1,720,969 research outputs found
Crosslinked polytriazole membranes for organophilic filtration
Full text linkWe report the preparation of crosslinked membranes for organophilic filtration, by reacting a new polytriazole
with free OH groups, using non-toxic poly (ethylene glycol) diglycidyl ether (PEGDE). The OH-functionalized
polymer was obtained by converting the oxadiazole to triazole rings with high yield (98%). The maximum degree
of crosslinking is achieved after 6 h of reaction. The crosslinked polytriazole membranes are stable in a wide
range of organic solvents and show high creep recovery, indicating the robustness of crosslinked membranes.
The influence of different casting solutions and different crosslinking time on the membrane morphology and
membrane performance was investigated. The membranes performance was studied in dimethylformamide
(DMF) and (tetrahydrofuran) THF. We achieved a permeance for THF of 49 L m−2 h−1 bar−1 for membranes
with molecular weight cut off (MWCO) of 7 kg mol−1 and a permeance for THF of 17.5 L m−2 h−1 bar−1 for
membranes with MWCO of 3 kg mol−1
. Our data indicate that by using the new polytriazole is possible to adjust
the pore dimensions of the membranes to have a MWCO, which covers ultra- and nanofiltration range
Sustainable manufacture of organic solvent nanofiltration membranes
No full textMembranes are a robust, reliable and economical technology. However, polymeric membranes are manufactured from polymeric and organic solvent sources derived from petrochemical sources. The high volatile organic compounds (VOC) emissions of the organic solvents and the non-recyclability of the polymers often question the membrane manufacture sustainability.
The main goal of this dissertation is the preparation of polymeric membranes for liquid separation through more sustainable processes. We report here the green preparations of hollow fibers, thin-film composite and integrally skinned asymmetric membranes.
An important part of the work is represented by the development of cellulose hollow fibers from ionic liquid solutions, avoiding strong alkali or harsh solvents. By tuning the manufacturing process, we prove that the membranes can be used for different applications such as oil-water separation, protein separation via ion-exchange chromatography and solvent purification via organic solvent nanofiltration. The main advantages of using cellulose to prepare hollow fiber membranes are the biodegradability of the polymer and the intrinsic chemical stability.
Another significant milestone of this work is replacing volatile solvents such as hexane during the thin-film composite membrane manufacture. As green alternative solvents, we decided to use naturally extracted oleic acid and decanoic acid. Due to their low costs and volatility, they represent a valid alternative for industrial membrane preparation through the interfacial polymerization process. The membranes prepared with this process were used for solvent resistant nanofiltration.
Finally, by using ionic liquids as solvents, we improved the manufacturing sustainability polytriazole asymmetric membranes synthesized in the lab
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
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