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A New Dimeric Lignan from the Stems of Willughbeia edulis
Nguyen, Hai Xuan,Do, Truong Nhat Van,Le, Tho Huu,Dang, Phu Hoang,Nguyen, Mai Thanh Thi,Nguyen, Nhan Trung The Korean Society of Pharmacognosy 2022 Natural Product Sciences Vol.28 No.2
As part of our continued study on the chemical constituents of Willughbeia edulis stems, a new dimeric lignan named edulignan (1) was isolated from its EtOAc-soluble extract. Based on NMR spectroscopic interpretation, the planar structure of 1 has been suggested to have two 2-substituted 4-chromanone subunits with different stereochemical configurations. In addition, the MS/MS analysis of the products obtained by acid-catalyzed hydrolysis of 1 was supportive of its structure. Unfornatually, the new compound 1 did not show 𝛼-glucosidase inhibitory activity with an IC<sub>50</sub> value > 250 𝜇M.
Treatment of ramie leaf β-amylase for preliminary purification
Dang, Nguyen Dang Hai,Lee, Jin-Sil Korean Society of Food Science and Technology 2016 한국식품과학회지 Vol.48 No.6
The thermal properties of ramie leaf ${\beta}$-amylase (RBA) were examined to develop a novel process for enzyme purification. The thermostability of RBA extract prepared from ramie leaf powder was examined at various temperatures. RBA activity decreased slightly, whereas other carbohydrate-active enzymes, such as $\small{D}$-enzyme, were rapidly inactivated during 30 min incubation at $60^{\circ}C$. When the heat-treated extract was incubated with various substrates, maltose was produced exclusively as the major product, whereas the untreated crude extract produced maltose and other maltooligosaccharides. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, fewer protein bands were observed for the heat-treated extract than the untreated extract, indicating that the thermostable RBA was partially purified and other thermolabile enzymes were eliminated. Thus, the treatment of the RBA extract at $60^{\circ}C$ for 30 min resulted in 5.4-fold purification with a recovery yield of 90%.
Nguyen, Dang Hai Dang,Park, Jong-Tae,Shim, Jae-Hoon,Tran, Phuong Lan,Oktavina, Ershita Fitria,Nguyen, Thi Lan Huong,Lee, Sung-Jae,Park, Cheon-Seok,Li, Dan,Park, Sung-Hoon,Stapleton, David,Lee, Jin-Sil American Society for Microbiology 2014 Journal of Bacteriology Vol.196 No.11
<P>We studied the activity of a debranching enzyme (TreX) from <I>Sulfolobus solfataricus</I> on glycogen-mimic substrates, branched maltotetraosyl-β-cyclodextrin (Glc<SUB>4</SUB>-β-CD), and natural glycogen to better understand substrate transglycosylation and the effect thereof on glycogen debranching in microorganisms. The validation test of Glc<SUB>4</SUB>-β-CD as a glycogen mimic substrate showed that it followed the breakdown process of the well-known yeast and rat liver extract. TreX catalyzed both hydrolysis of α-1,6-glycosidic linkages and transglycosylation at relatively high (>0.5 mM) substrate concentrations. TreX transferred maltotetraosyl moieties from the donor substrate to acceptor molecules, resulting in the formation of two positional isomers of dimaltotetraosyl-α-1,6-β-cyclodextrin [(Glc<SUB>4</SUB>)<SUB>2</SUB>-β-CD]; these were 6<SUP>1</SUP>,6<SUP>3</SUP>- and 6<SUP>1</SUP>,6<SUP>4</SUP>-dimaltotetraosyl-α-1,6-β-CD. Use of a modified Michaelis-Menten equation to study substrate transglycosylation revealed that the <I>k</I><SUB>cat</SUB> and <I>K<SUB>m</SUB></I> values for transglycosylation were 1.78 × 10<SUP>3</SUP> s<SUP>−1</SUP> and 3.30 mM, respectively, whereas the values for hydrolysis were 2.57 × 10<SUP>3</SUP> s<SUP>−1</SUP> and 0.206 mM, respectively. Also, enzyme catalytic efficiency (the <I>k</I><SUB>cat</SUB>/<I>K<SUB>m</SUB></I> ratio) increased as the degree of polymerization of branch chains rose. In the model reaction system of <I>Escherichia coli</I>, glucose-1-phosphate production from glycogen by the glycogen phosphorylase was elevated ∼1.45-fold in the presence of TreX compared to that produced in the absence of TreX. The results suggest that outward shifting of glycogen branch chains via transglycosylation increases the number of exposed chains susceptible to phosphorylase action. We developed a model of the glycogen breakdown process featuring both hydrolysis and transglycosylation catalyzed by the debranching enzyme.</P>
Magnetocaloric Effect in Fe-Ni-Zr Alloys Prepared by Using the Rapidly-quenched Method
Nguyen Huy Dan,Nguyen Huu Duc,Tran Dang Thanh,Nguyen Hai Yen,Ngac An Bang,Do Thi Kim Anh,판더롱,유성초 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
Fe90−xNixZr10 (x = 0, 5, 10, 15, 20 and 25) ribbons with various thicknesses were prepared byusing a melt-spinning technique. The Curie temperature, TC, of the alloys dramatically decreasedfrom 960 K to room temperature at high quenching rates. When the alloys had an amorphousstructure, their TC strongly depended on the Ni concentration. The maximum entropy change,|Sm|max, with H = 12 kOe, of the alloys was around 1 J·kg−1K−1 at room temperature. Onthe other hand, the full width at half maximum the entropy-change peak was quite large, 85 K,which was suitable for applications in magnetic refrigerators at room temperature.
( Dang Hai Dang Nguyen ),( Sung-hoon Park ),( Phuong Lan Tran ),( Jung-wan Kim ),( Quang Tri Le ),( Winfried Boos ),( Jong-tae Park ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.3
We first confirmed the involvement of MalQ (4-α-glucanotransferase) in Escherichia coli glycogen breakdown by both in vitro and in vivo assays. In vivo tests of the knock-out mutant, ΔmalQ, showed that glycogen slowly decreased after the stationary phase compared to the wild-type strain, indicating the involvement of MalQ in glycogen degradation. In vitro assays incubated glycogen-mimic substrate, branched cyclodextrin (maltotetraosyl-β-CD: G4-β-CD) and glycogen phosphorylase (GlgP)-limit dextrin with a set of variable combinations of E. coli enzymes, including GlgX (debranching enzyme), MalP (maltodextrin phosphorylase), GlgP and MalQ. In the absence of GlgP, the reaction of MalP, GlgX and MalQ on substrates produced glucose-1-P (glc-1-P) 3-fold faster than without MalQ. The results revealed that MalQ led to disproportionate G4 released from GlgP-limit dextrin to another acceptor, G4, which is phosphorylated by MalP. In contrast, in the absence of MalP, the reaction of GlgX, GlgP and MalQ resulted in a 1.6-fold increased production of glc-1-P than without MalQ. The result indicated that the G4-branch chains of GlgP-limit dextrin are released by GlgX hydrolysis, and then MalQ transfers the resultant G4 either to another branch chain or another G4 that can immediately be phosphorylated into glc-1-P by GlgP. Thus, we propose a model of two possible MalQ-involved pathways in glycogen degradation. The operon structure of MalP-defecting enterobacteria strongly supports the involvement of MalQ and GlgP as alternative pathways in glycogen degradation.
Two New Triterpene Glycosides from the Vietnamese Sea Cucumber Holothuria scabra
Dang, Nguyen Hai,Thanh, Nguyen Van,Kiem, Phan Van,Huong, Le Mai,Minh, Chau Van,Kim, Young-Ho 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.11
Two new triterpene glycosides, namely holothurin $A_3$ (1) and $A_4$ (2) were isolated from the methanol extract of the sea cucumber, Holothuria scabra, with their structures elucidated from the spectroscopic evidence (1D NMR, 20 NMR, ESI-MS and HRESI-MS). Compounds 1 and 2 were found to be strongly cytotoxic to both cancer cell lines, KB and Hep-G2, with 50% inhibitory concentrations $(IC_{50})$ of 0.87 and $0.32{\mu}g/mL$ (for compound 1) and of 1.12 and $0.57{\mu}g/mL$ (for compound 2), respectively.
The Role of Education in Young Household Income in Rural Vietnam
NGUYEN, Hai Dang,HO, Kim Huong,CAN, Thi Thu Huong Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.2
The purpose of the research is to evaluate how education influences the income of household heads, who are young adult in rural Vietnam. In order to examine the impact of education on the households where their heads are young adults, in this paper, the authors employ two research methods. First, ordinary least squares (OLS) regression is used to study the impact of education on different groups of income; second, quantile regression is applied to find out how education influences the income of households. The dataset includes a survey of 800 young households aged between18 and 35 who are the head of agricultural farms in rural areas. The findings indicate that education has a positive impact on income of young households. Furthermore, the results prove that the longer schooling years, the higher income youth can attain. The results showed that, at the survey time (Sep 2019), the average monthly income of rural young adults who are joining the production process shows a big gap between low and high incomes. Moreover, the study has revealed that other factors positively affect the incomes, namely, joining job-related associations, land resource, hired labour, hi-tech application as well as extension of producing unit.
Key Determinants for Users Intention to Use Smarthome Devices in Vietnam
Nguyen, Thi-Hong-Linh,Duong, Minh-Hung,Nguyen, Hai-Dang,Vo, Dang-HongNgan,Vu, Duy-Phuong-Trinh,Le, Hoanh-Su Korea Multimedia Society 2018 The journal of multimedia information system Vol.5 No.4
Smarthome is one of the remarkable fields of the industrial revolution 4.0, which are popular in many countries such USA, EURO, Japan and Korea. However, how Vietnamese people are considering and having intension to use smarthome devices is still a question for marketers and researchers. This study develops a comprehensive research model that can explain potential customers' behavioral intentions to adopt and use Smarthome services in Viet Nam and figure which key factors affect the intention. This study proposes and validates a new theoretical model that extends the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2). The model consists of eight factors that affect one element (Behavioral Intention), specifically: Habits, Perceived usefulness, Perceived ease of use, Trust, Innovativeness Personal, Perceived value, Hedonic motivations and Social influences. Data were collected from 304 Vietnamese citizens by sending the email to survey questionnaire, direct contact with the experienced smarthome users. Through regression analysis, data from samples were analysed with SPSS 20 software and verification of hypotheses, the results show the key determinants affecting the intention to use smarthome appliances in Vietnam: Perceived Value, Social Influence, Perceived Usefulness, Perceived Ease of Use and Trust. From this result, several recommendations have been suggested to to smarthome devices vendors and marketer to improve products as well as marketing approaches to meet customer needs.