In the global context of increasing oil prices and public concern regarding the safety of nuclear plants, renewable forms of energy are called upon to play a major role in tomorrow’s energy market. Among the various forms of renewable energies, solar power holds the greatest potential for development. Despite the constant improvement of photovoltaic technologies over the past few year, these technologies are rapidly approaching the theoretic performance limits. New ideas and materials are required to overcome this bottleneck and to take full advantage of solar power. With a band-gap energy spanning the full solar spectrum, and an absorption coefficient ten times higher than competing materials, indium gallium nitride alloys are amongst the most promising solar-cell materials. Nevertheless, fundamental issues related to the fabrication and doping of InGaN alloys still hamper the development of InGaN-based photovoltaics. In the present thesis, conducted within the framework of the ANR project NewPVonGlass, the growth of InGaN alloys suitable for photovoltaics using metalorganic vapor-phase epi- taxy (MOVPE) is studied. A combination of several cutting-edge characterization tools is employed to determine the fundamental mechanism that govern the growth of InGaN. Based on the results of this study, an innovative procedure that allows the growth of hig-quality InGaN epitaxial layers is demonstrated and is used for the fabrication of InGaN-based solar cells.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: HISTORICAL PERSPECTIVE Stem cell therapy was commenced after using rabbits as research models. Once this process was successful, the first human transplant was done in 1974. Certain prerequisites were necessary and these were achieved - a protected environment, an apheresis unit, protocols and accreditation with International Registries. Initially, unmanipulated bone marrow and peripheral blood stem cells were used together with immunosuppressive drugs followed by the use of Cyclosporin A then the addition of ex vivo Campath®. AUDIT OF ACUTE ASSOCIATIONS (468 subjects in initial cohort) NEPHROLOGY Creatinine was used as an indication of renal function. Of the 76 available for analysis, 47% had acute kidney injury. Dialysis had a poor outcome as reported in the literature. Renal complications occurred frequently mostly due to infection. CARDIOLOGY A total of 119 individuals were available for analysis. Echocardiograms and electrocardiograms were part of pre-transplant assessment. Left ventricular systolic dysfunction predicted for increasing post transplant problems. Cardiac complications occurred at a lower frequency than other post-transplants side-effects consistent with the published data. DERMATOLOGY Cases were evaluated on a daily basis and referred to a dermatologist when necessary. To confirm Graft-Versus-Host Disease (GVHD), a skin biopsy was done to differentiate it from drug hypersensitivity or viral infections. The exposure to ex vivo Campath® significantly improved outcome by reducing the incidence and severity of GVHD. Quality of life was enhanced with substantial cost saving. GASTROENTEROLOGY Foregut symptoms occurred in 90% of patients. Nutritional problems were encountered. Altered liver functions were relatively common attributable to drugs, sepsis and conditioning regimens. Liver biopsies were not performed in this series and endoscopy performed only when necessary. A STUDY ON LATE COMPLICATIONS (55 subjects) RESPIRATORY Spirometry and diffusing capacity were done in this cohort. All the lung function studies were within the predicted normal range apart from some marginal reduction in diffusing capacity. In none of these patients did late consequences such as Bronchiolitis Obliterans Organising Pneumonia and Late Onset Non-Infectious Pulmonary complications occur. Cytomegalovirus reactivation was common but early intervention prevented serious complications. IMMUNOLOGY An in vitro functional study was done. Both the innate and adaptive systems were evaluated. Taken into consideration were the type of transplant, age from transplant, diagnosis and conditioning. The granulocyte Burst-test was done for the innate profile. Reduced activity was shown in all the subgroups. It appears as if the innate response of the granulocytic cells never recovered due to reduced granulocytic function in vitro. The adaptive responses were evaluated in vitro and only the autografts showed better CD4+ and CD8+ cytokine production. No major differences were seen in other groups. Normal cytokine production by CD4+ and CD8+ T cells were present when these were activated in vitro to produce regulatory cytokines, implying that their lymphoid component was intact post-transplant. BONE DISEASE Here both the Dual energy X-ray Absorptiometry (DXA) and Quantitative Computed Tomography (QCT) were used to evaluate bone mineral density. There was a discrepancy present between the two modalities. DXA showed no osteoporosis but QCT 22%. Biomarkers were normal in all. There was no history of fracture and no objective evidence of vertebral fractures using vertebral fracture assessment. Although QCT was used for the study, DXA remains the gold standard in South Africa. CONCLUSION This doctoral provided information on the non-haematological consequences in South Africa with the use of Campath® ex vivo. / AFRIKAANSE OPSOMMING: HISTORIESE PERSPEKTIEF Stamsel terapie is voortgesit nadat konyne aanvanklik as navorsingsmodelle gebruik is. Na suksesvolle voltooiing van hierdie proses, is die eerste menslike oorplanting gedoen in 1974. Sekere voorvereistes was nodig en hierdie was bereik – ʼn beskermde omgewing, ʼn aferese eenheid, protokolle en akkreditasie by Internasionale Registers. Aanvanklik is ongemanipuleerde beenmurg- en perifere bloed stamselle gebruik, tesame met immuunonderdrukkende middels, gevolg deur die gebruik van Sikloporien A en daarna die toevoeging van ex vivo Campath®. OUDIT VAN AKUTE ASSOSIASIES (468 GEVALLE IN DIE OORSPRONKLIKE GROEP) NEFROLOGIE Kreatinien is gebruik as ʼn aanduiding van nierfunksie. Van die 76 gevalle beskikbaar vir ontleding, het 47% akute nierbeserings gehad. Dialise het ʼn swak uitkoms gehad soos gerapporteer in publikasies. Nier komplikasies het gereeld voorgekom, meestal as gevolg van infeksie. KARDIOLOGIE ʼn Totaal van 119 gevalle was beskikbaar vir ontleding. Eggokardiogramme en elektrokardiogramme was deel van die pre-oorplanting assessering. Linker ventrikulêre disfunksie was voorspelbaar van verhoogde postoorplanting probleme. Kardiale komplikasies het konstant volgens publikasies minder geredelik voorgekom as ander post-oorplantings newe-effekte. DERMATOLOGIE Gevalle is op ʼn daaglikse basis geëvalueer en verwys na ʼn dermatoloog wanneer nodig. ʼn Velbiopsie is gedoen om “Graft-Versus-Host” siekte (GVHD) te bevestig en dit te onderskei van middel hipersensitiwiteit of virale infeksies. Die blootstelling aan ex vivo Campath® het uitkomste aansienlik verbeter deur die voorkoms en erns van GVHD te verminder. Kwaliteit van lewe is verhoog met aansienlike koste besparing. GASTROENTEROLOGIE Boonste gastro-intestinale simptome het voorgekom in 90% van die pasiënte. Wanvoeding het voorgekom.. Abnormale lewerfunksies was relatief algemeen toeskryfbaar aan middels, sepsis en kondisionerings protokolle. Lewer biopsies is nie in hierdie reeks uitgevoer nie en endoskopie slegs wanneer dit noodsaaklik was. DIE STUDIE VAN LAAT KOMPLIKASIES (55 GEVALLE) RESPIRATORIES Spirometrie en diffusie kapasiteit is gedoen in hierdie groep. Al die longfunksie ondersoeke was binne die voorspelde normale waardes behalwe ʼn paar marginale afnames in die diffusie kapasitiet. In geen van hierdie pasiënte het laat nagevolge soos Bronchoilitis Obliterans Organiserende Pneumonie en Laat Aanvangs Nieinfektiewe Long komplikasies voorgekom nie. Sitomegaal virus heraktivering was algemeen maar vroeë intervensie het ernstige komplikasies voorkom. IMMUNOLOGIE ʼn In vitro funksionele studie is gedoen. Beide die spesifieke en nie-spesifieke immuun stelsels is geëvalueer. Die tipe oorplanting, tyd vanaf oorplanting, diagnose en kondisionering is in ag geneem. Die “Granulocyte Burst” toets is gedoen vir die nie-spesifieke profiel. Verminderde aktiwiteite is bewys in al die subgroepe. Dit wil voorkom asof die nie-spesifieke respons van die granulosiete nooit herstel nie as gevolg van die verlaagde in vitro granulosiet funksie. Die spesifieke immuun respons is in vitro geëvalueer en slegs die outotransplantaat het beter CD4+ en CD8+ sitokiene produksie getoon. Geen groot verskille is gesien in ander groepe nie. By CD4+ en CD8+ T selle was normale sitokiene produksie teenwoordig toe dit in vitro geaktiveer is om regulatoriese sitokiene produksie te produseer, wat beteken dat hul limfoïede komponent na oorplanting ongeskonde was. BEEN SIEKTE Beide die Dubbele energie x-straal absorpsiemetrie (DXA) en Kwantitatiewe rekenaar tomografie (QCT) is hier gebruik om been mineraal digtheid te evalueer. Daar was ʼn teenstrydigheid teenwoordig tussen die twee modaliteite. DXA het geen osteoporose getoon nie maar QCT het 22% getoon. Biomerkers was normaal in albei. Daar was geen geskiedenis van frakture en geen objektiewe bewyse van vertebrale frakture met Vertebrale Fraktuur Assessering nie. Alhoewel QCT gebruik is vir die studie bly DXA die goue standaard in Suid-Afrika. GEVOLGTREKKING Hierdie doktoraal verskaf inligting oor die nie-hematologiese gevolge in Suid-Afrika met die gebruik van Campath® ex vivo.

published_or_final_version / abstract / Orthopaedics and Traumatology / Master / Master of Philosophy

published_or_final_version / abstract / Mechanical Engineering / Master / Master of Philosophy

published_or_final_version / abstract / Medicine / Master / Doctor of Medicine

published_or_final_version / abstract / Medicine / Master / Master of Philosophy

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

Cellular proliferation is a key characteristic of hematopoietic stem and progenitor cells (HSC/HPCs) that allows for the production of all blood cell lineages during an individuals lifetime. While this feature of stem cells is strictly regulated during steadystate and stress hematopoiesis, it also contributes to the development of myeloproliferative disorders, such as chronic myelogenous leukemia, essential thrombocythemia, and polycythemia vera. It should come as no surprise then, that common treatments for these diseases often target the proliferative nature of the dysfunctional HSC/HPCs. Thus, the identification of molecular determinants of cell cycle regulation associated with these disorders could serve as targets for novel therapies. Using the hematopoietic system of the inbred mouse strains, C57BL/6J (B6) and DBA/2J (D2), it was found that the HSC/HPCs of the long-lived B6 mouse strain were less susceptible to the cytostatic agent hydroxyurea (HU) than the short-lived D2 mouse strain. A quantitative trait locus (QTL) analysis revealed a region of proximal chromosome 7 that regulates this response to HU. Congenic mouse strains were generated and phenotypic analysis confirmed that the B6 and D2 loci confer a low and high sensitivity of the HSC/HPCs to HU, respectively. We then showed that while this response of the HSC/HPCs to HU is independent of their cell cycle status, the B6 allele of this QTL confers a proliferative advantage to bone marrow cells after bone marrow transplantation. Having shown that proximal chromosome 7 regulates the response of HSC/HPCs to HU, we found it necessary to characterize the gene and protein expression profiles in order to identify the responsible candidate genes. We first analyzed mRNA expression profiles of HPCs from the parental and congenic mouse strains using gene microarrays and found that four genes within the congenic interval were differentially expressed. Real-time PCR confirmed that the expression profile of only one gene, Ndufa3, is significantly different in HPCs of B6 and D2 mice. Concurrently, we assessed the protein expression profiles of HPC-enriched mononuclear cells. Significant differences were found between the cytoplasmic and nuclear fractions of both strains, with a skewing of protein expression towards the D2 congenic strain.

The purpose of this project was to create a series of lessons that incorporate both Biology and Engineering concepts. The three lessons were intended to increase in complexity as the students progress throughout the year. Using PyMol software allowed students to visually represent complex protein structures while introducing and providing an opportunity to practice programming. Each lesson was followed by a worksheet or activity to aid in students' comprehension and application of practice. These lessons were designed to maximize students' time learning to program and using PyMol software while enhancing the current curriculum. Lesson one introduced students to the PyMol software while building and representing the four main structures of proteins. With increased programming knowledge, lesson two focused on modeling the DNA double helix. The final lesson introduced students to evolutionary relationships based on a protein's amino acid sequence. / text

Nanotechnology is an emerging field of engineering. Awareness needs to be fostered in the K-12 education system in order to sustain its expansion. As a current Algebra 1 teacher, I participated in the NASCENT research program to further my education in nanotechnology and find ways to integrate this content and practices in my Science Technology Engineering and Math (STEM) based Algebra 1 curriculum. During the research, I learned about surface tension of solids and liquids and its effects on materials' wetting properties. After completing the research program, I created a 2-week long project where students will replicate my experiences during this research. The purpose of this report is to investigate the need for the integration of nanotechnology in STEM classes and find ways to turn my research experience into real-world learning opportunities for my students. / text