Exploration of genetic diversity of Bacillus spp. from industrial shrimp ponds in Vietnam by multi-locus sequence typing

Le, Xuan The,Pham, Dung Tien,Pham, Tuan Anh,Tran, Tung Thanh,Khuat, Thanh Huu,Le, Hoa Quang,Vu, Ut Ngoc The Korean Society of Fisheries and Aquatic Scienc 2019 Fisheries and Aquatic Sciences Vol.22 No.8

Bacillus is a diverse genus consisting of more than 200 species with extensive genetic diversity. Their beneficial effects in industrial shrimp farming have been well documented. However, little is known about the biodiversity of the Bacillus spp. in this aquaculture system. Taxonomic analysis by 16S rRNA sequencing does not always allow species-level identification of Bacillus spp. In this study, 26 Bacillus isolates from two industrial Litopenaeus vannamei shrimp ponds in Bac Lieu Province, Vietnam, were analyzed for their genetic diversity by multi-locus sequence typing (MLST). A total of 22 sequence types were identified and segregated into four distinct clusters, corresponding to B. subtilis, B. velezensis, B. siamensis, and B. licheniformis. Bacillus subtilis and B. velezensis accounted for more than 73% of the Bacillus isolates. Notably, the MLST scheme exhibited high discriminatory power and might be further simplified to be a convenient method to identify species of the genus Bacillus.

Exploration of genetic diversity of Bacillus spp. from industrial shrimp ponds in Vietnam by multi-locus sequence typing

Xuan The Le,Dung Tien Pham,Tuan Anh Pham,Tung Thanh Tran,Thanh Huu Khuat,Hoa Quang Le,Ut Ngoc Vu 한국수산과학회 2019 Fisheries and Aquatic Sciences Vol.22 No.3

Bacillus is a diverse genus consisting of more than 200 species with extensive genetic diversity. Their beneficial effects in industrial shrimp farming have been well documented. However, little is known about the biodiversity of the Bacillus spp. in this aquaculture system. Taxonomic analysis by 16S rRNA sequencing does not always allow species-level identification of Bacillus spp. In this study, 26 Bacillus isolates from two industrial Litopenaeus vannamei shrimp ponds in Bac Lieu Province, Vietnam, were analyzed for their genetic diversity by multi-locus sequence typing (MLST). A total of 22 sequence types were identified and segregated into four distinct clusters, corresponding to B. subtilis, B. velezensis, B. siamensis, and B. licheniformis. Bacillus subtilis and B. velezensis accounted for more than 73% of the Bacillus isolates. Notably, the MLST scheme exhibited high discriminatory power and might be further simplified to be a convenient method to identify species of the genus Bacillus.

Enhanced electrosorption of NaCl and nickel(II) in capacitive deionization by CO2 activation coconut-shell activated carbon

Huynh Le Thanh Nguyen,Tran Thanh Nhut,Ho Thi Thanh Nguyen,Le Xuan Hoa,Le Viet Hai,Nguyen Thai Hoang 한국탄소학회 2022 Carbon Letters Vol.32 No.6

Enhancing the capacitive deionization performance requires the inner structure expansion of porous activated carbon to facilitate the charge storage and electrolyte penetration. This work aimed to modify the porosity of coconut-shell activated carbon (AC) through CO2 activation at high temperature. The electrochemical performance of CO2-activated AC electrodes was evaluated by cyclic voltammetry, charge/discharge test and electrochemical impedance spectroscopy, which exhibited that AC-800 had the superior performance with the highest capacitance of 112 F/g at the rate of 0.1 A/g and could operate for up to 4000 cycles. Furthermore, in the capacitive deionization, AC-800 showed salt removal of 9.15 mg/g with a high absorption rate of 2.8 mg/g min and Ni(II) removal of 5.32 mg/g with a rate close to 1 mg/g.min. The results promote the potential application of CO2-activated AC for desalination as well as Ni-removal through capacitance deionization (CDI) technology.

Line Impedance Estimation Based Adaptive Droop Control Method for Parallel Inverters

Le, Phuong Minh,Pham, Xuan Hoa Thi,Nguyen, Huy Minh,Hoang, Duc Duy Vo,Nguyen, Tuyen Dinh,Vo, Dieu Ngoc The Korean Institute of Power Electronics 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.

Control Strategy for Accurate Reactive Power Sharing in Islanded Microgrids

Xuan Hoa Thi Pham,Toi Thanh Le 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

This paper presents a control strategy to enhance the accuracy of reactive power sharing between paralleled three-phaseinverters in an islanded microgrid. In this study, the mismatch of power sharing when the line impedances have significantdifferences between inverters connected to a microgrid has been solved, the accuracy of the reactive power sharing in an islandedmicrogrid is increased, the voltage droop slope is tuned to compensate for the mismatch of voltage drops across the lineimpedances by using an enhanced droop controller. The proposed method ensures accurate power sharing even if the microgridhas local loads at the output of the inverters. The control model has been simulated by MATLAB/Simulink with two or threeinverters connected in parallel. Simulation results demonstrate the accuracy of the implemented control method. Furthermore, inorder to validate the theoretical analysis and simulation results, an experimental setup was built in the laboratory. Resultsobtained from the experimental setup verify the effectiveness of the proposed method.

Control Strategy for Accurate Reactive Power Sharing in Islanded Microgrids

Pham, Xuan Hoa Thi,Le, Toi Thanh The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

This paper presents a control strategy to enhance the accuracy of reactive power sharing between paralleled three-phase inverters in an islanded microgrid. In this study, the mismatch of power sharing when the line impedances have significant differences between inverters connected to a microgrid has been solved, the accuracy of the reactive power sharing in an islanded microgrid is increased, the voltage droop slope is tuned to compensate for the mismatch of voltage drops across the line impedances by using an enhanced droop controller. The proposed method ensures accurate power sharing even if the microgrid has local loads at the output of the inverters. The control model has been simulated by MATLAB/Simulink with two or three inverters connected in parallel. Simulation results demonstrate the accuracy of the implemented control method. Furthermore, in order to validate the theoretical analysis and simulation results, an experimental setup was built in the laboratory. Results obtained from the experimental setup verify the effectiveness of the proposed method.

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.

Factors Influencing Innovation Capability and Operational Performance: A Case Study of Power Generation Fields in Vietnam

To Tam NGUYEN,Tuan LE-ANH,Thi Xuan Hoa NGUYEN 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.5

This research examines the effects of organizational learning and network involvement, as well as many contextual factors, on power generation businesses’ innovation capability and operational success in Vietnam. This research also aims to attest to the moderating roles of top management support and company age, and firm possession type in the power generation industry. This study applied the exploratory factor analysis (EFA) and PLS-SEM approach for data analysis. In this research, we have tested hypotheses with data collected from 132 top managers and other key personnel from power generation companies in Vietnam. The results also attest to the moderating role of top management support on the two relationships between organizational learning - innovation capability and network involvement - innovation capability. Another important finding is that the company age has a negative impact on operational performance but shows a positive moderating role in the relationship between innovation capability and operational performance. This study highlights the central roles of organizational learning and innovation capability in impacting the organizational performance of power generation companies. These companies play a key role in supporting the development of industries in practice. This research also emphasizes the moderating roles of top management support and company age and possession type in practice.

New Phenylpropanoid Esters of Sucrose from Polygonum hydropiper and Their Antioxidant Activity

Phan Van Kiem,Nguyen Xuan Nhiem,Nguyen Xuan Cuong,Tran Quynh Hoa,Le Mai Huong,Chua Van Minh,Hoang Thanh Huong,김영호 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.11

By various chromatographic methods, two new phenylpropanoid esters of sucrose named hidropiperosides A (1) and B (2), and three known compounds as vanicosides A (3), B (4), and E (5) were isolated from the methanolic extract of the whole plant of Polygonum hydropiper L. (Polygonaceae). Their structures were elucidated by extensive spectroscopic methods including 1D- and 2D-NMR experiments, as well as ESI-MS analysis. All the isolated compounds were tested for their antioxidant activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay system. Among them, compounds 2 and 3 showed significant antioxidant activity with their SC50 values of 23.4 and 26.7 μg/mL, respectively.

New Phenylpropanoid Esters of Sucrose from Polygonum hydropiper and Their Antioxidant Activity

Kiem, Phan Van,Nhiem, Nguyen Xuan,Cuong, Nguyen Xuan,Hoa, Tran Quynh,Huong, Hoang Thanh,Huong, Le Mai,Minh, Chau Van,Kim, Young-Ho 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.11

By various chromatographic methods, two new phenylpropanoid esters of sucrose named hidropiperosides A (1) and B (2), and three known compounds as vanicosides A (3), B (4), and E (5) were isolated from the methanolic extract of the whole plant of Polygonum hydropiper L. (Polygonaceae). Their structures were elucidated by extensive spectroscopic methods including 1D- and 2D-NMR experiments, as well as ESI-MS analysis. All the isolated compounds were tested for their antioxidant activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay system. Among them, compounds 2 and 3 showed significant antioxidant activity with their $SC_{50}$ values of 23.4 and $26.7{\mu}g/mL$, respectively.