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    Thermocatalytic decomposition of methane to low-carbon hydrogen using LaNi1-xCuxO3 perovskite catalysts
    (2024) Duma, Zama G; Swartbooi, Ashton M; Musyoka, NM
    The thermocatalytic decomposition (TCD) of methane is an attractive alternative to produce low-carbon hydrogen and solid carbonaceous materials. In this study, substituted LaNi1-xCuxO3 perovskite catalysts prepared via self-combustion method were investigated for methane TCD. The effect of Ni partial substitution with Cu, varying gas hourly space velocity, temperature and stability on methane conversions were evaluated. PXRD, H2-TPR, SEM-EDS, TGA, and XPS were used to characterize the catalysts. An increase in Cu loading to 50%, increase in temperature and decrease in GHSV resulted in an improvement in methane conversions to 92%. At a GHSV of 2400 ml/gcat.h, no significant deactivation was observed as the stability of the LaNi0.5Cu0.5O3 catalyst increased from 6 to 20 hours’ TOS with methane conversions maintained at 92% where carbon nanofibers were observed on the surface of the spent catalysts. The study demonstrates the potential to prepare LaNi1-xCuxO3 catalysts and identify optimal testing conditions for the novel production of low-carbon hydrogen with minimal catalyst deactivation.
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    Reactively processed poly(butylene adipate terephthalate) composite–based multilayered films with improved properties for sustainable packaging applications: structural characterization and biodegradation mechanism
    (2024)
    In this study, it is attempted to enhance the properties and biodegradability of poly(butylene adipate terephthalate) (PBAT) using nanocomposite technology to meet the demand for sustainable packaging applications. Two nanoclays containing PBAT composites are reactively processed and integrated into the multilayered films. Reactive processing facilitates the dispersion and distribution of nanoclay particles in the PBAT matrix. The multilayered films comprising reactively processed PBAT composites exhibited a 24.5%–31.5% reduction in the oxygen transmission rate and improved dimensional stability and tensile properties. Moreover, the degradability of the multilayered film comprising reactively processed PBAT composites reached 82% in 180 days. In contrast, a neat PBAT film of similar thickness attained only 53% degradation in the same period. The biodegradation mechanism is proposed based on the topology of the disintegrated films studied using scanning electron microscopy, chemical bond vibrations determined by Fourier-transform infrared spectroscopy, and structural evolution by small and wide-angle X-ray scattering (SWAXS). The SWAXS analysis is used to understand the changes in the degree of crystallinity, long-range periodic order, and crystalline and amorphous layer thickness of the multilayered films before and after degradation. Such multilayered films can find applications where packaging or biomedical devices cannot be recycled.
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    Algae infused enhancement of PBAT stiffness: Investigating the influence of algae content on mechanical and thermal properties
    (2024) Letwaba, J; Motloung, Mpho P; Muniyasamy, Sudhakar; Mavhungu, L; Mbaya, R; Okpuwhara, R
    This study investigates the impact of algae loading on the properties of PBAT/algae bio-composites produced through a melt extrusion process. The integration of algae as a filler demonstrated a reinforcing effect on the PBAT matrix,leading to an increase in modulus with higher algae loading. Concurrently, the tensile strength and maximum tensile strain of PBAT decreased with an increase in algae content. The thermal stability of PBAT was affected by adding algae, resulting in bio-composites exhibiting an intermediate behavior compared with their neat precursors. The optimal formulation is achieved with 20 wt.% of algae incorporated into the PBAT matrix. The produced PBAT/algae bio-composites, demonstrated versatile applications across a wide range of products.
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    Localized surface plasmon resonance optical biosensor for simple detection of deoxyribonucleic acid mismatches
    (2024) Lugongolo, Masixole Y; Ombinda-Lemboumba, Saturnin; Hlekelele, Lerato; Nyokana, Nontsikelelo; Mthunzi-Kufa, Patience
    Optical biosensors are optical technologies that evaluate changes in the refractive index as they monitor non-covalent molecular interactions in real time. These make use of unsophisticated, label-free analytical approaches, which do not require dyes to produce a visible signal. In this study, the efficiency of localized surface plasmon resonance (LSPR) biosensor in detecting a single nucleotide mismatch in deoxyribonucleic acid is examined. The detection is based on the hybridization of a target DNA at 100 ng μL−1 with a complementary biotinylated probe as well as a partially complementary biotinylated with one nucleotide mismatch probe on a gold-coated surface. Both probes are used at a concentration of 0.1 μm. The LSPR exhibited sensitivity by differentiating sample M+ from sample C+ through varying transmission intensities of 0.28 and 0.26 μA, respectively. Based on these findings, this approach demonstrates a great potential due to its ability to distinguish samples that differ with a single base pair, and its efficiency will be explored in the development of a point-of-care device as a simpler and cost-effective approach for detection of various biologically and medically significant mutations such as antimicrobial resistance mutations. More work is underway to determine the robustness of the LSPR biosensor using the biotin–neutravidin approach.
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    Melt-extruded high-density polyethylene/pineapple leaf waste fiber composites for plastic product applications
    (2024) Khumalo, MV; Sethupathi, M; Skosana, SJ; Muniyasamy, Sudhakar
    This study examines the impact of Pineapple Leaf Fiber (PALF) loading on the properties of High-Density Polyethylene (HDPE)/PALF composites successfully produced through a melt extrusion process. The melt-extruded HDPE/PALF composites were characterized by their thermal and mechanical properties and their morphologies. Subsequently, adding 5% maleic anhydride (MA) to the HDPE/PALF composite formulation led to significant improvements in the mechanical strength properties. Moreover, adding 10 wt.% PALF and 5% MA to the composites improves the crystallinity (10.38%) and Young’s modulus (17.30%) properties and affects the thermal stability. The optimal formulation is achieved with 10 wt.% PALF filler incorporated into the HDPE composite. This study highlights the promising potential of HDPE/PALF composites for plastic product applications.
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    Development of Best Practice Guideline for the management of hot holes in surface coal mines
    (2024) Mpofu, Mvikel; Maphalala, M; Kgarume, Thabang E; Magweregwede, Fleckson T; Stenzel, G
    Surface coal operations in which mining activities are conducted above old underground workings experience hot holes after drilling. In a coal mine, hot holes are defined as shot holes, which after being drilled have an in-hole ambient temperature of 40°C or above or show a temperature increase of 3°C or more during monitoring. Hot holes and other cavities, such as cracks, pose health and safety risks to workers, such as exposure to hot air and high concentrations of noxious gases released from these holes. In addition, workers may be exposed to premature detonation of explosives caused by in-hole temperature increases and chemical reactions. To this end, Coaltech Research Association commissioned a project to develop a Best Practice Guideline for the management of hot holes. This paper is a compilation of the activities conducted in the development of the Best Practice Guideline between 2021 and 2022. The activities included a review of standard operating procedures and hot-hole temperature-measuring and -monitoring devices, and the assessment of current hot-hole procedures at selected mines. The results indicated that management of hot holes requires a focus on pre-emptive risk assessment of mining blocks, identification of hot holes using the correct temperature-measuring devices, and continuous monitoring of hot holes from the time of drilling until just before blasting. Hot-hole management accessories, such as polyvinyl chloride sleeves, were found to be effective in insulating the hot-hole emulsion from the rock mass temperature, thus preventing the potential for premature detonation.
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    Mapping weed infestation in maize fields using Sentinel-2 data
    (2024) Mkhize, Yoliswa; Madonsela, Sabelo; Cho, Moses A; Nondlazi, Basanda X; Main, R; Ramoelo, A
    Weed management in maize farms is a time-specific activity and requires timely detection of weed infestations. The challenge to early detection of weeds is that many dicotyledonous crops and broad-leaved weeds often display similar reflectance profile in the early growth stage and requires hyperspectral data to detect them. However, the advent of Sentinel-2 sensor series, with enhanced spectral configuration featuring red-edge bands that are known for species-level discrimination of plants, presents an affordable opportunity to detect weeds using multispectral data. The present study explores the question of whether Sentinel-2 sensor with its advanced spectral configuration can differentiate weeds from maize (Zea mays) in the early growth stages of maize. The study recorded 165 GPS points of weeds, maize, and mixed class in six maize farms during the early stages of maize growth. These GPS points were overlaid on Sentinel-2 images acquired within two days of field data gathering to guide the collection of spectral signatures of the maize, mixed, and weed classes. Spectral signatures were divided into training (70%) and validation (30%) data in a Random Forest (RF) model with S-2 spectral bands and vegetation indices as predictor variables. Spectral signatures were firstly tested for spectral separability between classes using ANOVA. The results of spectral analysis showed that the weed class had higher interclass variability from the maize and mixed class particularly in the red-edge and NIR regions of Sentinel-2. The classification matrix consistently showed that weeds were detected with high user and producers’ accuracy of 95%. These results indicate the utility of the enhanced spectral configuration of Sentinel-2 data in the early detection of weeds in maize farms.
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    Recent advances in the development of multiplexed nanophotonic biosensors
    (2024) Mcotshana, Zenande KS; Thwala, Nomcebo L; Tlomatsane, Moratoa HC; Van Steen, E; Mthunzi-Kufa, Patience
    The field of nanophotonics has advanced and can be utilized as a method to detect different infectious diseases. The introduction of multiplex nanophotonic diagnostics has enabled the speedy and simultaneous detection of viral infections and specific biomarkers. The quick reaction times, high sensitivity, and specificity of multiplex nanophotonic diagnostics enable real-time identification of viruses without the need for nucleic acid amplification. This review presents an overview of nanophotonic tools used to identify diseases and particular biomarkers. The paper also examines possible research areas for the development of unique, cutting-edge multiplex nanophotonic diagnostics capable of concurrently detecting various diseases or biomarkers/biomolecules. Furthermore, it discusses barriers to further advancement and offers insight into anticipated trends.
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    Assessing the extent to which African wetland inventories can report to the global targets on biodiversity, including Goal A of the Global Biodiversity Framework
    (2024) Sadiki, MM; Van Deventer, Heidi; Hansen, CD
    Wetlands face global threats with estimates suggesting a loss ranging from 21% to 85% of their original extent. Africa’s wetlands, covering about 4.4% of the continent, provide crucial services to millions of people and harbour significant biodiversity. This study assesses African countries’ readiness for the Kunming−Montreal Global Biodiversity Framework (GBF) through wetland inventories. It examines the progress made under the Aichi Targets for 2020, revealing 39% of reporting African countries indicating being on track for Aichi Target 11. Subsequently, the study explores wetland inventorying trends from national reports made to the Ramsar Convention from COP07 (1999) to COP14 (2022), showcasing increased membership and progress in African countries. Notable patterns emerge, revealing challenges in maintaining accurate inventories. Despite varying responses, 67% of African countries reported having a comprehensive wetland inventory at one point in the past 23 years. However, the wetland inventories are out of date, and critical information is not easily accessible, hampering accurate reporting on the current state of wetlands, and hindering informed decision-making for conservation and protection initiatives. Global datasets have contributed to reporting on wetland ecosystems; however, biodiversity-focused wetland typology systems like the IUCN Global Ecosystem Typology are crucial for a comprehensive understanding of wetland ecosystems.
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    Exploring the usefulness of the INLA model in predicting levels of crime in the City of Johannesburg, South Africa
    (2024) Coleman, Toshka; Mokilane, Paul M; Rangata, Mapitsi R; Holloway, Jennifer P; Botha, Nicolene MR; Koen, Renée; Dudeni-Tlhone, Nontembeko
    Crime prediction serves as a valuable tool for deriving insightful information that can inform policy decisions at both operational and strategic tiers. This information can be used to identify high-crime areas, and optimise resource allocation and personnel management for crime prevention. Traditionally, techniques such as the Poisson model and regression analysis have been widely used for crime prediction. However, recent statistical advancements have introduced Integrated Nested Laplace Approximations (INLA) as a promising alternative for spatial and temporal data analysis. This study focuses on crime prediction using the INLA model. Specifically, the first-order autoregressive model under the INLA modelling framework is employed on longitudinal data for crime predictions in different regions of the City of Johannesburg, South Africa. The model parameters and hyperparameters considering space and time are estimated through the INLA model. In this work, the suitability and performance of the INLA model for crime prediction is assessed, which effectively captures spatial and temporal patterns. This study contributes to research by first introducing a novel approach for South African crime prediction. Secondly, it develops a model using no demographic information other than clustering attributes as an exogenous variable. Thirdly, it quantifies prediction uncertainty. Finally, it addresses data scarcity through demonstrating how INLA can provide reliable crime predictions, where conventional methods are limited. Based on our findings, the INLA model ranked areas by crime levels, obtaining a 29.3% Mean Absolute Percentage Error (MAPE) and 0.8 value for crime predictions. These findings and contributions presents the potential of INLA in advancing evidence-based decision-making for crime prevention.
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    Making gene editing accessible in resource limited environments: Recommendations to guide a first-time user
    (2024) Goolab, Shivani; Scholefield, Janine
    The designer nuclease, CRISPR-Cas9 system has advanced the field of genome engineering owing to its programmability and ease of use. The application of these molecular scissors for genome engineering earned the developing researchers the Nobel prize in Chemistry in the year 2020. At present, the potential of this technology to improve global challenges continues to grow exponentially. CRISPR-Cas9 shows promise in the recent advances made in the Global North such as the FDA-approved gene therapy for the treatment of sickle cell anaemia and β-thalassemia and the gene editing of porcine kidney for xenotransplantation into humans affected by end-stage kidney failure. Limited resources, low government investment with an allocation of 1% of gross domestic production to research and development including a shortage of skilled professionals and lack of knowledge may preclude the use of this revolutionary technology in the Global South where the countries involved have reduced science and technology budgets. Focusing on the practical application of genome engineering, successful genetic manipulation is not easily accomplishable and is influenced by the chromatin landscape of the target locus, guide RNA selection, the experimental design including the profiling of the gene edited cells, which impacts the overall outcome achieved. Our assessment primarily delves into economical approaches of performing efficient genome engineering to support the first-time user restricted by limited resources with the aim of democratizing the use of the technology across low- and middle-income countries. Here we provide a comprehensive overview on existing experimental techniques, the significance for target locus analysis and current pitfalls such as the underrepresentation of global genetic diversity. Several perspectives of genome engineering approaches are outlined, which can be adopted in a resource limited setting to enable a higher success rate of genome editing-based innovations in low- and middle-income countries.
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    Elucidating the local structure and electronic properties of a highly active overall alkaline water splitting NixCo1-xO/hollow carbon sphere catalyst
    (2024) Mashindi, V; Terban, MW; Motta Meira, D; Moreno, BD; Morongoa, Prettier M; Rikhotso-Mbungela, Rirhandzu S; Marx, G; Olivier, J; Barrett, DH; Moloto, N
    A NixCo1-xO/HCS catalyst with superior water-splitting is presented. High water-splitting reaction kinetics and enhanced durability were observed. The structure-function relationship was investigated with XPS, which demonstrated the presence of dominant Ni2+ and Co2+ species and a functionalized HCS support where nucleation of small metal oxide nanoparticles occurred. The PDF showed broadened Nickel/Cobalt-oxide bonds and expansion of the metal-metal pair distances. The alteration of the Metal-Oxide and Metal-Metal-Oxide bonds favored better HER and OER electrocatalysis, also as supported by DFT. EXAFS showed the existence of the bimetallic oxide catalyst and the stretching of the Ni–O bonds due to the coordination of the Ni–O with the Co. The composite exhibited higher activity and enhanced electrocatalytic mechanism towards water splitting through higher exchange current densities (0.615 and 0.886 mA cm−2) and low charge transfer resistance (14 and 10 Ω) respectively. Chronoamperometry proved the catalyst's stability during prolonged electrolysis.
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    Applications of microfluidics in biosensing
    (2024) Sekhwama, Masindi; Mpofu, Kelvin T; Sivarasu, S; Mthunzi-Kufa, Patience
    Microfluidic devices have become a vastly popular technology, particularly because of the advantages they offer over their traditional counterparts. They have such a wide range of uses and can make complex tasks quite efficient. One area of research or work that has benefited greatly from the use of microfluidics is biosensing, where microfluidic chips are integrated into biosensor setups. There are growing numbers of applications of microfluidics in this area as researchers look for efficient ways to tackle disease diagnostics and drug discovery, which are critical in this era of recurring pandemics. In this work, the authors review the integration of microfluidic chips with biosensors, as well as microfluidic applications in biosensing, food security, molecular biology, cell diagnostics, and disease diagnostics, and look at some of the most recent research work in these areas. The work covers a wide range of applications including cellular diagnostics, life science research, agro-food processing, immunological diagnostics, molecular diagnostics, and veterinarian diagnostics. Microfluidics is a field which combines fundamental laws of physics and chemistry to solve miniaturization problems involving fluids at the nanoscale and microscale, and as such, the authors also examine some fundamental mathematical concepts in microfluidics and their applications to biosensing. Microfluidics has relatively new technologies with great potential in terms of applications.
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    Forthcoming Networks and Sustainability in the AIoT Era
    (2024) Rasheed, J; Abu-Mahfouz, Adnan MI; Fahim, M
    This book introduces a groundbreaking approach to enhancing IoT device security, providing a comprehensive overview of its applications and methodologies. Covering a wide array of topics, from crime prediction to cyberbullying detection, from facial recognition to analyzing email spam, it addresses diverse challenges in contemporary society. Aimed at researchers, practitioners, and policymakers, this book equips readers with practical tools to tackle real-world issues using advanced machine learning algorithms. Whether you're a data scientist, law enforcement officer, or urban planner, this book is a valuable resource for implementing predictive models and enhancing public safety measures. It is a comprehensive guide for implementing machine learning solutions across various domains, ensuring optimal performance and reliability. Whether you're delving into IoT security or exploring the potential of AI in urban landscapes, this book provides invaluable insights and tools to navigate the evolving landscape of technology and data science. The book provides a comprehensive overview of the challenges and solutions in contemporary cybersecurity. Through case studies and practical examples, readers gain a deeper understanding of the security concerns surrounding IoT devices and learn how to mitigate risks effectively. The book's interdisciplinary approach caters to a diverse audience, including academics, industry professionals, and government officials, who seek to address the growing cybersecurity threats in IoT environments. Key uses of this book include implementing robust security measures for IoT devices, conducting research on machine learning algorithms for attack detection, and developing policies to enhance cybersecurity in IoT ecosystems. By leveraging advanced machine learning techniques, readers can effectively detect and mitigate cyber threats, ensuring the integrity and reliability of IoT systems. Overall, this book is a valuable resource for anyone involved in designing, implementing, or regulating IoT devices and systems.
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    Current situation and future prognosis of health, safety and environment risk assessment of nanomaterials in South Africa
    (2023-01) Gulumian, M; Thwala, Melusi; Makhoba, X; Wepener, V
    The commercialisation and everyday use of nanomaterials and nanomaterial-enabled products (NEPs) is rising year-on-year. Responsible development of nanotechnology includes understanding their potential implications on health, safety, and the environment (HSE). The health risk assessment of nanomaterials has therefore become one of the major activities of international agencies including the Organisation for Economic Co-operation and Development and the Environmental Protection Agency for protection of human health and the environment. Nationally, with the foresight and the leadership of the Department of Science and Innovation, a HSE programme was initiated to establish the necessary infrastructure to conduct the tests in the hazard identification and exposure assessment that are needed in the risk assessment of nanomaterials synthesised as well as NEPs available in South Africa. Here we present the advances that have been made in elucidating the different facets that are required when undertaking risk assessments of nanomaterials, i.e. physicochemical characterisation, hazard identification, exposure assessment and effects assessment. These facets are increasingly being considered throughout the nanomaterials present in the life cycles of NEPs. South Africa's research contribution to an international understanding of HSE risks of nanomaterials is highlighted and the future direction to generate the necessary information for effective risk communication and management is provided. This will assist in ensuring safer innovation of nanotechnology in South Africa and support the export of locally manufactured nanomaterials as per international requirements.
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    Sustainable rail/road unimodal transportation of bulk cargo in Zambia: A review of algorithm-based optimization techniques
    (2024-01) Miyoba, F; Mujuni, E; Ndiaye, M; Libati, HM; Abu-Mahfouz, Adnan MI
    Modern rail/road transportation systems are critical to global travel and commercial transportation. The improvement of transport systems that are needed for efficient cargo movements possesses further challenges. For instance, diesel-powered trucks and goods trains are widely used in long-haul unimodal transportation of heavy cargo in most landlocked and developing countries, a situation that leads to concerns of greenhouse gases (GHGs) such as carbon dioxide coming from diesel fuel combustion. In this context, it is critical to understand aspects such as the use of some parameters, variables and constraints in the formulation of mathematical models, optimization techniques and algorithms that directly contribute to sustainable transportation solutions. In seeking sustainable solutions to the bulk cargo long-haul transportation problems in Zambia, we conduct a systematic review of various transportation modes and related mathematical models, and optimization approaches. In this paper, we provide an updated survey of various transport models for bulk cargo and their associated optimized combinations. We identify key research challenges and notable issues to be considered for further studies in transport system optimization, especially when dealing with long-haul unimodal or single-mode heavy cargo movement in countries that are yet to implement intermodal and multimodal systems.
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    Short term ageing of asphalt binder in thin asphalt layers
    (2024-03) O’Connell, Johan; Maina, James; VdM Steyn, WJ
    The effects of ageing on pavement performance are significant, particularly in terms of fatigue cracking. South Africa has the 10th longest road network in the world, requiring innovative approaches to road construction due to severe budget constraints. Innovative solutions such as thin asphalt concrete layers for surfacing, result in unique ageing rates of the layers, which, in general, have a higher incidence of fatigue cracking than, for example, thicker asphalt concrete layers used in other parts of the world. The objective of this paper is to evaluate how ageing mechanisms affect various asphalt binder properties, and whether they affect them to the same extent or not. Furthermore, the objective of the paper is also to determine the accuracy of the Rolling Thin Film Oven Test (RTFOT) in simulating short-term ageing in the field. The RTFOT provides a relatively good indication of short-term ageing, according to this multi-decade ageing study, and the effect on the asphalt binder properties used as ageing indices depends on the specific property chosen for comparison before and after ageing.
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    A survey on low-power wide area networks for IoT applications
    (2024-03) Bembe, M; Abu-Mahfouz, Adnan MI; Masonta, Moshe T; Ngqondi, T
    We are on the entry of the exponential advancement of the internet-of-things (IoT) due to the quick development of internet-connected smart-objects. As the number of connected smart-objects increase, IoT will continue to advance by providing connectivity and interactions between the physical and the cyber world. This connectivity is characterized by low throughput, delay sensitivity, small and wide coverage, low power consumption, low device, etc. Which explains the emergence of low power wide area network (LPWAN). LPWAN technologies are an alternative promising connectivity solutions for Internet of Things. However, the lack of an overall LPWAN knowledge that present a comprehensive analysis of LPWAN technologies is presently constraining the achievement of the modern IoT vision. In this paper, we begin with a detailed analysis of the conventional high power long-range network technologies that considers IoT applications and requirements. We further point out the need for dedicated low power wide area technologies in IoT systems. In addition, we analyse the technical specification based on the PHY and MAC layers of the technologies that are already deployed, or likely to be deployed. The focus is to incorporate both standard and proprietary technologies in our study. Furthermore, we present the modelling techniques and performance metrics that are adopted in LPWAN networks analysis. Finally, challenges and open problems are presented. The main contribution of this study is that it provides an enhanced summary of the current state-of-the-art of LPWAN suitable to meet the requirements of IoT, while uniquely providing LPWAN’s modelling techniques, performance metrics and their associated enablers.
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    Winter entrainment drives the mixed layer supply of manganese in the Southern Ocean
    (2024-07) Ramalepe, Thapelo; Samanta, S; Cloete, R; Ryan-Keogh, Thomas J; Roychoudhury, AN
    Despite the subnanomolar dissolved manganese concentrations that can co-limit Southern Ocean primary production, their physical supply mechanisms during winter, for biological consumption in spring and summer have not yet been explored. During austral winter and spring 2019, two cruises were conducted in the Atlantic sector of the Southern Ocean, to determine the distribution and surface water supply mechanisms of dissolved manganese in the upper water column. The supply mechanisms were used to calculate the total flux of dissolved manganese to productive surface waters and were compared to biological consumption estimates. Mean dissolved manganese concentrations in the upper water column (< 500 m) during winter and spring were comparably low (= 0.34 nmol kg1; p > 0.05), with seasonal mixed layer reservoir sizes averaging 65.21 12.93 and 21.64 19.32 µmol m2, respectively. Winter entrainment contributed 89.33–99.99% (average 97.26% 5.28%) of the total dissolved manganese flux, while diapycnal diffusion contributed 0.52–10.58% (average 4.92% 5.14%), was identified as the dominant mechanisms for transporting dissolved manganese into the mixed layer in the subantarctic zone, polar frontal zone, and antarctic zone. Here, the winter physical supply rates were higher than the estimated consumption rates during spring, meeting phytoplankton biological demands. Whereas in the subtropical zone, the supply rates were lower than the consumption rates, indicating the presence of additional supply mechanisms such as coastal upwelling, which may help to meet the biological demands in this region.
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    Unraveling the interplay between the leucine zipper and forkhead domains of FOXP2: Implications for DNA binding, stability and dynamics
    (2024-05) Perumal, CM; Thulo, M; Buthelezi, Sindisiwe G; Naicker, Previn; Stoychev, Stoyan; Lahki, A; Fanucchi, S
    FOXP2 is a transcription factor associated with speech and language. Like other FOX transcription factors, it has a DNA binding region called the forkhead domain (FHD). This domain can exist as a monomer or a domain swapped dimer. In addition to the FHD, the leucine zipper region (LZ) of FOXP2 is also believed to be associated with both DNA binding and oligomerization. To better understand the relationship between DNA binding and oligomerization of FOXP2, we investigated its structure, stability and dynamics, focusing specifically on the FHD and the LZ. We did this by using two constructs: one containing the isolated FHD and one containing both the LZ and the FHD (LZ-END).We demonstrate in this work, that while the FHD maintains a monomeric form that is capable of binding DNA, the LZ-END undergoes a dynamic transition between oligomeric states in the presence of DNA. Our findings suggest that FOXP2's LZ domain influences DNA binding affinity through a change in oligomeric state. We show through hydrogen exchange mass spectroscopy that certain parts of the FHD and interlinking region become less dynamic when in the presence of DNA, confirming DNA binding and oligomerization in these regions. Moreover, the detection of a stable equilibrium intermediate state during LZ-END unfolding supports the idea of cooperation between these two domains. Overall, our study sheds light on the interplay between two FOXP2 domains, providing insight into the protein's ability to respond dynamically to DNA, and enriching our understanding of FOXP2's role in gene regulation.