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Effects of surfactants on the stabilization of the bovine lactoperoxidase activity
No full textBovine lactoperoxidase (LPO) is taken as a model protein of mammalian peroxidases
to investigate the activity and the stability of the enzyme in the presence of different surfactants. The cationic benzalkonium chloride (Bz) has proved efficient in preserving
the enzymatic activity for over 10 days, while the native enzyme completely lost its activity within 3-4 days. The presence of Bz allows the enzyme to preserve its
secondary structure for a long time, as shown in CD spectra, and creates a more
hydrophobic environment for the enzyme, as indicated in fluorescence studies.
Moreover, this surfactant at a concentration of 0.01% (0.3 mM) increases the lactoperoxidase activity in the first 2 h of incubation at 37 °C. Both hydrophobic and
electrostatic interactions of the cationic surfactant seem to be responsible for the
enzyme activation and stabilization, and this is a promising result in view of industrial applications of enzymes
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
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