Biomedical subjects

Tomás Sintes

Publications and source records attributed to Tomás Sintes.

3 recordsLinked to original sources

PubMed2004

Stiff polymer adsorption. Onset to pattern recognition.

We present the results of extensive off-lattice Monte-Carlo simulations of a stiff polymer chain adsorbing onto a sticky periodic stripe-like pattern of variable width. We have analyzed, in terms of the chain length and rigidity, the adsorption and the pattern recognition process as a function of the stripe width. We have seen that this process is twofold: (i) the chain adsorbs rather isotropically onto the surface at a characteristic temperature T(c) and (ii) a further reduction in the temperature is needed for the chain to reorganize and adjust to the specific pattern. Such polymer reorganization has been studied through the evaluation of the chain degree of stretching and asphericity. We have found an optimal stripe width that maximizes the stretching. We have introduced a criteria to estimate the characteristic temperature at which the pattern recognition takes place T(r)<T(c) and we have studied its dependence with the chain and surface relevant parameters.

Adsorption↗

PubMed2004

Structure factor scaling in colloidal phase separation.

The dynamical scaling hypothesis for the structure factor, S (q) , in depletion-driven colloidal phase separation is studied by carrying out Brownian dynamics simulations. A true dynamical scaling is observed for shallow quenches into the two-phase coexistence region. In such a quench, compact clusters nucleate and grow with time and there is only one characteristic length scale in the system after an initial transient period. Scaling is satisfied beyond this initial period. In contrast, deep quenches lead to fractal cluster growth, and the system is controlled by two characteristic lengths that evolve differently in time [Huang, Oh, and Sorensen (HOS), Phys. Rev. E 57, 875 (1998)]. True dynamical scaling thus cannot be expected to hold. However, an apparent scaling for the structure factor is observed over some period of time when these two characteristic length scales become comparable to each other. We compare our simulation results for the total structure factor to theoretical predictions by HOS by writing it as a product of cluster-cluster and the averaged single-cluster structure factors, each with its own characteristic length.

Journal Article↗

PubMed2004

Kinetics of phase transformations in depletion-driven colloids.

We present results from a detailed numerical study of the kinetics of phase transformations in a model two-dimensional depletion-driven colloidal system. Transition from a single, dispersed phase to a two-phase coexistence of monomers and clusters is obtained as the depth of the interaction potential among the colloidal particles is changed. Increasing the well depth further, fractal clusters are observed in the simulation. These fractal clusters have a hybrid structure in the sense that they show hexagonal closed-packed crystalline ordering at short length scales and a ramified fractal nature at larger length scales. For sufficiently deep potential wells, the diffusion-limited cluster-cluster aggregation model is recovered in terms of the large-scale fractal dimension Df of the clusters, the kinetic exponent z, and the scaling form of the cluster size distribution. For shallower well depths inside the two-phase coexistence region, simulation results for the kinetics of cluster growth are compared with intermediate-stage phase separation in binary mixtures. In the single-phase region, growth kinetics agree well with a mean-field aggregation-fragmentation model of Sorensen, Zhang, and Taylor.

Journal Article↗