This study develops a contact performance-driven method for skiving face gear drives using a single cutter,eliminating the traditional need for separate cutters to reduce production costs and time.First,the mathematic...This study develops a contact performance-driven method for skiving face gear drives using a single cutter,eliminating the traditional need for separate cutters to reduce production costs and time.First,the mathematical models of the tooth flanks for the face gear drives are established based on the gear skiving processes.Then,load tooth contact analysis(LTCA)model is established to calculate the contact performance data.Next,a two-stage optimization model is employed to determine the optimal parameters of the cutting edge with improved contact performances.The effectiveness of this method is validated through simulations and rolling tests.Compared with the traditional method,the proposed method can machine both the face gear and its mating pinion with a single cutter.Simulation results show that the proposed method avoids tooth surface edge contact,with the maximum tooth surface contact stress reduced by 31.7%,the contact ratio decreases by 21.5%,and the transmission error increases by 22.3%.Rolling tests verify the consistency of tooth surface contact patterns between simulations and experiments.The proposed method provides a reference for the cutting edge design of skiving cutters for face gear pairs.展开更多
The implementation of multifunctional application scenarios for mobile terminal devices has increased the energy density requirements of batteries.Increasing the charging voltage can rapidly increase the specific capa...The implementation of multifunctional application scenarios for mobile terminal devices has increased the energy density requirements of batteries.Increasing the charging voltage can rapidly increase the specific capacity of layered transition metal oxides;however,it also exacerbates the release of lattice oxygen and the contraction of the unit cell.Ternary materials are designed in a secondary particle state to meet the requirements of power battery applications.Therefore,to create ternary materials that can operate under ultrahigh voltages,attention should be given to both surface modification and particle integrity maintenance.By utilizing elemental selenium(Se)with a low melting point,easy sublimation,and multiple variable valence states,deep grain boundary modification was implemented inside the particles.The performance of the cathode material was evaluated through pouch cells,and the improvement mechanism was explored through molecular dynamics simulation calculations.Under the protection of a three-dimensional Se-rich modified layer,LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)achieved stable operation at ultrahigh voltages(4.6 V vs.Li/Li^(+));a sacrificial protection mechanism based on the chronic decomposition of the Se-rich layer was proposed to explain the efficacy of Se modification in stabilizing ternary materials.This deep grain boundary modification based on elemental Se provides a new solution for the ultrahigh-voltage operation of transition metal oxides and provides a scientific basis and technical support for solving the interface contact problem of all-solid-state batteries.展开更多
In-situ poly(1,3-dioxolane)(PDOL)-based electrolyte has received extensive attention in the research of lithium metal batteries due to its high stability to lithium anode and simple processing.However,it is still face...In-situ poly(1,3-dioxolane)(PDOL)-based electrolyte has received extensive attention in the research of lithium metal batteries due to its high stability to lithium anode and simple processing.However,it is still faced with defects such as low intrinsic ionic conductivity,a narrow electrochemical window,and poor thermal stability.A crosslinking and fluorination molecular design strategy toward PDOL is proposed to tackle the issues above.The amorphous crosslinked structure effectively improves ionic conductivity by inhibiting long-chain crystallization.Especially,the antioxidant–CF_(3)groups,stable crosslinked structure,and reduced terminal hydroxyl groups significantly enhance the electrochemical oxidation stability with a superb high-voltage window of 4.7 V.In addition,the designed electrolyte also exhibits obviously improved thermal stability with no deformation at 120°C for 5 min.Furthermore,the semi-solid NCM811||Li batteries exhibit a favourable capacity retention of 88.8%after 150 cycles at 0.5 C.Even assembled with NCM622 cathode working at 4.5 V,the semi-solid batteries can still show a satisfactory capacity retention of 85.3%after 100 cycles at 0.5 C.Also,a 0.1 Ah NCM811||Li pouch cell with active materials loading of 9 mg/cm2 demonstrates satisfactory cycling stability and working ability,which shows promising practical application prospects.展开更多
We highly commend Dr Souza et al.1for their systematic review research.The authors conducted a detailed investigation into the effects of ischemic preconditioning(IPC)on athletic performance,comparing it with placebo ...We highly commend Dr Souza et al.1for their systematic review research.The authors conducted a detailed investigation into the effects of ischemic preconditioning(IPC)on athletic performance,comparing it with placebo and no-intervention conditions.The study found that while IPC demonstrated superior effects over the no-intervention group in certain metrics(e.g.,time to exhaustion),its performance did not significantly surpass that of the placebo group.This suggests that the potential benefits of IPC may partially stem from participants’psychological expectations,or placebo effects.The study also highlighted the significant impact of placebo interventions on athletic performance,emphasizing the importance of distinguishing between placebo and no-intervention conditions in experimental designs.展开更多
We sincerely thank the authors of the commentary1 for their thoughtful analysis and constructive critique of our systematic review on ischemic preconditioning(IPC)and placebo effects in exercise capacity and athletic ...We sincerely thank the authors of the commentary1 for their thoughtful analysis and constructive critique of our systematic review on ischemic preconditioning(IPC)and placebo effects in exercise capacity and athletic performance.2Their attention to methodological details,particularly concerning the inclusion and timing of warm-up protocols across studies,is commendable and contributes meaningfully to the ongoing refinement of IPC research in sports science.展开更多
Background:Ischemic preconditioning(IPC)is purported to have beneficial effects on athletic performance,although findings are inconsistent,with some studies reporting placebo effects.The majority of studies have inves...Background:Ischemic preconditioning(IPC)is purported to have beneficial effects on athletic performance,although findings are inconsistent,with some studies reporting placebo effects.The majority of studies have investigated IPC alongside a placebo condition,but without a control condition that was devoid of experimental manipulation,thereby limiting accurate determination of the IPC effects.Therefore,the aims of this study were to assess the impact of the IPC intervention,compared to both placebo and no intervention,on exercise capacity and athletic performance.Methods:A systematic search of PubMed,Embase,SPORTDiscus,Cochrane Library,and Latin American and Caribbean Health Sciences Literature(LILACS)covering records from their inception until July 2023 was conducted.To qualify for inclusion,studies had to apply IPC as an acute intervention,comparing it with placebo and/or control conditions.Outcomes of interest were performance(force,number of repetitions,power,time to exhaustion,and time trial performance),physiological measurements(maximum oxygen consumption,and heart rate),or perceptual measurements(RPE).For each outcome measure,we conducted 3 independent meta-analyses(IPC vs.placebo,IPC vs.control,placebo vs.control)using an inverse-variance random-effects model.The between-treatment effects were quantified by the standardized mean difference(SMD),accompanied by their respective 95%confidence intervals.Additionally,we employed the Grading of Recommendations,Assessment,Development and Evaluation(GRADE)approach to assess the level of certainty in the evidence.Results:Seventy-nine studies were included in the quantitative analysis.Overall,IPC demonstrates a comparable effect to the placebo condition(using a low-pressure tourniquet),irrespective of the subjects'training level(all outcomes presenting p>0.05),except for the outcome of time to exhaustion,which exhibits a small magnitude effect(SMD=0.37;p=0.002).Additionally,the placebo exhibited effects notably greater than the control condition(outcome:number of repetitions;SMD=0.45;p=0.03),suggesting a potential influence of participants'cognitive perception on the outcomes.However,the evidence is of moderate to low certainty,regardless of the comparison or outcome.Conclusion:IPC has significant effects compared to the control intervention,but it did not surpass the placebo condition.Its administration might be influenced by the cognitive perception of the receiving subject,and the efficacy of IPC as an ergogenic strategy for enhancing exercise capacity and athletic performance remains questionable.展开更多
The purpose of this study was to explore whether gender,origin of impairment and impairment type could influence the performance of junior powerlifters athletes with physical impairment.The database was composed of 83...The purpose of this study was to explore whether gender,origin of impairment and impairment type could influence the performance of junior powerlifters athletes with physical impairment.The database was composed of 83 Para powerlifters(54 males and 29 females)who participated in the 2017 and 2019 Junior World Para Powerlifting Championships.Data related to gender,year of birth,origin of impairment and impairment type were obtained from the International Paralympic Committee website.Two-way ANOVA and Chi-square tests were used to verify the distribution and compare load performance considering different groups.For absolute and relative loads,males were stronger when compared to females(P=0.01).However,chronological age and performance load were not influenced by origin of impairment,impairment type or competition achievement(P>0.05).Our results show that the origin of the impairment and the competitive achievement do not influence the performance of junior para powerlifting athletes with physical impairment.展开更多
The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting,but its low cost-effectiveness severely restricts its large-scale ap-pli...The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting,but its low cost-effectiveness severely restricts its large-scale ap-plication.The introduction of a porous structure in bulk thermoelectric materials has been theoretically proven to effectively reduce thermal conductivity and cost.However,the electrical properties of highly porous materials are considerably suppressed due to the strong carrier scattering at the interface be-tween the matrix and pores,ultimately leading to decreased figure of merit,ZT.Here,we use an atomic layer deposition strategy to introduce some hollow glass bubbles with nano-oxide layers into commercial Bi_(0.5)Sb_(1.5)Te_(3)for preparing high-performance porous thermoelectric materials.Experimental results indi-cate that the nano-oxide layers weaken carrier scattering at the interface between pores and matrix while maintaining high-strength phonon scattering,thereby optimizing carrier/phonon transport behaviors,and effectively increasing the ZT by 23.2%(from 0.99 to 1.22 at 350 K).Besides,our strategy has excellent universality confirmed by its effectiveness in improving the ZT of Bi_(2)Te_(2.7)Se_(0.3),therefore demonstrating great potential for developing low-cost and high-performance thermoelectric materials.展开更多
Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening ...Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening weapon safety.Therefore,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals.The radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride.Through composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 GHz.The average infrared emissivity of the proposed design is 0.1063,indicating good stealth performance.The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared emissivity.Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is resolved.This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.展开更多
With the booming development of electronic information science and 5G communication technology,electromagnetic radi-ation pollution poses a huge threat and damage to humanity.Developing novel and high-performance elec...With the booming development of electronic information science and 5G communication technology,electromagnetic radi-ation pollution poses a huge threat and damage to humanity.Developing novel and high-performance electromagnetic wave(EMW)ab-sorbers is an effective method to solve the above issue and has attracted the attention of many researchers.As a typical magnetic material,ferrite plays an important role in the design of high-performance EMW absorbers,and related research focuses on diversified synthesis methods,strong absorption performance,and refined microstructure development.Herein,we focus on the synthesis of ferrites and their composites and introduce recent advances in the high-temperature solid-phase method,sol-gel method,chemical coprecipitation method,and solvent thermal method in the preparation of high-performance EMW absorbers.This review aims to help researchers understand the advantages and disadvantages of ferrite-based EMW absorbers fabricated through these methods.It also provides important guidance and reference for researchers to design high-performance EMW absorption materials based on ferrite.展开更多
Electromagnetic sandwich metastructure(ESM)consisting of different functional layers,has gained in-creasing attention in radiation prevention and radar stealth.However,the current ESM design is primar-ily based on the...Electromagnetic sandwich metastructure(ESM)consisting of different functional layers,has gained in-creasing attention in radiation prevention and radar stealth.However,the current ESM design is primar-ily based on the separation design method,ignoring electromagnetic-mechanical interactions between layers.Thus,subject to thin thickness constraint of ESM,it is a great challenge to achieve broadband microwave absorption(MA)and excellent mechanical performance simultaneously.To address this is-sue,an electromagnetic-mechanical collaborative design approach was proposed for ESM.The relations of geometric-electromagnetic and geometric-mechanical of ESM were first identified by machine learn-ing.They were then integrated with the heuristic genetic optimization algorithm to perform the highly efficient design.The designed ESM can achieve 36.4 GHz effective absorption bandwidth(EAB,RL≤-10 dB),334.3 MPa equivalent bending strength and 83 MPa compressive strength with a thickness of 9.3 mm,possessing the widest EAB and highest bending strength within the current available MA struc-tures(thickness less than 9.5 mm).The proposed approach provides an efficient tool for the design of electromagnetic-mechanical optimal ESM.展开更多
Solid-state polymer electrolytes are crucial for advancing solid-state lithium-metal batteries owing to their flexibility,excellent manufacturability,and strong interfacial compatibility.However,their widespread appli...Solid-state polymer electrolytes are crucial for advancing solid-state lithium-metal batteries owing to their flexibility,excellent manufacturability,and strong interfacial compatibility.However,their widespread applications are hindered by low ionic conductivity at room temperature and lithium dendrite growth.Herein,we report a novel solid-state composite membrane electrolyte design that combines the vertically aligned channel structure and copolymer with a radial gradient composition.Within the vertically aligned channels,the composition of poly(vinyl ethylene carbonate-co-poly(ethylene glycol)diacrylate)(P(VEC-PEGDA)varies in a gradient along the radial direction:from the center to the wall of vertically aligned channels,the proportion of vinyl ethylene carbonate(VEC)in the copolymer decreases,while the proportion of poly(ethylene glycol)diacrylate(PEGDA)increases accordingly.It can be functionally divided into a mechanical-reinforcement layer and a fast-ion-conducting layer.The resulting solid-state composite membrane electrolyte achieves a high critical current density of 1.2 mA cm^(-2)and high ionic conductivity of 2.03 mS cm^(-1)at room temperature.Employing this composite membrane electrolyte,a Li//Li symmetric cell exhibits stable cycling for over 1850 h at 0.2 m A cm^(-2)/0.2 m A h cm^(-2),and a Li//LiFePO4(LFP)battery maintains 77.3% capacity retention at 2 C after 300 cycles.Our work provides insight into the rational design of safer and more efficient solidstate batteries through electrolyte structural engineering.展开更多
The practical application of poly(ethylene oxide)(PEO)-based solid polymer electrolytes in all-solid-state lithium-metal batteries(ASSLBs)still suffers from persistent challenges associated with low ionic conductivity...The practical application of poly(ethylene oxide)(PEO)-based solid polymer electrolytes in all-solid-state lithium-metal batteries(ASSLBs)still suffers from persistent challenges associated with low ionic conductivity and poor oxidative stability.To address these issues,we introduce a novel in-situ ionization strategy using radical polymer poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl acrylate)(PTPA)to enhance ionic conductivity and achieve a high electrochemical stability window in PEO-based electrolyte.Density functional theory(DFT)calculations and molecular dynamics(MD)simulations reveal that the in-situ generation of PTPA+from PTPA within the battery,not only exceptionally decreases the low Highest Occupied Molecular Orbital(HOMO)energy level,but also exhibits a robust anchoring effect on TFSI-anions in the electrolyte,which boosts Li^(+) migration and enables dense Li deposition behavior.As a result,the PEO/10 wt%PTPA/LiTFSI electrolyte demonstrates remarkable oxidative stability up to 5 V and a high Li^(+)transference number(0.57).Li-Li symmetric cells maintain stability over 1000 h at 0.2 mA cm^(-2),and LiFePO_(4)(LFP)//Li battery also presents an enduring cyclic performance over 500 cycles with a remarkable high-capacity retention of 91.8% at 0.5C.Impressively,by coupling with a high-voltage LiCoO_(2)(LCO)cathode(cut-off voltage 4.6 V),the assembled ASSLBs reach a capacity retention of 87.1% after 500 cycles at 1C.Our study explores the mechanism of radical polymer in PEO-based electrolyte and provides a fire-new strategy for construction of high-performance and multifunctional ASSLBs.展开更多
To mitigate secondary electromagnetic pollution,there is an urgent need to develop absorption-dominant electromagnetic interference(EMI)shielding materials with low density,reduced thickness,lightweight construction,f...To mitigate secondary electromagnetic pollution,there is an urgent need to develop absorption-dominant electromagnetic interference(EMI)shielding materials with low density,reduced thickness,lightweight construction,flexibility,exceptional mechanical strength,and superior electrothermal and photothermal properties,particularly for flexible and wearable electronics.In this regard,we designed an absorption-based composite film comprising carbon nanotubes(CNT)and α-Fe_(2)O_(3),featuring a CNT layer sandwiched between twoα-Fe_(2)O_(3)layers on the upper and lower surfaces.This composite film was fabricated through an electrodeposition process followed by a thermal annealing procedure to achieve enhanced EMI shielding performance along with improved electrothermal and photothermal properties.The strategically designed sandwich structure allows the rough surface of the upper α-Fe_(2)O_(3)layer to not only improve the impedance mismatch between free space and the composite film,facilitating the penetration of incident electromagnetic(EM)waves into the film and promoting increased EM absorption rather than reflection,but also to enhance electrical conductivity,thereby improving electron mobility and density.Consequently,the average total shielding effectiveness(SE)of the CNT/Fe_(16)-300 composite demonstrates remarkable EMI shielding effectiveness(EMI SE:56.8 dB).Furthermore,the alteration in the absorption-to-reflection ratio(A/R)signifies a transition in the EMI shielding mechanism from reflection(0.69 for the pristine CNT film)to absorption(1.86 for the CNT/Fe_(16)-300)with the incremental deposition of α-Fe_(2)O_(3)nanoparticles.This work presents a feasible manufacturing approach for developing composite films with a sandwich structure that exhibits absorption-dominant EMI shielding capabilities,contributing to advancements in thermal management and multifunctional electromagnetic shielding applications.展开更多
Purpose We aimed to determine:(a)the chronic effects of interval training(IT)combined with blood flow restriction(BFR)on physiological adaptations(aerobic/anaerobic capacity and muscle responses)and performance enhanc...Purpose We aimed to determine:(a)the chronic effects of interval training(IT)combined with blood flow restriction(BFR)on physiological adaptations(aerobic/anaerobic capacity and muscle responses)and performance enhancement(endurance and sprints),and(b)the influence of participant characteristics and intervention protocols on these effects.Methods Searches were conducted in PubMed,Web of Science(Core Collection),Cochrane Library(Embase,ClinicalTrials.gov,and International Clinical Trials Registry Platform),and Chinese National Knowledge Infrastructure on April 2,with updates on October 17,2024.Pooled effects for each outcome were summarized using Hedge's g(g)through meta-analysis-based random effects models,and subgroup and regression analyses were used to explore moderators.Results A total of 24 studies with 621 participants were included.IT combined with BFR(IT+BFR)significantly improved maximal oxygen uptake(VO2_(max))(g=0.63,I^(2)=63%),mean power during the Wingate 30-s test(g=0.70,I^(2)=47%),muscle strength(g=0.88,I^(2)=64%),muscle endurance(g=0.43,I^(2)=0%),time to fatigue(g=1.26,I^(2)=86%),and maximal aerobic speed(g=0.74,I^(2)=0%)compared to IT alone.Subgroup analysis indicated that participant characteristics including training status,IT intensity,and IT modes significantly moderated VO2_(max)(subgroup differences:p<0.05).Specifically,IT+BFR showed significantly superior improvements in VO2_(max)compared to IT alone in trained individuals(g=0.76)at supra-maximal intensity(g=1.29)and moderate intensity(g=1.08)as well as in walking(g=1.64)and running(g=0.63)modes.Meta-regression analysis showed cuff width(β=0.14)was significantly associated with VO2_(max)change,identifying 8.23 cm as the minimum threshold required for significant improvement.Subgroup analyses regarding muscle strength did not reveal any significant moderators.Conclusion IT+BFR enhances physiological adaptations and optimizes aspects of endurance performance,with moderators including training status,IT protocol(intensity,mode,and type),and cuff width.This intervention addresses various IT-related challenges and provides tailored protocols and benefits for diverse populations.展开更多
With the widespread adoption of lithium-ion batteries(LIBs),safety concerns associated with flammable organic elec-trolytes have become increasingly critical.Solid-state lithium batteries(SSLBs),with enhanced safety a...With the widespread adoption of lithium-ion batteries(LIBs),safety concerns associated with flammable organic elec-trolytes have become increasingly critical.Solid-state lithium batteries(SSLBs),with enhanced safety and higher energy density potential,are regarded as a promising next-generation energy storage technology.However,the practical appli-cation of solid-state electrolytes(SSEs)remains hindered by several challenges,including low Li^(+)ion conductivity,poor interfacial compatibility with electrodes,unfavorable mechanical properties and difficulties in scalable manufacturing.This review systematically examines recent progress in SSEs,including inorganic types(oxides,sulfides,halides),organic types(polymers,plastic crystals,poly(ionic liquids)(PILs)),and the emerging class of soft solid-state electrolytes(S3Es),especially those based on“rigid-flexible synergy”composites and“Li+-desolvation”mechanism using porous frameworks.Critical assessment reveals that single-component SSEs face inherent limitations that are difficult to be fully overcome through compositional and structural modification alone.In contrast,S3Es integrate the strength of complementary components to achieve a balanced and synergic enhancement in electrochemical properties(e.g.,ionic conductivity and stability window),mechanical integrity,and processability,showing great promise as next-generation SSEs.Furthermore,the application-ori-ented challenges and emerging trends in S3E research are outlined,aiming to provide strategic insights into future develop-ment of high-performance SSEs.展开更多
[Objective] The paper aimed to study the improved effect of local beef cattle with Fleckvieh cattle and provide theoretical basic data for local cattle industry in central plain agricultural area in China. [Method] Wi...[Objective] The paper aimed to study the improved effect of local beef cattle with Fleckvieh cattle and provide theoretical basic data for local cattle industry in central plain agricultural area in China. [Method] With 500 local beef cattle as female parents and Fleckvieh cattle as male parents,hybridization improvement was conducted via artificial insemination. The growth performance,slaughter performance,milk performance and milk components of F1 and F2 hybrids were measured. [Result] The birth body weights of F2 were significantly higher than those of local beef cow,but there was no remarkable difference between F1 and local beef cow or F1 and F2. The growth rates of F1 and F2 at different stages were higher than those of local beef cattle. The slaughter performance,such as carcass weight( P < 0. 05),dressing percentage,net meat rate( P < 0. 05),marbling score of F1 and F2 were higher than those of local beef cow. Milk production performance,such as actual milk yield,305 d corrected milk yield and 4% standard milk yield of F2 were signally higher than those of F1 and local beef cattle( P< 0. 05),and F1 was markedly higher than local beef cattle( P < 0. 05). For milk composition,although milk fat percentage,milk protein rate,lactose rate and total solids( TS) of F1 and F2 were slightly lowered compared with local beef cattle at varying degrees,they were still at high levels compared with Holstein cows.[Conclusion]Fleckvieh cattle,as a male parent,can significantly improved growth performance,slaughter performance and milk performance of offsprings. It would also increases the economic efficiency of local beef cattle by higher quality and price,as well as changing production model from beef to dual purpose of beef and milk.展开更多
In the process of the development of music art, vocal music skills are an important way to express the singing content and feelings, which is beneficial for the singers to understand the specific connotation of the wo...In the process of the development of music art, vocal music skills are an important way to express the singing content and feelings, which is beneficial for the singers to understand the specific connotation of the works. From the current actual situation, there are still some problems in the process of vocal music teaching. Therefore, it is necessary to integrate various factors, especially emotional factors, psychological factors, physical factors and so on, to improve the artistic expression. This article will start with the principle of performance skills in vocal music practice and explore how to cultivate vocal music performance skills from different aspects.展开更多
Endurance athletic performance is highly related to a number of fiactors that can be altered through altitude and hypoxic training including increases in erythrocyte volume, maximal aerobic exercise capacity, capillar...Endurance athletic performance is highly related to a number of fiactors that can be altered through altitude and hypoxic training including increases in erythrocyte volume, maximal aerobic exercise capacity, capillary density, and economy. Physiological adaptations in response to acute and chronic exposure to hypoxic environments are well documented and range from short-term detrimental effects to longer-term adaptations that can improve performance at altitude and in sea-level competitions. Many altitude and hypoxic training protocols have been developed, employing various combinations of living and training at sea-level, low, moderate, and high altitudes and utilizing natural and artificial altitudes, with varying degrees of effectiveness. Several factors have been identified that are associated with individual responses to hypoxic training, and techniques for identifying those athletes most likely to benefit from hypoxic trairdng continue to be investigated. Exposure to sufficiently high altitude （2000-3000 m） for more than 12 h/day, while training at lower altitudes, for a minimum of 21 days is recommended. Timing of altitude training related to competition remains under debate, although general recommendations can be considered.展开更多
With the development of two-stage munitions(a precursor shaped charge(SC)and a following kinetic energy projectile)to attack the hard concrete targets,as well as the increasing applications of ultra-high performance c...With the development of two-stage munitions(a precursor shaped charge(SC)and a following kinetic energy projectile)to attack the hard concrete targets,as well as the increasing applications of ultra-high performance concrete(UHPC)in both civil and military protective structures,a comparative study on the impact performance of SC formed jet on UHPC target is performed experimentally and numerically at present.Firstly,a series of jet penetration/perforation test on the UHPC,45# steel and UHPC/45# steel composite targets are conducted.By assessing the penetration depth and borehole(crater and tunnel)diameter,the influences of target material and configuration as well as the standoff distance of SC on the impact performance of jet are experimentally discussed.Then,by adopting the 2 D multi-material Arbitrary Lagrange-Euler(ALE)algorithm,Fluid-Structure Interaction(FSI)method and erosion algorithm implemented in the finite element code LS-DYNA,the formation and impact performance of jet in the present test are well reproduced.Finally,based on the validated numerical algorithms,constitutive models and the corresponding parameters,the influences of target material(UHPC,NSC and 45# steel),standoff distance,target configuration(stacked and spaced)and weight efficiency on the impact performance of jet are further discussed.The derived conclusions could provide helpful references for evaluating the ballistic performance of jet and designing the protective structures.展开更多
基金Project(2024YFB3410402)supported by the National Key R&D Program of ChinaProject(52075558)supported by the National Natural Science Foundation of China+2 种基金Project(2021RC3012)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProject(2023CXQD050)supported by the Central South University Innovation-Driven Research Program,ChinaProject(CX20230255)supported by the Fundamental Research Funds for the Central Universities,China。
文摘This study develops a contact performance-driven method for skiving face gear drives using a single cutter,eliminating the traditional need for separate cutters to reduce production costs and time.First,the mathematical models of the tooth flanks for the face gear drives are established based on the gear skiving processes.Then,load tooth contact analysis(LTCA)model is established to calculate the contact performance data.Next,a two-stage optimization model is employed to determine the optimal parameters of the cutting edge with improved contact performances.The effectiveness of this method is validated through simulations and rolling tests.Compared with the traditional method,the proposed method can machine both the face gear and its mating pinion with a single cutter.Simulation results show that the proposed method avoids tooth surface edge contact,with the maximum tooth surface contact stress reduced by 31.7%,the contact ratio decreases by 21.5%,and the transmission error increases by 22.3%.Rolling tests verify the consistency of tooth surface contact patterns between simulations and experiments.The proposed method provides a reference for the cutting edge design of skiving cutters for face gear pairs.
基金supported by the National Natural Science Foundation of China (52302259)the China Postdoctoral Science Foundation (CPSF) under Grant Number 2023M741479+4 种基金the Postdoctoral Fellowship Program of CPSF under Grant Number GZB20240280the Jiangxi Provincial Natural Science Foundation (20224ACB218006)the financial support from High-level Talent Research Special Funds of Jiangxi University of Science and Technology (Grant No. 205200100670)the Jiangxi Provincial Key Laboratory of Power Energy Storage Batteries and Materials (2024SSY10011)the Major Scientific and Technological Research R&D Special Project of Jiangxi Province(20244AFI92002)
文摘The implementation of multifunctional application scenarios for mobile terminal devices has increased the energy density requirements of batteries.Increasing the charging voltage can rapidly increase the specific capacity of layered transition metal oxides;however,it also exacerbates the release of lattice oxygen and the contraction of the unit cell.Ternary materials are designed in a secondary particle state to meet the requirements of power battery applications.Therefore,to create ternary materials that can operate under ultrahigh voltages,attention should be given to both surface modification and particle integrity maintenance.By utilizing elemental selenium(Se)with a low melting point,easy sublimation,and multiple variable valence states,deep grain boundary modification was implemented inside the particles.The performance of the cathode material was evaluated through pouch cells,and the improvement mechanism was explored through molecular dynamics simulation calculations.Under the protection of a three-dimensional Se-rich modified layer,LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)achieved stable operation at ultrahigh voltages(4.6 V vs.Li/Li^(+));a sacrificial protection mechanism based on the chronic decomposition of the Se-rich layer was proposed to explain the efficacy of Se modification in stabilizing ternary materials.This deep grain boundary modification based on elemental Se provides a new solution for the ultrahigh-voltage operation of transition metal oxides and provides a scientific basis and technical support for solving the interface contact problem of all-solid-state batteries.
基金the financial support from the National Natural Science Foundation of China (No. 52072390)the National High-Level Talents Special Support Program (Leading Talent of Technological Innovation)+2 种基金the China Postdoctoral Science Foundation (No. 2023M743648)the Young Scientists Fund of the National Natural Science Foundation of China (No. 52302330)the support from the Shanghai Emperor of Cleaning Hi-Tech Co.,LTD
文摘In-situ poly(1,3-dioxolane)(PDOL)-based electrolyte has received extensive attention in the research of lithium metal batteries due to its high stability to lithium anode and simple processing.However,it is still faced with defects such as low intrinsic ionic conductivity,a narrow electrochemical window,and poor thermal stability.A crosslinking and fluorination molecular design strategy toward PDOL is proposed to tackle the issues above.The amorphous crosslinked structure effectively improves ionic conductivity by inhibiting long-chain crystallization.Especially,the antioxidant–CF_(3)groups,stable crosslinked structure,and reduced terminal hydroxyl groups significantly enhance the electrochemical oxidation stability with a superb high-voltage window of 4.7 V.In addition,the designed electrolyte also exhibits obviously improved thermal stability with no deformation at 120°C for 5 min.Furthermore,the semi-solid NCM811||Li batteries exhibit a favourable capacity retention of 88.8%after 150 cycles at 0.5 C.Even assembled with NCM622 cathode working at 4.5 V,the semi-solid batteries can still show a satisfactory capacity retention of 85.3%after 100 cycles at 0.5 C.Also,a 0.1 Ah NCM811||Li pouch cell with active materials loading of 9 mg/cm2 demonstrates satisfactory cycling stability and working ability,which shows promising practical application prospects.
文摘We highly commend Dr Souza et al.1for their systematic review research.The authors conducted a detailed investigation into the effects of ischemic preconditioning(IPC)on athletic performance,comparing it with placebo and no-intervention conditions.The study found that while IPC demonstrated superior effects over the no-intervention group in certain metrics(e.g.,time to exhaustion),its performance did not significantly surpass that of the placebo group.This suggests that the potential benefits of IPC may partially stem from participants’psychological expectations,or placebo effects.The study also highlighted the significant impact of placebo interventions on athletic performance,emphasizing the importance of distinguishing between placebo and no-intervention conditions in experimental designs.
文摘We sincerely thank the authors of the commentary1 for their thoughtful analysis and constructive critique of our systematic review on ischemic preconditioning(IPC)and placebo effects in exercise capacity and athletic performance.2Their attention to methodological details,particularly concerning the inclusion and timing of warm-up protocols across studies,is commendable and contributes meaningfully to the ongoing refinement of IPC research in sports science.
基金partially supported by the State Funding Agency of Minas Gerais,Brazil(FAPEMIG),Process No.APQ-01811-21supported by Alexander von Humboldt-Stiftung(AvH)/Coordena??o de Aperfei?oamento de Pessoal de Nível Superior(CAPES)+1 种基金National Council for Scientific and Technological Development-CNPq(Process No.308138/2022-8)supported by National Council for Scientific and Technological Development-CNPq(Process No.BPD-00905-22).
文摘Background:Ischemic preconditioning(IPC)is purported to have beneficial effects on athletic performance,although findings are inconsistent,with some studies reporting placebo effects.The majority of studies have investigated IPC alongside a placebo condition,but without a control condition that was devoid of experimental manipulation,thereby limiting accurate determination of the IPC effects.Therefore,the aims of this study were to assess the impact of the IPC intervention,compared to both placebo and no intervention,on exercise capacity and athletic performance.Methods:A systematic search of PubMed,Embase,SPORTDiscus,Cochrane Library,and Latin American and Caribbean Health Sciences Literature(LILACS)covering records from their inception until July 2023 was conducted.To qualify for inclusion,studies had to apply IPC as an acute intervention,comparing it with placebo and/or control conditions.Outcomes of interest were performance(force,number of repetitions,power,time to exhaustion,and time trial performance),physiological measurements(maximum oxygen consumption,and heart rate),or perceptual measurements(RPE).For each outcome measure,we conducted 3 independent meta-analyses(IPC vs.placebo,IPC vs.control,placebo vs.control)using an inverse-variance random-effects model.The between-treatment effects were quantified by the standardized mean difference(SMD),accompanied by their respective 95%confidence intervals.Additionally,we employed the Grading of Recommendations,Assessment,Development and Evaluation(GRADE)approach to assess the level of certainty in the evidence.Results:Seventy-nine studies were included in the quantitative analysis.Overall,IPC demonstrates a comparable effect to the placebo condition(using a low-pressure tourniquet),irrespective of the subjects'training level(all outcomes presenting p>0.05),except for the outcome of time to exhaustion,which exhibits a small magnitude effect(SMD=0.37;p=0.002).Additionally,the placebo exhibited effects notably greater than the control condition(outcome:number of repetitions;SMD=0.45;p=0.03),suggesting a potential influence of participants'cognitive perception on the outcomes.However,the evidence is of moderate to low certainty,regardless of the comparison or outcome.Conclusion:IPC has significant effects compared to the control intervention,but it did not surpass the placebo condition.Its administration might be influenced by the cognitive perception of the receiving subject,and the efficacy of IPC as an ergogenic strategy for enhancing exercise capacity and athletic performance remains questionable.
文摘The purpose of this study was to explore whether gender,origin of impairment and impairment type could influence the performance of junior powerlifters athletes with physical impairment.The database was composed of 83 Para powerlifters(54 males and 29 females)who participated in the 2017 and 2019 Junior World Para Powerlifting Championships.Data related to gender,year of birth,origin of impairment and impairment type were obtained from the International Paralympic Committee website.Two-way ANOVA and Chi-square tests were used to verify the distribution and compare load performance considering different groups.For absolute and relative loads,males were stronger when compared to females(P=0.01).However,chronological age and performance load were not influenced by origin of impairment,impairment type or competition achievement(P>0.05).Our results show that the origin of the impairment and the competitive achievement do not influence the performance of junior para powerlifting athletes with physical impairment.
基金supported by the National Natural Science Foundation of China(Nos.U21A2054,21905007)the Key Discipline of Materials Science and Engineering,Bureau of Education of Guangzhou(Grant No.202255464).
文摘The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting,but its low cost-effectiveness severely restricts its large-scale ap-plication.The introduction of a porous structure in bulk thermoelectric materials has been theoretically proven to effectively reduce thermal conductivity and cost.However,the electrical properties of highly porous materials are considerably suppressed due to the strong carrier scattering at the interface be-tween the matrix and pores,ultimately leading to decreased figure of merit,ZT.Here,we use an atomic layer deposition strategy to introduce some hollow glass bubbles with nano-oxide layers into commercial Bi_(0.5)Sb_(1.5)Te_(3)for preparing high-performance porous thermoelectric materials.Experimental results indi-cate that the nano-oxide layers weaken carrier scattering at the interface between pores and matrix while maintaining high-strength phonon scattering,thereby optimizing carrier/phonon transport behaviors,and effectively increasing the ZT by 23.2%(from 0.99 to 1.22 at 350 K).Besides,our strategy has excellent universality confirmed by its effectiveness in improving the ZT of Bi_(2)Te_(2.7)Se_(0.3),therefore demonstrating great potential for developing low-cost and high-performance thermoelectric materials.
基金supported by the National Natural Science Foundation of China(Nos.52071053,U1704253,and 52103334).
文摘Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening weapon safety.Therefore,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals.The radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride.Through composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 GHz.The average infrared emissivity of the proposed design is 0.1063,indicating good stealth performance.The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared emissivity.Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is resolved.This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.
基金supported by the National Natural Science Foundation of China(No.52377026)Taishan Scholars and Young Experts Program of Shandong Province,China(No.tsqn202103057)the Natural Science Foundation of Shandong Province,China(No.ZR2024ME046).
文摘With the booming development of electronic information science and 5G communication technology,electromagnetic radi-ation pollution poses a huge threat and damage to humanity.Developing novel and high-performance electromagnetic wave(EMW)ab-sorbers is an effective method to solve the above issue and has attracted the attention of many researchers.As a typical magnetic material,ferrite plays an important role in the design of high-performance EMW absorbers,and related research focuses on diversified synthesis methods,strong absorption performance,and refined microstructure development.Herein,we focus on the synthesis of ferrites and their composites and introduce recent advances in the high-temperature solid-phase method,sol-gel method,chemical coprecipitation method,and solvent thermal method in the preparation of high-performance EMW absorbers.This review aims to help researchers understand the advantages and disadvantages of ferrite-based EMW absorbers fabricated through these methods.It also provides important guidance and reference for researchers to design high-performance EMW absorption materials based on ferrite.
基金supported by the National Natural Sci-ence Foundation of China(Nos.52375383 and 52035011).
文摘Electromagnetic sandwich metastructure(ESM)consisting of different functional layers,has gained in-creasing attention in radiation prevention and radar stealth.However,the current ESM design is primar-ily based on the separation design method,ignoring electromagnetic-mechanical interactions between layers.Thus,subject to thin thickness constraint of ESM,it is a great challenge to achieve broadband microwave absorption(MA)and excellent mechanical performance simultaneously.To address this is-sue,an electromagnetic-mechanical collaborative design approach was proposed for ESM.The relations of geometric-electromagnetic and geometric-mechanical of ESM were first identified by machine learn-ing.They were then integrated with the heuristic genetic optimization algorithm to perform the highly efficient design.The designed ESM can achieve 36.4 GHz effective absorption bandwidth(EAB,RL≤-10 dB),334.3 MPa equivalent bending strength and 83 MPa compressive strength with a thickness of 9.3 mm,possessing the widest EAB and highest bending strength within the current available MA struc-tures(thickness less than 9.5 mm).The proposed approach provides an efficient tool for the design of electromagnetic-mechanical optimal ESM.
基金supported by the National Natural Science Foundation of China(52372099,52202328,22461142135,22479046)the Shanghai Sailing Program(22YF1455500)the Shanghai Magnolia Talent Plan Pujiang Project(24PJD128)。
文摘Solid-state polymer electrolytes are crucial for advancing solid-state lithium-metal batteries owing to their flexibility,excellent manufacturability,and strong interfacial compatibility.However,their widespread applications are hindered by low ionic conductivity at room temperature and lithium dendrite growth.Herein,we report a novel solid-state composite membrane electrolyte design that combines the vertically aligned channel structure and copolymer with a radial gradient composition.Within the vertically aligned channels,the composition of poly(vinyl ethylene carbonate-co-poly(ethylene glycol)diacrylate)(P(VEC-PEGDA)varies in a gradient along the radial direction:from the center to the wall of vertically aligned channels,the proportion of vinyl ethylene carbonate(VEC)in the copolymer decreases,while the proportion of poly(ethylene glycol)diacrylate(PEGDA)increases accordingly.It can be functionally divided into a mechanical-reinforcement layer and a fast-ion-conducting layer.The resulting solid-state composite membrane electrolyte achieves a high critical current density of 1.2 mA cm^(-2)and high ionic conductivity of 2.03 mS cm^(-1)at room temperature.Employing this composite membrane electrolyte,a Li//Li symmetric cell exhibits stable cycling for over 1850 h at 0.2 m A cm^(-2)/0.2 m A h cm^(-2),and a Li//LiFePO4(LFP)battery maintains 77.3% capacity retention at 2 C after 300 cycles.Our work provides insight into the rational design of safer and more efficient solidstate batteries through electrolyte structural engineering.
基金supported by the National Natural Science Foundation of China(51973236,51573213)Zhuhai Industry University-Research Cooperation Program(2320004002721)。
文摘The practical application of poly(ethylene oxide)(PEO)-based solid polymer electrolytes in all-solid-state lithium-metal batteries(ASSLBs)still suffers from persistent challenges associated with low ionic conductivity and poor oxidative stability.To address these issues,we introduce a novel in-situ ionization strategy using radical polymer poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl acrylate)(PTPA)to enhance ionic conductivity and achieve a high electrochemical stability window in PEO-based electrolyte.Density functional theory(DFT)calculations and molecular dynamics(MD)simulations reveal that the in-situ generation of PTPA+from PTPA within the battery,not only exceptionally decreases the low Highest Occupied Molecular Orbital(HOMO)energy level,but also exhibits a robust anchoring effect on TFSI-anions in the electrolyte,which boosts Li^(+) migration and enables dense Li deposition behavior.As a result,the PEO/10 wt%PTPA/LiTFSI electrolyte demonstrates remarkable oxidative stability up to 5 V and a high Li^(+)transference number(0.57).Li-Li symmetric cells maintain stability over 1000 h at 0.2 mA cm^(-2),and LiFePO_(4)(LFP)//Li battery also presents an enduring cyclic performance over 500 cycles with a remarkable high-capacity retention of 91.8% at 0.5C.Impressively,by coupling with a high-voltage LiCoO_(2)(LCO)cathode(cut-off voltage 4.6 V),the assembled ASSLBs reach a capacity retention of 87.1% after 500 cycles at 1C.Our study explores the mechanism of radical polymer in PEO-based electrolyte and provides a fire-new strategy for construction of high-performance and multifunctional ASSLBs.
基金financially supported by the National Natural Science Foundation of China(Nos.52222202 and 51772310)Chinese Academy of Sciences Key Research Program of Frontier Sciences(No.QYZDY-SSWJSC031)Shanghai Pilot Program for Basic Research-Chinese Academy of Science,Shanghai Branch(No.JCYJ-SHFY-2021-001).
文摘To mitigate secondary electromagnetic pollution,there is an urgent need to develop absorption-dominant electromagnetic interference(EMI)shielding materials with low density,reduced thickness,lightweight construction,flexibility,exceptional mechanical strength,and superior electrothermal and photothermal properties,particularly for flexible and wearable electronics.In this regard,we designed an absorption-based composite film comprising carbon nanotubes(CNT)and α-Fe_(2)O_(3),featuring a CNT layer sandwiched between twoα-Fe_(2)O_(3)layers on the upper and lower surfaces.This composite film was fabricated through an electrodeposition process followed by a thermal annealing procedure to achieve enhanced EMI shielding performance along with improved electrothermal and photothermal properties.The strategically designed sandwich structure allows the rough surface of the upper α-Fe_(2)O_(3)layer to not only improve the impedance mismatch between free space and the composite film,facilitating the penetration of incident electromagnetic(EM)waves into the film and promoting increased EM absorption rather than reflection,but also to enhance electrical conductivity,thereby improving electron mobility and density.Consequently,the average total shielding effectiveness(SE)of the CNT/Fe_(16)-300 composite demonstrates remarkable EMI shielding effectiveness(EMI SE:56.8 dB).Furthermore,the alteration in the absorption-to-reflection ratio(A/R)signifies a transition in the EMI shielding mechanism from reflection(0.69 for the pristine CNT film)to absorption(1.86 for the CNT/Fe_(16)-300)with the incremental deposition of α-Fe_(2)O_(3)nanoparticles.This work presents a feasible manufacturing approach for developing composite films with a sandwich structure that exhibits absorption-dominant EMI shielding capabilities,contributing to advancements in thermal management and multifunctional electromagnetic shielding applications.
文摘Purpose We aimed to determine:(a)the chronic effects of interval training(IT)combined with blood flow restriction(BFR)on physiological adaptations(aerobic/anaerobic capacity and muscle responses)and performance enhancement(endurance and sprints),and(b)the influence of participant characteristics and intervention protocols on these effects.Methods Searches were conducted in PubMed,Web of Science(Core Collection),Cochrane Library(Embase,ClinicalTrials.gov,and International Clinical Trials Registry Platform),and Chinese National Knowledge Infrastructure on April 2,with updates on October 17,2024.Pooled effects for each outcome were summarized using Hedge's g(g)through meta-analysis-based random effects models,and subgroup and regression analyses were used to explore moderators.Results A total of 24 studies with 621 participants were included.IT combined with BFR(IT+BFR)significantly improved maximal oxygen uptake(VO2_(max))(g=0.63,I^(2)=63%),mean power during the Wingate 30-s test(g=0.70,I^(2)=47%),muscle strength(g=0.88,I^(2)=64%),muscle endurance(g=0.43,I^(2)=0%),time to fatigue(g=1.26,I^(2)=86%),and maximal aerobic speed(g=0.74,I^(2)=0%)compared to IT alone.Subgroup analysis indicated that participant characteristics including training status,IT intensity,and IT modes significantly moderated VO2_(max)(subgroup differences:p<0.05).Specifically,IT+BFR showed significantly superior improvements in VO2_(max)compared to IT alone in trained individuals(g=0.76)at supra-maximal intensity(g=1.29)and moderate intensity(g=1.08)as well as in walking(g=1.64)and running(g=0.63)modes.Meta-regression analysis showed cuff width(β=0.14)was significantly associated with VO2_(max)change,identifying 8.23 cm as the minimum threshold required for significant improvement.Subgroup analyses regarding muscle strength did not reveal any significant moderators.Conclusion IT+BFR enhances physiological adaptations and optimizes aspects of endurance performance,with moderators including training status,IT protocol(intensity,mode,and type),and cuff width.This intervention addresses various IT-related challenges and provides tailored protocols and benefits for diverse populations.
基金the financial support from the National Key R&D Program of China (Grant No. 2021YFB3800300)the supports from National Key R&D Program of China (Grant No. 2022YFB3807700)+6 种基金the National Natural Science Foundation of China (Grant No. U20A20248)the supports from the National Natural Science Foundation of China (Grant Nos. W2441017, 22409103)the “Innovation Yongjiang 2035” Key R&D Program (Grant Nos. 2024Z040, 2025Z063)the National Key R&D Program of China (Grant No. 2023YFC2812700)the Natural Science Foundation of Shandong Province (Grant No. ZR2024YQ008)funding supports from the National Key R&D Program of China (Grant No. 2021YFB3800300)science and technology innovation fund for emission peak and carbon neutrality of Jiangsu province (Grant Nos. BK20220034, BK20231512)。
文摘With the widespread adoption of lithium-ion batteries(LIBs),safety concerns associated with flammable organic elec-trolytes have become increasingly critical.Solid-state lithium batteries(SSLBs),with enhanced safety and higher energy density potential,are regarded as a promising next-generation energy storage technology.However,the practical appli-cation of solid-state electrolytes(SSEs)remains hindered by several challenges,including low Li^(+)ion conductivity,poor interfacial compatibility with electrodes,unfavorable mechanical properties and difficulties in scalable manufacturing.This review systematically examines recent progress in SSEs,including inorganic types(oxides,sulfides,halides),organic types(polymers,plastic crystals,poly(ionic liquids)(PILs)),and the emerging class of soft solid-state electrolytes(S3Es),especially those based on“rigid-flexible synergy”composites and“Li+-desolvation”mechanism using porous frameworks.Critical assessment reveals that single-component SSEs face inherent limitations that are difficult to be fully overcome through compositional and structural modification alone.In contrast,S3Es integrate the strength of complementary components to achieve a balanced and synergic enhancement in electrochemical properties(e.g.,ionic conductivity and stability window),mechanical integrity,and processability,showing great promise as next-generation SSEs.Furthermore,the application-ori-ented challenges and emerging trends in S3E research are outlined,aiming to provide strategic insights into future develop-ment of high-performance SSEs.
基金Supported by National"973"Project(2011CB100802)Project of Beef Cattle Technology Innovation Team of Henan Agricultural Industry Research System(2013-14)
文摘[Objective] The paper aimed to study the improved effect of local beef cattle with Fleckvieh cattle and provide theoretical basic data for local cattle industry in central plain agricultural area in China. [Method] With 500 local beef cattle as female parents and Fleckvieh cattle as male parents,hybridization improvement was conducted via artificial insemination. The growth performance,slaughter performance,milk performance and milk components of F1 and F2 hybrids were measured. [Result] The birth body weights of F2 were significantly higher than those of local beef cow,but there was no remarkable difference between F1 and local beef cow or F1 and F2. The growth rates of F1 and F2 at different stages were higher than those of local beef cattle. The slaughter performance,such as carcass weight( P < 0. 05),dressing percentage,net meat rate( P < 0. 05),marbling score of F1 and F2 were higher than those of local beef cow. Milk production performance,such as actual milk yield,305 d corrected milk yield and 4% standard milk yield of F2 were signally higher than those of F1 and local beef cattle( P< 0. 05),and F1 was markedly higher than local beef cattle( P < 0. 05). For milk composition,although milk fat percentage,milk protein rate,lactose rate and total solids( TS) of F1 and F2 were slightly lowered compared with local beef cattle at varying degrees,they were still at high levels compared with Holstein cows.[Conclusion]Fleckvieh cattle,as a male parent,can significantly improved growth performance,slaughter performance and milk performance of offsprings. It would also increases the economic efficiency of local beef cattle by higher quality and price,as well as changing production model from beef to dual purpose of beef and milk.
文摘In the process of the development of music art, vocal music skills are an important way to express the singing content and feelings, which is beneficial for the singers to understand the specific connotation of the works. From the current actual situation, there are still some problems in the process of vocal music teaching. Therefore, it is necessary to integrate various factors, especially emotional factors, psychological factors, physical factors and so on, to improve the artistic expression. This article will start with the principle of performance skills in vocal music practice and explore how to cultivate vocal music performance skills from different aspects.
文摘Endurance athletic performance is highly related to a number of fiactors that can be altered through altitude and hypoxic training including increases in erythrocyte volume, maximal aerobic exercise capacity, capillary density, and economy. Physiological adaptations in response to acute and chronic exposure to hypoxic environments are well documented and range from short-term detrimental effects to longer-term adaptations that can improve performance at altitude and in sea-level competitions. Many altitude and hypoxic training protocols have been developed, employing various combinations of living and training at sea-level, low, moderate, and high altitudes and utilizing natural and artificial altitudes, with varying degrees of effectiveness. Several factors have been identified that are associated with individual responses to hypoxic training, and techniques for identifying those athletes most likely to benefit from hypoxic trairdng continue to be investigated. Exposure to sufficiently high altitude （2000-3000 m） for more than 12 h/day, while training at lower altitudes, for a minimum of 21 days is recommended. Timing of altitude training related to competition remains under debate, although general recommendations can be considered.
基金supported by the National Natural Science Foundation of China (51438003,51878507)
文摘With the development of two-stage munitions(a precursor shaped charge(SC)and a following kinetic energy projectile)to attack the hard concrete targets,as well as the increasing applications of ultra-high performance concrete(UHPC)in both civil and military protective structures,a comparative study on the impact performance of SC formed jet on UHPC target is performed experimentally and numerically at present.Firstly,a series of jet penetration/perforation test on the UHPC,45# steel and UHPC/45# steel composite targets are conducted.By assessing the penetration depth and borehole(crater and tunnel)diameter,the influences of target material and configuration as well as the standoff distance of SC on the impact performance of jet are experimentally discussed.Then,by adopting the 2 D multi-material Arbitrary Lagrange-Euler(ALE)algorithm,Fluid-Structure Interaction(FSI)method and erosion algorithm implemented in the finite element code LS-DYNA,the formation and impact performance of jet in the present test are well reproduced.Finally,based on the validated numerical algorithms,constitutive models and the corresponding parameters,the influences of target material(UHPC,NSC and 45# steel),standoff distance,target configuration(stacked and spaced)and weight efficiency on the impact performance of jet are further discussed.The derived conclusions could provide helpful references for evaluating the ballistic performance of jet and designing the protective structures.
