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Overview of Császár orders and quasi-uniformities on complete lattices
No full textIn this paper we introduce a theory of quasi-uniformities and syntopogenous structures on complete lattices, extending the results from [7] and [5] in a general categorical context. In particular, we show that topogenous orders on a complete lattice encompass both closure and interior operations, and that a syntopogenous structure is a base of a quasi-uniformity. In fact, not only does this paper extend various structures from category theory, but it also demonstrates that these constructs can be studied without relying on (E,M)-factorizations, which have historically been necessary for their study in a categorical setting. In closing, we show that any ⋀-structure of a complete lattice can be used to construct a base of transitive quasi-uniformity on the lattice. © 2025 Elsevier B.V
Factors affecting the adoption of online learning in South Africa using a systematic review
No full textSouth Africa’s Higher Education Institutions, traditionally reliant on face-to-face settings, demonstrated remarkable resilience and adaptability during the coronavirus outbreak. The swift response to the pandemic, including the shift to virtual classes following the lockdown announcement on 26 March 2020, is a testament to the sector's ability to overcome challenges. The most common difficulties cited among higher education institutions were the lack of infrastructure, inequalities amongst students and institutions, the digital divide, economic shortfalls, and social dynamics. The factors that hinder the adoption of online learning, such as facilitating conditions, computer efficacy, usefulness of online learning and adaptability, and social dynamics, can be explored further as the body of knowledge on these factors is limited. This study used a systematic review to determine the factors that affect the adoption of online learning in South Africa. The study used PRISMA guidelines to evaluate the academic articles published between 2019 and 2023. The PRISMA Guidelines is a trusted and credible method applied across the health and education sectors to ensure rigour and transparency, encourage replicability, and eliminate bias. The study retrieved articles from reputable databases such as Google Scholar, Springer, Scopus, etc. Clear inclusion/exclusion criteria and standardised methods were applied to minimise biases and identify relevant studies. Forty articles were reviewed systematically to determine the factors that affect the adoption of online learning in South African Higher Education Institutions (HEIs)
Biomolecular affinities and cytotoxicity of copper(I) and silver(I) phosphine–pyridinyl complexes against CACO-2 and CASKI cell lines
No full textA series of three copper (I) and three silver (I) complexes with the general formula [M L(PPh3)2]NO3, (M = Cu for complexes 1–3 and Ag for complexes 4–6) are synthesized by reacting copper(I) or silver(I)-nitrate and triphenylphosphine with the bidentate ligands, (E)-1-(pyridin-2-yl)-N-(o-tolyl)methanimine L1, (E)-N-isopropyl-1-(pyridine-2-yl)methanimine L2, or (E)-N-(2,6-dimethylphenyl)-1-(pyridine-2-yl)methanimine L3. The structures of these complexes are elucidated using a combination of NMR spectroscopy, FTIR, UV–visible, mass spectrometry, elemental analysis, and single-crystal X-ray diffraction. Structural analysis revealed that the Schiff bases coordinate to the metal centers in a bidentate fashion, with triphenylphosphine occupying the remaining coordination sites in complexes 1, 2, and 5. In contrast, in complexes 3, 4, and 6, one coordination site is occupied by a nitrate anion instead of triphenylphosphine. All six complexes exhibit a distorted tetrahedral geometry around the metal center, as confirmed by τ4 values ranging from 0.54 to 0.87. Binding studies with calf-thymus DNA demonstrated that complexes 1–6 interact via intercalation, with complex 5 exhibiting the highest binding constant. Furthermore, all complexes showed strong binding affinity toward bovine serum albumin. Cytotoxicity studies revealed significant cytotoxicity of complexes 1–6 against human colon adenocarcinoma (Caco-2) and human cervical epidermoid carcinoma (Caski) cell lines
Seasonal variations in water use of japanese plum orchards under micro-sprinkler and drip irrigation methods using fruitlook data
No full textSouth Africa is considered one of the driest countries, and its water insecurity challenges are exacerbated by climate change and variability, depletion, and degradation, among other factors. The challenges of water insecurity are exacerbated by some of the introduced crops, like the Japanese plums (Prunus salicina Lindl.) grown in South Africa, as they consume a lot of water. The Japanese plums are grown under irrigation to supplement low and erratic rainfall in the country. There is little information on the water requirements of Japanese plums (particularly in water-scarce regions), a gap addressed by this study. Therefore, the study aims to quantify and compare the seasonal water use of high-performing, full-bearing Japanese plum orchards under drip and micro-sprinkler irrigation in the Western Cape Province, using readily available satellite data from the FruitLook platform. The seasonal water use volumes of selected plum orchards were compared at provincial and farm scales. At a provincial scale, micro-sprinkler-irrigated orchards consumed significantly more water (up to 19%) than drip-irrigated orchards, whilst drip-irrigated orchards experienced an average 38% greater water deficit. Results were more variable at the farm scale, which was attributed to the influence of site-specific soil, climate, and crop conditions on the performance of the irrigation methods. Therefore, a blanket approach cannot be used when selecting an irrigation method and design. Instead, a case-by-case approach is recommended, which takes into account the root distribution, soil texture, and planting density, among other factors. The generated knowledge facilitates allocating and licensing water resources, developing accurate irrigation scheduling, and promoting improved water use efficiency
The use of pre-sentence reports in the deterrence of drug-related gang activity in South Africa
No full textThere are several outside influences that impact the criminal conduct of an offender. Pre-sentence reports must be used where the offender is to be properly and effectively rehabilitated, this is a key consideration. The only way to successfully implement rehabilitative measures is to examine all the circumstances that led to the crime. This paper is centred on the judiciary’s potential to take action and compel the use of pre- sentence reports not only as a deterrent to gang activity but also as a method of upholding the principles of sentencing. It is challenging to disregard the potential impact pre-sentence reports may have on the offender and the community they are endangering. There will be a further discussion as to what the legal system and specifically the judiciary can do, to stop gang violence and the ingrained “an eye for an eye” maxim. Psychological and societal factors influence the urge for survival in South African gang activity. The responsibility of the judiciary to reduce the offenders’ capacity and need for using violence to establish dominance and power over their communities, will be explored. By denying the significance and influence of pre-sentence reports, one is merely supporting the idea that prisons are training grounds for criminals. A pre-sentence report’s possible preventative authority will be discussed. This issue extends beyond the convicts’ rehabilitation since it also involves the need for retribution for those who suffer in gang-infested regions. The question to be answered is whether the pre-sentence reports are being used effectively
Exploring the barriers to optimal implementation of monitoring and evaluation of school oral health programmes amongst oral health professionals, within a Sub-District of the Cape Metropole
No full textDental caries is a major Public Health concern among school children worldwide, with a prevalence of 90% in South Africa. Untreated caries can result in pain, infection, and absenteeism, adversely affecting academic performance in school children. In response, South African education and health departments have implemented comprehensive policies for oral health prevention. Although Public Oral Hygienists are essential in providing oral health preventative services, the effectiveness of these programmes are often diminished by insufficient Monitoring and Evaluation (M&E) both globally and in South Africa. Aim This research study aimed to explore barriers which hinder the optimal implementation of Monitoring and Evaluation of School Oral Health Programmes amongst Oral Health Professionals, within a Sub-District of the Cape Metropole
Impact of wastewater treatment works discharges on surface water quality in Emalahleni Local Municipality, Mpumalanga Province
No full textThis thesis reports the research work undertaken to evaluate the effects of Wastewater Treatment Works discharges on surface water quality in Emalahleni Local Municipality (ELM), Mpumalanga Province. Ferrobank and Riverview Wastewater Treatment Works (WWTWs) were identified for the research study. The study concentrated on assessing surface water quality by identifying the impact differences in water quality at the upstream and downstream sites of each WWTW effluent discharge point. The following physio-chemical and microbial water quality parameters (temperature, pH, turbidity, electrical conductivity, dissolved oxygen, phosphate, ammonia, nitrate, chemical oxygen demand, total suspended solids and Escherichia coli) were assessed. The water quality results were compared to the water use licence conditions for Ferrobank WWTW and the general limit values applicable to wastewater discharge into a water resource for Riverview WWTW respectively. The impact of these WWTWs was also assessed on the groundwater through one identified private borehole located within the vicinity of each WWTW mainly to identify any potential risk to the hydrogeological environment of the study area
Sensitive gold nanostar-based adsorption sensor for the determination of dexamethasone
No full textHerein, a novel, highly efficient electrochemical adsorption method is introduced for detection of the potent anti-inflammatory synthetic corticosteroid, dexamethasone (DEX). Unlike conventional electrochemical techniques that rely on high reduction potentials, the proposed sensor offers an alternative adsorption-based mechanism with a gold nanostar-modified glassy carbon electrode (AuNS|GCE). This enables DEX detection at a less negative or moderate reduction potential of +200 mV, circumventing potential window limitations of a GCE and providing a suitable microenvironment for detection in biological media. DEX is known to effectively prevent or suppress symptoms of inflammation due to its small applied dosage; however, an overdose thereof in the human body could lead to adverse drug effects such as gastrointestinal perforation, seizures, and heart attacks. Therefore, a sensitive method is essential to monitor DEX concentration in biofluids such as urine. NMGA-capped AuNSs were leveraged to enhance the active surface area of the sensing platform and allow adsorption of DEX onto the gold surfaces through its highly electronegative fluorine atom. Under optimized experimental conditions, the developed AuNS|GCE sensor showed excellent analytical performance with a remarkably low limit of detection (LOD) of 1.11 nM, a good sensitivity of 0.187 µA.nM−1, and a high percentage recovery of 92.5% over the dynamic linear range of 20–120 nM (linear regression of 0.995). The favourable electrochemical performance of this sensor allowed for successful application in the sensitive determination of DEX in synthetic urine (20% v/v in PBS, pH 7)
Metal-organic frameworks and their derivatives as catalysts of magnesium hydrogenation
No full textThis article presents the results of an experimental study on the preparation and characterisation of metal-organic frameworks (MOFs) formed by coordination polymers of Ni(II) and Co(II) itaconates (Ni-IA and Co-IA), as well as the products of thermolysis of their mixtures. It is found that the thermolysis results in the formation of heterometallic CoNi nanoparticles enveloped in a porous carbonaceous matrix (CoNi@C core-shell structures). The catalytic effect of the as-synthesised MOFs and their CoNi@C derivatives on the hydrogenation of Mg during high-energy reactive ball milling (HRBM) in hydrogen has been studied. These catalysts were shown to increase the rate of hydrogenation of Mg during HRBM by about ninefold as compared with non-catalysed magnesium. The kinetic improvements are superior to those observed earlier for other catalysts, including Pd-doped UiO-66 MOF and Ni nanoparticles deposited onto graphene-like materials. At the same time, the achieved reacted fractions when using MOFs and their derivatives as catalysts for magnesium hydrogenation were incomplete. It was found that the use of the as-synthesised MOFs as additives to Mg during HRBM results in the slow hydrogenation of pristine magnesium at room temperature during pauses between the first milling sessions. Almost full conversion of Mg into MgH2 was achieved when the milling vial was kept during these pauses until pressure stabilisation. Based on this observation, it was assumed that the intermediate products of MOF decomposition are more active catalysts of magnesium hydrogenation than the CoNi@C core-shell structures formed as the final MOF decomposition product
A critical view of applying life cycle assessment on disposable diapers in a rural context
No full textThe environmental impacts of disposable diapers in comparison to reusable diapers have been a matter of interest within the life cycle assessment (LCA) community for many years. However, the majority of LCAs have been conducted in developed countries with well-developed waste management infrastructure. This study takes a critical view of the application of LCA to evaluate the environmental impacts of disposable diapers in rural areas. In the study area, the majority of diapers were openly dumped (43.8%), sent to unsanitary landfills (26.1%) or burned (18.6%). The production phase contributed the most to the majority of impact categories, excluding freshwater exotoxicity, marine exotoxicity and human carcinogenic toxicity. These impacts were instead dominated by end-of-life impacts and also had the highest relative significance when normalisation was conducted. The lack of and/or poor waste management has resulted in the end of life of diapers being a significant environmental risk. However, current life cycle impact methodologies are not able to fully cover the scope of impacts presented by mismanaged diaper waste. This study demonstrates the importance of geographical contexts when conducting diaper LCAs wherein, in some scenarios, it may be necessary to include impacts beyond the scope of a traditional LCA. significance: • This is the first LCA conducted on diapers in the rural context of Africa. • The majority of impacts were attributed to the production of disposable diapers. • The majority of disposable diapers were dumped or sent to unsanitary landfills