0000000000445322
AUTHOR
A. Villari
Parametric Excitation of Density Waves in Drifting Electron-Hole Plasmas
The effect of the electronic drift velocity on the conditions for parametric excitation in electron-hole plasmas is investigated in the two-mode approximation using a Vlasov-equations approach. The results show that when the electronic drift velocity approaches the phase velocity of the lower frequency mode of the plasma, a considerable lowering of the threshold for the onset of parametric excitation occurs, thus resulting in more favorable conditions for experimental observation of the process. The dependence of the threshold on other relevant physical parameters involved, such as the electron-to-hole mass and temperature ratios, is also investigated.
Evaluation of polyalkylcyanoacrylate nanoparticles as a potential drug carrier: preparation, morphological characterization and loading capacity.
Some physicochemical behaviours were investigated of polyethyl- (PECA) and polyisobutylcyanoacrylate (PICA), which, in recent years, have been proposed as nanoparticle colloidal systems for drug carrying. We observed the influence of preparation conditions, such as pH value and surfactant concentration, on parameters such as particle size and polymer molecular weight. Lower operating pH values (0-2) resulted in smaller nanoparticles than those prepared at pH 5.5. The polymer molecular weight was also a function of pH: low molecular weight at low pH and vice-versa. The surfactant concentration positively influenced main particle size and polymer molecular weight. These trends were independen…
Preparation and Biological Evaluation of Ethylcellulose Microspheres Containing Tolmetin
AbstractTolmetin microspheres were prepared by the coacervation process from the ethylcellulose. Microspheres were obtained both in presence and without protecting colloids, such as polyisobutilene (PIB) or ethyl-vinylacetate copolimers (EVA). The effect of these agents on the preparation, drug content, wall thickness, surface morphology, drug dissolution arid release from microspheres, were evaluated. The dissolution rate analysis was carried out also in the presence of a surfactant (Tween 80) at different pH values.In addition, microspheres containing Tolmetin as a core material were submitted to biological tests, in comparison with the free drug, to evaluate upon experimental models the …
5-Fluorouracil: various kinds of loaded liposomes: encapsulation efficiency, storage stability and fusogenic properties
Abstract This paper describes the optimization of 5-fluorouracil (5-FU) loaded liposome formulations. Four different preparation procedures were carried out, obtaining two types of multilamellar vesicles (MLVs), stable plurilamellar vesicles (SPLVs) and large unilamellar vesicles (LUVs). In this study various phospholipids were used to prepare liposomes. The lipid mixtures containing diplamitoylphosphatidylserine seemed the best for biological 5-FU delivery by presenting better encapsulation efficiency parameters, serum and storage stability, and fusogenic properties, which are an important factor prerequisite for in vivo liposome-cell interaction. The presence of cholesterol in the liposom…