Nonlinearities in Drug Release Process from Polymeric Microparticles: Long‐Time‐Scale Behaviour

Abstract

A theoretical model of the drug release process from polymeric microparticles (a particular type of polymer matrix), through dispersive fractal approximation of motion, is built. As a result, the drug release process takes place through cnoidal oscillations modes of a normalized concentration field. This indicates that, in the case of long-time-scale evolutions, the drug particles assemble in a lattice of nonlinear oscillators occur macroscopically, through variations of drug concentration. The model is validated by experimental results.

Reducing the Risk in Controlled Drug Release by Using Tannic Acid in Liposomal Formulations

“…It is worth mentioning that even the phenomena that occur simultaneously are numerous, the release kinetics reveals a smooth evolution towars a stable state; we can affirm that the system (drug delivery polymeric matrix in the release environment) is a complex system which behaves like a self-organized structure, in which the release paths find their own equilibrium [20][21][22][23][24][25][26].…”

“…We applied the Peppas-Sahlin equation that applies best for systems that evolves until the equilibrium state is reached (the third release phase) [22]. It combines the release determined by the pure diffusion and by the diffusion triggered by relaxation of the polymer network, as a sum of two terms: the first, a diffusional term, and the second, a relaxational term, both expressed as powers of time: (2) where k D is the diffusional constant (asimilated to release rate), k R is the relaxation constant, and m is the diffusion exponent [21].…”

Solid components separation from heterogeneous mixtures through turbulence control

“…Further, the above mentioned mixtures will be felt as chaoticities of the complex fluid's flow dynamics regime, according to different scenarios of evolution toward chaos (intermittency, Ruelle-Takens, sub-harmonic bifurcations, etc.). Indeed, according to the above observations on cnoidal oscillation modes, explained by the dependence Φ ¼ Φðθ; sÞ, and following the method described in [63], the routes to chaos through intermittency and quasiperiodicity (Ruelle-Takens scenario) can be assimilated to the sections π and δ, respectively (Fig. 9), while the route to chaos through subharmonic bifurcations can be assimilated to the section μ (Fig.…”

“…Here, the mixed modes theoretically described in the above sections were experimentally observed in a complex low-temperature plasma in which a space charge structure develops in form of a fireball [63,[74][75][76][77][78]. The fireball was produced by positively biasing a tantalum disk electrode with 1 cm in diameter, introduced into a discharge plasma under the following experimental conditions: argon pressure p = 7 × 10 −3 mbar, plasma density n pl ≅ 10 8 − 10 9 cm −3 and the electron temperature kT e = 2 eV [74][75][76][77][78].…”

Characterization of Advanced Ceramic Materials Thin Films Deposited on Fe-C Substrate

“…Changes in tribological and mechanical behavior depend largely on the nature and size of metal compounds that are generally quite complex metal systems [9][10][11][12]. The scientific understanding of the friction phenomenon has advanced much on the basis of experimental results, but the complicated nature of brake friction involving very high energies, very high temperatures, very high speeds and pressures makes this process an inexact yet based on knowledge and power the understanding of the specialists [13][14][15][16][17][18][19].…”