• Polymer(Korea)
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• v.32 no.1
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• pp.26-30
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• 2008

This study was designed to investigate the effect of hybridization of synthetic/natural materials for annulus fibrosus (AF) tissue regeneration in vitro and in vivo. The synthetic/natural hybrid scaffolds were prepared using PLGA (poly (lactic-co-glycolic) acid), SIS (small intestinal submucosa) and DBP (demineralized bone particles). PLGA, PLGA/SIS(20%), PLGA/DBP(20%) and PLGA/SIS (10%)/DBP (10%) scaffold were manufactured by solvent casting/salt leaching method. Compressive strength was measured. Rabbit AF cells were isolated, cultured and seeded into experimental groups. Hydroxyproline production and DNA quantity of AP cells on each scaffold was measured at 2, 4 and 6 weeks after in vitro culture. Cell-scaffold composites were implanted subcutaneously into athymic mice. After 1,4 and 6 weeks postoperatively, specimens were taken and H&E, Safranin-O and type I collagen staining were carried out concerning formation of cartilagenous tissue. In vitro PLGA/SIS scaffold was evaluated for total collagen content (bydroryproline/DNA content) and PLGA scaffold was evaluated for compressive strength.

• Environmental Engineering Research
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• v.22 no.3
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• pp.255-265
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• 2017

Polyelectrolytes are commonly used as flocculants in drinking water treatment. However the growing concerns about their toxicity have motivated the search for biocompatible flocculants. Here, we show that gelatin, a natural amphoteric polyelectrolyte, can be effectively adsorbed on clay surfaces and can potentially be a suitable substitute for existing flocculants. The adsorption of gelatin from its aqueous solution onto the mineral clay surfaces at different conditions was systematically investigated using the design of experiments methodology. The gelatin adsorption was found to vary considerately with pH variation showed a maximum adsorption at its isoelectric point. The amount of adsorbed gelation increased with increasing pH from 3 to 5, attained a maximum at pH 5 and then decreased with increasing pH from 5 to 11. Similarly, the amount of adsorbed gelatin showed decreasing trends around salt concentration of 0.05 M and temperature $35^{\circ}C$. On the other hand, the adsorption was continuously increased with time and polymer concentration in the range of 0.1-0.9 mg/dL. Finally, the jar tests confirmed the ability of gelatin for using a natural flocculant for water treatment.

• Elastomers and Composites
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• v.33 no.3
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• pp.159-167
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• 1998

Rubber products are aged like human complexion by the attack of oxygen, ultra violet, ozone, etc.. Aging is very important and also very complicated phenomenon to understand. This may explain the rarity of papers on this subject. In this study, we tried to understand the aging behavior of EPDM compared to that of natural rubber. We also compared the sulfur vulcanized system to the peroxide vulcanized one. In our experiment, the peroxide vulcanizates were more advantageous in aging than the sulfur vulcanizates. The authors belived that this study about the high performance EPDM would be applicable to rubber industry.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.1091-1093
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• 2010

• Elastomers and Composites
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• v.46 no.3
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• pp.186-194
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• 2011

Natural fiber/natural rubber composites were fabricated by uniformly compounding natural rubber and cellulose- based natural fiber kenaf and then by compression molding. The effect of kenaf fiber content on their vulcanization behavior, hardness, tensile properties, tear strength and static and dynamic properties was investigated. The contents of kenaf fiber in the composites were 0, 5, 10, 15, and 20 phr, compared to natural rubber and additives. The result indicated that various properties of natural rubber depended on the kenaf fiber content. With increasing kenaf fiber content, the torque for vulcanization of natural rubber was increased whereas the vulcanization time was reduced as well. The hardness, tensile modulus and tear strength of kenaf/natural rubber composites were gradually decreased with the fiber content whereas the tensile strength and elongation at break were decreased. Also, with increasing the kenaf fiber content the dynamic property of natural rubber was changed more greatly than the static property. The loss factor, which is closely related with the damping or absorption of the energy given to natural rubber, was proportionally increased with the fiber content.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.46-47
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• 2006

Vascularization is essential for success in regenerative medicine. We have developed in vitro models to study how human microvascular endothelial cells (EC) and endothelial progenitor cells (EPC) colonize polymer scaffolds and express the endothelial phenotype, including angiogenesis. Examples are given of supportive growth and differeniation of EC on microfibre meshes of the silk protein fibroin and blends of starch with poly(epsilon-caprolactone), phenotypic markers being studied at both protein and mRNA level. Experimental models are also shown and concepts discussed to investigate how the stem cell niche, including that responsible for vascularization could be targeted, for example, by using engineered biodegradable polymer nanoparticles.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.353-353
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• 2006

Deoxyribonucelic acid (DNA) molecules have a huge molecular weight so that DNA was reported to be a promising natural polymer to give durable films. Among many applications of DNA, the authors focused their attention on separation membranes derived from DNA because membranes will play an important role in environmental and energy related processes. DNA-polyion complex membranes were prepared from DNA and corresponding polycations. The DNA-polyion complex membranes showed chiral separation ability toward racemic amino acid mixtures.

• Transactions on Electrical and Electronic Materials
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• v.4 no.1
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• pp.11-14
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• 2003

The regularities of immobilization of natural medicinal substances - alchidine on gels of poly(vinyl alcohol) - are investigated. It is shown that the polymer components of alchidine interact with nonionic polymer with formation of interpolymer complexes. The influence of the different factors on the properties of complexes is considered and the constants of alchidine distribution in the system gel - water are calculated.

• Journal of Integrative Natural Science
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• v.2 no.2
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• pp.69-72
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• 2009

Pentiptycenediacetylene is very useful precursor materials for the synthesis of conducting polymer materials. The incorporation of rigid three-dimensional pentiptycene moieties into conjugated polymer backbones would offer several design advantages. They prevent ${\pi}$-stacking of the polymer backbones and thereby maintain high fluorescence quantum yields and spectroscopic stability in thin films. The pentiptycenediactylene was synthesized and characterized by 1H- and 13C-NMR spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1915-1918
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• 2006