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Mechanical behaviour and residual stress field of dissimilar laser welded joints
No full textNo abstract availabl
Post-LGM evolution of the lower Ord River, WA, constrained by luminescence and cosmogenic radionuclide dating
No full textThe landscape history of northern Australia is significant for understanding both environmental and
human history. In this region the Upper Pleistocene to Holocene represents a period of major flux in
response to external drivers such as climate variation and sea-level change. The influence of these
drivers has been profound, and they have exerted significant controls on landscape form and
composition along Australia’s northern margin. This also has implications for groundwater resources
and quality.
This study investigates the lower Ord River system, a bedrock-dominated catchment in the East
Kimberley region of northwest Western Australia. Geochronological and geomorphological
investigations of landforms of the lower Ord plain, and its paleo-floodplain within the central Ord
River valley, highlight the significance of the terminal stages of the Last Glacial Maximum (LGM) as a
control on regional base level and consequently on landscape change.
The timing of capture of the Ord River from its northeast-draining paleo-valley to its present
westerly course is constrained by cosmogenic radionuclide bedrock exposure ages from Tarrara Bar -
the likely location of capture by westward flowing drainage at ca. 15 ka. Optically-stimulated
luminescence ages from scroll plains on the lower Ord River downstream of Tarrara Bar are younger
than 7 ka, suggesting that their evolution is tied to regional climatic variation affecting sediment
supply to these lower reaches of the system post-LGM sea-level stabilisation.
This landscape history is significant in that it controls the distribution and nature of alluvial materials
within both the current and paleo-valley systems, and has implications for the properties of
depositional units that may influence the distribution and quality of groundwater. © Author(s
Structural Characterization of Olivine Li (Mg0.5Ni0.5) PO4 by TEM
No full textThe structural characteristics of olivine-type lithium orthophosphate Li(Mg0.5Ni0.5)PO4 synthesized via solid-state reaction have been studied using X-ray diffraction, ion beam technique, scanning electron microscopy, infrared spectroscopy, transmission electron microscopy and energy dispersive X-ray analysis. The parent LiNiPO4 compound can be synthesized in olivine structure without any evidence of secondary phases as impurities. The structural quality of the parent LiNiPO4 in the absence of secondary component phases resulted in the formation of hexagonal closed packed structure. The olivine analogue compound containing mixed M (M = Mg, Ni) cations, Li(Mg0.5Ni0.5)PO4 contained Li3PO4 as a second phase upon synthesis, however a carbothermal reduction method produced a single-phase compound. The redox behaviour of carbon-coated Li(Mg0.5Ni0.5)PO4 cathode in aqueous lithium hydroxide as the electrolyte showed reversible lithium intercalation. © 2020 Springer Nature Switzerland AG
Italian - Australian archaeology and cultureal heritage workshop, "new scientific techniques in archaeology, paleo-anthropology and cultural heritage".
Full text linkThis workshop is promoting exchange and collaboration amongst Italian, Australian and international experts from across the spectrum of the natural sciences and the humanities. Focus on the impact of recent analytical technological developments in applications to pre-history, human dispersal across the globe, paleo-anthropology and archaeology.
The workshop will deal with a variety of interdisciplinary areas, in particular the latest scientific tools in radiometric dating, molecular and isotopic analyses, and spectroscopic and structural studies using advanced radiation techniques operating at unprecedented levels of sensitivity and accuracy. These nuclear-based techniques can provide isotopic characterisation of biological, organic and terrestrial samples of most types; provide chemical, spatial and temporal information of objects leading to identification and mapping of the climate, geology, and anthropological environment; as well as perform non-invasive studies of irreplaceable works of art. © ANST
Shedding light on the past
No full textThe Amuq valley or plain of Antioch, located in the Hatay province of south
central Turkey, has been densely inhabited by humans for some 9,000 years.
The plain provides a fruitful ground for archaeological study due to the abnormally
large number of preserved ancient sites found there. Surrounded by mountains
on all sides and fed by three rivers, the fertile valley provides an opportunity to
study the relationship of ancient man and his environment in microcosm.
The floor of the valley has been the home of several lakes: some of the largest
archaeological sites existing in the mid-late Holocene appear to have been
located near-by the Lake of Antioch which evolved during this period.
A sedimentary core, representing an estimated 7,000 years of history, was taken
from the lake. Synchrotron x-ray fluorescence measurements were performed
on sections of the core. Analysis yielded the distribution of elemental masses
spanning from Ca to Mo as a function of
depth from the surface.
Figure 1 shows the results for Cu. Changes
in elemental concentration with time reflect
the changes in the local environment at the
time of deposition. Higher concentrations of
copper may reflect metal working activities:
there is a maximum in Fig. 1 around 5000
BP, a high period in settlement history.
Elemental concentrations measured follow
a number of distinct patterns that may be
related to local geomorphology and climate. In this fashion a historical account
of the development of the Lake of Antioch was constructed from the data.
The ebb and swell of the lake as well as changes in the local river courses
directly influence man’s presence in the region. Signals of such environmental
change can be discerned from tracking diachronic changes in elemental
concentrations throughout the sediment core. These elements serve as proxies
for environmental change, both human and climate induced. The data suggest that man’s activities may have aggravated some of the erosional processes. © ANST
Controlled pore structure modification of diatoms by atomic layer deposition of TiO2
No full textDiatoms produce diverse three-dimensional, regular silica structures with nanometer to micrometer dimensions and hold considerable promise for biological or biomimetic fabrication of nanostructured materials and devices. The unique hierarchical porous structure of diatom frustules is in particular attractive for membrane applications in microfluidic systems. In this paper, a procedure for pore size modifications of two centric diatom species, Coscinodiscus sp. and Thalassiosira eccentrica (T. eccentrica) using the atomic layer deposition (ALD) of ultrathin films of titanium oxide (TiO2) is described. TiO2 is deposited by sequential exposures to titanium chloride (TiCl4) and water. The modified diatom membranes were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDAX), and secondary ion mass spectrometry (SIMS). These techniques confirmed the controlled reduction of pore sizes while preserving the shape of the diatom membrane pores. Pore diameters of diatom membranes can be further tailored for specific applications by varying the number of cycles and by changing their surface functionality.© The Royal Society of Chemistry 200
Gold Nanoparticle Incorporation into Porous Titania Networks Using an Agarose Gel Templating Technique for Photocatalytic Applications
No full textPorous titania networks containing gold nanoparticles have been synthesized and tested in photocatalytic applications. The porous structure was controlled using a templating technique, while a range of gold concentrations and a variety of routes were investigated to incorporate the gold nanoparticles. The influence of these parameters on the final structure (surface area and pore size), the gold crystal size, distribution, and content, and the photocatalytic activity of the porous materials were investigated. UV−vis diffuse reflectance spectra of the Au/TiO2 materials showed strong absorbance at approximately 580 nm, indicating the successful incorporation of the gold species. X-ray diffraction analysis ascertained that the titania materials were crystalline (anatase phase) with gold peaks observed only when the gold content was greater than 0.25 wt %. Gold distribution and content in the materials were measured using secondary ion mass spectrometry and inductively coupled plasma mass spectrometry. From transmission electron microscopy analysis, the gold particle size and distribution varied with both the material preparation method and the concentration of gold used in the synthesis. Photocatalytic activity was dependent on the gold particle size and gold quantity. The highest photocatalytic activity under UV light irradiation as monitored by the photodecomposition of methylene blue was obtained for the Au/TiO2 sample containing 2.0 wt % gold prepared by the deposition of gold onto prefabricated porous TiO2.© 2008 American Chemical Societ
Toward sustainable energy: photocatalysis of Cr-doped TiO2: 2. effect of defect disorder
No full textThe present chain of five papers considers the concept of solar-to-chemical energy conversion using TiO2-based semiconductors. The series reports the effect of chromium on the key performance-related properties of polycrystalline TiO2 (rutile), including electronic structure, photocatalytic activity, intrinsic defect disorder, electrochemical coupling and surface versus bulk properties. In this work, we show that the effect of chromium on photocatalytic performance of TiO2 depends on its elemental content and the related defect disorder that is determined by oxygen activity in the oxide lattice. At high oxygen activity, chromium leads to enhanced photocatalytic performance only for dilute solid solutions (up to 0.04–0.043 at.% Cr). Higher chromium content results in a decrease of photocatalytic activity below that for pure TiO2, despite the observed substantial decrease of the band gap. The photocatalytic performance of Cr-doped TiO2 annealed in reducing conditions is low within the entire studied range of compositions. The obtained results led to derivation of a theoretical model representing the mechanism of the light-induced reactivity of TiO2 with water and the related charge transfer. The photocatalytic performance is considered in terms of a competitive effect of several key performance-related properties. The performance is predominantly influenced by the concentration of titanium vacancies acting as reactive surface sites related to anodic charge transfer. © 2018 Springer Natur
NEMA NU 4-2008 validation and applications of the PET-SORTEO Monte Carlo simulations platform for the geometry of the Inveon PET preclinical scanner
No full textMonte Carlo-based simulation of positron emission tomography (PET) data plays a key role in the design and optimization of data correction and processing methods. Our first aim was to adapt and configure the PET-SORTEO Monte Carlo simulation program for the geometry of the widely distributed Inveon PET preclinical scanner manufactured by Siemens Preclinical Solutions. The validation was carried out against actual measurements performed on the Inveon PET scanner at the Australian Nuclear Science and Technology Organisation in Australia and at the Brain and Mind Research Institute and by strictly following the NEMA NU 4-2008 standard. The comparison of simulated and experimental performance measurements included spatial resolution, sensitivity, scatter fraction and count rates, image quality and Derenzo phantom studies. Results showed that PET-SORTEO reliably reproduces the performances of this Inveon preclinical system. In addition, imaging studies showed that the PET-SORTEO simulation program provides raw data for the Inveon scanner that can be fully corrected and reconstructed using the same programs as for the actual data. All correction techniques (attenuation, scatter, randoms, dead-time, and normalization) can be applied on the simulated data leading to fully quantitative reconstructed images. In the second part of the study, we demonstrated its ability to generate fast and realistic biological studies. PET-SORTEO is a workable and reliable tool that can be used, in a classical way, to validate and/or optimize a single PET data processing step such as a reconstruction method. However, we demonstrated that by combining a realistic simulated biological study ([11C]Raclopride here) involving different condition groups, simulation allows one also to assess and optimize the data correction, reconstruction and data processing line flow as a whole, specifically for each biological study, which is our ultimate intent.
© 2017 IOP Publishin