Origin surface free energy

Furthermore, different fold surface free energies for the different sectors and a maximum crystallization temperature are predicted. For details the reader is referred to the original paper. 

In section 3.6.3 we mentioned that in growth on a curved face the strain surface free energy os takes the role the lateral surface free energy tr played in the flat surface case, namely that of a barrier to the formation of the first stem. This analogy cannot be made since, in contrast to surface free energy is associated with the deposition of any stem. Therefore and because of its physical origin (the volume strain) it is closely linked with the free energy of fusion. This is... 

Aggregation because of strong inter-particle forces, originated by an excess of surface free energy, nanoparticles may easily aggregate. When hydrophobic they will clump together in polar/aqueous media such as any body fluid. This may be inconvenient with animal tests as such clumped material will not disperse,14 and in some cases even cause immediate animal death.15... 

It is important to point out that for a flat surface (a = oo, d = constant) Eq.(16) reduces to Eq.(12), the original Gray s equation. Moreover, for a fixed molecule size, d, increases as the pore size, a, decreases, and reaches a maximum when the radius of the adsorbate becomes equal to the pore radius (hypothetical case). Equation (16) is thus a more general equation than Eq.(12), and permits the dispersion component of the surface free energy for porous and non- porous materials to be determined. 

The establishment of relationships between the surface chemistry and the surface free energy of silicas is important for practical applications of these materials. Inverse gas chromatography, either at infinite dilution or finite concentration, appears to be an effective method for the detection of changes of surface properties induced by chemical or thermal treatments. Silicas of various origins (amorphous or crystalline) with surface chemistries modified by chemical (esterification) or heat treatment were compared. The consequences of these modifications on surface energetic heterogeneities were assessed. 

London Component of the Surface Free Energy of Heat-Treated Silicas. Figure 1 shows the evolution of 7sd for the different types of silicas versus heat-treatment temperature. The origin of the sample as well as the thermal treatments applied are important in determining 7sd. 

Surface free energies of hydroxylapatite and fluorapatite were determined by Busscher et al. (1987) from contact angle measurements. They found that in vacuum y ranges between 72 and 95 mJ/m. In the presence of a saturated vapor, y was found to be between 28 and 48 mJ/m. The difference in y obtained by the two methods was explained as resulting from the presence of an adsorbed film originating from the liquid droplets employed in the measuring procedure. Face-specific measurements revealed for the 001 crystal face y = 28 3 mJ/m, and y = 48 7 mJ/m on 100 for fluorapatite, and for hydroxylapatite the 001 crystal face y = 39 11 mJ/m, and y = 30 3 mJ/m on... 

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