• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.1-13
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• 1982

Composite soil samples from 236 sites representing paddy field, up-land, orchard and plastic film house were examined for organochlorine residues by GLC-ECD. Detection frequencies and residual levels of most persistent organochlorine residues in the soil samples were found to depend on the cropping practices. Highest organochlorine residues were found in orchard soils and followed, in decreasing order, plastic film house, up-land and paddy field soils. ${\alpha}-Endosulfan$, dieldrin, p,p'-DDD and p,p'-DDT were responsible for the observed high organochlorine residues in the orchard soils. ${\alpha}-BHC$ and ${\gamma}-BHC$ were detected in all 236 soil samples. The mean residue levels of both BHC isomers were, however, remained fairly low. Residues of PCNB and ${\alpha}-endosulfan$ in native soils are reported, for the first time, in present work. PCNB was present in up-land plastic film house soils while ${\alpha}-endosulfan$ was found in all agricultural soils studied. High levels of p,p'-DDT and dieldrin were discussed in relation to crops cultivated, amount and duration of the pesticides usage. Need for continued observations on the persistent residue of pesticides in soils, already banned for general use, is emphasized.

• Membrane Journal
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• v.30 no.4
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• pp.252-259
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• 2020

Olefins are industrially important materials used for the synthesis of various petrochemicals. During the polymerization process, unreacted olefin monomers are discharged together with a large amount of nitrogen. For economic benefits, these olefin gases should be efficiently separated from nitrogen. In this study, a poly(glycidyl methacrylate-co-methyl methacrylate) (PGM) comb-like copolymer was synthesized and 4,4'-diaminoazobenzene (DAAB) was introduced to the copolymer to prepare a cross-linked membrane for C₃H₆/N₂ separation. PGM and DAAB were readily reacted at room temperature through an epoxide-amine reaction without additional thermal treatment. PGM-based membrane, which is a glassy polymer, showed a faster permeation of N₂ compared to C₃H₆. The pristine PGM membrane exhibited the N₂ permeability of 0.12 barrer and the high N₂/C₃H₆ selectivity of 32.4. As DAAB was introduced as a cross-linker, the thermal stability of the membrane was significantly improved, which was confirmed by TGA result. The N₂/C₃H₆ selectivity was decreased at 1 wt% of DAAB content, but the N₂ permeability increased by approximately 4.7 times. We analyzed N₂/C₃H₆ gas separation properties through a glassy polymer-based membrane, which has not been widely studied. Also, we proposed that thermal stability of the membrane can be greatly improved by the cross-linking method.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.634-646
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• 2016

In this work, modified epoxy resins which were well melted in mild solvent were synthesized and solubility assessment was carried out for synthesized epoxy resins. Bisphenol-A type, phenol novolac type and ortho-cresol novolac type epoxy resins were used and fatty acid, dodecyl phenol (DP) and toluene diisocyanate (TDI) were added for synthesis of modified epoxy resins containing fatty acid (MEFA). Composition was epoxy resin/fatty acid = 1.0/0.5 and fatty acid/DP = 0.25/0.25 by equivalent weight and twelve MEFAs were synthesized according to epoxy resins. Viscosity and solubility were measured for twelve MEFAs. As a result, solubility of MEFA was excellent for mild solvent according to increasement of contents of benzene ring, glycidyl group and carbon number of alkyl group. And physical properties were measured for each coating of paints after preparing transparent paints of MEFA to melt well in mild solvent among twelve MEFAs. As a result, they showed an optimal performance on conditions of equivalent ratio of bisphenol-A type epoxy resin/fatty acid/DP/TDI; 1.0/0.25/0.25/0.5 and equivalent ratio of phenol novolac type epoxy resin/fatty acid/DP; 1.0/0.25/0.25 for drying time, adhesion, hardness, impact resistance and alkali resistance.

• Journal of Adhesion and Interface
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• v.11 no.2
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• pp.41-49
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• 2010

Furan-containing epoxide monomers (8, 9) were designed and synthesized as carbon-neutral, environment-friendly adhesion material. Bicyclic skeleton were constructed using the Diels-Alder reaction of furan and methyl acrylate, both readily accessible starting material from a biomass via bio-refinery process. After reduction of ester functionality, resulting hydroxyl moieties were coupled to epichlorohydrin to provide the epoxy-functionalized furanic monomers (8, 9). The structure of new furanic monomers was confirmed by $^1H$ and $^{13}C$ NMR spectroscopy. As UV-curable monomers, basic properties such as UV curing time and the extent of UV curing were evaluated by photo DSC. Photo-curing shrinkages were measured by linear variable differential transformer transducer (LVDT) and the effect of molecular structure on shrinkage was considered. In addition, new synthetic compounds showed the shear strength over 3 MPa when they were photo-cured between polycarbonate plates, which indicates these compounds are feasible to use as photo-curable adhesive materials.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.1 no.2
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• pp.118-122
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• 2015

Suicidal gene therapy is based on the transduction of tumor cells with "suicide" genes encoding for prodrug-activating enzymes that render target cells susceptible to prodrug treatment. Suicidal gene therapy results in the death of tumor with the expression of gene encoding enzyme that converts non-toxic prodrug into cytotoxic product. Cytochrome P450 4B1 (CYP4B1) activates 4-ipomeanol (4-IPO) or 2-aminoanthracene (2-AA) to cytotoxic furane epoxide and unsaturated dialdehyde intermediate.In this study, therapeutic effects of suicidal gene therapy with rabbit CYP4B1/2-AA or 4-IPO system were evaluated in HT-29 (human colon cancer cell). pcDNA-CYP4B1 vector was transfected into HT-29 by lipofection and stable transfectant was selected by treatment of hygromycin ($500{\mu}g/mL$) for 3 weeks. Reverse transcription polymerase chain reaction (RT-PCR) analysis was performed for confirmation of CYP4B1 expression in CYP4B1 gene transduced cell. The cytotoxic effects of CYP4B1 transduced cell were determined using dye-exclusion assay after treatment of 2-AA or 4-IPO for 96 hrs. Dye-exclusion assay showed that $IC_{50}$ of HT-29 and CYP4B1 transduced HT-29 was 0.01 mM and 0.003 mM after 4-IPO or 2-AA treatment at 96 hrs exposure, respectively. In conclusion, CYP4B1 based prodrug gene therapy probably have the potential for treatment of colorectal adenocarcinoma.

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.365-370
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• 2019

In this study, effects of the ultrasonic irradiation during the reaction process were investigated for the enantioselective kinetic resolution (EKR) reaction of racemic epoxides in the presence of chiral cobalt salen catalysts, as compared to that of using the conventional mechanical stirring. In order to compare catalytic activities, the chiral cobalt salen complexes having $AlCl_3-$, $BF_3-$ and nitrobenzenesulfonic acid (NBSA) were synthesized and used as catalysts, and then three kinds of the racemic epoxides such as ephichlorohydrine (ECH), epoxy phenoxypropane (EPP) and propylene oxide (PO) were used as reactants. In addition, EKR reactions have been performed using the water and methanol as nucleophiles, respectively. The unique contribution of ultrasonic irradiation as a powerful mixing medium was evaluated in this study to improve the kinetics in comparison to the conventional mechanical agitation during EKR reactions. The reaction time to obtain the highest 99 ee% became shorten more than that of above 60%, when the ultrasonic irradiation was used. This result may be interpreted by the cavitation effect of ultrasound in the solution, generating a powerful shear force for the very violent mixing.

• Development and Reproduction
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• v.25 no.1
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• pp.15-24
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• 2021

Benzo[a]pyrene (B[a]P) is a potent carcinogen and is classified as an endocrine-disrupting chemical. In mammalian testes, Sertoli cells support spermatogenesis. Therefore, if these cells are negatively affected by exposure to xenotoxic chemicals, spermatogenesis can be seriously disrupted. In this context, we evaluated whether mouse testicular TM4 Sertoli cells are susceptible to the induction of cytotoxicity-mediated cell death after exposure to B[a] P in vitro. In the present study, while B[a]P and B[a]P-7,8-diol were not able to induce cell death, exposure to BPDE resulted in cell death. BPDE-induced cell death is accompanied by the activation of caspase-3 and caspase-7. Depolarization of the mitochondrial membrane and cytochrome c release from mitochondria were observed in benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE)-treated cells. These results indicate that TM4 cells are susceptible to apoptosis in a caspase-dependent manner. Western blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses showed that aryl hydrocarbon receptor (AhR) expression was almost undetectable in TM4 cells and that its expression was not altered after B[a]P treatment. This indicates that TM4 cells are nearly AhR-deficient. In TM4 cells, the CYP1A1 protein and its activity were not present. From these results, it is clear that AhR may be a prerequisite for CYP1A1 expression in TM4 cells. Therefore, TM4 cells can be referred to as CYP1A1-deficient cells. Thus, TM4 Sertoli cells are believed to have a rigid and protective cellular machinery against genotoxic agents. In conclusion, it is suggested that tolerance to B[a]P cytotoxicity is associated with insufficient AhR and CYP1A1 expression in testicular Sertoli cells.

• Korean Journal of Environmental Biology
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• v.40 no.3
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• pp.255-266
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• 2022

In crustaceans, molting is regulated by interactions between ecdysteroid and juvenile hormone (JH) signaling pathway-related genes. Unlike the ecdysteroid signaling pathway, little information on the role of JH signaling pathway-related genes in molting is available in zooplanktonic crustaceans. In this study, three genes (juvenile hormone acid O-methyltransferase (JHAMT), methoprene-tolerant (Met), and juvenile hormone epoxide hydrolase (JHEH)) which are involved in the synthesis, receptor-binding, and degradation of JH were identified using sequence and phylogenetic analysis in the brackish water flea, Diaphanosoma celebensis. Transcriptional changes in these genes during the molting cycle in D. celebensis were analyzed. Sequence and phylogenetic analysis revealed that these putative proteins may be functionally conserved along with those of insects and other crustaceans. In addition, the expression of the three genes was correlated with the molting cycle of D. celebensis, indicating that these genes may be involved in the synthesis and degradation of JH, resulting in normal molting. This study will provide information for a better understanding of the role of JH signaling pathway-related genes during the molting process in Cladocera.