How good are our guidelines? Four years of experience with the SAMJ’s AGREE II review of submitted clinical practice guidelines
- Kredo, Tamara, Wiseman, Roger, Gray, Andy, Parrish, Andy, Miot, Jacqui, Jamaloodien, Khadija, Blockman, Marc
- Authors: Kredo, Tamara , Wiseman, Roger , Gray, Andy , Parrish, Andy , Miot, Jacqui , Jamaloodien, Khadija , Blockman, Marc
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/5296 , vital:44431 , http://10.7196/SAMJ.2018.v108i11.13646
- Description: The South African Medical Journal (SAMJ) is an established source of clinical practice guidelines (CPGs) serving the local healthcare community. CPGs link professional societies and clinicians by guiding best practice through the collation and interpretation of the best available evidence. Not only are CPGs important in standardising the quality of patient care, but they also assist with medicine selection and resource allocation decisions, adjudicating medicolegal claims, and promoting equity by influencing medicine access and health system organisation.[1] In 2014, the SAMJ appointed an editorial subcommittee to review CPGs submitted for publication.[2] This was in response to several concerns, including the global shift in CPG quality requirements, the potential effect of poor-quality CPGs on healthcare quality and cost, and the challenges South African (SA) CPG developers face in meeting new standards. This editorial reflects on the SAMJ CPG review subcommittee’s experience over the past 4 years and describes the value of more robust CPG development.
- Full Text:
- Date Issued: 2018
- Authors: Kredo, Tamara , Wiseman, Roger , Gray, Andy , Parrish, Andy , Miot, Jacqui , Jamaloodien, Khadija , Blockman, Marc
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/5296 , vital:44431 , http://10.7196/SAMJ.2018.v108i11.13646
- Description: The South African Medical Journal (SAMJ) is an established source of clinical practice guidelines (CPGs) serving the local healthcare community. CPGs link professional societies and clinicians by guiding best practice through the collation and interpretation of the best available evidence. Not only are CPGs important in standardising the quality of patient care, but they also assist with medicine selection and resource allocation decisions, adjudicating medicolegal claims, and promoting equity by influencing medicine access and health system organisation.[1] In 2014, the SAMJ appointed an editorial subcommittee to review CPGs submitted for publication.[2] This was in response to several concerns, including the global shift in CPG quality requirements, the potential effect of poor-quality CPGs on healthcare quality and cost, and the challenges South African (SA) CPG developers face in meeting new standards. This editorial reflects on the SAMJ CPG review subcommittee’s experience over the past 4 years and describes the value of more robust CPG development.
- Full Text:
- Date Issued: 2018
Section 40 of the Consumer Protection Act in comparative perspective: aantekeninge
- Authors: Glover, Graham B
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70527 , vital:29672 , https://hdl.handle.net/10520/EJC144971
- Description: The purpose of this comment is to consider some of the problems with how we are to understand the role and purpose of section 40 of South Africa's Consumer Protection Act 68 of 2008 when viewed from a doctrinal perspective. Section 40 has the heading "Unconscionable conduct", and contains three subsections.
- Full Text: false
- Date Issued: 2013
- Authors: Glover, Graham B
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70527 , vital:29672 , https://hdl.handle.net/10520/EJC144971
- Description: The purpose of this comment is to consider some of the problems with how we are to understand the role and purpose of section 40 of South Africa's Consumer Protection Act 68 of 2008 when viewed from a doctrinal perspective. Section 40 has the heading "Unconscionable conduct", and contains three subsections.
- Full Text: false
- Date Issued: 2013
Leadership Styles and Employee Job Satisfaction: A Case of Head of Departments in Walter Sisulu UniversityMonitoring and Management Mechanisms on Stress in HEI in Eastern Cape Province in South Africa: Critical Review
- Asoba, Samson Nambei, Patricia, Nteboheng Mefi
- Authors: Asoba, Samson Nambei , Patricia, Nteboheng Mefi
- Date: 2021
- Subjects: Educational Leadership Education (Higher) College department heads Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/8082 , vital:61392 , xlink:href="https://www.abacademies.org/articles/leadership-styles-and-employee-job-satisfaction-a-case-of-head-of-departments-in-walter-sisulu-university-10942.html"
- Description: This study was based on the relationship between the leadership styles of Academic head of Department and employee job satisfaction at the Higher Education Institution (HEI). In so doing, the study was based on the following questions: What is the relationship between leadership styles of HODs and employee job satisfaction in a Higher Education institution in the Eastern Cape Province of South Africa. A purposive sampling technique was utilised to select the participants, which comprised 80 academic staff members to which the researcher hand-delivered 80 questionnaires. The study employed a quantitative method to collect and analyse data. The study found that Perceptions on the leadership styles of academic HODs at the HEI are varied. No clear pattern emerged on what leadership styles are prevalent. The relationship between leadership styles and employee job satisfaction appears to be nonlinear. Job satisfaction is a phenomenon that is determined by many factors, not simply leadership styles.
- Full Text:
- Date Issued: 2021
- Authors: Asoba, Samson Nambei , Patricia, Nteboheng Mefi
- Date: 2021
- Subjects: Educational Leadership Education (Higher) College department heads Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/8082 , vital:61392 , xlink:href="https://www.abacademies.org/articles/leadership-styles-and-employee-job-satisfaction-a-case-of-head-of-departments-in-walter-sisulu-university-10942.html"
- Description: This study was based on the relationship between the leadership styles of Academic head of Department and employee job satisfaction at the Higher Education Institution (HEI). In so doing, the study was based on the following questions: What is the relationship between leadership styles of HODs and employee job satisfaction in a Higher Education institution in the Eastern Cape Province of South Africa. A purposive sampling technique was utilised to select the participants, which comprised 80 academic staff members to which the researcher hand-delivered 80 questionnaires. The study employed a quantitative method to collect and analyse data. The study found that Perceptions on the leadership styles of academic HODs at the HEI are varied. No clear pattern emerged on what leadership styles are prevalent. The relationship between leadership styles and employee job satisfaction appears to be nonlinear. Job satisfaction is a phenomenon that is determined by many factors, not simply leadership styles.
- Full Text:
- Date Issued: 2021
The Dassie and the Hunter: A South African Meeting
- Authors: Kaschula, Russell H
- Date: 2005
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/175147 , vital:42547 , https://doi.org/10.4314/tvl.v43i1.29727
- Description: This book does not resemble any of Jeff Opland’s previous academic works. There is no similarity in style, and to some extent content. His previous books, namely, Xhosa oral poetry: Aspects of a black South African tradition (Cambridge University Press, 1983), and Xhosa poets and poetry (David Philip, 1998), were written as purely scientific, academic works. The Dassie and the Hunter amounts to a subtle snub of academia and its restrictive rules. Though written by Opland, it is as if he and his research subject, Manisi, have colluded to make this work different and special, in a personal mystical way, disregarding academic etiquette, weaving a more creative, poetic tapestry. This makes the book an interesting read. In style and content, it is neither rigorously academic, solely biographical, nor purely creative. It evades classification. It is individualistic.
- Full Text:
- Date Issued: 2005
- Authors: Kaschula, Russell H
- Date: 2005
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/175147 , vital:42547 , https://doi.org/10.4314/tvl.v43i1.29727
- Description: This book does not resemble any of Jeff Opland’s previous academic works. There is no similarity in style, and to some extent content. His previous books, namely, Xhosa oral poetry: Aspects of a black South African tradition (Cambridge University Press, 1983), and Xhosa poets and poetry (David Philip, 1998), were written as purely scientific, academic works. The Dassie and the Hunter amounts to a subtle snub of academia and its restrictive rules. Though written by Opland, it is as if he and his research subject, Manisi, have colluded to make this work different and special, in a personal mystical way, disregarding academic etiquette, weaving a more creative, poetic tapestry. This makes the book an interesting read. In style and content, it is neither rigorously academic, solely biographical, nor purely creative. It evades classification. It is individualistic.
- Full Text:
- Date Issued: 2005
Preference for C4 shade grasses increases hatchling performance in the butterfly, Bicyclus safitza
- Nokelainen, Ossi, Ripley, Bradford Sherman, Van Bergen, Erik, Osborne, Colin P, Brakefield, Paul M
- Authors: Nokelainen, Ossi , Ripley, Bradford Sherman , Van Bergen, Erik , Osborne, Colin P , Brakefield, Paul M
- Date: 2016
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61424 , vital:28025 , http://onlinelibrary.wiley.com/doi/10.1002/ece3.2235/full
- Description: The Miocene radiation of C4 grasses under high-temperature and low ambient CO2 levels occurred alongside the transformation of a largely forested landscape into savanna. This inevitably changed the host plant regime of herbivores, and the simultaneous diversification of many consumer lineages, including Bicyclus butterflies in Africa, suggests that the radiations of grasses and grazers may be evolutionary linked. We examined mechanisms for this plant–herbivore interaction with the grass-feeding Bicyclus safitza in South Africa. In a controlled environment, we tested oviposition preference and hatchling performance on local grasses with C3 or C4 photosynthetic pathways that grow either in open or shaded habitats. We predicted preference for C3 plants due to a hypothesized lower processing cost and higher palatability to herbivores. In contrast, we found that females preferred C4 shade grasses rather than either C4 grasses from open habitats or C3 grasses. The oviposition preference broadly followed hatchling performance, although hatchling survival was equally good on C4 or C3 shade grasses. This finding was explained by leaf toughness; shade grasses were softer than grasses from open habitats. Field monitoring revealed a preference of adults for shaded habitats, and stable isotope analysis of field-sampled individuals confirmed their preference for C4 grasses as host plants. Our findings suggest that plant–herbivore interactions can influence the direction of selection in a grass-feeding butterfly. Based on this work, we postulate future research to test whether these interactions more generally contribute to radiations in herbivorous insects via expansions into new, unexploited ecological niches.
- Full Text:
- Date Issued: 2016
- Authors: Nokelainen, Ossi , Ripley, Bradford Sherman , Van Bergen, Erik , Osborne, Colin P , Brakefield, Paul M
- Date: 2016
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61424 , vital:28025 , http://onlinelibrary.wiley.com/doi/10.1002/ece3.2235/full
- Description: The Miocene radiation of C4 grasses under high-temperature and low ambient CO2 levels occurred alongside the transformation of a largely forested landscape into savanna. This inevitably changed the host plant regime of herbivores, and the simultaneous diversification of many consumer lineages, including Bicyclus butterflies in Africa, suggests that the radiations of grasses and grazers may be evolutionary linked. We examined mechanisms for this plant–herbivore interaction with the grass-feeding Bicyclus safitza in South Africa. In a controlled environment, we tested oviposition preference and hatchling performance on local grasses with C3 or C4 photosynthetic pathways that grow either in open or shaded habitats. We predicted preference for C3 plants due to a hypothesized lower processing cost and higher palatability to herbivores. In contrast, we found that females preferred C4 shade grasses rather than either C4 grasses from open habitats or C3 grasses. The oviposition preference broadly followed hatchling performance, although hatchling survival was equally good on C4 or C3 shade grasses. This finding was explained by leaf toughness; shade grasses were softer than grasses from open habitats. Field monitoring revealed a preference of adults for shaded habitats, and stable isotope analysis of field-sampled individuals confirmed their preference for C4 grasses as host plants. Our findings suggest that plant–herbivore interactions can influence the direction of selection in a grass-feeding butterfly. Based on this work, we postulate future research to test whether these interactions more generally contribute to radiations in herbivorous insects via expansions into new, unexploited ecological niches.
- Full Text:
- Date Issued: 2016
Zinc (II) 2, 9, 16, 23-tetrakis [4-(N-methylpyridyloxy)]-phthalocyanine anchored on an electrospun polysulfone polymer fiber: Application for photosensitized conversion of methyl orange
- Zugle, Ruphino, Nyokong, Tebello
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232741 , vital:50020 , xlink:href="https://doi.org/10.1016/j.molcata.2012.10.001"
- Description: In this work, a comparative study of photodegradation of methyl orange, an azo dye, in homogeneous aqueous solution of a quarternized cationic zinc phthalocyanine and a heterogeneous catalytic system based on the same phthalocyanine anchored on polysulfone polymer fiber is presented. In both cases, conversion involved the azo bond of the dye with no detectable opening up of the aromatic benzene rings. The reaction kinetics in both cases were consistent with first order with the conversion occurring in the homogeneous system being faster than when the functionalized polymer fiber was used. The reaction products consisted of a coupling product as well as a series of oligopolymeric products.
- Full Text:
- Date Issued: 2013
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232741 , vital:50020 , xlink:href="https://doi.org/10.1016/j.molcata.2012.10.001"
- Description: In this work, a comparative study of photodegradation of methyl orange, an azo dye, in homogeneous aqueous solution of a quarternized cationic zinc phthalocyanine and a heterogeneous catalytic system based on the same phthalocyanine anchored on polysulfone polymer fiber is presented. In both cases, conversion involved the azo bond of the dye with no detectable opening up of the aromatic benzene rings. The reaction kinetics in both cases were consistent with first order with the conversion occurring in the homogeneous system being faster than when the functionalized polymer fiber was used. The reaction products consisted of a coupling product as well as a series of oligopolymeric products.
- Full Text:
- Date Issued: 2013
External Factors affecting Blackboard Learning Management System adoption by Students: Evidence from a Historically Disadvantaged Higher Education Institution in South Africa
- O. Matarirano, M. Panicker, N.R. Jere https://orcid.org/0000-0001-8966-2753, A. Maliwa
- Authors: O. Matarirano , M. Panicker , N.R. Jere https://orcid.org/0000-0001-8966-2753 , A. Maliwa
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3304 , vital:43306 , https://doi.org/10.20853/35-2-4025
- Description: Learning Management Systems (LMS) have the ability to transform learning experiences of students in Higher Education Institutions (HEI). In addition to the developmental benefits, LMS assist teaching and learning during student unrests, a common feature in historically disadvantaged institutions in South Africa. Regardless of the benefits of LMS platforms such as Blackboard, the utilisation by university students at the institution under study has been very low. Applying cross sectional electronic survey, this study identifies the key factors influencing technology adoption, as identified in the General Extended Technology Acceptance Model for E-Learning (GETAMEL), behind perceived ease of use and perceived usefulness in the adoption of technology. A sample of 125 students at a historically disadvantaged institution in South Africa was considered for the study. Data was collected to understand their perceptions on use of Blackboard Learning Management System (BB) for learning. Data was analysed with SmartPLS statistical analysis software. Results show that perceived ease of use of BB is influenced by computer self-efficacy, computer amusement and computer anxiety whilst perceived usefulness of BB is influenced by subjective norm and computer enjoyment. The findings also show computer experience to significantly affect computer self-efficacy and computer self-efficacy to affect computer enjoyment. The article presents the external factors that affect the usage of LMS at one of the historically disadvantaged HEI in South Africa. HEI leadership has to prioritise the identified external factors to increase chances of acceptance and utilisation of Blackboard by learners.
- Full Text:
- Date Issued: 2021
- Authors: O. Matarirano , M. Panicker , N.R. Jere https://orcid.org/0000-0001-8966-2753 , A. Maliwa
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3304 , vital:43306 , https://doi.org/10.20853/35-2-4025
- Description: Learning Management Systems (LMS) have the ability to transform learning experiences of students in Higher Education Institutions (HEI). In addition to the developmental benefits, LMS assist teaching and learning during student unrests, a common feature in historically disadvantaged institutions in South Africa. Regardless of the benefits of LMS platforms such as Blackboard, the utilisation by university students at the institution under study has been very low. Applying cross sectional electronic survey, this study identifies the key factors influencing technology adoption, as identified in the General Extended Technology Acceptance Model for E-Learning (GETAMEL), behind perceived ease of use and perceived usefulness in the adoption of technology. A sample of 125 students at a historically disadvantaged institution in South Africa was considered for the study. Data was collected to understand their perceptions on use of Blackboard Learning Management System (BB) for learning. Data was analysed with SmartPLS statistical analysis software. Results show that perceived ease of use of BB is influenced by computer self-efficacy, computer amusement and computer anxiety whilst perceived usefulness of BB is influenced by subjective norm and computer enjoyment. The findings also show computer experience to significantly affect computer self-efficacy and computer self-efficacy to affect computer enjoyment. The article presents the external factors that affect the usage of LMS at one of the historically disadvantaged HEI in South Africa. HEI leadership has to prioritise the identified external factors to increase chances of acceptance and utilisation of Blackboard by learners.
- Full Text:
- Date Issued: 2021
PKS 2250−351: A Giant Radio Galaxy in Abell 3936
- Seymour, N, Huynh, M, Shabala, S S, Rogers, J, Davies, L J M, Turner, R J, O'Brien, A, Ishwara-Chandra, C H, Thorne, J E, Galvin, T J, Jarrett, T, Anderbach, H, Anderson, A, Bunton, J, Chow, K, Collier, J D, Driver, S, Filipovic, M D, Gurkan, G, Hopkins, A M, Kapinska, A D, Leahy, D A, Marvil, J, Manojlovic, P, Norris, R P, Phillips, C, Robotham, A, Rudnick, L, Singh, V, White, S V
- Authors: Seymour, N , Huynh, M , Shabala, S S , Rogers, J , Davies, L J M , Turner, R J , O'Brien, A , Ishwara-Chandra, C H , Thorne, J E , Galvin, T J , Jarrett, T , Anderbach, H , Anderson, A , Bunton, J , Chow, K , Collier, J D , Driver, S , Filipovic, M D , Gurkan, G , Hopkins, A M , Kapinska, A D , Leahy, D A , Marvil, J , Manojlovic, P , Norris, R P , Phillips, C , Robotham, A , Rudnick, L , Singh, V , White, S V
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150320 , vital:38967 , https://doi.org/10.1017/pasa.2019.49
- Description: We present a detailed analysis of the radio galaxy PKS , a giant of 1.2 Mpc projected size, its host galaxy, and its environment. We use radio data from the Murchison Widefield Array, the upgraded Giant Metre-wavelength Radio Telescope, the Australian Square Kilometre Array Pathfinder, and the Australia Telescope Compact Array to model the jet power and age. Optical and IR data come from the Galaxy And Mass Assembly (GAMA) survey and provide information on the host galaxy and environment.
- Full Text:
- Date Issued: 2020
- Authors: Seymour, N , Huynh, M , Shabala, S S , Rogers, J , Davies, L J M , Turner, R J , O'Brien, A , Ishwara-Chandra, C H , Thorne, J E , Galvin, T J , Jarrett, T , Anderbach, H , Anderson, A , Bunton, J , Chow, K , Collier, J D , Driver, S , Filipovic, M D , Gurkan, G , Hopkins, A M , Kapinska, A D , Leahy, D A , Marvil, J , Manojlovic, P , Norris, R P , Phillips, C , Robotham, A , Rudnick, L , Singh, V , White, S V
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150320 , vital:38967 , https://doi.org/10.1017/pasa.2019.49
- Description: We present a detailed analysis of the radio galaxy PKS , a giant of 1.2 Mpc projected size, its host galaxy, and its environment. We use radio data from the Murchison Widefield Array, the upgraded Giant Metre-wavelength Radio Telescope, the Australian Square Kilometre Array Pathfinder, and the Australia Telescope Compact Array to model the jet power and age. Optical and IR data come from the Galaxy And Mass Assembly (GAMA) survey and provide information on the host galaxy and environment.
- Full Text:
- Date Issued: 2020
Effects of symmetry and the number of positive charges on the photocatalytic activity of indium phthalocyanines when embedded in electrospun fibers
- Chakona, Gamuchirai, Nyokong, Tebello
- Authors: Chakona, Gamuchirai , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188304 , vital:44743 , xlink:href="https://doi.org/10.1016/j.ica.2016.12.025"
- Description: Photooxidations of bisphenol A and 4-chlorophenol were carried out in this study using two asymmetric indium(III) phthalocyanines photosensitizers: the first consisting of one quaternized 4-pyridyloxyl and no other substituents (complex 1) and the second containing three quaternized 4-pyridylsulfanyl units and one aminophenoxy (complex 3). The asymmetry of complex 3 is additionally caused by the presence of two linking atoms (O and S). The symmetrically substituted indium(III) phthalocyanine containing four quaternized 4-pyridyloxyl units (complex 2) was also studied. The complexes were embedded in electrospun polystyrene fiber for heterogeneous photocatalytic transformation of 4-chlorophenol and bisphenol A. When immobilized on electrospun fibers, complexes 1, 2 and 3 gave singlet oxygen values of 0.31, 0.39 and 0.50 in water, respectively. Complex 3 showed the best photocatalytic behavior with observed rate constants of 2.8 × 10−3 min−1 for bisphenol A and 3.8 × 10−3 min−1 for 4-chlorophenol.
- Full Text:
- Date Issued: 2017
- Authors: Chakona, Gamuchirai , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188304 , vital:44743 , xlink:href="https://doi.org/10.1016/j.ica.2016.12.025"
- Description: Photooxidations of bisphenol A and 4-chlorophenol were carried out in this study using two asymmetric indium(III) phthalocyanines photosensitizers: the first consisting of one quaternized 4-pyridyloxyl and no other substituents (complex 1) and the second containing three quaternized 4-pyridylsulfanyl units and one aminophenoxy (complex 3). The asymmetry of complex 3 is additionally caused by the presence of two linking atoms (O and S). The symmetrically substituted indium(III) phthalocyanine containing four quaternized 4-pyridyloxyl units (complex 2) was also studied. The complexes were embedded in electrospun polystyrene fiber for heterogeneous photocatalytic transformation of 4-chlorophenol and bisphenol A. When immobilized on electrospun fibers, complexes 1, 2 and 3 gave singlet oxygen values of 0.31, 0.39 and 0.50 in water, respectively. Complex 3 showed the best photocatalytic behavior with observed rate constants of 2.8 × 10−3 min−1 for bisphenol A and 3.8 × 10−3 min−1 for 4-chlorophenol.
- Full Text:
- Date Issued: 2017
Water-soluble quaternized mercaptopyridine-substituted zinc-phthalocyanines
- Durmuş, Mahmut, Yaman, Hanif, Göl, Cem, Ahsen, Vefa, Nyokong, Tebello
- Authors: Durmuş, Mahmut , Yaman, Hanif , Göl, Cem , Ahsen, Vefa , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247133 , vital:51549 , xlink:href="https://doi.org/10.1016/j.dyepig.2011.02.007"
- Description: The synthesis and characterization of the new zinc phthalocyanine derivatives, tetra- (non-peripheral, 5) and octa-(peripheral, 6) substituted with 2-mercaptopyridine and their respective quaternized derivatives (8 and 9) are reported. Photochemical and photophysical properties of the new complexes are compared with those of the previously reported peripherally tetra-substituted complexes 7 and 10. The quaternized compounds exhibit excellent solubility in water, making them potential photosensitizers for use in photodynamic therapy (PDT) of cancer. Spectroscopic, aggregation, photophysical and photochemical properties of these complexes are also investigated and compared. Photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen and photodegradation quantum yield) properties of these phthalocyanine photosensitizers are very important for the assessment of these complexes as PDT agents. In this study, the effects of the position of the substituents and quaternization of the substituents on the photophysical and photochemical parameters of the zinc phthalocyanines are also reported. This study also showed that the water-soluble quaternized zinc phthalocyanines strongly bind to blood plasma proteins such as bovine serum albumin (BSA).
- Full Text:
- Date Issued: 2011
- Authors: Durmuş, Mahmut , Yaman, Hanif , Göl, Cem , Ahsen, Vefa , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247133 , vital:51549 , xlink:href="https://doi.org/10.1016/j.dyepig.2011.02.007"
- Description: The synthesis and characterization of the new zinc phthalocyanine derivatives, tetra- (non-peripheral, 5) and octa-(peripheral, 6) substituted with 2-mercaptopyridine and their respective quaternized derivatives (8 and 9) are reported. Photochemical and photophysical properties of the new complexes are compared with those of the previously reported peripherally tetra-substituted complexes 7 and 10. The quaternized compounds exhibit excellent solubility in water, making them potential photosensitizers for use in photodynamic therapy (PDT) of cancer. Spectroscopic, aggregation, photophysical and photochemical properties of these complexes are also investigated and compared. Photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen and photodegradation quantum yield) properties of these phthalocyanine photosensitizers are very important for the assessment of these complexes as PDT agents. In this study, the effects of the position of the substituents and quaternization of the substituents on the photophysical and photochemical parameters of the zinc phthalocyanines are also reported. This study also showed that the water-soluble quaternized zinc phthalocyanines strongly bind to blood plasma proteins such as bovine serum albumin (BSA).
- Full Text:
- Date Issued: 2011
Pushing against ‘China-Africa’ slowly, and with small stories:
- Authors: Simbao, Ruth K
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146778 , vital:38556 , http://www.somethingweafricansgot.com/about-1
- Description: the new focus on african arts and critical thought.
- Full Text:
- Date Issued: 2019
- Authors: Simbao, Ruth K
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146778 , vital:38556 , http://www.somethingweafricansgot.com/about-1
- Description: the new focus on african arts and critical thought.
- Full Text:
- Date Issued: 2019
Factors influencing the shape of CW-OSL signal obtained by stimulation of very deep traps in carbon-doped aluminium oxide: an experimental study
- Nyirenda, Angel N, Chithambo, Makaiko L
- Authors: Nyirenda, Angel N , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115493 , vital:34149 , https://doi.org/10.1016/j.jlumin.2017.07.016
- Description: The optically stimulated luminescence from carbon-doped aluminium oxide (α-Al2O3:C) displays a peak with time under certain measurement conditions. In this paper, we present factors that influence the peak-like shape of continuous-wave optically stimulated luminescence (CW-OSL) signal. The report is based on the experimental study of OSL signals obtained by stimulation of very deep traps in α-Al2O3:C. Methods exploiting post-irradiation annealing, variable dose and temperature dependent OSL measurements were used in the investigation. It is found that the rising part of the CW-OSL peak is obtained when the rate of retrapping at the most optically active trap (main trap) exceeds the rate of direct radiative recombination following optical release of charges from all optically active traps. This is possible if, during optical stimulation, the primary trap responsible for OSL i.e. the main trap, is substantially unoccupied and the very deep, donor traps are substantially filled up. The rate of charge retrapping itself is deduced to depend on the occupancy of the acceptor traps i.e. shallow, main and secondary traps; concentration of charge carriers in the very deep, donor traps; the post-irradiation annealing temperature and the temperature at which the OSL is measured.
- Full Text: false
- Date Issued: 2017
- Authors: Nyirenda, Angel N , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115493 , vital:34149 , https://doi.org/10.1016/j.jlumin.2017.07.016
- Description: The optically stimulated luminescence from carbon-doped aluminium oxide (α-Al2O3:C) displays a peak with time under certain measurement conditions. In this paper, we present factors that influence the peak-like shape of continuous-wave optically stimulated luminescence (CW-OSL) signal. The report is based on the experimental study of OSL signals obtained by stimulation of very deep traps in α-Al2O3:C. Methods exploiting post-irradiation annealing, variable dose and temperature dependent OSL measurements were used in the investigation. It is found that the rising part of the CW-OSL peak is obtained when the rate of retrapping at the most optically active trap (main trap) exceeds the rate of direct radiative recombination following optical release of charges from all optically active traps. This is possible if, during optical stimulation, the primary trap responsible for OSL i.e. the main trap, is substantially unoccupied and the very deep, donor traps are substantially filled up. The rate of charge retrapping itself is deduced to depend on the occupancy of the acceptor traps i.e. shallow, main and secondary traps; concentration of charge carriers in the very deep, donor traps; the post-irradiation annealing temperature and the temperature at which the OSL is measured.
- Full Text: false
- Date Issued: 2017
Electrocatalytic activity of Schiff base containing copper phthalocyanines towards the detection of catechol
- Ndebele, Nobuhle, Sen, Pinar, Nyokong, Tebello
- Authors: Ndebele, Nobuhle , Sen, Pinar , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231410 , vital:49885 , xlink:href="https://doi.org/10.1016/j.poly.2021.115518"
- Description: In this study, four new copper phthalocyanine complexes were synthesised and studied as electrocatalysts for the detection of catechol. Two of these complexes were derived from a symmetrical benzaldehyde phthalocyanine complex via the condensation of the benzaldehyde substituents with amine reagents. The electrocatalysts proved to be highly stable towards the detection of catechol. The oxidation peaks obtained using cyclic voltammetry range from 0.20 to 0.38 V. Detection limits were obtained via chronoamperometry and are as low as 0.16 µM with fairly high sensitives being obtained. Overall all four copper complexes exhibited excellent electrocatalytic activity towards the electrooxidation of catechol.
- Full Text:
- Date Issued: 2021
- Authors: Ndebele, Nobuhle , Sen, Pinar , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231410 , vital:49885 , xlink:href="https://doi.org/10.1016/j.poly.2021.115518"
- Description: In this study, four new copper phthalocyanine complexes were synthesised and studied as electrocatalysts for the detection of catechol. Two of these complexes were derived from a symmetrical benzaldehyde phthalocyanine complex via the condensation of the benzaldehyde substituents with amine reagents. The electrocatalysts proved to be highly stable towards the detection of catechol. The oxidation peaks obtained using cyclic voltammetry range from 0.20 to 0.38 V. Detection limits were obtained via chronoamperometry and are as low as 0.16 µM with fairly high sensitives being obtained. Overall all four copper complexes exhibited excellent electrocatalytic activity towards the electrooxidation of catechol.
- Full Text:
- Date Issued: 2021
Cross-sectional study of prevalence and determinants of uncontrolled hypertension among South African adult residents of Mkhondo municipality
- Masilela, Charity, Pearce, Brendon, Ongole, Joven Jebio, Adeniyi, Oladele Vincent, Benjeddou, Mongi
- Authors: Masilela, Charity , Pearce, Brendon , Ongole, Joven Jebio , Adeniyi, Oladele Vincent , Benjeddou, Mongi
- Date: 2020
- Subjects: Blood pressure control , Dyslipidaemia , Uncontrolled hypertension
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/11260/4481 , vital:44124 , https://doi.org/10.1186/s12889-020-09174-7
- Description: Achieving the blood pressure treatment target in individuals with hypertension is a serious global health challenge. Furthermore, the actual burden of uncontrolled hypertension is poorly understood, especially in the developing countries. Therefore, this study comprehensively examined the prevalence and factors associated with uncontrolled hypertension in individuals receiving care at the primary healthcare facilities in the rural areas of Mkhondo Municipality in the Mpumalanga Province, South Africa. Methods: In this cross-sectional study, 329 individuals attending care for hypertension were recruited from January 2019 to June 2019 at three primary healthcare centres, namely, Piet Retief hospital, Mkhondo town clinic and Thandukukhanya community health centre. Uncontrolled hypertension was defined as systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg in accordance with the South African Hypertension Society guideline (2014). Multiple logistic regression (Forward LR method) analysis was used to identify the significant determinants of uncontrolled hypertension. Results: The majority of the participants were 55 years old and above (69.0%), Zulus (81.2%), non-smokers (84.19%) and had been diagnosed with hypertension for more than a year prior to the study (72.64%). The overall prevalence of uncontrolled hypertension was 56.83% (n = 187) with no significant difference between sexes, 57.38% male versus 56.88% female, respectively. In the multiple logistic regression model analysis after adjusting for confounding variables, obesity (AOR = 2.90; 95% CI 1.66–5.05), physical activity (AOR = 4.79; 95% CI 2.15–10.65) and HDL-C (AOR = 5.66; 95% CI 3.33–9.60) were the significant and independent determinants of uncontrolled hypertension in the cohort. Conclusion: The high prevalence of uncontrolled hypertension in the study setting can be largely attributed to obesity, physical activity and dyslipidaemia. Treatment will require the collaborative efforts of individuals, clinicians and health authorities. All these determinants should be addressed decisively so as to achieve the treatment blood pressure targets in the study population.
- Full Text:
- Date Issued: 2020
- Authors: Masilela, Charity , Pearce, Brendon , Ongole, Joven Jebio , Adeniyi, Oladele Vincent , Benjeddou, Mongi
- Date: 2020
- Subjects: Blood pressure control , Dyslipidaemia , Uncontrolled hypertension
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/11260/4481 , vital:44124 , https://doi.org/10.1186/s12889-020-09174-7
- Description: Achieving the blood pressure treatment target in individuals with hypertension is a serious global health challenge. Furthermore, the actual burden of uncontrolled hypertension is poorly understood, especially in the developing countries. Therefore, this study comprehensively examined the prevalence and factors associated with uncontrolled hypertension in individuals receiving care at the primary healthcare facilities in the rural areas of Mkhondo Municipality in the Mpumalanga Province, South Africa. Methods: In this cross-sectional study, 329 individuals attending care for hypertension were recruited from January 2019 to June 2019 at three primary healthcare centres, namely, Piet Retief hospital, Mkhondo town clinic and Thandukukhanya community health centre. Uncontrolled hypertension was defined as systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg in accordance with the South African Hypertension Society guideline (2014). Multiple logistic regression (Forward LR method) analysis was used to identify the significant determinants of uncontrolled hypertension. Results: The majority of the participants were 55 years old and above (69.0%), Zulus (81.2%), non-smokers (84.19%) and had been diagnosed with hypertension for more than a year prior to the study (72.64%). The overall prevalence of uncontrolled hypertension was 56.83% (n = 187) with no significant difference between sexes, 57.38% male versus 56.88% female, respectively. In the multiple logistic regression model analysis after adjusting for confounding variables, obesity (AOR = 2.90; 95% CI 1.66–5.05), physical activity (AOR = 4.79; 95% CI 2.15–10.65) and HDL-C (AOR = 5.66; 95% CI 3.33–9.60) were the significant and independent determinants of uncontrolled hypertension in the cohort. Conclusion: The high prevalence of uncontrolled hypertension in the study setting can be largely attributed to obesity, physical activity and dyslipidaemia. Treatment will require the collaborative efforts of individuals, clinicians and health authorities. All these determinants should be addressed decisively so as to achieve the treatment blood pressure targets in the study population.
- Full Text:
- Date Issued: 2020
Syntheses and photochemical properties of octasubstituted phthalocyaninato zinc complexes
- Maree, Suzanne, Nyokong, Tebello
- Authors: Maree, Suzanne , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304841 , vital:58495 , xlink:href="https://doi.org/10.1002/jpp.388"
- Description: In this work a selection of octasubstituted phthalocyaninato zinc complexes were synthesized and their photochemistry studied. The substituents included cholesterol (3a), estrone (3b), naphthol (3c) and phenoxy groups substituted with CH3 (3d), C(CH3)3 (at two positions, 3e), C(CH3)3 (3f), NO2 (3g), NH2 (3h), COH (3i), COOH (3j), and H (3k). In general, complexes containing electron-donating groups attached to the phenoxy ring (e.g. 3e and 3f) were found to be photochemically unstable with photobleaching quantum yields of the order of 10−3. In the presence of electron-withdrawing groups (3g, 3i, and 3j) the photobleaching quantum yields were of the order of 10−6 to 10−5. Singlet oxygen quantum yields (ΦΔ) ranged from 0.01 to 0.73. The lowest ΦΔ was observed for the highly aggregated complex 3c. All the complexes showed aggregation at high concentrations. Electrochemical reduction using a thin-layer spectroelectrochemistry cell showed that the complexes become more monomeric following reduction.
- Full Text:
- Date Issued: 2001
- Authors: Maree, Suzanne , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304841 , vital:58495 , xlink:href="https://doi.org/10.1002/jpp.388"
- Description: In this work a selection of octasubstituted phthalocyaninato zinc complexes were synthesized and their photochemistry studied. The substituents included cholesterol (3a), estrone (3b), naphthol (3c) and phenoxy groups substituted with CH3 (3d), C(CH3)3 (at two positions, 3e), C(CH3)3 (3f), NO2 (3g), NH2 (3h), COH (3i), COOH (3j), and H (3k). In general, complexes containing electron-donating groups attached to the phenoxy ring (e.g. 3e and 3f) were found to be photochemically unstable with photobleaching quantum yields of the order of 10−3. In the presence of electron-withdrawing groups (3g, 3i, and 3j) the photobleaching quantum yields were of the order of 10−6 to 10−5. Singlet oxygen quantum yields (ΦΔ) ranged from 0.01 to 0.73. The lowest ΦΔ was observed for the highly aggregated complex 3c. All the complexes showed aggregation at high concentrations. Electrochemical reduction using a thin-layer spectroelectrochemistry cell showed that the complexes become more monomeric following reduction.
- Full Text:
- Date Issued: 2001
Interaction of graphene quantum dots with 4-acetamido-2, 2, 6, 6-tetramethylpiperidine-oxyl free radicals
- Achadu, Ojodomo John, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189031 , vital:44810 , xlink:href="https://doi.org/10.1007/s10895-015-1712-0"
- Description: We report on the interaction of graphene quantum dots (GQDs) with 4-acetamido-2,2,6,6-tetramethylpiperidineoxyl (4-acetamido-TEMPO) free radicals. The GQDs were N and S, N doped. The fluorescence quantum yields were higher for the doped GQDs compared to the undoped. The interaction is assessed by spectrofluorimetric, steady state/time resolved fluorescence and electron paramagnetic resonance (EPR) techniques. Fluorescence quenching was observed upon the addition of 4-acetamido-TEMPO to the GQDs. Photoinduced electron transfer (PET) mechanism was suggested as the plausible mechanism involved in the fluorescence quenching in which 4-acetamido-TEMPO acted as the electron acceptor.
- Full Text:
- Date Issued: 2016
- Authors: Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189031 , vital:44810 , xlink:href="https://doi.org/10.1007/s10895-015-1712-0"
- Description: We report on the interaction of graphene quantum dots (GQDs) with 4-acetamido-2,2,6,6-tetramethylpiperidineoxyl (4-acetamido-TEMPO) free radicals. The GQDs were N and S, N doped. The fluorescence quantum yields were higher for the doped GQDs compared to the undoped. The interaction is assessed by spectrofluorimetric, steady state/time resolved fluorescence and electron paramagnetic resonance (EPR) techniques. Fluorescence quenching was observed upon the addition of 4-acetamido-TEMPO to the GQDs. Photoinduced electron transfer (PET) mechanism was suggested as the plausible mechanism involved in the fluorescence quenching in which 4-acetamido-TEMPO acted as the electron acceptor.
- Full Text:
- Date Issued: 2016
A hand to mouth existence: hurdles emanating from the COVID 19 Pandemic for Women Survivalist Entrepreneurs in Johannesburg, South Africa
- Mapuranga, Miston, Maziriri, Eugine Tafadzwa, Rukuni, Tarisai Fritz
- Authors: Mapuranga, Miston , Maziriri, Eugine Tafadzwa , Rukuni, Tarisai Fritz
- Date: 2021-09-13
- Subjects: Covid-19 (Disease) , Women-owned business enterprises , Entrepreneurship
- Language: English
- Type: article
- Identifier: http://hdl.handle.net/11260/7460 , vital:53960 , https://doi.org/10.31920/2634-3622/2021/v10n3a6
- Description: There are many women survivalist entrepreneurs in South Africa, many of whom work in the informal sector. The emergence of theCOVID-19 pandemic has a devastating effect on their entrepreneurial projects. While both the public and private sectors have initiated various measures to ease the blow, obstacles continue to confront them. This study sought to examine the challenges faced by women survivalist entrepreneurs in South Africa’s Johannesburg metropolitan area. The researchers gathered qualitative data using a qualitative research approach by conducting semi-structured face-to-face interviews. The data was analysed using thematic analyses. The themes that emerged from the findings include; a lack of capital for reinvestment, no government grant support, a decline in the demand for products by the market, rotting agricultural produce or stock, a battle for strategic selling points and numerous confrontations with police as a result of not meeting the regulatory rules relating to COVID-19. The present research provides theoretical implications for academics in entrepreneurship by enhancing the understanding of the hurdles that these entrepreneurs have experienced because of COVID-19. On the practitioners’ side, this work offers avenues for women survivalist entrepreneurs to improve their entrepreneurial ventures and eventually eliminate the challenges they face when running their ventures. This study also offers policy implications. For example, existing government policies can be amended to make the working conditions of women survivalist entrepreneurs better or make the rules under which they operate simpler. This study contributes to entrepreneurship literature by uncovering the difficulties faced by women survivalist entrepreneurs due to the COVID-19 pandemic. It will assist other scholars in further developing this research field. As such, this research is important for women survivalist entrepreneurs because most of them endeavour to enhance entrepreneurial performance for the betterment of their lives. Governments may also use the study to develop interventions aimed at facilitating the growth and development of women survivalist entrepreneurs.
- Full Text:
- Date Issued: 2021-09-13
- Authors: Mapuranga, Miston , Maziriri, Eugine Tafadzwa , Rukuni, Tarisai Fritz
- Date: 2021-09-13
- Subjects: Covid-19 (Disease) , Women-owned business enterprises , Entrepreneurship
- Language: English
- Type: article
- Identifier: http://hdl.handle.net/11260/7460 , vital:53960 , https://doi.org/10.31920/2634-3622/2021/v10n3a6
- Description: There are many women survivalist entrepreneurs in South Africa, many of whom work in the informal sector. The emergence of theCOVID-19 pandemic has a devastating effect on their entrepreneurial projects. While both the public and private sectors have initiated various measures to ease the blow, obstacles continue to confront them. This study sought to examine the challenges faced by women survivalist entrepreneurs in South Africa’s Johannesburg metropolitan area. The researchers gathered qualitative data using a qualitative research approach by conducting semi-structured face-to-face interviews. The data was analysed using thematic analyses. The themes that emerged from the findings include; a lack of capital for reinvestment, no government grant support, a decline in the demand for products by the market, rotting agricultural produce or stock, a battle for strategic selling points and numerous confrontations with police as a result of not meeting the regulatory rules relating to COVID-19. The present research provides theoretical implications for academics in entrepreneurship by enhancing the understanding of the hurdles that these entrepreneurs have experienced because of COVID-19. On the practitioners’ side, this work offers avenues for women survivalist entrepreneurs to improve their entrepreneurial ventures and eventually eliminate the challenges they face when running their ventures. This study also offers policy implications. For example, existing government policies can be amended to make the working conditions of women survivalist entrepreneurs better or make the rules under which they operate simpler. This study contributes to entrepreneurship literature by uncovering the difficulties faced by women survivalist entrepreneurs due to the COVID-19 pandemic. It will assist other scholars in further developing this research field. As such, this research is important for women survivalist entrepreneurs because most of them endeavour to enhance entrepreneurial performance for the betterment of their lives. Governments may also use the study to develop interventions aimed at facilitating the growth and development of women survivalist entrepreneurs.
- Full Text:
- Date Issued: 2021-09-13
pH study of the electrocatalytic SO2 detection at a glassy carbon electrode modified with iron (II) tetrasulfophthalocyanine
- Thamae, Mamothibe, Westbroek, Philippe, Nyokong, Tebello
- Authors: Thamae, Mamothibe , Westbroek, Philippe , Nyokong, Tebello
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304786 , vital:58490 , xlink:href="https://doi.org/10.1007/s00604-002-0914-8"
- Description: The electrocatalytic determination of SO2 is studied as a function of pH at a glassy carbon electrode modified with iron(II)tetrasulfophthalocyanine ([Fe(II)TSPc]4−). It was found in the literature that depending on pH, SO2·xH2O, HSO3 − and/or SO3 2− are the main compounds in solution, that these compounds behave differently at the electrode surface, and that the condition of the electrode surface is stable over the entire pH-range. The use of SO2(g) or sodium sulfite as starting material did result in identical curves except in the pH range from 7.5–9.0. A possible explanation could be given by proposing that SO2·xH2O is very unstable in the presence of SO3 2−. In strongly acidic medium, SO2·xH2O is the main compound, which can be oxidized as well as reduced with exchange of two electrons. HSO3 − is the main compound at pH = 4 and can also be oxidized and reduced with exchange of, respectively, two and four electrons. In alkaline solution sulfite is the main compound and can only be oxidized, also under exchange of two electrons. Detection limits are in the range of 4.0 ± 0.1 × 10−5 and 7.5 ± 0.1 × 10−5 mol L−1, dependent of pH and of the type of reaction (oxidation or reduction) used.
- Full Text:
- Date Issued: 2002
- Authors: Thamae, Mamothibe , Westbroek, Philippe , Nyokong, Tebello
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304786 , vital:58490 , xlink:href="https://doi.org/10.1007/s00604-002-0914-8"
- Description: The electrocatalytic determination of SO2 is studied as a function of pH at a glassy carbon electrode modified with iron(II)tetrasulfophthalocyanine ([Fe(II)TSPc]4−). It was found in the literature that depending on pH, SO2·xH2O, HSO3 − and/or SO3 2− are the main compounds in solution, that these compounds behave differently at the electrode surface, and that the condition of the electrode surface is stable over the entire pH-range. The use of SO2(g) or sodium sulfite as starting material did result in identical curves except in the pH range from 7.5–9.0. A possible explanation could be given by proposing that SO2·xH2O is very unstable in the presence of SO3 2−. In strongly acidic medium, SO2·xH2O is the main compound, which can be oxidized as well as reduced with exchange of two electrons. HSO3 − is the main compound at pH = 4 and can also be oxidized and reduced with exchange of, respectively, two and four electrons. In alkaline solution sulfite is the main compound and can only be oxidized, also under exchange of two electrons. Detection limits are in the range of 4.0 ± 0.1 × 10−5 and 7.5 ± 0.1 × 10−5 mol L−1, dependent of pH and of the type of reaction (oxidation or reduction) used.
- Full Text:
- Date Issued: 2002
Characterization of polymeric film of a new manganese phthalocyanine complex octa-substituted with 2-diethylaminoethanethiol, and its use for the electrochemical detection of bentazon
- Akinbulu, Isaac A, Nyokong, Tebello
- Authors: Akinbulu, Isaac A , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262568 , vital:53534 , xlink:href="https://doi.org/10.1016/j.electacta.2009.07.074"
- Description: Manganese acetate octakis-(2-diethyaminoethanethiol) phthalocyanine (AcMnODEAETPc) was newly synthesized and characterized by spectroscopic and electrochemical methods. Solution electrochemistry of the complex showed three redox processes assigned to MnIIIPc−1/MnIIIPc−2, MnIIIPc−2/MnIIPc−2 and MnIIPc−2/MnIIPc−3 species. The new molecule was polymerized onto a glassy carbon electrode (GCE) to form thin films of different thickness, giving poly-10-AcMnODEAETPc-GCE, poly-20-AcMnODEAETPc-GCE and poly-30-AcMnODEAETPc-GCE, where 10, 20 and 30 represent the number of voltammetry scans during polymerization. Three distinct redox processes were observed on the modified electrode in 0.1 M phosphate buffer solution, pH 5, which confirmed the formation of the polymer. The current signal due to the herbicide, bentazon, was dependent on film thickness; the best signal was obtained on poly-20-AcMnODEAETPc-GCE while poly-10-AcMnODEAETPc-GCE gave the least signal. However, the signals due to the herbicide were better on the different films compared to the bare electrode. Electrochemical impedance spectroscopy (EIS) technique revealed that differences in film thickness offered different charge transfer resistances, Rct, hence difference in current signals for bentazon oxidation were observed on these films. A Tafel slope of 77 mV/decade, obtained for the herbicide on poly-20-AcMnODEAETPc-GCE, denotes a fast one electron transfer followed by a slow chemical step in the electro-oxidation of bentazon. The voltammetry signals of the herbicide on the films indicated the likely involvement of ring-based redox processes in the detection of the herbicide. A plot of background corrected current response, on this film, versus the concentration of bentazon was linear within the range 50–750 μM with a detection limit of 2.48 × 10−7 M.
- Full Text:
- Date Issued: 2009
- Authors: Akinbulu, Isaac A , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262568 , vital:53534 , xlink:href="https://doi.org/10.1016/j.electacta.2009.07.074"
- Description: Manganese acetate octakis-(2-diethyaminoethanethiol) phthalocyanine (AcMnODEAETPc) was newly synthesized and characterized by spectroscopic and electrochemical methods. Solution electrochemistry of the complex showed three redox processes assigned to MnIIIPc−1/MnIIIPc−2, MnIIIPc−2/MnIIPc−2 and MnIIPc−2/MnIIPc−3 species. The new molecule was polymerized onto a glassy carbon electrode (GCE) to form thin films of different thickness, giving poly-10-AcMnODEAETPc-GCE, poly-20-AcMnODEAETPc-GCE and poly-30-AcMnODEAETPc-GCE, where 10, 20 and 30 represent the number of voltammetry scans during polymerization. Three distinct redox processes were observed on the modified electrode in 0.1 M phosphate buffer solution, pH 5, which confirmed the formation of the polymer. The current signal due to the herbicide, bentazon, was dependent on film thickness; the best signal was obtained on poly-20-AcMnODEAETPc-GCE while poly-10-AcMnODEAETPc-GCE gave the least signal. However, the signals due to the herbicide were better on the different films compared to the bare electrode. Electrochemical impedance spectroscopy (EIS) technique revealed that differences in film thickness offered different charge transfer resistances, Rct, hence difference in current signals for bentazon oxidation were observed on these films. A Tafel slope of 77 mV/decade, obtained for the herbicide on poly-20-AcMnODEAETPc-GCE, denotes a fast one electron transfer followed by a slow chemical step in the electro-oxidation of bentazon. The voltammetry signals of the herbicide on the films indicated the likely involvement of ring-based redox processes in the detection of the herbicide. A plot of background corrected current response, on this film, versus the concentration of bentazon was linear within the range 50–750 μM with a detection limit of 2.48 × 10−7 M.
- Full Text:
- Date Issued: 2009
Privacy risk and the use of Facebook Apps: a gender-focused vulnerability assessment
- van der Schyff, Karl, Flowerday, Stephen, Furnell, Steven
- Authors: van der Schyff, Karl , Flowerday, Stephen , Furnell, Steven
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149054 , vital:38800 , https://doi.org/10.1016/j.cose.2020.101866
- Description: The surveillance and subsequent privacy risks (i.e., misuse of personal information) of Facebook App data constitute a persistent problem that affects millions of users. However, despite Facebook App research on specifics such as privacy concerns, value of information, and demographics, none of them has conducted vulnerability assessments on the use of Facebook Apps as influenced by specific factors such as age, gender, and information privacy attitudes. As such, the purpose of this study was to predict the extent to which these factors influence an individual's intention to continue using Facebook Apps as part of a gender-focused vulnerability assessment. We evaluate two hypotheses by way of ordinal logistic regression using data gathered from 621 respondents. The results are indicative of the following: First, females are particularly vulnerable to privacy risks as a function of continued use of Facebook Apps. More specifically, those risks related to Facebook's access to personal information. Second, results indicate that a user's age is nonsignificant in relation to the continued use of Facebook Apps. We conclude with several theoretical and practice-oriented information privacy recommendations.
- Full Text:
- Date Issued: 2020
- Authors: van der Schyff, Karl , Flowerday, Stephen , Furnell, Steven
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149054 , vital:38800 , https://doi.org/10.1016/j.cose.2020.101866
- Description: The surveillance and subsequent privacy risks (i.e., misuse of personal information) of Facebook App data constitute a persistent problem that affects millions of users. However, despite Facebook App research on specifics such as privacy concerns, value of information, and demographics, none of them has conducted vulnerability assessments on the use of Facebook Apps as influenced by specific factors such as age, gender, and information privacy attitudes. As such, the purpose of this study was to predict the extent to which these factors influence an individual's intention to continue using Facebook Apps as part of a gender-focused vulnerability assessment. We evaluate two hypotheses by way of ordinal logistic regression using data gathered from 621 respondents. The results are indicative of the following: First, females are particularly vulnerable to privacy risks as a function of continued use of Facebook Apps. More specifically, those risks related to Facebook's access to personal information. Second, results indicate that a user's age is nonsignificant in relation to the continued use of Facebook Apps. We conclude with several theoretical and practice-oriented information privacy recommendations.
- Full Text:
- Date Issued: 2020