Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and finite conductivity only employing naturally available materials. It is demonstrated that the thermal localization inside the coating layer can be tuned and controlled robustly by anisotropy, which enables an incomplete cloak to function perfectly. Practical realization of such homogeneous thermal cloak has been suggested by using two naturally occurring conductive materials, which provides an unprecedentedly plausible way to flexibly realize thermal cloak and manipulate heat flow with phonons.

It remains a challenge to fabricate healable and recyclable polymeric materials with simultaneously enhanced tensile strength, stretchability, and toughness. Herein, we report a simple approach to fabricate high-performance polymer hydrogels that not only integrate high tensile strength, stretchability, and toughness but also possess selfhealing and recycling capabilities. The polymer hydrogels are fabricated by mixing a positively charged polyelectrolyte mixture of poly(diallyldimethylammonium chloride) (PDDA)/branched poly(ethylenimine) (PEI) with a negatively charged polyelectrolyte mixture of poly(sodium 4styrenesulfonate) (PSS)/poly(acrylic acid) (PAA) in an aqueous solution followed by molding, drying, and rehydration. The (PDDA/PEI)−(PSS/PAA) hydrogels with in situ-formed PDDA−PSS nanoparticles have a tensile strength, strain at break, and toughness of 1.26 ± 0.06 MPa, 2434.2 ± 150.3%, and 19.53 ± 0.48 MJ/m 3 , respectively. The toughness of the (PDDA/PEI)− (PSS/PAA) hydrogels is ∼5.2 and ∼108 times higher than that of the PEI−PAA and PDDA−PSS hydrogels, respectively. Benefiting from the high reversibility of the hydrogen-bonding and electrostatic interactions, the (PDDA/PEI)−(PSS/PAA) hydrogels can efficiently heal from physical damage to restore their original mechanical properties at room temperature in water. Moreover, the (PDDA/PEI)−(PSS/PAA) hydrogels after being dried and ground can be recycled under a pressure of ∼3 kPa at room temperature in the presence of water to reuse the damaged hydrogels.

A superhydrophilic and underwater superoleophobic PVDF membrane (PVDFAH) has been prepared by surface-coating of a hydrogel onto the membrane surface, and its superior performance for oil/water emulsion separation has been demonstrated. The coated hydrogel was constructed by an interfacial polymerization based on the thiol-epoxy reaction of pentaerythritol tetrakis (3-mercaptopropionate) (PETMP) with diethylene glycol diglycidyl ether (PEGDGE) and simultaneously tethered on an alkaline-treated commercial PVDF membrane surface via the thio-ene reaction. The PVDFAH membranes can be fabricated in a few minutes under mild conditions and show superhydrophilic and underwater superoleophobic properties for a series of organic solvents. Energy dispersive X-ray (EDX) analysis shows that the hydrogel coating was efficient throughout the pore lumen. The membrane shows superior oil/water emulsion separation performance, including high water permeation, quantitative oil rejection, and robust antifouling performance in a series oil/water emulsions, including that prepared from crude oil. In addition, a 24 h Soxhlet-extraction experiment with ethanol/water solution (50:50, v/v) was conducted to test the tethered hydrogel stability. We see that the membrane maintained the water contact angle below 5°, indicating the covalent tethering stability. This technique shows great promise for scalable fabrication of membrane materials for handling practical oil emulsion purification.

ObjectiveTo develop a deep convolutional neural network (DCNN) that can automatically detect laryngeal cancer (LCA) in laryngoscopic images.MethodsA DCNN-based diagnostic system was constructed and trained using 13,721 laryngoscopic images of LCA, precancerous laryngeal lesions (PRELCA), benign laryngeal tumors (BLT) and normal tissues (NORM) from 2 tertiary hospitals in China, including 2293 from 206 LCA subjects, 1807 from 203 PRELCA subjects, 6448 from 774 BLT subjects and 3191 from 633 NORM subjects. An independent test set of 1176 laryngoscopic images from other 3 tertiary hospitals in China, including 132 from 44 LCA subjects, 129 from 43 PRELCA subjects, 504 from 168 BLT subjects and 411 from 137 NORM subjects, was applied to the constructed DCNN to evaluate its performance against experienced endoscopists.ResultsThe DCCN achieved a sensitivity of 0.731, a specificity of 0.922, an AUC of 0.922, and the overall accuracy of 0.867 for detecting LCA and PRELCA among all lesions and normal tissues. When compared to human experts in an independent test set, the DCCN’ s performance on detection of LCA and PRELCA achieved a sensitivity of 0.720, a specificity of 0.948, an AUC of 0.953, and the overall accuracy of 0.897, which was comparable to that of an experienced human expert with 10–20 years of work experience. Moreover, the overall accuracy of DCNN for detection of LCA was 0.773, which was also comparable to that of an experienced human expert with 10–20 years of work experience and exceeded the experts with less than 10 years of work experience.ConclusionsThe DCNN has high sensitivity and specificity for automated detection of LCA and PRELCA from BLT and NORM in laryngoscopic images. This novel and effective approach facilitates earlier diagnosis of early LCA, resulting in improved clinical outcomes and reducing the burden of endoscopists.

Controlling electromagnetic energy is essential for an efficient and sustainable society. A key requirement is concentrating magnetic energy in a desired volume of space in order to either extract the energy to produce work or store it. Metamaterials have opened new possibilities for controlling electromagnetic energy [1,2]. Recently, a superconductor-ferromagnetic metamaterial that allows unprecedented concentration and amplification of magnetic energy, and also its transmission at distance through free space, has been devised theoretically [3]. Here we design and build an actual version of the superconductor-ferromagnetic metamaterial and experimentally confirm these properties. We show that also a ferromagnetic metamaterial, without superconducting parts, can achieve concentration and transmission of energy with only a slight decrease in the performance. Transmission of magnetic energy at a distance by magnetic metamaterials may provide new ways of enhancing wireless power transmission, where efficiency depends critically on the magnetic coupling strength between source and receiver.