Doi Moi Policy and Socio-Economic Development in Vietnam, 1986-2005

( Nhuan Kien Tran ),( Heo Yoon ) 한국외국어대학교 외국학종합연구센터 2008 International Area Studies Review Vol.11 No.1

Preliminary reports on the effect of elevated air temperature on rice growth

Nhuan Duc Nguyen,Kyu Jong Lee,Doug-Hwan Choi,Byun-Woo Lee 한국작물학회 2008 한국작물학회 학술발표대회 논문집 Vol.2008 No.10

Korea has experienced a rapid warming of 1.5℃ during the last 100 years and it is projected more faster rise of air temperature in the future. Temperature is an important factor that impacts directly on the growth and development of plants. To figure out the impact of temperature rising on rice growth, grain yield, and quality, an experiment was conducted at the 3 plastic houses that were controlled to ambient, ambient+1.5℃, and ambient+3℃throughout the growing season at the Seoul National University Experimental Farm. A rice variety "Hwaseongbyeo“ was grown using 1/5000a Wagner pot under two nitrogen levels of 12 and 18kg/10a. Heading date in elevated temperature treatments was earlier by two days than in ambient temperature. Compared to the ambient temperature, number of tiller, leaf area index, and dry weight of root, stem, leaf, and panicle was greater in elevated temperature conditions throughout the rice growing season, the difference being smaller in later grain filling period. There was no interaction effect on growth between nitrogen levels and temperature treatments. Grain yield and grain quality are under measurements.

Effects of Drying Methods on Contents of Bioactive Compounds and Antioxidant Activities of Black Chokeberries (Aronia melanocarpa)

Nhuan Do Thi,황은선 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.1

Optimal drying techniques for maintaining high levels of bioactive compounds and antioxidant activities in black chokeberries were investigated. Effects of 3 drying methods on total bioactive compound contents and in vitro antioxidant activities in 80% ethanol extracts were evaluated. Fresh black chokeberries were dried using sun-drying, freeze-drying, and oven-drying. Highest amounts of total polyphenols, flavonoids, and anthocyanins were detected in freeze-dried black chokeberry extracts after sun and oven-drying. 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis-3- ethylbenzothiazoline-6-sulphonic acid (ABTS), and superoxide anion scavenging activities in black chokeberry extracts were also evaluated. Freeze-dried berries produced strongest antioxidant activities. Freeze-drying was the optimal drying method for maintaining high levels of bioactive compounds in 80% ethanol extracts of dried black chokeberries.

Bioactive Compound Contents and Antioxidant Activity in Aronia (Aronia melanocarpa ) Leaves Collected at Different Growth Stages

Nhuan Do Thi,Eun-Sun Hwang 한국식품영양과학회 2014 Preventive Nutrition and Food Science Vol.19 No.3

The bioactive compounds and antioxidant activity of aronia leaves at different stages of maturity were identified and evaluated. Young and old leaves were approximately 2 months of age and 4 months of age, respectively. The young leaves contained more polyphenols and flavonoids than the old leaves. Three phenolic compounds (i.e., chlorogenic acid, p-coumaric acid, and rutin) were detected by HPLC. Antioxidant activity was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, 2,2´-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical, and superoxide anion radical scavenging assays. The reducing power of aronia leaf extracts increased in a concentration-dependent manner (0∼100 μg/mL). The antioxidant activity of the 80% ethanol extract was greater than that of distilled water extract. The high phenolic compound content indicated that these compounds contribute to antioxidant activity. The overall results indicate that aronia leaves contain bioactive compounds, and that younger aronia leaves may be more favorable for extracting antioxidative ingredients because they contain more polyphenols.

Effects of Different Cooking Methods on Bioactive Compound Content and Antioxidant Activity of Water Spinach (Ipomoea aquatica)

Nhuan Do Thi,황은선 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.3

Water spinach (Ipomoea aquatica) is a green leafy vegetable commonly found in Vietnam and other tropical countries. We identified the best extraction solvent and compared the effects of different cooking methods on phytochemical contents and antioxidant activity of water spinach. Steamed water spinach extracted with 80% ethanol had the highest amounts of 35.0 mg/g total chlorophylls, 7.1 mg/g carotenoids, 35.6 mg/g total polyphenols, and 40.4 mg/g total flavonoids. The steaming process showed higher antioxidant activity than the uncooking or boiling process. The 80% ethanol extract showed a higher level of antioxidant activities than the water extract. The antioxidant activity was measured with the DPPH, ABTS, hydroxyl and superoxide anion racial scavenging assays as well as the reducing power activity assay were increased in a concentration dependent manner. The overall results support that water spinach contains bioactive compounds and they may play a positive role in our health.

Time-sequential fibroblast-to-myofibroblast transition in elastin-variable 3D hydrogel environments mediated by calcium signaling

Nhuan T. Do,이선영,이윤서,신채호,김대호,이태걸,손진경,김세화 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Background Fibrosis plays an important role in both normal physiological and pathological phenomena as fibroblasts differentiate to myofibroblasts. The activation of fibroblasts is determined through interactions with the surrounding extracellular matrix (ECM). However, how this fibroblast-to-myofibroblast transition (FMT) is regulated and affected by elastin concentration in a three-dimensional (3D) microenvironment has not been investigated. Methods We developed an insoluble elastin-gradient 3D hydrogel system for long-lasting cell culture and studied the molecular mechanisms of the FMT in embedded cells by nanoflow LC–MS/MS analysis along with validation through real-time PCR and immunofluorescence staining. Results By optimizing pH and temperature, four 3D hydrogels containing fibroblasts were successfully fabricated having elastin concentrations of 0, 20, 50, and 80% in collagen. At the low elastin level (20%), fibroblast proliferation was significantly increased compared to others, and in particular, the FMT was clearly observed in this condition. Moreover, through mass spectrometry of the hydrogel environment, it was confirmed that differentiation proceeded in two stages. In the early stage, calcium-dependent proteins including calmodulin and S100A4 were highly associated. On the other hand, in the late stage after several passages of cells, distinct markers of myofibroblasts were presented such as morphological changes, increased production of ECM, and increased α-SMA expression. We also demonstrated that the low level of elastin concentration induced some cancer-associated fibroblast (CAF) markers, including PDGFR-β, and fibrosis-related disease markers, including THY-1. Conclusion Using our developed 3D elastin-gradient hydrogel system, we evaluated the effect of different elastin concentrations on the FMT. The FMT was induced even at a low concentration of elastin with increasing CAF level via calcium signaling. With this system, we were able to analyze varying protein expressions in the overall FMT process over several cellular passages. Our results suggest that the elastin-gradient system employing nonlinear optics imaging provides a good platform to study activated fibroblasts interacting with the microenvironment, where the ECM plays a pivotal role.

Bioactive Compound Contents and Antioxidant Activity in Aronia (Aronia melanocarpa ) Leaves Collected at Different Growth Stages

Thi, Nhuan Do,Hwang, Eun-Sun The Korean Society of Food Science and Nutrition 2014 Preventive Nutrition and Food Science Vol.19 No.3

The bioactive compounds and antioxidant activity of aronia leaves at different stages of maturity were identified and evaluated. Young and old leaves were approximately 2 months of age and 4 months of age, respectively. The young leaves contained more polyphenols and flavonoids than the old leaves. Three phenolic compounds (i.e., chlorogenic acid, p-coumaric acid, and rutin) were detected by HPLC. Antioxidant activity was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical, and superoxide anion radical scavenging assays. The reducing power of aronia leaf extracts increased in a concentration-dependent manner ($0{\sim}100{\mu}g/mL$). The antioxidant activity of the 80% ethanol extract was greater than that of distilled water extract. The high phenolic compound content indicated that these compounds contribute to antioxidant activity. The overall results indicate that aronia leaves contain bioactive compounds, and that younger aronia leaves may be more favorable for extracting antioxidative ingredients because they contain more polyphenols.

Effect of Air Temperature Rise on Growth and Yield of Rice

Duc-Nhuan Nguyen,Kyu-Jong Lee,Doug-Hwan Choi,Byun-Woo Lee 한국작물학회 2010 한국작물학회 학술발표대회 논문집 Vol.2010 No.04

Korea has experienced a rapid warming of 1.5℃during the last 100 years and even faster rise of air temperature is being projected in the future. This experiment was done to figure out the impact of the predidted temperature rise on the growth and yield of rice. Two rice varieties, "Hwaseongbyeo" and "Dasanbyeo" were grown in 1/5000a Wagner pot under the four plastic houses that were controlled to ambient, ambient+1.5℃, ambient+3℃ and ambient+5℃ throughout the rice growing season. Heading dates in the elevated temperature treatments were three to five days earlier than in the ambient temperature treatment. Rice growth was affected by temperature treatments differentially according to the tested cultivars. Hwaseongbyeo(japonica) showed significant reduction of shoot dry weight under ambient+5.0℃ treatment compared to the other treatments, while Dasanbyeo(tongil-type) showed significant increase of shoot and root dry weight under the elevated temperature treatments. The number of panicles per pot and spikelets per panicle and per pot was not significantly different among temperature treatments in both cultivars tested, but significantly lower grain yield was observed under the treatments raising the air temperature to the level of 3.0℃ and 5.0℃ above the ambient air temperature. This lower grain yield in the elevated temperature treatment of ambient+3℃ was attributed mainly to the decrease of grain weight due to the shortening of grain filling period, while the drastic yield reduction in the treatment of ambient+5℃ was caused not only by the lower grain weight but also by the marked increase in spikelet sterility due to the high temperature at meiotic and flowering stage. In conclusion, the ongoing global warming is expected to decrease the grain yield not only by decreasing the grain filling period in the near future but also increasing the spikelet sterility under the long-term projected climate of Korea.

Technology, Factor Proportion and Complementarity

Tran Nhuan Kien,Yoon Heo 인하대학교 정석물류통상연구원 2014 JOURNAL OF INTERNATIONAL LOGISTICS AND TRADE Vol.12 No.1

This paper aims at examining the dynamic patterns and traits of bilateral trade between Korea and Vietnam. The major findings of this paper can be summarized as follows. First, the structure of trade between Korea and Vietnam conforms to each country’s factor proportion. Second, the structure of Korea’s imports from Vietnam did not change over the last two decades. In other words, Vietnam has failed to climb up the industrial ladder. Third, the degree of intra-industry trade between Korea and Vietnam has been low and unstable. Fourth, the trade pattern between Korea and Vietnam has been complementary not competitive in nature. Korea-Vietnam FTA will open a new horizon for the deeper vertical integration of the two.

Dynamic Patterns of Korea-Vietnam Trade Relations

Tran Nhuan Kien,이홍렬,허윤 한국외국어대학교 국제지역연구센터 2010 International Area Studies Review Vol.13 No.2

This paper analyzes the dynamic patterns and trends pertaining to bilateral trade between Korea and Vietnam over the past decade. The principal findings of this paper are as follows. First, the commodity trade patterns between Korea and Vietnam have remained virtually unchanged, even though the volume of bilateral trade between the two has expanded significantly over the past decade. Second, Korean exports have been characterized by a high and growing share of intermediate goods, and Korean imports by a high and growing share of consumption goods. Third, the technological level of Korea’s exports to Vietnam is much higher than that of Vietnam’s exports to Korea. Fourth, Vietnam’s exports are less diverse than Korea’s. Fifth, bilateral trade between Korea and Vietnam has been less intense than these countries’ trade with other countries in recent years. Sixth, Korea-Vietnam bilateral trade has principally been inter-industry trade. Seventh, Vietnam enjoys a comparative advantage largely in either primary products or low–technology manufactures, whereas Korea enjoys a comparative advantage primarily in manufactured products and machinery and transport equipment. Finally, the high degree of trade complementarity between Korea and Vietnam makes it plausible that a freer trade agreement may bring about greater benefit for both countries.