The trophic position and isotopic niche of a cryptogenic tube-building polychaete in a protected clear-water estuarine bay
- van Rensburg, Hendre, Richoux, Nicole B, Simon, Carol A
- Authors: van Rensburg, Hendre , Richoux, Nicole B , Simon, Carol A
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454404 , vital:75341 , xlink:href="https://doi.org/10.1016/j.ecss.2023.108549"
- Description: The Knysna Estuary is a large, clear-water embayment and one of the most important estuaries for conservation in southern Africa. The estuary is detritus-dominated and the benthic food webs have low diversities of carnivores, which may make the estuary vulnerable to invasions through the empty niche hypothesis. In the last two decades, the Knysna Estuary has experienced an increase in the population of the cryptogenic and apparently omnivorous estuarine moonshine worm (Diopatra aciculata). Our goal was to describe the trophic role of D. aciculata. We measured carbon and nitrogen stable isotopes in all the common macrophytes and macroinvertebrates across four seasons to 1) establish the isotopic landscapes of three disparate sites within the Knysna Estuary where D. aciculata occurs, 2) establish whether the trophic level of D. aciculata matches those of other common macroinvertebrates, and 3) establish whether the isotopic niche of D. aciculata overlaps with those of syntopic macroinvertebrates. Communities at the different sites differed in food web width, most likely due to differences in primary producer diversity. Our findings suggested that D. aciculata is a facultative carnivore, and some sub-populations are sustained primarily by animal tissues. Isotopic niche overlap analysis showed that direct competition with other common macroinvertebrate consumers is doubtful and D. aciculata occupies a unique niche within the estuary.
- Full Text:
- Date Issued: 2023
- Authors: van Rensburg, Hendre , Richoux, Nicole B , Simon, Carol A
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454404 , vital:75341 , xlink:href="https://doi.org/10.1016/j.ecss.2023.108549"
- Description: The Knysna Estuary is a large, clear-water embayment and one of the most important estuaries for conservation in southern Africa. The estuary is detritus-dominated and the benthic food webs have low diversities of carnivores, which may make the estuary vulnerable to invasions through the empty niche hypothesis. In the last two decades, the Knysna Estuary has experienced an increase in the population of the cryptogenic and apparently omnivorous estuarine moonshine worm (Diopatra aciculata). Our goal was to describe the trophic role of D. aciculata. We measured carbon and nitrogen stable isotopes in all the common macrophytes and macroinvertebrates across four seasons to 1) establish the isotopic landscapes of three disparate sites within the Knysna Estuary where D. aciculata occurs, 2) establish whether the trophic level of D. aciculata matches those of other common macroinvertebrates, and 3) establish whether the isotopic niche of D. aciculata overlaps with those of syntopic macroinvertebrates. Communities at the different sites differed in food web width, most likely due to differences in primary producer diversity. Our findings suggested that D. aciculata is a facultative carnivore, and some sub-populations are sustained primarily by animal tissues. Isotopic niche overlap analysis showed that direct competition with other common macroinvertebrate consumers is doubtful and D. aciculata occupies a unique niche within the estuary.
- Full Text:
- Date Issued: 2023
The use of a Subjective wellbeing scale as predictor of adherence to neuroleptic treatment to determine poor prognostic factor in African population with Schizophrenia
- Boshe, J J, Stein, Dan J, Campbell, Megan M
- Authors: Boshe, J J , Stein, Dan J , Campbell, Megan M
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450766 , vital:74980 , xlink:href="10.1192/j.eurpsy.2023.384"
- Description: Objectives: To investigate and identify demographic and clinical predic-tors of subjective well-being in a sample of Xhosa people with schizo-phrenia on neuroleptic treatment. Methods: As a part of a large genetic study, 244 study participants with a confirmed diagnosis of schizophre-nia completed the translated SWN-K 20 scale. Internal consistency analysis was performed, and convergent analysis and exploratory analysis were conducted using Principal Component Analysis (PCA). Linear regression methods were used to determine predictors of SWBN in the sample population.
- Full Text:
- Date Issued: 2023
- Authors: Boshe, J J , Stein, Dan J , Campbell, Megan M
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450766 , vital:74980 , xlink:href="10.1192/j.eurpsy.2023.384"
- Description: Objectives: To investigate and identify demographic and clinical predic-tors of subjective well-being in a sample of Xhosa people with schizo-phrenia on neuroleptic treatment. Methods: As a part of a large genetic study, 244 study participants with a confirmed diagnosis of schizophre-nia completed the translated SWN-K 20 scale. Internal consistency analysis was performed, and convergent analysis and exploratory analysis were conducted using Principal Component Analysis (PCA). Linear regression methods were used to determine predictors of SWBN in the sample population.
- Full Text:
- Date Issued: 2023
Transboundary Fisheries Management in Kavango–Zambezi Transfrontier Conservation Area (KAZA-TFCA): Prospects and Dilemmas
- Imbwae, Imikendu, Aswani, Shankar, Sauer, Warwick H H, Hay, Clinton J
- Authors: Imbwae, Imikendu , Aswani, Shankar , Sauer, Warwick H H , Hay, Clinton J
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391433 , vital:68651 , xlink:href="https://doi.org/10.3390/su15054406"
- Description: Inland fisheries in the Kavango–Zambezi Transfrontier Conservation Area (KAZA-TFCA) offer food security to the riverine communities across the region. They also contribute towards the attainment of the United Nations’ Sustainable Development Goals 1 and 15, which aim to alleviate poverty and maintain biodiversity conservation. Despite this significant role, the fisheries have suffered severe declines in the previous decades due to multiple factors, such as overfishing and poor legislation. Furthermore, climate change is exerting pressure by altering the ecology and productivity of the river systems. The unprecedented challenges of the COVID-19 pandemic have further constrained management efforts. Attempts to address these challenges have pointed towards transboundary fisheries management as a silver bullet in moving towards sustainable fisheries management. However, the implementation of this strategy in the region has encountered numerous roadblocks, thereby subjecting the river ecosystem to a wider environmental threat, with dire consequences on livelihoods. This paper reviews existing management and governance structures together with key informant interviews to elicit primary and secondary data essential for management at the regional level. The study identifies conflicting regulations, and inadequate policies and institutions across the region as major bottlenecks affecting the successful implementation of transboundary fisheries management. Finally, the paper offers some suggestions for the improvement of fisheries management in the region.
- Full Text:
- Date Issued: 2023
- Authors: Imbwae, Imikendu , Aswani, Shankar , Sauer, Warwick H H , Hay, Clinton J
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391433 , vital:68651 , xlink:href="https://doi.org/10.3390/su15054406"
- Description: Inland fisheries in the Kavango–Zambezi Transfrontier Conservation Area (KAZA-TFCA) offer food security to the riverine communities across the region. They also contribute towards the attainment of the United Nations’ Sustainable Development Goals 1 and 15, which aim to alleviate poverty and maintain biodiversity conservation. Despite this significant role, the fisheries have suffered severe declines in the previous decades due to multiple factors, such as overfishing and poor legislation. Furthermore, climate change is exerting pressure by altering the ecology and productivity of the river systems. The unprecedented challenges of the COVID-19 pandemic have further constrained management efforts. Attempts to address these challenges have pointed towards transboundary fisheries management as a silver bullet in moving towards sustainable fisheries management. However, the implementation of this strategy in the region has encountered numerous roadblocks, thereby subjecting the river ecosystem to a wider environmental threat, with dire consequences on livelihoods. This paper reviews existing management and governance structures together with key informant interviews to elicit primary and secondary data essential for management at the regional level. The study identifies conflicting regulations, and inadequate policies and institutions across the region as major bottlenecks affecting the successful implementation of transboundary fisheries management. Finally, the paper offers some suggestions for the improvement of fisheries management in the region.
- Full Text:
- Date Issued: 2023
Trauma survivors’ perceptions and experiences of prolonged exposure for PTSD at a psychology clinic
- Booysen, Duane D, Kagee, Ashraf
- Authors: Booysen, Duane D , Kagee, Ashraf
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454177 , vital:75316 , xlink:href="https://hdl.handle.net/10520/ejc-m_sajp_v29_n1_a1869"
- Description: BACKGROUND Several trauma-focused treatments have been developed to treat post-traumatic stress disorder (PTSD). Yet there are limited studies on how trauma survivors perceive and experience trauma-focused treatments such as prolonged exposure therapy (PE) for PTSD, especially in low- and middle-income countries (LMIC). AIM The study aimed to explore the perceptions and experiences of trauma survivors receiving prolonged exposure therapy for PTSD and the general acceptability of PE for PTSD in a LMIC.
- Full Text:
- Date Issued: 2023
- Authors: Booysen, Duane D , Kagee, Ashraf
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454177 , vital:75316 , xlink:href="https://hdl.handle.net/10520/ejc-m_sajp_v29_n1_a1869"
- Description: BACKGROUND Several trauma-focused treatments have been developed to treat post-traumatic stress disorder (PTSD). Yet there are limited studies on how trauma survivors perceive and experience trauma-focused treatments such as prolonged exposure therapy (PE) for PTSD, especially in low- and middle-income countries (LMIC). AIM The study aimed to explore the perceptions and experiences of trauma survivors receiving prolonged exposure therapy for PTSD and the general acceptability of PE for PTSD in a LMIC.
- Full Text:
- Date Issued: 2023
TVET SI: Evaluating Boundary Crossing Social Learning in Vocational Education and Training: A value creation approach
- Lotz-Sisitka, Heila, Sisitka, Lawrence, Chakona, Gamuchirai, Matiwane, Mandilive L, Matambo, Chamu
- Authors: Lotz-Sisitka, Heila , Sisitka, Lawrence , Chakona, Gamuchirai , Matiwane, Mandilive L , Matambo, Chamu
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389925 , vital:68495 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/238540"
- Description: This article focuses on the development and application of an evaluation model and approach for evaluating boundary crossing social learning in a Vocational Education and Training (VET) learning network in South Africa, with an emphasis on a Training of Trainers (ToT) course that helped to catalyse and strengthen this learning network via two iterations of the course over an eight-year period. The article shares how we adapted the value creation framework (VCF) of Wenger, Traynor and De Laat (2011; Wenger and Wenger-Traynor, 2020) in the evaluation of a VET Training of Trainers (ToT) programme and learning network that focussed on the uptake and circulation of rainwater harvesting and conservation (RWHandC) knowledge in a particular formal and informal VET context in the Eastern Cape, South Africa, where smallholder farmers were struggling to find water for producing food. The evaluated ToT course was catalytic in establishing a boundary crossing social learning network approach in a VET context that linked formal and informal VET (Lotz-Sisitka et al., 2016; Lotz-Sisitka et al., 2022; Pesanayi, 2019); hence we found it important to develop adequate tools for its evaluation. The focus of this article is to share how we developed an evaluation approach to this work. We share insights on the indicators developed for diff erent types of value created, and also insights gained into the use of this evaluation approach in a boundary crossing VET social learning project that took a ToT course as focus. In short, evaluation findings show that the boundary crossing ToT course off ers strong immediate, potential and applied value that can lead to realised and reframed value, especially if supported by ongoing learning network activities that follow the initial engagement in the boundary crossing ToT course. Th is leads, over time, to transformative value which is important in achieving the overall objective of such social learning, namely making knowledge more co-engaging, accessible and useful in the context where improved food security via better use of rainwater harvesting and conservation amongst smallholder farmers and household food producers is a necessary form of sustainable development. Orientation value, and enabling value were found to be vital for the emergence of other kinds of value. The evaluation model also allows for the lifting out of strategic value which points to wider uptake potential. All this creates the possibility for indicator development that can help inform iterative development of boundary crossing VET courses used to stimulate the co-construction of learning networks and ongoing social learning for sustainable development.
- Full Text:
- Date Issued: 2023
- Authors: Lotz-Sisitka, Heila , Sisitka, Lawrence , Chakona, Gamuchirai , Matiwane, Mandilive L , Matambo, Chamu
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389925 , vital:68495 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/238540"
- Description: This article focuses on the development and application of an evaluation model and approach for evaluating boundary crossing social learning in a Vocational Education and Training (VET) learning network in South Africa, with an emphasis on a Training of Trainers (ToT) course that helped to catalyse and strengthen this learning network via two iterations of the course over an eight-year period. The article shares how we adapted the value creation framework (VCF) of Wenger, Traynor and De Laat (2011; Wenger and Wenger-Traynor, 2020) in the evaluation of a VET Training of Trainers (ToT) programme and learning network that focussed on the uptake and circulation of rainwater harvesting and conservation (RWHandC) knowledge in a particular formal and informal VET context in the Eastern Cape, South Africa, where smallholder farmers were struggling to find water for producing food. The evaluated ToT course was catalytic in establishing a boundary crossing social learning network approach in a VET context that linked formal and informal VET (Lotz-Sisitka et al., 2016; Lotz-Sisitka et al., 2022; Pesanayi, 2019); hence we found it important to develop adequate tools for its evaluation. The focus of this article is to share how we developed an evaluation approach to this work. We share insights on the indicators developed for diff erent types of value created, and also insights gained into the use of this evaluation approach in a boundary crossing VET social learning project that took a ToT course as focus. In short, evaluation findings show that the boundary crossing ToT course off ers strong immediate, potential and applied value that can lead to realised and reframed value, especially if supported by ongoing learning network activities that follow the initial engagement in the boundary crossing ToT course. Th is leads, over time, to transformative value which is important in achieving the overall objective of such social learning, namely making knowledge more co-engaging, accessible and useful in the context where improved food security via better use of rainwater harvesting and conservation amongst smallholder farmers and household food producers is a necessary form of sustainable development. Orientation value, and enabling value were found to be vital for the emergence of other kinds of value. The evaluation model also allows for the lifting out of strategic value which points to wider uptake potential. All this creates the possibility for indicator development that can help inform iterative development of boundary crossing VET courses used to stimulate the co-construction of learning networks and ongoing social learning for sustainable development.
- Full Text:
- Date Issued: 2023
Understanding foraging practices in Lagos metropolis to redesign urban greenspaces in support of human-nature interactions
- Adeyemi, Opeyemi, Shackleton, Charlie M
- Authors: Adeyemi, Opeyemi , Shackleton, Charlie M
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/401353 , vital:69728 , xlink:href="https://doi.org/10.1016/j.ufug.2022.127805"
- Description: Enhancing knowledge of urban foraging across different urban landscapes is an urgent matter given that about two-thirds of the world’s population is projected to live in urban areas by 2050, whilst 50 % of Africa’s population is expected to live in cities by 2030. This study was conducted in Lagos metropolis which is the economic hub of Africa’s most populous country. Data was collected using an in-person, semi-structured questionnaire from 347 persons who were 18 years or older to identify foragers and non-foragers, their sociodemographic profiles, and their foraging practices. Results revealed that about two out of three persons sampled forage to some degree. The collection happened more in domestic gardens (34 %) and streets (27 %) than in other foraging sites (such as unused lands, institutional grounds and lakes and riparian fringes). A total of 35 species were reportedly foraged within the metropolis, mostly for food (71 %) and medicine (26 %). Mango (Mangifera indica), pawpaw (Carica papaya), tropical almond (Terminalia catappa), fish (various species), bitter leaf (Vernonia amygdalina) and spinach (Spinacia oleracea) were the most gathered species. The distance travelled to foraging wild species ranged from 5 m to 25 km. The primary motivation for foraging was the acquisition of fresh and natural materials. However, some felt that foraging was a stressful activity. The unavailability of foraging sites and species was the major constraint to foraging in this megacity. Hence, efforts to increase the edible components of public green spaces and to provide free access could potentially allow more people to forage and make current foraging more secure. We suggest that making provisions for foraging in urban planning goals could contribute to the sustainable development of cities in Africa and elsewhere.
- Full Text:
- Date Issued: 2023
- Authors: Adeyemi, Opeyemi , Shackleton, Charlie M
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/401353 , vital:69728 , xlink:href="https://doi.org/10.1016/j.ufug.2022.127805"
- Description: Enhancing knowledge of urban foraging across different urban landscapes is an urgent matter given that about two-thirds of the world’s population is projected to live in urban areas by 2050, whilst 50 % of Africa’s population is expected to live in cities by 2030. This study was conducted in Lagos metropolis which is the economic hub of Africa’s most populous country. Data was collected using an in-person, semi-structured questionnaire from 347 persons who were 18 years or older to identify foragers and non-foragers, their sociodemographic profiles, and their foraging practices. Results revealed that about two out of three persons sampled forage to some degree. The collection happened more in domestic gardens (34 %) and streets (27 %) than in other foraging sites (such as unused lands, institutional grounds and lakes and riparian fringes). A total of 35 species were reportedly foraged within the metropolis, mostly for food (71 %) and medicine (26 %). Mango (Mangifera indica), pawpaw (Carica papaya), tropical almond (Terminalia catappa), fish (various species), bitter leaf (Vernonia amygdalina) and spinach (Spinacia oleracea) were the most gathered species. The distance travelled to foraging wild species ranged from 5 m to 25 km. The primary motivation for foraging was the acquisition of fresh and natural materials. However, some felt that foraging was a stressful activity. The unavailability of foraging sites and species was the major constraint to foraging in this megacity. Hence, efforts to increase the edible components of public green spaces and to provide free access could potentially allow more people to forage and make current foraging more secure. We suggest that making provisions for foraging in urban planning goals could contribute to the sustainable development of cities in Africa and elsewhere.
- Full Text:
- Date Issued: 2023
Unveiling the reactivity of truxillic and truxinic acids (TXAs): deprotonation, anion center dot center dot center dot HO, cation center dot center dot center dot O and cation center dot center dot center dot pi interactions in TXA (0) center dot center dot center dot Y+ and TXA (0) center dot center dot center dot Z (-) complexes (Y= Li, Na, K; Z= F, Cl, Br)
- Isamura, Bienfait K, Patouossa, Issofa, Muya, Jules T, Lobb, Kevin A
- Authors: Isamura, Bienfait K , Patouossa, Issofa , Muya, Jules T , Lobb, Kevin A
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452827 , vital:75173 , xlink:href="https://link.springer.com/content/pdf/10.1007/s11224-022-01965-5.pdf"
- Description: Herein, we report a quantum chemistry investigation of the interaction between µ-truxinic acid, referred to as TXA0 , and Y+ (Y=Li, Na, K) and Z− (Z=F, Cl, Br) ions using M06-2X, B3LYP and 휔 B97XD functionals in conjunction with the 6–31+ +G(d,p), aug-cc-pVDZ(-X2C) and 6–311+ +G (d, p) basis sets. Our computations suggest that Y+ cations can bind to TXA0 through several combinations of cation…O and cation-π interactions, while Z− anions generally establish anion… H–O contacts. Predicted binding energies at the M06-2X/6–311+ +G(d,p) level range between−26.6 and−70.2 kcal/mol for cationic complexes and−20.4 and−62.3 kcal/mol for anionic ones. As such, TXA0 appears as an amphoteric molecule with a slight preference for electrophilic (cation... O) attacks. Furthermore, the most favourable binding site for cations allows for the formation of O…cation…O interactions where the cation is trapped between O37 and O38 atoms of TXA0 . Anions do not behave uniformly towards TXA0 : while the fuoride anion F− induces the deprotonation of TXA0 , Br− and Cl− do not. All of these structural insights are supported by topological calculations in the context of the quantum theory of atoms in molecules (QTAIM). Finally, SAPT0 analyses suggest that TXA0 …Y+ and TXA0 …Z− complexes are mainly stabilized by electrostatic and inductive efects, whose combined contributions account for more than 60 percent of the total interaction energy.
- Full Text:
- Date Issued: 2023
- Authors: Isamura, Bienfait K , Patouossa, Issofa , Muya, Jules T , Lobb, Kevin A
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452827 , vital:75173 , xlink:href="https://link.springer.com/content/pdf/10.1007/s11224-022-01965-5.pdf"
- Description: Herein, we report a quantum chemistry investigation of the interaction between µ-truxinic acid, referred to as TXA0 , and Y+ (Y=Li, Na, K) and Z− (Z=F, Cl, Br) ions using M06-2X, B3LYP and 휔 B97XD functionals in conjunction with the 6–31+ +G(d,p), aug-cc-pVDZ(-X2C) and 6–311+ +G (d, p) basis sets. Our computations suggest that Y+ cations can bind to TXA0 through several combinations of cation…O and cation-π interactions, while Z− anions generally establish anion… H–O contacts. Predicted binding energies at the M06-2X/6–311+ +G(d,p) level range between−26.6 and−70.2 kcal/mol for cationic complexes and−20.4 and−62.3 kcal/mol for anionic ones. As such, TXA0 appears as an amphoteric molecule with a slight preference for electrophilic (cation... O) attacks. Furthermore, the most favourable binding site for cations allows for the formation of O…cation…O interactions where the cation is trapped between O37 and O38 atoms of TXA0 . Anions do not behave uniformly towards TXA0 : while the fuoride anion F− induces the deprotonation of TXA0 , Br− and Cl− do not. All of these structural insights are supported by topological calculations in the context of the quantum theory of atoms in molecules (QTAIM). Finally, SAPT0 analyses suggest that TXA0 …Y+ and TXA0 …Z− complexes are mainly stabilized by electrostatic and inductive efects, whose combined contributions account for more than 60 percent of the total interaction energy.
- Full Text:
- Date Issued: 2023
Using Facebook user photos to quantify surface water dependency in Southern African arid-zone bird species
- Dixon, Elizabeth A, Smit, Ben
- Authors: Dixon, Elizabeth A , Smit, Ben
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441668 , vital:73905 , https://doi.org/10.1080/01584197.2023.2182223
- Description: Birds need to maintain their hydration by either gaining water from their food or by drinking surface water. Many arid-zone birds do not need to consume surface water to maintain body condition. Conservationists need to better understand avian use of surface water sources to inform management plans in a warming world. In this study, we explored the use of Facebook’s image search as a tool to predict interspecific variations in avian surface water use. There was a significant correlation between the proportion of Facebook photographs of each species associated with surface water, and surface water use indices for these species based on published field studies. These findings suggest that Facebook may be a useful source of data for determining the dependence of bird species on surface water. Future research could address the potential for Facebook and other social media platforms for answering a range of ecological questions relating to avian water dependency.
- Full Text:
- Date Issued: 2023
- Authors: Dixon, Elizabeth A , Smit, Ben
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441668 , vital:73905 , https://doi.org/10.1080/01584197.2023.2182223
- Description: Birds need to maintain their hydration by either gaining water from their food or by drinking surface water. Many arid-zone birds do not need to consume surface water to maintain body condition. Conservationists need to better understand avian use of surface water sources to inform management plans in a warming world. In this study, we explored the use of Facebook’s image search as a tool to predict interspecific variations in avian surface water use. There was a significant correlation between the proportion of Facebook photographs of each species associated with surface water, and surface water use indices for these species based on published field studies. These findings suggest that Facebook may be a useful source of data for determining the dependence of bird species on surface water. Future research could address the potential for Facebook and other social media platforms for answering a range of ecological questions relating to avian water dependency.
- Full Text:
- Date Issued: 2023
Wing-moult and seasonal occurrence of sunbirds (Nectariniidae) captured at four sites in the Eastern Cape, South Africa
- Bonnevie, Bo T, Craig, Adrian J F K, Hulley, Patrick E, Schultz, Albert, Tree, Anthony J
- Authors: Bonnevie, Bo T , Craig, Adrian J F K , Hulley, Patrick E , Schultz, Albert , Tree, Anthony J
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449607 , vital:74833 , https://doi.org/10.2989/00306525.2022.2075482
- Description: Ringing activity in the Eastern Cape province, South Africa, spanned 30 years, with three sites active concurrently over a 14-year period, and three sites over a 6-year period. In total, in the course of 714 ringing days, in all months, we handled 1 207 Amethyst Sunbirds, 708 Southern Double-collared Sunbirds, 707 Greater Double-collared Sunbirds, 381 Grey Sunbirds, 121 Malachite Sunbirds and 140 Collared Sunbirds. Although individuals of all six species were recaptured more than five years after ringing, and despite evidence of the seasonal passage of sunbirds at two sites near the Indian Ocean coast, no birds were recaptured away from the original ringing site.
- Full Text:
- Date Issued: 2023
- Authors: Bonnevie, Bo T , Craig, Adrian J F K , Hulley, Patrick E , Schultz, Albert , Tree, Anthony J
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449607 , vital:74833 , https://doi.org/10.2989/00306525.2022.2075482
- Description: Ringing activity in the Eastern Cape province, South Africa, spanned 30 years, with three sites active concurrently over a 14-year period, and three sites over a 6-year period. In total, in the course of 714 ringing days, in all months, we handled 1 207 Amethyst Sunbirds, 708 Southern Double-collared Sunbirds, 707 Greater Double-collared Sunbirds, 381 Grey Sunbirds, 121 Malachite Sunbirds and 140 Collared Sunbirds. Although individuals of all six species were recaptured more than five years after ringing, and despite evidence of the seasonal passage of sunbirds at two sites near the Indian Ocean coast, no birds were recaptured away from the original ringing site.
- Full Text:
- Date Issued: 2023
Women farmers leading and co-learning in an agroecology movement at the intersections of gender and climate
- Chanyau, Ludwig, Rosenberg, Eureta
- Authors: Chanyau, Ludwig , Rosenberg, Eureta
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373873 , vital:66730 , xlink:href="https://doi.org/10.1080/10130950.2023.2239313"
- Description: This study, carried out in the Eastern Cape Province of South Africa, was particularly interested in women farmers’ access to social learning spaces for expanding their knowledge about farming in the context of climate change. Small-scale women and peasant farmers face historical intersectional inequalities as a result of the colonial and apartheid past which has continued to disadvantage women in the present through exclusion, limited or no access to finance, insecure or no land tenure, little bargaining power and unequal access to water. The gender prejudices and unequal access to resources experienced by women is brought into sharp relief by climate change. The article provides a case study of an agroecology movement led by women farmers that promotes climate-appropriate, low-cost farming practices using community and home gardens. The practices are tried out and further developed by women farmers themselves, relying on agroecology-informed extension services, open dialogue and the support of communities of practice. Unlike traditional top-down approaches to farmer learning common in public extension services, extension officers in the movement participate in creating conditions for co-learning and co-construction of new knowledge − that is, social learning − thus responding directly to their needs as farmers. The lead researcher joined in and observed farming and learning activities following an ethnographic approach. Farmers and other movement members were engaged in semi-structured interviews which explored the value derived from social learning (Wenger-Trayner and Wenger-Trayner Citation2020). The article concludes that the movement is responding to many of the intersectional challenges that women farmers in the Eastern Cape face. Further, its social learning approach holds potential for expanding women farmers’ ability to provide for themselves and their communities and inform their climate change adaptation.
- Full Text:
- Date Issued: 2023
- Authors: Chanyau, Ludwig , Rosenberg, Eureta
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373873 , vital:66730 , xlink:href="https://doi.org/10.1080/10130950.2023.2239313"
- Description: This study, carried out in the Eastern Cape Province of South Africa, was particularly interested in women farmers’ access to social learning spaces for expanding their knowledge about farming in the context of climate change. Small-scale women and peasant farmers face historical intersectional inequalities as a result of the colonial and apartheid past which has continued to disadvantage women in the present through exclusion, limited or no access to finance, insecure or no land tenure, little bargaining power and unequal access to water. The gender prejudices and unequal access to resources experienced by women is brought into sharp relief by climate change. The article provides a case study of an agroecology movement led by women farmers that promotes climate-appropriate, low-cost farming practices using community and home gardens. The practices are tried out and further developed by women farmers themselves, relying on agroecology-informed extension services, open dialogue and the support of communities of practice. Unlike traditional top-down approaches to farmer learning common in public extension services, extension officers in the movement participate in creating conditions for co-learning and co-construction of new knowledge − that is, social learning − thus responding directly to their needs as farmers. The lead researcher joined in and observed farming and learning activities following an ethnographic approach. Farmers and other movement members were engaged in semi-structured interviews which explored the value derived from social learning (Wenger-Trayner and Wenger-Trayner Citation2020). The article concludes that the movement is responding to many of the intersectional challenges that women farmers in the Eastern Cape face. Further, its social learning approach holds potential for expanding women farmers’ ability to provide for themselves and their communities and inform their climate change adaptation.
- Full Text:
- Date Issued: 2023
“A Sort of Arcadian Country”: Plant-Life in Some Early South African Travelogues
- Authors: Wylie, Dan
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/458061 , vital:75713 , https://hdl.handle.net/10520/ejc-iseaeng_v50_n1_a1
- Description: Various branches of current ecocriticism are exploring ways of dismantling or at least diminishing dominant anthropocentric ways of evaluating the relationships among humans, the non-human world, and the literary imagination. Critical Animal Studies, Critical Plant Studies, and multispecies ecocriticism endeavour to re-evaluate the roles, even agency, of non-human life, as represented in literary works. This article unpacks the depiction of plants in three early South African travelogues (1795–1836), illuminating the sources of some enduring assumptions and iconic imageries in our relations with the natural world.
- Full Text:
- Date Issued: 2023
- Authors: Wylie, Dan
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/458061 , vital:75713 , https://hdl.handle.net/10520/ejc-iseaeng_v50_n1_a1
- Description: Various branches of current ecocriticism are exploring ways of dismantling or at least diminishing dominant anthropocentric ways of evaluating the relationships among humans, the non-human world, and the literary imagination. Critical Animal Studies, Critical Plant Studies, and multispecies ecocriticism endeavour to re-evaluate the roles, even agency, of non-human life, as represented in literary works. This article unpacks the depiction of plants in three early South African travelogues (1795–1836), illuminating the sources of some enduring assumptions and iconic imageries in our relations with the natural world.
- Full Text:
- Date Issued: 2023
A Change Project story: learning and caring for South Africa’s rivers
- Authors: Chetty, Preven
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391060 , vital:68613 , xlink:href="https://eeasa.org.za/wp-content/uploads/2023/02/Final-EEASA-Bulletin-20212022-Final.pdf"
- Description: Water quality and scarcity is a major concern in Southern Africa and globally especially as the threat of climate change looms even closer. The current drought in South Africa and worsening rainfall has exposed the brittle nature of this country’s resilience to water shortages. Compounded to this is the fact that most rivers in South Africa are not adequately cared for and are under tremendous strain. Everyone who depends on these rivers whether directly or indirectly will soon be entering a new era where water will no longer be a ubiquitous commodity.
- Full Text:
- Date Issued: 2022
- Authors: Chetty, Preven
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391060 , vital:68613 , xlink:href="https://eeasa.org.za/wp-content/uploads/2023/02/Final-EEASA-Bulletin-20212022-Final.pdf"
- Description: Water quality and scarcity is a major concern in Southern Africa and globally especially as the threat of climate change looms even closer. The current drought in South Africa and worsening rainfall has exposed the brittle nature of this country’s resilience to water shortages. Compounded to this is the fact that most rivers in South Africa are not adequately cared for and are under tremendous strain. Everyone who depends on these rivers whether directly or indirectly will soon be entering a new era where water will no longer be a ubiquitous commodity.
- Full Text:
- Date Issued: 2022
A laminated, emergentist view of skills ecosystems
- Ramsarup, Presha, Lotz-Sisitka, Heila, McGrath, Simon
- Authors: Ramsarup, Presha , Lotz-Sisitka, Heila , McGrath, Simon
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370074 , vital:66295 , xlink:href="https://doi.org/10.1080/14767430.2022.2145768"
- Description: In this paper we present a model of vocational education and training (VET) that can be used to guide decisions relating to VET in Africa today. This model takes the critique of the neoclassical, neoliberal model of VET as its starting point. Guided by Bhaskar's Critical Naturalism, we use immanent critique to consider the adequacy of proposed alternatives to the neoclassical approach, such as: the heterodox approach, which foregrounds explanations based on human capital and political economy; and Hodgson and Spours' social ecosystem model, which addresses some of the limitations of the heterodox account by including, social and ecosystem elements. Finally, we offer a version of the social ecosystem model that, according to our analysis, explains more of the empirical evidence than previous models. Our version of the social ecosystem model differs from earlier versions in terms of its explicit reference to the critical realist ideas of position- practices and emergence.
- Full Text:
- Date Issued: 2022
- Authors: Ramsarup, Presha , Lotz-Sisitka, Heila , McGrath, Simon
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370074 , vital:66295 , xlink:href="https://doi.org/10.1080/14767430.2022.2145768"
- Description: In this paper we present a model of vocational education and training (VET) that can be used to guide decisions relating to VET in Africa today. This model takes the critique of the neoclassical, neoliberal model of VET as its starting point. Guided by Bhaskar's Critical Naturalism, we use immanent critique to consider the adequacy of proposed alternatives to the neoclassical approach, such as: the heterodox approach, which foregrounds explanations based on human capital and political economy; and Hodgson and Spours' social ecosystem model, which addresses some of the limitations of the heterodox account by including, social and ecosystem elements. Finally, we offer a version of the social ecosystem model that, according to our analysis, explains more of the empirical evidence than previous models. Our version of the social ecosystem model differs from earlier versions in terms of its explicit reference to the critical realist ideas of position- practices and emergence.
- Full Text:
- Date Issued: 2022
A multiscale ONIOM study of the buckminsterfullerene (C60) Diels–Alder reaction: from model design to reaction path analysis
- Isamura, Bienfait K, Lobb, Kevin A
- Authors: Isamura, Bienfait K , Lobb, Kevin A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452517 , vital:75140 , xlink:href=" https://link.springer.com/article/10.1007/s00894-022-05319-0"
- Description: The hybrid ONIOM (Our own N-layered Integrated molecular Orbital and molecular Mechanics) formalism is employed to investigate the Diels–Alder reaction of the buckminsterfullerene C60. Our computa-tions suggest that the ONIOM2(M06-2X/6-31G(d): SVWN/STO3G) mod-el, enclosing both the diene and the pyracyclene fragment of C60 in the higher-layer, provides a reasonable trade-of between accuracy and computational cost as it comes to predicting reaction energetics. Moreover, the frontier molecular orbital (FMO) theory and activation strain model (ASM) are jointly relied on to rationalize the efect of –OH and –CN substituents on the activation barrier of this reaction. Finally, reaction paths are scrutinized to get insight into the various forces un-derpinning the process of cycloadduct formation.
- Full Text:
- Date Issued: 2022
- Authors: Isamura, Bienfait K , Lobb, Kevin A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452517 , vital:75140 , xlink:href=" https://link.springer.com/article/10.1007/s00894-022-05319-0"
- Description: The hybrid ONIOM (Our own N-layered Integrated molecular Orbital and molecular Mechanics) formalism is employed to investigate the Diels–Alder reaction of the buckminsterfullerene C60. Our computa-tions suggest that the ONIOM2(M06-2X/6-31G(d): SVWN/STO3G) mod-el, enclosing both the diene and the pyracyclene fragment of C60 in the higher-layer, provides a reasonable trade-of between accuracy and computational cost as it comes to predicting reaction energetics. Moreover, the frontier molecular orbital (FMO) theory and activation strain model (ASM) are jointly relied on to rationalize the efect of –OH and –CN substituents on the activation barrier of this reaction. Finally, reaction paths are scrutinized to get insight into the various forces un-derpinning the process of cycloadduct formation.
- Full Text:
- Date Issued: 2022
A simple quinoline-thiophene Schiff base turn-off chemosensor for Hg2+ detection
- Musikavanhu, Brian, Muthusamy, Selvaraj, Zhu, Dongwei, Xue, Zhaoli, Yu, Qian, Chivumba, Choonzo N, Mack, John, Nyokong, Tebello, Wang, Shengjun, Zhao, Long
- Authors: Musikavanhu, Brian , Muthusamy, Selvaraj , Zhu, Dongwei , Xue, Zhaoli , Yu, Qian , Chivumba, Choonzo N , Mack, John , Nyokong, Tebello , Wang, Shengjun , Zhao, Long
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230362 , vital:49771 , xlink:href="https://doi.org/10.1016/j.saa.2021.120338"
- Description: A new Schiff base probe (QT) consisting of 8-aminoquinoline (Q) and thiophene-2-carboxaldehyde (T) moieties has been synthesized. QT undergoes chelation-enhanced fluorescence quenching when exposed to Hg2+ due to coordination by the sulfur and nitrogen atoms of QT thus forming a facile “turn-off” sensor. The formation of the chelation complex was confirmed by UV–visible absorption and emission spectral measurements, 1H NMR titration and density functional theory calculations. These studies revealed that the probe exhibits high selectivity and sensitivity towards Hg2+ in the presence of other common metal ions. A low detection limit of 23.4 nM was determined and a Job plot confirmed a 2:1 stoichiometry between QT and Hg2+. The potential utility of QT as a sensor for Hg2+ ions in human HeLa cells was determined by confocal fluorescence microscopy, and its suitability for use in the field with environmental samples was tested with Whatman filter paper strips.
- Full Text:
- Date Issued: 2022
- Authors: Musikavanhu, Brian , Muthusamy, Selvaraj , Zhu, Dongwei , Xue, Zhaoli , Yu, Qian , Chivumba, Choonzo N , Mack, John , Nyokong, Tebello , Wang, Shengjun , Zhao, Long
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230362 , vital:49771 , xlink:href="https://doi.org/10.1016/j.saa.2021.120338"
- Description: A new Schiff base probe (QT) consisting of 8-aminoquinoline (Q) and thiophene-2-carboxaldehyde (T) moieties has been synthesized. QT undergoes chelation-enhanced fluorescence quenching when exposed to Hg2+ due to coordination by the sulfur and nitrogen atoms of QT thus forming a facile “turn-off” sensor. The formation of the chelation complex was confirmed by UV–visible absorption and emission spectral measurements, 1H NMR titration and density functional theory calculations. These studies revealed that the probe exhibits high selectivity and sensitivity towards Hg2+ in the presence of other common metal ions. A low detection limit of 23.4 nM was determined and a Job plot confirmed a 2:1 stoichiometry between QT and Hg2+. The potential utility of QT as a sensor for Hg2+ ions in human HeLa cells was determined by confocal fluorescence microscopy, and its suitability for use in the field with environmental samples was tested with Whatman filter paper strips.
- Full Text:
- Date Issued: 2022
A Sn (iv) porphyrin with mitochondria targeting properties for enhanced photodynamic activity against MCF-7 cells
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230897 , vital:49829 , xlink:href="https://doi.org/10.1039/D2NJ00350C"
- Description: Two readily synthesized Sn(IV) porphyrins (SnP, SnPH) have been prepared with and without the cationic triphenylphosphonium moiety (TPP+), which have high singlet oxygen quantum yields (ca. 0.72) and long triplet state lifetimes. The Sn(IV) porphyrin with a TPP+ moiety (SnPH) exhibits favorable photodynamic activity against MCF-7 cells with IC50 values of 2.9 μM. SnPH exhibits higher cellular uptake than SnP in MCF-7 cells. A Rhodamine 123 (Rh123) assay showed that SnPH targets mitochondria and induces apoptosis by generating reactive oxygen species. The results demonstrate that this structural modification strategy merits further in-depth study.
- Full Text:
- Date Issued: 2022
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230897 , vital:49829 , xlink:href="https://doi.org/10.1039/D2NJ00350C"
- Description: Two readily synthesized Sn(IV) porphyrins (SnP, SnPH) have been prepared with and without the cationic triphenylphosphonium moiety (TPP+), which have high singlet oxygen quantum yields (ca. 0.72) and long triplet state lifetimes. The Sn(IV) porphyrin with a TPP+ moiety (SnPH) exhibits favorable photodynamic activity against MCF-7 cells with IC50 values of 2.9 μM. SnPH exhibits higher cellular uptake than SnP in MCF-7 cells. A Rhodamine 123 (Rh123) assay showed that SnPH targets mitochondria and induces apoptosis by generating reactive oxygen species. The results demonstrate that this structural modification strategy merits further in-depth study.
- Full Text:
- Date Issued: 2022
African birds as army ant followers
- Authors: Craig, Adrian J F K
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448772 , vital:74759 , https://doi.org/10.1007/s10336-022-01987-0
- Description: Ant-following birds have been studied extensively in the Neotropics, but much less information is currently available for the Afrotropics. There are published records of 168 African bird species from 37 families foraging in association with driver ants (Dorylus, sub-family Dorylinae). However, of 52 bird species assessed as regular ant-followers, 38 belong to three families, which are disproportionately represented compared to other large Afrotropical bird families: Muscicapidae (18 spp.), Pycnonotidae (13 spp.) and Turdidae (7 spp.). The extent to which these birds are dependent on ants through their annual cycle is not known. African driver ants forage primarily under shaded, humid conditions by day, and may spend a month or longer underground. Conservation assessments of African forest habitats suggest that both driver ants and ant-following birds may be especially sensitive to the loss of forest cover.
- Full Text:
- Date Issued: 2022
- Authors: Craig, Adrian J F K
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448772 , vital:74759 , https://doi.org/10.1007/s10336-022-01987-0
- Description: Ant-following birds have been studied extensively in the Neotropics, but much less information is currently available for the Afrotropics. There are published records of 168 African bird species from 37 families foraging in association with driver ants (Dorylus, sub-family Dorylinae). However, of 52 bird species assessed as regular ant-followers, 38 belong to three families, which are disproportionately represented compared to other large Afrotropical bird families: Muscicapidae (18 spp.), Pycnonotidae (13 spp.) and Turdidae (7 spp.). The extent to which these birds are dependent on ants through their annual cycle is not known. African driver ants forage primarily under shaded, humid conditions by day, and may spend a month or longer underground. Conservation assessments of African forest habitats suggest that both driver ants and ant-following birds may be especially sensitive to the loss of forest cover.
- Full Text:
- Date Issued: 2022
Age and growth of the Cape knifejaw Oplegnathus conwayi, an endemic South African teleost
- Foster, Ryan M, Childs, Amber-Robyn, Mann, Bruce Q, Potts, Warren M
- Authors: Foster, Ryan M , Childs, Amber-Robyn , Mann, Bruce Q , Potts, Warren M
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443128 , vital:74080 , https://doi.org/10.1080/15627020.2022.2035254
- Description: The South African spearfishery targets a variety of data-deficient species, which are consequently poorly managed. This study aimed to describe the age and growth of one of these species, the Cape knifejaw, Oplegnathus conwayi, which is endemic to the southern and eastern coasts of South Africa. Monthly biological samples were collected through research spearfishing (n = 170) and augmented by recreational spearfishers’ catches (n = 135). The results indicated that the O. conwayi population sex ratio was skewed towards males (1M:0.6F). The length- and age-frequency distributions were similar between sexes. Oplegnathus conwayi is a relatively slow-growing species, with a maximum-recorded age of 27 years. No significant differences were observed between male and female growth, with the overall population growth curve being best described as L(t) = 697.15(1 − e−0.06(t−6.30)). The slow growth observed in this species is characteristic of a species that is vulnerable to overexploitation, and accordingly a precautionary approach to future management is recommended.
- Full Text:
- Date Issued: 2022
- Authors: Foster, Ryan M , Childs, Amber-Robyn , Mann, Bruce Q , Potts, Warren M
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443128 , vital:74080 , https://doi.org/10.1080/15627020.2022.2035254
- Description: The South African spearfishery targets a variety of data-deficient species, which are consequently poorly managed. This study aimed to describe the age and growth of one of these species, the Cape knifejaw, Oplegnathus conwayi, which is endemic to the southern and eastern coasts of South Africa. Monthly biological samples were collected through research spearfishing (n = 170) and augmented by recreational spearfishers’ catches (n = 135). The results indicated that the O. conwayi population sex ratio was skewed towards males (1M:0.6F). The length- and age-frequency distributions were similar between sexes. Oplegnathus conwayi is a relatively slow-growing species, with a maximum-recorded age of 27 years. No significant differences were observed between male and female growth, with the overall population growth curve being best described as L(t) = 697.15(1 − e−0.06(t−6.30)). The slow growth observed in this species is characteristic of a species that is vulnerable to overexploitation, and accordingly a precautionary approach to future management is recommended.
- Full Text:
- Date Issued: 2022
AMADAR: a python-based package for large scale prediction of Diels–Alder transition state geometries and IRC path analysis
- Isamura, Bienfait K, Lobb, Kevin A
- Authors: Isamura, Bienfait K , Lobb, Kevin A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453143 , vital:75226 , xlink:href="https://link.springer.com/article/10.1186/s13321-022-00618-3"
- Description: Predicting transition state geometries is one of the most challenging tasks in computational chemistry, which often requires expert-based knowledge and permanent human intervention. This short communication reports technical details and preliminary results of a python-based tool (AMADAR) designed to generate any Diels–Alder (DA) transition state geometry (TS) and analyze determined IRC paths in a (quasi-)automated fashion, given the product SMILES. Two modules of the package are devoted to performing, from IRC paths, reaction force analyses (RFA) and atomic (fragment) decompositions of the reaction force F and reaction force constant κ. The performance of the protocol has been assessed using a dataset of 2000 DA cycloadducts retrieved from the ZINC database. The sequential location of the corresponding TSs was achieved with a success rate of 95%. RFA plots confrmed the reaction force constant κ to be a good indicator of the (non)synchronicity of the associated DA reactions. Moreover, the atomic decomposition of κ allows for the rationalization of the (a)synchronicity of each DA reaction in terms of contributions stemming from pairs of interacting atoms. The source code of the AMADAR tool is available on GitHub [CMCDD/AMADAR(github. com)] and can be used directly with minor customizations, mostly regarding the local working environment of the user.
- Full Text:
- Date Issued: 2022
- Authors: Isamura, Bienfait K , Lobb, Kevin A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453143 , vital:75226 , xlink:href="https://link.springer.com/article/10.1186/s13321-022-00618-3"
- Description: Predicting transition state geometries is one of the most challenging tasks in computational chemistry, which often requires expert-based knowledge and permanent human intervention. This short communication reports technical details and preliminary results of a python-based tool (AMADAR) designed to generate any Diels–Alder (DA) transition state geometry (TS) and analyze determined IRC paths in a (quasi-)automated fashion, given the product SMILES. Two modules of the package are devoted to performing, from IRC paths, reaction force analyses (RFA) and atomic (fragment) decompositions of the reaction force F and reaction force constant κ. The performance of the protocol has been assessed using a dataset of 2000 DA cycloadducts retrieved from the ZINC database. The sequential location of the corresponding TSs was achieved with a success rate of 95%. RFA plots confrmed the reaction force constant κ to be a good indicator of the (non)synchronicity of the associated DA reactions. Moreover, the atomic decomposition of κ allows for the rationalization of the (a)synchronicity of each DA reaction in terms of contributions stemming from pairs of interacting atoms. The source code of the AMADAR tool is available on GitHub [CMCDD/AMADAR(github. com)] and can be used directly with minor customizations, mostly regarding the local working environment of the user.
- Full Text:
- Date Issued: 2022
Application of gold and palladium nanoparticles supported on polymelamine microspheres in the oxidation of 1-phenylethanol and some other phenyl substituted alcohols
- Storm, Ené, Maggott, Emile D, Mashazi, Philani N, Nyokong, Tebello, Malgas-Enus, Rehana, Mapolie, Selwyn F
- Authors: Storm, Ené , Maggott, Emile D , Mashazi, Philani N , Nyokong, Tebello , Malgas-Enus, Rehana , Mapolie, Selwyn F
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/299824 , vital:57858 , xlink:href="https://doi.org/10.1016/j.mcat.2022.112456"
- Description: Melamine formaldehyde and melamine resorcinol formaldehyde microspheres were decorated with Au and Pd nanoparticles and applied as heterogeneous catalysts in the oxidation of 1-phenylethanol. The catalysts showed similar activities irrespective of the support employed. Moderate conversion activities of 48–50% were achieved when using acetonitrile as solvent; however, when employing water as solvent, the supported catalysts formed a three-phase, emulsion system which facilitated the catalytic conversion of 1-phenylethanol to acetophenone at much higher conversions of around 83%. The oxidant, TBHP, decomposed rapidly in acetonitrile, whilst it remained stable in aqueous solution, leading to the enhanced activities observed when using water as solvent. These systems also proved to be recyclable for up to five cycles, with only slight loss of activity observed; this can be attributed to the physical loss of catalyst during the workup procedure conducted between each cycle.
- Full Text:
- Date Issued: 2022
- Authors: Storm, Ené , Maggott, Emile D , Mashazi, Philani N , Nyokong, Tebello , Malgas-Enus, Rehana , Mapolie, Selwyn F
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/299824 , vital:57858 , xlink:href="https://doi.org/10.1016/j.mcat.2022.112456"
- Description: Melamine formaldehyde and melamine resorcinol formaldehyde microspheres were decorated with Au and Pd nanoparticles and applied as heterogeneous catalysts in the oxidation of 1-phenylethanol. The catalysts showed similar activities irrespective of the support employed. Moderate conversion activities of 48–50% were achieved when using acetonitrile as solvent; however, when employing water as solvent, the supported catalysts formed a three-phase, emulsion system which facilitated the catalytic conversion of 1-phenylethanol to acetophenone at much higher conversions of around 83%. The oxidant, TBHP, decomposed rapidly in acetonitrile, whilst it remained stable in aqueous solution, leading to the enhanced activities observed when using water as solvent. These systems also proved to be recyclable for up to five cycles, with only slight loss of activity observed; this can be attributed to the physical loss of catalyst during the workup procedure conducted between each cycle.
- Full Text:
- Date Issued: 2022