ABSTRACT
Rheological behavior of silicate melts controls the dynamics of volcanic eruptions. Previous experimental studies have investigated melt viscosity and found non-Newtonian behavior of the melt under a high shear rate. However, the relationship between macroscopic rheology and atomic-scale behavior under shear remains unclear. We developed an experimental system for time-resolved x-ray diffraction (XRD) at high temperature to investigate the atomic-scale structural change in melts under shear. The manufactured deformation apparatus and heating furnace were set on the synchrotron radiation x-ray beamline (BL20XU) of SPring-8; the XRD pattern of the melt at high temperature could be observed using this system because the furnace mainly consists of a boron nitride cylinder with high x-ray transmittance. Here, we report results of fiber elongation experiments for a soda-lime melt. Melt fibers with â¼0.7 mm in diameter and â¼27 mm long were elongated at 100 µm sec-1 at temperatures of 595 °C and 620 °C, and the XRD pattern was obtained every 100 msec. Brittle failure of the melt occurred at 595 °C, whereas the melt viscously elongated at 620 °C. The XRD patterns obtained during elongation did not indicate any clear change immediately before brittle failure. The intensity of the XRD pattern decreased with the elongation at 620 °C, although there was no clear variation in its shape. These results indicate that the atomic-scale structure observed by XRD may not change during the elastic and viscous elongation of the soda-lime melt. This experimental system will be further developed and applied to more polymerized and natural silicate melts.
ABSTRACT
An otherwise healthy 85-year-old woman presented with purulent multifocal subcutaneous nodules on the dorsal side of the right forearm and hand. Histopathologic examination of the biopsied specimen showed a subcutaneous granuloma with central abscess and necrosis, consistent with phaeomycotic cyst. Faint brown septate hyphae and moniliform fungal elements were found in the granuloma. Culture of the discharge grew Phialophora verrucosa. This fungus has rarely been reported as a pathogen of subcutaneous phaeohyphomycosis. Subcutaneous phaeohyphomycosis usually presents as a single lesion. In this case of multifocal lesions, initial imperfect excision seems to have caused satellite lesions. To our knowledge, this is the first report of multifocal subcutaneous phaeohyphomycosis caused by P verrucosa. The disease responded to oral itraconazole administration.
