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Here we wrote a short review on how time is related to the radius of curvature of the universe and on how this unique hypothesis may explain the paradoxes between quantum mechanics and general relativity. But also we explain that a possible conjecture to explain that there is almost no antimatter in the universe is that the local radius of curvature of antimatter is opposite to the local radius of curvature of matter and of the universe.

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Book Description: This new book compiles biographical sketches of top professionals in the fields of superconductivity and condensed matter, as well as research summaries from a number of different focuses in this important field. (Imprint: Nova Press)

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DOI: 10.1016/j.jnoncrysol.2009.12.009
WoS: 000275574000001
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We computed by a modified tight binding approximation, the total electronic energy of three different hybrid polymers: H-Sio(2), CH3-SiO2 and C6H5-SiO2. We made the hypothesis that the structures of these polymers are amorphous. Computational results regarding the total electronic energy and experimental data [1] on the toughness of these three hybrid polymers were compared. A good qualitative agreement was found between computations and experiments

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Ref Arxiv: 1002.1888
DOI: 10.1016/j.physb.2010.03.066
WoS: 000278673400029
Ref. & Cit.: NASA ADS
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We built graphene nanoflakes doped or not with $C$ atoms in the $sp^3$ hybridization or with $Si$ atoms. These nanoflakes are isolated, i.e. are not connected to any object (substrate or junction). We used a modified tight binding method to compute the $\pi$ and $\sigma$ density of states. The nanoflakes are semiconducting (due to the armchair geometry of their boundaries) when their are pure but the become conducting when doped because doping removes the degeneracy of the density of states levels. Moreover, we showed that the $\pi$ Fermi level and the Fermi level of both $\pi$ and $\sigma$ electrons are not superimposed for small isolated nanoflakes.

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DOI: 10.1103/PhysRevB.79.035413
WoS: 000262978200111
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10 Citations
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We present an ab initio study of the interface energies of cubic yttria-stabilized zirconia YSZ epitaxial layers on a 0001-Al2O3 substrate. The interfaces are modeled using a supercell geometry and the calculations are carried out in the framework of density-functional theory DFT and the local-density approximation LDA using the projector augmented wave PAW pseudopotential approach. Our calculations clearly establish the existence of competing growth mechanisms between 111YSZ~ 0001-Al2O3 and 100YSZ~ 0001-Al2O3 interfaces. This result is central to understanding the behavior of YSZ thin solid film islanding on 0001-Al2O3 substrates, either flat or in presence of defects.

Ref HAL: hal-00454779_v1
DOI: 10.1007/s10924-009-0137-8
WoS: 000273213500006
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We computed by a tight binding calculation taking into account hybridization, the total electronic energy of different connectivities (amorphous, fractal and linear) of (Si-(CH3)(2))(n)-(OSiO)(p)(OH)(q). We found that the total electronic energy of the amorphous connectivity was the smallest as a function of the number of atoms contained by the hybrid polymer. As the total electronic energy is linked to the stability, we may say that the connectivity of such hybrid polymer has the highest stability for the amorphous connectivity.

Ref HAL: hal-00386819_v1
DOI: 10.1016/j.jlumin.2009.04.060
WoS: 000271765300087
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2 Citations
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Sol gel obtained YZS (Yttria Stabilized Zirconia) nanocrystals have different morphologies when they grow on an α-alumina substrate after thermal treatment. When the substrate has planar defects, the nanocrystals grow in height and are narrow with a crystallographic orientation [111] in the vertical direction, while when the substrate is a perfect plane at the nanometric scale, the nanocrystals are rather extended over the substrate and do not grow in height, with a crystallo- graphic orientation [100] in the vertical direction. We present here a Monte Carlo approach which computes the actions of the substrate on the nanocrystals during thermal treatment: one action is the change in crystallographic orientation depending on the presence of defects and the other is the action on the morphology of the nanocrystals. The equivalent of thermal treatment is obtained after applying the Metropolis algorithm with adequate expressions of the energy depending on the inter-plane spacings and surface diffusion. Our numerical approach is in good agreement with the experimental results on the orientations and morphologies of the YSZ nanocrystals growing on a α-alumina substrate with planar defects [1].

Commentaires: ICL08 conference proceeding