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Electromagnetic and Electronic Aerospace Conformal Load-Bearing Smart Skins: A Review
No full textMultifunctional composite structures (MFCS) have become an increasingly important field of research with the large-scale adoption of composite materials in many industrial sectors such as aerospace, automotive, sport and recreation equipment (bikes, scooters, etc.) and maritime. It is a diverse field which includes scientific areas in electromagnetics, electronics, material sciences, structures and structural augmentation, sensors, and thermal management. The paper investigates Conformal Load-bearing Smart Skins (CLSS) as a part of multifunctional composite structures specifically related to aerospace applications and focuses on the seamless incorporation and synergistic coexistence between electronic devices and composite materials. Current trends in materials and manufacturing processes, as well as measurement techniques used to validate both the electromagnetic and structural responses have been explored and discussed. Furthermore, it identifies some of the challenges and complexities associated with CLSS and explores future areas of research which still need to be addressed
Mechanistic Studies of Antimicrobial Peptide Encapsulation by Lipid Nanocarriers
No full textAntimicrobial resistance (AMR) poses a significant health challenge globally, threatening the effectiveness of antimicrobial agents. A promising class of new antibiotics are antimicrobial peptides (AMPs) which are part of the innate immune system of many organisms including bacteria, fungi, plants, animals and humans. AMPs have gained considerable interest due to their broad-spectrum activity against various pathogens, including those that have developed resistance to conventional antibiotics. While AMPs offer advantages over conventional antibiotics, they also exhibit several disadvantages that limit their clinical use, such as high production costs, potential cytotoxicity, and susceptibility to proteolytic degradation. Recently, research has also focused on ultra-short AMPs which are short derivatives of AMPs, typically ranging from 3 – 10 amino acids in length. Ultra-short AMPs are promising as they have been shown to retain antimicrobial activity but can have easier synthetic pathways and much lower production costs compared to natural AMPs.
Several recent research studies have shown that lipid nanocarriers (NCs) such as cubosomes and hexosomes are highly prospective as drug delivery candidates for antimicrobial agents, such as AMPs. However, the interactions of lipid NCs with bacteria remain poorly understood. To date, the antimicrobial efficacy of AMPs loaded in cubosomes has displayed very high levels of variability and there is no coherent understanding as to why cubosome encapsulation works for some AMPs and not others. A relatively small number of research studies focus on the use of hexosomes as delivery vehicles for AMPs. Additionally, ultra-short AMPs have not been investigated with lipid NCs such as cubosomes and hexosomes as drug delivery systems targeting bacteria. Therefore, research in this thesis initially investigated the interactions of lipid NCs, including cubosomes and hexosomes, with E. coli mimicking supported lipid bilayers (SLBs). The encapsulation of a range of AMPs, including the natural AMP indolicidin and ultra-short peptide fragments derived from indolicidin, in cubosomes was also investigated using both experimental techniques and molecular dynamics simulations. Finally, the effect of a range of parameters including the lipid composition and the lipid NC internal structure on the peptide encapsulation efficiency and the eventual antimicrobial efficacy was assessed against both gram-negative and gram-positive bacterial strains. The results are interpreted with reference to recent models describing the interactions between lipid NCs and bacteria and the known mechanism of action of the peptides.
The interaction of lipid NCs (cubosomes and hexosomes) with E. coli mimicking SLBs was investigated using a combination of experimental techniques including total internal reflection fluorescence microscopy (TIRF-M), quartz crystal microbalance with dissipation (QCM-D), and synchrotron small angle X-ray scattering (SR-SAXS). Incorporation of the fusogenic lipid di-oleoyl phosphatidylethanolamine (DOPE) to the lipid NCs increased the interactions with the bacterial SLB, whereas the addition of a cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) significantly augmented these interactions. The lipid mesophase of cubosomes was disrupted upon interacting with the E. coli model membranes, while hexosomes remained structurally interact. These findings indicate that cubosomes primarily interact with bacterial model membranes through fusion, while hexosomes presumably interact via a different mechanism which preserves their structural integrity, potentially similar to the ‘phase through’ or ‘hemi-fusion’ mechanism observed in eukaryotic membranes.
Encapsulation of the ultra-short AMPs, RW5 and Fmoc-RW5, in cubosomes and the impact on the cubosome mesostructure were investigated using a combination of liquid chromatography-mass spectrometry (LC-MS), SR-SAXS, cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS) and molecular dynamics (MD) simulations. Incorporation of RW5 in both MO and PT cubosomes resulted in very poor encapsulation efficiency. The addition of a hydrophobic Fmoc moiety to this peptide significantly augmented the encapsulation efficiency. This effect was further enhanced in the presence of 150 mM NaCl, which screens repulsion between the cationic peptides. MD simulations confirmed the higher encapsulation efficiency observed for Fmoc-RW5, due to stronger and deeper interactions with the MO bilayer primarily facilitated by the Fmoc group. This study suggests that the addition of a Fmoc group to an AMP is a successful strategy to improve the encapsulation efficiency.
Incorporation and delivery of the AMP indolicidin and its ultra-short derivative priscilicidin in cubosomes were investigated using LC-MS, SR-SAXS, cryo-TEM and DLS. Priscilicidin demonstrated higher encapsulation efficiency in MO cubosomes than indolicidin, presumably due to the fmoc group. Encapsulation of either peptide significantly disrupted the cubic nanostructure in water and effected a conformational change in the peptide. The presence of salt improved the encapsulation efficiency and promoted retention of the cubic mesophase. For both indolicidin and priscilicidin, encapsulation in MO cubosomes generally reduced the antimicrobial activity against gram-negative and gram-positive bacteria. This may be explained by the mechanism of action of these peptides, involving some level of self-assembly which is presumably hindered by encapsulation. These findings are consistent with a recent diffusion to capture model, suggesting that antimicrobial compounds of high permeation, such as AMPs, may not be suitable for cubosome encapsulation.
The addition of the fusogenic lipid DOPE on lipid NC-mediated delivery of both indolicidin and priscilicidin was investigated. The addition of DOPE to MO cubosomes resulted in a phase transition to hexosomes, allowing for a direct comparison between cubosomes and hexosomes for peptide delivery to bacteria. The peptide loading of both indolicidin and priscilicidin increased with the addition of DOPE; a conformational change in both peptides was observed following encapsulation. In the presence of salt, which significantly increased peptide loading, the addition of peptide effected a phase transition towards lipid mesophases of less negative interfacial curvature. These changes are correlated with hydrophobic mismatch between the peptides and the MO bilayer and the depth of AMP insertion into the lipid bilayer. While the addition of DOPE to MO cubosomes was shown to both increase peptide loading and increased interactions with bacterial model membranes, the antimicrobial efficacy of cubosome-loaded peptides was still not higher than that of the free peptide. However, addition of 30 mol% DOPE (and the formation of hexosomes) led to significantly higher antimicrobial activity than MO cubosomes suggesting that the use of DOPE may be an effective strategy, particularly for antimicrobial compounds of low permeation. Findings presented herein emphasise the importance of carefully selecting appropriate AMPs for cubosome encapsulation, as an effective strategy to treat bacterial infections.</p
Performance Optimisation of Molecularly Imprinted Polymers Nanoparticles Based Conductometric Biosensors for Cardiac Biomarker Detection
No full textOver the past decades, cardiovascular diseases (CVDs) have become a major threat to human health across the globe increasing the patient mortality rate. Early diagnosis of the CVDs is important to increase the survival rate of the patients, and one of the key methods to achieve this is through the detection of cardiovascular biomarkers. The conventional methods for diagnosing CVDs via detecting cardiovascular biomarkers typically require bulky instruments in centralised laboratories which are expensive and time consuming. Alternatively, there is a growing interest in developing low-cost, hand-held, and robust biosensors for fast detection of cardiovascular biomarkers for optimal management of patients.
The current study involves, fabrication of conductometric sensors with patterned gold electrodes on high resistive silicon (HR-Si) wafers. The immobilisation of artificial recognition element, also known as molecularly imprinted polymer nanoparticles (nanoMIPs) on (3-glycidyloxypropyl)trimethoxy silane (GPS) functionalised conductometric sensors provides reliable and accurate measurements of clinically significant levels of three selected cardiac biomarkers in human saliva using a label-free approach. The selected cardiac biomarkers used in this study include brain natriuretic peptide (BNP), N-terminal pro-brain natriuretic peptide (NT-proBNP), and cardiac troponin I (cTnI). The sensor performance in detecting the targeted cardiac biomarkers in both media of phosphate buffer solution (PBS) and artificial saliva is evaluated by testing them in ×1000 times diluted cardiac specific nanoMIPs in PBS at pH 7.4 with a 10 minutes of sample incubation. GPS silanisation is important for maximum binding of nanoMIPs onto the sensor surface with correct orientation facilitating the maximum binding of target cardiac biomarkers. The electrical resistance changes are measured within 3 minutes, upon interactions of cardiac nanoMIPs on the sensors with incoming cardiac biomarkers to evaluate the sensor performance. Cardiac nanoMIPs immobilised conductometric biosensors resulting in significant resistance changes with high sensitivity and selectivity in detecting the targeted cardiac biomarkers. The results also showed that these biosensors are also reusable for at least two cycles. These novel conductometric biosensors have the potential to reform cardiac diagnostics, enabling point-of-care testing and bringing diagnostics closer to the patients, thereby improving patient care and outcomes.</p
Performing the Material Poetics of Migration: a (re)Imagined threshold ritual of Tamil women
No full textThis creative practice-led research investigates how a culturally inscribed traditional ritual of Kolam performed at the threshold by women from the Tamil diaspora is (re)imagined into a contemporary practice in clay. Such research invites the viewer to enter a place of encounter. Ritual practices are enactments of cultural and gender identity by diaspora. This generates relational connections relevant to lived experience of migrants through material and social dialogical processes of continuity and change. The experiential, sensory encounter of materiality and performative action on ceramic artefacts and clay are realised in (re)imagined artworks at threshold sites. They activate processes of change that prompt an exploration of the states of transformation accompanying threshold crossings of boundaries experienced by migrants.
The ephemeral, traditional Kolam drawing is created at the threshold of homes and in public spaces using rice flour to communicate a message of wellbeing and of what is happening. The drawing merges with the ground as interaction through movement of people, surrounding matter, and weather, transforms the creation. The (re)imagined practice at intersections is analysed through theoretical perspectives of South Asian cultural practices, and within broader contemporary fine art practices that includes New Materialism and Performance. This framework informs how agencies of materiality and traces, gender performativity through ritual, and community participation, are exercised within the practice. In the project, Performing the Material Poetics of Migration: a (re)Imagined threshold ritual of Tamil women, qualitative research was conducted by engaging practitioners of the traditional Kolam within the diaspora in Australia and Singapore through interviews and on-site observations. The aim was to provide deeper understanding of the interrelations that exist between material and gestural, social, spatial, and devotional aspects of practice. The intrinsic characteristics of Kolam and agency of the feminine in performative gesture, informed the development of (re)imagined creative encounters of material artefacts in clay and ceramic, often incorporating textile to form a hybrid material through an innovative approach. Installations in gallery exhibitions capture the embodiment of women from the Tamil diaspora through Sari drape and gestural acts of ritual in hybrid material in ceramic and textile forms. Artworks were also undertaken as durational socially engaged making of clay artefacts and participatory actions generating traces. The research examines how material agency of clay and ceramic can enable new ways to experience liminality, flux, impermanence, and re-assemblage. The creative research outcomes understand these as iterations of boundary-making and boundary-dismantling, which can be further contextualised through the ongoing material and social transformation emerging within the migrant journey. The threshold constructed as material encounter in clay generates new insight on how practices of culture can be (re)imagined to incorporate migrant lived experience.</p
Policy Transfer for Deep Reinforcement Agents Using Game Entity Substitution – Applied to Infinite Mario
No full textDeep Reinforcement Learning (DRL) agents have shown impressive ability in mastering computer games, but notoriously take a long time to learn. As an agent progresses through a game, it will often encounter new states containing previously unencountered game entities, e.g., new enemies. In such situations, DRL agents typically struggle to generalise their prior knowledge to the new entities, owing to differences in state and object representations. In particular, even when new entities behave similarly to previously encountered ones, if they appear to be different then DRL agents can take a long time to adapt. Policy transfer learning offers a promising approach for allowing DRL agents to adapt their knowledge; however, establishing the connection between the newly presented states (the target task) and previously encountered ones (the source task) requires guidance from a domain expert. Guidance in the form of externally constructed mapping of state-action pairings, must be continually maintained in response to new game entity encounters.
This thesis proposes an alternative approach, where policy transfer is accomplished by leveraging an intermediate state transformation, removing the need for manual mapping. Each entity is mapped to a unique entity ID, and when a new game entity is encountered, a “substitution agent” strives to learn a mapping between the new entity ID and a previously encountered one. For example, if the new entity is a type of enemy, the substitution agent will ideally learn to map the new ID to a previously encountered enemy’s ID, rather than, say, the ID of a powerup item. Experimental results show that this approach is effective, allowing for rapid improvement of end-of-episode scores when encountering new entity representations in the game, Infinite Mario</p
Narratives that nudge: Raising theoretical questions about reflective practice
No full textThe narratives of pre-service teachers in this paper tell a story which interrupts the notion that reflective practice necessarily produces a transformative self. Although this argument is not new, the extent to which the utility of reflective practice is taken for granted in the current context of teacher education (beginning and continuing) remains greater than ever. We show how this normative construction of reflective practice and the understandings of self that it produces in the narratives of pre-service teachers are undermined in the context of schooling. We suggest that further research is needed in this area. Through this effort we raise questions about the spaces in which reflective practice is assumed to operate and the ways in which the reflective self it assumes has been disconnected from society and relations of power. We situate ourselves as teachers, teacher educators and researchers who desire theoretically informed positions from which we can begin to critically address, extend or displace our current understandings of these issues. This paper raises questions about reflective practice and its relationship to pedagogy within the current context of schooling.</p
Strength, mineralogical, microstructural and CO2 emission assessment of waste mortars comprising excavated soil, scallop shells and blast furnace slag
No full textThe construction sector is actively seeking alternatives to Portland cements, with a view to decarbonising cementitious construction materials, such as mortars and concretes. Using pozzolanic industrial mineral wastes (e.g. fly ash and slags) as supplementary cementitious materials (SCMs) is an effective strategy. However, further investigation is required to identify more SCMs that have longevity in supply, with a view to benefiting the circular economy. Excavated soil and scallop shell wastes are becoming increasingly abundant due to urbanisation and aquaculture sectoral expansion. Managing these wastes through their valorisation as construction materials is more sustainable and therefore highly desirable over disposing them to landfill. This study investigates the use of excavated soil and scallop shell wastes as raw materials for manufacturing low-carbon cementitious mortars. Mechanochemical and thermal techniques were investigated as alternatives to alkali reagents for activating strength-gaining properties of the soil waste. Mixtures comprising mechanochemical+thermally activated soil waste with 10% blast furnace slag produced the highest strengths (2.43 MPa) after 28-days and generated ∼50% less CO2 emissions compared with CEM-I-treated mixtures. Furthermore, the compressive strengths performance recorded for mechanochemical+thermally activated soil waste with 10% scallop shells (1.07 MPa) were only 8% less compared with strengths for equivalent mixtures containing 10% type 1 Portland cement. Based on results from regression analyses, Si/Al was the most effective elemental ratio for predicting 7- and 28-day compressive strength of mortars based on filter cake that had been mechanochemical and/or thermally treated through linear functions. Exponential functions were more appropriate for predicting strength based on other elemental ratios, which considered one or a combination of Ca, Na, K and Fe
Social and emotional therapy dog-assisted interventions in mainstream school settings: a systematic review
No full textObjective: The purpose of this systematic review is to synthesise the available evidence of the impact of therapy dog-assisted interventions on the social and emotional wellbeing of students in mainstream school settings through the use of the biopsychosocial framework. Method: The PRISMA 2020 guidelines were followed, and the inclusion criteria included primary outcomes related to social and emotional wellbeing, such as social competencies and mental health. The studies included were conducted in mainstream educational settings, incorporated a therapy dog, provided a comparison or control group and were in English. The quality of the evidence was assessed with the Evidence Project Risk of Bias tool. Results: Of 405 studies identified, seven studies with sufficient rigour met the inclusion criteria of evidence to support the use of therapy dog-assisted interventions to improve social and emotional wellbeing within a school setting. Outcomes consisted of psychological, biological, and social variables contributing to overall wellbeing, such as improved self-perceptions, decreased cortisol levels and improvement in social behaviour and empathy. Conclusions: Findings suggest that therapy dog-assisted interventions can have a positive impact on social behaviours and reducing stress in a school setting; however, there is a need for more rigorous and current research investigating therapy dog-assisted social and emotional wellbeing interventions in mainstream educational settings
The relationship between cryptomarket drug purchase, social networks and adverse drug events: A cross-sectional study
No full textIntroduction: Drug use and trading are typically social activities; however, supply through cryptomarkets can occur without any in-person social contact. People who use drugs alone may be at higher risk of experiencing harms, for example, due to lack of others who may call for emergency assistance. Alternatively, cryptomarkets may be a source of harm reduction information and drugs with better-known content and dose, potentially reducing the risk of adverse events. This study examines relationships between cryptomarket use, drug-using social networks and adverse drug events for MDMA, cocaine and LSD. Method: A subsample of 23,053 respondents from over 70 countries was collected in the 2018 Global Drug Survey. People who reported using MDMA, cocaine or LSD were asked about using cryptomarkets to purchase these drugs; any adverse drug events requiring medical treatment (combining seeking treatment and should have sought treatment but did not); and social networks who they had used the specific drug with. All measures referred to the last 12 months, hereon referred to as ‘recent’. Binary logistic regressions examined relationships between cryptomarket use, drug-using social networks, and adverse drug events, controlling for age, gender, and frequency of drug use. Results: Adverse events from any drug type were low (5.2%) and for each drug; MDMA (3.5%); cocaine (3.3%); and LSD (3.5%). After controlling for covariates, recent cryptomarket use was associated with increased likelihood of having no drug-using network for each drug type. People who recently used cryptomarkets were more likely to report adverse cocaine (AOR = 1.70 (1.22-2.37)) and LSD (AOR = 1.58 (1.12-2.09)) events. For those reporting a network size >1, network characteristics did not differ with recent cryptomarket use; however, those reporting recent cryptomarket use were more likely to report adverse LSD events (AOR = 1.86 (0.99-3.51)). Conclusion: People who reported purchasing drugs from cryptomarket
Synthesis, Photophysical Properties and Self-Assembly of a Tetraphenylethylene-Naphthalene Diimide Donor-Acceptor Molecule
No full textThe development of new π-conjugated molecular structures with controlled self-assembly and distinct photophysical properties is crucial for advancing applications in optoelectronics and biomaterials. This study introduces the synthesis and detailed self-assembly analysis of tetraphenylethylene (TPE) functionalized naphthalene diimide (NDI), a novel donor-acceptor molecular structure referred to as TPE-NDI. The investigation specifically focuses on elucidating the self-assembly behavior of TPE-NDI in mixed solvents of varying polarities, namely chloroform: methylcyclohexane (CHCl3: MCH) and chloroform: methanol (CHCl3: MeOH). Employing a several analytical methodologies, including UV-Vis absorption and fluorescence emission spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS), these self-assembled systems have been comprehensively examined. The results reveal that TPE-NDI manifests as distinct particles in CHCl3: MCH (fMCH=90 %), while transitioning to flower-like assemblies in CHCl3: MeOH (fMeOH=90 %). This finding underscores the critical role of solvent polarity in dictating the morphological characteristics of TPE-NDI self-assembled aggregates. Furthermore, the study proposes a molecular packing mechanism, based on SEM data, offering significant insights into the design and development of functional supramolecular systems. Such advancements in understanding the molecular self-assembly new π-conjugated molecular structures are anticipated to pave the way for novel applications in material science and nanotechnology