Three new biological control programmes for South Africa: Brazilian pepper, Tamarix and Tradescantia
- Byrne, Marcus J, Mayonde, Samalesu, Venter, Nic, Chidawanyika, Frank, Zachariades, Coates, Martin, Grant D
- Authors: Byrne, Marcus J , Mayonde, Samalesu , Venter, Nic , Chidawanyika, Frank , Zachariades, Coates , Martin, Grant D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414490 , vital:71152 , xlink:href="https://hdl.handle.net/10520/ejc-cristal-v10-n1-a7"
- Description: Three weed biological control (biocontrol) programmes are described, all of which are considered to be ‘transfer projects’ that were initiated elsewhere, and on which South Africa has piggybacked its biocontrol efforts. Using knowledge and expertise from international collaborators, South African weed researchers are following a long tradition of transfer projects, which has been a largely successful and practical approach to biocontrol. Two Brazilian weeds, the Brazilian pepper tree Schinus terebinthifolia and the spiderwort Tradescantia fluminensis are being targeted, along with the Old-World trees Tamarix ramosissima and T. chinensis. The potential biocontrol agents are described and ranked for the two trees according to what has been discovered elsewhere, while the agent already released against T. fluminensis is rated (as poor), and other potential agents are considered. The addition of molecular techniques, climate matching and remote sensing in transfer projects can increase the chance of successful biocontrol and the inclusion of these techniques in the three new programmes is discussed. Transfer projects are a cost-effective and pragmatic way to pick winning biocontrol programmes.
- Full Text:
- Date Issued: 2021
Three new biological control programmes for South Africa: Brazilian pepper, Tamarix and Tradescantia
- Authors: Byrne, Marcus J , Mayonde, Samalesu , Venter, Nic , Chidawanyika, Frank , Zachariades, Coates , Martin, Grant D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414490 , vital:71152 , xlink:href="https://hdl.handle.net/10520/ejc-cristal-v10-n1-a7"
- Description: Three weed biological control (biocontrol) programmes are described, all of which are considered to be ‘transfer projects’ that were initiated elsewhere, and on which South Africa has piggybacked its biocontrol efforts. Using knowledge and expertise from international collaborators, South African weed researchers are following a long tradition of transfer projects, which has been a largely successful and practical approach to biocontrol. Two Brazilian weeds, the Brazilian pepper tree Schinus terebinthifolia and the spiderwort Tradescantia fluminensis are being targeted, along with the Old-World trees Tamarix ramosissima and T. chinensis. The potential biocontrol agents are described and ranked for the two trees according to what has been discovered elsewhere, while the agent already released against T. fluminensis is rated (as poor), and other potential agents are considered. The addition of molecular techniques, climate matching and remote sensing in transfer projects can increase the chance of successful biocontrol and the inclusion of these techniques in the three new programmes is discussed. Transfer projects are a cost-effective and pragmatic way to pick winning biocontrol programmes.
- Full Text:
- Date Issued: 2021
Top-Down Synthesis of a Lamivudine-Zidovudine Nano Co-Crystal
- Witika, Bwalya A, Smith, Vincent J, Walker, Roderick B
- Authors: Witika, Bwalya A , Smith, Vincent J , Walker, Roderick B
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183172 , vital:43918 , xlink:href="https://doi.org/10.3390/cryst11010033"
- Description: Lamivudine (3TC) and zidovudine (AZT) are antiretroviral agents used to manage HIV/AIDS infection. A wet media milling top-down approach was used to develop and produce nano co-crystals of 3TC and AZT. Micro co-crystals were prepared by solvent evaporation and subsequently milled in the presence of two surfactants, viz., sodium lauryl sulfate (SLS) and α-tocopheryl polyethylene glycol succinate 1000 (TPGS 1000). Optimisation was undertaken using design of experiments (DoE) and response surface methodology (RSM) to establish and identify parameters that may affect the manufacturing of nano co-crystals. The impact of SLS and TPGS 1000 concentration, milling time, and number of units of milling medium on the manufacturing of nano co-crystals, was investigated. The critical quality attributes (CQA) monitored were particle size (PS), Zeta potential (ZP), and polydispersity index (PDI). Powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, transmission electron microscopy, energy dispersive X-ray spectroscopy scanning electron microscopy, and cytotoxicity assays were used for additional characterization of the optimised nano co-crystal. The mean PS, PDI, and ZP of the optimised top-down nanocrystal were 271.0 ± 92.0 nm, 0.467 ± 0.073, and −41.9 ± 3.94 mV, respectively. In conclusion, a simple, inexpensive, rapid, and precise method of nano co-crystal manufacturing was developed, validated, and optimised using DoE and RSM, and the final product exhibited the target CQA.
- Full Text:
- Date Issued: 2021
- Authors: Witika, Bwalya A , Smith, Vincent J , Walker, Roderick B
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183172 , vital:43918 , xlink:href="https://doi.org/10.3390/cryst11010033"
- Description: Lamivudine (3TC) and zidovudine (AZT) are antiretroviral agents used to manage HIV/AIDS infection. A wet media milling top-down approach was used to develop and produce nano co-crystals of 3TC and AZT. Micro co-crystals were prepared by solvent evaporation and subsequently milled in the presence of two surfactants, viz., sodium lauryl sulfate (SLS) and α-tocopheryl polyethylene glycol succinate 1000 (TPGS 1000). Optimisation was undertaken using design of experiments (DoE) and response surface methodology (RSM) to establish and identify parameters that may affect the manufacturing of nano co-crystals. The impact of SLS and TPGS 1000 concentration, milling time, and number of units of milling medium on the manufacturing of nano co-crystals, was investigated. The critical quality attributes (CQA) monitored were particle size (PS), Zeta potential (ZP), and polydispersity index (PDI). Powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, transmission electron microscopy, energy dispersive X-ray spectroscopy scanning electron microscopy, and cytotoxicity assays were used for additional characterization of the optimised nano co-crystal. The mean PS, PDI, and ZP of the optimised top-down nanocrystal were 271.0 ± 92.0 nm, 0.467 ± 0.073, and −41.9 ± 3.94 mV, respectively. In conclusion, a simple, inexpensive, rapid, and precise method of nano co-crystal manufacturing was developed, validated, and optimised using DoE and RSM, and the final product exhibited the target CQA.
- Full Text:
- Date Issued: 2021
Towards The Quantification Of The Historical And Future Water Resources Of The Limpopo River
- Kapangaziwiri, Evison, Kahinda, Jean-Marc M, Oosthuizen, Nadia, Mvandaba, Vuyelwa, Hobbs, Philip, Hughes, Denis A
- Authors: Kapangaziwiri, Evison , Kahinda, Jean-Marc M , Oosthuizen, Nadia , Mvandaba, Vuyelwa , Hobbs, Philip , Hughes, Denis A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438349 , vital:73453 , ISBN 978-0-6392-0303-4 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2439_final.pdf
- Description: The complexity of current water resource management poses many challenges. Wa-ter managers must solve a range of interrelated dilemmas – such as balancing quan-tity and quality, mitigating the effects of flooding and drought, and maintaining bio-diversity, ecological functions, and services. Sustainable water resource manage-ment, planning, and development requires reliable quantification of the amount, distribution, and quality of water within river basins. With the demand for water resources rapidly growing across the globe, there is also an urgent need for accu-rate monitoring, forecasting and simulation of hydrologic variables – especially in major (often transboundary) river basins such as the Limpopo – not only for optimal water resources management but more compellingly, also for water security, food security, power generation, and economic development. However, the available data are frequently far from sufficient – in terms of availability, accuracy, and spa-tial/temporal resolution – for the understanding of both natural and anthropogenic processes (and their complex linkages) in a river basin. Such challenges also make it very difficult to use the data for the practical application of estimation of water resources availability.
- Full Text:
- Date Issued: 2021
- Authors: Kapangaziwiri, Evison , Kahinda, Jean-Marc M , Oosthuizen, Nadia , Mvandaba, Vuyelwa , Hobbs, Philip , Hughes, Denis A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438349 , vital:73453 , ISBN 978-0-6392-0303-4 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2439_final.pdf
- Description: The complexity of current water resource management poses many challenges. Wa-ter managers must solve a range of interrelated dilemmas – such as balancing quan-tity and quality, mitigating the effects of flooding and drought, and maintaining bio-diversity, ecological functions, and services. Sustainable water resource manage-ment, planning, and development requires reliable quantification of the amount, distribution, and quality of water within river basins. With the demand for water resources rapidly growing across the globe, there is also an urgent need for accu-rate monitoring, forecasting and simulation of hydrologic variables – especially in major (often transboundary) river basins such as the Limpopo – not only for optimal water resources management but more compellingly, also for water security, food security, power generation, and economic development. However, the available data are frequently far from sufficient – in terms of availability, accuracy, and spa-tial/temporal resolution – for the understanding of both natural and anthropogenic processes (and their complex linkages) in a river basin. Such challenges also make it very difficult to use the data for the practical application of estimation of water resources availability.
- Full Text:
- Date Issued: 2021
Turn-on detection of cysteine by a donor-acceptor type quinoline fluorophore: Exploring the sensing strategy and performance in bioimaging
- Muthusamy, Selvaraj, Zhao, Long, Rajalakshmi, Kanagaraj, Zhu, Dongwei, Soy, Rodah, Mack, John, Nyokong, Tebello, Wang, Shengjun, Lee, Kang-Bong, Zhu, Weihua
- Authors: Muthusamy, Selvaraj , Zhao, Long , Rajalakshmi, Kanagaraj , Zhu, Dongwei , Soy, Rodah , Mack, John , Nyokong, Tebello , Wang, Shengjun , Lee, Kang-Bong , Zhu, Weihua
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185644 , vital:44406 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109556"
- Description: Tracking the biothiol cysteine (Cys) in living systems is a significant responsibility to balance the redox environment and oxidative stress. A quinoline-7-nitro-1,2,3-benzoxadiazole (Q-NBD) fluorophore has been synthesized and characterized towards examination of Cys. The probe forms a quinoline-substituted phenol (Q-Ph-OH) after thiolysis of the NBD ether bond, leading to an increase of fluorescence at green channel. The turn-on sensing mechanism originates from the change in intramolecular charge transfer (ICT-OFF) along with an aggregation-induced emission (AIE) as suggested by spectroscopy measurements in solutions, time-dependent density-functional theory (TD-DFT) calculations and 1H NMR titration examination. Importantly, Q-NBD exhibited great sensitivity with a low limit of detection value of 89.5 nM and remarkable selectivity in various biothiols towards Cys. The sensor probe was successfully used for detecting both endogenous and exogenous Cys in PC3 living cells and spiked Cys in human urine samples.
- Full Text:
- Date Issued: 2021
- Authors: Muthusamy, Selvaraj , Zhao, Long , Rajalakshmi, Kanagaraj , Zhu, Dongwei , Soy, Rodah , Mack, John , Nyokong, Tebello , Wang, Shengjun , Lee, Kang-Bong , Zhu, Weihua
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185644 , vital:44406 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109556"
- Description: Tracking the biothiol cysteine (Cys) in living systems is a significant responsibility to balance the redox environment and oxidative stress. A quinoline-7-nitro-1,2,3-benzoxadiazole (Q-NBD) fluorophore has been synthesized and characterized towards examination of Cys. The probe forms a quinoline-substituted phenol (Q-Ph-OH) after thiolysis of the NBD ether bond, leading to an increase of fluorescence at green channel. The turn-on sensing mechanism originates from the change in intramolecular charge transfer (ICT-OFF) along with an aggregation-induced emission (AIE) as suggested by spectroscopy measurements in solutions, time-dependent density-functional theory (TD-DFT) calculations and 1H NMR titration examination. Importantly, Q-NBD exhibited great sensitivity with a low limit of detection value of 89.5 nM and remarkable selectivity in various biothiols towards Cys. The sensor probe was successfully used for detecting both endogenous and exogenous Cys in PC3 living cells and spiked Cys in human urine samples.
- Full Text:
- Date Issued: 2021
Ultrasound-Triggered Release of 5-Fluorouracil from Soy Lecithin Echogenic Liposomes
- Ezekiel, Charles I, Bapolisi, Alain M, Walker, Roderick B, Krause, Rui W M
- Authors: Ezekiel, Charles I , Bapolisi, Alain M , Walker, Roderick B , Krause, Rui W M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183115 , vital:43913 , xlink:href="https://doi.org/10.3390/pharmaceutics13060821"
- Description: Colorectal cancer is the third most diagnosed cancer and the second leading cause of death. The use of 5-fluorouracil (5-FU) has been the major chemotherapeutic treatment for colorectal cancer patients. However, the efficacy of 5-FU is limited by drug resistance, and bone marrow toxicity through high-level expression of thymidylate synthase, justifying the need for improvement of the therapeutic index. In this study, the effects of ultrasound on echogenic 5-FU encapsulated crude soy liposomes were investigated for their potential to address these challenges. Liposomes were prepared by thin-film hydration using crude soy lecithin and cholesterol. Argon gas was entrapped in the liposomes for sonosensitivity (that is, responsiveness to ultrasound). The nanoparticles were characterized for particle size and morphology. The physicochemical properties were also evaluated using differential scanning calorimetry, Fourier transform infrared and X-ray diffraction. The release profile of 5-FU was assessed with and without 20 kHz low-frequency ultrasound waves at various amplitudes and exposure times. The result reveal that 5-FU-loaded liposomes were spherical with an encapsulation efficiency of approximately 60%. Approximately 65% of 5-FU was released at the highest amplitude and exposure time was investigated. The results are encouraging for the stimulated and controlled release of 5-FU for the management of colorectal cancer.
- Full Text:
- Date Issued: 2021
- Authors: Ezekiel, Charles I , Bapolisi, Alain M , Walker, Roderick B , Krause, Rui W M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183115 , vital:43913 , xlink:href="https://doi.org/10.3390/pharmaceutics13060821"
- Description: Colorectal cancer is the third most diagnosed cancer and the second leading cause of death. The use of 5-fluorouracil (5-FU) has been the major chemotherapeutic treatment for colorectal cancer patients. However, the efficacy of 5-FU is limited by drug resistance, and bone marrow toxicity through high-level expression of thymidylate synthase, justifying the need for improvement of the therapeutic index. In this study, the effects of ultrasound on echogenic 5-FU encapsulated crude soy liposomes were investigated for their potential to address these challenges. Liposomes were prepared by thin-film hydration using crude soy lecithin and cholesterol. Argon gas was entrapped in the liposomes for sonosensitivity (that is, responsiveness to ultrasound). The nanoparticles were characterized for particle size and morphology. The physicochemical properties were also evaluated using differential scanning calorimetry, Fourier transform infrared and X-ray diffraction. The release profile of 5-FU was assessed with and without 20 kHz low-frequency ultrasound waves at various amplitudes and exposure times. The result reveal that 5-FU-loaded liposomes were spherical with an encapsulation efficiency of approximately 60%. Approximately 65% of 5-FU was released at the highest amplitude and exposure time was investigated. The results are encouraging for the stimulated and controlled release of 5-FU for the management of colorectal cancer.
- Full Text:
- Date Issued: 2021
Understanding the food crises in southern Africa and the ways of transitioning the food systems to combat hunger
- Chakona, Gamuchirai, Mushangai, Dandira
- Authors: Chakona, Gamuchirai , Mushangai, Dandira
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , working paper
- Identifier: http://hdl.handle.net/10962/433956 , vital:73014 , ISBN working paper
- Description: Globally, almost one billion people are estimated to face hunger on a regular basis (Poppy et al., 2014) and more than two billion people suffer from micronutrient deficiencies (Barrett, 2010; FAO et al. 2020). The number of food-insecure people has been on the rise with subSaharan Africa having the greatest number of individuals who are both hungry (about 237 million people) and malnourished (almost 23% of the population) (FAO, 2018). Beyond hunger, FAO et al. (2020) noted that a growing number of people have had to reduce the quantity and quality of the food they consume. This makes it almost impossible to have a world with zero hunger by 2030 and achieve SDG 2 target 2.1 of ensuring access to safe, nutritious and sufficient food for all people and target 2.2 of eradicating all forms of malnutrition (UN 2015). Most governments globally have pledged to eradicate hunger in their nations by 2030, and one of their solutions is to increase agricultural productivity to meet the needs of all their people. However, Poppy et al. (2014) argued that increased yields and food supplies do not assure food security for all as some poorer societies and communities may not have access to sufficient quantity or quality food (Iram and Butt, 2004), which is a challenge in many African communities, especially in South Africa. This highlights the complexity of the food system within many countries.
- Full Text:
- Date Issued: 2021
- Authors: Chakona, Gamuchirai , Mushangai, Dandira
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , working paper
- Identifier: http://hdl.handle.net/10962/433956 , vital:73014 , ISBN working paper
- Description: Globally, almost one billion people are estimated to face hunger on a regular basis (Poppy et al., 2014) and more than two billion people suffer from micronutrient deficiencies (Barrett, 2010; FAO et al. 2020). The number of food-insecure people has been on the rise with subSaharan Africa having the greatest number of individuals who are both hungry (about 237 million people) and malnourished (almost 23% of the population) (FAO, 2018). Beyond hunger, FAO et al. (2020) noted that a growing number of people have had to reduce the quantity and quality of the food they consume. This makes it almost impossible to have a world with zero hunger by 2030 and achieve SDG 2 target 2.1 of ensuring access to safe, nutritious and sufficient food for all people and target 2.2 of eradicating all forms of malnutrition (UN 2015). Most governments globally have pledged to eradicate hunger in their nations by 2030, and one of their solutions is to increase agricultural productivity to meet the needs of all their people. However, Poppy et al. (2014) argued that increased yields and food supplies do not assure food security for all as some poorer societies and communities may not have access to sufficient quantity or quality food (Iram and Butt, 2004), which is a challenge in many African communities, especially in South Africa. This highlights the complexity of the food system within many countries.
- Full Text:
- Date Issued: 2021
Unlocking the Diversity of Pyrroloiminoquinones Produced by Latrunculid Sponge Species
- Kalinski, Jarmo-Charles J, Krause, Rui W M, Parker-Nance, Shirley, Waterworth, Samantha C, Dorrington, Rosemary A
- Authors: Kalinski, Jarmo-Charles J , Krause, Rui W M , Parker-Nance, Shirley , Waterworth, Samantha C , Dorrington, Rosemary A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191802 , vital:45165 , xlink:href="https://doi.org/10.3390/md19020068"
- Description: Sponges of the Latrunculiidae family produce bioactive pyrroloiminoquinone alkaloids including makaluvamines, discorhabdins, and tsitsikammamines. The aim of this study was to use LC-ESI-MS/MS-driven molecular networking to characterize the pyrroloiminoquinone secondary metabolites produced by six latrunculid species. These are Tsitsikamma favus, Tsitsikamma pedunculata, Cyclacanthia bellae, and Latrunculia apicalis as well as the recently discovered species, Tsitsikamma nguni and Tsitsikamma michaeli. Organic extracts of 43 sponges were analyzed, revealing distinct species-specific chemical profiles. More than 200 known and unknown putative pyrroloiminoquinones and related compounds were detected, including unprecedented makaluvamine-discorhabdin adducts and hydroxylated discorhabdin I derivatives. The chemical profiles of the new species T. nguni closely resembled those of the known T. favus (chemotype I), but with a higher abundance of tsitsikammamines vs. discorhabdins. T. michaeli sponges displayed two distinct chemical profiles, either producing mostly the same discorhabdins as T. favus (chemotype I) or non- or monobrominated, hydroxylated discorhabdins. C. bellae and L. apicalis produced similar pyrroloiminoquinone chemistry to one another, characterized by sulfur-containing discorhabdins and related adducts and oligomers. This study highlights the variability of pyrroloiminoquinone production by latrunculid species, identifies novel isolation targets, and offers fundamental insights into the collision-induced dissociation of pyrroloiminoquinones.
- Full Text:
- Date Issued: 2021
- Authors: Kalinski, Jarmo-Charles J , Krause, Rui W M , Parker-Nance, Shirley , Waterworth, Samantha C , Dorrington, Rosemary A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191802 , vital:45165 , xlink:href="https://doi.org/10.3390/md19020068"
- Description: Sponges of the Latrunculiidae family produce bioactive pyrroloiminoquinone alkaloids including makaluvamines, discorhabdins, and tsitsikammamines. The aim of this study was to use LC-ESI-MS/MS-driven molecular networking to characterize the pyrroloiminoquinone secondary metabolites produced by six latrunculid species. These are Tsitsikamma favus, Tsitsikamma pedunculata, Cyclacanthia bellae, and Latrunculia apicalis as well as the recently discovered species, Tsitsikamma nguni and Tsitsikamma michaeli. Organic extracts of 43 sponges were analyzed, revealing distinct species-specific chemical profiles. More than 200 known and unknown putative pyrroloiminoquinones and related compounds were detected, including unprecedented makaluvamine-discorhabdin adducts and hydroxylated discorhabdin I derivatives. The chemical profiles of the new species T. nguni closely resembled those of the known T. favus (chemotype I), but with a higher abundance of tsitsikammamines vs. discorhabdins. T. michaeli sponges displayed two distinct chemical profiles, either producing mostly the same discorhabdins as T. favus (chemotype I) or non- or monobrominated, hydroxylated discorhabdins. C. bellae and L. apicalis produced similar pyrroloiminoquinone chemistry to one another, characterized by sulfur-containing discorhabdins and related adducts and oligomers. This study highlights the variability of pyrroloiminoquinone production by latrunculid species, identifies novel isolation targets, and offers fundamental insights into the collision-induced dissociation of pyrroloiminoquinones.
- Full Text:
- Date Issued: 2021
Urban ecology of the Global South
- du Toit, Marie J, Shackleton, Charlie M, Cilliers, Sarel S, Davoren, Elandre
- Authors: du Toit, Marie J , Shackleton, Charlie M , Cilliers, Sarel S , Davoren, Elandre
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/433728 , vital:72997 , ISBN 978-3-030-67650-6 , https://doi.org/10.1007/978-3-030-67650-6
- Description: Against the background of unprecedented rates of urbanisation in the Global South, leading to massive social, economic and environmental transformations, this book engages with the dire need to understand the ecology of such settings as the foundation for fostering sustainable and resilient human settlements in contexts that are very different to the Global North. It does so by bringing together scholars from around the world, drawing together research and case studies from across the Global South to illustrate, in an interdisciplinary and comprehensive fashion, the ecology of towns and cities in the Global South. Framed using a social-ecological systems lens, it provides the reader with an in-depth analysis and understanding of the ecological dynamics and ecosystem services and disservices within the complex and rapidly changing towns and cities of the Global South, a region with currently scarce representation in most of the urban ecology literature. As such the book makes a call for greater geographical balance in urban ecology research leading towards a more global understanding and frameworks. The book embraces the complexity of these rapid transformations for ecological and environmental management and how the ecosystems and the benefits they provide shape local ecologies, livelihood opportunities and human wellbeing, and how such knowledge can be mobilised towards improved urban design and management and thus urban sustainability.
- Full Text:
- Date Issued: 2021
- Authors: du Toit, Marie J , Shackleton, Charlie M , Cilliers, Sarel S , Davoren, Elandre
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/433728 , vital:72997 , ISBN 978-3-030-67650-6 , https://doi.org/10.1007/978-3-030-67650-6
- Description: Against the background of unprecedented rates of urbanisation in the Global South, leading to massive social, economic and environmental transformations, this book engages with the dire need to understand the ecology of such settings as the foundation for fostering sustainable and resilient human settlements in contexts that are very different to the Global North. It does so by bringing together scholars from around the world, drawing together research and case studies from across the Global South to illustrate, in an interdisciplinary and comprehensive fashion, the ecology of towns and cities in the Global South. Framed using a social-ecological systems lens, it provides the reader with an in-depth analysis and understanding of the ecological dynamics and ecosystem services and disservices within the complex and rapidly changing towns and cities of the Global South, a region with currently scarce representation in most of the urban ecology literature. As such the book makes a call for greater geographical balance in urban ecology research leading towards a more global understanding and frameworks. The book embraces the complexity of these rapid transformations for ecological and environmental management and how the ecosystems and the benefits they provide shape local ecologies, livelihood opportunities and human wellbeing, and how such knowledge can be mobilised towards improved urban design and management and thus urban sustainability.
- Full Text:
- Date Issued: 2021
Urban ecosystem disservices in the Global South
- Davoren, Elandre, Shackleton, Charlie M
- Authors: Davoren, Elandre , Shackleton, Charlie M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433780 , vital:73000 , ISBN 978-3-030-67650-6 , https://doi.org/10.1007/978-3-030-67650-6_11
- Description: As much as people benefit from the ecosystem services provided by nature, ecosystem disservices also impact daily lives. This is especially true for many urban communities in the Global South due to (1) the often greater diversity of ecosystem disservices and (2) higher vulnerabilities, which together can lead to greater impacts of ecosystem disservices in many Global South settings. This chapter provides an overview of the current understandings of urban ecosystem disservices and their assessment and management with an emphasis on the Global South, albeit with reference to the Global North where useful. This overview reveals a lack of detailed and systematic empirical research on urban ecosystem disservices generally, but even more so in the Global South, despite the greater diversity and vulnerability in Global South settings. This needs to be acknowledged in urban ecology framings of urban dynamics in the Global South and translated into better integration of both ecosystem services and disservices within common research, policy or management frameworks. It is only through such integration that appropriate context-relevant policy directions and management options can be identified, thereby promoting the wellbeing of urban citizens in the Global South.
- Full Text:
- Date Issued: 2021
- Authors: Davoren, Elandre , Shackleton, Charlie M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433780 , vital:73000 , ISBN 978-3-030-67650-6 , https://doi.org/10.1007/978-3-030-67650-6_11
- Description: As much as people benefit from the ecosystem services provided by nature, ecosystem disservices also impact daily lives. This is especially true for many urban communities in the Global South due to (1) the often greater diversity of ecosystem disservices and (2) higher vulnerabilities, which together can lead to greater impacts of ecosystem disservices in many Global South settings. This chapter provides an overview of the current understandings of urban ecosystem disservices and their assessment and management with an emphasis on the Global South, albeit with reference to the Global North where useful. This overview reveals a lack of detailed and systematic empirical research on urban ecosystem disservices generally, but even more so in the Global South, despite the greater diversity and vulnerability in Global South settings. This needs to be acknowledged in urban ecology framings of urban dynamics in the Global South and translated into better integration of both ecosystem services and disservices within common research, policy or management frameworks. It is only through such integration that appropriate context-relevant policy directions and management options can be identified, thereby promoting the wellbeing of urban citizens in the Global South.
- Full Text:
- Date Issued: 2021
Urban green infrastructure for poverty alleviation: evidence synthesis and conceptual considerations
- Authors: Shackleton, Charlie M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/401383 , vital:69730 , xlink:href="https://doi.org/10.3389/frsc.2021.710549"
- Description: The multiple benefits of urban green infrastructure (UGI) that support sustainable cities are increasingly acknowledged, and yet the bulk of research over the past decade or so has focused on only a small subset of the numerous benefits, notably recreation, physical and mental health, and regulating services. In contrast, there is very little information on the contribution of UGI to several of the other Sustainable Development Goals (SDGs), and in particular SDG 1 of reducing poverty, despite the pervasiveness of poverty globally. This paper considers the diverse direct and indirect ways in which UGI can contribute to poverty alleviation, drawing on the limited evidence from various regions of the world. The direct links between UGI and poverty alleviation is via three means, namely provision of (1) consumptive or provisioning goods such as wild foods and firewood, (2) employment in UGI development, maintenance, and restoration, and (3) land for urban agriculture, income generation and dwelling. There are also a number of indirect links such as cash savings, improved physical and mental health, improved social networks, improved educational outcomes, and regulation of potential natural disasters. However, the commonly unequal distribution of UGI within and between cities means that the poverty alleviation potential and benefits are inequitably distributed, often against those who are most in need of them, i.e., the urban poor. This demands greater attention to promoting the equitable distribution and quality of UGI and mainstreaming of UGI into poverty reduction strategies and programmes and vice versa, as well as greater examination of the links between UGI and poverty alleviation in a greater range of contexts.
- Full Text:
- Date Issued: 2021
Urban green infrastructure for poverty alleviation: evidence synthesis and conceptual considerations
- Authors: Shackleton, Charlie M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/401383 , vital:69730 , xlink:href="https://doi.org/10.3389/frsc.2021.710549"
- Description: The multiple benefits of urban green infrastructure (UGI) that support sustainable cities are increasingly acknowledged, and yet the bulk of research over the past decade or so has focused on only a small subset of the numerous benefits, notably recreation, physical and mental health, and regulating services. In contrast, there is very little information on the contribution of UGI to several of the other Sustainable Development Goals (SDGs), and in particular SDG 1 of reducing poverty, despite the pervasiveness of poverty globally. This paper considers the diverse direct and indirect ways in which UGI can contribute to poverty alleviation, drawing on the limited evidence from various regions of the world. The direct links between UGI and poverty alleviation is via three means, namely provision of (1) consumptive or provisioning goods such as wild foods and firewood, (2) employment in UGI development, maintenance, and restoration, and (3) land for urban agriculture, income generation and dwelling. There are also a number of indirect links such as cash savings, improved physical and mental health, improved social networks, improved educational outcomes, and regulation of potential natural disasters. However, the commonly unequal distribution of UGI within and between cities means that the poverty alleviation potential and benefits are inequitably distributed, often against those who are most in need of them, i.e., the urban poor. This demands greater attention to promoting the equitable distribution and quality of UGI and mainstreaming of UGI into poverty reduction strategies and programmes and vice versa, as well as greater examination of the links between UGI and poverty alleviation in a greater range of contexts.
- Full Text:
- Date Issued: 2021
Visible light responsive TiO2-graphene oxide nanosheets-Zn phthalocyanine ternary heterojunction assisted photoelectrocatalytic degradation of Orange G
- Nwahara, Nnamdi, Adeniyi, Omotayo, Mashazi, Philani N, Nyokong, Tebello
- Authors: Nwahara, Nnamdi , Adeniyi, Omotayo , Mashazi, Philani N , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185446 , vital:44387 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113291"
- Description: Herein, we report on the successful fabrication of a visible light-responsive TiO2 - graphene oxide nanosheets – Zn phthalocyanine (TiO2@GONS@ZnPc) ternary structure for the photoelectrochemical degradation of Orange G azo dye. The characterization of TiO2@GONS@ZnPc composite was achieved using various spectroscopic and microscopic techniques. Our results show that the TiO2@GONS@ZnPc surface hybrid heterojunction promotes charge separation and electron migration, significantly improving the degradation efficiency with an applied potential. For the first time, we show the existence of a non-radical activation route for persulfate (PS) using such π electron-rich ZnPc-GONS catalysts. The degradation kinetics were found to follow pseudo first order kinetics. Electron spin resonance analyses suggested that neither hydroxyl radicals nor sulfate radicals were produced therein, and therefore were not responsible for the persulfate-driven oxidation of the OG dye. These findings suggest that both which GONS and ZnPc play a critical role in mediating the eventual charge transfer mediated PS activation. The results illustrate the remarkable capacity of the TiO2@GONS@ZnPc composite to rapidly degrade Orange G by a coupled TiO2@GONS@ZnPc-persulfate system.
- Full Text:
- Date Issued: 2021
- Authors: Nwahara, Nnamdi , Adeniyi, Omotayo , Mashazi, Philani N , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185446 , vital:44387 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113291"
- Description: Herein, we report on the successful fabrication of a visible light-responsive TiO2 - graphene oxide nanosheets – Zn phthalocyanine (TiO2@GONS@ZnPc) ternary structure for the photoelectrochemical degradation of Orange G azo dye. The characterization of TiO2@GONS@ZnPc composite was achieved using various spectroscopic and microscopic techniques. Our results show that the TiO2@GONS@ZnPc surface hybrid heterojunction promotes charge separation and electron migration, significantly improving the degradation efficiency with an applied potential. For the first time, we show the existence of a non-radical activation route for persulfate (PS) using such π electron-rich ZnPc-GONS catalysts. The degradation kinetics were found to follow pseudo first order kinetics. Electron spin resonance analyses suggested that neither hydroxyl radicals nor sulfate radicals were produced therein, and therefore were not responsible for the persulfate-driven oxidation of the OG dye. These findings suggest that both which GONS and ZnPc play a critical role in mediating the eventual charge transfer mediated PS activation. The results illustrate the remarkable capacity of the TiO2@GONS@ZnPc composite to rapidly degrade Orange G by a coupled TiO2@GONS@ZnPc-persulfate system.
- Full Text:
- Date Issued: 2021
What are social-ecological systems and social-ecological systems research
- Biggs, Reinette, Clements, Hayley, de Vos, Alta, Folke, Carl, Manyani, Amanda, Maciejewski, Kristine, Martin-Lopez, Berta, Preiser, Rika, Selomane, Odirilwe, Schluter, Maja
- Authors: Biggs, Reinette , Clements, Hayley , de Vos, Alta , Folke, Carl , Manyani, Amanda , Maciejewski, Kristine , Martin-Lopez, Berta , Preiser, Rika , Selomane, Odirilwe , Schluter, Maja
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433900 , vital:73008 , ISBN 9781000401516 , https://library.oapen.org/handle/20.500.12657/49560
- Description: The period since the Second World War has been marked by rapid and accelerating changes to many aspects of human society and the environment (Clark, Crutzen, and Schellnhuber 2004; Steffen et al. 2011; Steffen et al. 2015a). There is accumulating evidence and rising concern about the potential consequences these changes hold for key Earth system processes at a global scale, and human well-being and prosperity into the future (Krausmann et al. 2013; Steffen et al. 2015b). The Anthropocene, as this new era of extensive human impact on the Earth has come to be known (Crutzen 2006), manifests in a closely intertwined set of social and ecological changes. Technological advances, increasing human population, rising levels of wealth and consumption, and the institutional arrangements we have developed to govern our economies and societies interplay with one another, and drastically affect the Earth’s climate, biological diversity, fresh-water and biogeochemical flows, and levels of novel pollutants in the environment (Steffen et al. 2015a). These environmental changes, in turn, contribute to increasingly frequent and severe droughts (Dai 2013; Trenberth et al. 2014), floods (Milly et al. 2002; Nicholls 2004), heatwaves (Guo et al. 2018; Oliver et al. 2018) and the emergence of novel pathogens such as SARS-CoV-2 (Everard et al. 2020; O ’Callaghan-Gordo and Antò 2020; Schmeller, Courchamp, and Killeen 2020) that can lead to massive societal disruption and hardship, especially among the poor (Wheeler and Von Braun 2013; Barbier and Hochard 2018).
- Full Text:
- Date Issued: 2021
- Authors: Biggs, Reinette , Clements, Hayley , de Vos, Alta , Folke, Carl , Manyani, Amanda , Maciejewski, Kristine , Martin-Lopez, Berta , Preiser, Rika , Selomane, Odirilwe , Schluter, Maja
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433900 , vital:73008 , ISBN 9781000401516 , https://library.oapen.org/handle/20.500.12657/49560
- Description: The period since the Second World War has been marked by rapid and accelerating changes to many aspects of human society and the environment (Clark, Crutzen, and Schellnhuber 2004; Steffen et al. 2011; Steffen et al. 2015a). There is accumulating evidence and rising concern about the potential consequences these changes hold for key Earth system processes at a global scale, and human well-being and prosperity into the future (Krausmann et al. 2013; Steffen et al. 2015b). The Anthropocene, as this new era of extensive human impact on the Earth has come to be known (Crutzen 2006), manifests in a closely intertwined set of social and ecological changes. Technological advances, increasing human population, rising levels of wealth and consumption, and the institutional arrangements we have developed to govern our economies and societies interplay with one another, and drastically affect the Earth’s climate, biological diversity, fresh-water and biogeochemical flows, and levels of novel pollutants in the environment (Steffen et al. 2015a). These environmental changes, in turn, contribute to increasingly frequent and severe droughts (Dai 2013; Trenberth et al. 2014), floods (Milly et al. 2002; Nicholls 2004), heatwaves (Guo et al. 2018; Oliver et al. 2018) and the emergence of novel pathogens such as SARS-CoV-2 (Everard et al. 2020; O ’Callaghan-Gordo and Antò 2020; Schmeller, Courchamp, and Killeen 2020) that can lead to massive societal disruption and hardship, especially among the poor (Wheeler and Von Braun 2013; Barbier and Hochard 2018).
- Full Text:
- Date Issued: 2021
Youth Attitudes and Participation in Climate Protest
- Prendergast, Kate, Hayward, Bronwyn, Aoyagi, Midori, Burningham, Kate, Hasan, Mehedi, Jackson, Tim, Jha, Vimlendu, Kuroki, Larissa, Lukianov, Anastasia, Mattar, Helio, Schudel, Ingrid J, Venn, Sue, Yoshida, Aya
- Authors: Prendergast, Kate , Hayward, Bronwyn , Aoyagi, Midori , Burningham, Kate , Hasan, Mehedi , Jackson, Tim , Jha, Vimlendu , Kuroki, Larissa , Lukianov, Anastasia , Mattar, Helio , Schudel, Ingrid J , Venn, Sue , Yoshida, Aya
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/294471 , vital:57224 , xlink:href="https://doi.org/10.3389/fpos.2021.696105"
- Description: This article examines youth participation the school climate strikes of 2018 and 2019 (also known as #Fridays4Future), through an exploratory study conducted in seven diverse cities. Despite the international nature of the climate strikes, we know little about the factors that influenced youth participation in these protests beyond the global North. This matters because youth of the global South are disproportionately impacted by climate change and there is growing concern that the climate movement is dominated by narratives that marginalize the voices and priorities of Indigenous communities and people of color. In this context, the exploratory research reported here aimed to compare the attitudes of climate protesters (n = 314) and their non-protester peers (n = 1,217), in diverse city samples drawn from a wider study of children and youth aged 12–24 years, living in Christchurch (New Zealand); Dhaka (Bangladesh); Lambeth, London (United Kingdom); Makhanda (South Africa); New Delhi (India); São Paulo (Brazil); and Yokohama (Japan). Using cross-sectional data (N = 1,531) and binary logistic regression models, researchers examined three common explanations for youth participation in protest: availability (biographical and structural), political engagement (reported individual and collective efficacy of strikers and non-strikers), and self-reported biospheric values amongst participants. Results indicate that even in diverse city samples, structural availability (civic skills and organizational membership) predicted strike participation across city samples, but not political engagement (self-efficacy and collective efficacy). Youth who reported that ‘living in harmony with nature and animals’ was important for their wellbeing, were also more likely to strike than their peers. Descriptive statistics indicated that the majority (85 percent) of all protestors in this study agreed climate change was a serious issue and a startling 65 percent said that they think about climate change “all the time”. Reported rates of youth climate protest participation varied across city samples as did the extent to which participants reported having friends take part or expecting climate change to have a personal impact. While the study is exploratory, it points to the need for more extensive research to understand the diversity of youth participation in ‘global climate strikes’.
- Full Text:
- Date Issued: 2021
- Authors: Prendergast, Kate , Hayward, Bronwyn , Aoyagi, Midori , Burningham, Kate , Hasan, Mehedi , Jackson, Tim , Jha, Vimlendu , Kuroki, Larissa , Lukianov, Anastasia , Mattar, Helio , Schudel, Ingrid J , Venn, Sue , Yoshida, Aya
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/294471 , vital:57224 , xlink:href="https://doi.org/10.3389/fpos.2021.696105"
- Description: This article examines youth participation the school climate strikes of 2018 and 2019 (also known as #Fridays4Future), through an exploratory study conducted in seven diverse cities. Despite the international nature of the climate strikes, we know little about the factors that influenced youth participation in these protests beyond the global North. This matters because youth of the global South are disproportionately impacted by climate change and there is growing concern that the climate movement is dominated by narratives that marginalize the voices and priorities of Indigenous communities and people of color. In this context, the exploratory research reported here aimed to compare the attitudes of climate protesters (n = 314) and their non-protester peers (n = 1,217), in diverse city samples drawn from a wider study of children and youth aged 12–24 years, living in Christchurch (New Zealand); Dhaka (Bangladesh); Lambeth, London (United Kingdom); Makhanda (South Africa); New Delhi (India); São Paulo (Brazil); and Yokohama (Japan). Using cross-sectional data (N = 1,531) and binary logistic regression models, researchers examined three common explanations for youth participation in protest: availability (biographical and structural), political engagement (reported individual and collective efficacy of strikers and non-strikers), and self-reported biospheric values amongst participants. Results indicate that even in diverse city samples, structural availability (civic skills and organizational membership) predicted strike participation across city samples, but not political engagement (self-efficacy and collective efficacy). Youth who reported that ‘living in harmony with nature and animals’ was important for their wellbeing, were also more likely to strike than their peers. Descriptive statistics indicated that the majority (85 percent) of all protestors in this study agreed climate change was a serious issue and a startling 65 percent said that they think about climate change “all the time”. Reported rates of youth climate protest participation varied across city samples as did the extent to which participants reported having friends take part or expecting climate change to have a personal impact. While the study is exploratory, it points to the need for more extensive research to understand the diversity of youth participation in ‘global climate strikes’.
- Full Text:
- Date Issued: 2021
‘Don't educate them out of educating themselves’
- Krueger, Anton, Wunder, Albert
- Authors: Krueger, Anton , Wunder, Albert
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225481 , vital:49226 , xlink:href="https://doi.org/10.5920/pam.1005"
- Description: Al Wunder's biography, in his own words: I had four lucky breaks that precipitated my becoming a teacher of improvised movement theatre. Between the ages of eight and fourteen I broke my right leg four different times. In 1962, I began modern dance classes with Alwin Nikolais as a physical therapy. His choreography and improvisation sections of class inspired me to teach and perform professionally. I spent eight years studying, teaching, choreographing, and performing with Nikolais. 1970 saw me move to the San Francisco Bay area where I opened a dance studio teaching Nikolais dance technique and improvisation. In 1971, I joined forces with Terry Sendgraff and Ruth Zaporah creating The Berkeley Dance Theater and Gymnasium. My focus was to create a way to teach dance technique through improvisation. I met my Australian wife, Lynden Nicholls, in 1981 when she came to study Motivity at Terry’s studio in Berkeley. In 1982, I moved to Melbourne, Australia where Lynden and I set up a dance studio. My focus changed from teaching dance technique improvisationally to teaching improvised movement theatre performance
- Full Text:
- Date Issued: 2021
- Authors: Krueger, Anton , Wunder, Albert
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225481 , vital:49226 , xlink:href="https://doi.org/10.5920/pam.1005"
- Description: Al Wunder's biography, in his own words: I had four lucky breaks that precipitated my becoming a teacher of improvised movement theatre. Between the ages of eight and fourteen I broke my right leg four different times. In 1962, I began modern dance classes with Alwin Nikolais as a physical therapy. His choreography and improvisation sections of class inspired me to teach and perform professionally. I spent eight years studying, teaching, choreographing, and performing with Nikolais. 1970 saw me move to the San Francisco Bay area where I opened a dance studio teaching Nikolais dance technique and improvisation. In 1971, I joined forces with Terry Sendgraff and Ruth Zaporah creating The Berkeley Dance Theater and Gymnasium. My focus was to create a way to teach dance technique through improvisation. I met my Australian wife, Lynden Nicholls, in 1981 when she came to study Motivity at Terry’s studio in Berkeley. In 1982, I moved to Melbourne, Australia where Lynden and I set up a dance studio. My focus changed from teaching dance technique improvisationally to teaching improvised movement theatre performance
- Full Text:
- Date Issued: 2021
The modulation of the photophysical and photodynamic therapy activities of a phthalocyanine by detonation nanodiamonds: Comparison with graphene quantum dots and carbon nanodots
- Matshitse, Refilwe, Managa, Muthumuni, Nyokong, Tebello
- Authors: Matshitse, Refilwe , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186690 , vital:44525 , xlink:href="https://doi.org/10.1016/j.diamond.2019.107617"
- Description: A positively charged phthalocyanine (2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]-phthalocyanine (ZnTPPcQ)) was non-covalently linked to carbon based nanoparticles: detonation nanodiamonds (DNDs), carbon dots (CDs) and graphene quantum dots (GQDs) to form nanosembles of DNDs-ZnTPPcQ, GQDs-ZnTPPcQ and CDs-ZnTPPcQ, respectively. Irrespective of its small size and the least number of Pcs (41.67 μg loading per milligram of DNDs), DNDs-ZnTPPcQ gave the highest singlet oxygen quantum yield (0.62) in dimethyl sulfoxide compared to the rest of the conjugates. This resulted in superior PDT activity against MCF7 breast cancer lines, with the lowest cell viability of 28% compared to ZnTPPcQ-CDs and ZnTPPcQ-GQDs at 30.1 ± 0.02% and 31.4 ± 0.23%, respectively.
- Full Text:
- Date Issued: 2020
- Authors: Matshitse, Refilwe , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186690 , vital:44525 , xlink:href="https://doi.org/10.1016/j.diamond.2019.107617"
- Description: A positively charged phthalocyanine (2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]-phthalocyanine (ZnTPPcQ)) was non-covalently linked to carbon based nanoparticles: detonation nanodiamonds (DNDs), carbon dots (CDs) and graphene quantum dots (GQDs) to form nanosembles of DNDs-ZnTPPcQ, GQDs-ZnTPPcQ and CDs-ZnTPPcQ, respectively. Irrespective of its small size and the least number of Pcs (41.67 μg loading per milligram of DNDs), DNDs-ZnTPPcQ gave the highest singlet oxygen quantum yield (0.62) in dimethyl sulfoxide compared to the rest of the conjugates. This resulted in superior PDT activity against MCF7 breast cancer lines, with the lowest cell viability of 28% compared to ZnTPPcQ-CDs and ZnTPPcQ-GQDs at 30.1 ± 0.02% and 31.4 ± 0.23%, respectively.
- Full Text:
- Date Issued: 2020
Electrocatalytic activity of a push pull Co (II) phthalocyanine in the presence of graphitic carbon nitride quantum dots
- Nxele, Siphesihle R, Oluwole, David O, Nyokong, Tebello
- Authors: Nxele, Siphesihle R , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186746 , vital:44530 , xlink:href="https://doi.org/10.1016/j.electacta.2019.134978"
- Description: This work reports for the first time on the use of a conjugate of graphitic carbon nitride quantum dots (gCNQDs) with a push-pull asymmetrical cobalt phthalocyanine (CoPc) for electrochemical sensing. The nanocomposite is immobilized on a glassy carbon electrode (GCE) surface for the use in l-cysteine electrocatalysis. The nanocomposites were characterized using techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Raman spectroscopy and electrochemical methods. The nanocomposites were immobilized by the drop-dry method, sequentially or when premixed in solution. Good electrocatalytic oxidation of l-cysteine was observed, especially by the sequentially modified electrode surface, with the CoPc on top of gCNQDs. The sensitivity was determined as 3.5 μA.mM-1 and the limit of detection (LoD) as 101.3 μM for GCE-gCNQDs, 0.65 μA.mM-1 and 0.96 μM for GCE-CoPc, 23.41 μA.mM-1 and 0.41 μM for gCNQDs-CoPc (premixed) and 100.5 μA.mM-1 and 0.02 μM for gCNQDs-CoPc (sequential). The electrode surfaces also showed high stability by continuous cyclization.
- Full Text:
- Date Issued: 2019
- Authors: Nxele, Siphesihle R , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186746 , vital:44530 , xlink:href="https://doi.org/10.1016/j.electacta.2019.134978"
- Description: This work reports for the first time on the use of a conjugate of graphitic carbon nitride quantum dots (gCNQDs) with a push-pull asymmetrical cobalt phthalocyanine (CoPc) for electrochemical sensing. The nanocomposite is immobilized on a glassy carbon electrode (GCE) surface for the use in l-cysteine electrocatalysis. The nanocomposites were characterized using techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Raman spectroscopy and electrochemical methods. The nanocomposites were immobilized by the drop-dry method, sequentially or when premixed in solution. Good electrocatalytic oxidation of l-cysteine was observed, especially by the sequentially modified electrode surface, with the CoPc on top of gCNQDs. The sensitivity was determined as 3.5 μA.mM-1 and the limit of detection (LoD) as 101.3 μM for GCE-gCNQDs, 0.65 μA.mM-1 and 0.96 μM for GCE-CoPc, 23.41 μA.mM-1 and 0.41 μM for gCNQDs-CoPc (premixed) and 100.5 μA.mM-1 and 0.02 μM for gCNQDs-CoPc (sequential). The electrode surfaces also showed high stability by continuous cyclization.
- Full Text:
- Date Issued: 2019
Photophysicochemical properties of nanoconjugates of zinc (II) 2 (3)-mono-2-(4-oxy) phenoxy) acetic acid phthalocyanine with cysteamine capped silver and silver–gold nanoparticles
- Oluwole, David O, Prinsloo, Earl, Nyokong, Tebello
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188552 , vital:44764 , xlink:href="https://doi.org/10.1016/j.poly.2016.09.034"
- Description: A novel asymmetrical zinc(II) 2(3)-mono-2-(4-oxy)phenoxy)acetic acid phthalocyanine (complex 1) was synthesized and subsequently linked to cysteamine capped silver (AgNPs) and silver–gold (AgAuNPs) nanoparticles (NPs) via amide bonds. The photophysicochemical properties and in vitro photodynamic therapy activity of complex 1 and its nanoconjugates were investigated. The nanoconjugates showed improved photophysical properties compared to complex 1 alone. The fluorescence, triplet and singlet quantum yields of complex 1 were found to be 20%, 48%, and 43% respectively. Complex 1 showed in vitro dark cytotoxicity, but the dark toxicity was reduced for the combination of complex 1 with AgAuNPs, this combination also gave the best photodynamic therapy activity when compared to complex 1 and its conjugate with AgNPs without AuNPs.
- Full Text:
- Date Issued: 2016
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188552 , vital:44764 , xlink:href="https://doi.org/10.1016/j.poly.2016.09.034"
- Description: A novel asymmetrical zinc(II) 2(3)-mono-2-(4-oxy)phenoxy)acetic acid phthalocyanine (complex 1) was synthesized and subsequently linked to cysteamine capped silver (AgNPs) and silver–gold (AgAuNPs) nanoparticles (NPs) via amide bonds. The photophysicochemical properties and in vitro photodynamic therapy activity of complex 1 and its nanoconjugates were investigated. The nanoconjugates showed improved photophysical properties compared to complex 1 alone. The fluorescence, triplet and singlet quantum yields of complex 1 were found to be 20%, 48%, and 43% respectively. Complex 1 showed in vitro dark cytotoxicity, but the dark toxicity was reduced for the combination of complex 1 with AgAuNPs, this combination also gave the best photodynamic therapy activity when compared to complex 1 and its conjugate with AgNPs without AuNPs.
- Full Text:
- Date Issued: 2016