Acoustic Metamaterials Group (China)

Spatially exponential distributions of material properties are ubiquitous in many natural and engineered systems, from the vertical distribution of the atmosphere to acoustic horns and anti-reflective coatings. These media seamlessly interface different impedances, enhancing wave transmission and reducing internal reflections. This work advances traditional transfer matrix theory by integrating analytical solutions for acoustic exponential materials, which possess exponential density and/or bulk modulus, offering a more accurate predictive tool and revealing the physical mechanism of broadband anti-reflection for sound propagation in such non-uniform materials. Leveraging this method, we designed an acoustic dipole array that effectively mimics exponential mass distribution. Through experiments with precisely engineered micro-perforated plates, we demonstrate an ultra-low reflection rate of about 0.86% across a wide frequency range from 420 Hz to 10,000 Hz. Our modified transfer matrix approach underpins the design of exponential materials, and our layering strategy for stacking acoustic dipoles suggests a pathway to more functional gradient acoustic metamaterials.

This post hoc analysis of the placebo-controlled phase 3 FRAME study assessed the efficacy and safety of romosozumab in a subpopulation of Japanese postmenopausal women with osteoporosis and chronic kidney disease (CKD). Data were analyzed by baseline estimated glomerular filtration rate (eGFR), where < 90mL/min/1.73 m2 denoted CKD and ≥ 90mL/min/1.73 m2 indicated normal renal function. Efficacy outcomes included percent change in lumbar spine, total hip, and femoral neck bone mineral density (BMD) at 12months from baseline (primary) and incidence of new vertebral and non-vertebral fractures. Tolerability was also assessed. Of 489 Japanese patients with available eGFR data, 339 had mild-to-moderate CKD (romosozumab, n = 170; placebo, n = 169) and 150 had normal renal function (romosozumab, n = 75; placebo, n = 75). Compared with placebo, romosozumab increased lumbar spine BMD by 14.8% (95% confidence interval [CI] 13.7-15.9) and 15.2% (95% CI 13.4-16.9) in the eGFR < 90 and ≥ 90mL/min/1.73 m2 subgroups, total hip BMD by 4.6% (95% CI 3.8-5.4) and 5.5% (95% CI 4.4-6.7), and femoral neck BMD by 4.0% (95% CI 2.9-5.2) and 5.5% (95% CI 3.8-7.1) at 12months, respectively (all p < 0.001 vs. placebo). New vertebral fracture incidence was numerically lower with romosozumab than placebo at 12months in both eGFR subgroups, while the incidence of adverse events was similar between subgroups. Romosozumab for 12months is an effective and well-tolerated treatment option for Japanese patients with osteoporosis and mild-to-moderate CKD.