1,720,964 research outputs found
Multilayer adsorption of gases in solids
No full textAdsorption phenomena of gas in solids are investigated using the Ono-Kondo lattice model. Layer concentrations rho(n) (n = 1, 2,... L) and Gibbs adsorption Gamma are presented versus the bulk density rho(b) and temperature. It is found that the density in core region (inner layers) and the density of the first layers next to the walls exhibit an opposite temperature dependence: while the density near the walls increases with decreasing temperature the density of the core region decreases to reach rho(b) as T increases. The density profile of the layers is also presented
Three state lattice-gas model for two-component gas adsorption in solids
No full textA molecular field method is used to study a spin-one Ising (lattice-gas) model appropriate for the multilayer adsorption of a two-component gas. The model is used in its simplest form to discribe the phase transition and coadsorption isotherms of the mixture. We found that the phase transition occurs in a narrow interval of the total coverage. The adsorption isotherms depend on the chemical potentials of both components and on the temperature. The density profiles of both components are also presented
Hydrogen desorption from magnesium hydride - graphite nanocomposites produced by ball milling
No full textAbstract
Magnesium hydride–graphite composites produced via ball milling exhibit fast H2 desorption/absorption kinetics; moreover, their activation behaviour is particularly attractive if compared with MgH2-based materials obtained so far. In this work, we report the phase analysis (by X-ray diffraction) and investigate the crystal structure and the desorption behaviour (using a home-made Sievert apparatus) of MgH2–graphite composites produced by ball milling. Milling with graphite is found to improve the desorption rate of MgH2 changing the reaction mechanism
Coadsorption isotherms of multilayer adsorbates with lateral interactions
No full textAbstract
Multilayer lattice–gas model which accounts for lateral interactions between adsorbed molecules is used in the frame of the mean field approach to describe coadsorption phenomena and phase transition in multilayered lattice. The differential ratio which measure the strength of the adsorption is represented. We find that the phase transition occurs at high enough attractive interactions between adsorbed species and the shape of the isotherms depends strongly on the chemical potential of both components and on the strength of the lateral interactions
Idruri metallici nanocristallini per immagazzinamento di idrogeno: compositi a base Mg prodotti tramite macinazione ad alta energia di polveri
No full text(Articolo su invito
Structural evolution of the amorphous grain boundary phase during nanocrystallisation of Fe72 Cu1Nb4.5Si13.5B9
No full textThe structure of the amorphous grain boundary phase during progressive stages of nanocrystallisation in the Fe72Cu1Nb4.5Si13.5B9 alloy has been followed using XRD, SAXS and Mossbauer spectroscopy. The initial compositional inhomogeneity sets-in with increasing crystallisation, as a result of the depletion in Fe of the amorphous phase, which partly homogenises for longer annealing times due to long-range diffusion
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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