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In situ neutron powder diffraction using custom-made lithium-ion batteries
No full textLi-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric vehicles.1,2 However, many challenges, such as energy density and battery lifetimes, need to be overcome before this particular battery technology can be widely implemented in such applications.3 This research is challenging, and we outline a method to address these challenges using in situ NPD to probe the crystal structure of electrodes undergoing electrochemical cycling (charge/discharge) in a battery. NPD data help determine the underlying structural mechanism responsible for a range of electrode properties, and this information can direct the development of better electrodes and batteries.
We briefly review six types of battery designs custom-made for NPD experiments and detail the method to construct the ‘roll-over’ cell that we have successfully used on the high-intensity NPD instrument, WOMBAT, at the Australian Nuclear Science and Technology Organisation (ANSTO). The design considerations and materials used for cell construction are discussed in conjunction with aspects of the actual in situ NPD experiment and initial directions are presented on how to analyze such complex in situ data
In situ observation and neutron diffraction of NiTi powder sintering
No full textThis study investigated NiTi powder sintering behaviour from elemental powder mixtures of Ni/Ti and Ni/TiH2 using in situ neutron diffraction and in situ scanning electron microscopy. The sintered porous alloys have open porosities ranging from 2.7% to 36.0%. In comparison to the Ni/Ti compact, dehydrogenation occurring in the Ni/TiH2 compact leads to less densification yet higher chemical homogenization only after high-temperature sintering. For the first time, direct evidence of the eutectoid phase transformation of NiTi at 620 °C is reported by in situ neutron diffraction. A comparative study of cyclic stress–strain behaviours of the porous NiTi alloys made from Ni/Ti and Ni/TiH2 compacts indicate that the samples sintered from the Ni/TiH2 compact exhibited a much higher porosity, larger pore size, lower fracture strength, lower close-to-overall porosity ratio and lower Young’s modulus. Instead of enhanced densification by the use of TiH2 as reported in the literature, this study shows an adverse effect of TiH2 on powder densification in NiTi.© 2013 Acta Materialia Inc
Comparison of proton and helium induced M subshell X-ray production cross sections with the ECUSAR theory
No full textM subshell X-ray production cross sections have been measured for Mα12, Mβ1, Mγ, M2–N4 and M1–O23 transitions representing all five M subshells. These experimental cross sections have been compared with the ECUSAR theory of Lapicki and four parameter fits are given to the experiment to theory ratios covering the proton and helium ion energy range from 0.5 to 3 MeV on thin W, Au, Pb, Th and U targets.© 2013 Elsevier B.V
Solid phases responsible for MnII, CrIII, CoII, Ni, CuII and Zn immobilization by a modified bauxite refinery residue (red mud) at pH 7.5
No full textAlthough modified bauxite refinery residues (MBRR) immobilize trace metals, the retention mechanisms in this complex multiphase material have not been examined in detail. In this study, X-ray absorption spectroscopy was used to investigate the host minerals, and retention mechanisms, responsible for binding MnII, CrIII, CoII, Ni, Cu and Zn in MBRR. High metal loadings (∼10 mM at pH 3) in aqueous phases simulated highly contaminated mine drainage environments, whereas a final pH of 7.5 represents the typical MBRR pH buffering providing surface loadings of 1.7–2.6 wt%. Under these conditions, CrIII precipitated as a solid phase similar to γ-CrOOH and/or amorphous Cr(OH)3, regardless of host mineral, whereas MnII immobilization was associated with (partial) oxidation in all cases. Cobalt and Ni precipitated primarily as hydrotalcite-like solids when in contact with the MBRR, and sodalite, gibbsite and hydrotalcite tended to dominate this process. Cu uptake by MBRR resulted from the precipitation of Cu(OH)2 although sorption processes may have made an additional contribution, whereas Zn precipitated as a solid phase similar to that of hydrozincite. The nature of the trace metal precipitate formed was often influenced by the host mineral constituent of MBRR, indicating that specific minerals in the MBRR can be primarily responsible for its metal immobilization properties, with gibbsite, hematite and hydrotalcite featuring prominently. © 2013 Elsevier B.V
Industrial past, urban future: using palaeo-studies to determine the industrial legacy of the Barwon Estuary, Victoria, Australia.
No full textAround the globe, heavy industry has often been associated with estuaries, which provide water for operations, waste disposal and navigation. Many of these practices leave a legacy of contamination, which accumulate in the estuaries, which act as sediment sinks. Heavy metal contaminants may remain buried, even after the industrial practices are ceased. The Connewarre Complex is a series of wetlands, within the Port Philip and Bellarine Ramsar site. Through a unique combination of techniques, including diatom assemblages, biogeochemistry (δ13C, δ15N, C/N) and heavy metal content, the major anthropogenic influences over the last 170 years and the biotic response has been determined. Key features that can be elucidated include regulation of the waterways, establishment of heavy industry and major shifts in climatic conditions. In combination, these drivers have acted to rapidly shift the condition of the wetland from early in settlement such that the perceived ‘natural ecological character’ is actually an artificial one. The legacy of contamination is common to many Ramsar-listed wetlands. The lesson from this site is that, when making plans to manage the ecological condition of a wetland, past use needs to be considered to ensure that well meaning interventions do not exacerbate risk of mobilising contaminants best left undisturbed
Investigation of the vibrational properties of cubic yttria-stabilized zirconia: A combined experimental and theoretical study
No full textA combined experimental and theoretical investigation into the vibrational properties of cubic 8–9 mol% yttria-stabilized zirconia (YSZ) is presented. Measurements of acoustic phonon dispersion curves have been obtained from inelastic neutron scattering investigations using a triple axis spectrometer, as well as calculations of the vibrational density-of-states (vDOS) using density-functional theory. The present measurements agree closely with, and extend, previously published results. The phonons become broader and decrease in intensity as the Brillouin zone boundary is approached, particularly in the Γ–Δ–X direction. Interestingly, there is evidence of a previously unreported low energy phonon band (8–9 meV) in the Γ–Σ–X direction, which could possibly be related to the stabilization (by yttria doping) of the imaginary mode of cubic ZrO2 about the X-point. Compared to pure cubic ZrO2, the vDOS of YSZ are broader and extend to higher frequency. Furthermore, the prominent Zr-related feature in the vDOS of c-ZrO2 at ≈14 meV is shifted to higher energy in the vDOS of YSZ. This behavior is consistent with the measured dispersion bands (first acoustic branch in the Γ–X direction, about the X-point) of YSZ which is higher in energy by a similar amount relative to that of c-ZrO2, thus providing support for the structural model considered
Comparing trace metal bioaccumulation characteristics of three freshwater decapods of the genus Macrobrachium
No full textPotential sources and kinetics of metal bioaccumulation by the three Macrobrachium prawn species M. australiense, M. rosenbergii and M. latidactylus were assessed in laboratory experiments. The prawns were exposed to two scenarios: cadmium in water only; and exposure to metal-rich mine tailings in the same water. The cadmium accumulation from the dissolved exposure during 7 days, followed by depuration in cadmium-free water for 7 days, was compared with predictions from a biokinetic model that had previously been developed for M. australiense. M. australiense and M. latidactylus accumulated significant tissue cadmium during the exposure phase, albeit with different uptake rates. All three species retained >95% of the bioaccumulated cadmium during the depuration phase, indicating very slow efflux rates. Following exposure to tailings, there were significant (p < 0.05) differences in tissue arsenic, cadmium, lead and zinc concentrations among species. Cadmium and zinc concentrations were increased relative to controls for all three species but were not different between treatments (direct/indirect contact with tailings), suggesting these metals were primarily accumulated via the dissolved phase. All species bioaccumulated significantly greater arsenic and lead when in direct contact with mine tailings, demonstrating the importance of an ingestion pathway for these metals. Copper was not bioaccumulated above control concentrations for any species. The differences between the metal accumulation of the three prawns indicated that a biokinetic model of cadmium bioaccumulation for M. australiense could potentially be used to describe the metal bioaccumulation of the other two prawn species, albeit with an over-prediction of 3–9 times. Despite these being the same genus of decapod crustacean, the study highlights the issues with using surrogate species, even under controlled laboratory conditions. It is recommended that future studies using surrogate species quantify the metal bioaccumulation characteristics of each species in order to account for any differences between species.© 2014, Elsevier B.V
Use of coal in the Bronze Age in China
No full textPeople in northern and western China were probably the first in the world to use coal as a source of energy in a consistent way. The ages cluster around 1900–2200 BC in modern day Inner Mongolia and Shanxi provinces. These are areas where near-surface coal is abundant today and woody vegetation was scant in the Bronze Age. Since coal is bulky to transport, it was probably not a cost-effective energy source in areas with abundant wood supply. The sites where coal was first used were probably occupied for a century to a few centuries at most and were associated with Bronze Age societies. The earliest age is about 3490 BC from a house site at Xiahe in Shaanxi Province; however, the coal is not securely tied to the radiocarbon ages and is assumed to have been used at this site sometime after 3490 BC. The elemental composition of modern mine and sedimentary coal in nearby archaeological contexts suggests that coal was used from local sources, and that elemental composition of coal may be a useful tool in identifying site origin of coal
Three-dimensional characterization of the permeability of W–Cu composites using a new “TriBeam” technique
No full textLarge three-dimensional microstructural datasets have been gathered for two W–Cu composites of 10 and 15 wt.% Cu using the TriBeam system via in situ femtosecond laser sectioning in a scanning electron microscope. Laser ablation was performed on W–Cu samples along a 90 ° edge, milling parallel with the imaging surface. Secondary electron images for 1000 two-dimensional slices were segmented into binary images representing Cu and W components using EM/MPM (expectation–maximization/maximization of the posterior marginals) image-processing algorithms. A statistically random volume sampling approach has been employed to evaluate the microstructural and property volume element sizes necessary for the assessment of volume fraction, surface-area to volume ratio and permeability, respectively. This approach also characterizes the mean values and variability in microstructure and properties for volume elements ranging from 10 μm to 160 μm on edge. The converged values of the volume fractions of Cu closely match experimental values measured by the Archimedes technique.© 2013 Acta Materialia Inc
Dose enhancement effects to the nucleus and mitochondria from gold nanoparticles in the cytosol
No full textGold nanoparticles (GNPs) have shown potential as dose enhancers for radiation therapy. Since damage to the genome affects the viability of a cell, it is generally assumed that GNPs have to localise within the cell nucleus. In practice, however, GNPs tend to localise in the cytoplasm yet still appear to have a dose enhancing effect on the cell. Whether this effect can be attributed to stress-induced biological mechanisms or to physical damage to extra-nuclear cellular targets is still unclear. There is however growing evidence to suggest that the cellular response to radiation can also be influenced by indirect processes induced when the nucleus is not directly targeted by radiation. The mitochondrion in particular may be an effective extra-nuclear radiation target given its many important functional roles in the cell. To more accurately predict the physical effect of radiation within different cell organelles, we measured the full chemical composition of a whole human lymphocytic JURKAT cell as well as two separate organelles; the cell nucleus and the mitochondrion. The experimental measurements found that all three biological materials had similar ionisation energies ~70 eV, substantially lower than that of liquid water ~78 eV. Monte Carlo simulations for 10–50 keV incident photons showed higher energy deposition and ionisation numbers in the cell and organelle materials compared to liquid water. Adding a 1% mass fraction of gold to each material increased the energy deposition by a factor of ~1.8 when averaged over all incident photon energies. Simulations of a realistic compartmentalised cell show that the presence of gold in the cytosol increases the energy deposition in the mitochondrial volume more than within the nuclear volume. We find this is due to sub-micron delocalisation of energy by photoelectrons, making the mitochondria a potentially viable indirect radiation target for GNPs that localise to the cytosol. © 2016 Institute of Physics and Engineering in Medicin