• KSBB Journal
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• 제11권2호
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• pp.193-200
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• 1996

DNA를 인식하여 절단하는 제한효소의 발견은 유전자를 연구, 조작할 수 있게 되어 분자생물학 연구에 큰 발전을 가져 왔다. 제한효소의 인식자리는 반 응용액의 산도, 유기용애의 소수성에 따라서 달라질 수 있다. 제한 효소 BamHI의 특이성 변화는 유기용 매의 소수성CLogP)과 산도에 직접적인 관계가 있다. 제한효소 BamHI의 인식자리의 특이성 변화는 산도 7.5에셔 LogP값이 -1.3~-1.35, 8.0에서 -1. 0 03~-2.5, 8.5에서 0.75~-2.5, 8.9에서 -0.32 ~­2 2.5 벙위에셔 각각 나타난다. 통일한 유기용매 혼합 물에서 산도가 알카리 일수록 낮은 유기용매 놓도에 서 특이성의 변화가 나타난다. DMSO용액에서 Bam H HI의 특이성 변화는 산도가 7.5일때 20% 농도에서 나타나지만 산도가 8.9일때는 4%에서 나타난다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권1호
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• pp.66-72
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• 2010

The partitioning tracer method is to estimate the residual saturation of nonaqueous phase liquid (NAPL) in soils by analyzing tracer's retardation induced by the reversible partitioning of tracer with NAPL. This study is to estimate the residual diesel saturation in soils using the partitioning tracer method. Two-dimensional soil box was used to represent the 2-dimensional flows of groundwater and tracer solution in the saturated aquifer, and the soil box was filled with soil and then saturated with water. The residual diesel saturation was induced in saturated soil, and the partitioning tracer method was applied. The results from batch-partitioning experiment indicated that the diesel-water partitioning was linear with respect to tracer's concentration, and the partition coefficient of tracer between diesel and water was measured by their linearities. The groundwater flow in the saturated aquifer was simulated in the 2-dimensional soil box, and the residual diesel contamination was visually identified. The results from the partitioning tracer method with or without diesel in soils confirmed that 4-methyl-2-pentanol, 2-ethyl-1-butanol and 1-hexanol, can be used as a detecting method for diesel contamination. By the accuracies of estimations for diesel contamination using the partitioning tracer method, 2-ethyl-1- butanol showed the highest accuracy with 83%.

• Nuclear Engineering and Technology
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• 제31권2호
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• pp.182-191
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• 1999

The sorption of UO$_{2}$$^{2+}$ onto goethite and kaolinite under various experimental conditions was successfully interpreted using surface complexation modeling (SCM). The SCM approach used in this work is the triple-layer model (TLM) in which weakly bonded ions are modeled as outer-sphere (ion-pair) complexes and strongly bonded ions as inner-sphere (surface coordination) complexes. The change of ionic strength did not affect the U(VI) sorption onto goethite, thus the formation of inner-sphere surface complexes, (FeO)$_2$UO$_2$ and (FeO)$_2$(UO$_2$)$_3$OH$_{5}$ was assumed to simulate the effects of ionic strength and goethite concentration. On the other hand, the U(VI) sorption onto kaolinite showed ionic strength dependence, thus the formation of AlO-UO$_{2}$$^{2+}$(outer-sphere complex) and SiO(UO$_2$)$_3$OH$_{5}$ (inner-sphere complex) was assumed to simulate the experimental data. In the presence of carbonates, the sorption of U(VI) onto kaolinite decreased in the weakly alkaline pH range. This was well simulated assuming the formation of a outer-sphere surface complex, A1OH$^{2+}$- (UO$_2$)$_2$CO$_3$OH$_3$. Since SCM approach uses thermodynamic data such as surface complexation constants, it is more predictive than empirical modeling approach in which conditional values such as partition coefficient are used. used.

• Environmental Engineering Research
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• 제14권3호
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• pp.186-194
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• 2009

Understanding the environmental fate of human and animal pharmaceuticals and their risk assessment are of great importance due to their growing environmental concerns. Although there are many potential pathways for them to reach the environment, effluents from sewage treatment plants (STPs) are recognized as major point sources. In this study, the removal efficiencies of the 43 selected priority pharmaceuticals in a conventional STP were evaluated using two simple models: an equilibrium partitioning model (EPM) and STPWIN$^{TM}$ program developed by US EPA. It was expected that many pharmaceuticals are not likely to be removed by conventional activated sludge processes because of their relatively low sorption potential to suspended sludge and low biodegradability. Only a few pharmaceuticals were predicted to be easily removed by sorption or biodegradation, and hence a conventional STP may not protect the environment from the release of unwanted pharmaceuticals. However, the prediction made in this study strongly relies on sorption coefficient to suspended sludge and biodegradation half-lives, which may vary significantly depending on models. Removal efficiencies predicted using the EPM were typically higher than those predicted by STPWIN for many hydrophilic pharmaceuticals due to the difference in prediction method for sorption coefficients. Comparison with experimental organic carbon-water partition coefficients ($K_{ocs}) revealed that log KOW-based estimation used in STPWIN is likely to underestimate sorption coefficients, thus resulting low removal efficiency by sorption. Predicted values by the EPM were consistent with limited experimental data although this model does not include biodegradation processes, implying that this simple model can be very useful with reliable Koc values. Because there are not many experimental data available for priority pharmaceuticals to evaluate the model performance, it should be important to obtain reliable experimental data including sorption coefficients and biodegradation rate constants for the prediction of the fate of the selected pharmaceuticals.

• Journal of Pharmaceutical Investigation
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• 제23권3호spc1호
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• pp.41-50
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• 1993

The iontophoretic delivery across rat skin of quaternary ammonium salts (isopropamide: ISP, pyridostigmine: PS), which are positively charged over a wide pH range, was measured ill vitro. The study showed that: (a) iontophoresis significantly enhanced delivery of ISP and PS compared to respective passive transport; (b) delivery of ISP and PS was directly proportional to the applied continuous direct current density over the range of $0-0.69\;mA/cm^2;$ (c) delivery of ISP and PS was also proportional to the drug concentration in the donor compartment over the range of $0-2{\time}l0^{-2}M:$ (d) sodium ion in the donor compartment inhibited the drug transport possibly due to decreasing the electric transference number of the drug; (e) delivery of ISP and PS increased as the pH of the donor solution increased over the pH range 2-7 suggesting permselective nature of the epidermis, and inhibition of the transference number of the drugs by hydronium ion; (f) some organic anions such as taurodeoxycholate, salicylate and benzoate which form lipophilic ion-pair complexes with ISP inhibited the delivery of ISP. The degree of inhibition by the organic anions was linearly proportional to the extraction coefficient $(K_e)$ of ISP from the partition system with each counteranion between phosphate buffer (pH 7.4) and n-octanol. For PS, however, taurodeoxycholate, but not salicylate and benzoate inhibited the iontophoretic delivery. It suggests that not only sodium ion and hydronium ion but also the counteranions which form lipophilic ion-pairs with quaternary ammonium drugs are not favorable components in formulating the donor solution of the drugs to achieve an effective iontophoretic delivery.

• Journal of Pharmaceutical Investigation
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• 제33권2호
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• pp.91-97
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• 2003

During the preparation of decoction from the mixture of Coptidis Rhizoma and Scutellariae Radix, insoluble copreciptate was formed. The coprecipitated product (COP) was composed of berberine and baicalin which was the active ingredient of Coptidis Rhizoma and Scutellariae Radix, respectively. COP was slightly soluble in water and could not be well absorbed after oral administration. This poor bioavailibility might be associated with its poor aqueous solubility. With the purpose of increasing the solubility and bioavailibility of COP, hydrolysis of COP by ${\beta}-glucuronidase$ was carried out. Hydrolyzed products (HOP) of COP were identified and assayed for active ingredients. The partition coefficient study, in situ absorption test, and pharmacokinetic study after oral administration were also performed. COP was found to be consisted of berberine and baicalin with molecular ratio of 1 to 1. This compound was hydrolyzed to berberine and baicalin by ${\beta}-glucuronidase$. The rate of hydrolysis was higher at higher temperature up to $50^{\circ}C$ and higher concentration of ${\beta}-glucuronidase$ up to 2500 unit under our experimental conditions. Baicalein, which is more liphophilic than baicalin, showed greater absorption in small intestine than baicalin did. The plasma concentrations of berberine and baicalein after oral administration of HOP were significantly higer than those of COP. The possible mechanism of increased bioavailibility of berberine and baicalein could be the hydrolysis of COP by ${\beta}-glucuronidase$. On the basis of the above results, it might be said that HOP should be a suitable preparation for increasing the bioavailibility of Coptidis Rhizoma and Scutellariae Radix.

• Journal of Pharmaceutical Investigation
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• 제32권4호
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• pp.313-319
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• 2002

Rat skin permeation of various nonsteroidal antiinflammatory drugs (NSAIDs) was investigated in vitro using Franz diffusion cell at $37^{\circ}C$. The effect of various skin permeation enhancers was also observed as a preliminary study of developing transdermal delivery systems of NSAIDs. Lipophilicity of NSAIDs was determined from thε partition coefficient (log P) in 1-octanol/water and 1-octanol/IPB mutual-saturated solutions. The solubility was determined in water, isotonic phosphate buffer (IPB), and propylene glycol (PG) at $37^{\circ}C$. The rat skin permeation rate of acetaminophen, piroxicam, and aceclofenac was almost negligible, although they were saturated in PG. Addition of 1 % permeation enhancer increased the permeation rate of ketoprofen, ketorolac, and diclofenac. However, the skin permeation rate of ibuprofen did not increase with the addition of various enhancers. Among the permeation enhancers testεd, oleic acid was the most effective for various NSAIDs. Based on the daily dose, lipophilicity, and the skin permeation ratε achieved in this study, ketoprofen and ketorolac seem to be the most promising drug candidates for transdermal delivery systems, especially when formulated with unsaturated fatty acids, such as oleic acid.

• 대한환경공학회지
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• 제32권7호
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• pp.682-689
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• 2010

본 연구는 화력발전소에서 발생한 바텀애쉬와 폐타이어를 성토재로 사용하기 전 환경에 미치는 영향을 파악하기 위해 수행되었다. 바텀애쉬에 대해서는 3가지 초기 pH 4, 6, and 8 조건에서 실험하였고, 폐타이어와 바컴애쉬 폐타이어 혼합물은 pH 4 조건에서 실험하였다. 7가지 중금속 중 Pb과 Zn이 먹는물 수질기준을 초과하였으나 1 PVE안에 모두 기준을 만족하였다. 5가지 음이온 중 황산염의 농도만 기준치의 최대 10배 정도로 크게 검출이 되었으며 높은 분배계수로 인해 수질기준치 이하로 낮아지는 데 걸리는 시간도 최대 8.21 PVE에 달하였다. 혼합물의 경우 바텀애쉬와 비교 시 중금속 및 음이온의 농도를 낮추었으며 요구되는 PVE도 8.21에서 5.89로 낮추는 효과가 있었다.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.695-702
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• 2015

Liquid-liquid extraction (LLE) using various solvents was studied for recovery of acetic acid from a synthetic ethanol fermentation broth. The microbial fermentation of sugars presented in hydrolyzate gives rise to acetic acid as a byproduct. In order to obtain pure ethanol for use as a biofuel, fermentation broth should be subjected to acetic acid removal step and the recovered acetic acid can be put to industrial use. Herein, batch LLE experiments were carried out at $25^{\circ}C$ using a synthetic fermentation broth comprising $20.0g\;l^{-1}$ acetic acid and $5.0g\;l^{-1}$ ethanol. Ethyl acetate (EtOAc), tri-n-octylphosphine oxide (TOPO), tri-n-octylamine (TOA), and tri-n-alkylphosphine oxide (TAPO) were utilized as solvents, and the extraction potential of each solvent was evaluated by varying the organic phase-to-aqueous phase ratios as 0.2, 0.5, 1.0, 2.0, and 4.0. The highest acetic acid extraction yield was achieved with TAPO; however, the lowest ethanol-to-acetic acid extraction ratio was obtained using TOPO. In a single-stage batch extraction, 97.0 % and 92.4 % of acetic acid could be extracted using TAPO and TOPO when the ratio of organic-to-aqueous phases is 4:1 respectively. A higher solvent-to-feed ratio resulted in an increase in the ethanol-to-acetic acid ratio, which decreased both acetic acid purity and acetic acid extraction yield.

• 약학회지
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• 제38권2호
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• pp.123-130
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• 1994

Physicochemical properties and hydrolysis kinetics of new some oral cephalosporins were examined in buttered solution and human plasma or rat liver homogenate. The test cephalosporins were 7-[(Z)-2-(2-aminothiazole-4-yl)-2- methoxyiminoacetamido]-3-[4-(2-pyridyl)piperazinyl] thiocarbonylthhiomethyl-3-cephem-4-carboxylic acid (CEN1), 7-[(Z)-2-(2-aminoth iazole-4-yl)-2-methoxyiminoacetamido]-3-[4-(2-pyrimidyl)piperazinyl]th iocarbonylthiomethyl-3-cephem-4-carboxylic acid (CEN2), pivaloyloxymethyl-7-[ (Z)-2-(2-aminothiazole-4-yl)-2-methoxyiminoacetamido]-3-[4-(2-pyridyl)piperazi nyl]thiocarbonylthiomethy1-3-cephem-4-carboxylate (CEN1P), and pivaloyloxymethyl-7-[(Z)-2-(2-aminothiazole-4-yl)-2-methoxyiminoacetamido]-3-[ 4-(2-pyrimidyl)piperazinyl]thiocarbonyl-thiomethyl-3-cephem-4-carboxylate (CEN2P). The partition coefficient(Ko/w) of CEN1P, CEN2P were higher than those of CEN1, CEN2. The calculated pKa values of CEN1, CEN2, CEN1P, and CEN2P were 7.09, 7.75, 4.92, and 5.39, respectively. The hydrolysis of CEN1P and CEN2P were not depend on the composition of pH of the test medium except weak alkaline buffered solution (pH 8.00). CEN1 and CEN2 were very stable in pH 6.80 and 8.00 buffer solutions. CEN1P and CEN2P were rapidly deesterified to CEN1 and CEN2 in human plasma and in rat liver homogenate. Half-lives$(t_{1/2})$ of CEN1 and CEN2 were 3.49 and 4.93 hr in human plasma, 1.47 and 1.26 hr in rat liver homogenate, respectively.