Coherence in the Ferroelectric A(3)ClO (A = Li, Na) Family of Electrolytes

Coherence is a major caveat in quantum computing. While phonons and electrons are weakly coupled in a glass, topological insulators strongly depend on the electron-phonon coupling. Knowledge of the electron-phonon interaction at conducting surfaces is relevant from a fundamental point of view as well as for various applications, such as two-dimensional and quasi-1D superconductivity in nanotechnology. Similarly, the electron-phonon interaction plays a relevant role in other transport properties e.g., thermoelectricity, low-dimensional systems as layered Bi and Sb chalcogenides, and quasi-crystalline materials. Glass-electrolyte ferroelectric energy storage cells exhibit self-charge and self-cycling related to topological superconductivity and electron-phonon coupling; phonon coherence is therefore important. By recurring to ab initio molecular dynamics, it was demonstrated the tendency of the Li3ClO, Li2.92Ba0.04ClO, Na3ClO, and Na2.92Ba0.04ClO ferroelectric-electrolytes to keep phonon oscillation coherence for a short lapse of time in ps. Double-well energy potentials were obtained while the electrolyte systems were thermostatted in a heat bath at a constant temperature. The latter occurrences indicate ferroelectric type behavior but do not justify the coherent self-oscillations observed in all types of cells containing these families of electrolytes and, therefore, an emergent type phenomenon where the full cell works as a feedback system allowing oscillations coherence must be realized. A comparison with amorphous SiO2 was performed and the specific heats for the various species were calculated

Una historia de diseño del cartel en Portugal del siglo XVII al XIX

To write an history of the design of the poster about three centuries in Portugal allows to understand how this artefact has changed over time. Usually, the result does not configure the reasons that gave rise of the poster, because they are not always visible and so, they don’t illustrate the reality in which they emerged. This article reveals a series of factors associated not only with the historical events, as well the adjacent constraints to design a poster. Portugal has in some cases a particular path with regard to the design history of the poster. To reveal this history the adopted methodology to explain this narrative will refer the technology (paper production and selection, printing techniques, use of different materials), programme (categories of posters – political, cultural and commercial – in parallel with the historical events) and authorship (anonymous and identified posters, styles and references). The article is divided in four sections, where each section is related to one century. The set of examples collected contribute to the knowledge of the history of design of the poster in Portugal.Contar una historia del diseño del cartel durante tres siglos en Portugal permite entender cómo ha cambiado este artefacto durante el tiempo. Generalmente, el resultado no configura los motivos que lo originaran, ya que no siempre son visibles y por lo tanto no ilustran la realidad en la que fueron diseñados. Este artículo revela una serie de factores asociados no solo con los acontecimientos históricos, así como las limitaciones asociadas a la realización de un cartel. Para explicar esta narrativa la metodología adoptada referirá la tecnología (papel, producción y selección, técnicas de impresión, el uso de diferentes materiales), programa (categorías de cartel –políticos, culturales y comerciales– en paralelo con los acontecimientos históricos) y autoría (carteles anónimos e identificados, estilos y referencias). El artículo se divide en tres secciones, dedicadas a cada siglo tratado. El conjunto de ejemplos recogidos contribuye al conocimiento de la historia del diseño del cartel en Portugal

First principles study of copper sulfides (for applications as photoconductors)

The Tetrahedrite’s family constitutes a complete solid-solution series, and is among the most frequent complex sulfides in Nature. This kind of structure can be generically expressed by the composition, Cu12Sb4S13. We have calculated the electronic band structure of Cu12Sb4S13 and Ag6Cu6Sb4S13 (with band gaps of 1.24 and 1.20 eV, respectively) to demonstrate that different elements occupying certain sites of the crystal structure will make a difference in what concerns the conduction process in Tetrahedrites. We will use this effect and ab initio calculations to show that the electronic properties of these compounds make them promising candidates as solar cells photovoltaic materials since not only they possess a direct band gap but their energy falls within the range of energies of photovoltaics. Moreover, we can optimize these properties by doping and substituting ions furthermore. Mechanical properties were also calculated for both compounds and will be compared.</jats:p

Cinema brasileiro e o mito “Rio de Janeiro: a cidade maravilhosa”

Esse trabalho discute a representação do “mito” da cidade maravilhosa atribuído à cidade do Rio de Janeiro através de uma reflexão sobre a produção cinematográfica brasileira contemporânea e a criação de novos paradigmas de representação e entendimento da identidade cultural brasileira. Trata-se aqui também do conceito de produção do espaço por meio da análise da representação fílmica do Rio de Janeiro no filme O Homem do Ano (The Man of the Year, José Guilherme Fonseca, 2002). Esse filme discute de forma genérica sobre vários elementos relacionados ao entendimento da vida urbana brasileira contemporânea e sua identidade cultural comentando sobre conceitos e discussões do tipo: a cidade da imaginação; a cidade como produto de certa instabilidade em relação à problemática do conceito de identidade e sua relação confusa com/no tempo e espaço; a cidade que comporta a representação imagética de todo o país; e, finalmente, a cidade que combina dois polos opostos: a cidade como um espaço moderno e civilizado e a cidade tradicional do espaço primitivo.This paper will discuss the representation of the “myth” of the marvelous city attributed to the Brazilian city of Rio de Janeiro by looking at the contemporary Brazilian film production and its creation of new paradigms for representing and understanding Brazilian cultural identity. It will also comment on the concept of production of space through the analysis of the cinematic representation of Rio de Janeiro in the film The Man of the Year (O Homem do Ano, José Guilherme Fonseca, 2002). This film generally touches on many relevant matters related to the understanding of contemporary Brazilian urban life and cultural identity commenting on the concepts and discussion such as: the city of imagination; the city as a product of a certain cultural uneasiness in relation to current concerns about identity and its confusing relationship to time and space; the city as embodying the notion of an entire country imagery; and finally, the city combining two opposing poles: the city as a civilized and modern space and the city as a traditional and primitive space

First principles calculations and experiments to determine the hydrogenation process of Cu-Li-Mg

Density Functional Theory (DFT) calculations were performed. They were firstly implemented to optimize the structure and refine the stoichiometry of the only ternary compound, CuLi0.08Mg1.92 of the Cu-Li-Mg system. Furthermore using DFT, several possible structures of CuMg2Hx were optimized. Since most of the hydrides are cubic structures or can be considered as distortions of a cubic structure, we have started calculations for CuMg2Hx (x = 4 - 6)with tetragonal and monoclinic structures, similar to those of the hydrides formed by the nearest neighbors of Cu and Mg in the periodic table: NiMg2H4 and CoMg2H5 (e.g. monoclinic C2/c and tetragonal P4/nmm, respectively). It can be concluded that the most stable configuration corresponds to CuMg2H5 with C2/c structure. We have performed several neutron scattering experiments that are in agreement with the first principles calculations.</jats:p

Experimental and first principles study of the Ni-Ti-W system

Nickel based superalloys are structural materials with a chemical composition and structure which has been developed to enable good high temperature performances leading to a wider range of applications. Their unique properties are due to their microstructure characterized by the coexistence of L12-ordered intermetallic precipitates like Ni3Al or Ni3Ti - g’ phase - in a face-centered cubic nickel based solid solution matrix, (Ni) - g phase. Solid solution strengthening at high temperatures can also be provided by the addition of refractory alloying elements, like tungsten, W. Therefore, the mechanical properties behaviour of the alloys is very strongly related to their composition and microstructures. The purpose of this work is to study the effect of composition and microstructures in a series of Ni-rich prototype alloys, Ni100-2x–Tix–Wx (in which x is in at.%), in order to understand and ultimately optimize the performance of these materials. The adopted strategy was to combine experimental studies using Neutron Diffraction, Electron Probe Micro Analysis – EPMA, Differential Scanning Calorimeter – DSC and micro-hardness measurements, with first principles calculations for structure optimization and Gibbs energies at different temperatures, for each phase, leading to thermodynamic assessment.</jats:p