The ability to generate high pressures in a large-volume press(LVP)is crucial for the study of matter under extreme conditions.Here,we have achieved ultrahigh pressures of and 50 GPa,respectively,at room temperature a...The ability to generate high pressures in a large-volume press(LVP)is crucial for the study of matter under extreme conditions.Here,we have achieved ultrahigh pressures of and 50 GPa,respectively,at room temperature and a high temperature of 1900 K∼60within a millimeter-sized sample volume in a Kawai-type LVP(KLVP)using hard tungsten carbide(WC)and newly designed assem-blies.The introduction of electroconductive polycrystalline boron-doped diamond and dense alumina wrapped with Cu foils into a large conventional cell assembly enables the detection of resistance variations in the Fe_(2)O_(3) pressure standard upon compression.The efficiency of pressure generation in the newly developed cell assembly equipped with conventional ZK10F WC anvils is significantly higher than that of conventional assemblies with some ultrahard or tapered WC anvils.Our study has enabled the routine gener-ation of pressures exceeding 50 GPa within a millimeter-sized sample chamber that have been inaccessible with traditional KLVPs.This advance in high-pressure technology not only breaks a record for pressure generation in traditional KLVPs,but also opens up new avenues for exploration of the properties of the Earth’s deep interior and for the synthesis of novel materials at extreme high pressures.展开更多
How to achieve high-entropy alloys(HEAs)with ultrahigh strength and ductility is a challenging issue.Precipitation strengthening is one of the methods to significantly enhance strength,but unfortunately,ductility will...How to achieve high-entropy alloys(HEAs)with ultrahigh strength and ductility is a challenging issue.Precipitation strengthening is one of the methods to significantly enhance strength,but unfortunately,ductility will be lost.To overcome the strength-ductility trade-off,the strategy of this study is to induce the formation of high-density nanoprecipitates through dual aging(DA),triggering multiple deformation mechanisms,to obtain HEAs with ultrahigh strength and ductility.First,the effect of precold deformation on precipitation behavior was studied using Ni_(35)(CoFe)_(55)V_(5)Nb_(5)(at.%)HEAas the object.The results reveal that the activation energy of recrystallization is 112.2 kJ/mol.As the precold-deformation amount increases from 15%to 65%,the activation energy of precipitation gradually decreases from 178.8 to 159.7 kJ/mol.The precipitation time shortens,the size of the nanoprecipitate decreases,and the density increases.Subsequently,the thermal treatment parameters were optimized,and the DA process was customized based on the effect of precold deformation on precipitation behavior.High-density L1_(2) nanoprecipitates(~3.21×10^(25) m^(-3))were induced in the 65% precold-deformed HEA,which led to the simultaneous formation of twins and stacking fault(SF)networks during deformation.The yield strength(YS),ultimate tensile strength,and ductility of the DA-HEA are~2.0 GPa,~2.2 GPa,and~12.3%,respectively.Compared with the solid solution HEA,the YS of the DA-HEA increased by 1,657 MPa,possessing an astonishing increase of~440%.The high YS stems from the precipitation strengthening contributed by the L1_(2) nanoprecipitates and the dislocation strengthening contributed by precold deformation.The synergistically enhanced ductility stems from the high strain-hardening ability under the dual support of twinning-induced plasticity and SF-induced plasticity.展开更多
Ultrahigh pressure generation at high temperatures is technologically challenging for large sample volumes.In this study,we successfully generated pressures of 37.3-40.4 GPa at 1900-2100 K in a Walker-type large-volum...Ultrahigh pressure generation at high temperatures is technologically challenging for large sample volumes.In this study,we successfully generated pressures of 37.3-40.4 GPa at 1900-2100 K in a Walker-type large-volume press(LVP).Expansion of the pressure range at high temperatures was achieved by adapting newly designed ZK01F tungsten carbide(WC)anvils with tapered surfaces and using cell assemblies with an^(-1) mm^(3) sample volume and hard materials,as well as by applying certain adjustments to the apparatus.The pressure efficiencies of the different types of WC anvils and cell assemblies were also studied.Using the above-mentioned techniques,we successfully synthesized and characterized bulk samples of nearly pure sp3-hybridized ultrahard amorphous carbon,core-shell nanocrystals with high Néel temperatures,as well as large-sized single crystals of lower-mantle minerals.The developed LVP techniques presented here could enable the exploration of the chemical and physical properties of novel materials and Earth’s interior.展开更多
This study deals with the development of a 780-MPa-class hot-rolled advanced high-strength steel(AHSS)with an ultrahigh elongation at break of approximately 30%and strength-ductility product exceeding 24 GPa·%,in...This study deals with the development of a 780-MPa-class hot-rolled advanced high-strength steel(AHSS)with an ultrahigh elongation at break of approximately 30%and strength-ductility product exceeding 24 GPa·%,indicating the excellent formability of the newly developed AHSS.The microstructure of the newly developed 780-MPa-class AHSS consists mainly of the triplex phase of ferrite,bainite,and retained austenite with a volume fraction of 10%±2%.The stability of the retained austenite in the newly developed AHSS is much higher than that of conventional transformation-induced plasticity steels,in which the retained austenite is prone to transformation into martensite under deformation.At a pre-strain lower than 1.2%,the volume fraction of the retained austenite and the elongation at break of the present 780-MPa-class AHSS remain almost unchanged,showing a high tolerance in the process window during leveling or straightening.Therefore,the present 780-MPa-class AHSS is particularly suitable for the production of components with complex shapes.展开更多
The current generation of ultrahigh temperature ceramic precursors typically encounters obstacles in achieving high ceramic yields(<40 wt.%)due to the challenges in integrating significant amounts of boron,which ha...The current generation of ultrahigh temperature ceramic precursors typically encounters obstacles in achieving high ceramic yields(<40 wt.%)due to the challenges in integrating significant amounts of boron,which hampers their conversion into boride-based ultrahigh temperature ceramics.To tackle these challenges,a serious of pioneering liquid multi-component hafnium-containing ceramic SiHfCB precursors(with different Hf/Si ratios)have been developed.These novel precursors are featured with stable molec-ular structure and high ceramic yield which were successfully created through a novel one-pot polymer-ization process.They present in liquid form and their structure is characterized by C-C bonds forming its main chain with branched chains of O-Si-O,Si-O-Hf,Si-O-B,and B-O-Hf which have untapped advantages including uniform component dispersion,and excellent fluidity.The ceramic yield of SiHfCB precursor with Hf/Si of 0.2 is remarkably up to 68.6 wt.%at 1500℃,and their Hf content exceeded 50 wt.%.Of particular interest,the pyrolyzed product HfB_(2)-SiC nanopowders derived from the SiHfCB precursor with Hf/Si of 0.2,consist of nanopowders in the 40-60 nm range with a density of 5.23 g cm^(−3).Remarkably,this material demonstrates exceptional performance in ultrahigh temperature oxygen-containing environ-ments at 2500℃,showing near-zero ablation with a linear ablation rate of just 2.5×10^(−4) mm s^(−1).Post-ablation analysis of the microstructure reveals that the formation of a lava-like HfO_(2) and HfO_(2)-SiO_(2) oxide layer effectively blocks oxygen penetration and provides excellent oxidation resistance.The inno-vative SiHfCB hafnium-containing ceramic precursor offers a groundbreaking solution for the preparation of lightweight ultrahigh-temperature ceramics.This development is poised to provide robust technical support for the use of ultrahigh temperature ceramics in non-ablative thermal protective systems,partic-ularly in the construction of hypersonic vehicles,where ultrahigh temperature resilience is crucial.展开更多
Mg-1.2Y-1.2Ni(at.%)alloy was extruded at 400℃with an extrusion ratio of 16:1 and different rates from 1 to 6 mm/s.The effect of extrusion rate on microstructure and mechanical properties of the Mg-1.2Y-1.2Ni alloy wa...Mg-1.2Y-1.2Ni(at.%)alloy was extruded at 400℃with an extrusion ratio of 16:1 and different rates from 1 to 6 mm/s.The effect of extrusion rate on microstructure and mechanical properties of the Mg-1.2Y-1.2Ni alloy was systematically investigated.With the increase of extrusion rate,the average recrystallized grain size of Mg-1.2Y-1.2Ni alloy and mean particle diameter of Mg2Ni phase were increased,while the density of geometrically necessary dislocation and the intensity of the basal texture were decreased.When extrusion rate increases from 1 to 6 mm/s,the tensile yield strength(TYS)of asextruded Mg-1.2Y-1.2Ni alloy decreases from 501 to 281 MPa,while the elongation to failure increases from 1.5%to 6.2%.The Mg-1.2Y-1.2Ni alloy extruded at 3 mm/s obtained TYS of 421 MPa,the ultimate tensile strength(UTS)of 440 MPa and elongation to failure of 2.6%,respectively,exhibiting comprehensive mechanical properties with relatively good plasticity and ultrahigh strength.The ultrahigh TYS of 501 and 421 MPa was mainly due to the strengthening from ultrafine recrystallized grains,high volume fraction long period stacking ordered(LPSO)phases and high density dislocations.展开更多
In this study we theoretically demonstrate ultrahigh-resolution two-dimensional atomic localization within a three-levelλ-type atomic medium via superposition of asymmetric and symmetric standing wave fields.Our anal...In this study we theoretically demonstrate ultrahigh-resolution two-dimensional atomic localization within a three-levelλ-type atomic medium via superposition of asymmetric and symmetric standing wave fields.Our analysis provides an understanding of the precise spatial localization of atomic positions at the atomic level,utilizing advanced theoretical approaches and principles of quantum mechanics.The dynamical behavior of a three-level atomic system is thoroughly analyzed using the density matrix formalism within the realm of quantum mechanics.A theoretical approach is constructed to describe the interaction between the system and external fields,specifically a control field and a probe field.The absorption spectrum of the probe field is thoroughly examined to clarify the spatial localization of the atom within the proposed configuration.A theoretical investigation found that symmetric and asymmetric superposition phenomena significantly influence the localized peaks within a two-dimensional spatial domain.Specifically,the emergence of one and two sharp localized peaks was observed within a one-wavelength domain.We observed notable influences of the intensity of the control field,probe field detuning and decay rates on atomic localization.Ultimately,we have achieved an unprecedented level of ultrahigh resolution and precision in localizing an atom within an area smaller thanλ/35×λ/35.These findings hold promise for potential applications in fields such as Bose-Einstein condensation,nanolithography,laser cooling,trapping of neutral atoms and the measurement of center-of-mass wave functions.展开更多
To investigate the effects of the spraying process and different fibers on the mechanical properties and failure patterns of ultrahigh performance concrete(UHPC),three types of fibers were used.These fibers were forme...To investigate the effects of the spraying process and different fibers on the mechanical properties and failure patterns of ultrahigh performance concrete(UHPC),three types of fibers were used.These fibers were formed using both spraying and molding methods.Uniaxial compression tests were conducted,and two nondestructive monitoring techniques,acoustic emission(AE)and digital image correlation,were employed to monitor the uniaxial compression tests.The results indicated that the compressive strength of UHPC with single steel fibers and hybrid fibers increased by about 19%and 14%compared with those of UHPC with polyoxymethylene fibers.In comparison with molded UHPC,sprayed UHPC showed a slight improvement in compressive strength.Specimens containing steel fibers exhibited better post-cracking ductility,whereas those with only polyoxymethylene fibers displayed a certain degree of brittle failure.In sprayed UHPC,the onset of significant internal damage was delayed,which was related to the redistribution of internal fibers.The failure of UHPC was characterized by primary tensile cracks,supplemented by shear cracks.The spraying process can better restrict the development of tensile cracks in UHPC.Sprayed UHPC typically exhibited multiple crack developments leading to failure,whereas molded UHPC generally failed in the form of a single main crack penetrating the specimen.The addition of steel fibers delayed the occurrence of local stress concentration zones,aligning well with AE monitoring data.展开更多
High-loading Pt/C catalysts play an important role in the fabrication of membrane electrode assemblies with thin catalytic layer,which enhance mass transport and maintain the balance of water and heat.Unfortunately,as...High-loading Pt/C catalysts play an important role in the fabrication of membrane electrode assemblies with thin catalytic layer,which enhance mass transport and maintain the balance of water and heat.Unfortunately,as the loading increases,the agglomeration and growth of Pt nanoparticles(NPs)occur,causing unsatisfactory performance.Here,we present an efficient method for preparing of highly dispersed and small-sized Pt/C catalysts with Pt loadings varying from 39.01 wt%to 66.48 wt%through the high-temperature shock technique.The high density and ultrafine(~2.5 nm)Pt NPs are successfully anchored onto Vulcan XC-72R carbon black without the use of additional capping agents or surfactants.The modified carbon supports enhance the affinity for Pt precursors,contributing to loading efficiencies of 95%or more,while also providing abundant sites for the nucleation and fixation of Pt NPs,thus preventing agglomeration.In the context of the hydrogen evolution reaction in acidic media,the as-synthesized high-loading Pt/C catalysts show remarkable activity and stability,outperforming the state-of-the-art commercial Pt/C.This is mainly because the combined effects of ultrasmall and uniform Pt NPs,optimized electronic structure of Pt site,superhydrophilicity and effective anchoring of Pt NPs.The polymer electrolyte membrane electrolyzer integrated with Pt60/OX72R and commercial IrO2 reaches 1 A cm^(-2)at 1.77 V and operates stably for 120 hours with a negligible voltage decay.This new strategy is fast,scalable and cost-effective for large-scale production of metal-supported catalysts,especially for the high-loading ones.展开更多
To satisfy the demand for low-cost and long-range electric vehicles by the market,the commercialization of ultrahigh nickel cathode materials with high specific capacity and a wide electrochemical window is expected t...To satisfy the demand for low-cost and long-range electric vehicles by the market,the commercialization of ultrahigh nickel cathode materials with high specific capacity and a wide electrochemical window is expected to facilitate the development of lithium-ion batteries.However,residual lithium compounds with a strong alkalinity cause difficulty in cathode preparation and indirectly affect the cycling stability of the cathode during cycling.Given the inevitability of the formation of residual alkali,a lithium-borate coating with an adjustable thickness was selected by controlling the formation of residual alkali.An additional lithium source was added to the synthesis process and converted into a thicker and more complete coating structure,which rendered the cathode with better cycle stability.As a res-ult,the percentage of peak area of lithium carbonate on the surface-modified cathode surface exhibited a considerable decrease from 38.07%to 28.26%.The etching results show the formation of a uniform coating layer after boric acid treatment.The initial capacity of the treated cathode was 214.6 mAh·g^(-1) owing to the favorable effect of the surface coating,and the capacity retention raised from 59.35%to 90.75%and from 63.81%to 91.94%after cycling at 0.5 and 1 C current densities,respectively.The boric acid coating-modified strategy proposed in this paper considerably ameliorates the cycling stabilization of cathodes and provides superior commercial application value for ultrahigh nickel cathode materials.展开更多
This paper investigates interfacial heat transfer characteristics in amulti-layer structure under ultra-high heat flux conditions,focusing on thermal contact resistance(TCR)between adjacent layers.Athree-layer computa...This paper investigates interfacial heat transfer characteristics in amulti-layer structure under ultra-high heat flux conditions,focusing on thermal contact resistance(TCR)between adjacent layers.Athree-layer computational model with dual rough interfaces was developed to systematically analyze the synergistic effects of interfacial pressure,surface emissivity,and thermal interface materials(TIMs).Surface reconstruction using experimental measurement data generated two representative roughness models to quantify the impact of surface roughness on heat dissipation.Numerical simulations demonstrate that the absence of TIMs leads to insufficient thermal dissipation capacity under ultra-high heat flux conditions.Compared to TIMapplication,merely increasing the convective heat transfer coefficient shows limited effectiveness in enhancing heat dissipation efficiency.展开更多
1.Introduction The synthesis of bulk nanostructured multiphase(NM)mate-rials with extreme properties such as high hardness and strength is one of the most interesting research topics in materials science and engineeri...1.Introduction The synthesis of bulk nanostructured multiphase(NM)mate-rials with extreme properties such as high hardness and strength is one of the most interesting research topics in materials science and engineering[1].At present,NM alloys can be produced by several synthesis methods,including sintering of nanocomposites[2,3],physical or chemical vapour deposition(PVD or CVD)[4],crystallization of metallic glasses[5],and severe plastic deforma-tion(SPD)[6-8].However,industry applications of bulk NM alloys produced by these methods are significantly restricted by their ge-ometrical and size limitations.Thus,the fabrication of large-scale NM alloys remains challenging.展开更多
Innovative use of HfO_(2)-based high-dielectric-permittivity materials could enable their integration into few-nanometre-scale devices for storing substantial quantities of electrical charges,which have received wides...Innovative use of HfO_(2)-based high-dielectric-permittivity materials could enable their integration into few-nanometre-scale devices for storing substantial quantities of electrical charges,which have received widespread applications in high-storage-density dynamic random access memory and energy-efficient complementary metal-oxide-semiconductor devices.During bipolar high electric-field cycling in numbers close to dielectric breakdown,the dielectric permittivity suddenly increases by 30 times after oxygen-vacancy ordering and ferroelectric-to-nonferroelectric phase transition of near-edge plasma-treated Hf_(0.5)Zr_(0.5)O_(2) thin-film capacitors.Here we report a much higher dielectric permittivity of 1466 during downscaling of the capacitor into the diameter of 3.85μm when the ferroelectricity suddenly disappears without high-field cycling.The stored charge density is as high as 183μC cm^(−2) at an operating voltage/time of 1.2 V/50 ns at cycle numbers of more than 10^(12) without inducing dielectric breakdown.The study of synchrotron X-ray micro-diffraction patterns show missing of a mixed tetragonal phase.The image of electron energy loss spectroscopy shows the preferred oxygen-vacancy accumulation at the regions near top/bottom electrodes as well as grain boundaries.The ultrahigh dielectric-permittivity material enables high-density integration of extremely scaled logic and memory devices in the future.展开更多
This paper presents our endeavors in developing the large-scale, ultra-high-resolution E3SM Land Model (uELM), specifically designed for exascale computers furnished with accelerators such as Nvidia GPUs. The uELM is ...This paper presents our endeavors in developing the large-scale, ultra-high-resolution E3SM Land Model (uELM), specifically designed for exascale computers furnished with accelerators such as Nvidia GPUs. The uELM is a sophisticated code that substantially relies on High-Performance Computing (HPC) environments, necessitating particular machine and software configurations. To facilitate community-based uELM developments employing GPUs, we have created a portable, standalone software environment preconfigured with uELM input datasets, simulation cases, and source code. This environment, utilizing Docker, encompasses all essential code, libraries, and system software for uELM development on GPUs. It also features a functional unit test framework and an offline model testbed for comprehensive numerical experiments. From a technical perspective, the paper discusses GPU-ready container generations, uELM code management, and input data distribution across computational platforms. Lastly, the paper demonstrates the use of environment for functional unit testing, end-to-end simulation on CPUs and GPUs, and collaborative code development.展开更多
Herein,ionomer-free amorphous iridium oxide(IrO_(x))thin electrodes are first developed as highly active anodes for proton exchange membrane electrolyzer cells(PEMECs)via low-cost,environmentally friendly,and easily s...Herein,ionomer-free amorphous iridium oxide(IrO_(x))thin electrodes are first developed as highly active anodes for proton exchange membrane electrolyzer cells(PEMECs)via low-cost,environmentally friendly,and easily scalable electrodeposition at room temperature.Combined with a Nafion 117 membrane,the IrO_(x)-integrated electrode with an ultralow loading of 0.075 mg cm^(-2)delivers a high cell efficiency of about 90%,achieving more than 96%catalyst savings and 42-fold higher catalyst utilization compared to commercial catalyst-coated membrane(2 mg cm^(-2)).Additionally,the IrO_(x)electrode demonstrates superior performance,higher catalyst utilization and significantly simplified fabrication with easy scalability compared with the most previously reported anodes.Notably,the remarkable performance could be mainly due to the amorphous phase property,sufficient Ir^(3+)content,and rich surface hydroxide groups in catalysts.Overall,due to the high activity,high cell efficiency,an economical,greatly simplified and easily scalable fabrication process,and ultrahigh material utilization,the IrO_(x)electrode shows great potential to be applied in industry and accelerates the commercialization of PEMECs and renewable energy evolution.展开更多
Nanoprecipitates and nanoscale retained austenite(RA)with suitable stability play crucial roles in deter-mining the yield strength(YS)and ductility of ultrahigh strength steels(UHSSs).However,owing to the kinetics inc...Nanoprecipitates and nanoscale retained austenite(RA)with suitable stability play crucial roles in deter-mining the yield strength(YS)and ductility of ultrahigh strength steels(UHSSs).However,owing to the kinetics incompatibility between nanoprecipitation and austenite reversion,it is highly challenging to si-multaneously introduce high-density nanoprecipitates and optimized RA in UHSSs.In this work,through the combination of austenite reversion treatment(ART)and subsequent flash austenitizing(FA),nanoscale chemical heterogeneity was successfully introduced into a low-cost UHSS prior to the aging process.This chemical heterogeneity involved the enrichment of Mn and Ni in the austenite phase.The resulting UHSS exhibited dual-nanoprecipitation of Ni(Al,Mn)and(Mo,Cr)_(2)C and nanoscale austenite stabilized via Mn and Ni enrichment.The hard martensitic matrix strengthened by high-density dual-nanoprecipitates con-strains the plastic deformation of soft RA with a relatively low fraction of-15%,and the presence of relatively stable nanoscale RA with adequate Mn and Ni enrichment leads to a marginal loss in YS but keeps a persistent transformation-induced plasticity(TRIP)effect.As a result,the newly-developed UHSS exhibits an ultrahigh YS of-1.7 GPa,an ultimate tensile strength(UTS)of-1.8 GPa,a large uniform elongation(UE)of-8.5%,and a total elongation(TE)of-13%.The strategy of presetting chemical heterogeneity to introduce proper metastable phases before aging can be extended to other UHSSs and precipitation-hardened alloys.展开更多
Currently,more than ten ultrahigh arch dams have been constructed or are being constructed in China.Safety control is essential to long-term operation of these dams.This study employed the flexibility coefficient and ...Currently,more than ten ultrahigh arch dams have been constructed or are being constructed in China.Safety control is essential to long-term operation of these dams.This study employed the flexibility coefficient and plastic complementary energy norm to assess the structural safety of arch dams.A comprehensive analysis was conducted,focusing on differences among conventional methods in characterizing the structural behavior of the Xiaowan arch dam in China.Subsequently,the spatiotemporal characteristics of the measured performance of the Xiaowan dam were explored,including periodicity,convergence,and time-effect characteristics.These findings revealed the governing mechanism of main factors.Furthermore,a heterogeneous spatial panel vector model was developed,considering both common factors and specific factors affecting the safety and performance of arch dams.This model aims to comprehensively illustrate spatial heterogeneity between the entire structure and local regions,introducing a specific effect quantity to characterize local deformation differences.Ultimately,the proposed model was applied to the Xiaowan arch dam,accurately quantifying the spatiotemporal heterogeneity of dam performance.Additionally,the spatiotemporal distri-bution characteristics of environmental load effects on different parts of the dam were reasonably interpreted.Validation of the model prediction enhances its credibility,leading to the formulation of health diagnosis criteria for future long-term operation of the Xiaowan dam.The findings not only enhance the predictive ability and timely control of ultrahigh arch dams'performance but also provide a crucial basis for assessing the effectiveness of engineering treatment measures.展开更多
Ultrahigh-temperature-pressure experiments are crucial for understanding the physical and chemical properties of matter.The recent development of boron-doped diamond(BDD)heaters has made such melting experiments possi...Ultrahigh-temperature-pressure experiments are crucial for understanding the physical and chemical properties of matter.The recent development of boron-doped diamond(BDD)heaters has made such melting experiments possible in large-volume presses.However,estimates of temperatures above 2600 K and of the temperature distributions inside BDD heaters are not well constrained,owing to the lack of a suitable thermometer.Here,we establish a three-dimensional finite element model as a virtual thermometer to estimate the temperature and temperature field above 2600 K.The advantage of this virtual thermometer over those proposed in previous studies is that it considers both alternating and direct current heating modes,the actual sizes of cell assemblies after compression,the effects of the electrode,thermocouple and anvil,and the heat dissipation by the pressure-transmitting medium.The virtual thermometer reproduces the power-temperature relationships of ultrahigh-temperature-pressure experiments below 2600 K at press loads of 2.8-7.9 MN(~19 to 28 GPa)within experimental uncertainties.The temperatures above 2600 K predicted by our virtual thermometer are within the uncertainty of those extrapolated from power-temperature relationships below 2600 K.Furthermore,our model shows that the temperature distribution inside a BDD heater(19-26 K/mm along the radial direction and<83 K/mm along the longitudinal direction)is more homogeneous than those inside conventional heaters such as graphite or LaCrO_(3) heaters(100-200 K/mm).Our study thus provides a reliable virtual thermometer for ultrahigh-temperature experiments using BDD heaters in Earth and material sciences.展开更多
Drug loading capacity is very important in the construction of targeted drug delivery systems(TDDSs)for the improvement of drug delivery efficiency.However,the drug-loading capacity of most nanomaterials is non-ideali...Drug loading capacity is very important in the construction of targeted drug delivery systems(TDDSs)for the improvement of drug delivery efficiency.However,the drug-loading capacity of most nanomaterials is non-idealistic,and developing the high drug-loading TDDSs is still a critical challenge.In this work,an ultrahigh loading system(denoted as HMPB_(2))was prepared via J-aggregation of an aza-boron dipyrromethene derivative(Bod)by using hollow MnO_(2)modified with glucosamine pillar[5]arene as a carrier,which was demonstrated to have typical J-aggregate absorption of Bod,specific cancer cells targeting ability,negligible dark cytotoxicity,and potent phototoxicity.This work provides a successful example to construct an ultrahigh drug-loading system via J-aggregation for targeted delivery.展开更多
Zn-Li alloys are considered promising candidate materials for biodegradable orthopedic implant applications due to their high mechanical performance and good biocompatibility.However,the presence of a large number of ...Zn-Li alloys are considered promising candidate materials for biodegradable orthopedic implant applications due to their high mechanical performance and good biocompatibility.However,the presence of a large number of second-phase particles in this class of Zn alloys can lead to severe localized degradation due to micro-galvanic corrosion,which is detrimental to the mechanical integrity of the alloys during tissue healing in the human body.In this study we report ultrahigh strength,uniform corrosion,good cytocompatibility,and effective antibacterial ability in Zn-x Li(x=0.3,0.5,0.7;wt%)alloys achieved through supersaturated solid solution treatment(SSST)at 375℃ under ultrahigh pressure of 3 GPa.A high concentration of β-LiZn_(4)phases coexisted with the-Zn matrix in the as-cast Zn-x Li alloys,whereas almost all the Li dissolved into the-Zn matrix of SSST counterparts.The yield strength was 437 MPa for SSST Zn-0.3Li,592 MPa for SSST Zn-0.5 Li and 686 MPa for SSST Zn-0.7Li.The SSST Zn-Li alloys showed uniform degradation with remarkably reduced degradation rates compared to their as-cast counterparts.The 25% concentration extracts of the Zn-x Li alloys demonstrated no cytotoxicity toward MC3T3-E1 cells,and the alloys exhibited effective antibacterial ability agains methicillin-resistant staphylococcus aureus.展开更多
基金supported by the National Key R&D Program of China(Grant No.2023YFA1406200)the National Natural Science Foundation of China(Grant Nos.42272041 and 52302043)+2 种基金the National Natural Science Foundation of China(Grant No.U23A20561)the Jilin University High-level Innovation Team Foundation(Grant No.2021TD–05)the Shanghai Synchrotron Radiation Facility(Grant Nos.2024-SSRF-PT-510031 and 505511).
文摘The ability to generate high pressures in a large-volume press(LVP)is crucial for the study of matter under extreme conditions.Here,we have achieved ultrahigh pressures of and 50 GPa,respectively,at room temperature and a high temperature of 1900 K∼60within a millimeter-sized sample volume in a Kawai-type LVP(KLVP)using hard tungsten carbide(WC)and newly designed assem-blies.The introduction of electroconductive polycrystalline boron-doped diamond and dense alumina wrapped with Cu foils into a large conventional cell assembly enables the detection of resistance variations in the Fe_(2)O_(3) pressure standard upon compression.The efficiency of pressure generation in the newly developed cell assembly equipped with conventional ZK10F WC anvils is significantly higher than that of conventional assemblies with some ultrahard or tapered WC anvils.Our study has enabled the routine gener-ation of pressures exceeding 50 GPa within a millimeter-sized sample chamber that have been inaccessible with traditional KLVPs.This advance in high-pressure technology not only breaks a record for pressure generation in traditional KLVPs,but also opens up new avenues for exploration of the properties of the Earth’s deep interior and for the synthesis of novel materials at extreme high pressures.
基金supported by the National Key Research and Development Project(No.2023YFA1600082)the National Natural Science Foundation of China(Nos.U2141207,52001083,52171111)+3 种基金Natural Science Foundation of Heilongjiang(No.YQ2023E026)the Fundamental Research Funds for the Central Universities(No.3072022JIP1002)Key Laboratory Found of the Ministry of Industry and Information Technology(No.GXB202201)Youth Talent Project of China National Nuclear Corporation(No.CNNC2021YTEP-HEU01).
文摘How to achieve high-entropy alloys(HEAs)with ultrahigh strength and ductility is a challenging issue.Precipitation strengthening is one of the methods to significantly enhance strength,but unfortunately,ductility will be lost.To overcome the strength-ductility trade-off,the strategy of this study is to induce the formation of high-density nanoprecipitates through dual aging(DA),triggering multiple deformation mechanisms,to obtain HEAs with ultrahigh strength and ductility.First,the effect of precold deformation on precipitation behavior was studied using Ni_(35)(CoFe)_(55)V_(5)Nb_(5)(at.%)HEAas the object.The results reveal that the activation energy of recrystallization is 112.2 kJ/mol.As the precold-deformation amount increases from 15%to 65%,the activation energy of precipitation gradually decreases from 178.8 to 159.7 kJ/mol.The precipitation time shortens,the size of the nanoprecipitate decreases,and the density increases.Subsequently,the thermal treatment parameters were optimized,and the DA process was customized based on the effect of precold deformation on precipitation behavior.High-density L1_(2) nanoprecipitates(~3.21×10^(25) m^(-3))were induced in the 65% precold-deformed HEA,which led to the simultaneous formation of twins and stacking fault(SF)networks during deformation.The yield strength(YS),ultimate tensile strength,and ductility of the DA-HEA are~2.0 GPa,~2.2 GPa,and~12.3%,respectively.Compared with the solid solution HEA,the YS of the DA-HEA increased by 1,657 MPa,possessing an astonishing increase of~440%.The high YS stems from the precipitation strengthening contributed by the L1_(2) nanoprecipitates and the dislocation strengthening contributed by precold deformation.The synergistically enhanced ductility stems from the high strain-hardening ability under the dual support of twinning-induced plasticity and SF-induced plasticity.
基金supported by the National Key Research and Development Program of China(2022YFB3706600 and 2023YFA1406200)the National Natural Science Founda-tion of China(42272041,52302043,12304015,41902034,and 12011530063)+1 种基金the Jilin University High-level Innovation Team Foundation,China(2021TD-05)the National Major Science Facility Synergetic Extreme Condition User Facility Achievement Transformation Platform Construction(2021FGWCXNLJSKJ01).
文摘Ultrahigh pressure generation at high temperatures is technologically challenging for large sample volumes.In this study,we successfully generated pressures of 37.3-40.4 GPa at 1900-2100 K in a Walker-type large-volume press(LVP).Expansion of the pressure range at high temperatures was achieved by adapting newly designed ZK01F tungsten carbide(WC)anvils with tapered surfaces and using cell assemblies with an^(-1) mm^(3) sample volume and hard materials,as well as by applying certain adjustments to the apparatus.The pressure efficiencies of the different types of WC anvils and cell assemblies were also studied.Using the above-mentioned techniques,we successfully synthesized and characterized bulk samples of nearly pure sp3-hybridized ultrahard amorphous carbon,core-shell nanocrystals with high Néel temperatures,as well as large-sized single crystals of lower-mantle minerals.The developed LVP techniques presented here could enable the exploration of the chemical and physical properties of novel materials and Earth’s interior.
文摘This study deals with the development of a 780-MPa-class hot-rolled advanced high-strength steel(AHSS)with an ultrahigh elongation at break of approximately 30%and strength-ductility product exceeding 24 GPa·%,indicating the excellent formability of the newly developed AHSS.The microstructure of the newly developed 780-MPa-class AHSS consists mainly of the triplex phase of ferrite,bainite,and retained austenite with a volume fraction of 10%±2%.The stability of the retained austenite in the newly developed AHSS is much higher than that of conventional transformation-induced plasticity steels,in which the retained austenite is prone to transformation into martensite under deformation.At a pre-strain lower than 1.2%,the volume fraction of the retained austenite and the elongation at break of the present 780-MPa-class AHSS remain almost unchanged,showing a high tolerance in the process window during leveling or straightening.Therefore,the present 780-MPa-class AHSS is particularly suitable for the production of components with complex shapes.
基金supported by the Key Program of the National Natural Science Foundation of China(No.52032003)the Major Program of the National Natural Science Foundation of China(No.52293372)+2 种基金the National Natural Science Foundation of China(No.51972082)the National Natural Science Foundation of China(No.52102093)the National Natural Science Foundation of China(No.52172041)and the science foundation of national key laboratory of science and technology on advanced composites in special environments.
文摘The current generation of ultrahigh temperature ceramic precursors typically encounters obstacles in achieving high ceramic yields(<40 wt.%)due to the challenges in integrating significant amounts of boron,which hampers their conversion into boride-based ultrahigh temperature ceramics.To tackle these challenges,a serious of pioneering liquid multi-component hafnium-containing ceramic SiHfCB precursors(with different Hf/Si ratios)have been developed.These novel precursors are featured with stable molec-ular structure and high ceramic yield which were successfully created through a novel one-pot polymer-ization process.They present in liquid form and their structure is characterized by C-C bonds forming its main chain with branched chains of O-Si-O,Si-O-Hf,Si-O-B,and B-O-Hf which have untapped advantages including uniform component dispersion,and excellent fluidity.The ceramic yield of SiHfCB precursor with Hf/Si of 0.2 is remarkably up to 68.6 wt.%at 1500℃,and their Hf content exceeded 50 wt.%.Of particular interest,the pyrolyzed product HfB_(2)-SiC nanopowders derived from the SiHfCB precursor with Hf/Si of 0.2,consist of nanopowders in the 40-60 nm range with a density of 5.23 g cm^(−3).Remarkably,this material demonstrates exceptional performance in ultrahigh temperature oxygen-containing environ-ments at 2500℃,showing near-zero ablation with a linear ablation rate of just 2.5×10^(−4) mm s^(−1).Post-ablation analysis of the microstructure reveals that the formation of a lava-like HfO_(2) and HfO_(2)-SiO_(2) oxide layer effectively blocks oxygen penetration and provides excellent oxidation resistance.The inno-vative SiHfCB hafnium-containing ceramic precursor offers a groundbreaking solution for the preparation of lightweight ultrahigh-temperature ceramics.This development is poised to provide robust technical support for the use of ultrahigh temperature ceramics in non-ablative thermal protective systems,partic-ularly in the construction of hypersonic vehicles,where ultrahigh temperature resilience is crucial.
基金the financial support from the National Natural Science Foundation of China(No.12164004)the Jiangxi Provincial Natural Science Foundation(Nos.20242BAB25210,20232BCJ25067,20232BAB214004 and 20224BAB204029)+2 种基金the Foundation of Education Department of Jiangxi Provincial(Nos.GJJ2201247 and GJJ211436)the Young and Middle-aged Teachers Education Scientific Research Project of Fujian Province(No.JAT231008)supported by Sinoma Institute of Materials Research(Guang Zhou)Co.,Ltd(SIMR).
文摘Mg-1.2Y-1.2Ni(at.%)alloy was extruded at 400℃with an extrusion ratio of 16:1 and different rates from 1 to 6 mm/s.The effect of extrusion rate on microstructure and mechanical properties of the Mg-1.2Y-1.2Ni alloy was systematically investigated.With the increase of extrusion rate,the average recrystallized grain size of Mg-1.2Y-1.2Ni alloy and mean particle diameter of Mg2Ni phase were increased,while the density of geometrically necessary dislocation and the intensity of the basal texture were decreased.When extrusion rate increases from 1 to 6 mm/s,the tensile yield strength(TYS)of asextruded Mg-1.2Y-1.2Ni alloy decreases from 501 to 281 MPa,while the elongation to failure increases from 1.5%to 6.2%.The Mg-1.2Y-1.2Ni alloy extruded at 3 mm/s obtained TYS of 421 MPa,the ultimate tensile strength(UTS)of 440 MPa and elongation to failure of 2.6%,respectively,exhibiting comprehensive mechanical properties with relatively good plasticity and ultrahigh strength.The ultrahigh TYS of 501 and 421 MPa was mainly due to the strengthening from ultrafine recrystallized grains,high volume fraction long period stacking ordered(LPSO)phases and high density dislocations.
文摘In this study we theoretically demonstrate ultrahigh-resolution two-dimensional atomic localization within a three-levelλ-type atomic medium via superposition of asymmetric and symmetric standing wave fields.Our analysis provides an understanding of the precise spatial localization of atomic positions at the atomic level,utilizing advanced theoretical approaches and principles of quantum mechanics.The dynamical behavior of a three-level atomic system is thoroughly analyzed using the density matrix formalism within the realm of quantum mechanics.A theoretical approach is constructed to describe the interaction between the system and external fields,specifically a control field and a probe field.The absorption spectrum of the probe field is thoroughly examined to clarify the spatial localization of the atom within the proposed configuration.A theoretical investigation found that symmetric and asymmetric superposition phenomena significantly influence the localized peaks within a two-dimensional spatial domain.Specifically,the emergence of one and two sharp localized peaks was observed within a one-wavelength domain.We observed notable influences of the intensity of the control field,probe field detuning and decay rates on atomic localization.Ultimately,we have achieved an unprecedented level of ultrahigh resolution and precision in localizing an atom within an area smaller thanλ/35×λ/35.These findings hold promise for potential applications in fields such as Bose-Einstein condensation,nanolithography,laser cooling,trapping of neutral atoms and the measurement of center-of-mass wave functions.
基金The National Natural Science Foundation of China(No.52379124)the National Key Research and Development Program of China(No.2021YFB2600200).
文摘To investigate the effects of the spraying process and different fibers on the mechanical properties and failure patterns of ultrahigh performance concrete(UHPC),three types of fibers were used.These fibers were formed using both spraying and molding methods.Uniaxial compression tests were conducted,and two nondestructive monitoring techniques,acoustic emission(AE)and digital image correlation,were employed to monitor the uniaxial compression tests.The results indicated that the compressive strength of UHPC with single steel fibers and hybrid fibers increased by about 19%and 14%compared with those of UHPC with polyoxymethylene fibers.In comparison with molded UHPC,sprayed UHPC showed a slight improvement in compressive strength.Specimens containing steel fibers exhibited better post-cracking ductility,whereas those with only polyoxymethylene fibers displayed a certain degree of brittle failure.In sprayed UHPC,the onset of significant internal damage was delayed,which was related to the redistribution of internal fibers.The failure of UHPC was characterized by primary tensile cracks,supplemented by shear cracks.The spraying process can better restrict the development of tensile cracks in UHPC.Sprayed UHPC typically exhibited multiple crack developments leading to failure,whereas molded UHPC generally failed in the form of a single main crack penetrating the specimen.The addition of steel fibers delayed the occurrence of local stress concentration zones,aligning well with AE monitoring data.
文摘High-loading Pt/C catalysts play an important role in the fabrication of membrane electrode assemblies with thin catalytic layer,which enhance mass transport and maintain the balance of water and heat.Unfortunately,as the loading increases,the agglomeration and growth of Pt nanoparticles(NPs)occur,causing unsatisfactory performance.Here,we present an efficient method for preparing of highly dispersed and small-sized Pt/C catalysts with Pt loadings varying from 39.01 wt%to 66.48 wt%through the high-temperature shock technique.The high density and ultrafine(~2.5 nm)Pt NPs are successfully anchored onto Vulcan XC-72R carbon black without the use of additional capping agents or surfactants.The modified carbon supports enhance the affinity for Pt precursors,contributing to loading efficiencies of 95%or more,while also providing abundant sites for the nucleation and fixation of Pt NPs,thus preventing agglomeration.In the context of the hydrogen evolution reaction in acidic media,the as-synthesized high-loading Pt/C catalysts show remarkable activity and stability,outperforming the state-of-the-art commercial Pt/C.This is mainly because the combined effects of ultrasmall and uniform Pt NPs,optimized electronic structure of Pt site,superhydrophilicity and effective anchoring of Pt NPs.The polymer electrolyte membrane electrolyzer integrated with Pt60/OX72R and commercial IrO2 reaches 1 A cm^(-2)at 1.77 V and operates stably for 120 hours with a negligible voltage decay.This new strategy is fast,scalable and cost-effective for large-scale production of metal-supported catalysts,especially for the high-loading ones.
基金financially supported by the National Natural Science Foundation of China(Nos.52071073,52177208,and 52171202)the Hebei Province“333 talent project”,China(No.C20221012)+2 种基金the Science and Technology Project of Hebei Education Department,China(No.BJK2023005)the Fundamental Research Funds for the Central Universities(No.2024GFZD002)the Natural Science Foundation of Hebei Province,China(No.E2024501015).
文摘To satisfy the demand for low-cost and long-range electric vehicles by the market,the commercialization of ultrahigh nickel cathode materials with high specific capacity and a wide electrochemical window is expected to facilitate the development of lithium-ion batteries.However,residual lithium compounds with a strong alkalinity cause difficulty in cathode preparation and indirectly affect the cycling stability of the cathode during cycling.Given the inevitability of the formation of residual alkali,a lithium-borate coating with an adjustable thickness was selected by controlling the formation of residual alkali.An additional lithium source was added to the synthesis process and converted into a thicker and more complete coating structure,which rendered the cathode with better cycle stability.As a res-ult,the percentage of peak area of lithium carbonate on the surface-modified cathode surface exhibited a considerable decrease from 38.07%to 28.26%.The etching results show the formation of a uniform coating layer after boric acid treatment.The initial capacity of the treated cathode was 214.6 mAh·g^(-1) owing to the favorable effect of the surface coating,and the capacity retention raised from 59.35%to 90.75%and from 63.81%to 91.94%after cycling at 0.5 and 1 C current densities,respectively.The boric acid coating-modified strategy proposed in this paper considerably ameliorates the cycling stabilization of cathodes and provides superior commercial application value for ultrahigh nickel cathode materials.
基金by the Natural Science Foundation of Shandong Province,China(No.ZR2023QE159).
文摘This paper investigates interfacial heat transfer characteristics in amulti-layer structure under ultra-high heat flux conditions,focusing on thermal contact resistance(TCR)between adjacent layers.Athree-layer computational model with dual rough interfaces was developed to systematically analyze the synergistic effects of interfacial pressure,surface emissivity,and thermal interface materials(TIMs).Surface reconstruction using experimental measurement data generated two representative roughness models to quantify the impact of surface roughness on heat dissipation.Numerical simulations demonstrate that the absence of TIMs leads to insufficient thermal dissipation capacity under ultra-high heat flux conditions.Compared to TIMapplication,merely increasing the convective heat transfer coefficient shows limited effectiveness in enhancing heat dissipation efficiency.
基金funding from the Australian Research Council(ARC Discovery Project,Nos.DP200101408 and DP230100183).
文摘1.Introduction The synthesis of bulk nanostructured multiphase(NM)mate-rials with extreme properties such as high hardness and strength is one of the most interesting research topics in materials science and engineering[1].At present,NM alloys can be produced by several synthesis methods,including sintering of nanocomposites[2,3],physical or chemical vapour deposition(PVD or CVD)[4],crystallization of metallic glasses[5],and severe plastic deforma-tion(SPD)[6-8].However,industry applications of bulk NM alloys produced by these methods are significantly restricted by their ge-ometrical and size limitations.Thus,the fabrication of large-scale NM alloys remains challenging.
基金supported by the National Key Basic Research Program of China (2022YFA1402904)Basic Research Project of Shanghai Science and Technology Innovation Action (grant number 24CL2900900)the National Natural Science Foundation of China (grant number 61904034)
文摘Innovative use of HfO_(2)-based high-dielectric-permittivity materials could enable their integration into few-nanometre-scale devices for storing substantial quantities of electrical charges,which have received widespread applications in high-storage-density dynamic random access memory and energy-efficient complementary metal-oxide-semiconductor devices.During bipolar high electric-field cycling in numbers close to dielectric breakdown,the dielectric permittivity suddenly increases by 30 times after oxygen-vacancy ordering and ferroelectric-to-nonferroelectric phase transition of near-edge plasma-treated Hf_(0.5)Zr_(0.5)O_(2) thin-film capacitors.Here we report a much higher dielectric permittivity of 1466 during downscaling of the capacitor into the diameter of 3.85μm when the ferroelectricity suddenly disappears without high-field cycling.The stored charge density is as high as 183μC cm^(−2) at an operating voltage/time of 1.2 V/50 ns at cycle numbers of more than 10^(12) without inducing dielectric breakdown.The study of synchrotron X-ray micro-diffraction patterns show missing of a mixed tetragonal phase.The image of electron energy loss spectroscopy shows the preferred oxygen-vacancy accumulation at the regions near top/bottom electrodes as well as grain boundaries.The ultrahigh dielectric-permittivity material enables high-density integration of extremely scaled logic and memory devices in the future.
文摘This paper presents our endeavors in developing the large-scale, ultra-high-resolution E3SM Land Model (uELM), specifically designed for exascale computers furnished with accelerators such as Nvidia GPUs. The uELM is a sophisticated code that substantially relies on High-Performance Computing (HPC) environments, necessitating particular machine and software configurations. To facilitate community-based uELM developments employing GPUs, we have created a portable, standalone software environment preconfigured with uELM input datasets, simulation cases, and source code. This environment, utilizing Docker, encompasses all essential code, libraries, and system software for uELM development on GPUs. It also features a functional unit test framework and an offline model testbed for comprehensive numerical experiments. From a technical perspective, the paper discusses GPU-ready container generations, uELM code management, and input data distribution across computational platforms. Lastly, the paper demonstrates the use of environment for functional unit testing, end-to-end simulation on CPUs and GPUs, and collaborative code development.
基金the support from the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under the Hydrogen and Fuel Cell Technologies Office Awards DE-EE0008426 and DE-EE0008423National Energy Technology Laboratory under Award DEFE0011585.
文摘Herein,ionomer-free amorphous iridium oxide(IrO_(x))thin electrodes are first developed as highly active anodes for proton exchange membrane electrolyzer cells(PEMECs)via low-cost,environmentally friendly,and easily scalable electrodeposition at room temperature.Combined with a Nafion 117 membrane,the IrO_(x)-integrated electrode with an ultralow loading of 0.075 mg cm^(-2)delivers a high cell efficiency of about 90%,achieving more than 96%catalyst savings and 42-fold higher catalyst utilization compared to commercial catalyst-coated membrane(2 mg cm^(-2)).Additionally,the IrO_(x)electrode demonstrates superior performance,higher catalyst utilization and significantly simplified fabrication with easy scalability compared with the most previously reported anodes.Notably,the remarkable performance could be mainly due to the amorphous phase property,sufficient Ir^(3+)content,and rich surface hydroxide groups in catalysts.Overall,due to the high activity,high cell efficiency,an economical,greatly simplified and easily scalable fabrication process,and ultrahigh material utilization,the IrO_(x)electrode shows great potential to be applied in industry and accelerates the commercialization of PEMECs and renewable energy evolution.
基金Z.G.Yang acknowledges financial support from the National Key R&D program of China(grant No.2022YFB3705200)National Natural Science Foundation of China(grant No.52171008)+2 种基金H.Chen acknowledges financial support from the National Natural Science Foundation of China(grant No.51922054)Tsinghua University Initiative Scientific Research Program(No.20233080002)the Mobility Programme from the Sino-German Center(Grant No.M-0319).
文摘Nanoprecipitates and nanoscale retained austenite(RA)with suitable stability play crucial roles in deter-mining the yield strength(YS)and ductility of ultrahigh strength steels(UHSSs).However,owing to the kinetics incompatibility between nanoprecipitation and austenite reversion,it is highly challenging to si-multaneously introduce high-density nanoprecipitates and optimized RA in UHSSs.In this work,through the combination of austenite reversion treatment(ART)and subsequent flash austenitizing(FA),nanoscale chemical heterogeneity was successfully introduced into a low-cost UHSS prior to the aging process.This chemical heterogeneity involved the enrichment of Mn and Ni in the austenite phase.The resulting UHSS exhibited dual-nanoprecipitation of Ni(Al,Mn)and(Mo,Cr)_(2)C and nanoscale austenite stabilized via Mn and Ni enrichment.The hard martensitic matrix strengthened by high-density dual-nanoprecipitates con-strains the plastic deformation of soft RA with a relatively low fraction of-15%,and the presence of relatively stable nanoscale RA with adequate Mn and Ni enrichment leads to a marginal loss in YS but keeps a persistent transformation-induced plasticity(TRIP)effect.As a result,the newly-developed UHSS exhibits an ultrahigh YS of-1.7 GPa,an ultimate tensile strength(UTS)of-1.8 GPa,a large uniform elongation(UE)of-8.5%,and a total elongation(TE)of-13%.The strategy of presetting chemical heterogeneity to introduce proper metastable phases before aging can be extended to other UHSSs and precipitation-hardened alloys.
基金supported by the National Natural Science Foundation of China(Grant No.52079046).
文摘Currently,more than ten ultrahigh arch dams have been constructed or are being constructed in China.Safety control is essential to long-term operation of these dams.This study employed the flexibility coefficient and plastic complementary energy norm to assess the structural safety of arch dams.A comprehensive analysis was conducted,focusing on differences among conventional methods in characterizing the structural behavior of the Xiaowan arch dam in China.Subsequently,the spatiotemporal characteristics of the measured performance of the Xiaowan dam were explored,including periodicity,convergence,and time-effect characteristics.These findings revealed the governing mechanism of main factors.Furthermore,a heterogeneous spatial panel vector model was developed,considering both common factors and specific factors affecting the safety and performance of arch dams.This model aims to comprehensively illustrate spatial heterogeneity between the entire structure and local regions,introducing a specific effect quantity to characterize local deformation differences.Ultimately,the proposed model was applied to the Xiaowan arch dam,accurately quantifying the spatiotemporal heterogeneity of dam performance.Additionally,the spatiotemporal distri-bution characteristics of environmental load effects on different parts of the dam were reasonably interpreted.Validation of the model prediction enhances its credibility,leading to the formulation of health diagnosis criteria for future long-term operation of the Xiaowan dam.The findings not only enhance the predictive ability and timely control of ultrahigh arch dams'performance but also provide a crucial basis for assessing the effectiveness of engineering treatment measures.
基金supported financially by the National Key R&D Program of China(Grant No.2022YFB3706602)the National Natural Science Foundation of China(Grant Nos.42272041,41902034,and 12011530063)the Jilin University High-Level Innovation Team Foundation,China(Grant No.2021TD-05).
文摘Ultrahigh-temperature-pressure experiments are crucial for understanding the physical and chemical properties of matter.The recent development of boron-doped diamond(BDD)heaters has made such melting experiments possible in large-volume presses.However,estimates of temperatures above 2600 K and of the temperature distributions inside BDD heaters are not well constrained,owing to the lack of a suitable thermometer.Here,we establish a three-dimensional finite element model as a virtual thermometer to estimate the temperature and temperature field above 2600 K.The advantage of this virtual thermometer over those proposed in previous studies is that it considers both alternating and direct current heating modes,the actual sizes of cell assemblies after compression,the effects of the electrode,thermocouple and anvil,and the heat dissipation by the pressure-transmitting medium.The virtual thermometer reproduces the power-temperature relationships of ultrahigh-temperature-pressure experiments below 2600 K at press loads of 2.8-7.9 MN(~19 to 28 GPa)within experimental uncertainties.The temperatures above 2600 K predicted by our virtual thermometer are within the uncertainty of those extrapolated from power-temperature relationships below 2600 K.Furthermore,our model shows that the temperature distribution inside a BDD heater(19-26 K/mm along the radial direction and<83 K/mm along the longitudinal direction)is more homogeneous than those inside conventional heaters such as graphite or LaCrO_(3) heaters(100-200 K/mm).Our study thus provides a reliable virtual thermometer for ultrahigh-temperature experiments using BDD heaters in Earth and material sciences.
基金the National Natural Science Foundation of China(Nos.22171230 and 21877088)the Project of Science and Technology of Social Development in Shaanxi Province(No.2021SF-120)。
文摘Drug loading capacity is very important in the construction of targeted drug delivery systems(TDDSs)for the improvement of drug delivery efficiency.However,the drug-loading capacity of most nanomaterials is non-idealistic,and developing the high drug-loading TDDSs is still a critical challenge.In this work,an ultrahigh loading system(denoted as HMPB_(2))was prepared via J-aggregation of an aza-boron dipyrromethene derivative(Bod)by using hollow MnO_(2)modified with glucosamine pillar[5]arene as a carrier,which was demonstrated to have typical J-aggregate absorption of Bod,specific cancer cells targeting ability,negligible dark cytotoxicity,and potent phototoxicity.This work provides a successful example to construct an ultrahigh drug-loading system via J-aggregation for targeted delivery.
基金financially supported by Hunan Provincial Natural Science Foundation of China(No.2023JJ40626)the National Natural Science Foundation of China(Nos.11872053 and 51971190)+1 种基金the Post-graduate Scientific Research Innovation Project of Hunan Province(No.CX20210625)the Australian Research Council(ARC)through the Discovery Project(No.DP210101862)。
文摘Zn-Li alloys are considered promising candidate materials for biodegradable orthopedic implant applications due to their high mechanical performance and good biocompatibility.However,the presence of a large number of second-phase particles in this class of Zn alloys can lead to severe localized degradation due to micro-galvanic corrosion,which is detrimental to the mechanical integrity of the alloys during tissue healing in the human body.In this study we report ultrahigh strength,uniform corrosion,good cytocompatibility,and effective antibacterial ability in Zn-x Li(x=0.3,0.5,0.7;wt%)alloys achieved through supersaturated solid solution treatment(SSST)at 375℃ under ultrahigh pressure of 3 GPa.A high concentration of β-LiZn_(4)phases coexisted with the-Zn matrix in the as-cast Zn-x Li alloys,whereas almost all the Li dissolved into the-Zn matrix of SSST counterparts.The yield strength was 437 MPa for SSST Zn-0.3Li,592 MPa for SSST Zn-0.5 Li and 686 MPa for SSST Zn-0.7Li.The SSST Zn-Li alloys showed uniform degradation with remarkably reduced degradation rates compared to their as-cast counterparts.The 25% concentration extracts of the Zn-x Li alloys demonstrated no cytotoxicity toward MC3T3-E1 cells,and the alloys exhibited effective antibacterial ability agains methicillin-resistant staphylococcus aureus.
