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Antiviral potential of fucoxanthin, an edible carotenoid purified from Sargassum Siliquastrum, against the zika virus
No full text1
Development of Depressurized Seawater Circulation System for Underwater Radiation Onsite Monitoring
No full text우리나라를 포함한 주변국(중국, 일본, 러시아)은 원자력발전소의 보유 수 및 국가 전력 생산에 원자력발전 의존도가 매우 높은 지역으로 후쿠시마 방사능 오염수 방류와 더불어 안전한 원자력발전의 운영을 위하여 인공방사능 핵종의 해양환경 유입에 따른 해양오염과 수산물에 대한 영향에 대한 지속적인 모니터링이 필요하다. 기존의 해양 방사능 분석은 60kg 이상의 해수를 채수 후 실험실로 이동하여3일 이상의 농축 및 분석을 수행하는 방식으로, 시료의 공간·시간적 대표성이 제한되고 현장 대응성이 떨어지는 문제가 있다. 이에 본 연구에서는 최대 300m 수심까지 외부 압력을 견디며, 내부는 대기압을 유지할 수 있는 감압 시스템을 통하여 수중 방사선 변화량을 현장에서 신속하게 측정할 수 있는 수중 방사선 검출시스템의 핵심기술인 해수 감압 순환 시스템을 개발하고자 한다. 해수 감압 순환 시스템은 외부 해수를 유입한 후 일정한 압력에서 순환시켜 내부에 설치된 방사선 검출 센서를 통해 실시간으로 방사선 신호를 측정하게 한다. 본 시스템은 물리적으로는 수심 변화에 따라 내압을 보정 하여 안정적으로 방사선 센서가 동작하도록 설계되었으며, 수면부터 특정 수심까지 해수 내 방사성 핵종의 현장 평가를 가능하게 한다. 물론, 대용량 해수 시료 채취를 통한 실험실 정밀 분석을 통해 해양환경 방사능 분석 방식과 비교하여 상대적으로 높은 최소 검출 가능 농도를 가지고 있으나, 이동플랫폼과 결합한다면 정점 기반의 해양환경 방사능 감시망의 효율적인 확대는 물론, 원자력발전 관련사고 발생 시 신속 대응 기술로 활용이 가능하다. 향후 시제품 성능 검증과 함께 무인 이동체 플랫폼에 적용성 검토 및 다양한 수심 및 환경 조건에서 수중 실험을 통해 기술의 현장 적용성을 높이고자 한다.2
Assessing coastal topographic changes through integrated long-term monitoring system: a case study of hujeong beach
No full textThe sandy beaches along the east coast of the Republic of Korea exhibit dynamically evolving crescent-shaped sandbars and shorelines that continuously reshape in response to external forces. In addition, many of these beaches coexist with infrastructure such as ports and power plants, making the study of coastal morphological changes essential for effective coastal management, including environmental protection, tourism, and infrastructure maintenance. However, long-term studies on nearshore hydrodynamics and coastal topographic changes remain insufficient. This study address this gap by implementing an integrated long-term monitoring system focused on Hujeong Beach, a representative sandy beach along the east coast of South Korea. Hujeong Beach, located in the middle of the east coast, has a sandy about 3 km-long northeast-facing sandy shoreline (Fig. 1). At its northwestern end, a breakwater (P1) was constructed for a power plant, and a submerged breakwater (P2) was installed to protect a pier (Do et., al, 2020). To obtain high-resolution nearshore seabed bathymetry measurements, a 2,000 m × 500 m coastal area was divided into three zones based on water depth, with annual surveys conducted from 2016 to 2023. The nearshore zone (up to 15 m depth) was surveyed using a single-beam echosounder at 20 m intervals, while deeper waters (10–40 m depth) were mapped with a multi-beam echosounder. The backshore morphology was captured using RTK drone. The collected topographic data from these three zones were integrated and spatially interpolated to estimate total sand volume changes. Additionally, satellite imagery and video tower observations were utilized to complement shoreline analysis (Do et., al, 2021). The long-term monitoring results provide valuable insights into shoreline evolution, aiding in coastal change prediction and management. The study highlights the relationship between topographic variations and external forcing mechanisms, identifies erosion-prone areas, and contributes to the development of sustainable coastal management strategies.1
Heterologous arabinose-inducible gene expression in hyperthermophilic archaeon Thermococcus onnurineus NA1
No full textIn this study, we established an inducible gene expression system in Thermococcus onnurineus NA1, a strain known for its efficient hydrogen (H2) production from formate, This hyperthermophilic archaeon is incapable of utilizing pentose sugars, making it advantageous for establishing a leak-free inducible system. We accomplished this by employing a heterologous arabinose-inducible expression module derived from Sulfolobus acidocaldarius. This module consists of the xylF, xylG, and xylH gene cluster, responsible for pentose transport, along with the transcriptional regulator xylR. These genes were integrated into genome using selected ribosome binding sites, a promoter, and a terminator. We determined the optimal concentration of arabinose and the induction time required to induce gene expression. Western blot analysis confirmed the system is functioning effectively. This study demonstrates a controllable protein expression platform in T. onnurineus NA1 using a heterologous arabinose-inducible system. It underscores the potential of this system as a versatile biofactory platform, which will be further validated through simultaneous protein and H₂ production2
From simulation to projection: The North Pacific SST variability in CMIP6
No full textGlobal sea surface temperatures (SST) have been rising rapidly in response to global warming,
with certain regions of the North Pacific warming at rates two to three times higher than the
global average. However, research on SST variability, beyond the magnitude of this warming,
remains limited. This study analyzes CMIP6 models’ data to investigate the simulation of past
characteristics and future changes in seasonal and interannual SST variability. The analysis was
conducted using 31 CMIP6 models and included the historical, SSP2-4.5, and SSP5-8.5
scenarios.
In the northwestern Pacific, the amplitude of seasonal variability is pronounced in the mid
latitudes,
particularly in the Kuroshio Extension region. Climate models tend to underestimate
variability in the mid-latitudes and overestimate it in the low latitudes of the Pacific. Projections
indicate that the amplitude of seasonal variability in the North Pacific will increase in the future,
with a greater increase under SSP5-8.5 scenarios. Interannual variability tends to decrease under
2-4.5 scenarios but increases under 5-8.5 scenarios.
These results suggest that future SST variability distributions will differ depending on carbon
dioxide emissions and region, with the Kuroshio Extension showing particularly large
differences, both seasonally and among models, compared to other regions.1
Deriving hourly diagnostic surface velocity fields considering inertia and an application in the Yellow Sea
No full textSurface currents play an important role in the transport of floating materials in the Yellow Sea, a region strongly influenced by tidal forcing and seasonal wind variability driven by the East Asian monsoon. While diagnostic models have been widely used to estimate surface currents, due to their steady-state assumption, high frequency variations such as tides and inertial oscillations cannot be resolved. To address this limitation, a time-dependent diagnostic model incorporating inertial terms into the governing equations is proposed. The performance of the proposed method is evaluated using buoy and drifter observations from 2015 to 2023. The time-dependent model in this study captures not only low frequency components (geostrophic and Ekman currents) but also high frequency variability (inertial oscillations and tides). Compared to the traditional model assuming steady-state, it shows significant improvement, achieving a correlation of 0.76 and Root-Mean-Square Error of 0.18 m s−1 (compared to −0.08 and 0.43 m s−1 for the steady model, that caused by wrong governing equation ignoring inertia to describe tides) because of successful consideration of high frequency variability. The decay rate of inertial oscillations is analytically derived, providing insight into the time scale for past signals in surface currents to dissipate. We expect that this study offers a practical framework for surface current estimation considering both high and low frequency signals and can be applied for quick assessments of material transport in other coastal oceans.11Ysciescopu