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Search Results: 1 - 10 of 937 matches for " Myung Seob Khil "
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Effect of Addition of Soybean Oil and Gamma-Ray Cross-linking on the Nanoporous HDPE Membrane
Jong-Seok Park,Jong-Bae Choi,Hui-Jeong Gwon,Youn-Mook Lim,Myung Seob Khil,Phil-Hyun Kang,Young-Chang Nho
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/418021
Abstract: A nanoporous high-density polyethylene (HDPE) membrane was prepared by a wet process. Soybean oil and dibutyl phthalate (DBP) were premixed as codiluents, and gamma-rays were used for the cross-linking of HDPE. The pore volume of the nanoporous HDPE membranes with soybean oil was affected by the extracted amount of oil. The tensile strength of the membrane improved with an increasing absorbed dose up to 60 kGy, but decreased at 80 kGy due to severe degradation. The ionic conductivity of the nanoporous HDPE membrane did not really change with an increasing absorbed dose because the pores had already been formed before the gamma-ray radiation. Finally, the electrochemical stability of the HDPE membrane increased when the absorbed dose increased up to 60 kGy.
Characterization and Antimicrobial Property of Poly(Acrylic Acid) Nanogel Containing Silver Particle Prepared by Electron Beam
Jong-Bae Choi,Jong-Seok Park,Myung-Seob Khil,Hui-Jeong Gwon,Youn-Mook Lim,Sung-In Jeong,Young-Min Shin,Young-Chang Nho
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms140611011
Abstract: In this study, we developed a one step process to synthesize nanogel containing silver nanoparticles involving electron beam irradiation. Water-soluble silver nitrate powder is dissolved in the distilled water and then poly(acrylic acid) (PAAc) and hexane are put into this silver nitrate solution. These samples are irradiated by an electron beam to make the PAAc nanogels containing silver nanoparticles (Ag/PAAc nanogels). The nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). In addition, the particle size and zeta-potential were confirmed by a particle size analyzer (PSA). The antibacterial properties of the nanogels were evaluated by paper diffusion test. The Ag/PAAc nanogels had an antibacterial effect against Escherichia coli and Staphylococcus aureus. The nanogels also demonstrated a good healing effect against diabetic ulcer. The size of the Ag/PAAc nanogels decreased with increasing irradiation doses, and the absolute value of the zeta potential increased with increasing irradiation doses. Also, the Ag/PAAc nanogels exhibited good antibacterial activity against both Gram-negative and Gram-positive bacteria. In in vivo wound healing, the Ag/PAAc nanogels have a good healing effect.
Journey of Mesenchymal Stem Cells for Homing: Strategies to Enhance Efficacy and Safety of Stem Cell Therapy
Sung Keun Kang,Il Seob Shin,Myung Soon Ko,Jung Youn Jo,Jeong Chan Ra
Stem Cells International , 2012, DOI: 10.1155/2012/342968
Abstract: Human mesenchymal stem cells (MSCs) communicate with other cells in the human body and appear to “home” to areas of injury in response to signals of cellular damage, known as homing signals. This review of the state of current research on homing of MSCs suggests that favorable cellular conditions and the in vivo environment facilitate and are required for the migration of MSCs to the site of insult or injury in vivo. We review the current understanding of MSC migration and discuss strategies for enhancing both the environmental and cellular conditions that give rise to effective homing of MSCs. This may allow MSCs to quickly find and migrate to injured tissues, where they may best exert clinical benefits resulting from improved homing and the presence of increased numbers of MSCs. 1. Introduction The promise of regeneration is what has sparked an international effort to expand the field of stem cell research. In particular, the study of mesenchymal stem cells (MSCs) and their effects on cellular degenerative diseases is rapidly increasing. The role of MSCs in the modulation of the immune response, immune system activity, and the body’s response to inflammation and disease has been widely studied for many years [1–5]. Multiple studies have demonstrated that cultured MSCs have the ability to differentiate into bone and cartilage [6, 7] as well as other cell types and tissues both in vitro and in vivo [2, 6, 8]. Among other researchers, Ankrum and Karp demonstrated that MSCs differentiate into osteocytes, adipocytes, neural cells, and vascular endothelial cells [2]. Recent research, however, has shown that the environment plays a crucial role in limiting or expanding the differentiation capacity of MSCs [9–13]. Lavasani et al. [13] demonstrated that muscle stem cells from young mice conferred significant lifespan and healthspan extension in progeroid mice, which have stem cells defective in proliferation and multilineage differentiation. Furthermore, microenvironmental changes regulate the potential of MSCs to differentiate into specific cell types [14–17], and this effect on differentiation seems to be characterized by a variety of factors not yet well understood, such as the length of telomeres of cells in the microenvironment [10, 18]. While bone marrow MSCs (BMMSCs) were shown to have a decreased lifespan, rate of population doubling time [19], actual bone formation as patient age increased [14], adipose tissue-derived MSCs (AdMSCs) do not appear to undergo the same senescence pattern as BMMSCs [10, 18]. Mirsaidi et al. [18] demonstrated that murine
N-hexanoyl chitosan stabilized magnetic nanoparticles: Implication for cellular labeling and magnetic resonance imaging
Shanta R Bhattarai, Remant B Kc, Sun Y Kim, Manju Sharma, Myung S Khil, Pyoung H Hwang, Gyung H Chung, Hak Y Kim
Journal of Nanobiotechnology , 2008, DOI: 10.1186/1477-3155-6-1
Abstract: Magnetic particles ranging from the nanometer to micrometer scale are being used in an increasing number of medical applications. The important properties of magnetic particles for medical applications are nontoxicity, biocompatibility, injectability, and high level accumulation in the target tissue or organ; the most important property among those mentioned above is nontoxicity. Magnetic nanoparticles offer attractive and versatile applications in the field of biotechnology, such as DNA and RNA separation, cell separation, drug delivery system (DDS), magnetic resonance imaging (MRI), and hyperthermia [1-6]. For these applications, magnetic iron oxides such as Fe3O4 or gamma-Fe2O3 are employed as a magnetic phase because they are stable and harmless to the living bodies. To make them bind to a biological entity, their surfaces are usually modified with an appropriate compound such as polyethyleneglycol (PEG) or streptavidin. Polymers like poly-L-lysine (PLL), poly ethylene imide (PEI) and dextran, and recently chitosan [6] has been used as a stabilizer (coating agent) for iron oxide nanoparticles so as to improve the nanoparticle's biocompatibility and injectability. However, high-level accumulation in the target tissue or organ and cytotoxicity; the most important property of the nanoparticles is remains to be intact.More or less to improve limitations stated above, several derivatives of chitosan have been proposed based on reactions with the free amino groups. Our research group already investigated the hydrophobic modification of natural chitosan by using three different acyl chlorides (hexanoyl, octanoyl and myristoyl chloride) so as to improve its aqueous solubility and subsequently used them for stabilization of metalic nanoparticles [7-9]. In this paper, we have selected the hexanoyl chloride modified chitosan stabilized iron oxide nanoparticles (Nac-6-IOPs or simply MC-IOPs) as a material of interest and demonstrated its biomedical application like cellular
Environmental Dependence of Local Luminous Infrared Galaxies
Ho Seong Hwang,David Elbaz,Jong Chul Lee,Woong-Seob Jeong,Changbom Park,Myung Gyoon Lee,Hyung Mok Lee
Physics , 2010, DOI: 10.1051/0004-6361/201014807
Abstract: We study the environmental dependence of local luminous infrared galaxies (LIRGs) and ultraluminous infrared galaxies (ULIRGs) found in the Sloan Digital Sky Survey (SDSS) data. The LIRG and ULIRG samples are constructed by cross-correlating spectroscopic catalogs of galaxies of the SDSS Data Release 7 and the Infrared Astronomical Satellite Faint Source Catalog. We examine the effects of the large-scale background density (Sigma_5), galaxy clusters, and the nearest neighbor galaxy on the properties of infrared galaxies (IRGs). We find that the fraction of LIRGs plus ULIRGs among IRGs (f_(U)LIRGs) and the infrared luminosity (L_IR) of IRGs strongly depend on the morphology of and the distance to the nearest neighbor galaxy: the probability for an IRG to be a (U)LIRG (f_(U)LIRGs) and its L_IR both increase as it approaches a late-type galaxy, but decrease as it approaches an early-type galaxy (within half the virial radius of its neighbor). We find no dependence of f_(U)LIRGs on the background density (surface galaxy number density) at fixed stellar mass of galaxies. The dependence of f_(U)LIRGs on the distance to galaxy clusters is also found to be very weak, but in highest-density regions such as the center of galaxy clusters, few (U)LIRGs are found. These environmental dependence of LIRGs and ULIRGs and the evolution of star formation rate (SFR)-environment relation from high redshifts to low redshifts seem to support the idea that galaxy-galaxy interactions/merging play a critical role in triggering the star formation activity of LIRGs and ULIRGs.
Effects of Expanded Human Adipose Tissue-Derived Mesenchymal Stem Cells on the Viability of Cryopreserved Fat Grafts in the Nude Mouse
Myung-Soon Ko, Ji-Youl Jung, Il-Seob Shin, Eun-Wha Choi, Jae-Hoon Kim, Sung Keun Kang, Jeong Chan Ra
International Journal of Medical Sciences , 2011,
Abstract: Adipose-derived mesenchymal stem cells (AdMSCs) augment the ability to contribute to microvascular remodeling in vivo and to modulate vascular stability in fresh fat grafts. Although cryopreserved adipose tissue is frequently used for soft tissue augmentation, the viability of the fat graft is poor. The effects of culture-expanded human adipose tissue-derived mesenchymal stem cells (hAdMSCs) on the survival and quality of the cryopreserved fat graft were determined. hAdMSCs from the same donor were mixed with fat tissues cryopreserved at -70°C for 8 weeks and injected subcutaneously into 6-week-old BALB/c-nu nude mice. Graft volume and weight were measured, and histology was evaluated 4 and 15 weeks post-transplantation. The hAdMSC-treated group showed significantly enhanced graft volume and weight. The histological evaluation demonstrated significantly better fat cell integrity compared with the vehicle-treated control 4 weeks post-transplantation. No significant difference in graft weight, volume, or histological parameters was found among the groups 15 weeks post-transplantation. The hAdMSCs enhanced the survival and quality of transplanted cryopreserved fat tissues. Cultured and expanded hAdMSCs have reconstructive capacity in cryopreserved fat grafting by increasing the number of stem cells.
Mid-Infrared Luminosity Function of Local Star-Forming Galaxies in the NEP-Wide Survey Field of AKARI
Seong Jin Kim,Hyung Mok Lee,Woong-Seob Jeong,Tomotsugu Goto,Hideo Matsuhara,Myungshin Im,Hyunjin Shim,Min Gyu Kim,Myung Gyoon Lee
Physics , 2015, DOI: 10.1093/mnras/stv2006
Abstract: We present mid-infrared (MIR) luminosity functions (LFs) of local star-forming (SF) galaxies in the AKARI NEP-Wide Survey field. In order to derive more accurate luminosity function, we used spectroscopic sample only. Based on the NEP-Wide point source catalogue containing a large number of infrared (IR) sources distributed over the wide (5.4 sq. deg.) field, we incorporated the spectroscopic redshift data for about 1790 selected targets obtained by optical follow-up surveys with MMT/Hectospec and WIYN/Hydra. The AKARI continuous 2 to 24 micron wavelength coverage as well as photometric data from optical u band to NIR H-band with the spectroscopic redshifts for our sample galaxies enable us to derive accurate spectral energy distributions (SEDs) in the mid-infrared. We carried out SED fit analysis and employed 1/Vmax method to derive the MIR (8, 12, and 15 micron rest-frame) luminosity functions. We fit our 8 micron LFs to the double power-law with the power index of alpha= 1.53 and beta= 2.85 at the break luminosity. We made extensive comparisons with various MIR LFs from several literatures. Our results for local galaxies from the NEP region are generally consistent with other works for different fields over wide luminosity ranges. The comparisons with the results from the NEP-Deep data as well as other LFs imply the luminosity evolution from higher redshifts towards the present epoch.
(-)-Epigallocatechin-3-Gallate Protects against NO-Induced Ototoxicity through the Regulation of Caspase- 1, Caspase-3, and NF-κB Activation
Su-Jin Kim, Jeong-Han Lee, Beom-Su Kim, Hong-Seob So, Raekil Park, Noh-Yil Myung, Jae-Young Um, Seung-Heon Hong
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043967
Abstract: Excessive nitric oxide (NO) production is toxic to the cochlea and induces hearing loss. However, the mechanism through which NO induces ototoxicity has not been completely understood. The aim of this study was to gain further insight into the mechanism mediating NO-induced toxicity in auditory HEI-OC1 cells and in ex vivo analysis. We also elucidated whether and how epigallocatechin-3-gallate (EGCG), the main component of green tea polyphenols, regulates NO-induced auditory cell damage. To investigate NO-mediated ototoxicity, S-nitroso-N-acetylpenicillamine (SNAP) was used as an NO donor. SNAP was cytotoxic, generating reactive oxygen species, releasing cytochrome c, and activating caspase-3 in auditory cells. NO-induced ototoxicity also mediated the nuclear factor (NF)-κB/caspase-1 pathway. Furthermore, SNAP destroyed the orderly arrangement of the 3 outer rows of hair cells in the basal, middle, and apical turns of the organ of Corti from the cochlea of Sprague–Dawley rats at postnatal day 2. However, EGCG counteracted this ototoxicity by suppressing the activation of caspase-3/NF-κB and preventing the destruction of hair cell arrays in the organ of Corti. These findings may lead to the development of a model for pharmacological mechanism of EGCG and potential therapies against ototoxicity.
The Aesthetic Turn in Everyday Life in Korea  [PDF]
Kwang Myung Kim
Open Journal of Philosophy (OJPP) , 2013, DOI: 10.4236/ojpp.2013.33054
Abstract: We are living in the transitional age from the rational, analytical, and scientific to the cultural, sensitive, and aesthetic. The aesthetics of everyday life lies at the center of this age. There is no boundary between art and life in contemporary art. Almost all the contents and objects of everyday life became a work of art in the condition of searching for the aesthetic. Since aesthetic theory was shifted from the artist-centered or a work of art-centered to the audience, spectator or beholder-centered, art and everyday life were more closely related to each other. So aesthetic attention or attitude is not specific to art, but pervasive broadly in everyday life. We can embrace the aesthetic concerns in everything we make and use every day. In the long tradition of Korean art, it can be seen that aesthetic consciousness is steeped in day-to-day life as well as the arts. I want to consider the problems of everydayness, Korean aesthetic consciousness in daily life, and contemplation in the aesthetic consciousness. Korean art was characterized by its “lack of refinement” and “nonchalance”. The characteristics of Korean art as the qualities of “technique without technique”, “Planning without plan”, “asymmetrical symmetry” have dominated the everyday consciousness of Korean people as well as Korean art. The extension of aesthetic emotion through experimentation shows us the change of aesthetic consciousness as a new possibility of interpretation. We stand in an urgent situation of the need for a new theory of art. It will be related to the future of aesthetics. For this reason, I think we have to consider the meaning of the aesthetic turn in everyday life.
Problems and Prospects of Geoaesthetics  [PDF]
Kwang Myung Kim
Open Journal of Philosophy (OJPP) , 2015, DOI: 10.4236/ojpp.2015.51001
Abstract: Geoaesthetics is the project of making aesthetic sense of nature through geological phenomena. The aesthetic appreciation of nature has recently become urgent because of the serious influence of the natural environment on human beings. The author’s geoaesthetical research is categorized into three problems: art in geology or geology in the arts as the close relationship between art and geology, geological cognition of nature and natural cognition in environmental aesthetics, and the geoaesthetical approach through works of art. Geologic forces and processes have become significant materials for aesthetic sensations. Based on the geoaesthetic perspective, the author explores the ultimate purpose of art as a return to natural order. It seems partly to be related to the ontological problem of art. Here we can feel earthly dynamics, universal calmness, and the contemplative atmosphere simultaneously.
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