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Gas chromatographic determination of phenol in fish tissues as a phenyl acetate derivative following solvent extraction of acidified samples

Kim H., Kim Y., Park S., Lee J., Choi J.

Acta Chromatographica

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2020

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Vol. 32, no. 1

64--67

EN

This study aimed to develop a chromatographic method to quantitatively determine phenol in fish tissues. This method involves solvent extraction of acidified samples, followed by derivatization to phenyl acetate and analysis with gas chromatography coupled with mass spectrometry (GC–MS). Phenol in a representative tissue sample (belly, gill, or renal tubules), which was homogenized with 2 N sulfuric acid, was extracted with ethyl acetate and derivatized to phenyl acetate using acetic anhydride and K2CO3 in water. An n-butyl acetate extract was injected into the GC–MS. The linearity (r2) of the calibration curve was greater than 0.996. The analytical repeatability, which is expressed as the relative standard deviation, was less than 6.14%, and the recovery was greater than 96.3%. The method detection limit and the limit of quantitation were 8.0 μg/kg and 26 μg/kg, respectively. The proposed method is also applicable to the analysis of other biological tissues for phenol and its analogs, such as pentachlorophenol.

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Enhanced Microwave Absorption of CNT Composites Mixing with Fe3O4 and Carbonyl Iron

Park J. H., Choi J., Lee K., Park J., Song J. K., Jeon E.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1513--1516

EN

We fabricated two different kinds of composite materials for absorbing microwave in a frequency range of 2 to 18 GHz using coaxial airline and thru-reflect-line (TRL) method. The composite materials having carbon nanotube (CNT) with carbonyl iron (CI) or iron oxide (Fe3 O4 ) were fabricated by mixing each components. Magnetic properties were measured by SQUID equipment. Complex permittivity and complex permeability were also obtained by measuring S-parameters of the toroidal specimen dispersing CI/CNT and Fe3 O4 /CNT into the 50 weight percent (wt%) epoxy resin. The real permittivity was improved by mixing the CNT however, the real permeability was same as pure magnetic powders. The CI/CNT had a maximum value of real permittivity and real permeability, 11 and 1.4 at 10 GHz, respectively. The CNT composites can be adapted to the radar absorbing materials, band width 8-12 GHz.

3

Flexible pavement analysis considering temperature profile and anisotropy behavior in hot mix asphalt layer

Choi J., Seo Y., Kim S. H., Beadles S.

Archives of Civil Engineering

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2011

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Vol. 57, nr 4

347-356

EN

A three Dimensional finite element model (FEM) incorporating the anisotropic properties and temperature profile of hot mix asphalt (HMA) pavement was developed to predict the structural responses of HMA pavement subject to heavy loads typically encountered in the field. In this study, ABAQUS was adopted to model the stress and strain relationships within the pavement structure. The results of the model were verified using data collected from the Korean Highway Corporation Test Road (KHCTR). The results demonstrated that both the base course and surface course layers follow the anisotropic behavior and the incorporation of the temperature profile throughout the pavement has a substantial effect on the pavement response predictions that impact pavement design. The results also showed that the anisotropy level of HMA and base material can be reduced to as low as 80% and 15% as a result of repeated loading, respectively.

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Parental provisioning in response to natural variation of brood size in the Black-billed magpie (Pica pica L.) : video analysis of behaviors in the nests

Lee S., Jabłoński P., Choe J., Choi J.

Polish Journal of Ecology

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2010

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Vol. 58, nr 3

553-562

EN

Natural selection will favor parents who adjust their effort in relation to the fitness costs and benefits from the current brood. In this study, we investigated how magpie parents adjust provisioning effort based on the number of nestlings in the brood, by analyzing video recordings of begging and feeding behaviors of birds. The number of visits per hour increased with brood size, but the number of feeding events per visit did not. Because of the latter, parental provisioning that a nestling is receiving on average decreased in larger broods. This may be viewed either as an evidence for the limitation of parental provisioning in larger broods, or as an evidence of parental strategy optimizing the brood-size-specific provisioning effort for the current reproductive event as a tradeoff between current and future reproduction. With other aspects of parental provisioning behavior, we did not find clear indication that parent confronts upper limitation in provisioning large broods. Pervisit number of feeding and nestlings. body condition around the time of fledging did not depend on brood size, which implies that parental effort is not at its limit in larger broods. Based on the results, we suggest that the provisioning effort of black-billed magpie parents is better explained by the life-history trade-off model for provisioning.