PubMed · 4436778
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
J F Bavitz, N R Bohidar, J I Karr, F A Restaino. 1974. Letter: Tablet strength testing.. https://doi.org/10.1002/jps.2600631003
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Microhardnesses of five types of renal calculi: calcium apatite (82.5%)/magnesium ammonium phosphate hydrogen (10%)/calcium oxalate monohydrate (7.5%); calcium apatite (95%)/calcium oxalate monohydrate (5%); magnesium ammonium phosphate hydrogen (90%)/calcium apatite (10%); calcium oxalate monohydrate (85%)/calcium apatite (15%); and cystine (100%) were measured. Using Knoop and Vickers indenters the effects of chemical composition and microstructure on the microhardness measurement were assessed. Calcium oxalate monohydrate, magnesium ammonium phosphate hydrogen, and cystine stones, without apparent structure pattern, showed neither regional nor directional differences in their microhardness. In contrast, calcium apatite stones, with distinctly concentric laminae structure, showed regional variations which were correlated with the chemical composition of stone constituents. Scanning electron microscopy of the indenter impressions were taken to help in interpreting the directional dependence in Knoop hardness measurements with respect to the microstructure of the calculi. Vickers measurements showed the crystalline stones were isotropic within a layer. Combined results of Knoop and Vickers measurements indicate that the anisotropic Knoop hardness readings seen in the laminated regions were structural but not material-based. Implications of the results for the fragmentation of renal calculi in extracorporeal shock wave lithotripsy are discussed.
Ultrasonic properties of kidney stones were studied with a double-probe-through-transmission technique, the micro hardness was studied using the Viker indentation method and the chemical composition studied using an X-ray technique. The microhardness is found to vary with chemical composition as well as ultrasonic propagation velocity. The comparative results obtained are discussed in detail.
Explore the source record for details and available documents.