The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of...The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×10^(35) cm^(–2)·s^(–1) or higher.The STCF will produce a data sample about a factor of 100 larger than that of the presentτ-charm factory—the BEPCII,providing a unique platform for exploring the asymmetry of matter-antimatter(charge-parity violation),in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions,as well as searching for exotic hadrons and physics beyond the Standard Model.The STCF project in China is under development with an extensive R&D program.This document presents the physics opportunities at the STCF,describes conceptual designs of the STCF detector system,and discusses future plans for detector R&D and physics case studies.展开更多
An Al-12 Si/Al-3.5 Cu-1.5 Mg-1 Si bimetal with a good interface was successfully produced by selective laser melting(SLM).The SLM bimetal exhibits four successive zones along the building direction:an Al-12 Si zone,an...An Al-12 Si/Al-3.5 Cu-1.5 Mg-1 Si bimetal with a good interface was successfully produced by selective laser melting(SLM).The SLM bimetal exhibits four successive zones along the building direction:an Al-12 Si zone,an interfacial zone,a texture-strengthening zone and an Al-Cu-Mg-Si zone.The interfacial zone(<0.2 mm thick)displays an increasing size of the cells composed of eutectic Al-Si and a discontinuous cellular microstructure,resulting in the lowest hardness of the four zones.The texturestrengthening zone(around 0.3 mm thick)shows a remarkable variation of the hardness and<001>fiber texture.Electron backscatter diffraction analysis shows that the grains grow gradually from the interfacial zone to the Al-Cu-Mg-Si zone along the building direction.Additionally,a strong<001>fiber texture develops at the Al-Cu-Mg-Si side of the interfacial zone and disappears gradually along the building direction.The bimetal exhibits a room temperature yield strength of 267±10 MPa and an ultimate tensile strength of 369±15 MPa with elongation of 2.6±0.1%,revealing the potential of selective laser melting in manufacturing dissimilar materials.展开更多
The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on20...The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on2022 July 27.In this paper,we introduce the design and on-ground test results of the LEIA instrument.Using stateof-the-art Micro-Pore Optics(MPO),a wide field of view of 346 square degrees(18.6°×18.6°)of the X-ray imager is realized.An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons,and four large-format complementary metal-oxide semiconductor(CMOS)sensors,each of size 6 cm×6 cm,are used as the focal plane detectors.The instrument has an angular resolution of 4’-8’(in terms of FWHM)for the central focal spot of the point-spread function,and an effective area of 2-3 cm^(2) at 1 keV in essentially all the directions within the field of view.The detection passband is 0.5-4 keV in soft X-rays and the sensitivity is2-3×10^(-11) erg s^(-1) cm^(-2)(about 1 milliCrab)with a 1000 s observation.The total weight of LEIA is 56 kg and the power is 85 W.The satellite,with a design lifetime of 2 yr,operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes.LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation,and by optimizing the working setups of the instrumental parameters.In addition,LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band,albeit with limited useful observing time available.展开更多
Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic(FCC) structure,whereby a considerable strengthening can be attained by annealing o...Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic(FCC) structure,whereby a considerable strengthening can be attained by annealing of cold-worked alloys below the recrystallization temperature(T_(rx)).Microscopically,this hardening effect has been ascribed to several mechanisms,i.e.solute segregation to defects(dislocation and stacking fault) and short-range chemical ordering,etc.However,none of these mechanisms can well explain the anneal hardening recently observed in phase-pure and coarse-grained FCC-structured high-entropy alloys(HEAs).Here we report the observations,using high-resolution electron channeling contrast imaging and transmission electron microscopy,of profuse and stable dislocation substructures in a cold-rolled CoCrFeMnNi HEA subject to an annealing below T_(rx).The dislocation substructures are observed to be thermally stable up to T_(rx),which could arise from the chemical complexity of the high-entropy system where certain elemental diffusion retardation occurs.The microstructure feature is markedly different from that of conventional dilute solid solution alloys,in which dislocation substructures gradually vanish by recovery during annealing,leading to a strength drop.Furthermore,dilute addition of 2 at.% Al leads to a reduction in both microhardness and yield strength of the cold-rolled and subsequently annealed(≤500℃) HEA.This Al induced softening effect,could be associated with the anisotropic formation of dislocation substructure,resulting from enhanced dislocation planar slip due to glide plane softening effect.These findings suggest that the strength of HEAs can be tailored through the anneal hardening effect from dislocation substructure strengthening.展开更多
The static recrystallization and associated texture evolution were investigated in an extruded Mg-Zn-Gd alloy with bimodal microstructure based on a quasi-in-situ electron back-scatter diffraction(EBSD)method.The typi...The static recrystallization and associated texture evolution were investigated in an extruded Mg-Zn-Gd alloy with bimodal microstructure based on a quasi-in-situ electron back-scatter diffraction(EBSD)method.The typical rare earth(RE)texture formed during annealing,evolving from the bimodal microstructure with[1010]basal fiber texture that consisted of fine recrystallized(RXed)grains and coarse unrecrystallized(un RXed)grains elongated along the extrusion direction.In both RXed and un RXed regions,the RXed nucleation produced randomized orientations without preferred selection and the RXed grains with RE texture orientation had more intensive growth ability than those with basal fiber orientation,thereby leading to the preferred selection of RE texture orientation during grain growth.The relationships between stored strain energy,solute drag,grain growth and texture evolution are discussed in detail.This study provided direct evidence of the RE texture evolution in an extruded Mg-RE alloy,which assists in understanding the formation mechanisms for RE texture during extrusion and better developing wrought Mg alloys with improved formability.展开更多
Bulk density is an indicator of soil compaction subject to anthropogenic impact,essential to the interpretation of any nutrient budgets,especially to perform carbon inventories.It is so expensive to measure bulk densi...Bulk density is an indicator of soil compaction subject to anthropogenic impact,essential to the interpretation of any nutrient budgets,especially to perform carbon inventories.It is so expensive to measure bulk density in arctic/sub-arctic and there are relatively very few field measurements are available.Therefore,to establish a bulk density and SOC empirical relationship in Canada’s arctic and sub-arctic ecosystems,compiled all the bulk density and SOC measurements that are available in Northern Canada.In addition an attempt has been made for bulk density and SOC field measurement in Yellowknife and Lupin,to develop an empirical relationship for Canada’s arctic and sub-arctic.Relationships between bulk density(BD)and soil organic carbon(SOC)for mineral soil and organic soils(0–100 cm depth)were described by exponential functions.The best fit model,predictive bulk density(BDp),for mineral soil,(BDp=0.701+0.952 exp(0.29 SOC),n=702,R2=0.99);for organic soil(BDp=0.074+2.632 exp(0.076 SOC),n=674,R2=0.93).Different soil horizons have different bulk densities and may require different predictive equations,therefore,developed predictive best fit exponential equation for both mineral and organic soils together(BDp=0.071+1.322 exp(0.071 SOC),n=1376,R2=0.984),where X is a dummy variable with a value of 0 for surface peat(0–25 cm depth)and 1 for subsurface peat(25–175 cm).We recommend using the soil organic carbon density approach to estimate BD from SOC because it allows BD to be predicted without significant bias.展开更多
Deformation kinking as an uncommon plastic deformation mechanism has been reported in several materials while the relevant microstructure evolution and grain refinement behavior at a large strain remain unclear so far...Deformation kinking as an uncommon plastic deformation mechanism has been reported in several materials while the relevant microstructure evolution and grain refinement behavior at a large strain remain unclear so far.In this study,the issue was systematically investigated by utilizing cold forging to impose severe plastic deformation(SPD)on Ti-11 V metastableβ-Ti alloys.It is found that the formation of kink bands experiences dislocation gliding,pre-kinking and the ripening of pre-kinks in sequences.The kink bands are subsequently thickened through the coalescence of multiple kink bands in a manner of high accommodation.Ordinary dislocation slip is developed as a dominant deformation mechanism when deformation kinking is exhausted.The resulting grain refinement involves transverse breakdown and longitudinal splitting of dislocation walls and cells,which fragment kink bands into smallβ-blocks.Further refinement of theβ-blocks is still governed by dislocation activities,and finally nanograins with a diameter of~15 nm are produced at a large strain of 1.2.Alternatively,it is revealed that nanocrystallization is highly localized inside kink bands while the outer microstructure maintains original coarse structures.Such localized refinement characterization is ascribed to the intrinsic soft nature of kink bands,shown as low hardness in nanoindentation testing.The intrinsic softening of kink bands is uncovered to originate from the inner degraded dislocation density evidenced by both experimental measurement and theoretical calculation.These findings enrich fundamental understanding of deformation kinking,and shed some light on exploring the deformation accommodation mechanisms for metal materials at large strains.展开更多
A branch of high-frequency Alfvenic modes is observed on the HL-2A tokamak.The electromagnetic mode can be driven unstably in the plasma with an off-axis neutral beam heating.Its mode frequency keeps almost unchanged ...A branch of high-frequency Alfvenic modes is observed on the HL-2A tokamak.The electromagnetic mode can be driven unstably in the plasma with an off-axis neutral beam heating.Its mode frequency keeps almost unchanged or presents a slow-sweeping behavior,depending on the detail current evolution.The poloidal and toroidal mode numbers are𝑚m/n=1/1.The mode has a quite short duration(≤20 ms)and usually appears 5-10 ms after the neutral beam being injected into the plasma.Hybrid simulations based on M3D-K have also been carried out.The result suggests that co-passing energetic particles are responsible for the mode excitation.The simulated mode structures are localized nearby location of minimum safety factor(q_(min))and agree with the structures obtained through tomography of soft x-ray arrays.Further,the modes are localized in the continuum gap and their frequencies increase with variation of𝑞min in a wide range.Last but not least,the characteristic of unchanged frequency on experiment is also reproduced by the nonlinear simulation with a fixed safety factor.All those evidences indicate that the𝑛n=1 high-frequency mode may belong to a reversed shear Alfven eigenmode.展开更多
The experiment was conducted to as- sess the effects of dietary supplementation of Cu on the growth performance, digestive enzymes, tissue minerals and absorptive transporters in small intestinal mucosa of weanling pi...The experiment was conducted to as- sess the effects of dietary supplementation of Cu on the growth performance, digestive enzymes, tissue minerals and absorptive transporters in small intestinal mucosa of weanling pigs. One hundred crossbred pigs weaned at 28 ＋ 2 d of age were assigned randomly to one of the following diets with 5 replicates：corn-soy- bean basal diet with 10,100,175,250 mg/kg of Cu as CuSO4·5H20. The results showed that 250 mg/kg Cu had a positive effect （ P 〈 0.05） on average daily gain, daily feed intake and ratio of gain/feed. Com- pared to 10 mg/kg Cu, higher Cu had significant effect on the apparent digestibility of protein and fat （P 〈 0.05 ）. The supplementing of Cu improved am- ylase and lipase activity in jejunum content and lipase in pancreas （ P 〈 0.05） and had no effect on intestinalmorphology. The liver Cu elevated approximately 4- fold in pigs fed diet with 250 mg/kg Cu compared with pigs fed diet with 10 mg/kg Cu, no increases were observed in pigs receiving the lower level of Cu （100 and 175 mg/kg）. Both Fe and Zn contents in kidney and liver were not affected by Cu supplemen- tation. There was no positive effect （ P 〉0.05） of Cu supplementation on PepT1 （peptide transporter 1 ） and SGLT1 （sodium/glucose cotransporter） mRNA abundance in intestinal mucosa. However, higher sup- plementing level （250 mg/kg） significantly elevated the DMT1 （divalent metal transporter） mRNA abun- dance in duodenum mucosa. These results suggested that dietary supplementation with 250 mg/kg Cu could improve growth performance, nutrient digestibil- ity and intestinal enzyme activities of weanling pigs.展开更多
CoFe_(2)O_(4)/Pb(Zr_(0.53)Ti_(0.47))TO_(3)(abbreviated as CFO/PZT)multiferroic composite thick films were successfully fabricated on alumina substrate with gold bottom electrode by screen printing method at a low-sint...CoFe_(2)O_(4)/Pb(Zr_(0.53)Ti_(0.47))TO_(3)(abbreviated as CFO/PZT)multiferroic composite thick films were successfully fabricated on alumina substrate with gold bottom electrode by screen printing method at a low-sintering temperature.The processing included the modi fication and dispersion of ferromagnetic CFO powder and ferroelectric PZT powder,the preparation of uniform pastes,and the selection of proper annealing temperature for composite thick films.Transmission electron microscopic pictures(TEM)indicated the submicron meter of particles size for both CFO and PZT particles.After annealing at 900℃ for 1 h in air,tape test con firmed the quality of multiferroic thick films as well as pure CFO and PZT films.X-ray diffraction(XRD)showed a coexistence of CFO and PZT phases;furthermore,a smooth surface was observed through scanning electron microscopic(SEM)pictures along with the sharp cross-sectional picture,indicative of 100m of film thickness.Ferromagnetic and ferroelectric properties were observed in CFO/PZT films simultaneously at room temperature.Compared with the reported CFO/PZT multiferrroic thin films,the present ferromagnetic property was closing to that of the chemical solgel synthesized film and even that from the physical pulsed laser deposition technique.However,the ferroelectric property showed a degenerated behavior,possible reasons for this was discussed and further optimization was also proposed for the potential multifunctional application.展开更多
Canada’s Arctic and sub-arctic consist 46%of Canada’s landmass and contain 45%of the total soil organic carbon(SOC).Pronounced climate warming and increasing human disturbances could induce the release of this SOC t...Canada’s Arctic and sub-arctic consist 46%of Canada’s landmass and contain 45%of the total soil organic carbon(SOC).Pronounced climate warming and increasing human disturbances could induce the release of this SOC to the atmosphere as greenhouse gases.Canada is committed to estimating and reporting the greenhouse gases emissions and removals induced by land use change in the Arctic and sub-arctic.To assess the uncertainty of the estimate,we compiled a site-measured SOC database for Canada’s north,and used it to compare with a polygon database,that will be used for estimating SOC for the UNFCCC reporting.In 10 polygons where 3 or more measured sites were well located in each polygon,the site-averaged SOC content agreed with the polygon data within±33%for the top 30 cm and within±50%for the top 1 m soil.If we directly compared the SOC of the 382 measured sites with the polygon mean SOC,there was poor agreement:The relative error was less than 50%at 40%of the sites,and less than 100%at 68%of the sites.The relative errors were more than 400%at 10%of the sites.These comparisons indicate that the polygon database is too coarse to represent the SOC conditions for individual sites.The difference is close to the uncertainty range for reporting.The spatial database could be improved by relating site and polygon SOC data with more easily observable surface features that can be identified and derived from remote sensing imagery.展开更多
A localized space-time method of fundamental solutions(LSTMFS)is extended for solving three-dimensional transient diffusion problems in this paper.The interval segmentation in temporal direction is developed for the a...A localized space-time method of fundamental solutions(LSTMFS)is extended for solving three-dimensional transient diffusion problems in this paper.The interval segmentation in temporal direction is developed for the accurate simulation of long-time-dependent diffusion problems.In the LSTMFS,the whole space-time domain with nodes arranged i divided into a series of overlapping subdomains with a simple geometry.In each subdomain,the conventional method of fundamental solutions is utilized and the coefficients associated with the considered domain can be explicitly determined.By calculating a combined sparse matrix system,the value at any node inside the space-time domain can be obtained.Numerical experi-ments demonstrate that high accuracy and efficiency can be simultaneously achieved via the LSTMFS,even for the problems defined on a long-time and quite complex computational domain.展开更多
In the practical magneto opticaldisk productionline,alloysputteringtargetisalwaysusedtosputter recording film , whileinlaid targetisrarely used .In ourlaboratory,a seriesof al loy targets forsputtering magneto- opti...In the practical magneto opticaldisk productionline,alloysputteringtargetisalwaysusedtosputter recording film , whileinlaid targetisrarely used .In ourlaboratory,a seriesof al loy targets forsputtering magneto- optical recording film were prepared and theeffect ofcomposition andsputtering parameterson magneto opticalpropertiesarestudied . Thesputter ing rateof Al,Siand Tb Fe Co( Mo) undertheconditionsof differentsputtering powerandN2 Argasflux weredetermined and baseontheresults,a variablecomposition andthickness of SiNcan beobtained by meansof regulating sputtering power and gasflux, kindsof Mosputtering filmsareobtained under differentsputtering power and gasflux, and Kerrloop lineofthese magneto opticalfilmsare measuredto acquiretheir propertiessuch as Kerrrota tion,then ,theeffectofsputteringtechnology on Kerrrotationisdiscussed .展开更多
Introduction Operation target beam power of China Spallation Neutron Source(CSNS),as the China's first 100 kW beam power pulsed neutron source,is now larger than 80 kW.During the beam power upgrading process of CS...Introduction Operation target beam power of China Spallation Neutron Source(CSNS),as the China's first 100 kW beam power pulsed neutron source,is now larger than 80 kW.During the beam power upgrading process of CSNS to 50 kW from 2018 to 2019,many improvements have been made for the front end of CSNS.Results The improvements mainly focus on solving the problems of ion source instability and the radio frequency quadrupole(RFQ)sparking caused by the pre-chopped beam into RFQ.展开更多
Background:Bioenergy therapies(such as Qigong,Reiki,Yoga,Pranic healing,and Therapeutic touch)have reported benefits for cancer patients,but few randomized control trials were done to verify their efficacy.It is belie...Background:Bioenergy therapies(such as Qigong,Reiki,Yoga,Pranic healing,and Therapeutic touch)have reported benefits for cancer patients,but few randomized control trials were done to verify their efficacy.It is believed that laboratory study of inhibito- ry effects of bio-energy therapies on cancer growth may lead to an understanding of the true efficacy of bio-energy and create a foun- dation for future clinical trials.Methods:Typical in-vitro study involved randomly dividing lab-prepared cancer cells into different groups with one being treated by bio-energy therapy and one or more as control groups.Sometimes,controls were treated by a sham healer.Typical in vivo study involved injecting or implanting cancerous cells into mice,then randomly dividing them into various groups.The control could be either non-treatment or sham treatment;the outcomes include tumor size or survival time.Results:Most studies demonstrated some inhibitory effects ofbioenergy therapies on the growth of cancer cells in comparison with control.The in vivo studies reported that the bio-energy treated group had significantly slower tumor growth or longer survival lives than those in the control.One study reported survival with a normal life cycle instead of dying in 3 weeks,and cancer-infected mice developed immune response to the same breast cancer.However,researchers are confronted with methodological challenges in choosing appropriate con- trois,minimizing contamination,and replicating study outcomes.Conclusion:Encouraging evidence suggests bioenergy may have inhibitory effects on cancer growth,or prolong the life of cancer-infected animals,although improvement is needed in research design and replication of the findings.Bioenergy for cancer treatment is an area that is often neglected by mainstream medicine and research, and it should be seriously examined and considered as an important supplement to conventional cancer treatment.展开更多
The main characteristics of glass, polymethyl methacrylate (PMMA) and polycarbon ate (PC) were presented. The transmittance of glass, PMMA and PC was measured by the UV-VIS spectroscopy analysis. PMMA and PC have the ...The main characteristics of glass, polymethyl methacrylate (PMMA) and polycarbon ate (PC) were presented. The transmittance of glass, PMMA and PC was measured by the UV-VIS spectroscopy analysis. PMMA and PC have the advantages of higher tra nsparency, higher resistance and lower density. It is indicated that both PMMA a nd PC are suitable for encapsulating solar minimodules.展开更多
The kinetic effects of thermal particles and fast ions on internal kink(IK)mode are numerically investigated by the MHD-kinetic hybrid code MARS-K.It is shown that either thermal particles or fast ions have stabilizin...The kinetic effects of thermal particles and fast ions on internal kink(IK)mode are numerically investigated by the MHD-kinetic hybrid code MARS-K.It is shown that either thermal particles or fast ions have stabilizing influence on IK.However,the former can not fully stabilize IK,and the later can suppress the IK.In addition,the synergistic effect from thermal particles and fast ions induces more stronger damping on IK.The kinetic effects from particles significantly raise the critical value of poloidal beta(βpcrit)for driving IK in the toroidal plasma.This implies a method of controlling IK or sawtooth in the high-βp discharge scenario of tokamak.It is noted that,at the q=1 rational surface,mode structure becomes more sharp due to the self-consistent modification by particles’kinetic effect.展开更多
基金supported by the National Key R&D Program of China under Contract No.2022YFA1602200the International Partnership Program of the Chineses Academy of Sciences under Grant No.211134KYSB20200057the STCF Key Technology Research and Development Project.
文摘The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×10^(35) cm^(–2)·s^(–1) or higher.The STCF will produce a data sample about a factor of 100 larger than that of the presentτ-charm factory—the BEPCII,providing a unique platform for exploring the asymmetry of matter-antimatter(charge-parity violation),in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions,as well as searching for exotic hadrons and physics beyond the Standard Model.The STCF project in China is under development with an extensive R&D program.This document presents the physics opportunities at the STCF,describes conceptual designs of the STCF detector system,and discusses future plans for detector R&D and physics case studies.
基金supported by the Shenzhen Peacock Innovation Project(KQJSCX20170327150948772,KQJSCX20170727101223535,and KQJSCX20170327151307811)the Key Project Fund for Science and Technology Development of Guangdong Province(2017B090911014)+1 种基金support was provided by the European Research Council(ERC)under the ERC Advanced Grant INTELHYB(ERC-2013-ADG-340025)the National Natural Science Foundation of China(51771123)。
文摘An Al-12 Si/Al-3.5 Cu-1.5 Mg-1 Si bimetal with a good interface was successfully produced by selective laser melting(SLM).The SLM bimetal exhibits four successive zones along the building direction:an Al-12 Si zone,an interfacial zone,a texture-strengthening zone and an Al-Cu-Mg-Si zone.The interfacial zone(<0.2 mm thick)displays an increasing size of the cells composed of eutectic Al-Si and a discontinuous cellular microstructure,resulting in the lowest hardness of the four zones.The texturestrengthening zone(around 0.3 mm thick)shows a remarkable variation of the hardness and<001>fiber texture.Electron backscatter diffraction analysis shows that the grains grow gradually from the interfacial zone to the Al-Cu-Mg-Si zone along the building direction.Additionally,a strong<001>fiber texture develops at the Al-Cu-Mg-Si side of the interfacial zone and disappears gradually along the building direction.The bimetal exhibits a room temperature yield strength of 267±10 MPa and an ultimate tensile strength of 369±15 MPa with elongation of 2.6±0.1%,revealing the potential of selective laser melting in manufacturing dissimilar materials.
基金supported by the Einstein Probe project,a mission in the Strategic Priority Program on Space Science of CAS(grant Nos.XDA15310000,XDA15052100)in part been supported by the European Union’s Horizon 2020 Program under the AHEAD2020 project(grant No.871158).
文摘The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on2022 July 27.In this paper,we introduce the design and on-ground test results of the LEIA instrument.Using stateof-the-art Micro-Pore Optics(MPO),a wide field of view of 346 square degrees(18.6°×18.6°)of the X-ray imager is realized.An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons,and four large-format complementary metal-oxide semiconductor(CMOS)sensors,each of size 6 cm×6 cm,are used as the focal plane detectors.The instrument has an angular resolution of 4’-8’(in terms of FWHM)for the central focal spot of the point-spread function,and an effective area of 2-3 cm^(2) at 1 keV in essentially all the directions within the field of view.The detection passband is 0.5-4 keV in soft X-rays and the sensitivity is2-3×10^(-11) erg s^(-1) cm^(-2)(about 1 milliCrab)with a 1000 s observation.The total weight of LEIA is 56 kg and the power is 85 W.The satellite,with a design lifetime of 2 yr,operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes.LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation,and by optimizing the working setups of the instrumental parameters.In addition,LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band,albeit with limited useful observing time available.
基金financially supported by the National Natural Science Foundation of China (No. 52001120)the Fundamental Research Funds for the Central Universities (No. 531118010450)+10 种基金the Hundred Talent Program of Hunan Provincethe State Key Laboratory of Powder Metallurgy,Central South University,Changshathe State Key Laboratory of Advanced Metals and Materials(No. 2021-Z09)University of Science&Technology Beijing,Chinasupported by the National Natural Science Foundation of China (No. 51801060)supported by the Swedish Research Councilsupported by the National Science Foundation under Contract (No. DMR-1408722)sponsored by the Whiting School of EngineeringJohns Hopkins Universityfunded by the National Key Research and Development Program of China (No. 2016YFB0300801)the National NaturalScience Foundation of China (Nos. 51831004, 11427806, 51671082,51471067)。
文摘Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic(FCC) structure,whereby a considerable strengthening can be attained by annealing of cold-worked alloys below the recrystallization temperature(T_(rx)).Microscopically,this hardening effect has been ascribed to several mechanisms,i.e.solute segregation to defects(dislocation and stacking fault) and short-range chemical ordering,etc.However,none of these mechanisms can well explain the anneal hardening recently observed in phase-pure and coarse-grained FCC-structured high-entropy alloys(HEAs).Here we report the observations,using high-resolution electron channeling contrast imaging and transmission electron microscopy,of profuse and stable dislocation substructures in a cold-rolled CoCrFeMnNi HEA subject to an annealing below T_(rx).The dislocation substructures are observed to be thermally stable up to T_(rx),which could arise from the chemical complexity of the high-entropy system where certain elemental diffusion retardation occurs.The microstructure feature is markedly different from that of conventional dilute solid solution alloys,in which dislocation substructures gradually vanish by recovery during annealing,leading to a strength drop.Furthermore,dilute addition of 2 at.% Al leads to a reduction in both microhardness and yield strength of the cold-rolled and subsequently annealed(≤500℃) HEA.This Al induced softening effect,could be associated with the anisotropic formation of dislocation substructure,resulting from enhanced dislocation planar slip due to glide plane softening effect.These findings suggest that the strength of HEAs can be tailored through the anneal hardening effect from dislocation substructure strengthening.
基金the financial supports from the National Natural Science Foundation of China(NSFC,No.52005340 and 51601193)State Key Program of National Natural Science of China(No.51531002)+3 种基金National Key Research and Development Program of China(No.2016YFB0301104)National Basic Research Program of China(973 Program,No.2013CB632202)Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110541)Shenzhen Bureau of Industry and Information Technology(No.ZDYBH201900000008)。
文摘The static recrystallization and associated texture evolution were investigated in an extruded Mg-Zn-Gd alloy with bimodal microstructure based on a quasi-in-situ electron back-scatter diffraction(EBSD)method.The typical rare earth(RE)texture formed during annealing,evolving from the bimodal microstructure with[1010]basal fiber texture that consisted of fine recrystallized(RXed)grains and coarse unrecrystallized(un RXed)grains elongated along the extrusion direction.In both RXed and un RXed regions,the RXed nucleation produced randomized orientations without preferred selection and the RXed grains with RE texture orientation had more intensive growth ability than those with basal fiber orientation,thereby leading to the preferred selection of RE texture orientation during grain growth.The relationships between stored strain energy,solute drag,grain growth and texture evolution are discussed in detail.This study provided direct evidence of the RE texture evolution in an extruded Mg-RE alloy,which assists in understanding the formation mechanisms for RE texture during extrusion and better developing wrought Mg alloys with improved formability.
文摘Bulk density is an indicator of soil compaction subject to anthropogenic impact,essential to the interpretation of any nutrient budgets,especially to perform carbon inventories.It is so expensive to measure bulk density in arctic/sub-arctic and there are relatively very few field measurements are available.Therefore,to establish a bulk density and SOC empirical relationship in Canada’s arctic and sub-arctic ecosystems,compiled all the bulk density and SOC measurements that are available in Northern Canada.In addition an attempt has been made for bulk density and SOC field measurement in Yellowknife and Lupin,to develop an empirical relationship for Canada’s arctic and sub-arctic.Relationships between bulk density(BD)and soil organic carbon(SOC)for mineral soil and organic soils(0–100 cm depth)were described by exponential functions.The best fit model,predictive bulk density(BDp),for mineral soil,(BDp=0.701+0.952 exp(0.29 SOC),n=702,R2=0.99);for organic soil(BDp=0.074+2.632 exp(0.076 SOC),n=674,R2=0.93).Different soil horizons have different bulk densities and may require different predictive equations,therefore,developed predictive best fit exponential equation for both mineral and organic soils together(BDp=0.071+1.322 exp(0.071 SOC),n=1376,R2=0.984),where X is a dummy variable with a value of 0 for surface peat(0–25 cm depth)and 1 for subsurface peat(25–175 cm).We recommend using the soil organic carbon density approach to estimate BD from SOC because it allows BD to be predicted without significant bias.
基金supported by the National Natural Science Foundation of China(Nos.51871176,51722104,51922017,51972009)the National Key Research and Development Program of China(Nos.2017YFA0700701,2017YFB0702301)+2 种基金the 111 Project 2.0 of China(No.PB2018008)Natural Science Basic Research Plan in Shaanxi Province of China(No.2018JM5098)the Fundamental Research Funds for the Central Universities(No.xtr022019004)。
文摘Deformation kinking as an uncommon plastic deformation mechanism has been reported in several materials while the relevant microstructure evolution and grain refinement behavior at a large strain remain unclear so far.In this study,the issue was systematically investigated by utilizing cold forging to impose severe plastic deformation(SPD)on Ti-11 V metastableβ-Ti alloys.It is found that the formation of kink bands experiences dislocation gliding,pre-kinking and the ripening of pre-kinks in sequences.The kink bands are subsequently thickened through the coalescence of multiple kink bands in a manner of high accommodation.Ordinary dislocation slip is developed as a dominant deformation mechanism when deformation kinking is exhausted.The resulting grain refinement involves transverse breakdown and longitudinal splitting of dislocation walls and cells,which fragment kink bands into smallβ-blocks.Further refinement of theβ-blocks is still governed by dislocation activities,and finally nanograins with a diameter of~15 nm are produced at a large strain of 1.2.Alternatively,it is revealed that nanocrystallization is highly localized inside kink bands while the outer microstructure maintains original coarse structures.Such localized refinement characterization is ascribed to the intrinsic soft nature of kink bands,shown as low hardness in nanoindentation testing.The intrinsic softening of kink bands is uncovered to originate from the inner degraded dislocation density evidenced by both experimental measurement and theoretical calculation.These findings enrich fundamental understanding of deformation kinking,and shed some light on exploring the deformation accommodation mechanisms for metal materials at large strains.
基金supported by the National Key R&D Program of China(Grant No.2019YFE03020000)the National Natu ral Science Foundation of China(Grant No.12125502)+1 种基金the Sichuan Science and Technology Program(Grants No.2020JDJQ0070)the Natural Science Foundation of Sichuan(Grant No.2022NSFSC1823).
文摘A branch of high-frequency Alfvenic modes is observed on the HL-2A tokamak.The electromagnetic mode can be driven unstably in the plasma with an off-axis neutral beam heating.Its mode frequency keeps almost unchanged or presents a slow-sweeping behavior,depending on the detail current evolution.The poloidal and toroidal mode numbers are𝑚m/n=1/1.The mode has a quite short duration(≤20 ms)and usually appears 5-10 ms after the neutral beam being injected into the plasma.Hybrid simulations based on M3D-K have also been carried out.The result suggests that co-passing energetic particles are responsible for the mode excitation.The simulated mode structures are localized nearby location of minimum safety factor(q_(min))and agree with the structures obtained through tomography of soft x-ray arrays.Further,the modes are localized in the continuum gap and their frequencies increase with variation of𝑞min in a wide range.Last but not least,the characteristic of unchanged frequency on experiment is also reproduced by the nonlinear simulation with a fixed safety factor.All those evidences indicate that the𝑛n=1 high-frequency mode may belong to a reversed shear Alfven eigenmode.
基金supported by Program for Changjiang Scholars and In-novative Research Team in University with grant No. IRTO555-5,China Ministry of Education
文摘The experiment was conducted to as- sess the effects of dietary supplementation of Cu on the growth performance, digestive enzymes, tissue minerals and absorptive transporters in small intestinal mucosa of weanling pigs. One hundred crossbred pigs weaned at 28 ＋ 2 d of age were assigned randomly to one of the following diets with 5 replicates：corn-soy- bean basal diet with 10,100,175,250 mg/kg of Cu as CuSO4·5H20. The results showed that 250 mg/kg Cu had a positive effect （ P 〈 0.05） on average daily gain, daily feed intake and ratio of gain/feed. Com- pared to 10 mg/kg Cu, higher Cu had significant effect on the apparent digestibility of protein and fat （P 〈 0.05 ）. The supplementing of Cu improved am- ylase and lipase activity in jejunum content and lipase in pancreas （ P 〈 0.05） and had no effect on intestinalmorphology. The liver Cu elevated approximately 4- fold in pigs fed diet with 250 mg/kg Cu compared with pigs fed diet with 10 mg/kg Cu, no increases were observed in pigs receiving the lower level of Cu （100 and 175 mg/kg）. Both Fe and Zn contents in kidney and liver were not affected by Cu supplemen- tation. There was no positive effect （ P 〉0.05） of Cu supplementation on PepT1 （peptide transporter 1 ） and SGLT1 （sodium/glucose cotransporter） mRNA abundance in intestinal mucosa. However, higher sup- plementing level （250 mg/kg） significantly elevated the DMT1 （divalent metal transporter） mRNA abun- dance in duodenum mucosa. These results suggested that dietary supplementation with 250 mg/kg Cu could improve growth performance, nutrient digestibil- ity and intestinal enzyme activities of weanling pigs.
基金This work was supported by the tier-2 research grant of ARC 04/06 funded by Ministry of Education,Singapore.
文摘CoFe_(2)O_(4)/Pb(Zr_(0.53)Ti_(0.47))TO_(3)(abbreviated as CFO/PZT)multiferroic composite thick films were successfully fabricated on alumina substrate with gold bottom electrode by screen printing method at a low-sintering temperature.The processing included the modi fication and dispersion of ferromagnetic CFO powder and ferroelectric PZT powder,the preparation of uniform pastes,and the selection of proper annealing temperature for composite thick films.Transmission electron microscopic pictures(TEM)indicated the submicron meter of particles size for both CFO and PZT particles.After annealing at 900℃ for 1 h in air,tape test con firmed the quality of multiferroic thick films as well as pure CFO and PZT films.X-ray diffraction(XRD)showed a coexistence of CFO and PZT phases;furthermore,a smooth surface was observed through scanning electron microscopic(SEM)pictures along with the sharp cross-sectional picture,indicative of 100m of film thickness.Ferromagnetic and ferroelectric properties were observed in CFO/PZT films simultaneously at room temperature.Compared with the reported CFO/PZT multiferrroic thin films,the present ferromagnetic property was closing to that of the chemical solgel synthesized film and even that from the physical pulsed laser deposition technique.However,the ferroelectric property showed a degenerated behavior,possible reasons for this was discussed and further optimization was also proposed for the potential multifunctional application.
基金This study is supported by a joint project between Environment Canada and Natural Resources Canada for estimation of greenhouse gases emissions and removals from land use changes over Canada’s Arctic and sub-arctic,and it is also supported by the climate change program in Natural Resources Canada.
文摘Canada’s Arctic and sub-arctic consist 46%of Canada’s landmass and contain 45%of the total soil organic carbon(SOC).Pronounced climate warming and increasing human disturbances could induce the release of this SOC to the atmosphere as greenhouse gases.Canada is committed to estimating and reporting the greenhouse gases emissions and removals induced by land use change in the Arctic and sub-arctic.To assess the uncertainty of the estimate,we compiled a site-measured SOC database for Canada’s north,and used it to compare with a polygon database,that will be used for estimating SOC for the UNFCCC reporting.In 10 polygons where 3 or more measured sites were well located in each polygon,the site-averaged SOC content agreed with the polygon data within±33%for the top 30 cm and within±50%for the top 1 m soil.If we directly compared the SOC of the 382 measured sites with the polygon mean SOC,there was poor agreement:The relative error was less than 50%at 40%of the sites,and less than 100%at 68%of the sites.The relative errors were more than 400%at 10%of the sites.These comparisons indicate that the polygon database is too coarse to represent the SOC conditions for individual sites.The difference is close to the uncertainty range for reporting.The spatial database could be improved by relating site and polygon SOC data with more easily observable surface features that can be identified and derived from remote sensing imagery.
基金the Fundamental Research Funds for the Central Universities(Grants B200203009 and B200202126)the Natural Science Foundation of Jiangsu Province(Grant BK20190073)+2 种基金the State Key Laboratory of Acoustics,Chinese Academy of Sciences(Grant SKLA202001)the State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,Shijiazhuang Tiedao University(Grant KF2020-22)the China Postdoctoral Science Foundation(Grants 2017M611669 and 2018T110430).
文摘A localized space-time method of fundamental solutions(LSTMFS)is extended for solving three-dimensional transient diffusion problems in this paper.The interval segmentation in temporal direction is developed for the accurate simulation of long-time-dependent diffusion problems.In the LSTMFS,the whole space-time domain with nodes arranged i divided into a series of overlapping subdomains with a simple geometry.In each subdomain,the conventional method of fundamental solutions is utilized and the coefficients associated with the considered domain can be explicitly determined.By calculating a combined sparse matrix system,the value at any node inside the space-time domain can be obtained.Numerical experi-ments demonstrate that high accuracy and efficiency can be simultaneously achieved via the LSTMFS,even for the problems defined on a long-time and quite complex computational domain.
文摘In the practical magneto opticaldisk productionline,alloysputteringtargetisalwaysusedtosputter recording film , whileinlaid targetisrarely used .In ourlaboratory,a seriesof al loy targets forsputtering magneto- optical recording film were prepared and theeffect ofcomposition andsputtering parameterson magneto opticalpropertiesarestudied . Thesputter ing rateof Al,Siand Tb Fe Co( Mo) undertheconditionsof differentsputtering powerandN2 Argasflux weredetermined and baseontheresults,a variablecomposition andthickness of SiNcan beobtained by meansof regulating sputtering power and gasflux, kindsof Mosputtering filmsareobtained under differentsputtering power and gasflux, and Kerrloop lineofthese magneto opticalfilmsare measuredto acquiretheir propertiessuch as Kerrrota tion,then ,theeffectofsputteringtechnology on Kerrrotationisdiscussed .
文摘Introduction Operation target beam power of China Spallation Neutron Source(CSNS),as the China's first 100 kW beam power pulsed neutron source,is now larger than 80 kW.During the beam power upgrading process of CSNS to 50 kW from 2018 to 2019,many improvements have been made for the front end of CSNS.Results The improvements mainly focus on solving the problems of ion source instability and the radio frequency quadrupole(RFQ)sparking caused by the pre-chopped beam into RFQ.
文摘Background:Bioenergy therapies(such as Qigong,Reiki,Yoga,Pranic healing,and Therapeutic touch)have reported benefits for cancer patients,but few randomized control trials were done to verify their efficacy.It is believed that laboratory study of inhibito- ry effects of bio-energy therapies on cancer growth may lead to an understanding of the true efficacy of bio-energy and create a foun- dation for future clinical trials.Methods:Typical in-vitro study involved randomly dividing lab-prepared cancer cells into different groups with one being treated by bio-energy therapy and one or more as control groups.Sometimes,controls were treated by a sham healer.Typical in vivo study involved injecting or implanting cancerous cells into mice,then randomly dividing them into various groups.The control could be either non-treatment or sham treatment;the outcomes include tumor size or survival time.Results:Most studies demonstrated some inhibitory effects ofbioenergy therapies on the growth of cancer cells in comparison with control.The in vivo studies reported that the bio-energy treated group had significantly slower tumor growth or longer survival lives than those in the control.One study reported survival with a normal life cycle instead of dying in 3 weeks,and cancer-infected mice developed immune response to the same breast cancer.However,researchers are confronted with methodological challenges in choosing appropriate con- trois,minimizing contamination,and replicating study outcomes.Conclusion:Encouraging evidence suggests bioenergy may have inhibitory effects on cancer growth,or prolong the life of cancer-infected animals,although improvement is needed in research design and replication of the findings.Bioenergy for cancer treatment is an area that is often neglected by mainstream medicine and research, and it should be seriously examined and considered as an important supplement to conventional cancer treatment.
文摘The main characteristics of glass, polymethyl methacrylate (PMMA) and polycarbon ate (PC) were presented. The transmittance of glass, PMMA and PC was measured by the UV-VIS spectroscopy analysis. PMMA and PC have the advantages of higher tra nsparency, higher resistance and lower density. It is indicated that both PMMA a nd PC are suitable for encapsulating solar minimodules.
基金the National Key R&D Program of China(Grant No.2019YFE03050003)the National Magnetic Confinement Fusion Science Program(Grant No.2018YFE0304103)the National Natural Science Foundation of China(Grant Nos.11775067 and11905067)。
文摘The kinetic effects of thermal particles and fast ions on internal kink(IK)mode are numerically investigated by the MHD-kinetic hybrid code MARS-K.It is shown that either thermal particles or fast ions have stabilizing influence on IK.However,the former can not fully stabilize IK,and the later can suppress the IK.In addition,the synergistic effect from thermal particles and fast ions induces more stronger damping on IK.The kinetic effects from particles significantly raise the critical value of poloidal beta(βpcrit)for driving IK in the toroidal plasma.This implies a method of controlling IK or sawtooth in the high-βp discharge scenario of tokamak.It is noted that,at the q=1 rational surface,mode structure becomes more sharp due to the self-consistent modification by particles’kinetic effect.
