• Journal of Microbiology and Biotechnology
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• 제28권3호
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• pp.439-447
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• 2018

The aromatic compound p-hydroxybenzoate (PHBA) is an important material with multiple applications, including as a building block of liquid crystal polymers in chemical industries. The cytochrome P450 (CYP) enzymes are beneficial monooxygenases for the synthesis of chemicals, and CYP53A15 from fungus Cochliobolus lunatus is capable of executing the hydroxylation from benzoate to PHBA. Here, we constructed a system for the bioconversion of benzoate to PHBA in Escherichia coli cells coexpressing CYP53A15 and human NADPH-P450 oxidoreductase (CPR) genes as a redox partner. For suitable coexpression of CYP53A15 and CPR, we originally constructed five plasmids in which we replaced the N-terminal transmembrane region of CYP53A15 with a portion of the N-terminus of various mammalian P450s. PHBA productivity was the greatest when CYP53A15 expression was induced at $20^{\circ}C$ in $2{\times}YT$ medium in host E. coli strain ${\Delta}gcvR$ transformed with an N-terminal transmembrane region of rabbit CYP2C3. By optimizing each reaction condition (reaction temperature, substrate concentration, reaction time, and E. coli cell concentration), we achieved 90% whole-cell conversion of benzoate. Our data demonstrate that the described novel E. coli bioconversion system is a more efficient tool for PHBA production from benzoate than the previously described yeast system.

• 대한기계학회논문집B
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• 제20권10호
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• pp.3334-3343
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• 1996

A quantitative flow visualization technique was developed to measure velocity and temperature fields simultaneously in a two-dimensional cross section of thermo-fluid flows. Thermochromic liquid crystal(TLC) particles are used as temperature sensor and velocity tracers. Illuminating a thermo-fluid flow with a thin sheet of white light, the reflected colors from the TLC particles in the flow were captured simultaneously by two CCD cameras; a 3-chip CCD color camera for temperature field measurement and a black and white CCD camera for velocity field measurement. Variations of temperature field were measured by using a HSI true color image processing system and TLC solution. The relationship between the hue values of TLC color image and real temperature was obtained and this calibration curve was used to measure the true temperature under the same camera and illumination condition. The velocity field was obtained by using a 2-frame PTV technique using the concept of match-probability to track true velocity vectors from two consecutive image frames. These two techniques were applied at the same time to the unsteady thermal-fluid flow in a Hele-Shaw cell to measure the temperature and velocity field simultaneously and some results are discussed.

• Toxicological Research
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• 제30권1호
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• pp.55-63
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• 2014

Objectives: The use of indium compounds, especially those of small size, for the production of semiconductors, liquid-crystal panels, etc., has increased recently. However, the role of particle size or the chemical composition of indium compounds in their toxicity and distribution in the body has not been sufficiently investigated. Therefore, the aim of this study was to examine the effects of particle size and the chemical composition of indium compounds on their toxicity and distribution. Methods: Male Sprague-Dawley rats were exposed to two different-sized indium oxides (average particle sizes under 4,000 nm [IO_4000] and 100 nm [IO_100]) and one nano-sized indium-tin oxide (ITO; average particle size less than 50 nm) by inhalation for 6 hr daily, 5 days per week, for 4 weeks at approximately $1mg/m^3$ of indium by mass concentration. Results: We observed differences in lung weights and histopathological findings, differential cell counts, and cell damage indicators in the bronchoalveolar lavage fluid between the normal control group and IO- or ITO-exposed groups. However, only ITO affected respiratory functions in exposed rats. Overall, the toxicity of ITO was much higher than that of IOs; the toxicity of IO_4000 was higher than that of IO_100. A 4-week recovery period was not sufficient to alleviate the toxic effects of IO and ITO exposure. Inhaled indium was mainly deposited in the lungs. ITO in the lungs was removed more slowly than IOs; IO_4000 was removed faster than IO_100. IOs were not distributed to other organs (i.e., the brain, liver, and spleen), whereas ITO was. Concentrations of indium in the blood and organ tissues were higher at 4 weeks after exposure. Conclusions: The effect of particle size on the toxicity of indium compounds was not clear, whereas chemical composition clearly affected toxicity; ITO showed much higher toxicity than that of IO.

• Applied Microscopy
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• 제16권2호
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• pp.1-13
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• 1986

The purpose of this study was to investigate the morphology and intercellular junctions of the odontoblast of dental pulp in the rat incisor by means of the freeze fracture electron microscopy. Twenty male Sprague-Dawley rats weighing $150{\sim}200g$ were used. After being anesthetized by an intraperitoneal injection of 0.5 ml sodium pentobarbital per kg in body weight(60 mg/ml) the animals were perfused with 2.5% glutaraldehyde-2% paraformaldehyde fixative in 0.1 M cacodylate buffer, pH 7.2 through the ascending aorta for one hour. The incisors were carefully extracted from the jaws and demineralized by suspending them in 0.1 M EDTA in 3% glutaraldehyde (pH 7.2) for two weeks. After demineralization, the specimens were obtained from the portion divided into five equal parts. For freeze-fracture replication, demineralized tissues were infiltrated for several hours with 10%, 25% glycerol in 0.1M cacodylate buffer as a cryoprotectant and then frozen in liquid Freon 22 and stored in liquid nitrogen. Fracturing and replication were done in Balzers BAF 400D high-vacuum freeze-fracture apparatus at $-120^{\circ}C$ under routine $5X10^{-7}$ Torr vacuum. The tissue was immediately replicated with platinum unidirectionally at $45^{\circ}$ angle and reinforced with carbon at $90^{\circ}$ angle unidirectionally or by using a rotary stage. The replication process was monitored by a quartz-crystal device. The replicas were immersed in 100% methanol overnight. The tissue was then digested from the replica by clorox (laundry bleach), placed into 5% EDTA, and washed repeatedly with distilled water. The replicas were picked up on 0.3% formvar-coated 75 mesh grids and examined in the JEOL 100B electron microscope. The results were as follows; 1. Both in thin sections and freeze-fracture replicas, three types of intercellular junctions were recognizable in the plasma membrane of odontoblast: gap junction, tight junction and desmosome-like junction. 2. The nuclear pores were evenly distributed over the nuclear envelope. The pore complex formed a ring about 70 nm in diameter. 3. Gap junctions were found between odontoblasts as well as odontoblasts and neighbouring pulp cells (fibroblast, subodontoblastic cell process, nerve-like fibre). Gap junctions, which were round, ellipsoid and pear-shaped and 600 nm in diameter, were observed in the odontoblast. 4. Numerous round and ellipsoid gap junctions could be frequently seen on the plasma membranes in cell body and apical part of the odontoblasts. On the P face, the junctions were recognized as a cluster of closely packed particles, measuring about 9 nm in diameter, and on the E face, the junctions were recognized as a shallow grooves.

• Journal of Mechanical Science and Technology
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• 제18권9호
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• pp.1680-1688
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• 2004

The information indicating device plays an important part in the information times. Recently, the classical CRT (Cathod Ray Tube) display is getting transferred to the LCD (Liquid Crystal Display) one which is a kind of the FPDs (Flat Panel Displays). The OLED (Organic Light Emitting Diodes) display of the FPDs has many advantages for the low power consumption, the luminescence in itself, the light weight, the thin thickness, the wide view angle, the fast response and so on as compared with the LCD one. The OLED has lately attracted considerable attention as the next generation device for the information indicators. And also it has already been applied for the outside panel of a mobile phone, and its demand will be gradually increased in the various fields. It is manufactured by the vapor deposition method in the vacuum state, and the uniformity of thin film on the substrate depends on the temperature distribution in the point-cell source. This paper describes the basic concepts that are obtained to design the point-cell source using the computational temperature analysis. The grids are generated using the module of AUTOHEXA in the ICEM CFD program and the temperature distributions are numerically obtained using the STAR-CD program. The temperature profiles are calculated for four cases, i.e., the charge rate for the source in the crucible, the ratio of diameter to height of the crucible, the ratio of interval to height of the heating bands, and the geometry modification for the basic crucible. As a result, the blowout phenomenon can be shown when the charge rate for the source increases. The temperature variation in the radial direction is decreased as the ratio of diameter to height is decreased and it is suggested that the thin film thickness can be uniformed. In case of using one heating band, the blowout can be shown as the higher temperature distribution in the center part of the source, and the clogging can appear in the top end of the crucible in the lower temperature. The phenomena of both the blowout and the clogging in the modified crucible with the nozzle-diffuser can be prevented because the temperature in the upper part of the crucible is higher than that of other parts and the temperature variation in the radial direction becomes small.

• 한국전기전자재료학회논문지
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• 제28권7호
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• pp.439-445
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• 2015

We established the emulsion method using membrane filter with precise control of LC droplet distribution in PDLC. PDLC cells with various LC droplet size distributions such as single droplet sizes of $1.0{\mu}m$, $1.9{\mu}m$ and $3.5{\mu}m$, the mixture of two different LC droplet sizes and the mixture of three different LC droplet sizes were fabricated and the electro-optical properties of the emulsion type PDLC cells with various droplet size distribution were investigated. In the appropriate droplet size range, the PDLCs with the single droplet sizes distributions have good electro optical properties than those with the mixture of three different LC droplet sizes. In addition, the PDLC cells with the mixture of two different LC droplet sizes have the better electro optical properties than those with single droplet sizes distribution. The PDLC cell with dual droplet size distribution of $1.0+1.9{\mu}m$ shown the best electro optical properties than the PDLC cells with other size distributions. This method enabled us to find the proper LC droplet size distribution for achieving both high transmittance and contrast ratio.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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• pp.57-60
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• 2003

Electro-Optical (EO) performances for the ion beam (IB) aligned twisted-nematic (TN)-liquid crystal display (LCD) with ion beam exposure on the new of diamond like carbon (DLC) thin film surface were investigated. Voltage-transmittance (V-T) curve and response time without backflow bounce in the ion beam aligned TN-LCD with ion beam exposure for 0.5 and 1min on the DLC thin film was observed. Also. the fast response time of ion beam aligned TN-LCD with ion beam exposure for 1min on the DLC thin film surface can be achieved. The residual DC voltage of the ion beam aligned TN-LCD on the DLC thin film surface was almost the same as that of the rubbing aligned TN-LCD on the polyimide(PI) surface.

• Journal of Microbiology and Biotechnology
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• 제12권4호
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• pp.544-552
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• 2002

Several microorganisms from rat and human feces and lumen fluid of cows were screened for their ability to decolorize the synthetic dyes. Consequently, a novel dye-degrading strain AB&J was isolated. Taxonomic identification including 165 rDNA sequencing and phylogenetic analysis indicated that the isolate had 99.9% homology in its 165 rDNA base sequence with Clostridium perfringens. After 27 h Incubation with the strain, brilliant blue R, bromophenol blue, crystal violet, malachite green, methyl green, and methyl orange were decolorized by about 69.3%, 97.7%, 96.3%, 97.9%, 75.1%, and 97.2%, respectively. The triphenlmethane dye, bromophenol blue, was decolorized extensively by growing Clostridium perfringens AB&J cells in liquid cultures under anaerobic condition, although their growth was strongly inhibited in the initial stage of incubation. This group of dyes is toxic, depending on the concentration used. The dye was significantly decolorized at a relatively lower concentration of below 50 $\mu g \;ml^{-1}$, however, the growth of the cells was mostly suppressed at a dye concentration of 100 $\mu g \;ml^{-1}$. The decolorization activity in cell-free extracts was much higher in cytoplasm than in periplasm and cytoplasmic membrane. Therefore, the enzyme related uptake of bromophenol blue seemed to be localized in cytoplasm. The optimal pH and temperature of bromophenol blue uptake fur decolorization activities were 7.0 and 4$0^{\circ}C$, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.430-430
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• 2007

In this study, the nematic liquid crystal (NLC) alignment effects treated on the ZnO thin film layers using ion beam irradiation were successfully studied for the first time. The ZnO thin films were deposited on indium-tin-oxide (ITO) coated glass substrates by rf-sputter and The ZnO thin films were deposited at the three kinds of rf power. The used DuoPIGatron type ion beam system, which can be advantageous in a large area with high density plasma generation. The ion beam parameters were as follows: energy of 1800 eV, exposure time of 1 min and ion beam current of $4\;mA/cm^2$ at exposure angles of $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$. The homogeneous and homeotropic LC aligning capabilities treated on the ZnO thin film surface with ion beam exposure of $45^{\circ}$ for 1 min can be achieved. The low pretilt angle for a NLC treated on the ZnO thin film surface with ion beam irradiation for all incident angles was measured. The good LC alignment treated on the ZnO thin film with ion beam exposure at rf power of 150 W can be measure. For identifying surfaces topography of the ZnO thin films, atomic force microscopy (AFM) was introduced. After ion beam irradiation, test samples were fabricated in an anti-parallel configuration with a cell gap of $60{\mu}m$.

• 한국광물학회지
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• 제5권2호
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• pp.109-121
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• 1992

본 연구는 토파즈의 인공착색 처리 방법을 설정하기 위하여 브라질, 중국, 인도, 나이지리아, 스리랑카 등 5개국에서 산출된 토파즈를 대상으로, 전자현미분석(EPMA), 중성자활성분석(NAA), X선 회절분석, 라만 분광분석, 주사현미경(SEM), 부식시험, 굴절률측정, 비중측정, 유체 포유물 관찰 등의 실험을 실시하여 광물학적, 화학적 특성에 관한 연구를 수행하였다. 연구 결과 토파즈는 산지에 따라 화학적, 구조적 및 물리적 특성의 차이를 나타내었으며 특히, F와 OH 고용체 함량의 차이는 물리적, 구조적 특성과 밀접한 관련성이 있음이 확인되었다. F에 대한 OH로 치환정도가 가장 높은 인도산 토파즈는 굴절률, 단위포상수 b, 단위포 체적 및 ${\Delta}021$값이 가장 크고, 비중값은 가장 작으며 스리랑카산, 중국산, 브라질산, 나이지리아산순으로 F에 대한 OH로 치환 정도가 낮다. F에 대한 OH로 치환정도가 가장 낮은 나이지리아산 토파즈는 굴절률, 단위포상수 b, 단위포 체적 및 ${\Delta}021$값이 가장 작고, 비중값은 가장 크다. 토파즈내에 함유되는 미량원소종은 Na, Fe, Br, Co, Ce, La, Sm, Th, Au, Sc, Cr 등이며 이러한 미량원소의 정성정량적 특성은 물리적 특성에는 거의 영향을 미치지 않았다. 라만 분광분석 결과 토파즈의 피크는 산지에 따라 강도의 차이를 나타내었으며 브라질산과 인도산은 455∼458($cm^{-1}$)근처의 피크, 중국산은 282∼284($cm^{-1}$) 근처의 피크가 나타나지 않았다. 산지에 따른 결정구조결함 특성은 주로 point-bottom pit의 negative crystal defect(인도산, 나이지리아산)와 curl-bottom pit의 net work defect(브라질산, 중국산)로 구분되며, 결정내에 발달하는 미세한 균열을 따라 형성된 선결함 양상(linear defect)을 보여준다. 유체 포유물의 특징은 브라질산이 액상 $CO_2$를 가지는 III형이고, 중국산에는 유체 포유물이 거의 관찰되지 않으며 단지 $10{\mu}m$이하의 매우 작은 크기인 초생포유물의 극소량 존재한다. 인도산은 기체가 풍부한 II형이고, 나이지리아산은 암염, 실바이트 등의 고체 포유물을 함유하는 IV형이며 스리랑카산은 거의 대부분의 유체 포유물이 2차 생성의 I형이 주로 형성되어 있다. 본 연구의 결과는 광물학적 특성의 차이를 갖는 산지별 토파즈의 인공착색을 위한 처리 방법을 설정하는 유용한 기초 자료로 이용될 수 있을 것이다.