• 전자공학회논문지D
• /
• 제36D권9호
• /
• pp.31-36
• /
• 1999

다공질 실리콘 층을 이용한 정전용량형 알코올 센서를 제조하여 수용액 상태의 알코올(혹은 에탄올) 농도를 측정하고 그 특성을 평가하였다. 알코올 중에서 술의 주성분인 에탄올은 실리콘 웨이퍼에 대해 침투성이 강하여 수용액 내에서 실리콘 웨이퍼를 가공할 때 반응을 촉진시키는 물질로서 자주 사용된다. 본 연구에서는 각각 25와 35%의 불화수소용액에서 만든 다공질 실리콘 층을 알코올 감지막으로 한 알코올 센서를 제작하여 0%에서 100%의 알코올 농도범위에 대해 감지 특성을 측정하였다. 그 결과, 100kHz 이상의 인가 주파수에 대해 빠른 응답속도 및 선형성 뿐만 아니라 양호한 재현성이 관측되었으며, 측정된 정전용량은 수용액 속의 알코올 농도가 증가할 때 다공질 실리콘 층의 전체 유전 상수가 감소하게 되어 반비례하는 관계가 관측되었다.

• 한국재료학회지
• /
• 제13권11호
• /
• pp.725-731
• /
• 2003

The effect of organic processing parameters on the dispersion stability of the BaTiO$_3$-based dielectric particles and borosilicate glass particulate suspensions was investigated in a system where organic solvents, dispersant, binder and modifier were used as processing additives in a low temperature cofired ceramic fabrication processes. Two- and three-component organic solvents were used to disperse ceramic particles and it was found the better stability in the particulate suspension prepared in a bi-solvent, which was consists of toluene and ethanol in a non-azeotropic composition. The addition amount of organic additives had a great impact on dispersion in the present investigation. The flow curves of the suspensions prepared with binder and modifier were fitted according to the power-law equation, which indicates that the internal structure of the suspension could be disturbed under the applied shear stress. Finally, the LTCC green tapes were successfully tape-cast based upon the optimum formulation of LTCC suspension and its microstructure was compared with that of the hard-agglomerates.

• 약학회지
• /
• 제49권4호
• /
• pp.268-274
• /
• 2005

Paclitaxel is an effective antineoplastic agent against ovarian, colon and breast tumors. But there have been many difficulties to formulate this drug due to the extremely low aqueous solubility. Paclitaxel is currently formulated in a vehicle composed of Cremophor EL and absolute ethanol mixture which is $5\~20$ fold diluted in normal saline or $5\%$ dextrose solution before I.V. injection. However, this formulation has many problems such as allergic reactions and drug precipitation on aqueous dilution. To overcome these problems, we prepared the micelle and microemulsion systems for parenteral administration of paclitaxel by using glycofurol, $Soluto^{(R)}lHS$ 15 and oleic acid. Phase diagram, pH-rate stability, particle size distributions and pharmacokinetics of the systems were studied. Micelles and microemulsions formulated as nano-particle delivery system were physically and chemically stable. Therefore, these formulations might be the promising alternative candidate for the parenteral delivery of paclitaxel.

• Bulletin of the Korean Chemical Society
• /
• 제25권5호
• /
• pp.699-703
• /
• 2004

Solvolyses of isopropylsulfonyl chloride (IPSC) in water, D_2O,\;CH_3OD$, and in aqueous binary mixtures of acetone, ethanol and methanol are investigated at 25, 35 and 45$^{\circ}C$. The Grunwald-Winstein plot of first-order rate constants for the solvolytic reaction of IPSC with $Y_{Cl}$ (based on 2-adamantyl chloride) shows marked dispersions into three separate lines for three aqueous mixtures with a small slope (m < 0.30). The extended Grunwald-Winstein plots for the solvolysis of IPSC show better correlation. The kinetic solvent isotope effects determined in water and methanol are in consistent with the proposed mechanism of the general base catalyzed and/or $S_AN/S_N2$ reaction mechanism for IPSC solvolyses based on mass law and stoichiometric solvation effect studies.

• Fibers and Polymers
• /
• 제6권1호
• /
• pp.1-5
• /
• 2005

In this study, we attempted to evaluate a novel use of sericin-fixed silk fiber (SFx) as an immobilization support of enzyme. Sericin was fixed on the silk fiber using glutaraldehyde as a fixation reagent. After 6 hours of fixation, the degree of fixation increases linearly with linear decrease of the amount of bound $\alpha$-chymotrypsin (CT). This suggests that the increase of the degree of fixation is due to the further crosslinking of free aldehyde groups on the surface of sericin-fixed silk fiber (SFx). Even though perfect fixation was not achieved, sericin did not dissolve seriously and could be removed by further washing. The specific activity did not differ significantly after 6 hours of fixation. The activity of immobilized CT on SFx decreased to its half after 6 hours of incubation at 50$^{\circ}C$. However, it retained $78\%$ of initial activity even after 1 hour of treat­ment with $100\%$ ethanol. As a result, the SFx could be used as an immobilization support of enzyme in non-aqueous media at ambient temperature.

• Bulletin of the Korean Chemical Society
• /
• 제26권8호
• /
• pp.1241-1245
• /
• 2005

Solvolyses of trifluoromethanesulfonyl chloride (TFMSC) in water and in aqueous binary mixtures of acetone, ethanol and methanol are investigated at 25, 35 and 45 ${^{\circ}C}$. The Grunwald-Winstein plot of first-order rate constants for the solvolytic reaction of TFMSC with YCl (based on 2-adamantyl chloride) shows marked dispersions into three separate curves for three aqueous mixtures. The extended Grunwald-Winstein plots for the solvolysis of TFMSC show better correlation. The large negative ${\Delta}S^{\neq}$ and relatively small positive ${\Delta}H^{\neq}$ reveals that the solvolytic reaction proceeds via a typical bimolecular reaction mechanism. The l and m values determined in various solvents are consistent with the proposed mechanism of the general base catalysis $S_AN/S_N2$reaction mechanism for TFMSC solvolyses based on mass law and stoichiometric solvation effect studies.

• 생명과학회지
• /
• 제28권7호
• /
• pp.827-834
• /
• 2018

본 연구는 유용 미생물을 이용하여 흰점박이 꽃무지 유충을 발효시킨 분말을 수용성, 에탄올, 메탄올 용매별 추출하여 항산화 등의 실험에 임하였다. 발효 균주로는 3종의 유산균 Lactobacillus plantarum JBMI F3, Lactobacillus plantarum JBMI F5, Lactobacullus gasseri Ba9, 1종의 곰팡이 Aspergillus kawachii KCCM 32819, 1종의 효모 Saccharomyces cerevisiae KACC 93023, 1 종의 바실러스 Bacillus subtilis KACC 91157 총 6종의 유용 미생물 균주를 사용하였다. 발효 굼벵이 분말 추출물의 유효성분(총 페놀 함량 및 플라보노이드 함량)과 생리 활성 효능(DPPH 자유 라디칼 소거 활성, 환원력 실험, 혈전용해능, ${\alpha}-amylase$ 활성)을 비교 검토하였다. 총 페놀 함량 및 플라보노이드 함량은 바실러스 균주 발효 굼벵이 분말의 수용성 추출물에서 높은 수치를 나타내었다. 항산화 활성을 확인하기 위해 DPPH 자유 라디칼 소거능 및 환원력 실험을 수행한 결과, 비발효군 보다 발효군에서 우수한 항산화능을 보였고, 그 중 바실러스 균주를 이용한 발효 추출물이 긍정적인 효과를 나타내었다. 혈전 용해능에서 또한, 바실러스 균주 발효 굼벵이 추출물에서 우수한 혈전 용해능을 확인였고, 효소-기질 분해능 실험의 ${\alpha}-amylase$ 활성은 비발효군보다 발효군에서 높은 효과를 확인하였으나 발효균주간 유의적인 차이는 없었다. 따라서, 유용 미생물을 이용한 발효 굼벵이 추출물의 유용성분 및 생리활성이 강화됨을 확인하였고, 이는 건강 식품 소재로의 이용 가능성이 높다고 판단된다.

• 한국응용과학기술학회지
• /
• 제31권4호
• /
• pp.642-652
• /
• 2014

The synthesis of octenyl succinyl ${\beta}$-gucan (OSA-${\beta}$-glucan) was carried out and its interfacial properties at the oil-water interface and in emulsion systems were investigated. An aqueous ethanol system as a reaction media was used to facilitate the synthesis process; 10% (w/w) ethanol found to be the best as it showed a maximum degree of substitution (DS: 0.0132). FT-IR showed a characteristic absorption spectrum at $1736cm^{-1}$, indicating the esterification of octenyl succinyl groups to ${\beta}$-glucan backbone. As for interfacial tension measurements, it was decreased with increasing concentration of OSA-${\beta}$-glucan in the aqueous phase and when NaCl was added to aqueous OSA-${\beta}$-glucan solution in the range of 0.01 M to 0.1 M and also when pH was raised (pH 3 ~ pH 9). In systems of emulsion stabilized with OSA-${\beta}$-glucan, fat globule size found to decrease with increasing concentration of OSA-${\beta}$-glucan, showing a critical value of about $0.32{\mu}m$ at 0.5 wt%. When the OSA-${\beta}$-glucan emulsions were stored, it was found that fat globule size was increased with storage time and particularly pronounced increase was observed in emulsion with 1% OSA-${\beta}$-glucan, possibly due to depletion flocculation. Results of creaming stability evaluated by light scattering technique showed that it was more stable in emulsions containing smaller fat globule size. Surface load of OSA-${\beta}$-glucan in emulsions increased with increasing concentration of OSA-${\beta}$-glucan, suggesting a multilayer adsorption.

• 생명과학회지
• /
• 제17권1호
• /
• pp.51-55
• /
• 2007

갈파래(Ulva lactuca)의 용매별 분획의 항산화활성 측정을 위해 갈파래를 95% ethanol로 추출하고 diethyl ether, ethyl acetate, $H_2O$ 등의 용매로 분획하였다. 각 분획을 HPLC로 분석한 결과 각 분획에서 단일 peak가 검출되었으며 용출시간이 서로 달랐다. 각 분획의 항산화 활성을 DPPH 라디칼 소거능, 지질과산화억제활성 방법으로 검증하였다. 각 분획의 DPPH 라디칼 소거활성은 농도의존성을 나타내었고 활성은 수층, ethyl acetate 층, diethyl ether층 분획의 순서였다. 지질과산화 억제활성은 diethyl ether 분획에서 가장 높게 나타났으며 같은 농도의 $\alpha-tocopherol$과 비슷하였다. 본 연구 결과는 갈파래를 이용한 천연 항산화제 생산에 응용이 가능할 것으로 생각된다.

• 임산에너지
• /
• 제20권1호
• /
• pp.42-52
• /
• 2001

국내에 자생하는 몰푸레, 쇠몰푸레 그리고 들메나무의 수피를 채취하여 아세톤-물(7:3, v/v)로 추출한 후 동결건조시켜서 분말로 제조하였고 Sephadex LH-20 및 TSK 40F로 충진한 칼럼 상에서 메탄올, 에탄올 그리고 에탄올-헥산 혼합액을 용이용매로 상요하여 칼럼크로마토그래키를 실시하였다. 단리된 화합물들은 TLC로 확인한 후 NMR스펙트럼을 상용하여 정확한 구조규명을 하였고 FAB-MS로써 분자량을 측정하였다. 쿠마린 유도체들이 다량으로 포함되어 있었으며 소량의 ester형태의 화합물들도 단리 되었다. 물푸레와 쇠물푸레에서는 aesculetin, aesculin 및 fraxetin과 같은 쿠마린 화합물들과 ligstroside와 oleuropein과 같은 ester형태의 화합무들이 모두 단리 되었으며 들메나무에서는 ester형태의 화합물만 단리 되었다.