• Archives of Pharmacal Research
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• 제23권4호
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• pp.385-390
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• 2000

To demonstrate the effect of formulation conditions on the controlled release of protein from poly(lactide-co-glycolide) (PLGA) microspheres for use as a parenteral drug carrier, ovalbumin (OVA) microspheres were prepared using the W/O/W multiple emulsion solvent evaporation and extraction method. Methylene chloride or ethyl acetate was applied as an organic phase and poly(vinyl alcohol) as a secondary emulsion stabilizer. Low loading efficiencies of less than 20％ were observed and the in vitro release of OVA showed a burst effect in all batches of different microspheres, followed by a gradual release over the next 6 weeks. Formulation processes affected the size and morphology, drug content, and the controlled release of OVA from PLGA microspheres.

• Journal of Photoscience
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• 제11권3호
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• pp.95-99
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• 2004

Optical absorption and emission studies have been carried out to understand the effect of deuterium on the solvent dependent photophysical properties of curcumin in deuterated solvents such as $CDCl_3,\;(CD_3)_2SO,\;(CD_3)_2CO,\;CD_3OD\;and\;CD_3CN$. Optical absorption spectral studies showed that there is no significant shift in absorption maxima compared to the non-deuterated solvent. The fluorescence maxima shows significant shift with polarity of solvent but not much affected by the deuteration. The fluorescence quantum yield of curcumin increased marginally in almost all the deuterated solvents, indicating reduction in the non-radiative pathways. The fluorescence decay was biexponential in all the solvents and the average fluorescence lifetime was not much affected with deuteration, but showed decrease with increasing solvent polarity. Based on these studies, it is concluded that intermolecular hydrogen transfer is only partially responsible for the excited state deactivation of curcumin.

• Bulletin of the Korean Chemical Society
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• 제22권8호
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• pp.877-882
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• 2001

The solvent effects on the relative free energies of Eu3+ to Yb3+ ion mutation in solution have been investigated using a Monte Carlo simulation of statistical perturbation theory (SPT). Our results agree well with available data that were obtained by others. Particularly, the results of water (SPC/E) solvent are almost identical with experimental data. For the present Eu3+ and Yb3+ ions, the relative free energies of solvation vs. Born’s function of bulk solvents decrease with increasing Born’s function of bulk solvents. There is also good agreement between the calculated structural properties in this study and the published works obtained by computer simulation and experimental work.

• 한국미생물·생명공학회지
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• 제28권1호
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• pp.26-32
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• 2000

Electrostatic forces contribute to the high degree of enzyme transition state complementarity in enzyme catalyzed reaction and such forces are modified by the solvent through its dielectric constant and polar properties. The contributions of electrostatic interaction to the formation of ES complex and the stabilization of transition state of the trypsin catalyzed reaction were probed by kinetic studied with high pressure and solvent dielectric constant. A good correlation has been observed between the increase of catalytic efficiency of trypsin and the decrease of solvent dielectric constant. Activation volume linearly decreased as the dielectric constant of solvent decreased, which means the increase in the reaction rae. Moreover, the decrease of activation volume by lowering the solvent dielectric constant implies a solvent penetration of the active with and a reduction of electrostatic energy for the formation of dipole of the active site oxyanion hole. When the 야electric constant of the solvents was lowered to 4.7 unit, the loss of activation energy and that of free energy of activation were 2.262 KJ/mol and 3.169 KJ/mol, respectively. The results of this study indicate that the high pressure kinetics combined with solvent effects can provide unique information on enzyme reaction mechanisms, and the controlling the solvent dielectric constant can stabilize the transition state of the trypsin-catalyzed reaction.

• 한국응용과학기술학회지
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• 제38권1호
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• pp.292-299
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• 2021

본 연구에서는 해삼속의 폴리페놀과 플라보노이드의 생리활성물질을 추출하기 위한 용매분획의 수율을 확인하고자 연구를 시도하였다. 이미 보고된 사례에서 50%에탄올 추출 용매분획은 해삼 항산화 물질의 높은 수율 결과로 확인되었다. 해삼의 항산화물질 추출량을 결정짓는 것은 추출에 적용된 추출 용매분획의 결과로 확인되었다. 또한 '추출용매에 따라 해삼생리활성 항산화물질 추출함량이 크게 차이가 있다.'는 선행연구를 통해 용매분획추출에 관한 필요성의 결과를 얻었다. 50%에탄올 추출 용매분획의 해삼추출물에 포함된 페놀물질의 높은 항산화성분 추출 결과가 증명되었다. 추출용매분획 연구사례에서 수율이 가장 저조한 아세트산에틸 용매분획은 다른 용매분획에 비해 높은 페놀함량을 수확하여 항산화효과가 확인되었다. 이에, 추출 용매분획물의 적용에 따른 수율변화를 통해 항산화추출물의 높은 수율에 미치는 영향을 확인 하였다. 따라서 본 연구를 통해 50%에탄올 용매의 최적화된 해삼생리활성물질 추출 용매분획으로 검증되었다.

• 폴리머
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• 제26권3호
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• pp.307-315
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• 2002

폴리스티렌의 취약한 성질을 개선한 내충격정 폴리스티렌 (HIPS)의 내충격성에 영향을 주는 요소는 분산된 고무상 입자의 크기 및 입도분포, 분자량, 형태구조, 그래프트율 등이다. 이에 따라 HIPS의 물성은 영향을 받으므로 이를 조절하거나 파악하는 것은 중요하다. 본 연구에서는 HIPS의 벌크-용액중합에서 용매함량이 고무입자의 형태구조 및 입도분포, 최종 물성에 미치는 영향에 대하여 고찰하였다. 먼저 중합 진행에 따른 분산상의 입도분포를 측정함으로써 상역전 현상의 변화 추이를 파악하여 전중합 시간을 결정하였다. 중합시 분산용매는 적절한 양에 도달하기 전까지는 고무입자의 크기가 증가하였으며, 그 후에는 점차적으로 감소하였다. 고무상의 형태구조는 분산용매가 증가함에 따라서 그래프트율이 증가하는 형태구조로 바뀌는 것으로 사료된다. 분산용매가 첨가됨에 따라 유변물성 및 인장물성이 취약해졌는데, 이는 분산용매에 의한 사슬이동반응이 매트릭스상인 폴리스티렌의 분자량을 감소시킨 점과 잔류 용매의 존재 때문이었다. 하지만 내충격성은 분산입자의 크기가 증가한 경우 향상되는 경향을 보였다.

• Asian Journal of Atmospheric Environment
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• 제11권1호
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• pp.1-14
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• 2017

For the quantitative analysis of volatile organic compounds (VOC), the use of a proper solvent is crucial to reduce the chance of biased results or effect of interference either in direct analysis by a gas chromatograph (GC) or with thermal desorption analysis due to matrix effects, e.g., the existence of a broad solvent peak tailing that overlaps early eluters. In this work, the relative performance of different solvents has been evaluated using standards containing 19 VOCs in three different solvents (methanol, pentane, and hexane). Comparison of the response factor of the detected VOCs confirms their means for methanol and hexane higher than that of pentane by 84% and 27%, respectively. In light of the solvent vapor pressure at the initial GC column temperature ($35^{\circ}C$), the enhanced sensitivity in methanol suggests the potential role of solvent vapor expansion in the hot injector (split ON) which leads to solvent trapping on the column. In contrast, if the recurrent relationships between homologues were evaluated using an effective carbon number (ECN) additivity approach, the comparability assessed in terms of percent difference improved on the order of methanol (26.5%), hexane (6.73%), and pentane (5.24%). As such, the relative performance of GC can be affected considerably in the direct injection-based analysis of VOC due to the selection of solvent.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1992년도 학술발표회 초록집
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• pp.113-114
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• 1992

• Bulletin of the Korean Chemical Society
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• 제22권12호
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• pp.1301-1302
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• 2001

• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1127-1130
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• 2009

The effects of different dihydroxybenzoic acid (DHB) isomers, when used as matrix materials in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), were investigated in analyses of polyethylene glycol (PEG) polymers. PEG polymers ranging from 400 to 8,000 Da were prepared in different DHB isomer matrices using solvent-based and solvent-free methods. PEG samples were detected only in matrices of 2,3-DHB, 2,5-DHB, and 2,6-DHB while the most intense peaks were observed using 2,6-DHB in both solvent-free and solvent-based preparations.