Enhanced Solar Efficiency via Incorporation of Plasmonic Gold Nanostructures in a Titanium Oxide/Eosin Y Dye-Sensitized Solar Cell
- Nyembe, Sanele, Chindeka, Francis, Ndlovu, Gebhu, Mkhohlakali, Andile, Nyokong, Tebello, Sikhwiyhilu, Lucy
- Authors: Nyembe, Sanele , Chindeka, Francis , Ndlovu, Gebhu , Mkhohlakali, Andile , Nyokong, Tebello , Sikhwiyhilu, Lucy
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295783 , vital:57377 , xlink:href="https://doi.org/10.3390/nano12101715"
- Description: Plasmonic gold nanoparticles significantly improved the efficiency of a TiO2 and Eosin Y based dye-sensitized solar cell from 2.4 to 6.43%. The gold nanoparticles’ sizes that were tested were 14 nm, 30 nm and 40 nm synthesized via the systematic reduction of citrate concentration using the Turkevich method. Prestine TiO2 without plasmonic gold nanoparticles yielded an efficiency of 2.4%. However, the loading of 40 nm gold nanoparticles into the TiO2 matrix yielded the highest DSSC efficiency of 6.43% compared to 30 nm (5.91%) and 14 nm (2.6%). The relatively high efficiency demonstrated by plasmonic gold nanoparticles is ascribed to light absorption/scattering, hot electron injection and plasmon-induced resonance energy transfer (PIRET), influenced by the size of the gold nanoparticles.
- Full Text:
- Date Issued: 2022
- Authors: Nyembe, Sanele , Chindeka, Francis , Ndlovu, Gebhu , Mkhohlakali, Andile , Nyokong, Tebello , Sikhwiyhilu, Lucy
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295783 , vital:57377 , xlink:href="https://doi.org/10.3390/nano12101715"
- Description: Plasmonic gold nanoparticles significantly improved the efficiency of a TiO2 and Eosin Y based dye-sensitized solar cell from 2.4 to 6.43%. The gold nanoparticles’ sizes that were tested were 14 nm, 30 nm and 40 nm synthesized via the systematic reduction of citrate concentration using the Turkevich method. Prestine TiO2 without plasmonic gold nanoparticles yielded an efficiency of 2.4%. However, the loading of 40 nm gold nanoparticles into the TiO2 matrix yielded the highest DSSC efficiency of 6.43% compared to 30 nm (5.91%) and 14 nm (2.6%). The relatively high efficiency demonstrated by plasmonic gold nanoparticles is ascribed to light absorption/scattering, hot electron injection and plasmon-induced resonance energy transfer (PIRET), influenced by the size of the gold nanoparticles.
- Full Text:
- Date Issued: 2022
Expansive Learning and Transformative Agency for Equity and Sustainability: Formative Interventions in Six Continents
- Engeström, Yrjö, Bal, Aydin, Sannino, Annalisa, Morgado, Luciana P, de Gouveia Vilela, R A, Querol, Marco P, Lotz-Sisitka, Heila, Wei, Ge, Chikunda, Charles, Hopwood, Nick, Virkkunen, Jaakko, Mukute, Mutizwa
- Authors: Engeström, Yrjö , Bal, Aydin , Sannino, Annalisa , Morgado, Luciana P , de Gouveia Vilela, R A , Querol, Marco P , Lotz-Sisitka, Heila , Wei, Ge , Chikunda, Charles , Hopwood, Nick , Virkkunen, Jaakko , Mukute, Mutizwa
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , symposium
- Identifier: http://hdl.handle.net/10962/436688 , vital:73293 , ISBN 978-3-030-99347-4 , https://repository.isls.org//handle/1/8974
- Description: This double symposium brings together activity-theoretical formative intervention research conducted in six continents. The aim is to illuminate and examine the common threads, important differences, and new challenges of formative inter-vention studies to address “wicked problems” in different cul-tural, political, and economic contexts. Formative interven-tions facilitate expansive learning and systemic transfor-mation led by local stakeholders in organizations and social movements. The formative intervention methodology is based on the principles of double stimulation and ascending from the abstract to the concrete. Its most well-known appli-cation is the Change Laboratory method. Formative interven-tions generate and support expansive learning and trans-formative agency. The current global crises of climate change, poverty and deepening inequalities are giving rise to what is called fourth generation activity theory for tackling fateful challenges by building heterogenous multiactivity coa-litions. The symposium will present the theoretical and peda-gogical challenges and possibilities in Change Laboratories and other formative interventions to develop just and sus-tainable solutions to global crises.
- Full Text:
- Date Issued: 2022
- Authors: Engeström, Yrjö , Bal, Aydin , Sannino, Annalisa , Morgado, Luciana P , de Gouveia Vilela, R A , Querol, Marco P , Lotz-Sisitka, Heila , Wei, Ge , Chikunda, Charles , Hopwood, Nick , Virkkunen, Jaakko , Mukute, Mutizwa
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , symposium
- Identifier: http://hdl.handle.net/10962/436688 , vital:73293 , ISBN 978-3-030-99347-4 , https://repository.isls.org//handle/1/8974
- Description: This double symposium brings together activity-theoretical formative intervention research conducted in six continents. The aim is to illuminate and examine the common threads, important differences, and new challenges of formative inter-vention studies to address “wicked problems” in different cul-tural, political, and economic contexts. Formative interven-tions facilitate expansive learning and systemic transfor-mation led by local stakeholders in organizations and social movements. The formative intervention methodology is based on the principles of double stimulation and ascending from the abstract to the concrete. Its most well-known appli-cation is the Change Laboratory method. Formative interven-tions generate and support expansive learning and trans-formative agency. The current global crises of climate change, poverty and deepening inequalities are giving rise to what is called fourth generation activity theory for tackling fateful challenges by building heterogenous multiactivity coa-litions. The symposium will present the theoretical and peda-gogical challenges and possibilities in Change Laboratories and other formative interventions to develop just and sus-tainable solutions to global crises.
- Full Text:
- Date Issued: 2022
Exploring the community structure of Afrotropical macroinvertebrate traits and ecological preferences along an agricultural pollution gradient in the Kat River, Eastern Cape, South Africa
- Akamagwuna, Frank C, Odume, Oghenekaro N, Richoux, Nicole B
- Authors: Akamagwuna, Frank C , Odume, Oghenekaro N , Richoux, Nicole B
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454334 , vital:75336 , xlink:href="https://doi.org/10.1016/j.ecolind.2022.108570"
- Description: Agricultural activities impact riverine ecosystem structure, function, and processes. In the Afrotropical regions, research on agricultural effects on macroinvertebrate trait distribution is sparse. In this study, we investigated the spatial and temporal changes in the community structure of macroinvertebrate traits along an agricultural disturbance gradient in an Afrotropical River system. Physicochemical variables were sampled alongside macroinvertebrates at eight sites in the dry (winter and spring) and wet (summer and autumn) periods of 2018–2019. We grouped the sites into four categories using the percentage of agricultural land-use cover within each drainage area. Our results showed that agricultural pollution exhibited varying effects on traits and ecological preferences, with traits such as a predatory lifestyle, medium body-size (>10–20 mm), active swimming, possession of spiracles and haemoglobin, and adult aquatic life stage increasing with the pollution gradient. These traits were positively associated with nutrients (PO4+-P, NO2+-N, NH4+-N and NO3+-N), salinity, turbidity and temperature and were deemed tolerant of agricultural pollution. Shredding, crawling, and a preference for macrophytes as food showed strong positive associations with the least disturbed sites and were negatively associated with increasing nutrients, salinity, turbidity and water temperature. As such, these three traits were considered sensitive to agricultural pollution. The identified indicator traits can be used to predict the survival and distribution patterns of organisms under the impact of agriculture-induced stress.
- Full Text:
- Date Issued: 2022
- Authors: Akamagwuna, Frank C , Odume, Oghenekaro N , Richoux, Nicole B
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454334 , vital:75336 , xlink:href="https://doi.org/10.1016/j.ecolind.2022.108570"
- Description: Agricultural activities impact riverine ecosystem structure, function, and processes. In the Afrotropical regions, research on agricultural effects on macroinvertebrate trait distribution is sparse. In this study, we investigated the spatial and temporal changes in the community structure of macroinvertebrate traits along an agricultural disturbance gradient in an Afrotropical River system. Physicochemical variables were sampled alongside macroinvertebrates at eight sites in the dry (winter and spring) and wet (summer and autumn) periods of 2018–2019. We grouped the sites into four categories using the percentage of agricultural land-use cover within each drainage area. Our results showed that agricultural pollution exhibited varying effects on traits and ecological preferences, with traits such as a predatory lifestyle, medium body-size (>10–20 mm), active swimming, possession of spiracles and haemoglobin, and adult aquatic life stage increasing with the pollution gradient. These traits were positively associated with nutrients (PO4+-P, NO2+-N, NH4+-N and NO3+-N), salinity, turbidity and temperature and were deemed tolerant of agricultural pollution. Shredding, crawling, and a preference for macrophytes as food showed strong positive associations with the least disturbed sites and were negatively associated with increasing nutrients, salinity, turbidity and water temperature. As such, these three traits were considered sensitive to agricultural pollution. The identified indicator traits can be used to predict the survival and distribution patterns of organisms under the impact of agriculture-induced stress.
- Full Text:
- Date Issued: 2022
Fabrication of asymmetrical morpholine phthalocyanines conjugated chitosan-polyacrylonitrile nanofibers for improved photodynamic antimicrobial chemotherapy activity
- Sindelo, Azole, Mafukidze, Donovan M, Nyokong, Tebello
- Authors: Sindelo, Azole , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229873 , vital:49719 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.102760"
- Description: The work is based on the synthesis and photodynamic antimicrobial chemotherapy (PACT) activities of neutral (1 and 2) and cationic (1Q and 2Q) morpholine substituted phthalocyanines. For applicability, these complexes were covalently linked to modified polyacrylonitrile (PAN) to form 1-PAN, 2-PAN, 1Q-PAN, and 2Q-PAN, respectively. Chitosan was conjugated to PAN (to form PAN-CS) which was then linked to the Pcs to form PAN-CS-1, PAN-CS-2, PAN-CS-1Q, and PAN-CS-2Q, respectively. Singlet oxygen quantum yields improved following the inclusion of chitosan. The PACT activities of the complexes alone and when anchored to both PAN and PAN-CS was evaluated against bacteria: S. aureus, E. coli and fungi C. albicans. Cationic phthalocyanine showed high efficacy values of >7 log reduction value for all microorganisms. These results translated into excellent bacterial colony reduction of >90% against both S. aureus and C. albicans after 1 h of photoirradiation on PAN-CS support.
- Full Text:
- Date Issued: 2022
- Authors: Sindelo, Azole , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229873 , vital:49719 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.102760"
- Description: The work is based on the synthesis and photodynamic antimicrobial chemotherapy (PACT) activities of neutral (1 and 2) and cationic (1Q and 2Q) morpholine substituted phthalocyanines. For applicability, these complexes were covalently linked to modified polyacrylonitrile (PAN) to form 1-PAN, 2-PAN, 1Q-PAN, and 2Q-PAN, respectively. Chitosan was conjugated to PAN (to form PAN-CS) which was then linked to the Pcs to form PAN-CS-1, PAN-CS-2, PAN-CS-1Q, and PAN-CS-2Q, respectively. Singlet oxygen quantum yields improved following the inclusion of chitosan. The PACT activities of the complexes alone and when anchored to both PAN and PAN-CS was evaluated against bacteria: S. aureus, E. coli and fungi C. albicans. Cationic phthalocyanine showed high efficacy values of >7 log reduction value for all microorganisms. These results translated into excellent bacterial colony reduction of >90% against both S. aureus and C. albicans after 1 h of photoirradiation on PAN-CS support.
- Full Text:
- Date Issued: 2022
Framing of political leaders during the# BringBackOurGirls campaign by the Nigerian Press: a comparative study of Guardian and Vanguard Newspapers
- Akpojivi, Ufuoma, Aiseng, Kealeboga
- Authors: Akpojivi, Ufuoma , Aiseng, Kealeboga
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/455214 , vital:75413 , https://doi.org/10.3389/fcomm.2022.853673
- Description: This study examines Nigeria's political leaders' framing during the #BringBackOurGirls movement campaign using two selected national newspapers in Nigeria, i.e., the Guardian and the Vanguard newspa-pers. Using 46 news stories culled during the periods of April 14, 2014, to June 14, 2014, and May 29, 2015, to July 29, 2015, which represent two significant eras, i.e., when the schoolgirls were abducted, and when there was a change in government, the study argued that four frames of government failure, the desperation of citizens, politicization of gov-ernment actions and heroism were dominant in both presses reportage. During the first period of study, both presses were critical of President Goodluck Jonathan and his inability to secure the release of the ab-ducted Chibok schoolgirl as they used frames of “liar”, “clueless”, and “failure” amongst others to characterize his government actions and in-actions. However, during the second study period, both presses were less critical of President Buhari as they ascribed the “hero” frame to him due to his vast military experience. Nevertheless, the ideological posi-tion of both newspapers influenced their reportage as Guardian news stories provided depth analysis, while Vanguard newspaper stories lacked depth.
- Full Text:
- Date Issued: 2022
- Authors: Akpojivi, Ufuoma , Aiseng, Kealeboga
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/455214 , vital:75413 , https://doi.org/10.3389/fcomm.2022.853673
- Description: This study examines Nigeria's political leaders' framing during the #BringBackOurGirls movement campaign using two selected national newspapers in Nigeria, i.e., the Guardian and the Vanguard newspa-pers. Using 46 news stories culled during the periods of April 14, 2014, to June 14, 2014, and May 29, 2015, to July 29, 2015, which represent two significant eras, i.e., when the schoolgirls were abducted, and when there was a change in government, the study argued that four frames of government failure, the desperation of citizens, politicization of gov-ernment actions and heroism were dominant in both presses reportage. During the first period of study, both presses were critical of President Goodluck Jonathan and his inability to secure the release of the ab-ducted Chibok schoolgirl as they used frames of “liar”, “clueless”, and “failure” amongst others to characterize his government actions and in-actions. However, during the second study period, both presses were less critical of President Buhari as they ascribed the “hero” frame to him due to his vast military experience. Nevertheless, the ideological posi-tion of both newspapers influenced their reportage as Guardian news stories provided depth analysis, while Vanguard newspaper stories lacked depth.
- Full Text:
- Date Issued: 2022
From affirmative to transformative approaches to academic development
- McKenna, Sioux, Hlengwa, Amanda, Quinn, Lyn, Vorster, Jo-Anne E
- Authors: McKenna, Sioux , Hlengwa, Amanda , Quinn, Lyn , Vorster, Jo-Anne E
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426651 , vital:72375 , xlink:href="https://doi.org/10.1080/13562517.2022.2119077"
- Description: Much academic development work, whether it be student, academic staff, institutional or curriculum development, is undertaken from an affirmative rather than a transformative approach (Luckett, L., and S. Shay. 2020.“Reframing the Curriculum: A Transformative Approach.” Critical Studies in Education61 (1): 50–65). To be transformative, academic development has to reframe the problem beyond one of poor student retention and throughput. We need to make sense of the conditions from which issues such as poor retention and throughput rates emerge, rather than focusing on mitigating the effects of such conditions within the status quo. Drawing on Fraser’s concept of parity of participation, we suggest that if academic development is to engage in transformative approaches, it needs to adjust the scale of the problem and challenge underpinning assumptions, and thereby review the fitness of universities, curricula and academic development practices for a pluralist society. In sum, a transformative approach to academic development work will entail conceptualising academic development as a political knowledge project.
- Full Text:
- Date Issued: 2022
- Authors: McKenna, Sioux , Hlengwa, Amanda , Quinn, Lyn , Vorster, Jo-Anne E
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426651 , vital:72375 , xlink:href="https://doi.org/10.1080/13562517.2022.2119077"
- Description: Much academic development work, whether it be student, academic staff, institutional or curriculum development, is undertaken from an affirmative rather than a transformative approach (Luckett, L., and S. Shay. 2020.“Reframing the Curriculum: A Transformative Approach.” Critical Studies in Education61 (1): 50–65). To be transformative, academic development has to reframe the problem beyond one of poor student retention and throughput. We need to make sense of the conditions from which issues such as poor retention and throughput rates emerge, rather than focusing on mitigating the effects of such conditions within the status quo. Drawing on Fraser’s concept of parity of participation, we suggest that if academic development is to engage in transformative approaches, it needs to adjust the scale of the problem and challenge underpinning assumptions, and thereby review the fitness of universities, curricula and academic development practices for a pluralist society. In sum, a transformative approach to academic development work will entail conceptualising academic development as a political knowledge project.
- Full Text:
- Date Issued: 2022
From imperialism to radical hospitality: propositions for reconfiguring social work towards a justice-to-come
- Bozalek, Vivienne, Holscher, Dorothee
- Authors: Bozalek, Vivienne , Holscher, Dorothee
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426904 , vital:72399 , xlink:href="https://doi.org/10.25159/2708-9355/8889"
- Description: The focus of the article is on injustices towards South African families in postcolonial and neocolonial contexts, our understanding of which has been greatly enlarged by Nancy Fraser’s conceptualisations of expropriation and imperialism and Jacques Derrida’s notions of hostility and hospitality. We used Walter Benjamin’s and Karen Barad’s montage methods of fragmentary writing to diffractively read expropriation, imperialism, hostility and hospitality through one another in the context of injustices done to South African families. A diffractive methodology entails a close and attentive reading of concepts or pieces of text through one another, to arrive at new insights with regard to a particular issue. The new insights we arrive at in the article are five propositions for ethically engaging in a justice-to-come for social work – that of attentiveness, rendering each other capable, responsibility, response-ability and radical hospitality.
- Full Text:
- Date Issued: 2022
- Authors: Bozalek, Vivienne , Holscher, Dorothee
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426904 , vital:72399 , xlink:href="https://doi.org/10.25159/2708-9355/8889"
- Description: The focus of the article is on injustices towards South African families in postcolonial and neocolonial contexts, our understanding of which has been greatly enlarged by Nancy Fraser’s conceptualisations of expropriation and imperialism and Jacques Derrida’s notions of hostility and hospitality. We used Walter Benjamin’s and Karen Barad’s montage methods of fragmentary writing to diffractively read expropriation, imperialism, hostility and hospitality through one another in the context of injustices done to South African families. A diffractive methodology entails a close and attentive reading of concepts or pieces of text through one another, to arrive at new insights with regard to a particular issue. The new insights we arrive at in the article are five propositions for ethically engaging in a justice-to-come for social work – that of attentiveness, rendering each other capable, responsibility, response-ability and radical hospitality.
- Full Text:
- Date Issued: 2022
Fuelwood in South Africa Revisited: Widespread Use in a Policy Vacuum
- Shackleton, Charlie M, Sinasson, Gisele, Adeyemi, Opeyemi, Martins, Vusumzi
- Authors: Shackleton, Charlie M , Sinasson, Gisele , Adeyemi, Opeyemi , Martins, Vusumzi
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/402275 , vital:69837 , xlink:href="https://doi.org/10.3390/su141711018"
- Description: South Africa has experienced massive urbanisation and socioeconomic development over the past two decades. Concomitantly, the national energy policy focuses on the provision of modern fuels, notably electricity, for domestic use. Given this policy environment and socioeconomic development, we examine pertinent literature and policies from South Africa on fuelwood use, value, and sustainability to understand how it might have changed in tandem with the national shifts in urbanisation and socioeconomic development over the last 20 years. Recent literature shows that fuelwood is still used to some extent by 96% of rural households and 69% of low-income urban ones. We also estimate that the use of fuelwood by rural households alone is valued at approximately ZAR 10.5 billion (approx. USD 700 million) annually, with the probability of an equally high value to low-income urban households. However, despite the extensive use and high value, our analysis of cognate national policies related to energy, forestry, environment, and social development, show that fuelwood and its use is hardly considered, indicating a policy vacuum. This policy vacuum means that there is no strategic or apposite support or interventions in any localised areas where fuelwood demand might exceed supply, thereby undermining the livelihoods and energy security of affected citizens, most notably the poor.
- Full Text:
- Date Issued: 2022
- Authors: Shackleton, Charlie M , Sinasson, Gisele , Adeyemi, Opeyemi , Martins, Vusumzi
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/402275 , vital:69837 , xlink:href="https://doi.org/10.3390/su141711018"
- Description: South Africa has experienced massive urbanisation and socioeconomic development over the past two decades. Concomitantly, the national energy policy focuses on the provision of modern fuels, notably electricity, for domestic use. Given this policy environment and socioeconomic development, we examine pertinent literature and policies from South Africa on fuelwood use, value, and sustainability to understand how it might have changed in tandem with the national shifts in urbanisation and socioeconomic development over the last 20 years. Recent literature shows that fuelwood is still used to some extent by 96% of rural households and 69% of low-income urban ones. We also estimate that the use of fuelwood by rural households alone is valued at approximately ZAR 10.5 billion (approx. USD 700 million) annually, with the probability of an equally high value to low-income urban households. However, despite the extensive use and high value, our analysis of cognate national policies related to energy, forestry, environment, and social development, show that fuelwood and its use is hardly considered, indicating a policy vacuum. This policy vacuum means that there is no strategic or apposite support or interventions in any localised areas where fuelwood demand might exceed supply, thereby undermining the livelihoods and energy security of affected citizens, most notably the poor.
- Full Text:
- Date Issued: 2022
Fuelwood Production and Carbon Sequestration in Public Urban Green Spaces in Bulawayo, Zimbabwe
- Ngulani, Thembelihle, Shackleton, Charlie M
- Authors: Ngulani, Thembelihle , Shackleton, Charlie M
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438757 , vital:73497 , xlink:href="https://doi.org/10.3390/f13050741"
- Description: Understanding tree species autecology and population structure supports effective conservation actions. Of particular importance are multipurpose trees that provide non-timber forest products (NTFPs). We assessed the population structures and morphologies of two species of NTFP trees in the genus Mimusops across bioclimatic zones in Benin by sampling 288 plots within 11 forests. Structural characteristics were compared between species, forests and zones. Correlations were also observed between Mimusops tree regeneration density, tree features and ecological characteristics. The density of trees ≥5 cm and of regeneration and mean tree height were higher for M. andongensis (within more protected forest) than M. kummel (in forests with access to people), while the highest mean diameter was observed for M. kummel. Tree and regeneration densities and mean height were greatest in the humid zone of Benin, whilst the largest mean diameter was obtained in the sub-humid zone. The results showed significant correlations between regeneration density and soil properties for M. andongensis but not for M. kummel. The correlations between tree morphology and soil characteristics were weak for both species. Ecological characteristics, along with the species’ functional traits and pressures, are important factors related to the observed differences between the species. All diameter classes were represented, and the population seemed more stable in the more protected forest relative to other forests. Mimusops trees with a diameter of 5–15 cm represented more than 30% of this species in most forests; this suggests, for M. kummel, whose trees flower when quite small (≥6 cm dbh), that there are sufficient reproductive trees. Thus, as a long-lived species, its populations could be maintained even with low/episodic recruitment. However, we found no regeneration in many forests and climate change could threaten populations. Therefore, it is important to investigate regeneration growth and dynamics, seed production and germination of the species in relation to the biophysical conditions and disturbances experienced by Mimusops stands.
- Full Text:
- Date Issued: 2022
- Authors: Ngulani, Thembelihle , Shackleton, Charlie M
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438757 , vital:73497 , xlink:href="https://doi.org/10.3390/f13050741"
- Description: Understanding tree species autecology and population structure supports effective conservation actions. Of particular importance are multipurpose trees that provide non-timber forest products (NTFPs). We assessed the population structures and morphologies of two species of NTFP trees in the genus Mimusops across bioclimatic zones in Benin by sampling 288 plots within 11 forests. Structural characteristics were compared between species, forests and zones. Correlations were also observed between Mimusops tree regeneration density, tree features and ecological characteristics. The density of trees ≥5 cm and of regeneration and mean tree height were higher for M. andongensis (within more protected forest) than M. kummel (in forests with access to people), while the highest mean diameter was observed for M. kummel. Tree and regeneration densities and mean height were greatest in the humid zone of Benin, whilst the largest mean diameter was obtained in the sub-humid zone. The results showed significant correlations between regeneration density and soil properties for M. andongensis but not for M. kummel. The correlations between tree morphology and soil characteristics were weak for both species. Ecological characteristics, along with the species’ functional traits and pressures, are important factors related to the observed differences between the species. All diameter classes were represented, and the population seemed more stable in the more protected forest relative to other forests. Mimusops trees with a diameter of 5–15 cm represented more than 30% of this species in most forests; this suggests, for M. kummel, whose trees flower when quite small (≥6 cm dbh), that there are sufficient reproductive trees. Thus, as a long-lived species, its populations could be maintained even with low/episodic recruitment. However, we found no regeneration in many forests and climate change could threaten populations. Therefore, it is important to investigate regeneration growth and dynamics, seed production and germination of the species in relation to the biophysical conditions and disturbances experienced by Mimusops stands.
- Full Text:
- Date Issued: 2022
Ga III triarylcorroles with push–pull substitutions
- Niu, Yingjie, Wang, Lin, Guo, Yingxin, Zhu, Weihua, Soy, Rodah C, Babu, Balaji, Mack, John, Nyokong, Tebello, Xu, Haijun, Liang, Xu
- Authors: Niu, Yingjie , Wang, Lin , Guo, Yingxin , Zhu, Weihua , Soy, Rodah C , Babu, Balaji , Mack, John , Nyokong, Tebello , Xu, Haijun , Liang, Xu
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300079 , vital:57890 , xlink:href="https://doi.org/10.1039/D2DT01262F"
- Description: Two A2B type H3corroles and two GaIIItriarylcorroles with carbazole substitutions at 10-positions were synthesized and characterized. An analysis of structure–property relationships of the corroles has been carried out by investigating the optical spectroscopy of the dyes to trends predicted in DFT and TD-DFT calculations. Interestingly, the photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) activity properties of the GaIIItriarylcorroles were determined against the MCF-7 breast cancer line, and Staphyloccocus aureus (S. aureus) and Escherichia coli (E. coli), respectively. The cationic G-2Q species exhibited the most favorable properties with an IC50 value of 7.8 μM against MCF-7 cells, and Log reduction values of 7.78 and 3.26 against planktonic S. aureus and E. coli at 0.5 and 10 μM, respectively.
- Full Text:
- Date Issued: 2022
- Authors: Niu, Yingjie , Wang, Lin , Guo, Yingxin , Zhu, Weihua , Soy, Rodah C , Babu, Balaji , Mack, John , Nyokong, Tebello , Xu, Haijun , Liang, Xu
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300079 , vital:57890 , xlink:href="https://doi.org/10.1039/D2DT01262F"
- Description: Two A2B type H3corroles and two GaIIItriarylcorroles with carbazole substitutions at 10-positions were synthesized and characterized. An analysis of structure–property relationships of the corroles has been carried out by investigating the optical spectroscopy of the dyes to trends predicted in DFT and TD-DFT calculations. Interestingly, the photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) activity properties of the GaIIItriarylcorroles were determined against the MCF-7 breast cancer line, and Staphyloccocus aureus (S. aureus) and Escherichia coli (E. coli), respectively. The cationic G-2Q species exhibited the most favorable properties with an IC50 value of 7.8 μM against MCF-7 cells, and Log reduction values of 7.78 and 3.26 against planktonic S. aureus and E. coli at 0.5 and 10 μM, respectively.
- Full Text:
- Date Issued: 2022
Household dietary patterns and food security challenges in Peri-Urban South Africa: A reflection of high unemployment in the wake of rising food prices
- Authors: Chakona, Gamuchirai
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433943 , vital:73013 , ISBN 978-3-030-93072-1 , https://doi.org/10.1007/978-3-030-93072-1_11
- Description: Urbanization is one of the major social changes sweeping the globe, with rapid growth of the urban population and stagnating growth of the rural population, especially in developing regions (UN-Habitat, 2020). In subSaharan Africa, rapid urbanization and poverty are the major fundamental development challenges that are perpetuating and deepening the crisis of food and nutrition insecurity in urban areas (Battersby, 2012). Many people living in urban areas face under-nutrition, mainly due to their lack of income rather than to a lack of capacity to produce food (Satterthwaite et al., 2010). The health and nutritional status of urban populations with very low incomes are at risk from rising prices in staple foods. This became evident with the rising hunger among urban populations after the food price rises in 2007 and the first half of 2008 (Cohen and Garrett, 2009). In South Africa, poverty, unemployment and high food prices are dominant and influence dietary change, which subsequently increases urban food insecurity and malnutrition (Battersby, 2012).
- Full Text:
- Date Issued: 2022
- Authors: Chakona, Gamuchirai
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433943 , vital:73013 , ISBN 978-3-030-93072-1 , https://doi.org/10.1007/978-3-030-93072-1_11
- Description: Urbanization is one of the major social changes sweeping the globe, with rapid growth of the urban population and stagnating growth of the rural population, especially in developing regions (UN-Habitat, 2020). In subSaharan Africa, rapid urbanization and poverty are the major fundamental development challenges that are perpetuating and deepening the crisis of food and nutrition insecurity in urban areas (Battersby, 2012). Many people living in urban areas face under-nutrition, mainly due to their lack of income rather than to a lack of capacity to produce food (Satterthwaite et al., 2010). The health and nutritional status of urban populations with very low incomes are at risk from rising prices in staple foods. This became evident with the rising hunger among urban populations after the food price rises in 2007 and the first half of 2008 (Cohen and Garrett, 2009). In South Africa, poverty, unemployment and high food prices are dominant and influence dietary change, which subsequently increases urban food insecurity and malnutrition (Battersby, 2012).
- Full Text:
- Date Issued: 2022
How many people globally actually use non-timber forest products?
- Shackleton, Charlie M, de Vos, Alta
- Authors: Shackleton, Charlie M , de Vos, Alta
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/403200 , vital:69933 , xlink:href="https://doi.org/10.1016/j.forpol.2021.102659"
- Description: Non-timber forest products (NTFPs) are widely used wild, biological products harvested from rural and urban landscapes for household subsistence, income and culture, thereby contributing to human wellbeing. Estimates of the numbers of people making use of, or being dependent on, NTFPs vary widely, and global estimates to date have excluded urban populations and also NTFP users in the Global North. Additionally, most global or continental estimates are two or more decades old, and hence do not account for significant worldwide changes in societies, cultures, economies and landscapes since the estimates were made. Here we collate more recent empirical studies reporting the number of NTFP users at fine scales that we extrapolate up for three broad regions, viz. rural areas of the Global South, urban areas of the Global South, and the Global North, as the basis for estimating the number of NTFP users globally. We calculate the lower and upper bounds, as well a median estimate. We find the lowest and median approximations to be 3.5 billion and 5.76 billion users globally, respectively, based on conservative approaches. This is more than double and triple, respectively, the oft cited and dated figure of 1.6 billion. Moreover, we find that only half of the global NTFP users are located in rural regions of the Global South, and that the other half are in urban areas and the Global North, showing that NTFPs are of importance across socio-economic and geographic regions, not just in remote and underdeveloped villages of the Global South. With such large numbers of users around the world, it is imperative that the supply, management, conservation and safeguarding of the values of NTFPs take a more central place in sectoral and development policies.
- Full Text:
- Date Issued: 2022
- Authors: Shackleton, Charlie M , de Vos, Alta
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/403200 , vital:69933 , xlink:href="https://doi.org/10.1016/j.forpol.2021.102659"
- Description: Non-timber forest products (NTFPs) are widely used wild, biological products harvested from rural and urban landscapes for household subsistence, income and culture, thereby contributing to human wellbeing. Estimates of the numbers of people making use of, or being dependent on, NTFPs vary widely, and global estimates to date have excluded urban populations and also NTFP users in the Global North. Additionally, most global or continental estimates are two or more decades old, and hence do not account for significant worldwide changes in societies, cultures, economies and landscapes since the estimates were made. Here we collate more recent empirical studies reporting the number of NTFP users at fine scales that we extrapolate up for three broad regions, viz. rural areas of the Global South, urban areas of the Global South, and the Global North, as the basis for estimating the number of NTFP users globally. We calculate the lower and upper bounds, as well a median estimate. We find the lowest and median approximations to be 3.5 billion and 5.76 billion users globally, respectively, based on conservative approaches. This is more than double and triple, respectively, the oft cited and dated figure of 1.6 billion. Moreover, we find that only half of the global NTFP users are located in rural regions of the Global South, and that the other half are in urban areas and the Global North, showing that NTFPs are of importance across socio-economic and geographic regions, not just in remote and underdeveloped villages of the Global South. With such large numbers of users around the world, it is imperative that the supply, management, conservation and safeguarding of the values of NTFPs take a more central place in sectoral and development policies.
- Full Text:
- Date Issued: 2022
How the Teaching Development Grant was used (and the problem of common-sense understandings of teaching and learning)
- Moyo, Temwa, McKenna, Sioux, Ndebele, Clever
- Authors: Moyo, Temwa , McKenna, Sioux , Ndebele, Clever
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426917 , vital:72400 , xlink:href="http://dx.doi.org/10.17159/2520-9868/i86a07"
- Description: Teachers at primary and secondary education levels are required to hold a professional qualification but, at the higher education level, all that is required is content expertise. This may well contribute to South Africa's low university throughput and retention rates, in response to which, since 2004, the state has provided ZAR5.5 billion in the form of the Teaching Development Grant (now the University Capacity Development Grant) to address poor completion rates. We present an analysis of the use of the grant across the sector using a social realist framework. Every academic and student has themselves been taught and so have developed untheorised assumptions about curriculum and pedagogy. Such common-sense assumptions about teaching and learning often serve to reinforce the status quo, which is particularly problematic in a sector with poor and racially differentiated throughput and success rates. Many initiatives funded through the grant evidenced a reliance on common-sense assumptions rather than on theorised accounts. In particular, student development often took the form of remedial, add-on initiatives that left the mainstream curriculum untouched-and staff development was often generic and short term. We also found that expertise in academic development, which could potentially challenge common-sense assumptions, was unevenly distributed.
- Full Text:
- Date Issued: 2022
- Authors: Moyo, Temwa , McKenna, Sioux , Ndebele, Clever
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426917 , vital:72400 , xlink:href="http://dx.doi.org/10.17159/2520-9868/i86a07"
- Description: Teachers at primary and secondary education levels are required to hold a professional qualification but, at the higher education level, all that is required is content expertise. This may well contribute to South Africa's low university throughput and retention rates, in response to which, since 2004, the state has provided ZAR5.5 billion in the form of the Teaching Development Grant (now the University Capacity Development Grant) to address poor completion rates. We present an analysis of the use of the grant across the sector using a social realist framework. Every academic and student has themselves been taught and so have developed untheorised assumptions about curriculum and pedagogy. Such common-sense assumptions about teaching and learning often serve to reinforce the status quo, which is particularly problematic in a sector with poor and racially differentiated throughput and success rates. Many initiatives funded through the grant evidenced a reliance on common-sense assumptions rather than on theorised accounts. In particular, student development often took the form of remedial, add-on initiatives that left the mainstream curriculum untouched-and staff development was often generic and short term. We also found that expertise in academic development, which could potentially challenge common-sense assumptions, was unevenly distributed.
- Full Text:
- Date Issued: 2022
Hybrid approaches to teaching: Re-imagining the teaching of a foundational science course during a global pandemic
- Parker, Daniel M, Vorster, Jo-Anne E, Quinn, Lynn, Blackie, Margaret A L
- Authors: Parker, Daniel M , Vorster, Jo-Anne E , Quinn, Lynn , Blackie, Margaret A L
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426662 , vital:72377 , xlink:href="https://www.ajol.info/index.php/cristal/article/view/240803"
- Description: Access to scientific knowledge, and teaching in the sciences, is believed to be about training because scientific knowledge is, generally, specialised. However, for students to gain full epistemological access in the sciences, they also need to be inducted as scientists and learners of science. We use Bernstein’s regulative and instructional discourse to engage with the notion of epistemological access and effectiveness of a foundational science course. We examine how the course can cultivate scientific identities amongst first year students at a recently established South African university. Our analysis assesses the impact of the forced shift from contact teaching to Emergency Remote Teaching due to the COVID-19 pandemic. We demonstrate that the course was able to begin to facilitate the cultivation of different kinds of knowers in science. However, several gaps remain. Thus, we argue that foundational science lecturers should focus on hybrid teaching approaches to promote enhanced learning amongst students.
- Full Text:
- Date Issued: 2022
- Authors: Parker, Daniel M , Vorster, Jo-Anne E , Quinn, Lynn , Blackie, Margaret A L
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426662 , vital:72377 , xlink:href="https://www.ajol.info/index.php/cristal/article/view/240803"
- Description: Access to scientific knowledge, and teaching in the sciences, is believed to be about training because scientific knowledge is, generally, specialised. However, for students to gain full epistemological access in the sciences, they also need to be inducted as scientists and learners of science. We use Bernstein’s regulative and instructional discourse to engage with the notion of epistemological access and effectiveness of a foundational science course. We examine how the course can cultivate scientific identities amongst first year students at a recently established South African university. Our analysis assesses the impact of the forced shift from contact teaching to Emergency Remote Teaching due to the COVID-19 pandemic. We demonstrate that the course was able to begin to facilitate the cultivation of different kinds of knowers in science. However, several gaps remain. Thus, we argue that foundational science lecturers should focus on hybrid teaching approaches to promote enhanced learning amongst students.
- Full Text:
- Date Issued: 2022
IFRS and FPI nexus: does the quality of the institutional framework matter for African countries?
- Simbi, Chipo, Arendse, Jacqueline A, Khumalo, Sibanisezwe A
- Authors: Simbi, Chipo , Arendse, Jacqueline A , Khumalo, Sibanisezwe A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426448 , vital:72354 , xlink:href="https://doi.org/10.1108/JAEE-10-2021-0319"
- Description: The institutional framework of an African country may influence the effectiveness of the International Financial Reporting Standards (IFRS) on foreign investment inflows. The purpose of this paper is to argue that the quality of a country's institutional framework impacts the effectiveness of IFRS to an adopting country and ultimately influences the levels of Foreign Portfolio Investment (FPI).
- Full Text:
- Date Issued: 2022
- Authors: Simbi, Chipo , Arendse, Jacqueline A , Khumalo, Sibanisezwe A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426448 , vital:72354 , xlink:href="https://doi.org/10.1108/JAEE-10-2021-0319"
- Description: The institutional framework of an African country may influence the effectiveness of the International Financial Reporting Standards (IFRS) on foreign investment inflows. The purpose of this paper is to argue that the quality of a country's institutional framework impacts the effectiveness of IFRS to an adopting country and ultimately influences the levels of Foreign Portfolio Investment (FPI).
- Full Text:
- Date Issued: 2022
Impedimetric aptasensor for HER2 biomarker using graphene quantum dots, polypyrrole and cobalt phthalocyanine modified electrodes
- Centane, Sixolile, Nyokong, Tebello
- Authors: Centane, Sixolile , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230960 , vital:49836 , xlink:href="https://doi.org/10.1016/j.sbsr.2021.100467"
- Description: A method is presented for the electrochemical detection of the breast cancer biomarker human epidermal growth factor receptor 2 (HER2). A glassy carbon electrode was modified using two techniques known as sequential adsorption and electro-polymerization, and the results are compared. The highly conductive polypyrrole (PPy) is used, in the presence of sulfur/nitrogen doped graphene quantum dots (SNGQDs) and a known cobalt phthalocyanine (CoPc). The different nanomaterials were used as an immobilization platform for the HER2 specific HB5 aptamer via amide linkage. The nanomaterials were arranged in various ways on the glassy carbon electrode, to investigate the effect of the electrode interface on the operational characteristics of a biosensor. The immobilized aptamer selectively recognizes HER2 on the electrode interface, and this leads to an increased charge transfer resistance (Rct) of the electrode when using ferricyanide as the electrochemical probe. The developed immunosensors showed high sensitivity with the best detection limit of 0.00141 ng/mL. The results showed that the method is simple and sensitive enough for the determination of HER2 in serum samples with good reproducibility and accuracy.
- Full Text:
- Date Issued: 2022
- Authors: Centane, Sixolile , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230960 , vital:49836 , xlink:href="https://doi.org/10.1016/j.sbsr.2021.100467"
- Description: A method is presented for the electrochemical detection of the breast cancer biomarker human epidermal growth factor receptor 2 (HER2). A glassy carbon electrode was modified using two techniques known as sequential adsorption and electro-polymerization, and the results are compared. The highly conductive polypyrrole (PPy) is used, in the presence of sulfur/nitrogen doped graphene quantum dots (SNGQDs) and a known cobalt phthalocyanine (CoPc). The different nanomaterials were used as an immobilization platform for the HER2 specific HB5 aptamer via amide linkage. The nanomaterials were arranged in various ways on the glassy carbon electrode, to investigate the effect of the electrode interface on the operational characteristics of a biosensor. The immobilized aptamer selectively recognizes HER2 on the electrode interface, and this leads to an increased charge transfer resistance (Rct) of the electrode when using ferricyanide as the electrochemical probe. The developed immunosensors showed high sensitivity with the best detection limit of 0.00141 ng/mL. The results showed that the method is simple and sensitive enough for the determination of HER2 in serum samples with good reproducibility and accuracy.
- Full Text:
- Date Issued: 2022
Improving the mental health of women intimate partner violence survivors: Findings from a realist review of psychosocial interventions
- Paphitis, Sharli A, Bentley, Abigail, Asher, Laura, Osrin, David, Oram, Sian
- Authors: Paphitis, Sharli A , Bentley, Abigail , Asher, Laura , Osrin, David , Oram, Sian
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426453 , vital:72355 , xlink:href="https://doi.org/10.1371/journal.pone.0264845"
- Description: Intimate partner violence (IPV) is highly prevalent and is associated with a range of mental health problems. A broad range of psychosocial interventions have been developed to support the recovery of women survivors of IPV, but their mechanisms of action remain unclear.
- Full Text:
- Date Issued: 2022
- Authors: Paphitis, Sharli A , Bentley, Abigail , Asher, Laura , Osrin, David , Oram, Sian
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426453 , vital:72355 , xlink:href="https://doi.org/10.1371/journal.pone.0264845"
- Description: Intimate partner violence (IPV) is highly prevalent and is associated with a range of mental health problems. A broad range of psychosocial interventions have been developed to support the recovery of women survivors of IPV, but their mechanisms of action remain unclear.
- Full Text:
- Date Issued: 2022
In vitro photoinactivation of S. aureus and photocatalytic degradation of tetracycline by novel phthalocyanine-graphene quantum dots nano-assemblies
- Openda, Yolande Ikala, Mgidlana, Sithi, Nyokong, Tebello
- Authors: Openda, Yolande Ikala , Mgidlana, Sithi , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229895 , vital:49721 , xlink:href="https://doi.org/10.1016/j.jlumin.2022.118863"
- Description: A novel asymmetrical zinc (II) phthalocyanine (Pc) 4 bearing three dimethoxy groups and one carboxyl group was linked to glutathione capped graphene quantum dots (GQDs) by the reaction of carboxylic acid substituent on Pc 4 with the amino group on the GQDs. On the other side, the symmetrical Pc analog 3 was linked to the same nanoparticles through π-π interactions. The as-formed nano-photosensitizers were fully characterized by spectroscopic methods and their photophysicochemical properties were investigated as well. Photodynamic antimicrobial chemotherapy was performed on the planktonic cells of S. aureus strain. And the results show that these nano assemblies were able to completely inhibit the metabolic activity of the resistant bacteria strain S. aureus with a 10.26 log reduction in the viable count. Again, asymmetrical Pc showed higher photocatalytic activity compared to the symmetrical complex with higher kobs and fast initial rates for the former. The photocatalysis obeyed the Langmuir-Hinshelwood kinetic model. The target conjugates showed all the advantages of two different groups existing on a single entity.
- Full Text:
- Date Issued: 2022
- Authors: Openda, Yolande Ikala , Mgidlana, Sithi , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229895 , vital:49721 , xlink:href="https://doi.org/10.1016/j.jlumin.2022.118863"
- Description: A novel asymmetrical zinc (II) phthalocyanine (Pc) 4 bearing three dimethoxy groups and one carboxyl group was linked to glutathione capped graphene quantum dots (GQDs) by the reaction of carboxylic acid substituent on Pc 4 with the amino group on the GQDs. On the other side, the symmetrical Pc analog 3 was linked to the same nanoparticles through π-π interactions. The as-formed nano-photosensitizers were fully characterized by spectroscopic methods and their photophysicochemical properties were investigated as well. Photodynamic antimicrobial chemotherapy was performed on the planktonic cells of S. aureus strain. And the results show that these nano assemblies were able to completely inhibit the metabolic activity of the resistant bacteria strain S. aureus with a 10.26 log reduction in the viable count. Again, asymmetrical Pc showed higher photocatalytic activity compared to the symmetrical complex with higher kobs and fast initial rates for the former. The photocatalysis obeyed the Langmuir-Hinshelwood kinetic model. The target conjugates showed all the advantages of two different groups existing on a single entity.
- Full Text:
- Date Issued: 2022
Indium phthalocyanines
- Pinar, Sen, Mack, John, Nyokong, Tebello
- Authors: Pinar, Sen , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229998 , vital:49731 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.131850"
- Description: In this study, the photodynamic antimicrobial activities of a series of new tetra-substituted indium phthalocyanine (InPc) complexes are assessed. An aldehyde substituted complex (2) was initially prepared, which was converted through a condensatioreaction to an imine-pyrrolidine substituted complex (3), which in turn was quaternized to form a tetracationic species (4). Favorable photophysicochemical properties were obtained by incorporating a heavy In(III) ion into the central cavity. Aggregation studies revealed that 2–4 remain non-aggregated in DMSO at concentration below 25 µM. The photodeactivation of S.aureus and E.coli was studied. Log reduction values > 9.0 were obtained for cationic InPc 4 after 30 min of incubation and exposure to light for 75 min.
- Full Text:
- Date Issued: 2022
- Authors: Pinar, Sen , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229998 , vital:49731 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.131850"
- Description: In this study, the photodynamic antimicrobial activities of a series of new tetra-substituted indium phthalocyanine (InPc) complexes are assessed. An aldehyde substituted complex (2) was initially prepared, which was converted through a condensatioreaction to an imine-pyrrolidine substituted complex (3), which in turn was quaternized to form a tetracationic species (4). Favorable photophysicochemical properties were obtained by incorporating a heavy In(III) ion into the central cavity. Aggregation studies revealed that 2–4 remain non-aggregated in DMSO at concentration below 25 µM. The photodeactivation of S.aureus and E.coli was studied. Log reduction values > 9.0 were obtained for cationic InPc 4 after 30 min of incubation and exposure to light for 75 min.
- Full Text:
- Date Issued: 2022
Insights into the Dynamics and Binding of Two Polyprotein Substrate Cleavage Points in the Context of the SARS-CoV-2 Main and Papain-like Proteases
- Sanusi, Zainab K, Lobb, Kevin A
- Authors: Sanusi, Zainab K , Lobb, Kevin A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452773 , vital:75169 , xlink:href="https://doi.org/10.3390/molecules27238251"
- Description: It is well known that vital enzymes in the replication process of the coronavirus are the SARS-CoV-2 PLpro and SARS-CoV-2 3CLpro, both of which are important targets in the search for anti-coronavirus agents. These two enzymes are responsible for cleavage at various polyprotein sites in the SARS-CoV-2 lifecycle. Herein, the dynamics of the polyprotein cleavage sequences for the boundary between non-structural proteins Nsp1 and Nsp2 (CS1) and between Nsp2 and Nsp3 (CS2) in complex with both the papain-like protein PLpro and the main protease 3CLpro were explored using computational methods. The post dynamics analysis reveals that CS1 and CS2 both have greater stability when complexed with PLpro. Of these two, greater stability is observed for the CS1–PLpro complex, while destabilization resulting in loss of CS2 from the PLpro active site is observed for CS2-PLpro, suggesting the rate of exchange by the papain-like protease is faster for CS2 compared to CS1. On the other hand, the 3CLpro main protease also reveals stability for CS1 suggesting that the main protease could also play a potential role in the cleavage at point CS1. However, destabilization occurs early in the simulation for the complex CLpro–CS2 suggesting a poor interaction and non-plausible protease cleavage of the polyprotein at CS2 by the main protease. These findings could be used as a guide in the development and design of potent COVID-19 antiviral inhibitors that mimic the CS1 cleavage site.
- Full Text:
- Date Issued: 2022
- Authors: Sanusi, Zainab K , Lobb, Kevin A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452773 , vital:75169 , xlink:href="https://doi.org/10.3390/molecules27238251"
- Description: It is well known that vital enzymes in the replication process of the coronavirus are the SARS-CoV-2 PLpro and SARS-CoV-2 3CLpro, both of which are important targets in the search for anti-coronavirus agents. These two enzymes are responsible for cleavage at various polyprotein sites in the SARS-CoV-2 lifecycle. Herein, the dynamics of the polyprotein cleavage sequences for the boundary between non-structural proteins Nsp1 and Nsp2 (CS1) and between Nsp2 and Nsp3 (CS2) in complex with both the papain-like protein PLpro and the main protease 3CLpro were explored using computational methods. The post dynamics analysis reveals that CS1 and CS2 both have greater stability when complexed with PLpro. Of these two, greater stability is observed for the CS1–PLpro complex, while destabilization resulting in loss of CS2 from the PLpro active site is observed for CS2-PLpro, suggesting the rate of exchange by the papain-like protease is faster for CS2 compared to CS1. On the other hand, the 3CLpro main protease also reveals stability for CS1 suggesting that the main protease could also play a potential role in the cleavage at point CS1. However, destabilization occurs early in the simulation for the complex CLpro–CS2 suggesting a poor interaction and non-plausible protease cleavage of the polyprotein at CS2 by the main protease. These findings could be used as a guide in the development and design of potent COVID-19 antiviral inhibitors that mimic the CS1 cleavage site.
- Full Text:
- Date Issued: 2022