Energy for space vehicles in low Earth orbit(LEO) is mainly generated by solar arrays, and the service time of the vehicles is controlled by the lifetime of these arrays, which depends mainly on the lifetime of the in...Energy for space vehicles in low Earth orbit(LEO) is mainly generated by solar arrays, and the service time of the vehicles is controlled by the lifetime of these arrays, which depends mainly on the lifetime of the interconnects. To increase the service life of LEO satellites, molybdenum/platinum/silver(Mo/Pt/Ag) laminated metal matrix composite(LMMC) interconnectors are widely used in place of Mo/Ag LMMC and Ag interconnectors in solar arrays. A 2D thermal-electrical-mechanical coupled axisymmetric model was established to simulate the behavior of the parallel gap resistance welding(PGRW) process for solar cells and Mo/Pt/Ag composite interconnectors using the commercial software ANSYS. The direct multicoupled PLANE223 element and the contact pair elements TARGE169 and CONTA172 were employed. A transitional meshing method was applied to solve the meshing problem due to the ultrathin(1 μm) intermediate Pt layer. A comparison of the analysis results with the experimental results revealed that the best parameters were 60 W, 60 ms, and 0.0138 MPa. The voltage and current predicted by the finite element method agreed well with the experimental results. This study contributes to a further understanding of the mechanism of PGRW and provides guidance for finite element simulation of the process of welding with an ultrathin interlayer.展开更多
Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology...Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology optimization simulations based on a projectile perforation model,and a new topologic projectile is obtained.Then two types of 316L stainless steel projectiles(the solid and the topology)are printed in a selective laser melt(SLM)machine to evaluate the penetration performance of the projectiles by the ballistic test.The experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles,indicating the better penetration ability of the topologic projectiles.Finally,microscopic studies(scanning electron microscope and X-ray micro-CT)are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic projectiles.An explicit dynamics simulation was also performed,and the failure locations of the residual topologic projectiles were in good agreement with the experimental results,which can better guide the design of new projectiles combining AM and topology optimization in the future.展开更多
With the proliferation of the Internet of Things(IoT),various services are emerging with totally different features and requirements,which cannot be supported by the current fifth generation of mobile cellular network...With the proliferation of the Internet of Things(IoT),various services are emerging with totally different features and requirements,which cannot be supported by the current fifth generation of mobile cellular networks(5G).The future sixth generation of mobile cellular networks(6G)is expected to have the capability to support new and unknown services with changing requirements.Hence,in addition to enhancing its capability by 10–100 times compared with 5G,6G should also be intelligent and open to adapt to the ever-changing services in the IoT,which requires a convergence of Communication,Computing and Caching(3C).Based on the analysis of the requirements of new services for 6G,this paper identifies key enabling technologies for an intelligent and open 6G network,all featured with 3C convergence.These technologies cover fundamental and emerging topics,including 3C-based spectrum management,radio channel construction,delay-aware transmission,wireless distributed computing,and network self-evolution.From the detailed analysis of these 3C-based technologies presented in this paper,we can see that although they are promising to enable an intelligent and open 6G,more efforts are needed to realize the expected 6G network.展开更多
In this study, an innovative approach was used to fabricate Ti–Ta composite biomaterials through cold spray additive manufacturing followed by a diff usion treatment. The microstructure and mechanical properties of t...In this study, an innovative approach was used to fabricate Ti–Ta composite biomaterials through cold spray additive manufacturing followed by a diff usion treatment. The microstructure and mechanical properties of the composites were investigated in detail using field emission scanning electron microscopy, electron backscatter diff raction, 3D X-ray computed tomography, tensile test, nanohardness test and resonance vibration test. The obtained results indicated that the prepared composites have inhomogeneity in their microstructure and composition. A unique microstructure, composed of Ti-rich, Ta-rich and diff usion regions, was evolved in the composites due to incomplete diff usion between Ti and Ta splats. Further, Kirkendall pores were formed in the composites due to uneven diff usion of the two phases(of Ti and Ta) during high-temperature heat treatment. The prepared composites simultaneously showed low elastic modulus and high tensile strength which is required for a good biomaterial. Low elastic modulus was associated with the residual pores and the alloying eff ect of Ta in Ti, while high tensile strength was related to the solid solution strengthening eff ects. The obtained results indicated that the prepared Ti–Ta composites have a great potential to become a new candidate for biomedical applications.展开更多
We propose an effective scheme of the deep learning method for high-order nonlinear soliton equations and explore the influence of activation functions on the calculation results for higherorder nonlinear soliton equa...We propose an effective scheme of the deep learning method for high-order nonlinear soliton equations and explore the influence of activation functions on the calculation results for higherorder nonlinear soliton equations. The physics-informed neural networks approximate the solution of the equation under the conditions of differential operator, initial condition and boundary condition. We apply this method to high-order nonlinear soliton equations, and verify its efficiency by solving the fourth-order Boussinesq equation and the fifth-order Korteweg–de Vries equation. The results show that the deep learning method can be used to solve high-order nonlinear soliton equations and reveal the interaction between solitons.展开更多
Inflammation is a driving force of hematopoietic stem cells(HSCs)aging,causing irreversible exhaustion of functional HSCs.However,the underlying mechanism of HSCs erosion by inflammatory insult remains poorly understo...Inflammation is a driving force of hematopoietic stem cells(HSCs)aging,causing irreversible exhaustion of functional HSCs.However,the underlying mechanism of HSCs erosion by inflammatory insult remains poorly understood.Here,we find that transient LPS exposure primes aged HSCs to undergo accelerated differentiation at the expense of self-renewal,leading to depletion of HSCs.Meanwhile,the central regulator nuclear factor kappa B(NF-κB)mediating functional impairment by inflammation insult induces differential transcriptional response in aged HSCs compared with young HSCs,with precocious activation of myeloid lineage genes.Altered compartmentalization and chromatin loop formation are associated with aging-related differential transcriptional response in HSCs upon lipopolysaccharide(LPS)stimulation.Mechanistically,enhancer and promoter regions of myeloid lineage genes in aged HSCs are more accessible and display more rapid and prominent CTCF occupancy upon LPS stimulation.Our study provides comprehensive resources for the three-dimensional(3D)genome structure of HSCs and sheds light into the ordered genome organization and the associated transcriptome signature underlying HSCs aging.展开更多
The TET family is well known for active DNA demethylation and plays important roles in regulating transcription,the epigenome and development.Nevertheless,previous studies using knockdown(KD)or knockout(KO)models to i...The TET family is well known for active DNA demethylation and plays important roles in regulating transcription,the epigenome and development.Nevertheless,previous studies using knockdown(KD)or knockout(KO)models to investigate the function of TET have faced challenges in distinguishing its enzymatic and nonenzymatic roles,as well as compensatory effects among TET family members,which has made the understanding of the enzymatic role of TET not accurate enough.To solve this problem,we successfully generated mice catalytically inactive for specific Tet members(Tetm/m).We observed that,compared with the reported KO mice,mutant mice exhibited distinct developmental defects,including growth retardation,sex imbalance,infertility,and perinatal lethality.Notably,Tetm/mmouse embryonic stem cells(mESCs)were successfully established but entered an impaired developmental program,demonstrating extended pluripotency and defects in ectodermal differentiation caused by abnormal DNA methylation.Intriguingly,Tet3,traditionally considered less critical for m ESCs due to its lower expression level,had a significant impact on the global hydroxymethylation,gene expression,and differentiation potential of mESCs.Notably,there were common regulatory regions between Tet1 and Tet3 in pluripotency regulation.In summary,our study provides a more accurate reference for the functional mechanism of Tet hydroxymethylase activity in mouse development and ESC pluripotency regulation.展开更多
Dear Editor,Since the COVID-19 pandemic, the potential risks associated with maternal SARS-CoV-2 infection and its effect on fetal development have been a subject of considerable public concern. Previous studies have ...Dear Editor,Since the COVID-19 pandemic, the potential risks associated with maternal SARS-CoV-2 infection and its effect on fetal development have been a subject of considerable public concern. Previous studies have shown that SARS-CoV-2 infection during pregnancy may increase the incidence of adverse outcomes.展开更多
The development and maturation of follicles is a sophisticated and multistage process.The dynamic gene expression of oocytes and their surrounding somatic cells and the dialogs between these cells are critical to this...The development and maturation of follicles is a sophisticated and multistage process.The dynamic gene expression of oocytes and their surrounding somatic cells and the dialogs between these cells are critical to this process.In this study,we accurately classified the oocyte and follicle development into nine stages and profiled the gene expression of mouse oocytes and their surrounding granulosa cells and cumulus cells.The clustering of the transcriptomes showed the trajectories of two distinct development courses of oocytes and their surrounding somatic cells.Gene expression changes precipitously increased at Type 4 stage and drastically dropped afterward within both oocytes and granulosa cells.Moreover,the number of differentially expressed genes between oocytes and granulosa cells dramatically increased at Type 4 stage,most of which persistently passed on to the later stages.Strikingly,cell communications within and between oocytes and granulosa cells became active from Type 4 stage onward.Cell dialogs connected oocytes and granulosa cells in both unidirectional and bidirectional manners.TGFB2/3,TGFBR2/3,INHBA/B,and ACVR1/1B/2B of TGF-βsignaling pathway functioned in the follicle development.NOTCH signaling pathway regulated the development of granulosa cells.Additionally,many maternally DNA methylation-or H3K27me3-imprinted genes remained active in granulosa cells but silent in oocytes during oogenesis.Collectively,Type 4 stage is the key turning point when significant transcription changes diverge the fate of oocytes and granulosa cells,and the cell dialogs become active to assure follicle development.These findings shed new insights on the transcriptome dynamics and cell dialogs facilitating the development and maturation of oocytes and follicles.展开更多
基金supported by the National Key Research and Development Program of China(Nos. 2018YFB0703904 and 2017YFE0302600)。
文摘Energy for space vehicles in low Earth orbit(LEO) is mainly generated by solar arrays, and the service time of the vehicles is controlled by the lifetime of these arrays, which depends mainly on the lifetime of the interconnects. To increase the service life of LEO satellites, molybdenum/platinum/silver(Mo/Pt/Ag) laminated metal matrix composite(LMMC) interconnectors are widely used in place of Mo/Ag LMMC and Ag interconnectors in solar arrays. A 2D thermal-electrical-mechanical coupled axisymmetric model was established to simulate the behavior of the parallel gap resistance welding(PGRW) process for solar cells and Mo/Pt/Ag composite interconnectors using the commercial software ANSYS. The direct multicoupled PLANE223 element and the contact pair elements TARGE169 and CONTA172 were employed. A transitional meshing method was applied to solve the meshing problem due to the ultrathin(1 μm) intermediate Pt layer. A comparison of the analysis results with the experimental results revealed that the best parameters were 60 W, 60 ms, and 0.0138 MPa. The voltage and current predicted by the finite element method agreed well with the experimental results. This study contributes to a further understanding of the mechanism of PGRW and provides guidance for finite element simulation of the process of welding with an ultrathin interlayer.
基金sponsored by the National Key Research and Development Program of China[Grant Nos.2020YFC0826804 and 2022YFC3320504]the National Natural Science Foundation of China[Grant No.11772059]。
文摘Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology optimization simulations based on a projectile perforation model,and a new topologic projectile is obtained.Then two types of 316L stainless steel projectiles(the solid and the topology)are printed in a selective laser melt(SLM)machine to evaluate the penetration performance of the projectiles by the ballistic test.The experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles,indicating the better penetration ability of the topologic projectiles.Finally,microscopic studies(scanning electron microscope and X-ray micro-CT)are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic projectiles.An explicit dynamics simulation was also performed,and the failure locations of the residual topologic projectiles were in good agreement with the experimental results,which can better guide the design of new projectiles combining AM and topology optimization in the future.
基金This work is supported by the National Natural Science Youth Fund of China granted by No.61901452 and Innovative Project of ICT/CAS granted by No.20196110
文摘With the proliferation of the Internet of Things(IoT),various services are emerging with totally different features and requirements,which cannot be supported by the current fifth generation of mobile cellular networks(5G).The future sixth generation of mobile cellular networks(6G)is expected to have the capability to support new and unknown services with changing requirements.Hence,in addition to enhancing its capability by 10–100 times compared with 5G,6G should also be intelligent and open to adapt to the ever-changing services in the IoT,which requires a convergence of Communication,Computing and Caching(3C).Based on the analysis of the requirements of new services for 6G,this paper identifies key enabling technologies for an intelligent and open 6G network,all featured with 3C convergence.These technologies cover fundamental and emerging topics,including 3C-based spectrum management,radio channel construction,delay-aware transmission,wireless distributed computing,and network self-evolution.From the detailed analysis of these 3C-based technologies presented in this paper,we can see that although they are promising to enable an intelligent and open 6G,more efforts are needed to realize the expected 6G network.
文摘In this study, an innovative approach was used to fabricate Ti–Ta composite biomaterials through cold spray additive manufacturing followed by a diff usion treatment. The microstructure and mechanical properties of the composites were investigated in detail using field emission scanning electron microscopy, electron backscatter diff raction, 3D X-ray computed tomography, tensile test, nanohardness test and resonance vibration test. The obtained results indicated that the prepared composites have inhomogeneity in their microstructure and composition. A unique microstructure, composed of Ti-rich, Ta-rich and diff usion regions, was evolved in the composites due to incomplete diff usion between Ti and Ta splats. Further, Kirkendall pores were formed in the composites due to uneven diff usion of the two phases(of Ti and Ta) during high-temperature heat treatment. The prepared composites simultaneously showed low elastic modulus and high tensile strength which is required for a good biomaterial. Low elastic modulus was associated with the residual pores and the alloying eff ect of Ta in Ti, while high tensile strength was related to the solid solution strengthening eff ects. The obtained results indicated that the prepared Ti–Ta composites have a great potential to become a new candidate for biomedical applications.
基金supported by National Science Foundation of China(52171251)Liao Ning Revitalization Talents Program(XLYC1907014)+2 种基金the Fundamental Research Funds for the Central Universities(DUT21ZD205)Ministry of Industry and Information Technology(2019-357)the Project of State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,MNR(QNHX2112)。
文摘We propose an effective scheme of the deep learning method for high-order nonlinear soliton equations and explore the influence of activation functions on the calculation results for higherorder nonlinear soliton equations. The physics-informed neural networks approximate the solution of the equation under the conditions of differential operator, initial condition and boundary condition. We apply this method to high-order nonlinear soliton equations, and verify its efficiency by solving the fourth-order Boussinesq equation and the fifth-order Korteweg–de Vries equation. The results show that the deep learning method can be used to solve high-order nonlinear soliton equations and reveal the interaction between solitons.
基金supported by the National Natural Science Foundation of China (32122030, 32470845, 32330030, 92168205, 92049304, 82030039, 32341004, 82230047, 32122030, 31721003, 32000562, 32170589, 31970758, 31972882, and 92049112)the Ministry of Science and Technology of China (2024YFA1107000, 2022YFC2702200, 2021YFC2700301, 2021YFA1100103, 2021YFA1100302, 2024YFA098701)+5 种基金the Science and Technology Innovation Action Plan of the Science and Technology Commission of Shanghai Municipality (21JC1405500)the innovation team project of universities in Guangdong province (2023KCXTD004)Shanghai Rising-Star Program (A type) of the Science, Technology Commission of Shanghai Municipality (21QA1409500)the Fundamental Research Funds for the Central Universities (22120240435)the Peak Disciplines (Type Ⅳ) of Institutions of Higher Learning in Shanghaithe Guangdong Basic and Applied Basic Research Foundation (2022A1515011204)
文摘Inflammation is a driving force of hematopoietic stem cells(HSCs)aging,causing irreversible exhaustion of functional HSCs.However,the underlying mechanism of HSCs erosion by inflammatory insult remains poorly understood.Here,we find that transient LPS exposure primes aged HSCs to undergo accelerated differentiation at the expense of self-renewal,leading to depletion of HSCs.Meanwhile,the central regulator nuclear factor kappa B(NF-κB)mediating functional impairment by inflammation insult induces differential transcriptional response in aged HSCs compared with young HSCs,with precocious activation of myeloid lineage genes.Altered compartmentalization and chromatin loop formation are associated with aging-related differential transcriptional response in HSCs upon lipopolysaccharide(LPS)stimulation.Mechanistically,enhancer and promoter regions of myeloid lineage genes in aged HSCs are more accessible and display more rapid and prominent CTCF occupancy upon LPS stimulation.Our study provides comprehensive resources for the three-dimensional(3D)genome structure of HSCs and sheds light into the ordered genome organization and the associated transcriptome signature underlying HSCs aging.
基金supported by the National Key Research and Development Program of China(2020YFA0112500,2021YFA1100300,2021YFC2700300 and 2022YFC2702200)supported by the Fundamental Research Funds for the Central Universities+2 种基金National Natural Science Foundation of China(32070857 and 32270856,and 32270858)the Science and Technology Commission of Shanghai Municipality(23JC1403700)Peak Disciplines(TypeⅣ)of Institutions of Higher Learning in Shanghai。
文摘The TET family is well known for active DNA demethylation and plays important roles in regulating transcription,the epigenome and development.Nevertheless,previous studies using knockdown(KD)or knockout(KO)models to investigate the function of TET have faced challenges in distinguishing its enzymatic and nonenzymatic roles,as well as compensatory effects among TET family members,which has made the understanding of the enzymatic role of TET not accurate enough.To solve this problem,we successfully generated mice catalytically inactive for specific Tet members(Tetm/m).We observed that,compared with the reported KO mice,mutant mice exhibited distinct developmental defects,including growth retardation,sex imbalance,infertility,and perinatal lethality.Notably,Tetm/mmouse embryonic stem cells(mESCs)were successfully established but entered an impaired developmental program,demonstrating extended pluripotency and defects in ectodermal differentiation caused by abnormal DNA methylation.Intriguingly,Tet3,traditionally considered less critical for m ESCs due to its lower expression level,had a significant impact on the global hydroxymethylation,gene expression,and differentiation potential of mESCs.Notably,there were common regulatory regions between Tet1 and Tet3 in pluripotency regulation.In summary,our study provides a more accurate reference for the functional mechanism of Tet hydroxymethylase activity in mouse development and ESC pluripotency regulation.
基金supported by the Chinese National Program on the Key Basic Research Project(2021YFA1100300,2020YFA0112500)the National Natural Science Foundation of China(31721003,31820103009,32270856,32070857,32270858)。
文摘Dear Editor,Since the COVID-19 pandemic, the potential risks associated with maternal SARS-CoV-2 infection and its effect on fetal development have been a subject of considerable public concern. Previous studies have shown that SARS-CoV-2 infection during pregnancy may increase the incidence of adverse outcomes.
基金supported by the National Key R&D Program of China(Grant Nos.2019YFA0110000 and 2021YFA1100300)the National Natural Science Foundation of China(Grant Nos.31972882,31721003,31771419,and 31900621)the Natural Science Foundation of Shanghai Municipality,China(Grant No.21ZR1465500)。
文摘The development and maturation of follicles is a sophisticated and multistage process.The dynamic gene expression of oocytes and their surrounding somatic cells and the dialogs between these cells are critical to this process.In this study,we accurately classified the oocyte and follicle development into nine stages and profiled the gene expression of mouse oocytes and their surrounding granulosa cells and cumulus cells.The clustering of the transcriptomes showed the trajectories of two distinct development courses of oocytes and their surrounding somatic cells.Gene expression changes precipitously increased at Type 4 stage and drastically dropped afterward within both oocytes and granulosa cells.Moreover,the number of differentially expressed genes between oocytes and granulosa cells dramatically increased at Type 4 stage,most of which persistently passed on to the later stages.Strikingly,cell communications within and between oocytes and granulosa cells became active from Type 4 stage onward.Cell dialogs connected oocytes and granulosa cells in both unidirectional and bidirectional manners.TGFB2/3,TGFBR2/3,INHBA/B,and ACVR1/1B/2B of TGF-βsignaling pathway functioned in the follicle development.NOTCH signaling pathway regulated the development of granulosa cells.Additionally,many maternally DNA methylation-or H3K27me3-imprinted genes remained active in granulosa cells but silent in oocytes during oogenesis.Collectively,Type 4 stage is the key turning point when significant transcription changes diverge the fate of oocytes and granulosa cells,and the cell dialogs become active to assure follicle development.These findings shed new insights on the transcriptome dynamics and cell dialogs facilitating the development and maturation of oocytes and follicles.
