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Sedimentation and vegetation change through the last glacial cycle at Echo Lake, Fraser Island.
No full textEcho Lake is an ephemeral swamp perched above the groundwater table within the subtropical
dunes of Fraser Island at 100 m above sea level. A 12 metre core was extracted in 1997-1998, with
preliminary pollen analysis and dating suggesting the site preserved a palaeoenvironmental record
beginning at 2 ka and spanning most of the last glacial cycle. However, the chronology has been
problematic and sedimentation may have been interrupted or lost through drying and burning of the
surface. Radiocarbon and optically stimulated luminescence (OSL) dating suggested an age for the
base of the sedimentary sequence of at least 100 ka. Here we present a new chronology based on
OSL on lake sediments together with ITRAX-XRF proxies for palaeoenvironmental change. © Author(s
Groundwater isotopic record in southwest Australia: links to recharge variations and climatic conditions
No full textGroundwater resources are a reliable and important source of water. Considering most large
groundwater basins can contain ‘old’ groundwater where extraction exceeds groundwater recharge,
knowledge of the past conditions and timing under which groundwater was recharged is needed to
sustainably manage groundwater resources. Applying isotopic tools to groundwater contained in
regional aquifer systems can provide low-resolution information on recharge intensity, recharge
source and past climatic conditions for the region. Furthermore, an understanding of how
groundwater recharge and climate have been connected in the past can be used to inform climate
adaptation strategies for sustaining groundwater resources during climate change.
Large regional groundwater systems, contained within the Perth Basin in southwest Australia were
investigated in this study to provide information on groundwater recharge and climate over the past
35,000 years. Regional scale databases containing groundwater age and isotopic records are not
commonly developed in Australia and are generally more site specific. Therefore, this Perth Basin
database provides a unique opportunity to study and interpret a low-resolution palaeo-archive of
groundwater recharge for southwest Australia. Groundwater ages (14CDIC) and stable O isotopes of
water (δ18O) from two regional groundwater systems within the Perth Basin have been collated and
groundwater ages calculated. The trends δ18O over time in the regional groundwater data are
consistent with the groundwater flow line data supporting our hypothesis that groundwater δ18O is
a proxy for palaeo-recharge. The Southern Perth Basin groundwater isotope record is interpreted to
be a low resolution archive of recharge driven by changes in the relative intensity of past rainfall and
recharge thresholds. This long-term stable isotopic recharge record provides a greater
understanding of groundwater palaeo-recharge, as well as how recharge and climate have been
connected in the past. © Author(s
Effect of Indium Segregation on the Surface versus Bulk Chemistry for Indium-Doped TiO2
No full textThis work reports the effect of indium segregation on the surface versus bulk composition of indium (In)-doped TiO2. The studies are performed using proton-induced X-ray emission (PIXE), secondary-ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), and Rutherford backscattering spectroscopy (RBS). The results of XPS analysis indicate that annealing of In-doped TiO2 containing 0.3 atom % In at 1273 K in the gas phase of controlled oxygen activity [p(O2) = 75 kPa and 10 Pa] results in a surface enrichment of 2.95 and 2.61 atom % In, respectively. The obtained segregation data are considered in terms of the transport of indium ions from its titanium sites in the bulk phase to the surface where these ions are incorporated into interstitial sites. The effect of oxygen activity on the segregation-induced surface enrichment is considered in terms of the formation of a low-dimensional surface structure and a
sublayer, which are charged negatively. The latter is formed as a result of strong interactions between titanium vacancies and interstitial indium ions, leading to the formation of defect complexes. The data obtained in this work may be used for engineering of TiO2-based semiconductors with enhanced performance in solar energy conversion. © 2012 American Chemical Societ
Solutions of the relativistic two-body problem II quantum mechanics
No full textThis paper discusses the formulation of a quantum mechanical equivalent of the relative time classical theory proposed in Part I. The relativistic wavefunction is derived and a covariant addition theorem is put forward which allows a covariant scattering theory to be established. The free particle eigenfunctions that are given are found not to be plane waves. A covariant partial wave analysis is also given. A means is described of converting wavefunctions that yield probability densities in 4-space to ones that yield the 3-space equivalents. Bound states are considered and covariant analogues of the Coulomb potential, harmonic oscillator potential, inverse cube law of force, square well potential, and two-body fermion interactions are discussed. © CSIRO 197
Long term fine aerosols at the Cape Grim global baseline station: 1998 to 2016
Get PDFFine aerosol measurements have been undertaken at the Cape Grim global baseline station since 1992. Ion beam analysis techniques were then used to determine the elemental composition of the samples from which source fingerprints can be determined. In this study six source fingerprints were identified to contribute to the measurements of PM2.5 at Cape Grim (from 1998 to 2016); fresh sea salt (57%), secondary sulfate and nitrates (14%), smoke (13%), aged sea salt (the product of NaCl reactions with SO2; 12%), soil dust (2.4%) and industrial metals (1.5%). Back trajectory analysis showed that local Tasmanian sources of soil dust contributed to the high soil dust measurements. High measurements of secondary aerosols were recorded when air masses were arriving from the Australian mainland, in the direction of the Victorian power stations.
When air masses were arriving from the baseline sector, the maximum concentration of aged sea salt was 1.3 μg/m3, compared to overall maximum of 4.9 μg/m3. For secondary sulfates and nitrates the maximum concentrations were 2.5 and 7.5 μg/m3 from the baseline sector and overall, respectively. While measurements at Cape Grim can be affected from long range transport from mainland Australia and some local Tasmanian sources, the average concentrations of anthropogenic sources are still considerably lower than those measured at more populated areas. For example, at Lucas Heights (located south-west of the Sydney central business district, with little local sources) the average concentrations of secondary sulfates/nitrates and aged sea air were 1.4 and 1.0 μg/m3, respectively; compared to average concentrations of 0.8 and 0.6 μg/m3, at Cape Grim. The average concentrations of smoke were compatible at the two sites. The impact of primary aerosols from vehicle exhaust at Cape Grim was limited and no corresponding fingerprint was resolved.Crown Copyright © 2017 Published by Elsevier Lt
Upper Hunter Valley Particle Characterization Study 3rd Progress Report
Get PDFThe objective of the Upper Hunter Valley Particle Characterization Study is to determine the major components and sources of particulate matter (as PM2.5 – particles with a diameter of less than 2.5
micrometres) in the two main population centres in the Upper Hunter Valley, namely Singleton and Muswellbrook.
This 3rd Progress Report presents an update on the project and some quality checks of the data.© 2013 CSIR
Ion beam irradiation of ABO4 compounds with the fergusonite, monazite, scheelite, and zircon structures
No full textThe effects of irradiation on CaWO4, SrWO4, BaWO4, YVO4, LaVO4, YNbO4, and LaNbO4 were investigated on thin crystals using 1.0 MeV Kr ions at 50‐1000 K. All of the ABO4 compounds can be amorphized with calculated damage cross sections (σa = 1/Fc0) in the range of ~0.30‐1.09 × 10‐14 cm2 ion−1 at zero Kelvin. The analysis of fluence‐temperature data returned critical temperatures for amorphization (Tc) of 311 ± 1, 358 ± 90, 325 ± 19, 415 ± 17, 541 ± 6, 636 ± 26, and 1012 ± 1 K, respectively, for the compounds listed above. Compared with previous in situ irradiation of ABO4 orthophosphate samples using 0.8 MeV Kr ions, the Tc values of LaVO4 and YVO4 are higher than those of LaPO4 and YPO4 by 82 K and 124 K, respectively. The Tc values of the three scheelite structures, CaWO4, SrWO4, and BaWO4, indicate that they are the most radiation tolerant compounds under these conditions. The A‐B cation anti‐site energies, EfAB, determined by DFT range from 2.48 to 10.58 eV and are highly correlated with the A‐B cation ionic radius ratio, rA/rB, but are not correlated with Tc across the different structure types, suggesting that the formation and migration energies of Frenkel defects play a more important role in damage recovery in these compounds. We also discuss the role of cation and anion charge/iconicity as determined by DFT. ABO4 compounds with the zircon structure and B = P or V have a distinct advantage over those with B = Si as the damaged regions do not appear to be significantly affected by polymerization of (PO4)3− or (VO4)3− groups which might stabilize the amorphous fraction and ultimately lead to phase separation as observed in zircon (ZrSiO4). © 1999-2020 John Wiley & Sons, Inc
New evidence for paleotsunamis along Hecate Strait, British Columbia, Canada
No full textVirtually all of the geological evidence for historic and prehistoric tsunamis in British Columbia has been recovered from the west side of Vancouver Island during a field campaign that ended some two decades ago. In 2014, a new multi-national paleotsunami initiative was launched in British Columbia to extend the temporal and geographical record as well as enhance the resolution of the geological evidence on Vancouver Island and many smaller islands stretching through Hecate Strait as far north as Prince Rupert. Ship support by the Canadian Coast Guard provided the opportunity to access a number of remote inlets and bays in this unique region of the province. The field effort to the north focussed mainly on the seaward facing coast line of several islands and the mainland that could have been subjected to local, regional and trans-Pacific tsunamis (earthquake or landslide generated). This region is characteristically rocky in nature, provides few situations for sediment accretion and preservation, and is regularly subjected to extreme weather and sea conditions. Peat deposits and soils are generally rare, and if present, are normally thin and lack sufficient materials to reflect appreciable time. Fortunately, shovel excavations at over two dozen widely spaced localities yielded strong evidence for past tsunami inundation. Sites with evidence of past tsunamis ranged from those with a single past event to those preserving several events. Field descriptions and organic samples for C14 and Pb dating were supplemented with multiple core samples at each site. Cores up to 1 m in length were collected for laboratory studies: imagery, gamma ray absorption, magnetic susceptibility, P-Wave velocity, X-Ray fluorescence, colour photospectrometry, as well as foram and diatom analysis. The results of this work are important in managing risk associated with future tsunamis as new critical infrastructure facilities are developed and old facilities are replaced along Canada’s west coast
Synthesis and in vitro evaluation of tetrahydroisoquinolines with pendent aromatics as sigma-2 (σ2) selective ligands
No full textAbstract5-Bromo-N-[4-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)-butyl)]-2,3-dimethoxybenzamide 1 is a potent and selective σ2 receptor ligand suitable for further development. A series of new analogues, incorporating a variety of isoquinoline and carboxylic acid moieties, linked together with either a linear or cyclic amine spacer have been synthesised and assessed for their σ1/σ2 binding affinity and selectivity. Compounds with a rigid piperidine spacer gave Ki values for the σ2 receptor between 8.7–845 nM. Changing the configuration of the methoxy groups on the isoquinoline moiety resulted in molecules with σ2Ki values of 4.4–133 nM whereas varying the length and flexibility of the carbon spaces gave σ2Ki values 0.88–15.0 nM, some of the most active, selective σ2 ligands to date. Thus, the flexibility and length of the carbon linker and the carboxylic acid moiety are confirmed to be key to the exceptional binding affinity and selectivity for this active series. Additionally, the incorporation of a halogen on selected carboxylic acid moieties provided a convenient strategy for the introduction of a radiohalogen for applications in pharmacological and imaging studies. © 2014 The Royal Society of Chemistr
High ambient temperature increases intravenous methamphetamine self-administration on fixed and progressive ratio schedules in rats
No full textMethamphetamine is a drug that is often consumed at dance parties or nightclubs where the ambient temperature is high. The present study determined whether such high ambient temperatures alter intravenous methamphetamine self-administration in the rat. Male Hooded Wistar rats were trained to self-administer intravenous methamphetamine (0.1 mg/kg/infusion) under a fixed ratio 1 (FR1) or progressive ratio (PR) schedule of reinforcement at an ambient temperature of 23 +/- 1 degrees C. They were then given their daily self-administration session at a raised ambient temperature of 30 +/- 1 degrees C. Methamphetamine self-administration was increased at 30 degrees C under both FR1 and PR reinforcement schedules, with the latter effect indicating that heat enhances the motivation to obtain methamphetamine. High temperatures did not alter self-administration of the D1 receptor agonist SKF 82958 in methamphetamine-experienced rats suggesting some specificity in the methamphetamine effect. When rats were given access to drink isotonic saline solution during methamphetamine self-administration sessions they drank much more solution at 30 degrees C than 23 degrees C. However, availability of isotonic saline to drink did not alter the heat-induced facilitation of methamphetamine self-administration (PR schedule) indicating that the heat effect does not simply reflect increased motivation for intravenous fluids. Hyperthermia was evident in rats self-administering methamphetamine at high ambient temperatures and fluid consumption did not prevent this effect. Heat did not affect blood levels of methamphetamine, or its principal metabolite amphetamine indicating that the facilitatory effect of heat did not reflect altered methamphetamine pharmacokinetics. Overall, these results show that high ambient temperatures increase the reinforcing efficacy of methamphetamine and encourage higher levels of drug intake. © 2020 by British Association for Psychopharmacolog