1,721,034 research outputs found
Fast Optical Sensing of Metals: A Case Study of Cu2+ Assessment in Soils
No full textIn this paper we report an application of a novel porphyrin ligand, Zn(II)TPP-BPI-crown (ZnPC), functionalized with two dibenzo-crown-ether moieties as cation-sensitive ionophore. The test on the optical response of ZnPC ligand inside PVC-based polymeric membranes towards different cations (Na+, K+, Li+, Ca2+, Mg2+, Co2+, Cd2+, Pb2+, Zn2+, Cu2+ and NH4+) were performed. The influence of the lipophilic site functionalization on the ZnPC optode response was investigated. The visibly (naked eye) observed color change of sensing material from green to red demonstrated the suitability of the ZnPC-based optodes to perform fast monitoring of Cu(II) ions in the concentration range between 6.6 × 10-7 and 2.4 × 10-2 mol l-1, with a low detection limit (estimated by s/n = 3 method) of 0.03 mg l-1, which is lower than WHO guideline value of 2 mg l-1 for natural waters. The membranes with the best composition were deposited onto paper support and employed for the express analysis of copper(II) ion in aqueous soil extracts. The results obtained were in a good agreement with a standard ASS method, thus suggesting the utility of developed sensors for aims of express environmental monitoring
Chapter 5: Peroxo-vanadium Complexes as Sustainable Catalysts in Oxidations, Halogenations and Other Organic Transformations
No full textVanadium in its high-oxidation state can activate hydrogen peroxide and other alkyl hydroperoxides, generating highly active oxidising species, namely vanadium peroxido-complexes. Several studies have been performed to deeply investigate structural features and reactivity of such species. In this chapter, the application of V-peroxido-complexes in oxidation and halogenation reactions will be discussed. Specifically, oxidation of different hydrocarbon substrates (i.e., alkanes, alkenes, aromatics), alcohols, phenols and sulphides, as well as the catalytic bromination reaction of diverse organic substrates will be addressed. Notably, vanadium peroxido-complexes result in effective catalysts to perform these transformations in very mild conditions. Importantly, the feasibility of the proposed procedures on a large scale allows their exploitation for appealing applicative purposes. Examples of lignin valorisation, fuel desulfurization, as well as clean synthetic methodologies for developing interesting building blocks for synthetic, industrial and pharmaceutic applications will be summarised
Chemoresistivity of solid state layers of porphyrin nanotubes
No full textPorphyrins are versatile molecules that can serve as sensitive materials in many different kinds of chemical sensors. These properties greatly enhance when porphyrins are aggregated in nanostructured molecular assemblies. Among such structures, nanotubes are particularly interesting. In particular, the superior sensitivity of nanotubes was previously demonstrated with optical sensors. In this paper, we describe a nanotubular structure that enhances the porphyrin conductivity enabling the fabrication of porphyrin based chemoresistances. © 2011 IEEE
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
Modulating electron transfer in ferrocene-naphthoquinone dyads: new insights in parameters influencing ET efficiency
No full textVariations 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
Demetalation of corrole complexes: an old dream turning into reality
No full textDifferent strategies for the demetalation of corrole complexes have been developed, using copper complexes of corrole as model compounds.,Best results were obtained using the acidic mixture CHCl3/H2SO,, which allowed the almost complete removal of copper ions from both mesotriaryl-, beta-octaalkyl- and fully substituted corroles. This route reduced both the decomposition of the starting complex and the formation of isocorrole species produced by oxidation of the corrole ring in the acidic conditions necessary for the demetalation reaction. To investigate the scope of the reaction, the same approach was later extended to other metal complexes of corrole, such as cobalt, manganese, iron and germanium derivatives. Although not always successful, this approach demonstrated that in the case of corrole it is also possible to obtain a reversible coordination of metal ions, a route of synthetic interest for further functionalization of the corrole ring. Copyright (c) 2008 Society of Porphyrins & Phthalocyanines
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
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