Synthetically non-Hermitian nonlinear wave-like behavior in a topological mechanical metamaterial.

Topological mechanical metamaterials have enabled new ways to control stress and deformation propagation. Exemplified by Maxwell lattices, they have been studied extensively using a linearized formalism. Herein, we study a two-dimensional topological Maxwell lattice by exploring its large deformation quasi-static response using geometric numerical simulations and experiments. We observe spatial nonlinear wave-like phenomena such as harmonic generation, localized domain switching, amplification-enhanced frequency conversion, and solitary waves. We further map our linearized, homogenized system to a non-Hermitian, nonreciprocal, one-dimensional wave equation, revealing an equivalence between the deformation fields of two-dimensional topological Maxwell lattices and nonlinear dynamical phenomena in one-dimensional active systems. Our study opens a regime for topological mechanical metamaterials and expands their application potential in areas including adaptive and smart materials and mechanical logic, wherein concepts from nonlinear dynamics may be used to create intricate, tailored spatial deformation and stress fields greatly transcending conventional elasticity.

Topological transformability and reprogrammability of multistable mechanical metamaterials.

Concepts from quantum topological states of matter have been extensively utilized in the past decade to create mechanical metamaterials with topologically protected features, such as one-way edge states and topologically polarized elasticity. Maxwell lattices represent a class of topological mechanical metamaterials that exhibit distinct robust mechanical properties at edges/interfaces when they are topologically polarized. Realizing topological phase transitions in these materials would enable on-and-off switching of these edge states, opening opportunities to program mechanical response and wave propagation. However, such transitions are extremely challenging to experimentally control in Maxwell topological metamaterials due to mechanical and geometric constraints. Here we create a Maxwell lattice with bistable units to implement synchronized transitions between topological states and demonstrate dramatically different stiffnesses as the lattice transforms between topological phases both theoretically and experimentally. By combining multistability with topological phase transitions, this metamaterial not only exhibits topologically protected mechanical properties that swiftly and reversibly change, but also offers a rich design space for innovating mechanical computing architectures and reprogrammable neuromorphic metamaterials. Moreover, we design and fabricate a topological Maxwell lattice using multimaterial 3D printing and demonstrate the potential for miniaturization via additive manufacturing. These design principles are applicable to transformable topological metamaterials for a variety of tasks such as switchable energy absorption, impact mitigation, wave tailoring, neuromorphic metamaterials, and controlled morphing systems.

Generation, Transmission, and Regulation of Mechanical Forces in Embryonic Morphogenesis.

Embryonic morphogenesis is a biological process which depicts shape forming of tissues and organs during development. Unveiling the roles of mechanical forces generated, transmitted, and regulated in cells and tissues through these processes is key to understanding the biophysical mechanisms governing morphogenesis. To this end, it is imperative to measure, simulate, and predict the regulation and control of these mechanical forces during morphogenesis. This article aims to provide a comprehensive review of the recent advances on mechanical properties of cells and tissues, generation of mechanical forces in cells and tissues, the transmission processes of these generated forces during cells and tissues, the tools and methods used to measure and predict these mechanical forces in vivo, in vitro, or in silico, and to better understand the corresponding regulation and control of generated forces. Understanding the biomechanics and mechanobiology of morphogenesis will not only shed light on the fundamental physical mechanisms underlying these concerted biological processes during normal development, but also uncover new information that will benefit biomedical research in preventing and treating congenital defects or tissue engineering and regeneration.

Effect of cinnamon on starch hydrolysis of rice pudding: Comparing static and dynamic in vitro digestion models.

Two in vitro digestion methods (static and dynamic) were applied in this study to investigate the effect of cinnamon on starch hydrolysis of rice pudding during in vitro digestion. The dynamic model simulated the major physiological processes including gastric emptying, motility, gastric acidification, and digestive secretions. The INFOGEST static method, which is widely adopted in digestion simulation studies, was conducted as a comparison. Two meals (i.e., rice pudding with and without cinnamon) were digested in the oral, gastric, and small intestinal phases in both models. Higher starch hydrolysis was observed in the gastric and intestinal phases in the dynamic model compared to the static model (p < 0.05). Furthermore, a significant inhibitory effect of cinnamon on starch hydrolysis was exclusively observed in the dynamic model . The difference could be attributed to the distinct gastric conditions including pH profiles, gastric emptying, and gastrointestinal motility in the two models. Our results indicated that the dynamic model could more closely estimate the effect of cinnamon on starch hydrolysis during digestion by simulating physiologically important gastrointestinal conditions in humans. Our findings also contribute to the growing body of scientific data suggesting that cinnamon may benefit hyperglycemic management due to its inhibitory effects on digestion enzymes.