83 research outputs found
Sartre e il cinematografo
The article investigates the relationship between French philosopher Jean Paul Sartre and the cinema, with the aim of investigating the different aspects of this elaborate connection. The piece examines and finds Sartre’s philosophical richness in his early works, where he shows his fascination for the tremendous expressiveness of the cinematographic medium. The article crosses also the boundaries of Sartre’s phenomenological analysis of the image condition, without forgetting his following work as author of screenplays, as an important experience that inspired Sartre to change his point of view on the cinema itself. KEYWORDS: movie; flux; screenplay; imag
Thermal boundary resistance from transient nanocalorimetry: a multiscale modeling approach
The Thermal Boundary Resistance at the interface between a nanosized Al film
and an Al_{2}O_{3} substrate is investigated at an atomistic level. A room
temperature value of 1.4 m^{2}K/GW is found. The thermal dynamics occurring in
time-resolved thermo-reflectance experiments is then modelled via macro-physics
equations upon insertion of the materials parameters obtained from atomistic
simulations. Electrons and phonons non-equilibrium and spatio-temporal
temperatures inhomo- geneities are found to persist up to the nanosecond time
scale. These results question the validity of the commonly adopted lumped
thermal capacitance model in interpreting transient nanocalorimetry
experiments. The strategy adopted in the literature to extract the Thermal
Boundary Resistance from transient reflectivity traces is revised at the light
of the present findings. The results are of relevance beyond the specific
system, the physical picture being general and readily extendable to other
heterojunctions.Comment: 12 pages, 8 figure
Growing CeO Nanoparticles within the Nano-Porous Architecture of the SiO Aerogel
In this study, new CeO-SiO aerogel nanocomposites obtained by controlled growth of CeO nanoparticles within the highly porous matrix of a SiO aerogel are presented. The nanocomposites have been synthesized via a sol-gel route, employing cerium (III) nitrate as the CeO precursor and selected capping agents to control the growth of the CeO nanoparticles, which occurs during the supercritical drying of the aerogels. Samples with different loading of the CeO dispersed phase, ranging from 5 to 15%, were obtained. The nanocomposites showed the morphological features typical of the SiO aerogels such as open mesoporosity with surface area values up to 430 m·g. TEM and XRD characterizations show that nanocrystals of the dispersed CeO nanophase grow within the aerogel already during the supercritical drying process, with particle sizes in the range of 3 to 5 nm. TEM in particular shows that the CeO nanoparticles are well distributed within the aerogel matrix. We also demonstrate the stability of the nanocomposites under high temperature conditions, performing thermal treatments in air at 450 and 900°C. Interestingly, the CeO nanoparticles undergo a very limited crystal growth, with sizes up to only 7 nm in the case of the sample subjected to a 900°C treatment
The holographic QCD axion
A holographic model of QCD axion is presented. It describes a composite axion in the KSVZ class. Having a gravity dual, based on the Witten-Sakai-Sugimoto model, it is calculable in the strongly coupled regime. Its basic properties are derived, including the low energy Lagrangian, from which the axion couplings to nucleons can be derived. Basic features in the deconfined phase are studied as well. In particular, the temperature dependence of the axion mass is extracted from the topological susceptibility. As an aside, the topological susceptibility of strongly coupled N = 4 SYM at finite temperature is derived for the first time.Fil: Bigazzi, Francesco. Istituto Nazionale di Fisica Nucleare. Sezione di Firenze; ItaliaFil: Caddeo, Alessio. Istituto Nazionale di Fisica Nucleare. Sezione di Firenze; Italia. Università degli Studi di Firenze; ItaliaFil: Cotrone, Aldo L.. Istituto Nazionale di Fisica Nucleare. Sezione di Firenze; Italia. Università degli Studi di Firenze; ItaliaFil: Di Vecchia, Paolo. Universidad de Copenhagen; Dinamarca. Royal Institute of Technology; SueciaFil: Marzolla, Andrea. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Comisión Nacional de EnergÃa Atómica. Centro Atómico Bariloche; Argentina. Istituto Nazionale di Fisica Nucleare. Sezione di Firenze; Italia. Università degli Studi di Firenze; Itali
Tuning the Properties of Nanoceria by Applying Force: Stress Induced Ostwald Ripening
The ionic conductivity and activity of a material, such as ceria, is central to its exploitation in applications such as fuel cells or catalysis. Grain Boundaries (GB) influence profoundly the ionic conductivity and activity of a material. Accordingly, the ability to control GB concentrations is pivotal to these applications. Here, we show that Oswald ripening can be induced by applying uniaxial force. In particular, grain-boundaries are purged to facilitate single nanocrystals from polycrystalline precursors. Our simulations thus predict mechanisms for strain-tunable properties
Gold Thione Complexes
The reaction of the ligand Et4todit (4,5,6,7-Tetrathiocino-[1,2-b:3,4-b']-diimidazolyl-1,3,8,10-tetraethyl-2,9-dithione) with gold complexes leads to the dinuclear gold(I) complexes [{Au(C6F5)}2(Et4todit)] and [Au(Et4todit)]2(OTf)2, which do not contain any gold-gold interactions, or to the gold(III) derivative [{Au(C6F5)3}2(Et4todit)]. The cristal structures have been established by X-ray diffraction studies and show that the gold centers coordinate to the sulfur atoms of the imidazoline-2-thione groups
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