The honeycomb magnet Na_(3)Co_(2)SbO_(6)recently emerged as a promising candidate for realizing Kitaev quantum spin liquid with relatively low levels of structural disorder.While the precise spin Hamiltonian remains c...The honeycomb magnet Na_(3)Co_(2)SbO_(6)recently emerged as a promising candidate for realizing Kitaev quantum spin liquid with relatively low levels of structural disorder.While the precise spin Hamiltonian remains controversial,the potential existence of a quantum spin liquid or other novel quantum magnetic phases continues to stimulate investigation.Here,we study the temperature and magnetic field-dependent spin excitations of Na_(3)Co_(2)SbO_(6)on a twin-free single crystal using magneto-terahertz(THz)spectroscopy,focusing on magnetic anisotropy and field-induced unusual phases.We observe a low-energy continuum excitation above T_(N)and a 0.5 THz(2 meV)spin wave excitation in magnetic order under zero field.Upon applying an in-plane magnetic field,the spin waves transform to a magnetic continuum over an intermediate field range,above which the system enters a spin-polarized state.Crucially,the spin excitation spectra reveal striking anisotropy between the a and b crystallographic axes,demanding description by a strongly anisotropic spin model.These findings establish Na_(3)Co_(2)SbO_(6)as a model system for investigating field-tunable quantum magnetism and potential spin liquid behavior in highly anisotropic systems.展开更多
To investigate the microstructure, segregation, and suitable homogenization process of as-cast GH4169D alloy, the microstructure, elements segregation, and precipitates of cast GH4169D ingots prepared by vacuum induct...To investigate the microstructure, segregation, and suitable homogenization process of as-cast GH4169D alloy, the microstructure, elements segregation, and precipitates of cast GH4169D ingots prepared by vacuum induction melting (VIM) and vacuum arc remelting (VAR) were observed by optical microscopy (OM), scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). According to the residual segregation model and simulation results of DICTRA thermodynamic software, the homogenization temperature and time range were set as 1120–1170°C and 5–20 h, respectively. The experimental results showed that microscopic dendrite and element segregation occurred in the interior of ingots and the main segregation elements were Nb and Ti. In addition, the precipitates were mainly distributed in interdendritic regions and were composed of NbC, Laves,γ′, and δ phases. The homogenization process suggested that the interdendritic detrimental precipitated Laves phase can be eliminated or redissolved after homogenization at 1150°C for 20 h, suggesting it was the most suitable homogenization treatment. Thermal compression test results showed that the GH4169D alloys after homogenization treatment had no cracks and dynamic recrystallization occurred, with recrystallization volume fraction increasing with temperature, indicating a good working plasticity at temperatures from 1050 to 1200°C.展开更多
The rise of the Internet and identity authentication systems has brought convenience to people's lives but has also introduced the potential risk of privacy leaks.Existing biometric authentication systems based on...The rise of the Internet and identity authentication systems has brought convenience to people's lives but has also introduced the potential risk of privacy leaks.Existing biometric authentication systems based on explicit and static features bear the risk of being attacked by mimicked data.This work proposes a highly efficient biometric authentication system based on transient eye blink signals that are precisely captured by a neuromorphic vision sensor with microsecond-level temporal resolution.The neuromorphic vision sensor only transmits the local pixel-level changes induced by the eye blinks when they occur,which leads to advantageous characteristics such as an ultra-low latency response.We first propose a set of effective biometric features describing the motion,speed,energy and frequency signal of eye blinks based on the microsecond temporal resolution of event densities.We then train the ensemble model and non-ensemble model with our Neuro Biometric dataset for biometrics authentication.The experiments show that our system is able to identify and verify the subjects with the ensemble model at an accuracy of 0.948 and with the non-ensemble model at an accuracy of 0.925.The low false positive rates(about 0.002)and the highly dynamic features are not only hard to reproduce but also avoid recording visible characteristics of a user's appearance.The proposed system sheds light on a new path towards safer authentication using neuromorphic vision sensors.展开更多
Objectives To assess the clinical efficacy,safety,and feasibility of autologous transplantation of mobilized peripheral blood mononuclear cells(PBMNCs)for patients with peripheral arterial occlusive disease(PAOD)of th...Objectives To assess the clinical efficacy,safety,and feasibility of autologous transplantation of mobilized peripheral blood mononuclear cells(PBMNCs)for patients with peripheral arterial occlusive disease(PAOD)of the lower extremity.Methods A total of 152 patients with PAOD of the lower extremity were enrolled into this non-controlled observational study from November 2003 to March 2006.All patients received subcutaneous injections of recombinant human granulocyte colony-stimulating factor(G-CSF,450-600μg/day)for 5 days in order to mobilize stem/progenitor cells;their PBMNCs were collected and transplanted by multiple intramuscular injections into ischemic limbs.Patients were followed up for at least 12 weeks.Results At 12 weeks,primary manifestations,including lower limb pain and coldness,were significantly improved in 137(90.1%)of the patients;limb ulcers improved or healed in 46(86.8%)of the 53 patients,while 25 of the 48(47.9%)patients with limb gangrene remained steady or improved.Ankle-brachial index(ABI)improved in 33(22%)of the cases,and TcPO_(2) increased in 45(30%)of the cases.Angiography before treatment,and at 12 weeks after treatment,was performed in 10 of the patients and showed formation of new collateral vessels.No severe adverse effects or complications specifically related to cell transplantation were observed.Conclusion Autologous transplantation of G-CSF-mobilized PBMNCs might be a safe and effective treatment for lower limb ischemic disorder.展开更多
Protection of frying oil from deterioration by adding plant phenolic extracts to guarantee the quality of fried foods becomes the primary approach to promote the sustainable development of deep frying.Therefore,source...Protection of frying oil from deterioration by adding plant phenolic extracts to guarantee the quality of fried foods becomes the primary approach to promote the sustainable development of deep frying.Therefore,sources,antioxidant effects,and mechanisms of plant phenolic extracts recently applied in the quality protection of frying oil as well as challenges for the actual use of these extracts are comprehensively reviewed in this study.Spices,herbs,berries,tea leaves,and fruit and vegetable wastes are common sources for preparing phenolic extracts showing comparative antioxidant capacity referring to the synthetic antioxidants.The general effect of using these natural antioxidants is the improvement of thermal stability to extend the shelf life of frying oil and thus the modification of edible quality of fried foods.Specifically,the increases in common quality attributes and amount of hazardous products and the oxidative reduction of unsaturated triacylglycerols without negatively influencing the sensory quality are inhibited when suitable plant extracts are applied.The incorporation of plant phenolic extracts other than synthetic counterparts in frying oil has been demonstrated as a potential method to improve the frying performance of oils.However,challenges for the scale application of plant phenolic extracts,such as the purity,thermal stability,and antioxidant timing,are still needed to be further investigated.展开更多
BK channels are widely expressed in both excitable and non-excitable cells and known to be involved in many physiological processes,such as vascular smooth tone regulation,neuronal firing and endocrine cell secretion[1].
Evaluating rainwater transport patterns is critical to understanding coupled hydrological cycles.However,water movement in heterogeneous landscapes exhibits pronounced complexity,particularly as the impacts of subsurf...Evaluating rainwater transport patterns is critical to understanding coupled hydrological cycles.However,water movement in heterogeneous landscapes exhibits pronounced complexity,particularly as the impacts of subsurface geotechnical structures remain inadequately understood.We applied water isotope tracers to compare mobile water recharge characteristics in two humid karst hillslopes with distinct soil thicknesses(deep-soil,DSH;shallow-soil,SSH).Mobile water was collected from(1)soil water at multiple depths across downslope-to-upslope positions,and(2)lateral subsurface runoff within the soil-bedrock system at discharge outlets.The rainwater replenishment proportion(β)and mean transit time(MTT)of soil water,and evaporated fractionation(f)in runoff during consecutive rainless days were used to quantify recharge characteristics.The results showed that the mean β value in SSH was 22.49%,exceeding the 15.07%in DSH.In contrast,the soil and runoff MTT in DSH(-42.41 days)was longer than in SSH(-30.58 days).These findings indicate that SSH mobile water exhibits a higher rainwater recharge ratio but a shorter residence time,which is associated with its stronger water infiltration capacity.As supporting evidence,SSH was more susceptible to evaporation,manifested by a higher f in SSH(13.5%)compared to DSH(9.3%).In DSH,a strong correlation(R^(2)=0.78)between β and MTT was observed,whereas this relationship was weak in SSH(R^(2)=0.16).Therefore,we highlight that the high heterogeneity of shallow soil hillslopes may render infiltration-runoff processes more complex and unpredictable in karst hillslopes in Southwest China.展开更多
Monolayer FeSe films grown on SrTiO_3(STO)substrate show superconducting gap-opening temperatures(T_c) which are almost an order of magnitude higher than those of the bulk FeSe and are highest among all known Fe-based...Monolayer FeSe films grown on SrTiO_3(STO)substrate show superconducting gap-opening temperatures(T_c) which are almost an order of magnitude higher than those of the bulk FeSe and are highest among all known Fe-based superconductors. Angle-resolved photoemission spectroscopy observed ‘‘replica bands' ' suggesting the importance of the interaction between FeSe electrons and STO phonons. These facts rejuvenated the quest for T_c enhancement mechanisms in iron-based, especially ironchalcogenide, superconductors. Here, we perform the first numerically-exact sign-problem-free quantum Monte Carlo simulations to iron-based superconductors. We(1) study the electronic pairing mechanism intrinsic to heavily electron doped FeSe films, and(2) examine the effects of electron–phonon interaction between FeSe and STO as well as nematic fluctuations on T_c. Armed with these results, we return to the question ‘‘what makes the Tcof monolayer FeSe on SrTiO_3 so high?'' in the conclusion and discussions.展开更多
In recent years,iridium oxides have attracted intensive research interests both in experiments and theories due to their comparable energy scales of the Coulomb repulsion and strong spin-orbit coupling(SOC)[1,2],where...In recent years,iridium oxides have attracted intensive research interests both in experiments and theories due to their comparable energy scales of the Coulomb repulsion and strong spin-orbit coupling(SOC)[1,2],where a plenty of novel quantum states such as Weyl semimetal,topological insulator and quantum spin liquid have been studied[3–7].Among the iridates,the layered-perovskite Sr2IrO4(SIO)is a Jeff=1/2 Mott insulating antiferromagnet caused by the interplay of the SOC and electronic correlations[8,9].展开更多
In this Perspective article we review retrospectively the streamline of our work on iron-based superconductors, and reflect on the mechanism of Cooper pairing in conventional and unconventional, such as iron-based sup...In this Perspective article we review retrospectively the streamline of our work on iron-based superconductors, and reflect on the mechanism of Cooper pairing in conventional and unconventional, such as iron-based superconductors. The main theme of this review is the concept of effective interaction and renormalization group.展开更多
A new quantum spin liquid(QSL)candidate material H3LiIr2O6 was synthesized recently and was found not to show any magnetic order or phase transition down to low temperatures.In this work,we study the quantum dynamics ...A new quantum spin liquid(QSL)candidate material H3LiIr2O6 was synthesized recently and was found not to show any magnetic order or phase transition down to low temperatures.In this work,we study the quantum dynamics of the hydrogen ions,i.e.,protons,in this material by combining first-principles calculations and theoretical analysis.We show that each proton and its adjacent oxygen ions form an electric dipole.The dipole interactions and the proton tunneling are captured by a transverse-field Ising model with a quantum disordered paraelectric ground state.The dipole excitations have an energy gap△d=60 meV,and can be probed by the infrared optical spectroscopy and the dielectric response.We argue that the electric dipole fluctuations renormalize the magnetic interactions in H3LiIr2O6 and lead to a Kitaev QSL state.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.12488201,12250008,12474138,and 12274004)the National Key Research and Development Program of China(Grant No.2021YFA1401901,2022YFA1403901,2023YFA1406002,and 2024YFA1408301)。
文摘The honeycomb magnet Na_(3)Co_(2)SbO_(6)recently emerged as a promising candidate for realizing Kitaev quantum spin liquid with relatively low levels of structural disorder.While the precise spin Hamiltonian remains controversial,the potential existence of a quantum spin liquid or other novel quantum magnetic phases continues to stimulate investigation.Here,we study the temperature and magnetic field-dependent spin excitations of Na_(3)Co_(2)SbO_(6)on a twin-free single crystal using magneto-terahertz(THz)spectroscopy,focusing on magnetic anisotropy and field-induced unusual phases.We observe a low-energy continuum excitation above T_(N)and a 0.5 THz(2 meV)spin wave excitation in magnetic order under zero field.Upon applying an in-plane magnetic field,the spin waves transform to a magnetic continuum over an intermediate field range,above which the system enters a spin-polarized state.Crucially,the spin excitation spectra reveal striking anisotropy between the a and b crystallographic axes,demanding description by a strongly anisotropic spin model.These findings establish Na_(3)Co_(2)SbO_(6)as a model system for investigating field-tunable quantum magnetism and potential spin liquid behavior in highly anisotropic systems.
基金the support of this research from the National Natural Science Foundation of China (Nos. 51571012 and 51771017)
文摘To investigate the microstructure, segregation, and suitable homogenization process of as-cast GH4169D alloy, the microstructure, elements segregation, and precipitates of cast GH4169D ingots prepared by vacuum induction melting (VIM) and vacuum arc remelting (VAR) were observed by optical microscopy (OM), scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). According to the residual segregation model and simulation results of DICTRA thermodynamic software, the homogenization temperature and time range were set as 1120–1170°C and 5–20 h, respectively. The experimental results showed that microscopic dendrite and element segregation occurred in the interior of ingots and the main segregation elements were Nb and Ti. In addition, the precipitates were mainly distributed in interdendritic regions and were composed of NbC, Laves,γ′, and δ phases. The homogenization process suggested that the interdendritic detrimental precipitated Laves phase can be eliminated or redissolved after homogenization at 1150°C for 20 h, suggesting it was the most suitable homogenization treatment. Thermal compression test results showed that the GH4169D alloys after homogenization treatment had no cracks and dynamic recrystallization occurred, with recrystallization volume fraction increasing with temperature, indicating a good working plasticity at temperatures from 1050 to 1200°C.
基金supported by the National Natural Science Foundation of China(61906138)the National Science and Technology Major Project of the Ministry of Science and Technology of China(2018AAA0102900)+2 种基金the Shanghai Automotive Industry Sci-Tech Development Program(1838)the European Union’s Horizon 2020 Research and Innovation Program(785907)the Shanghai AI Innovation Development Program 2018。
文摘The rise of the Internet and identity authentication systems has brought convenience to people's lives but has also introduced the potential risk of privacy leaks.Existing biometric authentication systems based on explicit and static features bear the risk of being attacked by mimicked data.This work proposes a highly efficient biometric authentication system based on transient eye blink signals that are precisely captured by a neuromorphic vision sensor with microsecond-level temporal resolution.The neuromorphic vision sensor only transmits the local pixel-level changes induced by the eye blinks when they occur,which leads to advantageous characteristics such as an ultra-low latency response.We first propose a set of effective biometric features describing the motion,speed,energy and frequency signal of eye blinks based on the microsecond temporal resolution of event densities.We then train the ensemble model and non-ensemble model with our Neuro Biometric dataset for biometrics authentication.The experiments show that our system is able to identify and verify the subjects with the ensemble model at an accuracy of 0.948 and with the non-ensemble model at an accuracy of 0.925.The low false positive rates(about 0.002)and the highly dynamic features are not only hard to reproduce but also avoid recording visible characteristics of a user's appearance.The proposed system sheds light on a new path towards safer authentication using neuromorphic vision sensors.
文摘Objectives To assess the clinical efficacy,safety,and feasibility of autologous transplantation of mobilized peripheral blood mononuclear cells(PBMNCs)for patients with peripheral arterial occlusive disease(PAOD)of the lower extremity.Methods A total of 152 patients with PAOD of the lower extremity were enrolled into this non-controlled observational study from November 2003 to March 2006.All patients received subcutaneous injections of recombinant human granulocyte colony-stimulating factor(G-CSF,450-600μg/day)for 5 days in order to mobilize stem/progenitor cells;their PBMNCs were collected and transplanted by multiple intramuscular injections into ischemic limbs.Patients were followed up for at least 12 weeks.Results At 12 weeks,primary manifestations,including lower limb pain and coldness,were significantly improved in 137(90.1%)of the patients;limb ulcers improved or healed in 46(86.8%)of the 53 patients,while 25 of the 48(47.9%)patients with limb gangrene remained steady or improved.Ankle-brachial index(ABI)improved in 33(22%)of the cases,and TcPO_(2) increased in 45(30%)of the cases.Angiography before treatment,and at 12 weeks after treatment,was performed in 10 of the patients and showed formation of new collateral vessels.No severe adverse effects or complications specifically related to cell transplantation were observed.Conclusion Autologous transplantation of G-CSF-mobilized PBMNCs might be a safe and effective treatment for lower limb ischemic disorder.
基金the National Natural Science Foundation of China(Grant No.32101981)。
文摘Protection of frying oil from deterioration by adding plant phenolic extracts to guarantee the quality of fried foods becomes the primary approach to promote the sustainable development of deep frying.Therefore,sources,antioxidant effects,and mechanisms of plant phenolic extracts recently applied in the quality protection of frying oil as well as challenges for the actual use of these extracts are comprehensively reviewed in this study.Spices,herbs,berries,tea leaves,and fruit and vegetable wastes are common sources for preparing phenolic extracts showing comparative antioxidant capacity referring to the synthetic antioxidants.The general effect of using these natural antioxidants is the improvement of thermal stability to extend the shelf life of frying oil and thus the modification of edible quality of fried foods.Specifically,the increases in common quality attributes and amount of hazardous products and the oxidative reduction of unsaturated triacylglycerols without negatively influencing the sensory quality are inhibited when suitable plant extracts are applied.The incorporation of plant phenolic extracts other than synthetic counterparts in frying oil has been demonstrated as a potential method to improve the frying performance of oils.However,challenges for the scale application of plant phenolic extracts,such as the purity,thermal stability,and antioxidant timing,are still needed to be further investigated.
基金supported by Natural Science Foundation of China grants10732070,10602031
文摘BK channels are widely expressed in both excitable and non-excitable cells and known to be involved in many physiological processes,such as vascular smooth tone regulation,neuronal firing and endocrine cell secretion[1].
基金supported by the National Natural Science Foundation of China(Grant Nos.U2344201,42407485)the Guangxi Natural Science Foundation(Grant No.2025GXNSFBA069189)the China Postdoctoral Science Foundation(Grant No.GZC20232970)。
文摘Evaluating rainwater transport patterns is critical to understanding coupled hydrological cycles.However,water movement in heterogeneous landscapes exhibits pronounced complexity,particularly as the impacts of subsurface geotechnical structures remain inadequately understood.We applied water isotope tracers to compare mobile water recharge characteristics in two humid karst hillslopes with distinct soil thicknesses(deep-soil,DSH;shallow-soil,SSH).Mobile water was collected from(1)soil water at multiple depths across downslope-to-upslope positions,and(2)lateral subsurface runoff within the soil-bedrock system at discharge outlets.The rainwater replenishment proportion(β)and mean transit time(MTT)of soil water,and evaporated fractionation(f)in runoff during consecutive rainless days were used to quantify recharge characteristics.The results showed that the mean β value in SSH was 22.49%,exceeding the 15.07%in DSH.In contrast,the soil and runoff MTT in DSH(-42.41 days)was longer than in SSH(-30.58 days).These findings indicate that SSH mobile water exhibits a higher rainwater recharge ratio but a shorter residence time,which is associated with its stronger water infiltration capacity.As supporting evidence,SSH was more susceptible to evaporation,manifested by a higher f in SSH(13.5%)compared to DSH(9.3%).In DSH,a strong correlation(R^(2)=0.78)between β and MTT was observed,whereas this relationship was weak in SSH(R^(2)=0.16).Therefore,we highlight that the high heterogeneity of shallow soil hillslopes may render infiltration-runoff processes more complex and unpredictable in karst hillslopes in Southwest China.
基金the National Supercomputer Center in Guangzhou for computational supportZXL and HY were supported in part by the National Thousand Young-Talents Program and the National Natural Science Foundation of China (11474175)+1 种基金FW was supported by the National Natural Science Foundation of China (11374018)DHL was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, Grant DE-AC0205CH11231
文摘Monolayer FeSe films grown on SrTiO_3(STO)substrate show superconducting gap-opening temperatures(T_c) which are almost an order of magnitude higher than those of the bulk FeSe and are highest among all known Fe-based superconductors. Angle-resolved photoemission spectroscopy observed ‘‘replica bands' ' suggesting the importance of the interaction between FeSe electrons and STO phonons. These facts rejuvenated the quest for T_c enhancement mechanisms in iron-based, especially ironchalcogenide, superconductors. Here, we perform the first numerically-exact sign-problem-free quantum Monte Carlo simulations to iron-based superconductors. We(1) study the electronic pairing mechanism intrinsic to heavily electron doped FeSe films, and(2) examine the effects of electron–phonon interaction between FeSe and STO as well as nematic fluctuations on T_c. Armed with these results, we return to the question ‘‘what makes the Tcof monolayer FeSe on SrTiO_3 so high?'' in the conclusion and discussions.
基金the support from the National Key Research and Development Program of China(2016YFA0302300)CAS Interdisciplinary Innovation Team+2 种基金the support from the National Natural Science Foundation of China(11974052)Beijing Natural Science Foundation(Z190008)the beamline 1W1A of Beijing Synchrotron Radiation Facility。
文摘In recent years,iridium oxides have attracted intensive research interests both in experiments and theories due to their comparable energy scales of the Coulomb repulsion and strong spin-orbit coupling(SOC)[1,2],where a plenty of novel quantum states such as Weyl semimetal,topological insulator and quantum spin liquid have been studied[3–7].Among the iridates,the layered-perovskite Sr2IrO4(SIO)is a Jeff=1/2 Mott insulating antiferromagnet caused by the interplay of the SOC and electronic correlations[8,9].
文摘In this Perspective article we review retrospectively the streamline of our work on iron-based superconductors, and reflect on the mechanism of Cooper pairing in conventional and unconventional, such as iron-based superconductors. The main theme of this review is the concept of effective interaction and renormalization group.
基金supported by the National Key Basic Research Program of China(Grant No.2014CB920902)the National Key Research and Development Program of China(Grant Nos.2017YFA0302904,and 2018YFA0305800)+2 种基金the National Natural Science Foundation of China(Grant No.11804337)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000)the Beijing Municipal Science&Technology Commission(Grant No.Z181100004218001)。
文摘A new quantum spin liquid(QSL)candidate material H3LiIr2O6 was synthesized recently and was found not to show any magnetic order or phase transition down to low temperatures.In this work,we study the quantum dynamics of the hydrogen ions,i.e.,protons,in this material by combining first-principles calculations and theoretical analysis.We show that each proton and its adjacent oxygen ions form an electric dipole.The dipole interactions and the proton tunneling are captured by a transverse-field Ising model with a quantum disordered paraelectric ground state.The dipole excitations have an energy gap△d=60 meV,and can be probed by the infrared optical spectroscopy and the dielectric response.We argue that the electric dipole fluctuations renormalize the magnetic interactions in H3LiIr2O6 and lead to a Kitaev QSL state.
