Depolarized structure factor

Figure 9.1 Depolarized structure factor for Uthium molybdenum selenate in dilute propylene carbonate solution. The measured rod length is 2 (im. (From Patterson, G.D., Ramsay, D.J., and Carroll, RJ., Depolarized light scattering spectroscopy and polymer characterization, Analytica Chimica Acta, 189, 57,1986. With permission.)...

Since rodlike polymers have a large optical anisotropy, they have a significant depolarized light scattering, which is particularly suitable for studying rotational diffusion. In the small-angle regime k L 1, the dynamic structure factor is written as ... 

Fluorescence anisotropy is the measure of emission depolarization of a fluorescent molecule excited by a polarized light [72]. Rotation of the molecule is commonly responsible for the emission depolarization. Several factors such as viscosity, temperature, structure of the surrounding solvent, and specific solute-solvent... 

Depolarized light scattering spectroscopy was applied by Degiorgio, et al. to solutions of a fiuorinated latex polymer(10). The orientations of pairs of spheres are uncorrelated, so as discussed in Section 10.4 the VH spectrum is determined entirely by the self- part of the dynamic structure factor appropriate analysis of the VH spectrum determines both Ds and the rotational diffusion coefficient Dr. Degiorgio, et al. found that Ds(4>) and Dr(4>) are both accurately described, for... 

Eugenol, like other phenolic compounds, is a structurally non-specific drug. The pharmacological action is not directly subordinated to chemical structure, except to the extent that structure affects physicochemical properties, as adsorption, solubility, pKa, and oxidation-reduction potential, factors which influence permeability, depolarization of the membrane and protein coagulation [34],... 

To visualize the depolarization fields we may consider the following idea assume we find a molecule with its absorption dipole moment in the plane of the sample. We now adjust the polarization of the excitation beam such that the fluorescence is maximized. We may assume that this happens if the electric field vector in the focus is parallel to the dipole moment. Now, if we turn the incoming polarization by 90° the dominant electric field component will not be able to excite the molecule and the presence of other field components should become visible as weak, but distinctly non-circular spots. Figure 6 shows the result of such an experiment. In Fig. 6(b) the polarization has been turned by 90° as compared to (a) as indicated by the white arrows. The bright spots become dim and their symmetry changes to a four-lobed structure. These weak structures can be made visible if the excitation intensity is increased by a factor of five [see Figs. 6(c) and (d)]. 

Beside the bactericidal function of nanosilver discussed in the literature, there are many factors that can cause the undesirable cytotoxicity effect of nanomaterials. The reason for silver s cytotoxicity should also be found in the formation of ROS, which damage the DNA and RNA of the cells by way of apoptosis. Due to the strong reduction-oxidation function (redox) of precious metals, nAg increase the ROS concentration and induce oxidation stress in the cells, initiating the peroxidation process, which causes a deformation of the cell membrane s structure, the latter s depolarization and the inhibition of the membrane enzymes activity. This leads to the loss in the integrity of the cell membrane and a disorder of the oxidative phosphorylation in mitochondria [6], which in consequence, contributes to cell degradation and leads to numerous diseases and accelerated ageing of the body [7]. 

The structure and toxic symptoms of pinnamine resemble those of anatoxin-a (11) [19,20], a potent postsynaptic depolarizing neurotoxin known as very fast death factor (VFDF), and atropine [21], a representative suppressor of the... 

It is well known that the Bruggeman EMA formula is derived by considering one of the constituents as a small sphere. A deviation from such an assumption required a modification the formula to include depolarization factor. Typically, a value of 0.333 is used as a default value in the EMA layer, which assumes a spherical shape of the inclusion. The other two extremes are 0, for a needle-like or columnar micro structure, and 1 for flat disks or a laminar microstructure. This type of transition was found for polyaniline/poly(methylmethacrylate) blend films presenting with a spherical-like microstructure at low sample concentration, whereas at relatively high concentrations the depolarization factor shifted to values closer to 1. This indicated the formation of flat microstructures due to aggregation of the polyaniline particles [8]. 

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