1,720,954 research outputs found
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
Intensificación en la epoxidación de aceites usados de cocina utilizando catalizadores ácidos
No full textilustraciones, diagramas, fotografíasEste trabajo se centra en la intensificación del proceso de epoxidación de aceites usados
de cocina (UCO) mediante catálisis de transferencia de fase y el uso de reactores de
milifluidos de flujo segmentado. Se desarrolló un nuevo catalizador heteropoliácido
(HPA) modificado mediante la hibridación del ácido fosfotúngstico con surfactantes, lo
que le permitió actuar como catalizador de transferencia de fase y transportador de
oxígeno, eliminando la necesidad de ácido peracético. Aunque la actividad catalítica
mejoró, la selectividad hacia los grupos oxirano fue limitada, lo que requirió el uso de
una resina de intercambio iónico ácida como co-catalizador para optimizar el
rendimiento. Posteriormente, se empleó un reactor de flujo segmentado para intensificar
el proceso, optimizando parámetros clave con aceite de soya como modelo y extendiendo
luego el estudio a UCO. Se alcanzó hasta un 82 % de conversión, 86 % de selectividad y
una productividad de 7,91 mL·min⁻¹, con un contenido de oxígeno oxirano del 4,02 % en
peso. Los resultados demuestran el potencial de los reactores de flujo segmentado para
una epoxidación eficiente y escalable, contribuyendo a la producción sostenible de
oleoquímicos de segunda generación a partir de aceites residuales (Texto tomado de la fuente).This work focuses on the intensification of the epoxidation process of used cooking oils
(UCO) through phase-transfer catalysis and continuous slug-flow millireactors. A novel
modified heteropolyacid (HPA) catalyst was developed by hybridizing phosphotungstic
acid with surfactants, acting as both phase-transfer catalyst and oxygen carrier,
eliminating the need for peracetic acid. While catalytic activity was enhanced, selectivity
towards oxirane groups was limited, requiring an acid ion exchange resin as a co-catalyst
to improve performance. A slug-flow millireactor was then employed for process
intensification, optimizing key parameters using soybean oil as a model and later
extending the study to UCO. The process achieved up to 82% conversion, 86%
selectivity, and 7.91 mL·min⁻¹ productivity, with a 4.02% wt. oxirane oxygen content.
Results demonstrate the potential of continuous slug-flow reactors for efficient and
scalable epoxidation, contributing to the sustainable production of second-generation
oleochemicals from waste oils.Ce travail porte sur l’intensification du processus d’époxydation des huiles de cuisson
usagées (UCO) par catalyse de transfert de phase et l’utilisation de réacteurs
millifuidiques à flux segmenté. Un nouveau catalyseur d’acide hétéropolyacide (HPA)
modifié a été développé en hybridant l’acide phosphotungstique avec des tensioactifs,
agissant à la fois comme catalyseur de transfert de phase et transporteur d’oxygène,
éliminant ainsi le besoin d’acide peracétique. Bien que l’activité catalytique ait été
améliorée, la sélectivité vis-à-vis des groupes oxirane était limitée, nécessitant l’ajout
d’une résine échangeuse d’ions acides comme co-catalyseur pour optimiser les
performances. Un réacteur à flux segmenté a ensuite été utilisé pour intensifier le
processus, en optimisant les paramètres clés avec l’huile de soja comme substrat modèle,
puis en étendant l’étude aux UCO. Le procédé a permis d’atteindre jusqu’à 82 % de
conversion, 86 % de sélectivité et une productivité de 7.91 mL·min⁻¹, avec une teneur en
oxygène oxiranique de 4.02 % en poids. Ces résultats démontrent le potentiel des
réacteurs à flux segmenté pour une époxydation efficace et évolutive, contribuant à la
production durable d’oléochimiques de seconde génération à partir d’huiles usagées.Programa ECOSNORD, Minciencias Contract 487-2021Minciencias Contract 933-2023DAAD research scholarship 2023/2024Max Planck Institute of Colloids and InterfacesDoctoradoDoctor en Ingeniería QuímicaBiorefineries – Biofuel
Deacidification of used vegetable oils by extraction method with solvents
No full textilustraciones, fotografías, gráficas, tablasLa presente investigación evalúa la factibilidad técnica de la extracción con solventes de los ácidos grasos libres presentes en los aceites vegetales usados. La primera parte de la investigación fue realizada por medio de un proceso de extracción en sistemas de tanque agitado operados por lotes, en el cual se seleccionó etanol como el mejor solvente para el proceso y las mejores condiciones de temperatura (60 ºC), relación másica aceite:solvente (1:2) y contenido de agua (4%) en el solvente. A estas condiciones la remoción fue del 77% de acidez, 37% de color, 53% de polares, y las pérdidas de aceite en el solvente fueron menores al 0.8%. Por otra parte, se encontró que propiedades como el índice de peróxido, índice de yodo, índice de saponificación, índice anisidina y la distribución de ácidos grasos no son afectadas por el proceso de extracción. Posteriormente, la extracción fue realizada en un contactor de película líquida descendente, el cual permitió la operación en continuo y los mejores resultados fueron obtenidos con una relación másica de aceite:etanol de 1:2, flujo de aceite 0.74 kg/h y una longitud de empaque de 1.07 m. Se alcanzó una efectividad de remoción de impurezas de 51% de acidez, 17% de color, 6.7% de polares. (Texto tomado de la fuente).This research evaluates the technical feasibility of solvent extraction of free fatty acids present in used vegetable oils. The first part of the research was carried out through a batch extraction process, in which ethanol is selected as the best solvent for the process and the best conditions: temperature (60 ºC), oil:solvent mass ratio (1: 2 ) and water content (4%) in the solvent. These allowed to achieve a removal of 77% acidity, 37% color, 53% polar and oil losses in the solvent less than 0.8%. On the other hand, it was found that properties such as peroxide value, iodine value, saponification value, anisidine value and fatty acid distribution were not affected by the extraction process. Subsequently, the extraction was carried out in a liquid film contactor, which allowed continuous operation and the best results were obtained with an oil:ethanol mass ratio of 1:2, an oil flow of 0.74 kg/h and a length of packaging of 1.07 m, achieved an impurity removal effectiveness of 51% acidity, 17% color, 6.7% polar.MaestríaMagíster en Ingeniería - Ingeniería QuímicaBiorrefinerías – Biocombustible
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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