Spinal cord injury is an intractable traumatic injury. The most common hurdles faced during spinal cord injury are failure of axonal regrowth and reconnection to target sites. These also tend to be the most challengin...Spinal cord injury is an intractable traumatic injury. The most common hurdles faced during spinal cord injury are failure of axonal regrowth and reconnection to target sites. These also tend to be the most challenging issues in spinal cord injury. As spinal cord injury progresses to the chronic phase, lost motor and sensory functions are not recovered. Several reasons may be attributed to the failure of recovery from chronic spinal cord injury. These include factors that inhibit axonal growth such as activated astrocytes, chondroitin sulfate proteoglycan, myelin-associated proteins, inflammatory microglia, and fibroblasts that accumulate at lesion sites. Skeletal muscle atrophy due to denervation is another chronic and detrimental spinal cord injury–specific condition. Although several intervention strategies based on multiple outlooks have been attempted for treating spinal cord injury, few approaches have been successful. To treat chronic spinal cord injury, neural cells or tissue substitutes may need to be supplied in the cavity area to enable possible axonal growth. Additionally, stimulating axonal growth activity by extrinsic factors is extremely important and essential for maintaining the remaining host neurons and transplanted neurons. This review focuses on pharmacotherapeutic approaches using small compounds and proteins to enable axonal growth in chronic spinal cord injury. This review presents some of these candidates that have shown promising outcomes in basic research(in vivo animal studies) and clinical trials: AA-NgR(310)ecto-Fc(AXER-204), fasudil, phosphatase and tensin homolog protein antagonist peptide 4, chondroitinase ABC, intracellular sigma peptide,(-)-epigallocatechin gallate, matrine, acteoside, pyrvate kinase M2, diosgenin, granulocyte-colony stimulating factor, and fampridine-sustained release. Although the current situation suggests that drug-based therapies to recover function in chronic spinal cord injury are limited, potential candidates have been identified through basic research, and these candidates may be subjects of clinical studies in the future. Moreover, cocktail therapy comprising drugs with varied underlying mechanisms may be effective in treating the refractory status of chronic spinal cord injury.展开更多
Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significan...Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significant challenging in regulating local phase evolution.Herein,accordion-shaped Co/Co_(3)O_(4)@N-doped carbon nanosheets(Co/Co_(3)O_(4)@NC)with gradient magnetic heterointerfaces have been fabricated via the cooperative high-temperature carbonization and lowtemperature oxidation process.The results indicate that the surface epitaxial growth of crystal Co_(3)O_(4) domains on local Co nanoparticles realizes the adjustment of magnetic-heteroatomic components,which are beneficial for optimizing impedance matching and interfacial polarization.Moreover,gradient magnetic heterointerfaces simultaneously realize magnetic coupling,and long-range magnetic diffraction.Specifically,the synthesized Co/Co_(3)O_(4)@NC absorbents display the strong electromagnetic wave attenuation capability of−53.5 dB at a thickness of 3.0 mm with an effective absorption bandwidth of 5.36 GHz,both are superior to those of single magnetic domains embedded in carbon matrix.This design concept provides us an inspiration in optimizing interfacial polarization,regulating magnetic coupling and promoting electromagnetic wave absorption.展开更多
We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) change...We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) changed from 0.5:1 to 4:1,and the impregnation time changed from 1 to 7 h.The typical composite phase change thermal storage materials doped with the as-treated graphite were fabricated using form-stable technique.To investigate the oxidation and anti-oxidation behavior of the impregnated graphite at high temperatures,the samples were put into a muffle furnace for a cyclic heat test.Based on SEM,EDS,DSC techniques,analyses on the impregnated technique suggested an optimized processing conditions of a 3 h impregnation time with the ratio of graphite:Al(H_(2)PO_(4))_(3) as 1:3 for graphite impregnation treatment.Further investigations on high-temperature phase change heat storage materials doped by the treated graphite suggested excellent oxidation resistance and thermal cycling performance.展开更多
As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding...As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding scenarios.This paper discusses interferogram modeling and phase distortion cor-rection techniques for spaceborne DASH interferometers.The modeling of phase distortion interferograms with and without Doppler shift for limb observation was conducted,and the effectiveness of the analytical expression was verified through numerical simulation.The simulation results indicate that errors propagate layer by layer while using the onion-peeling inversion algorithm to handle phase-distorted interferograms.In contrast,the phase distortion correction algorithm can achieve effective correction.This phase correction method can be successfully applied to correct phase distortions in the interferograms of the spaceborne DASH interferometer,providing a feasible solution to enhance its measurement accuracy.展开更多
In the energy industry landscape,thermal power generation stands as a critical energy supply method,and the safety of its construction and operation is paramount.Currently,all stages of the life cycle of construction ...In the energy industry landscape,thermal power generation stands as a critical energy supply method,and the safety of its construction and operation is paramount.Currently,all stages of the life cycle of construction projects have garnered widespread attention.Among these,the infrastructure construction and operation phases of thermal power generation enterprises pose numerous issues worthy of in-depth study in terms of safety production management.This article starts by examining safety production management during these two phases,analyzing characteristics such as management models,legal bases,and responsible entities.It explores the reasons behind these characteristics and elaborates on key management priorities,providing a comprehensive and insightful reference for safety production management in thermal power generation enterprises.展开更多
The equilibrium phase relations of the CaO–SiO_(2)–TiO_(2)–5wt%Fe_(3)O_(4)system were experimentally investigated at 1400℃ in air High-temperature equilibration-quenching techniques were employed in an electric Mo...The equilibrium phase relations of the CaO–SiO_(2)–TiO_(2)–5wt%Fe_(3)O_(4)system were experimentally investigated at 1400℃ in air High-temperature equilibration-quenching techniques were employed in an electric MoSi2resistance heated furnace,with phase composition analysis conducted using an electron probe microanalyzer and X-ray diffraction.A single liquid region,liquid–solid phase equilibria regions (including liquid–tridymite,liquid–rutile,liquid–perovskite,and liquid–wollastonite),and three-phase equilibria regions of liquid–tridymite–rutile and liquid–rutile–perovskite were found.The 1400℃ isothermal sections of the CaO-SiO_(2)-TiO_(2)-5wt%Fe_(3)O_(4)system in air were projected.The present experimental results exhibited good agreement with the calculation results obtained from FactSage.展开更多
Comprehensive understanding of the direct transformation pathway from graphite to diamond under high temperature and high pressure has long been one of the fundamental goals in materials science.Despite considerable e...Comprehensive understanding of the direct transformation pathway from graphite to diamond under high temperature and high pressure has long been one of the fundamental goals in materials science.Despite considerable experimental and theoretical progress,current experimental studies have mainly focused on the local microstructural characterizations of recovered samples,which has certain limitations for hightemperature and high-pressure products,which often exhibit diversity.Here,we report on the pressure-induced phase transition behavior of natural single-crystal graphite under three distinct pressure-transmitting media from a macroscopic perspective using in situ two-dimensional Raman spectroscopy,scanning electron microscopy,and atomic force microscopy.The surface evolution process of graphite before and after the phase transition is captured,revealing that pressure-induced surface textures can impede the continuity of the phase transition process across the entire single crystal.Our results provide a fresh perspective for studying the phase transition behavior of graphite and greatly deepen our understanding of this behavior,which will be helpful in guiding further high-temperature and high-pressure syntheses of carbon allotropes.展开更多
Understanding the evolution of microstructures in nuclear fuels under high-burn-up conditions is critical for extending fuel refueling cycles and enhancing nuclear reactor safety.In this study,a phase-field model is p...Understanding the evolution of microstructures in nuclear fuels under high-burn-up conditions is critical for extending fuel refueling cycles and enhancing nuclear reactor safety.In this study,a phase-field model is proposed to examine the evolution of high-burn-up structures in polycrystalline UO_(2).The formation and growth of recrystallized grains were initially investigated.It was demonstrated that recrystallization kinetics adhere to the Kolmogorov–Johnson–Mehl–Avrami(KJMA)equation,and that recrystallization represents a process of free-energy reduction.Subsequently,the microstructural evolution in UO_(2) was analyzed as the burn up increased.Gas bubbles acted as additional nucleation sites,thereby augmenting the recrystallization kinetics,whereas the presence of recrystallized grains accelerated bubble growth by increasing the number of grain boundaries.The observed variations in the recrystallization kinetics and porosity with burn-up closely align with experimental findings.Furthermore,the influence of grain size on microstructure evolution was investigated.Larger grain sizes were found to decrease porosity and the occurrence of high-burn-up structures.展开更多
The research,fabrication and development of piezoelectric nanofibrous materials offer effective solutions to the challenges related to energy consumption and non-renewable resources.However,enhancing their electrical ...The research,fabrication and development of piezoelectric nanofibrous materials offer effective solutions to the challenges related to energy consumption and non-renewable resources.However,enhancing their electrical output still remains a significant challenge.Here,a strategy of inducing constrained phase separation on single nanofibers via shear force was proposed.Employing electrospinning technology,a polyacrylonitrile/polyvinylidene difluoride(PAN/PVDF)nanofibrous membrane was fabricated in one step,which enabled simultaneous piezoelectric and triboelectric conversion within a single-layer membrane.Each nanofiber contained independent components of PAN and PVDF and exhibited a rough surface.The abundant frictional contact points formed between these heterogeneous components contributed to an enhanced endogenous triboelectric output,showcasing an excellent synergistic effect of piezoelectric and triboelectric response in the nanofibrous membrane.Additionally,the component mass ratio influenced the microstructure,piezoelectric conformation and piezoelectric performance of the PAN/PVDF nanofibrous membranes.Through comprehensive performance comparison,the optimal mass ratio of PAN to PVDF was determined to be 9∶1.The piezoelectric devices made of the optimal PAN/PVDF nanofibrous membranes with rough nanofiber surfaces generated an output voltage of 20 V,which was about 1.8 times that of the smooth one at the same component mass ratio.The strategy of constrained phase separation on the surface of individual nanofibers provides a new approach to enhance the output performance of single-layer piezoelectric nanofibrous materials.展开更多
Bird vocalizations are pivotal for ecological monitoring,providing insights into biodiversity and ecosystem health.Traditional recognition methods often neglect phase information,resulting in incomplete feature repres...Bird vocalizations are pivotal for ecological monitoring,providing insights into biodiversity and ecosystem health.Traditional recognition methods often neglect phase information,resulting in incomplete feature representation.In this paper,we introduce a novel approach to bird vocalization recognition(BVR)that integrates both amplitude and phase information,leading to enhanced species identification.We propose MHARes Net,a deep learning(DL)model that employs residual blocks and a multi-head attention mechanism to capture salient features from logarithmic power(POW),Instantaneous Frequency(IF),and Group Delay(GD)extracted from bird vocalizations.Experiments on three bird vocalization datasets demonstrate our method's superior performance,achieving accuracy rates of 94%,98.9%,and 87.1%respectively.These results indicate that our approach provides a more effective representation of bird vocalizations,outperforming existing methods.This integration of phase information in BVR is innovative and significantly advances the field of automatic bird monitoring technology,offering valuable tools for ecological research and conservation efforts.展开更多
Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effec...Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effective Hamiltonian method in conjuction with the phase-field model, we have successfully reproduced the thermal hysteresis observed in ferroelectric materials during phase transitions. The computational results regarding the electrocaloric effect from these two different computational scales closely align with experimental measurements. Furthermore, we analyze how the first-order ferroelectric phase transition gradually diminishes with an increasing applied electric field, exhibiting characteristics of second-order-like phase transition. By employing the characteristic parameters of thermal hysteresis, we have established a pathway for calculations across different computational scales, thereby providing theoretical support for further investigations into the properties of ferroelectric materials through concurrent multiscale simulations.展开更多
In x-ray dark-field imaging using dual phase grating interferometer,multi-contrast signals are extracted from a set of acquired phase-stepping data by using the least-squares fitting algorithm.The extracted mean inten...In x-ray dark-field imaging using dual phase grating interferometer,multi-contrast signals are extracted from a set of acquired phase-stepping data by using the least-squares fitting algorithm.The extracted mean intensity,amplitude and visibility signals may be intrinsically biased.However,it is still unclear how large these biases are and how the data acquisition parameters influence the biases in the extracted signals.This work set out to address these questions.Analytical expressions of the biases of the extracted signals were theoretically derived by using a second-order Taylor series expansion.Extensive numerical simulations were performed to validate the theoretical results.It is illustrated that while the estimated mean intensity signal is always unbiased,the estimated amplitude and visibility signals are both positively biased.While the biases of the estimated amplitude signals are proportional to the inverse of the total number of phase steps,the biases of the estimated visibility signals are inversely proportional to the product of the total number of phase steps and the mean number of photons counted per phase step.Meanwhile,it is demonstrated that the dependence of the biases on the mean visibility is quite different from that of Talbot-Lau interferometer due to the difference in the intensity model.We expect that these results can be useful for data acquisition optimizations and interpretation of x-ray dark-field images.展开更多
Two-dimensional(2D)moirésuperlattices with a small twist in orientation exhibit a broad range of physical properties due to the complicated intralayer and interlayer interactions modulated by the twist angle.Here...Two-dimensional(2D)moirésuperlattices with a small twist in orientation exhibit a broad range of physical properties due to the complicated intralayer and interlayer interactions modulated by the twist angle.Here,we report a metal-semiconductor phase transition in homojunction moirésuperlattices of NiS_2 and PtTe_2 with large twist angles based on high-throughput screening of 2D materials MX_(2)(M=Ni,Pd,Pt;X=S,Se,Te)via density functional theory(DFT)calculations.Firstly,the calculations for different stacking configurations(AA,AB and AC)reveal that AA stacking ones are stable for all the bilayer MX_(2).The metallic or semiconducting properties of these 2D materials remain invariable for different stacking without twisting except for NiS_2 and PtTe_2.For the twisted configurations,NiS_2 transfers from metal to semiconductor when the twist angles are 21.79°,27.79°,32.20°and 60°.PtTe_2 exhibits a similar transition at 60°.The phase transition is due to the weakened d-p orbital hybridization around the Fermi level as the interlayer distance increases in the twisted configurations.Further calculations of untwisted bilayers with increasing interlayer distance demonstrate that all the materials undergo metal-semiconductor phase transition with the increased interlayer distance because of the weakened d-p orbital hybridization.These findings provide fundamental insights into tuning the electronic properties of moirésuperlattices with large twist angles.展开更多
Rapid advances in thermal management technology and the increasing need for multi-energy conversion have placed stringent energy efficiency requirements on next-generation shape-stable composite phase change materials...Rapid advances in thermal management technology and the increasing need for multi-energy conversion have placed stringent energy efficiency requirements on next-generation shape-stable composite phase change materials(PCMs).Magnetically-responsive phase change thermal storage materials are considered an emerging concept for energy storage systems,enabling PCMs to perform unprecedented functions(such as green energy utilization,magnetic thermotherapy,drug release,etc.).The combination of multifunctional magnetic nanomaterials and PCMs is a milestone in the creation of advanced multifunctional composite PCMs.However,a timely and comprehensive review of composite PCMs based on magnetic nanoparticle modification is still missing.Herein,we furnish an exhaustive exposition elucidating the cutting-edge advancements in magnetically responsive composite PCMs.We delve deeply into the multifarious roles assumed by distinct nanoparticles within composite PCMs of varying dimensions,meticulously scrutinizing the intricate interplay between their architectures and thermophysical attributes.Moreover,we prognosticate future research trajectories,delineate alternative stratagems,and illuminate prospective avenues.This review is intended to stimulate broader academic interest in interdisciplinary fields and provide valuable insights into the development of next-generation magnetically-responsive composite PCMs.展开更多
In this study,we investigate the critical phenomena of Kerr-AdS black holes under the modified first law of thermodynamics.Specifically,we considered modified black hole thermodynamics that exhibit a van der Waalslike...In this study,we investigate the critical phenomena of Kerr-AdS black holes under the modified first law of thermodynamics.Specifically,we considered modified black hole thermodynamics that exhibit a van der Waalslike phase structure.All critical exponents were calculated,and then,a swallowtail diagram of free energy was plotted.Comparing with existing results,the main difference is the correspondence between the thermal quantities of Kerr-AdS black holes and the van der Waals system.In a previous study[Y.D.Tsai,X.N.Wu,and Y.Yang,Phys.Rev.D 85044005(2012)],the correspondence was(Ω_(H),J)→(V,P),while in our study,the correspondence was(J,Ω_(H))→(V,P).This difference was owing to the rotating effect.The modified black hole thermodynamics were associated with rotating observers.The free energy in such a reference contains extra rotating energy,which induces a Legendre transformation in the(Ω_(H),J)cross-section,causing the difference in correspondence.展开更多
Microstructural characterization,mass loss tests,hydrogen evolution tests,electrochemical measurements,and corrosion morphology observations were conducted to investigate the effect of the secondary phases on the corr...Microstructural characterization,mass loss tests,hydrogen evolution tests,electrochemical measurements,and corrosion morphology observations were conducted to investigate the effect of the secondary phases on the corrosion behavior of the as-cast Mg−7Sn−1Zn−1Y(TZW711)alloy after solution treatment(T4)and aging treatment(T6).The results show that the T4-TZW711 alloy possesses the highest corrosion resistance in the early corrosion stage.This is because the dissolution of Mg2Sn reduces the cathodic current density and increases the charge transfer resistance(Rct).When the corrosion time is prolonged,the undissolved and clustered MgSnY phase will peel off from the T4-TZW711 alloy surface,thereby increasing the corrosion rate of the alloy.After aging treatment,the undissolved MgSnY phase is dispersed,which results in a lower localized corrosion sensitivity of T6-TZW711 alloy than that of the T4-TZW711 alloy,suggesting that the T6 treatment can enhance the corrosion resistance of Mg−7Sn−1Zn−1Y alloys.展开更多
Reversible solid oxide cells(RSOCs)are capable of converting various energy resources,between electricity and chemical fuels,with high efficiency and flexibility,making them suitable for grid balancing and renewable e...Reversible solid oxide cells(RSOCs)are capable of converting various energy resources,between electricity and chemical fuels,with high efficiency and flexibility,making them suitable for grid balancing and renewable energy consumption.However,the practical application of RSOCs is still limited by the insufficient activity and stability of the electrodes in different operating modes.Herein,a highly efficient symmetrical electrode composed of La_(0.3)Sr_(0.6)Ti_(0.1)Co_(0.2)Fe_(0.7)O_(3-δ)(LSTCF)nanofibers and in situ exsolved Co_(3)Fe_(7) nanoparticles is developed for boosting the performance of RSOCs.The reversible phase transition,high activity and stability of the electrode have been confirmed by a combination of experimental(e.g.,transmission electron microscopy and X-ray absorption fine structure)and computational studies.Electrolyte-supported RSOCs with the symmetrical electrode demonstrate excellent catalytic activity and stability,achieving a high peak power density of 0.98 W cm^(-2)in the fuel cell mode using H_(2)as the fuel(or 0.53 W cm^(-2)using CH_(4)as the fuel)and a high current density of 1.09 A cm^(-2) at 1.4 V in the CO_(2)electrolysis mode(or 1.03 A cm^(-2)at 1.3 V for H_(2)O electrolysis)at 800℃while maintaining excellent durability for over 100 h.展开更多
The mechanical,thermodynamic properties and electrical conductivities of L1_(2)-Al_(3)X(X=Zr,Sc,Er,Yb,Hf)structural phases in aluminum conductors were investigated through a first-principles study.The results demonstr...The mechanical,thermodynamic properties and electrical conductivities of L1_(2)-Al_(3)X(X=Zr,Sc,Er,Yb,Hf)structural phases in aluminum conductors were investigated through a first-principles study.The results demonstrate that all structural phases have good alloy-forming ability and structural stability,where Al_(3)Zr is the most superior.Al_(3)Zr,Al_(3)Hf and Al_(3)Sc have enhanced shear and deformation resistance in comparison to other phases.Within the temperature range of 200−600 K,Al_(3)Er and Al_(3)Yb possess the greatest thermodynamic stability,followed by Al_(3)Hf,Al_(3)Zr and Al_(3)Sc.Al_(3)Er and Al_(3)Yb have higher thermodynamic stability than Al_(3)Hf,Al_(3)Zr and Al_(3)Sc.All structural phases exhibit substantial metallic properties,indicating their good electrical conductivity.The electrical conductivities of Al_(3)Hf and Al_(3)Zr are higher than those of Al_(3)Er,Al_(3)Yb and Al_(3)Sc.The covalent bond properties in Al_(3)Sc,Al_(3)Er and Al_(3)Yb enhance the hardness,brittleness and thermodynamic stability of the structural phase.The thermodynamic stability of Al_(3)Sc is significantly reduced by ionic bonds.展开更多
文摘Spinal cord injury is an intractable traumatic injury. The most common hurdles faced during spinal cord injury are failure of axonal regrowth and reconnection to target sites. These also tend to be the most challenging issues in spinal cord injury. As spinal cord injury progresses to the chronic phase, lost motor and sensory functions are not recovered. Several reasons may be attributed to the failure of recovery from chronic spinal cord injury. These include factors that inhibit axonal growth such as activated astrocytes, chondroitin sulfate proteoglycan, myelin-associated proteins, inflammatory microglia, and fibroblasts that accumulate at lesion sites. Skeletal muscle atrophy due to denervation is another chronic and detrimental spinal cord injury–specific condition. Although several intervention strategies based on multiple outlooks have been attempted for treating spinal cord injury, few approaches have been successful. To treat chronic spinal cord injury, neural cells or tissue substitutes may need to be supplied in the cavity area to enable possible axonal growth. Additionally, stimulating axonal growth activity by extrinsic factors is extremely important and essential for maintaining the remaining host neurons and transplanted neurons. This review focuses on pharmacotherapeutic approaches using small compounds and proteins to enable axonal growth in chronic spinal cord injury. This review presents some of these candidates that have shown promising outcomes in basic research(in vivo animal studies) and clinical trials: AA-NgR(310)ecto-Fc(AXER-204), fasudil, phosphatase and tensin homolog protein antagonist peptide 4, chondroitinase ABC, intracellular sigma peptide,(-)-epigallocatechin gallate, matrine, acteoside, pyrvate kinase M2, diosgenin, granulocyte-colony stimulating factor, and fampridine-sustained release. Although the current situation suggests that drug-based therapies to recover function in chronic spinal cord injury are limited, potential candidates have been identified through basic research, and these candidates may be subjects of clinical studies in the future. Moreover, cocktail therapy comprising drugs with varied underlying mechanisms may be effective in treating the refractory status of chronic spinal cord injury.
基金financially supported by the National Natural Science Foundation of China(52373271)Science,Technology and Innovation Commission of Shenzhen Municipality under Grant(KCXFZ20201221173004012)+1 种基金National Key Research and Development Program of Shaanxi Province(No.2023-YBNY-271)Open Testing Foundation of the Analytical&Testing Center of Northwestern Polytechnical University(2023T019).
文摘Gradient magnetic heterointerfaces have injected infinite vitality in optimizing impedance matching,adjusting dielectric/magnetic resonance and promoting electromagnetic(EM)wave absorption,but still exist a significant challenging in regulating local phase evolution.Herein,accordion-shaped Co/Co_(3)O_(4)@N-doped carbon nanosheets(Co/Co_(3)O_(4)@NC)with gradient magnetic heterointerfaces have been fabricated via the cooperative high-temperature carbonization and lowtemperature oxidation process.The results indicate that the surface epitaxial growth of crystal Co_(3)O_(4) domains on local Co nanoparticles realizes the adjustment of magnetic-heteroatomic components,which are beneficial for optimizing impedance matching and interfacial polarization.Moreover,gradient magnetic heterointerfaces simultaneously realize magnetic coupling,and long-range magnetic diffraction.Specifically,the synthesized Co/Co_(3)O_(4)@NC absorbents display the strong electromagnetic wave attenuation capability of−53.5 dB at a thickness of 3.0 mm with an effective absorption bandwidth of 5.36 GHz,both are superior to those of single magnetic domains embedded in carbon matrix.This design concept provides us an inspiration in optimizing interfacial polarization,regulating magnetic coupling and promoting electromagnetic wave absorption.
基金Funded by Scientific and Technological Innovation Project of Carbon Emission Peak and Carbon Neutrality of Jiangsu Province(No.BE2022028-4)。
文摘We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) changed from 0.5:1 to 4:1,and the impregnation time changed from 1 to 7 h.The typical composite phase change thermal storage materials doped with the as-treated graphite were fabricated using form-stable technique.To investigate the oxidation and anti-oxidation behavior of the impregnated graphite at high temperatures,the samples were put into a muffle furnace for a cyclic heat test.Based on SEM,EDS,DSC techniques,analyses on the impregnated technique suggested an optimized processing conditions of a 3 h impregnation time with the ratio of graphite:Al(H_(2)PO_(4))_(3) as 1:3 for graphite impregnation treatment.Further investigations on high-temperature phase change heat storage materials doped by the treated graphite suggested excellent oxidation resistance and thermal cycling performance.
文摘As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding scenarios.This paper discusses interferogram modeling and phase distortion cor-rection techniques for spaceborne DASH interferometers.The modeling of phase distortion interferograms with and without Doppler shift for limb observation was conducted,and the effectiveness of the analytical expression was verified through numerical simulation.The simulation results indicate that errors propagate layer by layer while using the onion-peeling inversion algorithm to handle phase-distorted interferograms.In contrast,the phase distortion correction algorithm can achieve effective correction.This phase correction method can be successfully applied to correct phase distortions in the interferograms of the spaceborne DASH interferometer,providing a feasible solution to enhance its measurement accuracy.
文摘In the energy industry landscape,thermal power generation stands as a critical energy supply method,and the safety of its construction and operation is paramount.Currently,all stages of the life cycle of construction projects have garnered widespread attention.Among these,the infrastructure construction and operation phases of thermal power generation enterprises pose numerous issues worthy of in-depth study in terms of safety production management.This article starts by examining safety production management during these two phases,analyzing characteristics such as management models,legal bases,and responsible entities.It explores the reasons behind these characteristics and elaborates on key management priorities,providing a comprehensive and insightful reference for safety production management in thermal power generation enterprises.
基金financially supported from the National Natural Science Foundation of China (No. 52204310)the National Key Research and Development Program of China (No. 2021YFC2901000)+4 种基金the China Postdoctoral Science Foundation (Nos. 2020TQ0059 and 2020M570967)the Natural Science Foundation of Liaoning Province, China (No. 2021-MS-083)the Fundamental Research Funds for the Central Universities, China (No. N2125010)the Open Project Program of Key Laboratory of Metallurgical Emission Reduction & Resources Recycling (Anhui University of Technology), Ministry of Education, China (No. JKF22-02)the Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, China。
文摘The equilibrium phase relations of the CaO–SiO_(2)–TiO_(2)–5wt%Fe_(3)O_(4)system were experimentally investigated at 1400℃ in air High-temperature equilibration-quenching techniques were employed in an electric MoSi2resistance heated furnace,with phase composition analysis conducted using an electron probe microanalyzer and X-ray diffraction.A single liquid region,liquid–solid phase equilibria regions (including liquid–tridymite,liquid–rutile,liquid–perovskite,and liquid–wollastonite),and three-phase equilibria regions of liquid–tridymite–rutile and liquid–rutile–perovskite were found.The 1400℃ isothermal sections of the CaO-SiO_(2)-TiO_(2)-5wt%Fe_(3)O_(4)system in air were projected.The present experimental results exhibited good agreement with the calculation results obtained from FactSage.
基金support from the National Science Fund for Distinguished Young Scholars(Grant No.T2225027)the NSAF(Grant No.U1930401)+1 种基金the National Key R&D Program of China(MOST)(Grant No.2023YFA1406500)the National Natural Science Foundation of China(NSFC)(Grant No.61674045).
文摘Comprehensive understanding of the direct transformation pathway from graphite to diamond under high temperature and high pressure has long been one of the fundamental goals in materials science.Despite considerable experimental and theoretical progress,current experimental studies have mainly focused on the local microstructural characterizations of recovered samples,which has certain limitations for hightemperature and high-pressure products,which often exhibit diversity.Here,we report on the pressure-induced phase transition behavior of natural single-crystal graphite under three distinct pressure-transmitting media from a macroscopic perspective using in situ two-dimensional Raman spectroscopy,scanning electron microscopy,and atomic force microscopy.The surface evolution process of graphite before and after the phase transition is captured,revealing that pressure-induced surface textures can impede the continuity of the phase transition process across the entire single crystal.Our results provide a fresh perspective for studying the phase transition behavior of graphite and greatly deepen our understanding of this behavior,which will be helpful in guiding further high-temperature and high-pressure syntheses of carbon allotropes.
基金supported by the National Natural Science Foundation of China(Grant Nos.U20B2013 and 12205286)the National Key Research and Development Program of China(Grant No.2022YFB1902401)。
文摘Understanding the evolution of microstructures in nuclear fuels under high-burn-up conditions is critical for extending fuel refueling cycles and enhancing nuclear reactor safety.In this study,a phase-field model is proposed to examine the evolution of high-burn-up structures in polycrystalline UO_(2).The formation and growth of recrystallized grains were initially investigated.It was demonstrated that recrystallization kinetics adhere to the Kolmogorov–Johnson–Mehl–Avrami(KJMA)equation,and that recrystallization represents a process of free-energy reduction.Subsequently,the microstructural evolution in UO_(2) was analyzed as the burn up increased.Gas bubbles acted as additional nucleation sites,thereby augmenting the recrystallization kinetics,whereas the presence of recrystallized grains accelerated bubble growth by increasing the number of grain boundaries.The observed variations in the recrystallization kinetics and porosity with burn-up closely align with experimental findings.Furthermore,the influence of grain size on microstructure evolution was investigated.Larger grain sizes were found to decrease porosity and the occurrence of high-burn-up structures.
基金National Natural Science Foundation of China(No.52373281)National Energy-Saving and Low-Carbon Materials Production and Application Demonstration Platform Program,China(No.TC220H06N)。
文摘The research,fabrication and development of piezoelectric nanofibrous materials offer effective solutions to the challenges related to energy consumption and non-renewable resources.However,enhancing their electrical output still remains a significant challenge.Here,a strategy of inducing constrained phase separation on single nanofibers via shear force was proposed.Employing electrospinning technology,a polyacrylonitrile/polyvinylidene difluoride(PAN/PVDF)nanofibrous membrane was fabricated in one step,which enabled simultaneous piezoelectric and triboelectric conversion within a single-layer membrane.Each nanofiber contained independent components of PAN and PVDF and exhibited a rough surface.The abundant frictional contact points formed between these heterogeneous components contributed to an enhanced endogenous triboelectric output,showcasing an excellent synergistic effect of piezoelectric and triboelectric response in the nanofibrous membrane.Additionally,the component mass ratio influenced the microstructure,piezoelectric conformation and piezoelectric performance of the PAN/PVDF nanofibrous membranes.Through comprehensive performance comparison,the optimal mass ratio of PAN to PVDF was determined to be 9∶1.The piezoelectric devices made of the optimal PAN/PVDF nanofibrous membranes with rough nanofiber surfaces generated an output voltage of 20 V,which was about 1.8 times that of the smooth one at the same component mass ratio.The strategy of constrained phase separation on the surface of individual nanofibers provides a new approach to enhance the output performance of single-layer piezoelectric nanofibrous materials.
基金supported by the Beijing Natural Science Foundation (5252014)the National Natural Science Foundation of China (62303063)。
文摘Bird vocalizations are pivotal for ecological monitoring,providing insights into biodiversity and ecosystem health.Traditional recognition methods often neglect phase information,resulting in incomplete feature representation.In this paper,we introduce a novel approach to bird vocalization recognition(BVR)that integrates both amplitude and phase information,leading to enhanced species identification.We propose MHARes Net,a deep learning(DL)model that employs residual blocks and a multi-head attention mechanism to capture salient features from logarithmic power(POW),Instantaneous Frequency(IF),and Group Delay(GD)extracted from bird vocalizations.Experiments on three bird vocalization datasets demonstrate our method's superior performance,achieving accuracy rates of 94%,98.9%,and 87.1%respectively.These results indicate that our approach provides a more effective representation of bird vocalizations,outperforming existing methods.This integration of phase information in BVR is innovative and significantly advances the field of automatic bird monitoring technology,offering valuable tools for ecological research and conservation efforts.
基金Project supported financially by the National Natural Science Foundation of China (Grant No. 52372100)the National Key Research and Development Program of China (Grant No. 2019YFA0307900)。
文摘Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effective Hamiltonian method in conjuction with the phase-field model, we have successfully reproduced the thermal hysteresis observed in ferroelectric materials during phase transitions. The computational results regarding the electrocaloric effect from these two different computational scales closely align with experimental measurements. Furthermore, we analyze how the first-order ferroelectric phase transition gradually diminishes with an increasing applied electric field, exhibiting characteristics of second-order-like phase transition. By employing the characteristic parameters of thermal hysteresis, we have established a pathway for calculations across different computational scales, thereby providing theoretical support for further investigations into the properties of ferroelectric materials through concurrent multiscale simulations.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1532113,11475170,11905041)Anhui Provincial Natural Science Foundation(Grant No.2208085MA18)Fundamental Research Funds for the Central Universities(Grant No.JZ2022HGTB0244)。
文摘In x-ray dark-field imaging using dual phase grating interferometer,multi-contrast signals are extracted from a set of acquired phase-stepping data by using the least-squares fitting algorithm.The extracted mean intensity,amplitude and visibility signals may be intrinsically biased.However,it is still unclear how large these biases are and how the data acquisition parameters influence the biases in the extracted signals.This work set out to address these questions.Analytical expressions of the biases of the extracted signals were theoretically derived by using a second-order Taylor series expansion.Extensive numerical simulations were performed to validate the theoretical results.It is illustrated that while the estimated mean intensity signal is always unbiased,the estimated amplitude and visibility signals are both positively biased.While the biases of the estimated amplitude signals are proportional to the inverse of the total number of phase steps,the biases of the estimated visibility signals are inversely proportional to the product of the total number of phase steps and the mean number of photons counted per phase step.Meanwhile,it is demonstrated that the dependence of the biases on the mean visibility is quite different from that of Talbot-Lau interferometer due to the difference in the intensity model.We expect that these results can be useful for data acquisition optimizations and interpretation of x-ray dark-field images.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52472153,11704081,62488201)the National Key Research and Development Program of China(Grant No.2022YFA1204100)+2 种基金National Science and Technology Innovation Talent Cultivation Program(Grant No.2023BZRC016)Guangxi Natural Science Foundation(Grant No.2020GXNSFAA297182)the special fund for“Guangxi Bagui Scholars”。
文摘Two-dimensional(2D)moirésuperlattices with a small twist in orientation exhibit a broad range of physical properties due to the complicated intralayer and interlayer interactions modulated by the twist angle.Here,we report a metal-semiconductor phase transition in homojunction moirésuperlattices of NiS_2 and PtTe_2 with large twist angles based on high-throughput screening of 2D materials MX_(2)(M=Ni,Pd,Pt;X=S,Se,Te)via density functional theory(DFT)calculations.Firstly,the calculations for different stacking configurations(AA,AB and AC)reveal that AA stacking ones are stable for all the bilayer MX_(2).The metallic or semiconducting properties of these 2D materials remain invariable for different stacking without twisting except for NiS_2 and PtTe_2.For the twisted configurations,NiS_2 transfers from metal to semiconductor when the twist angles are 21.79°,27.79°,32.20°and 60°.PtTe_2 exhibits a similar transition at 60°.The phase transition is due to the weakened d-p orbital hybridization around the Fermi level as the interlayer distance increases in the twisted configurations.Further calculations of untwisted bilayers with increasing interlayer distance demonstrate that all the materials undergo metal-semiconductor phase transition with the increased interlayer distance because of the weakened d-p orbital hybridization.These findings provide fundamental insights into tuning the electronic properties of moirésuperlattices with large twist angles.
基金financially supported by the National Natural Science Foundation of China(No.51902025).
文摘Rapid advances in thermal management technology and the increasing need for multi-energy conversion have placed stringent energy efficiency requirements on next-generation shape-stable composite phase change materials(PCMs).Magnetically-responsive phase change thermal storage materials are considered an emerging concept for energy storage systems,enabling PCMs to perform unprecedented functions(such as green energy utilization,magnetic thermotherapy,drug release,etc.).The combination of multifunctional magnetic nanomaterials and PCMs is a milestone in the creation of advanced multifunctional composite PCMs.However,a timely and comprehensive review of composite PCMs based on magnetic nanoparticle modification is still missing.Herein,we furnish an exhaustive exposition elucidating the cutting-edge advancements in magnetically responsive composite PCMs.We delve deeply into the multifarious roles assumed by distinct nanoparticles within composite PCMs of varying dimensions,meticulously scrutinizing the intricate interplay between their architectures and thermophysical attributes.Moreover,we prognosticate future research trajectories,delineate alternative stratagems,and illuminate prospective avenues.This review is intended to stimulate broader academic interest in interdisciplinary fields and provide valuable insights into the development of next-generation magnetically-responsive composite PCMs.
基金Supported by the Special Foundation for Guangxi Ba Gui Scholars and Junwu Scholars of Guangxi Universitysupported by the National Natural Science Foundation of China(12275350)。
文摘In this study,we investigate the critical phenomena of Kerr-AdS black holes under the modified first law of thermodynamics.Specifically,we considered modified black hole thermodynamics that exhibit a van der Waalslike phase structure.All critical exponents were calculated,and then,a swallowtail diagram of free energy was plotted.Comparing with existing results,the main difference is the correspondence between the thermal quantities of Kerr-AdS black holes and the van der Waals system.In a previous study[Y.D.Tsai,X.N.Wu,and Y.Yang,Phys.Rev.D 85044005(2012)],the correspondence was(Ω_(H),J)→(V,P),while in our study,the correspondence was(J,Ω_(H))→(V,P).This difference was owing to the rotating effect.The modified black hole thermodynamics were associated with rotating observers.The free energy in such a reference contains extra rotating energy,which induces a Legendre transformation in the(Ω_(H),J)cross-section,causing the difference in correspondence.
基金National Natural Science Foundation of China(Nos.52301041,52022017,52065009,52371005)Special Fund for Special Posts of Guizhou University,China(No.[2023]26)+1 种基金Science and Technology Planning Project of Guizhou Province,China(No.ZK2021269)Fundamental Research Funds for the Central Universities,China(No.DUT23YG104)。
文摘Microstructural characterization,mass loss tests,hydrogen evolution tests,electrochemical measurements,and corrosion morphology observations were conducted to investigate the effect of the secondary phases on the corrosion behavior of the as-cast Mg−7Sn−1Zn−1Y(TZW711)alloy after solution treatment(T4)and aging treatment(T6).The results show that the T4-TZW711 alloy possesses the highest corrosion resistance in the early corrosion stage.This is because the dissolution of Mg2Sn reduces the cathodic current density and increases the charge transfer resistance(Rct).When the corrosion time is prolonged,the undissolved and clustered MgSnY phase will peel off from the T4-TZW711 alloy surface,thereby increasing the corrosion rate of the alloy.After aging treatment,the undissolved MgSnY phase is dispersed,which results in a lower localized corrosion sensitivity of T6-TZW711 alloy than that of the T4-TZW711 alloy,suggesting that the T6 treatment can enhance the corrosion resistance of Mg−7Sn−1Zn−1Y alloys.
基金supported by the National Natural Science Foundation of China(No.52377212 and 51877173)program of Beijing Huairou Laboratory(ZD2022006A)+2 种基金the Key R&D Project of Shaanxi Province(2023-YBGY-057)the State Key Laboratory of Electrical Insulation and Power Equipment(EIPE22314,EIPE22306)the Natural Science Basic Research Program of Shaanxi(No.2023-JC-QN-0483).
文摘Reversible solid oxide cells(RSOCs)are capable of converting various energy resources,between electricity and chemical fuels,with high efficiency and flexibility,making them suitable for grid balancing and renewable energy consumption.However,the practical application of RSOCs is still limited by the insufficient activity and stability of the electrodes in different operating modes.Herein,a highly efficient symmetrical electrode composed of La_(0.3)Sr_(0.6)Ti_(0.1)Co_(0.2)Fe_(0.7)O_(3-δ)(LSTCF)nanofibers and in situ exsolved Co_(3)Fe_(7) nanoparticles is developed for boosting the performance of RSOCs.The reversible phase transition,high activity and stability of the electrode have been confirmed by a combination of experimental(e.g.,transmission electron microscopy and X-ray absorption fine structure)and computational studies.Electrolyte-supported RSOCs with the symmetrical electrode demonstrate excellent catalytic activity and stability,achieving a high peak power density of 0.98 W cm^(-2)in the fuel cell mode using H_(2)as the fuel(or 0.53 W cm^(-2)using CH_(4)as the fuel)and a high current density of 1.09 A cm^(-2) at 1.4 V in the CO_(2)electrolysis mode(or 1.03 A cm^(-2)at 1.3 V for H_(2)O electrolysis)at 800℃while maintaining excellent durability for over 100 h.
基金National Natural Science Foundation of China (No. 52274403)。
文摘The mechanical,thermodynamic properties and electrical conductivities of L1_(2)-Al_(3)X(X=Zr,Sc,Er,Yb,Hf)structural phases in aluminum conductors were investigated through a first-principles study.The results demonstrate that all structural phases have good alloy-forming ability and structural stability,where Al_(3)Zr is the most superior.Al_(3)Zr,Al_(3)Hf and Al_(3)Sc have enhanced shear and deformation resistance in comparison to other phases.Within the temperature range of 200−600 K,Al_(3)Er and Al_(3)Yb possess the greatest thermodynamic stability,followed by Al_(3)Hf,Al_(3)Zr and Al_(3)Sc.Al_(3)Er and Al_(3)Yb have higher thermodynamic stability than Al_(3)Hf,Al_(3)Zr and Al_(3)Sc.All structural phases exhibit substantial metallic properties,indicating their good electrical conductivity.The electrical conductivities of Al_(3)Hf and Al_(3)Zr are higher than those of Al_(3)Er,Al_(3)Yb and Al_(3)Sc.The covalent bond properties in Al_(3)Sc,Al_(3)Er and Al_(3)Yb enhance the hardness,brittleness and thermodynamic stability of the structural phase.The thermodynamic stability of Al_(3)Sc is significantly reduced by ionic bonds.
