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Genetic and phenotypic diversity in cannabis genotypes: insights from seed dimensions, mineral profiles, and Short Tandem Repeats (STR) markers
No full textThis study characterized cannabis varieties based on seed physical properties, mineral composition, and Short Tandem Repeats (STR) markers. Eleven cannabis varieties were analyzed, including landraces Ladysmith Ugwayi wesiZulu (‘L1’) and Iswazi (‘L2’), Durban Poison (‘H1’), Bergville Ugwayi wesiZulu (‘B1’), Natal (‘B2’) and Iswazi (‘B3’), and Msinga Ugwayi wesiZulu (‘M1’) and Iswazi (‘M2’), and the commercially available ‘Hemp’, ‘Cherry bubble gum’ (‘High-CBD’) and ‘White Rhino’ (‘High-THC’) varieties. Physical traits measured included seed length, width, thickness, geometric mean diameter, surface area, aspect ratio, and sphericity. Genetic analysis was conducted using sixty-eight STR markers, while mineral composition was assessed using Scanning Electron Microscopy (SEM) with an energy-dispersive X-ray (EDX) detector. Significant differences (p 0.05). Elemental composition varied significantly (p < 0.05), particularly for carbon, oxygen, potassium, phosphorus, sulfur, iron, and silicon. Carbon was highest in ‘High-THC’ (75.10 %) and lowest in ‘H1’ (55.58 %), whereas oxygen showed an inverse trend. Variations in seed dimensions and mineral profiles highlight the diverse genetic and phenotypic landscape of the samples. Positive correlations (p < 0.001) among varieties suggested similarities in physical traits, mineral composition, and STR markers. However, hierarchical clustering revealed distinct groupings, indicating complex diversity. Landraces could not be reliably classified as ‘High-CBD’, ‘High-THC’, or ‘Hemp’, reflecting STR marker neutrality. Integrating STRs with functional gene markers or metabolic profiling may improve chemotype discrimination and support development of cannabis-specific identification tools. These findings provide insights for breeding programs and optimization of desirable traits.Moses Kotane InstitutePlant Gen
A qualitative exploration of managerial mothers' flexible careers: the role of multiple contexts
Get PDFThis study explores the lived career experiences of women managers with children in Sweden. Drawing on existing theory on flexible careers which proposes that multiple contexts – institutional, organizational and individual - shape employees' career decisions, we present findings from a study of 34 career mothers in dual-income households within a large engineering company in Sweden. We show that the institutional context in Sweden, with its shared parental leave, is an important element in the women's career decisions by directly mandating the fathers' engagement with childcare and home roles and indirectly fostering a family-supportive organizational culture. We theorize that the family context needs to be incorporated into existing theoretical models and specifically demonstrate how continuing shared childcare roles between the parents is critical to mothers' career outcomes. We evidence the various ways in which fathers engage with home responsibilities and how that influences the mothers' career decisions. Furthermore, we argue that the institutional environment has consequences which cascade down to each of the other contextual levels and that the importance of the different contexts can vary according to the work-care regime. We therefore challenge recent research which claims that the industry ecosystem is the crucial force in shaping women's careers
Enhancing stationkeeping and motion reduction of floating offshore wind turbines using wave devouring propulsion technology
Get PDFLiyun, Lao - Associate SupervisorThis PhD thesis investigates the enhancement of stationkeeping and motion reduction in
Floating Offshore Wind Turbine (FOWT) platforms through the application of biomimeticinspired
Wave Devouring Propulsion (WDP) technology. Through a multidisciplinary approach
that encompasses a comprehensive literature review, numerical simulations, and
scaled-down water tank experiments, this research confirms the potential of WDP technology
to significantly improve the stationkeeping capabilities of FOWT platforms. The thesis
is structured around four key objectives, each addressing a critical aspect of WDP application
in FOWT platforms—from theoretical underpinnings and simulation tool development
for Fluid-Structure Interaction (FSI) analyses, to the investigation of sub-structure
dynamics and practical feasibility studies for the integration of innovative sub-structures
aimed at stationkeeping. This thesis contributes to the field by providing a comprehensive
overview of WDP technology, introducing a novel numerical model for FSI simulations,
insights into the hydrodynamic performance of submerged hydrofoils, and the experimental
verification of WDP technology’s effectiveness in enhancing platform stationkeeping.
Notably, the study proposes optimized design guidelines for foil implementation, demonstrating
a significant reduction in mooring tension and thereby advancing the practical
applicability of WDP in the marine industry. By advancing the understanding and application
of WDP technology, this thesis lays the groundwork for significant improvements
in the sustainability and efficiency of maritime operations, aligning with global efforts
towards achieving net-zero emissions in the maritime sector.PhD in Energy and Powe
The development of an augmented reality gesture control human-robot interface
Get PDFThere is an increased need for intuitive methods to control and interact with collaborative robot systems that are driven by industries such as manufacturing that involve complex robot operations. Traditional control and programming approaches that involve handheld devices can be both cumbersome and potentially hazardous for operators, as unexpected movements or malfunctions may result in dangerous situations, they also restrict operators’ movements and hinder their ability to respond quickly to changing situations, ultimately slowing down overall operations. The implementation of cutting-edge interface technology such as Augmented Reality (AR) and gesture control can revolutionise robot systems and propel companies towards Industry 4.0. However, a significant gap exists in the realm of user-friendly and dependable AR-based interfaces that seamlessly integrate with robot systems, guarantee safe and precise operations, and reduce the likelihood of operator errors and accidents.This paper demonstrates the benefits of developing and deploying AR gesture interfaces to empower robotics operators to control and interact with manipulators in more natural and efficient manners. This interface could represent a substantial advancement in addressing the problems presented by conventional control methods, ushering in a new era of robot system control and interaction in complex industrial settings.An experimental approach was developed to investigate the feasibility and effectiveness of using AR to control robot systems. A comparative experiment to evaluate the effectiveness and usability of an Augmented Reality (AR) gesture interface, developed using HoloLens 2 and UR16e robot in contrast to the conventional teach pendant control method. The study aims to provide valuable insights into the utility and user-friendliness of the AR gesture interface for robot system control from users’ perspectives. The devices have been compared using participants who have engaged in a series of tasks involving robot movement, manipulation, and interaction.12th International Conference on Control, Mechatronics and Automation (ICCMA
Numerical analysis of crack path effects on the vibration behaviour of aluminium alloy beams and its identification via artificial neural networks
Get PDFUnderstanding and predicting the behaviour of fatigue cracks are essential for ensuring safety, optimising maintenance strategies, and extending the lifespan of critical components in industries such as aerospace, automotive, civil engineering and energy. Traditional methods using vibration-based dynamic responses have provided effective tools for crack detection but often fail to predict crack propagation paths accurately. This study focuses on identifying crack propagation paths in an aluminium alloy 2024-T42 cantilever beam using dynamic response through numerical simulations and artificial neural networks (ANNs). A unified damping ratio of the specimens was measured using an ICP® accelerometer vibration sensor for the numerical simulation. Through systematic investigation of 46 crack paths of varying depths and orientations, it was observed that the crack propagation path significantly influenced the beam’s natural frequencies and resonance amplitudes. The results indicated a decreasing frequency trend and an increasing amplitude trend as the propagation angle changed from vertical to inclined. A similar trend was observed when the crack path changed from a predominantly vertical orientation to a more complex path with varying angles. Using ANNs, a model was developed to predict natural frequencies and amplitudes from the given crack paths, achieving a high accuracy with a mean absolute percentage error of 1.564%.Sensor
Light/ultrasound enhance peroxidase activity of BaTiO3/graphdiyne/Au nanozyme for colorimetric detection of E. coli O157:H7
Get PDFIn the past two decades, nanozymes have garnered increasing interest, however, their catalytic activity and efficacy still lag significantly behind that of natural enzymes, posing limitations on their utility in bioanalytical applications. In this study, we introduced a novel BaTiO3/graphdiyne/Au (BGA) nanozyme that leverages surface plasmon resonance and piezoelectric effects to concurrently respond to light and ultrasound (US) stimulation, resulting in a 3.8-fold enhancement in peroxidase-like activity. Theoretical and experimental findings suggest that US stimulation induces lattice distortion in BaTiO3, leading to the reversible conversion of C[tbnd]C bonds to C[dbnd]C bonds in graphdiyne. Consequently, the liberated electrons recombine with the hot holes produced by Au nanoparticles upon light excitation, thereby efficiently inhibiting the recombination of hot electron-hole pairs and substantially augmenting peroxidase-like activity. The BGA nanozyme was further configured as a detection platform for E. coli O157:H7. The sensor exhibited a broad linear range (1–107 CFU mL−1) and a low limit of detection of 7 CFU mL−1. Moreover, the sensor exhibited exceptional applicability in the analysis of various real samples such as milk and lemon juice. This study presents a novel research framework for constructing high-activity nanozyme sensors responsive to external fields, offering significant potential in biological analysis, environmental surveillance, and food safety applications.National Natural Science Foundation of ChinaThis work was supported by the National Natural Science Foundation of China (Grant No. 22375112), Natural Science Foundation of Shandong Province (Grant No. ZR2021MB111, ZR2020MB026, ZR2023ME076).Sensors and Actuators B: Chemica
Dataset: Coagulation of PFAS data
No full textData showing the removal of PFAS by coagulation under a range of conditions and using different coagulant chemicals
Development of polyvinyl chloride composites with enhanced mechanical properties using modified ceramic particles
Get PDFThe integration of ceramic particles into polyvinyl chloride (PVC) composites offers a promising approach and has garnered significant attention due to their potential for enhancing mechanical properties. This work investigated the development and characterization of PVC composites enhanced with modified ceramic particles. Ceramic particulates, clays, and other mineral rock materials (non-plastics) with activators were processed and incorporated into the PVC matrix at varying weight percentages (5–30 wt%) and particle sizes (40–80 µm). The ceramic–PVC mixtures were synthesized using hot compression molding under specific conditions of 75 MPa pressure and 160 °C temperature. Mechanical properties’ testing was conducted using ASTM D3039 standards, covering flexural, tensile, hardness, and impact tests for comprehensive characterization. Microstructural analysis was performed using scanning electron microscopy (SEM). Results indicated that ceramic reinforcement significantly enhanced the mechanical properties of PVC composites, with notable improvements in flexural strength, tensile strength, hardness, and impact resistance. Moreover, the impact of particle size was crucial, as microstructural analysis revealed improved interfacial bonding between ceramic particles and PVC matrix, particularly with finer particle sizes (40 µm), suggesting better stress transfer. The findings demonstrated that including modified ceramic particles can substantially improve the performance of PVC composites, making them suitable as high-strength construction tiles and impact-resistant flooring.Iranian Polymer Journa
Explainable adversarial learning framework on physical layer key generation combating malicious reconfigurable intelligent surface
Get PDFReconfigurable intelligent surfaces (RIS) can both help and hinder the physical layer secret key generation (PL-SKG) of communications systems. Whilst a legitimate RIS can yield beneficial impacts, including increased channel randomness to enhance PL-SKG, a malicious RIS can poison legitimate channels and crack almost all existing PL-SKGs. In this work, we propose an adversarial learning framework that addresses Man-in-the-middle RIS (MITM-RIS) eavesdropping which can exist between legitimate parties, namely Alice and Bob. First, the theoretical mutual information gap between legitimate pairs and MITM-RIS is deduced. From this, Alice and Bob leverage adversarial learning to learn a common feature space that assures no mutual information overlap with MITM-RIS. Next, to explain the trained legitimate common feature generator, we aid signal processing interpretation of black-box neural networks using a symbolic explainable AI (xAI) representation. These symbolic terms of dominant neurons aid the engineering of feature designs and the validation of the learned common feature space. Simulation results show that our proposed adversarial learning- and symbolic-based PL-SKGs can achieve high key agreement rates between legitimate users, and is further resistant to an MITM-RIS Eve with the full knowledge of legitimate feature generation (NNs or formulas). This therefore paves the way to secure wireless communications with untrusted reflective devices in future 6G.Engineering and Physical Sciences Research Council, UK Research and InnovationThis work is supported by the Engineering and Physical Sciences Research Council: Communications Hub For Empowering Distributed ClouD Computing Applications And Research (CHEDDAR) grant id: EP/X040518/1 and EP/Y037421/1.IEEE Transactions on Wireless Communication
Combined oven/freeze drying as a cost and energy-efficient drying method for preserving quality attributes and volatile compounds of carrot slices
Get PDFThis article is part of the Research Topic:
Sustainable Approaches to Food Loss and Waste Reduction in Smallholder Horticulture: from Proof of Concept to ScaleIntroduction
An effective and efficient drying method for preserving fresh carrots is essential in food processing. Combined drying represents a novel approach that addresses the shortcomings of conventional methods by balancing energy consumption, cost, and product quality.
Methods
This study evaluated the impact of combining oven drying (OD) with freeze-drying (FD) on drying behavior, energy requirements, costs, enzyme activity, and the physicochemical and sensory properties of dried carrots. Drying conditions included 36 hours of FD, OD, and combinations of OD and FD at 1 h of OD + 21 h of FD (OD1-FD21), 2 h of OD + 18 h of FD (OD2-FD18), 3 h of OD + 15 h of FD (OD3-FD15), and 9 h of OD.
Results and discussion
Compared to FD alone, the OD-FD combination reduced drying time by 39–50% and decreased energy consumption and costs by 40–56%. FD and OD-FD reduced polyphenol oxidase activity by 71–85% and peroxidase activity by 29–52% compared to OD alone. FD carrot slices retained significantly higher levels of β-carotene (11.67–25.96 mg/100 g DM), lycopene (9.91–21.85 mg/100 g DM), total phenolic content (7.12–10.24 mg GAE/100 g DM), and DPPH radical scavenging activity (16.44–19.38 mM AAE/100 g DM) than OD and OD-FD slices. OD-FD slices exhibited the highest levels of volatile compounds, including aldehydes, terpenes, esters, alcohols, ketones, and acids, indicating superior flavor preservation.
Conclusion
The OD2-FD18 combination emerged as the optimal method, significantly reducing energy consumption and costs while maintaining better β-carotene, total phenolic content, DPPH radical scavenging activity, and volatile compound profiles. This study highlights the potential of combined drying methods to enhance drying efficiency and product quality.This work is based on the research supported wholly/in part by the National Research Foundation of South Africa (Grant Number: SPAR231013155231), the Gauteng Department of Agriculture and Rural Development (GDARD) and the University Research Committee at the University of JohannesburgFrontiers in Horticultur