1,720,958 research outputs found
Hydrogen production dynamic during cheese whey Dark Fermentation: New insights from modelization
No full textThe modelization of non methanogenic anaerobic environments can be particularly challenging owing to the variability of the metabolic products. In particular, both hydrogen production and consumption take place at the same time due to the simultaneous occurrence of Dark Fermentation (DF) and homoacetogenis. The goal of this study is to investigate the kinetic and thermodynamic aspects of the biochemical pathways involved in the fermentation of ultrafiltered cheese whey; to this aim, a continuous digester was operated under three different Hydraulic Retention Times (6, 9 and 12 h) and fixed pH (5.5). A mathematical model, based on a variable stoichiometry approach, was implemented and calibrated; the proposed model allowed the determination of the parameters governing the most relevant pathways, namely homoacetogenesis and butyric and ethanol-type DF. A special focus was given to the quantification of the hydrogen turnover rate; the model proved to be an effective tool, in addition to widely adopted techniques such as microbial and isotopic analysis, for obtaining a deeper comprehension of the crucial aspects governing the non-methanogenic process
Dark Fermentation of de-proteinized cheese whey: is nitrogen a key factor for process stability?
No full textEffetto dell'HRT e della concentrazione in alimento sulla produzione di idrogeno per dark fermentation in reattore continuo
Full text linkLAUREA MAGISTRALEL’oggetto della presente tesi è lo studio della produzione di idrogeno attraverso dark fermentation del siero di latte e della sua ottimizzazione, all’interno di un reattore CSTR alimentato in continuo, su scala pilota. La produzione è stata monitorata mantenendo una temperatura di 36 °C e un pH di 5,5 e variando alcuni parametri di processo, quali il tempo di ritenzione idraulica (HRT) e la concentrazione di COD nell’alimento al reattore, con l’obiettivo di ottenere delle condizioni stabili e di determinare le migliori condizioni operative relativamente a questa tipologia di processo. Si è operato dapprima con concentrazione costante in ingresso di 30 gCOD/L e variando l’HRT (12 h, 6 h, 9 h). Dopodiché si è operato con un HRT costante di 9 h e si sono variate le concentrazioni di COD alimentate (20 gCOD/L, 10 gCOD/L). Si sono conseguite le migliori prestazioni operando con un HRT di 9 h e una concentrazione di COD in ingresso di 10 gCOD/L: le rese ottenute in condizioni stabili sono sempre state superiori a 2,8 molH2/mollattosio, con un massimo di 3,47 molH2/mollattosio.The topic of this thesis is the study of hydrogen production through dark fermentation of cheese whey and its optimization, within a CSTR reactor fed continuously, on a pilot scale. The production was monitored by maintaining a temperature of 36 ° C and a pH of 5.5 and varying certain process parameters, such as the hydraulic retention time (HRT) and the COD concentration in the feed to the reactor, with the aim to obtain stable conditions and to determine the best operating conditions with respect to this type of process. It was operated first with constant input concentration of 30 gCOD/L and varying the HRT (12 h, 6 h, 9 h). After that it has been operated with a constant HRT of 9 h and varying the concentrations of COD fed (20 gCOD/L, 10 gCOD/L). The best performance has been achieved by operating with a HRT of 9 h and a COD concentration at the entrance of 10 gCOD/L: the yields obtained in stable conditions have always been above 2.8 molH2/mollactose and the maximum value was 3 , 47 molH2/mollactose
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
