Research Articles (University of Pretoria)

Permanent URI for this collectionhttp://hdl.handle.net/2263/121

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.

Access to the full text of UP theses and dissertations is available at UP Electronic Theses and Dissertations.

Information and guidelines for authors/ submitters available at http://www.ais.up.ac.za/openup/index.htm.

For inquiries regarding this collection or items in the collection, please contact : Hendriette Jansen van Vuuren
Tel.: +27 12 420 4712

Browse

Now showing 1 - 20 of 42639

Reproductive females of a cooperatively breeding rodent are in better body condition when living in large groups
Finn, K.T.; Janse van Vuuren, Andries Koch; Suess, Tobias; Hart, Daniel William; Bennett, Nigel Charles; Zottl, M. (Wiley, 2025-07)
Cooperation and group living have been suggested to facilitate survival in varying environments and under challenging conditions. However, group living may also be associated with costs, particularly in species where individuals within groups may compete for limited resources. The costs and benefits of cooperative group living on cooperatively breeding mammals in varying environments remain unclear. Here, we use data collected from wild, cooperatively breeding Natal mole-rats (Cryptomys hottentotus natalensis) inhabiting a seasonally varying environment to assess whether body condition changes between seasons and whether these changes are contingent upon group size. We demonstrate that the body condition of reproductive females improved with increasing helper number during both the benign summer and the harsher winter seasons. However, the body condition of other group members showed little dependency on group size or season. Only when including one extremely large group did the body condition of non-breeders weakly, albeit significantly, change depending on group size and seasonality. These results suggest that larger group sizes may yield some benefits for non-breeding group members during winter and may invoke some costs during summer. Group living in Natal mole-rats is likely promoted by a combination of collective foraging, thermoregulatory benefits, and potentially some indirect fitness benefits through improved body condition of the breeding female.
Fertility up in flames : reduced fertility indices as a consequence of a simulated heatwave on small African mammals
Jacobs, Paul Juan; Bennett, Nigel Charles; Du Plessis, L.; Hart, Daniel William (Wiley, 2025-03)
With the increasing frequency and intensity of heatwaves due to climate change, the survival and reproductive success of mammals could be under significant threat. However, the specific effects of these environmental stressors on mammalian reproductive fitness remain insufficiently explored. This study investigates the impact of a simulated heatwave on male fertility indices in two African rodent species: the mesic four-striped field mouse (Rhabdomys dilectus) and the Namaqua rock mouse (Micaelamys namaquensis) during the breeding season. We measured key indicators of male fertility, including testes mass, testes volume, seminiferous tubule diameter, the presence of sperm, and plasma testosterone levels. Our findings reveal that both species experienced significant effects on male fertility indices, with the smaller R. dilectus showing a decline in all fertility indices following a simulated heatwave. These results suggest that the projected increase in heatwave events may compromise the reproductive success of small mammals, potentially leading to population declines. Finally, this study highlights the need for focused studies on the effect of heatwaves on long-term reproductive success in both males and females.
Examining alterations in fGCM concentrations post-defaecation across three animal feeding classes (ruminants, hindgut fermenters and carnivores)
Osburn, Kayla Rae; Crossey, Bruce Gareth; Majelantle, Tshepiso Lesedi; Ganswindt, Andre (Wiley, 2025-05)
Quantification of faecal glucocorticoid metabolites (fGCMs) is a popular non-invasive technique for monitoring wildlife's response to stressors, demanding an understanding of the stability of fGCM concentrations post-defaecation to ensure comparability of determined fGCM values across samples. To provide species-specific recommendations for the duration within which sampling can take place, we measured the rate at which the fGCM concentrations of nine different species changed throughout a 7-day period post-defaecation. In this study, we explored the temporal dynamics of fGCM concentrations in nine species across three feeding classes (ruminants, hindgut fermenters and carnivores): impala (Aepyceros melampus), giraffe (Giraffa camelopardalis), blue wildebeest (Connochaetes taurinus), plains zebra (Equus quagga), African elephant (Loxodonta africana), white rhino (Ceratotherium simum), cheetah (Acinonyx jubatus), spotted hyena (Crocuta crocuta) and leopard (Panthera pardus). Utilizing enzyme immunoassays already established for each of the focal species, we identified broader feeding class-specific patterns. All herbivores exhibited a significant decrease in fGCM concentrations over time, starting from 6 h (impala) to 48 h (giraffe, blue wildebeest, white rhino and African elephant) post-defaecation. For carnivores, concentrations remained fairly comparable for 12–24 h, after which fGCM concentrations either decreased (spotted hyena), increased (leopard) or remained stable (cheetah), with notable variation in triplicate concentrations (cheetah and leopard). These findings offer insights into scheduling faecal sampling for endocrine monitoring, particularly from free-roaming wildlife, to ensure comparability of determined hormone metabolite concentrations. Furthermore, the species-specific variation in fGCM concentration post-defaecation demonstrated in this study underlines the necessity to investigate every new species to ensure accurate and comparable results. Future studies ought to investigate how the mass of collected material, sex and drying methodologies affect the measurement of fGCMs post-defaecation.
Endemic plants and animals are susceptible to extinction in an imperilled alpine hotspot in southern Africa
Taylor, Peter J.; Bredenhand, Emile; Monadjem, Ara; Armstrong, Adrian J.; Rakotoarivelo, Andrinajoro R.; Mdluli, Veli Monday; Howard, Alexandra; Modise, Serero; Motitsoe, Samuel N.; Ntloko, Pindiwe; Kirkaldy, Abigail P.; Kleynhans, Dewald J.; Jankielsohn, Astrid; Mosikidi, Toka; Oosthuizen, Maria Kathleen; Payne, Stephanie; Munyai, Thinandavha C.; Carbutt, Clinton; Ramoejane, Mpho; Bereng, Mosiuoa; Stiller, Michael; Haddad, Charles R.; Steenhuisen, Sandy-Lynn; Mlambo, Musa C.; Moyo, Sibusisiwe; Nyembe, Nthatisi I.; Mofokeng, Lehlohonolo; Van As, Johann; Malekana, Lesego; Daniel, Gimo M.; Gwate, Onalenna; Van As, Michelle; Harrison, James Du Guesclin; Thabethe, Nokubonga F.; Kheswa, Nozipho; Moloi, Karabo; Sishange, Nkanyiso; Clark, V. Ralph (South African National Biodiversity Institute, 2025-11)
BACKGROUND : As global temperatures rise, alpine species at the upper limit of their distribution are at risk of decline and extinction due to shrinking habitats downslope. The alpine (> 2 800 m a.s.l.) biodiversity of the Maloti-Drakensberg is poorly known but may be threatened by climate change. OBJECTIVES : Using expert BioBlitzes, we documented species richness and elevational patterns of distribution in 14 plant and animal higher taxa from alpine and upper-montane zones in an unexplored corner of the Maloti-Drakensberg. METHODS : Using standardised methods such as Sherman traps, acoustic monitoring, bird timed counts, pitfall traps, sweep nets, aquatic SASS5 kick-nets, timed searches and herbarium collections, we assessed elevational zonation of flowering plant and selected invertebrate and vertebrate diversity in the Witsieshoek Community Conservation Area (WCCA). RESULTS : GBIF records complemented expert BioBlitz data, together enumerating 1 216 plant, vertebrate and invertebrate species along an elevation gradient from 1 760 m to 3 145 m at WCCA. Birds, insects and plants showed concordant beta diversity patterns from BioBlitz and GBIF data: high turnover compared to nestedness in more sedentary insects and plants, and the opposite in more mobile birds (GBIF data not available for bats). Although identifications are ongoing, 17% of species or morphospecies were exclusively recorded in the alpine zone, including 82 species of plants and 92 of animals. CONCLUSION : Alpine endemics are vulnerable to the ‘escalator to extinction’ process due to climate change. Surveys of under-explored alpine hotspots should be prioritised, drawing on mountain tourism-based citizen science. We advocate an ecotourism- and community-centred, restoration and rewilding approach for this strategic and biodiverse community conservation area.
A South African perspective on the 2023 IPBES Thematic Assessment Report on Invasive Alien Species and their control
Wilson, John R.U.; Faulkner, Katelyn T.; Winzer, L. Fernandez; Mcculloch-Jones, E.J.; Van Wilgen, B.W.; Blanchard, R.; Carbutt, C.; Dechoum, M.S.; Foxfroft, L.C.; Greve, Michelle; Hui, C.; Ivey, P.; Kgope, B.; Kumschick, S.; Le Roux, Peter Christiaan; Masehela, T.S.; Measey, J.; Miza, S.; Mogapi, T.; Mpikanisi, F.; Mulaudzi, L.; Nelukalo, K.; Nnzeru, L.; Nsikani, M.M.; Pattison, Z.; Rahlao, S.J.; Richardson, D.M.; Robinson, T.B.; Shackleton, R.T.; Tererai, F.; Tshidada, N.; Tshikhudo, P.P.; Tshivhandekano, I.; Wanjau, K.; Ziller, S.R.; Zengeya, Tsungai Alfred (South African National Biodiversity Institute, 2025-11-06)
BACKGROUND : Biological invasions are a major threat to biodiversity and sustainable development. A global assessment of biological invasions released in 2023 by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), concluded that while invasions ‘…cause dramatic and, in some cases, irreversible changes…’ they can be ‘…overcome through a context-specific integrated governance approach’. AIM : Here we evaluate insights from the IPBES assessment in the context of South Africa and explore how these insights could inform the development of a national policy and strategy to address biological invasions. RESULTS : Trends and status of biological invasions in South Africa are similar to those seen globally, but there are some distinct local nuances. South Africa has: 1) a long history of invasions with negative impacts caused especially by invasive trees and freshwater fishes, whilst invasive marine invertebrates have transformed large parts of the coastline; 2) a long history of control (biological control was first implemented in 1913) with large-scale, state-run invasive species management programmes currently in place; 3) a comprehensive regulatory system (e.g., there is provision for beneficial invasive species to be used under permits); 4) relatively high levels of awareness and engagement (at least among some stakeholder groups); and 5) a well-connected community of practice. DISCUSSION : Efforts to limit introductions (intentional or unintentional) are difficult given South Africa’s extensive and porous borders and the pressing need to increase trade and travel. Regulatory and implementation efforts aimed at prevention are improving, with the newly established Border Management Authority aiming to integrate biosecurity interventions at ports of entry. Such integrated governance is, we argue, needed more broadly if affected sectors, society groups and stakeholders are to be effectively included in decision-making and management. A more systematic flow of information from observation to action is essential, as is better feedback between research, policy and implementation at all scales. Biological invasions will continue to pose threats, but many of these can be effectively mitigated through focussed interventions. Co-ordinating such interventions in the context of other cross-cutting global change challenges and initiatives is a cost-effective way of protecting and improving livelihoods, human health, quality of life and biodiversity.
Perspective : radiotherapy and body composition: unmet meeds in low- and middle-income countries
Murphy-Alford, Alexia J.; Grossberg, Aaron J.; Baracos, Vickie E.; Barbar, Maha; Bauer, Judy; Bennett, Jonathan P.; Fidarova, Elena; Fuller, Clifton D.; Loser, Anastassia; Moreno, Amy C.; Patra, Anurima; Puttaswamy, Deepa; Rosenthal, David, I.; Schoeman, Judy; Anacak, Yavuz (Elsevier, 2026-01)
Radiotherapy plays a vital role in cancer treatment, yet its effects on patients’ nutritional status can precipitate muscle loss, with significant implications for treatment tolerance and outcomes. Evidence from high-income countries increasingly links radiation-induced muscle loss to adverse clinical outcomes. In contrast, low- and middle-income countries face a stark evidence gap, despite the heightened vulnerability of cancer patients in these settings due to delayed diagnosis, limited access to care, and high rates of co-morbidities. This paper highlights the critical gaps in nutritional care for radiotherapy patients in low- and middle-income countries. STATEMENTS OF SIGNIFICANCE : Radiotherapy can affect body composition and consequently clinical outcomes, yet evidence from low- and middle-income countries remains limited despite heightened risks from delayed care and comorbidities. This perspective argues that generating context-specific body composition data and building evidence for integrating nutrition into radiotherapy services are critical steps to optimize treatment and improve survivorship in resource-limited settings.
A novel class of orally bioavailable phenylglycine–benzoxaborole conjugates with antimalarial activity and potentially novel mechanism of action
Morake, Mokhitli; Taylor, Dale; Coertzen, Dina; Njoroge, Mathew; Krugmann, Liezl; Leshabane, Meta Kgaogelo; Da Rocha, Shante; Qahash, Tarrick; Girling, Gareth; Coyle, Rachael; Lee, Marcus C.S.; Wittlin, Sergio; Llinas, Manuel; Birkholtz, Lyn-Marie; Basarab, Gregory S.; Chibale, Kelly (American Chemical Society, 2026-01-08)
A new class of benzoxaboroles with a phenylglycine appendage was found to display in vitro blood stage activity against the human malaria parasite Plasmodium falciparum (Pf). Structure–activity relationship studies of the starting hit compound 3 resulted in compounds active against PfNF54 drug-sensitive and PfK1 drug-resistant strains with an in vitro antiplasmodium IC50 < 0.4 μM, selectivity over mammalian cell-lines (selectivity index > 47) and high aqueous solubility (160 to >200 μM). Selected compounds showed good in vitro metabolic stability when incubated with human, rat, and mouse liver microsomes and showed no cross-resistance against barcoded mutant lines. Two frontrunner compounds, 6 and 7, were dosed orally at 50 mg·kg–1 using a standard quadrupole dosing regimen in a P. berghei mouse infection model and showed encouraging in vivo efficacy. This work identifies a promising new class of phenylglycine-based benzoxaboroles, which warrants further medicinal chemistry optimization.
Decoding the genome of Brainea insignis reveals insights into fern evolution and conservation
Xia, Zengqiang; Duan, Lei; Fang, Yuhan; Jiang, Yan; Chen, Hongfeng; Yan, Yuehong; Wang, Aihua; Li, Zixiang; Liu, Ziyue; Zhao, Guohua; Shen, Hui; Van de Peer, Yves; Kang, Ming; Wang, Faguo (Nature Research, 2026-02-03)
Ferns are an ancient lineage of vascular plants, yet limited genomic resources constrain both evolutionary and conservation inference. Here, we generate a chromosome-level genome assembly for the endangered cycad fern Brainea insignis (8.62 Gb), the sole species in its genus within eupolypods II, and integrate comparative and population genomics to resolve its evolutionary history and vulnerability. The genome retains the ancient whole-genome duplication shared by leptosporangiate ferns; however, its exceptional size is driven primarily by recent repeat accumulation and further shaped by lineage-specific evolutionary signatures linked to functional specialization. Resequencing across the range identifies three geographically and environmentally structured lineages shaped by Quaternary refugia, limited postglacial expansion and localized admixture. Recently reduced populations show pronounced genomic erosion, including inbreeding and elevated genetic load, due to insufficient time for purging. We detect climate-associated local adaptation and project substantial future genetic offsets, with southwestern Indochina populations at highest risk. Our results expand fern genomics and support spatially tailored conservation strategies that maintains habitat connectivity and promotes adaptive gene flow.
Exploring strategy message affordance as mediator to strategy translation for enhanced implementation
Serfontein-Jordaan, Muriel; Pretorius, Marius; Kunz, Leanne; Letsholo, Rebaona (AOSIS, 2026-01-13)
ORIENTATION : Strategy implementation remains a persistent challenge in strategic management, with many organisations failing to bridge the gap between formulation and execution. RESEARCH PURPOSE : This study introduces the concept of strategy message affordance and investigates its role in enabling effective strategy translation, which is posited as a precursor to enhanced implementation outcomes. MOTIVATION FOR THE STUDY : Given the ongoing implementation gap observed in organisations, there is a need to explore alternative explanatory mechanisms better understand and address implementation failures. RESEARCH DESIGN, APPROACH AND METHODS : Using a qualitative research design, the study draws on semi-structured interviews conducted across two case organisations. Thematic analysis was used to identify patterns relating to message interpretation, strategic alignment and implementation dynamics. MAIN FINDINGS : The study finds that enhanced implementation is enabled when the strategy message is consistently and personally conveyed, supported by inclusive organisational culture, cohesion and open communication. Furthermore, a management team that engages directly, demonstrates contextual awareness and recognises employees as individuals fosters trust, leading to improved strategic alignment at lower levels. PRACTICAL/MANAGERIAL IMPLICATIONS : Organisations aiming to improve strategy execution should invest in deliberate, contextualised communication strategies and foster leadership behaviours that build interpersonal trust and collective understanding of the strategic agenda. CONTRIBUTION/VALUE-ADD : This study advances the strategic management literature by conceptualising SMA and linking it to implementation success via the mediating role of strategy translation.
Performance evaluation of boron/epoxy and carbon/epoxy composite patches for extending service life of damaged AA7075-T6 aircraft components
Zouambi, Leila; Fekirini, Hamida; Moller, Heinrich; Khodja, Malika (Taylor and Francis, 2026)
Despite extensive theoretical predictions, no systematic experimental comparison between boron/epoxy and carbon/epoxy patch repairs has been conducted under standardised conditions, creating a critical knowledge gap in aerospace structural maintenance. This study provides the first rigorous experimental validation of these competing repair technologies under identical ASTM E647 protocols. AA7075-T6 specimens (400 × 160 × 2 mm3) with 6 mm rivet holes and 1 mm starter cracks were repaired using single-sided composite patches and subjected to constant amplitude fatigue loading (22 kN, 10 Hz, R = 0.1). Crack propagation monitoring revealed boron/epoxy patches achieved 96,000 cycles versus 78,000 cycles for carbon/epoxy systems, a quantified 23% performance advantage. Stress intensity factor analysis demonstrated up to threefold reductions compared to unrepaired specimens, with boron/epoxy exhibiting superior crack growth retardation (da/dN rates 40% lower at equivalent ΔK values). Post-fatigue residual strength testing confirmed enhanced load-bearing capacity in both repair configurations. These benchmark experimental data validate two decades of theoretical predictions whilst establishing the first standardised comparative database for evidence-based material selection in aircraft repair programmes. The quantified performance metrics provide essential validation data for regulatory compliance and structural integrity assessments in aerospace maintenance applications.
Innovating mobility : a student competition in wheel and track design
Chen, Devin; Sonalkar, Chaitanya Shekhar; Kikuta, Riku; Peenze, Andries Jacobus; Swamy, Varsha S.; Salmon, J. Ethan; Jelinek, Bohumir; Mason, George L.; Els, Pieter Schalk; Sandu, Corina (Elsevier, 2026-04)
In this paper, we propose an ISTVS Wheel/Track Design Student Competition to engage students in terramechanics through hands-on experience in off-road mobility design and testing. The competition will challenge student teams to design and fabricate a wheel or track system for a small unmanned ground vehicle (UGV), evaluated through tractive performance and mobility tests on selected soil types. By emphasizing low-cost, practical methods, the initiative ensures accessibility for students from diverse backgrounds. Teams can use free CAD software, 3D printing, or other rapid prototyping techniques to minimize expenses. The competition will feature two main components: a laboratory-style single-wheel test rig to assess tractive performance, and a small UGV platform for field-based mobility tests. Performance metrics may include drawbar pull, sinkage, slip, traction, and slope climbing, following ISTVS standards (He et al., 2020). Each competition will include design presentations and structured scoring criteria evaluating both design quality and performance. A standardized test matrix will assess structural integrity and functional performance. This initiative provides experiential learning opportunities, encourages innovation, and strengthens student engagement with ISTVS—cultivating the next generation of terramechanics engineers.
Total synthesis of isoflavonoids
Selepe, Mamoalosi A.; Mthembu, Siyanda T.; Sonopo, Molahlehi S. (Royal Society of Chemistry, 2025-03)
Isoflavonoids are phenolic compounds with wide structural diversity and a plethora of biological activities. Owing to their structural variation and potential health-promoting and other benefits, they have been targeted for synthesis. Herein, we review the synthesis of natural isoflavonoids belonging to different classes that include isoflavones, isoflavanones, isoflavans, isoflavenes, pterocarpans, rotenoids, coumaronochromones, and coumestans. The synthetic methodologies employed and advancements in synthetic strategies are highlighted.
Editorial to the special issue on decoupling and environmental sustainability
Ryding, Daniella; Lichy, Jessica; Africa, South; Ritch, Elaine (Elsevier, 2026-02)
No abstract available.
Increasing culvert hydraulic capacity for improved climate resilience : a physical modelling analysis
Giliomee, Maria Dorothea; Loots, Ione; Van Dijk, Marco (IWA, 2025-08)
Culverts often fail to handle increased flood peaks due to urbanisation and climate change. Modifying culvert inlets to increase discharge capacity can negate the need for additional culvert barrels or to rebuild the entire structure. Although some previous studies investigated hydraulic culvert improvements, this study is the first to test different combinations of headwall and wingwall angles, and the effect of aeration vents, to improve capacity of inlet-controlled culverts. This physical modelling study evaluates various modified box and circular culvert inlets, quantifies their impact on capacity, develops a coefficient for use in standard equations, and verifies the alignment of results with established references and guidelines. A 15° headwall with a 30° wingwall added to a box culvert or a rounded inlet edge for a circular culvert improved the flow by up to 34% at a headwater depth of twice the culvert height (2D), or up to 18% at 1.2D for box culverts and 24% at 1.2D for circular culverts. An air vent after the inlet had an insignificant influence on the capacity. A novel flow improvement coefficient was developed to calculate improved capacity with existing design equations. Culvert inlet improvements will reduce flood risks and contribute to sustainable drainage infrastructure.
Coal fly ash-based adsorbents for tetracycline removal : comparative insights into modification and zeolite conversion
Houghton, Eric Emmanuel; Yapi, Litha; Haneklaus, Nils; Brink, Hendrik Gideon; Tichapondwa, Shepherd Masimba (MDPI, 2025-03-01)
Emerging xenobiotics, such as tetracycline (TC), pose significant risks to both the environment and human health. Adsorption is a recognized method for removing these contaminants, and in this study, fly ash (FA), a by-product of coal combustion, was modified to develop adsorbents. Acid-modified FA (AM-FA) and base-modified FA (BM-FA) were prepared, and zeolite Na-P1 (ZNa-P1) was synthesized via hydrothermal treatment. Adsorption tests revealed that BM-FA and ZNa-P1 removed 76% and 90% of TC, respectively, compared to 35% with unmodified FA. AM-FA had the lowest performance, removing just 11% of TC. ZNa-P1’s superior performance was linked to its high zeolite purity, with a cation exchange capacity (CEC) of 6.37 meq/g and a surface area of 35.7 m2/g. Though BM-FA had a larger surface area of 110.8 m2/g, it exhibited a lower CEC of 3.42 meq/g. Adsorption efficiency was more closely related to CEC than surface area. Optimal TC removal with ZNa-P1 was achieved at a 7.5 g/L dosage and pH 5. The process followed pseudo second order kinetics and the Langmuir isotherm, with a maximum capacity of 46.34 mg/g at 30 °C. The adsorption thermodynamics indicated that the adsorption was endothermic and spontaneous. The adsorption mechanism of tetracycline on ZNa-P1 involved electrostatic attraction, hydrogen, and ion exchange. This study aligns with SDGs 6 (Clean Water and Sanitation) and 12 (Responsible Consumption and Production).
Specialised recruitment agents in a low and middle-income country : intermediaries between employers and persons with disabilities seeking employment
Morwane, Refilwe Elizabeth; Dada, Shakila; Bornman, Juan (Sage, 2025-11)
BACKGROUND : Persons with disabilities in South Africa experience challenges in accessing training and employment opportunities. OBJECTIVE : This study aimed to determine the role of specialised recruitment agencies by exploring activities they engage in and services provided to employers and job seekers with a disability. METHOD : Twenty-five specialised recruitment agencies were interviewed through semi-structured individual telephonic interviews. A qualitative research design was employed. Data were transcribed verbatim and analysed thematically. FINDINGS : It was found that the SRAs assume four roles: recruitment, placement, trainer, and consultation. Within these roles, various services were provided, which were related to recruitment, placement, and support in equity compliance. These roles assumed by SRAs largely depended on the size of the organisation. CONCLUSION : The four roles collectively foster a supportive environment for employees with disabilities. Training dispels misconceptions, and pre- and post-employment support ensures access and accommodations. It is evident from agencies that assumed all four roles that successful placement of persons with disabilities was dependent on the provision of support within all four roles.
FPEVO : fused point-edge visual odometry for low-structured and low-textured scenes
Brown, Dylan; Grobler, Hans; De Villiers, Johan Pieter (Elsevier, 2025-11)
Visual odometry is an essential component of vision-based robotic navigation systems. A primary limitation of existing visual odometry solutions is their inability to achieve satisfactory performance in both high- and low-textured regions. In this paper, a robust RGB-D visual odometry method is proposed that fuses point and edge features. By combining the descriptiveness of feature points with the structure provided by edge data, a method that is robust to low-textured scenes is developed. Edge features are first detected and grouped based on the Gestalt principles of continuity and proximity. Edge groups are then associated between the current and previous frames using point features in the vicinity of the edges. Pose estimation is thereafter performed by first matching points between associated edge groups, filtering these points based on structural constraints imposed by the edges, and estimating the motion of the agent. Compared to state-of-the-art alternatives, such as REVO, MSC-VO, DROID-VO and SplaTAM on the TUM RGB-D, ICL-NUIM and Tartan-Air datasets, the resulting method reduces the root mean square absolute trajectory error, and translational and rotational relative pose errors by up to 58%, 75%, and 82%, respectively. This indicates that our method is not only more accurate than current approaches, but also more consistent, especially in low-structured and low-textured environments.
The optimisation and application of a novel baseScope™ RNA-ISH assay for the detection of foot-and-mouth disease virus in carrier African buffalo (Syncerus caffer) from South Africa
Henning, Alischa; Odendaal, Lieza; Loots, Angelika Katrin; Quan, Melvyn (Elsevier, 2025-12)
The detection of foot-and-mouth disease is limited to BSL-3 laboratories and its detection in carrier animals require increased test sensitivity. In-situ-hybridisation utilises the propensity of a labelled single-stranded sequence of DNA or RNA to anneal to a complementary target. It can be performed on formalin-fixed tissues and with some of the most recent advances, show an increased test sensitivity. BaseScope™ incorporates an additional signal amplification step, which makes it possible to detect RNA splicing variants, point mutations, small insertions or deletions, and short RNA targets (50–300 nucleotides). This study aimed to adjust and optimise the BaseScope™ assay to detect foot-and-mouth disease virus in a novel, carrier wildlife species, i.e., buffalo. Specific steps were adjusted to attempt to address some of the rigidity involved in the workflow. However, none of the in-house reagents or equipment attempted as an alternative to the original and prescribed workflow was successful. This demonstrates the fastidious nature of this diagnostic modality and the synergistic characteristics of a commercial assay. However, keeping tissues in formalin for up to 7 days and storing cut sections for up to 3 months did not have a negative impact on the results. This further demonstrated the reliability of BaseScope™.
Green carbon dots from pinecones and pine bark for amoxicillin and tetracycline detection : a circular economy approach
Sanni, Saheed O.; Bayode , Ajibola A.; Haneklaus, Nils H.; Fu, Lin; Shang, Jianping; Fan, Hua-Jun Shawn (MDPI, 2025-03-11)
Over the years, the abuse of antibiotics has increased, leading to their presence in the environment. Therefore, a sustainable method for detecting these substances is crucial. Researchers have explored biomass-based carbon dots (CDs) to detect various contaminants, due to their low cost, environmental friendliness, and support of a circular economy. In our study, we reported the synthesis of CDs using pinecones (PCs) and pinebark (PB) through a sustainable microwave method. We characterized the PCCDs and PBCDs using X-ray diffraction, Raman spectroscopy, Transmission Electron Microscope, and Fourier transform infrared, Ultraviolet-visible, and photoluminescence (PL) spectroscopy. The PCCDs and PBCDs were tested for the detection of amoxicillin (AMX) and tetracycline (TC). The results indicated that the sizes of the PCCDs and PBCDs were 19.2 nm and 18.39 nm, respectively, and confirmed the presence of the 002 plane of the graphitic carbon structure. They exhibited excitation wavelength dependence, good stability, and quantum yields ranging from 6% to 11%. PCCDs and PBCDs demonstrated “turn-off” detection for TC and AMX. The limits of detection (LOD) for TC across a broader concentration range were found to be 0.062 µM for PCCDs and 0.2237 µM for PBCDs. For AMX detection, PBCDs presented an LOD of 0.49 µM.
The use of soundless chemical demolition agents in large scale in situ rock breaking applications in the mining industry
Maubane, Ingrid; Ngwenyama, Philani Larrance (Southern African Institute of Mining and Metallurgy, 2025-07)
Soundless chemical demolition agents (SCDAs) are proving to be the future of large-scale rock breaking. Unlike explosives, SCDAs do not generate negative environmental effects. This allows the SCDAs to be used in areas closer to communities and sensitive infrastructure. SCDAs are currently used in small-scale rock breaking applications but have not been tested in large-scale applications. The study evaluated whether SCDAs can break large volumes of in-situ rock. This was done by conducting five trials using Nex-Pand powder in four different surface mining sites. Trial 1 was unable to break the rock due to large confinement between the holes and the use of a hole diameter that was 182% bigger than recommended. Trial 2 fractured the rock with a crack width that reached 110 mm after 72 hours. Trial 3 generated cracks at the biggest hole diameter of 102 mm. Trial 4 had the smallest crack width due to the use on a stronger rock than in other trials. Trial 5 generated cracks at a slower rate than other trials because of the use of Nex-Pand powder at a lower ambient temperature than designed. The trials proved that SCDAs can replace explosives in areas closer to sensitive structures.

Browse

Recent Submissions