120,346 research outputs found
Guide archeologiche. Preistoria e Protostoria in Italia. Emilia Romagna
No full textQuesto volume, che fa parte della "collana Guide Archeologiche. Preistoria e Protostoria in Italia", è dedicato all'Emilia Romagna presentandone i più importanti musei e siti archeologic
Centenario del Quartiere Prati - Della Vittoria: Lezione di storia tra il prof. Luca Ribichini è il Rettore dell'Università Lumsa, Giuseppe Dalla Torre
No full textLa manifestazione prendeva spunto dalle innovazioni che Roma Capitale aveva Messo in atto subito subito dopo il 1911. Uno scambio di idee tra il prof Luca Ribichini ed il Magnifico Rettore LUMSA Giuseppe Della Torre.CENTENARIO del QUARTIERE PRATI - DELLA VITTORIA
Il Municipio ROMA XVII promuove un calendario di eventi, progetti e iniziative associate al "Centenario Prati-Della Vittoria" in conformità a quanto disposto dal Consiglio del Municipio con deliberazione n. 39 del 21 ottobre 2010. Nel 2011, difatti, ricorrono i 100 anni dell'Esposizione Universale del 1911, a seguito della quale la vecchia Piazza d'Armi divenne spazio espositivo, ponendo contestualmente le basi del nuovo quartiere denominato successivamente "Della Vittoria". L'evento è rilevante, e merita una celebrazione specifica, di cui il Municipio Roma XVII si fa promotore, in collaborazione col Dipartimento di Rilievo, Analisi e Disegno dell'Ambiente e dell'Architettura dell'Università "La Sapienza" di Roma.
A cento anni da quella data, il quartiere festeggia il suo anniversario.
Per tutta la giornata, dalla mattina alla sera si alterneranno le lezioni di storia del professore Luca Ribichini della Sapienza e di Giuseppe Dalla Torre rettore della Lumsa, visite guidate, concerti elaborati sugli spartiti del tempo raccolti dall'editore Stefano De Luca nel volume Prati 1911, recital su testi risorgimental
Resilienza di comunità: una rassegna
No full textNelle scienze umane e sociali il concetto di resilienza ha una storia piuttosto
recente data la dominanza di un modello patocentrico che ha sempre
postulato l’equazione rischio-disadattamento. Il livello di analisi prevalente
negli studi sulla resilienza è quello individuale attraverso il quale la resilienza
è definita come la capacità di superare e uscire rinforzati dalle difficoltà
della vita (Putton e Fortugno, 2006). In questo senso resilienza può
avere una duplice accezione, come esito e come processo. La resilienza
come esito denota un risultato di adattamento in seguito all’esposizione a
fattori di rischio, una capacità di mantenere un certo equilibrio nel funzionamento,
al di là di possibili cadute momentanee, in seguito a eventi perturbanti.
La resilienza come processo indica, invece, la molteplicità di fattori,
collocati sul piano individuale, sociale e ambientale che permettono di
raggiungere un esito di adattamento positivo (Prati, 2008).
Gold or silver-decorated multiwalled carbon nanotubes modified electrodes for trace electroanalysis
No full textTrace analysis [1] (i.e. the analysis of analytes in concentration low enough to cause difficulty, generally under 1 ppm) albeit very challenging, in the last years has shown a tremendous growth, prompted by the urgent need of many International Organizations (US Environmental Protection Agency EPA, U.S. Food and Drug Administration FDA, European Food Safety Authority EFSA, World Health Organization WHO) looking for new analytical techniques for the detection of different molecules in different and increasingly more complex matrixes.
The determination of trace analytes requires reliable and robust analytical methods characterized by high level of sensitivity, precision, accuracy, selectivity and specificity. Among different analytical techniques electroanalytical ones and particularly those based on pulsed voltammetry, seem to be a promising independent alternative in terms of very high precision, accuracy and sensitivity. Advantages in using these latter systems lie on simplicity of use, portability, easy automation and possibility of on-line and on-site monitoring without sample pre-treatments and low costs.
In this context, the use of nanosized and/or nanostructured materials for the modification of electrodes is growing in importance, with the aim of increasing the affinity for the analyte, increasing sensitivity, lowering the limits of detection and minimizing or completely avoiding interferences, i.e. increasing their selectivity. Carbon nanomaterials coupled with metal nanoparticles [2, 3] present unique peculiar properties, dependent on metal nanoparticle size and shape and therefore are extensively employed in electroanalysis as tunable materials.
In this communication, we will present the electrochemical characterization (by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy) and the electroanalytical application of modified electrodes based on carbon nanotubes decorated with gold or silver nanoparticles. In particular, the synergic effect of both metal and carbon nanomaterials was investigated. Moreover, the use of PVA protective polymer for metal NPs allows better electroanalytical performances due to the protection from oxidation, fouling products and interferences. The optimized electrodes were then tested for the determination of relevant or toxic analytical substances for environmental monitoring such as glycerol and chlorinated compounds, with interesting results [4].
[1] D.T. Pierce, J.X. Zhao, Trace Analysis with Nanomaterials, Wiley-VCH, Weinheim (Germany), (2010).
[2] L. Rassaei, M. Amiri, C.M. Cirtiu, M. Sillanpaa, F. Marken, M. Sillanpaa, Trends in Analytical Chemistry 30(11) (2011) 1705-1715.
[3] V. Pifferi, V. Marona, M. Longhi, L. Falciola, Electrochimica Acta 109 (2013) 447-453.
[4] V. Pifferi, G. Facchinetti, A. Villa, L. Prati, L. Falciola, Catalysis Today, (2014), in press, doi:10.1016/j.cattod.2014.10.00
Multiwalled carbon nanotubes decorated with gold or silver nanoparticles for trace electroanalysis
No full textAlbeit very challenging, in the last years trace analysis (Pierce and Zhao, 2010) (i.e. the analysis of analytes in concentration low enough to cause difficulty, generally under 1 ppm) has shown a tremendous growth, prompted by the urgent need of many International Organizations (US Environmental Protection Agency EPA, U.S. Food and Drug Administration FDA, European Food Safety Authority EFSA, World Health Organization WHO) looking for new analytical techniques for the detection of different molecules in different and increasingly more complex matrixes.
Trace analytes determination requires reliable and robust analytical methodologies characterized by high level of sensitivity, accuracy (in terms of precision and trueness), selectivity and specificity. In this context, electroanalytical techniques, particularly those based on pulsed voltammetry with modified electrodes, seem to be a promising independent alternative, combining the previously sought properties with other important characteristics: simplicity of use, low costs, portability, easy automation and possibility of on-line and on-site monitoring without tedious sample pre-treatments.
Among different possible modifying materials, nanosized and/or nanostructured materials are growing in importance and use, with the aim of increasing the affinity for the analyte and the sensitivity, lowering the limits of detection and minimizing or completely avoiding interferences, increasing the selectivity. In this field, unique peculiar properties dependent on metal nanoparticle size and shape are demonstrated by carbon nanomaterials coupled with metal nanoparticles (Rassaei et al., 2011 and Pifferi et al., 2013). For this reason, these materials are now extensively employed in electroanalysis for electrode modification.
In this framework, the electroanalytical application of modified electrodes based on carbon nanotubes decorated with gold or silver nanoparticles are here presented. The modified electrode were previously electrochemically characterized (by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy). In particular, the synergic effect of both metal and carbon nanomaterials was investigated. Moreover, the use of PVA as protective polymer for metal NPs, has demonstrated its role in enhancing the electroanalytical performances due to the protection from oxidation, fouling products and interferences.
The optimized electrodes were finally tested for the determination of relevant or toxic analytical substances for environmental monitoring such as glycerol and chlorinated compounds, with interesting results (Pifferi et al., 2014).
Pierce D.T., Zhao J.X. (2010). “Trace Analysis with Nanomaterials” Wiley-VCH, Weinheim.
Pifferi V., Facchinetti G., Villa A., Prati L., Falciola L. (2014). Electrocatalytic activity of multiwalled carbon nanotubes decorated by silver nanoparticles for the detection of halothane. Catalysis Today, in press.
Pifferi V., Marona V., Longhi M., Falciola L. (2013). Characterization of polymer stabilized silver nanoparticles modified glassy carbon electrodes for electroanalytical applications. Electrochimica Acta, 109, 447-453.
Rassaei L., Marken F., Sillanpaa M., Amiri M., Cirtiu C.M., Sillanpaa M. (2011). Nanoparticles in electrochemical sensors for environmental monitoring. Trends in Analytical Chemistry, 30(11), 1704-1715
Interventi per l'età adolescenziale e giovanile. Bullismo e omofobia.
No full textIl bullismo omofobico riguarda tutti quegli atti di prepotenza e abuso che si
fondano sull’omofobia e che sono rivolti a persone percepite come omosessuali o
atipiche rispetto al ruolo di genere. È un fenomeno basato su una matrice omofobica,
ovvero sull’idea che l’omosessualità sia una caratteristica indesiderabile e
negativa (Pietrantoni e Prati 2011)
Electrochemical characterization of Au/Pd catalysts
No full textGold-based catalysts have attracted more and more interest in recent years due to their peculiar activity in catalytic reactions, such as low-temperature oxidation of CO, hydrochlorination of alkyne, liquid phase oxidation of alcohols and polyols [1]. However, concerning selective liquid phase oxidation, despite the peculiar selectivity shown, gold catalysts suffer from a severe limitation consisting in the use of a basic environment. This drawback has a strong impact on the use of gold and promoted the evolution of monometallic into bimetallic systems.
In the present work, an electrochemical characterization of homemade Au/Pd bimetallic catalysts is performed. Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) demonstrate the presence of an electronic interaction between the two metals providing a strong support in the determination of the nature of the synergy between Au and Pd in the liquid phase oxidation of alcohols [2].
Fig.1 shows the voltammetric patterns, recorded in 0.1M H2SO4, for Au, Pd and alloyed Au/Pd nanoparticles deposited for drop casting on a glassy carbon electrode (GC) used as inert support. The nanoalloy presents a larger oxidation peak due to the oxidation of the alloy, which comprises the two oxidation peaks of the single metals, while the reduction peak (at 0.63V) has an intermediate behaviour between Au and Pd. This behaviour indicates that the oxide formed on the alloy is more stable with respect to the gold one but it is really less stable than the palladium one. Charge transfer resistance (RCT) obtained from impedance data are in the order Pd > Alloy >> Au, confirming the intermediate behaviour shown in the voltammetric characterization.
Correlating these results to the catalytic behaviour observed in the glycerol selective oxidation of Pd, Au and AuPd catalysts we can conclude that the activities of the different systems seems to be connected not only to the redox behavior. In fact, the higher activity of the AuPd bimetallic system in the liquid phase oxidation of glycerol seems to be due to a compromise between the stability of the oxidic species (decreased with respect to Pd) and the facility of hydride formation (increased with respect to Au).
References
[1] L. Prati, A. Villa, Gold Catalysis: Preparation, Characterization and Applications, Pan Stanford Publishing Pte. Ltd.: Singapore City, Singapore, (2015).
[2] V. Pifferi, C. Chan-Thaw, S. Campisi, A. Testolin, A. Villa, L. Falciola and L. Prati, Molecules, 21, (2016), 261
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