• Interaction and multiscale mechanics
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• 제6권2호
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• pp.127-136
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• 2013

In this study, atomistic simulations are performed to study the effect of Al solute on the behaviour of edge dislocation in Mg alloys. After the dissociation of an Mg basal edge dislocation into two Shockley partials using molecular mechanics, the interaction between the dislocation and Al solute at different temperatures is studied using molecular dynamics. It appears from the simulations that the critical shear stress increases with the Al solute concentration. Comparing with the solute effect at T = 0 K, however, the critical shear stress at a finite temperature is lower since the kinetic energy of the atoms can help the dislocation conquer the energy barriers created by the Al atoms. The velocity of the edge dislocation decreases as the Al concentration increases when the external shear stress is relatively small regardless of temperature. The Al concentration effect on the dislocation velocity is not significant at very high shear stress level when the solute concentration is below 4.0 at%. Drag coefficient B increases with the Al concentration when the stress to temperature ratio is below 0.3 MPa/K, although the effect is more significant at low temperatures.

• 대한화학회지
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• 제34권4호
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• pp.377-383
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• 1990

용매 존재하에서 2-hydroxyethylmethacrylate와 acrylamide, N, N-dimethylamide 및 methylmethacrylate를 함량에 따라 3종류의 공중합체 수화겔막을 제조한 다음 이들 막에 알코올용질의 투과 및 분배계수를 측정하였으며, 이 측정값들을 이용하여 용질의 투과 메카니즘을 논의하였다. 수화겔막에서 유기용질의 투과계수는 그 분자의 크기에 주로 의존하였다. 그러나 수화겔막 내에 존재하는 물의 함량이 낮아지면 막에 대한 용질의 용해도가 점차 중요해짐을 또한 알 수 있었다. 분배계수의 측정 결과에 의하면 수화겔막에서의 용질의 분배는 주로 막과 용질사이에 존재하는 소수성 상호작용에 의해 조절되었다. 그리고 수화겔막에 유기용질의 확산은 전적으로 빈자리에 의존하며, 물분자와 용질 사이에 극성-편극성 및 수소결합도 부분적으로 영향을 미치나 그 정도가 아주 미약함을 확인하였다.

• 한국주조공학회지
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• 제25권1호
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• pp.36-39
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• 2005

The thermodynamic analysis of deoxidation in molten coppyr by Fe has been made. Equilibrium oxygen solubility saturated with FeO in Cu-Fe-O system has been derived without and with consideration of the solute interaction between Fe and O. The derived relationship of oxygen contents with Fe has been compared with the experimental results done by Kulkarni and the minimum oxygen solubility could be predicted by a simple first order interaction method, Wagner model.

• Archives of Pharmacal Research
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• 제12권1호
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• pp.58-61
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• 1989

Studies of selectivity of hydrogen bond formation in chiral solute-solvent systems have been performed by $^1H\;and\;^{13}C$ nuclear magnetic resonance techniques. These data are correlated with the results of gas chromatographic investigations of the same systems. Interactions between the optically active solvent(N-(N-benzoyl-L-amino acid)-anilide) and optically active solute (N-trifluoroacetyl -L-alanyl isopropyl ester) were examined. NMR evidence indicated that hydrogen bonding interaction occurred between two N-H portion and on peptidyl carbonyl portion in stationary phase and solute molecule on three points. The association constants of solvent-solute interaction were calculated and the structure of the diastereomeric association complex between N-(N-benzoyl-L-valyl)-anilide and N-TFA-L-alanyl isopropyl ester was proposed.

• Bulletin of the Korean Chemical Society
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• 제10권1호
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• pp.34-39
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• 1989

The relationship between the solute retention and physical parameters describing the interaction between the solute and mobile phase was investigated to predict the solute retention easily in RPLC. The retention data of monosubstituted benzenes were measured on the $\mu$-Bondapak C18 and phenyl columns with methanol-water systems. The linear relationship between dielectric increment($\epdilon'$) and retention data was observed. When the solute form hydrogen bonding with solvent molecules, the slope of the ln k' vs. $\epdilon'$ plot is changed as the compositions is varied. The quadric relationship between mixed solvent solubility parameter ($\delta$M) and retention data was observed.

• Membrane and Water Treatment
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• 제6권2호
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• pp.127-139
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• 2015

Rejection of ionic solutes by reverse osmosis (RO) and nanofiltration (NF) membranes is controlled mainly by electrochemical interaction as well as pore size, but it is very difficult to directly evaluate such electrochemical interaction. In this work, we used an inverse HPLC method to investigate the interaction between ionic solutes and poly (m- phenylenediaminetrimesoyl) (PPT), a polymer similar to the skin layer of polyamide RO and NF membranes. Silica gel particles coated with PPT were used as the stationary phase, and aqueous solutions of the ionic solutes were used as the mobile phase. Chromatographs obtained for the ionic solutes showed features typical of exclusion chromatographs: the ionic solutes were eluted faster than water (mobile phase), and the exclusion intensity of the ionic solute decreased with increasing solute concentration, asymptotically approaching a minimum value. The charge density of PPT was estimated to be ca. 0.007 mol/L. On the basis of minimum exclusion intensity, the exclusion distances between a salt and neutralized PPT was examined, and the following average values were obtained: 0.49 nm for 1:1 salts, 0.57 nm for 2:1 salts, 0.60 nm for 1:2 salts, and 0.66 nm for 2:2 salts. However, $NaAsO_2$ and $H_3BO_3$, which are dissolved at neutral pH in their undissociated forms, were not excluded.

• Bulletin of the Korean Chemical Society
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• 제26권8호
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• pp.1246-1250
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• 2005

We have evaluated the hydroxyl group-solvent specific interactions by using a Lichrosorb RP18 stationary phase and by measuring the retention data of carefully selected solutes in 50/50, 60/40, 70/30, 80/20, and 90/10(v/v%) methanol/water eluents at 25, 30, 35, 40, 45, and 50 ${^{\circ}C}$. The selected solutes are 3 positional isomers of phenylpropanol, that is, 1-phenyl-1-propanol, 1-phenyl-2-propanol, and 3-phenyl-1-propanol. There exist clear discrepancies in ${\Delta}H^o$ (solute transfer enthalpy from the mobile to the stationary phase) and $T{\Delta}S^o$ (solute transfer entropy) among positional isomers. The difference in ${\Delta}H^o$ and $T{\Delta}S^o$ between secondary alcohols (1-phenyl-1-propanol and 1-phenyl-2-propanol)is negligible compared to the difference between the primary alcohol (1-phenyl-3-propanol) and secondary alcohols. The $T{\Delta}S^o$ values of 3-phenyl-1-propanol are close to those of butylbenzene while the $T{\Delta}S^o$ values of secondary alcohols are close to those of propylbenzene. The difference in ${\Delta}{\Delta}H^o$ (specific solute-mobile phase interaction enthalpy) between the primary alcohol and the secondary alcohol decreases with increase of methanol content in the mobile phase. A unique observation is an extremum for 1-phenyl-3-propanol in the plot of $T{\Delta}{\Delta}S^o$ vs. methanol volume %. The positive sign of $T{\Delta}{\Delta}S^o$ of 3-phenyl-1-propanol implies that the entropy of 3-phenyl-1-propanol is greater than that of the hypothetical alkylbenzene (the same size and shape as phenylpropanol) in the mobile phase.

• Toxicological Research
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• 제23권1호
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• pp.1-9
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• 2007

Transporters are membrane proteins that mediate the transfer of substrate across the cellular membrane. In this overview, the characteristics and the toxicological relevance were discussed for various types of transporters. For drug transporters, the overview focused on ATP-binding cassette transporters and solute carrier family 21A/22A member transporters. Except for OCTN transporters and OATP transporters, drug transporters tend to have broad substrate specificity, suggesting drug-drug interaction at the level of transport processes (e.g., interaction between methotrexate and non-steroidal anti-inflammatory agents) is likely. For metal transporters, transporters for zinc, copper and multiple metals were discussed in this overview. These metal transporters have comparatively narrow substrate specificity, except for multiple metal transporters, suggesting that inter-substrate interaction at the level of transport is less likely. In contrast, the expressions of the transporters are often regulated by their substrates, suggesting cellular adaptation mechanism exists for these transporters. The drug-drug interactions in drug transporters and the cellular adaptation mechanisms for metal transporters are likely to lead to alterations in pharmacokinetics and cellular metal homeostasis, which may be linked to the development of toxicity. Therefore, the transporter-mediated alterations may have toxicological relevance.

• 대한화학회지
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• 제52권2호
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• pp.186-196
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• 2008

연구에서는 고체와 기체의 용해에 대한 대학생들의 열역학적인 이해 정도를 조사하였다. 연구 대상은 서울 지역 대학교 3학년 학생 34명이며, 용해 개념 검사지를 사용하였다. 검사지는 고체 염화나트륨과 기체 이산화탄소가 물에 용해될 때 각각의 엔탈피 변화, 엔트로피 변화, 온도에 따른 용해도 변화를 물어보는 6개의 문항으로 구성하였다. 검사지 응답을 분석한 결과 용해시 엔탈피 변화에 대한 학생들의 이해 정도는 높지 않았으며 많은 학생들이 고체 용해에 대해 용질-용매간 인력이 용질-용질간 인력보다 커야 용해가 일어난다고 생각하여 발열 과정으로 응답하였고, 또 용해가 자발적으로 일어나기 위해서는 엔탈피가 감소해야 한다고 생각하여 변화의 자발성이 엔탈피 변화에만 의존하는 것으로 생각하고 있었다. 용해시 엔트로피 변화에 대해서는 엔탈피 변화보다는 이해 정도가 높았으며 대부분 무질서도의 개념으로 이를 설명하였다. 온도에 따른 용해도 변화에 대해서는 대부분 그 방향에 대해서는 옳은 응답을 하였으나 이를 엔탈피 변화와 관련지어 설명한 학생은 25%정도밖에 되지 않았는데, 용해시 엔탈피 변화의 부호를 잘못 인식한 학생들은 올바른 설명을 할 수 없었기 때문이다.

• Membrane and Water Treatment
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• 제5권3호
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• pp.171-182
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• 2014

Organic compounds are adsorbed on RO/NF membranes, and the adsorption may influence the rejection of organic compounds by the membranes. Because almost RO/NF membranes are composite membranes, the results obtained by adsorption experiment with using membrane pieces are unable to avoid the influence by the support membrane. In this work, the interaction between membrane polymer and organic solutes was examined by an inverse HPLC methodology. Poly (m-phenylenetrimesoylate), the constituent of skin layer of RO/NF membranes, was coated on silica gel particles and used as a stationary phase for HPLC. When water was used as a mobile phase, almost hydrophilic aliphatic compounds were not effectively adsorbed on the stationary phase, although hydrophobic compounds were slightly adsorbed. The results indicated that the hydrophilic aliphatic compounds are useful probe solutes to examine the molecular sieving effect of a membrane. When water was used as a mobile phase, the aromatic compounds were strongly retained, and therefore $CH_3CN/H_2O$ (30/70) was used as a mobile phase. It was revealed that the adsorption of aromatic compounds was controlled by stacking between solute and polymer and was hindered by non-planar structure and substituents.