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Sol-Gel 반응을 통한 Surlyn/유기 실리케이트 나노복합재료 제조 및 물성에 관한 연구
차종현,정희정,서길수 한국공업화학회 2003 응용화학 Vol.7 No.2
Transparent organic-inorganic hybrid material was synthesized via the sol-gel method using polyethylene-co-methacrylic acid(PEMA) ionomer and a metal alkoxide, tetraethylorthosilicae(TEOS). The resulting material was characterized using ^(29)Si solid-state nuclear magnetic resonance spectroscopy results prove that silica is formed via the sol-gel reaction. Scanning electron microscopy analysis (SEM) , transmission electron microscopy (TEM) studies indicate that silica particle size is in nanoscopic level (70nm average size), and silica nanoparticles are uniformly dispersed in the polymer matrix after the sol-gel process. Theremogravimetric analysis (TGA) results show that the silica content of the hybrid. The thermal stability of the ionomer increases after hybridization. Material testing machine of the hybrid shows that the stress of ionomer increase after the sol-gel reaction.
Preparation and Characterization of Soft Phase Magnetic α-Fe Nanoparticles by Different Methods
Cha, Hyun Gil,Kim, Young Hwan,Lee, Don Keun,Jeong, In Chul,Kwon, Hae Woong,Kang, Young Soo Scitec Publications Ltd. 2007 Solid State Phenomena Vol.119 No.-
<P>The magnetic α-Fe nanoparticles were carried out using two-preparation methods that include solution phase metal salt reduction and organometallic precursor decomposition. Under the different reaction conditions such as precursor and reaction time, the magnetic properties of α-Fe nanoparticles were studied. The size of nanoparticle was confirmed by transmission electron microscope (TEM) images. The magnetic properties were characterized with saturation magnetization(Ms) from hysteresis loop by vibrating sample magnetometer (VSM). The crystallinity and structure of α-Fe nanoparticles was investigated by X-ray diffraction (XRD).</P>
Photocatalysis: progress using manganese-doped hematite nanocrystals
Cha, Hyun Gil,Noh, Hyun Seok,Kang, Myung Jong,Kang, Young Soo The Royal Society of Chemistry 2013 New journal of chemistry Vol.37 No.12
<P>Manganese-doped hematite nanocrystals were synthesized by hydrothermal method and study on the activity of photocatalytic properties by different Mn ratio. From the crystal structure and optical study, the oxidation state of the manganese-doped hematite crystals was modulated by doping. The activity of samples (M1–M3) was tested by photodegradation of methyl orange dye in the presence of manganese-doped hematite as photocatalyst.</P> <P>Graphic Abstract</P><P>Manganese doping in hematite crystals leads to higher photocatalytic activity compared to pure hematite crystals. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3nj00478c'> </P>
Manual assembly of nanocrystals for enhanced photoelectrochemical efficiency of hematite film
Cha, Hyun Gil,Kang, Myung Jong,Hwang, In Chul,Kim, Hyunsung,Yoon, Kyung Byung,Kang, Young Soo The Royal Society of Chemistry 2015 Chemical communications Vol.51 No.29
<P>To improve the optoelectronic properties of hematite film as a photoanode, hematite film was orientated on the (012) plane by the secondary growth of organized microcrystals. The resultant film showed promising photoelectrochemical effects compared with a randomly oriented one, with a maximum photocurrent of 0.8 mA cm<SUP>−2</SUP> at 1.23 V <I>vs.</I> RHE under the illumination of 1 sun.</P> <P>Graphic Abstract</P><P>A (012) plane oriented hematite film with secondary growth of organized microcrystals showed promising photoelectrochemical efficiency compared with a randomly oriented film. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5cc00200a'> </P>
Cha, Hyun Gil,Kim, Young Hwan,Kim, Chang Woo,Kang, Young Soo,Kwon, Hae Woong TaylorFrancis 2007 Molecular Crystals and Liquid Crystals Vol.464 No.1
<P> Thermal decomposition process was applied to synthesize Fe3O4 and Nd2Fe14B nanoparticles which were prepared by reduction diffusion process for preparing exchange-coupled nanoparticles. The magnetic Nd2Fe14B nanoparticles used in this study as the starting materials were synthesized via metal oleate complex method. Also mechanical ball mill technique was applied to the mixture of magnetic Nd2Fe14B and α-Fe nanoparticles to build an exchange-coupled nanoparticle. The mixture of Nd2Fe14B/α-Fe of nanoparticle was confirmed by transmission electron microscopy (TEM). The crystal structure of nanoparticle was characterized by X-ray diffraction pattern (XRD). The magnetic properties were characterized with saturation magnetization from hysteresis loop by vibrating sample magnetometer (VSM). Thermogravimetry using a microbalance with magnetic field gradient positioned below the sample was used for the measurement of a thermomagnetic analysis (TMA) curve showing the downward magnetic force versus temperature.</P>
Magnetic property of Sm-Co nanoparticles prepared by solution phase metal salt reduction.
Cha, Hyun Gil,Kim, Chang Woo,Ji, Eun Sun,Kang, Dong In,Kang, Young Soo American Scientific Publishers 2009 Journal of Nanoscience and Nanotechnology Vol.9 No.12
<P>Sm-Co magnetic nanoparticles were successfully synthesized at high temperature above 680 degrees C in solution phase. The chemical composition was determined by EDX and it was found that the composition of as-synthesized Sm-Co magnetic nanoparticles showed less Sm content compared with the composition of starting materials. From TEM and FE-SEM measurements, the morphology of as-synthesized and heat-treated Sm-Co a magnetic nanoparticle was confirmed as hexagon and apatite crystal structure. Curie temperature was observed at around 680 degrees C correspond to SmCo5 phase. The magnetic property was measured by VSM and shows the ferromagnetic characteristics.</P>
Porphyromonas gingivalis accelerates atherosclerosis through oxidation of high-density lipoprotein
Hyun-Joo Kim,Gil Sun Cha,김형준,Eun-Young Kwon,이주연,최점일,주지영 대한치주과학회 2018 Journal of Periodontal & Implant Science Vol.48 No.1
Purpose: The aim of this study was to evaluate the ability of Porphyromonas gingivalis (P. gingivalis) to induce oxidation of high-density lipoprotein (HDL) and to determine whether the oxidized HDL induced by P. gingivalis exhibited altered antiatherogenic function or became proatherogenic. Methods: P. gingivalis and THP-1 monocytes were cultured, and the extent of HDL oxidation induced by P. gingivalis was evaluated by a thiobarbituric acid-reactive substances (TBARS) assay. To evaluate the altered antiatherogenic and proatherogenic properties of P. gingivalis-treated HDL, lipid oxidation was quantified by the TBARS assay, and tumor necrosis factor alpha (TNF-α) levels and the gelatinolytic activity of matrix metalloproteinase (MMP)-9 were also measured. After incubating macrophages with HDL and P. gingivalis, Oil Red O staining was performed to examine foam cells. Results: P. gingivalis induced HDL oxidation. The HDL treated by P. gingivalis did not reduce lipid oxidation and may have enhanced the formation of MMP-9 and TNF-α. P. gingivalis-treated macrophages exhibited more lipid aggregates than untreated macrophages. Conclusions: P. gingivalis induced HDL oxidation, impairing the atheroprotective function of HDL and making it proatherogenic by eliciting a proinflammatory response through its interaction with monocytes/macrophages.