251 research outputs found
Pd–Cu interaction in Pd/Cu-MCM-41 catalysts: Effect of silica source and metal content
No full textPd/Cu-MCM-41 catalysts for the hydrodechlorination of CF3OCFClCF2Cl to CF3OCFCF2 were prepared. Palladium- and copper-containing samples (Pd/Cu = 1 molar ratio) were synthesized by adding Pd2+ and Cu2+ during the formation of MCM-41, and then the slurries were aged by microwave-hydrothermal treatment. The effect of the silica source (silicates or TEOS) and total metal loading (2.4 and 4.0 wt.%) on the chemical–physical properties and catalytic performances was studied. Bimetallic silicate-derived samples show features similar to those of the pristine MCM-41, regardless of the total metal content. Conversely, the long-range order of the mesoporous structure decreases for TEOS-derived catalysts, and large metal contents seem to alter the structure for these materials. During template removal by thermal treatment, palladium and copper are on the surface of MCM-41 particles, forming Pd1−xCuxO solid solutions whose composition is silica source-dependent. The amount of copper in Pd1−xCuxO is greater for TEOS-derived samples. After reduction, both Pd- and Cu-enriched alloys were found by XRD in silicate-derived samples, while XPS measurements indicated that the surface of the catalyst is enriched with copper. XRD and XPS analyses on TEOS samples indicated that the surface Cu/Pd ratio is closer to 1, and fcc PdCu alloys with a high copper content were identified. The composition of metallic particles modifies the selectivity, TEOS-derived catalysts being more selective to the target CF3OCFCF2.Fil: Benito, Patricia Virginia. Università di Bologna; ItaliaFil: Gregori, Manuel. Università di Bologna; Italia. R&D Centre. Solvay Specialty Polymers SpA; ItaliaFil: Andreoli, Sara. Università di Bologna; ItaliaFil: Fornasari, Giuseppe. Università di Bologna; ItaliaFil: Ospitali, Francesca. Università di Bologna; ItaliaFil: Millefanti, Stefano. R&D Centre. Solvay Specialty Polymers SpA; ItaliaFil: Avila, Maria Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Garetto, Teresita Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Albonetti, Stefania. Università di Bologna; Itali
O papel de Santa Maria como centro de drenagem da renda fundiaria
No full textDissertação (mestrado) Universidade Federal de Santa Catarina. Centro de Ciencias HumanasEste trabalho constitui-se em uma contribuição ao entendimento do papel que a cidade de santa Maria representa como centro de drenagem da renda fundiária. A cidade de Santa Maria localizada no centro geográfico do estado do RS, em meio as áreas de campo da campanha gaúcha e tendo ao norte limite com as regiões de colonização européia constitui-se em um centro de residência de proprietários rurais absenteístas. Nesta perspectiva este trabalho pretende verificar a importância da propriedade fundiária controlada pela cidade de Santa Maria, definindo seu espaço de atuação e a estrutura da propriedade rural citadina. Da mesma forma, busca analisar os tipos sociais de proprietários fundiários absenteístas que residem na cidade, bem como a dinâmica de atuação destes proprietários no espaço. Para apreender as conseqüências da renda fundiária tanto no campo quanto na cidade, procura-se abordar a localização intra-urbana dos proprietários rurais assim como a dinâmica locacional da residência destes proprietários e a estrutura urbana da cidade. A análise da atuação destes proprietários rurais citadinos tanto na vida urbana quanto na vida regional busca demonstrar a importância a que estes assumem no conjunto das relações cidade-região
Theoretical and experimental analysis of the oxidation of CO on Pt catalysts supported on modified TiO2(101)
No full textAbstract The dynamics of the CO adsorption on Pt nanoparticles deposited on TiO2(101) (pure, N-doped and/or reduced) have been investigated using UV-visible diffuse reflectance spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy and density functional theory. The results point to that N-doping and oxygen vacancies in the Pt/N-TiO2 system should favor catalytic reactions in which CO conversion into CO2 takes place mediated by support surface O atoms.Fil: Morgade, Cecilia Ines Nora. Universidad Tecnológica Nacional. Facultad Regional Bahía Blanca; ArgentinaFil: Vignatti, Charito Ivana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Avila, Maria Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Cabeza, Gabriela Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin
Study of the water-gas shift reaction over Pt supported on CeO 2-ZrO2 mixed oxides
No full textThe water gas shift (WGS) reaction was studied on Pt/CeO2, Pt/ZrO2 and Pt/CexZr1-xO2 catalysts. All the samples were characterized by a variety of physical and spectroscopic techniques. The catalyst activities were evaluated at 250 °C in a recirculating reactor through CO conversion versus time tests and also by in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS). The sample activity for the WGS reaction depended on chemical composition. Pt/CexZr1-xO2 catalysts with x ≥ 0.5 were more active than Pt/CeO2, probably because the addition of Zr to ceria increased both the surface area and the reducibility of ceria. The lowest CO conversion rates were obtained on Pt/ZrO2 and Zr-rich Pt/Ce xZr1-xO2 samples. Based on DRIFTS experiments, this result was interpreted by considering that in the WGS formate associative mechanism the stability of formate species is higher on Zr-rich supports.Fil: Vignatti, Charito Ivana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Avila, Maria Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Apesteguia, Carlos Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Garetto, Teresita Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin
One-pot sonocatalyzed synthesis of sol–gel graphite electrodes containing gold nanoparticles for application in amperometric sensing
No full textWe propose here a one-pot synthetic approach to prepare sol–gel graphite electrodes containing gold nanoparticles (AuNPs). At variance with the traditional synthesis, in which AuNPs are prepared in advance with respect to the silica matrix, they were here obtained directly inside the sol–gel, during its formation. Two reduction methods, namely chemical and thermal reduction, were used to achieve AuNPs starting from a suitable gold precursor, either consisting of NaAuCl 4 or HAuCl 4 . Different experimental parameters were tested in order to direct the synthesis of the material to the characteristics sought, namely Si/Au molar ratio, graphite (g): silane precursor (mL) ratio, chemical nature of the gold precursor and of the reductant, duration and temperature of thermal treatment. Sol–gel was prepared by means of sonocatalysis, in order to reduce the amount of solvent and time necessary for the hydrolysis step. Composition of the material, as well as shape, size and distribution of AuNPs inside the silica matrix was evaluated by spectroscopic and microscopic techniques. Furthermore, electrochemical tests allowed us to ascertain the good conductivity of the composite material and the electrocatalytic activity of AuNPs with respect to glucose and ascorbic acid oxidation. These tests demonstrated that the electrodes obtained by thermal reduction show the best performance in terms of sensitivity for the detection of these analytes, suggesting the possible application of this composite in the field of amperometric sensin
Imagens de Otto Maria Carpeaux: esboço de biografia
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas, Programa de Pós-Graduação em História, Florianópolis, 2015.Este esboço de biografia procura citar algumas imagens de Otto Maria Carpeaux: construções biográficas de naturezas múltiplas, elaboradas em contextos, por atores e sob condições igualmente díspares. Está constituído a partir de uma visão crítica da História, o que permite que ?outras imagens?, fragmentárias e não monumentais, também tenham espaço. Em diálogo com o princípio da montagem, este esboço apresenta-se em duas partes. Na primeira, Imagens possíveis, estão citadas as imagens elaboradas em vida e post mortem acerca do austríaco-brasileiro que nasceu em Viena em 1900, se exilou no Brasil em 1939 e morreu no Rio de Janeiro, em 1978. Na segunda, Montagens possíveis, apresentam-se duas possibilidades de exercício biográfico: pela leitura alegórica do documentário O velho e o Novo (Otto Maria Carpeaux), entendido como instrumento de intervenção no contexto ditatorial brasileiro e de uma reelaboração biográfica concernentes às suas experiências europeias; e pelo Caderno de imagens críticas, registro dos encontros em Carpeaux pelo meio de imagens críticas produzidas a partir da cesura do presente.Abstract : This biographical sketch attempts to quote some images of Otto Maria Carpeaux: various types of biographical constructions, carried out in different contexts by disparate authors under conditions just as distinct. It stems from a critical view of history, allowing for ?other images? fragmented and non-monumental ? to share the space.In dialogue with the montage principle, this sketch has two parts. The first, Possible Images, quotes the images produced during and after the life of the Austrian-Brazilian, who was born in Vienna in 1900, went to Brazil in exile in 1939 and died in Rio de Janeiro in 1978. The second part, Possible Montages, presents two possibilities of a biographical exercise: through the allegorical reading of documentary O Velho e o Novo (Otto Maria Carpeaux), understood as an instrument of intervention in the Brazilian dictatorship context and as a biographical retelling of the author?s European experiences; and through my Scrapbook of Critical Images, a record of the encounters in Carpeaux through critical images produced from the caesura of the present
Tropical sol da liberdade, de Ana Maria Machado: uma narrativa do tempo de exceção
No full textThe 21 years of a state of exception experienced by Brazil broke out on March 31, 1964, when the military deposed then President João Goulart, accused of defending communist ideals. In Tropical sol da liberdade, Ana Maria Machado weaves, from different perspectives (the memory of the protagonist Lena, the testimony of her mother, letters and reports) images of the horrors that marked the state of exception imposed by the coup. In this article, we analyze the literary construction of the work and the way in which the author, situated in the characteristics of contemporary literature, reflects on the fabric of the literary text while making literature a space of memory.Os 21 anos de estado de exceção vividos pelo Brasil eclodiram no dia 31 de março de 1964, quando os militares depuseram o então presidente João Goulart, acusado de defender ideais comunistas. Ana Maria Machado, em Tropical sol da liberdade, tece, a partir de diferentes perspectivas (a memória da protagonista Lena, o testemunho da mãe, cartas e reportagens) imagens dos horrores que marcaram o estado de exceção imposto pelo golpe. Neste artigo, analisamos a construção literária da obra e a maneira com que a autora, situada nas características da literatura contemporânea, reflete sobre a tessitura do texto literário ao mesmo tempo em que torna a literatura um espaço da memória
Deep oxidation of benzene on Pt/V2O5-TiO2 catalysts
No full textThe combustion of benzene was studied on Pt supported on V 2O5-TiO2 samples containing different amounts of V2O5. Vanadium was highly dispersed as V4+ for low V2O5 loadings, forming a vanadia monolayer on titanium dioxide for a V2O5 concentration of about 5%wt. V2O5-TiO2 samples were more active than V 2O5 and TiO2 single oxides, and the activity increased with the vanadia content. The platinum dispersion in Pt/V 2O5-TiO2 catalysts increased with the V 2O5 loading but the activity for the deep oxidation of benzene exhibited an opposite trend. Benzene combustion was a structure sensitivity reaction promoted on larger metallic Pt crystallites which were preferentially formed when the V2O5 content in the sample was decreased.Fil: Garetto, Teresita Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química; ArgentinaFil: Avila, Maria Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Vignatti, Charito Ivana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Venkat Rao, V.. Indian Institute of Chemical Technology; IndiaFil: Chary, Komandur. Indian Institute of Chemical Technology; IndiaFil: Apesteguia, Carlos Rodolfo. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin
Effect of support on the deep oxidation of propane and propylene on Pt-based catalysts
No full textThe complete oxidations of propane and propylene were studied on Pt supported on CeO2, TiO2 and Al2O3. The catalyst activities were evaluated through conversion versus temperature (light-off curves) and conversion versus time tests. Propane oxidation turnover rates (TOF) followed the order: Pt/TiO2 > Pt/CeO2 > Pt/Al2O3. The higher activity on Pt/CeO2 than on Pt/Al2O3 was interpreted by considering that the combustion of C3H8 on Pt/CeO2 occurs not only on Pt0 sites but also on perimeter Pt0–Ce3+ sites providing an additional oxidation pathway. Propane uptake on Pt/TiO2 was 5.5 times higher than on Pt/CeO2. This drastic increase of the density of adsorbed C3H8 molecules around the metallic Pt active sites would explain the high TOF values observed on Pt/TiO2 because the reaction is positive order with respect to propane. The propylene oxidation turnover rate trend was Pt/CeO2 > Pt/Al2O3 ≅ Pt/TiO2. Kinetic studies showed that on the three catalysts the apparent activation energy of propylene oxidation was about the same while the reaction orders were positive in oxygen and negative or zero in propylene. The higher activity of Pt/CeO2 catalyst was explained by considering that the Pt-catalyzed reduction of ceria forms oxygen vacancies that would improve the mobility of lattice oxygen of the support and its transfer to the propylene species adsorbed on the metal.Fil: Avila, Maria Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Vignatti, Charito Ivana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Apesteguia, Carlos Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Garetto, Teresita Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin
Las Cantigas de Santa Maria: “Como Santa Maria ajudou a Emperadriz de Roma”/ “Cómo Santa María ayudó a la emperatriz de Roma”
No full text10 pages, English and Spanish translation availableAlfonso X was king of “Castilla, León, Sevilla, Córdoba, Murcia, Jaén, and el Algarbe.” As evidenced by his title, he came to have possession of various kingdoms in Iberia. He was born in Toledo in 1221 and died in Seville in 1284, at 63 years of age. He is called the Learned King because he was an author, poet, musician, and historian, and because he supported artists and translators. Furthermore, he employed Christians, Jews, and Muslims in his translation workshop in Toledo.
His Cantigas de Santa Maria is a repertoire of songs compiled in four manuscripts between 1257 and 1283. The Cantigas consist of 420 narrative songs that focus on the Virgen Mary and the miracles that she performs across Christendom. Originally, the text was written in Galician-Portuguese, from the northeast region of Iberia. Galicia is the site of Santiago de Compostela, the final destination of the pilgrimage route known as the Camino de Santiago (Saint James’s Way). Each story is comprised of text, images, and music. The combination of texts and images portrays day-to-day life and, often, the less-documented common peoples of the Middle Ages in Europe.
This unit, edited by Diane Burke Moneypenny and Allison Carberry Gottlieb, contains the original text in Galician-Portuguese of Cantiga 5, “How the Virgin Mary helped the Empress of Rome.” The Spanish version (for use in contexts where the language of instruction is Spanish) has an introduction, notes, and translation into modern Spanish (by Sol Miguel-Prendes). The English version has an English introduction and notes, and an English translation of the Cantiga
- …
