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The impacts of natural dimethyl sulfide (DMS) and ship emissions on marine environments and particulate matter (PM) over the western and southern sea areas around South Korea were studied based on field campaigns from August-September 2017 and May-June 2018 using the Community Multi-scale Air Quality v5.3.2 modeling system. DMS oxidation enhanced the concentrations of both sulfur dioxide (SO 2 ) and sulfate (SO 4 2- ) in PM 2.5 by 6.2-6.4% and 2.9-3.6%, respectively, in the marine atmosphere during the study period, whereas it slightly decreased nitrate (NO 3 - ) concentrations (by -1.3%), compared to the simulation without DMS oxidation chemistry. Furthermore, ship emissions increased the concentrations of SO 4 2- , NO 3 - , and NH 4 + by 4.5%, 23%, and 7.3%, respectively. Methane sulfonic acid concentration was 0.17 μg m -3 , suggesting the importance of the addition channel in the DMS oxidation pathway. The model simulation indicated that ship emissions in the target area contributed dominantly to non-sea-salt SO 4 2- , and the marine DMS emission source was non-negligible. The geographical distribution of PM toxicity (aerosol oxidative potential) was assessed in the marine atmosphere during the study period., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Large-scale Sargassum blooms have been increasingly observed in coastal zones in recent years. Sargassum horneri (Turner) C. Agardh blooms (pelagic) have been observed in Jeju Island (Korea) and the southwest of the Korean Peninsula, causing serious problems for seaweed and abalone farms as well as for fisheries, tourism and recreational industries. The present study explored the physiological responses of attached and pelagic S. horneri populations cultivated under different nutrient concentrations (HN: 50 μM of nitrogen and 5 μM of phosphorus; LN: 5 μM of nitrogen and 0.5 μM of phosphorus) and photosynthetically active radiation (PAR) (H-PAR: 250; M-PAR: 150; L-PAR: 50 μmol photons m -2 s -1 ) for 25 days. Relative growth rates (RGR) were significantly lower in the pelagic population than that in the attached population. All thalli from the pelagic population died within 20 days. Chlorophyll a and c, and carotenoids were significantly higher at HN than at LN, and decreased as PAR increased for both populations. For the attached population, photosynthetic rate, tissue nitrogen, and carbon and nitrogen removal were also significantly higher at HN than at LN. These results suggest that high nutrient and lower PAR increased the biomass accumulation of attached populations in coastal areas. Nutrient limitation and high PAR may accelerate senescence of the pelagic populations while traveling on the sea surface from their point of origin., (Copyright © 2021. Published by Elsevier Ltd.)

We investigated spatiotemporal distributions of dissolved inorganic nutrients and organic carbon (DOC) and nitrogen (DON) in coastal waters and land-based fish farm wastewater to determine effects of wastewater on seawater of Jeju Island, Korea. The nutrient concentrations in seawater were lower than in wastewater with negative correlations against salinity, indicating a terrestrial source. Wastewater-derived DOC and DON were transported offshore while wastewater-derived inorganic nutrients were effectively removed, likely via biological production, and this was closely linked to decline in N:P ratios. The correlations between DOC, DON, and colored dissolved organic matter suggest that organic matters likely originate from the fish farm wastewater. Quantitatively, the estimated wastewater-derived DOC flux was equivalent to that through submarine groundwater, which is a significant water source on the island. Our results will be able to trace contaminant sources and support assessments of seawater quality for appropriate regulation of fish farm wastewater discharge into coastal zones., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Although recent findings showed that the bioactive lipid metabolites can regulate the ES cell functions, the physiological relevance of interaction between sphingosine-1-phosphate (S1P) and Flk-1 and its related signaling molecules are not yet clear in ES cell proliferation. In the present study, S1P1-5 receptors were expressed in mouse ES cells and S1P increased S1P1-3 receptor expression level. S1P treatment stimulated the cellular proliferation in S1P1/3-dependent manner, located in lipid rafts. In response to S1P, β-arrestin was recruited to S1P1/3 receptor and c-Src was activated. S1P also increased the binding of S1P1/3 receptor with Flk-1. Similar to responses for VEGF, S1P increased Flk-1 phosphorylation, which was blocked by β-arrestin siRNA, and PP2, but not by VEGF-A164 antibody or VEGF siRNA. In addition, S1P induced VEGF expression and VEGFR2 kinase inhibitor (SU1498) blocked the S1P-induced cellular proliferation. However, VEGF-A164 antibody or VEGF siRNA partially blocked S1P-induced cellular proliferation, suggesting that both VEGF-dependent Flk-1 activation and VEGF-independent Flk-1 activation are involved in S1P-induced ES cell proliferation. S1P and VEGF-induced phosphorylation of ERK and JNK were blocked by pretreatment with SU1498. Moreover, inhibition of ERK and JNK blocked S1P-induced cellular proliferation. In conclusion, S1P-elicited transactivation of Flk-1 mediated by S1P1/3-dependent β-arrestin/c-Src pathways stimulated mouse ES cell proliferation., (© 2013.)

Vinylimidazole-grafted poly(3-hydroxyoctanoate) (VI-g-PHO) copolymers were prepared by heating homogeneous solutions of PHO, VI monomer, and benzoylperoxide initiator. The Fourier transform infrared spectroscopy attenuated total reflection and electron spectroscopy for chemical analyses showed that VI was successfully grafted onto the PHO chains. The surfaces and the bulk of VI-g-PHO copolymers became more hydrophilic as the VI grafting density in the copolymer increased. Measurements of the growth of Chinese hamster ovary cells and the adsorption of blood proteins and platelets in vitro showed that biocompatibility was also enhanced by grafting of VI groups. Antimicrobial activity of the VI-g-PHO copolymers was studied against Escherichia coli, Staphylococcus aureus, and Candida albicans. Treatment of each culture suspension with 2.0% (w/v) copolymers for 12h resulted in >90% reduction in viable cell counts against all test microorganisms. These results indicate that the VI-g-PHO copolymers are promising materials for biomedical applications, as they exhibited both biocompatibility and broad spectrum antimicrobial activity., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Glycerol 1,3-diglycerol diacrylate-grafted poly(3-hydroxyoctanoate) (GDD-g-PHO) copolymers were prepared by heating homogeneous solutions of PHO, GDD monomer and benzoylperoxide initiator. Experiments showed that GDD was successfully grafted onto the PHO chains and that the resulting copolymers had enhanced thermal properties and mechanical strengths. The surfaces and the bulk of GDD-g-PHO copolymers became more hydrophilic as the GDD grafting density in the copolymer increased. Measurements of the growth of Chinese hamster ovary cells and the adsorption of blood proteins and platelets in vitro showed that biocompatibility was also enhanced by grafting of GDD groups. These results indicate that the GDD-g-PHO copolymers are promising materials for biocompatible biomedical applications.

Semi-interpenetrating networks (semi-IPNs), where poly(lactide-co-glycolide) (PLGA) molecules were entrapped in the crosslinked matrices of poly(3-hydroxyundecenoate) (PHU), were prepared by irradiating homogeneous solutions of PHU and PLGA in chloroform with UV light. Attenuated total reflectance infrared spectroscopy showed that the PLGA chains were entrapped in PHU networks. The semi-IPNs showed enhanced mechanical strength as the PLGA content increased. The semi-IPNs were incubated at 37 degrees C in a 0.01N NaOH solution, and the extent of hydrolytic degradation was investigated by monitoring changes in various parameters such as water uptake, pH, mass, and morphology. Hydrolysis of semi-IPNs were significantly affected by the presence of PLGA. A semi-IPN prepared from a 9:1 (by weight) mixture of PHU and PLGA lost 25% of its original weight in 12 weeks while a PHU sample containing no PLGA lost only 5% of its weight during the same period under identical conditions. The hydrolysis was most likely accelerated when the pH of the medium was lowered by the hydrolyzed products of PLGA, 2-hydroxyalkanoic acids. These results showed that hydrolysis of PHA could be enhanced by incorporating a second component that lowered the pH of the hydrolysis system.

Poly(ethylene glycol)-grafted poly(3-hydroxyundecenoate) (PEG-g-PHU) networks were prepared by irradiating homogeneous solutions of poly(3-hydroxyundecenoate) (PHU) and the monoacrylate of poly(ethylene glycol) (PEG) with UV light. The resulting polymer networks were characterized by measuring the water contact angle, water uptake, and mechanical properties and by performing attenuated total reflectance infrared spectroscopy and scanning electron microscopy. These measurements showed that the PEG chains were present in polymer networks. Adsorption of blood proteins and platelets on cross-linked PHU (CLPHU) and PEG-g-PHU were examined using poly(L-lactide) (PLLA) surfaces as control. Blood proteins and platelets had significantly lower tendency of adhesion to surfaces composed of CLPHU and PEG-g-PHU networks than to PLLA. Blood compatibility of polymer networks increased as the fraction of grafted PEG increased. The results of this study suggest that PEG-g-PHU networks might be useful for blood-compatible biomedical applications.

Poly(3-hydroxyoctanoate) (PHO) films were treated with plasma of different discharge powers (10-50 W) and then treated with acryl amide solutions in order to prepare films with surfaces that contained different amounts of amide groups. The surfaces were characterized by contact angle measurement, attenuated total reflectance infrared spectroscopy, electron spectroscopy for chemical analysis, and scanning electron microscopy. Results from all these measurements indicated that amide groups were present on the surfaces. The amount of amide groups increased in proportion to the discharge power of the plasma. The interaction of Chinese hamster ovary cells with these grafted surfaces was investigated. The number of cells that adhered to and grew on the surfaces was highest for films grafted at 30 W of plasma discharge power, indicating that the moderate hydrophilicity was optimal for cells to adhere and grow. The present results support the suggestion that acryl amide-grafted PHO could be used as cell-compatible biomedical applications.