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Biomedical subjects

S Leibler

Publications and source records attributed to S Leibler.

49 records · Page 3Linked to original sources
PubMed1990

Simulation of shape changes and adhesion phenomena in an elastic model of erythrocytes.

We present simulations of a model of a closed membrane that shares important features with erythrocytes: resistance to bending and shear, membrane asymmetry, and an osmotic pressure difference between the interior and exterior. By varying a few parameters we obtain several realistic (e.g., biconcave and cup-like) shapes whose fluctuations, analogous to flickering of erythrocytes, and mutual transformations are studied in thermal equilibrium. Our simulations form a basis for quantitative analysis of recent experiments done on erythrocytes and artificial bilayer vesicles. They also predict effects that could be observed in experiments such as an "'unbinding" phenomenon, i.e., a separation of adhering cells induced by thermal fluctuations.

Animals↗
PubMed1988

Geometrical aspects of the frustration in the cubic phases of lyotropic liquid crystals.

Bicontinuous cubic phases, composed of bilayers arranged in the geometries of periodic minimal surfaces, are found in a variety of different lipid/water systems. It has been suggested recently that these cubic structures arrive as the result of competition between two free-energy terms: the curvature energy of each monolayer and the stretching energy of the lipid chains. This scenario, closely analogous to the one that explains the origin of the hexagonal phases, is investigated here by means of simple geometrical calculations. It is first assumed that the lipid bilayer is of constant thickness and the distribution of the (local) mean curvature of the phospholipid-water interfaces is calculated. Then, assuming the mean curvature of these interfaces is constant, the distribution of the bilayer's thickness is calculated. Both calculations quantify the fact that the two energy terms are frustrated and cannot be satisfied simultaneously. However, the amount of the frustration can be smaller for the cubic phase than for the lamellar and hexagonal structures. Therefore, this phase can appear in the phase diagram between the other two, as observed in many recent experiments.

Crystallization↗