Ny-Ålesund,located in Arctic Svalbard,is one of the most sensitive areas on Earth to global warming.In recent years,accelerated glacier ablation has become remarkable in Ny-Ålesund.Glacial meltwaters dischar...Ny-Ålesund,located in Arctic Svalbard,is one of the most sensitive areas on Earth to global warming.In recent years,accelerated glacier ablation has become remarkable in Ny-Ålesund.Glacial meltwaters discharge a substantial quantity of materials to the ocean,affecting downstream ecosystems and adjacent oceans.In August 2015,various water samples were taken near Ny-Ålesund,including ice marginal meltwater,proglacial meltwater,supraglacial meltwater,englacial meltwater,and groundwater.Trace metals(Al,Cr,Mn,Fe,Co,Cu,Zn,Cd,and Pb),major ions,alkalinity,pH,dissolved oxygen,water temperature and electric conductivity were also measured.Major ions were mainly controlled by chemical weathering intensity and reaction types,while trace metals were influenced by both chemical weathering and physicochemical control upon their mobility.Indeed,we found that Brøggerbreen was dominated by carbonate weathering via carbonation of carbonate,while Austre Lovénbreen and Pedersenbreen were dominated by sulfide oxidation coupled with carbonate dissolution with a doubled silicate weathering.The higher enrichment of trace metals in supraglacial meltwater compared to ice marginal and proglacial meltwater suggested anthropogenic pollution from atmospheric deposition.In ice marginal and proglacial meltwater,principal component analysis indicated that trace metals like Cr,Al,Co,Mn and Cd were correlated to chemical weathering.This implies that under accelerated glacier retreat,glacier-derived chemical components are subjected to future changes in weathering types and intensity.展开更多
Antarctic coastal polynyas are biological hotspots in the Southern Ocean that support the abundance of hightrophic-level predators and are important for carbon cycling in the high-latitude oceans.In this study,we exam...Antarctic coastal polynyas are biological hotspots in the Southern Ocean that support the abundance of hightrophic-level predators and are important for carbon cycling in the high-latitude oceans.In this study,we examined the interannual variation of summertime phytoplankton biomass in the Marguerite Bay polynya(MBP)in the western Antarctic Peninsula area,and linked such variability to the Southern Annular Mode(SAM)that dominated the southern hemisphere extratropical climate variability.Combining satellite data,atmosphere reanalysis products and numerical simulations,we found that the interannual variation of summer chlorophyll-a(Chl-a)concentration in the MBP is significantly and negatively correlated with the spring SAM index,and weakly correlated with the summer SAM index.The negative relation between summer Chl-a and spring SAM is due to weaker spring vertical mixing under a more positive SAM condition,which would inhibit the supply of iron from deep layers into the surface euphotic layer.The negative relation between spring mixing and spring SAM results from greater precipitation rate over the MBP region in positive SAM phase,which leads to lower salinity in the ocean surface layer.The coupled physical-biological mechanisms between SAM and phytoplankton biomass revealed in this study is important for us to predict the future variations of phytoplankton biomasses in Antarctic polynyas under climate change.展开更多
The oceanic trace metals iron(Fe),nickel(Ni),copper(Cu),zinc(Zn),and cadmium(Cd)are crucial to marine phytoplankton growth and global carbon cycle,and the analysis of their stable isotopes can provide valuable insight...The oceanic trace metals iron(Fe),nickel(Ni),copper(Cu),zinc(Zn),and cadmium(Cd)are crucial to marine phytoplankton growth and global carbon cycle,and the analysis of their stable isotopes can provide valuable insights into their biogeochemical cycles within the ocean.However,the simultaneous isotopic analysis of multiple elements present in seawater is challenging because of their low concentrations,limited volumes of the test samples,and high salt matrix.In this study,we present the novel method developed for the simultaneous analysis of five isotope systems by 1 L seawater sample.In the developed method,the NOBIAS Chelate-PA1 resin was used to extract metals from seawater,the AG MP-1M anion-exchange resin to purify Cu,Fe,Zn,Cd,and the NOBIAS Chelate-PA1 resin to further extract Ni from the matrix elements.Finally,a multi-collector inductively coupled plasma mass spectroscope(MC-ICPMS)was employed for the isotopic measurements using a doublespike technique or sample-standard bracketing combined with internal normalization.This method exhibited low total procedural blanks(0.04 pg,0.04 pg,0.21 pg,0.15 pg,and 3 pg for Ni,Cu,Fe,Zn,and Cd,respectively)and high extraction efficiencies(100.5%±0.3%,100.2%±0.5%,97.8%±1.4%,99.9%±0.8%,and 100.1%±0.2%for Ni,Cu,Fe,Zn,and Cd,respectively).The external errors and external precisions of this method could be considered negligible.The proposed method was further tested on the seawater samples obtained from the whole vertical profile of a water column during the Chinese GEOTRACES GP09 cruise in the Northwest Pacific,and the results showed good agreement with previous related data.This innovative method will contribute to the advancement of isotope research and enhance our understanding of the marine biogeochemical cycling of Fe,Ni,Cu,Zn,and Cd.展开更多
Objective:To investigate the relationship between coronavirus disease 2019(COVID-19)and non-specific interstitial pneumonia(NSIP),with a focus on the clinical features of COVID-19 and NSIP,and the key points of differ...Objective:To investigate the relationship between coronavirus disease 2019(COVID-19)and non-specific interstitial pneumonia(NSIP),with a focus on the clinical features of COVID-19 and NSIP,and the key points of differential diagnosis.Methods:The clinical data of 20 patients with common-type COVID-19 and NSIP admitted to Linyi People’s Hospital from January 21,2020,to June 21,2022,were retrospectively analyzed.Gender,age,history of residence in Hubei province,underlying diseases,clinical manifestations,laboratory test results(including blood routine indexes,inflammatory markers,liver function indexes,and coagulation indexes),and computed tomography(CT)scan images were compared between the two groups.Results:COVID-19 patients were younger than NSIP patients(P<0.05).Nine COVID-19 patients had a travel history to Hubei province,while none of the NSIP patients did(P<0.05).Eight COVID-19 patients had underlying chronic conditions,fewer than the NSIP group(12 patients;P<0.05).Both groups experienced symptoms such as shortness of breath,expectoration,fatigue,and runny nose,but fever and cough were more severe and more frequent in the COVID-19 group.Compared to normal reference ranges,both groups exhibited normal white blood cell counts(WBC)and liver function indexes,but elevated lymphocyte counts(LYMP),inflammatory markers,and coagulation indexes,with reduced neutrophil counts(NE).WBC and LYMP were higher in the COVID-19 group compared to the NSIP group.Male patients in the COVID-19 group had higher erythrocyte sedimentation rates and C-reactive protein values than those in the NSIP group,while procalcitonin levels were lower in the COVID-19 group,although the differences were not statistically significant(all P>0.05).The NE count in the COVID-19 group was significantly lower than in the NSIP group(P<0.05).Alanine aminotransferase,total bilirubin,and indirect bilirubin were significantly higher in the COVID-19 group compared to the NSIP group(P<0.05).Chest CT scans of both groups showed bilateral patchy ground-glass opacities,but the lesions in COVID-19 patients were scattered.NSIP patients’chest CTs showed diffuse lesions centered around the hilum or multiple lesions in both lungs,with pleural involvement being rare.Conclusion:While there are certain specific clinical,laboratory,and imaging findings in both COVID-19 and NSIP,the specificity of these features is not high.Differentiating the two requires careful consideration of epidemiological history,nucleic acid testing,and antigen-antibody levels.展开更多
A thorough understanding of the biogeochemical cycling of trace metals in the ocean is crucial because of the important role these elements play in regulating metabolism in marine biotas and thus,the climate.However,a...A thorough understanding of the biogeochemical cycling of trace metals in the ocean is crucial because of the important role these elements play in regulating metabolism in marine biotas and thus,the climate.However,a precise and accurate analysis of trace metals in seawater is difficult because they are present at extremely low concentrations in a high salt matrix.In this study,we report an analytical method for the preconcentration and separation of six trace metals,Fe,Ni,Cu,Zn,Cd and Pb,in seawater using a sea FAST automatic solid-phase extraction device,analysis by a triple quadrupole collision/reaction technique with inductively coupled plasma mass spectrometry(ICP-MS),and quantification by the isotope dilution technique.A small volume(10 m L)of seawater sample was mixed with a multi-element isotope spike and subjected to sea FAST procedures.The preconcentrate solution was then analyzed using the optimized collision/reaction cell mode of ICP-MS,with NH_(3)gas for Fe and Cd with a flow rate of 0.22 m L/min and He for Ni,Cu,Zn and Pb with a flow rate of 4.0 m L/min.The procedure blanks were 130 pmol/L,3.0 pmol/L,6.8 pmol/L,37 pmol/L,0.29 pmol/L and 0.42 pmol/L,for Fe,Ni,Cu,Zn,Cd and Pb,respectively.The method was validated using five reference materials(SLRs-6,SLEW-3,CASS-6,NASS-7 and GEOTRACE-GSC),and our results were consistent with the consensus values.The method was further validated by measuring full-water-column seawater samples from the subtropical Northwest Pacific Ocean,and our results demonstrated good oceanic consistency.展开更多
In this study,the tomography of dynamic stress coefficient(TDSC)was established based on a mechanical model of stress wave propagation in bedding planes and a mathematical model of the stress wave attenuation in rock ...In this study,the tomography of dynamic stress coefficient(TDSC)was established based on a mechanical model of stress wave propagation in bedding planes and a mathematical model of the stress wave attenuation in rock masses.The reliability of the TDSC was verified by a linear bedding plane model and field monitoring.Generally,the TDSC in the dynamic stress propagation of bedding planes increases with the following conditions:(1)the increase of the normal stiffness of the bedding plane,(2)the increase of the incident angle of the stress wave,(3)the decrease of the incident frequency of the stress wave,or(4)the growth of three ratios(the ratios of rock densities,elastic moduli,and the Poisson’s ratios)of rocks on either side of bedding planes.The additional stress weakens TDSC linearly and slowly during the stress wave propagation in bedding planes,and the weakening effect increases with the growth of the three ratios.Besides,the TDSC decreases exponentially in the rock mass as propagation distance increases.In a field case,the TDSC decreases significantly as vertical and horizontal distances increase and its wave range increases as vertical distance increases in the sedimentary rock layers.展开更多
To develop biodegradable magnesium alloy with desirable corrosion properties,a low Gd-containing Mg-3Gd-1Zn-0.4Zr(wt%,GZ31K)alloy was prepared.The as-cast ingot was solution treated and then hot extruded.Microstructur...To develop biodegradable magnesium alloy with desirable corrosion properties,a low Gd-containing Mg-3Gd-1Zn-0.4Zr(wt%,GZ31K)alloy was prepared.The as-cast ingot was solution treated and then hot extruded.Microstructures were characterized by scanning electron microscopy(SEM).Corrosion behavior of the alloy under each condition was studied by hydrogen evolution and quasi in-situ corrosion methods.It has been found that the as-cast alloy is composed ofα-Mg,stacking faults(SFs)at the outer edge of the matrix grains,and eutectic phase along the grain boundaries.After solution treatment,the SFs disappear and precipitates rich in Zn and Zr elements form in the grain interior and boundaries.The microstructure is significantly refined after extrusion.Hydrogen evolution tests show that the as-cast alloy exhibits the best corrosion resistance,and the solution-treated alloy has the worst corrosion resistance.Corrosion rate of the alloy under each condition decreases first and then increases with prolonging immersion time.Corrosion experiments demonstrate thatα-Mg was corroded preferentially,the eutectic phase and precipitates exhibit better corrosion resistance.The as-extruded alloy demonstrates uniform corrosion due to fine and homogeneous microstructure.展开更多
Graphene oxide （GO） contains numerous functional groups that facilitate the intercalation of polar solvents. The properties and applications of GO are closely related to its interlayer spacing. We report on the chan...Graphene oxide （GO） contains numerous functional groups that facilitate the intercalation of polar solvents. The properties and applications of GO are closely related to its interlayer spacing. We report on the changes in the interlayer spacing of GO after the adsorption of water molecules and the polar organic solvents C2H602 （EG）, C3HTNO （DMF）, C5H9NO （NMP）. Experiments were conducted to investigate the variations in the functional groups and structure of GO after solvent adsorp-tion, and they play a vital role in modeling and verifying the results of molecular dynamics simulation. The most stable GO structures are obtained through molecular dynamics simulation. The expansion of the interlayer spacing of GO after the adsorption of monolayer solvent molecules corresponds to the minimum three-dimensional size of the solvent molecules. The spatial arrangement of solvent molecules also contributes to the changes in interlayer spacing. Most adsorbed molecules are oriented parallel to the carbon plane of GO. However, as additional molecules are adsorbed into the interlaminations of GO, the adsorbed molecules are oriented perpendicular to the carbon plane of GO, and a large space forms between two GO interlayers. In addition, the role of large molecules in increasing interlayer spacing becomes more crucial than that of water molecules in the adsorption of binary solvent systems by GO.展开更多
A revision of the genus Chrysotus Meigen from Sichuan,China is presented.Sixteen species are recorded.One species is described as new to science:Chrysotus shuensis Liu&Yang sp.nov.
Let(X,φ) be a nonautonomous dynamical system.In this paper,we introduce the notions of packing topological entropy and measure-theoretical upper entropy for nonautonomous dynamical systems.Moreover,we establish the v...Let(X,φ) be a nonautonomous dynamical system.In this paper,we introduce the notions of packing topological entropy and measure-theoretical upper entropy for nonautonomous dynamical systems.Moreover,we establish the variational principle between the packing topological entropy and the measure-theoretical upper entropy.展开更多
Diamond, cubic boron nitride(c-BN), silicon(Si), and germanium(Ge), as examples of typical strong covalent materials, have been extensively investigated in recent decades, owing to their fundamental importance in mate...Diamond, cubic boron nitride(c-BN), silicon(Si), and germanium(Ge), as examples of typical strong covalent materials, have been extensively investigated in recent decades, owing to their fundamental importance in material science and industry. However, an in-depth analysis of the character of these materials' mechanical behaviors under harsh service environments, such as high pressure, has yet to be conducted. Based on several mechanical criteria, the effect of pressure on the mechanical properties of these materials is comprehensively investigated.It is demonstrated that, with respect to their intrinsic brittleness/ductile nature, all these materials exhibit ubiquitous pressure-enhanced ductility. By analyzing the strength variation under uniform deformation, together with the corresponding electronic structures, we reveal for the first time that the pressure-induced mechanical softening/weakening exhibits distinct characteristics between diamond and c-BN, owing to the differences in their abnormal charge-depletion evolution under applied strain, whereas a monotonous weakening phenomenon is observed in Si and Ge. Further investigation into dislocation-mediated plastic resistance indicates that the pressure-induced shuffle-set plane softening in diamond(c-BN), and weakening in Si(Ge), can be attributed to the reduction of antibonding states below the Fermi level, and an enhanced metallization, corresponding to the weakening of the bonds around the slipped plane with increasing pressure, respectively. These findings not only reveal the physical mechanism of pressure-induced softening/weakening in covalent materials, but also highlights the necessity of exploring strain-tunable electronic structures to emphasize the mechanical response in such covalent materials.展开更多
Platycladi Cacumen(Platycladus orientalis leaf)is a traditional Chinese medicine with a variety of medicinal values,and its efficacy has been recorded by many ancient books.Its chemical components mainly include flavo...Platycladi Cacumen(Platycladus orientalis leaf)is a traditional Chinese medicine with a variety of medicinal values,and its efficacy has been recorded by many ancient books.Its chemical components mainly include flavonoids,volatile oil,tannins and so on.Pharmacological studies have confirmed that P.orientalis leaves have various pharmacological effects such as antibacterial,anti-oxidant,anti-tumor,hair growth promoting and hemostatic effects.Through review of the research on the chemical components and pharmacological effects of P.orientalis leaves,this study is intended to provide reference for the research,development and utilization of P.orientalis.展开更多
Many works have been made for predicting the failure of composite joints.However,there is still lack of method for multi-bolted composite joints subjected to the hygrothermal environment.In this work,a characteristic ...Many works have been made for predicting the failure of composite joints.However,there is still lack of method for multi-bolted composite joints subjected to the hygrothermal environment.In this work,a characteristic curve-based numerical framework is proposed,which includes two main steps and shows low computational cost.Firstly,a 3D finite element model considering hygrothermal effects is established to analyze the bolt-load distribution of multi-bolted joints.Secondly,a new characteristic curve considering the hygrothermal influence is used to obtain the failure pattern and strength of composite joints.The two-,three-and four-bolted composite joints with-55℃/dry(CTD),23℃/dry(RTD)and 70℃/wet(ETW)conditions are investigated.The test outcomes present good agreement with predicted results,which illustrates the effectiveness and applicability of the proposed method.Meanwhile,it is shown that the environmental condition affects the bolt-load ratio slightly,but does not change the location of the key loaded hole.Furthermore,deviations of the strengths in CTD and ETW conditions are about 5%and-16%from that in the RTD condition,respectively.The environmental condition does not affect the failure modes of two-and three-bolted joints,whereas changes the failure mode of the four-bolted joint.The proposed method is efficient,reliable and needs only linear elastic FE analysis,making it applicable for engineering practice.展开更多
Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection often leads to pulmonary complications.Cardiovascular sequelae,including myocarditis and heart failure,have also been reported.Here,the study presen...Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection often leads to pulmonary complications.Cardiovascular sequelae,including myocarditis and heart failure,have also been reported.Here,the study presents two fulminant myocarditis cases infected by SARS-CoV-2 exhibiting remarkable elevation of cardiac biomarkers without significant pulmonary injury,as determined by imaging examinations.Immunohistochemical staining reveals the viral antigen within cardiomyocytes,indicating that SARSCoV-2 could directly infect the myocardium.The full viral genomes from respiratory,anal,and myocardial specimens are obtained via next-generation sequencing.Phylogenetic analyses of the whole genome and spike gene indicate that viruses in the myocardium/pericardial effusion and anal swabs are closely related and cluster together yet diverge from those in the respiratory samples.In addition,unique mutations are found in the anal/myocardial strains compared to the respiratory strains,suggesting tissue-specific virus mutation and adaptation.These findings indicate genetically distinct SARS-CoV-2 variants have infiltrated and disseminated within myocardial tissues,independent of pulmonary injury,and point to different infection routes between the myocardium and respiratory tract,with myocardial infections potentially arising from intestinal infection.These findings highlight the potential for systemic SARS-CoV-2 infection and the importance of a thorough multi-organ assessment in patients for a comprehensive understanding of thepathogenesisof COVID-19.展开更多
Metal-organic framework[MOF,i.e.,NH_(2)-MIL-53(Al)]modified TiO_(2)(NMT)composite photoanodes were successfully prepared by hydrothermal synthesis and were used for the photoelectrochemical cathodic protection(PECCP)o...Metal-organic framework[MOF,i.e.,NH_(2)-MIL-53(Al)]modified TiO_(2)(NMT)composite photoanodes were successfully prepared by hydrothermal synthesis and were used for the photoelectrochemical cathodic protection(PECCP)of nickel-plated magnesium alloy(Mg/Ni).Results showed that the synthesis tem-perature significantly impacted the morphology and PECCP performance of the NMT photoanodes.The NMT@150 photoanode prepared at a reaction temperature of 150℃exhibited the best PECCP perfor-mance and produced a current density of 1980μA cm^(-2)under visible light irradiation,which was 19.8 times higher than that of a single TiO_(2)photoanode.The composite photoanode could polarize the open circuit potential of the coupled Mg/Ni electrode to-876 mV and remain relatively stable within 35 h.XPS and EPR tests showed that a Z-scheme heterojunction was formed between the NH_(2)-MIL-53(Al)and TiO_(2)nanotubes,allowing the photogenerated electrons to accumulate mainly on the conduction band of NH_(2)-MIL-53(Al).The heterojunction greatly promoted the separation and transfer of photogenerated electron-hole in the NMT composite photoanode,significantly enhancing the PECCP performance for Mg/Ni.展开更多
Organic-inorganic hybrid perovskite formamidinium lead bromide nanosheet(FAPb Br_(3)NS)is regarded as a superior substance used to construct optoelectronic devices.However,its uncontrollable stability seriously affect...Organic-inorganic hybrid perovskite formamidinium lead bromide nanosheet(FAPb Br_(3)NS)is regarded as a superior substance used to construct optoelectronic devices.However,its uncontrollable stability seriously affects its application in the field of photodetectors.In this paper,FAPb Br_(3)is combined with cadmium sulfide nanobelt(Cd S NB)to construct a hybrid device that greatly improves the stability and performance of the photodetector.The response of the FAPb Br_(3)NS/Cd S NB detector under 490 nm light illumination reaches 5712 A/W,while the response of the FAPb Br_(3)photodetector under equivalent conditions is only 25.45 A/W.The photocurrent of the FAPb Br_(3)NS/Cd S NB photodetector is nearly 80.25%of the initial device after exposure to air for 60 days.The difference in electric field distribution between the single material device and the composite device is simulated by the finite-difference time-domain method.It shows the advantages of composite devices in photoconductive gain and directly promotes the hybrid device performance.This paper presents a new possibility for high stability,fast response photodetectors.展开更多
To effectively obtain the downforce of the gauge wheels in real time,mechanical models of the interaction among the ground,gauge wheels,gauge wheel arms,and depth adjustment lever were constructed.A measuring method w...To effectively obtain the downforce of the gauge wheels in real time,mechanical models of the interaction among the ground,gauge wheels,gauge wheel arms,and depth adjustment lever were constructed.A measuring method was proposed for monitoring the downforce through a two-dimensional radial sensing device,and a corresponding prototype was designed.Through simulation analysis of the sensing device with ANSYS,a 45°angle was determined to exist between the strain gauge axis and the sensing device axis,and the Wheatstone bridging circuit of R1+R3−R5−R7(R stands for resistance strain gauge,different figures represent the strain gauge number)and R2+R4−R6−R8 was adopted.According to performance and calibration tests for the sensing device,the maximum interaction effect between the X and Y axes was 2.52%,and the output signal was stable and consistent.The standard error of the slope of the fitting equation of the downforce calculation model is 0.008.According to the field test,the average downforce of the gauge wheels was 1148,1017,843,and 713 N,at different sowing speeds of 6,8,10,and 12 km/h,respectively.The coefficients of variation were 0.40,0.41,0.62,and 0.71,respectively.The results indicate that the downforce fluctuation of the gauge wheels became more severe with increasing planting speed.Both the strain simulation analysis and field test verified that the measurement method is accurate and reliable,the performance of the sensing device is stable,the measurement method and sensing device meet the application requirements and lay a foundation for the research of accurate and stable control of downforce of no-till planter.展开更多
Background Sawtooth wave buncher is widely used in low-energy ion injection at cyclotron accelerators.Its performance significantly impacts on the intensity of ion beam delivered to experimental terminals.In order to ...Background Sawtooth wave buncher is widely used in low-energy ion injection at cyclotron accelerators.Its performance significantly impacts on the intensity of ion beam delivered to experimental terminals.In order to meet the high-intensity requirement of physical experiments,we upgrade the existing B02 buncher in the axial injection line of the SFC with the dual-model sawtooth wave buncher for low-energy ion injection.Methods We use a three harmonics synthesis method in the dual-sawtooth wave buncher.First,we use three harmonics to generate a low-level sawtooth wave.Second,the low-level wave is amplified by a broadband amplifier to generate high voltage at a single-gap electrode.Third,the electrode is matched to the amplifier by a 1:9 transmission line transformer.Results The new buncher has been installed online since September 2022.Our tested results show that the buncher is capable of being operated at the full-frequency mode and half-frequency mode with the corresponding frequency ranging from 2.75 to 8.0 MHz and 5.5 to 16.0 MHz,respectively.The effective voltage can be up to 2.54 kV and 1.6 kV,respectively.Also,the sawtooth wave buncher works reliably,and a 4.5-8.6 times gain in the beam intensity is achieved.Conclusion By using the three-harmonic synthesis method,a new dual-mode high-voltage sawtooth wave buncher has been built.This sawtooth wave buncher has succeeded in being applied with the high buncher voltage over a wide frequency range with good reliability and stability.This newly-built sawtooth wave buncher significantly increases the ion beam current for low-energy ion injection at the HIRFL-SFC cyclotron.展开更多
基金The National Natural Science Foundation of China under contract Nos 42076227,41676175 and 41276202the Chinese Arctic and Antarctic Administration under contract No.CHINARE-YRS2015-21+1 种基金the Shanghai Pilot Program for Basic Re-search-Shanghai Jiao Tong University under contract No.21TQ1400201the Shanghai Frontiers Science Center of Polar Science(SCOPS).
文摘Ny-Ålesund,located in Arctic Svalbard,is one of the most sensitive areas on Earth to global warming.In recent years,accelerated glacier ablation has become remarkable in Ny-Ålesund.Glacial meltwaters discharge a substantial quantity of materials to the ocean,affecting downstream ecosystems and adjacent oceans.In August 2015,various water samples were taken near Ny-Ålesund,including ice marginal meltwater,proglacial meltwater,supraglacial meltwater,englacial meltwater,and groundwater.Trace metals(Al,Cr,Mn,Fe,Co,Cu,Zn,Cd,and Pb),major ions,alkalinity,pH,dissolved oxygen,water temperature and electric conductivity were also measured.Major ions were mainly controlled by chemical weathering intensity and reaction types,while trace metals were influenced by both chemical weathering and physicochemical control upon their mobility.Indeed,we found that Brøggerbreen was dominated by carbonate weathering via carbonation of carbonate,while Austre Lovénbreen and Pedersenbreen were dominated by sulfide oxidation coupled with carbonate dissolution with a doubled silicate weathering.The higher enrichment of trace metals in supraglacial meltwater compared to ice marginal and proglacial meltwater suggested anthropogenic pollution from atmospheric deposition.In ice marginal and proglacial meltwater,principal component analysis indicated that trace metals like Cr,Al,Co,Mn and Cd were correlated to chemical weathering.This implies that under accelerated glacier retreat,glacier-derived chemical components are subjected to future changes in weathering types and intensity.
基金The Key Research&Development Program of the Ministry of Science and Technology of China under contract No.2022YFC2807601the National Natural Science Foundation of China under contract Nos 41941008 and 41876221+3 种基金the Fund of Shanghai Science and Technology Committee under contract Nos 20230711100 and 21QA1404300the Impact and Response of Antarctic Seas to Climate Change funded by the Chinese Arctic and Antarctic Administration under contract No.IRASCC 1-02-01Bthe National Key Research and Development Program of China under contract No.2019YFC1509102the Shanghai Pilot Program for Basic Research—Shanghai Jiao Tong University under contract No.21TQ1400201。
文摘Antarctic coastal polynyas are biological hotspots in the Southern Ocean that support the abundance of hightrophic-level predators and are important for carbon cycling in the high-latitude oceans.In this study,we examined the interannual variation of summertime phytoplankton biomass in the Marguerite Bay polynya(MBP)in the western Antarctic Peninsula area,and linked such variability to the Southern Annular Mode(SAM)that dominated the southern hemisphere extratropical climate variability.Combining satellite data,atmosphere reanalysis products and numerical simulations,we found that the interannual variation of summer chlorophyll-a(Chl-a)concentration in the MBP is significantly and negatively correlated with the spring SAM index,and weakly correlated with the summer SAM index.The negative relation between summer Chl-a and spring SAM is due to weaker spring vertical mixing under a more positive SAM condition,which would inhibit the supply of iron from deep layers into the surface euphotic layer.The negative relation between spring mixing and spring SAM results from greater precipitation rate over the MBP region in positive SAM phase,which leads to lower salinity in the ocean surface layer.The coupled physical-biological mechanisms between SAM and phytoplankton biomass revealed in this study is important for us to predict the future variations of phytoplankton biomasses in Antarctic polynyas under climate change.
基金The National Key Research and Development Program of China under contract No.2022YFE0136500the National Nature Science Foundation of China under contract Nos 41890801 and 42076227the Shanghai Pilot Program for Basic Research-Shanghai Jiao Tong University under contract No.21TQ1400201.
文摘The oceanic trace metals iron(Fe),nickel(Ni),copper(Cu),zinc(Zn),and cadmium(Cd)are crucial to marine phytoplankton growth and global carbon cycle,and the analysis of their stable isotopes can provide valuable insights into their biogeochemical cycles within the ocean.However,the simultaneous isotopic analysis of multiple elements present in seawater is challenging because of their low concentrations,limited volumes of the test samples,and high salt matrix.In this study,we present the novel method developed for the simultaneous analysis of five isotope systems by 1 L seawater sample.In the developed method,the NOBIAS Chelate-PA1 resin was used to extract metals from seawater,the AG MP-1M anion-exchange resin to purify Cu,Fe,Zn,Cd,and the NOBIAS Chelate-PA1 resin to further extract Ni from the matrix elements.Finally,a multi-collector inductively coupled plasma mass spectroscope(MC-ICPMS)was employed for the isotopic measurements using a doublespike technique or sample-standard bracketing combined with internal normalization.This method exhibited low total procedural blanks(0.04 pg,0.04 pg,0.21 pg,0.15 pg,and 3 pg for Ni,Cu,Fe,Zn,and Cd,respectively)and high extraction efficiencies(100.5%±0.3%,100.2%±0.5%,97.8%±1.4%,99.9%±0.8%,and 100.1%±0.2%for Ni,Cu,Fe,Zn,and Cd,respectively).The external errors and external precisions of this method could be considered negligible.The proposed method was further tested on the seawater samples obtained from the whole vertical profile of a water column during the Chinese GEOTRACES GP09 cruise in the Northwest Pacific,and the results showed good agreement with previous related data.This innovative method will contribute to the advancement of isotope research and enhance our understanding of the marine biogeochemical cycling of Fe,Ni,Cu,Zn,and Cd.
基金Linyi Key Research and Development Program(Medical)(Project No.2023YX0137)General Research Project of Linyi Science and Technology Association(Project No.2024kxy109)。
文摘Objective:To investigate the relationship between coronavirus disease 2019(COVID-19)and non-specific interstitial pneumonia(NSIP),with a focus on the clinical features of COVID-19 and NSIP,and the key points of differential diagnosis.Methods:The clinical data of 20 patients with common-type COVID-19 and NSIP admitted to Linyi People’s Hospital from January 21,2020,to June 21,2022,were retrospectively analyzed.Gender,age,history of residence in Hubei province,underlying diseases,clinical manifestations,laboratory test results(including blood routine indexes,inflammatory markers,liver function indexes,and coagulation indexes),and computed tomography(CT)scan images were compared between the two groups.Results:COVID-19 patients were younger than NSIP patients(P<0.05).Nine COVID-19 patients had a travel history to Hubei province,while none of the NSIP patients did(P<0.05).Eight COVID-19 patients had underlying chronic conditions,fewer than the NSIP group(12 patients;P<0.05).Both groups experienced symptoms such as shortness of breath,expectoration,fatigue,and runny nose,but fever and cough were more severe and more frequent in the COVID-19 group.Compared to normal reference ranges,both groups exhibited normal white blood cell counts(WBC)and liver function indexes,but elevated lymphocyte counts(LYMP),inflammatory markers,and coagulation indexes,with reduced neutrophil counts(NE).WBC and LYMP were higher in the COVID-19 group compared to the NSIP group.Male patients in the COVID-19 group had higher erythrocyte sedimentation rates and C-reactive protein values than those in the NSIP group,while procalcitonin levels were lower in the COVID-19 group,although the differences were not statistically significant(all P>0.05).The NE count in the COVID-19 group was significantly lower than in the NSIP group(P<0.05).Alanine aminotransferase,total bilirubin,and indirect bilirubin were significantly higher in the COVID-19 group compared to the NSIP group(P<0.05).Chest CT scans of both groups showed bilateral patchy ground-glass opacities,but the lesions in COVID-19 patients were scattered.NSIP patients’chest CTs showed diffuse lesions centered around the hilum or multiple lesions in both lungs,with pleural involvement being rare.Conclusion:While there are certain specific clinical,laboratory,and imaging findings in both COVID-19 and NSIP,the specificity of these features is not high.Differentiating the two requires careful consideration of epidemiological history,nucleic acid testing,and antigen-antibody levels.
基金The National Natural Science Foundation of China under contract Nos 41921006,41890801 and 42076227the Impact and Response of Antarctic Seas to Climate Change,Grant 583 under contract No.IRASCC 1-02-01B。
文摘A thorough understanding of the biogeochemical cycling of trace metals in the ocean is crucial because of the important role these elements play in regulating metabolism in marine biotas and thus,the climate.However,a precise and accurate analysis of trace metals in seawater is difficult because they are present at extremely low concentrations in a high salt matrix.In this study,we report an analytical method for the preconcentration and separation of six trace metals,Fe,Ni,Cu,Zn,Cd and Pb,in seawater using a sea FAST automatic solid-phase extraction device,analysis by a triple quadrupole collision/reaction technique with inductively coupled plasma mass spectrometry(ICP-MS),and quantification by the isotope dilution technique.A small volume(10 m L)of seawater sample was mixed with a multi-element isotope spike and subjected to sea FAST procedures.The preconcentrate solution was then analyzed using the optimized collision/reaction cell mode of ICP-MS,with NH_(3)gas for Fe and Cd with a flow rate of 0.22 m L/min and He for Ni,Cu,Zn and Pb with a flow rate of 4.0 m L/min.The procedure blanks were 130 pmol/L,3.0 pmol/L,6.8 pmol/L,37 pmol/L,0.29 pmol/L and 0.42 pmol/L,for Fe,Ni,Cu,Zn,Cd and Pb,respectively.The method was validated using five reference materials(SLRs-6,SLEW-3,CASS-6,NASS-7 and GEOTRACE-GSC),and our results were consistent with the consensus values.The method was further validated by measuring full-water-column seawater samples from the subtropical Northwest Pacific Ocean,and our results demonstrated good oceanic consistency.
基金This work is supported by the National Natural Science Foundation of China(Nos.51804099 and U1704129)the Focus Research and Special Development for Scientific and Technological Project of Henan Province(No.202102310542)+1 种基金the Fundamental Research Funds for the Central Universities(No.2018ZDPY02ZDPY02)the research fund of State Key Laboratory of Coal Resources and Safe Mining,CUMT(SKLCRSM19KF011).
文摘In this study,the tomography of dynamic stress coefficient(TDSC)was established based on a mechanical model of stress wave propagation in bedding planes and a mathematical model of the stress wave attenuation in rock masses.The reliability of the TDSC was verified by a linear bedding plane model and field monitoring.Generally,the TDSC in the dynamic stress propagation of bedding planes increases with the following conditions:(1)the increase of the normal stiffness of the bedding plane,(2)the increase of the incident angle of the stress wave,(3)the decrease of the incident frequency of the stress wave,or(4)the growth of three ratios(the ratios of rock densities,elastic moduli,and the Poisson’s ratios)of rocks on either side of bedding planes.The additional stress weakens TDSC linearly and slowly during the stress wave propagation in bedding planes,and the weakening effect increases with the growth of the three ratios.Besides,the TDSC decreases exponentially in the rock mass as propagation distance increases.In a field case,the TDSC decreases significantly as vertical and horizontal distances increase and its wave range increases as vertical distance increases in the sedimentary rock layers.
基金This project was supported by the Natural Science Foundation of Jiangsu Province for Outstanding Youth(BK20160081)the Natural Science Foundation of Higher Education Institutions of Jiangsu Province-Key Project(18KJA430008)+2 种基金the Jiangsu Government Scholarship for Overseas Studies,the“333 Project”of Jiangsu Province(BRA2018338)the National Natural Science Foundation of China(51701093)the Outstanding Scientific and Technological Innovation Team in Colleges and Universities of Jiangsu Province.
文摘To develop biodegradable magnesium alloy with desirable corrosion properties,a low Gd-containing Mg-3Gd-1Zn-0.4Zr(wt%,GZ31K)alloy was prepared.The as-cast ingot was solution treated and then hot extruded.Microstructures were characterized by scanning electron microscopy(SEM).Corrosion behavior of the alloy under each condition was studied by hydrogen evolution and quasi in-situ corrosion methods.It has been found that the as-cast alloy is composed ofα-Mg,stacking faults(SFs)at the outer edge of the matrix grains,and eutectic phase along the grain boundaries.After solution treatment,the SFs disappear and precipitates rich in Zn and Zr elements form in the grain interior and boundaries.The microstructure is significantly refined after extrusion.Hydrogen evolution tests show that the as-cast alloy exhibits the best corrosion resistance,and the solution-treated alloy has the worst corrosion resistance.Corrosion rate of the alloy under each condition decreases first and then increases with prolonging immersion time.Corrosion experiments demonstrate thatα-Mg was corroded preferentially,the eutectic phase and precipitates exhibit better corrosion resistance.The as-extruded alloy demonstrates uniform corrosion due to fine and homogeneous microstructure.
基金supported by the National Natural Science Foundation of China(No.21576188)
文摘Graphene oxide （GO） contains numerous functional groups that facilitate the intercalation of polar solvents. The properties and applications of GO are closely related to its interlayer spacing. We report on the changes in the interlayer spacing of GO after the adsorption of water molecules and the polar organic solvents C2H602 （EG）, C3HTNO （DMF）, C5H9NO （NMP）. Experiments were conducted to investigate the variations in the functional groups and structure of GO after solvent adsorp-tion, and they play a vital role in modeling and verifying the results of molecular dynamics simulation. The most stable GO structures are obtained through molecular dynamics simulation. The expansion of the interlayer spacing of GO after the adsorption of monolayer solvent molecules corresponds to the minimum three-dimensional size of the solvent molecules. The spatial arrangement of solvent molecules also contributes to the changes in interlayer spacing. Most adsorbed molecules are oriented parallel to the carbon plane of GO. However, as additional molecules are adsorbed into the interlaminations of GO, the adsorbed molecules are oriented perpendicular to the carbon plane of GO, and a large space forms between two GO interlayers. In addition, the role of large molecules in increasing interlayer spacing becomes more crucial than that of water molecules in the adsorption of binary solvent systems by GO.
基金supported by the Guangxi Natural Science Foundation (2018GXNSFAA294016)。
文摘A revision of the genus Chrysotus Meigen from Sichuan,China is presented.Sixteen species are recorded.One species is described as new to science:Chrysotus shuensis Liu&Yang sp.nov.
基金the National Natural Science Foundation of China (11871188, 12031019)。
文摘Let(X,φ) be a nonautonomous dynamical system.In this paper,we introduce the notions of packing topological entropy and measure-theoretical upper entropy for nonautonomous dynamical systems.Moreover,we establish the variational principle between the packing topological entropy and the measure-theoretical upper entropy.
基金Supported by the National Natural Science Foundation of China (Grant No.51672015)the National Key Research and Development Program of China (Grant Nos.2016YFC1102500 and 2017YFB0702100)+3 种基金the 111 Project (Grant No.B17002)and the Fundamental Research Funds for the Central Universitiessupported by the European Regional Development Fund in the IT4Innovations National Supercomputing Center—Path to Exascale Project (Grant No.CZ.02.1.01/0.0/0.0/16 013/0001791)within the Operational Programme for Research,Development and Education,and by the Large Infrastructures for Research,Experimental Development,and Innovation Project (Grant No.e-INFRA CZ-LM2018140) by the Ministry of Education,Youth,Sport of the Czech Republic。
文摘Diamond, cubic boron nitride(c-BN), silicon(Si), and germanium(Ge), as examples of typical strong covalent materials, have been extensively investigated in recent decades, owing to their fundamental importance in material science and industry. However, an in-depth analysis of the character of these materials' mechanical behaviors under harsh service environments, such as high pressure, has yet to be conducted. Based on several mechanical criteria, the effect of pressure on the mechanical properties of these materials is comprehensively investigated.It is demonstrated that, with respect to their intrinsic brittleness/ductile nature, all these materials exhibit ubiquitous pressure-enhanced ductility. By analyzing the strength variation under uniform deformation, together with the corresponding electronic structures, we reveal for the first time that the pressure-induced mechanical softening/weakening exhibits distinct characteristics between diamond and c-BN, owing to the differences in their abnormal charge-depletion evolution under applied strain, whereas a monotonous weakening phenomenon is observed in Si and Ge. Further investigation into dislocation-mediated plastic resistance indicates that the pressure-induced shuffle-set plane softening in diamond(c-BN), and weakening in Si(Ge), can be attributed to the reduction of antibonding states below the Fermi level, and an enhanced metallization, corresponding to the weakening of the bonds around the slipped plane with increasing pressure, respectively. These findings not only reveal the physical mechanism of pressure-induced softening/weakening in covalent materials, but also highlights the necessity of exploring strain-tunable electronic structures to emphasize the mechanical response in such covalent materials.
基金Supported by the Project of National Natural Science Foundation of China(31360068)the Project of Natural Science Foundation of Qinghai Provincial Department of Science and Technology(2017-ZJ-742).
文摘Platycladi Cacumen(Platycladus orientalis leaf)is a traditional Chinese medicine with a variety of medicinal values,and its efficacy has been recorded by many ancient books.Its chemical components mainly include flavonoids,volatile oil,tannins and so on.Pharmacological studies have confirmed that P.orientalis leaves have various pharmacological effects such as antibacterial,anti-oxidant,anti-tumor,hair growth promoting and hemostatic effects.Through review of the research on the chemical components and pharmacological effects of P.orientalis leaves,this study is intended to provide reference for the research,development and utilization of P.orientalis.
基金supported by the China Postdoctoral Science Foundation(No.2020M680325)the Chinese National Natural Science Fund(Nos.12172067 and 12072005)+4 种基金the Fundamental Research Funds for the Central Universities,China(No.2023CDJXY-007)the Aeronautical Science Foun-dation of China(No.2022Z0570Q9002)the Young Elite Sci-entists Sponsorship Program by CAST,China(No.2020QNRC001)the Chongqing Talent Plan,China(No.cstc2022ycjh-bgzxm0144)the Project of High-Level Talents Introduction of Hebei Province,China(No.2021HBQZYCSB009)。
文摘Many works have been made for predicting the failure of composite joints.However,there is still lack of method for multi-bolted composite joints subjected to the hygrothermal environment.In this work,a characteristic curve-based numerical framework is proposed,which includes two main steps and shows low computational cost.Firstly,a 3D finite element model considering hygrothermal effects is established to analyze the bolt-load distribution of multi-bolted joints.Secondly,a new characteristic curve considering the hygrothermal influence is used to obtain the failure pattern and strength of composite joints.The two-,three-and four-bolted composite joints with-55℃/dry(CTD),23℃/dry(RTD)and 70℃/wet(ETW)conditions are investigated.The test outcomes present good agreement with predicted results,which illustrates the effectiveness and applicability of the proposed method.Meanwhile,it is shown that the environmental condition affects the bolt-load ratio slightly,but does not change the location of the key loaded hole.Furthermore,deviations of the strengths in CTD and ETW conditions are about 5%and-16%from that in the RTD condition,respectively.The environmental condition does not affect the failure modes of two-and three-bolted joints,whereas changes the failure mode of the four-bolted joint.The proposed method is efficient,reliable and needs only linear elastic FE analysis,making it applicable for engineering practice.
基金supported by the National Key R&D Program of China(2023YFC2307500 and 2021YFC2701700)National Natural Science Foundation of China(82341115)+5 种基金Beijing Research Center for Respiratory Infectious Diseases(BJRID2024-003)Major Project of Guangzhou National Laboratory(GZNL2023A01001 and SRPG22-001)the National Science and Technology Infrastructure of China(National Pathogen Resource Center-NPRC-32)Y.B.is supported by the Youth Innovation Promotion Association of CAs(Y2021034)CAS Project for Young Scientists in Basic Research(YSBR-086)the Innovation Team and Talents Cultivation Program of the National Administration of Traditional Chinese Medicine(ZYYCXTD-D-202208).
文摘Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection often leads to pulmonary complications.Cardiovascular sequelae,including myocarditis and heart failure,have also been reported.Here,the study presents two fulminant myocarditis cases infected by SARS-CoV-2 exhibiting remarkable elevation of cardiac biomarkers without significant pulmonary injury,as determined by imaging examinations.Immunohistochemical staining reveals the viral antigen within cardiomyocytes,indicating that SARSCoV-2 could directly infect the myocardium.The full viral genomes from respiratory,anal,and myocardial specimens are obtained via next-generation sequencing.Phylogenetic analyses of the whole genome and spike gene indicate that viruses in the myocardium/pericardial effusion and anal swabs are closely related and cluster together yet diverge from those in the respiratory samples.In addition,unique mutations are found in the anal/myocardial strains compared to the respiratory strains,suggesting tissue-specific virus mutation and adaptation.These findings indicate genetically distinct SARS-CoV-2 variants have infiltrated and disseminated within myocardial tissues,independent of pulmonary injury,and point to different infection routes between the myocardium and respiratory tract,with myocardial infections potentially arising from intestinal infection.These findings highlight the potential for systemic SARS-CoV-2 infection and the importance of a thorough multi-organ assessment in patients for a comprehensive understanding of thepathogenesisof COVID-19.
基金supported by the National Natural Science Foundation of China(No.52271073)the Central Govern-ment Guided Special Program(No.2021ZYD0049)the Young Elite Scientists Sponsorship Program by CAST(No.2018QNRC001).
文摘Metal-organic framework[MOF,i.e.,NH_(2)-MIL-53(Al)]modified TiO_(2)(NMT)composite photoanodes were successfully prepared by hydrothermal synthesis and were used for the photoelectrochemical cathodic protection(PECCP)of nickel-plated magnesium alloy(Mg/Ni).Results showed that the synthesis tem-perature significantly impacted the morphology and PECCP performance of the NMT photoanodes.The NMT@150 photoanode prepared at a reaction temperature of 150℃exhibited the best PECCP perfor-mance and produced a current density of 1980μA cm^(-2)under visible light irradiation,which was 19.8 times higher than that of a single TiO_(2)photoanode.The composite photoanode could polarize the open circuit potential of the coupled Mg/Ni electrode to-876 mV and remain relatively stable within 35 h.XPS and EPR tests showed that a Z-scheme heterojunction was formed between the NH_(2)-MIL-53(Al)and TiO_(2)nanotubes,allowing the photogenerated electrons to accumulate mainly on the conduction band of NH_(2)-MIL-53(Al).The heterojunction greatly promoted the separation and transfer of photogenerated electron-hole in the NMT composite photoanode,significantly enhancing the PECCP performance for Mg/Ni.
基金supported by the National Natural Science Foundation of China(Nos.12264056 and 62164013)the Yunnan Expert Workstation Project(No.202205AF150008)the High-level Talent Promotion and Training Project of Kunming(No.2022SCP005)。
文摘Organic-inorganic hybrid perovskite formamidinium lead bromide nanosheet(FAPb Br_(3)NS)is regarded as a superior substance used to construct optoelectronic devices.However,its uncontrollable stability seriously affects its application in the field of photodetectors.In this paper,FAPb Br_(3)is combined with cadmium sulfide nanobelt(Cd S NB)to construct a hybrid device that greatly improves the stability and performance of the photodetector.The response of the FAPb Br_(3)NS/Cd S NB detector under 490 nm light illumination reaches 5712 A/W,while the response of the FAPb Br_(3)photodetector under equivalent conditions is only 25.45 A/W.The photocurrent of the FAPb Br_(3)NS/Cd S NB photodetector is nearly 80.25%of the initial device after exposure to air for 60 days.The difference in electric field distribution between the single material device and the composite device is simulated by the finite-difference time-domain method.It shows the advantages of composite devices in photoconductive gain and directly promotes the hybrid device performance.This paper presents a new possibility for high stability,fast response photodetectors.
基金supported by the State’s Key Project of Research and Development Plan of China(Grant No.2021YFD2000401)the Heilongjiang Province Engineering Science and Technology Major Project of China(Grant No.2020ZX17B01)the National Modern Agricultural Industry Technology System Project(Grant No.GARS-04).
文摘To effectively obtain the downforce of the gauge wheels in real time,mechanical models of the interaction among the ground,gauge wheels,gauge wheel arms,and depth adjustment lever were constructed.A measuring method was proposed for monitoring the downforce through a two-dimensional radial sensing device,and a corresponding prototype was designed.Through simulation analysis of the sensing device with ANSYS,a 45°angle was determined to exist between the strain gauge axis and the sensing device axis,and the Wheatstone bridging circuit of R1+R3−R5−R7(R stands for resistance strain gauge,different figures represent the strain gauge number)and R2+R4−R6−R8 was adopted.According to performance and calibration tests for the sensing device,the maximum interaction effect between the X and Y axes was 2.52%,and the output signal was stable and consistent.The standard error of the slope of the fitting equation of the downforce calculation model is 0.008.According to the field test,the average downforce of the gauge wheels was 1148,1017,843,and 713 N,at different sowing speeds of 6,8,10,and 12 km/h,respectively.The coefficients of variation were 0.40,0.41,0.62,and 0.71,respectively.The results indicate that the downforce fluctuation of the gauge wheels became more severe with increasing planting speed.Both the strain simulation analysis and field test verified that the measurement method is accurate and reliable,the performance of the sensing device is stable,the measurement method and sensing device meet the application requirements and lay a foundation for the research of accurate and stable control of downforce of no-till planter.
基金provided by Chinese Academy of Sciences,(Y9HIRLL100)National Natural Science Foundation of China,(11975289),Yan Cong.
文摘Background Sawtooth wave buncher is widely used in low-energy ion injection at cyclotron accelerators.Its performance significantly impacts on the intensity of ion beam delivered to experimental terminals.In order to meet the high-intensity requirement of physical experiments,we upgrade the existing B02 buncher in the axial injection line of the SFC with the dual-model sawtooth wave buncher for low-energy ion injection.Methods We use a three harmonics synthesis method in the dual-sawtooth wave buncher.First,we use three harmonics to generate a low-level sawtooth wave.Second,the low-level wave is amplified by a broadband amplifier to generate high voltage at a single-gap electrode.Third,the electrode is matched to the amplifier by a 1:9 transmission line transformer.Results The new buncher has been installed online since September 2022.Our tested results show that the buncher is capable of being operated at the full-frequency mode and half-frequency mode with the corresponding frequency ranging from 2.75 to 8.0 MHz and 5.5 to 16.0 MHz,respectively.The effective voltage can be up to 2.54 kV and 1.6 kV,respectively.Also,the sawtooth wave buncher works reliably,and a 4.5-8.6 times gain in the beam intensity is achieved.Conclusion By using the three-harmonic synthesis method,a new dual-mode high-voltage sawtooth wave buncher has been built.This sawtooth wave buncher has succeeded in being applied with the high buncher voltage over a wide frequency range with good reliability and stability.This newly-built sawtooth wave buncher significantly increases the ion beam current for low-energy ion injection at the HIRFL-SFC cyclotron.
