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Electrochemical detection of dopamine with poly-glutamic acid patterned carbon nanotube electrodes
Minh-Phuong Ngoc Bui,Cheng Ai Li,성기훈 한국바이오칩학회 2012 BioChip Journal Vol.6 No.2
We selectively detected dopamine using poly-glutamic acid patterned single-walled carbon nanotube (PGA-SWCNT) films. Glutamic acid was electropolymerized on the surfaces of SWCNT films by repeated potential scanning, and the resulting sensor electrodes were used to detect dopamine in the presence of ascorbic acid and uric acid. Field emission scanning electron microscopy images characterizing SWCNT and PGA-SWCNT film electrodes showed a uniform carbon nanotube layer with homogeneous island clusters of PGA on the SWCNT film electrode. Cyclic voltammetry studies indicated that dopamine underwent two-electron, two-proton electrochemical oxidation at the PGA-SWCNT film that pH dependent. Different pulse voltammetry for dopamine oxidation at the PGA-SWCNT film electrode yielded a welldefined oxidation peak at 0.140V(vs. a saturated calomel electrode) in 0.1 M PBS buffer (pH 7.2). Dopamine detection was linear in the range of 3.3 to 26.6 μM(R2 =0.994) and the limit of detection was estimated to be 0.38 μM. The proposed sensor is stable and reproducible with relative standard deviations of 2.58% and 0.98-3.45%, respectively. The PGA-SWCNT film electrode also exhibited high selectivity for dopamine in the presence of interfering ascorbic acid and uric acid.
Epigenetic regulation of hypoxia inducible factor in diseases and therapeutics
Minh-Phuong Nguyen,이상규,이유미 대한약학회 2013 Archives of Pharmacal Research Vol.36 No.3
Hypoxia-inducible factors (HIFs) are masterregulators of angiogenesis and cellular adaptation in hypoxicmicroenvironments. Accumulating evidence indicatesthat HIFs also regulate cell survival, glucose metabolism,microenvironmental remodeling, cancer metastasis, andtumor progression, and thus, HIFs are viewed as therapeutictargets in many diseases. Epigenetic changes areinvolved in the switching ‘on’ and ‘off’ of many genes, andit has been suggested that the DNA hypermethylation ofspecific gene promoters, histone modifications (acetylation,phosphorylation, and methylation) and small interfering ormicro RNAs be regarded epigenetic gene targets for theregulation of disease-associated cellular changes. Furthermore,the hypoxic microenvironment is one of the mostimportant cellular stress stimuli in terms of the regulationof cellular epigenetic status via histone modification. Therefore, drug development and therapeutic approaches toischemic diseases or cancer for targeting HIFs by modulationof epigenetic status become an attractive area. Here,the authors provide a review of the literature regarding thetargeting of HIF, a key modulator of hypoxic-cell responseunder various disease conditions, by modulating histone orDNA using endogenous small RNAs or exogenouschemicals.
Technology Acceptance Model and Factors Affecting Acceptance of Social Media
Phuong Minh Binh NGUYEN,Yen Thi DO,Wann Yih WU 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.6
The main objective of this study is to investigate the consumers’ attitude and intention toward using social media by adopting the Technology Acceptance Model (TAM). This study further develops a comprehensive framework by identifying Knowledge Sharing Factors and Social Influence Factors as moderating variables that influence the relationship of attitude and behavior intention toward using social media. Based on the literature review, a research framework questionnaire is developed and conducted to test the research hypothesis in this study. The questionnaire survey method is employed to collect data from relevant social media, whereby 309 valid responses are used in the analysis. The results reveal that three TAM factors, namely, the impact of perceived usefulness, perceived ease of use, and perceived enjoyment are indeed the antecedents of attitude and behavior intention toward social media adoption. Also, the results indicate that social influence factors (social networking, social norms, and social trusts) and knowledge sharing factors (altruism, expected reciprocal benefit, and expected relationships) have moderating effect on the relationship between attitude and behavior intention toward social media. This research provides a comprehensive framework as important reference for professionals to develop social media marketing plan as well for academicians to conduct further validation.
Line Impedance Estimation Based Adaptive Droop Control Method for Parallel Inverters
Phuong Minh Le,Xuan Hoa Thi Pham,Huy Minh Nguyen,Duc Duy Vo Hoang,Tuyen Dinh Nguyen,Dieu Ngoc Vo 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1
This paper presents a new load sharing control for use between paralleled three-phase inverters in an islanded microgrid based on the online line impedance estimation by the use of a Kalman filter. In this study, the mismatch of power sharing when the line impedance changes due to temperature, frequency, significant differences in line parameters and the requirements of the Plug-and-Play mode for inverters connected to a microgrid has been solved. In addition, this paper also presents a new droop control method working with the line impedance that is different from the traditional droop algorithm when the line impedance is assumed to be pure resistance or pure inductance. In this paper, the line impedance estimation for parallel inverters uses the minimum square method combined with a Kalman filter. In addition, the secondary control loops are designed to restore the voltage amplitude and frequency of a microgrid by using a combined nominal value SOGI-PLL with a generalized integral block and phase lock loop to monitor the exact voltage magnitude and frequency phase at the PCC. A control model has been simulated in Matlab/Simulink with three voltage source inverters connected in parallel for different ratios of power sharing. The simulation results demonstrate the accuracy of the proposed control method.
Removing past data of dynamic objects using static Velodyne LiDAR sensor
Phuong Minh Chu,Seoungjae Cho,Sungdae Sim,Kiho Kwak,Yong Woon Park,Kyungeun Cho 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10
This paper presents a method of removing past data of dynamic objects by employing the Velodyne LiDAR sensor to accumulate points. In the first step, a fixed voxel map is created with the sensor position as the center. In the next step, we employ Bresenham’s line algorithm to create three-dimensional line segments from the sensor position to all points in the current frame. Each element in the line segment is a voxel, while each line segment is a list of voxels. Finally, past data of moving objects are removed by deleting all points obtained in the previous frames of each line segment.