Alternative Buffer-Layers for the Growth of SrBi2Ta2O9 on Silicon

In this work we investigate the influence of the use of YSZ and CeO2/YSZ as insulators for Metal- Ferroelectric-Insulator-Semiconductor (MFIS) structures made with SrBi2Ta2O9 (SBT). We show that by using YSZ only the a-axis oriented Pyrochlore phase could be obtained. On the other hand the use of a CeO2/YSZ double-buffer layer gave a c-axis oriented SBT with no amorphous SiO2 inter- diffusion layer. The characteristics of MFIS diodes were greatly improved by the use of the double buffer. Using the same deposition conditions the memory window could be increased from 0.3 V to 0.9 V. From the piezoelectric response, nano-meter scale ferroelectric domains could be clearly identified in SBT thin films.Comment: 5 pages, 9 figures, 13 refernece

Fermionic entanglement extinction in non-inertial frames

We study families of fermionic field states in non-inertial frames which show no entanglement survival in the infinite acceleration limit. We generalise some recent results where some particular examples of such states where found. We analyse the abundance and characteristics of the states showing this behaviour and discuss its relation with the statistics of the field. We also consider the phenomenon beyond the single mode approximation.Comment: 6 pages, 4 figures, revtex4-

Atmospheric image blur with finite outer scale or partial adaptive correction

Seeing-limited resolution in large telescopes working over wide wavelength range depends substantially on the turbulence outer scale and cannot be adequately described by one "seeing" value. We attempt to clarify frequent confusions on this matter. We study the effects of finite turbulence outer scale and partial adaptive corrections by means of analytical calculations and numerical simulations. If a von Karman turbulence model is adopted, a simple approximate formula captures the dependence of atmospheric long-exposure resolution on the outer scale over the entire practically interesting range of telescope diameters and wavelengths. In the infrared (IR), the difference with the standard Kolmogorov seeing formula can exceed a factor of two. We find that low-order adaptive turbulence correction produces residual wave-fronts with effectively small outer scale, so even very low compensation order leads to a substantial improvement in resolution over seeing, compared to the standard theory. Seeing-limited resolution of large telescopes, especially in the IR, is currently under-estimated by not accounting for the outer scale. On the other hand, adaptive-optics systems designed for diffraction-limited imaging in the IR can improve the resolution in the visible by as much as two times.Comment: A&A accepte

Lower Cretaceous (Hauterivian-Albian) ammonite biostratigraphy in the Maestrat Basin (E Spain)

Peer reviewedPublisher PD

Enhanced activity of carbon-supported Pd-Pt catalysts in the hydrodechlorination of dichloromethane

Monometallic and bimetallic catalysts with different proportions of Pd and Pt prepared by co-impregnation on activated carbon have been deeply characterized by inductively coupled plasma-mass spectroscopy, temperature-programmed reduction, 77K N2 adsorption-desorption, CO chemisorption, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. They have been tested in the gas-phase hydrodechlorination of dichloromethane (DCM) at atmospheric pressure, reaction temperatures of 150-200°C, and a space-time of 0.6kghmol-1. The presence of Pd and Pt in the catalysts produces a synergistic effect observed in terms of dichloromethane conversion and overall dechlorination, especially when both metals are in similar proportions. The results from catalysts characterization suggest that the enhanced activity is due to a significant decrease of the metallic particles size and an optimum ratio of electro-deficient to zero-valent species in the bimetallic catalysts. The catalyst with 0.90wt.% of Pt and 0.50wt.% of Pd yielded the best results. Under intensified conditions, viz. 250°C and 1.73kghmol-1, 100% DCM conversion and 98.6% overall dechlorination were obtained. This catalyst had most of its metallic particles within the range of 0.5-1nmThe authors gratefully acknowledge financial support from the Spanish Ministerio de Economía y Competitividad through the project CTM2011-28352. M. Martín Martínez acknowledges the Spanish Ministerio de Ciencia e Innovación and the European Social Fund for her research grant (BES 2009-016802

A global descriptor of spatial pattern interaction in the galaxy distribution

We present the function J as a morphological descriptor for point patterns formed by the distribution of galaxies in the Universe. This function was recently introduced in the field of spatial statistics, and is based on the nearest neighbor distribution and the void probability function. The J descriptor allows to distinguish clustered (i.e. correlated) from ``regular'' (i.e. anti-correlated) point distributions. We outline the theoretical foundations of the method, perform tests with a Matern cluster process as an idealised model of galaxy clustering, and apply the descriptor to galaxies and loose groups in the Perseus-Pisces Survey. A comparison with mock-samples extracted from a mixed dark matter simulation shows that the J descriptor can be profitably used to constrain (in this case reject) viable models of cosmic structure formation.Comment: Significantly enhanced version, 14 pages, LaTeX using epsf, aaspp4, 7 eps-figures, accepted for publication in the Astrophysical Journa

PI3Kα inhibition reduces obesity in mice

Partial inhibition of PI3K is one of the best-validated and evolutionary conserved manipulations to extend longevity. The best known health beneficial effects of reduced PI3K are related to metabolism and include increased energy expenditure, reduced nutrient storage, and protection from obesity. We have previously shown that a dual chemical inhibitor of the alpha and delta PI3K isoforms (CNIO-PI3Ki) reduces obesity in mice and monkeys, without evident toxic effects after long-term treatment. Here, we dissect the role of the alpha and delta PI3K isoforms by making use of selective inhibitors against PI3Kα (BYL-719 also known as alpelisib) or PI3Kδ (GS-9820 also known as acalisib). Treatment of mice with the above mentioned inhibitors indicated that BYL-719 increases energy expenditure in normal mice and efficiently reduces body weight in obese (ob/ob) mice, whereas these effects were not observed with GS-9820. Of note, the dose of BYL-719 required to reduce obesity was 10x higher than the equivalent dose of CNIO-PI3Ki, which could suggest that simultaneous inhibition of PI3K alpha and delta is more beneficial than single inhibition of the alpha isoform. In summary, we conclude that inhibition of PI3Kα is sufficient to increase energy expenditure and reduce obesity, and suggest that concomitant PI3Kα inhibition could play an auxiliary role

Deactivation and regeneration of activated carbon-supported Rh and Ru catalysts in the hydrodechlorination of chloromethanes into light olefins

This work analyses the deactivation of activated carbon-supported Rh and Ru (both at 1 wt%) catalysts (Rh/C and Ru/C) in the hydrodechlorination (HDC) of dichloromethane (DCM) and chloroform (TCM). The deactivation can be mainly attributed to the coverage of active metal centres by organometallic species resulting from the chemisorption of reaction products, such as olefins, at the electro-deficient metal sites. With DCM, the activity of Ru/C decreased by more than 80% after 90 h on stream at 250 °C and with a space time of 1.7 kg h mol−1. Under the same conditions, with TCM, the Rh/C and Ru/C catalysts lost 75% of activity after 84 and 54 h on stream, respectively. A regeneration treatment with air at 250 °C allowed complete recovery of the catalytic activity. After each deactivation-regeneration cycle, the selectivity to olefins increased. Therefore, HDC with the catalysts tested provides a promising way for the upgrading of chloromethanes from waste gas streams into light olefinshe authors gratefully acknowledge financial support from FEDER/ Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación/CTM2017-85498-R. M. Martín Martínez acknowledges a postdoctoral grant, 2017-T2/AMB-5668, from the Comunidad de Madrid “Atracción de talento investigador” programm