South African Journal of Science最新文献

{"title":"South African grasslands and ploughing: Outlook for agricultural expansion in Africa","authors":"Elaine Slooten, Eulalia Jordaan, Joseph D.M. White, Sally Archibald, Frances Siebert","doi":"10.17159/sajs.2023/15540","DOIUrl":"https://doi.org/10.17159/sajs.2023/15540","url":null,"abstract":"","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135343337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a chitosan-multi-walled carbon nanotubes composite for application in solid-phase adsorption toxin tracking of microcystins","authors":"Glynn K. Pindihama, Mugera W. Gitari, Rabelani Mudzielwana, Ntakadzeni E. Madala","doi":"10.17159/sajs.2023/14786","DOIUrl":"https://doi.org/10.17159/sajs.2023/14786","url":null,"abstract":"Contamination of water and food with cyanotoxins poses human health risks, and hence the need for sensitive early warning tools to monitor these in water. A composite of glutaraldehyde-crosslinked chitosan and multi-walled carbon nanotubes (ChMWCNTs) was synthesised and tested for potential use as a solid-phase adsorption toxin tracking (SPATT) adsorbent for monitoring microcystins (MCs) in fresh water. The composite was characterised by Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller theory and scanning electron microscopy. Batch adsorption experiments to assess the effect of contact time, adsorbent dosage and initial microcystin-LR (MC-LR) concentration were conducted. The composite was found to be efficient in adsorbing MC-LR, showing 97% removal and a maximum adsorption capacity of 4.639 μg/g under optimised conditions of 5 μg/L of MC-LR, adsorbent dose of 0.03 g/5 mL and 30 min contact time. The adsorption kinetics were better explained by a pseudo-second-order model, inferring chemisorption adsorption. The isotherm data better fitted the Langmuir isotherm model, thus inferring monolayer surface adsorption. For desorption, 100% methanol was the most effective, with an efficiency of 84.71%. The composite effectively adsorbed and desorbed three congeners of MCs (–LR, –RR and –YR) when tested in raw dam water, regardless of its lower maximum adsorption capacity compared to those of other adsorbents used for similar purposes.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135343338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"GYPWORLD Africa: Setting an agenda for gypsum ecosystem research in southern Africa","authors":"Stefan J. Siebert, Sara Palacio, Arantzazu L. Luzuriaga, Gillian Maggs-Kölling, Eugene Marais, Silvia Matesanz, María Prieto, Yolanda Pueyo, Nishanta Rajakaruna, Ana M. Sánchez, Sarina Claassens","doi":"10.17159/sajs.2023/15308","DOIUrl":"https://doi.org/10.17159/sajs.2023/15308","url":null,"abstract":"This paper introduces gypsum ecosystem research to southern Africa. It is the result of current joint efforts to compare African gypsum ecosystems with those in other parts of the world. We highlight the expansion of an international network through joint projects and training of young scientists. We propose a research agenda to sensitise the ecological community in Africa to the significance of life on gypsum and to demystify the existence of gypsum soil and associated ecosystems in southern Africa. Gypsum ecosystem research is rapidly moving up the international research agenda to better understand the dynamics and resilience of the life systems associated with atypical soils that are frequent in semi-arid to arid ecosystems. The southern African soil classification system does not sufficiently recognise the presence of gypsum as a differentiating criterion, hence not much is known about the region’s gypsum soil, and gypsum ecology has subsequently been largely neglected. This neglect is unfortunate, as the livelihoods of people are dependent on these gypsum ecosystems and these areas are worthy of protection due to the rare biotas that are adapted to survive in these harsh environments.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135343344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physical anthropology through the eyes of the scientists","authors":"Himla Soodyall","doi":"10.17159/sajs.2023/16804","DOIUrl":"https://doi.org/10.17159/sajs.2023/16804","url":null,"abstract":"Book Review In Bones and Bodies, Alan Morris brings to life the historic narrative of how “the skeletons I study were once the frames of living people” (p. 2) and how “biological information can have no value without understanding the social and cultural context of the people” (p. 2). Morris ploughed through collections of correspondence between early researchers in the field and volumes of literature, and conducted interviews with seminal figures in the fields of physical anthropology, archaeology and palaeontology, among others, to eloquently narrate the contribution of scholars who shaped the physical anthropology landscape in South Africa.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135344739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accessory gene regulators and virulence genes associated with the pathogenicity of Staphylococcus aureus from clinical and community settings in Lagos, Nigeria","authors":"Nkechi V. Enwuru, Solayide A. Adesida, Christian A. Enwuru, Udoma E. Mendie","doi":"10.17159/sajs.2023/10901","DOIUrl":"https://doi.org/10.17159/sajs.2023/10901","url":null,"abstract":"Staphylococcus aureus is a prominent pathogen that causes serious community and hospital-acquired infections globally. Its pathogenicity is attributed to a variety of secreted and cell surface associated proteins that are modulated by the quorum-sensing accessory gene regulator (agr) system. In this study, we investigated the presence of toxin genes and agr involved with S. aureus from clinical samples and apparently healthy individuals. Unequivocal identification of the isolates was obtained with the Vitek 2 system. We screened 70 clinical (CL) and 22 community (C) S. aureus strains for the methicillin resistance (mecA) gene, agr and superantigens (SAg) (enterotoxins and toxic shock syndrome toxin-1) using PCR techniques. A total of 12 clinical isolates were classified as methicillin-resistant S. aureus (MRSA); 89 isolates belonged to one of the four agr groups (agr1-4), and 3 isolates were non-typeable. Of the agr groups, agr1 was the most prominent and mostly consisted of isolates from pus/wounds. The methicillin-susceptible S. aureus (MSSA) isolates were distributed within the four agr groups while MRSA strains were restricted to agr1 and agr3. The most common enterotoxin gene, sei, was likewise more prevalent in MSSA strains than in MRSA strains, where sea predominated. The co-existence of two or more enterotoxins was confirmed in 40% of the isolates. sea occurred through all the agr groups except agr3 and sei was not found in agr1 and agr4. The toxic shock toxin (tst) gene was detected in six MSSA. These findings suggest that MSSA may cause more lethal infections than MRSA because of the increased frequency of toxic genotypes seen in MSSA strains.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":"229 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135344760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Building a carbon dioxide removal science–policy partnership for southern Africa","authors":"Pedro M.S. Monteiro, Guy F. Midgley","doi":"10.17159/sajs.2023/16320","DOIUrl":"https://doi.org/10.17159/sajs.2023/16320","url":null,"abstract":"which will impact society through carbon pricing, management of climate risk, and the costs of adaptation and mitigation. Finally, there are risks related to the as-yet uncertain feasibility and scalability of the technological interventions, such as direct air capture of CO 2 , biomass energy with carbon capture (BECCS)","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135385232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Charles Kimberlin (Bob) Brain (1931–2023): Naturalist, scientific leader, and family man","authors":"Bruce Rubidge","doi":"10.17159/sajs.2023/16660","DOIUrl":"https://doi.org/10.17159/sajs.2023/16660","url":null,"abstract":"","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135343342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An assessment of the economic impact of South Africa’s public universities","authors":"Ahmed C. Bawa, Anastassios Pouris","doi":"10.17159/sajs.2023/14851","DOIUrl":"https://doi.org/10.17159/sajs.2023/14851","url":null,"abstract":"With the understanding that universities play multiple social purposes, we aimed to provide an estimation of the economic impact of the public universities in South Africa. Using models described in the literature, we estimated economic benefits from four university activities – university exports, research at universities, the production of graduates and universities as business entities. Comparative analysis shows that, as an economic sector, Higher Education contributes more to South Africa’s gross value added than other economic sectors such as Wood and Wood Products, Textiles, Clothing and Leather Goods, or Paper and Paper Products. It is comparable to sectors such as Gold Mining, and Beverages and Tobacco. Taking into account a number of assumptions, which are explained in the text, for 2018 the total economic impact was estimated at about ZAR513 billion. Governmental expenditure on higher education in that year was ZAR66 billion. These figures produce a cost–benefit ratio for the sector of 1 : 7.7, considering only these four university activities.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135344809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the adoption of improved seeds as a coping strategy to climate variability under smallholder farming conditions in South Africa","authors":"Lindumusa Myeni, Mokhele E. Moeletsi","doi":"10.17159/sajs.2023/15001","DOIUrl":"https://doi.org/10.17159/sajs.2023/15001","url":null,"abstract":"This study was undertaken to examine the adoption rate, constraints and factors determining the uptake of improved seed varieties in smallholder farming conditions of South Africa, using a maize crop. Primary data were collected from 279 smallholder farmers in the Maluti-a-Phofung municipality of the Free State Province using a household questionnaire and were validated through focus group discussions with key local informants. Descriptive statistics, frequency analysis and a binary logistic model were used for data analysis. Results show that the majority of the farmers (>69%) were growing uncertified local seed varieties saved from their previous harvest or acquired from neighbouring farmers. The lack of awareness and knowledge of, inadequate information, unaffordability and unavailability of improved seeds, low income and landlessness were major constraints limiting the adoption rate. Age and income were the main variables that had a positive and significant effect on the adoption of improved seed varieties, whilst ownership of livestock had a significant and negative influence on their adoption. As a result, the promotion of improved seed varieties needs to be supported by conducive and effectual institutional policies that will improve the provision of extension services, capacity-building initiatives, subsidy programmes, financial resources and good agricultural lands, and reduce the transaction costs of improved seed varieties. The recommendations from this study can be used by the government and other developmental organisations to enhance the wider uptake and use of improved seed varieties in smallholder farming conditions not only in the study area but also in other regions with similar challenges.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135421120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Association of accelerometry-based and self-reported physical activity with cardiovascular risk in South African children","authors":"Patricia Arnaiz, Felix Guntlisbergen, Denis Infanger, Markus Gerber, Larissa Adams, Danielle Dolley, Nandi Joubert, Madeleine Nienaber, Siphesihle Nqweniso, Rosa du Randt, Peter Steinmann, Jürg Utzinger, Cheryl Walter, Uwe Pühse, Ivan Müller","doi":"10.17159/sajs.2023/15494","DOIUrl":"https://doi.org/10.17159/sajs.2023/15494","url":null,"abstract":"The burden of non-communicable diseases is increasing, with risk factors emerging early in life. Physical activity reduces cardiovascular risk, but limited evidence exists for children from lower-income countries and mostly relies on self-reported methods that might be inaccurate and biased. We aimed to compare self-reported and accelerometer-measured physical activity in relation to cardiovascular risk markers in children from underserved communities in South Africa. We analysed cross-sectional data from 594 children aged 8 to 13. Physical activity was measured via accelerometry and the Physical Activity Questionnaire for Older Children (PAQ-C). Correlation analyses and linear regression models examined the relationship between accelerometer-measured and self-reported physical activity and their association with cardiovascular risk markers (body mass index, blood pressure, blood lipid profile and glycated haemoglobin). Results show a positive but weak correlation between PAQ-C scores and accelerometer-measured moderate-to-vigorous physical activity (MVPA). MVPA was inversely associated with body mass index, whilst sedentary behaviour correlated positively with lipid levels. PAQ-C scores were inversely associated with systolic blood pressure. The comparison of self-reported and accelerometer-measured physical activity in children from Gqeberha, South Africa, revealed inconsistencies in their correlation and association with cardiovascular risk markers. Accelerometry provided a more accurate cardiovascular risk estimation than PAQ-C, although associations were weak. Further, longitudinal studies should investigate the predictive power of both methodologies. These findings inform researchers and public health practitioners in the choice of method for physical activity appraisal beyond practical considerations, especially when combined with cardiovascular risk and in lower-income settings.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135344812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}