Segregation of promoters

The overall behavior of the third type [mixed active phase-promoter ex (Nl Fej )Th] Is similar to the second. Preferential segregation of Fe, as compared to Nl, occurs on oxidation. A close correlation between CO conversion rate and surface Nl content has been observed. ... 

In this section, we will first demonstrate the formation of methylchlorosilanes from CH3 + a monolayers on CuaSi surfaces. The effects of promoters and the effect of surface segregation on the reaction rate and selectivity are scussed subsequently. 

Homologous recombination thus serves at least three identifiable functions (1) it contributes to the repair of several types of DNA damage (2) it provides, in eukaryotic cells, a transient physical link between chromatids that promotes the orderly segregation of chromosomes at the first meiotic cell division and (3) it enhances genetic diversity in a population. 

Moreover, segregation of nanoparticles at liquid crystal/substrate interfaces is also an effective way to promote or alter the alignment of thin nematic liquid crystal films. Depending on their concentration, size, and nature, several types of nanoparticles have been shown to induce homeotropic alignment as well as defects and remarkable defect patterns. 

Separating interlayer, which is in fact an independent phase, promotes the segregation of individual phases. 

It is important to recognise the ubiquitous presence of water in all foods. Every chapter will mention the particular impact of water as a solute, diluent and plasticiser, often converting one physical state to another and also promoting mixing or segregation of one component molecular species from another. 

Mixed oxides of Ce and other lanthanides (La, Nd) were studied by Kubsch et al. [133], who found segregation of these trivalent ions to the surface in samples calcined at 1253 K a high Eb peak in the 01s feature was observed, being ascribed to carbonates formed in the trivalent ion-rich surface. A tendency to formation of such mixed oxides was detected in (Ce,Tb)Ox supported on lanthana-promoted alumina after calcination the La XP spectrum displayed two components, ascribed to La species on the AI2O3 surface and dissolved into the Ce,Tb oxide respectively [146]. A high Eb Ols peak observed there was ascribed to both alumina 0 ions and carbonate species on La-rich zones while the (Ce,Tb) oxide gave lower Eb values. 

Model Ni/MnOx catalysts have been prepared by deposition of 150 of Ni onto an oxidized Mn disk. Subsequent reduction at 500 K in ul-trahigh vacuum results in rapid segregation of MnO onto the Ni surface. The segregation rate is ouch faster than that of Ti under identical conditions. HREELS studies reveal new C-0 stretching bands at lower frequencies, comparable to what have been observed on Rh promoted with Mn. We assign these bands to be due to CO chemisorbed on or near MnO sites. 

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