A wake-up call: Equity, inequality and Covid-19 emergency remote teaching and learning
- Czerniewicz, Laura, Agherdien, Najma, Badenhorst, Johan, Belluigi, Dina, Chambers, Tracey, Chili, Muntuwenkosi, De Villiers, Magriet, Felix, Alan, Gachago, Daniela, Gokhale, Craig, Ivala, Eunice, Kramm, Neil, Madiba, Matete, Mistri, Gitanjali, Mgqwashu, Emmanuel, Pallitt, Nicola, Prinsloo, Paul, Solomon, Kelly, Strydom, Sonja, Swanepoel, Mike, Waghid, Faiq, Wissing, Gerrit
- Authors: Czerniewicz, Laura , Agherdien, Najma , Badenhorst, Johan , Belluigi, Dina , Chambers, Tracey , Chili, Muntuwenkosi , De Villiers, Magriet , Felix, Alan , Gachago, Daniela , Gokhale, Craig , Ivala, Eunice , Kramm, Neil , Madiba, Matete , Mistri, Gitanjali , Mgqwashu, Emmanuel , Pallitt, Nicola , Prinsloo, Paul , Solomon, Kelly , Strydom, Sonja , Swanepoel, Mike , Waghid, Faiq , Wissing, Gerrit
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439449 , vital:73598 , https://doi.org/10.1007/s42438-020-00187-4
- Description: Produced from experiences at the outset of the intense times when Covid-19 lockdown restrictions began in March 2020, this collaborative paper offers the collective reflections and analysis of a group of teaching and learning and Higher Education (HE) scholars from a diverse 15 of the 26 South African public universities. In the form of a theorised narrative insistent on foregrounding personal voices, it presents a snapshot of the pandemic addressing the following question: what does the ‘pivot online’to Emergency Remote Teaching and Learning (ERTL), forced into urgent existence by the Covid-19 pandemic, mean for equity considerations in teaching and learning in HE? Drawing on the work of Therborn (2009: 20–32; 2012: 579–589; 2013; 2020) the reflections consider the forms of inequality-vital, resource and existential-exposed in higher education. Drawing on the work of Tronto (1993; 2015; White and Tronto 2004) the paper shows the networks of care which were formed as a counter to the systemic failures of the sector at the onset of the pandemic.
- Full Text:
- Date Issued: 2020
- Authors: Czerniewicz, Laura , Agherdien, Najma , Badenhorst, Johan , Belluigi, Dina , Chambers, Tracey , Chili, Muntuwenkosi , De Villiers, Magriet , Felix, Alan , Gachago, Daniela , Gokhale, Craig , Ivala, Eunice , Kramm, Neil , Madiba, Matete , Mistri, Gitanjali , Mgqwashu, Emmanuel , Pallitt, Nicola , Prinsloo, Paul , Solomon, Kelly , Strydom, Sonja , Swanepoel, Mike , Waghid, Faiq , Wissing, Gerrit
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439449 , vital:73598 , https://doi.org/10.1007/s42438-020-00187-4
- Description: Produced from experiences at the outset of the intense times when Covid-19 lockdown restrictions began in March 2020, this collaborative paper offers the collective reflections and analysis of a group of teaching and learning and Higher Education (HE) scholars from a diverse 15 of the 26 South African public universities. In the form of a theorised narrative insistent on foregrounding personal voices, it presents a snapshot of the pandemic addressing the following question: what does the ‘pivot online’to Emergency Remote Teaching and Learning (ERTL), forced into urgent existence by the Covid-19 pandemic, mean for equity considerations in teaching and learning in HE? Drawing on the work of Therborn (2009: 20–32; 2012: 579–589; 2013; 2020) the reflections consider the forms of inequality-vital, resource and existential-exposed in higher education. Drawing on the work of Tronto (1993; 2015; White and Tronto 2004) the paper shows the networks of care which were formed as a counter to the systemic failures of the sector at the onset of the pandemic.
- Full Text:
- Date Issued: 2020
Absent fathers: psychological and socio-economic implications for black children and directions for future research
- Magqamfana, Simnikiwe H, Bazana, Sandiso
- Authors: Magqamfana, Simnikiwe H , Bazana, Sandiso
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163443 , vital:41038 , DOI: 10.1080/14330237.2020.1744299
- Description: This study investigated fathers’ absence influences on the self-perceptions of South African young adults. Informants were five black university students (two females, three males; age range 20 to 28 years). They responded to semi-structured face-to-face interviews on self-perceptions from having matured in the absence of their biological fathers. Thematic analysis of the data revealed that the informants consider the father-absence when they grapple with material well-being shortage. Participants had mixed perceptions about the psychosocial effects on them from father-absence, with some believing to be thriving despite a history of father-absence. Overall, the findings suggest a need for caution in pathologising young adults with a history of father-absence as necessarily deprived.
- Full Text:
- Date Issued: 2020
- Authors: Magqamfana, Simnikiwe H , Bazana, Sandiso
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163443 , vital:41038 , DOI: 10.1080/14330237.2020.1744299
- Description: This study investigated fathers’ absence influences on the self-perceptions of South African young adults. Informants were five black university students (two females, three males; age range 20 to 28 years). They responded to semi-structured face-to-face interviews on self-perceptions from having matured in the absence of their biological fathers. Thematic analysis of the data revealed that the informants consider the father-absence when they grapple with material well-being shortage. Participants had mixed perceptions about the psychosocial effects on them from father-absence, with some believing to be thriving despite a history of father-absence. Overall, the findings suggest a need for caution in pathologising young adults with a history of father-absence as necessarily deprived.
- Full Text:
- Date Issued: 2020
Acceptance of ambulatory blood pressure monitoring in a semi-rural population in South Africa:
- Chiwanza, Farisai, Irwin, Yoland, Dowse, Roslind
- Authors: Chiwanza, Farisai , Irwin, Yoland , Dowse, Roslind
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157072 , vital:40084 , DOI: https://doi.org/10.4102/hsag.v25i0.1336
- Description: Ambulatory blood pressure monitoring is a valuable tool that helps in providing an insight into the diagnosis and management of hypertension; however, no evidence exists of its acceptance in the diverse South African population. We assessed the acceptance of an ambulatory blood pressure monitor in patients attending public sector primary health care (PHC) clinics. Five PHC clinics in the Makana subdistrict in the Eastern Cape.
- Full Text:
- Date Issued: 2020
- Authors: Chiwanza, Farisai , Irwin, Yoland , Dowse, Roslind
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157072 , vital:40084 , DOI: https://doi.org/10.4102/hsag.v25i0.1336
- Description: Ambulatory blood pressure monitoring is a valuable tool that helps in providing an insight into the diagnosis and management of hypertension; however, no evidence exists of its acceptance in the diverse South African population. We assessed the acceptance of an ambulatory blood pressure monitor in patients attending public sector primary health care (PHC) clinics. Five PHC clinics in the Makana subdistrict in the Eastern Cape.
- Full Text:
- Date Issued: 2020
Acetophenone substituted phthalocyanines and their graphene quantum dots conjugates as photosensitizers for photodynamic antimicrobial chemotherapy against Staphylococcus aureus
- Openda, Yolande I, Sen, Pinar, Managa, Muthumuni, Nyokong, Tebello
- Authors: Openda, Yolande I , Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186507 , vital:44506 , xlink:href="https://doi.org/10.1016/j.pdpdt.2019.101607"
- Description: This work reports on the synthesis and characterization of novel acetophenone substituted phthalocyanines along with the self-assembled nanoconjugates formed via π-π stacking interaction between the synthesized unmetalated (2), zinc (3) and indium (4) phthalocyanines and graphene quantum dots (GQDs) to form 2@GQDs, 3@GQDs and 4@GQDs. The complexes and conjugates exhibited high singlet oxygen ranging from 0.20 to 0.79 in DMSO for Pcs and nanoconjugates where in all cases, the indium complexes showed the highest singlet oxygen quantum yields. The photodynamic antimicrobial chemotherapy activity of both phthalocyanines and nanoconjugates were tested against Staphylococcus aureus. 4@GQDs was found to be highly effective causing a 9.68 log reduction of the bacteria at 10 μM (based on Pc) when compared to 3.77 log reduction of 3@GQDs.
- Full Text:
- Date Issued: 2020
- Authors: Openda, Yolande I , Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186507 , vital:44506 , xlink:href="https://doi.org/10.1016/j.pdpdt.2019.101607"
- Description: This work reports on the synthesis and characterization of novel acetophenone substituted phthalocyanines along with the self-assembled nanoconjugates formed via π-π stacking interaction between the synthesized unmetalated (2), zinc (3) and indium (4) phthalocyanines and graphene quantum dots (GQDs) to form 2@GQDs, 3@GQDs and 4@GQDs. The complexes and conjugates exhibited high singlet oxygen ranging from 0.20 to 0.79 in DMSO for Pcs and nanoconjugates where in all cases, the indium complexes showed the highest singlet oxygen quantum yields. The photodynamic antimicrobial chemotherapy activity of both phthalocyanines and nanoconjugates were tested against Staphylococcus aureus. 4@GQDs was found to be highly effective causing a 9.68 log reduction of the bacteria at 10 μM (based on Pc) when compared to 3.77 log reduction of 3@GQDs.
- Full Text:
- Date Issued: 2020
Afromelampsalta, a new genus, a new species, and five new combinations of African cicadettine cicadas (Hemiptera: Cicadidae: Cicadettinae):
- Sanborn, Allen F, Villet, Martin H
- Authors: Sanborn, Allen F , Villet, Martin H
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140680 , vital:37909
- Description: Afromelampsalta n. gen. is described for African species currently assigned to the genera Melampsalta Kolenati, 1857. Cicadetta Kolenati, 1857 and Pauropsalta Goding and Froggatt, 1904, and the new species Afromelampsalta luteofasciata n. gen., n. sp. is described. Afromelampsalta aethiopica (Distant, 1905) n. comb., A. cadisia (Walker, 1850) n. comb. and A. leucoptera (Germar, 1830) n. comb. are reassigned from Melampsalta to Afromelampsalta n. gen., A. limitata (Walker, 1852) n. comb. is transferred from Cicadetta Kolenati, 1857 and A. mimica (Distant ,1907) n. comb. is transferred from Pauropsalta Goding and Froggatt, 1904 to Afromelampsalta n. gen. Notes on the biology of the new species, a description of the exuvia of A. mimica n. comb., and a key to the species of African Cicadettini are provided.
- Full Text:
- Date Issued: 2020
- Authors: Sanborn, Allen F , Villet, Martin H
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140680 , vital:37909
- Description: Afromelampsalta n. gen. is described for African species currently assigned to the genera Melampsalta Kolenati, 1857. Cicadetta Kolenati, 1857 and Pauropsalta Goding and Froggatt, 1904, and the new species Afromelampsalta luteofasciata n. gen., n. sp. is described. Afromelampsalta aethiopica (Distant, 1905) n. comb., A. cadisia (Walker, 1850) n. comb. and A. leucoptera (Germar, 1830) n. comb. are reassigned from Melampsalta to Afromelampsalta n. gen., A. limitata (Walker, 1852) n. comb. is transferred from Cicadetta Kolenati, 1857 and A. mimica (Distant ,1907) n. comb. is transferred from Pauropsalta Goding and Froggatt, 1904 to Afromelampsalta n. gen. Notes on the biology of the new species, a description of the exuvia of A. mimica n. comb., and a key to the species of African Cicadettini are provided.
- Full Text:
- Date Issued: 2020
Agents sans frontiers: cross-border aquatic weed biological control in the rivers of southern Mozambique
- Langa, Sílvia da Fátima, Hill, Martin P, Compton, Stephen G
- Authors: Langa, Sílvia da Fátima , Hill, Martin P , Compton, Stephen G
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148998 , vital:38794 , DOI: 10.2989/16085914.2020.1749551
- Description: Biological control is an effective ways of controlling aquatic plants, especially in South Africa. Release of biological control agents has been limited to Mozambique, where water hyacinth (Eichhornia crassipes (Mart.) Solms-Laubach (Pontederiaceae)), water lettuce (Pistia stratiotes L. (Araceae)), red water ferns (Azolla spp. (Azollaceae)) and salvinia (Salvinia molesta DS Mitch. (Salviniaceae)) are significant weeds in the south of the country. In 2009, we assessed the status of these weeds in seven rivers across southern Mozambique and recorded whether any biocontrol agents were present.
- Full Text:
- Date Issued: 2020
- Authors: Langa, Sílvia da Fátima , Hill, Martin P , Compton, Stephen G
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148998 , vital:38794 , DOI: 10.2989/16085914.2020.1749551
- Description: Biological control is an effective ways of controlling aquatic plants, especially in South Africa. Release of biological control agents has been limited to Mozambique, where water hyacinth (Eichhornia crassipes (Mart.) Solms-Laubach (Pontederiaceae)), water lettuce (Pistia stratiotes L. (Araceae)), red water ferns (Azolla spp. (Azollaceae)) and salvinia (Salvinia molesta DS Mitch. (Salviniaceae)) are significant weeds in the south of the country. In 2009, we assessed the status of these weeds in seven rivers across southern Mozambique and recorded whether any biocontrol agents were present.
- Full Text:
- Date Issued: 2020
Alignment in the orientation of LOFAR radio sources:
- Osinga, E, Miley, G K, van Weeren, R J, Shimwell, T W, Duncan, K J, Hardcastle, M J, Mechev, A P, Röttgering, H J A, Tasse, C, Williams, W L
- Authors: Osinga, E , Miley, G K , van Weeren, R J , Shimwell, T W , Duncan, K J , Hardcastle, M J , Mechev, A P , Röttgering, H J A , Tasse, C , Williams, W L
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163452 , vital:41039 , https://doi.org/10.1051/0004-6361/202037680
- Description: Various studies have laid claim to finding an alignment of the polarization vectors or radio jets of active galactic nuclei over large distances, but these results have proven controversial and so far, there is no clear explanation for this observed alignment. To investigate this case further, we tested the hypothesis that the position angles of radio galaxies are randomly oriented in the sky by using data from the Low-Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS). A sample of 7555 double-lobed radio galaxies was extracted from the list of 318 520 radio sources in the first data release of LoTSS at 150 MHz. We performed statistical tests for uniformity of the two-dimensional (2D) orientations for the complete 7555 source sample. We also tested the orientation uniformity in three dimensions (3D) for the 4212 source sub-sample with photometric or spectroscopic redshifts.
- Full Text:
- Date Issued: 2020
- Authors: Osinga, E , Miley, G K , van Weeren, R J , Shimwell, T W , Duncan, K J , Hardcastle, M J , Mechev, A P , Röttgering, H J A , Tasse, C , Williams, W L
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163452 , vital:41039 , https://doi.org/10.1051/0004-6361/202037680
- Description: Various studies have laid claim to finding an alignment of the polarization vectors or radio jets of active galactic nuclei over large distances, but these results have proven controversial and so far, there is no clear explanation for this observed alignment. To investigate this case further, we tested the hypothesis that the position angles of radio galaxies are randomly oriented in the sky by using data from the Low-Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS). A sample of 7555 double-lobed radio galaxies was extracted from the list of 318 520 radio sources in the first data release of LoTSS at 150 MHz. We performed statistical tests for uniformity of the two-dimensional (2D) orientations for the complete 7555 source sample. We also tested the orientation uniformity in three dimensions (3D) for the 4212 source sub-sample with photometric or spectroscopic redshifts.
- Full Text:
- Date Issued: 2020
AMBER force field parameters for the Zn (II) ions of the tunneling-fold enzymes GTP cyclohydrolase I and 6-pyruvoyl tetrahydropterin synthase
- Khairallah, Afrah, Tastan Bishop, Ozlem, Moses, Vuyani
- Authors: Khairallah, Afrah , Tastan Bishop, Ozlem , Moses, Vuyani
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429360 , vital:72604 , xlink:href="https://doi.org/10.1080/07391102.2020.1796800"
- Description: The folate biosynthesis pathway is an essential pathway for cell growth and survival. Folate derivatives serve as a source of the one-carbon units in several intracellular metabolic reactions. Rapidly dividing cells rely heavily on the availability of folate derivatives for their proliferation. As a result, drugs targeting this pathway have shown to be effective against tumor cells and pathogens, but drug resistance against the available antifolate drugs emerged quickly. Therefore, there is a need to develop new treatment strategies and identify alternative metabolic targets. The two de novo folate biosynthesis pathway enzymes, GTP cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS), can provide an alternative strategy to overcome the drug resistance that emerged in the two primary targeted enzymes dihydrofolate reductase and dihydropteroate synthase. Both GCH1 and PTPS enzymes contain Zn2+ ions in their active sites, and to accurately study their dynamic behaviors using all-atom molecular dynamics (MD) simulations, appropriate parameters that can describe their metal sites should be developed and validated. In this study, force field parameters of the GCH1 and PTPS metal centers were generated using quantum mechanics (QM) calculations and then validated through MD simulations to ensure their accuracy in describing and maintaining the Zn2+ ion coordination environment. The derived force field parameters will provide accurate and reliable MD simulations involving these two enzymes for future in-silico identification of drug candidates against the GCH1 and PTPS enzymes.
- Full Text:
- Date Issued: 2020
- Authors: Khairallah, Afrah , Tastan Bishop, Ozlem , Moses, Vuyani
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429360 , vital:72604 , xlink:href="https://doi.org/10.1080/07391102.2020.1796800"
- Description: The folate biosynthesis pathway is an essential pathway for cell growth and survival. Folate derivatives serve as a source of the one-carbon units in several intracellular metabolic reactions. Rapidly dividing cells rely heavily on the availability of folate derivatives for their proliferation. As a result, drugs targeting this pathway have shown to be effective against tumor cells and pathogens, but drug resistance against the available antifolate drugs emerged quickly. Therefore, there is a need to develop new treatment strategies and identify alternative metabolic targets. The two de novo folate biosynthesis pathway enzymes, GTP cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS), can provide an alternative strategy to overcome the drug resistance that emerged in the two primary targeted enzymes dihydrofolate reductase and dihydropteroate synthase. Both GCH1 and PTPS enzymes contain Zn2+ ions in their active sites, and to accurately study their dynamic behaviors using all-atom molecular dynamics (MD) simulations, appropriate parameters that can describe their metal sites should be developed and validated. In this study, force field parameters of the GCH1 and PTPS metal centers were generated using quantum mechanics (QM) calculations and then validated through MD simulations to ensure their accuracy in describing and maintaining the Zn2+ ion coordination environment. The derived force field parameters will provide accurate and reliable MD simulations involving these two enzymes for future in-silico identification of drug candidates against the GCH1 and PTPS enzymes.
- Full Text:
- Date Issued: 2020
AMBER force field parameters for the Zn (II) ions of the tunneling-fold enzymes GTP cyclohydrolase I and 6-pyruvoyl tetrahydropterin synthase:
- Khairallah, Afrah, Tastan Bishop, Özlem, Moses, Vuyani
- Authors: Khairallah, Afrah , Tastan Bishop, Özlem , Moses, Vuyani
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163068 , vital:41009 , DOI: 10.1080/07391102.2020.1796800
- Description: The folate biosynthesis pathway is an essential pathway for cell growth and survival. Folate derivatives serve as a source of the one-carbon units in several intracellular metabolic reactions. Rapidly dividing cells rely heavily on the availability of folate derivatives for their proliferation. As a result, drugs targeting this pathway have shown to be effective against tumor cells and pathogens, but drug resistance against the available antifolate drugs emerged quickly. Therefore, there is a need to develop new treatment strategies and identify alternative metabolic targets. The two de novo folate biosynthesis pathway enzymes, GTP cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS), can provide an alternative strategy to overcome the drug resistance that emerged in the two primary targeted enzymes dihydrofolate reductase and dihydropteroate synthase.
- Full Text:
- Date Issued: 2020
- Authors: Khairallah, Afrah , Tastan Bishop, Özlem , Moses, Vuyani
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163068 , vital:41009 , DOI: 10.1080/07391102.2020.1796800
- Description: The folate biosynthesis pathway is an essential pathway for cell growth and survival. Folate derivatives serve as a source of the one-carbon units in several intracellular metabolic reactions. Rapidly dividing cells rely heavily on the availability of folate derivatives for their proliferation. As a result, drugs targeting this pathway have shown to be effective against tumor cells and pathogens, but drug resistance against the available antifolate drugs emerged quickly. Therefore, there is a need to develop new treatment strategies and identify alternative metabolic targets. The two de novo folate biosynthesis pathway enzymes, GTP cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS), can provide an alternative strategy to overcome the drug resistance that emerged in the two primary targeted enzymes dihydrofolate reductase and dihydropteroate synthase.
- Full Text:
- Date Issued: 2020
An effort to study the influence of tides on the longitudinal variation of vertical E× B drift over the African sector:
- Habyarimana, Valence, Habarulema, John B, Mungufeni, Patrick, Uwamahoro, Jean C
- Authors: Habyarimana, Valence , Habarulema, John B , Mungufeni, Patrick , Uwamahoro, Jean C
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149026 , vital:38797 , https://doi.org/10.1016/j.jastp.2020.105338
- Description: Meteorological processes such as tides influence ionospheric variability through vertical coupling. For the first time, we have used data from Communication Navigation Outage and Forecasting System (C/NOFS) satellite from 2008–2015 to develop a Neural Network (NN) vertical E×B drift model over the African region, with inclusion of a proxy of tides as one of the inputs together with other physical and geophysical inputs. Two models (with and without tidal proxy input) were developed for both East and West African sectors. To derive the tidal proxy, we first calculate the 60-day running means per year which were subtracted from the actual vertical E×B drift measurements to obtain a set of residuals. The purpose of the subtraction was to remove long-term trends in vertical E×B drift that could potentially alias into tides.
- Full Text:
- Date Issued: 2020
- Authors: Habyarimana, Valence , Habarulema, John B , Mungufeni, Patrick , Uwamahoro, Jean C
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149026 , vital:38797 , https://doi.org/10.1016/j.jastp.2020.105338
- Description: Meteorological processes such as tides influence ionospheric variability through vertical coupling. For the first time, we have used data from Communication Navigation Outage and Forecasting System (C/NOFS) satellite from 2008–2015 to develop a Neural Network (NN) vertical E×B drift model over the African region, with inclusion of a proxy of tides as one of the inputs together with other physical and geophysical inputs. Two models (with and without tidal proxy input) were developed for both East and West African sectors. To derive the tidal proxy, we first calculate the 60-day running means per year which were subtracted from the actual vertical E×B drift measurements to obtain a set of residuals. The purpose of the subtraction was to remove long-term trends in vertical E×B drift that could potentially alias into tides.
- Full Text:
- Date Issued: 2020
An improved systems approach as a phytosanitary measure for Thaumatotibia leucotreta (Lepidoptera: Tortricidae) in export citrus fruit from South Africa
- Hattingh, Vaughan, Moore, Sean D, Kirkman, Wayne, Goddard, Mat, Thackeray, Sean, Peyper, Mellissa, Sharp, Gary, Cronjé, Paul, Pringle, Ken
- Authors: Hattingh, Vaughan , Moore, Sean D , Kirkman, Wayne , Goddard, Mat , Thackeray, Sean , Peyper, Mellissa , Sharp, Gary , Cronjé, Paul , Pringle, Ken
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423700 , vital:72086 , xlink:href="https://doi.org/10.1093/jee/toz336"
- Description: A systems approach was previously developed for mitigating phytosanitary risk of Thaumatotibia leucotreta (Meyrick) in citrus fruit exported from South Africa, as an alternative to a standalone cold disinfestation treatment. The present study first tested the original systems approach by applying it on a semicommercial scale in 10 Nova mandarin orchards. Fruit were inspected at points in the production, packing, and simulated shipping process, to assess performance of the systems approach. Additional data were obtained from 17 Valencia orange orchards and six packinghouses. In the second part of this study, the systems approach was accordingly revised and improved, consisting of three measures: 1) preharvest controls and measurements and postpicking sampling, inspection, and packinghouse procedures; 2) postpacking sampling and inspection; and 3) shipping conditions. The model quantifying the effectiveness of the systems approach was improved by correcting errors in the original version, updating parameter values and adding a component that provides for comparison with the risk mitigation provided by a standalone disinfestation treatment. Consequently, the maximum potential proportion of fruit that may be infested with live T. leucotreta after application of the improved systems approach is no greater than the proportion of fruit that may be infested after application of a Probit 9 efficacy postharvest disinfestation treatment to fruit with a 2% pretreatment infestation. The probability of a mating pair surviving is also determined. The model enables a priori determination of the required threshold levels for any of the three measures, based on quantification of the other two measures.
- Full Text:
- Date Issued: 2020
- Authors: Hattingh, Vaughan , Moore, Sean D , Kirkman, Wayne , Goddard, Mat , Thackeray, Sean , Peyper, Mellissa , Sharp, Gary , Cronjé, Paul , Pringle, Ken
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423700 , vital:72086 , xlink:href="https://doi.org/10.1093/jee/toz336"
- Description: A systems approach was previously developed for mitigating phytosanitary risk of Thaumatotibia leucotreta (Meyrick) in citrus fruit exported from South Africa, as an alternative to a standalone cold disinfestation treatment. The present study first tested the original systems approach by applying it on a semicommercial scale in 10 Nova mandarin orchards. Fruit were inspected at points in the production, packing, and simulated shipping process, to assess performance of the systems approach. Additional data were obtained from 17 Valencia orange orchards and six packinghouses. In the second part of this study, the systems approach was accordingly revised and improved, consisting of three measures: 1) preharvest controls and measurements and postpicking sampling, inspection, and packinghouse procedures; 2) postpacking sampling and inspection; and 3) shipping conditions. The model quantifying the effectiveness of the systems approach was improved by correcting errors in the original version, updating parameter values and adding a component that provides for comparison with the risk mitigation provided by a standalone disinfestation treatment. Consequently, the maximum potential proportion of fruit that may be infested with live T. leucotreta after application of the improved systems approach is no greater than the proportion of fruit that may be infested after application of a Probit 9 efficacy postharvest disinfestation treatment to fruit with a 2% pretreatment infestation. The probability of a mating pair surviving is also determined. The model enables a priori determination of the required threshold levels for any of the three measures, based on quantification of the other two measures.
- Full Text:
- Date Issued: 2020
An integrated analytical framework for analysing expansive learning in improved cook stove practice:
- Jalasi, Experencia Madalitso
- Authors: Jalasi, Experencia Madalitso
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149043 , vital:38798 , https://doi.org/10.1016/j.lcsi.2020.100414
- Description: This paper reveals relationships between four analytical frameworks, boundary interaction, reflexivity, transformative agency, and Sannino's reformulated Vygotskian double stimulation model in an Integrated Analytical Framework (IAF) used to analyse expansive learning processes via Boundary Crossing Change Laboratory Workshops in the development of will and volitional actions. I show how transformation emerges from expansive learning processes using two Transformative Pathways in Improved Cook Stove (ICS) practice in Chapita Village case study in Malawi. Introduction of ICSs in the traditional cooking practice generated conflict of motives within subjects of interacting activity systems. I used Cultural Historical Activity Theory (CHAT) to identify and analyse the conflict of motives using socio-cultural historical analysis and analysis of contradictions around learning, promotion, and utilisation of the ICS.
- Full Text:
- Date Issued: 2020
An integrated analytical framework for analysing expansive learning in improved cook stove practice:
- Authors: Jalasi, Experencia Madalitso
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149043 , vital:38798 , https://doi.org/10.1016/j.lcsi.2020.100414
- Description: This paper reveals relationships between four analytical frameworks, boundary interaction, reflexivity, transformative agency, and Sannino's reformulated Vygotskian double stimulation model in an Integrated Analytical Framework (IAF) used to analyse expansive learning processes via Boundary Crossing Change Laboratory Workshops in the development of will and volitional actions. I show how transformation emerges from expansive learning processes using two Transformative Pathways in Improved Cook Stove (ICS) practice in Chapita Village case study in Malawi. Introduction of ICSs in the traditional cooking practice generated conflict of motives within subjects of interacting activity systems. I used Cultural Historical Activity Theory (CHAT) to identify and analyse the conflict of motives using socio-cultural historical analysis and analysis of contradictions around learning, promotion, and utilisation of the ICS.
- Full Text:
- Date Issued: 2020
An octabrominated Sn (iv) tetraisopropylporphyrin as a photosensitizer dye for singlet oxygen biomedical applications
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186679 , vital:44524 , xlink:href="https://doi.org/10.1039/D0DT01915A"
- Description: Two novel Sn(IV) tetraisopropylphenylporphyrins have been synthesized to explore the effect of octabromination at the β-pyrrole positions on their photophysical properties and photodynamic activity. The lower energy Q band of an octabrominated complex lies at 675 nm well within the therapeutic window. The octabrominated dye has a relatively high singlet oxygen quantum yield of 0.78 in DMF and exhibits favorable photodynamic activity against MCF-7 cells with an IC50 value of 10.7 μM and a 5.74 log reduction value (5 μM) towards S. aureus under illumination at 660 nm for 60 min with a Thorlabs M660L3 LED (280 mW cm−2).
- Full Text:
- Date Issued: 2020
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186679 , vital:44524 , xlink:href="https://doi.org/10.1039/D0DT01915A"
- Description: Two novel Sn(IV) tetraisopropylphenylporphyrins have been synthesized to explore the effect of octabromination at the β-pyrrole positions on their photophysical properties and photodynamic activity. The lower energy Q band of an octabrominated complex lies at 675 nm well within the therapeutic window. The octabrominated dye has a relatively high singlet oxygen quantum yield of 0.78 in DMF and exhibits favorable photodynamic activity against MCF-7 cells with an IC50 value of 10.7 μM and a 5.74 log reduction value (5 μM) towards S. aureus under illumination at 660 nm for 60 min with a Thorlabs M660L3 LED (280 mW cm−2).
- Full Text:
- Date Issued: 2020
An update on the indigenous vascular flora of sub-Antarctic Marion Island: taxonomic changes, sequences for DNA barcode loci, and genome size data
- Chau, John H, Mtsi, Nasipi I S, Münbergová, Zuzana, Greve, Michelle, le Roux, Peter C, Mairal, Mario, Le Roux, Johannes J, Dorrington, Rosemary A, van Vuuren, Bettine
- Authors: Chau, John H , Mtsi, Nasipi I S , Münbergová, Zuzana , Greve, Michelle , le Roux, Peter C , Mairal, Mario , Le Roux, Johannes J , Dorrington, Rosemary A , van Vuuren, Bettine
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160344 , vital:40437 , https://0-doi.org.wam.seals.ac.za/10.1007/s00300-020-02747-7
- Description: The flora of sub-Antarctic Marion Island forms part of the unique South Indian Ocean Biogeographic Province, and is under threat from climate change and invasive species. Current information on the flora is necessary to rapidly identify and manage future changes. We conducted a literature search on the taxonomy of indigenous vascular plant species on Marion Island and found nomenclatural changes following taxonomic revisions for Austroblechnum penna-marina (Poir.) Gasper and V.A.O.Dittrich, Carex dikei (Nelmes) K.L.Wilson, Leptinella plumosa Hook.f., Notogrammitis crassior (Kirk) Parris, Phlegmariurus saururus (Lam.) B.Øllg., and Polypogon magellanicus (Lam.) Finot. Additionally, Ranunculus moseleyi Hook.f. was removed from our species checklist due to its long absence in floristic surveys, leaving 21 species in the indigenous vascular plant flora present on Marion Island. We also amplified and sequenced the universal plant barcoding loci rbcL and matK for 19 and 13 species, respectively, and found that ample interspecific genetic distance and minimal intraspecific genetic distance allowed for easy discrimination between species.
- Full Text:
- Date Issued: 2020
- Authors: Chau, John H , Mtsi, Nasipi I S , Münbergová, Zuzana , Greve, Michelle , le Roux, Peter C , Mairal, Mario , Le Roux, Johannes J , Dorrington, Rosemary A , van Vuuren, Bettine
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160344 , vital:40437 , https://0-doi.org.wam.seals.ac.za/10.1007/s00300-020-02747-7
- Description: The flora of sub-Antarctic Marion Island forms part of the unique South Indian Ocean Biogeographic Province, and is under threat from climate change and invasive species. Current information on the flora is necessary to rapidly identify and manage future changes. We conducted a literature search on the taxonomy of indigenous vascular plant species on Marion Island and found nomenclatural changes following taxonomic revisions for Austroblechnum penna-marina (Poir.) Gasper and V.A.O.Dittrich, Carex dikei (Nelmes) K.L.Wilson, Leptinella plumosa Hook.f., Notogrammitis crassior (Kirk) Parris, Phlegmariurus saururus (Lam.) B.Øllg., and Polypogon magellanicus (Lam.) Finot. Additionally, Ranunculus moseleyi Hook.f. was removed from our species checklist due to its long absence in floristic surveys, leaving 21 species in the indigenous vascular plant flora present on Marion Island. We also amplified and sequenced the universal plant barcoding loci rbcL and matK for 19 and 13 species, respectively, and found that ample interspecific genetic distance and minimal intraspecific genetic distance allowed for easy discrimination between species.
- Full Text:
- Date Issued: 2020
Analytical Detection and Electrocatalysis of Paracetamol in Aqueous Media Using Rare‐Earth Double‐Decker Phthalocyaninato Chelates as Electrochemically Active Materials
- Sekhosana, Kutloana E, Nkhahle, Reitumetse, Nyokong, Tebello
- Authors: Sekhosana, Kutloana 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:
- Date Issued: 2020
- Authors: Sekhosana, Kutloana 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:
- Date Issued: 2020
Anti-cancer and anti-trypanosomal properties of alkaloids from the root bark of Zanthoxylum leprieurii Guill and Perr
- Eze, Fabian I, Siwe-Noundou, Xavier, Isaacs, Michelle, Patala, Srivinas, Osadebe, Patience O, Krause, Rui W M
- Authors: Eze, Fabian I , Siwe-Noundou, Xavier , Isaacs, Michelle , Patala, Srivinas , Osadebe, Patience O , Krause, Rui W M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193352 , vital:45324 , xlink:href="http://dx.doi.org/10.4314/tjpr.v19i11.19"
- Description: Purpose: To isolate the anti-cancer and anti-trypanosomal principles of Zanthoxylum leprieurii, a medicinally versatile wild tropical plant used for managing tumours, African trypanosomiasis, and inflammation in southeastern Nigeria. Methods: The pure compounds were isolated using chromatographic methods. The structural elucidation of the pure compounds was based on their NMR (1D and 2D) and mass spectral data as well as chemical test results. Structure-activity relationships were based on the structural differences among the compounds. The cytotoxicity of the extracts and compounds (1, 2, 3, and 4) was evaluated in HeLa (human cervix adenocarcinoma) cell line while the trypanocidal activities were evaluated on Trypanosoma brucei brucei. Results: Two acridone alkaloids, 1-hydroxy-3-methoxy-10-methylacridin-9 (10H)-one, named fabiocinine (1), and 1-hydroxy-2,3-dimethoxy-10-methylacridin-9 (10H)-one (arborinine, 2), together with a furoquinoline alkaloid, skimmianine (3), and a chelerythrine derivative, 6-acetonyl-5,6-dihydrochelerythrine (4) were isolated from the root bark of Zanthoxylum leprieurii. Skimmianine (3) exhibited cytotoxicity and anti-trypanosomal IC50 of 12.8 and 13.2 µg/mL respectively (p less than 0.05). Compound (1) and arborinine (2) were selectively cytotoxic to HeLa cells with cytotoxicity IC50 of 28.49 and 62.71 µg/mL, respectively, while (4) did not show significant activity (p less than 0.05). Conclusion: Zanthoxylum leprieurii root bark contains cytotoxic and trypanocidal compounds, and is thus a potential source of anti-cancer and anti-trypanosomal leads.
- Full Text:
- Date Issued: 2020
- Authors: Eze, Fabian I , Siwe-Noundou, Xavier , Isaacs, Michelle , Patala, Srivinas , Osadebe, Patience O , Krause, Rui W M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193352 , vital:45324 , xlink:href="http://dx.doi.org/10.4314/tjpr.v19i11.19"
- Description: Purpose: To isolate the anti-cancer and anti-trypanosomal principles of Zanthoxylum leprieurii, a medicinally versatile wild tropical plant used for managing tumours, African trypanosomiasis, and inflammation in southeastern Nigeria. Methods: The pure compounds were isolated using chromatographic methods. The structural elucidation of the pure compounds was based on their NMR (1D and 2D) and mass spectral data as well as chemical test results. Structure-activity relationships were based on the structural differences among the compounds. The cytotoxicity of the extracts and compounds (1, 2, 3, and 4) was evaluated in HeLa (human cervix adenocarcinoma) cell line while the trypanocidal activities were evaluated on Trypanosoma brucei brucei. Results: Two acridone alkaloids, 1-hydroxy-3-methoxy-10-methylacridin-9 (10H)-one, named fabiocinine (1), and 1-hydroxy-2,3-dimethoxy-10-methylacridin-9 (10H)-one (arborinine, 2), together with a furoquinoline alkaloid, skimmianine (3), and a chelerythrine derivative, 6-acetonyl-5,6-dihydrochelerythrine (4) were isolated from the root bark of Zanthoxylum leprieurii. Skimmianine (3) exhibited cytotoxicity and anti-trypanosomal IC50 of 12.8 and 13.2 µg/mL respectively (p less than 0.05). Compound (1) and arborinine (2) were selectively cytotoxic to HeLa cells with cytotoxicity IC50 of 28.49 and 62.71 µg/mL, respectively, while (4) did not show significant activity (p less than 0.05). Conclusion: Zanthoxylum leprieurii root bark contains cytotoxic and trypanocidal compounds, and is thus a potential source of anti-cancer and anti-trypanosomal leads.
- Full Text:
- Date Issued: 2020
Antiparasitic Constituents of Beilschmiedia louisii and Beilschmiedia obscura and Some Semisynthetic Derivatives
- Waleguele, Christine C, Mba'ning, Brice M, Awantu, Angelbert F, Bankeu, Jean J, Fongang, Yannick S F, Ngouela, Augustin S, Tsamo, Etienne, Sewald, Norbert, Lenta, Bruno N, Krause, Rui W M
- Authors: Waleguele, Christine C , Mba'ning, Brice M , Awantu, Angelbert F , Bankeu, Jean J , Fongang, Yannick S F , Ngouela, Augustin S , Tsamo, Etienne , Sewald, Norbert , Lenta, Bruno N , Krause, Rui W M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193364 , vital:45325 , xlink:href="https://doi.org/10.3390/molecules25122862"
- Description: The MeOH/CH2Cl2 (1:1) extracts of the roots and leaves of Beilschmiedia louisii and B. obscura showed potent antitrypanosomal activity during preliminary screening on Trypanosoma brucei brucei. Phytochemical investigation of these extracts led to the isolation of a mixture of two new endiandric acid derivatives beilschmiedol B (1) and beilschmiedol C (2), and one new phenylalkene obscurene A (3) together with twelve known compounds (4–15). In addition, four new derivatives (11a–11d) were synthesized from compound 11. Their structures were elucidated based on their NMR and MS data. Compounds 5, 6, and 7 were isolated for the first time from the Beilschmiedia genus. Additionally, the NMR data of compound 4 are given here for the first time. The isolates were evaluated for their antitrypanosomal and antimalarial activities against Tb brucei and the Plasmodium falciparum chloroquine-resistant strain Pf3D7 in vitro, respectively. From the tested compounds, the mixture of new compounds 1 and 2 exhibited the most potent antitrypanosomal activity in vitro with IC50 value of 4.91 μM.
- Full Text:
- Date Issued: 2020
- Authors: Waleguele, Christine C , Mba'ning, Brice M , Awantu, Angelbert F , Bankeu, Jean J , Fongang, Yannick S F , Ngouela, Augustin S , Tsamo, Etienne , Sewald, Norbert , Lenta, Bruno N , Krause, Rui W M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193364 , vital:45325 , xlink:href="https://doi.org/10.3390/molecules25122862"
- Description: The MeOH/CH2Cl2 (1:1) extracts of the roots and leaves of Beilschmiedia louisii and B. obscura showed potent antitrypanosomal activity during preliminary screening on Trypanosoma brucei brucei. Phytochemical investigation of these extracts led to the isolation of a mixture of two new endiandric acid derivatives beilschmiedol B (1) and beilschmiedol C (2), and one new phenylalkene obscurene A (3) together with twelve known compounds (4–15). In addition, four new derivatives (11a–11d) were synthesized from compound 11. Their structures were elucidated based on their NMR and MS data. Compounds 5, 6, and 7 were isolated for the first time from the Beilschmiedia genus. Additionally, the NMR data of compound 4 are given here for the first time. The isolates were evaluated for their antitrypanosomal and antimalarial activities against Tb brucei and the Plasmodium falciparum chloroquine-resistant strain Pf3D7 in vitro, respectively. From the tested compounds, the mixture of new compounds 1 and 2 exhibited the most potent antitrypanosomal activity in vitro with IC50 value of 4.91 μM.
- Full Text:
- Date Issued: 2020
Application of quality by design principles for optimizing process variables of Extrusion and Spheronization of a Captopril Pellet Formulation:
- Veerubhotla, Krishna, Walker, Roderick B
- Authors: Veerubhotla, Krishna , Walker, Roderick B
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/178312 , vital:40098 , DOI: 10.36468/pharmaceutical-sciences.624
- Description: Product development using quality by design is a proactive and risk-based approach that shifts the manufacturing process from empirical to science-based. Risk assessment was performed to identify and analyse risk areas for the manufacture of captopril pellets. Twelve experimental runs were performed using a Plackett-Burman screening design. Pareto plots revealed the effect of formulation and process variables on the responses monitored and facilitated the identification of the most critical parameters for optimization of the formulation. A response surface methodology approach in conjunction with a central composite design was used to optimize the Eudragit® RL 30D (15-30 ml), microcrystalline cellulose (20-40 % w/w), sodium starch glycolate (2-5 % w/w) and spheronizer speed (650-1050 rpm).
- Full Text:
- Date Issued: 2020
- Authors: Veerubhotla, Krishna , Walker, Roderick B
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/178312 , vital:40098 , DOI: 10.36468/pharmaceutical-sciences.624
- Description: Product development using quality by design is a proactive and risk-based approach that shifts the manufacturing process from empirical to science-based. Risk assessment was performed to identify and analyse risk areas for the manufacture of captopril pellets. Twelve experimental runs were performed using a Plackett-Burman screening design. Pareto plots revealed the effect of formulation and process variables on the responses monitored and facilitated the identification of the most critical parameters for optimization of the formulation. A response surface methodology approach in conjunction with a central composite design was used to optimize the Eudragit® RL 30D (15-30 ml), microcrystalline cellulose (20-40 % w/w), sodium starch glycolate (2-5 % w/w) and spheronizer speed (650-1050 rpm).
- Full Text:
- Date Issued: 2020
Assessment of taste masking of captopril by ion-exchange resins using electronic gustatory system
- Chikukwa, Mellisa T, Wesoly, Malgorzata, Korzeniowska, Aleksandra B, Ciosek-Skibinska, Patrycja, Walker, Roderick B, Khamanga, Sandile M M
- Authors: Chikukwa, Mellisa T , 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:
- Date Issued: 2020
- Authors: Chikukwa, Mellisa T , 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:
- Date Issued: 2020
Attitudinal difference surveys perpetuate harmful tropes: A comment on Nattrass
- Rosenberg, Eureta, Le Grange, Lesley
- Authors: Rosenberg, Eureta , Le Grange, Lesley
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370129 , vital:66300 , xlink:href="https://doi.org/10.17159/sajs.2020/8469"
- Description: We reply to the article, ‘Why are black South African students less likely to consider studying biological sciences?’, authored by University of Cape Town (UCT) researcher Nicoli Nattrass1 and published in the South African Journal of Science on 27 May 2020. At the time of writing our reply the article had already received sharp criticism from the Black Academic Caucus at UCT and in a statement released on 5 June 2020, the UCT executive distanced itself from the content of the paper, inviting rigorous, respectful review of the published research. Nattrass’ article1 follows two papers published in 2019 by scholars associated with South African universities, both of which were widely denounced for the racist undertones of their content. The first article was authored by Stellenbosch University researchers who reported on low cognitive functioning of coloured women linked to education levels and lifestyles2 ; see comment by Le Grange3 . The second article was co-authored by an adjunct professor at UCT and examined the role of cognitive ability or intelligence on slave exports from Africa4 . These publications gave rise to a broader debate on enduring racism in science and the re-ascendency of race science internationally. In this reply, we focus on the methodology of attitudinal survey used for the study reported by Nattrass (and by many other scientists). There are two lines of argument that we weave together: the quality of the research as reported, and problems inherent to comparative attitudinal survey research (regardless of how well it is executed). It should be noted that the Black Academic Caucus at UCT has also critiqued the research design, identifying many of the points we make here, and they have additionally included a discourse analysis of the paper (circulated via e-mail). To demonstrate how problematic a survey design can be, particularly when it is not rigorously executed, we share data and observations that counter the apparent findings of Nattrass’ study. We then argue that the publication of this research, in this manner, is detrimental to the biodiversity sector in which the tropes being perpetuated, can cause enormous harm. In the process we hope to encourage scientists to be more reflexive about their methodology, and we encourage the South African Journal of Science to publish works that are worthy of the young people of this country - research in which they can recognise themselves, rather than being forced to look at reductionist portrayals, legitimised under the banner of science.
- Full Text:
- Date Issued: 2020
- Authors: Rosenberg, Eureta , Le Grange, Lesley
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370129 , vital:66300 , xlink:href="https://doi.org/10.17159/sajs.2020/8469"
- Description: We reply to the article, ‘Why are black South African students less likely to consider studying biological sciences?’, authored by University of Cape Town (UCT) researcher Nicoli Nattrass1 and published in the South African Journal of Science on 27 May 2020. At the time of writing our reply the article had already received sharp criticism from the Black Academic Caucus at UCT and in a statement released on 5 June 2020, the UCT executive distanced itself from the content of the paper, inviting rigorous, respectful review of the published research. Nattrass’ article1 follows two papers published in 2019 by scholars associated with South African universities, both of which were widely denounced for the racist undertones of their content. The first article was authored by Stellenbosch University researchers who reported on low cognitive functioning of coloured women linked to education levels and lifestyles2 ; see comment by Le Grange3 . The second article was co-authored by an adjunct professor at UCT and examined the role of cognitive ability or intelligence on slave exports from Africa4 . These publications gave rise to a broader debate on enduring racism in science and the re-ascendency of race science internationally. In this reply, we focus on the methodology of attitudinal survey used for the study reported by Nattrass (and by many other scientists). There are two lines of argument that we weave together: the quality of the research as reported, and problems inherent to comparative attitudinal survey research (regardless of how well it is executed). It should be noted that the Black Academic Caucus at UCT has also critiqued the research design, identifying many of the points we make here, and they have additionally included a discourse analysis of the paper (circulated via e-mail). To demonstrate how problematic a survey design can be, particularly when it is not rigorously executed, we share data and observations that counter the apparent findings of Nattrass’ study. We then argue that the publication of this research, in this manner, is detrimental to the biodiversity sector in which the tropes being perpetuated, can cause enormous harm. In the process we hope to encourage scientists to be more reflexive about their methodology, and we encourage the South African Journal of Science to publish works that are worthy of the young people of this country - research in which they can recognise themselves, rather than being forced to look at reductionist portrayals, legitimised under the banner of science.
- Full Text:
- Date Issued: 2020