• 제목/요약/키워드: Vietnam National University

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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

  • Pham, Hai The;Vu, Phuong Ha;Nguyen, Thuy Thu Thi;Bui, Ha Viet Thi;Tran, Huyen Thanh Thi;Tran, Hanh My;Nguyen, Huy Quang;Kim, Byung Hong
    • Journal of Microbiology and Biotechnology
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    • v.29 no.10
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    • pp.1607-1623
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    • 2019
  • 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 $100{\Omega}$, not with the lowest one of $10{\Omega}$. The effects of uncontrollable parameters such as ambient temperature, salinity and pH of the pond (tank) water were rather unpredictable. Temperatures higher than $35^{\circ}C$ 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 non-bioelectrochemical 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.

Molecular analysis of chicken interferon-alpha inducible protein 6 gene and transcriptional regulation

  • Jeong-Woong Park;Marc Ndimukaga;Jaerung So;Sujung Kim;Anh Duc Truong;Ha Thi Thanh Tran;Hoang Vu Dang;Ki-Duk Song
    • Journal of Animal Science and Technology
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    • v.65 no.1
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    • pp.183-196
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    • 2023
  • Interferon-alpha inducible protein 6 (IFI6) is an interferon-stimulated gene (ISG), belonging to the FAM14 family of proteins and is localized in the mitochondrial membrane, where it plays a role in apoptosis. Transcriptional regulation of this gene is poorly understood in the context of inflammation by intracellular nucleic acid-sensing receptors and pathological conditions caused by viral infection. In this study, chicken IFI6 (chIFI6) was identified and studied for its molecular features and transcriptional regulation in chicken cells and tissues, i.e., lungs, spleens, and tracheas from highly pathogenic avian influenza virus (HPAIV)-infected chickens. The chIFI6-coding sequences contained 1638 nucleotides encoding 107 amino acids in three exons, whereas the duck IFI6-coding sequences contained 495 nucleotides encoding 107 amino acids. IFI6 proteins from chickens, ducks, and quail contain an IF6/IF27-like superfamily domain. Expression of chIFI6 was higher in HPAIV-infected White Leghorn chicken lungs, spleens, and tracheas than in mock-infected controls. TLR3 signals regulate the transcription of chIFI6 in chicken DF-1 cells via the NF-κB and JNK signaling pathways, indicating that multiple signaling pathways differentially contribute to the transcription of chIFI6. Further research is needed to unravel the molecular mechanisms underlying IFI6 transcription, as well as the involvement of chIFI6 in the pathogenesis of HPAIV in chickens.

HOME SWEET HOME IN VÕ PHIẾN'S TUỲ BÚT

  • Vy, Tran Tinh
    • SUVANNABHUMI
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    • v.14 no.2
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    • pp.207-231
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    • 2022
  • From being understood as a dwelling, the concept of home is extended to denote belongingness and a sense of attachment in which spiritual, ethnic, religious and historical identities shape a sense of self. Hence, home with its expanded definitions is considered as a cross-cutting and fundamental theme in works by Võ Phiến, one of the diaspora's towering minds who devoted his life to capturing the rich details of Vietnamese culture, its villages and locals. This article pays attention to the cultural space created through Võ Phiến's tuỳ bút written when he lived in Saigon and California. Many representations of home were argued as evidence of subtle influences of the historical and social context on the way Võ Phiến perceived and built his own homeland. By observing disruption and continuity through the expressions of the home in Võ Phiến's writing, we shed light on how Võ Phiến managed to create an indigenous cultural space towards social interactions of Western ideology in South Vietnam from 1964 to 1975.

Determinants of Share Prices of Listed Companies Operating in the Steel Industry: An Empirical Case from Vietnam

  • NGUYEN, Phu Ha;NGUYEN, Phi-Hung;TSAI, Jung-Fa;NGUYEN, Thanh Tam;HO, Van Nguyen;DAO, Trong-Khoi
    • The Journal of Asian Finance, Economics and Business
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    • v.7 no.12
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    • pp.131-138
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    • 2020
  • In accordance with huge demand for capital to meet the expansion of steel production, there are more and more steel companies who have officially listed their stocks in HOSE and HNX. One of the key issues in successful initial public offerings and seasonal offerings for these companies is how to make stocks of steel companies become more attractive in the eyes of investors. The purpose of this research is to analyze the determinants of share prices of listed steel companies in Vietnam. This study utilized macro-economic variables, ratios and indicators representing characteristics of steel industry collected from Quarter 1/2006 to Quarter 4/2019 in association with the panel data and the feasible generalized least square (FGLS) model to evaluate the degree of these factors on the share prices. The results of the research show that ROE, Cons_rate, and CO2_rate are three main factors affecting the share prices of listed steel companies. Among which, ROE and Cons_rate have a positive effect, while CO2_rate has a negative effect on the share prices of listed steel companies. It also confirms the relationship between the environmental factor, construction industry factor and the stock prices. This lays foundations for recommendations for the future policies towards environmental protection and sustainable development.

A Fuzzy AHP Model for Selection of Consultant Contractor in Bidding Phase in Vietnam

  • Ha, Tran Thanh;Hoai, Long Le;Lee, Young Dai
    • Journal of Construction Engineering and Project Management
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    • v.5 no.2
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    • pp.35-43
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    • 2015
  • Project Management Consultant (PMC) plays a vital role in the overall performance of any project. Selecting right PMC for right project is the most crucial challenge for any construction owner. Thus, PMC selection is one of the main decisions made by owners at the early phase of construction project. It is not easy for the project owner to select a competent PMC due to the fuzziness, imprecision, vagueness, incomplete and qualitative criteria of the decision. This paper presents a model for selecting PMC contractor using the Fuzzy Analytical Hierarchy Process (FAHP). And a fuzzy number based framework is proposed to be a viable method for PMC contractor selection. A case study to illustrate the application of the model is also presented in this paper.

Quasinormal Subgroups in Division Rings Radical over Proper Division Subrings

  • Le Qui Danh;Trinh Thanh Deo
    • Kyungpook Mathematical Journal
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    • v.63 no.2
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    • pp.187-198
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    • 2023
  • The motivation for this study comes from a question posed by I.N. Herstein in the Israel Journal of Mathematics in 1978. Specifically, let D be a division ring with center F. The aim of this paper is to demonstrate that every quasinormal subgroup of the multiplicative group of D, which is radical over some proper division subring, is central if one of the following conditions holds: (i) D is weakly locally finite; (ii) F is uncountable; or (iii) D is the Mal'cev-Neumann division ring.

Relationship between Accrual Anomaly and Stock Return: The Case of Vietnam

  • DANG, Hung Ngoc;TRAN, Dung Manh
    • The Journal of Asian Finance, Economics and Business
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    • v.6 no.4
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    • pp.19-26
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    • 2019
  • The study investigates the impact of accrual anomaly on stock return ratio of listed firms in Vietnam. Data were collected from listed firms for the period from 2008 to 2018. To learn about the causes of accrual anomaly in returns and future rate of returns on the Vietnamese stock market, this research is based on accrual analysis of Richardson, Sloan, Soliman, and Tuna (2006) on growth and effective components. We employ GLS regression model for examining the impact of accrual anomaly on stock return ratio and T-test for checking the difference between the lowest and the highest portfolio. The results show that accounting distortion is the main factor impacting the stock return, not growth determinant. Both two determinants of accounting distortion and growth contribute the explanation of the impact of accrual anomaly on profit and future stock return ratio. Experimental evidence confirms an abnormal existence of accrual in the Vietnam stock market. Aggregate accrual is negatively correlated with future operating profit and future stock return. However, after considering the factors contributing to the impact of future profitability and return on stock returns, the study results show that accounting distortion can account for low sustainability of income that is not growth.

Financial Development, Income Inequality and the Role of Democracy: Evidence from Vietnam

  • NGUYEN, Hung Thanh
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.11
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    • pp.21-29
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    • 2021
  • The objective of this study is to see how a country's level of democracy impacts the relationship between financial development and income disparity. We argue that political regimes, supported by their degree of democracy, are important for various decentralization theories to predict the impact of financial development on income inequality. Our study tests this argument using Vietnam time series data for the period 2000-2020 through the ARDL model. The financial development variable is represented by five proxies, the income inequality variable is represented by the GINI coefficient and the role of democracy is represented by the Freedom House Index. Data serving for the study is taken from data sources with high reliability. The results of the study have strong evidence that (1) financial development has a positive impact on income inequality, (2) democratic government will reduce national income inequality. (3) And a higher degree of democracy tends to mitigate the positive impact of financial development on income inequality. Thus, our study contributes to the literature by providing a new look at the mixed results regarding the relationship between financial development and theoretical income inequality. Finally, the article provides policy implications for the Government of Vietnam.

The Impact of Capital Structure on Firm's Profitability: A Case Study of the Rubber Industry in Vietnam

  • CO, Huong Thi Thanh;UONG, Trang Thi Mai;NGUYEN, Cong Van
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.7
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    • pp.469-476
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    • 2021
  • This study aims to examine and measure the impact of capital structure on the profitability of companies in emerging markets. The research sample includes eighteen rubber companies listed on the Vietnam stock exchange from 2015-2019. After collecting the research data, it was imported into excel to calculate the criteria for the research model. By using Stata 16 software, the study selected a data processing model and evaluated the relevance of the regression analysis model. The research results show that the profitability of listed rubber companies in Vietnam (measured by return on equity (ROE) has a positive relationship with the debt-to-asset ratio but has a negative relationship with the long-term debt-to-asset ratio. The results also show a positive impact of firm size and revenue growth on profitability while liquidity and the ratio of tangible fixed assets to total assets do not affect significantly. These results are consistent with most of the previously published studies. However, in contrast to many previous studies, our study shows that the long-term debt-to-assets ratio has a negative effect on profitability while the debt-to-asset ratio has a positive effect. This is entirely consistent with the characteristics of long-term debt use in emerging markets.