1,720,961 research outputs found
Light-Induced Organic Transformations by Covalent Organic Frameworks as Reticular Platforms for Selective Photosynthesis
Full text linkPhotoassisted synthesis of value-added organic products has developed greatly in the last decades in response to the pressing need for a transition toward sustainable processes and renewable energy. One of the formidable challenges of the light-induced chemical steps is provided by the control of the catalytic efficiency and selectivity under photocatalytic conditions. An attractive perspective is foreseen by triggering the photoreaction events in confined spaces, wherein light harvesting and photocatalytic units are framed into functional architectures. Division of tasks among specialized compartments responds to a bioinspired strategy with the final aim to orchestrate the rate of concurrent and sequential events, to maximize performance while directing the reaction selectivity. Covalent organic frameworks (COFs) are a class of emerging materials that can meet these requirements, with the potential to bridge the existing gap between molecular and heterogeneous photocatalysis. Here, a rich pool of molecular building blocks and chemical linkages is available to afford crystalline porous solids with tailored photophysical properties emerging from the interconnected COF structure walls, while catalytic cofactors can be provided by engineering of the pore surface. In this Perspective, we highlight recent developments where COFs have been successfully employed as photocatalysts for selective organic transformations. The relationship between the COF reticular structure and its photocatalytic behavior is discussed, in terms of the light-conversion pathways and photoredox events, including electron and/or energy transfer mechanisms. The possible role of confinement effects, intrinsic in long-range order porous COF materials, remains largely unexplored in photocatalytic applications. New progress is expected to arise from close interdisciplinary cooperation involving synthetic chemistry and materials science communities
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
An advection-diffusion-reaction model for coffee percolation
No full textAdvection-diffusion-reaction equations are largely exploited in applied science, for their ability to describe real-life phenomena where mass transport and diffusion, as well as chemical reactions, occur. Here, these models are used to describe the percolation phenomena arising in espresso coffee extraction. The resulting initial/boundary value problem is solved using the Crank-Nicolson scheme and a nested fixed-point iteration. Mass conservation and positivity of the solution are guaranteed. The reliability of the model together with the proposed solving strategy is assessed experimentally, by comparing the efficiency of real and simulated extractions conducted under different physico-chemical conditions
Computer Percolation Models for Espresso Coffee: State of the Art, Results and Future Perspectives
Full text linkCoffee is one of the most consumed beverages in the world. This has two main consequences: a high level of competitiveness among the players operating in the sector and an increasing pressure from the supply chain on the environment. These two aspects have to be supported by scientific research to foster innovation and reduce the negative impact of the coffee market on the environment. In this paper, we describe a mathematical model for espresso coffee extraction that is able to predict the chemical characterisation of the coffee in the cup. Such a model has been tested through a wide campaign of chemical laboratory analyses on espresso coffee samples extracted under different conditions. The results of such laboratory analyses are compared with the simulation results obtained using the aforementioned model. The comparison shows a close agreement between the real and in silico extractions, revealing that the model is a very promising scientific tool to take on the challenges of the coffee market
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
- …
