High hydrophilicity

A drop of an aqueous solution of the mixture to be separated is now placed near the bottom of the paper strip and allowed to evaporate in the air. The strip is now again suspended in the closed cylinder, but with the bottom of the strip just immersed in the solvent. The capillary action of the paper will cause the solvent to rise steadily up the strip, and during this process the solvent, which now contains the mixture in solution, is continuously extracted by the retained water molecules in the paper. A highly hydrophobic (water-repellent) solute will move up closely behind the solvent-front, whereas a highly hydrophilic solute will barely leave the original point where the drop of the mixed solutes in solution has been dried. In an intermediate case,... 

Alkali sihcates are used as components, rather than reactants, in many appHcations. In many cases they only contribute partially to overall performance. Utility factors are generally not as easy to identify. Their benefit usually depends on the surface and solution chemical properties of the wide range of highly hydrophilic polymeric siUcate ions deUverable from soluble sihcate products or their proprietary modifications. In most cases, however, one or two of the many possible induences of these complex anions cleady express themselves in final product performance at a level sufficient to justify their use (102). Estimates of the 1995 U.S. consumption of sodium sihcates are shown in Table 6. 

The first synthesis of amphiphilic porphyrin molecules involved replacement of the phenyl rings in TPP with pyridine rings, quaternized with C2QH 2Br to produce tetra(3-eicosylpyridinium)porphyrin bromide (3) (36). The pyridinium nitrogen is highly hydrophilic the long C2Q hydrocarbon serves as the hydrophobic part. Tetra[4-oxy(2-docosanoic acid)]phenyl-porphyrin (4) has also been used for films (37). 

Drugs that are too highly hydrophilic are often absorbed rather poorly from the gastrointestinal tract. It is sometimes possible to circumvent this difficulty by preparing esters of such compounds so as to change their water lipid partition characteristics in order to enhance absorption. Once absorbed, the esters are cleaved by the numerous esterase enzymes in the bloodstream, releasing free drug. 

There are cationic, anionic, and non-ionic micelles. Divalent metal ions having positive charges are highly hydrophilic and cannot be incorporated into cationic micelles. Anionic micelles tend to form water insoluble salts with divalent metal ions. Interactions of non-ionic micelles with divalent metal ions appear to be small. Thus incorporation of a divalent metal ion into a micelle to form a catalytic center... 

The same procedure has been employed to increase the hydrophobic character of cellulose, by introducing fluorine-containing groups, e.g., 2,2-difluoroethoxy 2,2,2-trifluoroethoxy and octafluoropentoxy. Incorporation of hydrophobic moieties into cellulose is expected to increase the polymer compatibility with other materials, e.g., synthetic polymers. Note that an important part of incompatibility is due to the highly hydrophilic character of cellulose. Decreasing this character is expected to affect Tg of the derivative, as shown by cellulose propionate/octafluoropentoxy acetate (total DS = 3.0, partial DS in each moiety = 1.5), whose Tg is only 53 °C. The products are more stable than their fluorine-free counterparts, and the terminal CF2 - H group affects Tg much less than OH-substituted trifluoroethoxy celMose derivatives [196,197]. 

The surfactant dienes 90 and 91 (Figure 4.3), analogs to commercially available sodium dodecyl sulfate (SDS) and dodecyl maltoside, react rapidly with highly hydrophilic and reactive triazoline dione 92 in water at 25 °C forming, quantitatively, the corresponding adducts. The Diels-Alder reactions with less potent dienophile 93 gave, similarly, quantitative yields in 0.5 h and 3 h with 90 and 91, respectively. 

Obviously, water, aqueous solutions of salts, and mixtures of highly hydrophilic solvents have also been found to be solubilized in the micellar core [13,44]. The maximum amount of such solubilizates that can be dissolved in reversed micelles varies widely, strongly depending on the nature of the surfactant and the apolar solvent, on the concentrations of surfactant and of additives, and on temperature [24,45-47]. 

Chiari, M Micheletti, C Nesi, M Fazio, M Righetti, PG, Towards New Formulations for Polyacrylamide Matrices A-Acryloylaminoethoxyethanol, a Novel Monomer Combining High Hydrophilicity with Extreme Hydrolytic Stability, Electrophoresis 15, 177, 1994. Chiari, M Righetti, PG, New Types of Separation Matrices for Electrophoresis, Electrophoresis 16, 1815, 1995. 

The yield of this (3-glucosidation would be controlled by the equilibrium of the coordination form of the enzyme. As illustrated in Fig. 3, the reaction site of the enzyme is proposed to be highly hydrophilic. To confirm the relationship... 

Here A and X represent a highly hydrophilic and hydrophobic anion, respectively, equilibrium concentrations of which in the other phase are practically zero. Typical examples are chloride and tetrakis (4-chlorophenyl)borate anions, respectively. 

The negative ClogP term shows that highly hydrophilic molecules for this data set would present better inhibitory activities against topo I. Two compounds (Ri = R3 = R4 = R5 = H, R2 = NO2 and Ri = R3 = R4 = R5 = H, R2 = F) in Table 4 for the development of QSAR Eq. 6 were deemed to be outliers on the basis of their deviation (>2s). The outlier (Ri = R3 = R4 = R5 = H, R2 = NO2) is much more active than expected, by three times the standard deviation. This may be due to the formation of nitro anion radicals that interact with DNA [48]. The other derivative (Ri = R3 = R4 = R5 = H, R2 = F) is... 

Since water is the preferred solvent both in industrial technologies and biomedicine, the development of highly hydrophilic metal colloids has been a key step for a number of recently reported practical applications [182,203]. 

Only recently, we have shown experimentally for a selection of neutral ionophores and carefully purified, typical PVC plasticizers that in absence of ionic sites Nernstian EMF responses could not be obtained [55]. For plasticizers of low polarity no EMF responses were observed at all. Transient responses due to salt extraction even with the highly hydrophilic counterion chloride were observed in the case of the more polar nitrobenzene. Lasting primary ion-dependent charge separation at the liquid liquid interfaces of ISEs, resulting in a stable EMF response, seemed therefore only possible in the presence of ionic sites confined to the membrane phase. Because membranes free of impurity sites... 

Faujasites are highly hydrophilic materials. In the transformation of apolar compounds such as hydrocarbons, all other molecules have higher polarity, so the rate of transformation is seriously decreased because the more polar products adsorb preferentially on the zeolite. This was a serious problem in the oxidation... 

As already mentioned, some lubricants can be difficult to remove by washing and surfactants are often added to overcome this problem [463]. Lubricants can impair fastness properties, particularly those of disperse dyes. They may influence the uptake of dyes either positively or negatively, although seldom seriously except where it results in unlevelness. For example, knitting oils can increase the yield of relatively oleophilic reactive dyes on cotton and yet with highly hydrophilic types they may cause dye-resist effects [467]. 

An alumina matrix may be prepared with high pore density (more than 60 %) and pore diameters ranging from 5 to 250 nm. Ruiz-Hitzky et al. [214] immobilized GOD in nanoporous alumina membranes with regular hexagonal arrays of highly ordered cylindrical pores aligned perpendicularly to the membrane surface. GOD was anchored in the membrane by the highly hydrophilic chitosan biopolymer. Full activity was maintained for at least 50 hours. 

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