1,720,958 research outputs found
An innovative method of thermal activation using microwaves
No full textA microwave insulated open end coaxial applicator is utilized for the thermal activation of chem. processes. The method enables to apply microwave power at 2,450 MHz, heating in situ the reacting materials with utmost efficiency. The safety conditions, the efficiency, the integration capability and the possibility of scaling-up of the method are discussed. The article presents also a few examples of the versatility of this new technol. applied in the prodn. of nano metal catalysts, useful for different catalyzed reactions, and in org. synthesis
An innovative microwave method for large scale preparation of nanocatalysts for industrial applications
No full textNanostructured metal catalysts are of great interest because of their marked catalytic performances. Consequently, different synthetic methods have been reported in literature but, up to now, all these methods present several drawbacks for their application on industrial scale. Today microwave chemistry is experiencing an exponential growth and it is generally performed using a closed metal cavity, i.e. a microwave oven. However, the current commercial systems present a number of relevant limitations. Multi-disciplinary applications are complicated or even impossible. Therefore industrial scale-up is not straightforward at all and requires very high project and investment costs. Now, we have applied a new microwave method enabling the possibility of working without the constraints. The method is safe and cheap, it enables to obtain the utmost efficiency and control also for industrial applications, without resorting to an ordinary oven. We have successfully adopted our procedure for the synthesis “in situ” of ruthenium, palladium and silver nanocatalysts on different supports that present little average diameters, good morphology and very narrow sizes distribution with an absolute reproducibility. The reduction of the metal was also confirmed by XPS measurements. These nanostructured ruthenium catalysts resulted particularly efficient, in terms of activity and selectivity, in different selective catalytic reactions, such as the hydrogenation of benzene to cyclohexene and of phenol to cyclohexanone. The nanostructured palladium nanocatalysts have been employed in the hydrogenation of cyclohexene to cyclohexane and of benzaldehyde to benzyl alcohol and these results are also promising in an industrial perspective
A new, cheap and reproducible microwave mehod for large scale preparation of uniform and efficient nanocatalysts
No full text
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
Fast and Eco–friendly Microwave-Assisted Synthesis of Silver Nanoparticles using Rosemary Essential Oil as Renewable Reducing Agent
Full text linkA green and fast methodology was developed to synthesize silver nanoparticlesusing rosemary essential oil (EO) as a renewable reducing agent. The synthesis process was microwave (MW) assisted, using acoaxialdipole antenna immersed into the reaction medium. This configuration was used to promote both: i) rosemary EO extraction by hydrodistillation, and ii) silver nanoparticle synthesis in an aqueous solution at atmosphericpressure. The effect of two different silver salt substrates and the time reaction on the morphology of the silver nanoparticles was explored. The coaxial microwave assisted hydrodistillation of rosemary yields 0.4%(w/w) in 30 min and contains ethers (17%), ketones (50%) and alcohols (15%). Silver nanoparticles with a tuneable particle size (from 7 to 18 nm) and morphology(from spherical to round-like shapes)were obtained in reaction times ranging from 2to 30 min. The nanoparticle formation was followed b yU V-vis spectroscopy and SEM imaging
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
- …
