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  • (2022) Nguyen, Robert
    Thesis
    Data-driven decision making is everywhere in the modern sporting world. The most well-known example of this is the Moneyball movement in Major League Baseball (MLB), which built on research by Sherri Nichols in the 1980s, but sport analytics has also driven major changes in strategy in basketball, the National Football League, and soccer. In Australia, sports analytics has not had quite the same influence in its major domestic codes. In this thesis, we develop tools to assist the analytics community in two major Australian commercial sports. For Australian Rules Football, the largest commercial sport in Australia, data was not readily accessible for the national competition, the Australian Football League (AFL). Data access is fundamental to data analysis, so this has been a major constraint on the capacity of the AFL analytics community to grow. In this thesis, this issued is solved by making AFL data readily accessible through the R package fitzRoy. This package has already proven to be quite successful and has seen uptake from the media, fans, and club analysts. Expected points models are widely used across sports to inform tactical decision making, but as currently implemented, they confound the effects of decisions on points scored and the situations that the decisions tend to be made in. In Chapter 3, a new expected points approach is proposed, which conditions on match situation when estimating the effect of decisions on expected points. Hence we call this a conditional Expected Points (cEP) model. Our cEP model is used to provide new insight into fourth Down (NFL) decision-making in the National Football League, and decision-making when awarded a penalty in Rugby League. The National Rugby League (NRL) is the leading competition of Australia’s second largest commercial sport it is played on a pitch that is 100m long and 70m wide, and the NRL have provided us with detailed event data from the previous five seasons, used in academic research for the first time in this thesis. We found that NRL teams should kick for goal from penalties much more often than is currently the case. In Chapter 4 we develop a live probability model for predicting the winner of a Rugby League game using data that is collected live. This model could be used by the National Rugby League during broadcasts to enhance their coverage by reporting live win probabilities. While most live probability models are constructed using scores only, the availability of live event data meant we could investigate whether models constructed using event data have better predictive performance. We were able to show that in addition to score differential that the addition of covariates such as missed tackles can improve the prediction. Clubs use their own domain knowledge to test their own live win probability theories with the R scripts that are provided to the NRL

  • (2022) Gautam, Shreedhar
    Thesis
    Extracellular vesicles (EVs) are phospholipid membrane bound sacs (vesicles) produced from almost all types of cells. They are found in circulation and contain the cargo biomolecules such as nucleic acids, proteins, lipids, and amino acids. EVs are involved in trafficking these biomolecules between cells and as such have the role in physiological and pathological processes. EVs are heterogenous and revealing their heterogeneity is crucial to understand their explicit physiological and pathological roles. Current isolation techniques cannot sort EVs based on their biogenesis and provides average information instead of each EVs subtype. Thus, single EVs analysis was popular and many surface protein characterization techniques are developed. But there are no techniques available for internal cargo analysis of individual EVs. The overall aim was to develop a technique to analyse internal microRNA cargo content, if possible, for single EVs, if not from the minimum number of EVs. To achieve that goal, light activated electrochemistry, a technique where focused light beam was illuminated on the semiconductor surface and make it electrochemically active was used. The surface was protected against oxidation during electrochemical reactions by grafting self-assembled monolayer of 1,8-nonadiyne. Then, silicon-based surface was patterned with polymers, antibodies, and cells using the light patterns. As a result, the first milestone to prepare light-assisted patterned semiconductor surface was achieved for our overall aim of analysing content of individual EVs. The size range of EVs is 30 to 200 nm, still very low compared to 30 µm which is the best spatial resolution achieved for light activated electrochemistry using crystalline silicon. Thus, chapter 4 developed a technique to improve the spatial resolution of light activated electrochemistry using amorphous silicon. Amorphous silicon has short diffusion length of charge carriers compared to crystalline silicon due to the defect states in band gap called as localized states. So, charge carriers are frequently trapped in these localized states leading to 60 times improvement in spatial resolution to 500 nm. But even this spatial resolution was not enough to analyse individual EVs. So, microRNA content from pool of EVs were detected using the screen-printed electrodes in a high throughput manner instead of single EVs.

  • (2022) Cao, Jun
    Thesis
    This thesis focuses on the development and applications of magnetic resonance electrical properties tomography (MREPT), which is an emerging imaging modality to noninvasively obtain the electrical properties of tissues, such as conductivity and permittivity. Chapter 2 describes the general information about human research ethics, MRI scanner, MR sequence and the method of phase-based MREPT implemented in this thesis. Chapter 3 examines the repeatability of phase-based MREPT in the brain conductivity measurement using balanced fast field echo (bFFE) and turbo spin echo (TSE) sequences, and investigate the effects of compressed SENSE, whole-head B_1 shimming and video watching during scan on the measurement precision. Chapter 4 investigates the conductivity signal in response to short-duration visual stimulus, compares the signal and functional activation pathway with that of BOLD, and tests the consistency of functional conductivity imaging (funCI) with visual stimulation across participants. Chapter 5 extends the use of functional conductivity imaging to somatosensory stimulation and trigeminal nerve stimulation to evaluate the consistency of functional conductivity activation across different types of stimuli. In addition, visual adaptation experiment is performed to test if the repetition suppression effect can be observed using funCI. Chapter 6 explores if resting state conductivity networks can be reliably constructed using resting state funCI, evaluates the consistency of persistent homology architectures, and compares the links between nodes in the whole brain. Chapter 7 investigates the feasibility of prostate conductivity imaging using MREPT, and distinctive features in the conductivity distribution between healthy participants and participants with suspected abnormalities.

  • (2022) Wang, Shuangyue
    Thesis
    Two-dimensional transition metal dichalcogenide (TMD) nanocrystals (NCs) exhibit unique optical and electrocatalytic properties. However, the growth of uniform and high-quality NCs of monolayer TMD remains a challenge. Until now, most of them are synthesized via solution-based hydrothermal process or ultrasonic exfoliation method, in which the capping ligands introduced from organic solution often quench the optical and electrocatalytic properties of TMD NCs. Moreover, it is difficult to homogeneously disperse the solution-based TMD NCs on a substrate for device fabrication since the dispersed NCs can easily aggregate. Here, we put forward a novel CVD method to grow closely-spaced TMD NCs and explored the growth mechanism and attempts on the size control. Their applications acting as electrocatalysts and adhesion layer for Au film deposition have been also well displayed. Through the whole chapters of this thesis, the following aspects are highlighted: 1. MoS2 and other TMD nanocrystals have been grown on the c-plane sapphire. The surface oxygen vacancies determine the density of TMD nanocrystals. The MoS2 nanocrystals demonstrate excellent hydrogen evolution reaction and surface-enhanced Raman scattering performance owing to the abundant edges. 2. Deep insights into the growth of MoS2 nanograins have been explored. The surface step edges and lattice structures of the underlying sapphire substrates have a significant influence on the growth behaviors. The step edges could modulate the aggregation of MoS2 nanograins to form unidirectional triangular islands. The Raman spectra of MoS2 demonstrate a linear relationship with the crystal size of MoS2. 3. The orientation of sapphire substrate has an of importance effect on the critical size of MoS2 nanocrystals. The MoS2 nanocrystals have the smallest size on the r-plane sapphire, besides, the MoS2 on r-plane sapphire demonstrates the sintering-resistance feature, which is attributed to the edge-pinning effect when MoS2 edges are anchored on the sapphire surface. 4. The MoS2 nanocrystalline layer was utilized as the adhesion layer for Au film depositing on a sapphire substrate. The Au films on MoS2 displayed superior transmittance and electrical conductivity as well as outstanding thermal stability, which lay in the strong binding of Au film with MoS2 nanocrystalline layer.

  • (2022) Bartolec-Criss, Tara
    Thesis
    The function of a protein is mediated by its ability to form precise three-dimensional structures or specific protein-protein interaction (PPI) interfaces. However, it has been challenging to study these aspects of the proteome at scale, in sufficient detail, and in a generalisable way. Cross-linking mass spectrometry (XL-MS) performed on high complexity samples (such as entire organelles or cells) theoretically enables the large scale mapping and monitoring of protein structural conformations and PPI interfaces in native proteoforms. However, as the large scale XL-MS field is young and historically driven by the reporting of technological innovations, assessment of the biological accuracy (and overall utility) of large scale XL-MS studies is still largely underexplored. This thesis applies large scale XL-MS to two eukaryotic systems (Saccharomyces cerevisiae and cultured human cells) and is presented as three independent studies. Firstly, it reports the first budding yeast XL-MS interactome, generated by cross-linking intact nuclei isolated from wild-type cells with DSSO. The wealth of yeast interactome data enabled identification of an inflated false discovery rate for cross-links representing PPIs, and development of a novel quality control approach. Surprisingly, the high confidence PPIs were substantially orthogonal to historical binary interactome mapping efforts. Subsequently, it reports the largest XL-MS dataset currently available for any species, generated by diversifying analyses (cross-linkers, mass spectrometry analyses, software) performed on organelles isolated from human HEK293 cells. Here, we show how the ~30,000 low-resolution distance constraints generated in near-native proteoforms can be used to uniquely (1) contextualise regions within existing experimental protein structures, (2) annotate interfaces in PPIs and multi-protein complexes, and (3) validate structures predicted by computational modellers like AlphaFold. Finally, this thesis reports the use of quantitative XL-MS to explore links between gene function and cellular phenotype, comparing wild-type yeast with a highly pleiotropic deletion strain (Δhpm1) using SILAC multiplexing and PIR cross-linking of intact cells. The untargeted comparison of structural conformations and PPIs uniquely enabled insights into phenotypes entirely invisible to investigation of protein abundance alone. This thesis will therefore argue that XL-MS is the missing link in the systems biology toolbox.

  • (2022) Gutierrez Chavez, Carolina
    Thesis
    Microbial motility is a survival strategy. Bacteria utilise motility in growth and reproduction to protect against desiccation and antibiotics, defend against competitors, colonise new habitats, and find nutrient-rich environments. Antarctica is the most extreme and pristine region on Earth. Here, soils are exposed to low temperatures, considerable levels of UV radiation, strong winds, extreme drought, and low availability of nutrients. Currently, there are no reports of motility in polar soil bacteria. Due to the extreme conditions in the Antarctic continent, we used these polar desert soils as a study model. We hypothesise that Antarctic soils are an ideal environment for bacteria to perform motility to find more favourable conditions. In this thesis, we describe for the first-time mechanisms of motility by Antarctic soil bacteria. As model microorganisms, we selected bacteria from the genera Streptomyces and Arthrobacter, belonging to the phylum Actinomycetota, the most abundant in East Antarctic soils. The first aim was to investigate the incidence and behaviour of Antarctic Streptomyces performing exploration. The genus Streptomyces had been described as a group of sessile bacteria. In 2017, the phenomenon of Streptomyces exploration was described for the first-time as a mechanism of translocation performed by Streptomyces cells through biotic and abiotic surfaces to facilitate access to distant nutrients. It was reported that the incidence of wild-type Streptomyces strains exhibiting exploration was ~10%. In addition, two critical conditions involved in the exploration process were described, glucose depletion and alkaline pH in the medium produced by the synthesis of volatile organic compounds (VOCs). Here, we screened 57 Streptomyces strains previously isolated from four sites in Eastern Antarctica. We found that 22.8% did not exhibit exploration capabilities, and 19.4% showed exploration behaviour in glucose depletion and alkaline environments. In contrast, 57.8% exhibited exploration at neutral pH or in the presence of glucose. These findings about the incidence of glucose-independent exploration suggest that the exploratory behaviour might be encouraged by searching for alternative carbon sources due to the low nutrient availability in East Antarctic soils. The second aim was to provide insight into potential compounds involved in Streptomyces exploration. Here, we obtained a fraction with emulsifying, antimicrobial, and haemolytic activities from the secretome of Streptomyces INR7 explorer cells. LC-MS analysis of the fraction and bioactive predictors revealed that a LysM-containing peptide with amphipathic properties is the responsible for the antibacterial and haemolytic activities. Furthermore, genomic annotation and sequence alignment indicate that the peptide is part of a protein belonging to the resuscitation-promoting factors family, contributing to physiological processes of cell wall remodelling and metabolic activation of dormant cells. The third aim was to describe whether Antarctic Arthrobacter isolates can use microbial hitchhiking as a motility strategy to migrate across the fungal hyphae of Antarctomyces psychrotrophicus. So far, Arthrobacter bacteria have been associated with active motility, also known as flagella-dependent motility. Flagella-assisted displacement is typical in aqueous environments; however, East Antarctic soils are exposed to arid and hyperarid conditions, suggesting that the motility of Arthrobacter isolates from these polar desert soils might be challenging. Here, we found that microbial hitchhiking facilitates the migration of Arthrobacter strains previously isolated from Antarctic soils. Hitchhiking is a form of transportation where microorganisms with null or limited motility, known as 'hitchhikers' or 'riders', use the motility of nearby motile organisms known as 'carriers' or 'host' to move. In soils, fungi facilitate the migration of bacteria over short and long distances by forming 'networks' or 'highways' on which bacteria can travel actively, passively or by direct attachment to the fungal hyphae. By using SEM, motility screening, flagella identification and hitchhiking assays, we found that of 17 Arthrobacter strains examined, 14 migrated through the fungus A. psychrotrophicus. The results suggest that Arthrobacter isolates migrated by three mechanisms: two strains travelled flagella-dependent motility, seven isolates translocated by flagella-independent motility and five strains migrated by direct attachment to the fungal surface. These findings provide evidence that Antarctic soil bacteria, specifically members of the genera Streptomyces and Arthrobacter, exhibit a high incidence of motility. We propose that motility could be a survival strategy used by bacteria to cope with the extreme conditions in Antarctica.

  • (2022) Guan, Peiyuan
    Thesis
    Cathode is the key component in lithium-ion batteries (LIBs) and it determines the performance of LIBs to a large extent. Recently, layered-structure Ni-rich cathode has attracted concentrated research attention due to its high theoretical capacity and energy density, which showed great potential as an alternative for the current dominant LiCoO2 in the energy market. Intrinsically, the high Ni content led to an excellent discharge capacity; however, the high reactivity of Ni also caused an capacity fading resulting from the undesired side reactions during prolonged cycling. Therefore, a trade-off between high capacity and long cycle life obstruction of the commercializing process of Ni-rich cathode in modern LIBs. In this case, this work attempt to employing surface modification strategy to stabilize the cyclability of Ni-rich cathodes by perovskite oxides. Because they provide a variety of outstanding physical and chemical properties. Most importantly, several materials, including metal oxide, fluoride, phosphate, etc. have been investigated as surface coating layer for the electrochemical property enhancement; however, perovskite oxide is still rarely mentioned. THus, this work firstly used a typical perovskite oxide, strontium titanate (STO) and its diverse modified forms, as surface modifier coated onto Ni-rich cathodes, respectively. In detail, chapter 4 demonstrates that the STO surface coating on NCM811 could effectively enhance its cycling stability. The effect of the heat treatment after perovskite oxide surface coating is studied and disclosed in chapter 5. In chapter 6, NCA is covered by STO with the defect-rich surface, exhibiting a better rate performance due to the higher electronic and ionic conductivity possessed by the coating layer. At last, as-prepared Nb-doped STO onto NCM811 could act as a buffer layer to suppress the dissolution of transition metal ions resulting from the electrolyte decomposed HF attacking and robust the Li diffusion channel during the charge-discharge process. The current study offers a systematically understanding of the positive effect of perovskite oxide materials-based surface modification on Ni-rich cathodes. It confirms the feasibility of improving the electrochemical performances of Ni-rich oxides by preventing the deleterious side reactions accompanied by reducing Li residues on the cathode surface, which is of great significance to the optimization of the cathode material for next-generation LIB for electric vehicles.

  • (2023) Dela Cruz, Michael Leo
    Thesis
    Biodegradable implant materials are more appropriate for temporary support applications compared with their inert counterparts since the former requires no removal surgery because they naturally degrade and eventually dissolve completely during healing. Iron and its alloys are a possible substitute for the commercial magnesium biodegradable implants because of their superior mechanical properties and slower corrosion rates. The addition of manganese and silicon in iron imparts another interesting property to the material–the shape memory effect. There is copious research on the structure and properties of the biodegradable face centred cubic (FCC) Fe-30Mn-6Si shape memory alloy (SMA) that exhibits the reversible FCC austenite to hexagonal close packed (HCP) ε-martensite transformation. However, recent advances in additive manufacturing of metals, brought by the development of the laser powder bed fusion (LPBF) technique, warrant the need for an investigation on the adaptability of the technique in fabricating this alloy composition. The LPBF technique is limited by the need for specialty raw material powder, and this thesis extends the application of the technique in fabricating the Fe-30Mn-6Si shape memory alloy (SMA) from homogenised powder precursors. More so, LPBF processing of Fe-30Mn-6Si alloy from either pre-alloyed powder or blended powder has not been reported. To successfully fabricate a Fe-30Mn-6Si LPBF product, the influence of key LPBF processing parameters on product quality was identified as a major challenge. This was addressed by investigating the influence of laser power, laser scan speed, laser re-scanning, and their equivalent input energy on the relative density and defect formation. A relative density of over 99% with few processing defects was achieved using the optimised parameters of 175 W laser power, 400 mm/s scan speed, and no re-scanning. The influence of these parameters on the solidification microstructure was also investigated using key techniques, such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD). Further, the simulated thermal profile of the melt pool region as a function of process parameters via single scan track experiments was calculated using the finite element method (FEM). These data were used to explain the key microstructural features observed in the as-solidified microstructure of the LPBF alloy as a function of the processing parameters. The mechanical properties of the LPBF alloy were then assessed by hardness and tensile testing and then compared with a reference alloy produced by arc melting. The hardness of the LPBF as-built alloy was ∼20% higher than the reference alloy. To identify the factors affecting the increased hardness of the former, the influence of grain size and morphology, crystallographic texture, phase constituents (mainly austenite and martensite), and residual strain were investigated. The hardness of the reference alloy was affected mainly by the grain size and residual strain, but for the LPBF-built alloy, the relative volume fractions of austenite and martensite strongly influenced the hardness. Meanwhile, the tensile properties of the LPBF alloy, such as the yield stress, ultimate tensile stress, and ductility, were adversely affected by the internal defects present, such that high temperature homogenisation and hot isostatic pressing (HIP) post-process treatments were investigated to improve these properties. The homogenisation and HIP treatments increased both the tensile strength and ductility of the LPBF-built alloy. Homogenisation altered the grain morphology by promoting recrystallisation and grain growth, and this increased the tensile strength by ∼80%. The hardness, however, decreased due to a reduction in the volume fraction of HCP martensite in the FCC austenitic microstructure. HIP retained some of the columnar microstructure generated by the LPBF process, marginally increased the density, and increased the tensile strength by ∼65%. The improvement in tensile properties through these post-process treatments allowed for the measurement of LPBF alloy’s shape memory behaviour, whereby a tensile recovery strain of 2% was achieved for the HIP-treated alloy. Finally, the biocorrosion behaviour of the LPBF-processed and HIP-treated alloy was investigated, whereby the in vitro corrosion potential and current density of the alloy were determined to be -769 mV and 5.6 μA/cm2, respectively, indicating a reasonable corrosion rate for this material. Overall, this thesis enabled the first demonstration of the shape memory effect in an LPBF-built Fe-based alloy fabricated from homogenised powder, an alloy which also exhibits biodegradable properties.

  • (2022) Nguyen, Thi Cam Phu
    Thesis
    The study of mechanical properties of materials (stiffness, toughness, and so on) using scanning probe microscopy (SPM) methods has received increased interest over the past few years. Atomic force microscopy (AFM) is an SPM method to image different properties of a wide range of materials down to the atomic scale. This thesis focuses on an in-depth description of various AFM-based methods to characterize the mechanical properties of biomaterials and ferroic materials on the nanometer scale. The high-order structures that form natural hierarchical shapes are claimed to be the main factor to enhance the extraordinary mechanical properties of biological structures. In this thesis, we are using three different types of AFM-based techniques (consisting of contact resonance force microscopy, force-distance map, and nanoindentation) and related fitting methods to analyse the mechanical properties of two different biomaterials, including (1) Paua abalone shell and (2) Tonkin bamboo. By combining those methods, we affirm the quantitativeness of our mechanical measurements. The obtained results reveal the detailed mechanical properties of the hierarchical structure of biomaterials and provide a strategy for accurately testing the nanoscale mechanical properties of advanced composite materials. To investigate the pressure-induced mechanical changes on the ferroelectric lead titanate, PbTiO3, single crystal, we used AFM methods to characterize the ferroelectric 90- and 180-degree in-plane and out-of-plane domain walls and observe that, despite their separation mechanically identical domains, the walls appear different in mechanical responses compared to the domains. Moreover, for the first time, we study the crackling noise concept at the length scale of a few nanometres of the ferroelectric PbTiO3 domain wall. It represents that the ultimate functional feature can be potentially exploited for new concepts in information storage and processing, sensing, and actuating. In general, these results indicate that SPM methods can provide comprehensive information and a deep insight into unique properties in a wide range of materials and their applicability in nanoscale regimes, and guide new developments on promising nanoscale devices.

  • (2023) Zhou, Yingze
    Thesis
    In recent years, the urgent need for efficient energy technologies such as electrocatalysis and energy storage has attracted great attention around the world. Among them, the electrocatalytic is one of the most promising green hydrogen production approaches. For consideration of limited earth reserves, exploring the earth-abundant non-noble metal catalysts for highly efficient is necessary. Manganese-based electrocatalysts including manganese oxides and manganese sulphides are promising candidates owing to their high natural abundance and cheap price. However, some key factors such as exploring facile and effective methods to synthesize Mn-based catalysts, optimize the phase and morphology, enrich the active sites and vaccines, and control the electronic structure still need deep study in the current stage. Compared to the hydrogen evolution reaction (HER) process, the oxygen evolution reaction (OER) process requires the transfer of four electrons with a higher reaction energy barrier. It is very important to investigate the highly efficient OER catalysts to break through the technology of hydrogen production from overall electrocatalytic. Hence, in this work, the controllable phases of MnO2 catalysts for bifunctional water splitting, the modified MnO2 catalyst with rich oxygen vacancies for OER, Co doped MnO catalyst for OER and MnS/Ni3S2 catalyst for OER have been designed and deeply studied. The as prepared samples show superior catalytic performance with low overpotential, small Tafel slopes, enhanced conductivity, and outstanding durability. The mechanisms of enhanced electrocatalytic performance have been investigated as well. It is found that both crystalline structures and electronic structures have a strong effect on the catalytic performance of Mn-based catalysts. Firstly, the phases and morphologies directly affect the exposure of the active sites. Secondly, the high content of Mn3+ sites and oxygen vacancies could be highly improved the water splitting performance. Thirdly, superior band alignment tunability allows for efficient improvement of the electrocatalytic performance. Finally, the specific element doping results in the lower work function could accelerate the charge transfer process of the OER activity. This work has demonstrated feasible ways to fabricate efficient electrocatalysts, which may provide key strategies to design advanced metal oxides for practical water splitting devices in the future.