Anisotropy change

Salamon, Z. Tollin, G., Graphical analysis of mass and anisotropy changes observed by plasmon waveguide resonance spectroscopy can provide useful insights into membrane pro tein function, Biophys. J. 2004, 86, 2508 2516... 

Fluorescence polarisation studies on acenaphthylene labelled polyacrylic acid has demonstrated complexation occurs with polyethylene oxide to give a tightly packed and sterically restricted conformation SS. Neutralisation of the acidic groups restored the polarisation of the fluorescence and together with time resolved fluorescence analysis indicated that the motion of the probe is anisotropic. Solvent partitioning has been observed between glycol methacrylate copolymers from the fluorescence anisotropy changes of... 

Figure 11,22 Two-photon STED. The sample is excited with a ca. 100 fs laser pulse (PUMP). A time-delayed picosecond laser pulse (DUMP) is used to partially deplete the exdted state population. This causes an abrupt change in fluorescence polarization due to the preferential removal of molecules oriented parallel to the polarization direction of the PUMP. Analysis of the anisotropy change shows that it is sensitive to both the initial (pre-dumped) fluorescence anisotropy (/ u) and the pre-dumped excited state value of (a4o)- This order parameter is unobservable in conventional fluorescence experiments...

Cold drawn specimens of nylon 6 have recently been investigated by Owen and Ward who measured static moduli between — 110 C and -t-20°C, and dynamic tan d between — 70°C and -l- 110 C in a vibrating reed instrument. As can be seen from Fig. 15 the pattern of anisotropy changes with temperature, there being a minimum in o and 90, near room temperature, around the draw ratios at which X-ray diffraction indicates a transformation from an form to a more stable y form. These structural changes, and the changes responsible for the rise in the temperature of the a relaxation with orientation, prevented a detailed understanding of the mechanical deformation processes. 

Q From the ratio of (fiyv/Hcr) we find that the anisotropy changes from PMA for samples with thinner Fe layers to in-plane anisotropy for samples with thicker Fe layers. 

Figure 8.2 Simulated progress of anisotropy change from 0.5 to 0 during reactions accompanied by changes in fluorescence by factors of (a) 0.5, (b) 1 and (c) 2. In (b) an exponential record is obtained, while the otho conditions clearly show deviation from true exponential decay (J. F. Eccleston, private communication).

To first order, the frequency response of induced birefringence is constant in amplitude from low frequency to the molecular dispersion frequency in the dielectric constant where the dielectric anisotropy changes. This property is typical of all the field effects. 

Gensch, T., Gradinaru, C.C., van Stokkum, I.H.M., Hendriks, J., HeUingwerf, K.J., and van GrondeUe, R., The primary photoreaction of photoactive yellow protein (PYP) anisotropy changes and excitation wavelength dependence, Chem. Phys. Lett., 356, 3-4, 347-354, 2002. 

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