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A Culturally Humble Approach to Designing a Sports-Based Youth Development Program With African-Australian Community
No full textThis article draws on the concept of cultural humility, to describe and analyze a decolonizing approach to co-designing a primary prevention basketball program for young African-Australian people in Melbourne, Australia. We explore the potential for genuine collaboration and power-sharing with a culturally diverse community through collaboratively developing the co-design process and resultant program design. This article highlights the central role of UBUNTU in the co-design process, prioritizing African ways of knowing, being, and doing within a Westernized social work and design context. Through reporting on the stages of program design, we offer an example of how Indigenous knowledges and philosophies such as UBUNTU might be incorporated into co-design through cultural humility. We suggest this allows for a transformation of design tools and processes in ways that undermine oppressive and marginalizing power imbalances in design and social work.</p
Engineering poly(ethylene glycol) particles for targeted drug delivery
No full textPoly(ethylene glycol) (PEG) is considered to be the “gold standard” among the stealth polymers employed for drug delivery. Using PEG to modify or engineer particles has thus gained increasing interest because of the ability to prolong blood circulation time and reduce nonspecific biodistribution of particles in vivo, owing to the low fouling and stealth properties of PEG. In addition, endowing PEG-based particles with targeting and drug-loading properties is essential to achieve enhanced drug accumulation at target sites in vivo. In this feature article, we focus on recent work on the synthesis of PEG particles, in which PEG is the main component in the particles. We highlight different synthesis methods used to generate PEG particles, the influence of the physiochemical properties of PEG particles on their stealth and targeting properties, and the application of PEG particles in targeted drug delivery.</p
Play about Place: Expanding the impact of Indigenous-led Creative Placemaking after COVID
No full textThis panel explores new approaches to placemaking through the development of urban play projects led by Indigenous practices that connect with and entangle knowledge with place. Cases studies discuss affordable and engaging experiences that activate existing public spaces, a typology and methodology for analysing the impacts of urban play, and a comparative study of urban play in Narrm/Melbourne and Ōtautahi/Christchurch. Impacts of these projects include First Peoples storytelling experiences, city activation post-pandemic, community engagement, and the potential of ‘creative placemaking’ to make cities more inclusive and resilient post-pandemic.</p
Playing to be in Dja Dja Wurrung Country: a learning program creating locative games
No full textThis paper examines the design and delivery of a learning program with First Nations students, their teachers, community, and non-Indigenous educators that created experimental locative games in the Dja Dja Wurrung region of Bendigo in Victoria, Australia. We discuss the programs experiential, place-based and relational ways of learning and how these were enacted through a reflexive approach embedded in local community and cultural engagement and participation. The games are analyzed in relation to how players connected to Country through playing in Country, demonstrating how their situated and embodied interactions invited a multisensorial engagement with place to support social and physical well-being. The program is critically reflected on as a case study for a two-way learning approach supporting young First Nations people’s connection to, and expression of Country through locative games as place-making experiences.</p
An Interlaced Toolpath Method for Void Reduction in Material Extrusion Additive Manufacturing
No full textAdditive Manufacturing (AM) has transformed industries by enabling the layer-by-layer fabrication of complex geometries. Among the various AM techniques, Material Extrusion (MEX), also known as Fused Filament Fabrication (FFF), is widely recognised for its versatility and accessibility. Despite advancements in FDM, existing void reduction strategies face significant limitations. Pre-deposition approaches often require costly hardware modifications, in-situ methods are rarely optimised for complex geometries, and post-processing adds time and expense. These challenges highlight the need for scalable, hardware-independent techniques that reduce inter-track voids during deposition without compromising process efficiency. Furthermore, there is limited research on the application of such methods across diverse material systems, including thermoplastics, composites, and concrete.
This thesis addresses these challenges by developing the "interlaced printing method," an innovative in-situ toolpath strategy that reduces inter-track voids without requiring hardware modifications or significant increases in print time. The method is systematically applied to various material systems, optimising process parameters to balance porosity reduction and dimensional accuracy.
This research aims to reduce inter-track voids in MEX prints without requiring additional hardware modifications or significant increases in print time. Initially, the method was applied to PLA filaments, demonstrating significant reductions in porosity (from 10% to 1.15%) and a 19% improvement in mechanical strength. Subsequent chapters explore the influence of process parameters, such as extrusion rate and temperature, on void formation, revealing how these factors can be optimised to enhance the quality of MEX prints further.
The key contributions of this thesis include demonstrating significant porosity reduction and mechanical property improvements in PLA through the interlaced method, identifying material-specific limitations in PETG-CF and concrete, and providing a framework for optimising additive manufacturing processes.
Key findings reveal that while the method is effective in some materials, its impact varies significantly based on material properties, such as flexibility and thermal behaviour. Mechanical testing, including three-point bending tests and μCT porosity analysis, is used to quantify the improvements achieved with the interlaced method. The results suggest that in rigid thermoplastic materials like PLA, the interlaced method effectively reduces porosity and enhances mechanical properties. For composite materials like PETG-CF, the method reduces porosity without improving mechanical performance.
The thesis concludes with recommendations for future research, including refining the interlaced method to better accommodate composite and other FFF-compatible materials. It also proposes the need to explore advanced process control strategies, such as real-time temperature adjustments and machine learning algorithms, to optimise the interlaced printing method further in both small-scale and large-scale material extrusion-based additive manufacturing systems.</p
Polyphonic Praxis: Architectural Design in Real‐time and Immersive Gaming Environments
No full text‘Polyphonic Praxis’ is research at the nexus of architectural design, pedagogy, gaming environments, virtual speculative worlds, and future practice. Grounded in the critical exploration of real-time and immersive virtual gaming environments, this research advocates for a highly polyphonous and interdisciplinary approach as an exploration of architectural practice operating within contemporary virtual contexts. Central to this research are three fundamentals: Polemics, Immersions, and Ecologies.
Polemics encompasses the articulation of critical narratives and ideas rooted in socio-cultural, environmental, or technological concerns, shaping the foundation for a speculative world-making process for architectural design. Immersions denote the utilisation of gaming technologies to create real-time, dynamic and immersive environments that aim to enhance designing, communication, representation, and collaboration in architectural design practice and pedagogy. Ecologies refer to the creation of diverse and interconnected environments, spanning virtual constructs and diverse mediums, to convey ideas, foster relationships, and extend the impact of architectural discourse.
This research speculates on an architectural practice that extends beyond traditional disciplinary boundaries, embracing the dynamic relationships between contemporary real-time design processes in gaming media and an interdisciplinary approach. It aims to enrich design discourse, with audiences within and beyond the discipline, and praxis of future architecture.</p
3D Printing of Polylactic Acid and Zinc Oxide Nanocomposites for Biomedical Applications
No full textPoly(lactic acid) (PLA) is one of the most widely used biopolymers in biomedical applications, prized for its biodegradable and biocompatible properties. However, its usage in clinical practice is severely limited by its susceptibility to bacterial contamination. One promising solution involves combining PLA with antibacterial nanofillers, resulting in PLA nanocomposites that possess inherent antibacterial functionalities. Zinc oxide (ZnO) nanoparticles stand out due to their affordability and broad antibacterial spectrum, demonstrating effectiveness against hospital-acquired strains like Escherichia coli and Staphylococcus aureus. Yet, traditional manufacturing methods have constrained PLA-ZnO nanocomposites to simple applications, such as sutures, primarily due to challenges in producing complex geometries.
To expand the biomedical applications of these materials, this research integrates additive manufacturing (AM, a.k.a. three-dimensional (3D) printing), specifically the material extrusion (MEX) technique known as fused filament fabrication (FFF or fused deposition modelling, FDM). This method is particularly efficient for creating intricate structures needed for biomedical devices, such as implants and scaffolds. The simplicity and low operational cost of FFF make it an accessible approach for producing PLA-ZnO nanocomposites that are both cost-effective and inherently resistant to bacterial contamination.
Despite the advantages of AM, its adoption presents challenges that may undermine the viability of these nanocomposites in healthcare. A significant issue is the absence of standardised testing protocols for assessing the mechanical performance of additively manufactured polymers. This lack of benchmark makes it difficult to evaluate the mechanical properties of printed nanocomposites against existing materials, hindering their acceptance in the marketplace.
Moreover, the interaction between ZnO and PLA is critical; ZnO can catalyse the degradation of PLA, especially under high temperatures and shear stresses. This degradation, which is exacerbated during the filament extrusion and FFF process (which involves multiple thermal cycles), can deteriorate the mechanical properties of the nanocomposites and alter their antibacterial efficacy and biocompatibility. Additionally, FFF parts are more porous than those made through conventional methods due to their layered construction, leading to a higher specific surface area that may affect the antibacterial response and cytotoxicity of the materials.
Furthermore, existing literature primarily focuses on the antibacterial properties of PLA-ZnO nanocomposites while often neglecting their biocompatibility. Achieving antibacterial efficacy typically requires high filler loadings, which can increase cytotoxicity. The same mechanisms that confer antibacterial activity to ZnO nanoparticles may also contribute to potential cytotoxic effects, complicating the printability of the nanocomposites. Evidently, overcoming these challenges is fundamental to fully realise the potential of these additively manufactured nanocomposites and enable their acceptance for medical applications.
Following on from the preambular chapters presenting a general introduction to the present research (Chapter 1), a thorough analysis of the state of the art (Chapter 2), and a detailed description of the applied methodologies (Chapter 3), Chapters 4-6 dive into the experimental activities conducted to address the challenges described in the paragraphs above.
In Chapter 4, a case study centred on PLA, the benchmark material, aimed to establish a reliable method for measuring the anisotropic mechanical properties of the printed nanocomposites. The tensile properties were assessed using ASTM D638 and ASTM D3039, two widely recognized standards for FFF parts. The chapter addressed challenges with these standards, particularly the incompatibility of the dog-bone specimen geometry in ASTM D638 for FFF parts, and the absence of standardised specimen size and raster orientation in ASTM D3039. It was concluded that rectangular specimen geometries would be more effective than dog-bone shapes for accurately evaluating the tensile behaviour of FFF parts in this research. Overall, the preliminary experiments highlighted the necessity of reporting specific setup and printing parameters to ensure test repeatability, even when adhering to international standards.
In Chapter 5, the feasibility of using FFF for producing PLA-ZnO nanocomposites was explored through three strategies to reduce PLA thermal degradation: master-batching (pre-mixing high ZnO concentrations with PLA), silane treatment of ZnO nanoparticles, and precise adjustment of ZnO loading (1-5 wt.%). The chapter detailed the entire manufacturing process, highlighting that accelerated matrix degradation from ZnO posed a significant challenge. However, employing melt-mixing improved processability, while keeping filler loading below 2 wt.% and treating ZnO with silane proved effective. Notably, FFF printing did not significantly affect thermal stability, with filament extrusion identified as the main challenge. Overall, the research confirmed the viability of using FFF to create complex geometries with stable mechanical properties.
Finally, in Chapter 6, the experimental campaign assessed the safe adoption of the additively manufactured PLA-ZnO nanocomposites in clinical settings. This involved evaluating their degradation rates in various media, along with their antibacterial properties and cytotoxicity. Remarkably, the nanocomposites demonstrated over 99% bacterial reduction, even at filler loadings lower than those typically reported in the literature. Additionally, the nanocomposites with the lowest filler loading exhibited biocompatibility comparable to neat PLA. Thus, the antibacterial functionalities were confirmed to be retained, and potentially enhanced, post-printing, likely due to the porous hierarchical structure of FFF parts, which facilitated water penetration. This directly increased the degradation rates of the matrix, leading to higher concentrations of ZnO and Zn²⁺, both critical for the antibacterial response of the nanocomposites.
The ability to achieve excellent antibacterial functionality at low filler loadings is advantageous for maintaining biocompatibility. Low filler loadings also reduce the extent of ZnO-induced degradation of the PLA matrix. Furthermore, the silane treatment did not adversely affect the nanocomposites' antibacterial or biocompatibility profiles. Collectively, these findings confirm the suitability of PLA-ZnO nanocomposites for producing non-toxic, antibacterial biomedical devices through additive manufacturing.
In conclusion, this research is pivotal for advancing the use of FFF in producing antibacterial and biocompatible PLA-ZnO nanocomposites, facilitating broader biomedical applications. Ultimately, by addressing mechanical, processing, and biological challenges, this work paves the way for the integration of these nanocomposites into clinical settings.</p
Floating Catalyst Chemical Vapor Deposition Derived Carbon Nanotube Sheets: Optimization and Applications
No full textThe physical macroforms of carbon nanotubes (CNTs) have long been considered a crucial link for translating their exceptional nanoscale properties into practical materials. However, productivity and scalability issues arising from the complex synthesis process have posed significant challenges. The aim of this PhD research is to gain a comprehensive understanding of the direct spinning of CNT aerogel via floating catalyst chemical vapor deposition (FCCVD) to produce CNT sheets. To achieve this, studies were conducted using an indigenously developed FCCVD setup, focusing on the role of underlying parameters in synthesizing non-woven CNT sheets. The process was thoroughly optimized to identify parameters that ensure maximum productivity (carbon conversion rate of 7.5 mg/min), homogeneous purity (IG/ID > 7), and extended production time. Observations and qualitative analyses, including various characterizations, helped identify the functional roles of the input parameters.
The synthesized CNT sheet was then explored to advance current efforts in structural materials for aerospace and environmental remediation applications. First, the CNT sheets were applied to oil-water separation to address the issue of oil spills. The dense CNT sheets were transformed into CNT sponges using a simple foaming approach, maintaining the hydrophobic nature of the CNTs. These sponges were then mechanically reinforced through nano welding of the joints with amorphous carbon, significantly enhancing their compressive strength, modulus, and oil sorption properties. The resulting amorphous carbon-coated CNT sponge demonstrated outstanding results in absorbing oils and organic solvents, outperforming several existing CNT-based materials. Moreover, the developed method required significantly less energy input per gram compared to existing sponge materials, making it a sustainable choice for environmental remediation.
Additionally, the study addressed the low fracture toughness of carbon fiber reinforced polymer (CFRP) composites, a well-known limitation in aerospace applications. The current practice of interleaving CNT films in CFRP composites is limited by their thickness, density, and weak interlaminar bonding with the matrix. To overcome this, the study proposed coating CNTs with ethanolamine to enhance the wettability and bonding of the CNT sheet, regardless of their thickness. The resulting ethanolamine-coated CNT (EACNT) modified CFRP composites exhibited a remarkable improvement in Mode I and Mode II fracture toughness values due to increased interaction with the matrix material. The toughening mechanisms and chemical bonding are discussed in detail for a thorough understanding.
Finally, the study concludes by providing a brief outlook on how the current work can be further extended to foster advancements and innovations in the respective fields for better outcomes.</p
First Nations' Health, Mental Health, Social, and Emotional Wellbeing
No full textIn "First Nations' Health, Mental Health, Social, and Emotional Wellbeing," readers are invited to explore contemporary issues surrounding the health, mental health, and social and emotional wellbeing of First Nations peoples. A compilation of the latest in research, scholarship and clinical practices by a wide range of authors (First Nation and Allies) has been curated to support clinicians and students across the health professions to strengthen their knowledge and promote culturally responsive practice.</p
Integrating Learning and Reasoning for Real Time Control
No full textThe grand challenge of artificial intelligence (AI) is to create a machine that has human-level
performance across a range of tasks. The last fifteen years has seen rapid progress in various
AI domains, including image recognition, game-playing, and recently generative text, image,
and video. Underlying all of these advances are deep neural networks, a wildly successful
paradigm of machine learning. Despite these successes, neural network based systems still have
fundamental issues which cause undesirable outcomes. Their immense size and complexity
render their decisions inscrutable to human understanding, and this same high capacity can lead
to overfitting, where impressive performance within the training distribution fails to generalize
to novel situations. Additionally, the amount of time and data used to train these models is
many orders of magnitudes higher than humans need to reach proficiency at the same tasks.
We will need to address these concerns to make AI systems with truly human capabilities.
One possible avenue is to look at human cognition for inspiration. Dual-system theory is
a promising model of human cognition which posits two distinct modes of thought: the fast,
intuitive System 1, and the slow, deliberative System 2. Deep neural networks mimic the
behaviour of System 1 in many ways: they perform better on tasks that are fast paced with
immediate feedback, and they do not readily provide explanations of their choices. System 2
processes on the other hand allow humans to explicitly reason about counterfactual scenarios
to apply knowledge into new contexts. A natural question then arises: how can we imbue
our current AI systems with greater symbolic and causal reasoning capabilities (the domain of
System 2) to increase learning efficiency and enhance generalisation?
In this thesis I propose an approach to integrating symbolic planning models into deep
reinforcement learning agents. Specifically, I address the following three challenges: (1) How can
incomplete domain models be formally characterised in the context of reinforcement learning? (2)
How can an incomplete domain model be leveraged to reduce sample complexity in reinforcement
learning? (3) How can feedback from a planner be integrated to provide more efficient learning?
I propose new architectures and algorithms to address these questions, demonstrating their
benefits empirically against existing approaches in a range of domains. I also perform theoretical
work to characterise the types of problems which are most likely to be amenable to these
techniques.</p