• Korean Journal of Food Science and Technology
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• v.27 no.1
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• pp.124-128
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• 1995

The present study was conducted to elucidate nitrite scavenger derived from seeds of Cassia tora L. Methanolic extract of Cassia tora L was refractionated into ethyl ether, chloroform, ethyl acetate and water farction, and nitrite scavenging abilities of these fractions were investigated. Among these fractions, ethyl acetate fraction had the strongest nitrite scavenging ability(97%/2 mg). Therefore, to further investigate nitrite scavenger, ethyl acetate fraction was fractionated by silica gel column chromatography with a chloroform-methanol($10:0{\sim}0:10$) and then compound A and B were isolated. Compound A had a stronger nitrite-scavenging effect than compound B. Therefore the further separation of compound A was carried out by HPLC(32% acetonitrile. 1 ml/min) using ${\mu}Bondapak$C18 column$(3.9{\times}300 mm)$ and finally compound A-1 was obtained from compound A. Compound A-1 had by far nitrite-scavenging ability as compared with that of ascorbic acid. Compound A-1 was identified as $nor-rubrofusarin-6-{\beta}-mono-D-glucoside$ from the profiles of UV, IR and $^1H-NMR$.

• Elastomers and Composites
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• v.51 no.2
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• pp.128-137
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• 2016

The effect of the surface area of silicas on their reinforcing performance to styrene-butadiene rubber (SBR) compounds was systematically investigated. The feasibility of the Brunauer-Emmett-Teller surface area ($S_{BET}$) as a parameter representing the characteristics of the silicas was discussed compared to the mesopore volume, c value, oil absorption, and uptake of silane. The increase in $S_{BET}$ of silicas caused a considerable increase in Mooney viscosity, minimum torque, and hysteresis loss of the silica-filled SBR compounds, while significantly enhancing their abrasion property. These changes were explained by the attrition between the hydrophilic silica surface and the hydrophobic rubber chains. As expected, the change in $S_{BET}$ did not induce any remarkable changes in the cure, processing, tensile, and dynamic properties of the silica-filled SBR compounds because the crosslinking density of the rubber chains mainly determined these properties.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.437-444
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• 2010

This study was conducted to determine the herbicidal activity of allelochemicals and identify herbicidal compounds in bulbs of Lycoris chinensis var. sinuolata. Methanol extract was purified by a series of silica gel flash column chromatography and HPLC. The final HPLC gave two active fractions and an herbicidal compound was obtained. By GC/MS analysis, the herbicidal compound was identified as montanine ($O^2$-methyl pancracine), an isoquinoline alkaloid. Montanine showed 100% of growth inhibition on the shoot and root of barnyardgrass (Echinochloa crus-galli) seedlings at $50\;{\mu}g\;mL^{-1}$ as compared with the control.

• Applied Biological Chemistry
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• v.46 no.3
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• pp.268-270
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• 2003

Methanol extract obtained from aerial parts of Platycarya strobilacea was successively fractionated with n-hexane, ethylacetate, n-butanol, and water. From ethylacetate fraction, an active compound was isolated through repeated silica gel column chromatography and was identified as 5-hydroxy-2-methoxy-1,4-naphthoquinone by MS and NMR analyses. The compound showed in vivo 76% antifungal activity at $100\;{\mu}g/ml$ against tomato late blight disease.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.2
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• pp.115-122
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• 2003

This experimental study on high strength lightweight concrete using compound materials has been performed. In which, expanded clay was used as coarse aggregate, and silica fume and fly ash as admixtures varying by 0, 10% and 0, 5, 10, 15, 20% of cement amount respectively were added. Thus, the properties of fresh and hardened concrete have been investigated. The results of this study can be summarized as follows ; Each slump loss of mixtures replaced fly ash has been decreased by increasing replacement rate. The compressive strength have shown 465, 428 and $401kgf/cm^2$ at 30, 40 and 50% of W/B in 28days respectively, all of which have satisfied the criterion $270kgf/cm^2$ of high strength lightweight concrete. The unit volume weight of hardened concrete has been decreased by increasing replacement rate of silica fume and fly ash, values of which have satisfied the criterion $2000kgf/cm^3$of light weight concrete.

• Applied Biological Chemistry
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• v.38 no.6
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• pp.577-580
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• 1995

During the screening for the antimicrobial agents against multidrug-resistant Staphylococcus aureus, we isolated an active compound produced by strain CNU30122. The active compound was purified from culture broth by HP-20 column chromatography, ethylacetate extraction. silica gel column and Sephadex LH-20 column chromatographies and HPLC. Based on various NMR studies including $^1H-^1H\;COSY$, $^1H-^{13}C\;COSY$ and HMBC experiments. the active compound was identified as fusidic acid.

• Rubber Technology
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• v.17 no.1_2
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• pp.18-33
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• 2016

• Elastomers and Composites
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• v.56 no.1
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• pp.32-42
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• 2021

The vulcanizate structure of silica-filled compounds is affected by the filler-rubber interaction (FRI) due to the silica-rubber coupling reaction and the chemical crosslink density (CCD) of the matrix rubber. In this study, the vulcanizate structure changes of silica-filled compounds according to the silane and sulfur variation were quantitatively analyzed using the Flory-Rehner and Kraus equations. In efficiency vulcanization (EV) conditions with low sulfur content, FRI increased when the bis-[3-(triethoxysilyl)propyl]tetrasulfide (TESPT) content increased, and the CCD clearly decreased. By contrast, in semi-EV conditions with high sulfur content, as TESPT content increased, the FRI increased the same way EV conditions, but the CCD was unchanged. Based on these results, it was confirmed that FRI of the silica-filled compounds increased as TESPT content increased, but CCD decreased or retained similar values according to the vulcanization system, indicating that the formation reaction of FRI was preferred over CCD.

• Elastomers and Composites
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• v.59 no.1
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• pp.8-16
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• 2024

As regulations on greenhouse gas emission have strengthened globally, the demand for improved fuel efficiency in automobiles continues to rise. In response, the tire industry is actively conducting research to improve fuel efficiency by enhancing tire performance. In this study, silica-filled epoxidized natural rubber (ENR)/butadiene rubber (BR) blend compounds were manufactured according to ENR types and silica contents, and their physical properties and vulcanizate structure were evaluated. ENR-50, which has a higher epoxide content than ENR-25, exhibited stronger filler-rubber interaction, resulting in superior abrasion resistance. In addition, because of its high glass transition temperature (T_g), the wet grip performance of ENR-50 improved, even though the rolling resistance increased. Increasing the amount of silica had little effect on the abrasion resistance due to the increase in filler-rubber interaction and decrease in toughness. In addition, ENR-50 exhibited better wet grip performance; however, the rolling resistance increased. The results indicated that truck bus radial (TBR) tire tread compounds can be designed by applying ENR-50 to improve wear resistance and wet grip performance. In addition, by applying ENR-25 and reducing the silica contents improve fuel efficiency.

• Microbiology and Biotechnology Letters
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• v.25 no.2
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• pp.183-188
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• 1997

Antimicrobial activity of various extracts of Xanthium strumarium L. was tested against 25 strains of bacteria, yeast and fungus. The crude ethylacetate extract exhibited strong growth inhibition to the tested strains with the exception of partial Gram-negative bacteria. The property of antimicrobial compound was very stable under heat treatment at $120^{\circ}C$, but it was unstable in acid (pH 3.0) and alkali (pH 10.0) treatment. The antimicrobial compounds were purified by boiling water extraction, ethylacetate extraction, charcoal column chromatography, silica gel column chro- matography and reverse phase HPLC. The purified compound A and B were detected in a single peak (each above 98% purity) through the HPLC analysis. The compound A and B showed a strong growth inhibition against Gram-negative and positive bacteria in the agar diffusion method. When tested by the FDA method using the esterase, compound A mainly inhibited the growth of bacteria and compound B showed the growth inhibition of both bacteria and yeasts.