Monitoring and evaluation in a changing world: A Southern African perspective on the skills needed for a new approach
- Rosenberg, Eureta, Kotschy, Karen
- Authors: Rosenberg, Eureta , Kotschy, Karen
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370711 , vital:66369 , xlink:href="https://doi.org/ 10.4102/aej.v8i1.472"
- Description: Background: As science and modern technology have brought many advances, we have also come to overshoot planetary boundaries, while still falling short of development goals to eradicate poverty and inequality. A growing recognition of the complexity of development problems and contexts calls for new framings, including a new approach to monitoring and evaluation (M and E) as one of the mechanisms by which modern societies aim to steer towards a more sustainable future. New approaches to M and E mean new skills for the M and E practitioner. Objectives: This article proposed a framing for M and E skills, comprising of technical, relational and transformational (T-R-T) competences. Method: Adapted from the literature, this competence framework was tested in a broader learning needs assessment and then applied retrospectively to author’s experience in developmental evaluations in complex social–ecological contexts in southern Africa. Results: The emerging insights were that not only technical competence is needed, but also relational competence that goes beyond interpersonal skills, to enable the production and uptake of evaluation findings. In addition, the limitations of mainstream M and E methods in the face of complexity seemed to create a need for ‘transformational’ competence, which included evaluators’ ability to develop credible M and E alternatives. Conclusion: The T-R-T framework helped to advance the notions of ‘hard’ and ‘soft’ skills and expanded on existing M and E competence frameworks. Recommendations included a call for innovative educational and professional development approaches to develop relational and transformational competencies, in addition to training for technical competence.
- Full Text:
- Date Issued: 2020
- Authors: Rosenberg, Eureta , Kotschy, Karen
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370711 , vital:66369 , xlink:href="https://doi.org/ 10.4102/aej.v8i1.472"
- Description: Background: As science and modern technology have brought many advances, we have also come to overshoot planetary boundaries, while still falling short of development goals to eradicate poverty and inequality. A growing recognition of the complexity of development problems and contexts calls for new framings, including a new approach to monitoring and evaluation (M and E) as one of the mechanisms by which modern societies aim to steer towards a more sustainable future. New approaches to M and E mean new skills for the M and E practitioner. Objectives: This article proposed a framing for M and E skills, comprising of technical, relational and transformational (T-R-T) competences. Method: Adapted from the literature, this competence framework was tested in a broader learning needs assessment and then applied retrospectively to author’s experience in developmental evaluations in complex social–ecological contexts in southern Africa. Results: The emerging insights were that not only technical competence is needed, but also relational competence that goes beyond interpersonal skills, to enable the production and uptake of evaluation findings. In addition, the limitations of mainstream M and E methods in the face of complexity seemed to create a need for ‘transformational’ competence, which included evaluators’ ability to develop credible M and E alternatives. Conclusion: The T-R-T framework helped to advance the notions of ‘hard’ and ‘soft’ skills and expanded on existing M and E competence frameworks. Recommendations included a call for innovative educational and professional development approaches to develop relational and transformational competencies, in addition to training for technical competence.
- Full Text:
- Date Issued: 2020
Multi-layered risk management in under-resourced antenatal clinics
- Feltham-King, Tracey, Macleod, Catriona I
- Authors: Feltham-King, Tracey , Macleod, Catriona I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298561 , vital:57716 , xlink:href="https://doi.org/10.1080/13698575.2019.1697432"
- Description: In this article we contribute to critical risk approaches to studying pregnancy and childbirth in the global South. Following Sarah Rudrum’s work, our approach focusses on sociocultural inequalities amid the regulation of individuals. We draw on data from our Foucauldian-inspired ethnography of two antenatal clinics in an under-resourced area of South Africa to illustrate how multi-layered risk management operates in these spaces. These data were collected over a period of six months in the form of semi-structured interviews, observations of consultations and waiting room interactions, documents used in the clinic, and posters appearing on the clinic walls. Our findings show how a scientific-bureaucratic approach to pregnancy risk management, as encoded in international, national and institutional guidelines, is well known, highly visible, and practised through surveillance and reporting mechanisms in clinics. This approach incites healthcare practitioners to achieve particular performance standards and to monitor their professional agency. Managing pregnancy risk thus entails regulating the healthcare practitioners themselves. In implementing approved pregnancy risk management strategies in an over-subscribed and under-resourced public healthcare setting, however, healthcare practitioners face potential risk to their professional reputation and integrity. In managing this risk, they resist the scientific-bureaucratic approach through: depicting themselves as victims of unfair institutional arrangements or unreasonable patients; instituting street-level bureaucracy to control access to the clinics; and controlling patients’ actions in authoritarian ways. Our research shows that without engagement with the on-the-ground realities of the antenatal clinic in resource-poor environments, a scientific-bureaucratic approach to pregnancy risk management is inevitably limited in its effectiveness.
- Full Text:
- Date Issued: 2020
- Authors: Feltham-King, Tracey , Macleod, Catriona I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298561 , vital:57716 , xlink:href="https://doi.org/10.1080/13698575.2019.1697432"
- Description: In this article we contribute to critical risk approaches to studying pregnancy and childbirth in the global South. Following Sarah Rudrum’s work, our approach focusses on sociocultural inequalities amid the regulation of individuals. We draw on data from our Foucauldian-inspired ethnography of two antenatal clinics in an under-resourced area of South Africa to illustrate how multi-layered risk management operates in these spaces. These data were collected over a period of six months in the form of semi-structured interviews, observations of consultations and waiting room interactions, documents used in the clinic, and posters appearing on the clinic walls. Our findings show how a scientific-bureaucratic approach to pregnancy risk management, as encoded in international, national and institutional guidelines, is well known, highly visible, and practised through surveillance and reporting mechanisms in clinics. This approach incites healthcare practitioners to achieve particular performance standards and to monitor their professional agency. Managing pregnancy risk thus entails regulating the healthcare practitioners themselves. In implementing approved pregnancy risk management strategies in an over-subscribed and under-resourced public healthcare setting, however, healthcare practitioners face potential risk to their professional reputation and integrity. In managing this risk, they resist the scientific-bureaucratic approach through: depicting themselves as victims of unfair institutional arrangements or unreasonable patients; instituting street-level bureaucracy to control access to the clinics; and controlling patients’ actions in authoritarian ways. Our research shows that without engagement with the on-the-ground realities of the antenatal clinic in resource-poor environments, a scientific-bureaucratic approach to pregnancy risk management is inevitably limited in its effectiveness.
- Full Text:
- Date Issued: 2020
Mycorrhizal Interventions for Sustainable Potato Production in Africa
- Chifetete, Varaidzo W, Dames, Joanna F
- Authors: Chifetete, Varaidzo W , Dames, Joanna F
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426021 , vital:72307 , xlink:href="https://doi.org/10.3389/fsufs.2020.593053"
- Description: The potato (Solanum tuberosum L.) is an important tuber crop with high dietary value that could potentially help to alleviate malnutrition and hunger in Africa. However, production is expensive, with high fertilizer and pesticide demands that lead to environmental pollution, and tillage practices that negatively affect soil structure. Microorganisms of different types have increasingly been found to be useful as biofertilizers, and arbuscular mycorrhizal (AM) fungi are an important crop symbiont. AM fungi have been shown to increase tolerance of crop plants to drought, salinity and disease by facilitating water and nutrient acquisition and by improving overall soil structure. However, the establishment and maintenance of the symbioses are greatly affected by agricultural practices. Here, we review the benefits that AM fungi confer in potato production, discuss the role and importance of mycorrhiza helper bacteria, and focus on how AM fungal diversity and abundance can be affected by conventional agricultural practices, such as those used in potato production. We suggest approaches for maintaining AM fungal abundance in potato production by highlighting the potential of conservation tillage practices augmented with cover crops and crop rotations. An approach that balances weed control, nutrient provision, and AM fungal helper bacterial populations, whilst promoting functional AM fungal populations for varying potato genotypes, will stimulate efficient mycorrhizal interventions.
- Full Text:
- Date Issued: 2020
- Authors: Chifetete, Varaidzo W , Dames, Joanna F
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426021 , vital:72307 , xlink:href="https://doi.org/10.3389/fsufs.2020.593053"
- Description: The potato (Solanum tuberosum L.) is an important tuber crop with high dietary value that could potentially help to alleviate malnutrition and hunger in Africa. However, production is expensive, with high fertilizer and pesticide demands that lead to environmental pollution, and tillage practices that negatively affect soil structure. Microorganisms of different types have increasingly been found to be useful as biofertilizers, and arbuscular mycorrhizal (AM) fungi are an important crop symbiont. AM fungi have been shown to increase tolerance of crop plants to drought, salinity and disease by facilitating water and nutrient acquisition and by improving overall soil structure. However, the establishment and maintenance of the symbioses are greatly affected by agricultural practices. Here, we review the benefits that AM fungi confer in potato production, discuss the role and importance of mycorrhiza helper bacteria, and focus on how AM fungal diversity and abundance can be affected by conventional agricultural practices, such as those used in potato production. We suggest approaches for maintaining AM fungal abundance in potato production by highlighting the potential of conservation tillage practices augmented with cover crops and crop rotations. An approach that balances weed control, nutrient provision, and AM fungal helper bacterial populations, whilst promoting functional AM fungal populations for varying potato genotypes, will stimulate efficient mycorrhizal interventions.
- Full Text:
- Date Issued: 2020
Nano-biomimetic drug delivery vehicles: Potential approaches for COVID-19 treatment
- Witika, Bwalya A, Makoni, Pedzisai A, Mweetwa, Larry L, Ntemi, Pascal V, Chikukwa, Mellisa T R, Matafwali, Scott K, Mwila, Chiluba, Mudenda, Steward, Katandula, Jonathan, Walker, Roderick B
- Authors: Witika, Bwalya A , Makoni, Pedzisai A , Mweetwa, Larry L , Ntemi, Pascal V , Chikukwa, Mellisa T R , Matafwali, Scott K , Mwila, Chiluba , Mudenda, Steward , Katandula, Jonathan , Walker, Roderick B
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183440 , vital:43991 , xlink:href="https://doi.org/10.3390/molecules25245952"
- Description: The current COVID-19 pandemic has tested the resolve of the global community with more than 35 million infections worldwide and numbers increasing with no cure or vaccine available to date. Nanomedicines have an advantage of providing enhanced permeability and retention and have been extensively studied as targeted drug delivery strategies for the treatment of different disease. The role of monocytes, erythrocytes, thrombocytes, and macrophages in diseases, including infectious and inflammatory diseases, cancer, and atherosclerosis, are better understood and have resulted in improved strategies for targeting and in some instances mimicking these cell types to improve therapeutic outcomes. Consequently, these primary cell types can be exploited for the purposes of serving as a "Trojan horse" for targeted delivery to identified organs and sites of inflammation. State of the art and potential utilization of nanocarriers such as nanospheres/nanocapsules, nanocrystals, liposomes, solid lipid nanoparticles/nano-structured lipid carriers, dendrimers, and nanosponges for biomimicry and/or targeted delivery of bioactives to cells are reported herein and their potential use in the treatment of COVID-19 infections discussed. Physicochemical properties, viz., hydrophilicity, particle shape, surface charge, composition, concentration, the use of different target-specific ligands on the surface of carriers, and the impact on carrier efficacy and specificity are also discussed.
- Full Text:
- Date Issued: 2020
- Authors: Witika, Bwalya A , Makoni, Pedzisai A , Mweetwa, Larry L , Ntemi, Pascal V , Chikukwa, Mellisa T R , Matafwali, Scott K , Mwila, Chiluba , Mudenda, Steward , Katandula, Jonathan , Walker, Roderick B
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183440 , vital:43991 , xlink:href="https://doi.org/10.3390/molecules25245952"
- Description: The current COVID-19 pandemic has tested the resolve of the global community with more than 35 million infections worldwide and numbers increasing with no cure or vaccine available to date. Nanomedicines have an advantage of providing enhanced permeability and retention and have been extensively studied as targeted drug delivery strategies for the treatment of different disease. The role of monocytes, erythrocytes, thrombocytes, and macrophages in diseases, including infectious and inflammatory diseases, cancer, and atherosclerosis, are better understood and have resulted in improved strategies for targeting and in some instances mimicking these cell types to improve therapeutic outcomes. Consequently, these primary cell types can be exploited for the purposes of serving as a "Trojan horse" for targeted delivery to identified organs and sites of inflammation. State of the art and potential utilization of nanocarriers such as nanospheres/nanocapsules, nanocrystals, liposomes, solid lipid nanoparticles/nano-structured lipid carriers, dendrimers, and nanosponges for biomimicry and/or targeted delivery of bioactives to cells are reported herein and their potential use in the treatment of COVID-19 infections discussed. Physicochemical properties, viz., hydrophilicity, particle shape, surface charge, composition, concentration, the use of different target-specific ligands on the surface of carriers, and the impact on carrier efficacy and specificity are also discussed.
- Full Text:
- Date Issued: 2020
New difluoroboron complexes based on N, O-chelated Schiff base ligands: Synthesis, characterization, DFT calculations and photophysical and electrochemical properties
- Sen, Pinar, Mpeta, Lekhetho S, Mack, John, Nyokong, Tebello
- Authors: Sen, Pinar , Mpeta, Lekhetho S , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186207 , vital:44473 , xlink:href="https://doi.org/10.1016/j.jlumin.2020.117262"
- Description: The synthesis of new Schiff bases and their dinuclear boron complexes is described, along with their characterization by 1H and 13C NMR, FT-IR, and UV–visible absorption spectroscopy, mass spectrometry, and EDX for elemental analysis. The optical and photophysical properties were examined in terms of their absorption and emission behavior, fluorescence quantum yields and fluorescence lifetimes. The flexible dinuclear boron complexes that are linked by a flexible carbon chain exhibited large Stokes shifts in the range from 92 nm to 115 nm in contrast to BODIPY dyes. Those properties make these complexes precious for applications in fluorescence materials. And also theoretical calculations were obtained by using Density Functional Theory (DFT) methods.
- Full Text:
- Date Issued: 2020
- Authors: Sen, Pinar , Mpeta, Lekhetho S , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186207 , vital:44473 , xlink:href="https://doi.org/10.1016/j.jlumin.2020.117262"
- Description: The synthesis of new Schiff bases and their dinuclear boron complexes is described, along with their characterization by 1H and 13C NMR, FT-IR, and UV–visible absorption spectroscopy, mass spectrometry, and EDX for elemental analysis. The optical and photophysical properties were examined in terms of their absorption and emission behavior, fluorescence quantum yields and fluorescence lifetimes. The flexible dinuclear boron complexes that are linked by a flexible carbon chain exhibited large Stokes shifts in the range from 92 nm to 115 nm in contrast to BODIPY dyes. Those properties make these complexes precious for applications in fluorescence materials. And also theoretical calculations were obtained by using Density Functional Theory (DFT) methods.
- Full Text:
- Date Issued: 2020
NIR Absorbing AzaBODIPY Dyes for pH Sensing
- Kubheka, Gugu, Mack, John, Nyokong, Tebello, Zhen, Shen
- Authors: Kubheka, Gugu , Mack, John , Nyokong, Tebello , Zhen, Shen
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186668 , vital:44523 , xlink:href="https://doi.org/10.3390/molecules25163689"
- Description: Two near-infrared (NIR) absorbing di(thien-2-nyl)-di(dimethylanilino)azaBODIPY dyes 2a and 2b were synthesized and characterized that differ depending on whether the dimethylaniline substituents are introduced at the 3,5- or 1,7-positions of the azaBODIPY core. The main spectral bands lie at 824 and 790 nm, respectively, in CH2Cl2. The effect of substituent position on the photophysical and pH sensing properties was analyzed through a comparison of the optical properties with the results of time-dependent density functional theory (TD-DFT) calculations. Protonation of the dimethylamino nitrogen atoms eliminates the intramolecular charge transfer properties of these compounds, and this results in a marked blue-shift of the main absorption bands to 696 and 730 nm, respectively, in CH2Cl2, and a fluorescence “turn-on” effect in the NIR region. The pH dependence studies reveal that the pKa values of the non-protonated 2a and 2b molecules are ca. 6.9 (±0.05) and 7.3 (±0.05), respectively, while that of the monoprotonated species for both dyes is ca. 1.4 (±0.05) making them potentially suitable for use as colorimetric pH indicators under highly acidic conditions.
- Full Text:
- Date Issued: 2020
- Authors: Kubheka, Gugu , Mack, John , Nyokong, Tebello , Zhen, Shen
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186668 , vital:44523 , xlink:href="https://doi.org/10.3390/molecules25163689"
- Description: Two near-infrared (NIR) absorbing di(thien-2-nyl)-di(dimethylanilino)azaBODIPY dyes 2a and 2b were synthesized and characterized that differ depending on whether the dimethylaniline substituents are introduced at the 3,5- or 1,7-positions of the azaBODIPY core. The main spectral bands lie at 824 and 790 nm, respectively, in CH2Cl2. The effect of substituent position on the photophysical and pH sensing properties was analyzed through a comparison of the optical properties with the results of time-dependent density functional theory (TD-DFT) calculations. Protonation of the dimethylamino nitrogen atoms eliminates the intramolecular charge transfer properties of these compounds, and this results in a marked blue-shift of the main absorption bands to 696 and 730 nm, respectively, in CH2Cl2, and a fluorescence “turn-on” effect in the NIR region. The pH dependence studies reveal that the pKa values of the non-protonated 2a and 2b molecules are ca. 6.9 (±0.05) and 7.3 (±0.05), respectively, while that of the monoprotonated species for both dyes is ca. 1.4 (±0.05) making them potentially suitable for use as colorimetric pH indicators under highly acidic conditions.
- Full Text:
- Date Issued: 2020
Nonlinear optical response and electrocatalytic activity of cobalt phthalocyanine clicked zinc oxide nanoparticles
- Mpeta, Lekhetho S, Sekhosana, Kutloano E, Nyokong, Tebello
- Authors: Mpeta, Lekhetho S , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186179 , vital:44471 , xlink:href="https://doi.org/10.1016/j.ica.2020.119661"
- Description: In this article, we report on the linking of cobalt tetrakis (4-pentyn-oxy) phthalocyanine (CoTPPc) to ZnO nanoparticles via click chemistry. Subsequently, electrocatalytic activity and nonlinear optical properties were investigated (the latter using an open Z-scan technique at 532 nm). The linking of CoTPPc with ZnO resulted in the lowest limiting intensity value of 0.27 J.Cm−2, the βeff (cmW−1) values were found to be 1.51 × 10-8 and 7.10 × 104 for ZnO and CoTPPc-ZnO respectively. The catalytic rate constants (M−1s−1) (and limits of detection) were 4.1 × 104 (12.87 µM), 5.7 × 104 (8.62 µM) and 7.36 × 104 (4.35 µM) for ZnO, CoTPPc and CoTPPc-ZnO. Hence linking ZnO nanoparticles to CoTPPc result in the enhancement of both nonlinear optical behaviour and catalytic activity.
- Full Text:
- Date Issued: 2020
- Authors: Mpeta, Lekhetho S , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186179 , vital:44471 , xlink:href="https://doi.org/10.1016/j.ica.2020.119661"
- Description: In this article, we report on the linking of cobalt tetrakis (4-pentyn-oxy) phthalocyanine (CoTPPc) to ZnO nanoparticles via click chemistry. Subsequently, electrocatalytic activity and nonlinear optical properties were investigated (the latter using an open Z-scan technique at 532 nm). The linking of CoTPPc with ZnO resulted in the lowest limiting intensity value of 0.27 J.Cm−2, the βeff (cmW−1) values were found to be 1.51 × 10-8 and 7.10 × 104 for ZnO and CoTPPc-ZnO respectively. The catalytic rate constants (M−1s−1) (and limits of detection) were 4.1 × 104 (12.87 µM), 5.7 × 104 (8.62 µM) and 7.36 × 104 (4.35 µM) for ZnO, CoTPPc and CoTPPc-ZnO. Hence linking ZnO nanoparticles to CoTPPc result in the enhancement of both nonlinear optical behaviour and catalytic activity.
- Full Text:
- Date Issued: 2020
Nutrient-mediated silica uptake from agricultural runoff in invasive floating macrophytes: implications for biological control
- Baso, Nompumelelo C, Delport, Garyn A, Coetzee, Julie A
- Authors: Baso, Nompumelelo C , Delport, Garyn A , Coetzee, Julie A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424803 , vital:72185 , xlink:href="https://doi.org/10.1007/s10750-020-04344-5"
- Description: Silica (Si) plays a significant role in alleviating the effects of biotic and abiotic stressors in many plants, especially in an agricultural context. With increased use of Si-based fertilisers, understanding plant responses to the addition of Si to their environment, particularly aquatic environments, is important. We investigated how two invasive macrophytes, Eichhornia crassipes and Pistia stratiotes, responded to different nutrient and Si concentrations, in the presence and absence of herbivory. Both species incorporated Si into their foliage, but uptake of Si did not increase under high nutrient availability but rather decreased, especially in P. stratiotes. Plant quality (i.e. C:N) for both weed species was affected more by nutrient concentrations than Si content, and the addition of Si had a negative effect on plant growth. Eichhornia crassipes increased daughter plant production under high Si conditions, while P. stratiotes plants showed no reproductive response to increased Si except in low nutrient conditions where reproduction was reduced. The addition of Si resulted in increased biomass of E. crassipes, while P. stratiotes was unaffected. These results highlight that runoff of Si from fertiliser alter aquatic plant–insect interactions, which has consequences for biological control.
- Full Text:
- Date Issued: 2020
- Authors: Baso, Nompumelelo C , Delport, Garyn A , Coetzee, Julie A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424803 , vital:72185 , xlink:href="https://doi.org/10.1007/s10750-020-04344-5"
- Description: Silica (Si) plays a significant role in alleviating the effects of biotic and abiotic stressors in many plants, especially in an agricultural context. With increased use of Si-based fertilisers, understanding plant responses to the addition of Si to their environment, particularly aquatic environments, is important. We investigated how two invasive macrophytes, Eichhornia crassipes and Pistia stratiotes, responded to different nutrient and Si concentrations, in the presence and absence of herbivory. Both species incorporated Si into their foliage, but uptake of Si did not increase under high nutrient availability but rather decreased, especially in P. stratiotes. Plant quality (i.e. C:N) for both weed species was affected more by nutrient concentrations than Si content, and the addition of Si had a negative effect on plant growth. Eichhornia crassipes increased daughter plant production under high Si conditions, while P. stratiotes plants showed no reproductive response to increased Si except in low nutrient conditions where reproduction was reduced. The addition of Si resulted in increased biomass of E. crassipes, while P. stratiotes was unaffected. These results highlight that runoff of Si from fertiliser alter aquatic plant–insect interactions, which has consequences for biological control.
- Full Text:
- Date Issued: 2020
On the move: New insights on the ecology and management of native and alien macrophytes
- Hofstra, Deborah, Schoelynck, Jonas, Ferrell, Jason, Coetzee, Julie A, de Winton, Mary, Bickel, Tobias O, Champion, Paul, Madsen, John, Bakker, Elisabeth S, Hilt, Sabine, Matheson, Fleur, Netherland, Mike, Gross, Elisabeth M
- Authors: Hofstra, Deborah , Schoelynck, Jonas , Ferrell, Jason , Coetzee, Julie A , de Winton, Mary , Bickel, Tobias O , Champion, Paul , Madsen, John , Bakker, Elisabeth S , Hilt, Sabine , Matheson, Fleur , Netherland, Mike , Gross, Elisabeth M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419346 , vital:71636 , xlink:href=" https://doi.org/10.1016/j.aquabot.2019.103190"
- Description: Globally, freshwater ecosystems are under threat. The main threats come from catchment land-use changes, altered water regimes, eutrophication, invasive species, climate change and combinations of these factors. We need scientific research to respond to these challenges by providing solutions to halt the deterioration and improve the condition of our valuable freshwaters. This requires a good understanding of aquatic ecosystems, and the nature and scale of changes occurring. Macrophytes play a fundamental role in aquatic systems. They are sensitive indicators of ecosystem health, as they are affected by run-off from agricultural, industrial or urban areas. On the other hand, alien macrophytes are increasingly invading aquatic systems all over the world. Improving our knowledge on the ecology and management of both native and alien plants is indispensable to address threats to freshwaters in order to protect and restore aquatic habitats. The International Aquatic Plants Group (IAPG) brings together scientists and practitioners based at universities, research and environmental organisations around the world. The main themes of the 15th symposium 2018 in New Zealand were biodiversity and conservation, management, invasive species, and ecosystem response and restoration. This Virtual Special Issue provides a comprehensive review from the symposium, addressing the ecology of native macrophytes, including those of conservation concern, and highly invasive alien macrophytes, and the implications of management interventions. In this editorial paper, we highlight insights and paradigms on the ecology and management of native and alien macrophytes gathered during the meeting.
- Full Text:
- Date Issued: 2020
- Authors: Hofstra, Deborah , Schoelynck, Jonas , Ferrell, Jason , Coetzee, Julie A , de Winton, Mary , Bickel, Tobias O , Champion, Paul , Madsen, John , Bakker, Elisabeth S , Hilt, Sabine , Matheson, Fleur , Netherland, Mike , Gross, Elisabeth M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419346 , vital:71636 , xlink:href=" https://doi.org/10.1016/j.aquabot.2019.103190"
- Description: Globally, freshwater ecosystems are under threat. The main threats come from catchment land-use changes, altered water regimes, eutrophication, invasive species, climate change and combinations of these factors. We need scientific research to respond to these challenges by providing solutions to halt the deterioration and improve the condition of our valuable freshwaters. This requires a good understanding of aquatic ecosystems, and the nature and scale of changes occurring. Macrophytes play a fundamental role in aquatic systems. They are sensitive indicators of ecosystem health, as they are affected by run-off from agricultural, industrial or urban areas. On the other hand, alien macrophytes are increasingly invading aquatic systems all over the world. Improving our knowledge on the ecology and management of both native and alien plants is indispensable to address threats to freshwaters in order to protect and restore aquatic habitats. The International Aquatic Plants Group (IAPG) brings together scientists and practitioners based at universities, research and environmental organisations around the world. The main themes of the 15th symposium 2018 in New Zealand were biodiversity and conservation, management, invasive species, and ecosystem response and restoration. This Virtual Special Issue provides a comprehensive review from the symposium, addressing the ecology of native macrophytes, including those of conservation concern, and highly invasive alien macrophytes, and the implications of management interventions. In this editorial paper, we highlight insights and paradigms on the ecology and management of native and alien macrophytes gathered during the meeting.
- Full Text:
- Date Issued: 2020
Optical limiting properties of D-π-A BODIPY dyes in the presence and absence of methyl groups at the 1, 7-positions
- May, Aviwe K, Mack, John, Nyokong, Tebello
- Authors: May, Aviwe K , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186146 , vital:44468 , xlink:href="https://doi.org/10.1142/S1088424620500315"
- Description: The optical limiting properties of three meso-pentafluorophenylstyrylBODIPY dyes are investigated in the presence and absence of methyl groups at the 1,7-positions that hinder free rotation of the meso-aryl group. Pentafluorophenyl groups are introduced at the meso-position, while 4-diethylaminostyryl groups are introduced at the 3- and/or 5-positions to form dyes with strong donor-ππ-acceptor (D-ππ-A) properties to enhance the dipole moment of the molecule. Favorable optical limiting properties are obtained for all three dyes, with the highest second-order hyperpolarizability value obtained for a monostyryl dye with no methyl groups at the 1,7-position. Bromination at the 2,6-positions of a 1,7-methyl substituted dye is found to result in second-order hyperpolarizability that is an order of magnitude lower than that calculated for the analogous non-halogenated dye.
- Full Text:
- Date Issued: 2020
- Authors: May, Aviwe K , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186146 , vital:44468 , xlink:href="https://doi.org/10.1142/S1088424620500315"
- Description: The optical limiting properties of three meso-pentafluorophenylstyrylBODIPY dyes are investigated in the presence and absence of methyl groups at the 1,7-positions that hinder free rotation of the meso-aryl group. Pentafluorophenyl groups are introduced at the meso-position, while 4-diethylaminostyryl groups are introduced at the 3- and/or 5-positions to form dyes with strong donor-ππ-acceptor (D-ππ-A) properties to enhance the dipole moment of the molecule. Favorable optical limiting properties are obtained for all three dyes, with the highest second-order hyperpolarizability value obtained for a monostyryl dye with no methyl groups at the 1,7-position. Bromination at the 2,6-positions of a 1,7-methyl substituted dye is found to result in second-order hyperpolarizability that is an order of magnitude lower than that calculated for the analogous non-halogenated dye.
- Full Text:
- Date Issued: 2020
Optical limiting properties of indium 5, 10, 15, 20-tetrakis (4-aminophenyl) porphyrin covalently linked to semiconductor quantum dots
- Managa, Muthumuni, Mgidlana, Sithi, Khene, Samson M, Nyokong, Tebello
- Authors: Managa, Muthumuni , Mgidlana, Sithi , Khene, Samson M , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186101 , vital:44463 , xlink:href="https://doi.org/10.1016/j.ica.2020.119838"
- Description: 5,10,15,20-tetrakis(4-aminophenyl) porphyrin and it indium derivative were synthesised and characterized then covalently linked to CdTe/ZnSe/ZnO semiconductor quantum dots. The nonlinear absorption of the complexes was studied using the Z-scan technique at 532 nm and 10 ns pulse in dimethyl sulfoxide. Indium 5,10,15,20- tetrakis(4-aminophenyl) porphyrin (InTAPP) exhibited the strongest nonlinear optical behaviour in comparison with the metal free derivative. DFT calculations were carried out using SDD basis set at B3LYP level of theory. The nonlinear absorption coefficient (βeff) values were determined experimentally using Z-scan whereby the first static hyperpolarizability (βHRS) value were determined using DFT calcutions.
- Full Text:
- Date Issued: 2020
- Authors: Managa, Muthumuni , Mgidlana, Sithi , Khene, Samson M , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186101 , vital:44463 , xlink:href="https://doi.org/10.1016/j.ica.2020.119838"
- Description: 5,10,15,20-tetrakis(4-aminophenyl) porphyrin and it indium derivative were synthesised and characterized then covalently linked to CdTe/ZnSe/ZnO semiconductor quantum dots. The nonlinear absorption of the complexes was studied using the Z-scan technique at 532 nm and 10 ns pulse in dimethyl sulfoxide. Indium 5,10,15,20- tetrakis(4-aminophenyl) porphyrin (InTAPP) exhibited the strongest nonlinear optical behaviour in comparison with the metal free derivative. DFT calculations were carried out using SDD basis set at B3LYP level of theory. The nonlinear absorption coefficient (βeff) values were determined experimentally using Z-scan whereby the first static hyperpolarizability (βHRS) value were determined using DFT calcutions.
- Full Text:
- Date Issued: 2020
Oral Phytothymol ameliorates the stress induced IBS symptoms
- Subramaniyam, Selvaraj, Yang, Shuyou, Diallo, Bakary N, Fanshu, Xu, Lei, Luo, Li, Chong, Tastan-Bishop, Özlem, Bhattacharyya, Sanjib
- Authors: Subramaniyam, Selvaraj , Yang, Shuyou , Diallo, Bakary N , Fanshu, Xu , Lei, Luo , Li, Chong , Tastan-Bishop, Özlem , Bhattacharyya, Sanjib
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426034 , vital:72308 , xlink:href="https://doi.org/10.1038/s41598-020-70420-4"
- Description: Physical stressors play a crucial role in the progression of irritable bowel syndrome (IBS). Here we report a heterogeneous physical stress induced IBS rat model which shows depression and subsequent modulation of IBS by oral treatment of thymol. Oral administration of Thymol reduces the stress induced IBS significantly altering the stress induced gastrointestinal hypermotility, prolonged the whole gut transit time, and increased abdominal withdrawal reflex suggesting gastrointestinal hypermotility and visceral discomfort caused the onset of depression. Immunohistochemical analysis in small intestine and colon of rats shows the decreased 5-HT3AR expression level while thymol treatment normalized the 5-HT3AR expression in the stressed rats. Molecular docking studies showed that thymol competes with endogenous serotonin and an antagonist, Tropisetron and all have similar binding energies to 5-HT3AR. Molecular dynamics simulations revealed that thymol and tropisetron might have similar effects on 5-HT3AR. Our study suggest that thymol improves IBS symptoms through 5-HT3AR, could be useful for the treatment of IBS.
- Full Text:
- Date Issued: 2020
- Authors: Subramaniyam, Selvaraj , Yang, Shuyou , Diallo, Bakary N , Fanshu, Xu , Lei, Luo , Li, Chong , Tastan-Bishop, Özlem , Bhattacharyya, Sanjib
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426034 , vital:72308 , xlink:href="https://doi.org/10.1038/s41598-020-70420-4"
- Description: Physical stressors play a crucial role in the progression of irritable bowel syndrome (IBS). Here we report a heterogeneous physical stress induced IBS rat model which shows depression and subsequent modulation of IBS by oral treatment of thymol. Oral administration of Thymol reduces the stress induced IBS significantly altering the stress induced gastrointestinal hypermotility, prolonged the whole gut transit time, and increased abdominal withdrawal reflex suggesting gastrointestinal hypermotility and visceral discomfort caused the onset of depression. Immunohistochemical analysis in small intestine and colon of rats shows the decreased 5-HT3AR expression level while thymol treatment normalized the 5-HT3AR expression in the stressed rats. Molecular docking studies showed that thymol competes with endogenous serotonin and an antagonist, Tropisetron and all have similar binding energies to 5-HT3AR. Molecular dynamics simulations revealed that thymol and tropisetron might have similar effects on 5-HT3AR. Our study suggest that thymol improves IBS symptoms through 5-HT3AR, could be useful for the treatment of IBS.
- Full Text:
- Date Issued: 2020
Paul Ashwin Transforming university education, a manifesto: A review
- Authors: McKenna, Sioux
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185886 , vital:44445 , xlink:href="https://doi.org/10.1007/s10734-020-00641-z"
- Description: This book is wide-ranging in its focus. It tackles student-centeredness, graduate premiums, credentialing, quality assurance, big data and rankings, and yet it offers a coherent engagement with these and many other contemporary issues. The coherence is brought about by the consistent application of one central idea throughout the book. That is that the value of higher education for both the individual and for society is that it brings the graduate into a transformational relationship with knowledge that changes their sense of who they are and thereby makes possible their doing all number of things in the world.
- Full Text:
- Date Issued: 2020
- Authors: McKenna, Sioux
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185886 , vital:44445 , xlink:href="https://doi.org/10.1007/s10734-020-00641-z"
- Description: This book is wide-ranging in its focus. It tackles student-centeredness, graduate premiums, credentialing, quality assurance, big data and rankings, and yet it offers a coherent engagement with these and many other contemporary issues. The coherence is brought about by the consistent application of one central idea throughout the book. That is that the value of higher education for both the individual and for society is that it brings the graduate into a transformational relationship with knowledge that changes their sense of who they are and thereby makes possible their doing all number of things in the world.
- Full Text:
- Date Issued: 2020
Perceived benefits of nature-based experiences as mediators of connectedness with nature: The case of Mystic Mountain
- Ward-Smith, Chesney, Naidoo, Tony, Olvitt, Lausanne L, Olvitt, Lausanne, Akhurst, Jacqueline
- Authors: Ward-Smith, Chesney , Naidoo, Tony , Olvitt, Lausanne L , Olvitt, Lausanne , Akhurst, Jacqueline
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/372782 , vital:66622 , xlink:href="https://doi.org/10.1177/00812463209470"
- Description: Perceived nature disconnection lies at the heart of the world’s socio-ecological crisis. Finding ways to reconnect with nature is fundamental towards reducing the adverse psychological–social– ecological consequences of this disconnection. Understanding the psychological and social benefits of nature-based experiences is important towards actualising reconnection. This article discusses such benefits for child and adult participants from the Eastern Cape, South Africa. This work stems from Ecopsychology research with an outdoor education centre, Mystic Mountain. The experiences of two groups of children (n=25, aged 10–14years) and adult instructors (n=12, aged 18–50years) were explored using interpretive case-study methodology. Through semi-structured interviews and focus groups, participant observation, and reflexive journaling, data were collected and analysed thematically. This article centralises participants’ perceived psychological and social benefits of nature-based experiences as mediators of deeper self and nature connectedness. Integrating these benefits into nature-based pedagogy-design processes could contribute towards more effective enhancements of nature connectedness, and in turn, foster Earth’s larger flourishment.
- Full Text:
- Date Issued: 2020
- Authors: Ward-Smith, Chesney , Naidoo, Tony , Olvitt, Lausanne L , Olvitt, Lausanne , Akhurst, Jacqueline
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/372782 , vital:66622 , xlink:href="https://doi.org/10.1177/00812463209470"
- Description: Perceived nature disconnection lies at the heart of the world’s socio-ecological crisis. Finding ways to reconnect with nature is fundamental towards reducing the adverse psychological–social– ecological consequences of this disconnection. Understanding the psychological and social benefits of nature-based experiences is important towards actualising reconnection. This article discusses such benefits for child and adult participants from the Eastern Cape, South Africa. This work stems from Ecopsychology research with an outdoor education centre, Mystic Mountain. The experiences of two groups of children (n=25, aged 10–14years) and adult instructors (n=12, aged 18–50years) were explored using interpretive case-study methodology. Through semi-structured interviews and focus groups, participant observation, and reflexive journaling, data were collected and analysed thematically. This article centralises participants’ perceived psychological and social benefits of nature-based experiences as mediators of deeper self and nature connectedness. Integrating these benefits into nature-based pedagogy-design processes could contribute towards more effective enhancements of nature connectedness, and in turn, foster Earth’s larger flourishment.
- Full Text:
- Date Issued: 2020
Photodynamic activity of 2, 6-diiodo-3, 5-dithienylvinyleneBODIPYs and their folate-functionalized chitosan-coated Pluronic® F-127 micelles on MCF-7 breast cancer cells
- Molupe, Nthabeleng, Babu, Balaji, Oluwole, David O, Prinsloo, Earl, Gai, Lizhi, Shen, Zhen, Mack, John, Nyokong, Tebello
- Authors: Molupe, Nthabeleng , Babu, Balaji , Oluwole, David O , Prinsloo, Earl , Gai, Lizhi , Shen, Zhen , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186222 , vital:44474 , xlink:href="https://doi.org/10.1142/S1088424619501773"
- Description: A 2,6-diiodo-3,5-dithienylvinyleneBODIPY dye was prepared and encapsulated with folate-chitosan capped Pluronic®® F-127 to provide drug delivery systems for photodynamic therapy (PDT). Moderately enhanced singlet oxygen quantum yields were observed for the dye encapsulation complexes in water. The in vitro dark cytotoxicity and photodynamic activity were investigated on the human breast adenocarcinoma (MCF-7) cell line. Minimal dark cytotoxicity was observed for the BODIPY dyes in 5% DMSO and when encapsulated in folate-functionalized chitosan-coated Pluronic®® F-127 micelles, since the cell viability values are consistently greater than 80% over the 0-40 μg⋅mL−1μg⋅mL−1 concentration range. Upon irradiation of the samples, significant cytocidal activity was observed for the encapsulation complex of a 2,6-diiodo-8-dimethylaminophenyl-3,5-dithienylvinyleneBODIPY dye with less than 50% viable cells observed at concentrations ≥20μg⋅mL−1≥20μg⋅mL−1.
- Full Text:
- Date Issued: 2020
- Authors: Molupe, Nthabeleng , Babu, Balaji , Oluwole, David O , Prinsloo, Earl , Gai, Lizhi , Shen, Zhen , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186222 , vital:44474 , xlink:href="https://doi.org/10.1142/S1088424619501773"
- Description: A 2,6-diiodo-3,5-dithienylvinyleneBODIPY dye was prepared and encapsulated with folate-chitosan capped Pluronic®® F-127 to provide drug delivery systems for photodynamic therapy (PDT). Moderately enhanced singlet oxygen quantum yields were observed for the dye encapsulation complexes in water. The in vitro dark cytotoxicity and photodynamic activity were investigated on the human breast adenocarcinoma (MCF-7) cell line. Minimal dark cytotoxicity was observed for the BODIPY dyes in 5% DMSO and when encapsulated in folate-functionalized chitosan-coated Pluronic®® F-127 micelles, since the cell viability values are consistently greater than 80% over the 0-40 μg⋅mL−1μg⋅mL−1 concentration range. Upon irradiation of the samples, significant cytocidal activity was observed for the encapsulation complex of a 2,6-diiodo-8-dimethylaminophenyl-3,5-dithienylvinyleneBODIPY dye with less than 50% viable cells observed at concentrations ≥20μg⋅mL−1≥20μg⋅mL−1.
- Full Text:
- Date Issued: 2020
Photodynamic antimicrobial chemotherapy of a dimethylamino-functionalized asymmetric zinc (II) phthalocyanine and its quaternized derivative against Staphylococcus aureus when supported on asymmetric polystyrene polymer membranes
- Mafukidze, Donovan M, Nyokong, Tebello
- Authors: Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186168 , vital:44470 , xlink:href="https://doi.org/10.1016/j.reactfunctpolym.2020.104634"
- Description: Membrane applications are hindered by fouling. Photoactive membranes (containing photosensitizers) show photodynamic antimicrobial chemotherapy (PACT) activity which reduces biological fouling. In this work we use phthalocyanines (Pcs) as photosensitizers. The Pcs used are: 2-(4-carboxyphenoxy)-9(10), 16(17), 23(24)-tris(dimethylamino) phthalocyaninato zinc(II) (1) and the quaternized 2-(4-carboxyphenoxy)-9(10), 16(17), 23(24)-tris(trimethylamino) phthalocyanine zinc(II) methyl sulfate (2). Complex 2 showed an enhanced singlet oxygen quantum yield (ΦΔ) of 0.76 compared to 0.53 for 1. Complex 2 showed enhanced PACT activity against Staphylococcus aureus giving a log reduction value of 9.4, while its precursor (complex 1) gave 0.08. The complexes were then conjugated to amine-functionalized polystyrene and embedded into polystyrene to form membranes resulting in ΦΔ values of 0.24 and 0.27 for complexes 1 and 2 respectively in water. The latter membrane showed better PACT activity.
- Full Text:
- Date Issued: 2020
- Authors: Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186168 , vital:44470 , xlink:href="https://doi.org/10.1016/j.reactfunctpolym.2020.104634"
- Description: Membrane applications are hindered by fouling. Photoactive membranes (containing photosensitizers) show photodynamic antimicrobial chemotherapy (PACT) activity which reduces biological fouling. In this work we use phthalocyanines (Pcs) as photosensitizers. The Pcs used are: 2-(4-carboxyphenoxy)-9(10), 16(17), 23(24)-tris(dimethylamino) phthalocyaninato zinc(II) (1) and the quaternized 2-(4-carboxyphenoxy)-9(10), 16(17), 23(24)-tris(trimethylamino) phthalocyanine zinc(II) methyl sulfate (2). Complex 2 showed an enhanced singlet oxygen quantum yield (ΦΔ) of 0.76 compared to 0.53 for 1. Complex 2 showed enhanced PACT activity against Staphylococcus aureus giving a log reduction value of 9.4, while its precursor (complex 1) gave 0.08. The complexes were then conjugated to amine-functionalized polystyrene and embedded into polystyrene to form membranes resulting in ΦΔ values of 0.24 and 0.27 for complexes 1 and 2 respectively in water. The latter membrane showed better PACT activity.
- Full Text:
- Date Issued: 2020
Photodynamic antimicrobial chemotherapy of asymmetric porphyrin-silver conjugates towards photoinactivation of Staphylococcus aureus
- Shabangu, Samuel M, Babu, Balaji, Soy, Rodah C, Managa, Muthumuni, Sekhosana, Kutloano E, Nyokong, Tebello
- Authors: Shabangu, Samuel M , Babu, Balaji , Soy, Rodah C , Managa, Muthumuni , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186536 , vital:44509 , xlink:href="https://doi.org/10.1080/00958972.2020.1739273"
- Description: Asymmetric mono-carboxy-porphyrins, (5-(4-carboxyphenyl)10,15, 20-tris(pentafluorophenyl)porphyrinato zinc(II) (1), 5-(4- carboxyphenyl)10,15,20-triphenylporphyrinato zinc(II) (2) and 5-(4- carboxyphenyl)10,15,20-tris(2-thienyl)porphyrinato zinc(II) (3), were linked to Ag nanoparticles (AgNPs) through amide bonds and selfassembly (the latter only for 3). The porphyrins and conjugates were used for photodynamic antimicrobial chemotherapy (PACT) against Staphylococcus aureus. PACT uses singlet oxygen for antimicrobial activity. Complex 3 and its conjugates had higher singlet oxygen quantum yields and higher log reduction when compared with the rest of the porphyrins and corresponding conjugates. These high log reductions for 3 and its conjugate were attributed to the presence of sulfur groups whereby there was more interaction with the bacterial membrane.
- Full Text:
- Date Issued: 2020
- Authors: Shabangu, Samuel M , Babu, Balaji , Soy, Rodah C , Managa, Muthumuni , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186536 , vital:44509 , xlink:href="https://doi.org/10.1080/00958972.2020.1739273"
- Description: Asymmetric mono-carboxy-porphyrins, (5-(4-carboxyphenyl)10,15, 20-tris(pentafluorophenyl)porphyrinato zinc(II) (1), 5-(4- carboxyphenyl)10,15,20-triphenylporphyrinato zinc(II) (2) and 5-(4- carboxyphenyl)10,15,20-tris(2-thienyl)porphyrinato zinc(II) (3), were linked to Ag nanoparticles (AgNPs) through amide bonds and selfassembly (the latter only for 3). The porphyrins and conjugates were used for photodynamic antimicrobial chemotherapy (PACT) against Staphylococcus aureus. PACT uses singlet oxygen for antimicrobial activity. Complex 3 and its conjugates had higher singlet oxygen quantum yields and higher log reduction when compared with the rest of the porphyrins and corresponding conjugates. These high log reductions for 3 and its conjugate were attributed to the presence of sulfur groups whereby there was more interaction with the bacterial membrane.
- Full Text:
- Date Issued: 2020
Photophysical and nonlinear optical properties of the positional isomers of 4-(4-tertbutylphenoxy) substituted cobalt, nickel and copper phthalocyanines
- Neduvhuledza, Zelda, Nkaki, Thabo, Louzada, Marcel, Nyokong, Tebello, Khene, Samson M
- Authors: Neduvhuledza, Zelda , Nkaki, Thabo , Louzada, Marcel , Nyokong, Tebello , Khene, Samson M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186067 , vital:44460 , xlink:href="https://doi.org/10.1016/j.optmat.2020.110195"
- Description: This paper reports on the third order nonlinear optical properties of cobalt, nickel and tetrakis(4- terbutylphenoxy)phthalocyaninatocopper(II) isomers, using the Z-scan technique. Metal-free isomers were found to have high nonlinear absorption coefficient (β) values compared to the metalated isomers. Metal-free C2v isomer was found to have the highest β value of 1.52 × 10− 10 mMW− 1 in THF. All the metal-free and metal phthalocyanine isomers nonlinear properties were found to be dependent on the singlet state absorption. Imaginary second order nonlinear hyperpolarizability (Im[γ]), ground state cross section (σg), excited states cross sections (σs and σt) and two photon absorption (TPA) cross section (σTPA) values are reported in this work. The five-energy level model rate equations were used to model the nonlinear response and absorption cross sections.
- Full Text:
- Date Issued: 2020
- Authors: Neduvhuledza, Zelda , Nkaki, Thabo , Louzada, Marcel , Nyokong, Tebello , Khene, Samson M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186067 , vital:44460 , xlink:href="https://doi.org/10.1016/j.optmat.2020.110195"
- Description: This paper reports on the third order nonlinear optical properties of cobalt, nickel and tetrakis(4- terbutylphenoxy)phthalocyaninatocopper(II) isomers, using the Z-scan technique. Metal-free isomers were found to have high nonlinear absorption coefficient (β) values compared to the metalated isomers. Metal-free C2v isomer was found to have the highest β value of 1.52 × 10− 10 mMW− 1 in THF. All the metal-free and metal phthalocyanine isomers nonlinear properties were found to be dependent on the singlet state absorption. Imaginary second order nonlinear hyperpolarizability (Im[γ]), ground state cross section (σg), excited states cross sections (σs and σt) and two photon absorption (TPA) cross section (σTPA) values are reported in this work. The five-energy level model rate equations were used to model the nonlinear response and absorption cross sections.
- Full Text:
- Date Issued: 2020
Photophysico-chemical properties and photoinactivation of Staphylococcus Aureus using zinc phthalocyanines linked silver nanoparticles conjugates
- Matlou, Gauta G, Nyokong, Tebello
- Authors: Matlou, Gauta G , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186278 , vital:44481 , xlink:href="https://doi.org/10.1016/j.dyepig.2020.108237"
- Description: The synthesis of zinc (II) tri (tert-butyl phenoxy) mono cinnamic acid Pc (complex 1) is reported for the first time in this work. Complex 1 and the reported zinc (II) tri (tert-butyl), mono cinnamic acid phthalocyanine (2), zinc (II) mono cinnamic acid substituted phthalocyanine (3) and zinc (II) tetra cinnamic acid substituted phthalocyanine (4) are conjugated to cysteine capped silver nanoparticles (cys-AgNPs) through an amide bond. The photophysicochemical properties and the photodynamic antimicrobial chemotherapy (PACT) activities of the Pc-cys-AgNPs conjugates and the Pcs alone on S. Aureus are reported. Improved triplet and singlet oxygen quantum yields were observed for the conjugated complexes compared to Pcs alone, due to the heavy atom effect of cys-AgNPs. Asymmetric complexes 1,2, 3 and their respective conjugates recorded higher photosensitizing properties and PACT activities compared to 4 and 4-cys-AgNPs, respectively. Higher log reductions and percentage reductions of S. Aureus were recorded for conjugated complexes compared to ZnPcs only, showing enhanced PACT activities due to their higher singlet oxygen quantum yields.
- Full Text:
- Date Issued: 2020
- Authors: Matlou, Gauta G , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186278 , vital:44481 , xlink:href="https://doi.org/10.1016/j.dyepig.2020.108237"
- Description: The synthesis of zinc (II) tri (tert-butyl phenoxy) mono cinnamic acid Pc (complex 1) is reported for the first time in this work. Complex 1 and the reported zinc (II) tri (tert-butyl), mono cinnamic acid phthalocyanine (2), zinc (II) mono cinnamic acid substituted phthalocyanine (3) and zinc (II) tetra cinnamic acid substituted phthalocyanine (4) are conjugated to cysteine capped silver nanoparticles (cys-AgNPs) through an amide bond. The photophysicochemical properties and the photodynamic antimicrobial chemotherapy (PACT) activities of the Pc-cys-AgNPs conjugates and the Pcs alone on S. Aureus are reported. Improved triplet and singlet oxygen quantum yields were observed for the conjugated complexes compared to Pcs alone, due to the heavy atom effect of cys-AgNPs. Asymmetric complexes 1,2, 3 and their respective conjugates recorded higher photosensitizing properties and PACT activities compared to 4 and 4-cys-AgNPs, respectively. Higher log reductions and percentage reductions of S. Aureus were recorded for conjugated complexes compared to ZnPcs only, showing enhanced PACT activities due to their higher singlet oxygen quantum yields.
- Full Text:
- Date Issued: 2020
Plant-Based Synthesis of Silver Nanoparticles Using Aqueous Leaf Extract of Salvia officinalis: Characterization and its Antiplasmodial Activity
- Okaiyeto, Kunle, Hoppe, Heinrich, Okoh, Anthony I
- Authors: Okaiyeto, Kunle , Hoppe, Heinrich , Okoh, Anthony I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429472 , vital:72613 , xlink:href="https://doi.org/10.1007/s10876-020-01766-y"
- Description: In the present study, an aqueous leaf extract of Salvia officinalis was used to synthesize silver nanoparticles (AgNPs) and characterized with different techniques such as UV–vis spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDX), Transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Subsequently, its cytotoxic effect against human cervix adenocarcinoma (HeLa) cells and antiplasmodial activity against Plasmodium falciparum were investigated. UV–vis spectrum of AgNPs displayed an absorption peak at 323 nm and TEM result revealed it to be spherical in shape with average size of 41 nm. FTIR results highlighted the key bioactive compounds that could be responsible for the reduction and capping of AgNPs and XRD analysis showed its crystalline nature with a face-centered cubic (fcc) structure. The synthesized AgNPs was found to be less cytotoxic against HeLa cells line and demonstrated good antiplasmodial potential (IC50 = 3.6 µg/mL). Findings from this study indicated that the AgNPs could serve as a template in the development of new drugs for the control of malaria and hence, further study is needed to identify and characterize the potent molecules that suppress the malaria parasite.
- Full Text:
- Date Issued: 2020
- Authors: Okaiyeto, Kunle , Hoppe, Heinrich , Okoh, Anthony I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429472 , vital:72613 , xlink:href="https://doi.org/10.1007/s10876-020-01766-y"
- Description: In the present study, an aqueous leaf extract of Salvia officinalis was used to synthesize silver nanoparticles (AgNPs) and characterized with different techniques such as UV–vis spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDX), Transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Subsequently, its cytotoxic effect against human cervix adenocarcinoma (HeLa) cells and antiplasmodial activity against Plasmodium falciparum were investigated. UV–vis spectrum of AgNPs displayed an absorption peak at 323 nm and TEM result revealed it to be spherical in shape with average size of 41 nm. FTIR results highlighted the key bioactive compounds that could be responsible for the reduction and capping of AgNPs and XRD analysis showed its crystalline nature with a face-centered cubic (fcc) structure. The synthesized AgNPs was found to be less cytotoxic against HeLa cells line and demonstrated good antiplasmodial potential (IC50 = 3.6 µg/mL). Findings from this study indicated that the AgNPs could serve as a template in the development of new drugs for the control of malaria and hence, further study is needed to identify and characterize the potent molecules that suppress the malaria parasite.
- Full Text:
- Date Issued: 2020