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South Korea

Chae C.,Dong - A University | Kim J.H.,BK | Kim J.H.,Sungkyunkwan University | Kim J.M.,BK | And 3 more authors.
Journal of Materials Chemistry | Year: 2012

An ordered mesoporous carbon (OMC) with a nanorod-shaped morphology and enhanced graphitic character was employed as an ideal support for MnO x (major phase of Mn 3O 4 with a small portion of MnO) nanocrystals which possess a high theoretical conversion capacity as a Li-ion battery anode. The MnO x/OMC nanocomposite was prepared by a simple wet-impregnation of Mn(NO 3) 2 aqueous solution onto OMC nanorods followed by thermal treatment at 450 °C in an Ar flow. The electrochemical properties of MnO x/OMC were investigated in comparison to those of bare OMC and a commercial graphite as an anode for Li-ion batteries. Transmission electron microscopy, scanning electron microscopy, X-ray diffraction, N 2 adsorption-desorption analysis, X-ray photoelectron spectroscopy, and thermogravimetric analysis revealed that 3-30 nm MnO x nanocrystals at a high loading of 68.4 wt% were formed and well dispersed in the pore structure of OMC nanorods. The MnO x/OMC exhibited a high reversible capacity (>950 mAh g -1) after 50 deep charge-discharge cycles with excellent cycling stability, Coulombic efficiency and rate capability. As an anode for Li-ion batteries, the incorporation of insulating high density MnO x nanocrystals into OMC nanorods showed synergistic benefits of high volumetric capacity as well as specific capacity, and small redox voltage hysteresis compared to OMC nanorods. © 2012 The Royal Society of Chemistry.


Park J.H.,University of Seoul | Kim J.M.,BK | Kim J.M.,Sungkyunkwan University | Jurng J.,Korea Institute of Science and Technology | And 5 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2013

Benzene is one of the target compounds to be removed from air owing to its carcinogenicity. In this study, benzene oxidation with ozone over a MnO x/KIT-6 catalyst was carried out for the first time. MnO x/KIT-6 was synthesized using two different Mn precursors: Mn acetate and Mn nitrate. The characteristics of the synthesized catalysts were examined by X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction, Brunauer-Emmett-Teller (BET) surface area, and N2 adsorption-desorption. The catalytic activity was found to be dependent on the amount of ozone consumed and the dispersion and reducibility of MnOx on the catalyst surface. Copyright © 2013 American Scientific Publishers All rights reserved.


Park B.,BK | Yang Y.-M.,BK | Choi B.-J.,Yonsei University | Kim M.S.,Wonkwang University | Shin D.M.,BK
Korean Journal of Physiology and Pharmacology | Year: 2013

Receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis is accompanied by intracellular Ca2+ mobilization in a form of oscillations, which plays essential roles by activating sequentially Ca 2+ /calmodulin-dependent protein kinase, calcineurin and NFATc1, necessary in the osteoclast differentiation. However, it is not known whether Ca2+ mobilization which is evoked in RANKL-independent way induces to differentiate into osteoclasts. In present study, we investigated Ca 2+ mobilization induced by aluminum fluoride (AlF4 .), a G-protein activator, with or without RANKL and the effects of AlF4 . on the osteoclastogenesis in primary cultured mouse bone marrow-derived macrophages (BMMs). We show here that AlF4 . induces intracellular Ca2+ concentration ([Ca2+]i) oscillations, which is dependent on extracellular Ca2+ influx. Notably, co-stimulation of AlF4 . with RANKL resulted in enhanced NFATc1 expression and formation of tartrate-resistant acid phosphatase (TRAP) positive multinucleated cells. Additionally, we confirmed that mitogen-activated protein kinase (MAPK) is also activated by AlF4 .. Taken together, these results demonstrate that G-protein would be a novel modulator responsible for [Ca2+]i oscillations and MAPK activation which lead to enhancement of RANKL-mediated osteoclastogenesis.


Lee Y.-H.,BK | Lee N.-H.,BK | Bhattarai G.,BK | Kim G.-E.,BK | And 2 more authors.
Oral Diseases | Year: 2013

Objectives: Heme oxygenase-1 (HO-1) is contributed to odontoblast differentiation in human dental pulp cells (HDPCs). In this study, pachymic acid from mushroom Formitopsis niagra is examined to determine whether it affects pulpal inflammation and promotes odontogenesis via HO-1 gene expression. Materials and Methods: The HDPCs were given H2O2 for inflammation. The anti-inflammatory character and odontoblast differentiation by pachymic acid were analyzed by Western blotting, alkaline phosphatase activity, and alizarin red S staining. To understand the mechanism of pachymic acid via HO-1 induction, the cells were treated with zinc protoporphyrin IX (ZnPP: HO-1 inhibitor). Results: H2O2 induced pulp inflammation and disturbed odontoblast differentiation. However, the HDPCs treated with pachymic acid affected anti-inflammatory effect and induction of odontoblast differentiation through increasing HO-1 expression. In addition, pachymic acid has potent cytoprotection and mineralization under H2O2 treatment. Furthermore, pachymic acid significantly suppressed nuclear factor-kappa B (NF-κB) translocation into nucleus and induced NE-E2-related factor-2 (Nrf2) translocation into nucleus. Overall, NF-κB and Nrf2 translocation were regulated by the HO-1 pathway. Conclusions: The pachymic acid showed anti-inflammatory function and odontoblast differentiation via HO-1 pathway. These results suggested that pachymic acid may be applicable for prevention of oral inflammation or to improve dentin mineralization against several stresses. © 2012 John Wiley & Sons A/S.


Kim M.-J.,Kyung Hee University | El-Fiqi A.,BK | El-Fiqi A.,Dankook University | Yun H.-M.,Kyung Hee University | And 7 more authors.
International Journal of Nanomedicine | Year: 2016

Therapeutically relevant design of scaffolds is of special importance in the repair and regeneration of tissues including dentin and pulp. Here we exploit nanofiber matrices that incorporate bioactive glass nanoparticles (BGNs) and deliver the odontogenic drug dexamethasone (DEX) to stimulate the odontogenic differentiation of human dental pulp cells (HDPCs). DEX molecules were first loaded onto the BGN, and then the DEX-BGN complex was incorporated within the biopolymer nanofiber matrix through electrospinning. The release of DEX continued over a month, showing a slow releasing profile. HDPCs cultured on the DEX-releasing BGN matrices were viable, proliferating well up to 14 days. The odontogenic differentiation, as assessed by alkaline phosphatase activity, mRNA expression of genes, and mineralization, was significantly stimulated on the matrices incorporating BGN and further on those releasing DEX. The DEX-releasing BGN matrices highly upregulated the expression of the integrin subsets α1, α5, and β3 as well as integrin downstream signaling molecules, including focal adhesion kinase (FAK), Paxillin, and RhoA, and activated bone morphogenetic protein mRNA and phosphorylation of Smad1/5/8. Furthermore, the DEX-releasing BGN-matrices stimulated Akt and mammalian target of rapamycin (mTOR), which was proven by the inhibition study. Collectively, the designed therapeutic nanofiber matrices that incorporate BGN and deliver DEX were demonstrated to promote odontogenesis of HDPCs, and the integrins, bone morphogenetic protein, and mTOR signaling pathways are proposed to be the possible molecular mechanisms. While further in vivo studies are still needed, the DEX-releasing bioactive scaffolds are considered as a potential therapeutic nanomatrix for regenerative endodontics and tissue engineering. © 2016 Lim et al.

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