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Fluorescent probe for F-actin detection and use thereof
No full textKIOST-Fluor 화학 골격의 N-4 위치와 C-7 위치에 천연물 phalloidin-linker를 도입하여 F-actin을 효과적
으로 형광 염색할 수 있는 형광 화학 프로브를 합성하는 방법과 고해상도 형광 이미지를 얻는 방
Characteristics of Water Quality and Sediment Distributions on the Northeastern Coast of Jeju Island
No full textSince the 1980s, the number of land-based fish farms on Jeju Island has increased rapidly. With increasing land-based fish farms, a large amount of nutrients from fish farm wastewater is discharged off the coast of Jeju. To understand the characteristics of coastal seawater and the ecological environment on the coast of Jeju, the effect of land-based fish farm effluent on coastal seawater should be evaluated. Temperature, salinity, nutrients, and chlorophyll-a concentration were investigated on the northeastern coast of Jeju during June and July 2023. Nitrate, phosphate, and silicate concentrations in the surface waters were significantly higher in coastal stations than in the outer stations. Unlike the surface waters, nutrient concentrations in the bottom waters are distinctly higher in land-based fish farm effluent stations than in the outer stations. Total organic carbon content in surface sediment was significantly higher in land-based fish farm effluent stations than in the outer stations. This study may provide valuable information for evaluating the impact of land-based fish farm effluent on coastal ecosystems on Jeju Island.22Ykc
Roseovarius conchicola sp. nov. and Aliiroseovarius conchicola sp. nov., isolated from the marine conch Reishia bronni
No full textThe intertidal zone is an area located between the marine environment and the terrestrial environment and is exposed to various stresses. To investigate the mutualistic relationship between hosts and symbiotic micro-organisms inhabiting the intertidal zone, strains 2305UL8-3T and 2305UL8-7T were isolated from Reishia bronni, a species living in the intertidal zone of Ulleungdo Island, South Korea. Both strains are Gram-stain-negative, catalase- and oxidase-positive and facultatively anaerobic. Strains 2305UL8-3T and 2305UL8-7T grow optimally at 30.0 °C and 28.0–30.0 °C, respectively, under conditions of pH 8.0 and 3.0 % (w/v) NaCl. They have Q-10 as the primary quinone, and their common main fatty acids are C16:0 and summed feature 8 (C18:1 ω7c and/or C18:1 ω6c). Additionally, their primary polar lipids include phosphatidylcholine and phosphatidylglycerol. The two novel strains have an arsenic reduction pathway that reduces the oxidation state of arsenic and are expected to influence environmental regulation processes through the catabolic sulphate reduction system. Based on these characteristics, they exhibit resistance potential to environmental stresses, specifically arsenic exposure in the intertidal zone, where arsenic contamination is often associated with pollution and tidal fluctuations. Analysing the 16S rRNA gene sequence similarity, strain 2305UL8-3T shared 96.60 % similarity with Roseovarius faecimaris MME-070T, while strain 2305UL8-7T showed 98.13 % similarity with Aliiroseovarius sediminilitoris M-M10T. Polyphasic analysis revealed that strains 2305UL8-3T and 2305UL8-7T should be identified as novel species within the genera Roseovarius and Aliiroseovarius, respectively. Therefore, Roseovarius conchicola sp. nov. with the type strain 2305UL8-3T (=KCTC 8475T=MCCC 1K09523T=JCM 37202T) and Aliiroseovarius conchicola sp. nov. with the type strain 2305UL8-7T (=KCTC 8476T=MCCC 1K09524T=JCM 37203T) are proposed.11Nsciescopu
Optimal Route Design and Operational Efficiency Analysis of Wind-Assisted Propulsion Ships Using Graph Networks
No full textThis study focuses on exploring the optimal routes for Wind-Assisted Propulsion Ship (WAPS), targeting enhanced fuel efficiency and greenhouse gas reduction in maritime operations, using a 17K DWT bulk carrier equipped with a 2.4MW dual-fuel engine and four medium-sized rotor-sails as auxiliary propulsion devices. The research assesses the efficiency of these routes by comparing the fuel consumption on the shortest distance and the optimal route utilizing wind-assisted propulsion system crossing the North Atlantic Ocean. A numerical analysis of rotor-sails was conducted and node-based graph network was employed to construct a navigational map for searching optimal route utilizing wind and ship data. Ships using only their main propulsion system were compared to those equipped with rotor-sails. When following the shortest route, ship with rotor-sails achieved a 7.6% fuel saving. Additionally, by optimizing the route to take advantage of wind conditions favorable for rotor-sails, an extra 10.9% fuel saving was observed. This research analyzes the practical applicability of wind-assisted propulsion technology and aims to contribute to compliance with eco-friendly regulations in the maritime industry.22Nkc
AUTOMATED DETACHABLE REMOVABLE APPARATURS FOR SUCTION PILES USING CLAMP
No full text본 제안기술은 석션앵커 시스템이 석션앵커에 안착되면 다수개의 클램프가 들고리를 양쪽에서 가압하여 결
합되거나 분리되도록 구성되거나, 밸브체의 플랜지와 연결체의 플랜지를 동시에 결합하도록 구성됨으로써
보다 견고한 결합상태를 유지할 수 있는 특징이 있다
Seasonal Effects of Nakdong River Freshwater Inflow and Coastal Environmental Changes on Phytoplankton Community Structure, Including Harmful Species, in Eastern Jinhae Bay, Korea
No full textRainfall-induced freshwater influx is a major nutrient source in estuarine and coastal waters, often driving changes in phytoplankton community structure and blooms. In Jinhae Bay of Korea, a critical area for shellfish aquaculture, the interaction between the Nakdong River discharge and the Tsushima Warm Current creates a frontal zone conducive to phytoplankton proliferation. This study investigated the seasonal variation in phytoplankton communities, including harmful and toxin-producing species, in relation to environmental factors from February 2022 to November 2023 in Jinhae Bay. Except for the summer increase in certain dinoflagellates, diatoms, including Chaetoceros spp., Pseudo-nitzschia spp., and Skeletonema spp., dominated the phytoplankton community across seasons. In addition, nutrient influx from the Nakdong River, particularly nitrate + nitrite and silicate (p < 0.001), was a key driver of phytoplankton community structure. Spatially, phytoplankton communities differed between the inner (St. 1 and 4) and outer (St. 2 and 3) areas in the bay, likely due to the influences of seasonal river discharge, the Tsushima Warm Current, and tidal currents. Among harmful algal blooms causative species, dinoflagellate Margalefidnium polykrikoides was correlated with water temperature, exhibiting higher densities in summer. In contrast, Akashiwo sanguinea was mainly observed in winter. In addition, we found that toxin-producing dinoflagellates, such as Alexandrium catenella, Dinophysis acuminata, and Gonyaulax spinifera, were most prevalent in spring and summer, and their appearance was linked to complex interactions among freshwater influx, water temperature, and current dynamics. Our findings underscore the critical role of bay-specific oceanographic conditions, shaped by tidal and current patterns, in conjunction with riverine nutrient inputs, in driving seasonal phytoplankton blooms. This study provides valuable baseline data for understanding harmful/toxic microalgal dynamics in Jinhae Bay and offers key insights for effective coastal ecosystem management and conservation along the Korean Peninsula.11Nsciescopu
Derivation of the Controllable Region for Attitude Control of Towfish and Verification Through Water Tank Test
No full textWe investigated the attitude control of a towfish to enhance the image quality of its sound navigation ranging system. The target towfish is equipped with two elevators on the horizontal tail wing, and attitude control is performed using these actuators. In particular, when a high-resolution sonar system is mounted on the towfish, any irregular movement can cause defocusing; thus, attitude control of the towfish is essential. Because the towfish has no thrust of its own and moves by being connected to a mother vessel via a cable, its attitude must be controlled by comprehensively analyzing its towing force and equation of motion. Herein, we propose a method for calculating the region where the attitude of the towfish can be controlled based on changes in the center of gravity, towing speed, and towing point. We conducted a water tank test to verify this method and confirmed that the attitude of the towfish could be controlled in controllable areas but not in uncontrollable regions.11Nsciescopu
Evidence of methanogenic activity associated with past fish farming in Lake Soyang, South Korea
No full textIn this study, a 54-cm-long sediment core was collected from an area with a history of fish farming to investigate a potential link between methane production and past aquaculture activities in Lake Soyang, a large artificial lake (ca. 2-110 m water depth, 16.08 km(2) in area). Along with bulk elements (carbon and nitrogen), we analyzed specific lipid biomarkers, including n-alkanes, sterols, glycerol dialkyl diethers (DGDs), and glycerol dialkyl glycerol tetraethers (GDGTs). Additionally, we measured the compound-specific carbon isotopic composition (delta C-13) of specific lipids, excluding GDGTs. Evidence of prior aquaculture activities was indicated by high total organic carbon content (similar to 30 wt%) and elevated concentrations of coprostanol and stigmasterol, reflecting substantial deposition of mixed organic matter (OM) from aquaculture practices, such as fish feed and feces. The delta C-13 values of sterols (- 28.4 +/- 1.4 parts per thousand) were relatively enriched compared to those of isoprenoid DGDs, such as archaeol and OH-archaeol (- 40.0 +/- 3.2 parts per thousand). This suggests that increased acetoclastic methanogenic activities may be closely linked to the assimilation of by-products derived from aquaculture-related OM as potential carbon sources. Our findings highlight the potential importance of methane production within aquaculture systems and the environmental factors influencing this process. These results could inform the development of systematic management strategies to mitigate methane emissions from aquaculture systems.11Nsciescopu
Microplastic emissions from fishing ropes: Quantification, characteristics, and implications for marine pollution
No full textThis study quantifies and characterizes microplastics generated through the mechanical abrasion of fishing ropes, a significant yet often overlooked source of marine microplastic pollution. A custom-designed hauler system was used to evaluate the quantity, size distribution, and morphology of microplastics released from polypropylene-based co-polymer ropes under varying hauling weights (5–50 kg) and operational frequencies (1–20 cycles). The results indicated that 92 ± 3% of the released microplastics were non-fiber fragments, closely resembling those observed in Korean coastal waters. A linear regression analysis revealed that each 1 kg increase in hauling weight produced an additional 1.383 microplastic particles per meter. Global estimates suggest that abrasion from new ropes releases approximately 768 trillion microplastic particles (2.8 kilotons) annually. These findings emphasize the substantial contribution of fishing gear abrasion to marine microplastic pollution. Future research is needed to explore polymer-specific fragmentation, environmental weathering, and the fate of particles to refine emission estimates.11Nsciescopu
Residual Overturning Circulation and Associated Water-Mass Transformation in the East/Japan Sea
No full textThe East/Japan Sea (EJS), a marginal sea in the northwest Pacific, has marked isopycnal slopes, especially during winter, implying a store of potential energy available for baroclinic instability and hence, perhaps, a significant role for eddy processes in shaping the residual (mean plus eddy) overturning circulation. Here, for the first time, we compute the residual overturning circulation in the EJS in a high-resolution simulation and relate it to water-mass transformation processes due to air-sea fluxes and interior mixing. A sizable eddy-driven circulation is indeed found in the vicinity of tilted isopycnals. Wintertime surface buoyancy loss facilitates a volume flux toward higher-density classes, with latent heat loss being the main contributor and sensible heat loss also playing a role. The densification of northward subsurface flow is associated with diapycnal mixing. The water-mass formation rate, derived from the transformation rate, identifies upwelling and downwelling to the south and north of the subpolar front near 39.58N, respectively, consistent with the broad pattern of residual overturning circulation.11Nsciescopu