38 research outputs found

    What have we learnt from EUPORIAS climate service prototypes?

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    The international effort toward climate services, epitomised by the development of the Global Framework for Climate Services and, more recently the launch of Copernicus Climate Change Service has renewed interest in the users and the role they can play in shaping the services they will eventually use. Here we critically analyse the results of the five climate service prototypes that were developed as part of the EU funded project EUPORIAS. Starting from the experience acquired in each of the projects we attempt to distil a few key lessons which, we believe, will be relevant to the wider community of climate service developers

    Water storage in cratonic mantle

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    Knowledge of the water capacity of the deep lithosphere is crucial for validating models of craton growth and for constraining solid earth volatile cycles over geologic time. However, experimental constraints on water solubility and partitioning often disagree with natural rock data. We present a bulk compositionally dependent model of water storage capacity in pyrolite over a range of lithospheric mantle pressures and temperatures. Models are compared against published xenolith nominally anhydrous mineral (NAM) water contents, which have been recalculated to reflect the last water content of the mantle lithosphere by using coexisting pyroxene water contents in the same samples. Our main findings are that (1) regardless of tectonic setting, olivine records similar recalculated water contents, suggesting a common level of water undersaturation in the lithospheric mantle, and (2) equilibrium water partitioning between clinopyroxene and orthopyroxene (Dcpx/opx) increases down-temperature. We propose these trends may be explained by re-hydration/re-fertilization of cratonic mantle early during coalescence, followed by cooling-induced water exsolution from orthopyroxene and garnet formation as cratons thicken and stabilize

    Computational study of tetrahedral Al-Si ordering in muscovite

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    The nature of Al-Si ordering across the tetrahedral sites in muscovite, computational techniques. Values of the atomic exchange interaction parameters J1 were obtained. From these parameters, a two-dimensional Al-Si ordering scheme was deduced. The transition temperature Tc for this two-dimensional ordering is 1900 K. These are several possible ordering schemes in three dimensions, based on different stacking sequences of ordered sheets of tetrahedral sites. Monte Carlo simulations of both two-dimensional and three-dimensional ordering were performed, but in the three-dimensional simulation only the two-dimensional ordering is seen, implying that three-dimensional ordering is too slow to be attained during the timescale of the simulation. The effect of the three-dimensional interactions is to raise the two-dimensional ordering temperature to 2140 K. From the three-dimensional Monte Carlo simulation, the frequency of occurrence of 4SiOAl, 3Si1Al, 2Si2Al and 1Si3Al clusters was determined, which match those inferred by 29Si MAS-NMR measurements reasonably well. In fact, the match suggests that the cation ordering seen in experiments corresponds to a configuration with considerable short-range order but no long-range order, similar to a state that is at a temperature just above an ordering phase transition

    Computational methods for the study of energies of cation distributions: applications to cation-ordering phase transitions and solid solutions

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    The structural and thermodynamic properties of minerals are strongly affected by cation site-ordering processes. We describe methods to determine the main interatomic interactions that drive the ordering process, which are based on parameterizing model Hamiltonians using empirical interatomic potentials and/or ab initio quantum mechanics methods. The methods are illustrated by a number of case study examples, including Al/Si ordering in aluminosilicates, Mg/Ca ordering in garnets, simultaneous Al/Si and Mg/Al ordering in pyroxenes, micas and amphiboles, and Mg/Al non-convergent ordering in spinel using only quantum mechanical methods

    Application of bile acids in drug formulation and delivery

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    Bile acids are naturally produced in humans and are known to provide human health benefits through their endocrinological, microfloral, metabolic and other åffects that are still to be elucidated. In recent years, there has been a growing interest in using bile acids as absorption enhancers for drug delivery. Bile acids are amphiphilic molecules with a unique ability to facilitate and promote drug permeation through biological membranes. The role of bile acids in promoting drug permeation has been experimentally illustrated in various pharmaceutical formulations including oral, nasal, ocular, buccal, pulmonary and rectal delivery as well as through the blood–brain barrier. Recently, bile acids have drawn attention in the field of drug delivery due to their ability to act as a drug carrier system in the form of mixed micelles, bilosomes and chemical conjugates with drug molecules. Bile acids have demonstrated a unique ability to enhance the epithelial transport of hydrophilic drugs through the paracellular route and that of hydrophobic compounds through both paracellular and transcellular routes. The aim of this review is to discuss various chemical and pharmaceutical aspects of BAs and their potential applications in drug formulation and delivery
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