-density fraction sediments ranged between ERL and ERM values. This suggests the low-density sediment particles possessed higher potential of adverse effects to organisms in the aquatic environment.

In recent years, mining data streams has been widely studied. A data streams is a sequence of dynamic, continuous, unbounded and real time data items with a very high data rate that can only be read once. In data mining, clustering is one of use- ful techniques for discovering interesting data in the underlying data objects. The problem of clustering can be defined formally as follows: given n data points in the d- dimensional metric space, partition the data points into k clusters such that the data points within a cluster are more similar to each other than data points in different clusters. In the data streams environment, the difficulties of data streams clustering contain storage overhead, low clustering quality and a low updating efficiency. Cur- rent clustering algorithms can be broadly classified into four categories: partition, hierarchical, density-based and grid-based approaches. The advantage of the grid- based algorithm is that it can handle large databases. Based on the density-based approach, the insertion or deletion of data affects the current clustering only in the neighborhood of this data. Combining the advantages of the grid-based approach and density-based approach, the CDS-Tree algorithm was proposed. Although it can handle large databases, its clustering quality is restricted to the grid partition and the threshold of a dense cell. Therefore, in this thesis, we present a new clustering algo- rithm with high quality, GDense, for data streams. The GDense algorithm has high quality due to two kinds of partition: cells and quadcells, and two kinds of threshold: £_ and (1/4) . Moreover, in our GDense algorithm, in the data insertion part, the 7 cases takes 3 factors about the cell and the quadcell into consideration. In the deletion part, the 10 cases take 5 factors about the cell into consideration. From our simulation results, no matter what condition (including the number of data points, the number of cells, the size of the sliding window, and the threshold of dense cell) is, the clustering purity of our GDense algorithm is always higher than that of the CDS-Tree algorithm. Moreover, we make a comparison of the purity between the our GDense algorithm and the CDS-Tree algorithm with outliers. No matter whether the number of outliers is large or small, the clustering purity of our GDense algorithm is still higher than that of the CDS-Tree and we can improve about 20% the clustering purity as compared to the CDS-Tree algorithm.

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

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

Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 166-167). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (p. 242-256).

Thesis (M.U.D.)--University of Hong Kong, 2002. / Includes bibliographical references.

Thesis (Ph. D. (Physics and Electronics))--Rhodes University, 2003.

Lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) is a recently identified scavenger receptor expressed in endothelial cells and mediates the uptake of oxidized LDL (oxLDL). LOX-1 expression is increased in atherosclerotic lesions in animals and humans. Recent evidence has suggested that LOX-1 is involved in the development and progression of atherosclerosis. In addition to endothelial cells, it has also been reported that LOX-1 is also expressed by other cell types like macrophages. It is a multi-ligand class E scavenger receptor and cellular expression of LOX-1 can be induced by many of its ligands. The concentration of some of these ligands like oxLDL and advanced glycation end products (AGEs) are increased in the diabetic milieu. My hypothesis is that LOX-1 expression is increased in diabetes mellitus and LOX-1 activation may play a role in the development of micro- and/or macrovascular complications of diabetes. The objective of this thesis is to elucidate the role of LOX-1 in type 2 diabetes mellitus and its complications. The effect of modified LDL and AGEs on LOX-1 expression and the cellular response upon LOX-1 activation was investigated. In vitro studies have shown that both AGEs and oxLDL can activate and increase cellular expression of LOX-1 and the soluble form of LOX-1 (sLOX-1) in cultured endothelial cells. In addition, LDL modified by glycoxidation, is also a ligand of LOX-1 and glycoxidized LDL is even more potent than oxLDL in inducing LOX-1 expression. In patients with type 2 diabetes, serum level of sLOX-1 was significantly higher than non-diabetic normal control, indicating that LOX-1 expression was increased in diabetes. Serum levels of AGEs and glycoxidized LDL were important determinants of serum sLOX-1 level, and lowering serum AGEs led to a beneficial reduction in serum sLOX-1 concentration. Hence, AGEs was clearly an important ligand of LOX-1 in diabetes mellitus, and experiments were performed to further elucidate the underlying signaling pathway involved in the up-regulation of LOX-1 by AGEs. This was mediated by ligation of AGEs to the receptor for advanced glycation end products (RAGE) and activation of phosphoinositide 3-kinase. Mammalian target of rapamycin was a found to be a key downstream intermediary in AGEs-inducible LOX-1 expression in endothelial cells. I further demonstrated that LOX-1 was also expressed in human renal mesangial cells, and expression was at a low level at basal state but inducible by its ligands. Up-regulation of LOX-1 expression in activated mesangial cells resulted in increased oxidative stress, as well as increased production of proinflammatory cytokines, chemokines and growth factors. These experimental findings would suggest that LOX-1 might potentially be involved in renal inflammation and diabetic nephropathy. The above results collectively suggest that diabetes is associated with increased LOX-1 activation, and LOX-1 may play a role in the development of diabetic complications. Hence, LOX-1 might represent a suitable target for the future development of new strategies for treating and preventing diabetic vascular complications. / published_or_final_version / Medicine / Doctoral / Doctor of Philosophy