• 폴리머
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• 제35권6호
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• pp.526-530
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• 2011

바이오매스에서 유래된 2,5-dihydroxymethylfuran(DHMF)을 $KMnO_4$ 산화반응으로 furan-2,5-dicarboxylic acid(FDCA)를 합성하였다. 합성한 FDCA와 다이올류를 에스테르화 반응과 축중합 반응을 진행시켜 폴리에스터를 중합하였다. 폴리에스터는 NMR을 통해 조성을 분석하였고 DSC와 TGA를 통해 열적특성을 분석하였다. 합성된 폴리에스터의 고유점도는 0.78~1.2 dL/g으로 상용화된 poly(ethylene terephthalate)(PET)와 비슷하였다. 다이올의 길이가 증가할수록 Young's modulus와 strength는 낮아지고 elongation-to-break는 높아지는 경향을 확인하였다. 합성한 poly(ethylene furandicarboxylate)(PEF)의 Young's modulus는 3551 MPa, strength는 103 MPa로 상용화된 PET와 비슷하였다.

• 전기학회논문지
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• 제65권5호
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• pp.819-824
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• 2016

The accelerated thermal aging of CSPE (chlorosulfonated polyethylene) was carried out for 33.64 and 67.27 days at 110[$^{\circ}C$], equivalent to 40 and 80 years of aging at 50[$^{\circ}C$], respectively. These samples were referred to as CSPE-0y, CSPE-40y and CSPE-80y, respectively. As the accelerated thermally aged years of the CSPE increase, the insulation resistance[$\Omega$] at 20[Hz], 500[Hz], and 2[KHz], and the percent elongation [%EL] of the CSPE decrease. However, the dissipation factor($tan{\delta}$) at 20[Hz], 500[Hz], and 2[KHz], the apparent density[$g/cm^3$], the glass transition temperature and the melting temperature of the CSPE were increased. The period of time that the voltage has to be applied until electric breakdown of the CSPE-0y is longer than that of the CSPE-40y, and the CSPE-80y, but the dielectric strength of the CSPE-80y is lower than that of the CSPE-0y and the CSPE-40y. The differential temperatures after the AC and DC voltages are applied to CSPE-0y, CSPE-40y and CSPE-80y are 0.026~0.028[$^{\circ}C$], 0.030~0.042[$^{\circ}C$], 0.018~0.045[$^{\circ}C$], respectively. The variations of temperature for the AC voltage are higher than those for the DC voltage when an AC voltage is applied to CSPE-0y, CSPE-40y and CSPE-80y. It is found that the dielectric loss owing to the dissipation factor[$tan{\delta}$] is related to the electric dipole conduction current. It is ascertained that the ionic (electron or hole) leakage current is increased by the separation of the branch chain of CSPE polymer from the main chain of the polyethylene as a result of thermal stress due to accelerated thermal aging as well as by conducting ions such as $Na^+$, $Cl^-$, $Mg^{2+}$, $SO_4^{2-}$, $Ca^{2+}$ and $K^+$ after seawater soaking.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.915-922
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• 2017

내열 및 내유성 고무복합체 특성연구(The study on the thermal and oil resistance rubber composite), 2016.[6] 연구에서는 고온($150^{\circ}C$, $175^{\circ}C$, $200^{\circ}C$) 조건의 고온촉진노화를 통하여 불소고무 복합체의 수명을 예측하였다. 일반적인 고무제품은 온도, 습도, 오존, 빛, 유제, 기계 및 전기적 응력 등의 특성저하 인자에 따라 다른 특성을 나타낼 가능성이 있으며, 이러한 문제를 해결하기 위하여 "내열 및 내유성 고무복합체 특성연구"[6] 연구에서 얻어진 고온촉진노화에 의한 수명 예측값과 저온촉진노화간의 인장강도 변화율 및 신장률 변화율 그리고 부피 변화율, 무게 변화율, 두께 변화율 및 열전도도를 비교 검토하였다. 검토 결과, 요구 한계수명은 모두 만족하였지만 고온촉진노화 결과와 저온촉진노화 결과 간 변화율에서 약간의 격차를 보였다. 이러한 변화율 격차가 일어나는 원인은 고온촉진노화에서는 노화 시 불소고무의 주사슬 분해로 인하여 인장강도, 신장률 감소 및 부피, 무게, 두께 증가가 일어나는데 비해 저온촉진노화에서는 $80^{\circ}C$에서 불소고무의 지속적 경화반응으로 인하여 인장강도, 신장률 및 부피, 무게, 두께 변화가 적게 나타났을 것으로 판단된다.

• Journal of Microbiology and Biotechnology
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• 제28권9호
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• pp.1527-1535
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• 2018

Bacterial strain BAS23 was isolated from rice field soil and identified as Bacillus amyloliquefaciens. Based on dual culture method results, the bacterium BAS23 exhibited potent in vitro inhibitory activity on mycelial growth against a broad range of dirty panicle fungal pathogens of rice (Curvularia lunata, Fusarium semitectum and Helminthosporium oryzae). Cell-free culture of BAS23 displayed a significant effect on germ tube elongation and mycelial growth. The highest dry weight reduction (%) values of C. lunata, H. oryzae and F. semitectum were 92.7%, 75.7%, and 68.9%, respectively. Analysis of electrospray ionization-mass spectrometry (ESI-MS) and $^1H$ nuclear magnetic resonance (NMR) spectroscopy revealed that the lipopeptides were iturin A with a C14 side chain (C14 iturinic acid), and a C15 side chain (C15 iturinic acid), which were produced by BAS23 when it was cultured in nutrient broth (NB) for 72 h at $30^{\circ}C$. BAS23, the efficient antagonistic bacterium, also possessed in vitro multiple traits for plant growth promotion and improved rice seedling growth. The results indicated that BAS23 represents a useful option either for biocontrol or as a plant growth-promoting agent.

• 생명과학회지
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• 제14권4호
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• pp.644-649
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• 2004

GA 생합성에 결정적 역할을 하는 GA 3$\beta$-hydroxylase를 pIG121-Hm 벡터에 GUS유전자를 빼고 antisense로 클로닝하여 이를 동진벼에 도입한 결과 17개체의 절간신장이 억제된 형질전환한 식물체를 얻을 수 있었다. 일반 재배 동진벼를 대조군으로 하여 비교하였을때 antisense GA 3$\beta$-hydroxylase 유전자가 형질 도입된 식물체의 획득형질은 평균적으로 대조군에 비해 절간 신장의 억제가 확인되었다. 절간신장의 억제가 보인 개체의 엽육조직을 co취하여 Southen blot hybridization분석 결과 3개의 line에서 모두 single copy로 도입된 것으로 나타났다. 이로써$T_o$ 식물체 내에 antisense GA 3$\beta$-hydroxylase 유전자를 내포하고 있는 것으로 확인되었다. 이것은 antisense GA 3$\beta$-hydroxylase 유전자가 생체내에서 직접 또는 간접적으로 GA 3$\beta$-hydroxylase유전자의 발현에 관여한 것이라 사료되어진다.

• Fibers and Polymers
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• 제4권3호
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• pp.114-118
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• 2003

The prepolymer and the final polyurethane (PU) block copolymer were synthesized by reacting 4,4-methylene bis(phenylisocyanate) with poly(tetramethylene glycol) and the prepolymer with 1,4-butanediol as a chain extender, respectively, to investigate the relation between phase separation and it's resulting properties. According to FT-IR data, the phase separation of hard and soft segments in the prepolymer and the PU block copolymer grew bigger by increasing the hard segment content, and the PU showed more dominant phase separation than the prepolymer. The heat of fusion due to soft segments decreased in both the prepolymer and the PU by increasing the hard segment content, whereas the heat of fusion due to hard segments increased in the PU did not appear in the prepolymers. The breaking stress and modulus of the prepolymer increased by increasing the hard segment content, and the elongation at break decreased gradually, and the PU showed the highest breaking stress and modulus at 58% hard segment content. However, the best shape recovery of the PU was obtained at 47% hard segment content due to the existence of proper interaction among the hard segments for shape memory effect. Consequently, the mechanical properties and shape memory effect of the PU were influenced by the degree of phase separation, depending on the incorporation of chain extender as well as the hard segment content.

• 대한화학회지
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• 제55권4호
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• pp.673-679
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• 2011

지글러-나타 촉매를 사용하여 에틸렌을 중합함으로써 다양한 공단량체의 종류와 조성을 갖는 이중 분자량 분포의 고밀도 폴리에틸렌이 합성되었다. 이들의 구조와 물성을 GPC, NMR, DSC, 인장 측정기를 이용하여 연구하였다. 에틸렌/1-헥센 공중합체가 에틸렌/1-부텐 공중합체보다 비슷한 조성을 가질 경우 높은 인장강도와 파단연신율을 가짐을 확인 하였다. 분자량은 고분자의 공단량체 비율이 증가할수록 감소하였다. 짧은 곁사슬은 결정화도에 영향을 주어 결과적으로 이중 분자량 분포를 갖는 고밀도 폴리에틸렌의 모폴로지와 기계적 물성에 영향을 미쳤다. SSA로 처리 후 다수의 발열 곡선이 관찰되었으며 이는 주로 에틸렌 배열길이와 라멜라 두께의 불균일성에 기인한다. 분포지수의 차이로부터 공단량체의 조성이 높은 폴리에틸렌의 SCB 분포가 균일도를 향상시킴을 알 수 있었다.

• 환경생물
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• 제27권4호
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• pp.391-396
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• 2009

The biological effects of carcinogenic polycyclic aromatic hydrocarbons (cPAHs) including benzo[a]pyrene (BaP), dibenzo[a,h]anthracene (DBA), benzo[a]anthracene (BaA), benzo[b] fluoranthene (BbF), benzo[k]fluoranthene (BkF), and indeno[1,2,3-c, d]pyrene (InP) on transcriptomic changes were determined in the liver of Oryzias latipes. Differentially expressed genes (DEGs) by binary exposure to cPAHs (BaP+BaA, BaP+BbF, BaP+BkF, BaP+DbA, BaP+InP) were screened by annealing control primers-based polymerase chain reaction followed by sequence analysis and BLAST searching. The results showed that four DEGs were commonly expressed by cPAHs and they were identified as ribosomal protein S4, coagulation factor II, elongation factor 1 beta, and a predicted protein similar to human immunodeficiency virus type I enhancer binding protein 3. This finding suggests that binary exposure to cPAHs interferes protein synthesis required for fundamental liver functions in fish.

• 한국미생물·생명공학회지
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• 제46권2호
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• pp.91-101
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• 2018

The aim of this study was to transfer the 18.5 kb gene clusters coding for 17 genes from Lactobacillus rhamnosus to Lactococcus lactis subsp. cremoris MG1363 in order to determine the effect of host on exopolysaccharide (EPS) production and to provide a model for studying the phosphorylation of proteins which are proposed to be involved in EPS polymerization. Lactobacillus rhamnosus RW-9595M and ATCC 9595 have 99% identical operons coding for EPS biosynthesis, produced different amounts of EPS (543 vs 108 mg/l). L. lactis subsp. cremoris MG1363 transformed with the operons from RW-9595M and ATCC 9595 respectively, produced 326 and 302 mg/l EPS in M17 containing 0.5% glucose. The tyrosine protein kinase transmembrane modulator (Wzd) was proposed to participate in regulating chain elongation of EPS polymers by interacting with the tyrosine protein kinase Wze. While Wzd was found in phosphorylated form in the presence of the phosphorylated kinase (Wze), no phosphorylated proteins were detected when all nine tyrosines of Wzd were mutated to phenylalanine. Lactococcus lactis subsp. cremoris could produce higher amounts of EPS than other EPS-producing lactococci when expressing genes from L. rhamnosus. Phosphorylated Wzd was essential for the phosphorylation of Wze when expressed in vivo.

• Journal of Microbiology and Biotechnology
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• 제13권5호
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• pp.823-827
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• 2003

Streptomyces venezuelae ATCC 15439 is notable in its ability to produce two distinct groups of macrolactones. It has been reported that the generation of two macrolactone structures results from alternative expression of pikromycin (Pik) polyketide synthase (PKS). It was previously reported that the hybrid pikromycin-tylosin PKS can also produce two different macrolactones but its mechanistic basis remains unclear. In order to address this question, a series of site-directed mutagenesis of tentative alternative ribosome binding site and translation start codons in tylGV were performed. The results suggest that macrolactone ring size is not determined by the alternative expression of TylGV but through other mechanism(s) involving direct interaction between the PikAIII and TE domain or skipping of the final chain elongation step. This provides new insight into the mechanism of macrolactone ring size determination in hybrid PKS as well as an opportunity to develop novel termination activities for combinatorial biosynthesis.