Ap Technique

In studying the localization of eukaryotic translation initiation factors, we made use of the FR AP technique to determine whether the localized regions of eIF2/eIF2B represented dynamic centers of these proteins (Campbell et ah, 2005). 

There are three main detection modes for EAPFS within the appearance potential spectroscopy (APS) technique./31/ First, one may monitor soft-x-ray emission due to the decay of the core hole left by the primary process. This is called SXAPS-EAPFS (Figure le). Second, it is also possible to monitor Auger electrons due to the same core-hole decay, as in AEAPS-EAPFS and AMEFS-EAPFS, cf. Figure If. Third, one may measure the remaining total intensity of... 

The power of the Ap technique was explored even farther in a following paper examining the effect of transition metal alloys on OH poisoning of Pt-based electiocatalysts. Here the same analysis of water activation at the respective K edges of the alloyed transition metals in addition to the Lnm edge studies of the Pt portion of the alloy showed the extent to which different metals perform the bi-functional effect, essentially taking on the brunt of OHads to leave the Pt free for molecular O adsorption through ei-... 

As indicated above, the Ap technique has been applied to several other phenomena involving Pt-based electrocatalysts. The first report of Ap applied to operating Pt electrocatalysts was based on Hads at anodic potentials. The nature of Ha on Pt, and its contribution to the effective double layer, had long been a matter of debate. " Ap analysis of Pt Lmn XANES showed the H to be highly delocalized, and hopping between one-fold and three-fold (fee) sites on the Pt surface. While prior research had pointed to such activity, the realistic extent in respect to potential was murky due to the nature of the analytical techniques (e.g., IR spectroscopy, UHV studies, etc.) employed. The study by Teliska et al., ... 

Pt-based electrocatalysts have proven to be ideally suited to the Ap analysis primarily because of the extensive morphological characterizations (X-ray diffraction, single crystal electrochemical evaluations, UHV spectroscopies, etc.) performed over the past decades. In contrast, chalcogenide electrocatalysts are comprised of nanoscale amorphous clusters making a detailed analysis of the strac-ture/property relationships inherently difficult. In light of these considerations, we have recently applied the Ap technique to a novel mixed-phase chalcogenide electrocatalyst (RhxSy, commercially available from A-TEX, Inc). Rh Sy shows remarkable per-... 

Knowledge of information depth obtained from a surface analysis technique determines its wide use in surface analysis. Only a few attempts have so far been made to gather information depth based on APS this is one of the reasons why APS has not become a popular technique for surface analysis. The information depth obtained from APS technique correlates well with that determined by AES. 

Figure 2b shows two different XANES spectra. Here p(Ad/Pt) is the Pt Z3 edge spectrum in the presence of the adsorbate and p(Pt) the Z3 edge spectrum at some different potential or current, where the adsorbate coverage is either much smaller, or at least very different from the initial spectrum so that the effect of the adsorbate can be isolated. The Ap technique can therefore be considered a subtractive techrrique with the difference, Ap, given as ... 

We will discuss applications of the APS technique to simple as well as multicomponent systems. The results of the applications cited are compared with those from other techniques wherever available. The derivation of the DOS directly from the APS spectrum of 3d transition metals has been dealt with by various authors (Dose et al. 1981). The one-electron theory explains satisfactorily the 3d transition metal spectra, but fails when applied to the lanthanide metals. The electronic structures of the lanthanide metals and their intermetallics as obtained from APS spectra are also discussed. 

The present experience with the APS technique is quite limited. The experimental work has been narrowed down due to the non-availability of sufficient theoretical data. The main difficulty is the extraction of relevant information from the experimental data in order to correlate with the existing theoretical models. A wide scope exists for the theoretical and experimental work in this field. When the different aspects of APS are fully exploited, this spectroscopy will be accepted as a popular technique for material characterization of surfaces. 

The planar MSCs composed of a well-prepared porous Ni/Fe plate as a supporting substrate, double layers of LSCM and nanostructured LDC/Ni as an anode, a LDC layer as a diflusion barrier, a LSGM layer as an electrolyte, double layers of different ratios of SSC and SDC formed layers as a cathode were successfully fabricated by APS technique at INER. The measured power densities of the... 

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