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Delgado Martin J.,University of La Coruna | Soler I Gil A.,Mineralogia i Diposits Minerals
European Journal of Mineralogy | Year: 2010

Two well developed hedenbergitic, ilvaite-bearing skarns formed along the northern contact of the Maladeta batholith (Central Pyrenees, Spain) have been studied in order to determine their physico-chemical conditions of formation. The skarns formed at ∼3 kbar total pressure following a classical two-stage (prograde/retrograde) evolution. Oxygen fugacity during skarn formation was buffered close to the NNO oxygen buffer while it is likely that sulfur fugacity remained nearly constant (10-8-10-10) throughout the second, retrograde stage. Fluid inclusions indicate that the hydrothermal fluid was a hypersaline brine (25-30 % NaCl eq.), sometimes halite-saturated at room temperature. Based on fluid inclusions and volatile speciation calculations, H2O was the dominating volatile while CO2 was present in low levels (Xco2 < 0.02). Thermodynamic data for ilvaite have been retrieved from published works and available experiments. These data have made possible the construction of several phase diagrams for the Ca-FeSi-O-H ± C system with which the stability of ilvaite with respect to a number of parameters is illustrated. The stability relationships render unlikely that ilvaite can form under pressures below 2 kbar and show that this mineral can only develop from fluids with low or very low CO2 content. With the exception of Mn, the presence of significant amounts of Al, Mg and other elements drastically reduces the stability field of ilvaite. Hence, this mineral should not be expected to occur in environments departing significantly from the 6-component system studied here. © 2010 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart. Source


Alba A.-N.R.,University of Barcelona | Valero G.,University of Barcelona | Calbet T.,Mineralogia i Diposits Minerals | Calbet T.,University of Barcelona | And 5 more authors.
New Journal of Chemistry | Year: 2012

The catalytic enantioselective addition of 2-tert-butyl-4-aryl-1,3-oxazol- 5-ones to maleimides is reported. The addition takes place exclusively at the C-4 position of the oxazolone ring, giving access to quaternary amino acid derivatives. The reaction is catalyzed by readily available chiral bases such as (DHQD) 2PYR, rendering the final compounds in good yields and with moderate to good diastereo- and enantioselectivities. When the C-4-substituent of the 2-tert-butyl-oxazolone is an alkyl group, the regioisomeric C-2 addition product is also obtained. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012. Source


Escribano E.,University of Barcelona | Font-Bardia M.,Mineralogia i Diposits Minerals | Font-Bardia M.,University of Barcelona | Calvet T.,Mineralogia i Diposits Minerals | And 4 more authors.
Inorganica Chimica Acta | Year: 2013

A series of platinum(II) complexes of formulae cis-[Pt(Am) 2X2] (where Am represents an inert amine and X a labile (carboxylato) ligand) have been prepared and characterized by elemental analysis, ESI-MS, IR and 1H NMR spectroscopy. The single-crystal molecular structures were determined for cis-[Pt(opea)(cbdca-2H)], cis-[Pt(hmpy)(cbdca-2H)], cis-[Pt(NH3)2(bzmal-2H)] and cis-[Pt(hmpy)(μ-dcch-2H)2] (where opea is picolylamine, hmpy represents 4-hydroxymethylpyridine, cbdca-2H, is 1,1-cyclobutanedicarboxylate anion, bzmal-2H stands for benzylmalonate anion and dcch-2H is trans-1,2-cyclohexanedicarboxylate anion). The interaction of all compounds with DNA was investigated with different techniques: viscosity measurements and emission fluorescence spectroscopy were used to investigate the changes induced by the binding of the platinum compounds to calf-thymus DNA, while atomic force microscopy and electrophoretic mobility allowed evaluating the potential alterations of pBR322 plasmid DNA. The cytotoxic behavior of the platinum compounds on human leukemia HL-60 tumor cell lines was also examined. © 2012 Elsevier B.V. All rights reserved. Source


Bayes-Garcia L.,Mineralogia i Diposits Minerals | Ventola L.,Mineralogia i Diposits Minerals | Cordobilla R.,Mineralogia i Diposits Minerals | Benages R.,Mineralogia i Diposits Minerals | And 2 more authors.
Solar Energy Materials and Solar Cells | Year: 2010

In this study, phase change materials (Rubitherm® RT 27) microcapsules were successfully obtained by two different methods. The main difference between them remains on the shell composition, as they are composed of different coacervates (Sterilized Gelatine/Arabic Gum for the SG/AG method and Agar-Agar/Arabic Gum for the AA/AG method). Microcapsules were thermally characterized by thermo-optical microscopy and differential scanning calorimetry. Using scanning electron microscopy, their spherical morphology (sphericity factor of 0.94-0.95) and their particle size distribution were determined, obtaining an average diameter of 12 μm for the SG/AG method and lower values for the AA/AG method, where nanocapsules were also observed (average diameter of 4.3 μm for the microcapsules and 104 nm for the nanocapsules). The thermal stability determination was carried out by Thermogravimetric analyses (TG) and the results show a high decomposition temperature, although the process takes places in four steps for the two mentioned methods. Moreover, the microcapsules obtained by the AA/AG method decompose in a more gradual way, as in the TG results a double step, instead of one, is appreciable. On the whole, the prepared microencapsulated PCM are totally capable of developing their role in thermal energy storage. © 2010 Elsevier B.V. All rights reserved. Source

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