The high fracture toughness of mollusk nacre is predominantly attributed to the structure‐associated extrinsic mechanisms such as platelet sliding and crack deflection. While the nacre‐mimetic ...structures are widely adopted in artificial ceramics, the extrinsic mechanisms are often weakened by the relatively low tensile strength of the platelets with a large aspect ratio, which makes the fracture toughness of these materials much lower than expected. Here, it is demonstrated that the fracture toughness of artificial nacre materials with high inorganic contents can be improved by residual stress‐induced platelet strengthening, which can catalyze more effective extrinsic toughening mechanisms that are specific to the nacre‐mimetic structures. Thereby, while the absolute fracture toughness of the materials is not comparable with advanced ceramic‐based composites, the toughness amplification factor of the material reaches 16.1 ± 1.1, outperforming the state‐of‐the‐art biomimetic ceramics. The results reveal that, with the merit of nacre‐mimetic structural designs, the overall fracture toughness of the artificial nacre can be improved by the platelet strengthening through extrinsic toughening mechanisms, although the intrinsic fracture toughness may decrease at platelet level due to the strengthening. It is anticipated that advanced structural ceramics with exceeding performance can be fabricated through these unconventional strategies.
This work illustrates an anti‐intuitive strategy that, with the merit of biomimetic designs, residual stress that is conventionally harmful to ceramics can inversely help improve the fracture toughness of biomimetic ceramics through nanoscale residual stress‐induced platelet strengthening. This provides new insights into the design principles of nacre‐like materials at the bottom level.
Soft polymer materials, which are similar to human tissues, have played critical roles in modern interdisciplinary research. Compared with conventional methods, 3D printing allows rapid prototyping ...and mass customization and is ideal for processing soft polymer materials. However, 3D printing of soft polymer materials is still in the early stages of development and is facing many challenges including limited printable materials, low printing resolution and speed, and poor functionalities. The present review aims to summarize the ideas to address these challenges. It focuses on three points: 1) how to develop printable materials and make unprintable materials printable, 2) how to choose suitable methods and improve printing resolution, and 3) how to directly construct functional structures/systems with 3D printing. After a brief introduction on this topic, the mainstream 3D printing technologies for printing soft polymer materials are reviewed, with an emphasis on improving printing resolution and speed, choosing suitable printing techniques, developing printable materials, and printing multiple materials. Moreover, the state‐of‐the‐art advancements in multimaterial 3D printing of soft polymer materials are summarized. Furthermore, the revolutions brought about by 3D printing of soft polymer materials for applications similar to biology are highlighted. Finally, viewpoints and future perspectives for this emerging field are discussed.
3D printing of soft polymer materials allows the rapid prototyping of functional soft architectures in a highly integrated way. Herein, the recent advancements in this emerging topic are reviewed based on a target to improve its printing speed, resolution, printable material, and functionalities. The trends of multimaterial 3D printing are discussed and the perspectives for this emerging field are provided.
Ultrathick electrode design is a promising strategy to enhance the specific energy of Li‐ion batteries (LIBs) without changing the underlying materials chemistry. However, the low Li‐ion conductivity ...caused by ultralong Li‐ion transport pathway in traditional random microstructured electrode heavily deteriorates the rate performance of ultrathick electrodes. Herein, inspired by the vertical microchannels in natural wood as the highway for water transport, the microstructures of wood are successfully duplicated into ultrathick bulk LiCoO2 (LCO) cathode via a sol–gel process to achieve the high areal capacity and excellent rate capability. The X‐ray‐based microtomography demonstrates that the uniform microchannels are built up throughout the whole wood‐templated LCO cathode bringing in 1.5 times lower of tortuosity and ≈2 times higher of Li‐ion conductivity compared to that of random structured LCO cathode. The fabricated wood‐inspired LCO cathode delivers high areal capacity up to 22.7 mAh cm−2 (five times of the existing electrode) and achieves the dynamic stress test at such high areal capacity for the first time. The reported wood‐inspired design will open a new avenue to adopt natural hierarchical structures to improve the performance of LIBs.
Inspired by the vertical microchannels in natural wood as the highway for water transport, an ultra‐thick bulk LiCoO2 (LCO) cathode with vertical channels is fabricated to enhance the transport of Li+. Remarkably, the fabricated LCO cathode shows low tortuosity and high Li‐ion conductivity, and can deliver high areal capacity up to 22.7 mAh cm−2.
Liquid‐metal (LM)‐based flexible and stretchable electronics have attracted widespread interest in wearable computing, human–machine interaction, and soft robotics. However, many current examples are ...one‐off prototypes, whereas future implementation requires mass production. To address this critical challenge, an integrated multimaterial 3D printing process composed of direct ink writing (DIW) of sealing silicone elastomer and special LM‐silicone (LMS) inks for manufacturing high‐performance LM‐based flexible and stretchable electronics is presented. The LMS ink is a concentrated mixture of LM microdroplets and silicone elastomer and exhibits excellent printability for DIW printing. Guided by a verified theoretical model, a printing process with high resolution and high speed can be easily implemented. Although LMS is not initially conductive, it can be activated by pressing or freezing. Activated LMS possesses good conductivity and significant electrical response to strain. Owing to LMS's unique structure, LMS‐embedded flexible electronics exhibit great damage mitigation, in that no leaking occurs even when damaged. To demonstrate the flexibility of this process in fabricating LM‐based flexible electronics, multilayer soft circuits, strain sensors, and data gloves are printed and investigated. Notably, utilizing LMS's unique activating property, some functional circuits such as one‐time pressing/freezing‐on switch can be printed without any structural design.
A special liquid‐metal–silicone (LMS) ink and corresponding multimaterial printing process are developed for fabricating all‐printed flexible and stretchable electronics. It exhibits excellent printability and good conductivity, significant electrical response to deformation, and great reliability. Thanks to these, all‐printed flexible electronics with high throughput, resolution, and device reliability can be easily fabricated.
A compact two-antenna building block for forming the multiple-input multiple-output (MIMO) array in the mobile device such as the smartphone is presented. The building block has a planar structure of ...small size 7 × 10 mm 2 (about 0.08λ × 0.12λ) for operating at 3.5-GHz band (3.4-3.6 GHz), which is the recently identified frequency spectrum in World Radiocommunication Conference 2015 for future broadband mobile services. The building block is formed by two gap-coupled loop antennas having asymmetrically mirrored (AM) structures with respect to the system ground plane of the smartphone. The two AM antennas show good isolation thereof and their envelope correlation coefficient is much less than 0.1 in the operating band, showing very good independence of the two antennas in their far-field radiation characteristics. By using four such building blocks, an eight-antenna MIMO array at 3.5-GHz band in the smartphone is easily implemented. The channel capacity of the eight-antenna MIMO array in an 8 \× 8 MIMO system is calculated to be about 36 b/s/Hz with 20-dB signal-to-noise ratio. The measured channel capacity obtained using an 8 × 8 MIMO measurement setup is also presented, which generally agrees with the calculated results. The obtained eight-antenna MIMO array is promising for future or fifth-generation smartphone applications.
The propensity of the activated neutrophils to form extracellular traps (NETs) is demonstrated in multiple inflammatory conditions. In this study, we investigated the roles of NETs in metastasis of ...hepatocellular carcinoma (HCC) and further explored the underlying mechanism of how NETs affect metastasis as well as the therapeutic value.
The neutrophils were isolated from the blood of human HCC patients and used to evaluate the formation of NETs. The expression of NET markers was detected in tumor specimens. A LPS-induced NET model was used to investigate the role of NETs on HCC metastasis. RNA-seq was performed to identify the key molecular event triggered by NETs, and their underlying mechanism and therapeutic significance were explored using both in vitro and in vivo assays.
NET formation was enhanced in neutrophils derived from HCC patients, especially those with metastatic HCCs. NETs trapped HCC cells and subsequently induced cell-death resistance and enhanced invasiveness to trigger their metastatic potential, which was mediated by internalization of NETs into trapped HCC cells and activation of Toll-like receptors TLR4/9-COX2 signaling. Inhibition of TLR4/9-COX2 signaling abrogated the NET-aroused metastatic potential. A combination of DNase 1 directly wrecking NETs with anti-inflammation drugs aspirin/hydroxychloroquine effectively reduced HCC metastasis in mice model.
NETs trigger tumorous inflammatory response and fuel HCC metastasis. Targeting NETs rather than neutrophils themselves can be a practice strategy against HCC metastasis.
Exceptional points (EPs) are special spectral degeneracies of non-Hermitian Hamiltonians that govern the dynamics of open systems. At an EP, two or more eigenvalues, and the corresponding ...eigenstates, coalesce
. Recently, it was predicted that operation of an optical gyroscope near an EP results in improved response to rotations
. However, the performance of such a system has not been examined experimentally. Here we introduce a precisely controllable physical system for the study of non-Hermitian physics and nonlinear optics in high-quality-factor microresonators. Because this system dissipatively couples counter-propagating lightwaves within the resonator, it also functions as a sensitive gyroscope for the measurement of rotations. We use our system to investigate the predicted EP-enhanced Sagnac effect
and observe a four-fold increase in the Sagnac scale factor by directly measuring rotations applied to the resonator. The level of enhancement can be controlled by adjusting the system bias relative to the EP, and modelling results confirm the observed enhancement. Moreover, we characterize the sensitivity of the gyroscope near the EP. Besides verifying EP physics, this work is important for the understanding of optical gyroscopes.
Optical gyroscopes are among the most accurate rotation measuring devices and are widely used for navigation and accurate pointing. Since the advent of photonic integrated components for ...communications, and with their increasing complexity, there has been interest in the possibility of chip-scale optical gyroscopes1. Besides the potential benefits of integration, such solid-state systems would be robust and resistant to shock. Here, we report a gyroscope using Brillouin ring lasers on a silicon chip. Its stability and sensitivity enable measurement of Earth’s rotation, representing a major milestone for this new class of gyroscope.A Sagnac gyroscope based on Brillouin ring lasers on a silicon chip is presented. The stability and sensitivity of this on-chip planar gyroscope allow measurement of the Earth’s rotation, with an amplitude sensitivity as small as 5 deg h−1 for a sinusoidal rotation, an angle random walk of 0.068 deg h−1/2 and bias instability of 3.6 deg h−1.
The asymmetric formal hydroamination of enamines using a CuH catalyst is reported. The method provides a straightforward and efficient approach to the synthesis of chiral 1,2‐dialkyl amines in good ...yields with high levels of enantioselectivities for a broad range of substrates, and should have significant value for the preparation of molecules bearing a 1,2‐diamine motif.
The old one‐two: The asymmetric formal hydroamination of enamines using a CuH catalyst is reported. This method provides a straightforward and efficient approach to the synthesis of chiral 1,2‐dialkyl amines in good yields with high levels of enantioselectivities for a broad range of substrates, and should have significant value for the preparation of molecules bearing a 1,2‐diamine motif.
Active carbons have unique physicochemical properties, but their conductivities and surface to weight ratios are much poorer than graphene. A unique and facile method is innovated to chemically ...process biomass by “drilling” holes with H2O2 and exfoliating into graphene‐like nanosheets with HAc, followed by carbonization at a high temperature for highly graphitized activated carbon with greatly enhanced porosity, unique pore structure, high conductivity, and large surface area. This graphene‐like carbon exhibits extremely high specific capacitance (340 F g−1 at 0.5 A g−1) and high specific energy density (23.33 to 16.67 W h kg−1) with excellent rate capability and long cycling stability (remains 98% after 10 000 cycles), which is much superior to all reported carbons including graphene. Synthesis mechanism for deriving biomass into porous graphene‐like carbons is discussed in detail. The enhancement mechanism for the porous graphene‐like carbon electrode reveals that rationally designed meso‐ and macropores are very critical in porous electrode performance, which can network micropores for diffusion freeways, high conductivity, and high utilization. This work has universal significance in producing highly porous and conductive carbons from biomass including biowastes for various energy storage/conversion applications.
A graphene‐like porous activated carbon derived from a biomass fabricated, rationally designed chemical process, followed by carbonization at high temperature, exhibits a specific capacitance of 340 F g−1 at 0.5 A g−1 and high specific energy density (23.33–16.67 W h kg−1), with excellent capacity retention after 10 000 cycles, superior to other carbon electrodes.
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