Browse
Recent Submissions
Item Measurement of phase transition, density and viscosity of supercritical carbon dioxide-Fischer-Tropsch wax mixtures2025(2025-06) Swanepoel, Andri; Labuschagne, Philip W; Schwarz, CEMelting temperature, phase behaviour and densities of binary mixtures of CO 2 and three Fischer-Tropsch waxes with varying molecular weights were experimentally determined. The melting temperatures of the lower molecular weight waxes increased with CO 2 pressure, and pressure induced crystallisation of the lowest molecular weight wax occurred above 20 MPa. CO 2 solubility in the waxes decreased with increasing wax molecular weight. Trends in mixture densities with changes in temperature and pressure mimicked that of pure CO viscosity of the lowest molecular weight wax decreased with increased CO 2 2 . The concentration, and decreased with increases in temperature and pressure, with the impact of pressure minimised above the temperature inversion point. Solubility data were correlated with a modified Chrastil and the Mendez-Santiago & Teja models. The Chrastil model accurately predicted solubility of CO 2 in all three waxes to within 1 % of the measured values.Item Effect of Cowpea Lignocellulosic Fibers as a Low-Value Reinforcing Filler on the Properties of Poly(butylene succinate-co-adipate) Bio-Composite Foams(2025-03) Masanabo, MA; Keränen, JT; Ray, Suprakas S; Emmambux, MNHerein, fully bio-based and biodegradable bio-composite foams are produced from poly(butylene succinate-co-adipate) (PBSA), reinforced with low-value , and azodicarbonamide as a chemical blowing agent. These are produced by melt extrusion followed by compression molding. Fiber addition increases the melt viscosity and melt strength, this restricts uncontrolled bubble growth during foaming to decrease the bubble size. The bio-composite foam containing 15% fibers has the largest decrease in bubble size from 209 μm in the unfilled PBSA foam to 95 μm in the foam containing 15% fibers. Fiber addition significantly increases the bubble density, from ≈1.05 × 109 cells cm−3 in the unfilled PBSA foam to 5.13 × 109 cells cm−3 in bio-composite foam containing 15% fibers, due to heterogeneous bubble nucleation induced by the fibers. The stiffness of the bio-composite foams increases with fiber addition, with the bio-composite foam containing 15% showing the largest increase relative to the unfilled PBSA foam as revealed by dynamic mechanical analysis. In conclusion, the f ibers not only induce heterogeneous bubble nucleation to increase bubble density and decrease bubble size during the foaming of PBSA, but also act as reinforcement to increase the stiffness of the bio-composite foams. These bio-composite foams have potential applications in packaging and agriculture.Item Sustained gamification in medication adherence: Strategies and conceptual framework(2025-03) Adetunji, RO; Botha, Adele; Herselman, Martha EThis paper examines the current body of literature on medication adherence using sustained gaming strategies and approaches. The objective is to investigate the concepts of sustained gaming, gaming strategies, and gaming approaches in relation to medication adherence. The goal is to identify the elements that contribute to a conceptual framework for understanding medication adherence behavior in patients, as part of a broader study. A comprehensive literature review was performed on four scholarly databases: MEDLINE, BMC, Global health, and Embase. The study examined the strategies and methodologies employed by the Pokémon Go game as a location-based game (LBG), and its impact on patients' adherence to medication. The study has identified several components, namely physical activities, social connections, exploration, enhanced emotional expression, and Marlien Herselman Council of Scientific and Industrial Research, Pretoria South Africa Technology for Development (ICT4D) viewpoints should encompass various aspects, including economic, ecological, educational in nature, political, cultural, and technological dimensions [10-12]. The concept of sustainability has gained significant attention in the field of Information Systems [8, 13] while the concept of long-term gaming strategies and approaches is seldom addressed and has yet to be thoroughly examined in scholarly literature. Furthermore, there is a lack of theoretical research that specifically examines the use of strategies and approaches for sustained gaming in relation to medication adherence. This article aims to identify the strategies, approaches, and gaming experiences that promote sustained gaming in order to develop a conceptual framework for medication adherence in patients focusing on Pokémon Go as a game. This study adds to the growing body of knowledge in the field of digital health, gaming and medication adherence. individual/self-treatment. The study conducted a qualitative examination on Pokemon Go players to understand their experiences and what kept them playing the games for a longer period. Therefore, the findings from the study and data analysis helped in the development of conceptual framework for promoting medication adherence using sustained gaming strategies and approaches is hereby presented. The results of this study have the potential to contribute to a shared comprehension among practitioners, professionals, and academics in the field of digital health and serious games. Additionally, these findings can serve as a foundation for future research on the long-term viability of digital health through gaming.Item Assessment of the inland wetland ecosystem types in South Africa: threats and protection(2025-04) Van Deventer, Heidi; Nel, JLEcosystem threat status (ETS) and ecosystem protection levels (EPLs) are headline indicators that can assess freshwater ecosystems at a country-wide scale. A spatial layer of freshwater, inland wetland ecosystem types of South Africa was combined with a range of spatial data sets to model their ecological condition. The ETS and EPL of each ecosystem type were determined using the area of that type in good ecological condition relative to a biodiversity target, which represented 20% of the total area of that ecosystem type. Thresholds were applied to distinguish four ETS categories ranging from Least Concern to Critically Endangered, and four EPL categories ranging from Not Protected to Well Protected. A total of 79% of the 135 of South African inland wetland ecosystem types were found to be threatened, of which 83 (62% of the number of types) are Critically Endangered, 12 (9%) are Endangered, 12 (9%) are Vulnerable and 28 (21%) of Least Concern. Of the 135 inland wetland types, 61% were Not Protected, with 6% being Well Protected, 3% Moderately Protected, and 30% Poorly Protected. Protected and Ramsar sites hosted only 7% of the total area of inland wetlands, which means that the Aichi Biodiversity Target 11 for 2020 (17%) was not met.Item Characterization of ZrC-V-Ti-ZrC multilayer hydrogen storage thin films prepared by e-beam evaporator(2025-05) Rampai, MM; Mtshali, CB; Nemukula, E; Seroka, Ntalane S; Khotseng, LIn this study, a physical deposition method was used to prepare a ZrC–V–Ti–ZrC multi-layered stack film that was deposited on Ti and borosilicate glass substrates. The hydrogenation was achieved by thermal annealing of samples at temperatures of 200, 300, 400, and 550 °C in a pure hydrogen environment with a flow rate of 100 sccm for 30 min. RBS revealed that the multilayers are thermally stable, showing no sign of intermixing of layers up to 600 °C. It revealed the presence of oxygen in all the layers with a significant amount. ERDA revealed that a significant amount of H was near the surface and dropped towards the bulk of the samples, which is the middle layers (V and Ti layers) location. The probing towards the inner last layer (buried ZrC layer) of the multilayer stack showed an increase in the H amount detected. H amount decreased as the oxygen amount was increased in the layers indicating the negative impact of oxygen in the system, such that the total H amount in the samples with the TiO (1:1) and VO (1:1) was 99.122 at.% at 200 °C while that of Ti2O3 (2:3) and V2O3 (2:3) was 60.016 at.% at 300 °C indicating a significant change. The optimum temperature for the highest H amount observed was found to be between 200 °C and 300 °C. The as-deposited sample only showed the surface H, which is normally due to the atmosphere's hydrocarbons. The Raman spectroscopy results indicated that there was a significant decrease in the intensity of the D and G peaks due to annealing in a hydrogen environment. This suggests that the extent of hydrogen absorption, which occurs predominantly in the temperature range of 200–300 °C, is inversely related to the intensity of the D and G peaks. There was more formation of the sp3 at temperatures between 200 °C and 400 °C in the samples as seen by the decrease in the sp2/sp3 ratio from 0.13 to 0.003. XRD revealed the presence of diffraction phases, i.e., ZrC (111), ZrC (400), V2O5 (001), Ti (100), Ti (101), and Ti (103) in addition to the TiH2 and the broadening of peaks for the system annealed at 200 °C and 300 °C due the high H amount, which is consistent with ERDA results. These results indicate the suitability of this system in hydrogen storage applications, provided it is optimized by eliminating oxygen contamination.Item Analytical analysis of the beam propagation factor of elegant Hermite-Gaussian and elegant Laguerre-Gaussian beams with astigmatism(2023-09) Mabena, Chemist MThe impact of astigmatism on the beam propagation factor (M2) of elegant Hermite–Gaussian and elegant Laguerre–Gaussian beams is examined. We derive closed-form expressions for M2 when the optical beams are aberrated with astigmatism. The analysis shows that the beam radius is crucial to the degree of impact astigmatism has on M2. To this extent, we derive the beam radius that separates the region where the M2 is negligibly affected and the region where it becomes severely affected. For the elegant Laguerre-Gaussian beams, we establish a parameter that determines a set of beams that are impacted equally by astigmatism. The analytical results are validated with numerical simulations.Item Mapping the Orientation and Distribution of Defects for the Natural Casting of 2,4,6-Trinitrotoluene (TNT) in 10kg Anti-tank Landmine Mold(2025-03) Thungatha, Lamla; Nyembe, N; Qhamakwane, Tshepo A; Mahlase, Andrew C; Ngcebesha, Pholisa2,4,6-Trinitrotoluene (TNT) is an explosive that is well known for its stable nature, performance, and reliability. It is used in the military and mining industries as it can be cast into various shapes due to its ease of processing at its melting temperature of 80 to 82°C. It can be processed safely within melting temperature without the risk of thermal and impact-related initiation. Despite these properties, casting defect-free charges of uniform density is challenging. Hence, there is a need for targeted quality control measures and process optimisation to minimise density variations and defect formation in manufacturing. In this work the defects formation is mapped for a 10 kg anti-tank landmine, this is done by melting and casting TNT into a 10 kg anti-tank landmine fibre glass mould without any controlled cooling method. The melting and cooling temperature profiles of the TNT casing process were manually monitored using an infrared camera and the process was simulated using COMSOL Multiphysics. The resulting cast was characterised by Vidisco foXRayzor Digital X-Ray and Irdium-192 (192lr) radioactive source. The findings from this study depicted a dense structure at the mould’s margins compared to the booster centre. The less dense area also showed a high proportion of defects which were attributed to shrinkage during cooling.Item Prediction of the appropriate temperature and pressure for polymer dissolution using machine learning models(2025-02) Dadashi, D; Kaedi, M; Dadashi, P; Ray, Suprakas SThe widespread use of polymer solutions in the chemical industry poses a significant challenge in determining optimal dissolution conditions. Traditionally, researchers have relied on experimental methods to estimate the processing parameters needed to dissolve polymers, often requiring numerous iterations of testing different temperatures and pressures. This approach is both costly and time-consuming. In this study, for the first time, we present a machine learning-based approach to predict the minimum temperature and pressure required for polymer dissolution, correlating molecular weight and chemical structure of both the polymer and solvent and its weight percent. Using a dataset compiled from existing literature, which includes key factors influencing polymer dissolution, we also extracted chemical bond information from the molecular structures of polymer-solvent systems. Six different machine learning algorithms, including linear regression, k-nearest neighbors, regression trees, random forests, multilayer perceptron neural networks, and support vector regression, were employed to develop predictive models. Among these, the Random Forest model achieved the highest accuracy, with R2 values of 0.931 and 0.942 for temperature and pressure predictions, respectively. This novel approach eliminates the need for repetitive experimental testing, offering a more efficient pathway to determining dissolution conditions.Item State-of-the-Art Review: Electronic warfare against radar systems(2025) Reddy, Reeshen; Sinha, SThe electromagnetic spectrum (EMS) is emerging as a sixth battlespace domain in military applications and is essential for wireless communications and remote sensing. Due to the demand for EMS, it is increasingly contested, congested, constrained, and shared. Evolving threats, doctrine, and tactics drive significant advancements in the battlespace. Electronic Warfare (EW) or Electromagnetic Warfare products need to keep pace by leveraging advances in technology driven by Industry 4.0, artificial intelligence (AI), direct radio frequency (RF) sampling, RF System on Chip (RFSoC), and ultrawideband antenna arrays. These trends drive a need for technology-intensive innovation in EW products underpinned by a coherent business-product-technology strategy. This article reviews advancements in Electronic Warfare against radar systems using a novel approach that integrates quantitative bibliometric and patentometric analyses with a qualitative assessment of EW architectures, Electronic Attack (EA) algorithms, and Electronic Support (ES) algorithms. This article marks the first instance of such a methodology being applied to systematically assess the landscape of research publications and technological innovations in the field of EW against radar systems. A taxonomy of EW System Types by military domain against radar and their role in the modern battlefield is presented together with their typical role and real-world examples. The quantitative and qualitative insights are synthesized to outline a notional next-generation EW architecture and a technology roadmap for its realization that researchers can use to guide the development of innovative EW technologies and methodologies and by EW practitioners to inform system design, operational deployment, and capability enhancements.Item Conserving cross-realm coastal biodiversity when real-world planning and implementation processes split the land and sea(2025-04) Harris, LR; Van Niekerk, Lara; Holness, SD; Sink, KJ; Skowno, AL; Dayaram , A; Van Deventer , Heidi; Job, N; Lamberth , SJ; Adams, JB; Raw, JL; Riddin, T; MacKay , CF; Perschke, MJConservation planning and implementation are typically applied in land and sea areas separately, placing already impacted coastal biodiversity – which spans the divide – at risk of being inadequately managed and conserved. In South Africa, we tested how well existing land-based and marine biodiversity priority areas cover coastal priorities that we identified cross-realm using Marxan with >1000 biodiversity features. Existing priorities covered 83% of coastal priorities, indicating good but incomplete coverage. Proportionately, the seashore (foredunes, shores) and estuaries had greatest selection as coastal priorities, confirming their important biodiversity value. Finally, we developed a map of Critical Biodiversity Areas for the South African seashore and estuaries, with management recommendations. To include coastal biodiversity in real-world planning, we propose: co-developing data and targets for cross-realm features; identifying broad coastal priorities that can be used in land-based and marine plans; and developing dedicated seashore and estuary priorities to seamlessly align land-based and marine prioritisation maps.Item Geospatial data quality training for the South African Spatial Data Infrastructure – Lessons learnt from training geospatial data custodians(2025-03) Cooper, Antony K; Fourie, Nicolene MR; Coetzee, S; Blom, M; Chauke, M; Ndlovu, VStandards play an important role in achieving the objectives of a spatial data infrastructure. However, standards can be difficult to understand and implement for those with limited exposure to them. The South African Spatial Data Infrastructure (SASDI) aims to facilitate the capture, management, maintenance, integration, distribution and use of spatial information. To decide whether a SASDI data set is fit for a specific purpose, users need information about its quality. SANS 19157:2014, Geographic information – Data quality, specifies how the quality of geospatial data can be described and assessed. The Committee for Spatial Information (CSI), responsible for implementing SASDI, identified the need to train geospatial data custodians in implementing SANS 19157. While custodians were eager to learn, several barriers prohibited presentation of training in a ‘traditional’ classroom setting. These barriers included the costs and time to travel from remote areas of the country to a training venue and challenges with scheduling the training at a time suitable to all participants. Online training was therefore delivered − however, structured in a way to overcome general ‘online fatigue’ after the pandemic. In this paper we present our experiences in presenting training on SANS 19157 to professionals responsible for geospatial data sets. We also share the lessons learnt from the novel structure for online training.Item Remote sensing monitoring of soil moisture for South African wetlands(2025-04) Van Deventer, Heidi; Naidoo, L; Apleni, P; Le Roux, J; Blaauw, Ciara; Nel, Willem AJ; Tema, Thabo HSurface soil moisture is an essential climate variable (ECV; https://gcos.wmo.int/en/essential-climate-variables/soilmoisture) which is monitored to inform our understanding of changes in the atmosphere and earth. Soil moisture is also an important indicator, in addition to vegetation and soil types, of the presence of a wetland. According to the South African National Water Act, Act 36 of 1998 (RSA, 1998:18), wetlands are defined as ‘land which is transitional between terrestrial and aquatic systems where the water table is usually at or near the surface, or the land is periodically covered with shallow water, and which land in normal circumstances supports or would support vegetation typically adapted to life in saturated soil’. Only the top 50 cm of soil is used for wetland identification and delineation (DWAF, 2005). Therefore, to be able to detect a wetland using soil moisture as an indicator, we should be able to detect and monitor changes in soil moisture up to 50 cm of depth. In South Africa, wetlands make up < 7% of the extent of the land mass, however, we have not detected all our wetlands yet (Van Deventer et al., 2020). Wetlands were also found to be the most threatened realm both globally (IPCC, 2019) as well as in the two South African National Biodiversity Assessments (NBAs) of 2011 (Nel and Driver, 2012) and 2018 (Van Deventer et al., 2019). Detection and monitoring of a wetland’s soil moisture would not only contribute to the improved representation of their extent in the National Wetland Maps of South Africa, but also allow for quantifying changes in extent, health and their hydrological regime (Van Deventer et al., 2021). If these methods can be applied also elsewhere in the world, we can monitor these changes for reporting to global targets of freshwater ecosystems in the Kunming-Montreal Global Biodiversity Framework (GBF; CBD, 2022).Item Chitosan coating loaded with spearmint essential oil nanoemulsion for antifungal protection in soft citrus (Citrus reticulata) fruits(2025-01) Maswanganye, LTC; Pillai, Sreejarani K; Sivakumar, DIn this study, chitosan (CH) was loaded with spearmint (S) essential oil nanoemulsion (EO) to provide antifungal properties during the postharvest storage of soft citrus fruits. (S)-EO (2%) nanoemulsion–CH (0.8%) coatings inhibited 100% of Penicillium italicum and Penicillium digitatum radial mycelial growth and spore germination in vitro. The (S)EO(2%) nanoemulsion–CH coating (0.8%) enhanced the antifungal activity by achieving 100% inhibition of P. digitatum in soft citrus cultivars ‘Nova’ and ‘Tango’ compared to the control in vivo. However, P. italicum decay was reduced to 33% and 18% in ‘Nova’ and ‘Tango’ soft citrus compared to the control. The (S)-EO (2%)-CH nanoemulsion coating system prepared by high shear homogenization showed a particle size of 252.3 nm and zeta potential of +21.6 mV, indicating changes in molecular interactions and structural reorganization between EO and CH. The polydispersity index values indicated a stable system. pH remained acidic, antifungal activity was favored, and the incorporation of the EO nanoemulsion improved the thermal stability of the CH coating. The optical properties showed less transparency and more opacity. Despite cultivar differences affecting host specificity, the study recommends using a 2% (S)EO nanoemulsion–CH (0.8%) coating instead of synthetic chemicals to extend citrus fruit storage life.Item Uncrewed surface vehicles in the Global Ocean Observing System: a new frontier for observing and monitoring at the air-sea interface(2025) Patterson, RG; Cronin, MF; Swart, S; Beja, J; Edholm, JM; McKenna, J; Palter, JB; Parker, A; Addey, CI; Nicholson, Sarah-AnneObserving air-sea interactions on a global scale is essential for improving Earth system forecasts. Yet these exchanges are challenging to quantify for a range of reasons, including extreme conditions, vast and remote under-sampled locations, requirements for a multitude of co-located variables, and the high variability of fluxes in space and time. Uncrewed Surface Vehicles (USVs) present a novel solution for measuring these crucial air-sea interactions at a global scale. Powered by renewable energy (e.g., wind and waves for propulsion, solar power for electronics), USVs have provided navigable and persistent observing capabilities over the past decade and a half. In our review of 200 USV datasets and 96 studies, we found USVs have observed a total of 33 variables spanning physical, biogeochemical, biological and ecological processes at the air-sea transition zone. We present a map showing the global proliferation of USV adoption for scientific ocean observing. This review, carried out under the auspices of the ‘Observing Air-Sea Interactions Strategy’ (OASIS), makes the case for a permanent USV network to complement the mature and emerging networks within the Global Ocean Observing System (GOOS). The Observations Coordination Group (OCG) overseeing GOOS has identified ten attributes of an in-situ global network. Here, we discuss and evaluate the maturation of the USV network towards meeting these attributes. Our article forms the basis of a roadmap to formalise and guide the global USV community towards a novel and integrated ocean observing frontier.Item Progress in high-power and high-intensity structured light(2024) Harrison, Arthur J; Naidoo, Darryl; Forbes, A; Dudley, AStructured light refers to the ability to tailor light in its many degrees of freedom, from the traditional control in time and space to more exotic multi-dimensional control for new forms of light, including vectorial light, toroidal excitations, spatio-temporal vortices, skyrmions, and optical mobius strips to name but a few. While the toolbox for the creation and detection of structured light has advanced tremendously, this has mostly been in the low power regime. More recently, structured light at high-power and high-intensities has emerged, fuelling new science and applications. In this progress report, we showcase the seminal work that has advanced this field, and indicate the open challenges and opportunities that remain.Item Optical biosensors for the detection of human immunodeficiency virus(2025-02) Lugongolo, Masixole Y; Ombinda-Lemboumba, Saturnin; Mngwengwe, Luleka; Mthunzi-Kufa, PatienceOptical biosensors are small diagnostic devices with a biorecognition element linked to a transducer system, which produces an optical signal relative to the analyte concentration. Biorecognition elements are biological substances such as tissues, cells, nucleic acids, antigens, antibodies, and enzymes. They offer a few benefits over conventional analytical techniques owing to their fast detection abilities, high sensitivity, real time analysis, specificity, portability, and cost effectiveness. These characteristics enable optical biosensors to operate efficiently in fields like clinical diagnostics and healthcare, environmental analysis and monitoring as well as biotechnological industry. In the current study, home-built optical biosensor systems; localized surface plasmon resonance and transmission spectroscopy were used to detect HIV. The findings demonstrated that the virus was detected in the presence of the anti-HIV-1 gp120 antibody on the surface of a gold coated sensor chip and photonic crystal sensor chip as shown by the change in transmittance intensity and wavelength shift thus differentiating between the sample with the virus and the one without the virus. These outcomes will contribute towards the development of a multiplex optical biosensing device for the detection of viral infection and viral load as point of care diagnostic platforms for use in resource limited settings.Item The use of bias-corrected climate model projections for bituminous binder selection for the construction of resilient asphalt roads(2024-06) Mokoena, Refiloe; Mturi, G; Mateyisi, Mohau J; Sias, J; Maritz, JohanThe increased frequency of extreme weather events associated with climate change is a growing concern for road authorities, consultants, contractors and end users. Climate change adaptation is not yet incorporated into South Africa’s transport design and planning. Current design methods for asphalt pavements include recently introduced performance-graded (PG) specifications for bitumen. Although the need exists to use future-projected temperature maps in the road industry, the hindrance to this adoption has been extracting the appropriate rising air temperatures from climate model projections. This study focuses on the integration of biasadjusted historical and projected climate model temperature outputs between 1980 and 2060 to estimate changes in pavement temperatures throughout South Africa to inform a strategy for adaptive material selection. Differences in bitumen selection are observed for the PG 58 and PG 52 maximum temperature grade, and an introduction of PG 70 regions, as derived from climate model data in comparison with the SATS 3208 technical standard. The general trend is a gradual increase in maximum pavement design temperatures, mostly affecting the country’s northern and central regions and corresponding road networks. This paper concludes that adjustments are required regarding climate projections for use in bituminous binder selection based on the current specification.Item Establishing in vitro screening protocols based on phenotypic plasticity of Amaranthus dubius and Galinsoga parviflora seeds for drought, salinity, and heat tolerance(2024) Areington, CA; O’Kennedy, Martha M; SershenThe vulnerability of commercial crops under a changing climate has led scientists to consider wild crop species as alternative food sources. The aim of this study was to identify plastic physiological and morphological traits that could be used to in vitro screen Amaranthus dubius and Galinsoga parviflora seeds for drought, salinity, and heat tolerance. To establish the lethal dose/temperature, 50% (LD/T50), for each stress, seeds for both were subjected to various mannitol and NaCl stresses and a range of temperatures. Percentage seedling emergence was selected as the initial indicator of tolerance and used to establish the LD/T50 for in vitro screening for both species. Seeds of both were then screened at the LD/T50 concentrations/temperatures established, and seedlings that emerged after 21 days were measured for leaf area, root (RL), shoot length (SL), chlorophyll content (Chl), fresh, dry mass, and leaf number. Data for these were used to quantify plasticity in terms of Valladares’s phenotypic plasticity index. For A. dubius, three (viz. RL, SL, and Chl) showed some plasticity (≥0.53) and tolerance across all three stressors. For G. parviflora all traits except SL showed some plasticity (≥0.58) and tolerance across all three stressors. Both species had high phenotypic plasticity across all three stressors, which suggests that wild leafy vegetables may possess the ability to tolerate climate change-associated stressors and should be considered for future breeding programs.Item Theoretical analysis of on-axis obstructed Laguerre-Gauss beams(2024) Mabena, Chemist AAdvances in the generation of structured light beams have led to their increased adoption in various applications such as laser-based material processing, optical microscopy, and optical communication. However, the reliability of these beams, particularly Laguerre-Gauss beams, further hinges on their resilience against damage caused by obstructions. In this work, the self-reconstruction of Laguerre-Gauss beams upon on-axis obstruction is analyzed by modeling the obstructed beam in terms of two orthogonal components–one component representing the attenuated beam and another representing the perturbation by the obstruction. Due to the orthogonality of the two components, the perturbation term is reminiscent of harmonic distortion in signal processing. This approach provides a simple method to quantify the damage via the modal cross-talk generated by the obstruction. To this end, closed-form expressions are derived to calculate the modal spectrum and the total damage caused by the obstruction. The results show that amplitude-obstructed Laguerre-Gauss beams self-reconstruct in the central region. The reduced intensity of the outer rings is shown to be due to the attenuated component being out of phase with the perturbation component. In the case of an on-axis obstruction with phase perturbation, the beam suffers more damage in certain parameter windows and may become reshaped. The results of this work provide a tool that could inform design methods and strategies in applications of structured light.Item Insights on who funds climate change adaptation research in South Africa(2025-02) Mantlana, Khanyisa B; Nondlazi, Basanda X; Naidoo, Sasha; Ramoelo, ABackground: This article examines the funding landscape of climate change adaptation research in South Africa to understand the origin, distribution, and thematic prioritization of funding for climate change research in South Africa. Methods: The article used specific search terms to query peer-reviewed publications in the Web of Science and Scopus databases (1985 to 2023). Results: Environmental Science emerged as the most dominant research area during this period, while Agriculture appeared in the top four positions among research areas in climate change adaptation research in South Africa in both databases. The largest number of publications on climate change adaptation research in South Africa is generated through domestic funding, followed by the United States, the United Kingdom, and Germany. The National Research Foundation (NRF) had the highest number of publications. The analysis revealed a strong paucity of funding relationship between South Africa and other African countries in the field of climate change adaptation research. Conclusions: Knowledge of these trends can inform policy decisions on funding of climate change adaptation in South Africa and strategic partnerships between South Africa and the rest of the world.