1,721,080 research outputs found
Formation of cellulose acetate-graphene oxide nanocomposites by supercritical CO2 assisted phase inversion
Full text linkCellulose acetate (CA)/graphene oxide (GO) nanocomposite membranes were generated by an assisted phase inversion process, based on the use of SC-CO2 as nonsolvent, operating at 200 bar and 40 °C; loadings of GO up to 9% w/w were tested. The structures maintained the cellular morphology, characteristics of CA membranes, also at the highest GO loadings used, with a porosity of about 80%, but the presence of GO influenced the pore sizes, that ranged between about 9 and 16 μm. The starting GO and the nanocomposite structures were characterized by the combination of various techniques that evidence as sulfur and chlorinated impurities, that were present in the starting GO material, were completely eliminated by the interaction with SC-CO2 during structures formation; moreover, a partial reduction of GO to graphene was also observed
Xylene isomerization in a membrane reactor. Part I: The synthesis of MFI membranes for the p-xylene separation
Full text linkThe synthesis and characterization of silicalite and ZSM-5 films supported on porous SS tubes are described. Composite membranes were used to separate xylene isomers between 150 and 400 °C. Permeation measurements of the individual isomers and the ternary mixture were performed at each temperature within this interval. N2 permeation measurements together with SEM observations were used to determine whether or not cracks and/or pinholes developed after exposure to the xylene isomers at high temperature. The ZSM-5 membrane was superior to the silicalite one because of its higher permeance flux (1.16 × 10-5 mol s-1 m-2), separation factors (p/o 4.4), and up to 400 °C stability.Fil: Tarditi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Irusta, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Lombardo, Eduardo Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin
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
Influence of La incorporation on the catalytic activity of Ru/ETS-10 catalysts for hydrogen production
Full text linkThe incorporation of lanthanum on ETS-10 titanosilicate and its influence on the catalytic activity of Ru catalysts for the dry reforming of methane reaction were studied. The catalysts were prepared through ion exchange of ETS-10 using different lanthanum solution concentrations (0.1, 0.2 and 0.4 % wt of La2O3). The Ru loading was 0.6 wt.% for all catalysts. The methane reaction rates for Ru/LaETS-10 catalysts showed an increase in comparison with Ru/ETS-10. This could be related to the lanthanum participation in the reaction mechanism. Moreover, all the formulations were stable after 70 h on stream. In order to study the effect of lanthanum exchange in the structure of ETS-10 supports, the solids were characterized by BET, XRD, TEM, FTIR XPS, and Laser Raman spectroscopy. The relative crystallinities were lower than 80%, indicating that the La exchange could have an important effect on the crystalline structure of ETS-10, in agreement with Raman and FTIR results. The surface Ru/Ti ratio determined by XPS was higher in the case of Ru/LaETS-10 synthesized with the highest La concentration in the exchange solution. The Na/Ti ratio, measured by XPS and EDX, was lower for the Ru/LaETS-10 catalysts compared with ETS-10 suggesting that La was exchanged in the structure.Fil: Faroldi, Betina María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Irusta, Silvia. Universidad de Zaragoza. Instituto de Nanociencia de Aragón; EspañaFil: Cornaglia, Laura Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin
Electrospinning synthesis and characterization of nanofibers of Co, Ce and mixed Co-Ce oxides. Their application to oxidation reactions of diesel soot and CO
No full textCo, Ce and Co-Ce nanofibers were synthesized by the electrospinning method. To obtain mixed fibers, Co was incorporated in two ways: one step synthesis and sequential synthesis. Nanofibers were applied to two reactions: gas-solid (CO oxidation) and solid-solid-gas (combustion of diesel soot). Different activity trends were observed in both reactions. For soot combustion, Co-Ce nanofibers were more active either than Co or Ce nanofibers. For CO oxidation instead, the activity order was Co > Co-Ce > Ce. Moreover, in the case of soot combustion, for all samples the temperature of maximum combustion rate occurred at a relatively narrow range (350−390 °C). On the contrary, for CO oxidation the temperature range for T50 was notably wider (150−325 °C). The high activity shown for all the samples for soot oxidation is related to the multiple contact points between the fibers and the soot particles, and the trend observed for CO oxidation related to the higher redox capacity of Co, as observed from CO-TPR experiments.Fil: Stegmayer, María Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Irusta, Silvia. Universidad de Zaragoza. Instituto de Nanociencia de Aragón; EspañaFil: Miro, Eduardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Milt, Viviana Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin
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