The template synthesis of rotaxanes and catenanes has allowed a detailed study of their intrinsically novel and interesting properties. A key strategy has been the deployment of transition metal ions with their well-defined coordination geometries allowing high-yielding and facile preparation of interlocked architectures. Knowledge of how to exploit the coordination sphere of metal ions and the design of ligands for the creation of intermediates that are pre-disposed to undergo ‘stoppering’ or ‘clipping’ has been a crucial requirement for this approach. This Thesis is in three parts describing the use of three dimensional, two dimensional and one dimensional coordination geometries in the synthesis of interlocked architectures. Firstly, the octahedral coordination geometry of cobalt(III) was utilized to organize dianionic pyridine-2,6-dicarboxamido ligands in a mutually orthogonal arrangement such that ring closing metathesis macrocyclizations gave access to interlocked or entwined products. A ‘figure-of-eight’ complex was obtained from a double macrocyclizations, whereas a catenate was accessed through a single macrocyclization. The topology of the isomers was proved by X-ray crystallography. An analogous [2]rotaxane was synthesized and the interlocked nature of the rotaxane demonstrated by 1H NMR spectroscopy and mass spectrometry. Secondly, an “active” metal template strategy, in which the metal ion plays a dual role – acting to both organize ligands and catalyze mechanical bond formation – allowed rotaxanes be constructed using the square planar coordination geometry and Lewis acidic nature of a palladium(II) complex. The interlocked nature of the rotaxane was proved by X-ray crystallography, demonstrating that a nitrile group present in the thread acted as a “station” for the Pd(II)-macrocycle. This observation led to the construction of a two “station” degenerate molecular shuttle in which the dynamics of translocation were controlled by reagent addition and observed by 1H NMR techniques. Lastly, the linear coordination geometry of gold(I) was successfully used as a template for construction of rotaxanes and catenanes via a ‘clipping’ strategy. The linear coordination geometry and the interlocked nature of the gold(I)-catenate was proved by X-ray crystallography, the rotaxane architecture was proved by 1H NMR spectroscopy and mass spectrometry. Chapters Two, Three and Four are in the form of articles that have been published in peer-reviewed journals, and are reproduced, in their published format, in the Appendix. No attempt has been made to rewrite the published work; as a consequence the numbering of compounds, whilst consistent within each Chapter, is not consistent throughout this Thesis. Another consequence is that the many failed synthetic routes have been left out. I hope the reader will forgive these omissions as well as the slight repetition that occurs in the introduction and bibliography of each chapter. Additionally, preceding each Chapter is a brief synopsis that places the work in context and acknowledges the contributions of my fellow researchers.

The work embodied in this thesis describes software techniques developed to analyse digital inline holograms of suspended particle fields, particularly in aquatic environ- ments. The primary motivation behind this work has been development of tech- niques to extract useable information from individual holograms within holovideos, producing focused silhouettes of recorded plankton and other particulates with min- imal user intervention. Two automated focusing algorithms are developed and presented in this work, both of which obtain comparable results for holograms of sparse plankton populations. The first approach is based on rectangular regions of interest (ROIs), which are aligned to (x, y) dimensions, and localise particles within the two-dimensional recon- structed planes obtained from holovideo frames. Due to poor immunity to particle merging when applied to denser particle fields, a second approach was developed using arbitrary polygons with which to localise particle positions in reconstructed planes. This new approach offers a greater immunity to the merging of particles lying in close proximity in the (x, y) dimensions of the hologram, and allows better particle localisation for high density particle holograms. Both ROI and polygon based particle localisation are explored to identify strengths and weaknesses, and complete automated scanning procedures developed in both cases. Examples are provided of typical output from automated scanning algorithms when applied to a number of sample holograms, and areas of weakness highlighted for future work.

Background: The study of circulating biomarkers and their association with disease outcomes has become progressively complex due to advances in the measurement of these biomarkers through multiplex technologies. The Least Absolute Shrinkage and Selection Operator (LASSO) is a data analysis method that may be utilized for biomarker selection in these high dimensional data. However, it is unclear which LASSO-type method is preferable when considering data scenarios that may be present in serum biomarker research, such as high correlation between biomarkers, weak associations with the outcome, and sparse number of true signals. The goal of this study was to compare the LASSO to five LASSO-type methods given these scenarios. Methods: A simulation study was performed to compare the LASSO, Adaptive LASSO, Elastic Net, Iterated LASSO, Bootstrap-Enhanced LASSO, and Weighted Fusion for the binary logistic regression model. The simulation study was designed to reflect the data structure of the population-based Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD), specifically the sample size (N = 1000 for total population, 500 for sub-analyses), correlation of biomarkers (0.20, 0.50, 0.80), prevalence of overweight (40%) and obese (12%) outcomes, and the association of outcomes with standardized serum biomarker concentrations (log-odds ratio = 0.05-1.75). Each LASSO-type method was then applied to the TESAOD data of 306 overweight, 66 obese, and 463 normal-weight subjects with a panel of 86 serum biomarkers. Results: Based on the simulation study, no method had an overall superior performance. The Weighted Fusion correctly identified more true signals, but incorrectly included more noise variables. The LASSO and Elastic Net correctly identified many true signals and excluded more noise variables. In the application study, biomarkers of overweight and obesity selected by all methods were Adiponectin, Apolipoprotein H, Calcitonin, CD14, Complement 3, C-reactive protein, Ferritin, Growth Hormone, Immunoglobulin M, Interleukin-18, Leptin, Monocyte Chemotactic Protein-1, Myoglobin, Sex Hormone Binding Globulin, Surfactant Protein D, and YKL-40. Conclusions: For the data scenarios examined, choice of optimal LASSO-type method was data structure dependent and should be guided by the research objective. The LASSO-type methods identified biomarkers that have known associations with obesity and obesity related conditions.

The purpose of this paper is to explore some of the properties of the Cantor set and to extend the idea of this set to metric spaces, in general, and to other sets of real numbers and sets in N-dimensional Euclidean space, in particular.

As esthetic improvement continues to be a primary goal of orthodontic patients and practitioners, it is important to understand the soft tissue movements that occur during the transition from rest to smile. Advances in technology allow capture of 3-dimesional photographs. The purpose of this study was to quantify the soft tissue changes that occur upon smiling and to compare changes between males and females using 3-dimensional photography. Fifty-four participants had resting and smiling photographs taken with the 3dMDface camera system. The two images were registered on stable facial surfaces, landmarks were placed, and measurements were recorded. Three-dimensional changes occurred in the following regions of the face in both males and females: eyes, ears, nose and lips. Intercommissure width of the lips was shown to increase more in females than males, but males showed increased mobility in landmarks at the base of the nose.

Multigenic diagnostic and prognostic tools can be derived for ordinal clinical outcomes using data from high-throughput genomic experiments. A challenge in this setting is that the number of predictors is much greater than the sample size, so traditional ordinal response modeling techniques must be exchanged for more specialized approaches. Existing methods perform well on some datasets, but there is room for improvement in terms of variable selection and predictive accuracy. Therefore, we extended an impressive binary response modeling technique, Feature Augmentation via Nonparametrics and Selection, to the ordinal response setting. Through simulation studies and analyses of high-throughput genomic datasets, we showed that our Ordinal FANS method is sensitive and specific when discriminating between important and unimportant features from the high-dimensional feature space and is highly competitive in terms of predictive accuracy. Discrete survival time is another example of an ordinal response. For many illnesses and chronic conditions, it is impossible to record the precise date and time of disease onset or relapse. Further, the HIPPA Privacy Rule prevents recording of protected health information which includes all elements of dates (except year), so in the absence of a “limited dataset,” date of diagnosis or date of death are not available for calculating overall survival. Thus, we developed a method that is suitable for modeling high-dimensional discrete survival time data and assessed its performance by conducting a simulation study and by predicting the discrete survival times of acute myeloid leukemia patients using a high-dimensional dataset.

The aim of investigating the 2D PbX6 inorganic organic hybrids was to study octahedral distortions, short interlayer spacing’s, and the effect of functionalized aliphatic’s terminal halogen on idealizing or destabilizing the octahedral arrangements and their effect on the band gap of the single layer 2D hybrid systems. It was found that the PbX6 metal centred distortions do display some impact on the band gap, the greater the distortion experienced in the Ieq-Pb-Ieq cis bond angles, the wider the band gap, as we suspect a decrease in I 5p antibonding character which lowers the top of the valence band. The terminal halogen interaction specifically in (BrC2)PbI4, clearly displayed some Br 4p/s character at the bottom of the conduction band, which may further explain the reduction of the band gap of this compound. This in conjunction with the shorter interlayer spacing serve to stabilize more idealized bridging angles, as seen in both the lead iodide and bromide analogues. In the short interlayer spacing compounds large idealizations of the Pb-X-Pb bridging angles are observed however display a large metal centred octahedral distortions in order accommodate the spatial occupation of the lone pair on lead. It was generally observed that the lead bromide hybrids appear to have a greater sensitivity to exciton lattice interactions, which give rise to red shifted emissions and absorptions with decreasing temperature. Structurally this behaviour is counterintuitive; because the structures increase in inorganic distortions with decreasing temperature and therefore a blue shift in the exciton absorption is expected. It should be noted that compounds displaying this phenomenon most, (C4, C6, C7)PbBr4 do display a large amount of structural disorder in their lower temperature phases. In the 1D systems investigated further structure to property correlations were made. Optically it was found that unlike the corner-shared perovskite type 1D wires of [NH2C(I)=NH2]3PbI5 and [CH3SC(=NH2)NH2]3PbI5 the first exciton absorption of the octahedral face sharing wires of (A)PbI3 appear to be largely insensitive to the inorganic structural distortions experienced as a result of the low temperature phase transitions. In one instance however a low temperature phase transition did result in a polaron emission which was directly related to a discontinuity in the inorganic wires. More generally experimental links between the STE luminescence emissions and the inter-wire spacing, organic dielectric constant, and the density of the crystal, were shown to influence the STE lattice interactions to a greater degree. This effect is increased through a decrease in crystal density and organic dielectric constant, with an associated increase in the inter-wire spacing. Therefore as the exciton lattice interactions increase, a red shift in the STE emissions is observed. In another series of systems strong 1- and interactions were present in particularly two 1D charge transfer compounds. It was noted that the inorganic wires promote interactions between the organic templates as has also been established in literature. Structurally it was also observed that the CT transitions of these compounds begin to largely coincide with the STE emission arising from the inorganic wire. Even though the CT compounds structurally have strong interactions the current experiments do not ascertain to what degree this interaction assists in electron transport. It was also established that as intermolecular interactions are absent in previously published MV and Et compounds with the dominant CT interaction was the I…N interaction which functions over a large range (4.9A). This long distance is substantiated from the strong covalent character of the I…N interaction observed in IR experiments completed on (MV)Pb2I6. It was also observed in our compounds that the position of the LUMO of the organic cation relative to the valence band of the inorganic wires appears to be largely dependent on the N…I distance and largely independent of the electron accepting templates HOMO-LUMO gap. The increased wire thickness observed in these compounds does appear to display a pronounced effect on the PL emissions as seen in three chain wide wires produced. The thicker chains begin to allow higher energy emission’s to occur i.e. the desired first exciton emission begins to become favored due to the relaxing of the wires spatial confinement on the electron-hole’s orbit. Further investigations are needed into even thicker chain wires, in order to ascertain the ideal size of the wire to obtain the desired high energy first exciton emission. To date the wire thickness that does give rise to the first exciton emission appears to still need at least six coordinated PbI6 octahedral units.

A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in ful lment of the requirements for the degree of Master of Science. Johannesburg 2016. / Low dimensional carbon systems are of immense interest in condensed matter physics due to their exceptional and often startling electric and magnetic properties. In this dissertation we consider two of these materials - graphene and nanocrystalline diamond. The effect of synthesis parameters on the quality of graphene is examined and it is found that controlling the partial pressure of the synthesis gases plays a critical role in determining the quality of the sample. Superconductivity in Boron doped nanocrystalline diamond (B-NCD) is considered and weak localisation along with a Berezinsky-Kosterlitz-Thouless (BKT) transition is identified in the samples. Furthermore we explore theoretically the problem of electric transport through a double quantum dot system coupled to a nanomechanical resonator. We find resonant tunnelling when the difference between the energy levels of the dots equals an integer multiple of the resonator frequency, and that while initially increasing the electron phonon coupling (g) increases the current through the sample further increase in g inhibits electric transport through the quantum dots. / LG2017

在本論文中，我們利用簡單的濕化學氧化鋅(ZnO)納米線陣列模板法成功地製備了一系列具有不同化學成份、晶體結構和形貌的準一維鋅-鐵-氧納米結構陣列。 / 垂直排列的ZnO納米線陣列首先生長在不同的襯底上，然后进一步被用作其他納米結構陣列的生長模板。ZnO納米線不僅僅起到骨架定型的作用，最終還可以为后續納米結構提供原料组分。通過控制ZnO和氯化鐵溶液的反應時間，在煅燒后，我們可以製備ZnO/鐵酸鋅(ZnFe₂O₄)納米線纜陣列，以及化學/非化學計量的ZnFe₂O₄、ZnFe₂O₄/α-三氧化二鐵(α-Fe₂O₃)和α-Fe₂O₃納米管陣列。ZnFe₂O₄和α-Fe₂O₃納米管陣列都表現出了對可見光的吸收，它們的帶隙經估算分別是2.3 eV和1.7 eV。 / 通過電子能量損失譜(EELS)，可以得到ZnFe₂O₄納米管陣列的一些細節的結構信息。我們分別研究了兩個不同系列(溫度和化學計量)的ZnFe₂O₄納米管。研究發現，樣品的磁性和它們的晶體結構有著非常緊密的關係。首先，對於溫度系列的樣品，當樣品的燒結溫度從600 °C降到400 °C時，更多的三價鐵離子(Fe³⁺)佔據了尖晶石結構中的A位置(四面體位置)而並非它們本應佔據的平衡B位置(八面體位置)。這種偏離了正常尖晶石結構的情況使得A和B位置上的Fe³⁺的超交換作用增加，進而增加了樣品的阻隔溫度(TB)，磁各向異性常數(K)，3K和300 K下的飽和磁化強度(MS)和3K下的矯頑力(HC)。同時使3K和300K下的MS的比值變小。其次，對於化學計量系列的樣品，通過比較在同一燒結溫度下製備的化學計量和非化學計量的ZnFe₂O₄納米管，我們發現在鐵鋅比大於2的納米管中，Fe³⁺佔據A和B位置的比例和化學計量的樣品是类似的。這些多出的Fe³⁺也會增加超交換作用，從而導致較大的TB, K, MS(3K和300 K)，HC(3K)和較小的MS(3 K)/MS(300 K)比值。最後，作為非化學計量的極端情況，α-Fe₂O₃納米管在小的外加磁場下表現出了典型的Morin相變，在大的外加磁場下出現了場致spin-flop轉變。 / 另一方面，我們發現，當使用羅丹明B(RhB)作為指示劑時，ZnO/ZnFe₂O₄納米線纜陣列表現出了優於纯ZnO和纯ZnFe₂O₄納米管陣列的可見光降解活性，但是它們的降解路徑各不相同。ZnO由於染料敏化機制而具有可見光降解能力，但是其降解活性最差。ZnO/ZnFe₂O₄納米線纜陣列和ZnFe₂O₄納米管陣列的基本降解原理是相同的，那就是，利用有可見光活性的ZnFe₂O₄中的光生電子和空穴所生成的活性自由基降解RhB。但是，ZnO/ZnFe₂O₄納米線纜陣列的降解能力明顯優於ZnFe₂O₄納米管陣列，這是由於ZnO與ZnFe₂O₄之間的II型能帶匹配顯著地促進了光生電子和空穴的分離。 / In the present thesis, several kinds of pseudo-one-dimensional Zn-Fe-O nanostructure arrays with tunable chemical compositions, crystal structures and morphologies are successfully synthesized via a simple wet-chemical ZnO-nanowire-array templating method. / Vertically-aligned ZnO nanowire arrays are firstly fabricated on several different substrates and then serve as templates for other nanostructured arrays growth. The ZnO nanowires not only act as morphology-defining skeleton but also contribute chemically to the final composition of the nanostructures. By controlling the reaction time between ZnO and FeCl₃ solution, ZnO/ZnFe₂O₄ nanocable arrays, stoichiometric ZnFe₂O₄ nanotube arrays, nonstoichiometric ZnFe₂O₄ nanotube arrays, ZnFe₂O₄/α-Fe₂O₃ nanotube arrays and α-Fe₂O₃ nanotube arrays can be synthesized in a controlled manner after calcination. Both ZnFe₂O₄ and α-Fe₂O₃ nanotube arrays exhibit visible light absorption and their bandgap are estimated to be ~2.3 eV and ~1.7 eV, respectively. / The detailed structural information of the ZnFe₂O₄ nanotube arrays are obtained by electron energy loss spectroscopy (EELS). In particular, EELS are carried out for two different series (i.e., temperature and stoichiometric series). The magnetic properties of these samples are found to closely correlate to their structural characteristics. Firstly, with the decrease of the calcination temperature from 600 °C to 400 °C, more Fe³⁺ions occupy A sites (tetrahedral sites in spinel structure) rather than their equilibrium B sites (octahedral sites in spinel structure). The deviation from the normal spinel structure leads to the enhancement of superexchange interactions between Fe³⁺ions in A and B sites, and thus results in an increase in blocking temperature (TB), magnetic anisotropic constant (K), saturation magnetization (MS, at 3 K and 300 K), coercivity (HC, at 3 K) and a decrease in MS(3 K)/MS(300 K) ratios. Secondly, by comparing stoichiometric and nonstoichiometric ZnFe₂O₄ nanotubes calcinated at the same temperature, we found that the nonstoichiometric nanotubes (Fe:Zn > 2) shows similar ratios of Fe³⁺in A and B sites to that of the stoichiometric one. The extra Fe³⁺in the crystal also enhances the superexchange interactions of Fe³⁺, which results in larger TB, K, MS(at 3 K and 300 K) and HC(at 3 K), and smaller MS(3 K)/MS(300 K) ratio. Lastly, α-Fe₂O₃ nanotubes, as an extreme case of the nonstoichiometric sample, show typical Morin-transition characterization under small external field, and field-induced spin-flop transition at large external field. / On the other hand, we found that the visible-light-driven photodegradation activities of ZnO/ZnFe₂O₄ nanocable arrays are superior to those of the ZnO nanowire arrays and ZnFe₂O₄ nanotube arrays using RhB as the probe molecules. All the three nanostructures show degradation of RhB molecules under visible light irradiation, but they take different degradation pathways. The degradation of RhB in the presence of ZnO nanowire arrays is attributed to the dye-sensitized mechanism, and the photodegradation activity is the worst. ZnO/ZnFe₂O₄ nanocable arrays and ZnFe₂O₄ nanotube arrays have the same degradation mechanism, that is, reactive radicals produced by photogenerated electron-hole pairs in the visible-light-active ZnFe₂O₄ are responsible for the photodegradation of RhB. However, the nanocable arrays show much higher degradation capability. This is owing to the type II band alignment between ZnO and ZnFe₂O₄, which greatly promotes the separation of photogenerated electronsand holes in ZnFe₂O₄. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Guo, Xuan = 準一維鋅-鐵-氧納米結構陣列 : 控制製備, 磁學性質以及光催化方面的應用 / 郭璇. / Thesis (Ph.D.) Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 107-117). / Abstracts also in Chinese. / Guo, Xuan = Zhun yi wei xin-tie-yang na mi jie gou zhen lie : kong zhi zhi bei, ci xue xing zhi yi ji guang cui hua fang mian de ying yong / Guo Xuan.

by Chu Kin-cheong. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1988. / Bibliography: leaves 106-109.