323,119 research outputs found
Cooperative bene comune
No full textIl presente volume nasce con l’ambizioso obiettivo di comprendere come e perché l’impresa cooperativa costituisca uno strumento valido per la costruzione e la gestione condivisa dei beni comuni. Per raggiungere questo obiettivo, al volume hanno contribuito diciannove autori tra accademici e cooperatori. Il libro è composto da tre sezioni: ‘identità, valori ed obiettivi’, ‘buone pratiche e nuovi orizzonti cooperativi’ e ‘startup cooperative’. Come nel caso del ‘The Co-operator’ di King, che creò una guida pratica e teorica per i cooperatori del futuro, il volume aspira a riaprire un dialogo tra gli accademici, impegnati nello studio dell’impresa cooperativa, ed i cooperatori. Un dialogo all’insegna del bene comune
Pre-consolidation of decayed Angera columns with ammonium phosphate : a pilot study in a Milanese courtyard of XVI Century
No full textAngera stone is a lithotype widely employed in Lombardy (north Italy) for ornamental elements/frameworks of
historical buildings. Owing to decay processes it is affected by detachments, exfoliations, pulverizations with
consequent loss of material. The traditional application of synthetic organic products on the Angera surfaces had a
significant role in the decay processes as well (Colombo et al., 2006). Over the last years, the boundaries of
Conservation Science have been pushed toward the use of inorganic-mineral treatments that are stable, durable, highly
transpirable and more compatible with the stone substrates. Ammonium phosphate [DAP, (NH4)HPO4], one of the most
recent inorganic-mineral treatment, is based on the reaction between a water soluble precursor with carbonatic
substrates; the newly formed crystalline phases are able to restore the lost cohesion of the microstructure. Recent studies
investigated the interactions of DAP solutions with calcite of marbles and limestones (Matteini et al., 2011; Possenti et
al., 2016). To the best of our knowledge, no data are available on the application of DAP to: i) the conservation of
dolostones; ii) the pre-consolidation of decayed stones.
Therefore, in this study we explored the potentialities of DAP treatments as a pre-consolidating agent for white
Angera stone. DAP solutions were vaporized on vertical specimens to avoid mechanical contact with decayed surfaces.
The research evaluated the effects induced by the molarity and the application method (repeated applications, wetted or
dry substrate, comparison with paper poultice) on the surface and the influence of pre-consolidation on the subsequent
consolidation with DAP.
The formation of specific crystalline phases and their diffusion inside the first few microns of the stone matrix were
investigated following a multi-analytical approach (SEM-EDS, Raman and IR spectroscopies, XRD). The research
outcomes supplied outstanding indications for restoration, supporting the application of DAP pre-consolidating
treatments to Angera columns strongly decayed in a Milanese courtyard of XVI Century.
Colombo, C., Conti, C., Realini, M., Sansonetti, A. (2006): Diagnostic studies aimed to conservation works in S. Fedele church
(Milan). Proceedings of HWC Congress (Heritage, Weathering and Conservation), Taylor & Francis Group, 917-922.
Matteini, M., Rescic, S., Fratini, F., Botticelli, G. (2011): Ammonium phosphates as consolidating agents for carbonatic stone
materials used in architecture and cultural heritage: preliminary research. Int. J. Archit. Herit. Conserv. Anal. Restor., 5, 717-736.
Possenti, E., Colombo, C., Bersani, D., Bertasa, M., Botteon, A., Conti, C., Lottici, P.P., Realini, M. (2016): New insight on the
interaction of diammonium hydrogenphosphate conservation treatment with carbonatic substrates: a multi-analytical approach.
Microchem. J., 127, 79-86
Geoguard - An Innovative Technology Based on Low-cost GNSS Receivers to Monitor Surface Deformations
No full textThe study of reservoir behaviour is an important topic when dealing with the removal or the injection of fluids into the underground (e.g. hydrocarbon production or natural gas storage). The monitoring of surface deformations provides a valid contribution to the analysis of the reservoir. Nowadays the InSar technique is one of the most commonly used, providing a spatial distributed information, but also GNSS geodetic receivers are able to provide continuously superficial displacements. Recent experiments have shown the possibility to obtain results similar to those of dual frequency receivers also with cheap single frequency receivers. In this work we present GeoGuard, an innovative end-to-end service, for the continuous geodetic monitoring of critical infrastructure and natural hazards based on GNSS single frequency receivers. This innovative solution would allow in principle to monitor with a moderate price a large number of points and to retrieve continuously 3D superficial deformations with millimetric accuracy. The terminal unit, called GeoGuard Monitoring Unit, has been specifically designed to operate in challenging environments, an ad-hoc processing software to deals with single frequency GNSS receivers observations has been designed and implemented too. Some results on a real experiment are reported to show the achievable accuracies of the whole system
La mappa delle imprese cooperative in Italia
No full textIl capitolo è nato sotto una collaborazione, già avviata da tempo, tra l’Università degli Studi Roma Tre e l’Area Studi di Legacoop Nazionale. Il capitolo offre un quadro concettuale ed una mappatura delle imprese cooperative in Italia. L’obiettivo del capitolo è quindi fotografare e descrivere la distribuzione territoriale, temporale e settoriale, dell’universo cooperativo italiano nelle sue principali variabili economico-dimensionali e qualitative. Ulteriore scopo del capitolo è fornire una prospettiva di analisi sugli effetti futuri della recessione, sulla resilienza del movimento cooperativo e sul ruolo che esso sarà in grado di svolgere nell’azione di contrasto al declino industriale e occupazionale
Calcium phosphates crystallized on Carrara marble after phosphate-based consolidating treatment
No full textDiammonium hydrogen phosphate (DAP, (NH4)2HPO4) solutions have been introduced in the conservation field as a new inorganic-mineral treatments to consolidate or protect decayed carbonatic stone materials of historical monuments [1]. The treatment forms calcium phosphates through a dissolution and re-crystallization reaction, which takes place between hydrogen phosphate groups of the reagent and calcium ions of calcite of the substrate. Calcium phosphates nucleate on calcite grains with a pseudomorphic replacement reaction, and form a crystal network able to restore the lost cohesion of the microstructure. Despite the high number of studies on the crystallization of calcium phosphates and their formation on the surface of carbonatic substrates, only a few studies explored the formation of calcium phosphate phases on marbles treated with DAP and using calcite of the substrate as unique source for calcium ions [2-4]. Previous studies revealed a non-stoichiometric reaction that lead to the formation of a mixture of phases, each one characterized by different Ca/P molar ratio, solubility and stability [4]. In this study, we carry out a non-destructive synchrotron radiation grazing incidence X-ray diffraction (SR-GIXRD) investigation on DAP-treated marbles to determine how the mineralogical composition of the stone substrate affects the crystallization of stable and metastable calcium phosphates. The analyses were performed on Carrara marble specimens treated by capillarity by 0.76 M DAP solutions. Our results indicate that the presence of compositional micro-heterogeneity of Carrara marble favours the formation of specific phases. In general, the composition and the localization of the phases directly depend on the availability of free Ca2+ ions. Dicalcium phosphate dihydrate, a calcium phosphate with a low Ca/P molar ratio, is formed on carbonatic phases with a low Ca content, such as dolomite grains and Mg-containing veins. Octacalcium phosphate (OCP, Ca8(HPO4)2·5H2O) and poorly-crystalline partially-substituted hydroxyapatite (HAP, Ca5(PO4)3OH) are the foremost newly-formed phases when the substrate is mainly composed by calcite.
This study shed light on the potentialities of SR-GIXRD as a powerful non-destructive tool for the diagnostic of Cultural Heritage objects, since it allows investigating the conservation history of stone materials with an in depth evaluation of DAP consolidating processes [5].
[1] M. Matteini, S. Rescic, F. Fratini, G. Botticelli Int. J. Archit. Herit. Conserv. Anal. Restor. 2011, 5, 717.
[2] M. Kamiya, J. Hatta, E. Shimada, Y. Ikuma, M. Yoshimura, H. Monma Mater. Sci. Eng. B 2004, 111, 226.
[3] S. Naidu and G. W. Scherer J. Colloid Interface Sci. 2014, 435, 128.
[4] E. Possenti, C. Colombo, D. Bersani, M. Bertasa, A. Botteon, C. Conti, P. P. Lottici, M. Realini Microchem. J. 2016, 127, 79.
[5] E. Possenti, C. Colombo, C. Conti, L. Gigli, M. Merlini, J. R. Plaisier, M. Realini, G. D. Gatta Appl. Phys. A 2018, 124, 383
Precipitable Water Vapor Content from GNSS/GPS: Validation Against Radiometric Retrievals, Atmospheric Sounding and ECMWF Model Outputs over a Test Area in Milan
No full textThe availability of atmospheric water vapor content observations, with high temporal and spatial resolution, proved to have a high impact in the prediction of heavy rain events obtained from numerical weather prediction models. Several techniques can be applied to derive such observations. Some of them are well consolidated, some others are still under development. The focus of this work is to provide a statistical assessment of the consistency between four different techniques for water vapor monitoring, and specifically for precipitable water vapor (PWV) retrieval: radiometer-derived, European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological model derived, GNSS-derived and atmospheric sounding derived PWV. An overview of the data processing needed to estimate such parameter in the four cases is given to highlight how the corresponding PWV is related to the actual atmospheric water vapor content. Time series of PWV obtained with the different methods are compared for a case study in Milan, over a period of one year (March 1st, 2018–February 11th, 2019). A four-channel Ka-band/W-band radiometer located in the main campus of Politecnico di Milano is employed in association with a GNSS dual-frequency receiver (MILA), part of a regional network and installed in the same campus, 280 m far from the radiometer. GNSS data are processed by the goGPS software, applying a precise point positioning strategy. A comparison with atmospheric sounding (Milano-Linate station, located at about 6 km from the GNSS receiver), as well as with PWV derived from the ECWMF model (operational products), is also given. Results show a good agreement between the outputs of the four different data sources confirming GNSS as a valid alternative to the well consolidated techniques and opening the way to its synergistic use with co-located radiometers
Experimental study on low-cost satellite-based geodetic monitoring over short baselines
No full textThe use of geodetic techniques, in particular of the global positioning system (GPS), or other global navigation satellite systems (GNSS), for monitoring different kinds of deformations is a common practice. This is typically performed by setting a network of geodetic GPS/GNSS receivers, allowing accuracies in the order of millimeters. The use of lower-cost devices has been recently studied, showing that good results can be achieved. In this paper, the impact of the software used for the data analysis is also investigated to verify whether a fully low-cost monitoring system, i.e., both hardware and software, can be set up. This is done by performing a series of relative positioning experiments in which data are processed by different software packages. The main result is that by using a low-cost u-blox EVK-6T GPS receiver and analyzing its data with free and open-source software, movements of the order of a few millimeters can be detected when a short baseline with daily solutions is used
Chirurgia orale in pazienti trattati con anticoagulanti: valutazione di un protocollo operativo
No full textValutazione con tecnica di analisi digitale di fotografie cliniche in pazienti trattati per LPO erosivo
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