The Middle and Late Holocene climate change in Bohai Bay revealed by diatom proxy

A total of 98 samples from two boreholes in shallow sea area and two oyster reefs in adjacent coastal plain in the northwestern coast of Bohai Bay were collected for diatom analyses and species identification.The ratio of the marine species Thalassionema nitzschioides to the intertidal-coastal species complex Cyclotella striata/stylorum serves as a novel proxy for assessing the strength of marine influence.Chronological data,corrected for the local residence time effect,facilitated the construction of a diatom proxy-based marine influence curve for the study area.This curve delineates the dynamics of marine influence and their correlations with paleo-climate fluctuations and the East Asian monsoon variability,as well as their role in chenier formation.Results include:(1)eight periods of intensified marine influence have been documented since 7000 a BP in the study area.The peak of each period,as determined by the diatom proxy,corresponds closely to the warm climatic phases and stronger East Asian summer monsoons,suggesting that the peaks marine influence indicate typically the periods of climatic warmth and monsoon activity intensification in the region;(2)a strong correlation exists between the development of cheniers and marine influence,and chenier formation began with the increasing marine influence and terminated at the end of warm periods as marine influence weakens.The climatic changes in the coastal area,as indicated by the diatom proxy,hold significant potential for future related research endeavors.

Direct electrospinning method for the construction of Z-scheme TiO_2/g-C_3N_4/RGO ternary heterojunction photocatalysts with remarkably ameliorated photocatalytic performance

A series of Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigated comprehensively in terms of crystal structure, morphology, composition, specific surface area, photoelectrochemical properties, photodegradation performance, etc. Compared with binary TiO2/g-C3N4 and single-component photocatalysts, ternary heterojunction photocatalysts show the best photodegradation performance for RhB under stimulated sunlight. This can be attributed to the enlarged specific surface area (111.41 m2/g), the formation of Z-scheme heterojunction, and the high separation migration efficiency of photoexcited charge carriers. A potential Z-scheme mechanism for ternary heterojunction photocatalysts is proposed to elucidate the remarkably ameliorated photocatalytic performance based on active species trapping experiments, PL detection test of hydroxyl radicals, and photoelectrochemical properties.

以数字化转型引领教育场景变革——江苏智慧教育生态建构的实践及愿景

作为全国最早全面布局智慧教育建设的省份,江苏通过强化顶层设计、深化融合创新、优化保障机制,高起点推进智慧校园建设,高质量打造智慧校园品牌,高水平支撑智慧校园发展,大力推进江苏智慧教育生态建构实践。为加快推进数字化转型和智能化提升,江苏积极谋划推进教育新基建布局等八项重点工程,健全完善教育新基础设施等五大支撑体系,努力拓展智慧课堂等十大智慧教育应用场景,不断夯实智慧教育数字底座,持续创新智慧教育应用,探索推进教育场景变革,努力建构智慧教育新生态,积极赋能高质量教育体系、高标准教育强省建设。

Numerical simulations and comparative analysis for two types of storm surges in the Bohai Sea using a coupled atmosphere-ocean model

The Bohai Sea is extremely susceptible to storm surges induced by extratropical storms and tropical cyclones in nearly every season. In order to relieve the impacts of storm surge disasters on structures and human lives in coastal regions, it is very important to understand the occurring of the severe storm surges. The previous research is mostly restricted to a single type of storm surge caused by extratropical storm or tropical cyclone. In present paper, a coupled atmosphere-ocean model is developed to study the storm surges induced by two types of extreme weather conditions. Two special cases happened in the Bohai Sea are simulated successively. The wind intensity and minimum sea-level pressure derived from the Weather Research and Forecasting (WRF) model agree well with the observed data. The computed time series of water level obtained from the Regional Ocean Modeling System (ROMS) also are in good agreement with the tide gauge observations. The structures of the wind fields and average currents for two types of storm surges are analyzed and compared. The results of coupled model are compared with those from the uncoupled model. The case studies indicate that the wind field and structure of the ocean surface current have great differences between extratropical storm surge and typhoon storm surge. The magnitude of storm surge in the Bohai Sea is shown mainly determined by the ocean surface driving force, but greatly affected by the coastal geometry and bathymetry.

Holocene sea level trend on the west coast of Bohai Bay,China: reanalysis and standardization

Using 110 newly revised Holocene sea level indicators categorized into three types,sediments(67),shelly cheniers(27)and oyster reefs(16),this paper firstly provides a Holocene relative sea level curve,based on multiple approaches of litho-and biostratigraphies and sedimentary faces analysis,for the west coast of Bohai Bay,China.Following considerations,including indicative meaning,the paleo tidal pattern and range and conversion from mean tidal level to mean sea level,an apparent relative mean sea level(RMSL)curve was further reconstructed.After systematical calibration using CALIB,those of the 48 reworked samples were further corrected for the residence-time effect.Similarly,the younger ages for another 35 samples were chosen at the subsample level.These result in a younger-oriented shift for about 0.5 ka.Three local spatial factors,including neotectonic subsidence(average rate about 0.1 mm/a),self-compaction of unconsolidated sediments(between a few decimeters to about 6 m)and subsidence due to groundwater withdrawal(between a few centimeters to about 2.5 m),were quantitatively corrected.Finally,the amended RMSL curve after eliminating all these local temporo-spatial factors is very likely to show non-existence of mid-Holocene highstand and imply potential influences of both ice-volume equivalent sea level and regional glacial isostatic adjustment.Although it is still unable to divide both global and regional factors,the slowdown of sea level rise,in 7.5–6.8 ka with a maximum height less than+1 m,may constrain the model effort in the near future.

Dexmedetomidine alleviates oxygen and glucose deprivation-induced apoptosis in mesenchymal stem cell via downregulation of MKP-1

Bone marrow mesenchymal stem cell(MSC)-based therapy is a novel candidate for heart repair.But ischemiareperfusion injury leads to low viability of MSC.Dexmedetomidine(Dex)has been found to protect neurons against ischemia-reperfusion injury.It remains unknown if Dex could increase the viability of MSCs under ischemia.The present study is to observe the potential protective effect of Dex on MSCs under ischemia and its underlying mechanisms.Specific mRNAs related to myocardial ischemia in the GEO database were selected from the mRNA profiles assessed in a previous study using microarray.The most dysregulated mRNAs of the specific ones from the above study were subject to bioinformatics analysis at our laboratory.These dysregulated mRNAs possibly regulated apoptosis of cardiomyocytes and were validated in vitro for their protective effect on MSCs under ischemia.MSCs were pre-treated with Dex at 10μM concentration for 24 h under oxygen-glucose deprivation(OGD).Flow cytometry and TUNEL assay were carried out to detect apoptosis in Dex-pretreated MSCs under OGD.The relative expressions of mitogen-activated protein kinase phosphatase 1(MKP-1)and related genes were detected by quantitative polymerase chain reaction and western blotting.Microarray data analysis revealed that Dex regulates MAPK phosphatase activity.Dex significantly reduced in vitro apoptosis of MSCs under OGD,which suppressed the synthesis level of Beclin1 and light chain 3 proteins.Dex down-regulated MKP-1 expression and attenuated an OGDinduced change in the mitogen activated protein kinase 3(MAPK3)signaling pathway.Dex increases the viability of MSC and improves its tolerance to OGD in association with the MKP-1 signaling pathway,thus suggesting the potential of Dex as a novel strategy for promoting MSCs efficacy under ischemia.

Electrochemical removal of ammonium nitrogen in high efficiency and N_(2) selectivity using non-noble single-atomic iron catalyst

Ammonia nitrogen (NH_(4)^(+)-N) is a ubiquitous environmental pollutant,especially in offshore aquaculture systems.Electrochemical oxidation is very promising to remove NH_(4)^(+)-N,but suffers from the use of precious metals anodes.In this work,a robust and cheap electrocatalyst,iron single-atoms distributed in nitrogen-doped carbon (Fe-SAs/N-C),was developed for electrochemical removal of NH_(4)^(+)-N from in wastewater containing chloride.The FeSAs/N-C catalyst exhibited superior activity than that of iron nanoparticles loaded carbon(Fe-NPs/N-C),unmodified carbon and conventional Ti/IrO_(2)-TiO_(2)-RuO_(2)electrodes.And high removal efficiency (>99%) could be achieved as well as high N_(2)selectivity (99.5%) at low current density.Further experiments and density functional theory (DFT) calculations demonstrated the indispensable role of single-atom iron in the promoted generation of chloride derived species for efficient removal of NH_(4)^(+)-N.This study provides promising inexpensive catalysts for NH_(4)^(+)-N removal in aquaculture wastewater.