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Multivariate quantification of spectroscopic interferences caused by sodium, calcium, chlorine and sulphur in inductively coupled plasma mass spectrometry
No full textStudio della speciazione di metallo-ioni in acqua di mare tramite titolazione con resina e linearizzazione di Ruzic
No full textDetermination of metal ions concentration and speciation in seawater by titration with an iminodiacetic resin.
No full textAchelating resin containing iminodiacetic groups, Chelex 100 which is often employed for sorbing metal ions from complex
matrices, was used for separating and preconcentrating heavy metal ions from seawater samples. The resin titration method
was applied for determining the total concentration. The experimental procedure consists of measuring the concentration of
the metal sorbed on Chelex 100 from solutions with different ratios volume of aqueous phase/amount of resin. The total metal
ion concentration is obtained from the experimental data by a model for the sorption on the resin, the parameters of which
are obtained by a non-linear regression procedure. In this way not only the total metal ion concentration can be determined,
but also the side reaction coefficient M.I/, if the sorption equilibria of the considered metal ion on the resin are exactly
known, as is the case of Chelex 100 considered here. The resin titration with Chelex 100 was utilized for determining the total
metal ion concentration in certified seawater samples and real samples from the Ligurian Sea. It allowed the simultaneous
determination of the total concentration of manganese(II), cadmium(II), nickel(II) and copper(II), in acceptable agreement
with the certified values. Moreover, the side reaction coefficients of some complex species could be evaluated. They were
very high, and strongly dependent on the acidity of the sample solution. For instance, values varying from 109 to 1011 were
obtained for copper (II) in the different samples considered, at pH around 7. Chelex 100 is such a strong sorbing substance
that it is able to compete with the stable complexes for the combination with the heavy metal ions considered here
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
Determination of manganese by graphite furnace atomic absorption spectrometry: matrix effect control by multiple linear regression model
No full textDispelling 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
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