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Il metodo Rietveld nello studio della capacità deflocculante di tripolifosfati di sodio
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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
Sintering behaviors of two porcelainized stoneware compositions using pegmatite and nepheline syenite minerals
No full textSemi-vitreous bodies, with flexural strength of ~78 MPa and water absorption of ~0.4 % for the optimal maturated specimens, were successfully prepared with solid solutions of pegmatite and nepheline syenite, respectively, for the full dense (P) and relatively porous composition (G). Despite the similarity on the bulk chemical composition of the two formulations, it was found that their thermal behaviors were significantly affected by the action of CaO on the flux system considered leading to earlier vitrification of P specimens with high flexural strength as from 1,175 C. Conversely, the flexural strength of G specimens increases progressively with soaking time and temperature development up to 1,225 C. The positive action of 5 mass% of CaO in the vitrification range of pegmatite solution, the relative low temperature of maturation of the semi-vitreous matrices, and the results of water absorption allow us to describe the formulations studied to offer promising potential in the production of sustainable and low-cost porcelainized stoneware. The high strength of P at relatively low temperature could be explained by the matrix-strengthening theory, while the extent of crystallization of G could be ascribed to the mullite theory. © 2013 Akadémiai Kiadó, Budapest, Hungary
Self-assembling organogelators for artificial stratum corneum models: key-role parameters in skin permeation prediction
No full textThe development of in vitro methods to predict in vivo percutaneous absorption of bioactive molecules is a challenge to which the researchers are called in order to eliminate or reduce the pharmacological and toxicological tests on animal models. Artificial stratum corneum (SC) models obtained by self-assembled oganogelators were designed for skin permeation assessment of butyl methoxydibenzoylmethane (BMDBM, log Po/w = 4.68) and methylene blue (MB, log Po/w = 0.91). A multi-analytical approach was adopted to provide detailed understanding about the gelator organization within the models and find possible parameters playing a key-role in in vivo and ex vivo SC permeation prediction. The evaluation of in vitro skin permeation data compared with those obtained ex vivo and previously in vivo on humans for BMDBM showed good correlations vitro/ex vivo and vitro/vivo for both butyl BMDBM, as the lipophilic permeant, and MB, as the hydrophilic permeant, by using TS20 as well as both STS and ME models. With the aim of providing detailed understanding about the organogelator behaviour and organization within the models and find possible parameters playing a key-role in SC permeation prediction a multi-analytical approach was adopted. All the models did not flow upon tube tilting and could be described as gels, with the exception of STS10 model that appeared as thick liquid being gelator concentration lower than mgc value. Unlike SA and TS models that exhibited networks capable of immobilizing completely the solvent, STS and ME10 models revealed the syneresis phenomenon according to gelator concentration. The actual presence of water within STS aggregates (reverse micelles) of ME models was demonstrated by means of TG/DTA analysis showing two thermal events in the range of about 50-130°C related to removal of water molecules. Unlike the pure gelators, XRPD profiles from all the SC models exhibited a broad peak at about 20° 2θ indicating the presence of a networked structure of the gelators where the width of the peak at half maximum is dependent on the crystallinity of the sample, which in turn is dependent on non-covalent interactions amongst the gelator molecules responsible for the formation of an ordered structure. Intermolecular interactions also arisen from FT-IR spectra showing subsided ester group stretching in TS, STS, and ME models. Architectural arrangements of the organogelators within TS, STS, and ME models, as outlined by microscopy analyses, involved round or worm-like architectures of spherulitic clusters. Under polarized light, the occurrence of birefringence revealed the so-called “maltese crosses” in STS models that are characteristic of liquid crystals with lamellar structures. The results demonstrated the relevant role of both the arrangement of gelator packing and crystallinity extent in mimicking SC in vivo/ex vivo skin permeation of both lipophilic and hydrophilic compounds. These findings could account for the behaviour and development of other artificial skin models involving different materials for the skin permeation prediction
Colouring effects of synthetic inorganic cobalt-pigments in fast-fired porcelainized stoneware tiles
No full textThe paper reports a laboratory and industrial study on the rationalization of using synthetic cobalt oxide, aluminate and silicate pigments (0.5-4.0 wt%) for colouring porcelainized stoneware tiles. The addition of pigments to the base body in amounts up to about 1-2 wt% does not appreciably modify microstructure, nature and amount of phases of the fired tiles; while higher amounts, promoting liquid-phase formation, favour the sintering and can cause swelling of compact samples. On the basis of the results, inorganic cobalt-pigments seem very appropriate to produce coloured porcelainized stoneware tiles, but the better results are obtained by using CoO.AI(2)O(3). By controlling type and amount of pigment, it is possible to tailor different blue shades conferring to the product particularly interesting aesthetic effects
Application of heating microscopy on sintering and melting behaviour of natural sands of archaeological interest
No full textIn antiquity, beach sand was one of the main raw materials for glass-making and for the production of other vitreous materials, like Egyptian blue and faience. During the 1st century AD, glass and pigments manufacturing industry was active along the Gulf of Naples, Italy, where we sampled four littoral sands. Samples were analyzed with different techniques: chemical analysis was performed by means of X-Ray Fluorescence (XRF) and mineralogical analyses with X-Ray Powder Diffraction (XRPD) and Raman Spectroscopy. The complete sintering to melting thermal behaviour of the four sands was studied by heating microscopy or hot-stage microscope (HSM) equipped with an high resolution camera capable to collect sample profile during heating. The effect of the grain size on the sintering curves, which were automatically elaborated by specimen profile transformation, was also investigated. Finally, some deductions about the granulometry effect and the presence of alkaline and alkaline-earth oxides on sintering and melting behaviour were drawn. All the four sands were found suitable for highly sintered manufacts rather than glasses, to reach complete amorphous materials the addition of fluxes was necessary
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