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Item A predictive geometallurgical framework for flotation kinetics in complexes platinum group metal orebodies: Mode of occurrence-based modification of the Kelsall model using particle swarm optimization(2025-06) Kabemba, AM; Mutombo, Kalenda; Waters, KEMineralogical variability exerts a profound influence on the flotation performance of Platinum Group Metal (PGM) ores, particularly those from the Platreef deposit, where complex associations and textures influence recovery, grade, and kinetics. This study integrates the Mode of Occurrence (MOC) and mineral associations into a modified Kelsall flotation kinetics model, optimized using a Particle Swarm Optimization (PSO) algorithm, to improve prediction accuracy. Batch flotation tests were conducted on eight samples from two lithologies—Pegmatoidal Feldspathic Pyroxenite (P-FPX) and Feldspathic Pyroxenite (FPX)—with mineralogical characterization performed using MLA, QEMSCAN, and XRD. PGMs in liberated (L) and sulfide-associated (SL) forms accounted for up to 90.6% (FPX1), exhibiting high fast-floating fractions (θf = 0.77–0.84) and fast flotation rate constants (Kf = 1.45–1.78 min−1). In contrast, PGMs locked in silicates (G class) showed suppressed kinetics (Kf < 0.09 min−1, Ks anomalies up to 8.67 min−1) and were associated with lower recovery (P-FPX3 = 83.25%) and increased model error (P-FPX4 = 57.3). FPX lithologies achieved the highest cumulative recovery (FPX4 = 90.35%) and the best concentrate grades (FPX3 = 116.5 g/t at 1 min), while P-FPX1 had the highest gold content (10.45%) and peak recovery (94.37%). Grade-recovery profiles showed steep declines after 7 min, particularly in slow-floating types (e.g., P-FPX2, FPX2), with fast-floating lithologies stabilizing above 85% recovery at 20 min. The model yielded R2 values above 0.97 across all samples. This validates the predictive power of MOC-integrated flotation kinetics for complex PGM ores and supports its application in geometallurgical plant design. Model limitations in capturing complex locked ore textures (SAG, G classes) highlight the need for reclassification based on floatability indices and further integration of machine learning methods.Item Optimised consolidation and characterisation of TiC-SiC-reinforced AISI-4340 composite coatings for conical pick remanufacture(2025-07) Akintunde, IB; Lindsay, EE; Olakanmi, EO; Prasad, RVS; Botes, A; Pityana, Sisa L; Skhosane, Besabakhe STiC-SiC-reinforced AISI-4340 composite clads have been identified as a suitable material to remanufacture worn conical picks. However, the inherent defects in the clad produced, the industrial requirement to improve clad microhardness, and abrasive wear resistance necessitate the need for optimising laser processing and material parameters. Therefore, this research is conducted to investigate the effects of the powder feed rate, the scanning speed, the angle of inclination of the nozzle, and the yttria addition on the quality characteristics of the coating. The results show that as the feed rate increases from 6 to 8 g/min, the clad height increases, and the width decreases due to the reduced spreadability of the viscous melt pool. Clad height and width decrease as scanning speed increases from 0.4 to 0.5 m/min, attributed to reduced laser energy-powder interaction (LEPI) time. Furthermore, as the nozzle is inclined 2° and 4° away from the vertical, this results in an increased width and a reduced height due to the reduction of the beam deflection (increasing heat input) and loss of powder particles before reaching the focal point. Thus, the carbide melts (carbide dissolution) and reduces the reinforcing effect, leading to a decrease in wear resistance. Moreover, the addition of yttria lowers the dissolution temperature of the carbides, with a consequent increase in width and a lesser height of the clad. The geometric analysis of optimised clad established coatings with 2.3 mm height, minimal weld penetration (0.4 mm), and small HAZ of less than 1.4 mm produced. Furthermore, the microstructure revealed a homogenous dispersion of retained TiC particles in the morphology of the lath martensite, with minimal (2.6%) porosity. Additionally, the coating has the highest amount of TiC particles retained in the AISI-4340 matrix with an average microhardness of 1743 HV0.5 and 26.24 mm3 volume of material loss. The use of optimised clads for remanufacturing worn CM picks to be as new will adequately withstand the hardness of engrained quartz (1100-HV0.05) in the coal seam during underground cutting of the coal mass, thus mitigating the premature failure of the picks.Item Thermodynamic modeling of non-equiatomic TiVNbCrAl-based lightweight refractory high-entropy alloys (LWRHEAs) for hydrogen storage applications(2026-01) Aluko, AO; Jen, TC; Pityana, Sisa L; Mwema, FM; Mahamood, R; Akinlabi, ETHydrogen, as a clean alternative energy carrier, is a key element in the global energy transition with great potential to significantly reduce the carbon footprint of transportation and other sectors. In this context, high-entropy alloys (HEAs) have emerged as promising candidates for hydrogen storage. Among them, refractory body-centered cubic (BCC)-based HEAs have demonstrated exceptional storage properties, achieving hydrogen-to-metal ratios up to 2.0 H/M, which motivates research into novel systems under moderate conditions. However, their practical application is hindered by thermodynamic and kinetic limitations, such as low-pressure conditions, difficult activation, high hydride stabilities, and consequently, high desorption temperatures. In this study, four lightweight refractory HEAs (LWRHEAs)—Ti33V33Nb14Cr10Al10, Ti30V30Nb16Cr12Al12, Ti27V27Nb18Cr14Al14 and Ti24V24Nb20Cr16Al16—were selected from eight candidates that satisfied empirical phase criteria and were predicted to form a single BCC solid solution; their hydrogen-storage properties were then systematically characterized. Pressure-composition-temperature (PCT) curves revealed an unusually high hydrogen uptake of ∼2.0 H/M at 25 and 100 °C. The equilibrium plateau pressure increased steadily with composition, reaching nearly 1 bar for Ti24V24Nb20Cr16Al16. Gravimetric capacity indicated a steady, marginal variations with Nb/Cr/Al additions ranging from 3.60 to 3.68 wt% as the valence electron concentration (VEC) value increases, showing a remarkable capacity not commonly reported in BCC-based alloys. This study provides important insights into the compositional tuning of TiV-based BCC HEAs, demonstrating the effective synergy of Al/Cr additions with increased Nb content, and thereby offers guidance for the design of novel LWRHEAs for advanced hydrogen storage applications.Item Electrolysis and biomass pyrolysis pathways for green hydrogen: Technological progress and policy insights for South Africa(2025-02) Olifant, GE; Seroka, Ntalane SGrowing global energy demand and the imperative to reduce greenhouse gas emissions have accelerated interest in low-carbon hydrogen production. This review synthesizes advances at the intersection of electrolysis and biomass pyrolysis, with particular emphasis on the emerging role of biochar as a functional and catalytic material that enhances hydrogen generation while supporting sustainable bioenergy value chains. Recent evidence shows that biochar-assisted water electrolysis (BAWE) can lower energy requirements, improve reaction efficiency, and valorize locally available biomass resources. This positions biochar as a promising complement to conventional green hydrogen pathways. The review further assesses South Africa’s evolving policy and regulatory architecture by highlighting the country’s ambition to build a competitive hydrogen economy alongside structural constraints such as limited electrolyzer manufacturing capability, inadequate infrastructure, and insufficiently targeted frameworks for technology scale-up. The review analysis therefore emphasizes that integrating biomass-derived materials into hydrogen production presents an underexplored yet high-potential route for advancing national decarbonization goals. Strengthened research, development, and innovation systems, supported by coherent and technology-specific policy measures, will be essential for South Africa to unlock the full economic, environmental, and industrial benefits of a green hydrogen and biochar-integrated future.Item The incorporation of the plastic-coated aggregates into a South African asphalt mixture(2025-03) Mturi, G; Ncolosi, N; O’Connell, Johannes S; Simelane, Melusi SThe use of plastic waste in asphalt pavements has been studied internationally. However, only a limited number of studies have been conducted in South Africa that focus on non-recycled plastic waste. This article focuses on the incorporation of LDPE (Low-Density Polythene) plastic waste into South African asphalt mixes via the ‘dry’ modification method. The purpose was to evaluate the effect of LDPE plastic waste on the volumetric and performance properties of an asphalt mixture at optimum bitumen content. Contrary to other research findings, the added LDPE plastic waste did not act as a binder replacement because the bitumen content at the optimum binder content of the asphalt mix remained unchanged after plastic waste addition. Instead, the plastic waste introduced an additional binding effect between the aggregates. The asphalt mix with plastic-coated aggregates (PCA) showed improved resistance to rutting, in line with the improved asphalt stiffness and elasticity at elevated temperatures.Item Formation of titanium carbide MMC and modelling the chemical effect on powder density for additive manufacturing(2026-02) Mfusi, Busisiwe J; Mathe, Ntombizodwa R; Bisset, H; Modiba, Rosinah; Popoola, PAITitanium carbide has developed into an exceptional reinforcement contender in Aluminium Matrix Composites (AMCs) because of its greater characteristics such as elevated hardness, elevated elastic modulus, low heat conductivity, and constancy at moderately elevated temperatures. Furthermore, it is consequently selected as the reinforcing segment in AMCs because of its good thermodynamic and wettability stability inside the aluminium melt pool. In this work, titanium carbide powder was mixed to distinguish AlSi10Mg strengthen ing by the additive manufacturing (AM) process in the category of powder bed identified as Powder Bed Fusion (PBF). The objective of the study was to have homogeneously mixed powders for processing on the reinforcement of AlSi10Mg with TiC. Different characterisa tion procedures were carried out, such as scanning electron microscope energy dispersive X-ray spectroscopy (SEM-EDS), pycnometry, and thermogravimetric analysis (TGA). Theadvancement of powder density from 2.65 to 2.72 g/cm3 and surface area from 0.02 to 0.14 m2/g was accomplished. The modelling findings concurred that the addition of Ti and C increases the density of the alloy, with Ti contributing more to AlSi than C. It was deduced that with Ti and C added to the system, the bulk modulus increases, with Al6Si8TiC having the largest value of 80.34 GPa.Item Health assessment and restoration options for the degraded Swartkops Estuary, South Africa(2025-04) Adams, JB; Tsipa, V; Van Niekerk, Lara; James, NC; Lamberth, SJ; Madikizela, B; Riddin, T; Rishworth, GM; Snow, GC; Taljaard, SusanThe Global Biodiversity Framework and UN decade of Ecosystem Restoration have focused attention on the need for health assessments and restoration options for estuaries. This study focused on the Swartkops Estuary because of its biodiversity and socio-economic importance that are threatened by pressures from surrounding development and human activities. The ‘Present Ecological State’ (PES) was assessed using an estuarine health index to determine the health score of the estuary compared to historical reference conditions, using both abiotic and biotic indices. Results showed that nutrient-rich freshwater from upstream wastewater treatment works and stormwater canals has increased freshwater inflow to the estuary by 41% compared to natural, leading to eutrophication and persistent harmful algal blooms. Development and disturbance have transformed the estuary functional zone, impacting on macrophyte and bird abundances. Invertebrate bait organisms and linefish species are overexploited. As a result, the health of the Swartkops Estuary has continued its downward trajectory from 53% of its natural state in 2015 to 47% at present. This study is the first to identify potential remediation measures aimed at improving the current ecological health of the estuary. These include the removal of wastewater inputs and the restoration of salt marsh habitat, which would improve the ecological status from a largely modified to moderately modified condition. This study highlights how difficult it is to restore an estuary once deteriorated, while emphasising the need for an implemented estuary management plan with well-defined management, conservation, and restoration goals.Item Techno-economic, environmental, and social multi-objective optimization of a grid-connected hybrid renewable energy system using metaheuristic algorithms(2025-09) Dheda, D; Albertyn, J; Adetunji, K; Liu, Z; Abu-Mahfouz, Adnan MI; Cheng, LThe transition from fossil fuels to renewable energy demands energy systems that are not only technically and economically sound but also environmentally and socially sustainable. This study proposed a novel multi-objective optimisation (MOO) framework for the design of a grid-connected hybrid renewable energy system (GC-HRES) that explicitly integrated Job Creation (JC) as a fourth objective along with traditional technical, economic, and environmental objectives, such as Loss of Power Supply Probability (LPSP), Cost of Energy (COE), and Renewable Energy Fraction (REF). Prior studies often treated JC as a post-optimisation metric, while this study incorporated JC into the MOO using employment technology-specific factors. Metaheuristic algorithms, Multi-Objective Particle Swarm Optimisation (MOPSO) and Non-Dominated Sorting Genetic Algorithm II (NSGA-II), were applied to find the optimal number of solar panels, wind turbines, and battery banks under scenarios which excluded and included JC. The results demonstrated that including JC reshaped the Pareto front, revealed new objective compromises and led to diverse configurations. MOPSO favoured solutions with higher JC and REF at the expense of cost and reliability, while NSGA-II achieved more balanced, cost-effective and reliable solutions with competitive JC values. Additional constraint sensitivity analysis further demonstrated the influence of battery bank constraints on solution feasibility. The results highlighted that integrating JC into the optimisation framework enriched design possibilities and fostered a more inclusive transition to renewable energy with a focus on GC-HRESs. This paper provided a flexible and replicable MOO framework that sets the foundation for socially attuned GC-HRES designs that align with broader sustainability goals.Item Production of middle distillates through olefin oligomerization using ZSM-5 as a catalyst(2026-01) Hoyi, T; Mdleleni, MM; Seroka, Ntalane S; Khotseng, LThe global transportation sector relies heavily on gasoline (C5–C12) and diesel (C11–C24), which together account for approximately 60% of its energy needs. Driven by rapid industrialization and urbanization, diesel consumption is outpacing gasoline, with projections estimating global demand by 2035 at 27 million barrels per day for gasoline and 37 million barrels per day for diesel. To meet the rising demand for middle distillates like diesel, olefin oligomerization using ZSM-5 catalysts offers a promising approach to convert light olefins into diesel fuel. Light naphtha, a fluid catalytic cracking (FCC) product rich in C5–C6 olefins, serves as a suitable feedstock for this process. This review examines advancements in diesel production through olefin oligomerization, highlighting the efficacy of hierarchical ZSM-5 catalysts, which enhance fuel production efficiency through improved pore structures. It also explores sustainable feedstocks, such as light cracked naphtha, which reduce environmental impact, and discusses refinery strategies like FCC unit optimization to boost olefin yields. Current trends, operational dieselization strategies, and research gaps are analyzed to provide a comprehensive overview of sustainable diesel production pathways.Item Long-term joint distribution of environmental conditions at four sites in South China and South African Seas: A comparative study for offshore wind applications(2026-10) Shui, Y; Kieviet, Johan; Erfort, G; Cheng, Z; Ma, Y; Chen, POffshore wind turbines are vital for sustainable energy but face deployment challenges due to extreme envi ronmental conditions. Accurate environmental modeling is crucial for optimal design, yet comprehensive data for the South China Sea and South African Sea remains scarce. This study addresses these gaps by establishing joint probability distributions of wind speed (Uw), significant wave height (Hs), and peak wave period (Tp) using ERA5 reanalysis data (2004–2023). Validation against 20-year buoy data from Slangkop (South Africa) shows good agreement, with extreme value discrepancies below 10 %. The framework integrates Weibull and lognormal marginal distributions validated via probability plot paper and employs a binning strategy to stabilize parameter estimation. Conditional dependencies are modeled through power-law relationships (Uw, Hs) and lognormal distribution (Tp), while the Rosenblatt transformation derives 50-year environmental contour surfaces for probabilistic extreme condition prediction. Results reveal distinct regional contrasts: the South China Sea exhibits higher wind speeds with moderate waves, whereas the South African Sea experiences similar winds but more severe waves. These findings emphasize the need for region-specific turbine designs—prioritizing motion stability in the South China Sea and resonance mitigation in the South African Sea. This study suggests continuous data integration to enhance reliability under extreme conditions.Item High-energy generation of arbitrary cylindrical vector vortex beams using a modified Mach–Zehnder interferometer(2025-03) Harrison, Justin; Mphuthi, Nokwazi; Mabena, Chemist M; Naidoo, DarrylIn this paper, we demonstrate the interferometric generation of high-energy pulsed vector vortex beams at arbitrary points on the higher-order Poincaré sphere. Scalar vortex beams with topological charges ℓ=1 and ℓ=2 were produced using fused silica spiral phase plates and a 1064 nm wavelength Gaussian laser source, delivering a pulse energy of 2.75 mJ at a frequency of 1 kHz with a pulse duration of 15.5 ns. A novel, to our knowledge, modified Mach-Zehnder interferometer was constructed to allow for arbitrary inter-modal phase and amplitude control of the vector vortex states across the surface of the Poincaré sphere, achieving pulse energies of 2.5 mJ and peak powers exceeding 160 kW. This marks the highest, to the best of our knowledge, pulse energy achieved for arbitrary higher-order vector vortex beams on the HOPS.Item National biodiversity and ecosystem assessments for conservation impact: Uptake and lessons learnt from the South African experience(2025-11) Da Silva, JM; Seymour, CL; Harris, LR; Van Niekerk, Lara; Dayaram, A; Driver, A; Kgomo, T; Khatieb, S; Msweli, ST; Sink, KTo combat global biodiversity decline, countries must identify priority ecosystems and species, often through National Ecosystem or Biodiversity Assessments (NEAs/NBAs). In developing nations, resource constraints make effective uptake critical. South Africa has conducted three NBAs (2004, 2011, 2018), which have influenced policy and practice, though their impact has never been quantitatively assessed. This study evaluates NBA uptake via citation tracking, an online survey, and an application inventory. Citations revealed strong academic use, while the survey showed relevance in spatial planning, conservation actions, and environmental assessments. The application inventory demonstrated NBA influence beyond biodiversity, extending to areas like water security. Understanding NBA uptake is key to maximising its impact. We distil two decades of experience into lessons to improve future NBA uptake in South Africa and support implementation in other countries.Item Dissolved organic matter dynamics in South African nearshore waters and freshwater systems: Linkages to changing human activity, episodic events, and biodiversity(2026-02) Catipovic, L; Tzortziou, M; Turner, KJ; Harringmeyer, J; Goes, J; Gomes, H; Wu, J; O'Shea, RE; Lain, Lisl R; Smith, Marié EThe biodiverse and rapidly changing Greater Cape Floristic Region (GCFR) of southern Africa is outlined by coastal bays that receive dissolved organic matter (DOM) from rivers draining complex catchments composed of natural, agricultural, and urban land classes. As part of NASA's BioSCape field campaign (October–November 2023), we characterized the optical properties of three GCFR coastal bays (St. Helena, Walker, and Algoa) and four inland systems (Rietvlei wetland, Zeekoevlei lake, Theewaterskloof dam, and the Klein River estuary) in relation to DOM biogeochemistry and carbon cycling. Measurements of the optical properties of colored DOM (CDOM), including absorption at 300 nm (ag300), spectral slope (S275–295), and fluorescence, highlighted the bio‐optical complexity associated with terrestrial influences, urban disturbances, intense biological activity, and rapid transformations along this dynamic coastline. CDOM in the coastal bays was characterized by an order of magnitude lower ag300 (0.5–2.8 m− 1 ) and considerably higher S275–295 (0.020–0.031 nm− 1) compared to upstream waters(25–71 m− 1 and 0.012–0.019 nm− 1, respectively), suggesting intense biological production and/or photochemical degradation. Coastal DOM was mostly (>75%) composed of protein‐like compounds indicative of primary production, whereas inland DOM was mostly composed of terrigenous humic materials and had higher overall fluorescence signal. Satellite retrievals, using Sentinel‐3 OLCI and Sentinel‐2 MSI imagery, captured the relative influence of different rivers on coastal DOM dynamics and revealed that episodic events—extended periods of drought punctuated by heavy precipitation—are the primary drivers of biogeochemical variability along this globally significant, coastal biodiversity hotspot.Item Formulation of hybrid-carbide reinforced AISI-4340 wear-resistant composite coatings for remanufacturing of conical picks used in coal mining by laser cladding(2025-12) Akintunde, IB; Lindsay, EE; Olakanmi, EO; Prasad, RVS; Botes, A; Pityana, Sisa L; Skhosane, Besabakhe SThe presence of quartz (1100-HV0.05) hardness in coal seams results in premature failure of conical picks in the continuous miner (CM) cutter during underground coal mining. This requires that picks are remanufactured with materials that have improved wear resistance, which can withstand quartz. Processability of two laser-cladded hybrid-carbide (WC-SiC and TiC-SiC) reinforced AISI-4340 composite coatings was studied to identify an appropriate material for remanufacturing worn picks with particular attention paid to their microstructural evolution, performance, and costs. WC-SiC reinforced composites were characterised with defective fusion, cracks, and serrations within the clad microstructure, while the morphologies of TiC-SiC reinforced coatings revealed minimal porosity and cracks without serrations. Furthermore, the microhardness of TiC-SiC coatings is between 1102 and 2753 HV0.5, compared to WC-SiC coatings with a microhardness range between 1066 and 1365 HV0.5. Higher microhardness values of TiC-SiC coatings are attributed to the larger TiC particles retained, compared with the minimal quantity of WC retained particles that settled at the bottom of the coatings. In addition, TiC-SiC coatings have improved wear resistance with a volume loss of 33 mm3 as compared to 71 mm3 for WC-SiC coatings. Comparative analysis of the performance and cost indices of hybrid composites with those of TiC-AISI 4340 and WC-AISI 4340 composites suggests that the hybrid TiC-SiC reinforced AISI-4340 composite performs best at a lower cost. Hybrid TiC-SiC reinforced AISI-4340 composite is hereby recommended as a cheaper remanufacturing material for restoring damaged CM’s picks to as new in performance or reinforcing newly purchased picks to prolong their service life during coal mining.Item Combustion characteristics of dual swirl low nitrogen burners in small gas boilers(2025) Xiangyun, L; Zhu, L; LiangDe, L; XiuFang, K; Haitao, ZhengSwirl combustion technology is an effective method for achieving low-nitrogen (low NOx) combustion. In this study, we designed a dual-swirl low-NOx burner with the goal of minimizing NOx emissions. and the burner was evaluated in a 20t/h gas boiler through numerical simulation and experimentation. Swirl angles and excess air coefficients (1.0 to 1.20) of the burner were tested within the range of 1.0 to 1.2. The results indicated that the optimal swirl plate angles were 35° internally and 55° externally. The optimal excess air coefficient was 1.15, which balances heat transfer efficiency and minimize NOx emissions. Results show that the dual swirl combustion system can effectively reduce nitrogen oxide emissions in small gas boilers.Item Cross-realm biodiversity profile of the South African coastal zone(2025-04) Harris, LH; Adams, JB; Dayaram, A; Dunga, LV; Job, N; Kirkman, SP; Lamberth, SJ; Pfaff, MC; Van Deventer, Heidi; Van Niekerk, LaraSouth Africa’s coast is 3 113 km long and includes microtidal shores that experience semi-diurnal tides and mostly high wave energy. From west to east, the cool Benguela Current and the warm Agulhas Current drive steep gradients in climate and environmental conditions, resulting in diverse coastal ecosystem types. Here, we review the biodiversity of South Africa’s coastal zone, focusing on the constituent ecosystem types from the terrestrial, freshwater, estuarine and marine realms, and provide a brief overview of cross-realm biodiversity patterns. We also give guidance on coastal boundaries to improve standardisation in this complex area to support assessment, planning and management. The ecologically determined coastal zone currently comprises 193 ecosystem types: 83 vegetation types (e.g. seashore vegetation, strandveld, duneveld, coastal forest); 22 estuary and 3 micro-estuary ecosystem types; and 85 marine ecosystem types (e.g. shores, islands, reefs, kelp forests, bays), with planned inclusion of freshwater types (e.g. coastal lakes, forested wetlands, dune slacks) in the future. Species richness is generally highest along the south and east coasts, with the highest levels of endemism mostly reported for the south coast. The South African coast is a national asset that warrants careful management for long-term sustainability to safeguard its unique biodiversity and many associated benefits for current and future generations.Item Healthy estuaries enhance climate change resilience for fish within South African coastal seascapes(2026-07) James, NC; Edworthy, C; Van Niekerk, Lara; Lamberth, SJ; Adams, JB; Whitfield, AK; Deyzel, SHPThe capacity for estuaries in coastal seascapes to locally mitigate the effects of regional climate change should be considered in adaptation planning. In this paper we review work undertaken in South Africa’s warm-temperate estuaries to examine factors that promote climate change resilience for estuaries and associated fish and also the potential refuge provided by estuaries from climate change impacts within coastal seascapes. The thermal refuge provided by the middle and upper reaches of permanently open marine dominated estuaries for fish species is illustrated from long-term temperature monitoring in estuaries and adjacent coastlines. During extreme temperature events in the nearshore and lower estuary reaches, minimal thermal variability is maintained in middle and upper estuarine reaches, thus providing biota with a refuge against extreme thermal variability. In healthy estuaries seagrass meadows are particularly important nursery habitats, which have the added ecosystem service of maintaining pH stability and providing ocean acidification refuges for associated fauna. However, this refuge potential (resilience) declined when high water temperatures associated with a marine heat wave, interacting with nutrient enrichment, caused macroalgae blooms in seagrass meadows. We identified estuaries in the warm-temperate region that potentially provide temperature and pH refuge based on their key features (connection to the sea, habitat availability and extent). In the warm-temperate seascape 13 estuaries with marine dominated middle reaches potentially provide thermal refuge for stenohaline species seeking refuge from thermal stress. Extensive seagrass beds potentially providing ocean acidification refuges are found in 10 of these 13 estuaries. Fish communities in healthy refuge estuaries (defined as estuaries with minimal habitat alteration and loss) are more resilient to climate change impacts than those in altered systems, with eutrophication being the primary anthropogenic driver of change.Item Exploring metallic nanoparticles for enhanced multiplexed SERS for diagnostics(2025-03) Thwala, Nomcebo L; Thobakgale, Setumo L; Mcotshana, Zenande KS; Tlomatsane, Moratoa HC; Ombinda-Lemboumba, Saturnin; Lugongolo, Masixole Y; Mthunzi-Kufa, PatienceWhen it comes to diagnostics and disease management, while physicians focus on the prognosis and mortality caused by viral diseases, it is necessary to be thorough about metabolic chronic illnesses that could cause complications. Owing to its remarkable sensitivity and capability for multiplexing, Surface-Enhanced Raman Spectroscopy (SERS) emerges as a potent analytical approach with substantial promise in the realms of bioanalysis and diagnostics. This work focuses on exploring metallic nanoparticles that can be used for SERS- based pathogen and metabolic disorder-biomarkers detection for rapid viral infection and chronic disease diagnosis using SARS-CoV-2 or HIV pseudo-virus and a diabetes biomarker, glucose. Herein, metallic nanoparticles (NPs) such as gold (Au) and silver (Ag) nanoparticles, were assessed for their sensitivity in detecting both disease-biomarkers in a buffer containing HIV pseudo-virus and glucose.Item Synthesis of an 8-membered oxygen-containing benzo-fused heterocycle using flow technologies – an exercise in undertaking research with sustainability as a driver(2025-03) Currie, BM; Neyt-Galetti, NC; Olivier, T; Van der Merwe, P; Dibokwane, LS; Reinhardt, AM; Van Wyk, LT; Panayides, Jenny-Lee; Rile, DLDue to their natural abundance and biological properties, benzo-fused heterocycles are attractive targets in the field of drug discovery. Previously, a synthetic strategy for accessing 5-, 6-, 7- and 8-membered oxygen-containing benzo-fused heterocycles with the oxygen atom in the less commonly encountered 2-position was reported, however, the approach was hindered by long reaction times and a reliance on high boiling point solvents such as DMF. Targeting an 8-membered analogue as an exemplar, we highlighted that the adoption of basic green chemistry principles coupled with the use of flow chemistry techniques could be utilised (with limited development time) to improve day-to-day sustainability when performing synthetic research. In the case in hand, several key improvements were noted including (i) a higher overall yield (37% vs. 26%), (ii) a significantly reduced reaction time (110 min vs. 136 h) and (iii) the avoidance of the undesirable solvent DMF.Item Design of energetic molecular hybrids of 2-(dinitromethylene)-1,3-diazacyclopentane (DNDZ) and calculation of their detonation performance parameter(2025-07) Thungatha, Lamla; Ngcebesha, Pholisa; Mahlase, Andrew CKTheoretical design of molecular hybrids of 2-(dinitromethylene)-1,3-diazacyclopentane (DNDZ) (a derivative of FOX7) was done by linking the DNDZ to known energetic materials via a -CH 2- chain. A total of 12 novel molecular hybrids of DNDZ were designed, and their performance parameters were studied computationally. All the calculations for the molecules were done successfully to obtain these properties, which were further compared with DNDZ and RDX. Molecule 1, a hybrid of DNDZ and 2,3,4,5-tetranitro-1H-pyrrole, performed way better than the rest of the molecules and even better than DNDZ and RDX. As much as this molecule has the best detonation parameter, it is very sensitive to impact with the calculated impact sensitivity (IS) of 6 J. Molecule 12 has detonation performance better than all the molecules except molecule 1, and it has a good balance between detonation performance and impact sensitivity as compared to molecule 1.