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
Theoretical calculations serve as an effective method for determining plasma temperatures within planetary atmospheres.To simulate plasma temperature,a comprehensive implementation of the energy equation is used,which...Theoretical calculations serve as an effective method for determining plasma temperatures within planetary atmospheres.To simulate plasma temperature,a comprehensive implementation of the energy equation is used,which is governed by five terms:conductivity,heating,cooling,adiabatic expansion,and advection.The derivations mentioned are strongly dependent on the collision cross section between electrons and other particles(e.g.,neutrals,ions).It is notable that the momentum transfer cross sections between electrons and neutrals have been updated in recent decades.However,the widely used momentum average collision cross sections between electrons and neutrals,derived from the momentum transfer cross sections,are collected in studies dating back nearly half a century.Therefore,it becomes imperative to revise the momentum average collision cross sections relevant to astrophysical contexts,based on the latest studies.In this study,we summarize the momentum average collision cross sections of 13 species common in planetary atmospheres:H,H_(2),He,O,CH_(4),H_(2)O,CO,N_(2),O_(2),Ar,CO_(2),N_(2)O,and NO_(2).All results are derived from the latest studies concerning the electron-neutral collision cross section and are compared with previous studies.Furthermore,we present a comparison of the derived total electron-neutral collision frequency at Mars between this study and previous studies.Prominent differences in the total electron-neutral collision frequency between this and prior studies support the significance of updating the momentum average collision cross section between electrons and neutrals in studying the planetary atmospheres.展开更多
The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising c...The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising candidates due to their built-in electric fields,ultrafast photocarrier separation,and tunable bandgaps,defect states limit their performance.Therefore,the modulation of the optoelectronic properties in such heterostructures is imperative.Surface charge transfer doping(SCTD)has emerged as a promising strategy for non-destructive modulation of electronic and optoelectronic characteristics in two-dimensional materials.In this work,we demonstrate the construction of high-performance p-i-n vertical heterojunction photodetectors through SCTD of MoTe_(2)/ReS_(2)heterostructure using p-type F_(4)-TCNQ.Systematic characterization reveals that the interfacial doping process effectively amplifies the built-in electric field,enhancing photogenerated carrier separation efficiency.Compared to the pristine heterojunction device,the doped photodetector exhibits remarkable visible to nearinfrared(635-1064 nm)performance.Particularly under 1064 nm illumination at zero bias,the device achieves a responsivity of 2.86 A/W and specific detectivity of 1.41×10^(12)Jones.Notably,the external quantum efficiency reaches an exceptional value of 334%compared to the initial 11.5%,while maintaining ultrafast response characteristics with rise/fall times of 11.6/15.6μs.This work provides new insights into interface engineering through molecular doping for developing high-performance vd W optoelectronic devices.展开更多
Chemical exchange saturation transfer magnetic resonance imaging is an advanced imaging technique that enables the detection of compounds at low concentrations with high sensitivity and spatial resolution and has been...Chemical exchange saturation transfer magnetic resonance imaging is an advanced imaging technique that enables the detection of compounds at low concentrations with high sensitivity and spatial resolution and has been extensively studied for diagnosing malignancy and stroke.In recent years,the emerging exploration of chemical exchange saturation transfer magnetic resonance imaging for detecting pathological changes in neurodegenerative diseases has opened up new possibilities for early detection and repetitive scans without ionizing radiation.This review serves as an overview of chemical exchange saturation transfer magnetic resonance imaging with detailed information on contrast mechanisms and processing methods and summarizes recent developments in both clinical and preclinical studies of chemical exchange saturation transfer magnetic resonance imaging for Alzheimer’s disease,Parkinson’s disease,multiple sclerosis,and Huntington’s disease.A comprehensive literature search was conducted using databases such as PubMed and Google Scholar,focusing on peer-reviewed articles from the past 15 years relevant to clinical and preclinical applications.The findings suggest that chemical exchange saturation transfer magnetic resonance imaging has the potential to detect molecular changes and altered metabolism,which may aid in early diagnosis and assessment of the severity of neurodegenerative diseases.Although promising results have been observed in selected clinical and preclinical trials,further validations are needed to evaluate their clinical value.When combined with other imaging modalities and advanced analytical methods,chemical exchange saturation transfer magnetic resonance imaging shows potential as an in vivo biomarker,enhancing the understanding of neuropathological mechanisms in neurodegenerative diseases.展开更多
Graphene,owing to its exceptional electronic,optical,thermal,and mechanical properties,has emerged as a highly promising material.Currently,the synthesis of large-area graphene films on metal substrates via chemical v...Graphene,owing to its exceptional electronic,optical,thermal,and mechanical properties,has emerged as a highly promising material.Currently,the synthesis of large-area graphene films on metal substrates via chemical vapor deposition remains the predominant approach for producing high-quality graphene.To realize the potential applications of graphene,it is essential to transfer graphene films to target substrates in a manner that is non-destructive,clean,and efficient,as this significantly affects the performance of graphene devices.This review examines the current methods for graphene transfer from three perspectives:non-destructive transfer,clean transfer,and high-efficiency transfer.It analyzes and compares the advancements and limitations of various transfer techniques.Finally,the review identifies the key challenges faced by current graphene transfer methods and anticipates future developmental prospects.展开更多
BACKGROUND Hepatocellular carcinoma(HCC)is a globally prevalent malignancy associated with high morbidity and mortality.Transfer RNA(tRNA)-derived small RNAs(tsRNAs),a class of small non-coding RNAs originating from t...BACKGROUND Hepatocellular carcinoma(HCC)is a globally prevalent malignancy associated with high morbidity and mortality.Transfer RNA(tRNA)-derived small RNAs(tsRNAs),a class of small non-coding RNAs originating from tRNA,have emerged as potential therapeutic targets in cancers,including HCC.However,the specific tsRNAs involved in HCC and their precise mechanisms remain largely unknown.In this study,we identify and characterize specific tsRNAs involved in the development and progression of HCC,discovering their potential as novel biomarkers for early detection and potential therapeutic targets.AIM To investigate differentially expressed tsRNAs in HCC,identify potential biomarkers,and elucidate the functions and mechanisms of tsRNAs in HCC.METHODS Differentially expressed tsRNAs in Barcelona Clinic Liver Cancer 0/A-stage HCC tissues were identified through high-throughput sequencing.Agarose gel electrophoresis,Sanger sequencing,and quantitative polymerase chain reaction were conducted to detect 5’-tRNA halve(tiRNA)-lysine(Lys)-CTT in tissues and serum samples.The diagnostic performance of 5’-tiRNA-Lys-CTT was evaluated using receiver operating characteristic analysis.HCC cell proliferation was examined using the Cell Counting Kit-8 assay,colony formation assay,and 5-ethynyl-2’-deoxyuridine staining.Additionally,the migratory capability of HCC cells was investigated using Transwell assays.RESULTS The 5’-tiRNA-Lys-CTT demonstrated excellent stability and can be easily detected.Its expression was significantly upregulated in 50 HCC tissues,110 HCC serum samples,and 5 HCC cell lines vs control groups,and the differences were all significant.This elevated expression was strongly associated with clinicopathological characteristics,particularly tumor size,Barcelona Clinic Liver Cancer stage,and cirrhosis of the liver.Receiver operating characteristic analysis revealed superior detection efficiency of 5’-tiRNA-Lys-CTT exhibits for early-stage HCC compared to established markers.Functional assays revealed that 5’-tiRNA-Lys-CTT overexpression promoted cell proliferation and migration,while its inhibition had the opposite effect.Bioinformatics predictions suggest that 5’-tiRNA-Lys-CTT may influence the development and progression of liver cancer by targeting downstream mRNA via metabolic pathways,cancer pathways,and HCC-specific pathways.CONCLUSION The 5’-tiRNA-Lys-CTT levels were higher in early HCC patients.5’-tiRNA-Lys-CTT is a promising diagnostic biomarker for early-stage HCC and may play an oncogenic role in HCC by interacting with downstream mRNA targets via specific pathways.展开更多
Transferring patients with critical illnesses from general wards to intensive care units (ICUs) is a crucial and time-sensitive process. This article presents strategies for improving the efficiency of patient transfe...Transferring patients with critical illnesses from general wards to intensive care units (ICUs) is a crucial and time-sensitive process. This article presents strategies for improving the efficiency of patient transfers, particularly in hospitals where intensive care units are located in buildings separate from general wards. Patient transfers comprise several steps: physicians issue orders, relatives are notified, equipment is prepared, and medical staff coordinate. We identified three factors that influence transfer time: preparation time for bed transfer, time required for shift handovers, and time required for between-ward patient movement. Unfamiliarity with transfer routes and long elevator wait times were factors that also influenced transfer time. The following strategies were proposed: develop a standardized material checklist, design key notes for patient transfers, and optimize transfer routes. These strategies reduced transfer times by 40% to 43%. This study demonstrates that by addressing logistical challenges and streamlining relevant procedures, hospitals can enhance safety and quality of care during patient transfers.展开更多
Herein,the liquid-solid mass trans fer characteristics in micropacked bed reactors(μPBRs)operated with immiscible liquid-liquid two-phase flow is experimentally investigated.It is found that the overall volumetric li...Herein,the liquid-solid mass trans fer characteristics in micropacked bed reactors(μPBRs)operated with immiscible liquid-liquid two-phase flow is experimentally investigated.It is found that the overall volumetric liquid-solid mass transfer coefficient(k_(s)a)increases with the total flow rate and the channelto-particle diameter ratio,while decreases with the organic-to-aqueous phase flow rate ratio.A satisfactory correlation model for calculating k_(s)a of the liquid-liquid μPBRs is developed.The new knowledge obtained would be useful in guiding the design and optimization of the liquid-liquid μPBRs.展开更多
Here we present a highly efficient protocol utilizing nickel-hydride hydrogen atom transfer catalysis for the regio-and enantioselective hydrofluorination of internal alkenes.This method efficiently assembles a wide a...Here we present a highly efficient protocol utilizing nickel-hydride hydrogen atom transfer catalysis for the regio-and enantioselective hydrofluorination of internal alkenes.This method efficiently assembles a wide array of enantioenrichedβ-fluoro amides with excellent regio-and enantioselectivity from internal unactivated alkenes.Mechanistic investigations suggest that this transformation proceeds via a NiHhydrogen atom transfer to alkene,followed by a stereoselective fluorine atom transfer process.The weak coordination effect of the tethered amide group is identified as a crucial factor governing the observed regio-and enantioselectivity.展开更多
Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance...Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance efficiency of such devices,yet the underlying mecha-nism,especially the roles of optical-ly dark triplets and spatially sepa-rated charge transfer states,is poorly understood.In the present work,we obtain the struc-tures of distinct excited states and investigate how they are involved in the charge transfer process at the Pd-octaethylporphyrin(PdOEP)and WS_(2) interface in terms of their energies and couplings.The results show that electron transfer from the triplet PdOEP formed via intersystem crossing prevails over direct electron transfer from the singlet(two orders of magnitude faster).Further analysis reveals that the relatively higher rate of triplet electron transfer compared to singlet electron transfer is mainly attributed to a smaller reorganization energy,which is dominated by the out-of-plane vibrations of the organic component.The work emphasizes the important roles of the optically dark triplets in the electron transfer of the PdOEP@WS_(2) heterostructure,and provides valuable theoretical insights for further improv-ing the optoelectronic performance of TMD-based devices.展开更多
This study utilized a sequential mediating model to examine the role of motivation to learn and transfer selfefficacy in the relationships between perceived content validity,mentoring function,continuous learning work...This study utilized a sequential mediating model to examine the role of motivation to learn and transfer selfefficacy in the relationships between perceived content validity,mentoring function,continuous learning work culture and intention to transfer learning.The sample comprized 429 final-year apprentices in Guangdong province,China(females=69.9%,Engineering&Medicine=69%,mean age=20.99,SD=1.60).The apprentices completed standardized measures of motivation to learn,transfer self-efficacy perceived content validity,mentoring function,and continuous learning work culture.Structural equation modeling was used to analyze the data.Results showed perceived content validity,mentoring function,continuous learning culture to predict intention to transfer learning.Of these factors,perceived content validity was the strongest predictor of intention to transfer learning.Of these factors,perceived content validity was the most influential predictor of intention to transfer learning.The motivation to learn and transfer self-efficacy sequentially mediated the relationship between mentoring function and intention to learning transfer to be stronger than by either alone.Although perceived content validity and continuous learning culture exhibited no significant direct effects on intention to transfer learning,they demonstrated positive indirect associations with intention to transfer via motivation to learn and transfer self-efficacy.These study findings extend the applications of the learning transfer framework to individuals undergoing apprenticeship training which also would apply to other a long-term work-based learning programs.展开更多
Current research on rail vehicle system vibrations primarily relies on numerical methods,with vibration transfer functions commonly derived through data fitting.However,the physical mechanisms underlying these vibrati...Current research on rail vehicle system vibrations primarily relies on numerical methods,with vibration transfer functions commonly derived through data fitting.However,the physical mechanisms underlying these vibrations are not well understood.To clarify the vibration transfer function and its characteristics,four basic input vectors are defined,and an analytical method is proposed.The vibration transfer functions of the vehicle system are solved,and their spatial coherence is analyzed.The results show that there are two spatial scales and four coherent modes in the vehicle system.The track irregularity wavelengths are combined with two spatial scales to alter the proportions of basic input vectors and then show the characteristics of spatial coherence.Four coherent modes are involved in wheel-rail force and primary suspension force;two coherent modes are involved in bogie vertical motion;and their dominant modes vary with the input frequency.On the other hand,the coherent modes involved in the bogie pitching motion and vehicle body motion are single and fixed over the whole range of frequency.This study presents an analytical method for the rapid solution of dynamic responses in vehicle systems and systematically analyzes the coherence behavior of vibration transfer functions with respect to tracking irregularity wavelengths.展开更多
The growing need for enhanced heat dissipation is compelling the development of more effective heat exchangers.Innovation inspired by nature bionics,four types of leaf-shaped pin fins were proposed and four combinatio...The growing need for enhanced heat dissipation is compelling the development of more effective heat exchangers.Innovation inspired by nature bionics,four types of leaf-shaped pin fins were proposed and four combinations of them were considered.The leaf-shaped design of the cooling pin fin enhances uniformity and synergy,effectively creating an optimized flow path that boosts cooling performance.Eight three-dimensional conjugate heat transfer models in staggered arrangement were developed using ANSYS-Fluent software.Aluminum6061material was used as the heat sinkmaterial and single-phase liquid water flowed through the rectangular channel where the Reynolds(R_(e))number varies from 40 to 100.Using the same boundary conditions as the software simulations,two leaf-shaped channels were printed to validate numerical models.Velocity field and temperature differences of the eight proposed leaf-shaped pin fins configurations were discussed by comparison with cylindrical pin fins.Based on the findings of this study,at a Reynolds number of 80,the Leaf B Staggered Array(LBSA)records a maximum temperature that is 0.72 K lower than that of the cylindrical pin fins arrangement.Additionally,the LBSA exhibits a reduction in the friction factor by approximately 33.3%relative to the circular pin fins array under the same R_(e).This implies that the design of LBSA has been optimized to provide better heat dissipation performance while maintaining lower energy consumption.Furthermore,the LBSA demonstrates the most favorable thermal-hydraulic performance index(TPI),which is 1.18 times higher than that of the circular pin fins arrangement at R_(e)=80.The temperature reduction and friction factor reduction of the lobed channel is more pronounced than that of the conventional cooling channel,highlighting its potential to increase heat transfer efficiency and reduce energy consumption in practical applications.展开更多
The use of nanofluids as heat transfer media represents an innovative strategy to enhance heat transfer performances.This study investigates experimentally the turbulent convective heat transfer characteristics of wat...The use of nanofluids as heat transfer media represents an innovative strategy to enhance heat transfer performances.This study investigates experimentally the turbulent convective heat transfer characteristics of waterbased nanofluids containing TiO_(2),CuO,and graphene nanoplatelet(GNP)nanoparticles as they flow through a copper tube.Both the dynamic viscosity and thermal conductivity of these nanofluids were modeled and experimentally measured across varying nanoparticle concentrations(0.01,0.02,and 0.03 vol.%)and temperatures(25℃,35℃,and 45℃).The findings indicate that the behavior of nanofluids depends on the parameter used for comparison with the base fluid.Notably,both the friction factor and heat transfer coefficient increase with higher nanoparticle volume concentrations at a constant Reynolds number.The results further reveal that the GNP/water nanofluid,with a volume concentration of 0.03%at 45℃,exhibit the highest Nusselt number,followed by the CuO/water and TiO_(2)/water nanofluids,with respective increases of 17.8%,11.09%,and 8.11%.展开更多
The excited state dynamics and critically regulated factors of reverse intersystem crossing(RISC)in through-space charge transfer(TSCT)molecules have received insufficient attention.Here,five molecules of through spac...The excited state dynamics and critically regulated factors of reverse intersystem crossing(RISC)in through-space charge transfer(TSCT)molecules have received insufficient attention.Here,five molecules of through space/bond charge transfer inducing thermally activated delayed fluorescence(TADF)are prepared,and their excited state charge transfer processes are studied by ultrafast transient absorption and theoretical calculations.DM-Z has a largerΔEST,leading to a longer lifetime of intersystem crossing(ISC),resulting in the lowest photoluminescence quantum yield(PLQY).Oppositely,ISC and RISC are demonstrated to take place with shorter lifetimes for TSCT molecules.The face-to-faceπ-πstacking interactions and electron communication enable DM-B and DM-BX to have an efficient RISC,increasing the weight coefficient of RISC from 1.7%(DM-X)to close to 50%(DM-B and DM-BX)in the solvents,which make DM-BX and DM-B to have a high PLQY.However,partial local excitation in the donor center is observed and the charge transfer is decreased for DM-G and DM-X.The triplet excited state(DM-G)or singlet excited state(DM-X)mainly undergoes inactivation through a non-radiative relaxation process,resulting in less RISC and low PLQY.This work provides theoretical hints to enhance the RISC process in the TADF materials.展开更多
The direct electrolysis of CO_(2)-captured liquid,such as bicarbonate,offers economic advantages by eliminating the CO_(2)regeneration step.However,high cell voltages remain a major barrier.Herein,we propose a new str...The direct electrolysis of CO_(2)-captured liquid,such as bicarbonate,offers economic advantages by eliminating the CO_(2)regeneration step.However,high cell voltages remain a major barrier.Herein,we propose a new strategy to build dual mass-transfer pathways for CO_(2)and ions using a carbon and anion exchange ionomer(AEI)to reduce cell voltages while achieving sufficient Faradaic efficiency(FE)for the CO_(2)reduction reaction.By optimizing the interposer materials and ratio of carbon,Ag,and AEI,sufficient FECO(57%)and low cell voltages(3.17 V)were achieved at 100 mA cm^(-2).The formation of dual masstransfer pathways in bicarbonate electrolysis was confirmed through in situ/operando visualization studies.To ensure stability,we recommend the generation of dual mass-transfer pathways using chemically and physically stable materials.Our work provides an understanding of the mass transfer in bicarbonate electrolysis and a direction for overcoming the voltage issue.展开更多
The latent heat thermal energy storage system with solid-liquid phase-change material(SLPCM-LHTES)as energy storage medium provides outstanding advantages such as system simplicity,stable temperature control,and high ...The latent heat thermal energy storage system with solid-liquid phase-change material(SLPCM-LHTES)as energy storage medium provides outstanding advantages such as system simplicity,stable temperature control,and high energy storage density,showing great potential toward addressing the energy storage problems associated with decentralized,intermittent,and unstable renewable energy sources.Notably,effective heat transfer within the SLPCM-LHTES is crucial for extending its application potential.Therefore,a comprehensive understanding of the heat transfer processes in SLPCM-LHTES from a theoretical perspective is necessary.In this review,we propose a three-stage heat transfer pathway in SLPCM-LHTES,including external heating,interfacial heat transfer,and intrinsic phase transition processes.From the perspective of this three-stage pathway,the theoretical basis of heat transfer processes and typical efficiency enhancement strategies in SLPCM-LHTES are summarized.Moreover,an overview of the typical applications of SLPCM-LHTES in various fields,such as building energy efficiency,textiles and garments,and battery thermal management,is presented.Finally,the remaining challenges and possible avenues of research in this burgeoning field will also be discussed.展开更多
Transfer-based Adversarial Attacks(TAAs)can deceive a victim model even without prior knowledge.This is achieved by leveraging the property of adversarial examples.That is,when generated from a surrogate model,they re...Transfer-based Adversarial Attacks(TAAs)can deceive a victim model even without prior knowledge.This is achieved by leveraging the property of adversarial examples.That is,when generated from a surrogate model,they retain their features if applied to other models due to their good transferability.However,adversarial examples often exhibit overfitting,as they are tailored to exploit the particular architecture and feature representation of source models.Consequently,when attempting black-box transfer attacks on different target models,their effectiveness is decreased.To solve this problem,this study proposes an approach based on a Regularized Constrained Feature Layer(RCFL).The proposed method first uses regularization constraints to attenuate the initial examples of low-frequency components.Perturbations are then added to a pre-specified layer of the source model using the back-propagation technique,in order to modify the original adversarial examples.Afterward,a regularized loss function is used to enhance the black-box transferability between different target models.The proposed method is finally tested on the ImageNet,CIFAR-100,and Stanford Car datasets with various target models,The obtained results demonstrate that it achieves a significantly higher transfer-based adversarial attack success rate compared with baseline techniques.展开更多
TheMoon is the only celestial body that human beings have visited.The design of the Earth-Moon transfer orbits is a critical issue in lunar exploration missions.In the 21st century,new lunar missions including the con...TheMoon is the only celestial body that human beings have visited.The design of the Earth-Moon transfer orbits is a critical issue in lunar exploration missions.In the 21st century,new lunar missions including the construction of the lunar space station,the permanent lunar base,and the Earth-Moon transportation network have been proposed,requiring low-cost,expansive launch windows and a fixed arrival epoch for any launch date within the launch window.The low-energy and low-thrust transfers are promising strategies to satisfy the demands.This review provides a detailed landscape of Earth-Moon transfer trajectory design processes,from the traditional patched conic to the state-of-the-art low-energy and low-thrust methods.Essential mechanisms of the various utilized dynamic models and the characteristics of the different design methods are discussed in hopes of helping readers grasp thebasic overviewof the current Earth-Moon transfer orbitdesignmethods anda deep academic background is unnecessary for the context understanding.展开更多
In scenarios such as vehicle radiation monitoring and unmanned aerial vehicle radiation detection,rapid measurements using a NaI(Tl)detector often result in low photon counts,weak characteristic peaks,and significant ...In scenarios such as vehicle radiation monitoring and unmanned aerial vehicle radiation detection,rapid measurements using a NaI(Tl)detector often result in low photon counts,weak characteristic peaks,and significant statistical fluctuations.These issues can lead to potential failures in peak-searching-based identification methods.To address the low precision associated with short-duration measurements of radionuclides,this paper proposes an identification algorithm that leverages heterogeneous spectral transfer to develop a low-count energy spectral identification model.Comparative experiments demonstrated that transferring samples from 26 classes of simulated heterogeneous gamma spectra aids in creating a reliable model for measured gamma spectra.With only 10%of target domain samples used for training,the accuracy on real low-count spectral samples was 95.56%.This performance shows a significant improvement over widely employed full-spectrum analysis methods trained on target domain samples.The proposed method also exhibits strong generalization capabilities,effectively mitigating overfitting issues in low-count energy spectral classification under short-duration measurements.展开更多
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the National Natural Science Foundation of China through Grants 42261160643,42441806,42241114,and 42304166supported by the open project funded by the Key Laboratory of Geospace Environment,Chinese Academy of Sciences,University of Science and Technology of China.
文摘Theoretical calculations serve as an effective method for determining plasma temperatures within planetary atmospheres.To simulate plasma temperature,a comprehensive implementation of the energy equation is used,which is governed by five terms:conductivity,heating,cooling,adiabatic expansion,and advection.The derivations mentioned are strongly dependent on the collision cross section between electrons and other particles(e.g.,neutrals,ions).It is notable that the momentum transfer cross sections between electrons and neutrals have been updated in recent decades.However,the widely used momentum average collision cross sections between electrons and neutrals,derived from the momentum transfer cross sections,are collected in studies dating back nearly half a century.Therefore,it becomes imperative to revise the momentum average collision cross sections relevant to astrophysical contexts,based on the latest studies.In this study,we summarize the momentum average collision cross sections of 13 species common in planetary atmospheres:H,H_(2),He,O,CH_(4),H_(2)O,CO,N_(2),O_(2),Ar,CO_(2),N_(2)O,and NO_(2).All results are derived from the latest studies concerning the electron-neutral collision cross section and are compared with previous studies.Furthermore,we present a comparison of the derived total electron-neutral collision frequency at Mars between this study and previous studies.Prominent differences in the total electron-neutral collision frequency between this and prior studies support the significance of updating the momentum average collision cross section between electrons and neutrals in studying the planetary atmospheres.
基金financial support from 2024 Domestic Visiting Scholar Program for Teachers'Professional Development in Universities(Grant No.FX2024022)National Natural Science Foundation of China(Grant No.61904043)。
文摘The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising candidates due to their built-in electric fields,ultrafast photocarrier separation,and tunable bandgaps,defect states limit their performance.Therefore,the modulation of the optoelectronic properties in such heterostructures is imperative.Surface charge transfer doping(SCTD)has emerged as a promising strategy for non-destructive modulation of electronic and optoelectronic characteristics in two-dimensional materials.In this work,we demonstrate the construction of high-performance p-i-n vertical heterojunction photodetectors through SCTD of MoTe_(2)/ReS_(2)heterostructure using p-type F_(4)-TCNQ.Systematic characterization reveals that the interfacial doping process effectively amplifies the built-in electric field,enhancing photogenerated carrier separation efficiency.Compared to the pristine heterojunction device,the doped photodetector exhibits remarkable visible to nearinfrared(635-1064 nm)performance.Particularly under 1064 nm illumination at zero bias,the device achieves a responsivity of 2.86 A/W and specific detectivity of 1.41×10^(12)Jones.Notably,the external quantum efficiency reaches an exceptional value of 334%compared to the initial 11.5%,while maintaining ultrafast response characteristics with rise/fall times of 11.6/15.6μs.This work provides new insights into interface engineering through molecular doping for developing high-performance vd W optoelectronic devices.
基金supported by The University of Hong Kong,China(109000487,109001694,204610401,and 204610519)National Natural Science Foundation of China(82402225)(to JH).
文摘Chemical exchange saturation transfer magnetic resonance imaging is an advanced imaging technique that enables the detection of compounds at low concentrations with high sensitivity and spatial resolution and has been extensively studied for diagnosing malignancy and stroke.In recent years,the emerging exploration of chemical exchange saturation transfer magnetic resonance imaging for detecting pathological changes in neurodegenerative diseases has opened up new possibilities for early detection and repetitive scans without ionizing radiation.This review serves as an overview of chemical exchange saturation transfer magnetic resonance imaging with detailed information on contrast mechanisms and processing methods and summarizes recent developments in both clinical and preclinical studies of chemical exchange saturation transfer magnetic resonance imaging for Alzheimer’s disease,Parkinson’s disease,multiple sclerosis,and Huntington’s disease.A comprehensive literature search was conducted using databases such as PubMed and Google Scholar,focusing on peer-reviewed articles from the past 15 years relevant to clinical and preclinical applications.The findings suggest that chemical exchange saturation transfer magnetic resonance imaging has the potential to detect molecular changes and altered metabolism,which may aid in early diagnosis and assessment of the severity of neurodegenerative diseases.Although promising results have been observed in selected clinical and preclinical trials,further validations are needed to evaluate their clinical value.When combined with other imaging modalities and advanced analytical methods,chemical exchange saturation transfer magnetic resonance imaging shows potential as an in vivo biomarker,enhancing the understanding of neuropathological mechanisms in neurodegenerative diseases.
基金supported by the National Key R&D Program of China(2020YFB2009002).
文摘Graphene,owing to its exceptional electronic,optical,thermal,and mechanical properties,has emerged as a highly promising material.Currently,the synthesis of large-area graphene films on metal substrates via chemical vapor deposition remains the predominant approach for producing high-quality graphene.To realize the potential applications of graphene,it is essential to transfer graphene films to target substrates in a manner that is non-destructive,clean,and efficient,as this significantly affects the performance of graphene devices.This review examines the current methods for graphene transfer from three perspectives:non-destructive transfer,clean transfer,and high-efficiency transfer.It analyzes and compares the advancements and limitations of various transfer techniques.Finally,the review identifies the key challenges faced by current graphene transfer methods and anticipates future developmental prospects.
基金Supported by the Scientific Research Project of Nantong Municipal Commission of Health and Family Planning,No.QN2023001.
文摘BACKGROUND Hepatocellular carcinoma(HCC)is a globally prevalent malignancy associated with high morbidity and mortality.Transfer RNA(tRNA)-derived small RNAs(tsRNAs),a class of small non-coding RNAs originating from tRNA,have emerged as potential therapeutic targets in cancers,including HCC.However,the specific tsRNAs involved in HCC and their precise mechanisms remain largely unknown.In this study,we identify and characterize specific tsRNAs involved in the development and progression of HCC,discovering their potential as novel biomarkers for early detection and potential therapeutic targets.AIM To investigate differentially expressed tsRNAs in HCC,identify potential biomarkers,and elucidate the functions and mechanisms of tsRNAs in HCC.METHODS Differentially expressed tsRNAs in Barcelona Clinic Liver Cancer 0/A-stage HCC tissues were identified through high-throughput sequencing.Agarose gel electrophoresis,Sanger sequencing,and quantitative polymerase chain reaction were conducted to detect 5’-tRNA halve(tiRNA)-lysine(Lys)-CTT in tissues and serum samples.The diagnostic performance of 5’-tiRNA-Lys-CTT was evaluated using receiver operating characteristic analysis.HCC cell proliferation was examined using the Cell Counting Kit-8 assay,colony formation assay,and 5-ethynyl-2’-deoxyuridine staining.Additionally,the migratory capability of HCC cells was investigated using Transwell assays.RESULTS The 5’-tiRNA-Lys-CTT demonstrated excellent stability and can be easily detected.Its expression was significantly upregulated in 50 HCC tissues,110 HCC serum samples,and 5 HCC cell lines vs control groups,and the differences were all significant.This elevated expression was strongly associated with clinicopathological characteristics,particularly tumor size,Barcelona Clinic Liver Cancer stage,and cirrhosis of the liver.Receiver operating characteristic analysis revealed superior detection efficiency of 5’-tiRNA-Lys-CTT exhibits for early-stage HCC compared to established markers.Functional assays revealed that 5’-tiRNA-Lys-CTT overexpression promoted cell proliferation and migration,while its inhibition had the opposite effect.Bioinformatics predictions suggest that 5’-tiRNA-Lys-CTT may influence the development and progression of liver cancer by targeting downstream mRNA via metabolic pathways,cancer pathways,and HCC-specific pathways.CONCLUSION The 5’-tiRNA-Lys-CTT levels were higher in early HCC patients.5’-tiRNA-Lys-CTT is a promising diagnostic biomarker for early-stage HCC and may play an oncogenic role in HCC by interacting with downstream mRNA targets via specific pathways.
文摘Transferring patients with critical illnesses from general wards to intensive care units (ICUs) is a crucial and time-sensitive process. This article presents strategies for improving the efficiency of patient transfers, particularly in hospitals where intensive care units are located in buildings separate from general wards. Patient transfers comprise several steps: physicians issue orders, relatives are notified, equipment is prepared, and medical staff coordinate. We identified three factors that influence transfer time: preparation time for bed transfer, time required for shift handovers, and time required for between-ward patient movement. Unfamiliarity with transfer routes and long elevator wait times were factors that also influenced transfer time. The following strategies were proposed: develop a standardized material checklist, design key notes for patient transfers, and optimize transfer routes. These strategies reduced transfer times by 40% to 43%. This study demonstrates that by addressing logistical challenges and streamlining relevant procedures, hospitals can enhance safety and quality of care during patient transfers.
文摘Herein,the liquid-solid mass trans fer characteristics in micropacked bed reactors(μPBRs)operated with immiscible liquid-liquid two-phase flow is experimentally investigated.It is found that the overall volumetric liquid-solid mass transfer coefficient(k_(s)a)increases with the total flow rate and the channelto-particle diameter ratio,while decreases with the organic-to-aqueous phase flow rate ratio.A satisfactory correlation model for calculating k_(s)a of the liquid-liquid μPBRs is developed.The new knowledge obtained would be useful in guiding the design and optimization of the liquid-liquid μPBRs.
基金This research was made possible as a result of a generous grant from the Fundamental Research Funds for the Central Universities(Nos.2232024Y-01,2232024A-03)the National Science Fund for Excellent Young Scholars(No.22122101).
文摘Here we present a highly efficient protocol utilizing nickel-hydride hydrogen atom transfer catalysis for the regio-and enantioselective hydrofluorination of internal alkenes.This method efficiently assembles a wide array of enantioenrichedβ-fluoro amides with excellent regio-and enantioselectivity from internal unactivated alkenes.Mechanistic investigations suggest that this transformation proceeds via a NiHhydrogen atom transfer to alkene,followed by a stereoselective fluorine atom transfer process.The weak coordination effect of the tethered amide group is identified as a crucial factor governing the observed regio-and enantioselectivity.
基金supported by the Fundamental Re-search Funds for the Central Universities(Ganglong Cui)and National Key Research and Development Pro-gram of China(No.2021YFA1500703 to Ganglong Cui)National Natural Science Foundation of China(No.22103067 to Xiao-Ying Xie)and Natural Science Foundation of Shandong Province(No.ZR2021QB105 to Xiao-Ying Xie).
文摘Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance efficiency of such devices,yet the underlying mecha-nism,especially the roles of optical-ly dark triplets and spatially sepa-rated charge transfer states,is poorly understood.In the present work,we obtain the struc-tures of distinct excited states and investigate how they are involved in the charge transfer process at the Pd-octaethylporphyrin(PdOEP)and WS_(2) interface in terms of their energies and couplings.The results show that electron transfer from the triplet PdOEP formed via intersystem crossing prevails over direct electron transfer from the singlet(two orders of magnitude faster).Further analysis reveals that the relatively higher rate of triplet electron transfer compared to singlet electron transfer is mainly attributed to a smaller reorganization energy,which is dominated by the out-of-plane vibrations of the organic component.The work emphasizes the important roles of the optically dark triplets in the electron transfer of the PdOEP@WS_(2) heterostructure,and provides valuable theoretical insights for further improv-ing the optoelectronic performance of TMD-based devices.
基金funded by Hanshan Normal University School-Level Research Initiation Program(grant numbers QD202244QD2024207)+3 种基金the Guangdong Higher Education Society’s“Fourteenth Five-Year”Plan 2024 Higher Education Research(grant number 24GYB43)the 2024 Guangdong Provincial Undergraduate Teaching Quality and Teaching Reform Engineering Project:Excellence Program for Cultivating Publicly-Funded Pre-service Teachers for Primary Education in the Context of Rural Revitalizationthe Hanshan Normal University Guangdong East Regional Education Collaborative Innovation Research Centerfunded by these sources.
文摘This study utilized a sequential mediating model to examine the role of motivation to learn and transfer selfefficacy in the relationships between perceived content validity,mentoring function,continuous learning work culture and intention to transfer learning.The sample comprized 429 final-year apprentices in Guangdong province,China(females=69.9%,Engineering&Medicine=69%,mean age=20.99,SD=1.60).The apprentices completed standardized measures of motivation to learn,transfer self-efficacy perceived content validity,mentoring function,and continuous learning work culture.Structural equation modeling was used to analyze the data.Results showed perceived content validity,mentoring function,continuous learning culture to predict intention to transfer learning.Of these factors,perceived content validity was the strongest predictor of intention to transfer learning.Of these factors,perceived content validity was the most influential predictor of intention to transfer learning.The motivation to learn and transfer self-efficacy sequentially mediated the relationship between mentoring function and intention to learning transfer to be stronger than by either alone.Although perceived content validity and continuous learning culture exhibited no significant direct effects on intention to transfer learning,they demonstrated positive indirect associations with intention to transfer via motivation to learn and transfer self-efficacy.These study findings extend the applications of the learning transfer framework to individuals undergoing apprenticeship training which also would apply to other a long-term work-based learning programs.
基金Supported by Fundamental Research Funds for the Central Universities(Grant No.2024QYBS031)Fundamental Research Funds for the Central Universities(Grant No.2022JBQY007)。
文摘Current research on rail vehicle system vibrations primarily relies on numerical methods,with vibration transfer functions commonly derived through data fitting.However,the physical mechanisms underlying these vibrations are not well understood.To clarify the vibration transfer function and its characteristics,four basic input vectors are defined,and an analytical method is proposed.The vibration transfer functions of the vehicle system are solved,and their spatial coherence is analyzed.The results show that there are two spatial scales and four coherent modes in the vehicle system.The track irregularity wavelengths are combined with two spatial scales to alter the proportions of basic input vectors and then show the characteristics of spatial coherence.Four coherent modes are involved in wheel-rail force and primary suspension force;two coherent modes are involved in bogie vertical motion;and their dominant modes vary with the input frequency.On the other hand,the coherent modes involved in the bogie pitching motion and vehicle body motion are single and fixed over the whole range of frequency.This study presents an analytical method for the rapid solution of dynamic responses in vehicle systems and systematically analyzes the coherence behavior of vibration transfer functions with respect to tracking irregularity wavelengths.
基金supported by the Shandong Provincial Natural Science Foundation,China(Grant ZR2024ME136).
文摘The growing need for enhanced heat dissipation is compelling the development of more effective heat exchangers.Innovation inspired by nature bionics,four types of leaf-shaped pin fins were proposed and four combinations of them were considered.The leaf-shaped design of the cooling pin fin enhances uniformity and synergy,effectively creating an optimized flow path that boosts cooling performance.Eight three-dimensional conjugate heat transfer models in staggered arrangement were developed using ANSYS-Fluent software.Aluminum6061material was used as the heat sinkmaterial and single-phase liquid water flowed through the rectangular channel where the Reynolds(R_(e))number varies from 40 to 100.Using the same boundary conditions as the software simulations,two leaf-shaped channels were printed to validate numerical models.Velocity field and temperature differences of the eight proposed leaf-shaped pin fins configurations were discussed by comparison with cylindrical pin fins.Based on the findings of this study,at a Reynolds number of 80,the Leaf B Staggered Array(LBSA)records a maximum temperature that is 0.72 K lower than that of the cylindrical pin fins arrangement.Additionally,the LBSA exhibits a reduction in the friction factor by approximately 33.3%relative to the circular pin fins array under the same R_(e).This implies that the design of LBSA has been optimized to provide better heat dissipation performance while maintaining lower energy consumption.Furthermore,the LBSA demonstrates the most favorable thermal-hydraulic performance index(TPI),which is 1.18 times higher than that of the circular pin fins arrangement at R_(e)=80.The temperature reduction and friction factor reduction of the lobed channel is more pronounced than that of the conventional cooling channel,highlighting its potential to increase heat transfer efficiency and reduce energy consumption in practical applications.
文摘The use of nanofluids as heat transfer media represents an innovative strategy to enhance heat transfer performances.This study investigates experimentally the turbulent convective heat transfer characteristics of waterbased nanofluids containing TiO_(2),CuO,and graphene nanoplatelet(GNP)nanoparticles as they flow through a copper tube.Both the dynamic viscosity and thermal conductivity of these nanofluids were modeled and experimentally measured across varying nanoparticle concentrations(0.01,0.02,and 0.03 vol.%)and temperatures(25℃,35℃,and 45℃).The findings indicate that the behavior of nanofluids depends on the parameter used for comparison with the base fluid.Notably,both the friction factor and heat transfer coefficient increase with higher nanoparticle volume concentrations at a constant Reynolds number.The results further reveal that the GNP/water nanofluid,with a volume concentration of 0.03%at 45℃,exhibit the highest Nusselt number,followed by the CuO/water and TiO_(2)/water nanofluids,with respective increases of 17.8%,11.09%,and 8.11%.
基金supported by the National Natural Science Foundation of China(No.22273057)the Universities Joint Laboratory of Guangdong,Hong Kong and Macao(No.2021LSYS009)+2 种基金the Natural Science Foundation of Guangdong Province(Nos.2022A1515011661,2023A1515012631)the Chemistry and Chemical Engineering Guangdong Laboratory(No.1922003)Guangdong Major Project of Basic and Applied Basic Research(No.2019B030302009)。
文摘The excited state dynamics and critically regulated factors of reverse intersystem crossing(RISC)in through-space charge transfer(TSCT)molecules have received insufficient attention.Here,five molecules of through space/bond charge transfer inducing thermally activated delayed fluorescence(TADF)are prepared,and their excited state charge transfer processes are studied by ultrafast transient absorption and theoretical calculations.DM-Z has a largerΔEST,leading to a longer lifetime of intersystem crossing(ISC),resulting in the lowest photoluminescence quantum yield(PLQY).Oppositely,ISC and RISC are demonstrated to take place with shorter lifetimes for TSCT molecules.The face-to-faceπ-πstacking interactions and electron communication enable DM-B and DM-BX to have an efficient RISC,increasing the weight coefficient of RISC from 1.7%(DM-X)to close to 50%(DM-B and DM-BX)in the solvents,which make DM-BX and DM-B to have a high PLQY.However,partial local excitation in the donor center is observed and the charge transfer is decreased for DM-G and DM-X.The triplet excited state(DM-G)or singlet excited state(DM-X)mainly undergoes inactivation through a non-radiative relaxation process,resulting in less RISC and low PLQY.This work provides theoretical hints to enhance the RISC process in the TADF materials.
基金supported by the National Research Council of Science&Technology(NST)grant funded by the Korean government(MSIT)(CAP21011-100)Additional support was provided by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(RS-2024-00431568)institutional program funding from the Korea Institute of Science and Technology。
文摘The direct electrolysis of CO_(2)-captured liquid,such as bicarbonate,offers economic advantages by eliminating the CO_(2)regeneration step.However,high cell voltages remain a major barrier.Herein,we propose a new strategy to build dual mass-transfer pathways for CO_(2)and ions using a carbon and anion exchange ionomer(AEI)to reduce cell voltages while achieving sufficient Faradaic efficiency(FE)for the CO_(2)reduction reaction.By optimizing the interposer materials and ratio of carbon,Ag,and AEI,sufficient FECO(57%)and low cell voltages(3.17 V)were achieved at 100 mA cm^(-2).The formation of dual masstransfer pathways in bicarbonate electrolysis was confirmed through in situ/operando visualization studies.To ensure stability,we recommend the generation of dual mass-transfer pathways using chemically and physically stable materials.Our work provides an understanding of the mass transfer in bicarbonate electrolysis and a direction for overcoming the voltage issue.
基金financial support was provided by the National Natural Science Foundation of China(Nos.52476146,52006008,and 52471219)the Guangdong Basic and Applied Basic Research Foundation(2023A1515140059 and 2025A1515011255)+2 种基金the Peking University Third Hospital Haidian transformation project(HDCXZHKC2023210)the National Foreign Expert Individual Human Project(Category H,No.H20240116)the State Key Laboratory of New Ceramic Materials Tsinghua University(No.KFZD202402).
文摘The latent heat thermal energy storage system with solid-liquid phase-change material(SLPCM-LHTES)as energy storage medium provides outstanding advantages such as system simplicity,stable temperature control,and high energy storage density,showing great potential toward addressing the energy storage problems associated with decentralized,intermittent,and unstable renewable energy sources.Notably,effective heat transfer within the SLPCM-LHTES is crucial for extending its application potential.Therefore,a comprehensive understanding of the heat transfer processes in SLPCM-LHTES from a theoretical perspective is necessary.In this review,we propose a three-stage heat transfer pathway in SLPCM-LHTES,including external heating,interfacial heat transfer,and intrinsic phase transition processes.From the perspective of this three-stage pathway,the theoretical basis of heat transfer processes and typical efficiency enhancement strategies in SLPCM-LHTES are summarized.Moreover,an overview of the typical applications of SLPCM-LHTES in various fields,such as building energy efficiency,textiles and garments,and battery thermal management,is presented.Finally,the remaining challenges and possible avenues of research in this burgeoning field will also be discussed.
基金supported by the Intelligent Policing Key Laboratory of Sichuan Province(No.ZNJW2022KFZD002)This work was supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant Nos.KJQN202302403,KJQN202303111).
文摘Transfer-based Adversarial Attacks(TAAs)can deceive a victim model even without prior knowledge.This is achieved by leveraging the property of adversarial examples.That is,when generated from a surrogate model,they retain their features if applied to other models due to their good transferability.However,adversarial examples often exhibit overfitting,as they are tailored to exploit the particular architecture and feature representation of source models.Consequently,when attempting black-box transfer attacks on different target models,their effectiveness is decreased.To solve this problem,this study proposes an approach based on a Regularized Constrained Feature Layer(RCFL).The proposed method first uses regularization constraints to attenuate the initial examples of low-frequency components.Perturbations are then added to a pre-specified layer of the source model using the back-propagation technique,in order to modify the original adversarial examples.Afterward,a regularized loss function is used to enhance the black-box transferability between different target models.The proposed method is finally tested on the ImageNet,CIFAR-100,and Stanford Car datasets with various target models,The obtained results demonstrate that it achieves a significantly higher transfer-based adversarial attack success rate compared with baseline techniques.
基金supported by the National Key Research and Development Program of China(No.2021YFA0717100)the National Natural Science Foundation of China(Nos.12072270 and U2013206).
文摘TheMoon is the only celestial body that human beings have visited.The design of the Earth-Moon transfer orbits is a critical issue in lunar exploration missions.In the 21st century,new lunar missions including the construction of the lunar space station,the permanent lunar base,and the Earth-Moon transportation network have been proposed,requiring low-cost,expansive launch windows and a fixed arrival epoch for any launch date within the launch window.The low-energy and low-thrust transfers are promising strategies to satisfy the demands.This review provides a detailed landscape of Earth-Moon transfer trajectory design processes,from the traditional patched conic to the state-of-the-art low-energy and low-thrust methods.Essential mechanisms of the various utilized dynamic models and the characteristics of the different design methods are discussed in hopes of helping readers grasp thebasic overviewof the current Earth-Moon transfer orbitdesignmethods anda deep academic background is unnecessary for the context understanding.
基金supported by the National Defense Fundamental Research Project(No.JCKY2022404C005)the Nuclear Energy Development Project(No.23ZG6106)+1 种基金the Sichuan Scientific and Technological Achievements Transfer and Transformation Demonstration Project(No.2023ZHCG0026)the Mianyang Applied Technology Research and Development Project(No.2021ZYZF1005)。
文摘In scenarios such as vehicle radiation monitoring and unmanned aerial vehicle radiation detection,rapid measurements using a NaI(Tl)detector often result in low photon counts,weak characteristic peaks,and significant statistical fluctuations.These issues can lead to potential failures in peak-searching-based identification methods.To address the low precision associated with short-duration measurements of radionuclides,this paper proposes an identification algorithm that leverages heterogeneous spectral transfer to develop a low-count energy spectral identification model.Comparative experiments demonstrated that transferring samples from 26 classes of simulated heterogeneous gamma spectra aids in creating a reliable model for measured gamma spectra.With only 10%of target domain samples used for training,the accuracy on real low-count spectral samples was 95.56%.This performance shows a significant improvement over widely employed full-spectrum analysis methods trained on target domain samples.The proposed method also exhibits strong generalization capabilities,effectively mitigating overfitting issues in low-count energy spectral classification under short-duration measurements.
