Collection's Items (Sorted by Submit Date in Descending order): 1 to 20 of 621
- Journal Article
Authors: Luong, Van Tung; Nguyen, Quang Bau; Tran, Ngoc Bich; Pham, Tuan Vinh; Huynh, Vinh Phuc (2021) - This work studies the linear, the third-order nonlinear, and the total optical absorption
coefficients (OACs) and the refractive index changes (RICs) caused by both intra- and inter-band
transitions in the WSe2 monolayer. The expression for the OACs and RICs in the presence of a
magnetic field as well as the Zeeman and electric fields are found by using the compact density
matrix approach. The results show that the spin states strongly affect the OACs and RICs, which
display the violet-shift behavior with the increase of the magnetic field. The Zeeman fields do not
affect the peak positions but slightly reduce peak intensities. The OACs and RICs due to intra-band
transit...
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- Journal Article
Authors: Hoang, Ngoc Long; Vo, Van Vien; Vu, Hoa Binh (2021) - The one-loop contribution axion-photon-photon coupling is presented in the framework
of the 3-3-1 model, in which the loop diagrams are finite. The decay of axion into two photons is
demonstrated. This study shows that it is easy to fulfill dark matter candidate conditions for the
axion in the model
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- Journal Article
Authors: Luong, Hoai Nhan; Nguyen, Huu Khoa; Lai, Thi Ngoc Huyen; Huynh, Hung Quang; Dinh, Tan Muon; Nguyen, Ngoc Phuong; Tran, Cong Khanh; Phan, Bach Thang; Dang, Vinh Quang (2021) - ZnO is a promising photocatalyst for photocatalytic oxidation of organic compounds
under the influence of sunlight that provides clean energy and decomposes sustainable organic
pollutants substances. ZnO is found to have non-toxic properties, long-term stability, high carrier
mobility, low cost and biocompatibility. However, some disadvantages of ZnO limit its use in
photocatalysis. Due to its wide bandgap, ZnO can only be activated under UV illumination. On the
other hand, the photo-excited electron-hole pairs that recombine quickly on ZnO surface, suppress
its photocatalytic properties. To improve its properties and performance, doping with transition
metals was used to...
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Authors: Mai, Thi Lan; Nguyen, Thu Nhan; Nguyen, Thi Thao; Pham, Tri Dung (2021) - This work presents the effect of pressure on the local microstructure of amorphous
Germania (GeO2). The Molecular Dynamics simulation was performed on systems at 900 K and
high pressure up to 70 GPa. The structural properties have been analyzed through the pair correlation
function, coordination number distribution, and structure factors. The structural phase transition
process starts occurring at 30 GPa. At above 30 GPa, the degree of structural order increases and the
intermediate-range order structure depends strongly on pressure. Correlation between the peaks in
the plot of structure factor and the topology of basic structural units GeOn
(n = 4-6) is also discussed in...
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- Journal Article
Authors: Bui, Thi Hoa; Nguyen, The Nghia; Vi, Ho Phong; Tran, The Anh (2021) - This paper presents the evaluation of the Thick Target Particle Induced X-rays Emission
(TTPIXE) technique using standard samples. The element-dependent standardization factor, H, as a
function of X-ray energies is calibrated using standard sample NIST-611 and validated with two
standard samples: IAEA-Soil7 and NIES-Pepperbush. The obtained results are in good agreement
with the reference data
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- Journal Article
Authors: Nguyen, Van Toan; Pham, Van Nhat; Ta, Van Duong (2021) - Microsphere biolasers have attracted a great deal of interest due to their potential in
biosensing and cell-tracking. Various fabrication techniques have been explored for making
microsphere biolasers, such as freeze-drying in a vacuum, standard oil in water dispersion procedure
and protein dehydration in a solvent. The protein dehydration is highly interesting due to its
simplicity and fast processing time. In this work, we demonstrate the fabrication of microsphere
biolasers using protein dehydration in decanol and demonstrate that the fabrication process can
speed up if the solvent is heated. When the solvent is heated to 60 °C, the fabrication time is reduced
to half ...
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- Journal Article
Authors: Nguyen, Dinh Lam (2021) - Zinc oxide is known as an excellent material for biosensors, solar cells, semiconductors
and photocatalysts. In this work, n-ZnO nanorods/p-Si heterostructures were successfully fabricated
by a hydrothermal method at different baking temperatures. The n-ZnO nanorods/p-Si
heterostructures show good photocatalytic ability at high baking temperature. The concentration of
Rhodamine B can be decreased up to 97% after 150 min treated by the n-ZnO nanorods/p-Si
heterostructures grown at 80 oC. This result indicates that the n-ZnO nanorods/p-Si heterostructures are
capable of being used in the decomposition of organic compounds.
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- Journal Article
Authors: Tran, Tien Dung; Pham, The An1; Tran, Ba Duong; Nguyen, Khac Man; Nguyen, Thi Minh Hien; Tran, Hai Duc (2021) - This paper studies the effects of the sintering temperature on crystal structure, critical
temperature (Tc) and excess conductivity of Bi-Pb-Sr-Ca-Cu-O (BPSCCO) system. Bulk BPSCCO
samples were fabricated by the solid-state reaction method. Four different temperatures of 835 °C,
840 °C, 845 °C, and 850 °C were applied to sinter four different samples. The crystal structure of
the samples was investigated through X-ray diffraction measurements (XRD) and scanning electron
microscopy (SEM). Superconductivity of the samples was analyzed by the temperature-dependent
resistivity measurement. The experimental results showed the existence of both Bi-2223 and Bi 2212 phases in all ...
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- Journal Article
Authors: Nguyen, Hoang Nam; Nguyen, Thi Bich Ngoc; Truong, Thanh Trung; Tran, Thi Hong; Phi, Thi Huong; Nguyen, Hoang Luong (2021) - In this study, Fe50Pd50 nanoparticles with small size of around 5-9 nm were prepared by
sonoelectrodeposition in the presence of cetyltrimethylammonium bromide (CTAB) surfactant. The
as-prepared nanoparticles were annealed at 550oC for a series of times from 1 h to 6 h. After
annealing, a transformation from a disordered face-centered-cubic structure to the ordered L10
structure occurred. It was revealed that the coercivity of the nanoparticles was larger compared to
that of the samples prepared by the same method in the absence of CTAB. The structural and
magnetic properties of the samples were studied in dependence of annealing time. The results
indicate a similar behav...
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- Journal Article
Authors: Vu, Dinh Quang (2021) - This study analyses eccentrically stiffened sandwich thick plates with the core layer made
of negative poisson material. The analytical method based on the first order shear deformation theory
(FSDT) is applied to analyse dynamic response and vibration of the plates. The numerical results of
the study have been compared with other studies to evaluate the reliability of the calculation. The
analysis results of the nonlinear dynamic response and the vibration show that the elastic foundation
and the graphene volume ratio positively impact the behavior of the plates. On the other hand,
imperfection and thermal environment have a negative effect on the behavior of sandwich pla...
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- Journal Article
Authors: Nguyen, Van Dung; Le, Vinh Truong (2021) - Polypropylene laminated paper (PPLP) and Kraft paper have been studied as multi-layer
insulation for high temperature superconducting cable. The experiment was conducted with AC and
impulse voltages. Short-term and long-term breakdown of insulation samples were investigated. The
experimental results show that the breakdown voltage becomes smaller in the order of PPLP,
PPLP/Kraft and Kraft, but the lifetime index increases with the presence of Kraft layer in the multi layer insulation. In addition, the position of PPLP layers has a significant effect on the breakdown
voltage of PPLP/Kraft samples under positive impulse voltage. Finally, breakdown mechanism of
PPLP/Kraft com...
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- Journal Article
Authors: Nguyen, Thi Dung; Tran, Viet Phu; Donny, Hartanto; Luu, Thi Lan; Mai, Huu Thuan; Pham, Nhu Viet Ha (2021) - This paper presents the steady-state analysis results of the OECD/NEA and U.S. NRC
PWR MOX/UO2 (MOX: Mixed Oxide) Core Transient Benchmark with the modern MCNP6 Monte
Carlo code based on the ENDF/B-VII.1 evaluated nuclear data library. The purpose of the paper was
to verify an MCNP6 model proposed for calculations of a heterogeneous MOX/UO2 fuelled PWR
core, which has different neutronic characteristics from the popular homogeneous ones loaded with
the UO2 fuel due to its partial loading of the MOX fuel. The effective neutron multiplication factors,
assembly power distributions, and control rod worths calculated using MCNP6 showed a reasonable
agreement within 390 pcm, 6...
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- Journal Article
Authors: Pham, Van Tuan; Le, Trung Hieu; Vu, Thi Tan; Hoang, Ba Tuong; Tran, Thi Quynh Hoa; Nguyen, Xuan Sang; Tran, Ngoc Khiem (2021) - In this work, SnO2 nanoparticles were prepared by hydrothermal method using
SnCl4.5H2O and NaOH at 180 °C for different hydrothermal times. The effect of hydrothermal time
on the crystal structure, morphology, chemical bonding, and photocatalytic properties of SnO2
nanoparticles was studied. Structural and morphological characteristics of SnO2 nanoparticles were
investigated by X-ray diffraction and electron scanning microscopy analyses. Chemical bonding and
absorption properties of the prepared materials were analyzed by Fourier transform infrared
spectroscopy and UV-Vis absorption spectroscopy. Photocatalytic properties of SnO2 nanoparticles
were evaluated by the degrad...
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- Journal Article
Authors: Nguyen, Xuan Sang; Nguyen, Hoang Mai; Pham, Thi Thuy; Nguyen, Tri Tuan; Pham, Van Tuan; Hoang, Ba Cuong (2021) - Herein we report on a simple method to grow ZnO nanorod/Graphene oxide (GO) array
without the initial seed layer on a printed circuit board (PCB) as the substrate based on Galvanic
effect. The hydrothermal growing conditions such as temperature and time were investigated by X ray diffractometry (XRD), Raman scattering, as well as Scanning Electron Microscopy (SEM). It is
shown that the as-prepared ZnO nanorod was grown well-vertically on the substrate. Furthermore,
we investigated the photocatalytic activity of synthesized samples, which showed the enhanced
photodegradation ability in the composite sample
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- Journal Article
Authors: Tran, Manh Trung; Nguyen, Tu; Nguyen, Van Quang; Do, Quang Trung; Pham, Thanh Huy (2021) - In this study, red-emitting AlPO4:Cr3+ phosphors have been successfully synthesized by
a facile sol-gel method. The Tanabe–Sugano diagram demonstrates that the surrounding sites of
Cr3+ ions have a high crystal field with Dq/B=2.47. The sharp 694-nm peak on the PL of AlPO4:Cr3+
phosphor could be attributed to the 2E→4A2 electron transition of Cr3+ ions. The AlPO4:0.3%Cr3+
phosphor presents the highest PL intensity, then a purple LED prototype is obtained by coating the
optimum powder on a UV LED chip. The color coordinates (0.2412, 0.1330) of the purple LED
prototype imply that AlPO4:Cr3+ phosphors are promosing to be used as deep red phosphor powder
for horticulture LED l...
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- Journal Article
Authors: Le, Quoc Dat; Duong, Thanh Tung; Nguyen, Duy Hung (2021) - In this study, we synthesized K3AlF6:Mn4+ phosphor by co-precipitation method and
investigated its crystal structure and photoluminescence properties . By surface modification of
K3AlF6:Mn4+ using K3AlF6, the moisture resistance performance of the phosphor can be
significantly improved. It was found that the luminescence performance of K3AlF6:Mn4+@K3AlF6,
which was dispersed in water for 2 h, was unchanged but the uncoated sample reduced dramatically.
White light emitting diodes (WLEDs) based on the phosphor combined with commercial YAG:Ce3+
coated on a blue LED showed significant improvement of performance with color correlated
temperature (CCT) from 5307 K down to 3528 K...
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- Journal Article
Authors: Do, Ngoc Son; Nguyen, Thi Xuan Huynh; Nam, Thoai; Pham, Trung Kien (2021) - CO2 capture is indispensable for a cleaner environment and mitigation of global warming.
The pre-combustion CO2 capture relates to the separation of CO2 from H2 in the syngas mixture.
Recently, metal-organic frameworks have proven to be excellent candidates for this purpose. In the
current work, MIL-88A (Fe, V, Ti, Sc) were studied for the first time by using the grand canonical
Monte Carlo simulations for the CO2/H2 mixture. The adsorption capacity of CO2 and H2 in the
absence and presence of water medium in MIL-88A was analyzed. We found that the magnitude of
the CO2 capacity was many times higher than that of the H2 capacity, which led to rather high
CO2/H2 selectivit...
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- Journal Article
Authors: Doan, Thi Tu Uyen; Pham, Quynh Nhu Phuong; Mai, Ngoc Xuan Dat; Pham, Kim Ngoc (2021) - The resistive switching memory device based on nanocomposites has become a potential
candidate in the data storage field. Understanding resistive switching characteristics and electrical
conduction mechanisms may support the appropriate way to fabricate and control the operation of a
device. In this study, a capacitor-like structure using PVA-ZnO as an insulator layer was fabricated
by a solution method. The crystalline structure, morphology, and absorption spectrum of ZnO
nanoparticles were discussed respectively. The resistive switching effect was observed with the
ON/OFF ratio of 0.5102
, high endurance, excellent retention and the electrical transport
mechanisms we...
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- Journal Article
Authors: Nguyen, Thi Quynh Chi; Nguyen, Duc Minh; Vu, Ngoc Hung (2021) - The impact of the piezoelectric cantilever geometry and resonant mode on the quality
factor and mass-sensitivity was investigated. The piezoelectric cantilevers with Pb(Zr0.52Ti0.48)O3
(PZT) as an active layer were fabricated based on MEMS technology. The PZT thin films were
grown on the silicon-on-insulator substrates by pulsed laser deposition. It is shown that the resonant
frequency of a defined vibration mode is inversely proportional to the length squared of the
piezoelectric cantilever. The experimental results indicate that a shorter cantilever length contributes
to a larger quality factor. The cantilever quality factor has values in the range of 190 to 505,
dependi...
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- Journal Article
Authors: Dang, Trung Si; Nguyen, Thanh Phong; Nguyen, Hua Thanh Nha (2021) - In this paper, a new version of 3-3-1-1 model was proposed to solve the Landau pole
problem of the previous versions. The masses of fermions where the masses of active neutrinos are
generated through the seesaw mechanism, are calculated in detail. All the Higgs bosons and gauge
bosons as well as their masses are identified and calculated
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Collection's Items (Sorted by Submit Date in Descending order): 1 to 20 of 621
