The modification/erosion of a-C:H (a-C:D) films was monitored in situ by ellipsometry in real time. By interpreting the ellipsometric information and combining it with measurements of the absolute D areal density changes in

the a-C:H (a-C:D) films by ion beam analysis as a function of D (H) atom fluence, we are able to distinguish three sequential stages of D interaction with hard a-C:H films. The first stage is replacement of bonded hydrogen by deuterium up to an areal density of similar to 5 X 10(15) D cm(-2) to a depth of similar to 1.4 nm from the surface. This phase is complete after a deuterium fluence of approximate to 2 X 10(18) cm(-2). The effective cross section for isotopic exchange of https://www.selleckchem.com/products/nu7441.html H with D atoms for the a-C:H layer is found to be sigma=2.0 X 10(-18) cm(2), and is close to the cross section for H abstraction MEK inhibitor side effects from a carbon surface. This may indicate that H abstraction by D from the a-C:H surface is the rate limiting step for isotope exchange in this situation. Hydrogen replacement is followed by creation of additional C-D bonds in the near-surface region and increases the D areal density by about 2.5 X 10(15) D cm(-2). By ellipsometry this process can be observed as the

formation of a soft a-C:D layer on top of the hard a-C:H bulk film, with the soft layer extending about 1.4 nm Selleckchem OICR-9429 from the surface. This stage is complete after a deuterium fluence of about 2 X 10(19) cm(-2). Subsequently, steady-state erosion of the a-C:H film takes place. Here, a soft a-C:D layer with roughly constant thickness (similar to 1.4 nm) remains on the hard a-C:H substrate and is dynamically reformed as the underlying hard a-C:H film becomes thinner. A similar sequence of processes takes place at a substrate temperature of 650 K, albeit at a much faster rate. (C) 2010 American Institute of Physics. [doi:10.1063/1.3474988]“
“Functional MRI (fMRI) is often used for presurgical language lateralization. In the most common approach, a laterality index (LI) is calculated on the basis of

suprathreshold voxels. However, strong dependencies between LI and threshold can diminish the effectiveness of this technique; in this study we investigated an original methodology that is independent of threshold. We compared this threshold-independent method against the common threshold-dependent method in 14 patients with epilepsy who underwent Wada testing. in addition, clinical results from electrocortical language mapping and postoperative language findings were used to assess the validity of the fMRI lateralization method. The threshold-dependent methodology yielded ambiguous or incongruent lateralization outcomes in 4 of 14 patients in the inferior frontal gyrus (IFG) and in 6 of 14 patients in the supramarginal gyrus (SMG).