1,720,979 research outputs found
Effects of Al(OH)O nanoparticle agglomerate size in epoxy resin on tension, bending and fracture properties
Get PDFSeveral epoxy Al(OH)O (boehmite) dispersions in an epoxy resin are produced in a kneader to study the mecha-nistic correlation between the nanoparticle size and mechanical properties of the prepared nanocomposites. The agglomerate size is set by a targeted variation in solid content and temperature during dispersion, resulting in a different level of stress intensity and thus a different final agglomerate size during the process. The suspension viscosity was used for the estimation of stress energy in laminar shear flow. Agglomerate size measurements are executed via dynamic light scattering to ensure the quality of the produced dispersions. Furthermore, various nanocomposite samples are prepared for three point bending, tension and fracture toughness tests. The screening of the size effect is executed with at least seven samples per agglomerate size and test method. The variation of solid content is found to be a reliable method to adjust the agglomerate size between 138-354 nm during dispersion. The size effect on the Young’s modulus and the critical stress intensity is only marginal. Nevertheless there is a statistically relevant trend showing a linear increase with a decrease in agglomerate size. In contrast, the size effect is more dominant to the sample’s strain and stress at failure. Unlike micro-scaled agglomerates or particles, which lead to embrittlement of the composite material, nano-scaled agglomerates or particles cause the composite elongation to be nearly of the same level as the base material. The observed effect is valid for agglomerate sizes between 138-354 nm and a particle mass fraction of 10 wt-%
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Socio-Economic Research on Nanoscale Science and Technology: A European Overview and Illustration
No full textAdvances in nanoscience and nanotechnology promise to have major impacts on human health, wealth, and peace in the coming decades. Among the expected breakthroughs are orders of magnitude increases in computer efficiency, human organ restoration using engineered tissue, `designer' materials created from directed assembly of atoms and molecules, and the emergence of entirely new phenomena in chemistry and physics. This book includes a collection of essays by leading scientists, engineers, and social scientists reviewing the possible uses of these impending technical developments in various industrial, medical, and national security applications, and the corresponding ethical, legal, social, economic, and educational issues that they raise. The report outlines potential areas for research into societal implications of nanotechnology, as well as some preliminary suggestions for how potential positive impacts of nanotechnology can be maximized, while minimizing any possible negative impacts, real or imagined. This book also provides the beginning of a blueprint for how one should address second-order consequences of the new technology, either positive implications or potential risks. This material was prepared under the auspices of the US National Nanotechnology Initiative (NNI). The issues raised in the book are global in scope, going far beyond the immediate impact of the NNI. They ask the general questions of how history and the human condition are affected by technological progress, and how individuals and institutions can seek to guide that progress in ways most beneficial to mankind in the long run
Network of Cooperation Between Science Organizations
No full textAppreciation of the fact that our planet functions as a system, i.e., the Earth System (ES), defined as “the
interacting physical, chemical and biological global-scale cycles (often called biogeochemical cycles) and
energy fluxes which provide the conditions necessary for life on this planet” (Oldfield F, Steffen W, The
earth system. In: Steffen W, Sanderson A, Tyson PD et al (eds) Global change and the earth system: a
planet under pressure. Springer, Berlin/Heidelberg/New York, p 7, 2004) has emerged over the last
approximately three decades. By definition, the study of this system – Earth System science – then relies
on the convergence of traditional natural science disciplines. Furthermore, however, because a salient
feature of the ES is that “human beings, their societies and their activities are an integral component of the
Earth System, and are not an outside force perturbing an otherwise natural system” (Oldfield F, SteffenW,
The earth system. In: SteffenW, Sanderson A, Tyson PD et al (eds) Global change and the earth system: a
planet under pressure. Springer, Berlin/Heidelberg/New York, p 7, 2004), Earth System science also relies
on the convergence of disciplines from the social sciences and humanities. This convergence of disciplines
has led to a current understanding of the function and behavior of our planet – as well as the role of
human activities in that function – that would not have been possible using a traditional disciplinary
approach. This chapter examines the role of international scientific networks in catalyzing the disciplinary
convergence necessary for Earth System science to evolve and concludes that these networks have likely
been of pivotal importance for this convergence
Variations on the Author
Get PDF“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
Get PDFWe 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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