186,459 research outputs found
Un'amministrazione imprenditoriale ? Il cambiamento nel sistema pubblico tra apprendimento e ipocrisia
No full textUn'analisi esplorativa sulle dinamiche organizzative
No full textIl capitolo esamina i nessi fra assetti organizzativi, culture e competenze professionali dei ricercatori del CNR
"Adesione al trattamento e dimensioni psicologiche nel diabete". IX Congresso Nazionale della Società Italiana di Psicologia della Salute. Bergamo, 23-25 Settembre 2010.
No full textAquifer-type behaviour of Marnoso-Arenacea formation in Northern Apennines: evidences from hydrogeological monitoring and hydrochemical data
No full textPetrology of the prehistoric lavas and dyke of the Barren Island, Andaman Sea, Indian ocean
No full textAlthough Barren Island (Andaman Sea, Indian Ocean) witnessed several volcanic eruptions during historic times, the eruptions that led to the formation of this volcanic island occurred mainly during prehistoric times. It is still active and currently in the fumarolic stage. Its volcanic evolution appears to be characterized by a constructive phase with the piling up of lava flows and scoria deposits and Strombolian activities, followed by a sudden collapse of the main cone. Deposits of a possible caldera-forming eruption were not recognized earlier. After a period of peri-calderic hydromagmatic activity, whose deposits presently mantle inner and outer caldera walls, a new phase of intra-calderic Vulcanian activities took place. A prominent dyke in the SE inner side of the caldera wall was recognized. Petrographically the lava flows and dyke are similar but they differ in their chemical composition (viz., SiO2, MgO, Ni, Cr) significantly. Similarity in major, minor and trace element composition (viz., K/La, K/Nb, K/Rb, K/Ti ratios) of these rocks together with Chondrite normalized trace element (Rb, Ba, Sr, P, Zr, Ti and Nb) and REE (La, Ce, Nd and Y) patterns of the Barren Island prehistoric lava flows and dyke and low-K lavas of Sunda Arc indicates that Barren Island must have evolved from a source similar to that of Sunda Arc lavas during the Quaternary Period
Polydeformed structures of the central Apuane Alps between Arni and Mt. Corchia: Historical knowledges, structural data and open problems [La struttura polideformata delle Alpi apuane centrali tra Arni e M. Corchia: conoscenze storiche, dati attuali e problemi aperti]
No full textThis contribution concerns the puzzling polydeformed structure cropping out in the Arni-Mt Corchia area and surroundings, in the central-eastern Apuane Alps Metamorphic Complex (AMC). The main point is the presence of thick and long belts of principally Mesozoic and Tertiary paraschists (Apuane Unit) exhibiting widespread milonitic and/or cataclastic-milonitic meso- to microfabrics. In the frame of the AMC large-scale structure, characterised by a general Apennine strike of all the tectonic lineaments, these belts are persistent mainly along a 5-6 km wide, WSW-ENE trending length from the high Frigido valley (Massa) up to E of Isola Santa village, in the Turrite Secca valley, a transversal setting well known since the work of GIGLIA (1967). These structures resulted from extreme development of localised shear deformation during the last stages of the compressive tectonic phase of the Tertiary orogenesis, being clearly involved in polystage D 2 deformations. The recognition and detailed mapping of such shear pattern allows to highlight further aspects in the progressive deformation of the compression tectonics (D 1) and the following uplift-related extension (D 2) in the lowermost metamorphic unit directly visible in the Apennine chain
Effect of electron velocity distribution on the heating of core by corona in a spherical pellet
No full textSANS/VSANS investigation of the porosity microstructure in rocks from a natural CO2 reservoir
No full textSequestration of CO2 in deep geological reservoirs represents one of the potential methods to reduce anthropogenic emissions into the atmosphere. In the long term the injected CO2 dissolves into the local formation of rocks and, when present, in saline deep aquifers, participating to a variety of geochemical reactions. The overall impact of these processes produces changes in mineralogy, texture, permeability and porous structure of the rocks, to a level which depends on the different lithologies present in the rocks.
Mineralogical changes can be investigated by considering what occurs in rocks and minerals with natural CO2 accumulations, as analogues for geological sequestration. Also computer simulations, based on thermodynamics, kinetics and geochemical modeling [1, 2], can be beneficial. On the other hand, reliable data concerning the porous structure, which is so important to trap CO2, can be hardly extracted from computer simulations.
In this context a valuable help can be provided by Small and Very Small Angle Neutron Scattering techniques (SANS and VSANS, respectively): they have been indeed demonstrated to be powerful tools for the determination of the microstructure and porosity of rocks from Ångstrom to millimeter sizes [3], proofing also the existence of fractal dimensions for the volume and surfaces interfaces between pores and rocks.
Here we present the preliminary results of a SANS/VSANS investigation on rocks pertaining to a geological context (located in Eastern Tuscany, Central Italy) featured by a deep geological gas reservoir. The former reservoir was intercepted by a bore-well drilled in ’80 by ENI and is presently hosting 700 bar of supercritical CO2. Texture and mineralogy of volcanic rocks samples, from drill cores corresponding to the top of the reservoir, were found to be heavily modified by the interaction with CO2-rich fluids.
The combined neutron experiments, performed using the PAXE and G5bis diffractometers at LLB (Saclay, F), allowed to approximately investigate pore sizes ranging from ∼ 60 nm to ∼ 6 μm. Samples of host rocks (from drill core) and a selection of possible analogues of the same volcanic rocks, unaffected by CO2 presence, were chosen for the experiments together with samples of rocks, from outcrops, corresponding to the geological layers the characteristics of geological layers overlying the reservoir. Globally these rocks are representative of a wide spectrum of different lithologies (as limestones, marls, evaporitic deposits bearing gypsum and volcanic rocks with intermediate-acid composition).
The information provided by these experiments must still be fully analyzed and integrated with other data (e.g. chemical composition of rocks and fluids [4]) in order to get a better understanding of: i) the role and the possible effects of CO2 in determining the micro-porosity of these host rocks, and ii) the sealing effect of the sedimentary rocks overlying the reservoir which act as a barrier with respect to the CO2-rich gases.
References
[1] Zhu C. and Anderson G., 2002 Environmental Applications of Geochemical Modeling, Cambridge University Press, Cambridge, UK, 284 pp.
[2] Cantucci B, Montegrossi G., Vaselli O., Tassi F., Quattrocchi F., and Perkins E.H., 2009 Geochemical modelling of CO2 storage in deep reservoirs: The Weyburn Project (Canada) case study. Chemical Geology, 265 (1), 181-197.
[3] A.P. Radlinski, 2006 and reference therein, in Neutron Scattering in Earth Sciences, Reviews in Mineralogy & Geochemistry, 63, pp. 363-397.
[4] Bicocchi G., Montegrossi G., Ruggieri G., Buccianti A. and Vaselli O. (2011). Modeling composition of Ca-Fe-Mg carbonates in a natural CO2 reservoir. In: Egozcue, J.J., Tolosana-Delgado, R. and Ortego, M.I. (eds.). Codawork11 Proceedings, 16 p
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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