1,720,987 research outputs found
Crystal desolvation induced by polymer-assisted grinding
No full textMechanochemistry is a relatively new discipline defined by IUPAC as "one of the ten most important chemistry innovations that will change the world". Indeed, several independent studies have demonstrated that the use of mechanical force to induce and sustain chemical transformations is often superior to other more consolidated approaches. Mechanochemical reactions performed in the presence of catalytic amounts of a polymer (polymer –assisted grinding, POLAG1) are particularly interesting since the added polymer gives additional suitable conditions for the obtainment of the desired solid form. Specifically to the multi-component mixtures, solids that are omnipresent in materials science, the understanding of the overall stability and a mechanistic explanation of several phenomena related to their formation and/or production is often difficult. In this talk, I investigate at the molecular level the mechanisms of solid state desolvation of solvated/hydrated systems where mixing of the ingredients in the presence of polymers is accelerated through mechanochemistry. An efficient combination of experimental and computational experiments can reveal the types of interactions among the different components that are relevant for driving the solid state reaction towards the desired product. Whilst focusing on model systems, these studies provide an important guideline of the steps that need to be taken for understanding the mechanisms involved in solid state reactions. Furthermore, such examples open new possibilities for understanding solid state reactions than can subsequently be used for real-world applications. Finally, desolvation through POLAG method can accelerate the search for solid forms and is widely applicable to different types of solid mixtures for optimizing a variety of properties
Forced to govern the unknown: on the role of the added liquid or polymer in mechanochemical solid forms screens
No full textMechanochemistry - the use of mechanical force to induce and sustain chemical transformations has recently been highlighted by IUPAC as "one of the ten most important chemistry innovations that will change the world". Although such discipline is relatively new with a significant growth of interest observed particularly over the last three decades, several independent studies have demonstrated mechanochemistry to be effective and often superior to other approaches for the discovery of new solid forms. The propensity of a specific molecule to give different polymorphs and/or form multicomponent crystals can be assessed mechanochemically by changes in the exact conditions of the reaction, including neat grinding (NG), variable temperature grinding (VATEG), liquid-assisted grinding (LAG), variable amount LAG (VALAG), ion liquid-assisted grinding (ILAG) and polymer-assisted grinding (POLAG). Mechanochemical reactions performed in the presence of catalytic amounts of a liquid or polymer are particularly interesting since the added liquid or polymer gives additional suitable conditions for the obtainment of the desired solid form. At the same time, however, the understanding of the mechanisms involved during mechanochemical reactions in the presence of a liquid or polymer remains vague, thus limiting our capabilities to control mechanochemical reaction. In this context, several research groups have recently produced important contributions, mainly due to serendipitous events. This presentation has particular focus on the effect of the catalysts available in mechanochemistry, and relates the outcomes both to the operational conditions such as the amount and to their chemical characteristics. Some relevant examples already available in literature will be mentioned, and the most recent result in our laboratory will be also presente
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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