41 resultados para rare minnow
Resumo:
Despite being the most suitable candidates for solenoid pole pieces in state-of-the-art superconductor- based electromagnets, the intrinsic magnetic properties of heavy rare earth metals and their alloys have gained comparatively little attention. With the potential of integration in micro- and nanoscale devices, thin films of Gd, Dy, Tb, DyGd and DyTb were plasma-sputtered and investigated for their in-plane magnetic properties, with an emphasis on magnetisation vs. temperature profiles. Based on crystal structure analysis of the polycrystalline rare earth films, which consist of a low magnetic moment FCC layer at the seed interface topped with a higher moment HCP layer, an experimental protocol is introduced which allows the direct magnetic analysis of the individual layers. In line with the general trend of heavy lanthanides, the saturation magnetisation was found to drop with increasing unit cell size. In-situ annealed rare earth films exceeded the saturation magnetisation of a high-moment Fe65Co35 reference film in the cryogenic temperature regime, proving their potential for pole piece applications; however as-deposited rare earth films were found completely unsuitable. In agreement with theoretical predictions, sufficiently strained crystal phases of Tb and Dy did not exhibit an incommensurate magnetic order, unlike their single-crystal counterparts which have a helical phase. DyGd and DyTb alloys followed the trends of the elemental rare earth metals in terms of crystal structure and magnetic properties. Inter-rare-earth alloys hence present a desirable blend of saturation magnetisation and operating temperature.
Resumo:
Congenital anomalies (CA) are the paradigm example of rare diseases liable to primary prevention actions due to the multifactorial etiology of many of them, involving a number of environmental factors together with genetic predispositions. Yet despite the preventive potential, lack of attention to an integrated preventive strategy has led to the prevalence of CA remaining relatively stable in recent decades. The 2 European projects, EUROCAT and EUROPLAN, have joined efforts to provide the first science-based and comprehensive set of recommendations for the primary prevention of CA in the European Union. The resulting EUROCAT-EUROPLAN 'Recommendations on Policies to Be Considered for the Primary Prevention of Congenital Anomalies in National Plans and Strategies on Rare Diseases' were issued in 2012 and endorsed by EUCERD (European Union Committee of Experts on Rare Diseases) in 2013. The recommendations exploit interdisciplinary expertise encompassing drugs, diet, lifestyles, maternal health status, and the environment. The recommendations include evidence-based actions aimed at reducing risk factors and at increasing protective factors and behaviors at both individual and population level. Moreover, consideration is given to topics specifically related to CA (e.g. folate status, teratogens) as well as of broad public health impact (e.g. obesity, smoking) which call for specific attention to their relevance in the pre- and periconceptional period. The recommendations, reported entirely in this paper, are a comprehensive tool to implement primary prevention into national policies on rare diseases in Europe.
Resumo:
BACKGROUND: The past three decades have seen rapid improvements in the diagnosis and treatment of most cancers and the most important contributor has been research. Progress in rare cancers has been slower, not least because of the challenges of undertaking research.
SETTINGS: The International Rare Cancers Initiative (IRCI) is a partnership which aims to stimulate and facilitate the development of international clinical trials for patients with rare cancers. It is focused on interventional--usually randomized--clinical trials with the clear goal of improving outcomes for patients. The key challenges are organisational and methodological. A multi-disciplinary workshop to review the methods used in ICRI portfolio trials was held in Amsterdam in September 2013. Other as-yet unrealised methods were also discussed.
RESULTS: The IRCI trials are each presented to exemplify possible approaches to designing credible trials in rare cancers. Researchers may consider these for use in future trials and understand the choices made for each design.
INTERPRETATION: Trials can be designed using a wide array of possibilities. There is no 'one size fits all' solution. In order to make progress in the rare diseases, decisions to change practice will have to be based on less direct evidence from clinical trials than in more common diseases.
Resumo:
A novel electrical current applied technique known as flash sintering has been applied to rapidly (within 10 min) densify electrolytes including Ce0.8Gd0.2O1.9 (GDC20), Ce0.9Gd0.1O1.95 (GDC10), and Ce0.8Sm0.2O1.9 (SDC20) for application in Solid Oxide Fuel Cells (SOFCs). The densification temperature for the three electrolytes was 554°C, 635°C, and 667°C, respectively, which is far below conventional sintering temperatures. All specimens after flash sintering maintained the pure fluorite structure and exhibited a well-densified microstructure. To investigate the flash-sintering mechanism, we have applied Joule heating effect with blackbody radiation theory, and found that this theory could reasonably interpret the flash-sintering phenomenon by matching theoretically calculated temperature with the real temperature. More importantly, one of the materials inherent properties, the electronic conductivity, has been found correlated with the onset of flash sintering, which indicates that the electrons and holes are the primary current carriers during the start of flash-sintering process. As a result, potential densification mechanisms have been discussed in terms of spark plasma discharge.
Resumo:
A range of liquid rare-earth chlorometallate complexes with alkyl-phosphonium cations, [P666 14]+, has been synthesised and characterised. EXAFS confirmed the predominant liquid-state speciation of the [LnCl6]3- of the series with Ln = Nd, Eu, Dy. The crystal structure of the shorter-alkyl-chain cation analogue [P4444]+ has been determined and exhibits a very large unit cell. The luminescence properties, with visible light emissions of the liquid Tb, Eu, Pr and Sm and the NIR emissions for the Nd and Er compounds were determined. The effective magnetic moments were measured and fitted for the Nd, Tb, Ho, Dy, Gd and Er samples.
Resumo:
Aim: Our primary aim is to understand how assemblages of rare (restricted range) and common (widespread) species are correlated with each other among different taxa. We tested the proposition that marine species richness patterns of rare and common species differ, both within a taxon in their contribution to the richness pattern of the full assemblage and among taxa in the strength of their correlations with each other. Location The UK intertidal zone. Methods: We used high-resolution marine datasets for UK intertidal macroalgae, molluscs and crustaceans each with more than 400 species. We estimated the relative contribution of rare and common species, treating rarity and commonness as a continuous spectrum, to spatial patterns in richness using spatial crosscorrelations. Correlation strength and significance was estimated both within and between taxa. Results: Common species drove richness patterns within taxa, but rare species contributed more when species were placed on an equal footing via scaling by binomial variance. Between taxa, relatively small sub-assemblages (fewer than 60 species) of common species produced the maximum correlation with each other, regardless of taxon pairing. Cross-correlations between rare species were generally weak, with maximum correlation occurring between small sub-assemblages in only one case. Cross-correlations between common and rare species of different taxa were consistently weak or absent. Main conclusions: Common species in the three marine assemblages were congruent in their richness patterns, but rare species were generally not. The contrast between the stronger correlations among common species and the weak or absent correlations among rare species indicates a decoupling of the processes driving common and rare species richness patterns. The internal structure of richness patterns of these marine taxa is similar to that observed for terrestrial taxa.