1,721,413 research outputs found
Preparation of coemissive luminescent nanoparticles in continuous‐flow microreactors for efficient light‐harvesting systems
No full textMechanochromic fluorescent polymers with aggregation-induced emission features
Full text linkMechanochromic polymers are defined as materials that are able to detect a mechanical stress through an optical output. This feature has evoked a growing interest in the last decades, thanks to the progress of chromogenic molecules whose optical characteristics and chemical functionalities allow their effective insertion in many thermoplastic and thermoset matrices. Among the different types of fluorogenic probes able to detect mechanical solicitations, those with aggregation-induced emission (i.e., AIEgens) have attracted tremendous interest since their discovery in 2001. In the present review, the main principles behind the AIEgens working behavior are introduced along with the current state of knowledge concerning the design and preparation of the derived mechanochromic fluorescent polymers. Examples are provided concerning the most ingenious solution for the preparation of chromogenic materials, starting from different types of commodity plastics or synthetic polymers and combined with the latest AIE technology to provide the most sensitive response to mechanical stress
A random-walk based scoring algorithm with application to recommender systems for large-scale e-commerce
No full textResearch Paper Recommender Systems: A Random-Walk Based Approach
No full textEvery day researchers from all over the world have to filter the huge mass of existing research papers with the crucial aim of finding out useful publications related to their current work. In this paper we propose a research paper recommending algorithm based on the Citation Graph and random-walker properties. The PaperRank algorithm is able to assign a preference score to a set of documents contained in a digital library and linked one each other by bibliographic references. A data set of papers extracted by ACM Portal has been used for testing and very promising performances have been measured
ItemRank: A Random-Walk Based Scoring Algorithm for Recommender Engines
No full textRecommender systems are an emerging technology that helps consumers to find interesting products. A recommender system makes personalized product suggestions by extracting knowledge from the previous users interactions. In this paper, we present "ItemRank", a random-walk based scoring algorithm, which can be used to rank products according to expected user preferences, in order to recommend top-rank items to potentially interested users. We tested our algorithm on a standard database, the MovieLens data set, which contains data collected from a popular recommender system on movies, that has been widely exploited as a benchmark for evaluating recently proposed approaches to recommender system (e. g. [Fouss et al., 2005; Sarwar et al., 2002]). We compared ItemRank with other state-of-the-art ranking techniques (in particular the algorithms described in [Fouss et al., 2005]). Our experiments show that ItemRank performs better than the other algorithms we compared to and, at the same time, it is less complex than other proposed algorithms with respect to memory usage and computational cost too
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
Waterborne Acrylic Resin Containing Luminescent Eu3+ Pigments for Luminescent Solar Concentrators
No full textThis study reports the use of waterborne acrylic resin as a polymer matrix for thin-film luminescent solar concentrators (LSC). A water dispersable lanthanide complex based on commercially available Eu3+ chelate (Lumilux SDP Red, Lu Red) is utilized as the red-emitting pigment. The derived thin polymer films of about 100 mu m show absorptions of the organic ligand comprised between 300 and 400 nm, flanked by scattering phenomena caused by the presence of the micro-sized pigment particles, whose dispersion is not adversely affected by concentration. The film's emission displays the typical fluorescence of Eu3+ chelates around 600 nm with quantum yields between 20 and 36%. External quantum efficiencies (eta(ext)) are found to increase up to 4-4.5% with Lu Red content less than 10-15%, while dropping to about 3% at the highest content, possibly due to the adverse influence of the scattering phenomena within the waveguide. Maximum device efficiencies (eta(dev)) of 0.70% confirm the potentiality offered by the new LSC systems, thus definitely supporting the waterborne polymer matrices for the development of high-performance and water-based solar collectors
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