1,721,052 research outputs found
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
Development of Synthesis Strategy of Ferric and Clayey Flat Ceramic Membranes
No full textCeramic membranes prepared with flat sheet configuration using local materials, iron ore and bentonite, are reported in this investigation. The feedstocks used were fully characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) and laser diffraction/light scattering. In order to optimize the preparation conditions, the effect of sintering temperature on the microstructure of ferric and clayey membranes was assessed. Results obtained with SEM, confirmed by optical microscopy, indicate that the optimized sintering temperature was in the vicinity of 900 °C. The properties of the fabricated membranes were characterized in terms of mass and thickness loss throughout a determined period of time. The experimental results present a negligible variation in the rate of mass change, which suggested the stability of the synthesized membranes. Both the ferric and clayey membranes exhibit a prevalence of mesopores in their pore distribution. These results suggest that these specific membranes could be employed as cost-effective and environmentally friendly materials. Furthermore, they hold promise for potential applications in gas treatment processes
Acid and Alkali Pre-treatment Studies on Brewer’s Spent Grains (BSG)
No full textOne of the main by product obtained during beer production in the brewing industry is brewer’s spent grains (BSG). They are rich in cellulose, hemicellulose, lignin, and proteins. The aim of the work is to explore the effect of acid and alkali pre-treatments on BSG by studying the solubilisation behaviour of the organic molecules. BSG is chemically pre-treated using (alkali addition using NaOH, acid addition-HCl) by varying the concentration. After the pre-treatments, analyses such as pH measurements, total sugars using refractometer, reducing sugars using 3,5-Dinitrosalicylic acid (DNS) Miller’s method, total polyphenols using Folin–Ciocalteu method, proteins using Lowry method are carried out on the liquid phase. The results obtained could provide better insights into efficient chemical pre-treatment studies of BSG and further valorisation
Effect of large d0 cation doping on gamma-alumina's acid–base and catalytic properties
No full textBACKGROUND: Catalysts based on alumina-supported metal oxides are of crucial importance in the field of heterogeneous catalysis for several applications requiring tuning of surface acidity.
RESULTS: In this work, the effects of K+, Ca2+ and La3+ cation doping have been evaluated on a well-characterized commercial gamma-Al2O3 through morphological characterization and surface characterization (Brunauer–Emmet–Teller, X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy). The conversion of ethanol as a test reaction
was performed over these catalysts. The impregnated oxide species essentially remain at the surface, resulting in the partial poisoning of the strongest alumina Lewis acid sites. Moreover, oxide anions may increase basicity at the surface. The doping results in a significant decrease in catalytic activity in ethanol conversion to diethyl ether and to ethylene, which is shifted at higher temperatures. On the other side, higher activity in the formation of C4 olefins was detected, namely on the K-doped
alumina.
CONCLUSION: The partial poisoning of the strongest alumina Lewis acid sites and the presence at the surface of new more basic cation–anion couples result in significant changes in catalytic ethanol conversion
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