Ni-based catalysts obtained from perovskites oxides for ethanol steam reforming

Perovskites as host structures of cations were used in order to generate in situ active and stable catalysts for ethanol steam reforming. For this purpose,La_(1-x)Mg_xAl_(1-y)Ni_yO_3(x = 0.1; y = 0,0.1,0.2,0.3) perovskites were synthetized by the citrate method.Ni segregation is evident for a substitution level higher than 0. 2. The segregation of Ni as NiO generated species interacts with different metal-support after the reduction step. The y = 0.1 catalyst presents the highest H_2 yield value about 85% during reaction time,with low mean values of CH_4 and CO selectivities of 3.4% and 11%,respectively and a low carbon formation. The better performance of y = 0.1 catalyst could be attributed to the minor proportion of segregated phases,thus a controlled expulsion of Ni is successfully reached.

Dynamics of the phase-change material GeTe across the structural phase transition

Results of inelastic neutron scattering experinients and ab initio molecular dynamics simulations for GeTe 一 the parent compound of phase-change materials are reported. The inelastic neutron spectra of GeTe powder samples have been determined in the temperature range extending from 300 to 700 K. The phonon peaks undergo thermal shifts resulting from anharmonic effects being weaker for acoustic than optic modes. A small concentration of free charge carries arising from the presence of Ge-vacancies was found not to affect significantly the neutron weighted phonon densities of states of GeTe. The spectral pattern changes qualitatively across the structural phase transition, but the local structure of GeTe remains hardly affected, as confirmed by the analysis of temperature dependence of the pairdistribution function obtained from ab initio molecular dynamics investigations. The present theoretical studies support in a wide extent our experimental observations and also those provided by local probe methods.

Nano-confinement of biomolecules： Hydrophilic confinement promotes structural order and enhances mobility of water molecules

Molecular dynamics simulations have been used to investigate the confinement packing characteristics of small hydrophilic （N-acetyl-glycine-methylamide, Nagma） and hydrophobic （N-acetyl-leucine-methylamide, Nalma） biomolecules in large diameter single-wall carbon nanotubes （SWCNTs）. We find that hydrophilic biomolecules easily fill the nanotube and self organize into a geometrical configuration which reminds the water structural organization under SWCNT confinement. The packing of hydrophilic biomolecules inside the cylinder confines all water molecules in its core, which enhances their mobility. Conversely, hydrophobic biomolecules accommodate into the nanotubes with a trend for homogeneous filling, which generate unstable small pockets of water and drive toward a state of dehydration. These results shed light on key parameters important for the encapsulation of biomolecules with direct relevance for long-term storage and prevention of degradation.

Field-tuned quantum effects in a triangular-lattice Ising magnet

We report thermodynamic and neutron scattering measurements of the triangular-lattice quantum Ising magnet TmMgGaO_(4)in longitudinal magnetic fields.Our experiments reveal a quasi-plateau state induced by quantum fluctuations.This state exhibits an unconventional non-monotonic field and temperature dependence of the magnetic order and excitation gap.In the high field regime where the quantum fluctuations are largely suppressed,we observed a disordered state with coherent magnon-like excitations despite the suppression of the spin excitation intensity.Through detailed semi-classical calculations,we are able to understand these behaviors quantitatively from the subtle competition between quantum fluctuations and frustrated Ising interactions.

巨大磁电阻水锰矿

本书是关于有着重要工业应用的巨大磁电阻材料的专著，包含最近的理论研究和最新的实验研究结果。分别由相关的专家学者写成。因而对固体材料、应用物理、材料科学和固体化学等方面都有着重要的意义。

Dynamical properties of water in living cells

With the aim of studying the effect of water dynamics on the properties of biological systems, in this paper, we present a quasi-elastic neutron scattering study on three different types of living cells, differing both in their morphological and tumor properties. The measured scattering signal, which essentially originates from hydrogen atoms present in the investigated systems, has been analyzed using a global fitting strategy using an optimized theoretical model that considers various classes of hydrogen atoms and allows disentangling diffusive and rotational motions. The approach has been carefully validated by checking the reliability of the calculation of parameters and their 99% confidence intervals. We demonstrate that quasi-elastic neutron scattering is a suitable experimental technique to characterize the dynamics of intracellular water in the angstrom/picosecond space/time scale and to investigate the effect of water dynamics on cellular biodiversity.