• Title/Summary/Keyword: Biological properties

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Mechanical properties of epoxy composites reinforced with ammonia-treated graphene oxides

  • Park, Mi-Seon;Lee, Sangmin;Lee, Young-Seak
    • Carbon letters
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    • v.21
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    • pp.1-7
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    • 2017

  • The effects of ammonia-treated graphene oxide (GO) on composites based on epoxy resin were investigated. Ammonia solutions of different concentrations (14-28%) were used to modify GO. Nitrogen functional groups were introduced on the GO surfaces without significant structural changes. The ammonia-treated GO-based epoxy composites exhibited interesting changes in their mechanical properties related to the presence of nitrogen functional groups, particularly amine ($C-NH_2$) groups on the GO surfaces. The highest tensile and impact strength values were 42.1 MPa and 12.3 J/m, respectively, which were observed in an epoxy composite prepared with GO treated with a 28% ammonia solution. This improved tensile strength was 2.2 and 1.3 times higher than those of the neat epoxy and the non-treated GO-based epoxy composite, respectively. The amine groups on the GO ensure its participation in the cross-linking reaction of the epoxy resin under amine curing agent condition and enhance its interfacial bonding with the epoxy resin.

  • https://doi.org/10.5714/CL.2017.21.001 인용 PDF KSCI

Archeological Consideration of DNA Typing (유전자 분석의 고고학적 고찰)

  • Lee, Kyu-Sik;Seo, Min-Seok;Chung, Yong-Jae
    • Korean Journal of Heritage: History & Science
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    • v.35
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    • pp.120-137
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    • 2002

  • It has not been a long time since we recognize that a word 'DNA' is not unfamiliar with us. Development of biology give us so much of benefits of civilization and so we call the 21th century as 'biological period'. It has not been a long time that archeology made contact with biology. With biological development, DNA typing analysis has been accomplished extensively since 1990's. We know through mitochondrial DNA base sequencing analysis that the Neanderthal man is not the origin of the human race and ancient human race set out from Africa. Biological science technology, which is polymerase chain reaction(PCR) or electrophoresis etc., made these results possible. A contact between biology, especially genetics, and archeology is getting accomplished through these current. If genetics keep in contact with archeological foundation, we know not only about ancient populations in the Korean Peninsula, but also origin of human race. This field is so-called 'DNA Archeology'. This field is of help to person identification and children discrimination as like a forensic science. We make every effort for great possibilities from co-ownership of these two fields and these fields needs to convert a recognition, especially.

  • https://doi.org/10.22755/kjchs.2002.35.120 인용 PDF

Cross-Linked Collagen Scaffold from Fish Skin as an Ideal Biopolymer for Tissue Engineering

  • Biazar, Esmaeil;Kamalvand, Mahshad;Keshel, Saeed Heidari;Pourjabbar, Bahareh;Rezaei-Tavirani, Mustafa
    • Korean Journal of Materials Research
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    • v.32 no.4
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    • pp.186-192
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    • 2022

  • Collagen is one of the most widely used biological materials in medical design. Collagen extracted from marine organisms can be a good biomaterial for tissue engineering applications due to its suitable properties. In this study, collagen is extracted from fish skin of Ctenopharyngodon Idella; then, the freeze drying method is used to design a porous scaffold. The scaffolds are modified with the chemical crosslinker N-(3-Dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride (EDC) to improve some of the overall properties. The extracted collagen samples are evaluated by various analyzes including cytotoxicity test, SDS-PAGE, FTIR, DSC, SEM, biodegradability and cell culture. The results of the SDS-PAGE study demonstrate well the protein patterns of the extracted collagen. The results show that cross-linking of collagen scaffold increases denaturation temperature and degradation time. The results of cytotoxicity show that the modified scaffolds have no toxicity. The cell adhesion study also shows that epithelial cells adhere well to the scaffold. Therefore, this method of chemical modification of collagen scaffold can improve the physical and biological properties. Overall, the modified collagen scaffold can be a promising candidate for tissue engineering applications.

  • https://doi.org/10.3740/MRSK.2022.32.4.186 인용 PDF KSCI

Selection and Directed Evolution of New Microbial Biocatalysts and Their Application to Organic Synthesis

  • Asano, Yasuhisa
    • Journal of Applied Biological Chemistry
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    • v.43 no.4
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    • pp.207-210
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    • 2000

  • As a typical example of the screening for a microbial biocatalyst from nature, isolation of nitrilesynthesizing microorganisms, characterization of a new enzyme aldoxime dehydratase, and its function in the aldoxime-nitrile pathway are introduced. Catalytic properties of some of our enzymes were improved through a direct evolutionary approach.

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