• Journal of Pharmaceutical Investigation
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• v.20 no.3
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• pp.153-159
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• 1990

To increase the solubility of fentiazac which is used widely as a non-steroidal antiinflammatory drug, its inclusion complex and suppositories were prepared and studied. Inclusion complexes of fentiazac with ${\beta}-cyclodertin$ $({\beta}-CyD)$ were prepared by four diffrent methods; coprecipitation method, kneading method, solvent evaporation method, freeze drying method. Suppositories of $fentiazac/{\beta}-CyD$ with PEG 1500 and Witepsol H-15 were prepared by solvent evaporation method and freeze drying method. Inclusion complex formation of fentiazac with ${\beta}-CyD$ was ascertained by powder X-ray diffractometry, differential scanning calorimetry and IR spectroscopy. The dissolution rate of fentiazac from the inclusion complex increased in distilled water and KP 2nd disintegration test fluids (pH 6.8) but extemly decreased in KP 1st disintegration test fluid (pH 1.2). Inclusion complexes prepared by freeze drying method and solvent evaporation method were similar. Freeze drying method seemed to be suitable for preparation of complex with most higher dissolution rate but coprecipitation method seemed not to be suitable. The dissolution rate of fentiazac increased markedly by ${\beta}-CyD$ complexation. The release rates of suppositories increased in the following order. Complex prepared by freeze dying method in PEG 1500 > complex prepared by solvent evaporation method in PEG 1500 > fentiazac in PEG 1500 > complex prepared by freeze dying method in Witepsol H-15 > complex prepared by solvent evaporation method in Witepsol H-15 > fentiazac in Witepsol H-15.

• Analytical Science and Technology
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• v.24 no.2
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• pp.94-104
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• 2011

Mesoporous silica was synthesized in a water solvent and in an ethanol solvent with the non and cationic cetyltrimethyl ammonium chloride (CTAC) by varying the amount of the amphiphilic acrylic urethane oligomer (AAU) and the pH of the solution. The adsorption of the MX (3-chloro-4 (dichloromethyl)-5-hydroxy-2-(5H)-furanone) in drinking water was studied using the synthesized mesoporous silica as an adsorbent. The most appropriate silica was synthesized in acidic conditions in the water solvent and in alkali conditions in the ethanol solvent. The average pore sizes of the synthesized mesosilica were 3 nm and more. The mesoporous silica synthesized by the addition of the AAU oligomer showed excellent adsorption characteristics. With respect to the co-surfactant, the best adsorption characteristics were obtained when the P64,a non-ionic surfactant with a high molecular weight, was used to synthesize the silica than when other co-surfactants were used. The adsorption rate decreased as the MX concentration in the water increased. Different adsorption equilibrium conditions were reached depending on the adsorbate MX concentration in the adsorbent and the solution. It was seen that perfect adsorption does not occur due to such equilibrium conditions.

• Resources Recycling
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• v.23 no.2
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• pp.37-45
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• 2014

Solvent extraction experiments have been performed to separate Nd and Pr from chloride leaching solution of monazite sand using single Cyanex272 and mixed extractants as PC88A+Cyanex272 and PC88A+TBP. For this purpose, the effect of the concentration of extractants on the extraction and separation of the two metals were studied by varying the pH of aqueous solution. In the experimental ranges conducted in this study, the distribution coefficients of Nd were higher than those of Pr. In Cyanex272 system, our results indicated that concentration of extractant and initial pH did not affect distribution coefficients, but separation factor was increased with increasing initial pH. In binary extractant system, distribution coefficients were lower than those of single PC88A system, whereas separation factor was similar in both mixed and single extractant system.

• KSBB Journal
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• v.11 no.2
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• pp.193-200
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• 1996

In molecular biology, type-II restriction endonuclease, which specifically recognize and cleave DNA at a limited number of sites, have been exploited as a means of characterizing DNA fragments, DNA mapping for genetic engineering. Type-II restriction endonucleases have been found to modulate their substrate specificity under modified conditions such as extreme pH, ionic strength, high enzyme concentration, substitution of metallic cofactors or addition of organic solvents. This study was initiated to investigate the modification of recognition specificity of BamHI according to the different pH and organic solvent under the given buffer condition. The specificity of BamHI is highly depends on the presence of hydrophobicity (LogP: partition coefficient) and pH of reaction solution. The specificity of BamHI is changed in range of LogP -1.03∼-1.35(at pH 7.5), -1.03∼-2.5 (at pH 8.0), -0.75∼-0.25(at pH 8.5), 0.32∼-2.5(at pH 8.9), respectively. Alteration of specificity appears in lower concentration of organic solvent when the reaction occurs in more alkali pH. For example, in DMSO solution, alteration of specificity appears in 20% concentration at pH 7.5 but in 4% concentration at pH 8.9.

• Membrane and Water Treatment
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• v.15 no.3
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• pp.117-130
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• 2024

The possibility of using lime/mineral solvent solutions has been investigated to effectively remove T-P from wastewater. The lime solvent solution showed an initial T-P removal efficiency of about 90% compared to the less efficient mineral solvent solution removal. High pH and dissolved Ca2+ can form hydroxyapatite minerals (Ca5(PO4)3(OH) or Ca10(PO4)6(OH)2 and can also remove SS and COD from wastewater. Feldspar dissolution solution can be reused twice because the Ca limited sample content provided, but further research is needed to discover other influencing parameters that control the T-P removal efficiency in real wastewater. Because it plays an important role of alkalinity in T-P removal, the success rate is limited. In practical applications, it is obtained according to the pH value wastewater in the environment. The results obtained in this study can highlight new insights on the use of limestone/dissolved mineral solutions to control T-P in wastewater, instead of directly using commercial chemical agents that can produce large amounts of unreacted chemical sludge.

• Bulletin of the Korean Chemical Society
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• v.13 no.6
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• pp.642-647
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• 1992

Second-order rate constants have been measured spectrophotometrically for the reactions of substituted phenyl acetates with butane-2,3-dione monoximate and p-chlorophenoxide anions in MeCN-H$_2$O mixtures of varying compositions. The reaction rate, unexpectedly, decreased remarkably upon initial additions of MeCN to H$_2$O up to 30-40 mole ${\%}$ MeCN, and followed by a gradual increase upon further additions of MeCN. The change in solvent composition also influenced the magnitude of the ${\alpha}$-effect, i.e., the ${\alpha}$-effect increased as the mole ${\%}$ MeCN increased. The solvent dependent ${\alpha}$-effect for the present system appears to indicate that the differential solvation between the ${\alpha}$-effect nucleophile and the corresponding normal nucleophile is not solely responsible but the difference in the transition-state stabilization is also responsible for the ${\alpha}$ -effect in organic solvent-rich region.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.353-356
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• 2001

The relation between the flocculation and dispersion of metal oxide powders and the properties of solvents, such as dielectric constant and solubility parameter, was investigated for TiO$_2$, $Al_2$O$_3$and Fe$_2$O$_3$particles. The particle size and median diameter of these metal oxides were measured in many organic solvents, from which the effect of solvents on the flocculation and dispersion of metal oxide powders was considered. The metal oxide powders of TiO$_2$, $Al_2$O$_3$and Fe$_2$O$_3$tend to disperse in a solvent of higher polarity, whereas they are apt to flocculate in a solvent of low dielectric constant, because the Hamaker constant between the particles becomes larger in such a solvent. There we, however, some solvents that do not obey these tendencies. It is possible to evaluate the flocculation and dispersion of these metal oxide powders in many solvents by using numeral balances of Hansen’s three-dimensional solubility parameter (f$_{d}$, f$_{p}$ and f$_{h}$). There exists a solvent giving the optimal dispersion for each metal oxide, and the optimal dispersion point of f$_{d}$, f$_{p}$ and f$_{h}$ is determined by the combination of various metal oxide powders and solvents.nts.nts.nts.

• Journal of the Korean Wood Science and Technology
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• v.41 no.5
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• pp.447-455
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• 2013

Hemicellulose extract obtained by pre-pulping extraction of woodchips, is very diluted acidic in nature. The major component responsible for this weak acidity is acetic acid, present in levels up to 5~10 g/L. Here, we report an exploratory study on the extract upgrading by reactive solvent extraction of acetic acid as well as ASPEN simulation. In this study, liquid-liquid equilibria for the ternary systems (water + acetic acid + ethyl acetate) were measured at the temperature of 298.15 K and 10 (pH = 2.02), 5 (pH = 2.17), and 1 (pH = 2.48) percent of acetic acid samples were used to carry out liquid-liquid extraction studies using ethyl acetate. In a one-stage batch experiment, 96.0% of acetic acid could be extracted for the solvent when the ratio of organic-to-aqueous phases is 4:1. For simulation results, they were used to estimate the interaction parameters between each of the three compounds of the systems studied for the NRTL and UNIQUAC models. The estimated interaction parameters were successfully used to predict the equilibrium compositions by the two models.

• Textile Coloration and Finishing
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• v.15 no.3
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• pp.146-153
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• 2003

This article describes the metal ions adsorption of chitosan fibers. The chitosan fibers were manufactured by wet spinning using 2% acetic acid as solvent, 10% aqueous sodium hydroxide as non solvent, and 4%chitosan solution as a solvent. The adsorption characteristics of chitosan fibers towards 100ppm solutions of various metal ions such as Cu(II), Cd(II), Cr(III), Hg(II) were examined at different pH value by ICP-Atomic Emission Spectrometer. The adhesiveness of metallic ions to the chitosan fiber were increased with the increase of pH and the decrease of denier. On the other hand, from pH4, chitosan fiber that is immersed in metal ion aqueous solution of Cu(II) and Cd(II) became homogeneous solution because is dissolved. The adhesiveness of metallic ions to chitosan fiber were found to increased in a sequence of Hg(II)> Cr(III)> Cu(II)> Cd(II). The antimicrobial characteristics of the chitosan fiber by adhered metal ions, virgin chitosan fiber, and cotton fiber were evaluated. The antimicrobial activity of the fibers were increased with the decrease of denier.

• Bulletin of the Korean Chemical Society
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• v.19 no.1
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• pp.50-56
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• 1998

A solvent sublation was studied for the determination of trace Cd, Co, Cu and Ni in water samples. Ammonium pyrrolidine dithiocarbamate (APDC) was used as a complexing agent. Experimental conditions such as pH of solution, amounts of APDC, the type and amount of surfactant, the type of solvent, etc. were optimized for the effective sublation of analytes. After metal-PDC complexes were formed in sample solutions of pH 2.5, the precipitate-type complexes were floated in a flotation cell with an aid of sodium lauryl sulfate as a surfactant and by bubbling with nitrogen gas. The precipitates were dissolved and separated into the surface layer of methyl iso-butyl ketone (MIBK). The analytes preconcentrated were determined by a graphite furnace atomic absorption spectrophotometry (GF-AAS). Extractability of each element was 88% for Cd(Ⅱ), 86% for Co(Ⅱ), 95% for Cu(Ⅱ) and 76% for Ni(Ⅱ), respectively. And this procedure was applied to the analysis of real samples. From the recoveries of more than 92%, it was concluded that this method could be simple and applicable for the determination of trace elements in various water samples of a large volume.