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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.
Binh Hai Nguyen,Binh Thanh Nguyen,Hanh Van Vu,Chuc Van Nguyen,Dzung Tuan Nguyen,Loc Thai Nguyen,Thu Thi Vu,Lam Dai Tran 한국물리학회 2016 Current Applied Physics Vol.16 No.2
In this work, a lactose biosensor was developed by co-immobilizing b-galactosidase (b-Gal) and glucose oxidase (GOx) on microelectrodes pre-modified with Pt/graphene/P(1,5-DAN) for estimation of lactose in dairy products to prevent lactose intolerance. The Pt microelectrode was modified with graphene and 1,5-polydiaminonaphthalene film. Graphene was synthesized by chemical vapor deposition on copper tape and manually transferred to the electrode surface. Polymeric P(1,5-DAN) was grafted on top of the graphene film by electropolymerization. Modified surface of the electrode was characterized by Raman spectra analysis, FE-SEM, AFM and cyclic voltammetry. The results indicated that deposition graphene film on electrode surface induced considerable enhancement in current signal, over 20 times as high as the uncoated electrode surface. The developed sensor was successfully used to determine lactose in model samples with sensitivity, correlation coefficient (R2) and limit of detection (LOD) estimated to be 1.33 mA/(mgml1), 0.995 and 1.3 mg/ml, respectively. The combined graphene and conductive P(1,5-DAN) could serve as a novel sensing platform on electrochemical sensors with superior sensitivity.
Ngoc Thuy Nguyen,Nhat Thong Tran,Tan Phat Phan,Anh Thu Nguyen,My Xuyen T. Nguyen,Nguyen Ngan Nguyen,Young Ho Ko,Dai Hai Nguyen,Tran T.T. Van,DongQuy Hoang 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.108 No.-
While the efficient usage of biomass waste can significantly help in addressing environmental issues,there are only a few reports that discuss about processing such waste effectively at a low-cost. Such challengearises from the strong association between the components biomass. In this study, an abundantagricultural byproduct, rice husk (RH), was used as the starting resource. A simple biorefining processof alkaline peroxide treatment followed by acid precipitation and ethanol extraction was performed onRH to obtain cellulose, hemicellulose, lignin, and silica. The chemical structures, morphologies, andphysic-chemical properties of the separated components were identified through a wide range of characterizationapproaches. The final products obtained from of this process were (i) bundles of fiber-likecellulose with a fiber width of 6 mm and (ii) small particles of hemicellulose and lignin with nonuniformshapes. The lignocelluloses products had over 90 wt% carbon with 52.28% crystalline ratio. Meanwhile, the other products comprising hemicelluloses, lignin, and silica were amorphous. The outcomeof this study contributes to expanding and developing the simple and efficient conversion processof biomass waste into sustainable value-added materials. It is crucial to reduce the environmental impactby using renewable materials as the new building block resources for synthetic chemicals.
Van Tu Nguyen,Xuan Dai Nguyen 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.3
Describing the nonlinear behaviour of constitutive materials plays an important role in structural analysis. The Giuff rè– Menegotto–Pinto (GMP) model is widely used in the nonlinear modelling of steel structures, with its constituent parameters often calibrated from tests. However, the experimental results obtained require intermediate identifi cation procedures before being used directly, meanwhile, the calibration of model parameters based on experimental data is complicated due to the many interrelated constituent variables. This paper aims to propose a method that calibrates the GMP model parameters optimally based on the experimental data. An available set of test results of high-strength steels subjected to cyclic strain is employed to perform an optimal analysis. The obtained results are then compared to numerical and experimental results to evaluate the eff ectiveness of the proposed method. An extensive study was carried out to evaluate the applicability of the optimal parameters obtained and those suggested by OpenSees. The fi ndings reveal that the proposed procedure is highly effi cient, making it a useful option for developing OpenSees applications that automatically calibrate model parameters. A typical 3D steel frame structure subjected to an earthquake is analyzed to evaluate the applicability of the results obtained.
Relaxor characteristics of PSLZT-BMT-based ferroelectric material ceramics
Nguyen Van Thinh,Le Dai Vuong,Do Viet On,Truong Van Chuong,Le Vu Truong Son,Trinh Ngoc Dat,Le Van Thanh Son,Vo Thanh Tung 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3
(1-x)[(Pb0.94Sr0.05La0.01)(Zr0.54Ti0.46)0.9975O3]-x[Bi(Mn1/2Ti1/2)O3] (PSLZT-BMT) ferroelectric material ceramics with x in therange of 0-0.05 mol were successfully synthesized following the conventional solid-phase route. The materials were thoroughlyinvestigated to study their structural phase, microstructure, ferro-piezoelectric characteristics, and dielectric behavior. Theexperimental results show that the density of the samples decreased from 7.75 to 7.58 g/cm3, and the relative density decreasedin the range of 98.48%-96.28%. However, with increasing contents of BMT, the dielectric and ferroelectric properties ofPSLZT-BMT ceramics tend to decrease, specifically the maximum dielectric constant (εmax) of PSLZT-BMT decreased in therange of 23579-9991 and the residual polarization (Pr) decreases in the range of 22.54-7.87 μC/cm2 when the doping contentincreased in the range of 0.0-0.05 mol. The diffusivity values (γ) of the PSLZT-BMT material are 1.74, 1.78, 1.82, 1.84, 1.79,and 1.77 when the doping content x varies as 0.0, 0.01, 0.02, 0.03, 0.04, and 0.05 mol, respectively, which is characteristic ofrelaxor ferroelectric materials. Besides, the Tm, TB, TC-W, and C values depend on BMT concentration, and the trend decreases.
Impacts of Foreign Direct Investment on Human Capital in ASEAN
Hoi Van NGUYEN,Thuy Thi Thu NGUYEN,Tha Hien TO,Duong Quy DANG,Trang Thi Dai Luong 한국유통과학회 2020 유통과학연구 Vol.18 No.9
Purpose: Research and development of human capital in countries bring sustainable development to the nations. Especially for developing countries, the attraction of foreign direct investment not only brings economic growth to the country but also contributes to improving human capital. This study aims to assess the impact of foreign direct investment on human capital in ASEAN countries. Research design, data and methodology: With data collected from ASEAN countries from 1990 to 2019, panel data analysis is performed with revised model types (the Pooled OLS, Fixed effect model, Random effect model and regression with Driscoll-Kraay standard errors). Result: The results of the regression analysis show that FDI has a positive impact on human capital. At the same time, the study also found that public investment in education also positively affects human capital; the life expectancy factor does not affect human capital. Conclusions: With this research result, the authors also proposed a number of solutions to improve human capital by attracting FDI and improving the efficiency of investment for the education of ASEAN countries. Besides, public expenditure on education also plays an important role in raising human capital. Therefore, investment in education should be promoted further in the future.
Vo Minh Hoang Do,Long Giang Bach,Diem-Huong Nguyen Tran,Van Du Cao,Thi Nhu Quynh Nguyen,Duc Thuan Hoang,Van Cuong Ngo,Dai Hai Nguyen,Thai Thanh Hoang Thi 한국생물공학회 2020 Biotechnology and Bioprocess Engineering Vol.25 No.2
Polyamidoamine (PAMAM) dendrimer is emerging as an effective nanocarrier for delivering anticancer drugs. Still, unmodified PAMAM dendrimer is hardly used in vivo because of unsatisfied drug release, high tendency of interfering with cellular membranes, and rapid clearance by reticuloendothelial system. In this study, low generation polyamidoamine (PAMAM) dendrimer G3.0 is developed and surface modified with methoxypolyethylene glycol (PAMAM G3.0-mPEG) to overcome its limitations. Specifically, PAMAM G3.0 conjugated with mPEG at different ratios are investigated to effectively eliminate its charge-associated toxicity, in which PAMAM G3.0-mPEG- 8 is chosen for oxaliplatin (OX) loading. Results reveal that OX-loaded PAMAM G3.0-mPEG-8 has desirable size, good entrapment efficiency, and sustained release with minimum drug leakage. In addition, Resazurin assay indicates that the toxicity of loaded OX is reduced as compared to free drug but still maintain substantially anticancer activity on HeLa cells, suggesting the potential application of PAMAM G3.0-mPEG-8 for OX delivery in cancer therapy.
A new yellow Camellia (Theaceae) from central Vietnam
Dai Ngoc Do,Dung Van Luong,Chinh Duy Nguyen,Son Thanh Hoang,Huong Thi Le,한정은,박한솔 한국식물분류학회 2019 식물 분류학회지 Vol.49 No.1
Camellia pukhangensis (Theaceae), a new species with yellow flowers from Quy Hop District, Nghe An Province, Vietnam, is described and illustrated. Camellia pukhangensis has nearly sessile leaves with an attenuate to cau- date apex, cordate base, hirsute abaxial surface, hirsute adaxial midrib, hirsute petiole, deltate to ovate perules hairy on the outer surface, bright yellow orbicular to obovate petals hairy on the outer surface, androecium pubescent to two-thirds from the base, pubescent ovoid ovary with three (or four) locules and three (or four) pubescent styles free to the base. The morphological data support the provisional placement of C. pukhangensis in Camellia sect. Archecamellia Sealy.