Purpose: To develop and test a mission-oriented and multi-dimensional benchmarking method for a small scale university aiming for internationally first-class basic research.Design/methodology/approach: An individualiz...Purpose: To develop and test a mission-oriented and multi-dimensional benchmarking method for a small scale university aiming for internationally first-class basic research.Design/methodology/approach: An individualized evidence-based assessment scheme was employed to benchmark ShanghaiTech University against selected top research institutions,focusing on research impact and competitiveness at the institutional and disciplinary levels.Topic maps opposing ShanghaiTech and corresponding top institutions were produced for the main research disciplines of ShanghaiTech. This provides opportunities for further exploration of strengths and weakness. Findings: This study establishes a preliminary framework for assessing the mission of the university. It further provides assessment principles, assessment questions, and indicators.Analytical methods and data sources were tested and proved to be applicable and efficient.Research limitations: To better fit the selective research focuses of this university, its schema of research disciplines needs to be re-organized and benchmarking targets should include disciplinary top institutions and not necessarily those universities leading overall rankings.Current reliance on research articles and certain databases may neglect important research output types.Practical implications: This study provides a working framework and practical methods for mission-oriented, individual, and multi-dimensional benchmarking that ShanghaiTech decided to use for periodical assessments. It also offers a working reference for other institutions to adapt. Further needs are identified so that ShanghaiTech can tackle them for future benchmarking.Originality/value: This is an effort to develop a mission-oriented, individually designed,systematically structured, and multi-dimensional assessment methodology which differs from often used composite indices.展开更多
X-ray photon correlation spectroscopy(XPCS)has emerged as a powerful tool for probing the nanoscale dynamics of soft condensed matter and strongly correlated materials owing to its high spatial resolution and penetrat...X-ray photon correlation spectroscopy(XPCS)has emerged as a powerful tool for probing the nanoscale dynamics of soft condensed matter and strongly correlated materials owing to its high spatial resolution and penetration capabilities.This technique requires high brilliance and beam coherence,which are not directly available at modern synchrotron beamlines in China.To facilitate future XPCS experiments,we modified the optical setup of the newly commissioned BL10U1 USAXS beamline at the Shanghai Synchrotron Radiation Facility(SSRF).Subsequently,we performed XPCS measurements on silica suspensions in glycerol,which were opaque owing to their high concentrations.Images were collected using a high frame rate area detector.A comprehensive analysis was performed,yielding correlation functions and several key dynamic parameters.All the results were consistent with the theory of Brownian motion and demonstrated the feasibility of XPCS at SSRF.Finally,by carefully optimizing the setup and analyzing the algorithms,we achieved a time resolution of 2 ms,which enabled the characterization of millisecond dynamics in opaque systems.展开更多
General anesthesia is widely applied in clinical practice.However,the precise mechanism of loss of consciousness induced by general anesthetics remains unknown.Here,we measured the dynamics of five neurotransmitters,i...General anesthesia is widely applied in clinical practice.However,the precise mechanism of loss of consciousness induced by general anesthetics remains unknown.Here,we measured the dynamics of five neurotransmitters,includingγ-aminobutyric acid,glutamate,norepinephrine,acetylcholine,and dopamine,in the medial prefrontal cortex and primary visual cortex of C57BL/6 mice through in vivo fiber photometry and genetically encoded neurotransmitter sensors under anesthesia to reveal the mechanism of general anesthesia from a neurotransmitter perspective.Results revealed that the concentrations of γ-aminobutyric acid,glutamate,norepinephrine,and acetylcholine increased in the cortex during propofol-induced loss of consciousness.Dopamine levels did not change following the hypnotic dose of propofol but increased significantly following surgical doses of propofol anesthesia.Notably,the concentrations of the five neurotransmitters generally decreased during sevoflurane-induced loss of consciousness.Furthermore,the neurotransmitter dynamic networks were not synchronized in the non-anesthesia groups but were highly synchronized in the anesthetic groups.These findings suggest that neurotransmitter dynamic network synchronization may cause anesthetic-induced loss of consciousness.展开更多
The utilization of processing capabilities within the detector holds significant promise in addressing energy consumption and latency challenges. Especially in the context of dynamic motion recognition tasks, where su...The utilization of processing capabilities within the detector holds significant promise in addressing energy consumption and latency challenges. Especially in the context of dynamic motion recognition tasks, where substantial data transfers are necessitated by the generation of extensive information and the need for frame-by-frame analysis. Herein, we present a novel approach for dynamic motion recognition, leveraging a spatial-temporal in-sensor computing system rooted in multiframe integration by employing photodetector. Our approach introduced a retinomorphic MoS_(2) photodetector device for motion detection and analysis. The device enables the generation of informative final states, nonlinearly embedding both past and present frames. Subsequent multiply-accumulate (MAC) calculations are efficiently performed as the classifier. When evaluating our devices for target detection and direction classification, we achieved an impressive recognition accuracy of 93.5%. By eliminating the need for frame-by-frame analysis, our system not only achieves high precision but also facilitates energy-efficient in-sensor computing.展开更多
We theoretically study the charge order and orbital magnetic properties of a new type of antiferromagnetic kagome metal FeGe.Based on first-principles density functional theory calculations,we study the electronic str...We theoretically study the charge order and orbital magnetic properties of a new type of antiferromagnetic kagome metal FeGe.Based on first-principles density functional theory calculations,we study the electronic structures,Fermi-surface quantum fluctuations,as well as phonon properties of the antiferromagnetic kagome metal FeGe.It is found that charge density wave emerges in such a system due to a subtle cooperation between electron-electron interactions and electron–phonon couplings,which gives rise to an unusual scenario of interaction-triggered phonon instabilities,and eventually yields a charge density wave(CDW)state.We further show that,in the CDW phase,the ground-state current density distribution exhibits an intriguing star-of-David pattern,leading to flux density modulation.The orbital fluxes(or current loops)in this system emerge as a result of the subtle interplay between magnetism,lattice geometries,charge order,and spin-orbit coupling(SOC),which can be described by a simple,yet universal,tight-binding theory including a Kane-Mele-type SOC term and a magnetic exchange interaction.We further study the origin of the peculiar step-edge states in FeGe,which sheds light on the topological properties and correlation effects in this new type of kagome antiferromagnetic material.展开更多
With the implementation of the Belt and Road Initiative, China is deepening its cooperation in oil and gas resources with countries along the Initiative. In order to better mitigate risks and enhance the safety of inv...With the implementation of the Belt and Road Initiative, China is deepening its cooperation in oil and gas resources with countries along the Initiative. In order to better mitigate risks and enhance the safety of investments, it is of significant importance to research the oil and gas investment environment in these countries for China's overseas investment macro-layout. This paper proposes an indicator system including 27 indicators from 6 dimensions. On this basis, game theory models combined with global entropy method and analytic hierarchy process are applied to determine the combined weights, and the TOPSIS-GRA model is utilized to assess the risks of oil and gas investment in 76 countries along the Initiative from 2014 to 2021. Finally, the GM(1,1) model is employed to predict risk values for 2022-2025. In conclusion, oil and gas resources and political factors have the greatest impact on investment environment risk, and 12 countries with greater investment potential are selected through cluster analysis in conjunction with the predicted results. The research findings may provide scientific decisionmaking recommendations for the Chinese government and oil enterprises to strengthen oil and gas investment cooperation with countries along the Belt and Road Initiative.展开更多
Oxynitride semiconductors are promising photocatalyst materials for visible light-driven water splitting,while the synthesis of well crystalized oxynitride still remains challenge.In present work,narrow-bandgap TaON n...Oxynitride semiconductors are promising photocatalyst materials for visible light-driven water splitting,while the synthesis of well crystalized oxynitride still remains challenge.In present work,narrow-bandgap TaON nanoparticles are synthesized via heating a vacuum-sealed mixture of KTaO_(3),Ta and NH_(4)Cl.This method possesses multiple advantages in terms of lower calcination parameter,higher N conversion efficiency and superior photocatalytic activity in comparison with the traditional thermal ammonolysis using NH_(3) gas as a nitrogen source.Through the analysis of intermediates produced upon the elevation of heating temperature,a gas-solid-phase reaction between TaCl_(5) and Ta_(2)O_(5) is demonstrated as the final step,which is conducive to decreasing thermal energy barrier and accelerating nitridation process.Precise control of preparation conditions,including calcination temperature and duration,allows for the regulation of surface O/N ratio of TaON particles to unity,resulting in optimized photocat-alytic activity.Photoelectrochemical assessment and intensity modulated photocurrent spectroscopy provide convincing evidence for improved charge transfer effciency of photoexcited holes at TaON surface.A Z-scheme overall water splitting is accomplished by employing the TaON as an effective oxygen evolution photocatalyst,SrTiO_(3):Rh as a hydrogen evolution photocatalyst,and reduced graphene oxide(rGO)as a solid-state electron mediator.This work presents a promising strategy for the synthesis of high-quality oxynitride materials in application to photocatalytic water splitting.展开更多
The dynamics beamline(D-Line),which combines synchrotron radiation infrared spectroscopy(SR-IR)and energy-disper-sive X-ray absorption spectroscopy(ED-XAS),is the first beamline in the world to realize concurrent ED-X...The dynamics beamline(D-Line),which combines synchrotron radiation infrared spectroscopy(SR-IR)and energy-disper-sive X-ray absorption spectroscopy(ED-XAS),is the first beamline in the world to realize concurrent ED-XAS and SR-IR measurements at the same sample position on a millisecond time-resolved scale.This combined technique is effective for investigating rapid structural changes in atoms,electrons,and molecules in complicated disorder systems,such as those used in physics,chemistry,materials science,and extreme conditions.Moreover,ED-XAS and SR-IR can be used independently in the two branches of the D-Line.The ED-XAS branch is the first ED-XAS beamline in China,which uses a tapered undulator light source and can achieve approximately 2.5×10^(12)photons/s·300 eV BW@7.2 keV at the sample position.An exchange-able polychromator operating in the Bragg-reflection or Laue-transmission configuration is used in different energy ranges to satisfy the requirements for beam size and energy resolution.The focused beam size is approximately 3.5μm(H)×21.5μm(V),and the X-ray energy range is 5–25 keV.Using one-and two-dimensional position-sensitive detectors with frame rates of up to 400 kHz enables time resolutions of tens of microseconds to be realized.Several distinctive techniques,such as the concurrent measurement of in situ ED-XAS and infrared spectroscopy,time-resolved ED-XAS,high-pressure ED-XAS,XMCD,and pump-probe ED-XAS,can be applied to achieve different scientific goals.展开更多
Fewest-switches surfacing hopping(FSSH) simulations have been performed with the high-level multi-reference electronic structure method to explore the coupled electronic and nuclear dynamics upon photoexcitation of cy...Fewest-switches surfacing hopping(FSSH) simulations have been performed with the high-level multi-reference electronic structure method to explore the coupled electronic and nuclear dynamics upon photoexcitation of cyanogen bromide(BrCN). The potential energy surfaces(PES) of BrCN are charted as functions of the Jacobi coordinates(R, θ). An indepth examination of the FSSH trajectories reveals the temporal dynamics of the molecule and the population changes of the lowest twelve states during BrCN's photodissociation process, which presents a rich tapestry of dynamical information.Furthermore, the carbon K-edge x-ray absorption spectroscopy(XAS) is calculated with multi-reference inner-shell spectral simulations. The rotation of the CN fragment and the elongation of the C–Br bond are found to be the reason for the peak shifting in the XAS. Our findings offer a nuanced interpretation for inner-shell probe investigations of BrCN, setting the stage for a deeper understanding of the photodissociation process of cyanogen halides molecules.展开更多
Chromium tellurium compounds are important two-dimensional van der Waals ferromagnetic materials with high Curie temperature and chemical stability in air,which is promising for applications in spintronic devices.Here...Chromium tellurium compounds are important two-dimensional van der Waals ferromagnetic materials with high Curie temperature and chemical stability in air,which is promising for applications in spintronic devices.Here,highquality spin-orbital-torque(SOT)device,Bi_(2)Te_(3)/CrTe_(2)heterostructure was epitaxially grown on Al_(2)O_(3)(0001)substrates.Anomalous Hall measurements indicate the existence of strong ferromagnetism in this device with the CrTe_(2)thickness down to 10 nm.In order to investigate its micromagnetic structure,cryogenic magnetic force microscope(MFM)was utilized to measure the magnetic domain evolutions at various temperatures and magnetic fields.The virgin domain state of the device shows a worm-like magnetic domain structure with the size around 0.6μm-0.8μm.Larger irregular-shape magnetic domains(>1μm)can be induced and pinned,after the field is increased to coercive field and ramped back to low fields.The temperature-dependent MFM signals exhibit a nice mean-field-like ferromagnetic transition with Curie temperature around 201.5 K,indicating a robust ferromagnetic ordering.Such a device can be potentially implemented in future magnetic memory technology.展开更多
Parkinson’s disease is a progressive neurodegenerative disease characterized by motor deficits,dopaminergic neuron loss,and brain accumulation ofα-synuclein aggregates called Lewy bodies.Dysfunction in protein degra...Parkinson’s disease is a progressive neurodegenerative disease characterized by motor deficits,dopaminergic neuron loss,and brain accumulation ofα-synuclein aggregates called Lewy bodies.Dysfunction in protein degradation pathways,such as autophagy,has been demonstrated in neurons as a critical mechanism for eliminating protein aggregates in Parkinson’s disease.However,it is less well understood how protein aggregates are eliminated in glia,the other cell type in the brain.In the present study,we show that autophagy-related gene 9(Atg9),the only transmembrane protein in the autophagy machinery,is highly expressed in Drosophila glia from adult brain.Results from immunostaining and live cell imaging analysis reveal that a portion of Atg9 localizes to the trans-Golgi network,autophagosomes,and lysosomes in glia.Atg9 is persistently in contact with these organelles.Lacking glial atg9 reduces the number of omegasomes and autophagosomes,and impairs autophagic substrate degradation.This suggests that glial Atg9 participates in the early steps of autophagy,and hence the control of autophagic degradation.Importantly,loss of glial atg9 induces parkinsonian symptoms in Drosophila including progressive loss of dopaminergic neurons,locomotion deficits,and glial activation.Our findings identify a functional role of Atg9 in glial autophagy and establish a potential link between glial autophagy and Parkinson’s disease.These results may provide new insights on the underlying mechanism of Parkinson’s disease.展开更多
In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl me...In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification.The effect of the absorbed dose was investigated in the range of 5–50 kGy.NWF-serine was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,and scanning electron microscopy.Batch adsorption tests were conducted to investigate the influences of pH,adsorption time,temperature,initial concentration,and sorbent dosage on the Pb(Ⅱ) adsorption performance of NWF-serine.The results indicated that Pb(Ⅱ) adsorption onto NWF-serine was an endothermic process,following the pseudo-second-order kinetic model and Langmuir isotherm model.The saturated adsorption capacity was 198.1 mg/g.NWF-serine exhibited Pb(Ⅱ) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd,Cu,Ni,Mn,and Zn.Furthermore,NWF-serine maintained 86% of its Pb(Ⅱ) uptake after five use cycles.The coordination of the carboxyl and amino groups with Pb(Ⅱ) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.展开更多
We report a linear-scaling random Green's function(rGF) method for large-scale electronic structure calculation. In this method, the rGF is defined on a set of random states and is efficiently calculated by projec...We report a linear-scaling random Green's function(rGF) method for large-scale electronic structure calculation. In this method, the rGF is defined on a set of random states and is efficiently calculated by projecting onto Krylov subspace. With the rGF method, the Fermi–Dirac operator can be obtained directly, avoiding the polynomial expansion to Fermi–Dirac function. To demonstrate the applicability, we implement the rGF method with the density-functional tight-binding method. It is shown that the Krylov subspace can maintain at small size for materials with different gaps at zero temperature, including H_(2)O and Si clusters. We find with a simple deflation technique that the rGF self-consistent calculation of H_(2)O clusters at T = 0 K can reach an error of~ 1 me V per H_(2)O molecule in total energy, compared to deterministic calculations. The rGF method provides an effective stochastic method for large-scale electronic structure simulation.展开更多
Recently, giant intrinsic anomalous Hall effect(AHE) has been observed in the materials with kagome lattice.Here, we systematically investigate the influence of high pressure on the AHE in the ferromagnet LiMn_(6)Sn_(...Recently, giant intrinsic anomalous Hall effect(AHE) has been observed in the materials with kagome lattice.Here, we systematically investigate the influence of high pressure on the AHE in the ferromagnet LiMn_(6)Sn_(6) with clean Mn kagome lattice. Our in situ high-pressure Raman spectroscopy indicates that the crystal structure of LiMn_(6)Sn_(6) maintains a hexagonal phase under high pressures up to 8.51 GPa. The anomalous Hall conductivity(AHC) σ_(xy)^(A) remains around 150 Ω^(-1)·cm^(-1), dominated by the intrinsic mechanism. Combined with theoretical calculations, our results indicate that the stable AHE under pressure in Li Mn_(6)Sn_(6) originates from the robust electronic and magnetic structure.展开更多
With the integration of ultrafast reflectivity and polarimetry probes,we observed carrier relaxation and spin dynamics induced by ultrafast laser excitation of Ni(111)single crystals.The carrier relaxation time within...With the integration of ultrafast reflectivity and polarimetry probes,we observed carrier relaxation and spin dynamics induced by ultrafast laser excitation of Ni(111)single crystals.The carrier relaxation time within the linear excitation range reveals that electron-phonon coupling and dissipation of photon energy into the bulk of the crystal take tens of picoseconds.On the other hand,the observed spin dynamics indicate a longer time of about 120 ps.To further understand how the lattice degree of freedom is coupled with these dynamics may require the integration of an ultrafast diffraction probe.展开更多
The REAgSb_(2)(RE = rare earth and Y) family has drawn considerable research interest because the two-dimensional Sb net in their crystal structures hosts topological fermions and hence rich topological properties. We...The REAgSb_(2)(RE = rare earth and Y) family has drawn considerable research interest because the two-dimensional Sb net in their crystal structures hosts topological fermions and hence rich topological properties. We report herein the magnetization and magnetotransport measurements of SmAgSb_(2) single crystal, which unveil very large magnetoresistance and high carrier mobility up to 6.2 × 10^(3)% and 5.58 × 10^(3)cm^(2)·V^(-1)·s^(-1), respectively. The analysis of both Shubnikov–de Haas and de Haas–van Alphen quantum oscillations indicates nontrivial Berry phases in the paramagnetic state while trivial Berry curvature in the antiferromagnetic state, indicating a topological phase transition induced by the antiferromagnetic order. It is also supported by the first-principles calculations. The results not only provide a new interesting topological material but also offer valuable insights into the correlation between magnetism and nontrivial topological states.展开更多
Radio frequency quadrupoles(RFQs),which are crucial components of proton injectors,significantly affect the performance of proton accelerator facilities.An RFQ with a high frequency of 714 MHz dedicated to compact pro...Radio frequency quadrupoles(RFQs),which are crucial components of proton injectors,significantly affect the performance of proton accelerator facilities.An RFQ with a high frequency of 714 MHz dedicated to compact proton injectors for medi-cal applications is designed in this study.The RFQ is designed to accelerate proton beams from 50 keV to 4 MeV within a short length of 2 m and can be matched closely with the downstream drift tube linac to capture more particles through a preliminary optimization.To develop an advanced RFQ,challenging techniques,including fabrication and tuning method,must be evaluated and verified using a prototype.An aluminium prototype is derived from the conceptual design of the RFQ and then redesigned to confirm the radio frequency performance,fabrication procedure,and feasibility of the tuning algorithm.Eventually,a new tuning algorithm based on the response matrix and least-squares method is developed,which yields favorable results based on the prototype,i.e.,the errors of the dipole and quadrupole components reduced to a low level after several tuning iterations.Benefiting from the conceptual design and techniques obtained from the prototype,the formal mechanical design of the 2-m RFQ is ready for the next manufacturing step.展开更多
Magnetic topological semimetals have been at the forefront of condensed matter physics due to their ability to exhibit exotic transport phenomena.Investigating the interplay between magnetic and topological orders in ...Magnetic topological semimetals have been at the forefront of condensed matter physics due to their ability to exhibit exotic transport phenomena.Investigating the interplay between magnetic and topological orders in systems with broken time-reversal symmetry is crucial for realizing non-trivial quantum effects.We delve into the electronic structure of the rare-earth-based antiferromagnetic Dirac semimetal EuMg_(2)Bi_(2) using first-principles calculations and angle-resolved photoemission spectroscopy.Our calculations reveal that the spin-orbit coupling(SOC)in EuMg_(2)Bi_(2) prompts an insulator to topological semimetal transition,with the Dirac bands protected by crystal symmetries.The linearly dispersive states near the Fermi level,primarily originating from Bi 6p orbitals,are observed on both the(001)and(100)surfaces,confirming that EuMg_(2)Bi_(2) is a three-dimensional topological Dirac semimetal.This research offers pivotal insights into the interplay between magnetism,SOC and topological phase transitions in spintronics applications.展开更多
Emission and capture characteristics of a deep hole trap(H1)in n-GaN Schottky barrier diodes(SBDs)have been investigated by optical deep level transient spectroscopy(ODLTS).Activation energy(Eemi)and capture cross-sec...Emission and capture characteristics of a deep hole trap(H1)in n-GaN Schottky barrier diodes(SBDs)have been investigated by optical deep level transient spectroscopy(ODLTS).Activation energy(Eemi)and capture cross-section(σ_(p))of H1 are determined to be 0.75 eV and 4.67×10^(−15)cm^(2),respectively.Distribution of apparent trap concentration in space charge region is demonstrated.Temperature-enhanced emission process is revealed by decrease of emission time constant.Electricfield-boosted trap emission kinetics are analyzed by the Poole−Frenkel emission(PFE)model.In addition,H1 shows point defect capture properties and temperature-enhanced capture kinetics.Taking both hole capture and emission processes into account during laser beam incidence,H1 features a trap concentration of 2.67×10^(15)cm^(−3).The method and obtained results may facilitate understanding of minority carrier trap properties in wide bandgap semiconductor material and can be applied for device reliability assessment.展开更多
This study presents a new method for characterizing the thermal lattice deformation of a monochromator with high precision under service conditions and first reports the operando measurements of nanoscale thermal latt...This study presents a new method for characterizing the thermal lattice deformation of a monochromator with high precision under service conditions and first reports the operando measurements of nanoscale thermal lattice deformation on a double-crystal monochromator at different incident powers.The nanoscale thermal lattice deformation of the monochromator first crystal was obtained by analyzing the intensity of the distorted DuMond diagrams.DuMond diagrams of the 333 diffraction index,sensitive to lattice deformation,were obtained directly using a 2D detector and an analyzer crystal orthogonal to the monochromator.With increasing incident power and power density,the maximum height of the lattice deformation increased from 3.2 to 18.5 nm,and the deformation coefficient of the maximum height increased from 1.1 to 3.2 nm/W.The maximum relative standard deviation was 4.2%,and the maximum standard deviation was 0.1 nm.Based on the measured thermal deformations,the flux saturation phenomenon and critical point for the linear operation of the monochromator were predicted with increasing incident power.This study provides a simple solution to the problem of the lower precision of synchrotron radiation monochromator characterizations compared to simulations.展开更多
文摘Purpose: To develop and test a mission-oriented and multi-dimensional benchmarking method for a small scale university aiming for internationally first-class basic research.Design/methodology/approach: An individualized evidence-based assessment scheme was employed to benchmark ShanghaiTech University against selected top research institutions,focusing on research impact and competitiveness at the institutional and disciplinary levels.Topic maps opposing ShanghaiTech and corresponding top institutions were produced for the main research disciplines of ShanghaiTech. This provides opportunities for further exploration of strengths and weakness. Findings: This study establishes a preliminary framework for assessing the mission of the university. It further provides assessment principles, assessment questions, and indicators.Analytical methods and data sources were tested and proved to be applicable and efficient.Research limitations: To better fit the selective research focuses of this university, its schema of research disciplines needs to be re-organized and benchmarking targets should include disciplinary top institutions and not necessarily those universities leading overall rankings.Current reliance on research articles and certain databases may neglect important research output types.Practical implications: This study provides a working framework and practical methods for mission-oriented, individual, and multi-dimensional benchmarking that ShanghaiTech decided to use for periodical assessments. It also offers a working reference for other institutions to adapt. Further needs are identified so that ShanghaiTech can tackle them for future benchmarking.Originality/value: This is an effort to develop a mission-oriented, individually designed,systematically structured, and multi-dimensional assessment methodology which differs from often used composite indices.
基金This work was supported by National Natural Science Foundation of China(No.12075304)Natural Science Foundation of Shanghai(No.22ZR1442100)National Key Research and Development Program of China(No.2022YFB3503904).
文摘X-ray photon correlation spectroscopy(XPCS)has emerged as a powerful tool for probing the nanoscale dynamics of soft condensed matter and strongly correlated materials owing to its high spatial resolution and penetration capabilities.This technique requires high brilliance and beam coherence,which are not directly available at modern synchrotron beamlines in China.To facilitate future XPCS experiments,we modified the optical setup of the newly commissioned BL10U1 USAXS beamline at the Shanghai Synchrotron Radiation Facility(SSRF).Subsequently,we performed XPCS measurements on silica suspensions in glycerol,which were opaque owing to their high concentrations.Images were collected using a high frame rate area detector.A comprehensive analysis was performed,yielding correlation functions and several key dynamic parameters.All the results were consistent with the theory of Brownian motion and demonstrated the feasibility of XPCS at SSRF.Finally,by carefully optimizing the setup and analyzing the algorithms,we achieved a time resolution of 2 ms,which enabled the characterization of millisecond dynamics in opaque systems.
基金supported by the National Natural Science Foundation of China(81870841 and 82171192 to X.S.L.,82101349 to G.L.Q.)。
文摘General anesthesia is widely applied in clinical practice.However,the precise mechanism of loss of consciousness induced by general anesthetics remains unknown.Here,we measured the dynamics of five neurotransmitters,includingγ-aminobutyric acid,glutamate,norepinephrine,acetylcholine,and dopamine,in the medial prefrontal cortex and primary visual cortex of C57BL/6 mice through in vivo fiber photometry and genetically encoded neurotransmitter sensors under anesthesia to reveal the mechanism of general anesthesia from a neurotransmitter perspective.Results revealed that the concentrations of γ-aminobutyric acid,glutamate,norepinephrine,and acetylcholine increased in the cortex during propofol-induced loss of consciousness.Dopamine levels did not change following the hypnotic dose of propofol but increased significantly following surgical doses of propofol anesthesia.Notably,the concentrations of the five neurotransmitters generally decreased during sevoflurane-induced loss of consciousness.Furthermore,the neurotransmitter dynamic networks were not synchronized in the non-anesthesia groups but were highly synchronized in the anesthetic groups.These findings suggest that neurotransmitter dynamic network synchronization may cause anesthetic-induced loss of consciousness.
基金supported by the National Natural Science Foundation of China (52322210, 52172144, 22375069, 21825103, and U21A2069)National Key R&D Program of China (2021YFA1200501)+2 种基金Shenzhen Science and Technology Program (JCYJ20220818102215033, JCYJ20200109105422876)the Innovation Project of Optics Valley Laboratory (OVL2023PY007)Science and Technology Commission of Shanghai Municipality (21YF1454700)。
文摘The utilization of processing capabilities within the detector holds significant promise in addressing energy consumption and latency challenges. Especially in the context of dynamic motion recognition tasks, where substantial data transfers are necessitated by the generation of extensive information and the need for frame-by-frame analysis. Herein, we present a novel approach for dynamic motion recognition, leveraging a spatial-temporal in-sensor computing system rooted in multiframe integration by employing photodetector. Our approach introduced a retinomorphic MoS_(2) photodetector device for motion detection and analysis. The device enables the generation of informative final states, nonlinearly embedding both past and present frames. Subsequent multiply-accumulate (MAC) calculations are efficiently performed as the classifier. When evaluating our devices for target detection and direction classification, we achieved an impressive recognition accuracy of 93.5%. By eliminating the need for frame-by-frame analysis, our system not only achieves high precision but also facilitates energy-efficient in-sensor computing.
基金supported by the National Natural Science Foundation of China(Grant No.12174257)the National Key R&D program of China(Grant No.2020YFA0309601)+1 种基金the Science and Technology Commission of the Shanghai Municipality(Grant No.21JC1405100)the Start-Up Grant of ShanghaiTech University。
文摘We theoretically study the charge order and orbital magnetic properties of a new type of antiferromagnetic kagome metal FeGe.Based on first-principles density functional theory calculations,we study the electronic structures,Fermi-surface quantum fluctuations,as well as phonon properties of the antiferromagnetic kagome metal FeGe.It is found that charge density wave emerges in such a system due to a subtle cooperation between electron-electron interactions and electron–phonon couplings,which gives rise to an unusual scenario of interaction-triggered phonon instabilities,and eventually yields a charge density wave(CDW)state.We further show that,in the CDW phase,the ground-state current density distribution exhibits an intriguing star-of-David pattern,leading to flux density modulation.The orbital fluxes(or current loops)in this system emerge as a result of the subtle interplay between magnetism,lattice geometries,charge order,and spin-orbit coupling(SOC),which can be described by a simple,yet universal,tight-binding theory including a Kane-Mele-type SOC term and a magnetic exchange interaction.We further study the origin of the peculiar step-edge states in FeGe,which sheds light on the topological properties and correlation effects in this new type of kagome antiferromagnetic material.
基金the financial support from the National Natural Science Foundation of China(71934004)Key Projects of the National Social Science Foundation(23AZD065)the Project of the CNOOC Energy Economics Institute(EEI-2022-IESA0009)。
文摘With the implementation of the Belt and Road Initiative, China is deepening its cooperation in oil and gas resources with countries along the Initiative. In order to better mitigate risks and enhance the safety of investments, it is of significant importance to research the oil and gas investment environment in these countries for China's overseas investment macro-layout. This paper proposes an indicator system including 27 indicators from 6 dimensions. On this basis, game theory models combined with global entropy method and analytic hierarchy process are applied to determine the combined weights, and the TOPSIS-GRA model is utilized to assess the risks of oil and gas investment in 76 countries along the Initiative from 2014 to 2021. Finally, the GM(1,1) model is employed to predict risk values for 2022-2025. In conclusion, oil and gas resources and political factors have the greatest impact on investment environment risk, and 12 countries with greater investment potential are selected through cluster analysis in conjunction with the predicted results. The research findings may provide scientific decisionmaking recommendations for the Chinese government and oil enterprises to strengthen oil and gas investment cooperation with countries along the Belt and Road Initiative.
基金supported by the Starting Foundation of ShanghaiTech Universitythe Double First-Class Initiative Fund of ShanghaiTech Universitythe National Natural Science Foundation of China (21972092)
文摘Oxynitride semiconductors are promising photocatalyst materials for visible light-driven water splitting,while the synthesis of well crystalized oxynitride still remains challenge.In present work,narrow-bandgap TaON nanoparticles are synthesized via heating a vacuum-sealed mixture of KTaO_(3),Ta and NH_(4)Cl.This method possesses multiple advantages in terms of lower calcination parameter,higher N conversion efficiency and superior photocatalytic activity in comparison with the traditional thermal ammonolysis using NH_(3) gas as a nitrogen source.Through the analysis of intermediates produced upon the elevation of heating temperature,a gas-solid-phase reaction between TaCl_(5) and Ta_(2)O_(5) is demonstrated as the final step,which is conducive to decreasing thermal energy barrier and accelerating nitridation process.Precise control of preparation conditions,including calcination temperature and duration,allows for the regulation of surface O/N ratio of TaON particles to unity,resulting in optimized photocat-alytic activity.Photoelectrochemical assessment and intensity modulated photocurrent spectroscopy provide convincing evidence for improved charge transfer effciency of photoexcited holes at TaON surface.A Z-scheme overall water splitting is accomplished by employing the TaON as an effective oxygen evolution photocatalyst,SrTiO_(3):Rh as a hydrogen evolution photocatalyst,and reduced graphene oxide(rGO)as a solid-state electron mediator.This work presents a promising strategy for the synthesis of high-quality oxynitride materials in application to photocatalytic water splitting.
基金supported by the SSRF Phase-II Beamline Project.
文摘The dynamics beamline(D-Line),which combines synchrotron radiation infrared spectroscopy(SR-IR)and energy-disper-sive X-ray absorption spectroscopy(ED-XAS),is the first beamline in the world to realize concurrent ED-XAS and SR-IR measurements at the same sample position on a millisecond time-resolved scale.This combined technique is effective for investigating rapid structural changes in atoms,electrons,and molecules in complicated disorder systems,such as those used in physics,chemistry,materials science,and extreme conditions.Moreover,ED-XAS and SR-IR can be used independently in the two branches of the D-Line.The ED-XAS branch is the first ED-XAS beamline in China,which uses a tapered undulator light source and can achieve approximately 2.5×10^(12)photons/s·300 eV BW@7.2 keV at the sample position.An exchange-able polychromator operating in the Bragg-reflection or Laue-transmission configuration is used in different energy ranges to satisfy the requirements for beam size and energy resolution.The focused beam size is approximately 3.5μm(H)×21.5μm(V),and the X-ray energy range is 5–25 keV.Using one-and two-dimensional position-sensitive detectors with frame rates of up to 400 kHz enables time resolutions of tens of microseconds to be realized.Several distinctive techniques,such as the concurrent measurement of in situ ED-XAS and infrared spectroscopy,time-resolved ED-XAS,high-pressure ED-XAS,XMCD,and pump-probe ED-XAS,can be applied to achieve different scientific goals.
基金supported by the start-up funding of ShanghaiTech University in Chinasupported by a user project at the Molecular Foundry (LBNL) and its computing resources administered by the High-Performance Computing Services Group at LBNL+2 种基金supported by the Office of Science and Office of Basic Energy Sciences of the U.S.Department of Energy (Grant No.DE-AC02-05CH11231)the National Energy Research Scientific Computing Center (NERSC),a U.S.Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory (Grant No.DE-AC02-05CH11231)supported by the High-Performance Computing (HPC) Platform of ShanghaiTech University。
文摘Fewest-switches surfacing hopping(FSSH) simulations have been performed with the high-level multi-reference electronic structure method to explore the coupled electronic and nuclear dynamics upon photoexcitation of cyanogen bromide(BrCN). The potential energy surfaces(PES) of BrCN are charted as functions of the Jacobi coordinates(R, θ). An indepth examination of the FSSH trajectories reveals the temporal dynamics of the molecule and the population changes of the lowest twelve states during BrCN's photodissociation process, which presents a rich tapestry of dynamical information.Furthermore, the carbon K-edge x-ray absorption spectroscopy(XAS) is calculated with multi-reference inner-shell spectral simulations. The rotation of the CN fragment and the elongation of the C–Br bond are found to be the reason for the peak shifting in the XAS. Our findings offer a nuanced interpretation for inner-shell probe investigations of BrCN, setting the stage for a deeper understanding of the photodissociation process of cyanogen halides molecules.
基金Project supported by the National Key Research and Development Program of China (Grant No.2022YFA1403000)the National Natural Science Foundation of China (Grant No.12374161)+3 种基金the Fund from the Science and Technology Commission of Shanghai Municipality (Grant No.21PJ410800)the support from the National Natural Science Foundation of China (Grant No.92164104)the Rising Star Program of Shanghai (Grant No.21QA1406000)the Open Fund of State Key Laboratory of Infrared Physics。
文摘Chromium tellurium compounds are important two-dimensional van der Waals ferromagnetic materials with high Curie temperature and chemical stability in air,which is promising for applications in spintronic devices.Here,highquality spin-orbital-torque(SOT)device,Bi_(2)Te_(3)/CrTe_(2)heterostructure was epitaxially grown on Al_(2)O_(3)(0001)substrates.Anomalous Hall measurements indicate the existence of strong ferromagnetism in this device with the CrTe_(2)thickness down to 10 nm.In order to investigate its micromagnetic structure,cryogenic magnetic force microscope(MFM)was utilized to measure the magnetic domain evolutions at various temperatures and magnetic fields.The virgin domain state of the device shows a worm-like magnetic domain structure with the size around 0.6μm-0.8μm.Larger irregular-shape magnetic domains(>1μm)can be induced and pinned,after the field is increased to coercive field and ramped back to low fields.The temperature-dependent MFM signals exhibit a nice mean-field-like ferromagnetic transition with Curie temperature around 201.5 K,indicating a robust ferromagnetic ordering.Such a device can be potentially implemented in future magnetic memory technology.
基金supported by the National Natural Science Foundation of China,Nos.31871039 and 32170962(to MSH).
文摘Parkinson’s disease is a progressive neurodegenerative disease characterized by motor deficits,dopaminergic neuron loss,and brain accumulation ofα-synuclein aggregates called Lewy bodies.Dysfunction in protein degradation pathways,such as autophagy,has been demonstrated in neurons as a critical mechanism for eliminating protein aggregates in Parkinson’s disease.However,it is less well understood how protein aggregates are eliminated in glia,the other cell type in the brain.In the present study,we show that autophagy-related gene 9(Atg9),the only transmembrane protein in the autophagy machinery,is highly expressed in Drosophila glia from adult brain.Results from immunostaining and live cell imaging analysis reveal that a portion of Atg9 localizes to the trans-Golgi network,autophagosomes,and lysosomes in glia.Atg9 is persistently in contact with these organelles.Lacking glial atg9 reduces the number of omegasomes and autophagosomes,and impairs autophagic substrate degradation.This suggests that glial Atg9 participates in the early steps of autophagy,and hence the control of autophagic degradation.Importantly,loss of glial atg9 induces parkinsonian symptoms in Drosophila including progressive loss of dopaminergic neurons,locomotion deficits,and glial activation.Our findings identify a functional role of Atg9 in glial autophagy and establish a potential link between glial autophagy and Parkinson’s disease.These results may provide new insights on the underlying mechanism of Parkinson’s disease.
基金supported by the National Natural Science Foundation of China(Nos.11605275 and 11675247)。
文摘In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification.The effect of the absorbed dose was investigated in the range of 5–50 kGy.NWF-serine was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,and scanning electron microscopy.Batch adsorption tests were conducted to investigate the influences of pH,adsorption time,temperature,initial concentration,and sorbent dosage on the Pb(Ⅱ) adsorption performance of NWF-serine.The results indicated that Pb(Ⅱ) adsorption onto NWF-serine was an endothermic process,following the pseudo-second-order kinetic model and Langmuir isotherm model.The saturated adsorption capacity was 198.1 mg/g.NWF-serine exhibited Pb(Ⅱ) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd,Cu,Ni,Mn,and Zn.Furthermore,NWF-serine maintained 86% of its Pb(Ⅱ) uptake after five use cycles.The coordination of the carboxyl and amino groups with Pb(Ⅱ) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.
基金financial support from the National Natural Science Foundation of China (Grant No. 12227901)the financial support from the National Natural Science Foundation of China (Grant Nos. 11974263 and 12174291)。
文摘We report a linear-scaling random Green's function(rGF) method for large-scale electronic structure calculation. In this method, the rGF is defined on a set of random states and is efficiently calculated by projecting onto Krylov subspace. With the rGF method, the Fermi–Dirac operator can be obtained directly, avoiding the polynomial expansion to Fermi–Dirac function. To demonstrate the applicability, we implement the rGF method with the density-functional tight-binding method. It is shown that the Krylov subspace can maintain at small size for materials with different gaps at zero temperature, including H_(2)O and Si clusters. We find with a simple deflation technique that the rGF self-consistent calculation of H_(2)O clusters at T = 0 K can reach an error of~ 1 me V per H_(2)O molecule in total energy, compared to deterministic calculations. The rGF method provides an effective stochastic method for large-scale electronic structure simulation.
基金supported by the National Natural Science Foundation of China (Grant No. 52272265)the National Key R&D Program of China (Grant Nos. 2023YFA1607400 and 2018YFA0704300)+4 种基金the support from the National Natural Science Foundation of China (Grant Nos. 52271016 and 52188101)the support from Analytical Instrumentation Center (# SPST-AIC10112914), SPST, Shanghai Tech Universitythe European Research Council (ERC Advanced Grant No. 742068 ‘TOPMAT’)the DFG through SFB 1143 (Project ID 247310070)the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter ct.qmat (EXC2147,Project ID 390858490)。
文摘Recently, giant intrinsic anomalous Hall effect(AHE) has been observed in the materials with kagome lattice.Here, we systematically investigate the influence of high pressure on the AHE in the ferromagnet LiMn_(6)Sn_(6) with clean Mn kagome lattice. Our in situ high-pressure Raman spectroscopy indicates that the crystal structure of LiMn_(6)Sn_(6) maintains a hexagonal phase under high pressures up to 8.51 GPa. The anomalous Hall conductivity(AHC) σ_(xy)^(A) remains around 150 Ω^(-1)·cm^(-1), dominated by the intrinsic mechanism. Combined with theoretical calculations, our results indicate that the stable AHE under pressure in Li Mn_(6)Sn_(6) originates from the robust electronic and magnetic structure.
基金Project supported by the National Key R&D Program of China (Grant Nos. 2022YFA1604402 and 2022YFA1604403)the National Natural Science Foundation of China (NSFC) (Grant No. 11721404)+3 种基金the Shanghai Rising-Star Program (Grant No. 21QA1406100)the Technology Innovation Action Plan of the Science and Technology Commission of Shanghai Municipality (Grant No. 20JC1416000)support by the Air Force Office of Scientific Research (AFOSR) (Grant No. FA9550-20-10139)the Texas A&M Engineering Experimental Station (TEES)
文摘With the integration of ultrafast reflectivity and polarimetry probes,we observed carrier relaxation and spin dynamics induced by ultrafast laser excitation of Ni(111)single crystals.The carrier relaxation time within the linear excitation range reveals that electron-phonon coupling and dissipation of photon energy into the bulk of the crystal take tens of picoseconds.On the other hand,the observed spin dynamics indicate a longer time of about 120 ps.To further understand how the lattice degree of freedom is coupled with these dynamics may require the integration of an ultrafast diffraction probe.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12004405,12334008,and 12374148)the Double First-Class Initiative Fund of Shanghai Tech University+2 种基金the Analytical Instrumentation Center of Shanghai Tech University(Grant No.SPST-AIC10112914)the research fund from the Shanghai Sailing Program(Grant No.23YF1426900)the fund from the National Key R&D Program of China(Grant Nos.2022YFA1402702 and 2021YFA1401600)。
文摘The REAgSb_(2)(RE = rare earth and Y) family has drawn considerable research interest because the two-dimensional Sb net in their crystal structures hosts topological fermions and hence rich topological properties. We report herein the magnetization and magnetotransport measurements of SmAgSb_(2) single crystal, which unveil very large magnetoresistance and high carrier mobility up to 6.2 × 10^(3)% and 5.58 × 10^(3)cm^(2)·V^(-1)·s^(-1), respectively. The analysis of both Shubnikov–de Haas and de Haas–van Alphen quantum oscillations indicates nontrivial Berry phases in the paramagnetic state while trivial Berry curvature in the antiferromagnetic state, indicating a topological phase transition induced by the antiferromagnetic order. It is also supported by the first-principles calculations. The results not only provide a new interesting topological material but also offer valuable insights into the correlation between magnetism and nontrivial topological states.
基金This work was supported by National Natural Science Foundation of China(No.12222513).
文摘Radio frequency quadrupoles(RFQs),which are crucial components of proton injectors,significantly affect the performance of proton accelerator facilities.An RFQ with a high frequency of 714 MHz dedicated to compact proton injectors for medi-cal applications is designed in this study.The RFQ is designed to accelerate proton beams from 50 keV to 4 MeV within a short length of 2 m and can be matched closely with the downstream drift tube linac to capture more particles through a preliminary optimization.To develop an advanced RFQ,challenging techniques,including fabrication and tuning method,must be evaluated and verified using a prototype.An aluminium prototype is derived from the conceptual design of the RFQ and then redesigned to confirm the radio frequency performance,fabrication procedure,and feasibility of the tuning algorithm.Eventually,a new tuning algorithm based on the response matrix and least-squares method is developed,which yields favorable results based on the prototype,i.e.,the errors of the dipole and quadrupole components reduced to a low level after several tuning iterations.Benefiting from the conceptual design and techniques obtained from the prototype,the formal mechanical design of the 2-m RFQ is ready for the next manufacturing step.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1604302)the National Natural Science Foundation of China(Grant Nos.U1632266,11927807,and U2032207)the approval of the Proposal Assessing Committee of SiP.ME^(2) platform project(Proposal No.11227902)supported by the National Science Foundation of China。
文摘Magnetic topological semimetals have been at the forefront of condensed matter physics due to their ability to exhibit exotic transport phenomena.Investigating the interplay between magnetic and topological orders in systems with broken time-reversal symmetry is crucial for realizing non-trivial quantum effects.We delve into the electronic structure of the rare-earth-based antiferromagnetic Dirac semimetal EuMg_(2)Bi_(2) using first-principles calculations and angle-resolved photoemission spectroscopy.Our calculations reveal that the spin-orbit coupling(SOC)in EuMg_(2)Bi_(2) prompts an insulator to topological semimetal transition,with the Dirac bands protected by crystal symmetries.The linearly dispersive states near the Fermi level,primarily originating from Bi 6p orbitals,are observed on both the(001)and(100)surfaces,confirming that EuMg_(2)Bi_(2) is a three-dimensional topological Dirac semimetal.This research offers pivotal insights into the interplay between magnetism,SOC and topological phase transitions in spintronics applications.
基金supported by ShanghaiTech University Startup Fund 2017F0203-000-14the National Natural Science Foundation of China(Grant No.52131303)+1 种基金Natural Science Foundation of Shanghai(Grant No.22ZR1442300)in part by CAS Strategic Science and Technology Program(Grant No.XDA18000000).
文摘Emission and capture characteristics of a deep hole trap(H1)in n-GaN Schottky barrier diodes(SBDs)have been investigated by optical deep level transient spectroscopy(ODLTS).Activation energy(Eemi)and capture cross-section(σ_(p))of H1 are determined to be 0.75 eV and 4.67×10^(−15)cm^(2),respectively.Distribution of apparent trap concentration in space charge region is demonstrated.Temperature-enhanced emission process is revealed by decrease of emission time constant.Electricfield-boosted trap emission kinetics are analyzed by the Poole−Frenkel emission(PFE)model.In addition,H1 shows point defect capture properties and temperature-enhanced capture kinetics.Taking both hole capture and emission processes into account during laser beam incidence,H1 features a trap concentration of 2.67×10^(15)cm^(−3).The method and obtained results may facilitate understanding of minority carrier trap properties in wide bandgap semiconductor material and can be applied for device reliability assessment.
基金National Natural Science Foundation of China(No.12205360)Shanghai Pilot Program for Basic Research-Chinese Academy of Science,Shanghai Branch(No.JCYJ-SHFY-2021-010).
文摘This study presents a new method for characterizing the thermal lattice deformation of a monochromator with high precision under service conditions and first reports the operando measurements of nanoscale thermal lattice deformation on a double-crystal monochromator at different incident powers.The nanoscale thermal lattice deformation of the monochromator first crystal was obtained by analyzing the intensity of the distorted DuMond diagrams.DuMond diagrams of the 333 diffraction index,sensitive to lattice deformation,were obtained directly using a 2D detector and an analyzer crystal orthogonal to the monochromator.With increasing incident power and power density,the maximum height of the lattice deformation increased from 3.2 to 18.5 nm,and the deformation coefficient of the maximum height increased from 1.1 to 3.2 nm/W.The maximum relative standard deviation was 4.2%,and the maximum standard deviation was 0.1 nm.Based on the measured thermal deformations,the flux saturation phenomenon and critical point for the linear operation of the monochromator were predicted with increasing incident power.This study provides a simple solution to the problem of the lower precision of synchrotron radiation monochromator characterizations compared to simulations.