Biomedical subjects

Angelo Cacciuto

Publications and source records attributed to Angelo Cacciuto.

5 recordsLinked to original sources

PubMed2006

Confinement-driven translocation of a flexible polymer.

We consider the escape of a flexible, self-avoiding polymer chain out of a confined geometry. By means of simulations, we demonstrate that the translocation time can be described by a simple scaling law that exhibits a nonlinear dependence on the degree of polymerization and that is sensitive to the nature of the confining geometry. These results contradict earlier predictions but are in agreement with recently confirmed geometry-dependent expressions for the free energy of confinement.

Computer Simulation↗

PubMed2006

Self-avoiding flexible polymers under spherical confinement.

We compute the free energy of confinement for a flexible self-avoiding polymer inside a spherical cavity. Accurate numerical results allow us to arbitrate between three competing scaling predictions. For moderate confinement, the free energy exhibits a power-law dependence on cavity size that is different from what is observed for planar and cylindrical confinement. At high monomer concentrations, crossover to a different scaling regime is observed, consistent with the screening of the excluded-volume interactions. We demonstrate how our findings lead to a revised prediction for the escape time of a polymer from a spherical confinement.

Models, Molecular↗

PubMed2006

Clusters of charged Janus spheres.

We study the assembly of spherical particles with opposite electric charge on both hemispheres, in the case that the particle diameter exceeds the electrostatic screening length. Clusters result, not strings. The cluster shapes are analyzed by combined epifluorescence microscopy and Monte Carlo computer simulations with excellent agreement, indicating that the particles assemble in aqueous suspension to form equilibrated aggregates. The simulations show that charge asymmetry of individual Janus particles is preserved in the clusters.

Colloids↗

PubMed2005

Force barriers for membrane tube formation.

We used optical tweezers to measure the force-extension curve for the formation of tubes from giant vesicles. We show that a significant force barrier exists for the formation of tubes, which increases linearly with the radius of the area on which the pulling force is exerted. The tubes form through a first-order transition with accompanying hysteresis. We confirm these results with Monte Carlo simulations and theoretical calculations. Whether membrane tubes can be formed in, for example, biological cells, thus depends on the details of how forces are applied.

Biotin↗

PubMed2002

Formation of vortex loops (strings) in continuous phase transitions.

The formation of vortex loops (global cosmic strings) in an O(2) linear sigma model in three spatial dimensions is analyzed numerically. For over-damped Langevin dynamics we find that defect production is suppressed by an interaction between correlated domains that reduces the effective spatial variation of the phase of the order field. The degree of suppression is sensitive to the quench rate. A detailed description of the numerical methods used to analyze the model is also reported.

Journal Article↗