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CePO4:Tb Nanoparticles: Preparation, Structure and Optical Properties
Nguyen Vu Thanh,Tran Kim Anh,Nguyen Quang Liem,Nguyen Huu Quan,Nguyen The Khoi 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5
Nanocrystals of CePO4:Tb were prepared by reacting the corresponding metal chlorides, phos- phoric acid and trioctylamine at 200℃ in tris(2-ethylhexyl) phosphate (TEHP). The samples were characterized by X-ray diffraction and scanning electron microscopy (SEM). The photoluminescence (PL) and the absorption spectra of CePO4:Tb nanoparticles will be presented. The PL spectra are described by using the well-known 5D4 - 7FJ transitions (J = 6, 5, 4, 3 ···) of Tb3+ ions with the strongest emission at 543 nm for J = 5. The dependence of PL intensity on Tb3+ concentration has been investigated. Nanocrystals of CePO4:Tb were prepared by reacting the corresponding metal chlorides, phos- phoric acid and trioctylamine at 200℃ in tris(2-ethylhexyl) phosphate (TEHP). The samples were characterized by X-ray diffraction and scanning electron microscopy (SEM). The photoluminescence (PL) and the absorption spectra of CePO4:Tb nanoparticles will be presented. The PL spectra are described by using the well-known 5D4 - 7FJ transitions (J = 6, 5, 4, 3 ···) of Tb3+ ions with the strongest emission at 543 nm for J = 5. The dependence of PL intensity on Tb3+ concentration has been investigated.
Van-Anh Nguyen,Huy L. Nguyen,Dzung T. Nguyen,Quan P. Do,Lam D. Tran 한국물리학회 2017 Current Applied Physics Vol.17 No.11
In this paper, an electrosynthesized bilayer film of polypyrrole nanowire and poly(1,5- diaminonaphthalene) on a disposable screen-printing carbon ink electrode is presented. The inner polypyrrole nanowire layer had a large surface-to-volume ratio and high conductivity in the neutral medium, whereas the outer layer of poly(1,5diaminonaphthalene) had functional amino groups on the polymer chains. The combination of polypyrrole nanowire and poly(1,5diaminonaphthalene) showed a promising material for electrochemical biosensing. Here we reported an electrochemical immunosensor based on this approach for the purpose of detecting breast cancer biomarkers. The bilayer could enhance the surface coverage of antibody anti-CA 15-3 and consequently improve the sensitivity and stability of the immunosensors. The magnetic beads were used as carriers of labeled antibody anti-CA15-3 and HRP (horseradish peroxidase) in order to achieve an amplification of the signal. Under optimized conditions, the linear range of the immunoassay was 0.05e20 U mL1 with a detection limit of 0.02 U mL1 CA 15-3 antigen.
Required Base Station Density for Communication-Efficient Federated Learning in Small-Cell Networks
Khoa Anh Nguyen,Quan Anh Nguyen,Jun-Pyo Hong 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6
Federated Learning (FL) generates massive benefits of shared machine learning models without violating security and privacy requirements, making this setting relevant for many wireless applications. In this paper, we comprehensively investigate the effects of geographic node deployment on the model aggregation in federated learning on the basis of stochastic geometry-based analysis. Based on the coverage probability expression derived with stochastic geometry framework, we derive and discuss the minimum required base station density for achieving a target model aggregation rate in small-cell networks with algorithms for optimizing the target transmission rate and the base station density.
Phan Thi Anh Dao,Nguyen Xuan Hai,Nguyen Trung Nhan,Tran Le Quan,Nguyen Thi Thanh Mai 한국생약학회 2012 Natural Product Sciences Vol.18 No.1
Among 90 Vietnamese medicinal plant extracts investigated for their antioxidant activity by DPPH assay at various concentrations from 10 - 100 ?g/mL, 67 showed an inhibition rate over 50% at 100 ?g/mL; 47 had greater than 50% inhibition at 50 ?g/mL; 17 showed over 50% inhibition at 25 ?g/mL. 8 extracts which exhibited strong inhibitory activity more than 50% inhibition at 10 ?g/mL were further tested for lipid peroxidation inhibition by TBA assay. They displayed activity with IC50 values from 30.6 to 158.9 ?g/mL. Until now, this is the first report on antioxidant activity of the female flower of Borassus flabellifer, and the stem of Combretum latifolium, Embelia ribes, Spatholobus parviflorus, and Tetrastigma erubescens. Fractionations of the EtOAc extract prepared from S. parviflorus led to the isolation of protocatechuic acid (1), ferulic acid (2), epicatechin (3), and gallic acid (4). These compounds showed significant DPPH inhibitory activity with IC50 values from 6.5 to 23.6 ?M.
Thu Ha Nguyen,Thi Lan Pham,Anh Quan Cao,Tuan Anh Nguyen,Xuan Minh Vu,Thi My Hanh Le,Van Thuan Le,Seiichi Kawahara,Dai Lam Tran 한국고분자학회 2024 Macromolecular Research Vol.32 No.4
This study describes the preparation and characterization of a green and safe membrane based on a natural polymer for metal adsorption. Natural rubber-grafted-(2-hydroxyethyl methacrylate) with a special nanostructure was synthesized by graft copolymerization of 2-hydroxyethyl methacrylate (HEMA) onto the surface of natural rubber (NR) particles using tert-butylhydroperoxide/tetraethylenepentamine as initiators. Optimal conditions for achieving high conversion and grafting efficiency were identified. Characterization of the as-synthesized samples was performed using Fourier-transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, tensile measurement, swelling degree determination, and cytotoxicity testing. The results revealed that HEMA formed a nanoscale matrix surrounding NR particles, which improved the tensile strength, thermal resistance, and swelling degree of the as-prepared samples. Cytotoxicity testing demonstrated that the membrane was safe for human use, as it did not exhibit toxicity to Vero cells at concentrations up to 1024 μg/mL. Furthermore, the membrane displayed a high adsorption capacity toward Fe3+ and was well described by Koble-Corrigan isotherm model and the first–second-order kinetic equation. Moreover, the membrane demonstrated excellent recyclability maintaining its adsorption ability towards Fe3+ ions over five consecutive cycles. Overall, these findings may recommend the NR-HEMA membrane as a promising candidate for metal removal applications.
Dieu Linh Tran,Anh Phuong Nguyen Hong,Ngoc Hoi Nguyen,Ngoc Trinh Huynh,Bao Ha Le Tran,Cam Tu Tran,Minh Dung Truong,Quan Dang Nguyen,박기동,Dai Hai Nguyen 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-
α-calcium sulfate hemihydrate (α-HH) was synthesized by salt solution methods to prepare a promising biomaterial for bone tissue repair and regeneration. The successful synthesis of α-HH was evaluated by field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) scanning. The sterility of α-HH before and after irradiation with gamma ray was firstly confirmed by Colonies Forming Units (CFU) counting assay, to target the surgical grade application. In vitro tetrazolium bromide (MTT) assay, crystal violet (CV) and acridine orange (AO) staining was performed to assess the initial cytotoxicity and cell attachment ability of α-HH. Further in vivo implantation into rabbit distal femoral condyles defect exhibited the ability of salt solution-synthesized α-HH to promote the localization of osteocytes and osteoblasts, which improve the bone tissue repair and regeneration. The findings suggested that α-calcium sulfate hemihydrate synthesized by salt solution method is a potential material that can be used as bone substitutes.
Quan T. Lai,Vu Anh Tuan,Dinh Kim Dieu,Alexander B. Orfinger,Ngo Minh Ly,Nguyen Thanh Ha,Trinh Truong Giang 한국해양과학기술원 2022 Ocean science journal Vol.57 No.4
This study aimed to analyze the sex ratio, spawning seasons, length at first maturity, length distribution, length–weight relationship, and relative condition factor of Cultellus maximus (Gmelin, 1791) in Southern Vietnam. A total of 1037 individuals of C. maximus were collected at 3 sampling sites from June, 2019 to June, 2020. The sex ratio was found to be female biased in Can Gio and male biased in Phu Tan and Ngoc Hien. The clam spawns throughout the year, peaking at Q2 and Q3 during the rainy season. Pooled length at first maturity was 10.12 cm (9.65–10.49 cm CI 95%, P-value < 2.2·10–16). The length–weight relationship indicates positive allometric growth. This study suggests that imposing a minimum harvest size limit on C. maximus using the length at first maturity as reference and with harvest seasons in Q1 in Ngoc Hien and Can Gio and Q2 or Q3 in Phu Tan would be ideal for consumption of this species.
The Study of Mach Waves Generated by a Roughness Element
Hoang Quan Dinh,Anh Tuan Nguyen,Ivan Vladimirovich Egorov,Ngoc Hai Duong 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.3
In this paper, a simplified inviscid boundary condition is applied to solve the problem of Mach waves generated by a roughness element on the wall surface of a supersonic wind tunnel. The geometry of the roughness element is simplified by a parabolic function, to which mathematical formulas are introduced to model the boundary condition. These techniques help simplify the problem and minimize the required computer resources for the simulation performance. Using the direct numerical simulation (DNS) method while employing the above-mentioned techniques, the authors can simulate the generation and the propagation of Mach waves from a roughness element at a Mach number of 2.5. The result shows that a pair of Mach waves are generated at the leading and trailing edges of the roughness element and oscillate with small amplitudes. We also study the effect of the height of the element, the flow speed, the Reynolds number, and the unsteadiness of the flow on the simulation result. The numerical result is compared with published experimental data for the validation.
Nonlinear dynamic response and vibration of nanocomposite multilayer organic solar cell
Duc, Nguyen Dinh,Seung-Eock, Kim,Quan, Tran Quoc,Long, Dang Dinh,Anh, Vu Minh Elsevier 2018 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.184 No.-
<P><B>Abstract</B></P> <P>In the recent years, organic solar cell (OSC) has attracted much interest of the research community due to its great promise as renewable sources. This paper presents the first analytical approach to investigate the nonlinear dynamic response and vibration of imperfect rectangular nanocompsite multilayer organic solar cell subjected to mechanical loads using the classical plate theory. Nanocompsite organic solar cell consists of five layers of Al, P3HT:PCBM, PEDOT:PSS, IOT and glass. Motion and compatibility equations are derived using the classical plate theory and taking into account the effects of initial geometrical imperfection and geometrical nonlinearity in Von Karman – Donnell sense. The Galerkin method and fourth – order Runge – Kutta method are used to give explicit expressions of natural frequencies, nonlinear frequency – amplitude relation and nonlinear dynamic responses of nanocompsite organic solar cell. The numerical results show the influences of geometrical parameters, the thickness of layers, imperfections, and mechanical loads on the nonlinear dynamic response and nonlinear vibration of nanocompsite organic solar cell.</P>