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Mechanical performance of hybrid fibre reinforced magnesium oxychloride cement-based composites at ambient and elevated temperature
No full textMagnesium oxychloride cement (MOC) is often recognized as an eco-friendly cement and has found widespread application in various sectors. However, research on its resistance against elevated temperatures including fire is very limited. This paper thoroughly investigated the mechanical performance of fibre reinforced MOC-based cementitious composite (FRMOCC) at ambient and elevated temperatures. A recently developed water-resistant MOC was used as the base matrix which was further reinforced using hybrid basalt and polypropylene fibres at various proportions, and a systematic study on the effect of fibre dosage on compressive and tensile strength of FRMOCC was conducted. The specimens were exposed to elevated temperatures ranging from 200 to 800 °C; mechanical performance and phase composition from a microscale study were analysed. The findings revealed that compressive strength, with the increase in temperature, substantially decreased, with values of 30–87% at 400 °C and over 95% at 800 °C. Specimens with 1.5% basalt and 0.5% PP fibre showed the least reduction possibly due to the vacant channels created as a result of the melting effect of PP fibres. Tensile strength was also completely lost at 600 °C and the specimens suffered substantial mass loss exceeding 30% at this temperature, indicating significant matrix decomposition. Additional analysis using X-ray diffraction (XRD) and scanning electron microscope (SEM) revealed the decomposition stages of the matrix and highlighted the instability of the main hydration phases of FRMOCC at elevated temperatures
A sky full of stars, constellations, satellites and more! : legal issues for a ‘dark’ sky
No full textAn ever-increasing number of actors, including private entities, are conducting space activities that involve the launch of spacecraft into orbit. The ‘miniaturisationʼ of technology has meant that this now includes the launch of large constellations of small satellites. Notwithstanding their commercial benefits, the deployment of large numbers of objects into Low Earth Orbit raises concerns for elements of the international space community specifically concerned with the protection of the ‘darkʼ skies. Large constellation programmes and space debris reflect sunlight into astronomical telescopes or cross their field of view, in many instances degrading certain astronomical observations which would otherwise support our capacity to understand the universe, enable deep-space navigation and exploration and provide early warning detection of near-Earth objects. The various differing interests at stake represent challenges in the application of international environmental law as well as for the current space legal framework, especially for the preservation of the space environment and the long-term sustainability of space activities. Considering the congested space environment and the need to preserve the ‘darkʼ skies for astronomical observation, establishing space traffic management rules and standards is of particular importance
Impact assessment of the Australian 2019-20 megafires on roost sites of the vulnerable grey-headed flying-fox (Pteropus poliocephalus)
No full textBushfires are a natural component of the ecology of many landscapes, but megafires such as those experienced in Australia between July 2019 and April 2020 have substantial direct and indirect impacts on wildlife. Following these megafires, bushfires have begun to be considered a significant emerging threat to the vulnerable grey-headed flying-fox (Pteropus poliocephalus). In this study, we quantified the impact of the 2019–20 megafires on all known roost locations of the species by (1) determining the number of roosts within burnt areas represented by three fire severity mapping products, (2) classifying burnt roosts according to the severity with which they burnt, and (3) examining the distribution of distances to the nearest burnt areas for unburnt roosts. Our findings indicate that the impacts of the 2019–20 megafires on roosting habitat of the grey-headed flying-fox have hitherto been underestimated. Of 874 known grey-headed flying-fox roosts, we found that 134 roosts were situated within burnt areas, equating to 15 % of the species’ roost locations. Depending on the mapping products applied, part or all canopy vegetation was severely burnt in 27–36 % of burnt roosts, while in 11–14 % of burnt roosts, the canopy vegetation was burnt entirely. Of the 740 unburnt roosts, 50 % were located within 6.85 km from burnt areas, suggesting that, at a substantial number of roosts, flying-foxes were also indirectly affected by the fires, through the effects of smoke on roosting and locally foraging individuals, and through destruction of local foraging resources from burning. We discuss the implications of these findings for the conservation management of this vulnerable species
[In Press] Building emotional resilience to foster well-being by utilising reflective practise in the sonography workplace
No full textReflection and reflective practise are well recognised tools that are utilised by healthcare professionals to support self-awareness and self-care. In turn, self-care is a critical component of the wellbeing and the capacity for resilience of healthcare professionals in response to day-to-day exposure to emotionally and psychologically challenging situations. Affective reflection, the process of considering and analysing thoughts, feelings and emotions though written dialogue (the act of reflective writing), has been shown to be beneficial for promoting and building resilience in healthcare professionals. Despite the known benefits of these strategies for maintaining wellbeing and avoiding compassion fatigue and burnout, the discourse on the use of affective reflection and reflective writing in the sonography profession is limited. Interventions such as reflection, reflective practise and reflective writing should not be underestimated as tools to promote the adaptive abilities and the degree of individual emotional resilience of sonographers. Long term positive outcomes supported by utilising and practising reflection include the maintenance of emotional stability and an increase in the scope for empathy and subsequently, an enhancement of quality of practise and patient care. This article aims to provide a broad discussion on the practise of affective reflection and showcase the process of reflective writing using written reflective dialogue guides with practical examples relevant to sonography practise. In addition, this paper outlines how these strategies can be incorporated and enacted in the sonography workplace to build resilience
Barriers to the diagnosis and management of keratoconus among optometrists in Kenya
No full textBackground: Early diagnosis and management of keratoconus (KC) are important for limiting visual complications of the disease. This study aimed to explore the perspectives of optometrists on the barriers to effective diagnosis and management of KC in Kenya. Methods: An online questionnaire was distributed to optometrists in Kenya to collect data on barriers to the diagnosis and management of KC. Results: The majority (60.9%) of optometrists were confident in retinoscopy and subjective refraction. Fewer were confident in the use of keratometers (46.4%) and corneal topographers (24.9%) and in the fitting of rigid gas permeable (RGP) contact lenses (25.0%). The most commonly reported barriers to improving their knowledge and skills were, limited continuous professional development opportunities (87.4%), high costs of conferences (86.1%) and the lack of diagnostic tools (79.5%). Impediments cited to diagnosing and managing KC effectively were a lack of national guidelines (64.9%), patient education material (71.5%), equipment (58.9%) and RGP supply (68.2%) and cost (67.5%). Most commonly reported barriers related to patients were compliance (91.4%), affordability (90.7%), RGP discomfort (89.4%), willingness to pay (88.1%) and the lack of patient education about KC (87.4%). Conclusion: This study showed that the lack of national guidelines, essential equipment and adequate practitioner knowledge and skills were barriers to KC diagnosis and management. Regulation of optometric education and clinical practice, development of national guidelines for diagnosis and management of KC, up-skilling of practitioners and cost-effective solutions for equipment procurement and maintenance may improve both access to, and quality of, care to patients with KC
Neural activity of retinal ganglion cells under continuous, dynamically-modulated high frequency electrical stimulation
No full textObjective. Current retinal prosthetics are limited in their ability to precisely control firing patterns of functionally distinct retinal ganglion cell (RGC) types. The aim of this study was to characterise RGC responses to continuous, kilohertz-frequency-varying stimulation to assess its utility in controlling RGC activity. Approach. We used in vitro patch-clamp experiments to assess electrically-evoked ON and OFF RGC responses to frequency-varying pulse train sequences. In each sequence, the stimulation amplitude was kept constant while the stimulation frequency (0.5-10 kHz) was changed every 40 ms, in either a linearly increasing, linearly decreasing or randomised manner. The stimulation amplitude across sequences was increased from 10 to 300 µA. Main results. We found that continuous stimulation without rest periods caused complex and irreproducible stimulus-response relationships, primarily due to strong stimulus-induced response adaptation and influence of the preceding stimulus frequency on the response to a subsequent stimulus. In addition, ON and OFF populations showed different sensitivities to continuous, frequency-varying pulse trains, with OFF cells generally exhibiting more dependency on frequency changes within a sequence. Finally, the ability to maintain spiking behaviour to continuous stimulation in RGCs significantly reduced over longer stimulation durations irrespective of the frequency order. Significance. This study represents an important step in advancing and understanding the utility of continuous frequency modulation in controlling functionally distinct RGCs. Our results indicate that continuous, kHz-frequency-varying stimulation sequences provide very limited control of RGC firing patterns due to inter-dependency between adjacent frequencies and generally, different RGC types do not display different frequency preferences under such stimulation conditions. For future stimulation strategies using kHz frequencies, careful consideration must be given to design appropriate pauses in stimulation, stimulation frequency order and the length of continuous stimulation duration
[In Press] Considerations of communication challenges facing sonographers in Australia beyond 2024 : an ageing population, ageism and maintaining the focus on patient-centred care
No full textIn the coming decades, the number of people in the Australian population over the age of 65 is predicted to increase to 23% by the year 2066. The process of physiological ageing is associated with an increase in the presentation of disease pathologies, an increased potential for physical and cognitive deficits and a decrease in health literacy. The ageing of the Australian population presents challenges for the sonography profession including an increasing age gap between the sonographer and their patient as well as increasing complexities in performing ultrasounds on older patients. The natural changes that accompany ageing can create barriers to effective communication between sonographers and their patients. Ageist beliefs can lead to conscious and unconscious bias and unfounded judgements by sonographers decreasing the quality of patient care. To combat the decline in the quality of healthcare that is reported for older patients, sonographers can endeavour to put into place deliberate practical tools and strategies to avoid ageism and improve communication with older patients. Conversely, institutional awareness, education and policies that address age related judgements and bias from older patients towards younger sonographers can foster respectful dialogue, promote understanding and stimulate positive communication across different age groups
Agroecological consequences of silicon supplementation for a legume cultivation : two-year-long field observations
No full textSupplementing plants with silicon (Si) often improves plant productivity and resilience to biotic and abiotic stresses, but this is mostly reported in highly controlled experimental environments. The ecological consequences of Si supplementation, including environmental benefits and potential risks, are therefore poorly understood and require field-scale evaluation of how Si supplementation affects the wider ecosystem, such as invertebrate communities and soil physicochemical properties. We conducted the first field assessment of how a legume (lucerne; Medicago sativa) agroecosystem and its associated invertebrate communities responded to two levels of Si supplementation (calcium silicate slag), over two years. We quantified seasonal changes in the abundance and diversity of aboveground arthropod communities, crop yield, elemental and nutritional chemistry, and soil pH as well as soil chemistry. The highest rate of Si supplementation increased bioavailable Si in the soil by 181% and soil pH from 5.2 to 6.3, relative to untreated plots, with a significant positive correlation between increased soil bioavailable Si and pH. Si supplementation led to an increase in crop yield by up to 52%; however, the magnitude varied with season. Foliar concentrations of Si tended to increase with Si supplementation, but this increase was marginally significant, potentially due to a dilution effect of higher shoot biomass. Si supplementation did not affect concentrations of most soil elements we quantified or forage quality of lucerne. We recorded over 13,600 arthropods; Si supplementation led to a shift in community structure and overall increased diversity of arthropod functional groups. Notably, the saprophytic fly family, Lauxaniidae was more abundant on Si-supplemented plots compared to untreated plots, potentially due to increased plant turnover. These results indicate that silicon supplementation of a legume agroecosystem, using a by-product of steel production, provides productivity benefits that outweigh some possible detrimental impacts on the ecosystem (i.e. decreased arthropod abundances, toxic metal contamination or reduced forage quality), which we did not detect in our current field study. This management intervention enhances crop yield, so could reduce the need for conventional fertilisers as well as changing soil pH to be more beneficial to crops and some arthropod groups
Health benefits of Allium spp. in metabolic syndrome : a review
No full textAllium species have been recommended in traditional medicine for its efficacy in treating a variety of diseases such as arthritis, cardiovascular and kidney diseases, diabetes, colds, flu, headache, cough, hemorrhage, atherosclerosis, asthma, cancer, colic and skin problems Notably, it has shown promise in mitigating inflammation, regulating blood sugar levels and reducing oxidative damage. Metabolic syndrome, a cardiovascular risk factor characterized by a cluster of metabolic irregularities, including obesity, dyslipidemia, hypertension, and type 2 diabetes mellitus, often precipitates insulin resistance and development of cardiovascular disease or diabetes. This review endeavors to explore the role of various Allium species on different aspect of metabolic syndrome. Bibliographic databases, including PubMed and Scopus, Science Direct and Google Scholar databases were searched for the collection of relevant information. The abundant biological benefits of Allium species against the metabolic syndrome can be attributed to compounds such as flavonoids, steroidal saponins, stilbenoids and organosulfur compounds (OSCs). Both extracts and isolated compounds have exhibited efficacy in reducing internal mediator of hypertension, cholesterol, triglycerides and low-density lipoprotein, showcasing favorable attributes in weight management and type 2 diabetes control. Organosulfur compounds, steroidal saponins and phenolics are among the large number of active components of the genus Allium, displaying multiple pharmacological actions, which are supported by in vitro, in vivo and clinical studies. Nevertheless, while the existing body of evidence underscores the potential of Allium genus and its active components in managing complications associated with metabolic syndrome, further clinical trials are warranted to support their efficacy and safety for clinical application
Abiotic stress treatment reveals expansin like A gene OfEXLA1 improving salt and drought tolerance of Osmanthus fragrans by responding to abscisic acid
No full textSweet osmanthus (Osmanthus fragrans) is a having general approval aromatic tree in China that is widely applied to landscaping and gardening. However, the evergreen tree adaptability is limited by many environmental stresses. Currently, limited information is available regarding the genetic analysis and functional identification of expansin genes in response to abiotic stress in sweet osmanthus. In this study, a total of 29 expansin genes were identified and divided into four groups by genome-wide analysis from the sweet osmanthus genome. Transcriptome and quantitative Real-time PCR analysis showed that the cell wall-localized protein expansin-like A (OfEXLA1) gene was significantly induced by salt and drought treatment. Histochemical GUS staining of transgenic Arabidopsis lines in which GUS activity was driven with the OfEXLA1 promoter, GUS activity was significantly induced by salt, drought, and exogenous abscisic acid (ABA). In yeast, we found OfEXLA1 overexpression significantly improved the population of cells compared with wild-type strains after NaCl and polyethylene glycol (PEG) treatment. Additionally, OfEXLA1 overexpression not only promoted plant growth, but also improved the salt and drought tolerance in Arabidopsis. To gain insight into the role of ABA signaling in the regulation of OfEXLA1 improving abiotic tolerance in sweet osmanthus, four differentially expressed ABA Insensitive 5 (ABI5)-like genes (OfABL4, OfABL5, OfABL7, and OfABL8) were identified from transcriptome, and dual-luciferase (dual-LUC) and yeast one hybrid (Y1H) assay showed that OfABL4 and OfABL5 might bind to OfEXLA1 promoter to accumulate the OfEXLA1 expression by responding to ABA signaling to improve abiotic tolerance in sweet osmanthus. These results provide the information for understanding the molecular functions of expansin-like A gene and molecular breeding of sweet osmanthus in future