Interaction attractive

Lambert, alkali promotion and electrochemical promotion, 447 XPS and AES, 254 Langmuir, 20, 306 Lateral interactions attractive, 266... 

The active ingredients in a shampoo play three fundamental roles. Some allow water to wash away the substances that make hair dirty. Others adhere to hair to impart a desirable feel and texture. The rest are emulsifiers that keep the mixture from separating into its components. To accomplish these effects, ingredients combine two types of interactions a strong attraction to water (hydrophilic) and an aversion to water (hydrophobic). It may seem that these properties are incompatible, but shampoos contain molecules that are designed to be simultaneously hydrophilic and hydrophobic. One example is sodium lauryl sulfate, our inset molecule. The ionic head of the molecule is hydrophilic, so it interacts attractively with water. The hydrocarbon tail is hydrophobic, so it interacts attractively with grease and dirt. Molecules of the shampoo associate with hydrophobic dirt particles to form hydrophilic clumps that dissolve in water and wash away. 

The analysis of Table 31.2 by CFA is shown in Fig. 31.11. As can be seen, the result is very similar to that obtained by log double-centering in Figs. 31.9 and 31.10. The first latent variable expresses a contrast between NO2 substituted chalcones and the others. The second latent variable seems to be related to the electronic properties of the substituents. The contributions of the two latent variables to the total inertia is 96%. The double-closed biplot of Fig. 31.11 does not allow a direct interpretation of unipolar and bipolar axes in terms of the original data X. The other rules of interpretation are similar to those of the log double-centered biplot in the previous subsection. Compounds and methods that seem to have moved away from the center and in the same directions possess a positive interaction (attraction). Those that moved in opposite directions show a negative interaction (repulsion). 

Another problem is the direction of pollen tube growth, which should be considered as tropism, related to attraction by the fertile ovules. Many observations of pollen tubes in the fluorescence microscope supported this suggestion—pollen tubes pass by the sterile ovules and grow in the direction of the fertile ones. The number of ovules penetrated by a pollen tube is correlated with the number of developing seeds, which supports the hypothesis about interaction (attraction) between the ovule and pollen tube (1,2,5). 

Figure 13. Schematic view of brush-type CSPs showing the chiral selector substituents oriented towards the liquid phase. Solvent molecules and the respective solvation are not shown. Stereoselective [SO-SA] interactions, attractive or repulsive, are located invariably within the heterogeneously structured chiral stationary phase.

Atomic nuclei consist of nucleons (protons and neutrons). The total number of nucleons is denoted as A and is called the mass number. The nucleus charge, z, is equal to the number of protons. The nucleus bond energy comprises a combination of the nuclear interaction (attraction) energy of the nucleons and the Coulomb interaction (repulsion) energy of the protons. The characteristic feature of the nuclear forces appears to be short-range action nucleons interact only when they are in a very close contact at a distance of about 10 13 cm. Another important feature is the incompressibility of the nucleons and, due to this, the volume of the nucleus grows in proportion to the mass number and its radius, in proportion to Al,i. 

Second, substituents on the dienophile (olefinic or azo) can adopt a position in the transition state either exo or endo to the diene system. It has been found that the endo transition state is favored significantly over the exo transition state. This preference has been attributed to secondary orbital interactions (attraction) between the diene and polar substituents on the dienophile. 

Electrostatic coulombic interactions Attractive or repulsive interactions... 

A striking demonstration of this is an atom in one molecule interacting attractively with its counterpart in a second identical molecule, as in complexes 16 and 17 in Table 6.2 [56]. In these, the attraction is between a positive a-hole on one sulfur or arsenic and a negative region on the sulfur or arsenic in the other (identical) molecule. In terms of global atomic charges, this would appear to be like attracting like. ... 

Dipole-dipole interactions Attractive forces between the permanent dipoles of polar molecules (a given polar molecule will always have partially positively charged and partially negatively charged regions). 

A possibility to generate large surface potentials, at low pH values, would be to employ values for Bt and B2 of different signs. If one would select Bt <0 and B2> 0 and a suitable cut-off distance (to avoid the divergent accumulation of anions at the interface), results similar to those obtained here would be obtained. However, this implies that the van der Waals interactions attract the anions toward and repel the cations from the interface, which contradicts the general theory of the van der Waals interactions. 

P/100, surface coverage / , AG/2.303 RT AC, free energy of adsorption R, gas constant T, temperature c, bulk inhibitor concentration n, number of water molecules replaced per inhibitor molecule f, inhibitor interaction parameter (0, no interaction + attraction and repulsion) K, constant and % P = 1 inhibited corrosion rate/uninhibited corrosion rate. 

We have made a number of assumptions in this calculation, the most notable being that the ionic solutions are ideal, in that there are no interactions (attractive or repulsive) between solute molecules. It is most unlikely that this is the case, especially in moderately concentrated solutions of ions. In order to correct for nonideality (interactions between solute molecules), we need to substitute the activities of solute molecules for their concentrations in all thermodynamic calculations. The activity (a) of a solute molecule is related to its concentration (C) by an activity coefficient (y). 

It seems likely that the cationic CPC micelles, which have a large positive charge at or near the micellar surface, interact attractively with the n-molecular orbital system of benzene, and that this interaction contributes to the fact that the solubilization constant for benzene in CPC is approximately twice as large as that in SDS micelles. A preferential interaction between cationic surfactants and aromatic solutes has been reported by several groups of investigators (25-27), and recent work in our laboratory shows that 1-hexadecyltrimethylammonium bromide micelles also solubilize benzene more effectively than do the anionic alkylsulfate surfactant micelles (28). Thus, the tendency of benzene molecules to solubilize near the surface of the cationic micelles, at low XB values, may lead to a partial saturation of surface "sites" by benzene, diminishing the ability of additional benzene molecules to bind near the surface. Such an effect could be responsible for the initial increase in activity coefficient that occurs, particularly in the CPC solutions, as Xg increases. 

Consequently B (or possibly A) rebounds and interacts again with C. These secondary encounters may be of two types either the interaction is of a repulsive kind, in which case C may abstract energy from AB broadening the vibrational energy distribution as it departs [267] or A and C may interact attractively (for example, if B and C are the same), and AC may become the molecular product rather than AB. The probability of secondary encounters will be greatest when AB is ionic or has a small reduced mass, since then the vibrational amplitude will be large the effect will be less likely where the reduced mass of the products is small. 

The physical meaning of Eq. [42] is tied to the interpretation of some of the terms, some being convoluted. The A term can be associated with dispersion interactions an increase in surface area suggests an increase in dispersion interactions (attractions) and, thus, increased solubility in octanol that in turn results in enhanced Pq/w values. A similar interpretation holds if one associates p /V with dipolarity/polarizability effects. The positive sign on the HBA term ( Umin) fot the solute suggests that the HBD acidity of water is less important than the HBA basicity of water for those molecules partitioning between phases. This implies that increased solute HBD acidity would increase the solute-water interaction. 

In the case of the fluorine derivatives, the F atom is just small enough - 1.30 A) to render F...F interactions attractive... 

There is a well-developed theory—the Derjaguin-Landau and Verwey-Overbeek (DLVO) theory—to describe the interaction between particles of a lyopho-bic colloid. This is reviewed in the texts of Hunter (1987) and Hiemenz (1986) and is based on the assumption that the van der Waals interactions (attractive forces) and the electrostatic interactions (repulsive forces) can be treated separately and then combined to obtain the overall effect of both of these forces on the particles. 

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