Magmatic-tectonic response of the South China Craton to the Paleo-Pacific subduction during the Triassic:a new viewpoint based on Well NK-1

The Nansha Block(NB)is one of the blocks separated from the southern margin of the South China Craton(SCC)by the western Pacific subduction,which contains rich information of geodynamic and tectonic transformation.To reveal the essence of western Paleo-Pacific subduction during the Triassic period,Well NK-1 in this block was selected for petrographic study,and published research data from other cooperative teams were compared.A double-cycle pattern of basic to neutral magmatic volcanism was established,and 36 lithological rhythmic layers and representative cryptoexplosive breccia facies and welded tuff bands were identified.Combined with a reanalysis of published geochronological data,geochemical elements,and isotope geochemistry,we found that the rock assemblages could be divided into an intermediate-acid dacite(DA)series(SiO_(2)>65%)and basaltic(BA)series(Co<40μg/g),which was formed during the early Late Triassic((218.6±3.2)–(217.9±3.5)Ma).BA exhibits obvious calc-alkaline island-arc magmatic properties:(^(87)Sr/^(86)Sr)_i ratio ranging 0.70377–0.71118(average:0.70645),^(147)Sm/^(144)Nd ratio ranging 0.119–0.193(average:0.168),and chondrite-normalized rare earth element(REE)curves being flat,while DA exhibits remarkable characteristics of subducted island-arc andesitic magma:(^(87)Sr/^(86)Sr)_i ratio(0.70939–0.71129;average:0.71035),εNd(t)value(-6.2–-4.8;average:-5.6)andε_(Hf)(t)value(-2.9–-1.7,average:-2.2)show obvious crust-mantle mixing characteristics.BA and DA reveal typical characteristics of island-arc magma systems and typeⅡenriched mantle(EM-Ⅱ)magma.BA magma was likely resulted from the process whereby the continental crust frontal accretionary wedge was driven by the Paleo-Pacific slab subduction into the deep and began to melt,resulting in a large amount of melt(fluid)joined the asthenosphere on the side of the continental margin.In contrast,DA magma was likely resulted from the process whereby the plate front was forced to bend with increasing subduction distance,which triggered the upwelling of the asthenosphere near the continent and subsequently led to the partial melting of the lithospheric mantle and lower crust due to continuous underplating.The lithospheric thinning environment in the study area at the end of Triassic created suitable conditions for the separation between the NB and SCC,which provided an opportunity for the formation of the early intracontinental rift during the later expansion of the South China Sea(SCS).

Chinese Stroke Association guidelines for clinical management of ischaemic cerebrovascular diseases:executive summary and 2023 update

Background China is one of the countries with the highest burden of stroke.Implementing multidimensional management guidelines will help clinicians practise evidence-based care,improve patient outcomes and alleviate societal burdens.This update of the 2019 edition will provide the latest comprehensive recommendations for the diagnosis and treatment of ischaemic cerebrovascular diseases.Methods We conducted a comprehensive search on MEDLINE(via PubMed)up to 31 August 2023.The writing team established the recommendations through multiple rounds of online and offline discussions.Each recommendation was graded using the evidence grading algorithm developed by the Chinese Stroke Association(CSA).The draft was reviewed and finalised by the CSA Stroke Guidelines Writing Committee.Results This update included revisions of 15 existing recommendations and 136 new recommendations in the following areas of stroke care:emergency assessment and diagnosis of ischaemic cerebrovascular disease,acute-phase reperfusion therapy,evaluation of underlying mechanisms,antithrombotic therapy,prevention and treatment of complications,and risk factor management.Conclusions This guideline updated the recommendations for the clinical management of ischaemic cerebrovascular disease from 2019.

Organophosphate Esters in Air and Seawater of the South China Sea:Spatial Distribution,Transport,and Air−Sea Exchange

Organophosphate esters(OPEs)have become one group of chemicals with emerging concern in the marine environment.In this work,we investigated OPEs in the air and seawater of the South China Sea in summer 2019.The concentrations of∑_(10)OPEs in the atmosphere ranged from 66 to 550 pg/m^(3),with TCIPP,TNBP,TPhP,and TEP predominating in the air.The total dissolved OPE concentrations(∑_(10)OPEs without TEP)measured in high-volume water samples ranged from 300 to 3600 pg/L,with a mean concentration of 1180±910 pg/L.TEP was measured with liquid−liquid extraction(LLE),and it showed the highest concentration(average 2000±1450 pg/L)among the selected OPEs.Total suspended matter associated OPEs accounted for less than 4.7%of the sum of OPE concentrations in seawater.Fugacity fractions and air−sea exchange fluxes showed that TCEP,TCIPP,TIBP,TEHP,TPhP,and EHDPP were favored to volatilize,TEP dominated the deposition,while TPrP and TNBP varied between volatilization and deposition.Atmospheric particle deposition fluxes ranged from 5 to 71 ng/m^(2)/day with an average of 17±15 ng/m^(2)/day.The input of∑OPEs to the entire South China Sea via atmospheric particle deposition was estimated to be 22±19 tons/year,while the net air−sea exchange fluxes of OPEs were volatilization from seawater to air with an average of 44±33 tons/year.This work suggests that air−sea exchange and atmospheric particle deposition are significant processes interfering with the transport of OPEs in the marine environment.

Chinese Stroke Association guidelines for clinical management of cerebrovascular disorders: executive summary and 2019 update of clinical management of ischaemic cerebrovascular diseases

Aim Stroke is the leading cause of disability and death in China.Ischaemic stroke accounts for about 60%-80%of all strokes.It is of considerable significance to carry out multidimensional management of ischaemic cerebrovascular diseases.This evidence-based guideline aims to provide the latest detailed and comprehensive recommendations on the diagnosis,treatment and secondary prevention of ischaemic cerebrovascular diseases.Methods We had performed comprehensive searches of MEDLINE(via PubMed)(before 30 June 2019),and integrated the relevant information into charts and distributed to the writing group.Writing group members discussed and determined the recommendations through teleconference.We used the level of evidence grading algorithm of Chinese Stroke Association to grade each recommendation.The draft was reviewed by the Guideline Writing Committee of Chinese Stroke Association Stroke and finalised.This guideline is fully updated every 3 years.results This evidence-based guideline is based on the treatment,care and prevention of ischaemic cerebrovascular diseases,which emphasises on pathogenesis evaluation,intravenous thrombolysis,endovascular therapy,antiplatelet therapy,prevention and treatment of complications,and risk factor management.Conclusions This updated guideline presents a framework for the management of ischaemic cerebrovascular diseases.Timely first-aid measures,professional care in the acute stage,and proactive secondary prevention will be helpful to patients.

Organic Matters and Lipid Biomarkers in Surface Sediments from the Northern South China Sea:Origins and Transport

In this study, content and distribution of organic matters （OM） and lipid biomarkers in surface sediments from northern South China Sea （SCS） were identified to reveal the sources and transport of fine-grained sediments. Organic matters and lipid biomarkers exhibited distinct spatial variation in northern SCS. Terrestrial discharge from the Pearl River and some mountainous rivers in southwestern Taiwan may contribute to the relatively high organic matters in the corresponding sea areas. The detection of unsaturated fatty acid homologues suggested the algal and/or bacterial OM contribution to surface sediments. The composites and distribution of lipid biomarkers indicate their mixed sources from terrestrial plants, marine algae and bacterial. Together with the proof of clay min- eral composites in the sediments, the results suggested that the currents, including the Guangdong Coastal Current and Kuroshio Current, control the transport and distribution of terrestrial sediment and the sedimentary environment in the northern SCS.

中国南海南科1井新近纪-第四纪生物礁磁性地层年代学

The tropical reef ecosystems are created by living organisms,such as corals and algae,and provide important habitats for millions of people and a variety of marine life,which have been severely threatened by climate changes over the past decades[1].These biogenic reefs account for a quarter of global CaCO_(3)production and thus are critical to global carbon cycling[2,3].

High-resolution MRI of intracranial large artery diseases:how to use it in clinical practice?

High-resolution MRI(HRMRI)has emerged as a useful tool for clinical research in recent years.Compared with traditional cranial and vessel imaging,HRMRI provides more additional valuable pathophysiology information that is helpful for the differential diagnosis of intracranial atherosclerosis,dissection and vasculitis.However,there are some points that a neurologist should keep in mind.First,although enhanced vessel wall imaging is widely applied for research purposes,it is not appropriate for routine clinical use.Any injury or inflammation within vessel wall can result in enhancement,which is unspecific for a diagnosis.Second,although plaque components identified on HRMRI arouse researchers’interest,they may have limited positive predictive value for future stroke.Ruptured plaques may have higher prevalence in asymptomatic patients than expected.More prospective observational studies are required.Third,the vessel wall morphology features remain the useful and reliable clue for a diagnosis.It is true that eccentric vessel wall lesions most likely represent atherosclerosis if vessel dissection is easily excluded.For concentric wall lesions,however,the underlying pathophysiology is complicated,either atherosclerotic or non-atherosclerotic.Fourth,HRMRI can show luminal thrombus directly and provide valuable details.All in all,when HRMRI is used by a neurologist,it should not be viewed as the only key for a diagnosis.The diagnosis should be made based on patient history,lab works,other imaging technique and even genetic examinations.

Bioaccumulation and changes of trace metals over the last two decades in marine organisms from Guangdong coastal regions, South China

Trace metal(Cr, Ni, Cu, Zn, Cd and Pb) exposures, distribution and bioaccumulation were investigated in marine organisms from Guangdong coastal regions, South China. The results showed that all of the selected metals were observed in marine organisms with a predomination of Cu and Zn. The metal exposure levels exhibited obvious variations between species with the decreasing order of crab > shellfish > shrimp > fish. The higher metals enrichment seen in shellfish and crab species primarily attributed to their living habits and the higher sediment background values of trace metals. Endpoint bioaccumulation factor(BAFfd) was used to characterize the bioaccumulation potentials of marine organisms to trace metals, of which Cu and Zn were the most accumulated elements. The exposure of trace metals in the cultured organisms was far lower than those in wild marine organisms, which is probably due to the effect of growth dilution. Comparisons with previous studies demonstrated that the concentration profiles of most trace metals declined over the last one to two decades, except Cu, that increased indistinctively.

Non-invasive assessment of intracranial wall shear stress using high-resolution magnetic resonance imaging in combination with computational fluid dynamics technique

In vivo studies on association between wall shear stress(WSS)and intracranial plaque are deficient.Based on the three-dimensional T1-weighted high-resolution magnetic resonance imaging(3DT1 HR-MRI)data of patients with low-grade stenotic(<50%)atherosclerotic middle cerebral artery(MCA)and subjects with normal MCA,we built a three-dimensional reconstructed WSS model by computational fluid dynamics(CFD)technique.Three-dimensional registration of the CFD model to the HR-MRI was performed with projections based on the resolution and thickness of the images.The relationships between the Wss at each side of the vessel wall and plaque location were analyzed.A total of 94 MCA plaques from 43 patients and 50 normal MCAs were analyzed.In the normal MCAs,WSS was lower at the ventral-inferior wall than at the dorsal-superior wall(proximal segment,p<0.001;middle segment,p<0.001)and lower at the inner wall than at the outer wall of the MCA curve(p<0.001).In atherosclerotic MCAs,similar low Wss regions were observed where plaques developed.The WSS ratio of the ventral-inferior wall to the dorsal-superior wall in atherosclerotic MCAs was lower than that in normal MCAs(p=0.002).The WSS_(inmer-outer)ratio in atherosclerotic MCAs was lower than that in normal MCAs(p=0.002).Low WSS was associated with MCA atherosclerosis formation and occurred mainly at the ventral inferior wall,which was anatomically opposite the orifices of penetrating arteries,and at the inner wall of the MCA curve.Overall,the results were well consistent with the low WSS theory in atherosclerosis formation.The reconstructed WSS model is a promising novel method for assessing an individualized vascular profile once validated by further studies.