In this work the synthesis, characterization and evaluation of a novel sorbent material used for the solid-phase extraction of titanium (IV) from hydrochloric acid medium is described. The material was prepared by the sol-gel route incorporating bis(2-ethylhexylphos-phoric acid) (D2EHPA) as extractant within a polymeric matrix based on polysiloxanes and characterized through FTIR-ATR, XRD, 29Si and 31P NMR, TGA and DSC. In studies of titanium sorption and desorption in batch mode several factors related with the extraction and back-extraction operations were evaluated, such as: contact time, titanium concentration, nature and composition of the aqueous media, and extractant concentration in the sorbent. The maximum sorption was observed at 30 min of contact time in a 1 mol L-1 HC1 + 0.1% KC1 medium, while the maximum desorption was observed at 60 min in a 1.5 mol L-1 H2SO4 + 20% v/v H2O2 medium when titanium concentration was 70 mg L-1. Under optimal conditions the recovered percent of titanium was nearly 90%. In addition, the characterization of the extraction equilibrium was performed. The selectivity of the method was studied adding Al(III), Fe(III) and V(V) to the extraction medium. A high selectivity for Ti over Al and Fe was observed, even at high concentrations of the interferents; 50% of Ti, only 7%o of Fe, 3% of Al and less than 1% of V were recovered under the established conditions. The method was finally applied for titanium recovery from a certified fly ash sample generated from a municipal incineration plant.

Se describe la síntesis, caracterización y evaluación de un material adsorbente novedoso utilizado para la extracción en fase sólida de titanio (IV) a partir de medio de ácido clorhídrico. El material se sintetizó mediante la técnica de sol gel, incorporando el ácido bis(2-etilhexilfosfórico) (D2EHPA) como extractante dentro de una matriz polimérica a base de polisiloxanos y fue caracterizado mediante FTIR-ATR, XRD, 29Si y 31P NMR, TGA y DSC (por las siglas en inglés). En los estudios de sorción y desorción en lote de titanio se evaluaron diversos parámetros relacionados con las operaciones de extracción y re-extracción tales como: tiempo de contacto, concentración de titanio, naturaleza y concentración de los medios acuosos, y concentración del extractante en el material sorbente. La máxima sorción se presentó a los 30 min de contacto en un medio HC1 1 mol L-1 + KC1 0.1%, mientras que la máxima desorción ocurrió a un tiempo de 60 min en un medio compuesto de H2SO4 1.5 mol L-1 + H2O2 20%) v/v para una solución que contenía 70 mg L-1 de titanio (IV). En condiciones óptimas el porcentaje de recuperación de Ti(IV) fue cercano a 90%. Adicionalmente, se realizó la caracterización del equilibrio de extracción. La selectividad del método se estudió adicionando los cationes Al(III), Fe(III) y V(V) al medio de extracción. Se observó que el método fue selectivo para titanio incluso a concentraciones muy elevadas de Al y Fe bajo las condiciones establecidas, obteniendo una recuperación de 50%o del titanio inicial en comparación al 7% de Fe, 3% de Al y menos del 1% de V. Finalmente el método se aplicó para la recuperación de titanio de una muestra real certificada de cenizas de un incinerador municipal de desechos.

Free radicals are extremely reactive and produce damage and modify cell functions. Furthermore, superoxide dismutase and catalase are believed to play a key role in the enzymatic defence of the cells. Indeed, some authors have argued that reduced free-radical damage could explain increased longevity. Margaritifera margaritifera is one of the longest-lived animals in the world (up to 100-200 years). Furthermore, this organism may serve as a useful model for gerontologists interested in exploring the mechanisms that promote long life and the slowing of senescence. The present study estimated for the first time individual enzymatic activity for superoxide dismutase isozymes (Cu,Zn-SOD and Mn-SOD) and catalase in tissue preparations of gills, digestive glands and mantles of two natural populations of M. margaritifera. Superoxide dismutase activities showed significant differences in the tissues analysed of specimens from the same river and in specimens from different rivers for the same tissue. Catalase activity levels also showed significant variation, but differences among tissues, within tissues or between rivers were of relatively little interest. We failed to find any relationship between individual enzymatic activities and the age estimated for each mussel. Indeed, the wide variation found in activity levels can be principally interpreted as an adaptation to the unpredictable and changing nature of freshwater natural habitats.

The aim of this study was to analyze the morphological variation of brown trout (Salmo trutta) in the Duero basin, an Atlantic river basin in the Iberian Peninsula, where a spatial segregation of two divergent lineages was previously reported, based on isozyme, microsatellite and mtDNA data. In these studies, two divergent pure regions (Pisuerga and Lower-course) and several hybrid populations between them were identified. Morphological variation was evaluated in 11 populations representative of the genetic differentiation previously observed in the Duero basin, using multivariate analysis on 12 morphometric and 4 meristic traits. A large differentiation between populations was observed (interpopulation component of variance: 41.8%), similar to that previously detected with allozymes and microsatellites. Morphometric differentiation was also reflected by the high classification success of pure and hybrid individuals to their respective populations, using multivariate discriminant functions (94.1% and 79.0%, respectively). All multivariate and clustering analyses performed demonstrated a strong differentiation between the pure regions. The hybrid populations, though showing large differentiation among them, evidenced an intermediate position between the pure samples. Head and body shape traits were the most discriminant among the morphometric characters, while pectoral rays and gillrakers were the most discriminant among the meristic traits. These results confirmed the high divergence of the brown trout from the Duero basin and suggest some traits on which selection could be acting to explain the spatial segregation observed.