1,721,009 research outputs found
Preliminary tests to select operating conditions for the accurate determination of stability constant by cation exchange chromatography: the Cd2+-Cl- and Cd2+-NO3- systems
No full textIon chromatography (IC) has been demonstrated to be a powerful tool for equilibrium constant determination, related to various cation-ligand systems. Nevertheless, no systematic research has been carried out to develop preliminary checks in order to verify whether the variation in ligand concentration in the eluent at constant ionic strength affects the exchange mechanism for the system of interest in the selected chromatographic column. In this paper, tests are proposed which allow one to determine beforehand the experimental conditions to be used in cation-exchange chromatography, whereby parallel mechanisms of elution (mainly in the reversed-phase mode) are avoided. In this way IC becomes an independent rather than an auxiliary means to obtain accurate βi values. Cd(II)Cl- and Cd(II)NO3 - systems were considered and are discussed
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
Simultaneous detection of Escherichia coli O175:H7, Salmonella spp., and Listeria monocytogenes by multiplex PCR
No full textThe wide application of nucleic acid amplification techniques and the increasing industrial interest
toward rapid methods has led to the development and application of PCR based methods for the detection
of microbial pathogens in food. In the present paper we describe the development of a multiplex PCR
method for simultaneous detection of Salmonella enterica serovar Typhimurium, Listeria monocytogenes
and Escherichia coli O157:H7 in a complex food matrix (liquid whole egg).
Four different DNA extraction procedures were evaluated for their application on food and, among
these, Chelex resin combined with a DNA purification step were found to better perform on the food system
considered.
A multiplex PCR system was developed, based on the evaluation and combination of published primer
sets, and applied to the simultaneous detection of the target pathogens plus an internal amplification
control, both in culture media and in a model food system.
The overall system proposed, based on an overnight enrichment step followed by DNA isolation and
multiplex PCR, was satisfactorily tested for its specificity and sensitivity and allowed the detection of
the presence of bacterial DNA and the identification of the target pathogens down to 10 cells/25 g liquid
whole egg
Approccio alla realizzazione di un modello agrometeorologico previsionale della maturazione dello Chardonnay in Franciacorta
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