Yuki Noguchi

This letter presents an acoustic metasurface that converts longitudinal acoustic waves into transverse elastic waves in an acoustic-elastic coupled system. Metasurface configurations are obtained by a level set-based topology optimization method, and we describe the mechanism that changes the direction of the wave motion. Numerical examples of 2D problems with prescribed frequencies of incident acoustic waves are provided, and transverse elastic wave amplitudes are maximized by manipulating the

We present a topology optimization method for the design of labyrinthine metamaterials with a large path length for acoustic wave propagation. An objective function maximizes the pressure gradient in an air-filled region at a low frequency, and a level set-based optimization method enables the optimal design of the labyrinthine structure with high computational efficiency owing to the concept of topological derivative. First, we explain the design settings of labyrinthine metamaterials. Next, th

Summary This paper presents a level set–based topology optimization method for the design of an acoustic metamaterial with negative bulk modulus in an acoustic‐elastic coupled system. To represent the coupled system, we propose a two‐phase material model in which the solid and acoustic phases are mixed. This model allows the coupled system to be represented uniformly and avoids the need to impose the coupling conditions typically required in analyses of acoustic‐elastic coupled systems. The effe

The pharmacokinetics (PK) of an antibody in the brain and the spinal cord is insufficiently understood, which is an obstacle to the discovery of antibody drugs that target diseases in the central nervous system. In this study, we focused on the elimination of IgG from cerebrospinal fluid (CSF) circulating in the brain and the spinal cord in rats, and, to evaluate the influence of CSF bulk flow on the clearance of IgG, also examined the PK of inulin in CSF. To monitor their concentrations in CSF,

Continuous tuning of the backbone conformation and interchain distance of a π-conjugated polymer is an essential prerequisite to unveil the inherent electrical and optical features of organic electronics. To this end, applying pressure in a hydrostatic medium or diamond anvil cell is a facile approach without the need for side-chain synthetic engineering. We report the development of high-pressure, time-resolved microwave conductivity (HP-TRMC) and evaluation of transient photoconductivity in th

Herein, a structural design for labyrinthine acoustic metamaterial is proposed using a topology optimization method to realize a subwavelength bandgap preventing the transmission of low‐frequency sounds. The optimized design is composed of air‐filled channels of different widths, which exhibit the subwavelength bandgap based on the monopole resonance induced in the meta‐atom. In addition to the optimized meta‐atom design, a simplified meta‐atom design with a small coiling coefficient is proposed

Cancer immunotherapies are powerful therapeutic options for cancer patients. To enhance the therapeutic effects of cancer immunotherapies, we plan to develop novel immunostimulatory drugs for use in combination with cancer immunotherapy. In the present study, we focused on tetracyclines, the effects of which are controversial for immunotherapy. We examined the effects of tetracyclines on human T cells in the peripheral blood of healthy donors and the tumor tissues of non-small cell lung cancer (

This letter presents an explicit formulation for the topological derivative of a two-dimensional acoustic-elastic coupled system, expressed with a two-phase material model based on Biot's theory. First, we briefly explain the two-phase material model in which the objective functional is assumed to be a domain integral of a certain function of velocity potential. The shape derivative of the objective functional is obtained using the usual Lagrangian formulation and we then construct the adjoint e