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High-Pressure 3D C60 fcc Polymer

A new C60 polymerized face-centered cubic (fcc) phase has been obtained at 9 GPa and 55O°C. The high-pressure high-temperature polymerization process was followed in situ through synchrotron x- ray diffraction. The short lattice constant, 13.19A, displayed by the recovered samples indicates that a three-dimensional polymer has been prepared, although the determination of its crystal structure was hampered by th...

DFT study of novel 3D C60 polymers

New three dimensional (3D) C60 polymerized structures, in which each molecule adopts either one of the two standard orientations, have been investigated using the density functional theory (OFT) method. Ordered binary alloy type structures (AuCul, Au3Cu, CuPt, "A2B2") were used as prototypes in constructing 3D C60 polymerized structures, one standard orientation corresponding to the A atom and the other orienta...

3D C60 polymers with ordered binary-alloy type structures investigated via DFT

Three-dimensional (3D) C60 polymerized structures with each molecule adopting one of the two standard orientations, have been studied via density functional theory methods (DFT). Well-known ordered binary-alloy (AB) structures -AuCuI, Au3Cu, CuPt, “A2B2”-, have been usedas prototypes, in which one standard orientation corresponds to atom A and the other orientation corresponds to atom B. Inall the studied struc...

Structure determination of high-pressure C70 phases through a joint XRD/DFT study

Extended polymerization in ABC-stacked C70fullerite at high pressure and high temperature (HP-HT) had been considered impossible to achieve, in opposite to C60fullerite. Reasons invoked to explain such behavior ranged from the low molecular symmetry of C70to its low chemical reactivity, when compared to C60. Recently, however, we have shown that, indeed, C70 can form extended polymerized structures. Two novel C...

New high-pressure fullerene structures

New polymerized phases of fullerenes were prepared under high pressure and high temperature. Their crystal structures were determined through a combined experimentaltheoretical effort; x-ray diffraction methods, laboratory and synchrotron, complemented by density functional theory (DFT) modeling, were employed. Two novel C70 phases were prepared at 10GPa-270ºC and 7GPa-600ºC [1-3]. The first of these structures...

Three-dimensional fcc C60 polymer

A face-centered cubic (fcc) polymerized C60 phase has been synthesized at 9.5 GPa and 550 C. The observed short lattice constant, 13.19 Å, indicates that a three-dimensional (3D) polymer with adjacent C60 molecules covalently bonded was obtained. Possible polymerized structures, with each molecule adopting one of the two standard orientations, have been investigated through density functional theory (DFT). It w...

Reabilitação com facetas e jacket feldspáticas na zona estética : caso clínico

Reaction to fire of existing timber elements protected with fire retardant trea...

Fire safety is an important issue of buildings safety, especially when their fire load contents enhance the risks of fire deflagration. When existing timber structures are involved, the most usual way to improve its reaction to fire is to treat wood with fire retardants. This study focuses on the surface protection of existing timber roof structures against fire, through the use of Fire Retardant (FR) treatment...

Building vulnerabilities to fires at the wildland urban interface

Fires on the Wildland Urban Interface (WUI) have caused significant loss of life and colossal property and natural environment damages in numerous countries around the world. The solutions to mitigate this fire problem are complex, as it results from the fuel source changes from vegetation to structural materials in a fireprone environment and it involves the interaction of several factors that act synergistica...

Desempenho ao fogo de revestimentos retardadores de combustão aplicados sobre m...