• Title/Summary/Keyword: Non-crosslinked

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Diverse patterns of bone regeneration in rabbit calvarial defects depending on the type of collagen membrane

  • Hong, Inpyo;Khalid, Alharthi Waleed;Pae, Hyung-Chul;Song, Young Woo;Cha, Jae-Kook;Lee, Jung-Seok;Paik, Jeong-Won;Choi, Seong-Ho
    • Journal of Periodontal and Implant Science
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    • v.51 no.1
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    • pp.40-52
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    • 2021
  • Purpose: Various crosslinking methods have been introduced to increase the longevity of collagen membranes. The aim of this study was to compare and evaluate the degradation and bone regeneration patterns of 3 collagen membranes. Methods: Four 8-mm-diameter circular bone defects were created in the calvaria of 10 rabbits. In each rabbit, each defect was randomly allocated to 1) the sham control group, 2) the non-crosslinked collagen sponge (NS) group, 3) the chemically crosslinked collagen membrane (CCM) group, or 4) the biphasic calcium phosphate (BCP)-supplemented ultraviolet (UV)-crosslinked collagen membrane (UVM) group. Each defect was covered with the allocated membrane without any graft material. Rabbits were sacrificed at either 2 or 8 weeks post-surgery, and radiographic and histologic analyses were done. Results: New bone formed underneath the membrane in defects in the CCM and UVM groups, with a distinctive new bone formation pattern, while new bone formed from the base of the defect in the NS and control groups. The CCM maintained its shape until 8 weeks, while the UVM and NS were fully degraded at 8 weeks; simultaneously, sustained inflammatory infiltration was found in the margin of the CCM, while it was absent in the UVM. In conclusion, the CCM showed longer longevity than the UVM, but was accompanied by higher levels of inflammation. Conclusions: Both the CCM and UVM showed distinctive patterns of enhancement in new bone formation in the early phase. UV crosslinking can be a biocompatible alternative to chemical crosslinking.

Evaluation of Physical Properties of Ethylene Vinyl Acetate/Silicone Emulsion for Radon Shielding Prepared by Electron-beam Irradiation (전자선 조사에 의해 제조된 라돈 차폐용 ethylene vinyl acetate/silicone 에멀젼의 물리적 특성 평가)

  • Jong-Seok Park;Jang-Gun Lee;Sung-In Jeong;Jun-Pyo Jeon;Yoon-Mook Lim;Jae-Hak Choi;Kap-Soo Kim
    • Journal of Radiation Industry
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    • v.17 no.4
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    • pp.369-375
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    • 2023
  • Radon, a carcinogenic substance generated from soil or building materials, have to be fundamentally blocked from entering indoors. In this study, ethylene vinyl acetate (EVA)/silicone emulsions with excellent mechanical and thermal properties and effective blocking of radon gas were prepared by using radiation technology. As the electron-beam irradiation does increased, a partially crosslinked structure was formed in EVA molecular chain, increasing tensile properties and adhesive strength. The EVA/silicone film showed excellent thermal stability without deformation. In addition, the non-irradiated EVA/silicone film showed a radon blocking rate of about a 75%, while the EVA/silicone film irradiated with 3 and 5 kGy showed an excellent radon blocking rate of over 90% due to the formation of crosslinked structure in the EVA molecular chain. These results indicated that the radiation technology can effectively block radon by forming a partially crosslinked structure of EVA/silicone emulsion to improve tensile property, adhesive strength, and deformation stability.

Ion Permeation in Polyethylene and Ethylene-based Copolymers (폴리에틸렌과 에틸렌계 공중합체에서의 이온투과 현상)

  • 한재홍;박성국;이미경;서광석
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1995.05a
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    • pp.96-99
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    • 1995
  • Ion permeation in polyethylene and ethyene-based copolymers has been investigat-ed Ions permeate faster through non-crosslink-ed films than through crosslinked films. which can be attributed to the decreased chain flexibility and free volume by crosslinking reaction, In EVA/EAA and EVA/ionomer blends, diffusion coefficients of ion decrease with the increase of EAA and ionomer content This was attributed to the increas of acid group acting as ion trapping site in the blends

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Pectin Microspheres for Oral Colon Delivery: Preparation Using Spray Drying Method and In Vitro Release of Release of Indomethacin

  • Lee, Chang-Moon;Kim, Dong-Woon;Lee, Hyun-Chul;Lee, Ki-Young
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.9 no.3
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    • pp.191-195
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    • 2004
  • Drug delivery systems that are based on pectin have been studied for colon specific delivery using the specific activity of colon microflora. The aim of this study was to design a novel method of manufacturing pectin microspheres without oils and surfactants and to investigate the potential use of the pectin microspheres as an oral colon-specific drug carrier. The pectin microspheres were successfully formed using the spray drying method and crosslinking with calcium chloride. From the crosslinked pectin microspheres, indomethacin (IND) release was more suppressed than its release from non-crosslinked microspheres. In a low pH (pH 1.4) environment, the pectin microspheres released IND at an amount of about 18${\pm}$2% of the total loaded weight for 24 h while the release rate of IND was stimulated at neutral pH (pH 7.4). IND release from the pectin microspheres was increased by the addition of pectinase. The results clearly demonstrate that the pectin microspheres that were prepared by the spray drying and crosslinking methods are potential carriers for colon-specific drug deliveries.

A Study on the Application to Anti-corrosive Film of Acryl Emulsion for the Reducing of Environmental Pollutants (환경유해물질 저감을 위한 Acryl emulsion의 방청필름 응용 연구)

  • Lee, S.H.
    • Corrosion Science and Technology
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    • v.8 no.5
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    • pp.197-202
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    • 2009
  • The high toxicity of wax, oil, varnish and volatile corrosion inhibitor(VCI) corrosion inhibitors lead to an increasing interest in using non-toxic alternatives such as anti-corrosive film. This study aims to investigate the possibility to use acryl based anti-corrosive film as a substitution of toxic corrosion inhibitors. Acryl emulsions were polymerized by several acryl monomers(acrylonitrile(AN), n-butyl acrylate(nBA), methylmethacrylate(MMA) and glycycyl methacrylate(GMA)), non-toxic corrosion inhibitor, crosslinking agents(diethylene glycol dimethacrylate(DEGDA)) and various additives in order to apply substrate of anti-corrosive film. Acryl emulsion for anti-corrosive film(AeACF) as a substrate of corrosion inhibitor film has excellent removal characteristic at above $25^{\circ}C$. The crosslinked by DEGDA in a range of above 4 wt% content anti-corrosive film can easily remove from the metal surface by using hands because it kept a balance of cohesion and adhesion strength. Anti - corrosive performance of AeACF is better than anti-corrosive oil by corrosion rate test, which was measured $54.3mg/dm^2$ day(MDD) and $142.9mg/dm^2$ day, respectively. Anti-corrosive film consisting of acryl monomers and inorganic anti-corrosive ingredients did not emit any toxic pollutants by gas chromatography. Thus it is estimated that acryl based anti-corrosion film can substitute toxic corrosion inhibitors.

Molecular Orientation and Optical Properties of Liquid Crystal Mixture Films of Photo-Reactive Mesogens and Non-Reactive Nematic Liquid Crystals (광경화성 액정과 비반응성 네마틱 액정 혼합 필름의 분자 배향 및 광학 특성)

  • Lee, Mong-Ryong;Shin, Mi-Young;Kim, Sung-Hyun;Song, Ki-Gook
    • Polymer(Korea)
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    • v.35 no.5
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    • pp.493-498
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    • 2011
  • Reactive mesogens were used to prepare photo-cured liquid crystal films in which orientations of liquid crystal molecules were preserved by crosslinked networks of cured reactive mesogens. The molecular orientations of liquid crystal mixtures of photo-reative mesogens and non-reactive nematic liquid crystals were studied and compared before and after curing reactions. The effects of temperature and the amount of the non-reactive nematic liquid crystal in the mixture on birefringence of the liquid crystal films were investigated. It was found that optical compensation films with different birefringence could be prepared by controlling the amount of the nematic liquid crystals in the reactive mesogen mixtures.

High Proton Conductivity Crosslinked Sulfonated Polyimide Membranes (높은 수소이온전도성을 가진 가교술폰화폴리이미드막)

  • Lee, Chang-Hyun;Park, Chi-Hoon;Park, Ho-Bum;Lee, Young-Moo
    • Proceedings of the Membrane Society of Korea Conference
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    • 2003.11a
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    • pp.61-63
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    • 2003
  • A major research objective related to proton exchange membrane(PEM) for DMFC is to achieve high proton conductivity over 10$^{-2}$ S/cm, high hydrolytic stability and low methanol permeability with low cost base materials. for the purpose, a lot of thermoplastic polymers such as polysulfones, polyethersulfone, polyetherketones, polyimides, polyoxadiazole, polyphosphazene and polybenzimidazol have been investigated. Amongst those polymers, polyimides have been suggested as a potential PEM due to their excellent thermal, chemical stability and good mechanical properties. Generally, polyimides are synthesized by polycondensation with numerious diamines and dianhydriedes. In our study, polyimide was prepared using non-sulfonated diamine, sulfonated diamine directly synthesized by fuming sulfuric acid, and naphthalenic dianhydride to improve the hydrolysis stability under acidic condition. Through monomer sulfonation-subsequent polymerization method, the high proton conducting capability and the desired sulfonation level were effectively controlled at the same time. To reduce severe methanol transport through the membrane, the chemical crosslinking among polymer chains was introduced using various crosslinking agents with different chain lengths. The crosslinked sulfonated polyimide membranes showed high proton conductivity up to 8.09$\times$10$^{-2}$ S/cm and from crosslinking effect methanol transport through the membranes was considerably reduced as compared with unmodified membranes. For increase of chain length of crosslinker, methanol permeability was adversely reduced to 10$^{-8}$ $\textrm{cm}^2$/s due to decrease of IEC and increase of crosslinking desity.

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Blood Compatibility of Polyurethane-poly(vinyl alcohol) Polymer Blends (폴리우레탄-폴리비닐알콜 블렌드의 혈액적합성)

  • 김승수;유영미;신재섭;정규식
    • Polymer(Korea)
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    • v.24 no.1
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    • pp.82-89
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    • 2000
  • The blood compatibilities of PU/PVA polymer blends with different mixing ratios were evaluated using various methods, such as fibrinogen adsorption, plasma recalcification time, platelet adhesion, whole blood clotting time, and complement activation. In addition, PVA on the surface of the polymer blends was crosslinked by glutaraldehyde to restrain the mobility of PVA molecules for characterizing the effect of PVA in the polymer blends on blood compatibility. The fibrinogen adsorption on the polymer blends decreased with the increase of PVA amount in the polymer blends. The plasma recalcification times of the polymer blends with 10-50 wt% PVA were longer than those of PU, PVA, and polymer blends with higher amount of PVA. The morphological changes and adhesion of platelets on the polymer blends with 30-50 wt% PVA were less than those on the other materials. The blood clotting times and complement activation on the polymer blends with 30-50 wt% PVA were reduced, compared to the other materials. On the other hand, the blood compatibility of the crosslinked polymer blends was relatively decreased, compared to the non-crosslinked ones. According to these experimental results, the blood compatibility of the polymer blends with 30-50 wt% PVA was better than that of the other materials and such a blood compatibility of the polymer blends might be related to the mobility of PVA molecules on the surface.

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Preparation and Characterization of Nanofiltration Membrane for Recycling Alcoholic Organic Solvent (알코올성 유기용매 재활용을 위한 나노여과막의 제조와 특성평가)

  • Kim, Seong Heon;Im, Kwang Seop;Kim, Ji Hyeon;Koh, Hyung Chul;Nam, Sang Yong
    • Membrane Journal
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    • v.31 no.3
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    • pp.228-240
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    • 2021
  • The organic solvent robust polybenzimidazole (PBI) membranes were prepared as organic solvent nanofiltration (OSN) membrane for the recycling of alcoholic solvents using non-solvent induced phase separation with different dope solution concentration and coagulant composition of water/ethanol mixtures to control the membrane morphology and permeation performance. Investigation on crosslinking of polybenzimidazole indicated that the membrane crosslinked with dibromoxylene (DBX) had enough mechanical strength and solvent resistance to be applied as a OSN membranes. The crosslinked PBI membrane prepared by more than 20wt% dope concentration coagulated in water showed a rejection of > 90% to Congo Red (MW of 696.66 g/mol) while pure ethanol permeances was more than 22.5 LMH/bar at 5 bar. Investigation on coagulant composition indicated that ethanol permeance through crosslinked PBI OSN membrane increased with increasing of ethanol concentration in water/ethanol mixture coagulants.

A Study on AC Breakdown and Conduction Characteristics of Environmental-friendly Non-crosslinked Polyethylene (친환경 비가교 폴리에틸렌의 절연파괴와 전도특성에 관한 연구)

  • Kong, Tae-Sik;Kwon, Ki-Hyung;Kim, Seong-Jung;Cho, Kyu-Cheol;Lee, Jae-Soon;Ku, Kwang-Hoi;Lee, June-Ho
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.1426-1427
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    • 2011
  • 전기적, 기계적으로 우수한 성능을 지닌 절연재료인 폴리에틸렌은 장기간 운전 중 열화에 의해 절연성능이 저하되고 시간이 지나면서 케이블의 사고 원인을 제공하게 된다. 본 논문에서 전력용 케이블의 절연체로 널리 사용되고 있는 가교폴리에틸렌(XLPE)를 대신하여 최근 주목을 받고있는 친환경 특성을 부여하기 위한 비가교 폴리에틸렌 재료에 대한 기초적 물성(워터트리성장특성, AC 절연파괴특성, 전도전류 특성)을 실험적으로 비교분석하였다.

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