4,930 research outputs found
Rol de la concentración de Níquel en cátodos de óxidos Mn-Ni
Se estudió el comportamiento catódico de óxidos NixMn3 - xO4 (x=0,4; 0,5; 0,6; 0,7; 0,8) en medio ácido. Se muestra la influencia del níquel en la reactividad electroquímica de los cátodos. Los mejores resultados se obtienen con NiO,6Mn2,4O4 . La reactividad de los óxidos en la reducción catódica se explica a través de la concentración de los cationes en la estructura y de la ocurrencia del proceso redox entre Ni2+ y Mn3+ de los sitios octaédricos de la espinela
Grids of Stellar Models and Frequencies with CLES + LOSC
We present a grid of stellar models, obtained with the CLES evolution code,
following the specification of ESTA-Task1, and the corresponfing seismic
properties, computed with the LOSC code. We provide a complete description of
the corresponding files that will be available on the ESTA web-pages.Comment: 8 pages, accepted for publication in Astrophys. Space Sci.
(CoRoT/ESTA Volume
High-resolution infrared spectroscopy as a tool to detect false positives of transit search programs
Transit search programs such as CoRoT and Kepler now have the capability of
detecting planets as small as the Earth. The detection of these planets however
requires the removal of all false positives. Although many false positives can
be identified by a detailed analysis of the LCs, the detections of others
require additional observations. An important source of false positives are
faint eclipsing binaries within the PSF of the target stars. We develop a new
method that allows us to detect faint eclipsing binaries with a separation
smaller than one arcsec from target stars. We thereby focus on binaries that
mimic the transits of terrestrial planets. These binaries can be either at the
same distance as the target star (triple stars), or at either larger, or
smaller distances. A close inspection of the problem indicates that in all
relevant cases the binaries are brighter in the infrared than in the optical
regime. We show how high resolution IR spectroscopy can be used to remove these
false positives. For the triple star case, we find that the brightness
difference between a primary and an eclipsing secondary is about 9-10 mag in
the visual but only about 4.5-5.9 magnitudes in the K-band. We demonstrate how
the triple star hypothesis can be excluded by taking a high-resolution IR
spectrum. Simulations of these systems show that the companions can be detected
with a false-alarm probability of 2%, if the spectrum has a S/N-ratio > 100. We
show that high-resolution IR spectra also allows to detect most of the false
positives caused by foreground or background binaries. If high resolution IR
spectroscopy is combined with photometric methods, virtually all false
positives can be detected without RV measurements. It is thus possible to
confirm transiting terrestrial planets with a modest investment of observing
time.Comment: 6 pages, 7 figure
Big data in economics: evolution or revolution?
The Big Data Era creates a lot of exciting opportunities for new developments in economics and econometrics. At the same time, however, the analysis of large datasets poses difficult methodological problems that should be addressed
appropriately and are the subject of the present chapter
Low temperature transition to a superconducting phase in boron-doped silicon films grown on (001)-oriented silicon wafers
We report on a detailed analysis of the superconducting properties of
boron-doped silicon films grown along the 001 direction by Gas Immersion Laser
Doping. The doping concentration cB has been varied up to approx. 10 at.% by
increasing the number of laser shots to 500. No superconductivity could be
observed down to 40mK for doping level below 2.5 at.%. The critical temperature
Tc then increased steeply to reach 0.6K for cB = 8 at%. No hysteresis was found
for the transitions in magnetic field, which is characteristic of a type II
superconductor. The corresponding upper critical field Hc2(0) was on the order
of 1000 G, much smaller than the value previously reported by Bustarret et al.
in Nature (London) 444, 465 (2006).Comment: 4 pages including 4 figures, submitted to PRB-Rapid Communicatio
Supramolecular chemistry of helical foldamers at the solid-liquid interface: self-assembled monolayers and anion recognition
The synthesis of a redox-active helical foldamer and its immobilization onto a gold electrode are described. These large molecular architectures are grafted in a reproducible manner and provide foldamer-based self-assembled monolayers displaying recognition properties
Evidence of electrochemical transduction of cation recognition by TEMPO derivatives
This work reports the first example of electrochemical cation binding transduction via nitroxyl groups. It shows the possibility to transduce a complexation without a pi-conjugated bridge between the redox and the host moieties. As expected, we confirm that the host/redox probe distance is a key point for transduction
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