• 한국분말재료학회지
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• 제23권4호
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• pp.311-316
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• 2016

$Ni(OH)_2$ hollow spheres have been prepared by solvent displacement crystallization using a micro-injection device, and the effect of process parameters such as concentration and the relative ratio of the injection speed of the precursor solution, which is an aqueous solution of $NiSO_4{\cdot}6H_2O$, to isopropyl alcohol of displacement solvent have been investigated. The crystal phases after NaOH treatment are in the ${\beta}-phase$ for all process parameters. A higher concentration of $NiSO_4{\cdot}6H_2O$ aqueous solution is injected by a micro-injection device and bigger $Ni(OH)_2$ hollow spheres with a narrower particle size distribution are formed. The crystallinity and hardness of the as-obtained powder are so poor that hydrothermal treatment of the as-obtained $Ni(OH)_2$ at $120^{\circ}C$ for 24 h in distilled water is performed in order to greatly improve the crystallinity. It is thought that a relative ratio of the injection speed of $NiSO_4{\cdot}6H_2O$ to that of isopropyl alcohol of at least more than 1 is preferable to synthesize Ni(OH)2 hollow spheres. It is confirmed that this solution-based process is very effective in synthesizing ceramic hollow spheres by simple adjustment of the process parameters such as the concentration and the injection speed.

• 폴리머
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• 제25권2호
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• pp.151-160
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• 2001

결정성 약제가 함침된 생분해성 고분자학이 고분자(poly(d,1-lactide)), 약제(progesterone) 및 용매(dimethylformamide)로 이루어진 고분자용액을 고형화시켜 제조되었다. 용매에 약제 및 고분자를 용해시켜 준비된 제막용액을 유리판 위에 도포한 후, 이로부터 용매를 증발시켜 고형화시키거나, 또는 고분자 및 함침 약제 모두에 비용매로 작용하는 물과 용액 필름에 존재하는 용매를 교환시켜 용액 필름이 응고되도록 하였다. 제조된 고분자막들은 용액 필름의 응고화 경로에 따라 뚜렷하게 다른 형상을 보여주었다. 진공 상태에서 용매의 증발을 통해 응고화되었을 때, 함침 약제인 프로제스테론은 구의 형상을 보여주며 고형화된 고분자 구조에 둘러싸여 막의 내부에 균일하게 분포되었다. 이에 비해, 비용매인 물에 침지시켜 용매와 비용매의 급속한 확산에 의해 응고화시키거나, 대기에 방치시켜 대기에 존재하는 수증기의 흡수에 의해 고분자 희박 지역의 핵 형성을 통한 용액 필름의 액체-액체 상분리를 유도하며 응고화시킨 경우, 함침된 약제는 고분자막 내부에 편상의 결정 구조를 지니며 막 내부에 불균일하게 분포되었다.

• 생명과학회지
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• 제6권1호
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• pp.66-71
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• 1996

동결건조한 김치를 물, 메탄올, 에칠 에테르로 각각 추출한 후 이들 용매추출물들이 지니고 있는 지질산화반응에서의 항산화력에 대하여 고찰하였다. 즉, linoleic acid mixture의 액상산화반응 조건($37^{\circ}C$)에서 과산화물 생성억제에 대한 용매별, 김치발효기간별, 농도별, 그리고 혼합용매종류별로 실험하여 추출물의 항산화능을 살펴보았다. 그 결과 물과 메탄올 추출물이 에틸에테르 추출물 보다 과산화물의 생성을 더 억제 하였다.그리고 첨가농도가 증가할수록 항산화성이 증대되었으며 발효 초일의 김치나 과숙김치보다 잘 숙성된 김치(15$^{\circ}C$에서 7일간 발효)의 추출물에 더 항산화성이 높았다. 또한 물과 메탄올의 비율을 달리 하여 추출한 경우 순수 메탄올보다 50~80% 메탄올 농도에서의 용매추출물에서 항산화효과가 높았다. 비록 75% 메탄올추출물의 항산화성은 BHA와 $\alpha$토코페롤보다는 낮았지만 동 추출물에서 계통적 분획 등에 의한 분획물의 항산화성을 계속 검토하므로서 보다 높은 항산화성 물질이 분리될 수 있음을 알 수 있었다.

• Journal of Pharmaceutical Investigation
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• 제29권4호
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• pp.329-335
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• 1999

Clenbuterol, a selective ${\beta}_2-adrenergic$ receptor stimulant, has been introduced as a potent bronchodilator for patients with bronchial asthma, chronic bronchitis and pulmonary emphysema. For the purpose of developing a transdermal preparation for clenbuterol, we attempted to select an optimal solvent system and permeation enhancer among fatty acids and fatty alcohols which are known to accelerate the penetration of various drugs in permeation experiments using hairless mouse skin and Franz diffusion cell. Apparent partition coefficient of clenbuterol was increased as pH of buffer solution was increased and solubility of clenbuterol was increased as the percent of propylene glycol(PG) in buffer solution(pH 10) was increased. Permeability of clenbuterol from different buffer(pH 10)/PG solvent mixtures was decreased as the percent of PG in pH 10 buffer solution was increased and among the various enhancers studied, lauryl alcohol was found to be the most effective enhancer, increasing the permeability of clenbuterol approximately 76-fold compared with control. Lauryl alcohol$(0{\sim}2%)$ enhanced the permeability of clenbuterol concentration-dependently. In this study, the optimal solvent system for the penetration of clenbuterol was found to be 50/50 buffer(pH 10)/PG solvent mixture containing 2% lauryl alcohol.

• Journal of Radiation Protection and Research
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• 제28권1호
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• pp.25-33
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• 2003

악성 종양 진단에 사용되고 있는 방사성 동위원소 $^{67}Ga$의 대량생산을 위한 자동화장치를 개발하였다. $^{67}Ga$은 조사된 $^{68}Zn$ 농축타켓에서 분리 생산하며 생산방법으로는 크게 용매추출법과 이온수지 법이 이용된다. 분리과정을 자동화하기 위해서 전도도 측정 장치, 화학처리 초자, 에어 공급 및 용액공급튜브, 밸브들로 이루어진 분액장치와, 이 장치를 구동하고 제어하는 PLC 기반 콘트롤러 및 사용자 직접제어용 모니터링 장치로 구성된 시스템을 개발하였다. 개발된 시스템을 사용함으로써 생산 중에 발생되는 불필요한 방사선 피폭으로부터 생산자를 보호할 뿐만 아니라, 생산시간의 단축, 생산효율의 증대로 $^{67}Ga$ 대량 생산이 가능하게 되었다.

• 한국식품과학회지
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• 제21권5호
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• pp.714-720
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• 1989

콩의 주요 저장 단백질인 glycinin의 라이신 잔기를 적당량의 acetic anhydride를 이용하여 28, 65, 85, 95%로 아세틸화시켰다. 아세틸화에 의한 구조적 변화를 solvent perturbant 방법으로 측정한 결과 자연상태의 단백질에 있어서는 타이로신 잔기의 약 40% 미만이 단백질 표면에 노출되어 있었으나 85% 아세틸화 glycinin에 있어서는 70% 이상이 표면에 노출되어 용매에 대해 접근이 용이하게 되었다. 이와 같은 현상은 second derivative spectroscopy에 의해 서로 동일하게 나타났으며, 따라서 아세틸화에 의해 타이로신과 같은 소수성 아미노산이 단백질 표면으로 이동하여 단백질 구조가 변형되었음을 알 수 있었다. 한편 near UV circular dichriosim의 결과 자연상태의 glycinin과 아세틸화가 일어난 glycinin 모두 유사한 모양의 spectra를 나타내었으나 95% 아세틸화 glycinin의 경우에는 tryptophan의 영향이 두드러졌다. Specific viscosity의 경우 아세틸화가 일어날수록 급격히 증가하였는데 이는 아세틸화에 의해 구형의 glycinin이 변형되어 분자의 부피가 커졌을 뿐 아니라 subunit의 분리에 의해 입자수가 증가했기 때문이다.

• Journal of Preventive Medicine and Public Health
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• 제27권3호
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• pp.487-504
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• 1994

A cross-sectional study was performed to evaluate the effects of chronic low-dose solvent on neurobehavioral performance of 118 male car painters. A control group of 113 workers matched for age was selected from different sections of the factory. The mean age and the mean duration of employment were 33 years and 6.7 years in both groups. Mean years of education were 11.4 years in car painters and 11.8 years in controls. Each worker completed a medical and occupational questionnaire and four tests of Swedish performance evaluation system. These included simple reaction time, symbol digit, digit span and finger tapping speed. Althougth the mean duration of employment was 6.7 years, comparison of mean performance showed a significantly poorer performance on simple reaction time (p<0.05), symbol digit(p<0.01) and digit span(p<0.05) in car painters. In univariate analysis, age and educational level contributed to poorer performance on symbol digit and digit span. Smoking appeared to slow finger tapping speed in car painters. Performance of four tests of car painters exposed to high level of solvent was poorer than that of car painters exposed to low level. In multiple regression models, controlling for age, alcohol, smoking and shift work, solvent exposure was found to be associated with performance of simple reaction time, symbol digit and digit span and exposure to high level of solvent was related to poorer performance of symbol digit and digit span.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.82-85
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• 2004

Microinterface of W/Omicroemulsion prepared by phosphatidylcholine was used as reaction media of hydrolysis of phosphatidylcholine by phospholipaseA$_2$. Phosphatidylcholine was used as an amphiphile and was acted as a substrate. Organic phase of W/Omicroemulsion in this study was prepared by mixed organic solvents i.e. 2,2,4-trimethylpentane (isooctane) as a main solvent and 1-butanol as a co-solvent. The effect of added 1-butanol was remarkable not only on reaction beginning but also on high reaction rate. The hydrolysis reaction was dramatically initiated when 1-butanol was injected into the running isooctane/PC system. The enhancement by 1-butanol addition into single organic solvent was our original finding compare with previous conventional organic solvent. The reaction rate was elevated by the added amount of 1-butanol. The enhanced reaction rate was about 150-folds. This enhancement was speculated as 1-butanol adsorption on the microinterface. The adsorbed 1-butanol improved the properties of microinterface, especially its mobility was increased by difference of the chain length between phosphatidylcholine and 1-butanol. PhospholipaseA$_2$ molecules were located on the microinterface due to modified mobility of microinterface. Located phospholipaseA$_2$ on the microinterface reacted easily with phosphatidylcholine molecule. As a result high reaction rate was obtained. Microinterfacial properties were successfully improved by adsorbed 1-butanol molecule, and were favorable to appear higher reactivity of phospholipaseA$_2$.

• KSBB Journal
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• 제26권2호
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• pp.165-171
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• 2011

Fractional solvent extraction by organic solvents such as hexane, chloroform, ethylacetate, and butanol was carried out using 70% ethanol extract of apple flower leaves. Biological activities including antioxidant, whitening, antimicrobial and anti-wrinkle activities were investigated and bio-active materials of the extracts were identified using GC/MSD. Among the tested solvent fractions, ethylacetate fraction showed the highest total polyphenol content (1218.94 ${\mu}g/mL$), and flavonoid (140 ${\mu}g/mL$). The DPPH radical scavenging activities was over 80% at a dry matterbased concentration of 200 ${\mu}g/{\mu}L$ and SOD-like activity was over 90% at 50 ${\mu}g/mL$ concentration in ethylacetate fraction that was slightly lower than of ascorbic aicd. Tyrosinase inhibition activity related to skin-whitening was over 60% by ethylacetate fraction of 100 ${\mu}g/mL$. As an anti-aging effect, elastase inhibitory activity was about 45% in ethylacetate fraction. Also, it showed a significantly antimicrobial activity against P. acenes. From GC/MSD analysis, a characteristic peak of high content in ethylacetate fraction was identified as kaempferol, which has been reported as a bioactive compound.

• 한국세라믹학회지
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• 제54권3호
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• pp.211-216
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• 2017

ZnO nanopowder was synthesized using a relatively facile and convenient glycol process. ZnO nanopowder was successfully synthesized at temperatures as low as $125^{\circ}C$ using zinc acetate as the Zn source and 1,4-butanediol as the solvent. Then, the effects of water content on the growth process and morphological evolution of ZnO powders were investigated using 1,4-butanediol and water as binary solvent mixtures. Using pure 1,4-butanediol at a temperature above $125^{\circ}C$, the prepared hexagonal ZnO nanopowder exhibited a quasi-spherical shape with average crystalline size of approximately 30 - 50 nm. It is also demonstrated that the morphology of ZnO powders can be controlled by the addition of various water content in 1,4-butanediol. With increasing water content, the morphologies of the ZnO powders changed sequentially from quasi-spherical to hexagonal plate and pyramid, and finally to hexagonal prismatic with a pyramidal tip. A sharp peak centered at 384 nm in the UV region and a weak broad peak in the visible region between 450 and 700 nm were shown in the room temperature PL spectra of the ZnO synthesized using the glycol process, regardless of the addition of water, suggesting that ZnO nanopowders with the best crystallinity were obtained under these conditions.