RESUMO
We show that spin-density separation in a Bose gas is not restricted to 1D but also occurs in higher dimensions. The ratio (alpha) of the intraspecies atom-atom interaction strength to the interspecies interaction strength strongly influences the dynamics of spin-density separation and the elementary excitations. The density wave is phononlike for all values of alpha. For alpha < 1, the spin wave is also phononlike. The spin waves have a quadratic dispersion in the alpha=1 coupling regime, while in the phase separated regime (alpha > 1) the spin waves are found to be damped. The dynamical structure factor reveals two distinct peaks corresponding to the density and spin waves for alpha < or =1. For alpha > 1 there is only one dynamical structure factor peak corresponding to the density wave.
RESUMO
We have studied the interaction of 5,5-diphenylhydantoin (5,5-dph), an anticonvulsant drug, with erythrocyte membrane lipids and proteins using IR spectroscopic technique. The local lateral order parameter, which is directly related to the lipid packing density, has been found to be elevated due to 5,5-dph binding. This increase has been accounted for on the basis of relaxation of local discontinuity in orientational order (defects). The transition towards an ordered structure is further supported by our experimental results which exhibit a decrease in the hydrocarbon chain mobility. The reorganization of the polar head groups due to 5,5-dph-lipid interaction leads to the absence of the bands at 1150 cm-1 (C-O stretch or C-O-C antisymmetric stretch) and 1085 cm-1 (C-O-P stretch or PO2- symmetric stretch). These bands are associated with the phospholipid head groups in erythrocyte membrane. Significant intensity changes in amide I (1650 cm-1) and amide II (1520 cm-1) have been explained using the concept of transition dipole moment coupling between C-N and N-H vibrational modes of amide II.
