117,829 research outputs found
Tortonian-Pleistocenic oceanic features in the Southern Tyrrhenian Sea: magnetic inverse model of the Selli-Vavilov region
No full textWe show the magnetic model of the Selli-Vavilov region. The Selli Line is known as the northwestern edge of the southern Tyrrhenian basin. The tectonic evolution of the Tyrrhenian basin is dominated by a Tortonian - Quaternary extension through the eastward movement of the Apennine subduction system. This migration has generated a diffuse stretching of the continental crust with the emplacement of new oceanic material. This latter occurred in several localized zones where the eastward retreating of the Ionian subduction system produced a strong depletion of the crust with formation of basins and correlated spreading. Nowadays the presence of oceanic crust is confirmed through direct drilling investigation but a complete mapping of the oceanic crustal distribution is still lacking. The Selli-Vavilov region shows a differentiated crustal setting where seamount structures, the oceanic basement portions and continental crust blocks are superimposed. To this aim, a 2D inversion of the magnetic data of this region was conducted to define buried structures. The magnetic susceptibility pattern was computed by solving the least squares problem of the misfit between the predicted and real data for separated wavebands. This method produced two 2D models of the high and low frequency fields of the Selli-Vavilov region. The two apparent susceptibility maps provide different information for distinct ranges of depth. The results of the inversions were also combined with seismic data of the Selli region highlighting the position of the highly-magnetized buried bodies. The results confirm a role for the Selli Line as a deep crustal boundary dividing the Sardinian passive domain from the easternmost active region where different oceanic structures are located. The Selli Line has worked as a detachment fault system which has moved eastward. Finally, the Selli-Vavilov region may be interpreted as a tectonic result due to a passive asymmetrical rift occurred between the Tortonian and Pliocene.Published251-2662.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive3.4. Geomagnetismo3.5. Geologia e storia dei sistemi vulcaniciJCR Journalreserve
The Belluno Thrust between Monte Coppolo and Monte Agaro (Eastern Southern Alps, Northern Italy)
No full textThe Eastern Southern Alps are a southverging postcollisional thin skinned chain, which develop between Periadriatic
Lineament and Venetian Plain in Northern Italy. Four are the main thrusts building the chain: Marmolada, Valsugana,
Belluno and Bassano Thrusts. Marmolada is a pellicular structure involving Upper Permian-Middle Triassic succession;
Belluno represents the propagation of Valsugana indentation involving the crystalline basement intruded by Lower
Permian Cima d’Asta body; Bassano and Montello are the more recent foothills structures. All these thrusts are N90 to
N70 oriented, propagating southwards from Early Miocene to Recent (Castellarin et al., 2006). At M. Coppolo the
stratigraphic sequence includes the peritidal dolostones of Upper Triassic Dolomia Principale and the peritidal limestones
of Calcari Grigi Group. It includes M. Zugna Fm. with abundant chert nodules, defining a strong subtidal environment,
Loppio Oolite, Rotzo Fm. and Toarcian Grigno Oolite (Trevisani, 1991), very similar to Massone Oolite of Sarca Valley.
These oolitic bars mark the western and eastern border of Trento Platform during Lias. Aalenian encrinites of San Vigilio
Oolite, Middle-Upper Jurassic Rosso Ammonitico, Lower Cretaceous Maiolica and Upper Cretaceous Scaglia Rossa Fms
follow, marking the final drowing of Trento Platform causing pelagic conditions. The Belluno Thrust (BT), W-E oriented,
extends from Pieve Tesino to Caporetto bordering the northern margin of Belluno syncline (D’Alberto et al., 1995). BT
is highlighted by anticline of M. Coppolo–M. Agaro, involving the entire stratigraphic succession with the northern limb
gently dipping northwards (Brocon Pass) and the southern one vertical to overturned. The Belluno Thrust split into three
southverging structures from North to South: M. Piad Line, a steep deepening reverse fault cutting the M. Coppolo
Anticline hinge; Sasso Falares Line dipping 50° northwards along which the Coppolo Anticline thrusts over the Calcari
Grigi-Maiolica succession arranged in an another anticline representing the Sasso Falares-Val Nuvola Duplex (SFVND);
Belluno Line s.s. dipping 30° northwards, along which M. Zugna Fm. thrusts over Maiolica, bordering southwards the
SFVND. The shortening is about 5-6 km. A new outcrop of BT at Pugnai shows the architecture of thrust.
Castellarin A., Nicolich R., Fantoni R., Cantelli L., Sella M. & Selli L. 2006. Structure of the lithosphere beneath the Eastern Alps (Southern Sector of
the TRANSALP Transect).Tectonophysics 414, 259-282.
D’Alberto L., Boz A. & Doglioni C., 1995. Structure of the Vette Feltrine (Eastern Southern Alps). Mem. Sci. Geol., 47, 189-199. Trevisani, E., 1991:
Il Toarciano-Aaleniano nei settori centro-orientali della Piattaforma di Trento (Prealpi Venete). Rivista Italiana di Paleontologia e Stratigrafia, 971,
99-124
Thrusts of the Mezzocorona-Mendola pass area (Southern Alps). Structural analysis and kinematic reconstruction
No full textComparison between the surface acidity of solid catalysts determined by TPD and FTIR analysis of pre-adsorbed pyridine
No full textA series of both crystalline (Y zeolites, beta zeolites and mordenites) and amorphous alumino-silicates were investigated by means of temperature-programmed desorption with mass spectrometry detection (TPD-MS) and of Fourier transform infra-red (FTIR) analysis of adsorbed pyridine, in order to compare the surface concentration of acid sites potentially involved in a specific catalytic process, as determined through the two techniques. Up to three distributions of acid sites were evidenced in the investigated catalysts by deconvolution of the TPD-MS spectra recorded after pyridine adsorption at different temperatures (150-300 degrees C), depending on the type of catalyst and on its dealumination degree. FTIR analysis showed that pyridine adsorption on acid solids occurs under kinetic control and that equilibrium attainment implies a redistribution of pyridine molecules between Bronsted and Lewis surface sites. The reliability of the two titration techniques was verified by the good match between the values of overall surface acidity determined through them under equilibrium conditions at 150 degrees C. (C) 1999 Elsevier Science B.V. All rights reserved
Photocatalytic hydrogen production by liquid- and gas-phase reforming of CH3OH over flame-made TiO2 and Au/TiO2
No full textTiO2 and 1% Au/TiO2 powders, synthesised by flame spray pyrolysis and possessing high specific surface area (106 m2 g 1) and anatase content (ca. 90%), were tested as photocatalysts in hydrogen production frommethanol photoreforming, employing a closed recirculation apparatus. The irradiated photoreactor consisted either in a quartz vessel containing an aqueous suspension of the photocatalyst, or in a newly set-up Plexiglas cell, containing the same amount of catalyst immobilised on quartz grains, which was continuously fed with methanol/water vapours. The gas-phase composition during irradiation was analysed by gas chromatography and quadrupolar mass spectrometry, which allowed the identification of formaldehyde as the only intermediate species. The photocatalytic activity of the flame-made materials was higher than that of commercial Degussa P25 TiO2 and of 1% Au/P25 obtained via deposition of preformed gold nanoparticles on P25. In particular, a 30 times higher photocatalytic hydrogen production was obtained upon gold addition to TiO2. Furthermore, a 30% higher reaction rate
was attained with the vapour phase reactor, i.e. in the absence of liquid-phase mass transfer rate limitations, ensuring the production of up to 10.2 mmol of H2 h- 1 g- 1, with an apparent photon efficiency of 6.3%
TiO2-based materials for photocatalytic hydrogen production
No full textHydrogen can be produced photocatalytically employing titanium dioxide-based materials, either through photocatalytic water splitting, or through photocatalytic reforming of organics and biomass. The fundamentals of such processes are here presented, together with the strategies which have been successfully adopted to improve the activity of TiO2-based photocatalysts, in particular for solar light exploitation, by addressing the key factors determining their efficiency for hydrogen generation. These include tailored light absorption by band gap engineering, charge separation improvement by means of junctions and the use of co-catalysts to facilitate electron transfer at the interface for both the reduction of protons and the concurrent oxidation reaction
KINETIC EFFECT OF RADIATION INTENSITY AND THERMAL AFTER-TREATMENT IN THE PHOTOPOLYMERIZATION OF DIALLYL OXYDIETHYLENE DICARBONATE
No full textThe influence of radiation intensity (from 1.08 × 10-7 to 2.48 × 10-4 einstein s-1 L-1) on the photopolymn. of diallyl oxydiethylene dicarbonate was investigated systematically not only in the initial stages of reaction, but also at high monomer conversion (x), in order to detect possible variations in the polymn. mechanism. In some of the runs irradn. was stopped at x = 0.55-0.65 and thermal after-treatments were carried out both in the presence and absence of air by following kinetically x-values during the self-decelerating crosslinking. To rationalize exptl. data a model is proposed which assumes two basically different mechanisms occurring simultaneously (bimol. termination and radical trapping), but with different "wts." as a function of time. Long living radicals produced by irradn. continue to react in the dark. The rate of this reaction, which is enhanced in the presence of O, is fitted by a relaxation model that considers double bonds, particularly of pendant groups, as traps, with increasing lifetimes, able to transfer to radical sites
Complex Power Distribution Network Investigation Using SPICE Based Extraction from First Principle Formulations
No full textThe modeling and the analysis of the power distribution networks (PDN) within multi-layer printed circuit board is crucial for the investigation of the performance of PCB systems. Carrying out such analyses in SPICE based tools has the advantage of being faster than the corresponding full-wave modeling and it allows obtaining both frequency and time domain results
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