1,720,993 research outputs found
The Genyornis egg: response to Miller et al.'s commentary on Grellet-Tinner et al., 2016
No full textGerald Grellet-Tinner, Nigel A. Spooner, Warren D. Handley, Trevor H. Worth
Explosives sensing based on suspended core fiber coated with conjugated polymer
No full textSuspended core fibers with voids surrounding the core coated with conjugate polymer were used to detect nitroaromatic explosives based on the fluorescence quenching technique. The background Raman signal from a suspended core fiber was used as reference to optimize coupled into the core of the fiber. The fluorescence spectra were integrated across all wavelengths to extract the integrated fluorescence intensity at regular time intervals. Fluorescence decay lifetimes were obtained by fitting a single exponential decay and were used to detect 1,4-dinitrobenzene (DNB), a member of the nitroaromatics family of explosives, in acetone solutions at concentrations as low as 6.3 ppm.Fenghong Chu, Georgios Tsiminis, Nigel A. Spooner and Tanya M. Monr
Optically stimulated luminescence in fluoride-phosphate glass for radiation dosimetry
Get PDFOptically stimulated luminescence (OSL) was studied in undoped and rare-earth doped fluoride–phosphate glass. Following exposure to 90Sr/90Y b-radiation, the samples demonstrated strong OSL in the 350–600 nm wavelength range. Here, we explore the effects of fabrication conditions and rare-earth dopants on the OSL. We found that the OSL intensity increases linearly with radiation dosage, indicating the suitability of fluoride–phosphate glass as a dosimeter material.Christopher A. G. Kalnins, Heike Ebendorff-Heidepriem, Nigel A. Spooner and Tanya M. Monr
Sensing explosives with suspended core fibers: Identification and quantification using Raman spectroscopy
No full textThis works demonstrates the use of suspended core optical fibers as a platform for explosives detection in solution using Raman spectroscopy. This architecture combines small sampling volumes with long light-analyte interaction lengths, resulting in identification of minute quantities of explosives in solutions. In addition, the Raman signature of the solvent is used as an internal calibration standard to allow quantification of the detected molecule. Our results show detection of sub-microgram amounts of hydrogen peroxide (H2O2) in aqueous solution, a molecule difficult to detect as it lacks the nitroaromatic units, characteristic of trinitrotoluene (TNT) based explosives, which are usually targeted by traditional optical methods such as fluorescence. The same platform without any modifications can also be used to identify and quantify comparable amounts of 1,4-dinitrobenzene (DNB), a substitute molecule for TNT. These results highlight the capability of suspended-core fibers as small, cost-efficient and low-volume explosives sensors.Georgios Tsiminis, Fenghong Chu, Nigel A. Spooner and Tanya M. Monr
Evaluating Quaternary dating methods: radiocarbon, U-series, luminescence, and amino acid racemization dates of a late Pleistocene emu egg
No full textAbstract not availableJohn W. Magee, Gifford H. Miller, Nigel A. Spooner, Danielle G. Questiaux, Malcolm T. McCulloch, Peter A. Clar
OSL dating of individual quartz ‘supergrains’ from the Ancient Middle Palaeolithic site of Cuesta de la Bajada, Spain
No full textAbstract not availableLee J. Arnold, Mathieu Duval, Martina Demuro, Nigel A. Spooner, Manuel Santonja, Alfredo Pérez-Gonzále
Measuring nitroaromatic explosives using polymer-coated microstructured optical fibers
No full textOral presentation in Technical Session 3- Chemical and material sensing. Tuesday 10 December 1400–1230Fenghong Chu, Georgios Tsiminis, Catherine E. Lang, Nigel A. Spooner and Tanya M. Monr
Surface analysis and treatment of extruded fluoride phosphate glass preforms for optical fiber fabrication
Get PDFFirst published: 20 April 2016Fabrication of fluoride phosphate glass optical fibers using the extrusion method for preform fabrication has been studied using the commercial Schott N-FK51A glass. The extrusion step was found to create a surface layer of differing composition from the bulk glass material, leading to defects drawn down onto the optical fiber surface during fiber fabrication, resulting in high loss and fragile fibers. Similar phenomena have also been observed in other fluoride-based glasses. Removal of this surface layer from preforms prior to fiber drawing was shown to improve optical fiber loss from >5 dB/m to 0.5–1.0 dB/m. The removal of this surface layer is therefore necessary to produce low-loss fluoride phosphate optical fibers.Christopher A. G. Kalnins, Nigel A. Spooner, Tanya M. Monro, and Heike Ebendorff-Heideprie
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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