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Over the past few decades, various marine biotoxins, including paralytic shellfish poison, diarrheal shellfish poison, neurotoxic shellfish poison, and amnestic shellfish poison, have become international oceanographic concerns. These toxins are closely linked to global warming and the subsequent northward migration of toxic marine organisms, such as microalgae, fish, and benthic invertebrates, from tropical and subtropical regions. In South Korea, the bioaccumulation of marine biotoxins and incidents of seafood poisoning have also emerged as critical issues. Clear evidence indicates that the presence of toxic marine organisms in Korean coastal waters has increased, likely due to recent increases in seawater temperature. Since 2020, supported by the Ministry of Food and Drug Safety, the R&D project ‘Establishment of the Safety Management System for Marine Biotoxins’ has been carried out. This project aims to identify various regulated and unregulated marine biotoxins present in Korean coastal waters and seafood. This comprehensive project encompasses: (1) analytical methods, (2) causative organisms, (3) seafood contamination status, (4) novel and rapid detection method, (5) alternative toxicity testing method, (6) standard materials, and (7) risk assessment. The purpose of this special issue is to share the accumulated knowledge and technological advancements related to marine biotoxins by Korean researchers. The issue includes nine papers covering various types of marine biotoxins, as well as innovative bioassays and rapid detection kits. Additionally, it covers topics such as risk assessment and biotoxin management to ensure the safety of marine products. [ABSTRACT FROM AUTHOR]

The seasonal dynamics of phytoplankton communities in Korean coastal waters (KCWs) are influenced by complex interactions between ocean currents and nearshore human activities. Despite these influences, the understanding of seasonal phytoplankton changes and their environmental relationships in KCWs remains limited. We investigate the influence of the distinct characteristics of the three seas surrounding the KCWs (the Yellow Sea, the South Sea, and the East Sea) on seasonal phytoplankton communities based on field surveys conducted at 23 stations between 2020 and 2021. The East Sea exhibited higher winter temperatures due to the Jeju and Tsushima warm currents, while summer temperatures were lower compared to the other regions, highlighting the role of currents and deeper oceanic waters. The Yellow Sea showed significant freshwater influence with low salinity levels from major rivers, contrasting with the higher salinity in the East Sea. These differences led to a disparity in the productivity of the two regions: the highest value of Chl. a was observed to be 6.05 µg L−1 in the Yellow Sea in summer. Diatoms dominated in nutrient-rich conditions, particularly in the Yellow Sea, where they comprised up to 80–100% of the phytoplankton community in summer, winter, and spring. PCA analysis revealed positive correlations between diatoms and Chl. a, while cryptophytes, which thrive in the absence of diatom proliferation, showed no such correlation, indicating their opportunistic growth in nutrient-limited conditions. This study highlights the significant impact of region-specific hydrographic factors on phytoplankton communities in KCWs, with diatoms dominating in summer and cryptophytes and dinoflagellates showing seasonal and regional variations. Understanding these dynamics is crucial for predicting phytoplankton bloom dynamics and their ecological implications in coastal ecosystems. [ABSTRACT FROM AUTHOR]

Marine plastic debris (MPD) can significantly impact marine ecosystems because it can function as a dispersal vector for organisms, including toxic and alien species. We performed laboratory experiments to assess the possible function of MPD as a dispersal vector for the harmful epiphytic dinoflagellate Fukuyoa koreansis. Specifically, we monitored growth of these cells under 6 conditions: no MPD (control; with or without agitation), with polyethylene (PE) film (sheet-like MPD; with or without agitation), and with polypropylene (PP) rope (cylindrical MPD; with or without agitation). Growth without agitation was not significantly different between experimental groups (p > 0.05, χ2 = 0.228, Kruskal-Wallis test), indicating that the presence of MPDs had no significant effect on growth of F. koreansis under non-agitating conditions. After 15 days, growth without MPD was 25-fold greater without agitation than with agitation (150 ± 42 cells mL-1vs. 6 ± 1 cells mL-1). When grown with both floating MPDs and agitation, 78 ± 1 % of the cells were attached to the MPD, which was 4-times greater than when they were grown without agitation. These results suggest that MPD or another attachment substrate is essential for the growth of F. koreansis in an unstable water mass, and that MPD may provide a habitat or shelter for F. koreansis and thereby function as a dispersal vector for this harmful epiphytic dinoflagellate. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method for user interface (UI) behaviour prediction in commercial applications. The proposed method predicts appropriate UI behaviours for an application by learning repeated UI behaviour sequences from users. To this end, we adopted the long short-term memory algorithm based on the evaluation of a keystroke-level model. Our prediction model takes up to seven consecutive actions as inputs to predict the final UI actions that a user is likely to perform. We verified the effectiveness of the proposed method for both PC applications and mobile game environments. Our experimental results demonstrate that the proposed system can predict user UI behaviours in an application on the client side and provide useful behavioural information for optimising UI layouts. [ABSTRACT FROM AUTHOR]

Typhoons cause significant environmental damage in coastal areas and one of their effects is the suspension of the resting stage cells of diatoms from the surface sediment. We performed microcosm experiments in 10-L containers using natural sediments from three different sites of southern Korean coastal waters (Geoje, Goheung, and Tongyeong) to simulate the effect of suspension of sediment-based diatoms by a typhoon on blooms of the harmful dinoflagellate Cochlodinium polykrikoides. This dinoflagellate grew well under control conditions and exhibited a maximum abundance of 985 cells mL−1 on day 10, but all treatment groups (Geoje, Goheung, and Tongyeong) had decreased abundances by day 4 and fewer than 50 cells mL−1 on day 10. As C. polykrikoides declined, two diatoms (Skeletonema spp. and Chaetoceros spp.) dominated in the three treatment groups. In particular, these diatoms increased to 2.9 × 104 cells mL−1 on day 5 and 2.3 × 104 cells mL−1 on day 7 in the Geoje group. A multivariate redundancy analysis indicated a negative correlation between the abundances of C. polykrikoides and Chaetoceros spp., and this corresponded to the sharpest decrease of C. polykrikoides in the Geoje group. There were also changes in the bacterial community associated with changes in phytoplankton. During the early phase, when C. polykrikoides was dominant, Rhodobacterales prevailed (> 50%) in all treatment groups, and the proportion of these bacteria in the Geoje group decreased earlier than in the other groups. At the end of the experiment, there was a high proportion of Verrucomicrobiales, suggesting that sediment addition led to changes in the bacterial community. Overall, our microcosm experiments suggest that the significant environmental changes following the passage of a typhoon, especially the suspension and proliferation of sediment-based diatoms, directly affects the bacterial community and decreases blooms of C. polykrikoides. [ABSTRACT FROM AUTHOR]

Quantum metrology can achieve enhanced sensitivity for estimating unknown parameters beyond the standard quantum limit. Recently, multiple-phase estimation exploiting quantum resources has attracted intensive interest for its applications in quantum imaging and sensor networks. For multiple-phase estimation, the amount of enhanced sensitivity is dependent on quantum probe states, and multi-mode N00N states are known to be a key resource for this. However, its experimental demonstration has been missing so far since generating such states is highly challenging. Here, we report generation of multi-mode N00N states and experimental demonstration of quantum enhanced multiple-phase estimation using the multi-mode N00N states. In particular, we show that the quantum Cramer-Rao bound can be saturated using our two-photon four-mode N00N state and measurement scheme using a 4 × 4 multi-mode beam splitter. Our multiple-phase estimation strategy provides a faithful platform to investigate multiple parameter estimation scenarios. N00N states are a key resource in quantum metrology, but the use of their multi-mode extension for multiparameter estimation has been elusive so far. Here, the authors use multi-mode N00N states - with N=2 photons in 4 modes - for multiple-phase estimation saturating the quantum Cramer-Rao bound. [ABSTRACT FROM AUTHOR]

We report a new method to optically manipulate a single dielectric particle along closed-loop polygonal trajectories by crossing a suite of all-fiber Bessel-like beams within a single water droplet. Exploiting optical radiation pressure, this method demonstrates the circulation of a single polystyrene bead in both a triangular and a rectangle geometry enabling the trapped particle to undergo multiple circulations successfully. The crossing of the Bessel-like beams creates polygonal corners where the trapped particles successfully make abrupt turns with acute angles, which is a novel capability in microfluidics. This offers an optofluidic paradigm for particle transport overcoming turbulences in conventional microfluidic chips. [ABSTRACT FROM AUTHOR]

Quantum entanglement lies at the heart of quantum mechanics in both fundamental and practical aspects. The entanglement of quantum states has been studied widely both theoretically and experimentally, however, the entanglement of operators has not been studied much experimentally in spite of its importance. Here, we propose a scheme to realize arbitrary entangled operations based on a coherent superposition of local operations with a non-zero probability of failure. Then, we experimentally implement several intriguing two-qubit entangled operations in photonic systems. We also discuss the generalization of our scheme to extend the number of superposed operations and the number of qubits. Due to the simplicity of our scheme, we believe that it can reduce the complexity or required resources of the quantum circuits and provide insights to investigate properties of entangled operations. [ABSTRACT FROM AUTHOR]

We propose a new hollow ring core silica photonic crystal fiber that can support 101 orbital angular momentum (OAM) modes, maintaining a high mode quality without phase distortion, a low confinement loss, and a large effective index difference between the adjacent modes, which could open a new avenue of OAM mode multiplexing applications. The fiber consists of three layers: the circular central air hole, silica ring core, and circumferencing silica-air hole porous inner cladding. Using the full-vectorial finite element method (FEM), the modal characteristics of individual OAM modes in the proposed fiber were thoroughly analyzed by varying the number of air-holes in the circularly symmetric cladding. We found a general selection rule for the number of air-holes in the first layer and the topological charge to cause the phase distortion of OAM modes, for the first time. The phase distribution of the guided OAM modes was thoroughly investigated to select usable modes for mode division multiplexing. Parametric analyses of the proposed PCF are reported to optimize optical properties of the OAM modes. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs are known to be major toxic contaminants in spills of petroleum hydrocarbons (oil). Spilled oil undergoes weathering and over time, PAHs go through a series of compositional changes. PAHs can disrupt endocrine functions, and the type of functions affected and associated potencies vary with the type and alkylation status of PAH. In this study, the potential of five major PAHs of crude oil, i.e., naphthalene, fluorene, dibenzothiophene, phenanthrene, and chrysene, and their alkylated analogues (n = 25), to disrupt endocrine functions was evaluated by use of MVLN-luc and H295R cell lines. In the MVLN-luc bioassay, seven estrogen receptor (ER) agonists were detected among 30 tested PAHs. The greatest ER-mediated potency was observed for 1-methylchrysene (101.4%), followed by phenanthrene and its alkylated analogues (range of %-E2max from 1.6% to 47.3%). In the H295R bioassay, significantly greater syntheses of steroid hormones were observed for 20 PAHs. For major PAHs and their alkylated analogues, disruption of steroidogenesis appeared to be more significant than ER-mediated effects. The number and locations of alkyl-moieties alone could not explain differences in the types or the potencies of toxicities. This observation shows that disruption of endocrine functions by some constituents of oil spills could be underestimated if only parent compounds are considered in assessments of hazard and risk. [ABSTRACT FROM AUTHOR]

The biocontrol effects of Caridina denticulata, an atyid shrimp, on toxic cyanobacterial bloom ( Microcystis aeruginosa) were evaluated in a mesocosm study with stable isotope tracers (C and N) in a eutrophic agricultural reservoir. The accumulated assimilation (at.%) of M. aeruginosa into C. denticulata was increased, causing a significant reduction in the concentration of Chlorophyll- a. The ingestion rate of M. aeruginosa by C. denticulata was influenced by predation pressure exerted by bagrid catfish Pseudobagrus fulvidraco and was dependent on biomass ratio. C. denticulata affected zooplankton density, species composition, and ingestion rate, demonstrating that the number of small-sized cladocerans ( Bosmina coregoni and Bosmina longispina) increased because they grazed M. aeruginosa for a food source. This study suggests that C. denticulata and P. fulvidraco can be feasible material to control a nuisance M. aeruginosa bloom in eutrophic agricultural reservoir. [ABSTRACT FROM AUTHOR]

Effect-directed analysis (EDA) has become useful for identification of toxicant(s) that occur in mixtures in the environment, especially those that are causative agents of specific adverse effects. Here, we summarize and review EDA methodology including preparation of samples, biological analyses, fractionations, and instrumental analyses, highlighting key scientific advancements. A total of 63 documents since 1999 (Scopus search) including 46 research articles, 13 review papers, and 4 project descriptions, have been collected and reviewed in this study. At the early stage (1999-2010), most studies that applied EDA focused on organic extracts of freshwater and coastal contaminated sediments and wastewater. Toxic effects were often measured using cell-based bioassays ( in vitro) and the causative chemicals were identified by use of low resolution gas chromatography with mass selective detector (GCMSD). More recently (2010-present), EDA has been extended to various matrices such as biota, soil, crude oil, and suspended solids and techniques have been improved to include determination of bioavailability in vivo. In particular, methods for non-target screenings of organic chemicals in environmental samples using cutting-edge instrumentation such as time of flight-mass spectrometry (ToF-MS), Fourier transform-ion cyclotron resonance (FT-ICR), and Orbitrap mass spectrometer have been developed. This overview provides descriptions of recent improvements of EDA and suggests future research directions based on current understandings and limitations. [ABSTRACT FROM AUTHOR]

Concern about leakage of carbon dioxide (CO) from deep-sea storage in geological reservoirs is increasing because of its possible adverse effects on marine organisms locally or at nearby coastal areas both in sediment and water column. In the present study, we examined how elevated CO affects various intertidal epibenthic (benthic copepod), intertidal endobenthic (Manila clam and Venus clam), sub-tidal benthic (brittle starfish), and free-living (marine medaka) organisms in areas expected to be impacted by leakage. Acute lethal and sub-lethal effects were detected in the adult stage of all test organisms exposed to varying concentrations of CO, due to the associated decline in pH (8.3 to 5.2) during 96-h exposure. However, intertidal organisms (such as benthic copepods and clams) showed remarkable resistance to elevated CO, with the Venus clam being the most tolerant (LpH = 5.45). Sub-tidal species (such as brittle starfish [LpH = 6.16] and marine medaka [LpH = 5.91]) were more sensitive to elevated CO compared to intertidal species, possibly because they have fewer defensive capabilities. Of note, the exposure duration might regulate the degree of acute sub-lethal effects, as evidenced by the Venus clam, which showed a time-dependent effect to elevated CO. Finally, copper was chosen as a model toxic element to find out the synergistic or antagonistic effects between ocean acidification and metal pollution. Combination of CO and Cu exposure enhances the adverse effects to organisms, generally supporting a synergistic effect scenario. Overall, the significant variation in the degree to which CO adversely affected organisms (viz., working range and strength) was clearly observed, supporting the general concept of species-dependent effects of elevated CO. [ABSTRACT FROM AUTHOR]

An extensive and year-round survey was conducted to assess metal pollution in vast watershed areas of the Selenga River Basin (2007-2009), which provided baseline heavy metal database for the future management. Sources and environmental hazard and risk indices associated with metal pollution were evidenced across the countries of Mongolia and Russia (Buryatia Republic). In general, the concentrations of heavy metals in river water of Mongolia were greater than those of Russia, expect for the upstream of the Dzhida River in Russia. The spatial distribution generally indicated that metal pollution in the Selenga River was mainly associated with the activities in the Mongolian upstream regions. Similar pollution sources of metals between river water and wastewater associated with surrounding activities were found across the industrial and mining areas. Compositional patterns of metals suggested their sources were independent of each other, with hot spots in certain sites. Our measurements indicated that about 63 % of the locations surveyed (48 of 76) exceeded the critical heavy metal pollution index of 100, identifying possible harmful effects on aquatic ecosystems through metal pollution. Zinc was found to be the chemical of priority concern, as more than half of the locations exceeded the corresponding water quality guideline. Other metals including Mn, Fe, Cr, Cu, and As might be problematic in the Selenga River Basin considering the occurrence and their concentrations. Results of our extensive survey during the period of 3 years indicated that urgent action would be necessary in timely manner to improve water quality and mitigate the impact of heavy metals on aquatic environment of the Selenga River Basin. [ABSTRACT FROM AUTHOR]

While the World Health Organization 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) equivalency factors are useful estimates of relative potencies of mixtures when conducting risk assessments, they are not useful when comparing the results of bioassays such as the H4IIE- luc to concentrations of TCDD equivalents calculated from instrumental analyses. Since there are thousands of dioxin-like compounds (DLCs), one use of screening assays is to determine if all of the aryl hydrocarbon receptor (AhR) active DLCs in a mixture have been accounted for in instrumental analyses. For this purpose, bioassay-specific relative potency (ReP) values are needed. RePs of 21 polychlorinated dibenzo- p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls that exhibit effects mediated through the AhR were determined by use of the H4IIE- luc assay. Different values of RePs are derived, depending on the statistical, curve-fitting methods used to derive them from the dose–response relationships. Here, we discuss the various methods for deriving RePs from in vitro data and their assumptions and effects on values of RePs. Full dose–response curves of 2,3,7,8-TCDD and other representative DLCs were used to estimate effective concentrations at multiple points (e.g., EC20-50-80), which were then used to estimate ReP of each DLC to 2,3,7,8-TCDD. [ABSTRACT FROM AUTHOR]

An assessment was made to monitor the short-term impact of heavily polluted sediments that may move out from the brackish man-made Lake Shihwa outside of the sea dike due to operations of a tidal power plant. Here, we exposed the Manila clam Ruditapes philippinarum collected from the western coast of Korea to natural sediment under lab condition for 96 h. Sediments were collected from Lake Shihwa and outside of the sea dike representing polluted and reference conditions, respectively. The results of chemical analysis revealed that the concentrations of nonylphenol and heavy metals in water and sediment from the inner region of Lake Shihwa were significantly higher than those of reference sediments. After 48 and 96 h of exposure, 30 specimens of clams were sampled from each experimental condition, and concentrations of nonylphenol and metals were measured in clams, water, and sediments. Several biomarkers, including concentrations of metallothionein-like proteins, and activities of the antioxidant enzymes glutathione S-transferase and catalase were determined in clams to characterize the effects of polluted sediments to clams. After 96 h of exposure, R. philippinarum assimilated nonylphenol up to 71 times compared to initial concentrations. However, there was no apparent uptake of heavy metals into the clams. Additionally, antioxidant enzymes exhibited higher activities in clams exposed to the polluted sediment. The results of the present study with physiological responses in R. philippinarum suggest that sediment transportation caused by the operation of a tidal power plant in Lake Shihwa will have striking effects on benthic organisms in the adjacent coastal area. [ABSTRACT FROM AUTHOR]

The correct affiliations should read: Center for Quantum Information, Korea Institute of Science and Technology (KIST), Seoul, Korea; Department of Physics, Yonsei University, Seoul, Korea This has now been corrected in both the PDF and HTML versions of the Article. The affiliation of Young-Wook Cho with Department of Physics, Yonsei University, Seoul, Korea was inadvertently omitted. [Extracted from the article]

Fatigue crack propagation (FCP) behavior of friction stir welded (FSWed) 5083-H32 Al alloy was examined with the fatigue crack growing either along the dynamically recrystallized zone (DXZ) at variable Δ K or perpendicular to the DXZ at a constant Δ K value of 10, 13, 15, and 17 MPa√m, respectively. The FCP behavior of FSWed 5083-H32 specimen is substantially influenced by the presence of FSW zone, the trend of which is discussed based on residual stress measurement and fractographic observation. [ABSTRACT FROM AUTHOR]

Homojunction PN and PIN diodes based on 2D transition metal dichalcogenide (TMD) MoTe2 are reported in this work. Up to date, for PN junction diodes, type II‐based heterojunction diodes are mainly seen in report, but homojunction PN diodes using 2D‐layered materials are still rare although they enable seamless integration. Recently, hydrogen (H)‐doped n‐type MoTe2, achieved via atomic layer deposition (ALD) on top of a p‐type MoTe2 surface, was reported. Consequently, a lateral homojunction PN diode was realized by H‐doping. In fact, MoTe2‐based devices with a thickness on the order of nanometers can be applied for short‐wave infrared (SWIR) detection in the range of ≈1300 nm, a wavelength that Si‐based devices cannot properly address. Here, a seamless MoTe2 homojunction PIN diode is demonstrated, achieving the detection of visible to 1300 nm SWIR photons. This thin MoTe2 initially forms a PN junction by selective H‐doping, but a PIN diode is even obtained using two split gates. Compared to the PN diode mode, the PIN mode greatly enhances the photoresponse in the visible to 1300 nm wavelength range because of the increased built‐in electric field. The Franz–Keldysh effect is regarded strongly responsible for the effective absorption of 1300 nm SWIR photons in MoTe2. It is anticipated that this development may support Si photodetectors for integration on Si devices. [ABSTRACT FROM AUTHOR]

In article number 1800118, Emmanuelle Deleporte, Kyunghwan Oh, and co‐workers combine 2D crystallites perovskite ((C5H5C2H4NH3)2PbI4) with a fiber ring laser to confirm its novel nonlinear optic functionality by generating an ultrafast laser in both transform‐limited soliton and dissipative soliton formats at the spectral range covering entire C‐ and L‐bands. It shows the shortest pulse width, the highest repetition rate, the most stable pulse generation, and the highest slope efficiency compared with prior 3D perovskite‐based pulse lasers. [ABSTRACT FROM AUTHOR]

Two‐dimensional hybrid organic–inorganic perovskites have recently attracted attention in various optoelectronic applications. A novel thin film of 2D perovskite (C6H5C2H4NH3)2PbI4 crystallites is synthesized and its nonlinear optical properties are experimentally investigated within the optical gain of an Erbium‐doped fiber. Utilizing its unique nonlinear optical response, efficient mode‐locking of an all‐fiber Erbium laser is demonstrated at the anomalous dispersion regime in both the C‐ and L‐bands stably generating femtosecond pulse trains, where the thin film of 2D perovskite crystallites function as an in‐line saturable absorber. At this anomalous dispersion regime, self‐started femtosecond pulses are generated whose center wavelength are tuned from 1565.9 nm in C‐band and 1604 nm in L‐band by adjusting the optical gain. Furthermore, by managing the chromatic dispersion of the total fiber laser cavity to reach the normal dispersion regime, a stable dissipative soliton is successfully generated in the C‐band with the spectral bandwidth of 15 nm and pulse duration of 3.2 ps. Detailed material properties of the thin film of 2D perovskite crystallites, their characterization, and fiber laser mode‐locking performance is reported. A two‐dimensional crystallites perovskite ((C6H5C2H4NH3)2PbI4) is combined with a fiber laser to confirm its nonlinear optic functionality by generating an ultrafast laser in both transform‐limited soliton and dissipative soliton formats in the entire C‐ and L‐bands. It shows the shortest pulse width, the highest repetition rate, the most stable pulse generation, and the highest slope efficiency compared with 3D perovskite‐based pulse lasers. [ABSTRACT FROM AUTHOR]