Imaging the sublimation dynamics of colloidal crystallites.

We studied the kinetics of sublimating crystals with single-particle resolution by experiments with colloidal spheres and by computer simulations. A short-range attraction between spheres led to crystallites one to three layers thick. The spheres were tracked with optical microscopy while the attraction was reduced and the crystals sublimated. Large crystallites sublimated by escape of particles from the perimeter. The rate of shrinkage was greatly enhanced, however, when the size decreased to less than 20 to 50 particles, depending on the location in the phase diagram. At this size, the crystallites transformed into a dense amorphous structure, which rapidly vaporized. The enhancement of kinetics by metastable or unstable phases may play a major role in the melting, freezing, and annealing of crystals.

Pigmented villonodular synovitis presenting as a large lateral knee mass. Case report and review of the literature.

Pigmented villonodular synovitis is characterized by synovial villonodular lesions with hemosiderin pigmentation and a stromal infiltrate of histiocytes. Analogous lesions may occur in joints, bursae, and tendon sheaths. Although the etiology and natural history of pigmented villonodular synovitis remain unknown, it should be considered a benign entity. It usually presents as either diffuse monoarticular involvement with chronic pain and swelling, or a more localized nodular lesion, typically involving the fingers or knees. Although treatment involves excision of the involved tissue, due to its benign behavior, radical surgical procedures are not indicated. A case report of a large, extra-articular mass is described, with histologic and clinical changes consistent with localized PVS.

Non calculous cholecystitis: an 8 year review of cases treated by elective cholecystectomy.

From a total of 248 cases of cholecystectomy, 36 were found to be without stones. These cases of acalculous cholecystitis have been reviewed with regard to signs, symptoms and radiological investigations. The complications of operative treatment have been documented and the etiology of the condition discussed. As a result of favourable outcome of operative treatment in these patients, it is suggested that surgery should be considered even in the absence of positive radiological findings at an earlier date.