Hydrogen absorption kinetics and optical properties of Pd-doped Mg thin films

In order to develop optical fiber hydrogen sensors, thin film materials with a high optical contrast between the metallic and hydrided states are needed. Magnesium exhibits such a contrast but cannot be easily hydrogenated at room temperature. However, thin films of Pd-doped Mg (MgP

Tumor necrosis factor α: Activity dependent expression and promotion of cortical column sleep in rats

Cortical surface evoked potentials (SEPs) are larger during sleep and characterize a sleep-like state in cortical columns. Since tumor necrosis factor alpha (TNF) may be involved in sleep regulation and is produced as a consequence of waking activity, we tested the hypothesis that direct application of TNF to the cortex will induce a sleep-like state within cortical columns and enhance SEP amplitudes. We found that microinjection of TNF onto the surface of the rat somatosensory cortex enhanced whisker stimulation-induced SEP amplitude relative to a control heat-inactivated TNF microinjection. We also determined if whisker stimulation enhanced endogenous TNF expression. TNF immunoreactivity (IR) was visualized after 2 h of deflection of a single whisker on each side. The number of TNF-IR cells increased in layers II–IV of the activated somatosensory barrel column. In two separate studies, unilateral deflection of multiple whiskers for 2 h increased the number of TNF-IR cells in layers II–V in columns that also exhibited enhanced cellular ongogene (Fos-IR). TNF-IR also colocalized with NeuN-IR suggesting that TNF expression was in neurons. Collectively these data are consistent with the hypotheses that TNF is produced in response to neural activity and in turn enhances the probability of a local sleep-like state as determined by increases in SEP amplitudes

Critical composition dependence of the hydrogenation of Mg2 +/-delta Ni thin films

The hydrogenation of metallic M

Fiber optic hydrogen detectors containing Mg-based metal hydrides

Sens. Actuators B: Chem., 2007, 123, 538-545International audienc

In situ preparation of YH2 thin films by PLD for switchable devices

We prepared epitaxial Y

Hydrogenography: An optical combinatorial method to find new light-weight hydrogen-storage materials

Hydrogenography is an advanced combinatorial and standard method used for the search of new hydrogen-storage materials to synthesize bulk samples and to use volumetric or gravimetric techniques to follow their hydrogenation reaction. Hydrogenography, with a straightforward optical setup, makes it possible to monitor hydrogen absorption and desorption simultaneously on thousands of samples under exactly the same experimental conditions. Hydrogenography is much more than a monitoring technique, as it also provides a high-throughput method to measure quantitatively the key thermodynamic properties of hydride formation. The continuous change of optical transmission with hydrogen concentration was used to measure the pressure-concentration isotherms and determine the enthalpy of hydride formation. Hydrogenography is valuable for the search for catalytic caplayers promoting hydrogen uptake, electrode materials for batteries, and smart coatings for adaptive solar collectors

Structural, optical, and electrical properties of MgyTi1−yHx thin films

The structural, optical, and electrical transformations induced by hydrogen absorption and/or desorption in Mg-Ti thin films prepared by co-sputtering of Mg and Ti are investigated. Highly reflective in the metallic state, the films become highly absorbing upon H absorption. The reflector-to-absorber transition is fast, robust, and reversible over many cycles. Such a highly absorbing state hints at the coexistence of a metallic and a semiconducting phase. It is, however, not simply a composite material consisting of independent MgH2 and TiH2 grains. By continuously monitoring the structure during H uptake, we obtain data that are compatible with a coherent structure. The average structure resembles rutile MgH2 at high Mg content and is fluorite otherwise. Of crucial importance in preserving the reversibility and the coherence of the system upon hydrogen cycling is the accidental equality of the molar volume of Mg and TiH2. The present results point toward a rich and unexpected chemistry of Mg-Ti-H compounds.

Mg-Ti-H thin films as switchable solar absorbers

The reflection and transmission spectra of Pd capped MgyTi1??y thin films (y ¼ 0:7; 0:8 and 0.9) are measured in the 0.5–5.5 eV energy range, both in the as-prepared and hydrogenated states. Upon hydrogenation these films switch reversibly from a shiny metallic state into a ‘‘black’’ absorbing one. The composition and thicknesses can be tailored to achieve high solar absorptance and low thermal emittance in the hydrogenated state. The combination of these two characteristics is interesting for the application of this material as switchable absorber in solar collectors. The use of a MgyTi1??y switchable absorber in solar collectors allows to lower the stagnation temperature from 180 to 80 1C. The collector efficiency is affected only minimally