Electrokinetics of Glass Surfaces. I. Charge Densities at the Solid/Gas and the Solid/Liquid Interfaces of Porous Glasses

An attempt is described to determine the charge densities at different layers of the surfaces of glass. Three different techniques were used: the heat-of-immersion technique, the electron spin resonance hyperfine splitting measurements, and the electrokinetic streaming potential or current technique. Estimates of the charge densities at the various interfaces show the structure can be subdivided into the high and low charge portions. The heat-of-immersion technique, looks into the actual solid surface: there the charge density is estimated at in excess of 1014 unit e-charges per cm2• The hyperfine splitting of the 107Ag ESR spectrum assumed due to the electrostatic field at the site of the localized atom position: a charge density of 0.7 to l.3Xl013 is estimated. It is assumed that the Ag atom is localized in the gel-like layer- solution interface. The excess counter-ion charge in the diffuse part of the double layer in the liquid phase is estimated at 3 to 7 X 1012• Thus, the high charge density plane is the interface solid-gel layer. The estimates are based on independent models of the interface structure, widely accepted in literature, although not entirely free of arbitrary assumptions

Sellar angiolipomas: two case reports and a review of the literature

Angiolipomas are mesenchymal hamartomas composed of abnormal blood vessels and mature adipose tissue, most commonly found in the subcutaneous tissue of the extremities. Intracranial location is extremely rare, and only five cases have been described in the sellar region. We report on two patients that were initially diagnosed with pituitary adenomas that were postoperatively verified as angiolipomas. Sellar angiolipomas should be considered in the differential diagnosis of pituitary lesions due to the potential catastrophic bleeding during surgery. Preoperative diagnosis is very difficult; however, some MRI characteristics can help make an accurate diagnosis. Adequate MRI sequences should be used in the evaluation of pituitary lesions, as they can help optimize the microsurgical management