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Results 421-430 of 691 (Search time: 0.001 seconds).
  • Authors: Minhhuy Le;  Advisor: Van Su Luong; Khoa Dang Nguyen; Jinyi Lee;  Co-Author: - (2021)

    Detection of corrosion at rivet sites in a multilayer structure of an aircraft is an essential task to ensure the flight safety of an aircraft. It is challenging to detect the corrosion due to the influence on the signal of the rivet and the multiple fastened layers in the structure. In this letter, an electromagnetic testing method is used in conjunction with principal component analysis (PCA) to detect corrosion around fasteners. Multiple Hall sensors were used for efficient measurement of the magnetic field distribution at the rivet sites. The features of the scanned magnetic image were automatically extracted by the PCA in orthogonal subspaces. The proposed method shows potential results of features extraction and corrosion signal extraction for further development of electromag...

  • Authors: Minh Cuong, Duong; Hong Trang, Nguyen; Mai, Duong;  Advisor: -;  Co-Author: - (2022)

    Vaccine hesitancy is a major threat to COVID-19 vaccination programs. This study aimed to examine the public attitudes towards COVID-19 vaccines, the variance of these attitudes, and associated determinants within a large COVID-19 outbreak in Vietnam.

  • Authors: Quoc, Thai Cao; Quan, Hoang Vuong; Hiep, Hung Pham; ; Dinh, Hai Luong; Manh, Toan Ho; Anh, Duc Hoang; Minh, Trang Do;  Advisor: -;  Co-Author: - (2021)

    The mental health of university students is not only a predominant topic for psychology and education researchers but also a source of interest for policymakers and various stakeholders. Although there has been a lot of research on higher education students’ mental health, we have little understanding on the mental health of international students (MHIS). Despite their distinctive characteristics compared to native students, the mental health issues of international students only started receiving attention very recently. So far, the literature on this topic lacks a comprehensive overview of its sub-topic and trending issues. By using bibliometric analysis, this research aims to fulfil this gap and provide a review of the extant literature about MHIS. Specifically, this study aims t...

  • Authors: Van Tan, Tran; Jeonghyo, Kim; Sangjin, Oh; Ki-Jae Jeong; Jaebeom, Lee;  Advisor: -;  Co-Author: - (2022)

    There are usually trade-offs between maximizing the color saturation and brightness and minimizing the angle-dependent effect in structural colors. Here, a magnetic field-induced assembly for the rapid formation of scalable, uniform amorphous photonic arrays (APAs) featuring unique structural colors is demonstrated. The magnetic field plays a fundamental role in photonic film formation, making this assembly technology versatile for developing structural color patterns on arbitrary substrates. The synergistic combination of surface plasmonic resonance of the Ag core and broadband light absorption of high refractive index (RI) Fe3O4 shell in hybrid magnetoplasmonic nanoparticles (MagPlas NPs) enables breaking the trade-offs to produce brilliant, noniridescent structural colors with hi...

  • Authors: Kenny, Kuchta; Kosuke, Aritake; Yoshihiro, Urade;  Advisor: -;  Co-Author: - (2022)

    The objective of this review is to evaluate the anti-dementia activities of saffron and its combination with Kampo medicine. The Kampo formula Kamiuntanto composed of 13 crude drugs is well known for its anti-dementia activity. A significant increase in choline acetyltransferase activity and mRNA levels were observed. Polygala radix was identified as the most essential component drug in Kamiuntanto, probably due to the saponins, tenuifolin, and sinapinic acid. Ginseng was also identified as an essential Kamiuntanto component in terms of its synergistic functions with Polygala radix. Saffron, which was recommended in the Bencao Gangmu for memory and dementia, and is used as an anti-spasmodic, anti-catarrhal, and sedative herbal drug. Saffron and its major constituent, crocin were sho...

  • Authors: Vinh, V.Le; Dinh, Thi Hinh;  Advisor: -;  Co-Author: - (2022)

    The molecular dynamics simulations have been carried out to investigate the mechanical behaviors of amorphous silicon nitride under the uniaxial tensile deformation. The amorphous silicon nitride was obtained by the cooling process. The network structure of the sample consists of SiNx (x = 3, 4 and 5) units and NSiy (y = 2, 3 and 4) linkages. The stress-strain curve of the sample exhibits the elastic and plastic deformation. The Si-N bond lengths are stretched out in the elastic region and the plastic region I. They are shrunk to the initial state in the plastic region II due to the appearance of the large clusters which contain the overlapping big simplexes with the RS ≥ 2.4 Å. These big simplexes tend to appear at the shear transformation zones in the elastic region. These shear t...

  • Authors: Tran, Dinh Cuong; Anh D. Phan;  Advisor: -;  Co-Author: - (2022)

    Vacancies are prevalent point defects in crystals, but their thermal responses are elusive. Herein, we formulate a simple theoretical model to shed light on the vacancy evolution during heating. Vibrational excitations are thoroughly investigated via moment recurrence techniques in quantum statistical mechanics. On that basis, we carry out numerical analyses for Ag, Cu, and Ni with the Sutton–Chen many-body potential. Our results reveal that the well-known Arrhenius law is insufficient to describe the proliferation of vacancies. Specifically, anharmonic effects lead to a strong nonlinearity in the Gibbs energy of vacancy formation. Our physical picture is well supported by previous simulations and experiments.

  • Authors: Nguyen, Le Nhat Trang; Dao, Thi Nguyet Nga; Van-Tuan Hoang; Xuan-Dinh Ngo; Pham, Tuyet Nhung; Anh-Tuan Le;  Advisor: -;  Co-Author: - (2022)

    The present work reports efficient electrochemical nanosensors for the sensitive monitoring of 4-nitrophenol (4-NP) in tomato samples using various biosynthesized silver nanoparticles (bio-AgNPs). Three different bio-AgNP types were synthesized using natural plant extracts, including green tea (GT) leaf, grapefruit peel (GP), and mangosteen peel (MP), aiming to investigate their effects on the formation of bio-AgNPs, as well as the analytical performance of 4-NP. Based on the obtained results, it was found that the phytochemical content in various plant extracts directly influenced the physicochemical parameters of the created bio-AgNPs, such as particle size, crystallinity, and distribution. More importantly, these parameters have decisive effects on the electrocatalytic activity, ...

  • Authors: M.T.Tran; N.V.Du; N.Tu;  Advisor: -;  Co-Author: - (2022)

    ZnS has great potential as a valuable material for nanoscale devices because of its rich morphologies and unique structure. Although much effort has been made, the growth of high-quality ZnS crystal is still a challenge. In this paper, high-quality optically defect-free 1D ZnS nanostructures, including nanorods, nanowires, and nanobelts, were successfully synthesized on a large scale by a modified thermal evaporation method. XRD patterns and HRTEM images indicated that the ZnS nanostructures are single phases with hexagonal structures. Under optical excitation, all the ZnS nanostructures show intense UV emissions and almost no defect emissions at room temperature. Sharp UV lasing-like peaks with the FWHM as narrow as 2–3 nm are achieved for the ZnS nanobelts and nanowires. The optic...