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Small but strong: Socioeconomic and ecological resilience of a small European fishing community affected by a submarine volcanic eruption

- De la Cruz-Modino, Raquel, Piñeiro-Corbeira, Cristina, Gutiérrez-Barroso, Josué, González-Cruz, Carla, Barreiro, Rodolfo, Batista-Medina, José A, Pascual-Fernández, José, González, José A, Santana-Talavera, Agustín, Aswani, Shankar

  • Authors: De la Cruz-Modino, Raquel , Piñeiro-Corbeira, Cristina , Gutiérrez-Barroso, Josué , González-Cruz, Carla , Barreiro, Rodolfo , Batista-Medina, José A , Pascual-Fernández, José , González, José A , Santana-Talavera, Agustín , Aswani, Shankar
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/391397 , vital:68648 , xlink:href="https://doi.org/10.1016/j.ocecoaman.2022.106124"
  • Description: Small-scale coastal fishing communities are facing many new challenges, such as rapid ecological changes created by anthropogenic and natural events like earthquakes or volcanic eruptions. This paper explores how a coastal population has responded to such an event and highlights the diverse coping strategies used to tackle it. This research was conducted on the island of El Hierro (Spain), where a submarine volcanic eruption occurred in 2011, affecting a multiple-use Marine Protected Area (MPA) and the nearby fishing community of La Restinga. Our study illustrates how the local population coped with this situation by combining multiple monetary and non-monetary activities (e.g., informal exchanges) as well as the role of institutions in increasing local resilience by supporting fishers' demands and allowing their participation in the decision-making process in the immediate wake of a catastrophic event. Local families also exploited various natural resources in and near the MPA, thus ensuring access to crucial marine resources and continued recreational/cultural services. The results suggest that collective action played a key role in the recovery process after the eruption, creating some advantages for different local groups despite the hazardous nature of the event.
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  • Date Issued: 2022

Sn (IV) porphyrin-biotin decorated nitrogen doped graphene quantum dots nanohybrids for photodynamic therapy

- Magaela, N Bridged, Matshitse, Refilwe, Balaji, Babu, Managa, Muthumuni, Prinsloo, Earl, Nyokong, Tebello

  • Authors: Magaela, N Bridged , Matshitse, Refilwe , Balaji, Babu , Managa, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/230018 , vital:49733 , xlink:href="https://doi.org/10.1016/j.poly.2021.115624"
  • Description: Photodynamic therapy (PDT) is a minimally invasive therapeutic procedure for cancer treatment. This study focuses on the synthesis, photophysicochemical properties, and PDT activity of Sn (IV) porphyrin (2), when linked to biotin decorated nitrogen doped graphene quantum dots (B-NGQDs). The porphyrin complex 2 was conjugated through an ester bond to B-NGQDs to form 2-B-NGQDs. Singlet oxygen quantum yield increased for 2 when linked to B-NGQDs to form 2-B-NQGDs. The dark toxicity and photodynamic therapy studies were conducted for 2, NGQDs and their conjugates using MCF-7 breast cancer cells. The cell viability for dark toxicity of all the compounds was above 90%, and 2-B-NGQDs showed high PDT activity at a concentration of 40 µg/mL with cell viability of 22%.
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  • Date Issued: 2022

Social-ecological change: insights from the Southern African Program on Ecosystem Change and Society

- Biggs, Reinette, Clements, Hayley S, Cumming, Graeme S, Cundill, Georgina, de Vos, Alta, Hamann, Maike, Luvuno, Linda, Roux, Dirk J, Selomane, Odirlwe, Blanchard, Ryan, Cockburn, Jessica, Dziba, Luthando, Esler, Karen J, Fabricius, Christo, Henriksson, Rebecka, Kotschy, Karen, Lindborg, Regina, Masterson, Vanessa A, Nel, Jeanne L, O'Farrell, Patrick, Palmer, Carolyn G, Pereira, Laura, Pollard, Sharon, Preiser, Rika, Scholes, Robert J, Shackleton, Charlie M, Shackleton, Sheona, Sitas, Nadia, Slingsby, Jasper A, Spierenburg, Maria, Tengö, Maria, Reyers, Belinda

Structural modification of RhIIItriarylcorroles for enhanced electrocatalyzed hydrogen evolution reactions

- Zhu, Weihua, Li, Lihua, Wang, Yu, Mack, John, Dingiswayo, Somila, Nyokong, Tebello, Liang, Xu

  • Authors: Zhu, Weihua , Li, Lihua , Wang, Yu , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Liang, Xu
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/229933 , vital:49724 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.110046"
  • Description: A series of A3 type RhIIItriarylcorroles 2a-c with different meso-substituents with differing electron-donating and withdrawing properties and two A2B type RhIIItriarylcorroles 4a-b with meso-methylthiophenyls at the B position have been prepared and characterized. An analysis of structure-property relationships of 2a-c and 4a-b has been carried out by comparing the optical spectroscopy and electrochemistry of the dyes to trends predicted in DFT and TD-DFT calculations. Rational structural modification strategies that enhance the suitability of 2a-c for use as highly efficient catalysts for hydrogen evolution reactions on glassy carbon electrodes coated with 2a-c/reduced graphene oxide composites and of 4a-b in surface-modified Au electrodes are explored.
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  • Date Issued: 2022

Suitably Strange: Re-imagining learning, scholar-activism, and justice

- McGarry, Dylan K

  • Authors: McGarry, Dylan K
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/371005 , vital:66402 , xlink:href="https://hdl.handle.net/10520/ejc-cristal-v10-n1-a7"
  • Description: Using artworks emergent from my career as a pracademic and scholar activist, I attempt to share a ‘tactile theory’ of being and doing, that refer mainly to response-abilities (i.e., abilities to respond in accountable ways) in scholar activist educational sociology. I aim to make visible (and tactile) the sometimes-invisible qualities and practices needed for navigating the eroded and dying ecological relations of our generation, as well as warming up and making pliable the heteronormative, capitalist, patriarchal and anthropocentric conventions that are associated with it. In order to warm and sculpt these normative conventions, I argue for the need for ‘suitably strange’ practice. I present six images and associated prose that aim to optimally disrupt these conventions, towards generative rethinking and embodying learning, scholar activism and justice, and from which I explore a tactile theory, an example and related response-ability for each. I end with a reflection of how these suitably strange artefacts can help us develop a new concept of proactive-cognitive justice or ‘justness’.
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  • Date Issued: 2022

Symmetry effect of cobalt phthalocyanines on the aluminium corrosion inhibition in hydrochloric acid

- Nnaji, Nnaemeka, Sen, Pinar, Nyokong, Tebello

  • Authors: Nnaji, Nnaemeka , Sen, Pinar , Nyokong, Tebello
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/231323 , vital:49877 , xlink:href="https://doi.org/10.1016/j.matlet.2021.130892"
  • Description: The aluminium corrosion retardation potentials of phthalocyanine-based dyes, cobalt (II) 2,9,16-tris(4-(tert-butyl)phenoxy)-23-(pyridin-4-yloxy)phthalocyanine (D1) and cobalt (II) 2,9,16,24-tetrakis(4-(tert-butyl)phenoxy)phthalocyanine (D2) in 1 M hydrochloric acid were evaluated. Results from potentiodynamic polarization measurements show that inhibition efficiency increased with inhibitor concentration at 28 °C with values of 91.9 % and 87.0 % values respectively for D1 and D2 at 10 μM.
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  • Date Issued: 2022

Synergistic recognition and electrochemical sensing of 17β-Estradiol using ordered molecularly imprinted polymer-graphene oxide-silver nanoparticles composite films

- Regasa, Melkamu Biyana, Nyokong, Tebello

  • Authors: Regasa, Melkamu Biyana , Nyokong, Tebello
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/295829 , vital:57382 , xlink:href="https://doi.org/10.1016/j.jelechem.2022.116713"
  • Description: Synthetic molecularly imprinted polymers (MIPs) based functional materials become the best alternatives to alleviate the stability and cost issues related to biological receptors commonly used in biochemical sensors. To address this demand, we report the development of a highly selective and sensitive MIPs-based electrochemical sensor for the detection of 17β-estradiol (E2). The sensor was prepared based on the MIP-graphene oxide (GO)-silver nanoparticle (AgNP) nanocomposite functional materials electrodeposited on the surface of the glassy carbon electrode (GCE). At first, AgNp formation was facilitated by using ascorbic acid to reduce and stabilize it. A very stable MIP-GO-AgNP sensing layer with multifunctional units were formed using imidazole as a functional monomer (p-type-electron acceptor), GO (n-type-electron donor), and AgNP by using the electrodeposition method. The role of GO in the system is providing additional functional units to bind the template and improve materials morphology while that of AgNPs is acting as a catalyst and charge carrier. The characterization of the sensing materials was done by using Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray spectroscopy, and cyclic voltammetry. After optimization of the essential parameters, the sensor was successfully applied to detect the target analyte using the square wave voltammetric technique. The prepared sensor exhibited a wide linear range of 10 fM-250 nM with the limit of detection and limit of quantification of 3.01 fM and 10.03 fM, respectively. The high percentage recoveries, sensitivity, repeatability, and easy fabrication of the MIP-GO-AgNP materials made the proposed sensor promising for environmental monitoring applications in the future.
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  • Date Issued: 2022

Systematic review of genome-wide association studies of anxiety disorders and neuroticism

- Van Der Walt, Kristien, Campbell, Megan, Stein, Dan J, Dalvie, Shareefa

  • Authors: Van Der Walt, Kristien , Campbell, Megan , Stein, Dan J , Dalvie, Shareefa
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/302532 , vital:58205 , xlink:href="https://doi.org//10.1080/15622975.2022.2099970"
  • Description: Objectives: To summarise SNP associations identified by genome-wide association studies (GWASs) of anxiety disorders and neuroticism; to appraise the quality of individual studies, and to assess the ancestral diversity of study participants. Methods: We searched PubMed, Scopus, PsychInfo and PubPsych for GWASs of anxiety disorders, non-diagnostic traits (such as anxiety sensitivity), and neuroticism, and extracted all SNPs that surpassed genome-wide significance. We graded study quality using Q-genie scores and reviewed the ancestral diversity of included participants. Results: 32 studies met our inclusion criteria. A total of 563 independent significant variants were identified, of which 29 were replicated nominally in independent samples, and 3 were replicated significantly. The studies had good global quality, but many smaller studies were underpowered. Phenotypic heterogeneity for anxiety (and less so for neuroticism) seemed to reflect the complexity of capturing this trait. Ancestral diversity was poor, with 70% of studies including only populations of European ancestry. Conclusion: The functionality of genes identified by GWASs of anxiety and neuroticism deserves further investigation. Future GWASs should have larger sample sizes, more rigorous phenotyping and include more ancestrally diverse population groups.
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  • Date Issued: 2022

Technology Adoption Readiness in Disadvantaged Universities during COVID 19 Pandemic in South Africa

- Aruleba, Kehinde., Jere, Nobert., Matarirano, Obert.

  • Authors: Aruleba, Kehinde. , Jere, Nobert. , Matarirano, Obert.
  • Date: 2022
  • Subjects: Covid 19 Readiness for school Web-based instruction Article
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/11260/6544 , vital:46489 , xlink:href="https://doi.org/10.5430/ijhe.v11n2p172"
  • Description: The Covid 19 pandemic has affected hundreds of million lives and taken over four million lives to date. As a result, governments and policymakers see the need for emergency action to reduce the spread of the virus. In an attempt to contain the virus, governments and policymakers worldwide introduced a different range of prote ction measures and interventions to change their citizen's behaviours , primarily through social distancing, interprovince lockdown, stay at home strategies, and quarantines. The different lockdown measures have created unique and challenging conditions wit h no documented equivalent in the education sector. A significant effect was that many Higher Education institutions worldwide were not ready to switch to online teaching and learning when the governments announced the sudden lockdown. This study discusses the effect s of the Covid 19 pandemic on South Africa Higher Education Institution s , focusing on the historically disadvantaged universities. The study went further to evaluate the readiness of lecturers from selected disadvantaged universities to adopting online teaching and learning by applying the Technology Readiness Acceptance Model (TRAM). Quantitative data was collected through an online questionnaire. Results show that the higher the average of optimism and innovativeness among the respondents' poin t towards the readiness of adopting technology. On the other hand, higher the average insecurity and discomfort show the uneasiness of adopting technologies by the respondents.
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  • Date Issued: 2022

The contribution of wild palms to the livelihoods and diversification of rural households in southern Mozambique

- King, Angelina R, Shackleton, Charlie M

  • Authors: King, Angelina R , Shackleton, Charlie M
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/399846 , vital:69563 , xlink:href="https://doi.org/10.1016/j.forpol.2022.102793"
  • Description: In most low-income countries, rural households combine a range of economic activities to generate income, achieve food and nutritional security and fulfill other livelihood objectives, including: small-scale farming, fishing, hunting, livestock and timber production, and non-timber forest products gathering, as well as off-farm activities such as wage labour and informal trading. This work examines the role of diversification, including palm products income, on rural livelihoods in the Zitundo area, southern Mozambique. Seven livelihood strategies were identified, with every strategy combining cash income from several sources. Most households adopt a wage-based strategy to some degree, although this strategy shows low potential for reducing poverty in the area. Households adopting a palm-based strategy show between 23% and 60% lower poverty incidence than those adopting alternatives strategies. Yet, a palm-based livelihood strategy was adopted by only 11% of households. Traders of palm products earn approximately double the annual income and per capita income than non-traders. Village of residency and some household socio-economic and demographic characteristics correlate with a households' choice of livelihood strategy and palm income dependency. The adherence of many households to a less remunerative wage strategy indicates other factors also influence the choice of livelihood strategies. The study shows that future development plans and policy interventions to mitigate poverty in the area should go beyond the usual agricultural sector and recognize the role of non-timber forest products, especially palm products, for people's livelihoods and poverty alleviation.
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  • Date Issued: 2022

The effect of charge on Zn tetra morpholine porphyrin conjugated to folic acid-nitrogen doped graphene quantum dots for photodynamic therapy studies

- Magaela, N Bridged, Matshitse, Refilwe, Nyokong, Tebello

  • Authors: Magaela, N Bridged , Matshitse, Refilwe , Nyokong, Tebello
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/295840 , vital:57383 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.102898"
  • Description: Zinc tetra morpholine porphyrin (complex 2), and its quaternized derivative (complex 3) were synthesized and conjugated to folic acid decorated nitrogen doped graphene quantum dots (FA-NGQDs) through π−π stacking to study their photodynamic therapy (PDT) efficacy. Photophysiochemical properties of complexes 2, 3, and their conjugates (2-FA-NGQDs, 3-FA-NGQDs) were studied. It was found that complex 3 had higher ϕΔ of 0.56 compared to complex 2 with ϕΔ of 0.24, and respective composites: 3-FA-NGQDs had higher ϕΔ compared to 2-FA-NGQDs. The PDT studies were conducted for nanoparticles (FA-NGQDs), complexes (2, 3), and respective composites (2-FA-NGQDs, and 3-FA-NGQDs) using MCF-7 breast cancer cell. Dark toxicity of all compounds was above 90% which is negligible. At a highest concentration of 40 µg/mL, 3-FA-NGQDs gave the lowest cell viability of 28% compared to all other conjugates and porphyrins alone.
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  • Date Issued: 2022

The Electrocatalytic Detection of Nitrite Using Manganese Schiff Base Phthalocyanine Complexes

- Ndebele, Nobuhle, Nyokong, Tebello

  • Authors: Ndebele, Nobuhle , Nyokong, Tebello
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/295856 , vital:57385 , xlink:href="https://doi.org/10.1007/s12678-022-00752-4"
  • Description: This work investigates the use of manganese phthalocyanines (MnPcs) in the electrochemical detection of nitrite. These are two Schiff base derivatives: tetrakis 4-(4-thio-thiophene-2-ylmethanamino) phthalocyaninato Mn(III)Cl (2) and tetrakis 4-(3-(pyrrolidine-1-yl)propan-1-amino)phthalocyaninato Mn(III)Cl (3) and one aldehyde: tetrakis(4-formylphenoxy)phthalocyaninato Mn(III)Cl (1). The MnPc complexes were adsorbed onto the glassy carbon electrode surface using the drop-dry method and used as electrocatalysts to detect nitrite. Nitrite oxidation peak potentials obtained using cyclic voltammetry ranged between 0.70 and 0.84 V. Detection limits as low as 0.16 µM and sensitivity values as high as 276 µMmM−1 were obtained through the use of chronoamperometry. The Schiff base MnPcs 2 and 3 exhibited better nitrite detection properties (in terms of limit of detection and sensitivity) than their aldehyde precursor (1).
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  • Date Issued: 2022

The emergence of isiZulu in Skeem Saam (2011)

- Aiseng, Kealeboga

  • Authors: Aiseng, Kealeboga
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/277956 , vital:55335 , xlink:href="https://doi.org/10.1080/13504630.2022.2063115"
  • Description: This study aims to investigate how an ecological understanding of polyglossia is used in the South African Broadcasting Corporation’s (SABC) television channel, SABC 1 to maintain and create ethnolinguistic dominance. Key arguments this study will make are: (1) polyglossia is a language ideology masquerading as ethnolinguistic pluralism, (2) there is a loss of ethnolinguistic pluralism in SABC 1 because of the polyglot culture and its transmissions, (3) isiZulu is emerging as a language and cultural flare of the channel. This paper concluded that isiZulu’s presence is rising in a soap initially meant to be a Sepedi show. And this has negative consequences for language equality in the SABC.
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  • Date Issued: 2022

The genetic architecture of the corpus callosum and its subregions

- Campbell, Megan, Dalvie, Shareefa, Shadrin, Alexey, van der Meer, Dennis, Andreassen, Ola, Stein, Dan J, Rokicki, Jaroslav

  • Authors: Campbell, Megan , Dalvie, Shareefa , Shadrin, Alexey , van der Meer, Dennis , Andreassen, Ola , Stein, Dan J , Rokicki, Jaroslav
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/302542 , vital:58206 , xlink:href="https://doi.org/10.1016/j.euroneuro.2022.07.263"
  • Description: Background: Regional surface area and thickness of the cerebral cortex and volume of subcortical structures are highly heritable brain morphological features with complex genetic architectures, involving many common genetic variants with small effect sizes. However, the genetic architecture of the corpus callosum (CC) and its subregions remains largely unclear. We aim to determine the heritability and genetic architecture of CC volume and each subregion and the extent to which this overlaps with that of psychiatric disorders. Methods: Genetic and T1-weighted MRI data of 40,894 individuals from the UK-biobank was used to construct a multivariate GWAS. Here, we utilized a multivariate approach (Multivariate Omnibus Statistical Test, MOSTest) to assess the distributive effects of common variants across the five subregions of the CC (posterior, mid posterior, central, mid anterior and anterior) obtained by running the automatic subcortical segmentation algorithm in FreeSurfer 5.3. Gene-set enrichment analyses were performed using MAGMA. Linkage disequilibrium score regression was used to determine the SNP-based heritability of the CC and will be used to assess the genetic correlation between each subregion and a variety of psychiatric disorders. Results: Following MOSTest, 70 independent loci show pooled effects across the 5 subregions of the CC (p more than 5×10-8). Using LDSC, we found evidence to suggest that CC volume is heritable (h2SNP= 0.38, SE=0.03). Significant variants showed enrichment in pathways related to regulation of the nervous system and cell development, neurogenesis, and regulation of neuron differentiation. Gene-set analysis revealed 156 significant genes (p is less than 2.6x10-6). Many of the significant SNPs have been previously associated with white matter hyperintensity volume as well as a range of psychiatric disorders. Discussion: Here we provide the first preliminary evidence to suggest that volume of the CC is heritable. Gene set enrichment analyses identified pathways related to neuron development and neurogenesis, suggesting that CC alteration may have an independent developmental origin. Further investigation into the shared genetic architecture of CC subregions and psychiatric disorders may provide novel insight into disease manifestation.
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  • Date Issued: 2022

The implications of ortho-, meta-and para-directors on the in-vitro photodynamic antimicrobial chemotherapy activity of cationic pyridyl-dihydrothiazole phthalocyanines

- Magadla, Aviwe, Openda, Yolande Ikala, Nyokong, Tebello

  • Authors: Magadla, Aviwe , Openda, Yolande Ikala , Nyokong, Tebello
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/295875 , vital:57386 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.103029"
  • Description: Cationic Zn phthalocyanine complexes were derived by alkylation reaction of tetra-(pyridinyloxy) phthalocyanines (Pcs) at the ortho, meta, and para positions to form Zn (II) tetrakis 3-(4-(2-pyridin-1-ium-1-yl) butyl)-2-mercapto-4,5-dihydrothiazol-3-ium phthalocyanine (2), Zn (II) tetrakis 3-(4-(3-pyridin-1-ium-1-yl) butyl)-2-mercapto-4,5-dihydrothiazol-3-ium phthalocyanine (4) and Zn (II) tetrakis 3-(4-(4-pyridin-1-ium-1-yl) butyl)-2-mercapto-4,5-dihydrothiazol-3-ium phthalocyanine (6). The photophysicochemical behaviors of the Pc complexes were assessed. The meta and para-substituted complexes gave high singlet oxygen quantum yields. The cationic Pcs demonstrated good planktonic antibacterial activity against Staphylococcus aureus and Escherichia coli with the high log reduction values of 9.29 and 8.55, respectively. The cationic complexes also showed a significant decrease in the viability of in vitro biofilms after photo-antimicrobial chemotherapy at 100 µM for both Staphylococcus aureus and Escherichia coli biofilms.
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  • Date Issued: 2022

The in vitro photo-sonodynamic combinatorial therapy activity of cationic and zwitterionic phthalocyanines on MCF-7 and HeLa cancer cell lines

- Nene, Lindokuhle Cindy, Buthelezi, Khanyisile, Prinsloo, Earl, Nyokong, Tebello

  • Authors: Nene, Lindokuhle Cindy , Buthelezi, Khanyisile , Prinsloo, Earl , Nyokong, Tebello
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/295891 , vital:57387 , xlink:href="https://doi.org/10.1016/j.jphotochem.2022.114116"
  • Description: The syntheses and characterization studies of zwitterionic 2,9,16,23-tetrakis-(N-propane sultone-morpholino) zinc(II) (4) and 2,9,16,23-tetrakis-(2,5-dimethyl-4-(N-propane sultone-morpholinomethyl))-phenoxy zinc(II) (6) phthalocyanines are reported in this work. The photophysical properties, reactive oxygen species (ROS) generation and in vitro anticancer photodynamic (PDT), sonodynamic (SDT), and photo-sonodynamic combination (PSDT) therapy activities of the Pcs were studied and compared to their cationic counterparts: (2,9,16,23-tetrakis-(N-methyl-morpholino) Zn(II)Pc, 3), (2,9,16,23-tetrakis-(2,5-dimethyl-4-(N-methylmorpholine)-phenoxy) Zn(II)Pc, 5). The cationic Pcs maintained higher anticancer activity for all treatment types and had higher ROS generation compared to the zwitterionic Pcs. Singlet oxygen and hydroxyl radicals were generated during ultrasound and combination irradiations of the Pcs. The zwitterionic Pcs also generated carbon radicals under ultrasound and combination irradiations. The ability of the Pcs to generate ROS is essential for PDT, SDT and PSDT, thus making these Pcs potential anticancer probes for these treatment types. Furthermore, the Pcs demonstrated the ability to bind to bovine serum albumin protein.
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  • Date Issued: 2022

The photocatalytic properties of zinc phthalocyanines supported on hematite nanofibers for use against methyl orange and Staphylococcus aureus

- Mapukata, Sivuyisiwe, Britton, Jonathan, Nwahara, Nnamdi, Nyokong, Tebello

  • Authors: Mapukata, Sivuyisiwe , Britton, Jonathan , Nwahara, Nnamdi , Nyokong, Tebello
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/230184 , vital:49751 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113637"
  • Description: Heterogeneous photocatalysis is a promising approach for environmental remediation from contaminants including microorganisms and organic pollutants. In this work, hematite nanofibers are fabricated and modified with a novel monosubstituted Pc (4) as well as an asymmetrical tetrasubstituted Pc (5) with the aim of creating hybrid photocatalysts. The photocatalytic activities of the unmodified and phthalocyanine modified hematite nanofibers were compared based on their efficiencies in the photoinactivation of S. aureus and photooxidation of methyl orange. For both applications, the hybrid nanofibers were found to be more efficient photocatalysts than the unmodified hematite nanofibers. Comparison of the modified nanofibers (4-Fe2O3 and 5-Fe2O3) showed that they have comparable antibacterial activity while the 5-Fe2O3 nanofibers are the best for the photooxidation of methyl orange. The singlet oxygen generation efficiency, high activity, versatility, regenerability and thus reusability of the fabricated hybrid nanofibers makes them ideal candidates for real life water treatment studies.
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  • Date Issued: 2022

The prevalence, composition and distribution of forageable plant species in different urban spaces in two medium-sized towns in South Africa

- Garekae, Hesekia, Shackleton, Charlie M, Tsheboeng, Gaolathe

  • Authors: Garekae, Hesekia , Shackleton, Charlie M , Tsheboeng, Gaolathe
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/401300 , vital:69724 , xlink:href="https://doi.org/10.1016/j.gecco.2021.e01972"
  • Description: Globally, the importance of urban vegetation in the quality and maintenance of life in urban areas is increasingly recognized. As the basis of urban green infrastructure, urban vegetation provides a diversity of ecosystem services, including provisioning services. However, there is limited understanding of the potential of urban vegetation as a supply of forageable resources within urban landscapes. This study examined the prevalence and distribution of forageable plant species across different spaces in the towns of Potchefstroom and Thabazimbi, South Africa. A multi-stage sampling technique was employed for selecting study sites, with a total of 136 plots sampled. In total, 88 plant species (foraged and forageable) were encountered across the sample plots, with almost three-quarters (70%) being indigenous to South Africa. Most of the species had multiple uses, with medicine, food and firewood being the most common uses, in order of frequency. Species cover and richness significantly differed across the urban spaces, being markedly higher in protected areas as compared to other spaces. Moreover, five plant communities were identified, resembling various species uses. Overall, the findings show that the fragmented urban spaces are endowed with a diversity of forageable plant species, with many valuable to particular sectors of urban society, such as foragers. Moreover, the notable number of forageable plant species encountered across the different spaces demonstrates the potential of urban green infrastructure as a supply of provisioning and cultural ecosystem services. This provides the basis for the selection of a diversity of species in urban greening programs for enhancing liveability and overall well-being in urban areas.
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  • Date Issued: 2022

The synergistic effects of coupling Au nanoparticles with an alkynyl Co (II) phthalocyanine on the detection of prostate specific antigen

- Nxele, Siphesihle Robin, Nkhahle, Reitumetse, Nyokong, Tebello

  • Authors: Nxele, Siphesihle Robin , Nkhahle, Reitumetse , Nyokong, Tebello
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/230232 , vital:49756 , xlink:href="https://doi.org/10.1016/j.talanta.2021.122948"
  • Description: Prostate specific antigen (PSA) aptasensors are fabricated using a novel asymmetrically substituted Co phthalocyanine (CoPc), gold nanoparticles (AuNPs) and PSA-specific antigen. The fabricated aptasensors are: GCE-AuNPs-Aptamer, GCE@CoPc-Aptamer and GCE-AuNPs@CoPc-Aptamer (GCE = glassy carbon electrode). The fabricated sensors are characterized at each modification step to monitor the changes occurring at the sensor surface. Concentration studies were carried out using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) to determine detection limits. All the fabricated aptasensors were found to be highly specific and selective but the GCE-AuNPs@CoPc-Aptamer nanoconjugate performed the best. The aptasensors were also tested in spiked serum samples and detection limits, as well as % recoveries were determined. The results obtained showed that the GCE-AuNPs@CoPc-Aptamer has the potential to be used for clinical studies as the results agree with those obtained for detection of PSA in buffer.
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  • Date Issued: 2022

The thermal physiology of Lysathia sp.(Coleoptera: Chrysomelidae), a biocontrol agent of parrot’s feather in South Africa, supports its success

- Goddard, Matthew, Owen, Candice A, Grant, Martin D, Coetzee, Julie A

  • Authors: Goddard, Matthew , Owen, Candice A , Grant, Martin D , Coetzee, Julie A
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/417806 , vital:71487 , xlink:href="https://doi.org/10.1080/09583157.2022.2054949"
  • Description: The establishment success of biocontrol agents originating from tropical regions is often limited by climate when introduced in temperate regions. However, the flea beetle, Lysathia sp. (Coleoptera: Chrysomelidae), a biocontrol agent of Myriophyllum aquaticum (Vell.) Verdc. (Haloragaceae) in South Africa, is an effective agent in regions where other biocontrol agents of tropical aquatic weeds have failed due to winter-induced mortality. The development (degree-day model) and thermal tolerance (critical thermal minimum/maximum [CTmin/max] and lower/upper lethal limits [LLT/ULT50]) of Lysathia sp. were investigated to explain this success. The model predicted that Lysathia sp. could complete 6 to 12 generations per year in the colder regions of the country. The lower threshold for development (t0) was 13.0 °C and thermal constant (K) was 222.4 days, which is considerably lower than the K values of other biocontrol agents of aquatic weeds in South Africa. This suggests that above the temperature threshold, Lysathia sp. can develop faster than those other species and complete multiple life cycles in the cooler winter months, allowing for rapid population growth and thus improving M. aquaticum control. Furthermore, the CTmin of Lysathia sp. was 2.3 ± 0.2 °C and the CTmax was 49.0 ± 0.5 °C. The LLT50 was calculated as ∼ −7.0 °C and the ULT50 as ∼ 43.0 °C. These wide tolerance ranges and survival below freezing show why Lysathia sp. has established at cool sites and suggest that it may be a suitable agent for other cold countries invaded by M. aquaticum.
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  • Date Issued: 2022
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