A new scheme is offered for minimizing carrier Rayleigh backscattering(CRB) in single feeder fiber based wavelength division multiplexed passive optical network(WDM-PON). The proposed scheme is based on single side ba...A new scheme is offered for minimizing carrier Rayleigh backscattering(CRB) in single feeder fiber based wavelength division multiplexed passive optical network(WDM-PON). The proposed scheme is based on single side band carrier suppressed(SSBCS) signal, both at network and receiver sides, used for the first time at optical line terminal(OLT) and optical network unit(ONU) sides. We use dual-drive Mach-zehnder modulator(DD-MZM) for generating SSB-CS signals, which decreases the expense per bit in full transmission. SSB-CS mitigates CRB, both at OLT and ONU sides, because of having no chance of reflections from the carrier. Since no extra dedicated RF or laser source is used at ONU side, we thus achieve cost effective colorless WDM-PON system. Suppressed signals from four channels, each of 10 Gbps, are multiplexed before injecting into the fiber span of 25 km at OLT. At ONU side, half of the downlink power is used for re-modulating the data signal. The simulation results show an errorfree transmission. Moreover, the detailed power budget calculations show that the proposed scheme can be sought out for splitting ratio up to 128. Hence it offers enough system's margin for unseen losses.展开更多
With the rapid development of wireless systems,the demand for frequency resources has been increasing in recent years.Therefore,it is necessary to consider the high-quality communication method that efficiently utiliz...With the rapid development of wireless systems,the demand for frequency resources has been increasing in recent years.Therefore,it is necessary to consider the high-quality communication method that efficiently utilizes finite frequency resources.In this paper,Single Sideband 16 Pulse Amplitude Modulation(SSB 16PAM)scheme for the uplink communication is proposed.It transmits data in only Lower Sideband(LSB)without extra Hilbert components.Under Additive White Gaussian Noise(AWGN)channel environment,Bit Error Rate(BER)performance of the proposed scheme is superior by 3 dB in terms of Carrier-to-Noise Ratio(CNR)to 256 Quadrature Amplitude Modulation(256QAM)scheme with the same frequency efficiency and the same Peak-to-Average Power Ratio(PAPR).Our proposed scheme employs the original frequency domain filter on the transmitter side to form an ideal spectrum.The configuration of its process is almost similar to Single Carrier-Frequency Division Multiple Access(SC-FDMA),moreover,half of the input data on the frequency domain is removed.The proposed frequency domain filter produces the SSB-modulated spectrum with a roll-off rate of zero without degrading the BER performance.展开更多
In recent years,train-tail swaying of 160 km/h electric multiple units(EMUs)inside single-line tunnels has been heavily researched,because the issue needs to be solved urgently.In this paper,a co-simulation model of v...In recent years,train-tail swaying of 160 km/h electric multiple units(EMUs)inside single-line tunnels has been heavily researched,because the issue needs to be solved urgently.In this paper,a co-simulation model of vortex-induced vibration(VIV)of the tail car body is established,and the aerodynamics of train-tail swaying is studied.The simulation results were confirmed through a field test of operating EMUs.Furthermore,the influence mechanism of train-tail swaying on the wake flow field is studied in detail through a wind-tunnel experiment and a simulation of a reduced-scaled train model.The results demonstrate that the aerodynamic force frequency(i.e.,vortex-induced frequency)of the train tail increases linearly with train speed.When the train runs at 130 km/h,with a small amplitude of train-tail swaying(within 10 mm),the vortex-induced frequency is 1.7 Hz,which primarily depends on the nose shape of the train tail.After the tail car body nose is extended,the vortex-induced frequency is decreased.As the swaying amplitude of the train tail increases(exceeding 25 mm),the separation point of the high-intensity vortex in the train wake shifts downstream to the nose tip,and the vortex-induced frequency shifts from 1.7 Hz to the nearby car body hunting(i.e.,the primary hunting)frequency of 1.3 Hz,which leads to the frequency-locking phenomenon of VIV,and the resonance intensifies train-tail swaying.For the motor vehicle of the train tail,optimization of the yaw damper to improve its primary hunting stability can effectively alleviate train-tail swaying inside single-line tunnels.Optimization of the tail car body nose shape reduces the amplitude of the vortex-induced force,thereby weakening the aerodynamic effect and solving the problem of train-tail swaying inside the single-line tunnels.展开更多
In this paper,we present a circuit model of single-quantum-well InGaN/GaN light-emitting diodes based on the standard rate equations.Two rate equations describe carrier transport processes occurring in sep-arate confi...In this paper,we present a circuit model of single-quantum-well InGaN/GaN light-emitting diodes based on the standard rate equations.Two rate equations describe carrier transport processes occurring in sep-arate confinement heterostructure and quantum well respectively,and the third equation describes the varied photons in quantum well.By using the presented model,impacts of quantum well thickness on the static and dynamic performances are investigated.Simulated results show that LED with 4 nm well exhibits better lightcurrent(L-I)performance,but LED with 3 nm well presents wider 3 dB modulation bandwidth.It reveals that high carrier density in quantum well is detrimental to the static performance,but beneficial to the dynamic performance.展开更多
Unlike mammals,zebrafish possess a remarkable ability to regenerate their spinal cord after injury,making them an ideal vertebrate model for studying regeneration.While previous research has identified key cell types ...Unlike mammals,zebrafish possess a remarkable ability to regenerate their spinal cord after injury,making them an ideal vertebrate model for studying regeneration.While previous research has identified key cell types involved in this process,the underlying molecular and cellular mechanisms remain largely unexplored.In this study,we used single-cell RNA sequencing to profile distinct cell populations at different stages of spinal cord injury in zebrafish.Our analysis revealed that multiple subpopulations of neurons showed persistent activation of genes associated with axonal regeneration post injury,while molecular signals promoting growth cone collapse were inhibited.Radial glial cells exhibited significant proliferation and differentiation potential post injury,indicating their intrinsic roles in promoting neurogenesis and axonal regeneration,respectively.Additionally,we found that inflammatory factors rapidly decreased in the early stages following spinal cord injury,creating a microenvironment permissive for tissue repair and regeneration.Furthermore,oligodendrocytes lost maturity markers while exhibiting increased proliferation following injury.These findings demonstrated that the rapid and orderly regulation of inflammation,as well as the efficient proliferation and redifferentiation of new neurons and glial cells,enabled zebrafish to reconstruct the spinal cord.This research provides new insights into the cellular transitions and molecular programs that drive spinal cord regeneration,offering promising avenues for future research and therapeutic strategies.展开更多
Pediatric cancers are particularly significant due to their uncommon occurrence in children,driven by a variety of underlying factors.Because of their distinct molecular and genetic makeup,which makes early detection ...Pediatric cancers are particularly significant due to their uncommon occurrence in children,driven by a variety of underlying factors.Because of their distinct molecular and genetic makeup,which makes early detection challenging,they are linked to problems.Diagnostic methods like imaging and tissue biopsy are only effective when the tumor has reached a size that can be identified.The liquid biopsy technique,the least intrusive and most convenient diagnostic method,is the subject of this review.It focuses on the significance of single cell analysis in examining uncommon cancer types.The many biomarkers found in bodily fluids and the cancer types they are linked to in children have been assessed,as has the potential route towards early detection and cancer recurrence forecasting.Combining the single cell liquid biopsy with the newest technologies,such as computational and multi-omics approaches,which have improved the efficiency of processing massive and unique genetic data,appears promising.This article discusses on a number of case reports for uncommon pediatric malignancies,such as Neuroblastoma,Medulloblastoma,Wilms Tumor,Rhabdomyosarcoma,Ewing Sarcoma,and Retinoblastoma,as well as their liquid biopsy profiles.Furthermore,the findings raise ethical questions regarding the therapeutic application of the technology as well as possible difficulties related to clinical translation.The likelihood that this single cell liquid biopsy will be clinically validated and eventually used as a routine diagnostic tool for uncommon pediatric cancers will rise with the realistic approach to sensitivity monitoring,specificity upgrading,and optimization.展开更多
Fenton-like technology based on peroxymonosulfate activation has shown great potential in refractory organics degradation.In this work,single Fe atom catalysts were synthesized through facile ball milling and exhibite...Fenton-like technology based on peroxymonosulfate activation has shown great potential in refractory organics degradation.In this work,single Fe atom catalysts were synthesized through facile ball milling and exhibited very high performance in peroxymonosulfate activation.The Fe single-atom filled an N vacancy on the triazine ring edge of C_(3)N_(4),as confirmed through X-ray absorption fine structure,density functional calculation and elec-tron paramagnetic resonance.The SAFe_(0.4)–C_(3)N_(4)/PMS system could completely remove phenol(20 mg/L)within 10 min and its first-order kinetic constant was 12.3 times that of the Fe_(3)O_(4)/PMS system.Under different ini-tial pH levels and in various anionic environments,SAFe_(0.4)–C_(3)N_(4) still demonstrated excellent catalytic activity,achieving a removal rate of over 90%for phenol within 12 min.In addition,SAFe_(0.4)–C_(3)N_(4) exhibited outstanding selectivity in reaction systems with different pollutants,showing excellent degradation effects on electron-rich pollutants only.Hydroxyl radicals(•OH),singlet oxygen(1O_(2))and high-valent iron oxide(Fe(Ⅳ)=O)were de-tected in the SAFe_(0.4)–C_(3)N_(4)/PMS system through free radical capture experiments.Further experiments on the quenching of active species and a methyl phenyl sulfoxide probe confirmed that 1O_(2) and Fe(Ⅳ)=O played dom-inant roles.Additionally,the change in the current response after adding PMS and phenol in succession proved that a direct electron transfer path between organic matter and the catalyst surface was unlikely to exist in the SAFe_(0.4)–C_(3)N_(4)/PMS/Phenol degradation system.This study provides a new demonstration of the catalytic mech-anism of single-atom catalysts.展开更多
Mitochondria are the central organelles that allow eukaryotic cells to efficiently convert nutrients into energy for cellular functions such as anabolic reactions,movement,and regulation.A reduction in the number of m...Mitochondria are the central organelles that allow eukaryotic cells to efficiently convert nutrients into energy for cellular functions such as anabolic reactions,movement,and regulation.A reduction in the number of mitochondria or the occurrence of dysfunctional mitochondria leads to serious diseases such as the Leigh syndrome.However,such changes have also been connected to Alzheimer’s disease(AD)and many more diseases of different organ systems and occur during the aging process.Mitochondria are,therefore.展开更多
Sliver defects are a group of low-to-medium angle misoriented grains in Ni-based single crystal superalloys that have received more attention in recent years.Occurrence of these defects can negatively affect the mecha...Sliver defects are a group of low-to-medium angle misoriented grains in Ni-based single crystal superalloys that have received more attention in recent years.Occurrence of these defects can negatively affect the mechanical properties of single crystal components.Therefore,studying the mechanisms of sliver formation and its effects on the final properties of alloys is of great importance.In this article,recent studies on the sliver defects were reviewed.Accordingly,the mechanisms of sliver formation as well as factors contributing to sliver initiation were studied.Additionally,effects of slivers on the mechanical properties of single crystal superalloys were discussed.Dendrite deformation and dendrite fracture are the main mechanisms for the sliver formation.This is a consequence of local stress concentration on dendrites during solidification.Therefore,locations such as inclusions,pores,geometrically complex areas,mould walls,freckle channels,etc.can be considered as the potential factors that promote the sliver initiation.Sliver formation significantly degrades the creep life of single-crystal superalloys.Studies have shown that when crystallographic misorientation exceeds approximately15°,creep life can be reduced by up to 47%.Despite the absence of a standardized criterion for predicting or preventing sliver initiation and propagation,their occurrence can be minimized through optimization of solidification parameters,careful grain selection,proper casting geometry design,and rigorous control of material purity and equipment conditions.展开更多
High-performance lead-free piezoelectric single crystals are urgently needed for next-generation actuators and transducers.In this study,we reveal that a compositionally driven tetragonal-pseudocubic(T-PC)phase bounda...High-performance lead-free piezoelectric single crystals are urgently needed for next-generation actuators and transducers.In this study,we reveal that a compositionally driven tetragonal-pseudocubic(T-PC)phase boundary,in conjunction with an octahedral order-disorder tilting transition,significantly enhances the piezoelectric response in Nb^(5+)-substitution(Bi_(0.48)Na_(0.425)K_(0.055)Ba_(0.04))(Ti_(0.98)Nb_(0.02))O_(3)(BNKBT-2Nb)single crystals.The crystal achieves an outstanding piezoelectric coefficient of d33=662 pC/N at room temperature.In situ X-ray diffraction confirms an electric field-induced transition from the PC to T phase.Atomic-resolution HADDF-STEM analysis reveals an increase in the c/a ratio(c/a>1.01)on the local scale and ordered octahe-dral tilting of the a^(0)a^(0)c+type driven by the poling field.The single crystals exhibit excellent piezoelectric per-formance over a broad temperature range,achieving a peak d_(33) of 920 pC/N at approximately 92℃.Furthermore,the polar states exhibit a pronounced frequency dependence near the depolarization temperature.These findings provide critical insight into the structure-property relationship and offer a promising pathway for designing advanced lead-free piezoelectric crystals for functional electromechanical applications.展开更多
Turbine blades,due to their intricate geometry,are exposed to multiaxial stresses during operation.Consequently,it is imperative to examine the anisotropy of their stress-rupture behavior across various testing scenar...Turbine blades,due to their intricate geometry,are exposed to multiaxial stresses during operation.Consequently,it is imperative to examine the anisotropy of their stress-rupture behavior across various testing scenarios,particularly under high-temperature conditions.Stress-rupture behavior of a Ni-based single crystal superalloy was investigated under a load varying from 100 MPa to 137 MPa at 1,100℃ for both[001]-and[111]-orientated specimens.Results demonstrate that the rupture behavior of[111]-orientated specimens exhibits obviously higher sensitive to applied stress compared to[001]-orientated specimens.This difference is primarily attributed to the orientation dependentγ'coarsening behavior and distinct dislocation interactions atγ/γ'interfaces.In[001]-oriented specimens,plate-likeγ/γ'rafts rapidly form alongside well-developed interfacial dislocation networks,where theγ/γ'misfit stress dominates the microstructural evolution.In contrast,the[111]-orientated specimens exhibit retained,coarsenedγ'precipitates embedded within theγmatrix,accompanied by poorly developed interfacial dislocation networks.展开更多
High-performance fiber fabrics and composites experienced transverse compression deformation at ultrahigh strain rates near the impact point when subjected to high-velocity impacts,which significantly affected their b...High-performance fiber fabrics and composites experienced transverse compression deformation at ultrahigh strain rates near the impact point when subjected to high-velocity impacts,which significantly affected their ballistic limits.In this paper,a fiber-scale experimental method for characterizing ultrahigh strain-rate transverse compression behavior was proposed.To begin with,in order to measure the extremely low stress and strain in small specimens,the conventional Hopkinson bar was reduced to the hundred-micron scale,thereby achieving wave impedance matching with single fibers.In addition,tangential and normal laser Doppler velocimetry(LDV)methods were employed to realize non-contact,high-precision,and high-speed axial velocity measurements of micron-scale incident and transmission bars,respectively.Meanwhile,a microscopic observation system was used to facilitate the installation of miniature fiber samples.The experimental setup and procedures were introduced,and the system accuracy was verified through sample-free loading tests based on one-dimensional stress wave propagation theory.Dynamic compression experiments on Graphene-UHMWPE fibers were carried out,followed by post-compression microstructural characterization via scanning electron microscopy(SEM).Results demonstrated that successful mechanical characterization was achieved at strain rates exceeding 105,an order of magnitude higher than the previously reported maximum rates.Furthermore,during the loading process,the fibers underwent uniform compression deformation while exhibiting pronounced strain-rate effects.This method offers a novel approach for dynamic mechanical characterization of microscale single fibers,enabling the development of comprehensive strain-ratedependent material models to guide the design of advanced composites and high-performance fibers.展开更多
Overview of diabetic gastroparesis Diabetic gastroparesis(DGP)is a common gastrointestinal complication of diabetes mellitus,characterized primarily by delayed gastric emptying.With the rising prevalence of diabetes,t...Overview of diabetic gastroparesis Diabetic gastroparesis(DGP)is a common gastrointestinal complication of diabetes mellitus,characterized primarily by delayed gastric emptying.With the rising prevalence of diabetes,the incidence of DGP has increased annually,currently affecting approximately 50%of diabetic patients[1].Its main clinical manifestations include belching,nausea,vomiting,abdominal distension,and anorexia,which not only severely impair patients’quality of life but also trigger serious complications such as blood glucose fluctuations[2].Diagnosis primarily relies on clinical symptoms,exclusionary testing,and gastric emptying scintigraphy.展开更多
The increase in human population has led to imminent pressures to develop new edible proteins with decreased environmental footprints.The most promising approach involves the production of single cell protein(SCP)from...The increase in human population has led to imminent pressures to develop new edible proteins with decreased environmental footprints.The most promising approach involves the production of single cell protein(SCP)from yeasts,which have been utilized in a wide variety of foods for thousands of years.In this study,102 yeast strains isolated from traditional fermented pork(Nanx Wudl)were investigated for their potential as SCP producer for the first time.Based on preliminary screening,Saccharomyces cerevisiae Y70 and Candida parapsilosis H5Y13,both showing high protein content and excellent growth capability,were selected for further analysis via 4D-DIA proteomics technology.Proteomic analysis indicated that the oxidative metabolism pathways,including TCA cycle,oxidative phosphorylation and pentose phosphate pathway,may have a significant impact on global protein synthesis and production.This study provides useful information for selecting SCP-producing yeast from Chinese fermented meat products and contribute to a deeper understanding of the underlying metabolic mechanisms behind global protein synthesis in yeast.Furthermore,these findings also provide potential molecular targets for genetic engineering modifications in yeast,aimed at constructing highly efficient cell factories for protein production.展开更多
Exploring the influence of the coordination environment of single-atom catalysts(SACs)on the electrochemical CO_(2)reduction reaction is vital for assessing the reaction mechanism and structure-performance relationshi...Exploring the influence of the coordination environment of single-atom catalysts(SACs)on the electrochemical CO_(2)reduction reaction is vital for assessing the reaction mechanism and structure-performance relationship.However,it is challenging to engineer the coordination configuration of isolated active metal atoms precisely.Herein,we strategically manipulate the coordination number of the Co-N_(x) configuration by simply changing the order of adding the metal precursor toward improved CO_(2)electrolysis performance.Compared with the symmetric Co-N_(4)coordination,the asymmetric Co-N_(3)coordination leads to reinforced Co-N interaction and downshifted 3d orbital energy toward the Fermi level of the active Co sites,promoting the activation of CO_(2)molecules and the formation of critical intermediate^(*)COOH.The as-designed Co-N_(3)SAC displays excellent Faradaic efficiency(FE)of 98.4%for CO_(2)-to-CO conversion at a low potential of-0.80 V,together with decent FE over a wide potential range(-0.50 V to-1.10 V)and high durability.This study presents an ideal platform to manipulate the coordination number of atomically dispersed metal catalysts and provides a fundamental understanding of coordination configurationperformance correlation for CO_(2)electroreduction.展开更多
Alzheimer’s disease(AD)is the most common form of dementia.In addition to the lack of effective treatments,there are limitations in diagnostic capabilities.The complexity of AD itself,together with a variety of other...Alzheimer’s disease(AD)is the most common form of dementia.In addition to the lack of effective treatments,there are limitations in diagnostic capabilities.The complexity of AD itself,together with a variety of other diseases often observed in a patient’s history in addition to their AD diagnosis,make deciphering the molecular mechanisms that underlie AD,even more important.Large datasets of single-cell RNA sequencing,single-nucleus RNA-sequencing(snRNA-seq),and spatial transcriptomics(ST)have become essential in guiding and supporting new investigations into the cellular and regional susceptibility of AD.However,with unique technology,software,and larger databases emerging;a lack of integration of these data can contribute to ineffective use of valuable knowledge.Importantly,there was no specialized database that concentrates on ST in AD that offers comprehensive differential analyses under various conditions,such as sex-specific,region-specific,and comparisons between AD and control groups until the new Single-cell and Spatial RNA-seq databasE for Alzheimer’s Disease(ssREAD)database(Wang et al.,2024)was introduced to meet the scientific community’s growing demand for comprehensive,integrated,and accessible data analysis.展开更多
The rate capability and cycling stability of sodium metal batteries taking FeS_(2) or sulfur as cathode are limited due to their low reaction kinetics and severe shuttle effect.Herein,we rationally design a novel sing...The rate capability and cycling stability of sodium metal batteries taking FeS_(2) or sulfur as cathode are limited due to their low reaction kinetics and severe shuttle effect.Herein,we rationally design a novel single-atom-dispersed S_(2)-FeNC/FeS_(2) nanocluster heterojunction embedded in carbon spheres(SFNC/FeS_(2)) for the electrode material of sodium metal batteries.Interestingly,during the discharging process,the Na^(+) is inserted into FeS_(2) to generate Na_(2)S,as well as the unique electrochemical reaction between S_(2)-FeNC and Na^(+) to form Na_(2)S.Meanwhile,the FeNC can adsorb Na_(2)S and catalyze the conversion from Na_(2)S and Fe to FeS_(2) or from Na_(2)S and FeNC to S_(2)-FeNC for suppressing the shuttle effect and promoting the distinct hybrid reversible electrochemical behavior,which improves performance tremendously.Notably,the SFNC/FeS_(2) electrode delivers a specific capacity of 338.7 mAh g^(-1) after superlong 2000 cycles at a current density of 5.0 A g^(-1) and achieves a high energy density of 430.1 Wh Kg^(-1) at a current density of 0.05 A g^(-1).This work presents a novel approach to studying sodium metal batteries with hybrid behavior for excellent high energy density and cycling stability.展开更多
Dear Editor,This letter studies the problem of stealthy attacks targeting stochastic event-based estimation,alongside proposing measures for their mitigation.A general attack framework is introduced,and the correspond...Dear Editor,This letter studies the problem of stealthy attacks targeting stochastic event-based estimation,alongside proposing measures for their mitigation.A general attack framework is introduced,and the corresponding stealthiness condition is analyzed.To enhance system security,we advocate for a single-dimensional encryption method,showing that securing a singular data element is sufficient to shield the system from the perils of stealthy attacks.展开更多
Bismuth vanadate(BiVO_(4))is regarded as a promising photoanode for photoelectrochemical(PEC)water splitting.Despite its advantage in band gap and visible-light response,the BiVO_(4)exhibits an unsatisfactory achievin...Bismuth vanadate(BiVO_(4))is regarded as a promising photoanode for photoelectrochemical(PEC)water splitting.Despite its advantage in band gap and visible-light response,the BiVO_(4)exhibits an unsatisfactory achieving water splitting due to severe charge recombination.Herein,we elucidate an innovative approach involving the incorporation of single Ru atom with a CoFe-LDH cocatalyst(Ru_(0.51)-CoFe-LDH)and integrating it onto the BiVO_(4)semiconductor substrate.The resulting Ru_(0.51)-CoFe-LDH/BiVO_(4)photoanode film demonstrates commendable charge injection efficiency(76%)and charge collection efficiency(100%).Interestingly,the yield of hydrogen and oxygen increases linearly at a stoichiometric ratio of about 2:1,reaching 158.6 and 67.4μmol after140 min of irradiation,respectively.According to experimental characterization and density functional theory calculation,this remarkable performance results from single Ru atoms triggering the electron rearrangement of Ru_(0.51)-CoFe-LDH to engineer active sites and optimize interfacial energetics.Additionally,the negative shift of Ru_(0.51)-CoFe-LDH band edge gives rise to more conspicuous band bending of the n-n junction formed with BiVO_(4),expediting the separation and transfer of photogenerated electron-hole pairs at the interface.This work furnishes a new preparation perspective for PEC water splitting systems to construct single atoms in the semiconductor substrate.展开更多
Iron-based single-atom(SA)catalysts offer a promising alternative to noble-metal catalysts for the oxygen reduction reaction(ORR),yet their limited intrinsic activity and durability hinder practical energy device appl...Iron-based single-atom(SA)catalysts offer a promising alternative to noble-metal catalysts for the oxygen reduction reaction(ORR),yet their limited intrinsic activity and durability hinder practical energy device applications.Herein,we introduce a novel TiN/TiC-supported Fe SA catalyst(TiNC/Fe-NC)with a hierarchical heterostructure that synergistically enhances Fe-N_(x) site activity and accessibility.The TiNC/Fe-NC catalyst achieves outstanding ORR performances,with half-wave potentials(E_(1/2))of 0.852 V in acidic media and 0.942 V in alkaline media.Theoretical simulations reveal that strong electronic interaction and efficient charge transfer between TiNC and Fe-N_(x) sites optimize the adsorption energetics of key ORR intermediates,driving the enhanced activity.Remarkably,TiNC effectively scavenges reactive oxygen radicals generated at the Fe centers,ensuring exceptional durability with a minimal 28 mV loss in E_(1/2) after 10,000 cycles at 80℃in acid media.In practical applications,TiNC/Fe-NC delivers peak power densities of 306 mW cm^(-2) in zinc-air battery and 732 mW cm^(-2) in proton exchange membrane fuel cells,with remarkable long-term stability.This work establishes TiNC/Fe-NC as a highperformance,durable catalyst for advanced energy storage and conversion technologies.展开更多
基金financial supports from National High Technology 863 Program of China(No. 2013AA013403,2013AA013301/02,20 15AA015501/02)National NSFC(No. 61425022/61307086/ 61475024/6127515 8/61201151/61275074/61205066)+4 种基金NITC (No.2012DFG12110)Beijing Nova Program(No.Z141101001814048)Beijing Excellent Ph.D.Thesis Guidance Foundation (No.20121001302) are gratefully acknowledgedsupported by the Universities Ph.D.Special Research Funds (No.20120005110003/ 20120005120007)Fund of State Key Laboratory of IPOC (BUPT)
文摘A new scheme is offered for minimizing carrier Rayleigh backscattering(CRB) in single feeder fiber based wavelength division multiplexed passive optical network(WDM-PON). The proposed scheme is based on single side band carrier suppressed(SSBCS) signal, both at network and receiver sides, used for the first time at optical line terminal(OLT) and optical network unit(ONU) sides. We use dual-drive Mach-zehnder modulator(DD-MZM) for generating SSB-CS signals, which decreases the expense per bit in full transmission. SSB-CS mitigates CRB, both at OLT and ONU sides, because of having no chance of reflections from the carrier. Since no extra dedicated RF or laser source is used at ONU side, we thus achieve cost effective colorless WDM-PON system. Suppressed signals from four channels, each of 10 Gbps, are multiplexed before injecting into the fiber span of 25 km at OLT. At ONU side, half of the downlink power is used for re-modulating the data signal. The simulation results show an errorfree transmission. Moreover, the detailed power budget calculations show that the proposed scheme can be sought out for splitting ratio up to 128. Hence it offers enough system's margin for unseen losses.
文摘With the rapid development of wireless systems,the demand for frequency resources has been increasing in recent years.Therefore,it is necessary to consider the high-quality communication method that efficiently utilizes finite frequency resources.In this paper,Single Sideband 16 Pulse Amplitude Modulation(SSB 16PAM)scheme for the uplink communication is proposed.It transmits data in only Lower Sideband(LSB)without extra Hilbert components.Under Additive White Gaussian Noise(AWGN)channel environment,Bit Error Rate(BER)performance of the proposed scheme is superior by 3 dB in terms of Carrier-to-Noise Ratio(CNR)to 256 Quadrature Amplitude Modulation(256QAM)scheme with the same frequency efficiency and the same Peak-to-Average Power Ratio(PAPR).Our proposed scheme employs the original frequency domain filter on the transmitter side to form an ideal spectrum.The configuration of its process is almost similar to Single Carrier-Frequency Division Multiple Access(SC-FDMA),moreover,half of the input data on the frequency domain is removed.The proposed frequency domain filter produces the SSB-modulated spectrum with a roll-off rate of zero without degrading the BER performance.
基金supported by the National Natural Science Foundation of China(Nos.52372403 and U2268211)the Natural Science Foundation of Sichuan Province(No.2022NSFSC0034),China+1 种基金the National Railway Group Science and Technology Program(No.2023J071)the Traction Power State Key Laboratory of the Independent Research and Development Projects(No.2022TPL-T02),China.
文摘In recent years,train-tail swaying of 160 km/h electric multiple units(EMUs)inside single-line tunnels has been heavily researched,because the issue needs to be solved urgently.In this paper,a co-simulation model of vortex-induced vibration(VIV)of the tail car body is established,and the aerodynamics of train-tail swaying is studied.The simulation results were confirmed through a field test of operating EMUs.Furthermore,the influence mechanism of train-tail swaying on the wake flow field is studied in detail through a wind-tunnel experiment and a simulation of a reduced-scaled train model.The results demonstrate that the aerodynamic force frequency(i.e.,vortex-induced frequency)of the train tail increases linearly with train speed.When the train runs at 130 km/h,with a small amplitude of train-tail swaying(within 10 mm),the vortex-induced frequency is 1.7 Hz,which primarily depends on the nose shape of the train tail.After the tail car body nose is extended,the vortex-induced frequency is decreased.As the swaying amplitude of the train tail increases(exceeding 25 mm),the separation point of the high-intensity vortex in the train wake shifts downstream to the nose tip,and the vortex-induced frequency shifts from 1.7 Hz to the nearby car body hunting(i.e.,the primary hunting)frequency of 1.3 Hz,which leads to the frequency-locking phenomenon of VIV,and the resonance intensifies train-tail swaying.For the motor vehicle of the train tail,optimization of the yaw damper to improve its primary hunting stability can effectively alleviate train-tail swaying inside single-line tunnels.Optimization of the tail car body nose shape reduces the amplitude of the vortex-induced force,thereby weakening the aerodynamic effect and solving the problem of train-tail swaying inside the single-line tunnels.
文摘In this paper,we present a circuit model of single-quantum-well InGaN/GaN light-emitting diodes based on the standard rate equations.Two rate equations describe carrier transport processes occurring in sep-arate confinement heterostructure and quantum well respectively,and the third equation describes the varied photons in quantum well.By using the presented model,impacts of quantum well thickness on the static and dynamic performances are investigated.Simulated results show that LED with 4 nm well exhibits better lightcurrent(L-I)performance,but LED with 3 nm well presents wider 3 dB modulation bandwidth.It reveals that high carrier density in quantum well is detrimental to the static performance,but beneficial to the dynamic performance.
基金supported by the Jiangsu Province Traditional Chinese Medicine Technology Development Plan Project,Nos.MS2023113(to JC),MS2022090Young and Middle-aged Academic Leaders of Jiangsu Qing-Lan Project(to GL).
文摘Unlike mammals,zebrafish possess a remarkable ability to regenerate their spinal cord after injury,making them an ideal vertebrate model for studying regeneration.While previous research has identified key cell types involved in this process,the underlying molecular and cellular mechanisms remain largely unexplored.In this study,we used single-cell RNA sequencing to profile distinct cell populations at different stages of spinal cord injury in zebrafish.Our analysis revealed that multiple subpopulations of neurons showed persistent activation of genes associated with axonal regeneration post injury,while molecular signals promoting growth cone collapse were inhibited.Radial glial cells exhibited significant proliferation and differentiation potential post injury,indicating their intrinsic roles in promoting neurogenesis and axonal regeneration,respectively.Additionally,we found that inflammatory factors rapidly decreased in the early stages following spinal cord injury,creating a microenvironment permissive for tissue repair and regeneration.Furthermore,oligodendrocytes lost maturity markers while exhibiting increased proliferation following injury.These findings demonstrated that the rapid and orderly regulation of inflammation,as well as the efficient proliferation and redifferentiation of new neurons and glial cells,enabled zebrafish to reconstruct the spinal cord.This research provides new insights into the cellular transitions and molecular programs that drive spinal cord regeneration,offering promising avenues for future research and therapeutic strategies.
文摘Pediatric cancers are particularly significant due to their uncommon occurrence in children,driven by a variety of underlying factors.Because of their distinct molecular and genetic makeup,which makes early detection challenging,they are linked to problems.Diagnostic methods like imaging and tissue biopsy are only effective when the tumor has reached a size that can be identified.The liquid biopsy technique,the least intrusive and most convenient diagnostic method,is the subject of this review.It focuses on the significance of single cell analysis in examining uncommon cancer types.The many biomarkers found in bodily fluids and the cancer types they are linked to in children have been assessed,as has the potential route towards early detection and cancer recurrence forecasting.Combining the single cell liquid biopsy with the newest technologies,such as computational and multi-omics approaches,which have improved the efficiency of processing massive and unique genetic data,appears promising.This article discusses on a number of case reports for uncommon pediatric malignancies,such as Neuroblastoma,Medulloblastoma,Wilms Tumor,Rhabdomyosarcoma,Ewing Sarcoma,and Retinoblastoma,as well as their liquid biopsy profiles.Furthermore,the findings raise ethical questions regarding the therapeutic application of the technology as well as possible difficulties related to clinical translation.The likelihood that this single cell liquid biopsy will be clinically validated and eventually used as a routine diagnostic tool for uncommon pediatric cancers will rise with the realistic approach to sensitivity monitoring,specificity upgrading,and optimization.
基金supported by the National Natural Science Foundation of China(Nos.22406081,22276086,22306086)the Natural Science Foundation of Jiangxi Province(No.20232BAB213029),all of which are greatly acknowledged by the authors.
文摘Fenton-like technology based on peroxymonosulfate activation has shown great potential in refractory organics degradation.In this work,single Fe atom catalysts were synthesized through facile ball milling and exhibited very high performance in peroxymonosulfate activation.The Fe single-atom filled an N vacancy on the triazine ring edge of C_(3)N_(4),as confirmed through X-ray absorption fine structure,density functional calculation and elec-tron paramagnetic resonance.The SAFe_(0.4)–C_(3)N_(4)/PMS system could completely remove phenol(20 mg/L)within 10 min and its first-order kinetic constant was 12.3 times that of the Fe_(3)O_(4)/PMS system.Under different ini-tial pH levels and in various anionic environments,SAFe_(0.4)–C_(3)N_(4) still demonstrated excellent catalytic activity,achieving a removal rate of over 90%for phenol within 12 min.In addition,SAFe_(0.4)–C_(3)N_(4) exhibited outstanding selectivity in reaction systems with different pollutants,showing excellent degradation effects on electron-rich pollutants only.Hydroxyl radicals(•OH),singlet oxygen(1O_(2))and high-valent iron oxide(Fe(Ⅳ)=O)were de-tected in the SAFe_(0.4)–C_(3)N_(4)/PMS system through free radical capture experiments.Further experiments on the quenching of active species and a methyl phenyl sulfoxide probe confirmed that 1O_(2) and Fe(Ⅳ)=O played dom-inant roles.Additionally,the change in the current response after adding PMS and phenol in succession proved that a direct electron transfer path between organic matter and the catalyst surface was unlikely to exist in the SAFe_(0.4)–C_(3)N_(4)/PMS/Phenol degradation system.This study provides a new demonstration of the catalytic mech-anism of single-atom catalysts.
文摘Mitochondria are the central organelles that allow eukaryotic cells to efficiently convert nutrients into energy for cellular functions such as anabolic reactions,movement,and regulation.A reduction in the number of mitochondria or the occurrence of dysfunctional mitochondria leads to serious diseases such as the Leigh syndrome.However,such changes have also been connected to Alzheimer’s disease(AD)and many more diseases of different organ systems and occur during the aging process.Mitochondria are,therefore.
文摘Sliver defects are a group of low-to-medium angle misoriented grains in Ni-based single crystal superalloys that have received more attention in recent years.Occurrence of these defects can negatively affect the mechanical properties of single crystal components.Therefore,studying the mechanisms of sliver formation and its effects on the final properties of alloys is of great importance.In this article,recent studies on the sliver defects were reviewed.Accordingly,the mechanisms of sliver formation as well as factors contributing to sliver initiation were studied.Additionally,effects of slivers on the mechanical properties of single crystal superalloys were discussed.Dendrite deformation and dendrite fracture are the main mechanisms for the sliver formation.This is a consequence of local stress concentration on dendrites during solidification.Therefore,locations such as inclusions,pores,geometrically complex areas,mould walls,freckle channels,etc.can be considered as the potential factors that promote the sliver initiation.Sliver formation significantly degrades the creep life of single-crystal superalloys.Studies have shown that when crystallographic misorientation exceeds approximately15°,creep life can be reduced by up to 47%.Despite the absence of a standardized criterion for predicting or preventing sliver initiation and propagation,their occurrence can be minimized through optimization of solidification parameters,careful grain selection,proper casting geometry design,and rigorous control of material purity and equipment conditions.
基金supported by the National Natural Science Foundation of China(Grant No.11704301)the Natural Science Basic Research Plan in Shaanxi Province of China(Program No.2022JM212)supported by the Ministry of Science and Higher Education of the Russian Federation(FSEG-2023-0016).
文摘High-performance lead-free piezoelectric single crystals are urgently needed for next-generation actuators and transducers.In this study,we reveal that a compositionally driven tetragonal-pseudocubic(T-PC)phase boundary,in conjunction with an octahedral order-disorder tilting transition,significantly enhances the piezoelectric response in Nb^(5+)-substitution(Bi_(0.48)Na_(0.425)K_(0.055)Ba_(0.04))(Ti_(0.98)Nb_(0.02))O_(3)(BNKBT-2Nb)single crystals.The crystal achieves an outstanding piezoelectric coefficient of d33=662 pC/N at room temperature.In situ X-ray diffraction confirms an electric field-induced transition from the PC to T phase.Atomic-resolution HADDF-STEM analysis reveals an increase in the c/a ratio(c/a>1.01)on the local scale and ordered octahe-dral tilting of the a^(0)a^(0)c+type driven by the poling field.The single crystals exhibit excellent piezoelectric per-formance over a broad temperature range,achieving a peak d_(33) of 920 pC/N at approximately 92℃.Furthermore,the polar states exhibit a pronounced frequency dependence near the depolarization temperature.These findings provide critical insight into the structure-property relationship and offer a promising pathway for designing advanced lead-free piezoelectric crystals for functional electromechanical applications.
基金financially supported by the National Science and Technology Major Project of China(No.2019-VII-0019-0161 and No.2019-VII-0004-0144)the National Natural Science Foundation of China(No.92360302)the Shandong Provincial Natural Science Foundation of China(No.ZR2021QE103)。
文摘Turbine blades,due to their intricate geometry,are exposed to multiaxial stresses during operation.Consequently,it is imperative to examine the anisotropy of their stress-rupture behavior across various testing scenarios,particularly under high-temperature conditions.Stress-rupture behavior of a Ni-based single crystal superalloy was investigated under a load varying from 100 MPa to 137 MPa at 1,100℃ for both[001]-and[111]-orientated specimens.Results demonstrate that the rupture behavior of[111]-orientated specimens exhibits obviously higher sensitive to applied stress compared to[001]-orientated specimens.This difference is primarily attributed to the orientation dependentγ'coarsening behavior and distinct dislocation interactions atγ/γ'interfaces.In[001]-oriented specimens,plate-likeγ/γ'rafts rapidly form alongside well-developed interfacial dislocation networks,where theγ/γ'misfit stress dominates the microstructural evolution.In contrast,the[111]-orientated specimens exhibit retained,coarsenedγ'precipitates embedded within theγmatrix,accompanied by poorly developed interfacial dislocation networks.
基金financial support provided by the National Natural Science Foundation of China(Grant No.12302472)the Science and Technology Support Program of Jiangsu Province(Grant No.BK20230874)+2 种基金the Aeronautical Science Fund(ASF)(Grant No.2023Z057052005)the Research Fund of State Key Laboratory of Mechanics and Control for Aerospace Structures(Nanjing University of Aeronautics and Astronautics)(Grant No.MCAS-I-0124G02)the funding received from Jiangsu Hanvo Safety Product Co.,Ltd。
文摘High-performance fiber fabrics and composites experienced transverse compression deformation at ultrahigh strain rates near the impact point when subjected to high-velocity impacts,which significantly affected their ballistic limits.In this paper,a fiber-scale experimental method for characterizing ultrahigh strain-rate transverse compression behavior was proposed.To begin with,in order to measure the extremely low stress and strain in small specimens,the conventional Hopkinson bar was reduced to the hundred-micron scale,thereby achieving wave impedance matching with single fibers.In addition,tangential and normal laser Doppler velocimetry(LDV)methods were employed to realize non-contact,high-precision,and high-speed axial velocity measurements of micron-scale incident and transmission bars,respectively.Meanwhile,a microscopic observation system was used to facilitate the installation of miniature fiber samples.The experimental setup and procedures were introduced,and the system accuracy was verified through sample-free loading tests based on one-dimensional stress wave propagation theory.Dynamic compression experiments on Graphene-UHMWPE fibers were carried out,followed by post-compression microstructural characterization via scanning electron microscopy(SEM).Results demonstrated that successful mechanical characterization was achieved at strain rates exceeding 105,an order of magnitude higher than the previously reported maximum rates.Furthermore,during the loading process,the fibers underwent uniform compression deformation while exhibiting pronounced strain-rate effects.This method offers a novel approach for dynamic mechanical characterization of microscale single fibers,enabling the development of comprehensive strain-ratedependent material models to guide the design of advanced composites and high-performance fibers.
基金supported by the Yunnan Provincial Department of Education University-Hospital Joint Special Project(Grant No.XYLH202338)the National Health Commission Capacity Building and Continuing Education Center Project(Grant No.GWJJMB202510024141).
文摘Overview of diabetic gastroparesis Diabetic gastroparesis(DGP)is a common gastrointestinal complication of diabetes mellitus,characterized primarily by delayed gastric emptying.With the rising prevalence of diabetes,the incidence of DGP has increased annually,currently affecting approximately 50%of diabetic patients[1].Its main clinical manifestations include belching,nausea,vomiting,abdominal distension,and anorexia,which not only severely impair patients’quality of life but also trigger serious complications such as blood glucose fluctuations[2].Diagnosis primarily relies on clinical symptoms,exclusionary testing,and gastric emptying scintigraphy.
基金financial support of the National Natural Science Foundation of China(32102016)the Taishan Industrial Experts Program,Beijing Postdoctoral Research Foundation(2323ZZ122).
文摘The increase in human population has led to imminent pressures to develop new edible proteins with decreased environmental footprints.The most promising approach involves the production of single cell protein(SCP)from yeasts,which have been utilized in a wide variety of foods for thousands of years.In this study,102 yeast strains isolated from traditional fermented pork(Nanx Wudl)were investigated for their potential as SCP producer for the first time.Based on preliminary screening,Saccharomyces cerevisiae Y70 and Candida parapsilosis H5Y13,both showing high protein content and excellent growth capability,were selected for further analysis via 4D-DIA proteomics technology.Proteomic analysis indicated that the oxidative metabolism pathways,including TCA cycle,oxidative phosphorylation and pentose phosphate pathway,may have a significant impact on global protein synthesis and production.This study provides useful information for selecting SCP-producing yeast from Chinese fermented meat products and contribute to a deeper understanding of the underlying metabolic mechanisms behind global protein synthesis in yeast.Furthermore,these findings also provide potential molecular targets for genetic engineering modifications in yeast,aimed at constructing highly efficient cell factories for protein production.
基金financially supported by the Program for the Development of Science and Technology of Jilin Province(No.20240101004JJ)the National Natural Science Foundation of China(No.22409165)+4 种基金the National Foreign Experts Program of the Ministry of Human Resources and Social Security(No.Y20240003)the Shaanxi Province Talent Programfinancially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB0600000,XDB0600100,XDB0600200,XDB0600300,XDB0600400)Liaoning Binhai Laboratory(No.LILBLB-2023-04)Dalian Revitalization Talents Program(No.2022RG01)。
文摘Exploring the influence of the coordination environment of single-atom catalysts(SACs)on the electrochemical CO_(2)reduction reaction is vital for assessing the reaction mechanism and structure-performance relationship.However,it is challenging to engineer the coordination configuration of isolated active metal atoms precisely.Herein,we strategically manipulate the coordination number of the Co-N_(x) configuration by simply changing the order of adding the metal precursor toward improved CO_(2)electrolysis performance.Compared with the symmetric Co-N_(4)coordination,the asymmetric Co-N_(3)coordination leads to reinforced Co-N interaction and downshifted 3d orbital energy toward the Fermi level of the active Co sites,promoting the activation of CO_(2)molecules and the formation of critical intermediate^(*)COOH.The as-designed Co-N_(3)SAC displays excellent Faradaic efficiency(FE)of 98.4%for CO_(2)-to-CO conversion at a low potential of-0.80 V,together with decent FE over a wide potential range(-0.50 V to-1.10 V)and high durability.This study presents an ideal platform to manipulate the coordination number of atomically dispersed metal catalysts and provides a fundamental understanding of coordination configurationperformance correlation for CO_(2)electroreduction.
文摘Alzheimer’s disease(AD)is the most common form of dementia.In addition to the lack of effective treatments,there are limitations in diagnostic capabilities.The complexity of AD itself,together with a variety of other diseases often observed in a patient’s history in addition to their AD diagnosis,make deciphering the molecular mechanisms that underlie AD,even more important.Large datasets of single-cell RNA sequencing,single-nucleus RNA-sequencing(snRNA-seq),and spatial transcriptomics(ST)have become essential in guiding and supporting new investigations into the cellular and regional susceptibility of AD.However,with unique technology,software,and larger databases emerging;a lack of integration of these data can contribute to ineffective use of valuable knowledge.Importantly,there was no specialized database that concentrates on ST in AD that offers comprehensive differential analyses under various conditions,such as sex-specific,region-specific,and comparisons between AD and control groups until the new Single-cell and Spatial RNA-seq databasE for Alzheimer’s Disease(ssREAD)database(Wang et al.,2024)was introduced to meet the scientific community’s growing demand for comprehensive,integrated,and accessible data analysis.
基金financially supported by the National Natural Science Foundation of China (No. 22579095)the Beijing-Tianjin-Hebei Basic Research Cooperation Special Project (B2024204027)+2 种基金the Youth Top-notch Talent Foundation of Hebei Provincial Universities (BJK2022023)the Natural Science Foundation of Hebei Province (B2023204006)the talent training project of Hebei province (No. B20231004)。
文摘The rate capability and cycling stability of sodium metal batteries taking FeS_(2) or sulfur as cathode are limited due to their low reaction kinetics and severe shuttle effect.Herein,we rationally design a novel single-atom-dispersed S_(2)-FeNC/FeS_(2) nanocluster heterojunction embedded in carbon spheres(SFNC/FeS_(2)) for the electrode material of sodium metal batteries.Interestingly,during the discharging process,the Na^(+) is inserted into FeS_(2) to generate Na_(2)S,as well as the unique electrochemical reaction between S_(2)-FeNC and Na^(+) to form Na_(2)S.Meanwhile,the FeNC can adsorb Na_(2)S and catalyze the conversion from Na_(2)S and Fe to FeS_(2) or from Na_(2)S and FeNC to S_(2)-FeNC for suppressing the shuttle effect and promoting the distinct hybrid reversible electrochemical behavior,which improves performance tremendously.Notably,the SFNC/FeS_(2) electrode delivers a specific capacity of 338.7 mAh g^(-1) after superlong 2000 cycles at a current density of 5.0 A g^(-1) and achieves a high energy density of 430.1 Wh Kg^(-1) at a current density of 0.05 A g^(-1).This work presents a novel approach to studying sodium metal batteries with hybrid behavior for excellent high energy density and cycling stability.
基金supported by the National Natural Science Foundation of China(62303353,62273030,62573320)。
文摘Dear Editor,This letter studies the problem of stealthy attacks targeting stochastic event-based estimation,alongside proposing measures for their mitigation.A general attack framework is introduced,and the corresponding stealthiness condition is analyzed.To enhance system security,we advocate for a single-dimensional encryption method,showing that securing a singular data element is sufficient to shield the system from the perils of stealthy attacks.
基金financially supported by the Hunan Provincial Natural Science Foundation for Distinguished Young Scholars(2025JJ20019)the National Key R&D Program of China(2025YFE0107600)。
文摘Bismuth vanadate(BiVO_(4))is regarded as a promising photoanode for photoelectrochemical(PEC)water splitting.Despite its advantage in band gap and visible-light response,the BiVO_(4)exhibits an unsatisfactory achieving water splitting due to severe charge recombination.Herein,we elucidate an innovative approach involving the incorporation of single Ru atom with a CoFe-LDH cocatalyst(Ru_(0.51)-CoFe-LDH)and integrating it onto the BiVO_(4)semiconductor substrate.The resulting Ru_(0.51)-CoFe-LDH/BiVO_(4)photoanode film demonstrates commendable charge injection efficiency(76%)and charge collection efficiency(100%).Interestingly,the yield of hydrogen and oxygen increases linearly at a stoichiometric ratio of about 2:1,reaching 158.6 and 67.4μmol after140 min of irradiation,respectively.According to experimental characterization and density functional theory calculation,this remarkable performance results from single Ru atoms triggering the electron rearrangement of Ru_(0.51)-CoFe-LDH to engineer active sites and optimize interfacial energetics.Additionally,the negative shift of Ru_(0.51)-CoFe-LDH band edge gives rise to more conspicuous band bending of the n-n junction formed with BiVO_(4),expediting the separation and transfer of photogenerated electron-hole pairs at the interface.This work furnishes a new preparation perspective for PEC water splitting systems to construct single atoms in the semiconductor substrate.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSITRS2024-00345635 and RS-2021-NR060090)the Research Grant Council of the Hong Kong SAR(PolyU15302824)。
文摘Iron-based single-atom(SA)catalysts offer a promising alternative to noble-metal catalysts for the oxygen reduction reaction(ORR),yet their limited intrinsic activity and durability hinder practical energy device applications.Herein,we introduce a novel TiN/TiC-supported Fe SA catalyst(TiNC/Fe-NC)with a hierarchical heterostructure that synergistically enhances Fe-N_(x) site activity and accessibility.The TiNC/Fe-NC catalyst achieves outstanding ORR performances,with half-wave potentials(E_(1/2))of 0.852 V in acidic media and 0.942 V in alkaline media.Theoretical simulations reveal that strong electronic interaction and efficient charge transfer between TiNC and Fe-N_(x) sites optimize the adsorption energetics of key ORR intermediates,driving the enhanced activity.Remarkably,TiNC effectively scavenges reactive oxygen radicals generated at the Fe centers,ensuring exceptional durability with a minimal 28 mV loss in E_(1/2) after 10,000 cycles at 80℃in acid media.In practical applications,TiNC/Fe-NC delivers peak power densities of 306 mW cm^(-2) in zinc-air battery and 732 mW cm^(-2) in proton exchange membrane fuel cells,with remarkable long-term stability.This work establishes TiNC/Fe-NC as a highperformance,durable catalyst for advanced energy storage and conversion technologies.
