Hydrophobic solution

The diffusion of solutes in water is an important event in many biological processes. The influences of water temperature and hydropathic states of the solute are expected to be of importance in this process. A study modeling diffusion using CA was reported by Kier et al. [6]. The study revealed increases in diffusion rates with higher temperatures and higher solute hydrophobicity. More recent studies indicate that the diffusion rate may be maximum at an intermediate level of hydrophobicity and temperature [7]. 

Ishihama, Y., Oda, Y., Uchikawa, K., Asakawa, N. Evaluation of solute hydrophobicity by microemulsion electrokinetic chromatography. Anal. Chem. 1995, 67, 1588-1595. 

One of the component mechanisms is, of course, hydrophobic interactions. Retention is proportional to column hydrophobicity, and elution order is expected to generally follow solute hydrophobicity. However, it is important to keep in mind that proteins bind preferentially to columns by their dominantly hydrophobic surface. Two proteins with very similar average surface hydrophobicity may exhibit very different retention characteristics due to differences in their respective distribution of hydrophobic residues.1,2... 

Chapter 2, this entropy term is the major thermodynamic driving force for the association of hydrophobic groups in aqueous solution. Hydrophobic amino acid side chains therefore tend to be clustered in a protein s interior, away from water. 

Lipophilic ions first adsorb at the surface of the stationary phase, and the dynamically generated charge sites provide an ion exchange character that explains the retention of oppositely charged analytes [7-11]. This retention mechanism does not explain the contribution of solute hydrophobicity to retention because it should not be relevant if retention is only charge driven. It can be speculated that both mechanisms act and the extent to which one is more significant than the other depends on the experimental set-up and the nature of the IPR [12]. 

Separation of VOC fi om surfactant solution Hydrophobic membrane This process can be used to remove volatile nonaqueous phase liquids from surfactant-based soil washing and soil flushing solutions for recovery of the volatile compounds and reuse of the surfactant [108]... 

The capacity factor increases with the hydro-phobicity of the pairing ion. For hydrophilic solutes, hydrophobic pairing ions are chosen, and... 

FIGURE 1.3 Spray drying scheme of emulsified flavor solution. Hydrophobic flavor has to be emulsified into an emulsion (OAV [oil-in-water] emulsion). 

Some of the interactions that determine the three-dimensional structure of a protein molecule support a compact conformation, whereas others tend to expand the molecule. In aqueous solution hydrophobic parts of the protein are buried as much as possible in the interior of the molecule but in the adsorbed state the hydrophobic residues may be exposed to the sorbent surface, still shielded from water. Therefore, an expanded structure will be promoted upon adsorption if the compact structure in solution is stabilized by intramolecular hydrophobic bonding. More precisely, whether or not adsorbing protein molecules change their structure depends on the contribution from intramolecular hydrophobic bonding, relative to those from other interactions, to the overall stabilization of the structure in solution. In reference ( ) such an analysis of the structure determining factors has been made for HPA and RNase. It leads to the conclusion that HPA, more than RNase, is able to adapt its structure at sorbent surfaces. 

Proteins may adopt an altered conformation upon adsorption to a surface. In solution, hydrophobic sequences within proteins are folded such... 

Gotmar, G. Fornstedt, T. Andersson, M. Guiochon, G. Influence of the solute hydrophobicity on the enantioselective adsorption of beta-blockers on a cellulose protein used as the chiral selector. J. Chromatography A 2001,... 

With the increasing concentration of aluminum in the framework (with the Si/Al ratio decreasing to 1), the hydrophilic character of zeolites rises. The same relation exists between the number of exchangeable cations and the affinity for polar molecules. On the other hand, thermal stability, stability in acidic solutions, hydrophobic character of zeolites, and their affinity for nonpolar molecules increases with the decreasing aluminum concentration (increasing Si/Al ratio). 

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