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티타늄 상에 강유전성 barium titanate 박막 형성과 분극처리에 의한 유사체액 내에서의 calcium phosphate 생성 증진
박영준,이용렬,황규석,김은주,임용무,이기헌 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.2
This study was performed to fabricate a ferroelectric barium titanate (BaTiO₃, BTO) thin film on Ti substrate and to evaluate the effect of poling treatment for the improvement of calcium phosphate (Ca-P) formation. BTO thin-film was spin-coated on Ti substrate by dipping-pyrolysis technique using coating sol obtained by mixing Ba-naphthenate and Ti-naphthenate as starting substances. Pre-heating temperature of the BTO thin film was performed at 500℃ because organic-solvent was completely volatilized without any crystal growth, and the final heat treatment was performed at 600, 650, 700, 750, 800, 850℃, respectively. By repeating the coating and pre-heating procedure gor 20 times, homogeneous thin film of 0.7㎛ thickness could be fabricated, and it performed well during the poling treatment without breakdown. The final heating treatment of the BTO thin film at 750℃ produced a homogeneous crystalline structure without heterogeneous TiO₂formation, which was confirmed by field emission scanning electron microscope (FE-SEM) and X-ray diffraction analyser (XRD). An average grain size of 20∼30 ㎚ were confirmed by SEM observation. The final heat-treated BTO thin-films were polarized (Ep = 5 V/㎛) from 160℃ to 25℃ in heating chamber for 2 h. The negatively poled BTO thin film (N-BTO), non-poled BTO thin film (BTO), Ti substrate (Ti), and 600℃ heat-treated Ti (Ti-O) were immersed in SBF and Eagle's MEM solution for 15 days at 37℃. After the immersion period, the morphological and compositional changes of the surfaces were investigated using a FE-SEM and an energy dispersive X-ray spectrometer (EDX). After immersion in simulated body fluid (SBF), sodium chloride (Nacl) crystals were formed on Ti, Ti-O, and BTO surfaces due to anion adsorption (Cl), while Ca-P crystals were formed on N-BTO surfaces. We assumed that rapidly adsorded cations (Ca²□ ions) on the negatively charged surface at the initial stage acted as nuclei for the formation of Ca-P crystals. In MEM, sodium chloride (NaCl) was formed on Ti, and Ca-P layer including NaCl was formed on Ti-O. Weak and sparse Ca-P layers were formed on BTO, while thick, homogeneous, and dense Ca-P layer was formed on N-BTO, which was confirmed by FE-SEM and EDX. These results demonstrated that introducing a N-BTO on Ti is an effective method for the improvement of Ca-P formation in SBF and MEM. In conclusion, negatively charged ferroelectric BTO thin-film on Ti would improve the possibility of implant osseointegration.
강유전성 BaTiO₃의 분극처리에 의한 유사체액 내에서 Calcium Phosphate 생성
송종은,김은주,황규석,임용무,박영준 대한치과기재학회 2000 대한치과재료학회지 Vol.27 No.4
Barium titanate (BaTiO3; BTO) has wide application in industry, particularly in the manufacturing of dynamic random access memory chips, electro-optical switches, optical modulators, shutters, optical mixers, and sensors, owing to its ferroelectric and piezoelectric properties after poling treatment. There has recently been considerable interest in the properties of its role in osseointegration. In this study, we investigated the possibility of treating BTO by poling to improve osseointegration by examining the calcium phosphate (Ca-P) crystal growth behavior on the poled and non-poled BTO surfaces in simulated body fluids (SBF). The BTO samples were sintered at 1350℃ for 2 h in air, producing an average grain size of 7 ㎛, which were confirmed by SEM observation. The sintered BTO samples were then polarized (Ep=5 kV/cm) from 160℃ to 25℃ in a Si oil bath for 2 h. The poled and non-poled BTO samples were immersed in 1.5 SBF for 15 days, or 30 days at 37℃. After the immersion period, the morphological and compositional changes of the surface of the immersed BTO specimens were investigated using a field emission scanning electron microscope (FE-SEM) and an energy dispersive X-ray spectrometer (EDX). Qualitative analysis was then performed using fourier transform infrared (FTIR) analysis. Weak and coarse Ca-P crystals had grown on the surface of the non poled BTO, while a marked difference in the Ca-P forming pattern was visible for the poled BTO, showing the negatively charged surface induces a Ca-P layer more easily. We assumed that rapidly adsorbed cations (Ca2+ ions) on the negatively charged surface at the initial stage acted as nuclei for the formation of Ca-P crystals, while no nuclei would be available on the positively charged surface, due to the fact that sodium chloride (NaCl) crystals were formed owing to anion adsorption (Cl ions). In summary, these results demonstrate that poling the ferroelectric BTO surface negatively the possibility of implant osseointegration.
Seog Geun Kang,Zhenxing Chen,Ju Yeong Kim,Jin Sub Bae,Jong-Soo Lim IEEE 2011 IEEE transactions on signal processing Vol.59 No.12
<P>A simple and straightforward method of constructing higher-level three-dimensional (3-D) signal constellations for a reliable digital communication system is proposed in this paper. The new method expands basic 8-ary constellation into 3-D signal space systematically so that it produces lattice configurations. We also derive accurate closed-form symbol error probability (SEP) of cross-lattice constellations in additive white Gaussian noise (AWGN). It is verified that the theoretical SEPs are almost the same as simulation results. Minimum Euclidean distance (MED) of the higher-level 3-D constellations is increased at least 49% in comparison with quadrature amplitude modulation (QAM). When the number of symbols is 256, the 3-D constellation has around 105% longer MED than the 2-D QAM. Due to increase in MED, the 3-D constellations have much improved error performance compared to the QAM configurations. It is, therefore, considered that the higher-level 3-D constellations are appropriate for high-quality digital communications.</P>
( Soo Yeong Park ),( Hee Kyoung Lim ),( Seog Jae Lee ),( Somi Kim Cho ),( Sang Gyu Park ),( Moon Jae Cho ) 한국응용생명화학회 2011 Applied Biological Chemistry (Appl Biol Chem) Vol.54 No.5
Red variants of S. japonicus show unique ecological characteristics and are indigenous to Jeju Island in South Korea. Various biological activities of red sea cucumber extracts (RSCEs) were evaluated. In comparison with positive controls, anti-oxidant activity of RSCEs was very low. In HL-60 and HT-29 cells, chloroform and ethyl acetate (EtOAc) fractions showed higher than 80 and 60% growth inhibition, respectively. Nuclear condensation and increased pro-apoptotic signaling revealed that RSCEs triggered apoptosis. EtOAc fractions also showed strong anti-inflammatory effects at sub-lethal concentrations in lipolysaccharide-stimulated RAW264.7 cells and suppressed more than 90% of nitric oxide (NO) and prostaglandin 2 productions at 50 μg/mL by inhibiting inducible NO synthase and cydooxygenase-2. Water-soluble fractions showed good antibacterial effects against Staphylococcus aureus and Staphylococcus epidermidis.
Park, Soo-Yeong,Lim, Hee-Kyoung,Lee, Seog-Jae,Kimcho, So-Mi,Park, Sang-Gyu,Cho, Moon-Jae The Korean Society for Applied Biological Chemistr 2011 Applied Biological Chemistry (Appl Biol Chem) Vol.54 No.5
Red variants of S. japonicus show unique ecological characteristics and are indigenous to Jeju Island in South Korea. Various biological activities of red sea cucumber extracts (RSCEs) were evaluated. In comparison with positive controls, anti-oxidant activity of RSCEs was very low. In HL-60 and HT-29 cells, chloroform and ethyl acetate (EtOAc) fractions showed higher than 80 and 60% growth inhibition, respectively. Nuclear condensation and increased pro-apoptotic signaling revealed that RSCEs triggered apoptosis. EtOAc fractions also showed strong anti-inflammatory effects at sub-lethal concentrations in lipolysaccharide-stimulated RAW264.7 cells and suppressed more than 90% of nitric oxide (NO) and prostaglandin 2 productions at 50 ${\mu}g$/mL by inhibiting inducible NO synthase and cydooxygenase-2. Water-soluble fractions showed good antibacterial effects against Staphylococcus aureus and Staphylococcus epidermidis.
심포지움,특별강연 및 일반연제 발표 : 신증후군환자에 대한 사이크로스포린의 유효성 및 안전성 평가를 위한 16주 공개 다기관 임상시험 및 재발 평가를 위한 장기간 연구결과
신석균 ( Sin Seog Gyun ),이호영 ( Lee Ho Yeong ),노현정 ( No Hyeon Jeong ),노현진 ( No Hyeon Jin ),김흥수 ( Kim Heung Su ),신규태 ( Sin Gyu Tae ),김도헌 ( Kim Do Heon ),김용림 ( Kim Yong Lim ),조동규 ( Jo Dong Gyu ),홍성표 ( Hong 대한신장학회 2000 춘계학술대회 초록집 Vol.19 No.2