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Structural and luminescent properties of (Eu,Tb) PO_4·H_2O nanorods/nanowires prepared by microwave technique

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Journal of Rare Earths 2011年第12期29卷 1170-1173页

作者： nguyen Thanh Huong nguyen Duc van Dinh Manh Tien Do Khanh Tung nguyen Thanh Binh Tran Kim anh Le Quoc Minh Institute of Materials Science Vietnam Academy of Science and Technology University of Engineering and Technology National University HanoiVietnam

Nanowires/nanorods of europium/terbium orthophosphate monohydrate with Eu^3＋ concentration of 6, 11, and 20 at.% were prepared by microwave synthesis method. The effects of Eu^3＋ doping concentration on structure, morphology and optical properties of nanomaterials were also investigated. The results showed that, for all studied Eu^3＋ doping concentrations, a single-crystalline phase of rhabdophane-type （Eu,Tb）PO4·H2O nanowires/nanorods was obtained by using microwave heating of an aqueous solution of terbium（Ⅲ） nitrate, europium（Ⅲ） nitrate and NH4H2PO4 with pH=2. The length and width of these nanowires/nanorods ranged from 150 to 300 nm and from 10 to 50 nm, respectively. The evidence of energy transfer from Tb^3＋ to Eu^3＋ due to the energy overlap between the donor Tb^3＋ and the acceptor Eu^3＋was observed obviously via a significant enhancement in the luminescent intensity of Eu^3＋. Keywords：

关键词： microwave technique nanowires/nanorods energy transfer fluorescence spectroscopy rare earths

Microwave absorption of magnesium/hydrogen-treated titanium dioxide nanoparticles

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Nano Materials Science 2019年第1期1卷 48-59页

作者： Michael Green anh thi van Tran Russell Smedley Adam Roach James Murowchick Xiaobo Chen Department of Chemistry University of Missouri-Kansas City Kansas City MO 64110 USA Department of Geosciences University of Missouri-Kansas City Kansas City MO 64110 USA

Interactions between materials and electromagnetic irradiations in the microwave frequency are critical for many civil and military applications, such as radar detection, communications, information processing and transport et al. Dipole rotations or magnetic domain resonance are the mainly traditional mechanisms for microwave absorption. The recent finding of the excellent microwave absorption from hydrogenated TiO2 nanoparticles provides us an alternative approach for achieving such absorption, by manipulating the structural defects inside nanoparticles through hydrogenation. In this study, we demonstrate that the microwave absorption can be not only achieved but fine-tuned with TiO2 nanoparticles thermally treated in a Mg/H2 environment. Their position and efficiency can be effectively controlled by the treating temperature. Specifically, the microwave absorption position shifts to the lower frequency region as the treating temperature increases, and there seems to exist an optimal treating temperature to obtain the maximum efficiency, as the absorbing efficiency first increases, and then decreases, with the increase in treatment temperature. Therefore, this study enriches our knowledge and understanding microwave absorption from TiO2-based nanomaterials which may inspire new ideas on other systems to enhance their performance as well.

关键词： Hydrogenation Reflection loss Permittivity Permeability Microwave absorption

How to Motivate Students to Learn Listening Effectively？

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Sino-US English Teaching 2014年第2期11卷 101-110页

作者： Huong Hoa Le van anh nguyen thi Vietnam National University Hanoi Capital Vietnam Police University Ho Chi Minh City Vietnam

this paper reports a study that used a matched-pair pre-test, post-test control group design to compare the impacts of IL （intensive listening） program and EL （extensive listening） program on the learners＇ listening proficiency based on the 30-day experiment. It is hoped that the study can help Vietnamese learners who study EFL （English as a foreign language） develop a positive attitude towards EL on one hand, and may motivate them to listen for pleasure on the other hand. this study may shed light on how to introduce EL into English foreign language classroom practice and how to maximize the students＇ exposure to suitable listening materials, which has been effectively adapted and reproduced, for the real classroom practice

关键词： motivate IL (intensive listening) EL (extensive listening)

STRONG CONVERGENCE OF AN INERTIAL EXTRAGRADIENT METHOD WITH AN ADAPTIVE NONDECREASING STEP SIZE FOR SOLVING VARIATIONAL INEQUALITIES

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Acta Mathematica Scientia 2022年第2期42卷 795-812页

作者： nguyen Xuan LINH Duong Viet THONG Prasit CHOLAMJIAK Pham anh TUAN Luong van LONG Department of Mathematics Mathematics Falcuty of Information TechnologyNational University of Civil Engineering Division of Applied Mathematics Thu Dau Mot UniversityBinh Duong ProvinceVietnam School of Science University of PhayaoPhayao 56000Thailand Paculty of Mathematical Economics National Economics UniversityHanoi CityVietnam

In this work,we investigate a classical pseudomonotone and Lipschitz continuous variational inequality in the setting of Hilbert space,and present a projection-type approximation method for solving this *** method requires only to compute one projection onto the feasible set per iteration and without any linesearch procedure or additional projections as well as does not need to the prior knowledge of the Lipschitz constant and the sequentially weakly continuity of the variational inequality mapping.A strong convergence is established for the proposed method to a solution of a variational inequality problem under certain mild ***,we give some numerical experiments illustrating the performance of the proposed method for variational inequality problems.

关键词： Inertial method Tseng’s extragradient viscosity method variational inequality problem pseudomonotone mapping strong convergence

Study of vertically ascending flight of a hawkmoth model

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Acta Mechanica Sinica 2020年第5期36卷 1031-1045,I0002页

作者： anh Tuan nguyen Vu Dan Thanh Le The Hung Tran V.N.Due van Binh Phung Faculty of Aerospace Engineering Le Quy Don Technical UniversityHanoiVietnam Institute of Theoretical and Applied Research.Duy Tan University HanoiVietnam Division of Construction Computation Institute for Computational ScienceTon Due Thang UniversityHo Chi Minh CityVietnam Faculty of Civil Engineering Ton Due Thang UniversityHo Chi Minh CityVietnam

this paper provides insight into the wing kinematics,the power requirement and the dynamic stability characteristics of a hawkmoth model in vertically ascending *** wing kinematics of the hawkmoth model is obtained based on the minimum required power *** optimization process is conducted using genetic and simplex algorithms that are coupled with an artificial neural network to rapidly predict the aerodynamic force and required *** training data for the neural network are generated from an unsteady vortex-lattice *** to hover,the results in this study show the larger flapping frequency and the smaller rotation amplitude of the hawkmoth wing kinematics in ascending ***,more power is required when the ascending speed *** conducting a dynamic modal analysis based on a cycle-average approach,the certain effect of the ascending speed on the modal structures of the hawkmoth model was observed.

关键词： Hawkmoth Ascending flapping flight-Genetic algorithm Artificial neural network Flight dynamic stability

The impact of plasmonic Ag−Au bimetallic nanoparticles on photocurrent enhancement in GaN-based photodetectors

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Journal of Semiconductors 2024年第12期45卷 72-78页

作者： thi Kim Oanh Vu thi Thu Phuong Bui Ngoc anh nguyen thi Thanh Bao nguyen thi Minh Hien nguyen Eun Kyu Kim No.10 Dao Tan Institute of PhysicsVietnam Academy of Science and TechnologyNo.10 Dao TanHanoi 118000Vietnam Graduate University of Science and Technology Vietnam Academy of Science and Technology18 Hoang Quoc VietHanoi 122300Vietnam Department of Physics and Research Institute for Natural Sciences Hanyang UniversitySeoul 04763Republic of Korea

Recently,there has been considerable interest in high-efficiency ultraviolet(UV)photodetectors for their potential practical *** this study,a high-quality UV photodetector was fabricated using a combination of Ag and Au NPs with GaN *** GaN film was deposited using sputtering technique,whereas Ag and Au films were grown using thermal evaporation ***-Au bimetallic nanoparticles were formed by treating them at the various annealing temperature to improve the interaction between light and the photoactive layers of the *** optimal annealing temperature to achieve the best performance of a photodetector is 650℃.this led to a photoresponsivity of 98.5 A/W and the ON/OFF ratio of 705 at low bias voltage of 1 *** work establishes the foundation for the advancement of high-performance UV photodetectors.

关键词： UV photodetectors GaN Ag-Au bimetallic nanoparticles plasmonic effect

Effects of Processing Parameters on Mechanical Properties and Structure of Banana Fiber-Reinforced Composites

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Journal of Renewable Materials 2018年第6期6卷 662-670页

作者： Dan-Thuy van-Pham Minh Tri nguyen Chanh-Nghiem nguyen thi Truc Duyen Le thi Yen Nhu Pham Khai thinh nguyen Yukihiro Nishikawa Qui Tran-Cong-Miyata Department of Chemical Engineering Can Tho UniversityCan Tho CityViet Nam Department of Automation Technology Can Tho UniversityCan Tho CityViet Nam Department of Macromolecular Science and Engineering Graduate School of Science and TechnologyKyoto Institute of TechnologyMatsugasakiSakyo-kuKyoto 606-8585Japan

The mechanical properties of unidirectional natural fiber-reinforced composites are generally affected by several processing parameters during compression *** study investigates the effects of processing temperature,time,and pressure on the tensile and flexural properties of acrylonitrile butadiene styrene reinforced by banana fibers.X-ray CT imaging was employed to find the relationship between the mechanical properties and structure of the processed ***,the water absorption of composites was observed and the way in which the mechanical properties evolved after water absorption was *** tensile and flexural properties of the unidirectional banana fiber-reinforced composite were found to be inversely proportional to the *** addition,high-pressure compression molding might result in cracks and floating fibers that would significantly reduce its mechanical *** composite with the highest strength,smallest porosity and lowest water absorption was optimally prepared at T=170℃,t=20 min,and P=100 kg cm^-2.

关键词： Banana fiber composite compression molding porosity X-ray CT

Generating highly active oxide-phosphide heterostructure through interfacial engineering to break the energy scaling relation toward urea-assisted natural seawater electrolysis

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Journal of Energy Chemistry 2024年第10期97卷 687-699,I0014页

作者： Ngoc Quang Tran Nam Hoang Vu Jianmin Yu Khanh Vy Pham nguyen Thuy Tien nguyen Tran Thuy-Kieu Truong Lishan Peng thi anh Le Yoshiyuki Kawazoe Center for Innovative Materials and Architectures Ho Chi Minh City 700000Vietnam Vietnam National University Ho Chi Minh City 700000Vietnam Faculty of Materials Science and Technology University of ScienceHo Chi Minh City 700000Vietnam Department of Mechanical Engineering Hanbat National University(HBNU)Daejeon 34158Republic of Korea Key Laboratory of Rare Earths Ganjiang Innovation AcademyChinese Academy of SciencesGanzhou 341119JiangxiChina School of Chemical Engineering-Hanoi University of Science and Technology Hanoi 10000Vietnam New Industry Creation Hatchery Center Tohoku UniversitySendai 980-8579Japan

Urea-assisted natural seawater electrolysis is an emerging technology that is effective for grid-scale carbon-neutral hydrogen mass production yet *** scaling relations is an effective strategy to break through the bottleneck of natural seawater ***,by DFT calculation,we demonstrated that the interface boundaries between Ni_(2)P and MoO_(2) play an essential role in the selfrelaxation of the Ni-O interfacial bond,effectively modulating a coordination number of intermediates to control independently their adsorption-free energy,thus circumventing the adsorption-energy scaling *** this conceptual model,a well-defined 3D F-doped Ni_(2)P-MoO_(2) heterostructure microrod array was rationally designed via an interfacial engineering strategy toward urea-assisted natural seawater *** a result,the F-Ni_(2)P-MoO_(2) exhibits eminently active and durable bifunctional catalysts for both HER and OER in acid,alkaline,and alkaline sea water-based *** in-situ analysis,we found that a thin amorphous layer of NiOOH,which is evolved from the Ni_(2)P during anodic reaction,is real catalytic active sites for the OER and UOR ***,such electrode-assembled urea-assisted natural seawater electrolyzer requires low voltages of 1.29 and 1.75 V to drive 10 and600 mA cm^(-2)and demonstrates superior durability by operating continuously for 100 h at 100 mA cm^(-2),beyond commercial Pt/C||RuO_(2) and most previous reports.

关键词： Interfacial engineering Break scaling relationships Doping Natural seawater splitting Urea electrolysis

Performance Comparison of Chemically Modified Sugarcane Bagasse for Removing Cd(II) in Water Environment

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Journal of Renewable Materials 2019年第5期7卷 415-428页

作者： Manh Khai nguyen Minh Trang Hoang thi Thuy Pham Bart van der Bruggen Falculty of Environmental Science VNU University of Science334 Nguyen TraiHanoiVietnam Laboratory for Process Engineering for Sustainable Systems Department of Chemical EngineeringKU LeuvenBelgiumCelestijnenlaan 200F3001 LeuvenBelgium

this paper evaluates the adsorption capacity of chemically sugarcane bagasses with sodium hydroxide(SHS),citric acid(CAS),tartaric acid(TAS)and unmodified sugarcane bagasse(SB)for cadmium adsorption in water *** results prove adsorption capacity for Cd(II)increases after chemical modification and the adsorption fits perfectly with the Langmuir *** had the highest maximum adsorption capacity of 45.45 mg/g followed by TAS with 38.46 mg/g and SHS with 29.41 at optimum pH 5.0 and 120 minutes equilibrium time while 1 g SB removed 18.8 mg Cd(II)in the same *** kinetics study of the process followed a pseudo-secondorder rate expression,that indicated a strong interaction between the biosorbents and *** sugarcane bagasse and modified sugarcane bagasse were characterized by scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FTIR)*** chemical modification was confirmed by the presence of carboxyl and esters groups created at 1,738 *** estimation of acid groups in modified materials shows the enhancement of this group after *** the other hand,desorption studies showed the high leaching of cadmium ion from the biosorbent leading to the efficient reutilization of materials.

关键词： Cadmium chemical modification citric acid sugarcane bagasse