Search results for "ALCA"

Carbonate deposition and diagenesis in evaporitic environments: The evaporative and sulphur-bearing limestones during the settlement of the Messinian…

2015

The depositional and diagenetic processes involved in the formation of carbonates in the evaporitic environment of the Messinian Salinity Crisis are investigated in Southern Italy (Sicily and Calabria). Strong differences are observed between the studied sections that reflect specific depositional and diagenetic evolution in the interconnected sub-basins resulting from the syn-sedimentary tectonic fragmentation of the Central Sicilian and Calabrian domains. These carbonates formed diachronously in restricted perched sub-basins between the Tripoli Formation and the hypersaline settings of the MSC. The Calcare di Base (CdB) that can be interbedded with gypsum layers occurs rhythmically at the…

Sinkholes risk analysis: case history of Marsala (Sicily, Italy)

2006

Given the increasing phenomenon of Sinkholes all over Italy, the Gruppo Nazionale per la Difesa dalle Catastrofi Idrogeologiche (G.N.D.C.I) and the Dipartimento della Protezione Civile (D.P.C.), during 2004, started a plan called Sinkholes dedicated to the phenomena in Italy. The plan provides the publication of the database realized by the D.P.C. by means of the census of beyond 1000 cases scattered across the nation. The city of Marsala is strongly characterized by the presence of a great number of Calcarenite cavities. The material object of extraction is the Calcarenite di Marsala of the Pleistocene, frequently used in the construction of buildings. The presence of the underground cavit…

Preliminary Results on Recent Calcareous nannofossil Assemblages from the Central Mediterranean

2009

Response of calcareous nannofossils to late Quaternary orbital and suborbital climate changes: Evidence from central Mediterranean and Iberian Margin…

2009

Pseudomorphic transformation of amorphous calcium carbonate films follows spherulitic growth mechanisms and can give rise to crystal lattice tilting

2015

Amorphous calcium carbonate films synthesized by the polymer-induced liquid-precursor (PILP) process convert into crystallographically complex calcite spherulites. Tuning the experimental parameters allows for the generation of crystal lattice tilting similar to that found in calcareous biominerals. This contribution evidences the role of spherulitic growth mechanisms in pseudomorphic transformations of calcium carbonate.

Flexible minerals: self-assembled calcite spicules with extreme bending strength.

2013

Flexi-Fibers Glass or metal fibers can show incredible flexibility. Natalio et al. (p. 1298 ; see the Perspective by Sethmann ) used the protein silicatein-α, which is responsible for the biomineralization of silicates in sponges, to guide the formation of spicules made of calcite. These synthetic spicules could be bent to a high degree because of their inherent elasticity, whilst retaining the ability to guide light.

The sponge silicatein-interacting protein silintaphin-2 blocks calcite formation of calcareous sponge spicules at the vaterite stage

2013

Ca-carbonate, the inorganic matrix of the spicules from the calcareous sponges, is formed as the result of an enzyme-catalyzed reaction with the carbonic anhydrase [CA] as a decisive component. The growth and the morphology of the spicules are genetically controlled, and are taxon-specific. In the present study it is shown that the silicatein-interacting protein silintaphin-2 is present at the surface of the siliceous spicules of the demosponge Suberites domuncula and prevents the association of calcareous crystals synthesized in vitro to these skeletal elements. Silintaphin-2 comprises a Ca2+-binding domain that is formed by a 22 amino acid-long peptide, N-DDDSQGEIQSDMAEEEDDDNVD-C. This ve…

The Understanding of the Metazoan Skeletal System, Based on the Initial Discoveries with Siliceous and Calcareous Sponges

2017

Initiated by studies on the mechanism of formation of the skeletons of the evolutionary oldest still extant multicellular animals, the sponges (phylum Porifera) have provided new insights into the mechanism of formation of the Ca-phosphate/hydroxyapatite skeleton of vertebrate bone. Studies on the formation of the biomineral skeleton of sponges revealed that both the formation of the inorganic siliceous skeletons (sponges of the class of Hexactinellida and Demospongiae) and of the calcareous skeletons (class of Calcarea) is mediated by enzymes (silicatein: polymerization of biosilica; and carbonic anhydrase: deposition of Ca-carbonate). Detailed studies of the initial mineralization steps i…

Dolarización panamericana

2001

Carlo V e la città di Alcamo

2012

Nell’estate del 1535 Carlo V, reduce dalla vittoriosa impresa di Tunisi faceva ritorno in Sicilia. Dopo essersi trattenuto a Trapani e prima di raggiungere Monreale, lungo il tragitto fra Trapani e Palermo, l’imperatore e il suo seguito sostavano per alcuni giorni ad Alcamo, un piccolo centro che faceva parte dei possedimenti siciliani del conte di Modica, Fadrique Enriquez grande Almirante di Castiglia. Ben poco sappiamo dell’ingresso e del breve soggiorno del monarca in città di cui riferiscono le fonti, ma possiamo immaginare la portata dell’evento e l’effetto a distanza che l’episodio ha prodotto nella realtà urbana innescando una serie di iniziative pubbliche intrapresa dopo questa dat…