3. Electronic Theses and Dissertations (ETDs) - All submissions

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    (1-3)-B-D glucan exposure assessment in poultry farms in South Africa
    (2015-04-13) Dayal, Payal
    Introduction: Poultry workers have an increased risk of respiratory symptoms associated with various irritant and allergenic exposures causing airway inflammation. This study investigated the levels of (1-3)-β-D glucan exposure in several poultry farming processes. The objectives involved categorising the different tasks undertaken in the poultry industry. After which a method was established and validated to detect and quantify the levels of (1-3)-β-D glucan using the Glucatell assay. This assay was used to measure the amount of (1-3)-β-D glucan poultry farm workers were exposed to using personal sampling. Thereafter, general respiratory symptoms were described briefly via the administration of a respiratory questionnaire. Method: A total of 308 personal air samples were collected from several poultry farming processes (rearing, laying, hatchery, broilers, catching) of a large poultry farm in the North West Province. A walkthrough checklist was used to obtain information on various exposure determinants such as farm size, number of chickens, ventilation system, bedding material used and poultry feed used. The Glucatell assay (Associates of Cape Cod, East Falmouth, MA, USA) was used to quantify the concentration of (1-3)-β-D glucans in the air samples. Results: The geometric mean concentrations of (1-3)-β-D glucans ranged from 24.38 to 645.98 ng/m3 across the various poultry farming processes investigated. Workers in the broiler farms were exposed to two times higher levels of (1-3)-β-D glucans compared to those in the breeding farms. The sizes of the broiler farm houses as well as the age of the chickens were among the main determinants of exposure. The larger broiler farm houses (GM=5.2 ng/m3, GSD=3.74) had significantly (p<0.05) lower levels than the smaller broiler farm houses (GM=6.4 ng/m3, GSD=2.14) whilst houses with older chickens had higher (1-3)-β-D glucan levels (G=5.8 ng/m3,
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    A 10 year evaluation of postpartum maternal mortality at Chris Hani Baragwanath hospital [2004 - 2013]
    (2016) Moletsane, Mabereng Matsepo
    This study examined postpartum maternal deaths at Chris Hani Baragwanath Hospital (CHBH) between January 2004 and December 2013. The aim was to gather reliable information about the trends and rates in postpartum maternal mortality which is important for resource mobilisation, planning and improvement in progress towards Millennium Development Goal 5 i.e. a 75% reduction in the maternal mortality ratio (MMR)from 1990 to 2015. The causes and predisposing factors to maternal deaths were scrutinised to identify factors involved in the stagnation of the MMR. The medical records of all mothers who died at CHBH during 2004-2013, as contained in the individual patient files were used as data sources. There were 409 maternal deaths out of 224 562 live births of which 261 were postpartum deaths. The MMR was 182 per 100 000 live births for the 10 years evaluated. The main causes of death were indirect causes, predominantly non-pregnancy related infections, with respiratory tract infection, mostly pneumonia and tuberculosis being the predominant contributing factors. It is recommended that all maternity units conduct, review and publish MMR in order to highlight and identify factors involved in the failure to reach the Millennium Developmental Goal i.e. a 75% reduction in MMR by 2015.Factors that are involved in the stagnation need to be more completely identified.
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    A 10 year review of idiopathic nephrotic syndrome in children: a single-centre experience, Johannesburg, South Africa
    (2016-10-12) Bakhiet, Yassir Mahgoub
    Background: Idiopathic nephrotic syndrome (INS) is the commonest type of nephropathy seen in children. The histopathological types and steroid response patterns of INS have been changing over the years and this has been attributed to differences in ethnicity and geographical location. The aim of this study was to determine the steroid response pattern, renal histopathology and complications in a cohort of the children treated for INS by the Division of Paediatric Nephrology, CMJAH, Johannesburg, South Africa between 2004 and 2013. Method: A retrospective study was carried out to review the records of 163 children between the ages of 2 and 16 years managed for INS over a 10 year period. Results: The majority (111) of the 163 children were of the black racial group. There were 97 boys and 66 girls. The mean age of onset was 5.3 years ± 2.8, with the highest rate of INS seen in the 2-6 year age group (71.2%). Only 132/163 had a renal biopsy performed (MCD 52.3%, FSGS 43.2%, MesPGN 4.5%). The black race had a similar rate of MCD (38.8%) and FSGS (37.8%), while the white race had a higher rate of MCD (64.3%) when compared to FSGS (14.3%). Ninety four (57.7%) patients were steroid sensitive (SSNS) while 69 patients (42.3%) were steroid resistant (SRNS). Minimal change disease was the most common histopathological type seen in SSNS (60%), while FSGS was the most common observed in patients who had SRNS (65.2%). There was a statistically significant association between the various steroid response patterns and the different histopathological types. The highest rate of resistance to all treatment after a mean follow up of 60 months was seen among children of the mixed race and black racial groups (50.0% and 40.5% respectively). Stunted growth (52.1%), hypertension (47.2%) and reduced eGFR (25.8%) were the most common complications observed. Conclusions: There appears to be an increase in the rate of FSGS in all the racial groups, and an increase in the rate of MCD in the black race group, when compared to previous South African studies. Furthermore, steroid response was also observed to have increased significantly among the black racial group when compared with previous studies. Although hypertension was the most common complication observed in our cohort, a very high rate of stunted growth was also observed. This may be due to the significant number of patients with reduced eGFR, SRNS and FSGS in our cohort. The use of long term steroid therapy may have contributed to this high rate.
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    A 10-year retrospective review on mob justice fatalities examined at the Germiston Forensic Pathology Medico-legal Service
    (2018) Medar, Sajida
    Mob justice fatalities are a gross violation of human rights in that they represent extra-legal punishment. There is a paucity of research relating to the demographics of at-risk groups, nature of injuries and the impact to the Forensic Pathology Service (FPS). This was a retrospective study over 10 years at Germiston Forensic Pathology medico-legal service. The objectives were to describe the demographics of the deceased, identify the profile of at-risk groups, describe the trends of the number of fatalities and causes of death over time, assess hospitalisation frequency, describe the nature and location of injuries sustained, and to report on ancillary investigations performed. Data was collected from the South African Police Service (SAPS) 180 scene investigation record form, hospital notes, final post mortem report, Notification of death (BI1663) form and additional statements. 354 cases were analysed. There was no clear trend in the number of mob justice fatalities. Six areas were highlighted to have a higher incidence of mob justice fatalities. The at-risk population was young to middleaged black South African males. The majority of deaths were due to blunt force head injury, and were so severe that most deaths occurred within 24 hours of injury. A standardised operating procedure should be developed for uniformity in managing mob justice cases. Adequate resources should be distributed to appropriate departments to enable a reasonable turnaround time of ancillary investigations and high incidence areas should receive sufficient and appropriately skilled resources to engage with and monitor the respective communities to curb these killings.
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    "100 papers": an anthology of flash fiction and prose poetry with a theoretical postscript
    (2008-05-30T07:24:40Z) Jobson, Liesl Karen
    [NO ABSTRACT PRESENT]
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    The 1989 black matriculation failure rate : what were the classroom practices?
    (1994) Zimba, Maoto David
    This research is an attempt to reveal aspects of History teaching concealed in conventional or popular beliefs about the Black Matriculation pass/fail statistics. The classroom practices of two History teachers are described. One comes from an "achieving" Soweto secondary school. The school is popularly contrived as an "achieving" school because it is known in the community for producing better than average DET Matriculation results. The classroom practices of another teacher. from an "underachieving" school. are also described. This school is known in the community for producing lower than average DET results over a number of years. These classroom practices are illuminated against the backdrop of the high pass/low failure rate during the eighties, with particular reference to the year 1989. This is the year in which the DET matriculation pass/failure rate was the worst in the decade of the eighties. (Abbreviation abstract)
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    The 2011 humanitarian intervention in Libya: from just intervention to just peace?
    (2017) Mokwele, Tshepho Joseph
    This research report analyses the 2011 humanitarian intervention in Libya and seeks to establish whether or not it was morally justified and if it led to a better state of peace (a just peace). It analyses the intervention through the prism of just war theory and the responsibility to protect (R2P) doctrine. Just war theory and the R2P doctrine provide moral guiding principles that must be met to justify the resort to war, its conduct and termination. These principles are outlined in just war theory as jus ad bellum, jus in bello, and jus post bellum. The report highlights the origin and evolution of just war theory vis-à-vis to the practice of humanitarian intervention. Humanitarian intervention has long been prohibited by established international law which, nevertheless, provides for the protection of fundamental human rights. Ingrained in international law are the Westphalian principles of state sovereignty and non-interference that have created a tension between the rights of the states and those of individuals. While international law explicitly states that countries have the right to individual or collective self-defence, it implicitly advocates for humanitarian intervention where a state is unable or unwilling to protect its people. The study, therefore, adopts the notion of sovereignty as responsibility as revived by R2P. It holds that every state ultimately derives its rights from those of individuals: the former forfeits its rights when and if it violates those of the latter. In such a case, a state loses its sovereign standing and becomes liable to humanitarian intervention. The decline in interstate conflicts and the rise of intrastate conflicts since the end of the Cold War reignited the debate around the legality and legitimacy of humanitarian intervention because no universally accepted enabling framework has hitherto existed. But in 2001, the International Commission on Intervention and State Sovereignty (ICISS) published the R2P report that serves as a generally accepted framework for humanitarian intervention today, following its unanimous endorsement by states at the UN World Summit in 2005. This study, however, that while the ICISS R2P is broad and encompasses the responsibilities to react, prevent, and rebuild, the UN R2P is narrow and lacks the post-war reconstruction element. But this is not new: the jus post bellum element of just war theory has historically received little attention in the literature, which has affected its practice. A similar trend is developing with the R2P and the case of Libya is illustrative of that. The study’s application of just war theory and R2P propositions to the Libyan situation establishes that the intervention was morally justified for it prevented the massacre of Libyans by the Qaddafi regime but did not lead to a better state of peace mainly because it was not followed up with post-intervention reconstruction. Failure to consider post-intervention reconstruction in Libya, however, does no damage to the practice of humanitarian intervention. Rather, it serves as a lesson from which to learn and indicates that jus post bellum is integral to just war theory just as the responsibility to rebuild is to R2P in theory and practice.
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    The 2018 conceptual framework: an investigation of evidence of neoliberalism and stewardship in submitted comment letters
    (2020) Van Wyk, Janey
    This paper investigates the level of propensity for either a neoliberal or stewardship paradigm which may be prevalent in the comment letters addressing the 2018 Conceptual Framework Revision project. Previous research explored the two paradigms, namely, the neoliberalism and stewardship paradigms evident in accounting and the impact of isomorphism on the views stakeholders hold. This study will seek to indicate the level of consensus among the key stakeholders identified in the paradigm in the Conceptual Framework and the resulting expectation of its perceived legitimacy in financial reporting around the world which has not yet been addressed in previous research. This paper also focuses on whether the stakeholders of financial statements are more inclined toward either paradigm, irrespective of which jurisdiction they may belong. This research adopts a cost-effective methodology by utilising existing data available in the comment letters as the source of data for this study. The key objective is to understand what direction the interested stakeholders recommend the Conceptual Framework should take as the Conceptual Framework has a direct impact on the formulation of existing and future accounting standards
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    A 21-year retrospective histopathological evaluation of cysts and tumours associated with impacted teeth
    (2018) Mohammed, Muhanad Hashim Salman
    Background Odontogenic cysts and tumours may be observed in association with impacted teeth. There are no published reports on the histopathological characterisation of cysts and tumours associated with impacted teeth in South Africa. This study aims to determine the relative frequencies and the clinico-pathological features of these lesions in a South African population sample, and to compare the data with information available in the literature. Methods The histopathology records of all specimens associated with impacted teeth were collected over a 21-year period from 1996 to 2016 from the files of the Department of Oral Pathology, School of Oral Health Sciences at the University of the Witwatersrand. Clinical data and histological diagnoses were reviewed and analysed. Results Out of a total of 24,542 pathology specimens, 407 (1.7%) specimens were associated with impacted teeth in 390 patients. Pathological lesions were diagnosed in 389 (95.6%) cases while 18 (4.4%) specimens represented non-pathological dental follicular tissue. The median patient age was 24 years (3-88 years) with males accounting for 64.9% of the patients. The 11-20 year age group showed the highest overall frequency of pathological lesions associated with impacted teeth, while the 41-50 year age showed the lowest frequency. Dentigerous cyst was the most commonly diagnosed lesion accounting for 63.4% and 43% of all lesions v diagnosed in males and females respectively. No significant association was found between the age of the patient and the biological potential of lesions associated with impacted teeth. Conclusions The frequency of histopathological diagnoses associated with impacted teeth significantly reduces with an increase in age. The findings of this study show similar trends to some previously published reports from other geographic areas. The information gathered in this study provides a local data base of the frequencies of odontogenic cysts and tumours associated with impacted teeth which may assist clinicians in formulating differential diagnoses.
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    27 April 2022 in Johannesburg The ‘original sin’ hypothesis and the evolution of programmed cell death en route to eukaryogenesis
    (2022) La, SoRi
    Programmed Cell Death (PCD) genetic toolkits and mechanisms of death in prokaryotes, particularly archaea, are poorly understood and whether PCD mediated conflict in eukaryogenesis remains controversial. This study aimed to investigate C14 peptidases, the key effectors of PCD, in archaea and their evolutionary histories prior to eukaryogenesis. Their wide taxonomic distribution and phylogenetic reconstruction revealed that C14 peptidases were present before the divergence of prokaryotes. Furthermore, phyletic pattern and death domain architecture analyses revealed that they were likely associated with pro-survival functions before their co-option in PCD, supporting Ameisen’s ‘original sin’ hypothesis for PCD origins. In vivo analysis to explore potential caspase- and metacaspase-like activity in Halobacterium salinarum under oxidative stress showed negative results, in accordance with PCD being a black queen trait in the microbial loop between H. salinarum and Dunaliella salina. This study provides a detailed evolutionary history of C14 peptidases prior to eukaryogenesis.
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    3-Dimensional reconstruction of the breast tumour microenvironment: mediation of tumour progression by T(REG) lymphocytes and NK cells
    (2015-04-21) Augustine, Tanya Nadine
    Breast tumour progression involves complex interactions between malignant cells and the tumour microenvironment. It is increasingly apparent that immunity is a critical determinant for tumour progression. T regulatory (TREG) lymphocytes, which dominate tumour infiltrating lymphocyte populations, are implicated in facilitating tumour immunoediting processes and suppressing Natural Killer (NK) cell anti-tumour function. To investigate such cellular interaction, experimentation traditionally involves using reductionist 2-dimensional culture systems that do not recapitulate the spatial dimensions of the in vivo microenvironment. Three-dimensional (3D) culture systems, conversely, recreate these dimensions, allowing tumour cells to assume a phenotype more representative of the tumour microenvironment. Given that immunity is a critical factor in determining tumour progression, a novel 3D culture system was established to investigate the interactions between TREG lymphocytes, NK cells and hormone-dependent (MCF-7) or hormone-independent (MDA-MB-231) breast cancer cells. Lymphocyte subpopulations were magnetically isolated, with the efficacy of the sorting procedure verified using flow cytometry. To generate 3D cultures, cell populations were resuspended in growth factor-reduced Matrigel and cultured for 72 hours. This culture system proved effective for RNA extraction for downstream applications; for immunolocalisation of selected tumour biomarkers (ER-α, TGF-β, MUC-1 and EGFR) for qualitative analysis; and for acquisition of cytokine data (IL-1β, IL-2, IL-6, TNF-α, IFN-, CCL2, CCL4 and CXCL8) for quantitative multivariate statistical analysis. Immune mediation was shown to induce the disruption of cell-cell associations, altering the expression of biomarkers and secreted cytokine profiles. Collectively, these results reflect tumour cell subversion of NK cell and/or TREG lymphocyte function to promote tumour progression by generating an inflammatory microenvironment. While hormone-dependent and hormone-independent breast cancer cells differed in their specific response to immune mediation, the mechanisms by which they elicited responses resulted in similar outcomes – that of enhanced evasive and invasive capacity. It is necessary to further elucidate the relationship between the investigated cytokines, biomarkers and immune cells, to understand their interactions and potentially provide more information for therapeutic intervention, given that these factors may contribute to tumours not responding favourably to combined modalities of therapy.
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    37 kDa LRP::FLAG enhances telomerase activity and reduces ageing markers in vitro and in vivo
    (2020) Otgaar, Tyrone C
    Ageing is a degenerative process characterised by detrimental changes which accumulate to cause a decline in physiological functioning of the organism. It is characterised by stem cell exhaustion, mitochondrial dysfunction as well as genomic instability. One of the core regulators of cellular ageing are telomeres, repetitive DNA sequences of TTAGGG that cap the ends of chromosomes and are maintained by the ribonucleoprotein DNA polymerase complex, telomerase. Age-dependent progressive loss of telomere functions due to the “end replication” problem and insufficient telomerase activity eventually induces cell cycle exit for the induction of either replicative senescence or apoptosis. To bypass senescence, most epithelial and tumorigenic cells re-activate telomerase allowing for telomere extension thereby, extending their proliferative potential and promoting overall cell viability. It was recently established that knockdown of the 37kDa/ 67kDa laminin receptor (LRP/LR), a proliferative-related protein which maintains cell viability in cancerous and normal cells, reduces telomerase activity. Therefore, it was hypothesized that elevating LRP/LR may increase telomerase activity and hinder the ageing process. The core aims of this research included: To prove in vitro that LRP::FLAG overexpression influences telomere dynamics and senescent related proteins in cells. Thereafter, to prove in vivo that LRP::FLAG overexpression (i) has an effect on the ageing process, (ii) positively impacts on telomere dynamics and (iii) significantly reduces the levels of tissue senescence in aged C57BL/6J mice. To this end, cell lines were successfully developed that stably overexpressed LRP::FLAG and have further overexpressed LRP::FLAG in aged C57BL/6J mouse models. Western blotting, confocal microscopy and qPCR were used to assess the effects of overexpression of LRP::FLAG on ageing markers as well as telomere dynamics in both cell lines and mice. In addition, various physiological tests (balance beam, puzzle box, nesting, wirehang, social interaction, open field and hair greying tests) and histological analyses were performed to assess overall mouse fitness as well as to discern the treatments ability at reducing tissue degeneration and atrophy. In terms of the in vitro research, it was found that the overexpression of LRP::FLAG induced a significant elevation hTERT levels, telomerase activity and telomere length. Concomitantly, it was shown that LRP::FLAG overexpression also reduced the levels of the senescence/ageing markers β-galactosidase and λH2AX in both HEK293 and MRC 5 cells. Moreover, for the in vivo component it was found that mice overexpressing LRP::FLAG displayed improved physiological characteristics and markedly less tissue degeneration and atrophy when compared to control and non-treated mice. Alongside these improvements, certain organs displayed increased telomerase activity with a corresponding elongation in average telomere length, further substantiating that a functional relationship exists between LRP and telomerase. In addition to the improved aspects of telomere biology it was found that the overexpression of LRP::FLAG significantly improved various proliferative and anti-ageing associated proteins (Klotho, MDM2, SIRT1, Akt and c-Myc) while causing a concomitant decrease in senescent associated proteins (p16, NFkB and γH2AX). These findings are indicative of a novel function of LRP/LR impeding the onset of senescence, while also promoting healthier ageing through elevating TERT and telomerase activity. Therefore, LRP::FLAG could act as a novel drug for healthier ageing through the impediment of the cellular ageing process
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    3D animation as a medium of cultural representation and education : a case study of Magic Cellar part 1.
    (2011-05-03) Kangong, Roland N.
    Post-apartheid South African children are exposed to modern technological entertainment – television, cell phones, video games, TV animations and many other forms of popular art and media. This research report analyzes how well Magic Cellar (hereafter referred to as MC) both represents cultural diversity to a mixed audience of South African children from different ethnic backgrounds and cultures, and educates them more generally. A historical perspective on animation is provided, including animation in South Africa, as well as the technical processes of animation, and how these apply to MC. In so doing, answers to two main questions are sought: can 3D animation be used as an alternative or support to the school classroom in educating children through popular media forms? To what extent can 3D digital art technology in the form of animation be used in representing cultural diversity to children of different cultural backgrounds? Drawing on theoretical concepts, as well as comparing MC to successful programming for children that uses animation to educate, this research report argues that 3D animation, a medium that “seems to attract learners’ attention and increase their motivation to learn”(Khairezan 2), can be used to represent cultural diversity and to educate children.
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    A 3D approach to understand the taphonomy of the early Hominins from the Plio-Pleistocene cave site of Malapa
    (2014-01-06) Val, Aurore Marie Sophie
    The cave deposits at Malapa, on the Malapa Nature Reserve, Cradle of Humankind World Heritage Site, Gauteng Province, South Africa, have yielded the remains of two extremely well-preserved hominins (Australopithecus sediba) and associated fauna, dated by U/Pb methods and palaeomagnetism to 1.977-1.8 Ma. The state of preservation of the hominins and some of the non-hominin material, characterised by complete and near complete elements, antimeric sets of bones, specimens in articulation, and well-preserved bone surfaces, is remarkable in the context of Plio-Pleistocene fossil assemblages accumulated in caves, and indicates a unique combination of taphonomic processes, not yet observed in contemporaneous cave deposits in the region. A comprehensive approach, including palaeontological, physical, and spatial analyses of the hominins and associated fauna was undertaken to determine, describe and interpret the taphonomy of the faunal material, with particular reference to the holotype and paratype of Au. sediba, Malapa Hominin 1 (MH1) and Malapa Hominin 2 (MH2). An innovative combination of Computed-Tomography (CT), micro-CT scanning and virtual reconstruction techniques was applied to create a 3D model of a selected area of the Malapa cave, with renderings of the two near-complete Au. sediba skeletons. The original burial position of the hominins was reconstructed, which necessitated the refitting of ex situ fossils into in situ deposits. The spatial distribution and orientation of the hominin remains illustrate a very low degree of dispersal of the bones, indicative of very little disruption between death and burial, due to an absence of damage by scavengers and possible natural mummification. The very few carnivore-damaged bones and relative abundance of complete and/or articulated specimens, the presence of antimeric sets of bones in the faunal assemblage, as well as the diversity of the faunal spectrum, and the significant percentage of animals with climbing proclivities (such as carnivores and hominins) indicate that the majority of the faunal material recovered was most likely accumulated via a natural death trap. Their bodies came to rest in a deep area of the cave system with restricted access to iii scavengers. Skeletons and bones accumulated in a talus cone below a vertical shaft. There, they decomposed, and became buried without major disruption by biotic or abiotic agents. A new forensic approach, referred to as palaeoforensic taphonomy, was followed in each step of the taphonomic analysis of the two hominins in order to reconstruct the processes of decay, disarticulation, burial and preservation. Results show that both individuals did probably not enter the cave system at the same time. They reached skeletonization and were slightly weathered before final burial, indicating several years of exposure before burial. Insects proved to be the primary modifiers of the hominin remains, pre- and post-depositional with hide beetles (Omorgus squalidus) providing the closest match for some of the fossil modifications observed. Based on the high number of articulated remains, the absence of preferential orientation for the elongated bones and of significant movement of the hominin remains inside the deposit, the debris flow hypothesis that was previously proposed as the principal agent to explain the burial of the hominins and other well-preserved animals is challenged. Evidence of natural mummification before burial for MH1 and MH2 suggests the possible preservation of soft tissue. The innovative 3D techniques applied in this research to conduct the spatial analysis of the fossils proved useful to address taphonomic questions, and will serve as a guide for future excavations of the Malapa in situ deposits, especially for locating the missing skeletal elements of MH1 and MH2.
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    3D geological modelling and mineral resource estimate for the FE2 gold deposit, Sadiola mine, Mali
    (2016-04-05) Chanderman, Lisa
    The FE2 Gold Deposit forms part of Sadiola Mine located in south-western Mali - nearby the border with Senegal - approximately 440km north-west of the capital Bamako, and 70km south of the city of Kayes. Sadiola Mine is made up of 7 open pits (the Main Pit, FN3, FE2, FE3, FE4, Tambali and Sekokoto). Gold (Au) mineralisation is spatially associated with a complex alteration pattern, pointing to a mesothermal origin for the Au mineralisation. The Main Pit deposit contains an Oxide portion and a deeper Sulphide zone comprised of unweathered material below the pit. In 2010, mining of the Oxide portion was concluded. Currently, Sadiola does not have the plant capability to treat Sulphides due to its hardness and most of the Oxide Mineral Reserve in the concession has been depleted. The FE2 deposit is expected to provide Oxide Ore for 7 months based on the current mine plan. The Oxide mining on the Sadiola concession has an expected life of 3 years. Sadiola’s future is thus tied to the fate of the Sadiola Sulphides Project (SSP), targeted at exploiting the Sulphide zone Ore. In the absence the SSP materialising to date, focus has shifted to the FE2 deposit to scavenge any remaining Oxide Ore, to prolong mine life. The previous Mineral Resource model was generated in June 2014. The model was based on grade control drilling information. The current Mineral Resource Estimate (MRE), presented in this research report, was prompted by an Advanced Grade Control (AGC) drilling campaign that took place during October 2014 to identify additional Oxide Ore Mineral Resource (Indicated, Inferred and Blue Sky Potential). The AGC drillholes (12.5m (X) by 12.5m (Y) drill spacing) have been drilled mostly as infill drilling and all holes had accompanying assay data. The Ore and Graphite mesh modelling was conducted using the grade interpolation technique in Leapfrog® mining software. The Hardness, Redox, Laterite and Classification wireframes were created in Datamine® Studio 3 software. A lower geological cut-off of 0.32g/t Au was applied to the mineralised domains. Three domains were estimated: EZONE 1 (Laterite and Saprolite Ore); EZONE 2 (Hard Ore i.e. Sulphides) and EZONE 3 (Waste). All estimation into the Mineral Resource model was done in Datamine® Studio 3. Ordinary Kriging (OK) was used to estimate the Au grades; Inverse Power of Distance (IPD) to estimate “hardness probabilities” for isolated hard/blastable material above the hard/soft contact; and Indicator Kriging (IK) used to estimate the distribution of the Graphitic alteration. The Au estimation process was optimised using Quantitative Kriging Neighbourhood Analysis (QKNA). The estimates were validated visually, statistically and using swath analyses. Uniform Conditioning (UC) was used to estimate the recoverable Mineral Resource in EZONES 1 and 2 for the reporting of the distribution of grades above various economic cut-offs. The Selective Mining Unit (SMU) size assumed for the FE2 UC process was 10m (X) x 10m (Y) x 3.33m (Z) and was based on the selectivity achievable with the current mining equipment. Given the panel size of 25m (X) x 25m (Y) x 10m (Z), there were about 18 SMUs in each panel. A tonnage adjustment factor was applied and was based on a volume representing half the SMU size. It was expressed as a percentage of the panel size (2.7%). Any proportions smaller than this percentage were removed as they would not be practically recoverable (these volumes would be too small to mine with the selected equipment). The Mineral Resource was classified in accordance with the South African Code for Reporting of Exploration Results, Mineral Resources and Mineral Reserves (SAMREC) and the Australian Joint Ore Reserves Committee (JORC) guidelines. A drill spacing of 25m (X) by 25m (Y) was considered sufficient to classify the Mineral Resource as Indicated, and 50m (X) by 50m (Y) as Inferred. Areas covered by larger drill spacing were considered to be Blue Sky Potential (not an official Mineral Resource Category, but used for internal purposes by AngloGold Ashanti Limited (AGA) to estimate possible mineralisation potential). No Measured Mineral Resource was defined. The classification criteria are based on studies completed for other, similar Sadiola deposits (such as FE3 and FE4). The 2014 Mineral Resource model was compared with the updated Mineral Resource model (2015) within a common volume i.e. within the Business Plan (BP) 2015 $1,600 Mineral Resource shell and the $1,200 Mineral Reserve design (below the topography as no mining has taken place at FE2) to quantify if the Oxide Ore potential had increased as a result of the model update (Table 1). The detailed Reconciliation study showed that the new estimate identified an additional 7,191 ounces of Indicated Mineral Resource – of which, 1,893 ounces was previously classified as Inferred Mineral Resource but was upgraded to the Indicated Mineral Resource category as a result of the new Mineral Resource model. The reason for the increase is due to the new drilling results which resulted in the extension of some of the mineralised zones and showed better continuity for others. Table 1:Model reconciliation by broader material types: 2014 vs. 2015 MW cut-off grades.A checklist of assessment and reporting criteria based on the JORC code showed that no major risks to the model exist. However, some key recommendations were made and include: - Testing domaining and variography at various geological cut-offs - Performing an updated Classification study to confirm the suitability of the Classification criteria used - Soft Oxide density probe measurements reported in 2015 were significantly higher than in 2014. Further work needs to be done to confirm the validity of the density results before updating the 2015 density values - Testing estimation software used in the estimation process against similar software in the industry to single out the one that provides the most accurate results - Further work should be carried out to assess the effect of top cuts and top caps on the resulting Mineral Resource models - Further work is required on boundary analysis going forward as in reality the Laterite and Saprolite are very different, despite the results of the statistics suggesting that they are similar. - The latest LIDAR survey had not been provided at the time of Ore wireframe modelling. A new survey needs to be carried out to ensure that drillholes collar positions used in the modelling were correct - Further work is required to understand what method is best to model the extent of the graphitic alteration and how to optimise the method
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    3D geophysical modelling of the Bethlehem sub-basin, Free State, South Africa
    (2020) Naidoo, Ansuya
    Extensions to the Witwatersrand Basin have been widely examined, with many geophysical surveys being carried out in the early 1990s. One of these areas is the Bethlehem sub-basin, located on the south eastern edge of the Witwatersrand basin. The aim of the study is to integrate old geophysical datasets to create a 3D geological and a 3D gravity forward model of the Bethlehem Sub - basin. A re – interpretation of the Bethlehem sub-basin was done using the latest geophysical software and techniques. The study also investigates the cause of the Bethlehem gravity high. The outcome of this study provides a more constrained interpretation of the structure of the Bethlehem sub-basin and its relationship to the Witwatersrand Basin. The resultant 3D gravity model shows the Bethlehem Sub - basin is structurally controlled by north northwest trending horsts and grabens of granite and West Rand Group rocks respectively. These grabens preserve large-scale West Rand Group sediments of the Witwatersrand Supergroup. The horst and graben structures creates a change in density from low density granite to high density West Rand Group, causing the gravity high seen in the Bethlehem area. Four major structures were interpreted in the seismic and gravity data. These are labelled as fault B, C, D and E. Normal faults B and C trending north northwest create a granite ridge underlying the Karoo Supergroup. Normal faults D and E create a smaller granite ridge overlain by West Rand Group sediments. This study investigates the ability to integrate existing 2D datasets into a 3D space and the significance of viewing data in a 3D environment to better understand and constrain lithological structures and boundaries
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    3D geophysical modelling used for structural interpretation in southern Mali and northeastern Guinea, West Africa
    (2017) Yossi, Mamadou
    This study presents the combined processing, integration and inverse modelling of magnetic and gravity data for first-order crustal scale structures in southern Mali and northeast of Guinea. Southern Mali and northeast Guinea form part of the Palaeoproterozoic Baoulé-Mossi domain, which is part of the West African craton (WAC). The current understanding of the geology region is limited to exploration camp-scale studies with limited borehole investigations, and regional interpretations of historic geophysical datasets. In this study geophysical modelling is used to attempt to advance the understanding of the geology at depth. The combination of geophysical methods is an optimization that can support geophysical interpretations and contribute to the determination of the geological and structural characteristics that are important in understanding the subsurface geology. Geophysical inversion modelling broadly resolved geology and structures under thick sedimentary cover (850-1100, thick) that is interpreted as comprising basinal sediments of the Taoudenni basin, or Cretaceous ferricrete. Geological constraints reduced the non-uniqueness, but could not control the quality. Nonetheless, the architecture, geometry and form of structures and dykes were predicted when compared with experimental analogue models as being a reasonable predictive tool for the behaviour of structures and dykes at depth. The use of surface physical properties added more information to the inversion modelling, but was very limited. The enhancement of magnetic and gravity data, using filters, defined tip damage zones for firstorder scale Yanfolila and Banifing shear zones that host gold mineralisation for example, at the Morila gold mine, and Kalana, Kodieran mines and Komana prospects. Second-order structures were also defined including in the tip damage zones of the Siguiri, Fatou and Syama shear zones, and the Manakoro fault, Madina-Yanfolila fault and Madina fault.
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    3D printed, artificial extracellular matrix for potential neuroregeneration
    (2021) Da Silva, Kate
    Traumatic Brain Injury (TBI) is a complex, heterogeneous injury ranging in severity and clinical outcomes. TBI is characterised by various stages of brain damage. The primary injury causes mechanical injury to the brain whereas the secondary injury results in further damage from molecular cascade responses. Despite great strides in knowledge and research, no significant improvement in TBI treatments has occurred to date. As this injury affects a significant portion of the population, it is prudent for research to be dedicated towards the development of an effective treatment. Artificial Extracellular Matrix (aECM) hydrogel scaffolds are gaining in popularity due to their inherent ability to provide a microenvironment similar to the in vivo microenvironment. Since the Extracellular Matrix (ECM) is directly implicated in scar formation, the fabrication of an aECM scaffold to prevent early glial scar formation in TBI may provide the much needed therapeutic strategy in potentially regenerating affected neurons. It is postulated that if intervention can occur soon after injury, ECM manipulation of the injury site can occur, which may promote native functioning and lead to functional recovery. With the drive towards patient customisable treatments, 3D printing is becoming an indispensable fabrication tool. Despite the advancements in 3D bioprinting, 3D biomaterial development for neural tissue engineering is hindered due to the numerous material requirements which need to be satisfied. This study aimed to investigate and design the proposed concept of a 3D printable hydrogel peptide aECM as a novel strategy for the treatment of TBI. An initial study into material selection for hydrogel 3D printing identified Gelatin Methacryloyl (GelMA) and a combination of collagen and elastin, as the material candidate for biomaterial development. Further optimizations saw the inclusion of Genipin into the biomaterial and resulted in the realization of the potential formation of a semi and full Interpenetrating Polymer Network (IPN). Thermodynamic results confirmed the formation of the two IPN biomaterials since the endothermic peak of the semi IPN and full IPN occurred at 140.59 °C and 168.18 °C, respectively indicating the increased thermal stability of the full IPN system. Thermogravimetric Analysis (TGA) indicated that the main loss of weight occurred between approximately 175 ˚C - 475 ˚C and approximately 200 ˚C - 500 ˚C for the semi IPN (64% weight loss) and full IPN (67% weight loss), respectively. Molecular vibrations analysis indicated that two minutes of Ultra Violet (UV) crosslinking did not affect the Amide peaks of the biomaterial IPN systems as the Amide bands are still intact with similar transmittance intensities. Therefore, no alteration to the peptide secondary structure was noted. Both IPN biomaterials were further shown to be amorphous in nature with a high Full Width at Half Maximum (FWHM) value of 7.82 and 7.67 for the full IPN and semi IPN, respectively. The IPN biomaterials have a stiffness of around 600 Pa and are suitable for softer tissue engineering applications – i.e. the brain. Furthermore, viscoelastic studies for all samples indicate that G’>G’’ and demonstrates that the hydrogels are more “solid” in nature. Furthermore, the semi IPN displayed the highest elasticity followed by the GelMA polymer and then the full IPN. In addition, both IPN biomaterial scaffolds displayed a “shape memory” feature in artificial cerebral spinal fluid (aCSF). Scanning Electron Micrographs indicated that the IPN biomaterials had a morphological structure with a significant resemblance to the native rat cortex. Both IPN scaffolds exhibited an increased biodegradation rate of 8 and 6 days, for the semi IPN and full IPN, respectively. The full IPN exhibits 1.5 times greater fluid uptake ability than the semi IPN and after 8 hours, the semi IPN and full IPN had a fluid uptake of 483.0 % and 725.6 %, respectively, in comparison to their initial dry masses. Both biomaterial scaffolds were shown to support the growth of PC12 cells over a 72-hour period. Furthermore, the increased nuclear eccentricity and nuclear area was shown to support the postulation that the IPN biomaterials maintain the cells in a healthy state encouraging cellular mitosis and proliferation. In addition, through fluorescent cell tracking, cellular migration was observed throughout the IPN biomaterial scaffolds. The Genipin component of the full IPN was further shown to exhibit antimicrobial properties in microdilution assays followed by the determination of the minimum bactericidal concentration. This suggests that Genipin can prevent the growth of pathogens associated with post-surgical brain infections. This research therefore contributes to the collection of potential biomaterials for TBI applications. Lastly, 3D printing coupled with the two novel biomaterials can assist in the progression of neural treatments towards patient specific scaffolds through the development of Custom-Neural-Scaffolds (C-N-S) as no two brain injuries are the same. In conclusion, the two biomaterial scaffolds developed in this research demonstrate potential for neuroregeneration in new TBI cases
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    3D toro-poloidal implantable device for the controlled delivery of rivaroxaban
    (2024) Mavuso, Simphiwe Valentia
    Implantable drug delivery devices offer many benefits over other routes of drug delivery. Most significantly, the potential of reducing systematic side-effects and improving patient compliance as drugs are delivered in lesser doses over an extended period. The present work was focused on designing a novel polymeric blend through a judicious combination of polymers. Polymeric material was used for the fabrication of implantable drug delivery devices (IDDDs) with varying geometrical considerations viz. torus and cylinder for the controlled delivery of a model antithrombotic agent, rivaroxaban (RXB). RXB is an antithrombotic drug used primarily for the prevention of stroke and systemic embolism in the general population of patients with thromboembolic disorders. Even though RXB is often a preferred anti-thrombotic it is associated with some degree of gastrointestinal (GI) bleeding, which is the most common extracranial haemorrhagic complication in patients on oral RXB. This 3D implant formulated is expected to offer an alternative route bypassing the gut, more convenient and safer for RXB delivery especially during long-term use, this device may be widely applied over a range of diseases requiring long-term use of a specific drug. A polyurethane (PU), polyethylene glycol (PEG) and Poly (lactic-co-glycolic acid) (PLGA) blend was used to load the RXB, while hydroxypropyl methylcellulose (HPMC) was used as a supporting material due to its gelation properties. Extrusion and compression-based methods were both utilised for the formulation of the 3D toro-poloidal (RXB loaded PU-PEG-PLGA/HPMC) implantable devices. The RXB loaded PU-PEG-PLGA/HPMC was then characterised using different physicochemical methods such as Fourier-Transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA) studies, all revealing the chemical and compatibility of the formulated components. For comparison 3D porous and nonporous donut shaped implants were also fabricated using compression method. Lastly in-vitro Factor Xa (FXa) assay, in-vitro release profiles, cytotoxicity, and in-vivo drug release studies using New Zealand White Albino rabbits were carried out. The 3D toro-poloidal implantable devices were successfully formulated and characterised using FTIR, PXRD, DSC and TGA, where analysis confirmed the formation of the RXB loaded and HPMC/PU-PEG-PLGA blends, also evident is that the individual structures of the innate polymers were only blended and not altered. Cytotoxicity studies using MTT assay showed no toxicity signs and the FXa activity increased with the increase in RXB concentration. The porous RXB showed much more drug released compared to the non-porous, while both geometries showed controlled sustainable drug release profiles suitable for delivery of potent drugs applied in small doses such as the RXB. The cylinder released the RXB at a constant rate while the donut released the RXB at a consistently increasing rate, both within the therapeutic range. The devices were observed to be having a biphasic release pattern, where an initial burst release was followed by a controlled extended drug release, with an initial burst release and a sustained release from 72 h to day 49. Approximately 97% and 89 % RXB was released on day 49 for donut implants, while only 61.3 % and 66.1 % of the RXB was released from the cylinder, the release was from compressed and extruded 3D implants, respectively. In both the in-vivo and in-vitro RXB release profiles the conventional oral RXB had a bioavailability lower by ±40% and ±32% for in-vitro and in-vivo, respectively, compared to the toro-poloidal 3D implant devices. Correlation of the cytotoxicity and RXB release studies was seen with the in-vitro relative to the in-vivo studies. In conclusion, the 3D toro-poloidal, 3D RXB loaded PU-PEG-PLGA/HPMC implant, has a great potential for personalised medicine, as these devices can be modified into different geometries with different release properties, suitable for both systematic and local drug delivery while avoiding the gut system.
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