Solid‐oxide fuel cells (SOFCs) are electricity generators that can convert the chemical energy in various fuels directly to the electric power with high efficiency. Recent advances in materials and ...related key components for SOFCs operating at ≈500 °C are summarized here, with a focus on the materials, structures, and techniques development for low‐temperature SOFCs, including the analysis of most of the critical parameters affecting the electrochemical performance of the electrolyte, anode, and cathode. New strategies, such as thin‐film deposition, exsolution of nanoparticles from perovskites, microwave plasma heating, and finger‐like channeled electrodes, are discussed. These recent developments highlight the need for electrodes with higher activity and electrolytes with greater conductivity to generate a high electrochemical performance at lower temperatures.
Recent new materials, structures, and techniques for low‐temperature solid‐oxide fuel cells operating at around 500 °C are discussed. A theoretical analysis of critical parameters affecting the electrochemical properties is introduced. The discussion of the materials is divided into three sections, i.e., electrolyte, anode, and cathode. Some new strategies, such as thin‐film deposition, are also considered.
Stereoscopic video quality assessment (SVQA) is a challenging problem. It has not been well investigated on how to measure depth perception quality independently under different distortion categories ...and degrees, especially exploit the depth perception to assist the overall quality assessment of 3D videos. In this paper, we propose a new depth perception quality metric (DPQM) and verify that it outperforms existing metrics on our published 3D video extension of High Efficiency Video Coding (3D-HEVC) video database. Furthermore, we validate its effectiveness by applying the crucial part of the DPQM to a novel blind stereoscopic video quality evaluator (BSVQE) for overall 3D video quality assessment. In the DPQM, we introduce the feature of auto-regressive prediction-based disparity entropy (ARDE) measurement and the feature of energy weighted video content measurement, which are inspired by the free-energy principle and the binocular vision mechanism. In the BSVQE, the binocular summation and difference operations are integrated together with the fusion natural scene statistic measurement and the ARDE measurement to reveal the key influence from texture and disparity. Experimental results on three stereoscopic video databases demonstrate that our method outperforms state-of-theart SVQA algorithms for both symmetrically and asymmetrically distorted stereoscopic video pairs of various distortion types.
Football is a very dangerous sport. In order to reduce the injury of athletes, we must have corresponding protective articles, and the materials used are very important. Foam material has attracted ...the attention of all circles for its light weight, high strength, strong absorption impact load, and good heat insulation performance. However, the mechanical properties of foam materials will decrease with the decrease of density, which limits their application in sports, especially in some sports occasions, such as motorcycle competition, football, and other sports protection. In this paper, HGB/TPU foam materials are mainly studied. The material not only has good shock absorption performance but also has light weight and good mechanical properties. It can be used as protective equipment for football. In this paper, HGB/TPU composite foam materials were prepared by extrusion foaming method using TPU and HGB as raw materials. The effects of HGB surface modification, foaming agent content, and HGB content on the cellular structure and mechanical properties of composite foams were also investigated. The experimental results show that when the foaming method is extrusion foaming, the content of HGB is 3% and the content of foaming agent is 1.5%. It has better resistance to external forces, which helps to protect athletes from serious injuries.
Synthetic dimensions based on particles' internal degrees of freedom, such as frequency, spatial modes and arrival time, have attracted significant attention. They offer ideal large-scale lattices to ...simulate nontrivial topological phenomena. Exploring more synthetic dimensions is one of the paths toward higher dimensional physics. In this work, we design and experimentally control the coupling among synthetic dimensions consisting of the intrinsic photonic orbital angular momentum and spin angular momentum degrees of freedom in a degenerate optical resonant cavity, which generates a periodically driven spin-orbital coupling system. We directly characterize the system's properties, including the density of states, energy band structures and topological windings, through the transmission intensity measurements. Our work demonstrates a mechanism for exploring the spatial modes of twisted photons as the synthetic dimension, which paves the way to design rich topological physics in a highly compact platform.
Metal–organic frameworks (MOFs) with high porosity usually exhibit weak mechanical stabilities, in particular, rather low stabilities against shear stress. This limitation remains one of the ...bottlenecks for certain applications of porous MOFs, such as gas storage or separation that requires dense packing of the MOF powders under mechanical compression without collapsing the pores. We found that UiO-66, a prototypical Zr-MOF with high porosity, exhibits unusually high shear stability. Its minimal shear modulus (G min = 13.7 GPa) is an order of magnitude higher than those of other benchmark highly porous MOFs (e.g., MOF-5, ZIF-8, HKUST-1), approaching that of zeolites. Our analysis clearly shows that the exceptional mechanical stability of UiO-66 is due to its high framework connections (i.e., the high degree of coordination of Zr–O metal centers to the organic linkers). Our work thus provides important guidelines for developing new porous MOFs targeting at high mechanical stabilities.
Hydrogen-bonded organic frameworks (HOFs) represent an interesting type of polymeric porous materials that can be self-assembled through H-bonding between organic linkers. To realize permanent ...porosity in HOFs, stable and robust open frameworks can be constructed by judicious selection of rigid molecular building blocks and hydrogen-bonded units with strong H-bonding interactions, in which the framework stability might be further enhanced through framework interpenetration and other types of weak intermolecular interactions such as π π interactions. Owing to the reversible and flexible nature of H-bonding connections, HOFs show high crystallinity, solution processability, easy healing and purification. These unique advantages enable HOFs to be used as a highly versatile platform for exploring multifunctional porous materials. Here, the bright potential of HOF materials as multifunctional materials is highlighted in some of the most important applications for gas storage and separation, molecular recognition, electric and optical materials, chemical sensing, catalysis, and biomedicine.
This review provides an overview of development in the design, synthesis, and application of multifunctional porous hydrogen-bonded organic framework (HOF) materials.
As technology continues to advance, science fiction films are adopting new narrative forms. The Hollywood-produced film “Dune” follows the traditional narrative model while also absorbing elements ...from popular culture, thus becoming a new type of secular mythology. It takes the traditional narrative model one step further and becomes what Deleuze describes as a new paradigm of cinematic narrative, known as “pure optical and sound situations”. By studying the narrative logic and style of “Dune” through the theoretical paradigm of narratology, we can not only focus on the changes in the narrative content and form of science fiction films in the era of streaming media but also explore the aesthetic meaning of science fiction embedded within it.
One challenge for the commercial development of solid oxide fuel cells as efficient energy-conversion devices is thermo-mechanical instability. Large internal-strain gradients caused by the mismatch ...in thermal expansion behaviour between different fuel cell components are the main cause of this instability, which can lead to cell degradation, delamination or fracture
. Here we demonstrate an approach to realizing full thermo-mechanical compatibility between the cathode and other cell components by introducing a thermal-expansion offset. We use reactive sintering to combine a cobalt-based perovskite with high electrochemical activity and large thermal-expansion coefficient with a negative-thermal-expansion material, thus forming a composite electrode with a thermal-expansion behaviour that is well matched to that of the electrolyte. A new interphase is formed because of the limited reaction between the two materials in the composite during the calcination process, which also creates A-site deficiencies in the perovskite. As a result, the composite shows both high activity and excellent stability. The introduction of reactive negative-thermal-expansion components may provide a general strategy for the development of fully compatible and highly active electrodes for solid oxide fuel cells.
The development of clean and efficient energy conversion and storage systems is becoming increasingly vital as a result of accelerated global energy consumption. Solid oxide fuel cells (SOFCs) as one ...key class of fuel cells have attracted much attention, owing to their high energy conversion efficiency and low emissions. However, some serious problems appeared because of the scorching operating temperatures of SOFCs (800–1000 °C), such as poor thermomechanical stability and difficult sealing, resulting in a short lifespan and high cost of SOFCs. Therefore, lowering the operating temperature of SOFCs to mid-range and even low range has become one of the main goals for SOFC development in the recent years. Looking for new cathode materials with high electrocatalytic activity and robust stability at relatively low temperatures is one of the essential requirements for intermediate-to-low-temperature SOFCs (ILT-SOFCs). During the past 15 years, we put considerable efforts into the development of alternative cathode materials for ILT-SOFCs. In this review, we give a summary of our progress from such efforts. We first summarize several strategies that have been adopted for developing cathode materials with high activity and durability toward reducing operating temperatures of SOFCs. Then, our new ideas and progress on cathode development with respect to activity and stability are provided. Both the cathodes of oxygen-ion-conducting SOFCs and protonic-conducting SOFCs are discussed. In the end, we outline the opportunities, challenges, and future approaches for the development of cathodes for ILT-SOFCs.
Charcot‐Marie‐Tooth disease (CMT) is one of the most common inherited neurodegenerative disorders with an increasing number of CMT‐associated variants identified as causative factors, however, there ...has been no effective therapy for CMT to date. Aminoacyl‐tRNA synthetases (aaRS) are essential enzymes in translation by charging amino acids onto their cognate tRNAs during protein synthesis. Dominant monoallelic variants of aaRSs have been largely implicated in CMT. Some aaRSs variants affect enzymatic activity, demonstrating a loss‐of‐function property. In contrast, loss of aminoacylation activity is neither necessary nor sufficient for some aaRSs variants to cause CMT. Instead, accumulating evidence from CMT patient samples, animal genetic studies or protein conformational analysis has pinpointed toxic gain‐of‐function of aaRSs variants in CMT, suggesting complicated mechanisms underlying the pathogenesis of CMT. In this review, we summarize the latest advances in studies on CMT‐linked aaRSs, with a particular focus on their functions. The current challenges, future direction and the promising candidates for potential treatment of CMT are also discussed.
Variants of some aminoacyl‐tRNA synthetases (aaRS) are strongly associated with Charcot–Marie–Tooth disease (CMT), one of the most common inherited neuromuscular disorders. Some variants affect enzymatic activity, showing loss‐of‐function effects. In contrast, evidence from CMT patient samples, animal genetic studies or protein conformational analysis has confirmed toxic gain‐of‐function of some aaRSs variants in CMT outside of aminoacylation. In this review, we will discuss the latest advances in studies on CMT‐associated aaRSs, with a particular focus on the complicated mechanisms in the pathogenesis of CMT.
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