On the precision and accuracy of the acoustic birefringence technique for stress evaluation

This paper presents a numerical procedure for estimation of the precision and accuracy of the acoustic birefringence technique as used in the Instituto de Engenharia Nuclear (IEN) for evaluation of residual and applied stresses in structures and components, mainly of the nuclear power industry. This procedure shall be incorporated to the signal processing module of the ultrasonic system used at IEN’s Ultrasonic Laboratory to account in an automatic and systematic way for the uncertainties in the input data and their propagation throughout the calculations. The acoustic birefringence is generally defined from the speeds of two mutually orthogonal volumetric waves of normal incidence, but when the use of a pulse-echo measurement system is feasible, the birefringence can be defined directly from the time-of-flight of the waves, since they travel the same physical space. The times-of-flight of the waves can thus be regarded as the primary variables of interest. They are estimated by coupling the mathematical techniques of cross correlation and data interpolation, whereas the material’s acoustoelastic constant is determined via a weighted linear regression. An Excel spreadsheet performs all calculations taking into account the uncertainties and the number of significant digits in the results. As an example of the procedure developed, the estimation of the precision and accuracy in the evaluation of the stresses acting in a beam under bending is presented. The analytical solution derived from the strength of materials theory was used as the reference value for accuracy estimation purpos

The effect of an extract from Ganoderma lucidum (reishi) on the labeling of blood constituents with technetium-99m and on the survival of Escherichia coli

This study evaluated effects of an aqueous extract of Ganoderma lucidum (reishi) on the labeling of blood constituents with technetium-99m (99mTc) and on the survival of cultures of Escherichia coli treated with stannous chloride. Blood samples from Wistar rats were treated with reishi extract, radiolabeling procedure was performed, plasma (P), blood cells (BC) and insoluble (IF) and soluble (SF) fractions of P and BC were separated. The radioactivity was counted for the determination of the percentages of radioactivity (%ATI). Cultures of Escherichia coli AB1157 were treated with stannous chloride in the presence and absence of reishi extract. Blood samples and bacterial cultures treated with NaCl 0.9% were used as controls. Data indicated that reishi extract altered significantly (p99mTc and protecting bacterial cultures against oxidative damage induced by stannous chloride