Pub Date : 2024-03-27DOI: 10.17159/sajs.2024/16026
Simoné Karels, C. Felix, S. Pasupathi
IrO2 is a current state-of-the-art catalyst for polymer electrolyte membrane water electrolyser (PEMWE) applications due to its high stability during the oxygen evolution reaction (OER). However, its activity needs to be significantly improved to justify the use of such a high-cost material. In this study, the activity of the IrO2 catalyst was improved by optimising and comparing two synthesis methods: the modified Adams fusion method (MAFM) and the molten salt method (MSM). Optimum OER performances of the IrO2 catalysts synthesised with the two synthesis methods were obtained at different temperatures. For the MAFM, a synthesis temperature of 350 °C produced the IrO2 catalyst with an overpotential of 279 mV and the highest OER stability of ~ 82 h at 10 mAcm−2. However, for the MSM, the lowest overpotential of 271 mV was observed for IrO2 synthesised at 350 °C, while the highest stability of ~ 75 h was obtained for the IrO2 synthesised at 500 °C.
由于在氧进化反应(OER)过程中具有高稳定性,IrO2 是目前聚合物电解质膜水电解槽(PEMWE)应用中最先进的催化剂。然而,为了证明使用这种高成本材料的合理性,其活性需要大幅提高。在本研究中,通过优化和比较两种合成方法:改良亚当斯熔融法(MAFM)和熔盐法(MSM),提高了二氧化铱催化剂的活性。在不同温度下,用这两种合成方法合成的二氧化铱催化剂都能获得最佳的 OER 性能。在 MAFM 法中,合成温度为 350 ℃ 时生成的 IrO2 催化剂过电位为 279 mV,在 10 mAcm-2 条件下的 OER 稳定性最高,达到约 82 h。然而,对于 MSM,在 350 °C 下合成的 IrO2 的过电位最低,为 271 mV,而在 500 °C 下合成的 IrO2 的稳定性最高,约为 75 h。
{"title":"Development of unsupported IrO2 nano-catalysts for polymer electrolyte membrane water electrolyser applications","authors":"Simoné Karels, C. Felix, S. Pasupathi","doi":"10.17159/sajs.2024/16026","DOIUrl":"https://doi.org/10.17159/sajs.2024/16026","url":null,"abstract":"IrO2 is a current state-of-the-art catalyst for polymer electrolyte membrane water electrolyser (PEMWE) applications due to its high stability during the oxygen evolution reaction (OER). However, its activity needs to be significantly improved to justify the use of such a high-cost material. In this study, the activity of the IrO2 catalyst was improved by optimising and comparing two synthesis methods: the modified Adams fusion method (MAFM) and the molten salt method (MSM). Optimum OER performances of the IrO2 catalysts synthesised with the two synthesis methods were obtained at different temperatures. For the MAFM, a synthesis temperature of 350 °C produced the IrO2 catalyst with an overpotential of 279 mV and the highest OER stability of ~ 82 h at 10 mAcm−2. However, for the MSM, the lowest overpotential of 271 mV was observed for IrO2 synthesised at 350 °C, while the highest stability of ~ 75 h was obtained for the IrO2 synthesised at 500 °C.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140376887","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}
Pub Date : 2024-03-27DOI: 10.17159/sajs.2024/15969
K. Omeje, B. O. Ezema, S. Eze
Pesticide residues and heavy metal content of cassava, yam, cocoyam, potato, water yam and carrot were evaluated by gas chromatography–mass spectrometry and atomic absorption spectroscopy. The detected pesticide residues in the samples were 2,4-dichlorophenoxyacetic acid, glyphosate, hexachlorobenzene (HCB), dichlorobiphenyl, aldrin, endosulfan, profenofos, g-chlordane, carbofuran, biphenyl, heptachlor, lindane and t-Nonachlor. The concentration of HCB ranged between 0.0799 ± 0.06 mg/kg and 0.1596 ± 0.00 mg/kg, which was greater than the permitted maximum limit of 0.5 mg/kg established by the US Environmental Protection Agency. The concentration of aldrin and profenofos detected was lower than the predetermined maximum allowed limits. Endosulfan concentrations in cocoyam (0.2500 mg/kg) and potato (0.3265 mg/kg) were higher than the limits allowed by the Canadian Department of Industrial Research. The heavy metals detected in these samples include cobalt, nickel, lead, manganese, chromium, arsenic and mercury in at least one of the samples evaluated. There was not much difference between the concentration of cobalt in yam (0.036 mg/kg) and the maximum allowed concentration (0.043 mg/kg). Lead was detected in potatoes and carrots but was below detectable concentration in cassava, yam, cocoyam and water yam. Similarly, cocoyam was found to have a significant mercury content (0.658 mg/kg), but mercury content was below detectable concentrations in cassava, yam and water yam.
{"title":"Evaluation of pesticide residues and heavy metals in common food tubers from Nigeria","authors":"K. Omeje, B. O. Ezema, S. Eze","doi":"10.17159/sajs.2024/15969","DOIUrl":"https://doi.org/10.17159/sajs.2024/15969","url":null,"abstract":"Pesticide residues and heavy metal content of cassava, yam, cocoyam, potato, water yam and carrot were evaluated by gas chromatography–mass spectrometry and atomic absorption spectroscopy. The detected pesticide residues in the samples were 2,4-dichlorophenoxyacetic acid, glyphosate, hexachlorobenzene (HCB), dichlorobiphenyl, aldrin, endosulfan, profenofos, g-chlordane, carbofuran, biphenyl, heptachlor, lindane and t-Nonachlor. The concentration of HCB ranged between 0.0799 ± 0.06 mg/kg and 0.1596 ± 0.00 mg/kg, which was greater than the permitted maximum limit of 0.5 mg/kg established by the US Environmental Protection Agency. The concentration of aldrin and profenofos detected was lower than the predetermined maximum allowed limits. Endosulfan concentrations in cocoyam (0.2500 mg/kg) and potato (0.3265 mg/kg) were higher than the limits allowed by the Canadian Department of Industrial Research. The heavy metals detected in these samples include cobalt, nickel, lead, manganese, chromium, arsenic and mercury in at least one of the samples evaluated. There was not much difference between the concentration of cobalt in yam (0.036 mg/kg) and the maximum allowed concentration (0.043 mg/kg). Lead was detected in potatoes and carrots but was below detectable concentration in cassava, yam, cocoyam and water yam. Similarly, cocoyam was found to have a significant mercury content (0.658 mg/kg), but mercury content was below detectable concentrations in cassava, yam and water yam.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140377328","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}
Pub Date : 2024-03-27DOI: 10.17159/sajs.2024/17299
Jacob S.T. Dlamini
{"title":"Ian Glenn’s ‘Wildlife Documentaries in Southern Africa: From East to South’","authors":"Jacob S.T. Dlamini","doi":"10.17159/sajs.2024/17299","DOIUrl":"https://doi.org/10.17159/sajs.2024/17299","url":null,"abstract":"","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140375091","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}
Pub Date : 2024-03-27DOI: 10.17159/sajs.2024/15837
Q. Chukwudum
The structure of climate finance flows from donors (multilateral sources) to recipients (sub-Saharan African countries) was studied. This is the first study to provide a comprehensive network structure of the climate finance flows into Africa, based on the global public climate finance governance system. Network theory and decision tree techniques were employed. The results obtained generally fit the multilateral funding units (MFUs) into two categories: central funding units (CFUs), which simultaneously attend to the climate-related projects of many African countries, and the boundary funding units (BFUs), which cater to only a few countries at once. An isolated region with no BFUs was identified. African countries within this group could be more exposed to climate financial risk as they rely on only the CFUs. In general, with the exception of mitigation REDD (reducing emissions from deforestation and forest degradation) climate finance, a disproportionate distribution of climate themes, with particular reference to adaptation finance, was observed across sub-Saharan Africa. This has real implications for equitable resource allocation of climate funds. The need for African-bred region-wide MFUs is recommended.
{"title":"Climate finance across sub-Saharan Africa: Decision trees and network flows","authors":"Q. Chukwudum","doi":"10.17159/sajs.2024/15837","DOIUrl":"https://doi.org/10.17159/sajs.2024/15837","url":null,"abstract":"The structure of climate finance flows from donors (multilateral sources) to recipients (sub-Saharan African countries) was studied. This is the first study to provide a comprehensive network structure of the climate finance flows into Africa, based on the global public climate finance governance system. Network theory and decision tree techniques were employed. The results obtained generally fit the multilateral funding units (MFUs) into two categories: central funding units (CFUs), which simultaneously attend to the climate-related projects of many African countries, and the boundary funding units (BFUs), which cater to only a few countries at once. An isolated region with no BFUs was identified. African countries within this group could be more exposed to climate financial risk as they rely on only the CFUs. In general, with the exception of mitigation REDD (reducing emissions from deforestation and forest degradation) climate finance, a disproportionate distribution of climate themes, with particular reference to adaptation finance, was observed across sub-Saharan Africa. This has real implications for equitable resource allocation of climate funds. The need for African-bred region-wide MFUs is recommended.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140376321","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}
Pub Date : 2024-03-27DOI: 10.17159/sajs.2024/17840
Mondli Hlatshwayo
{"title":"From casting to recasting: Reviewing the Recasting of Workers’ Power","authors":"Mondli Hlatshwayo","doi":"10.17159/sajs.2024/17840","DOIUrl":"https://doi.org/10.17159/sajs.2024/17840","url":null,"abstract":"","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140375018","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}
Pub Date : 2024-03-27DOI: 10.17159/sajs.2024/17841
Mesias Alfeus
The move away from LIBOR to new risk-free rates is crucial in finance. In this Commentary, I examine South Africa’s readiness for transitioning from JIBAR to these new rates,
{"title":"Navigating the JIBAR transition: Progress, impacts, readiness, and analytical insights","authors":"Mesias Alfeus","doi":"10.17159/sajs.2024/17841","DOIUrl":"https://doi.org/10.17159/sajs.2024/17841","url":null,"abstract":"The move away from LIBOR to new risk-free rates is crucial in finance. In this Commentary, I examine South Africa’s readiness for transitioning from JIBAR to these new rates,","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140373714","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}
Pub Date : 2024-03-27DOI: 10.17159/sajs.2024/16991
M. Pretorius
postmortem. However, when it comes to their prehistoric ancestors, our knowledge is limited to speculation and educated conjecture
死后。然而,说到它们的史前祖先,我们的知识仅限于猜测和有根据的推断
{"title":"The elusive echo: The mystery of Africa’s sparse bat fossil record","authors":"M. Pretorius","doi":"10.17159/sajs.2024/16991","DOIUrl":"https://doi.org/10.17159/sajs.2024/16991","url":null,"abstract":"postmortem. However, when it comes to their prehistoric ancestors, our knowledge is limited to speculation and educated conjecture","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140378075","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}
Pub Date : 2024-03-27DOI: 10.17159/sajs.2024/17008
Douglas A. Parry
{"title":"Without access to social media platform data, we risk being left in the dark","authors":"Douglas A. Parry","doi":"10.17159/sajs.2024/17008","DOIUrl":"https://doi.org/10.17159/sajs.2024/17008","url":null,"abstract":"","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140374106","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}
Pub Date : 2024-03-27DOI: 10.17159/sajs.2024/16043
J. A. Kruger, S. Roffe, A. J. van der Walt
Over regions with sparse observation networks, including South Africa’s Northern Cape Province, gridded data sets represent valuable supplementary data sources enabling spatially detailed climate investigations. Their performance is, however, influenced by regional characteristics, thus a performance assessment should be a prerequisite for any regional application. Through a pairwise comparison with eight point-based temperature records, we evaluated the AgERA5 data sets representation of mean summer (November–March; Tms) and winter (May–September; Tmw) temperatures and respective seasonal heatwave and coldwave characteristics across the Northern Cape for 1980–2020. Correlations ranging from 0.48 to 0.92 for Tms and from 0.38 to 0.94 for Tmw reflect relatively strong, but varying, temporal correspondence between the AgERA5 data and stations. Low biases, averaging −0.08 (0.17) °C and ranging from -0.79 to 2.10 (-0.40 to 1.47) °C for Tms (Tmw) were evident. Biases for the heatwave (coldwave) magnitudes were low, averaging -0.38 (0.19) °C2, and ranging from -1.55 to 1.47 (-2.05 to 2.91) °C2. Biases for the heatwave (coldwave) frequency were also low, but typically overestimated, averaging 1.19 (0.73) days, and ranging from -1.33 to 5.60 (-1.61 to 3.39) days. Biases for the heatwave (coldwave) number were low and typically overestimated, averaging 0.27 (0.08) events, and ranging from -0.28 to 1.40 (-0.39 to 0.39) events. Despite some stations depicting consistently poor performance, the study results support further application of the AgERA5 product for spatiotemporal analyses of mean and extreme temperatures across the Northern Cape, provided limitations are adequately acknowledged. Further application of the fine-resolution AgERA5 product will greatly inform impact-based studies exploring mean and extreme temperature influences over the Northern Cape Province.
{"title":"AgERA5 representation of seasonal mean and extreme temperatures in the Northern Cape, South Africa","authors":"J. A. Kruger, S. Roffe, A. J. van der Walt","doi":"10.17159/sajs.2024/16043","DOIUrl":"https://doi.org/10.17159/sajs.2024/16043","url":null,"abstract":"Over regions with sparse observation networks, including South Africa’s Northern Cape Province, gridded data sets represent valuable supplementary data sources enabling spatially detailed climate investigations. Their performance is, however, influenced by regional characteristics, thus a performance assessment should be a prerequisite for any regional application. Through a pairwise comparison with eight point-based temperature records, we evaluated the AgERA5 data sets representation of mean summer (November–March; Tms) and winter (May–September; Tmw) temperatures and respective seasonal heatwave and coldwave characteristics across the Northern Cape for 1980–2020. Correlations ranging from 0.48 to 0.92 for Tms and from 0.38 to 0.94 for Tmw reflect relatively strong, but varying, temporal correspondence between the AgERA5 data and stations. Low biases, averaging −0.08 (0.17) °C and ranging from -0.79 to 2.10 (-0.40 to 1.47) °C for Tms (Tmw) were evident. Biases for the heatwave (coldwave) magnitudes were low, averaging -0.38 (0.19) °C2, and ranging from -1.55 to 1.47 (-2.05 to 2.91) °C2. Biases for the heatwave (coldwave) frequency were also low, but typically overestimated, averaging 1.19 (0.73) days, and ranging from -1.33 to 5.60 (-1.61 to 3.39) days. Biases for the heatwave (coldwave) number were low and typically overestimated, averaging 0.27 (0.08) events, and ranging from -0.28 to 1.40 (-0.39 to 0.39) events. Despite some stations depicting consistently poor performance, the study results support further application of the AgERA5 product for spatiotemporal analyses of mean and extreme temperatures across the Northern Cape, provided limitations are adequately acknowledged. Further application of the fine-resolution AgERA5 product will greatly inform impact-based studies exploring mean and extreme temperature influences over the Northern Cape Province.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140377583","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}
Pub Date : 2024-03-27DOI: 10.17159/sajs.2024/16301
Maxine J. Turner, Sandy van Vuuren, Stephanie Leigh-de Rapper
In the South African public healthcare sector, 28% of diabetic patients present to primary healthcare clinics with diabetic foot ulcers (DFUs), often presenting in advanced stages of ulcer severity. In this study, we aimed to categorise factors predisposing individuals to developing a DFU and to identify the potential shortcomings in existing treatment plans in the South African healthcare system. In addition, the use of preventative measures in the management of DFUs was examined as well as the influence of past treatment practices. A total minimum sample size of 50 DFUs was required for this study. Participants who were selected for this study had their past records reviewed in order to determine the likelihood of previous DFU infections, as well as to determine the occurrence of co-morbidities. The treatment protocol implemented was recorded. Twelve-month patient records were used to identify the infection frequency and past treatment protocols. A total of 48.9% of patients reported that they did not make use of any preventative measures. The most frequent concurrent medical conditions were hypertension, dyslipidaemia, and peripheral neuropathy. Polypharmacy was prevalent, with 55% of the population prescribed five or more medications. Potential medication interactions were examined and a total of 210 interactions were documented. An analysis of past and current treatment practices revealed that 52.1% of the treatment protocols did not comply with local treatment guidelines. This study highlights the urgent need for updated DFU treatment protocols in relation to the overall management of DFUs, taking into account existing international guidelines.
{"title":"Analysing patient factors and treatment impact on diabetic foot ulcers in South Africa","authors":"Maxine J. Turner, Sandy van Vuuren, Stephanie Leigh-de Rapper","doi":"10.17159/sajs.2024/16301","DOIUrl":"https://doi.org/10.17159/sajs.2024/16301","url":null,"abstract":"In the South African public healthcare sector, 28% of diabetic patients present to primary healthcare clinics with diabetic foot ulcers (DFUs), often presenting in advanced stages of ulcer severity. In this study, we aimed to categorise factors predisposing individuals to developing a DFU and to identify the potential shortcomings in existing treatment plans in the South African healthcare system. In addition, the use of preventative measures in the management of DFUs was examined as well as the influence of past treatment practices. A total minimum sample size of 50 DFUs was required for this study. Participants who were selected for this study had their past records reviewed in order to determine the likelihood of previous DFU infections, as well as to determine the occurrence of co-morbidities. The treatment protocol implemented was recorded. Twelve-month patient records were used to identify the infection frequency and past treatment protocols. A total of 48.9% of patients reported that they did not make use of any preventative measures. The most frequent concurrent medical conditions were hypertension, dyslipidaemia, and peripheral neuropathy. Polypharmacy was prevalent, with 55% of the population prescribed five or more medications. Potential medication interactions were examined and a total of 210 interactions were documented. An analysis of past and current treatment practices revealed that 52.1% of the treatment protocols did not comply with local treatment guidelines. This study highlights the urgent need for updated DFU treatment protocols in relation to the overall management of DFUs, taking into account existing international guidelines.","PeriodicalId":21928,"journal":{"name":"South African Journal of Science","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140374368","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}