Collisions of small ice particles under microgravity conditions (II): Does the chemical composition of the ice change the collisional properties?

Context: Understanding the collisional properties of ice is important for understanding both the early stages of planet formation and the evolution of planetary ring systems. Simple chemicals such as methanol and formic acid are known to be present in cold protostellar regions alongside the dominant water ice; they are also likely to be incorporated into planets which form in protoplanetary disks, and planetary ring systems. However, the effect of the chemical composition of the ice on its collisional properties has not yet been studied. Aims: Collisions of 1.5 cm ice spheres composed of pure crystalline water ice, water with 5% methanol, and water with 5% formic acid were investigated to determine the effect of the ice composition on the collisional outcomes. Methods: The collisions were conducted in a dedicated experimental instrument, operated under microgravity conditions, at relative particle impact velocities between 0.01 and 0.19 m s^-1, temperatures between 131 and 160 K and a pressure of around 10^-5 mbar. Results: A range of coefficients of restitution were found, with no correlation between this and the chemical composition, relative impact velocity, or temperature. Conclusions: We conclude that the chemical composition of the ice (at the level of 95% water ice and 5% methanol or formic acid) does not affect the collisional properties at these temperatures and pressures due to the inability of surface wetting to take place. At a level of 5% methanol or formic acid, the structure is likely to be dominated by crystalline water ice, leading to no change in collisional properties. The surface roughness of the particles is the dominant factor in explaining the range of coefficients of restitution

Traditional Owners and Sea Country in the Southern Great Barrier Reef – Which Way Forward?

[Extract] For over 20 years, Traditional Owners (TOs) from across the Great Barrier Reef (GBR) have been coming together to explore and call for a collective approach to achieving their aspirations for ownership, access to, and involvement in the management of sea country. Over these years, people have made real progress in securing improved recognition of their rights and developing local capacities to govern and manage their sea country. Despite these wins, and good engagement by Commonwealth and State governments on occasions, there has been no lasting, continuously improving GBR-wide approach to engaging TOs. With the future health of the GBR under threat, the current Reef 2050 Long Term Sustainability Plan (Reef 2050) recognises the significance of Traditional Owner rights and interests in the management of sea country and the Marine Park. There are considered and significant Indigenous implementation actions embedded right across Reef 2050. Implementation, however, lies ahead. Given the long history of Traditional Owner attempts to influence sea country management across the GBR, they consider that, without strong partnerships, there could be a real risk of implementation failure. At this point, the mechanisms for cohesive and coordinated implementation of the Reef 2050 do not yet fundamentally engage Traditional Owners as real partners in the long-term management of sea country, consistent with international guidelines for their engagement in protected area management, which emphasise the required for prior informed consent and ongoing equity

Hyperpolarised noble gas nuclear magnetic resonance and magnetic resonance imaging studies of complex porous media

The ability to non-invasively probe void spaces is an extremely valuable tool for applications ranging from chemical engineering to biomedical, pulmonary imaging studies. Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) provide such a methodology. To achieve suitable signal intensity from the magnetic resonance experiment, a probe molecule such as H2O is introduced to the void space to generate enough detectable signal for an MR system. The use of liquids, however, restricts the time scales accessible and confines characterisation of diffusion to that of the molecular regime. In recent years, gas phase measurements have been made with probe molecules such as sulphur hexafluoride SF6 but such measurements typically require high pressures to achieve suitable sensitivity and as such are subject to the same limitations as liquid measurements. However, via use of hyperpolarisation (hp) techniques such as Spin Exchange Optical Pumping (SEOP) it is possible to perform measurements of noble gases at atmospheric pressure and room temperature. As such, it is possible to utilise these hp gasses to investigate low-density, gas-phase mass-transport, such that the diffusion may be studied in the Knudsen regime. Understanding of diffusion processes are particularly valuable to the design of hierarchical porous media such as catalysed diesel particulate filters (DPF) and other industrial catalytic processes. The characterisation of the structure-transport relationships of porous solids is extremely valuable for the design of new advanced catalysed materials for a range of applications. The work within this document has applied a variety of MR techniques to the investigation of structure-transport relationships in complex porous media. Further new production methodologies have allowed for new, novel gas probes to be produced, further increasing applicability of hp noble gas MR techniques to probing void spaces within porous media. Hp 129Xe has been shown to be a valuable probe of flow within complex porous media via MRI phase-shift velocimetry. Measurements were performed in channels with porous walls and velocity profiles were shown to provide good correlated with theoretical models. Structure-transport relationships within the hierarchical pore structure of the DPF was probed via a multi-modal, multi nuclei-study. NMR relaxometry and MRI of gas phase 129Xe were used as to interrogate the contributions of each level of the structural hierarchy of the sample to the dispersive mass transport. A novel methodology of SEOP for the production of highly polarised 129Xe and 83Kr spin states via use of hydrogen-noble gas mixtures is presented. Catalytic separation techniques were employed for purification of the polarised spin system from its buffer gas of H2. These developments enhance the applicability of 129Xe and 83Kr to material science applications, as well as vastly increasing viability of clinical applications. Finally, SEOP of 21Ne was performed and for the first time produced a highly polarised sample, suitable for NMR spectroscopy and relaxometry studies. The quadrupolar relaxation of 21Ne was characterised in a range of void spaces and surface chemistries. 21Ne is shown to be a promising probe for investigations of porous media

Effect of floor type on the performance, physiological and behavioural responses of finishing beef steers

peer-reviewedBackground:The study objective was to investigate the effect of bare concrete slats (Control), two types of mats [(Easyfix mats (mat 1) and Irish Custom Extruder mats (mat 2)] fitted on top of concrete slats, and wood-chip to simulate deep bedding (wood-chip placed on top of a plastic membrane overlying the concrete slats) on performance, physiological and behavioral responses of finishing beef steers. One-hundred and forty-four finishing steers (503 kg; standard deviation 51.8 kg) were randomly assigned according to their breed (124 Continental cross and 20 Holstein–Friesian) and body weight to one of four treatments for 148 days. All steers were subjected to the same weighing, blood sampling (jugular venipuncture), dirt and hoof scoring pre study (day 0) and on days 23, 45, 65, 86, 107, 128 and 148 of the study. Cameras were fitted over each pen for 72 h recording over five periods and subsequent 10 min sampling scans were analysed. Results: Live weight gain and carcass characteristics were similar among treatments. The number of lesions on the hooves of the animals was greater (P < 0.05) on mats 1 and 2 and wood-chip treatments compared with the animals on the slats. Dirt scores were similar for the mat and slat treatments while the wood-chip treatment had greater dirt scores. Animals housed on either slats or wood-chip had similar lying times. The percent of animals lying was greater for animals housed on mat 1 and mat 2 compared with those housed on concrete slats and wood chips. Physiological variables showed no significant difference among treatments. Conclusions: In this exploratory study, the performance or welfare of steers was not adversely affected by slats, differing mat types or wood-chip as underfoot material

The 2 × 2 model of perfectionism and school‐ and community‐based sport participation.

The authors adopted the 2 × 2 model of perfectionism to examine the unique and interactive effects of two dimensions of perfectionism (personal standards perfectionism PSP and evaluative concerns perfectionism ECP) on personal and interpersonal indicators of participant experience in youth sport (enjoyment, physical self‐worth, and friendship quality). Participants (N = 219, M age = 15.12, SD = 2.02) were recruited from various school‐ and community‐based sports and completed a multi‐section questionnaire. Consideration of main and interaction effects indicated that pure PSP (high PSP/low ECP) was associated with the most positive sport experience and pure ECP (low PSP/high ECP) was associated with the least positive sport experience. The findings suggest that subtypes of perfectionism from the 2 × 2 model are predictive of differing experiences in youth sport participation. (PsycINFO Database Record (c) 2015 APA, all rights reserved). (journal abstract

Lesion Profiling at Primary Isolation in RIII Mice is Insufficient in Distinguishing BSE from Classical Scrapie

Primary isolation of bovine spongiform encephalopathy (BSE) in RIII mice generates a lesion profile believed to be reproducible and distinct from that produced by classical scrapie. This profile, which is characterized by peaks at gray matter areas 1, 4 and 7 (dorsal medulla, hypothalamus and septal nuclei), is used to diagnose BSE on primary isolation. The aim of this study was to investigate whether the BSE agent could be present in sheep diagnosed with classical scrapie, using lesion profiles in RIII mice as a discriminatory method. Sixty-two positive scrapie field cases were collected from individual farms between 1996 and 1999 and bioassayed in RIII mice. Fifty-five of these isolates transmitted successfully to at least one mouse. Of the 31 that produced adequate data to allow lesion profile analysis, 10 showed a consistent profile with peaks at brain areas 1, 4 and 7. All inocula for this subgroup were derived from sheep of genotype ARQ/ARQ. While the 1-4-7-scrapie profile exhibited similarities to BSE in RIII mice at primary isolation, it was distinguishable based on histopathology, immunohistochemistry and cluster analysis. We conclude that caution should be taken to distinguish this profile from BSE and that additional parameters should be considered to reach a final diagnosis

Collisions of small ice particles under microgravity conditions - II. Does the chemical composition of the ice change the collisional properties?

Context. Understanding the collisional properties of ice is important for understanding both the early stages of planet formation and the evolution of planetary ring systems. Simple chemicals such as methanol and formic acid are known to be present in cold protostellar regions alongside the dominant water ice; they are also likely to be incorporated into planets which form in protoplanetary disks, and planetary ring systems. However, the effect of the chemical composition of the ice on its collisional properties has not yet been studied.Aims. Collisions of 1.5 cm ice spheres composed of pure crystalline water ice, water with 5% methanol, and water with 5% formic acid were investigated to determine the effect of the ice composition on the collisional outcomes.Methods. The collisions were conducted in a dedicated experimental instrument, operated under microgravity conditions, at relative particle impact velocities between 0.01 and 0.19 ms-1, temperatures between 131 and 160 K and a pressure of around 10-5Results. A range of coefficients of restitution were found, with no correlation between this and the chemical composition, relative impact velocity, or temperature.Conclusions. We conclude that the chemical composition of the ice (at the level of 95% water ice and 5% methanol or formic acid) does not affect the collisional properties at these temperatures and pressures due to the inability of surface wetting to take place. At a level of 5% methanol or formic acid, the structure is likely to be dominated by crystalline water ice, leading to no change in collisional properties. The surface roughness of the particles is the dominant factor in explaining the range of coefficients of restitution