1,720,970 research outputs found
Production of glycerol carbonate from industrial grade crude glycerol via microwave-assisted transesterification / Teng Wai Keng
No full textThis research aims to produce glycerol carbonate (GC) from industrial-grade crude glycerol originating from a biodiesel plant via microwave-assisted transesterification (MAT). Aspects including a feasibility study of transforming industrial-grade crude glycerol into GC via MAT, the study of the effect of impurities in the crude glycerol, process optimization, and kinetic study were investigated. Three types of glycerol, the pure form, crude glycerol at 70% and 86%, were transesterified with dimethyl carbonate
(DMC) using CaO as a catalyst. A comparison study was made between conventional transesterification and MAT. The research found that crude glycerol of 70% purity produced higher GC yield in both conventional and MAT processes with the latter showing better energy efficiency. The highest GC yield of 93.4% was obtained from glycerol with a purity of 70% under MAT with 1 wt.% of CaO, 2:1 molar ratio of DMC/glycerol at 65 °C and 5 min reaction time. The yield of GC was observed to increase with temperature, time, and molar ratio but independent from the catalyst loading. The impact of single and multiple impurities in crude glycerol was investigated by adding impurities to pure glycerol. Methanol, sodium methylate, and soap were found to give a positive effect whereas water and fatty acid inhibited GC synthesis. The addition of impurities of 20 wt.% methanol and 1 wt.% sodium methylate increased GC yield by four times, from 7.62% to 30.56%. At its optimized reaction conditions, the GC yield can be further increased to 80.43% through the addition of 5 wt.% sodium methylate and 0.01 wt.% of soap. This shows the impurities which might otherwise be undesirable for the transesterification process under normal circumstances have unusually demonstrated positive effects on the performance of The MAT process was optimized to yield 99.5% GC from 70% purity crude glycerol at 65 °C with 1 wt.% catalyst loading in 5 min at a DMC/glycerol molar ratio of 2.5. As a comparison, MAT of pure glycerol was also carried out and the findings showed that merely 66.6% GC yield can be achieved at its longer reaction time of 60 min and higher catalyst loading of 6 wt.%. The reaction time is the most significant factor for MAT of both types of glycerol. MAT reaction fitted well to an irreversible second-order kinetic model. The values of rate constants between 45 °C to 65 °C were in the range of 2.34 - 2.59 x 10-2 L/mol.min, which is one order of magnitude higher than that of conventional heating. Furthermore, a relatively lower activation energy of 4.53 kJ/mol is needed for GC production via MAT of crude glycerol in comparison to the conventional transesterification process. The research demonstrated the feasibility of direct utilization of industrial-grade crude glycerol from biodiesel plants to produce GC. The microwaveassisted process effectively transformed crude glycerol into value-added GC, in addition to its cost-effectiveness in using biodiesel waste as raw material. Hence, compared to other reported transformation techniques, MAT of crude glycerol was shown to be an economically viable, sustainable, robust, and energy-efficient synthesis process of GC
Theme One : Cultural Traditions, Physical and Mental Health, and Sustainability (III)
No full textModerator : TENG Wai (South China Normal University)
Speakers :
1. The Right to Science: Decolonizing Knowledge to Preserve Epistemic Biodiversity
Speaker : Nicoletta DENTICO (Global Health Justice Program, Society for International Development, Italy)
2. The Contribution of Traditional African Medicine in the Fight Against COVID-19 and Other Tropical Diseases
Speaker : Jérôme MUNYANGI WA NKOLA (University of Kolwezi, Congo)
3. Ayurveda in Healthcare: Swastha Vritta (The Preventive and Social Medicine)
Speaker : Thushara LAL S (Tamil Nadu Dr. M.G.R. Medical University, India)
4. Revisiting the Role of Western Foundations in the Medical System of the Global South
Speaker : SIT Tsui (Southwest University
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No full text“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
No full textWe 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
No full textWe 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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