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.

Pacific oyster(Crassostrea gigas)shell growth duration in a year in Bohai Bay and implication for its carbon sink potential

Oyster is a bivalve mollusk widely distributed in estuarine and shallow sea environments.Its growth and burial process is a carbon sequestration and storage process.Oyster shell may stop growing due to suffer from freeze shock during the winter season within a temperate climate,therefore,in order to study the carbon sequestration capacity of oysters we need to know the water temperature at which the shell suffer from winter freeze shock.This study examinesδ^(18)O profiles across consecutive micro-growth layers found in three modern Pacific oyster shells from the northwest coast of Bohai Bay.A total of 165 oxygen isotope values from sequential samples of their left shells showed periodically varying values,and the variation fluctuation of oxygen isotope values was 4.97‰on average.According to the variation range of the oxygen isotope value of the shell,combined with the sea surface temperature and the sea surface salinity data of the water in which the oysters grew,the water temperature that suffer from winter freeze shock and stops or retards the growth of Pacific oysters in Bohai Bay is about 8.3℃,and the corresponding period is from December to March of the following year.The calcification time of oysters within one year is nearly a month longer than previously thought,therefore,its carbon sink potential is also improved.

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.

Mobile bed thickness in skewed asymmetric oscillatory sheet flows

A new instantaneous mobile bed thickness model is presented for sediment transport in skewed asymmetric oscillatory sheet flows. The proposed model includes a basic bed load part and a suspended load part related to the Shields parameter, and takes into account the effects of mass conservation, phase-lag, and asymmetric boundary layer development, which are important in skewed asymmetric flows but usually absent in classical models. The proposed model is validated by erosion depth and sheet flow layer thickness data in both steady and unsteady flows, and applied to a new instantaneous sediment transport rate formula. With higher accuracy than classical empirical models in steady flows, the new formula can also be used for instantaneous sediment transport rate prediction in skewed asymmetric oscillatory sheet flows.

Episodic crustal growth in the Tanzania Craton:evidence from Nd isotope compositions

The analysis of available Nd isotope data from the Tanzania Craton places important constraints on the crest-mantle separation ages,and events marking juvenile crustal addition and crustal recycling.Nd model ages date the oldest crust extraction to 3.16 Ga in the Tanzania Craton,although a rock record of such antiquity is yet to be found there.The most significant period of juvenile crustal addition as well as crustal recycling is 2.7-2.6 Ga.The Nd isotopes of marie samples show that chemical heterogeneity existed in the mantle beneath the Tanzania Craton,with some samples originating from significantly depleted mantle, and most samples originating from the mixture of primitive mantle and depleted mantle.The Nd isotope section reveals significant differences in Nd isotopes between the north eraton and central craton;compared to the north craton,the central craton yields a Nd model age that is approximately 100 Ma older, and its εNd(t)values are more negative,indicating that the two parts of the craton have different mantle source regions.Different types of granitoids are distributed in the Tanzania Craton,such as high-K and low-Al granite,ealc-alkaline granite,peraluminous granite and transitional types of tonalite-trondhjemite- granodiorites (TTGs).Most of the granitoids formed later than the marie rocks in syn-collision and postcollision events.

Radiocarbon ages of different fractions of peat on coastal lowland of Bohai Bay: marine influence?

Peat in boreholes is the most important ^(14)C dating material used for constructing age framework. 20 bulk peat samples were collected from five boreholes, the ^(14)C ages of two fractions(organic sediment fraction and peat fraction) of the bulk peat samples were investigated by AMS-dating and which fraction is better to help construct an age framework for the boreholes were compared and discussed. The results indicated that the peat fraction give a good dating results sequence in the boreholes, compared with the corresponding organic sediment fraction. And the dating results of organic sediment fraction show 161-6 702 years older than corresponding peat fraction, which was caused by marine influence. Then, we suggest an experience formula as y =0.99 x-466.5 by the correlation analysis for correcting the marine influenced organic sediment ages within the conventional ages between 4 000 to 9 000 yrs BP, and more study should be carried out for the AMS ^(14)C dating of the bulk organic sediments.

Quantitative relationship between surface sedimentary diatoms and water depth in North-Central Bohai Bay,China

To study the quantitative relationship between surface sedimentary diatoms and water depth,67 surface samples were collected for diatom analysis on eight profiles with water depth variation from the muddy intertidal zone to the shallow sea area in North-Central Bohai Bay,China.The results showed that the distribution of diatoms changed significantly in response to the change in water depth.Furthermore,the quantitative relationship between the distribution of dominant diatom species,their assemblages,and the water depth was established.The water depth optima for seven dominant species such as Cyclotella striata/stylorum,Paralia sulcata,and Coscinodiscus perforatus and the water depth indication range of seven diatom assemblages were obtained in the study area above the water depth(elevation)of-10 m.The quantitative relationship between surface sedimentary diatoms and water depth provides a proxy index for diatom-paleo-water depth reconstruction in the strata in Bohai Bay,China.

Efficacy of high-flow nasal cannula on acute exacerbation of chronic obstructive pulmonary disease: A meta-analysis

Objective:To systematically evaluate the efficacy and feasibility of high-flow nasal cannula(HFNC)on patients with acute exacerbation of chronic obstructive pulmonary disease(AECOPD).Methods:Systematic searches on PubMed,Web of Science,the Cochrane Library,Embase,CBM(Chinese Biomedicine Database),CNKI(China National Knowledge Infrastructure),Wanfang Database and VIP were performed for randomized controlled trials(RCTs)which explored the effects of HFNC on patients with AECOPD.The retrieval time was from the establishment of each database to July 2019.RevMan5.3 software was used for statistical analysis.Results:A total of 12 articles were included,involving 812 patients.The results showed that:(1)Compared with conventional oxygen therapy,HFNC could improve patients'arterial partial oxygen pressure(PaO2)(MD=12.70,95%CI(7.00,18.40),Z=4.37,P<0.0001),reduce partial arterial blood carbon dioxide(PaCO2)(MD=-10.99,95%CI(-14.42,-7.55),Z=6.26,P<0.00001)and reduce endotracheal intubation rate(OR=0.19,95%CI(0.04,0.93),Z=2.05,P=0.04),shorten the hospitalization time(SMD=-0.74,95%CI(-1.11,-0.37),Z=3.95,P<0.0001).(2)Compared with non-invasive positive pressure ventilation,it has fewer adverse reactions(OR=0.18,95%CI(0.09,0.35),Z=5.08,P<0.00001)and shorter hospital stay(SMD=-0.57,95%CI(-0.90,-0.23),Z=3.33,P=0.0009).Conclusion:HFNC can improve the patients’hypoxia symptoms and CO2 retention,reduce the rate of tracheal intubation,and alleviate adverse reactions.However,Limited by the quality and region of the included studies,more high-quality are needed to test it.

The Progress of Case Teaching Method for Postgraduate Nursing Education

The development of postgraduate nursing education is a major tendency of the nursing industry in the future.Cultivation method is closely related to the progress of nursing postgraduate talents.In order to provide proper education support,this article reviews the progress of the development of case teaching method in postgraduate nursing education,the concept of case teaching,the development status around the world.Moreover,this review specially reviewed the application process of case teaching method.

Effective Nikuradse Roughness on the Mobile Plan Bed

Nikuradse roughness(ks) is very important in the sediment transport prediction because it is related to the evaluations of the velocity distribution, shear stress and erosion depth. Dimensionless Nikuradse roughness(ks/D,where D is the sediment diameter) is usually given 1–2.5 on the immobile plan bed or at low shear stress. But it behaves differently on the mobile plan bed at high shear stress with much sediment picked up to movement when the Shields parameter(Θ) is larger than 0.8–1.0. The effective Nikuradse roughness on the mobile plan bed was derived indirectly from the erosion depth correlated to the mobile plan bed thickness considering the mass conservation in the present study. The proposed erosion depth confirmed the relation to the Shields parameters with an extra factor consisting of suspended sediment and its damping to turbulence. The decrement of the erosion depth caused by the increment of the sediment diameter at large shear stress was obtained, which was usually absent in classical empirical formulas based on the bedload theory. Good agreement with experiments was achieved by the present prediction of the Nikuradse roughness, erosion depth and sediment transport rate. Discussion was mainly focused on the prediction improvement caused by considering the impact of suspended sediment and its damping to turbulence.

A Survey of Research on Treatment of Pediatric Diarrhea with Massage Ying-Ming

Pediatric diarrhea is a common pediatric disease.Massage has broad application prospects in the treatment of pediatric diarrhea,which is an ideal treatment for pediatric diarrhea.In this paper,the etiology analysis of pediatric diarrhea,classification of traditional Chinese medicine(TCM),massage techniques and other aspects were reviewed.In order to provide reference for the clinical application of pediatric massage in the treatment of diarrhea.

Theoretical System of Sandstone-Type Uranium Deposits in Northern China

Many theoretical results on sandstone-type uranium mineralization in northern China obtained by the uranium research team of the Tianjin Center of Geological Survey in recent years are presented.From the source sink system of uranium-producing basins,sedimentary environment of uranium-bearing rock series,ore-forming fluid information,evolution of tectonic events,basin formation and development,we redefine and classify uranium orebodies,redox zoning,and ore-controlling structural styles.We then systematically propose a theoretical system of sandstone-type uranium deposits in northern China.We conclude that sandstone-type uranium deposits in northern China are mainly found in sedimentary environments such as rivers,deltas,and alluvial fans in the Mesozoic and Cenozoic lowstand systems tract and in gray sandstone layers in the vertical redox zoning.The orebodies are controlled by the tectonic slope belt,which is in the shape of a strip on the plane,and spreads in a layer or plate on the section.Vertical(ups and downs)tectonic movement triggers large-scale phreatic flow in the basin,which is the real driving force for controlling the ore-forming fluid.The theoretical system of sandstone-type uranium deposits in northern China should be based on global tectonic movement and environmental changes and take into account factors such as basins as a unit to study mineralization background,ore concentration areas as objects to study mineralization,and the correlation between regional tectonic movement and metallogenic process as a breakthrough point to study tectonic events and metallogenic events.It should also be based on different basin types to establish metallogenic models.The innovative research results and ideas are summarized with the aim of promoting the continuous improvement of sandstone-type uranium mineralization theory in northern China.

CHARACTERISTICS OF THE INTERANNUAL AND INTERDECADAL TIMESCALES OF EVAPORATION IN NORTHERN CHINA IN THE RECENT 115 YEARS

Evaporation plays an important role in water balance on the land surface. In Northern China, the evaporation series of the recent 115 years was reconstructed on the basis of Yhornthwaite evaporation formula. The characteristics of the reconstructed series were analyzed using 10-year running mean filter, power spectrum method, and running t-text of abrupt changes on the paper. The results showed that there were remarkable interannual fluctuations with timescales of about quasi-8-year, 3-4-year, and quasi-2-year, and interdecadal oscillations with timescales of 57.5-year, quasi-23-year, and l l.5-year. Meanwhile, the abrupt changes of the evaporation series were also of interdecadal timescale. Either interannual fluctuations or interdecadal oscillations of evaporation were closely related to variations in air temperatures and precipitation.

Caloric evaporation of the brine in Zangnan Salt Lake

Zangnan Salt Lake on the south of the Tibet is a type of carbonate lake with high concentrations of lithium,boron,and potassium and obviously it differs from seawater in its chemical composition.An experimental simulation of the caloric evaporation of the lake’s brine was conducted byfirst freezing the brine and then performing isothermal evaporation at 288.15 K.The freezing path and the physicochemical properties of the brine were determined.The crystallization sequence was natron,hydrohalite,halite,sylvite,zabuyelite,trona,aphthitalite,thermonatrite,and borax.Rubidium and cesium salts did not crystallized out but concentrated in the mother solution.The physicochemical properties(density,refractive index,conductivity,and pH)of the liquid phase changed as the evaporation progressed.In the beginning of the evaporation processes,the concentration of potassium ions in the liquid phase gradually increased but later it decreased.A peak value of 55.21 g/L was obtained when the evaporation was 88%complete.When the mineral aphthitalite began to crystallize;the concentra-tions of B2O3,Li+,Rb+,and Cs+gradually increased as the evaporation progressed.When the evaporation was 98%complete,their concentrations in the mother liquor were 40.77 g/L,4.838 g/L,400.17 mg/L and 31.95 mg/L,respectively.This essential fundamental study can provide an important reference for the comprehensive utilization of brines in Zangnan Salt Lake.

A MODEL OF TWO-PHASE EQUILIBRIUM FOR FORMATION OF KINK-BANDS IN ROCKS

Kink-bands in rocks have been widely observed in nature and imitated in the laboratory, and the mechanism of their formation has attracted much attention from various researchers for many years. In this paper, a two-phase equilibrium model is presented in which the kink-bands are considered as a high-strain phase and the other regions outside kink-bands as a low-strain phase and the discontinuity of the deformation gradient and stresses is permitted across the interface between those two phases. Based on the present model, we conduct the analysis for the rocks under plane strain compression by finding the minimum value of the compressive loading at which the governing equations have real, physically acceptable solutions. It is revealed that for the rocks with strain-softening behaviour, two-phase equilibrium solutions exist, and the critical value of the compressive loading, the inclination angle of the kink-band, and the stresses and strains inside and outside kink-bands can all be determined by the solution, which are in good agreement with experimental measurements and observations.

Biosafety and biosecurity in the era of synthetic biology:Meeting the challenges in China and the U.S.

On July 26,2019,the workshop “Biosafety and Biosecurity in the Era of Synthetic Biology:Meeting the Challenges in China and the U.S.”,co-hosted by Johns Hopkins Center for Health Security and Tianjin University Centre for Biosafety Research&Strategy,was held in Washington,D.C.of the United States.The goal of this workshop was to bring technical and policy experts from China and the U.S.,as well as experts from Europe,together to develop a mutual understanding of each country’s current governance structures and to begin a dialogue on what is required to promote global biosafety and biosecurity.