Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties durin...Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties during recognition reaction process,which is closely related to their ICT characteristics.1,8-Naphthalimide is known as a typical fluorophore with desirable ICT property when functionalized with an electron-donating moiety at the para-position of the naphthalene chromophore.Although the photophysical properties of para-substituted 1,8-naphthalimide have been well studied,its meta-substituted counterpart has not been fully evaluated since the meta-position is conventionally thought to be weakly conjugated.Herein,combined experimental and theoretical studies are performed which consistently indicate that stronger charge transfer(CT) is exhibited by the meta-amino substituted 1,8-naphthalimide(m-NH_(2)) compared to the para-amino substituted one(p-NH_(2)).The ratiometric response of fluorescence with significant changes in wavelength and intensity upon acetylation(m-NAc and p-NAc) can be attributed to the larger ICT and stronger-NH_(2) vibrations.This observation is further demonstrated by deuterium oxide experiments,viscosity experiments and quantum chemical calculations.The practical application of meta-amino-1,8-naphthalimide ICT-based probes is also confirmed.This research is expected to bring an in-depth understanding of π-conjugated systems with ICT characteristics,and facilitates the design of sensitive ICT fluorescent probes with meta-amino substitution.展开更多
A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,...A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,γ-difluoro-and γ-monofluoro-vinylacetic acids without stepwise acidification,exhibiting good functional group tolerance,broad scope,and facile scalability.Mechanism studies support that thiol plays the role of the hydrogen relay,which s a hydrogen atom through HAT and then outputs a proton via PT.This strategy also takes full advantage of formate for photocatalytic carboxylation reaction in a step-and atomeconomical way.展开更多
This study investigates the enhancement of convective heat transfer in a serpentine pipe using ferrofluid flow influenced by dual non-uniform magnetic sources.The primary objective is to improve thermal performance in...This study investigates the enhancement of convective heat transfer in a serpentine pipe using ferrofluid flow influenced by dual non-uniform magnetic sources.The primary objective is to improve thermal performance in compact cooling systems,such as those used in heat exchangers.A two-dimensional,steady-state Computational Fluid Dynamic(CFD)model is developed in ANSYS Fluent to simulate the behavior of an incompressible ferrofluid under applied constant heat flux and magnetic fields.The magnetic force is modeled using the Kelvin force,which acts on magnetized nanoparticles in response to spatially varying electromagnetic fields generated by two strategically positioned current-carrying wires.The effects of magnetic field strength,quantified by the magnetic number(Mn),on flow behavior and temperature distribution are thoroughly analyzed.The results indicate that increasing Mn leads to higher Nusselt numbers,demonstrating enhanced convective heat transfer.Secondary vortices induced by magnetic forcing improve fluid mixing,particularly in curved regions of the pipe.A mesh-independence study and model validation with benchmark data support the reliability of the numerical framework.This work highlights the potential of magnetic-field-assisted thermal control in energy-efficient cooling applications and provides a foundation for the further development of advanced ferrofluid-based heat transfer systems.展开更多
In this study,we meticulously designed a layered carbon-based catalytic material to induce the degradation of a series of organic pollutants by activating peroxymonosulfate(PMS) in the PMS-based advanced oxidation pro...In this study,we meticulously designed a layered carbon-based catalytic material to induce the degradation of a series of organic pollutants by activating peroxymonosulfate(PMS) in the PMS-based advanced oxidation processes(AOPs).Results indicated that the silicon and oxygen elements from the montmorillonite were incorporated into the catalyst matrix to form the Si-O-C structure.It was notable that the layered carbonaceous material with Si-O-C structure exhibited an outstanding catalytic effect on the synthesized layered catalytic material array,achieving over 90 % removal rate of most pollutants within 60 min.It was notable that the layered carbonaceous material with Si-O-C structure exhibited an outstanding catalytic effect on the synthesized layered catalytic material array.The salt bridge system confirmed that pollutants can provide electrons to the Si-O-C/PMS system,and we verified that the electron transfer process(ETP) mechanism was the main pathway for the degradation of pollutants in the Si-O-C/PMS system via the open-circuit potential analysis.In combination with the structural properties of different pollutants,we discovered that electron-donating pollutants can supply more electrons to the Si-O-C/PMS system,thereby enhancing the ETP process.The findings of this study are anticipated to advance the development and practical application of layered carbonaceous materials-based catalysts and support the design and implementation of nanoconfined catalysts in the field of AOPs.展开更多
The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for syn...The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for synthesizing thioesters primarily rely on the acylation of thiols,which produces substantial waste and requires malodorous,unstable sulfur sources.In this work,we introduce a photocatalyzed hydrogen transfer strategy that enables a three-component synthesis of thioesters using abundant primary alcohols,easily available alkenes and elemental sulfur under mild conditions.This protocol demonstrates broad applicability and high chemo-and regioselectivity for both primary alcohols and alkenes,highlighting the advantage and potential of photo-mediated hydrogen transfer in facilitating multicomponent reactions using primary alcohol and elemental sulfur feedstocks.展开更多
The severe shuttle effect and sluggish reaction kinetics in room-temperature sodium-sulfur(RT Na-S)batteries have been major bottlenecks hindering their practical application.To overcome these challenges,a straightfor...The severe shuttle effect and sluggish reaction kinetics in room-temperature sodium-sulfur(RT Na-S)batteries have been major bottlenecks hindering their practical application.To overcome these challenges,a straightforward reduction approach was employed to design three bimetallic alloy nanoparticles(FeNi,FeCo,and NiCo)supported on multistage porous carbon substrates.Experimental and theoretical calculations reveal that the charge transfer within the alloy catalyst influences the position of its d-band center and its degree of hybridization with sodium polysulfides(NaPSs).An increased charge transfer leads to a shift of the alloy’s d-band center closer to the Fermi energy level,thereby enhancing its adsorption and catalytic capabilities.Among the three alloy compositions,the FeNi alloy exhibits the highest charge transfer.Consequently,the FeNi alloy demonstrates the superior electrochemical performance,achieving a high reversible specific capacity of 848.2 mA h g^(−1),with an average capacity degradation rate of only 0.037%per cycle over 1000 cycles at 1.2 C.The S/FeNi/NC cathode exhibits a low electrolyte-to-sulfur(E/S)ratio of 6.6µL mg^(−1),while maintaining a high reversible specific capacity of 568.1 mA h g^(−1).This offers valuable insights for the application of alloy catalysts in the S/FeNi/NC cathode of RT Na-S batteries.展开更多
In recent years,with the rapid advancement of artificial intelligence,object detection algorithms have made significant strides in accuracy and computational efficiency.Notably,research and applications of Anchor-Free...In recent years,with the rapid advancement of artificial intelligence,object detection algorithms have made significant strides in accuracy and computational efficiency.Notably,research and applications of Anchor-Free models have opened new avenues for real-time target detection in optical remote sensing images(ORSIs).However,in the realmof adversarial attacks,developing adversarial techniques tailored to Anchor-Freemodels remains challenging.Adversarial examples generated based on Anchor-Based models often exhibit poor transferability to these new model architectures.Furthermore,the growing diversity of Anchor-Free models poses additional hurdles to achieving robust transferability of adversarial attacks.This study presents an improved cross-conv-block feature fusion You Only Look Once(YOLO)architecture,meticulously engineered to facilitate the extraction ofmore comprehensive semantic features during the backpropagation process.To address the asymmetry between densely distributed objects in ORSIs and the corresponding detector outputs,a novel dense bounding box attack strategy is proposed.This approach leverages dense target bounding boxes loss in the calculation of adversarial loss functions.Furthermore,by integrating translation-invariant(TI)and momentum-iteration(MI)adversarial methodologies,the proposed framework significantly improves the transferability of adversarial attacks.Experimental results demonstrate that our method achieves superior adversarial attack performance,with adversarial transferability rates(ATR)of 67.53%on the NWPU VHR-10 dataset and 90.71%on the HRSC2016 dataset.Compared to ensemble adversarial attack and cascaded adversarial attack approaches,our method generates adversarial examples in an average of 0.64 s,representing an approximately 14.5%improvement in efficiency under equivalent conditions.展开更多
Air-permeable and ultrathin conductive electrodes are essential for next-generation soft electronics,including breathable wearables,on-skin devices and biointegrated electronics.However,conventional metallization stra...Air-permeable and ultrathin conductive electrodes are essential for next-generation soft electronics,including breathable wearables,on-skin devices and biointegrated electronics.However,conventional metallization strategies,such as sputtering and ink-printing,often suffer from severe vertical charge leakage due to the porous and ultrathin characteristics of nanofibrous networks,leading to device short-circuiting,operational failure and limited vertical integration.Here,we present a solvent-selective dissolutionassisted transfer printing strategy to achieve surface-confined metallization of ultrathin,lightweight,and gas-permeable nanofibrous networks,enabling lateral conductivity while maintaining vertical insulation.This transfer printing process facilitates not only the rapid formation of conductive patterns on the surface of nanofibrous networks but also mechanical reinforcement through solvent evaporation-induced interlocked fiber-fiber welding.Meanwhile,the strategy preserves the high permeability of the nanofibrous networks and imparts a unique combination of surface conductivity(2Ωcm)and vertical insulativity(10^(11)Ωcm).The resulting anisotropic conductive networks enable low-voltage wearable heaters,high-sensitive pressure sensors,and ultralight temperature sensors.A pressure-temperature dual-modal sensing patch is further fabricated for intelligent grasping classification.The proposed surface-confined metallization strategy enables rapid fabrication of an anisotropic conductive network as a building block to construct air-permeable,ultrathin and lightweight wearable electronics.展开更多
Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong d...Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong dependence on large quantities of highquality samples,resulting in significantly low prediction accuracy of existing studies under data-scarce or crossregional prediction scenarios,which fail to meet practical application requirements.To address this issue,this study proposes an intelligent prediction model integrating transfer learning and a sampling optimization strategy,aiming to enhance the accuracy and applicability of seismic landslide susceptibility assessment.The model first improves the sample collection method through the sampling optimization strategy to enhance the precision and representativeness of training samples.This not only ensures the accuracy of origin area training but also further strengthens the model's predictive ability in the target area.Subsequently,it incorporates Transfer Component Analysis(TCA)to overcome the differences in environmental characteristics between the origin area and target area,and couples TCA with the Light GBM algorithm to construct the TCA-Light GBM model,realizing the assessment of seismic landslide susceptibility in sample-free areas.Validated through case studies of the Jiuzhaigou and Luding earthquakes,the results demonstrate that the proposed TCALight GBM transfer learning method exhibits excellent applicability in seismic landslide susceptibility prediction.After optimization with the TCA algorithm,the model's prediction performance in the target domain is significantly improved,with the AUC value increasing from 0.719 to 0.827,representing an increase of approximately 15.02%.This indicates that TCA technology can effectively alleviate the feature distribution discrepancy between the source domain and target domain,enhancing the model's generalization ability.The method is particularly suitable for scenarios with data scarcity and cross-regional prediction and can provide reliable technical support for the emergency response and risk prevention and control of seismic hazards.展开更多
Co-assembling chiral molecules with achiral compounds via non-covalent interactions like areneperfluoroarene(AP) interactions offers an effective approach for fabricating chiral functional materials.Herein,chiral mole...Co-assembling chiral molecules with achiral compounds via non-covalent interactions like areneperfluoroarene(AP) interactions offers an effective approach for fabricating chiral functional materials.Herein,chiral molecules L/D-PF1 and L/D-PF2 with pyrene groups were synthesized and its chiroptical properties upon co-assembly with achiral compound octafluoronaphthalene(OFN) through AP interaction were systemically studied.The co-assembly of L/D-PF1/OFN and L/D-PF2/OFN exhibited distinct chiroptical properties such as circular dichroism(CD) and circularly polarized luminescence(CPL) signals.Chirality transfer from the chirality center of L/D-PF1 and L/D-PF2 to the achiral OFN and chiral amplification were successfully achieved.Besides,no significant CPL signal was observed in the self-assembly of L/DPF1 or L/D-PF2 while co-assembly with OFN exhibited obvious CPL amplification induced by AP interaction.Notably,a reversal CD signal and CPL signal could be observed in L/D-PF2/OFN when the molar ratio changed from 1:1 to 1:2 while not found in L/D-PF1/OFN,indicating that that minor structural changes of molecules could cause large changes in assembly.In addition,a series of computational calculations were conducted to verify the AP interaction between L-PF1/L-PF2 and OFN.This work demonstrated that arene-perfluoroarene interaction could drive chiral transfer,chiral amplification and chiral inversion and provided a new method for the preparation of chiroptical materials.展开更多
Regenerative catalytic oxidizers(RCO)are widely used to remove volatile organic compounds(VOCs)due to their energy-saving and stability.In this study,a multi-component catalytic reaction model was constructed to numer...Regenerative catalytic oxidizers(RCO)are widely used to remove volatile organic compounds(VOCs)due to their energy-saving and stability.In this study,a multi-component catalytic reaction model was constructed to numerically investigate the reaction process of hydrocarbon-containing VOCs in RCO using computational fluid dynamics(CFD)simulation.To obtain the conversion characteristics of multi-component hydrocarbons,the effects of intake load,equivalence ratio,and the composition of multi-component hydrocarbons on the flow,heat transfer,and conversion rate of the reactor were analyzed.A feasibility study plan targeting the hard-to-convert components was also proposed.The results indicated that as the load increases,the conversion rates of the various components decrease,while the reaction rates increase.Moreover,increasing the flow velocity intensifies turbulence and enhances the collision frequency between the gas and the wall surfaces.This,in turn,amplifies the resistance effect of the porous medium.As the equivalence ratio of VOCs to oxygen increases,the oxygen-deficient condition leads to a decrease in the molecular weight of the hydrocarbons involved in the reaction.The reaction temperature also shows a downward trend.A comparative analysis of the catalytic combustion characteristics of multi-component VOCs and single-component gases reveals that adding ethane and propane can facilitate methane oxidation.展开更多
Endogenous hydrogen systems,consisting of metal–organic coordination catalysts and alcohols,have been widely applied for the transfer hydrogenation(TH)of biomass-derived carbonyl compounds in recent years.Metal-organ...Endogenous hydrogen systems,consisting of metal–organic coordination catalysts and alcohols,have been widely applied for the transfer hydrogenation(TH)of biomass-derived carbonyl compounds in recent years.Metal-organic coordination catalysts showed satisfactory ability of TH in the secondary alcohols,but most of them could not effectively employ the cheaper primary alcohols as hydrogen donors.Furthermore,they commonly contained high metal contents,which also led to low catalytic efficiency in significant measure.In this work,we constructed a novel magnesium single-atom catalyst(Mg-NC)with merely 0.37 wt%Mg by means of a combined self-assembly and pyrolysis strategy.The characterization results indicated that Mg was atomically dispersed and it was coordinated with four pyridinic-N in Mg-NC.Due to the obvious electron transfer from Mg to its coordinated pyridinic-N,Mg–N_(4)active centers displayed high Lewis acid-base strength with abundant content,which brought remarkable catalytic activity.When Mg-NC was used for the TH of 5-hydroxymethylfurfural(HMF)in ethanol(EtOH),2,5-bis(hydroxymethyl)furan(BHMF)yield was up to 96.3%with high productivity of 19.85 molBHMF mol_(Mg)^(−1)h^(−1)at 150°C for 5 h.More interestingly,the process of TH over Mg-NC in EtOH was proved to proceed via the hydrogen radical mechanism.Additionally,Mg-NC exhibited powerful catalytic universality;it could not only utilize other primary alcohols(such as n-propanol and n-butanol)as hydrogen donors,but also catalyze the TH of other carbonyl compounds(such as furfural,5-methylfurfural,benzaldehyde,cyclohexanone,and levulinic acid).Overall,this work offered some important clues and references to reinforce the hydrogen-supplying ability of primary alcohols in the TH of various biomass-derived carbonyl compounds to high-value fine chemicals.展开更多
Pulsed dynamic electrolysis(PDE),driven by renewable energy,has emerged as an innovative electrocatalytic conversion method,demonstrating significant potential in addressing global energy challenges and promoting sust...Pulsed dynamic electrolysis(PDE),driven by renewable energy,has emerged as an innovative electrocatalytic conversion method,demonstrating significant potential in addressing global energy challenges and promoting sustainable development.Despite significant progress in various electrochemical systems,the regulatory mechanisms of PDE in energy and mass transfer and the lifespan extension of electrolysis systems,particularly in water electrolysis(WE)for hydrogen production,remain insufficiently explored.Therefore,there is an urgent need for a deeper understanding of the unique contributions of PDE in mass transfer enhancement,microenvironment regulation,and hydrogen production optimization,aiming to achieve low-energy consumption,high catalytic activity,and long-term stability in the generation of target products.Here,this review critically examines the microenvironmental effects of PDE on energy and mass transfer,the electrode degradation mechanisms in the lifespan extension of electrolysis systems,and the key factors in enhancing WE for hydrogen production,providing a comprehensive summary of current research progress.The review focuses on the complex regulatory mechanisms of frequency,duty cycle,amplitude,and other factors in hydrogen evolution reaction(HER)performance within PDE strategies,revealing the interrelationships among them.Finally,the potential future directions and challenges for transitioning from laboratory studies to industrial applications are proposed.展开更多
Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics...Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics,and free electron radiation devices.Particularly,they are promising platforms for studying thermionic emission.It is illustrated that using vdW heterostructure-based thermionic emission can enhance heat transfer in vacuum devices.As a proof of concept,the approach is demonstrated to offer a promising solution for the long-standing overheating issue in X-ray tubes.Specifically,it is shown that the saturated target temperature of a 2000 W X-ray tube can be reduced from around 1200℃ to 490℃.Additionally,it is also demonstrated that by reducing the height of the Schottky barrier formed in the vdW heterostructures,the thermionic cooling performance can be enhanced.The findings pave the way for the development of high-power X-ray tubes.展开更多
As structural damage patterns and service environments become more complex,digital twin-based structural health monitoring,with its unique advantages,can compensate for the limitations of data-driven methods regarding...As structural damage patterns and service environments become more complex,digital twin-based structural health monitoring,with its unique advantages,can compensate for the limitations of data-driven methods regarding data dependency and model interpretability.However,it still faces challenges in modeling complexity,simulation accuracy,and discrepancies between real and virtual features.This study proposes a balanced fidelity digital twin for structural damage monitoring based on Lamb wave multilevel feature enhancement and adaptive space interaction.Firstly,multilevel refined features are extracted from few-shot guided wave signals obtained in physical and digital space,and the adversarial synthetic balancing algorithm is proposed for feature enhancement.Additionally,the learning phase of the damage monitoring model based on the feature-mapping convolutional network is driven by virtual samples of readily accessible balanced fidelity in digital space.To reduce the feature distributional difference between the two spaces,an interactive transfer approach is introduced to establish a shared feature digital twin space.Overall,this study provides a feasible technique to enhance the accessibility and generalizability of digital twins for real engineering structures.展开更多
Triclosan(TCS) poses harmful risks to ecosystems and human health owing to its endocrine-disrupting effects.Therefore,developing an efficient and sustainable technology to degrade TCS is urgently needed.Herein,cobalt ...Triclosan(TCS) poses harmful risks to ecosystems and human health owing to its endocrine-disrupting effects.Therefore,developing an efficient and sustainable technology to degrade TCS is urgently needed.Herein,cobalt oxyhydroxide @covalent organic frameworks(CoOOH@COFs) S-scheme heterojunction was synthesized,which combined the visible-light-driven photocatalysis and peroxymonosulfate(PMS) activation to synergistically generate abundant reactive oxygen species(ROSs) for TCS degradation.The degradation efficiency of TCS reached 100 % within 8 min in the Vis-CoOOH@COFs/PMS system,and the reaction rate constant was 0.456 min^(-1),which was nearly 1.90 and 2.85 times that of single Co OOH and COFs,and2.36 times that under dark condition,respectively.The density functional theory(DFT) calculations confirmed the energy band bending of CoOOH@COFs and S-scheme charge transport from COFs to Co OOH.Both experimental and theoretical analyses indicated that Co OOH@COFs in photocatalytic-PMS activation systems synergistically facilitated photo-generated carrier separation,enhanced interfacial electron transfer,accelerated PMS activation,and generated multiple ROSs.In particular,photogenerated electrons(e^(-))accelerated the Co(Ⅲ)/Co(Ⅱ) redox cycle,while the PMS captured the e-,which significantly decreased the charge combination of Co OOH@COFs.Radicals(O_(2)^(·-),^(·)OH,and SO_(4)^(·-)) and non-radicals(such as ^(1)O_(2),h^(+),and e^(-)) were both presented in the Vis-CoOOH@COFs/PMS system,with O_(2)^(-) playing a dominant role in TCS degradation.Furthermore,the pathway of TCS degradation and toxicity of intermediates were explored by DFT calculation and transformation product identification.Importantly,the environmentally friendly CoOOH@COFs S-scheme heterojunction exhibited excellent stability and reusability.In conclusion,this study innovatively designed an S-scheme heterojunction in the photocatalytic-PMS activation system,providing guidance and theoretical support for efficient and eco-friendly wastewater treatment.展开更多
Recent advancements in Zn-halogen batteries have focused on enhancing the adsorptive or catalytic capability of host materials and stabilizing complex intermediates with electrolyte additives,while the halogen-ion ele...Recent advancements in Zn-halogen batteries have focused on enhancing the adsorptive or catalytic capability of host materials and stabilizing complex intermediates with electrolyte additives,while the halogen-ion electrolyte modifications exhibit strong potential for integrated interfacial regulation.Herein,we design an electrically insulating rigid electrolyte container to immobilize a liquid halogen-ion electrolyte for separator-free Zn-halogen batteries with customizable electron transfer.Robust hydrogen bonding of hydroxyl groups in SiO_(2)with fluorinated moieties in PVDF-hfp regulates Zn^(2+)solvation and suppresses H_(2)O activity,while multi-channels formed by microcracks and interparticle gaps not only enhance mass transfer but also buffer interfacial electric field,jointly enabling a durable Zn plating/stripping.Effective confinement of intermediates also ensures the high reversibility across single-(I^(-)/I0),double-(I^(-)/I0/I^(-)),and triple-(I^(-)/I0/I^(-),Cl-/Cl0)electron transfer mechanisms at cathode,as evidenced by the double-electron transfer systems exhibiting a low capacity decay rate of 0.02‰over 4500 cycles at 10 mA cm^(-2)and a high areal capacity of 11.9 mAh cm^(-2)at 2 mA cm^(-2).This work presents a novel“container engineering”approach to halogen-ion electrolyte design and provides fundamental insights into the relationships between redox reversibility and reaction kinetics.展开更多
The synthesis of propylene carbonate(PC)from CO_(2) and propylene oxide(PO)is a typical gas-liquid biphasic system,where gas-liquid mass transfer efficiency significantly influences CO_(2) cycloaddition reactions.Here...The synthesis of propylene carbonate(PC)from CO_(2) and propylene oxide(PO)is a typical gas-liquid biphasic system,where gas-liquid mass transfer efficiency significantly influences CO_(2) cycloaddition reactions.Here,we proposed a microchannel reaction system for the CO_(2) cycloaddition reaction catalyzed by ionic liquid within an aqueous environment.The effect of liquid flow rate,temperature and residence time on gas-liquid flow pattern,catalytic performance and mass transfer were systematically investigated.The results revealed that the PC generation rate reached 560.11 mmol·ml^(−1)·h^(−1)at a 50 cm of flow distance under reaction conditions of 105℃,2.5 MPa,QG=176 ml·min^(−1) and QL=0.3 ml·min^(−1).Variations in mass transfer rate and reaction rate at different flow distances were experimentally studied.The reaction efficiency gradually decreased with increasing flow distance,which were attributed to the reduction of mass transfer caused by decreasing bubble velocity.Optimizing bubble velocity at an appropriate position enhanced reaction efficiency by improving mass transfer,achieving a 97.7%PC yield within 2.85 min.Furthermore,a kinetic model coupling intrinsic kinetics with gas-liquid mass transfer was developed for CO_(2) cycloaddition reaction.The kinetic model was applied to predict PC reaction rates in microchannel reactors at various temperatures and liquid flow rates,achieving an average relative error of 9.6%.展开更多
The radiative heat flux of the plume from reusable rockets is a critical parameter during the launch and return processes.This paper proposes a method for calculating radiative heat flux with higher accuracy than prev...The radiative heat flux of the plume from reusable rockets is a critical parameter during the launch and return processes.This paper proposes a method for calculating radiative heat flux with higher accuracy than previously reported for a recoverable nine-engine liquid-propellant rocket.Based on the Radiative Transfer Equation(RTE),this study employs the discrete transfer method to solve the transient RTE problem using physical properties to describe the problem while avoiding the need to directly solve mathematical equations.The proposed method can effectively determine the radiative heat flux of the flow field and is applicable to problems involving various geometries.Calculations reveal that during the ascent phase of the rocket,the radiative heat flux at the base of the vehicle reaches its maximum in the initial stages of the lift-off,reaching a maximum of~50 kW/m^(2),which is 2.24 times the maximum value during the return phase.During the deceleration stage of re-entry into the atmosphere,the maximum radiative heat flux recorded on the sidewall of the rocket is 29.1 kW/m^(2);the maximum heat flux on the bottom surface is approximately 22.3 kW/m^(2),accounting for 76.6%of that on the rocket's sidewall.This provides a basis for the thermal protection design of the rocket's bottom and walls as well as for the thermal management of cryogenic propellant tanks.Future research will involve ground engine testing and flight experiments to further validate the proposed model.展开更多
In this paper,we propose a systematic approach for accelerating finite element-type methods by machine learning for the numerical solution of partial differential equations(PDEs).The main idea is to use a neural netwo...In this paper,we propose a systematic approach for accelerating finite element-type methods by machine learning for the numerical solution of partial differential equations(PDEs).The main idea is to use a neural network to learn the solution map of the PDEs and to do so in an element-wise fashion.This map takes input of the element geometry and the PDE’s parameters on that element,and gives output of two operators:(1)the in2out operator for inter-element communication,and(2)the in2sol operator(Green’s function)for element-wise solution recovery.A significant advantage of this approach is that,once trained,this network can be used for the numerical solution of the PDE for any domain geometry and any parameter distribution without retraining.Also,the training is significantly simpler since it is done on the element level instead on the entire domain.We call this approach element learning.This method is closely related to hybridizable discontinuous Galerkin(HDG)methods in the sense that the local solvers of HDG are replaced by machine learning approaches.Numerical tests are presented for an example PDE,the radiative transfer or radiation transport equation,in a variety of scenarios with idealized or realistic cloud fields,with smooth or sharp gradient in the cloud boundary transition.Under a fixed accuracy level of 10^(−3) in the relative L^(2) error,and polynomial degree p=6 in each element,we observe an approximately 5 to 10 times speed-up by element learning compared to a classical finite element-type method.展开更多
基金financially supported by National Key Research and Development Programs (Nos.2022YFD1700403 and 2023YFD1700303)National Natural Science Foundation of China (Nos.12274128 and 12250003)+2 种基金Shanghai Rising-Star Program (No.21QA1402600)the support of NYU-ECNU Center for Computational Chemistry at NYU Shanghaithe University of Bath and the Open Research Fund of the School of Chemistry and Chemical Engineering,Henan Normal University (No.2020ZD01) for support。
文摘Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties during recognition reaction process,which is closely related to their ICT characteristics.1,8-Naphthalimide is known as a typical fluorophore with desirable ICT property when functionalized with an electron-donating moiety at the para-position of the naphthalene chromophore.Although the photophysical properties of para-substituted 1,8-naphthalimide have been well studied,its meta-substituted counterpart has not been fully evaluated since the meta-position is conventionally thought to be weakly conjugated.Herein,combined experimental and theoretical studies are performed which consistently indicate that stronger charge transfer(CT) is exhibited by the meta-amino substituted 1,8-naphthalimide(m-NH_(2)) compared to the para-amino substituted one(p-NH_(2)).The ratiometric response of fluorescence with significant changes in wavelength and intensity upon acetylation(m-NAc and p-NAc) can be attributed to the larger ICT and stronger-NH_(2) vibrations.This observation is further demonstrated by deuterium oxide experiments,viscosity experiments and quantum chemical calculations.The practical application of meta-amino-1,8-naphthalimide ICT-based probes is also confirmed.This research is expected to bring an in-depth understanding of π-conjugated systems with ICT characteristics,and facilitates the design of sensitive ICT fluorescent probes with meta-amino substitution.
基金supported by the National Natural Science Foundation of China (22472031,U24A20567,22032002)the 111 Project。
文摘A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,γ-difluoro-and γ-monofluoro-vinylacetic acids without stepwise acidification,exhibiting good functional group tolerance,broad scope,and facile scalability.Mechanism studies support that thiol plays the role of the hydrogen relay,which s a hydrogen atom through HAT and then outputs a proton via PT.This strategy also takes full advantage of formate for photocatalytic carboxylation reaction in a step-and atomeconomical way.
文摘This study investigates the enhancement of convective heat transfer in a serpentine pipe using ferrofluid flow influenced by dual non-uniform magnetic sources.The primary objective is to improve thermal performance in compact cooling systems,such as those used in heat exchangers.A two-dimensional,steady-state Computational Fluid Dynamic(CFD)model is developed in ANSYS Fluent to simulate the behavior of an incompressible ferrofluid under applied constant heat flux and magnetic fields.The magnetic force is modeled using the Kelvin force,which acts on magnetized nanoparticles in response to spatially varying electromagnetic fields generated by two strategically positioned current-carrying wires.The effects of magnetic field strength,quantified by the magnetic number(Mn),on flow behavior and temperature distribution are thoroughly analyzed.The results indicate that increasing Mn leads to higher Nusselt numbers,demonstrating enhanced convective heat transfer.Secondary vortices induced by magnetic forcing improve fluid mixing,particularly in curved regions of the pipe.A mesh-independence study and model validation with benchmark data support the reliability of the numerical framework.This work highlights the potential of magnetic-field-assisted thermal control in energy-efficient cooling applications and provides a foundation for the further development of advanced ferrofluid-based heat transfer systems.
基金supported by National Natural Science Foundation of China (Nos.52170086,22476116,52074176)Natural Science Foundation of Shandong Province (Nos.ZR2021ME013,ZR2024ME156,ZR2022QB250)。
文摘In this study,we meticulously designed a layered carbon-based catalytic material to induce the degradation of a series of organic pollutants by activating peroxymonosulfate(PMS) in the PMS-based advanced oxidation processes(AOPs).Results indicated that the silicon and oxygen elements from the montmorillonite were incorporated into the catalyst matrix to form the Si-O-C structure.It was notable that the layered carbonaceous material with Si-O-C structure exhibited an outstanding catalytic effect on the synthesized layered catalytic material array,achieving over 90 % removal rate of most pollutants within 60 min.It was notable that the layered carbonaceous material with Si-O-C structure exhibited an outstanding catalytic effect on the synthesized layered catalytic material array.The salt bridge system confirmed that pollutants can provide electrons to the Si-O-C/PMS system,and we verified that the electron transfer process(ETP) mechanism was the main pathway for the degradation of pollutants in the Si-O-C/PMS system via the open-circuit potential analysis.In combination with the structural properties of different pollutants,we discovered that electron-donating pollutants can supply more electrons to the Si-O-C/PMS system,thereby enhancing the ETP process.The findings of this study are anticipated to advance the development and practical application of layered carbonaceous materials-based catalysts and support the design and implementation of nanoconfined catalysts in the field of AOPs.
基金National Natural Science Foundation of China (Nos.22071185 and 22271224)the Fundamental Research Funds for the Central Universities (No.2042019kf0008)Wuhan University startup funding for financial support。
文摘The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for synthesizing thioesters primarily rely on the acylation of thiols,which produces substantial waste and requires malodorous,unstable sulfur sources.In this work,we introduce a photocatalyzed hydrogen transfer strategy that enables a three-component synthesis of thioesters using abundant primary alcohols,easily available alkenes and elemental sulfur under mild conditions.This protocol demonstrates broad applicability and high chemo-and regioselectivity for both primary alcohols and alkenes,highlighting the advantage and potential of photo-mediated hydrogen transfer in facilitating multicomponent reactions using primary alcohol and elemental sulfur feedstocks.
基金supported by Shaanxi Fundamental Science Research Project for Chemistry and Biology(23JHQ011)Natural Science Foundation of Shaanxi(2024JC-YBMS-115)Natural Science Basic Research Plan in Shaanxi Province of China(2025JC-YBMS-141)。
文摘The severe shuttle effect and sluggish reaction kinetics in room-temperature sodium-sulfur(RT Na-S)batteries have been major bottlenecks hindering their practical application.To overcome these challenges,a straightforward reduction approach was employed to design three bimetallic alloy nanoparticles(FeNi,FeCo,and NiCo)supported on multistage porous carbon substrates.Experimental and theoretical calculations reveal that the charge transfer within the alloy catalyst influences the position of its d-band center and its degree of hybridization with sodium polysulfides(NaPSs).An increased charge transfer leads to a shift of the alloy’s d-band center closer to the Fermi energy level,thereby enhancing its adsorption and catalytic capabilities.Among the three alloy compositions,the FeNi alloy exhibits the highest charge transfer.Consequently,the FeNi alloy demonstrates the superior electrochemical performance,achieving a high reversible specific capacity of 848.2 mA h g^(−1),with an average capacity degradation rate of only 0.037%per cycle over 1000 cycles at 1.2 C.The S/FeNi/NC cathode exhibits a low electrolyte-to-sulfur(E/S)ratio of 6.6µL mg^(−1),while maintaining a high reversible specific capacity of 568.1 mA h g^(−1).This offers valuable insights for the application of alloy catalysts in the S/FeNi/NC cathode of RT Na-S batteries.
文摘In recent years,with the rapid advancement of artificial intelligence,object detection algorithms have made significant strides in accuracy and computational efficiency.Notably,research and applications of Anchor-Free models have opened new avenues for real-time target detection in optical remote sensing images(ORSIs).However,in the realmof adversarial attacks,developing adversarial techniques tailored to Anchor-Freemodels remains challenging.Adversarial examples generated based on Anchor-Based models often exhibit poor transferability to these new model architectures.Furthermore,the growing diversity of Anchor-Free models poses additional hurdles to achieving robust transferability of adversarial attacks.This study presents an improved cross-conv-block feature fusion You Only Look Once(YOLO)architecture,meticulously engineered to facilitate the extraction ofmore comprehensive semantic features during the backpropagation process.To address the asymmetry between densely distributed objects in ORSIs and the corresponding detector outputs,a novel dense bounding box attack strategy is proposed.This approach leverages dense target bounding boxes loss in the calculation of adversarial loss functions.Furthermore,by integrating translation-invariant(TI)and momentum-iteration(MI)adversarial methodologies,the proposed framework significantly improves the transferability of adversarial attacks.Experimental results demonstrate that our method achieves superior adversarial attack performance,with adversarial transferability rates(ATR)of 67.53%on the NWPU VHR-10 dataset and 90.71%on the HRSC2016 dataset.Compared to ensemble adversarial attack and cascaded adversarial attack approaches,our method generates adversarial examples in an average of 0.64 s,representing an approximately 14.5%improvement in efficiency under equivalent conditions.
基金supported by the National Natural Science Foundation of China(22434007,22104021,52303075,22404102)the Taishan Young Scholar Program of Shandong Province(tsqnz20231235)+2 种基金the Natural Science Foundation of Shandong Province(ZR2024QB338,ZR2023QB227)the Higher Education Institutions Youth Innovation Team Plan of Shandong Province(2024KJH046)the Shandong Postdoctora1 Science Foundation(SDCX-ZG-202400279)。
文摘Air-permeable and ultrathin conductive electrodes are essential for next-generation soft electronics,including breathable wearables,on-skin devices and biointegrated electronics.However,conventional metallization strategies,such as sputtering and ink-printing,often suffer from severe vertical charge leakage due to the porous and ultrathin characteristics of nanofibrous networks,leading to device short-circuiting,operational failure and limited vertical integration.Here,we present a solvent-selective dissolutionassisted transfer printing strategy to achieve surface-confined metallization of ultrathin,lightweight,and gas-permeable nanofibrous networks,enabling lateral conductivity while maintaining vertical insulation.This transfer printing process facilitates not only the rapid formation of conductive patterns on the surface of nanofibrous networks but also mechanical reinforcement through solvent evaporation-induced interlocked fiber-fiber welding.Meanwhile,the strategy preserves the high permeability of the nanofibrous networks and imparts a unique combination of surface conductivity(2Ωcm)and vertical insulativity(10^(11)Ωcm).The resulting anisotropic conductive networks enable low-voltage wearable heaters,high-sensitive pressure sensors,and ultralight temperature sensors.A pressure-temperature dual-modal sensing patch is further fabricated for intelligent grasping classification.The proposed surface-confined metallization strategy enables rapid fabrication of an anisotropic conductive network as a building block to construct air-permeable,ultrathin and lightweight wearable electronics.
文摘Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong dependence on large quantities of highquality samples,resulting in significantly low prediction accuracy of existing studies under data-scarce or crossregional prediction scenarios,which fail to meet practical application requirements.To address this issue,this study proposes an intelligent prediction model integrating transfer learning and a sampling optimization strategy,aiming to enhance the accuracy and applicability of seismic landslide susceptibility assessment.The model first improves the sample collection method through the sampling optimization strategy to enhance the precision and representativeness of training samples.This not only ensures the accuracy of origin area training but also further strengthens the model's predictive ability in the target area.Subsequently,it incorporates Transfer Component Analysis(TCA)to overcome the differences in environmental characteristics between the origin area and target area,and couples TCA with the Light GBM algorithm to construct the TCA-Light GBM model,realizing the assessment of seismic landslide susceptibility in sample-free areas.Validated through case studies of the Jiuzhaigou and Luding earthquakes,the results demonstrate that the proposed TCALight GBM transfer learning method exhibits excellent applicability in seismic landslide susceptibility prediction.After optimization with the TCA algorithm,the model's prediction performance in the target domain is significantly improved,with the AUC value increasing from 0.719 to 0.827,representing an increase of approximately 15.02%.This indicates that TCA technology can effectively alleviate the feature distribution discrepancy between the source domain and target domain,enhancing the model's generalization ability.The method is particularly suitable for scenarios with data scarcity and cross-regional prediction and can provide reliable technical support for the emergency response and risk prevention and control of seismic hazards.
基金financially supported by the National Natural Science Foundation of China (Nos.22171165 and 22371170)Natural Science Foundation of Shandong Province (No.ZR2022MB080)Scientific and Technological Frontiers in Project of Henan Province(No.242102110192)。
文摘Co-assembling chiral molecules with achiral compounds via non-covalent interactions like areneperfluoroarene(AP) interactions offers an effective approach for fabricating chiral functional materials.Herein,chiral molecules L/D-PF1 and L/D-PF2 with pyrene groups were synthesized and its chiroptical properties upon co-assembly with achiral compound octafluoronaphthalene(OFN) through AP interaction were systemically studied.The co-assembly of L/D-PF1/OFN and L/D-PF2/OFN exhibited distinct chiroptical properties such as circular dichroism(CD) and circularly polarized luminescence(CPL) signals.Chirality transfer from the chirality center of L/D-PF1 and L/D-PF2 to the achiral OFN and chiral amplification were successfully achieved.Besides,no significant CPL signal was observed in the self-assembly of L/DPF1 or L/D-PF2 while co-assembly with OFN exhibited obvious CPL amplification induced by AP interaction.Notably,a reversal CD signal and CPL signal could be observed in L/D-PF2/OFN when the molar ratio changed from 1:1 to 1:2 while not found in L/D-PF1/OFN,indicating that that minor structural changes of molecules could cause large changes in assembly.In addition,a series of computational calculations were conducted to verify the AP interaction between L-PF1/L-PF2 and OFN.This work demonstrated that arene-perfluoroarene interaction could drive chiral transfer,chiral amplification and chiral inversion and provided a new method for the preparation of chiroptical materials.
基金supported by National Key Research&Development Program of China(2022YFB4101500).
文摘Regenerative catalytic oxidizers(RCO)are widely used to remove volatile organic compounds(VOCs)due to their energy-saving and stability.In this study,a multi-component catalytic reaction model was constructed to numerically investigate the reaction process of hydrocarbon-containing VOCs in RCO using computational fluid dynamics(CFD)simulation.To obtain the conversion characteristics of multi-component hydrocarbons,the effects of intake load,equivalence ratio,and the composition of multi-component hydrocarbons on the flow,heat transfer,and conversion rate of the reactor were analyzed.A feasibility study plan targeting the hard-to-convert components was also proposed.The results indicated that as the load increases,the conversion rates of the various components decrease,while the reaction rates increase.Moreover,increasing the flow velocity intensifies turbulence and enhances the collision frequency between the gas and the wall surfaces.This,in turn,amplifies the resistance effect of the porous medium.As the equivalence ratio of VOCs to oxygen increases,the oxygen-deficient condition leads to a decrease in the molecular weight of the hydrocarbons involved in the reaction.The reaction temperature also shows a downward trend.A comparative analysis of the catalytic combustion characteristics of multi-component VOCs and single-component gases reveals that adding ethane and propane can facilitate methane oxidation.
基金financially supported by the National Natural Science Foundation of China(U22A20421)the Qinglan Project of Jiangsu Province,the 533 Talent Program of Huaian City,and the College Students’Innovative Entrepreneurial Training Plan Program of Jiangsu Province(X202510323027).
文摘Endogenous hydrogen systems,consisting of metal–organic coordination catalysts and alcohols,have been widely applied for the transfer hydrogenation(TH)of biomass-derived carbonyl compounds in recent years.Metal-organic coordination catalysts showed satisfactory ability of TH in the secondary alcohols,but most of them could not effectively employ the cheaper primary alcohols as hydrogen donors.Furthermore,they commonly contained high metal contents,which also led to low catalytic efficiency in significant measure.In this work,we constructed a novel magnesium single-atom catalyst(Mg-NC)with merely 0.37 wt%Mg by means of a combined self-assembly and pyrolysis strategy.The characterization results indicated that Mg was atomically dispersed and it was coordinated with four pyridinic-N in Mg-NC.Due to the obvious electron transfer from Mg to its coordinated pyridinic-N,Mg–N_(4)active centers displayed high Lewis acid-base strength with abundant content,which brought remarkable catalytic activity.When Mg-NC was used for the TH of 5-hydroxymethylfurfural(HMF)in ethanol(EtOH),2,5-bis(hydroxymethyl)furan(BHMF)yield was up to 96.3%with high productivity of 19.85 molBHMF mol_(Mg)^(−1)h^(−1)at 150°C for 5 h.More interestingly,the process of TH over Mg-NC in EtOH was proved to proceed via the hydrogen radical mechanism.Additionally,Mg-NC exhibited powerful catalytic universality;it could not only utilize other primary alcohols(such as n-propanol and n-butanol)as hydrogen donors,but also catalyze the TH of other carbonyl compounds(such as furfural,5-methylfurfural,benzaldehyde,cyclohexanone,and levulinic acid).Overall,this work offered some important clues and references to reinforce the hydrogen-supplying ability of primary alcohols in the TH of various biomass-derived carbonyl compounds to high-value fine chemicals.
基金financially supported by the Key Research and Development Program of Heilongjiang Province(No.2024ZXJ03C06)National Natural Science Foundation of China(No.52476192,No.52106237)+1 种基金Natural Science Foundation of Heilongjiang Province(No.YQ2022E027)Technology Project of China Datang Technology Innovation Co.,Ltd(No.DTKC-2024-20610).
文摘Pulsed dynamic electrolysis(PDE),driven by renewable energy,has emerged as an innovative electrocatalytic conversion method,demonstrating significant potential in addressing global energy challenges and promoting sustainable development.Despite significant progress in various electrochemical systems,the regulatory mechanisms of PDE in energy and mass transfer and the lifespan extension of electrolysis systems,particularly in water electrolysis(WE)for hydrogen production,remain insufficiently explored.Therefore,there is an urgent need for a deeper understanding of the unique contributions of PDE in mass transfer enhancement,microenvironment regulation,and hydrogen production optimization,aiming to achieve low-energy consumption,high catalytic activity,and long-term stability in the generation of target products.Here,this review critically examines the microenvironmental effects of PDE on energy and mass transfer,the electrode degradation mechanisms in the lifespan extension of electrolysis systems,and the key factors in enhancing WE for hydrogen production,providing a comprehensive summary of current research progress.The review focuses on the complex regulatory mechanisms of frequency,duty cycle,amplitude,and other factors in hydrogen evolution reaction(HER)performance within PDE strategies,revealing the interrelationships among them.Finally,the potential future directions and challenges for transitioning from laboratory studies to industrial applications are proposed.
基金supported by National Natural Science Foundation of China(61921002 and 92163204)。
文摘Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics,and free electron radiation devices.Particularly,they are promising platforms for studying thermionic emission.It is illustrated that using vdW heterostructure-based thermionic emission can enhance heat transfer in vacuum devices.As a proof of concept,the approach is demonstrated to offer a promising solution for the long-standing overheating issue in X-ray tubes.Specifically,it is shown that the saturated target temperature of a 2000 W X-ray tube can be reduced from around 1200℃ to 490℃.Additionally,it is also demonstrated that by reducing the height of the Schottky barrier formed in the vdW heterostructures,the thermionic cooling performance can be enhanced.The findings pave the way for the development of high-power X-ray tubes.
基金supported by the National Natural Science Foundation of China(Grant Nos.No.U2141245,11972314,11472308)。
文摘As structural damage patterns and service environments become more complex,digital twin-based structural health monitoring,with its unique advantages,can compensate for the limitations of data-driven methods regarding data dependency and model interpretability.However,it still faces challenges in modeling complexity,simulation accuracy,and discrepancies between real and virtual features.This study proposes a balanced fidelity digital twin for structural damage monitoring based on Lamb wave multilevel feature enhancement and adaptive space interaction.Firstly,multilevel refined features are extracted from few-shot guided wave signals obtained in physical and digital space,and the adversarial synthetic balancing algorithm is proposed for feature enhancement.Additionally,the learning phase of the damage monitoring model based on the feature-mapping convolutional network is driven by virtual samples of readily accessible balanced fidelity in digital space.To reduce the feature distributional difference between the two spaces,an interactive transfer approach is introduced to establish a shared feature digital twin space.Overall,this study provides a feasible technique to enhance the accessibility and generalizability of digital twins for real engineering structures.
文摘Triclosan(TCS) poses harmful risks to ecosystems and human health owing to its endocrine-disrupting effects.Therefore,developing an efficient and sustainable technology to degrade TCS is urgently needed.Herein,cobalt oxyhydroxide @covalent organic frameworks(CoOOH@COFs) S-scheme heterojunction was synthesized,which combined the visible-light-driven photocatalysis and peroxymonosulfate(PMS) activation to synergistically generate abundant reactive oxygen species(ROSs) for TCS degradation.The degradation efficiency of TCS reached 100 % within 8 min in the Vis-CoOOH@COFs/PMS system,and the reaction rate constant was 0.456 min^(-1),which was nearly 1.90 and 2.85 times that of single Co OOH and COFs,and2.36 times that under dark condition,respectively.The density functional theory(DFT) calculations confirmed the energy band bending of CoOOH@COFs and S-scheme charge transport from COFs to Co OOH.Both experimental and theoretical analyses indicated that Co OOH@COFs in photocatalytic-PMS activation systems synergistically facilitated photo-generated carrier separation,enhanced interfacial electron transfer,accelerated PMS activation,and generated multiple ROSs.In particular,photogenerated electrons(e^(-))accelerated the Co(Ⅲ)/Co(Ⅱ) redox cycle,while the PMS captured the e-,which significantly decreased the charge combination of Co OOH@COFs.Radicals(O_(2)^(·-),^(·)OH,and SO_(4)^(·-)) and non-radicals(such as ^(1)O_(2),h^(+),and e^(-)) were both presented in the Vis-CoOOH@COFs/PMS system,with O_(2)^(-) playing a dominant role in TCS degradation.Furthermore,the pathway of TCS degradation and toxicity of intermediates were explored by DFT calculation and transformation product identification.Importantly,the environmentally friendly CoOOH@COFs S-scheme heterojunction exhibited excellent stability and reusability.In conclusion,this study innovatively designed an S-scheme heterojunction in the photocatalytic-PMS activation system,providing guidance and theoretical support for efficient and eco-friendly wastewater treatment.
基金supported by the Science Fund for Distinguished Young Scholars of Hunan Province(2023JJ10060)the National Natural Science Foundation of China(22575269)Young Elite Scientists Sponsorship Program by CAST(2023QNRC001)。
文摘Recent advancements in Zn-halogen batteries have focused on enhancing the adsorptive or catalytic capability of host materials and stabilizing complex intermediates with electrolyte additives,while the halogen-ion electrolyte modifications exhibit strong potential for integrated interfacial regulation.Herein,we design an electrically insulating rigid electrolyte container to immobilize a liquid halogen-ion electrolyte for separator-free Zn-halogen batteries with customizable electron transfer.Robust hydrogen bonding of hydroxyl groups in SiO_(2)with fluorinated moieties in PVDF-hfp regulates Zn^(2+)solvation and suppresses H_(2)O activity,while multi-channels formed by microcracks and interparticle gaps not only enhance mass transfer but also buffer interfacial electric field,jointly enabling a durable Zn plating/stripping.Effective confinement of intermediates also ensures the high reversibility across single-(I^(-)/I0),double-(I^(-)/I0/I^(-)),and triple-(I^(-)/I0/I^(-),Cl-/Cl0)electron transfer mechanisms at cathode,as evidenced by the double-electron transfer systems exhibiting a low capacity decay rate of 0.02‰over 4500 cycles at 10 mA cm^(-2)and a high areal capacity of 11.9 mAh cm^(-2)at 2 mA cm^(-2).This work presents a novel“container engineering”approach to halogen-ion electrolyte design and provides fundamental insights into the relationships between redox reversibility and reaction kinetics.
基金supported by the National Key Projects for Fundamental Research and development of China(2020YFA0710202)the China Postdoctoral Science Foundation(2024M761567)Shandong Postdoctoral Science Foundation(SDCX-ZG-202400271).
文摘The synthesis of propylene carbonate(PC)from CO_(2) and propylene oxide(PO)is a typical gas-liquid biphasic system,where gas-liquid mass transfer efficiency significantly influences CO_(2) cycloaddition reactions.Here,we proposed a microchannel reaction system for the CO_(2) cycloaddition reaction catalyzed by ionic liquid within an aqueous environment.The effect of liquid flow rate,temperature and residence time on gas-liquid flow pattern,catalytic performance and mass transfer were systematically investigated.The results revealed that the PC generation rate reached 560.11 mmol·ml^(−1)·h^(−1)at a 50 cm of flow distance under reaction conditions of 105℃,2.5 MPa,QG=176 ml·min^(−1) and QL=0.3 ml·min^(−1).Variations in mass transfer rate and reaction rate at different flow distances were experimentally studied.The reaction efficiency gradually decreased with increasing flow distance,which were attributed to the reduction of mass transfer caused by decreasing bubble velocity.Optimizing bubble velocity at an appropriate position enhanced reaction efficiency by improving mass transfer,achieving a 97.7%PC yield within 2.85 min.Furthermore,a kinetic model coupling intrinsic kinetics with gas-liquid mass transfer was developed for CO_(2) cycloaddition reaction.The kinetic model was applied to predict PC reaction rates in microchannel reactors at various temperatures and liquid flow rates,achieving an average relative error of 9.6%.
文摘The radiative heat flux of the plume from reusable rockets is a critical parameter during the launch and return processes.This paper proposes a method for calculating radiative heat flux with higher accuracy than previously reported for a recoverable nine-engine liquid-propellant rocket.Based on the Radiative Transfer Equation(RTE),this study employs the discrete transfer method to solve the transient RTE problem using physical properties to describe the problem while avoiding the need to directly solve mathematical equations.The proposed method can effectively determine the radiative heat flux of the flow field and is applicable to problems involving various geometries.Calculations reveal that during the ascent phase of the rocket,the radiative heat flux at the base of the vehicle reaches its maximum in the initial stages of the lift-off,reaching a maximum of~50 kW/m^(2),which is 2.24 times the maximum value during the return phase.During the deceleration stage of re-entry into the atmosphere,the maximum radiative heat flux recorded on the sidewall of the rocket is 29.1 kW/m^(2);the maximum heat flux on the bottom surface is approximately 22.3 kW/m^(2),accounting for 76.6%of that on the rocket's sidewall.This provides a basis for the thermal protection design of the rocket's bottom and walls as well as for the thermal management of cryogenic propellant tanks.Future research will involve ground engine testing and flight experiments to further validate the proposed model.
基金partially supported by the NSF(Grant No.DMS 2324368)by the Office of the Vice Chancellor for Research and Graduate Education at the University of Wisconsin-Madison with funding from the Wisconsin Alumni Research Foundation.
文摘In this paper,we propose a systematic approach for accelerating finite element-type methods by machine learning for the numerical solution of partial differential equations(PDEs).The main idea is to use a neural network to learn the solution map of the PDEs and to do so in an element-wise fashion.This map takes input of the element geometry and the PDE’s parameters on that element,and gives output of two operators:(1)the in2out operator for inter-element communication,and(2)the in2sol operator(Green’s function)for element-wise solution recovery.A significant advantage of this approach is that,once trained,this network can be used for the numerical solution of the PDE for any domain geometry and any parameter distribution without retraining.Also,the training is significantly simpler since it is done on the element level instead on the entire domain.We call this approach element learning.This method is closely related to hybridizable discontinuous Galerkin(HDG)methods in the sense that the local solvers of HDG are replaced by machine learning approaches.Numerical tests are presented for an example PDE,the radiative transfer or radiation transport equation,in a variety of scenarios with idealized or realistic cloud fields,with smooth or sharp gradient in the cloud boundary transition.Under a fixed accuracy level of 10^(−3) in the relative L^(2) error,and polynomial degree p=6 in each element,we observe an approximately 5 to 10 times speed-up by element learning compared to a classical finite element-type method.
