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Promoting Effect of AlCl_3 on the Fe-catalyzed Dimerization of Bicyclo[2.2.1]hepta-2,5-diene
Nguyen, Mai Dao,Nguyen, Ly Vinh,Lee, Je-Seung,Han, Jeong-Sik,Jeong, Byung-Hun,Cheong, Min-Serk,Kim, Hoon-Sik,Kang, Ho-Jung Korean Chemical Society 2008 Bulletin of the Korean Chemical Society Vol.29 No.7
The activity of the catalytic system composed of Fe$(acetylacetonate)_3$ (Fe$(acac)_3$), triphenylphosphine, and diethylaluminum chloride for the dimerization of bicyclo[2.2.1]hepta-2,5-diene (2,5-norbornadiene, NBD) to produce hexacyclic endo-endo dimer (hexacyclo[$7.2.1.0^{2,8}.1^{3,7}.1^{5,13}.0^{4,6}$]tetradec-10-ene, Hnn) was significantly enhanced by the presence of $AlCl_3$, especially at the molar ratios of NBD/Fe$(acac)_3$ of 500. XPS analysis of the catalytic systems clearly demonstrates that $AlCl_3$ facilitates the reduction of Fe$(acac)_3$ to form active species, Fe(II) and Fe(0) species. The layer separation was observed when [BMIm]Cl was used along with $AlCl_3$, but catalyst recycle was not very successful.
Nguyen, Van Dao,Min, Byoung-Cheol,Kyung, Myung-Ok,Park, Jong-Tae,Lee, Byong Hoon,Choi, Chung-Hyo,Seo, Nam-Seok,Kim, Yong-Ro,Ahn, Dong Uk,Lee, Sung-Joon,Park, Cheon-Seok,Kim, Jung-Wan,Park, Kwan-Hwa John Wiley Sons, Ltd. 2009 Phytochemical analysis Vol.20 No.6
<P>Introduction – Kudzu root (Radix puerariae) is a rich source of isoflavones that are effective in preventing osteoporosis, heart disease and symptoms associated with menopause. The major isoflavonoids in kudzu root extracts were reported as puerarin, daidzin and daidzein. Recently, an unknown isoflavonoid (compound 1) was detected from one-year-old kudzu root cultivated in Vietnam.</P><P>Objective – To identify a novel compound 1 in kudzu root extract and determine the structure of the compound by ESI<SUP>+</SUP> TOF MS-MS, <SUP>1</SUP>H-, <SUP>13</SUP>C-NMR and enzymatic hydrolysis.</P><P>Methodology – Samples were prepared by extraction of one-year-old kudzu root with 50% ethanol and the isoflavonoids were purified using recycling preparative HPLC. Unknown compound 1 was detected using UV-light at 254 nm in TLC and HPLC analyses. The molecular weight of 1 was determined using a TOF mass spectrometer equipped with an electrospray ion source. The structure of 1 was determined from the <SUP>13</SUP>C and <SUP>1</SUP>H NMR spectra recorded at 100.40 and 400.0 MHz, respectively.</P><P>Results – ESI<SUP>+</SUP> TOF MS-MS analysis shows that 1 is a puerarin diglycoside. The interglycosidic linkage of diglycoside determined by <SUP>1</SUP>H-, <SUP>13</SUP>C-NMR, and enzymatic hydrolysis suggests that 1 has a glucosyl residue linked to puerarin by an α-1,6-glycosidic bond. This compound is the first naturally-occurring 8-[α-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl]daidzein in kudzu root. The concentration of glucosyl-α-1,6-puerarin in kudzu root was 2.3 mg/g as determined by HPLC.</P><P>Conclusion – The results indicate that puerarin diglycoside is one of the major isoflavonoids in kudzu root and has a significant impact on the preparation of highly water-soluble glycosylated puerarin. Copyright © 2009 John Wiley & Sons, Ltd.</P>
Flavonoid-mediated inhibition of SARS coronavirus 3C-like protease expressed in Pichia pastoris.
Nguyen, Thi Thanh Hanh,Woo, Hye-Jin,Kang, Hee-Kyoung,Nguyen, Van Dao,Kim, Young-Min,Kim, Do-Won,Ahn, Sul-Ah,Xia, Yongmei,Kim, Doman Kluwer Academic Publishers 2012 Biotechnology letters. Vol.34 No.5
<P>The 3C-like protease (3CL(pro)) of severe acute respiratory syndrome associated coronavirus (SARS-CoV) is vital for SARS-CoV replication and is a promising drug target. Recombinant 3CL(pro) was expressed in Pichia pastoris GS115 as a 42??kDa protein that displayed a K ( m ) of 15??±??2??관M with Dabcyl-KTSAVLQSGFRKME-Edans as substrate. Purified 3CL(pro) was used for inhibition and kinetic assays with seven flavonoid compounds. The IC(50) of six flavonoid compounds were 47-381??관M. Quercetin, epigallocatechin gallate and gallocatechin gallate (GCG) displayed good inhibition toward 3CL(pro) with IC(50) values of 73, 73 and 47??관M, respectively. GCG showed a competitive inhibition pattern with K ( i ) value of 25??±??1.7??관M. In molecular docking experiments, GCG displayed a binding energy of -14??kcal??mol(-1) to the active site of 3CL(pro) and the galloyl moiety at 3-OH position was required for 3CL(pro) inhibition activity.</P>
Kim, Dae Won,Huh, Eun Soo,Park, Sang Do,Nguyen, Ly Vinh,Nguyen, Mai Dao,Kim, Hoon Sik,Cheong, Minserk,Nguyen, Dinh Quan WILEY-VCH Verlag 2010 Advanced Synthesis & Catalysis Vol. No.
<P>The methoxycarbonylation reactions of aliphatic diamines with dimethyl carbonate are accelerated greatly in the presence of water. Theoretical investigations on the mechanistic aspects of the methoxycarbonylation of 1,6-hexanediamine strongly suggest that the hydroxide ion, generated in situ from the interaction of 1,6-hexanediamine with water, is an active catalytic species and plays a pivotal role in the rate-determining hydrogen abstraction step from the amino group.</P> <B>Graphic Abstract</B> <P> <img src='wiley_img/16154150-2010-352-2-3-ADSC200900699-content.gif' alt='wiley_img/16154150-2010-352-2-3-ADSC200900699-content'> </P>
Nguyen Thanh-Nho,Thai Huynh-Thuc,Le-Thi Anh-Dao,Do Minh-Huy,Le-Thi Huynh-Mai,Le Quang-Huy,Nguyen-Thi Kim-Sinh,Nguyen Cong-Hau 한국분석과학회 2023 분석과학 Vol.36 No.5
Aluminium (Al) is one of the major elements in rocks and its concentration can be varied, depending on different rock types as well as sources. The present study aimed to propose an analytical method based on the UV-Vis as a cheap, simple, and common instrument equipped in most laboratories for Al quantification in rocks after the microwave assisted acid digestion. The aluminone and 8-hydroxyquinoline were investigated for the colorimetric assay. The results show that the 8-hydroxyquinoline reagent was more favorable in terms of the minimized affects of the potential interferences present in the digested solutions, i.e., Fe3+, Si4+ and F–. The calibration curve was constructed from 0.10 mg/L to 3.00 mg/L with the goodness of linearity (R2 = 0.9996). The limits of detection and quantification (LOD and LOQ) were estimated, i.e., 0.029 mg/L and 0.087 mg/L, respectively. The 8-hydroxyquinoline was applied to real rock samples, demonstrating favorable precision (RSD = 0.34 %-1.8 %) and no remarkable differences were found compared to the inductively coupled plasma-mass spectrometry (ICP-MS) as a reference measurement approach.
Nguyen Ho Minh Duy,Tran Anh Tuan,Nguyen Hai Duong,Tran Anh Tuan,Nguyen Kim Dao,Atsuo Yoshitaka,Jin Young Kim,Seung Ho Choi,Pham The Bao 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.5
MRI and CT images are the most popular formats assisting a doctor in diagnosis and treatment, but highly accurate segmentation is a challenging problem due to intensity inhomogeneity and environmental noises. In this paper, we introduce an appropriate and effective automatic approach to facilitate this problem in two stages. In the first stage, skull region is removed from the brain by morphological active contour and level set process. Moreover, in level set process, some AI rules are defined on slice positions of brain to increase the accuracy. In the second stage, a modified EM method is performed on the resultant skull-stripping image to identify some candidate main regions of CSF (cerebro-spinal fluid), GM (gray matter), and WM (white matter). The candidate regions are then re-estimated into the proper CSF, GM, and WM through a Bayesian Estimation Process. The experimental results show that the proposed approach obtains a robust segmentation for IBSR, OASIS and Korean Hospital database. With the proposed AI-rules, the level set method gets good skull-stripping images regardless of MRI slice position in bran. Also, Bayesian postprocessing can improve the segmentation performance by 10~15% in CSF, GM and WM ratios compared the basic EM algorithm.
Nam, Nguyen-Hai,Huong, Tran Lan,Dung, Do Thi Mai,Dung, Phan Thi Phuong,Oanh, Dao Thi Kim,Park, Sang Ho,Kim, Kyungrok,Han, Byung Woo,Yun, Jieun,Kang, Jong Soon,Kim, Youngsoo,Han, Sang-Bae Informa UK Ltd. 2014 Journal of enzyme inhibition and medicinal chemist Vol.29 No.5
<P>Since the first histone deacetylase (HDAC) inhibitor (Zolinza®, widely known as suberoylanilide hydroxamic acid; SAHA) was approved by the Food and Drug Administration for the treatment of T-cell lymphoma in 2006, the search for newer HDAC inhibitors has attracted a great deal of interest of medicinal chemists worldwide. As a continuity of our ongoing research in this area, we designed and synthesized a series of 5-substitutedphenyl-1,3,4-thiadiazole-based hydroxamic acids as analogues of SAHA and evaluated their biological activities. A number of compounds in this series, for example, <I>N<SUP>1</SUP></I>-hydroxy-<I>N</I><SUP>8</SUP>-(5-(2-chlorophenyl)-1,3,4-thiadiazol-2-yl)octandiamide (<B>5b</B>), <I>N<SUP>1</SUP></I>-hydroxy-<I>N</I><SUP>8</SUP>-(5-(3-chlorophenyl-1,3,4-thiadiazol-2-yl)octandiamide (<B>5c</B>) and <I>N<SUP>1</SUP></I>-hydroxy-<I>N</I><SUP>8</SUP>-(5-(4-chlorophenyl)-1,3,4-thiadiazol-2-yl)octandiamide (<B>5d</B>), were found to possess potent anticancer cytotoxicity and HDAC inhibition effects. Compounds <B>5b</B>-<B>d</B> were generally two- to five-fold more potent in terms of cytotoxicity compared to SAHA against five cancer cell lines tested. Docking studies revealed that these hydroxamic acid displayed higher affinities than SAHA toward HDAC8.</P>
Social Capital and Migration: A Case Study of Rural Vietnam
Hong Thu NGUYEN,My Kim LE,Thi Thuy Dung NGUYEN,Vu Phuong Linh DAO,Ngoc Tien NGUYEN 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.1
To investigate the short-run effects of social capital on migration decisions of individuals in the rural areas of Vietnam, we conducted dataset mining and performed regression model analysis in the form of panel data. As control variables, we employed the variable of social capital, which is measured by an individual’s network, as well as demographic characteristics of individuals and households. We discovered that when a household is in financial distress, social networks such as linkages or asking for aid from others often enhance individual capacity. Individuals with a large social network outside of their immediate area are more inclined to relocate to the location where their connectors live. Individual participation and degree of participation in the organizational community, on the other hand, have little bearing on the likelihood of migration. In addition, this research examines theories and empirical research on the relationship between social capital and migration. Based on our research findings, we have recommended some measures to boost the efficiency of social capital and migration in rural areas of Vietnam through local government solutions.