• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.9.2-9.2
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• 2011

Ultrathin polyelectrolyte (PE) multilayer films prepared by the versatile layer-by layer (LbL) assembly method have been utilized for the preparation of light-emitting diodes, electrochromic, membrane, and drug delivery system, as well as for selective area patterning and particle surface modification because the various materials with specific properties can be inserted into the film with nano-level thickness irrespective of the size or the shape of substrate. Since the introduction of the LbL technique in 1991 by Decher and Hong, various hydrophilic materials can be inserted within LbL films through complementary interactions (i.e., electrostatic, hydrogen-bonding or covalent interaction). In this study, it is demonstrated that LbL SA multilayer films based on nucleophilic substitution reaction can allow the preparation of the highly efficient magnetic and/or optical films and nonvolatile memory devices.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.373-380
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• 2020

This study was carried out to convert the hydrophobic characteristics of PVDF to hydrophilic. Poly(-vinylidene fluorine) (PVDF) was grafted by electron beam irradiation and sulfonated. The grafting degree of modified PVDF increased with the monomer concentration, but not the conversion degree. From the results of FTIR and XPS, it was shown that the amount of converted sulfur increased with the grafting degree. The radiation-induced graft polymerization led to decrease fluorine from 35.7% to 21.3%. Meanwhile, the oxygen and sulfur content increased up to 8.1% and 3.2%. The pore size of modified membranes was shrunken and the roughness sharply decreased after irradiation. The ion exchange capacity and contact angle were investigated to show the characteristics of PVDF. The enhanced ion exchange capacity and lower contact angle of modified PVDF showed that the hydrophilicity played a role in determining membrane fouling. Electron beam irradiation successfully modified the hydrophobic characteristics of PVDF to hydrophilic.

• 전기화학회지
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• 제11권4호
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• pp.256-261
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• 2008

본 연구에서는 나피온 막을 통한 메탄올 투과도를 감소시키기 위하여 양전하를 띠는 polyaniline(PANi)와 음전하를 갖는 sulfonated Poly(ether sulfone)(SPES)으로부터 다층 자기조립 박막법으로 나피온 막의 표면을 개질하였다. PANi과 SPES는 열적 화학적으로 안정하며 매우 강직한 특성을 띄고 있어, 나피온 막 표면에 다층 자기조립 박막 형성시 메탄올 투과도 감소 및 치수 안정성의 향상을 기대할 수 있다. 자외선-가시광선 흡광분석에 의하여 PANi와 SPES의 다층박막의 형성이 균일하게 이루어짐을 확인 하였다. TEM 분석을 통하여 다층 자기조립 박막의 bilayer당 두께가 약 10 nm 정도임을 확인 하였다. 개질된 나피온 막은 순수한 나피온 막에 비하여 15%의 이온전도도 감소가 일어났지만 67%의 높은 메탄올 투과도 감소를 나타내어 2.5배 높은 선택도를 보였다. 5 M 메탄올을 연료로 사용한 연료전지 성능시험에서 개질된 나피온 막은 순수한 나피온 막에 비해 최대 전력 밀도가 $30^{\circ}C$에서는 2.4배 증가, $60^{\circ}C$에서는 1.4배 향상을 나타내었다.

• Membrane and Water Treatment
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• 제9권5호
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• pp.301-307
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• 2018

In this research work, synthesis of sugarcane bagasse/zinc aluminium biocomposite and apple peel/zinc aluminium biocomposite and their application for removal of Reactive Red-241 and Acid Orange-7, respectively, was studied using various parameters. At pH 2 the sorption was the highest for both dyes. The trend showed that the dye sorption declined by decreasing the biocomposite dose and enhanced by increasing the dye concentration and temperature. Equilibrium was achieved at 60 minutes for Reactive Red-241 onto sugarcane bagasse/zinc aluminium biocomposite and 90 minutes for Acid Orange-7 onto apple peel/zinc aluminium biocomposite.The research data was good fitted to pseudo-2nd-order kinetic model and Langmuir isotherm. FT-IR analysis was used to confirm the biosorption of the selected dyes at the surface of biosorbent through various binding sites. Surface morphology modification of both biocomposites before and after biosorption was inspected through SEM. Crystallinity of biocomposite was examined through XRD analysis. It was implied that sugarcane bagasse/ zinc aluminium biocomposite and apple peel/ zinc aluminium biocomposite are good adsorbents for dyes elimination from aqueous solutions.

• 한국수정란이식학회지
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• 제28권3호
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• pp.289-295
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• 2013

Xenotransplantation of pig organs into primates results in fatal damage, referred as hyperacute rejection (HAR), and acute humoral xenograft rejection (AHXR), to the organ graft mediated by antibodies pre-existing and newly-producing in primates against their cognate pig antigens. Functional ablation of ${\alpha}1$,3-galactosyltransferase (Gal-T KO) of pig which is an enzyme involved in synthesis of Gala1-3Galb1-4GlcNAc-R antigen is essentially required to prevent HAR. Moreover, additional genetic modification under Gal-T KO background for enforced expression of human complement regulatory proteins which can inhibits complement activation is known to effectively imped HAR and AHXR. In this study, we constructed a membrane cofactor protein (MCP) expression cassette under control of human $EF1{\alpha}$ promoter. This cassette was inserted between homologous recombination regions corresponding to Gal-T locus. Subsequently this vector was introduced into ear skin fibroblasts of female pig by nucleofection. We were able to obtained 40 clones by neomycin selection and 4 clones among them were identified as clones targeted into Gal-T locus of MCP expression cassette by long-range PCR. Real time RT-PCR was shown to down-regulation of Gal-T expression. From these results, we demonstrated human $EF1{\alpha}$ promoter could induce efficient expression of MCP on cell surface of fibroblasts of female pig.

• 한국표면공학회지
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• 제49권3호
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• pp.286-300
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• 2016

Pd-Ag alloy membranes have attracted a great deal of attention for their use in hydrogen purification and separation due to their high theoretical permeability, infinite selectivity and chemical compatibility with hydro-carbon containing gas streams. For commercial application, Pd-based membranes for hydrogen purification and separation need not only a high perm-selectivity but also a stable long-term durability. However, it has been difficult to fabricate thin, dense Pd-Ag alloy membranes on a porous stainless steel metal support with surface pores free and a stable diffusion barrier for preventing metallic diffusion from the porous stainless steel support. In this study, thin Pd-Ag alloy membranes were prepared by advanced Pd/Ag/Pd/Ag/Pd multi-layer sputter deposition on the modified porous stainless steel support using rough polishing/$ZrO_2$ powder filling and micro-polishing surface treatment, and following Ag up-filling heat treatment. Because the modified Pd-Ag alloy membranes using rough polishing/$ZrO_2$ powder filling method demonstrate high hydrogen permeability as well as diffusion barrier efficiency, it leads to the performance improvement in hydrogen perm-selectivity. Our membranes, therefore, are expected to be applicable to industrial fields for hydrogen purification and separation owing to enhanced functionality, durability and metal support/Pd alloy film integration.

• BMB Reports
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• 제37권3호
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• pp.330-338
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• 2004

Different types of cardiotoxin (I-V and n) were isolated and purified from the venom of the Taiwan cobra (Naja naja atra). The effects of these cardiotoxins were studied on membrane-bound acetylcholinesterase, which was isolated from a sheep's brain cortex. The results showed that cardiotoxins I-III, V, and n activated the enzyme by modification of substrate inhibition, but cardiotoxin IV's reaction was different. The inhibition and activation of acetylcholinesterase were linked to the functions of the hydrophobicity index, presence of a cationic cluster, and the accessible arginine residue. Our results indicate that Cardiotoxins have neither a cationic cluster nor an arginine residue in their surface area of loop I; therefore, in contrast to fasciculin, cardiotoxins are attached by loop II to the peripheral site of the enzyme. As a result, fasciculin seems to stabilize nonfunctional conformation, but cardiotoxins seem to stabilize the functional conformation of the enzyme. Based on our experimental and theoretical findings, similar secondary and tertiary structures of cardiotoxins and fasciculin seem to have an opposite function once they interact with acetylcholinesterase.

• 한국동물학회지
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• 제32권2호
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• pp.142-152
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• 1989

CALLA 항원에 대한 단일클론 항체는 백혈병의 진단이나 치료에 대한 활용가능성을 잠재하고 있기 때문에 구미, 일본 등지에서는 이에 대한 연구가 활발하다. 이 점에 유의하여 본 연구자들은 CALLA에대한 새로운 단일클론항체 KP-22를 개발하고, 이 단일클론항체를 이용 CALLA의 분포를 여러 세포주에 대하여 조사한 결과 common ALL, Burkitt's lymphoma, T-ALL 세포주는 현저한 CALLA양성 반응을 보였으나 사람의 섬유아세포 계역을 제외한 모든 비백혈병성 암세포주 및 myelocytic leukemia 세포주들은 음성이었다. 막 단백질을 125I 방사능 표지한 후 KP-22를 이용, 면역 침전법으로 백혈병세포주와 사람의 정상 섬유아세포에서 CALLA를 정제하여 전기영동한 결과 각각 분자량이 약 95Kd 및 100Kd인 단일 band로 확인되었으나 이들의 peptide mapping 양상은 같았으므로 분자량에서의 미세한 차이는 posttranslational modification 과정에서 첨가되는 sialic acid에 기인 하는 것으로 사료된다.

• 한국정밀공학회지
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• 제24권4호
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• pp.138-146
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• 2007

Some biodegradable polymers and other materials such as hydrogels have shown the promising potential for surgical applications. Post surgical adhesion caused by the natural consequence of surgical wound healing results in repeated surgery and harmful effects. Recently, scientists have developed absorbable anti-adhesion barriers that can protect a tissue from adhesion in case they are in use; however, they are dissolved when no longer needed. Although these approaches have been attempted to fulfill the criteria for adhesion prevention, none can perfectly prevent adhesions in all situations. Overall, we developed a new method to fabricate an anti-adhesion membrane using biodegradable polymer and hydrogel. It employed a highly accurate three-dimensional positioning system with pressure-controlled syringe to deposit biopolymer solution. The pressure-activated microsyringe was equipped with fine-bore nozzles of various inner-diameters. This process allowed that inner and outer shapes could be controlled arbitrarily when it was applied to a surgical region with arbitrary shapes. In order to fulfill the properties of the ideal barriers f3r preventing postoperative adhesion, we adopted the pre-mentioned method combined with surface modification with the hydrogel coating by which anti-adhesion property was improved.

• Journal of Pharmaceutical Investigation
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• 제39권3호
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• pp.155-159
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• 2009

In vitro intestinal uptake of non-soluble polystyrene microspheres (NPMS) was visualized with and without oleic acid using a fluorescence microscopy. Fluorescent polystyrene latex microspheres with 1${\mu}$m larger size were used as models for nonspecifically absorbed nonbiodegradable particulates. The NPMS could not penetrate the enterocytes but a few NPMS could be penetrated via Peyer's patches. When the oleic acid was mixed with NPMS, the transporting efficiency of NPMS through enterocytes as well as Peyer's patches was significantly enhanced. The modification of the intestinal membrane permeability and surface feature of the NPMS in the presence of oleic acid might be a clue to the transport of NSPM although the detailed mechanism is still under investigation.