Utilizing supported single atoms as catalysts presents an opportunity to reduce the usage of critical raw materials such as platinum,which are essential for electrochemical reactions such as hydrogen oxidation reactio...Utilizing supported single atoms as catalysts presents an opportunity to reduce the usage of critical raw materials such as platinum,which are essential for electrochemical reactions such as hydrogen oxidation reaction(HOR).Herein,we describe the synthesis of a Pt single electrocatalyst inside single-walled carbon nanotubes(SWCNTs)via a redox reaction.Characterizations via electron microscopy,X-ray photoelectron microscopy,and X-ray absorption spectroscopy show the single-atom nature of the Pt.The electrochemical behavior of the sample to hydrogen and oxygen was investigated using the advanced floating electrode technique,which minimizes mass transport limitations and gives a thorough insight into the activity of the electrocatalyst.The single-atom samples showed higher HOR activity than state-of-the-art 30%Pt/C while almost no oxygen reduction reaction activity in the proton exchange membrane fuel cell operating range.The selective activity toward HOR arose as the main fingerprint of the catalyst confinement in the SWCNTs.展开更多
Single-atom catalysts(SACs)have gained substantial attention because of their exceptional catalytic properties.However,the high surface energy limits their synthesis,thus creating significant challenges for further de...Single-atom catalysts(SACs)have gained substantial attention because of their exceptional catalytic properties.However,the high surface energy limits their synthesis,thus creating significant challenges for further development.In the last few years,metal–organic frameworks(MOFs)have received significant consideration as ideal candidates for synthesizing SACs due to their tailorable chemistry,tunable morphologies,high porosity,and chemical/thermal stability.From this perspective,this review thoroughly summarizes the previously reported methods and possible future approaches for constructing MOF-based(MOF-derived-supported and MOF-supported)SACs.Then,MOF-based SAC's identification techniques are briefly assessed to understand their coordination environments,local electronic structures,spatial distributions,and catalytic/electrochemical reaction mechanisms.This review systematically highlights several photocatalytic and electrocatalytic applications of MOF-based SACs for energy conversion and storage,including hydrogen evolution reactions,oxygen evolution reactions,O_(2)/CO_(2)/N_(2) reduction reactions,fuel cells,and rechargeable batteries.Some light is also shed on the future development of this highly exciting field by highlighting the advantages and limitations of MOF-based SACs.展开更多
Atom-level modulation of the coordination environment for single-atom catalysts(SACs)is considered as an effective strategy for elevating the catalytic performance.For the MNxsite,breaking the symmetrical geometry and...Atom-level modulation of the coordination environment for single-atom catalysts(SACs)is considered as an effective strategy for elevating the catalytic performance.For the MNxsite,breaking the symmetrical geometry and charge distribution by introducing relatively weak electronegative atoms into the first/second shell is an efficient way,but it remains challenging for elucidating the underlying mechanism of interaction.Herein,a practical strategy was reported to rationally design single cobalt atoms coordinated with both phosphorus and nitrogen atoms in a hierarchically porous carbon derived from metal-organic frameworks.X-ray absorption spectrum reveals that atomically dispersed Co sites are coordinated with four N atoms in the first shell and varying numbers of P atoms in the second shell(denoted as Co-N/P-C).The prepared catalyst exhibits excellent oxygen reduction reaction(ORR)activity as well as zinc-air battery performance.The introduction of P atoms in the Co-SACs weakens the interaction between Co and N,significantly promoting the adsorption process of ^(*)OOH,resulting in the acceleration of reaction kinetics and reduction of thermodynamic barrier,responsible for the increased intrinsic activity.Our discovery provides insights into an ultimate design of single-atom catalysts with adjustable electrocatalytic activities for efficient electrochemical energy conversion.展开更多
Single ventricle is an uncommon congenital cardiac pathology with high mortality at early ages. However, due to new strategies and timely surgical treatment, it is increasingly seen in adults, which has increased the ...Single ventricle is an uncommon congenital cardiac pathology with high mortality at early ages. However, due to new strategies and timely surgical treatment, it is increasingly seen in adults, which has increased the survival rate. This condition is characterized by a heart with a single functional ventricular cavity. The aim of this article is to report the case of a 40-year-old male with single ventricle, who underwent several surgeries in his childhood. After these surgical procedures, the patient lost medical follow-up and presented complications derived from the disease itself. Heart Failure is a common complication in people with single ventricle, and pharmacological heart failure therapies have been ineffective in mitigating the need of the heart transplantation. That’s why it is essential to develop and apply new pharmacological techniques for the management of these patients in childhood as well as in adulthood. This would allow not only to avoid various comorbidities, but also to improve the quality of life of the patients.展开更多
Background: World Health Organization recommends the implementation of contact tracing and Leprosy Post Exposure prophylaxis (LPEP) to interrupt the chain of transmission. To accelerate the uptake of this recommendati...Background: World Health Organization recommends the implementation of contact tracing and Leprosy Post Exposure prophylaxis (LPEP) to interrupt the chain of transmission. To accelerate the uptake of this recommendation, a cross-sectional study among contacts of leprosy patients was conducted to investigate the feasibility of integrating leprosy systematic contact tracing and post-exposure prophylaxis (PEP) into the routine leprosy control program. Methods: This was a mixed methods cross-sectional study. The study was implemented in Kumi, Ngora, Serere, Soroti, Budaka and Kibuku Districts. Results: The 45 enrolled index patients (97.8% of the registered) identified a total of 135 contacts, of which 134 (99·2%) consented and were screened. Among them, one new leprosy patient was identified and started on treatment with multidrug therapy (MDT). All the eligible contacts, received the prophylactic treatment with Single Dose Rifampicin (SDR). Overall, SDR was administered to 133(98.5% of the listed contacts) with no adverse event reported. Factors associated with successful contact investigation and management included: Involvement of index patients, health care workers during the contact screening and SDR A administration, counselling of the index patients and contacts by the health care works, LPEP being administered as Directly observed Therapy (DOT) among others. Results Interpretation: The integration of leprosy post-exposure prophylaxis with administration of SDR and contact tracing is feasible, generally accepted by the patient, their contacts and health workers and can be integrated into the National Leprosy control programmes with minimal additional efforts once contact tracing has been established. Therefore, we recommend integration of administration of SDR in to the routine leprosy control program.展开更多
Single-atom catalysts(SACs)are gaining popularity in catalytic reactions due to their nearly 100%atomic utilization and defined active sites,which provide great convenience for studying the catalytic mechanism of cata...Single-atom catalysts(SACs)are gaining popularity in catalytic reactions due to their nearly 100%atomic utilization and defined active sites,which provide great convenience for studying the catalytic mechanism of catalysts.However,SACs still present challenges such as complex formation processes,low loading and easy agglomeration of catalysts.Herein,we systematically discuss the synthesis methods for SACs,including coprecipitation,impregnation,atomic layer deposition,pyrolysis and Anti-Ostwald ripening etc.Various techniques for characterizing single-atom catalysts(SACs)are described in detail.The utilization of individual atoms in various photocatalytic reactions and their mechanisms of action in different reactions are explained.The purpose of this review is to introduce single-atom synthesis methods,characterization techniques,specific catalytic action and their applications in the direction of photocatalysis,and to provide a reference for the industrialization of photocatalytic single-atoms,which is currently impossible,in the hope of promoting further development of photocatalytic single-atoms.展开更多
The co-catalysis between single atom catalyst(SAC)and its support has recently emerged as a promising strategy to synergistically boost the catalytic activity of some complex electrochemical reactions,encompassing mul...The co-catalysis between single atom catalyst(SAC)and its support has recently emerged as a promising strategy to synergistically boost the catalytic activity of some complex electrochemical reactions,encompassing multiple intermediates and pathways.Herein,we utilized defective BC_(3)monolayer-supported SACs as a prototype to investigate the cooperative effects of SACs and their support on the catalytic performance of the nitrogen reduction reaction(NRR)for ammonia(NH_(3))production.The results showed that these SACs can be firmly stabilized on these defective BC_(3)supports with high stability against aggregation.Furthermore,co-activation of the inert N_(2)reactant was observed in certain embedded SACs and their neighboring B atoms on certain BC3 sheets due to the noticeable charge transfer and significant N–N bond elongation.Our high-throughput screening revealed that the Mo/DV_(CC)and W/DV_(CC)exhibit superior NRR catalytic performance,characterized by a low limiting potential of−0.33 and−0.43 V,respectively,which can be further increased under acid conditions based on the constant potential method.Moreover,varying NRR catalytic activities can be attributed to the differences in the valence state of active sites.Remarkably,further microkinetic modeling analysis displayed that the turnover frequency of N_(2)–to–NH_(3)conversion on Mo/DV_(CC)is as large as 1.20×10^(−3)s^(−1)site^(−1) at 700 K and 100 bar,thus guaranteeing its ultra-fast reaction rate.Our results not only suggest promising advanced electrocatalysts for NRR but also offer an effective avenue to regulate the electrocatalytic performance via the co-catalytic metal–support interactions.展开更多
Single atom catalysts(SACs)have garnered significant attention in the field of catalysis over the past decade due to their exceptional atom utilization efficiency and distinct physical and chemical properties.For the ...Single atom catalysts(SACs)have garnered significant attention in the field of catalysis over the past decade due to their exceptional atom utilization efficiency and distinct physical and chemical properties.For the semiconductor-based electrical gas sensor,the core is the catalysis process of target gas molecules on the sensitive materials.In this context,the SACs offer great potential for highly sensitive and selective gas sensing,however,only some of the bubbles come to the surface.To facilitate practical applications,we present a comprehensive review of the preparation strategies for SACs,with a focus on overcoming the challenges of aggregation and low loading.Extensive research efforts have been devoted to investigating the gas sensing mechanism,exploring sensitive materials,optimizing device structures,and refining signal post-processing techniques.Finally,the challenges and future perspectives on the SACs based gas sensing are presented.展开更多
Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enh...Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enhanced electrocatalytic performance,simultaneously provide a radical analysis of the interrelationship between structure and activity.In this review,the recent advances of single-atomic site catalysts coupled with clusters or nanoparticles are emphasized.Firstly,the synthetic strategies,characterization,dynamics and types of single atoms coupled with clusters/nanoparticles are introduced,and then the key factors controlling the structure of the composite catalysts are discussed.Next,several clean energy catalytic reactions performed over the synergistic composite catalysts are illustrated.Eventually,the encountering challenges and recommendations for the future advancement of synergistic structure in energy-transformation electrocatalysis are outlined.展开更多
High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current puri...High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current purification process is mainly based on the zone/electrolytic refining or anion exchange, however, which excessively relies on specific integrated equipment with ultra-high vacuum or chemical solution environment, and is also bothered by external contaminants and energy consumption. Here we report a simple approach to purify the Cu foils from 99.9%(3N) to 99.99%(4N) by a temperature-gradient thermal annealing technique, accompanied by the kinetic evolution of single crystallization of Cu.The success of purification mainly relies on(i) the segregation of elements with low effective distribution coefficient driven by grain-boundary movements and(ii) the high-temperature evaporation of elements with high saturated vapor pressure.The purified Cu foils display higher flexibility(elongation of 70%) and electrical conductivity(104% IACS) than that of the original commercial rolled Cu foils(elongation of 10%, electrical conductivity of ~ 100% IACS). Our results provide an effective strategy to optimize the as-produced metal medium, and therefore will facilitate the potential applications of Cu foils in precision electronic products and high-frequency printed circuit boards.展开更多
The photostability of a colloidal single photon emitter in near-infrared regime at room temperature is investigated.The fluorescence lifetime,blinking phenomenon,and anti-bunching effect of a single CdTeSe/ZnS quantum...The photostability of a colloidal single photon emitter in near-infrared regime at room temperature is investigated.The fluorescence lifetime,blinking phenomenon,and anti-bunching effect of a single CdTeSe/ZnS quantum dot with an emission wavelength of 800 nm at room temperature are studied.The second-order correlation function at zero delay time is much smaller than 0.1,which proves that the emission from single quantum dots at 800 nm is a highly pure single-photon source.The effects of the irradiation duration on the fluorescence from single quantum dots are analyzed.The experimental results can be explained by a recombination model including a multi-nonradiative recombination center model and a multi-charged model.展开更多
In paper[Chin.Phys.B 32070308(2023)],Xing et al.proposed a semi-quantum secret sharing protocol by using single particles.We study the security of the proposed protocol and find that it is not secure,that is,the three...In paper[Chin.Phys.B 32070308(2023)],Xing et al.proposed a semi-quantum secret sharing protocol by using single particles.We study the security of the proposed protocol and find that it is not secure,that is,the three dishonest agents,Bob,Charlie and Emily can collude to obtain Alice's secret without the help of David.展开更多
We report the growth of high-quality single crystals of RhP_(2),and systematically study its structure and physical properties by transport,magnetism,and heat capacity measurements.Single-crystal x-ray diffraction rev...We report the growth of high-quality single crystals of RhP_(2),and systematically study its structure and physical properties by transport,magnetism,and heat capacity measurements.Single-crystal x-ray diffraction reveals that RhP_(2) adopts a monoclinic structure with the cell parameters a=5.7347(10)A,b=5.7804(11)A,and c=5.8222(11)A,space group P2_(1)/c(No.14).The electrical resistivityρ(T)measurements indicate that RhP_(2) exhibits narrow-bandgap behavior with the activation energies of 223.1 meV and 27.4 meV for two distinct regions,respectively.The temperaturedependent Hall effect measurements show electron domain transport behavior with a low charge carrier concentration.We find that RhP_(2) has a high mobilityμ_(e)~210 cm^(2)·V^(-1)·s^(-1)with carrier concentrations n_(e)~3.3×10^(18)cm^(3) at 300 K with a narrow-bandgap feature.The high mobilityμ_(e) reaches the maximum of approximately 340 cm^(2)·V^(-1)·s^(-1)with carrier concentrations n_^(e)~2×10^(18)cm^(-3)at 100 K.No magnetic phase transitions are observed from the susceptibilityχ(T)and specific heat C_(p)(T)measurements of RhP_(2).Our results not only provide effective potential as a material platform for studying exotic physical properties and electron band structures but also motivate further exploration of their potential photovoltaic and optoelectronic applications.展开更多
Ultrasonic-assisted micro-electro-discharge machining(EDM)has the potential to enhance processing responses such as material removal rate(MRR)and surface finish.To understand the reasons for this enhancement,the physi...Ultrasonic-assisted micro-electro-discharge machining(EDM)has the potential to enhance processing responses such as material removal rate(MRR)and surface finish.To understand the reasons for this enhancement,the physical mechanisms responsible for the individual discharges and the craters that they form need to be explored.This work examines features of craters formed by single discharges at various parameter values in both conventional and ultrasonic-assistedEDM of Ti6Al4V.High-speed imaging of the plasma channel is performed,and data on the individual discharges are captured in real-time.A 2D axisymmetric model using finite element software is established to model crater formation.On the basis of simulation and experimental results,a comparative study is then carried out to examine the effects of ultrasonic vibrational assistance on crater geometry.For every set ofEDM parameters,the crater diameter and depth from a single discharge are found to be higher in ultrasonic-assistedEDM than in conventionalEDM.The improved crater geometry and the reduced bulge formation at the crater edges are attributed to the increased melt pool velocity and temperature predicted by the model.展开更多
Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and selectivity.However,most of the reported SA catalysts are...Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and selectivity.However,most of the reported SA catalysts are fixed through the strong bonding between the dispersed single metallic atoms with nonmetallic atoms of the substrates,which greatly limits the controllable regulation of electrocatalytic activity of SA catalysts.In this work,Pt-Ni bonded Pt SA catalyst with adjustable electronic states was successfully constructed through a controllable electrochemical reduction on the coordination unsaturated amorphous Ni(OH)_(2)nanosheet arrays.Based on the X-ray absorption fine structure analysis and first-principles calculations,Pt SA was bonded with Ni sites of amorphous Ni(OH)_(2),rather than conventional O sites,resulting in negatively charged Pt^(δ-).In situ Raman spectroscopy revealed that the changed configuration and electronic states greatly enhanced absorbability for activated hydrogen atoms,which were the essential intermediate for alkaline hydrogen evolution reaction.The hydrogen spillover process was revealed from amorphous Ni(OH)_(2)that effectively cleave the H-O-H bond of H_(2)O and produce H atom to the Pt SA sites,leading to a low overpotential of 48 mV in alkaline electrolyte at-1000 mA cm^(-2)mg^(-1)_(Pt),evidently better than commercial Pt/C catalysts.This work provided new strategy for the control-lable modulation of the local structure of SA catalysts and the systematic regulation of the electronic states.展开更多
We demonstrated a scheme of phase-locked terahertz quantum cascade lasers(THz QCLs)array,with a single-mode pulse power of 108 mW at 13 K.The device utilizes a Talbot cavity to achieve phase locking among five ridge l...We demonstrated a scheme of phase-locked terahertz quantum cascade lasers(THz QCLs)array,with a single-mode pulse power of 108 mW at 13 K.The device utilizes a Talbot cavity to achieve phase locking among five ridge lasers with first-order buried distributed feedback(DFB)grating,resulting in nearly five times amplification of the single-mode power.Due to the optimum length of Talbot cavity depends on wavelength,the combination of Talbot cavity with the DFB grating leads to better power amplification than the combination with multimode Fabry-Perot(F-P)cavities.The Talbot cavity facet reflects light back to the ridge array direction and achieves self-imaging in the array,enabling phase-locked operation of ridges.We set the spacing between adjacent elements to be 220μm,much larger than the free-space wavelength,ensuring the operation of the fundamental supermode throughout the laser's dynamic range and obtaining a high-brightness far-field distribution.This scheme provides a new approach for enhancing the single-mode power of THz QCLs.展开更多
Nickel(Ni)-rich cathode materials have become promising candidates for the next-generation electrical vehicles due to their high specific capacity.However,the poor thermodynamic stability(including cyclic performance ...Nickel(Ni)-rich cathode materials have become promising candidates for the next-generation electrical vehicles due to their high specific capacity.However,the poor thermodynamic stability(including cyclic performance and safety performance or thermal stability)will restrain their wide commercial application.Herein,a single-crystal Ni-rich Li Ni_(0.83)Co_(0.12)Mn_(0.05)O_(2) cathode material is synthesized and modified by a dual-substitution strategy in which the high-valence doping element improves the structural stability by forming strong metal–oxygen binding forces,while the low-valence doping element eliminates high Li^(+)/Ni^(2+)mixing.As a result,this synergistic dual substitution can effectively suppress H2-H3 phase transition and generation of microcracks,thereby ultimately improving the thermodynamic stability of Ni-rich cathode material.Notably,the dual-doped Ni-rich cathode delivers an extremely high capacity retention of 81%after 250 cycles(vs.Li/Li+)in coin-type half cells and 87%after 1000 cycles(vs.graphite/Li^(+))in pouch-type full cells at a high temperature of 55℃.More impressively,the dual-doped sample exhibits excellent thermal stability,which demonstrates a higher thermal runaway temperature and a lower calorific value.The synergetic effects of this dual-substitution strategy pave a new pathway for addressing the critical challenges of Ni-rich cathode at high temperatures,which will significantly advance the high-energy-density and high-safety cathodes to the subsequent commercialization.展开更多
Kagome magnets were predicted to be a good platform to investigate correlated topology band structure,Chern quantum phase,and geometrical frustration due to their unique lattice geometry.Here we reported single crysta...Kagome magnets were predicted to be a good platform to investigate correlated topology band structure,Chern quantum phase,and geometrical frustration due to their unique lattice geometry.Here we reported single crystal growth of 166-type kagome magnetic materials,including HfMn_(6)Sn_(6),ZrMn_(6)Sn_(6),GdMn_(6)Sn_(6)and GdV_(6)Sn_(6),by using the flux method with Sn as the flux.Among them,HfMn_(6)Sn_(6)and ZrMn_(6)Sn_(6)single crystals were grown for the first time.X-ray diffraction measurements reveal that all four samples crystallize in HfFe6Ge6-type hexagonal structure with space group P6/mmm.All samples show metallic behavior from temperature dependence of resistivity measurements,and the dominant carrier is hole,except for GdV6Sn6 which is electron dominated.All samples have magnetic order with different transition temperatures,HfMn_(6)Sn_(6),ZrMn_(6)Sn_(6)and GdV_(6)Sn_(6)are antiferromagnetic with TN of 541 K,466 K and 4 K respectively,while GdMn_(6)Sn_(6)is ferrimagnetic with the critical temperature of about 470 K.This study will enrich the research platform of magnetic kagome materials and help explore the novel quantum phenomena in these interesting materials.The dataset of specific crystal structure parameters for HfMn_(6)Sn_(6)are available in Science Data Bank,with the link.展开更多
Single Image Super-Resolution(SISR)technology aims to reconstruct a clear,high-resolution image with more information from an input low-resolution image that is blurry and contains less information.This technology has...Single Image Super-Resolution(SISR)technology aims to reconstruct a clear,high-resolution image with more information from an input low-resolution image that is blurry and contains less information.This technology has significant research value and is widely used in fields such as medical imaging,satellite image processing,and security surveillance.Despite significant progress in existing research,challenges remain in reconstructing clear and complex texture details,with issues such as edge blurring and artifacts still present.The visual perception effect still needs further enhancement.Therefore,this study proposes a Pyramid Separable Channel Attention Network(PSCAN)for the SISR task.Thismethod designs a convolutional backbone network composed of Pyramid Separable Channel Attention blocks to effectively extract and fuse multi-scale features.This expands the model’s receptive field,reduces resolution loss,and enhances the model’s ability to reconstruct texture details.Additionally,an innovative artifact loss function is designed to better distinguish between artifacts and real edge details,reducing artifacts in the reconstructed images.We conducted comprehensive ablation and comparative experiments on the Arabidopsis root image dataset and several public datasets.The experimental results show that the proposed PSCAN method achieves the best-known performance in both subjective visual effects and objective evaluation metrics,with improvements of 0.84 in Peak Signal-to-Noise Ratio(PSNR)and 0.017 in Structural Similarity Index(SSIM).This demonstrates that the method can effectively preserve high-frequency texture details,reduce artifacts,and have good generalization performance.展开更多
The oxidation behavior of a novel Ni-based single-crystal 4774DD1 superalloy for industrial gas turbine applications was investigated by the isothermal oxidation at 980℃ and discontinuous oxidation weight gain method...The oxidation behavior of a novel Ni-based single-crystal 4774DD1 superalloy for industrial gas turbine applications was investigated by the isothermal oxidation at 980℃ and discontinuous oxidation weight gain methods.The phase constitution and morphology of surface oxides and the characteristics of the crosssection oxide film were analyzed by XRD,SEM and EDS.Results show that the oxidation kinetics of the 4774DD1 superalloy follows the cubic law,indicating its weak oxidation resistance at this temperature.As the oxidation time increases,the composition of the oxide film evolves as following:One layer consisting of a bottom Al_(2)O_(3)sublayer and an upper(Al_(2)O_(3)+NiO)mixture sublayer after oxidized for 25 h.Then,two layers composed of an outermost small NiO discontinuous grain layer and an internal layer for 75 h.This internal layer is consisted of the bottom Al_(2)O_(3)sublayer,an intermediate narrow CrTaO_(4)sublayer,and an upper(Al_(2)O_(3)+NiO)mixture sublayer.Also two layers comprising an outermost relative continuous NiO layer with large grain size and an internal layer as the oxidation time increases to 125 h.This internal layer is composed of the upper(Al_(2)O_(3)+NiO)mixture sublayer,an intermediate continuous(CrTaO_(4)+NiWO_(4))mixture sublayer,and a bottom Al_(2)O_(3)sublayer.Finally,three layers consisting of an outermost(NiAl2O_(4)+NiCr2O_(4))mixture layer,an intermediate(CrTaO_(4)+NiWO_(4))mixture layer,and a bottom Al_(2)O_(3)layer for 200 h.展开更多
基金support from Horizon 2020 program within the ITN FlowcampDZ acknowledges funding from the Wohl Foundation for research for the promotion of UK-Israel research cooperationDZ acknowledges funding from Israel Ministry of Energy(grant#220-11-047).
文摘Utilizing supported single atoms as catalysts presents an opportunity to reduce the usage of critical raw materials such as platinum,which are essential for electrochemical reactions such as hydrogen oxidation reaction(HOR).Herein,we describe the synthesis of a Pt single electrocatalyst inside single-walled carbon nanotubes(SWCNTs)via a redox reaction.Characterizations via electron microscopy,X-ray photoelectron microscopy,and X-ray absorption spectroscopy show the single-atom nature of the Pt.The electrochemical behavior of the sample to hydrogen and oxygen was investigated using the advanced floating electrode technique,which minimizes mass transport limitations and gives a thorough insight into the activity of the electrocatalyst.The single-atom samples showed higher HOR activity than state-of-the-art 30%Pt/C while almost no oxygen reduction reaction activity in the proton exchange membrane fuel cell operating range.The selective activity toward HOR arose as the main fingerprint of the catalyst confinement in the SWCNTs.
基金support from the Shenzhen Science and Technology Program(No.KQTD20190929173914967,ZDSYS20220527171401003,and JCYJ20200109110416441).
文摘Single-atom catalysts(SACs)have gained substantial attention because of their exceptional catalytic properties.However,the high surface energy limits their synthesis,thus creating significant challenges for further development.In the last few years,metal–organic frameworks(MOFs)have received significant consideration as ideal candidates for synthesizing SACs due to their tailorable chemistry,tunable morphologies,high porosity,and chemical/thermal stability.From this perspective,this review thoroughly summarizes the previously reported methods and possible future approaches for constructing MOF-based(MOF-derived-supported and MOF-supported)SACs.Then,MOF-based SAC's identification techniques are briefly assessed to understand their coordination environments,local electronic structures,spatial distributions,and catalytic/electrochemical reaction mechanisms.This review systematically highlights several photocatalytic and electrocatalytic applications of MOF-based SACs for energy conversion and storage,including hydrogen evolution reactions,oxygen evolution reactions,O_(2)/CO_(2)/N_(2) reduction reactions,fuel cells,and rechargeable batteries.Some light is also shed on the future development of this highly exciting field by highlighting the advantages and limitations of MOF-based SACs.
基金supported by the National Natural Science Foundation of China(51872115,12234018 and 52101256)Beijing Synchrotron Radiation Facility(BSRF,4B9A)。
文摘Atom-level modulation of the coordination environment for single-atom catalysts(SACs)is considered as an effective strategy for elevating the catalytic performance.For the MNxsite,breaking the symmetrical geometry and charge distribution by introducing relatively weak electronegative atoms into the first/second shell is an efficient way,but it remains challenging for elucidating the underlying mechanism of interaction.Herein,a practical strategy was reported to rationally design single cobalt atoms coordinated with both phosphorus and nitrogen atoms in a hierarchically porous carbon derived from metal-organic frameworks.X-ray absorption spectrum reveals that atomically dispersed Co sites are coordinated with four N atoms in the first shell and varying numbers of P atoms in the second shell(denoted as Co-N/P-C).The prepared catalyst exhibits excellent oxygen reduction reaction(ORR)activity as well as zinc-air battery performance.The introduction of P atoms in the Co-SACs weakens the interaction between Co and N,significantly promoting the adsorption process of ^(*)OOH,resulting in the acceleration of reaction kinetics and reduction of thermodynamic barrier,responsible for the increased intrinsic activity.Our discovery provides insights into an ultimate design of single-atom catalysts with adjustable electrocatalytic activities for efficient electrochemical energy conversion.
文摘Single ventricle is an uncommon congenital cardiac pathology with high mortality at early ages. However, due to new strategies and timely surgical treatment, it is increasingly seen in adults, which has increased the survival rate. This condition is characterized by a heart with a single functional ventricular cavity. The aim of this article is to report the case of a 40-year-old male with single ventricle, who underwent several surgeries in his childhood. After these surgical procedures, the patient lost medical follow-up and presented complications derived from the disease itself. Heart Failure is a common complication in people with single ventricle, and pharmacological heart failure therapies have been ineffective in mitigating the need of the heart transplantation. That’s why it is essential to develop and apply new pharmacological techniques for the management of these patients in childhood as well as in adulthood. This would allow not only to avoid various comorbidities, but also to improve the quality of life of the patients.
文摘Background: World Health Organization recommends the implementation of contact tracing and Leprosy Post Exposure prophylaxis (LPEP) to interrupt the chain of transmission. To accelerate the uptake of this recommendation, a cross-sectional study among contacts of leprosy patients was conducted to investigate the feasibility of integrating leprosy systematic contact tracing and post-exposure prophylaxis (PEP) into the routine leprosy control program. Methods: This was a mixed methods cross-sectional study. The study was implemented in Kumi, Ngora, Serere, Soroti, Budaka and Kibuku Districts. Results: The 45 enrolled index patients (97.8% of the registered) identified a total of 135 contacts, of which 134 (99·2%) consented and were screened. Among them, one new leprosy patient was identified and started on treatment with multidrug therapy (MDT). All the eligible contacts, received the prophylactic treatment with Single Dose Rifampicin (SDR). Overall, SDR was administered to 133(98.5% of the listed contacts) with no adverse event reported. Factors associated with successful contact investigation and management included: Involvement of index patients, health care workers during the contact screening and SDR A administration, counselling of the index patients and contacts by the health care works, LPEP being administered as Directly observed Therapy (DOT) among others. Results Interpretation: The integration of leprosy post-exposure prophylaxis with administration of SDR and contact tracing is feasible, generally accepted by the patient, their contacts and health workers and can be integrated into the National Leprosy control programmes with minimal additional efforts once contact tracing has been established. Therefore, we recommend integration of administration of SDR in to the routine leprosy control program.
基金financially supported by the National Natural Science Foundation of China (22172044 and 22208048)Heilongjiang Provincial Natural Science Foundation of China (YQ2022B005 and YQ2022B001)+4 种基金the Young Elite Scientists Sponsorship Program by CAST (No.YESS20210262)the China Postdoctoral Science Foundation-Funded Project (No.2021M690571)the Heilongjiang Postdoctoral Fund (No.LBH-Z21096)the Provincial Natural Science Foundation Joint Guidance Project (No.LH2020F001)the Fundamental Research Funds for the Central Universities (No.2572023CT10)。
文摘Single-atom catalysts(SACs)are gaining popularity in catalytic reactions due to their nearly 100%atomic utilization and defined active sites,which provide great convenience for studying the catalytic mechanism of catalysts.However,SACs still present challenges such as complex formation processes,low loading and easy agglomeration of catalysts.Herein,we systematically discuss the synthesis methods for SACs,including coprecipitation,impregnation,atomic layer deposition,pyrolysis and Anti-Ostwald ripening etc.Various techniques for characterizing single-atom catalysts(SACs)are described in detail.The utilization of individual atoms in various photocatalytic reactions and their mechanisms of action in different reactions are explained.The purpose of this review is to introduce single-atom synthesis methods,characterization techniques,specific catalytic action and their applications in the direction of photocatalysis,and to provide a reference for the industrialization of photocatalytic single-atoms,which is currently impossible,in the hope of promoting further development of photocatalytic single-atoms.
基金financially supported in China by the Natural Science Funds for Distinguished Young Scholar of Heilongjiang Province (No. JC2018004)
文摘The co-catalysis between single atom catalyst(SAC)and its support has recently emerged as a promising strategy to synergistically boost the catalytic activity of some complex electrochemical reactions,encompassing multiple intermediates and pathways.Herein,we utilized defective BC_(3)monolayer-supported SACs as a prototype to investigate the cooperative effects of SACs and their support on the catalytic performance of the nitrogen reduction reaction(NRR)for ammonia(NH_(3))production.The results showed that these SACs can be firmly stabilized on these defective BC_(3)supports with high stability against aggregation.Furthermore,co-activation of the inert N_(2)reactant was observed in certain embedded SACs and their neighboring B atoms on certain BC3 sheets due to the noticeable charge transfer and significant N–N bond elongation.Our high-throughput screening revealed that the Mo/DV_(CC)and W/DV_(CC)exhibit superior NRR catalytic performance,characterized by a low limiting potential of−0.33 and−0.43 V,respectively,which can be further increased under acid conditions based on the constant potential method.Moreover,varying NRR catalytic activities can be attributed to the differences in the valence state of active sites.Remarkably,further microkinetic modeling analysis displayed that the turnover frequency of N_(2)–to–NH_(3)conversion on Mo/DV_(CC)is as large as 1.20×10^(−3)s^(−1)site^(−1) at 700 K and 100 bar,thus guaranteeing its ultra-fast reaction rate.Our results not only suggest promising advanced electrocatalysts for NRR but also offer an effective avenue to regulate the electrocatalytic performance via the co-catalytic metal–support interactions.
基金supported by the National Key Research and Development Program of China(2022YFB3204700)the National Natural Science Foundation of China(52122513)+2 种基金the Natural Science Foundation of Heilongjiang Province(YQ2021E022)the Natural Science Foundation of Chongqing(2023NSCQ-MSX2286)the Fundamental Research Funds for the Central Universities(HIT.BRET.2021010)。
文摘Single atom catalysts(SACs)have garnered significant attention in the field of catalysis over the past decade due to their exceptional atom utilization efficiency and distinct physical and chemical properties.For the semiconductor-based electrical gas sensor,the core is the catalysis process of target gas molecules on the sensitive materials.In this context,the SACs offer great potential for highly sensitive and selective gas sensing,however,only some of the bubbles come to the surface.To facilitate practical applications,we present a comprehensive review of the preparation strategies for SACs,with a focus on overcoming the challenges of aggregation and low loading.Extensive research efforts have been devoted to investigating the gas sensing mechanism,exploring sensitive materials,optimizing device structures,and refining signal post-processing techniques.Finally,the challenges and future perspectives on the SACs based gas sensing are presented.
基金financially supported by the National Natural Science Foundation of China(22279036)the Innovation Talent Recruitment Base of New Energy Chemistry Device(B21003)the Fundamental Research Funds for the Central Universities(no.2019kfyRCPY100).
文摘Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enhanced electrocatalytic performance,simultaneously provide a radical analysis of the interrelationship between structure and activity.In this review,the recent advances of single-atomic site catalysts coupled with clusters or nanoparticles are emphasized.Firstly,the synthetic strategies,characterization,dynamics and types of single atoms coupled with clusters/nanoparticles are introduced,and then the key factors controlling the structure of the composite catalysts are discussed.Next,several clean energy catalytic reactions performed over the synergistic composite catalysts are illustrated.Eventually,the encountering challenges and recommendations for the future advancement of synergistic structure in energy-transformation electrocatalysis are outlined.
基金Project supported by the Basic and Applied Basic Research Foundation of Guangdong Province,China(Grant Nos.2019A1515110302 and 2022A1515140003)the Key Research and Development Program of Guangdong Province,China(Grant Nos.2020B010189001,2021B0301030002,2019B010931001,and 2018B030327001)+5 种基金the National Natural Science Foundation of China(Grant Nos.52172035,52025023,52322205,51991342,52021006,51991344,52100115,11888101,92163206,12104018,and 12274456)the National Key Research and Development Program of China(Grant Nos.2021YFB3200303,2022YFA1405600,2018YFA0703700,2021YFA1400201,and 2021YFA1400502)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)the Pearl River Talent Recruitment Program of Guangdong Province,China(Grant No.2019ZT08C321)China Postdoctoral Science Foundation(Grant Nos.2020T130022 and 2020M680178)the Science and Technology Plan Project of Liaoning Province,China(Grant No.2021JH2/10100012).
文摘High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current purification process is mainly based on the zone/electrolytic refining or anion exchange, however, which excessively relies on specific integrated equipment with ultra-high vacuum or chemical solution environment, and is also bothered by external contaminants and energy consumption. Here we report a simple approach to purify the Cu foils from 99.9%(3N) to 99.99%(4N) by a temperature-gradient thermal annealing technique, accompanied by the kinetic evolution of single crystallization of Cu.The success of purification mainly relies on(i) the segregation of elements with low effective distribution coefficient driven by grain-boundary movements and(ii) the high-temperature evaporation of elements with high saturated vapor pressure.The purified Cu foils display higher flexibility(elongation of 70%) and electrical conductivity(104% IACS) than that of the original commercial rolled Cu foils(elongation of 10%, electrical conductivity of ~ 100% IACS). Our results provide an effective strategy to optimize the as-produced metal medium, and therefore will facilitate the potential applications of Cu foils in precision electronic products and high-frequency printed circuit boards.
基金Project supported by the National Natural Science Foundation of China(Grant No.92165202)the Innovation Program for Quantum Science and Technology,China(Grant No.2021ZD0300701)the Strategic Priority Research Program(A)of Chinese Academy of Sciences(Grant No.XDA18040300).
文摘The photostability of a colloidal single photon emitter in near-infrared regime at room temperature is investigated.The fluorescence lifetime,blinking phenomenon,and anti-bunching effect of a single CdTeSe/ZnS quantum dot with an emission wavelength of 800 nm at room temperature are studied.The second-order correlation function at zero delay time is much smaller than 0.1,which proves that the emission from single quantum dots at 800 nm is a highly pure single-photon source.The effects of the irradiation duration on the fluorescence from single quantum dots are analyzed.The experimental results can be explained by a recombination model including a multi-nonradiative recombination center model and a multi-charged model.
基金Project supported by the Offline Course Program of“Experiment of College Physics”in the 2022-year Anhui Provincial Quality Engineering Program (Grant No.2022xxkc134)the Program for Academic Leader Reserve Candidates in Tongling University (Grant Nos.2020tlxyxs43 and 2014tlxyxs30)+1 种基金the Talent Scientific Research Foundation of Tongling University (Grant No.2015tlxyrc01)the 2014 year Program for Excellent Youth Talents in University of Anhui Province。
文摘In paper[Chin.Phys.B 32070308(2023)],Xing et al.proposed a semi-quantum secret sharing protocol by using single particles.We study the security of the proposed protocol and find that it is not secure,that is,the three dishonest agents,Bob,Charlie and Emily can collude to obtain Alice's secret without the help of David.
基金supported by the National Key Research and Development Program of China (Grant No.2017YFA0302901)the Strategic Priority Research Program,the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences (Grant No.XDB33010100)+3 种基金the National Natural Science Foundation of China (Grant Nos.12134018,11921004,and 11634015)the Foundation of Quantum Science Center of Guangdong–Hong Kong–Macao Greater Bay Area,China (Grant No.QD2301005)the Postdoctoral Science Foundation of China (Grant No.2021M693370)the Synergetic Extreme Condition User Facility (SECUF)。
文摘We report the growth of high-quality single crystals of RhP_(2),and systematically study its structure and physical properties by transport,magnetism,and heat capacity measurements.Single-crystal x-ray diffraction reveals that RhP_(2) adopts a monoclinic structure with the cell parameters a=5.7347(10)A,b=5.7804(11)A,and c=5.8222(11)A,space group P2_(1)/c(No.14).The electrical resistivityρ(T)measurements indicate that RhP_(2) exhibits narrow-bandgap behavior with the activation energies of 223.1 meV and 27.4 meV for two distinct regions,respectively.The temperaturedependent Hall effect measurements show electron domain transport behavior with a low charge carrier concentration.We find that RhP_(2) has a high mobilityμ_(e)~210 cm^(2)·V^(-1)·s^(-1)with carrier concentrations n_(e)~3.3×10^(18)cm^(3) at 300 K with a narrow-bandgap feature.The high mobilityμ_(e) reaches the maximum of approximately 340 cm^(2)·V^(-1)·s^(-1)with carrier concentrations n_^(e)~2×10^(18)cm^(-3)at 100 K.No magnetic phase transitions are observed from the susceptibilityχ(T)and specific heat C_(p)(T)measurements of RhP_(2).Our results not only provide effective potential as a material platform for studying exotic physical properties and electron band structures but also motivate further exploration of their potential photovoltaic and optoelectronic applications.
基金support from the Department of Science and Technology (DST),Government of India (Grant No.ECR/DST/2017/000918)the Indian Institute of Technology Ropar for providing financial support under an ISIRD grant (F.No.9-282/2017IITRPR/705).
文摘Ultrasonic-assisted micro-electro-discharge machining(EDM)has the potential to enhance processing responses such as material removal rate(MRR)and surface finish.To understand the reasons for this enhancement,the physical mechanisms responsible for the individual discharges and the craters that they form need to be explored.This work examines features of craters formed by single discharges at various parameter values in both conventional and ultrasonic-assistedEDM of Ti6Al4V.High-speed imaging of the plasma channel is performed,and data on the individual discharges are captured in real-time.A 2D axisymmetric model using finite element software is established to model crater formation.On the basis of simulation and experimental results,a comparative study is then carried out to examine the effects of ultrasonic vibrational assistance on crater geometry.For every set ofEDM parameters,the crater diameter and depth from a single discharge are found to be higher in ultrasonic-assistedEDM than in conventionalEDM.The improved crater geometry and the reduced bulge formation at the crater edges are attributed to the increased melt pool velocity and temperature predicted by the model.
基金supported by National Natural Science Foundation of China(52373221,U1910208,52250119)the National Key R&D Program of China(2020YFA0710403)the Scientific Research Fund of Hunan Provincial Education Department(NO.23B0114).
文摘Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and selectivity.However,most of the reported SA catalysts are fixed through the strong bonding between the dispersed single metallic atoms with nonmetallic atoms of the substrates,which greatly limits the controllable regulation of electrocatalytic activity of SA catalysts.In this work,Pt-Ni bonded Pt SA catalyst with adjustable electronic states was successfully constructed through a controllable electrochemical reduction on the coordination unsaturated amorphous Ni(OH)_(2)nanosheet arrays.Based on the X-ray absorption fine structure analysis and first-principles calculations,Pt SA was bonded with Ni sites of amorphous Ni(OH)_(2),rather than conventional O sites,resulting in negatively charged Pt^(δ-).In situ Raman spectroscopy revealed that the changed configuration and electronic states greatly enhanced absorbability for activated hydrogen atoms,which were the essential intermediate for alkaline hydrogen evolution reaction.The hydrogen spillover process was revealed from amorphous Ni(OH)_(2)that effectively cleave the H-O-H bond of H_(2)O and produce H atom to the Pt SA sites,leading to a low overpotential of 48 mV in alkaline electrolyte at-1000 mA cm^(-2)mg^(-1)_(Pt),evidently better than commercial Pt/C catalysts.This work provided new strategy for the control-lable modulation of the local structure of SA catalysts and the systematic regulation of the electronic states.
基金funded by National Natural Science Foundation of China, grant numbers 62335006, 62274014, 62235016, 61734006, 61835011, 61991430funded by Key Program of the Chinese Academy of Sciences, grant numbers XDB43000000, QYZDJSSW-JSC027Beijing Municipal Science & Technology Commission, grant number Z221100002722018
文摘We demonstrated a scheme of phase-locked terahertz quantum cascade lasers(THz QCLs)array,with a single-mode pulse power of 108 mW at 13 K.The device utilizes a Talbot cavity to achieve phase locking among five ridge lasers with first-order buried distributed feedback(DFB)grating,resulting in nearly five times amplification of the single-mode power.Due to the optimum length of Talbot cavity depends on wavelength,the combination of Talbot cavity with the DFB grating leads to better power amplification than the combination with multimode Fabry-Perot(F-P)cavities.The Talbot cavity facet reflects light back to the ridge array direction and achieves self-imaging in the array,enabling phase-locked operation of ridges.We set the spacing between adjacent elements to be 220μm,much larger than the free-space wavelength,ensuring the operation of the fundamental supermode throughout the laser's dynamic range and obtaining a high-brightness far-field distribution.This scheme provides a new approach for enhancing the single-mode power of THz QCLs.
基金financially supported by the Natural Science Foundation of Jiangsu Province,China (BK20210887)the Jiangsu Provincial Double Innovation Program,China (JSSCB20210984)+1 种基金the Natural Science Fund for Colleges and Universities of Jiangsu Province,China (21KJB450003)the Jiangsu University of Science and Technology Doctoral Research Start-up Fund,China (120200012)。
文摘Nickel(Ni)-rich cathode materials have become promising candidates for the next-generation electrical vehicles due to their high specific capacity.However,the poor thermodynamic stability(including cyclic performance and safety performance or thermal stability)will restrain their wide commercial application.Herein,a single-crystal Ni-rich Li Ni_(0.83)Co_(0.12)Mn_(0.05)O_(2) cathode material is synthesized and modified by a dual-substitution strategy in which the high-valence doping element improves the structural stability by forming strong metal–oxygen binding forces,while the low-valence doping element eliminates high Li^(+)/Ni^(2+)mixing.As a result,this synergistic dual substitution can effectively suppress H2-H3 phase transition and generation of microcracks,thereby ultimately improving the thermodynamic stability of Ni-rich cathode material.Notably,the dual-doped Ni-rich cathode delivers an extremely high capacity retention of 81%after 250 cycles(vs.Li/Li+)in coin-type half cells and 87%after 1000 cycles(vs.graphite/Li^(+))in pouch-type full cells at a high temperature of 55℃.More impressively,the dual-doped sample exhibits excellent thermal stability,which demonstrates a higher thermal runaway temperature and a lower calorific value.The synergetic effects of this dual-substitution strategy pave a new pathway for addressing the critical challenges of Ni-rich cathode at high temperatures,which will significantly advance the high-energy-density and high-safety cathodes to the subsequent commercialization.
基金the Beijing Natural Science Founda-tion(Grant No.Z210006)the National Key Research and De-velopment Program of China(Grant Nos.2022YFA1403400 and 2020YFA0308800)the Beijing National Labora-tory for Condensed Matter Physics(Grant No.2023BNL-CMPKF007).
文摘Kagome magnets were predicted to be a good platform to investigate correlated topology band structure,Chern quantum phase,and geometrical frustration due to their unique lattice geometry.Here we reported single crystal growth of 166-type kagome magnetic materials,including HfMn_(6)Sn_(6),ZrMn_(6)Sn_(6),GdMn_(6)Sn_(6)and GdV_(6)Sn_(6),by using the flux method with Sn as the flux.Among them,HfMn_(6)Sn_(6)and ZrMn_(6)Sn_(6)single crystals were grown for the first time.X-ray diffraction measurements reveal that all four samples crystallize in HfFe6Ge6-type hexagonal structure with space group P6/mmm.All samples show metallic behavior from temperature dependence of resistivity measurements,and the dominant carrier is hole,except for GdV6Sn6 which is electron dominated.All samples have magnetic order with different transition temperatures,HfMn_(6)Sn_(6),ZrMn_(6)Sn_(6)and GdV_(6)Sn_(6)are antiferromagnetic with TN of 541 K,466 K and 4 K respectively,while GdMn_(6)Sn_(6)is ferrimagnetic with the critical temperature of about 470 K.This study will enrich the research platform of magnetic kagome materials and help explore the novel quantum phenomena in these interesting materials.The dataset of specific crystal structure parameters for HfMn_(6)Sn_(6)are available in Science Data Bank,with the link.
基金supported by Beijing Municipal Science and Technology Project(No.Z221100007122003).
文摘Single Image Super-Resolution(SISR)technology aims to reconstruct a clear,high-resolution image with more information from an input low-resolution image that is blurry and contains less information.This technology has significant research value and is widely used in fields such as medical imaging,satellite image processing,and security surveillance.Despite significant progress in existing research,challenges remain in reconstructing clear and complex texture details,with issues such as edge blurring and artifacts still present.The visual perception effect still needs further enhancement.Therefore,this study proposes a Pyramid Separable Channel Attention Network(PSCAN)for the SISR task.Thismethod designs a convolutional backbone network composed of Pyramid Separable Channel Attention blocks to effectively extract and fuse multi-scale features.This expands the model’s receptive field,reduces resolution loss,and enhances the model’s ability to reconstruct texture details.Additionally,an innovative artifact loss function is designed to better distinguish between artifacts and real edge details,reducing artifacts in the reconstructed images.We conducted comprehensive ablation and comparative experiments on the Arabidopsis root image dataset and several public datasets.The experimental results show that the proposed PSCAN method achieves the best-known performance in both subjective visual effects and objective evaluation metrics,with improvements of 0.84 in Peak Signal-to-Noise Ratio(PSNR)and 0.017 in Structural Similarity Index(SSIM).This demonstrates that the method can effectively preserve high-frequency texture details,reduce artifacts,and have good generalization performance.
基金supported by the fund of State Key Laboratory of Long-life High Temperature Materials(Grant No.DTCC28EE200787)the Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2022JQ-553)+3 种基金the China Postdoctoral Science Foundation(Grant No.2021M692555)the Excellent Youth Foundation of Shaanxi Province of China(Grant No.2021JC-08)the Beilin district of Xi’an Science and Technology Project(Grant No.GX2123)the support from the Youth Innovation Team of Shaanxi Universities。
文摘The oxidation behavior of a novel Ni-based single-crystal 4774DD1 superalloy for industrial gas turbine applications was investigated by the isothermal oxidation at 980℃ and discontinuous oxidation weight gain methods.The phase constitution and morphology of surface oxides and the characteristics of the crosssection oxide film were analyzed by XRD,SEM and EDS.Results show that the oxidation kinetics of the 4774DD1 superalloy follows the cubic law,indicating its weak oxidation resistance at this temperature.As the oxidation time increases,the composition of the oxide film evolves as following:One layer consisting of a bottom Al_(2)O_(3)sublayer and an upper(Al_(2)O_(3)+NiO)mixture sublayer after oxidized for 25 h.Then,two layers composed of an outermost small NiO discontinuous grain layer and an internal layer for 75 h.This internal layer is consisted of the bottom Al_(2)O_(3)sublayer,an intermediate narrow CrTaO_(4)sublayer,and an upper(Al_(2)O_(3)+NiO)mixture sublayer.Also two layers comprising an outermost relative continuous NiO layer with large grain size and an internal layer as the oxidation time increases to 125 h.This internal layer is composed of the upper(Al_(2)O_(3)+NiO)mixture sublayer,an intermediate continuous(CrTaO_(4)+NiWO_(4))mixture sublayer,and a bottom Al_(2)O_(3)sublayer.Finally,three layers consisting of an outermost(NiAl2O_(4)+NiCr2O_(4))mixture layer,an intermediate(CrTaO_(4)+NiWO_(4))mixture layer,and a bottom Al_(2)O_(3)layer for 200 h.
