220861 research outputs found
Sort by
Dual fiber probe with 3D-printed micro-lens for Brillouin microscopy
No full textPublished Online: 15 April 2025Brillouin spectroscopy is a powerful technique for non-invasive micromechanical analysis of biological materials such as tissues and cells. Conventional bulk-optical Brillouin spectroscopy systems, however, face challenges in translation to endoscopic applications due to strong parasitic background signals using single optical fibers. To overcome this issue, dual fiber approaches have been proposed, but they suffer from poor overlap of excitation and collection beam paths. In this work, we present a dual fiber-integrated probe with a tip diameter below 300 μm. Using tailored freeform 3D-printed micro-optics, we achieve a precise overlap of the foci to map mechanical properties with a resolution below 10 μm in lateral and 45 μm in axial direction. We detail the probe's design, fabrication, and optical simulations and present experimental results demonstrating high-resolution Brillouin measurements from polymer and protein solution samples. Our findings indicate that this dual fiber probe could significantly advance fiber-integrated Brillouin spectroscopy, with promising applications in materials science and biomedical diagnostics.Joshua Trapp, Hadi Mahmodi, Marco Wende, Luke McAlary, Lezanne Ooi, Jiawen Li, Robert A. McLaughlin, Alois Herkommer, Andrea Toulouse, and Irina Kabakov
Micromechanical characteristics of titanium alloy (Ti-6Al-4V) made by laser powder bed fusion using an in-situ SEM micropillar compression technique
No full textWhile titanium alloy (Ti-6Al-4V) made by laser powder bed fusion (L–PBF) exhibits complex deformation behaviors, its important micromechanical properties in relation to loading directions are not fully understood. This research aims to investigate the micromechanical behaviors of printed L–PBF Ti-6Al-4V alloys under vertical (i. e., the loading direction perpendicular to printed layers) and horizontal (i.e., the loading direction parallel to printed layers) compressions using in-situ scanning electron microscopy (SEM) micropillar techniques. Ti-6Al-4V alloys were L-PBF-printed using a 45◦ rotate scanning strategy with vertical and horizontal build directions. The microstructures of the two alloys were analyzed using the SEM with energy-dispersive X-ray spectroscopy (EDS). The titanium alloy micropillars were produced using focused ion beam (FIB) milling in the SEM. In-situ SEM micropillar compressions were conducted using a flat diamond indenter. Vertical alloy had smaller crosspatterned finer α′ martensite than horizontal one. While both vertical and horizontal micropillars showed elastic-plastic behaviors, the former had significantly higher yield, fracture, and compression strength values, as well as resilience and toughness, than the latter, leading to the formation of favorable shear bands. Both micropillars exhibited ductile fractures but had distinct failure mechanisms. The ductile fracture in the vertical micropillars was due to strain hardening, large plastic deformation, and shear band formation, while the ductile fracture in the horizontal ones was attributed to compression-induced bending and plastic buckling. The micromechanical characteristics of L–PBF Ti-6Al-4V materials provides an important insight into the small-scale deformation and failure mechanisms of the alloys influenced by loading directions.Md Bengir Ahmed Shuvho, Afifah Z. Juri, Animesh K. Basak, Andrei Kotousov, Ling Yi
After Images: 60 Years of Australian Dance Theatre
No full textAfter Images has been curated by Dr Maggie Tonkin, Associate Professor Cheryl Stock, Professor Rachel Fensham, Siobhan Murphy and Adrianne Semmen
Highly Sensitive Fiber Optic Sensor for Simultaneous Refractive Index and Temperature Measurement Using Suspended Core Fiber
No full textA novel fiber optic sensor has been developed using suspended core fiber (SCF) to simultaneously measure the refractive index (RI) and temperature of liquids. The innovative design comprises an SCF segment spliced between two tapered single-mode fibers (SMFs). The SCF allows the transmission of multiple modes, thus enabling multimode interference. Importantly, the three internal holes of the SCF function as microfluidic channels, providing direct access to the evanescent field of the micrometer-scaled core. This direct interaction significantly enhances the sensor’s sensitivity by intensifying the light-sample interaction. Each pair of interfering optical modes exhibits distinct sensitivity to both temperature and RI. By performing Fourier analysis, the interference spectrum for each mode pair can be extracted. High sensitivity is achieved, with the values of 1560 and 1217 nm/RIU for RI within the range 1.3309–1.3350 and −0.25 nm/°C and −0.31 nm/°C for temperatures ranging from 20 °C to 40 °C. The resolutions of RI and temperature were 1.3×10‾⁵ RIU and 0.06 °C, respectively. The transfer matrix method effectively eliminates temperature interference during RI measurement, ensuring reliable and accurate RI readings. The sensor is shown to have a detection limit as low as 6.1×10¯⁵ RIU and 0.3 °C. Combining its desirable characteristics of good stability, a simple structure, and high sensitivity, this novel sensor holds significant promise for diverse applications in environmental monitoring, medical testing, and biological sensing.Xindi Zhang, Xue Zhou, Yanan Zhang, Linh Viet Nguyen, Yong Zhao, Stephen C. Warren-Smith, and Xuegang L
Toward Piezoresistive Devices That Exploit Bullvalene's Structural Versatility
No full textBullvalene is the archetypical “shape shifting” molecule, undergoing continuous Cope rearrangements in solution at room temperature at a rate of about 3 kHz. In the confined spaces of an scanning tunneling microscopy break junction (STMBJ) setup, isolated bisarylbullvalene molecules have recently been shown to exhibit very restricted isomerization and slower interconversion rates. The restricted number of populated bullvalene isomers displayed large variances in conductivity with the confinement to manifest high piezoresistivity. Herein, the confinement is increased by forming self-assembled monolayers (SAMs), focusing on measuring the resulting electron-transfer rates, as well as identifying viable SAM structural possibilities. First, bis-4-phenyl acetylene bullvalene was synthesized and its SAMs were produced on Au(111). Redox active ferrocene tail groups were then attached via a copper catalyzed azide–alkyne cycloaddition (CuAAC) to enable electrochemical measurements of SAM coverages and electron-transfer rates. The results are consistent with only a single isomeric form being present on the surface at any one time, with its nature varying with monolayer coverage density. Density functional theory (DFT) simulations indicate that a combination of steric interactions induced by the bisarylbullvalene substitution, combined with head group and SAM packing effects, results in this coverage-dependent isomeric selectivity. A small number of very different types of SAM structural possibilities are identified. These findings provide a pathway forward for the exploitation of bullvalene’s constitutional isomerism in facilitating nano-electromechanical systems (NEMS).Tiexin Li, Zane Datson, André P. Birvé, Simone Ciampi, Thomas Fallon, Daniel S. Kosov, Jeffrey R. Reimers, Nadim Darwis
Drivers of Spring Emergence and Abundance of the Australia Sheep Blowfly Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) on Kangaroo Island
No full textLucilia cuprina (Wiedemann) is an invasive species of blowfly and the primary instigator of sheep flystrike, the dermal infestation of a live animal with Dipteran larvae. As a significant pest to the Australian wool industry, the South Australian government and industry partners are developing an eradication program for L. cuprina on Kangaroo Island (KI), South Australia, using the Sterile Insect Technique (SIT). SIT suppresses reproduction by mass-rearing and releasing sterilised insects into a wild population. To enhance eradication efforts, two areas of the blowfly’s ecology were studied on KI. The first study investigated the drivers of spring emergence, a period when population numbers are low and fewer sterile insects are needed for outnumbering. Adult fly emergence from post-feeding larvae released in autumn and winter on KI was compared to soil temperature and soil moisture content. Analysis of emergence timing showed temperatures below 15.8C suppressed emergence. Rate of emergence and survival were positively associated with mean soil temperature 31-60 days post-release, and larvae that spent less time in the soil overwintering had a higher chance of survival. The second study investigated the distribution and relative abundance of L. cuprina on KI through a 9-week relative abundance survey. Four main habitat types are present on KI: Broadacre Agriculture (BA), Conservation and Plantation Forestry (CPF), Sheep Grazing (SG), and Urban (U). We installed a network of 81 novel semiochemical-baited traps across 27 sites within these habitat categories, identifying L. cuprina and eight sympatric blowfly species from the trap catch. We detected L. cuprina in all four habitats at varying abundance, with a clear association with SG sites. The presence of L. cuprina in the centre of isolated CPF areas where sheep are absent suggests the species can compete with some success with other necrophagous insects on carrion, and/or utilise other live animals as hosts. Their detection in these sites may also be indicative of sex-biased migratory behaviour.Thesis (MPhil) -- University of Adelaide, School of Biological Sciences : Ecology and Evolutionary Biology, 202
Effectiveness of air polishing as a method of oral prophylaxis in the orthodontic setting: a systematic review with meta-analysis
No full textIntroduction: There are a growing number of people of all ages who receive orthodontic care to correct aspects of dental malalignment. Maintaining optimal oral hygiene is crucial for achieving successful outcomes and preventing deterioration of dental health caused by inadequate plaque removal during orthodontic interventions. This systematic review aimed to evaluate the effectiveness of air powder polishing (APP) as a method of oral prophylaxis on orthodontic patients and where possible compare its effectiveness with traditional prophylaxis methods. A systematic review is essential to evaluate APP's efficacy in cleaning patients' soft and hard tissues as well as orthodontic appliances within the clinical orthodontic context. Methods: A systematic review was conducted using the JBI methodology for quantitative systematic reviews. The review considered experimental and observational studies that investigated the effectiveness of APP in adolescents and adults undergoing orthodontic treatment. Studies that compared APP with any other methods of oral prophylaxis were included as were those studies that compared APP with no intervention, and those that compared unpolished orthodontic wires with air polished wires. A range of outcomes were considered including plaque index, stain index, time efficiency, Streptococcus mutans count, comfort/convenience and debris levels. The search for published studies was conducted in PubMed, Embase, Dentistry and Oral Science Services (DOSS) and Cochrane Central Register of Controlled Trials. Unpublished studies were sought through ProQuest Dissertations and Theses, Clinicaltrials.gov and Cochrane Central Register of Controlled Trials. Eligible studies were critically appraised using the standardised JBI critical appraisal instrument for randomised controlled trials (RCTs), and data extraction was performed using the JBI standardised data extraction tool. Meta-analysis, when appropriate, was conducted alongside a narrative synthesis of the findings. Results: Six RCTs were included in the review. Results of this review suggest that both APP and RCP (rubber cup and paste) are effective for oral prophylaxis, although the APP method is more efficient, taking less time to perform. Combined studies yielded a statistically significant difference in favour of APP over RCP in terms of the time efficiency outcome. The plaque index was also favourable for APP, indicating a statistically significant reduction in plaque levels compared to RCP. Conclusion: This systematic review suggests that orthodontic patients of any age with orthodontic appliances may benefit from using APP for oral prophylaxis during their treatment. While both APP and RCP are effective methods, APP has the advantage of requiring less time to perform. However, the review included only six studies, limiting the data available to demonstrate the effectiveness of the outcomes assessed. Of these outcomes, only treatment time could be meta-analysed, which was based on three studies. The limited number of studies reflects a general lack of primary research on this topic. Future trials with longer follow-up times are recommended to better assess the long-term effectiveness of APP.Thesis (MClin.Sci.) -- University of Adelaide, School of Public Health : JBI, 202
Antibody responses against influenza A decline with successive years of annual influenza vaccination.
No full textInfluenza vaccine effectiveness and immunogenicity can be compromised with repeated vaccination. Weassessedimmunological markers in a cohort of healthcareworkers (HCW) from six public hospitals around Australia during 2020–2021. Sera were collected pre-vaccination and ~14 and ~180 days postvaccination and assessed in haemagglutination inhibition assay against egg-grown vaccine and equivalent cell-grown viruses. Responses to vaccination were compared by the number of prior vaccinations. Baseline sera were available for 595 HCW in 2020 and 1031 in 2021. 5% had not been vaccinated during five years prior to enrolment and 55% had been vaccinated every year. Postvaccination titres for all vaccine antigens were lowest among HCW vaccinated in all 5-prior years and highest among HCW with 0 or 1 prior vaccinations, even after adjustment. This was observed for both influenza A subtypes and was dependent on pre-vaccination titre. Expanded cohorts are needed to better understand how this translates to vaccine effectiveness.Sheena G. Sullivan ... Helen Marshall ... et al
Antenna-Coupled Micro-Electromechanical Bolometer for Terahertz Detection
No full textThe terahertz sensing and imaging applications require room temperature terahertz detectors that are fast and highly sensitive. In this paper, we introduce a microelectromechanical bolometer coupled with an antenna to improve detection sensitivity by increasing the effective absorption area for terahertz waves. The absorption of terahertz waves heats up the antenna element causing thermal expansion, which affects the natural mechanical resonance frequency of the antenna. The frequency shift can be measured using a laser vibrometer. Additionally, the spiral antenna structure is insensitive to the direction of linear polarization. Overall, the proposed bolometer can achieve improved responsivity with relatively simple design.Sakib Quader, Christophe Fumeaux, Withawat Withayachumnanku
The Influence of Metabolic Substrates and Inflammatory Cytokines on Retinal Pigment Epithelium Metabolism
No full textThe metabolic interplay between the retinal pigment epithelium (RPE) and photoreceptors is essential for maintaining retinal homeostasis. The RPE functions as a metabolic intermediary, regulating nutrient fluxes to support photoreceptor function while maintaining flexibility to adapt to a dynamic metabolic environment. Disruptions in this metabolic equilibrium have been implicated in age-related macular degeneration (AMD), a leading cause of vision loss. This work explores the metabolic plasticity of the RPE in response to nutrient availability and inflammatory cytokines, using a combination of ARPE-19 cells, primary human RPE cells, and ex vivo rat eyecups. To facilitate metabolic analysis, this work also develops cost-effective methodologies for targeted metabolite analysis. Employing colorimetric, fluorometric, and luciferase-based assays, robust and sensitive detection of glucose, lactate, ATP/ADP, and NADH/NAD+ was achieved in ARPE-19 and HepG2 cells, providing a low-cost and technically accessible alternative to metabolomics techniques. Specific metabolic substrates were found to induce distinct effects on RPE glucose metabolism, bioenergetics, and metabolic gene expression. Lactate suppresses glucose consumption while enhancing oxidative phosphorylation (OXPHOS), whereas glutamine sustains mitochondrial respiration in glucose-deprived conditions, positioning it as an alternative metabolic substrate. BSA-conjugated palmitate and retinyl palmitate exert opposing effects, with BSA-palmitate promoting OXPHOS and fatty acid oxidation, while retinyl palmitate increases glycolysis and suppresses mitochondrial respiration. These insights highlight the metabolic adaptability of the RPE in response to nutrient fluxes and its role in maintaining photoreceptor energy homeostasis. Inflammatory cytokines were also found to modulate RPE metabolism. The effects of four key cytokines—TNFα, TGF-β2, IL-6, and IL-1β—were investigated, along with a cytokine cocktail comprising all four cytokines. Cytokine-specific metabolic alterations were observed, including increased lactate production, glucose consumption, mitochondrial volume, and ATP production, with the combined cytokine cocktail exerting the most pronounced effects. A comprehensive comparison of ARPE-19 cells and rat eyecups revealed fundamentally distinct metabolomes, with ARPE-19 cells exhibiting greater sensitivity to inflammatory cytokines, particularly TNFα, while eyecups responded more robustly to TGF-β2. These findings highlight the critical role of model selection in studying RPE metabolism and emphasize the broader implications of inflammation-induced metabolic changes in the RPE, particularly in the context of AMD pathogenesis. Collectively, this work advances our understanding of RPE metabolism under physiological and pathological conditions, elucidating the metabolic consequences of nutrient dynamics and inflammation in the outer retina. These findings offer critical insights into AMD pathophysiology and identify potential therapeutic targets to mitigate metabolic dysfunction in retinal degenerative diseases.Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 202