With the ever‐increasing adaption of large‐scale energy storage systems and electric devices, the energy storage capability of batteries and supercapacitors has faced increased demand and challenges. ...The electrodes of these devices have experienced radical change with the introduction of nano‐scale materials. As new generation materials, heterostructure materials have attracted increasing attention due to their unique interfaces, robust architectures, and synergistic effects, and thus, the ability to enhance the energy/power outputs as well as the lifespan of batteries. In this review, the recent progress in heterostructure from energy storage fields is summarized. Specifically, the fundamental natures of heterostructures, including charge redistribution, built‐in electric field, and associated energy storage mechanisms, are summarized and discussed in detail. Furthermore, various synthesis routes for heterostructures in energy storage fields are roundly reviewed, and their advantages and drawbacks are analyzed. The superiorities and current achievements of heterostructure materials in lithium‐ion batteries (LIBs), sodium‐ion batteries (SIBs), lithium‐sulfur batteries (Li‐S batteries), supercapacitors, and other energy storage devices are discussed. Finally, the authors conclude with the current challenges and perspectives of the heterostructure materials for the fields of energy storage.
Constructing heterostructures is an effective way to enhance the electrochemical performance of active materials due to the unique heterointerface structure and some unrevealed synergistic effects. An overview of the recent advancements in heterostructured materials in terms of enhanced mechanism, synthesis techniques, and electrochemical performance is provided. Future development trends for design of heterostructured electrodes are analyzed.
Polymeric hydrogel actuators refer to intelligent stimuli‐responsive hydrogels that could reversibly deform upon the trigger of various external stimuli. They have thus aroused tremendous attention ...and shown promising applications in many fields including soft robots, artificial muscles, valves, and so on. After a brief introduction of the driving forces that contribute to the movement of living creatures, an overview of the design principles and development history of hydrogel actuators is provided, then the diverse anisotropic structures of hydrogel actuators are summarized, presenting the promising applications of hydrogel actuators, and highlighting the development of multifunctional hydrogel actuators. Finally, the existing challenges and future perspectives of this exciting field are discussed.
As one of the most important stimuli‐responsive materials, biomimetic hydrogel actuators have attracted increased attention. Here, the driving forces that contribute to the movement of living creatures are introduced, and the design principles, diverse anisotropic structures, as well as promising applications of hydrogel actuators are summarized. Finally, the challenges and future outlooks of this field are discussed.
Proton exchange membrane fuel cells (PEMFCs) with high efficiency and nonpollution characteristics have attracted massive attention from both academic and industrial communities due to their ...irreplaceable roles in building the future sustainable energy system. However, the stability issue of Pt‐based catalysts for oxygen reduction reaction (ORR) has become a central constraint to the widespread deployment of the devices relative to the catalytic activity. This review aims to provide comprehensive insights into how to improve the stability of Pt‐based catalysts for ORR. First, the basic physical chemistry behind the catalyst degradation, including the fundamental understandings of carbon corrosion, catalyst dissolution, and particle sintering, is highlighted. After a discussion of advanced characterization techniques for the catalyst degradation, the design strategies for improving the stability of Pt‐based catalysts are summarized. Finally, further insights into the remaining challenges and future research directions are also provided.
Strategies to improve the stability of Pt‐based catalysts for the oxygen reduction reaction are comprehensively reviewed. The basic physical chemistry behind the catalyst degradation is highlighted. After a discussion of advanced characterization techniques for the catalyst degradation, design strategies for improving the stability of Pt‐based catalysts are proposed.
A survey of heterogeneous information network analysis Chuan Shi; Yitong Li; Jiawei Zhang ...
IEEE transactions on knowledge and data engineering,
2017-Jan.-1, 2017-1-1, 20170101, Volume:
29, Issue:
1
Journal Article
Peer reviewed
Open access
Most real systems consist of a large number of interacting, multi-typed components, while most contemporary researches model them as homogeneous information networks, without distinguishing different ...types of objects and links in the networks. Recently, more and more researchers begin to consider these interconnected, multi-typed data as heterogeneous information networks, and develop structural analysis approaches by leveraging the rich semantic meaning of structural types of objects and links in the networks. Compared to widely studied homogeneous information network, the heterogeneous information network contains richer structure and semantic information, which provides plenty of opportunities as well as a lot of challenges for data mining. In this paper, we provide a survey of heterogeneous information network analysis. We will introduce basic concepts of heterogeneous information network analysis, examine its developments on different data mining tasks, discuss some advanced topics, and point out some future research directions.
Interpretation and diagnosis of machine learning models have gained renewed interest in recent years with breakthroughs in new approaches. We present Manifold, a framework that utilizes visual ...analysis techniques to support interpretation, debugging, and comparison of machine learning models in a more transparent and interactive manner. Conventional techniques usually focus on visualizing the internal logic of a specific model type (i.e., deep neural networks), lacking the ability to extend to a more complex scenario where different model types are integrated. To this end, Manifold is designed as a generic framework that does not rely on or access the internal logic of the model and solely observes the input (i.e., instances or features) and the output (i.e., the predicted result and probability distribution). We describe the workflow of Manifold as an iterative process consisting of three major phases that are commonly involved in the model development and diagnosis process: inspection (hypothesis), explanation (reasoning), and refinement (verification). The visual components supporting these tasks include a scatterplot-based visual summary that overviews the models' outcome and a customizable tabular view that reveals feature discrimination. We demonstrate current applications of the framework on the classification and regression tasks and discuss other potential machine learning use scenarios where Manifold can be applied.
Numerous efforts have been made to design various low-level saliency cues for RGBD saliency detection, such as color and depth contrast features as well as background and color compactness priors. ...However, how these low-level saliency cues interact with each other and how they can be effectively incorporated to generate a master saliency map remain challenging problems. In this paper, we design a new convolutional neural network (CNN) to automatically learn the interaction mechanism for RGBD salient object detection. In contrast to existing works, in which raw image pixels are fed directly to the CNN, the proposed method takes advantage of the knowledge obtained in traditional saliency detection by adopting various flexible and interpretable saliency feature vectors as inputs. This guides the CNN to learn a combination of existing features to predict saliency more effectively, which presents a less complex problem than operating on the pixels directly. We then integrate a superpixel-based Laplacian propagation framework with the trained CNN to extract a spatially consistent saliency map by exploiting the intrinsic structure of the input image. Extensive quantitative and qualitative experimental evaluations on three data sets demonstrate that the proposed method consistently outperforms the state-of-the-art methods.
As one of the most outstanding materials, the analysis of the structure and function of hydrogels has been extensively carried out to tailor and adapt them to various fields of application. The high ...water content, which is beneficial for plenty of applications in the biomedical setting, prevents the adoption of hydrogels in flexible electronics and sensors in real life applications, because hydrogels lose their excellent properties, including conductivity, transparency, flexibility, etc., upon freezing at sub-zero temperatures. Therefore, depressing the liquid-solid phase transition temperature is a powerful means to expand the application scope of hydrogels, and will benefit the chemical engineering and materials science communities. This review summarizes the recent research progress of anti-freezing hydrogels. At first, approaches for the generation of anti-freezing (hydro)gels are introduced and their anti-freezing mechanisms and performances are briefly discussed. These approaches are either based on addition of salts, alcohols (cryoprotectants and organohydrogels), and ionic liquids (ionogels), modification of the polymer network or a combination of several techniques. Then, a concise overview of applications leveraged by the widened temperature resistance is provided and future research areas and developments are envisaged.
n‐type Mg3Sb2‐based compounds have emerged as a promising class of low‐cost thermoelectric materials due to their extraordinary performance at low and intermediate temperatures. However, so far, high ...thermoelectric performance has merely been reported in n‐type Mg3Sb2‐Mg3Bi2 alloys with a large amount of Bi. Moreover, current synthesis methods of n‐type Mg3Sb2 bulk thermoelectrics involve multi‐step processes that are time‐ and energy‐consuming. Herein, we report a fast and straightforward approach to fabricate n‐type Mg3Sb2 thermoelectrics using spark plasma sintering, which combines the synthesis and compaction in one step. Using this method, we achieve a high thermoelectric figure of merit zT of about 0.4–1.5 at 300–725 K in n‐type (Sc, Te)‐co‐doped Mg3Sb2 without alloying with Mg3Bi2. In comparison with the currently reported synthesis methods, the complexity, process time, and cost of our method are significantly reduced. This work demonstrates a simple, low‐cost route for the potential large‐scale production of n‐type Mg3Sb2 thermoelectrics.
A simple one‐step approach is developed for preparing high‐performance low‐cost n‐type (Sc, Te)‐doped Mg3Sb2 thermoelectric materials that show a high optimal thermoelectric figure of merit zT of about 1.5 and a high average zT of about 0.9 at 300–725 K. The approach provides a new avenue for the rapid, low‐cost, and large‐scale production of n‐type Mg3Sb2 thermoelectrics.
Many living organisms have amazing control over their color, shape, and morphology for camouflage, communication, and even reproduction in response to interplay between environmental stimuli. Such ...interesting phenomena inspire scientists to develop smart soft actuators/robotics via integrating color‐changing functionality based on polymer films or elastomers. However, there has been no significant progress in synergistic color‐changing and shape‐morphing capabilities of life‐like material systems such as hydrogels. Herein, we reported a new class of bioinspired synergistic fluorescence‐color‐switchable polymeric hydrogel actuators based on supramolecular dynamic metal–ligand coordination. Artificial hydrogel apricot flowers and chameleons have been fabricated for the first time, in which simultaneous color‐changing and shape‐morphing behaviors are controlled by the subtle interplay between acidity/alkalinity, metal ions, and temperature. This work has made color‐changeable soft machines accessible and is expected to hold wide potential applications in biomimetic soft robotics, biological sensors, and camouflage.
Apricot blossoms and chameleons inspired the development of color‐changing bilayer soft actuators based on smart multicolor fluorescent hydrogels that assemble via dynamic metal coordination. The emission color and 3D shape of actuator constructs change in response to changes in temperature, acidity/alkalinity, and metal ions.
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