Interactions between two biological control agents and their target weed: a beetle, a bug and a cactus weed
- Mnqeta, Zezethu, Paterson, Iain D
- Authors: Mnqeta, Zezethu , Paterson, Iain D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417475 , vital:71456 , xlink:href="https://doi.org/10.1080/09583157.2019.1631960"
- Description: Pereskia aculeata Miller (Cactaceae) is an invasive alien shrub introduced into South Africa from Brazil. The leaf-feeding beetle, Phenrica guerini Bechyne (Chrysomelidae), was released as a biological control agent in South Africa in 1991 followed by the stem-wilting bug, Catorhintha schaffneri Brailovsky and Garcia (Coreidae), in 2014. This study investigated the interactions between the two agents under laboratory conditions. Potted plants were exposed to one of four treatments: control (no agents), P. guerini only, C. schaffneri only and both species together. Four densities, ranging from 2 to 12 insects per plant were used. Cathorhitha schaffneri alone at low to moderate densities resulted in the same reduction in number of leaves and shoot length as when combine with P. guerini. At the highest density, C. schaffneri reduced the number of leaves significantly more than any treatment. Mortality of P. guerini was significantly higher than C. schaffneri at the highest density when in combination. The antagonistic interaction between P. guerini and C. schaffneri suggests that these agents should not be released together because this would impact negatively on the overall biocontrol programme against P. aculeata. It is recommended that C. schaffneri should be released at sites where P. guerini is not present. Extrapolation of laboratory-based studies into the field is often challenging, so mass-rearing and releases of P. guerini should continue until there is convincing proof that C. schaffneri alone is more effective than P. guerini in the field.
- Full Text:
- Authors: Mnqeta, Zezethu , Paterson, Iain D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417475 , vital:71456 , xlink:href="https://doi.org/10.1080/09583157.2019.1631960"
- Description: Pereskia aculeata Miller (Cactaceae) is an invasive alien shrub introduced into South Africa from Brazil. The leaf-feeding beetle, Phenrica guerini Bechyne (Chrysomelidae), was released as a biological control agent in South Africa in 1991 followed by the stem-wilting bug, Catorhintha schaffneri Brailovsky and Garcia (Coreidae), in 2014. This study investigated the interactions between the two agents under laboratory conditions. Potted plants were exposed to one of four treatments: control (no agents), P. guerini only, C. schaffneri only and both species together. Four densities, ranging from 2 to 12 insects per plant were used. Cathorhitha schaffneri alone at low to moderate densities resulted in the same reduction in number of leaves and shoot length as when combine with P. guerini. At the highest density, C. schaffneri reduced the number of leaves significantly more than any treatment. Mortality of P. guerini was significantly higher than C. schaffneri at the highest density when in combination. The antagonistic interaction between P. guerini and C. schaffneri suggests that these agents should not be released together because this would impact negatively on the overall biocontrol programme against P. aculeata. It is recommended that C. schaffneri should be released at sites where P. guerini is not present. Extrapolation of laboratory-based studies into the field is often challenging, so mass-rearing and releases of P. guerini should continue until there is convincing proof that C. schaffneri alone is more effective than P. guerini in the field.
- Full Text:
Investigation of novel substituted zinc and aluminium phthalocyanines for photodynamic therapy of epithelial breast cancer
- Mohammed, Imadalulla, Oluwole, David O, Nemakal, Majunatha, Sannegowda, Lokesh K, Nyokong, Tebello
- Authors: Mohammed, Imadalulla , Oluwole, David O , Nemakal, Majunatha , Sannegowda, Lokesh K , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186824 , vital:44537 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107592"
- Description: A series of phthalonitrile ligands were synthesized by nucleophilic substitution reaction using the hydroxyl or sulfanyl group precursors and the nitro moiety of the nitrophthalonitrile to yield corresponding oxy or sulfanyl bridged ligands. These ligands were subsequently subjected to cyclocondensation reaction with diamagnetic metal ions like zinc and aluminium to afford symmetrically substituted zinc and aluminium phthalocyanine (Pc) complexes and polymers. The ligands and Pc complexes were characterized by 1 H nuclear magnetic resonance, fourier transform infrared, ultraviolet visible and mass spectrometric techniques. Additionally, thermal gravimetric, and elemental analyzer were used for characterization of the Pc complexes. The photophysical and photochemical behaviour of the Pc complexes were investigated in dimethyl sulfoxide. Additionally, the complexes were tested against epithelial breast cancer cells for photodynamic therapy (PDT) effect. The substituted ZnPc complexes afforded higher singlet oxygen quantum yields as compared to the AlPc analogue. All the complexes showed innocuous invitro dark cytotoxicity and moderate PDT effect.
- Full Text:
- Authors: Mohammed, Imadalulla , Oluwole, David O , Nemakal, Majunatha , Sannegowda, Lokesh K , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186824 , vital:44537 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107592"
- Description: A series of phthalonitrile ligands were synthesized by nucleophilic substitution reaction using the hydroxyl or sulfanyl group precursors and the nitro moiety of the nitrophthalonitrile to yield corresponding oxy or sulfanyl bridged ligands. These ligands were subsequently subjected to cyclocondensation reaction with diamagnetic metal ions like zinc and aluminium to afford symmetrically substituted zinc and aluminium phthalocyanine (Pc) complexes and polymers. The ligands and Pc complexes were characterized by 1 H nuclear magnetic resonance, fourier transform infrared, ultraviolet visible and mass spectrometric techniques. Additionally, thermal gravimetric, and elemental analyzer were used for characterization of the Pc complexes. The photophysical and photochemical behaviour of the Pc complexes were investigated in dimethyl sulfoxide. Additionally, the complexes were tested against epithelial breast cancer cells for photodynamic therapy (PDT) effect. The substituted ZnPc complexes afforded higher singlet oxygen quantum yields as compared to the AlPc analogue. All the complexes showed innocuous invitro dark cytotoxicity and moderate PDT effect.
- Full Text:
Landscape, memory and learning to change in changing worlds: Contemplating intergenerational learning and traditional knowledge practices within social-ecological landscapes of change
- O'Donoghue, Rob B, Sandoval-Rivera, Juan Carlos, Payyappallimana, Unnikrishnan
- Authors: O'Donoghue, Rob B , Sandoval-Rivera, Juan Carlos , Payyappallimana, Unnikrishnan
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/388061 , vital:68304 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/187218"
- Description: The core paper and collection of short papers from Mexico, Africa, India and Sweden that make up this study on social-ecological landscapes developed as a South–South collaboration that was extended to include a case in the North. Our concern was to explore how situated, intergenerational knowledge commonly takes a back seat to the conceptual propositions that the environmental sciences have developed around matters of concern like biodiversity loss. In this way, scientific propositions have become the conceptual capital for informing future sustainability through Education for Sustainable Development (ESD). In response to this, a more situated turn has developed to engage both intergenerational practices and the institutional sciences, but the playing fields are seldom level and deliberations are often rife with misunderstandings.
- Full Text:
- Authors: O'Donoghue, Rob B , Sandoval-Rivera, Juan Carlos , Payyappallimana, Unnikrishnan
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/388061 , vital:68304 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/187218"
- Description: The core paper and collection of short papers from Mexico, Africa, India and Sweden that make up this study on social-ecological landscapes developed as a South–South collaboration that was extended to include a case in the North. Our concern was to explore how situated, intergenerational knowledge commonly takes a back seat to the conceptual propositions that the environmental sciences have developed around matters of concern like biodiversity loss. In this way, scientific propositions have become the conceptual capital for informing future sustainability through Education for Sustainable Development (ESD). In response to this, a more situated turn has developed to engage both intergenerational practices and the institutional sciences, but the playing fields are seldom level and deliberations are often rife with misunderstandings.
- Full Text:
Livelihood benefits and costs from an invasive alien tree (Acacia dealbata) to rural communities in the Eastern Cape, South Africa
- Ngorima, A, Shackleton, Charlie M
- Authors: Ngorima, A , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179755 , vital:43168 , xlink:href="https://doi.org/10.1016/j.jenvman.2018.05.077"
- Description: The negative effects of invasive alien species (IAS) are increasingly invoked to justify widespread and usually top-down approaches for their management or eradication. However, very little of the research or discourse is based on investigating local perceptions, uses and struggles with IAS, and how their presence influences and changes local livelihoods. The objective of this study was to assess the perceptions and livelihood uses of Acacia dealbata by local communities at three localities in the montane grasslands of the Eastern Cape, South Africa, using a combination of random household interviews, focus group discussions and participatory tools. We calculated direct-use values for each product and household (based on quantity used and local prices) and disaggregated these by gender of the household head and wealth quartiles. The results revealed the dualistic role of A. dealbata in local livelihoods. On the one hand, A. dealbata was widely used for firewood (100% of households), tools (77%) and construction timber (73%), with limited use for traditional medicines and forage. The cumulative value of approximately ZAR 2870 (±US$224) per household per year (across all households) represents considerable cash saving to households, most of whom are quite poor by national and international measures. On the other hand, the increasing extent of A. dealbata (93% said it was increasing) exacerbates local household vulnerability though reported reductions in cultivated areas, crop yields and forage production, and allegedly higher risks of crime. This quandary is well encapsulated by the considerable majority of respondents (84%) not wanting higher extents and densities of A. dealbata, but an equally high majority not wanting its total removal from local landscapes. Most respondents disliked A. dealbata in fields, close to homesteads or along primary access routes, and were more tolerant of it away from such sites. Institutional and use dynamics have varied over several decades in response to the changing extent and densities of A. dealbata and the broader political and socio-economic contexts. These results indicate that greater efforts are required to understand perceptions and uses of IAS by the people who live with them, and to direct such understanding into more spatially and temporally contextualised response strategies where required.
- Full Text:
- Authors: Ngorima, A , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179755 , vital:43168 , xlink:href="https://doi.org/10.1016/j.jenvman.2018.05.077"
- Description: The negative effects of invasive alien species (IAS) are increasingly invoked to justify widespread and usually top-down approaches for their management or eradication. However, very little of the research or discourse is based on investigating local perceptions, uses and struggles with IAS, and how their presence influences and changes local livelihoods. The objective of this study was to assess the perceptions and livelihood uses of Acacia dealbata by local communities at three localities in the montane grasslands of the Eastern Cape, South Africa, using a combination of random household interviews, focus group discussions and participatory tools. We calculated direct-use values for each product and household (based on quantity used and local prices) and disaggregated these by gender of the household head and wealth quartiles. The results revealed the dualistic role of A. dealbata in local livelihoods. On the one hand, A. dealbata was widely used for firewood (100% of households), tools (77%) and construction timber (73%), with limited use for traditional medicines and forage. The cumulative value of approximately ZAR 2870 (±US$224) per household per year (across all households) represents considerable cash saving to households, most of whom are quite poor by national and international measures. On the other hand, the increasing extent of A. dealbata (93% said it was increasing) exacerbates local household vulnerability though reported reductions in cultivated areas, crop yields and forage production, and allegedly higher risks of crime. This quandary is well encapsulated by the considerable majority of respondents (84%) not wanting higher extents and densities of A. dealbata, but an equally high majority not wanting its total removal from local landscapes. Most respondents disliked A. dealbata in fields, close to homesteads or along primary access routes, and were more tolerant of it away from such sites. Institutional and use dynamics have varied over several decades in response to the changing extent and densities of A. dealbata and the broader political and socio-economic contexts. These results indicate that greater efforts are required to understand perceptions and uses of IAS by the people who live with them, and to direct such understanding into more spatially and temporally contextualised response strategies where required.
- Full Text:
Magnetic nanoparticle-indium phthalocyanine conjugate embedded in electrospun fiber for photodynamic antimicrobial chemotherapy and photodegradation of methyl red
- Sindelo, Azole, Nyokong, Tebello
- Authors: Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186857 , vital:44540 , xlink:href="https://doi.org/10.1016/j.heliyon.2019.e02352"
- Description: ClIn(III) octacarboxy phthalocyanine (ClInOCPc) when alone or conjugated to magnetic nanoparticles (MNPClInOCPc) was employed for both photodynamic antimicrobial chemotherapy of an unknown water sample and Staphylococcus aureus, and for photo-degradation of methyl red (MR). The singlet oxygen quantum yields (ΦΔ) in water using ClInOCPc and MNP-ClInOCPc embedded in polyacrylonitrile (PAN) electrospun fibers were 0.36 and 0.22, respectively. When in solution, MNP-ClInOCPc gave 90.6% photoinactivation of microbes in a water sample from the stream and of ClInOCPc resulted in 84.8 % photoinactivation. When embedded to the polymer, there was 48.0% clearance for ClInOCPc and 63.7% clearance for MNP-ClInOCPc for the microbes in the water sample from the stream. For the photo-degradation of MR, the rate of degradation increased with decrease of the MR concentration with the MNP-ClInOCPc having the fastest rate.
- Full Text:
- Authors: Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186857 , vital:44540 , xlink:href="https://doi.org/10.1016/j.heliyon.2019.e02352"
- Description: ClIn(III) octacarboxy phthalocyanine (ClInOCPc) when alone or conjugated to magnetic nanoparticles (MNPClInOCPc) was employed for both photodynamic antimicrobial chemotherapy of an unknown water sample and Staphylococcus aureus, and for photo-degradation of methyl red (MR). The singlet oxygen quantum yields (ΦΔ) in water using ClInOCPc and MNP-ClInOCPc embedded in polyacrylonitrile (PAN) electrospun fibers were 0.36 and 0.22, respectively. When in solution, MNP-ClInOCPc gave 90.6% photoinactivation of microbes in a water sample from the stream and of ClInOCPc resulted in 84.8 % photoinactivation. When embedded to the polymer, there was 48.0% clearance for ClInOCPc and 63.7% clearance for MNP-ClInOCPc for the microbes in the water sample from the stream. For the photo-degradation of MR, the rate of degradation increased with decrease of the MR concentration with the MNP-ClInOCPc having the fastest rate.
- Full Text:
Mainstreaming education for sustainable development: Elaborating the role of position-practice systems using seven laminations of scale
- Agbedahin, Adesuwa V, Lotz-Sisitka, Heila
- Authors: Agbedahin, Adesuwa V , Lotz-Sisitka, Heila
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182428 , vital:43829 , xlink:href="https://doi.org/10.1080/14767430.2019.1602975"
- Description: The United Nations Sustainable Development Goal 4.7 proposes that Education for Sustainable Development (ESD) should be included at all levels of education, known as ‘mainstreaming’. However, there is little guidance as to how to achieve this. ESD mainstreaming demands more than simply a technical policy transfer; it also requires attention to the position-practice systems of involved agents. This article critically assesses the mainstreaming of ESD in the case of university educators in Africa who have participated in the International Training Programme on ESD in higher education. It clarifies their position-practice systems in terms of Bhaskar’s seven laminations of scale. This article therefore provides a detailed description of the ways in which agents' position-practice systems enable and constrain ESD mainstreaming. It also demonstrates that a critical realist perspective can contribute towards the understanding and achievement of transformation towards sustainability and can help to ensure the flourishing of both current and future generations.
- Full Text:
- Authors: Agbedahin, Adesuwa V , Lotz-Sisitka, Heila
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182428 , vital:43829 , xlink:href="https://doi.org/10.1080/14767430.2019.1602975"
- Description: The United Nations Sustainable Development Goal 4.7 proposes that Education for Sustainable Development (ESD) should be included at all levels of education, known as ‘mainstreaming’. However, there is little guidance as to how to achieve this. ESD mainstreaming demands more than simply a technical policy transfer; it also requires attention to the position-practice systems of involved agents. This article critically assesses the mainstreaming of ESD in the case of university educators in Africa who have participated in the International Training Programme on ESD in higher education. It clarifies their position-practice systems in terms of Bhaskar’s seven laminations of scale. This article therefore provides a detailed description of the ways in which agents' position-practice systems enable and constrain ESD mainstreaming. It also demonstrates that a critical realist perspective can contribute towards the understanding and achievement of transformation towards sustainability and can help to ensure the flourishing of both current and future generations.
- Full Text:
Making (non) sense of urban water flows: Qualities and processes for transformative and transgressive learning moments
- Authors: James, Anna
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390665 , vital:68572 , xlink:href="https://doi.org/10.3390/su11236817"
- Description: Urban sustainability and justice depend upon the flow of water across complex urban space. Yet, the characteristics of urban space produce a fragmented sense of our water resources. Cape Town, South Africa, the context of this research, is one such city whose water challenges have been exacerbated by climate change-induced drought, to the extent that the city nearly shut off the water running to residents’ taps. This context presents a particular challenge for the focus of this special issue, transformative and transgressive learning, an emerging arena of thought and practice concerned with learning processes that might foster more sustainable socio-ecological relations. The empirical material for this research draws from 12 arts-based inquiry workshops run with youth in an environmental organisation over four months, exploring a local water crisis. The data were generated through an engaged arts-based research process. The paper traces how transformative and transgressive learning in the context of urban water crisis might be characterised as making (non)sense by bringing the empirical material into dialogue with five entry points of transformative and transgressive learning literature rooted in Freirean educational praxis. This paper crafts and engages the concept of making (non)sense, a way of thinking about qualities and processes of learning praxis that responds to the wicked sustainability challenges we face today, particularly in terms of a Global South perspective. I argue such a praxis needs qualities and processes that disrupt and trouble the norm in the context of the socio-ecological challenge of urban water.
- Full Text:
- Authors: James, Anna
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390665 , vital:68572 , xlink:href="https://doi.org/10.3390/su11236817"
- Description: Urban sustainability and justice depend upon the flow of water across complex urban space. Yet, the characteristics of urban space produce a fragmented sense of our water resources. Cape Town, South Africa, the context of this research, is one such city whose water challenges have been exacerbated by climate change-induced drought, to the extent that the city nearly shut off the water running to residents’ taps. This context presents a particular challenge for the focus of this special issue, transformative and transgressive learning, an emerging arena of thought and practice concerned with learning processes that might foster more sustainable socio-ecological relations. The empirical material for this research draws from 12 arts-based inquiry workshops run with youth in an environmental organisation over four months, exploring a local water crisis. The data were generated through an engaged arts-based research process. The paper traces how transformative and transgressive learning in the context of urban water crisis might be characterised as making (non)sense by bringing the empirical material into dialogue with five entry points of transformative and transgressive learning literature rooted in Freirean educational praxis. This paper crafts and engages the concept of making (non)sense, a way of thinking about qualities and processes of learning praxis that responds to the wicked sustainability challenges we face today, particularly in terms of a Global South perspective. I argue such a praxis needs qualities and processes that disrupt and trouble the norm in the context of the socio-ecological challenge of urban water.
- Full Text:
Mating preferences of two species of Eccritotarsus (Hemiptera: Miridae)
- Authors: Mnuguni, Sandiso
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417486 , vital:71457 , xlink:href="https://hdl.handle.net/10520/ejc-cristal-v10-n1-a7"
- Description: Eccritotarsus spp. are biological control agents that have been sourced from Brazil and Peru to control water hyacinth in South Africa. These agents have been released in over 30 sites and were thought to be the same species. The sequencing of mitochondrial DNA and interbreeding experiments have since confirmed the cryptic species to be separate species. The Brazilian population remains E. catarinensis while the Peruvian population is now E. eichhorniae. This paper assessed the mating behaviour of both species, to investigate behavioural traits that have resulted in reproductive isolation, which could have led to speciation. Mating choices in a form of no-choice, bi-choice and multi-choice tests were conducted within and between species in a 3:1, 2:1 and 1:1 sex ratio. The E. eichhorniae pair had more single and multiple copula incidences, higher average total copula duration and higher copula latency while the E.catarinensis♀×E.eichhorniae♂ pair had less single and multiple copula incidences, lower average total copula duration and lower copula latency. When the E.eichhorniae♀ and E.catarinensis♂ were given their respective choices, they only mated with conspecifics. However, when E.eichhorniae♀ are crossed with E.catarinensis♂ they do not produce offspring. These results suggest that interbreeding will be limited in South Africa.
- Full Text:
- Authors: Mnuguni, Sandiso
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417486 , vital:71457 , xlink:href="https://hdl.handle.net/10520/ejc-cristal-v10-n1-a7"
- Description: Eccritotarsus spp. are biological control agents that have been sourced from Brazil and Peru to control water hyacinth in South Africa. These agents have been released in over 30 sites and were thought to be the same species. The sequencing of mitochondrial DNA and interbreeding experiments have since confirmed the cryptic species to be separate species. The Brazilian population remains E. catarinensis while the Peruvian population is now E. eichhorniae. This paper assessed the mating behaviour of both species, to investigate behavioural traits that have resulted in reproductive isolation, which could have led to speciation. Mating choices in a form of no-choice, bi-choice and multi-choice tests were conducted within and between species in a 3:1, 2:1 and 1:1 sex ratio. The E. eichhorniae pair had more single and multiple copula incidences, higher average total copula duration and higher copula latency while the E.catarinensis♀×E.eichhorniae♂ pair had less single and multiple copula incidences, lower average total copula duration and lower copula latency. When the E.eichhorniae♀ and E.catarinensis♂ were given their respective choices, they only mated with conspecifics. However, when E.eichhorniae♀ are crossed with E.catarinensis♂ they do not produce offspring. These results suggest that interbreeding will be limited in South Africa.
- Full Text:
Methodological Survey of Simplified TD-DFT Methods for Fast and Accurate Interpretation of UV−Vis−NIR Spectra of Phthalocyanines
- Martynov, Alexander G, Mack, John, May, Aviwe K, Nyokong, Tebello, Gorbunova, Yulia G, Tsivadze, Aslan Yu
- Authors: Martynov, Alexander G , Mack, John , May, Aviwe K , Nyokong, Tebello , Gorbunova, Yulia G , Tsivadze, Aslan Yu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186915 , vital:44547 , xlink:href="https://doi.org/10.1021/acsomega.8b03500"
- Description: A methodological survey of density functional theory (DFT) methods for the prediction of UV−visible (vis)−near-infrared (NIR) spectra of phthalocyanines is reported. Four methods, namely, full time-dependent (TD)-DFT and its Tamm−Dancoff approximation (TDA), together with their simplified modifications (sTD-DFT and sTDA, respectively), were tested by using the examples of unsubstituted and alkoxy-substituted metal-free ligands and zinc complexes. The theoretical results were compared with experimental data derived from UV−visible absorption and magnetic circular dichroism spectroscopy. Seven popular exchange-correlation functionals (BP86, B3LYP, TPSSh, M06, CAM-B3LYP, LC-BLYP, and ωB97X) were tested within these four approaches starting at a relatively modest level using 6-31G(d) basis sets and gas-phase BP86/def2-SVP optimized geometries. A gradual augmentation of the computational levels was used to identify the influence of starting geometry, solvation effects, and basis sets on the results of TD-DFT and sTD-DFT calculations. It was found that although these factors do influence the predicted energies of the vertical excitations, they do not affect the trends predicted in the spectral properties across series of structurally related substituted free bases and metallophthalocyanines. The best accuracy for the gas-phase vertical excitations was observed in the lower-energy Q-band region for calculations that made use of range-separated hybrids for both full and simplified TD-DFT approaches. The CAMB3LYP functional provided particularly accurate results in the context of the sTD-DFT approach. The description of the higherenergy B-band region is considerably less accurate, and this demonstrates the need for further advances in the accuracy of theoretical calculations. Together with a general increase in accuracy, the application of simplified TD-DFT methods affords a 2−3 orders of magnitude speedup of the calculations in comparison to the full TD-DFT approach. It is anticipated that this approach will be widely used on desktop computers during the interpretation of UV−vis−NIR spectra of phthalocyanines and related macrocycles in the years ahead.
- Full Text:
- Authors: Martynov, Alexander G , Mack, John , May, Aviwe K , Nyokong, Tebello , Gorbunova, Yulia G , Tsivadze, Aslan Yu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186915 , vital:44547 , xlink:href="https://doi.org/10.1021/acsomega.8b03500"
- Description: A methodological survey of density functional theory (DFT) methods for the prediction of UV−visible (vis)−near-infrared (NIR) spectra of phthalocyanines is reported. Four methods, namely, full time-dependent (TD)-DFT and its Tamm−Dancoff approximation (TDA), together with their simplified modifications (sTD-DFT and sTDA, respectively), were tested by using the examples of unsubstituted and alkoxy-substituted metal-free ligands and zinc complexes. The theoretical results were compared with experimental data derived from UV−visible absorption and magnetic circular dichroism spectroscopy. Seven popular exchange-correlation functionals (BP86, B3LYP, TPSSh, M06, CAM-B3LYP, LC-BLYP, and ωB97X) were tested within these four approaches starting at a relatively modest level using 6-31G(d) basis sets and gas-phase BP86/def2-SVP optimized geometries. A gradual augmentation of the computational levels was used to identify the influence of starting geometry, solvation effects, and basis sets on the results of TD-DFT and sTD-DFT calculations. It was found that although these factors do influence the predicted energies of the vertical excitations, they do not affect the trends predicted in the spectral properties across series of structurally related substituted free bases and metallophthalocyanines. The best accuracy for the gas-phase vertical excitations was observed in the lower-energy Q-band region for calculations that made use of range-separated hybrids for both full and simplified TD-DFT approaches. The CAMB3LYP functional provided particularly accurate results in the context of the sTD-DFT approach. The description of the higherenergy B-band region is considerably less accurate, and this demonstrates the need for further advances in the accuracy of theoretical calculations. Together with a general increase in accuracy, the application of simplified TD-DFT methods affords a 2−3 orders of magnitude speedup of the calculations in comparison to the full TD-DFT approach. It is anticipated that this approach will be widely used on desktop computers during the interpretation of UV−vis−NIR spectra of phthalocyanines and related macrocycles in the years ahead.
- Full Text:
Methods for understanding social-ecological systems: a review of place-based studies
- de Vos, Alta, Biggs, Reinette, Preiser, Rika
- Authors: de Vos, Alta , Biggs, Reinette , Preiser, Rika
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415909 , vital:71299 , xlink:href="https://doi.org/10.5751/ES-11236-240416"
- Description: In recent years, social-ecological systems (SES) have emerged as a prominent analytical framing with which to investigate pressing sustainability issues associated with the Anthropocene era. Despite the growth of SES research, the lack of a delineated set of methods commonly contributes to disorientation for those entering into a field where methodological pluralism is the norm. We conduct a review of SES research, focusing particularly on methods used in this field. Our results reflect the rapid growth in SES research relative to other publications in relevant subject areas, and suggest a maturation of the field. Whilst institutions investigating SES have been mostly based in the global north, focal SES has been more globally distributed, although key regions, especially island regions, remain poorly studied. Key problems addressed in the studies related to policy, trade, conservation, adaptation, land use change, water, forests, sustainability, urban problems, and governance and institutions. We identified 311 methods, which we grouped into 27 method categories that can serve as a guide to SES research methods for newcomers to the field. We also performed an exploratory assessment of the ability of these methods to account for key features of SES as complex adaptive systems. We found that methods do better at accounting for the relational and context-dependent nature of SES, and least well with complex causality. Our study highlights the plurality of methods used in SES research, and helps highlight key areas in need of further methodological development.
- Full Text:
- Authors: de Vos, Alta , Biggs, Reinette , Preiser, Rika
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415909 , vital:71299 , xlink:href="https://doi.org/10.5751/ES-11236-240416"
- Description: In recent years, social-ecological systems (SES) have emerged as a prominent analytical framing with which to investigate pressing sustainability issues associated with the Anthropocene era. Despite the growth of SES research, the lack of a delineated set of methods commonly contributes to disorientation for those entering into a field where methodological pluralism is the norm. We conduct a review of SES research, focusing particularly on methods used in this field. Our results reflect the rapid growth in SES research relative to other publications in relevant subject areas, and suggest a maturation of the field. Whilst institutions investigating SES have been mostly based in the global north, focal SES has been more globally distributed, although key regions, especially island regions, remain poorly studied. Key problems addressed in the studies related to policy, trade, conservation, adaptation, land use change, water, forests, sustainability, urban problems, and governance and institutions. We identified 311 methods, which we grouped into 27 method categories that can serve as a guide to SES research methods for newcomers to the field. We also performed an exploratory assessment of the ability of these methods to account for key features of SES as complex adaptive systems. We found that methods do better at accounting for the relational and context-dependent nature of SES, and least well with complex causality. Our study highlights the plurality of methods used in SES research, and helps highlight key areas in need of further methodological development.
- Full Text:
Modeling top-down and bottom-up drivers of a regime shift in invasive aquatic plant stable states
- Strange, Emily F, Landi, Pietro, Hill, Jaclyn M, Coetzee, Julie A
- Authors: Strange, Emily F , Landi, Pietro , Hill, Jaclyn M , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444732 , vital:74263 , https://doi.org/10.3389/fpls.2019.00889
- Description: The evidence for alternate stable states characterized by dominance of either floating or submerged plant dominance is well established. Inspired by an existing model and controlled experiments, we conceptually describe a dynamic that we have observed in the field using a simple model, the aim of which was to investigate key interactions of the shift between invasive floating and invasive submerged plant dominance, driven by the rapid decomposition of floating plants as a consequence of herbivory by biological control agents. This study showed that the rate of switch between floating and submerged invasive plant dominance, and the point in time at which the switch occurs, is dependent on the nutrient status of the water and the density of biological control agents on floating plant populations. Therefore, top-down invasive plant biological control efforts using natural enemies can affect systems on a wider scale than the intended agent – plant level, and can be significantly altered by bottom-up changes to the system, i.e., nutrient loading. The implications of this are essential for understanding the multiple roles invasive plants and their control have upon ecosystem dynamics. The results emphasize the importance of multi-trophic considerations for future invasive plant management and offer evidence for new pathways of invasion. The model outputs support the conclusion that, after the shift and in the absence of effective intervention, a submerged invasive stable state will persist.
- Full Text:
- Authors: Strange, Emily F , Landi, Pietro , Hill, Jaclyn M , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444732 , vital:74263 , https://doi.org/10.3389/fpls.2019.00889
- Description: The evidence for alternate stable states characterized by dominance of either floating or submerged plant dominance is well established. Inspired by an existing model and controlled experiments, we conceptually describe a dynamic that we have observed in the field using a simple model, the aim of which was to investigate key interactions of the shift between invasive floating and invasive submerged plant dominance, driven by the rapid decomposition of floating plants as a consequence of herbivory by biological control agents. This study showed that the rate of switch between floating and submerged invasive plant dominance, and the point in time at which the switch occurs, is dependent on the nutrient status of the water and the density of biological control agents on floating plant populations. Therefore, top-down invasive plant biological control efforts using natural enemies can affect systems on a wider scale than the intended agent – plant level, and can be significantly altered by bottom-up changes to the system, i.e., nutrient loading. The implications of this are essential for understanding the multiple roles invasive plants and their control have upon ecosystem dynamics. The results emphasize the importance of multi-trophic considerations for future invasive plant management and offer evidence for new pathways of invasion. The model outputs support the conclusion that, after the shift and in the absence of effective intervention, a submerged invasive stable state will persist.
- Full Text:
Molecular identification and antibacterial properties of an ericoid associated mycorrhizal fungus
- Adeoyo, Olusegun R, Pletschke, Brett I, Dames, Joanna F
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440378 , vital:73778 , https://doi.org/10.1186/s12866-019-1555-y
- Description: The quest for novel sources of antibacterial compounds have necessitated the inclusion of ericoid mycorrhizal fungi (ERM) commonly found within the root of ericaceous plants. Agar-well diffusion method was used to detect antibacterial activity and was followed by the microbroth diffusion method [minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)].
- Full Text:
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440378 , vital:73778 , https://doi.org/10.1186/s12866-019-1555-y
- Description: The quest for novel sources of antibacterial compounds have necessitated the inclusion of ericoid mycorrhizal fungi (ERM) commonly found within the root of ericaceous plants. Agar-well diffusion method was used to detect antibacterial activity and was followed by the microbroth diffusion method [minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)].
- Full Text:
Morphological identification of fungi associated with Eichhornia crassipes (Mart.-Solms) Laubach in the Wouri River Basin, Douala, Cameroon
- Voukeng, Kenfack S N, Coombes, Candice A, Weyl, Philip S R, Djeugoue, F, Hill, Martin P
- Authors: Voukeng, Kenfack S N , Coombes, Candice A , Weyl, Philip S R , Djeugoue, F , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423785 , vital:72093 , xlink:href="https://doi.org/10.2989/16085914.2019.1636760"
- Description: In many parts of the world, excess growth of Eichhornia crassipes (Pontederiaceae) poses a serious threat to aquatic environments. In Cameroon, where manual clearing is still undertaken, little is known about fungal diversity associated with the plant, or its potential for biological control. Surveys of the Wouri River Basin in the Littoral Region of Cameroon were conducted during a rainy season (May–October 2014) and a dry season (November 2015–April 2016) at various sites, to identify fungi associated with water hyacinth. Fungi were isolated and identified from symptomatic plant parts collected. In the rainy season, 130 fungal isolates belonging to 12 genera were identified morphologically, whereas 299 isolates belonging to 23 genera were identified during the dry season. With the exception of Fusarium oxysporum and Phytophthora sp., the genera represented new records for Cameroon, and Chaetomium strumarium, Colletotrichum gloesporioides, C. acutatum, C. dematium, Curvularia pallescens and Pytomyces chartarum were considered new host records for E. crassipes in Africa. Isolates of Acremonium zonatum, Chaetomium strumarium, Alternaria eichhorniae, Phytophthora sp. and Rhizoctonia sp. showed the highest frequency of occurrence on E. crassipes in the Wouri River Basin and, given their record as plant pathogens, could be potentially useful in the development of mycoherbicides for this weed in Cameroon.
- Full Text:
- Authors: Voukeng, Kenfack S N , Coombes, Candice A , Weyl, Philip S R , Djeugoue, F , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423785 , vital:72093 , xlink:href="https://doi.org/10.2989/16085914.2019.1636760"
- Description: In many parts of the world, excess growth of Eichhornia crassipes (Pontederiaceae) poses a serious threat to aquatic environments. In Cameroon, where manual clearing is still undertaken, little is known about fungal diversity associated with the plant, or its potential for biological control. Surveys of the Wouri River Basin in the Littoral Region of Cameroon were conducted during a rainy season (May–October 2014) and a dry season (November 2015–April 2016) at various sites, to identify fungi associated with water hyacinth. Fungi were isolated and identified from symptomatic plant parts collected. In the rainy season, 130 fungal isolates belonging to 12 genera were identified morphologically, whereas 299 isolates belonging to 23 genera were identified during the dry season. With the exception of Fusarium oxysporum and Phytophthora sp., the genera represented new records for Cameroon, and Chaetomium strumarium, Colletotrichum gloesporioides, C. acutatum, C. dematium, Curvularia pallescens and Pytomyces chartarum were considered new host records for E. crassipes in Africa. Isolates of Acremonium zonatum, Chaetomium strumarium, Alternaria eichhorniae, Phytophthora sp. and Rhizoctonia sp. showed the highest frequency of occurrence on E. crassipes in the Wouri River Basin and, given their record as plant pathogens, could be potentially useful in the development of mycoherbicides for this weed in Cameroon.
- Full Text:
Morphological influence of deposition routes on lead sulfide thin films
- Mlowe, Sixberth, Shombe, Ginena B, Akerman, Matthew P, Mubofu, Egid B, O'Brien, Paul, Mashazi, Philani N, Nyokong, Tebello, Revaprasadu, Neerish
- Authors: Mlowe, Sixberth , Shombe, Ginena B , Akerman, Matthew P , Mubofu, Egid B , O'Brien, Paul , Mashazi, Philani N , Nyokong, Tebello , Revaprasadu, Neerish
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186780 , vital:44533 , xlink:href="https://doi.org/10.1016/j.ica.2019.119116"
- Description: A distorted single crystal structure of bis(piperidinedithiocarbamato)lead(II) complex and its subsequent use to deposit thin films is reported. Two deposition routes namely, aerosol-assisted chemical vapour deposition (AACVD) and spin coating deposition have been employed to obtain anisotropic lead sulfide (PbS) nanostructures. The thin films displayed rod to cubic shaped crystals for AACVD, and a range of cubes, star and dendritic morphologies with variation of temperatures were displayed for spin coated films. Optical band gaps between 1.32 and 1.55 eV as controlled by the change in temperature were observed for thin films deposited by AACVD. Powder X-ray diffraction (P-XRD) studies show that the films formed are composed of cubic crystalline PbS. The X-ray photoelectron spectroscopy (XPS) was used to investigate the effect of activation temperatures (350, 400 and 450 °C) on the chemical composition and oxidation states of PbS samples.
- Full Text:
- Authors: Mlowe, Sixberth , Shombe, Ginena B , Akerman, Matthew P , Mubofu, Egid B , O'Brien, Paul , Mashazi, Philani N , Nyokong, Tebello , Revaprasadu, Neerish
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186780 , vital:44533 , xlink:href="https://doi.org/10.1016/j.ica.2019.119116"
- Description: A distorted single crystal structure of bis(piperidinedithiocarbamato)lead(II) complex and its subsequent use to deposit thin films is reported. Two deposition routes namely, aerosol-assisted chemical vapour deposition (AACVD) and spin coating deposition have been employed to obtain anisotropic lead sulfide (PbS) nanostructures. The thin films displayed rod to cubic shaped crystals for AACVD, and a range of cubes, star and dendritic morphologies with variation of temperatures were displayed for spin coated films. Optical band gaps between 1.32 and 1.55 eV as controlled by the change in temperature were observed for thin films deposited by AACVD. Powder X-ray diffraction (P-XRD) studies show that the films formed are composed of cubic crystalline PbS. The X-ray photoelectron spectroscopy (XPS) was used to investigate the effect of activation temperatures (350, 400 and 450 °C) on the chemical composition and oxidation states of PbS samples.
- Full Text:
Multi-directional effects of warming temperatures on the reproductive success of a threatened alpine-endemic bird, and implications for conservation management
- Oswald, Krista N, Lee, Alan T K, Diener, John P, Diener, Elizabeth F, Cunningham, Susan J, Smit, Ben
- Authors: Oswald, Krista N , Lee, Alan T K , Diener, John P , Diener, Elizabeth F , Cunningham, Susan J , Smit, Ben
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441624 , vital:73902 , https://eco.confex.com/eco/2019/meetingapp.cgi/Paper/78223
- Description: Mitigating the current biodiversity crisis requires a better understanding of how species will respond to future climate change and human impacts on habi-tat. Decreased reproductive capability, due to changes in phenology, output, and success, is one of the main indicators of species’ vulnerability. For terres-trial ground-nesting birds, overall reproductive success is often related to nest-site selection (e.g. increased nest concealment), and weather changes (e.g. higher air temperatures alter nest success). We investigated the reproductive success of Cape Rockjumpers (Chaetops frenatus; “Rockjumpers”), a ground-nesting alpine bird, endemic to the Fynbos biome of South Africa, whose popu-lation decline correlates to warmer temperatures. We predicted that breeding success would be positively correlated with increased nest concealment, and negatively correlated with increasing temperature. We collected data over three years, including two full breeding seasons, from 2016 to 2018 (n=5, n=20 and n=43 respectively), which included nest-site selection variables (i.e. vege-tative cover, rock cover, time since fire in years), success or failure (whether nest resulted in ≥ fledgling), and cause if nest failed (i.e. predation events, weather). We tested the overall success in relation to nest-site selection varia-bles, and then examined how nest failure (specifically snake predation) was correlated with air temperature.
- Full Text:
- Authors: Oswald, Krista N , Lee, Alan T K , Diener, John P , Diener, Elizabeth F , Cunningham, Susan J , Smit, Ben
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441624 , vital:73902 , https://eco.confex.com/eco/2019/meetingapp.cgi/Paper/78223
- Description: Mitigating the current biodiversity crisis requires a better understanding of how species will respond to future climate change and human impacts on habi-tat. Decreased reproductive capability, due to changes in phenology, output, and success, is one of the main indicators of species’ vulnerability. For terres-trial ground-nesting birds, overall reproductive success is often related to nest-site selection (e.g. increased nest concealment), and weather changes (e.g. higher air temperatures alter nest success). We investigated the reproductive success of Cape Rockjumpers (Chaetops frenatus; “Rockjumpers”), a ground-nesting alpine bird, endemic to the Fynbos biome of South Africa, whose popu-lation decline correlates to warmer temperatures. We predicted that breeding success would be positively correlated with increased nest concealment, and negatively correlated with increasing temperature. We collected data over three years, including two full breeding seasons, from 2016 to 2018 (n=5, n=20 and n=43 respectively), which included nest-site selection variables (i.e. vege-tative cover, rock cover, time since fire in years), success or failure (whether nest resulted in ≥ fledgling), and cause if nest failed (i.e. predation events, weather). We tested the overall success in relation to nest-site selection varia-bles, and then examined how nest failure (specifically snake predation) was correlated with air temperature.
- Full Text:
Nano-enabled liposomal mucoadhesive films for enhanced efavirenz buccal drug delivery
- Okafor, Nnamadi I, Ngoepe, Mpho, Siwe-Noundou, Xavier, Krause, Rui W M
- Authors: Okafor, Nnamadi I , Ngoepe, Mpho , Siwe-Noundou, Xavier , Krause, Rui W M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/194032 , vital:45417 , xlink:href="https://doi.org/10.1016/j.jddst.2019.101312"
- Description: Buccal films (BFs) were prepared using a solvent casting method using the liposomal suspension as the dispersing medium. Optimization of some physical properties of the films containing different amounts of polymers was done using digital Vernier calliper and digital weighing balance. The physiochemical properties of the best optimized properties were characterized using Differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Energy dispersive X-ray spectroscopy (EDS), and Scanning Electron Microscopy (SEM). Permeation study of the BFs composed of Carbopol (CP) alone and CP to Pluronic 127 (PF127) demonstrated better bio-adhesive properties than the films made of other polymers such as HPMC (hydroxyl propyl methyl cellulose) and HPMC-PF127. These CP based BFs (without and with PF127) exhibited good film thickness 0.88 ± 0.10 and 0.76 ± 0.14 mm, with weight uniformity 68.22 ± 1.04 and 86.28 ± 2.16 mg, satisfactory flexibility values 258 and 321, and slightly acidic pH 6.43 ± 0.76 and 6.32 ± 0.01. The swelling percentage was found to be 50% for CP and 78% for CP-PF127. The cumulative amount of drug that permeated through the buccal epithelium after 24 h was about 66% from CP and 75% from CP-PF127.
- Full Text:
- Authors: Okafor, Nnamadi I , Ngoepe, Mpho , Siwe-Noundou, Xavier , Krause, Rui W M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/194032 , vital:45417 , xlink:href="https://doi.org/10.1016/j.jddst.2019.101312"
- Description: Buccal films (BFs) were prepared using a solvent casting method using the liposomal suspension as the dispersing medium. Optimization of some physical properties of the films containing different amounts of polymers was done using digital Vernier calliper and digital weighing balance. The physiochemical properties of the best optimized properties were characterized using Differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Energy dispersive X-ray spectroscopy (EDS), and Scanning Electron Microscopy (SEM). Permeation study of the BFs composed of Carbopol (CP) alone and CP to Pluronic 127 (PF127) demonstrated better bio-adhesive properties than the films made of other polymers such as HPMC (hydroxyl propyl methyl cellulose) and HPMC-PF127. These CP based BFs (without and with PF127) exhibited good film thickness 0.88 ± 0.10 and 0.76 ± 0.14 mm, with weight uniformity 68.22 ± 1.04 and 86.28 ± 2.16 mg, satisfactory flexibility values 258 and 321, and slightly acidic pH 6.43 ± 0.76 and 6.32 ± 0.01. The swelling percentage was found to be 50% for CP and 78% for CP-PF127. The cumulative amount of drug that permeated through the buccal epithelium after 24 h was about 66% from CP and 75% from CP-PF127.
- Full Text:
Navigating non-sense by exemplifying situated life experience and intergenerational heritage knowledge in Education for Sustainable Development learning spaces
- O'Donoghue, Rob B, Kibuka-Sebitosi, Esther, Tshiningayamwe, Sirkka A N, Palmer, Carl
- Authors: O'Donoghue, Rob B , Kibuka-Sebitosi, Esther , Tshiningayamwe, Sirkka A N , Palmer, Carl
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/388122 , vital:68308 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/186410"
- Description: This paper uses an activity system perspective to probe the related problems of knowledge abstraction and a lack of relevance as a modern legacy of colonial education practices in Africa. Its purpose is to contemplate Education for Sustainable Development (ESD) pedagogy to support learning that might be better situated in and resonate with local African contexts and the emerging sustainability concerns in everyday life. Colonial education trajectories and the recent inclusion of new environmental knowledge in African curriculum and civic learning contexts are examined. This points to how circulating environment and sustainability knowledge is being constituted in disciplinary fields as abstract concepts that are often difficult to relate to local sustainability concerns. Socio-cultural heritage and intergenerational meaning making are explored to uncover better situated ways of navigating much of the abstract ‘non-sense’ confronting African learners in many modern education contexts today. Illustrative examples of historical patterns of exclusion are scoped and two cases of pedagogical innovation are examined to contemplate how to navigate better situated and more relevant learning processes. Enacted in situated and co-engaged ways, ESD practices may enable the socio-cultural capital and environmental realities of local social-ecological contexts to articulate with better situated sustainability propositions for transitioning to more peaceful, just and sustainable futures.
- Full Text:
- Authors: O'Donoghue, Rob B , Kibuka-Sebitosi, Esther , Tshiningayamwe, Sirkka A N , Palmer, Carl
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/388122 , vital:68308 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/186410"
- Description: This paper uses an activity system perspective to probe the related problems of knowledge abstraction and a lack of relevance as a modern legacy of colonial education practices in Africa. Its purpose is to contemplate Education for Sustainable Development (ESD) pedagogy to support learning that might be better situated in and resonate with local African contexts and the emerging sustainability concerns in everyday life. Colonial education trajectories and the recent inclusion of new environmental knowledge in African curriculum and civic learning contexts are examined. This points to how circulating environment and sustainability knowledge is being constituted in disciplinary fields as abstract concepts that are often difficult to relate to local sustainability concerns. Socio-cultural heritage and intergenerational meaning making are explored to uncover better situated ways of navigating much of the abstract ‘non-sense’ confronting African learners in many modern education contexts today. Illustrative examples of historical patterns of exclusion are scoped and two cases of pedagogical innovation are examined to contemplate how to navigate better situated and more relevant learning processes. Enacted in situated and co-engaged ways, ESD practices may enable the socio-cultural capital and environmental realities of local social-ecological contexts to articulate with better situated sustainability propositions for transitioning to more peaceful, just and sustainable futures.
- Full Text:
Nest site choice by the intertidal spider Desis formidabilis (Araneae: Desidae) and nest utilisation by its hymenopteran egg parasitoid
- Owen, Candice A, van Noort, Simon, Compton, Stephen G, Coetzee, Julie A
- Authors: Owen, Candice A , van Noort, Simon , Compton, Stephen G , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444436 , vital:74240 , https://doi.org/10.1111/een.12675
- Description: Echthrodesis lamorali Masner, 1968 is the only known parasitoid of the eggs of the intertidal rocky shore spider Desis formidabilis O.P. Cam-bridge 1890 and is endemic to a small area of South Africa. The abun-dance of spider nests and parasitoid presence were assessed in rela-tion to their in‐ and between‐shore location at multiple sites within the distribution of E. lamorali along the Cape Peninsula (Western Cape, South Africa).
- Full Text:
- Authors: Owen, Candice A , van Noort, Simon , Compton, Stephen G , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444436 , vital:74240 , https://doi.org/10.1111/een.12675
- Description: Echthrodesis lamorali Masner, 1968 is the only known parasitoid of the eggs of the intertidal rocky shore spider Desis formidabilis O.P. Cam-bridge 1890 and is endemic to a small area of South Africa. The abun-dance of spider nests and parasitoid presence were assessed in rela-tion to their in‐ and between‐shore location at multiple sites within the distribution of E. lamorali along the Cape Peninsula (Western Cape, South Africa).
- Full Text:
New type of metal-free and Zinc (II), In (III), Ga (III) phthalocyanines carrying biologically active substituents: Synthesis and photophysicochemical properties and photodynamic therapy activity
- Sen, Pinar, Managa, Muthumuni, Nyokong, Tebello
- Authors: Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186971 , vital:44552 , xlink:href="https://doi.org/10.1016/j.ica.2019.03.010"
- Description: This study reports on novel phthalocyanines having benzimidazole units which are known to have biological properties. 4-(4-(5-chloro-1H-benzo[d]imidazol-2-yl) substituted metal-free, Zn(II), In(III) and Ga(III) phthalocyanines were synthesized, these newly synthesized molecules that were substituted by oxygen bridges were fully characterized. For the purpose of determining their potency for photodynamic therapy, the photophysicochemical properties were investigated in DMSO. The H2Pc (4) showed higher fluorescence quantum yield and fluorescence lifetime as compared to metallated phthalocyanines derivatives. However, the highest singlet oxygen (ΦΔ) and triplet state quantum yields (ΦT) values were obtained with the In(III)Pc (5).
- Full Text:
- Authors: Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186971 , vital:44552 , xlink:href="https://doi.org/10.1016/j.ica.2019.03.010"
- Description: This study reports on novel phthalocyanines having benzimidazole units which are known to have biological properties. 4-(4-(5-chloro-1H-benzo[d]imidazol-2-yl) substituted metal-free, Zn(II), In(III) and Ga(III) phthalocyanines were synthesized, these newly synthesized molecules that were substituted by oxygen bridges were fully characterized. For the purpose of determining their potency for photodynamic therapy, the photophysicochemical properties were investigated in DMSO. The H2Pc (4) showed higher fluorescence quantum yield and fluorescence lifetime as compared to metallated phthalocyanines derivatives. However, the highest singlet oxygen (ΦΔ) and triplet state quantum yields (ΦT) values were obtained with the In(III)Pc (5).
- Full Text:
Nonlinear optical behavior of n-tuple decker phthalocyanines at the nanosecond regime
- Sekhosana, Kutloana E, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234603 , vital:50212 , xlink:href="https://doi.org/10.1039/C9RA01836K"
- Description: The coordination system of rare-earth n-tuple decker phthalocyanines would be better suited with appropriate metal ions with the correct coordination number and the solvent system of the reaction, amongst other reasons, for the formation of n-tuple decker phthalocyanines. As a result, these complexes are very rare. In this manuscript, we present new n-tuple decker phthalocyanines in the form of double- (complex 2), quadruple- (complex 3a) and sextuple-decker phthalocyanines (complex 3b), all of which contain neodymium and cadmium metal ions. The primary focus is the investigation of the nonlinear optical (NLO) mechanisms responsible for the observed reverse saturable absorption. While the extension of the π-electron system has been found to enhance the nonlinear optical behavior of complexes 3a and 3b, a change in the NLO mechanisms has been observed, with complex 2 lacking the triplet state population, as revealed by a laser flash photolysis technique. It has also been established that the excited state absorption cross sections follow a clear order of magnitude for the complexes under investigation: σ23 (for 3b) > σ23 (for 3a) > σ1m (for 2). This trend evidences the effects of the extension of the π-electron system.
- Full Text:
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234603 , vital:50212 , xlink:href="https://doi.org/10.1039/C9RA01836K"
- Description: The coordination system of rare-earth n-tuple decker phthalocyanines would be better suited with appropriate metal ions with the correct coordination number and the solvent system of the reaction, amongst other reasons, for the formation of n-tuple decker phthalocyanines. As a result, these complexes are very rare. In this manuscript, we present new n-tuple decker phthalocyanines in the form of double- (complex 2), quadruple- (complex 3a) and sextuple-decker phthalocyanines (complex 3b), all of which contain neodymium and cadmium metal ions. The primary focus is the investigation of the nonlinear optical (NLO) mechanisms responsible for the observed reverse saturable absorption. While the extension of the π-electron system has been found to enhance the nonlinear optical behavior of complexes 3a and 3b, a change in the NLO mechanisms has been observed, with complex 2 lacking the triplet state population, as revealed by a laser flash photolysis technique. It has also been established that the excited state absorption cross sections follow a clear order of magnitude for the complexes under investigation: σ23 (for 3b) > σ23 (for 3a) > σ1m (for 2). This trend evidences the effects of the extension of the π-electron system.
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