In this paper, we have reviewed various epoxy resins and curing agents. The properties of cured epoxy resins depend on the type of epoxy resin, curing agent, and curing process used. The toughness of ...epoxy resins can be improved by incorporating thermoplastic components, inorganics, carbon fibers, clay, and carbon nanotubes. Epoxy resins have a wide range of application including coatings, aerospace industry, electronic materials, and biomedical systems.
Epoxy resins have been widely used for coatings, electronic materials, adhesives, and matrices for fiber-reinforced composites because of their outstanding mechanical properties, high adhesion strength, good heat resistance, and high electrical resistance. The final properties of cured epoxy resins are affected by the type of epoxy resin, curing agent, and curing process. This paper aims to review the synthesis, curing process, and application of epoxy resins.
The ever‐growing demands for electrical energy storage have stimulated the pursuit of alternative advanced batteries. Zn‐ion batteries (ZIBs) are receiving increased attentions due to the low cost, ...high safety, and high eco‐efficiency. However, it is still a big challenge to develop suitable cathode materials for intercalation of Zn ions. This review provides a timely access for researchers to the recent activities regarding ZIBs. First, cathode materials including various manganese oxides, vanadium compounds, and Prussian blue analogs are summarized with details in crystal structures and Zn ion storage mechanisms. Then, the electrolytes and their influences on the electrochemical processes are discussed. Finally, opinions on the current challenge of ZIBs and perspective to future research directions are provided.
Recent advances in zinc‐ion batteries, especially the cathode materials including Mn‐based, V‐based, and Prussian blue analogs based materials, are comprehensively summarized here. The relationships between crystal structure, reaction mechanism, and electrochemical performance are elaborated.
Polymer foams have low density, good heat insulation, good sound insulation effects, high specific strength, and high corrosion resistance, and are widely used in civil and industrial applications. ...In this paper, the classification of polymer foams, principles of the foaming process, types of blowing agents, and raw materials of polymer foams are reviewed. The research progress of various foaming methods and the current problems and possible solutions are discussed in detail.
Hybrid metal‐ion capacitors (MICs) (M stands for Li or Na) are designed to deliver high energy density, rapid energy delivery, and long lifespan. The devices are composed of a battery anode and a ...supercapacitor cathode, and thus become a tradeoff between batteries and supercapacitors. In the past two decades, tremendous efforts have been put into the search for suitable electrode materials to overcome the kinetic imbalance between the battery‐type anode and the capacitor‐type cathode. Recently, some transition‐metal compounds have been found to show pseudocapacitive characteristics in a nonaqueous electrolyte, which makes them interesting high‐rate candidates for hybrid MIC anodes. Here, the material design strategies in Li‐ion and Na‐ion capacitors are summarized, with a focus on pseudocapacitive oxide anodes (Nb2O5, MoO3, etc.), which provide a new opportunity to obtain a higher power density of the hybrid devices. The application of Mxene as an anode material of MICs is also discussed. A perspective to the future research of MICs toward practical applications is proposed to close.
Hybrid metal‐ion capacitors are found to deliver high energy density and rapid energy delivery. The material design strategies particularly in pseudocapacitive oxide anodes in Li‐ion and Na‐ion capacitors (LICs and NICs) are systematically discussed. A perspective on the challenges and opportunities of LIC and NIC devices is also presented.
Epoxy resin, which is extensively used in civil and industrial applications, shows excellent comprehensive performance, especially as a polymer matrix used in fiber‐reinforced composites. A thermal ...latent initiator, used as an epoxy curing agent, has high storage stability and is widely applied in the preparation of epoxy‐based blends and fiber‐reinforced composites. In this review, the basic properties of epoxy resins and commonly used curing agents are discussed while progress on the synthesis of thermal latent initiators is reviewed in detail. Moreover, the curing mechanisms, thermal stability, and mechanical properties of epoxy resins with thermal latent initiators are also discussed.
•We present a two-dimensional (2D) Logistic-Sine-coupling map (2D-LSCM). Performance estimations demonstrate that it has better ergodicity, more complex chaotic behavior and larger chaotic range than ...several newly developed 2D chaotic maps.•Using 2D-LSCM, we further propose a 2D-LSCM-based image encryption algorithm (LSCM-IEA).•A novel permutation algorithm is designed to fast permutate image pixels while a diffusion algorithm is developed to spread little change of plain-image to the whole encrypted result.•Security analysis demonstrates that LSCM-IEA has a high security level and can outperform several advanced image encryption algorithms.
Image encryption is a straightforward strategy to protect digital images by transforming images into unrecognized ones. The chaos theory is a widely used technology for image encryption as it has many significant properties such as ergodicity and initial state sensitivity. When chaotic systems are used in image encryption, their chaos performance highly determines the security level. This paper presents a two-dimensional (2D) Logistic-Sine-coupling map (LSCM). Performance estimations demonstrate that it has better ergodicity, more complex behavior and larger chaotic range than several newly developed 2D chaotic maps. Utilizing the proposed 2D-LSCM, we further propose a 2D-LSCM-based image encryption algorithm (LSCM-IEA), which adopts the classical confusion-diffusion structure. A permutation algorithm is designed to permutate image pixels to different rows and columns while a diffusion algorithm is developed to spread few changes of plain-image to the whole encrypted result. We compare the efficiency of LSCM-IEA with several advanced algorithms and the results show that it has higher encryption efficiency. To show the superiority of LSCM-IEA, we also analyze the security of LSCM-IEA in terms of key security, ability of defending differential attack, local Shannon entropy and contrast analysis. The analysis results demonstrate that LSCM-IEA has better security performance than several existing algorithms.
Exploring highly efficient and low‐cost electrocatalysts for electrochemical water splitting is of importance for the conversion of intermediate energy. Herein, the synthesis of dual‐cation (Fe, ...Co)‐incorporated NiSe2 nanosheets (Fe, Co‐NiSe2) and systematical investigation of their electrocatalytic performance for water splitting as a function of the composition are reported. The dual‐cation incorporation can distort the lattice and induce stronger electronic interaction, leading to increased active site exposure and optimized adsorption energy of reaction intermediates compared to single‐cation‐doped or pure NiSe2. As a result, the obtained Fe0.09Co0.13‐NiSe2 porous nanosheet electrode shows an optimized catalytic activity with a low overpotential of 251 mV for oxygen evolution reaction and 92 mV for hydrogen evolution reaction (both at 10 mA cm−2 in 1 m KOH). When used as bifunctional electrodes for overall water splitting, the current density of 10 mA cm−2 is achieved at a low cell voltage of 1.52 V. This work highlights the importance of dual‐cation doping in enhancing the electrocatalyst performance of transition metal dichalcogenides.
Dual‐cation incorporation makes NiSe2 nanosheet a more effective catalyst. Introducing both Fe and Co atoms with an optimal ratio into porous NiSe2 nanosheets causes evident lattice distortion and strong electronic interaction, leading to a more efficient bifunctionality in overall electrochemical water splitting.
Our ability to efficiently process information and generate appropriate responses depends on the processes collectively called cognitive control. Despite a considerable focus in the literature on the ...cognitive control of information processing, neural mechanisms underlying control are still unclear, and have not been characterized by considering the quantity of information to be processed. A novel and comprehensive account of cognitive control is proposed using concepts from information theory, which is concerned with communication system analysis and the quantification of information. This account treats the brain as an information-processing entity where cognitive control and its underlying brain networks play a pivotal role in dealing with conditions of uncertainty. This hypothesis and theory article justifies the validity and properties of such an account and relates experimental findings to the frontoparietal network under the framework of information theory.
Esophageal cancer is one of the most fatal diseases worldwide mainly because of its rapid progression and poor prognosis. Although the incidence of esophageal adenocarcinoma has markedly risen in ...North America and Europe in the past several decades, esophageal squamous cell carcinoma is still the predominant subtype of esophageal cancer, especially in China. It accounts for more than 90% of all esophageal squamous cell carcinoma cases in China. Geographical differentiation is one of the most distinctive characteristics of esophageal cancer. The progression, risk factors, and prognosis of these two subtypes of esophageal cancer differ. This study reviews the epidemiology, etiology, and prevention of esophageal squamous cell carcinoma in China, thereby providing systematic references for policy-makers who will decide on issues of esophageal cancer prevention and control.
Organometal trihalide perovskites have recently emerged as promising materials for low‐cost, high‐efficiency solar cells. In less than five years, the efficiency of perovskite solar cells (PSC) has ...been updated rapidly as a result of new strategies adopted in their fabrication process, including device structure, interfacial engineering, chemical compositional tuning, and crystallization kinetics control. To date, the best PSC efficiency has reached 20.1%, which is close to that of single crystal silicon solar cells. However, the stability of PSC devices is still unsatisfactory and is the main bottleneck impeding their commercialization. Here, we summarize recent studies on the degradation mechanisms of organometal trihalide perovskites in PSC devices, and the strategies for stability improvement.
Organometal trihalide solar cells, despite their high efficiency and low cost, still have a serious air instability limitations. Recent studies of the degradation mechanisms of organometal trihalide perovskites in photovoltaics and various strategies for stability improvement are summarized.
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