1,720,999 research outputs found
Diesel soot combustion: KNO3 and KOH catalysts supported on zirconia
No full textKNO3/ZrO2 and KOH/ZrO2 catalysts were studied and found active in the catalytic soot combustion. Two equipments were used to carry out the combustion experiments: a thermogravimetric reactor with an O2/He feed and a fixed bed microreactor with NO/O2/He feed.Fil: Carrascull, Alfredo Lazaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Lick, Ileana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Ponzi, Marta Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Ponzi, Marta Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentin
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
Hydration of α-Pinene over Heteropoly Acid H3PW12O40 and H3PMo12O40
Get PDFHeteropoliacid acid was used as catalyst for the hydration of α-pinene using water as hydroxyl donor. Since the selectivity of desired products is influenced by the reaction conditions, in this paper we study the behavior of phosphotungstic acid (HPW) and phopholmolibdic acid (HPMo) catalysts in homogeneous system under different experimental conditions (inert or oxidizing atmosphere, different ratio water/α-pinene, partial neutralization of the HPW and HPMo to optimize the production of terpene alcohols. When operating in inert atmosphere without agitation, the HPMo is more active than the HPW and by increasing time increases the concentration of α-terpineol. When the catalyst used is HPW products are mainly low molecular weight, while if HPMo is used, preferably the products have high molecular weight. A decrease in the amount of water increases the conversion of α-pinene. When the reaction occurs in equimolar ratio water/α-pinene, using HPMo catalyst, 100% conversion is achieved in 24 hr. The partial neutralization of the acid sites with aluminum, reduces the conversion of α-pinene due to a decrease in Brönsted acidity and production of α-terpineol increases possibly caused by the Lewis acidity is increased.Fil: Avila, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Ponzi, Marta Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Comelli, Nora Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentin
α-Pinene isomerization to camphene: Effect of thermal treatment on sulfated zirconia
No full textThe isomerization reaction of α-pinene produces bicyclic and monocyclic compounds and other products. The purpose of this study is to investigate the influence of the pre-treatment temperature of the catalyst on the concentration of Lewis and Brönsted acid sites and the activity and selectivity of the catalyst. Catalyzed reactions in heterogeneous and homogeneous phases were performed. In heterogeneous reaction, sulfated zirconia (SZ) and pre-treated SZ catalyst at several temperatures were used. The thermal treatment affects the ratio between Brönsted and Lewis sites. Results were contrasted with those obtained with SZ catalyst without thermal treatment. In homogeneous reaction the catalyst is sulfuric acid, and in the reaction medium Brönsted sites are only present coming from the H+ of the acid. The ratio between bi/monocyclic compounds for H2SO4, SZ catalyst and pre-treated catalyst at several temperatures, SZ250, SZ350 and SZ500, varies between 0.4 and 4.3. It can be observed that there exists an optimal thermal treatment where the ratio is higher. FT-IR spectra of adsorbed pyridine on catalysts pre-treated thermally show the presence of Lewis and Brönsted acid sites. The amount of acid sites was determined by TPD of adsorbed pyridine.Fil: Comelli, Nora Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones En Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones En Tecnología Química; ArgentinaFil: Ponzi, Esther Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo En Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Ponzi, Marta Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones En Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones En Tecnología Química; Argentin
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
Dimerization of α-pinene, using Phosphotungstic acid supported on SiO2 as catalyst
Get PDFThe α-pinene dimerization in liquid phase was studied by using phosphotungstic acid catalysts H3PW12O40, (HPW) supported on commercial silica. These catalysts were characterized by XRD, FT-IR and FT-IR of pyridine adsorbed. Catalyst characterization by XRD showed the presence of HPW crystals on HPWSi catalyst. FT-IR spectra showed only bands assigned to the pyridine adsorption on Bronsted acid sites. The catalytic activity was found to depend on the reaction temperature and the amount of catalyst loaded in the reactor, and the highest selectivity in dimers corresponded to the HPW supported. Under reaction conditions 130ºC and 4% catalyst, the most active catalyst showed 100% α -pinene conversion and 55% selectivity to dimers. The selectivity to dimers increases with the increase of the reaction temperature and the amount of catalyst loaded in the reactor.Fil: Merino, Nora Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones En Tecnología Química; ArgentinaFil: Avila, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Comelli, Nora Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones En Tecnología Química; ArgentinaFil: Ponzi, Esther Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Ponzi, Marta Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones En Tecnología Química; Argentin
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
Catalysts of alkaline nitrates supported on oxides for the diesel soot combustion: Deactivation by hydro-treatment and CO2
Get PDFThe deactivation of supported catalysts CsNO3 and LiNO3 for diesel soot combustion is studied in this work. The effect of hydro-treatment at high temperature and presence of CO2 in feed flow were investigated. Catalysts were characterized by means of X ray diffraction, DSC technique and FTIR. A fixed bed reactor was used to measure activity of fresh and deactivated catalysts with NO2/O2 feed. Thermogravimetrical system with air/CO2 feed was used to study the deactivation with CO2. Catalysts with LiNO3 were the most resistant to deactivation by hydro-treatment, and they are not deactivated by CO2. It is postulated that the cesium nitrate solubilizes in water and is eliminated during the hydro-treatment, instead, lithium species interacted more strongly with the support and generate more resistance species.Fil: Ruiz, Maria Lucia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Lick, Ileana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Ponzi, Marta Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Ponzi, Esther Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentin
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