• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.581-587
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• 2005

In order to obtain a highly purified p-dioxanone (PDX) as monomer of biodegradable polymer, suitable solvent must be selected. The selection was based on the solubility of impurities, and partial layer melt crystallization were carried out under the presence of solvent. The solubility of PDX in various solvents such as ethyl acetate, tetrahydrofuran, acetone, alcohols (methanol, ethanol, 1-propanol, 1-butanol and 1-pentanol) were measured over the temperature range of $-10{\sim}15^{\circ}C$. As solubility parameters, the mixing and dissolution enthalpy between the PDX and the solvents was studied based on empirical equations and the regular solution theory. The solubility and the temperature dependency of the solubility with the solvents of acetone, ethylacetate, and tetrahydrofuran of PDX were shown to have relatively high values compared to the alcohol type solvents. Also, in same alcohols, the smaller molecules and higher polarity gave higher solvency. In partial layer melt crystallization, small amount of ethylacetate selectively dissolved impurities and gave highly purified p-dioxanone, over 99.9% purity.

• Food Engineering Progress
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• v.15 no.2
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• pp.175-181
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• 2011

By using supercritical carbon dioxide fluid, an attempt was made to extract surface-active substances from defatted rice bran. Extraction was carried out according to D-optimal design and results were analyzed by response surface methodology to establish optimum condition. It was found that pressure, temperature and co-solvent (ethanol) influenced in a different extent on the extraction efficiency (i.e., yield and interfacial tension) of surface-active substances. Among them, co-solvent was found to be a major influencing factor, where maximum yield (2.62%) was observed at the highest content (250 g). In addition, it also affected most on the interfacial tension at the oil-water interface but in this case the lowest interfacial tension value (9.51 mN/m) was found when added lowest (50 g). In conclusion, it was estimated that the optimum extraction condition was to be pressure 350bar, temperature $62^{\circ}C$ and co-solvent content 50 g in this study, where extraction yield was 0.69% and interfacial tension to be 10.1 mN/m.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1635-1641
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• 2011

This study was designed to investigate antioxidant activities of pomegranate endocarp extracts. Pomegranate endocarp extract contains the highest antioxidant function compared to pomegranate extracts from other parts. Pomegranate endocarp extract was fractionated with hexane, dichloromethane, ethyl acetate, butanol extract, and water, followed by evaluation for antioxidant activity. During this experiment, various antioxidant tests such as nitrite scavenging activity, reducing power, superoxide anion scavenging activity, $ABTS^+$ scavenging activity, SOD like-activity, and DPPH radical scavenging activity were conducted on the $CH_2Cl_2$, EtOAc, BuOH, $H_2O$ fractions of pomegranate endocarp extract. Results showed that the ethyl acetate fraction contained the highest DPPH radical scavenging activity among the samples. For SOD like-activity, the dichloromethane fraction had the highest antioxidant activity. For superoxide anion scavenging activity, the ethyl acetate fraction had the highest antioxidant activity. In the $ABTS^+$ scavenging activity test, the ethyl acetate fraction $IC_{50}$ was 39.26 ${\mu}g$/mL, whereas that of the butanol fraction was 40.95 ${\mu}g$/mL. In testing reduction power at 0.1 mg/mL, the O.D. of the ethyl acetate fraction was highest at 1.404 and showed higher activity than ascorbic acid at 1.332. The results of the nitrite scavenging activity test were very similar to those of the SOD like-activity test. These results suggest that pomegranate endocarp extract may have value as a natural antioxidant.

• Journal of Life Science
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• v.22 no.7
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• pp.958-963
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• 2012

The antioxidant activities of 6 solvent extracts of Artemisia capillaris were evaluated in a dintroflurobenzen (DNFB)-induced allergic mouse model. In vitro antioxidant activities were determined using DPPH and the FRAP test. Methanol (DPPH: 85.87%, FRAP: 1.772) and $dH_2O$ (DPPH: 60.69%, FRAP: 3.185) extracts showed the highest antioxidant activities compared with other solvents (ethyl acetate 41.81%, 0.407, hexane 8.37%, 0.328, etc.). In addition, we tested atopic dermatitis (AD)-like skin lesions in mice treated with DNFB. The methanol extract of A. capillaris on the AD-like skin lesions in DNFB-induced atopy inhibited ear thickness increases (47%) and the skin lesions (45%) compared with a positive control (methanol). The results suggest that they have potential as natural antioxidants and allergy-improving substances and that they may be valuable materials in the functional food or cosmeceutical industry.

• Elastomers and Composites
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• v.46 no.4
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• pp.295-303
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• 2011

A series of new aromatic polyhydroxyamides (PHAs) containing imide ring were prepared by direct polycondensation reaction of imide-diacids and two types of bis(o-aminophenol)s including 3,3'-dihydroxybenzidine and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. The polymers were characterized by FT-IR, FT-NMR, DSC and TGA. The inherent viscosities of the PHAs measured at $35^{\circ}C$ in DMAC solution were in the range of 0.49-1.13 dL/g. PHA 2 and 3, except PHA 1, were soluble in polar solvents such as DMAc, DMF and NMP. PHA 4, 5, and 6 containing 6F group showed a higher solubility in less polar solvents. But the polybenzoxazoles (PBOs,) were insoluble in a variety of solvents except partially soluble in sulfuric acid. The PBO 1, 2 and 3 showed maximum weight loss temperature in the range of $650-656^{\circ}C$ and relatively high char yields in the range of 57.4-61.9 % under a nitrogen atmosphere. These results suggested that the introduction of imide or diimide ring in the main chain was effective in improving the thermal stability of PHAs and PBOs.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.555-560
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• 2008

Extraction was performed to prepare ash-free coal from low rank coal under the temperature of $200-430^{\circ}C$ and initial pressure of 0.1MPa. Three kinds of coal samples with different rank were used and N-methyl-2-pyrrolidinone(NMP, polar), 1-methyl naphthalene(I-MN, non-polar), Light Cycle Oil(LCO, non-polar) were used as solvents. Results showed that higher extraction yield could be obtained with NMP than with 1-MN and LCO, but the ash concentration shows minimun in the case of 1-MN. Three operation modes were compared, that is, idle, agitation and ultrasonic extraction mode. From the results, it was found that the extraction yield and ash concentration were 70.09% and 1.03% under the agitation mode, 80.7% and 0.76% under the ultrasonic operation mode respectively in the case of NMP used at the temperature of $350^{\circ}C$. Similar results were obtained with 1-MN. Effect of ultrasonic on the extraction was estimated as 15-20% increase in the yields and 26% reduction in the ash concentration.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1156-1163
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• 1996

This study is related to the investigation of the characteristics of quaternary ammonium salt catalyst on the addition reaction of carbon dioxide and glycidyl methacrylate(GMA) to form(2-oxo-1,3-dioxolane-4-yl)methacrylate(DOMA). Among the salts tested, the ones with higher alkyl chain length and with more nucleophilic counter anion showed a higher catalytic activity. Mixed catalysts of NaI and 18-crown-6 showed a good yield of DOMA, but when they are used alone, they showed no catalytic activity. The DOMA monomer was obtained in low polar solvents, while poly(DOMA) could be directly synthesized in aprotic dipolar solvents. Kinetic studies carried out by measuring $CO_2$ pressure in a high pressure batch reactor showed that the reaction rate was first order to the concentration of GMA and $CO_2$ respectively. The rate constant(k) was 0.56L/mol hr and Henry's constant(H') of $CO_2$ in diglyme at $80^{\circ}C$ was $6.5{\times}10^{-4}mol/L{\cdot}kPa$.

• Journal of the Korean Chemical Society
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• v.31 no.1
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• pp.55-63
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• 1987

The systematic investigation of the retention behaviors of 18 monosubstituted benzenes in reversed-phase liquid chromatography(RPLC) was studied in order to predict the separation possibility of their mixtures and study the contribution of substituent group to the retentions of solutes. The columns and mobile phases employed in this study were $\mu$ -Bondapak $C_{18}$, $\mu$-Bondapak phenyl columns and methanol/water, acetonitrile/water, and THF/water, respectively. The polar substituents such as phenol, aniline, acetophenone and benzonitrile have smaller capacity factor(k') values than benzene, while nonpolar ones such as alkylbenzenes and halobenzenes show larger k' value. The capacity factors of all solutes increased on both C18 bonded and phenyl bonded phases as the organic solvent content of three organic solvent-water mixtures decreased. The absolute differences in capacity factor(${\Delta}k$') between substituent and benzene were graphically shown for the prediction of the separation of the mixture and interpretation of the elution behavior of substituent. In addition, the selectivity of solvent system for the separation of the mixture was investigated in both two columns and three mobile phases.

• Korean Journal of Medicinal Crop Science
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• v.4 no.1
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• pp.31-37
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• 1996

This study was conducted to know the odor characteristics and compounds in neutral, acidic and basic fraction from the essential oil of Valerliana fauriei root. Among the fraction from the essential oil of V. fauriei root, the content of neutral fraction was 92%, that of the acidic fraction, 6%, and that of basic and phenolic fractions, less than 1%, respectively. The neutral fraction was characterized by sweet-balsamic, woody, musky and medicinal odor. The acidic fraction had sweat-socks, valeric-like and cheese-like odor characters. The netural fraction of essential oil was fractionated by solvents with different polarities, resulting in 44% of ethyl ether fraction, 34% of pentane-ethyl ether fraction, 11% of pentane fraction and 11% of methanol fraction. The ethyl ether fraction was characterized by woody and medicinal odor and the pentane-ethyl ether fraction, by sweet-balsamic, woody and herb-like odor. The fractions were fractionated again by different solvents, and 12 chemical components including valeranone, 26 components including bornyl acetate, and 43 components including camphene were identified in the ethyl ether fraction, the pentane - ethyl ether fraction, and pentane fraction, respectively. In the acidic fraction, n-butanoic acid and other 44 components were identified, among which the most abundant ones were 3-methyl butanoic acid(42.1%), dimethoxy-2-propanoic acid(11.5%), and 5-­ethyldihydro-2H-furanone(5.7%).

• Food Science and Preservation
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• v.9 no.1
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• pp.97-101
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• 2002

Antimicrobial and antioxidative activities of various solvent extracts from different parts of the loquat were investigated to process it as the functional food. The extraction yield showed higher in butanol fraction of 4.95% in peel and 4.42% in seed than others, but water fraction showed high extraction yield of 3.89% in leafs 23.6% in the seedless fruit and 21.1% in fresh, In the antimicrobial activity test, ethyl acetate fraction that leaf and fruit excluded seed inhibited higher 19, 15 mm and 16, 15 m in clear zone far Staphylococcus aureus and Escherichia coli in each. Ethyl acetate fraction that extracted from a series of polar and nonpolar solvent fractionation of methanol extracts showed better results in the hydrogen donating activity of 82% in leaf, 74% in seedless fruit, 68% in seed, 52% in peel and 30% in fresh.