1,720,971 research outputs found
Reuse and Valorisation of Hemp Fibres and Rice Husk Particles for Fire Resistant Fibreboards and Particleboards
Full text linkThe present manuscript deals with the reuse and valorisation of agricultural wastes and by-products (namely, hemp fibres and rice husk particles) to produce fire retardant fibreboards and particleboards for applications in biobuilding. Since fire retardancy is one of the most important challenges, a detailed study on the thermal and flame retardant properties of the above materials assembled using starch as the binder and different ammonium dihydrogen phosphate contents as fire retardant agents, is proposed. The combustion properties have been investigated in developing fire conditions, employing a radiating heat flux of 35 kW/m2generated by a cone calorimeter. An optimised formulation able to make both fibreboards and particleboards not ignitable has been found and is predicted to be “A2/B” class in the European fire classification for building products. The resultant materials have proven to undergo pyrolysis and not to burn, favouring the formation of a dense and consistent final residue
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
Rice husk as bio-source of silica: preparation and characterization of silica bio-composites
Full text linkSilica powder has been extracted from rice husk, employing a simple extraction procedure for preparing poly(lactic acid) bio-composites with differ filler contents (namely, 5, 10, 20 and 30 wt.-%). These materials have been obtained through a semi-industrial process of extrusion. The thermal, mechanical and morphological properties have been investigated. In spite of a broad distribution of silica particle size, the prepared bio-composites have exhibited improved storage modulus and reduced oxygen permeabilities. The collected values at 10 and 30 wt.-% have been compared with those of homologous samples prepared using a commercial silica. Two micro-mechanical models (Voigt and Halpin-Tsai) have been used to fit the mechanical data, as well. Finally, an economic analysis of material and energetic costs has been performed on samples containing silica from rice husk in order to establish if the proposed process is sustainable or advantageou
Plasticizers, antioxidants and reinforcement fillers from hazelnut skin and cocoa by-products: extraction and use in PLA and PP
No full textThe selective and serial extraction of natural additives from hazelnut skin and cocoa by-products has been carried out for giving a high-added value to poly(lactic acid) and poly(propylene) (PLA and PP). Through the proposed process, three fractions mainly containing plasticizers, antioxidants and reinforcement fillers have been consecutively separated. These have been subsequently characterized from the chemical and thermal point of view (assessed by infrared spectroscopy, differential scanning calorimetry and thermogravimetry), and then melt-blended with PLA or PP. Thus, the first fraction has been used for plasticizing PLA, the second one for UV-protecting PP, and the last one for reinforcing both matrices. The collected results by dynamic mechanical thermal analysis have shown that the first fraction partially plasticized PLA. The second fraction turned out to be consisting of UV absorbers as well as thermal stabilizers that increased PP oxidation induction time (of 30%) in the case of hazelnut skin, and PP thermal stability (of 26 °C in air) in the case of cocoa, respectively. The last fraction was capable to increase the storage modulus of PLA and PP up to 30 and 20% (with 30 wt.-% of filler content), respectively
Poly(lactic acid)-based composites containing natural fillers: thermal, mechanical and barrier properties
No full textNatural filler/poly(lactic acid)-Based composites have been prepared by melt blending in order to investigate the resulting thermal, mechanical, and oxygen permeability properties. To this aim, several wastes or by-products (namely, cellulose fibers, wood sawdust, hazelnut shells, flax fibers, corn cob and starch) have been used, ranging from 10 to 30 wt%. The presence of these fillers is responsible of a slight reduction of the polymer degradation temperature in nitrogen as well as of a significant increase of the storage modulus as a function of the filler content. The experimental data obtained by dynamic mechanical analysis have been mathematically fitted, employing three micromechanical models (namely, Voigt, Reuss and Halpin-Tsai). Furthermore, the presence of cellulose or starch has turned out to significantly reduce the polymer oxygen permeability. Finally, in order to fully assess the feasibility of such materials, an economic analysis has been carried out and 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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