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Preparation and characterization of silicone resin nanocomposite containing CdSe/ZnS quantum dots
Trung, Nguyen Ngoc,Luu, Quynh‐,Phuong,Son, Bui Thanh,Sinh, Le Hoang,Bae, Jin‐,Young Wiley Subscription Services, Inc., A Wiley Company 2012 Polymer composites Vol.33 No.10
<P><B>Abstract</B></P><P>We report the preparation of the core/shell cadmium selenide/Zinc sulfide quantum dots (CdSe/ZnS QDs)‐silicone resin nanocomposite through the solution‐mixing method, followed by thermal hydrosilylation. After dispersing QDs into Dow Corning two‐component silicone resins (OE6630A and OE6630B at 1:4 mixing ratio by weight), the resins were cured at 150°C for 1.5 h to produce QD‐silicone resin nanocomposites. The curing behavior of the silicone resins resulting from the thermal hydrosilylation was studied using differential scanning calorimetry (DSC). The properties of the QD‐silicone resin nanocomposites were investigated by ultraviolet–visible (UV–vis), fluorescence, confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA) measurements. The QDs that contain trioctylamine (TOA) as the original ligand can poison the Pt catalyst in the resins and inhibit the curing process by increasing the exothermic peak temperature, at which a lower heat of hydrosilylation is observed. Incorporating a small amount of CdSe/ZnS QDs (0.1 wt%) can greatly improve the thermal stability of the silicone resins. Moreover, CdSe/ZnS QDs tend to form clusters that are relatively homogeneously distributed in a cured silicone resin, offering good optical properties of 11.2 lm W<SUP>−1</SUP> luminous efficiency and 14.6% photoluminescence conversion efficiency (PCE) in light emitting device (LED) test. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers</P>
Design of High Strength Differential TWB to Enhance Drawability: FE Study and Optimization
Nguyen, Ngoc-Trung,Hariharan, Krishnaswamy,Barlat, Frederic,Lee, Myoung-Gyu Korean Society for Precision Engineering 2014 International Journal of Precision Engineering and Vol.15 No.11
In this study, cylindrical cup deep drawing of the high strength differential Tailor Welded Blank (TWB) consisting of Twinning-Induced Plasticity (TWIP) steel and low carbon steel (mild steel) was investigated using a finite element (FE) analysis. The strength ratio of TWIP to mild steel was about 4, which has not been investigated in previous researches. The formability of the TWB sheet was correlated to the weld-line movement and the thinning in the softer part of the TWB. From this virtual FE experiment, the inferior drawability of TWB when compared to monolithic blanks resulted from uncontrolled material flow. A modified tool design was proposed by adding the counter-punch concept to control the material flow near the weld-line. Then, the process parameters such as blank holding force, counter-punch force, friction conditions of punch-to-blank and counter-punch-to-blank were optimized using the Taguchi method. An improved tool design in combination with optimized process parameters improved the drawability of the TWB significantly.
Actuation Displacement of Unimorph Piezoelectric Actuators with External Loading
Ngoc-Trung Nguyen,윤광준,박훈철 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.I
In real applications, unimorph piezoelectric actuators always work under a certain carrying load. The center loading configuration can be found in the recent application of LIPCA (Lightweight Piezoceramic Composite Actuator) as the artificial muscle for flapping device. LIPCA is also used with tip loading configuration in our new model of MAV elevator. The loading performance of the device should be fully understood. This paper presents a study on the actuation displacement of unimorph piezoelectric actuators with two loading conditions: center loading and tip loading. The actuation displacement of loaded unimorph piezoelectric actuators is predicted by the finite element method and observed by experiments. Surprisingly, the predictions do not show the correct tendency of behavior of the device. Two typical kinds of piezoelectric unimorph actuator, LIPCA-C3 and THUNDER, are investigated numerically and experimentally. Some remarks on the observations are presented.
Nguyen Van Hung,Bui Thi Minh Nguyet,Nguyen Huu Nghi,Nguyen Minh Luon,Nguyen Ngoc Bich,Le Van Thanh Son,Nguyen Trung Kien,Dao Ngoc Nhiem,Nguyen Thanh Tuoi,Dinh Quang Khieu 대한환경공학회 2024 Environmental Engineering Research Vol.29 No.4
In the present work, ZnO/g-C₃N₄/biochar was prepared, and it was used for visible-light driven photocatalytic degradation of some colorants (methylene blue, rhodamine B, methyl orange) and some antibiotics (doxycycline, ciprofloxacin, amoxicilline). Biochar was prepared by pyrolysing Phragmites australis biomass. The ZnO/g-C₃N₄/biochar composite was synthesized with the alkaline hydrolysis method. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transition electron microscopy, energy dispersive X-ray/elemental mapping, ultraviolet-visible-diffuse reflectance spectroscopy, photoluminescence spectroscopy, nitrogen adsorption/desorption isotherms and X-ray photoelectron spectroscopy. The results show that ZnO nanoparticles with a large surface area are highly dispersed on the g-C₃N₄ particle surface and biochar. The composite exhibits superior photocatalytic degradation ability toward doxycycline, a broad-spectrum antibiotic of the tetracycline compared with individual components (ZnO or g-C₃N₄) and satisfies stability after six treatment cycles. The kinetics and degradation mechanisms of doxycyline were also addressed. In addition, the present catalyst also exhibits the photocatalytic degradation of methylene blue, rhodamine B, methyl orange, ciprofloxacin and amoxicillin in visible-light regions.
A Study on the Actuating Performance of Unimorph Piezoelectric Actuators with a Center Load
Nguyen, Ngoc Trung,Yoon, Kwang Joon Trans Tech Publications, Ltd. 2006 Key Engineering Materials Vol.326 No.-
<P>Research on piezoelectric unimorph actuators has been intensively increased during the past decade due to the wide applications of this actuator type in aerospace, vibration control, biomimetic robots, artificial muscles… Most analyses focused on the design performance with load-free actuating condition. Loading performance has not been considered adequately yet though in real application the actuators always work under certain carrying load. This paper introduces the measuring system, the experimental setup and presents the observed loading performance of the actuators with center load. Two typical kinds of piezoelectric unimorph actuator, LIPCA-C3 and THUNDER, are investigated. The numerical analyses are also conducted to illustrate the loading behavior of these devices. Some remarks and suggestions for future research activities are drawn.</P>
Nguyen Van Hieu,Le Thi Ngoc Loan,Nguyen Duc Khoang,Nguyen Tuan Minh,Do Thanh Viet,Do Cong Minh,Tran Trung,Nguyen Duc Chien 한국물리학회 2010 Current Applied Physics Vol.10 No.2
In this paper, a very simple procedure was presented for the reproducible synthesis of large-area SnO2nanowires (NWs) on a silicon substrate by evaporating Sn powders at temperatures of 700, 750, and 800 ℃. As-obtained SnO2 NWs were characterized by field emission scanning electron microscopy (FESEM),transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. They revealed that the morphology of the NWs is affected by growth temperature and the SnO2 NWs are single-crystalline tetragonal. The band gap of the NWs is in the range of 4.2–4.3 eV as determined from UV/visible absorption. The NWs show stable photoluminescence with an emission peak centered at around 620 nm at room-temperature. The sensors fabricated from the SnO2 NWs synthesized at 700 ℃ exhibited good response to LPG (liquefied petroleum gas) at an operating temperature of 400 ℃.
Strength Evaluation of AA6061-T6 Friction Stir Spot Welding
Ngoc-Trung Nguyen,Dae-Young Kim,Heon Young Kim 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
The present research aims to predict failure in friction stir spot welding (FSSW) joint of aluminum alloy 6061-T6 plates under specific loading cases using finite element method. The characteristics and dimensions of different regions of a FSSW joint including the stir zone (SZ), heat-affected zone (HAZ), thermal-mechanical affected zone (TMAZ), and base metal were obtained from literature. Then, the mechanical properties calculated from a relation between the measured hardness values and the corresponding strengths for each zone were applied to the failure prediction model. In which, the ESI-Wilkins-Kamoulakos (EWK) rupture model of the PAM-CRASH commercial software was employed to verify a simple case of the lap-shear tension test. The failure load obtained in this model showed a good agreement with the experimental value in reference. Then, the failure prediction for the other loading cases (peel-tension test specimen and cross-tension test specimen) was conducted following the same analysis procedure for the lap-shear tension test specimen.