We propose a new class of acoustic waveguides with tunable bandgaps (TBs) by using vibroacoustic metamaterials with shunted periodic piezoelectric unit cells. The unit metamaterial cells that consist of a single crystal piezoelectric transducer and an electrical shunt circuit are designed to induce a strong vibro-acousto-electrical coupling, resulting in a tunable acoustic bandgap as well as local structural resonance and Bragg scattering bandgaps. The present results show that the TB frequency can be actively controlled and the transmission loss of the acoustic wave can be greatly improved by simply changing the inductance values in the shunt circuit.
Cardiac calcification usually occurs in patients with end-stage renal disease. However, rapid progression of cardiac calcification is rarely associated with secondary hyperparathyroidism of end-stage renal disease. We report a patient with end-stage renal disease who showed moderate left ventricular hypertrophy at the first echocardiography, and showed severe myocardial calcification and severe mitral valve stenosis 4 years later. We suspected a rapid progression 'porcelain heart' cardiomyopathy secondary to hyperparathyroidism of end-stage renal disease. The patient underwent parathyroidectomy, and considered mitral valve replacement.
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