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Epilepsy is one of the most important neurological diseases. It concerns about 1% of the population worldwide. Despite the discovery of new molecules, one third of epileptic patients are resistant to anti-epileptic drugs and among them only a few can benefit from resective surgery. In this context, radiotherapy is an interesting alternative to the other treatments and several clinical devices exist ( e.g ., Gamma Knife ® ). The European Synchrotron Radiation Facility offers the possibility to develop new methods of radiosurgery and to study their antiepileptic effects. Here, we discuss several studies that we performed recently to test and try to understand the antiepileptic effects of X-ray synchrotron microbeams in different animal models of epilepsy. We showed a decrease of seizures after Interlaced Microbeam Radiotherapy (IntMRT) of the somatosensory cortex, known as the seizure generator, in a genetic model of absence epilepsy. These antiepileptic effects were stable over 4 months and with low tissular and functional side-effects. The irradiated pyramidal neurons still displayed their physiological activity but did not synchronize anymore. We also obtained a lasting suppression of seizures after IntMRT of the dorsal hippocampus in a mouse model of mesiotemporal lobe epilepsy. However, an important variability of antiepileptic efficiency was observed probably due to the small size of the targeted structure. Despite these encouraging proofs-of-concepts, there is now a need to adapt IntMRT to other models of epilepsy in rodents which are close to refractory forms of epilepsy in human patients and to implement this approach to non-human primates, before moving to clinical trials. [ABSTRACT FROM AUTHOR]

Electronic structures of the p-type Transparent Conducting Oxides (TCO): CuAlO2 and SrCu2O2 are calculated using the Tight Binding Linearized Muffin Tin Orbital within the Atomic Sphere Approximation method (TB-LMTO-ASA). The band structures indicate two gaps for CuAlO2 (an indirect one with ΔE≈0.45 eV and a direct one with ΔE≈1.25 eV) and one direct gap for SrCu2O2 (with ΔE≈2 eV). In both oxides the Cu states are dominant at the top of the valence band, close to the Fermi level and the existence of weak Cu–Cu bonding interactions is revealed through the Integrated Crystal Orbital Hamiltonian Population (ICOHP). The presence of such interactions suggests that for the hole doped oxides the conduction may result from the direct overlapping of the orbitals of the Cu atoms within the Cu+ networks. [Copyright &y& Elsevier]

Abstract: The results of present paper have shown that sputtering of yttrium iron garnet (Y3Fe5O12) under swift heavy ions in the electronic energy loss regime is non-stoichiometric. Here we are presenting additional experimental results for gadolinium gallium garnet (Gd3Ga5O12) as target. The irradiations were performed with different ions (50Cr (589MeV), 86Kr (195MeV) and 181Ta (400MeV)) impinging perpendicularly to the surface. As earlier, the sputtering yield was determined by collecting the emitted gadolinium and gallium atoms on a thin aluminium foil, placed upstream above the target and analyzing the Al catcher by Rutherford backscattering. Also for Gd3Ga5O12, the emission of Gd and Ga is non-stoichiometric. Sputtering appears above a critical electronic stopping power of Sth =11.6±1.5keV/nm, which is larger than the threshold for track formation, in agreement with other amorphisable materials. In addition, the angular distribution of the sputtered species was measured for Y3Fe5O12 and Gd3Ga5O12 using 200MeV Au ions impinging the surface at 20° relatively to the surface. For the two garnets the ratio of Y/Fe (and Gd/Ga) varies with the angle of emitted species and the stoichiometry seems to be preserved only for an emission perpendicular to the surface. [Copyright &y& Elsevier]

Abstract: Single crystals of gadolinium gallium garnet, Gd3Ga5O12 have been irradiated with various swift heavy ions (32S, 52Cr, 63Cu, 86Kr, 128Te, 129Xe, 181Ta, 208Pb, 238U) in the electronic stopping power regime. The extent of the induced damage is extracted from channelling Rutherford backscattering experiments and the corresponding track radii are deduced. At low beam energy (around 1.5MeV/u), the electronic stopping power threshold of damage creation is 7.2±1.2keV/nm while it is 9.3±0.9keV/nm for beam energy around 6MeV/u. The inelastic Thermal Spike model (i-TS) is used in order to calculate the track radii versus (dE/dx)e using λ, the mean diffusion length of the energy deposited on the electrons, as the only fitting parameter model. The i-TS model was extended to some other amorphizable materials like YBa2Cu3O7−δ , GeS and LiNbO3. The results, combined with previous ones extracted from BaFe12O19, Y3Fe5O12, Y3Al5O12 and α-SiO2 quartz data, showed that λ decreases when the band gap energy E g increases. By extrapolation and depending of the material, the damage threshold induced by electronic excitation can appear at beam energy as low as 10−3 to 10−1 MeV/u. [Copyright &y& Elsevier]