1,721,009 research outputs found
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
Plastic Additives
No full textAdditives are essential components of plastic formulations providing maintenance and/or modification of polymer properties, performance, and long‐term use. Additive means any ingredient which is incorporated in a polymer (or a polymer blend), which is usually the main component, to provide a plastic formulation with adjusted properties. The extension of polymer properties by additives has been playing a substantial role in the growth of plastics, and many polymer applications are only accessible in the presence of a number of ingredients, often only in small quantities, in addition to the polymer itself. As real new polymer structures of standard plastics or engineering plastics are not introduced any more, additives drive innovation in the plastics area to design properties and functions of polymers
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
Polymer Additives
No full text409444Additives are essential components of plastic formulations providing maintenance and/or modification of polymer properties, performance and long-term use. Historically polymer additives were decisive for the development of thermoplastic material applications. This chapter presents the most important classes of additives (antioxidants, PVC heat stabilizers, light stabilizers, and flame retardants). It provides general information on chemical structures and mechanisms, on testing methods and on use examples in selected polymer classes. The chapter summarizes other important additive classes. The compounds used today as PVC heat stabilizers are based on mixed metal salts, for example calcium/zinc, organo-tin compounds, and metal-free organic-based systems. Plasticizers in the form of additives act as processing aids, reduce the melting and processing temperature of the polymer, and modify the polymer properties, for example reducing the elastic modulus and making it more flexible and softer. Impact modifiers are used to toughen rigid PVC and polystyrenes
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
Polymere mit anhängenden Fluoranthenylgruppen und Modellverbindungen Synthese u. Unters. ihrer Elektronen-Donor-Acceptor-Komplexbildungseigenschaften
No full text(Photo)oxidative degradation and stabilization of flame retarded polymers
No full textS.2430-2435Flame retarded polymer formulations are mainly used in long-term applications whereas antioxidants, light stabilizers and co-additives provide the requested lifetime of plastic materials. However many flame retardants influence the oxidative and photooxidative stability of polymers often in a negative way resulting in early failure and loss in value. Moreover insufficient (photo)oxidative stability of the flame retardant itself may reduce the flame retardance performance over time. Therefore, there is a need to develop adjusted stabilizer systems considering the type of flame retardant, the polymer substrate and the intended application. Therefore, the influence of flame retardants on the (photo)oxidative stability of selected polymers is reviewed and strategies to extend the lifetime of flame retarded polymers are provided. In addition, the specific requirements of the stabilization of nanocomposites as potential flame retardant components are covered.98Nr.1
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