Remedies, repentance and the doctrine of election in South African contract law
- Authors: Glover, Graham
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186712 , vital:44527 , xlink:href="https://hdl.handle.net/10520/EJC-1a756528b2"
- Description: One of the main features of South Africa’s law on remedies for breach of contract is the doctrine of election. In cases where a major breach has occurred, or a cancellation clause entitles the aggrieved party to seek cancellation, the aggrieved party has an election either to cancel or to claim performance, and will be held to that binary choice. In Primat Construction CC v Nelson Mandela Bay Metropolitan Municipality the Supreme Court of Appeal recently recognised an exception to the usual election rule, specifically in cases involving repudiation. In terms of the ‘repentance principle’, a party who experiences repudiation may initially seek performance in the hope that the breaching party will repent of their breach; but if it does not, the aggrieved party may then change its mind and seek cancellation. This essay considers the history of the doctrine of election and the path to the recognition of its qualifier, the repentance principle. Thereafter, the essay poses the question whether it remains desirable for the strict doctrine of election to continue to apply in South African law, bearing in mind that a strict election can have an unduly constraining effect on the interests of the non-breaching (or ‘innocent’) party. This analysis is informed by the broader policy considerations behind the recognition of the repentance principle; the fact that other analogous exceptions to the election rule do exist; and the fact that other jurisdictions do not adopt such a strict approach to the aggrieved party’s choice of remedy.
- Full Text:
- Date Issued: 2019
- Authors: Glover, Graham
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186712 , vital:44527 , xlink:href="https://hdl.handle.net/10520/EJC-1a756528b2"
- Description: One of the main features of South Africa’s law on remedies for breach of contract is the doctrine of election. In cases where a major breach has occurred, or a cancellation clause entitles the aggrieved party to seek cancellation, the aggrieved party has an election either to cancel or to claim performance, and will be held to that binary choice. In Primat Construction CC v Nelson Mandela Bay Metropolitan Municipality the Supreme Court of Appeal recently recognised an exception to the usual election rule, specifically in cases involving repudiation. In terms of the ‘repentance principle’, a party who experiences repudiation may initially seek performance in the hope that the breaching party will repent of their breach; but if it does not, the aggrieved party may then change its mind and seek cancellation. This essay considers the history of the doctrine of election and the path to the recognition of its qualifier, the repentance principle. Thereafter, the essay poses the question whether it remains desirable for the strict doctrine of election to continue to apply in South African law, bearing in mind that a strict election can have an unduly constraining effect on the interests of the non-breaching (or ‘innocent’) party. This analysis is informed by the broader policy considerations behind the recognition of the repentance principle; the fact that other analogous exceptions to the election rule do exist; and the fact that other jurisdictions do not adopt such a strict approach to the aggrieved party’s choice of remedy.
- Full Text:
- Date Issued: 2019
Research for the people, by the people: The political practice of cognitive justice and transformative learning in environmental social movements
- Authors: Burt, Jane C
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392177 , vital:68728 , xlink:href="https://doi.org/10.3390/su11205611"
- Description: This paper describes how Changing Practice courses, developed by environmental activists in South Africa and based on social learning practice, have seeded cognitive justice action. For the educator-activists who facilitated these courses, it became apparent that we needed a bold emancipatory pedagogy which included cognitive justice issues. This enabled us and the activist-researcher participants to understand the extent to which local, indigenous, and spiritual knowledge had been excluded from water governance. The paper investigates how participants in the ‘Water and Tradition’ change project, established by the Vaal Environmental Justice Alliance (VEJA, engaged with cognitive justice, to demonstrate how African spiritual practice offers a re-visioning of the natural world. Finally, using the tools of critical realist theory, the paper reviews how VEJA bring about transformative social action through their participation in the Changing Practice course.
- Full Text:
- Date Issued: 2019
- Authors: Burt, Jane C
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392177 , vital:68728 , xlink:href="https://doi.org/10.3390/su11205611"
- Description: This paper describes how Changing Practice courses, developed by environmental activists in South Africa and based on social learning practice, have seeded cognitive justice action. For the educator-activists who facilitated these courses, it became apparent that we needed a bold emancipatory pedagogy which included cognitive justice issues. This enabled us and the activist-researcher participants to understand the extent to which local, indigenous, and spiritual knowledge had been excluded from water governance. The paper investigates how participants in the ‘Water and Tradition’ change project, established by the Vaal Environmental Justice Alliance (VEJA, engaged with cognitive justice, to demonstrate how African spiritual practice offers a re-visioning of the natural world. Finally, using the tools of critical realist theory, the paper reviews how VEJA bring about transformative social action through their participation in the Changing Practice course.
- Full Text:
- Date Issued: 2019
Risk assessment to interpret the physiological host range of Hydrellia egeriae, a biocontrol agent for Egeria densa
- Smith, Rosalie, Mangan, Rosie, Coetzee, Julie A
- Authors: Smith, Rosalie , Mangan, Rosie , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/418053 , vital:71504 , xlink:href="https://doi.org/10.1007/s10526-019-09942-4"
- Description: Egeria densa Planchon (Hydrocharitaceae) is a submerged macrophyte native to South America. It forms part of a new suite of invasive aquatic plants that has benefited from open nutrient-rich freshwater systems following the successful biological control of floating aquatic plants in South Africa. The specificity of the leaf-mining fly, Hydrellia egeriae Rodrigues (Diptera: Ephydridae) was tested, using traditional laboratory host-specificity testing (i.e., no-choice and paired choice). Only one non-target species, Lagarosiphon major Deeming (Hydrocharitaceae) supported larval development during pair-choice tests. In order to avoid the rejection of a safe and potentially effective agent, continuation (i.e., multiple generations) tests were conducted to measure the ability of the non-target species to nutritionally support a population indefinitely. None of these species could sustain a viable agent population for more than three generations. Laboratory host-specificity tests are limited as they exempt certain insect-host behaviours. To enhance the interpretation of host-specificity results, a risk assessment was conducted using agent preference (i.e., choice tests) and performance (i.e., choice and continuation tests) results. The feeding and reproductive risk that H. egeriae poses to non-target species is below 2%. Based on these findings, permission for its release in South Africa has been obtained.
- Full Text:
- Date Issued: 2019
- Authors: Smith, Rosalie , Mangan, Rosie , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/418053 , vital:71504 , xlink:href="https://doi.org/10.1007/s10526-019-09942-4"
- Description: Egeria densa Planchon (Hydrocharitaceae) is a submerged macrophyte native to South America. It forms part of a new suite of invasive aquatic plants that has benefited from open nutrient-rich freshwater systems following the successful biological control of floating aquatic plants in South Africa. The specificity of the leaf-mining fly, Hydrellia egeriae Rodrigues (Diptera: Ephydridae) was tested, using traditional laboratory host-specificity testing (i.e., no-choice and paired choice). Only one non-target species, Lagarosiphon major Deeming (Hydrocharitaceae) supported larval development during pair-choice tests. In order to avoid the rejection of a safe and potentially effective agent, continuation (i.e., multiple generations) tests were conducted to measure the ability of the non-target species to nutritionally support a population indefinitely. None of these species could sustain a viable agent population for more than three generations. Laboratory host-specificity tests are limited as they exempt certain insect-host behaviours. To enhance the interpretation of host-specificity results, a risk assessment was conducted using agent preference (i.e., choice tests) and performance (i.e., choice and continuation tests) results. The feeding and reproductive risk that H. egeriae poses to non-target species is below 2%. Based on these findings, permission for its release in South Africa has been obtained.
- Full Text:
- Date Issued: 2019
Short term stability testing of efavirenz-loaded solid lipid nanoparticle (SLN) and nanostructured lipid carrier (NLC) dispersions
- Makoni, Pedzisai A, Kasongo, Kasongo W, Walker, Roderick B
- Authors: Makoni, Pedzisai A , Kasongo, Kasongo W , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183492 , vital:44000 , xlink:href="https://doi.org/10.3390/pharmaceutics11080397"
- Description: The short term stability of efavirenz-loaded solid lipid nanoparticle and nanostructured lipid carrier dispersions was investigated. Hot High Pressure Homogenization with the capability for scale up production was successfully used to manufacture the nanocarriers without the use of toxic organic solvents for the first time. Glyceryl monostearate and Transcutol® HP were used as the solid and liquid lipids. Tween® 80 was used to stabilize the lipid nanocarriers. A Box-Behnken Design was used to identify the optimum operating and production conditions viz., 1100 bar for 3 cycles for the solid lipid nanoparticles and 1500 bar for 5 cycles for nanostructured lipid carriers. The optimized nanocarriers were predicted to exhibit 10% efavirenz loading with 3% and 4% Tween® 80 for solid lipid nanoparticles and nanostructured lipid carriers, respectively. Characterization of the optimized solid lipid nanoparticle and nanostructured lipid carrier formulations in relation to shape, surface morphology, polymorphism, crystallinity and compatibility revealed stable formulations with particle sizes in the nanometer range had been produced. The nanocarriers had excellent efavirenz loading with the encapsulation efficiency >90%. The optimized nanocarriers exhibited biphasic in vitro release patterns with an initial burst release during the initial 0–3 h followed by sustained release over a 24 h period The colloidal systems showed excellent stability in terms of Zeta potential, particle size, polydispersity index and encapsulation efficiency when stored for 8 weeks at 25 °C/60% RH in comparison to when stored at 40 °C/75% RH. The formulations manufactured using the optimized conditions and composition proved to be physically stable as aqueous dispersions.
- Full Text:
- Date Issued: 2019
- Authors: Makoni, Pedzisai A , Kasongo, Kasongo W , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183492 , vital:44000 , xlink:href="https://doi.org/10.3390/pharmaceutics11080397"
- Description: The short term stability of efavirenz-loaded solid lipid nanoparticle and nanostructured lipid carrier dispersions was investigated. Hot High Pressure Homogenization with the capability for scale up production was successfully used to manufacture the nanocarriers without the use of toxic organic solvents for the first time. Glyceryl monostearate and Transcutol® HP were used as the solid and liquid lipids. Tween® 80 was used to stabilize the lipid nanocarriers. A Box-Behnken Design was used to identify the optimum operating and production conditions viz., 1100 bar for 3 cycles for the solid lipid nanoparticles and 1500 bar for 5 cycles for nanostructured lipid carriers. The optimized nanocarriers were predicted to exhibit 10% efavirenz loading with 3% and 4% Tween® 80 for solid lipid nanoparticles and nanostructured lipid carriers, respectively. Characterization of the optimized solid lipid nanoparticle and nanostructured lipid carrier formulations in relation to shape, surface morphology, polymorphism, crystallinity and compatibility revealed stable formulations with particle sizes in the nanometer range had been produced. The nanocarriers had excellent efavirenz loading with the encapsulation efficiency >90%. The optimized nanocarriers exhibited biphasic in vitro release patterns with an initial burst release during the initial 0–3 h followed by sustained release over a 24 h period The colloidal systems showed excellent stability in terms of Zeta potential, particle size, polydispersity index and encapsulation efficiency when stored for 8 weeks at 25 °C/60% RH in comparison to when stored at 40 °C/75% RH. The formulations manufactured using the optimized conditions and composition proved to be physically stable as aqueous dispersions.
- Full Text:
- Date Issued: 2019
Simulated global increases in atmospheric CO2 alter the tissue composition, but not the growth of some submerged aquatic plant bicarbonate users growing in DIC rich waters
- Hussner, Andreas, Smith, Rosali, Mettler-Altmann, Tabea, Hill, Martin P, Coetzee, Julie A
- Authors: Hussner, Andreas , Smith, Rosali , Mettler-Altmann, Tabea , Hill, Martin P , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419388 , vital:71640 , xlink:href="https://doi.org/10.1016/j.aquabot.2018.11.009"
- Description: Current global change scenarios predict an increase in atmospheric CO2 from the current 380 ppm to a value ranging from 540 ppm to 960 ppm by the year 2100. The effects of three air CO2 levels (400, 600 and 800 ppm) on five submerged aquatic plants that utilize HCO3− were studied, using the elevated CO2 Open Top Chamber facility at Rhodes University (Grahamstown, South Africa). Plants grew in water with two different initial dissolved inorganic carbon (DIC) concentrations of 1.5 and 3.0 mM. Overall, the growth rates and biomass allocation to roots were not affected by the initial DIC and air CO2, even though differences between the species were found. Furthermore, no overall effects were found on net photosynthesis, chlorophyll and starch content, even though significant effects of CO2 and DIC were observed in some species. In contrast, with increasing DIC and air CO2 a significant global decline in leaf nitrogen content linked with an increased C:N molar ratio was observed. The results indicate that submerged aquatic HCO3− users will be less affected by atmospheric CO2 increases when growing in DIC rich waters, in comparison to obligate CO2 users growing under CO2 limiting conditions as documented in previous studies. However, the changes found in plant nitrogen illustrate that atmospheric CO2 increases will affect nitrogen absorption by submerged plants, with subsequent ecosystem level effects.
- Full Text:
- Date Issued: 2019
- Authors: Hussner, Andreas , Smith, Rosali , Mettler-Altmann, Tabea , Hill, Martin P , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419388 , vital:71640 , xlink:href="https://doi.org/10.1016/j.aquabot.2018.11.009"
- Description: Current global change scenarios predict an increase in atmospheric CO2 from the current 380 ppm to a value ranging from 540 ppm to 960 ppm by the year 2100. The effects of three air CO2 levels (400, 600 and 800 ppm) on five submerged aquatic plants that utilize HCO3− were studied, using the elevated CO2 Open Top Chamber facility at Rhodes University (Grahamstown, South Africa). Plants grew in water with two different initial dissolved inorganic carbon (DIC) concentrations of 1.5 and 3.0 mM. Overall, the growth rates and biomass allocation to roots were not affected by the initial DIC and air CO2, even though differences between the species were found. Furthermore, no overall effects were found on net photosynthesis, chlorophyll and starch content, even though significant effects of CO2 and DIC were observed in some species. In contrast, with increasing DIC and air CO2 a significant global decline in leaf nitrogen content linked with an increased C:N molar ratio was observed. The results indicate that submerged aquatic HCO3− users will be less affected by atmospheric CO2 increases when growing in DIC rich waters, in comparison to obligate CO2 users growing under CO2 limiting conditions as documented in previous studies. However, the changes found in plant nitrogen illustrate that atmospheric CO2 increases will affect nitrogen absorption by submerged plants, with subsequent ecosystem level effects.
- Full Text:
- Date Issued: 2019
Spectroscopic and nonlinear optical properties of alkyl thio substituted binuclear phthalocyanines
- Makinde, Zainab O, Louzada, Marcel S, Britton, Jonathan, Nyokong, Tebello, Khene, Samson M
- Authors: Makinde, Zainab O , Louzada, Marcel S , Britton, Jonathan , Nyokong, Tebello , Khene, Samson M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187485 , vital:44661 , xlink:href="https://doi.org/10.1016/j.dyepig.2018.10.022"
- Description: This work presents the spectroscopic and nonlinear optical properties of metal free binuclear and monomeric 4- (pentylthio)phthalocyanine and cobalt 4,5-(bipentylthio)phthalocyanine. Second order nonlinear absorption coefficient (β) values for the complexes were determined and compared.
- Full Text:
- Date Issued: 2019
- Authors: Makinde, Zainab O , Louzada, Marcel S , Britton, Jonathan , Nyokong, Tebello , Khene, Samson M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187485 , vital:44661 , xlink:href="https://doi.org/10.1016/j.dyepig.2018.10.022"
- Description: This work presents the spectroscopic and nonlinear optical properties of metal free binuclear and monomeric 4- (pentylthio)phthalocyanine and cobalt 4,5-(bipentylthio)phthalocyanine. Second order nonlinear absorption coefficient (β) values for the complexes were determined and compared.
- Full Text:
- Date Issued: 2019
Spectroscopic characterization and photodynamic antimicrobial chemotherapy of phthalocyanine-silver triangular nanoprism conjugates when supported on asymmetric polymer membranes
- Mafukidze, Donovan M, Sindelo, Azole, Nyokong, Tebello
- Authors: Mafukidze, Donovan M , Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186927 , vital:44548 , xlink:href="https://doi.org/10.1016/j.saa.2019.04.054"
- Description: Silver triangular nanoprisms were synthesized and conjugated to zinc (ZnPc) and indium (InPc) phthalocyanines prior to embedding in asymmetric membranes. Conjugation of nanoparticles increased triplet state and singlet oxygen quantum yields of the phthalocyanines as well as enhancing photodynamic antimicrobial chemotherapy (PACT) activity against bacteria (S. aureus). The ZnPc derivative showed higher PACT activity when compared to the InPc, possibly due to degradation of the latter in aqueous media.
- Full Text:
- Date Issued: 2019
- Authors: Mafukidze, Donovan M , Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186927 , vital:44548 , xlink:href="https://doi.org/10.1016/j.saa.2019.04.054"
- Description: Silver triangular nanoprisms were synthesized and conjugated to zinc (ZnPc) and indium (InPc) phthalocyanines prior to embedding in asymmetric membranes. Conjugation of nanoparticles increased triplet state and singlet oxygen quantum yields of the phthalocyanines as well as enhancing photodynamic antimicrobial chemotherapy (PACT) activity against bacteria (S. aureus). The ZnPc derivative showed higher PACT activity when compared to the InPc, possibly due to degradation of the latter in aqueous media.
- Full Text:
- Date Issued: 2019
Stability indicating HPLC-ECD method for the analysis of clarithromycin in pharmaceutical dosage forms: Method scaling versus re-validation.
- Makoni, Pedzisai A, Chikukwa, Mellisa, Khamanga, Sandile M, Walker, Roderick B
- Authors: Makoni, Pedzisai A , Chikukwa, Mellisa , Khamanga, Sandile M , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183387 , vital:43984 , xlink:href="https://doi.org/10.3390/scipharm87040031"
- Description: An isocratic high-performance liquid chromatographic method using electrochemical detection (HPLC-ECD) for the quantitation of clarithromycin (CLA) was developed using Response Surface Methodology (RSM) based on a Central Composite Design (CCD). The method was validated using International Conference on Harmonization (ICH) guidelines with an analytical run time of 20 min. Method re-validation following a change in analytical column was successful in reducing the analytical run time to 13 min, decreasing solvent consumption thus facilitating environmental and financial sustainability. The applicability of using the United States Pharmacopeia (USP) method scaling approach in place of method re-validation using a column with a different L–designation to the original analytical column, was investigated. The scaled method met all USP system suitability requirements for resolution, tailing factor and % relative standard deviation (RSD). The re-validated and scaled method was successfully used to resolve CLA from manufacturing excipients in commercially available dosage forms. Although USP method scaling is only permitted for columns within the same L-designation, these data suggest that it may also be applicable to columns of different designation.
- Full Text:
- Date Issued: 2019
- Authors: Makoni, Pedzisai A , Chikukwa, Mellisa , Khamanga, Sandile M , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183387 , vital:43984 , xlink:href="https://doi.org/10.3390/scipharm87040031"
- Description: An isocratic high-performance liquid chromatographic method using electrochemical detection (HPLC-ECD) for the quantitation of clarithromycin (CLA) was developed using Response Surface Methodology (RSM) based on a Central Composite Design (CCD). The method was validated using International Conference on Harmonization (ICH) guidelines with an analytical run time of 20 min. Method re-validation following a change in analytical column was successful in reducing the analytical run time to 13 min, decreasing solvent consumption thus facilitating environmental and financial sustainability. The applicability of using the United States Pharmacopeia (USP) method scaling approach in place of method re-validation using a column with a different L–designation to the original analytical column, was investigated. The scaled method met all USP system suitability requirements for resolution, tailing factor and % relative standard deviation (RSD). The re-validated and scaled method was successfully used to resolve CLA from manufacturing excipients in commercially available dosage forms. Although USP method scaling is only permitted for columns within the same L-designation, these data suggest that it may also be applicable to columns of different designation.
- Full Text:
- Date Issued: 2019
Suicide and the South African business cycle
- Authors: Botha, Ferdi , Pitot, A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396138 , vital:69153 , xlink:href="https://hdl.handle.net/10520/EJC-18880c26e4"
- Description: Using monthly data for January 2006 - December 2015, this study explores the relationship between suicide and the South African business cycle. Contrary to most previous research, the findings reveal that suicide is pro-cyclical.
- Full Text:
- Date Issued: 2019
- Authors: Botha, Ferdi , Pitot, A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396138 , vital:69153 , xlink:href="https://hdl.handle.net/10520/EJC-18880c26e4"
- Description: Using monthly data for January 2006 - December 2015, this study explores the relationship between suicide and the South African business cycle. Contrary to most previous research, the findings reveal that suicide is pro-cyclical.
- Full Text:
- Date Issued: 2019
Synthesis and photophysicochemical properties of novel axially di-substituted silicon (IV) phthalocyanines and their photodynamic antimicrobial chemotherapy (PACT) activity against Staphylococcus aureus
- Sen, Pinar, Sindelo, Azole, Mafukidze, Donovan M, Nyokong, Tebello
- Authors: Sen, Pinar , Sindelo, Azole , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186757 , vital:44531 , xlink:href="https://doi.org/10.1016/j.synthmet.2019.116203"
- Description: In this study, novel silicon (IV) phthalocyanine axially di-substituted with benzimidazole moieties (3) and its quaternized derivative (4) have been synthesized and fully characterized. The photophysical and photochemical properties of both phthalocyanines such as absorption, fluorescence and, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were investigated in solutions. These new silicon phthalocyanines exhibited low fluorescence but produced high singlet oxygen yields in both DMSO (compound 3 and 4) and aqueous media (compound 4). The quaternization of Si(IV)Pc (3) improved the triplet state quantum yield (ΦT) 0.61 to 0.83, consequently singlet oxygen generation (ΦΔ) increased to 0.69 from 0.42. Photodynamic antimicrobial chemotherapy activities (PACT) of Si(IV)Pc photosensitizers were determined towards Staphylococcus aureus. The higher efficiency was obtained with cationic derivative (4) giving reduction percentage value of 99.75%.
- Full Text:
- Date Issued: 2019
- Authors: Sen, Pinar , Sindelo, Azole , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186757 , vital:44531 , xlink:href="https://doi.org/10.1016/j.synthmet.2019.116203"
- Description: In this study, novel silicon (IV) phthalocyanine axially di-substituted with benzimidazole moieties (3) and its quaternized derivative (4) have been synthesized and fully characterized. The photophysical and photochemical properties of both phthalocyanines such as absorption, fluorescence and, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were investigated in solutions. These new silicon phthalocyanines exhibited low fluorescence but produced high singlet oxygen yields in both DMSO (compound 3 and 4) and aqueous media (compound 4). The quaternization of Si(IV)Pc (3) improved the triplet state quantum yield (ΦT) 0.61 to 0.83, consequently singlet oxygen generation (ΦΔ) increased to 0.69 from 0.42. Photodynamic antimicrobial chemotherapy activities (PACT) of Si(IV)Pc photosensitizers were determined towards Staphylococcus aureus. The higher efficiency was obtained with cationic derivative (4) giving reduction percentage value of 99.75%.
- Full Text:
- Date Issued: 2019
Synthesis and properties of chiral amide-bonded porphyrin dimers with various functional bridging blocks
- Zhu, Weihua, Haider, Syed Najeeb-uz-Zaman, Zhang, Honglin, Attatsi, Isaac K, Mack, John, Dingiswayo, Somila, Nyokong, Tebello, Song, Yuting, Xu, Haijun, Liang, Xu
- Authors: Zhu, Weihua , Haider, Syed Najeeb-uz-Zaman , Zhang, Honglin , Attatsi, Isaac K , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Song, Yuting , Xu, Haijun , Liang, Xu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186791 , vital:44534 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107740"
- Description: Eight porphyrin dimers with various functional bridging blocks and chiral amide-bonds were synthesized and characterized. An analysis of the spectroscopy and electrochemistry has been carried out to demonstrate that the chiral properties can be modified by changing the interchromophoric through-space coupling distance between the two porphyrin chromophores by introducing various bonding and bridging blocks.
- Full Text:
- Date Issued: 2019
- Authors: Zhu, Weihua , Haider, Syed Najeeb-uz-Zaman , Zhang, Honglin , Attatsi, Isaac K , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Song, Yuting , Xu, Haijun , Liang, Xu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186791 , vital:44534 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107740"
- Description: Eight porphyrin dimers with various functional bridging blocks and chiral amide-bonds were synthesized and characterized. An analysis of the spectroscopy and electrochemistry has been carried out to demonstrate that the chiral properties can be modified by changing the interchromophoric through-space coupling distance between the two porphyrin chromophores by introducing various bonding and bridging blocks.
- Full Text:
- Date Issued: 2019
Synthesis, characterization and photodynamic activity of Sn (iv) triarylcorroles with red-shifted Q bands
- Babu, Balaji, Prinsloo, Earl, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Prinsloo, Earl , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187521 , vital:44668 , xlink:href="https://doi.org/10.1039/C9NJ03391B"
- Description: Two Sn(IV) triarylcorroles were synthesised and characterized. The absorption spectrum of a meso-thien-2-yl substituted tin(IV)corrole (1-Sn) is red shifted compared to its phenyl analogue (2-Sn) and shows no sign of aggregation in solution. 1-Sn and 2-Sn exhibited singlet oxygen quantum yields of 0.87 and 0.54 in DMF, and have a triplet lifetime of 31 and 50 μs, respectively. Time dependent cellular uptake in MCF-7 cells for 1-Sn reached a peak at 24 h, and 1-Sn was found to be more lipophilic than 2-Sn. 1-Sn showed good photo-cytotoxicity on exposure to a Thorlabs 625 nm LED with an IC50 value of 3.2 μM and remained inactive in the dark.
- Full Text:
- Date Issued: 2019
- Authors: Babu, Balaji , Prinsloo, Earl , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187521 , vital:44668 , xlink:href="https://doi.org/10.1039/C9NJ03391B"
- Description: Two Sn(IV) triarylcorroles were synthesised and characterized. The absorption spectrum of a meso-thien-2-yl substituted tin(IV)corrole (1-Sn) is red shifted compared to its phenyl analogue (2-Sn) and shows no sign of aggregation in solution. 1-Sn and 2-Sn exhibited singlet oxygen quantum yields of 0.87 and 0.54 in DMF, and have a triplet lifetime of 31 and 50 μs, respectively. Time dependent cellular uptake in MCF-7 cells for 1-Sn reached a peak at 24 h, and 1-Sn was found to be more lipophilic than 2-Sn. 1-Sn showed good photo-cytotoxicity on exposure to a Thorlabs 625 nm LED with an IC50 value of 3.2 μM and remained inactive in the dark.
- Full Text:
- Date Issued: 2019
Testing the thermal limits of Eccritotarsus catarinensis: a case of thermal plasticity
- Porter, Jordan D, Owen, Candice A, Compton, Stephen G, Coetzee, Julie A
- Authors: Porter, Jordan D , Owen, Candice A , Compton, Stephen G , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417533 , vital:71461 , xlink:href="https://doi.org/10.1080/09583157.2019.1572712"
- Description: Water hyacinth is considered the most damaging aquatic weed in South Africa. The success of biocontrol initiatives against the weed varies nation-wide, but control remains generally unattainable in higher altitude, temperate regions. Eccritotarsus catarinensis (Hemiptera: Miridae) is a biocontrol agent of water hyacinth that was first released in South Africa in 1996. By 2011, it was established at over 30 sites across the country. These include the Kubusi River, a site with a temperate climate where agent establishment and persistence was unexpected. This study compared the critical thermal limits of the Kubusi River insect population with a laboratory-reared culture to determine whether any physiological plasticity was evident that could account for its unexpected establishment. There were no significant differences in critical thermal maxima (CTmax) or minima (CTmin) between sexes, while the effect of rate of temperature change on the thermal parameters in the experiments had a significant impact in some trials. Both CTmax and CTmin differed significantly between the two populations, with the field individuals tolerating significantly lower temperatures (CTmin: −0.3°C ± 0.063 [SE], CTmax: 42.8°C ± 0.155 [SE]) than those maintained in the laboratory (CTmin: 1.1°C ± 0.054 [SE], CTmax: 44.9°C ± 0.196 [SE]). Acclimation of each population to the environmental conditions typical of the other for a five-day period illustrated that short-term acclimation accounted for some, but not all of the variation between their lower thermal limits. This study provides evidence for the first cold-adapted strain of E. catarinensis in the field, with potential value for introduction into other colder regions where water hyacinth control is currently unattainable.
- Full Text:
- Date Issued: 2019
- Authors: Porter, Jordan D , Owen, Candice A , Compton, Stephen G , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417533 , vital:71461 , xlink:href="https://doi.org/10.1080/09583157.2019.1572712"
- Description: Water hyacinth is considered the most damaging aquatic weed in South Africa. The success of biocontrol initiatives against the weed varies nation-wide, but control remains generally unattainable in higher altitude, temperate regions. Eccritotarsus catarinensis (Hemiptera: Miridae) is a biocontrol agent of water hyacinth that was first released in South Africa in 1996. By 2011, it was established at over 30 sites across the country. These include the Kubusi River, a site with a temperate climate where agent establishment and persistence was unexpected. This study compared the critical thermal limits of the Kubusi River insect population with a laboratory-reared culture to determine whether any physiological plasticity was evident that could account for its unexpected establishment. There were no significant differences in critical thermal maxima (CTmax) or minima (CTmin) between sexes, while the effect of rate of temperature change on the thermal parameters in the experiments had a significant impact in some trials. Both CTmax and CTmin differed significantly between the two populations, with the field individuals tolerating significantly lower temperatures (CTmin: −0.3°C ± 0.063 [SE], CTmax: 42.8°C ± 0.155 [SE]) than those maintained in the laboratory (CTmin: 1.1°C ± 0.054 [SE], CTmax: 44.9°C ± 0.196 [SE]). Acclimation of each population to the environmental conditions typical of the other for a five-day period illustrated that short-term acclimation accounted for some, but not all of the variation between their lower thermal limits. This study provides evidence for the first cold-adapted strain of E. catarinensis in the field, with potential value for introduction into other colder regions where water hyacinth control is currently unattainable.
- Full Text:
- Date Issued: 2019
The attitudes of riparian communities to the presence of water hyacinth in the Wouri River Basin, Douala, Cameroon
- Voukeng, Kenfack S N, Weyl, Philip, Hill, Martin P, Chi, N
- Authors: Voukeng, Kenfack S N , Weyl, Philip , Hill, Martin P , Chi, N
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423822 , vital:72096 , xlink:href="https://doi.org/10.2989/16085914.2018.1538868"
- Description: Since publication of the first record of Eichhornia crassipes in Cameroon in 1997, the weed has become highly invasive in the Wouri River Basin. Between June and September 2014, a socio-economic survey using participatory and qualitative methods was undertaken in the riparian villages of the Wouri River Basin to assess the perception of respondents to the presence of water hyacinth. The survey revealed that water hyacinth was a significant threat to activities along the river, which included fishing, sand extraction and river transportation. The presence of water hyacinth mats reduced catch rates of several common fish species, river transportation by 75%, and significantly reduced the income for sand extraction. Cameroon employs manual clearing of water hyacinth; however, respondents indicated they would consider other control methods, provided they do not have any negative impacts.
- Full Text:
- Date Issued: 2019
- Authors: Voukeng, Kenfack S N , Weyl, Philip , Hill, Martin P , Chi, N
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423822 , vital:72096 , xlink:href="https://doi.org/10.2989/16085914.2018.1538868"
- Description: Since publication of the first record of Eichhornia crassipes in Cameroon in 1997, the weed has become highly invasive in the Wouri River Basin. Between June and September 2014, a socio-economic survey using participatory and qualitative methods was undertaken in the riparian villages of the Wouri River Basin to assess the perception of respondents to the presence of water hyacinth. The survey revealed that water hyacinth was a significant threat to activities along the river, which included fishing, sand extraction and river transportation. The presence of water hyacinth mats reduced catch rates of several common fish species, river transportation by 75%, and significantly reduced the income for sand extraction. Cameroon employs manual clearing of water hyacinth; however, respondents indicated they would consider other control methods, provided they do not have any negative impacts.
- Full Text:
- Date Issued: 2019
The contribution of land tenure diversity to the spatial resilience of protected area networks
- de Vos, Alta, Cumming, George S
- Authors: de Vos, Alta , Cumming, George S
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416421 , vital:71347 , xlink:href="https://doi.org/10.1002/pan3.29"
- Description: The relationship between diversity and resilience is relatively well‐established for ecological systems, but remains much less explored for socio‐economic systems. Institutional diversity can have particular relevance for protected areas, whose managerial responses to environmental change depend on their legal basis, ability to make and enforce rules and socio‐political acceptance and endorsement. 2. Protected area expansion strategies are increasingly turning to private land con‐ servation to increase the configuration and connectivity of national protected area networks. Yet, we know little about the relative role of privately owned pro‐ tected areas in protecting threatened and poorly protected (under‐represented) habitats, and in the overall connectivity of the national protected area network. 3. We present an empirical assessment of protected area tenure diversity across South Africa.
- Full Text:
- Date Issued: 2019
- Authors: de Vos, Alta , Cumming, George S
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416421 , vital:71347 , xlink:href="https://doi.org/10.1002/pan3.29"
- Description: The relationship between diversity and resilience is relatively well‐established for ecological systems, but remains much less explored for socio‐economic systems. Institutional diversity can have particular relevance for protected areas, whose managerial responses to environmental change depend on their legal basis, ability to make and enforce rules and socio‐political acceptance and endorsement. 2. Protected area expansion strategies are increasingly turning to private land con‐ servation to increase the configuration and connectivity of national protected area networks. Yet, we know little about the relative role of privately owned pro‐ tected areas in protecting threatened and poorly protected (under‐represented) habitats, and in the overall connectivity of the national protected area network. 3. We present an empirical assessment of protected area tenure diversity across South Africa.
- Full Text:
- Date Issued: 2019
The contribution of NTFPs to rural livelihoods in different agro-ecological zones of South Africa
- Mugido, Worship, Shackleton, Charlie M
- Authors: Mugido, Worship , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182308 , vital:43819 , xlink:href="Commonwealth Forestry Association"
- Description: In South Africa, there is extensive NTFP trade within communities and via external markets. However, there is a limited indication of the proportion of all households trading one or more NTFPs, and how it varies in relation to local context. Therefore, this study sought to establish the proportion of households trading in NTFPs in sites of different distances to urban markets and agro-ecological zones of South Africa. The results showed that about 6.4% households reported selling NTFPs for various reasons, with many (22%) citing the need to earn cash income and limited employment opportunities (16.9%). Even though the returns from trading NTFPs are relatively low, every earning is very important to many cash-strapped rural households. This was demonstrated by the fact that many sellers of NTFPs used their earnings to augment household income and cover their living expenses.
- Full Text:
- Date Issued: 2019
- Authors: Mugido, Worship , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182308 , vital:43819 , xlink:href="Commonwealth Forestry Association"
- Description: In South Africa, there is extensive NTFP trade within communities and via external markets. However, there is a limited indication of the proportion of all households trading one or more NTFPs, and how it varies in relation to local context. Therefore, this study sought to establish the proportion of households trading in NTFPs in sites of different distances to urban markets and agro-ecological zones of South Africa. The results showed that about 6.4% households reported selling NTFPs for various reasons, with many (22%) citing the need to earn cash income and limited employment opportunities (16.9%). Even though the returns from trading NTFPs are relatively low, every earning is very important to many cash-strapped rural households. This was demonstrated by the fact that many sellers of NTFPs used their earnings to augment household income and cover their living expenses.
- Full Text:
- Date Issued: 2019
The meaning and practice of stewardship in South Africa
- Cockburn, Jessica, Cundill, Georgina, Shackleton, Sheona, Rouget, Mathieu
- Authors: Cockburn, Jessica , Cundill, Georgina , Shackleton, Sheona , Rouget, Mathieu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390683 , vital:68574 , xlink:href="http://dx.doi.org/10.17159/sajs.2019/5339"
- Description: Stewardship offers a means of addressing social-ecological sustainability challenges, from the local to the global level. The concept of stewardship has had various meanings attached to it over time, and the links between the theory and practice of stewardship are not well understood. We sought to characterise the practice of stewardship in South Africa, to better understand the relationship between theory and practice. We found that practitioners’ understandings of stewardship coalesce around two core notions: the idea of stewardship as ‘responsible use and care’ of nature, and stewardship as a ‘balancing act’ between stewards’ use of natural resources for agricultural production and their responsibility to protect and manage the wider ecosystem. Stewardship practice in South Africa is strongly influenced by the biodiversity stewardship tool; however, many practitioners are integrating biodiversity stewardship with other approaches. These emerging social-ecological stewardship initiatives operate at landscape-level and work towards integrated social and ecological stewardship outcomes, by facilitating collaboration among diverse stakeholders. Further research is needed to better understand what is required to support these integrated, collaborative and cross-sectoral initiatives. Policy mechanisms that facilitate integrated place-based stewardship practice can contribute to expanding the practice of biodiversity stewardship in South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Cockburn, Jessica , Cundill, Georgina , Shackleton, Sheona , Rouget, Mathieu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390683 , vital:68574 , xlink:href="http://dx.doi.org/10.17159/sajs.2019/5339"
- Description: Stewardship offers a means of addressing social-ecological sustainability challenges, from the local to the global level. The concept of stewardship has had various meanings attached to it over time, and the links between the theory and practice of stewardship are not well understood. We sought to characterise the practice of stewardship in South Africa, to better understand the relationship between theory and practice. We found that practitioners’ understandings of stewardship coalesce around two core notions: the idea of stewardship as ‘responsible use and care’ of nature, and stewardship as a ‘balancing act’ between stewards’ use of natural resources for agricultural production and their responsibility to protect and manage the wider ecosystem. Stewardship practice in South Africa is strongly influenced by the biodiversity stewardship tool; however, many practitioners are integrating biodiversity stewardship with other approaches. These emerging social-ecological stewardship initiatives operate at landscape-level and work towards integrated social and ecological stewardship outcomes, by facilitating collaboration among diverse stakeholders. Further research is needed to better understand what is required to support these integrated, collaborative and cross-sectoral initiatives. Policy mechanisms that facilitate integrated place-based stewardship practice can contribute to expanding the practice of biodiversity stewardship in South Africa.
- Full Text:
- Date Issued: 2019
The obstinate notion that higher education is a meritocracy
- Sobuwa, Simpiwe, McKenna, Sioux
- Authors: Sobuwa, Simpiwe , McKenna, Sioux
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187150 , vital:44574 , xlink:href="https://doi.org/10.14426/cristal.v7i2.184"
- Description: Student success is an enormous concern in light of the high drop-out rates in South African universities. There is a wealth of local and international research which provides complex explanations for these statistics, but the common-sense understanding is that those students who have the right attributes and who work hard will do well. While the notion of higher education as a meritocracy is pervasive, it is invalid given the effects of numerous other mechanisms at play in the students' educational experiences. This article draws from the literature to discuss the problems of the meritocratic explanation in how it fails to sufficiently account for the centrality of agency and the ways in which this intersects with societal structures. We argue that more useful understandings of student success and failure require social theory that acknowledges the complexities underpinning student success or failure.
- Full Text:
- Date Issued: 2019
- Authors: Sobuwa, Simpiwe , McKenna, Sioux
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187150 , vital:44574 , xlink:href="https://doi.org/10.14426/cristal.v7i2.184"
- Description: Student success is an enormous concern in light of the high drop-out rates in South African universities. There is a wealth of local and international research which provides complex explanations for these statistics, but the common-sense understanding is that those students who have the right attributes and who work hard will do well. While the notion of higher education as a meritocracy is pervasive, it is invalid given the effects of numerous other mechanisms at play in the students' educational experiences. This article draws from the literature to discuss the problems of the meritocratic explanation in how it fails to sufficiently account for the centrality of agency and the ways in which this intersects with societal structures. We argue that more useful understandings of student success and failure require social theory that acknowledges the complexities underpinning student success or failure.
- Full Text:
- Date Issued: 2019
The photo-physicochemical properties and in vitro photodynamic therapy activity of differently substituted-zinc (II)-phthalocyanines and graphene quantum dots conjugates on MCF7 breast cancer cell line
- Nene, Lindokuhle C, Managa, Muthumuni E, Oluwole, David O, Mafukidze, Donovan M, Sindelo, Azole, Nyokong, Tebello
- Authors: Nene, Lindokuhle C , Managa, Muthumuni E , Oluwole, David O , Mafukidze, Donovan M , Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187449 , vital:44653 , xlink:href="https://doi.org/10.1016/j.ica.2019.01.012"
- Description: Several differently substituted Zn(II) phthalocyanines (ZnPcs) were prepared and conjugated to GQDs. The photophysical properties were determined for both the Pcs and their respective conjugates including the fluorescence/triplet quantum yields and lifetimes as well as the singlet oxygen generating abilities. Upon conjugation to GQDs, the fluorescence of the Pcs decreased (insignificant decrease in some cases), with an increase in the triplet quantum yields. However, the singlet quantum yields of the Pcs in the conjugates did not show an increase with the increase in the triplet quantum yields, this is suspected to be due to the screening effect. The cytotoxicity of the complexes in vitro decreased upon conjugation, as a result of the reduced actual number of Pcs units provided in the conjugate for therapy. Upon introduction of cationic charges, the photodynamic therapy activity of the complexes increased.
- Full Text:
- Date Issued: 2019
- Authors: Nene, Lindokuhle C , Managa, Muthumuni E , Oluwole, David O , Mafukidze, Donovan M , Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187449 , vital:44653 , xlink:href="https://doi.org/10.1016/j.ica.2019.01.012"
- Description: Several differently substituted Zn(II) phthalocyanines (ZnPcs) were prepared and conjugated to GQDs. The photophysical properties were determined for both the Pcs and their respective conjugates including the fluorescence/triplet quantum yields and lifetimes as well as the singlet oxygen generating abilities. Upon conjugation to GQDs, the fluorescence of the Pcs decreased (insignificant decrease in some cases), with an increase in the triplet quantum yields. However, the singlet quantum yields of the Pcs in the conjugates did not show an increase with the increase in the triplet quantum yields, this is suspected to be due to the screening effect. The cytotoxicity of the complexes in vitro decreased upon conjugation, as a result of the reduced actual number of Pcs units provided in the conjugate for therapy. Upon introduction of cationic charges, the photodynamic therapy activity of the complexes increased.
- Full Text:
- Date Issued: 2019
The photophysicochemical properties and photodynamic therapy activity of phenyldiazenyl phenoxy substituted phthalocyanines when incorporated into Pluronic® F127 micelles
- Motloung, Banele M, Sekhosana, Kutloano E, Managa, Muthumuni, Prinsloo, Earl, Nyokong, Tebello
- Authors: Motloung, Banele M , Sekhosana, Kutloano E , Managa, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186769 , vital:44532 , xlink:href="https://doi.org/10.1016/j.poly.2019.114157"
- Description: The synthesis, photophysicochemical properties and photodynamic activity (PDT) of 4(4-phenyldiazenyl) phenoxy substituted indium (III) (InPc) and zinc (ZnPc) phthalocyanines when alone or incorporated into Pluronic_ F127 micelles are presented in this study. The InPc exhibited higher singlet oxygen (UD) at 0.47 compared to the ZnPc at 0.20 in dimethylsulfoxide. The UD values in the presence of Pluronic_ F127 and in water, were 0.32 for InPc and 0.09 for ZnPc. The triplet quantum yields (UT) were 0.92 for InPc and 0.32 for ZnPc in DMSO. The PDT activity followed the same trend as the singlet oxygen quantum yields. At the highest concentration, InPc in Pluronic_ F127 gave 22% cell viability compared to 34% for complex ZnPc. The partition coefficient Kp values were determined using the water and octanol system. InPc had a larger Kp suggesting that it is more likely to be taken up by the cancer cells, hence it exhibited better PDT activity.
- Full Text:
- Date Issued: 2019
- Authors: Motloung, Banele M , Sekhosana, Kutloano E , Managa, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186769 , vital:44532 , xlink:href="https://doi.org/10.1016/j.poly.2019.114157"
- Description: The synthesis, photophysicochemical properties and photodynamic activity (PDT) of 4(4-phenyldiazenyl) phenoxy substituted indium (III) (InPc) and zinc (ZnPc) phthalocyanines when alone or incorporated into Pluronic_ F127 micelles are presented in this study. The InPc exhibited higher singlet oxygen (UD) at 0.47 compared to the ZnPc at 0.20 in dimethylsulfoxide. The UD values in the presence of Pluronic_ F127 and in water, were 0.32 for InPc and 0.09 for ZnPc. The triplet quantum yields (UT) were 0.92 for InPc and 0.32 for ZnPc in DMSO. The PDT activity followed the same trend as the singlet oxygen quantum yields. At the highest concentration, InPc in Pluronic_ F127 gave 22% cell viability compared to 34% for complex ZnPc. The partition coefficient Kp values were determined using the water and octanol system. InPc had a larger Kp suggesting that it is more likely to be taken up by the cancer cells, hence it exhibited better PDT activity.
- Full Text:
- Date Issued: 2019