1,720,960 research outputs found
Molecular characterization and methane performances of archaea in anaerobic batch reactors feed with giant reed, a new promising feedstock
No full textAgroindustrial residues and energy crops for the production of hydrogen and poly-β-hydroxybutyrate via photofermentation
No full textThe present study was aimed at assessing the biotransformation of dark fermented agroindustrial residues and energy crops for the production of hydrogen and poly-β-hydroxybutyrate (PHB), in lab-scale photofermentation. The investigation on novel substrates for photofermentation is needed in order to enlarge the range of sustainable feedstocks. Dark fermentation effluents of ensiled maize, ensiled giant reed, ensiled olive pomace, and wheat bran were inoculated with Rhodopseudomonas palustris CGA676, a mutant strain suitable for hydrogen production in ammonium-rich media. The highest hydrogen producing performances were observed in wheat bran and maize effluents (648.6 and 320.3 mL L-1, respectively), both characterized by high initial volatile fatty acids (VFAs) concentrations. Giant reed and olive pomace effluents led to poor hydrogen production due to low initial VFAs concentrations, as the original substrates are rich in fiber. The highest PHB content was accumulated in olive pomace effluent (11.53%TS), ascribable to magnesium deficiency
Energy conversion of biomass crops and agroindustrial residues by combined biohydrogen/biomethane system and anaerobic digestion
No full textAim of this study was to evaluate the suitability of ensiled giant reed, ensiled maize, ensiled olive pomace,
wheat bran for combined systems (CS: dark fermentation + anaerobic digestion (AD)) producing
hydrogen-rich biogas (biohythane), tested in batch under basic operational conditions (mesophilic temperatures,
no pH control). Substrates were also analyzed under a single stage AD batch test, in order to
investigate the effects of DF on estimated energy recovery (ER) in combined systems. In CS, maize and
wheat bran exhibited the highest hydrogen potential (13.8 and 18.9 NL kgVS1) and wheat bran the highest
methane potential (243.5 NL kgVS1). In one-stage AD, giant reed, maize and wheat bran showed the
highest methane production (239.5, 267.3 and 260.0 NL kgVS1). Butyrate/acetate ratio properly
described the dark fermentation, correlating with hydrogen production (r = 0.92). Wheat bran proved
to be a promising residue for CS in terms of hydrogen/methane potential and ER
Anaerobic digestion and Co-digestion of oleaginous Microalgae residues for biogas production
Full text linkMicroalgae have been suggested as one of the most promising feedstock for the production of bioenergy and biofuels, including biodiesel and aviation fuels, because of the high oil content of selected species. In the context of biofuel production from microalgae, anaerobic digestion of microalgal biomass residues after oil extraction has the potential to make the process more sustainable and increase the energy efficiency. The main goal of this study was to assess microalgae residues as substrates for anaerobic digestion and investigate their potential for biomethane production. Biochemical Methane Potential (BMP) tests were carried out on a microalgal species, Nannochloropsis gaditana, selected for its high oil content and fast growth rate. The methane potentials observed for the microalgae residue after lipid extraction were higher than those recorded for the raw microalgae samples. Co-digestion with cellulose did not clearly enhance the anaerobic digestion performances
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
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