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Results 291-300 of 350 (Search time: 0.001 seconds).
  • 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...

  • Authors: A. Blanco; J. M. Hallen; Tu Manh, Le;  Advisor: -;  Co-Author: - (2022)

    This work presents a study on the behavior of stress corrosion cracking (SCC) phenomenon in pipeline steels for sour service in near-neutral media. SCC tests under static stressing conditions were performed in planar steel samples using a Cortest proof-ring coupled with a fabricated cell containing near-neutral pH solution as a corrosive medium, which simulates the soil conditions, to observe the cracking initiation stage. Characterizations of the steel samples using surface techniques such as SEM, EDS, and Raman spectroscopy show that the presence of nonmetallic inclusions takes place as pitting sites (to form corrosion pits), which constitute the most susceptible sites for SCC crack initiation. SEM images taken on the steel sample surfaces exhibit both SCC transgranular and interg...

  • Authors: T.H. Duong; T.-T. Le; S.X. Nguyen; M.V. Le;  Advisor: -;  Co-Author: - (2022)

    This study is devoted to the development of an Adaptive-Neuro-Fuzzy-Inference-System (ANFIS) model for the prediction of ultimate load of rectangular concrete-filled steel tubular structural members. The learning process of the model is performed by conducting a combination of backpropagation gradient descent and least-squares techniques. The performance of the model is examined by several quality metrics such as coefficient of determination (R2), Root-Mean-Squared-Error (RMSE), Mean-Absolute-Error (MAE), Index of Agreement (IA) and Slope of linear regression. Monte Carlo random sampling technique is employed to propagate input variations to the output response. Moreover, the performance of ANFIS is also compared with other machine learning models including Artificial Neural Network...

  • Authors: Abdullah H. Alshehr; Jhi Yong Loke; Viet Huong Nguyen; Alexander Jones; Hatameh Asgarimoghaddam; Louis-Vincent Delumeau; Ahmed Shahin; Khaled H. Ibrahim; Kissan Mistry; Mustafa Yavuz; David Mu�oz-Rojas; Kevin P. Musselman;  Advisor: -;  Co-Author: - (2021)

    Nanoscale films are integral to all modern electronics. To optimize device performance, researchers vary the film thickness by making batches of devices, which is time-consuming and produces experimental artifacts. Thin films with nanoscale thickness gradients that are rapidly deposited in open air for combinatorial and high-throughput (CHT) studies are presented. Atmospheric pressure spatial atomic layer deposition reactor heads are used to produce spatially varying chemical vapor deposition rates on the order of angstroms per second. ZnO and Al2O3 films are printed with nm-scale thickness gradients in as little as 45 s and CHT analysis of a metal-insulator-metal diode and perovskite solar cell is performed. By testing 360 Pt/Al2O3/Al diodes with 18 different Al2O3 thicknesses on o...

  • Authors: Quan-Hoang Vuong; Minh-Hoang Nguyen; Tam-Tri Le;  Advisor: -;  Co-Author: - (2021)

    Although studies have explored the predictors of book reading interest among children, little is known about the underlying mechanism that helps children become interested in reading books. This study attempt to demonstrate: (1) how book-reading interest is driven by reasons for choosing books (recommendation or personal preference), (2) how students with high and low academic achievements are motivated by different thinking pathways, and (3) how home scholarly culture improves book-reading interest through such pathways. Using Bayesian analysis on a dataset of survey responses from 4966 Vietnamese secondary students (11–15 years old, sixth to ninth grade), we found: (i) Reading interest is positively associated with a book recommendation and parental book reading activities (parent...