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[Purpose/Significance] This paper aims to explore whether there are differences in the title and abstract, citation content, and full-text content on research topic, and analyze whether the topic content in the title and abstract can reveal the research content of the full text and the effect of the citation content on the content of the citing literature, so as to provide theoretical support for analyzing the research content of the full text based on the title and abstract of the literature. [Method/Process] This paper conducts an empirical study using Chinese journal papers in the field of COVID-19, extracts feature words from the titles and abstracts, citations and full-text contents of the literature, uses the clustering algorithm to cluster the feature words, and then uses manual interpretation to identify the research topics, and conducts a comparative study to analyze the topic differences among the three parts. [Results/Conclusions] The results show that: the research topics are different in the title and abstract, citation content and full-text content of the literature; compared with the title and abstract, the full text contains more topic content, but the difference in the topic content is small, so the topic content in the title and abstract can be used to represent the research content of the full text; the content of the citation is related to the topic of the citing literature, and they can complement each other.

High theoretical capacity, stabilized and layered 2H phase molybdenum disulfide (2H) is regarded as a promising material for superior kinetics anode in sodium ion battery, but the inherent semiconducting properties and sluggish sodium ions diffusion limit the development of 2H based anode. Hence, this study builds a unique metalloid phase with high electronic conductivity and suitable layer structure by screening non‐metallic carbon atoms doped in 2H (2H‐C). As experimental and simulation results, 2H‐C of metalloid properties after carbon atom modulation exhibit superior sodium storage kinetics and reversibility by a unique mechanism that promotes ion intercalation under high voltage window, and further good for the later uniformly conversion at lower voltage (intercalation‐conversion mechanism). The 2H‐C anode material delivers a remarkable reversible capacity of 156 mAh g−1 at ultra‐high 100.0 A g−1, long‐term life of 6000 cycles, and superior performance at low temperatures of −10 °C. Otherwise, 2H‐C/Na3V2(PO4)3 full cell also performs charge/discharge capacity of 80.0/76.7 mAh g−1 with 87% capacity retention after 140 cycles at 0 °C. This discovery further explores the unique mechanism and application of 2D layered materials in sodium‐ion battery anodes for fast kinetics under extreme conditions. [ABSTRACT FROM AUTHOR]

We report on 2-dimensional electron gases realized in binary N-polar GaN channels on AlN on sapphire templates grown by metal–organic vapor phase epitaxy. The measured sheet carrier density of 3.8 × 10 13 cm−2 is very close to the theoretical value of 3.95 × 10 13 cm−2 due to the low carbon and oxygen background doping in the N-polar GaN if grown with triethyl-gallium. By inserting an intermediate AlN transition layer, room temperature mobilities in 5 nm channels up to 100 cm2/Vs were realized, probably limited by dislocations and oxygen background in N-polar AlN. Thicker channels of 8 nm or more showed relaxation and thus much lower mobilities. [ABSTRACT FROM AUTHOR]

Constructing a heterojunction is an effective way to overcome the handicaps of single-component photocatalysts for the photocatalytic N2 reduction reaction (PNRR). However, the fundamental photophysical processes between two semiconductors with different nanostructures are still unclear. Drawing upon a combination of experimental observations and theoretical calculations, a series of binary nanohybrid photocatalysts of MoS2 (nanodot, monolayer, and few nanolayers) and carbon nitride are systematically evaluated as potential N2 reduction reaction photocatalysts. Owing to the atomically well-defined interfacial interaction between MoS2 and graphitic carbon nitride (GCN), charge accumulates in MoS2. Meanwhile, the electron density of MoS2 increases with the reduction of nanosize, thereby facilitating N2 adsorption on the Mo-edge and boosting the potential-determining step of the desorption of the NH3 molecule. Simultaneously, the MoS2 nanodot anchored on GCN manifests a compelling photothermal effect upon solar light irradiation and raises the temperature of the compound in situ, leading to efficient charge transfer and thereby enhancing the photocatalytic performance. Encouragingly, the final product reaches a high ammonia synthesis rate of 2.71 mmol h–1 g–1 at ambient conditions and an apparent quantum of 0.62% at 430 nm. Establishing the relationship between the nano-, electronic structure and PNRR performance of MoS2/GCN heterojunction materials provides valuable insights for their potential application in PNRR technology. [ABSTRACT FROM AUTHOR]

Ethereum smart contracts are programs that can be collectively executed by a network of mutually untrusted nodes. Smart contracts handle and transfer assets of values, offering strong incentives for malicious attacks. Intrusion attacks are a popular type of malicious attacks. ContractGuard, the first intrusion detection system (IDS) was proposed to defend Ethereum smart contracts against such attacks. Like IDSs for conventional programs, ContractGuard detects intrusion attempts as abnormal control flow. However, existing IDS techniques or tools are inapplicable to Ethereum smart contracts due to Ethereum’s decentralized nature and its highly restrictive execution environment. To address these issues, ContractGuard was designed by embedding it in the contracts. At runtime, ContractGuard protects the smart contract by monitoring the context-tagged acyclic path of the smart contract. As ContractGuard involves deployment overhead and deployment overhead. It was optimized under the Ethereum Gas-oriented performance model to reduce the overheads. The experimental results show that this work can effectively detect 83% of vulnerabilities, ContractGuard only adds to 36.14% of the deployment overhead and 28.27% of the runtime overhead.

The microstructure and texture evolution of Cu-Ni-P alloy after cold rolling and annealing at 500 °C was studied by electron backscattering diffraction (EBSD). The equiaxed grain is elongated and the dislocation density increases gradually after cold rolling. The grain boundaries become blurred and the structure becomes banded when the reduction in cold rolling reaches 95%. A typical rolling texture is formed with the increase in deformation amount in cold rolling. The deformation structure gradually disappeared and recrystallized new grains were formed after annealing at 500 °C. The recrystallization nucleation mechanism of Cu-Ni-P alloy at 60% reduction is mainly a bow nucleation mechanism. A shear band begins to form after annealing at 80% reduction. The shear band becomes the preferred nucleation location with the increase in reduction. Most adjacent recrystallized grains growing in the shear band have a twin relationship. [ABSTRACT FROM AUTHOR]

Metal sulfides have been regarded as highly competitive anode materials for fast sodium storage due to their excellent redox reversibility and comparatively great electron properties. Nevertheless, metal sulfides suffer from serious structure collapse and capacity attenuation during fast cycling. Herein, the iron-based sulfide polycrystalline phase material grown in situ on hollow carbon nanofibers was synthesized (NHCFs-Fe7S8/FeS2). The construction of the polycrystalline phase is an effective strategy to enhance electron and ion transport, and improve the reaction kinetics of sodium ions. Meanwhile, the construction of a carbon network can effectively alleviate the volume expansion in the process of fast charge/discharge and maintain the stability of the structure. Thanks to these unique characteristics, NHCFs-Fe7S8/FeS2 exhibits a significantly enhanced electrochemical performance, which reveals outstanding long-term cycling stability (595.7 mA h g−1 at 1.0 A g−1 after 1000 cycles) and rate properties (154.7 mA h g−1 at 50.0 A g−1 and 107.0 mA h g−1 at 100.0 A g−1). The structure decoration method of metal sulfides can provide effective guidance for the design of other high-performance electrode materials for fast-charging sodium-ion batteries. [ABSTRACT FROM AUTHOR]