• Applied Biological Chemistry
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• v.36 no.2
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• pp.99-104
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• 1993

In order to explore the brassinosteroid-active component in Cassia tora, methanol extract of immature seeds was purified by sequences of solvent fractionation, silica gel adsorption chromatography, Sephadex LH-20 chromatography, charcoal adsorption chromatography and Bondesil chromatography. The activity of brassinosteroid was monitored by the rice inclination test and its presence could be confirmed in each purification step. The purified active components were separated by silica gel adsorption chromatography. Brassinosteroid substances in separated active fractions were identified as teasterone, castasterone, brassinolide by TLC and HPLC. Our work is probably the first report of endogenous brassinosteroid in Cassia tora. The content of brassinosteroid in Cassia tora as converted into brassinolide was $3.5{\sim}5.5\;ng/g$ fresh weight. The order of brassinosteroid contents was toward to be teasterone, castasterone, brassinolide.

• Journal of the Korean Society of Tobacco Science
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• v.16 no.2
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• pp.181-190
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• 1994

Various active carbons were made from plant sources of coconut shell, pine tree, oak tree and lignite coal. Pore characteristics of these adsorbents were investigated. 1, With increasing activation time, specific surface area and pore volume increased, but the development of micropores was limited at a certain level. The average pore diameter, by BET, of coconut active carbon was 15.5-21.8$\AA$ and that of lignite carbon was 15.6-31.3$\AA$. The pore diameters of silica-gel, sepiolite and zeolite was 30.9$\AA$, 58.6$\AA$ and 55.7$\AA$, respectively. 2. The Horvath - Kawazoe micropore diameter of coconut shell active carbon was under 10.5$\AA$ and that of the other active carbon was under 20.9$\AA$ but silica-gel 33$\AA$, sepiolite 103 $\AA$ and zeolite was unexpectedly large to be 175$\AA$. From the difference between BET micropore diameter and Howath - Kawazoe diameter, it could be said that silica - gel has comparatively uniform pore diameter but sepiolite and zeolite have very uneven diameter. 3. Total pore volume of coconut shell active carbon was 0.27-1.04 cm3/g but that of the other active carbon, 0.23-0.62 cm3/g, was much lower than that of coconut shell active carbon. Hydrophilic adsorbent silica - gel and sepiolite showed big difference in specific surface area, but pore volumes of these were 0.47 and 0.56 cm3/g showing similar value and micropore volumes of these were, respectively, 0.06 cm3/g and 0.04 cm3/g. Total pore volume of zeolite was 0.1 cm3/g and that of micropore was only 0.02 cm3/g.

• Journal of the Korean Ceramic Society
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• v.54 no.1
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• pp.49-54
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• 2017

In this study, based on hydrolysis and condensation via $St{\ddot{o}}ber$ process of sol-gel method, synthesis of mono-dispersed silica nanoparticles was carried out with hydrophilic solvent. This operation was expected to be a more simplified process than that with organic solvent. Based on the sol-gel method, which involves simply controlling the particle size, the particle size of the synthesized silica specimens were ranged from 30 to 300 nm by controlling the composition of tetraethylorthosilicate (TEOS), DI water and ammonia solution, and by varying the stirring speeds while maintaining a fixed amount of ethanol. Increasing the content of DI water and decreasing the content of ammonia caused the particle size to decrease, while controlling the stirring speed at a high level of RPMs enabled a decrease of the particle size. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were utilized to investigate the success factors for synthesizing process; Field emission scanning electron microscopy (FE-SEM) was used to study the effects of the size and morphology of the synthesized particles. To analyze the dispersion properties, zeta potential and particle size distribution (PSD) analyses were utilized.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.73-79
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• 1968

The resolving capacities of xanthophyll pigments on thin-layers of Silica Gel, Hyflo super-Cel, and Micro-Cel C with varying concentrations of acetone in petroleum ether as the developing solvent were compared. The results showed that the resolving capacity of Micro-Cel C thin-layer was superior to others and satisfactory for the separation of leaf carotenoids in clearly separated six bands; carotenes, lutein-zeaxanthin, antheraxanthin, violaxanthin, an unidentified band, and neoxanthin, when it was developed with $13\%$ acetone-petroleum ether solution for 15 to 20minutes in an unsaturated chamber. Adhension of Micro-Cel C to glass was adequate without binder. Calcium sulfate used as a binder appeared to inactivate the resolving capacity of Micro-Cel C. Removing an about 0.2cm-wide layer on bo side of thin-layer slide helped to prevent 'edge effect' which gave tailing and faster solvent ascending along the side than the center. An adequate thickness of thin-layer was obtained when a 3 ml aliquot of the suspension in which l0g powdered Micro-Cel C was suspended in 75 ml distilled water was coated on a $2\times20cm$ glass slide.

• Applied Biological Chemistry
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• v.40 no.2
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• pp.163-166
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• 1997

A yeast, Torulopsis bombicola, was cultured in the media fortified with soybean oil as a additional carbon source for 7 days with reciprocal shaking. From the culture broth, sophorose-lipid was isolated and treated with alkali to afford sophorose. The sophorose contained in the medium was acetylated and isolated through silica gel column chromatography. The aceylated sophorose was hydrolyzed with 5% KOH at room temperature to give rise to sophorose. Meanwhile, the MeOH extracts obtained from the pod of Sophora japonica was solvent-fractionated with n-BuOH and $H_2O$, and butanolic layer was chromatographed on silica gel column to afford a flavonoide-glycoside. The glycoside was hydrolyzed with 0.02 N $H_2SO_4$ to yield sophorose.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.600-603
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• 1996

The methanol extract of Aralia elata bark showed antimicrobial activities against bacteria, yeast and fungi. The active components were successively purified with solvent fractionation, silica gel adsorption column chromatography, Sephadex LH-20 column chromatography, silica gel partition column chromatography and HPLC. The active substances were separated with HPLC where 1% acetic acid-MeOH (60 : 40, v/v) was used as mobile phase. The isolated active substance ($t_r$ 17.1 min) was identified as trans-3,4-dihydroxycinnamic acid by $MS,\;^1H-NMR\;and\;^13C-NMR$.

• Journal of Applied Biological Chemistry
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• v.55 no.2
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• pp.103-107
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• 2012

Acanthopanax sessiliflorus Seeman fruits (Araliaceae) were extracted at room temperature with 70% aqueous ethanol (EtOH). The concentrated extract was partitioned with ethyl acetate (EtOAc), n-butyl alcohol, and $H_2O$, successively. From the EtOAc fraction, four compounds were isolated through the repeated silica gel and octadecyl silica gel (ODS) column chromatographies. According to the results of physico-chemical and spectroscopic data including NMR, IR, and gas chromatography/mass spectrometer, the chemical structures of the compounds were determined as stigmasterol (1), linoleic acid (2), ${\beta}$-sitosterol (3), and stigmast-5-en-$3{\beta}$,$7{\beta}$-diol (4).

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.363-368
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• 2021

The fruits of tomato (Lycopersicon esculentum) were extracted with 70% aqueous methanol (MeOH) and the concentrates were partitioned into ethyl acetate (EtOAc), n-butanol (n-BuOH), and water (H₂O) fractions. The repeated silica gel (SiO₂) and octadecyl silica gel column chromatographies for the EtOAc fraction, whose activity was confirmed, led to isolation of one flavone compound. Nuclear magnetic resornance, infrarad spectroscopy, and mass spectroscopy (MS) revealed the chemical structure of the isolated compound, 5,7,3'-trihydroxy-6,4',5'-trimethoxyflavone (1). LC-MS/MS analysis determined the content level of compounds 1 in the MeOH extract to be 4.02±0.12 ㎍/mg and in the TME-10 fraction to be 0.96±0.03 ㎍/mg. Through this study, the antioxidantive capacity was confirmed by demonstrating that the L. esculentum extract and their fractions showing an increase in glutathione mean and a decrease in glutathione heterogeneity uniformly raises the intracellular glutathione level.

• Journal of the Korean GEO-environmental Society
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• v.22 no.12
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• pp.59-63
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• 2021

This study presented the characteristics and additive effects of the grout with mixing ratio for developing of high-efficiency grouting technology under high depth conditions. The laboratory investigation were conducted with Portland cement (OPC) and micro cement (S8000-E) including viscosity experiments, particle size analysis experiments, Gel-Time experiments and uniaxial compressive strength experiments. As a result of the viscosity experiment, it was shown that OPC is advantageous in terms of viscosity, but S8000-E is suitable when considering the passage of rock joint intervals through particle size analysis. The Gel-Time experiment shows that it is not that difficult with injection as a grout material even when silica fume (SF) was applied. The strength of the cured material is improved as increase in the content of silica fium (SF). Within the range of the study, the optimal mixing ratio obtained through various experiments is S8000-E, w/c=70%, silica fium (SF)=6%, and 7 days.

• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.162-168
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• 2007

Silica wet gels were prepared ken water glass ($29\;wt%\;SiO_{2}$) by using Amberlite as a ion exchange resin. After washing in distilled water, the wet gels were further aged in a solution of TEOS/EtOH to strengthen of 3-dimensional network structure. As increase TEOS content in aging solution, BET surface area and porosity of the ambient dried silica aerogels were significantly decreased, and average pore diameter was also decreased 30 nm to -10 nm. Also, higher density and compressive strength were obtained in case of higher TEOS content. This is due to precipitation of $SiO_{2}$ nano particles by TEOS. Hence, TEOS addition plays an important role of both strengthening and stiffness of silica wet gel network. By adding over 30 vol% TEOS, a crack-free monolithic silica aerogel tiles were obtained and its density, compressive strength, and thermal conductivity were shown $0.232g/cm^{3}$, 7.3 MPa, and 0.029 W/mk, respectivly.