378 research outputs found
Exploring the regioselectivity for the cycloaddition of azides to alkynes catalyzed by dinuclear copper clusters (Cu2AAC) with the topology of 2rho(r) and 2rho(r)
No full textThis study constitutes an extension of a previous research on the regioselectivity of the copper catalyzed cycloaddition of azides to alkynes (1) (the CuAAC reaction) by Quantum Chemical Topological methods. In particular, by following the evolution the topology of the laplacian of the electronic charge density and its gradient vector field along the reaction coordinates, computed with different Density Functionals (B3LYP, LCwPBE, M06-L, wB97XD, and M06-2X) and 6-311++G(d,p) basis set. For the mononuclear process, we found that a H-type interaction conditions the attack of the azide in the 1,5-CuAAC.
In addition, given that experimental evidences (2) seem to suggest the participation of a second Cu atom in the reaction coordinate, we have explored very recently (3) the mechanism involving a dinuclear copper cluster at the LCwPBE/6-311++G(d,p) level. Interestingly, the catalyst modifies the uncatalyzed Huisgen mechanism, by inducing sequentially first the terminal N-C bond and the internal afterwards in a concerted fashion for the 1,4-CuAAC and stepwise for the 1,4-Cu2AAC. Furthermore, as seen in the topology of the laplacian, the catalyst provoked that a carbon acts as a nucleophile and turned pericyclic mechanism into pseudopericyclic (3).
[1] Calvo-Losada S., Pino M.S. and Quirante J.J., J. Mol.Model., 20, 2187 (2014)
[2] Worrell B. T., Malik J. A. and Fokin V. V., Science, 340, 457 (2013)
[3] Calvo-Losada S., Pino M.S. and Quirante J.J., J. Phys.Chem. B, 119,1243 (2015)Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Do pensamento á ficção no exílio de Francisco Ayala
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em Literatura.Do pensamento à ficção quer expressar um trânsito na obra de Francisco Ayala, que começa com o exílio na América em 1939 e se estende ao exercício intelectual do escritor espanhol nesse período. Representante de um pensamento liberal que se fundamenta no conhecimento racional e historicista, desenvolvido no campo da sociologia e da política, ele atua no meio argentino e latino-americano em geral através de artigos publicados em revistas e jornais, livros teóricos e traduções. Seu trabalho busca refletir sobre os acontecimentos históricos da primeira metade do século XX e do pós-guerra no contexto mundial de crise da modernidade, com o objetivo de compreender as mudanças sociais e situar o papel da elite letrada frente às urgências da sociedade de massas, observando como o estado das letras se viu sitiado pelo avanço das imagens dos meios de comunicação. O exílio coloca Ayala frente a uma realidade emergente e descentrada nos países por onde andou. Isso alimenta um desvio gradual da atividade sociológica para uma dedicação literária predominante. Ao final do exílio, na década de 70, e das viagens que esse período proporcionou, ele acaba por incorporar as imagens às letras e, mesmo mantendo a consciência do seu eu, experimenta as possibilidades de ser outros através da narrativa ficcional. Esse processo caracteriza um avanço sobre os limites do pensamento modernista, envolvendo Francisco Ayala numa situação tardo-moderna por experimentar, nas décadas de 50 e 60, elementos hoje atribuídos ao pós-modernismo. From thought to fiction it wishes to express a transit in the work of Francisco Ayala, which starts with the exile in America in 1939 and continues towards the intellectual exercise of the Spanish author in this period. Representative of a liberal thought which bases itself in the rational and historicist knowledge, developed in the field of Sociology and of the politics, he acts in the Argentinian and Latin-american as a general rule environment through articles published in magazines and newspapers, theoretical books and translations. His works aims to reflect upon the historical events of the first half of the XXth century and of the pos-war period in the world context of the crisis of modernity, with the objective of understanding the social changes and to situate the role of the educated elite as far as the urgencies of the mass society are concerned, noticing how the state of the education has found itself besieged due to the advances of the images of the communication media. The exile puts Ayala facing an emergent reality and decentred from the countries where he had traveled to. This provokes a gradual deviation from the sociological activity to a predominant literary dedication. At the end of the exile, during the 70#s, and of the trips, which this period had offered him, he finally incorporates the images into the texts and, even keeping the awareness of his self, the author experiences the possibilities of being others through the fictional narrative. This process characterizes an advance over the limits of the modernist thought, engaging Francisco Ayala into a late-modern situation for experimenting, during the 50#s and the 60#s, elements credited to the post-modernism
Water distribution in laterals and units of subsurface drip irrigation. II: Field evaluation.
No full textThe performance of drip irrigation and subsurface drip irrigation (SDI) laterals has been compared. Two emitter models (one compensating and the other noncompensating) were assessed. Field tests were carried out with a pair of laterals working at the same inlet pressure. A procedure was developed that recorded head pressures at both lateral extremes and inlet flow during irrigation. Both models showed similar behavior and soil properties affected their discharge. On the other hand, the performance of a field SDI unit of compensating emitters was characterized by measuring pressures at different points and inlet flow. Finally, the distribution of water and soil pressure in the laterals and the unit were predicted and irrigation uniformity and soil pressure variability were also determined. Predictions agreed reasonably well with the experimental observations. Thus, the methodology proposed could be used to support the decision making for the design and management of SDI system
DFT study of competitive Wolff rearrangement and [1,2]-hydrogen shift of β-oxy-α-diazo carbonyl compounds
No full textEmitter discharge variability of subsurface drip irrigation in uniform soils: effect on water-application uniformity
No full textEmitter discharge of subsurface drip irrigation (SDI) decreases as a result of the overpressure in the soil water at the discharge orifice. In this paper, the variation in dripper discharge in SDI laterals is studied. First, the emitter coefficient of flow variation CVq was measured in laboratory experiments with drippers of 2 and 4 L/h that were laid both on the soil and beneath it. Additionally, the soil pressure coefficient of variation CVhs was measured in buried emitters. Then, the irrigation uniformity was simulated in SDI and surface irrigation laterals under the same operating conditions and uniform soils; sandy and loamy. CVq was similar for the compensating models of both the surface and subsurface emitters. However, CVq decreased for the 2-L/h non-compensating model in the loamy soil. This shows a possible self-regulation of non-compensating emitter discharge in SDI, due to the interaction between effects of emitter discharge and soil pressure. This resulted in the irrigation uniformity of SDI non-compensating emitters to be greater than surface drip irrigation. The uniformity with pressure-compensating emitters would be similar in both cases, provided the overpressures in SDI are less than or equal to the compensation range lower limit
La conspiración y la Guerra Civil para Payne y Palacios
No full textStanley Payne y Jesús Palacios escriben una presunta biografía de Franco que es una apología de la figura del dictador, en donde se evitan las referencias críticas y datos objetivos hoy demostrados para lograr ensalzar su figura. Para estos autores la conspiración contra la República estaría justificada dada la falta real de democracia en España y el deterioro social; para ellos el régimen republicano estaría prácticamente violando la legalidad, por lo que rebelarse contra él no sería ningún acto ilegítimo. En este marco el asesinato de Calvo Sotelo sería el factor decisivo que alentó a Franco a sublevarse. Ante este panorama la guerra sería el mal inevitable llevada con bastante eficacia por Franco, no cayendo en una excesiva represión ni durante la contienda ni al final. Igualmente reducen las cifras de la represión que causan los sublevados, añadiendo presuntos elementos que la atenuarían, y exaltan la capacidad estratégica de Franco negando que sus decisiones militares ralentizasen el ritmo de la guerra. Por último reproducen los tópicos de Juan Negrín como agente de Moscú, reproduciendo todos los tópicos convenientemente actualizados de la vieja historiografía franquista. Palabras clave: Franco, Apologías, Conspiración, Guerra civil, Tergiversación Abstract: Stanley G. Payne and Jesus Palacios have written a self-proclaimed biography of Franco which is actually an apology in favour of the late dictator. In order to extoll his historical figure critical analyses and objective facts are omitted. For both authors the conspiracy against the Republic was justified because of the lack of democracy in Spain and the high degree of social unrest. For them the Republican regime was in practice violating the legality. On this basis a rebellion against it was not illegitimate. In this context Calvo Sotelo´s murder was the decisive factor which pushed Franco to rebel. The war appears as an unavoidable evil. Franco carried out the fight with reasonable efficiency and did not fall prey to excessive violence either during the war or afterwards. Payne and Palacios drastically reduce the amount of violence lashed out by the rebels and add some alleged factors which militated in the same direction. They extoll Franco´s strategic capability and oppose the view that his military decisions kept the war going for too long. They take refuge in the customary topics about Juan Negron being a Moscow agent and adhere to the conveniently modernized Francoist myths of the old historiography established during the Franco regime. Key words: Franco, Apology, Conspiracy, Civil War, Manipulatio
Cohesin in cancer: chromosome segregation and beyond
No full textCohesin is an evolutionarily conserved, four-subunit complex that entraps DNA fibres within its ring-shaped structure. It was originally identified and named for its role in mediating sister chromatid cohesion, which is essential for chromosome segregation and DNA repair. Increasing evidence indicates that cohesin participates in other processes that involve DNA looping, most importantly, transcriptional regulation. Mutations in genes encoding cohesin subunits and other regulators of the complex have recently been identified in several types of tumours. Whether aneuploidy that results from chromosome missegregation is the major contribution of cohesin mutations to cancer progression is under debate.The author apologizes to colleagues whose relevant work on cohesin is not cited here. She thanks the group of F. X. Real (Spanish National Cancer Research Centre (CNIO), Madrid, Spain), as well as members of her own group, for discussions. The author's research is currently funded by the Spanish Ministry of Economy and Competitiveness (MINECO), grant SAF-2010-21517.S
The blind spots of secularization
No full textAccording to several international surveys Spain is among the western countries with the most negative views of Jews. While quantitative data on the topic accumulates, there is a significant lack of interpretative approaches that might explain the particular Spanish case. This paper presents the background, methodology and major results of a discussion group-based study on antisemitism, which was conducted in Spain in the autumn of 2009. The study identifies and locates in different socio-economic and ideological milieus the range of stereotypical discourses on Jews, Judaism and the Arab–Israeli conflict in Spain. Analysis of the group meetings shows that, despite growing secularization in Spanish society, the central explanatory variable for persisting and resurging antisemitism in this country is still religion in a broad cultural sense.N
El proyecto de conservación de la Puerta del Paraíso. Una nueva frontera en la restauración de los bronces.
No full textArtículo de anuarioEn este artículo, se aborda la larga historia que ha hecho del proyecto de preservación de la Puerta del Paraíso del Baptisterio de Florencia, uno de los más completos proyectos de investigación del Opificio delle Pietre Dure, el cual ha suscitado continuas innovaciones técnicas y metodológicas, revolucionando los sistemas tradicionales de restauración de obras en bronce dorado.In this article the author presents the long and extensive background and history of the preservation project concerning the Florence Baptistery´s Gate of Paradise arguing that it has turned out to be one of the most complete research projects of the Opificio delle Pietre Dure. The project has brought forward continuous technical and methodological innovations which have revolutionized traditional restoration systems applied to works in gilded bronze.Fil: Ciatti, Marco. Opificio delle Pietre Dure; Florencia, Itali
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