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Ag nanoaggregates as efficient broadband sensitizers for Tb 3+ ions in silica-zirconia ion-exchanged sol-gel glasses and glass-ceramics
No full textIn this paper we report the study of down-shifting silica-zirconia glass and glass-ceramic films doped by Tb3+
ions and Ag nanoaggregates, which combine the typical spectral properties of the rare-earth-ions with the
broadband sensitizing effect of the metal nanostructures. Na-Tb co-doped silica-zirconia samples were obtained
by a modified sol-gel route. Dip-coating deposition followed by annealing for solvent evaporation and matrix
densification were repeated several times, obtaining a homogeneous crack-free film. A final treatment at 700 °C
or 1000 °C was performed to control the nanoscale structural properties of the samples, resulting respectively in
a glass (G) or a glass-ceramic (GC), where tetragonal zirconia nanocrystals are surrounded by an amorphous
silica matrix. Ag introduction was then achieved by ion-exchange in a molten salt bath, followed by annealing in
air to control the migration and aggregation of the metal ions. The comparison of the structural, compositional
and optical properties are presented for G and GC samples, providing evidence of highly efficient photoluminescence
enhancement in both systems, slightly better in G than in GC samples, with a remarkable increase
of the green Tb3+ PL emission at 330 nm excitation: 12 times for G and 8 times for GC samples. Furthermore,
after Ag-exchange, the shape of Tb3+ excitation resembles the one of Ag ions/nanoaggregates, with a broad
significant absorption in the whole UV-blue spectral region. This broadband enhanced downshifting could find
potential applications in lighting devices and in PV solar cells
Alessandro Magno e gli alberi oracolari in un ciclo di pitture valdostane del XIII secolo
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Sedimentary and morphological features of a very shallow river delta: integration of high resolution multibeam bathymetry and satellite images of Po di Pila Delta (Italy)
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Filosofia delle emozioni
No full textL’orizzonte valoriale dischiuso dalla conoscenza affettiva è un importante ambito di ricerca per l’epistemologia, l’etica, la politica e la teologia. Le emozioni contribuiscono alla definizione del valore dell’oggetto al quale si riferiscono ed esprimono l’orizzonte di significato all’interno del quale il soggetto che sente, pensa e agisce costituisce la propria identità in relazione con il mondo. Le emozioni svolgono un ruolo centrale nella creazione di giudizi di valore e hanno la capacità di attivare processi motivazionali, in quanto sono inserite in una costellazione di funzioni conoscitive, dall’immaginazione all’aspirazione, dal sentire corporeo alla deliberazione
A born-translated fairy tale: transcultural readership and anti-exoticism in Robert Louis Stevenson’s “The Bottle Imp”
No full textThe six years Robert Louis Stevenson spent in the Pacific region offer a particularly stark contrast with his received image as an uncommitted romancer (and hence, in the context of British colonialism, as a tacit supporter of imperialism). His Pacific writings are the work of a powerfully realist writer, with strong interests in ethnography and local history, engaged in the political life of the region, and an active supporter of the native populations in their opposition to imperial rule. In this article I focus on "The Bottle Imp", a short story that, at first sight, constitutes a less confrontational, more accommodating literary project if compared with most of Stevenson's production on the Pacific. However, not only does this text encapsulate several elements of the poetics that characterize Stevenson's Pacific writing, but it is also the only work of Stevenson's career to be conceived for a Polynesian audience, which adds a significant layer of complexity to its analysis. I argue that with this work Stevenson creates a "born-translated" fairy tale, which results in the adoption of specific narrative techniques and in a particular declination of Stevenson's political agenda and anti-exoticist strategies. This, in turn, means to frame "The Bottle Imp" within some of the current debates on the global circulation of literature and its effect on the politics, ethics and aesthetics of literary texts