1,720,967 research outputs found
The Effect of Base Catalyst in the Citronellal Purification of Kaffir Lime Oil Precipitated by NaHSO3 and Na2SO3
No full textCitronellal is the main component in kaffir lime oil that has great potential utilization in industrial and pharmaceutical field. Citronellal purification using conventional method, such as destillation, requires lots of solven, special equipment and lots of time. Alternatively, purification method using base catalyst NaHSO<sub>3</sub> and Na<sub>2</sub>SO<sub>3</sub> as reagent could be more simple. This research aimed to evaluate the effect of the base catalyst used for hydrolysis in the purification process of citronella using salt reaction with NaHSO<sub>3</sub> and Na<sub>2</sub>SO<sub>3</sub> reagents. The experiments was conducted in the Laboratory of Organic Chemistry, Brawijaya University, Malang, from August 2015 to February 2016. The research was arranged a randomized block design with factorial treatments. The first treatments was two types of reagents, NaHSO<sub>3</sub> and Na<sub>2</sub>SO<sub>3</sub>. The second one was the variations of base catalyst used for hydrolyzing NaHCO<sub>3</sub>, Na<sub>2</sub>CO<sub>3</sub> and NaOH. The purity of hydrolyzed citronellal was measured by gas chromatography-mass spectrometry. The highest purity of citronella 89,29 % was obtained with the used of Na<sub>2</sub>SO<sub>3 </sub>reagent at the mole ratio 1:2, hydrolyzed by Na<sub>2</sub>CO<sub>3</sub> (pH 10.98). Thus the method, can be recommended in purifying citronellal from kaffir lime oil.</jats:p
Effect of Hydration and Oxidation Reactions of The Chemical Composition of Kaffir lime (Cytrus hystrix DC.) Oil
No full textThis research aims to determine changes of the chemical composition in the hydration and oxidation reaction of Kaffir lime (Cytrus hystrix DC.) oil. The hydration reaction was carried out using a Amberlyst catalyst with variation time for 1.5, 3, and 4.5 hours. Furthermore, the oxidation process was carried out using PCC catalyst with variation time for 1, 1.5, and 3 hours. Then, the analysis of chemical composition was performed using GC-MS. The results showed that hydration reaction process for 1,5 hours has changed monoterpenes micrene and b-ocimen turned into linalool and it changes citronellal to be linalool, citronellol and dimer ether citronellyl citronellol. The longer process of hydration tends to increase the dimer ether citronellyl citronellol products. Within that process, it has turned citronellal into isopulegol and isopulegone. The longer oxidation will decrease isopulegone products
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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