published_or_final_version / Physics / Doctoral / Doctor of Philosophy

In mammals, development of a new organism requires fertilisation of the female egg by sperm. The resulting zygote develops into the blastocyst stage as it travels towards the uterus. Within the uterus, the blastocyst invades the maternal tissues and establishes access to the maternal blood supply. This process is called implantation and is absolutely essential for the further development of the conceptus and establishment of pregnancy. Successful implantation requires a proper preparation of the uterus and the embryo as well as a molecular dialogue between the embryo and the uterine tissues. Female mice that have a disruption in the Plcβ1 gene are infertile. In the course of this Thesis it became apparent that the main cause of their infertility is their inability to implant their embryos. PLCβ1 protein is a mediator of G-protein coupled receptor (GPCR) signalling and it is involved in the production of second messengers essential for downstream transmission of signals. A host of reproductive functions are under the control of GPCR signalling. In this PhD Thesis the infertile phenotype of Plcβ1 knockout (KO) female mice was investigated to identify the reproductive processes affected by the lack of a functional PLCβ1 protein. A combination of histological, molecular biology and in vivo techniques were utilised to show that at the time of implantation, embryos fail to attach to the uterine epithelium of KO uteri. In addition, it was demonstrated that estrogen signalling and components of the endocannabinoid metabolism, both key processes for successful implantation are severely altered in KO uteri. These observations show that KO uteri fail to prepare for implantation. In addition, the KO reproductive tract exerts a detrimental effect on pre- and peri- implantation embryo development. Currently, failure of implantation is thought to be one of the major causes of infertility in women and up to this date there are no successful treatments. The results of this project expand our current knowledge on the physiology of implantation and provide cues for the development of diagnostic markers and treatments for the women who are unable to conceive.

Im Rahmen dieser retrospektiven Studie wurden 29 Patienten (Durchschnittsalter 49,8 Jahre, Follow-up im Mittel nach 15,7 Monaten), die mit dem Oberflächenersatz nach Copeland versogt wurden, klinisch und mit bildgebenden Maßnahmen untersucht. Die Zielvariablen waren der Constant-Score und eine metrische Analyse der postoperativen Implantatlage (humorales Offset und Overstuffing). Es zeigte sich bei allen Patienten eine signifikante Verbesserung der Schulterfunktion. Der präoperative Constant-Score von 22,4 Punkten (27,2% im altersadaptierten Score) wurde auf 47,6 Punkte (57,6% im altersadaptierten Score) postoperativ signifikant gesteigert. Deutliche und statistisch signifikante Verbesserungen konnten in allen Bereichen des Constant Scores erreicht werden, wobei die Kategorie Schmerz am stärksten und die Kategorie Kraft am geringsten profitiert. Es zeigte sich bei der metrischen Analyse eine gute Rekonstruktion der Anatomie. Eine signifikante Korrelation des postoperativen Offsets und Radius mit dem postoperativen Constant-Score wurde nicht beobachtet. Die besten Ergebnisse waren bei den avaskulären Humeruskopfnekrosen und den Instabilitätsarthropathien zu finden. Im Vergleich zu anatomischen Totalendoprothesen und inversen Modellen bringt der Oberflächenersatz des Humeruskopfes schlechtere funktionelle Ergebnisse bei ähnlich guter Schmerzreduktion. Der Vorteil liegt in einer wesentlich besseren Erhaltung der Knochensubstanz und im Falle von Komplikationen in günstigeren Revisionsmöglichkeiten. / In this study (in retrospect) 29 patients (mean age 49.8 years, mean follow-up 15.7 months), have been investigated clinically and image-guided after implantation of Copeland surface replacement. Target variable have been Constant-Score and a metrical analysis of the postoperative position of the prosthesis (humeral offset and overstuffing). All patients showed a significant improvement of shoulder function. Preoperative absolute Constant-Score of 22.4 points (27.2% adapted score) improved to 47.6 points (57.6%). Considerable and significant amendment could be reached in all categories of the Constant-Score. The best profit showed the category of pain in contrast to the category of strength. A sound reconstruction of anatomy was found due to metric analysis. There was no correlation found out between postoperative offset, radius and postoperative Constant-Score. Best outcome was found in the group of avascular necrosis of the humeral head and instability arthropathy. In comparison to total shoulder replacement and reverse shoulder arthroplasty outcome after surface replacement is less in shoulder function but similar in reduction of pain. Surface replacement has the advantage of sustainmant of bone substance and in case of complications in a better possibility for revision.

Ph.D., Faculty of Engineering and the Built Environment, University of the Witwatersand, 2012 / This thesis focuses on the boron suboxide B6O, a boron-rich super-hard ceramic material. With hardness values previously reported between 24 GPa and 45 GPa, B6O is one of the hardest known materials. Although first reports on boron suboxides date back as far as 1909 (Weintraub E., Transactions of the American Electrochemical Society, 16 (1909) 165), it is the B6O-based composites that have attracted considerable interest in recent years due to their enormous technological potential, especially as an alternative to polycrystalline diamond and polycrystalline cubic boron nitride for wear and abrasive applications. Investigations into the properties of B6O itself appear to have been neglected in favour of the improvement of densification and fracture toughness of the composites. The B6O samples used for the work reported in this work was hot-pressed was prepared under an argon environment at 1800 C and 50 MPa for 20 minutes followed metallographical preparation. The density of the hot-pressed compacts measured 2.44 g/cm3. The starting B6O powder material was supplied from the Fraunhofer Institute for Ceramic Technologies and Systems, Dresden. This thesis primarily seeks to generate and report as much practical data for polycrystalline B6O materials prepared by uniaxial hot-pressing as possible from a variety of characterization techniques. Firstly, the Raman spectra of hot-pressed B6O, which was until now poorly understood, was investigated using using a 514.5 nm green Ar+ laser excitation source. Secondly, the fundamental nature of some mechanical properties of hot-pressed B6O were investigated by means of Vickers and Berkovich indentation techniques. New approaches for data analysis, especially the investigations of the nanomechanical properties of hot-pressed B6O by Berkovich nanoindentation, were also suggested. Thirdly, the intrinsic hardness of hot-pressed B6O was investigated by means of a comprehensive inter-model comparison study. Fourthly, a combined experimental and simulation approach for determining mechanical properties of hot-pressed B6O by nanoindentation was also carried out, based on the outcomes of the study, the deformation response of the material under dynamic indentation was investigated at di erent stages using a custom developed finite element model. Finally, based on the preliminary ab initio density functional calculations of the structural properties of B6O conducted by Lowther showing that the presence of a high electronegativity interstitial in the B6O structure could enhance the strength of the bonding in B6O, fluorine ion implantation into B6O were conducted. The e ects to the structural and the nanomechanical properties of radiation damage induced by ion implantation was investigated. The possible formation of novel nanostructures in the ion-irradiated B6O matrix near-surface was also investigated. Results obtained from this study provides a vast amount of practical data for hot-pressed B6O materials as well as a number of novel analysis approaches for the extraction useful properties from the measured raw data. Firstly, using an automated background subtraction method, observable first- and second-order Raman spectra of B6O were obtained. A comparative analysis with previously reported spectra of other -rhombohedral boron-rich ceramic materials demonstrate a good agreement. Results also confirm the existence of highly resolved Raman modes measured at ambient conditions using a green Ar+ excitation source which is contrary to the conventional understanding. Secondly, results from the micro-indentation investigations indicate the measured microhardness exhibits indentation load dependence. A model inter-comparison study of indentation size e ects in the microhardness measurements of hot-pressed B6O is comprehensively discussed. Thirdly, the intrinsic hardness value of 30 GPa was deduced. Fourthly, a quantitative analysis approach was developed to simulate multi-cycling loading load-displacement curves from a single measured load-displacement nanoindentation curve. Based on the results, the nature of the indentation size e ect in the nanoindentation hardness as well as the intrinsic nanomechanical properties of hot-pressed B6O were established. Fifthly, a combined experimental and finite element method simulation approach for determining mechanical properties of hot-pressed B6O by nanoindentation was developed. Based on the outcomes of the combined experimental and simulation studies, the deformation response of the material under dynamic indentation was also investigated at di erent stages using a custom developed finite element model. Finally, results from the structural characterization of the ion implanted B6O material demonstrates the formation of novel nanostructures by means of the ion bombardment of B6O. In addition, the study presented here also seeks to investigate the e ects of the fluorine ion implantation on the near-surface nanomechanical properties of hot-pressed B6O. The principal conclusions that the study provide are both comprehensive practical data for B6O materials prepared by uniaxial hot-pressing. A number of properties, including the Raman spectra, the intrinsic hardness, and the radiation resistance and the e ects of radiation damage are reported in the thesis.

PhD, Faculty of Science, University of the Witwatersrand

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Doctor of Philosophy. / High purity natural type Il a diamond specimens were used in this study. Conducting layers in the surfaces of these diamonds were generated using low-ion dose multiple implantation-annealing steps. The implantation energies and the ion-doses were spread evenly to intermix the point-defects, thereby increasing the probability of interstitialvacancy recombinations and promoting dopant-interstitial-vacancy combination resulting in activated dopant sites in the implanted layers. The process used to prepare our samples is known as cold-implantation-rapid-annealing (CIRA). Carbon-ion and boron-ion implantation was used to prepare the diamond specimens, and de-conductivity measurements in the temperature range of 1.5-300 K were made following each CIRA sequence. An electrical conductivity crossover from the Mott variable range hopping (VRH) to the Efros-Shklovskii VRH conduction was observed when the temperature of insulating samples was lowered. The conductivity crossover temperature Tcross decreases with increasing concentration of the boron-ion dose in the implanted layers, indicating the narrowing of the Coulomb gap in the single-particle density of states near the Fermi energy. (Abbreviation abstract) / Andrew Chakane 2019

Ovarian hyperstimulation is achieved through ovarian gonadotropin stimulation, and thus associated with supraphysiological levels of oestrogen and progesterone. To investigate the effects of exogenous gonadotropins on the expression of TGF b1 and TGF b2, which have been recognized as possible modulators of many endometrial functions, FSH and hCG were superimposed upon the normal hormonal milieu of the cycling rat, prior to mating. Endometrial tissue was collected at 4.5, 5.5 and 6.5 days after mating. ELISA was performed to estimate blood oestrogen and progesterone levels and immunohistochemistry was undertaken to localize TGF b1 and TGF b2 in the uterine endometrium. Apart from the known detrimental effects of hyperstimulation on gross morphology, hormone levels and endometrial histology, the hyperstimulation was also found to affect TGF b expression. An increase in the expression of TGF b2 was distinct in the glandular epithelium of the hyperstimulated animals, while regionalized expression of both TGF b1 and TGF b2 was prominent in the stroma. In conclusion, hyperstimulation affects the expression of both TGF b1 and TGF b2, which may contribute to the disruption of the endometrial environment required for successful embryo implantation.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, June, 2013 / Diamond with its outstanding and unique physical properties offers the opportunity to be used as semiconductor material in future device technologies. Promising ap- plications are, among others, high speed and high-power electronic devices working under extreme conditions, such as high temperature and harsh chemical environments. With respect to electronic applications, a controlled doping of the material is neces- sary which is preferably done by ion implantation. The ion implantation technique allows incorporation of foreign atoms at de¯ned depths and with controlled spatial distribution which is not achievable with other methods. However, the ion implanta- tion process is always connected with the formation of defects which compensate and trap charge carriers thus degrading the electrical behaviour. It is therefore essential to understand the nature of defects produced under various implantation conditions. In this respect, this study involves the investigation of the nature of the radiation damage produced during the multi-implantation of carbon ions in synthetic high- pressure, high-temperature (HPHT) type Ib diamond spread over a range of energies from 50 to 150 keV and °uences, using the cold-implantation-rapid-annealing (CIRA) routine. Single energy implantation of carbon ions in synthetic HPHT (type Ib), at room temperature, was also performed. Both ion milling and FIB (Focused Ion Beam) milling were used to prepare thin specimen for transmission electron micro- scope (TEM) analysis. The unimplanted, implanted and annealed samples were characterized using trans- mission electron microscopy based techniques and Raman spectroscopy. ii iii In unimplanted type Ia natural diamond, a high density of platelets, exhibiting the typical contrast of both edge-on and inclined platelets on f100g planes was found. As-implanted HPHT type Ib diamond, implanted with single energy of 150 keV car- bon ions and °uence of 7£1015 ions cm¡2 revealed an amorphous diamond layer of about 80 nm in thickness while, for low °uence implantations, the damaged diamond retained its crystallinity after annealing at 1600 K. In addition, damaged diamond transformed into disordered carbon comprising regions with bent (002) graphitic fringes and regions of amorphous carbon when high °uence, i.e., one above the amor- phization/graphitisation threshold were used followed by rapid thermal annealing at 1600 K. Furthermore, the interface between the implanted and annealed layer and the diamond substrate at the end of the range, showed diamond crystallites, inter- spersed between regions of amorphous carbon and partially graphitized carbon. This indicates that solid phase epitaxial recrystallization regrowth in diamond does not occur.

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by Chung Pui Shan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 105-110). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iii / Table of contents --- p.v / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Metal clusters embedded in fused silica glass --- p.2 / Chapter 1.2 --- Ion implantation of metal clusters --- p.3 / Chapter 1.3 --- Feature of MEVVA implantation --- p.5 / Chapter 1.4 --- Motivation and organization of this thesis --- p.7 / Chapter Chapter 2. --- Sample Preparation and Characterization Methods / Chapter 2.1 --- MEVVA implantation --- p.9 / Chapter 2.2 --- TRIM simulation --- p.11 / Chapter 2.3 --- Sample preparation --- p.14 / Chapter 2.4 --- Rutherford backscattering spectroscopy (RBS) --- p.16 / Chapter 2.5 --- X-ray diffraction (XRD) technique --- p.17 / Chapter 2.6 --- X-ray photoelectron spectroscopy (XPS) --- p.21 / Chapter 2.7 --- Transmission electron microscopy (TEM) technique --- p.24 / Chapter 2.8 --- Spectroscopic ellipsometry (S.E.) --- p.25 / Chapter 2.9 --- Z-scan technique --- p.32 / Chapter Chapter 3. --- Characterization of Single Implanted Samples / Chapter 3.1 --- Experimental results and discussion / Chapter 3.1.1 --- RBS --- p.35 / Chapter 3.1.2 --- XRD --- p.38 / Chapter 3.1.3 --- XPS --- p.42 / Chapter 3.1.4 --- XTEM --- p.49 / Chapter 3.1.5 --- S.E --- p.54 / Chapter 3.1.6 --- Z-scan measurements --- p.60 / Chapter 3.2 --- Summary --- p.65 / Chapter Chapter 4. --- Characterization of Sequentially Cu-Ni Implanted Samples / Chapter 4.1 --- Experimental results and discussion / Chapter 4.1.1 --- XRD --- p.66 / Chapter 4.1.2 --- XPS --- p.68 / Chapter 4.1.3 --- XTEM --- p.77 / Chapter 4.1.4 --- Z-scan measurements --- p.87 / Chapter 4.2 --- Summary --- p.91 / Chapter Chapter 5. --- Conclusion and Future Works / Chapter 5.1 --- Conclusion --- p.92 / Chapter 5.2 --- Future works --- p.93 / Appendix / Appendix I --- p.94 / Chapter ☆ --- Sample preparation procedures for XTEM / Appendix II --- p.97 / Chapter ☆ --- Alignment procedures of S.E. / Chapter ☆ --- Implementation of the Merlin system / Appendix III --- p.101 / Chapter ☆ --- Calibration of S.E. / Reference --- p.105