Microhardness and acoustic behavior of calcium oxalate monohydrate urinary stone

Renal stone containing calcium oxalate monohydrate as a major component was subjected to microhardness and acoustic studies in order to understand its mechanical properties in vitro and use them to help in the treatment procedures for more effective stone fragmentation. The chemical composition and the crystalline nature of the stone were verified using Fourier Transform Infrared spectroscopy, X-ray diffraction and the stone was also analyzed using thermo gravimetric analysis and by differential thermal analysis. The microhardness values were almost constant around 1000 MNm(-2) in the load range of 1.96 N-9.8 N. The values of fracture toughness and brittleness index for the stone in this load range was varying from 1.12 (0.307) MNm(-3/2) to 1.48 (0.296) MNm(-3/2) and 674.25 m(-1/2) to 878.07 m(-1/2) respectively. The density of the stone and the ultrasonic longitudinal wave velocity in the stone were found to be 1880 kgm(-3) and 3399 ms(-1) respectively indicating that the urinary stone under study was a compact one. The acoustic impedance and the dynamic modulus values were calculated as 6.39 x 10(6) kgm(-2) s(-1) and 21.72 GNm(-2) respectively. (C) 2007 Elsevier B.V. All rights reserved.