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Bien Hoa, Vietnam

Nguyen L.T.L.,HCMC University of Technology | Nguyen C.V.,Lac Hong University | Dang G.H.,HCMC University of Technology | Le K.K.A.,HCMC University of Technology | Phan N.T.S.,HCMC University of Technology
Journal of Molecular Catalysis A: Chemical | Year: 2011

A highly porous metal-organic framework (IRMOF-8) was synthesized by a solvothermal method, and used as an efficient heterogeneous catalyst for the Friedel-Crafts acylation reaction. The solid catalyst was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), atomic absorption spectrophotometry (AAS), and nitrogen physisorption measurements. High conversions were achieved in the presence of a catalytic amount of the IRMOF-8 (1-5 mol%) without the need for an inert atmosphere. The solid catalyst could be facilely separated from the reaction mixture by simple centrifugation, and could be reused without a significant degradation in catalytic activity. No contribution from homogeneous catalysis of active acid species leaching into the reaction solution was detected. © 2011 Elsevier B.V. All rights reserved. Source

Manh H.D.,Lac Hong University
Scientometrics | Year: 2015

This paper investigates Vietnam’s scientific publications between 1996 and 2013 from Scopus database, focusing on international collaboration. The total scientific output of the country increased about 16 publications per year during 1996–2001 and quickly increased 20 % per year during 2002–2013. However, the share of international collaboration was about 77 % of the total output. Biological and agricultural science, medicine dominated the total output, but 80–90 % of these publications are from international collaboration. In contrast, mathematics is the only field that domestic output is larger than collaboration output. Japan is the largest collaborating country, followed by United States, France, South Korea and United Kingdom. Analyzing titles of publications with these collaborating countries, we found high frequency of “Vietnam” or “Vietnamese” words. This result suggested that many study subjects of these research collaborations were from Vietnam. Furthermore, corresponding authors of these research collaborations are mainly from collaborating countries, which suggested that these research collaborations mainly led by foreign authors. Although the total output was quickly increased, especially collaboration output, Vietnamese researchers should be aware about their low contribution to these collaborations. © 2015 Akadémiai Kiadó, Budapest, Hungary Source

Tran L.B.,Lac Hong University | Le T.H.,Ho Chi Minh City University of Technology
Proceedings - 2015 IEEE International Conference on Knowledge and Systems Engineering, KSE 2015 | Year: 2015

In this paper, the authors propose a personal authentication system using a combination of both face and fingerprint features. In the proposed system, face and fingerprint features are extracted by Zernike Moment (ZM), the extracted features are classified by Relevance Vector Machine (RVM), the generated matching scores are fused using sum rule. Experimental results on the FVC2004 DB4 and ORL databases show that RVM provides better accuracy compared to unit face or fingerprint recognition and existing fusion algorithms. With respect to SVM fusion, it is observed that, the accuracy of RVM and SVM are comparable, however, the time for RVM fusion is significantly reduced. © 2015 IEEE. Source

Pham V.-C.,National Cheng Kung University | Pham V.-C.,Lac Hong University | Juang J.-C.,National Cheng Kung University
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2015

Abel inversion techniques have been widely employed to retrieve electron density profiles (EDPs) from radio occultation (RO) measurements, which are available by observing Global Navigation Satellite System (GNSS) satellites from low-earth-orbit (LEO) satellites. It is well known that the ordinary Abel inversion might introduce errors in the retrieval of EDPs when the spherical symmetry assumption is violated. The error, however, is case-dependent; therefore it is desirable to associate an error index or correction coefficient with respect to each retrieved EDP. Several error indices have been proposed but they only deal with electron density at the F2 peak and suffer from some drawbacks. In this paper we propose an artificial neural network (ANN) based error correction method for EDPs obtained by the ordinary Abel inversion. The ANN is first trained to learn the relationship between vertical total electron content (TEC) measurements and retrieval errors at the F2 peak, 220. km and 110. km altitudes; correction coefficients are then estimated to correct the retrieved EDPs at these three altitudes. Experiments using the NeQuick2 model and real FORMOSAT-3/COSMIC RO geometry show that the proposed method outperforms existing ones. Real incoherent scatter radar (ISR) measurements at the Jicamarca Radio Observatory and the global TEC map provided by the International GNSS Service (IGS) are also used to valid the proposed method. © 2015. Source

Cu T.S.,Vietnam Academy of Science and Technology | Cao V.D.,Lac Hong University | Nguyen C.K.,Vietnam Academy of Science and Technology | Tran N.Q.,Vietnam Academy of Science and Technology
Macromolecular Research | Year: 2014

In this paper, we report the preparation and stabilization of colloidal silver nanoparticle solution, with the assistance of chitosan dihydroxyphenyl acetamide (CDHPA), or oligochitosan dihydroxyphenyl acetamide (OCDHPA). The structure of the chitosan derivatives were characterized by nuclear magnetic resonance (1H NMR) spectroscopy. The morphology of the synthesized silver core-chitosan shell nanoparticles were observed by transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques, and showed a well-defined core-shell structure of polymer-coated silver nanoparticles (AgNPs). The core-shell NPs exhibited a strong antibacterial activity against E. coli and S. aureus, at a very low concentration of AgNPs (2.5 ppm). Our studies offer a new method for the preparation and protection of silver nanoparticles for antibacterial applications. [Figure not available: see fulltext.] © 2014 The Polymer Society of Korea and Springer Sciene+Business Media Dordrecht. Source

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