A Change Project story: learning and caring for South Africa’s rivers
- Authors: Chetty, Preven
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391060 , vital:68613 , xlink:href="https://eeasa.org.za/wp-content/uploads/2023/02/Final-EEASA-Bulletin-20212022-Final.pdf"
- Description: Water quality and scarcity is a major concern in Southern Africa and globally especially as the threat of climate change looms even closer. The current drought in South Africa and worsening rainfall has exposed the brittle nature of this country’s resilience to water shortages. Compounded to this is the fact that most rivers in South Africa are not adequately cared for and are under tremendous strain. Everyone who depends on these rivers whether directly or indirectly will soon be entering a new era where water will no longer be a ubiquitous commodity.
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- Date Issued: 2022
A laminated, emergentist view of skills ecosystems
- Authors: Ramsarup, Presha , Lotz-Sisitka, Heila , McGrath, Simon
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370074 , vital:66295 , xlink:href="https://doi.org/10.1080/14767430.2022.2145768"
- Description: In this paper we present a model of vocational education and training (VET) that can be used to guide decisions relating to VET in Africa today. This model takes the critique of the neoclassical, neoliberal model of VET as its starting point. Guided by Bhaskar's Critical Naturalism, we use immanent critique to consider the adequacy of proposed alternatives to the neoclassical approach, such as: the heterodox approach, which foregrounds explanations based on human capital and political economy; and Hodgson and Spours' social ecosystem model, which addresses some of the limitations of the heterodox account by including, social and ecosystem elements. Finally, we offer a version of the social ecosystem model that, according to our analysis, explains more of the empirical evidence than previous models. Our version of the social ecosystem model differs from earlier versions in terms of its explicit reference to the critical realist ideas of position- practices and emergence.
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- Date Issued: 2022
A simple quinoline-thiophene Schiff base turn-off chemosensor for Hg2+ detection
- Authors: Musikavanhu, Brian , Muthusamy, Selvaraj , Zhu, Dongwei , Xue, Zhaoli , Yu, Qian , Chivumba, Choonzo N , Mack, John , Nyokong, Tebello , Wang, Shengjun , Zhao, Long
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230362 , vital:49771 , xlink:href="https://doi.org/10.1016/j.saa.2021.120338"
- Description: A new Schiff base probe (QT) consisting of 8-aminoquinoline (Q) and thiophene-2-carboxaldehyde (T) moieties has been synthesized. QT undergoes chelation-enhanced fluorescence quenching when exposed to Hg2+ due to coordination by the sulfur and nitrogen atoms of QT thus forming a facile “turn-off” sensor. The formation of the chelation complex was confirmed by UV–visible absorption and emission spectral measurements, 1H NMR titration and density functional theory calculations. These studies revealed that the probe exhibits high selectivity and sensitivity towards Hg2+ in the presence of other common metal ions. A low detection limit of 23.4 nM was determined and a Job plot confirmed a 2:1 stoichiometry between QT and Hg2+. The potential utility of QT as a sensor for Hg2+ ions in human HeLa cells was determined by confocal fluorescence microscopy, and its suitability for use in the field with environmental samples was tested with Whatman filter paper strips.
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- Date Issued: 2022
A Sn (iv) porphyrin with mitochondria targeting properties for enhanced photodynamic activity against MCF-7 cells
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230897 , vital:49829 , xlink:href="https://doi.org/10.1039/D2NJ00350C"
- Description: Two readily synthesized Sn(IV) porphyrins (SnP, SnPH) have been prepared with and without the cationic triphenylphosphonium moiety (TPP+), which have high singlet oxygen quantum yields (ca. 0.72) and long triplet state lifetimes. The Sn(IV) porphyrin with a TPP+ moiety (SnPH) exhibits favorable photodynamic activity against MCF-7 cells with IC50 values of 2.9 μM. SnPH exhibits higher cellular uptake than SnP in MCF-7 cells. A Rhodamine 123 (Rh123) assay showed that SnPH targets mitochondria and induces apoptosis by generating reactive oxygen species. The results demonstrate that this structural modification strategy merits further in-depth study.
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- Date Issued: 2022
Adsorption of antibiotic-resistant bacteria and their cell-free deoxyribonucleic acid harbouring resistance genes in drinking water with metal oxides
- Authors: Tobechukwu, Anthony Eric
- Date: 2022
- Subjects: Metallic oxides , DNA -- Synthesis , Drinking water
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27787 , vital:69494
- Description: Access to cleaner water is essential to human health. The incidence of Antibiotic Resistant Bacteria ARB in drinking water and subsequent proliferation of Antibiotic Resistance Genes ARGs in drinking water is a concern for public health. The free DNA cassette harboring antibiotic resistance gene in drinking water has been linked with impaired public health. The ARGs allows bacteria to develop resistance towards antibiotics while ARB render antibiotics ineffective. Existing drinking water treatment technologies eg adsorption, ozonation and chlorination, have shown different levels of potency in the removal of conventional water pollutant. These technologies, which operating principles is based on oxidation or mass transfer, have been explored to gained an insight into their efficiency in the removal of ARB ARGs in water treatment. In general, methods that functions by mass transfer of the ARB ARGs is more effectively than bacteria oxidation. Consequently, adsorption technology was chosen using common metal oxide adsorbents. The adsorbents ZnOAg CeO2 and Al2O3 were synthesized via the self propagation combustion method. This method was selected because of the purity of the final product and the energy requirement. One of the challenges in the removal of ARB in drinking water is the release of ARGs. To address this concern, five different ZnOAg heterostructures were synthesized for the removal of Enterococci faecium. ZnOAg was chosen because of the bactericidal and bacteriostatic characteristics. The study revealed that the concentration of the precursors influences the microstructures of the adsorbents; however, it did not significantly affect the adsorption efficiency. The maximum adsorption capacity q34.11 CFUg was obtained for Ag1Zn3.5. The kinetic studies revealed that Ag1Zn1 and Ag1Zn2 adsorbents agreed to the pseudofirst-order kinetic equation and adsorbents Ag2Zn1 Ag3.5Zn1 and Ag1Zn3.5 agreed to the pseudo-second-order kinetic equation. Initial tap-water pH range was beneficial for the adsorption and the pH of the treated tap-water was within the WHO tap water recommendation 6.5 – 8.5 whereas the effect of ionic strength, anionic and cationic interference was insignificant in the adsorption of MDREF onto the different heterostructure. Interestingly the MDREF could retain its cell membrane integrity and resistance genes, suggesting that surface adsorption was the primary mechanism for the removal. Cerium IV oxide CeO2 was selected because of high adsorption towards phosphate, backbone base for DNA. To prevent the problem of antibiotic resistance, we have synthesized a CeO2 adsorbent that exhibit highly positive character in a wide pH range, via the simple self-propagation combustion protocol, for the removal of free DNA harboring antibiotic resistance genes. Molecular characterization of the extracted genes showed that the sizes for E. coli and inherent gyrB genes are 147 and 460 bp with a purity between 19 2.0. The XRD SEM TEM, and PZC results of the as-synthesized CeO2 showed an agglomerate of pure cubic-faced centered material and highly crystalline, with a net charge at pH 6.2. Experimental results revealed that the reaction proceeded via pseudo first-order kinetic, and it is governed by electrostatic attraction. The free- DNA solution pH electrolyte, and competing ions impacted on the adsorption process. Further experimental results showed that the as-synthesized CeO2 adsorbent has the potential to be used for the removal of free DNA harboring ARGs from tap-water even under oxic conditions. Alumina Al2O3 is an abundant adsorbent that has also shown high removal capacity towards phosphate. The highly pure synthesized Al2O3 adsorbent exhibit fluid-like behaviour under Scanning Electron Microscope SEM. The XRD pattern corresponds to αAl2O3. The adsorption kinetics was described by pseudo second orderadsorption capacity 11.7 μgg implying chemisorption, which agrees with the electrostatic force of attraction caused by opposing ions. This result was evident by the effect of different ions in the tap water. The synthesized α-Al2O3 has the potential for the removal of cell free DNA harbouring multiply resistant genes. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
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- Date Issued: 2022
African clay pot decorated with cream, brown and black bands
- Date: 2022 , 2022-10-06
- Subjects: Bam, Brigalia , Pottery, African
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/57004 , vital:57212
- Description: African clay pot, decorated with cream, brown and black bands. , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2022
African clay pot decorated with diagonal rust and brown patterns.
- Date: 2022 , 2022-10-10
- Subjects: Bam, Brigalia , Pottery, African
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/57063 , vital:57294
- Description: African clay pot decorated with diagonal rust and brown patterns. , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2022
African clay pot decorated with patterns in rust, brown and silver alloy
- Date: 2022 , 2022-10-10
- Subjects: Bam, Brigalia , Pottery, African
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/57045 , vital:57289
- Description: African clay pot decorated with patterns in rust, brown and silver alloy. , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2022
African clay pot decorated with patterns in rust, brown and silver alloy
- Date: 2022 , 2022-10-10
- Subjects: Bam, Brigalia , Pottery, African
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/57055 , vital:57291
- Description: African clay pot decorated with patterns in rust, brown and silver alloy. , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2022
African clay pot decorated with rust and brown abstract patterns
- Date: 2022 , 2022-10-10
- Subjects: Bam, Brigalia , Pottery, African
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/57079 , vital:57299
- Description: African clay pot decorated with rust and brown abstract patterns. , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2022
African clay pot with patterns in rust and brown
- Date: 2022 , 2022-10-10
- Subjects: Bam, Brigalia , Pottery, African
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/57075 , vital:57297
- Description: African clay pot with patterns in rust and brown. , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2022
African clay pot with rust, brown and silver patterns
- Date: 2022 , 2022-10-10
- Subjects: Bam, Brigalia , Pottery, African
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/57092 , vital:57300
- Description: African clay pot decorated with rust, brown and silver patterns. , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2022
African clay pot, decorated with rust, brown and silver alloy patterns
- Date: 2022 , 2022-10-10
- Subjects: Bam, Brigalia , Pottery, African
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/57025 , vital:57277
- Description: African clay pot, decorated with rust, brown and silver alloy patterns. , Women have acquired amazing skills in making African mats, baskets, pot, etc., to preserve African Art , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2022
African wooden bowl decorated with reed crocheted pattern
- Date: 2022 , 2022-10-10
- Subjects: Bam, Brigalia , Bowls (Tableware)
- Language: English
- Type: realia
- Identifier: http://hdl.handle.net/10948/57097 , vital:57302
- Description: African wooden bowl, with rust, light and dark brown decoration with black patterns. , Reed crocheted pattern around the mouth of the bowl. , Donated/gifted to Nelson Mandela University Archives , Forms part of: Brigalia Bam collection
- Full Text: false
- Date Issued: 2022
Application of gold and palladium nanoparticles supported on polymelamine microspheres in the oxidation of 1-phenylethanol and some other phenyl substituted alcohols
- Authors: Storm, Ené , Maggott, Emile D , Mashazi, Philani N , Nyokong, Tebello , Malgas-Enus, Rehana , Mapolie, Selwyn F
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/299824 , vital:57858 , xlink:href="https://doi.org/10.1016/j.mcat.2022.112456"
- Description: Melamine formaldehyde and melamine resorcinol formaldehyde microspheres were decorated with Au and Pd nanoparticles and applied as heterogeneous catalysts in the oxidation of 1-phenylethanol. The catalysts showed similar activities irrespective of the support employed. Moderate conversion activities of 48–50% were achieved when using acetonitrile as solvent; however, when employing water as solvent, the supported catalysts formed a three-phase, emulsion system which facilitated the catalytic conversion of 1-phenylethanol to acetophenone at much higher conversions of around 83%. The oxidant, TBHP, decomposed rapidly in acetonitrile, whilst it remained stable in aqueous solution, leading to the enhanced activities observed when using water as solvent. These systems also proved to be recyclable for up to five cycles, with only slight loss of activity observed; this can be attributed to the physical loss of catalyst during the workup procedure conducted between each cycle.
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- Date Issued: 2022
Aptamer versus antibody as probes for the impedimetric biosensor for human epidermal growth factor receptor
- Authors: Centane, Sixolile , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229884 , vital:49720 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2022.111764"
- Description: In the present work, the performance of aptamer and antibody bioreceptors for the detection of the human epidermal growth factor receptor (HER2) cancer biomarker on a glassy carbon electrode is reported. The carboxylic acid group rich graphene quantum dots (GQDs) modified with gold nanoparticles and a porphyrin binuclear framework (CoP-BNF) were used to modify the glassy carbon electrode. The aptamer and antibody were both amine functionalized and attached to GQDs and CoP-BNF through an amide bond. The designed immunosensors and aptasensors in this work were characterized using electrochemical impedance spectroscopy. The aptasensors, compared to the immunosensors gave better limit of detection values. The aptasensor outperforms the immunosensor in terms of its reusability and storability, while the immunosensor could not be regenerated for subsequent experiments. The potential applicability of all sensors in this work was also investigated, by detection of HER2 in spiked human serum with acceptable results.
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- Date Issued: 2022
Artisanal mining versus sustainability of agricultural food supply chains: effects of the conflicts in Southern Zimbabwe
- Authors: Chari, Felix , Novukela, Cawe , Ngcamu , Bethuel Sibongiseni
- Date: 2022
- Subjects: Traditional farming Small Scale mining Great Zimbabwe Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7082 , vital:52810 , xlink:href="https://doi.org/10.1080/23311886.2021.2002542"
- Description: This article seeks to establish the social and environmental consequences of artisanal mining on economic sustainability of agricultural food supply chains in Zimbabwe. Following a descriptive research design, interviews were conducted with 36 farmers. Interviewees were purposively sampled from potential respondents in Southern Zimbabwe. Interview results were triangulated with data from published reports and newspaper articles. Data was analysed using NVivo application version 12 and presented in vignettes. The results of this study are useful to artisanal miners, farmers, and government. Recommendations for further studies are given. KEYWORDS: Artisanal mining farmers food supply chains Zimbabwe sustainability
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- Date Issued: 2022
Assessing climate risk to support urban forests in a changing climate
- Authors: Esperon-Rodriguez, Manuel , Rymer, Paul D , Power, Sally A , Barton, David N , Cariñanos, Paloma , Dobbs, Cynnamon , Eleuterio, Ana A , Escobedo, Francisco J , Hauer, Richard , Hermy, Martin , Jahani, Ali , Onyekwelu, Jonathan C , Östberg, Johan , Pataki, Diane , Randrup, Thomas B , Rasmussen, Tørres , Roman, Lara A , Russo, Alessio , Shackleton, Charlie M , Solfjeld, Ingjerd , van Doorn, Natalie S , Wells, Matthew J , Wiström, Björn , Yan, Pengbo , Yang, Jun , Tjoelker, Mark G
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/402191 , vital:69829 , xlink:href="https://doi.org/10.1002/ppp3.10240"
- Description: Globally, cities are planning for resilience through urban greening initiatives as governments understand the importance of urban forests in improving quality of life and mitigating climate change. However, the persistence of urban forests and the ecosystem benefits they provide are threatened by climate change, and systematic assessments of causes of tree dieback and mortality in urban environments are rare. Long-term monitoring studies and adaptive management are needed to identify and prevent climate change-driven failures and mortality. Research and monitoring when coupled with systematic forecasting will enable governments to incorporate climate change resilience into urban forestry planning. Future scenarios in which urban forests are resilient or in decline will depend on the management and planning actions we make today.
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- Date Issued: 2022
Assessing the electrocatalytic activity of a localized push-pull system in cobalt phthalocyanine/graphene quantum dot hybrids
- Authors: Nkhahle, Reitumetse , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229909 , vital:49722 , xlink:href="https://doi.org/10.1016/j.matchemphys.2022.125842"
- Description: In this study, two cobalt phthalocyanines (asymmetric complex 1) and symmetric (complex 2) were synthesized and conjugated to nitrogen-doped graphene quantum dots (NGQDs) through covalent and non-covalent means to create Co phthalocyanine (CoPc)-NGQDs hybrid systems. The CoPcs and conjugates were applied as electrode modifiers on a glassy carbon electrode in the electrochemical sensing of nitrite. Of the CoPcs alone, complex 1 performed better than complex 2 regarding the limits of detection (LoD) recorded (5.74 μM for 1 and 15.1 μM for 2). Regarding the conjugates/nanocomposites, the π-π stacked conjugate derived from complex 2 (2πNGQDs) demonstrated highly favourable electrochemical potential with an LoD value of 0.70 μM. The nanocomposites fashioned from complex 1 were marred by a reduced loading which rendered the conjugates poor electrochemical sensors. These observations however do not disqualify GQDs as complementary nanomaterials to phthalocyanines but rather shed light on seeking alternative routes to increasing the Pc loading in conjugates (more so in π-π stacked conjugates).
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- Date Issued: 2022
Asymmetrical zinc (II) phthalocyanines conjugated to metal tungstate nanoparticles for photoinactivation of Staphylococcus aureus
- Authors: Mgidlana, Sithi , Managa, Muthumuni , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295718 , vital:57372 , xlink:href="https://doi.org/10.1080/00958972.2022.2090837"
- Description: In this study, we report for the first time on the photodynamic antimicrobial chemotherapy (PACT) of asymmetrical zinc(II) phthalocyanines and their conjugates with nickel tungstate (NiWO4), cobalt tungstate (CoWO4) and bismuth tungstate (Bi2WO6) nanoparticles. CoWO4, NiWO4 and Bi2WO6 were capped with glutathione and covalently linked to three asymmetrical zinc(II) phthalocyanines for PACT. The plate count method was used to investigate the effect of covalently linking asymmetrical zinc(II) phthalocyanines to nanoparticles under light (for PACT against Staphylococcus aureus) and in the dark. Both Pc complexes and the conjugates indicated minimum dark-toxicity. The conjugates showed greater antimicrobial activity against a gram-positive and drug resistant bacteria, Staphylococcus aureus, than Pc complexes alone.
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- Date Issued: 2022