Scielo RSS <![CDATA[South African Journal of Science]]> http://www.scielo.org.za/rss.php?pid=0038-235320160006&lang=pt vol. 112 num. 11-12 lang. pt <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Resolving fractured debates about fracking? The shale gas industry in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600001&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Associate Editor awarded Science-for-Society Gold Medal</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600002&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>ASSAf and young scientists: Transforming the future of science in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600003&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Sex and gender transformation in Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600004&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Understanding the polarisation of environmental and social activism in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600005&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>A note on aspects of risk and return for South African bond investors</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600006&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Science to policy - Reflections on the South African reality</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600007&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Towards the study of South African literature as an integrated corpus</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600008&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Military psychologists as scientists and practitioners</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600009&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>From biological control to controlling biology</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600010&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>The phenomenon of skin lightening: Is it right to be light?</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600011&lng=pt&nrm=iso&tlng=pt Chemicals capable of lightening the skin - variously known as skin-bleaching, skin-lightening, depigmenting, skin-evening and skin-brightening agents - are among the most commonly used skin preparations in the world. Globally, Africa reportedly exhibits a high prevalence of skin lightener use. In this review, we provide both clinical and social perspectives on skin lightener use in Africa, with particular emphasis on South Africa. We narratively explore the timeline associated with skin lightener use in South Africa and attempt to interweave the social rhetoric of this specific paradigm. Despite the risks associated with exposing the skin to known constituents of these formulations, such as hydroquinone and mercury, chronic use continues. In spite of legislation banning hydroquinone and mercury in cosmetics in South Africa, these ingredients are present in widely available products. We recommend better implementation of policies and greater ethical responsibility of multinational cosmetic companies in addition to the initiation of a system of random product testing and penalties that could improve industry compliance. SIGNIFICANCE: • There is a high prevalence of skin lightener use in Africa. • Despite legislation banning harmful compounds, these compounds are still used in skin lightening formulations. • There is an urgent need to implement policies and recommendations for preventing the influx and illicit sale and use of untested skin lighteners. <![CDATA[<b>Palaeomagnetic results and new dates of sedimentary deposits from Klasies River Cave 1, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600012&lng=pt&nrm=iso&tlng=pt Palaeomagnetic data from Klasies River main site Cave 1 (Eastern Cape Province, South Africa) are reported. Natural remanent magnetisation directions obtained from 77 oriented samples were determined by progressive alternating field demagnetisation methodology. Three palaeomagnetic samplings from the Witness Baulk from the Middle Stone Age (MSA) Late Pleistocene White Sand member and the Holocene Later Stone Age (LSA) middens in Cave 1 were dated and analysed to obtain the palaeomagnetic directions recorded in the sediments. Here we provide new optically stimulated luminescence (OSL) dates for the White Sand Member, and new accelerator mass spectrometry (AMS) radiocarbon dates for the LSA midden of areas not previously dated. The palaeomagnetic analysis took into account rock magnetism and directional analysis. The former reveals that the main magnetic carrier was magnetite; the latter shows that characteristic remanent magnetisation of normal and anomalous directions were observed in the lower portion of the White Sand Member and LSA midden. Normal directions correspond to the palaeosecular variation record for South Africa during the Late Pleistocene. On the other hand, the anomalous directions recorded in the LSA midden might represent the likely Sterno-Etrussia geomagnetic field excursion which occurred during the Late Holocene and is observed in other places on the planet. Finally, the directional data obtained are a potential tool for discussing the age of deposits corresponding to those periods. SIGNIFICANCE: • New dates confirm and extend previous age determinations for the LSA and White Sand Member from Klasies River <![CDATA[<b>Characterisation of smectite-rich clay soil: Implication for groundwater defluoridation</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600013&lng=pt&nrm=iso&tlng=pt Groundwater is a widely used and affordable source of drinking water in most of the rural areas of South Africa. Several studies have indicated that groundwater in some boreholes in South Africa has a fluoride concentration above the level recommended by the World Health Organization (1.5 mg/L). Fluoride concentrations above the permissible limit (>1.5 mg/L) lead to dental fluorosis, with even higher concentrations leading to skeletal fluorosis. In the present work, we evaluate the application of smectite-rich clay soil from Mukondeni (Limpopo Province, South Africa) in defluoridation of groundwater. The clay soil was characterised by mineralogy using X-ray diffraction, by elemental composition using X-ray fluorescence and by morphology using scanning electron microscopy. Surface area and pore volume was determined by the Brunauer-Emmett-Teller surface analysis method. Cation exchange capacity and pHpzc of the soil were also evaluated using standard laboratory methods. Batch experiments were conducted to evaluate and optimise various operational parameters such as contact time, adsorbent dose, pH and initial adsorbate concentration. It was observed that 0.8 g/100 mL of smectite-rich clay soil removed up to 92% of fluoride from the initial concentration of 3 mg/L at a pH of 2 with a contact time of 30 min. The experimental data fitted well to a Langmuir adsorption isotherm and followed pseudo second order reaction kinetics. Smectite-rich clay soil showed 52% fluoride removal from field groundwater with an initial fluoride concentration of 5.4 mg/L at an initial pH of 2 and 44% removal at a natural pH of 7.8. Therefore smectite-rich clay soil from Mukondeni has potential for application in defluoridation of groundwater. Chemical modification is recommended to improve the defluoridation capacity. SIGNIFICANCE: • Physicochemical and mineralogical characterisation of smectite-rich clay soil • Defluoridation of groundwater using smectite-rich clay soil • Adsorption modelling using adsorption isotherms and kinetic models <![CDATA[<b>Stirred cell ultrafiltration of lignin from black liquor generated from South African kraft mills</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600014&lng=pt&nrm=iso&tlng=pt Ultrafiltration of lignin from black liquor was carried out in a stirred batch cell using polyethersulfone membranes. Parameters such as operating pressure, feed concentration, stirring rate and membrane cut-off size were varied and their effects on lignin retention and permeate flux were investigated. The operating pressure, feed concentration and stirring rate were varied in the ranges 150-350 kPa, 3-9% and 200-400 rpm, respectively. The membranes used had cut-off sizes of 5 kDa, 10 kDa and 20 kDa. A one-factor-at-a-time experimental design approach was applied in this study. Retention of lignin increased with increases in operating pressure, feed concentration and stirring rate, but decreased with an increase in molecular cut-off size of the membrane. Permeate flux on the other hand increased with increases in pressure, stirring rate and molecular cut-off size of the membrane but decreased with an increase in feed concentration. The extraction of lignin from black liquor was successfully carried out and extraction efficiencies as high as 86% could be achieved depending on the experimental conditions. The study was concluded with the recommendation of conducting additional experiments using a pilot plant in a continuous mode. SIGNIFICANCE: • The extraction of lignin from black liquor was successfully carried out and extraction efficiencies as high as 86% were obtained. The results can be used to extend the ultrafiltration of black liquor to an industrial scale. <![CDATA[<b>Impact of mother tongue on construction of notes and first-year academic performance</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600015&lng=pt&nrm=iso&tlng=pt The purpose of this study was to identify whether there are any differences in the quality of the notes constructed in English between students for whom English is a first language and those for whom it is a second language. Subsequently we assessed whether this difference, if any, affected their grades. Unsurprisingly, the first-language students produced better structured and more detailed notes; they also performed better academically than their second-language peers. However, when students were provided with training that focused on using writing as a means to promote critical thinking, there was an improvement in the personalisation of their notes. The improvement in grades was significant for second-language students. Thus the university has a pivotal role to play in preparing students for academic success by providing them with supportive measures to aid their transition into first year. SIGNIFICANCE: • The work illustrates that writing can be used as a tool for students to improve their learning and their academic performance. • Second-language students' grades improve when writing interventions are provided early in the year. • Students need to take on the responsibility for their learning; lecturers also have a responsibility in scaffolding learning. <![CDATA[<b>Student-perceived criteria for assessing university relevance in community development</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600016&lng=pt&nrm=iso&tlng=pt In sub-Saharan Africa, universities are increasingly being called upon to contribute more towards combating poverty and promoting development in rural areas. Yet, it is still argued that universities are ivory towers, and as a result, their contribution to finding sustainable solutions to issues hampering the realisation of improved quality of life of people in rural areas remains unsatisfactory. This perception emanates from the universities' apparent failure to articulate and demonstrate how they can achieve the desired goal stated above. Moreover, there are no universally embraced criteria for assessing the relevance of a rural area based university to the community it serves. This study was therefore carried out to determine the perceptions of University of Venda undergraduate students on what they believed were appropriate criteria for assessing the relevance of a rural area based university in community development in South Africa. Reflection circles, anchored on participatory research techniques, were used to engage the students. The results of the engagement were organised into sub-themes. The most prominent perceptions were: 'A university has active long-term community-based development initiatives'; 'A university is continuously addressing the real needs of the communities in question'; 'University initiatives are creating jobs for its graduates and community members'; and 'Continuous community requests for university assistance in solving the challenges militating against development'. The wide range of perceptions of students observed in this study is a useful input into initiatives seeking to develop an objective tool for assessing the relevance of a rural area based university in community development. SIGNIFICANCE: • A set of criteria that students believe should be used to assess the relevance of universities in community development were generated. • The criteria can be used to develop an index that might serve as a tool for ranking university relevance to their constituencies. • The criteria can also be used to sharpen the business of community engagement directorates in ruralbased universities. <![CDATA[<b>A bibliometric assessment of energy research in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600017&lng=pt&nrm=iso&tlng=pt The results of an effort to identify the performance of energy and fuels research in South Africa during the most recent period (2003-2013) are reported. Bibliometric approaches have been employed in order to assess the field of energy research. Energy research was identified to be improving over time, albeit from a small basis. The field appears to equally emphasise fossil and renewable energy research. Similarly, universities were identified to be producing a subcritical number of energy articles in comparison with international organisations. The relatively small activity in the energy field appears to affect the international collaboration of the field, which is well below the national average. International comparisons in terms of articles per GWH of electricity produced and articles per million population show that South Africa should increase substantially its effort in the field in order to be comparable with other countries. SIGNIFICANCE: • This article makes a unique contribution in scientometrics to the field of energy research in South Africa which, given its multidisciplinary nature, is a generally neglected field of study in South Africa. <![CDATA[<b>Formulating tasks to develop HOTS for first-year calculus based on Brookhart abilities</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600018&lng=pt&nrm=iso&tlng=pt We describe an approach to develop higher-order thinking skills (HOTS) among first-year calculus students. The ideas formulated by Brookhart to develop HOTS were used to identify from the literature three core abilities that should be targeted. Then eight expected learning outcomes for the development of HOTS were documented, in the context of the study of first-year university calculus. Those expected outcomes were used to formulate sample tasks that were designed to target the development of the eight abilities. A pilot study was done to determine whether the tasks had the high mathematical demand envisaged. It was found that about 37% of the participants did not give any response to the tasks. Further it was found that about 31% of the participants were able to critically evaluate a given possible solution to a problem and make a value judgement. It is recommended that to promote HOTS among students, the formulation of tasks should focus on developing the following abilities: interpreting a general definition or statement in the context of a given model; translating a worded or graphically represented situation to relevant mathematical formalisms; identifying possible applications of mathematics in their surroundings; identifying linkages between groups of concepts and interpreting these linkages in the context of a model; working systematically through cases in an exhaustive way; critically evaluating one's and others' presented solutions to a problem; interpreting and extending solutions of problems; and using with reasonable skill available tools for mathematical exploration. SIGNIFICANCE: • A large proportion of the student intake at university level is unable to answer mathematics questions that focus on HOTS. There is therefore a need to deliberately focus on and promote HOTS amongst the average students in the context of calculus. <![CDATA[<b>A spatio-temporal analysis of fires in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600019&lng=pt&nrm=iso&tlng=pt The prevalence and history of fires in Africa has led to the continent being named 'the fire continent'. Fires are common on the continent and lead to a high number of annual fire disasters which result in many human fatalities and considerable financial loss. Increased population growth and concentrated settlement planning increase the probability of fire disasters and the associated loss of human life and financial loss when disasters occur. In order to better understand the spatial and temporal variations and characteristics of fires in South Africa, an 11-year data set of MODIS-derived Active Fire Hotspots was analysed using an open source geographic information system. The study included the mapping of national fire frequency over the 11-year period. Results indicate that the highest fire frequency occurred in the northeastern regions of South Africa, in particular the mountainous regions of KwaZulu-Natal and Mpumalanga, and in the Western Cape. Increasing trends in provincial fire frequency were observed in eight of the nine provinces of South Africa, with Mpumalanga the only province for which a decrease in annual fire frequency was observed. Temporally, fires were observed in all months for all provinces, although distinct fire seasons were observed and were largely driven by rainfall seasons. The southwestern regions of South Africa (winter-rainfall regions) experienced higher fire frequencies during the summer months and the rest of the country (summer-rainfall regions) during the winter months. Certain regions - those which experienced bimodal rainfall seasons - did not display distinct fire seasons because of the complex wet and dry seasons. Investigation into the likely effects of climate change on South African fire frequency revealed that increased air temperatures and events such as La Niña have a marked effect on fire activity. SIGNIFICANCE: • Fires have played a significant role in the morphology of the African continent. • Fires provide a number of environmental services. • Fires were observed in all months in all provinces in South Africa, although distinct fire seasons were observed and were largely driven by rainfall seasons. • Global climate change will result in an increase in the frequency of fires. <![CDATA[<b>Deriving cues from human cognition for the modelling of shack boundaries in aerial imagery</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600020&lng=pt&nrm=iso&tlng=pt Organic studies inspire cues for modelling logic in image processing and become a basis for the development of novel remote-sensing algorithms. Examples of applications of such paradigms include the growing application of techniques such as object-oriented analysis and neural networks in image analysis for which the logic was drawn from studying various components of organic systems in the human body. Here we document a key investigation based on a set of cognitive tests conducted using aerial imagery captured over Cape Town (South Africa). These tests were conducted to later draw parallels with a feature extraction algorithm for shack settlements. We found that the visual variables of 'pattern' and 'shape' display the most significant cognitive guide for shack boundary extraction. Although the focus here was on digital imagery, learning points can be selected for application in other scientific fields as well. SIGNIFICANCE: • Provides an interest point for several image-processing and computer vision sciences. • Contributes to geospatial studies and helps improve mapping and imaging initiatives. • Directed towards solving the challenges that urban governors face in slum management. <![CDATA[<b>A morphometric analysis of hominin teeth attributed to <i>Australopithecus, Paranthropus </i>and <i>Homo</i></b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600021&lng=pt&nrm=iso&tlng=pt Teeth are the most common element in the fossil record and play a critical role in taxonomic assessments. Variability in extant hominoid species is commonly used as a basis to gauge expected ranges of variability in fossil hominin species. In this study, variability in lower first molars is visualised in morphospace for four extant hominoid species and seven fossil hominin species. A size-versus-shape-based principle component analysis plot was used to recognise spatial patterns applicable to sexual dimorphism in extant species for comparison with fossil hominin species. In three African great ape species, variability occurs predominantly according to size (rather than shape), with the gorilla sample further separating into a male and a female group according to size. A different pattern is apparent for the modern human sample, in which shape variability is more evident. There is overlap between male and female modern humans and some evidence of grouping by linguistic/tribal populations. When fossil hominin species are analysed using equivalent axes of variance, the specimens group around species holotypes in quite similar patterns to those of the extant African great apes, but six individual fossil molars fall well outside of polygons circumscribing holotype clusters; at least three of these specimens are of interest for discussion in the context of sexual dimorphism, species variability and current species classifications. An implication of this study is that, especially in the case of modern humans, great caution needs to be exercised in using extant species as analogues for assessing variability considered to be a result of sexual dimorphism in fossil hominin species. <![CDATA[<b>Cytotoxic activity of marine sponge extracts from the sub-Antarctic Islands and the Southern Ocean</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000600022&lng=pt&nrm=iso&tlng=pt Over the past 50 years, marine invertebrates, especially sponges, have proven to be a valuable source of new and/or bioactive natural products that have the potential to be further developed as lead compounds for pharmaceutical applications. Although marine benthic invertebrate communities occurring off the coast of South Africa have been explored for their biomedicinal potential, the natural product investigation of marine sponges from the sub-Antarctic Islands in the Southern Ocean for the presence of bioactive secondary metabolites has been relatively unexplored thus far. We report here the results for the biological screening of both aqueous and organic extracts prepared from nine specimens of eight species of marine sponges, collected from around Marion Island and the Prince Edward Islands in the Southern Ocean, for their cytotoxic activity against three cancer cell lines. The results obtained through this multidisciplinary collaborative research effort by exclusively South African institutions has provided an exciting opportunity to discover cytotoxic compounds from sub-Antarctic sponges, whilst contributing to our understanding of the biodiversity and geographic distributions of these cold-water invertebrates. Therefore, we acknowledge here the various contributions of the diverse scientific disciplines that played a pivotal role in providing the necessary platform for the future natural products chemistry investigation of these marine sponges from the sub-Antarctic Islands and the Southern Ocean. SIGNIFICANCE: • This study will contribute to understanding the biodiversity and geographic distributions of sponges in the Southern Ocean. • This multidisciplinary project has enabled the investigation of marine sponges for the presence of cytotoxic compounds. • Further investigation will lead to the isolation and identification of cytotoxic compounds present in the active sponge extracts.