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Comparative study on water-soluble inorganic ions in PM2.5 from two distinct climate regions and air quality

Journal of Environmental Sciences 2020年第2期32卷 349-360页

作者： Duong huu Huy Le Tu Thanh To Thi Hien Norimichi Takenaka Faculty of Food Science and Technology Ho Chi Minh City University of Food Industry140 Le Trong Tan StreetTan Phu DistrictHo Chi Minh CityViet Nam Faculty of Environment University of ScienceVietnam National University–Ho Chi Minh City227 Nguyen Van Cu StreetDistrict 5Ho Chi Minh CityViet Nam Graduate School of Humanities and Sustainable System Sciences Osaka Prefecture University1-1 Gakuen-choNaka-kuSakai-shiOsaka 599-8531Japan

Recently, air quality has significantly improved in developed country, but that issue is of concern in emerging megacity in developing *** this study, aerosols and their precursor gas were collected by NILU filter pack at two distinct urban sites during the winter and summer in Osaka, Japan and dry and rainy seasons in Ho Chi Minh City(HCMC),*** aims are to investigate the contribution of water-soluble inorganic ions(WSIIs) to PM2.5, thermodynamic characterization and possible formation pathway of secondary inorganic aerosol(SIA).The PM2.5 concentration in Osaka(15.8 μg/m^3) is lower than that in HCMC(23.0 μg/m^3), but the concentration of WSIIs in Osaka(9.0 μg/m^3) is two times higher than that in HCMC(4.1 μg/m^3).Moreover, SIA including NH4^+, NO3^-and SO4^2-are major components in WSIIs accounting for 90% and 76%(in molar) in Osaka and HCMC,*** models were used to understand the thermodynamic characterization of urban ***, statistical analysis results indicate that very good agreement(R2> 0.8) was found for all species, except for nitrate aerosol in *** found that when the crustal species present at high amount, those compositions should be included in model calculation(*** the HCMC situation).Finally, we analyzed the characteristics of NH4^+– NO3^-– SO4^2-system.A possible pathway to produce fine nitrate aerosol in Osaka is via the homogeneous reaction between NH3 and HNO3, while nonvolatile nitrate aerosols can be formed by the heterogeneous reactions in HCMC.

关键词： Water-soluble inorganic ions Thermodynamic model PM2.5

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SOME PRELIMINARY RESULTS FROM STUDY OF CRUSTAL DEFORMATION IN VIETNAM

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大地测量与地球动力学 2003年第B12期23卷 114-118页

作者： Cao Dinh Trieu Le Van Dung nguyen huu Tuyen Pham Nam Hung Institute of Geophysics Institute of GeophysicsInstitute of GeophysicsInstitute of Geophysics 18 Hoang Quoc Viet Road Cau GiayHanoi18 Hoang Quoc Viet Road Cau GiayHanoi18 Hoang Quoc Viet Road Cau GiayHanoi18 Hoang Quoc Viet Road Cau GiayHanoi

In this work, the authors present some results of strain monitoring within the territory of Vietnam from 1984 to 2001. Data analysis shows that (1) the Phu Lien area is tectonically stable with low strain rate, 1×10\+\{-6\} /a; (2) the Hoa Binh area has indication of tectonic instability with relatively high strain rate of the earth crust: absolute value of the strain reaching 100×10\+\{-6\}, usual average strain amplitude of 60×10\+\{-6\}, whereas the monthly average strain intensity varies in a range from 30×10\+\{-6\} to 50×10\+\{-6\}; (3) there are clear indications of the strain state of the earth crust before occurrence of earthquakes of medium or higher magnitude. This is a very important indication in the research and short term prediction of earthquakes, especially for the areas with low seismic stability like the NW of Vietnam.

关键词：越南表层变形应变测量系统操作原则应变数据因变与地震相对关系地震活动特性

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High-performance carbon fiber/gold/copper composite wires for lightweight electrical cables

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Journal of Materials Science & Technology 2020年第7期42卷 46-53页

作者： Thang Q.Tran Jeremy Kong Yoong Lee Amutha Chinnappan nguyen huu Loc Long T.Tran Dongxiao Ji W.A.D.M.Jayathilaka Vishnu Vijay Kumar Seeram Ramakrishna Department of Mechanical Engineering National University of Singapore9 Engineering Drive 1EA-07-05Singapore 117575Singapore Faculty of Mechanical Engineering Ho Chi Minh City University of TechnologyVNUHCM268 Ly Thuong KietDistrict 10Ho Chi Minh City 740400Viet Nam

In this study,we synthesized high-performance Carbon Fiber/Gold/Copper(CF/Au/Cu)composite wires by using a 2-step deposition method via sputtering and *** Au was sputtered on PANbased CFs as a pre-treatment,the wettability and surface reactivity of the CFs were improved,resulting in a homogeneous deposition of Cu on their *** different Cu electrodeposition time,the resulting CF/Au/Cu composite wires could possess a high strength of up to 3.27 GPa(~10 times stronger than copper wires)while their electrical conductivity could be as high as 4.4×10^5 S/cm(~75%of that for copper).More importantly,since the composite wires were lightweight(up to 70%lower than Cu mass density),they are a promising candidate to substitute conventional heavy metal wires in the future electrical applications.

关键词： Carbon fiber Copper composite wires Strength Electrical properties

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Overview of Vietnamese Accounting System Since 1975 and the Process of Vietnam＇s Convergence to IFRS

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Journal of Modern Accounting and Auditing 2015年第5期11卷 260-268页

作者： nguyen xuan Hung University of Economics Ho Chi Minh City Vietnam

The development of accounting systems is influenced by socio-economic characteristics at each stage. The paper explores the impact of the characteristics of political institutions at every stage in the development of social economy, which determines the objects using accounting information, as well as the legal accounting system issued so that accounting can meet the demand for accounting information of these objects in Vietnam from 1975 to the present. Based on studies by authors in this period as well as issued accounting documents system, this paper aims to point out the formation and development process of Vietnam accounting system, providing researchers and elaborating agencies with a basis for determining the right development direction of Vietnam accounting in the coming time.

关键词： Vietnam accounting system accounting integration process socio-economic characteristics

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Synthesis and characterization of core/shell structured nanophosphors CePO_4:Tb@LaPO_4 by solvothermal method

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Journal of Rare Earths 2011年第12期29卷 1147-1151页

作者： Dinh xuan Loc Tran Thi Kim Chi Tran Thu Huong nguyen Vu Tran Kim Anh Wieslaw Strek Le Quoc Minh Institute of Materials Science Vietnam Academy of Science and Technology Institute of Low Temperature and Structure Research Polish Academy of Sciences(PAN) University of Engineering and Technology

Core/shell structured CePO4：Tb（Ⅲ）@LaPO4 and CePOa：Tb（Ⅲ） were successfully synthesized in tris（2-ethylhexyl） phosphate （TEHP） and diethylene glycol （DEG） solvents for comparison of the two techniques in open air and closed reaction vessel. Morphology and crystal structure of the core/shell nanophosphors were determined by using X-ray diffraction （XRD） and transmission electron microscopy （TEM）, which showed that nanophosphors had diameter of about 5-10 nm with the monoclinic monazite phase. The nanophosphors obtained by close vessel procedure showed smaller size, more homogeneity and pure crystallite. The luminescent measurements were done upon the different excitation wavelengths in ultraviolet region and at room temperatm＇e to elucidate the influences of the used solvents and the reaction temperatures. It was found that CePO4：Tb@LaPO4 preparedby the close vessel synthesis showed the intensity of green band of the transfer from 5D4 to 7F5 energy level, which was strongly increased, and the luminescent decay time was 3.2 ms, which was longer than that of naked CePO4：Tb phosphor.

关键词： solvothermal synthesis luminescence CePOn:Tb CePOa:Tb@LaPO4 rare earths

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Influence of dietary mannan oligosaccharides supplementation on fingerling clownfish, Amphiprion ocellaris (Cuvier, 1830)

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Journal of Coastal Life Medicine 2017年第8期5卷 325-329页

作者： Hoang Do-huu Trung Kien nguyen Vietnam Academy of Science&Technology(VAST)-Institute of Oceanography 01 Cau DaNha TrangVietnam

Objective: To test the effects of dietary mannan oligosaccharides (MOS) on clownfish Amphiprion ocellaris (A. ocellaris). Methods: Six levels (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 g/kg diet) of MOS were added to the basal diet (used as control diet) and fed clownfish A. ocellaris [total length (24.21 ± 0.16) mm] for 70 days. Growth performance and tissue protein were measured. Results: The result showed that growth rate was enhanced significantly in fish fed 0.10% and 0.15% MOS in diets compared to fish fed other MOS levels or control (P < 0.05). Survival rate significantly increased in fish fed diets with 0.20% and 0.25% MOS, compared to control. Fraction rates of protein growth were significantly higher in fish fed diets with 0.15%, 0.20%and 0.25% MOS supplementation than those fish fed other MOS inclusion levels and the control (P < 0.04). Dietary MOS concentrations and clownfish growth rates were significantly correlated. Optimal MOS concentration was predicted to be 0.185%, 0.173% and 0.171% at Days 14, 42 and 70, respectively. Conclusions: In conclusion, MOS-supplemented diet benefits for boosting growth, survival and body composition of the clownfish, A. ocellaris.

关键词： Amphiprion ocellaris Clownfish Mannan oligosaccharides Growth Body composition

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Sensitivity of Lagrangian Particle Tracking Based on a 3D Numerical Model

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Journal of Modern Physics 2012年第12期3卷 1972-1978页

作者： Dang huu Chung nguyen Thi Kieu Duyen Institute of Mechanics Vietnamese Academy of Science and Technology Hanoi Vietnam

The aim of the paper is to investigate in detail the sensitivity of particles displacement based on method of Lagrangian particle tracking in combination with a 3D Eulerian numerical model that was developed by the first author, namely FSUM. The characteristic parameters used for this research include the possibilities of random movement, settling velocity of solid particle, horizontal and vertical diffusion coefficients and condition of particle fixed with a constant distance under water surface. The first part is on the fluid flow model. It includes 3D Navier-Stokes equations together with the initial and boundary conditions that were numerically solved with the finite difference method and coded with FORTRAN 90/95 using parallel technique with OpenMP. A semi-Lagrangian treatment of the advective terms was used. The second part is related to Lagrangian particle tracking model and was solved with the fourth Runge-Kutta method. Model was applied for Strait of Johor and has been calibrated by using measured data on water level and velocity at one station. Eight cases of simulations with many different options were carried out. Through computed cases it shows that random term and settling velocity are very important factors for the behavior of particle trajectory. Although the random diffusion is minor in comparison with flow velocity, but it can rearrange the initial distribution of particles then the cluster of particles become more dispersive during the process of movement. In addition, introducing settling velocity of particle makes a big change on the trajectory of particle that becomes more suitable to sediment transport. The study gave a comprehensive picture on particle movement. The model also showed its possibilities of multiform applications in simulation and prediction for the different problems in practice.

关键词： 3D FSUM Model Random Walk Settling Velocity Numerical Simulations

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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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Improved flood susceptibility mapping using a best first decision tree integrated with ensemble learning techniques

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Geoscience Frontiers 2021年第3期12卷 333-342页

作者： Binh Thai Pham Abolfazl Jaafari Tran Van Phong Hoang Phan Hai Yen Tran Thi Tuyen Vu Van Luong huu Duy nguyen Hiep Van Le Loke Kok Foong University of Transport Technology Ha Noi 100000Viet Nam Research Institute of Forests and Rangelands Agricultural ResearchEducation and Extension Organization(AREEO)TehranIran Institute of Geological Sciences Vietnam Academy of Sciences and Technology84 Chua Lang StreetDong daHa NoiViet Nam Department of Geography School of Social EducationVinh UniversityViet Nam Department of Resource and Environment Management School of Agriculture and ResourcesVinh UniversityViet Nam Faculty of Geography VNU University of Science334 Nguyen TraiHa NoiViet Nam Institute of Research and Development Duy Tan UniversityDa Nang 550000Viet Nam Department for Management of Science and Technology Development Ton Duc Thang UniversityHo Chi Minh CityViet Nam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh CityViet Nam

Improving the accuracy of flood prediction and mapping is crucial for reducing damage resulting from flood *** this study,we proposed and validated three ensemble models based on the Best First Decision Tree(BFT)and the Bagging(Bagging-BFT),Decorate(Bagging-BFT),and Random Subspace(RSS-BFT)ensemble learning techniques for an improved prediction of flood susceptibility in a spatially-explicit manner.A total number of 126 historical flood events from the Nghe An Province(Vietnam)were connected to a set of 10 flood influencing factors(slope,elevation,aspect,curvature,river density,distance from rivers,flow direction,geology,soil,and land use)for generating the training and validation *** models were validated via several performance metrics that demonstrated the capability of all three ensemble models in elucidating the underlying pattern of flood occurrences within the research area and predicting the probability of future flood *** on the Area Under the receiver operating characteristic Curve(AUC),the ensemble Decorate-BFT model that achieved an AUC value of 0.989 was identified as the superior model over the RSS-BFT(AUC=0.982)and Bagging-BFT(AUC=0.967)models.A comparison between the performance of the models and the models previously reported in the literature confirmed that our ensemble models provided a reliable estimate of flood susceptibilities and their resulting susceptibility maps are trustful for flood early warning systems as well as development of mitigation plans.

关键词： Machine learning Ensemble learners Hybrid modeling

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Hydrogen roles approaching ideal electrical and optical properties for undoped and Al doped ZnO thin films

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Journal of Materiomics 2022年第1期8卷 123-135页

作者： Dung Van Hoang Nam Hoang Vu Nga Thi Do Anh Tuan Thanh Pham Truong huu nguyen Jer-Lai Kuo Thang Bach Phan Vinh Cao Tran Laboratory of Advanced Materials University of ScienceHoChiMinh City700000Viet Nam Vietnam National University HoChiMinh City700000Viet Nam HoChiMinh City Institute of Physics HoChiMinh City700000Viet Nam Institute of Atomic and Molecular Sciences Academia SinicaTaipei10617Taiwan Center for Innovative Materials and Architectures(INOMAR) HoChiMinh City700000Viet Nam Faculty of Materials Science&Technology University of ScienceHoChiMinh City700000Viet Nam

This paper distinguished hydrogen roles to improve electron mobility and carrier concentration in ZnO and Al doped ZnO sputtered *** combining experimental evidences and theoretical results,we find out that hydrogen located at oxygen vacancy sites(H_(O))is the main factor gives rise to increase simultaneously mobility and carrier concentration which has not been mentioned *** appropriate hydrogen content during sputtering not only results in crystalline relaxation but also supports doping Al into ZnO,increasing carrier concentration and electron mobility in the *** principles calculations confirmed hydrogen substitutional stability for oxygen vacancy,significantly reducing electron conductivity effective mass and hence increasing electron *** particular,0.8%hydrogen partial pressure ratio achieved 61 cm^(2)V^(-1)s^(-1)maximum electron mobility,optical transmittance above 82%in visible and near-infrared regions,and 2×10^(20) cm^(-3)carrier concentrations for H-Al co-doped ZnO *** values approach ideal electrical and optical properties for transparent conducting oxide *** presence of one maximum electron mobility was attributed to competition between increasing mobility due to restoring effective electron mass and hydrogen passivation of native defects,and decreased electron mobility due to electron-phonon scattering.

关键词： High electron mobility Hydrogen roles Passivation effects Effective electron mass DFT calculations Doped ZnO thin Film

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