First-principles predictions of low-energy phases of multiferroic BiFeO3

We used first-principles methods to perform a systematic search for potentially-stable phases of multiferroic BiFeO3. We considered a simulation cell compatible with the atomic distortions that are most common among perovskite oxides, and found a large number of local minima of the energy within 100 meV/f.u. of the ferroelectric ground state. We discuss the variety of low-symmetry structures discovered, as well as the implications of these findings as regards current experimental (e.g., on thin films displaying {\em super-tetragonal} phases) and theoretical (on models for BiFeO3's structural phase transitions) work on this compound.Comment: 14 pages, 9 figures, accepted in PRB (contains small changes in the text with respect to the first version

Thermal properties of metal-metal bonded Pd(I) complexes supported onto porous Vycor glass

Thermal behavior of the complexes Pd2(dppm)2Cl2, Pd2(dppm)2(SnCl3)Cl and Pd2(dppm)2(SnCl3)2 (dppm = bis[diphenylphosphino(methane)], ((C6H5)2PCH2P(C6H5)2) in the solid state and immobilized onto porous Vycor glass was studied. Similar decomposition mechanisms were observed for the solid and immobilized complexes, with a small thermal stabilization upon immobilization. The decomposition products were characterized by X-ray diffractometry, Raman and diffuse reflectance infrared spectroscopy, which indicated the presence of a mixture of metallic palladium and oxidized species such as PdO,condensed phosphates, SnO2 and SnP2O7. According to X-ray diffractometry, the decomposition products of the immobilized complexes presented higher amounts of PdO than the solid-state residues, probably as an effect of interactions with silanol groups present in the glass surface.Estudos dos complexos Pd2(dppm)2Cl2, Pd2(dppm)(SnCl3)Cl e Pd2(dppm)2(SnCl3) (dppm = bis[diphenylphosphino(methane)], (C6H5)2PCH2P(C6H5)2) por análise termogravimétrica (TG), no estado sólido e imobilizados no vidro poroso Vycor, são descritos. Os mecanismos de decomposição dos complexos no estado sólido e imobilizados no vidro poroso Vycor são similares e apenas uma ligeira estabilização é observada mediante a imobilização. Os produtos de decomposição foram caracterizados por difração de raios-X, espectroscopias Raman e de Refletância difusa no infravermelho, indicando a presença de uma mistura de paládio metálico e espécies oxidadas tais como PdO, fosfatos condensados, SnO2 e SnP2O7. Os produtos de decomposição dos complexos imobilizados no PVG apresentaram quantidades mais elevadas de PdO do que os resíduos no estado sólido, segundo a difração de raios-X, em virtude provavelmente da ocorrência de reações com grupamentos da superfície do vidro, bem como pelo fato de que as moléculas adsorvidas se encontram isoladas umas em relação às outras.263269Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Thermal Properties Of Metal-metal Bonded Pd(i) Complexes Supported Onto Porous Vycor Glass.

Thermal behavior of the complexes Pd2(dppm)2Cl2, Pd2(dppm)2(SnCl3)Cl and Pd2(dppm)2(SnCl3)2 (dppm=bis[diphenylphosphino(methane)], ((C6H5)2PCH2P(C6H5)2) in the solid state and immobilized onto porous Vycor glass was studied. Similar decomposition mechanisms were observed for the solid and immobilized complexes, with a small thermal stabilization upon immobilization. The decomposition products were characterized by X-ray diffractometry, Raman and diffuse reflectance infrared spectroscopy, which indicated the presence of a mixture of metallic palladium and oxidized species such as PdO,condensed phosphates, SnO2 and SnP2O7. According to X-ray diffractometry, the decomposition products of the immobilized complexes presented higher amounts of PdO than the solid-state residues, probably as an effect of interactions with silanol groups present in the glass surface.80263-

Implantación de un sistema de cálculo simbólico en el primer curso de matemáticas

Con la ayuda de un sistema de cálculo simbólico, se ofrecieron actividades en donde los conceptos fueron estudiados usando diversos sistemas de representación y las potencialidades de la calculadora como instrumento transformador del modo de representación, instrumento de verificación e instrumento de visualización, fueron usadas para trabajar la dupla expresión-contenido

Habitación de interés social y participación colectiva: El caso de la Cooperativa habitacional y mixta Shangri-lá en Rio Janeiro

3º congresso – As múltiplas Faces da Arquitetura Contemporânea de 2016 – As múltiplas Faces da Arquitetura Contemporânea – foram apresentados pelos/as estudantes da disciplina de Crítica e História da Arquitetura e da Cidade IV sob orientação da professora Andreia Moassab, do curso de Arquitetura e Urbanismo da Universidade Federal da Integração Latino-americana – UNILA. O congresso é parte da avaliação final da disciplina, no qual os/as estudantes apresentam a sua versão e dialogam com autores/as e textos de referência sobre a arquitetura nas últimas décadasEn esta presentación mostraremos los procesos, logros, dificultades y desafíos de la producción y reproducción de ciudad a partir de la experiencia de la Cooperativa Habitacional y Mixta Shangri-lá, al oeste de Río de Janeiro tras la vivencia de 29 familias que, con su participación y protagonismo, constituyeron tal cooperativa consiguiendo así realizar sus viviendas. Entendemos esta iniciativa como un medio de apropiación del espacio urbano por su valor de uso y por el sentido de pertenencia generado a partir de la construcción popular del barrio y su posterior, por sus habitantes. Así, el valor de uso de la vivienda y la cooperativa se presentan como medio integrar a la comunidad, en un contexto de carencia, desarrollándose, así como una posibilidad para hacerse con sus derechos por vivienda y acceso a la ciuda

Evaluación del Bioinsumo de Fique Pulverizado (Furcraea spp) para el Control in vitro de Phytophthora infestans en papa (Solanum tuberosum L)

The objective of this research was evaluating the antifungal activity of spray-dried Fique (Furcraea spp) for in vitro control of Phytophthora infestans in potatoes (Solanum tuberosum L). The optimal drying process variables studied were the entry temperature and air velocity of 140 °C and 60 m/s. The product obtained was amended in an agar medium tomato which was placed in petri containers, inoculated with 1.2 cm in diameter of pathogens discs. The optimum treatment inhibited 100% growth of the pathogen. Also, a reduction of water activity of 37.4% was achieved. This allowed increasing its preservation. The results showed that the technique is highly favorable for the conservation of bio-products of fungal properties

Musical preferences of Brazilian high school students

Music is considered a vital element in young people’s lives. It functions as an important means for expressing the emotions and feelings they experience in a daily basis. As such, this study explores the music preferences of high school Brazilian students (N = 940), 530 female (56.9%) and 410 male (43.1%) participants between 14 and 20 years old (M = 16.14 years old, SD = 1.22). The main instrument for data collection was the Questionnaire on Musical Style Preferences, which was adapted to the Brazilian context and encompassed 33 different music styles. A principal component analysis resulted in five dimensions representing different musical styles: (1) Intense, (2) Unique, (3) Sophisticated, (4) Contemporary, and (5) Mellow. The results of this study reinforced theory of the five-factor model of musical preference. Results also suggest that Mellow music was the most preferred while Sophisticated music was the least preferred among participants. Regarding gender, male participants showed a greater preference towards Contemporary, Intense, and Sophisticated music, whereas women generally preferred Mellow and Unique. Regarding age, participants under 20 years old showed a greater preference towards Mellow musical styles as compared to older participants. On the one hand, regression analyses showed that preferences towards Intense music decrease with age. On the other hand, gender was a better predictor for music preferences than age. Although the results of this study correspond to those of previous studies, more research studies are necessary to further explain musical preferences within the Brazilian contex