1,721,018 research outputs found
Temperature control as key factor for optimal biohydrogen production from thermomechanical pulping wastewater
No full textThis study evaluates the use of non-pretreated thermo-mechanical pulping (TMP) wastewater as a potential
substrate for hydrogen production by dark fermentation. Batch incubations were conducted in a
temperature gradient incubator at temperatures ranging from 37 to 80 ◦C, using an inoculum from a thermophilic,
xylose-fed, hydrogen-producing fluidised bed reactor. The aim was to assess the short-term
response of the microbial communities to the different temperatures with respect to both hydrogen yield
and composition of the active microbial community. High throughput sequencing (MiSeq) of the reversely
transcribed 16S rRNA showed that Thermoanaerobacterium sp. dominated the active microbial community
at 70 ◦C, resulting in the highest hydrogen yield of 3.6 (±0.1) mmol H2 g−1 CODtot supplied. Lower
hydrogen yields were obtained at the temperature range from 37 to 65 ◦C, likely due to consumption of
the produced hydrogen by homoacetogenesis. No hydrogen production was detected at temperatures
above 70 ◦C. Thermomechanical pulping wastewaters are released at high temperatures (50–80 ◦C), and
thus dark fermentation at 70 ◦C could be sustained using the heat produced by the pulp and paper plant
itself without any requirement for external heating
Composition and role of the attached and planktonic active microbial community in mesophilic and thermophilic xylose-fed microbial fuel cells
No full textA mesophilic (37 C) and a thermophilic (55 C) two-chamber microbial fuel cell (MFC) were studied and
compared for their power production from xylose and the microbial communities involved. The anodeattached,
membrane-attached, and planktonic microbial communities, and their respective active
subpopulations, were determined by next generation sequencing (Illumina MiSeq), based on the
presence and expression of the 16S rRNA gene. Geobacteraceae accounted for 65% of the anodeattached
active microbial community in the mesophilic MFC, and were associated to electricity
generation likely through direct electron transfer, resulting in the highest power production of
1.1 W m 3. A lower maximum power was generated in the thermophilic MFC (0.2 W m 3), likely due to
limited acetate oxidation and the competition for electrons by hydrogen oxidizing bacteria and
hydrogenotrophic methanogenic archaea. Aerobic microorganisms, detected among the membraneattached
active community in both the mesophilic and thermophilic MFC, likely acted as a barrier for
oxygen flowing from the cathodic chamber through the membrane, favoring the strictly anaerobic
exoelectrogenic microorganisms, but competing with them for xylose and its degradation products. This
study provides novel information on the active microbial communities populating the anodic chamber of
mesophilic and thermophilic xylose-fed MFCs, which may help in developing strategies to favor
exoelectrogenic microorganisms at the expenses of competing microorganisms
Thermophilic versus mesophilic dark fermentation in xylose-fed fluidised bed reactors: Biohydrogen production and active microbial community
No full textDark fermentative biohydrogen production in a thermophilic, xylose-fed (50 mM) fluidised
bed reactor (FBR) was evaluated in the temperature range 55e70 C with 5-degree increments
and compared with a mesophilic FBR operated constantly at 37 C. A significantly
higher (p 1⁄4 0.05) H2 yield was obtained in the thermophilic FBR, which stabilised at about
1.2 mol H2 mol 1 xylose (36% of the theoretical maximum) at 55 and 70 C, and at 0.8 mol
H2 mol 1 xylose at 60 and 65 C, compared to the mesophilic FBR (0.5 mol H2 mol 1 xylose).
High-throughput sequencing of the reverse-transcribed 16S rRNA, done for the first time on
biohydrogen producing reactors, indicated that Thermoanaerobacterium was the prevalent
active microorganism in the thermophilic FBR, regardless of the operating temperature.
The active microbial community in the mesophilic FBR was mainly composed of Clostridium
and Ruminiclostridium at 37 C. Thermophilic dark fermentation was shown to be suitable
for treatment of high temperature, xylose-containing wastewaters, as it resulted in a
higher energy output compared to the mesophilic counterpart
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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