Browsing by Author "Davies, J"

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    Flexible polymer X‑ray detectors with non-fullerene acceptors for enhanced stability: Toward printable tissue equivalent devices for medical applications
    (American Chemical Society (ACS), 2021-12-08) Large, MJ; Posar, JA; Mozer, AJ; Nattestad, A; Alnaghy, S; Carolan, M; Sellin, PJ; Davies, J; Pastuovic, Z; Lerch, MLF; Guatelli, S; Rosenfeld, AB; Griffith, MJ; Petasecca, M
    There is growing interest in the development of novel materials and devices capable of ionizing radiation detection for medical applications. Organic semiconductors are promising candidates to meet the demands of modern detectors, such as low manufacturing costs, mechanical flexibility, and a response to radiation equivalent to human tissue. However, organic semiconductors have typically been employed in applications that convert low energy photons into high current densities, for example, solar cells and LEDs, and thus existing design rules must be re-explored for ionizing radiation detection where high energy photons are converted into typically much lower current densities. In this work, we report the optoelectronic and X-ray dosimetric response of a tissue equivalent organic photodetector fabricated with solution-based inks prepared from polymer donor poly(3-hexylthiophene) (P3HT) blended with either a non-fullerene acceptor (5Z,5′Z)-5,5′-((7,7′-(4,4,9,9-tetraoctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(benzo[c][1,2,5]thiadiazole-7,4-diyl))bis(methanylylidene))bis(3-ethyl-2-thioxothiazolidin-4-one) (o-IDTBR) or a fullerene acceptor, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Indirect detection of X-rays was achieved via coupling of organic photodiodes with a plastic scintillator. Both detectors displayed an excellent response linearity with dose, with sensitivities to 6 MV photons of 263.4 ± 0.6 and 114.2 ± 0.7 pC/cGy recorded for P3HT:PCBM and P3HT:o-IDTBR detectors, respectively. Both detectors also exhibited a fast temporal response, able to resolve individual 3.6 μs pulses from the linear accelerator. Energy dependence measurements highlighted that the photodetectors were highly tissue equivalent, though an under-response in devices compared to water by up to a factor of 2.3 was found for photon energies of 30-200 keV due to the response of the plastic scintillator. The P3HT:o-IDTBR device exhibited a higher stability to radiation, showing just an 18.4% reduction in performance when exposed to radiation doses of up to 10 kGy. The reported devices provide a successful demonstration of stable, printable, flexible, and tissue-equivalent radiation detectors with energy dependence similar to other scintillator-based detectors used in radiotherapy. © 2021 American Chemical Society.
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    The new external ion beam capability for testing of electronics suitable for harsh space radiation environments
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2021-11-24) Peracchi, A; Cohen, DD; Pastuovic, Z; Paneras, N; Button, DT; Hall, CJ; Davies, J; Mann, M; Cookson, DJ; Hotchkis, MAC; Brenner, CM
    In 2019, the Australian Space Agency made its debut in the international scene of the space exploration. Securing the future of Australia’s space sector is the core of the Advancing Space: Australian Civil space Strategy 2019-2028. This Government plan reminds that space-based technology and services not only interests space missions, but benefits all Australians daily as for weather forecasting, GPS, internet access, online banking, emergency response tracking bushfires, monitoring of farming crops, etc. To further increase capability, the Space Infrastructure Fund (SIF) investment was issued to target 7 space infrastructure projects that involve several industries, organisations, universities, laboratories, all around the country. Mission control and tracking facilities, robotic & automation, AI command and control, space data analysis facilities, space manufacturing capabilities, and space payload qualification facilities, are the topics under study. ANSTO together with other 5 fund recipients engaged its resources in the last-mentioned project (space payload qualification facilities), with the aim to establish the National Space Qualification Network (NSQN). Particularly, the three ANSTO facilities Centre for Accelerator Science (CAS), the Australian Synchrotron and the Gamma Technology Research Irradiator (GATRI) will focus on enhancing and improving their capabilities for space radiation damage testing of electronics used in space and ensure they meet international standards in this area. Space technology can be affected by cosmic radiation when Single Event Upset (SEU) occurs, knocking out temporary or permanently the instrumentation that is paramount for the successful accomplishment of a mission, a test, or simply the usual functionality of a service. We need to deep understand the cause and the frequency of these events, in order to reduce the risk of component failure and to consequently optimizse the electronics. Tests must be performed in ground-based facilities before commercialization of any device. ANSTO facilities use accelerators to perform radiation tests with different beams (gamma-rays, x-rays, protons and heavy ions) to eventually provide international standards of Total Ionisation Dosage (TID) radiation testing for products that can enter faster into global supply chains. Because of the limitations encountered while performing tests in vacuum, at the CAS facility, the High Energy Heavy Ion Microprobe (HIM) of the 10MV ANTARES accelerator has recently been upgraded to an external chamber for testing standard electronic chips in an ambient-in-air environment. Advantages of an ex-vacuum microprobe are: ease of handling the sample with no limits to the dimension of the sample itself, no charge effects, more effective target heat dissipation, sampling is not required, gain in terms of time used for pump-up and down the chamber, and possibility to irradiate living system without compromising them. © The Authors
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    QCM-D and neutron reflectometry study of effect of plasma treatment on cellulose-mucin interactions towards ETSA
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Siddique, A; Gresham, IJ; Davies, J; Ong, H; Traini, D; Nelson, A; Spicer, P; Prescott, SW
    Epidemic thunderstorm asthma (ETSA)[1] is associated with inhalation of airborne pollen grains and aerosolized pollen fragments, causing hypersensitive immune reactions[2] that might lead to an asthma attack. The wall of pollen grains (intine) contains cellulose which is hypothesized to initially interact with the nasal and tracheal mucous layer[3] when inhaled. The air-way mucous layer is comprised of mucin (a major glycosylated proteinaceous element) and water, which serves as a first-line-of-defence against inhaled pollen particles. Although immunological and meteorological studies have been conducted in this regard, the fundamental cause and mechanism of ETSA are under-investigated. This study is focused on unraveling inherent cellulose-mucin interactions employing quartz crystal microbalance with dissipation (QCM-D) and neutron reflectometry (NR) examining the adsorption of mucin on cellulose while mimicking a thunderstorm environment, such as the affect of plasma treatment on cellulose-mucin interactions. Here, we generate air-plasma and plasma-activated water to treat our model cellulose surfaces[4], simulating the ionized surface chemistry of thunderstorm-borne pollen particles and examine subsequent interactions. In this poster, we describe the use of QCM-D and NR to investigate cellulose-mucin interactions and the effect of plasma treatment on these biointerfacial interactions. The advanced molecular and structural data obtained from this study, coupled with immunological and meteorological investigations, will enable the mechanistic understanding, treatment, and prevention of ETSA. © The authors.