Research Articles (School for Science and Technology)
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- ItemEffect of the elemental content of shells of the bivalve mollusks (Mytilus galloprovincialis) from Saldanha Bay (South Africa) on their crystallographic texture(MDPI, 2021) Nekhoroshkov, Pavel; Zinicovscaia, Inga; Nikolayev, Dmitry; Lychagina, Tatiana; Pakhnevich, Alexey; Yushin, Nikita; Bezuidenhout, JacquesA both wild and farmed mussels in natural conditions, anthropogenic inputs are usually reflected in the increase of the content of specific elements. To determine the possible effect of the elemental patterns of farmed and wild mussels (Mytilus galloprovincialis) collected in the Saldanha Bay area (South Africa) on the crystallographic texture of the shells, the content of 20 elements in shells and 24 in the soft tissue of mussels was determined by neutron activation analysis. The crystallographic texture of mussel shells was analyzed using time-of-flight neutron diffraction. The wild mussels from open ocean site live in stressful natural conditions and contain higher amounts of the majority of determined elements in comparison with mussels farmed in closed water areas with anthropogenic loadings. The changes between the maximums of the same pole figures of the three samples are in the range of variability identified for the genus Mytilus. The content of Cl, Sr, and I was the highest in mussels from the open ocean site, which is reflected by the lowest mass/length ratio. The determined crystallographic textures of mussels are relatively stable as shown in the analyzed pole figures despite the concentrations of Na, Mg, Cl, Br, Sr, and I in shells, which significantly differ for wild and farmed mussels. The stability of the crystallographic texture that we observed suggests that it can be used as a reference model, where if a very different texture is determined, increased attention to the ecological situation should be paid.
- ItemEstimation of radon potential through measurement of uranium concentrations in granite geology(Academy of Science of South Africa, 2019) Bezuidenhout, JacquesThe geology of an area can be used as a predictor for radon potential. Granite rock typically contains a high concentration of uranium and subsequent elevated emanation of radon gas. The geology of the western part of the Western Cape Province in South Africa is dominated by granite bedrock but very few studies on radon have been conducted in this area. Uranium concentrations were consequently measured on a large granite hill in the Saldanha Bay area of the Western Cape and a relationship between indoor radon and uranium concentrations was used to model radon potential on the outcrop. Results from granite rich environments in India were modelled in order to extract a relationship between indoor radon concentrations, radon exhalation rates and uranium concentrations. Radon exhalation rates greater than 0.35 Bq/m2h were predicted and estimated indoor radon concentrations in excess of 400 Bq/m3 were also predicted for the hill. The modelled results were compared with indoor radon measurements taken in the town of Paarl in the Western Cape, which sits on the same granite bedrock formation. The predicted radon potential correlated well with the physical measurements.
- ItemInfluence of rotation on transversely isotropic piezoelectric rod coated with a thin film(Polish Academy of Sciences, 2018) Selvamani, Rajendran; Makinde, Oluwole DanielIn this paper, the influence of rotation on axisymmetric waves of a piezoelectric rod coated with a thin film is studied using constitutive form linear theory elasticity and piezo-electric equations. Potential functions are introduced to uncouple the equations of motion in radial and axial directions. The surface area of the rod is coated by a perfectly conducting material. The frequency equations are obtained for longitudinal and flexural modes of vibration and are studied numerically for PZT-4 ceramics. The computed non-dimensional frequency, phase velocity, relative frequency shift, electromechanical coupling and electric displacement are presented in the form of dispersion curves. This type of study is important in the construction of rotating sensors and gyroscope.
- ItemThe mapping and investigation of radionuclide pollution in the processing plant of a spent phosphate mine by using GIS techniques(CONSAS, 2018) Bezuidenhout, JacquesThe mining and refinement of phosphate is characterised by high levels of uranium. An in situ gamma ray survey was done at the processing plant of a spent phosphate mine near Vredenburg on the west coast of South Africa in order to assess radionuclide concentrations. The concentrations of potassium, thorium and radioactive progeny of uranium were measured and plotted with the help of QGIS software. The results demonstrated high concentrations in specific areas of the plant. The highest concentrations were found to be 898 Bq/kg for potassium, 162 Bq/kg for 232Th and 639 Bq/kg for 226Ra. It was demonstrated that the refinement process technologically enhanced the naturally occurring radioactive nuclides and contaminated sections of the processing plant. The causes of the contamination were also investigated. The effective dose for the various parts of the processing plant was also estimated and the highest level was found to be 0.45 mSv/y. The article finally draws conclusions as to the environmental impact of the radiation and possible future preventative measures that could be followed in order to minimize pollution.
- ItemNew interventions and sustainable solutions : reappraising illegal artisanal mining in South Africa(University of Cape Town, Centre of Criminology, 2018) Mkhize, Mbekezeli ComfortDespite being recognised as a significant contributor in the South African economy, the mining industry is riddled with illegal mining activities. Though it remains difficult to precisely measure the extent of the activities in financial terms, it is estimated that more than R72 Billion have been lost. Lack of research on illegal mining partly compounds the problem. In view of this knowledge-gap, this article argues that whilst there is a multiplicity of stakeholders who deal directly with unlawful activities, poor integration of capacities at different levels remain discernible. The article assesses available literature and employs two theoretical perspectives as lenses through which to view the underlying reasons and the measures that can be put in place to quell illegal mining. The article concludes that an integrated model needs to be put in place in order to quell illegal mining in South Africa. The article recommends that the resources need to be pulled together and collaborative efforts need to be enhanced at all levels.