A Laboratory-Scale Study of the Applicability of a Halophilic Sediment Bioelectrochemical System for in situ Reclamation of Water and Sediment in Brackish Aquaculture Ponds: Establishment, Bacterial Community and Performance Evaluation

( Hai The Pham ),( Hien Thi Tran ),( Linh Thuy Vu ),( Hien The Dang ),( Thuy Thu Thi Nguyen ),( Thu Ha Thi Dang ),( Mai Thanh Thi Nguyen ),( Huy Quang Nguyen ),( Byung Hong Kim ) 한국미생물·생명공학회 2019 Journal of microbiology and biotechnology Vol.29 No.7

In this study, we investigated the potential of using sediment bioelectrochemical systems (SBESs) for in situ treatment of the water and sediment in brackish aquaculture ponds polluted with uneaten feed. An SBES integrated into a laboratory-scale tank simulating a brackish aquaculture pond was established. This test tank and the control (not containing the SBES) were fed with shrimp feed in a scheme that mimics a situation where 50% of feed is uneaten. After the SBES was inoculated with microbial sources from actual shrimp pond sediments, electricity generation was well observed from the first experimental week, indicating successful enrichment of electrochemically active bacteria in the test tank sediment. The electricity generation became steady after 3 weeks of operation, with an average current density of 2.3 mA/㎡ anode surface and an average power density of 0.05 mW/㎡ anode surface. The SBES removed 20-30% more COD of the tank water, compared to the control. After 1 year, the SBES also reduced the amount of sediment in the tank by 40% and thus could remove approximately 40% more COD and approximately 52% more nitrogen from the sediment, compared to the control. Insignificant amounts of nitrite and nitrate were detected, suggesting complete removal of nitrogen by the system. PCR-DGGE-based analyses revealed the dominant presence of Methylophilus rhizosphaerae, Desulfatitalea tepidiphila and Thiothrix eikelboomii, which have not been found in bioelectrochemical systems before, in the bacterial community in the sediment of the SBES-containing tank. The results of this research demonstrate the potential application of SBESs in helping to reduce water pollution threats, fish and shrimp disease risks, and thus farmers’ losses.

Electrochemical Detection of TNT by Differential Pulse Adsorptive Stripping Voltammetry at Carbon Paste Electrode Modified by 1-Butyl-3-methylimidazolium Tetrafluoroborate

Ha Thi Thu Vu,Hanh Thi Vinh Le,Yen Thi Hai Pham,Hung Quoc Le,Phong Hong Pham 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.3

Different kinds of materials for electrodes based on glassy carbon, carbon fibers, and modified by an ionic liquid (BMIMBF4) were used to determine 2,4,6-trinitrotoluene (TNT) in water environment by differential pulse adsorptive stripping voltammetry. The modified electrode based on BMIMBF4 showed a better performance than those based on the microelectrode and glassy carbon electrode (GCE) in term of sensitivity. The best performance was obtained with the ionic liquid-modified electrode with 80:10:10 (w/w/w) of the graphite powder/paraffin oil/BMIMBF4 composition in PBS, pH 8. The TNT concentration was linear in the range 1.5 to ~30 ppm for all studied electrodes (r = 0.9978) with a detection limit of 88.6 ppb using IL-CPE (ionic liquid-modified carbon paste electrode). This latter electrode was used to measure real samples taken from Red River, Vietnam. The recovery study for TNT in natural samples gave values from 99.7% to 103.3%. IL-CPE demonstrated long-term stability and reproducibility, with a relative standard deviation of 1.67%.

A Laboratory-Scale Study of the Applicability of a Halophilic Sediment Bioelectrochemical System for in situ Reclamation of Water and Sediment in Brackish Aquaculture Ponds: Effects of Operational Conditions on Performance

( Hai The Pham ),( Phuong Ha Vu ),( Thuy Thu Thi Nguyen ),( Ha Viet Thi Bui ),( Huyen Thanh Thi Tran ),( Hanh My Tran ),( Huy Quang Nguyen ),( Byung Hong Kim ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.10

Sediment bioelectrochemical systems (SBESs) can be integrated into brackish aquaculture ponds for in-situ bioremediation of the pond water and sediment. Such an in-situ system offers advantages including reduced treatment cost, reusability and simple handling. In order to realize such an application potential of the SBES, in this laboratory-scale study we investigated the effect of several controllable and uncontrollable operational factors on the in-situ bioremediation performance of a tank model of a brackish aquaculture pond, into which a SBES was integrated, in comparison with a natural degradation control model. The performance was evaluated in terms of electricity generation by the SBES, Chemical oxygen demand (COD) removal and nitrogen removal of both the tank water and the tank sediment. Real-life conditions of the operational parameters were also experimented to understand the most close-to-practice responses of the system to their changes. Predictable effects of controllable parameters including external resistance and electrode spacing, similar to those reported previously for the BESs, were shown by the results but exceptions were observed. Accordingly, while increasing the electrode spacing reduced the current densities but generally improved COD and nitrogen removal, increasing the external resistance could result in decreased COD removal but also increased nitrogen removal and decreased current densities. However, maximum electricity generation and COD removal efficiency difference of the SBES (versus the control) could be reached with an external resistance of 100 Ω, not with the lowest one of 10 Ω. The effects of uncontrollable parameters such as ambient temperature, salinity and pH of the pond (tank) water were rather unpredictable. Temperatures higher than 35℃ seemed to have more accelaration effect on natural degradation than on bioelectrochemical processes. Changing salinity seriously changed the electricity generation but did not clearly affect the bioremediation performance of the SBES, although at 2.5% salinity the SBES displayed a significantly more efficient removal of nitrogen in the water, compared to the control. Variation of pH to practically extreme levels (5.5 and 8.8) led to increased electricity generations but poorer performances of the SBES (vs. the control) in removing COD and nitrogen. Altogether, the results suggest some distinct responses of the SBES under brackish conditions and imply that COD removal and nitrogen removal in the system are not completely linked to bioelectrochemical processes but electrochemically enriched bacteria can still perform nonbioelectrochemical COD and nitrogen removals more efficiently than natural ones. The results confirm the application potential of the SBES in brackish aquaculture bioremediation and help propose efficient practices to warrant the success of such application in real-life scenarios.

Impact of Vocational Training on Wages of Ethnic Minority Labors in Vietnam

DO, Ha Thi Hai,MAI, Cuong Ngoc,MAI, Anh Ngoc,NGUYEN, Nui Dang,PHAM, Toan Ngoc,LE, Huong Thi Thu,TRAN, Manh Dung,VU, Tri Tuan Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.6

This research investigates the impact of vocational training on wages of ethnic minority labors in emerging countries; Vietnam is the case study. The study uses secondary data from 2014 to 2018 collected through Vietnam Household Living Standards Surveys (VHLSS) conducted by the General Statistics Office. In order to analyze the impact of vocational training on wages of ethnic minority areas in Vietnam, this research creates ethnic area variables. According to Vietnamese regulations, ethnic areas are communes of 51 different provinces, inhabited by ethnic minority people. The statistics from VHLSS in 2018, show that the proportion of labors of working age with a certificate was 22.5%. The research employs Heckman Sample Selection Model to estimate the impact of vocation training on wage of labors in ethnic minority areas. The results show that vocational training plays a crucial role in improving the wages of ethnic minorities and has a positive impact. However, apart from the achieved outcomes, vocational training and job creation for ethnic minorities are not without limitations and shortcomings. Based on the findings, some recommendations to ethnic minority labors, enterprises and the Government are proposed to encourage participation in vocational training for the purpose of promoting the efficiency of the labor market.

Colorimetric Determination of Singlet Oxygen Scavengers Using a Protein Photosensitizer

Miso Kim,Eun Hye Kim,Thi Hai Yen Pham,Tuan Anh Hoang Le,Thi Phuong Do,Thi Nga Nguyen,Thi Cuc Nguyen,Ha Phuong Trieu,Thi Thao Do,김영필 한국바이오칩학회 2020 BioChip Journal Vol.14 No.2

Despite the diverse roles of singlet oxygen ( 1 O2) in plants and animals, simple detection of 1 O2 has been limited due to technical difficulties. Here we report a colorimetric method for visualizing the generation and suppression of 1 O2 using a protein photosensitizer, mini singlet oxygen generator (miniSOG). Upon external light irradiation, miniSOG strongly produced 1 O2 and oxidized a universal chromogenic reagent, tetramethylbenzidine, leading to a rapid color change in solution. We used this finding to demonstrate the 1 O2 scavenging effects of well-known antioxidants and of natural compounds extracted from plants. Owing to its high usability and simplicity, our developed assay platform will be useful for screening potential scavengers for reactive oxygen species and will promote the development of various antioxidants.

Asbestos and Asbestos-related Diseases in Vietnam: In reference to the International Labor Organization/World Health Organization National Asbestos Profile

Pham, Van Hai,Tran, Thi Ngoc Lan,Le, Giang Vinh,Movahed, Mehrnoosh,Jiang, Ying,Pham, Nguyen Ha,Ogawa, Hisashi,Takahashi, Ken Occupational Safety and Health Research Institute 2013 Safety and health at work Vol.4 No.2

This paper describes progress on formulating a national asbestos profile for the country of Vietnam. The Center of Asbestos Resource, Vietnam, formulated a National Profile on Asbestos-related Occupational Health, with due reference to the International Labor Organization/World Health Organization National Asbestos Profile. The Center of Asbestos Resource was established by the Vietnamese Health Environment Management Agency and the National Institute of Labor Protection, with the support of the Australian Agency for International Development, as a coordinating point for asbestos-related issues in Vietnam. Under the National Profile on Asbestos-related Occupational Health framework, the Center of Asbestos Resource succeeded in compiling relevant information for 15 of the 18 designated items outlined in the International Labor Organization/World Health Organization National Asbestos Profile, some overlaps of the information items notwithstanding. Today, Vietnam continues to import and use an average of more than 60,000 metric tons of raw asbestos per year. Information on asbestos-related diseases is limited, but the country has begun to diagnose mesothelioma cases, with the technical cooperation of Japan. As it stands, the National Profile on Asbestos-related Occupational Health needs further work and updating. However, we envisage that the National Profile on Asbestos-related Occupational Health will ultimately facilitate the smooth transition to an asbestos-free Vietnam.

Effect of post-synthesis annealing on properties of SnS nanospheres and its solar cell performance

트롱윈탐윈,Ha Hai Thi Hoang,Thanh Kieu Trinh,Viet Thanh Hau Pham,Ryan Patrick Smith,박진호 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.4

SnS nanospheres (NSPs) were synthesized, and the effects of thermal annealing on the structural, morphological, chemical compositional and optical properties were examined. As-synthesized SnS NPSs with a mean size of 3- 4 nm underwent a solid state morphological transformation by high temperature annealing in a nitrogen environment. Upon annealing, the size of SnS NSP increased to 5-6 nm with enhanced crystallinity. Also, the photoluminescence (PL) of the nitrogen-annealed samples slightly decreased in intensity with accompanying red-shift in spectrum. The power conversion efficiency of the solar cells using a polymer and the SnS NSPs was ~0.71%. These results confirm that the SnS NSPs demonstrate a potential as an inorganic material to be used in organic-inorganic hybrid bulk heterojunction (BHJ) photovoltaic devices.

Asbestos and Asbestos-related Diseases in Vietnam: In reference to the International Labor Organization/World Health Organization National Asbestos Profile

Van Hai Pham,Thi Ngoc Lan Tran,Giang Vinh Le,Mehrnoosh Movahed,Ying Jiang,Nguyen Ha Pham,Hisashi Ogawa,Ken Takahashi 한국산업안전보건공단 산업안전보건연구원 2013 Safety and health at work Vol.4 No.2

This paper describes progress on formulating a national asbestos profile for the country of Vietnam. The Center of Asbestos Resource, Vietnam, formulated a National Profile on Asbestos-related Occupational Health, with due reference to the International Labor Organization/World Health Organization National Asbestos Profile. The Center of Asbestos Resource was established by the Vietnamese Health Environment Management Agency and the National Institute of Labor Protection, with the support of the Australian Agency for International Development, as a coordinating point for asbestos-related issues in Vietnam. Under the National Profile on Asbestos-related Occupational Health framework, the Center of Asbestos Resource succeeded in compiling relevant information for 15 of the 18 designated items outlined in the International Labor Organization/World Health Organization National Asbestos Profile, some overlaps of the information items notwithstanding. Today, Vietnam continues to import and use an average of more than 60,000 metric tons of raw asbestos per year. Information on asbestos-related diseases is limited, but the country has begun to diagnose mesothelioma cases, with the technical cooperation of Japan. As it stands, the National Profile on Asbestos-related Occupational Health needs further work and updating. However, we envisage that the National Profile on Asbestos-related Occupational Health will ultimately facilitate the smooth transition to an asbestos-free Vietnam.

The Effect of the Ratio of C45 Carbon to Graphene on the Si/C Composite Materials Used as Anode for Lithium-ion Batteries

Hoang Anh Nguyen,Thi Nam Pham,Le Thanh Nguyen Huynh,Tran Ha Trang Nguyen,Viet Hai Le,Nguyen Thai Hoang,Thi Thom Nguyen,Thi Thu Trang Nguyen,Dai Lam Tran,Thi Mai Thanh Dinh The Korean Electrochemical Society 2024 Journal of electrochemical science and technology Vol.15 No.2

Due to its high theoretical capacity, Silicon (Si) has shown great potential as an anode material for lithium-ion batteries (LIBs). However, the large volume change of Si during cycling leads to poor cycling stability and low Coulombic efficiency. In this study, we synthesized Si/Carbon C45:Graphene composites using a ball-milling method with a fixed Si content (20%) and investigated the influence of the C45/Gr ratio on the electrochemical performance of the composites. The results showed that carbon C45 networks can provide good conductivity, but tend to break at Si locations, resulting in poor conductivity. However, the addition of graphene helps to reconnect the broken C45 networks, improving the conductivity of the composite. Moreover, the C45 can also act as a protective coating around Si particles, reducing the volume expansion of Si during charging/discharging cycles. The Si/C45:Gr (70:10 wt%) composite exhibits improved electrochemical performance with high capacity (~1660 mAh g^-1 at 0.1 C) and cycling stability (~1370 mAh g^-1 after 100 cycles). This work highlights the effective role of carbon C45 and graphene in Si/C composites for enhancing the performance of Si-based anode materials for LIBs.

Consumer Behavior and Purchasing Intention Toward Country of Origin Labeling Products: An Empirical Study in Vietnam

Luc Manh HIEN,Nguyen Thi Anh TRAM,Le Thi Hai HA,Pham Thi Thuy VAN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.8

The role of the garment and textile industry is particularly important in the economies of many countries in the context of international goods trade. There is no denying that the garment and textile industry contributes significantly to the economic growth in the global economy. The study seeks to investigate the relationship between control variables and Vietnamese consumers’ intention to buy Chinese garment products. While previous research has found some control variables influencing consumers’ intention to buy products, little research has been done about the influence of control variables on consumers’ intention to buy Chinese garment products, in developing countries like Vietnam. In particular, the textile industry plays an important role in export, but outsourcing is accounting for a high proportion of trade, hence, it is necessary to increase innovation to increase consumers’ intention to buy domestic garment products. The data is collected from a survey of 406 Vietnamese consumers’ in Hanoi city and Ho Chi Minh City. The methodology includes a mixed-method, i.e. qualitative method and quantitative method. The quantitative method applies SPSS analysis to measure the control variables’ influence on Vietnamese consumers’ intention to buy Chinese garment products. The results identify 1 control variable that impacts Vietnamese consumers’ intention to buy Chinese garment products, which is domicile.