Ho Chi Minh City, Vietnam
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Cuong N.-V.,Chung Yuan Christian University | Cuong N.-V.,Ho Chi Minh University of Industry | Li Y.-L.,Chung Yuan Christian University | Hsieh M.-F.,Chung Yuan Christian University
Journal of Materials Chemistry | Year: 2012

Conventional nanocarriers are associated with systemic toxicity and poor bioavailability of the anti-tumor drugs due to undesired specificity. The objective of this study is to introduce a folic targeting ligand on the surface of a polymeric nanocarrier to enhance the delivery of the doxorubicin (DOX) via ligand-mediated endocytosis. Hence, the folate decorated-micelle based on the star-shape FOL-PEG-PCL copolymer was synthesized. The chemical structure of the copolymer was characterized by proton nuclear magnetic resonance spectroscopy, gel permeation chromatography and differential scanning calorimetry, respectively. A generalized biocompatibility test of the micelle was evaluated using MTT assay, in vitro hemolytic test, nitric oxide production and reactive oxygen species generation, respectively. When DOX was encapsulated in the micelle, the drug loading efficiency and drug loading content were found to be 90% and 13%, respectively. The average particle size of the DOX-loaded micelle, determined by dynamic light scattering was 148.2 nm. The intracellular uptake experiments showed that human breast cancer cells (MCF-7) could uptake a similar amount of DOX from two dosage forms: free DOX and DOX-loaded FOL-PEG-PCL micelle. The uptake of DOX-loaded FOL-PEG-PCL micelle was higher than that of free DOX in MCF-7/adr cells, adriamycin-resistant cell line. The uptake of the micelle in MCF-7 was found to be time-dependent; e.g. caveolae/lipid-raft mediated endocytosis and then folate receptor-mediated endocytosis was observed. This study demonstrates that the FOL-PEG-PCL micelle was non-toxic and the DOX-loaded FOL-PEG-PCL micelle could be a potential carrier for cancer treatments. © The Royal Society of Chemistry 2011.


Nguyen Q.H.,Ho Chi Minh University of Industry | Choi S.B.,Inha University
Smart Materials and Structures | Year: 2010

This paper presents an optimal design of a magnetorheological (MR) brake for a middle-sized passenger car which can replace a conventional hydraulic disc-type brake. In the optimization, the required braking torque, the temperature due to zero-field friction of MR fluid, the mass of the brake system and all significant geometric dimensions are considered. After describing the configuration, the braking torque of the proposed MR brake is derived on the basis of the field-dependent Bingham and Herschel-Bulkley rheological model of the MR fluid. The optimal design of the MR brake is then analyzed taking into account available space, mass, braking torque and steady heat generated by zero-field friction torque of the MR brake. The optimization procedure based on the finite element analysis integrated with an optimization tool is proposed to obtain optimal geometric dimensions of the MR brake. Based on the proposed procedure, optimal solutions of single and multiple disc-type MR brakes featuring different types of MR fluid are achieved. From the results, the most effective MR brake for the middle-sized passenger car is identified and some discussions on the performance improvement of the optimized MR brake are described. © 2010 IOP Publishing Ltd.


Hung N.Q.,Ho Chi Minh University of Industry | Bok C.S.,Inha University
Mechanics Based Design of Structures and Machines | Year: 2012

This research focuses on developing a new configuration and optimal design of magnetorheological (MR)-fluid-based brake (MR brake in short) for a middle-sized motorcycle that can replace conventional drum-type brake. A novel configuration featuring a T-shaped drum and a hybrid concept of magnetic circuit (using both axial and radial magnetic flux) to generate braking force is proposed for the MR brake. An optimal design of the MR brake considering the required braking torque, the temperature due to zero-field friction of MR fluid, the mass of the brake system, and all significant geometric dimensions is performed. After a brief introduction of the configuration of the proposed MR brake, the braking torque is derived based on Herschel-Bulkley rheological model of the MR fluid. The optimal design of the MR brake is then analyzed taking into account available space, mass, braking torque, and steady heat generated by zero-field friction torque of the MR brake. An optimization procedure based on the finite element analysis (FEA) integrated with an optimization tool is used to obtain optimal geometric dimensions of the MR brake. From the results, discussions on the performance improvement of the optimized MR brake are described. © 2012 Copyright Taylor and Francis Group, LLC.


Nguyen Q.H.,Ho Chi Minh University of Industry | Choi S.B.,Inha University
Smart Materials and Structures | Year: 2012

This research focuses on optimal design of different types of magnetorheological brakes (MRBs), from which an optimal selection of MRB types is identified. In the optimization, common types of MRB such as disc-type, drum-type, hybrid-types, and T-shaped type are considered. The optimization problem is to find the optimal value of significant geometric dimensions of the MRB that can produce a maximum braking torque. The MRB is constrained in a cylindrical volume of a specific radius and length. After a brief description of the configuration of MRB types, the braking torques of the MRBs are derived based on the HerschelBulkley model of the MR fluid. The optimal design of MRBs constrained in a specific cylindrical volume is then analysed. The objective of the optimization is to maximize the braking torque while the torque ratio (the ratio of maximum braking torque and the zero-field friction torque) is constrained to be greater than a certain value. A finite element analysis integrated with an optimization tool is employed to obtain optimal solutions of the MRBs. Optimal solutions of MRBs constrained in different volumes are obtained based on the proposed optimization procedure. From the results, discussions on the optimal selection of MRB types depending on constrained volumes are given.


Nguyen Q.H.,Ho Chi Minh University of Industry | Choi S.B.,Inha University
Smart Materials and Structures | Year: 2012

This work presents an optimal solution of a new type of motorcycle brake featuring different smart magnetorheological (MR) fluids. In this study, typical types of commercial MR fluid are considered there for the design of a motorcycle MR brake; MRF-122-2ED (low yield stress), MRF-132-DG (medium yield stress) and MRF-140-CG (high yield stress). As a first step, a new configuration featuring a T-shaped drum MR brake is introduced and a hybrid concept of magnetic circuit (using both axial and radial magnetic flux) to generate braking force is analyzed based on the finite element method. An optimal design of the MR brake considering the required braking torque, the temperature due to friction of the MR fluid, the mass of the brake system and all significant geometric dimensions is then performed. For the optimization, the finite element analysis (FEA) is used to achieve principal geometric dimensions of the MR brake. In addition, the size, mass and power consumption of three different MR motorcycle brakes are quantitatively analyzed and compared. © 2012 IOP Publishing Ltd.


Le T.,Ho Chi Minh University of Industry | Vo B.,Ho Chi Minh City University of Technology
Engineering Applications of Artificial Intelligence | Year: 2014

Erasable itemset (EI) mining is an interesting variation of frequent itemset mining which allows managers to carefully consider their production plans to ensure the stability of the factory. Existing algorithms for EI mining require a lot of time and memory. This paper proposes an effective algorithm, called mining erasable itemsets (MEI), which uses the divide-and-conquer strategy and the difference pidset (dPidset) concept for mining EIs fully. Some theorems for efficiently computing itemset information to reduce mining time up and memory usage are also derived. Experimental results show that MEI outperforms existing approaches in terms of both the mining time and memory usage. Moreover, the proposed algorithm is capable of mining EIs with higher thresholds than those obtained using existing approaches. © 2013 Elsevier Ltd.


Luy N.T.,Ho Chi Minh University of Industry
Conference Proceedings - IEEE International Conference on Systems, Man and Cybernetics | Year: 2012

This paper proposes a new method to design a reinforcement learning-based integrated kinematic and dynamic tracking control scheme for a nonholonomic wheeled mobile robot. The scheme uses just only one neural network to design an online adaptive synchronous policy iteration algorithm implemented as an actor critic structure. Our tuning law for the single neural network not only learns online a tracking-HJB equation to approximate both the optimal cost and the optimal adaptive control law but also guarantees closed-loop stability in real-time. The convergence and stability of the overall system are proven by Lyapunov theory. The simulation results for wheeled mobile robot verify the effectiveness of the proposed controller. © 2012 IEEE.


Quang Huy N.,Ho Chi Minh University of Industry
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010

The present work aims at studying the decrease in an HPGe p-type detector efficiency over its operation period and the influence of the dead layer thickness increase on this efficiency decreasing process. The study was conducted with the Canberra coaxial GC1518 p-type detector using MCNP5 code. It is found that the efficiency of this detector has reduced by 18.5% over its 13 years of operation, corresponding to the increase of dead layer thickness from 0.35 to 1.46 mm. The relative reduction in efficiency linearly depends on the dead layer thickness and both these parameters are linearly grown versus operation time. The increase of the dead layer thickness causes two effects influencing the decrease in efficiency. They are the additional shielding effect of increase in dead layer thickness (shielding effect) and the effect of decrease in germanium active volume (volume effect). It is found that for 59 keV gamma energy, the efficiency decrease is determined only by the shielding effect whilst the volume effect can be negligible. As for 5111332 keV gamma energies, the efficiency decrease is determined by both the volume and the shielding effects. © 2010 Elsevier B.V. All rights reserved.


Luy N.T.,Ho Chi Minh University of Industry
Proceedings - 2012 IEEE International Conference on Cyber Technology in Automation, Control, and Intelligent Systems, CYBER 2012 | Year: 2012

This paper proposes a new method to design a reinforcement learning-based integrated kinematic and dynamic tracking control scheme for a nonholonomic wheeled mobile robot. The scheme uses just only one neural network to design an online adaptive synchronous policy iteration algorithm implemented as an actor critic structure. Our tuning law for the single neural network not only learns online a tracking-HJB equation to approximate both the optimal cost and the optimal control law but also guarantees closed-loop stability in real-time. The convergence and stability of the overall system are proven by Lyapunov theory. The simulation results for wheeled mobile robot verify the effectiveness of the proposed controller.


Huy N.Q.,Ho Chi Minh University of Industry
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

The present work studies the influence of the dead-layer thickness effect on the gamma spectra of a high purity germanium (HPGe) p-type detector at two different points in time. The study was conducted with the Canberra GC1518 detector, which had a dead-layer thickness of 1.15 mm in 2005 and 1.46 mm in 2009. The measurement of gamma spectra for the reference point-like sources, 137Cs, 60Co and 22Na, indicated that the spectra in the energy region of 50170 keV measured in 2009 were higher than those measured in 2005. This result implies that, in this energy interval, the dead-layer thickness effect is observed, which can be explained by the contribution of the delayed signals. Furthermore, the measured spectra in this energy region were higher than those calculated by MCNP5 code. These findings make it possible to evaluate the contribution of delayed signals, which are proportional to the thickness of the dead layer. © 2011 Elsevier B.V. All rights reserved.

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