Synchrotron X-ray microscopy of marine calcifiers: how plankton record past climate change

We have used STXM and PEEM to reveal the underpinning chemistry and nanoscale structure behind palaeo-climate geochemical signatures, such as trace Mg in shells- proposed proxies for palaeo-ocean temperature. This has allowed us to test the chemical assumptions and mechanisms underpinning the use of such empirical proxies. We have determined the control on driving chemical variations in biogenic carbonates using STXM at the absorption edge of Mg, B, and Na in the shells of modern plankton. The power of these observations lies in their ability to link changes in chemistry, microstructure, and growth process in biogenic carbonate to environmental influences. We have seen that such changes occur at length scales of tens of nanometres and demonstrated that STXM provides an invaluable route to understanding chemical environment and key heterogeneity at the appropriate length scale. This new understanding provides new routes for future measurements of past climate variation in the sea floor fossil record

Spontaneous strain and the ferroelastic phase transition in As,O

Abstract. The tetragonalarthorhombic phase transition in arsenic pentoxide has been studied by x-ray powder diffraction and is found to be a proper ferroelastic transition. The spontaneous strain behaves as the order parameter following Landau theory with E, CL IT, -TIs, 6 = 1, T, = 578 K. The order parameter susceptibility has been determined from line broadening and follows IT, -TI-7, y = 1. No deviation from Landau behaviour has been observed experimentally

Structure and elastic properties of Mg(OH)2_2 from density functional theory

The structure, lattice dynamics and mechanical properties of the magnesium hydroxide have been investigated with static density functional theory calculations as well as \it {ab initio} molecular dynamics. The hypothesis of a superstructure existing in the lattice formed by the hydrogen atoms has been tested. The elastic constants of the material have been calculated with static deformations approach and are in fair agreement with the experimental data. The hydrogen subsystem structure exhibits signs of disordered behaviour while maintaining correlations between angular positions of neighbouring atoms. We establish that the essential angular correlations between hydrogen positions are maintained to the temperature of at least 150 K and show that they are well described by a physically motivated probabilistic model. The rotational degree of freedom appears to be decoupled from the lattice directions above 30K

H2O and the dehydroxylation of phyllosilicates: an infrared spectroscopic study

As shown by in situ infrared spectroscopy and analysis of quenched samples, phyllosilicates (muscovite, sericite, pyrophyllite, and talc) under dehydroxylation conditions lack the characteristic bands near 1600 cm–1 (bending) and 5200 cm–1 (combination) of H2O, and they contain virtually no H2O but an abundance of OH. This observation appears to be at variance with the formal description of dehydroxylation in bulk samples as 2(OH) -> H2O + O, whereas it is suggested that hydrogen diffuses in the form of (OH) – or/and H+ in dehydroxylation. The upper limit of H2O in the dehydroxlated bulk is likely to be at the parts per million level in phyllosilicates that contain structural OH ions equivalent to 4–5 wt% H2O. The observations suggest that H2O molecules are probably formed near the surface of the sample

Phase diagram and phase transitions in ferroelectric tris-sarcosine calcium chloride and its brominated isomorphs

Tris-sarcosine calcium chloride [(TSCC), (CH3NHCH2COOH)3CaCl2] is a uniaxial ferroelectric (FE) with a displacive second-order phase transition near Tc=130 K. A continuous range of solid solutions can be made by substituting Br for Cl, which lowers Tc to 0 K at ∼72% Br. Such a quantum critical point differs from that in pseudocubic FEs, such as O-18 SrTiO3 or doped KTaO3. For many years, this system was thought to have only two phases, paraelectric and FE, at ambient pressure. However, we find from dielectric and resonant ultrasound spectroscopy that there are four phase transitions in TSCC and in TSCC:Br (for 0 < Br < 40%): Order-disorder of the sarcosine methyl group at 185 K; displacive FE transition at 130 K (in pure TSCC); a second FE transition [previously hypothesized to be antiferroelectric (AFE) but probably not] at 64 K; and a new anomaly at ∼45 K which might be due to a phase transition or to Debye-like freezing of orientational disorder of some part of the sarcosine molecule. The probable sequence of structures is (upon cooling): Pnma with Z=4(D2h16) ambient 500 K > T > 185 K, disordered; Pnma with Z=4(D2h16)185 K>T>130 K (ordered); Pn21a with Z=4(C2v9)130 K>T>64 K (FE); P21a (C2h5) with Z =4, 64 K > T > 45 K (not AFE); T < 45 K, unknown structure. A sixth hexagonal structure at high temperatures (>500 K) is hypothesized to be D6h3(P63/mcm) with Z =2, but the samples decompose first at 503 K (230 °C)

Low-temperature behaviour of ammonium ion in buddingtonite [N(D/H) 4 AlSi 3 O 8 ] from neutron powder diffraction

The structural response of buddingtonite [N(D/H) 4 AlSi 3 O 8 ] on cooling has been studied by neutron diffraction. Data have been collected from 280 K down to 11 K, and the crystal structure refined using the Rietveld method. Rigid-body constraints were applied to the ammonium ion to explore the structural properties of ammonium in the M-site cavities at low-temperature. Low-temperature saturation is observed for almost all the lattice parameters. From the present in situ low-temperature neutron diffraction studies, there is no strong evidence of orientational order–disorder of the ammonium ions in buddingtonite.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46909/1/269_2004_Article_425.pd

Implementing Kanyini GAP, a pragmatic randomised controlled trial in Australia: Findings from a qualitative study

© 2015 Liu et al. Background: Pragmatic randomised controlled trials (PRCTs) aim to assess intervention effectiveness by accounting for 'real life' implementation challenges in routine practice. The methodological challenges of PRCT implementation, particularly in primary care, are not well understood. The Kanyini Guidelines Adherence to Polypill study (Kanyini GAP) was a recent primary care PRCT involving multiple private general practices, Indigenous community controlled health services and private community pharmacies. Through the experiences of Kanyini GAP participants, and using data from study materials, this paper identifies the critical enablers and barriers to implementing a PRCT across diverse practice settings and makes recommendations for future PRCT implementation. Methods: Qualitative data from 94 semi-structured interviews (47 healthcare providers (pharmacists, general practitioners, Aboriginal health workers; 47 patients) conducted for the process evaluation of Kanyini GAP was used. Data coded to 'trial impact', 'research motivation' and 'real world' were explored and triangulated with data extracted from study materials (e.g. Emails, memoranda of understanding and financial statements). Results: PRCT implementation was facilitated by an extensive process of relationship building at the trial outset including building on existing relationships between core investigators and service providers. Health providers' and participants' altruism, increased professional satisfaction, collaboration, research capacity and opportunities for improved patient care enabled implementation. Inadequate research infrastructure, excessive administrative demands, insufficient numbers of adequately trained staff and the potential financial impact on private practice were considered implementation barriers. These were largely related to this being the first experience of trial involvement for many sites. The significant costs of addressing these barriers drew study resources from the task of achieving recruitment targets. Conclusions: Conducting PRCTs is crucial to generating credible evidence of intervention effectiveness in routine practice. PRCT implementation needs to account for the particular challenges of implementing collaborative research across diverse stakeholder organisations. Reliance on goodwill to participate is crucial at the outset. However, participation costs, particularly for organisations with little or no research experience, can be substantial and should be factored into PRCT funding models. Investment in a pool to fund infrastructure in the form of primary health research networks will offset some of these costs, enabling future studies to be implemented more cost-effectively. Trial registration:ACTRN12608000583334

RESPOND – A patient-centred program to prevent secondary falls in older people presenting to the emergency department with a fall: Protocol for a multi-centre randomised controlled trial

Introduction: Participation in falls prevention activities by older people following presentation to the Emergency Department (ED) with a fall is suboptimal. This randomised controlled trial (RCT) will test the RESPOND program which is designed to improve older persons’ participation in falls prevention activities through delivery of patient-centred education and behaviour change strategies. Design and setting: An RCT at two tertiary referral EDs in Melbourne and Perth, Australia. Participants: Five-hundred and twenty eight community-dwelling people aged 60-90 years presenting to the ED with a fall and discharged home will be recruited. People who: require an interpreter or hands-on assistance to walk; live in residential aged care or >50 kilometres from the trial hospital; have terminal illness, cognitive impairment, documented aggressive behaviour or history of psychosis; are receiving palliative care; or are unable to use a telephone will be excluded. Methods: Participants will be randomly allocated to the RESPOND intervention or standard care control group. RESPOND incorporates: (1) home-based risk factor assessment; (2) education, coaching, goal setting, and follow-up telephone support for management of one or more of four risk factors with evidence of effective intervention; and (3) healthcare provider communication and community linkage delivered over six months. Primary outcomes are falls and fall injuries per-person-year. Discussion: RESPOND builds on prior falls prevention learnings and aims to help individuals make guided decisions about how they will manage their falls risk. Patient-centred models have been successfully trialled in chronic and cardiovascular disease however evidence to support this approach in falls prevention is limited. Trial registration. The protocol for this study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12614000336684)