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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

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Phosphite inhibits Phytophthora cinnamomi by downregulating oxidoreductases and disrupting energy metabolism

(2025) Prabhu, SA; Naicker, P; Duong, TA; Govender, Ireshyn S; Engelbrecht, J; Backer, R; Stoychev, SH; Van den Berg, N

Phytophthora root rot caused by the hemibiotrophic oomycete, Phytophthora cinnamomi is a major biotic hindrance in meeting the ever-increasing demand for avocados. In addition, the pathogen is a global menace to agriculture, horticulture and forestry. Phosphite trunk injections and foliar sprays remain the most effective chemical management strategy used in commercial avocado orchards against the pathogen. Phosphite is known to counter P. cinnamomi both directly and indirectly through fortification of host defense. However, phosphite's direct mode of action is still not understood completely. This study identified a P. cinnamomi isolate GKB4 sensitive to phosphite (EC50 of 27.9 μg/mL) and investigated the direct impact of phosphite on this isolate through label-free quantitative SWATH-MS. Proteomics data analysis of untreated vs. phosphite-treated samples revealed that the xenobiotic affects the pathogen's growth by targeting the oxidoreductases whose abundance is significantly reduced. Further, perturbations in the energy metabolism and membrane/transmembrane proteins and transporters, and oxidative stress contribute to growth inhibition. The current study also identified increased putrescine biosynthesis, a polyamine, that when present at non-optimal concentrations could be cytostatic/cytotoxic. The differential expression of enzymes involved in the biosynthesis of secondary metabolites and the intermediates/precursors involved in their biosynthesis is an interesting finding that needs further investigation to ascertain their role in phosphite-induced stress. The pathogen's attempt to counter phosphite's growth-inhibitory effects—through upregulation of alternate bioenergetics pathways (amino acid catabolism and β-oxidation of fatty acids), mitochondrial translation and translocation machinery, peroxisomal proteins, and antioxidants—appears ineffective. This research furthers our limited understanding of the direct in vitro effects of phosphite on P. cinnamomi and has identified potential candidates for molecular functional investigation.

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Laser metal deposited Ti4822 hollow pipe: Experimental and computational modelling study

(2025) Raji, SA; Tlotleng, M; Skhosane, Besabakhe S; Kanyane, LR; Popoola, API; Pityana, Sisa L

Generally, manufacturing valuable parts from General Electric's titanium aluminide (Ti-48Al-2Cr-2Nb; Ti4822) is extremely difficult. The difficulty is due to the alloy's poor room temperature castable and machining properties. To achieve functional parts from Ti4822 via cast and selective laser melting, built parts are hot isostatically pressed. Unfortunately, direct energy deposited Ti4822 parts are yet to be reported in open literature and hence this article wherein a 100 mm long pipe is laser metal deposited and investigated for use as a heat exchanger. Before printing, the theoretical model is used to predict geometric defects (tapering) and heat distribution. The results conclude tapering at around 30 mm and rapid increase in heat inputs (HIs). The microstructural analyses corroborated this observation, particularly the fracture analyses which indicated internal cracking, impurities and pores at moderate HI, and isotropic microstructure with elongation formed dimple grains at high HI position. Fracture is said to be transgranular, cleavage-like, and ductile-brittle overall. Nanoindentation results conclude that the pipe would withstand high stress due to high toughness. Pipe inner surface roughness is 5.190 μm, indicating acceptable pressure drops and therefore usable as a heat exchanger.

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Challenges and risks of digitalizing health systems- A review for South African eHealth

(2025-11) Ntshangase, Cynthia S; Mahlasela, Oyena N; Mtshali, Mamello L; Manari, Unarine J; Ledwaba, Lehlogonolo PI; Marengwa, Matshidiso S

This study represents a comprehensive literature review aimed at identifying the challenges and risks associated with the digitalization of health systems. The objective was to assess which healthcare systems are utilized globally and in South Africa. The key digital health systems identified include healthcare management systems, telemedicine, mHealth, electronic health records, cloud, data analytics, wearables, and emerging technologies such as 3D bioprinting, artificial intelligence, and robotics. Recommendations were formulated to promote a balanced approach to health systems digitalization, emphasizing maximizing benefits while mitigating risks and addressing challenges. The recommendations were developed following a review of the identified technologies, focusing on associated risks, challenges, and mitigation measures. Although these technologies enhance healthcare services, they encounter challenges including security issues, limited access, and regulatory compliance. The recommendations propose the enhancement of regulations for compliance and security, with future work concentrating on aligning technologies with South African standards to ensure secure adoption. The findings of this study can assist policymakers and system developers within the Department of Health in South Africa in devising healthcare solutions with minimized risks and challenges.

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Towards a heterogeneous distributed SDN control plane system: A comparative review of open network operating system and open Daylight

(2025-11) Makondo, Ntshuxeko; Mathonsi, TE; Mnyandu, Wandile T; Kobo, Hlabishi I; Du Plessis, DD

The evolution of software-defined networking (SDN) has transitioned from centralized control plane architectures to distributed control plane models, enhancing scalability, reliability, and fault tolerance. While central controllers often face challenges in managing extensive networks, distributed control architectures provide superior performance and flexibility. Initially, homogeneous distributed architectures were prevalent; however, the demand for heterogeneous distributed control planes where controllers interact with diverse systems and components has increased, necessitating advanced coordination and interoperability. This paper compares two widely adopted open-source distributed controllers, the Open Network Operating System (ONOS) and OpenDaylight (ODL), focusing on their methodologies for distributed clustering. It further explores the roles of Atomix and Akka (now Apache Pekko) distributed frameworks in ONOS and ODL, respectively, discussing their impact on performance and scalability. Furthermore, the paper examines the data consistency models used by ONOS and ODL to manage network state and synchronization. Finally, it offers recommendations for enhancing the interoperability and performance of heterogeneous distributed control planes in large-scale and diverse network deployments.

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Perspective Chapter: An overview of titanium dioxide, uses, applications and DFT study of the optoelectronic properties of TiO2 Brookite Clusters

(IntechOpen, 2025) Elegbeleye, I; Mapasha, E; Maluta, E; Maphanga, Rapela R

Titanium dioxide (TiO2) also known as titania belongs to the class of transitions metal oxides. Titanium dioxide has become a metal oxide of fascinating significance in the research sphere due to its numerous environmental and industrial applications. This chapter presents an overview of the physical, crystal, structural and semiconductor properties of TiO2 while delving into direct and indirect band gaps, fermi levels in semiconductors, density of states and carrier concentration. The environmental, pharmaceutical, deodorization, photovoltaic and water purification applications of TiO2 were also discussed. Although TiO2 clusters have become the focus of several computational studies, typical hardware has a higher processing power, giving way for the simulations of cumbersome systems, some cluster sizes used for some studies are relatively small and are not fit to handle specific problems or complex systems significant for photovoltaic applications. First-principle density functional theory calculation using computational software and GPAW that implements electron density represented on real space grids and the projector-augmented wave method were utilized in this study to investigate the optical and electronic characteristics of TiO2 brookite clusters. The results of computational investigations on the optical and electrical characteristics of different-sized TiO2 clusters and intricate systems for the purpose of simulating charge transfer mechanisms in hybrid organic-inorganic photovoltaics and photocatalytic obliteration of contaminants were presented in this chapter.