Research Articles (University of Pretoria)

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This collection offers open access to the full text of research articles published by staff, students and affiliates of the University of Pretoria. These items are identical in content to their published counterparts. It is linked to the Research Information System and complements the Annual Research Report.

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Cash flow risk management across multiple construction projects using value at risk
Didar, Ensiyeh; Bazargan, Amirhossein; Bagherpour, Morteza (Emerald, 2026)
PURPOSE : Managing cash flow risk across multiple concurrent construction projects presents significant challenges due to inherent uncertainties and complexities, which can jeopardize a company’s financial stability and project success. This research aims to develop a robust and reliable model for effective cash flow prediction and risk management in the construction industry. DESIGN/METHODOLOGY/APPROACH : We propose a novel framework that integrates value at risk (VaR) with simulation-based optimization techniques to quantify and manage the impact of various financial risks on cash flow across multiple projects. This robust predictive method combines theoretical and practical approaches, advancing existing cash flow management practices in construction project management and finance. FINDINGS : The study demonstrates that traditional cash flow management methods often fail to account for the cumulative risks in multi-project environments. Our approach effectively mitigates the adverse effects of financial volatility by providing a probabilistic assessment of potential losses, ensuring alignment of cash flows with established baselines and thereby improving project outcomes and financial resilience. ORIGINALITY/VALUE : This research makes a significant contribution by introducing an innovative method that applies VaR to construction cash flow management for multiple concurrent projects – a novel application in this context. By addressing the major difficulties of quantifying and managing financial risks in complex project portfolios, our approach offers new insights and practical tools for enhancing financial planning, risk management and overall resilience in the construction industry.
Conditions of project knowledge transfer events: a qualitative exploration of configurations
Van Waveren, Cornelis Cristo; Oerlemans, Leon A.G.; Pretorius, Marthinus W. (Emerald, 2026-12)
PURPOSE : Transferring project knowledge is challenging due to the temporary nature and the intense focus on deliverables and milestones. Existing transfer models often overlook the various conditions for project knowledge transfer and the configurations of conditions that shape these transfer events. This exploratory study seeks to deepen understanding of these conditions and their configurations. To achieve this, we address the following research questions: which conditions influence project knowledge transfer and which configurations of conditions can be observed in project knowledge transfer events? DESIGN/METHODOLOGY/APPROACH : A literature review revealed a lack of systematic theoretical and empirical knowledge regarding specific conditions and configurations that affect project knowledge transfer events. To address this gap, 20 project knowledge-sharing events were examined using an exploratory, qualitative research design. FINDINGS : A range of conditions for project knowledge transfer could be identified, which were grouped into three clusters: characteristics of the relationship between the actors involved in project knowledge transfer, tools and techniques and facilitators such as co-location. By applying the principle of equifinality, three configurations of conditions emerged: a formalistic, authoritative and interactive configuration of conditions of knowledge transfer events. ORIGINALITY/VALUE : This paper contributes to advancing a configurational approach to project-related knowledge transfer. Such a holistic perspective helps researchers and practitioners understand how different elements interact to produce outcomes. It is particularly valuable in complex, real-world contexts, such as project-based knowledge transfer.
Oxygen-bridged electronic coupling of Ir single-atom sites for durable acidic oxygen evolution reaction
Xiang, Yijun; Wang, Hui; Li, Shaoxiong; Li, Linlin; Ren, Jianwei; Xing, Gengyu; Deng, Liming; Peng, Shengjie (Royal Society of Chemistry, 2026)
Please read abstract in the article.
Synergistic VO and VN dual vacancies in homometallic Co3O4/CoN heterojunction boosting built-in electric field for efficient hydrogen production
Feng, Yufa; Tian, Jingjing; Shao, Youxiang; Dyosiba, Xoliswa Lindokuhle; Ren, Jianwei; Xiong, Jiageng; Gao, Qingsheng; Li, Hao (Elsevier, 2026-02)
Please read abstract in the article.
DNA barcoding and anti-tyrosinase activities of three species-representative populations of the genus Greyia Hook & Harv
Botha, Ine; De Canha, Marco Nuno; Oberlander, Kenneth Carl; Botes, Jana; Lall, Namrita; Berger, David Kenneth (Elsevier, 2026-02)
The tree genus Greyia is endemic to South Africa and Eswatini. The Eastern Cape species Greyia flanaganii Bolus is confined to a limited range west of the Kei River. Greyia radlkoferi Szyszyl. occurs in Limpopo Province, whereas Greyia sutherlandii Hook. & Harv. is associated with KwaZulu-Natal Province, but the ranges of these two species overlap in Mpumalanga Province. Greyia trees are of value to the bioeconomy as leaf extracts from G. flanaganii and G. radlkoferi possess anti-tyrosinase activity and low toxicity and are being developed in herbal formulations for the treatment of skin hyper-pigmentation. The main active compound is 2’,4’,6’ trihydroxydihydrochalcone. However, there are no reports of medicinal assays from Greyia trees growing in their natural habitat, it is not known whether the third species - G. sutherlandii - has activity, and DNA barcode data is limited. To address these knowledge gaps, we sampled five trees per Greyia species that matched morphological descriptions and were from sites close to type specimen collection records. Leaf ethanolic extracts from G. sutherlandii had similar average anti-tyrosinase activity (IC50 = 84 µg/mL ± 18 [SD]) when compared to G. radlkoferi (58 µg/mL ± 21) and G. flanaganii (72 µg/mL ± 11). High Performance Thin Layer Chromatography showed the presence of the active compound in all three species, although it was below the detection limit of 4.4 µg/10 mg extract in two of the G. flanaganii samples. Considering the difficulty in differentiating G. sutherlandii from G. radlkoferi morphologically in the field and production orchards, we investigated DNA barcoding as a method of species-specific authentication. Phylogenetic analysis using Bayesian Inference from combined ITS, trnL-F, matK and psbA-trnH barcodes from the 15 Greyia trees plus Genbank sequences indicated (i) clear differentiation from other lineages in the order Geraniales, but (ii) extremely short internal branches within Greyia and poor discrimination between Greyia species and individuals. Our study has shown that natural populations of all three species sampled in late summer exhibit consistent leaf anti-tyrosinase activity between biological replicate trees. We have demonstrated activity from G. sutherlandii for the first time, indicating that this species can also be deployed in production orchards. However, alternative phylogenetically informative SNP markers need to be developed to provide species-specific authentication of Greyia extracts in herbal products. HIGHLIGHTS • First report of anti-tyrosinase activity of leaf extracts from wild-growing Greyia spp. • Greyia sutherlandii leaf extracts shown to have anti-tyrosinase activity for the first time. • HPTLC method developed to quantify the active compound 2′,4′,6′-trihydroxydihydrochalcone. • DNA barcoding (ITS, matK, trnL-F, psbA-trnH) conducted on core populations of three Greyia spp. • DNA barcode phyogeny discriminates Greyia spp. from other Geraniales genera. • G.sutherlandii and G.radlkoferi not resolved phylogenetically with DNA barcodes. • G. sutherlandii and G. radlkoferi hard to differentiate in the field morphologically.
Adsorptive removal of Carbamazepine from synthetic wastewater using Moringa oleifera seed coat
Azeh, Peace S.; Jimoh, Monsurat Omolola; Masitha, Mabafokeng; Iwarere, Samuel Ayodele; Daramola, Michael Olawale (Elsevier, 2026-01)
Biosorption has demonstrated effectiveness in eliminating contaminants of emerging concern (CECs) that lack inclusion in current water quality standards. These pollutants impede progress towards UN Sustainable Development Goals 6 and 14, pertaining to clean water accessibility and marine life preservation. This research investigated the adsorption potential of the persistent pharmaceutical pollutant, carbamazepine, using Moringa oleifera (MO) seed coat. This research investigated the adsorption potential of the persistent pharmaceutical pollutant, carbamazepine, using MO seed coat biochar. Acid hydrolysis and subsequent carbonization produced a biochar with superior properties for adsorption as confirmed by FTIR, SEM, EDX, CHNOS, and XRD analyses. The influence of agitation speed (200 rpm, 300 rpm, and 400 rpm), adsorption duration (0 to 180 min), and adsorption temperature (30 °C, 40 °C, and 50 °C) on CBZ removal in synthetic wastewater were studied. The quadratic regression model obtained from Box Behnken experimental design (BBD) with Response surface methodology (RSM) showed a strong predictive ability with R² = 0.9754 and adjusted-R² = 0.9015. Agitation speed significantly influenced the adsorption capacity as evidenced by a p-value of 0.02848. The optimum conditions for CBZ adsorption were 400 rpm, 30 °C, and 2.15 h at which a maximum adsorption capacity of 51.87 mg/g was anticipated. The adsorption behaviour was best described by pseudo-second order kinetics and the Temkin isotherm model. The study confirmed that MO seed coat biochar as a promising green adsorbent for pharmaceutical contaminant removal in wastewater treatment. HIGHLIGHTS • Adsorption of carbamazepine (CBZ) by Moringa Oleifera seed coat biochar is presented. • Acid hydrolysis with 85 % H3PO4 followed by carbonisation increased the surface area from 1.160 m2/g in the raw biosorbent to 237.3 m2/g in the biochar. • 93.3 % of CBZ was removed from 50 ppm solution within 3 hours of agitation at 200 rpm. • Agitation speed significantly affected adsorption capacity for CBZ unlike adsorption temeprature and time • Pseudo second-order kinetics and Temkin isotherm model adequately described the adsorption of CBZ on MO.
Uncovering cultural regularities underpinning the pedagogy of learners with disabilities
Kumador, David Kwame; Muthivhi, Azwihangwisi Edward (AOSIS, 2026-01)
BACKGROUND : Fear of disability tends to influence teachers’ pedagogical practices in early childhood education in Ghana. Deeply rooted in socio-cultural beliefs, this fear hinders inclusive education and perpetuates exclusionary practices. AIM : This article explores the fear of disability within Ghanaian early childhood education, as an instance of Ghanaian and West African cultural practices manifesting in and through teachers’ classroom activities, which constrain the effective learning and development of learners with disabilities. Setting: The research was conducted with teachers from seven early childhood education centres in Accra, Ghana. METHOD : We applied focus group interviews, integrating a local conversational approach to enhance the effectiveness of our Vygotsky-inspired authentic questioning method. Using an approach that embodies respect, mutual acknowledgement, and affirmation of each other’s humanity, the first author was able to uncover the profound cultural meanings of the teachers’ practices, which would otherwise have been difficult to reveal through a rigid application of formal methods. RESULTS : The findings promote cultural contingency of methods as tools for uncovering the dynamic structure of cultural processes, such as fear of disability, that underpin complex social practices of the pedagogy of learners with disabilities. CONCLUSION : The article provides an analysis of the data and the process through which data was produced, leading to the uncovering of the underlying culturally situated regulatory processes vis-à-vis the teachers’ relationship with learners with disabilities. CONTRIBUTION : The paper contributes to the application of informal methods of inquiry, informed by both theory and practice in cultural psychology and education.
Identification of multiple cardiotonic steroids in faecal material of untreated humans and rat strains
Masso, Zelie Flavienne; Mullah, Ebrahim; Bint, Hannah; Thiba, Anza; Dinat, Sarhana; Nweke, Ekene Emmanuel; Norton, Gavin R.; Woodiwiss, Angela Jill; Cromarty, Allan Duncan; Candy, Geoffrey Patrick (Elsevier, 2026-03)
Endogenous cardiotonic steroid (CTS) concentrations are raised in cardiovascular diseases. CTSs undergo gastro-hepatobiliary recirculation, with the gut being an important route of elimination, yet the presence of CTSs in faecal material is seldom reported. This study investigated methods to extract and identify the presence of CTSs in faecal material of rats and humans without prior treatment. METHODS : Freeze-dried faecal material from different untreated rat strains was extracted using various solvents, with separation and identification of CTSs using HPLC/MS. Preliminary results were obtained from human faecal material. RESULTS : Multiple CTSs were identified in faecal material, with marinobufagenin (MBG) predominant. Telocinobufagin was only detected in certain rat strains, whereas the extraction methods used did not recover ouabain. MBG and digoxin were elevated in Dahl salt sensitive rats fed supplementary salt. Bufalin was present in most spontaneously hypertensive rats (SHRs) but was not detectable in Wistar Kyoto rats (WKY). Conversely, digitoxin was detected in most WKYs but only few SHRs. Levels of digitoxin and bufalin remained relatively constant over 24 days in untreated rats. Solvent selection was critical in determining the CTSs extracted from human faecal material. CONCLUSIONS : Multiple CTSs were detected in faecal material of untreated rats and humans. Steroids varied between rat strains and aligned with phenotype. Extraction requires further solvent optimisation and the use of tandem MS/MS is essential to reliably detect the profile of CTSs present. Analysis of CTSs present in readily available faecal material will enable studies to determine relationships between CTSs, the microbiome and disease progression. HIGHLIGHTS • Extraction of cardiotonic steroids from faecal material is critically dependent on the solvent. • Multiple cardiotonic steroids were identified in the faecal material of untreated rats and humans. • Steroids varied with rat strains with marinobufagin being most abundant. • Bufalin and digitoxin were predominant in SHR and WKY rat faeces respectively. • Identified steroids isolated aligned with the phenotype of the rat strain.
Ultrastructural features of the excurrent ducts of the testis of a wild bird, the cattle egret (Bubulcus ibis)
Roopnarine, Narindra H.; Aire, Tom A.; Lensink, Antoinette V,; Gupta, Sunil K.; Hopkins, Curtis E.; Charles, Matthew B. (Elsevier, 2026-06)
The structure and functions of components of the excurrent ducts of the testis of birds are still poorly understood. Most of the few reports on these ducts are on domesticated avian species. This report on the cattle egret is one of the very few studies on wild birds. Tissues from the ducts of five sexually mature and active male birds were routinely prepared and stained for light and transmission electron microscopy. The epididymis and ductus deferens of the cattle egret are generally similar structurally to those reported for domestic birds, with a number of cellular differences. The epithelium of certain segments of the egret’s rete testis displayed numerous, large intercellular spaces, not usually observed in most domestic avian species. As in the domestic species of birds, the proximal efferent ducts in the cattle egret displayed a robust endocytic apparatus as well as abundant lysosomes, but there were very few heterolysosomes and telolysosomes, which were common in domestic species. The border between the proximal and distal efferent ducts also demonstrated active spermiophagy. In addition to evidence of moderate secretary activities, the presence of extremely large heterolysosomes and telolysosomes also demonstrated the endocytic and digestive ability of cells lining the ductus deferens. HIGHLIGHTS • Dilated intercellular spaces in the rete epithelium. • Considerable spermiophagy at the junction between the proximal and distal efferent ducts • Numerous coupling organelles involved in the desmosome-mitochondria complexes (DMC) as well as in the (endoplasmic reticulum (ER)–mitochondria encounter structure (ERMES) in the epididymis and ductus deferens. • Dense bodies (lysosomes), heterolysosomes as well as telolysosomes abound in the proximal efferent duct, indicating considerable endocytic and phagocytic activities of luminal materials.
Biofiltration, seasonality, and distribution system factors influence nitrifier communities in a full-scale chloraminated drinking water system
Potgieter, Sarah; Oosthuizen-Vosloo, Solize; Langenfeld, Kathryn; Dowdell, Katherine S.; Vedrin, Matthew; Lahr, Rebecca; Pinto, Ameet J.; Raskin, Lutgarde (Elsevier, 2026-03)
Nitrification in chloraminated drinking water systems has been widely studied, although limited information is available on the role of biofiltration in shaping the nitrifier communities within drinking water distribution systems (DWDS). Additionally, the co-occurrence of comammox and canonical nitrifiers in drinking water systems remains unclear. This study investigates how biofiltration shapes nitrifier communities in a full-scale drinking water system where chloramine is a secondary disinfectant, and biofilters are backwashed with chloraminated water. Samples were collected monthly for one year from biofilter effluent, finished water, and three DWDS sites with varying water ages, water quality, and nitrite concentrations. Nitrifier abundances were quantified using droplet digital PCR, which showed contrasting temporal trends between the ammonia-oxidizing bacteria amoA gene and both nitrite-oxidizing bacteria 16S rRNA gene and comammox amoB gene abundances. Genome-resolved quantitative metagenomics revealed Nitrosomonas cluster 6a species, canonical Nitrospira species, and Nitrospira-like comammox species as the dominant nitrifiers. The same populations were detected in biofilter effluent and across DWDS sites, indicating that biofilter operation contributed to the persistence of nitrifiers in the DWDS. Further, DWDS site-specific factors, such as water age and disinfectant degradation, influenced the presence and abundance of individual nitrifier populations. These findings advance our understanding of how upstream treatment processes influence microbial community structure and nitrifier persistence in full-scale chloraminated DWDSs, and highlight the importance of considering biofilter operation, alongside disinfection practices, within integrated nitrification control strategies. HIGHLIGHTS • Seasonal and spatial factors shaped nitrifier dynamics and nitrite accumulation. • Nitrosomonas cluster 6a, Nitrospira, and comammox co-occurred throughout the system. • Nitrifier MAGs in the biofilter effluent persisted through the distribution system. • Distribution system water age influenced the spatial patterns of Nitrosomonas MAGs. • Comammox showed seasonal variation and persisted post-chloramination.
Eczema : etiology, subtypes, therapeutic approaches and socioeconomic impact
Cuyler, Marize; Twilley, Danielle; Lall, Namrita (Frontiers Media, 2026-01)
Eczema is an inflammatory skin condition that affects individuals of all ages worldwide. Patients may develop various forms of eczema, including atopic dermatitis, contact dermatitis, which is often associated with an allergic response to various stimuli, dyshidrotic eczema which develops on the palms and soles, asteatotic dermatitis that predominantly occurs in elderly patients, nummular eczema characterized by its cylindrical shape lesions and seborrheic dermatitis often located on patient's scalps, back, face and chest. Extensive studies have been conducted on atopic dermatitis, however, limited information such as their etiology, effect on the immune system and potential treatments are available on the other types of eczema. The socioeconomic impacts of eczema include the cost of conventional treatments such as corticosteroids, immunosuppressive agents and phototherapy, expenses related to specialists’ consultation and the effect on work and school productivity. The impact of atopic dermatitis on patients’ quality of life, social functioning and individual healthcare expenses has been extensively studied in other countries but remains underreported in South Africa. Reports have estimated the annual direct and indirect costs in Australia, the United Kingdom and the United States, however reports are limited for South Africa. This study aimed to provide information on the different types of eczema's etiology, their respective socioeconomic impact in South Africa in correlation to the above mentioned inflated yearly cost, and conventional, targeted and alternative treatments commercially available. Several knowledge gaps were identified in this study, including the limited availability of information on asteatotic dermatitis, dyshidrotic dermatitis and nummular eczema, the effect most commercially available treatments have on other eczema subtypes and an in-depth review of the socioeconomic impact of eczema within the African continent.
Aphasia telepractice in action : insights and opportunities from Malaysian speech-language pathologists
Onwi, Nadwah; Romli, Muhammad Hibatullah; Singh, Susheel Kaur Dhillon Joginder; Salim, Mazatulfazura Sf; Dada, Shakila; Nazan, Ahmad Iqmer Nashriq Mohd (Routledge, 2026)
BACKGROUND : Telepractice leverages telecommunications technologies to deliver rehabilitation services remotely, offering increased accessibility and flexibility for patients. For individuals with aphasia, it represents as a valuable alternative to conventional in-person therapy, particularly for those facing geographical, mobility, or logistical barriers. As this service model gains global traction, understanding its implementation within specific cultural and healthcare contexts is essential. AIM : This study aimed to explore the practices and experiences of Malaysian speech-language pathologists (SLPs) in delivering telepractice services to individuals with aphasia. METHODS : Semi-structured interviews were conducted with six practicing SLPs from a rehabilitation hospital in Malaysia. The interviews were transcribed verbatim and analyzed using an inductive thematic analysis to identify key themes. RESULTS : Six female therapists (M = 33.83 years, SD = 7.47, range = 29 to 45), all of whom held degrees in the field of speech-language pathology from two local universities and had an average of 10 years of clinical experience, participated in the study. Two major themes emerged: (1) current practices in aphasia telepractice; and (2) systemic and practice-level barriers. A hybrid aphasia therapy model was reported to be use in this facility, allowing individuals to choose between in-person and telepractice sessions. Several challenges were identified, including limited culturally relevant digital resources, insufficient technical support, and unstable internet connectivity. CONCLUSIONS : This study highlights the adaptability and dedication of Malaysian SLPs in delivering telepractice services for aphasia despite notable systemic and technological barriers. Addressing these challenges offers a critical opportunity to enhance service delivery and accessibility of speech-language pathology services for individuals with aphasia.
Electrical characterization of sputter-induced deep levels in GaN thin films synthesized by electrodeposition
Ali, Abdulraoof Idriss Ahmed; Taghizadeh, Fatemeh; Janse van Rensburg, Pieter Johan; Meyer, Walter Ernst; Nel, Jacqueline Margot; Venter, Andre (Elsevier, 2026-01)
This paper reports on the presence of deep-level defects in polycrystalline GaN thin films induced during the sputter deposition of Au Schottky barrier diodes (SBDs). The n-GaN films, with a thickness of approximately 300 nm were electrodeposited on (111) Si substrates using a low-cost method and a current density of 3 mA.cm-2 for 3 hours. Structural analysis by X-ray diffraction, scanning electron microscopy, and atomic force microscopy confirmed the polycrystalline nature and good quality of the films. Deep-level transient spectroscopy (DLTS) revealed a broad, asymmetric peak around 265 K in the as-deposited SBDs, indicating the presence of multiple defects. Laplace DLTS resolved four distinct defects with energies ranging between 0.40 eV and 0.60 eV. Thermal annealing between 450 - 500 K increased the reverse leakage current with only minor changes in the forward-bias characteristics. However, annealing at 550 K significantly reduced the leakage current by two orders of magnitude and improved the rectification ratio by one order of magnitude. All samples exhibited significant series resistance. Capacitance-voltage measurements revealed a reduction in the free carrier density near the surface, suggesting the sputter process introduced additional deep level defects. Furthermore, the deep-level energy (and therefore the likely defect composition) was found to be sensitive to the annealing temperature. HIGHLIGHTS • Sputtering-induced deep levels identified by Laplace DLTS. • Evolution of these defects during annealing at 450-550 K. • Correlation of the deep-level spectra with important diode parameters (Rs, Φb, n). • Enhanced diode performance after 550 K annealing.
The role of welfare regimes on socioeconomic inequalities in edentulism : a cross-national analysis of 40 countries
Celeste, Roger Keller; Guarnizo-Herreño, Carol C.; Fritzell, Johan; Costa, Francine S.; Ayo-Yusuf, Olalekan Abdulwahab; Barros, Aluisio J.D.; Li, Huihua; Hariyani, Ninuk; Hackley, Donna M.; Blanco, Silvana; Gamonal, Jorge A.; Maupomé, Gerardo; Watt, Richard Geddie; Peres, Marco Aurélio De A. (Elsevier, 2026-04)
BACKGROUND : We aim to evaluate the association between welfare regimes and edentulism (total tooth loss) and to investigate whether welfare regimes modify the magnitude of socioeconomic inequalities in edentulism. METHODS : The Lancet Commission on Oral Health gathered and analysed nationally representative available data from 40 high, middle- and low-income countries, collected between 2007 and 2018. The study included 117,397 individuals 20 years or older. The outcome was edentulism, defined as the absence of all natural teeth. We categorised countries into seven welfare regimes, which served as both the primary exposure and an effect modifier. Individual-level variables included sex, age and a composite measure of socioeconomic position: “wealth” measured in quintiles. Inverse probability of treatment weight and multilevel logistic regression were employed to estimate the odds of being edentulous, and cross–level interaction terms between wealth and country factors. FINDINGS : Individuals at the lowest wealth quintile had the highest prevalence of edentulism in all regimes. The highest age-sex standardised prevalence was found in Eastern European countries (8.4%, 95% Confidence Interval: 7.6–9.3), followed by Corporative (8.1%, 95% CI: 7.0–9.3), while the lowest was among the Insecurity regime (0.8%, 95% CI: 0.4–1.5), followed by the Scandinavian regime (4.7%, 95% CI: 3.5–6.1). Liberal countries presented the highest magnitude of absolute and relative inequalities, where the lowest quintile had OR = 20.6 (95% CI: 15.3–27.8) times higher likelihood of being edentulous and 17.3 percentage points (pp) higher prevalence. Low-income countries in the Insecurity regime presented the lowest level of inequality. Among high- and upper-middle income countries, the Scandinavian regime had the lowest absolute inequalities (5.5 pp difference between highest and lowest quintiles). The Informal Security regime had the lowest relative differences between the highest and lowest quintiles (OR = 2.20, 95% CI: 1.06–4.59). INTERPRETATION : Our findings indicate that some welfare regime policies may enhance oral health while decreasing socioeconomic inequalities. Higher prevalence and inequalities among industrialised countries may reflect higher levels of oral health hazards.
Natural acids as catalysts for the continuous flow production of the green solvent 2,2,5,5-tetramethyltetrahydrofuran
Currie, Bernice Mercia; Van Vuuren, Estefan; Jugmohan, Jaimee; Panayides, Jenny Lee; Riley, Darren Lyall (Elsevier, 2026-06)
As the demand for chemists to adhere to green chemistry principles increases, so does the demand for green solvents. Unfortunately, many green solvents, such as 2,2,5,5-tetramethyltetrahydrofuran (TMTHF), are costly and difficult to source. Traditional synthesis of TMTHF from 2,5-dimethyl-2,5-hexanediol has been reported to be catalysed by acids such as phosphoric and sulfuric acid, or, more recently, by H-beta zeolite. Although H-beta zeolite catalysts are high-yielding and selective, the energy required for their regeneration is high, and their production has questionable environmental impacts. A new approach was developed using flow technologies and naturally occurring acids as catalysts for TMTHF synthesis. Flow technologies are scalable, safe, efficient, and reproducible for daily chemical reactions, aligning with principles of green chemistry. This study observed several key improvements, including i) the use of a natural acid as a catalyst, ii) the use of water as a solvent, and iii) a continuous process for multigram-scale synthesis of TMTHF using citric acid monohydrate, with a yield of 72 %, resulting in a throughput of 8.24 g h−1 (9.43 kg L −1 h−1 space-time yield).
Managing variations in meaning : guidance for using complexity and related terms
Sutherland, Joshua; Beale, Dean; Dazzi, Francesco; Singer, Janet; Smith, Gary; Oosthuizen, Rudolph; Lanza, Alfonso; Cureton, Ken; McKinney, Dorothy (Wiley, 2026-01)
The term “Complexity” is widely used across disciplines, where it often represents distinct but related concepts such as complicatedness, emergence, difficulty, uncertainty, and chaos. This variability in usage can create miscommunication and misunderstanding, even within structured organizations like the International Council on Systems Engineering (INCOSE). This paper addresses this challenge by offering guidance tailored to three primary audiences—General/Casual, Practitioner, and Research—on using and interpreting “Complexity” effectively across trans-disciplinary contexts. Unlike efforts that prescribe a single definition, the approach here respects the variety of interpretations while providing techniques and ontologies to clarify usage. To illustrate, the paper compares different “Complexity” definitions, fostering awareness of both the similarities and distinctions. By promoting a common understanding, rather than a definition, this paper lays essential groundwork for future initiatives aimed at developing a unified scientific basis for “Complexity”, enabling clearer, more consistent communication, and application.
Perception of ecosystem services use across vegetation types and land use zones in Vhembe Biosphere Reserve, South Africa
Chirwa, Paxie W.; Tshidzumba, Ratsodo Phillip; Makhubele, Lucky; Araia, Mulugheta Ghebreslassie; Honold, Martin A.; Hilmers, Torben; Pretzsch, Hans (MDPI, 2026-01)
Sustainable management of ecosystem services (ESs) is critical for balancing human well-being with conservation goals in biosphere reserves. This study examined the spatial and socio-demographic variation in the use and perceived importance of provisioning, regulating, supporting, and cultural ESs across different vegetation types and land use zones in the Vhembe Biosphere Reserve (VBR), South Africa. Household surveys were administered to 447 randomly selected households in six rural communities. Descriptive statistics, Chi-square tests, Kruskal–Wallis tests, and Friedman mean ranking analysis were employed. Results revealed significant differences (p < 0.05) in ES distribution and value across vegetation types, land use categories, and household characteristics, including income, education, age, and gender. Provisioning services, particularly fuelwood, wild fruits, and wild vegetables, were most intensively utilized in Mountain Woodland Moist and Ironwood Forest areas due to accessibility and limited livelihood alternatives. Regulating and supporting services, including water purification, erosion control, and habitat provision, were associated with forested and traditionally protected areas. Cultural services reflected strong socio-cultural ties, especially in sacred and tourism-associated landscapes. Overall, the study highlights the multifunctional importance of forested and agroforestry systems in rural livelihoods, emphasizing the need for integrated, culturally informed, and ecologically sound land use planning to support sustainable development in the VBR.
Perceived abundance and cultural-economic use-value of tree species in the Mopane Woodlands, Mopani District, South Africa
Makhubele, Lucky; Dunbar, Audrill; Chirwa, Paxie W. (MDPI, 2026-01)
Identifying the key products of mopane woodlands, the perceived abundance of species, and the associated use values have important implications for rural communities and the sustainable use of mopane woodlands. This study examined local perceptions of tree species abundance and their associated use-values across four communities in the Mopani District, South Africa. The semi-structured questionnaire and key informant interviews were used to collect the data. The data were analyzed using descriptive statistics, the Friedman test, the Smith Salience Index, Kendall’s W, Pearson correlation, and the Fidelity test. There was a very strong level of agreement (W = 0.83) among the communities regarding the perceived abundance of tree species, and this agreement was statistically significant (χ2 = 19.85, p < 0.05). The Colophospermum mopane, Sclerocarya birrea, and Combretum imberbe are the most perceived abundant species in the study areas and have high value. The tree species with high use-value showed a positive correlation with the perceived abundance of tree species, conforming to the study’s ecological apparency hypothesis. The more apparent species had more use value and perceived abundance.
Prevalence and determinants of full immunization among children under five in sub-Saharan Africa : a systematic review and meta-analysis (2013–2025)
Dzinamarira, Tafadzwa; Mano, Oscar; Musuka, Godfrey N.; Madziva, Roda; Mataruse, Noah; Mbunge, Elliot; Nkambule, Sphamandla Josias; Moyo, Enos (Elsevier, 2026-03)
BACKGROUND : Despite global progress in childhood immunization, Sub-Saharan Africa (SSA) continues to report suboptimal coverage and high under-five mortality. This systematic review and meta-analysis assessed the prevalence and determinants of full immunization among children under five in SSA between 2013 and 2025. METHODS : We systematically searched six electronic databases for studies published between January 2013 and May 2025 that reported the prevalence and/or determinants of full immunization in SSA. Eligible studies were original, peer-reviewed quantitative research. Data were analysed using random-effects meta-analysis, with subgroup and sensitivity analyses conducted to explore heterogeneity. Determinants were synthesised using pooled odds ratios (ORs) where applicable. RESULTS : Thirty-one studies comprising 299,898 children were included. The pooled prevalence of full immunization was 51% (95% CI: 45%–58%), with substantial heterogeneity (I2 = 100%). Prevalence varied widely across studies from 6% to 96%. Subgroup analyses revealed lower coverage in recent years and in studies with larger sample sizes. Key positive determinants of full immunization included maternal education (OR = 2.70), paternal education (OR = 2.48), antenatal care attendance (OR = 0.23 for non-attendance), institutional delivery (OR = 2.99), and household wealth (OR = 2.45). Children in rural areas (OR = 0.55) and those with mothers of higher parity (OR = 0.67) were less likely to be fully immunised. CONCLUSION : Full immunization coverage in SSA remains well below global targets, with wide disparities by country, socioeconomic status, and maternal healthcare utilization. Strengthening maternal health services, improving education, and addressing health system barriers are critical to improving coverage and reducing preventable child deaths in the region.
Did the WHO recognition of snakebite as a neglected tropical disease impact national NTD master plans in 15 African countries?
Stienstra, Ymkje; Clevering, Ymkje; Kokhuis, Sanne; Amuasi, John Humphrey; Padidar, Sara; Schurer, Janna M.; Mijumbi-Deve, Rhona M.; Thomson, Rachael; Oluoch, George O.; Mbonigaba, Jean Bosco; Lalloo, David G. (Elsevier, 2026-02)
In 2018, the World Health Organization (WHO) acknowledged Snakebite Envenoming (SBE) as a Neglected Tropical Disease (NTD). The WHO set a target for 2030 to halve the number of snakebite victims and published a roadmap to assist affected countries with drafting national SBE policies. These national SBE policies define the course of action to reach country specific and global goals. In order to review the policy environment needed to reduce the burden, we studied if SBE policy was included in national NTD programmes and if it included the four WHO SBE policy aims and a vision for the integration of NTDs. National NTD masterplans were reviewed and combined with in-depth interviews focusing on stakeholders' experience with the integration of SBE in NTD programmes, and the influence of the inclusion of SBE on the NTD list. Only 18 % (2 out of 11) of 2015-2020 NTD masterplans mentioned SBE whereas all twelve countries who published masterplans for 2020-2025 included SBE and the need for an integrated approach between NTD programmes. Information on the type of activities allowing integration or the organizational aspects of an integrated approach was often missing. The extent to which the core policy aims of the WHO SBE roadmap has been elaborated differs considerably from country to country. In the interviews, several stakeholders raised the importance of improving the quality of epidemiological data to convince policy makers of its importance, to base antivenom distribution and to facilitate overall policy making. The path of improvement that has been taken since the recognition of SBE as an NTD must be continued and benefits from a closer collaboration between policymakers, researchers and healthcare workers to reduce the evidence gap and, ultimately, to improve care. HIGHLIGHTS • After the acknowledgment of SBE as NTD the national NTD masterplans more commonly included SBE. • The level of detail of SBE plans in the policy documents was low. • Stakeholders emphasized the lack of robust data on the SBE burden to lead to challenges in developing national policies.

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