Simulação computacional de materiais bidimensionais: funcionalização de defeitos extensos no grafeno e retenção de contaminantes por argilominerais

In this work are considered two bidimensional systems, with distints chacacteristcs and applicabilitys. Is studied the adsorption of transition metals (MT) Fe, Co, Mn and Ru in extended defects, formed by graphene grain boundaries. First in pristine graphene The hollow site of carbon hexagon, in pristine graphene, are the most stable for MT adsorption. The Dirac cone in eletronic structure of graphene was manteined with the presence of MT. For the considered grain boundaries the MT has a greater stability for absorption in the grain boundaries sites in comparison with pristine graphene. Through the energy barrier values, are observed diffusion chanels for MT localized on the grain boundaries. This diffusion chanels indicate a possible formation of nanolines of MT in graphene. For the first stage of the nanolines, ate observed a better stability for the system with greater MT concentration, due to MT-MT interactions. Also, due to the magnetic moment of the MT, the nanolines show a magnetization. For the most stable configurations the system are metallics, particularly for Fe the band structure indicates an anisotropic spin current. In a second study, are considereted the retention capacity for metallic contaminants Cd and Hg in clayminerals, kaolinite (KAO) and montmorillonite (MMT). Through the adsorption energies of contaminantes in the clayminerals, was observed a increase in stability with the increase of contaminants concentration, due to the interaction Cd-Cd and Hg-Hg. Also, was observed that KAO has a strong interaction beteween monolayers than MMT. In this sence, for the adsoption process of contaminantes in the natural form of KAO and MMT, the latter has a better retention capacity, due to the small net work for contaminant intercalation. However, when the modification of clayminerals, with molecules that increase the spacing between monolayers, exist a optimal condition, which the contaminant absorption are more stable in KAO system than in MMT. In the Langmuir adsorption model for the clayminerals in the optimal monolayer spacing, the retention capacity for Cd and Hg in KAO system are 21% greater than in MMT system. Also, for the X-ray Absorption Near Edge Spectroscopy (XANES) for the K edge of Cd and Hg, are found a positive shift of absorption edge with the decreasing of monolayer spacing. This result indicates a possible way to determine the concentration of adsorbed contaminats in relation to unabsorbed ones, from the decomposition of experimental XANES in the obteined spectras.

O ensino de arte pós-moderno na arte de Daniel Francisco de Souza

This thesis presents a research that links cultural history and visual culture in a sociobiographical approach. It gives a “political treatment” to the educational experience in the transition of art teaching from the modern to the postmodern. By taking into account my experiences as an educator and the poetic practice in Daniel Francisco de Souza’s visual art, I propose a dialogue with his art and a series of visual narratives this artist/student produced at the time of his education and recently. Such visual narratives were taken as research source and research subject. They were created in a rural setting in dialogue with formal art teaching in two phases: 1992–6, when Daniel Fran cisco attended elementary school in the rural area of Uberlândia, MG; and 2008–10, when he attended Visual Arts graduation at Federal University of Uberlândia city. I analyze historical processes related to art and teaching, from the early sixteenth century to the present times, to realize residues in students’ poetic experiences. I relate Brazilian educational public policies with experi- ences in that rural school. I try to show the extent to which our educational practices triggered experiences — from ones common to intense ones — and promoted forms of “emancipation-knowledge” or “regulation-knowledge” and how the “selective tradition” was and how art predetermined history images gave way to everyday visual references, pointing to the “broad field” of visual culture. I make an effort to show Daniel Francisco’s work as an adult by tak- ing it according to different approaches. In a poetic reading, first, I emphasixe the material and the symbolic in his art. In a second look, I approach his work through the intertwining experiences of three characters from different times and places that participated in the making of his art: the artist farmer, the artist teacher and the teacher researcher. I assume the existence of a mutual cultural incompleteness in these three characters; which means that parts of their “structures of feeling” built on the interrelationship among them are part of the artist’ work as a historical content decanted. Thirdly, I demonstrate how the artist sees his place as a key re ference to his poetic creation. His work does not reflect the rural bucolic as something untouched. In showing the difficulty in distinguishing the archaic residual, I identify emerging issues in his work. I conclude that the artist — Daniel Francisco — and the researcher — myself — present maverick features: both are scavengers; their productions approach the working with scraps in art and in the academy; even momentarily, they live in exile in the warmth of the borders or the edges, from where one sees the center clearly. In these spaces, when certain structures and normative codes enter into coalition, they fragment pre-established strategies and stimulate the creation of survival tactics.