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Upconversion luminescence of Gd2O3:Er3+and Gd2O3:Er3+/silica nanophosphors fabricated by EDTA combustion method

Journal of Rare Earths 2019年第11期37卷 1126-1131页

作者： Le Quoc Minh Tran Kim Anh nguyen Duy Hung Pham thi Minh Chau nguyen thi Quy Hai Ho Van Tuyen Vu thi Thai Ha Vu Duc Tu Wieslaw Strek Institute of Theoretical and Applied Research Duy Tan UniversityDa Nang 55000Viet Nam Advanced Institute for Science and Technology Hanoi University of Science and Technology1 Dai Co VietHai Ba TrungHanoiViet Nam Institute of Materials Science Vietnam Academy of Science and Technology18 Hoang Quoc Viet RoadCau Giay DistrictHanoiViet Nam Institute of Low Temperature and Structure Research Polish Academy of Science 2 OkolnaWroclawPoland

Gd2O3:Er^3+nanophosphors were fabricated by the combustion method in presence of Na2 ethylene diamine tetra acetic acid(EDTA-Na2)as fuel at not high temperature(≤350℃)within a very short time of 5 *** added concentration of Er^3+ions in Gd2O3 matrix was changed from 0.5 mol%to 5.0 mol%.The X-ray diffraction pattern of samples indicates the monoclinic structure of Gd2O3:Er^3+.The morphology and chemical composition analysis of the Gd2O3:Er^3+samples are characterized by a field emission scanning electron microscope(FESEM)and a Fourier-transform infrared spectrometer(FTIR).The photoluminescence(PL),photo luminescence excitation(PLE)and upconversion(UC)at room temperature of the prepared materials with different concentrations of Er^3+were *** PL of Gd2O3:Er^3+nanomaterials are shown in visible at 545,594,623,648,688 nm under excitation at 275 *** emission bands from transitions of Er^3+from 2P3/2 to 4F9/2 are observed,UC luminescent spectra of the Gd2O3:Er^3+/silica nanocomposites under 976 nm excitation show the bands at 548 and 670 *** influence of excitation power at 980 nm for transitions were measured and *** results indicate that the upconversion process of Gd2O3:Er^3+/silica is two photons absorption *** low temperature dependence of UC luminescent intensities of the main bands of Gd2O3:Er^3+was investigated towards development of a nanotemperature sensor in the range of 10-300 K.

关键词： Upconversion luminescence Gd2O3:Er3+ Gd2O3:Er3+/silica Nanophosphors EDTA combustion Rare earths

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Investigation of Polymorphisms in Coding Region of OsHKT1in Relation to Salinity in Rice

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Rice science 2016年第6期23卷 334-338页

作者： pham quynh-hoa tran xuan-an nguyen thi-nha-trang tran thi-thuy-anh hoang hai-yen nguyen thi-hong-van tang thi-hanh do thi-phuc Faculty of Biology VNU University of ScienceHanoi334 Nguyen TraiThanh XuanHanoiVietnam Faculty of Agronomy Vietnam National University of AgricultureNgo Xuan Quang StreetTrau QuyGia LamHanoiVietnam

Rice （Oryza sativa） is sensitive to salinity, but the salt tolerance level differs among cultivars,which might result from natural variations in the genes that are responsible for salt tolerance. High-affinitypotassium transporter （HKTs） has been proven to be involved in salt tolerance in plants. Therefore, wescreened for natural nucleotide polymorphism in the coding sequence of OsHKT1, which encodes the HKTprotein in eight Vietnamese rice cultivars differing in salt tolerance level. In total, seven nucleotidesubstitutions in coding sequence of OsHKT1 were found, including two non-synonymous and five synonymoussubstitutions. Further analysis revealed that these two non-synonymous nucleotide substitutions （G50Tand T1209A） caused changes in amino acids （Gly17Val and Asp403Glu） at signal peptide and the loop ofthe sixth transmembrane domain, respectively. To assess the potential effect of these substitutions on theprotein function, the 3D structure of HKT protein variants was modelled by using PHYRE2 webserver. Theresults showed that no difference was observed when compared those predicted 3D structure of HKTprotein variants with each other. In addition, the codon bias of synonymous substitutions cannot clearlyshow correlation with salt tolerance level. It might be interesting to further investigate the functional roles ofdetected non-synonymous substitutions as it might correlate to salt tolerance in rice.

关键词： polymorphism salt stress OsHKT1 gene rice

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An Ontology-Based Question Answering System for University Admissions Advising

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Intelligent Automation & Soft Computing 2023年第4期36卷 601-616页

作者： thi Thanh Sang nguyen Dang Huu Trong Ho Ngoc Tram Anh nguyen School of Computer Science and Engineering International UniversityVNU-HCMCVietnam National UniversityHo Chi Minh CityVietnam

Question-Answer systems are now very popular and crucial to support human in automatically responding frequent questions in manyﬁ***,these systems depend on learning methods and training ***,it is necessary to prepare such a good dataset,but it is not an easy *** ontol-ogy-based domain knowledge base is able to help to reason semantic information and make effective answers given user *** study proposes a novel chatbot model involving ontology to generate efﬁcient responses automatically.A case study of admissions advising at the International University–VNU HCMC is taken into account in the proposed chatbot.A domain ontology is designed and built based on the domain knowledge of university admissions using Protégé.The Web user interface of the proposed chatbot system is developed as a prototype using *** includes a search engine reasoning the ontology and generat-ing answers to users’*** experiments are carried out to test how the system reacts to different ***ﬁrst experiment examines questions made from some templates,and the second one examines normal questions taken from frequent *** results have shown that the ontology-based chatbot can release meaningful and long *** results are analysed to prove the proposed chatbot is usable and promising.

关键词： Ontology chatbots answer-question systems domain knowledge base admissions advising

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Gravity-Driven Instability in a Liquid Film Overlying an Inhomogeneous Porous Layer

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Chinese Physics Letters 2011年第2期28卷 144-147页

作者： ZHAO Si-Cheng LIU Qiu-Sheng nguyen-thi Henri BILLIA Bernard Key Laboratory of Microgravity Institute of MechanicsChinese Academy of SciencesBeijing 100190 IM2NP UMR CNRS 6137Universitéd’Aix-Marseille III13397 Marseille Cedex 20France

A new model consisting of a liquid film overlying a saturated and inhomogeneous porous layer is *** concentrate on effects of inhomogeneity on transition of instability *** of the averaged porosity and the gradient of porosity distribution on the instability behaviors of a liquid-porous layer system are *** average permeability of the porous layer is a key factor to determine the penetration of convection in the system.

关键词： porosity porous layer

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Optimization, equilibrium, adsorption behavior and role of surface functional groups on graphene oxide-based nanocomposite towards diclofenac drug

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Journal of Environmental Sciences 2020年第7期32卷 137-150页

作者： Thuan Van Tran Duyen thi Cam nguyen Hanh TNLe Dai-Viet NVo Sonil Nanda Trinh Duy nguyen nguyen Tat Thanh Hi-Tech Institute Nguyen Tat Thanh UniversityHo Chi Minh City 755414Viet Nam Center of Excellence for Green Energy and Environmental Nanomaterials(CE@GrEEN) Nguyen Tat Thanh UniversityHo Chi Minh City 755414Viet Nam Institute of Hygiene and Public Health Ho Chi Minh City 700000Viet Nam Department of Chemical and Biochemical Engineering University of Western OntarioLondonOntarioCanada

Aquatic contamination of diclofenac(DCF),an emergent non-steroidal anti-inflammatory drug(NSAIDs),can result in adverse effects to many ecosystems through ***,introducing effective remediation techniques to sequester the pharmaceutical wastes is highly fundamental to prevent their accumulation in the ***,adsorption has been presented as a green and efficient ***,we report the characterization and application of the novel magnetic nanocomposite(GO@CoFe2O4)derived from cobalt-based ferrite(CoFe2O4)and graphene oxide(GO)for DCF *** the optimization procedure,the response surface methodology(RSM)was adopted to investigate the impacts of DCF concentration(1.6-18.4 mg/L),DCF dosage(0.08-0.92 g/L),and solution pH(2.6-9.4)to find the optimum conditions for DCF removal,at 10.5 mg/L,0.74 g/L,and pH 4,*** the adsorption experiments,the kinetic,isotherm,thermodynamic,and intraparticle diffusion models were systematically ***,we have elucidated the role of functional groups on the surface of GO@CoFe2O4 in enhancing the adsorption of DCF *** good removal efficiency(up to 86.1%),high maximum adsorption capacity(32.4 mg/g),GO@CoFe2O4 can be a potential candidate to eliminate DCF drug from water.

关键词： Diclofenac sodium Graphene oxide Magnetic nanocomposite Response surface methodology Pharmaceuticals adsorption

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Object Detection in Remote Sensing Images Using Picture Fuzzy Clustering and MapReduce

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Computer Systems Science & Engineering 2022年第12期43卷 1241-1253页

作者： Tran Manh Tuan Tran thi Ngan nguyen Tu Trung Faculty of Computer Science and Engineering Thuyloi University175 Tay SonDong DaHanoi010000Vietnam

In image processing, one of the most important steps is image segmentation. The objects in remote sensing images often have to be detected in order toperform next steps in image processing. Remote sensing images usually havelarge size and various spatial resolutions. Thus, detecting objects in remote sensing images is very complicated. In this paper, we develop a model to detectobjects in remote sensing images based on the combination of picture fuzzy clustering and MapReduce method (denoted as MPFC). Firstly, picture fuzzy clustering is applied to segment the input images. Then, MapReduce is used to reducethe runtime with the guarantee of quality. To convert data for MapReduce processing, two new procedures are introduced, including Map_PFC and Reduce_*** formal representation and details of two these procedures are presented in thispaper. The experiments on satellite image and remote sensing image datasets aregiven to evaluate proposed model. Validity indices and time consuming are usedto compare proposed model to picture fuzzy clustering model. The values ofvalidity indices show that picture fuzzy clustering integrated to MapReduce getsbetter quality of segmentation than using picture fuzzy clustering only. Moreover,on two selected image datasets, the run time of MPFC model is much less thanthat of picture fuzzy clustering.

关键词： Remote sensing images picture fuzzy clustering image segmentation object detection MapReduce

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ALMA observations of the circumstellar envelope around EP Aqr

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Research in Astronomy and Astrophysics 2019年第3期19卷 97-110页

作者： Pham thi Tuyet Nhung Do thi Hoai Pham Tuan-Anh thibaut Le Bertre Pierre Darriulat Pham Ngoc Diep nguyen thi Phuong nguyen thi Thao Jan Martin Winters Department of Astrophysics Vietnam National Space CenterVAST LERMA UMR 8112 CNRS and Observatoire de Paris PSL Research University Graduate University of Science and Technology VAST IRAM 300 rue de la Piscine Domaine Universitaire

Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better spatial resolution than previously available. They are analysed with emphasis on the de-projection in space of the effective emissivity and flux of matter using as input a prescribed configuration of the velocity field, assumed to be radial. The data are found to display an intrinsic axisymmetry with respect to an axis making a small angle with respect to the line of sight. A broad range of wind configurations, from prolate(bipolar) to oblate(equatorial) has been studied and found to be accompanied by significant equatorial emission. Qualitatively, the effective emissivity is enhanced near the equator to produce the central narrow component observed in the Doppler velocity spectra and its dependence on star latitude generally follows that of the wind velocity with the exception of an omni-present depression near the poles. In particular, large equatorial expansion velocities produce a flared disc or a ring of effective emissivity and mass loss. The effect on the determination of the orientation of the star axis of radial velocity gradients, and possibly competing rotation and expansion in the equatorial disc, is discussed. In general,the flux of matter is found to reach a broad maximum at distances of the order of 500 AU from the *** are given that may be used to favour one wind velocity distribution over another. As a result of the improved quality of the data, a deeper understanding of the constraints imposed on morphology and kinematics has been obtained.

关键词： stars: AGB and post-AGB (stars:) circumstellar matter stars: individual: EP Aqr stars:mass-loss radio lines: stars

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Solutal Convection of Liquid Al-3.5 wt%Li during Its Upward Solidification

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Chinese Physics Letters 2016年第6期33卷 53-56页

作者：赵思诚刘秋生 Henri nguyen-thi Bernard Billia Department of Mechanics School of Civil EngineeringBeijing Jiaotong University Jiangsu Key Laboratory of Engineering Mechanics Southeast University Key Laboratory of Microgravity Institute of MechanicsChinese Academy of Sciences IM2NP UMR CNRS 6137Universite d'Aix-Marseille

The onset of solutal convection during the directional solidification of Bridgman type of liquid Al-3.5 wt%Li is studied. Based on the analysis of a liquid-inhomogeneous-porous-double-layer system, a bimodal feature of neutral stability curve is found. The pulling rate is ascertained as the governing parameter for the mode transition, i.e., it determines whether the microstructure in the mushy layer is related to convection after the system destabilizes.

关键词： in it of is mode for Li Al

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Forecasting Damage Mechanics By Deep Learning

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Computers, Materials & Continua 2019年第9期61卷 951-977页

作者： Duyen Le Hien nguyen Dieu thi Thanh Do Jaehong Lee Timon Rabczuk Hung nguyen-Xuan CIRTech Institute Ho Chi Minh City University of Technology(HUTECH)Ho Chi Minh CityVietnam Department of Architectural Engineering Sejong University209 Neungdong-roGwangjin-guSeoulKorea Institute of Structural Mechanics Bauhaus-Universität Weimar99423WeimarGermany Department of Physical Therapy Graduate Institute of Rehabilitation ScienceChina Medical UniversityTaichung40402Taiwan

We in this paper exploit time series algorithm based deep learning in forecasting damage mechanics *** methodologies that are able to work accurately for less computational and resolving attempts are a significant demand *** on learning an amount of information from given data,the long short-term memory(LSTM)method and multi-layer neural networks(MNN)method are applied to predict *** examples are implemented for predicting fracture growth rates of L-shape concrete specimen under load ratio,single-edge-notched beam forced by 4-point shear and hydraulic fracturing in permeable porous media problems such as storage-toughness fracture regime and fracture-height growth in Marcellus *** predicted results by deep learning algorithms are well-agreed with experimental data.

关键词： Damage mechanics time series forecasting deep learning long short-term memory multi-layer neural networks hydraulic fracturing

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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

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