1,720,973 research outputs found
Applications of nanomaterials in potentiometric sensors
No full textNanomaterials play an important role in the fabrication of chemosensors and biosensors, due to their unique physical and chemical properties, such as large surface area/volume ratio, good conductivity, excellent electrocatalytic activity and high mechanical strength. We review recent advances in the applications of these nanomaterials in potentiometric sensors. We highlight the development of stable solidstate polymeric membrane ion-selective electrodes (ISEs). We describe ISEs based on ionophore-modified nanomaterials. Also, we present highly-sensitive potentiometric biosensors based on nanomaterials. (C) 2013 Elsevier Ltd. All rights reserved.Nanomaterials play an important role in the fabrication of chemosensors and biosensors, due to their unique physical and chemical properties, such as large surface area/volume ratio, good conductivity, excellent electrocatalytic activity and high mechanical strength. We review recent advances in the applications of these nanomaterials in potentiometric sensors. We highlight the development of stable solidstate polymeric membrane ion-selective electrodes (ISEs). We describe ISEs based on ionophore-modified nanomaterials. Also, we present highly-sensitive potentiometric biosensors based on nanomaterials. (C) 2013 Elsevier Ltd. All rights reserved
Potentiometric measurement of ascorbate by using a solvent polymeric membrane electrode
No full textA novel potentiometric method for the determination of ascorbate is described in this communication. It is based on ascorbate oxidation with permanganate which is continuously released from the inner reference solution of a ligand-free tridodecylmethyl ammonium chloride (TDMAC)-based polymeric membrane ion selective electrode (ISE). The ISE potential determined by the activity of permanganate ions released at the sample-membrane phase boundary is increased with the consumption of permanganate. The proposed membrane electrode is useful for continuous and reversible detection of ascorbate at concentrations in 0.1 M NaCl ranging from 1.0 x 10(-6) to 1.0 x 10(-3) M with a detection limit of 2.2 x 10(-7) M. (C) 2007 Elsevier B.V. All rights reserved
A solid-contact Pb2+-selective polymeric membrane electrode with Nafion-doped poly(pyrrole) as ion-to-electron transducer
No full textConducting polymer poly(pyrrole) (PPy) doped with Nafion was successfully used as ion-to-electron transducer in the construction of a solid-contact Pb2+-selective polymeric membrane electrode. The Nafion dopant can effectively increase the capacitance of the conducting polymer and improve the mechanical robustness of the coating. The transducer layer, PPy-Nafion, characterized by cyclic voltammetry and electrochemical impedance spectroscopy, exhibits a sufficiently high bulk (redox) capacitance and fast ion and electron transport process. The new Pb2+-selective polymeric membrane electrode, based on PPyNafion film as solid contact, shows stable Nernstian characteristics in Pb(NO3)(2) solution within the concentration range of 1.0 x 10(-7)-1.0 x 10(-3) M, and the detection limit is 4.3 x 10(-8) M. The potential stability of the electrode and the influence of the interfacial water layer were also evaluated by chronopotentiometry and potentiometric water layer test, respectively. The results show that the solid-contact Pb2+-selective electrode, based on PPy-Nafion film as ion-toelectron transducer, can effectively overcome the potential drift and reduce the water layer between the PPy-Nafion transducer layer and the ion-selective membrane
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
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
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