Investigating Limits in Exploiting Assembled Landslide Inventories for Calibrating Regional Susceptibility Models: A Test in Volcanic Areas of El Salvador

This research is focused on the evaluation of the reliability of regional landslide suscep- tibility models obtained by exploiting inhomogeneous (for quality, resolution and/or triggering related type and intensity) collected inventories for calibration. At a large-scale glance, merging more inventories can result in well-performing models hiding potential strong predictive deficiencies. An example of the limits that such kinds of models can display is given by a landslide susceptibility study, which was carried out for a large sector of the coastal area of El Salvador, where an appar- ently well-performing regional model (AUC = 0.87) was obtained by regressing a dataset through multivariate adaptive regression splines (MARS), including five landslide inventories from volcanic areas (Ilopango and Coatepeque caldera; San Salvador, San Miguel, and San Vicente Volcanoes). A multiscale validation strategy was applied to verify its actual predictive skill on a local base, bringing to light the loss in the predictive power of the regional model, with a lowering of AUC (20% on average) and strong effects in terms of sensitivity and specificit

In Situ Raman Study of Nickel Oxide and Gold-Supported Nickel Oxide Catalysts for the Electrochemical Evolution of Oxygen

An in situ Raman spectroscopic investigation has been carried out to identify the composition of the active phase present on the surface of nickel electrodes used for the electrochemical evolution of oxygen. The electrolyte in all cases was 0.1 M KOH. A freshly polished Ni electrode oxidized upon immersion in the electrolyte and at potentials approaching the evolution of oxygen developed a layer of γ-NiOOH. Electrochemical cycling of this film transformed it into β-NiOOH, which was observed to be three times more active than γ-NiOOH. The higher activity of β-NiOOH is attributed to an unidentified Ni oxide formed at a potential above 0.52 V (vs Hg/HgO reference). We have also observed that a submonolayer of Ni oxide deposited on Au exhibits a turnover frequency (TOF) for oxygen evolution that is an order of magnitude higher than that for a freshly prepared γ-NiOOH surface and more than 2-fold higher than that for a β-NiOOH surface. By contrast, a similar film deposited on Pd exhibits a TOF that is similar to that of bulk γ-NiOOH. It is proposed that the high activity of submonolayer deposits of Ni oxide on Au is due to charge transfer from the oxide to the highly electronegative Au, leading to the possible formation of a mixed Ni/Au surface oxide. © 2012 American Chemical Society