Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the...Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.展开更多
KVPO_(4)F with excellent structural stability and high operating voltage has been identified as a promising cathode for potassium-ion batteries(PIBs),but limits in sluggish ion transport and severe volume change cause...KVPO_(4)F with excellent structural stability and high operating voltage has been identified as a promising cathode for potassium-ion batteries(PIBs),but limits in sluggish ion transport and severe volume change cause insufficient potassium storage capability.Here,a high-energy and low-strain KVPO_(4)F composite cathode assisted by multifunctional K_(2)C_(4)O_(4)electrode stabilizer is exquisitely designed.Systematical electrochemical investigations demonstrate that this composite cathode can deliver a remarkable energy density up to 530 Wh kg^(-1)with 142.7 mAh g^(-1)of reversible capacity at 25 mA g^(-1),outstanding rate capability of 70.6 mAh g^(-1)at 1000 mA g^(-1),and decent cycling stability.Furthermore,slight volume change(~5%)and increased interfacial stability with thin and even cathode-electrolyte interphase can be observed through in situ and ex situ characterizations,which are attributed to the synergistic effect from in situ potassium compensation and carbon deposition through self-sacrificing K_(2)C_(4)O_(4)additive.Moreover,potassium-ion full cells manifest significant improvement in energy density and cycling stability.This work demonstrates a positive impact of K_(2)C_(4)O_(4)additive on the comprehensive electrochemical enhancement,especially the activation of high-voltage plateau capacity and provides an efficient strategy to enlighten the design of other high-voltage cathodes for advanced high-energy batteries.展开更多
Pasteurella multocida(PM)has been infecting a variety of hosts for a long time,causing sustained economic losses worldwide;however,there have been limited studies on its extensive adaptability(Aktories et al.2012).Ana...Pasteurella multocida(PM)has been infecting a variety of hosts for a long time,causing sustained economic losses worldwide;however,there have been limited studies on its extensive adaptability(Aktories et al.2012).Analysis of strains data collected in our laboratory revealed that PM typically acquires foreign genes through transformation and conjugation,rather than transformation and fusion.Integrative and conjugative elements(ICEs)are a crucial mechanism that leads to abrupt changes in niche preferences and enhances environmental adaptability for bacteria,with their number far exceeding the number of plasmids and phages(Wozniak and Waldor 2010;Johnson and Grossman 2015;Botelho and Schulenburg 2021).Previous research has shown that the European bovine-sourced strain Pm36950 contains the experimentally transferable resistant ICEPmu1,which could integrate into the host chromosome or forming a circular intermediate(Michael et al.2012).Additionally,a few studies have suggested that PM strains isolated from European bovine and Asian swine might contain ICEs,but these claims lack experimental verification(Klima et al.2014;Moustafa et al.2015;Kadlec et al.2017;Peng et al.2017;Beker et al.2018;Schink et al.2022).Currently,there is no data available on ICE-carrying PM strains isolated from hosts outside of European cattle or Chinses swine.This letter presents a report on a novel ICE identified in the hypervirulent and multidrug-resistant PM HN141014 strain isolated from Chinese duck.The ICE was specifically analyzed for its resistance genes,transferable capacity and host diversity.展开更多
While a plethora of studies has been conducted to explore demotivation and its impact on mental health in second language(L2)education,scanty research focuses on demotivation in L2 speaking learning.Particularly,littl...While a plethora of studies has been conducted to explore demotivation and its impact on mental health in second language(L2)education,scanty research focuses on demotivation in L2 speaking learning.Particularly,little research explores the measures to quantify L2 speaking demotivation.The present two-phase study attempts to develop and validate an English Speaking Demotivation Scale(ESDS).To this end,an independent sample of 207 Chinese tertiary learners of English as a Foreign Language(EFL)participated in the development phase,and another group of 188 Chinese EFL learners was recruited for the validation of the scale.Exploratory Factor Analysis(EFA)and Confirmatory Factor Analysis(CFA)were employed to determine the factor structure of the scale.The EFA results revealed a six-factor solution with Teacher-related Factors in Learning Spoken English(TFLSE),Interest and Valence in Learning Spoken English(IVLSE),Self-efficacy in Learning Spoken English(SELSE),Negative Peer Influence in Learning Spoken English(NPILSE),Undesirable Environment for Learning Spoken English(UELSE),and Negative Influence of Assessment and Learning Materials in speaking class(NIALM).In the validation phase,Confirmatory Factor Analysis(CFA)was performed to validate the internal structure of the scale.The CFA results showed that the model fits the data well.Overall,the ESDS is a robust and trustworthy psychometric tool that could be utilized to examine L2 speaking demotivation.Implications for diminishing EFL learners’demotivation,lessening their aversive emotions and promoting their mental health are also discussed.展开更多
First-principles calculations were used to study the energetics and electronic structures of Ni and Sc co-doped MgH<sub>2</sub> system. The preferential positions for dopants were determined by the minimal...First-principles calculations were used to study the energetics and electronic structures of Ni and Sc co-doped MgH<sub>2</sub> system. The preferential positions for dopants were determined by the minimal total electronic energy. The results of formation enthalpy indicate that Ni and Sc co-doped MgH<sub>2</sub> system is more stable than Ni single-doped system. The hydrogen desorption enthalpies of these two hydrides are investigated. Ni and Sc co-doping can improve the dehydrogenation properties of MgH<sub>2</sub>. The lowest hydrogen desorption enthalpy of 0.30 eV appears in co-doped system, which is significantly lower than that of Ni doping. The electronic structure analysis illustrates that the hybridization of dopants with Mg and H atom together weakens the Mg-H interaction. And the Mg-H bonds are more susceptible to dissociate by Ni and Sc co-doping because of the reduced magnitude of Mg-H hybridization peaks. These behaviors effectively improve the dehydrogenation properties of Ni and Sc co-doped cases.展开更多
Purpose:Strong primary health care(PHC)systems require well‐established PHC education systems to enhance the skills of general practitioners(GPs).However,the literature on the experiences of international collaborati...Purpose:Strong primary health care(PHC)systems require well‐established PHC education systems to enhance the skills of general practitioners(GPs).However,the literature on the experiences of international collaboration in primary care education in low‐and middle‐income countries remains limited.The purpose of this study was to evaluate the implementation and perceived impact of the McGill‐Tongji Blended Education Program for Teacher Leaders in General Practice(referred to as the“Tongji Program”).Methods:In 2020–2021,the McGill Department of Family Medicine(Montreal,Canada)and Tongji University School of Medicine(TUSM,Shanghai,China)jointly implemented the Tongji Program in Shanghai,China to improve the teaching capacity of PHC teachers.We conducted an exploratory longitudinal case study with a mixed methods design for the evaluation.Quantitative(QUAN)data was collected through questionnaire surveys and qualitative(QUAL)data was collected through focus group discussions.Results:The evaluation showed that learners in Tongji Program were primarily female GPs(21/22,95%)with less than 4 years of experience in teaching(16/22,73%).This program was considered a successful learning experience by most participants(19/22,86%)with higher order learning tasks such as critical thinking and problem‐solving.They also agreed that this program helped them feel more prepared to teach(21/22,95%),and developed a positive attitude toward primary care(21/22,95%).The QUAL interview revealed that both the Tongji and McGill organizers noted that TUSM showed strong leadership in organization,education,and coordination.Both students and teachers agreed that by adapting training content into contextualized delivery formats and settings,the Tongji Program successfully overcame language and technology barriers.Conclusions:Committed partnerships and contextualization were key to the success of the Tongji Program.Future research should focus on how international primary care education programs affect learners'behavior in their practice settings,and explore barriers and facilitators to change.展开更多
The high concentration electrolytes with specific solvation structure could passivate the electrodes to prolong battery cycle life but at the expense of increased cost,which limits the wide application in commercializ...The high concentration electrolytes with specific solvation structure could passivate the electrodes to prolong battery cycle life but at the expense of increased cost,which limits the wide application in commercialization.The regular concentration(1_(M))electrolytes with suitable properties(viscosity,ionic conductivity,etc.)are cost-guaranteed,but undesired reactions would always occur and lead to battery degradation during long cycles.To promote the long-term cycle stability in a cost-effective way,this work constructs bidirectional fluorine-rich electrode/electrolyte interphase(EEI)by redistribution of solvents and electrochemical induction.The fluorinated effect with reasonable zoning planning restricts morphological disintegration,meanwhile,forms spatial confinement on cathode.In particular,the obtained cathode electrolyte interphase(CEI)gets the ample ability of Na^(+)transport,which benefits from the fluorinated organics arranged in the epitaxy and the hemi-carbonate content acting on the thickness.Thus,the electrochemical long cycling performance of F-NVPOFⅡF-CC full cells is significantly enhanced(the decay rate at 1 C per cycle is as low as 0.01%).Such a fluorine-rich EEI engineering is expected to take transitional layers against the degradation of cells and make ultra-long cycle batteries possible.展开更多
LiCoO2 surface layer is proposed and prepared through sol-gel method. The physical and electrochemical performances of pristine LiMn2O4 and LiCoO2-coated LiMn2O4 cathode materials were investigated by X-ray diffractio...LiCoO2 surface layer is proposed and prepared through sol-gel method. The physical and electrochemical performances of pristine LiMn2O4 and LiCoO2-coated LiMn2O4 cathode materials were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electrochemical measurements respectively. Comparing with the pristine LiMn2O4, the LiCoO2- coated LiMn2O4 phase significantly improved cycling stability, especially at 55°C. Additionally, the thermal safety of LiMn2O4 is greatly enhanced after being coated by LiCoO2. ICP-AES measurement, structural analysis, and impedance experiments indicate that the improved electrochemical property of LiCoO2-coated LiMn2O4 should be attributed to the alleviated dissolution loss of manganese, strengthened structural stability.展开更多
Purpose–This research aims to improve the performance of rail fastener defect inspection method for multi railways,to effectively ensure the safety of railway operation.Design/methodology/approach–Firstly,a fastener...Purpose–This research aims to improve the performance of rail fastener defect inspection method for multi railways,to effectively ensure the safety of railway operation.Design/methodology/approach–Firstly,a fastener region location method based on online learning strategy was proposed,which can locate fastener regions according to the prior knowledge of track image and template matching method.Online learning strategy is used to update the template library dynamically,so that the method not only can locate fastener regions in the track images of multi railways,but also can automatically collect and annotate fastener samples.Secondly,a fastener defect recognition method based on deep convolutional neural network was proposed.The structure of recognition network was designed according to the smaller size and the relatively single content of the fastener region.The data augmentation method based on the sample random sorting strategy is adopted to reduce the impact of the imbalance of sample size on recognition performance.Findings–Test verification of the proposed method is conducted based on the rail fastener datasets of multi railways.Specifically,fastener location module has achieved an average detection rate of 99.36%,and fastener defect recognition module has achieved an average precision of 96.82%.Originality/value–The proposed method can accurately locate fastener regions and identify fastener defect in the track images of different railways,which has high reliability and strong adaptability to multi railways.展开更多
Three-dimensional graphene-based aerogels have promising applications in oil adsorption and environmental restoration.However,current research of graphene-based aerogels is often hindered by high preparation cost,poor...Three-dimensional graphene-based aerogels have promising applications in oil adsorption and environmental restoration.However,current research of graphene-based aerogels is often hindered by high preparation cost,poor mechanical properties and low recycling efficiency.Here,superelastic graphene aerogel(SGA)was prepared through one-step freezing and twice hydrothermal reduction followed by drying under ambient pressure.The simple atmospheric drying provides a possibility for large-scale preparation of high performance graphene-based aerogels.The prepared SGA not only has the ability of highly repeatable compression rebound,but also exhibits excellent oil adsorption performance.And the overall performance of SGA is better than most of graphenebased aerogels prepared by freeze drying.After the SGA was cyclically compressed with 70%strain for 300 times,it can return to the original shape and height substantially.SGA retained about 90%of the initial adsorption capacity after 50 cycles of adsorption and compression regeneration for cyclohexane.展开更多
Rapidly increasing cryptocurrency prices have encouraged cryptocurrency miners to participate in cryptocurrency production,increasing network hashrates and electricity consumption.Growth in network hashrates has furth...Rapidly increasing cryptocurrency prices have encouraged cryptocurrency miners to participate in cryptocurrency production,increasing network hashrates and electricity consumption.Growth in network hashrates has further crowded out small cryptocurrency investors owing to the heightened costs of mining hardware and electricity.These changes prompt cryptocurrency miners to become new investors,leading to cryptocurrency price increases.The potential bidirectional relationship between cryptocurrency price and electricity consumption remains unidentified.Hence,this research thus utilizes July 312015–July 122019 data from 13 cryptocurrencies to investigate the short-and long-run causal effects between cryptocurrency transaction and electricity consumption.Particularly,we consider structural breaks induced by external shocks through stationary analysis and comovement relationships.Over the examined time period,we found that the series of cryptocurrency transaction and electricity consumption gradually returns to mean convergence after undergoing daily shocks,with prices trending together with hashrates.Transaction fluctuations exert both a temporary effect and permanent influence on electricity consumption.Therefore,owing to the computational power deployed to wherever high profit is found,transactions are vital determinants of electricity consumption.展开更多
To enhance the electrochemical performances of LiMn2O4 at elevated temperature (55°C), we proposed a sol-gel method to synthesize LiNi0.5Mn1.5O4 modified LiMn2O4. The physical and electrochemical performances of ...To enhance the electrochemical performances of LiMn2O4 at elevated temperature (55°C), we proposed a sol-gel method to synthesize LiNi0.5Mn1.5O4 modified LiMn2O4. The physical and electrochemical performances of pristine and LiNi0.5Mn1.5O4-coated LiMn2O4 cathode materials were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements, respectively. The results indicated that about 4-5 nm thick layer of LiNi0.5Mn1.5O4 was formed on the surface of the LiMn2O4 powders. The modified LiMn2O4 exhibited excellent storage performance at 55°C compared to the pristine one, which was attributed to the suppression of electrolyte decomposition and the reduction of Mn dissolution.展开更多
The M-doping (M = Zr, Hf) effects on the electronic structures and thermoelectric performance of TiCoSb were studied by first-principles calculations. The band structure analysis shows that substituting Ti with M does...The M-doping (M = Zr, Hf) effects on the electronic structures and thermoelectric performance of TiCoSb were studied by first-principles calculations. The band structure analysis shows that substituting Ti with M does not change the band structures of these systems significantly. Most of the M-doped systems have a lower band gap value than that of TiCoSb;especially Ti0.5Zr0.5CoSb has the lowest energy band gap value of 0.971 eV. Besides, the amplitudes of the density of states in the region of the valence bands for M-doped systems show a similar but slightly higher value than TiCoSb. Those suggest that these compounds could have better thermoelectric performance than TiCoSb. The phonon dispersion relations show that the larger mass of Zr/Hf with respect to Ti lowers the optical modes and induces mixing with the acoustic branches. Our calculations offer a valuable insight on how to characterize complicated crystal structures of thermoelectric materials and optimize the material composition.展开更多
Silver carp mediated biological control techniques are often advocated for controlling cyanobacteria blooms in eutrophic water,which are often enriched with arsenic(As).How-ever,the transfer and fate of As during the ...Silver carp mediated biological control techniques are often advocated for controlling cyanobacteria blooms in eutrophic water,which are often enriched with arsenic(As).How-ever,the transfer and fate of As during the biological control of cyanobacteria blooms by silver carp in As-rich eutrophic water remain unclear.Based on the simulated ecosystem experiment,the accumulation of As in silver carp and the transfer and fate of As in the water-algae-silver carp system during Microcystis aeruginosa blooms controlled by silver carp were investigated.Microcystis aeruginosa showed high tolerance to As(V).The accumulation of As in different tissues of silver carp was different,as follows:intestine>liver>gill>skin>muscle.After silver carp ingested As-rich Microcystis aeruginosa,As accumulation in the intestine,liver,gill,and skin of silver carp was enhanced under the action of digestion and skin contact.Compared with the system without algal,As accumulation in the intestine,liver,gill,and skin of silver carp increased by 1.1,3.3,3.3,and 9.6 times,respectively,after incubation for 30 days in the system with Microcystis aeruginosa,while the accumulation of As in the muscle was only slightly increased by 0.56 mg/kg.This work revealed the transfer and fate of As during algal control by silver carp,elucidated the accumulation mechanism of As in water-algae-silver carp system,enriched our understanding of As bioaccumulation and transformation in As-rich eutrophication water,and provided a scientific basis for as-sessing and predicting As migration and enrichment in water-algae-silver carp system.展开更多
The conversion of rapeseed straw into biochar not only effectively mitigates pollution from traditional straw burning but also aligns with China’s sustainable agricultural development goals. A significant quantity of...The conversion of rapeseed straw into biochar not only effectively mitigates pollution from traditional straw burning but also aligns with China’s sustainable agricultural development goals. A significant quantity of rapeseed stalks is frequently burned in fields, leading to severe air pollution characterized by black smoke and residue, resulting in a substantial waste of straw resources. To address this issue, rapeseed straw form Nanchi Village, Puzhen Town, Hanzhong City, Shaanxi Province, was utilized as a precursor and KOH was employed as an activator to produce porous activated carbon by pyrolysis. Scanning electron microscopy (SEM), elemental analyzer, infrared spectroscopy, specific surface area analysis, and other instruments were employed to characterize the porous activated carbon produced under various temperature gradients and activator concentrations. The microelement composition, structure, specific surface area, and pore size of biochar produced under varying conditions were analyzed to determine the optimal preparation parameters. Furthermore, the adsorption efficiency for tetracycline in wastewater was evaluated using a three-factor, three-level orthogonal experimental design. The results showed that the interior of the activated carbon was porous, while the exterior contained oxygenated functional groups that facilitated the adsorption of nitrogen, phosphorus, and other elements. The optimal carbonization temperature and KOH concentration for activated carbon were determined to be 400°C and 0.5, respectively. The optimal adsorption conditions were identified as pH value of 7, an initial tetracycline concentration of 30 mg/L, a biochar dosage of 0.2 g, an adsorption time of 60 min, and a removal rate of 98.53%. The factors influencing the adsorption of tetracycline onto rapeseed straw biochar were ranked as initial tetracycline concentration>adsorption reaction time>biochar dasage. The findings will provide valuable references for research on biochar performance and the treatment of tetracycline contamination in water.展开更多
To the Editor:Myopia is the most common refractive error and a major reason for visual impairment.The prevalence of myopia is increasing worldwide and is particularly high in Asian countries.It affects 80%to 90%of you...To the Editor:Myopia is the most common refractive error and a major reason for visual impairment.The prevalence of myopia is increasing worldwide and is particularly high in Asian countries.It affects 80%to 90%of young people in some parts of East and Southeast Asia.[1]High myopia,which is more than-6.00 D,increases the possibility of visual impairment due to ocular complications caused by extended axial length(AL),which include posterior uveioma,retinal detachment,choroidal new vascularization,and so on.Thus,the prevention and control of myopia is a difficult and important public health issue that has attracted great attention from the World Health Organization and the Chinese government.展开更多
Lead telluride(PbTe)is one of the reliable candidates for infrared(IR)optoelectronics with optimum band-gap as well as excellent photoelectric properties.Great interests had been paid on the growth and device applicat...Lead telluride(PbTe)is one of the reliable candidates for infrared(IR)optoelectronics with optimum band-gap as well as excellent photoelectric properties.Great interests had been paid on the growth and device applications with PbTe for the development of high-performance IR photodetectors especially those working in the near-infrared regime.Although a great deal of effort had been made to prepare PbTe nanostructures for miniaturized detectors,it is difficult to synthesize high-quality two-dimensional(2D)PbTe crystals due to its rock-salt non-layered structure.Herein,a facile strategy for controllable synthesis of ultrathin crystalline PbTe nanosheets by van der Waals epitaxy is reported.With an optimized growth temperature,which determines the morphology transit from triangular pyramid islands to regular square 2D planars,PbTe nanosheets in lateral size of tens of microns with thickness down to~7 nm are achieved.Meanwhile,ultrasensitive near-infrared detectors(NIRDs)based on the as-grown 2D PbTe nanosheets have been demonstrated with an ultrahigh responsivity exceeding 3,847 A/W at the wavelength of 1,550 nm under room temperature.Our approach demonstrates that 2D PbTe nanosheets have great latent capacity of developing high-performance miniaturized IR optoelectronic devices.展开更多
In order to provide long distance endurance and ensure the minimization of a cost function for electric vehicles,a new hybrid energy storage system for electric vehicle is designed in this paper.For the hybrid energy ...In order to provide long distance endurance and ensure the minimization of a cost function for electric vehicles,a new hybrid energy storage system for electric vehicle is designed in this paper.For the hybrid energy storage system,the paper proposes an optimal control algorithm designed using a Li-ion battery power dynamic limitation rule-based control based on the SOC of the super-capacitor.At the same time,the magnetic integration technology adding a second-order Bessel low-pass filter is introduced to DC-DC converters of electric vehicles.As a result,the size of battery is reduced,and the power quality of the hybrid energy storage system is optimized.Finally,the effectiveness of the proposed method is validated by simulation and experiment.展开更多
基金National Key R&D Program of China(2022YFB2602900)R&D Fund Project of China Academy of Railway Sciences Corporation Limited(2021YJ084)+2 种基金Project of Science and Technology R&D Program of China Railway(2016G002-K)R&D Fund Project of China Railway Major Bridge Reconnaissance&Design Institute Co.,Ltd.(2021)R&D Fund Project of China Railway Shanghai Group(2021141).
文摘Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.
基金the financial support from the National Key R&D Program of China(Grant No.2023YFE0202000)the National Natural Science Foundation of China(Grant No.52102213)+1 种基金Natural Science Foundation of Jilin Province(Grant No.20230101128JC)Double-Thousand Talents Plan of Jiangxi Province(jxsq2023102005)
文摘KVPO_(4)F with excellent structural stability and high operating voltage has been identified as a promising cathode for potassium-ion batteries(PIBs),but limits in sluggish ion transport and severe volume change cause insufficient potassium storage capability.Here,a high-energy and low-strain KVPO_(4)F composite cathode assisted by multifunctional K_(2)C_(4)O_(4)electrode stabilizer is exquisitely designed.Systematical electrochemical investigations demonstrate that this composite cathode can deliver a remarkable energy density up to 530 Wh kg^(-1)with 142.7 mAh g^(-1)of reversible capacity at 25 mA g^(-1),outstanding rate capability of 70.6 mAh g^(-1)at 1000 mA g^(-1),and decent cycling stability.Furthermore,slight volume change(~5%)and increased interfacial stability with thin and even cathode-electrolyte interphase can be observed through in situ and ex situ characterizations,which are attributed to the synergistic effect from in situ potassium compensation and carbon deposition through self-sacrificing K_(2)C_(4)O_(4)additive.Moreover,potassium-ion full cells manifest significant improvement in energy density and cycling stability.This work demonstrates a positive impact of K_(2)C_(4)O_(4)additive on the comprehensive electrochemical enhancement,especially the activation of high-voltage plateau capacity and provides an efficient strategy to enlighten the design of other high-voltage cathodes for advanced high-energy batteries.
基金supported by the earmarked fund for China Agriculture Research System(CARS-42-17)the Sichuan Veterinary Medicine and Drug Innovation Group of China Agricultural Research System(SCCXTD-2021-18)。
文摘Pasteurella multocida(PM)has been infecting a variety of hosts for a long time,causing sustained economic losses worldwide;however,there have been limited studies on its extensive adaptability(Aktories et al.2012).Analysis of strains data collected in our laboratory revealed that PM typically acquires foreign genes through transformation and conjugation,rather than transformation and fusion.Integrative and conjugative elements(ICEs)are a crucial mechanism that leads to abrupt changes in niche preferences and enhances environmental adaptability for bacteria,with their number far exceeding the number of plasmids and phages(Wozniak and Waldor 2010;Johnson and Grossman 2015;Botelho and Schulenburg 2021).Previous research has shown that the European bovine-sourced strain Pm36950 contains the experimentally transferable resistant ICEPmu1,which could integrate into the host chromosome or forming a circular intermediate(Michael et al.2012).Additionally,a few studies have suggested that PM strains isolated from European bovine and Asian swine might contain ICEs,but these claims lack experimental verification(Klima et al.2014;Moustafa et al.2015;Kadlec et al.2017;Peng et al.2017;Beker et al.2018;Schink et al.2022).Currently,there is no data available on ICE-carrying PM strains isolated from hosts outside of European cattle or Chinses swine.This letter presents a report on a novel ICE identified in the hypervirulent and multidrug-resistant PM HN141014 strain isolated from Chinese duck.The ICE was specifically analyzed for its resistance genes,transferable capacity and host diversity.
基金the Humanities and Social Sciences Project,China’s Ministry of Education(Grant Number:22YJA740016)the Key Project of Hubei Provincial Department of Education Philosophy and Social Science Research Fund(No.21ZD051)the Teaching and Research Fund of Hubei University of Technology(No.Xiao2022018).
文摘While a plethora of studies has been conducted to explore demotivation and its impact on mental health in second language(L2)education,scanty research focuses on demotivation in L2 speaking learning.Particularly,little research explores the measures to quantify L2 speaking demotivation.The present two-phase study attempts to develop and validate an English Speaking Demotivation Scale(ESDS).To this end,an independent sample of 207 Chinese tertiary learners of English as a Foreign Language(EFL)participated in the development phase,and another group of 188 Chinese EFL learners was recruited for the validation of the scale.Exploratory Factor Analysis(EFA)and Confirmatory Factor Analysis(CFA)were employed to determine the factor structure of the scale.The EFA results revealed a six-factor solution with Teacher-related Factors in Learning Spoken English(TFLSE),Interest and Valence in Learning Spoken English(IVLSE),Self-efficacy in Learning Spoken English(SELSE),Negative Peer Influence in Learning Spoken English(NPILSE),Undesirable Environment for Learning Spoken English(UELSE),and Negative Influence of Assessment and Learning Materials in speaking class(NIALM).In the validation phase,Confirmatory Factor Analysis(CFA)was performed to validate the internal structure of the scale.The CFA results showed that the model fits the data well.Overall,the ESDS is a robust and trustworthy psychometric tool that could be utilized to examine L2 speaking demotivation.Implications for diminishing EFL learners’demotivation,lessening their aversive emotions and promoting their mental health are also discussed.
文摘First-principles calculations were used to study the energetics and electronic structures of Ni and Sc co-doped MgH<sub>2</sub> system. The preferential positions for dopants were determined by the minimal total electronic energy. The results of formation enthalpy indicate that Ni and Sc co-doped MgH<sub>2</sub> system is more stable than Ni single-doped system. The hydrogen desorption enthalpies of these two hydrides are investigated. Ni and Sc co-doping can improve the dehydrogenation properties of MgH<sub>2</sub>. The lowest hydrogen desorption enthalpy of 0.30 eV appears in co-doped system, which is significantly lower than that of Ni doping. The electronic structure analysis illustrates that the hybridization of dopants with Mg and H atom together weakens the Mg-H interaction. And the Mg-H bonds are more susceptible to dissociate by Ni and Sc co-doping because of the reduced magnitude of Mg-H hybridization peaks. These behaviors effectively improve the dehydrogenation properties of Ni and Sc co-doped cases.
基金China Scholarship Council,Grant/Award Number:202000610047McGill University+4 种基金Fonds de recherche du Québec–Santé,Grant/Award Number:315852Québec Ministry of HealthCanadian Institutes for Health Research,Strategy for Patient‐Oriented Research Mentorship ChairGlobal Health Scholars ProgramFonds de recherche du Québec‐Santé,Grant/Award Number:311200。
文摘Purpose:Strong primary health care(PHC)systems require well‐established PHC education systems to enhance the skills of general practitioners(GPs).However,the literature on the experiences of international collaboration in primary care education in low‐and middle‐income countries remains limited.The purpose of this study was to evaluate the implementation and perceived impact of the McGill‐Tongji Blended Education Program for Teacher Leaders in General Practice(referred to as the“Tongji Program”).Methods:In 2020–2021,the McGill Department of Family Medicine(Montreal,Canada)and Tongji University School of Medicine(TUSM,Shanghai,China)jointly implemented the Tongji Program in Shanghai,China to improve the teaching capacity of PHC teachers.We conducted an exploratory longitudinal case study with a mixed methods design for the evaluation.Quantitative(QUAN)data was collected through questionnaire surveys and qualitative(QUAL)data was collected through focus group discussions.Results:The evaluation showed that learners in Tongji Program were primarily female GPs(21/22,95%)with less than 4 years of experience in teaching(16/22,73%).This program was considered a successful learning experience by most participants(19/22,86%)with higher order learning tasks such as critical thinking and problem‐solving.They also agreed that this program helped them feel more prepared to teach(21/22,95%),and developed a positive attitude toward primary care(21/22,95%).The QUAL interview revealed that both the Tongji and McGill organizers noted that TUSM showed strong leadership in organization,education,and coordination.Both students and teachers agreed that by adapting training content into contextualized delivery formats and settings,the Tongji Program successfully overcame language and technology barriers.Conclusions:Committed partnerships and contextualization were key to the success of the Tongji Program.Future research should focus on how international primary care education programs affect learners'behavior in their practice settings,and explore barriers and facilitators to change.
基金supported by the National Natural Science Foundation of China(No.91963118 and 52102213)Science Technology Program of Jilin Province(No.20200201066JC)the 111 Project(No.B13013).
文摘The high concentration electrolytes with specific solvation structure could passivate the electrodes to prolong battery cycle life but at the expense of increased cost,which limits the wide application in commercialization.The regular concentration(1_(M))electrolytes with suitable properties(viscosity,ionic conductivity,etc.)are cost-guaranteed,but undesired reactions would always occur and lead to battery degradation during long cycles.To promote the long-term cycle stability in a cost-effective way,this work constructs bidirectional fluorine-rich electrode/electrolyte interphase(EEI)by redistribution of solvents and electrochemical induction.The fluorinated effect with reasonable zoning planning restricts morphological disintegration,meanwhile,forms spatial confinement on cathode.In particular,the obtained cathode electrolyte interphase(CEI)gets the ample ability of Na^(+)transport,which benefits from the fluorinated organics arranged in the epitaxy and the hemi-carbonate content acting on the thickness.Thus,the electrochemical long cycling performance of F-NVPOFⅡF-CC full cells is significantly enhanced(the decay rate at 1 C per cycle is as low as 0.01%).Such a fluorine-rich EEI engineering is expected to take transitional layers against the degradation of cells and make ultra-long cycle batteries possible.
文摘LiCoO2 surface layer is proposed and prepared through sol-gel method. The physical and electrochemical performances of pristine LiMn2O4 and LiCoO2-coated LiMn2O4 cathode materials were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electrochemical measurements respectively. Comparing with the pristine LiMn2O4, the LiCoO2- coated LiMn2O4 phase significantly improved cycling stability, especially at 55°C. Additionally, the thermal safety of LiMn2O4 is greatly enhanced after being coated by LiCoO2. ICP-AES measurement, structural analysis, and impedance experiments indicate that the improved electrochemical property of LiCoO2-coated LiMn2O4 should be attributed to the alleviated dissolution loss of manganese, strengthened structural stability.
基金funded by the Key Research and Development Project of China Academy of Railway Sciences Corporation Limited(2021YJ310).
文摘Purpose–This research aims to improve the performance of rail fastener defect inspection method for multi railways,to effectively ensure the safety of railway operation.Design/methodology/approach–Firstly,a fastener region location method based on online learning strategy was proposed,which can locate fastener regions according to the prior knowledge of track image and template matching method.Online learning strategy is used to update the template library dynamically,so that the method not only can locate fastener regions in the track images of multi railways,but also can automatically collect and annotate fastener samples.Secondly,a fastener defect recognition method based on deep convolutional neural network was proposed.The structure of recognition network was designed according to the smaller size and the relatively single content of the fastener region.The data augmentation method based on the sample random sorting strategy is adopted to reduce the impact of the imbalance of sample size on recognition performance.Findings–Test verification of the proposed method is conducted based on the rail fastener datasets of multi railways.Specifically,fastener location module has achieved an average detection rate of 99.36%,and fastener defect recognition module has achieved an average precision of 96.82%.Originality/value–The proposed method can accurately locate fastener regions and identify fastener defect in the track images of different railways,which has high reliability and strong adaptability to multi railways.
基金the financial support of National Natural Science Foundation of China (22078366)
文摘Three-dimensional graphene-based aerogels have promising applications in oil adsorption and environmental restoration.However,current research of graphene-based aerogels is often hindered by high preparation cost,poor mechanical properties and low recycling efficiency.Here,superelastic graphene aerogel(SGA)was prepared through one-step freezing and twice hydrothermal reduction followed by drying under ambient pressure.The simple atmospheric drying provides a possibility for large-scale preparation of high performance graphene-based aerogels.The prepared SGA not only has the ability of highly repeatable compression rebound,but also exhibits excellent oil adsorption performance.And the overall performance of SGA is better than most of graphenebased aerogels prepared by freeze drying.After the SGA was cyclically compressed with 70%strain for 300 times,it can return to the original shape and height substantially.SGA retained about 90%of the initial adsorption capacity after 50 cycles of adsorption and compression regeneration for cyclohexane.
基金funding agencies in the public,commercial,or notfor-profit sectors.
文摘Rapidly increasing cryptocurrency prices have encouraged cryptocurrency miners to participate in cryptocurrency production,increasing network hashrates and electricity consumption.Growth in network hashrates has further crowded out small cryptocurrency investors owing to the heightened costs of mining hardware and electricity.These changes prompt cryptocurrency miners to become new investors,leading to cryptocurrency price increases.The potential bidirectional relationship between cryptocurrency price and electricity consumption remains unidentified.Hence,this research thus utilizes July 312015–July 122019 data from 13 cryptocurrencies to investigate the short-and long-run causal effects between cryptocurrency transaction and electricity consumption.Particularly,we consider structural breaks induced by external shocks through stationary analysis and comovement relationships.Over the examined time period,we found that the series of cryptocurrency transaction and electricity consumption gradually returns to mean convergence after undergoing daily shocks,with prices trending together with hashrates.Transaction fluctuations exert both a temporary effect and permanent influence on electricity consumption.Therefore,owing to the computational power deployed to wherever high profit is found,transactions are vital determinants of electricity consumption.
文摘To enhance the electrochemical performances of LiMn2O4 at elevated temperature (55°C), we proposed a sol-gel method to synthesize LiNi0.5Mn1.5O4 modified LiMn2O4. The physical and electrochemical performances of pristine and LiNi0.5Mn1.5O4-coated LiMn2O4 cathode materials were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements, respectively. The results indicated that about 4-5 nm thick layer of LiNi0.5Mn1.5O4 was formed on the surface of the LiMn2O4 powders. The modified LiMn2O4 exhibited excellent storage performance at 55°C compared to the pristine one, which was attributed to the suppression of electrolyte decomposition and the reduction of Mn dissolution.
文摘The M-doping (M = Zr, Hf) effects on the electronic structures and thermoelectric performance of TiCoSb were studied by first-principles calculations. The band structure analysis shows that substituting Ti with M does not change the band structures of these systems significantly. Most of the M-doped systems have a lower band gap value than that of TiCoSb;especially Ti0.5Zr0.5CoSb has the lowest energy band gap value of 0.971 eV. Besides, the amplitudes of the density of states in the region of the valence bands for M-doped systems show a similar but slightly higher value than TiCoSb. Those suggest that these compounds could have better thermoelectric performance than TiCoSb. The phonon dispersion relations show that the larger mass of Zr/Hf with respect to Ti lowers the optical modes and induces mixing with the acoustic branches. Our calculations offer a valuable insight on how to characterize complicated crystal structures of thermoelectric materials and optimize the material composition.
基金supported by the National Natural Science Foundation of China(Nos.41572230 and 41172219)the Grant for Innovative Research Groups of the National Natural Sci-ence Foundation of China(No.41521001)+1 种基金the Special Scien-tific Research Project of Hanzhong City-Shaanxi University of Technology Co-construction State Key Laboratory(No.SXJ-2106)the Scientific Research Foundation of State Key Laboratory of Qinba Bio-Resource and Ecological Environment(No.SXC-2105).
文摘Silver carp mediated biological control techniques are often advocated for controlling cyanobacteria blooms in eutrophic water,which are often enriched with arsenic(As).How-ever,the transfer and fate of As during the biological control of cyanobacteria blooms by silver carp in As-rich eutrophic water remain unclear.Based on the simulated ecosystem experiment,the accumulation of As in silver carp and the transfer and fate of As in the water-algae-silver carp system during Microcystis aeruginosa blooms controlled by silver carp were investigated.Microcystis aeruginosa showed high tolerance to As(V).The accumulation of As in different tissues of silver carp was different,as follows:intestine>liver>gill>skin>muscle.After silver carp ingested As-rich Microcystis aeruginosa,As accumulation in the intestine,liver,gill,and skin of silver carp was enhanced under the action of digestion and skin contact.Compared with the system without algal,As accumulation in the intestine,liver,gill,and skin of silver carp increased by 1.1,3.3,3.3,and 9.6 times,respectively,after incubation for 30 days in the system with Microcystis aeruginosa,while the accumulation of As in the muscle was only slightly increased by 0.56 mg/kg.This work revealed the transfer and fate of As during algal control by silver carp,elucidated the accumulation mechanism of As in water-algae-silver carp system,enriched our understanding of As bioaccumulation and transformation in As-rich eutrophication water,and provided a scientific basis for as-sessing and predicting As migration and enrichment in water-algae-silver carp system.
基金supported by the Key Research and Development Program of Shaanxi Province,China(Grant No.2024NC-YBXM-258,2023-YBNY-272)the Scientific Research Project of City-University Co-construction of Shaanxi Province for State Key Laboratory of Qinba Bio-Resource and Ecological Environment(Grant No.SXC-2108,SXJ-2304).
文摘The conversion of rapeseed straw into biochar not only effectively mitigates pollution from traditional straw burning but also aligns with China’s sustainable agricultural development goals. A significant quantity of rapeseed stalks is frequently burned in fields, leading to severe air pollution characterized by black smoke and residue, resulting in a substantial waste of straw resources. To address this issue, rapeseed straw form Nanchi Village, Puzhen Town, Hanzhong City, Shaanxi Province, was utilized as a precursor and KOH was employed as an activator to produce porous activated carbon by pyrolysis. Scanning electron microscopy (SEM), elemental analyzer, infrared spectroscopy, specific surface area analysis, and other instruments were employed to characterize the porous activated carbon produced under various temperature gradients and activator concentrations. The microelement composition, structure, specific surface area, and pore size of biochar produced under varying conditions were analyzed to determine the optimal preparation parameters. Furthermore, the adsorption efficiency for tetracycline in wastewater was evaluated using a three-factor, three-level orthogonal experimental design. The results showed that the interior of the activated carbon was porous, while the exterior contained oxygenated functional groups that facilitated the adsorption of nitrogen, phosphorus, and other elements. The optimal carbonization temperature and KOH concentration for activated carbon were determined to be 400°C and 0.5, respectively. The optimal adsorption conditions were identified as pH value of 7, an initial tetracycline concentration of 30 mg/L, a biochar dosage of 0.2 g, an adsorption time of 60 min, and a removal rate of 98.53%. The factors influencing the adsorption of tetracycline onto rapeseed straw biochar were ranked as initial tetracycline concentration>adsorption reaction time>biochar dasage. The findings will provide valuable references for research on biochar performance and the treatment of tetracycline contamination in water.
文摘To the Editor:Myopia is the most common refractive error and a major reason for visual impairment.The prevalence of myopia is increasing worldwide and is particularly high in Asian countries.It affects 80%to 90%of young people in some parts of East and Southeast Asia.[1]High myopia,which is more than-6.00 D,increases the possibility of visual impairment due to ocular complications caused by extended axial length(AL),which include posterior uveioma,retinal detachment,choroidal new vascularization,and so on.Thus,the prevention and control of myopia is a difficult and important public health issue that has attracted great attention from the World Health Organization and the Chinese government.
基金the National Natural Science Foundation of China(Nos.61875223,61922082 and 61927813)the Natural Science Foundation of Hainan Province(No.117111)。
文摘Lead telluride(PbTe)is one of the reliable candidates for infrared(IR)optoelectronics with optimum band-gap as well as excellent photoelectric properties.Great interests had been paid on the growth and device applications with PbTe for the development of high-performance IR photodetectors especially those working in the near-infrared regime.Although a great deal of effort had been made to prepare PbTe nanostructures for miniaturized detectors,it is difficult to synthesize high-quality two-dimensional(2D)PbTe crystals due to its rock-salt non-layered structure.Herein,a facile strategy for controllable synthesis of ultrathin crystalline PbTe nanosheets by van der Waals epitaxy is reported.With an optimized growth temperature,which determines the morphology transit from triangular pyramid islands to regular square 2D planars,PbTe nanosheets in lateral size of tens of microns with thickness down to~7 nm are achieved.Meanwhile,ultrasensitive near-infrared detectors(NIRDs)based on the as-grown 2D PbTe nanosheets have been demonstrated with an ultrahigh responsivity exceeding 3,847 A/W at the wavelength of 1,550 nm under room temperature.Our approach demonstrates that 2D PbTe nanosheets have great latent capacity of developing high-performance miniaturized IR optoelectronic devices.
基金Supported by National Natural Science Foundation of China(Grant:51307009).
文摘In order to provide long distance endurance and ensure the minimization of a cost function for electric vehicles,a new hybrid energy storage system for electric vehicle is designed in this paper.For the hybrid energy storage system,the paper proposes an optimal control algorithm designed using a Li-ion battery power dynamic limitation rule-based control based on the SOC of the super-capacitor.At the same time,the magnetic integration technology adding a second-order Bessel low-pass filter is introduced to DC-DC converters of electric vehicles.As a result,the size of battery is reduced,and the power quality of the hybrid energy storage system is optimized.Finally,the effectiveness of the proposed method is validated by simulation and experiment.
