High resolution surface barrier

Somlyo There is another problem. We only have relatively low-resolution information about where these channels are. We can say that they are on the SR. But if you ask me about a 15 nm wide SR section, whether the InsP3 receptor is on the plasma-membrane-related side or not, I couldn t say. Or more to the point, where the SR is surrounding a mitochondrion, separated from it by about the same distance, I couldn t tell you whether the InsP3 release channels are adjacent and close to the mitochondrion or whether they are on the other surface, away from the mitochondrion. This will make a lot of difference whether the SR releases Ca2+ close to the mitochondrion or acts as a barrier protecting the mitochondrion from Ca2+. High-resolution information is not available. 

From the NMR tracer desorption and self-diffusion data (second and third lines of Table I), one obtains the relation Timm > TmlL. In the example given, intercrystalline molecular exchange is limited, therefore, by transport resistances at the surface of the individual crystals. Combined NMR and high-resolution electron microscopy studies 54) suggest that such surface barriers are caused by a layer of reduced permeability rather than by a mere deposit of impenetrable material on the crystal surface, although that must not be the case in general. 

STM offers the possibility of performing local spectroscopic measurements (/ vs. V curves). These measurements can be performed in-situ and ex-situ. Ex-situ UHV conditions are however more appropriate to ensure the nonconductivity of the turmeling barrier between surface and tip. Such measurements on passive films formed on Ni and Cr should provide valuable information on the conductivity of the films. This is a promising perspective for the local characterization with high resolution of the electronic properties of passive films. On the subject of the relation between chemistry at the atomic scale and atomic structure, the STM results on the passive film formed on Ni also show promising perspectives for further characterization accurate bias-dependent measurements of the terraces of the NiO oxide should provide... 

FIG. 8.12. (a) Sutface barrier detector S detector wafer, H gold surface layer, M connector, (b) a-spectrum of Am measured with a high resolution detector (Acc. to ORTEC.)... 

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