Publications by authors named "Junghyun Lee"

97 Publications

Effect-directed identification of novel aryl hydrocarbon receptor-active aromatic compounds in coastal sediments collected from a highly industrialized area.

Sci Total Environ 2021 Aug 28;803:149969. Epub 2021 Aug 28.

School of Earth and Environmental Sciences, Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea. Electronic address:

In this study, we identified major aryl hydrocarbon receptor (AhR) agonists in the sediments from Yeongil Bay (n = 6) using effect-directed analysis. Using the H4IIE-luc bioassays, great AhR-mediated potencies were found in aromatic fractions (F2) of sediment organic extracts from silica gel column chromatography and sub-fractions (F2.6-F2.8) from reverse phase-HPLC. Full-scan mass spectrometric analysis using GC-QTOFMS was conducted to identify novel AhR agonists in highly potent fractions, such as F2.6-F2.8 of S1 (Gumu Creek). Selection criteria for AhR-active compounds consisted of three steps, including matching factor of NIST library (≥70), aromatic structures, and the number of aromatic rings (≥4). Fifty-nine compounds were selected as tentative AhR agonist candidates, with the AhR-mediated activity being assessed for six compounds for which standard materials were available commercially. Of these compounds, 20-methylcholanthrene, 7-methylbenz[a]anthracene, 10-methylbenz[a]pyrene, and 7,12-dimethylbenz[a]anthracene exhibited significant AhR-mediated potency. Relative potency values of these compounds were determined relative to benzo[a]pyrene to be 3.2, 1.4, 1.2, and 0.2, respectively. EPA positive matrix factorization modeling indicated that the sedimentary AhR-active aromatic compounds primarily originated from coal combustion and vehicle emissions. Potency balance analysis indicated that four novel AhR agonists explained 0.007% to 1.7% of bioassay-derived AhR-mediated potencies in samples.
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http://dx.doi.org/10.1016/j.scitotenv.2021.149969DOI Listing
August 2021

Unsupervised CT Metal Artifact Learning using Attention-guided β-CycleGAN.

IEEE Trans Med Imaging 2021 Jul 30;PP. Epub 2021 Jul 30.

Metal artifact reduction (MAR) is one of the most important research topics in computed tomography (CT). With the advance of deep learning approaches for image reconstruction, various deep learning methods have been suggested for metal artifact reduction, among which supervised learning methods are most popular. However, matched metal-artifact-free and metal artifact corrupted image pairs are difficult to obtain in real CT acquisition. Recently, a promising unsupervised learning for MAR was proposed using feature disentanglement, but the resulting network architecture is so complicated that it is difficult to handle large size clinical images. To address this, here we propose a simple and effective unsupervised learning method for MAR. The proposed method is based on a novel β-cycleGAN architecture derived from the optimal transport theory for appropriate feature space disentanglement. Moreover, by adding the convolutional block attention module (CBAM) layers in the generator, we show that the metal artifacts can be more focused so that it can be effectively removed. Experimental results confirm that we can achieve improved metal artifact reduction that preserves the detailed texture of the original image.
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http://dx.doi.org/10.1109/TMI.2021.3101363DOI Listing
July 2021

Highly efficient and robust noble-metal free bifunctional water electrolysis catalyst achieved via complementary charge transfer.

Nat Commun 2021 Jul 29;12(1):4606. Epub 2021 Jul 29.

Department of Materials Science and Engineering, Perovtronics Research Center, Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea.

The operating principle of conventional water electrolysis using heterogenous catalysts has been primarily focused on the unidirectional charge transfer within the heterostructure. Herein, multidirectional charge transfer concept has been adopted within heterostructured catalysts to develop an efficient and robust bifunctional water electrolysis catalyst, which comprises perovskite oxides (LaSrCoO, LSC) and potassium ion-bonded MoSe (K-MoSe). The complementary charge transfer from LSC and K to MoSe endows MoSe with the electron-rich surface and increased electrical conductivity, which improves the hydrogen evolution reaction (HER) kinetics. Excellent oxygen evolution reaction (OER) kinetics of LSC/K-MoSe is also achieved, surpassing that of the noble metal (IrO), attributed to the enhanced adsorption capability of surface-based oxygen intermediates of the heterostructure. Consequently, the water electrolysis efficiency of LSC/K-MoSe exceeds the performance of the state-of-the-art Pt/C||IrO couple. Furthermore, LSC/K-MoSe exhibits remarkable chronopotentiometric stability over 2,500 h under a high current density of 100 mA cm.
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http://dx.doi.org/10.1038/s41467-021-24829-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8322133PMC
July 2021

Large-scale sediment toxicity assessment over the 15,000 km of coastline in the Yellow and Bohai seas, East Asia.

Sci Total Environ 2021 Oct 10;792:148371. Epub 2021 Jun 10.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea. Electronic address:

The Yellow and Bohai seas have long been contaminated by persistent toxic substances (PTSs) from numerous (un)known anthropogenic sources. In this study, we used Vibrio fischeri bioassay to evaluate ecotoxicological profiles associated with sedimentary PTSs contamination at a large marine ecosystem (LME) scale. A total of 125 surface sediments collected from the coastal areas of the Yellow and Bohai seas were analyzed both for aqueous and organic extracts. Not surprisingly, the results indicated site-dependent toxicities, but most sites were identified as non-toxic to V. fischeri. For aqueous extracts and organic extracts, 13% and 8% of samples, respectively exhibited marginal toxicity, while 0% and 2% of samples exhibited moderate toxicity. However, it should be noted that organic extracts (mean TU = 56) induced stronger toxicities than aqueous samples (mean TU = 0.4). This result generally back-supported the high toxicity potentials associated with sedimentary sink of organic pollutants. Several PTSs measured in the samples indicated a significant contribution to the observed V. fischeri toxicities. Of note, polycyclic aromatic hydrocarbons (PAHs; r = 0.28, p < 0.05), styrene oligomers (r = 0.41, p < 0.01), and alkylphenols (r = 0.38, p < 0.05) showed significant associations to the observed bacterial inhibition. Among PAHs, benzo[a]anthracene and phenanthrene exhibited a significant contribution to the observed V. fischeri toxicities. Meantime, salinity which reflects the distance from the point sources of land-driven pollutants along the rivers and estuaries in the Yellow and Bohai seas was a key environmental variable representing the sample toxicities. Overall, the present study provides baseline information for evaluating the potential sediment toxicity to implement responsible coastal management at an LME scale, and elsewhere.
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http://dx.doi.org/10.1016/j.scitotenv.2021.148371DOI Listing
October 2021

Spatial distribution and source identification of traditional and emerging persistent toxic substances in the offshore sediment of South Korea.

Sci Total Environ 2021 Oct 24;789:147996. Epub 2021 May 24.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea. Electronic address:

While the coastal pollution of persistent toxic substances (PTSs) has been widely documented, information on offshore environments remains limited. Here, we investigated the spatial distribution and sources of PTSs in the offshore sediments (n = 34) of South Korea. Sediment samples collected from the Yellow Sea (n = 18), the South Sea (n = 10), and the East Sea (n = 6), in 2017-18 were analyzed for a total of 71 PTSs. Target compounds include 31 PCBs, 15 PAHs, 9 emerging PAHs (e-PAHs), 10 styrene oligomers (SOs), and 6 alkylphenols (APs). Sedimentary PCBs showed relatively low concentrations with no significant difference across the three seas (0.16-6.9 ng g normalized organic carbon, OC). Low-chlorinated PCBs (tri- and tetra Cl-CBs) were predominant (mean: 77%), primarily indicating atmospheric inputs. PAHs widely accumulated in the three seas with low to moderate level (22-250 ng g OC), and dominated by high molecular weight PAHs (4-6 rings). PMF analysis revealed coast-specific PAHs sources; i.e., originated from mainly coke production (77%) in the Yellow Sea, vehicle emissions (68%) in the South Sea, and fossil fuel combustion (49%) in the East Sea. SOs showed significant contamination than other PTSs, with elevated concentrations in the Yellow Sea (mean: 350 ng g OC). APs showed a similar regional distribution to SOs, but concentrations were much lower (mean: 17 ng g OC). SOs and APs seemed to be introduced from rivers and estuaries on the west coast of Korea, where industrial and municipal activities are concentrated, then might be transported to offshore through tide or currents. Overall, the novel data presented for various PTSs in offshore Korean sediments warrant the necessity of a long-term monitoring effort and urgent management practice to protect marine ecosystem.
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http://dx.doi.org/10.1016/j.scitotenv.2021.147996DOI Listing
October 2021

Novel polar AhR-active chemicals detected in sediments of an industrial area using effect-directed analysis based on in vitro bioassays with full-scan high resolution mass spectrometric screening.

Sci Total Environ 2021 Jul 17;779:146566. Epub 2021 Mar 17.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea. Electronic address:

Studies investigating aryl hydrocarbon receptor (AhR)-active compounds in the environment typically focus on non- and mid-polar substances, such as PAHs; while, information on polar AhR agonists remains limited. Here, we identified polar AhR agonists in sediments collected from the inland creeks of an industrialized area (Lake Sihwa, Korea) using effect-directed analysis combined with full-scan screening analysis (FSA; using LC-QTOFMS). Strong AhR-mediated potencies were observed for the polar and latter fractions of RP-HPLC (F3.5-F3.8) from sediment organic extracts in the H4IIE-luc in vitro bioassays. FSA was performed on the corresponding fractions. Twenty-eight tentative AhR agonists were chosen using a five-step process. Toxicological confirmation using bioassay revealed that canrenone, rutaecarpine, ciprofloxacin, mepanipyrim, genistein, protopine, hydrocortisone, and medroxyprogesterone were significantly active. The relative potencies of these AhR-active compounds compared to that of benzo[a]pyrene ranged from 0.00002 to 2.0. Potency balance analysis showed that polar AhR agonists explained, on average, ~6% of total AhR-mediated potencies in samples. Some novel polar AhR agonists also exhibited endocrine-disrupting potentials capable of binding to estrogen and glucocorticoid receptors, as identified by QSAR modeling. In conclusion, the focused studies on distributions, sources, fate, and ecotoxicological effects of novel polar AhR agonists in the environment are necessary.
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http://dx.doi.org/10.1016/j.scitotenv.2021.146566DOI Listing
July 2021

Psychological Responses Among Korean Middle East Respiratory Syndrome Survivors and Bereaved Families.

Disaster Med Public Health Prep 2021 May 12:1-6. Epub 2021 May 12.

Department of Psychiatry, National Center for Mental Health, Seoul, Republic of Korea.

Objective: In 2015, the outbreak of Middle East Respiratory Syndrome (MERS) in South Korea affected 186 patients and led to 38 bereaved families. This study aimed at investigating the nature and related factors of the psychological responses of MERS victims during the acute phase of disaster.

Methods: The MERS Psychological Support Team under the Korean Ministry of Health and Welfare provided counseling services to MERS survivors and bereaved families for 4 weeks, based on crisis intervention. In this study, we reviewed the counseling records of 109 survivors and 80 bereaved family members, and analyzed their epidemiological and MERS-related information along with psychological responses.

Results: Somatic symptoms and anxiety related to social stigmatization or disease transmission were common in MERS survivors, whereas grief reactions such as sadness, and anger were frequently observed in bereaved families. Bereaved MERS survivors showed more avoidance/isolation than non-bereaved MERS survivors. Females, those with an underlying physical or psychiatric health condition, and those having experienced longer duration of hospitalization and non-healthcare workers were more at risk of suffering from psychological problems.

Conclusions: Survivors and bereaved families of epidemics can experience various psychological distresses depending on individual characteristics and the inherent features of the epidemic. Therefore, mental health in epidemics should be approached and considered more seriously.
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http://dx.doi.org/10.1017/dmp.2021.32DOI Listing
May 2021

Carbon Molecular Sieve Membranes Comprising Graphene Oxides and Porous Carbon for CO/N Separation.

Membranes (Basel) 2021 Apr 12;11(4). Epub 2021 Apr 12.

Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea.

To improve the CO/N separation performance, mixed-matrix carbon molecular sieve membranes (mixed-matrix CMSMs) were fabricated and tested. Two carbon-based fillers, graphene oxide (GO) and activated carbon (YP-50F), were separately incorporated into two polymer precursors (Matrimid 5218 and ODPA-TMPDA), and the resulting CMSMs demonstrated improved CO permeability. The improvement afforded by YP-50F was more substantial due to its higher accessible surface area. Based on the gas permeation data and the Robeson plot for CO/N separation, the performances of the CMSMs containing 15 wt % YP-50F and 15 wt % GO in the mixed polymer matrix surpassed the 2008 Robeson upper bound of polymeric membranes. Hence, this study demonstrates the feasibility of such membranes in improving the CO/N separation performance through the appropriate choice of carbon-based filler materials in polymer matrices.
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http://dx.doi.org/10.3390/membranes11040284DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8069981PMC
April 2021

High-Crystalline Monolayer Transition Metal Dichalcogenides Films for Wafer-Scale Electronics.

ACS Nano 2021 Feb 29;15(2):3038-3046. Epub 2021 Jan 29.

Department of Materials Science and Engineering, Perovtronics Research Center, Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.

Chemical vapor deposition (CVD) using liquid-phase precursors has emerged as a viable technique for synthesizing uniform large-area transition metal dichalcogenide (TMD) thin films. However, the liquid-phase precursor-assisted growth process typically suffers from small-sized grains and unreacted transition metal precursor remainders, resulting in lower-quality TMDs. Moreover, synthesizing large-area TMD films with a monolayer thickness is also quite challenging. Herein, we successfully synthesized high-quality large-area monolayer molybdenum diselenide (MoSe) with good uniformity via promoter-assisted liquid-phase CVD process using the transition metal-containing precursor homogeneously modified with an alkali metal halide. The formation of a reactive transition metal oxyhalide and reduction of the energy barrier of chalcogenization by the alkali metal promoted the growth rate of the TMDs along the in-plane direction, enabling the full coverage of the monolayer MoSe film with negligible few-layer regions. Note that the fully selenized monolayer MoSe with high crystallinity exhibited superior electrical transport characteristics compared with those reported in previous works using liquid-phase precursors. We further synthesized various other monolayer TMD films, including molybdenum disulfide, tungsten disulfide, and tungsten diselenide, to demonstrate the broad applicability of the proposed approach.
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http://dx.doi.org/10.1021/acsnano.0c09430DOI Listing
February 2021

Implementation of ISO45001 Considering Strengthened Demands for OHSMS in South Korea: Based on Comparing Surveys Conducted in 2004 and 2018.

Saf Health Work 2020 Dec 11;11(4):418-424. Epub 2020 Sep 11.

Department of Health Science, Korea University, Anam-ro 145, Seongbuk-gu, Seoul, 02841, Republic of Korea.

Background: According to the previous studies, the work-related accident rate decreased in Korea after the introduction of occupational health and safety management system (OHSMS), but there were several disasters in Korea such as subway worker's death at Guui station in 2016 and the Taean thermal power plant accident in 2018, which escalated the social demand for safety. In 2018, OHSMS became an international standard, as ISO45001 was announced.

Methods: A survey was conducted to research the implementation status of OHSMS and changes in people's perception, and the results were compared with those of a past survey.

Results: Enhanced social demand and various stakeholders' (not only buyer) needs, and social responsibility are perceived as the motivation for the introduction of OHSMS rather than legal compliance or customer demand. In the questionnaire about problems with the implementation of OHSMS, the factors with higher response rate in 2018 than 2004 were "excessive cost" and "complicated documentation management." In the questionnaire about how to promote OHSMS in organizations, most people answered "reduction of workers' compensation insurance rate" in 2004, but most people answered "exemption from health and safety supervision" in 2018.

Conclusion: For the effective implementation of ISO45001, emphasis is placed on social demand, training to recognize health and safety as a part of management, and the reduction of certification and consulting costs to promote the introduction of OHSMS. Incentives such as insurance premium cuts and exemptions from health and safety supervision are needed.
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http://dx.doi.org/10.1016/j.shaw.2020.08.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7728702PMC
December 2020

Defect-Induced Atomic Doping in Transition Metal Dichalcogenides via Liquid-Phase Synthesis toward Efficient Electrochemical Activity.

ACS Nano 2020 Dec 7. Epub 2020 Dec 7.

Department of Materials Science and Engineering, Perovtronics Research Center, Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.

Transition metal dichalcogenides (TMDs), due to their fascinating properties, have emerged as potential next-generation semiconducting nanomaterials across diverse fields of applications. When combined with other material systems, precise control of the intrinsic properties of the TMDs plays a vital role in maximizing their performance. Defect-induced atomic doping through introduction of a chalcogen vacancy into the TMDs lattices is known to be a promising strategy for modulating their characteristic properties. As a result, there is a need to develop tunable and scalable synthesis routes to achieve vacancy-modulated TMDs. Herein, we propose a facile liquid-phase ligand exchange approach for scalable, uniform, and vacancy-tunable synthesis of TMDs films. Varying the relative molar ratio of the chalcogen to transition metal precursors enabled the modulation of the chalcogen vacancy concentrations without necessitating additional post-treatments. When employed as the electrocatalyst in the hydrogen evolution reaction (HER), the vacancy-modulated TMDs, exhibiting a synergetic effect on the energy level matching to the reduction potential of water and optimized free energy differences in the HER pathways, showed a significant enhancement in the hydrogen production the improved charge transfer kinetics and increased active sites. The proposed approach for synthesizing tunable vacancy-modulated TMDs with wafer-scale synthesis capability is, therefore, promising for better practical applications of TMDs.
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http://dx.doi.org/10.1021/acsnano.0c06783DOI Listing
December 2020

Macrozoobenthic community responses to sedimentary contaminations by anthropogenic toxic substances in the Geum River Estuary, South Korea.

Sci Total Environ 2021 Apr 16;763:142938. Epub 2020 Oct 16.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea. Electronic address:

We investigated the sedimentary pollution by persistent toxic substances (PTSs) and their potential impacts on the macrobenthic faunal community in the Geum River Estuary, South Korea. Sediment and benthic macrofauna samples were collected from eight sites every two months during the period of February to December in 2015. Target PTSs encompassed metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn), one metalloid (As), polycyclic aromatic hydrocarbons (PAHs), and alkylphenols (APs). The significant difference to the environment of the inner and outer parts of the estuary (p < 0.05) was found with relatively high concentrations of PTSs in sediment from the inner estuary. The concentrations of Cu and Zn exceeded the sediment quality guidelines of Korea representing a potential risk to aquatic organisms. The primary source of PAHs was by-products of diesel and gasoline combustion (37%), followed by a coke oven (32%) and oil-burning (31%). The macrofaunal community was spatially distinguished between the inner and outer parts of the estuary (p < 0.05), regardless of the season. In the inner part of the estuary, the density of the macrofaunal community was high, due to the increased opportunistic species and/or some indicator species (organic polluted or enrichment), implying that the given environment was disturbed. Among the environmental parameters analyzed by the distance-based linear model (DistLM), salinity, chlorophyll-a, and nutrient concentrations were found to be key factors controlling the changes in macrofaunal community structure. Such changes in the closed estuary system would indicate that each taxonomic group had to adjust to lower salinities and alternative food sources. Overall, the distribution of PTSs and macrozoobenthic communities in the Geum River Estuary collectively reflected the environmental gradients caused by surrounding activities in the inner part of the estuary together with direct effects by the irregular inflow of freshwater.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142938DOI Listing
April 2021

Identification of potential toxicants in sediments from an industrialized area in Pohang, South Korea: Application of a cell viability assay of microalgae using flow cytometry.

J Hazard Mater 2021 03 10;405:124230. Epub 2020 Oct 10.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea. Electronic address:

Potential toxicants in sediments collected from an industrialized bay of Korea were identified by use of effect-directed analysis (EDA). Three marine microalgal bioassays (Dunaliella tertiolecta, Isochrysis galbana, and Phaeodactylum tricornutum) with diverse endpoints were employed. Initial screening of raw organic extracts of sediments indicated large variations among locations and species in a traditional endpoint "inhibition of growth". After fractionation, inhibition of growths increased significantly, particularly in some fractions containing aromatics with log K 5-6 (F2.6). While viabilities of cells were adversely affected in more fractions, including F2.6-F2.7 (log K 5-7) and F3.5-F3.6 (log K 4-6). Among the several endpoints of viability, esterase activity seemed to be more sensitive, followed by integrity of cell membranes, chlorophyll a, cell size, and intracellular complexity. Instrumental analyses indicated that toxicities to microalgae observed in F2.7 could not be fully explained by target PAHs. Full-scan screening analysis using GC-QTOFMS identified 58 compounds in F2.7 with matching scores ≥90%. Based on toxic potencies for these compounds predicted by ECOSAR, several causative agents, including 1-phenylpyrene, dibenz[a,c]anthracene, and picene were suggested. Overall, viability of microalgae provided sensitive and high-resolution toxicity screening of samples into integrative assessment of sediment.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124230DOI Listing
March 2021

Postoperative Chylothorax after Modified Radical Neck Dissection for Thyroid Carcinoma: A Missable Rare Complication of Thyroid Surgery.

Medicina (Kaunas) 2020 Sep 21;56(9). Epub 2020 Sep 21.

Cancer research institute, Seoul National University College of Medicine, Seoul 10408, Korea.

: Currently, few studies have been conducted on postoperative chylothorax, specifically in total thyroidectomy with modified radical neck dissection (MRND) in papillary thyroid carcinoma patients. This study provides the actual incidence, etiology, and clinical features of postoperative chylothorax and reports the clinical outcomes after treatment, which were dependent upon the severity of the complications. : The medical charts of 111 papillary thyroid cancer (PTC) patients who underwent total thyroidectomy with modified radical neck dissection from January 2016 to December 2018 were reviewed retrospectively. The results were compared in three groups: the no chylothorax group, the subclinical (asymptomatic) group, and the clinical (symptomatic) group. Chylothorax occurred in 23 patients (20.7%, 23/111). Nineteen (82.6%, 19/23) were subclinical chylothorax cases, which implies a small amount of chyle leakage with no respiratory symptoms. Four (17.4%, 4/23) were clinical, meaning they had either respiratory symptoms, such as dyspnea, desaturation, or a large amount of chylothorax in the images. The incidence was significantly higher in patients who underwent left modified radical neck dissection, and this corresponds to the side in which chylothorax occurred. There were also statistical differences in the drainage color, peak amount, or drain removal time. Postoperative chylothorax is a rare complication following neck dissection. However, it can be fatal if the condition progresses. Therefore, patients who undergo total thyroidectomy with modified radical neck dissection, especially on the left side, should be monitored for respiratory symptoms, and serial chest x-ray images obtained.
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http://dx.doi.org/10.3390/medicina56090481DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7557742PMC
September 2020

Characteristics of long-term changes in microbial communities from contaminated sediments along the west coast of South Korea: Ecological assessment with eDNA and physicochemical analyses.

Mar Pollut Bull 2020 Nov 11;160:111592. Epub 2020 Sep 11.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea. Electronic address:

The environmental DNA (eDNA) metabarcoding was applied to assess benthic ecological health in the west coast of South Korea by investigating a long-term microbial community change (2015-17). The ecological interaction among microorganisms, from phylum to family level, and their associations to environmental variables across the five regions were highlighted. As part of the study, the available chemistry and toxicological data in the regions during the monitoring periods were incorporated into an integrated sediment triad assessment. The bacterial communities were dominated by Proteobacteria (34.2%), Bacteroidetes (13.8%), and Firmicutes (10.8%). Proteobacteria and Bacteroidetes dominated consistently across regions and years, while Firmicutes and Cyanobacteria significantly varied by region and years (p < 0.05). The abundance of this phylum declined over time with the increasing abundance of Cyanobacteria, indicating their independent interactions to certain environmental changes. Planctomycetes and Gemmatimonadetes linked to some contaminants (ΣPAHs and Cu), implying indicator taxa. Overall, eDNA-based microbial community analysis combined with exposures of contaminants and responses of microorganisms is a promising strategy for the assessment of benthic ecological health in contaminated sediments from coastal waters.
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http://dx.doi.org/10.1016/j.marpolbul.2020.111592DOI Listing
November 2020

Influence of ligand's directional configuration, chrysenes as model compounds, on the binding activity with aryl hydrocarbon receptor.

Sci Rep 2020 08 14;10(1):13821. Epub 2020 Aug 14.

School of Earth and Environmental Sciences and Research Institute of Oceanography, Seoul National University, Seoul, Republic of Korea.

Understanding what and how physico-chemical factors of a ligand configure conditions for ligand-receptor binding is a key to accurate assessment of toxic potencies of environmental pollutants. We investigated influences of the dipole-driven orientation and resulting directional configuration of ligands on receptor binding activities. Using physico-chemical properties calculated by ab initio density functional theory, directional reactivity factors (DRF) were devised as main indicators of toxic potencies, linking molecular ligand-receptor binding to in vitro responses. The directional reactive model was applied to predict variation of aryl hydrocarbon receptor-mediated toxic potencies among homologues of chrysene with structural modifications such as the numbers of constituent benzene rings, methylation and hydroxylation. Results of predictive models were consistent with empirical potencies determined by use of the H4IIE-luc transactivation bioassay. The experiment-free approach based on first principles provides an analytical framework for estimating molecular bioactivity in silico and complements conventional empirical approaches to studying molecular initiating events in adverse outcome pathways.
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http://dx.doi.org/10.1038/s41598-020-70704-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7428016PMC
August 2020

CO/N Separation Properties of Polyimide-Based Mixed-Matrix Membranes Comprising UiO-66 with Various Functionalities.

Membranes (Basel) 2020 Jul 17;10(7). Epub 2020 Jul 17.

Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea.

Nanocrystalline UiO-66 and its derivatives (containing -NH, -Br, -(OH)) were developed via pre-synthetic functionalization and incorporated into a polyimide membrane to develop a mixed-matrix membrane (MMM) for CO/N separation. Incorporation of the non-functionalized UiO-66 nanocrystals into the polyimide membrane successfully improved CO permeability, with a slight decrease in CO/N selectivity, owing to its large accessible surface area. The addition of other functional groups further improved the CO/N selectivity of the polymeric membrane, with UiO-66-NH, UiO-66-Br, and UiO-66-(OH) demonstrating improvements of 12%, 4%, and 17%, respectively. Further evaluation by solubility-diffusivity analysis revealed that the functionalized UiO-66 in MMMs can effectively increase CO diffusivity while suppressing N sorption, thus, resulting in improved CO/N selectivity. Such results imply that the structural tuning of UiO-66 by the incorporation of various functional groups is an effective strategy to improve the CO separation performance of MMMs.
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http://dx.doi.org/10.3390/membranes10070154DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7407110PMC
July 2020

Phase Engineering of Transition Metal Dichalcogenides with Unprecedentedly High Phase Purity, Stability, and Scalability via Molten-Metal-Assisted Intercalation.

Adv Mater 2020 Aug 6;32(33):e2001889. Epub 2020 Jul 6.

Department of Energy Engineering, School of Energy and Chemical Engineering, Low Dimensional Carbon Materials Center, Perovtronics Research Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.

The crystalline phase of layered transition metal dichalcogenides (TMDs) directly determines their material property. The most thermodynamically stable phase structures in TMDs are the semiconducting 2H and metastable metallic 1T phases. To overcome the low phase purity and instability of 1T-TMDs, which limits the utilization of their intrinsic properties, various synthesis strategies for 1T-TMDs have been proposed in phase-engineering studies. Herein, a facile and scalable synthesis of 1T-phase molybdenum disulfide (MoS ) via the molten-metal-assisted intercalation (MMI) approach is introduced, which exploits the capillary action of molten potassium and the difference between the electron affinity of MoS and the ionization potential of potassium. Highly reactive molten potassium metal can readily intercalate into the MoS interlayers, inducing an efficient phase transition from the 2H to 1T crystal structure. The ionic bonding between the intercalated potassium and sulfur lowers the energy barrier of the 1T-phase transition, enhancing the phase stability of the 1T crystals. Owing to the high purity and stability of the 1T phase, the electrocatalytic performance for the hydrogen evolution reaction is significantly higher in 1T-MoS (MMI) than in 2H-MoS and even in 1T-MoS synthesized using n-butyllithium.
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http://dx.doi.org/10.1002/adma.202001889DOI Listing
August 2020

Lithiation Mechanism Change Driven by Thermally Induced Grain Fining and Its Impact on the Performance of LiMn O in Lithium-Ion Batteries.

Small 2020 Jul 18;16(29):e2002292. Epub 2020 Jun 18.

Department of Bionano Technology, Hanyang University, Ansan, Gyeonggi-do, 15588, Republic of Korea.

The nature of precursors employed in the synthesis of lithium-ion battery cathode materials is a crucial performance-dictating factor. Therefore, it is of great importance to establish a way to manipulate the precursor and seek a comprehensive understanding of its influence on the electrochemical behavior of a targeted electrode material. A thermal route is herein demonstrated for the synthesis of lithium-excess LiMn O (LMO) by exploiting an intriguing thermal phenomenon, thermally induced grain fining, and sheds light on how it affects the mechanism and kinetics of lithiation, and, furthermore, the electrochemical behavior of LMO. Detailed insights into the lithiation mechanism and kinetics reveal that the use of a finely grained, porous Mn O , which possesses an open crystal structure, is a key to the success of incorporating excess Li. In addition, this in-depth electrochemical investigation verifies a very recent theoretical prediction of faster Li diffusion kinetics enabled by excess Li.
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http://dx.doi.org/10.1002/smll.202002292DOI Listing
July 2020

Suppressed Interdiffusion and Degradation in Flexible and Transparent Metal Electrode-Based Perovskite Solar Cells with a Graphene Interlayer.

Nano Lett 2020 May 2;20(5):3718-3727. Epub 2020 Apr 2.

Department of Energy Engineering, School of Energy and Chemical Engineering, Low Dimensional Carbon Materials Center, Perovtronics Research Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.

Metal-based transparent conductive electrodes (TCEs) are attractive candidates for application in indium tin oxide (ITO)-free solar cells due to their excellent electrical conductivity and cost effectiveness. In perovskite solar cells (PSCs), metal-induced degradation with the perovskite layer leads to various detrimental effects, deteriorating the device performance and stability. Here, we introduce a novel flexible hybrid TCE consisting of a Cu grid-embedded polyimide film and a graphene capping layer, named GCEP, which exhibits excellent mechanical and chemical stability as well as desirable optoelectrical properties. We demonstrated the critical role of graphene as a protection layer to prevent metal-induced degradation and halide diffusion between the electrode and perovskite layer; the performance of the flexible PSCs fabricated with GCEP was comparable to that of their rigid ITO-based counterparts and also exhibited outstanding mechanical and chemical stability. This work provides an effective strategy to design mechanically and chemically robust ITO-free metal-assisted TCE platforms in PSCs.
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http://dx.doi.org/10.1021/acs.nanolett.0c00663DOI Listing
May 2020

Multiple Bioassays and Targeted and Nontargeted Analyses to Characterize Potential Toxicological Effects Associated with Sediments of Masan Bay: Focusing on AhR-Mediated Potency.

Environ Sci Technol 2020 04 23;54(7):4443-4454. Epub 2020 Mar 23.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea.

An enhanced, multiple lines of evidence approach was applied to assess potential toxicological effects associated with polluted sediments. Two in vitro bioassays (H4IIE- and ) and three in vivo bioassays (microalgae: and ; zebrafish embryo: ) were applied. To identify causative chemicals in samples, targeted analyses (polycyclic aromatic hydrocarbons (PAHs), styrene oligomers (SOs), and alkylphenols) and nontargeted full-scan screening analyses (FSA; GC- and LC-QTOFMS) were performed. First, great AhR-mediated potencies were observed in midpolar and polar fractions of sediment extracts, but known and previously characterized AhR agonists, including PAHs and SOs could not fully explain the total potencies of samples. Enoxolone was identified as a novel AhR agonist in a highly potent sediment fraction by use of FSA. Enoxolone has a relative potency of 0.13 compared to benzo[]pyrene (1.0) in the H4IIE- bioassay. Nonylphenols associated with membrane damage that influenced the viability of the microalgae were also observed. Finally, inhibitions of bioluminescence of and lethality of embryos were strongly related to nonpolar compounds. Overall, the present work addressed assay- and end point-specific variations and sensitivities for potential toxicities of mixture samples, warranting a significant utility of the "multiple lines of evidence" approach in ecological risk assessment.
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http://dx.doi.org/10.1021/acs.est.9b07390DOI Listing
April 2020

Integrated assessment of west coast of South Korea by use of benthic bacterial community structure as determined by eDNA, concentrations of contaminants, and in vitro bioassays.

Environ Int 2020 04 18;137:105569. Epub 2020 Feb 18.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea. Electronic address:

During the past few decades, contamination of sediments by persistent toxic substances (PTSs) has been observed in estuarine and coastal areas on the west coast of South Korea. The contaminants are suspected to cause toxicities in aquatic biota, but little is known about their ecological effects, particularly on benthic microbial communities. In this study, an eDNA-based assessment was applied along with classic assessments of exposure, such as chemistry and in vitro bioassays, to evaluate condition of benthic bacterial communities subjected to PTSs. Two strategies were adopted for the study. One was to conduct a comprehensive assessment in space (by comparing seawater and freshwater sites at five coastal regions) and in time (by following change over a 5-y period). Although we found that bacterial composition varied among and within years, some phyla, such as Proteobacteria (28.7%), Actinobacteria (13.1%), Firmicutes (12.7%), and Chloroflexi (12.5%) were consistently dominated across the study regions. Certain bacterial groups, such as Firmicutes and Verrucomicrobia have been linked to contamination at some sites in the study area and at specific points in time. Bacterial communities were not significantly correlated with salinity or AhR- and ER-mediated potencies, whereas concentrations of PAHs, APs, and certain metals (Cd and Hg) exhibited significant associations to the structure of bacterial communities at the phylum level. In fact, the relative abundance of microbes in the phylum Planctomycetes was significantly and negatively correlated with concentrations of PAHs and metals. Thus, the relative abundance of Planctomycetes could be used as an indicator of sedimentary contamination by PAHs and/or metals. Based on our correlation analyses, Cd and ER-mediated potencies were associated more with bacterial abundances at the class taxonomic level than were other PTSs and metals. Overall, the eDNA-based assessment was useful by augmenting more traditional measures of exposure and responses in a sediment triad approach and has potential as a more rapid screening tool.
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http://dx.doi.org/10.1016/j.envint.2020.105569DOI Listing
April 2020

The relationship between metabolic syndrome and the incidence of colorectal cancer.

Environ Health Prev Med 2020 Feb 19;25(1). Epub 2020 Feb 19.

Department of Nursing, College of Nursing, Konyang University, Daejeon, Korea.

Objectives: This study evaluated the incidence of colorectal cancer (CRC) according to the number of metabolic syndrome (MetS) components.

Methods: Using health checkup and insurance claims data of 6,365,409 subjects, the occurrence of CRC according to stage of MetS by sex was determined from the date of the health checkup in 2009 until December 31, 2018.

Results: Cumulative incidence rates (CIR) of CRC in men and women was 3.9 and 2.8 per 1000 (p < 0.001), respectively. CIR of CRC for the normal, pre-MetS, and MetS groups in men was 2.6, 3.9, and 5.5 per 1000 (p < 0.001) and CIR in women was 2.1, 2.9, and 4.5 per 1000 (p < 0.001), respectively. Compared with the normal group, the hazard ratio (HR) of CRC for the pre-MetS group was 1.25 (95% CI 1.17-1.33) in men and 1.09 (95% CI 1.02-1.17) in women, and the HR of CRC for the MetS group was 1.54 (95% CI 1.43-1.65) in men and 1.39 (95% CI 1.26-1.53) in women after adjustment.

Conclusions: We found that MetS is a risk factor for CRC in this study. Therefore, the prevention and active management of MetS would contribute to the prevention of CRC.
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http://dx.doi.org/10.1186/s12199-020-00845-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7031951PMC
February 2020

Zwitterionic Conjugated Surfactant Functionalization of Graphene with pH-Independent Dispersibility: An Efficient Electron Mediator for the Oxygen Evolution Reaction in Acidic Media.

Small 2020 03 19;16(11):e1906635. Epub 2020 Feb 19.

Department of Energy Engineering, School of Energy and Chemical Engineering, Low Dimensional Carbon Materials Center, Perovtronics Research Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.

The functionalization of graphene has been extensively used as an effective route for modulating the surface property of graphene, and enhancing the dispersion stability of graphene in aqueous solutions via functionalization has been widely investigated to expand its use for various applications across a range of fields. Herein, an effective approach is described for enhancing the dispersibility of graphene in aqueous solutions at different pH levels via non-covalent zwitterion functionalization. The results show that a surfactant with electron-deficient carbon atoms in its backbone structure and large π-π interactive area enables strong interactions with graphene, and the zwitterionic side terminal groups of the molecule support the dispersibility of graphene in various pH conditions. Experimental and computational studies confirm that perylene diimide amino N-oxide (PDI-NO) allows efficient functionalization and pH-independent dispersion of graphene enabled by hydration repulsion effects induced by PDI-NO. The PDI-NO functionalized graphene is successfully used in the oxygen evolution reaction as an electron mediator for boosting the electrocatalytic activity of a Ru-based polyoxometalate catalyst in an acidic medium. The proposed strategy is expected to bring significant advances in producing highly dispersible graphene in aqueous medium with pH-independent stability, thus broadening the application range of graphene.
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http://dx.doi.org/10.1002/smll.201906635DOI Listing
March 2020

Long-term trends of persistent toxic substances and potential toxicities in sediments along the west coast of South Korea.

Mar Pollut Bull 2020 Feb 29;151:110821. Epub 2020 Jan 29.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea. Electronic address:

For decades, in response to industrialization and urbanization, environmental qualities of estuarine and coastal areas of the west coast of Korea have been deteriorating. Long-term changes in concentrations of persistent toxic substances (PTSs) in sediments, including PAHs, styrene oligomers, nonylphenols, and metals and their potential toxicities via AhR- and ER-mediated potencies, and bioluminescent bacterial inhibition, were investigated. Long-term monitoring in five estuarine and coastal areas (2010-2018; 10 sites) showed that concentrations of PAHs and nonylphenols in sediments have declined while concentrations of some metals, Cd, Cr, and Hg have increased. Similarly, AhR-mediated potencies in sediments have declined, but inhibitions of bioluminescent bacteria have increased. Concentrations of sedimentary PAHs and AhR-mediated potencies were significantly (p < 0.01) and positively correlated. Sources of PAHs from combustion have been gradually declining while inputs from vehicle exhaust by-products have been increasing. Overall, this study brought our attention a balanced regulation in chemical-specific manner.
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http://dx.doi.org/10.1016/j.marpolbul.2019.110821DOI Listing
February 2020

Ultrasensitive Plasmon-Free Surface-Enhanced Raman Spectroscopy with Femtomolar Detection Limit from 2D van der Waals Heterostructure.

Nano Lett 2020 Mar 7;20(3):1620-1630. Epub 2020 Feb 7.

Department of Energy Engineering, School of Energy and Chemical Engineering, Low Dimensional Carbon Materials Center, Perovtronics Research Center, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.

Two-dimensional (2D) materials have been promoted as an ideal platform for surface-enhanced Raman spectroscopy (SERS), as they mitigate the drawbacks of noble metal-based SERS substrates. However, the inferior limit of detection has limited the practical applicability of 2D material-based SERS substrates. Here, we synthesize uniform large-area ReOS thin films via solution-phase deposition without post-treatments and demonstrate a graphene/ReOS vertical heterostructure as an ultrasensitive SERS platform. The electronic structure of ReOS can be modulated by changing the oxygen concentration in the lattice structure, obtaining efficient complementary resonance effects between ReOS and the probe molecule. In addition, the oxygen atoms in the ReOS lattice generate a dipole moment on the thin-film surface, which increases the electron transition probability. These synergistic effects outstandingly enhance the Raman effect in the ReOS thin film. When ReOS forms a vertical heterostructure on a graphene as the SERS substrate, the enhanced charge-transfer and exciton resonances improve the limit of detection to the femtomolar level, while achieving remarkable flexibility, reproducibility, and operational stability. Our results provide important insights into 2D material-based ultrasensitive SERS based on chemical mechanisms.
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http://dx.doi.org/10.1021/acs.nanolett.9b04645DOI Listing
March 2020

Major AhR-active chemicals in sediments of Lake Sihwa, South Korea: Application of effect-directed analysis combined with full-scan screening analysis.

Environ Int 2019 12 29;133(Pt B):105199. Epub 2019 Oct 29.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea.

This study utilized effect-directed analysis (EDA) combined with full-scan screening analysis (FSA) to identify aryl hydrocarbon receptor (AhR)-active compounds in sediments of inland creeks flowing into Lake Sihwa, South Korea. The specific objectives were to (i) investigate the major AhR-active fractions of organic extracts of sediments by using H4IIE-luc in vitro bioassay (4 h and 72 h exposures), (ii) quantify known AhR agonists, such as polycyclic aromatic hydrocarbons (PAHs) and styrene oligomers (SOs), (iii) identify unknown AhR agonists by use of gas chromatography-quadrupole time-of-flight mass spectrometry (GC-QTOFMS), and (iv) determine contributions of AhR agonists to total potencies measured by use of the bioassay. FSA was conducted on fractions F2.6 and F2.7 (aromatics with log K 5-7) in extracts of sediment from Siheung Creek (industrial area). Those fractions exhibited significant AhR-mediated potency as well as relatively great concentrations of PAHs and SOs. FSA detected 461 and 449 compounds in F2.6 and F2.7, respectively. Of these, five tentative candidates of AhR agonist were selected based on NIST library matching, aromatic structures and numbers of rings, and available standards. Benz[b]anthracene, 11H-benzo[a]fluorene, and 4,5-methanochrysene exhibited significant AhR-mediated potency in the H4IIE-luc bioassay, and relative potencies of these compounds were determined. Potency balance analysis demonstrated that these three newly identified AhR agonists explained 1.1% to 67% of total induced AhR-mediated potencies of samples, which were particularly great for industrial sediments. Follow-up studies on sources and ecotoxicological effects of these compounds in coastal environments would be required.
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http://dx.doi.org/10.1016/j.envint.2019.105199DOI Listing
December 2019

Multifaceted Role of a Dibutylhydroxytoluene Processing Additive in Enhancing the Efficiency and Stability of Planar Perovskite Solar Cells.

ACS Appl Mater Interfaces 2019 Oct 9;11(42):38828-38837. Epub 2019 Oct 9.

Significant research efforts are currently being devoted to improving both the crystalline quality and stability of lead halide perovskite absorbers to advance the commercial prospects of perovskite-based solar cells. Herein, we report a simple one-step dibutylhydroxytoluene (BHT) additive-based approach for simultaneously improving the crystallinity and resistance of perovskite films under adverse degradation conditions. We found that BHT, commonly known for its antioxidant properties, can considerably improve the performance of methylammonium lead iodide perovskite solar cells by modulating the chemical environment within the precursor medium to form intermediate complexes, and it can also suppress photooxidation, which results in perovskite degradation under environmental operating conditions. Consequently, a device exhibited a significant power conversion efficiency improvement to 18.1% with the BHT-additive-based perovskite absorber, exceeding the 17.1% efficiency achieved for the control device. The BHT additive also improved the perovskite stability by quenching intermediate reactions resulting in perovskite degradation to an undesirable lead iodide phase, as evidenced by detailed analysis of absorption spectra, grazing-incidence wide-angle X-ray scattering, X-ray photoelectron spectra, and photoluminescence measurements.
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http://dx.doi.org/10.1021/acsami.9b14423DOI Listing
October 2019

Multiple evaluation of the potential toxic effects of sediments and biota collected from an oil-polluted area around Abu Ali Island, Saudi Arabia, Arabian Gulf.

Ecotoxicol Environ Saf 2019 Nov 10;183:109547. Epub 2019 Aug 10.

School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, Republic of Korea. Electronic address:

After the Gulf War Oil Spill, there have been many investigations about distributions of oil-derived pollutants nearby areas, but lacking in ecotoxicological assessment. We evaluated the potential toxicity of asphalt mats, sediments, and biota (polychaetes, chitons, snapping shrimps, and crabs) by combining two bioassays (H4IIE-luc and Vibrio fischeri) and in situ microbial community (eDNA). Samples were collected from Abu Ali Island, and organic extracts were bioassayed and further fractionated according to the chemical polarity using silica gel column. Great aryl hydrocarbon receptor (AhR)-mediated potencies and inhibition of bioluminescence were mainly found in aromatics (F2) and saturates (F1) fractions of asphalt mat and sediments, respectively, while great toxicological responses in biota samples were found in resins and polar (F3) fraction. We also confirmed that potential toxicities of biota were species-specific; great AhR-mediated potencies were found in polychaetes and great bioluminescence inhibitions were found in crabs. In microbial communities, most genera (up to 90%) were associated with polycyclic aromatic hydrocarbons (PAHs)-degrading bacteria, supporting that PAHs are the primary stressors of the benthic community around Abu Ali Island. The present study provides useful information on the contamination status, risk assessment of environmental matrices and benthic organisms in Abu Ali Island.
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http://dx.doi.org/10.1016/j.ecoenv.2019.109547DOI Listing
November 2019

Newly Identified AhR-Active Compounds in the Sediments of an Industrial Area Using Effect-Directed Analysis.

Environ Sci Technol 2019 Sep 1;53(17):10043-10052. Epub 2019 Aug 1.

School of Earth and Environmental Sciences & Research Institute of Oceanography , Seoul National University , Seoul 08826 , Republic of Korea.

Effect-directed analysis was used to identify previously unidentified aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area of Ulsan Bay, Korea. The specific objectives were to (i) investigate potent fractions of sediment extracts using the H4IIE- bioassay, (ii) determine the concentrations of known AhR agonists (polycyclic aromatic hydrocarbons (PAHs) and styrene oligomers (SOs)), (iii) identify previously unreported AhR agonists in fractions by use of GC-QTOFMS, and (iv) evaluate contributions of individual compounds to overall AhR-mediated potencies, found primarily in fractions containing aromatics with log 5-8. Greater concentrations of PAHs and SOs were also found in those fractions. On the basis of GC-QTOFMS and GC-MSD analyses, 16 candidates for AhR agonists were identified in extracts of sediments. Of these, seven compounds, including 1-methylchrysene, benzo[]fluoranthene, 3-methylchrysene, 5-methylbenz[]anthracene, 11-benzo[]fluorene, benzo[]naphtho[2,3-]furan, and benzo[]naphtho[2,1-]thiophene, exhibited significant AhR activity. Relative potency values of newly identified AhR agonists were found to be greater than or comparable to that of benzo[]pyrene (BaP). The potency balance analysis showed that newly identified AhR agonists explained 0.07-16% of bioassay-derived BaP-EQs. These chemicals were widely distributed in industrial sediments; thus, it is of immediate importance to conduct studies on sources and potential effects of those chemicals.
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http://dx.doi.org/10.1021/acs.est.9b02166DOI Listing
September 2019
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