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EVOLUTIONARY STATUS OF 85 PEGASI
Bach, K.,Lee, J.,Demarque, P.,Kim, Y.-C. IOP Publishing 2009 The Astrophysical journal Vol.703 No.1
<P>We have investigated the evolutionary status of the visual binary 85 Peg (HD 224930) using a high-resolution spectroscopic analysis and the astrometric calibration of the stellar parameters. In spite of well-determined stellar parameters from HIPPARCOS astrometry and from spectroscopy, 85 Peg has for a long time revealed peculiar properties when attempts have been made to combine an evolutionary model with observation. There has been a chronic problem of the mass ratio of the two components when comparing 85 Peg's dynamical properties to the photometric magnitude difference. Moreover, 85 Peg has been suspected to have unique characteristics in its chemical composition. In order to determine accurate spectroscopic abundances, we have obtained high-resolution echelle spectra for 85 Peg. From our elemental analysis, we found that 85 Peg is alpha-enhanced with respect to the scaled solar abundance by a factor of 2. We then produced, within the framework of the standard stellar theory, grids of stellar model using the most recent observational results. To avoid many-fold degeneracy among physical quantities, a statistical minimization test was carried out between theoretical model grids. Enforcing consistency between the modeling and statistical constraints, we derived a reliable set of physical parameters and confirmed the trinarity of the system. In the context of asteroseismology, the theoretical frequency spectrum of 85 Peg was calculated. 85 Peg A is expected to have a first order spacing Delta nu similar to 165 mu Hz at the reference frequency nu(0) = 790 mu Hz.</P>
Bach, Long Giang,Cao, Xuan Thang,Quynh, Bui Thi Phuong,Ho, Van Thi Thanh,Lim, Kwon Taek Informa UK (TaylorFrancis) 2017 MOLECULAR CRYSTALS AND LIQUID CRYSTALS - Vol.644 No.1
<P>In this study, a facile method for synthesis of conducting polymer/inorganic oxide hybrid nanocomposites, the poly(N-vinylcar bazole)/Titanium Dioxide (PVK-g-TiO2), was successfully developed via direct facile esterification reaction under extremely mild conditions. The TiO2 nanoparticles (TiO2 NPs) were first modified by 3-glycidoxypropyl trimethoxysilane in order to prepare the epoxy groups functionalized TiO2 NPs, followed by refluxing with ethanol solution of hydrochloric acid to convert the epoxy groups into alkyl-hydroxyl units. A sufficient amount of PVK was then grafted onto the as-modified TiO2 NPs via esterification reaction between the alkyl-hydroxyl units at the nanoparticle surface and the carboxyl-terminated PVK chains. Fourier transform infrared spectroscopy, Energy dispersive X-Ray, X-ray diffraction and thermogravimetric analysis were used to study the chemical and physical properties in surface functionalities.</P>
Synthesis and biological activity of new phthalimides as potential anti-inflammatory agents
Bach, D.H.,Liu, J.Y.,Kim, W.K.,Hong, J.Y.,Park, S.H.,Kim, D.,Qin, S.N.,Luu, T.T.T.,Park, H.J.,Xu, Y.N.,Lee, S.K. Elsevier/Pergamon 2017 Bioorganic & medicinal chemistry Vol.25 No.13
The overproduction of nitric oxide (NO) plays an important role in a variety of pathophysiological processes, including inflammation. Therefore, the suppression of NO production is a promising target in the design of anti-inflammatory agents. In the present study, a series of phthalimide analogs was synthesized, and their anti-inflammatory activities were evaluated using lipopolysaccharide (LPS)-stimulated NO production in cultured murine macrophage RAW264.7 cells. A structure-activity relationship study showed that the free hydroxyl group at C-4 and C-6 and the bulkiness of the N-substituted alkyl chain are associated with biological activity. Among the series of phthalimide derivatives, compound IIh exhibited potent inhibitory activity, with an IC<SUB>50</SUB> value of 8.7@?g/mL. Further study revealed that the inhibitory activity of compound IIh was correlated with the down-regulation of the mRNA and protein expression of LPS-stimulated inducible nitric oxide synthase (iNOS). Compound IIh also suppressed the induction of the pro-inflammatory cytokines tumor necrosis factor-α and interleukin-1β in LPS-stimulated RAW 264.7 cells. The anti-inflammatory activity of compound IIh was also found to be associated with the suppression of the Toll-like receptor (TLR)4 signaling pathway by down-regulating the activation of interferon regulatory factor 3 (IRF-3) and interferon-β and signal transducer expression. These findings demonstrate that novel phthalimides might be potential candidates for the development of anti-inflammatory agents.
The Dominant Role of Forkhead Box Proteins in Cancer
Bach, Duc-Hiep,Long, Nguyen Phuoc,Luu, Thi-Thu-Trang,Anh, Nguyen Hoang,Kwon, Sung Won,Lee, Sang Kook MDPI 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.10
<P>Forkhead box (FOX) proteins are multifaceted transcription factors that are significantly implicated in cancer, with various critical roles in biological processes. Herein, we provide an overview of several key members of the FOXA, FOXC, FOXM1, FOXO and FOXP subfamilies. Important pathophysiological processes of FOX transcription factors at multiple levels in a context-dependent manner are discussed. We also specifically summarize some major aspects of FOX transcription factors in association with cancer research such as drug resistance, tumor growth, genomic alterations or drivers of initiation. Finally, we suggest that targeting FOX proteins may be a potential therapeutic strategy to combat cancer.</P>
A facile route towards the synthesis of polystyrene/zinc oxide nanocomposites.
Bach, Long Giang,Islam, M Rafiqul,Kim, Yong Hun,Seo, Sung Deok,Park, Chan,Kim, Hyun Gyu,Lim, Kwon Taek American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.1
<P>ZnO nanoparticles were covalently wrapped by polystyrene (PS) through surface thiol-lactam initiated radical polymerization using the grafting from approach. The surface of ZnO nanoparticles was initially modified by 3-mercapto propyltrimethoxysilane to afford thiol functionalized ZnO nanoparticles (ZnO-SH). The controlled radical polymerization of styrene (St) was subsequently accomplished by using an initiating system of ZnO-SH and butyrolactam. FT-IR, XPS, XRD, TGA, DSC, TEM and DLS were employed to investigate the chemical structure, morphology, thermal properties, the size and size distribution of nanocomposites. The dispersibility of ZnO nanoparticles was observed to be significantly improved upon functionalization by PS brushes. The controlled nature of the surface initiated thiol-lactam aided polymerization of St from the ZnO nanoparticles surface was confirmed by GPC analysis.</P>
Long-term Paradigm Analyses of Chlorophyll a and Water Quality in Reservoir Systems
Bach, Quang-Dung,Shin, Yong-Sik,Song, Eun-Sook The Korean Society of Limnology 2009 생태와 환경 Vol.38 No.1
During the period of past fifteen years (1992~2006), variations of chlorophyll a in relation with water quality in freshwater reservoirs were investigated. This study compared total nitrogen (TN), total phosphorus (TP), chlorophyll a, Secchi depth (SD) and total suspended solids (TSS) between terrestrial freshwater reservoir and coastal freshwater reservoir systems based on their location. Regression analyses (linear and non-linear regressions) were applied for all study sites to examine relationship and interaction of these factors in the freshwater systems from in-land to coasts. The results demonstrated that chlorophyll a was significantly correlated to total phosphorus ($R^2=0.94$, P<0.0001) and was remarkably related to TSS increase ($R^2=0.63$, P<0.0001) in the selected reservoirs. The TN : TP ratio in the reservoir systems was higher than Redfield ratio (16 : 1) indicating that the reservoirs are potentially experiencing P limitation. Water quality of coastal freshwater reservoir system was more significantly decreased than the reservoirs located in in-land during the past fifteen years. The strict management of nutrient discharge into freshwater systems should implemented in the coastal reservoirs since the freshwater is introduced into coastal estuarine systems.