UWCScholar
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Measurement of radon exhalation and emanation in synthesized coal fly ash-based geopolymer paste for building applications
(Elsevier B.V., 2025) Ntsa, Evral; Lindsay, Robert; Mouele, Emile Salomon Massima; Mukaba, Jean Luc; Petrik, Leslie Felicia
This study examines the radon exhalation potential of CFA and CFA-based GPP products, focusing on their elemental composition, structural properties, and radon containment capabilities. The particle size analysis result revealed that a substantial portion of CFA particles are fine, contributing to a greater surface area, which increased the potential for radon emanation. SEM analysis highlighted microstructural differences, with denser structures in the geopolymer products. XRF result revealed reductions in potassium (⁴⁰K), uranium (²³⁵U, ²³⁸U), and thorium (²²⁶Ra) progenitors in CFA-based GPP products compared to CFA, and resulted in lower radioactivity due to the dilution effect of fillers and additives. XRD analysis showed the presence of crystalline phases such as quartz, mullite and amorphous phases in CFA and in the CFA-based GPP. The amorphous glassy phase in CFA, being rich in SiO₂ and Al₂O₃ precursors was critical for forming the aluminosilicate geopolymer network, that reduced porosity and trapped radon progenitors. Variations in CaO content and the formation of Ca containing mineral phases enhanced radon retention in CFA-base GPP products. Density measurements indicated that higher-density products exhibited lower permeability, reducing radon exhalation. Radioactivity measurements showed that CFA emitted 684 Bq/kg, above the world average of 420 Bq/kg and CFA-based GPP emitted between 408 and 459 Bq/kg. These findings underscored the need for controlling formulations and curing conditions to mitigate radon emanations of CFA-based products such as geopolymers.
Emotional social screening tool for school readiness – revised: isiXhosa adaptation
(African Online Scientific Information Systems Pty Ltd, 2025) Munnik, Erica; Reddi, Prenita; Smith, Mario R.
Background: The need for the adaptation of instruments to other native languages to promote culture-fairness framed this study. Aim: This article reports on the adaptation of the locally developed Emotional Social Screening Tool for School Readiness (E3SR-R) into isiXhosa. Setting: This adaptation study was conducted in South Africa. Methods: The study was executed in five steps based on the Sousa and Rajjanasrirat model. The quality of the processes for translation and establishing linguistic equivalence were evaluated using the Quality of Translation and Linguistic Equivalence Checklist (QTLC). Results: A high level of inter-rater agreement was reported. A high level of compliance with International Test Commission (ITC) guidelines for translation and linguistic equivalence was achieved. An expert reviewer (ER) concluded that the isiXhosa version of the E3SR-R demonstrated content validity. Conclusion: The E3SR-R English version was successfully adapted to isiXhosa. Contribution: The resultant isiXhosa translation extends the availability and utility of the E3SR-R to isiXhosa speakers.
Inactivation of cyclotella meneghiniana to prepare biochar by in-liquid pulsed discharge plasma
(Elsevier Ltd, 2025) Massima Mouele, Emile Salomon; Petrik, Leslie Felicia; Bladergroen, Bernard Jan
The large-scale outbreaks of harmful algal blooms continue to impact river and lake ecosystems. Converting harmful algal blooms into algal biochar presents a novel approach. This work investigates the inactivation of Cyclotella meneghiniana (the dominant species in diatom blooms) to prepare biochar by in-liquid pulsed discharge plasma (LPDP). Under the conditions of a peak voltage of 30 kV and an electrode spacing of 7 mm, a 100 % inactivation ratio can be achieved within 20 min plasma treatment. The multiple physical and chemical effects generated by in-liquid pulsed discharge cause the cell structure destruction, chlorophyll-a content reduction, enzyme activity decrease, and malondialdehyde oxidative degradation leading to algal inactivation and biochar production. The obtained algal biochar has the advantages of a rich carbon content and a stable structure. This work provides a new technological option for resource utilization of algal blooms.
Alcohol use in first responders in South Africa: psychological distress factors related to harmful drinking and alcohol dependence
(AVES, 2025) Padmanabhanunni, Anita; Pretorius, Tyrone Brian
First responders are frequently exposed to traumatic events and highly stressful situations due to the nature of their work. This enhances their vulnerability to psychological distress and the use of maladaptive strategies to cope. In South Africa, few studies have explored the relationship between alcohol use and mental health indicators among first responders. This study investigated the association between harmful drinking behaviors and post-traumatic stress disorder, depression, anxiety, emotional exhaustion, depersonalization, fatigue, and insomnia. A cross-sectional study was conducted with 429 first responders. The participants completed the Alcohol Use Identification Test, Patient Health Questionnaire-9, Generalized Anxiety Disorder Scale-7, Post-traumatic Stress Disorder Checklist for DSM-5, Maslach Burnout Inventory, Life Events Checklist, Chalder Fatigue Questionnaire, and Insomnia Severity Index. Higher levels of alcohol use were associated with higher levels of psychological distress. Specifically, anxiety, depersonalization, fatigue, and insomnia emerged as significant predictors of alcohol consumption. Participants classified as at risk for harmful alcohol use reported higher levels of psychological distress than those not at risk. Additionally, participants identified as having alcohol dependence reported higher levels of distress across all indicators than did those without alcohol dependence. These results underscore the need for integrated interventions that address both psychological distress and harmful drinking behaviors.
Balancing yields and sustainability: an eco-friendly approach to losartan synthesis using green palladium nanoparticles
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Antunes, Edith M.; Adegoke, Yusuf Adeyemi; Mgwigwi, Sinazo; Malan, Sarel F.; Beukes, Denzil R.
This study presents a sustainable, environmentally friendly synthetic route for the production of key intermediates in losartan using palladium nanoparticles (PdNPs) derived from a brown seaweed, Sargassum incisifolium, as a recyclable nanocatalyst. A key intermediate, biaryl, was synthesized with an excellent yield (98%) via Suzuki–Miyaura coupling between 2-bromobenzonitrile and 4-methylphenylboronic acid, catalyzed using bio-derived PdNPs under mild conditions. Subsequent bromination using N-bromosuccinimide (NBS) under LED light, followed by imidazole coupling and tetrazole ring formation, allowed for the production of losartan with an overall yield of 27%. The PdNP catalyst exhibited high stability and recyclability, as well as strong catalytic activity, even at lower loadings, and nitrosamine formation was not detected. While the overall yield was lower than that of traditional industrial methods, this was due to the deliberate avoidance of the use of toxic reagents, hazardous solvents, and protection/deprotection steps commonly used in conventional routes. This trade-off marks a shift in pharmaceutical process development, where environmental and safety considerations are increasingly prioritized in line with green chemistry and regulatory frameworks. This study provides a foundation for green scaling up strategies, incorporating sustainability principles into drug synthesis.