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Current trends in the application of IBA techniques to air pollution source fingerprinting and source apportionment
No full textIBA techniques have been used for many years to characterise fine particle air pollution. This is not new the techniques are well established. Typically 2-3 MeV protons are used to bombard thin filter papers and
up to four simultaneous techniques like PIXE, PIGE, RBS and ERDA will be applied to obtain (μg/g) concentrations for elements from hydrogen to lead. Generally low volume samplers are used to sample between 20-30 m3 of air over a 24 hour period, this together with IBA's sensitivity means that concentrations down to 1 ng/m3 of air sampled can be readily achieved with only a few minutes of proton irradiation. With these short irradiation times and low sensitivities for a broad range of elements in the periodic table, large numbers of samples can be obtained and analysed very quickly and easily. At ANSTO we have used IBA methods to acquire a database of over 50,000 filters from 85 different sites
through Australia and Asia, each filter has been analysed for more than 21 different chemical species
Modern depositional processes in a confined bedrock setting: benches of the Shoalhaven river
No full textThe 8th International Conference on Geomorphology of the International Association of Geomorphologists (IAG/AIG) took place in Paris at the Cité des Sciences de La Villette from August 27 to 31, 2013. The main topic of this 8th Conference was "Geomorphology and Sustainability". Organized by the Groupe Français de Géomorphologie (GFG) and open to all scientists and practitioners, this Conference included 26 scientific sessions, 5 key-note lectures and one Workshop devoted to Young Geomorphologists.
YOUNG GEOMORPHOLOGISTS SESSION
Convenors: Etienne COSSART, Johnny DOUVINET & Stuart LANE
This session welcomed young scientists (PhD students, post-doctorates) who were interested in discussing new approaches and methods in geomorphology (spatial analysis, mathematical modelling, conceptual and quantitative approaches and links between them). Presentations could focus on any component of the discipline and related earth sciences (hydrology, Quaternary geology, soil sciences, etc.), and be either fundamental or applied. Preliminary results and discussions of fieldwork and methodological strategies (observation, data acquisition before modelling) were appropriate, as well as methodological developments, such as geomorphic mapping through GIS. Equally, numerical simulation approaches such as those linked to complexity theory (agent-based modelling, Cellular Automata) or physically-based methods for specific process representations have been welcomed. The participants of this session have been invited to participate to the intensive course for young geomorphologists held at the end of the conference (from September 1st to 3rd).The lower Shoalhaven River provides an opportunity to examine bench processes in a confined setting.
Stratigraphic analysis of trenches and augur holes, ground penetrating radar, Hec-RAS modelling and
geochronological techniques combine to identify that benches of multiple levels along Bull Reach are composed
of coarse material and have been extensively eroded and reworked by modern events. Kermode et al. (2012)
established the long-term polycyclical nature of the higher alluvial surfaces (up to 193 ka in age), and this is
contrasted with the youth of the lower inset alluvial surfaces, which are shown to be less than 270 years in age.
This study evaluates the relative significance of both flood regime and effects of European settlement on the
geomorphic effectiveness of high magnitude events and investigates the characteristics of bench formation in
this confined setting. It characterises the nature of depositional events and the relationship between facies at an
event scale. Using Hec-RAS modelling, events of different recurrence intervals are compared to explore the
relative impact of varying flood magnitudes. The results bring into question the theory that inundation frequencies
of these surfaces are constant, or associated with formative processes
Neutron scattering and piezoresponse force microscopy studies of several relaxor ferroelectric materials
No full textIn this thesis, two types of relaxor ferroelectric materials, Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals and doped-(Ba,Sr)TiO3 ceramics, have been investigated using neutron scattering and piezoresponse force microscopy (PFM). Neutron diffraction studies of PIN-PMN-PT single crystals reveal changes in metric symmetry as a function of temperature, electrical poling as well as mechanical stress. It is found that a uniaxial stress longitudinally applied along the [001] direction induces a metastable orthorhombic phase out of the initial pseudo-rhombohedral phase at critical stresses dependent on temperature. A comparative study between the crystals poled along [001] and [111] directions show that, in the former case, an orthorhombic phase is stable at room temperature whereas the corresponding phase in the latter is of rhombohedral symmetry. Electrical poling is also shown to enhance the long range ferroelectric order and leads to the rhombohedral to tetragonal phase transition becoming apparent in the dielectric behavior. Elastic diffuse scattering confirms the presence of polar nano-regions (PNR's) in the PIN-PMN-PT system. The PNR's start to grow in population at ~630 K and concurrently the dipole correlation lengths become larger. At 300 K, characteristic "butterfly" and ellipsoid shaped diffuse patterns are observed on the HK0 reciprocal space plane. Electrical poling along the [110] direction produces a marked asymmetry in the diffuse scattering patterns, with the perpendicular-to-the-field components suppressed. Several low energy phonon branches along the [001] and [111] directions have been measured using triple-axis neutron spectroscopy. PNR-acoustic mode coupling is confirmed for the [110] transverse acoustic phonons polarized along the [1-10] direction. This coupling is anisotropic and correlates with the distribution of the PNR's. The famous "waterfall" phenomenon is also observed on the [001] and [110] transverse optical branches. Real space PFM imaging shows a highly disordered, labyrinthine domain pattern on the (001) and (111) surfaces in contrast to the (110) surface that develops a preferential alignment along 110 directions. The formation of these domain patterns is interpreted as a modulation effect associated with the presence of the PNR's. PFM switching spectroscopy mapping on an (001) surface reveals the distribution pattern of sub-surface defect-related internal charge fields, which nonetheless is uncorrelated with the domain pattern thereof. The local polarization switching behavior is similar for the (001) and (110) surfaces but apparently different from the (111) surface possibly due to an extrinsic internal charge field effect. Doped-(Ba,Sr)TiO3 ceramics have also been studied as a model BaTiO3-based relaxor. As this material is in its ergodic paraelectric phase at room temperature, no pristine ferroelectric domains are observed in PFM. However, short-lived/fast-relaxing surface polar states can be induced by applied tip biases as a result of the polar precursor/PNR's present, and well-defined piezoresponse hysteresis loops are thus formed. The relaxation behavior of the induced polar states is related to the PNR dynamics of the system. Spatially-resolved piezoresponse relaxation mapping reveals the presence of sub-micron correlation features due to the chemical inhomogeneity of the A-site Ba/Sr elements, as evidenced by a site-correlated elemental mapping microanalysis.© The Australian University, 2014
Removal of aluminium from aqueous solutions using PAN-based adsorbents: characterisation, kinetics, equilibrium and thermodynamic studies
No full textEconomic adsorbents in bead form were fabricated and utilised for the adsorption of Al(3+) from aqueous solutions. Polyacrylonitrile (PAN) beads, PAN powder and the thermally treated PAN beads (250 °C/48 h/Ar and 600 °C/48 h/Ar-H2) were characterised using different techniques including Fourier transform infrared spectroscopy, X-ray diffraction, specific surface analysis (Brunauer-Emmett-Teller), thermogravimetric analysis as well as scanning electron microscopy. Effects of pH, contact time, kinetics and adsorption isotherms at different temperatures were investigated in batch mode experiments. Aluminium kinetic data best fit the Lagergren pseudo-second-order adsorption model indicating a one-step, surface-only, adsorption process with chemisorption being the rate limiting step. Equilibrium adsorption data followed a Langmuir adsorption model with fairly low monolayer adsorption capacities suitable for freshwater clean-up only. Various constants including thermodynamic constants were evaluated from the experimental results obtained at 20, 40 and 60 °C. Positive values of ΔH° indicated that the adsorption of Al(3+) onto all three adsorbents was endothermic with less energy input required for PAN powder compared to PAN beads and low-temperature thermally treated PAN. Negative ΔG° values indicated that the aluminium adsorption process was spontaneous for all adsorbents examined. © 2020 Springer Natur
SNARE-ing the structures of Sec1/Munc18 proteins
No full textMembrane fusion is essential for cellular transport in eukaryotes. Abnormalities contribute to a wide range of diseases including diabetes and neurological disorders. A key regulator of SNARE-mediated membrane fusion is the Sec1/Munc18 (SM) protein family. Universal structural features of SM proteins have been identified that affect the way these interact with their partner Syntaxin SNARE proteins. Whilst the molecular basis for SM-regulated SNARE complex formation has been extensively studied, it remains poorly understood. Recent crystal structures of SM proteins alone or in complex have provided new insight. Here we examine the available structural information on SM proteins for clues to how these enigmatic proteins might regulate SNARE complex assembly and membrane fusion. © 2014, Elsevier Ltd
Little Forest legacy site - summary of site history until the commencement of waste disposal in 1960
Get PDFThe Australian Atomic Energy Commission (AAEC) disposed of low-level radioactive waste at a site in the Little Forest area on the southern periphery of Sydney between 1960 and 1968. Following common practice of the period, a clay-rich site was selected in the vicinity of the AAEC’s facility at Lucas Heights, and waste was mainly disposed by burial in closely spaced unlined trenches. During the time of operations (and subsequently until 2014), the site was known as the ‘Little Forest Burial Ground’ (LFBG).
In recent years, ANSTO has been implementing a detailed scientific study of the status of the disposal site, now referred to as the Little Forest Legacy Site (LFLS). This study includes sampling of vegetation, groundwater and soils. As part of the research, documents related to the disposal operations have been reviewed, as well as information and data from over 40 years of monitoring and studies of the LFLS. During these investigations, it has become clear that although numerous records have been preserved, there are nevertheless some key information gaps. Furthermore, while there is evidence of several previous attempts to summarise the material, none of these has led to a definitive summary of the history of the site and disposal activities.
The present report aims to summarise the history of the site until the commencement of disposal operations in 1960. This document contains information on the technical justification and other factors involved in the selection of the site, and some comments on the site selection process are presented in the final section. The main objective of this report is to provide a record of the events during this period, which will assist in understanding the disposal operations at the site and provide a context for interpreting subsequent monitoring data
Seismic origin of the Atacama Desert boulder fields
No full textExtensive fields of large boulders are common around the base of hills in the Atacama Desert. How these boulders are transported from nearby hillslopes is unclear given the lack of rainfall of the region. Here we document the central role of seismicity, not runoff, in transporting and smoothing >1 ton boulders all across the hyperarid core of the Atacama Desert. The generally granitoid boulders emerge as corestones on hillslopes at an erosion rate of 0.1-1 m Ma(-1). Thereafter, physical and cosmogenic isotopic evidence suggests that boulders slide and bounce rather than roll down hills and onto adjacent flats. In the transport process, the largest boulders are split and the smaller ones are weathered to grus, narrowing average boulder mass to similar to 2 tons (12 Ma, making them among the oldest continuously exposed features on the Earth. Boulder rubbing is just one geologic feature among many in the Atacama that underscore the role that seismicity probably plays in shaping landscapes of the waterless worlds of the solar system. © 2015, Elsevier B.V
Effect of landscape fires on the demography of the endangered New Caledonian conifer Callitris sulcata
No full textNew Caledonia is a global biodiversity hotspot and an epicentre for Gondwanan conifers, many of which are
threatened by mining and by altered fire regimes. We studied the distribution, abundance and demography of
the endangered Callitris sulcata. The largest populations are restricted to one river system in the south-east of
the island, with satellite populations in adjoining rivers. The local distribution is controlled by the fire protection
afforded by terrain features such as scree slopes, creeklines and small cliffs. Adult trees, which have comparatively
thick bark, are able to tolerate and recover from infrequent surface fires, but severe fires kill trees and the seeds
they store, a pattern similar to that in many Australian Callitris species. Radiocarbon dating revealed the species
is slower growing than Australian Callitris species, possibly due to the extreme infertility of the ultramafic soils.
The species is of high cultural value to the indigenous population who also prizes the durable and aromatic timber,
and harvests have been traditionally regulated. Illegal cutting of trees has become a problem, but uncontrolled
fires, which have caused substantial population declines, dwarf this threat. Given these threats, conservation of
the species hinges on ensuring some populations remain remote and rarely visited by humans. © 2015, Elsevier Ltd
Physics at the Australian Nuclear Science and Technology Organisation
No full textThe Australian Nuclear Science and Technology Organisation is Australia’s nuclear national laboratory and is the prime repository of nuclear expertise in the country.
It plays a key role in research, operation of major facilities,isotope production and advice to Government. It was founded in 1987, as the successor to the Australian
Atomic Energy Commission, which had existed from 1952. For almost 50 years, from 1958 until 2006, the AAEC and ANSTO operated the HIFAR heavy-water reactor, the second research reactor to be established in Asia, the first after India. Initially the AAEC’s focus was on nuclear power and nuclear fuel cycle issues, but in the ANSTO era, the focus has shifted towards the technological use of nuclear methods in medicine, the environment and science more generally. © 2015, Association of Asia Pacific Physical Societies
The nature of fluctuating lakes in the southern Amu-dar'ya delta
No full textThe delta region of the Amu-dar'ya has a complex history of shifting river channels that has impacted extensively
on the Aral Sea and on the areas of the delta that saw human settlement from prehistoric times onwards. This
paper explores evidence drawn from archeological, historical and environmental data relating to lakes that
formed in the south of the delta on the east bank of the river and their impact on settlement patterns in this
area, in particular the potential impact of variable flooding on the major fortified site of Akchakhan-kala. Testing
of the area around the sites showed that the site had not been flooded but was founded on riverine or lacustrine
clays. Shortly after the initial abandonment of the site, the immediate environment was covered by dune fields. © 2015, Elsevier B.V