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A hybrid method for estimating temperature with spatial mapping using diagnostic ultrasound, based on detection of echo shifts from tissue undergoing thermal treatment, is proposed. Cross-correlation and zero-crossing tracking are two conventional algorithms used for detecting echo shifts, but their practical applications are limited. The proposed hybrid method combines the advantages of both algorithms with improved accuracy in temperature estimation. In vitro experiments were performed on porcine muscle for preliminary validation and temperature calibration. In addition, thermal mapping of rabbit thigh muscle in vivo during high-intensity focused ultrasound heating was conducted. Results from the in vitro experiments indicated that the difference between the estimated temperature change by the proposed hybrid method and the actual temperature change measured by the thermocouple was generally less than 1 °C when the increase in temperature due to heating was less than 10 °C. For the in vivo study, the area predicted to experience the highest temperature coincided well with the focal point of the high-intensity focused ultrasound transducer. The computational efficiency of the hybrid algorithm was similar to that of the fast cross-correlation algorithm, but with an improved accuracy. The proposed hybrid method could provide an alternative means for non-invasive monitoring of limited temperature changes during hyperthermia therapy.

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Atomistic simulations of nanoindentations with spherical and Berkovich indenters were carried out to study the effects of size on nanohardness. For spherical indenters with the radii ranging from 10 Å to 50 Å, it was found that nanohardness was inversely proportional to the indenter radius. For Berkovich indenters, it was found that nanohardness roughly followed a trend that was inversely proportional to the indentation depth. It was concluded that the indentation size effect at the atomistic scale might follow a trend similar to that observed at the micron and sub-micron scales. Biographical notes: Chih-Yang Chan is a graduate student working toward his Master degree in the Department of Civil Engineering, National Taiwan University. His research interest is atomistic modelling of nanoindentation phenomena.Yen-Yu Chen is a PhD candidate in the Department of Civil Engineering, National Taiwan University. His research interests are to develop large-scale atomistic and multiscale modelling software program and to develop novel finite temperature and dynamic quasicontinuum method. Shu-Wei Chang was a former graduate student of the Department of Civil Engineering, National Taiwan University. He is now in the Department of Civil and Environmental Engineering, Massachusetts Institute of Technology working toward his PhD degree. His research interests cover mathematical analysis of multiscale methods and multiscale modelling of materials and biological phenomena.Chuin-Shan Chen received his PhD degree from Cornell University and worked as a research associate at the Cornell Theory Center before he joined National Taiwan University. His research interests include molecule-enabling mechanics, multiscale modelling, multiphysics modelling, materials modelling, Atomistic studies of nanohardness size effects 63 microcantilever and nanowire biosensors, ultrasound sensors and actuators, solid fluid interaction, computational mechanics, finite element method, discrete element method, coarse-grained molecular dynamics, large-scale software development. He has a distinguished research record on multiscale mechanics and materials modelling and is the