Hydrophobicity Volume

Here v is the hydrophobic volume of the amphiphile, a is the interfacial energy and / is the chain length. The parameters describing the hydrophobic-hydrophilic interface are the mean curvature Hand the Gaussian curvature H(Figure 7.27). 

In these studies, the input sequence was represented by seven non-orthogonal physicochemical properties, namely, hydrophobicity, volume, surface area, hydrophilicity, bulkiness, refractivity, and polarity, with normalized values of (-1, 1). Thirteen-amino acid sequence windows were used, resulting in an input vector of 91 (i.e., 13 x 7) units. With the small number of training examples, the input units were only partially connected to the hidden layer in order to reduce the number of free parameters and avoid overtraining the network. The constraint was to connect each first hidden layer unit to one amino acid property exclusively, and that the size of the second hidden layer size was no larger than the first hidden layer. The output layer had exactly one unit to indicate whether the middle residue was in a membrane/non-membrane boarder. The process of development started with randomly generated architectures and resulted in 18 and 8 units in the first and second hidden layers, with a total number of free parameters of... 

Fig. 9 Monomer chemical potential in a droplet comprising monomer and hydrophobe as a function of the monomer volume fraction. (A) Effect of droplet size (r =25, 37.5, 50, 75 and 150 nm) (B) effect of hydrophobe volume fraction ( =0.005,0.01,0.02,0.04 and 0.1)...

Figure 8.2. Two molecules with an identical total hydrophobic volume (60-A at -0.6 kcal mol" ), but different best volumes identified by different colours. The molecule on the left exhibits three best volumes of...

A (red), 2SA (green) and lOA (purple), while naphthalene represents a unique group which has only the first best volume , equal to the total hydrophobic volume, and zero for the second and third ones. 

VolSurf descriptors of hydrophobic regions are hydrophobic descriptors defined in terms of the volume of the molecular envelope generating attractive hydrophobic interactions and best hydrophobic volumes that represent the best three hydrophobic interactions generated by the DRY probe and measured at —0.6 and —1.0kcal/mol. VolSurf computes hydrophobic... 

Polymersomes offer advantages for clinical therapeutic and diagnostic imaging applications. The ratio of the hydrophilic-to-hydrophobic volume fraction is the key in determining the mesoscopic formulations among micelles (spherical, prolate, or oblate) or vesicles (polymersomes) in aqueous solution [33-35]. In general, a proportion of hydrophilic block-to-total polymer from 25 to 45% favors polymersome formation, while block copolymers that have proportions greater than 45% favors micelle formation [36]. 

Xu,Z.T. Kiang, Y.H. Lee, S. Lobkovsky. E.B. Emmott, N. Hydrophilic-to-hydrophobic volume ratios as structural determinant in small-length scale amphiphilic crystalline systems Silver salts of phenylacetylene nitriles with pendant oligo(ethylene oxide) chains. J. Am. Chem. Soc. 2000. 122. 8376-8391. 

I. Penetration effect. Oil molecules penetrate into the surfactant palisade layer and expand the effective cross-sectional area, as, without increasing the hydrophobic volume of the aggregate. The increase in as due to oil penetration is minimized... 

Given that micelles are present in solution above the CMC, the most important consideration for the liquid crystal phases is the micelle shape. There are three major types, namely spheres, rods and discs . They can be described by using the packing constraint concepts (5, 41, 42). These give a simple description of the relationship between micelle shape and molecular shape. The micelles are assumed to be smooth, with only the hydrophobic volume in the micelle interior. The main molecular parameters are the hydrophobic group volume, usually taken as being equal to the alkyl chain volume (u), the area that the molecule occupies at the... 

In the basic synthesis, with the increase of g values and the reduction of surface curvature around the surfactant micelles, the cubic laid structure becomes favored over the hexagonal one [14,38]. Therefore, the enlargement of surfactant hydrophobic volume or the enhancement of hydrophobic property can easily induce the formation of MCM-48 mesostructure. The characteristics for the synthesis are ... 

TEOS is the best silica precursor in the synthesis of MCM-48, which generates ethanol during the hydrolysis. Polar ethanol tends to enter the hydrophobic zone but cannot penetrate into the surfactant micelle core [39]. The enlarged surfactant hydrophobic volume decreases the interfacial curvature around the surfactant micelles, and thus results in the formation of MCM-48. Although Ryoo and coworker synthesized MCM-48 using colloidal silica as a source, adding ethanol was also necessary [38]. 

TTie quenching rate constant, kq, is thought to be, roughly, inversely proportional to the hydrophobic volume of the host aggregate, i.e., the aggregation number - this has been predicted by theory [36,37] and has l n found experimentally valid, at least for systems with ratiter small, spherical, nucelles [35], even if in some systems it has been found to depend on [16]. 

Shrade, P, Klein, H., Egry, I. et al. 2001. Hydrophobic volume effects in albumin solutions. J. Colloid Interface Sci. 234 445 47. 

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