1,720,967 research outputs found
Bioethanol production from mixed sugars by Scheffersomyces stipitis free and immobilized cells, and co-cultures with Saccharomyces cerevisiae
No full textBioethanol can be produced from several biomasses including lignocellulosic materials. Besides 6-carbon sugars that represent the prevalent carbohydrates, some of these feedstocks contain significant amounts of 5-carbon sugars. One common limit of the major part of the xylose-fermenting yeasts is the diauxic shift between the uptake of glucose and xylose during the fermentation of mixed syrups. Thus, optimized fermentation strategies are required.In this paper the ability of Scheffersomyces stipitis strain NRRLY-11544 to ferment mixed syrups with a total sugar concentration in the range 40-80. g/L was investigated by using mono cultures, co-cultures with Saccharomyces cerevisiae strain Bakers Yeast Type II and single cultures immobilized in silica-hydrogel films. The experimental design for the fermentations with immobilized cells included the process analysis in function of two parameters: the fraction of the gel in the broth and the concentration of the cells loaded in the gel. Furthermore, for each total sugars level, the fermentative course of S. stipitis was analyzed at several glucose-to xylose ratios.The results indicated that the use of S. stipitis and S. cerevisiae in free co-cultures ensured faster processes than single cultures of S. stipitis either free or immobilized. However, the rapid production of ethanol by S. cerevisiae inhibited S. stipitis and caused a stuck of the process.Immobilization of S. stipitis in silica-hydrogel increased the relative consumption rate of xylose-to-glucose by 2-6 times depending on the composition of the fermentation medium. Furthermore the films performances appeared stable over three weeks of continuous operations. However, on the whole, the final process yields obtained with the immobilized cells were not meaningfully different from that of the free cells. This was probably due to concurrent fermentations operated by the cells released in the broth. Optimization of the carrier characteristics could improve the performances of the process with immobilized cells. © 2013 Elsevier B.V
Sottoprodotti dell'industria di trasformazione del pomodoro e tecnologie per la loro valorizzazione
Full text linkA livello mondiale l’Italia è il secondo produttore di pomodoro da industria dopo gli Stati Uniti, seguita dalla Cina. Questi tre paesi coprono circa il 60% della produzione totale a livello europeo, l'Italia risulta il primo produttore, seguito da Spagna, Turchia e Portogallo.Nell’ambito dell’area mediterranea, l’Italia svolge un ruolo di primaria importanza nella produzione di trasformati del pomodoro, con il 14% della produzione complessiva e il 48% di quella europea, con un fatturato di oltre 3,2 miliardi di €. La filiera nazionale del pomodoro da industria è organizzata in due Distretti, quello del nord e quellodel centro-sud, con Emilia-Romagna e Puglia che rappresentano le regioni con maggiore produzione. Sono stati analizzati i dati relativi alla superficie coltivata a pomodori da industria, alla produzione totale e a quella raccolta, i dati di import ed export e le varie fasi di trasformazione industriale per ottenere derivati, quali polpa, pelati, concentrati, pomodorini e sughi. Il processo di trasformazione del pomodoro, inevitabilmente, comporta degli sprechi di diversa origine, rappresentati dai pomodori non idonei alla trasformazione industriale, dall’acqua utilizzata nei processi di lavorazione e dagli scarti dovuti ai prodotti secondari (buccette, semi). E’ stato analizzato il recupero e il riuso di questi sottoprodotti, nell’ottica dell’economia circolare, ai fini della razionalizzazione dei costi del processo produttivo e dei costi per lo smaltimento degli scarti. Nel rapporto sono descritti e analizzati i processi di valorizzazione energetica dei sottoprodotti, quali la digestione anaerobica, la torrefazione e la cella microbica, in grado di produrre energia elettrica e termica da utilizzare nello stesso ciclo di trasformazione, ma da immettere anche in rete.Da buccette e semi si possono ottenere lacche ecologiche, utilizzate come rivestimento del packaging alimentare metallico, materiali biodegradabili (buste di plastica, teli per la copertura delle serre o dei campi), composti bioattivi antiossidanti (licopene e β-carotene), utilizzati come integratori alimentari, mangimi per zootecnia e compost. Infine, le acque reflue, attraverso un processo di separazione a membrana, possono essere filtrate e riutilizzate nel processo di lavorazione del pomodoro e per l’irrigazione della coltura stessa.Italy is second producer of tomatoes for industrial use in the world, behind USA and followed by China. All together they cover about 60% of total production. Italy is the leader in Europe, followed by Spain, Turkey and Portugal. In the Mediterranean area, Italy plays a major role for the tomato derivatives production, with 14% of the total production and 48% of the European one, with a invoiced of over 3.2 milliard €. The national supply chain of industrial tomato is organized in two Districts, the Northern and Central-South one, where Emilia-Romagna and Apulian are the Regions with the higher production. Data about cultivated area with tomatoes for industry (he), total production (ton) and harvested production (ton), import and export, the various phases of industrial transformation to obtain derivatives, such as tomato pulp, peeled tomatoes, tomato concentrates, cherry tomatoes, and sauces were analysed. The tomatoes transformation processes produce waste of different origin, such as unsuitable tomatoes for industrial processing, the water used in the line production and waste due to the secondary products (peel tomatoes, seed). The recovery and reuse of these by-products, considered in a concept of circular economy, were analysed. These allow to rationalize and manage costs for transformation processes and to contain these for disposal of waste. Specifically, same of the energetic valorisation processes of the by-products were described. The anaerobic digestion process, the roasting process and microbial cell to produce electric and thermic energy.This energy can be used in the same transformation cycle and also entered into power grid. Eco-paint, used as a coating for metallic food packaging, biodegradable materials, as plastic bags, sheets for covering greenhouses or fields, bioactive antioxidant compounds, such as lycopene and β-carotene, used as alimentary integrator, animal feed and compost can be obtained from tomatoes byproducts. The waste water, at least, by membrane separation process, can be filtered and re-used in the tomato industry and for irrigation
Integrated treatments of steam explosion and enzymatic hydrolysis to produce energetic and industrial products from lignocellulosic biomasses
No full textBioethanol production from steam-pretreated corn stover through an isomerase mediated process
No full textAgricultural by-products such as corn stover are considered strategic raw materials for the production of second-generation bioethanol from renewable and non-food sources. This paper describes the conversion of steam-pretreated corn stover to ethanol utilising a multi-step process including enzymatic hydrolysis, isomerisation, and fermentation of mixed hydrolysates with native Saccharomyces cerevisiae. An immobilised isomerase enzyme was used for the xylose isomerisation along with high concentrations of S. cerevisiae. The objective was to assess the extent of simultaneity of the various conversion steps, through a detailed analysis of process time courses, and to test this process scheme for the conversion of lignocellulosic hydrolysates containing several inhibitors of the isomerase enzyme (e.g. metal ions, xylitol and glycerol).The process was tested on two types of hydrolysate after acid-catalysed steam pretreatment: (a) the water soluble fraction (WSF) in which xylose was the largest carbon source and (b) the entire slurry, containing both cellulose and hemicellulose carbohydrates, in which glucose predominated.The results indicated that the ethanol concentration rose when the inoculum concentration was increased in the range 10-75g/L. However, when xylose was the largest carbon source, the metabolic yields were higher than 0.51gethanol/gconsumed sugars probably due to the use of yeast internal cellular resources. This phenomenon was not observed in the fermentation of mixed hydrolysates obtained from the entire pretreated product and in which glucose was the largest carbon source. The ethanol yield from biomass suspensions with dry matter (DM) concentrations of 11-12% (w/v) was 70% based on total sugars (glucose, xylose, galactose). The results suggest that xylulose uptake was more effective in mixed hydrolysates containing glucose levels similar to, or higher than, xylose.Analysis of the factors that limit isomerase activity in lignocellulosic hydrolysates excluded any inhibition due to residual calcium ions after the detoxification of the hemicellulose hydrolysates with Ca(OH)2. By contrast, most of the enzyme activity ceased during the fermentation of the entire slurry after steam explosion, probably due to synergistic inhibition effects of various fermentation co-products. © 2014 Elsevier B.V
Metodiche comparative per la determinazione del consumo trofico in detritivori marini: Motodo ponderale vs. emivita 32P.
No full textIntegrated treatment of steam explosion and enzymatic hydrolysis to produce energetic and industrial products from lignocellulosic biomass.
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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
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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