On-site evaluation of smoking, alcohol consumption and physical inactivity among commercial taxi drivers in Buffalo City Metropolitan Municipality, South Africa
- Adedokun, Aanuoluwa Odunayo, Ter Goon, Daniel, Owolabi, Eyitayo Omolara, Adeniyi, Oladele Vincent, Ajayi, Anthony Idowu
- Authors: Adedokun, Aanuoluwa Odunayo , Ter Goon, Daniel , Owolabi, Eyitayo Omolara , Adeniyi, Oladele Vincent , Ajayi, Anthony Idowu
- Date: 2019
- Subjects: Alcohol use , Substance use , Commercial drivers
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/11260/5086 , vital:44345 , https://doi.org/10.5539/gjhs.v11n2p110
- Description: Commercial drivers have been identified as eliciting behaviours that promote non- communicable diseases and road traffic accidents. The aim of the study is to determine the prevalence and pattern of alcohol use, smoking and physical inactivity among commercial taxi drivers in Buffalo City Metropolitan Municipality, South Africa. A cross-sectional study was conducted among 403 commercial drivers using the face-to-face interviews method. The WHO STEPwise questionnaire was used to obtain the demographic data, self-reported rate of alcohol consumption, tobacco use and physical inactivity. The participants’ mean age was 43.3 ± 12.5 years. About 30% of the participants were daily smokers, 37% consumed alcohol regularly and only 18% were physically active, whilst 82% were physically inactive. The prevalence of alcohol use, smoking and physical inactivity is high among commercial drivers in East London. Workplace health education on the health effects of these lifestyles’ risky behaviours on individuals and the general public should be given to the drivers.
- Full Text:
- Date Issued: 2019
- Authors: Adedokun, Aanuoluwa Odunayo , Ter Goon, Daniel , Owolabi, Eyitayo Omolara , Adeniyi, Oladele Vincent , Ajayi, Anthony Idowu
- Date: 2019
- Subjects: Alcohol use , Substance use , Commercial drivers
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/11260/5086 , vital:44345 , https://doi.org/10.5539/gjhs.v11n2p110
- Description: Commercial drivers have been identified as eliciting behaviours that promote non- communicable diseases and road traffic accidents. The aim of the study is to determine the prevalence and pattern of alcohol use, smoking and physical inactivity among commercial taxi drivers in Buffalo City Metropolitan Municipality, South Africa. A cross-sectional study was conducted among 403 commercial drivers using the face-to-face interviews method. The WHO STEPwise questionnaire was used to obtain the demographic data, self-reported rate of alcohol consumption, tobacco use and physical inactivity. The participants’ mean age was 43.3 ± 12.5 years. About 30% of the participants were daily smokers, 37% consumed alcohol regularly and only 18% were physically active, whilst 82% were physically inactive. The prevalence of alcohol use, smoking and physical inactivity is high among commercial drivers in East London. Workplace health education on the health effects of these lifestyles’ risky behaviours on individuals and the general public should be given to the drivers.
- 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
A comparative study of the singlet oxygen generation capability of a zinc phthalocyanine linked to graphene quantum dots through π-π stacking and covalent conjugation when embedded in asymmetric polymer membranes
- Mafukidze, Donovan M, Nyokong, Tebello
- Authors: Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187461 , vital:44655 , xlink:href="https://doi.org/10.1016/j.molstruc.2018.11.096"
- Description: Following the establishment of graphene quantum dots as potential phthalocyanine supports in photoactive membrane preparation for phthalocyanines lacking linkage functional groups, the practical efficiency of p-p stacking versus covalent linkage was investigated. Synthesized materials were characterized using FT-IR, Raman, powder X-ray diffraction, and UVeVis spectroscopies and also by transmission electron and scanning electron microscopies. Phthalocyanine loadings onto graphene quantum dots of 0.40 mg/mg and 0.14 mg/mg (Pc mass/conjugate mass) for the p-p stacked and covalent linked conjugates respectively were observed. Covalent linkage to graphene quantum dots proved to be functionally superior to p-p linkage, where singlet oxygen quantum yield value of the phthalocyanine in the membrane for the covalent linked conjugate was approximately twice that of the p-p stacked membrane.
- Full Text:
- Date Issued: 2019
- Authors: Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187461 , vital:44655 , xlink:href="https://doi.org/10.1016/j.molstruc.2018.11.096"
- Description: Following the establishment of graphene quantum dots as potential phthalocyanine supports in photoactive membrane preparation for phthalocyanines lacking linkage functional groups, the practical efficiency of p-p stacking versus covalent linkage was investigated. Synthesized materials were characterized using FT-IR, Raman, powder X-ray diffraction, and UVeVis spectroscopies and also by transmission electron and scanning electron microscopies. Phthalocyanine loadings onto graphene quantum dots of 0.40 mg/mg and 0.14 mg/mg (Pc mass/conjugate mass) for the p-p stacked and covalent linked conjugates respectively were observed. Covalent linkage to graphene quantum dots proved to be functionally superior to p-p linkage, where singlet oxygen quantum yield value of the phthalocyanine in the membrane for the covalent linked conjugate was approximately twice that of the p-p stacked membrane.
- Full Text:
- Date Issued: 2019
New type of metal-free and Zinc (II), In (III), Ga (III) phthalocyanines carrying biologically active substituents: Synthesis and photophysicochemical properties and photodynamic therapy activity
- Sen, Pinar, Managa, Muthumuni, Nyokong, Tebello
- Authors: Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186971 , vital:44552 , xlink:href="https://doi.org/10.1016/j.ica.2019.03.010"
- Description: This study reports on novel phthalocyanines having benzimidazole units which are known to have biological properties. 4-(4-(5-chloro-1H-benzo[d]imidazol-2-yl) substituted metal-free, Zn(II), In(III) and Ga(III) phthalocyanines were synthesized, these newly synthesized molecules that were substituted by oxygen bridges were fully characterized. For the purpose of determining their potency for photodynamic therapy, the photophysicochemical properties were investigated in DMSO. The H2Pc (4) showed higher fluorescence quantum yield and fluorescence lifetime as compared to metallated phthalocyanines derivatives. However, the highest singlet oxygen (ΦΔ) and triplet state quantum yields (ΦT) values were obtained with the In(III)Pc (5).
- Full Text:
- Date Issued: 2019
- Authors: Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186971 , vital:44552 , xlink:href="https://doi.org/10.1016/j.ica.2019.03.010"
- Description: This study reports on novel phthalocyanines having benzimidazole units which are known to have biological properties. 4-(4-(5-chloro-1H-benzo[d]imidazol-2-yl) substituted metal-free, Zn(II), In(III) and Ga(III) phthalocyanines were synthesized, these newly synthesized molecules that were substituted by oxygen bridges were fully characterized. For the purpose of determining their potency for photodynamic therapy, the photophysicochemical properties were investigated in DMSO. The H2Pc (4) showed higher fluorescence quantum yield and fluorescence lifetime as compared to metallated phthalocyanines derivatives. However, the highest singlet oxygen (ΦΔ) and triplet state quantum yields (ΦT) values were obtained with the In(III)Pc (5).
- Full Text:
- Date Issued: 2019
A novel axially palladium (II)-Schiff base complex substituted silicon (IV) phthalocyanine
- Sen, Pinar, Nyokong, Tebello
- Authors: Sen, Pinar , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186813 , vital:44536 , xlink:href="https://doi.org/10.1016/j.poly.2019.114135"
- Description: In this study, a novel silicon(IV) phthalocyanine is reported for the first time as a phthalocyanine derivative bearing axially a palladium(II)-Schiff base complex. The photophysical and photochemical properties of the new Si(IV)Pc, such as absorption, fluorescence, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were measured in DMSO. The new silicon phthalocyanine displayed very low fluorescence, showing efficient intersystem crossing resulting in high triplet and high singlet oxygen quantum yields in DMSO. When compared with the unsubstituted SiPcCl2, the singlet oxygen quantum yield value (UD = 0.47) in relation to the triplet quantum yield (UT = 0.82), which is an important determinant for PDT applications, increased. The photodynamic antimicrobial chemotherapy activity (PACT) of new Si(IV)Pc towards Staphylococcus aureus was determined in comparison to the unsubstituted SiPcCl2. The results of the photodynamic antimicrobial effect study demonstrated that the Pd(II) complex substituted SiPc (5) possesses excellent photodynamic activity with a reduction percentage value of 99.94% and a log red value of 3.26.
- Full Text:
- Date Issued: 2019
- Authors: Sen, Pinar , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186813 , vital:44536 , xlink:href="https://doi.org/10.1016/j.poly.2019.114135"
- Description: In this study, a novel silicon(IV) phthalocyanine is reported for the first time as a phthalocyanine derivative bearing axially a palladium(II)-Schiff base complex. The photophysical and photochemical properties of the new Si(IV)Pc, such as absorption, fluorescence, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were measured in DMSO. The new silicon phthalocyanine displayed very low fluorescence, showing efficient intersystem crossing resulting in high triplet and high singlet oxygen quantum yields in DMSO. When compared with the unsubstituted SiPcCl2, the singlet oxygen quantum yield value (UD = 0.47) in relation to the triplet quantum yield (UT = 0.82), which is an important determinant for PDT applications, increased. The photodynamic antimicrobial chemotherapy activity (PACT) of new Si(IV)Pc towards Staphylococcus aureus was determined in comparison to the unsubstituted SiPcCl2. The results of the photodynamic antimicrobial effect study demonstrated that the Pd(II) complex substituted SiPc (5) possesses excellent photodynamic activity with a reduction percentage value of 99.94% and a log red value of 3.26.
- Full Text:
- Date Issued: 2019
Biosynthesis of silver nanoparticles from Acacia mearnsii De Wild stem bark and its antinociceptive properties
- Avoseh, Opeyemi N, Oyedeji, Opeoluwa O, Aremu, Olukayode, Nkeh-Chungag, Benedicta N, Songca, Sandile P, Oyedeji, Adebola Omowunmi, Mohan, Sneha, Oluwafemi, Oluwatobi S
- Authors: Avoseh, Opeyemi N , Oyedeji, Opeoluwa O , Aremu, Olukayode , Nkeh-Chungag, Benedicta N , Songca, Sandile P , Oyedeji, Adebola Omowunmi , Mohan, Sneha , Oluwafemi, Oluwatobi S
- Date: 2017
- Subjects: Metal nanoparticles , Acacia mearnsii , Nociceptive pain
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/1528 , vital:37774 , https://doi.org/10.1080/17518253.2017.1287310
- Description: The biosynthesis of silver nanoparticles (Ag-NPs) using the hydrosol extract of the dry stem bark of Acacia mearnsii as reducing and capping agents, and their antinociceptive properties are hereby reported. By varying the temperature and reaction time, the temporal evolution of the optical and morphological properties of the as-synthesized material was investigated. The NPs were characterized by UV–visible absorption spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS) and x-ray diffractometry (XRD) The optical analyses show that the position of the maximum surface plasmon resonance (SPR) peak is red-shifted as the reaction temperature decreased. The TEM micrographs show that the as-synthesized Ag-NPs are spherical while the X-ray diffraction shows that the material is highly crystalline with face-centered cubic structures. The anti-inflammatory efficacy, analyzed by the formalin model, indicates that the as-synthesized Ag-NPs are very effective, with an inhibition rate of about 76%.
- Full Text:
- Date Issued: 2017
- Authors: Avoseh, Opeyemi N , Oyedeji, Opeoluwa O , Aremu, Olukayode , Nkeh-Chungag, Benedicta N , Songca, Sandile P , Oyedeji, Adebola Omowunmi , Mohan, Sneha , Oluwafemi, Oluwatobi S
- Date: 2017
- Subjects: Metal nanoparticles , Acacia mearnsii , Nociceptive pain
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/1528 , vital:37774 , https://doi.org/10.1080/17518253.2017.1287310
- Description: The biosynthesis of silver nanoparticles (Ag-NPs) using the hydrosol extract of the dry stem bark of Acacia mearnsii as reducing and capping agents, and their antinociceptive properties are hereby reported. By varying the temperature and reaction time, the temporal evolution of the optical and morphological properties of the as-synthesized material was investigated. The NPs were characterized by UV–visible absorption spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS) and x-ray diffractometry (XRD) The optical analyses show that the position of the maximum surface plasmon resonance (SPR) peak is red-shifted as the reaction temperature decreased. The TEM micrographs show that the as-synthesized Ag-NPs are spherical while the X-ray diffraction shows that the material is highly crystalline with face-centered cubic structures. The anti-inflammatory efficacy, analyzed by the formalin model, indicates that the as-synthesized Ag-NPs are very effective, with an inhibition rate of about 76%.
- Full Text:
- Date Issued: 2017
Tyrannical masters no more?: Promissory insurance warranties after Viking Inshore Fishing (Pty) Ltd v Mutual and Federal Insurance Co Ltd
- Authors: Glover, Graham B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186701 , vital:44526 , xlink:href="https://hdl.handle.net/10520/EJC-1b0c21b6eb"
- Description: Federal Insurance Co Ltd for the law on promissory insurance warranties are considered. The article begins with an overview of the traditional position, which has been that such warranties are to be strictly interpreted and enforced, no matter the harshness of the result. Thereafter, the article discusses the contrasting decisions in Viking Inshore Fishing (Pty) Ltd v Mutual and Federal Insurance Co Ltd in the Western Cape High Court and the SCA. Wallis JA suggested on appeal that the strict traditional approach to promissory warranties was no longer appropriate, but without having to decide the point. The article next considers the implications of an obiter dictum of the SCA, in a matter relating to a court exercising admiralty jurisdiction, on insurance law in general. Thereafter, the article proposes that Wallis JA’s comments indicate an important change to our law on promissory warranties, specifically in relation to the need for there to be a causal link between the insured’s breach of the warranty and the loss suffered, before an insurer may exercise the power to repudiate the contract. Although others have made the causal-link argument before, this article tries to explain and situate this development in two doctrinal contexts: the modern law on contractual interpretation; and the doctrine of public policy. A supplementary argument relates to the drawing together of the law on promissory warranties with the rules relating to cancellation for major breach, in cases where an insurer pursues that remedy.
- Full Text:
- Date Issued: 2019
- Authors: Glover, Graham B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186701 , vital:44526 , xlink:href="https://hdl.handle.net/10520/EJC-1b0c21b6eb"
- Description: Federal Insurance Co Ltd for the law on promissory insurance warranties are considered. The article begins with an overview of the traditional position, which has been that such warranties are to be strictly interpreted and enforced, no matter the harshness of the result. Thereafter, the article discusses the contrasting decisions in Viking Inshore Fishing (Pty) Ltd v Mutual and Federal Insurance Co Ltd in the Western Cape High Court and the SCA. Wallis JA suggested on appeal that the strict traditional approach to promissory warranties was no longer appropriate, but without having to decide the point. The article next considers the implications of an obiter dictum of the SCA, in a matter relating to a court exercising admiralty jurisdiction, on insurance law in general. Thereafter, the article proposes that Wallis JA’s comments indicate an important change to our law on promissory warranties, specifically in relation to the need for there to be a causal link between the insured’s breach of the warranty and the loss suffered, before an insurer may exercise the power to repudiate the contract. Although others have made the causal-link argument before, this article tries to explain and situate this development in two doctrinal contexts: the modern law on contractual interpretation; and the doctrine of public policy. A supplementary argument relates to the drawing together of the law on promissory warranties with the rules relating to cancellation for major breach, in cases where an insurer pursues that remedy.
- 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
Woza Albert! (Student Editions)
- Authors: Krueger, Anton
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229598 , vital:49691 , xlink:href="https://doi.org/10.1080/10137548.2018.1560975"
- Description: Publishing Woza Albert! back in 1983 was a smart move by Methuen Publishing, since it went on to become South Africa’s most canonical dramatic text. As Temple Hauptfleisch points out in his introduction to this new edition, the play has become one of the most anthologized and produced of all South African plays, a regular prescribed work…particularly so in the new curricula introduced since 1994…a major work in the South African literary canon, one of the most studied and produced of the plays from the turbulent 1980s.
- Full Text:
- Date Issued: 2019
- Authors: Krueger, Anton
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229598 , vital:49691 , xlink:href="https://doi.org/10.1080/10137548.2018.1560975"
- Description: Publishing Woza Albert! back in 1983 was a smart move by Methuen Publishing, since it went on to become South Africa’s most canonical dramatic text. As Temple Hauptfleisch points out in his introduction to this new edition, the play has become one of the most anthologized and produced of all South African plays, a regular prescribed work…particularly so in the new curricula introduced since 1994…a major work in the South African literary canon, one of the most studied and produced of the plays from the turbulent 1980s.
- Full Text:
- Date Issued: 2019
Exploring group solidarity for insights into qualities of T-learning
- Mudokwani, Kuda, Mukute, Mutizwa
- Authors: Mudokwani, Kuda , Mukute, Mutizwa
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390612 , vital:68568 , xlink:href="https://doi.org/10.3390/su11236825"
- Description: Across the world, organised groups of farmers participating in just and sustainability transformations encounter multiple obstacles. Through solidarity manifested in iterative processes of questioning, co-learning, collective action and reflection, and value creation for themselves and for others, some succeed in overcoming them. This article investigates how a district organic farmer association in Zimbabwe is encountering and handling group solidarity challenges arising from shifting from local to district level coordinated organic production and marketing. Based on the use of change laboratory, this paper explores solidarity at the local niche and networked district level to seek insights into the qualities of T-learning.
- Full Text:
- Date Issued: 2019
- Authors: Mudokwani, Kuda , Mukute, Mutizwa
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390612 , vital:68568 , xlink:href="https://doi.org/10.3390/su11236825"
- Description: Across the world, organised groups of farmers participating in just and sustainability transformations encounter multiple obstacles. Through solidarity manifested in iterative processes of questioning, co-learning, collective action and reflection, and value creation for themselves and for others, some succeed in overcoming them. This article investigates how a district organic farmer association in Zimbabwe is encountering and handling group solidarity challenges arising from shifting from local to district level coordinated organic production and marketing. Based on the use of change laboratory, this paper explores solidarity at the local niche and networked district level to seek insights into the qualities of T-learning.
- 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
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
Betty, Zorg and Me
- Authors: Krueger, Anton
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225552 , vital:49234 , xlink:href="https://doi.org/10.1080/00138398.2019.1636529"
- Description: This essay reminisces about the author’s encounters with Betty Blue at three different stages in his life. It reflects on stylistic elements of the film (as exemplar of Jean-Jacques Beineix’s Cinéma du look) as well as its portrayal of gender, sexuality, artistic aspiration and the concept of freedom. The essay also ruminates on the concept of having favourites and the synchronicity required to make a magical movie.
- Full Text:
- Date Issued: 2019
- Authors: Krueger, Anton
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225552 , vital:49234 , xlink:href="https://doi.org/10.1080/00138398.2019.1636529"
- Description: This essay reminisces about the author’s encounters with Betty Blue at three different stages in his life. It reflects on stylistic elements of the film (as exemplar of Jean-Jacques Beineix’s Cinéma du look) as well as its portrayal of gender, sexuality, artistic aspiration and the concept of freedom. The essay also ruminates on the concept of having favourites and the synchronicity required to make a magical movie.
- Full Text:
- Date Issued: 2019
Ectomycorrhizal fungal assessment of South African Pinus patula seedlings and their biological control potential to enhance seedling growth
- FitzGerald, Véronique Chartier
- Authors: FitzGerald, Véronique Chartier
- Date: 2019
- Subjects: Ectomycorrhizal fungi , Pinus patula Diseases and pests Biological control South Africa , Fusarium , Forest nurseries , Seedlings Growth , Seedlings Diseases and pests
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/67902 , vital:29167
- Description: The South Africa forestry industry, covering 1.3 million hectares, is dependent on exotic pine and eucalyptus species. Nursery seedlings are not inoculated with ectomycorrhizal (ECM) fungi or other beneficial microbes. Fusarium circinatum is an economically important pathogen affecting seedling survival. The purpose of this investigation was to assess levels of naturally occurring ECM colonisation in South African nurseries and to determine the effects of seedling inoculation with selected ECM and bacterial isolates on plant growth and resistance to the fungal pathogen F. circiantum. Pinus patula seedlings from 10 different South African nurseries were assessed for ECM colonisation using a grid line intersect method and molecularly identified using morphological and next-generation Illumina sequencing. Explants from ECM basidiocarps, collected from Pinus stands, were plated onto MMN medium to obtain isolates which were verified using molecular techniques. Mycorrhizal helper bacteria (MHB) were also isolated from these basiocarps, tested for MHB properties, siderophore production, phospahte solubilising and IAA production. ECM and associated bacterial isolates were used to inoculate seedlings and growth was assessed over a 5 month period. Colonisation of seedlings in production nurseries was low (2-21%). Morphologically the ECM fungi T. terrestris, Suillus sibiricus, and the genera Russula, Pseudotomentella were identified. Molecularly the ECM fungi T. terrestris, Inocybe jacobi and the genera Sphaerosporella and several other ECM containing families were identified along with many saprotrophic/endophytic fungi belonging to genera such as, Penicillium, Ramasonia and Talaromyces. Inoculated seedlings showed a significant increase in growth in comparison to the un-inoculated control seedlings. ECM fungal colonisation levels of these seedlings were significantly increased and colonisation was promoted by the Suillus isolate, Salmon Suillus. Seedling growth in the presence of the pathogen F. circinatum was significantly increased and promoted by the Lactarius isolate Lactarius quieticolor. Inoculation of seedlings in the nursery would ensure the production of stronger healthy plants which may be more tolerant to fusarial infection increasing survival in the plantation. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2019
- Full Text:
- Date Issued: 2019
- Authors: FitzGerald, Véronique Chartier
- Date: 2019
- Subjects: Ectomycorrhizal fungi , Pinus patula Diseases and pests Biological control South Africa , Fusarium , Forest nurseries , Seedlings Growth , Seedlings Diseases and pests
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/67902 , vital:29167
- Description: The South Africa forestry industry, covering 1.3 million hectares, is dependent on exotic pine and eucalyptus species. Nursery seedlings are not inoculated with ectomycorrhizal (ECM) fungi or other beneficial microbes. Fusarium circinatum is an economically important pathogen affecting seedling survival. The purpose of this investigation was to assess levels of naturally occurring ECM colonisation in South African nurseries and to determine the effects of seedling inoculation with selected ECM and bacterial isolates on plant growth and resistance to the fungal pathogen F. circiantum. Pinus patula seedlings from 10 different South African nurseries were assessed for ECM colonisation using a grid line intersect method and molecularly identified using morphological and next-generation Illumina sequencing. Explants from ECM basidiocarps, collected from Pinus stands, were plated onto MMN medium to obtain isolates which were verified using molecular techniques. Mycorrhizal helper bacteria (MHB) were also isolated from these basiocarps, tested for MHB properties, siderophore production, phospahte solubilising and IAA production. ECM and associated bacterial isolates were used to inoculate seedlings and growth was assessed over a 5 month period. Colonisation of seedlings in production nurseries was low (2-21%). Morphologically the ECM fungi T. terrestris, Suillus sibiricus, and the genera Russula, Pseudotomentella were identified. Molecularly the ECM fungi T. terrestris, Inocybe jacobi and the genera Sphaerosporella and several other ECM containing families were identified along with many saprotrophic/endophytic fungi belonging to genera such as, Penicillium, Ramasonia and Talaromyces. Inoculated seedlings showed a significant increase in growth in comparison to the un-inoculated control seedlings. ECM fungal colonisation levels of these seedlings were significantly increased and colonisation was promoted by the Suillus isolate, Salmon Suillus. Seedling growth in the presence of the pathogen F. circinatum was significantly increased and promoted by the Lactarius isolate Lactarius quieticolor. Inoculation of seedlings in the nursery would ensure the production of stronger healthy plants which may be more tolerant to fusarial infection increasing survival in the plantation. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2019
- Full Text:
- Date Issued: 2019
A return to common-sense: why ecology needs transcendental realism
- Authors: Price, Leigh
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390324 , vital:68538 , xlink:href="https://doi.org/10.1080/14767430.2019.1580178"
- Description: Empirical realist ecologists, such as C. S. Holling, face significant methodological contradictions; for instance, they must cope with the problem that ecological models and theories of climate change, resilience and succession cannot make predictions in open systems. Generally, they respond to this problem by supplementing their empirical realism with transcendental idealism: they therefore say that their models are simply metaphorical or heuristic, that is, 'not true' in that they are not empirical. Thus, they explicitly deny an ontology for what their models are about. Nevertheless, in their practice, ecologists act as if their theories do have an ontology and thus tell us something truthful about the real world. This discrepancy leaves ecology vulnerable to unnecessary critique, such as that climate science is not real science. Transcendental realism offers a solution because it releases ecologists from the requirement to make predictions; but it does so without denying ontology. This provides several advantages to ecologists.
- Full Text:
- Date Issued: 2019
- Authors: Price, Leigh
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390324 , vital:68538 , xlink:href="https://doi.org/10.1080/14767430.2019.1580178"
- Description: Empirical realist ecologists, such as C. S. Holling, face significant methodological contradictions; for instance, they must cope with the problem that ecological models and theories of climate change, resilience and succession cannot make predictions in open systems. Generally, they respond to this problem by supplementing their empirical realism with transcendental idealism: they therefore say that their models are simply metaphorical or heuristic, that is, 'not true' in that they are not empirical. Thus, they explicitly deny an ontology for what their models are about. Nevertheless, in their practice, ecologists act as if their theories do have an ontology and thus tell us something truthful about the real world. This discrepancy leaves ecology vulnerable to unnecessary critique, such as that climate science is not real science. Transcendental realism offers a solution because it releases ecologists from the requirement to make predictions; but it does so without denying ontology. This provides several advantages to ecologists.
- Full Text:
- Date Issued: 2019
Gem-bearing granitic pegmatites in Malawi: their mineralogy, geochemistry, age, and fluid compositional variations
- Kankuzi, Charles Frienderson
- Authors: Kankuzi, Charles Frienderson
- Date: 2019
- Subjects: Granite , Pegmatites , Geochemistry , Fluid inclusions , Nonferrous metals
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/97905 , vital:31505 , DOI https://doi.org/10.21504/10962/97905
- Description: The gem bearing granitic pegmatites from different pegmatite fields across Malawi intrude all important geological entities from the Palaeoproterozoic in the north, the Mesoproterozoic in central Malawi and the Pan-African basement in the south. U/Pb zircon and Rb/Sr mineral isochron ages indicate pegmatite emplacement from the Palaeoproterozoic to Pan-African and Mesozoic time. Most pegmatites are related to the Pan-African cycle; no Mesoproterozoic pegmatites were observed in this study. Within the Pan-African pegmatite groups there are two important subgroups. Some pegmatites show Sr isotopic compositions that indicate mantle components contributing to the parental granites from which the pegmatites evolved. Others show higher Sr initials, indicating crustal granites as primary pegmatite sources or significant crustal contamination. Only for few pegmatites, such as the Palaeoproterozoic and Ordovician gem tourmaline pegmatites in the Chitipa and Dowa Districts, the granitic source is evident from their field context. For all others the granitic origin is interpreted by mineralogical and geochemical evidence. All analysed pegmatites belong to either the Rare Element Class or the Miarolitic Class, but they vary in their degree of fractionation. The more evolved pegmatites are more enriched in incompatible elements such as Be, Li, B, and Ta, which resulted in the formation of gem minerals such as beryl, aquamarine, tourmaline and topaz, which may or may not be associated with tantalite. The Rare Element pegmatites can be further subdivided into the REL-Li subclass, beryl type, beryl-columbite subtype, and in the complex type and elbaite subtype. The Miarolitic pegmatites include Mi-Li subclass and beryl-topaz type. Fluid inclusion studies (heating-cooling stage, Raman spectroscopy) identified a variety of fluid compositions that were present at different times and different places, indicating a variety of fluid sources. They range from aqueous-saline to CO2–rich carbonic fluids (CO2 +C3H8+ N2), or aqueous-carbonic fluids (H2O-CO2-CH4 and H2O-CO2-H2-H2S-CH4). The dominant solutes and species for the pegmatites show genetic variations over time and orogen (Paleo-/Meso-/Neoproterozoic). Uniform homogenisation temperatures and salinities in individual samples indicate that the gem-bearing pegmatites contained homogeneous fluids at the time of their capturing in quartz. Based on fluid inclusion data, the estimated trapping conditions of inclusions in quartz for all studied pegmatites except for one pegmatite suggest low pressures between 0.9 to 2.6 kb at temperatures of 400-600 C. The other pegmatite formed at slightly higher pressures of 2.2 to 3.6 kb. However, the pressure range for all the pegmatites is in agreement with the known liquidus conditions of Rare-Element pegmatite crystallisation. The shallow crustal emplacement level (3.4-9.8 km) and the greater depth (8.3 to 13.6 km) favoured the formation of gemstones. , Thesis (PhD) -- Faculty of Science, Geology, 2019
- Full Text: false
- Date Issued: 2019
- Authors: Kankuzi, Charles Frienderson
- Date: 2019
- Subjects: Granite , Pegmatites , Geochemistry , Fluid inclusions , Nonferrous metals
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/97905 , vital:31505 , DOI https://doi.org/10.21504/10962/97905
- Description: The gem bearing granitic pegmatites from different pegmatite fields across Malawi intrude all important geological entities from the Palaeoproterozoic in the north, the Mesoproterozoic in central Malawi and the Pan-African basement in the south. U/Pb zircon and Rb/Sr mineral isochron ages indicate pegmatite emplacement from the Palaeoproterozoic to Pan-African and Mesozoic time. Most pegmatites are related to the Pan-African cycle; no Mesoproterozoic pegmatites were observed in this study. Within the Pan-African pegmatite groups there are two important subgroups. Some pegmatites show Sr isotopic compositions that indicate mantle components contributing to the parental granites from which the pegmatites evolved. Others show higher Sr initials, indicating crustal granites as primary pegmatite sources or significant crustal contamination. Only for few pegmatites, such as the Palaeoproterozoic and Ordovician gem tourmaline pegmatites in the Chitipa and Dowa Districts, the granitic source is evident from their field context. For all others the granitic origin is interpreted by mineralogical and geochemical evidence. All analysed pegmatites belong to either the Rare Element Class or the Miarolitic Class, but they vary in their degree of fractionation. The more evolved pegmatites are more enriched in incompatible elements such as Be, Li, B, and Ta, which resulted in the formation of gem minerals such as beryl, aquamarine, tourmaline and topaz, which may or may not be associated with tantalite. The Rare Element pegmatites can be further subdivided into the REL-Li subclass, beryl type, beryl-columbite subtype, and in the complex type and elbaite subtype. The Miarolitic pegmatites include Mi-Li subclass and beryl-topaz type. Fluid inclusion studies (heating-cooling stage, Raman spectroscopy) identified a variety of fluid compositions that were present at different times and different places, indicating a variety of fluid sources. They range from aqueous-saline to CO2–rich carbonic fluids (CO2 +C3H8+ N2), or aqueous-carbonic fluids (H2O-CO2-CH4 and H2O-CO2-H2-H2S-CH4). The dominant solutes and species for the pegmatites show genetic variations over time and orogen (Paleo-/Meso-/Neoproterozoic). Uniform homogenisation temperatures and salinities in individual samples indicate that the gem-bearing pegmatites contained homogeneous fluids at the time of their capturing in quartz. Based on fluid inclusion data, the estimated trapping conditions of inclusions in quartz for all studied pegmatites except for one pegmatite suggest low pressures between 0.9 to 2.6 kb at temperatures of 400-600 C. The other pegmatite formed at slightly higher pressures of 2.2 to 3.6 kb. However, the pressure range for all the pegmatites is in agreement with the known liquidus conditions of Rare-Element pegmatite crystallisation. The shallow crustal emplacement level (3.4-9.8 km) and the greater depth (8.3 to 13.6 km) favoured the formation of gemstones. , Thesis (PhD) -- Faculty of Science, Geology, 2019
- Full Text: false
- Date Issued: 2019
Fabrication of efficient nonlinear optical absorber using Zn phthalocyanine-semiconductor quantum dots conjugates
- Mgidlana, Sithi, Oluwole, David O, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187496 , vital:44663 , xlink:href="https://doi.org/10.1016/j.poly.2018.11.024"
- Description: In this paper, we report on the synthesis of Zn(II) phthalocyanine derivatives and their conjugates with core/shell and core/shell/shell semiconductor quantum dots (SQDs). Zn(II) mono amino-carboxyethylphenoxy phthalocyanine (1), Zn(II) mono 3-carboxyphenoxy-tris(pyridin-2-yloxy) phthalocyanine (2) and Zn(II) mono aminophenoxy-tris(benzothiazole) phthalocyanine (3) were synthesized. The photophysical and optical limiting properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs were investigated in dimethyl sulfoxide. The optical limiting behaviour of the Pc complexes and their conjugates were measured by the open aperture Z-scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. The conjugates outperformed the Pc complexes alone with the conjugates of 2-SQDs affording highest nonlinear absorption coefficient (βeff) value of ∼80 cm/GW and lowest limiting threshold (Ilim) value of ∼0.27 J·cm−2 as compared to other samples while complex 1 gave low βeff and high Ilim values of 42.2 cm/GW and 1.39 J·cm−2, respectively.
- Full Text:
- Date Issued: 2019
- Authors: Mgidlana, Sithi , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187496 , vital:44663 , xlink:href="https://doi.org/10.1016/j.poly.2018.11.024"
- Description: In this paper, we report on the synthesis of Zn(II) phthalocyanine derivatives and their conjugates with core/shell and core/shell/shell semiconductor quantum dots (SQDs). Zn(II) mono amino-carboxyethylphenoxy phthalocyanine (1), Zn(II) mono 3-carboxyphenoxy-tris(pyridin-2-yloxy) phthalocyanine (2) and Zn(II) mono aminophenoxy-tris(benzothiazole) phthalocyanine (3) were synthesized. The photophysical and optical limiting properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs were investigated in dimethyl sulfoxide. The optical limiting behaviour of the Pc complexes and their conjugates were measured by the open aperture Z-scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. The conjugates outperformed the Pc complexes alone with the conjugates of 2-SQDs affording highest nonlinear absorption coefficient (βeff) value of ∼80 cm/GW and lowest limiting threshold (Ilim) value of ∼0.27 J·cm−2 as compared to other samples while complex 1 gave low βeff and high Ilim values of 42.2 cm/GW and 1.39 J·cm−2, respectively.
- Full Text:
- Date Issued: 2019
Characterization of electrodes modified with nanocomposites of cobalt tetraaminophenoxyphthalocyanine, reduced graphene and multi-walled carbon nanotubes
- Shumba, Munyaradz, Nyoni, Stephen, Britton, Jonathan, Nyokong, Tebello
- Authors: Shumba, Munyaradz , Nyoni, Stephen , Britton, Jonathan , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187003 , vital:44555 , xlink:href="https://doi.org/10.1080/00958972.2019.1621299"
- Description: Glassy carbon electrodes or plates were modified with nanocomposites consisting of cobalt tetraaminophenoxyphthalocyanine (CoTAPhPc), reduced graphene oxide nanosheets (rGONs) and multi-walled carbon nanotubes (MWCNTs). The modified electrodes were characterized using cyclic voltammetry, scanning electrochemical microscopy (SECM) and time-of-flight-secondary ion mass spectrometer (TOF-SIMS). The electrocatalytic activity of the modified electrode was tested for detection of L-cysteine. The presence of CoTAPhPc on sequential layers of MWCNT and rGONs resulted in improved detection currents compared to CoTAPhPc alone or when MWCNT/rGONs are mixed in CoTAPhPc–MWCNT/ rGONs (mix)–glassy carbon electrode (GCE). CoTAPhPc–MWCNT–GCE (without rGONS) showed higher sensitivity toward L-cysteine as compared to the probes incorporating rGONs with a catalytic rate constant of 4.62x104 M-1 s-1 and a detection limit of 30 nM. The presence of rGONs improved the stability of the electrode.
- Full Text:
- Date Issued: 2019
- Authors: Shumba, Munyaradz , Nyoni, Stephen , Britton, Jonathan , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187003 , vital:44555 , xlink:href="https://doi.org/10.1080/00958972.2019.1621299"
- Description: Glassy carbon electrodes or plates were modified with nanocomposites consisting of cobalt tetraaminophenoxyphthalocyanine (CoTAPhPc), reduced graphene oxide nanosheets (rGONs) and multi-walled carbon nanotubes (MWCNTs). The modified electrodes were characterized using cyclic voltammetry, scanning electrochemical microscopy (SECM) and time-of-flight-secondary ion mass spectrometer (TOF-SIMS). The electrocatalytic activity of the modified electrode was tested for detection of L-cysteine. The presence of CoTAPhPc on sequential layers of MWCNT and rGONs resulted in improved detection currents compared to CoTAPhPc alone or when MWCNT/rGONs are mixed in CoTAPhPc–MWCNT/ rGONs (mix)–glassy carbon electrode (GCE). CoTAPhPc–MWCNT–GCE (without rGONS) showed higher sensitivity toward L-cysteine as compared to the probes incorporating rGONs with a catalytic rate constant of 4.62x104 M-1 s-1 and a detection limit of 30 nM. The presence of rGONs improved the stability of the electrode.
- Full Text:
- Date Issued: 2019
Electrocatalytic Activity of Asymmetrical Cobalt Phthalocyanines in the Presence of N Doped Graphene Quantum Dots: The Push-pull Effects of Substituents
- Nkhahle, Reitumetse, Sekhosana, Kutloano E, Centane, Sixolile, Nyokong, Tebello
- Authors: Nkhahle, Reitumetse , Sekhosana, Kutloano E , Centane, Sixolile , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186904 , vital:44546 , xlink:href="https://doi.org/10.1002/elan.201800837"
- Description: A series of Co phthalocyanine (CoPc) derivatives and their respective nitrogen doped graphene quantum dot conjugates were used as catalysts towards the electrooxidation of hydrazine. Using a glassy carbon electrode as a support for the electrocatalysts, through cyclic voltammetry and chronoamperometry, the effects of combining the CoPcs with the nitrogen doped graphene quantum dots (NGQDs) were studied. The general observations made were that the NGQDs improve the catalytic activity of the CoPcs in both the p-p stacked and covalently linked conjugates by increasing the sensitivities and lowering the limits of detection with values as low as 0.43 mM being recorded.
- Full Text:
- Date Issued: 2019
- Authors: Nkhahle, Reitumetse , Sekhosana, Kutloano E , Centane, Sixolile , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186904 , vital:44546 , xlink:href="https://doi.org/10.1002/elan.201800837"
- Description: A series of Co phthalocyanine (CoPc) derivatives and their respective nitrogen doped graphene quantum dot conjugates were used as catalysts towards the electrooxidation of hydrazine. Using a glassy carbon electrode as a support for the electrocatalysts, through cyclic voltammetry and chronoamperometry, the effects of combining the CoPcs with the nitrogen doped graphene quantum dots (NGQDs) were studied. The general observations made were that the NGQDs improve the catalytic activity of the CoPcs in both the p-p stacked and covalently linked conjugates by increasing the sensitivities and lowering the limits of detection with values as low as 0.43 mM being recorded.
- Full Text:
- Date Issued: 2019
Livelihood benefits and costs from an invasive alien tree (Acacia dealbata) to rural communities in the Eastern Cape, South Africa
- Ngorima, A, Shackleton, Charlie M
- Authors: Ngorima, A , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179755 , vital:43168 , xlink:href="https://doi.org/10.1016/j.jenvman.2018.05.077"
- Description: The negative effects of invasive alien species (IAS) are increasingly invoked to justify widespread and usually top-down approaches for their management or eradication. However, very little of the research or discourse is based on investigating local perceptions, uses and struggles with IAS, and how their presence influences and changes local livelihoods. The objective of this study was to assess the perceptions and livelihood uses of Acacia dealbata by local communities at three localities in the montane grasslands of the Eastern Cape, South Africa, using a combination of random household interviews, focus group discussions and participatory tools. We calculated direct-use values for each product and household (based on quantity used and local prices) and disaggregated these by gender of the household head and wealth quartiles. The results revealed the dualistic role of A. dealbata in local livelihoods. On the one hand, A. dealbata was widely used for firewood (100% of households), tools (77%) and construction timber (73%), with limited use for traditional medicines and forage. The cumulative value of approximately ZAR 2870 (±US$224) per household per year (across all households) represents considerable cash saving to households, most of whom are quite poor by national and international measures. On the other hand, the increasing extent of A. dealbata (93% said it was increasing) exacerbates local household vulnerability though reported reductions in cultivated areas, crop yields and forage production, and allegedly higher risks of crime. This quandary is well encapsulated by the considerable majority of respondents (84%) not wanting higher extents and densities of A. dealbata, but an equally high majority not wanting its total removal from local landscapes. Most respondents disliked A. dealbata in fields, close to homesteads or along primary access routes, and were more tolerant of it away from such sites. Institutional and use dynamics have varied over several decades in response to the changing extent and densities of A. dealbata and the broader political and socio-economic contexts. These results indicate that greater efforts are required to understand perceptions and uses of IAS by the people who live with them, and to direct such understanding into more spatially and temporally contextualised response strategies where required.
- Full Text:
- Date Issued: 2019
- Authors: Ngorima, A , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179755 , vital:43168 , xlink:href="https://doi.org/10.1016/j.jenvman.2018.05.077"
- Description: The negative effects of invasive alien species (IAS) are increasingly invoked to justify widespread and usually top-down approaches for their management or eradication. However, very little of the research or discourse is based on investigating local perceptions, uses and struggles with IAS, and how their presence influences and changes local livelihoods. The objective of this study was to assess the perceptions and livelihood uses of Acacia dealbata by local communities at three localities in the montane grasslands of the Eastern Cape, South Africa, using a combination of random household interviews, focus group discussions and participatory tools. We calculated direct-use values for each product and household (based on quantity used and local prices) and disaggregated these by gender of the household head and wealth quartiles. The results revealed the dualistic role of A. dealbata in local livelihoods. On the one hand, A. dealbata was widely used for firewood (100% of households), tools (77%) and construction timber (73%), with limited use for traditional medicines and forage. The cumulative value of approximately ZAR 2870 (±US$224) per household per year (across all households) represents considerable cash saving to households, most of whom are quite poor by national and international measures. On the other hand, the increasing extent of A. dealbata (93% said it was increasing) exacerbates local household vulnerability though reported reductions in cultivated areas, crop yields and forage production, and allegedly higher risks of crime. This quandary is well encapsulated by the considerable majority of respondents (84%) not wanting higher extents and densities of A. dealbata, but an equally high majority not wanting its total removal from local landscapes. Most respondents disliked A. dealbata in fields, close to homesteads or along primary access routes, and were more tolerant of it away from such sites. Institutional and use dynamics have varied over several decades in response to the changing extent and densities of A. dealbata and the broader political and socio-economic contexts. These results indicate that greater efforts are required to understand perceptions and uses of IAS by the people who live with them, and to direct such understanding into more spatially and temporally contextualised response strategies where required.
- Full Text:
- Date Issued: 2019