In the classical Newtonian mechanics, the gravity fields of static thin loop and double spheres are two simple but foundational problems. However, in the Einstein’s theory of gravity, they are not simple. In fact, we...In the classical Newtonian mechanics, the gravity fields of static thin loop and double spheres are two simple but foundational problems. However, in the Einstein’s theory of gravity, they are not simple. In fact, we do not know their solutions up to now. Based on the coordinate transformations of the Kerr and the Kerr-Newman solutions of the Einstein’s equation of gravity field with axial symmetry, the gravity fields of static thin loop and double spheres are obtained. The results indicate that, no matter how much the mass and density are, there are singularities at the central point of thin loop and the contact point of double spheres. What is more, the singularities are completely exposed in vacuum. Space near the surfaces of thin loop and spheres are highly curved, although the gravity fields are very weak. These results are inconsistent with practical experience and completely impossible. By reasonable analogy, black holes with singularity in cosmology and astrophysics are something illusive. Caused by the mathematical description of curved space-time, they do not exist in real world actually. If there are black holes in the universe, they can only be the types of the Newtonian black holes without singularities, rather than the Einstein’s singularity black holes. In order to escape the puzzle of singularity thoroughly, the description of gravity should return to the traditional form of dynamics in flat space. The renormalization of gravity and the unified description of four basic interactions may be possible only based on the frame of flat space-time. Otherwise, theses problems can not be solved forever. Physicists should have a clear understanding about this problem.展开更多
Recent various experiments have provided evidence supporting the emergence of loop-current order in kagome metals. Particularly superconductivity in AV_(3)Sb_(5) is significantly enhanced when this charge order is sup...Recent various experiments have provided evidence supporting the emergence of loop-current order in kagome metals. Particularly superconductivity in AV_(3)Sb_(5) is significantly enhanced when this charge order is suppressed by pressure or doping. Distinct from magnetic order, loop-current order does not couple directly to spin and thus whether such fluctuations can enhance superconductivity remains elusive. We design a sign problem-free bilayer kagome model coupled to quantum Ising spins through bond currents and perform determinant quantum Monte Carlo simulations to explore single-particle properties and superconductivity arising from 2 × 2 loopcurrent fluctuations. We find that this loop-current order induces intriguing band folding, band broadening,and gap opening around saddle points. Remarkably, our pairing susceptibility analysis identifies a dominant enhancement of superconductivity due to loop-current fluctuations, with the dominant pairing being the chiral d-wave channel. This pairing primarily occurs within the intra-sublattice channel and involves third nearestneighbor sites, attributed to the unique sublattice texture associated with van Hove singularities. We also discuss potential experimental implications for kagome superconductors.展开更多
Looped light in a recent sophisticated real three-slit experiment is interpreted as a strong justification of the old theoretical Peano-Hilbert spacetime model of Ord and El Naschie. This in turn entails the existence...Looped light in a recent sophisticated real three-slit experiment is interpreted as a strong justification of the old theoretical Peano-Hilbert spacetime model of Ord and El Naschie. This in turn entails the existence of extra fractal dimensions and consequently of real dark energy density in full agreement with previous analysis as well as accurate measurements and observations of COBE, WMAP, and the type 1a supernova.展开更多
This paper presents a compact ultra-low-power phase-locked loop (PLL) based binary phase-shift keying(BPSK)demodulator. The loop-filter-less(LPF-less) PLL is proposed to make phase of PLL output carrier signal track t...This paper presents a compact ultra-low-power phase-locked loop (PLL) based binary phase-shift keying(BPSK)demodulator. The loop-filter-less(LPF-less) PLL is proposed to make phase of PLL output carrier signal track the phase of BPSK signal in real time. Thus, the maximum date rate can be significantly extended to the half of the carrier frequency(f_(carrier)) with a very compact size compared to prior PLL-based BPSK demodulators. Furthermore, eliminating all the static power in our LPF-less PLL, the energy efficiency is obviously improved. Fabricated in a 40-nm CMOS process, our prototype occupies 0.0012-mm^(2)core active area, and achieves the maximum data rate of 6.78 Mb/s (f_(carrier)/2) at f_(carrier)of 13.56 MHz. The power consumption and energy efficiency is 4.47 μW and 0.66 pJ/bit at 6.78-Mb/s data rate, respectively.展开更多
As space technology advances,thermal control systems must effectively collect and dissipate heat from distributed,multi-source environments.Loop heat pipe is a highly reliable two-phase heat transfer component,but it ...As space technology advances,thermal control systems must effectively collect and dissipate heat from distributed,multi-source environments.Loop heat pipe is a highly reliable two-phase heat transfer component,but it has several limitations when addressing multi-source heat dissipation.Inspired by the transport and heat dissipation system of plants,large trees achieve stable and efficient liquid supply under the influence of two driving forces:capillary force during transpiration in the leaves(pull)and root pressure generated by osmotic pressure in the roots(push).The root pressure provides an effective liquid supply with a driving force exceeding 2 MPa,far greater than the driving force in conventional capillary-pumped two-phase loops.Research has shown that osmotic heat pipes offer a powerful driving force,and combining osmotic pressure with capillary force has significant advantages.Therefore,this paper designs a multi-evaporator,dual-drive two-phase loop,using both osmotic pressure and capillary force to solve the multi-source heat dissipation challenge.First,a transmembrane water flux model for the osmotic pressure-driven device was established to predict the maximum heat transfer capacity of the dual-drive two-phase loop.Then,an experimental setup for a multi-evaporator“osmotic pressure+capillary force”dual-drive two-phase loop was constructed,capable of transferring at least 235 W of power under a reverse gravity condition of 20 m.The study also analyzed the effects of reverse gravity height,heat load distribution among the three evaporators,startup sequence,and varying branch resistances on the performance of the dual-drive two-phase loop.展开更多
In-situ TEM observation was conducted during Ni^(+)&He^(+)dual-beam irradiation to monitor the evolution of dislocation loops accompanied by He bubbles in the Ni-based alloy GH3535.Two distinct evolutions of dislo...In-situ TEM observation was conducted during Ni^(+)&He^(+)dual-beam irradiation to monitor the evolution of dislocation loops accompanied by He bubbles in the Ni-based alloy GH3535.Two distinct evolutions of dislocation loops,driven by residual stresses,were observed within the monitored grains.Hence,molec-ular dynamics(MD)simulations were employed to reveal the effects of stress magnitude and direction on loop evolution,including size,number density,type and variation.The simulations revealed that the presence of compressive stress reduced the formation energy of perfect dislocation loops,thus promoting their formation.Stress state was found to influence the preferential orientation of the loops,and com-pressive stress resulted in a decreased number density of dislocation loops but an increase in their size.This establishes a clear relationship between stress state and magnitude and the evolution of dislocation loops during ion beam irradiation.Additionally,the nature and characteristics of dislocation loops were quantified to explore the effects of He concentrations on their evolution.The higher He concentration not only promotes the nucleation of dislocation loops,leading to their higher number density,but also facil-itates the unfaulting evolution by increasing the stacking fault energy(SFE).Moreover,the accumulation of He in the lower-He-concentration sample led to the growth of dislocation loops in multiple stages,explaining their nearly identical average sizes when compared to the higher-He-concentration sample.展开更多
The reaction characteristics of calcium-based materials during calcium looping(CaL)process are pivotal in the efficiency of CaL thermochemical energy storage(TCES)and CO_(2)capture systems.Currently,metal oxide doping...The reaction characteristics of calcium-based materials during calcium looping(CaL)process are pivotal in the efficiency of CaL thermochemical energy storage(TCES)and CO_(2)capture systems.Currently,metal oxide doping is the primary method to enhance the reaction characteristics of calcium-based materials over multiple cycles.In particular,co-doping with variable-valence metal oxides(VVMOs)can effectively increase the oxygen vacancy content in calcium-based materials,significantly improving their cyclic reaction characteristics.However,there are so numerous VVMOs co-doping schemes that the experimental screening process is complex,consuming considerable time and economic costs.Density functional theory(DFT)calculations have been widely used to reveal the impact of metal oxide doping on the cyclic reaction characteristics of calcium-based materials,with calculation results showing good agreement with experimental conclusions.Nevertheless,there is still a lack of research on utilizing DFT to screen calcium-based materials,and a systematic research methodology has not yet been established.In this study,a systematic DFT-based screening methodology for calcium-based materials was proposed.A series of key parameters for DFT calculations including CO_(2)adsorption energy,oxygen vacancy formation energy,and sintering resistance were proposed.Furthermore,a preliminary mathematical model to predict the CaL TCES and CO_(2)capture performance of calcium-based materials was introduced.The aforementioned DFT method was employed to screen for VVMOs co-doped calcium-based materials.The results revealed that Mn and Ce co-doped calcium-based materials exhibited superior DFT-predicted reaction characteristics.These DFT predictions were validated through experimental assessments of cyclic thermochemical energy storage,CO_(2)capture,and relevant characterization.The outcomes demonstrate a high degree of consistency among DFT-based predictions,experimental results,and characterization.Hence,the DFT-based screening methodology for calcium-based materials proposed herein is a viable solution,poised to offer theoretical insights for the efficient design of calcium-based materials.展开更多
The present work primarily aims to explore the neuronal calcium(Ca^(2+)),IP_(3),and dopamine(DA)signaling systems through a feedback loop model.To date,there has been no exploration of this feedback model in fractiona...The present work primarily aims to explore the neuronal calcium(Ca^(2+)),IP_(3),and dopamine(DA)signaling systems through a feedback loop model.To date,there has been no exploration of this feedback model in fractional-order dynamical systems.This feedback loop model incorporates several crucial mechanisms like the buffering process,IP_(3)-receptor,ryanodine receptor,plasma membrane Ca^(2+)ATPase and sarcoplasmic/endoplasmic reticulum calcium ATPase(SERCA)pump,leak,sodium-calcium exchanger,voltage-gated Ca^(2+)channel,Orai channels,DA-dependent IP_(3)synthesis,and others.By incorporating these mechanisms,the model aims to provide a more comprehensive and realistic understanding of the system under investigation.The present model incorporates fractional-order dynamics along both spatial and temporal dimensions to examine the impacts of superdiffusion and memory showing Brownian motion of Ca^(2+),IP_(3),and DA signaling molecules.The bidirectional feedback between calcium and IP_(3)signaling systems,unidirectional feedback between calcium and dopamine signaling systems,and unidirectional feedback between IP_(3)and dopamine signaling systems have been incorporated into the present model.These feedback loops establish interactions among calcium,IP_(3),and dopamine signaling systems within neuronal cells.The numerical findings were obtained by using the Crank-Nicholson method with the Grunwald technique for fractional space derivatives and the L1method for fractional time derivatives in conjunction with the Gauss-Seidel Iterations.This research specifically investigates the implications of cell memory as well as superdiffusion on Ca^(2+),IP_(3),and DA dynamics in neuronal cells,which are interactive nonlinear systems.The superdiffusion process results in a reduction in Ca^(2+),IP_(3),and DA concentrations,while cellular memory leads to an increase in ion and molecule concentrations in neuronal cells during the initial time.The disruption of any given process can lead to imbalances in calcium,IP_(3),and DA systems,hence contributing to neurotoxicity and cellular demise.展开更多
Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, the...Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, there are some problems in the conventional method, such as the error of amplitude, the shift of phase angle and the non-determinacy of initial oriented angle. In this paper, two one-order low-pass filters are adopted instead of the pure integrator in the virtual line-flux-linkage observer, which can steady the phase and amplitude. Furthermore, an original scheme of harmonics detection under the rotating coordinate is advanced based on the simplified space vector pulse width modulation (SVPWM) strategy. Meanwhile, by using the new SVPWM algorithm, the voltage space vector diagram of the three-level inverter can be simplified and applied into that of two-level inverter, and this makes the control for Neutral Point potential easier.展开更多
This paper studies the method for measuring the loop resistance of GIS conductor pole based on the super capacitor producing impulse current up to several thousand amperes. This method overcomes the limitations of con...This paper studies the method for measuring the loop resistance of GIS conductor pole based on the super capacitor producing impulse current up to several thousand amperes. This method overcomes the limitations of conventional diagnostic method. Typical GIS conductor poles are chosen. Based on FEA and lab tests, the effect of different forms of current and contact condition, relationship between the temperature of contact and the loop resistance is researched. In full- scale testing under realistic operating conditions on the new 220 kV GIS using prototype instrumentation a very good sensitivity in an early stage was obtained.展开更多
Owing to wide applications of automatic control systems in the process industries, the impacts of controller performance on industrial processes are becoming increasingly significant. Consequently, controller maintena...Owing to wide applications of automatic control systems in the process industries, the impacts of controller performance on industrial processes are becoming increasingly significant. Consequently, controller maintenance is critical to guarantee routine operations of industrial processes. The workflow of controller maintenance generally involves the following steps: monitor operating controller performance and detect performance degradation, diagnose probable root causes of control system malfunctions, and take specific actions to resolve associated problems. In this article, a comprehensive overview of the mainstream of control loop monitoring and diagnosis is provided, and some existing problems are also analyzed and discussed. From the viewpoint of synthesizing abundant information in the context of big data, some prospective ideas and promising methods are outlined to potentially solve problems in industrial applications.展开更多
BACKGROUND In the treatment of rectal cancer,a temporary loop ileostomy(TLI)is created after low anterior resection to protect bowel function in the postoperative period.Dehydration and kidney failure are significant ...BACKGROUND In the treatment of rectal cancer,a temporary loop ileostomy(TLI)is created after low anterior resection to protect bowel function in the postoperative period.Dehydration and kidney failure are significant potential complications in loop ileostomies.Compared to late closure(3-6 months),early closure(10-14 days)of the TLI may facilitate faster patient recovery and shorter hospital stays.AIM To compare early and late closure of TLIs and demonstrate that early stoma closure can be performed without increasing morbidity.METHODS This study included patients who underwent TLI for rectal cancer,with data collected prospectively between June 2016 and October 2024 and analyzed retrospectively.Patients whose stomas were closed in the late period(3-6 months)between June 2016 and October 2022(group A)were compared with those who underwent early closure(10-14 days)between October 2022 and 2024(group B),with the primary outcome being complication rate and the secondary outcome being quality of life.RESULTS A total of 270 TLIs were created(70.9%).Of these,120(44.4%)were closed in the late period(group A),and 150(55.6%)were closed in the early period(group B).There was no statistically significant difference between group A and group B in terms of demographic and clinicopathological characteristics(P>0.05).Perioperative(anesthesia management,operative time,blood loss,surgical technique)and postoperative findings(anastomotic leak,infection)were similar between the two groups and were not statistically significant(P>0.05).There were no statistically significant differences in complication rates as the primary outcome between the two groups.Quality of life as a secondary outcome was significantly higher in the early closure group(P<0.05).CONCLUSION No statistically significant difference was found between early and late loop ileostomy closure in terms of perioperative and postoperative morbidity.Early closure accelerated patients’psychological and social recovery.展开更多
In-loop filters have been comprehensively explored during the development of video coding standards due to their remarkable noise-reduction capabilities.In the early stage of video coding,in-loop filters,such as the d...In-loop filters have been comprehensively explored during the development of video coding standards due to their remarkable noise-reduction capabilities.In the early stage of video coding,in-loop filters,such as the deblocking filter,sample adaptive offset,and adaptive loop filter,were performed separately for each component.Recently,cross-component filters have been studied to improve chroma fidelity by exploiting correlations between the luma and chroma channels.This paper introduces the cross-component filters used in the state-ofthe-art video coding standards,including the cross-component adaptive loop filter and cross-component sample adaptive offset.Crosscomponent filters aim to reduce compression artifacts based on the correlation between different components and provide more accurate pixel reconstruction values.We present their origin,development,and status in the current video coding standards.Finally,we conduct discussions on the further evolution of cross-component filters.展开更多
The microstructure and mechanical properties of 2524 Al alloy after quenching in liquid nitrogen(LN_(2))were investigated by TEM and compared with those of cold water quenching.The results show that the LN_(2) quenchi...The microstructure and mechanical properties of 2524 Al alloy after quenching in liquid nitrogen(LN_(2))were investigated by TEM and compared with those of cold water quenching.The results show that the LN_(2) quenching process effectively induces the formation of dislocation loops.These loops become large and unevenly distribute after aging for 15 min.Furthermore,such loops become rapidly immobilized by the precipitation of coarse S phases after 1 h aging.The alloy quenched in LN_(2) demonstrates superior peak hardness and displays a more rapid response to subsequent aging treatments compared with the cold water-quenched one.Despite the short aging time,LN_(2)-quenched sample achieves tensile strength of 488 MPa.This enhanced strength is attributed to the strengthening effect of numerous finely dispersed Guinier-Preston-Bagaryatsky(GPB)zones,in conjunction with the inhomogeneous formation of S phase on the dislocation loops.展开更多
Hydrogen energy,as the ultimate clean energy,effectively avoids the greenhouse effect.Chemical looping hydrogen production(CLHP),a versatile energy conversion and production technology,has garnered extensive attention...Hydrogen energy,as the ultimate clean energy,effectively avoids the greenhouse effect.Chemical looping hydrogen production(CLHP),a versatile energy conversion and production technology,has garnered extensive attention.CLHP demands redox catalysts with high oxygen capacity,regulatable reactivity,and structural integrity even under harsh operational conditions.Currently,sintering,agglomeration,and inactivation of redox catalysts during cyclic lattice oxygen release and restoration are challenging,hindering the wide industrialization of the chemical looping(CL)process.Moreover,the precise control of activity and reaction rate of the redox catalysts to flexibly accommodate the demands of various reaction substrates remains unclear.This paper introduces the design of a nano-scaled redox catalyst featuring a unique core-shell structure.By precisely controlling the shell thickness,a series of hierarchical Fe_(2)O_(3)@SiO_(2)redox catalysts were successfully synthesized.Building on this achievement,an in-depth investigation was conducted into the impact of the thickness and spatial structure of the inert support on the stability and mass transfer rate of the redox catalyst,aiming to achieve a perfect balance between these two factors during the CLHP process.A thin shell(70 nm)exhibits excellent cyclic stability,maintaining consistent performance in 30 consecutive redox cycles,while a thicker shell(200 nm)undergoes rapid deactivation due to the formation of a substantial amount of iron silicate.In-situ transmission electron microscopy(TEM)reveals that the SiO_(2)shell effectively restricts the agglomeration of Fe_(2)O_(3).The unique core-shell structure and controllable shell thickness offer novel insights into the flexible design of efficient and durable hierarchical redox catalysts with spatial structure.展开更多
Rack-level loop thermosyphons have been widely adopted as a solution to data centers’growing energy demands.While numerous studies have highlighted the heat transfer performance and energy-saving benefits of this sys...Rack-level loop thermosyphons have been widely adopted as a solution to data centers’growing energy demands.While numerous studies have highlighted the heat transfer performance and energy-saving benefits of this system,its economic feasibility,water usage effectiveness(WUE),and carbon usage effectiveness(CUE)remain underexplored.This study introduces a comprehensive evaluation index designed to assess the applicability of the rack-level loop thermosyphon system across various computing hub nodes.The air wet bulb temperature Ta,w was identified as the most significant factor influencing the variability in the combination of PUE,CUE,and WUE values.The results indicate that the rack-level loop thermosyphon system achieves the highest score in Lanzhou(94.485)and the lowest in Beijing(89.261)based on the comprehensive evaluation index.The overall ranking of cities according to the comprehensive evaluation score is as follows:Gansu hub(Lanzhou)>Inner Mongolia hub(Hohhot)>Ningxia hub(Yinchuan)>Yangtze River Delta hub(Shanghai)>Chengdu Chongqing hub(Chongqing)>Guangdong-Hong Kong-Macao Greater Bay Area hub(Guangzhou)>Guizhou hub(Guiyang)>Beijing-Tianjin-Hebei hub(Beijing).Furthermore,Hohhot,Lanzhou,and Yinchuan consistently rank among the top three cities for comprehensive scores across all load rates,while Guiyang(at a 25%load rate),Guangzhou(at a 50%load rate),and Beijing(at 75%and 100%load rates)exhibited the lowest comprehensive scores.展开更多
Background:U2AF homology motif kinase 1(UHMK1)has been associated with RNA processing and protein phosphorylation,thereby influencing tumor progression.The study aimed to explore its regulatory mechanisms and biologic...Background:U2AF homology motif kinase 1(UHMK1)has been associated with RNA processing and protein phosphorylation,thereby influencing tumor progression.The study aimed to explore its regulatory mechanisms and biological functions in human prostate cancer(PCa).Methods:In this study,we systematically evaluated the expression and prognostic significance of UHMK1 in public databases,followed by validation through immunohis-tochemistry(IHC)in PCa specimens.Both gain-of-function and loss-of-function experiments were conducted to elucidate the role of UHMK1 in vitro and in vivo.Additionally,a series of molecular and biochemical assays were performed to investigate the regulatory mechanisms underlying UHMK1 activity.Results:Our findings revealed that UHMK1 expression was significantly upregulated in PCa tissues and correlated with poor patient prognosis,as demonstrated by analysis of public datasets and confirmed by immunohistochemical staining.Functional studies showed that UHMK1 depletion suppressed tumor cell proliferation and metastasis,while its overexpression promoted these processes.Mechanistically,we identified that UHMK1 phosphorylates nuclear receptor coactivator 3(NCOA3),which subsequently activates activating transcription factor 4(ATF4)to upregulate methylenetetrahydrofolate dehy-drogenase 2(MTHFD2)transcription.Interestingly,MTHFD2 was found to reciprocally enhance UHMK1 expression,establishing a positive feedback loop.Conclusions:In conclusion,our data suggest that the UHMK1-MTHFD2 axis forms a positive feedback loop that drives PCa progression.Targeting this loop represents a promising therapeutic strategy for restraining prostate cancer development and progression.展开更多
文摘In the classical Newtonian mechanics, the gravity fields of static thin loop and double spheres are two simple but foundational problems. However, in the Einstein’s theory of gravity, they are not simple. In fact, we do not know their solutions up to now. Based on the coordinate transformations of the Kerr and the Kerr-Newman solutions of the Einstein’s equation of gravity field with axial symmetry, the gravity fields of static thin loop and double spheres are obtained. The results indicate that, no matter how much the mass and density are, there are singularities at the central point of thin loop and the contact point of double spheres. What is more, the singularities are completely exposed in vacuum. Space near the surfaces of thin loop and spheres are highly curved, although the gravity fields are very weak. These results are inconsistent with practical experience and completely impossible. By reasonable analogy, black holes with singularity in cosmology and astrophysics are something illusive. Caused by the mathematical description of curved space-time, they do not exist in real world actually. If there are black holes in the universe, they can only be the types of the Newtonian black holes without singularities, rather than the Einstein’s singularity black holes. In order to escape the puzzle of singularity thoroughly, the description of gravity should return to the traditional form of dynamics in flat space. The renormalization of gravity and the unified description of four basic interactions may be possible only based on the frame of flat space-time. Otherwise, theses problems can not be solved forever. Physicists should have a clear understanding about this problem.
基金supported by the National Natural Science Foundation of China (Grant No. 12447103)financial support from the MERIT-WINGS course provided by the University of Tokyo+10 种基金the Fellowship for Integrated Materials Science and Career Development provided by the Japan Science and Technology Agencysupport from the computational resource of Wisteria/BDEC-01 provided by Information Technology Center, the University of Tokyo, for the Monte Carlo simulationthe support by the National Natural Science Foundation of China (Grant No. 12404275)the Fundamental Research Program of Shanxi Province (Grant No. 202403021212015)support from the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter-ct.qmat (EXC 2147, Project No. 390858490)supported by the National Natural Science Foundation of China (Grant No. 12274289)the National Key R&D Program of China (Grant Nos. 2022YFA1402702 and 2021YFA1401400)the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0301902)Yangyang Development Fund, and Startup Funds from SJTUsupported by the National Key R&D Program of China (Grant No. 2023YFA1407300)the National Natural Science Foundation of China (Grant No. 12047503)。
文摘Recent various experiments have provided evidence supporting the emergence of loop-current order in kagome metals. Particularly superconductivity in AV_(3)Sb_(5) is significantly enhanced when this charge order is suppressed by pressure or doping. Distinct from magnetic order, loop-current order does not couple directly to spin and thus whether such fluctuations can enhance superconductivity remains elusive. We design a sign problem-free bilayer kagome model coupled to quantum Ising spins through bond currents and perform determinant quantum Monte Carlo simulations to explore single-particle properties and superconductivity arising from 2 × 2 loopcurrent fluctuations. We find that this loop-current order induces intriguing band folding, band broadening,and gap opening around saddle points. Remarkably, our pairing susceptibility analysis identifies a dominant enhancement of superconductivity due to loop-current fluctuations, with the dominant pairing being the chiral d-wave channel. This pairing primarily occurs within the intra-sublattice channel and involves third nearestneighbor sites, attributed to the unique sublattice texture associated with van Hove singularities. We also discuss potential experimental implications for kagome superconductors.
文摘Looped light in a recent sophisticated real three-slit experiment is interpreted as a strong justification of the old theoretical Peano-Hilbert spacetime model of Ord and El Naschie. This in turn entails the existence of extra fractal dimensions and consequently of real dark energy density in full agreement with previous analysis as well as accurate measurements and observations of COBE, WMAP, and the type 1a supernova.
基金supported by the National Natural Science Foundation of China under grant 62222409 and 62174153by Key Research Program of Frontier Sciences, CAS, under grant ZDBS-LY-JSC008。
文摘This paper presents a compact ultra-low-power phase-locked loop (PLL) based binary phase-shift keying(BPSK)demodulator. The loop-filter-less(LPF-less) PLL is proposed to make phase of PLL output carrier signal track the phase of BPSK signal in real time. Thus, the maximum date rate can be significantly extended to the half of the carrier frequency(f_(carrier)) with a very compact size compared to prior PLL-based BPSK demodulators. Furthermore, eliminating all the static power in our LPF-less PLL, the energy efficiency is obviously improved. Fabricated in a 40-nm CMOS process, our prototype occupies 0.0012-mm^(2)core active area, and achieves the maximum data rate of 6.78 Mb/s (f_(carrier)/2) at f_(carrier)of 13.56 MHz. The power consumption and energy efficiency is 4.47 μW and 0.66 pJ/bit at 6.78-Mb/s data rate, respectively.
基金Science Foundation for Distinguished Young Scholars 2020-JCJQ-ZQ-042 Intelligent and Bionic Spacecraft Thermal Control Technology Inspired by Tree Sap Transport Principle.
文摘As space technology advances,thermal control systems must effectively collect and dissipate heat from distributed,multi-source environments.Loop heat pipe is a highly reliable two-phase heat transfer component,but it has several limitations when addressing multi-source heat dissipation.Inspired by the transport and heat dissipation system of plants,large trees achieve stable and efficient liquid supply under the influence of two driving forces:capillary force during transpiration in the leaves(pull)and root pressure generated by osmotic pressure in the roots(push).The root pressure provides an effective liquid supply with a driving force exceeding 2 MPa,far greater than the driving force in conventional capillary-pumped two-phase loops.Research has shown that osmotic heat pipes offer a powerful driving force,and combining osmotic pressure with capillary force has significant advantages.Therefore,this paper designs a multi-evaporator,dual-drive two-phase loop,using both osmotic pressure and capillary force to solve the multi-source heat dissipation challenge.First,a transmembrane water flux model for the osmotic pressure-driven device was established to predict the maximum heat transfer capacity of the dual-drive two-phase loop.Then,an experimental setup for a multi-evaporator“osmotic pressure+capillary force”dual-drive two-phase loop was constructed,capable of transferring at least 235 W of power under a reverse gravity condition of 20 m.The study also analyzed the effects of reverse gravity height,heat load distribution among the three evaporators,startup sequence,and varying branch resistances on the performance of the dual-drive two-phase loop.
基金supported by the National Natural Science Foundation of China(Nos.U2341261 and 12375280)the Young Potential Program of Shanghai Institute of Applied Physics,Chinese Academy of Sciences(No.YXJH-2022002)the National MCF Energy R&D Program(No.2022YFE03110000).
文摘In-situ TEM observation was conducted during Ni^(+)&He^(+)dual-beam irradiation to monitor the evolution of dislocation loops accompanied by He bubbles in the Ni-based alloy GH3535.Two distinct evolutions of dislocation loops,driven by residual stresses,were observed within the monitored grains.Hence,molec-ular dynamics(MD)simulations were employed to reveal the effects of stress magnitude and direction on loop evolution,including size,number density,type and variation.The simulations revealed that the presence of compressive stress reduced the formation energy of perfect dislocation loops,thus promoting their formation.Stress state was found to influence the preferential orientation of the loops,and com-pressive stress resulted in a decreased number density of dislocation loops but an increase in their size.This establishes a clear relationship between stress state and magnitude and the evolution of dislocation loops during ion beam irradiation.Additionally,the nature and characteristics of dislocation loops were quantified to explore the effects of He concentrations on their evolution.The higher He concentration not only promotes the nucleation of dislocation loops,leading to their higher number density,but also facil-itates the unfaulting evolution by increasing the stacking fault energy(SFE).Moreover,the accumulation of He in the lower-He-concentration sample led to the growth of dislocation loops in multiple stages,explaining their nearly identical average sizes when compared to the higher-He-concentration sample.
基金supported by the National Natural Science Foundation of China(52276204 and U22A20435)。
文摘The reaction characteristics of calcium-based materials during calcium looping(CaL)process are pivotal in the efficiency of CaL thermochemical energy storage(TCES)and CO_(2)capture systems.Currently,metal oxide doping is the primary method to enhance the reaction characteristics of calcium-based materials over multiple cycles.In particular,co-doping with variable-valence metal oxides(VVMOs)can effectively increase the oxygen vacancy content in calcium-based materials,significantly improving their cyclic reaction characteristics.However,there are so numerous VVMOs co-doping schemes that the experimental screening process is complex,consuming considerable time and economic costs.Density functional theory(DFT)calculations have been widely used to reveal the impact of metal oxide doping on the cyclic reaction characteristics of calcium-based materials,with calculation results showing good agreement with experimental conclusions.Nevertheless,there is still a lack of research on utilizing DFT to screen calcium-based materials,and a systematic research methodology has not yet been established.In this study,a systematic DFT-based screening methodology for calcium-based materials was proposed.A series of key parameters for DFT calculations including CO_(2)adsorption energy,oxygen vacancy formation energy,and sintering resistance were proposed.Furthermore,a preliminary mathematical model to predict the CaL TCES and CO_(2)capture performance of calcium-based materials was introduced.The aforementioned DFT method was employed to screen for VVMOs co-doped calcium-based materials.The results revealed that Mn and Ce co-doped calcium-based materials exhibited superior DFT-predicted reaction characteristics.These DFT predictions were validated through experimental assessments of cyclic thermochemical energy storage,CO_(2)capture,and relevant characterization.The outcomes demonstrate a high degree of consistency among DFT-based predictions,experimental results,and characterization.Hence,the DFT-based screening methodology for calcium-based materials proposed herein is a viable solution,poised to offer theoretical insights for the efficient design of calcium-based materials.
文摘The present work primarily aims to explore the neuronal calcium(Ca^(2+)),IP_(3),and dopamine(DA)signaling systems through a feedback loop model.To date,there has been no exploration of this feedback model in fractional-order dynamical systems.This feedback loop model incorporates several crucial mechanisms like the buffering process,IP_(3)-receptor,ryanodine receptor,plasma membrane Ca^(2+)ATPase and sarcoplasmic/endoplasmic reticulum calcium ATPase(SERCA)pump,leak,sodium-calcium exchanger,voltage-gated Ca^(2+)channel,Orai channels,DA-dependent IP_(3)synthesis,and others.By incorporating these mechanisms,the model aims to provide a more comprehensive and realistic understanding of the system under investigation.The present model incorporates fractional-order dynamics along both spatial and temporal dimensions to examine the impacts of superdiffusion and memory showing Brownian motion of Ca^(2+),IP_(3),and DA signaling molecules.The bidirectional feedback between calcium and IP_(3)signaling systems,unidirectional feedback between calcium and dopamine signaling systems,and unidirectional feedback between IP_(3)and dopamine signaling systems have been incorporated into the present model.These feedback loops establish interactions among calcium,IP_(3),and dopamine signaling systems within neuronal cells.The numerical findings were obtained by using the Crank-Nicholson method with the Grunwald technique for fractional space derivatives and the L1method for fractional time derivatives in conjunction with the Gauss-Seidel Iterations.This research specifically investigates the implications of cell memory as well as superdiffusion on Ca^(2+),IP_(3),and DA dynamics in neuronal cells,which are interactive nonlinear systems.The superdiffusion process results in a reduction in Ca^(2+),IP_(3),and DA concentrations,while cellular memory leads to an increase in ion and molecule concentrations in neuronal cells during the initial time.The disruption of any given process can lead to imbalances in calcium,IP_(3),and DA systems,hence contributing to neurotoxicity and cellular demise.
文摘Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, there are some problems in the conventional method, such as the error of amplitude, the shift of phase angle and the non-determinacy of initial oriented angle. In this paper, two one-order low-pass filters are adopted instead of the pure integrator in the virtual line-flux-linkage observer, which can steady the phase and amplitude. Furthermore, an original scheme of harmonics detection under the rotating coordinate is advanced based on the simplified space vector pulse width modulation (SVPWM) strategy. Meanwhile, by using the new SVPWM algorithm, the voltage space vector diagram of the three-level inverter can be simplified and applied into that of two-level inverter, and this makes the control for Neutral Point potential easier.
文摘This paper studies the method for measuring the loop resistance of GIS conductor pole based on the super capacitor producing impulse current up to several thousand amperes. This method overcomes the limitations of conventional diagnostic method. Typical GIS conductor poles are chosen. Based on FEA and lab tests, the effect of different forms of current and contact condition, relationship between the temperature of contact and the loop resistance is researched. In full- scale testing under realistic operating conditions on the new 220 kV GIS using prototype instrumentation a very good sensitivity in an early stage was obtained.
基金Supported by the National Basic Research Program of China(2012CB720505)the National Natural Science Foundation of China(21276137,61433001)+1 种基金Tsinghua University Initiative Scientific Research Programthe seventh framework programme(FP7-PEOPLE-2013-IRSES-612230)of European Union
文摘Owing to wide applications of automatic control systems in the process industries, the impacts of controller performance on industrial processes are becoming increasingly significant. Consequently, controller maintenance is critical to guarantee routine operations of industrial processes. The workflow of controller maintenance generally involves the following steps: monitor operating controller performance and detect performance degradation, diagnose probable root causes of control system malfunctions, and take specific actions to resolve associated problems. In this article, a comprehensive overview of the mainstream of control loop monitoring and diagnosis is provided, and some existing problems are also analyzed and discussed. From the viewpoint of synthesizing abundant information in the context of big data, some prospective ideas and promising methods are outlined to potentially solve problems in industrial applications.
文摘BACKGROUND In the treatment of rectal cancer,a temporary loop ileostomy(TLI)is created after low anterior resection to protect bowel function in the postoperative period.Dehydration and kidney failure are significant potential complications in loop ileostomies.Compared to late closure(3-6 months),early closure(10-14 days)of the TLI may facilitate faster patient recovery and shorter hospital stays.AIM To compare early and late closure of TLIs and demonstrate that early stoma closure can be performed without increasing morbidity.METHODS This study included patients who underwent TLI for rectal cancer,with data collected prospectively between June 2016 and October 2024 and analyzed retrospectively.Patients whose stomas were closed in the late period(3-6 months)between June 2016 and October 2022(group A)were compared with those who underwent early closure(10-14 days)between October 2022 and 2024(group B),with the primary outcome being complication rate and the secondary outcome being quality of life.RESULTS A total of 270 TLIs were created(70.9%).Of these,120(44.4%)were closed in the late period(group A),and 150(55.6%)were closed in the early period(group B).There was no statistically significant difference between group A and group B in terms of demographic and clinicopathological characteristics(P>0.05).Perioperative(anesthesia management,operative time,blood loss,surgical technique)and postoperative findings(anastomotic leak,infection)were similar between the two groups and were not statistically significant(P>0.05).There were no statistically significant differences in complication rates as the primary outcome between the two groups.Quality of life as a secondary outcome was significantly higher in the early closure group(P<0.05).CONCLUSION No statistically significant difference was found between early and late loop ileostomy closure in terms of perioperative and postoperative morbidity.Early closure accelerated patients’psychological and social recovery.
基金supported in part by National Science Foundation of China under Grant No.62031013PCL-CMCC Foundation for Science and Innovation under Grant No.2024ZY1C0040+1 种基金New Cornerstone Science Foundation for the Xplorer PrizeHigh performance Computing Platform of Peking University。
文摘In-loop filters have been comprehensively explored during the development of video coding standards due to their remarkable noise-reduction capabilities.In the early stage of video coding,in-loop filters,such as the deblocking filter,sample adaptive offset,and adaptive loop filter,were performed separately for each component.Recently,cross-component filters have been studied to improve chroma fidelity by exploiting correlations between the luma and chroma channels.This paper introduces the cross-component filters used in the state-ofthe-art video coding standards,including the cross-component adaptive loop filter and cross-component sample adaptive offset.Crosscomponent filters aim to reduce compression artifacts based on the correlation between different components and provide more accurate pixel reconstruction values.We present their origin,development,and status in the current video coding standards.Finally,we conduct discussions on the further evolution of cross-component filters.
基金supported by the National Natural Science Foundation of China(No.52001106)the Natural Science Foundation of Hebei Province,China(No.E2022202158).
文摘The microstructure and mechanical properties of 2524 Al alloy after quenching in liquid nitrogen(LN_(2))were investigated by TEM and compared with those of cold water quenching.The results show that the LN_(2) quenching process effectively induces the formation of dislocation loops.These loops become large and unevenly distribute after aging for 15 min.Furthermore,such loops become rapidly immobilized by the precipitation of coarse S phases after 1 h aging.The alloy quenched in LN_(2) demonstrates superior peak hardness and displays a more rapid response to subsequent aging treatments compared with the cold water-quenched one.Despite the short aging time,LN_(2)-quenched sample achieves tensile strength of 488 MPa.This enhanced strength is attributed to the strengthening effect of numerous finely dispersed Guinier-Preston-Bagaryatsky(GPB)zones,in conjunction with the inhomogeneous formation of S phase on the dislocation loops.
基金financial support from the National Natural Science Foundation of China(52076209,22179027,22469006)the Foundation and Applied Foundation Research of Guangdong Province(2022B1515020045)the Heilongjiang Key Research and Development Project of China(JD22A026)。
文摘Hydrogen energy,as the ultimate clean energy,effectively avoids the greenhouse effect.Chemical looping hydrogen production(CLHP),a versatile energy conversion and production technology,has garnered extensive attention.CLHP demands redox catalysts with high oxygen capacity,regulatable reactivity,and structural integrity even under harsh operational conditions.Currently,sintering,agglomeration,and inactivation of redox catalysts during cyclic lattice oxygen release and restoration are challenging,hindering the wide industrialization of the chemical looping(CL)process.Moreover,the precise control of activity and reaction rate of the redox catalysts to flexibly accommodate the demands of various reaction substrates remains unclear.This paper introduces the design of a nano-scaled redox catalyst featuring a unique core-shell structure.By precisely controlling the shell thickness,a series of hierarchical Fe_(2)O_(3)@SiO_(2)redox catalysts were successfully synthesized.Building on this achievement,an in-depth investigation was conducted into the impact of the thickness and spatial structure of the inert support on the stability and mass transfer rate of the redox catalyst,aiming to achieve a perfect balance between these two factors during the CLHP process.A thin shell(70 nm)exhibits excellent cyclic stability,maintaining consistent performance in 30 consecutive redox cycles,while a thicker shell(200 nm)undergoes rapid deactivation due to the formation of a substantial amount of iron silicate.In-situ transmission electron microscopy(TEM)reveals that the SiO_(2)shell effectively restricts the agglomeration of Fe_(2)O_(3).The unique core-shell structure and controllable shell thickness offer novel insights into the flexible design of efficient and durable hierarchical redox catalysts with spatial structure.
基金supported by the Natural Science Foundation of Hunan Province,China(Grant Nos.2023JJ50178 and 2023JJ50194)the Excellent Youth Project of Hunan Provincial Department of Education(Grant No.23B0542).
文摘Rack-level loop thermosyphons have been widely adopted as a solution to data centers’growing energy demands.While numerous studies have highlighted the heat transfer performance and energy-saving benefits of this system,its economic feasibility,water usage effectiveness(WUE),and carbon usage effectiveness(CUE)remain underexplored.This study introduces a comprehensive evaluation index designed to assess the applicability of the rack-level loop thermosyphon system across various computing hub nodes.The air wet bulb temperature Ta,w was identified as the most significant factor influencing the variability in the combination of PUE,CUE,and WUE values.The results indicate that the rack-level loop thermosyphon system achieves the highest score in Lanzhou(94.485)and the lowest in Beijing(89.261)based on the comprehensive evaluation index.The overall ranking of cities according to the comprehensive evaluation score is as follows:Gansu hub(Lanzhou)>Inner Mongolia hub(Hohhot)>Ningxia hub(Yinchuan)>Yangtze River Delta hub(Shanghai)>Chengdu Chongqing hub(Chongqing)>Guangdong-Hong Kong-Macao Greater Bay Area hub(Guangzhou)>Guizhou hub(Guiyang)>Beijing-Tianjin-Hebei hub(Beijing).Furthermore,Hohhot,Lanzhou,and Yinchuan consistently rank among the top three cities for comprehensive scores across all load rates,while Guiyang(at a 25%load rate),Guangzhou(at a 50%load rate),and Beijing(at 75%and 100%load rates)exhibited the lowest comprehensive scores.
基金supported by the National Natural Science Foundation of China(Grant Nos.81902617 and 82100816)Guangdong Natural Science Foundation(Grant No.2021A1515012322)Guangzhou Basic and Applied Basic Research Subject-Young Doctor’s“Sailing”Project(Grant No.2024A04J4702).
文摘Background:U2AF homology motif kinase 1(UHMK1)has been associated with RNA processing and protein phosphorylation,thereby influencing tumor progression.The study aimed to explore its regulatory mechanisms and biological functions in human prostate cancer(PCa).Methods:In this study,we systematically evaluated the expression and prognostic significance of UHMK1 in public databases,followed by validation through immunohis-tochemistry(IHC)in PCa specimens.Both gain-of-function and loss-of-function experiments were conducted to elucidate the role of UHMK1 in vitro and in vivo.Additionally,a series of molecular and biochemical assays were performed to investigate the regulatory mechanisms underlying UHMK1 activity.Results:Our findings revealed that UHMK1 expression was significantly upregulated in PCa tissues and correlated with poor patient prognosis,as demonstrated by analysis of public datasets and confirmed by immunohistochemical staining.Functional studies showed that UHMK1 depletion suppressed tumor cell proliferation and metastasis,while its overexpression promoted these processes.Mechanistically,we identified that UHMK1 phosphorylates nuclear receptor coactivator 3(NCOA3),which subsequently activates activating transcription factor 4(ATF4)to upregulate methylenetetrahydrofolate dehy-drogenase 2(MTHFD2)transcription.Interestingly,MTHFD2 was found to reciprocally enhance UHMK1 expression,establishing a positive feedback loop.Conclusions:In conclusion,our data suggest that the UHMK1-MTHFD2 axis forms a positive feedback loop that drives PCa progression.Targeting this loop represents a promising therapeutic strategy for restraining prostate cancer development and progression.
