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Sustainability-related supply chain risks and supply chain performances: The moderating effects of dynamic supply chain management practices
No full textIn recent years, the supply chain has undergone significant transformations due to various factors such as globalization, the COVID-19 pandemic, advancements in information technology, outsourcing, and offshore production. These changes have made the supply network more complex, particularly with regards to sustainability issues, and have increased the vulnerability of the supply chain to sustainability-related risks. However, despite the growing importance of sustainability-related supply chain risks (SSCRs), there is a lack of understanding and inadequate research on critical aspects in the existing literature on this topic, such as how firms in volatile and demand-driven sectors cope with SSCRs and how these risks affect the firms' operational performance. To address this gap, this study investigates the impact of sustainability-related supply chain risks on suppliers, customers, and the economic performance of businesses in the garment industry in Vietnam. Using a sample of 254 garment companies, this study aims to develop a comprehensive measuring scale for supply chain sustainability risk and evaluates the effectiveness of dynamic supply chain management techniques in mitigating the impact of sustainability-related risks on firm performance characteristics. The findings of this research reveal that there is a risk–return trade-off for economic hazards, while no such trade-off is observed for social and environmental hazards. Furthermore, we find that supplier management and supply chain integration methods can assist in the management of environmental hazards, leading to a positive outcome for both businesses and the environment. The research results provide both theoretical and managerial implications for mitigating the risks associated with sustainability in the supply chain. The results suggest that effective management of sustainability-related risks can result in a win-win scenario for both businesses and the environment
Bifurcation analysis of static stability of a tractor-semitrailer under circular motions
No full textThis paper analyses a general qualitative depiction of changes in the configuration of the non-linear model of a tractor-semitrailer with excessive turnability under stationary circular motions within a broad range of control parameters, such as the longitudinal velocity of motion and angle of rotation of the wheels of the controlled unit. It allows us to foresee the jackknifing effect and to estimate the conditions necessary for safe travel. The proposed analysis combines the transparent geometric approach to analyse the configuration of a tractor-semitrailer, which was developed earlier by J.P. Pauwelussen, and the ability to investigate real bifurcations of the non-linear equation of handling and the non-linear equation of folding angle tractor-semitrailer analytically. Based on this approach, we obtain new analytical dependencies that determine the boundaries of divergent loss of stability of the entire manifold of stationary states of a tractor-semitrailer model and estimates of the maximum values of the angle of folding under different values of the vehicle's longitudinal velocity. This is achieved without the prior determination of the manifold of stationary states itself
TiNbO4-coated industrial submicron Si anode for high-performance Li-ion batteries
No full textSilicon (Si) is a promising anode material for Li-ion batteries but suffers from volume change during (de)lithiation, leading to electrode pulverization and capacity decay. To address this issue, we introduced a zero-strain Li-ion conductor TiNbO4 (TNO) coating on the surface of industrial submicron Si using a simple precipitation method. The density functional theory calculation confirmed TNO as an excellent coating layer to alleviate silicon expansion and benefit to the Li diffusion. The resulting compounds were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope, X-ray photoelectron spectroscopy, half-cell charge–discharge tests, and cyclic voltammetry and showed that amorphous TNO was well distributed on the Si particles and can effectively improve the Si anode's cycle performance. After 120 cycles, the TNO-coated Si anode retained 565 mA h g−1 capacity under 0.1 C, which is better than that of pure Si with less than 100 mA h g−1
Emerging adult gamers and their diet – a socio-ecological approach to improve health behaviour
No full textPurpose – This paper aims to understand the opportunities and challenges to engage emerging adult gamers (aged 18–25) in adopting healthier diet behaviours through online games and related platforms such as esports and streaming. The study uses a socio-ecological approach to understand influences and suggests approaches to changing behaviours.
Design/methodology/approach – Purposive and convenience sampling were used to identify (n 1⁄4 13) online gaming industry professionals and emerging adult (EA) gamers for interview. Qualitative thematic analysis of data using NVivo was undertaken.
Findings – Bi-directional influences were found that are potentially impacting EA diet behaviours. Food industry advertising and sponsorships were identified as dominant influences within the behavioural ecology, using microcelebrities and esports events to target EAs. The study identifies a need for social marketers to engage EA gamers in healthful behaviours through interventions across various levels of the behavioural ecology, including those upstream with industry and potential government regulation, to promote better health and balance food marketing. It also identifies future research avenues for engaging gamers in good health.
Originality/value – To the best of the authors’ knowledge, this is the first study to explore the impact of the gaming behavioural ecology on EA diet behaviour. It identifies new channels that social marketers can use to engage EAs, who are difficult to reach through more traditional marketing channels
Temperature-dependent cutting physics in orthogonal cutting of carbon fibre reinforced thermoplastic (CFRTP) composite
No full textThe global commitment towards reducing carbon emissions drives the implementation of sustainable carbon-fibre-reinforced-thermoplastic composites (CFRTPs). However, the machining of CFRTPs presents challenges due to the material's ductile–brittle composition and sensitivity to machining-induced high temperatures. For the first time, we conducted temperature-controlled orthogonal cutting of CFRTP (using CF/PEKK as a demonstrator) to unveil its temperature-dependent cutting physics. Three representative cutting temperatures, 23 ℃ (ambient temperature),100 ℃ (PEKK's glass transition temperature (Tg)) and 200 ℃ (>Tg) and four typical fibre cutting orientations (0°, 45°, 90°, and 135°) have been investigated. The evolution of chip microstructural morphology and surface/subsurface damage have been analysed by advanced microscopy to reveal temperature-dependent material removal mechanisms. The experimental results were elucidated through a novel microscale finite-element-analysis (FEA) model considering thermal softening of the matrix and interface. Results show the transition of the cutting physics with increasing temperature is associated to the degradation of the thermoplastic matrix stiffness/ultimate strength and interface bonding strength and fracture toughness, especially when >Tg
Interfacing β-casein – Phenolic compound interactions via molecular dynamics simulations with diffusion kinetics in delivery vehicles
No full textThe effect that protein-bioactive interactions may have on diffusion kinetics in foods and nutraceuticals was investigated by examining the diffusion kinetics of phenolic compounds (ferulic acid and epicatechin) of varying size, in the presence and absence of bovine β-casein. In the presence of the protein, the diffusion rate for ferulic acid and epicatechin was shown to decrease from 2.76 × 10−11 and 1.33 × 10−11 to 8.51 × 10−12 and 1.00 × 10−12 m2/s, respectively. The magnitude of the decrease in diffusion rate appears to be governed by interaction strength, with pulling simulations and umbrella sampling determining binding energies of −4.6 and −6.7 kcal mol−1 for protein-ferulic acid and protein-epicatechin interactions. This outcome indicates that dissociation of the bioactive from the delivery matrix may be the rate limiting process for diffusion in low solid systems. This work offers valuable insights for the use of pulling/umbrella simulations in understanding the impact of interactions on diffusion in foods and nutraceuticals
Application of hybrid membrane technology to recover resources from concentrates
No full textThe aim of this PhD study is to evaluate and optimize Membrane Distillation Crystallization (MDC) as a sustainable solution for resource recovery from desalination brine. Seawater desalination is increasingly studied to combat freshwater scarcity. However, disposing of the highly saline brine poses several environmental risks. To mitigate this, alternative approaches aiming to recover valuable resources from desalination brine have been conducted. The resources that can be recovered have been studied in Chapter 2, which are minerals and freshwater. The techniques to recover minerals can be divided into pressure-driven techniques, thermal-driven techniques, electro-driven techniques and other techniques while the water recovery techniques employ mainly membrane/thermal integrated hybrid processes. The valuable mineral products have also been reviewed in terms of recovery methods, performance of processes and product quality. The reviewed products are sodium salts (NaCl, NaOH, Na2SO4), lithium salts (LiCl, Li2CO3), magnesium salts (struvite, Mg(OH)2, MgSO4, MgO), calcium salts (CaSO4, CaCO3) and other minerals (U, Rb, Cs). Based on the cost and revenues of each technique, an economic comparison has been conducted along with the cost analysis of operating desalination plants.
MDC is an emerging hybrid thermal membrane technology that synergizes membrane distillation (MD) and crystallization, which can achieve both freshwater and minerals recovery from high concentrated solutions. Due to the outstanding hydrophobic nature of the membranes, MDC has been widely used in numerous fields such as seawater desalination, valuable minerals recovery, industrial wastewater treatment and pharmaceutical applications, where the separation of dissolved solids is required. Despite the fact that MDC has shown great promise in producing both high-purity crystals and freshwater, most studies on MDC remain limited to laboratory scale, and industrializing MDC processes is currently impractical. Chapter 2 summarizes the current state of MDC research, focusing on the mechanisms of MDC, the controls for MD, and the controls for crystallization. Additionally, this chapter categorizes the obstacles hindering the industrialization of MDC into various aspects, including energy consumption, membrane wetting, flux reduction, crystal yield and purity, and crystallizer design. Furthermore, this chapter also indicates the direction for future development of the industrialization of MDC.
Quantitative findings from this research include the development of a new model in Chapter 3 that predicts membrane surface temperatures, permeate flux, and salinity variations. Using the model, impacts of operating parameters such as bulk temperature, flow rate, different membrane materials and feed salinity on the permeate flux as well as the efficiency of driving force were simulated. The results of the simulations indicate that feed temperature, feed flow rate and membrane pore size have the most significant influence on the permeate flux. However, the feed and permeate flow rates have the highest impacts on the temperature polarisation coefficient (TPC) which has the highest value of 0.68 under certain conditions. Besides, the simulations predicted at the saturation point, the seawater and desalination brine have a water recovery of 86.8% and 72.1%, respectively. Finally, the salinity variations with operating time were also simulated and the new model would be vital for the salinity control in desalination processes such as MDC.
Chapter 4 presents experimental results from using a bench-scale MDC to recover high-purity NaCl crystals. In this chapter, crystal samples produced from a bench-scale MDC system have been analysed for crystal morphology, crystal purity and crystal size distribution (CSD). In addition, orthogonal fractional factorial (OFF) experimental design has been introduced to evaluate the influence of various operating conditions on the crystal size and CSD. Feed temperature (40 to 60 °C), crystallization time (60 to 180 min) and the feed composition have been used as the control factors. The results show that the MD in the MDC system maintains a consistent flux of 1.32 to 4.2 kg/m2·h across various feed compositions; higher feed temperatures led to the formation of larger crystal clusters, while longer crystallization time yielded more cubic-shaped crystals; an overall NaCl purity exceeding 99.08% has been achieved throughout all the experiments; and the increased feed temperature and prolonged crystallization time results in a narrower CSD. The result of OFF experimental design identifies feed temperature as the dominant factor affecting crystal size and CSD. However, the presence of impurities in the feed water could pose challenge to the thermal stability and longevity of the membrane.
In conclusion, this study not only confirms the potential of MDC as a sustainable approach for resource recovery from desalination brine but also highlights the critical operational, design, and economic factors that must be addressed for its industrialization. The implications of this research are profound, offering a path towards more sustainable desalination practices and contributing to the broader goal of water security and environmental protection. The quantitative insights and proposed directions for overcoming technological barriers provide a solid foundation for future advancements in the field of membrane technology
Topographical, mechanical, and structural investigation of virus-like particles and self-assembling protein nanoparticles
No full textVirus-like particles (VLPs) are self-assembling protein nanocages derived from viral proteins. They have attracted intense interest from disciplines ranging from soft-matter engineering, catalysis, biomineralization and templating, to medical imaging, diagnostics, drug delivery, and – most relevant to this thesis – vaccinology. Enveloped viruses are over-represented in viral pathogens adversely effecting human health outcomes, and vaccines for many of these harmful viruses are either absent or in need of improvement. By virtue of their size, structure, repetitive geometries and therefore regular presentation of antigen, and their excellent safety profile, VLPs may provide solutions to the challenges of designing efficacious vaccines against enveloped viruses. Finding alternative adjuvants (compounds or molecules co-administered with vaccine formulations to elicit a heightened immune response) may further boost the applicability of VLP vaccines. Characterization of physical features, cellular interactions, and humoral and cellular immune responses generated by VLP vaccine candidates is vital for their commercialization. A detailed understanding of physical, mechanical, and structural characteristics of self-assembling nanoparticles can aid in the design and modification of novel nanostructures for a variety of applications.
This overall goal of this thesis is to provide detailed morphological and biophysical characterization of VLP vaccine candidates from hepatitis C virus and from dengue virus, and to determine the three-dimensional structure of a self-assembling protein nanoparticle. In Chapter 2, hepatitis C VLPs were produced, and their topological and mechanical attributes were determined using Atomic Force Microscopy (AFM) techniques. Ordered packing of viral protein was observed, as was the structurally dynamic nature of enveloped VLPs. Glycosylation of the particles was investigated with a lectin binding array, and the VLPs were found to display similar glycosylation patterns to native hepatitis C virus. The cell attachment and entry behaviour of these particles was determined using fluorescence-assisted cell sorting techniques. Elasticity of the hepatitis C VLPs was determined for the first time, and values were found to be similar to those reported for liposomes.
In Chapter 3, the hepatitis C VLPs were used in AFM force spectroscopy experiments to functionalize AFM probes and interrogate interactions between VLPs and liver cells grown either in monolayer or in organoid cell cultures. Differences in the cells generated in these different cell culture systems were interrogated by fluorescent labelling of key cell surface proteins (receptors) and cell structures, visualized by confocal laser scanning microscopy. Cells in organoid culture were found to resemble in vivo cell architectures more closely than did cells in monolayer culture. Binding interactions between VLPs and cells were only measurable by AFM in the organoid cell culture systems. This provides further evidence that organoid cell culture systems should be adopted for in vitro experiments, to provide more relevant results.
Chapter 4 details development of a novel self-adjuvanted dengue VLP vaccine, again providing detailed characterization by AFM methodologies. A unique cloning strategy was employed, leading to properly matured and therefore appropriately immunogenic VLPs. Epitope presentation on these VLPs was assessed using binding assays with monoclonal antibodies directed to conformationally dependent epitopes on native dengue virus, and the VLPs were found to faithfully reproduce conformationally dependent dengue epitopes. Immunological responses to these nanoparticles were examined in vitro, and in vivo in a mouse model. VLPs were found to be highly immunogenic alone, with the inclusion of the adjuvant seen to significantly increase both cellular and humoral immune responses.
The three-dimensional structure of a self-assembling protein nanoparticle, hemocyanin from the Australian freshwater crustacean Cherax destructor, was determined by CryoEM in Chapter 5, with supporting AFM studies. Hemocyanins are large respiratory proteins which form multimeric supramolecular complexes in a manner analogous to virus self-assembly. Hemocyanins from various organisms have been investigated for a number of biomedical and biotechnological applications. Hemocyanin from C. destructor was found to form a hexamer of monomer protein subunits, the dimensions of which could be approximated as a short cylinder of 10 nm height and 15 nm diameter. In-depth analysis was conducted of interface interactions between protein subunits, shedding light on the mechanism of self-assembly.
In summary, the findings presented in this thesis provide baseline data and methodologies for measuring physical and mechanical qualities of VLP vaccine formulations to allow assessment of genetic modifications, or storage and delivery conditions, and should advance uptake of these important vaccine platforms. Cell cultures suitable for conducting in vitro investigations of viruses are identified, enabling cost- and time-saving relevant data to be obtained before moving to in vivo models. Amino acid level understanding of interactions involved in self-assembly in nanoparticles will support efforts toward design and modification of novel molecules for various applications
Fit to play: how can online Games Be Used to Influence the Dietary Behaviour of Emerging Adults?
No full textThis PhD, Fit to Play: How Can Online Games Be Used to Influence the Dietary behaviour of Emerging Adults aims to understand whether online games and related activities, such as streaming and esports, can be used to positively influence the health behaviour of emerging adults (EAs).
EAs, defined as adults aged 18 to 25, remain a difficult group to engage in healthful behaviours, including positive dietary and eating behaviours. During emerging adulthood, EAs learn behaviours that they carry through to the remainder of their life. Despite this, extant research shows that EAs reduce their fruit and vegetable intake and eat more energy-dense, nutrient-poor (EDNP) foods than during their adolescence.
EAs are the largest users of online games, esports and game streaming. Online games are also linked with negative nutritional outcomes, including increased food consumption, meal skipping and increased risk of high BMI. Online gaming platforms and communities are also being used by the food industry to target EAs. Despite this, there has been limited research into how online game environments can be used to influence EAs’ dietary behaviours. There is also limited evidence of social marketers, such as those in government or health agencies, using online games to engage EAs in better health. To address these limitations, I sought to better understand the social marketing potential for online games through answering the research question: How can online games be used to influence the dietary behaviour of emerging adults?
I explored the research question through the theoretical framework of the Behavioural Ecological Model (BEM). BEMs posit that an individual’s actions are influenced by several external influences. These influences impact their resulting health behaviour – such as food consumption. Using a social constructivist philosophy and qualitative research approach I sought to understand the behavioural ecology that EAs enter into when they play online games, the influence that this ecology might be having on their dietary behaviour and how social marketers can use this ecology to influence EAs.
I delivered the research in three stages. In Stage 1, I explored extant research into EA dietary behaviour, as well as gaming. An EA Gamer Behavioural Ecological Map was produced, which identified influences to be explored in subsequent stages. In Stage 2, I observed 11 online game streaming communities for the popular battle royale game Fortnite. These observations aimed to understand the extent and origins of conversations about food in these online communities. In the final stage, I interviewed esports industry professionals and EA gamers. These 13 interviews provided further insight into the behavioural ecology that EAs engage with, and the intersection of food within the online game ecology.
Through this PhD, I identified 23 influences that may be impacting the dietary behaviour of EAs through online games. In answer to the research question, content creators, professional esports players, virtual peers and esports organisations were identified as the likely conduits for social marketing. Bi-directional influences were identified within my research, underscoring that in online gaming communities, EAs are not a passive audience. When it comes to dietary behaviour, they are likely to be an influencer, as well as be influenced by others.
EA gamers, however, are part of a behavioural ecology where unhealthy food seems to be the norm. This PhD identified that stereotypical depictions of the ‘unhealthy gamer’ may have become a socio-cultural influence that is being embedded in several interactions within the EA gamer behavioural ecology. This includes the discussion of food in online communities, the sponsorship and advertising of food in gaming spaces, and even the types of food that are made available at gaming events – whether professional or amateur in nature. This PhD identifies the potential need for social marketing to readdress the current food narrative within gaming that is likely impacting EAs.
My findings highlight that while there are some clear opportunities to influence EA dietary behaviour through online games there are power imbalances within the gaming ecosystem that need to be tackled by social marketers. The heavy reliance on sponsorship and the low level of government regulation in parts of the gamer ecology, such as esports, creates an environment that favours sponsorship and advertising from the food industry. In this environment, influencers such as content creators, esports teams and tournaments are likely to accept sponsorships without consideration of the health impacts on others within the behavioural ecology.
This PhD calls on social marketers to use my findings to become familiar with the EA gamer behavioural ecology for their future strategies. This ecology should become a mainstay of strategies that target EAs, much like social media has become a permanent part of the media mix. It further outlines opportunities for social marketers to work with the online games and esports industries to consider policies and practices that protect the health of casual, amateur and professional gamers. As exploratory research, I have also outlined a research pathway to further build collective knowledge relevant to my research question. Further work is needed to understand the impact of influences within the EA gamer behavioural ecology on food consumption habits. Research will also be needed to design interventions that tackle dietary behaviour within the EA gamer ecology and readdress socio-cultural norms.
In answering the research question, this PhD has uncovered an influential behavioural ecology that presents opportunities to impact dietary behaviour as well as other healthful behaviours that will support the long-term health of EAs
Monitoring fire-driven forest dynamics over large areas using passive and active remote sensing
No full textForests are an integral part of the Earth’s biosphere, hosting a large proportion of global biodiversity and serving as a major stabilising factor in climate and weather regulation. To ensure their protection, nature reserves and national parks have been established in many parts of the world. Nevertheless, forests are increasingly under stress from the consequences of climate change and other human-driven pressures. In Australia, as in other regions of the world, wildfires are becoming more frequent and severe. Despite the evolutionary adaptation of Australian native vegetation to wildfires, concerns have been raised regarding the resilience of local forests to the changing fire regimes, and their ability to sustainably recover from fire.
Satellite-based remote sensing has been shown to be a reliable and practicable solution for mapping and monitoring forests over large areas. Passive sensors such as those on the Landsat satellites collect multispectral information with a moderate spatial and temporal resolution, providing global wall-to-wall coverage that reaches back several decades. However, Landsat has
well-documented limits in monitoring vertical forest structure. As an active remote sensing technology, lidar can help to fill this gap. Its signal can penetrate the canopy layer and gather information on the vertical distribution of plant material. Combining the advantages of both sensor types has been shown to enable more accurate mapping of forest structure across large areas. In particular, the advent of spaceborne lidar sensors such as the Global Ecosystem Dynamics Investigation (GEDI) has boosted the use of sensor fusion approaches that leverage passive and active remote sensing data for forest structure monitoring. This thesis evaluates the utility of Landsat time series (LTS) and GEDI for mapping forest spectral and structural characteristics following fire disturbance events.
The first research question examined whether conservation efforts can be associated with forest resilience to fire. Specifically, it explored if forest tenure and protection status are related to
post-fire recovery of forests. LTS satellite data was used to evaluate spectral recovery duration following fire disturbance for 25.4 Mha of forested land in southeast Australia. Results show that protected forests on public tenure spectrally recovered on average 0.4 years faster than those on privately held land. However, other factors such as climatic and topographic variables were found to have a far greater impact on forest recovery.
As spectral recovery does not necessarily equate to structural recovery, subsequent research questions focus on how GEDI data can be used in conjunction with LTS. While GEDI is superior to Landsat in measuring attributes of forest structure, it is constrained by a relatively short scheduled mission duration (2019 to 2023) and its design as a monotemporal sampling tool. This thesis proposes a novel approach to overcome these constraints, based on the use of bi-temporal GEDI data. The method leverages footprint-level lidar observations of forest structure from two points in time, using airborne lidar datasets from the pre-GEDI era to simulate a first set of GEDI observations, complemented by a second set of observations provided by the spaceborne GEDI instrument for the same footprint locations, respectively. Throughout this thesis, this concept is referred to as ‘bi-temporal GEDI’ data.
To validate this approach, the second research question compared real and simulated GEDI observations in undisturbed Australian sclerophyll forests. The results confirm that real and simulated GEDI observations, despite certain differences, are generally compatible for combined use in bi-temporal monitoring approaches. Additionally, recommendations were made for the settings of the GEDI simulator and specifications of ALS data used in the simulation. Furthermore, the research determined the main sources of error, namely steep slopes, dense canopy cover and dead standing trees. Highly irregular horizontal forest structure was found to pose a challenge, an issue related to GEDI’s geolocation uncertainty.
To facilitate the novel integration of bi-temporal GEDI observations into established LTS-based forest monitoring approaches, the third research question explored relationships between the two data sources, focussing on the post-fire vegetation response across a range of structural and spectral metrics. One year after the examined fire event, spectral indices showed a moderate to strong decline to between 46.1 and 77 % of pre-fire levels, while most structural metrics demonstrated an even more substantial decline. An exception was canopy height which only dropped to 82.7 % of pre-fire levels. Increased fire severity led to a more pronounced post-fire decline across several spectral and structural metrics. Similarly, greater forest height was found to be associated with a larger post-fire decline across some spectral and structural metrics. Furthermore, the findings suggest the preferential use of GEDI full power beam observations to increase the utility of derived structural metrics.
Finally, in the fourth research question, the novel concept of integrating bi-temporal GEDI into LTS-driven forest change monitoring was implemented. This study evaluated whether employing bi-temporal GEDI data resulted in improved model performance compared to using monotemporal GEDI. The findings show that leveraging bi-temporal GEDI data reduces the RMSE of canopy height change predictions by 0.94 m in undisturbed forest, and 0.49 m in recently disturbed forest. Similar trends were observed for other structural change metrics. Furthermore, the results demonstrate that in forest types with less dense canopy cover (<80 percent), canopy height change predictions from bi-temporal GEDI-driven models yielded a 1.51 m reduction in RMSE. Overall, the results provide evidence that Landsat-based models that were trained with bi-temporal GEDI data were superior in modelling vertical forest structure change, compared to more traditional approaches that were restricted to the use of monotemporal GEDI.
The approach of fusing bi-temporal GEDI observations with multispectral LTS data as presented in this thesis generated promising results, outperforming other more established methods. It can be applied to enhance the monitoring of forest structure in temperate, subtropical, and tropical forests (i.e., areas covered by GEDI’s orbit between 52° N and S) where patches of historical ALS data are available. Leveraging bi-temporal GEDI data might be beneficial for biodiversity mapping, fire behaviour modelling or carbon budget monitoring, as well as studying the impacts of anthropogenic factors on forests