• Environmental Engineering Research
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• v.11 no.4
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• pp.232-240
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• 2006

Polychlorinated naphthalenes (PCNs) formed along with dibenzo-p-dioxin and dibenzofuran products in the slow combustion of dichlorophenols (DCPs) at $600^{\circ}C$ were identified. Each DCP reactant produced a unique set of PCN products. Major PCN congeners observed in the experiments were consistent with products predicted from a mechanism involving an intermediate formed by ortho-ortho carbon coupling of phenoxy radicals; polychlorinated dibenzofurans (PCDFs) are formed from the same interemediate. Tautomerization of the intermediate and $H_2O$ elimination produces PCDFs; alternatively, CO elimination to form dihydrofulvalene and fusion produces naphthalenes. Only trace amounts of tetrachloronaphthalene congeners were formed, suggesting that the preferred PCN formation pathways from chlorinated phenols involve loss of chlorine. 3,4-DCP produced the largest yields of PCDF and PCN products with two or more chlorine substituents. 2,6-DCP did not produce tri- or tetra-chlorinated PCDF or PCN congeners. It did produce 1,8-DCN, however, which could not be explained.

• Journal of Environmental Health Sciences
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• v.35 no.6
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• pp.510-516
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• 2009

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in soil samples of Ansung in Kyonggi-province to investigate concentration distribution of PBDEs and PCBs. The 10 soil samples were collected using a stainless steel hand-held corer that was cleaned before and after each sample using hexane. Total concentration of PBDE and PCBs were 2,205.3 and 348.1 pg/g dry weight (DW) in soil sample, respectively. BDE-209 showed as the most abundant congener in soil samples which was related to imported amount and usage amount of deca-BDE technical mixture in Korea. Also, BDE-99, BDE-47, BDE-100 deposition in soil sample was higher than other congeners and was related to the imported and usage amount reported for penta-BDE technical mixture in Korea. Correlation coefficient between PBDE contribution and technical mixture formulation (Bromokal 70-5DE) were significant (r=0.91, p<0.01) which suggests the influence of sources in this technical mixtures.

• Molecules and Cells
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• v.23 no.3
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• pp.379-390
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• 2007

We sequenced and characterized the complete mitochondrial genome of the Japanese fish tapeworm D. nihonkaiense. The genome is a circular-DNA molecule of 13607 bp (one nucleotide shorter than that of D. latum mtDNA) containing 12 protein-coding genes (lacking atp8), 22 tRNA genes and two rRNA genes. Gene order and genome content are identical to those of the other cestodes reported thus far, including its congener D. latum. The only exception is Hymenolepis diminuta in which the positions of trnS2 and trnL1 are switched. We tested a PCR-based molecular assay designed to rapidly and accurately differentiate between D. nihonkaiense and D. latum using species-specific primers based on a comparison of their mtDNA sequences. We found the PCR-based system to be very reliable and specific, and suggest that PCR-based identification methods using mtDNA sequences could contribute to the study of the epidemiology and larval ecology of Diphyllobothrium species.

• YAKHAK HOEJI
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• v.50 no.4
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• pp.293-299
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• 2006

The aim of present study was to investigate the possible influence of Rho-kinase inhibition on the plant-derived estrogen-like compounds-induced arterial relaxation. Agonist- or depolarization-induced vascular smooth muscle contractions involve the activation of Rho-kinase pathway. However there are no reports addressing the question whether this pathway is involved in genistein-or daidzein-induced vascular relaxation in rat aortae precontracted with phenylephrine or thromboxane $A_2$ mimetic U-46619. We hypothesized that Rho-kinase inhibition plays a role in vascular relaxation evoked by genistein or daidzein in rat aortae. Endothelium-intact and denuded arterial rings from male Sprague-Dawley rats were used and isometric contractions were recorded using a computerized data acquisition system. Genistein concentration-dependently inhibited phenylephrine or thromboxane $A_2-induced$ contraction regardless of endothelial function. Surprisingly, in the agonists-induced contraction, similar results were also observed in aortae treated with daidzein, the inactive congener for protein tyrosine kinase inhibition, suggesting that Rho-kinase might act upstream of tyrosine kinases in phenylephrine-induced contraction. In conclusion, in the agonists-precontracted rat aortae, genistein and daidzein showed similar relaxant response regardless of tyrosine kinase inhibition or endothelial function.

• Journal of the Korean Applied Science and Technology
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• v.38 no.5
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• pp.1219-1228
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• 2021

Rhamnolipids are recognized as eco-friendly biosurfactants and produced by the bio-process employing bacteria. Pseudomons aeruginosa is well-known to produce rhamnolipids in high yield during fermentation process. Rhamnose and 𝛽-hydroxylated fatty acid are main chemicals for rhamnolipids, which are produced in the form of congener mixtures. In this paper, the synthetic mechanism of rhamnolipids within bacteria cells was presented in part and foam control technologies were qualitatively described. Foam control during fermentation process was important to regulate a continuous process. During last decade, the technologies are developed enough to challenge to a commercial-scale production. In particular, rhamnolipids will be more valuable if these can be applicable to value-added chemicals, such as medicines.

• Korean Journal of Ichthyology
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• v.17 no.4
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• pp.236-240
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• 2005

A new species, Cobitis zhejiangensis, is described based on 32 specimens collected in the Ling River, Xianju District, Taizhou City, Zhejiang Province, China. The new species superficially resembles Cobitis sinensis, but is distinguished from that species by the following features: deeper body (17.3% versus 14.9% of SL), shorter caudal peduncle length (12.0% versus 13.5% of SL), deeper caudal peduncle depth (11.4% versus 9.5% of SL), color pattern of second Gambetta's zone (rounded ovoidal dots-narrow elongate bloches). Deep caudal peduncle depth and short caudal peduncle length (cpd/cpl : 95.2%) and the color pattern of second Gambetta's zone are the unique features of this species not shared with any other congener species of China.

• Analytical Science and Technology
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• v.14 no.2
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• pp.147-158
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• 2001

Polychlorinated dibenzo-p-dioxins(PCDDs), dibenzofurans(PCDFs), and biphenyls(PCBs) were analyzed by HRGC/HRMS in human blood samples from the Siwha industrial area in Korea. The PCDD/F and PCB concentrations in workers were higher than those in residents. The average TEQ concentrations of PCDD/Fs in workers and residents were 40.3 pg I-TEQs/g lipid and 16.6 pg I-TEQs/g lipid, respectively, and the total PCB concentrations were 174.1 ng/g lipid and 151.0 ng/g lipid, respectively. When applied to principal component analysis, the PCDD/F congener distributions of workers were differentiated from those of residents. But, all of them were similar to the distribution in several Korean foods. Estimated daily intake(EDI) of each person was calculated, and then only 40% to the total people were within the tolerable daily intake range(1-4pg I-TEQ/kg bw/day) suggested by WHO(1997).

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.792-796
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• 2003

Polychlorinated dibenzo-p-dioxins (PCDDs) are extremely toxic and persistent environmental pollutants. Their chemical reactivities and other physicochemical/biological properties show a strong dependence on the chlorination pattern. With increasing the number of chlorines, dioxin congeners become more electronegative and gain higher electron affinities. The vertical electron affinities (VEA) are related with the LUMO energies of neutral molecules. LUMO energies of all PCDD congeners were calculated at the B3LYP/6-31G** level and those of some selected congeners at the level of B3LYP/6-311G**//B3LYP/6-31G** and B3LYP/cc-pvtz/ /B3LYP/6-31G**. The total energies of neutral and anionic species for dibenzo-p-dioxins (DD), 1469-TCDD, 2378-TCDD, and OCDD were calculated at the level of B3LYP/6-31G**, B3LYP/aug-cc-pvdz, and B3LYP/ aug-cc-pvtz//B3LYP/6-31G**. By using the four congeners with D2h symmetry as reference molecules, we could estimate VEA (B3LYP/aug-cc-pvdz) of 75 PCDD congeners based on the linear correlations between LUMO energy and VEA (B3LYP/6-31G**) and between VEA (B3LYP/6-31G**) and VEA (B3LYP/aug-ccpvtz// B3LYP/6-31G**). Results show that all PCDDs with the number of Cl ≥ 3 have positive electron affinities. The PCDD electron affinity values provided in this work can be a useful data set in understanding the congener-specific reactivities of dioxins in various environmental media.

• Journal of Environmental Health Sciences
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• v.42 no.2
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• pp.102-111
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• 2016

Objectives: This study was conducted to evaluate the use of polyurethane foam disk passive air samplers (PUF PAS) for better measurement of atmospheric polychlorinared dibenzo-p-dioxins/furans (PCDD/Fs) concentrations compared to PUF PAS combined with high volume air samplers (HVS). Methods: Air samples were collected by a low volume air sampler (LVS) and PUF PAS. A total of two pairs were continuously collected for six months, but the PUF was replaced every two months. Results: A good correlation was shown ($R^2=0.8595$, p<0.0001) between atmospheric PCDD/Fs concentration measured by the LVS and PUF PAS. The average air sampling rate ($1.5m^3/day-sampler$) of all PCDD/Fs congeners showed a middle of the means which were measured using a HVS by other researchers in different cities. In addition, the air sampling rates of the LVS for each congener made less difference than did those of the HVS. Conclusion: It was found that measurements using the LVS were less influenced by atmospheric peak PCDD/Fs concentrations. However, trace POPs such as PCDD/Fs may involve relatively large analytical errors in measurement, and as a result the air sampling rate of the respective PCDD/Fs isomer is also likely to involve errors. The method of using a regression straight line between the concentrations obtained from the LVS and those from the PUF PAS was judged higher than the method using the air sampling rate, since the former compensated for the experimental errors in the process of evaluation of atmospheric PCDD/F concentrations using the PUF PAS.

• Journal of Environmental Health Sciences
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• v.36 no.2
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• pp.118-127
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• 2010

Bivalve samples from 30 locations Korean coastal waters were analyzed to characterize the contamination with and distribution of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). The congeners of PBDE in 30 bivalve samples were analyzed by high resolution gas chromatography with a high resolution mass detector. The levels of PBDEs in bivalve samples ranged from 0.092 to 13.5 ng/g wet weight. These values for PBDEs concentrations in bivalves from Korea were higher than or comparable to available values for bivalves from other countries. In the congener profiles, BDE-47 (mean contribution=42.2%) was predominant, followed by BDE-99 (23.1%), BDE-100 (11.9%) and BDE-154 (3.5%). Among the OCs analyzed, $\Sigma$PCBs and $\Sigma$DDTs levels were highest, followed by $\Sigma$HCHs, $\Sigma$CHLs and HCB. The wet weight based $\Sigma$PCBs and $\Sigma$DDTs ranged from 0.28 ng/g to 19.4 ng/g, and from 0.19 ng/g to 4.86 ng/g, respectively. The $\Sigma$PCBs and $\Sigma$DDT slevels in bivalves along the entire Korean coast were lower than those of the USA, and below the Food and Drug Administration (USA. FDA) limits for fish and shell fish. However, the human health criteria and wild life criteria of the USA. Environmental Protection Agency (USA. EPA) were exceeded for DDE and $\Sigma$HCHs at most of the sampling points.