Modeling the diffusion-erosion crossover dynamics in drug release.

A computational model is proposed to investigate drug delivery systems in which erosion and diffusion mechanisms are participating in the drug release process. Our approach allowed us to analytically estimate the crossover point between those mechanisms through the value of the parameter b (b_{c}=1) and the scaling behavior of parameter τ on the Weibull function, exp[-(t/τ)^{b}], used to adjust drug release data in pharmaceutical literature. Numerical investigations on the size dependence of the characteristic release time τ found it to satisfy either linear or quadratic scaling relations on either erosive or diffusive regimes.

Residual entropy and waterlike anomalies in the repulsive one dimensional lattice gas.

The thermodynamics and kinetics of the one dimensional lattice gas with repulsive interaction are investigated using transfer matrix technique and Monte Carlo simulations. This simple model is shown to exhibit waterlike anomalies in density, thermal expansion coefficient, and self-diffusion. An unified description for the thermodynamic anomalies in this model is achieved based on the ground state residual entropy which appears in the model due to mixing entropy in a ground state phase transition.

Thermodynamic and dynamic anomalies in a one-dimensional lattice model of liquid water.

We investigate the occurrence of waterlike thermodynamic and dynamic anomalous behavior in a one dimensional lattice gas model. The system thermodynamics is obtained using the transfer matrix technique and anomalies on density and thermodynamic response functions are found. When the hydrogen bond (molecules separated by holes) is more attractive than the van der Waals interaction (molecules in contact) a transition between two fluid structures is found at null temperature and high pressure.