The ultra-slow reshaping of pine cones is dominated by the unique spring/square heterostructure in their vascular bundles, with the velocity slowed by sclereids. Inspired by this motion, a soft actuator showing unperceivable motion was developed.
Unperceivable motion mimicking hygroscopic geometric reshaping of pine conesThe hygroscopic deformation of pine cones, featured by opening and closing their scales depending on the environmental humidity, is a well-known stimuli-responsive model system for artificial actuators. However, it has not been noted that the deformation of pine cones is an ultra-slow process. Here, we reveal that vascular bundles with unique parallelly arranged spring/square microtubular heterostructures dominate the hygroscopic movement, characterized as ultra-slow motion with the outer sclereids. The spring microtubes give a much larger hygroscopic deformation than that of the square microtubes along the longitudinal axis direction, which bends the vascular bundles and consequently drives the scales to move. The outer sclereids with good water retention enable the vascular-bundle-triggered deformation to proceed ultra-slowly. Drawing inspiration, we developed soft actuators enabling controllable yet unperceivable motion. The motion velocity is almost two orders of magnitude lower than that of the same-class actuators reported, which made the as-developed soft actuators applicable in camouflage and reconnaissance.
Pine-cone-inspired actuators with spring/square (○/□) pillar couples enable unperceivable motion.
Feilong Zhang, Man Yang, Xuetao Xu, Xi Liu, Huan Liu, Lei Jiang & Shutao Wang
doi: 10.1038/s41563-022-01391-2 | |
| Cecilia Laschi & Barbara Mazzolai doi: 10.1038/s41563-022-01411-1 | |
An implantable tissue adhesive soft actuator adheres to muscle, generating mechanical stimulation, and activates mechanosensing pathways for prevention of atrophy in disuse muscles.
Active tissue adhesive activates mechanosensors and prevents muscle atrophyWhile mechanical stimulation is known to regulate a wide range of biological processes at the cellular and tissue levels, its medical use for tissue regeneration and rehabilitation has been limited by the availability of suitable devices. Here we present a mechanically active gel–elastomer–nitinol tissue adhesive (MAGENTA) that generates and delivers muscle-contraction-mimicking stimulation to a target tissue with programmed strength and frequency. MAGENTA consists of a shape memory alloy spring that enables actuation up to 40% strain, and an adhesive that efficiently transmits the actuation to the underlying tissue. MAGENTA activates mechanosensing pathways involving yes-associated protein and myocardin-related transcription factor A, and increases the rate of muscle protein synthesis. Disuse muscles treated with MAGENTA exhibit greater size and weight, and generate higher forces compared to untreated muscles, demonstrating the prevention of atrophy. MAGENTA thus has promising applications in the treatment of muscle atrophy and regenerative medicine.
MAGENTA provides mechanical stimulation to the target tissue.
Sungmin Nam, Bo Ri Seo, Alexander J. Najibi, Stephanie L. McNamara & David J. Mooney
doi: 10.1038/s41563-022-01396-x | |
A discovery-oriented synthesis and characterization platform uses interchangeable polymer components to explore a large and complex parameter space to find possible combinations of components that satisfy the design rules at multiple nanolithography patterns dimensions.
Optimized design of block copolymers with covarying properties for nanolithographyThe ability to impart multiple covarying properties into a single material represents a grand challenge in manufacturing. In the design of block copolymers (BCPs) for directed self-assembly and nanolithography, materials often balance orthogonal properties to meet constraints related to processing, structure and defectivity. Although iterative synthesis strategies deliver BCPs with attractive properties, identifying materials with all the required attributes has been difficult. Here we report a high-throughput synthesis and characterization platform for the discovery and optimization of BCPs with A-block-(B-random-C) architectures for lithographic patterning in semiconductor manufacturing. Starting from a parent BCP and using thiol–epoxy ‘click’ chemistry, we synthesize a library of BCPs that cover a large and complex parameter space. This allows us to readily identify feature-size-dependent BCP chemistries for 8–20-nm-pitch patterns. These blocks have similar surface energies for directed self-assembly, and control over the segregation strength to optimize the structure (favoured at higher segregation strengths) and defectivity (favoured at lower segregation strengths).
Design principle for creating a series of BCPs with tunable χN and Δγ = 0 using an A-b-(B-r-C) polymer architecture.
Hongbo Feng, Moshe Dolejsi, Ning Zhu, Soonmin Yim, Whitney Loo, Peiyuan Ma, Chun Zhou, Gordon S. W. Craig, Wen Chen, Lei Wan, Ricardo Ruiz, Juan J. de Pablo, Stuart J. Rowan & Paul F. Nealey
doi: 10.1038/s41563-022-01392-1 | |
Independently tailored nano- and mesoscale features are obtained in hierarchically assembled mixed graft block copolymers with precisely defined side-chain sequences.
Hierarchically engineered nanostructures from compositionally anisotropic molecular building blocksThe inability to synthesize hierarchical structures with independently tailored nanoscale and mesoscale features limits the discovery of next-generation multifunctional materials. Here we present a predictable molecular self-assembly strategy to craft nanostructured materials with a variety of phase-in-phase hierarchical morphologies. The compositionally anisotropic building blocks employed in the assembly process are formed by multicomponent graft block copolymers containing sequence-defined side chains. The judicious design of various structural parameters in the graft block copolymers enables broadly tunable compositions, morphologies and lattice parameters across the nanoscale and mesoscale in the assembled structures. Our strategy introduces advanced design principles for the efficient creation of complex hierarchical structures and provides a facile synthetic platform to access nanomaterials with multiple precisely integrated functionalities.
Hierarchical nanostructures constructed from GBCP-based CAMBBs.
Ruiqi Liang, Yazhen Xue, Xiaowei Fu, An N. Le, Qingliang Song, Yicheng Qiang, Qiong Xie, Ruiqi Dong, Zehao Sun, Chinedum O. Osuji, Jeremiah A. Johnson, Weihua Li & Mingjiang Zhong
doi: 10.1038/s41563-022-01393-0 | |
The authors use high-resolution angle-resolved photoemission spectroscopy to determine the microscopic structure of three-dimensional charge order in AV3Sb5 (A = K, Rb, Cs) and its interplay with superconductivity.
Charge order landscape and competition with superconductivity in kagome metalsIn the kagome metals AV3Sb5 (A = K, Rb, Cs), three-dimensional charge order is the primary instability that sets the stage for other collective orders to emerge, including unidirectional stripe order, orbital flux order, electronic nematicity and superconductivity. Here, we use high-resolution angle-resolved photoemission spectroscopy to determine the microscopic structure of three-dimensional charge order in AV3Sb5 and its interplay with superconductivity. Our approach is based on identifying an unusual splitting of kagome bands induced by three-dimensional charge order, which provides a sensitive way to refine the spatial charge patterns in neighbouring kagome planes. We found a marked dependence of the three-dimensional charge order structure on composition and doping. The observed difference between CsV3Sb5 and the other compounds potentially underpins the double-dome superconductivity in CsV3(Sb,Sn)5 and the suppression of Tc in KV3Sb5 and RbV3Sb5. Our results provide fresh insights into the rich phase diagram of AV3Sb5.
Possible microscopic structures of the 3D CO in kagome metal AV3Sb5.
Mingu Kang, Shiang Fang, Jonggyu Yoo, Brenden R. Ortiz, Yuzki M. Oey, Jonghyeok Choi, Sae Hee Ryu, Jimin Kim, Chris Jozwiak, Aaron Bostwick, Eli Rotenberg, Efthimios Kaxiras, Joseph G. Checkelsky, Stephen D. Wilson, Jae-Hoon Park & Riccardo Comin
doi: 10.1038/s41563-022-01375-2 | |
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