As one of the participants in the Subseasonal to Seasonal(S2S)Prediction Project,the China Meteorological Administration(CMA)has adopted several model versions to participate in the S2S Project.This study evaluates th...As one of the participants in the Subseasonal to Seasonal(S2S)Prediction Project,the China Meteorological Administration(CMA)has adopted several model versions to participate in the S2S Project.This study evaluates the models’capability to simulate and predict the Madden-Julian Oscillation(MJO).Three versions of the Beijing Climate Center Climate System Model(BCC-CSM)are used to conduct historical simulations and re-forecast experiments(referred to as EXP1,EXP1-M,and EXP2,respectively).In simulating MJO characteristics,the newly-developed high-resolution BCC-CSM outperforms its predecessors.In terms of MJO prediction,the useful prediction skill of the MJO index is enhanced from 15 days in EXP1 to 22 days in EXP1-M,and further to 24 days in EXP2.Within the first forecast week,the better initial condition in EXP2 largely contributes to the enhancement of MJO prediction skill.However,during forecast weeks 2–3,EXP2 shows little advantage compared with EXP1-M because the increased skill at MJO initial phases 6–7 is largely offset by the degraded skill at MJO initial phases 2–3.Particularly at initial phases 2–3,EXP1-M skillfully captures the wind field and Kelvin-wave response to MJO convection,leading to the highest prediction skill of the MJO.Our results reveal that,during the participation of the CMA models in the S2S Project,both the improved model initialization and updated model physics played positive roles in improving MJO prediction.Future efforts should focus on improving the model physics to better simulate MJO convection over the Maritime Continent and further improve MJO prediction at long lead times.展开更多
This study focuses on model predictive skill with respect to stratospheric sudden warming(SSW) events by comparing the hindcast results of BCC_CSM1.1(m) with those of the ECMWF's model under the sub-seasonal to se...This study focuses on model predictive skill with respect to stratospheric sudden warming(SSW) events by comparing the hindcast results of BCC_CSM1.1(m) with those of the ECMWF's model under the sub-seasonal to seasonal prediction project of the World Weather Research Program and World Climate Research Program. When the hindcasts are initiated less than two weeks before SSW onset, BCC_CSM and ECMWF show comparable predictive skill in terms of the temporal evolution of the stratospheric circumpolar westerlies and polar temperature up to 30 days after SSW onset. However, with earlier hindcast initialization, the predictive skill of BCC_CSM gradually decreases, and the reproduced maximum circulation anomalies in the hindcasts initiated four weeks before SSW onset replicate only 10% of the circulation anomaly intensities in observations. The earliest successful prediction of the breakdown of the stratospheric polar vortex accompanying SSW onset for BCC_CSM(ECMWF) is the hindcast initiated two(three) weeks earlier. The predictive skills of both models during SSW winters are always higher than that during non-SSW winters, in relation to the successfully captured tropospheric precursors and the associated upward propagation of planetary waves by the model initializations. To narrow the gap in SSW predictive skill between BCC_CSM and ECMWF, ensemble forecasts and error corrections are performed with BCC_CSM. The SSW predictive skill in the ensemble hindcasts and the error corrections are improved compared with the previous control forecasts.展开更多
This paper describes a strategy for merging daily precipitation information from gauge observations, satellite estimates （SEs）, and numerical predictions at the global scale. The strategy is designed to remove syste...This paper describes a strategy for merging daily precipitation information from gauge observations, satellite estimates （SEs）, and numerical predictions at the global scale. The strategy is designed to remove systemic bias and random error from each individual daily precipitation source to produce a better gridded global daily precipitation product through three steps. First, a cumulative distribution function matching procedure is performed to remove systemic bias over gauge-located land areas. Then, the overall biases in SEs and model predictions （MPs） over ocean areas are corrected using a rescaled strategy based on monthly precipitation. Third, an optimal interpolation （OI）-based merging scheme （referred as the HL-OI scheme） is used to combine unbiased gahge observations, SEs, and MPs to reduce random error from each source and to produce a gauge--satellite-model merged daily precipitation analysis, called BMEP-d （Beijing Climate Center Merged Estimation of Precipitation with daily resolution）, with complete global coverage. The BMEP-d data from a four-year period （2011- 14） demonstrate the ability of the merging strategy to provide global daily precipitation of substantially improved quality. Benefiting from the advantages of the HL-OI scheme for quantitative error estimates, the better source data can obtain more weights during the merging processes. The BMEP-d data exhibit higher consistency with satellite and gauge source data at middle and low latitudes, and with model source data at high latitudes. Overall, independent validations against GPCP-1DD （GPCP one-degree daily） show that the consistencies between B MEP-d and GPCP-1DD are higher than those of each source dataset in terms of spatial pattern, temporal variability, probability distribution, and statistical precipitation events.展开更多
In this study,we evaluate the forecast skill of the subseasonal-to-seasonal(S2S)prediction model of the Beijing Climate Center(BCC)for the boreal summer intraseasonal oscillation(BSISO).We also discuss the key factors...In this study,we evaluate the forecast skill of the subseasonal-to-seasonal(S2S)prediction model of the Beijing Climate Center(BCC)for the boreal summer intraseasonal oscillation(BSISO).We also discuss the key factors that inhibit the BSISO forecast skill in this model.Based on the bivariate anomaly correlation coefficient(ACC)of the BSISO index,defined by the first two EOF modes of outgoing longwave radiation and 850-hPa zonal wind anomalies over the Asian monsoon region,we found that the hindcast skill degraded as the lead time increased.The ACC dropped to below 0.5for lead times of 11 days and longer when the predicted BSISO showed weakened strength and insignificant northward propagation.To identify what causes the weakened forecast skill of BSISO at the forecast lead time of 11 days,we diagnosed the main mechanisms responsible for the BSISO northward propagation.The same analysis was also carried out using the observations and the outputs of the four-day forecast lead that successfully predicted the observed northward-propagating BSISO.We found that the lack of northward propagation at the 11-day forecast lead was due to insufficient increases in low-level cyclonic vorticity,moistening and warm temperature anomalies to the north of the convection,which were induced by the interaction between background mean flows and BSISO-related anomalous fields.The BCC S2S model can predict the background monsoon circulations,such as the low-level southerly and the northerly and easterly vertical shears,but has limited capability in forecasting the distributions of circulation and moisture anomalies.展开更多
The El Niño-Southern Oscillation(ENSO)ensemble prediction skills of the Beijing Climate Center(BCC)climate prediction system version 2(BCC-CPS2)are examined for the period from 1991 to 2018.The upper-limit ENSO p...The El Niño-Southern Oscillation(ENSO)ensemble prediction skills of the Beijing Climate Center(BCC)climate prediction system version 2(BCC-CPS2)are examined for the period from 1991 to 2018.The upper-limit ENSO predictability of this system is quantified by measuring its“potential”predictability using information-based metrics,whereas the actual prediction skill is evaluated using deterministic and probabilistic skill measures.Results show that:(1)In general,the current operational BCC model achieves an effective 10-month lead predictability for ENSO.Moreover,prediction skills are up to 10–11 months for the warm and cold ENSO phases,while the normal phase has a prediction skill of just 6 months.(2)Similar to previous results of the intermediate coupled models,the relative entropy(RE)with a dominating ENSO signal component can more effectively quantify correlation-based prediction skills compared to the predictive information(PI)and the predictive power(PP).(3)An evaluation of the signal-dependent feature of the prediction skill scores suggests the relationship between the“Spring predictability barrier(SPB)”of ENSO prediction and the weak ENSO signal phase during boreal spring and early summer.展开更多
Background: Histone deacetylase inhibitors (HDACI) are promising class of drugs acting as antiproliferative agents by promoting differentiation as well as inducing apoptosis. Vorinostat (suberoylanilide hydroxamic aci...Background: Histone deacetylase inhibitors (HDACI) are promising class of drugs acting as antiproliferative agents by promoting differentiation as well as inducing apoptosis. Vorinostat (suberoylanilide hydroxamic acid, SAHA) is the first among this new class of anticancer drugs to be approved by FDA for the treatment of cancer but only for cutaneous T cell lymphoma (CTCL). The objective of this study is to investigate the inhibitory effect of SAHA on the viability of human bladder cancer cells and its synergetic effect with chemotherapy agents in vitro and in vivo. Methods: The cell viability of human bladder cancer cell lines after treated with SAHA or SAHA combining mitomycin c (MMC), Cisplatin (DDP) and Adriamycin (ADM) were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Hoechst staining was used to observe cell morphology for apoptotic cells. The survivin protein and acetylated histone H3 levels in bladder cancer were quantified by Western blot analysis. In vivo tumor growth inhibition of intravesical inject SAHA was determined in rats with N-methyl-N-nitrosourea (MNU) induced bladder cancer. Results: SAHA significantly inhibited growth of bladder cancer cell lines with concentration and time dependent manner. Furthermore, better results of tumor inhibition would be achieved when it was combined with chemotherapeutic agents in vitro and in vivo. Survivin expression decreased and acetylated histone H3 expression increased in bladder cancer cells lines after SAHA treatment. Intravesically injections of SAHA can inhibit tumor progress when combined with DDP. Conclusions: SAHA can act as HDACI which has direct anti-cancer effect and can enhance the action of several chemotherapy agents markedly. SAHA may sensitize bladder cancer to anti cancer drugs by down regulating survivin expression. Intravesically injections of SAHA can prevent tumor progression in MNU induced bladder cancer.展开更多
The safety of nanoparticle-based drug delivery systems(DDSs)for cancer treatment is still a challenge,restricted by the intrinsic cytotoxicity of drug carriers and leakage of loaded drug.Here,we propose a novel nanoca...The safety of nanoparticle-based drug delivery systems(DDSs)for cancer treatment is still a challenge,restricted by the intrinsic cytotoxicity of drug carriers and leakage of loaded drug.Here,we propose a novel nanocarrier’s cytotoxicity avoidance strategy by synthesizing an encapsulation core–shell structure of zeolitic imidazolate framework-8(ZIF-8)-based colloid particles(CPs)with an amorphous ZIF-8 skin.This encapsulation structure achieves an ultra-high loading rate(LR)of 90%(i.e.,9 mg doxorubicin(DOX)per 1 mg ZIF-8)for DOX and the protection of DOX from leaking.Notably,to deliver unit-dose drug,this ultra-high LR of 90%significantly reduces the usage of ZIF-8 to 1.2%(2 orders of magnitude)compared to that of DOX@ZIF-8 with a 10%LR,in which cytotoxicity of ZIF-8 could well below the safety limit and then be relatively ignored.Safety,drug delivery efficacy,scale-up ability,and universality of this encapsulation structure have been further verified.Our findings suggest the great potential of this ZIF-8-based encapsulation core–shell structure in the field of drug delivery.展开更多
DNA is highly vulnerable to spontaneous and environmental timely damage in living cells.DNA damage may cause genetic instability and increase cancer risk if the damages are not repaired timely and efficiently.Human ce...DNA is highly vulnerable to spontaneous and environmental timely damage in living cells.DNA damage may cause genetic instability and increase cancer risk if the damages are not repaired timely and efficiently.Human cells possess several DNA damage response(DDR)mechanisms to protect the integrity of their genome.Clarification of the mechanisms under-lying the DNA damage response following lethal damage will facilitate the identification of therapeutic targets for cancers.Histone post-translational modifications(PTMs)have been indicated to play different roles in the repair of DNA damage.In this context,histone PTMs regulate recruitment of downstream effectors,and facilitate appropriate repair response.This review outlines the current understanding of different histone PTMs in response to DNA dam-age repair,besides,enumerates the role of new type PTMs such as histone succinylation and crotonylation in regulating DNA damage repair processes.展开更多
There are increasing concerns about the environmental impact of rising atmospheric carbon monoxide concentrations,thus it is necessary to develop new catalysts for efficient CO oxidation.Based on first-principles calc...There are increasing concerns about the environmental impact of rising atmospheric carbon monoxide concentrations,thus it is necessary to develop new catalysts for efficient CO oxidation.Based on first-principles calculations,the potential ofγ-graphyne(GY)as substrate for metals in the 4th and 5th periods under single-atom and dual-atoms concentration modes has been systematically investigated.It was found that single-atom Co,Ir,Rh,and Ru could effectively oxidate CO molecules,especially for single Rh.Furthermore,proper atoms concentration could boost the CO oxidation activity by supplying more reaction centers,such as Rh^(2)/GY.It was determined that two Rh atoms in Rh^(2)/GY act different roles in the catalytic reaction:one structural and another functional.Screening tests suggest that substituting the structural Rh atom in the center of acetylenic ring by Co or Cu atom is a possible way to maintain the reaction performance while reducing the noble metal cost.This systemic investigation will help in understanding the fundamental reaction mechanisms on GY-based substrates.We emphasize that properly exposed frontier orbital of functional metal atom is crucial in adsorption configuration as well as entire catalytic performance.This study constructs a workflow and provides valuable information for rational design of CO oxidation catalysts.展开更多
The size of the gold particles is a very important parameter to get active catalysts.This paper reports a novel colloidal deposition method to prepare Au/LaVO_(4)nanocomposite catalyst with monodispersed Au colloids a...The size of the gold particles is a very important parameter to get active catalysts.This paper reports a novel colloidal deposition method to prepare Au/LaVO_(4)nanocomposite catalyst with monodispersed Au colloids and uniform LaVO_(4)nanoplates in nonpolar solvent.Monodispersed Au colloids with tunable size(such as 2,5,7,11,13,and 16 nm)and LaVO_(4)nanocrystals with well-defi ned shapes were pre-synthesized assisted with oleic acid/amine.During the following immobilization process,the particle size and shape of Au and LaVO_(4)were nearly preserved.As-prepared Au/LaVO_(4)nanocomposite showed high catalytic activity for CO oxidation at room temperature.Since sizes of gold particles were well-defi ned before the immobilization process,size effect of gold particles was easy to be investigated and the results show that 5-nm Au/LaVO_(4)nanocomposite has the highest activity for CO oxidation.This synthetic method can be extended further for the preparation of other composite nanomaterials.展开更多
Omphacite microstructures are important to decipher the metamorphic pressuretemperature(P-T)conditions of eclogite during subduction and exhumation processes.Here we present a systematic microstructural investigation ...Omphacite microstructures are important to decipher the metamorphic pressuretemperature(P-T)conditions of eclogite during subduction and exhumation processes.Here we present a systematic microstructural investigation of omphacite using transmission electron microscopy(TEM)in an ultrahigh-pressure(UHP)eclogite sample from Shuanghe,Dabie orogen,China.The omphacite can be divided into two phases:(1)Omp-1,exhibits as the main part of omphacite with P2/n space group containing small amount of dislocations and numerous antiphase domains(APDs).(2)Omp-2,shows as banded subgrains with C2/c space group containing large amount of dislocations.These two phases of omphacite have almost the same crystallography orientation and bounded by dislocation walls.Along these dislocation walls,we found some barroisite and albite microcrystals.The barroisite microcrystals contain large amount of dislocations and show a topological relation with host omphacite.While the albite microcrystals contain small amount of dislocations and does not show topological relation with host.These microstructures could give us the following metamorphic information to constrain the P-T path of eclogite:Firstly,this two omphacite space groups should be evolved from the same precursor C2/c omphacite,which had been underwent strongly plastic deformation during the syn-to late-peak metamorphic stage.Secondly,the precursor C2/c omphacite began to be retrograded and altered by small amount of barroisite microcrystals along its dislocation walls under the P-T condition of 2.2–2.6 GPa and 650–700℃ at the early amphibole eclogite stage.Thirdly,large amount of Na and other elements were exsolved from some precursor C2/c omphacite subgrains and crystallized numerous albite microcrystals at their boundaries,which is the necessary for the space group of C2/c surviving under the lower P-T conditions(1.7–1.9 GPa and 630–690 C)during the middle amphibole eclogite stage.Lastly,the rest of precursor C2/c omphacite subgrains were transformed into P2/n polymorph and formed the APDs structures under the P-T condition of^1.5 GPa and 650–680℃ during the late amphibole eclogite stage.展开更多
High yield production of phenol from hydroxylation of benzene with low energy consumption is of paramount importance,but still challenging.Herein,a new strategy,consisting of using diatomic synergistic modulation(DSM)...High yield production of phenol from hydroxylation of benzene with low energy consumption is of paramount importance,but still challenging.Herein,a new strategy,consisting of using diatomic synergistic modulation(DSM)to effectively control the separation of photo-generated carriers for an enhanced production of phenol is reported.The atomic level dispersion of Fe and Cr respectively decorated on Al based MIL-53-NH_(2)photocatalyst(Fe1/Cr:MIL-53-NH_(2))is designed,in which Cr single atoms are substituted for Al3+while Fe single atoms are coordinated by N.Notably,the Fe1/Cr:MIL-53-NH_(2)significantly boosts the photooxidation of benzene to phenol under visible light irradiation,which is much higher than those of MIL-53-NH_(2),Cr:MIL-53-NH_(2),Fe1/MIL-53-NH_(2),and Fe nanoparticles/Cr:MIL-53-NH_(2)catalysts.Theoretical and experimental results reveal that the Cr single atoms and Fe single atoms can act as electron acceptor and electron donor,respectively,during photocatalytic reaction,exhibiting a synergistic effect on the separation of the photo-generated carriers and thereby causing great enhancement on the benzene oxidation.This strategy provides new insights for rational design of advanced photocatalysts at the atomic level.展开更多
Intracrystalline distortions(like undulose extinction,dislocations,and subgrain boundaries)in olivine from naturally-deformed peridotites are generally taken as signs of dislocation creep.However,similar features in o...Intracrystalline distortions(like undulose extinction,dislocations,and subgrain boundaries)in olivine from naturally-deformed peridotites are generally taken as signs of dislocation creep.However,similar features in olivine phenocrysts that have been found in basaltic magmas are still not well understood.In particular,whether subgrain boundaries in olivine phenocrysts arise from plastic deformation or grain growth is still debated(in the latter case,they are essentially grain boundaries but not subgrain boundaries.Therefore,we used hereinafter subgrain-boundary-like structures instead of subgrain boundaries to name this kind of intracrystalline distortion).Here we carried out a detailed study on dislocations and subgrainboundary-like(SG-like)structures in olivine phenocrysts from two Hawaiian basaltic lavas by means of petrographic microscopy,scanning electron microscopy,and transmission electron microscopy(TEM).Abundant and complex dislocation substructures(free dislocations,dislocation walls,and dislocation tangles)were observed in the decorated olivine grains,similar to those in olivine from peridotite xenoliths entrained by the Hawaiian basalts.The measured average dislocation density is(2.9±1.3)×1011 m-2,and is three to five orders of magnitude higher than that in laboratory-synthesized,undeformed olivine.TEM observations on samples cut across the SG-like structures by FIB(focused ion beam)demonstrated that this kind of structures is made of an array of dislocations.These observations clearly indicate that these structures are real subgrain boundaries rather than grain boundaries.These facts suggest that the observed high dislocation densities and subgrain boundaries cannot result from crystal crystallization/growth,but can be formed by plastic deformation.These deformation features do not prove that the olivine phenocrysts(and implicitly mantle xenoliths)were deformed after their capture by the basaltic magmas,but can be ascribed to a former deformation event in a dunitic cumulate,which was formed by magmatic fractionation,then plastically deformed,and finally disaggregated and captured by the basaltic magma that brought them to the surface.展开更多
In the Nino3.4 region(tropical Pacific,5°S-5°N,170°-120°W),sea surface temperature(SST)changes are highly correlated with temperature variations in the upper 40-m layer.This study explores the uppe...In the Nino3.4 region(tropical Pacific,5°S-5°N,170°-120°W),sea surface temperature(SST)changes are highly correlated with temperature variations in the upper 40-m layer.This study explores the upper-ocean heat budget in the Nino3.4 region using Ocean Reanalysis System 5(ORAS5)monthly data from 1979 to 2018,with a focus on ocean heat transports at lateral boundaries in the top 40-m layer and their correlation with temperature variations.In the region,there is a well-defined structure of opposite meridional circulation in the upper and lower parts of the thermocline,characterized by divergence in the upper layer above 40 m and convergence in the lower layer.The change of mean temperature in the upper layer is determined by the sum of zonal,meridional,and vertical heat transports,which,however,tend to largely compensate for each other.In general,part of the surface heat flux from the atmosphere to the ocean and the heat transport from the subsurface ocean are transported out of the domain by meridional and zonal currents,leaving only a tiny part to warm or cool the upper ocean.The amplitude of the net surface heat flux effective for the entire 40-m layer of the ocean is weaker than the lateral heat transport.On an interannual timescale,variations of heat transports in both zonal and meridional are positively correlated with temperature anomalies,while the vertical heat transport from the subsurface ocean is negatively correlated.Composite analyses for five El Nino events and five La Nina events also revealed that there is a positive contribution of horizontal transport convergence to temperature anomalies during the evolution of El Nino(warming)and La Nina(cooling),while vertical transport acts against temperature variations.展开更多
Based on the empirical orthogonal function(EOF) analysis, the East Asia–Pacific(EAP) teleconnection is extracted as the leading mode of the subseasonal variability over East Asia in summer, with a meridional tripole ...Based on the empirical orthogonal function(EOF) analysis, the East Asia–Pacific(EAP) teleconnection is extracted as the leading mode of the subseasonal variability over East Asia in summer, with a meridional tripole structure and significant periods of 10–30 and 50–70 days. A two-dimensional phase–space diagram is established for the EAP index and its time tendency so as to monitor the real-time state of EAP events. Based on the phase composite analysis, the general circulation anomalies first occur over the high-latitude area of Europe centered near Novaya Zemlya at the beginning of EAP events. These general circulation anomalies then influence rainfall over Northeast China,North China, and the region south of the Yangtze River valley(YRV) as the phases of EAP event progress. The representation, predictability, and prediction skill of the EAP teleconnection are examined in the two fully coupled subseasonal prediction systems of the Beijing Climate Center(BCC) and UK Met Office(UKMO GloSea5). Both models are able to simulate the EAP meridional tripole over East Asia as the leading mode and its characteristics of evolution as well, except for the weaker precursors over Novaya Zemlya and an inconspicuous influence on precipitation over Northeast China. The actual prediction skill of the EAP teleconnection during May–September(MJJAS) is about 10 days in the BCC model and 15 days in the UKMO model based on correlation measures, but is higher when initialized from the EAP peak phases or when targeted on strong EAP scenarios. However, both of the ensemble prediction systems are under-dispersive and the predictable signals extend to 18 and 30 days in BCC and UKMO models based on signal-to-error metrics, indicating that there may be further scope for enhancing the capability of these models for the EAP teleconnection prediction and the associated impacts studies.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42075161).
文摘As one of the participants in the Subseasonal to Seasonal(S2S)Prediction Project,the China Meteorological Administration(CMA)has adopted several model versions to participate in the S2S Project.This study evaluates the models’capability to simulate and predict the Madden-Julian Oscillation(MJO).Three versions of the Beijing Climate Center Climate System Model(BCC-CSM)are used to conduct historical simulations and re-forecast experiments(referred to as EXP1,EXP1-M,and EXP2,respectively).In simulating MJO characteristics,the newly-developed high-resolution BCC-CSM outperforms its predecessors.In terms of MJO prediction,the useful prediction skill of the MJO index is enhanced from 15 days in EXP1 to 22 days in EXP1-M,and further to 24 days in EXP2.Within the first forecast week,the better initial condition in EXP2 largely contributes to the enhancement of MJO prediction skill.However,during forecast weeks 2–3,EXP2 shows little advantage compared with EXP1-M because the increased skill at MJO initial phases 6–7 is largely offset by the degraded skill at MJO initial phases 2–3.Particularly at initial phases 2–3,EXP1-M skillfully captures the wind field and Kelvin-wave response to MJO convection,leading to the highest prediction skill of the MJO.Our results reveal that,during the participation of the CMA models in the S2S Project,both the improved model initialization and updated model physics played positive roles in improving MJO prediction.Future efforts should focus on improving the model physics to better simulate MJO convection over the Maritime Continent and further improve MJO prediction at long lead times.
基金supported by the National Key R&D Program of China (Grant Nos. 2016YFA0602104 and 2016YFA0602102)the National Natural Science Foundation of China (Grant Nos. 41705024, 41575041, 41705039 and 41705076)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA17010105)the Startup Foundation for Introducing Talent of NUIST (Grant No. 2016r060)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘This study focuses on model predictive skill with respect to stratospheric sudden warming(SSW) events by comparing the hindcast results of BCC_CSM1.1(m) with those of the ECMWF's model under the sub-seasonal to seasonal prediction project of the World Weather Research Program and World Climate Research Program. When the hindcasts are initiated less than two weeks before SSW onset, BCC_CSM and ECMWF show comparable predictive skill in terms of the temporal evolution of the stratospheric circumpolar westerlies and polar temperature up to 30 days after SSW onset. However, with earlier hindcast initialization, the predictive skill of BCC_CSM gradually decreases, and the reproduced maximum circulation anomalies in the hindcasts initiated four weeks before SSW onset replicate only 10% of the circulation anomaly intensities in observations. The earliest successful prediction of the breakdown of the stratospheric polar vortex accompanying SSW onset for BCC_CSM(ECMWF) is the hindcast initiated two(three) weeks earlier. The predictive skills of both models during SSW winters are always higher than that during non-SSW winters, in relation to the successfully captured tropospheric precursors and the associated upward propagation of planetary waves by the model initializations. To narrow the gap in SSW predictive skill between BCC_CSM and ECMWF, ensemble forecasts and error corrections are performed with BCC_CSM. The SSW predictive skill in the ensemble hindcasts and the error corrections are improved compared with the previous control forecasts.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41275076, 41305057, 41175066, 41175086, and 40905046)the Beijing Natural Science Foundation (Grant No. 8144046)+1 种基金the National High Technology Research and Development Program of China (Grant Nos. 2009AA122005 and 2009BAC51B03)the National Basic Research Program of China (Grant No. 2010CB 951902)
文摘This paper describes a strategy for merging daily precipitation information from gauge observations, satellite estimates （SEs）, and numerical predictions at the global scale. The strategy is designed to remove systemic bias and random error from each individual daily precipitation source to produce a better gridded global daily precipitation product through three steps. First, a cumulative distribution function matching procedure is performed to remove systemic bias over gauge-located land areas. Then, the overall biases in SEs and model predictions （MPs） over ocean areas are corrected using a rescaled strategy based on monthly precipitation. Third, an optimal interpolation （OI）-based merging scheme （referred as the HL-OI scheme） is used to combine unbiased gahge observations, SEs, and MPs to reduce random error from each source and to produce a gauge--satellite-model merged daily precipitation analysis, called BMEP-d （Beijing Climate Center Merged Estimation of Precipitation with daily resolution）, with complete global coverage. The BMEP-d data from a four-year period （2011- 14） demonstrate the ability of the merging strategy to provide global daily precipitation of substantially improved quality. Benefiting from the advantages of the HL-OI scheme for quantitative error estimates, the better source data can obtain more weights during the merging processes. The BMEP-d data exhibit higher consistency with satellite and gauge source data at middle and low latitudes, and with model source data at high latitudes. Overall, independent validations against GPCP-1DD （GPCP one-degree daily） show that the consistencies between B MEP-d and GPCP-1DD are higher than those of each source dataset in terms of spatial pattern, temporal variability, probability distribution, and statistical precipitation events.
基金supported by the National Basic Research Program of China (973 Program) (Grant No.2015CB453200)
文摘In this study,we evaluate the forecast skill of the subseasonal-to-seasonal(S2S)prediction model of the Beijing Climate Center(BCC)for the boreal summer intraseasonal oscillation(BSISO).We also discuss the key factors that inhibit the BSISO forecast skill in this model.Based on the bivariate anomaly correlation coefficient(ACC)of the BSISO index,defined by the first two EOF modes of outgoing longwave radiation and 850-hPa zonal wind anomalies over the Asian monsoon region,we found that the hindcast skill degraded as the lead time increased.The ACC dropped to below 0.5for lead times of 11 days and longer when the predicted BSISO showed weakened strength and insignificant northward propagation.To identify what causes the weakened forecast skill of BSISO at the forecast lead time of 11 days,we diagnosed the main mechanisms responsible for the BSISO northward propagation.The same analysis was also carried out using the observations and the outputs of the four-day forecast lead that successfully predicted the observed northward-propagating BSISO.We found that the lack of northward propagation at the 11-day forecast lead was due to insufficient increases in low-level cyclonic vorticity,moistening and warm temperature anomalies to the north of the convection,which were induced by the interaction between background mean flows and BSISO-related anomalous fields.The BCC S2S model can predict the background monsoon circulations,such as the low-level southerly and the northerly and easterly vertical shears,but has limited capability in forecasting the distributions of circulation and moisture anomalies.
基金The National Key Research and Development Program under contract No.2017YFA0604200the National Program on Global Change and Air-Sea Interaction under contract No.GASI-IPOVAI-06the National Natural Science Foundation of China under contract No.41530961.
文摘The El Niño-Southern Oscillation(ENSO)ensemble prediction skills of the Beijing Climate Center(BCC)climate prediction system version 2(BCC-CPS2)are examined for the period from 1991 to 2018.The upper-limit ENSO predictability of this system is quantified by measuring its“potential”predictability using information-based metrics,whereas the actual prediction skill is evaluated using deterministic and probabilistic skill measures.Results show that:(1)In general,the current operational BCC model achieves an effective 10-month lead predictability for ENSO.Moreover,prediction skills are up to 10–11 months for the warm and cold ENSO phases,while the normal phase has a prediction skill of just 6 months.(2)Similar to previous results of the intermediate coupled models,the relative entropy(RE)with a dominating ENSO signal component can more effectively quantify correlation-based prediction skills compared to the predictive information(PI)and the predictive power(PP).(3)An evaluation of the signal-dependent feature of the prediction skill scores suggests the relationship between the“Spring predictability barrier(SPB)”of ENSO prediction and the weak ENSO signal phase during boreal spring and early summer.
文摘Background: Histone deacetylase inhibitors (HDACI) are promising class of drugs acting as antiproliferative agents by promoting differentiation as well as inducing apoptosis. Vorinostat (suberoylanilide hydroxamic acid, SAHA) is the first among this new class of anticancer drugs to be approved by FDA for the treatment of cancer but only for cutaneous T cell lymphoma (CTCL). The objective of this study is to investigate the inhibitory effect of SAHA on the viability of human bladder cancer cells and its synergetic effect with chemotherapy agents in vitro and in vivo. Methods: The cell viability of human bladder cancer cell lines after treated with SAHA or SAHA combining mitomycin c (MMC), Cisplatin (DDP) and Adriamycin (ADM) were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Hoechst staining was used to observe cell morphology for apoptotic cells. The survivin protein and acetylated histone H3 levels in bladder cancer were quantified by Western blot analysis. In vivo tumor growth inhibition of intravesical inject SAHA was determined in rats with N-methyl-N-nitrosourea (MNU) induced bladder cancer. Results: SAHA significantly inhibited growth of bladder cancer cell lines with concentration and time dependent manner. Furthermore, better results of tumor inhibition would be achieved when it was combined with chemotherapeutic agents in vitro and in vivo. Survivin expression decreased and acetylated histone H3 expression increased in bladder cancer cells lines after SAHA treatment. Intravesically injections of SAHA can inhibit tumor progress when combined with DDP. Conclusions: SAHA can act as HDACI which has direct anti-cancer effect and can enhance the action of several chemotherapy agents markedly. SAHA may sensitize bladder cancer to anti cancer drugs by down regulating survivin expression. Intravesically injections of SAHA can prevent tumor progression in MNU induced bladder cancer.
基金supported by the National Natural Science Foundation of China(No.22101029)the Beijing Natural Science Foundation(No.2222006)+2 种基金the Beijing Municipal Financial Project BJAST Scholar Programs B(No.BS202001)the Beijing Municipal Financial Project BJAST Young Scholar Programs B(No.YS202202)the Beijing Municipal Financial Project BJAST Budding Talent Program(No.23CE-BGS-01).
文摘The safety of nanoparticle-based drug delivery systems(DDSs)for cancer treatment is still a challenge,restricted by the intrinsic cytotoxicity of drug carriers and leakage of loaded drug.Here,we propose a novel nanocarrier’s cytotoxicity avoidance strategy by synthesizing an encapsulation core–shell structure of zeolitic imidazolate framework-8(ZIF-8)-based colloid particles(CPs)with an amorphous ZIF-8 skin.This encapsulation structure achieves an ultra-high loading rate(LR)of 90%(i.e.,9 mg doxorubicin(DOX)per 1 mg ZIF-8)for DOX and the protection of DOX from leaking.Notably,to deliver unit-dose drug,this ultra-high LR of 90%significantly reduces the usage of ZIF-8 to 1.2%(2 orders of magnitude)compared to that of DOX@ZIF-8 with a 10%LR,in which cytotoxicity of ZIF-8 could well below the safety limit and then be relatively ignored.Safety,drug delivery efficacy,scale-up ability,and universality of this encapsulation structure have been further verified.Our findings suggest the great potential of this ZIF-8-based encapsulation core–shell structure in the field of drug delivery.
基金supported by National Natural Science Foundation of China(No.82071695,82060535)Natural Science Foundation of Gansu Province,China(No.21JR7RA450)。
文摘DNA is highly vulnerable to spontaneous and environmental timely damage in living cells.DNA damage may cause genetic instability and increase cancer risk if the damages are not repaired timely and efficiently.Human cells possess several DNA damage response(DDR)mechanisms to protect the integrity of their genome.Clarification of the mechanisms under-lying the DNA damage response following lethal damage will facilitate the identification of therapeutic targets for cancers.Histone post-translational modifications(PTMs)have been indicated to play different roles in the repair of DNA damage.In this context,histone PTMs regulate recruitment of downstream effectors,and facilitate appropriate repair response.This review outlines the current understanding of different histone PTMs in response to DNA dam-age repair,besides,enumerates the role of new type PTMs such as histone succinylation and crotonylation in regulating DNA damage repair processes.
基金This work was supported by the National Natural Science Foundation of China(Nos.22101029 and 21703219)Beijing Municipal Natural Science Foundation(No.2222006)+1 种基金Beijing Municipal Financial Project BJAST Scholar Programs B(No.BS202001)Beijing Municipal Financial Project BJAST Young Scholar Programs B(No.YS202202).
文摘There are increasing concerns about the environmental impact of rising atmospheric carbon monoxide concentrations,thus it is necessary to develop new catalysts for efficient CO oxidation.Based on first-principles calculations,the potential ofγ-graphyne(GY)as substrate for metals in the 4th and 5th periods under single-atom and dual-atoms concentration modes has been systematically investigated.It was found that single-atom Co,Ir,Rh,and Ru could effectively oxidate CO molecules,especially for single Rh.Furthermore,proper atoms concentration could boost the CO oxidation activity by supplying more reaction centers,such as Rh^(2)/GY.It was determined that two Rh atoms in Rh^(2)/GY act different roles in the catalytic reaction:one structural and another functional.Screening tests suggest that substituting the structural Rh atom in the center of acetylenic ring by Co or Cu atom is a possible way to maintain the reaction performance while reducing the noble metal cost.This systemic investigation will help in understanding the fundamental reaction mechanisms on GY-based substrates.We emphasize that properly exposed frontier orbital of functional metal atom is crucial in adsorption configuration as well as entire catalytic performance.This study constructs a workflow and provides valuable information for rational design of CO oxidation catalysts.
基金supported by NSFC(50372030)the state key project of fundamental research for nanomaterials and nanostructures(2003CB716901).
文摘The size of the gold particles is a very important parameter to get active catalysts.This paper reports a novel colloidal deposition method to prepare Au/LaVO_(4)nanocomposite catalyst with monodispersed Au colloids and uniform LaVO_(4)nanoplates in nonpolar solvent.Monodispersed Au colloids with tunable size(such as 2,5,7,11,13,and 16 nm)and LaVO_(4)nanocrystals with well-defi ned shapes were pre-synthesized assisted with oleic acid/amine.During the following immobilization process,the particle size and shape of Au and LaVO_(4)were nearly preserved.As-prepared Au/LaVO_(4)nanocomposite showed high catalytic activity for CO oxidation at room temperature.Since sizes of gold particles were well-defi ned before the immobilization process,size effect of gold particles was easy to be investigated and the results show that 5-nm Au/LaVO_(4)nanocomposite has the highest activity for CO oxidation.This synthetic method can be extended further for the preparation of other composite nanomaterials.
基金This work was supported by the National Natural Science Foundation of China(Nos.41272224,41972231).
文摘Omphacite microstructures are important to decipher the metamorphic pressuretemperature(P-T)conditions of eclogite during subduction and exhumation processes.Here we present a systematic microstructural investigation of omphacite using transmission electron microscopy(TEM)in an ultrahigh-pressure(UHP)eclogite sample from Shuanghe,Dabie orogen,China.The omphacite can be divided into two phases:(1)Omp-1,exhibits as the main part of omphacite with P2/n space group containing small amount of dislocations and numerous antiphase domains(APDs).(2)Omp-2,shows as banded subgrains with C2/c space group containing large amount of dislocations.These two phases of omphacite have almost the same crystallography orientation and bounded by dislocation walls.Along these dislocation walls,we found some barroisite and albite microcrystals.The barroisite microcrystals contain large amount of dislocations and show a topological relation with host omphacite.While the albite microcrystals contain small amount of dislocations and does not show topological relation with host.These microstructures could give us the following metamorphic information to constrain the P-T path of eclogite:Firstly,this two omphacite space groups should be evolved from the same precursor C2/c omphacite,which had been underwent strongly plastic deformation during the syn-to late-peak metamorphic stage.Secondly,the precursor C2/c omphacite began to be retrograded and altered by small amount of barroisite microcrystals along its dislocation walls under the P-T condition of 2.2–2.6 GPa and 650–700℃ at the early amphibole eclogite stage.Thirdly,large amount of Na and other elements were exsolved from some precursor C2/c omphacite subgrains and crystallized numerous albite microcrystals at their boundaries,which is the necessary for the space group of C2/c surviving under the lower P-T conditions(1.7–1.9 GPa and 630–690 C)during the middle amphibole eclogite stage.Lastly,the rest of precursor C2/c omphacite subgrains were transformed into P2/n polymorph and formed the APDs structures under the P-T condition of^1.5 GPa and 650–680℃ during the late amphibole eclogite stage.
基金the National Natural Science Foundation of China(No.21971002)the Natural Science Foundation of Anhui Province(Nos.1908085QB45 and 2008085QB81)。
文摘High yield production of phenol from hydroxylation of benzene with low energy consumption is of paramount importance,but still challenging.Herein,a new strategy,consisting of using diatomic synergistic modulation(DSM)to effectively control the separation of photo-generated carriers for an enhanced production of phenol is reported.The atomic level dispersion of Fe and Cr respectively decorated on Al based MIL-53-NH_(2)photocatalyst(Fe1/Cr:MIL-53-NH_(2))is designed,in which Cr single atoms are substituted for Al3+while Fe single atoms are coordinated by N.Notably,the Fe1/Cr:MIL-53-NH_(2)significantly boosts the photooxidation of benzene to phenol under visible light irradiation,which is much higher than those of MIL-53-NH_(2),Cr:MIL-53-NH_(2),Fe1/MIL-53-NH_(2),and Fe nanoparticles/Cr:MIL-53-NH_(2)catalysts.Theoretical and experimental results reveal that the Cr single atoms and Fe single atoms can act as electron acceptor and electron donor,respectively,during photocatalytic reaction,exhibiting a synergistic effect on the separation of the photo-generated carriers and thereby causing great enhancement on the benzene oxidation.This strategy provides new insights for rational design of advanced photocatalysts at the atomic level.
基金the National Natural Science Foundation of China(Nos.41590623,41972231,41872230)。
文摘Intracrystalline distortions(like undulose extinction,dislocations,and subgrain boundaries)in olivine from naturally-deformed peridotites are generally taken as signs of dislocation creep.However,similar features in olivine phenocrysts that have been found in basaltic magmas are still not well understood.In particular,whether subgrain boundaries in olivine phenocrysts arise from plastic deformation or grain growth is still debated(in the latter case,they are essentially grain boundaries but not subgrain boundaries.Therefore,we used hereinafter subgrain-boundary-like structures instead of subgrain boundaries to name this kind of intracrystalline distortion).Here we carried out a detailed study on dislocations and subgrainboundary-like(SG-like)structures in olivine phenocrysts from two Hawaiian basaltic lavas by means of petrographic microscopy,scanning electron microscopy,and transmission electron microscopy(TEM).Abundant and complex dislocation substructures(free dislocations,dislocation walls,and dislocation tangles)were observed in the decorated olivine grains,similar to those in olivine from peridotite xenoliths entrained by the Hawaiian basalts.The measured average dislocation density is(2.9±1.3)×1011 m-2,and is three to five orders of magnitude higher than that in laboratory-synthesized,undeformed olivine.TEM observations on samples cut across the SG-like structures by FIB(focused ion beam)demonstrated that this kind of structures is made of an array of dislocations.These observations clearly indicate that these structures are real subgrain boundaries rather than grain boundaries.These facts suggest that the observed high dislocation densities and subgrain boundaries cannot result from crystal crystallization/growth,but can be formed by plastic deformation.These deformation features do not prove that the olivine phenocrysts(and implicitly mantle xenoliths)were deformed after their capture by the basaltic magmas,but can be ascribed to a former deformation event in a dunitic cumulate,which was formed by magmatic fractionation,then plastically deformed,and finally disaggregated and captured by the basaltic magma that brought them to the surface.
基金Supported by the National Key Research and Development Program of China(2016YFA0602100)Strategic Priority Research Program of Chinese Academy of Sciences(XDB 40000000,XDB 42000000,and XDA19060102)National Natural Science Foundation of China[42030410 and 41690122(41690120)]。
文摘In the Nino3.4 region(tropical Pacific,5°S-5°N,170°-120°W),sea surface temperature(SST)changes are highly correlated with temperature variations in the upper 40-m layer.This study explores the upper-ocean heat budget in the Nino3.4 region using Ocean Reanalysis System 5(ORAS5)monthly data from 1979 to 2018,with a focus on ocean heat transports at lateral boundaries in the top 40-m layer and their correlation with temperature variations.In the region,there is a well-defined structure of opposite meridional circulation in the upper and lower parts of the thermocline,characterized by divergence in the upper layer above 40 m and convergence in the lower layer.The change of mean temperature in the upper layer is determined by the sum of zonal,meridional,and vertical heat transports,which,however,tend to largely compensate for each other.In general,part of the surface heat flux from the atmosphere to the ocean and the heat transport from the subsurface ocean are transported out of the domain by meridional and zonal currents,leaving only a tiny part to warm or cool the upper ocean.The amplitude of the net surface heat flux effective for the entire 40-m layer of the ocean is weaker than the lateral heat transport.On an interannual timescale,variations of heat transports in both zonal and meridional are positively correlated with temperature anomalies,while the vertical heat transport from the subsurface ocean is negatively correlated.Composite analyses for five El Nino events and five La Nina events also revealed that there is a positive contribution of horizontal transport convergence to temperature anomalies during the evolution of El Nino(warming)and La Nina(cooling),while vertical transport acts against temperature variations.
基金Supported by the National Key Research and Development Program of China(2018YFC1505906)National Natural Science Foundation of China(41905067 and 41775066)+1 种基金National(Key)Basic Research and Development(973)Program of China(2015CB453203)UK–China Research and Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund。
文摘Based on the empirical orthogonal function(EOF) analysis, the East Asia–Pacific(EAP) teleconnection is extracted as the leading mode of the subseasonal variability over East Asia in summer, with a meridional tripole structure and significant periods of 10–30 and 50–70 days. A two-dimensional phase–space diagram is established for the EAP index and its time tendency so as to monitor the real-time state of EAP events. Based on the phase composite analysis, the general circulation anomalies first occur over the high-latitude area of Europe centered near Novaya Zemlya at the beginning of EAP events. These general circulation anomalies then influence rainfall over Northeast China,North China, and the region south of the Yangtze River valley(YRV) as the phases of EAP event progress. The representation, predictability, and prediction skill of the EAP teleconnection are examined in the two fully coupled subseasonal prediction systems of the Beijing Climate Center(BCC) and UK Met Office(UKMO GloSea5). Both models are able to simulate the EAP meridional tripole over East Asia as the leading mode and its characteristics of evolution as well, except for the weaker precursors over Novaya Zemlya and an inconspicuous influence on precipitation over Northeast China. The actual prediction skill of the EAP teleconnection during May–September(MJJAS) is about 10 days in the BCC model and 15 days in the UKMO model based on correlation measures, but is higher when initialized from the EAP peak phases or when targeted on strong EAP scenarios. However, both of the ensemble prediction systems are under-dispersive and the predictable signals extend to 18 and 30 days in BCC and UKMO models based on signal-to-error metrics, indicating that there may be further scope for enhancing the capability of these models for the EAP teleconnection prediction and the associated impacts studies.
