We describe the case of a 77-year-old female who underwent dual-chamber permanent pacemaker implantation using two active screw-in leads for complete atrioventricular block. The two active screw-in leads perforated th...We describe the case of a 77-year-old female who underwent dual-chamber permanent pacemaker implantation using two active screw-in leads for complete atrioventricular block. The two active screw-in leads perforated the atrial and ventricular walls causing cardiac tamponade and a left hemothorax associated with ventricular perforation. An emergency sternotomy was performed to facilitate drainage and hemostasis. Although hemothorax due to pacing lead perforation is very rare, such a possibility should always be considered.展开更多
China’s shipbuilding industry maintained the world’s largest market share in terms of three major indicators for the 16th consecutive year in 2025,according to data released by the Ministry of Industry and Informati...China’s shipbuilding industry maintained the world’s largest market share in terms of three major indicators for the 16th consecutive year in 2025,according to data released by the Ministry of Industry and Information Technology on 1 February.展开更多
For hypersonic air-breathing vehicles,the V-shaped leading edges(VSLEs)of supersonic combustion ramjet(scramjet)inlets experience complex shock interactions and intense aerodynamic loads.This paper provides a comprehe...For hypersonic air-breathing vehicles,the V-shaped leading edges(VSLEs)of supersonic combustion ramjet(scramjet)inlets experience complex shock interactions and intense aerodynamic loads.This paper provides a comprehensive review of flow characteristics at the crotch of VSLEs,with particular focus on the transition of shock interaction types and the variation of wall heat flux under different freestream Mach numbers and geometric configurations.The mechanisms governing shock transition,unsteady oscillations,hysteresis,and three-dimensional effects in VSLE flows are first examined.Subsequently,thermal protection strategies aimed at mitigating extreme heating loads are reviewed,emphasizing their relevance to practical engineering applications.Special attention is given to recent studies addressing thermochemical nonequilibrium effects on VSLE shock interactions,and the limitations of current research are critically assessed.Finally,perspectives for future investigations into hypersonic VSLE shock interactions are outlined,highlighting opportunities for advancing design and thermal management strategies.展开更多
Although lead(Pb)-based perovskite solar cells(PSCs)have garnered intense attention for their remarkable photovoltaic conversion efficiency,their commercial process is urgently in need of an effective damage-evaluatio...Although lead(Pb)-based perovskite solar cells(PSCs)have garnered intense attention for their remarkable photovoltaic conversion efficiency,their commercial process is urgently in need of an effective damage-evaluation system for the early diagnosis of faulty PSCs.The main cause of microdamage in perovskite films is the outflow of Pb,which significantly impacts device performance.However,no reliable correlation has been established between classical damage detection techniques and Pb detection,resulting in limited detection sensitivity.Here,we report an in situ visual microdamage evaluation method of PSCs by coating the device surface with a silica gel encapsulation layer containing porphyrin molecules.This detection technology enables high selectivity and sensitivity based on the strong complexation between the porphyrin ring and trace Pb outflow from degraded PSCs.By establishing the linear relationship between the fluorescence intensity and Pb concentration in PSCs,trace Pb outflow is pinpointed and quantified with a low detection limit of 0.65μg cm^(-2).An applet is developed for the insitu visual fluorescence detection method to facilitate the continuous real-time monitoring of series-type PSCs,thereby enabling the prompt identification and replacement of damaged PSCs and ensuring the swift restoration of high efficiency.展开更多
This study investigates the potential of Prosopis cineraria Leaves Powder(PCLP)as a biosorbent for removing lead(Pb)and zinc(Zn)from aqueous solutions,optimizing the process using Response Surface Methodology(RSM).Pro...This study investigates the potential of Prosopis cineraria Leaves Powder(PCLP)as a biosorbent for removing lead(Pb)and zinc(Zn)from aqueous solutions,optimizing the process using Response Surface Methodology(RSM).Prosopis cineraria,commonly known as Khejri,is a drought-resistant tree with significant promise in environmental applications.The research employed a Central Composite Design(CCD)to examine the independent and combined effects of key process variables,including initial metal ion concentration,contact time,pH,and PCLP dosage.RSM was used to develop mathematical models that explain the relationship between these factors and the efficiency of metal removal,allowing the determination of optimal operating conditions.The experimental results indicated that the Langmuir isotherm model was the most appropriate for describing the biosorption of both metals,suggesting favorable adsorption characteristics.Additionally,the D-R isotherm confirmed that chemisorption was the primary mechanism involved in the biosorption process.For lead removal,the optimal conditions were found to be 312.23 K temperature,pH 4.72,58.5 mg L-1 initial concentration,and 0.27 g biosorbent dosage,achieving an 83.77%removal efficiency.For zinc,the optimal conditions were 312.4 K,pH 5.86,53.07 mg L-1 initial concentration,and the same biosorbent dosage,resulting in a 75.86%removal efficiency.These findings highlight PCLP’s potential as an effective,eco-friendly biosorbent for sustainable heavy metal removal in water treatment.展开更多
Lead chalcohalides(PbYX,X=Cl,Br,I;Y=S,Se)is an extension of the classic Pb chalcogenides(PbY).Constructing the heterogeneous integration with PbYX and PbY material systems makes it possible to achieve significantly im...Lead chalcohalides(PbYX,X=Cl,Br,I;Y=S,Se)is an extension of the classic Pb chalcogenides(PbY).Constructing the heterogeneous integration with PbYX and PbY material systems makes it possible to achieve significantly improved optoelectronic performance.In this work,we studied the effect of introducing halogen precursors on the structure of classical PbS nanocrystals(NCs)during the synthesis process and realized the preparation of PbS/Pb_(3)S_(2)X_(2) core/shell structure for the first time.The core/shell structure can effectively improve their optical properties.Furthermore,our approach enables the synthesis of Pb_(3)S_(2)Br_(2) that had not yet been reported.Our results not only provide valuable insights into the heterogeneous integration of PbYX and PbY materials to elevate material properties but also provide an effective method for further expanding the preparation of PbYX material systems.展开更多
Owing to their low toxicity and remarkable stability, perovskites based on antimony and bismuth have garnered significant interest in recent years. However, A_(3)B_(2)X_(9) perovskite materials derived from antimony a...Owing to their low toxicity and remarkable stability, perovskites based on antimony and bismuth have garnered significant interest in recent years. However, A_(3)B_(2)X_(9) perovskite materials derived from antimony and bismuth face several challenges, including excessively wide band gaps, elevated defect densities, and suboptimal film quality, all of which hinder advancements in device efficiency. While extensive studies have been undertaken to investigate the effects of modulating the A-site and X-site elements in lead-free A_(3)B_(2)X_(9) perovskites, there remains a notable scarcity of reports addressing the impact of modifications to the B-site element. In this study, we investigated the alloying of antimony and bismuth within the 2D Cs_(3)B_(2)I_(6)Br_(3) perovskite. By systematically varying the ratios of two elements, we found that the incorporation of both antimony and bismuth at the B-site significantly enhances the quality of the perovskite films. Our findings indicate that a 1 : 1 ratio of antimony to bismuth produces the densest films, the highest photoluminescence intensity, and superior photovoltaic performance. Ultimately,the devices fabricated using this optimal ratio achieved an open-circuit voltage(VOC) of 1.01 V and a power conversion efficiency(PCE) of 0.645%.展开更多
Objective:Osteoporosis is a systemic metabolic disease characterized by decreased bone mass,deterioration of bone microstructure,and increased fracture risk.Its occurrence is closely related to sex,age,and lifestyle f...Objective:Osteoporosis is a systemic metabolic disease characterized by decreased bone mass,deterioration of bone microstructure,and increased fracture risk.Its occurrence is closely related to sex,age,and lifestyle factors.Environmental exposure to heavy metals and metalloids may also influence its development,although existing findings remain inconsistent.The sex differences in the association between mixed metal exposure and osteoporosis are still unclear.This study aims to investigate whether sex differences exist in the associations between cadmium(Cd),lead(Pb),mercury(Hg),selenium(Se),manganese(Mn),and their mixtures and osteoporosis among men aged≥50 years and postmenopausal women,and to analyze the potential moderating effect of dairy product consumption on these associations.Methods:Data from the National Health and Nutrition Examination Survey(NHANES)2013−2014 and 2017−2018 cycles were used.In men and women separately,generalized linear regression models(univariate regression analysis and multivariate logistic regression)were applied to examine the relationships between single-metal exposure and osteoporosis at the femoral neck and vertebrae.A weighted quantile sum(WQS)model was used to construct a weighted index of mixed metal exposure to quantify the joint effects of multiple metals.Bayesian kernel machine regression(BKMR)was used to systematically evaluate the associations between blood Cd,Pb,Hg,Se,Mn,and their mixtures and osteoporosis at different skeletal sites,capturing potential nonlinear relationships and interactions among metals.Participants were further stratified into high dairy consumption(≥7 times/week)and low dairy consumption(<7 times/week)groups to explore the potential moderating effect of dairy consumption on the association between Cd exposure and osteoporosis.Results:Multivariate logistic regression analysis showed that,in the fully adjusted model,Cd was positively associated with femoral neck osteoporosis in men aged≥50 years[odds ratio(OR)=8.563,95%confidence interval(CI)1.888 to 38.845,P<0.05],whereas Se was negatively associated with femoral neck osteoporosis(OR<0.001,95%CI 0 to 0.150,P<0.05).In postmenopausal women,Cd was positively associated with femoral neck osteoporosis risk(OR=2.148,95%CI 1.038 to 4.443,P<0.05),while Se was negatively associated with femoral neck osteoporosis risk(OR=0.027,95%CI 0.001 to 0.986,P<0.05).No significant association was observed between any metal and vertebral osteoporosis(all P>0.05).The WQS model indicated that mixed metal exposure was positively associated with vertebral osteoporosis in men(OR=1.452,95%CI 0.277 to 2.626,P<0.05),whereas no significant association was observed in women.BKMR analysis showed that mixed metal exposure was positively associated with osteoporosis risk at the femoral neck and vertebrae in men,with Cd contributing most to osteoporosis risk,while no association was observed between mixed metal exposure and osteoporosis risk in women.The positive association between mixed blood metal exposure and osteoporosis risk might be partially offset by Se.In stratified analysis,the association between Cd exposure and osteoporosis was stronger in the high dairy consumption group(OR=1.19,95%CI 0.51 to 2.78,P>0.05)than in the low dairy consumption group(OR=3.12,95%CI 1.84 to 5.30,P<0.05),suggesting that frequent dairy consumption may attenuate the positive association between Cd exposure and femoral neck osteoporosis in women.Conclusion:In men aged≥50 years,mixed metal exposure was positively associated with osteoporosis risk at different skeletal sites(femoral neck and vertebra),with Cd contributing most to the risk.In postmenopausal women,no association between mixed metal exposure and osteoporosis risk was observed,indicating clear sex differences.Selenium and dairy consumption may be potential protective factors for osteoporosis in women,whereas such protective effects were not observed in men.展开更多
Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims ...Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims to mitigate far-field noise.Among these cases,a reduction in the wavelength is found to be advantageous for noise suppression,with the smallest wavelength case achieving a maximum noise reduction of 1.9 dB.Furthermore,the noise radiation induced by WLEs is suppressed mainly at medium frequencies.The theory of multiprocess aeroacoustics is applied to reveal their underlying mechanisms.The dominant factor is the source cutoff effect,which significantly decreases the source strength on hills.Additionally,spanwise decoherence with phase interference serves as another crucial mechanism,particularly for reducing mid-frequency noise.展开更多
Lead(Pb)-zinc(Zn)slags contain large amounts of Pb,causing irreversible damage to the environment.Therefore,developing an effective strategy to extract Pb from Pb-Zn slags and convert them into a renewable high-value ...Lead(Pb)-zinc(Zn)slags contain large amounts of Pb,causing irreversible damage to the environment.Therefore,developing an effective strategy to extract Pb from Pb-Zn slags and convert them into a renewable high-value catalyst not only solves the energy crisis but also reduces environmental pollution.Herein,we present a viable strategy to recycle Pb and iron(Fe)from Pb-Zn slags for the fabrication of efficient methylammonium lead tri-iodide(r-MAPbI_(3))piezocatalysts with single-atom Fe-N_(4) sites.Intriguingly,atomically dispersed Fe sites from Pb-Zn slags,which coordinated with N in the neighboring four CH3NH3 to form the FeN_(4) configuration,were detected in the as-obtained r-MAPbI_(3) by synchrotron X-ray absorption spectroscopy.The introduction of Fe single atoms amplified the polarization of MAPbI_(3) and upshifted the d-band center of MAPbI_(3).This not only enhanced the piezoelectric response of MAPbI_(3) but also promoted the proton transfer during the hydrogen evolution process.Due to the decoration of Fe single atoms,r-MAPbI_(3) showed a pronounced H2 yield of 322.4μmol g^(−1) h^(−1),which was 2.52 times that of MAPbI_(3) synthesized using commercially available reagents.This simple yet robust strategy to manufactureMAPbI_(3) piezocatalysts paves a novel way to the large-scale and value-added consumption of Pb-containing waste residues.展开更多
This study investigates the pharmacokinetics and metabolic characteristics of three marinederived piericidins as potential drug leads for kidney disease:piericidin A(PA)and its two glycosides(GPAs),glucopiericidin A(G...This study investigates the pharmacokinetics and metabolic characteristics of three marinederived piericidins as potential drug leads for kidney disease:piericidin A(PA)and its two glycosides(GPAs),glucopiericidin A(GPA)and 13-hydroxyglucopiericidin A(13-OH-GPA).The research aims to facilitate lead selection and optimization for developing a viable preclinical candidate.Rapid absorption of PA and GPAs in mice was observed,characterized by short half-lives and low bioavailability.Glycosides and hydroxyl groups significantly enhanced the absorption rate(13-OH-GPA>GPA>PA).PA and GPAs exhibited metabolic instability in liver microsomes due to Cytochrome P450 enzymes(CYPs)and uridine diphosphoglucuronosyl transferases(UGTs).Glucuronidation emerged as the primary metabolic pathway,with UGT1A7,UGT1A8,UGT1A9,and UGT1A10 demonstrating high elimination rates(30%-70%)for PA and GPAs.This rapid glucuronidation may contribute to the low bioavailability of GPAs.Despite its low bioavailability(2.69%),13-OH-GPA showed higher kidney distribution(19.8%)compared to PA(10.0%)and GPA(7.3%),suggesting enhanced biological efficacy in kidney diseases.Modifying the C-13 hydroxyl group appears to be a promising approach to improve bioavailability.In conclusion,this study provides valuable metabolic insights for the development and optimization of marine-derived piericidins as potential drug leads for kidney disease.展开更多
Objective:To investigate the protective effect of alpha-lipoic acid on lead-induced Sertoli cell injury and its potential molecular mechanisms using primary Sertoli cells from rooster testes.Methods:Primary Sertoli ce...Objective:To investigate the protective effect of alpha-lipoic acid on lead-induced Sertoli cell injury and its potential molecular mechanisms using primary Sertoli cells from rooster testes.Methods:Primary Sertoli cells from 6-week-old rooster testes were divided into four goups.They were treated with serum-free DMEM-F12 medium(the control group),40μM lead acetate,100μM alpha-lipoic acid,or 40μM lead acetate plus 100μM alpha-lipoic acid for 24 h,respectively.Cell viability,reactive oxygen species levels(DCFH-DA),antioxidant enzyme activities(catalase,superoxide dismutase),blood-testis barrier-related proteins,nuclear factor-erythroid 2-related factor 2(Nrf2)pathway components,proliferation/apoptosis markers(Western blot),and related gene expression(qPCR)were analyzed.Results:Alpha-lipoic acid treatment significantly reduced lead-induced reactive oxygen species(ROS)production by 58.3%compared to the lead acetate group(P<0.05),enhanced catalase activity by 35.8%(P<0.05),and elevated lead-reduced PCNA expression by 47.2%(P<0.05).Lead acetate 40μM plus 100μM alpha-lipoic acid significantly increased Nrf2 expression by 78.9%and HO1/NQO1 expression by 97.5%and 89.4%,respectively(P<0.05),significantly upregulated the expression of Bcl2 protein and significantly downregulated Bax protein expression(P<0.05).Conclusions:Alpha-lipoic acid enhances the antioxidant properties of Sertoli cells by activating the Nrf2 pathway,restores lead-induced excessive autophagy,and inhibits apoptosis,thus alleviating the damage caused by lead in Sertoli cells.展开更多
Microwave digestion-inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the sources of lead in farmland soil and rice in the Jiulongjiang River Basin.The results suggested that the source of lead i...Microwave digestion-inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the sources of lead in farmland soil and rice in the Jiulongjiang River Basin.The results suggested that the source of lead in rice was differ from that in soil.There were four main sources of lead in farmland soil:natural source,agricultural source,industrial source and fossil fuel source,among which natural source,agricultural source and industrial source contributed more.There were four main sources of lead in rice:natural,agricultural,industrial and fossil fuel sources,and more importantly,fossil fuel sources.The comparison of lead isotope composition with potential sources(^(206)Pb/^(207)Pb,^(208)Pb/^(206)Pb,^(208)Pb/^(207)Pb)can provide a scientific basis for the identification and treatment of heavy metal lead pollution sources in farmland soil and rice in the Jiulong River Basin.展开更多
The ionosphere is an important component of the near Earth space environment.The three common methods for detecting the ionosphere with high frequency(HF)radio signals are vertical detection,oblique detection,and obli...The ionosphere is an important component of the near Earth space environment.The three common methods for detecting the ionosphere with high frequency(HF)radio signals are vertical detection,oblique detection,and oblique backscatter detection.The ionograms obtained by these detection methods can effectively reflect a large amount of effective information in the ionosphere.The focus of this article is on the oblique backscatter ionogram obtained by oblique backscatter detection.By extracting the leading edge of the oblique backscatter ionogram,effective information in the ionosphere can be inverted.The key issue is how to accurately obtain the leading edge of the oblique backscatter ionogram.In recent years,the application of pattern recognition has become increasingly widespread,and the YOLO model is one of the best fast object detection algorithms in one-stage.Therefore,the core idea of this article is to use the newer YOLOX object detection algorithm in the YOLO family to perform pattern recognition on the F and E_(s) layers echoes in the oblique backscatter ionogram.After image processing,a single-layer oblique backscatter echoes are obtained.It can be found that the leading edge extraction of the oblique backscatter ionogram obtained after pattern recognition and image processing by the YOLOX model is more fitting to the actual oblique backscatter leading edge.展开更多
Evaluating the stabilized lead(Pb)-contaminated soils through sampling and laboratory testing involves costly and time-consuming processes.Therefore,this study employed a low-cost and non-destructive resistivity tool ...Evaluating the stabilized lead(Pb)-contaminated soils through sampling and laboratory testing involves costly and time-consuming processes.Therefore,this study employed a low-cost and non-destructive resistivity tool to evaluate the Pb-contaminated soils stabilized by electrolytic manganese residue(EMR)-based geopolymer(EG-OPC)from the strength and environmental benefits perspective.First,unconfined compressive strength(UCS)and leaching tests were conducted to study the stabilization effectiveness of EG-OPC.Results indicated that the UCS values of soil(5000 mg/kg of pollutants)stabilized by 20%EG-OPC were 4.87 MPa and 8.13 MPa after 7 d and 60 d of curing,respectively.After 60 d of curing,the Pb concentration in the leachate reached 44 mg/L,far lower than the control group(321 mg/L).Second,soil,pore water,and leachate resistivity(ERS,ERW,and ERL)were measured to establish fitting relationships with strength parameters and pollution risk.The good fitting results(e.g.ERS/ERW versus UCS/secant modulus(E50):correlation coefficient R2 z 0.9,ERS/ERW versus Pb contents:R2 z 0.9,and ERL versus Pb2þconcentration:R2¼0.92)and well used Archie's law(ERS versus ERW:R2>0.9)indicate that the resistivity can be used to evaluate the stabilization effectiveness.Furthermore,the microscopic results revealed two behaviors,demonstrating the reliability of resistivity:(1)with the hydration process,resistivity increases due to a denser structure and lower amounts of free water and Pb ions,and(2)the addition of Pb reduces resistivity due to its inhibition or even destructive effects on cementation and formation of hydration products.展开更多
This paper presented a novel and environmentally friendly approach for recovering platinum group metals(PGMs)from spent automotive exhaust catalysts.The study employed lead slag and waste graphite electrodes as raw ma...This paper presented a novel and environmentally friendly approach for recovering platinum group metals(PGMs)from spent automotive exhaust catalysts.The study employed lead slag and waste graphite electrodes as raw materials,incorporating CaO as an additive to fine-tune the slag's viscosity and density.By reducing FeO in the lead slag using waste graphite electrodes,pure Fe was obtained,effectively trapping the PGMs from the exhausted catalysts.The study explored the effects of reductant addition,trapping duration,slag basicity,and trapping temperature on the recovery rate of PGMs.The results indicated that a maximum recovery rate of 97.86%was achieved when the reductant was added at 1.5 times the theoretical amount,with a trapping duration of 60 minutes,a slag basicity of 0.7,and a trapping temperature of 1600℃.This research offered a greener pathway for the recovery of PGMs from spent automotive exhaust catalysts.展开更多
This study introduces a novel flow-through cowcatcher with integrated inlet and outlet channels as an aerodynamic noise mitigation strategy for the nose car of a high-speed train.The wall-adapting local eddy-viscosity...This study introduces a novel flow-through cowcatcher with integrated inlet and outlet channels as an aerodynamic noise mitigation strategy for the nose car of a high-speed train.The wall-adapting local eddy-viscosity large eddy simulation(WALE-LES)combined with the Ffowcs Williams-Hawkings(FW-H)acoustic analogy approach is employed to evaluate its impact on the aerodynamic and aeroacoustic characteristics of the leading bogie region.Compared with the conventional closed cowcatcher,results show that the flow-through structure suppresses the flow separation,promotes more stable vortex evolution within the bogie cavity,and reduces the spatial extent of high amplitude wall pressure fluctuations up to 40%,mitigating effectively the generation of aerodynamic noise.Semi anechoic wind tunnel experiments validate the simulation results and demonstrate that the sound pressure levels at the far field observers decrease by 0.4-0.6 dB(A)with the flow-through cowcatcher applied underneath the nose car.The dominant sound source around the leading bogie region is shrunk with intensity reduced about 1.0 dB(A).These findings confirm the effectiveness of the flow-through cowcatcher in reducing the aerodynamic noise produced from the leading bogie region,providing both theoretical insight and engineering guidance for structural optimization and low-noise design of the nose car in a high-speed train.展开更多
Climate change has prompted the aviation industry to reduce greenhouse gas emissions.Variable-camber leading edges,with their adaptable aerodynamic shapes,hold significant potential for laminar flow wings and contribu...Climate change has prompted the aviation industry to reduce greenhouse gas emissions.Variable-camber leading edges,with their adaptable aerodynamic shapes,hold significant potential for laminar flow wings and contribute to greener aviation.In response to this need,this paper proposes a design optimization method for a variable-camber leading edge featuring an outer variablethickness composite compliant skin and an inner open-kinematic-chain mechanism.The optimization methodology employs a fiber continuity model based on a ply-drop sequence,a guiding sequence and a thickness sequence to describe the variable-thickness composite compliant skin structure,enabling direct generation of a composite layup sequence that meets fiber continuity criteria.Additionally,the design methodology for the inner open kinematic chain considers the rigidflexible coupling effect and analyzes the number of driving ribs along the span-wise direction.Finally,a full-scale physical prototype for a large-scale civil aircraft is developed and experimented in the FL-10 wind tunnel,demonstrating that the variable-camber leading edge can smoothly and precisely achieve its target shape and hold its final profile under the corresponding aerodynamic loads,thereby validating the proposed design methodology.展开更多
The primary Mach Reflection(MR)and pressure/heating loads on V-shaped Blunt Leading Edges(VBLEs)with variable elliptic cross-sections and conic crotches are theoretically investigated in this study.The simplified cont...The primary Mach Reflection(MR)and pressure/heating loads on V-shaped Blunt Leading Edges(VBLEs)with variable elliptic cross-sections and conic crotches are theoretically investigated in this study.The simplified continuity method is used to forecast the shock configurations.The theoretical predictions and the numerical simulations for the Mach stem and the triple point as well as the curved shock accord well.Based on the theoretical model,an analysis of the impact of the axial ratio a/b of the cross-sectional shape and the eccentricity e of the crotch sweep path on shock structures is carried out.The shock configurations obtained from the theoretical model enable the derivation of the transition boundaries between the primary MR and the same family Regular Reflection(sRR).It is found that the increase of a/b and e can both facilitate the primary MR to sRR transition.The resulting transition and the corresponding generation of the wall pressure and heat flux are then investigated.The results indicate that higher values of the ratio a/b can significantly reduce the wall pressure and heating loads by inducing the primary MR to sRR transition.Conversely,the increase in the eccentricity e results in increased loads,despite causing the same transition.展开更多
The contradiction between the efficiency and the ice tolerance remains a challenge to the traditional aerodynamic design considering the icing effect.To address the problem,a new ice-tolerant concept based on the vari...The contradiction between the efficiency and the ice tolerance remains a challenge to the traditional aerodynamic design considering the icing effect.To address the problem,a new ice-tolerant concept based on the variable drooping leading edge is proposed and extended to a single-aisle commercial aircraft with the swept wing.The outer-wing and full-spanwise drooping leading edge configurations are set up to distinguish the effect of different ice tolerant strategies.The Reynolds-averaged Navier-Stokes results reveal that the stall angle of attack is delayed by 25.0%,and the maximum lift coefficient is increased by 23.3%with the full-spanwise drooping in the presence of horn-shaped ice on the wing.This improvement is primarily driven by the recovery of leading-edge suction.With the formulation of the improved delayed detached eddy simulation,the structures and the behaviors of the separated flow near the stall point are analyzed via the comparison before and after drooping the leading edge in full-spanwise.The results indicate that the suppression of the spatial development of the shedding shear layer promotes the closure of the separation bubble and mitigates the sweeping motion of the large-scale spanwise vortex.These integrated effects contribute to the enhancement of ice tolerance.展开更多
文摘We describe the case of a 77-year-old female who underwent dual-chamber permanent pacemaker implantation using two active screw-in leads for complete atrioventricular block. The two active screw-in leads perforated the atrial and ventricular walls causing cardiac tamponade and a left hemothorax associated with ventricular perforation. An emergency sternotomy was performed to facilitate drainage and hemostasis. Although hemothorax due to pacing lead perforation is very rare, such a possibility should always be considered.
文摘China’s shipbuilding industry maintained the world’s largest market share in terms of three major indicators for the 16th consecutive year in 2025,according to data released by the Ministry of Industry and Information Technology on 1 February.
基金funded by the Research Fund of National Key Laboratory of Aerospace Physics in Fluids,grant number 2024-APF-KFZD-01Guangdong Basic and Applied Basic Research Foundation,grant number 2025A1515012081+1 种基金National Natural Science Foundation of China,grant number 12002193Shandong Provincial Natural Science Foundation,China,grant number ZR2019QA018.
文摘For hypersonic air-breathing vehicles,the V-shaped leading edges(VSLEs)of supersonic combustion ramjet(scramjet)inlets experience complex shock interactions and intense aerodynamic loads.This paper provides a comprehensive review of flow characteristics at the crotch of VSLEs,with particular focus on the transition of shock interaction types and the variation of wall heat flux under different freestream Mach numbers and geometric configurations.The mechanisms governing shock transition,unsteady oscillations,hysteresis,and three-dimensional effects in VSLE flows are first examined.Subsequently,thermal protection strategies aimed at mitigating extreme heating loads are reviewed,emphasizing their relevance to practical engineering applications.Special attention is given to recent studies addressing thermochemical nonequilibrium effects on VSLE shock interactions,and the limitations of current research are critically assessed.Finally,perspectives for future investigations into hypersonic VSLE shock interactions are outlined,highlighting opportunities for advancing design and thermal management strategies.
基金financial support from the Shccig-Qinling Program(SMYJY202300294C)the Science,Technology,and Innovation Commission of Shenzhen Municipality(GJHZ20220913143204008,JCYJ20220818103417036)+1 种基金the National Natural Science Foundation of China(22261142666,52172237,52372225)the Shaanxi Science Fund for Distinguished Young Scholars(2022JC-21)。
文摘Although lead(Pb)-based perovskite solar cells(PSCs)have garnered intense attention for their remarkable photovoltaic conversion efficiency,their commercial process is urgently in need of an effective damage-evaluation system for the early diagnosis of faulty PSCs.The main cause of microdamage in perovskite films is the outflow of Pb,which significantly impacts device performance.However,no reliable correlation has been established between classical damage detection techniques and Pb detection,resulting in limited detection sensitivity.Here,we report an in situ visual microdamage evaluation method of PSCs by coating the device surface with a silica gel encapsulation layer containing porphyrin molecules.This detection technology enables high selectivity and sensitivity based on the strong complexation between the porphyrin ring and trace Pb outflow from degraded PSCs.By establishing the linear relationship between the fluorescence intensity and Pb concentration in PSCs,trace Pb outflow is pinpointed and quantified with a low detection limit of 0.65μg cm^(-2).An applet is developed for the insitu visual fluorescence detection method to facilitate the continuous real-time monitoring of series-type PSCs,thereby enabling the prompt identification and replacement of damaged PSCs and ensuring the swift restoration of high efficiency.
文摘This study investigates the potential of Prosopis cineraria Leaves Powder(PCLP)as a biosorbent for removing lead(Pb)and zinc(Zn)from aqueous solutions,optimizing the process using Response Surface Methodology(RSM).Prosopis cineraria,commonly known as Khejri,is a drought-resistant tree with significant promise in environmental applications.The research employed a Central Composite Design(CCD)to examine the independent and combined effects of key process variables,including initial metal ion concentration,contact time,pH,and PCLP dosage.RSM was used to develop mathematical models that explain the relationship between these factors and the efficiency of metal removal,allowing the determination of optimal operating conditions.The experimental results indicated that the Langmuir isotherm model was the most appropriate for describing the biosorption of both metals,suggesting favorable adsorption characteristics.Additionally,the D-R isotherm confirmed that chemisorption was the primary mechanism involved in the biosorption process.For lead removal,the optimal conditions were found to be 312.23 K temperature,pH 4.72,58.5 mg L-1 initial concentration,and 0.27 g biosorbent dosage,achieving an 83.77%removal efficiency.For zinc,the optimal conditions were 312.4 K,pH 5.86,53.07 mg L-1 initial concentration,and the same biosorbent dosage,resulting in a 75.86%removal efficiency.These findings highlight PCLP’s potential as an effective,eco-friendly biosorbent for sustainable heavy metal removal in water treatment.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0110300)the National Natural Science Foundation of China(Grant Nos.52372215,92163114,and 52202274)+5 种基金the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20230504)the Special Fund for the"Dual Carbon"Science and Technology Innovation of Jiangsu province(Industrial Prospect and Key Technology Research program)(Grant Nos.BE2022023 and BE2022021)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.21KJA430004)Gusu Innovation and Entre preneurship Leading Talent Program(Grant No.ZXL2022451)the China Postdoctoral Science Foundation(Grant No.2023M732523)supported by Suzhou Key Laboratory of Functional Nano&Soft Materials,Collaborative Innovation Center of Suzhou Nano Science&Technology,the 111 Project.
文摘Lead chalcohalides(PbYX,X=Cl,Br,I;Y=S,Se)is an extension of the classic Pb chalcogenides(PbY).Constructing the heterogeneous integration with PbYX and PbY material systems makes it possible to achieve significantly improved optoelectronic performance.In this work,we studied the effect of introducing halogen precursors on the structure of classical PbS nanocrystals(NCs)during the synthesis process and realized the preparation of PbS/Pb_(3)S_(2)X_(2) core/shell structure for the first time.The core/shell structure can effectively improve their optical properties.Furthermore,our approach enables the synthesis of Pb_(3)S_(2)Br_(2) that had not yet been reported.Our results not only provide valuable insights into the heterogeneous integration of PbYX and PbY materials to elevate material properties but also provide an effective method for further expanding the preparation of PbYX material systems.
基金financially supported by the Natural Science Foundation of Zhejiang Province, China (Grant No. LQ22F040001)China Postdoctoral Science Foundation (Grant No. 2022M723281)Science and Technology Planning Project of Shaoxing City (Grant No. 2023B41006)。
文摘Owing to their low toxicity and remarkable stability, perovskites based on antimony and bismuth have garnered significant interest in recent years. However, A_(3)B_(2)X_(9) perovskite materials derived from antimony and bismuth face several challenges, including excessively wide band gaps, elevated defect densities, and suboptimal film quality, all of which hinder advancements in device efficiency. While extensive studies have been undertaken to investigate the effects of modulating the A-site and X-site elements in lead-free A_(3)B_(2)X_(9) perovskites, there remains a notable scarcity of reports addressing the impact of modifications to the B-site element. In this study, we investigated the alloying of antimony and bismuth within the 2D Cs_(3)B_(2)I_(6)Br_(3) perovskite. By systematically varying the ratios of two elements, we found that the incorporation of both antimony and bismuth at the B-site significantly enhances the quality of the perovskite films. Our findings indicate that a 1 : 1 ratio of antimony to bismuth produces the densest films, the highest photoluminescence intensity, and superior photovoltaic performance. Ultimately,the devices fabricated using this optimal ratio achieved an open-circuit voltage(VOC) of 1.01 V and a power conversion efficiency(PCE) of 0.645%.
基金supported by the Science and Technology Innovation Program of Hunan Province(2025RC3061)the Natural Science Foundation of Hunan Province(2022JJ30828)+2 种基金the Grants from Hunan Provincial Clinical Medicine Research Center for Intelligent Management of Chronic Disease(2023SK4042)the Innovation Foundation For Postgraduate of Hunan Province(CX20240310)the Postgraduate Innovative Project of Central South University(2023XQLH183),China。
文摘Objective:Osteoporosis is a systemic metabolic disease characterized by decreased bone mass,deterioration of bone microstructure,and increased fracture risk.Its occurrence is closely related to sex,age,and lifestyle factors.Environmental exposure to heavy metals and metalloids may also influence its development,although existing findings remain inconsistent.The sex differences in the association between mixed metal exposure and osteoporosis are still unclear.This study aims to investigate whether sex differences exist in the associations between cadmium(Cd),lead(Pb),mercury(Hg),selenium(Se),manganese(Mn),and their mixtures and osteoporosis among men aged≥50 years and postmenopausal women,and to analyze the potential moderating effect of dairy product consumption on these associations.Methods:Data from the National Health and Nutrition Examination Survey(NHANES)2013−2014 and 2017−2018 cycles were used.In men and women separately,generalized linear regression models(univariate regression analysis and multivariate logistic regression)were applied to examine the relationships between single-metal exposure and osteoporosis at the femoral neck and vertebrae.A weighted quantile sum(WQS)model was used to construct a weighted index of mixed metal exposure to quantify the joint effects of multiple metals.Bayesian kernel machine regression(BKMR)was used to systematically evaluate the associations between blood Cd,Pb,Hg,Se,Mn,and their mixtures and osteoporosis at different skeletal sites,capturing potential nonlinear relationships and interactions among metals.Participants were further stratified into high dairy consumption(≥7 times/week)and low dairy consumption(<7 times/week)groups to explore the potential moderating effect of dairy consumption on the association between Cd exposure and osteoporosis.Results:Multivariate logistic regression analysis showed that,in the fully adjusted model,Cd was positively associated with femoral neck osteoporosis in men aged≥50 years[odds ratio(OR)=8.563,95%confidence interval(CI)1.888 to 38.845,P<0.05],whereas Se was negatively associated with femoral neck osteoporosis(OR<0.001,95%CI 0 to 0.150,P<0.05).In postmenopausal women,Cd was positively associated with femoral neck osteoporosis risk(OR=2.148,95%CI 1.038 to 4.443,P<0.05),while Se was negatively associated with femoral neck osteoporosis risk(OR=0.027,95%CI 0.001 to 0.986,P<0.05).No significant association was observed between any metal and vertebral osteoporosis(all P>0.05).The WQS model indicated that mixed metal exposure was positively associated with vertebral osteoporosis in men(OR=1.452,95%CI 0.277 to 2.626,P<0.05),whereas no significant association was observed in women.BKMR analysis showed that mixed metal exposure was positively associated with osteoporosis risk at the femoral neck and vertebrae in men,with Cd contributing most to osteoporosis risk,while no association was observed between mixed metal exposure and osteoporosis risk in women.The positive association between mixed blood metal exposure and osteoporosis risk might be partially offset by Se.In stratified analysis,the association between Cd exposure and osteoporosis was stronger in the high dairy consumption group(OR=1.19,95%CI 0.51 to 2.78,P>0.05)than in the low dairy consumption group(OR=3.12,95%CI 1.84 to 5.30,P<0.05),suggesting that frequent dairy consumption may attenuate the positive association between Cd exposure and femoral neck osteoporosis in women.Conclusion:In men aged≥50 years,mixed metal exposure was positively associated with osteoporosis risk at different skeletal sites(femoral neck and vertebra),with Cd contributing most to the risk.In postmenopausal women,no association between mixed metal exposure and osteoporosis risk was observed,indicating clear sex differences.Selenium and dairy consumption may be potential protective factors for osteoporosis in women,whereas such protective effects were not observed in men.
基金supported by the National Natural Science Foundation of China(12322210,12172351,92252202,and 12388101)the Fundamental Research Funds for the Central Universities.
文摘Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims to mitigate far-field noise.Among these cases,a reduction in the wavelength is found to be advantageous for noise suppression,with the smallest wavelength case achieving a maximum noise reduction of 1.9 dB.Furthermore,the noise radiation induced by WLEs is suppressed mainly at medium frequencies.The theory of multiprocess aeroacoustics is applied to reveal their underlying mechanisms.The dominant factor is the source cutoff effect,which significantly decreases the source strength on hills.Additionally,spanwise decoherence with phase interference serves as another crucial mechanism,particularly for reducing mid-frequency noise.
基金supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004,U23B20166)Guangdong Basic and Applied Basic Research Foundation(2024A1515030039,2025A1515010312).
文摘Lead(Pb)-zinc(Zn)slags contain large amounts of Pb,causing irreversible damage to the environment.Therefore,developing an effective strategy to extract Pb from Pb-Zn slags and convert them into a renewable high-value catalyst not only solves the energy crisis but also reduces environmental pollution.Herein,we present a viable strategy to recycle Pb and iron(Fe)from Pb-Zn slags for the fabrication of efficient methylammonium lead tri-iodide(r-MAPbI_(3))piezocatalysts with single-atom Fe-N_(4) sites.Intriguingly,atomically dispersed Fe sites from Pb-Zn slags,which coordinated with N in the neighboring four CH3NH3 to form the FeN_(4) configuration,were detected in the as-obtained r-MAPbI_(3) by synchrotron X-ray absorption spectroscopy.The introduction of Fe single atoms amplified the polarization of MAPbI_(3) and upshifted the d-band center of MAPbI_(3).This not only enhanced the piezoelectric response of MAPbI_(3) but also promoted the proton transfer during the hydrogen evolution process.Due to the decoration of Fe single atoms,r-MAPbI_(3) showed a pronounced H2 yield of 322.4μmol g^(−1) h^(−1),which was 2.52 times that of MAPbI_(3) synthesized using commercially available reagents.This simple yet robust strategy to manufactureMAPbI_(3) piezocatalysts paves a novel way to the large-scale and value-added consumption of Pb-containing waste residues.
基金supported by the Special Project for Marine Economic Development of Department of Natural Resources of Guangdong Province(No.GDNRC[2024]25)National Natural Science Foundation of China(Nos.82274002,U20A20101)+1 种基金Guangdong Local Innovation Team Program(No.2019BT02Y262)Science and Technology Innovation Project of Guangdong Medical Products Administration(Nos.S2021ZDZ042,2023ZDZ06,2024-ZDZ08,2024A1515012477)。
文摘This study investigates the pharmacokinetics and metabolic characteristics of three marinederived piericidins as potential drug leads for kidney disease:piericidin A(PA)and its two glycosides(GPAs),glucopiericidin A(GPA)and 13-hydroxyglucopiericidin A(13-OH-GPA).The research aims to facilitate lead selection and optimization for developing a viable preclinical candidate.Rapid absorption of PA and GPAs in mice was observed,characterized by short half-lives and low bioavailability.Glycosides and hydroxyl groups significantly enhanced the absorption rate(13-OH-GPA>GPA>PA).PA and GPAs exhibited metabolic instability in liver microsomes due to Cytochrome P450 enzymes(CYPs)and uridine diphosphoglucuronosyl transferases(UGTs).Glucuronidation emerged as the primary metabolic pathway,with UGT1A7,UGT1A8,UGT1A9,and UGT1A10 demonstrating high elimination rates(30%-70%)for PA and GPAs.This rapid glucuronidation may contribute to the low bioavailability of GPAs.Despite its low bioavailability(2.69%),13-OH-GPA showed higher kidney distribution(19.8%)compared to PA(10.0%)and GPA(7.3%),suggesting enhanced biological efficacy in kidney diseases.Modifying the C-13 hydroxyl group appears to be a promising approach to improve bioavailability.In conclusion,this study provides valuable metabolic insights for the development and optimization of marine-derived piericidins as potential drug leads for kidney disease.
基金funded by Zhejiang Provincial Natural Science Foundation of China under Grant No.LTGN24C170001Zhejiang Province Vocational Education Teaching Reform Project jg20230038+1 种基金Zhejiang Province Education Science Planning Project 2024JCD034Jinhua Science and Technology Plan Project 2024-2-002.
文摘Objective:To investigate the protective effect of alpha-lipoic acid on lead-induced Sertoli cell injury and its potential molecular mechanisms using primary Sertoli cells from rooster testes.Methods:Primary Sertoli cells from 6-week-old rooster testes were divided into four goups.They were treated with serum-free DMEM-F12 medium(the control group),40μM lead acetate,100μM alpha-lipoic acid,or 40μM lead acetate plus 100μM alpha-lipoic acid for 24 h,respectively.Cell viability,reactive oxygen species levels(DCFH-DA),antioxidant enzyme activities(catalase,superoxide dismutase),blood-testis barrier-related proteins,nuclear factor-erythroid 2-related factor 2(Nrf2)pathway components,proliferation/apoptosis markers(Western blot),and related gene expression(qPCR)were analyzed.Results:Alpha-lipoic acid treatment significantly reduced lead-induced reactive oxygen species(ROS)production by 58.3%compared to the lead acetate group(P<0.05),enhanced catalase activity by 35.8%(P<0.05),and elevated lead-reduced PCNA expression by 47.2%(P<0.05).Lead acetate 40μM plus 100μM alpha-lipoic acid significantly increased Nrf2 expression by 78.9%and HO1/NQO1 expression by 97.5%and 89.4%,respectively(P<0.05),significantly upregulated the expression of Bcl2 protein and significantly downregulated Bax protein expression(P<0.05).Conclusions:Alpha-lipoic acid enhances the antioxidant properties of Sertoli cells by activating the Nrf2 pathway,restores lead-induced excessive autophagy,and inhibits apoptosis,thus alleviating the damage caused by lead in Sertoli cells.
基金Supported by Natural Science Foundation of Fujian Province(2023J011667)Natural Science Foundation of Xiamen(3502Z202374084).
文摘Microwave digestion-inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the sources of lead in farmland soil and rice in the Jiulongjiang River Basin.The results suggested that the source of lead in rice was differ from that in soil.There were four main sources of lead in farmland soil:natural source,agricultural source,industrial source and fossil fuel source,among which natural source,agricultural source and industrial source contributed more.There were four main sources of lead in rice:natural,agricultural,industrial and fossil fuel sources,and more importantly,fossil fuel sources.The comparison of lead isotope composition with potential sources(^(206)Pb/^(207)Pb,^(208)Pb/^(206)Pb,^(208)Pb/^(207)Pb)can provide a scientific basis for the identification and treatment of heavy metal lead pollution sources in farmland soil and rice in the Jiulong River Basin.
基金Supported by the National Natural Science Foundation of China(42104151,42074184,42188101,41727804)。
文摘The ionosphere is an important component of the near Earth space environment.The three common methods for detecting the ionosphere with high frequency(HF)radio signals are vertical detection,oblique detection,and oblique backscatter detection.The ionograms obtained by these detection methods can effectively reflect a large amount of effective information in the ionosphere.The focus of this article is on the oblique backscatter ionogram obtained by oblique backscatter detection.By extracting the leading edge of the oblique backscatter ionogram,effective information in the ionosphere can be inverted.The key issue is how to accurately obtain the leading edge of the oblique backscatter ionogram.In recent years,the application of pattern recognition has become increasingly widespread,and the YOLO model is one of the best fast object detection algorithms in one-stage.Therefore,the core idea of this article is to use the newer YOLOX object detection algorithm in the YOLO family to perform pattern recognition on the F and E_(s) layers echoes in the oblique backscatter ionogram.After image processing,a single-layer oblique backscatter echoes are obtained.It can be found that the leading edge extraction of the oblique backscatter ionogram obtained after pattern recognition and image processing by the YOLOX model is more fitting to the actual oblique backscatter leading edge.
基金supported by the National Key R&D Program of China(Grant No.2022YFC3901204)the Foundation for Distinguished Young Scholars of Hubei Province,China(Grant No.2021CFA096)the National Natural Science Foundation of China(Grant No.U20A20320).
文摘Evaluating the stabilized lead(Pb)-contaminated soils through sampling and laboratory testing involves costly and time-consuming processes.Therefore,this study employed a low-cost and non-destructive resistivity tool to evaluate the Pb-contaminated soils stabilized by electrolytic manganese residue(EMR)-based geopolymer(EG-OPC)from the strength and environmental benefits perspective.First,unconfined compressive strength(UCS)and leaching tests were conducted to study the stabilization effectiveness of EG-OPC.Results indicated that the UCS values of soil(5000 mg/kg of pollutants)stabilized by 20%EG-OPC were 4.87 MPa and 8.13 MPa after 7 d and 60 d of curing,respectively.After 60 d of curing,the Pb concentration in the leachate reached 44 mg/L,far lower than the control group(321 mg/L).Second,soil,pore water,and leachate resistivity(ERS,ERW,and ERL)were measured to establish fitting relationships with strength parameters and pollution risk.The good fitting results(e.g.ERS/ERW versus UCS/secant modulus(E50):correlation coefficient R2 z 0.9,ERS/ERW versus Pb contents:R2 z 0.9,and ERL versus Pb2þconcentration:R2¼0.92)and well used Archie's law(ERS versus ERW:R2>0.9)indicate that the resistivity can be used to evaluate the stabilization effectiveness.Furthermore,the microscopic results revealed two behaviors,demonstrating the reliability of resistivity:(1)with the hydration process,resistivity increases due to a denser structure and lower amounts of free water and Pb ions,and(2)the addition of Pb reduces resistivity due to its inhibition or even destructive effects on cementation and formation of hydration products.
基金Funded by the Natural Science Foundation of Henan(No.252300421563)the Key Research Projects of Henan Provincial Colleges and Universities(No.25B450001)+3 种基金the Basic and Frontier Research Project of Nanyang(No.24JCQY032)National Natural Science Foundation of China(No.52201044)the Key Specialized Research&Development and Promotion Project(Scientific and Technological Project)of Henan Province(No.232102221022)the Basic and Frontier Technology Research Project of Nanyang(No.23JCQY1001)。
文摘This paper presented a novel and environmentally friendly approach for recovering platinum group metals(PGMs)from spent automotive exhaust catalysts.The study employed lead slag and waste graphite electrodes as raw materials,incorporating CaO as an additive to fine-tune the slag's viscosity and density.By reducing FeO in the lead slag using waste graphite electrodes,pure Fe was obtained,effectively trapping the PGMs from the exhausted catalysts.The study explored the effects of reductant addition,trapping duration,slag basicity,and trapping temperature on the recovery rate of PGMs.The results indicated that a maximum recovery rate of 97.86%was achieved when the reductant was added at 1.5 times the theoretical amount,with a trapping duration of 60 minutes,a slag basicity of 0.7,and a trapping temperature of 1600℃.This research offered a greener pathway for the recovery of PGMs from spent automotive exhaust catalysts.
基金Projects(51875411,52232013)supported by the National Natural Science Foundation of ChinaProject(19DZ2290400)supported by the Shanghai Professional Technical Service Platform Program,China。
文摘This study introduces a novel flow-through cowcatcher with integrated inlet and outlet channels as an aerodynamic noise mitigation strategy for the nose car of a high-speed train.The wall-adapting local eddy-viscosity large eddy simulation(WALE-LES)combined with the Ffowcs Williams-Hawkings(FW-H)acoustic analogy approach is employed to evaluate its impact on the aerodynamic and aeroacoustic characteristics of the leading bogie region.Compared with the conventional closed cowcatcher,results show that the flow-through structure suppresses the flow separation,promotes more stable vortex evolution within the bogie cavity,and reduces the spatial extent of high amplitude wall pressure fluctuations up to 40%,mitigating effectively the generation of aerodynamic noise.Semi anechoic wind tunnel experiments validate the simulation results and demonstrate that the sound pressure levels at the far field observers decrease by 0.4-0.6 dB(A)with the flow-through cowcatcher applied underneath the nose car.The dominant sound source around the leading bogie region is shrunk with intensity reduced about 1.0 dB(A).These findings confirm the effectiveness of the flow-through cowcatcher in reducing the aerodynamic noise produced from the leading bogie region,providing both theoretical insight and engineering guidance for structural optimization and low-noise design of the nose car in a high-speed train.
基金supported by the National Research Project“Variable CAmber wing TechNology(VCAN)”,China。
文摘Climate change has prompted the aviation industry to reduce greenhouse gas emissions.Variable-camber leading edges,with their adaptable aerodynamic shapes,hold significant potential for laminar flow wings and contribute to greener aviation.In response to this need,this paper proposes a design optimization method for a variable-camber leading edge featuring an outer variablethickness composite compliant skin and an inner open-kinematic-chain mechanism.The optimization methodology employs a fiber continuity model based on a ply-drop sequence,a guiding sequence and a thickness sequence to describe the variable-thickness composite compliant skin structure,enabling direct generation of a composite layup sequence that meets fiber continuity criteria.Additionally,the design methodology for the inner open kinematic chain considers the rigidflexible coupling effect and analyzes the number of driving ribs along the span-wise direction.Finally,a full-scale physical prototype for a large-scale civil aircraft is developed and experimented in the FL-10 wind tunnel,demonstrating that the variable-camber leading edge can smoothly and precisely achieve its target shape and hold its final profile under the corresponding aerodynamic loads,thereby validating the proposed design methodology.
基金support of the National Natural Science Foundation of China(Nos.U20A2069,12302389,12372295)the Natural Science Foundation of Fujian Province,China(No.2023J01046)。
文摘The primary Mach Reflection(MR)and pressure/heating loads on V-shaped Blunt Leading Edges(VBLEs)with variable elliptic cross-sections and conic crotches are theoretically investigated in this study.The simplified continuity method is used to forecast the shock configurations.The theoretical predictions and the numerical simulations for the Mach stem and the triple point as well as the curved shock accord well.Based on the theoretical model,an analysis of the impact of the axial ratio a/b of the cross-sectional shape and the eccentricity e of the crotch sweep path on shock structures is carried out.The shock configurations obtained from the theoretical model enable the derivation of the transition boundaries between the primary MR and the same family Regular Reflection(sRR).It is found that the increase of a/b and e can both facilitate the primary MR to sRR transition.The resulting transition and the corresponding generation of the wall pressure and heat flux are then investigated.The results indicate that higher values of the ratio a/b can significantly reduce the wall pressure and heating loads by inducing the primary MR to sRR transition.Conversely,the increase in the eccentricity e results in increased loads,despite causing the same transition.
基金co-supported by the National Natural Science Foundation of China(Nos.12302300,12272312,12372288 and 12388101)the Open Fund of Key Laboratory of Icing and Anti/De-icing,China(No.IADL20220413)the 1-0 Major Engineering Science Problem Project of Northwestern Polytechnical University(No.G2024KY0613)。
文摘The contradiction between the efficiency and the ice tolerance remains a challenge to the traditional aerodynamic design considering the icing effect.To address the problem,a new ice-tolerant concept based on the variable drooping leading edge is proposed and extended to a single-aisle commercial aircraft with the swept wing.The outer-wing and full-spanwise drooping leading edge configurations are set up to distinguish the effect of different ice tolerant strategies.The Reynolds-averaged Navier-Stokes results reveal that the stall angle of attack is delayed by 25.0%,and the maximum lift coefficient is increased by 23.3%with the full-spanwise drooping in the presence of horn-shaped ice on the wing.This improvement is primarily driven by the recovery of leading-edge suction.With the formulation of the improved delayed detached eddy simulation,the structures and the behaviors of the separated flow near the stall point are analyzed via the comparison before and after drooping the leading edge in full-spanwise.The results indicate that the suppression of the spatial development of the shedding shear layer promotes the closure of the separation bubble and mitigates the sweeping motion of the large-scale spanwise vortex.These integrated effects contribute to the enhancement of ice tolerance.
