Browsing by Author "Banos, C"

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    Apparent polyploidization after gamma irradiation: pitfalls in the use of quantitative polymerase chain reaction (qPCR) for the estimation of mitochondrial and nuclear DNA gene copy numbers
    (MDPI AG, 2013-06-01) Kam, WWY; Lake, V; Banos, C; Davies, JB; Banati, RB
    Quantitative polymerase chain reaction (qPCR) has been widely used to quantify changes in gene copy numbers after radiation exposure. Here, we show that gamma irradiation ranging from 10 to 100 Gy of cells and cell-free DNA samples significantly affects the measured qPCR yield, due to radiation-induced fragmentation of the DNA template and, therefore, introduces errors into the estimation of gene copy numbers. The radiation-induced DNA fragmentation and, thus, measured qPCR yield varies with temperature not only in living cells, but also in isolated DNA irradiated under cell-free conditions. In summary, the variability in measured qPCR yield from irradiated samples introduces a significant error into the estimation of both mitochondrial and nuclear gene copy numbers and may give spurious evidence for polyploidization.© 2013, MDPI Publishing
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    Bioterrorism: the effects of biological decontamination on the recovery of electronic evidence
    (Elsevier Ltd, 2011-06-15) Hoile, R; Banos, C; Colella, M; Roux, C
    The investigation of a bioterrorism event will ultimately lead to the collection of vital data from electronic devices such as computers and mobile phones. This project sought to determine the use of gamma irradiation and formaldehyde gas as effective biological decontaminants, and the effect of these methods on the recovery of electronic evidence. Electronic items were contaminated with viable spores and then exposed to both decontaminants. Log values for each matrix were calculated with flash drives recording the highest value of 566 Gy for gamma irradiation and a maximum of 50 min exposure to formaldehyde saw the effective destruction of spores. The results indicate that recovery of data varied based on the decontaminant selected, formaldehyde gas giving the most promising results, with electronic data recovered after the required exposure time. Gamma irradiation proved damaging to electronic circuitry at levels required to render the items safe. The implications to computer intelligence and forensics will be discussed based on the outcomes of these findings. © 2011, Elsevier Ltd.
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    Evaluating irradiation dose for sterility induction and quality control of mass-produced fruit fly cactrocera tryoni (Diptera: Tephritidae)
    (Oxford University Press, 2014-06-01) Dominiak, BC; Sundaralingam, S; Jiang, L; Fanson, BG; Collins, SR; Banos, C; Davies, JB; Taylor, PW
    The sterile insect technique has been routinely used to eradicate fruit fly Bactrocera tryoni (Froggatt) incursions. This study considers whether fly quality in a mass-rearing facility can be improved by reducing irradiation doses, without sacrificing reproductive sterility. Pupae were exposed to one of five target irradiation dose ranges: 0, 40–45, 50–55, 60–65, and 70–75 Gy. Pupae were then assessed using routine quality control measures: flight ability, sex ratio, longevity under nutritional stress, emergence, and reproductive sterility. Irradiation did not have a significant effect on flight ability or sex ratio tests. Longevity under nutritional stress was significantly increased at 70–75 Gy, but no other doses differed from 0 Gy. Emergence was slightly reduced in the 50–55, 60–65, and 70–75 Gy treatments, but 40–45 Gy treatments did not differ from 0 Gy, though confounding temporal factors complicate interpretation. Reproductive sterility remained acceptable (>99.5%) for all doses— 40–45 Gy (99.78%), 50–55 Gy (100%), 60–65 Gy (100%), and 70–75 Gy (99.99%). We recommend that B. tryoni used in sterile insect technique releases be irradiated at a target dose of 50–55 Gy, providing improved quality and undiminished sterility in comparison with the current 70–75 Gy standard while also providing a substantial buffer against risk of under dosing. © 2014, Oxford University Press
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    Gamma irradiation as a biological decontaminant and its effect on common fingermark detection techniques and DNA profiling.
    (Wiley-Blackwell, 2010-01) Hoile, R; Banos, C; Colella, M; Walsh, SJ; Roux, C
    The use of disease-causing organisms and their toxins against the civilian population has defined bioterrorism and opened forensic science up to the challenges of processing contaminated evidence. This study sought to determine the use of gamma irradiation as an effective biological decontaminant and its effect on the recovery of latent fingermarks from both porous and nonporous items. Test items were contaminated with viable spores marked with latent prints and then decontaminated using a cobalt 60 gamma irradiator. Fingermark detection was the focus with standard methods including 1,2-indanedione, ninhydrin, diazafluoren-9-one, and physical developer used during this study. DNA recovery using 20% Chelex extraction and quantitative real-time polymerase chain reaction was also explored. Gamma irradiation proved effective as a bacterial decontaminant with D-values ranging from 458 to 500 Gy for nonporous items and 797–808 Gy for porous ones. The results demonstrated the successful recovery of latent marks and DNA establishing gamma irradiation as a viable decontamination option. © 2010, Wiley-Blackwell.
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    Gamma irradiation response in photonic crystal and standard optical fiber Bragg grating sensors for radiation dosimetry
    (Society of Photo-Optical Instrumentation Engineers, 2019-12-30) Baccini, D; Hinckley, S; Canning, J; Allwood, G; Cook, K; Wild, G; Davies, JB; Banos, C
    In this paper, we report the response of Cobalt-60 gamma irradiation on Photonic Crystal Fibre Bragg gratings (PCFFBGs) and standard commercial FBGs (STD-FBGs). Optical measurements were performed to determine the shift of the Bragg wavelength as a function of accumulated dose and relaxation time. To simulate real time conditions of a radiation dosimeter, the FBGs are examined through three consecutive radiation stages followed by very limited recovery times. We were able to obtain a Bragg wavelength shift with both sets of FBGs. The PCF-FBGs response included strong recovery after each irradiation compared to the STD-FBGs. This makes the PCF-FBGs strong candidates as optical fibre FBG sensors in the area of radiation dosimetry. © (2019) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).
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    Low dose gamma irradiation does not affect the quality or total ascorbic acid concentration of “sweetheart” passionfruit (passiflora edulis)
    (MDPI, 2015-08-26) Golding, JB; Blades, BL; Satyan, S; Spohr, LJ; Harris, AM; Jessup, AJ; Archer, JA; Davies, JB; Banos, C
    Passionfruit (Passiflora edulis, Sims, cultivar “Sweetheart”) were subject to gamma irradiation at levels suitable for phytosanitary purposes (0, 150, 400 and 1000 Gy) then stored at 8 °C and assessed for fruit quality and total ascorbic acid concentration after one and fourteen days. Irradiation at any dose (≤1000 Gy) did not affect passionfruit quality (overall fruit quality, colour, firmness, fruit shrivel, stem condition, weight loss, total soluble solids level (TSS), titratable acidity (TA) level, TSS/TA ratio, juice pH and rot development), nor the total ascorbic acid concentration. The length of time in storage affected some fruit quality parameters and total ascorbic acid concentration, with longer storage periods resulting in lower quality fruit and lower total ascorbic acid concentration, irrespective of irradiation. There was no interaction between irradiation treatment and storage time, indicating that irradiation did not influence the effect of storage on passionfruit quality. The results showed that the application of 150, 400 and 1000 Gy gamma irradiation to “Sweetheart” purple passionfruit did not produce any deleterious effects on fruit quality or total ascorbic acid concentration during cold storage, thus supporting the use of low dose irradiation as a phytosanitary treatment against quarantine pests in purple passionfruit. © 2015 MDPI.
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    Low dose gamma irradiation does not affect the quality, proximate or nutritional profile of ‘Brigitta’ blueberry and ‘Maravilla’ raspberry fruit
    (Elsevier, 2014-10) Golding, JB; Blades, BL; Satyan, S; Jessup, AJ; Spohr, LJ; Harris, AM; Banos, C; Davies, JB
    Blueberry (Northern Highbush, cv ‘Brigitta’) and raspberry (cv ‘Maravilla’) fruit were subject to low dose gamma irradiation (0, 150, 400 and 1000 Gy) and stored at 0 °C for three or ten days (blueberry) and two or seven days (raspberry) to determine the effects of irradiation on fruit quality and nutritional and proximate contents. In general, none of the irradiation doses (≤1000 Gy) significantly affected blueberry or raspberry fruit quality (overall fruit quality, colour, firmness, weight loss, TSS, TA levels or TSS/TA ratio), or the nutritional or proximate content (ash, carbohydrate, dietary fibre, energy, moisture, protein, sodium, potassium, total sugars, fructose, ascorbic acid, monomeric anthocyanin, citric and malic acids). The length of time in storage affected some fruit quality and nutritional and proximate content parameters (such as overall fruit quality, firmness, weight loss, TA levels, dietary fibre, potassium, ascorbic acid, citric and malic acids), with longer storage periods resulting in lower quality fruit, irrespective of irradiation treatment. No interaction was detected between the effects of irradiation treatment and storage time, indicating that the storage effect was consistent for all irradiation doses on both blueberry and raspberry fruit quality. © 2014 Elsevier B.V.
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    Predicted ionisation in mitochondria and observed acute changes in the mitochondrial transcriptome after gamma irradiation: a Monte Carlo simulation and quantitative PCR study
    (Elsevier B.V., 2013-11-01) Kam, WWY; McNamara, AL; Lake, V; Banos, C; Davies, JB; Kuncic, Z; Banati, RB
    It is a widely accepted that the cell nucleus is the primary site of radiation damage while extra-nuclear radiation effects are not yet systematically included into models of radiation damage. We performed Monte Carlo simulations assuming a spherical cell (diameter 11.5 μm) modelled after JURKAT cells with the inclusion of realistic elemental composition data based on published literature. The cell model consists of cytoplasm (density 1 g/cm3), nucleus (diameter 8.5 μm; 40% of cell volume) as well as cylindrical mitochondria (diameter 1 μm; volume 0.5 μm3) of three different densities (1, 2 and 10 g/cm3) and total mitochondrial volume relative to the cell volume (10, 20, 30%). Our simulation predicts that if mitochondria take up more than 20% of a cell's volume, ionisation events will be the preferentially located in mitochondria rather than in the cell nucleus. Using quantitative polymerase chain reaction, we substantiate in JURKAT cells that human mitochondria respond to gamma radiation with early (within 30 min) differential changes in the expression levels of 18 mitochondrially encoded genes, whereby the number of regulated genes varies in a dose-dependent but non-linear pattern (10 Gy: 1 gene; 50 Gy: 5 genes; 100 Gy: 12 genes). The simulation data as well as the experimental observations suggest that current models of acute radiation effects, which largely focus on nuclear effects, might benefit from more systematic considerations of the early mitochondrial responses and how these may subsequently determine cell response to ionising radiation. © 2013 Elsevier B.V.
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    Silver nanoparticles prepared by gamma irradiation across metal organic framework templates
    (Royal Society of Chemistry, 2015-01-07) He, L; Dumée, LF; Liu, D; Velleman, L; She, FH; Banos, C; Davies, JB; Kong, LX
    In this study, we demonstrate for the first time the successful fabrication of well-dispersed ultrafine silver nanoparticles inside metal–organic frameworks through a single step gamma irradiation at room temperature. HKUST-1 crystals are soaked in silver nitrate aqueous solution and irradiated with a Cobalt 60 source across a range of irradiation doses to synthesize highly uniformly distributed silver nano-particles. The average size of the silver nanoparticles across the Ag@HKUST-1 materials is found to vary between 1.4 and 3 nm for dose exposures between 1 and 200 kGy, respectively. The Ag@HKUST-1 hybrid crystals exhibit strong surface plasmon resonance and are highly durable and efficient catalytic materials for the reduction of 4-nitrophenol to 4-aminophenol (up to 14.46 × 10−3 s−1 for 1 kGy Ag@HKUST-1). The crystals can be easily recycled for at least five successive cycles of reaction with a conversion efficiency higher than 99.9%. The gamma irradiation is demonstrated to be an effective and environmental friendly process for the synthesis of nano-particles across confined metal–organic frameworks at room temperature with potential applications in environmental science. © 2015 The Royal Society of Chemistry
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    Single step preparation of meso-porous and reduced graphene oxide by gamma-ray irradiation in gaseous phase
    (Elsevier B.V., 2014-04-01) Dumée, LF; Feng, CF; He, L; Yi, ZF; She, FS; Peng, Z; Gao, WM; Banos, C; Davies, JB; Huynh, C; Hawkins, S; Duke, MC; Gray, S; Hodgson, PD; Kong, LX
    A facile and highly efficient route to produce simultaneously porous and reduced graphene oxide by gamma ray irradiation in hydrogen is here demonstrated. Narrowly distributed nano-scale pores (average size of ∼3 nm and surface density >44,900 pore μm−2) were generated across 10 μm thick graphene oxide bucky-papers at a total irradiation dose of 500 kGy. The graphene oxide sheet reduction was confirmed to occur homogeneously across the structures by Fourier transform infrared spectroscopy and Raman analysis. This one-step, catalyst-free, high penetration and through-put technique, offers great promises potential for the mass production of reduced graphene oxide from cheap graphene oxide. © 2014 Elsevier B.V.
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    Tuning the grade of graphene: gamma ray irradiation of free-standing graphene oxide films in gaseous phase
    (Elsevier V.V., 2014-12-15) Dumée, LF; Feng, CF; He, L; Allioux, FM; Yi, ZF; Gao, WM; Banos, C; Davies, JB; Kong, LX
    A direct approach to functionalize and reduce pre-shaped graphene oxide 3D architectures is demonstrated by gamma ray irradiation in gaseous phase under analytical grade air, N2 or H2. The formation of radicals upon gamma ray irradiation is shown to lead to surface functionalization of the graphene oxide sheets. The reduction degree of graphene oxide, which can be controlled through varying the γ-ray total dose irradiation, leads to the synthesis of highly crystalline and near defect-free graphene based materials. The crystalline structure of the graphene oxide and γ-ray reduced graphene oxide was investigated by x-ray diffraction and Raman spectroscopy. The results reveal no noticeable changes in the size of sp2 graphitic structures for the range of tested gases and total exposure doses suggesting that the irradiation in gaseous phase does not damage the graphene crystalline domains. As confirmed by X-ray photoemission spectroscopy, the C/O ratio of γ-ray reduced graphene oxide is increasing from 2.37 for graphene oxide to 6.25 upon irradiation in hydrogen gas. The removal of oxygen atoms with this reduction process in hydrogen results in a sharp 400 times increase of the electrical conductivity of γ-ray reduced graphene oxide from 0.05 S cm−1 to as high as 23 S cm−1. A significant increase of the contact angle of the γ-ray reduced graphene oxide bucky-papers and weakened oxygen rich groups characteristic peaks across the Fourier transform infrared spectra further illustrate the efficacy of the γ-ray reduction process. A mechanism correlating the interaction between hydrogen radicals formed upon γ-ray irradiation of hydrogen gas and the oxygen rich groups on the surface of the graphene oxide bucky-papers is proposed, in order to contribute to the synthesis of reduced graphene materials through solution-free chemistry routes. © 2014 Elsevier B.V.