There is often a trade-off between mechanical properties (modulus and toughness) and dynamic self-healing. Here we report the design and synthesis of a polymer containing thermodynamically stable ...whilst kinetically labile coordination complex to address this conundrum. The Zn-Hbimcp (Hbimcp = 2,6-bis((imino)methyl)-4-chlorophenol) coordination bond used in this work has a relatively large association constant (2.2 × 10
) but also undergoes fast and reversible intra- and inter-molecular ligand exchange processes. The as-prepared Zn(Hbimcp)
-PDMS polymer is highly stretchable (up to 2400% strain) with a high toughness of 29.3 MJ m
, and can autonomously self-heal at room temperature. Control experiments showed that the optimal combination of its bond strength and bond dynamics is responsible for the material's mechanical toughness and self-healing property. This molecular design concept points out a promising direction for the preparation of self-healing polymers with excellent mechanical properties. We further show this type of polymer can be potentially used as energy absorbing material.
We propose octree-based transformers, named OctFormer, for 3D point cloud learning. OctFormer can not only serve as a general and effective backbone for 3D point cloud segmentation and object ...detection but also have linear complexity and is scalable for large-scale point clouds. The key challenge in applying transformers to point clouds is reducing the quadratic, thus overwhelming, computation complexity of attentions. To combat this issue, several works divide point clouds into non-overlapping windows and constrain attentions in each local window. However, the point number in each window varies greatly, impeding the efficient execution on GPU. Observing that attentions are robust to the shapes of local windows, we propose a novel octree attention, which leverages sorted shuffled keys of octrees to partition point clouds into local windows containing a fixed number of points while permitting shapes of windows to change freely. And we also introduce dilated octree attention to expand the receptive field further. Our octree attention can be implemented in 10 lines of code with open-sourced libraries and runs 17 times faster than other point cloud attentions when the point number exceeds 200k. Built upon the octree attention, OctFormer can be easily scaled up and achieves state-of-the-art performances on a series of 3D semantic segmentation and 3D object detection benchmarks, surpassing previous sparse-voxel-based CNNs and point cloud transformers in terms of both efficiency and effectiveness. Notably, on the challenging ScanNet200 dataset, OctFormer outperforms sparse-voxel-based CNNs by 7.3 in mIoU. Our code and trained models are available at https://wang-ps.github.io/octformer.
Inorganic chiral hybrid nanostructures that embed chirality within distinct material compositions can create novel chiral properties and functionalities absent from achiral nanostructures; however, ...they remain largely unexplored. We report, for the first time, a class of chiral plasmonic metal‐semiconductor core‐shell nanostructures that employ structurally chiral nanoparticles as chirality inducing templates to grow functional shell materials, which allowed us to independently control material parameters such as core geometry and shell thickness, as well as handedness of the system. We experimentally and theoretically achieved enhanced and tunable chiroptical activity of the heterostructures as a result of the core‐shell strong coupling effect. As a proof‐of‐concept demonstration, we demonstrate that the chiral hybrid nanostructures can drive chirality‐dependent photocatalytic hydrogen generation under circularly polarized light. This study enables rational design and functionalization of chiral hybrid nanomaterials towards enhanced chiral light–matter interactions and chiral device applications.
A novel class of chiral hybrid nanostructures comprising chiral plasmonic nanoparticles and functional semiconductors are constructed via a general synthesis. The obtained hybrids show new and tunable chiroptical activity, and exhibit chirality‐dependent photocatalytic performance of water splitting under circularly polarized light, paving the way for complex chiral nanostructures and new chiral light–matter interactions.
A room‐temperature, visible‐light‐driven N‐centered iminyl radical‐mediated and redox‐neutral C−C single bond cleavage/radical addition cascade reaction of oxime esters and unsaturated systems has ...been accomplished. The strategy tolerates a wide range of O‐acyl oximes and unsaturated systems, such as alkenes, silyl enol ethers, alkynes, and isonitrile, enabling highly selective formation of various chemical bonds. This method thus provides an efficient approach to various diversely substituted cyano‐containing alkenes, ketones, carbocycles, and heterocycles.
A visible‐light‐driven room‐temperature N‐centered iminyl radical‐mediated and redox‐neutral C−C single bond cleavage/radical addition cascade reaction of oxime esters and unsaturated systems has been accomplished. The strategy tolerates a wide range of O‐acyl oximes and alkenes, silyl enol ethers, alkynes, and isonitrile. This method allows access to various cyano‐containing alkenes, ketones, carbocycles, and heterocycles.
Flexible electronic skins (e‐skins) play a very important role in the development of human–machine interaction and wearable devices. To fully mimic the functions of human skin, e‐skins should be able ...to perceive multiple external stimuli (such as temperature, touch, and friction) and be resistant to injury. However, both objectives are highly challenging. The fabrication of multifunctional e‐skins is difficult because of the complex lamination scheme and the integration of different sensors. The design of skin‐like materials is hindered by the trade‐off problem between flexibility, toughness, and self‐healing ability. Herein, flexible sodium methallyl sulfonate functionalized poly(thioctic acid) polymer chains are combined with rigid conductive polyaniline rods through ionic bonds to obtain a solvent‐free polymer conductive gel. The conductive gel has a modulus similar to that of skin, and shows good flexibility, puncture‐resistance, notch‐insensitivity, and fast self‐healing ability. Moreover, this conductive gel can convert changes in temperature and strain into electrical signal changes, thus leading to multifunctional sensing performance. Based on these superior properties, a flexible e‐skin sensor is prepared, demonstrating its great potential in the wearable field and physiological signal detection.
A new solvent‐free polymer conductive gel is obtained by combining flexible sulfonate‐containing poly(thioctic acid) polymer chains and rigid conductive polyaniline rods. The conductive gel shows good flexibility, puncture‐resistance, notch‐insensitivity, and fast self‐healing ability. Moreover, this conductive gel can convert changes in temperature and strain into electrical signal changes, and thus can be used for multifunctional electronic skin.
Rapid industrialization in China during the last three decades has resulted in widespread contamination of Cd in agricultural soils. A considerable proportion of the rice grain grown in some areas of ...southern China has Cd concentrations exceeding the Chinese food limit, raising widespread concern regarding food safety. In this review, we summarize rice grain Cd concentrations in national Chinese markets and in field surveys from contaminated areas, and analyze the potential health risk associated with increased dietary Cd intake. For subsistence rice farmers living in some contaminated areas of southern China who mainly consume locally-produced Cd-contaminated rice, their estimated dietary Cd intake is now comparable to that for the population in the region of Japan where the Itai-Itai disease was first reported. Interventions must be taken urgently to reduce Cd intake for these farmers. We also analyze i) the main reasons causing elevated grain Cd concentrations in southern China, ii) the dominant biogeochemical processes controlling the solubility of Cd in paddy soils, and iii) molecular mechanisms for the uptake and translocation of Cd in rice plants. Based on these analyses, we propose a number of countermeasures to address soil Cd contamination, including i) mitigation of Cd transfer from paddy soils to rice grain, and ii) intervention in those farmers who consume home-grown Cd-contaminated rice. Liming to increase soil pH to 6.5 and gene editing biotechnology are effective strategies to decrease Cd accumulation in rice grain. For these local farmers with high-Cd exposure risk, local governments should monitor the Cd concentration in their home-grown rice and exchange those high-Cd rice with low-Cd rice in order to reduce their dietary Cd intake.
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•We review the status of Cd contamination in soils and rice grain in China.•We summarize the biogeochemical processes and molecular tools to produce Cd-safe rice.•We propose a number of countermeasures to tackle soil Cd contamination.•Interventions are required for the local farmers consuming Cd-contaminated rice.
This review analyzes the current status of Cd contamination in agricultural soils and rice grain in China and proposes strategies to tackle this issue, including mitigation and intervention measurements.
Spin pumping (SP) and inverse spin Hall effect (ISHE) driven by parametrically-excited dipole-exchange spin waves in a yttrium iron garnet film have been systematically investigated. The measured ...voltage spectrum exhibits a feature of the field-induced transition from parallel pumping to perpendicular pumping because of the inhomogeneous excitation geometry. Thanks to the high precision of the SP-ISHE detection, two sets of fine structures in the voltage spectrum are observed, which can correspond well to two kinds of critical points in the multimode spin-wave spectrum for magnetic films. One is the
q
= 0 point of each higher-order dispersion branch, and the other is the local minimum due to the interplay between the dipolar and exchange interactions. These fine structures on the voltage spectrum confirm the spin pumping by higher-order dipole-exchange spin-wave modes, and are helpful for probing the multimode spin-wave spectrum.
A fault diagnosis approach based on multi-sensor data fusion is a promising tool to deal with complicated damage detection problems of mechanical systems. Nevertheless, this approach suffers from two ...challenges, which are (1) the feature extraction from various types of sensory data and (2) the selection of a suitable fusion level. It is usually difficult to choose an optimal feature or fusion level for a specific fault diagnosis task, and extensive domain expertise and human labor are also highly required during these selections. To address these two challenges, we propose an adaptive multi-sensor data fusion method based on deep convolutional neural networks (DCNN) for fault diagnosis. The proposed method can learn features from raw data and optimize a combination of different fusion levels adaptively to satisfy the requirements of any fault diagnosis task. The proposed method is tested through a planetary gearbox test rig. Handcraft features, manual-selected fusion levels, single sensory data, and two traditional intelligent models, back-propagation neural networks (BPNN) and a support vector machine (SVM), are used as comparisons in the experiment. The results demonstrate that the proposed method is able to detect the conditions of the planetary gearbox effectively with the best diagnosis accuracy among all comparative methods in the experiment.
We examined relationships among transformational leadership, employee identification with leader, innovative climate, and employee creativity in a diverse sample of 212 employees and their immediate ...supervisors from 71 workgroups representing 55 organizations. Results from multi-level linear modeling analyses indicated that transformational leadership was not significantly related with employee creativity, nor were the two way interactions of transformational leadership × identification with leader and transformation leadership × innovative climate. However, the three-way interaction of transformational leadership, employee identification with leader, and innovative climate was associated with employee creativity. We discuss the implications of these findings for practice and theory.
The human brain is a sophisticated, high‐performance biocomputer that processes multiple complex tasks in parallel with high efficiency and remarkably low power consumption. Scientists have long been ...pursuing an artificial intelligence (AI) that can rival the human brain. Spiking neural networks based on neuromorphic computing platforms simulate the architecture and information processing of the intelligent brain, providing new insights for building AIs. The rapid development of materials engineering, device physics, chip integration, and neuroscience has led to exciting progress in neuromorphic computing with the goal of overcoming the von Neumann bottleneck. Herein, fundamental knowledge related to the structures and working principles of neurons and synapses of the biological nervous system is reviewed. An overview is then provided on the development of neuromorphic hardware systems, from artificial synapses and neurons to spike‐based neuromorphic computing platforms. It is hoped that this review will shed new light on the evolution of brain‐like computing.
Spiking neural networks based on neuromorphic computing platforms simulate the architecture and information processing of the brain, providing a new insight for building machines having artificial intelligence. A comprehensive overview of the development of neuromorphic engineering from biological nervous systems to spike‐based neuromorphic computing platforms is provided.
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