Van derWaals forces

RuoffRS, TersoffJ, Lorents DC, Subramoney S, Chan B. Radial deformation of carbon nanotubes by van derWaals forces. Nature. 1993 Aug 5 364(6437) 514-6. 

I Sticking Van derWaals forces form between a surface and a gecko s spatulae. When multiplied by the spatulae s vast surface areas, the sum of the weak van der Waals forces is more than enough to balance the pull of gravity and hold a gecko in place. 

Letting go A gecko simply curls its toes when it wants to move. This reduces the amount of surface contact and the van derWaals forces, and a gecko loses its grip. 

The lack of variation of immersional heat with outgassing temperature indicates that the hexane molecules are rather insensitive to the chemical nature of the surface and are held primarily by van derWaals forces. The integral entropies of adsorption for a number of adsorbents with hexane are listed in Table III. 

Figure 3.105 Electrostatic stabilization of metal nanoparticles. Attractive van derWaals forces are outweighed by repulsive electrostatic forces between adsorbed ions and associated counterions at moderate interparticle separation.

Then the resonance transfer occurs by way of the transition dipole in the donor molecule inducing a transition dipole in the acceptor molecule. In other words, it is a dipole-induced dipole interaction. Now, readers have met this before when studying Van derWaals forces, one component being able to induce a dipole in a neighbouring molecule. This interaction has a strength that diminishes as the sixth power of the distance between the dipoles. So the probability of resonance transfer also reduces as the sixth power of the separation between the donor and the acceptor. This is a very sensitive dependence on distance. 

A uniform dispersion of CNTs in the electrospinning solution is critical for fabricating nano-composite fibers. Poorly dispersed CNTs always yield beaded morphologies, even at low concentrations. However, van derWaals forces cause these CNTs to readily aggregate, making dispersion in liquid difficult. To overcome this problem, the CNTs were treated with concentrated nitric acid, which has proven to be an effective method for improving the dispersion of CNTs in liquid. ... 

The electrons in nonpolar molecules such as alkanes are distributed more or less uniformly throughout the molecule. However, when molecules come close to one another, as they do in the liquid state, electrons in one molecule can become transiently polari2Ed by electrons in a neighboring molecule, resulting in a nonuniform distribution of electrons. One molecule induces a temporary dipole in the other (Figure 4.17). The induced dipoles interact by weak attractive forces called van derWaals forces or London forces. 

Three types of relatively weak intermolecularforces are hydrogen bonding, permanent dipole-dipole forces and van derWaals forces. 

Bromine is a liquid at room temperature. Weak van der Waals forces hold the bromine molecules together. Describe how van derWaals forces arise. [5]... 

The hydrogen bonds and van derWaals forces between the base pairs in part of a DNA molecule are broken. 

The tertiary structure of a protein arises from furtherfoldingofthe secondary structure and its stabilisation by bonds and intermolecularforces between the R groups (disulfide bonds, ionic bonds, hydrogen bonds and van derWaals forces). 

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