Gating in channels and nanopores plays a key role in regulating flow of ions across membranes. Molecular simulations provide a 'computational microscope' which enables us to examine the physical nature of gating mechanisms at the level of the single channel molecule. Water enclosed within the confines of a nanoscale pore may exhibit unexpected behaviour. In particular, if the molecular surfaces...

Experimental measurements of the thermal expansion coefficient (alpha), permeability (k), and diffusivity (D) of water and 1 M solutions of NaCl and CaCl(2) are interpreted with the aid of molecular dynamics (MD) simulations of water in a 3 nm gap between glass plates. MD shows that there is a layer approximately 6 A thick near the glass surface that has alpha approximately 2.3 times higher and...

In natural waters, the equilibrium state of hydrophobic organic compounds among bottom sediment (BS), suspended sediment (SPS), and water is fundamental to infer their transfer flux and aqueous bioavailability. However, this type of information remains scarce and fragmented. This study systematically evaluated the equilibrium state of polycyclic aromatic hydrocarbons (PAHs) in the Yangtze River...

The critical Rayleigh number for convective flow of pore water through a permeable spherical body is derived. The result affords constraints on carbonaceous chondrite planetesimal sizes and rates of heat production. If the chemical compositions of carbonaceous chondrites are taken as evidence against flow of pore water, then the present calculations suggest that the parent bodies were less than...

Abstract The porous nature of amorphous solid water (ASW) can significantly effect the chemical evolution any planetary or astrophysical surface it forms on due to its ability trap and retain volatiles. amount volatiles that enter an ASW grain mantle is limited by how interconnected pores are each other exterior surface. Previous laboratory studies examined interconnectivity in thin films relev...

(See related article by A. Parikova et al. Free water transport, small pore transport and the osmotic pressure gradient. Free water transport, small pore transport and the osmotic pressure gradient three-pore model of peritoneal transport. Simonsen O et al. Fluid and electrolyte transport across the peritoneal membrane during CAPD according to the three-pore model. A et al. Aquaporin-1 plays an...

Phosphorus (P) retention is an important ecosystem service provided by sediments and soils. However, when shallow aquatic sediments and poorly drained soils dry and re-flood, they can be a source, rather than a sink, of P. Using experimental drying and re-flooding in the laboratory, we assessed the resultant sediment–water P exchange in a biogeochemically diverse set of sediments from 16 sites ...