ResearchSpace

Communities in ResearchSpace

Welcome to ResearchSpace, the institutional repository of the CSIR. ResearchSpace is an open access electronic archive collecting, preserving and distributing scholarly digital materials created by the CSIR.

Recent Submissions

Item

Quantum biosensing illuminates infected cells for timely disease diagnosis

(2026) Mthunzi-Kufa, Patience; Mpofu, Kelvin T

Photonics has a profound impact on daily life in numerous ways, from communication and entertainment to manufacturing and healthcare. In Africa, photonics applications in point-ofcare diagnostics, the diagnosis of substandard drugs, and treatments for cancer, diabetic wounds, and other ailments promise significant improvements in healthcare and the quality of human life. Of particular interest is that quantum technologies can be used for new forms of sensing, imaging, and computing, with potential applications in diagnostics and drug discovery. The amalgamation of biological molecules, such as deoxyribonucleic acid (DNA), proteins, or enzymes, with quantum sensors (QS), which illuminate changes in light emissions during lightmatter interactions, introduces a game-changer in rapid, sensitive, and specific disease diagnostics. Here, we theoretically demonstrate how the integration of quantum phenomena into sensing mechanisms could enable the detection of minute variations in intracellular factors, such as refractive index, cell morphology, and pH shifts in infected versus uninfected cells. We propose a conceptually designed quantum biosensing experiment that can be conducted using nitrogen vacancy (NV) centres.

Item

Using Landsat, Sentinel-1 and -2 and GEE to assess changes in wetland Ecosystem Functional Groups in the Maputaland Coastal Plain of South Africa

(2026-12) Apleni, P; Naidoo, L; Tsele, P; Van Deventer, Heidi

Consistent monitoring of wetland Ecosystem Functional Groups (EFGs) over large areas and long periods remains challenging owing to uneven availability, varying spatial resolutions, and spectral similarity of some EFGs. A Google Earth Engine (GEE)-based Earth Observation workflow was developed to map and quantify changes in wetland EFGs across the Maputaland Coastal Plain (MCP) in South Africa. The study included Landsat imagery for 1990, 2000, 2006 and 2014; and Sentinel-1 and Sentinel-2 imagery for 2018, 2020 and 2022.

Item

Microstructure, hardness, and wear behaviour of laser-cladded Inconel 625 and 718 powders on Hadfield steel

(2026) Williams, I; Maledi, Nthabiseng; Bamisaye, OS; Bodunrin, M; Skhosane, Besabakhe S; Sitimela, T

Laser cladding offers enhanced mechanical and microstructural properties in rail crossings, thereby improving the surface characteristics required for high-speed and heavy-haul rail transportation. In this study, the Inconel 625 and 718 powders were deposited on Hadfield steel to evaluate the microstructural, hardness, and wear properties. The laser-cladded Inconel 625 and 718 showed a strong metallurgical bond at the substrate-clad interface. Columnar and equiaxed dendritic microstructure was observed in the clads. The average microhardness of Inconel 625 and 718 clads was 269 HV and 243 HV, respectively. The Inconel 718 clad had a lower wear rate of 2.31×10−3 mm3/Nm compared to the Inconel 625 samples at 2.46×10−3 mm3/Nm. Based on these findings, Inconel 625 and 718 are promising deposition materials for repairing rail crossings by laser cladding.

Item

Simplifying verifiable credential systems: A hybrid blockchain-based architecture for credential issuance and verification

(2026-07) Kanjere, Julian S; Ford, Merryl; Mutemula, Edzani B

Verifiable credentials (VCs) enable trusted issuers to provide cryptographically verifiable digital credentials to holders, which can later be presented to verifiers without relying on centralised authorities. Despite their conceptual advantages, real-world deployment of VC systems remains challenging due to infrastructure complexity, usability barriers, fragmented standards, and the need for specialised technical expertise. This paper presents a simplified hybrid credential system that supports credential issuance and verification on a blockchain through RESTful APIs. The system consists of a credential service that interacts with a smart contract deployed on the Polygon blockchain test network and a web-based credential management application that manages the lifecycle of issuing, holding, and verifying credentials. To improve usability, an issued credential is delivered to a holder as a PDF document via email. This PDF contains a record of the corresponding blockchain transaction and a QR code for verification. We describe the design and implementation of the system and present initial benchmarking results. Experimental evaluation shows average issuance and verification times of approximately 4 seconds and 0.4 seconds via the API workflow, and 5 seconds and 0.7 seconds via the web-based workflow, indicating practical performance for real-world deployments. Future work will focus on performance optimisation, privacy-preserving credential mechanisms, credential revocation and alignment with verifiable credential standards.

Item

Leaf spectroscopy reveals post-fire phenolic chrono sequence in the Fynbos biome

(2026-08) Sibiya, Sihle B; Cho, Moses A; Mutanga, O; Odindi, J; Masemola, Cecilia; Van Stade, J

Fire is a key physical driver of ecosystem change, while plants rely on secondary metabolites such as phenolic compounds for chemical defense. Despite their importance, fire effects on secondary metabolites are often studied separately. Consequently, the mechanisms by which post-fire conditions shape the levels and diversity of secondary compounds in plant communities remain poorly understood. In this study, we used leaf spectroscopy to investigate how post-fire affects secondary metabolites in the fire- driven fynbos biome, a system rich in secondary metabolites. Results showed that both fire and secondary metabolites contribute to ecosystem rejuvenation. Areas subjected to recent fires in 2015, 2016, and 2021 exhibited high phenolic levels, whereas regions with limited fire in 2010 or no recent fire (“never_exp”) had low phenolic concentrations. Using continuum removal, we identified the strongest spectral features for total phenols at 1660 nm and for flavonoids at 415 nm. Because chlorophyll also absorbs strongly in the 410–430 nm region, we evaluated and adjusted multiple spectral indices to improve flavonoid sensitivity. The Flavonoid Index (FI)415,710 and FI420,710 showed the strongest relationships with phenolic content (R flavonoids: R 2 = 0.55; RRMSE ≈ 1.98– 1.99%). Phenolic concentrations were also estimated using random forest regression. Prediction of total phenols was generally more accurate than flavonoids (total phenols: R 2 2 = 0.82, RRMSE = 12.54%; = 0.81, RRMSE = 10.75%). Total phenols were best modeled using short-wave infrared (SWIR) spectra, while flavonoids were best modeled using full (VSWIR) spectra. Overall, our findings clarify the coupled roles of fire and secondary metabolites in supporting fynbos resilience and regeneration.