Adsorptivity, structure effect correlations

Core hole, 34 210 core-hole lifetime, 34 215 Core level shift, C(ls), 29 13-14 Core-state excitation, 34 204 Correlation data, structure effects, 29 159-160 Correlations, adsorptivity, 29 189-190 Co9Sg, structure, 40 222 CoSiOj powders, Fischer-Tropsch synthesis, 39 288-289... 

A quantitative correlation of structural effects of four esters and four alcohols in the vapour phase transesterification on a macroreticular ion exchanger at 120°C was made using the Taft equation [441]. The authors found that rate coefficients [from eqn. (27)] yielded better correlation with steric (Es) than with polar (a ) parameters, while there was no significant difference between the correlations of the adsorption coefficients of alcohols, Kb, with both parameters. The correlations with Es yielded the slopes 1.4 and 0.6 for the reactivity of the esters and the alcohols, respectively, and —0.4 for the adsorptivity of the alcohols. The observed... 

The effect of solvent type and aminosilane concentration has been evaluated. The third component in the reaction system is the silica substrate. The surface of the silica gel carries the active sites for adsorption. The concentration of these sites varies with varying silica type, its specific surface area and pretreatment temperature. Additionally, surface adsorbed water has a clear effect on the reaction mechanism. Isotherm data, reported in the previous paragraph, only accounted for fully hydrated or fully dehydrated silica. The effect of the available surface area and silanol number remains to be assessed. Information on these parameters allows the correlation of data from studies in which different silica types have been used. In this part the effect of these parameters in the loading step is discussed. Silica structural effects on the ultimate coating, after curing, are evaluated in the next paragraph. 

We found that the IPN process is ion specific in the absence of adsorbing ions in the aqueous phase no structuring effect was observed. Some examples of structuring and non-structuring ions are presented in Fig. 11.4. In all cases, the IPN was correlated with ion adsorption, which was indirectly determined by measuring the electrokinetic zeta potential of PS films in contact with salt solutions. From our studies, several general trends were recognized ... 

To evaluate whether trends in chemisorption energies on Pt nanoparticles are consistent with the d-band model, d-band densities of states were projected out for different adsorption sites to determine the corresponding d-band centers relative to the Fermi level. No correlation was observed between the adsorption energies and site-specific d-band centers. Even though metal nanoparticles possess a continuous electronic band structure and, thus, metal-like electronic properties, their catalytic surface properties are not controlled by band structure effects but by the local electronic structure of the adsorption sites. An important conclusion from this study is that... 

It has been demonstrated that the highly parameterized meta-GGA functional M06-L is able to treat weak dispersive effects compared to standard DFT for several systems. Furthermore, van der Waals exchange-correlation functionals, namely the vdW-DF2 and vdW-DFl and KBM which has been developed by Klimes et al. in combination with localised basis sets on the basis on short-ranged pseudo-atomic orbitals have been employed to the ligand-gold interaction and obtained reasonable adsorption structure and energies. ... 

Numerous quantum mechanic calculations have been carried out to better understand the bonding of nitrogen oxide on transition metal surfaces. For instance, the group of Sautet et al have reported a comparative density-functional theory (DFT) study of the chemisorption and dissociation of NO molecules on the close-packed (111), the more open (100), and the stepped (511) surfaces of palladium and rhodium to estimate both energetics and kinetics of the reaction pathways [75], The structure sensitivity of the adsorption was found to correlate well with catalytic activity, as estimated from the calculated dissociation rate constants at 300 K. The latter were found to agree with numerous experimental observations, with (111) facets rather inactive towards NO dissociation and stepped surfaces far more active, and to follow the sequence Rh(100) > terraces in Rh(511) > steps in Rh(511) > steps in Pd(511) > Rh(lll) > Pd(100) > terraces in Pd (511) > Pd (111). The effect of the steps on activity was found to be clearly favorable on the Pd(511) surface but unfavorable on the Rh(511) surface, perhaps explaining the difference in activity between the two metals. The influence of... 

In this article I review some of the simulation work addressed specifically to branched polymers. The brushes will be described here in terms of their common characteristics with those of individual branched chains. Therefore, other aspects that do not correlate easily with these characteristics will be omitted. Explicitly, there will be no mention of adsorption kinetics, absorbing or laterally inhomogeneous surfaces, polyelectrolyte brushes, or brushes under the effect of a shear. With the purpose of giving a comprehensive description of these applications, Sect. 2 includes a summary of the theoretical background, including the approximations employed to treat the equifibrium structure of the chains as well as their hydrodynamic behavior in dilute solution and their dynamics. In Sect. 3, the different numerical simulation methods that are appHcable to branched polymer systems are specified, in relation to the problems sketched in Sect. 2. Finally, in Sect. 4, the appHcations of these methods to the different types of branched structures are given in detail. 

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