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Production of ethanol with Saccharomyces cerevisiae in a continuous reactor. Note I: kinetics of immobilized yeast
No full textContinuous production of ethanol by fermentation with immobilized yeasts gives a better yield and capacity and can be better controlled than conventional processes with batch reactors and a suspended biomass. This paper (the first of three) examines the operative conditions for immobilizing Saccharomyces Cerevisiae on beech wood cubes. After preliminary evaluation of the non-influence of mass transfer phenomena and the extent of alcoholic inhibition, an experimental investigation of the kinetics for a metabolic reaction in a continuous recycle reactor was carried out. The kinetic equation was found to be a Michaelis-Menten type with uncompetitive inhibition by substrate, and linear inhibition by product
Production of ethanol with Saccharomyces cerevisiae in a continuous reactor. Note III: an experimental, kinetic study with suspended, recycled biomass
No full textBy way of comparison with the kinetic investigation of the continuous production of ethanol in a tubular reactor with immobilized yeasts, a study was carried out of continuous fermentation in a stirred reactor, with final separation and recycling of the microorganisms. Flocculation with potassium ferrocyanide and zinc sulphate was used to separate the biomass. The maintenance of the metabolic activity was assessed. Next, discontinuous fermentation at various substrate and biomass concentrations was performed to determine the kinetics of glucose-ethanol transformation by flocculated and reinoculated Saccharomyces Cerevisiae. Once again, the kinetic expression was a Michaelis-Menten equation, with un-competitive inhibition of the substrate and linear inhibition of the product. The values observed for the various parameters were not very different from those for a biomass immobilized on an inert support or for a free biomass. Finally, the productivities of several types of reactor are compared
Production of ethanol with Saccharomyces cerevisiae in a continuous reactor. Note II: test and modeling for a packed tubular reactor with immobilized yeast
No full textThe biochemical production of ethanol has been studied in a packed tubular reactor with Saccharomyces Cerevisiae immobilized on wooden cubes. The kinetics of the reaction was described in a previous paper. The experimental axial profiles for the substrate and product concentrations are compared with those calculated from a reactor model obtained by introducing the biochemical kinetic expression in the design equations. A good fit between the experimental and the calculated values could only be obtained by including a biological efficiency coefficient. The reactor was kept in operation for 28 days to assess its technological reliability. It was found to be biologically stable. Its productivity was constant and comparable to that reported in the literature for similar reactors
Impact Assessment on the Environment for the Cement Industry. Influence of the Production Cycle
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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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