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11.
Yan He Kangren Kong Zhengxi Guo Weifeng Fang Zaiqiang Ma Haihua Pan Ruikang Tang Zhaoming Liu 《Advanced functional materials》2021,31(26):2101291
Sensitivity and multi-directional motivation are major two factors for developing optimized humidity-response materials, which are promising for sensing, energy production, etc. Organic functional groups are commonly used as the water sensitive units through hydrogen bond interactions with water molecules in actuators. The multi-coordination ability of inorganic ions implies that the inorganic ionic compounds are potentially superior water sensitive units. However, the particle forms of inorganic ionic compounds produced by classical nucleation limit the number of exposed ions to interact with water. Recent progress on the inorganic ionic oligomers has broken through the limitation of classical nucleation, and realized the molecular-scaled incorporation of inorganic ionic compounds into an organic matrix. Here, the incorporation of hydrophilic calcium carbonate ionic oligomers into hydrophobic poly(vinylidene fluoride) (PVDF) is demonstrated. The ultra-small calcium carbonate oligomers within a PVDF film endow it with an ultra-sensitive, reversible, and bidirectional response. The motivation ability is superior to other bidirectional humidity-actuators at present, which realizes self-motivation on an ice surface, converting the chemical potential energy of the humidity gradient from ice to kinetic energy. 相似文献
12.
Bin Feng Xin Jiang Guisheng Zou Wengan Wang Tianming Sun Heng Yang Guanlei Zhao Mingye Dong Yu Xiao Hongwei Zhu Lei Liu 《Advanced functional materials》2021,31(29):2102359
The realization of liquid metal-based wearable systems will be a milestone toward high-performance, integrated electronic skin. However, despite the revolutionary progress achieved in many other components of electronic skin, liquid metal-based flexible sensors still suffer from poor sensitivity due to the insufficient resistance change of liquid metal to deformation. Herein, a nacre-inspired architecture composed of a biphasic pattern (liquid metal with Cr/Cu underlayer) as “bricks” and strain-sensitive Ag film as “mortar” is developed, which breaks the long-standing sensitivity bottleneck of liquid metal-based electronic skin. With 2 orders of magnitude of sensitivity amplification while maintaining wide (>85%) working range, for the first time, liquid metal-based strain sensors rival the state-of-art counterparts. This liquid metal composite features spatially regulated cracking behavior. On the one hand, hard Cr cells locally modulate the strain distribution, which avoids premature cut-through cracks and prolongs the defect propagation in the adjacent Ag film. On the other hand, the separated liquid metal cells prevent unfavorable continuous liquid-metal paths and create crack-free regions during strain. Demonstrated in diverse scenarios, the proposed design concept may spark more applications of ultrasensitive liquid metal-based electronic skins, and reveals a pathway for sensor development via crack engineering. 相似文献
13.
The luminescent hydrogen-bonded organic framework (HOF) based films have become one of the most remarkable materials for optical application, thus, developing facile synthesis methods and establishing multifunctional applications for HOF-based luminescent materials are essential. Herein, a dual-emitting Eu3+-functionalized HOF hydrogel film ( 1 ) is fabricated successfully. 1 emits a blue-green long afterglow when turning off the UV lamp, and the long afterglow lifetime gets to 1.99 s. 1 performs great selectivity, high sensitivity, and low detection limit toward ofloxacin and flumequine, and the sensing toward ofloxacin and flumequine is in accord with the chroma and ratio modes. The fluorescent response mechanisms of 1 toward ofloxacin and flumequine are investigated in depth, which are further utilized to build an anticounterfeiting platform with high-level security. The film-based anticounterfeiting platform can conduct information encryption on demand inline with different fluorescent responses and can also fetch specific information by controlling the long afterglow intensity and excited light. This study not only provides a representative case of the fabrication of dual-emitting Eu3+-functionalized HOF-based hydrogel film but also opens the possibility of HOF-based film as intelligent luminescent materials with multifunctionalities. 相似文献
14.
Yueqiang LI Chao GAO Bin WU Yushuai WANG Haibo ZHENG Ming XUE Yuling WANG 《等离子体科学和技术》2021,23(2):25501-37
The turbulent boundary layer control on NACA 0012 airfoil with Mach number ranging from 0.3 to 0.5 by a spanwise array of dielectric barrier discharge(DBD)plasma actuators by hot-film sensor technology is investigated.Due to temperature change mainly caused through heat produced along with plasma will lead to measurement error of shear stress measured by hot-film sensor,the correction method that takes account of the change measured by another sensor is used and works well.In order to achieve the value of shear stress change,we combine computational fluid dynamics computation with experiment to calibrate the hot-film sensor.To test the stability of the hot-film sensor,seven repeated measurements of shear stress at Ma = 0.3 are conducted and show that confidence interval of hot-film sensor measurement is from-0.18 to 0.18 Pa and the root mean square is 0.11 Pa giving a relative error 0.5%over all Mach numbers in this experiment.The research on the turbulent boundary layer control with DBD plasma actuators demonstrates that the control makes shear stress increase by about 6%over the three Mach numbers,which is thought to be reliable through comparing it with the relative error 0.5%,and the value is hardly affected by burst frequency and excitation voltage. 相似文献
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18.
徐滨 《河南工程学院学报(自然科学版)》2021,33(1):59-61,69
车桥半轴齿轮是差速器的重要组成部分,在差速器工作中扮演着十分重要的角色.针对断裂的半轴齿轮进行断口形貌、成分及硬度分析,并结合有限元模拟分析齿轮失效的原因.结果表明:齿轮渗碳层厚度约0.8 mm,渗碳层显微组织主要为硬度较高的针状马氏体和部分残留奥氏体,硬度达785.1 N/mm2,表面硬化处理与渗碳处理基本符合工况要求.通过ABAQUS模拟发现半轴齿轮最易断裂处位于齿根最靠近边角的部位,与实际工况吻合. 相似文献
19.
In this study, a kind of Ni-based superalloy specially designed for additive manufacturing (AM) was investigated. Thermo-Calc simulation and differential scanning calorimetry (DSC) analysis were used to determine phases and their transformation temperature. Experimental specimens were prepared by laser metal deposition (LMD) and traditional casting method. Microstructure, phase constitution and mechanical properties of the alloy were characterized by scanning electron microscopy (SEM), transmission scanning electron microscopy (TEM), X-ray diffraction (XRD) and tensile tests. The results show that this alloy contains two basic phases, γ/γ', in addition to these phases, at least two secondary phases may be present, such as MC carbides and Laves phases. Furthermore, the as-deposited alloy has finer dendrite, its mean primary dendrite arm space (PDAS) is about 30-45 μm, and the average size of γ' particles is 100-150 nm. However, the dendrite size of the as-cast alloy is much larger and its PDAS is 300-500 μm with secondary and even third dendrite arms. Correspondingly, the alloy displays different tensile behavior with different processing methods, and the as-deposited specimen shows better ultimate tensile stress (1,085.7±51.7 MPa), yield stress (697±19.5 MPa) and elongation (25.8%±2.2%) than that of the as-cast specimen. The differences in mechanical properties of the alloy are due to the different morphology and size of dendrites, γ', and Laves phase, and the segregation of elements, etc. Such important information would be helpful for alloy application as well as new alloy development. 相似文献
20.
Bone related diseases have caused serious threats to human health owing to their complexity and specificity. Fortunately, owing to the unique 3D network structure with high aqueous content and functional properties, emerging hydrogels are regarded as one of the most promising candidates for bone tissue engineering, such as repairing cartilage injury, skull defect, and arthritis. Herein, various design strategies and synthesis methods (e.g., 3D-printing technology and nanoparticle composite strategy) are introduced to prepare implanted hydrogel scaffolds with tunable mechanical strength, favorable biocompatibility, and excellent bioactivity for applying in bone regeneration. Injectable hydrogels based on biocompatible materials (e.g., collagen, hyaluronic acid, chitosan, polyethylene glycol, etc.) possess many advantages in minimally invasive surgery, including adjustable physicochemical properties, filling irregular shapes of defect sites, and on-demand release drugs or growth factors in response to different stimuli (e.g., pH, temperature, redox, enzyme, light, magnetic, etc.). In addition, drug delivery systems based on micro/nanogels are discussed, and its numerous promising designs used in the application of bone diseases (e.g., rheumatoid arthritis, osteoarthritis, cartilage defect) are also briefed in this review. Particularly, several key factors of hydrogel scaffolds (e.g., mechanical property, pore size, and release behavior of active factors) that can induce bone tissue regeneration are also summarized in this review. It is anticipated that advanced approaches and innovative ideas of bioactive hydrogels will be exploited in the clinical field and increase the life quality of patients with the bone injury. 相似文献