1,721,198 research outputs found
Effect of endothelial cell conditioned medium on the growth of human bone marrow fibroblasts
No full textA perspective of lanthanide promoted Ni-catalysts for CO2 hydrogenation to methane: catalytic activity and open challenges
No full textIn the frame of energy transition and anthropogenic CO2 emission reduction, CO2 hydrogenation by using green hydrogen to produce Synthetic Natural Gas is considered as a promising option. Considering nickel low-cost and natural abundance, Ni-based catalysts are the most investigated and used materials for methanation reaction in the temperature range 573–673 K. However, Ni-based catalysts showed inadequate low-temperature activity (below 473 K), low reducibility and dispersion, and catalyst deactivation due to particles sintering or even coke deposition. As well, for very low temperature application volatilization of the active phase through carbonyl production cannot be excluded. In recent years, lanthanides addition and in particular lanthanum and cerium, represents a good option in order to overcome the Ni-based catalyst limits. In this paper, a comprehensive review and overview of the most recent commercial formulation and advances in the development of lanthanides promoted Ni catalysts are reported, including the evaluation of the effect on the catalytic properties and the obtained catalytic performances
hydrolysis
No full textBACKGROUND: Lanthanum-based materials, namely La2O3 and La(OH)3, are of interest for several heterogeneous catalytic reactions because of their properties; that is, in spite of their poor resistance to CO2 and moisture, readily converting at room temperature to carbonates and oxycarbonates and requiring strong thermal treatments to revert back to their original form. RESULTS: In this study, hard template and hydrolysis synthetic procedures have been compared for the production of nanostructured La-based catalysts. The materials have been characterized by means of various techniques and tested in ethanol conversion as a probe reaction. Both preparation procedures give rise to higher surface areas than those reported for conventional synthesis and the surface properties are different, showing the formation of oxysulfate or of a complex mixture of carbonate and hydroxycarbonate. CONCLUSIONS: Lanthanum-based oxide can be efficiently prepared using different synthetic procedures that allow to obtain nanosized La-based mixed oxides. However, great attention should be paid to the preparation step, because the role of impurities markedly affects the stability and the catalytic properties of the prepared oxide. The use of the hard templating procedure allows a reduction of the amount of carbonate upon air exposure, thus stabilizing the starting oxide, by protecting the surface with the presence of lanthanum oxysulfate (La2O2SO4). © 2020 Society of Chemical Industry
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
Arsenic leaching from a gold bearing enargite flotation concentrate
No full textThe high arsenic content of the flotation concentrate obtained from a gold-bearing enargite ore for
pyrometallurgical processing strongly diminishes its market value. An investigation has been carried out for
selectively leaching arsenic from enargite–luzonite minerals using alkaline Na2S solutions. By suitably
adjusting the main reaction conditions almost 98% arsenic was leached, as well as part of the gold,
particularly with high Na2S concentrations. Copper was not lost from the solid phase in which the enargite is
converted into a new species with the chemical formula Cu1.5S.
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