Coil-shaped structures

Fig. 14. TEM picture of a single layered helix-shaped. structure a 1.3-nm diameter helix coils around the...

Fig. 4. Representative structures of the distinct types of coil shapes, viewed along the //-solenoid axis. The structures shown are limited to two coils. The /1-strands are shown as red arrows connected by loops. The side chains are shown in the ball-and-stick representation and colored gray.

Linear polyacrylamides in solution adopt nearly random coil configurations that are partially permeable (draining) to solvent. The coils are unassociated in dilute solution. The average shape of the isolated coils has been described as an ellipsoidal or bean-shaped structure (58). The individual chains are quite flexible, as is common with most vinyl polymers. This is indicated from several parameters shown in Table 2, such as the persistence length, steric hindrance parameter (a), and characteristic ratio (Cco)- The persistence length of 1.52 nm for poly(acrylamide) in water is quite similar to the average intrinsic (bare) persistence length ( 1.4 nm) of many vinyl polymers (59). 

DNA and proteins are sometimes referred to as the polymers of life. They are more complex in nature and performance than cellulose and starch, and demand a separate examination. In the Uvtng cell, both DNA and proteins take very specific 3-D structures, and do not form either the random coils or the rod-shaped structures of synthetic polymers. The following subsections will describe a few characteristic structures and motions of these natural polymers. 

For adsorption of a PAH layer to particles precoated with multilayers, the adsorption isotherm monitored by the relaxation rate is dominated by an immobilisation contribution, while no release of water as in the monolayer case is detected. Fig. 25 shows the monotonous increase of AR2sp (compare to Fig. 23 for monolayers). The effect of salt on the adsorption process was again an increase of the water immobilisation, similar to the findings for the adsorption of the first monolayer. Conclusions on the structure (rod or coil shape) and hydration of an... 

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