Temperature influence on the dipalmitoylphosphatidylcholyne - Model membranes studied by FTIR

Lyotropic liquid crystals are realized from certain concentration of amphiphilic molecules, such as phospholipids, in water. The specific interactions in which water is involved are very important for model-membrane stability. Dipalmitoylphosphatidylcholyne (DPPC) model membranes have been studied by FTIR technique at different temperatures in the spectral range {2500 - 4000} cm(-1). A Gaussian deconvolution has been performed in order to study the water behaviour from the point of view of hydrogen-bond formation between water molecules and both the hydrophilic heads of phospholipids and the components of buffer solution. This study contributes to the understanding the mechanisms which assure the model membrane stability

Transmission factor of a device containing a liquid crystalline layer between crossed polarizers

ABSTRACT The light transmission factor of a device containing a liquid crystalline layer between crossed polarizers was estimated considering the losses by reflection at the separation surfaces and the phase change induced by the liquid crystalline layer for a monochromatic radiation. The computed transmission factor of this device and that experimentally obtained were compared in this study. The differences between the intensities in the computed and experimental spectra are explained by the diffusion phenomenon in liquid crystalline layer. The changes induced by an external electric field both in the values of the main refractive indices and in birefringence determine modification for the light transmission factor of the used device. The results obtained in this study could be applied to design polarization filters in the visible range

OPTIMIZATION REACTION FOR OBTAINING SOME N-[P-(R)-BENZOYL]-L- GLUTAMINE DERIVATIVES WITH PHARMACEUTICAL ACTION

The conditions in which the obtaining reactions of some N-[p-(R)-Benzoyl]-L-Glutamine derivatives are made with the highest yield were established in this paper. Due to their antitumoral effects, the action of glutamine derivatives on the digestive enzymes has been evaluated