1,720,954 research outputs found
Screening of biomass residue streams for their applicability as feedstocks for activated carbon production and their compliance as electrode material
No full textCurrently, activated carbon production still relies heavily on unsustainable feedstocks, e.g., coal or fresh wood. To be able to phase out these practices, biomass residue streams offer a valid alternative, both from an economic and ecological perspective. Therefore, this research screens different promising biomass streams for their potential to be converted into top-tier activated carbon. These should preferably have a well-developed porosity and high nitrogen content to maximize their energy storage capacity and potential applicability as electrode material in supercapacitors.
Seven different types of biomass were selected in this study based on their physicochemical characteristics (e.g., lignocellulosic composition and nitrogen content): Common ivy trimmings (CI), brewer’s spent grain (BSG), Macadamia nut shells (MNS), chicken feathers (CF), coffee husks (CH) and the microalgae species Spirulina sp. (SP) and Chlorella vulgaris (CV). The biomass streams were transformed into biochars and activated carbons using a home-built stainless steel screw reactor [1,2]. Activated carbon was produced in a two step-process comprising a carbonization step at 700 °C in an inert atmosphere, followed by a physical activation step using CO2 at 800 °C. Biomass, biochars, and activated carbon were characterized for their ultimate and proximate analysis, biochemical composition, and elemental composition via inductively coupled plasma–atomic emission spectroscopy. Their surface functional groups were determined via FT-IR. Lastly, the porosity of the resulting activated carbons was measured via nitrogen physisorption experiments. The most promising activated carbons were incorporated in coin cell supercapacitors.
The results demonstrate the significant impact of the biomass’s mineral composition on creating highly porous activated carbon structures. Furthermore, the overall activated carbon yields decreased for the samples with large ash fractions due to a relative increase in carbon burn-off. In terms of creating nitrogen-rich activated carbons, CF proved best with a resulting nitrogen content of 8.2%, in contrast with MNS, which exhibited the lowest percentage (0.54 %). However, in terms of porosity, this sample (MNS) outperformed the other investigated biomass streams with a BET specific surface area of 693.7 m2/g. A correlation between the activated carbon’s porosity and their specific capacitance could be made when verifying the electrode material performance. Thus, the MNS-derived activated carbon performed best of the screened biomass streams with a specific capacitance of 53 F/g.
In conclusion, an investigation on the screening of different biomass residue streams was performed. It became clear that the low-ash content, lignocellulosic biomass MNS performed best compared to the other tested biomass streams. Future research should focus on combining different biomass streams to produce a highly porous nitrogen-rich biomass stream that would be perfectly suitable as electrode material
Biomass Residue Streams as Potential Feedstocks for the Production of Activated-Carbon-Based Electrodes for Supercapacitors
No full textCurrently, activated carbon production relies heavily on unsustainable feedstocks, e.g., coal and fresh wood. To phase out these practices, biomass residue streams offer a valid alternative. Therefore, this research screens different biomass streams to be converted into top-tier activated carbon. These should preferably have a well-developed porosity and high nitrogen content to maximize their potential as electrode materials in supercapacitors. Seven different biomass streams were selected in this study: common ivy trimmings (CI), brewer’s spent grain (BSG), macadamia nut shells (MNS), chicken feathers (CF), coffee husks (CH), and the microalgae species Spirulina sp. (SP) and Chlorella vulgaris (CV). Activated carbons were produced in a two-step process comprising carbonization at 700 °C in an inert atmosphere, followed by physical activation using CO2 at 800 °C. The most promising activated carbons were tested in symmetric coin cell supercapacitors. The biomass’s mineral composition had a large impact on creating porous activated carbon structures. The activated carbon yields decreased for the samples with large mineral fractions due to a relative increase in carbon burnoff. In terms of creating nitrogen-rich activated carbons, CF proved best with a nitrogen content of 8.2%. In terms of porosity, MNS outperformed the other investigated biomass streams with a BET specific surface area of 693.7 m2/g. A correlation between the activated carbon’s microporosity and their specific capacitance was established. The MNS-derived activated carbon performed as the best of the screened streams. Future research should focus on optimizing the activated carbon production process (physical activation and demineralization) to produce highly porous, nitrogen-rich activated carbon.The authors would like to acknowledge the technicians thathave performed the analyses in this study: Elsy Thijssen andGreet Cuyvers for their assistance with the ICP-OES analyses.This work was financially supported by Research FoundationFlanders (FWO SB − 1S92022N
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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