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A new method for the processing of textured YBa 2 Cu 3 O y (Y123) thick film stripes on metallic tapes is discussed. The process involves the texturing of Y123 grains by a localized directional solidification method by creating constitutional gradients along the width of the precursor Y 2 BaCuO 5 (Y211) stripe during an infiltration and growth process. The differences in the solidification temperatures of different rare earth 123 compounds were utilized to generate the constitutional gradients. The sample configuration involves printed lines of light (Nd) and heavy (Yb) rare earth compounds on either side of an airbrushed Y211 stripe underneath a liquid phase (barium cuprates) layer. The higher peritectic temperature (T p ) Nd regions serve as nucleating sites for Y123 grains nucleated in the adjacent Y211 stripes and the constitutional gradients produced due to the diffusion of respective rare earth ions between the Nd and Yb regions, typically of 200 K cm −1 in the region, induce a driving force for the directional growth of the nucleated grains. The solidification is analogous to that in a typical Bridgman furnace in applied high temperature gradients. The process, being independent of growth rate parameter and texture of the underlying substrate, is suitable for the fabrication of long length thick film conductors by a wind and react process in simple box type furnaces.

Therapeutic use of ultrasound (US) has a great potential for minimally invasive therapy. We have studied acoustic microbubble delivery for effective sonoporation and thermal therapy. To apply the techniques in vivo, a navigation system for US field positioning is indispensable. To address this issue, we have developed an intuitive navigation system using augmented reality (AR) technology. The system consists of an optical tracking device, a linear US probe, a focused US field source (US transducer) with 2.0-mm focal spot, a USB video camera, and navigation software. The probe was calibrated accurately using US probe calibration technique. Also, the transducer was calibrated using a three-dimensional sound field measurement device. Finally, the camera was calibrated using a chess board. The system we developed provides two kinds of augmented information : 1) therapeutic US field visualization on echogram, and 2) echogram plane and sound field visualization on video frame. In this study, the respective calibration accuracies were validated and microbubble trapping experiments using the focused US transducer and artificial blood vessel with 2.0-mm diameter were conducted. In the experiments, microbubbles were trapped inside the artificial blood vessel using the navigation system, implying that the focus position could be located in the blood vessel. The results demonstrated that the system we developed has adequate accuracy for microbubble control in 2.0-mm blood vessels.

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