A magnetosome chain viewed as a bio-elastic magnet.

In light of the coarse-grained Monte Carlo numerical simulation method, the magnetosome chain stability of magnetotactic bacteria is analysed and discussed. This discrete chain of magnetic nanoparticles, encapsulated in a lipid membrane and flanked by filaments, orients bacteria in the geomagnetic field as a compass needle. Each magnetosome is a magnetite or greigite nanocrystal encapsulated in a soft lipid shell.

Self-organization of plants in a dryland ecosystem: Symmetry breaking and critical cluster size.

Periodical patterns of vegetation in an arid or semiarid ecosystem are described using statistical mechanics and Monte Carlo numerical simulation technique. Plants are characterized by the area that each individual occupies and a facilitation-competition pairwise interaction. Assuming that external resources (precipitation, solar radiation, nutrients, etc.

Geometrical and physicochemical considerations of the pit membrane in relation to air seeding: the pit membrane as a capillary valve.

A theoretical treatment of some of the factors influencing air seeding at the pit membranes of xylem vessels is given. Pit membrane structure, viewed as a three-dimensional mesh of intercrossing fibrils, and vulnerability to water-stress-induced air seeding are examined in the context of the Young-Laplace equation. Simple geometrical considerations of the porous membrane show that the vapor-liquid interface curvature radius is a function of fiber-fiber distance, fiber radius, wetting angle and position of the wetting line.

van der Waals equation of state for a fluid in a nanopore.

A generalization of the van der Waals equation of state is presented for a confined fluid in a nanopore. The pressure in the fluid, confined in a narrow pore of infinite length, has tensorial character. From this hypothesis, the Helmholtz free energy is constructed and expressions for the axial and transversal components of the pressure tensor are obtained.