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| 1 | Upconversion luminescence of Gd2O3:Er3+and Gd2O3:Er3+/silica nanophosphors fabricated by EDTA combustion method显示文摘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 min.The 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 investigated.The PL of Gd2O3:Er^3+nanomaterials are shown in visible at 545,594,623,648,688 nm under excitation at 275 nm.The 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 nm.The influence of excitation power at 980 nm for transitions were measured and calculated.The results indicate that the upconversion process of Gd2O3:Er^3+/silica is two photons absorption mechanism.The 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. | 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 | 2019 | Journal of Rare Earths2019，37，11： | 2 |
| 2 | Ecoregional variations of aboveground biomass and stand structure in evergreen broadleaved forests显示文摘Biotic and abiotic factors control aboveground biomass(AGB)and the structure of forest ecosystems.This study analyses the variation of AGB and stand structure of evergreen broadleaved forests among six ecoregions of Vietnam.A data set of 1731-ha plots from 52 locations in undisturbed old-growth forests was developed.The results indicate that basal area and AGB are closely correlated with annual precipitation,but not with annual temperature,evaporation or hours of sunshine.Basal area and AGB are positively correlated with trees>30 cm DBH.Most areas surveyed(52.6%)in these old-growth forests had AGB of 100–200 Mg ha^-1;5.2%had AGB of 400–500 Mg ha^-1,and 0.6%had AGB of>800 Mg ha^-1.Seventy percent of the areas surveyed had stand densities of 300–600 ind.ha^-1,and 64%had basal areas of 20–40 m^2 ha^-1.Precipitation is an important factor influencing the AGB of old-growth,evergreen broadleaved forests in Vietnam.Disturbances causing the loss of large-diameter trees(e.g.,>100 cm DBH)affects AGB but may not seriously affect stand density. | Tran Van Do Mamoru Yamamoto Osamu Kozan Vo Dai Hai Phung Dinh Trung Nguyen Toan Thang Lai Thanh Hai Vu Thanh Nam Trieu Thai Hung Hoang Van Thang Tran Duc Manh Cao Chi Khiem Vu Tien Lam Nguyen Quang Hung Tran Hoang Quy Pham Quang Tuyen Trinh Ngoc Bon Nguyen Thi Thu Phuong Ninh Viet Khuong Nguyen Van Tuan Dang Thi Hai Ha Tran Hai Long Dang Van Thuyet Dang Thinh Trieu Nguyen Van Thinh Tran Anh Hai Duong Quang Trung Nguyen Van Bich Dinh Hai Dang Pham Tien Dung Nguyen Huy Hoang Le Thi Hanh Phan Minh Quang Nguyen Thi Thuy Huong Hoang Thanh Son Nguyen Thanh Son Nguyen Thi Van Anh Nguyen Thi Hoai Anh Pham Dinh Sam Hoang Thi Nhung Hoang Van Thanh Nguyen Huu Thinh Tran Hong Van Ho Trung Luong Bui Kieu Hung | 2020 | Journal of Forestry Research2020，31，5： | 1 |
| 3 | Contamination of groundwater and risk assessment for arsenic exposure in Ha Nam province,Vietnam显示文摘 | Van Anh Nguyen Sunbaek Bang Pham Hung Viet | 2009 | Environment International2009，35，： | 1 |
| 4 | Compensation of Zn substitution and secondary phase controls effective mass and weighted mobility in In and Ga co-doped ZnO material显示文摘Conductivity s and thermal conductivity k are directly related to carrier concentration while Seebeck coefficient S is inversely proportional to carrier concentration.Therefore,improving thermoelectric(TE)performance is challenging.Here,the first-time analysis of secondary phase-controlled TE performance in terms of density-of-state effective mass m*d,weighted mobility mw and quality factor B is discussed in ZnO system.The results show that the secondary spinel phase Ga2O_(3)(ZnO)9 not only impacts on k but also on s and S at high temperature,while the effect of carrier concentration seem to be dominant at low temperature.For the high-spinel-segregation sample,a compensation of dopant atoms from the spinel to substitutional sites in the ZnO matrix at high temperature leads to a low decreased rate of temperaturedependent m*d.The compensation process also induces a band sharpening,a small mw reduction,and a large B enhancement.As a result,In and Ga co-doped ZnO bulk with the highest spinel segregation achieves the greatest PF improvement by 112.8%,owing to enhanced Seebeck coefficient by 110%as compared to the good Zn-substitution sample. | Oanh Kieu Truong Le Anh Tuan Thanh Pham Ngoc Kim Pham Trang Huyen Cao Pham Truong Huu Nguyen Dung Van Hoang Hanh Kieu Thi Ta Dai Cao Truong Hoa Thi Lai Thuy Dieu Thi Ung Vinh Cao Tran Thang Bach Phan | 2021 | Journal of Materiomics2021，7，4： | 0 |
| 5 | First Records of Megophrys daweimontis Rao and Yang, 1997 and Amolops vitreus(Bain, Stuart and Orlov, 2006)(Anura: Megophryidae, Ranidae) from Vietnam显示文摘Two amphibian species, Megophrys daweimontis and Amolops vitreus, are recorded for the first time from Vietnam, on the basis of a new amphibian collection from Dien Bien and Son La provinces. In addition, acoustic analysis of A. vitreus is also provided based on the advertisement calls recorded in Muong Nhe Nature Reserve of Dien Bien Province, Vietnam. | Dzung Trung LE Anh Van PHAM Son Hung Lan NGUYEN Thomas ZIEGLER Truong Quang NGUYEN | 2015 | Asian Herpetological Research2015，6，1： | 0 |
| 6 | Applied Biofloc Technology for Target Species in the Mekong Delta in Vietnam: A Review显示文摘 | Nguyen Van Hoa Ta Van Phuong Tran Ngoc Hai Chau Tai Tao Le Quoc Viet Nguyen Thi Hong Van Huynh Thanh Toi Tran Huu Le Vo Nam Son Pham Quoc Anh Duy | 2017 | Journal of Environmental Science and Engineering(B)2017，6，4： | 0 |
| 7 | Deep learning long short-term memory combined with discrete element method for porosity prediction in gravel-bed rivers显示文摘The porosity of gravel riverbed material often is an essential parameter to estimate the sediment transport rate,groundwater-river flow interaction,river ecosystem,and fluvial geomorphology.Current methods of porosity estimation are time-consuming in simulation.To evaluate the relation between porosity and grain size distribution(GSD),this study proposed a hybrid model of deep learning Long Short-Term Memory(LSTM)combined with the Discrete Element Method(DEM).The DEM is applied to model the packing pattern of gravel-bed structure and fine sediment infiltration processes in threedimensional(3D)space.The combined approaches for porosity calculation enable the porosity to be determined through real time images,fast labeling to be applied,and validation to be done.DEM outputs based on the porosity dataset were utilized to develop the deep learning LSTM model for predicting bed porosity based on the GSD.The simulation results validated with the experimental data then segregated into 800 cross sections along the vertical direction of gravel pack.Two DEM packing cases,i.e.,clogging and penetration are tested to predict the porosity.The LSTM model performance measures for porosity estimation along the z-direction are the coefficient of determination(R^(2)),root mean squared error(RMSE),and mean absolute error(MAE)with values of 0.99,0.01,and 0.01 respectively,which is better than the values obtained for the Clogging case which are 0.71,0.14,and 0.03,respectively.The use of the LSTM in combination with the DEM model yields satisfactory results in a less complex gravel pack DEM setup,suggesting that it could be a viable alternative to minimize the simulation time and provide a robust tool for gravel riverbed porosity prediction.The simulated results showed that the hybrid model of the LSTM combined with the DEM is reliable and accurate in porosity prediction in gravel-bed river test samples. | Duong Tran Anh Ahad Hasan Tanim Daniel Prakash Kushwaha Quoc Bao Pham Van Hieu Bui | 2023 | International Journal of Sediment Research2023，38，1： | 0 |
| 8 | Gravitationally lensed extended sources: the case of QSO RXJ0911显示文摘After a brief reminder of the mechanism of gravitational lensing of extended sources, the particular case of the host galaxy of QSO RXJ0911, a high redshift (z~2.8) quadruply imaged quasar, is explored. The non linearity of the problem, together with the proximity of the source to a cusp of the lens inner caustic, has important consequences on the dependence of the image appearance on the size and shape of the source. Their expected main features and their interpretation in terms of source extension and shape are investigated in a spirit of simplicity and in preparation for the analysis of high sensitivity and spatial resolution images that will soon be within reach with the completion of the Atacama Large Millimeter/submillimeter Array (ALMA). In particular, the information on source size carried by relative image brightness is discussed. Extension of the results to other types of quadruply imaged quasars is briefly considered. | Do Thi Hoai Pham Tuyet Nhung Pham Tuan Anh Frederic Boone Pierre Darriulat Pham Ngoc Diep Pham Ngoc Dong Nguyen Van Hiep Nguyen Thi Thao | 2013 | Research in Astronomy and Astrophysics2013，13，7： | 0 |
| 9 | STRONG CONVERGENCE OF AN INERTIAL EXTRAGRADIENT METHOD WITH AN ADAPTIVE NONDECREASING STEP SIZE FOR SOLVING VARIATIONAL INEQUALITIES显示文摘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 problem.Our 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 assumptions.Finally,we give some numerical experiments illustrating the performance of the proposed method for variational inequality problems. | Nguyen Xuan LINH Duong Viet THONG Prasit CHOLAMJIAK Pham Anh TUAN Luong Van LONG | 2022 | Acta Mathematica Scientia2022，42，2： | 0 |
| 10 | Hybrid model to optimize object-based land cover classification by meta-heuristic algorithm:an example for supporting urban management in Ha Noi,Viet Nam显示文摘This study proposed a novel object-based hybrid classification model named GMNN that combines Grasshopper Optimization Algorithm(GOA)and the multiple-class Neural network(MNN)for urban pattern detection in Hanoi,Vietnam.Four bands of SPOT 7 image and derivable NDVI,NDWI were used to generate image segments with associated attributes by PCI Geomatics software.These segments were classified into four urban surface types(namely water,impervious surface,vegetation and bare soil)by the proposed model.Alternatively,three training and validation datasets of different sizes were used to verify the robustness of this model.For all tests,the overall accuracies of the classification were approximately 87%,and the Area under Receiver Operating Characteristic curves for each land cover type was 0.97.Also,the performance of this model was examined by comparing several statistical indicators with common benchmark classifiers.The results showed that GMNN out-performed established methods in all comparable indicators.These results suggested that our hybrid model was successfully deployed in the study area and could be used as an alternative classification method for urban land cover studies.In a broader sense,classification methods will be enriched with the active and fast-growing contribution of metaheuristic algorithms. | Quang-Thanh Bui Manh Pham Van Nguyen Thi Thuy Hang Quoc-Huy Nguyen Nguyen Xuan Linh Pham Minh Hai Tran Anh Tuan Pham Van Cu | 2019 | International Journal of Digital Earth2019，12，10： | 0 |
| 11 | Embryonic, genetic and clinical outcomes of fresh versus vitrified oocyte: A retrospective cohort study显示文摘Objective:To compare embryonic development,ploidy status and clinical outcomes between fresh and frozen-thawed oocytes.Methods:This retrospective cohort study evaluated 83 fertilization cycles including both fresh and frozen oocytes from 79 patients at the HP Fertility Center of Hai Phong International Hospital of Obstetrics and Pediatrics in Vietnam.The patient underwent several ovarian stimulation cycles to accumulate a certain number of oocytes that would be vitrified.In the last oocyte retrieval,all patient’s oocytes including both frozen and fresh would be fertilized.The outcomes included the rates of oocyte survival,cleavage embryo,blastocyst,ploidy status,pregnancy,biochemical pregnancy and clinical pregnancy.Results:The oocyte survival rate after thawing was 96.5%.No statistically significant difference was found when comparing fresh and frozen oocytes regarding fertilization rate(78.1%vs.75.5%,P=0.461),usable cleavage embryo rate(86.9%vs.87.2%,P=0.916)but usable blastocyst rate was found higher statistically in the frozen oocyte group(44.4%vs.54.0%,P=0.049).The percentages of euploid,aneuploid and mosaic embryos between the fresh group and the vitrified group had no significant differences(33.8%vs.31.6%,P=0.682;51.0%vs.54.2%,P=0.569;15.2%vs.12.4%,P=0.787;respectively).The rates of pregnancy,biochemical pregnancy and clinical pregnancy had no statistical difference(68.8%vs.64.8%,P=0.764;12.5%vs.3.6%,P=0.258;37.5%vs.46.4%,P=0.565).17 Mature oocytes are the minimum to have at least one euploid embryo.Conclusions:Oocyte vitrification does not affect embryonic,genetic and clinical results.The number of mature oocytes should be considered for fertilization in some cases. | Phuong Dao Thi Son Dang Truong Thuan Nguyen Duc Anh Pham Van Anh Do Tuan Van Hanh Nguyen | 2023 | Asian pacific Journal of Reproduction2023，12，6： | 0 |
| 12 | Hydrogen roles approaching ideal electrical and optical properties for undoped and Al doped ZnO thin films显示文摘This paper distinguished hydrogen roles to improve electron mobility and carrier concentration in ZnO and Al doped ZnO sputtered films.By 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 before.Introducing 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 film.First principles calculations confirmed hydrogen substitutional stability for oxygen vacancy,significantly reducing electron conductivity effective mass and hence increasing electron mobility.In 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 film.These values approach ideal electrical and optical properties for transparent conducting oxide films.The 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. | 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 | 2022 | Journal of Materiomics2022，8，1： | 0 |
| 13 | Development and Application of a Distributed Conceptual Hydrological Model to Simulate Runoff in the Be River Basin and the Water Transfer Capacity to the Saigon River Basin,Vietnam显示文摘A distributed conceptual model(FRASC(Flow Routed Accumulation Simulation in a Catchment))has been developed,in which a rainfall-runoff module is modified from an original lumped conceptual model(Xinanjiang)via a GIS(Geographic Information System)-aided approach and a water allocation module contains reservoirs,water users and hydropower plants.The model is relatively easy to use and can easily obtain input data,but still has the ability to generate hydrological information at many points within a catchment.The model application to the Be River basin is evaluated and shows to be reliable in terms of close agreements between simulated and observed series.Daily natural flow rates for 36 years are simulated at 7,981 grid cells within a studied area of 7,650 km^2.Based on this simulated database,design discharges are predicted in various probabilities.Finally,the research determines that the water transfer capacity from the Be River basin to the Saigon River basin reaches 14%,18% and 23% of a planned value of 75 m^3/s during the dry period in a wet year(P10%),average year(P50%)and dry year(P90%),respectively. | Vu Van Nghi Ha Bui Nguyen Lam Tai Pham Anh Can Thu Van | 2020 | Journal of Environmental Science and Engineering(A)2020，9，1： | 0 |
| 14 | Building 3D CityGML models of mining industrial structures using integrated UAV and TLS point clouds显示文摘Mining industrial areas with anthropogenic engineering structures are one of the most distinctive features of the real world.3D models of the real world have been increasingly popular with numerous applications,such as digital twins and smart factory management.In this study,3D models of mining engineering structures were built based on the CityGML standard.For collecting spatial data,the two most popular geospatial technologies,namely UAV-SfM and TLS were employed.The accuracy of the UAV survey was at the centimeter level,and it satisfied the absolute positional accuracy requirement of creat-ing all levels of detail(LoD)according to the CityGML standard.Therefore,the UAV-SfM point cloud dataset was used to build LoD 2 models.In addition,the comparison between the UAV-SfM and TLS sub-clouds of facades and roofs indicates that the UAV-SfM and TLS point clouds of these objects are highly consistent,therefore,point clouds with a higher level of detail and accuracy provided by the integration of UAV-SfM and TLS were used to build LoD 3 models.The resulting 3D CityGML models include 39 buildings at LoD 2,and two mine shafts with hoistrooms,headframes,and sheave wheels at LoD3. | Canh Le Van Cuong Xuan Cao Anh Ngoc Nguyen Chung Van Pham Long Quoc Nguyen | 2023 | International Journal of Coal Science & Technology2023，10，5： | 0 |
| 15 | Rapid and efficient characterization of cervical collagen orientation using linearly polarized colposcopic images显示文摘Collagen provides tissue strength and structural integrity.Quanti fication of the orientated dispersion of collagen fibers is an important factor when studying the mechanical properties of the cervix.In this study,for the first time,a new method for rapid characterization of the collagen fiber orientations of the cervix using linearly polarized light colposcopy is presented.A total of 24 colposcopic images were captured using a cross-polarized imaging system with white LED light sources.In the preprocessing stage,the Red channel of the RGB image was chosen,which contains no information of the blood vessels because of the low-absorption of blood cells in the red region.OrientationJ,which is an ImageJ plug-in,was used to estimate the local orientation of the collagen fibers.The result shows that in the nonpregnant cervix,the middle zone(Zone 2)has circumferentially aligned collagen fibers while the inner zone(Zone 1)has randomly arranged.The collagen fiber dispersion in Zone 2 is much smaller than that in Zone 1 at all four quadrants region(anterior,posterior,left,and right quadrant).This new analysis technique could potentially combine with diagnostic tools to provide a quantitative platform of collagen fibers in the clinic. | Cat Phan Ngoc Khuong Dung Nguyen Huu Quang Hai Pham Thanh Long Nguyen Quynh Nguyen Ngoc Duc Le Huynh Tien Tran Van Tu Ly Anh | 2023 | Journal of Innovative Optical Health Sciences2023，16，5： | 0 |
| 16 | Predicting soil erosion hazard in Lattakia Governorate (W Syria)显示文摘The main objective of this study is to predict soil erosion in the Lattakia Governorate(WSyria)using the Water Erosion Prediction Project model(WEPP)and to compare the result with that of the RUSLE.Field survey and data collection were carried out,and 44 soil samples were analyzed.In addition,all the necessary input files were prepared for use in the WEPP model and RUSLE.Results show that more than of 80%of the locations studied experience slight to moderate erosion(less than 5 t/ha/y),whereas the rest of the locations experience severe soil erosion hazard.Moreover,the volume of runoff estimated by the WEPP model is in the range of 51e321 mm,and the R^2 between the simulated soil erosion and the predicted runoff reached 0.68.Interestingly,the R^2 between the WEPP model and RUSLE is 0.56,which indicates a good correlation between the two models. | Mohammed Safwan Khallouf Alaa Alshiehabi Omran Bao Pham Quoc Thi Thuy Linh Nguyen Nam Thai Van Tran Anh Duong Harsányi Endre | 2021 | International Journal of Sediment Research2021，36，2： | 0 |
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