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Abstract Nanoscale defects in two-dimensional (2D) transition metal dichalcogenides (TMDs) alter their intrinsic optical and electronic properties, and such defects require investigation. Atomic-resolution techniques such as transmission electron microscopy detect nanoscale defects accurately but are limited in terms of clarifying precise chemical and optical characteristics. In this study, we investigated nanoscale heterogeneous defects in a single-crystalline hexagonal WS2 monolayer using tip-enhanced Raman spectroscopy (TERS). We observed the Raman properties of heterogeneous defects, which are indicated by the shifted A 1′(Γ) modes appearing on the W- and S-edge domains, respectively, with defect-induced Raman (D) mode. In the edge region, various Raman features occur with nanoscale defects. In addition, the TERS signals from single-crystalline WS2 indicate the existence of two majority defects in each domain, which imply S- and W-dominated vacancies. Quantum mechanical computations were performed for each majority defect and demonstrated the defect-induced variation in the vibrational phonon modes. TERS imaging promises to be a powerful technique for determining assorted nanoscale heterogeneous defects as well as for investigating the properties of other nanomaterials.

Thermal properties, such as thermal conductivity, heat capacity, and melting temperature, influence the efficiency and stability of two-dimensional (2D) material applications. However, existing studies on thermal characteristics—except for thermal conductivity—are insufficient for 2D materials. Here, we investigated the melting temperature of 2D Tellurium (2D Te) using the nano-thermal analysis technique and found anomalous behavior that occurs before the melting temperature is reached. The theoretical calculations present surface pre-melting in 2D Te and Raman scattering measurements suggest that defects in 2D Te accelerate surface pre-melting. Understanding the pre-melting surface characteristics of 2D Te will provide valuable information for practical applications.

Focuses on a study which examined how the lifestyle of senior citizens affects their choices of retirement communities in Seoul, South Korea. Survey design; Results; Summary and conclusions.

This article aims to study the in-plane stiffness estimation of heat pipe supporter (a large lattice structure) using experimental and numerical methods. The in-plane stiffness of heat pipe supporter for nuclear power plant is very important because of the safety against natural disasters, such as seismic load or tsunami, and has to be evaluated because it greatly affects the durability of the heat exchanger. However, the modeling process of the whole lattice structure for finite element analysis increases resources needed caused by too many nodes and elements. In this study, the mechanical properties of large lattice structures are determined by a unit cell finite element analysis. The mechanical behavior of a large lattice structure has been estimated by finite element analysis through a homogenization process for reducing analysis time and efforts. The finite element analysis results have been verified and show a good agreement with the experimental results.