1,720,979 research outputs found
Synthesis of hydrophobic MIL-53(Al) nanoparticles in low molecular weight alcohols: systematic investigation of solvent effects
No full textThe effects of using low-weight alcohols, methanol and ethanol, for the synthesis of MIL-53(Al) are investigated and the results directly compared with analogous synthesis in water and N,N-dimethylformamide (DMF). When methanol is employed in the synthesis of MIL-53(Al), termed MIL 53(MeOH), several unique properties are observed. The breathing phenomenon which is known for MIL-53(Al) derivatives, prepared using water or DMF as reaction solvent, is not observed for samples prepared from methanol and the framework adopts, and remains in, the large-pore form. Thus, measurement of N2-isotherms and calculation of internal surface areas have verified that the synthesis of MIL-53(MeOH) leads to a product which is highly porous without the requirement for an energy-consuming activation process. Furthermore, X-ray diffraction measurements and scanning electron microscopy at different humidity levels reveal a reversible loss of crystallinity at high humidity levels for MIL-53(MeOH) which was not observed previously for any other known MIL-53 derivative. In contrast the synthesis of MIL-53(Al) in ethanol leads of a product with low crystallinity
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No full text“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
No full textWe 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
No full textWe 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
A comparative study of heavy metals removal using agricultural waste biosorbents
No full textThe adsorption capabilities of rice husk, coconut coir and moringa seeds were evaluated for the first time under the same experimental conditions for the removal of copper (Cu), nickel (Ni) and zinc (Zn from underground water. The effects of adsorbent dosage, pH and contact time were studied. Copper and nickel were removed up to 99%, using rice husk, coconut coir and moringa seeds. Zinc concentrations can only be reduced to up to 70% using rice husk. However, removal was reached 99% when coconut coir and moringa seeds were used. Moring seeds showed the highest adsorption capacities (Zn = 42.3 mg g−1, Cu = 23.3 mg g−1, Ni = 16.1 mg g−1) among the biosorbents tested. Nickel was the least adsorbed heavy metal for all biosorbents studied. Moringa seeds leached sulfur at acidic pH values (< 4). Models showed that adsorption using these biosorbents follows Langmuir isotherm and Pseudo-second order kinetic
Cobalt hydroxide to ZIF-67: A novel water-based electrochemical deposition
No full textThis study presents, a novel approach to electrochemically deposit continuous ZIF-67 films with controlled thickness. ZIF-67 is a zeolite imidazolate framework material comprised of tetrahedral cobalt (Co) cations and 2-methylimidazolate (HMim) linker in a zeolite-like sodalite (SOD) topology. We firstly deposited a layer of cobalt hydroxide (Co(OH)2) then the hydroxide layer was cathodically transformed to highly crystalline ZIF-67 films in HMim solution. Parameters such as concentrations of reactants, number of cyclic voltammetry (CV) scans and electrodeposition time were investigated while water was used as the solvent.Results showed that low concentrations of metal salt (Co(NO3)2 < 0.05 M) and linker (HMim < 1.75 M) were not sufficient to form a continuous coverage of either (Co(OH)2) or ZIF-67, respectively. Using a concentration of 0.099 M Co(NO3)2 and 1.75 M HMim yielded in ZIF-67 films with high crystallinity and homogeneous morphology. Increasing the electrodeposition time from 5 to 60 min showed a remarkable change in the ZIF-67 surface coverage (from 67% to 100%, respectively based on the morphological coverage). Film thickness was increased from 0.83 ± 0.12 μm to 3.00 ± 0.18 μm by increasing the number of CV cycles from 2 to 15, respectively. The developed approach was tested for scaling up the three-electrode cell from coating a 1 X 4 cm2 substrate to 25 X 25 cm2 in which the deposited scaled up ZIF-67 films had the same morphology and crystallinity of the small-scale substrate.Finally, the feasibility of using the developed films in the application of electrooxidation of methanol was explored. The developed films demonstrated a potential and consistent cycling performance across 50 cycles
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