Birefringence loss, measurement

But according to de Gennes (69) such a transition is unlikely in a weak flow its experimental evidence in strong flows has been claimed by several authors from pressure losses measurements in short capillaries or in slits [Quibrahim (22), Ambari (70)] and from flow birefringence measurements in extensional flows [Pope et al. (71), Cressely et al. (72)]. It must be... 

Figure 26. Bench for s- and p- polarization measurements of the losses due to birefringence in s- and p- polarization (dex scale). The cross in the left image is due to the mirror support.

Two types of flows were investigated. At CEMEF, experiments on a plane geometry were carried out. Birefringence measurements were performed, the results of which are presented in Section III-l. Comparison with computed results will be presented in paragraph 6.2. At LRMP, flows in axisymmetric contractions were studied. We present in the next pages the experimental results obtained for presstire drops, entrance pressure losses and die swell. 

The measurements were carried out at 25°C. after quick cooling. The changes in the magnitude of birefringence and specific viscosity are also plotted in Figure 6. The parallelism among these three quantities is remarkable. This clearly indicates that the dipole moment is associated with the major axis of DNA and hence it disappears with the loss of secondary structure on denaturation. 

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