Creep is one of the most typical failure modes for the turbine blades of an aero-engine.The microstructure of the turbine blades after long-term service can be adjusted by rejuvenation heat treatment(RHT)to restore it...Creep is one of the most typical failure modes for the turbine blades of an aero-engine.The microstructure of the turbine blades after long-term service can be adjusted by rejuvenation heat treatment(RHT)to restore its creep properties.In this work,a series of RHT experiments were carried out on a directionally solidified(DS)nickel-based superalloy under different solution temperatures and primary aging temperatures based on the standard heat treatment(SHT)process parameters to investigate the mechanism of temperature influence on DS's microstructure after RHT.It is indicated that a more uniform microstructure can be obtained under higher solution temperatures and lower primary aging temperatures compared to the SHT process.Furthermore,by employing the image processing methods to quantify microstructural parameters,a comprehensive indicator parameter for the RHT effect(marked as Prej)was proposed to characterize the effects of RHT on DS superalloy's microstructure and creep property combined with the entropy weight method.Based on this,a regression model to describe the relationship between RHT process parameters and Prej was constructed by using the response surface methodology(RSM).It is revealed that the optimal solution temperature and primary aging temperature for this DS superalloy are 1283°C and 1095°C,respectively.Then the conclusion was validated through complete creep experiments on the DS superalloy,which showed the creep life after RHT reaches 95.5%of the SHT specimen,and the total life has increased by 20.6%.展开更多
The key transcription factor gene PdP apE RF109 was cloned from Populus davidiana×P.alba var.pyramidalis(Pdpap),and after overexpression of P dP ap ERF109 in transformants,the gene functions in the resistance res...The key transcription factor gene PdP apE RF109 was cloned from Populus davidiana×P.alba var.pyramidalis(Pdpap),and after overexpression of P dP ap ERF109 in transformants,the gene functions in the resistance response to Fusarium oxysporum infection.Compared with the wild Pdpap,after inoculation with F.oxysporum,the physiological and biochemical characteristics,including relative fresh weight,peroxidase activity,and the percentage of electrolyte leakage showed that,after overexpression of the PdPapERF109 gene,the transformants grew well and displayed significant resistance to F.oxysporum infection.By comparing the reactive oxygen species scavenging capacity of Pdpap plants after pathogen infection,the P dPapERF109-overexpressing plants had significantly better reactive oxygen species scavenging ability than the wild plants.Comprehensive analysis of plant morphology and various physiological and biochemical parameters showed that the overexpression of the P dpapERF109 gene significantly improved the resistance of Pdpap plants to F.oxysporum root rot.Therefore,increasing the expression of the homologous ERF109 gene can be an effective strategy to increase disease resistance in hybrid poplars.展开更多
The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate b...The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate because of dynamic shear failure and extrusion.A new empirical model was presented to predict the perforation diameter in thin plates impacted by high-velocity cylindrical projectiles.The fitting coefficients resulted in a root-mean-square of 0.0641 and a correlation coefficient of 0.991.The errors between the predicted and the experimental values were less than 7.251%,and less than 4.705%for 93.333%cases of the dataset.The accuracy of the proposed model is much higher than that of Hill's model.Compared with historical equations,the new model is more accurate and can well describe the variations of different parameters with the normalized penetrated hole.The model takes into account the strength of materials,which contributes to the excellent results.This paper could provide important theoretical support for the analysis of the perforation process and its mechanism.展开更多
Background Data-driven event analysis has gradually become the backbone of modern competitive sports analysis. Competitive sports data analysis tasks increasingly use computer vision and machine-learning models for in...Background Data-driven event analysis has gradually become the backbone of modern competitive sports analysis. Competitive sports data analysis tasks increasingly use computer vision and machine-learning models for intelligent data analysis. Existing sports visualization systems focus on the player–team data visualization, which is not intuitive enough for team season win–loss data and game time-series data visualization and neglects the prediction of all-star players. Methods This study used an interactive visualization system designed with parallel aggregated ordered hypergraph dynamic hypergraphs, Calliope visualization data story technology,and i Storyline narrative visualization technology to visualize the regular statistics and game time data of players and teams. NPIPVis includes dynamic hypergraphs of a team’s wins and losses and game plot narrative visualization components. In addition, an integrated learning-based all-star player prediction model, SRR-voting, which starts from the existing minority and majority samples, was proposed using the synthetic minority oversampling technique and Random Under Sampler methods to generate and eliminate samples of a certain size to balance the number of allstar and average players in the datasets. Next, a random forest algorithm was introduced to extract and construct the features of players and combined with the voting integrated model to predict the all-star players, using GridSearch CV, to optimize the hyperparameters of each model in integrated learning and then combined with five-fold cross-validation to improve the generalization ability of the model. Finally, the SHapley Additive ex Planations(SHAP) model was introduced to enhance the interpretability of the model. Results The experimental results of comparing the SRR-voting model with six common models show that the accuracy, F1-score, and recall metrics are significantly improved, which verifies the effectiveness and practicality of the SRR-voting model. Conclusions This study combines data visualization and machine learning to design a National Basketball Association data visualization system to help the general audience visualize game data and predict all-star players;this can also be extended to other sports events or related fields.展开更多
Traditional Chinese medicine(TCM)serves as a treasure trove of ancient knowledge,holding a crucial position in the medical field.However,the exploration of TCM's extensive information has been hindered by challeng...Traditional Chinese medicine(TCM)serves as a treasure trove of ancient knowledge,holding a crucial position in the medical field.However,the exploration of TCM's extensive information has been hindered by challenges related to data standardization,completeness,and accuracy,primarily due to the decen-tralized distribution of TCM resources.To address these issues,we developed a platform for TCM knowledge discovery(TCMKD,https://cbcb.cdutcm.edu.cn/TCMKD/).Seven types of data,including syndromes,formulas,Chinese patent drugs(CPDs),Chinese medicinal materials(CMMs),ingredients,targets,and diseases,were manually proofread and consolidated within TCMKD.To strengthen the integration of TCM with modern medicine,TCMKD employs analytical methods such as TCM data mining,enrichment analysis,and network localization and separation.These tools help elucidate the molecular-level commonalities between TCM and contemporary scientific insights.In addition to its analytical capabilities,a quick question and answer(Q&A)system is also embedded within TCMKD to query the database efficiently,thereby improving the interactivity of the platform.The platform also provides a TCM text annotation tool,offering a simple and efficient method for TCM text mining.Overall,TCMKD not only has the potential to become a pivotal repository for TCM,delving into the pharmaco-logical foundations of TCM treatments,but its flexible embedded tools and algorithms can also be applied to the study of other traditional medical systems,extending beyond just TCM.展开更多
Based on the dynamic shock response of the material and structure,the hypervelocity impact processes and mechanisms of long composite rods with axial density/impedance gradients penetration into fourlayer targets were...Based on the dynamic shock response of the material and structure,the hypervelocity impact processes and mechanisms of long composite rods with axial density/impedance gradients penetration into fourlayer targets were studied through experiments and numerical simulation methods.The propagation law of the shock waves,together with the structural responses of the projectiles and targets,the formation and evolution of the fragment groups formed during the processes and their distributions were described.The damage of each target plate was quantitatively analysed by comparing the results of the experiment and numerical simulation.The results showed that the axial density/impedance gradient projectiles could decrease the impact pressure to a certain extent,and the degree of damage to the target plate decreased layer by layer when the head density/impedance of the projectile was high.When the head density/impedance of the projectile was low,the degree of target damage first increased layer by layer until the projectile was completely eroded and then it decreased.The results can provide a reference for the design and application of long rods with axial composite structure for velocities ranging from 6 to 10 Ma or greater.展开更多
The loosening of implant due to bacterial infection brings great difficulties to the implantation of bionic titanium devices.In this study,the Zeolitic Imidazolate Framework 8(ZIF-8)and silver ions were added to the s...The loosening of implant due to bacterial infection brings great difficulties to the implantation of bionic titanium devices.In this study,the Zeolitic Imidazolate Framework 8(ZIF-8)and silver ions were added to the surface of titanium alloy to obtain a uniform coating,which has nice biological activity and antibacterial property.The material structure characterizations,such as X-ray diffraction(XRD),scanning electron microscope(SEM),X-ray photoelectron spectroscopy(XPS),proved that titanium is successfully modified with ZIF-8 and silver ions.It has micro-and nano-level characteristics,rough porous morphology,and excellent apatite inducing ability.The water contact angle experiment shows that the addition of ZIF-8 greatly increases the hydrophilicity of material,which provides conditions for the attachment of osteoblasts.The polarization curve obtained from the electrochemical test proves that the addition of ZIF-8 coating improves the corrosion resistance of titanium.The release of silver ion has a strong growth inhibitory effect on E.coli,and exhibits excellent antibacterial properties.Therefore,the preparation of ZIF-8/Ag coatings on 3D printed titanium provides a new option for the development of orthopedic implants.展开更多
Computational fluid dynamics(CFD)has become the main method for the prediction of the properties of the external wind environment in cities and other urban contexts.A review is presented of the existing literature in ...Computational fluid dynamics(CFD)has become the main method for the prediction of the properties of the external wind environment in cities and other urban contexts.A review is presented of the existing literature in terms of boundary conditions,building models,computational domains,computational grids,and turbulence models.Some specific issues,such as the accuracy/computational cost ratio and the exploitation of existing empirical correlations,are also examined.展开更多
With the considerable applications of ceramic matrix composites(CMC) in aircraft engineering, the design of CMC bolted joint gains paramount attention because of its capacity to to improve load-bearing efficiency of a...With the considerable applications of ceramic matrix composites(CMC) in aircraft engineering, the design of CMC bolted joint gains paramount attention because of its capacity to to improve load-bearing efficiency of aircraft key structure. In this work, a 3 D finite element model was established to predict tensile performance and failure modes of single-lap, single-bolt 2 D C/SiC composite, and superalloy joint, which considers the progressive damage behavior of 2 D woven C/SiC composites. On the basis of the developed progressive damage model, a parametric study was carried out to illustrate the effects of bolt preload and bolt-hole clearance on mechanical behaviors of the hybrid bolted joint. It was found that the increase in the value of bolt preload made the failure load grow first and then drop, and the optimum value of bolt preload 5.00 kN generated 56.47% rise in the initial failure load and 22.83% rise in the final failure load for the bolted joint in comparison with zero preload case. As the clearance increased from 0 to 2.00%, the initial and final failure loads respectively declined by 45.88% and 24.02% for 2.00% bolt-hole clearance relative to the neat-fit case. The loss in failure loads can be reduced to compressive stress concentration around the fastening hole-edge area, leading to the appearance of earlier damages by the introduction of increasing bolt hole clearance.展开更多
Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide coope...Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide cooperative support to each other to reduce capacity and improve system reliability.A fast power control method for substations is needed due to rapid load changes and low overload capability of the system.This paper proposes a fast power control method based on high-speed communication between substations,with additional transient power control to significantly improve the dynamic response of the system.展开更多
Chlorine-substituted ketones are crucial intermediates in organic synthesis,and acyl chlorination of chemical feedstocks employing commercially available benzoyl chloride provides an atom-and-step economic route for t...Chlorine-substituted ketones are crucial intermediates in organic synthesis,and acyl chlorination of chemical feedstocks employing commercially available benzoyl chloride provides an atom-and-step economic route for their synthesis.While atomtransfer radical addition(ATRA)has proven effective for 1,2-acyl chlorination,the efficient realization of 1,3-acyl chlorination has remained a considerable challenge.In this study,an NHC/photocatalyst dual-catalyzed system was developed to facilitate the 1,3-acyl chlorination of cyclopropanes using benzoyl chloride as a bifunctional reagent.This strategy also enables the synthesis of acyl-cyclopropanes with quaternary carbon centers through a nucleophilic annulation process.The practical utility of this approach was demonstrated through large-scale synthesis,product derivatization,and the preparation of analogs of antipsychotics,including haloperidol,melperone and fluanisone.展开更多
Alkenes are ubiquitous,and the difunctionalization of alkenes represents one of the most practical approaches for the construction of value-added compounds.Dicarbonylation of alkenes provides direct access to value-ad...Alkenes are ubiquitous,and the difunctionalization of alkenes represents one of the most practical approaches for the construction of value-added compounds.Dicarbonylation of alkenes provides direct access to value-added 1,4-dicarbonyl compounds.However,selectivity control for unsymmetric 1,2-dicarbonylation is of great challenge.We herein describe NHCs and photocatalysis co-catalyzed three-component radical 1,2-dicarbonylation of alkenes by distinguishing two carbonyl groups,providing structurally diversified 1,4-diketones.Distinct properties of acyl radical and NHCs-stabilized ketyl radical contributed to selectivity control.Acyl radicals are rapidly added to alkenes delivering alkyl radicals,which undergo subsequent radicalradical cross-coupling with NHCs-stabilized ketyl-type radicals,affording 1,2-dicarbonylation products.This transformation features mild reaction conditions,broad substrate scope,and excellent selectivity,providing a general and practical approach for the dicarbonylation of olefins.展开更多
Secondary alcohols bearing both axial and central chirality comprise attractive biological activity and exhibit excellent chiral induction in asymmetric reactions.However,only very limited asymmetric catalytic approac...Secondary alcohols bearing both axial and central chirality comprise attractive biological activity and exhibit excellent chiral induction in asymmetric reactions.However,only very limited asymmetric catalytic approaches were developed for their synthesis.We herein describe visible light-mediated cobalt-catalyzed asymmetric reductive Grignard-type addition of aryl iodides with axially prochiral biaryl dialdehydes leading to the direct construction of axially chiral secondary alcohols.Preliminary mechanistic studies indicate that efficient kinetic recognition of diastereomers might occur for axially prochiral dialdehydes to improve the stereoselectivity,which might open a new avenue for the challenging cascade construction of multiple chiral elements.This protocol features excellent enantio-and diastereoselectivity,green and mild conditions,simple operation,and broad substrate scope,providing a modular platform for the synthesis of secondary axially chiral alcohols.展开更多
Wild bees are ecologically vital but increasingly threatened by anthropogenic activities,leading to uncertain survival and health outcomes in urban environments.The gut microbiome contains features indicating host hea...Wild bees are ecologically vital but increasingly threatened by anthropogenic activities,leading to uncertain survival and health outcomes in urban environments.The gut microbiome contains features indicating host health and reflecting long-term evolutionary adaptation and acute reactions to real-time stressors.Moving beyond bacteria,we propose a comprehensive analysis integrating diet,bacteriome,virome,resistome,and their association to understand the survival status of urban lives better.We conducted a study on mason bees(Osmia excavata)across 10 urban agricultural sites in Suzhou,China,using shotgun gut metagenome sequencing for data derived from total gut DNA.Our findings revealed that most ingested pollen originated from Brassica crops and the unexpected garden tree Plantanus,indicating that floral resources at the 10 sites supported Osmia but with limited plant diversity.Varied city landscapes revealed site-specific flowers that all contributed to Osmia sustenance.The gut bacterial community,dominated by Gammaproteobacteria,showed remarkable structural stability across 8 sites but suggested perturbations at 2 sites.Antibiotic resistance gene profiles highly varied across 10 sites with prevalent unclassified drug classes,highlighting environmental threats to both bees and humans.The virome analysis identified honeybee pathogens,suggesting potential virus spillover.Many unknown bacteriophages were detected,some of which targeted the core gut bacteria,underscoring their role in maintaining gut homeostasis.These multifaceted metagenomic insights hold the potential to predict bee health and identify environmental threats,thereby guiding probiotic development and city management for effective bee conservation.展开更多
A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel convert...A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel converter (MMC). The FBSM-MMC is a novel type of voltage source converter (VSC) and can directly control the output DC voltage and conduct bipolar currents, thus flexibly controlling the power flow of the urban rail transit catenary. The proposed topology can overcome the inherent disadvantages of the output voltage drop in the diode rectifier units, increase the power supply distance and reduce the number of traction substations. The flexible DC technology can coordinate multiple FBSM-MMCs in a wide area and jointly complete the bidirectional control of catenary power flow during the operation of the electric locomotive, so as to realize the local consumption and optimal utilization of the recovered braking energy of the train. In addition, the FBSM-MMCs can also adjust the output current when the locomotive is out of service to prevent the catenary from icing in winter. The working modes of the proposed topology are illustrated in detail and the control strategy is specially designed for normal locomotive operations and catenary de-icing. Simulation cases conducted by PSCAD/EMTDC validate the proposed topology and its control strategy.展开更多
Hydrogels are promising candidates for mimicking native extracellular matrix(ECM)and are therefore widely adopted as scaffolds in tissue engineering.However,conventional hydrogels composed of static networks are prone...Hydrogels are promising candidates for mimicking native extracellular matrix(ECM)and are therefore widely adopted as scaffolds in tissue engineering.However,conventional hydrogels composed of static networks are prone to permanent structural damages and lack the ability to provide the time-dependent mechanical cues,which are essential for cell development,ECM remodeling,and tissue regeneration.The recent substantial development in the structurally dynamic hydrogels with energy-dissipative ability has demonstrated the unique capability of such viscoelastic hydrogels to withstand extreme biomechanical loads and regulate cellular behaviors not present in classical hydrogels.This review starts with the general design principles for energy-dissipative hydrogels,followed by recent advancements in fabrication approaches for energy-dissipative hydrogels.We then highlight some applications of energy-dissipative hydrogels in tissue engineering,including bone and cartilage regeneration,vessel regeneration,nerve regeneration,and wound healing.Finally,we discuss about the key current challenges and future development of energy-dissipative hydrogels for biomedical applications.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.52275142)Science Center for Gas Turbine Project(Grant Nos.P2022-AIII-003-001,P2022-B-III-005-001)+1 种基金National Science and Technology Major Project(Grant Nos.J2019-IV-0009-0077,Y2022-IV-0002-0019,J2019-IV-0008-0076)National Basic Scientific Research Project(Grant No.JCKY2021601B204)。
文摘Creep is one of the most typical failure modes for the turbine blades of an aero-engine.The microstructure of the turbine blades after long-term service can be adjusted by rejuvenation heat treatment(RHT)to restore its creep properties.In this work,a series of RHT experiments were carried out on a directionally solidified(DS)nickel-based superalloy under different solution temperatures and primary aging temperatures based on the standard heat treatment(SHT)process parameters to investigate the mechanism of temperature influence on DS's microstructure after RHT.It is indicated that a more uniform microstructure can be obtained under higher solution temperatures and lower primary aging temperatures compared to the SHT process.Furthermore,by employing the image processing methods to quantify microstructural parameters,a comprehensive indicator parameter for the RHT effect(marked as Prej)was proposed to characterize the effects of RHT on DS superalloy's microstructure and creep property combined with the entropy weight method.Based on this,a regression model to describe the relationship between RHT process parameters and Prej was constructed by using the response surface methodology(RSM).It is revealed that the optimal solution temperature and primary aging temperature for this DS superalloy are 1283°C and 1095°C,respectively.Then the conclusion was validated through complete creep experiments on the DS superalloy,which showed the creep life after RHT reaches 95.5%of the SHT specimen,and the total life has increased by 20.6%.
基金supported by the Central University Basic Research Business Expenses Special Fund Project[grant number:2572018AA37]the Fundamental Research Funds for the Central Universities[2572019CP01]。
文摘The key transcription factor gene PdP apE RF109 was cloned from Populus davidiana×P.alba var.pyramidalis(Pdpap),and after overexpression of P dP ap ERF109 in transformants,the gene functions in the resistance response to Fusarium oxysporum infection.Compared with the wild Pdpap,after inoculation with F.oxysporum,the physiological and biochemical characteristics,including relative fresh weight,peroxidase activity,and the percentage of electrolyte leakage showed that,after overexpression of the PdPapERF109 gene,the transformants grew well and displayed significant resistance to F.oxysporum infection.By comparing the reactive oxygen species scavenging capacity of Pdpap plants after pathogen infection,the P dPapERF109-overexpressing plants had significantly better reactive oxygen species scavenging ability than the wild plants.Comprehensive analysis of plant morphology and various physiological and biochemical parameters showed that the overexpression of the P dpapERF109 gene significantly improved the resistance of Pdpap plants to F.oxysporum root rot.Therefore,increasing the expression of the homologous ERF109 gene can be an effective strategy to increase disease resistance in hybrid poplars.
基金supported by the National Natural Science Foundation of China(No.11772269).
文摘The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate because of dynamic shear failure and extrusion.A new empirical model was presented to predict the perforation diameter in thin plates impacted by high-velocity cylindrical projectiles.The fitting coefficients resulted in a root-mean-square of 0.0641 and a correlation coefficient of 0.991.The errors between the predicted and the experimental values were less than 7.251%,and less than 4.705%for 93.333%cases of the dataset.The accuracy of the proposed model is much higher than that of Hill's model.Compared with historical equations,the new model is more accurate and can well describe the variations of different parameters with the normalized penetrated hole.The model takes into account the strength of materials,which contributes to the excellent results.This paper could provide important theoretical support for the analysis of the perforation process and its mechanism.
基金Supported by the National Natural Science Foundation of China(61862018)the Subject of the Training Plan for Thousands of Young and Middle-aged Backbone Teachers in Guangxi Colleges and Universities(2020QGRW017)。
文摘Background Data-driven event analysis has gradually become the backbone of modern competitive sports analysis. Competitive sports data analysis tasks increasingly use computer vision and machine-learning models for intelligent data analysis. Existing sports visualization systems focus on the player–team data visualization, which is not intuitive enough for team season win–loss data and game time-series data visualization and neglects the prediction of all-star players. Methods This study used an interactive visualization system designed with parallel aggregated ordered hypergraph dynamic hypergraphs, Calliope visualization data story technology,and i Storyline narrative visualization technology to visualize the regular statistics and game time data of players and teams. NPIPVis includes dynamic hypergraphs of a team’s wins and losses and game plot narrative visualization components. In addition, an integrated learning-based all-star player prediction model, SRR-voting, which starts from the existing minority and majority samples, was proposed using the synthetic minority oversampling technique and Random Under Sampler methods to generate and eliminate samples of a certain size to balance the number of allstar and average players in the datasets. Next, a random forest algorithm was introduced to extract and construct the features of players and combined with the voting integrated model to predict the all-star players, using GridSearch CV, to optimize the hyperparameters of each model in integrated learning and then combined with five-fold cross-validation to improve the generalization ability of the model. Finally, the SHapley Additive ex Planations(SHAP) model was introduced to enhance the interpretability of the model. Results The experimental results of comparing the SRR-voting model with six common models show that the accuracy, F1-score, and recall metrics are significantly improved, which verifies the effectiveness and practicality of the SRR-voting model. Conclusions This study combines data visualization and machine learning to design a National Basketball Association data visualization system to help the general audience visualize game data and predict all-star players;this can also be extended to other sports events or related fields.
基金supported by Natural Science Foundation of Sichuan,China(Grant No.:2024ZDZX0019).
文摘Traditional Chinese medicine(TCM)serves as a treasure trove of ancient knowledge,holding a crucial position in the medical field.However,the exploration of TCM's extensive information has been hindered by challenges related to data standardization,completeness,and accuracy,primarily due to the decen-tralized distribution of TCM resources.To address these issues,we developed a platform for TCM knowledge discovery(TCMKD,https://cbcb.cdutcm.edu.cn/TCMKD/).Seven types of data,including syndromes,formulas,Chinese patent drugs(CPDs),Chinese medicinal materials(CMMs),ingredients,targets,and diseases,were manually proofread and consolidated within TCMKD.To strengthen the integration of TCM with modern medicine,TCMKD employs analytical methods such as TCM data mining,enrichment analysis,and network localization and separation.These tools help elucidate the molecular-level commonalities between TCM and contemporary scientific insights.In addition to its analytical capabilities,a quick question and answer(Q&A)system is also embedded within TCMKD to query the database efficiently,thereby improving the interactivity of the platform.The platform also provides a TCM text annotation tool,offering a simple and efficient method for TCM text mining.Overall,TCMKD not only has the potential to become a pivotal repository for TCM,delving into the pharmaco-logical foundations of TCM treatments,but its flexible embedded tools and algorithms can also be applied to the study of other traditional medical systems,extending beyond just TCM.
基金supported by the National Natural Science Foundation of China(Grant No.11772269)。
文摘Based on the dynamic shock response of the material and structure,the hypervelocity impact processes and mechanisms of long composite rods with axial density/impedance gradients penetration into fourlayer targets were studied through experiments and numerical simulation methods.The propagation law of the shock waves,together with the structural responses of the projectiles and targets,the formation and evolution of the fragment groups formed during the processes and their distributions were described.The damage of each target plate was quantitatively analysed by comparing the results of the experiment and numerical simulation.The results showed that the axial density/impedance gradient projectiles could decrease the impact pressure to a certain extent,and the degree of damage to the target plate decreased layer by layer when the head density/impedance of the projectile was high.When the head density/impedance of the projectile was low,the degree of target damage first increased layer by layer until the projectile was completely eroded and then it decreased.The results can provide a reference for the design and application of long rods with axial composite structure for velocities ranging from 6 to 10 Ma or greater.
基金supported by the National Natural Science Foundation of China(No.51627805).
文摘The loosening of implant due to bacterial infection brings great difficulties to the implantation of bionic titanium devices.In this study,the Zeolitic Imidazolate Framework 8(ZIF-8)and silver ions were added to the surface of titanium alloy to obtain a uniform coating,which has nice biological activity and antibacterial property.The material structure characterizations,such as X-ray diffraction(XRD),scanning electron microscope(SEM),X-ray photoelectron spectroscopy(XPS),proved that titanium is successfully modified with ZIF-8 and silver ions.It has micro-and nano-level characteristics,rough porous morphology,and excellent apatite inducing ability.The water contact angle experiment shows that the addition of ZIF-8 greatly increases the hydrophilicity of material,which provides conditions for the attachment of osteoblasts.The polarization curve obtained from the electrochemical test proves that the addition of ZIF-8 coating improves the corrosion resistance of titanium.The release of silver ion has a strong growth inhibitory effect on E.coli,and exhibits excellent antibacterial properties.Therefore,the preparation of ZIF-8/Ag coatings on 3D printed titanium provides a new option for the development of orthopedic implants.
基金This work was supported by the National Natural Science Foundation of China(No.51976139).
文摘Computational fluid dynamics(CFD)has become the main method for the prediction of the properties of the external wind environment in cities and other urban contexts.A review is presented of the existing literature in terms of boundary conditions,building models,computational domains,computational grids,and turbulence models.Some specific issues,such as the accuracy/computational cost ratio and the exploitation of existing empirical correlations,are also examined.
基金Sponsored by the Pre-Research Foundation of Shenyang Aircraft Design and Research Institute,the Aviation Industry Corporation of China(Grant No.JH20128255)the National Defence Basic Research Program(Grant No.JZ20180032)the Pre-Research Foundation of Equipment Development Department of People’s Republic of China Central Military Commission(Grant No.ZJJSN20200001)。
文摘With the considerable applications of ceramic matrix composites(CMC) in aircraft engineering, the design of CMC bolted joint gains paramount attention because of its capacity to to improve load-bearing efficiency of aircraft key structure. In this work, a 3 D finite element model was established to predict tensile performance and failure modes of single-lap, single-bolt 2 D C/SiC composite, and superalloy joint, which considers the progressive damage behavior of 2 D woven C/SiC composites. On the basis of the developed progressive damage model, a parametric study was carried out to illustrate the effects of bolt preload and bolt-hole clearance on mechanical behaviors of the hybrid bolted joint. It was found that the increase in the value of bolt preload made the failure load grow first and then drop, and the optimum value of bolt preload 5.00 kN generated 56.47% rise in the initial failure load and 22.83% rise in the final failure load for the bolted joint in comparison with zero preload case. As the clearance increased from 0 to 2.00%, the initial and final failure loads respectively declined by 45.88% and 24.02% for 2.00% bolt-hole clearance relative to the neat-fit case. The loss in failure loads can be reduced to compressive stress concentration around the fastening hole-edge area, leading to the appearance of earlier damages by the introduction of increasing bolt hole clearance.
基金supported by the National Natural Science Foundation of China under Grant 52277190the Major Science and Technology Projects of China Railway Electrification Engineering Group Co.,LTD.(20192001148).
文摘Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide cooperative support to each other to reduce capacity and improve system reliability.A fast power control method for substations is needed due to rapid load changes and low overload capability of the system.This paper proposes a fast power control method based on high-speed communication between substations,with additional transient power control to significantly improve the dynamic response of the system.
基金supported by the National Key R&D Program of China(2024YFA1509704)the National Natural Science Foundation of China(22471034,22193012,22201033)+1 种基金the Natural Science Foundation of Jilin Province(20230101047JC,YDZJ202201ZYTS338)the Fundamental Research Funds for the Central Universities。
文摘Chlorine-substituted ketones are crucial intermediates in organic synthesis,and acyl chlorination of chemical feedstocks employing commercially available benzoyl chloride provides an atom-and-step economic route for their synthesis.While atomtransfer radical addition(ATRA)has proven effective for 1,2-acyl chlorination,the efficient realization of 1,3-acyl chlorination has remained a considerable challenge.In this study,an NHC/photocatalyst dual-catalyzed system was developed to facilitate the 1,3-acyl chlorination of cyclopropanes using benzoyl chloride as a bifunctional reagent.This strategy also enables the synthesis of acyl-cyclopropanes with quaternary carbon centers through a nucleophilic annulation process.The practical utility of this approach was demonstrated through large-scale synthesis,product derivatization,and the preparation of analogs of antipsychotics,including haloperidol,melperone and fluanisone.
基金supported by the National Natural Science Foundation of China (22001157,21831002,22193012)the Ten Thousand Talents Program+2 种基金the Fundamental Research Funds for the Central Universities (2412022QD016,2412021QD007)the Natural Science Foundation of Jilin Province (YDZJ202201ZYTS338)the Natural Science Foundation of Shaanxi Province (2020JQ-404)
文摘Alkenes are ubiquitous,and the difunctionalization of alkenes represents one of the most practical approaches for the construction of value-added compounds.Dicarbonylation of alkenes provides direct access to value-added 1,4-dicarbonyl compounds.However,selectivity control for unsymmetric 1,2-dicarbonylation is of great challenge.We herein describe NHCs and photocatalysis co-catalyzed three-component radical 1,2-dicarbonylation of alkenes by distinguishing two carbonyl groups,providing structurally diversified 1,4-diketones.Distinct properties of acyl radical and NHCs-stabilized ketyl radical contributed to selectivity control.Acyl radicals are rapidly added to alkenes delivering alkyl radicals,which undergo subsequent radicalradical cross-coupling with NHCs-stabilized ketyl-type radicals,affording 1,2-dicarbonylation products.This transformation features mild reaction conditions,broad substrate scope,and excellent selectivity,providing a general and practical approach for the dicarbonylation of olefins.
基金Natural Science Foundation of Jilin Province(20230101047JC,YDZJ202201ZYTS338)NSFC(22001157,21831002,22193012,and 22201033)+1 种基金Jilin Educational Committee(JJKH20231295KJ,JJKH20231302KJ)the Fundamental Research Funds for the Central Universities(2412022ZD012,2412022QD016,2412021QD007)for generous financial support.
文摘Secondary alcohols bearing both axial and central chirality comprise attractive biological activity and exhibit excellent chiral induction in asymmetric reactions.However,only very limited asymmetric catalytic approaches were developed for their synthesis.We herein describe visible light-mediated cobalt-catalyzed asymmetric reductive Grignard-type addition of aryl iodides with axially prochiral biaryl dialdehydes leading to the direct construction of axially chiral secondary alcohols.Preliminary mechanistic studies indicate that efficient kinetic recognition of diastereomers might occur for axially prochiral dialdehydes to improve the stereoselectivity,which might open a new avenue for the challenging cascade construction of multiple chiral elements.This protocol features excellent enantio-and diastereoselectivity,green and mild conditions,simple operation,and broad substrate scope,providing a modular platform for the synthesis of secondary axially chiral alcohols.
基金supported by the Research Development Fund(RDF-23-01-067)the Summer Undergraduate Research Fellowship(SURF)Program(SURF-2023-0079)from Xi'an Jiaotong-Liverpool University to M.T.
文摘Wild bees are ecologically vital but increasingly threatened by anthropogenic activities,leading to uncertain survival and health outcomes in urban environments.The gut microbiome contains features indicating host health and reflecting long-term evolutionary adaptation and acute reactions to real-time stressors.Moving beyond bacteria,we propose a comprehensive analysis integrating diet,bacteriome,virome,resistome,and their association to understand the survival status of urban lives better.We conducted a study on mason bees(Osmia excavata)across 10 urban agricultural sites in Suzhou,China,using shotgun gut metagenome sequencing for data derived from total gut DNA.Our findings revealed that most ingested pollen originated from Brassica crops and the unexpected garden tree Plantanus,indicating that floral resources at the 10 sites supported Osmia but with limited plant diversity.Varied city landscapes revealed site-specific flowers that all contributed to Osmia sustenance.The gut bacterial community,dominated by Gammaproteobacteria,showed remarkable structural stability across 8 sites but suggested perturbations at 2 sites.Antibiotic resistance gene profiles highly varied across 10 sites with prevalent unclassified drug classes,highlighting environmental threats to both bees and humans.The virome analysis identified honeybee pathogens,suggesting potential virus spillover.Many unknown bacteriophages were detected,some of which targeted the core gut bacteria,underscoring their role in maintaining gut homeostasis.These multifaceted metagenomic insights hold the potential to predict bee health and identify environmental threats,thereby guiding probiotic development and city management for effective bee conservation.
基金supported in part by National Key Research and Development Program of China(2017YFB1200801)Continuous Co-phase Traction Power System based on Static Power Converter(20192001148).
文摘A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel converter (MMC). The FBSM-MMC is a novel type of voltage source converter (VSC) and can directly control the output DC voltage and conduct bipolar currents, thus flexibly controlling the power flow of the urban rail transit catenary. The proposed topology can overcome the inherent disadvantages of the output voltage drop in the diode rectifier units, increase the power supply distance and reduce the number of traction substations. The flexible DC technology can coordinate multiple FBSM-MMCs in a wide area and jointly complete the bidirectional control of catenary power flow during the operation of the electric locomotive, so as to realize the local consumption and optimal utilization of the recovered braking energy of the train. In addition, the FBSM-MMCs can also adjust the output current when the locomotive is out of service to prevent the catenary from icing in winter. The working modes of the proposed topology are illustrated in detail and the control strategy is specially designed for normal locomotive operations and catenary de-icing. Simulation cases conducted by PSCAD/EMTDC validate the proposed topology and its control strategy.
基金This work was supported by the National Key R&D Program of China(2022YFB380440003)the National Natural Science Foundation of China(32271385).
文摘Hydrogels are promising candidates for mimicking native extracellular matrix(ECM)and are therefore widely adopted as scaffolds in tissue engineering.However,conventional hydrogels composed of static networks are prone to permanent structural damages and lack the ability to provide the time-dependent mechanical cues,which are essential for cell development,ECM remodeling,and tissue regeneration.The recent substantial development in the structurally dynamic hydrogels with energy-dissipative ability has demonstrated the unique capability of such viscoelastic hydrogels to withstand extreme biomechanical loads and regulate cellular behaviors not present in classical hydrogels.This review starts with the general design principles for energy-dissipative hydrogels,followed by recent advancements in fabrication approaches for energy-dissipative hydrogels.We then highlight some applications of energy-dissipative hydrogels in tissue engineering,including bone and cartilage regeneration,vessel regeneration,nerve regeneration,and wound healing.Finally,we discuss about the key current challenges and future development of energy-dissipative hydrogels for biomedical applications.
