1,720,977 research outputs found
Surface etching of HKUST-1 promoted via supramolecular interactions for chromatography
No full textThe addition of guanidinium-based surfactants to the synthesis of HKUST-1 reveals a novel surface patterning effect where meso- and macroscopic features appear on the MOF crystals. The size of the features increases with increasing alkyl chain length of the guanidinium amphiphiles, and their formation is strongly dependent on the presence of water which appears to more favourably etch the crystal surfaces when the surfactants are employed. The patterned crystals display intermediate type I/IV isotherms and the presence of the surface features have been evaluated for the chromatographic separation of styrene and ethylbenzene. Some degree of control over the interactions between the framework building blocks and the amphiphiles is afforded, and by simply changing the order of addition of the reactants the guanidinium surfactants promote the formation of HKUST-1 nanoparticles
Silica SOS@HKUST-1 composite microspheres as easily packed stationary phases for fast separation
No full textMetal–organic frameworks (MOFs) have been investigated for separations including chromatography. Typically, MOF particles are directly packed into columns for the separations. The irregular shapes and wide size distributions of MOF particles have led to difficulty in column packing and low column efficiency or high back pressure. We describe here the preparation of MOF–silica microspheres as packing materials for fast and efficient liquid chromatography. Spheres-on-sphere (SOS) silica particles are prepared, modified with –COOH and –NH2 groups, and then used as support to grow HKUST-1. HKUST-1 nanocrystals and films are formed and attached firmly onto the SOS particles with adjustable porosity. The composite microspheres, showing core–shell properties, are directly packed into columns to offer separation capability of MOFs and efficient packing and support of silica microspheres. These columns show separation of toluene/ethylbenzene/styrene and toluene/o-xylene/thiophene within 1.5 minutes. Although HKUST-1 is not good for separating xylene isomers, the separation can be achieved in 5 minutes using the composite microspheres after conditioning the column with dichloromethane or toluene. Remarkably, it is observed that conditioning with DCM can change retention time and selectivity (elution order) of xylene isomers. It is also possible to produce other types of MOFs (e.g., ZIF-8) on the SOS particles, indicating the potential of this method for wider applications
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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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