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Inhibition of aluminium corrosion using benzothiazole and its phthalocyanine derivative

  • Authors: Nnaji, Nnaemeka , Nwaji, Njemuwa , Fomo, Gertrude , Mack, John , Nyokong, Tebello
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/186949 , vital:44550 , xlink:href="https://doi.org/10.1007/s12678-019-00538-1"
  • Description: Cyclic voltammetry and potentiodynamic polarization techniques were used to study the effects of 4-[4-(1,3-benzothiazol2yl)phenoxy] phthalonitrile (BT) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride (ClGaBTPc) as aluminium corrosion inhibitors in 1.0 M hydrochloric acid. The presence of the inhibitors in the concentration range of 2 to 10 μM was found to retard the aluminium corrosion process such that the inhibition efficiency was found to range from 28.2 to 76.1% for BT and from 71.5 to 82.7% for ClGaBTPc. The latter was a better inhibitor. Scanning electron microscopy and energy-dispersive X-ray measurements reveal effective metal surface protection by the inhibitors, most probably by shielding it from the corrosion attacks of Cl− from the acid. The calculated quantum chemical parameters agreed with experimental results.
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  • Date Issued: 2019

Morphological identification of fungi associated with Eichhornia crassipes (Mart.-Solms) Laubach in the Wouri River Basin, Douala, Cameroon

  • Authors: Voukeng, Kenfack S N , Coombes, Candice A , Weyl, Philip S R , Djeugoue, F , Hill, Martin P
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/423785 , vital:72093 , xlink:href="https://doi.org/10.2989/16085914.2019.1636760"
  • Description: In many parts of the world, excess growth of Eichhornia crassipes (Pontederiaceae) poses a serious threat to aquatic environments. In Cameroon, where manual clearing is still undertaken, little is known about fungal diversity associated with the plant, or its potential for biological control. Surveys of the Wouri River Basin in the Littoral Region of Cameroon were conducted during a rainy season (May–October 2014) and a dry season (November 2015–April 2016) at various sites, to identify fungi associated with water hyacinth. Fungi were isolated and identified from symptomatic plant parts collected. In the rainy season, 130 fungal isolates belonging to 12 genera were identified morphologically, whereas 299 isolates belonging to 23 genera were identified during the dry season. With the exception of Fusarium oxysporum and Phytophthora sp., the genera represented new records for Cameroon, and Chaetomium strumarium, Colletotrichum gloesporioides, C. acutatum, C. dematium, Curvularia pallescens and Pytomyces chartarum were considered new host records for E. crassipes in Africa. Isolates of Acremonium zonatum, Chaetomium strumarium, Alternaria eichhorniae, Phytophthora sp. and Rhizoctonia sp. showed the highest frequency of occurrence on E. crassipes in the Wouri River Basin and, given their record as plant pathogens, could be potentially useful in the development of mycoherbicides for this weed in Cameroon.
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  • Date Issued: 2019

Rebellion and revolution

  • Authors: Tabensky, Pedro
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/305721 , vital:58606 , xlink:href="https://doi.org/10.1080/0969725X.2019.1574085"
  • Description: In this piece I will focus on what I think is a central aspect of Albert Camus’s thinking, embodied in the distinction he makes in The Rebel between rebel and revolutionary. His is a philosophy of rebellion and he thinks that revolutions are a distorted expression of our need to rebel against that which we cannot accept. His views should serve as a counterpoint to those who think that an all-or-nothing approach to social change is desirable (those who, for instance, are too quick to justify murderous campaigns allegedly aimed at justice). And the issue here is not that embodied crudely in the reactionary (or conservative)/radical dichotomy. Rather, it is a defence of the need to rebel within limits, not so much to preserve the old against the threat of the new but, instead, to preserve basic human decency from the dark side of outrage, without dismissing what is crucial about outrage and emancipatory struggles.
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  • Date Issued: 2019

A critical review of sanctioned knowledge production concerning abortion in Africa: Implications for feminist health psychology

  • Authors: Macleod, Catriona I , Chiweshe, Malvern T , Mavuso, Jabulile M-J J
  • Date: 2018
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/444212 , vital:74207 , xlink:href="https://doi.org/10.1177/1359105316644294"
  • Description: Taking a feminist health psychology approach, we conducted a systematic review of published research on abortion featured in PsycINFO over a 7-year period. We analysed the 39 articles included in the review in terms of countries in which the research was conducted, types of research, issues covered, the way the research was framed and main findings. Despite 97per cent of abortions performed in Africa being classifiable as unsafe, there has been no engagement in knowledge production about abortion in Africa from psychologists, outside of South Africa. Given this, we outline the implications of the current knowledge base for feminism, psychology and feminist health psychology in Africa.
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  • Date Issued: 2018

Evidence for a new regime shift between floating and submerged invasive plant dominance in South Africa

  • Authors: Strange, Emily F , Hill, Martin P , Coetzee, Julie A
  • Date: 2018
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/423993 , vital:72114 , xlink:href="https://doi.org/10.1007/s10750-018-3506-2"
  • Description: Classical biological control for the management of floating invasive plants has been highly successful in South Africa. However, restoring ecosystem services has been compromised by a new suite of submerged invasive plants. This study proposes that biological control of floating invasive macrophytes acts as a catalyst in a regime shift between floating and submerged invasive plant dominance. Regime shifts are large and sudden changes in the structure and functioning of ecosystems. The proposed shift is driven by the rapid decomposition of floating plants and subsequent increase in availability of nutrients and light. A mesocosm experiment explored the effect of biological control on floating Pistia stratiotes L. (Araceae) upon the growth of invasive submerged Egeria densa Planch. (Hydrocharitaceae), and native submerged plant species of the same family; Lagarosiphon major (Ridl.) Moss (Hydrocharitaceae). The results revealed a cascade effect of biological control of P. stratiotes on the availability of nitrogen, resulting in increased relative growth rates and invasive capacity for E. densa. In contrast, the native L. major could not compete with healthy or damaged P. stratiotes. These findings highlight the vulnerability of South African freshwater systems to submerged plant invasions and demonstrate the importance of a more holistic approach to invasive plant management.
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  • Date Issued: 2018

In-situ synthesis of gold nanoparticles on graphene quantum dots-phthalocyanine nanoplatforms: First description of the photophysical and surface enhanced Raman scattering behaviour

  • Authors: Nwahara, Nnamdi , Achadu, Ojodomo John , Nyokong, Tebello
  • Date: 2018
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/187638 , vital:44682 , xlink:href="https://doi.org/10.1016/j.jphotochem.2018.04.011"
  • Description: Owing to the need for new low-dimensional molecular assemblies with tailored electronic properties, the current study presents a facile approach for the synthesis and assembly of gold nanoparticles (AuNPs) onto functional graphene quantum dots (GQDs)-phthalocyanines (Pcs) arrays and the investigation of their photophysical and surface enhanced Raman scattering (SERS) properties. The GQDs were functionalized with L-glutathione (GSH) (to form GQDs@GSH) in order to assist coupling to the low symmetry Zn tris–(tert–butyl) mono carboxyphenoxy (propionic acid) phthalocyanine (complex 1) to form 1@GQDs. The affinity of gold (Au) to sulphur (S) was exploited for the assembly of the AuNPs onto 1@GQDs platform to form 1@GQDs-AuNPs. Transmission electron microscopic investigations confirmed the formation of monodispersed, spherical Pc/GQDs@GSH/AuNPs hybrids. The nanocomposite displayed high triplet quantum yields, which translated into high singlet oxygen quantum yield as high as 87%. Furthermore, the formed composites demonstrated strong surface enhanced Raman scattering (SERS) properties with an unprecedented intrinsic maximal enhancement factor of more than 30-fold. These nanostructures also retain more than 90% of their original SERS intensities after a week of storage, displaying superb stability under ambient conditions. These results highlight the remarkable potential of this composite as a unique Raman-based PDT dosimetric agent.
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  • Date Issued: 2018

In-situ synthesis of gold nanoparticles on graphene quantum dots-phthalocyanine nanoplatforms: First description of the photophysical and surface enhanced Raman scattering behaviour

  • Authors: Nwahara, Nnamdi , Achadu, Ojodomo John , Nyokong, Tebello
  • Date: 2018
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/188183 , vital:44730 , xlink:href="https://doi.org/10.1016/j.jphotochem.2018.04.011"
  • Description: Owing to the need for new low-dimensional molecular assemblies with tailored electronic properties, the current study presents a facile approach for the synthesis and assembly of gold nanoparticles (AuNPs) onto functional graphene quantum dots (GQDs)-phthalocyanines (Pcs) arrays and the investigation of their photophysical and surface enhanced Raman scattering (SERS) properties. The GQDs were functionalized with L-glutathione (GSH) (to form GQDs@GSH) in order to assist coupling to the low symmetry Zn tris–(tert–butyl) mono carboxyphenoxy (propionic acid) phthalocyanine (complex 1) to form 1@GQDs. The affinity of gold (Au) to sulphur (S) was exploited for the assembly of the AuNPs onto 1@GQDs platform to form 1@GQDs-AuNPs. Transmission electron microscopic investigations confirmed the formation of monodispersed, spherical Pc/GQDs@GSH/AuNPs hybrids. The nanocomposite displayed high triplet quantum yields, which translated into high singlet oxygen quantum yield as high as 87%. Furthermore, the formed composites demonstrated strong surface enhanced Raman scattering (SERS) properties with an unprecedented intrinsic maximal enhancement factor of more than 30-fold. These nanostructures also retain more than 90% of their original SERS intensities after a week of storage, displaying superb stability under ambient conditions. These results highlight the remarkable potential of this composite as a unique Raman-based PDT dosimetric agent.
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  • Date Issued: 2018

Synthesis, characterization and DPPH scavenging activity of some benzimidazole derivatives

  • Authors: Odame, Felix , Krause, Jason , Hosten, Eric C , Betz, Richard , Lobb, Kevin A , Tshentu, Zenixole R , Frost, Carminita L
  • Date: 2018
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/447209 , vital:74592 , xlink:href="https://dx.doi.org/10.4314/bcse.v32i2.8 "
  • Description: A base-catalyzed conversion of aldehydes to benzimidazoles has been achieved. The compounds have been characterized by IR, NMR, micoranalysis, and GC-MS. The reaction for the formation of benzimidazoles has been monitored with 1 H NMR and IR. The crystal structures of two derivatives, 2-(2- chlorophenyl)-1H-benzimidazole and 2-(1H-benzimidazol-2-yl)-4-nitrophenol, are presented. A study of the DPPH scavenging activity of these compounds showed that 2-(1H-benzimidazol-2-yl)phenol (2), 2-p-tolyl-1Hbenzimidazole (3) and 2-(4-methoxyphenyl)-1H-benzimidazole (7) gave IC50 values 1974, 773 and 800 µM.
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  • Date Issued: 2018

Trophic ecology of adult male Odonata. I. Dietary niche metrics by foraging guild, species, body size, and location

  • Authors: Chari, Lenin D , Moyo, Sydney , Richoux, Nicole B
  • Date: 2018
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/456379 , vital:75508 , xlink:href="https://doi.org/10.1111/een.12458"
  • Description: 1. Information on the dietary niches of adult odonates is sparse, as they are highly mobile and evasive animals, which makes them difficult to observe in their natural habitat. Moreover, there is a lack of knowledge on how varying behavioural traits of odonates relate to phenomena like niche partitioning. 2. This study investigated niche partitioning amongst odonate species, foraging guilds and size classes in a riverine system in the Eastern Cape province of South Africa. A combination of stable isotope and fatty acid‐based niches was used to infer odonate feeding. 3. Both fatty acid and stable isotope‐based niches showed that there was niche separation amongst odonates that forage in flight (fliers) and those that forage from a perch (perchers), amongst odonates of different size classes (damselflies, medium‐ and large‐sized dragonflies), and amongst species, although varying levels of niche overlap were observed in each case. 4. Niche sizes of odonates varied between an upstream and a downstream site. Generally greater niche overlap was recorded at the narrow upstream site (associated with low insect emergence rates) than the wider downstream site (associated with high insect emergence rates), indicating that a greater degree of resource sharing occurred at the upstream site where aquatic food was less abundant. 5. The findings of this study suggest that dietary niches of odonates can be influenced by foraging guild, body size, and/or environmental conditions, and additional study in a variety of regions is recommended to determine the greater applicability of these findings.
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  • Date Issued: 2018

Articulating reproductive justice through reparative justice: case studies of abortion in Great Britain and South Africa

  • Authors: Macleod, Catriona I , Beynon-Jones, Siân , Toerien, Merran
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/444237 , vital:74209 , xlink:href="https://doi.org/10.1080/13691058.2016.1257738"
  • Description: Public health and rights-based approaches to abortion advocacy are well established. Feminists are, however, increasingly using a broader framework of ‘reproductive justice’, which considers the intersecting conditions that serve to enhance or hinder women’s reproductive freedoms, including their capacities to decide about the outcome of their pregnancies. Nonetheless, reproductive justice approaches to abortion are, conceptually, relatively under-developed. We introduce a reparative justice approach as a method of further articulating the concept of reproductive justice. We first explain how this approach can be used to conceptualise safe, accessible and supportive abortion as a key element of reproductive justice in relation to the injustice of unwanted or unsupportable pregnancies. Using Ernesto Verdeja’s critical theory of reparative justice and case studies of two countries (South Africa and Great Britain) where abortion is legal, we show how such an approach enables an analysis of reproductive justice within the specificities of particular contexts. We argue that both the rights-based legal framework adopted in South Africa and the medicalised approach of British law have, in practice, limited reparative justice in these contexts. We discuss the implications of reparative justice for abortion advocacy.
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  • Date Issued: 2017

Challenges of information and communication technology policy implementation in rural South Africa

  • Authors: Chisango, Grasia , Lesame, Carol
  • Date: 2017
  • Subjects: Information society , Digital inclusion , Education
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/11260/5592 , vital:44611 , https://doi.org/10.18820/24150525/Comm.v22.4
  • Description: While the South African government has implemented an information and communication technology (ICT) policy to address issues of universal access and service, questions remain about the effective implementation of this policy in rural areas. This article explores the extent to which ICT policy and regulation were implemented in rural South Africa, with specific reference to the Eastern Cape province. Focus group interviews and in-depth face-to-face interviews were conducted to collect qualitative data from 28 high school learners, two local municipal mayors and two women support group leaders in the Chris Hani District Municipality. A theme analysis indicated that the Universal Service and Access Agency of South Africa (USAASA) is failing to fulfil its mandate of promoting universal access and service. It is recommended that the provincial government in the Eastern Cape design an ICT strategy for its municipalities and that there should be easy access to Thusong Service Centres in rural areas.
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  • Date Issued: 2017

Education in the Anthropocene: Ethico-moral dimensions and critical realist openings

  • Authors: Olvitt, Lausanne L
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/372753 , vital:66620 , xlink:href="https://doi.org/10.1080/03057240.2017.1342613"
  • Description: Human-induced changes in planetary bio-geo-chemical processes have tipped earth into a newly-proposed geological epoch: the Anthropocene, which places moral and ethical demands on people regarding who should take responsibility for the well-being of people and planet, how, and why. Drawing generally on critical realist ontology, and more particularly on Roy Bhaskar’s concept of the person as a ‘four-planar social being’ living in the world as a laminated ontological whole, the article examines the dimensions of people’s ethico-moral engagement with the Anthropocene and considers what types of learning processes might enable people to understand, live in, and co-create this period known as ‘the Anthropocene’ in just, care-filled and—where necessary—transformative ways. The article points to the need for a radical re-orientation of education systems in the light of ethico-moral challenges that come to prominence in the Anthropocene, and argues for learning processes that nurture individual and collective moral agency through transformative, even transgressive, learning processes that are relational, humble, interdisciplinary, multi-perspectival, systemic, reality-congruent and contextually responsive.
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  • Date Issued: 2017

Improved nonlinear optical behaviour of ball type indium (III) phthalocyanine linked to glutathione capped nanoparticles

  • Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
  • Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
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  • Date Issued: 2017

Investigation of photophysicochemical properties of zinc phthalocyanines conjugated to metallic nanoparticles

  • Authors: Dube, Edith , Nwaji, Njemuwa , Oluwole, David O , Mack, John , Nyokong, Tebello
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/233425 , vital:50089 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.09.020"
  • Description: The syntheses of zinc(II) tetra–[3–(4–phenoxy) (propanoic acid) phthalocyanine] (2) and zinc(II) mono–[3–(4–phenoxy) (propanoic acid) phthalocyanine (3) are reported in this work. Compounds 2 and 3 were covalently linked to glutathione capped silver (AgNPs–GSH), gold (AuNPs–GSH) and silver-gold alloy (Ag3Au1NPs–GSH) nanoparticles (NPs) via an amide bond formation to afford the conjugates: 2–AgNPs–GSH, 3–AgNPs–GSH, 2–AuNPs–GSH, 3–AuNPs–GSH, 2-Ag3Au1NPs–GSH and 3-Ag3Au1NPs–GSH. The photophysicochemical behaviours of the compounds and their conjugates with NPs were assessed in solution. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet quantum yields in comparison to the compounds. Accordingly, the AgNPs and AuNPs conjugates with the compounds afforded high singlet quantum yields. On the contrary, the conjugates of the alloy afforded decreased singlet quantum yields probably due to the screening effect. The compounds and their conjugates with NPs could serve as a viable and efficacious photosensitizer for photodynamic therapy.
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  • Date Issued: 2017

Multiple drivers of local (non-) compliance in community-based marine resource management: Case studies from the South Pacific

  • Authors: Rohe, Janne R , Aswani, Shankar , Schlüter, Achim , Ferse, Sebastian
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/420445 , vital:71744 , xlink:href="https://doi.org/10.3389/fmars.2017.00172"
  • Description: The outcomes of marine conservation and related management interventions depend to a large extent on people's compliance with these rule systems. In the South Pacific, community-based marine resource management (CBMRM) has gained wide recognition as a strategy for the sustainable management of marine resources. In current practice, CBMRM initiatives often build upon customary forms of marine governance, integrating scientific advice and management principles in collaboration with external partners. However, diverse socio-economic developments as well as limited legal mandates can challenge these approaches. Compliance with and effective (legally-backed) enforcement of local management strategies constitute a growing challenge for communities—often resulting in considerable impact on the success or failure of CBMRM. Marine management arrangements are highly dynamic over time, and similarly compliance with rule systems tends to change depending on context. Understanding the factors contributing to (non-) compliance in a given setting is key to the design and function of adaptive management approaches. Yet, few empirical studies have looked in depth into the dynamics around local (non-) compliance with local marine tenure rules under the transforming management arrangements. Using two case studies from Solomon Islands and Fiji, we investigate what drives local (non-) compliance with CBMRM and what hinders or supports its effective enforcement. The case studies reveal that non-compliance is mainly driven by: (1) diminishing perceived legitimacy of local rules and rule-makers; (2) increased incentives to break rules due to market access and/ or lack of alternative income; and (3) relatively weak enforcement of local rules (i.e., low perceptions of risk from sanctions for rule-breaking). These drivers do not stand alone but can act together and add up to impair effective management. We further analyze how enforcement of CBMRM is challenged through a range of institutional; socio-cultural and technical/financial constraints, which are in parts a result of the dynamism and ongoing transformations of management arrangements. Our study underlines the importance of better understanding and contextualizing marine resource management processes under dynamic conditions for an improved understanding of compliance in a particular setting.
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  • Date Issued: 2017

Nonlinear optical dynamics of benzothiazole derivatized phthalocyanines in solution, thin films and when conjugated to nanoparticles

  • Authors: Nwaji, Njemuwa , Jones, Benjamin M , Mack, John , Oluwole, David O , Nyokong, Tebello
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/190426 , vital:44993 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.05.042"
  • Description: Benzothiazole phthalocynines complexes: tetrakis[(benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] indium(III) chloride (1) and tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] indium(III) chloride (2) were synthesisized and their nanosecond nonlinear optical behaviours in solution, solid state and when conjugated to metallic nanoparticles were examined and compared to those of the corresponding ZnPc and GaPc which are designated as: tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] zinc(II) (3), tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5) and tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6). Trends in the electronic structures were identified through a comparison of the UV–vis absorption and magnetic circular dichroism (MCD) spectroscopy of the complexes and calculated spectra predicted by time dependent density functional theory (TD-DFT). Of all the complexes and nanoconjugates, complex 2 (containing sulphur linkages and In as a central metal) gave the best optical limiting behaviour.
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  • Date Issued: 2017

Platinum nanoparticles supported on carbon nanodots as anode catalysts for direct alcohol fuel cells

  • Authors: Gwebu, Sandile Surprise , Nomngongo, Philiswa Nosizo , Mashazi, Philani Nkosinathi , Maxakato, Nobanathi Wendy , Nyokong, Tebello
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/233118 , vital:50058 , xlink:href="https://doi.org/10.20964/2017.07.09"
  • Description: Carbon nanodots (CNDs) were successfully synthesized employing a cheap and green method using oats as a starting material. The Pt/CNDs electrocatalyst was synthesized using carbon nanodots as a reductant and support material without adjusting the pH of the solution. The synthesized materials were characterized using Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller Nitrogen adsorption (BET), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Inductively coupled plasma optical emission spectroscopy (ICP-OES). The FTIR results proved that the synthesized carbon nanodots contain carboxylic acid functional groups which facilitate the attachment of Pt nanoparticles. The BET surface area for carbon nanodots was found to be 312.5 m2 g -1 two times higher than that of commercial carbon. XPS results revealed the composition of the materials and the oxidation states of Pt in Pt/CNDs electrocatalyst. TEM images proved that the materials were of the nanoscale. XRD peaks proved that the carbon nanodots were amorphous and Pt (111) was present in the Pt/CNDs electrocatalyst. ICPOES determined the platinum concentration in Pt/CNDs electrocatalyst to be 8.12%. The electrochemical oxidation of methanol and ethanol were studied by cyclic voltammetry (CV) and chronoamperometry (CA). Cyclic voltammetry results showed that the Pt/CNDs electrocatalyst prepared by this method exhibit superior performance for methanol and ethanol electro-oxidation at room temperature.
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  • Date Issued: 2017

South African Learners’ Conceptual Understanding about Image Formation by Lenses

  • Authors: John, Merlin , Molepo, Jacob Maisha , Chirwa, Max
  • Date: 2017
  • Subjects: South Africa Lenses Journal article
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/11260/6000 , vital:45074 , xlink:href="https://doi.org/10.12973/eurasia.2017.00694a"
  • Description: The purpose of this research was to explore South African Grade 11 learners’ conceptual understanding of ‘image formation by lenses’. The participants for this study were 70 Grade 11 learners from a selected senior secondary school in Mthatha, Eastern Cape Province, South Africa. The qualitative approach employed in the study made use of a two-tier open-ended questionnaire as the data collection instrument. The study explored several alternative conceptions the learners had held in terms of the roles that the lens and the screen play in the image formation and the characteristics of the image formed when a lens with a larger diameter is used and when a portion of the lens is covered. Most of the participants could not respond correctly in the situations presented in the questionnaire. However, almost all of them were found to have adequate conceptual understanding about the role of a lens in the image formation.
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  • Date Issued: 2017

The contradictory conceptions of research in historically black universities

  • Authors: Muthama, Evelyn , McKenna, Sioux
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/187183 , vital:44577 , xlink:href="http://dx.doi. org/10.18820/2519593X/pie. v35i1.10"
  • Description: Research is conceptualised in multiple and contradictory ways within and across Historically Black Universities (HBUs) with consequences for knowledge production. Under the apartheid regime, research was deliberately underdeveloped in such institutions and this continues to have an impact. We argue that if HBUs are to move from the constraints of the past into the possibilities of the future, there is a need for a thorough understanding both of how research is currently conceptualised, and of the consequences of such conceptions for research output. We used a critical discourse analysis of interviews, documents and survey data from seven HBUs to identify the dominant discourses about the purposes of research. The findings are four dominant conceptions of research that sometimes contradict each other across and within the HBUs. These are research as integral to academic identity; research for social justice; research as an economic driver and research as an instrumentalist requirement for job security, promotion and incentives. These conceptions seemed to emerge in part because of the history of the institutions and create both constraining and enabling effects on research production.
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  • Date Issued: 2017

The contribution of NTFP trade to rural livelihoods in different agro-ecological zones of South Africa

  • Authors: Mugido, Worship , Shackleton, Charlie M
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/398370 , vital:69404 , xlink:href="https://doi.org/10.1505/146554817821865063"
  • Description: In South Africa, there is extensive NTFP trade within communities and via external markets. However, there is a limited indication of the proportion of all households trading one or more NTFPs, and how it varies in relation to local context. Therefore, this study sought to establish the proportion of households trading in NTFPs in sites of different distances to urban markets and agro-ecological zones of South Africa. The results showed that about 6.4% households reported selling NTFPs for various reasons, with many (22%) citing the need to earn cash income and limited employment opportunities (16.9%). Even though the returns from trading NTFPs are relatively low, every earning is very important to many cash-strapped rural households. This was demonstrated by the fact that many sellers of NTFPs used their earnings to augment household income and cover their living expenses.
  • Full Text: false
  • Date Issued: 2017
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