1,720,977 research outputs found
Materiale composito formato da un biofiller e da una matrice termoplastica e procedimento per realizzare un articolo con un tale materiale composito
No full textProgettazioni di plastiche derivanti dal vino: scarti vitivinicoli come substrato di sintesi, additivi e fillers per differenti polimeri e biopolimeri.
No full textNegli ultimi decenni, a causa della sempre maggiore e più diffusa preoccupazione ambientale, l’industria e la ricerca scientifica si sono concentrati sullo sviluppo di nuovi processi, materiali e sistemi meno impattanti. Così, nel mondo della plastica, i polimeri da fonte rinnovabile (bio-based) e/o quelli biodegradabili hanno guadagnato una grande attenzione in quanto promettenti soluzioni per la risoluzione o riduzione della dipendenza dal petrolio e/o dell’inquinamento della plastica. Tuttavia questi nuovi polimeri naturali coprono ad oggi solo ristrette porzioni di mercato in quanto più costosi e meno conosciuti in termini di know-how rispetto ai polimeri convenzionali di origine petrolchimica. Quindi, da un punto di vista globale più ampio, la presente dissertazione deve essere vista come un capitolo facente parte di un insieme collettivo di più ricerche animate dal fine condiviso di favorire la bio-raffineria in larga scala a scapito della raffineria petrolchimica, ricucendo il loro gap di competenze tramite l’apporto di nuove idee e risultati. Entrando nel vivo degli argomenti, il presente lavoro ha investigato la possibilità di valorizzare gli scarti agro-industriali provenienti dalle cantine vitivinicole nel mondo dei polimeri e biopolimeri secondo diversi approcci. In tal modo, mettendo in contatto due mondi apparentemente separati come quelli della plastica e del vino, si è sia reso possibile lo sviluppo di nuovi materiali eco-friendly che fornite nuove soluzioni per lo smaltimento dei rifiuti della lavorazione del vino, in linea con quanto voluto dalle nuove politiche di sostenibilità, rinnovabilità ed economia circolare. Diversi sottoprodotti vitivinicoli sono stati campionati, caratterizzati e sfruttati a seconda delle loro proprietà e potenzialità. In genere, gli scarti ricchi di polifenoli e/o i loro estratti sono stati testati come stabilizzanti naturali all’interno del Polipropilene (PP), del Poli(idrossibutirrato) (PHB) e del Poli(butilene succinato) (PBS), investigando la risposta dei bio-stabilizzanti sia alla degradazione a breve e lungo termine (termica e/o da UV) che alla biodegradazione in diversi ambienti. Parallelamente, gli scarti lignocellulosici o con frazioni importanti di materiale inorganico sono stati studiati come filler naturali rinforzanti a basso costo all’interno del Poli(idrossibutirrato) (PHB), Poli(idrossibutirrato-co-idrossiesanoato) (PHBH), Poli(idrossibutirrato-co-idrossivalerato) (PHBV), Poli(butilene succinato) (PBS), Poliammide 11 (PA11) e del Poli(acido lattico) (PLA). I bio-compositi sono stati investigati da un punto di vista termico, meccanico e reologico, sfruttando anche modelli micromeccanici per la comprensione dell’effetto del filler vitivinicolo sulle proprietà dei biopolimeri. Infine, gli step necessari per sintetizzare direttamente i Poli(idrossialcanoati) (PHAs) a catena corta (-scl) utilizzando gli scarti vitivinicoli come substrato di fermentazioni sono stati parzialmente discussi. Ogni argomento è stato trattato da un punto di vista sia teorico che sperimentale in modo tale da modellare, comprendere e controllare il comportamento dei nuovi materiali che, nello stesso tempo, sono stati anche oggetti di valutazioni economiche per la fattibilità del loro trasferimento in larga scala.In the last decades, the increasing global environmental concern has lead industry and scientific academia to focus in new eco-friendly and renewable processes, materials and systems. Considering the plastics sector, biodegradable and bio-based polymers have gained a great attention as promising solutions to solve or reduce the crude oil dependence and/or the plastic pollution issues. By the way, these natural polymers still cover restricted portion of the market because of both their higher prices and the lack of knowledge, if compared with classical petrochemical polymers. Therefore, from an overall point of view, the present dissertation should be seen as a detailed part of a broader context in which it is attempted to bridge the maturity gap between the concepts of petrochemical and bio-refineries and to promote their progressive switch in large-scale by the contribution of new ideas, results and know-hows. Going into details, the present work has investigated the possibility to valorize the agro-industrial wastes derived from the wine companies within different polymers and biopolymers through several approaches. Two apparently distinct processes as plastic and winemaking have been put in contact, offering new suitable products able to solve at the same time the green materials necessity and the agro-wastes disposal problems in accordance with the principles of sustainability, circular economy, renewability and low environmental footprint. Different solid wine wastes have been collected, characterized and exploited in different ways depending on their evaluated properties and potentiality. Generally, wastes rich in polyphenols and/or their extracts have been tested as natural stabilizers within Polypropylene (PP), Poly(hydroxybutyrate) (PHB) and Poly(butylene Succinate) (PBS) investigating the response of the bio-stabilizers to short and long-terms degradation (thermal and/or UV) as well as to biodegradation in different environments. At the same time, wastes with high inorganic or lignocellulosic fractions have been studied as reinforcement cost-effective natural fillers within Poly(hydroxybutyrate) (PHB), Poly(3-hydroxybutyrate-co-hydroxyhexanoate) (PHBH), Poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV), Poly(butylene Succinate) (PBS), Polyamide 11 (PA11) and Poly(lactic acid) (PLA). Bio-composites have been mainly investigated from a thermal, mechanical and rheological point of view, exploiting also micro-mechanics models to deeper understand the effect of the wine-derived fillers on the biopolymers properties. Finally, steps to directly synthesise scl-Poly(hydroxyalkanoate)s (PHAs) starting from wine wastes as substrate have been also partially discussed. Each treated topic has been handled from a theoretical and experimental point of view in order to model and control the behaviour of these new wine-based materials and simultaneously, economical essays have been carried out in order to point out the concrete feasibility to transfer these wine-based materials to large-scale apparatuses
Atteggiamenti educativi e insegnamento linguistico: fattori di inserimento o di dispersione scolastica
No full textIl contributo affronta i problemi dell’inserimento scolastico, della dispersione scolastica e della riuscita dei percorsi educativi in relazione all’insegnamento/apprendimento dell’italiano L
Atteggiamenti educativi e insegnamento linguistico: fattori di inserimento o di dispersione scolastica
No full textIl contributo affronta i problemi dell’inserimento scolastico, della dispersione scolastica e della riuscita dei percorsi educativi in relazione all’insegnamento/apprendimento dell’italiano L
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
Thermal and UV aging of polypropylene stabilized by wine seeds wastes and their extracts
Full text linkA commercial tannin wine seed extract powder (T), a seed polyphenol extract (Sext) and virgin wine seeds wastes (Se) have been mixed with polypropylene (PP) and tested as long-term stabilizers. Their stabilizing activity has been compared with that of a synthetic antioxidant commonly used within PP (Irganox 1010). Each sample has been subject to both UV and thermal aging. The PP-based films photo-oxidation has been followed through the C=O formation over the aging time by FT-IR. The PP-based tensile specimens have been oven aged and the mechanical properties loss has been investigated monitoring the variation of the elongation at break. Melt Flow Index (MFI) measures and Different Scanning Calorimetry analysis have been conducted on thermally aged samples. At the same time, wine derived additives have been characterized in terms of total polyphenol content, FT-IR and UV/VIS spectra meanwhile catechin and gallic acid have been quantified by LC-MS. Experimental results have evidenced the ability of all the wine derived additives to withstand both to thermal and UV long-term degradation. In particular, wine seeds extracts exhibit the best results in terms of stabilization (even better than Irganox 1010) without compromising the PP mechanical, thermal, morphological and rheological properties
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