1,720,972 research outputs found
Applicazione della diffrazione a dispersione di energia allo studio della cinetica di transizione di fase in campioni polimerici : tesi di dottorato di ricerca in scienza dei materiali
No full textFirst measurements by the EDXD-PT technique of the effect of the melting time on polymer crystallisation kinetics
No full textA nonconventional energy-dispersive X-ray diffraction method applied to phase transitions (EDXD-PT) was used to measure polymer crystallization rates. It enables one to follow the kinetics of phase transitions by a direct comparison of diffraction patterns collected during the process and suitably normalized with respect to X-ray absorption spectra taken with the same time scan. With this technique, the memory that a polymer retains of its thermal history is investigated by correlating the crystallization rates to the residence time in the melt
Superhard rhenium diboride films: Preparation and characterization
No full textRecently, the superhardness of rhenium diboride was discovered. This study presents a first successful preparation and characterization of thin ReB(2) films. The films were deposited by the pulsed laser deposition (PLD) technique. The morphology, microstructure, and hardness of the films were investigated. The films are compact and continuous, with a preferred (002) orientation. The composite Vickers hardness of the film-substrate systems was measured, and the intrinsic hardness of the films was separated using an area law-of-mixtures approach taking into account the indentation size effect. The obtained films are found to be superhard: the intrinsic film hardness value (52 GPa) is close to that of the ReB2 bulk
Nanoscale in situ morphological study of proteins immobilized on gold thin films
No full textThe nanoscale organization of acetylcholinesterase (AChE) and of its polyclonal antibody immobilized on gold thin films was studied by means of Energy Dispersive X-ray Reflectometry (EDXR) and Atomic Force Microscopy (AFM). The macromolecules were alternatively deposited over a self-assembled monolayer (SAM) of N-hydroxysuccinimide esters of thioctic acid. The measurements, collected in situ at subsequent deposition stages of the device, gave information on the distribution of the macromolecules on the surface showing that both the proteins can bind covalently to the SAM. In addition to this, we demonstrated that the antigen-antibody reaction takes place when one of the two reactants is anchored to the surface. © 2009 American Chemical Society
Gas sensing (RuPc)(2) thin films: Electrical response to NO2 gas and morphological changes induced by external moisture
No full textThe morphological changes induced in (RuPc)(2) gas sensing thin films by hydration and de-hydration processes were investigated. Prior to this study a preliminary characterization was performed by conductivity measurements upon exposure to NO2 gas fluxes, to verify the electrical sensing response of the films. This response was correlated to the bulk morphological modification of the films. Subsequently, the effect of external moisture on the morphological stability of the films was addressed. This morphological characterization of the films was performed by using the energy dispersive X-ray reflectivity (EDXR) and atomic force microscopy (AFM) techniques, both ex situ and in situ, i.e. under operating conditions, during exposure of these films to 100% of relative humidity. The measurements allowed an accurate observation of both the surface morphology(i.e. its roughness obtained independently by EDXR and AFM). Moreover bulk evolution of the films was obtained by in situ EDXR and the morphological changes allowed to retrieve information on the water uptake dynamics. Moreover, the reversibility of the water/film interaction was studied and correlated to the sensing properties of the (RuPc)(2). (C) 2008 Elsevier B.V. All rights reserved
Superhard Properties of Rhodium and Iridium Boride Films
No full textVery recently, the superhard properties of rhenium and ruthenium boride films were reported, this research being inspired by the discovery of the ReB(2) bulk superhardness. in this paper, we report the first successful deposition and characterization of rhodium and iridium boride films, other possible candidates for superhard materials. The films were prepared, applying the pulsed laser deposition technique, and studied by X-ray diffraction, scanning electron and atomic force microscopies, and Vickers microhardness. The refined structural parameters for RhB(1.1) and IrB(1.1) films were obtained. The RhB(1.1) film is characterized by the submicrometer crystallite size, whereas for the IrB(1.1) film, the crystallite size is in the tens of nanometers range, and this latter film presents a slightly preferred orientation along the [004] direction, Both the films exhibit very similar morphology, being composed of dense globular aggregate texture. The RhB(1.1) film presents a homogeneously textured surface with an average roughness of 20-50 nm, whereas the IrB(1.1) film possesses a finer texture with an average roughness OF 20-30 nm. The intrinsic hardness of both films lies in the superhardness range: the 1.0 mu m thick RhB(1.1) him possesses a hardness of 44 GPa, whereas the 0.4 mu m thick IrB(1.1) film has a hardness of 43 GPa
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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