1,720,970 research outputs found
Natural rubber biodegradation by Alternaria alternata and Penicillium chrysogenum isolates
No full textIn the present work, the biodegradation of natural rubber by means of three filamentous fungi, two Alternaria alternata strains (ANR and BNR) and Penicillium chrysogenum, is reported. The biodegradation process has been optimized in Erlenmeyer flasks and then scaled-up in Fernbach flasks. The biodegradation was performed in stationary liquid cultures with biomass immobilized on ceramic Berl saddles. In the presence of NR as the only carbon source, the maximum value of enzyme activity (0.242 IU/L) was reached at 41 days of incubation and at the end of incubation time, 65 days, a 2% weight loss of NR was detected. In Fernbach flasks, the maximum peroxidase activity value was doubled (0.500 IU/L) and reached earlier, after 6 days. In the same incubation time, a better biodegradation performance (4.3%) was obtained. Moreover, the application of a double biodegradation step allowed to obtain higher biodegradation percentage, 6.8%. Among the different tested microorganisms, A. alternata BNR showed the best biodegradation potentiality in terms of enzyme production and NR degradation. On the basis of the results obtained in liquid cultures, A. alternata BNR is currently applied in a lab-scale microcosm study which has to be considered the preliminary step of an in-field biodegradation process
Agar Plate Methods for Assessing the Antibacterial Activity of Thyme and Oregano Essential Oils against S. epidermidis and E. coli
Full text linkThe resistance to antimicrobials (AMR), especially antibiotics, represents a serious problem and, at the same time, a challenge. In the last decade, a growing interest in the use of essential oils (EOs) as antimicrobial substances was observed. Commercial thyme and oregano EOs are reported to be the main responsible of the oil antimicrobial efficacy against both Gram-positive and Gramnegative pathogenic bacteria. The aim of the present work was to study the efficacy of EOs against Staphylococcus epidermidis and Escherichia coli in long-time treatments. In a preliminary microdilution test, a MIC value was obtained for thyme EO against S. epidermidis and E. coli. After that, disk diffusion and disk volatilization tests were set up to study the influence of main cultural parameters on EO activity in liquid or vapor phase. Both bacteria were inhibited by thyme and oregano EOs when applied pure (100% v/v) or diluted (75% and 50% v/v): a higher inhibition was observed in a disk diffusion test in which the antimicrobial effect was due to both liquid and vapor phase components. Finally, a comparison with literature data was carried out even if it was not so easy because standard methods are usually modified and adapted to specific case study. For this reason, the results have to be interpreted in relation to the analytical method applied
Characterization of confectionary products containing chocolate and hazelnuts
No full textThe analysis of numerous conched chocolate samples and roasted hazelnuts has allowed to point out the fundamental aromatic constituents and to undertake a chemical interpretation of the final product taste. It has been experienced that the concentrations of these constituents, also those unpleasant, in the raw materials can be controlled by means of the thermal operations condition
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
On the effect of freeze-drying on paper-borne microorganisms
Full text linkToday there is an ever-increasing interest in recovering flooded archival materials. Freeze-drying stands out as a valuable method as the water is frozen and the ice is then removed through sublimation. The present work is focused on the effect of freeze-drying on flooded paper contaminated with biodeteriogenic microorganisms (i.e. a bacterium Staphylococcus epidermidis, a yeast Rhodotorula mucilaginosa and a filamentous fungus Alternaria alternata). The effect of freezing and drying on microorganism survival and growth has been separately evaluated. In particular, different operative conditions for freezing (in a domestic freezer at about -20°C, at -40°C with a freezing rate of -1°C/min) and drying (200 μbar at 0°C and 20°C) have been tested. All the tested strains were able to survive after freezing and drying phases, nevertheless a different behaviour was observed: the growth of S. epidermidis was the same as that of the control, R. mucilaginosa showed a slight growth and carotenoid production increase, while A. alternata was inhibited, in particular after the freezing at -40°C, followed by a low temperature drying rate step
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
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