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Oleaginous yeasts as a sustainable alternative source of lipids: an investigation into microbial isolation from food sources, fermentation kinetics, fatty acid profiles, and potential health benefits of microbial lipids
No full textOleaginous yeasts present a promising sustainable source of lipids, also known as single cell oils (SCOs), offering an alternative to traditional oils with potential applications in food industries. In this study, some oleaginous yeast strains, which were isolated from sugarcane bagasse, salted whole anchovies, and pickled mustard greens, were genetically identified as Kodamaea ohmeri, Rhodotorula mucilaginosa, Candida tropicalis, Pichia kudriavzevii, and Zygosaccharomyces rouxii. To investigate the SCOs productivity of these strains, YPD broth was used and compared with low-nitrogen lipid-stimulating medium (LSM) which was enriched with numerous minerals as growth factors. The findings showed that LSM significantly enhanced the production of biomass and SCOs, exhibiting increases of 20.1–40.1% for biomass and 18.5–111.9% for SCOs. Among these strains, R. mucilaginosa exhibited the most proficient biosynthesis of SCOs, achieving a lipid yield of 7.67 g/L in LSM medium, in contrast to the other strains, which yielded between 1.57 and 2.63 g/L, with K. ohmeri following at 4.44 g/L. Accordingly, R. mucilaginosa biomass showed highest lipid accumulation, with values of 531.97 and 301.73 mg lipid/g of dry cell weight recorded for LSM and YPD, respectively. Regarding fatty acid profiles, linoleic acid (C18:2n6C), oleic acid (C18:1n9C), and palmitic acid (C16:0) were the predominant fatty acids identified in the SCOs of five yeast strains and there was a substantially higher contents of linoleic acid (46.92–49.11%) found in SCOs from R. mucilaginosa. Moreover, low atherogenic index, low thrombogenic index, and high hypo-/hyper-cholesterolemic ratio indicate the health benefits of SCOs from oleaginous yeasts as a sustainable alternative lipid source.</p
Microglial activation states and their implications for Alzheimer's Disease
No full textAlzheimer's Disease (AD) is a chronic neurodegenerative disorder characterized by the accumulation of toxic amyloid-beta (Aβ) plaques and neurofibrillary tangles (NFTs) of tau protein in the brain. Microglia, key immune cells of the central nervous system, play an important role in AD development and progression, primarily through their responses to Aβ and NFTs. Initially, microglia can clear Aβ, but in AD, chronic activation overwhelms protective mechanisms, leading to sustained neuroinflammation that enhances plaque toxicity, setting off a damaging cycle that affects neurons, astrocytes, cerebral vasculature, and other microglia. Current AD treatments have been largely ineffective, though emerging immunotherapies focusing on plaque removal show promise, but often overlook the role of neuroinflammation. Activated microglia display a complex range of phenotypes that can be broadly broken into pro- or anti-inflammatory states, although this dichotomy does not describe the significant overlap between states. Aβ can strongly induce inflammatory activity, triggering the production of reactive oxygen species, inflammatory cytokines (e.g., TNF-α, IL-1β, IL-6), synapse engulfment, blood-brain barrier compromise, and impaired Aβ clearance. These processes contribute to neural tissue loss, manifesting as cognitive decline such as impaired executive function and memory. Conversely, anti-inflammatory activation exerts neuroprotective effects by suppressing inflammatory pathways and releasing neurotrophic factors that aid neuron repair and protection. Induction of anti-inflammatory states may offer a dual therapeutic approach to address both neuroinflammation and plaque accumulation in AD. This approach suggests potential strategies to modulate microglial phenotypes, aiming to restore neuroprotective functions and mitigate disease progression by simultaneously targeting inflammation and plaque pathology.</p
Global spread of clade Ib mpox: a growing concern
No full textThe global spread of clade Ib mpox, as evidenced by travel-associated cases in Europe, the Americas, South Asia, and the Middle East, highlights its rapid international dissemination. Since November 2024, the USA has reported four distinct cases, all linked to travel from outbreak regions. Canada confirmed its first case on Nov 22, 2024, associated with travel from Central Africa. By March 2025, multiple cases were reported in Europe, including Sweden (one case), Belgium (five cases), Germany (eight cases), France (two cases), and the UK and Northern Ireland (ten cases).</p
Enhancing 2D hydrodynamic flood model predictions in data-scarce regions through integration of multiple terrain datasets
No full textTopography highly influences hydraulic model predictions. High-resolution Digital Elevation Models (DEM) are currently used in 2D flood modeling studies to create relatively more accurate flood inundation maps. However, the availability of high-resolution datasets, such as Light Detection And Ranging (LiDAR), remains limited due to cost constraints. Thus, low-resolution global datasets are utilized in data-scarce regions. Merging high and low-resolution terrain datasets will be an alternative approach to improve flood models, and comprehensive analysis of such merged DEMs is lacking. Thus, a new DEM (V-DEM) is developed in this study by incorporating available LiDAR, SRTM, local DEM, and river cross-sectional data. 2D unsteady hydrodynamic model predictions are analyzed using the V-DEM, existing low-resolution global datasets, SRTM and MERIT Hydro, and their modified versions. V-DEM was found to create flood flow predictions with a better Nash–Sutcliffe efficiency, significantly outperforming low-resolution global datasets. In addition, MERIT Hydro showed more than 50% improvement in the Nash–Sutcliffe efficiency over SRTM in flow discharge predictions. There is a 110% improvement in the Nash–Sutcliffe efficiency for hydrologically corrected SRTMs over the original SRTM. When SRTM is merged with LiDAR and hydrologically corrected, the predictions also showed an improvement of 146% over the original SRTM. Moreover, this study highlights that the vertical accuracy of terrain datasets has a more significant effect on the flood model predictions than the horizontal resolution, especially in the high and low-gradient regions of the study area. Overall, this study would benefit flood modelers in developing accurate DEMs, especially in the unavailability of high-resolution data for the entire study area.</p
Multicomponent oleogels of ethylcellulose-binary waxes: atomic force microscopy observation and synergistic effect analysis
No full textThe interactions between ethylcellulose (EC) and waxes in multicomponent oleogel systems are underexplored. This study investigated the structural, functional, and physiochemical properties of rice bran oil (RBO) oleogels structured with various ratios of EC and a binary wax blend (9:1 beeswax (BW): carnauba wax (CRW)), varied in 0.5 % w/w increments at a constant total gelator concentration of 4 % w/w. All multicomponent systems formed self-sustaining oleogels at the low gelator concentration. High-resolution atomic force microscopy (AFM) revealed continuous mesh-like EC chains and their presence on the surface of wax crystals in multicomponent oleogels, suggesting co-existing structures. The oil binding capacity (OBC) of EC oleogel increased significantly from 70.92 % to 99.94 % when the binary wax ratio reached 3.5 % w/w. However, the 0.5EC3.5Wax oleogel exhibited a firmer but brittle gel (G' = 87,440 Pa, yield flow points = 0.12 and 0.39 %, respectively), whereas the 3.5EC0.5Wax oleogel significantly improved the yield and flow points (1.82 and 23.35 %, respectively) but reduced G' (4404 Pa). Temperature ramp tests revealed that higher EC ratios led to early viscoelastic structuring, followed by wax crystallisation that reinforces the final network. The highest gelation onset temperature was observed for 4EC at 94.29 °C, which decreased to 89.54 °C in 3.5EC0.5Wax, with the lowest value of 36 °C identified in the 0.5EC3.5Wax oleogel. Fourier-transform infrared (FTIR) spectroscopy confirmed that the multicomponent oleogels were physically stabilized by hydrogen bonding and van der Waals forces. X-ray diffraction (XRD) showed the presence of β' crystals; the crystallinity and plasticity increased with the binary wax ratio. These results show the potential of preparing stable solid fat substitutes using mixtures of EC and binary wax.</p
Digital Platform Durability: Examining the Impact of Structural Attributes
No full textThe digital platform industry has emerged as a significant high-tech sector, experiencing substantial growth over the past few decades. With a market value in the millions of indirect employment opportunities, its impact is undeniable. The rapid digitalisation accelerated by the COVID-19 pandemic is evident across various sectors, serving as a technical response to evolving marketing and commercial communication dynamics. In this fast-paced environment, the adage ”innovate or die” holds true for platforms, highlighting the critical role of innovation in ensuring success amidst rapid ecosystem changes. Platform evolution serves as a key indicator of platform innovation, with platform durability emerging as a crucial evaluation metric. Despite its importance, reviewing the extant literature reveals a gap in understanding how to assess platform durability, particularly concerning the network dynamics and structural attributes of digital platforms throughout their lifespan. This underscores the pressing need for a robust methodology to gauge platform durability and comprehend the impact of structural attributes on digital platform durability (DPD). This PhD study introduces a novel approach to measuring DPD and its associated structural attributes. It addresses the shortcomings of traditional methods for measuring DPD and introduces a new method that leverages the concept of network analysis metrics. Additionally, focusing on a case study within the video game industry, this research analyses panel data spanning from 2001 to 2017 on sixth and seventh-generation video game consoles. Panel data analysis is used to examine the effects of platform structural attributes on digital platform durability.</p
Essays on Religiosity and Finance: Evidence from Saudi Arabia
No full textThis thesis examines the relatively underexplored influences of informal institutions, particularly religiosity, on corporate outcomes. Drawing on the theory of social norms, it investigates how Islamic religiosity, as a form of religious social norms, shapes firm behaviour in Saudi Arabia. The study focuses on three key areas: corporate investment efficiency, corporate risk-taking behaviour and corporate environmental, social, and governance (ESG) practices. The research employs panel data analysis to evaluate these relationships among companies listed in Saudi Arabia from 2012 to 2020.
In the first essay, the primary finding is that the firm’s headquarters, located in a community with a higher Islamic religiosity level, positively influences corporate investment efficiency. Furthermore, our findings indicate that the beneficial link between religiosity and investment efficiency is more pronounced in firms that are not financially constrained and those without significant institutional ownership. In companies that do not face significant financial limitations, the principles guided by Islamic religiosity appear to facilitate more effective investment decisions and better allocations. Similarly, the absence of significant institutional ownership suggests that without strong external governance mechanisms, internal cultural norms such as religiosity can be critical in enhancing monitoring functions, guiding corporate behaviour, and improving investment efficiency. Finally, our study finds a negative correlation between Islamic religiosity and agency costs. This finding implies that the advantageous effect of Islamic religiosity may largely stem from its role in diminishing agency conflicts. Reducing these conflicts plays a key role in the beneficial outcomes associated with implementing these norms.
In the second essay, empirical evidence demonstrates that firms headquartered in communities with higher Islamic religiosity tend to engage in lower levels of corporate risk-taking. This effect is more pronounced in firms with lower institutional and foreign ownership, where external monitoring is weaker. The results suggest that Islamic religiosity plays a monitoring role, helping to curb excessive risk-taking. They support the proposed mechanism that religiosity constrains corporate risk-taking, especially in settings with limited institutional oversight. Moreover, the influence of Islamic religiosity appears to be offset in firms with foreign ownership, likely due to the introduction of different cultural norms and governance practices. Conversely, firms without foreign ownership appear more aligned with local religious norms, reinforcing the inverse relationship between religiosity and risk-taking.
Furthermore, the study identifies a positive relationship between Islamic religiosity and corporate performance. Firms headquartered in communities with higher levels of religiosity are more likely to experience exceptional positive performance and are less susceptible to extreme negative outcomes. This balance contributes to their superior average performance and highlights the value-enhancing effects of religiosity. Path analysis further shows that Islamic religiosity reduces risk-taking, which, in turn, contributes to higher firm performance.
In the third essay, findings reveal that firms operating in communities with higher levels of Islamic religiosity tend to exhibit lower ESG activities. This effect is particularly pronounced among financially constrained firms, where the added costs and potential inefficiencies of ESG initiatives may shrink profit margins and thus weaken managerial incentives to invest in them, especially when firms align with prevailing religious norms and enjoy the confidence of market participants. Moreover, higher levels of Islamic religiosity are associated with reduced agency costs, indicating that Islamic religiosity promotes ethical behaviour and limits managerial self-interest, thereby diminishing the need for ESG as a governance mechanism. These findings suggest that Islamic social norms can serve as a substitute for corporate ESG. In highly religious environments, where ethical conduct is expected and stakeholder trust is strong, ESG activities may offer limited signalling value and appear less necessary.
These results provide important implications for policymakers and investors, offering insights into decision-making processes in emerging markets. By addressing the previously unexplored relationship between Islamic religiosity and corporate outcomes, this thesis enriches the existing literature and sheds light on the unique characteristics of the Saudi financial market as an emerging economy.</p
Midlife Men, Consumption and Wellbeing
No full textThis thesis explores how the consumption behaviour of Australian midlife men (MLM), aged between 45 and 65, supports their health and wellbeing (HWB) across physical, mental, financial, and relational domains—key areas reflected in both hedonic and eudaimonic wellbeing models. It moves beyond (but does not exclude) traditional health-related goods and services to consider a broader range of material and experiential consumption that men engage in as they strive for life goals and maintain wellbeing as they transition into later life.Midlife is a liminal and often overlooked life stage, where decisions have long-term implications for ageing well. For MLM, this stage is characterised by intersecting pressures: raising or supporting children, caring for ageing parents, managing finances and careers, and facing their own age-related health concerns. Layered onto this are traditional masculine expectations around self-reliance and emotional restraint. This research explores how these pressures, roles, and norms shape the ways men consume to achieve HWB.The study is informed by Self-Determination Theory (SDT) and Possible Selves Theory (PST). SDT’s domains of autonomy, competence, and relatedness are used to explain how consumption supports eudaimonic and hedonic wellbeing. PST provides a lens to understand how men consume to move toward desired future selves—and away from feared ones. A conceptual framework was developed from these theoretical foundations to explore how wellbeing-related goals are expressed through consumption.Qualitative methods were employed within a critical realist framework. In-depth interviews were conducted with MLM from a range of socioeconomic and cultural backgrounds, living in both metropolitan and regional areas. The data show a clear shift in masculine behaviour, with growing recognition that taking care of one’s physical and mental health—and investing in self—has become more socially acceptable. The influence of peers and role models—described here as peer positive social control (PPSC)—was central to this shift. These PPSC settings helped men enact autonomy (making their own health decisions), develop competence (through skill-based self-care), and build connection (relatedness), aligning with traditional masculine values while enabling more expansive wellbeing goals.Routine, everyday consumption - like walking, going to the gym, or participating in hobbies - was found to contribute not only to physical and mental wellbeing but also to self-direction and self-actualisation. Importantly, men valued shared experiential consumption over material goods, especially where it enhanced social bonds and personal growth. Rather than reflecting identity loss or compensatory consumption, these practices reflected a reworking of masculine norms around care, contribution, and connection.This research contributes to theory and practice by: 1) applying SDT and PST to a consumption context, particularly midlife men’s consumption 2) identifying PPSC as a bridge between masculine norms and HWB behaviours 3) showing how consumption supports multiple wellbeing domains 4) adding gendered insight into goal-setting literature, and 5) offering a practical basis for understanding wellbeing-focused consumption. Implications are offered for marketing, social marketing, health promotion, and policy.</p
Technological Interventions for Value Addition of Polyherbal Spent Materials from Ayurvedic Industries
No full textThis thesis investigates the valorisation of Dashamoola spent material (DSM), a significant waste stream in the Ayurvedic industry. DSM is produced in substantial quantities as a by product of manufacturing Dashamoola concoction, a traditional mixture derived from ten medicinal plants. Building on the premise that DSM contains valuable lignocellulosic biomass (e.g. cellulose and lignin) and health-promoting phenolic compounds, this research explores their extraction, modification, and application in value-added products. Currently discarded as waste, DSM is proposed as a promising source of phenolic compounds, cellulose, and lignin, which could be modified, characterised, and utilised in emulsions, nutrient-rich food formulations, and active packaging. The introduction chapter establishes the context by highlighting the growing manufacture of Ayurvedic formulations, driven by increasing demand, which has led to a concurrent rise in associated waste streams, including DSM. The lack of effective valorisation of these waste streams is exacerbating environmental challenges and resulting in the underutilisation of a valuable resource. Despite their potential, the Ayurvedic industry has yet to systematically valorise its waste streams to address this issue. This chapter underscores the significance of valorising Ayurvedic waste streams, using DSM as an example to extract, modify, and apply phenolic compounds, cellulose, and lignin as valuable ingredients. This approach aligns with circular economy principles and provides a pathway to address the sustainability concerns of the Ayurvedic industry. The first experimental chapter focuses on the extraction of phenolic compounds from DSM through an optimised pathway, followed by the identification and characterisation of key compounds. The analyses identified several valuable phenolic compounds in Dashamoola spent material extracts (DSME), including shikimic acid (83.2 mg/g), gallic acid (51.2 mg/g), epicatechin (26.3 mg/g), naringenin (25.0 mg/g), and vanillic acid (14.1 mg/g). The results demonstrated that the DSME possessed significant antioxidant, antidiabetic, and anti 1 inflammatory properties, as evidenced by DPPH data. DSME also showed showed significant anti-inflammatory capability closely matching with that of aspirin. DSME did not show adverse health effects as cell tolerability was up to 500 μg/mL in L6 myoblast and RAW 264.7 cells. These findings highlight DSME’s potential as a promising candidate for incorporation into health-promoting foods and nutraceuticals. These results establish DSM as a valuable source of high-value phenolic compounds. The second experimental chapter focuses on the extraction and characterisation of lignin from DSM and its conversion into lignin nanoparticles (LNPs). The LNPs were effective, as natural stabilisers, to stabilise Pickering emulsions for 90 days. These emulsions were able to load 87.9% curcumin and 72.6% of Vitamin D3. Cell line studies confirmed the non-toxic nature of the emulsions, with LnE+Cu+vD3 causing only 29.3% and 34.9% cell death in L6 and RAW 264.7 cells, respectively, at the highest concentration (50 µg/mL). These findings establish that lignin nanoparticles derived from DSM can serve as effective Pickering emulsifiers and encapsulating materials for high-value unstable compounds. The third experimental chapter explores the application of LNP-stabilised Pickering emulsions in creating nutrient-fortified extruded snacks. LNP-stabilised emulsions containing curcumin and vitamin D3 were incorporated into the blended flour feed and then extruded. The resulting fortified snacks retained curcumin and vitamin D3 bioavailability and improved their thermal stability by 69.0% and 65.7%, respectively. Thse findings highlight the potential of LNP stabilised emulsions to protect functional compounds and create nutrient-rich snack foods, helping to address micronutrient deficiencies while contributing to the valorisation of Ayurvedic spent materials. The fourth experimental chapter focuses on the development of active and biodegradable packaging films using lignin and cellulose nanoparticles (LNPs and NCPs) derived from DSM. The films were produced using polyvinyl alcohol (PVOH) as the matrix, incorporating NCPs and LNPs and tea tree oil (TTO, 16% w/v) as functional additives. The resulting films exhibited 2 antimicrobial, antioxidant (85% DPPH scavenging), and UV-blocking (95% transmittance reduction) properties without compromising mechanical strength. Nanocellulose provided structure-reinforcing properties, LNPs contributed antioxidant activity and UV-blocking, and tea tree oil exhibited strong antimicrobial efficacy against E. coli. These films extended the shelf life of strawberries by 14 days under chilling conditions. These findings highlight the potential of LNPs and nanocellulose, derived from DSM, in creating sustainable active packaging solutions, extending the shelf life of perishable foods while valorising Ayurvedic waste streams. As summarised above, DSM is a valuable source of phenolic compounds, cellulose, and lignin, which can be extracted, transformed, and applied in food and other industries. This thesis demonstrates the feasibility and importance of valorising DSM and similar Ayurvedic spent materials by using these components to produce emulsions, encapsulate unstable nutrients, develop nutritionally enriched snacks, and create active, biodegradable packaging. These findings have important implications for valorising waste in the Ayurvedic industry, promoting sustainability and waste reduction. This thesis makes a significant contribution to knowledge by advancing the extraction, transformation, and application of phenolic compounds, cellulose, and lignin from DSM. It also establishes a foundation for exploring the sustainable use of other waste streams of the Ayurvedic sector. The contribution of this work is reflected in four papers (three in Q1 journals) and one manuscript currently under review, underscoring its value to the field.</p
The Mental Health of Australian, Chinese and Vietnamese University Students: A Cross-Cultural Comparison of the DASS-21
No full textThe DASS-21 has been widely used in university student mental health research. However, studies on its cross-cultural reliability and validity, particularly among Eastern student populations, remain limited. This study examined the DASS-21's psychometric properties and measurement invariance across Australian, Chinese and Vietnamese students. Data were drawn from multiple surveys conducted between 2017 and 2021, comprising 2420 university students from Australia (n = 1093), China (n = 626) and Vietnam (n = 701). Single-group confirmatory factor analyses (CFAs) supported the three-factor model of the DASS-21 with acceptable fit for each cultural group, requiring minor modifications for Chinese and Vietnamese data. Multiple-group CFAs resulted in an 18-item version (DASS-18) that achieved cross-group measurement invariance and acceptable internal consistency. Non-parametric tests revealed the lowest scores for all the DASS-18 results among Australian students, while Chinese students reported the highest level of anxiety and Vietnamese students reported the highest level of depression. The two Asian samples exhibited similar levels of stress and overall distress. In general, this study supports the measurement invariance of the DASS, with caution regarding culturally sensitive items. Implications for the DASS-21's universality and recommendations for future research and multicultural psychological assessment are discussed.</p