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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.
Presence of β-Amylase in Ramie Leaf and its Anti-staling Effect on Rice Cake
Dang Hai Dang Nguyen,Phuong Lan Tran,하현숙,이진실,홍완수,Quang Tri Le,오병철,박성훈 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.1
Presence of β-amylase in ramie leaf and its anti-staling effect on starch-based foods were assessed. The ammonium sulfate fractionate (80% saturation) of the ramie leaf extracts showed a β-amylase activity, giving maltose (Glc2) as a major product, exclusively, when incubating with maltopentaose (Glc5) or soluble starch at 45oC, pH 6.0. The starch-based food product (rice cake) prepared with freeze-dried ramie leaf enzyme revealed that the linear maltooligosaccharides ranging from Glc2 to Glc6 significantly increased and the shorter branch chains (DP<15) of amylopectin increased whereas the longer branch chains (DP>16) decreased in the product. These results demonstrated that maltosyl residue was released from the non-reducing end of the longer branch chains of amylopectin by β-amylase. The ramie leaf-treatment sample significantly reduced the retrogradation rate during 48 h storage at 4℃. As an alternative plant-origin enzyme, the ramie leaf β-amylase has potential for a novel anti-staling additive.
Camber effect on the stability and power performance of a right-swing hydrofoil turbine
Nguyen Le Dang Hai,Le Tuyen Quang,Jeong Dasom,고진환 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1
In this study, performance of a right-swing turbine with a cambered hydrofoil was analyzed by CFD numerical simulations to assess its stability and power efficiency. It is found from the analysis that the right-swing trajectory, which is close to the kinematics of flying or swimming creatures, has advantages over the left-swing trajectory in terms of stability with a slight loss of the power efficiency. A cambered hydrofoil can be utilized to offset this loss, but doing so negatively affects the stability at the turning positions of the flapping motion. Consequently, in order to guarantee stability and high efficiency of a right-swing hydrofoil turbine, camber shapes adjustable at the positions of flapping motion, which is an excellent feature of flight and swimming creatures, are mandatory. Eventually, the analysis results of this study will be utilized to develop a high-performance flapping hydrofoil turbine.
( 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
Nguyen Hai Dang,Nguyen Van Thanh,Phan Van Kiem,Le Mai Huong,Chau Van Minh,김영호 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.11
Two new triterpene glycosides, namely holothurin A3 (1) and A4 (2) were isolated from the methanol extract of the sea cucumber, Holothuria scabra, with their structures elucidated from the spectroscopic evidence (1D NMR, 2D 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 (IC50) of 0.87 and 0.32 µg/mL (for compound 1) and of 1.12 and 0.57 µg/mL (for compound 2), respectively.
Le-Phuc Nguyen,Yen Thi Hai Pham,Phuong Thuy Ngo,Tri Van Tran,Loc Vinh Tran,Nam Thi Hoai Le,Luong Huu Nguyen,Tung Thanh Dang,Duc Anh Nguyen,Marco Wenzel,David Hartmann,Karsten Gloe,Jan J. Weigand,Klaus 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.5
Acid leaching and a two-step solvent extraction procedure were developed to produce high purity mixture of La and Ce from iron-rich spent FCC catalyst discharged from Dzung Quat refinery (Vietnam). Acid leaching of the spent catalyst with 2M HNO3 and a solid-to-liquid ratio of 1/3 at 80 oC in 1 h dissolved almost 90% of La while 12% of Al and 25% of Fe were transferred to the leachate. The extraction of RE metals and main impurities such as Al and Fe by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) was investigated. Experiments showed that it was necessary to remove Fe before extracting RE and the optimum extraction conditions for a high recovery of RE while 0% of Al extraction were pH1, contact time=10min, and D2EHPA/TBP volume ratio= 4 : 1. At these conditions, the extraction yields of La(III) and Ce(III) were 72% and 89%, respectively. A two-step solvent extraction was developed to achieve a high purity of RE mixture, which included (1) the removal of impurity Fe by 25% (v/v) diisooctyl phosphinic acid (DiOPA) in n-octane for 140 min, (2) the extraction of rare earths by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) in n-octane for 10 min without the need for adjusting the pH of the leaching solution.
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.
Truong Giang Nguyen,Thanh Khiem Nguyen,Ham Hoi Nguyen,Hong Son Trinh,Tuan Hiep Luong,Minh Trong Nguyen,Van Duy Le,Hai Dang Do,Kieu Hung Nguyen,Van Minh Do,Quang Huy Tran,Cuong Thinh Nguyen 한국간담췌외과학회 2024 Annals of hepato-biliary-pancreatic surgery Vol.28 No.1
Backgrounds/Aims: Parenchymal-sparing anatomical hepatectomy (Ps–AH) based on portal ramification of the right anterior section (RAS) is a new technique to avoid unnecessarily transecting too much liver parenchyma, especially in cases of major anatomical hepatectomy. Methods: We prospectively assessed 26 patients with primary hepatic malignancies having undergone major Ps–AH based on portal ramification of the RAS from August 2018 to August 2022 (48 months). The perioperative indications, clinical data, intra-operative index, pathological postoperative specimens, postoperative complications, and follow-up results were retrospectively evaluated. Results: Among the 26 patients analyzed, there was just one case that had intrahepatic cholangiocarcinoma The preoperative level of α– Fetoprotein was 25.2 ng/mL. All cases (100%) had Child–Pugh A liver function preoperatively. The ventral/dorsal RAS was preserved in 19 and 7 patients, respectively. The mean surgical margin was 6.2 mm. The mean surgical time was 228.5 minutes, while the mean blood loss was 255 mL. In pathology, 5 cases (19.2%) had microvascular invasion, and in the group of HCC patients, 92% of all cases had moderate or poor tumor differentiation. Six cases (23.1%) of postoperative complications were graded over III according to the Clavien–Dindo system, including in three patients resistant ascites or intra-abdominal abscess that required intervention. Conclusions: Parenchymal-sparing anatomical hepatectomy based on portal ramification of the RAS to achieve R0-resection was safe and effective, with favorable short-term outcomes. This technique can be used widely in clinical practice.
Study on the Design of Underwater Chain Trencher
N. L. D. Hai(Nguyen Le Dang Hai),J. Kim,O S. Kwon,J. H. Ko 유공압건설기계학회 2019 유공압건설기계학회 학술대회논문집 Vol.2019 No.6
In this study, a design process for an underwater trencher is introduced. Design optimization based on genetic algorithm is applied to obtain an optimal design and then chain-sprocket selection is followed. The prototype is fabricated based on the design process and is successfully demonstrated.