Aspect ratio flexibility

The sedimentation coefficient provides a useful indicator of polysaccharide conformation and flexibility in solution, particiflarly if the dependence of on Mw is known [62]. There are two levels of approach (i) a general level in which we are delineating between overall conformation types (coil, rod, sphere) (ii) a more detailed representation where we are trying to specify particle aspect ratios in the case of rigid structures or persistence lengths for linear, flexible structures. 

The lower symmetry of nanorods (in comparison to nanoshells) allows additional flexibility in terms of the tunability of their optical extinction properties. Not only can the properties be tuned by control of aspect ratio (Figure 7.4a) but there is also an effect of particle volume (Figure 7.4b), end cap profile (Figure 7.4c), convexity of waist (Figure 7.4d), convexity of ends (Figure 7.4e) and loss of rotational symmetry (Figure 7.4f). 

Just as flexibility cannot be judged by observation alone, extraordinary mechanical strength cannot be assumed for all fibers with high aspect ratio. 

Asbestos fibers usually have a diameter of less than 0.5 microns. They may have an aspect ratio of greater than 1000, but usually at least 20, and they exhibit very high tensile strength and flexibility. The chemical and ther-... 

Later Flory (1978) extended his theory to semi-flexible particles. For that purpose he suggested that the persistence length would determine the effective aspect ratio. If the persistence length is temperature dependent then the phase behaviour will also be temperature dependent and thus, in addition, concentration dependent. He made use of Cifferri s suggestion for the temperature dependence of the persistence length... 

An aspect ratio T=a/V1/3 has been introduced [213], characterizing an effective stiffness of the chain and reflecting an interchain packing ability. The real more linear (low x) olefinic copolymers are described as the more stiff chains (with large T and a), while the more branched polyolefines (high x) as the more flexible blend components (with small r and a). 

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