• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.711-712
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• 1991

• Bulletin of the Korean Chemical Society
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• 제17권11호
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• pp.975-977
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• 1996

• International Journal of Industrial Entomology and Biomaterials
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• 제23권1호
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• pp.183-186
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• 2011

The various molecular weight (MW) regenerated silk fibroins were prepared with different dissolution condition and the effect of MW on the gelation behavior of regenerated aqueous silk fibroin (SF) solution was investigated. The result of gelation time measurement indicated that the gelation of SF aqueous solution was accelerated by the increase of MW and SF concentration. When formic acid was added in SF aqueous solution, the gelation time of SFL and SFC30 aqueous solution showed a significant decreaseat 0.03% formic acid addition. In case of the lowest MW sample, SFC180, SF molecules became aggregated and precipitated without gelation after 28 days storage time. These findings indicate that MW control of SF can be utilized to control the gelation time of SF aqueous solution.

• 대한화학회지
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• 제14권1호
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• pp.91-96
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• 1970

양 이온 교환수지와 시트르산 이온($Cit^{3-}$)이 들어 있는 용액에서 방사성 $Mn^{++},\;Zn^{++}$ 및 $Co^{++}$이 수지와 용액 사이에 어떻게 분배되는가를 실온에서 조사함으로써 이들금속 이온의 시트르산 착물 형성에 관한 연구를 하였다. 용매로서 $H_2O$, 20%에탄올-$H_2O$ 및 20% 아세톤-$H_2O$를 사용하였다. 용액의 pHsms 7.0-7.4로 조절하였고 이온 강도는 약 0.10으로 유지하였다. 본 연구의 결과 $Mn^{++}$과 $Zn^{++}$은 어떤 용매계에서도 1:1 시트르산 착물[M Cit]$^-$을 형성하는 것을 알았다. 한편 $Co^{++}$은 수용액에서는 1:1 착물만을 형성하지만 위에 말한 혼합용매에서는 1:1 착물 [Co Cit]$^-$과 1:2착물 $[Co\;Cit_2]^{4-}$을 형성하는 것을 알았다. 그리고 이들 시트르산 착물이 수용액에서 보다 혼합용매 내에서 더욱 안정함을 알았다.

• 대한화학회지
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• 제17권6호
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• pp.416-423
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• 1973

양이온 교환수지(Ion Exchange Resin CGC 241)와 2염기산인 말론산 혹은 프탈산이온이 들어있는 용액에서 방사성 알칼리토류금속 이온이 수지와 용액사이에 어떻게 분배되는가를 실온에서 조사함으로써 알칼리토류금속의 유기산 착물 형성에 관한 연구를 하였다. 용매로서 H2O, 20% 에탄올-물 및 20% 아세톤-물을 사용하였고, 용액의 pH는 7.2∼7.5로 조절하였고, 이온강도는 0.10∼0.11fh 유지하였다. 본 연구결과 알칼리토류금속 이온과 말론산 및 프탈산 사이에 1:1착물이 모든 용매계에서 형성되었고 착물의 안정도는 다음순으로 증가됨을 알았다. $Ba^{++}\;<\;Sr^{++}\;<\;Ca^{++}$, 말론산 < 프탈산, 수용액 < 혼합용매

• 한국초전도ㆍ저온공학회논문지
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• 제21권1호
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• pp.40-44
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• 2019

This study investigates mixtures of water and cryoprotectant agents (CPAs) to store high-grade cold energy. Although water is an ideal material for a cold thermal storage (CTS) due to its high specific heat, undesirable volume expansion may cause structural stresses during freezing. The volume expansion can be alleviated by adding the CPAs to water. However, the CPA aqueous solutions not only have different thermal properties but also transit to amorphous state different from pure water. Therefore, these characteristics should be considered when using them as material of the CTS. In experiments, glycerol and dimethyl sulfoxide (DMSO) are selected as the candidate CPA. The volume expansion of the solution is measured by an in-situ strain gauge in low temperature region. The specific heat capacity of the solution is also measured by differential scanning calorimetry (DSC). Both the amount of volume expansion and the specific heat capacity of the CPA aqueous solution decrease in the case of higher concentration of CPA. These characteristics should be contemplated to select optimal aqueous solution for CTS for liquid air energy storage system (LAES). The CPA solutions have advantages of having wide temperature range to utilize the latent heat of water and higher sensible heat of the CPA. The CPA solutions which can satisfy the allowable stress of the structure are determined. Consequently, among the CPA solutions investigated, DMSO 20% w/w solution is the most suitable for the CTS.

• 융복합기술연구소 논문집
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• 제4권2호
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• pp.23-26
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• 2014

As an effective separation method for biomolecules, aqueous two-phase systems based on ionic liquids were suggested. Hydrophobic ionic liquids are more expensive and viscous in spite of their usage in the ionic liquid/water biphasic extraction compared with hydrophilic ionic liquids. In case of aqueous two-phase systems using hydrophilic ionic liquids, they can be diluted in aqueous phase. Experimental results show that aqueous two phase systems can be formed by adding appropriate amount of ionic liquids to aqueous salts solutions. The viscosity of ionic liquid aqueous phase is proportional to the cation chain length in ionic liquids. It is founded that the ionic liquid based aqueous two phase systems are effective for the separation of biomolecules such as acrylic acid.

• 한국환경과학회지
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• 제15권5호
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• pp.485-491
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• 2006

In the aqueous solutions the dephosphorylations of isopropyl phenyl-4-nitrophenyl phosphinate(IPNPIN) mediated by hydroxide$(OH^{\theta})$ and o-iodosobenzoate$(IB^{\theta})$ ions ate relatively slow, because of hydrophobicity of the substrate, and however it appears that $OH^{\theta}$ is inherently better nucleophile than $IB^{\theta}$, which is more soft ion. On the other hand, in cetyltrimetyiammonium bromide(CTABr) solutions which contain cationic micelles, the dephosphorylations of IPNPIN mediated by $OH^{\theta}$ or $IB^{\theta}$ ate very accelerated to 120 or 100,000 times as compared with those in the aqueous solutions. The values of pseudo first order rate constants reach a maximum with increasing. Such rate maxima are typical of micellar catalysed bimolecular reactions and the rise in rate constant followed by a gradual decrese is characteristic of reactions of hydrophobic substrates. In the cationic micellar solutions of CTABr, $IB^{\theta}$ accelerates the reactions much more than that $OH^{\theta}$ does. The reason seems that $IB^{\theta}$ which is more hydrophobic and soft ion than $OH^{\theta}$ is more easily moved into the Stern layer of the CTABr micelles than $OH^{\theta}$. In the anionic micellar solutions of sodium dodecyl sulfate(SDS), the dephosrhorylations of IPNPIN ate slower than those in aqeous solutions. It means that $OH^{\theta}$ or $IB^{\theta}$ cannot easily move and approach to the Stern layer of the micelle in which almost all the hydrophobic substrate are located and which has a negative circumstance.

• Korean Chemical Engineering Research
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• 제48권4호
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• pp.519-533
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• 2010

본 연구에서는 L-형 아미노산인 L-Alanine과 무기염인 NaCl, KCl, $NaNO_3$ 및 $KNO_3$의 각 전해질로 이루어진 L-Alanine/전해질 수용액 계에서 L-Alanine의 활동도계수와 용해도를 298.15 K에서 측정하였다. L-Alanine의 활동도계수는 양이온 및 음이온의 선택성 전극으로 이루어진 화학전지에서 두 전극간의 기전력을 측정하는 전기화학 법으로 측정하였으며, 용해도는 L-Alanine의 고체상과 상평형을 이루고 있는 포화용액을 중량 분석하여 측정하였다. 한편 본 연구에서는 아미노산(L-Alanine)/전해질 수용액 계의 잔류(residual) Helmholtz 자유에너지를 섭동사슬-통계역학적 회합성유체이론(perturbed chain-statistical associating fluid theory)과 단순-평균구근사(primitive-mean spherical approximation)이론을 결합한 관계로 모델링 하였으며, 이로부터 아미노산의 활동도계수 및 용해도에 대한 열역학적 관계식을 얻었다. Helmholtz 자유에너지를 모델링 하는 과정에서는 아미노산은 양쪽성 이온(zwitterion) 형태로 존재하며 아미노산의 양쪽성 이온은 같은 이온끼리 자기-회합(self-association)하며 동시에 물분자와 교차-회합(cross-association)하는 회합체로 가정하였으며, 또한 아미노산의 양쪽성 이온이 전해질(무기염)로부터 해리된 양이온 및 음이온과 상호작용하여 이온복합체(ion complex)를 형성하는 과정을 회합현상으로 가정하였다. 본 연구에서 제안된 이론적 모델로부터 L-Alanine/전해질 수용액 계에서 계산되는 L-Alanine의 활동도계수 및 용해도 값은 본 연구의 실험값과 일치하는 경향을 보였다.

• Journal of Pharmaceutical Investigation
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• 제34권5호
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• pp.385-391
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• 2004

The purpose of the present study was to formulate the aqueous solution of $20-O-{\beta}-D-glucopyranosyl-20(S)-protopanaxadiol\;(IH-901)$, an intestinal bacterial metabolic derivative from Ginseng protopanaxadiol saponin. For this purpose, the effects of various solubilization agents such as cosolvents [ethanol, propylene glycol (PG), polyethylene glycol 300 (PEG 300), polyethylene glycol 400 (PEG 400), glycerin], surfactants $(Tween\;80,\;Cremophor^{\circledR}\;RH40,\;Cremophor^{\circledR}\;EL,\;Poloxamer\;407,\;Poloxamer\;188)$ and a complexation agent $[hydroxypropyl-{\beta}-cyclodextrin\;(HPBCD)]$, on the solubility of IH-90l in aqueous solution were evaluated. The solubility of IH-901 in water was under $1\;{\mu}g/ml\;at\;20^{\circ}C$. Cosolvents such as ethanol, PG, PEG 300, PEG 400 and glycerin did not enhance the solubility of IH-901 at the 0 - 40% concentration range. The solubility of IH-901 was significantly elevated by the addition of cosolvents over the 80% concentration range. On the other hand, tween 80, $Cremophor^{\circledR}\;EL,\;Cremophor^{\circledR}\;RH40$ and HPBCD showed enhanced effects on the solubility of IH-901. The enhanced effects of Poloxamer 407 or Poloxamer 188 on the IH-901 solubility were less pronounced compared with $Cremophor^{\circledR}\;EL\;or\;Cremophor^{\circledR}\;RH40$. As a results, $Cremophor^{\circledR}$ aqueous solution was selected as an optimum solvent system. The aqueous solutions containing 10% $Cremophor^{\circledR}\;EL$ and 7% $Cremophor^{\circledR}\;RH40$ were formulated as dosing solutions containing 5.0 mg/ml of IH-901 for its intravenous and oral administration, respectively. The formular showed physical stability after stored for 7 days at $4^{\circ}C$.