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Kinetic and thermodynamic analysis of the thermal and thermocatalytic conversion of palm oil in the presence of carbonates and metal oxides
Get PDFConsidering the application of low-cost and easily obtained catalysts in the
catalytic pyrolysis of triglyceride biomass to produce renewable hydrocarbons,
this work aimed to evaluate, through thermogravimetric studies, the kinetic and
thermodynamic parameters involved in the thermal and thermocatalytic
conversion of palm oil using carbonate salts (Na2CO3, CaCO3 and K2CO3) and
metal oxides (NiO, Al2O3 and Nb2O5). In the carbonate-catalyzed processes, the
occurrence of two mass loss events during palm oil degradation was observed,
suggesting that the salts act through sequential reactions, which can be attributed
to alkaline hydrolysis and thermal cracking mechanisms. In contrast, in the
processes catalyzed by the metal oxides, palm oil cracking occurred in a single
thermal degradation event, indicating that the reactions promoted by the oxides
take place simultaneously in a single reaction step. The most efficient catalysts
were Na2CO3, K2CO3 and Nb2O5, which reduced the initial palm oil degradation
temperature from 325 °C to 250 °C. The kinetic studies showed that the activation
energy (Ea) of the non-catalytic process was concentrated in the range of 129 to
154 kJ mol–1 for the conversion range of 10% to 90%. When Na2CO3 was added
to the pyrolysis process, a reduction in Ea values was observed up to 55%
conversion, but after that point, Ea values increased, reaching values higher than
175 kJ mol–1. The K2CO3 and Nb2O5, when compared to the process without
catalyst, reduced the Ea values throughout the conversion range studied,
demonstrating a higher catalytic activity. Moreover, the thermodynamic studies
indicated that the reactions promoted by K2CO3 and Nb2O5 occurred in a more
controlled manner compared to the non-catalytic process, leading to the
formation of structures with a higher degree of ordering and providing a lower
energy expenditure in the palm oil cracking and deoxygenation reactions. Thus,
the results showed that potassium carbonate and niobium oxide present potential
to be used in the conversion of triglyceride biomass into biofuels and/or
industrially applicable products.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESConsiderando a aplicação de catalisadores de baixo custo e de fácil obtenção na
pirólise catalítica de biomassas triglicéricas visando a produção de
hidrocarbonetos renováveis, este trabalho teve como objetivo avaliar por meio
de estudos termogravimétricos, os parâmetros cinéticos e termodinâmicos
envolvidos na conversão térmica e termocatalítica do óleo de palma utilizando
sais de carbonatos (Na2CO3, CaCO3 e K2CO3) e óxidos metálicos (NiO, Al2O3 e
Nb2O5). Nos processos catalisados pelos carbonatos, foi observado a ocorrência
de dois eventos de perda de massa durante a degradação do óleo de palma,
sugerindo que os sais atuam por meio de reações sequenciais, que podem ser
atribuídas a mecanismos de hidrólise alcalina e de craqueamento térmico. Em
contraste, nos processos catalisados pelos óxidos metálicos, o craqueamento do
óleo de palma ocorreu em um único evento de degradação térmica, indicando
que as reações promovidas pelos óxidos acontecem simultaneamente em uma
única etapa reacional. Os catalisadores mais eficientes foram o Na2CO3, o K2CO3
e o Nb2O5, que reduziram a temperatura inicial de degradação do óleo de palma
de 325 °C para 250 °C. Os estudos cinéticos demonstraram que a energia de
ativação (Ea) do processo não-catalítico se concentrou na faixa de 129 a 154 kJ
mol–1 para a faixa de conversão de 10% a 90%. Quando o Na2CO3 foi adicionado
ao processo de pirólise, observou-se uma redução nos valores de Ea até a
conversão de 55%, porém, após esse ponto, os valores de Ea aumentaram,
atingindo valores superiores a 175 kJ mol–1. O K2CO3 e o Nb2O5, quando
comparados ao processo sem catalisador, reduziram os valores de Ea em toda
a faixa de conversão estudada, demonstrando uma maior atividade catalítica.
Além disso, os estudos termodinâmicos indicaram que as reações promovidas
por K2CO3 e Nb2O5 ocorreram de forma mais controlada em comparação ao
processo não-catalítico, levando à formação de estruturas com maior grau de
ordenamento e proporcionando um menor gasto energético nas reações de
craqueamento e desoxigenação do óleo de palma. Dessa forma, os resultados
demonstraram que o carbonato de potássio e o óxido de nióbio apresentam
potencial para serem utilizados na conversão de biomassas triglicéricas em
biocombustíveis e/ou produtos de aplicação industrial.São Cristóvã
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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