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Assembling a Record of the Australian Internet: Tracing the Emergence and Evolution of a Nation’s Web Archives
No full textHow are a nation’s library collections imagined and enacted in a globally networked and digital information environment? In this thesis, I explore this question by examining the social and material foundations of a nation’s web archives, which bring together preserved snapshots of web pages and other online materials.
Using ethnographic and historical methods, I chart the emergence and evolution of Australia’s web archives. I focus predominantly on the Australian Web Archive, a collection of billions of web pages selected for preservation by Australia’s network of national and state libraries since 1996 and a collection of social media developed by the State Library of New South Wales since 2012. Using participant observation, interviews, and document analysis, I present one of the first comprehensive studies of a nation’s web archives over three decades—from initial conception, shortly after the publication of Australia’s first website in 1992, to 2022, when the number and type of actors involved in producing and circulating information on the web have changed significantly. Using these methods, I argue that national web archiving is not merely a process of preserving web pages but a relational process whereby what constitutes a national collection in the age of the popular internet is defined, debated, and reimagined by a shifting multitude of actors and interests.
Conceptualising Australia’s web archives as an “infrastructure”, my analysis is structured around three themes—categories, rules, and imaginaries—through which I trace the distinctive contours of these collections. Using this thematic approach, I show how traditional categories used to demarcate the limits of collecting both constrain and enable the formation of web archives, trace the emergence of a sociotechnical assemblage of rules that blend state and private regulations, and examine how dominant meanings surrounding library collections are forged as distinctive constellations of actors interact through new collecting processes. Attending to the social and material foundations that undergird contemporary library collections reveals their shifting boundaries and meanings, thereby making a significant contribution to media and information studies on the embedded values, biases, and politics of web archives and how the categories, rules, and technologies that underpin them shape how an increasingly central element of a nation’s documentary heritage is imagined and enacted.</p
Nanozyme-Based Colorimetric Sensors for the Detection of Urinary Biomarkers of Early Onset Diabetes and Renal Deterioration
No full textNanozymes are nanomaterials that possess intrinsic enzyme-mimicking catalytic activity and have the potential to be used in sensing, disease diagnosis, drug delivery, and environmental remediation applications. In sensing applications, nanozymes produce a colorimetric and/or fluorometric output similar to that of enzyme-linked immunosorbent assay (ELISA). This makes them a potential replacement for ELISA in clinical settings, as they can eliminate the use of natural enzymes, which are susceptible to the surrounding molecules and the environment. Nanozymes can potentially provide stability, easy storage, tunability, and catalytic activity across a wide range of conditions. While nanozyme sensors for disease detection use blood as the source of biomarkers, urine, which contains metabolites eliminated by the kidneys, prostate, liver, pancreas, and other organs, is an abundant source of disease biomarkers. Effective monitoring of these urinary biomarkers can potentially identify diseases at an early stage, monitor disease progression, and assess the effectiveness of treatment.
This thesis focuses on the development of nanozyme sensors to detect key biomarkers associated with diabetes and diabetes-induced renal deterioration. Diabetes is a serious and chronic condition with no cure. Although early diagnosis can reduce the risks associated with diabetes-related complications, this disease is undiagnosed in over 45% of the global population. Urine contains biomarkers that are indicative of early-onset diabetes. Therefore, this thesis attempts to develop nanozyme sensors to detect acid phosphatase (Chapter 3), glucose (Chapters 4 and 5), and uric acid (Chapter 5) in a physiologically relevant range with minimal or no sample treatment or sample dilution.
Chapter 3 shows the potential of Platinum (Pt) nanozyme to detect urinary acid phosphatase (ACP) with high sensitivity and a broad dynamic range. The high oxidase-mimicking activity of Pt nanozymes at pH 5 allows the conventional two-step ACP assay (optimal activity of ACP is also at pH 5) to be performed in a single step, reducing the assay time by half. The ability to detect ACP in the physiologically relevant range in undiluted human urine samples demonstrated the potential of the Pt nanozyme sensor in complex biological fluids. To enhance the commercial potential of nanozyme sensors, Chapters 4 and 5 focus on creating nanozymes on cotton fabric as templates, allowing on-demand tunability of the catalytic reaction. Chapter 4 highlights the importance of creating Ag-based bimetallic nanozymes using a combination of electroless deposition and galvanic replacement reactions. The bimetallic Ag-Pt nanozyme showed peroxidase-mimicking catalytic activity by generating hydroxyl and superoxide radicals, which is ‘atypical’ as peroxidase-mimicking nanozymes are known to only produce hydroxyl radicals. The high catalytic activity of the Ag-Pt nanozyme was used to detect millimolar concentrations of glucose in undiluted human urine samples. Chapter 5 shows the potential of a non-noble metal and amorphous FeOOH nanozyme created on cotton fabrics using electroless plating. As a single metal catalyst, this nanozyme also showed atypical peroxidase-mimicking catalytic activity over a wide pH range (pH 5-7), which enabled the detection of two biomarkers, glucose and uric acid, in undiluted human urine.
Overall, this thesis is an attempt to create new nanozyme-based sensors to detect disease-related biomarkers in urine with minimal sample preparation, which makes them viable for the practical deployment of point-of-care diagnostic systems.</p
Development of Soy Protein Meat Analogues Using High Moisture Extrusion Cooking
No full textGlobal food shortage, aggravated by a steadily increasing world population and diminishing cultivable land, as well as evolving consumer preferences favouring vegetarian/vegan diets have prompted an escalating surge in meat-reduced or meat-less products products. To satisfy this demand, the focus of food manufacturers has been redirected from traditional meat production towards the exploration and utilisation of plant-based proteins.
Due to their exceptional nutritional profile and versatile functional properties, soybean proteins in form of isolates (SPI) and concentrates (SPC) have emerged as frontrunning ingredient for meat analogues, surpassing other plant-based protein sources such as pea or lupin. Particularly the soy proteins’ high protein solubility, water holding capacity (WHC), and gelling ability account for superior texturization capabilities, aiding in approximating the fibrous, multilayered characteristics of meat.
However, the proteins’ physio-chemical properties were found to vary depending on cultivation and/or extraction conditions. Whilst this topic is exhaustively investigated, the impact of the samples’ distinct characteristics on their texturization capabilities upon high moisture extrusion cooking (HMEC) has not yet been fully explored.
The first part of this Ph.D. project explored the functional diversity among six commercially available soy protein powders (one SPC and five SPIs) from different manufacturers, countries and/or batches. This served as foundation for the primary aim of the thesis, i.e., the investigation into how the samples’ unique properties translated into their viscosity pattern upon thermo-mechanical treatment, and further, their ability to be texturized. Moreover, from an application point of view, it was analysed whether (and how) distinct post-processing conditions changed the extrudates’ properties (e.g., water retention capacity). Similarly, it was investigated whether these changes were governed by the inherent physio-chemical properties of the protein powders. Building upon that, the project explored the potential of crosslinker genipin (GNP) in improving the samples’ ability to develop a cohesive, yet fibrous product reminiscent of meat.
The first experimental chapter found significant variations in solubility, protein dispersibility index (PDI), WHC, zeta potential (various pH-levels), and particle size distribution. Protein solubility and PDI values exhibited strong correlations, whereas WHC was notably influenced by particle size distribution. Those soy proteins with high solubility (> 57 %, pH 7.0) demonstrated the greatest increase in diameter upon hydration (factor 2.9 – 4.6) and exhibited the highest WHC at pH 7.0 (3.45 – 4.40 g protein/mL water), holding promise in their conversion into meat-like fibres. Dispersibility test is frequently used for screening plant proteins, however it does not provide the functional properties of protein powders when subjected to thermomechanical processing.
Texturization is commonly achieved by means of high moisture extrusion cooking (HMEC), which exposes the material to high pressure, shear, and temperatures exceeding 100°C. In the second experimental chapter, these conditions were approximated by rheometer and Rapid Visco Analyser (RVA), which examined the samples’ visco-elastic behaviour upon heating to 95 °C, holding, and cooling down to 25 °C. Both instruments revealed strong correlation between solubility, PDI, and final viscosity, underscoring the importance of high solubility for effective protein-protein interaction during thermal treatment. Variations in viscosity patterns were observed between RVA and rheometer due to different recordings of protein aggregation. The addition of SPC/fibre increased the final viscosity of soy protein blends, with the least soluble SPI being impacted the most (factor 5.2), and vice versae. Hence, adjusting the percentage of added fibre should consider the inherent quality of protein powders.
Besides pH value and cooking temperature, the post-processing resilience of extrudates also largely hinges on the material’s inherent properties. The third experimental chapter investigated the retainment of texture of two distinct extrudates, with SPI A outperforming SPI B in revealing a meat-like texture due to good functional properties. Whilst the pH value did not impact the samples’ spatial/dimensional (?) extension, it caused varying effects on water absorption and firmness. When heated at pH 7.0, both samples absorbed water (by 3.32 ± 1.84 %, SPI A and 11.56 ± 1.88 %, SPI B), resulting in decreased hardness, which would be perceived less favourable. Similarly, exposure to pH 4.0 and high temperature (95 °C) resulted in reduced hardness for SPI B, however, SPI A experienced water exclusion and network strengthening, making it suitable for low-acidic dishes like Bolognese sauce.
Further elaborating on the divergences in the samples’ quality, the fourth experimental chapter aimed to elucidate how the cross-linking of GNP influenced the proteins’ viscoelastic behaviour, thereby building upon chapter 2. Samples with favourable functional properties either exhibited further increases in viscosity and gel hardness or were not/only slightly impacted. This was possibly owed to disparities in protein folding affecting their accessibility to GNP. Conversely, SPIs with inferior physicochemical properties benefited from the natural crosslinker; so that 0.10 % GNP brought their viscosity and gel texture to the same level as the other SPIs without the chemical. SPC remained unaffected by GNP addition, likely due to the presence of polysaccharides forming a protective barrier.
In terms of extrusion processing, the fifth experimental chapter revealed the impact of 0.10 % GNP to be most pronounced for samples with inherently good protein quality, with their hardness significantly increasing by +164 to +162 %, while solubility declined by -10.3 % to -11.6 %. However, their overly cohesive, resilient structure raised doubts about GNP's efficacy for these extrudates. Conversely, GNP aided the other two SPIs in steadily enhancing their initially low texturization, transforming them from a homogeneous, loosely connected protein mass to a fibrous, multilayered extrudate with minimal impact on hardness, gumminess, and colour. Hence, GNP enhances texturization in low-quality samples, while its effect on powders with inherently good functionalities is neglectable.
This research demonstrated the strong interrelation of the physio-chemical properties solubility, PDI value and WHC, which were found to differ significantly among the five protein samples. Further, superiority in these inherent quality parameters directly translated into promising texturization capabilities as well as high structural integrity upon post-processing steps. These findings provide valuable insights into the choice of ingredients and formulation of extrusion pre-mixes as well as the processing conditions (95 °C, pH 4.0) required to include extrudates into ready-to-eat dishes. The fact that 0.10 % GNP led to significant texture improvement in low-quality samples set the fundament for future investigations into its application as crosslinking agent in food formulations involving high temperature treatment.</p
Meaning Making in Transitionary Times: A Historic-Cultural Analysis of Sustainability's Inclusion in The Luxury Electric Car Market
No full textThis thesis investigates why and how sustainable luxury has become a culturally legitimate form of consumption. Luxury and sustainability hold quite opposing connotations: luxury is linked with social stratification, ostentation, superficiality, and self-indulgence, while sustainability is associated with moderation, ethics, equity, and altruism. Despite these contradicting meanings, the emergence of sustainable luxury has become a well-established and growing market trend where consumers distance themselves from traditional luxury goods and switch to sustainable luxury. To unravel the paradox of the ‘sustainable luxury’ concept, I turn to consumer culture research, which explores how the marketplace shapes the creation and negotiation of the meaning of consumer goods, and pose two research questions: “How has sustainable luxury acquired its culturally legitimate meaning?” and “How do luxury consumers negotiate identity tensions during macro transitions?”
This doctoral study is grounded in a theoretical framework of meaning making that highlights the role of both the macroenvironment and individuals in shaping and reshaping the meaning of consumer goods throughout historically evolving times. The modern ability to redefine the meaning of luxury comes from the changing macroenvironment: digitalisation, the liquefication of consumption, and the shift toward experiential forms instead of material ownership together with other macroenvironmental shifts allow consumers to reconsider how they interpret luxury goods in their daily lives. As the meaning of luxury has remained mostly unchanged since Veblenian times, the recent inclusion of sustainability in the luxury discourse now challenges exclusivity, excessive materiality, and conspicuousness in the meaning of luxury.
In addressing the problem of sustainable luxury's conceptually contradicting meaning, I focused on the context of the automotive sector where luxury electric vehicles (EV) represent a particularly illustrative case of sustainable luxury. The rich cultural history of luxury cars and the evident recent shift to a new sustainable mode of operation make automobiles an instrumental context for the historical-cultural analysis of the evolving meaning of luxury. This doctoral study, based on Williams’ (1961) cultural analysis, was conducted through two research stages: one consisted of a historical content analysis of luxury cars’ public representation and the other involved carrying out and analysing in-depth interviews with owners of luxury electric vehicles.
The findings from the secondary sources answered the first research question. The examination of four luxury periods from 1855 until 2023 demonstrated how the macroenvironmental shifts – expressed amidst the combined forces of politics, economics, technology, and dominant cultural aspirations – changed over time to gradually add layers of sustainable connotations to the meaning of luxury (despite the presence of greater or smaller fluctuations in the manifestations of overconsumption, materiality, and opulence in each period). The meaning of luxury has transitioned to include sustainability because the macroenvironmental shifts that historically accumulated sustainable connotations coincided with modern ‘lean and green’ dominant cultural aspirations to shape an emergent discourse of sustainability.
The interview findings answered the second research question by unveiling six identity negotiation practices luxury consumers in the study adopted based on their position on the value spectrum between fading and emerging dominant cultural aspirations. During macroenvironmental shifts, these consumers negotiated identity tensions by navigating between fading and emerging discourses and their corresponding webs of meanings. The personal value fit and preference of either discourse influenced which of the six identity negotiation practices each consumer chose to pursue: merging, compartmentalising, justifying, luring, normalising, or pioneering.
Overall, this study’s addition of fading and emergent discourses to the concept of coexisting competing discourses in meaning making is important, because it provides a more in-depth explanation for the conceptual reconfiguration of the social world during the significant cultural changes that occur with digitalisation, liquid consumption, experiential shifts, and other transformations of modern reality. The findings from this research provide a more comprehensive understanding of how consumers navigate their identity shift during macroenvironmental shifts, particularly how they manage tensions arising from competing fading and emerging discourses. The framework of circularity in meaning making during macroenvironmental shifts also helps explain how values that were dominant in society become no longer appealing and how the macroenvironment and individuals respond to the tension between fading and emerging discourses by adapting their attitudes and behaviour and reconstructing the evolving meaning of the symbolic consumer good.
This thesis offers four theoretical contributions: 1) a historical-cultural explanation for the compatibility of luxury and sustainability; 2) the dynamics of the luxury consumer identity; 3) the explanation of the transition of luxury’s meaning towards democratisation, dematerialisation and inconspicuousness, and 4) the symbolic meaning of sustainable consumer good.
From a managerial perspective, this research offers three practical implications: 1) strategic recommendations for addressing sustainable consumers for the luxury marketers, 2) actionable insights for policy makers on how to use current cultural discourse to promote sustainable adoption further, and 3) specific advice to electric car producers on overcoming consumer barriers in switching to EVs.</p
Investigations into Hydrothermal Processing of a Wet Lignocellulosic Paunch Waste
No full textWith increasing population and related increase in the consumption of beef, the sustainable management of waste generated from the cattle paunch generally refereed as a paunch waste is becoming increasingly challenging. For example, Australia alone produces more than 2 million tonnes of beef, generating 500 million tonnes of wet paunch waste in the local abattoirs annually. Globally, annual paunch waste generation is roughly 18 billion tonnes. Paunch waste carries pathogens such as Escherichia coli, Salmonella spp. and has a high biochemical oxygen demand. Therefore, if not managed efficiently it can cause serious environment and health issues. Paunch waste management options in Australia include composting and landfilling, currently costing $60 per tonne. This work has investigated an upcycling approach where paunch waste is converted into high-value products such as crude-oil and hydrochar using a hydrothermal process. The selection of hydrothermal process is made due to the wet nature of paunch waste which originally contains ~95-97 wt.% water. There exists a very limited literature on the hydrothermal processing of paunch waste. Therefore, a state of the art review was initially conducted on the hydrothermal treatment of known similar wet wastes streams namely sewage sludge, food waste and algal sludge to identify gaps in knowledge and to perform benchmarking of paunch waste with other similar waste. Followed by this, a predictive model was developed for hydrothermal processing of paunch waste where temperature, holding time and solid content were identified as the most critical process parameters. Hydrothermal carbonisation (HTC) experiments were then carried out in a 600 mL Parr reactor under an inert N2 atmosphere, and liquefaction rate of up to 80 % at mild conditions (240 °C) was attained with 35-45 wt.% mixed bio-oil (light and heavy) and 20-30 wt.% hydrochar. Based on the experimental and characterisation data, a unique reaction network was developed and rate constants were predicted using a lumped kinetic model. Analysis of modelling data showed a low activation energy of 13.2 kJ/mol for the conversion of paunch waste to aqueous phase, explaining the high conversion rate obtained. The experimental data were also used in conducting a preliminary techno-economic assessment of HTC process. The techno-economic assessment component includes process modelling in ASPEN plus V10 and the discounted cash flow analysis using the Nth-Plant financial assumptions. It was identified that higher initial solids content (i.e. 15 wt.%) returned a higher net present value (NPV) and a shorter payback period. The higher initial capital investment and uncertain sale price for hydrochar and crude-oil were identified as the bottlenecks of HTC. The techno-economic analysis concluded with a finding that standalone conventional HTC of paunch waste may not be commercially attractive. Therefore, two new approaches were further studied, 1. Co-HTC and staged-HTC of paunch waste and 2. Production of high-value magnetic hydrochar. Co-HTC and staged-HTC of paunch waste with locally available biosolids produced from wastewater treatment was studied with an aim to enhance the conversion rate of biosolids and demonstrate the production of high-quality biosolids derived hydrochar with a low heavy metal content through synergistic effect between these feedstock. Also, application of such biosolids derived hydrochar for dye removal from wastewater has been demonstrated. In a second approach, an attempt was made to make an energy neutral HTC process by its potential integration with anaerobic digestion for the production of biogas instead of crude-oil and uplifting the quality of hydrochar by converting them into magnetic hydrochar. This approach is expected to eliminate uncertainty around crude-oil quality, sale price and market and increase the sale price of hydrochar. It was demonstrated that such integration can be either net energy generator or neutral with an increase in the hydrochar quality. It was postulated that if iron could be sourced from dissolved air flotation (DAF) cake or ferric sludge, an attractive NPV can be obtained.</p
Investigation of Biointerfaces of Opportunistic Pathogenic Candida albicans and Environmental Filamentous Aspergillus brasiliensis With Biomimetic Bactericidal Surfaces
No full textIn nature, the distinctive characteristics of the topography of the wings of flying insects have evolved to sustain their lifestyle and environmental conditions. The unique surface topographies of insect wings have inspired many fundamental investigations in areas such as aerodynamics, hydrodynamics, and self-cleaning materials. It has also been shown that insect wings exhibit antibacterial properties. Numerous biomimetic surfaces have been developed to capitalise on the inherent bactericidal properties of the insect wings; however, the antifungal effects of these surfaces remain unknown. This study aimed to determine whether nanostructured surfaces display antifungal properties, and if so, to understand the mechanism by which these properties occur. In addition, it was intended to explore the biointerface interactions occurring between surface nanotopography and fungi in the context of prevention of fungal biofilm formation.Many fungal species such as yeast-like-fungi Candida albicans and environmental fungi Aspergillus brasiliensis are considerably harmful to vulnerable and immunocompromised individuals, children and seniors. Moreover, these invasive environmental fungi have a negative impact on agriculture and business, costing the United States more than US$21 billion in crop losses each year, and in particular, are considered as parasitic microorganisms, which can devastate infrastructure by causing corrosion or deterioration. Hence, there is an urgent need for research to determine whether nanostructured surface display antifungal properties, and if so, to understand the mechanism by which these properties occur.First, through expanding the development of antifungal surfaces based on surface nanotopography, the impact of the titanium surface topology on the formation of Candida albicans biofilms has been investigated. Titanium is a much-used metal using for designing implantable devices in the medical industry. Titanium that has been modified to possess a micro-structured surface, called ‘black titanium’, has been shown to exhibit bactericidal activities against both Gram-positive and Gram-negative bacteria, however, its antifungal properties are still unknown. The distinctive properties of the surface nanoarchitecture, such as roughness, skewness, and kurtosis appeared to be critical in inhibiting Candida albicans attachment via inhibiting the development of biofilm-related phenotypes of Candida albicans cells. Particularly, skewness and kurtosis are essential measurements of a distribution's shape. Skewness relates to the degree of asymmetry in the distribution, while kurtosis indicates the degree of "peakiness" or "flatness" compared to the normal distribution. The outcomes of this study have paved the way for a further investigation of the mechanical properties of C. albicans when attaching on titanium surfaces. The observed changes in the mechanical characteristics of C. albicans cells imply that the unique surface topographical landscape may have caused physical environmental stress, which has a direct effect on the morphology and rigidity of Candida cells during attachment. In parallel with the assessment of antifungal properties of black titanium, the potential biomedical applications of this nanostructured surface were also investigated. It was found that black titanium supported human adipose-derived stem cells (hASCs) growth and proliferation, while maintaining the stemness and osteogenic potential of the cells. It is demonstrated that these antimicrobial nanostructured titanium surfaces represent a promising support for hASCs.Thus, the outcomes of this project significantly advanced our understanding of the mechanisms governing the interactions between fungi and nanostructured surfaces, to allow preventing the formation of yeast biofilms while supporting the growth and differentiation of stem cells.Furthermore, the self-cleaning and antifungal capabilities of the superhydrophobic surfaces of damselfly Calopteryx haemorrhoidalis wings have been investigated. The correlation between the nanostructured pattern and the air entrapment at the micro- and nanoscale has been elucidated and it was found that fungal spores were unable to traverse the air-liquid interface. In contrast, it was confirmed that bacterial cells could cross the air-water barriers and were ruptured upon attachment to the nanopillar surface. These new findings will aid in the development of biomimetic anti-fouling surfaces that possess both bactericidal and antifungal properties. This work influenced the design of the experimental studies that followed. It has further been shown that biomimetic bactericidal nanostructured surfaces such as black silicon (bSi) can poses the antifungal effect against fungal conidia, or spores. Here, antifungal characteristics of nanostructured surfaces such as bSi have been thoroughly investigated to shed light to cell-surface interactions with nanomaterials. The mechanism of spore adhesion to nanostructured surfaces was elucidated by modulating the wettability of the surface.</p
Validating an Agar System to Mimic Soil for Microbiologically Influenced Corrosion of Pipeline Steel
No full textSemi-solid agar has been developed as a substitute of soil for laboratory corrosion studies, in response to several identified weaknesses of traditional electrolytes for electrochemical analysis. Corrosion of metal in soil has often been studied using soil and simulated soil solution in laboratory. The former presents a large number of variables that cannot be controlled in laboratory to allow for systematic variation of crucial soil parameters. The latter is not an ideal replicate to soil, given the lack of unique characteristics, including microbial attachment to metal surfaces, biofilm formation and physical structure. The use of semi-solid agar as electrolyte has instead been shown to be a promising substitute for soil that links the agar system with clay-based soils.
Prior research focused predominantly on developing an agar system as proof of concept, while this work has developed a more detailed understanding of agar as a substitute of soil through a systematic electrochemical investigation into several key corrosion parameters. Key influences of agar on corrosion measurements were established, notably effects of the agar matrix through adjustment of agar and oxygen concentration on surface corrosion characteristics of carbon steel, influenced by changes to local oxygen environments in agar, using surface polarisation resistance and other electrochemical analysis of the surface. Surface characterisation also showcased the influence of oxygen availability on the surface oxide formation characteristics and visual corrosion characteristics. Diffusion of ions and ferrous corrosion products were also found to be strongly influenced by the agar matrix. The essential mechanisms behind some of the key differences with changing agar concentration and oxygen concentration were identified in this analysis.
In addition, this work has drawn strong correlations between the agar system and soil, highlighting the role of the pore structure in corrosion of testing metal. Direct comparison regarding electrochemical activity, diffusion characteristics, and corrosion mechanisms was performed on pipeline steel in aqueous saline solution, saline agar and saline sand to represent soil, which indicated similarities in oxygen diffusion for agar and sand media. Distinct corrosion characteristics and significantly weakened cathodic activity were identified as different to aqueous saline solution for agar and sand media. Corrosion in saline solution was also accelerated through extensive attack at defect sites by the high chloride ion diffusion rate, but such attack was reduced in agar and sand by the limited chloride ion movement and diminished driving force for anodic corrosion activity. The solid nature of agar outperformed aqueous electrolytes as soil replicate to explore soil-related corrosion responses at laboratory scale.
There was also a detailed study of the MIC mechanisms in a semi-solid agar environment using P. aeruginosa commonly in soil. The BCNR theory that suggests accelerated MIC under carbon starvation did not occur, instead the opposite was more likely PYO-mediated respiration that accelerated MIC with more carbon sources. Reduced bacteria growth under carbon saturated conditions was also determined as the result of bacteria migration to rich nutrient media. Although high variability was observed between bacteria growth and corrosion for each condition, general corrosion inhibition was observed by thicker biofilm growth. However, bacteria growth was shown to accelerate corrosion under saturated nutrient agar conditions as a result of MIC by PYO-mediated respiration dominating the bacteria inhibition influence due to agar and sand structural differences. The outcomes demonstrated the care needed when considering MIC with the addition of nutrients to the agar system when representing corrosion in soil.
In summation, the agar system provides confidence and guidance to conduct simplified laboratory study of metallic corrosion in a simplified environmental replicate to qualitatively and quantitatively predict the corrosion behaviour of metal in real service conditions, such as underground pipelines.</p
The Benefits of Piano Lessons from the Perspectives of Parents, Students and Teachers in Kuala Lumpur, Malaysia
No full textThe title of this research study is: “The benefits of piano lessons from the perspectives of parents, students and teachers in Kuala Lumpur, Malaysia.”
Studio music teaching and learning, or private music teaching (in a home environment) is the normal mode of tuition in Kuala Lumpur. Weekly lesson times range from twenty to sixty minutes or more, depending, generally, on the student’s level.
In investigating what parents, students and teachers considered to be the benefits of learning the piano, important insights that impinge on piano teaching and learning were also identified. The research tools consisted of semi-structured survey questionnaires and semi-structured, one-on-one interviews with parents, piano students, and piano teachers.
From the surveys, some personal and broad understandings of reasons why parents send their children to learn to play the piano are gleaned, along with the level of support they give them with respect to piano practice; whether or not students enjoy piano lessons and what they discover and achieve from them; and piano teachers’ perspectives on the benefits they believe students can gain from taking lessons, as well as pertinent issues relating to lessons.
From subsequent interviews, more detailed viewpoints, beliefs and values from parents, students and teachers surfaced. The general value of piano lessons was recognised by all three cohorts. Whilst many were readily obvious, there were others that became more apparent through probing questioning and reflection.
External music examinations play an important role in the music programs of many teachers in Kuala Lumpur: a majority of piano teachers accept and abide by the music examinations syllabi and use them as guidelines for their teaching. The practical examination entails, in addition to the performance of set pieces from different periods of music history, technique, aural skills, sight-reading, rudiments of music and general knowledge. Students can also sit for a theory of music examination as part of the teaching and learning program; here they study the rudiments of music, leading to more advanced knowledge in music harmony and counterpoint. Collectively, these skills contribute to the performance of the pieces they perform. Ultimately, the challenge for students is to be able to ‘interpret’ the perceived perception of the composer and bring to the performance their own stylistic insights. Assisting them to achieve this is a major task for the teacher.
The study considers the importance and the triangulation of the three groups working together for the benefits of the students. This includes examining how, individually and collectively, parents and teachers support and motivate students as they progress and continue with their lessons and develop musically.
The research project was conducted in Kuala Lumpur, Malaysia. The surveys involved 64 parents, 64 students and 73 teachers. In addition, ten parents, ten students and ten teachers were involved in face-to-face semi-structured interviews. Several of the parents surveyed and interviewed had previously had piano lessons themselves; in general, they stated that their reasons for having their children taught piano included to enjoy music-making, to master a new skill, and to develop certain non-musical skills such as discipline, concentration and motivation, among others. Across all three groups, mention was made of the importance of appreciating music and enjoying making music, and reference was made to the perceived benefits of passing external examinations that were a form of ‘credentialing’. Whilst parents in general were not particularly keen for their children to become professional, performing artists, a few entertained the possibility of their children becoming efficient piano teachers.
The study concludes with recommendations with respect to parents, students and teachers in the context of piano teaching and learning in Kuala Lumpur, Malaysia
Microfabricated Platforms for Mimicking the Biomechanics of the Human Cardiovascular System
No full textThe human cardiovascular system is composed of the heart and a complex network of blood vessels, which facilitates the recirculation of blood throughout our body. Its main tasks include the delivery of oxygen and nutrition to different organs, delivery of carbon dioxide and waste materials from different organs, as well as transport of immune cells, proteins, enzymes, and biomarkers across our body. The malfunction of the heart or blood vessels can lead to several chronic or acute cardiovascular diseases, especially in ageing adults.
Animal models have been widely used to understand the complex nature of cardiovascular diseases with the goal of discovering drugs to disrupt and delay the development of such diseases. However, large animal models are expensive, time-consuming, low-throughput, and ethically controversial, while small animal models do not accurately recapitulate the physiology and pathology of the human cardiovascular system. In both cases, animal models do not enable the researchers to dissociate the effect of multiple, interlaced parameters on the development of cardiovascular diseases. These limitations have led to the continuous development of various in vitro models to explore the human cardiovascular system.
Microfabricated technologies, and in particular microfluidics, enable the creation of more realistic, humanized models of the human cardiovascular system. A key feature of these technologies is their ability to mimic the complex biomechanics of the heart and blood vessels, which is mainly dominated by the shear stress caused by the friction between the blood flow and the vessel walls, and the cyclic stretch of the vessel walls caused by heart pulsation.
However, most existing microfabricated models involve complicated, costly, and time-consuming fabrication procedures, which limits their widespread applications. To address this limitation, I dedicated my PhD research to the development of novel microfabricated platforms to recapitulate the complex biomechanics of the human cardiovascular system, which can be created in a timely and costly manner using well-established microfabrication techniques, while are highly modular and controllable.
Chapter 1 provides a brief introduction to cyclic stretch systems, introduces the research gaps and the research questions. Chapter 2 describes a 3D printed cyclic stretch system and its application for studying the mechanobiology of endothelial cells. Chapter 3 describes a microfluidic structure with a deformable surface to mimic the cyclic stretch of blood vessel walls. Chapter 4 describes a microfluidic structure incorporated with a large cavity to mimic the cyclic stretch of the heart chambers. Chapter 5 summarises the outcomes of the research and provides suggestions for future work.
As my first research contribution, I developed a cam-driven cyclic stretch system to study the mechanobiology of vascular endothelial cells. The system utilized soft, deformable cell culture chambers mounted onto a 3D printed, cam-driven mechanism. The device allowed for exposing endothelial cells to customized cyclic stretch profiles, magnitudes, and frequencies for more than 12 hours. The system accommodated four cell culture chambers, each divided into four segments, enabling 16 experiments to be conducted in parallel.
As my second contribution, I developed a highly deformable microfluidic blood vessel model capable of generating customized shear stress and cyclic stretch loads. The model involved a soft, elastomeric membrane mounted on a microfluidic structure, created using well-established 3D printing and soft lithography methods. The model relied on a syringe pump to drive the flow through the system and an automated valve to control the flow. Injection of liquid through the system while closing the valve led to the inflation of the membrane, whereas withdrawal of liquid from the system while closing the valve led to the deflation of the membrane. This simple mechanism was utilized for the cyclic inflation and deflation of the membrane in a highly controlled manner. A comprehensive set of experiments was conducted to characterize the changes in the volume, pressure, and flow rate of the blood vessel model. Experiments demonstrated the utility of this model to induce shear stress and cyclic stretch loads in a simple yet controlled and repeatable manner.
As my third research contribution, I pioneered a microfluidic heart chamber model. The model took advantage of a semi-spherical balloon-shaped membrane patterned onto a microfluidic channel. The model was created using 3D printing and soft lithography methods. The same principle used for the cyclic deformation of the blood vessel model was harnessed here for the cyclic inflation and deflation of the heart chamber model. Owing to its large volume and small thickness, the chamber experienced a substantially large deformation. The buckling of the heart chamber model at high flow rates led to its asymmetric deflation. The versatility of the system was demonstrated by examining the cyclic deformation of two serially connected heart chamber models as well as by embedding the model in a soft elastomeric matrix to recapitulate the soft cardiac tissue.
Overall, the technologies created during my PhD research facilitate the development of versatile, modular, and highly controllable microfluidic models of the human cardiovascular system in a time- and cost-effective manner. Such technologies will pave the way to better understanding the complex biomechanics of the heart and blood vessels, enabling us to elucidate how biomechanical forces govern the development of cardiovascular diseases in a systematic manner. These technologies also provide a unique platform for examining various drugs as well as strategies to enhance the targeted delivery of drugs to the cardiac and vascular tissues.</p
