University of Venda

The toxicity of lead and instability remain primary obstacles limiting the widespread application of perovskite materials. Two-dimensional (2D) perovskites have demonstrated significantly improved stability compared to their three-dimensional (3D) counterparts due to enhanced hydrophobicity and resistance to degradation. However, studies investigating the thermoelectric potential of 2D perovskites remain limited, underscoring the need for a deeper understanding of their behavior and scalability for electronic and thermoelectric applications. In this study, density functional theory (DFT) is employed to investigate the structural stability, electronic properties, and thermoelectric performance of graphene-enhanced 2D (BA)₂SnI₄ perovskites. Graphene is of particular interest due to its large surface area, flexibility, transparency, and high charge-carrier mobility. Our results indicate that pristine (BA)₂SnI₄ exhibit semiconducting characteristics with well-defined band gap, making it suitable as a light-absorbing layer in optoelectronic devices. It also exhibits excellent thermoelectric performance, with a high Seebeck coefficient, peak power factor of 1.6 × 10⁻² W·m⁻¹·K⁻², and maximum figure of merit (ZT) of 3.5 at 100 K, making it ideal for low-temperature thermoelectric applications. Moreover, incorporating graphene improves electrical conductivity and stabilizes the power factor at 200–800 K, increases thermal conductivity while lowering the Seebeck coefficient and ZT to < 0.3. These results reveal an offset between stability and thermoelectric efficiency, pristine (BA)₂SnI₄ is optimal for low-temperature thermoelectrics, whereas graphene-modified systems, despite having lower ZT, are promising for moderate-to-high temperature applications wherein enhanced conductivity and thermal stability are crucial.

Little is known about the vertical and spatial dynamics of microplastics in relation to hydrology and land use, particularly in African context. This study aimed to assess the abundance, type, colour and vertical distribution of microplastics in sediment from two Ramsar-designated wetlands, the Makuleke and Nylsvley. Sediment core samples were collected from five depth intervals (Depth: 0-20, 20-40, 40-60, 60-80 and 80-100 cm) for microplastic quantification. Microplastics were detected across all depths, with slight variations. Fibres and beads had high abundance in relation to other types. Makuleke exhibited significantly high concentrations of fragments and films than Nylsvley, driven largely by hydrological connectivity and anthropogenic inputs. These findings suggest that wetland protection status alone does not shield against microplastic contamination, which can persist in deep substrate layers for extended periods. Furthermore, the findings highlight the importance of integrated wetland management, enhanced plastic waste policies and ongoing research on the fate of microplastics in freshwater sediment systems.

The study of processing wild edible succulent plants such as the spekboom (Portulacaria afra) as a nutritional and functional food source is crucial for improving food security, combating malnutrition, and promoting dietary diversity. This study evaluated the effect of steaming, a traditional food processing method on enhancing the nutritional and functional properties of the spekboom plant leaves. Fresh leaves were steamed at 100 degrees C for 4 min, blended into a pulp, frozen, freeze-dried, and milled into a powder. The resulting powder was analysed for its nutritional composition, health-promoting, and functional properties. The results indicated that steaming significantly improved the nutritional profile, increasing fibre content by 14.07% and protein by 12.06%. Phytochemical levels were also enhanced, with total phenolic content reaching 15.14 mg GAE/g and total flavonoid content 15.52 mg/QE/g. Antioxidant activity increased markedly, as shown by 2,2-azinobis-(3-ethylbenzthiazolin-6-sulphonic acid) (26.73 mM TE/g) and ferric reducing antioxidant power (FRAP) (95.72 mu mol TE/g). Gas chromatography-mass spectrometry analysis revealed increased average peak areas of several amino acid metabolites following steaming. Functional properties were also enhanced, with water and oil absorption capacities increasing 6-10 g/g. Additionally, pasting properties showed a higher peak and final viscosities, suggesting improved gel strength and stability. Overall, steaming enhanced the nutritional quality, functional characteristics, and potential health benefits of spekboom. These findings highlight the value of processing wild edible succulent plants to improve their suitability and appeal as nutrient-rich ingredients human diet consumption.

First-principles approach was used to explore the structural, mechanical, electronic and optical properties of the chalcogenide compound La _2 ZrSe _5 in its orthorhombic phase. To the best of one’s knowledge, a number of this compound’s physical characteristics, including its electronic properties, mechanical behavior, optical dispersion behavior and vibrational characteristics are still understudied. The calculated lattice parameters and unit cell volume are compared with those from previous research to check the reliability of our findings. By analyzing its elastic constants, the mechanical stability of La _2 ZrSe _5 is evaluated, showing its mechanical resilience. The material’s analysis of mechanical descriptors, including the independent elastic coefficients of bulk, shear and Young’s modulus, as well as ratios such as Pugh’s and Poisson’s ratio, suggests anisotropic and ductile behavior. The electronic properties were further examined by figuring out the band structure, partial and total density of states. According to the findings, La _2 ZrSe _5 is a semiconductor with a fundamental band gap of approximately 1.25 eV as computed using hybrid functional, suggesting that it may find use in optoelectronics such as photodetectors, field effect transistors, light-emitting diodes and electronics. This work will provide helpful guidance for future experiments and theoretical investigations of the material.

Morels (Morchella spp.), as rare and economically valuable edible mushrooms, have been rapidly cultivated in China and other regions in recent years, becoming a significant part of the agricultural economy. However, with the expansion of cultivation areas, morel diseases have become increasingly prominent. In particular, the white mold disease outbreak has severely restricted yield and quality improvement. A novel species (Mariannaea parasitica) and a new record of Mariannaea (Mariannaea parasitica) are reported from white mold-diseased fruiting bodies of Morchella based on morphology and phylogenetic analysis of ITS and LSU. The new species is characterized by erect, septate, hyaline, irregularly branched conidiophores, which often bear verticillate branches and usually produce 3-6 phialides. The phialides are ampulliformlageniform, while the conidia are hyaline, smooth-walled, ellipsoidal to ovoid, with one side concave or flattened. This study broadens our understanding of the diversity of pathogen species in cultivated morels.