Adaptive Perturbation-Aided Opportunistic Beamforming

Le, Thuan Van,Lee, Kyungchun IEEE 2018 IEEE communications letters Vol.22 No.8

<P>This letter proposes a novel opportunistic beamforming algorithm, called adaptive perturbation-aided opportunistic beamforming. In each time slot, the proposed algorithm makes a random adjustment to the beamforming vector. Then, for data transmission, it adopts the successful perturbation, which yields performance improvements. By contrast, the failed perturbation is discarded. In addition to random perturbation, an adaptive component, which depends on the feedback information, is added to generate the next beamforming vector. Simulation results show that the proposed scheme provides significant improvement in terms of system throughput, especially, when there is a small number of mobile stations.</P>

Enhanced photocatalytic degradation of reactive blue 19 using zeolitic imidazolate framework-8 composited with Fe3O4/MnO2 heterojunction

Van Thuan Le,Hoang Sinh Le,Vy Anh Tran,이상화,Van-Dat Doan,주상우,Yasser Vasseghian 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-

The present study offers a novel recyclable Fe3O4/MnO2/ZIF-8 heterojunction photocatalyst for the degradationof reactive blue 19 (RB19) under visible light irradiation. The catalyst was facilely synthesized bydepositing Fe3O4/MnO2 nanocomposite onto the surface of ZIF-8 and characterized by field-emissionscanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy,X-ray diffraction, nitrogen adsorption–desorption isotherms and UV–vis spectroscopy. Morphology and structure characterization of the prepared photocatalyst indicated that polyhedralZIF-8 (ca. 500 nm) was coated by MnO2/Fe3O4 nanorods. The synergy effect of Fe3O4/MnO2/ZIF-8 compositeexhibited an excellent photocatalytic activity toward RB19 degradation of 99.5 % after 60 min of irradiationdue to high surface area and heterojunction formation. According to scavenger tests, thephotodegradation of RB19 dye over Fe3O4/MnO2/ZIF-8 was mainly contributed by OH and O2reactiveradicals. The kinetic study showed that the catalytic degradation of RB19 on Fe3O4/MnO2/ZIF-8 was betterdescribed by the first-order kinetic model. The new catalyst was easily recovered using an external magneticfield because of its magnetic properties. Besides, Fe3O4/MnO2/ZIF-8 showed high recyclability andstability, maintaining a high removal efficiency of 91.3 % even after ten repeated cycles. The overallresults indicated that the fabricated composite can be used as an efficient photocatalyst for treatingorganic dyes in wastewater.

Application of Cost-Volume-Profit Analysis in Decision-Making by Public Universities in Vietnam

LE, Oanh Thi Tu,TRAN, Phong Thi Thu,TRAN, Thuan Van,NGUYEN, Cong Van Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.6

This paper aims to examine the application of cost-volume-profit (CVP) analysis by public universities in Vietnam. In the context where Vietnam is gradually transferring financial autonomy to public universities, the conduct of a CVP analysis in relation to these public universities is particularly urgent. Research samples were collected in 2018 and 2019 by surveying Vietnamese public universities. After collection, the data is synthesized by excel file, conformity check, data cleansing and data analysis on SPSS software by tools such as Frequency statistics, price statistics, and means. The results show that: (1) universities used the CVP analysis in decision-making, (2) information related to the CVP analysis used for decision-making by administrators remained simplistic and lacked cost-control details, and (3) the application of the CVP analysis by university administrators for decision-making was neither comprehensive nor coordinated. The findings also show that, given the current conditions in Vietnam, increasing the governance in public universities is essential, as is contributing to reducing costs, increasing universities'income, providing the best service to students, and improving the quality of training. The study calls for the flexible application of the CVP analysis, which will provide information to help managers at Vietnamese public universities make the best decisions.

Effect of thermolysis condition on characteristics and nonsteroidal anti-inflammatory drugs (NSAIDs) absorbability of Fe-MIL-88B-derived mesoporous carbons

Van Tran, Thuan,Nguyen, Duyen Thi Cam,Le, Hanh T.N.,Bach, Long Giang,Vo, Dai-Viet N.,Dao, To-Uyen T.,Lim, Kwon Taek,Nguyen, Trinh Duy Elsevier 2019 Journal of environmental chemical engineering Vol.7 No.5

<P><B>Abstract</B></P> <P>Discharge of nonsteroidal anti-inflammatory drugs (NSAIDs) from wastewater has been increasingly alarmed, led to the advent of the treatment techniques. Among these methods, adsorption is regarded as a tunable and green approach with the utilization of mesoporous carbon (MC) as an efficient and recyclable adsorbent. Herein, we described the strategy for the synthesis of novel MC from Fe-MIL-88B as a self-sacrificial template. Three thermolysis temperatures (550, 750, and 950 °C) were investigated to compare the structural characteristics and absorbability towards selected NSAIDs compounds including diclofenac sodium (DCF), aspirin (APR), and ibuprofen (IBU). Effect of contact time (0–480 min), concentration (10–40 mg/L), pH (2–10), and MC dosage (0.1–0.5 g/L) was systematically studied. Kinetic and isotherm models were also used to find out the adsorption mechanism and behavior of NSAIDs pharmaceutical over MC materials. Proposed mechanism and recyclability test were rigorously studied to gain more insight into how the NSAIDs molecules adsorb on the MC materials and their potential towards drug treatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effect of thermolysis temperature on characteristics and absorbability towards anti-inflammatory drugs was conducted. </LI> <LI> Kinetic, isotherm, and recyclability experiments were systematically studied. </LI> <LI> Adsorption mechanisms including H-bond, π–π interaction, metal–oxygen bridging, and electrostatic attraction were rigorously proposed. </LI> <LI> Outstanding adsorption capacity (∼144 mg/g), and excellent reusability were monitored with Fe-MIL-88B-derived mesoporous carbon. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Magnetoresistance Effect in La0.7Sr0.3MnO3 Thin Films Fabricated by Using Pulsed Laser Deposition

Nguyen Van Dai,Nguyen Chi Thuan,Le Van Hong,Nguyen Xuan Phuc 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

La0:7Sr0.₃MnO₃ thin films were fabricated onto (100) n-Si substrates by using pulsed laser deposition (PLD). The thickness of the lms was controlled from 30 nm to 100 nm by varying deposition time. The deposited lms were then annealed at 600℃ for 5 h. Room-temperature X-ray patterns verifed that the lms had a La0:7Sr0:3MnO3 single phase as did the target. The crystalline orientation of the lms was in uenced by the lms thickness. Thinner lms were more oriented in the (104) direction. The Magnetoresistance (MR) measured at 300 K for all the lms exhibited a pure DE behavior that depended on the films thickness. A nonlinear eld dependence of the magnetoresistance was observed in the temperature region far below TC. This obtained result could not be explained by the DE mechanism. Fitting experimental data to the spin polarized tunneling model, we attributed the dominated low-field MR below TC to spin polarized tunneling between grain boundaries. La0:7Sr0.₃MnO₃ thin films were fabricated onto (100) n-Si substrates by using pulsed laser deposition (PLD). The thickness of the lms was controlled from 30 nm to 100 nm by varying deposition time. The deposited lms were then annealed at 600℃ for 5 h. Room-temperature X-ray patterns verifed that the lms had a La0:7Sr0:3MnO3 single phase as did the target. The crystalline orientation of the lms was in uenced by the lms thickness. Thinner lms were more oriented in the (104) direction. The Magnetoresistance (MR) measured at 300 K for all the lms exhibited a pure DE behavior that depended on the films thickness. A nonlinear eld dependence of the magnetoresistance was observed in the temperature region far below TC. This obtained result could not be explained by the DE mechanism. Fitting experimental data to the spin polarized tunneling model, we attributed the dominated low-field MR below TC to spin polarized tunneling between grain boundaries.

Constituents from the Stem Barks of Canarium bengalense with Cytoprotective Activity against Hydrogen Peroxide-induced Hepatotoxicity

Hoang Thi Le,나민균,Do Thi Ha,Chau Thi Anh Minh,Tae Hoon Kim,Phan Van Kiem,Nguyen Duy Thuan 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.1

Phytochemical investigation of the stem barks of Canarium bengalense (Burseraceace) resulted in the isolation of a new flavone glycoside (5) together with six known compounds (1-4, 6, and 7). The chemical structure of the new compound was elucidated as 3'-hydroxy-7,4'-dimethoxyflavone-5-O-α-L-arabinofuranosyl-(1→6)-β-D-glucopyranoside by means of 1D and 2D NMR (1H-1H COSY, HMQC, and HMBC) and MS analyses. To evaluate the in vitro cytoprotective effect, the isolates (1-7) were tested against hydrogen peroxide (H2O2)-induced damage in primary cultured hepatocytes. The viability of hepatocytes was increased by treatment with each compound, except compound 1. Compounds 3, 4, and 7 exerted cytoprotective effects comparable to curcumin, the positive control. Our results suggest that the cytoprotective constituents of C. bengalense may contribute to its traditional use in the treatment of tumor and liver damage.

Physiological intracytoplasmic sperm injection does not improve the quality of embryos: A cross-sectional investigation on sibling oocytes

Minh Tam Le,Hiep Tuyet Thi Nguyen,Trung Van Nguyen,Thai Thanh Thi Nguyen,Hong Nhan Thi Dang,Thuan Cong Dang,Quoc Huy Vu Nguyen The Korean Society for Reproductive Medicine 2023 Clinical and Experimental Reproductive Medicine Vol.50 No.2

Objective: This study aimed to compare the efficacy of physiological intracytoplasmic sperm injection (PICSI) and intracytoplasmic sperm injection (ICSI) in terms of the fertilization rate and embryo quality using sibling oocyte cycles. Methods: This prospective, cross-sectional study collected data from 76 couples who underwent their first cycle at the Hue Center for Reproductive Endocrinology and Infertility, Vietnam, between May 2019 and November 2021. The inclusion criteria were cycles with at least eight oocytes and a sperm concentration of 5×10⁶/mL. Sperm parameters, sperm DNA fragmentation (SDF), fertilization, and the quality of cleavage-stage embryos on day 2 and blastocysts on day 5 were examined. Results: From 76 ICSI cycles, 1,196 metaphase II (MII) oocytes were retrieved, half of which were randomly allocated to either the PICSI (n=592) or ICSI (n=604) treatment group. The results showed no significant difference between the two groups in terms of fertilization (72.80% vs. 75.33%, p=0.32), day 2 cleavage rate (95.13% vs. 96.04%, p=0.51), blastulation rate (52.68% vs. 57.89%), and high-quality blastocyst rate (26.10% vs. 31.13%, p=0.13). However, in cases where SDF was low, 59 cycles consisting of 913 MII oocytes produced a considerably higher blastulation rate with PICSI than with ICSI (50.49% vs. 35.65%, p=0.00). There were no significant differences between the pregnancy outcomes of the PICSI and ICSI embryo groups following embryo transfer. Conclusion: Using variable sperm quality provided no benefit for PICSI versus ICSI in terms of embryo outcomes. When SDF is low, PICSI appears to be able to produce more blastocysts.

The UO₂ ex-ADU powder preparation and pellet sintering for optimum efficiency: experimental and modeling studies

Hung, Nguyen Trong,Thuan, Le Ba,Van Tung, Nguyen,Thuy, Nguyen Thanh,Lee, Jin-Young,Jyothi, Rajesh Kumar ELSEVIER 2017 JOURNAL OF NUCLEAR MATERIALS Vol.496 No.-

<P><B>Abstract</B></P> <P>The UO<SUB>2</SUB> nuclear fuel pellet process for light water reactors (LWR) includes the conversion of uranium hexafluoride (UF<SUB>6</SUB>) into UO<SUB>2</SUB> powder and the fabrication of UO<SUB>2</SUB> pellets from such UO<SUB>2</SUB> powder. In the paper, studies on UO<SUB>2</SUB> pellet process from ammonium diuranate-derived uranium dioxide powder (UO<SUB>2</SUB> ex-ADU powder) were reported. The UO<SUB>2</SUB> ex-ADU powders were converted from ADU at various temperatures of 973 K, 1023 K and 1073 K and then UO<SUB>2</SUB> pellets prepared from the powders were sintered at temperatures of 1923 K, 1973 K and 2023 K for times of 4 h, 6 h and 8 h. Response surface methodology (RSM) based on quadratic central composite design (CCD) type of face centered (CCF) improved by Box and Hunter was used to model the UO<SUB>2</SUB> pellet process, using MODDE 5.0 software as an assessing tool. On the base of the proposed model, the relationship between the technological parameters and density of the UO<SUB>2</SUB> pellet product was suggested to control the UO<SUB>2</SUB> ex-ADU pellet process as desired levels.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Modeling and experimental studies were made on UO<SUB>2</SUB> ex-ADU powder preparation. </LI> <LI> Time, temperature studies made on UO<SUB>2</SUB> ex-ADU powder. </LI> <LI> Parameters were optimized through modeling the UO<SUB>2</SUB> pellet processes using RSM based CCD. </LI> <LI> The quadratic mathematical model for the pellet density was determined. </LI> <LI> The proposed model was shown a good agreement with the experimental data. </LI> </UL> </P>

Enhanced adsorption of cationic and anionic dyes using cigarette butt-based adsorbents: Insights into mechanism, kinetics, isotherms, and thermodynamics

Tran Thi Kieu Ngan,Le Van Thuan,Nguyen Tien Hoang,Doan Van Dat,Vasseghian Yasser,Le Hoang Sinh 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7

The present study provides an eco-friendly and economical way to recycle discarded cigarette butts (CBs). The raw CBs were treated with NaOH (CB-B) and integrated with chitosan (Cs), and further applied as an adsorbent for the removal of synthetic dyes. Two common cationic dyes of methylene blue (MB) and crystal violet (CV) and one anionic dye of reactive blue 19 (RB 19) were selected as model adsorbates. The study results revealed that CB-B showed a high adsorption ability toward cationic dyes, while the CB-B/Cs composite exhibited a stronger affinity for the anionic RB 19. The adsorption of all selected dyes onto CB-B and CB-B/Cs was a spontaneous exothermic process, conforming to the pseudo-first-order kinetic and Langmuir isotherm models. The maximum adsorption capacities for MB, CV and RB 19 at pH of 7, an adsorbent dosage of 4, and a temperature of 25 °C were 89.85, 82.41, and 304.49 mg/g, respectively. The primary adsorption mechanism was physical adsorption with the participation of electrostatic attraction. The CB-based adsorbents displayed high reusability, maintaining more than 75% after four consecutive cycles of reuse. This study demonstrates the promising application potential of CB-based adsorbents for treating synthetic dyes in wastewater. The conversion of CBs into a useful high-value material has special significance for environmental engineering.

La<SUB>0.7</SUB>Ca<SUB>0.3</SUB>MnO₃ Nanoparticles Synthesized by Reactive Milling: Influence of Milling Time on Grain Morphology and Magnetic Properties

Do Hung Manh,Nguyen Chi Thuan,Pham Thanh Phong,Le Van Hong,Nguyen Xuan Phuc 한국자기학회 2008 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-