• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.454-465
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• 2015

The goal of this study is to investigate pre-service chemistry teachers’ understanding of the boiling process of a liquid mixture. We surveyed 65 students in the chemistry program of the College of Education about the boiling point of a 50%(by mole) ethanol aqueous solution and the temperature changes during heating. We then interviewed 9 of these students. According to the survey results, the percent of the pre-service teachers who thought that the boiling point of the ethanol solution would be ‘between the boiling points of ethanol and water (78-100 ℃)’ and ‘the same as that of ethanol’ were 52.3% and 35.4%, respectively. The majority of those who stated the former explained that the boiling point of the ethanol solution increased due to the effects of attraction or blocking by water molecules. Most of those who believed the latter explained that physical properties such as the boiling point would not be changed by the addition of water. With regard to the temperature change during heating, 69.2% of the teachers thought that the temperature would increase gradually while boiling, which some thought resulted from the increasing amount of water in the solution as the ethanol boiled off. Others thought that two temperature plateaus would be observed as each component of the liquid mixture underwent phase transition at its specific boiling point. When asked about the particle model of the gas phase during the boiling and evaporation process, some students drew both ethanol and water during evaporation but only ethanol when boiling. We discussed several alternative concepts of pre-service chemistry teachers about the boiling process of liquid mixtures and ways to improve their understanding.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.4
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• pp.563-570
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• 2007

This study was performed to observe the antioxidative effects, antimutagenic capacity, and cytotoxic activity of the 70% ethanol extract, and fractions, of Agaricus blazei Murill mycelium, using DPPH free radical scavenging ability, the Ames test, and SRB assay, respectively. Among the fractions, ethyl acetate showed the most effective antioxidative capacity according to the $RC_{50}$(73.6 $\mu$g/mL) of the scavenging effect on the DPPH radical. The inhibition rate of both the aqueous fraction and 70% ethanol extract(200 $\mu$g/plate) toward the Salmonella typhimurium TA100 strain was 94.6%, and it was 89.4% against the mutagenesis induced by MNNG(0.4 $\mu$g/plate). In addition, an identical concentration of the 70% ethanol extract in the TA98 strain, and the ethyl acetate fraction in the TA100 strain, showed inhibition rates of 80.3% and 76.9%, respectively, the highest activities against the mutagenesis induced by 4NQO(0.15 $\mu$g/plate). The cytotoxic effects of the 70% ethanol extract and its fractions increased with increasing sample concentration against human cervical adenocarcinoma(HeLa), human hepatocellular carcinoma(Hep3B), human breast adenocarcinoma(MCF-7), human stomach adenocarcinoma(AGS), and human lung carcinoma (A549). A 1 mg/mL concentration of the ethyl acetate fraction showed cytotoxicities of 77%, 83.8%, 82.1%, 83.1%, and 92.6% against HeLa, Hep3B, MCF-7, AGS and A549, respectively.

• Korean Journal of Organic Agriculture
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• v.20 no.3
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• pp.399-409
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• 2012

Effects of pretreatment and extraction conditions on total polyphenol yield from licorice root were investigated using statistical method. For pretreatment, heat treatment at $121^{\circ}C$ for 10 min was applied. Licorice root content in solvent (10, 20, and 30%) ethanol concentration (20, 40, and 60%) and reaction time (1, 2, and 3 h) were used as variables for extraction conditions. Two experiments, with heat treated and no treated licorice, were prepared with same experimental design. Box behnken design was employed and produced a total of 15 trials. Total polyphenol yield from licorice root was not affected by heat treatment. Among variables, licorice content in solvent showed most significant effect regardless of other variables (p<0.05). Finally, optimum conditions for the extraction of total polyphenol from licorice root was detected as following: 10% of licorice in solvent, 52% ethanol as solvent, 2 h of reaction time and non-heat treatment and the extraction yield from optimized condition was 17.6 mg/g licorice root.

• Journal of Life Science
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• v.16 no.6
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• pp.989-993
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• 2006

The antimicrobial substance from Pyrola japonica were extracted and isolated. Eighty percent ethanol extract of dried Pyrola japonica was fractionated to hexane, diethyl ether, ethyl acetate and aqueous layer. The hexane-soluble fraction showed the highest inhibitory activity against Bacillus subtilis. Moreover the hexane layer was fractionated into 5 groups by silica gel column chromatography. From the results, group No. 2 ($18{\sim}40$ fractions) showed the highest antimicrobial activity. The group was re-separated to 10 fractions by preparative thin layer chromatography and the peak I as active fraction was isolated by HPLC.

• Membrane Journal
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• v.23 no.5
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• pp.360-366
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• 2013

The Poly (vinylidene fluoride) and poly (acrylonitrile) (PAN) hollow fiber composite membranes coated with poly (vinyl alcohol) (PVA) and poly (acrylic acid) (PAA) as the crosslinkig agent are prepared. The resulting membranes were characterized for aqueous 90 wt% ethanol solution by pervaporation techniques in terms of the permeability and separation factor. In general, as both the crsslinking reaction temperature and the crosslinking agent concentration increase, the permeability decrease while the separation factor tends to increase. And also the permeability increased and the separation factor decreased as the feed temperature increased. Typically, the permeability $502g/m^2hr$ at the feed temperature $70^{\circ}C$ was obtained for PVDF hollow fiber membrane prepared with the crosslinking agent PAA 3 wt% at the reaction temperature $60^{\circ}C$ whereas the separation factor 218 was shown for the membrane reacted with PAA 11 wt% and at $100^{\circ}C$ for the feed temperature $50^{\circ}C$.

• Korean Journal of Materials Research
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• v.16 no.12
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• pp.754-760
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• 2006

Mercaptoundecanoic acid (MUA) has been used to enhance the dispersity of Au nanoparticles in organic solvent and the affinity between the Au nanoparticles surface and titanium dioxide shell in the synthesis of $Au/TiO_2$ core-shell composite nanoparticles. The dispersity of the MUA-coated Au nanoparticles in ethanol aqueous solution with different concentration of $H_2O$ was investigated by UV-Vis. absorption spectrum and the coating amount of MUA was varied from 0.02 mM to 1.0 mM. The MUA-coated Au nanoparticles were highly dispersed in pure $H_2O$ in the wide range of the coating amount of MUA. On the contrary, the MUAcoated Au nanoparticles showed an enhanced stability in the ethanol/$H_2O$=8/2 mixed solution only when the coating amount of MUA was 0.05 mM, and in the ethanol/$H_2O$=7/3 mixed solution when the coating amount of MUA was in the range from 0.02 mM to 0.17 mM. From this systematic study, it can be inferred that the stability and the dispersibility of Au nanoparticles in organic solvents are highly sensitive towards the amount of MUA coating.

• Natural Product Sciences
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• v.29 no.2
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• pp.74-82
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• 2023

Nepeta sibirica L. or Siberian catmint is a medicinal plant species used in Mongolian traditional medicine for curing human different disorders and veterinary practices. The previous study of the whole plant concentrated on the determination of its essential oil composition and reported that the major ones are sesquiterpenes, including nepetalactone. The aim of this study was to reveal a new biological activity of the above-ground parts of N. sibirica L. and compare the activity of different extracts correlating with the content of biologically active compounds and evaluate their toxicity. For this purpose, anti-oxidative and acetylcholinesterase inhibitory activities of the above-ground parts of N. sibirica L. aqueous and ethanol (EtOH) (40%, 70%) extracts were assayed spectrophotometrically. The aqueous extract showed positive anti-oxidative activity by both tested DPPH and FRAP assays with IC₅₀ 134.24 ± 1.42 mg/mL and FRAP value 1385.15 ± 8.12 µmol/L at 200 ㎍/mL, in contrast to 40% and 70% EtOH extracts. The 70% EtOH extract presented the highest acetylcholinesterase inhibitory activity (IC₅₀ 77.29 ± 0.38 mg/mL) followed by 40% EtOH extract (176.72 ± 0.35 mg/mL) and aqueous extract (275.41 ± 0.23 mg/mL). Total phenolics were found to be gallic acid equivalent, % 3.74 ± 0.05 (70% EtOH), 3.94 ± 0.04 (40% EtOH), and 3.79 ± 0.16 (aqueous), whereas the total flavonoids as a rutin equivalent, % as 2.01 ± 0.12, 1.44 ± 0.17 and 1.99 ± 0.02, each. The aqueous extract showed the best anti-oxidative and lowest activity against the acetylcholinesterase; however, the 70% EtOH extract showed the opposite effects than that of the aqueous. No mortality incidence was visible at various doses, indicating that the oral median lethal dose of aqueous and 70% EtOH extracts were considered greater than 5000 mg/kg. N. sibirica L. belongs to the non-toxic category of the OECD 423 classification.

• Journal of Animal Science and Technology
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• v.52 no.5
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• pp.383-388
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• 2010

Identification of natural compounds that can prevent the development of obesity in vivo is time consuming and expensive. We have used in vitro systems derived from pig adipose tissue to screen simple aqueous or ethanolic extracts of Korean medicinal herbs (KMH) for their anti-adipogenic potential. A total of 183 extracts were tested for their actions in lipogenesis of pig adipose tissue and differentiation of pig preadipocytes. Ethanol extracts were prepared from 72 and aqueous extracts were prepared from 111 medicinal herbs. Both an ethanolic and an aqueous extract were prepared from 65 of these. Thirteen extracts substantially altered rates of lipogenesis in vitro. The effects of KMH on lipogenesis of pig adipose tissue are as follows. Elevens reduced lipogenesis to rates that were more than 40% lower than control and four of these reduced rates of lipogenesis by more than 70%. The most potent anti-lipogenic extracts were those obtained in ethanol from Iridaceae and from Sophora flavescens AIT as well as both the aqueous and ethanolic extracts from Lysimachia vulgaris L. Two extracts, those prepared in water from Caesalpiniae lignum and from Phellodendri cortex, were found to promote rates of lipogenesis in vitro. The effects of KMH on differentiation of pig preadoipocytes are as follows. Twentyeight extracts altered the rates of differentiation of cultured porcine preadipocytes. Sixteen increased and twelve reduced the rates of differentiation of preadipocytes. Extracts prepared in ethanol from Moutan radicis cortex and from Ostericum koreanum and those prepared in water from Angelicae gigantis radix, from Inula henenium L and from Magnolia flos doubled the rate of differentiation of cultured porcine preadipocytes. Ten extracts reduced the in vitro rate of differentiation of porcine preadipocytes by more than 35%. These were the ethanolic extracts from Glycyrrizae radix, Nepetae spica and from Polygala myrtifolia and the aqueous extracts from Amaranthaceae, Asparagus cochinchinesis, Atractylodis rhizoma alba, Citrus junos TANAKA, Cyperus rotundus, Epimedium grandiflorum and from Moutan radicis cortex. Only the ethanolic extract from Polygala myrtifolia was able to both reduce lipogenesis in adipose tissue slices and retard differentiation of cultured preadipocytes. The results of our study will provide meaningful information to identify medicinal herbs which would reduce fat deposition in livestocks and humans.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.04a
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• pp.62-64
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• 1996

Chitin, which is obtained mainly from the cuticle of a marine crustacean, has recently aroused great interest in its industrial and biomedical applications. Chitosan, deacetylated form of chitin, appears to be more useful for biomedical application and dehydration of aqueous solutions than chitin, since it has both hydroxyl and amino groups that can be modified easily. Amino groups on chitosan reacts with dialdehyde to form a Schiff base and then crosslinked, and can be easily neutralized with sulfuric acid and metal ions. Polyfunctional metal ions can form a metal-polyelectrolyte complexes with chitosan. Membranes used in modules so far working in industrial pervaporation plants are generally of composite type. This composite membrane was prepared by coating a porous polysulfone ultrafiltration membrane support of definite structure with a thin, dense layer of permselective chitosan. To apply industrial scale pervaporation process for dehydration of aqueous ethanol and isopropanol, chitosan composite membranes were prepared and tested at various conditions.

• Journal of Environmental Health Sciences
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• v.31 no.3
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• pp.221-226
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• 2005

Isoflavone was extracted with various concentration of aqueous methanol using whole hypocotyls as the starting material. Whole hypocotyls were preferred as the raw material because the residue could be easily removed from the solvent after the extraction process. Extraction yield was almost constant at the methanol concentration of $20-80\%$. Most of the isoflavone was extracted within 1 hr, and the extraction yield remained almost constant thereafter. When the concentration of methanol was $80\%$, the content of total solid was reduced due to the reduced extraction of contaminating protein as the result of protein insolubilization. Among resins tested, Diaion HP-20, Amberlite XAD-16, and Amberlite IRC-50 showed the highest capacity to absorb the compound. Open column chromatography with Diaion HP-20 showed that $80\%$ aqueous ethanol was most efficient as the eluting solvent with final recovery of the phytochemical being more than $95\%$. Maximum adsorption of the phytochemical occurred at the acidic pH 2-4. When the spatial velocity was increased to 15 and more, the degree of adsorption was decreased, whereas below spatial velocity of 15, the adsorption capacity of isoflavone to the resin was almost constant. The purity of the isoflavone purified by column chromatography was $78\%$.