Force hydrophobic interaction

As with SCRF-PCM only macroscopic electrostatic contribntions to the Gibbs free energy of solvation are taken into account, short-range effects which are limited predominantly to the first solvation shell have to be considered by adding additional tenns. These correct for the neglect of effects caused by solnte-solvent electron correlation inclnding dispersion forces, hydrophobic interactions, dielectric saturation in the case of... 

In filtration, the particle-collector interaction is taken as the sum of the London-van der Waals and double layer interactions, i.e. the Deijagin-Landau-Verwey-Overbeek (DLVO) theory. In most cases, the London-van der Waals force is attractive. The double layer interaction, on the other hand, may be repulsive or attractive depending on whether the surface of the particle and the collector bear like or opposite charges. The range and distance dependence is also different. The DLVO theory was later extended with contributions from the Born repulsion, hydration (structural) forces, hydrophobic interactions and steric hindrance originating from adsorbed macromolecules or polymers. Because no analytical solutions exist for the full convective diffusion equation, a number of approximations were devised (e.g., Smoluchowski-Levich approximation, and the surface force boundary layer approximation) to solve the equations in an approximate way, using analytical methods. 

Experimental studies of the thermodynamic, spectroscopic and transport properties of mineral/water interfaces have been extensive, albeit conflicting at times (4-10). Ambiguous terms such as "hydration forces", "hydrophobic interactions", and "structured water" have arisen to describe interfacial properties which have been difficult to quantify and explain. A detailed statistical-mechanical description of the forces, energies and properties of water at mineral surfaces is clearly desirable. 

The force of attraction between a dye and fiber results from the usual electronic interactions. They include ionic forces (cnulnmbic atlractinn). ion-dipole forees. hydrogen bonds, charge-transfer forces, van der Waals forces. hydrophobic interaction, and covalent bonds. 

Secondary chemical bonds such as van der Waals forces, hydrophobic interactions, electrostatic attractions, and hydrogen bonds between mucus and polymer [107] Entanglements of the polymer chains into mucus network [108]... 

Problems of intermolecular interactions and complex formation are among the major problems of chemistry and physics of polymers and molecular biology24-26,55,15°-158>. The nature of interactions between heterogeneous groups in polymer-polymer complexes may be different van der Waals and electrostatic forces, hydrophobic interactions, hydrogen and coordinate bonding. 

San Biagio PL, Bulone D, Martorana V, Palma-Vittorelli MB, 49. Palma MU. Physics and biophysics of solvent induced forces hydrophobic interactions and context-dependent hydration. Euro. Biophys. J. 1998 27 183-196. 

Figure 25 Processes occurring in the deposition of nanoparticles in flow conditions as a function of the range of interaction of forces (imi) and adhesion times. At the start, mass transport to the surface occurs, initial adhesion following through electrostatic attraction and van der Waals forces. Hydrophobic interactions can play their part as well as specific receptor-ligand interactions, which are short-range interactions. Source. From Ref. 116.

Supramolecular chemistry,54,55 the chemistry beyond the molecule, has rapidly penetrated into many areas. It involves the study of processes based on non-covalent interactions and mimics the role of nature in controlling biochemical processes by means of weak interactions such as hydrogen bonding, van der Waals forces, hydrophobic interactions and electronic interactions. 

This internal cavity which is highly hydrophobic can accommodate a wide range of guest molecules, ranging from polar compounds such as alcohols, acids, amines, and small inorganic anions to apolar compounds such as aliphatic and aromatic hydrocarbons. In all cases, the guest is bound at least partially, within the cavity of the CD. The driving forces for the inclusion complexation of CD with substrates are attributed to several factors such as van der Waals forces, hydrophobic interactions, electronic effects, and steric factors. ... 

As for van der Waals forces, hydrophobic interactions are individually weak (0.1 to 0.2 kJ moF for every square angstrom of solvent-accessible hydrocarbon surface ), but the total contribution of hydrophobic bonds to drug-receptor interactions is substantial. Similarly, the overall strength of the hydrophobic interaction between two molecules is very dependent on the quality of the steric match between the two molecules. If this is not sufficiently close to squeeze all of the solvent from the interface, a substantial entropy penalty must be paid for each of the trapped water molecules. 

The Lifshitz theo ry, which characterizes van der Waals interactions, quantitatively predicts the wide diflFerences in adsorption characteristics of various materials that are results of these interactions. Double-layer interactions appear to be well predicted by Gregory s LSA, constant-charge expression and measured zeta potentials of viruses and oxides. Other contributions to the adsorption free energies such as valence bonding, induced-image forces, hydrophobic interaction, and configurational entropy appear to be of secondary importance in our system. 

In addition to electrostatic forces, hydrophobic interactions are also implied in the interaction of proteins with soil constituents and this results in an interplay between different driving forces in adsorption. For example, hydrophobic interactions with clays can result from an electrostatic exchange of the hydrophilic counter-ions on the clay surface, leaving a hydrophobic siloxane surface (Staunton and Quiquam-poix, 1994). The rearrangement of the enzyme structure on the surface can be facilitated when hydrophobic amino acids come into contact with the clay hydrophobic siloxane layer and remain shielded from the water molecules of the solution. If this structural modification is accompanied by a decrease in ordered secondary structures, it will result in an additional increase in conformational entropy. This will lower the Gibbs energy of the system. The combination of all these different sub-processes gives rise to an irreversibility of the modification of conformation of enzymes on clay surfaces. 

The different interactions between different chemical species (molecules, ions, and radicals) do not involve covalent bonds (Charoenchaitrakool et al., 2002). The driving forces between hosts and guests, which have been proposed to justify the complex formation are hydrogen bonds, van der Waals forces, hydrophobic interactions, and the release of high energy water molecules from the cavity (Cabral Marques, 1994b Sun et al., 2006). 

Electrostatic interactions appear when the adsorptive is an electrolyte that is dissociated or protonated in aqueous solution under the experimental conditions used. These interactions, either attractive or repulsive, are strongly dependent on the charge densities for both the carbon surface and the adsorptive molecule and on the ionic strength of the solution. The non-electrostatic interactions are always attractive, and include van der Waals forces, hydrophobic interactions and hydrogen bonding. 

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