Multi-functional programmable active acoustic meta-device: acoustic switch, lens, and barrier.

Active acoustic metamaterials (AAMM) have garnered special attention because of their potential as multi-function devices. In this direction, the present article demonstrates a novel AAMM that can be programmed as a multi-functional Active Acoustic Meta-device (AAMD) that can switch functionalities between Acoustic Switch (AS), Acoustic Lens (AL), and Acoustic Barrier (AB). Functionality: AL corresponds to the wave vector space, and AS and AB correspond to the frequency space of the proposed AAMM.

Metamaterial foundation for seismic wave attenuation for low and wide frequency band.

Metamaterials are periodic structures made by repeating a unit cell. Such a structure shows frequency-specific wave attenuation behaviour. In this work, a 2D metamaterial foundation is proposed for the seismic protection of buildings.

Fracture Mechanism and Fracture Toughness at the Interface Between Cortical and Cancellous Bone.

The microstructure at the interface of cortical and cancellous bone is quite complicated. The fracture mechanisms at this location are necessary for understanding the comprehensive fracture of the whole bone. The goal of this study is to identify fracture toughness in terms of J integral and fracture mechanism at the interface between cortical and cancellous bone.

Experimental and numerical comparisons between finite element method, element-free Galerkin method, and extended finite element method predicted stress intensity factor and energy release rate of cortical bone considering anisotropic bone modelling.

Stress intensity factor and energy release rate are important parameters to understand the fracture behaviour of bone. The objective of this study is to predict stress intensity factor and energy release rate using finite element method, element-free Galerkin method, and extended finite element method and compare these results with the experimentally determined values. For experimental purpose, 20 longitudinally and transversely fractured single-edge notched bend specimens were prepared and tested according to ASTM standard.

Enhancing the sound transmission loss through acoustic double panel using sonic crystal and porous material.

Acoustic panels are widely used for sound insulation in various applications. Sound transmission loss (STL) through the panel is due to a change in acoustic impedance as sound travels from one medium to another. In double panels, STL further increases due to multiple reflections in air cavity.

Erdheim-Chester disease: a unique presentation with liver involvement and vertebral osteolytic lesions.

Erdheim-Chester disease is a very rare xanthogranulomatous, non-Langerhans cell systemic histiocytosis with an unknown etiology and pathogenesis. Histologically, it is characterized by a diffuse infiltration with large, foamy histiocytes, rare Touton-like giant cells, lymphocytic aggregates, and fibrosis. The histiocytes differ from the Langerhans cell group in ontogenesis, immunohistochemistry (positive for CD68 and negative for CD1a and S100 protein), and ultrastructural appearance (lack of Birbeck granules).