Studies on water transport in quasi two-dimensional porous systems using neutron radiography

The spontaneous wetting and drying of flat porous samples of linen, cotton and synthetic textiles were studied using dynamic neutron radiography (DNR). The progress of the wetting process of the media was delineated from the obtained neutron dynamical radiography images. The results of the investigation reveal a non-classical behaviour of kinetics of wicking of these materials. The character of the wetting kinetics is discussed in terms of the fractal character of the tortuosity of fabric capillaries.

Atomistic basis of opening and conduction in mammalian inward rectifier potassium (Kir2.2) channels

Potassium ion conduction through open potassium channels is essential to control of membrane potentials in all cells. To elucidate the open conformation and hence the mechanism of K+ ion conduction in the classic inward rectifier Kir2.2, we introduced a negative charge (G178D) at the crossing point of the inner helix bundle, the location of ligand-dependent gating. This “forced open” mutation generated channels that were active even in the complete absence of phosphatidylinositol-4,5-bisphosphate (PIP2), an otherwise essential ligand for Kir channel opening. Crystal structures were obtained at a resolution of 3.6 Å without PIP2 bound, or 2.8 Å in complex with PIP2. The latter revealed a slight widening at the helix bundle crossing (HBC) through backbone movement. MD simulations showed that subsequent spontaneous wetting of the pore through the HBC gate region allowed K+ ion movement across the HBC and conduction through the channel. Further simulations reveal atomistic details of the opening process and highlight the role of pore-lining acidic residues in K+ conduction through Kir2 channels.

Atomistic basis of opening and conduction in mammalian inward rectifier potassium (Kir2.2) channels

Potassium ion conduction through open potassium channels is essential to control of membrane potentials in all cells. To elucidate the open conformation and hence the mechanism of K+ ion conduction in the classical inward rectifier Kir2.2, we introduced a negative charge (G178D) at the crossing point of the inner helix bundle (HBC), the location of ligand-dependent gating. This ‘forced open’ mutation generated channels that were active even in the complete absence of phosphoinositol-4,5-bisphosphate (PIP2), an otherwise essential ligand for Kir channel opening. Crystal structures were obtained at a resolution of 3.6 Å without PIP2 bound, or 2.8 Å in complex with PIP2. The latter revealed a slight widening at the HBC, through backbone movement. Molecular dynamics (MD) simulations showed that subsequent spontaneous wetting of the pore through the HBC gate region allowed K+ ion movement across the HBC and conduction through the channel. Further simulations reveal atomistic details of the opening process and highlight the role of pore lining acidic residues in K+ conduction through Kir2 channels.

PHYSICO-CHEMICAL INTERACTIONS BETWEEN COMPONENTS OF THE Al/SiO2 SYSTEM IN METALLURGICAL SYNTHETIC PROCESSES OF CASTING PARTICULATE REINFORCED ALUMINUM ALLOYS

The physicochemical interactions between components in the Al/SiO2aluminum matrix compositions under various temperature conditions of processing are studied. The synthesis of aluminum oxide ceramics in aluminum melts for the production of particulate reinforced Al-Si/Al2O3alloys was performed. The addition of dispersed particles of silicon oxide ceramics was carried out by mixing into aluminum melt in a liquid-solid state. At the temperature-time processing of the Al/SiO2compositions, alumina ceramic with a contact surface layer providing spontaneous wetting with liquid aluminum is realized.