Calcium phosphate 결정 성장 최적화를 위한 Ti 표면의 BaTiO_3 박막 형성에 관한 연구

조진우,양홍서,박영준,황규석,송종은,이용렬 전남대학교 치과대학 2001 구강과학 Vol.13 No.2

This study was purposed to establish an optimized manufacturing process for a negatively charged ferroelectric thin flim on titanium substrate in order to develop a new implant system having the mechanical strength and bone forming ability. Ferroelectric materials show an alignment of positive and negative charges by poling treatment. Based on this property, this study was performed with the assumption that the Ca^2+ ions would be easily attracted on negatively charged surface and the attracted cation might behave as nuclei for bone-like crystal grownth in biological solutions. In order to have an osteoinducibility by the ferroelectric thin film coating, continuous and flawless crystalline thin film should be formed with ferroelectricity, and finally should be adequately poling treated. In this study, BaTiO_3 (BTO) was selected as a ferroelectric material. Before thin film coating process, most favorable poling condition was investiged with the evaluation of the difference in calcium phosphate (Ca-P) formation in simulated body fluid (SBF). Moreover, the parameters to form an optimum thin film were studied. Dense bulk BTO disks were fabricate using cold isostatic pressing(CIP) and sintered in air at 1300℃ for 2 hours. Sintered BTO disk was polished, and he crystallinity, microstructure, and ferroelectric characteristics were evaluated using an X-ray diffraction analysis (XRD), a field emission scanning electron microscope (FE-SEM), and an Impedance analyzer. To find the optimum poling condition for the calcium phosphate crystal formation, sintered bulk BTO specimens were treated with either of following poling conditions; 1) room temperature poling treatment [ polarizing field (Ep) = 25kV/cm, at 25℃ for 2 hours], 2) under Tc medium-temperaturepoling treatment (Ep=20kV/cm, from 85˚C to 25˚C for 2 hour), and 3) above Tc high-temperature poling were immesed in simulated body fluid (SBF) for 30 days, and the formation of calcium phosphate (Ca-P) layer n the surface was evaluated. The crystallinity, microstructure, and ferroelectric characteristic of BTO thin film were evaluated withthe variation of final heat treatment. It was performed after establishing the starting substance-solvent mixing ratio, coating times, and pre-heating temperature optimal to form continuous and flawless BTO thin film adequate for having ferroelectricity. Perparation of BTO thin film was made by dipping-pyrolysis technique using metal naphthenates as starting substances. BTO thin films was spin-coated on Ti substrate by dipping-pyrolysis technique using sol obtained by mixing Ba-naphthenate and Ti-naphthenate as starting substances. Pre-firing temperature of BTO thin film was performed at 450℃ because organic-solvent ws completely volatilized without any crystal growth, and the final heat treatment was performed at 600, 700 or 800℃, respectively. The results are as follows; 1. BTO disk sintered at 1300℃ for 2 hours showed average grain size of about 1㎛ and the relative dielectric constant at 1㎑ was abut 3000∼3500. 2. After immersing the sintered bulk BTO poled at respective conditions in SBF for 30 days, Ca-P layers were present on the negatively charged surfaces. In contrary, positively charged Bto surface did not show any noticeable charge of the surface microstructure after SBF immersion. 3. In he case of poling condition 1 and 2 treated with below Tc, Ca/P ratio showed a relatively low value of 1,.2∼1.5. While, in the case of poling condition 3 treated with above Tc, Ca/P ratio was 1.5∼1.67, which is similar to that of biological apatite. This phenomenon demonstrates that poling the BTO above the temperature of Tc is preferable for the Ca-P formation. 4. For thin film BTO coastin, the starting substance was prepared by an equimolar mixing of the Ba and Ti-naphthenate. Dilution of the starting substance with toluene was most appropriate at sol : toluene ratio of 5.2:4.8 Too thin sol produced porosity in film, and too thick sol resulted cracks in the film. By repeating the coating and pre-firing procedure 15 times, homogeneous film of 0.5㎛ thickness could be fabricated, and perfomed well during the poling treatment without breakdown. 5. The heat-treatmen of the BTO thin film at 700℃ produced a homogeneous crystalline structure without heterogeneous TiO2 formation. The BTO thin film heat-treated at 600℃ showed non-crystallinity and no ferroelectricity. Treatment at 800℃ produced heterogeneous TiO2 phase in the film, which is unfavorabe for having ferroelectricity by the distortion of the perovskite structure. The relative dielectic constant at 1 ㎑ was 152 and 112 by heat-treatment at 700 and 800℃, respectively. In summary, these results demonstrated that poling the ferroelectric B_aT_iO_3 surface negatively is effective for the formation of Ca-P layer in simulated body fluids. Poling condition at a temperature cooling from above Tc down to room temperature is most effective. By optimizing the method of BTO thin film coating on metal substrate for the formation of Ca-P layer, the data of this study might be applied for the manufacture of new bioactive implant system.

김치유래 젖산균의 균체지방산 분석을 이용한 분류학적 연구

이정숙,정민철,김우식,이근철,김홍중,박찬선,이헌주,주윤정,이근종,안종석,박완,박용하,민태익 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 1996 한국미생물·생명공학회지 Vol.24 No.2

표준균주를 포함한 230여개의 김치유래 젖산균에 대한 균체지방산(FAMEs)을 분석하였다. FAMEs profiles는 Euclidian Distance 17.5에 의해 7개의 Major Cluster와 1개의 Single Cluster로 나뉘어졌다. 이중 A, B, C 및 Cluster는 Leuconostoc속으로 분석되어졌고, F는 Lactobacillus속으로 분석되어졌다. 그리고 E와 G cluster는 두개의 Genus가 혼재되어 나타났으며 보충적인 연구가 필요하다. 앞으로 김치유래 젖산균의 균체지방산 분석결과를 기반으로 한 데이타베이스에 95가지 탄소원을 이용하는 수치분류학적 접근방법 및 Pyrolysis Mass Spectrometry 등의 화학적 분석 방법과 분자친화적 연구를 통한 종합적 분류정보 체계가 갖추어지면 젖산균의 신속, 정확한 동정 및 연구에 활발히 이용되어질 것이다. Two hundreds and thirty lactic acid bacteria, mostly isolated from Kimchi, including type strains were sued for analysis of cellular fatty acids. The 230 test strains were recoverd in 7 major and 1 single clusters defined a Euclidian distance of 17.5. These aggregate taxa were equivalent to the genus Leuconostoc (aggregate group A, B, C and D), and the genera Leuconostoc and Lactobacillus (aggregate group G). It is concluded as evident that FAMEs (Fatty Acid Methyl Esters) profile of cell can be used as a criterion in classification of lactic acid bacterial from kimchi. Additional comparative taxonomic studies need to be carried out on well chosen representative strains to determine the most appropriate methods of value.

CD34+ 조혈 모세포 이식 2례

김정아,정현식,김원석,윤성수,이홍기,박찬형,박성규,김동욱,이종욱,한치화,민우성,김춘추,김동집 대한조혈모세포이식학회 1996 대한조혈모세포이식학회지 Vol.1 No.1

Background: In most solid tumors, the CD34 antigen has not been detected, so positive selection of CD34+ cells may reduce tumor cell contamination and the CD34+ cells are capable of reconstituting hematopoiesis. We tried CD34+ cell transplantation in two patients. Method: CD34+ cells from chemotherapy + G-CSF mobilized PBPCs or bone marrow were positively selected with an avidin-biotin immunoadsorption column (CEPRATE SC system). Case 1. One course of chemotherapy using cyclophosphamide(200㎎/㎡) and etoposide (4.2g/㎡), combined with G-CSF(5㎍/㎏) S.C. was used in a relapsed lymphoma patient. This patient responded to the induction chemotherapy. CD34+ cells from harvested bone marrow were selected by the CellPro immunoadsorption column. The total number of mononuclear cells loaded onto the CellPro was 2.4×10^(8)/㎏, with 1.1% CD34+ cells. After column separation, the total number of positively selected cells was 5.16×10^(6)/㎏. The number of CFU-GM was 76.8×10⁴/㎏. This patient was treated with melphalan (140㎎/㎡) and TBI (1200cGy) and the positively selected CD34+ cells were infused. The time to neutrophil recovery greater than 0.5×10^(9)/L was 19 days and the time to platelet recovery greater than 50×10^(9)/L was 21 days. Case 2. Two courses of mobilizing chemotherapy were given 4 weeks apart using taxol(210㎎/m2) and adriamycin(60㎎/m2), combined with G-CSF(5㎍/㎏) S.C. in a breast cancer patients with 7 axillary node metastasis. CD34+ cells from each single leukapheresis product were selected by the CellPro immunoadsorption column. In the first collection, the total number of nucleated cells was 4.4×10^(8)/kg, with 0.42% CD34+ cells. In the second collection, the total number of nucleated cell was 2.8× 10^(8)/㎏ with 0.43% CD34+ cells. After colum separation, the total numbers of collected cells were 4.0×106/kg and 4.8×10^(6)/kg, the total number of CD34+ cells were 1.2×10^(6)/㎏ and 0.82×10^(6)/㎏. Colonogenic assays of positively selected CD34+ cells gave rise to myeloid erythroid, and multilineage colonies, with a median of 190 CFU-GM, 190 BFU-E, and 164 CFU-GEMM per 1×10³ adsorbed cells, respectively. High-dose chemotherapy with cumulative doses of 40mg/㎡ mitoxantrone, 750mg/㎡ thioptepa, and 1000mg/㎡ carboplatin was administered. Positively selected CD34+ cells were rapidly infused 24 hours after the end of high-dose chemotherapy. The time to neutrophil recovery greater than 0.5×10^(9)/L was 16 days and the time to platelet recovery greater than 50×10^(9)/L was 20 days.

Which is the most accurate parameter to estimate the pulmonary wedge pressure in critically ill patients?

Woo Hyung Bae,June Hong Kim,Jun Hyuk Oh,Dong Won Lee,Sung Gook Song,Jeong Su Kim,Hyeon Gook Lee,Woo Seog Ko,Yong Hyun Park,Sang Gwon Lee,Kook Jin Chun,Taek Jong Hong,Yung Woo Shin 대한내과학회 2004 대한내과학회 추계학술대회 Vol.2004 No.1

대용량 유도전동기 사고사례 고찰

채지석(Ji Seog Chae),이은춘(Eun-Chun Lee),박종순(Jong Soon Park),김재학(Jae Hak Kim),이종석(Jong Seog Lee),최영규(Yong Kyu Choi),이헌우(Heon Woo Lee) 한국조명·전기설비학회 2014 한국조명·전기설비학회 학술대회논문집 Vol.2014 No.5

Development of Alkali Metal Thermal-to-Electric Converter Unit Cells Using Mo/TiN Electrode

Seog, Seung-won,Choi, Hyun-Jong,Kim, Sun-Dong,Lee, Wook-Hyun,Woo, Sang-Kuk,Han, Moon-Hee The Korean Ceramic Society 2017 한국세라믹학회지 Vol.54 No.3

Molybdenum (Mo), an electrode material of alkali metal thermal-to-electric converters (AMTEC), facilitates grain growth behavior and forms Mo-Na-O compounds at high operating temperatures, resulting in reduced performance and shortened lifetime of the cell. Mo/TiN composite materials have been developed to provide a solution for such issues. Mo is a metal that possesses excellent electrical properties, and TiN is a ceramic compound with high-temperature durability and catalytic activity. In this study, a dip-coating process with an organic solvent-based slurry was used as an optimal coating method to achieve homogeneity and stability of the electrodes. Cell performance was evaluated under various conditions such as the number of coatings, ranging from 1 to 3 times, and heat treatment temperatures of $800-1100^{\circ}C$. The results confirmed that the cell yielded a maximum power of 9.99 W for the sample coated 3 times and heat-treated at $900^{\circ}C$.

Step-wise Anion-Exchange in Layered Double Hydroxide Using Solvothermal Treatment

Jong Hyeon Lee,Seog Woo Rhee,정덕영 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.2

Synthetic layered double hydroxides (LDHs), [Mg4Al2(OH)12]CO3ánH2O, were prepared in the submicron size of plate-like polycrystals. Anion-exchange reactions with various linear dicarboxylic acids were performed to produce LDH/organic hybrid materials by solvothermal treatment in toluene. X-ray powder diffraction spectra for the products indicated that the interlayer spacings of LDHs remarkably changed, up to 20 Å when 1,10-decanedicarboxylic acid anions were intercalated as an organic guest. Dicarboxylates-LDHs samples could be also re-exchanged consecutively with other dicarboxylic acids or carbonate without serious destruction of layer structure under the scanning electron microscopic observation

Isolation of hyperthermal stress responsive genes in soft coral (Scleronephthya gracillimum)

Woo, Seon-Ock,Jeon, Hye-Young,Lee, Jong-Rak,Song, Jun-Im,Park, Hong-Seog,Yum, Seung-Shic The Korean Society of Toxicogenomics and Toxicopro 2010 Molecular & cellular toxicology Vol.6 No.4

The extensive isolation of genes responsive to hyperthermal stress conditions in soft coral (Scleronephthya gracillimum) is described. Soft coral colonies were exposed to high seawater temperature conditions. Gene candidates whose transcript levels changed in response to hyperthermal conditions were identified by differential display polymerase chain reaction (DD-PCR). Twenty-four types of candidate genes were identified, 18 of which were upregulated in expression and 6 of which were downregulated. The genes were found to function in post-translational modification, protein turnover and chaperones (O); translation, ribosomal structure and biogenesis (J); signal transduction mechanisms (T); defense mechanisms (V); inorganic ion transport and metabolism (P); energy production and conversion (C); cytoskeleton (Z); cell cycle control, cell division and chromosome partitioning (D); lipid transport and metabolism (I); chromatin structure and dynamics (B); transcription (K); replication, recombination and repair (L); secondary metabolites biosynthesis, transport and catabolism (Q); extracellular structures (W); general function prediction (R); and finally, unknown function (S) based on KOG classification. Among these candidates, their expressional changes were confirmed by real-time quantitative PCR (qRT-PCR). These 24 isolated gene candidates were differentially expressed and therefore have great potential as molecular biomarkers for the identification of environmental stressors.

Classification of Isolates Originating from Kimchi Using Carbon - source Utilization Patterns

Jong Sook Lee,Chang Ouk Chun,Min Chul Jung,Woo Sik Kim,Hong Joong Kim,Martin Hector,Sam Bong Kim,Chan Sun Park,Jong Seog Ahn,Yong Ha Park,Tae Ick Mheen 한국미생물생명공학회 1997 Journal of microbiology and biotechnology Vol.7 No.1

Development of mathematical model on regionalization using records of livestock related vehicles for control strategy of highly pathogenic avian influenza

Jong hyun Seo,Hyuk Park,Kwang Hee Han,Woo seog Jeong,Ha chung Yoon,Ki Hyun Cho,Chung Sik Jung,Yong Myung Kang,Hong Sik Park,Son Il Pak,Hun seok Kang 한국예방수의학회 2017 예방수의학회지 Vol.41 No.4

In this paper, a mathematical model of regionalization based on graph theory to investigate the patterns induced by movements of livestock vehicles in cities under outbreaks of highly pathogenic avian influenza (HPAI) is proposed. We then compare the results of simulation from the regionalization model to actual HPAI outbreaks in 2016/2017 to evaluate the validity of the model. Specifically, we (1) configured a complex network structure with analytic tools and properties in graph theory to abstract the paths among farms and livestock facilities; (2) employed statistical methods to estimate the possibility of propagation between two clusters; (3) applied the developed method to an actual HPAI outbreak in Korea in 2016 and conducted a simulation to determine if the proposed modeling for regionalization is an effective prediction measure. The clustered regions proposed by the simulation correctly reflected the regional clustering of actual cases, while simultaneously contain the cities exposed to potential damage when separated. Based on these findings, we conclude that our proposed regionalization model is suitable for making policy judgments to establish a preemptive biosecurity system.