Population genetics of invasive and native Nymphaea mexicana Zuccarini: Taking the first steps to initiate a biological control programme in South Africa
- Reid, Megan K, Naidu, Prinavin, Paterson, Iain D, Mangan, Rosie, Coetzee, Julie A
- Authors: Reid, Megan K , Naidu, Prinavin , Paterson, Iain D , Mangan, Rosie , Coetzee, Julie A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419375 , vital:71638 , xlink:href="https://doi.org/10.1016/j.aquabot.2021.103372"
- Description: Nymphaea mexicana Zuccarini (Nympheaceae) (Mexican waterlily) is a rooted floating-leaved aquatic plant native to southern USA and Mexico that has become a problematic invasive alien plant in South Africa. Biological control is considered a desirable management strategy for the plant in South Africa. A good understanding of the genetic structure of invasive populations has been useful in other biological control programmes because taxonomic uncertainty about the target plant can result in natural enemies that are not adapted to the invasive populations being considered as potential agents. For N. mexicana, hybrids exist in the wild and horticultural trade, but identification is difficult, so understanding the genetic structure of populations is required to ensure that potential agents are collected off plants similar to invasive populations in South Africa. ISSR (inter-simple sequence repeats) analysis was used to determine whether invasive N. mexicana populations from South Africa were genetically similar to native range populations from USA or whether they were hybrids. Results from these analyses were matched with the morphotypes of each population based on petal colour, shape, and size. The genotypes suggested by the ISSR analyses corroborated the presence of both hybrid and pure forms of N. mexicana in South Africa. Populations of N. mexicana in the invaded range that are genetically similar to native range populations are more likely to be suitable for biological control, while other populations are likely to be hybrids formed by crossing of parents from the native range or within the horticultural trade, which may present difficulties for management using biocontrol.
- Full Text:
- Authors: Reid, Megan K , Naidu, Prinavin , Paterson, Iain D , Mangan, Rosie , Coetzee, Julie A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419375 , vital:71638 , xlink:href="https://doi.org/10.1016/j.aquabot.2021.103372"
- Description: Nymphaea mexicana Zuccarini (Nympheaceae) (Mexican waterlily) is a rooted floating-leaved aquatic plant native to southern USA and Mexico that has become a problematic invasive alien plant in South Africa. Biological control is considered a desirable management strategy for the plant in South Africa. A good understanding of the genetic structure of invasive populations has been useful in other biological control programmes because taxonomic uncertainty about the target plant can result in natural enemies that are not adapted to the invasive populations being considered as potential agents. For N. mexicana, hybrids exist in the wild and horticultural trade, but identification is difficult, so understanding the genetic structure of populations is required to ensure that potential agents are collected off plants similar to invasive populations in South Africa. ISSR (inter-simple sequence repeats) analysis was used to determine whether invasive N. mexicana populations from South Africa were genetically similar to native range populations from USA or whether they were hybrids. Results from these analyses were matched with the morphotypes of each population based on petal colour, shape, and size. The genotypes suggested by the ISSR analyses corroborated the presence of both hybrid and pure forms of N. mexicana in South Africa. Populations of N. mexicana in the invaded range that are genetically similar to native range populations are more likely to be suitable for biological control, while other populations are likely to be hybrids formed by crossing of parents from the native range or within the horticultural trade, which may present difficulties for management using biocontrol.
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Push-pull type Co (III) corroles
- Niu, Yingjie, Zhu, Weihua, Mack, John, Dubazana, Nadine, Nyokong, Tebello, Fu, Bo, Xu, Haijun, Liang, Xu
- Authors: Niu, Yingjie , Zhu, Weihua , Mack, John , Dubazana, Nadine , Nyokong, Tebello , Fu, Bo , Xu, Haijun , Liang, Xu
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190826 , vital:45032 , xlink:href="https://doi.org/10.1142/S1088424621500279"
- Description: The rational design and preparation of three A2B type Co(III)triarylcorroles with push- and pull-substituents are reported. The structure-property relationships were identified by comparing their optically spectroscopic and electrochemical properties to trends predicted in DFT and TD-DFT calculations. The results demonstrate that the Co(III)triarylcorroles are highly efficient catalysts for electrocatalyzed hydrogen evolutions (HERs) and oxygen reductions (ORRs), and that their reactivity can be modulated by changing the meso-B-substituent of the Co(III)Corroles.
- Full Text:
- Authors: Niu, Yingjie , Zhu, Weihua , Mack, John , Dubazana, Nadine , Nyokong, Tebello , Fu, Bo , Xu, Haijun , Liang, Xu
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190826 , vital:45032 , xlink:href="https://doi.org/10.1142/S1088424621500279"
- Description: The rational design and preparation of three A2B type Co(III)triarylcorroles with push- and pull-substituents are reported. The structure-property relationships were identified by comparing their optically spectroscopic and electrochemical properties to trends predicted in DFT and TD-DFT calculations. The results demonstrate that the Co(III)triarylcorroles are highly efficient catalysts for electrocatalyzed hydrogen evolutions (HERs) and oxygen reductions (ORRs), and that their reactivity can be modulated by changing the meso-B-substituent of the Co(III)Corroles.
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Synthesis and trypanocidal activity of substituted 2, 4-diarylquinoline derivatives
- Oluwafemi, Kola A, Phunguphungu, Siyolise, Gqunu, Sinalo, Isaacs, Michelle, Hoppe, Heinrich C, Klein, Rosalyn, Kaye, Perry T
- Authors: Oluwafemi, Kola A , Phunguphungu, Siyolise , Gqunu, Sinalo , Isaacs, Michelle , Hoppe, Heinrich C , Klein, Rosalyn , Kaye, Perry T
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/477683 , vital:78111 , xlink:href="https://doi.org/10.24820/ark.5550190.p011.499"
- Description: A small library of nine, novel 2, 4-diarylquinoline derivatives has been prepared in high yield via convenient one-or two-step routes from a series of substituted 2-aminobenzophenones. None of the products exhibited toxicity at 20 μM against human cervix adenocarcinoma (HeLa) cells, while many of them exhibited encouraging trypanocidal activity against T. brucei brucei (a parasite responsible for African cattle trypanosomiasis)-some with IC50 values in the range 2.8–6.2 μM.
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- Authors: Oluwafemi, Kola A , Phunguphungu, Siyolise , Gqunu, Sinalo , Isaacs, Michelle , Hoppe, Heinrich C , Klein, Rosalyn , Kaye, Perry T
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/477683 , vital:78111 , xlink:href="https://doi.org/10.24820/ark.5550190.p011.499"
- Description: A small library of nine, novel 2, 4-diarylquinoline derivatives has been prepared in high yield via convenient one-or two-step routes from a series of substituted 2-aminobenzophenones. None of the products exhibited toxicity at 20 μM against human cervix adenocarcinoma (HeLa) cells, while many of them exhibited encouraging trypanocidal activity against T. brucei brucei (a parasite responsible for African cattle trypanosomiasis)-some with IC50 values in the range 2.8–6.2 μM.
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Terminaliamide, a new ceramide and other phytoconstituents from the roots of Terminalia mantaly H. Perrier and their biological activities
- Mbosso, Emmanuel, Siwe-Noundou, Xavier, Fannang, Simone V, Song, Achille M, Assob, Jules C N, Hoppe, Heinrich C, Krause, Rui W M
- Authors: Mbosso, Emmanuel , Siwe-Noundou, Xavier , Fannang, Simone V , Song, Achille M , Assob, Jules C N , Hoppe, Heinrich C , Krause, Rui W M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191779 , vital:45163 , xlink:href="https://doi.org/10.1080/14786419.2019.1647425"
- Description: Terminaliamide (1), a new ceramide was isolated from the roots of Terminalia mantaly H. Perrier (Combretaceae) along with 4 known compounds (2–5). The structures of the compounds were elucidated using 1D and 2D NMR spectroscopy analysis and mass spectrometry. Compound 1 exhibited moderated antibacterial activity towards Staphylococcus aureus with MIC value of 62.5 μg/mL. The crude MeOH extract (TMr) highly reduced Plasmodium falciparum growth with an IC50 value of 10.11 μg/mL, while hexane fraction (F1) highly reduced Trypanosoma brucei brucei growth with an IC50 value of 5.60 µg/mL. All tested samples presented little or no in vitro cytotoxicity on HeLa cell line. The present work confirms that T. mantaly is medicinally important and may be used effectively as an antimicrobial, an antiplasmodial and an antitrypanosomial with promising therapeutic index.
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- Authors: Mbosso, Emmanuel , Siwe-Noundou, Xavier , Fannang, Simone V , Song, Achille M , Assob, Jules C N , Hoppe, Heinrich C , Krause, Rui W M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191779 , vital:45163 , xlink:href="https://doi.org/10.1080/14786419.2019.1647425"
- Description: Terminaliamide (1), a new ceramide was isolated from the roots of Terminalia mantaly H. Perrier (Combretaceae) along with 4 known compounds (2–5). The structures of the compounds were elucidated using 1D and 2D NMR spectroscopy analysis and mass spectrometry. Compound 1 exhibited moderated antibacterial activity towards Staphylococcus aureus with MIC value of 62.5 μg/mL. The crude MeOH extract (TMr) highly reduced Plasmodium falciparum growth with an IC50 value of 10.11 μg/mL, while hexane fraction (F1) highly reduced Trypanosoma brucei brucei growth with an IC50 value of 5.60 µg/mL. All tested samples presented little or no in vitro cytotoxicity on HeLa cell line. The present work confirms that T. mantaly is medicinally important and may be used effectively as an antimicrobial, an antiplasmodial and an antitrypanosomial with promising therapeutic index.
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The influence of biophysical and socio-economic factors on the effectiveness of private land conservation areas in preventing natural land cover loss across South Africa
- Shumba, Tafadzwa, de Vos, Alta, Biggs, Reinette, Esler, Karen J, Clements, Hayley S
- Authors: Shumba, Tafadzwa , de Vos, Alta , Biggs, Reinette , Esler, Karen J , Clements, Hayley S
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415940 , vital:71302 , xlink:href="https://doi.org/10.1016/j.gecco.2021.e01670"
- Description: There is increasing interest in the potential of private land conservation areas (PLCAs) as a complementary biodiversity conservation strategy to state-owned protected areas. However, there is limited understanding of how the diverse social-ecological contexts of PLCAs influence their effectiveness in conserving biodiversity. Here, we investigated how the effectiveness of South African PLCAs in conserving biodiversity varied across social-ecological contexts, using natural land cover as a proxy. Social-ecological contexts were represented by biophysical and legal factors (distance to towns and roads, elevation, slope, terrain ruggedness, rainfall, PLCA size, distance to state-owned national parks, and presence of legal protection) and, for a subset of commercially-operated PLCAs, management factors (adopted business model, and profitability).
- Full Text:
- Authors: Shumba, Tafadzwa , de Vos, Alta , Biggs, Reinette , Esler, Karen J , Clements, Hayley S
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415940 , vital:71302 , xlink:href="https://doi.org/10.1016/j.gecco.2021.e01670"
- Description: There is increasing interest in the potential of private land conservation areas (PLCAs) as a complementary biodiversity conservation strategy to state-owned protected areas. However, there is limited understanding of how the diverse social-ecological contexts of PLCAs influence their effectiveness in conserving biodiversity. Here, we investigated how the effectiveness of South African PLCAs in conserving biodiversity varied across social-ecological contexts, using natural land cover as a proxy. Social-ecological contexts were represented by biophysical and legal factors (distance to towns and roads, elevation, slope, terrain ruggedness, rainfall, PLCA size, distance to state-owned national parks, and presence of legal protection) and, for a subset of commercially-operated PLCAs, management factors (adopted business model, and profitability).
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A systematic analysis of doctoral publication trends in South Africa
- Van Schalkwyk, Susan, Mouton, Johann, Redelinghuys, Herman, McKenna, Sioux
- Authors: Van Schalkwyk, Susan , Mouton, Johann , Redelinghuys, Herman , McKenna, Sioux
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185826 , vital:44438 , xlink:href="http://dx.doi.org/10.17159/sajs.2020/7926"
- Description: It is incumbent upon doctoral students that their work makes a substantive contribution to the field within which it is conducted. Dissemination of this work beyond the dissertation, whether whilst studying or after graduation, is necessary to ensure that the contribution does not remain largely dormant. While dissemination can take many forms, peer-reviewed journal articles are the key medium by which knowledge is shared. We aimed to establish the proportion of doctoral theses that results in journal publications by linking South African doctoral thesis metadata to journal articles authored by doctoral candidates. To effect this matching, a customised data set was created that comprised two large databases: the South African Theses Database (SATD), which documented all doctoral degrees awarded in South Africa (2005-2014), and the South African Knowledgebase (SAK), which listed all publications submitted for subsidy to the South African Department of Higher Education and Training (2005-2017). The process followed several iterations of matching and verification, including manual inspection of the data, in order to isolate only those records for which the link was established beyond doubt. Over the period under review, 47.6% of graduates, representing 22 of the 26 higher education institutions, published at least one journal article. Results further indicate increasingly higher publication rates over time. To explore whether the journal article identified was a direct product of the study, a similarity index was developed. Over 75% of records demonstrated high similarity. While the trend towards increasing publications by graduates is promising, work in this area should be ongoing. In spite of increasing trends in publications by graduates, many are not disseminating their work, suggesting that significant bodies of research are potentially not being shared with the academic community and are therefore not contributing to the relevant discipline or field. •This study provides baseline data from which a number of further investigations can be launched, such as exploring the extent to which doctoral candidates who are also academics are publishing their work; the factors that enable or constrain publication; the other avenues of dissemination used; and whether publishing or not publishing can serve as a proxy for the quality of the doctoral work.
- Full Text:
- Authors: Van Schalkwyk, Susan , Mouton, Johann , Redelinghuys, Herman , McKenna, Sioux
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185826 , vital:44438 , xlink:href="http://dx.doi.org/10.17159/sajs.2020/7926"
- Description: It is incumbent upon doctoral students that their work makes a substantive contribution to the field within which it is conducted. Dissemination of this work beyond the dissertation, whether whilst studying or after graduation, is necessary to ensure that the contribution does not remain largely dormant. While dissemination can take many forms, peer-reviewed journal articles are the key medium by which knowledge is shared. We aimed to establish the proportion of doctoral theses that results in journal publications by linking South African doctoral thesis metadata to journal articles authored by doctoral candidates. To effect this matching, a customised data set was created that comprised two large databases: the South African Theses Database (SATD), which documented all doctoral degrees awarded in South Africa (2005-2014), and the South African Knowledgebase (SAK), which listed all publications submitted for subsidy to the South African Department of Higher Education and Training (2005-2017). The process followed several iterations of matching and verification, including manual inspection of the data, in order to isolate only those records for which the link was established beyond doubt. Over the period under review, 47.6% of graduates, representing 22 of the 26 higher education institutions, published at least one journal article. Results further indicate increasingly higher publication rates over time. To explore whether the journal article identified was a direct product of the study, a similarity index was developed. Over 75% of records demonstrated high similarity. While the trend towards increasing publications by graduates is promising, work in this area should be ongoing. In spite of increasing trends in publications by graduates, many are not disseminating their work, suggesting that significant bodies of research are potentially not being shared with the academic community and are therefore not contributing to the relevant discipline or field. •This study provides baseline data from which a number of further investigations can be launched, such as exploring the extent to which doctoral candidates who are also academics are publishing their work; the factors that enable or constrain publication; the other avenues of dissemination used; and whether publishing or not publishing can serve as a proxy for the quality of the doctoral work.
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Analytical Detection and Electrocatalysis of Paracetamol in Aqueous Media Using Rare‐Earth Double‐Decker Phthalocyaninato Chelates as Electrochemically Active Materials
- Sekhosana, Kutloano E, Nkhahle, Reitumetse, Nyokong, Tebello
- Authors: Sekhosana, Kutloano E , Nkhahle, Reitumetse , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190840 , vital:45033 , xlink:href="https://doi.org/10.1002/slct.202002268"
- Description: Paracetamol (PA), being an analgesic and antipyretic medicine, can cause fatal hepatotoxicity and nephrotoxicity when overdosed. It is therefore important to develop electrochemical sensors that can monitor and quantify it in aquatic environments. In this study, rare-earth sandwich-type phthalocyaninato chelates based on neodymium (1 a) and samarium (1 b) were employed as electrocatalysts to modify glassy carbon electrodes (GCE) for the first time. It was found that 1 a-modified GCE (herein referred to as 1 a-GCE) is less conductive than 1 b-modified counterpart (1 b-GCE). A larger rate constant was also obtained for 1 b-GCE. It was established that a faster oxidation rate efficiency was responsible for lower limit of detection value obtained for 1 b-GCE as compared to 1 a-GCE.
- Full Text:
- Authors: Sekhosana, Kutloano E , Nkhahle, Reitumetse , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190840 , vital:45033 , xlink:href="https://doi.org/10.1002/slct.202002268"
- Description: Paracetamol (PA), being an analgesic and antipyretic medicine, can cause fatal hepatotoxicity and nephrotoxicity when overdosed. It is therefore important to develop electrochemical sensors that can monitor and quantify it in aquatic environments. In this study, rare-earth sandwich-type phthalocyaninato chelates based on neodymium (1 a) and samarium (1 b) were employed as electrocatalysts to modify glassy carbon electrodes (GCE) for the first time. It was found that 1 a-modified GCE (herein referred to as 1 a-GCE) is less conductive than 1 b-modified counterpart (1 b-GCE). A larger rate constant was also obtained for 1 b-GCE. It was established that a faster oxidation rate efficiency was responsible for lower limit of detection value obtained for 1 b-GCE as compared to 1 a-GCE.
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Assessment of taste masking of captopril by ion-exchange resins using electronic gustatory system
- Chikukwa, Mellisa T R, Wesoly, Malgorzata, Korzeniowska, Aleksandra B, Ciosek-Skibinska, Patrycja, Walker, Roderick B, Khamanga, Sandile M M
- Authors: Chikukwa, Mellisa T R , Wesoly, Malgorzata , Korzeniowska, Aleksandra B , Ciosek-Skibinska, Patrycja , Walker, Roderick B , Khamanga, Sandile M M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184710 , vital:44265 , xlink:href="https://doi.org/10.1080/10837450.2019.1687520"
- Description: The objective of the study was to mask the unpleasant taste of captopril (CPT). Taste masking was achieved by complexation of CPT with a basic ion exchange resin, Dowex® 66, using the batch method. Dowex® 66 was used for the adsorption of CPT, and physical and chemical parameters of the CPT resinates complex were evaluated. A central composite design was used to generate the experiments for the manufacture of resinates using different process and formulation variables. In vitro dissolution studies were performed for 2 h in 0.01N HCl (pH 1.6) using USP Apparatus I. The compatibility of CPT and the resin was evaluated by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD). The resinates were evaluated for micromeritic properties and further characterised using FTIR, DSC, and PXRD. Response surface methodology was used to determine the significance of input variables on the CPT content and release. The CPT resin ratio was found to have a significant impact on content of the resinates and on CPT release. The formulations were also studied for taste masking ability by means of an electronic gustatory system – electronic tongue.
- Full Text:
- Authors: Chikukwa, Mellisa T R , Wesoly, Malgorzata , Korzeniowska, Aleksandra B , Ciosek-Skibinska, Patrycja , Walker, Roderick B , Khamanga, Sandile M M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184710 , vital:44265 , xlink:href="https://doi.org/10.1080/10837450.2019.1687520"
- Description: The objective of the study was to mask the unpleasant taste of captopril (CPT). Taste masking was achieved by complexation of CPT with a basic ion exchange resin, Dowex® 66, using the batch method. Dowex® 66 was used for the adsorption of CPT, and physical and chemical parameters of the CPT resinates complex were evaluated. A central composite design was used to generate the experiments for the manufacture of resinates using different process and formulation variables. In vitro dissolution studies were performed for 2 h in 0.01N HCl (pH 1.6) using USP Apparatus I. The compatibility of CPT and the resin was evaluated by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD). The resinates were evaluated for micromeritic properties and further characterised using FTIR, DSC, and PXRD. Response surface methodology was used to determine the significance of input variables on the CPT content and release. The CPT resin ratio was found to have a significant impact on content of the resinates and on CPT release. The formulations were also studied for taste masking ability by means of an electronic gustatory system – electronic tongue.
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Contradictions in womxn’s experiences of pre-abortion counselling in South Africa: Implications for client‐centred practice
- Mavuso, Jabulile M-J J, Macleod, Catriona I
- Authors: Mavuso, Jabulile M-J J , Macleod, Catriona I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443638 , vital:74140 , xlink:href="https://doi.org/10.1111/nin.12330"
- Description: Pre-abortion counselling may play a key role in abortion seekers’ understanding of their decision to terminate a pregnancy and the subsequent emotions that they feel. In this paper, we report on a study conducted in the Eastern Cape province of South Africa concerning womxn's experiences of the pre-abortion counselling offered as part of the implementation of the Choice of Termination Act that governs the provision of legal abortion in the country. Using a narrative-discursive lens, the analysis revealed four micro-narratives in which participants appreciated non-directive and empathic counselling, as well as being provided with information. They also indicated that the counselling was upsetting and hurtful, particularly when providers drew on the awfulisation of abortion discourse to suggest that abortion leads to terrible consequences, and foetal personhood discourse to intimate that terminating the pregnancy is wrong and other alternatives (adoption, parenting) are better. The connection between these broadly positive and negative responses may lie in the dominance of anti-abortion discourses coupled with the powerful positioning of healthcare providers as experts. The attendant disempowerment of clients within the health clinic setting may constrain pregnant people's ability to question such ‘expert’ information. The implications for feminist client-centred pre-abortion counselling are discussed.
- Full Text:
- Authors: Mavuso, Jabulile M-J J , Macleod, Catriona I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443638 , vital:74140 , xlink:href="https://doi.org/10.1111/nin.12330"
- Description: Pre-abortion counselling may play a key role in abortion seekers’ understanding of their decision to terminate a pregnancy and the subsequent emotions that they feel. In this paper, we report on a study conducted in the Eastern Cape province of South Africa concerning womxn's experiences of the pre-abortion counselling offered as part of the implementation of the Choice of Termination Act that governs the provision of legal abortion in the country. Using a narrative-discursive lens, the analysis revealed four micro-narratives in which participants appreciated non-directive and empathic counselling, as well as being provided with information. They also indicated that the counselling was upsetting and hurtful, particularly when providers drew on the awfulisation of abortion discourse to suggest that abortion leads to terrible consequences, and foetal personhood discourse to intimate that terminating the pregnancy is wrong and other alternatives (adoption, parenting) are better. The connection between these broadly positive and negative responses may lie in the dominance of anti-abortion discourses coupled with the powerful positioning of healthcare providers as experts. The attendant disempowerment of clients within the health clinic setting may constrain pregnant people's ability to question such ‘expert’ information. The implications for feminist client-centred pre-abortion counselling are discussed.
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Dietary fatty acids of spiders reveal spatial and temporal variations in aquatic-terrestrial linkages
- Chari, Lenin D, Richoux, Nicole B, Moyo, Sydney, Villet, Martin H
- Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454320 , vital:75335 , xlink:href="https://doi.org/10.1016/j.fooweb.2020.e00152"
- Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
- Full Text:
- Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454320 , vital:75335 , xlink:href="https://doi.org/10.1016/j.fooweb.2020.e00152"
- Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
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Do spotted hyaenas outcompete the big cats in a small, enclosed system in South Africa?
- Comley, Jessica, Joubert, Christoffel J, Mgqatsa, Nokubonga, Parker, Daniel M
- Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/462603 , vital:76318 , xlink:href="https://doi.org/10.1111/jzo.12772"
- Description: Carnivores are adapted to kill, meaning sympatric carnivores can have particularly aggressive and harmful competitive interactions. The co‐existence of multiple carnivores in an ecosystem could be restricted by their similarity in ecological niches (e.g. dietary overlap); however, high prey abundances could facilitate their co‐existence. Although the development of small, enclosed reserves (larger than 400 km2) in South Africa has reduced human–carnivore conflict, these systems may increase the likelihood of carnivore intra‐guild competition due to the clumping of competing carnivores into these restricted spaces. Using carnivore scat and kill site analyses, we determined the dietary preferences and overlap of sympatric large carnivores in a small, enclosed reserve, Selati Game Reserve (Selati). Large carnivores in Selati (lions (Panthera leo), spotted hyaenas (Crocuta crocuta) and leopards (Panthera pardus)) preferentially selected for varying combinations of prey size classes. Lions selected for large prey, leopards selected for small prey and spotted hyaenas did not prefer any particular prey size. Additionally, lions had the largest dietary breadth and the diet of leopards and spotted hyaenas overlapped considerably. Coupled with high prey densities in Selati, the predation strategies of the large carnivores could be facilitating their co‐existence. On the other hand, the high degree of dietary overlap among large carnivores suggests that there is strong potential for exploitation competition, particularly between spotted hyaenas and leopards as their diet overlapped extensively (91% and 93% for prey species and size class, respectively). Although spotted hyaenas are potentially outcompeting leopards in Selati, lions were the most dominant large carnivore. Our study reiterates the complexity of carnivore guild interactions and emphasizes how these interactions are subject to variation due to site‐specific circumstances (e.g. composition of prey and carnivore populations). We therefore encourage site‐specific, multi‐carnivore research throughout protected areas in southern Africa.
- Full Text:
- Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/462603 , vital:76318 , xlink:href="https://doi.org/10.1111/jzo.12772"
- Description: Carnivores are adapted to kill, meaning sympatric carnivores can have particularly aggressive and harmful competitive interactions. The co‐existence of multiple carnivores in an ecosystem could be restricted by their similarity in ecological niches (e.g. dietary overlap); however, high prey abundances could facilitate their co‐existence. Although the development of small, enclosed reserves (larger than 400 km2) in South Africa has reduced human–carnivore conflict, these systems may increase the likelihood of carnivore intra‐guild competition due to the clumping of competing carnivores into these restricted spaces. Using carnivore scat and kill site analyses, we determined the dietary preferences and overlap of sympatric large carnivores in a small, enclosed reserve, Selati Game Reserve (Selati). Large carnivores in Selati (lions (Panthera leo), spotted hyaenas (Crocuta crocuta) and leopards (Panthera pardus)) preferentially selected for varying combinations of prey size classes. Lions selected for large prey, leopards selected for small prey and spotted hyaenas did not prefer any particular prey size. Additionally, lions had the largest dietary breadth and the diet of leopards and spotted hyaenas overlapped considerably. Coupled with high prey densities in Selati, the predation strategies of the large carnivores could be facilitating their co‐existence. On the other hand, the high degree of dietary overlap among large carnivores suggests that there is strong potential for exploitation competition, particularly between spotted hyaenas and leopards as their diet overlapped extensively (91% and 93% for prey species and size class, respectively). Although spotted hyaenas are potentially outcompeting leopards in Selati, lions were the most dominant large carnivore. Our study reiterates the complexity of carnivore guild interactions and emphasizes how these interactions are subject to variation due to site‐specific circumstances (e.g. composition of prey and carnivore populations). We therefore encourage site‐specific, multi‐carnivore research throughout protected areas in southern Africa.
- Full Text:
Double-and quintuple-decker phthalocyaninato chelates as optical limiters in solution and thin film
- Sekhosana, Kutloano E, Nyokong, Tebello
- Authors: Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186733 , vital:44529 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107836"
- Description: The rare-earth quintuple-decker phthalocyaninato chelates (3a and 3b) were synthesized from their parent rare-earth double-decker phthalocyaninato precursors (2b and 2a). After extensive structural elucidation, these complexes were subjected to various spectroscopic techniques to investigate their electronic behavior. It was found that complexes 3a and 3b existed as the oxidized forms. When investigating the optical limiting properties, all these complexes were found to exhibit reverse saturable absorption, with complex 2a showing a more enhanced open-aperture Z-Scan signature than complex 2b. Interestingly, complexes 3a and 3b (in solution) exhibited better open-aperture Z-Scan signatures than their parent rare-earth double-decker phthalocyaninato precursors (2b and 2a). However, thin films fabricated from these complexes did not show an improvement in the optical limiting properties when compared to 2a, 3a, 3b except for that which was prepared from 2b. This study shows the importance of extensive π-electron system in phthalocyaninato complexes for optical limiting applications.
- Full Text:
- Authors: Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186733 , vital:44529 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107836"
- Description: The rare-earth quintuple-decker phthalocyaninato chelates (3a and 3b) were synthesized from their parent rare-earth double-decker phthalocyaninato precursors (2b and 2a). After extensive structural elucidation, these complexes were subjected to various spectroscopic techniques to investigate their electronic behavior. It was found that complexes 3a and 3b existed as the oxidized forms. When investigating the optical limiting properties, all these complexes were found to exhibit reverse saturable absorption, with complex 2a showing a more enhanced open-aperture Z-Scan signature than complex 2b. Interestingly, complexes 3a and 3b (in solution) exhibited better open-aperture Z-Scan signatures than their parent rare-earth double-decker phthalocyaninato precursors (2b and 2a). However, thin films fabricated from these complexes did not show an improvement in the optical limiting properties when compared to 2a, 3a, 3b except for that which was prepared from 2b. This study shows the importance of extensive π-electron system in phthalocyaninato complexes for optical limiting applications.
- Full Text:
Forays into contemporary South African theatre
- Authors: Krueger, Anton
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229578 , vital:49689 , xlink:href="https://doi.org/10.1080/10137548.2021.1963112"
- Description: Trying to keep up with what is going on in South African theatre today is an endlessly renewing process. The word ‘foray’ has associations of brief incursions into foreign territory. It’s an almost hesitant word, a venture into unexplored terrain. This hesitation feels apt in the sense that (at the time of writing), any description of a pre-Covid theatre is bound to feel strange. The landscape has shifted, and nobody is quite sure how things will look in a year from now. Nevertheless, this is a rich compendium of relatively recent theatre, as seen from within the country and also from the vantage of a global perspective. Almost all of the essays are drawn from a 2017 conference held in Brussels at the Université Libre de Bruxelles, called: ‘New Stage Idioms: South African Drama, Theatre and Performance in the Twenty-first Century.’Although the tone remains scholarly, the inclusion of different kinds of writers – not only academics but activists, playwrights and journalists – prevents the work from becoming overly dry.
- Full Text:
- Authors: Krueger, Anton
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229578 , vital:49689 , xlink:href="https://doi.org/10.1080/10137548.2021.1963112"
- Description: Trying to keep up with what is going on in South African theatre today is an endlessly renewing process. The word ‘foray’ has associations of brief incursions into foreign territory. It’s an almost hesitant word, a venture into unexplored terrain. This hesitation feels apt in the sense that (at the time of writing), any description of a pre-Covid theatre is bound to feel strange. The landscape has shifted, and nobody is quite sure how things will look in a year from now. Nevertheless, this is a rich compendium of relatively recent theatre, as seen from within the country and also from the vantage of a global perspective. Almost all of the essays are drawn from a 2017 conference held in Brussels at the Université Libre de Bruxelles, called: ‘New Stage Idioms: South African Drama, Theatre and Performance in the Twenty-first Century.’Although the tone remains scholarly, the inclusion of different kinds of writers – not only academics but activists, playwrights and journalists – prevents the work from becoming overly dry.
- Full Text:
Green synthesis of antimicrobial silver nanoparticles using aqueous leaf extracts from three Congolese plant species (Brillantaisia patula, Crossopteryx febrifuga and Senna siamea)
- Kambale, Espoir K, Nkanga, Christian I, Mutonkole, Blaise-Pascal I, Bapolisi, Alain M, Tassa, Daniel O, Liesse, Jean-Marie I, Krause, Rui W M, Memvanga, Patrick B
- Authors: Kambale, Espoir K , Nkanga, Christian I , Mutonkole, Blaise-Pascal I , Bapolisi, Alain M , Tassa, Daniel O , Liesse, Jean-Marie I , Krause, Rui W M , Memvanga, Patrick B
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193419 , vital:45330 , xlink:href="https://doi.org/10.1016/j.heliyon.2020.e04493"
- Description: In the present study, silver nanoparticles (AgNPs) were synthesized using aqueous leaf extracts of three Congolese plant species, namely Brillantaisia patula (BR-PA), Crossopteryx febrifuga (CR-FE) and Senna siamea (SE-SI). The obtained AgNPs were studied for their optical, structural, surface morphological and antibacterial properties. The prepared AgNPs were characterized by using UV-Visible spectra, Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray spectroscopy (EDX) and X-ray diffractometer (XRD). The synthesized nanoparticles were spherical shaped and well-dispersed with average sizes ranging from 45 to 110 nm. The AgNPs derived from BR-PA, CR-FE and SE-SI exhibited higher antibacterial activity against three bacterial pathogens of the human skin compared to their respective crude extracts and AgNO3. This indicated that the biomolecules covering the nanoparticles may enhance the biological activity of metal nanoparticles. Hence, our results support that biogenic synthesis of AgNPs from Congolese plants constitutes a potential area of interest for the therapeutic management of microbial diseases such as infectious skin diseases.
- Full Text:
- Authors: Kambale, Espoir K , Nkanga, Christian I , Mutonkole, Blaise-Pascal I , Bapolisi, Alain M , Tassa, Daniel O , Liesse, Jean-Marie I , Krause, Rui W M , Memvanga, Patrick B
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193419 , vital:45330 , xlink:href="https://doi.org/10.1016/j.heliyon.2020.e04493"
- Description: In the present study, silver nanoparticles (AgNPs) were synthesized using aqueous leaf extracts of three Congolese plant species, namely Brillantaisia patula (BR-PA), Crossopteryx febrifuga (CR-FE) and Senna siamea (SE-SI). The obtained AgNPs were studied for their optical, structural, surface morphological and antibacterial properties. The prepared AgNPs were characterized by using UV-Visible spectra, Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray spectroscopy (EDX) and X-ray diffractometer (XRD). The synthesized nanoparticles were spherical shaped and well-dispersed with average sizes ranging from 45 to 110 nm. The AgNPs derived from BR-PA, CR-FE and SE-SI exhibited higher antibacterial activity against three bacterial pathogens of the human skin compared to their respective crude extracts and AgNO3. This indicated that the biomolecules covering the nanoparticles may enhance the biological activity of metal nanoparticles. Hence, our results support that biogenic synthesis of AgNPs from Congolese plants constitutes a potential area of interest for the therapeutic management of microbial diseases such as infectious skin diseases.
- Full Text:
Ground-truthing climate-matching predictions in a post-release evaluation
- Muskett, Phillippa C, Paterson, Iain D, Coetzee, Julie A
- Authors: Muskett, Phillippa C , Paterson, Iain D , Coetzee, Julie A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423504 , vital:72067 , xlink:href="https://doi.org/10.1016/j.biocontrol.2020.104217"
- Description: Pereskia aculeata Miller (Cactaceae) is an invasive alien cactus which has negative impacts on indigenous plant biodiversity in South Africa. Catorhintha schaffneri Barilovsky and Garcia (Coreidae), the pereskia stem-wilter, was collected at coastal sites in the subtropical region of Santa Catarina state in southern Brazil and released as a biological control agent to control P. aculeata, in South Africa, in 2014. The introduced distribution of P. aculeata covers a wide variety of climatic conditions which was expected to influence the establishment success of the new agent. The thermal tolerance of C. schaffneri was investigated by developing a degree-day model and calculating the thermal limits of the species. The influence of humidity on egg hatchability and adult survival was also investigated. These data were then used to determine where the agent was likely to establish in South Africa using both weather station and microclimate temperature data. To ground-truth these predictions, sixteen release sites were selected covering a wide range of climatic conditions in the introduced distribution. Three releases of 30 adult C. schaffneri were conducted at each site and population establishment was recorded. Field establishment was recorded at only two of the sixteen experimental release sites. Low winter temperatures were predicted to prevent establishment at seven of the sixteen sites, but nine sites were considered climatically suitable according to the agent’s thermal physiology. Low rainfall and humidity could explain why the agent did not survive at some sites with suitable thermal climates. Many of the thermally suitable sites were affected by a severe drought over the course of the experiment, so further releases during periods with average rainfall and humidity are warranted and could confirm whether the drought was a significant factor influencing the failure of the agent to establish. Although climatic-matching and thermal physiology studies are valuable for tentative predictions of establishment success, there are numerous variables involved that require ground-truthing. Releasing the agent over a wide range of climatic zones believed to be within the thermal limits of the agent, and following releases with detailed post-release evaluations may be the best method of determining where future releases should be focused.
- Full Text:
- Authors: Muskett, Phillippa C , Paterson, Iain D , Coetzee, Julie A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423504 , vital:72067 , xlink:href="https://doi.org/10.1016/j.biocontrol.2020.104217"
- Description: Pereskia aculeata Miller (Cactaceae) is an invasive alien cactus which has negative impacts on indigenous plant biodiversity in South Africa. Catorhintha schaffneri Barilovsky and Garcia (Coreidae), the pereskia stem-wilter, was collected at coastal sites in the subtropical region of Santa Catarina state in southern Brazil and released as a biological control agent to control P. aculeata, in South Africa, in 2014. The introduced distribution of P. aculeata covers a wide variety of climatic conditions which was expected to influence the establishment success of the new agent. The thermal tolerance of C. schaffneri was investigated by developing a degree-day model and calculating the thermal limits of the species. The influence of humidity on egg hatchability and adult survival was also investigated. These data were then used to determine where the agent was likely to establish in South Africa using both weather station and microclimate temperature data. To ground-truth these predictions, sixteen release sites were selected covering a wide range of climatic conditions in the introduced distribution. Three releases of 30 adult C. schaffneri were conducted at each site and population establishment was recorded. Field establishment was recorded at only two of the sixteen experimental release sites. Low winter temperatures were predicted to prevent establishment at seven of the sixteen sites, but nine sites were considered climatically suitable according to the agent’s thermal physiology. Low rainfall and humidity could explain why the agent did not survive at some sites with suitable thermal climates. Many of the thermally suitable sites were affected by a severe drought over the course of the experiment, so further releases during periods with average rainfall and humidity are warranted and could confirm whether the drought was a significant factor influencing the failure of the agent to establish. Although climatic-matching and thermal physiology studies are valuable for tentative predictions of establishment success, there are numerous variables involved that require ground-truthing. Releasing the agent over a wide range of climatic zones believed to be within the thermal limits of the agent, and following releases with detailed post-release evaluations may be the best method of determining where future releases should be focused.
- Full Text:
Life after training: Professional experiences of early career clinical and counselling psychologists in South Africa
- Haine, Phillipa, Booysen, Duane D
- Authors: Haine, Phillipa , Booysen, Duane D
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450703 , vital:74975 , xlink:href="https://doi.org/10.1080/14330237.2020.1821317"
- Description: We aimed to gain an in-depth understanding of the lived professional experiences of early career clinical and counselling psychologists in South Africa. Our informants were four early career psychologists (females = 2, males = 2; clinical = 2, counselling = 2; period in service = 1 to 7 years). They completed semi-structured interviews on their critical early career professional experiences, as well as the meanings they attributed to these experiences. Interpretative phenomenological analysis of the data yielded four super-ordinate themes: (i) training as a ‘rite of passage’; (ii) expectations for a professional future; (iii) entering the professional psychology workspace; and (iv) future career directions. Findings suggest employment opportunities in the healthcare system to influence the professional socialisation of early career psychologists in addition to their personal choices. Systemic factors appear to explain why South African psychologists would opt to practice privately, and why debates on the profession’s relevance, accessibility, and credibility may continue unabated.
- Full Text:
- Authors: Haine, Phillipa , Booysen, Duane D
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450703 , vital:74975 , xlink:href="https://doi.org/10.1080/14330237.2020.1821317"
- Description: We aimed to gain an in-depth understanding of the lived professional experiences of early career clinical and counselling psychologists in South Africa. Our informants were four early career psychologists (females = 2, males = 2; clinical = 2, counselling = 2; period in service = 1 to 7 years). They completed semi-structured interviews on their critical early career professional experiences, as well as the meanings they attributed to these experiences. Interpretative phenomenological analysis of the data yielded four super-ordinate themes: (i) training as a ‘rite of passage’; (ii) expectations for a professional future; (iii) entering the professional psychology workspace; and (iv) future career directions. Findings suggest employment opportunities in the healthcare system to influence the professional socialisation of early career psychologists in addition to their personal choices. Systemic factors appear to explain why South African psychologists would opt to practice privately, and why debates on the profession’s relevance, accessibility, and credibility may continue unabated.
- Full Text:
Lions do not change rivers: complex African savannas preclude top-down forcing by large carnivores
- Comley, Jessica, Joubert, Christoffel J, Mgqatsa, Nokubonga, Parker, Daniel M
- Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/462634 , vital:76321 , xlink:href="https://doi.org/10.1016/j.jnc.2020.125844"
- Description: Trophic cascade theories such as the ‘behaviourally-mediated trophic cascade hypothesis’ (BMTCH), have mainstreamed as ecological tools for conserving biodiversity and restoring ecosystems. The BMTCH relies on indirect negative effects of large carnivores through suppression of mesocarnivore activity and habitat use. Importantly, effects of top carnivores on mesocarnivores varies over time and space, is dependent on the species involved, and local context. In South Africa, there are very few free-ranging carnivores, as populations are often restricted to enclosed reserves. While predator-proof fences reduce human-wildlife conflict, they also influence space use within communities. We used an enclosed reserve with a relatively full complement of carnivores to test the generality of the BMTCH in the African context. Using single-species, multi-season occupancy models we investigated the spatial dynamics of multiple carnivores. We also investigated spatial partitioning by vegetation type and temporal partitioning. Our results revealed both support for and against the BMTCH. Lions and spotted hyaenas negatively influenced the detection probability of black-backed jackals and African wildcats, while leopards had a positive effect on these two mesocarnivore species. Additionally, lions positively influenced the detection probability of side-striped jackals. Although space use of carnivores in relation to vegetation type showed minimal evidence of spatial partitioning, each carnivore had a unique combination of abiotic and biotic factors influencing their spatial dynamics, which could facilitate co-existence. Temporal partitioning may also be promoting co-existence as activity patterns of smaller carnivores overlapped the least with sympatric carnivores, particularly lions. Extensive activity overlap between large carnivores does not promote co-existence. We suggest that applying the BMTCH as a universal law across ecosystems is unsupported and may lead to inappropriate conservation and management actions, and prevent protection of ecosystems.
- Full Text:
- Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/462634 , vital:76321 , xlink:href="https://doi.org/10.1016/j.jnc.2020.125844"
- Description: Trophic cascade theories such as the ‘behaviourally-mediated trophic cascade hypothesis’ (BMTCH), have mainstreamed as ecological tools for conserving biodiversity and restoring ecosystems. The BMTCH relies on indirect negative effects of large carnivores through suppression of mesocarnivore activity and habitat use. Importantly, effects of top carnivores on mesocarnivores varies over time and space, is dependent on the species involved, and local context. In South Africa, there are very few free-ranging carnivores, as populations are often restricted to enclosed reserves. While predator-proof fences reduce human-wildlife conflict, they also influence space use within communities. We used an enclosed reserve with a relatively full complement of carnivores to test the generality of the BMTCH in the African context. Using single-species, multi-season occupancy models we investigated the spatial dynamics of multiple carnivores. We also investigated spatial partitioning by vegetation type and temporal partitioning. Our results revealed both support for and against the BMTCH. Lions and spotted hyaenas negatively influenced the detection probability of black-backed jackals and African wildcats, while leopards had a positive effect on these two mesocarnivore species. Additionally, lions positively influenced the detection probability of side-striped jackals. Although space use of carnivores in relation to vegetation type showed minimal evidence of spatial partitioning, each carnivore had a unique combination of abiotic and biotic factors influencing their spatial dynamics, which could facilitate co-existence. Temporal partitioning may also be promoting co-existence as activity patterns of smaller carnivores overlapped the least with sympatric carnivores, particularly lions. Extensive activity overlap between large carnivores does not promote co-existence. We suggest that applying the BMTCH as a universal law across ecosystems is unsupported and may lead to inappropriate conservation and management actions, and prevent protection of ecosystems.
- Full Text:
Nonlinear optical response and electrocatalytic activity of cobalt phthalocyanine clicked zinc oxide nanoparticles
- Mpeta, Lekhetho S, Sekhosana, Kutloano E, Nyokong, Tebello
- Authors: Mpeta, Lekhetho S , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186179 , vital:44471 , xlink:href="https://doi.org/10.1016/j.ica.2020.119661"
- Description: In this article, we report on the linking of cobalt tetrakis (4-pentyn-oxy) phthalocyanine (CoTPPc) to ZnO nanoparticles via click chemistry. Subsequently, electrocatalytic activity and nonlinear optical properties were investigated (the latter using an open Z-scan technique at 532 nm). The linking of CoTPPc with ZnO resulted in the lowest limiting intensity value of 0.27 J.Cm−2, the βeff (cmW−1) values were found to be 1.51 × 10-8 and 7.10 × 104 for ZnO and CoTPPc-ZnO respectively. The catalytic rate constants (M−1s−1) (and limits of detection) were 4.1 × 104 (12.87 µM), 5.7 × 104 (8.62 µM) and 7.36 × 104 (4.35 µM) for ZnO, CoTPPc and CoTPPc-ZnO. Hence linking ZnO nanoparticles to CoTPPc result in the enhancement of both nonlinear optical behaviour and catalytic activity.
- Full Text:
- Authors: Mpeta, Lekhetho S , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186179 , vital:44471 , xlink:href="https://doi.org/10.1016/j.ica.2020.119661"
- Description: In this article, we report on the linking of cobalt tetrakis (4-pentyn-oxy) phthalocyanine (CoTPPc) to ZnO nanoparticles via click chemistry. Subsequently, electrocatalytic activity and nonlinear optical properties were investigated (the latter using an open Z-scan technique at 532 nm). The linking of CoTPPc with ZnO resulted in the lowest limiting intensity value of 0.27 J.Cm−2, the βeff (cmW−1) values were found to be 1.51 × 10-8 and 7.10 × 104 for ZnO and CoTPPc-ZnO respectively. The catalytic rate constants (M−1s−1) (and limits of detection) were 4.1 × 104 (12.87 µM), 5.7 × 104 (8.62 µM) and 7.36 × 104 (4.35 µM) for ZnO, CoTPPc and CoTPPc-ZnO. Hence linking ZnO nanoparticles to CoTPPc result in the enhancement of both nonlinear optical behaviour and catalytic activity.
- Full Text:
Optical limiting properties of D-π-A BODIPY dyes in the presence and absence of methyl groups at the 1, 7-positions
- May, Aviwe K, Mack, John, Nyokong, Tebello
- Authors: May, Aviwe K , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186146 , vital:44468 , xlink:href="https://doi.org/10.1142/S1088424620500315"
- Description: The optical limiting properties of three meso-pentafluorophenylstyrylBODIPY dyes are investigated in the presence and absence of methyl groups at the 1,7-positions that hinder free rotation of the meso-aryl group. Pentafluorophenyl groups are introduced at the meso-position, while 4-diethylaminostyryl groups are introduced at the 3- and/or 5-positions to form dyes with strong donor-ππ-acceptor (D-ππ-A) properties to enhance the dipole moment of the molecule. Favorable optical limiting properties are obtained for all three dyes, with the highest second-order hyperpolarizability value obtained for a monostyryl dye with no methyl groups at the 1,7-position. Bromination at the 2,6-positions of a 1,7-methyl substituted dye is found to result in second-order hyperpolarizability that is an order of magnitude lower than that calculated for the analogous non-halogenated dye.
- Full Text:
- Authors: May, Aviwe K , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186146 , vital:44468 , xlink:href="https://doi.org/10.1142/S1088424620500315"
- Description: The optical limiting properties of three meso-pentafluorophenylstyrylBODIPY dyes are investigated in the presence and absence of methyl groups at the 1,7-positions that hinder free rotation of the meso-aryl group. Pentafluorophenyl groups are introduced at the meso-position, while 4-diethylaminostyryl groups are introduced at the 3- and/or 5-positions to form dyes with strong donor-ππ-acceptor (D-ππ-A) properties to enhance the dipole moment of the molecule. Favorable optical limiting properties are obtained for all three dyes, with the highest second-order hyperpolarizability value obtained for a monostyryl dye with no methyl groups at the 1,7-position. Bromination at the 2,6-positions of a 1,7-methyl substituted dye is found to result in second-order hyperpolarizability that is an order of magnitude lower than that calculated for the analogous non-halogenated dye.
- Full Text:
Plant-Based Synthesis of Silver Nanoparticles Using Aqueous Leaf Extract of Salvia officinalis: Characterization and its Antiplasmodial Activity
- Okaiyeto, Kunle, Hoppe, Heinrich C, Okoh, Anthony I
- Authors: Okaiyeto, Kunle , Hoppe, Heinrich C , Okoh, Anthony I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429472 , vital:72613 , xlink:href="https://doi.org/10.1007/s10876-020-01766-y"
- Description: In the present study, an aqueous leaf extract of Salvia officinalis was used to synthesize silver nanoparticles (AgNPs) and characterized with different techniques such as UV–vis spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDX), Transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Subsequently, its cytotoxic effect against human cervix adenocarcinoma (HeLa) cells and antiplasmodial activity against Plasmodium falciparum were investigated. UV–vis spectrum of AgNPs displayed an absorption peak at 323 nm and TEM result revealed it to be spherical in shape with average size of 41 nm. FTIR results highlighted the key bioactive compounds that could be responsible for the reduction and capping of AgNPs and XRD analysis showed its crystalline nature with a face-centered cubic (fcc) structure. The synthesized AgNPs was found to be less cytotoxic against HeLa cells line and demonstrated good antiplasmodial potential (IC50 = 3.6 µg/mL). Findings from this study indicated that the AgNPs could serve as a template in the development of new drugs for the control of malaria and hence, further study is needed to identify and characterize the potent molecules that suppress the malaria parasite.
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- Authors: Okaiyeto, Kunle , Hoppe, Heinrich C , Okoh, Anthony I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429472 , vital:72613 , xlink:href="https://doi.org/10.1007/s10876-020-01766-y"
- Description: In the present study, an aqueous leaf extract of Salvia officinalis was used to synthesize silver nanoparticles (AgNPs) and characterized with different techniques such as UV–vis spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDX), Transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Subsequently, its cytotoxic effect against human cervix adenocarcinoma (HeLa) cells and antiplasmodial activity against Plasmodium falciparum were investigated. UV–vis spectrum of AgNPs displayed an absorption peak at 323 nm and TEM result revealed it to be spherical in shape with average size of 41 nm. FTIR results highlighted the key bioactive compounds that could be responsible for the reduction and capping of AgNPs and XRD analysis showed its crystalline nature with a face-centered cubic (fcc) structure. The synthesized AgNPs was found to be less cytotoxic against HeLa cells line and demonstrated good antiplasmodial potential (IC50 = 3.6 µg/mL). Findings from this study indicated that the AgNPs could serve as a template in the development of new drugs for the control of malaria and hence, further study is needed to identify and characterize the potent molecules that suppress the malaria parasite.
- Full Text: