Maximum surface coverage

However, in subsequent studies [23-25,88-90] it was demonstrated that in reality the particle deposition is not a purely geometric effect, and the maximum surface coverage depends on several parameters, such as transport of particles to the surface, external forces, particle-surface and particle-particle interactions such as repulsive electrostatic forces [25], polydispersity of the particles [89], and ionic strength of the colloidal solution [23,88,90]. Using different kinds of particles and substrates, values of the maximum surface coverage varied by as much as a factor of 10 between the different studies. 

The maximum surface coverage in these experiments after the steady state had been reached was 0.032 with argon and 0.055 with nitrogen. It is, therefore, plausible that only small changes in the surface are responsible for the changing character of the adsorption process as a result of the thermal treatment. 

Therefore, it is inferred that near the maximum surface coverage, under reducing conditions, the surface vanadium oxide species compensate for the oxygen removal by sharing oxide ions. Any effect that promotes interactions among surface vanadia species must lead to the formation of crystalline V205. 

A significant problem in surface complexation models is the definition of adsorption sites, The total number of proton-exchangeable sites can be determined by rapid tritium exchange with the oxide surface (25). Although surface equilibria are usually written in terms of one surface site, e.g. Equations 5, 6, 8, 9, adsorption isotherms for many ions show that the number of molecules adsorbed at maximum surface coverage (fmax) is less than the total number of surface sites. For example, uptake of Se(VI) and Cr(VI) ions on Fe(0H)3(am) at T ax 1/3 and 1/4 the total... 

The number of surface sites covered by an adsorbate is important in model calculations when the amount adsorbed approaches the maximum surface coverage, T x available surface sites become... 

Determined by titration (the authors refer to it as the isoelectric point). Maximum surface coverage obtained from the Langmuir isotherm. Source Ref 206. 

XPS has been used to analyze the time dependence of the fiber surface coverage. It was found that a maximum surface coverage is reached almost immediately after the start of the finishing procedure (Scheme 1) [2]. The surface silicon level reached after 30 s remains constant over the whole adsorption time. 

Based on these kinetic data a two-step process can be proposed rapid maximum surface coverage and subsequent slow diffusion into the fiber interior. 

The agreement between the results obtained either by direct measurements at 200° or indirect calculations for oxygen chemisorbed at 250° is considered as a proof of the accuracy of the thermochemical cycles which were used for the indirect calculations (49). As the temperature is increased, the maximum surface coverage by adsorbed oxygen... 

Size of these gaps could amount to the value of surface requirement for anchor groups of the modifier, namely 0.35-0.45 sq.nm for dimethylsilanes, 0.6 0.7 sq.nm for triethoxy-silanes. Published data [23] and our computation results show that the maximum surface coverage in this case is only 51-56% of the theoretical limit (see below). 

Further analysis of the experimental data requires determination of the maximum surface coverage Pahi- Various methods are available to estimate Pahi- In the present case, the best value in the region of maximum adsorption is 0.32 nmol cm and some variation with electrode charge density is observed. The latter observation is attributed to reorientation of the polar adsorbate in the electrode s field. 

Region IV and the plateau in it correspond to the maximum surface coverage as determined by micelle formation in the bulk or monolayer coverage, whichever is attained at the lowest surfactant concentration further increase in surfactant concentration does not alter the adsorption density. A schematic representation of adsorption by lateral interactions is given in Figure 7.8. 

The dynamic MC simulations depicted in Fig. 13b (curves b and c) were performed leading to fcon values of 10 and 24 (M s) respectively. The difference in maximum surface coverage of the vesicles due to the different number of binding sites (variation in annexin A1 coverage) on the surface was taken into account for the simulations. In summary, a decrease in annexin surface... 

The curves have a typical shape with a maximum at a certain concentration which corresponds to a surface concentration of about 50% of the maximum surface coverage. The maximum is caused by the competitive effect of two phenomena increase of the dilational elasticity modulus Eq with concentration and increase of the exchange of matter with increasing concentration, diminishing the effective elasticity. 

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