• 멤브레인
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• 제28권5호
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• pp.326-331
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• 2018

축전식 탈염(capacitive deionization)에 이용할 수 있는 폴리페닐렌 옥사이드(PPO) 음이온 교환막의 가교결합에 대해 조사하였다. 브롬화와 아민화 반응단계를 거쳐 PPO 음이온 교환 고분자를 제조하고 비스페놀 A 디글리시딜에테르(BADGE), m-페닐렌디아민(m-PDA), 헥사메틸렌디아민(HMDA) 등으로 가교하였다. 가교에 따른 겔화되는 시간은 HMDA > m-PDA > BADGE 순으로 짧았으며, 일정한 함량 이상으로 실온에서 가교하면 1-메틸피롤리돈(NMP)과 같은 비양성자성 용매(aprotic solvent)에 녹지 않아 내화학성이 증대되었다. 가교제(BADGE) 함량에 따른 음이온 교환막의 이온 교환 용량과 함수율을 측정하고 비교하였다. HMDA 용액에 침적하여 표면 가교한 PPO 음이온 교환막을 축전식 탈염에 적용한 결과 그 탈염 성능은 가교하지 않은 막과 비교하여 흡착단계의 초기 부분을 제외하고 거의 차이가 없었다.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1195-1201
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• 2004

Tyrosinase was covalently immobilized on platinum electrode according to the method we developed for laccase (Bull. Korean Chem. Soc. 2002, 23(7), 385) and p-chlorophenol, p-cresol, and phenol could be detected with sensitivities of 334, 139 and 122 nA/ ${\mu}M$ and the detection limits of 1.0, 2.0, and 2.5 ${\mu}M$, respectively. The response time ($t_{90\%}$) is 3 seconds for p-chlorophenol, and 5 seconds for p-cresol and phenol. The optimal pHs of the sensor are in the range of 5.0- 6.0. This sensor can tolerate at least 500 times repeated injections of p-chlorophenol with retaining 80% of initial activity. In case of tyrosinase and laccase co immobilized platinum electrode, the sensitivities are 560 nA/ ${\mu}M$ for p-phenylenediamine (PPD) and 195 nA/ ${\mu}M$ for p-chlorophenol, respectively. The sensitivity of the bi-enzyme sensor for PPD increases 70% compared to that of only laccase immobilized one, but the sensitivity for p-chlorophenol decreases 40% compared to that of only tyrosinase immobilized one. The sensitivity increase for the bi-enzyme sensor for PPD can be ascribed to the additional catalytic function of the co-immobilized tyrosinase. The sensitivity decrease for p-chlorophenol can be explained by the “blocking effect” of the co-immobilized laccase, which hinders the mass transport through the immobilized layer. If PPD was detected with the electrode that had been used for p-chlorophenol, the sensitivity decreased 20% compared to that of the electrode that had been used only for PPD. Similarly, if p-chlorophenol was detected with PPD detected electrode, the sensitivity also decreased 20%. The substrate-induced conformation changes of the enzymes in a confined layer may be responsible for the phenomena.

• 대한화학회지
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• 제18권1호
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• pp.50-57
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• 1974

芳香族디아민을 강한 광물산의 妓質中에서 디아조化하고, 이때 얻은 테트라아조늄염을 還元함으로서 芳香族 디히드라진類의 合成에 응용할 수 있는 실용적인 方法을 創案하였다. 파라페닐렌디아민을 진한 鹽酸 또는 45% 過鹽素酸을 妓質로 해서 低溫에서 아질산나트륨으로디아조化하여 얻은 테트라아조늄鹽을 염화주석(II)으로 還元하여 파라페닐렌디히드라진(PPDH)을 鹽酸鹽의 微細한 針狀結晶으로 分離하였다. PPDH의 遊離鹽期는 空氣中에서 酸化되기 쉽기 때문에不安定하여 分離할수 없었다. PPDH${\cdot}$2HCl은 明確한 융점을 보이지 않고 $^180{\circ}C$에서 炭化되면서 分解하였다. PPDH는 芳香族 모노히드라진과 유사한 性質이 있었으며, 초산염의 緩衝溶液에서 알데히드 및 케톤과 반응시키면 재빨리 反應하여 노랑색 내지 갈색을 띤 縮合化合物인 디히드라존이 生成되었다. 이것은 PPDH가 디카르보닐化合物과 反應하여 高分子의 폴리마나 還狀縮合物을 形成할 것임을 暗示한다.

• 한국식품과학회지
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• 제11권2호
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• pp.77-80
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• 1979

녹차중(綠茶中)의 L-ascorbic acid를 정량(定量)함에 있어서 흔히 사용되고 있는 DNP법(法)을 적용할 때 불순물(不純物)에 의한 방해(妨害)여부와 그의 제거방법(除去方法)에 대하여 검토(檢討)한 결과(結果)는 다음과 같다. 즉, DNP법(法)으로 AsA를 측정시 ethyl glyoxal, diacetyl, caffeine둥 불순물질 및 아미노산(酸)들이 방해하였으며, 이들 물질을 제거하는 수단으로 브롬산화(酸化)후 o-phenylenediamine을 반응시킨 다음 chloroform으로 추출제거(抽出除去)하고 Amberlite $IR-120(H^{+})$로 아미노산(酸)을 제거(除去)한 후에 DNP법(法)으로 비색정양(比色定量)하면 L-ascorbic acid 함량(含量)을 정확히 측정(測定)할 수 있었다. 또한 분석소요시간(分析所要時間)이 TLC법(法)에 비해서 현저히 단축되고 재현성(再現性)도 좋아서 녹차중(綠茶中)의 ascorbic acid 정량(定量)에는 본법(本法)이 적합함을 확인하였다.

• 한국식품과학회지
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• 제8권2호
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• pp.85-89
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• 1976

Gas chromatography를 이용하여 methylglyoxal, diacetyl 및 triose reductone과 같은 dicarbonyl류(類)를 분리측정(分離測定)할 수 있는 조건(條件)을 실험(實驗)하였던 바 다음과 같은 결과(結果)를 얻었다. 1. MG, DAc, DTR의 혼합물(混合物)에 OPD를 반응시켜 quinoxaline 유도체(誘導體)를 만들고 이것을 클로로포름으로 추출(抽出)하면 MG 및 DAc는 거의 100%추출(抽出)되었고, DTR은 에틸에테르에 추출(抽出)되었다. 2. SE-30을 충진제로하여 얻어진 column 조건(條件)에서 MG-OPD와 DAc-OPD는 완전히 분리측정(分離測定)할 수 있었다. 3. 당류중(糖類中) glucose의 OPD 축합물형성조건(縮合物形成條件)은 D-glucose 180mg을 0.1N-NaOH 용액 10ml에서 5분간(分間) 가열후 OPD와 반응(反應)시켜 pH 6. 0에서 클로로포름으로 추출(抽出)하여 GLC에 겉면 5개의 peak가 나타났고, 그 중에서 2개는MG-OPD와 DAo-OPD임을 확인하였다. 그러나 중성(中性) 및 산성가열(酸性加熱)인 경우는 peak가 확실치 않았다.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2005년도 춘계학술발표회 논문집
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• pp.213-215
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• 2005

The metal complexes can be influenced not only by the central metal atoms and the substituent groups, but also by the native of the chelating atoms. For example, near-infrared absorbing chromophores were synthesized by the reaction of phenylenediamine derivatives with a solution of pottassium hydroxide followed by the addition of nickel(II) chloride. These dyes provide absorbing infrared light over 780-840 nm with an extinction coefficient of $2.5-6.0{\times}10^4$. By introduction of alkyl, alkoxyl, cyano, and other functional group into the parent dye, these dyes greatly improved the solubility in organic solvent. New near-infrared absorbing donor-acceptor chromophores have been investigated by varying the electron donating and accepting strength of the two halves of the molecule. The cyanine chromophores permit the simplest way of obtaining systems that absorb well into the near-infrared region of the spectrum. Cyanine dyes possess high extinction coefficients that initially increase with Increasing chain length. These chromophores could be useful in near-infrared optical materials.

• The Korean Journal of Physiology and Pharmacology
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• 제2권3호
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• pp.369-376
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• 1998

This report shows that hydroxyl radical, generated by a Fenton reaction involving adenosine $5'-diphosphate/Fe^{2+}$ complex ($5-15\;{\mu}M$) and $H_2O_2$ ($2\;{\mu}M$), induced differentiation of HL-60 cells in a dose- and time-dependent manner. This is evidenced by the increases in 12-O-tetradecanoylphorbol 13-acetate- and fMLP-stimulated superoxide production capability. The cells exposed to hydroxyl radical for defined periods (24∼96 hr) continued to differentiate even after the hydroxyl radical generating system had been removed. The differentiated cells displayed fMLP-stimulated calcium mobilization and increased expression of myeloid-specific antigen CD11b and CD14. The extent of the differentiation was markedly reduced by desferrioxamine ($100\;{\mu}M$), dimethylthiourea (5 mM), N,N'-diphenyl-1,4-phenylenediamine ($2\;{\mu}M$), and N-acetyl-L-cysteine (5 mM). The induction of differentiation by hydroxyl radical was enhanced by 3-isobutyl-1-methylxanthine ($200\;{\mu}M$) and Ro-20-1724 ($8\;{\mu}M$), and inhibited by dipyridamole (2 ${\mu}M$). These results suggest that hydroxyl radicals may induce commitment of HL-60 cells to differentiate into more mature cells of myelomonocytic lineage through specific signal-transduction pathway that is modulated by phosphodiesterase inhibitors.

• Tribology and Lubricants
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• 제31권6호
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• pp.258-263
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• 2015

Biodiesel is an environmentally-friendly fuel with low smoke emission because it contains about 10% oxygen. Biodiesel fuel prepared by transesterification of vegetable oil or animal fats is susceptible to auto-oxidation. The rate of auto-oxidation depends on the number of methylene double bonds contained within the fatty acid methyl or ethyl ester groups. Biodiesel may be easily oxidized under several conditions, i.e., upon exposure to sunlight, temperature, oxygen environment. Maintenance of the fuel quality of biodiesel requires the development of technologies to increase the resistance of biodiesel to oxidation. Treatment with antioxidants is a promising approach for extending the shelf-life or storage time of biodiesel. The chemical properties of various amine-based antioxidants were evaluated after synthesis of the antioxidants by condensation of phenylenediamine with alkylamines at room temperature. In general, the oxidative stability can be assessed based on various experimental parameters. Such parameters may include temperature, pressure, and the flow rate of air through the samples. The Rancimat method (EN14112) was selected because it is a rapid technique that requires very little sample and provides good precision for oxidative degradation analysis. Specifically, the EN 14112 technique provides enhanced efficiency for oxidative stability evaluation when a larger ester head group is utilized. Therefore, this technique was employed for evaluation of the oxidation stability of biodiesel by the Rancimat method (EN14112).

• 대한임상검사과학회지
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• 제41권2호
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• pp.83-92
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• 2009

This study was undertaken to examine the effect of oxidants on membrane transport function in renal epithelial cells. Hydrogen peroxide ($H_2O_2$) was used as a model oxidant and the membrane transport function was evaluated by measuring $Na^+$-dependent phosphate ($Na^+$-Pi) uptake in opossum kidney (OK) cells. $H_2O_2$ inhibited $Na^+$-Pi uptake in a dose-dependent manner. The oxidant also caused loss of cell viability in a dose-dependent fashion. However, the extent of inhibition of the uptake was larger than that in cell viability. $H_2O_2$ inhibited $Na^+$-dependent uptake without any effect on $Na^+$-independent uptake. $H_2O_2$-induced inhibition of $Na^+$-Pi uptake was prevented completely by catalase, dimethylthiourea, and deferoxamine, suggesting involvement of hydroxyl radical generated by an iron-dependent mechanism. In contrast, antioxidants Trolox, N,N'-diphenyl-p-phenylenediamine, and butylated hydroxyanisole did not affect the $H_2O_2$ inhibition. Kinetic analysis indicated that $H_2O_2$ decreased Vmax of $Na^+$-Pi uptake with no change in the Km value. Phosphonoformic acid binding assay did not show any difference between control and $H_2O_2$-treated cells. $H_2O_2$ also did not cause degradation of $Na^+$-Pi transporter protein. Reduction in $Na^+$-Pi uptake by $H_2O_2$ was associated with ATP depletion and direct inhibition of $Na^+$-$K^+$-ATPase activity. These results indicate that the effect of $H_2O_2$ on membrane transport function in OK cells is associated with reduction in functional $Na^+$-pump activity. In addition, the inhibitory effect of $H_2O_2$ was not associated with lipid peroxidation.

• 한국식품저장유통학회지
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• 제15권3호
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• pp.469-476
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• 2008

복숭아를 원료로 하여 항돌연변이원성이 강한 것으로 알려진 L. plantaum KLAB21 균주에 의한 젖산발효 주스의 제조 가능성과 젖산발효 특성을 조사하였다. 젖산발효에 미치는 온도의 효과를 조사한 결과 $37^{\circ}C$에서 25, 30, $40^{\circ}C$에서 보다 더욱 높은 생균수의 증가와 적정산도를 나타내었다. 살균하지 않은 복숭아 주스보다는 저온에서 살균한 주스가 젖산발효에 더욱 적합한 것으로 나타났다. 또한 L. plantaum KLAB21 균주 단독발효의 경우가 L. plantaum KLAB21 및 L. mesenteroides 두 균주의 혼합발효 경우보다 젖산발효가 큰 차이는 없었으나 다소 양호하였다. 발효시간에 따른 젖산발효 특성을 조사한 결과 발효 3일 동안에 대부분의 환원당이 소모되었으며 발효 3일 후 9.2 log cfu/mL로서 가장 높은 생균수를 나타낸 후 발효가 진행되면서 생균수는 오히려 감소하여 5일 후에는 8.4 log cfu/mL을 나타내었다. 발효 중 적정산도는 초기에 급격히 증가하였으나 점차 증가폭이 둔해졌으며 발효 5일 후의 적정산도는 1.98%이었다. pH는 발효가 진행되면서 초기 3.9에서부터 발효 5일 후에는 3.1까지 감소하였다. 발효 주스의 유기산 조성은 발효 전 복숭아 주스에서는 전혀 검출되지 않았던 젖산이 1.236.1mg%로 전체 유기산의 약 56.6%를 차지하여 가장 높았으며 발효 전 검출되지 않았던 갈락투론산은 발효 후 840.5mg%로서 전체 유기산의 38.5%를 차지하였다. 또한 92.3mg%의 사과산과 소량의 구연산 및 초산이 검출되었다. S. enterica serovar Typhimurium TA100을 사용하여 발효 주스 원심분리 상징액 $100\;{\mu}L$의 항돌연변이 활성을 조사한 결과 MNNG(N-methyl-N'-nitro-N-nitrosoguanidine)에 대하여 97.7%, NPD(4-nitro-O-phenylenediamine)에 대하여는 58.3%의 활성을 나타내었다.