• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.807-815
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• 2017

This study investigated the removal efficiency of residual pentane from paclitaxel according to the drying temperature in the case of rotary evaporation, and performed a kinetic and thermodynamic analysis of the drying process. At all the temperatures (25, 30, 35, 40, and $45^{\circ}C$), a large amount of the residual solvent was initially removed during the drying, and the drying efficiency increased when increasing the drying temperature. Five drying models (Newton, Page, modified Page, Henderson and Pabis, Geometric) were then used for the kinetic analysis, where the Henderson and Pabis model showed the highest coefficient of determination ($r^2$) and lowest root mean square deviation (RMSD), indicating that these models were the most suitable. Furthermore, in the thermodynamic analysis of the rotary evaporation, the activation energy ($E_a$) was 4.9815 kJ/mol and the standard Gibbs free energy change (${\Delta}G^0$) was negative, whereas the standard enthalpy change (${\Delta}H^0$) and standard entropy change (${\Delta}S^0$) were both positive, indicating that the drying process was spontaneous, endothermic, and irreversible.

• Elastomers and Composites
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• v.40 no.4
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• pp.277-283
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• 2005

LV transition curves for poly(ethylene-co-15.3 mol% octene) ($PEO_{15}$) and poly(ethylene- co-17.0 mol% octene) ($PEO_{17}$) were measured in cyclo-pentane and cyclo-hexane. Between $40{\sim}150^{\circ}C$, the LV curve for ($PEO_{15}$ + cyclo pentane) located $1.1{\sim}2.7$ bar higher than that for ($PEO_{17}$+ cyclo-pentane). In cyclo-hexane, similar behavior was observed for $PEO_{15}$ and $PEO_{17}$ solution except the pressure difference reduced to $0.9{\sim}l.6$ bar. If the backbone structure of $PEO_{15}$ were identical to that of $PEO_{17}$, the LV line for $PEO_{17}$ would locate at high pressures than that for $PEO_{15}$, since the number average molecular weight of $PEO_{17}$ (Ave. Mn=153,040) is 1.9 times higher 4han that of $PEO_{15}$ (Ave. Mn=82,200). The difference in the octene comonomer content between $PEO_{15}$ and $PEO_{17}$ is only 1.7 mole%, nevertheless this small difference in the backbone structure of the PEO greatly affected the location of the L-V curves in the mixtures comprised of PEO and cyclo-alkane.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2004.10a
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• pp.444-449
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• 2004

• Bulletin of the Korean Chemical Society
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• v.26 no.2
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• pp.292-296
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• 2005

Physical and chemical properties of thexylboronic acid and its derivatives such as thexylboroxine and ethylene glycol or diethanolamine thexylboronic ester have been studied. Thexylboronic acid can be extracted from an organic solution with an aqueous sodium hydroxide solution as an “te”complex. It is readily converted into thexylboroxine in the presence of anhydrous magnesium sulfate in pentane. It reacts with simple alcohols only slowly; however, it reacts readily with excess diethanolamine in the presence of anhydrous magnesium sulfate to give the corresponding ester.

• Archives of Pharmacal Research
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• v.18 no.1
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• pp.51-55
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• 1995

A facile convenient syntheses of the titled compounds, via reacting the precusor 2-amino-2-(pentane-2, 4-dion-3-yithio)-6-phenylpyrimidine-5-carbonitrile (1) with nitrogen nucleophiles and with the carbanions of some active methylene compounds, is reported. Chemical and spectroscopic evidence of the newly syntheised compounds are described.

• Membrane Journal
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• v.10 no.1
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• pp.19-29
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• 2000

To estimatc mutual diffusion coefficient for the analysis of mass transfer phenomena in polymer/solvent system, two models are proposed and the equations are derived. The estimates of mutual diffusion coefficients are obtained by two models suggested in this work and compared with and experimental data and Vrentas-Duda's. Vrentas-Duda's self diffusion coefficient was used for the mutual diffusion coefficient. Derivative of chemical potential on solvent was derived and used using original UNIFAC-FV and modified UNIFAC-FV. However, Vrentas-Duda's equation for mutual diffusion coefficient contains Flory-Huggins parameter x. For the derivative of chemical potential term, Vrentas-Duda assumed that parameter x was constant and independent of temperatures and concentrations The assumption is one of shortcoming in vrentas-Duda's mutual diffusion coefficient. New methods proposed in this work do not have such assumptions and simplifications. For the solvent of cyclohexane, n-pentane, and n-hexane in PIB(polyisolbutylene) and PMS-BR (poly(p-methylstyrene-co-isobutylene), new methods well correlate the experimental data at various temperatures and concentrations, and predicted the experimental data much better than Vrentas-Duda's for the PIB/toluene system. It is shown that new methods are excellent tools for correlating mutual diffusion coefficient data in polymer/solvent system over wide ranges of temperature and concentration without any assumptions or simplifications.

• Korean Journal of Food Science and Technology
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• v.25 no.1
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• pp.52-56
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• 1993

Flavor compounds formed in the ramyon fried in palm oil at $148-150^{\circ}C$ for 1 minute during storage at $65^{\circ}C$ were isolated and identified by gas chromatography-mass spectrometry. Their changes in the amount when the ramyon was stored at 20, 40 and $65^{\circ}C$ were also studied by using static headspace gas chromatography. Pentane, hexane, butanal, heptane, 1-pentanol, hexanal, and octane were formed during $65^{\circ}C$ storage of the ramyon and they were thought to be from linoleic and oleic acid present in ramyon. Formation of the flavor compounds was shown to increase with the storage temperature and/or storage time. Hexanal showed the highest correlation with the sensory score(r=0.87).

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.579-587
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• 1992

It was explored, whether the usual course of the ozonolysis of olefins can be modified with the help of pyridine. In the First step, the ozone oxidation of trans-3-hexene was performed with and without pyridine in the inert solvents n-pentane and dichloromethane. In addition, base catalyzed decompositions of monomeric and polymeric ozonides were also examined to identify the reaction mechanism. The reaction products were identified by modern analytical tools. The results of this work showed that reactions of ozone with olefins in the absence of pyridine in aprotic solvents gave, one hand, dominantly peroxidic products, namely monomeric and polymeric ozonides. The other hand, they in the presence of pyridine gave only the non-peroxidic products, namely propionaldehyde and rearranged propionic acid without peroxidic products. It seems, also, that the pyridine-catalyzed isomerization of the Criegee zwitterion of trans-3-hexene to give propionic acid takes place in the ozone oxidation of trans-3-hexene.

• The Korean Journal of Food And Nutrition
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• v.14 no.1
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• pp.15-19
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• 2001

An attempt was made in this study to analyze volatile flavor components of A. macrocephala Koidz. and A. lanacea DC. (Atractylodes japonica Koidzumi). Essential oils in A. macrocephala Koidz. and. A. lanacea DC. were isolated by a simultaneous steam distillation and extraction(SDE) method using n-pentane/diethy ether as solvent. A total of 30 and 28 components were identified by GC/MS from the essential oils of A. macrocephala Koidz. (18 hydrocarbons. 2 carbonyls, 5 alcohols, 5 esters) and A. lanacea DC.(14 hydrocarbons, 6 carbonyls, 4 alcohols, 3 esters, 1 acids), respectively. The major volatile flavor components in A. macrocephala Koidz. and A. lanacea DC. were furanodiene(27.9%, 15.7%), $\alpha$-cyperone(8.1%. 22.5% ), alloaromadendrene(2.9%, 4.7% ), (1,1-biphenyl)-4-carbon aldehyde 0%, 8.7% ) were found, respectively. Ten components including limonene, p-cymene, p-hymen-8-ol, (1,1-biphenyl)-4-carbox aldehyde were identified in A. lanacea DC, but not in A. macrocephala Koidz. and eight components including $\alpha$-copanene, isocaryophyllene, $\beta$-himahalene. germacrene B were and identified in A. macrocephala Koidz. but not in A. lanacea DC.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.127-135
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• 1989

The volatile components of nutmeg, cumin, cardamon, turmeric, coriander, clove, allspice, cassia, fennel, celery seed and black pepper, having a characteristic spicy aroma and being used as an ingradient of curry powder, were investigated. After steam distillation followed by extraction with diethyl ether: n-pentane(2:1, v/v) mixture, the volatile components were identified by capillary GC and GC/MS. As a result, following major compounds were identified. ${\alpha}-pinene(11.06%)$, ${\beta}-pinene(11.17%)$ and myristicin(19.98%) in nutmeg, cuminaldehyde(37.68%) in cumin, ${\alpha}-terpineol(47.33%)$ and 1, 8-cineol(20.56%) in cardamon, linalool(61.72%) in coriander, eugenol(63.63%) and eugenol acetate(20.59%) in clove, eugenol(80.12%) and methyl eugenol(10.85%) in allspice, cinnamaldehyde(82.29%) in cassia, anethole(79.92%) in fennel.