Scaling behaviour for the water transport in nanoconfined geometries

The transport of water in nanoconfined geometries is different from bulk phase and has tremendous implications in nanotechnology and biotechnology. Here molecular dynamics is used to compute the self-diffusion coefficient D of water within nanopores, around nanoparticles, carbon nanotubes and proteins. For almost 60 different cases, D is found to scale linearly with the sole parameter theta as D(theta)=DB[1+(DC/DB-1)theta], with DB and DC the bulk and totally confined diffusion of water, respectively. The parameter theta is primarily influenced by geometry and represents the ratio between the confined and total water volumes. The D(theta) relationship is interpreted within the thermodynamics of supercooled water. As an example, such relationship is shown to accurately predict the relaxometric response of contrast agents for magnetic resonance imaging. The D(theta) relationship can help in interpreting the transport of water molecules under nanoconfined conditions and tailoring nanostructures with precise modulation of water mobility

Cerebrospinal Fluid Leaks of Temporal Bone Origin: Selection of Surgical Approach

Cerebrospinal fluid leaks of the temporal bone are rare, often occult, and sometimes challenging to localize and repair. This is a retrospective study of eight patients with spontaneous cerebrospinal fluid leak and six patients with cerebrospinal fluid leak or encephalocele discovered during chronic ear surgery who were treated in a tertiary medical center over a 5-year period. All received preoperative temporal bone computed tomography, and six also underwent magnetic resonance imaging, one computed tomography cisternography, and one radionuclide cisternography. All patients initially underwent a transmastoid surgical approach. Additional exposure was necessary in three patients; two underwent middle fossa craniotomy and another required minicraniotomy. Primary surgical repair was successful in six of the eight patients with spontaneous leaks and in all six chronic ear patients. Both recurrences required intradural middle fossa repair. An individualized approach should be taken for repair of temporal bone cerebrospinal fluid leaks. In this series, most were successfully repaired in a single stage using a transmastoid or combined approach. The transmastoid approach provides information about the precise size and location of the dural defect. A primary transcranial approach is needed for defects that are multiple, located in the petrous apex, and in revision cases