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South African nose flies (Diptera, Calliphoridae, Rhiniinae): taxonomy, diversity, distribution and biology

  • Authors: Thomas-Cabianca, Arianna , Villet, Martin H , Martínez-Sánchez, Anabel , Rojo, Santos
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/441400 , vital:73884 , 10.3897/BDJ.11.e72764
  • Description: Rhiniinae (Diptera, Calliphoridae) is a taxon of nearly 400 known species, many of them termitophilous. Approximatelly 160 valid species in 16 genera are Afrotropical, with over 60 of them occurring in South Africa. The taxonomy of this group is outdated, as most studies of the South African taxa were conducted 40 to 70 years ago (mostly by Salvador Peris and Fritz Zumpt). Published information on their biology and ecology is also scarce.
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  • Date Issued: 2023

The binary order of things: A discursive study of nursing students’ talk on providing, and learning about, LGBT patient care

  • Authors: Pinto, Pedro , Macleod, Catriona I , Nhamo-Murire, Mercy
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/441343 , vital:73878 , xlink:href="https://doi.org/10.1080/00918369.2022.2048163"
  • Description: Against the backdrop of the healthcare inequities and maltreatment facing LGBT patients, recommendations have been made for the inclusion of LGBT health topics in nursing curricula. Based on data collected in focus group discussions with South African nursing students, we complicate the assumption that training focused on health-specific knowledge will effectively reform providers’ prejudicial practices. Findings reveal ambivalence: silence and discrimination versus inclusive humanism. Participants drew on discourses of ignorance, religion, and egalitarian treatment to justify their inadequacy regarding LGBT patients; while doing so, however, they deployed othering discourses in which homophobic and transphobic disregard is rendered acceptable, and “scientifically” supported through binary, deterministic views of sexuality and gender. Such “expert” views accord with Foucault’s notion of “grotesque discourse.” We conclude with a discussion of the findings’ implications for nursing education; we call for the recognition and teaching of binary ideology as a form of discursive violence over LGBT lives.
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  • Date Issued: 2023

The Case for a Cray on a Chip

  • Authors: Machanick, Philip
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/439277 , vital:73561 , https://www.researchgate.net/profile/Siphamandla-Mncu-be/publication/375376322_Shadow_Information_Technology_in_the_Advent_of_Open_Educational_Resources/links/65485042ce88b87031c92188/Shadow-Information-Technology-in-the-Advent-of-Open-Educational-Resources.pdf#page=22
  • Description: Moore’s Law is usually interpreted as a prediction of how many transistors you can buy for the same money at some future date. It can also be interpreted as how long you need to wait until a given number of transistors falls below a target price. An example of this reverse-application of Moore’s Law is transitions such as the emergence of microprocessors competitive with traditional larger-scale computers and the emergence of smartphones. Since the late 1990s, it has become increasingly common for growth in transistors to equate to more CPUs (cores) per die. Recent designs have over 50 billion transistors and far more potential parallelism than can be supported by memory. I argue the case for a rebalancing of design goals with a much larger, faster on-chip memory and a CPU that is designed around this memory system. The proposal: a Cray-class vector CPU on a die with 1 Gibyte of static RAM, or Crayon (for Cray on a chip). The kind of organization classically used by Cray vector supercomputers is feasible to achieve on a single chip. I argue that a design like this can use the available memory bandwidth, as opposed to over-CPU designs with a large number of cores and GPU threads that are memory limited and propose how such a design could be used.
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  • Date Issued: 2023

The concurrent impacts of drought and leaf harvesting on two traditional African vegetable non-timber forest product species

  • Authors: Sinasson, Gisele K , Shackleton, Charlie M
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/399832 , vital:69562 , xlink:href="https://doi.org/10.1371/journal.pone.0283900"
  • Description: Investigating the concurrent impacts with harvesting on wild vegetables can guide their sustainable management while contributing to the understanding of such impacts on NTFP species. This study investigated leaf production, morphological and growth responses to the concurrent impacts of drought and leaf harvesting between two wild vegetables. A randomized greenhouse experiment was implemented with 1,334 plants of Amaranthus sp. and 391 of B. pilosa. A drought treatment was first implemented through six levels of drought stress and a control treatment. The harvesting treatment consisted of four harvesting levels and was implemented twice. Measurements were recorded before first and second harvests and at end of experiment. Data were separated into two periods (after first and second harvests) and analyzed using Multivariate Analysis of Variance and log-linear analysis. The results showed significant effects of drought on both species. However, Amaranthus sp. appeared more resilient to reduction in the daily amount of water than reduction in the frequency, while B. pilosa was resilient under both facets of drought stress. For Amaranthus sp., basal diameter, its growth, leaf production and survival increased with increase in the harvesting level (with some exceptions) after first harvest. After second harvest, there was decrease in plant height and leaf production. In B. pilosa, the impact was only significant on survival and leaf production (after first harvest). The effect of the interaction of the two drivers was significant for Amaranthus sp., but not for B. pilosa. The results also highlighted the possible negative impact of a prolonged high rate harvesting on the species performance, especially under severe drought. Basal diameter, its growth, survival and leaf production appeared more resilient to reduced amounts of watering in Amaranthus sp., and under both types of drought stress for B. pilosa. This suggests that both species could be sustained under medium drought stress.
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  • Date Issued: 2023

The importance of long-term post-release studies in classical biological control: Insect–plant monitoring and public awareness of water hyacinth management (Pontederia crassipes) in Dique Los Sauces, Argentina

  • Authors: Faltlhauser, Ana C , Jiménez, Nadia L , Righetti, Tomas , Visintin, Andrés M , Torrens, Javier , Salinas, Nicolás A , Mc Kay, Fernando , Hill, Martin P , Cordo, Hugo A , Sosa, Alejandro J
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/424828 , vital:72187 , xlink:href="https://doi.org/10.1111/eea.13355"
  • Description: Several components of classical biological control (CBC) programmes are necessary to assess the success of the management strategy (e.g., post-release monitoring) and also help prevent reintroductions or resurgences of invasive species (e.g., public awareness). Water hyacinth, Pontederia (= Eichhornia) crassipes (Mart.) Solms (Pontederiaceae) is an aquatic plant naturally distributed in the north-eastern region of the Del Plata basin in Argentina. In the 1960s it was introduced into the Dique Los Sauces reservoir located outside of its native range in La Rioja Province, in western Argentina, where it became invasive. The natural enemy, Neochetina bruchi Hustache (Coleoptera: Curculionidae), was intentionally introduced in 1974 to control the weed. To assess the success of this CBC programme, a long-term post-release study was conducted. Between 1965 and 2023, we monitored plant coverage, estimated N. bruchi densities, and quantified the associated damage by reanalysing previously published data and incorporating new sampling. We also conducted an online survey to analyse public knowledge and perception about this programme. Water hyacinth coverage fluctuated from its first record in 1965 (maximum coverage 90%) until the control of germinated plants (coverage 0%) in 2018. The plant decline was accompanied by an increase in the weevil population. In our survey, out of 325 respondents only a small group of mostly middle-aged and elderly people knew that the restoration had been achieved through a management strategy and even fewer were aware of the biocontrol approach taken. Respondents who had a positive approach to biological control were more aware of the management plan than respondents who had neutral or negative opinions. Neochetina bruchi has played a key factor in the control of P. crassipes. The intrinsic dynamics of these populations, the dormant seed bank, and the lack of public awareness support the need for long post-release evaluations including outreach campaigns to make a sustainable successful management programme.
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  • Date Issued: 2023

The in-vitro proliferation-suppression of MCF-7 and HeLa cell lines mediated by differently substituted ionic phthalocyanines in sonodynamic therapy supplemented-photodynamic therapy

  • Authors: Nene, Lindokuhle Cindy , Nyokong, Tebello
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/360461 , vital:65090 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2022.112084"
  • Description: This work focuses on the study of the effects of the ultrasonic frequency (MHz) and power (W.cm−2) on the stability, reactive oxygen species yields and cytotoxicity activities of differently substituted ionic phthalocyanines (Pcs) in sonodynamic therapy (SDT). Four ultrasonic parameters were investigated: Par I (1 MHz: 1 W.cm−2), Par II (1 MHz: 2 W.cm−2), Par III (3 MHz: 1 W.cm−2) and Par IV (3 MHz: 2 W.cm−2). A higher degradation of the Pcs was observed with increasing power at the Par II. Two reactive oxygen species (ROS) were detected in the ultrasound treated Pcs: singlet oxygen and hydroxyl radicals. Due to minimal degradation of most Pcs, Par I was chosen for SDT, photodynamic therapy (PDT), and photo-sonodynamic therapy (PSDT) against Michigan Cancer Foundation-7 and Henrietta Lacks cancer cell lines. PSDT generally showed improved therapeutic efficacies of the Pcs compared to the SDT and PDT mono treatments.
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  • Date Issued: 2023

The prevalence, uses and cultural assimilation of shrub and tree invasive alien plants in a biodiversity hotspot along the Wild Coast, South Africa

  • Authors: Wootton, Oscar , Shackleton, Charlie M
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/401314 , vital:69725 , xlink:href="https://doi.org/10.1080/26395916.2023.2216804"
  • Description: Invasive alien plant species (IAPS) frequently offer both ecosystem services and disservices to rural communities with high livelihood dependency on local landscapes. However, biocultural relationships with IAPS may go deeper than just provisioning uses, as they may be assimilated into local belief systems manifest in them becoming embedded in cultural constructions such as naming, stories, songs and ceremonies. It is likely that IAPS that are culturally assimilated will represent a greater conflict of interest in the face of proposed controls of IAPS in biodiversity hotspots where conservation priorities are frequently deemed paramount by external agencies. Using a mixed-methods approach we undertook roadside surveys of 17 selected IAPS along the 250 km Wild Coast section of the Maputaland-Pondoland-Albany biodiversity hotspot, accompanied by questionnaire interviews with 48 local people. The mean number of IAPS per site was four, ranging from zero (only one site) to ten, and local inhabitants deemed the abundance of all but one of the species to be increasing. All species had been in the region for decades, had a vernacular name, and all but one had direct consumptive uses. Species with multiple uses were more widely recognised. However, there was only marginal incorporation of the IAPS into stories, songs and ceremonies, although medicinal uses of some IAPS were for cultural/spiritual needs rather than physical ailments per se. These results show that despite widespread use, there was as yet relatively limited cultural assimilation of the IAPS in the Wild Coast region.
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  • Date Issued: 2023

The Southern African Program on Ecosystem Change and Society: an emergent community of practice

Transboundary Fisheries Management in Kavango–Zambezi Transfrontier Conservation Area (KAZA-TFCA): Prospects and Dilemmas

  • Authors: Imbwae, Imikendu , Aswani, Shankar , Sauer, Warwick H H , Hay, Clinton J
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/391433 , vital:68651 , xlink:href="https://doi.org/10.3390/su15054406"
  • Description: Inland fisheries in the Kavango–Zambezi Transfrontier Conservation Area (KAZA-TFCA) offer food security to the riverine communities across the region. They also contribute towards the attainment of the United Nations’ Sustainable Development Goals 1 and 15, which aim to alleviate poverty and maintain biodiversity conservation. Despite this significant role, the fisheries have suffered severe declines in the previous decades due to multiple factors, such as overfishing and poor legislation. Furthermore, climate change is exerting pressure by altering the ecology and productivity of the river systems. The unprecedented challenges of the COVID-19 pandemic have further constrained management efforts. Attempts to address these challenges have pointed towards transboundary fisheries management as a silver bullet in moving towards sustainable fisheries management. However, the implementation of this strategy in the region has encountered numerous roadblocks, thereby subjecting the river ecosystem to a wider environmental threat, with dire consequences on livelihoods. This paper reviews existing management and governance structures together with key informant interviews to elicit primary and secondary data essential for management at the regional level. The study identifies conflicting regulations, and inadequate policies and institutions across the region as major bottlenecks affecting the successful implementation of transboundary fisheries management. Finally, the paper offers some suggestions for the improvement of fisheries management in the region.
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  • Date Issued: 2023

TVET SI: Evaluating Boundary Crossing Social Learning in Vocational Education and Training: A value creation approach

  • Authors: Lotz-Sisitka, Heila , Sisitka, Lawrence , Chakona, Gamuchirai , Matiwane, Mandilive L , Matambo, Chamu
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/389925 , vital:68495 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/238540"
  • Description: This article focuses on the development and application of an evaluation model and approach for evaluating boundary crossing social learning in a Vocational Education and Training (VET) learning network in South Africa, with an emphasis on a Training of Trainers (ToT) course that helped to catalyse and strengthen this learning network via two iterations of the course over an eight-year period. The article shares how we adapted the value creation framework (VCF) of Wenger, Traynor and De Laat (2011; Wenger and Wenger-Traynor, 2020) in the evaluation of a VET Training of Trainers (ToT) programme and learning network that focussed on the uptake and circulation of rainwater harvesting and conservation (RWHandC) knowledge in a particular formal and informal VET context in the Eastern Cape, South Africa, where smallholder farmers were struggling to find water for producing food. The evaluated ToT course was catalytic in establishing a boundary crossing social learning network approach in a VET context that linked formal and informal VET (Lotz-Sisitka et al., 2016; Lotz-Sisitka et al., 2022; Pesanayi, 2019); hence we found it important to develop adequate tools for its evaluation. The focus of this article is to share how we developed an evaluation approach to this work. We share insights on the indicators developed for diff erent types of value created, and also insights gained into the use of this evaluation approach in a boundary crossing VET social learning project that took a ToT course as focus. In short, evaluation findings show that the boundary crossing ToT course off ers strong immediate, potential and applied value that can lead to realised and reframed value, especially if supported by ongoing learning network activities that follow the initial engagement in the boundary crossing ToT course. Th is leads, over time, to transformative value which is important in achieving the overall objective of such social learning, namely making knowledge more co-engaging, accessible and useful in the context where improved food security via better use of rainwater harvesting and conservation amongst smallholder farmers and household food producers is a necessary form of sustainable development. Orientation value, and enabling value were found to be vital for the emergence of other kinds of value. The evaluation model also allows for the lifting out of strategic value which points to wider uptake potential. All this creates the possibility for indicator development that can help inform iterative development of boundary crossing VET courses used to stimulate the co-construction of learning networks and ongoing social learning for sustainable development.
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  • Date Issued: 2023

Understanding foraging practices in Lagos metropolis to redesign urban greenspaces in support of human-nature interactions

  • Authors: Adeyemi, Opeyemi , Shackleton, Charlie M
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/401353 , vital:69728 , xlink:href="https://doi.org/10.1016/j.ufug.2022.127805"
  • Description: Enhancing knowledge of urban foraging across different urban landscapes is an urgent matter given that about two-thirds of the world’s population is projected to live in urban areas by 2050, whilst 50 % of Africa’s population is expected to live in cities by 2030. This study was conducted in Lagos metropolis which is the economic hub of Africa’s most populous country. Data was collected using an in-person, semi-structured questionnaire from 347 persons who were 18 years or older to identify foragers and non-foragers, their sociodemographic profiles, and their foraging practices. Results revealed that about two out of three persons sampled forage to some degree. The collection happened more in domestic gardens (34 %) and streets (27 %) than in other foraging sites (such as unused lands, institutional grounds and lakes and riparian fringes). A total of 35 species were reportedly foraged within the metropolis, mostly for food (71 %) and medicine (26 %). Mango (Mangifera indica), pawpaw (Carica papaya), tropical almond (Terminalia catappa), fish (various species), bitter leaf (Vernonia amygdalina) and spinach (Spinacia oleracea) were the most gathered species. The distance travelled to foraging wild species ranged from 5 m to 25 km. The primary motivation for foraging was the acquisition of fresh and natural materials. However, some felt that foraging was a stressful activity. The unavailability of foraging sites and species was the major constraint to foraging in this megacity. Hence, efforts to increase the edible components of public green spaces and to provide free access could potentially allow more people to forage and make current foraging more secure. We suggest that making provisions for foraging in urban planning goals could contribute to the sustainable development of cities in Africa and elsewhere.
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  • Date Issued: 2023

Using Facebook user photos to quantify surface water dependency in Southern African arid-zone bird species

  • Authors: Dixon, Elizabeth A , Smit, Ben
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/441668 , vital:73905 , https://doi.org/10.1080/01584197.2023.2182223
  • Description: Birds need to maintain their hydration by either gaining water from their food or by drinking surface water. Many arid-zone birds do not need to consume surface water to maintain body condition. Conservationists need to better understand avian use of surface water sources to inform management plans in a warming world. In this study, we explored the use of Facebook’s image search as a tool to predict interspecific variations in avian surface water use. There was a significant correlation between the proportion of Facebook photographs of each species associated with surface water, and surface water use indices for these species based on published field studies. These findings suggest that Facebook may be a useful source of data for determining the dependence of bird species on surface water. Future research could address the potential for Facebook and other social media platforms for answering a range of ecological questions relating to avian water dependency.
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  • Date Issued: 2023

Women farmers leading and co-learning in an agroecology movement at the intersections of gender and climate

  • Authors: Chanyau, Ludwig , Rosenberg, Eureta
  • Date: 2023
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/373873 , vital:66730 , xlink:href="https://doi.org/10.1080/10130950.2023.2239313"
  • Description: This study, carried out in the Eastern Cape Province of South Africa, was particularly interested in women farmers’ access to social learning spaces for expanding their knowledge about farming in the context of climate change. Small-scale women and peasant farmers face historical intersectional inequalities as a result of the colonial and apartheid past which has continued to disadvantage women in the present through exclusion, limited or no access to finance, insecure or no land tenure, little bargaining power and unequal access to water. The gender prejudices and unequal access to resources experienced by women is brought into sharp relief by climate change. The article provides a case study of an agroecology movement led by women farmers that promotes climate-appropriate, low-cost farming practices using community and home gardens. The practices are tried out and further developed by women farmers themselves, relying on agroecology-informed extension services, open dialogue and the support of communities of practice. Unlike traditional top-down approaches to farmer learning common in public extension services, extension officers in the movement participate in creating conditions for co-learning and co-construction of new knowledge − that is, social learning − thus responding directly to their needs as farmers. The lead researcher joined in and observed farming and learning activities following an ethnographic approach. Farmers and other movement members were engaged in semi-structured interviews which explored the value derived from social learning (Wenger-Trayner and Wenger-Trayner Citation2020). The article concludes that the movement is responding to many of the intersectional challenges that women farmers in the Eastern Cape face. Further, its social learning approach holds potential for expanding women farmers’ ability to provide for themselves and their communities and inform their climate change adaptation.
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  • Date Issued: 2023

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

Age and growth of the Cape knifejaw Oplegnathus conwayi, an endemic South African teleost

  • Authors: Foster, Ryan M , Childs, Amber-Robyn , Mann, Bruce Q , Potts, Warren M
  • Date: 2022
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/443128 , vital:74080 , https://doi.org/10.1080/15627020.2022.2035254
  • Description: The South African spearfishery targets a variety of data-deficient species, which are consequently poorly managed. This study aimed to describe the age and growth of one of these species, the Cape knifejaw, Oplegnathus conwayi, which is endemic to the southern and eastern coasts of South Africa. Monthly biological samples were collected through research spearfishing (n = 170) and augmented by recreational spearfishers’ catches (n = 135). The results indicated that the O. conwayi population sex ratio was skewed towards males (1M:0.6F). The length- and age-frequency distributions were similar between sexes. Oplegnathus conwayi is a relatively slow-growing species, with a maximum-recorded age of 27 years. No significant differences were observed between male and female growth, with the overall population growth curve being best described as L(t) = 697.15(1 − e−0.06(t−6.30)). The slow growth observed in this species is characteristic of a species that is vulnerable to overexploitation, and accordingly a precautionary approach to future management is recommended.
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  • 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
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