1,720,960 research outputs found
Resuspended freeze-dried Nannochloropsis as a model laboratory system for concentrated fresh Nannochloropsis in ultrasound cell disruption experiments
No full textMicroalgae have rigid, complex cell walls hindering direct lipid extraction. Cell disruption techniques are used to rupture these cellular structures to increase lipid extraction. Researchers investigating the downstream processing of microalgae do not always have access to microalgal cultivation systems to generate large amounts of fresh microalgal biomass. Using resuspended freeze-dried microalgal biomass as a model laboratory system for concentrated fresh biomass during cell disruption experiments offers greater flexibility in experimental planning and omits investment costs of microalgal cultivation equipment. So far, it however remains unclear whether freeze-dried resuspended biomass can be used as a model laboratory system to represent concentrated fresh biomass during cell disruption and lipid extraction experiments. This paper thus evaluated the suitability of resuspended freeze-dried Nannochloropsis as a model laboratory system for concentrated fresh Nannochloropsis during cell disruption. Ultrasound assisted cell disruption was used as example cell disruption technique and lipid extraction efficiency and free fatty acid content were investigated. Tap water and 3% sodium chloride are both suitable resuspension media for the resuspension of freeze-dried Nannochloropsis. Resuspension duration should be limited (< 120 min) to prevent the formation of free fatty acids. The condition of the biomass (concentrated fresh, or resuspended freeze-dried) prior to ultrasound assisted cell disruption did not influence the resulting lipid extraction efficiency. Resuspended freeze-dried Nannochloropsis biomass in tap water or 3% sodium chloride can thus be used as a model laboratory system for fresh microalgal biomass during research on ultrasound assisted lipid extraction. The generalization of the results to other cultivation conditions, cell disruption techniques, components of interest or microalgal species should be carefully assessed.The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported by Flanders’ Food and funded by Flanders Innovation and Entrepreneurship (VLAIO) through the cSBR
project EffSep (Grant number HBC.2019.0012)
Ultrasound assisted extraction of Nannochloropsis: Effects on lipid extraction efficiency and lipid stability
No full textUltrasound assisted extraction of microalgal lipids from Nannochloropsis in presence of hexane/isopropanol extraction solvent was studied. The results were compared with adequate control extractions, using the same solvent system, solvent contact time and extraction temperature but in the absence of ultrasound. Ultrasound assisted extraction at 0.45 W/mL and control extractions at elevated temperatures (comparable to the temperature induced by the ultrasound) resulted in similar lipid, free fatty acid and pigment extraction efficiencies and the free fatty acid and pigment content of the lipid extracts was comparable. The control and ultrasound assisted extractions did not influence the lipolytic and oxidative stability of the lipids during extraction. These results indicated that the positive impact of ultrasound assisted extraction can almost completely be attributed to the ultrasound induced increased temperature. Simpler extraction techniques applying moderate heating (+/- 40 degrees C) in presence of lipid extraction solvents are most probably more straightforward to implement industrially compared to ultrasound assisted extraction.The authors want to thank VLAIO and Flanders' FOOD for their funding and support during the EffSep Project [c-SBO project HBC.2019.0012]. The authors wish to thank Dr. Jonas Blockx for proofreading the paper. The authors also wish to thank C´eline Dejonghe for integrating part of the FAME chromatograms
Enzyme-assisted disruption of oleaginous microalgae to increase the extraction of lipids: Nannochloropsis as a case study
No full textsponsorship: Acknowledgements This work was supported by the EffSep project. The EffSep project is financed by the Vlaams Agentschap Innoveren en Ondernemen (VLAIO) of Belgium (grand ID: c-SBO project HBC.2019.0012) . The authors also wish to thank Flanders' Food for their support. The authors sincerely thank Dr. Elaine Kozma for revising the language of the paper. (Vlaams Agentschap Innoveren en Ondernemen (VLAIO) of Belgium|HBC.2019.0012)status: Publishe
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
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