Browsing by Author "Tshibalanganda, Muofhe"

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    Advancing X-ray micro computed tomography in Africa : going far, together
    (Elsevier, 2019) Du Plessis, Anton; Le Roux, Stephan G.; Tshibalanganda, Muofhe
    X-ray micro computed tomography (microCT) is a high resolution non-destructive materials imaging technology and is emerging as a powerful tool for industrial and scientific research applications. The aim of this review paper is to present the capabilities and potential of this technique within an African context. This is done using a representative sample: all work done at the Stellenbosch CT facility during 2018 is used as an overview of the type of work done at such a facility in Africa. Besides the plethora of academic research topics, the most important industrial applications are also discussed, which assisted to keep the Stellenbosch CT facility financially operational. This provides a wider understanding of the opportunities and capabilities of this technique and how it can benefit African researchers and local industries. The question “what is it used for?”, and more specifically “what is it used for in Africa?” is therefore answered. The availability of such X-ray tomography facilities helps to fast-track research by providing local expertise and support in Africa for advancing African science. This model is not only applicable to microCT but applies to any collaborative scientific endeavor in Africa, with success rates depending on the efficient sharing of resources, providing expert skills and advancing African science in Africa. There is an African proverb “if you want to go fast – go alone; if you want to go far – go together”. Clearly, African science will go far by working together in such facilities.
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    Gold exploration in two and three dimensions : improved and correlative insights from microscopy and X-Ray computed tomography
    (MDPI, 2020) Chisambi, Joshua; Von der Heyden, Bjorn; Tshibalanganda, Muofhe; Le Roux, Stephan
    Abstract: In this contribution, we highlight a correlative approach in which three-dimensional structural/positional data are combined with two dimensional chemical and mineralogical data to understand a complex orogenic gold mineralization system; we use the Kirk Range (southern Malawi) as a case study. Three dimensional structures and semi-quantitative mineral distributions were evaluated using X-ray Computed Tomography (XCT) and this was augmented with textural, mineralogical and chemical imaging using Scanning Electron Microscopy (SEM) and optical microscopy as well as fire assay. Our results detail the utility of the correlative approach both for quantifying gold concentrations in core samples (which is often nuggety and may thus be misrepresented by quarter- or half-core assays), and for understanding the spatial distribution of gold and associated structures and microstructures in 3D space. This approach overlays complementary datasets from 2D and 3D analytical protocols, thereby allowing a better and more comprehensive understanding on the distribution and structures controlling gold mineralization. Combining 3D XCT analyses with conventional 2D microscopies derive the full value out of a given exploration drilling program and it provides an excellent tool for understanding gold mineralization. Understanding the spatial distribution of gold and associated structures and microstructures in 3D space holds vast potential for exploration practitioners, especially if the correlative approach can be automated and if the resultant spatially-constrained microstructural information can be fed directly into commercially available geological modelling software. The extra layers of information provided by using correlative 2D and 3D microscopies offer an exciting new tool to enhance and optimize mineral exploration workflows, given that modern exploration efforts are targeting increasingly complex and low-grade ore deposits.
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    Microfossil characterisation for petroleum exploration using x-ray computed tomography: a new approach
    (Stellenbosch : Stellenbosch University, 2022-04) Tshibalanganda, Muofhe; Von der Heyden, Bjorn; Du Plessis, Anton; Tucker, Ryan T.; Stellenbosch University. Faculty of Science. Dept. of Earth Sciences.
    ENGLISH ABSTRACT: The current bulk processing and identification of microfossils from drill cores for petroleum exploration are limited by time-consuming traditional chemical and physical microfossil extraction and microscope inspection methods. Microfossils are removed from preserved rocks through mechanical disaggregation and conventional acid digestion techniques and then imaged using scanning electron microscopy, transmitted light microscopy, stereo binocular- or polarising microscopy depending on the microfossil group. In recent years, the application of micro-computed tomography (microCT) in micropaleontology has allowed non-destructive imaging of microfossils, but this is still perceived as challenging as there is a lack of methodology and technical details for high-resolution imaging of microfossils. In this study, the potential of microCT to characterise microfossils for petroleum exploration was evaluated. Application-specific challenges and advantages of imaging microfossils in drill cores were documented. This study successfully demonstrated that this method's viability increases with the use of drill cuttings and small fragments, showing different external and internal microfossil morphology characteristics imaged in 3D. Moreover, 3D imaging of extracted microfossils provided high taxonomic resolution. With the new insight, microCT and thermally induced colour were used to evaluate if specific changes in morphology can be linked to the thermal maturity of the source rock. The results indicated that the overall change in microfossil assemblage morphology might be useful in estimating a change in thermal maturity. MicroCT presents an exciting new tool for microfossil characterisation in petroleum exploration but requires automation to be economically viable.
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    Systematic experiments to quantitatively assess image quality for CT scans of a Karoo tetrapod fossil
    (Evolutionary Studies Institute, 2019) Tshibalanganda, Muofhe; Du Plessis, Anton; Le Roux, Stephan G.; Taylor, Wendy L.; Smith, Roger M. H.; Browning, Claire
    Over the past decade non-destructive, three-dimensional visualization and analysis of fossils using X-ray tomography has greatly advanced palaeontological studies worldwide. Micro-computed tomography (microCT) is now accepted as best practice in palaeontological studies to augment the anatomical description of newly discovered fossils. Despite advances in laboratory microCT hardware, software and skills of users, there is a lack of clear methodologies for scanning and analysing fossils. Here we report on a systematic and detailed study of the quantitative effects of the variation of different microCT scanning parameters on the image quality of an unprepared fossilized Karoo tetrapod skull and parts of the postcrania. Results indicate that voltage variations do not increase the contrast for the bone as one would expect, and the best image quality solution is found using high frame averaging and high X-ray flux (current). Although this study was limited to one specimen, the results may find a practical use for future studies involving similar fossils.
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    X-ray micro-tomographic data of live larvae of the beetle Cacosceles newmannii
    (GigaScience Press, 2021-04-21) Lehmann, Philipp; Javal, Marion; Du Plessis, Anton; Tshibalanganda, Muofhe; Terblanche, John S.
    Quantifying insect respiratory structures and their variation has remained challenging due to their microscopic size. Here we measure insect tracheal volume using X-ray micro-tomography (μCT) scanning (at 15 μm resolution) on living, sedated larvae of the cerambycid beetle Cacosceles newmannii across a range of body sizes. In this paper we provide the full volumetric data and 3D models for 12 scans, providing novel data on repeatability of imaging analyses and structural tracheal trait differences provided by different image segmentation methods. The volume data is provided here with segmented tracheal regions as 3D models.