随着核仪控系统的复杂性、集成度和数据量的不断增加,传统的控制器局域网络(Controller Area Network,CAN)或外围设备互连(Peripheral Component Interconnect,PCI)等数据总线在一定程度上已难以满足数据快速传输需求。本文基于美国Xil...随着核仪控系统的复杂性、集成度和数据量的不断增加,传统的控制器局域网络(Controller Area Network,CAN)或外围设备互连(Peripheral Component Interconnect,PCI)等数据总线在一定程度上已难以满足数据快速传输需求。本文基于美国Xilinx公司Zynq-7000型片上系统(System on Chip,SoC)设计和实现了基于用户数据报协议(User Datagram Protocol,UDP)的千兆以太网传输系统。首先,对UDP千兆以太网传输系统的实现方式进行了详细描述;然后,采用仿真工具ModelSim对系统方案可行性进行了仿真验证;最后,基于Xilinx的开发板ZC706对系统方案进行了具体实现和功能性能验证。验证结果表明:UDP传输速度最高可以达870 Mbps,能够满足绝大多数核仪控系统的实际传输需求。展开更多
The settlement of the Tibetan Plateau epitomizes human adaptation to a high-altitude environment that poses great challenges to human activity.Here,we reconstruct a 4000-year maternal genetic history of Tibetans using...The settlement of the Tibetan Plateau epitomizes human adaptation to a high-altitude environment that poses great challenges to human activity.Here,we reconstruct a 4000-year maternal genetic history of Tibetans using 128 ancient mitochondrial genome data from 37 sites in Tibet.The phylogeny of haplotypes M9a1a,M9a1b,D4g2,G2a’c,and D4i show that ancient Tibetans share the most recent common ancestor with ancient Middle and Upper Yellow River populations around the Early and Middle Holocene.In addition,the connections between Tibetans and Northeastern Asians vary over the past 4000 years,with a stronger matrilineal connection between the two during 4000 BPe3000 BP,and a weakened connection after 3000 BP,that are coincident with climate change,followed by a reinforced connection after the Tubo period(1400 BPe1100 BP).Besides,an over 4000-year matrilineal continuity is observed in some of the maternal lineages.We also find the maternal genetic structure of ancient Tibetans is correlated to the geography and interactions between ancient Tibetans and ancient Nepal and Pakistan populations.Overall,the maternal genetic history of Tibetans can be characterized as a long-term matrilineal continuity with frequent internal and external population interactions that are dynamically shaped by geography,climate changes,as well as historical events.展开更多
A novel AlCoCrFeNi2.1 eutectic high entropy alloy(EHEA)composite doped with SiC particles was designed and fabricated by laser powder bed fusion(LPBF).Its microstructure characteristic,tensile properties,and metallurg...A novel AlCoCrFeNi2.1 eutectic high entropy alloy(EHEA)composite doped with SiC particles was designed and fabricated by laser powder bed fusion(LPBF).Its microstructure characteristic,tensile properties,and metallurgical defects,with an emphasis on cracking behavior,have been investigated.The results showed that the addition of SiC particles into the AlCoCrFeNi_(2.1)matrix enabled the development of a{100}texture and highly elongated columnar grains,which were the main contributors to mechanical behavior anisotropy.The ultimate tensile strength of 1466±26 MPa and elongation of 9%±3%achieved in the as-deposited EHEA composite surpassed those of advanced metal alloys subjected to additive manufacturing processes.Unfortunately,severe horizontal and longitudinal cracks,as well as a few micro-cracks were observed in the as-deposited bulk samples.Micro-cracks were verified to be associated with the aggregation of carbon and oxide particles.They formed in the final stage of solidification owing to insufficient liquid feeding ability and solidification contraction.The formation of macroscopic cracking was induced by the tensile stress accumulations at sample edges,and the stress concentration areas where microcracks and pores were located were the predominant propagation location.This work provides guidelines for defect control in SiC-reinforced EHEA,assisting in the high-performance design and integrated manufacturing of EHEA composite components.展开更多
Melatonin and abscisic acid,as major plant hormones,play important roles in the physiological and biochemical activities of crops,but the interaction between the two under salt stress is not yet clear.This study inves...Melatonin and abscisic acid,as major plant hormones,play important roles in the physiological and biochemical activities of crops,but the interaction between the two under salt stress is not yet clear.This study investigated the endogenous levels of melatonin and abscisic acid in rice by using exogenous melatonin,abscisic acid,and their synthetic inhibitors,and examined their interactions under salt stress.The research results indicate that melatonin and abscisic acid can improve rice salt tolerance.Melatonin alleviated the salt sensitivity caused by abscisic acid deficiency,increased antioxidant enzyme activity and antioxidant content in rice treated with abscisic acid synth-esis inhibitors,and reduced total reactive oxygen species content and thiobarbituric acid reactive substance accu-mulation.Melatonin also increased the activity of key photosynthetic enzymes and the content of photosynthetic pigments,maintaining the parameters of photosynthetic gas exchange and chlorophyllfluorescence.In summary,melatonin alleviated the effects of abscisic acid deficiency on photosynthesis and antioxidant systems in rice and improved salt tolerance.This study is beneficial for expanding the understanding of melatonin regulation of crop salt tolerance.展开更多
In this study, two-dimensional MXene (Ti3 C2 Tx ) was employed to modify the interface of carbon fiber-reinforced polyetherketoneketone (CF/PEKK) composites, in order to simultaneously improve the electromagnetic inte...In this study, two-dimensional MXene (Ti3 C2 Tx ) was employed to modify the interface of carbon fiber-reinforced polyetherketoneketone (CF/PEKK) composites, in order to simultaneously improve the electromagnetic interference (EMI) shielding performances and mechanical properties. The obtained CF/PEKK composites possessed outstanding EMI and mechanical performances, as anticipated. Specifically, the CF/PEKK composites modified with MXene at 1 mg mL–1 exhibited an excellent EMI shielding effectiveness of 65.2 dB in the X-band, a 103.1% enhancement compared with the unmodified CF/PEKK composites. The attractive EMI shielding performances of CF/PEKK composites originated from enhanced ohmic losses and multiple reflections of electromagnetic waves with the help of the MXene and CF layers. In addition, CF/PEKK composites achieved the best mechanical properties by optimizing the dispersion concentration of MXene to 0.1 mg mL–1 . The flexural strength, flexural modulus, and interlaminar shear strength of CF/PEKK composites reached 1127 MPa, 81 GPa, and 89 MPa, which were 28.5%, 9.5%, and 29.7% higher than that of the unmodified CF/PEKK composites, respectively. Such improvement in mechanical properties could be ascribed to the comprehensive effect of mechanical interlocking, hydrogen bonds, and Van der Waals forces between the introduced MXene and CF, PEKK, respectively.展开更多
By combination of the transient Raman spectroscopic measurement and the density functional theoretical calculations,the structural evolution and stability of TATB under shock compression was investigated.Due to the im...By combination of the transient Raman spectroscopic measurement and the density functional theoretical calculations,the structural evolution and stability of TATB under shock compression was investigated.Due to the improvement in synchronization control between two-stage light gas gun and the transient Raman spectra acquisition,as well as the sample preparation,the Raman peak of the N-O mode of TATB was firstly observed under shock pressure up to 13.6 GPa,noticeably higher than the upper limit of 8.5 GPa reported in available literatures.By taking into account of the continuous shift of the main peak and other observed Raman peaks,we did not distinguish any structural transition or any new species.Moreover,both the present Raman spectra and the time-resolved radiation of TATB during shock loading showed that TATB exhibits higher chemical stability than previous declaration.To reveal the detailed structural response and evolution of TATB under compression,the density functional theoretical calculations were conducted,and it was found that the pressure make N-O bond lengths shorter,nitro bond angles larger,and intermolecular and intra-molecular hydrogen bond interactions enhanced.The observed red shift of Raman peak was ascribed to the abnormal enhancement of H-bound effect on the scissor vibration mode of the nitro group.展开更多
文摘随着核仪控系统的复杂性、集成度和数据量的不断增加,传统的控制器局域网络(Controller Area Network,CAN)或外围设备互连(Peripheral Component Interconnect,PCI)等数据总线在一定程度上已难以满足数据快速传输需求。本文基于美国Xilinx公司Zynq-7000型片上系统(System on Chip,SoC)设计和实现了基于用户数据报协议(User Datagram Protocol,UDP)的千兆以太网传输系统。首先,对UDP千兆以太网传输系统的实现方式进行了详细描述;然后,采用仿真工具ModelSim对系统方案可行性进行了仿真验证;最后,基于Xilinx的开发板ZC706对系统方案进行了具体实现和功能性能验证。验证结果表明:UDP传输速度最高可以达870 Mbps,能够满足绝大多数核仪控系统的实际传输需求。
基金supported by the National Key R&D Program of China(2021YFC1523600)the Chinese Academy of Sciences(CAS)(YSBR-019 and XDB26000000)+3 种基金the National Natural Science Foundation of China(41925009)“Research on the roots of Chinese civilization”of Zhengzhou University(XKZDJC202006)the Tencent Foundation(through the XPLORER PRIZE),and the Howard Hughes Medical Institute(55008731)X.W.was supported by Key National Social Science Foundation of China(16ZDA144).
文摘The settlement of the Tibetan Plateau epitomizes human adaptation to a high-altitude environment that poses great challenges to human activity.Here,we reconstruct a 4000-year maternal genetic history of Tibetans using 128 ancient mitochondrial genome data from 37 sites in Tibet.The phylogeny of haplotypes M9a1a,M9a1b,D4g2,G2a’c,and D4i show that ancient Tibetans share the most recent common ancestor with ancient Middle and Upper Yellow River populations around the Early and Middle Holocene.In addition,the connections between Tibetans and Northeastern Asians vary over the past 4000 years,with a stronger matrilineal connection between the two during 4000 BPe3000 BP,and a weakened connection after 3000 BP,that are coincident with climate change,followed by a reinforced connection after the Tubo period(1400 BPe1100 BP).Besides,an over 4000-year matrilineal continuity is observed in some of the maternal lineages.We also find the maternal genetic structure of ancient Tibetans is correlated to the geography and interactions between ancient Tibetans and ancient Nepal and Pakistan populations.Overall,the maternal genetic history of Tibetans can be characterized as a long-term matrilineal continuity with frequent internal and external population interactions that are dynamically shaped by geography,climate changes,as well as historical events.
基金the Guangdong Basic and Applied Basic Research Foundation(grant No.2021B1515120028)National Natural Science Foundation of China(grant Nos.52130204,52174376,51822405,and 52202070)+5 种基金Science and Technology Innovation Team Plan of Shann Xi Province(grant No.2021TD-17)Youth Innovation Team of Shaanxi UniversitiesThousands Person Plan of Jiangxi Province(grant No.JXSQ2020102131)Xi’an Science and Technology Program(grant No.21ZCZZHXJS-QCY6-0005)Fundamental Research Funds for the Central Universities(grant Nos.D5000210902 and D5000220057)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(grant No.CX2022033).
文摘A novel AlCoCrFeNi2.1 eutectic high entropy alloy(EHEA)composite doped with SiC particles was designed and fabricated by laser powder bed fusion(LPBF).Its microstructure characteristic,tensile properties,and metallurgical defects,with an emphasis on cracking behavior,have been investigated.The results showed that the addition of SiC particles into the AlCoCrFeNi_(2.1)matrix enabled the development of a{100}texture and highly elongated columnar grains,which were the main contributors to mechanical behavior anisotropy.The ultimate tensile strength of 1466±26 MPa and elongation of 9%±3%achieved in the as-deposited EHEA composite surpassed those of advanced metal alloys subjected to additive manufacturing processes.Unfortunately,severe horizontal and longitudinal cracks,as well as a few micro-cracks were observed in the as-deposited bulk samples.Micro-cracks were verified to be associated with the aggregation of carbon and oxide particles.They formed in the final stage of solidification owing to insufficient liquid feeding ability and solidification contraction.The formation of macroscopic cracking was induced by the tensile stress accumulations at sample edges,and the stress concentration areas where microcracks and pores were located were the predominant propagation location.This work provides guidelines for defect control in SiC-reinforced EHEA,assisting in the high-performance design and integrated manufacturing of EHEA composite components.
基金supported by National Programs for Coordinated Promotion of Major Agricultural Technologies(Grant No.2021-ZYXT-02–1)Key Projects of Key research and Development Programs of Jiangsu Province(Grant No.BE2021323)+2 种基金the“333 Project”Scientific Research Project of Jiangsu Province(Grant No.70)Rural Revitalization Project of Huai’an(Grant No.HAN202312)Talent Introduction Research Project of Huaiyin Institute of Technology(Z301B22504).
文摘Melatonin and abscisic acid,as major plant hormones,play important roles in the physiological and biochemical activities of crops,but the interaction between the two under salt stress is not yet clear.This study investigated the endogenous levels of melatonin and abscisic acid in rice by using exogenous melatonin,abscisic acid,and their synthetic inhibitors,and examined their interactions under salt stress.The research results indicate that melatonin and abscisic acid can improve rice salt tolerance.Melatonin alleviated the salt sensitivity caused by abscisic acid deficiency,increased antioxidant enzyme activity and antioxidant content in rice treated with abscisic acid synth-esis inhibitors,and reduced total reactive oxygen species content and thiobarbituric acid reactive substance accu-mulation.Melatonin also increased the activity of key photosynthetic enzymes and the content of photosynthetic pigments,maintaining the parameters of photosynthetic gas exchange and chlorophyllfluorescence.In summary,melatonin alleviated the effects of abscisic acid deficiency on photosynthesis and antioxidant systems in rice and improved salt tolerance.This study is beneficial for expanding the understanding of melatonin regulation of crop salt tolerance.
基金supported by the Shanghai Science and Tech-nology Committee(No.22511102400)Prof.Zhang would like to appreciate the financial support from the Fundamental Research Funds for the Central Universities(No.2232020G-12)+1 种基金the Fund of National Engineering Research Center for Commercial Aircraft Manufacturing(No.COMAC-SFGS-2022-2376)the Textile Vi-sion Basic Research Program(No.J202105).
文摘In this study, two-dimensional MXene (Ti3 C2 Tx ) was employed to modify the interface of carbon fiber-reinforced polyetherketoneketone (CF/PEKK) composites, in order to simultaneously improve the electromagnetic interference (EMI) shielding performances and mechanical properties. The obtained CF/PEKK composites possessed outstanding EMI and mechanical performances, as anticipated. Specifically, the CF/PEKK composites modified with MXene at 1 mg mL–1 exhibited an excellent EMI shielding effectiveness of 65.2 dB in the X-band, a 103.1% enhancement compared with the unmodified CF/PEKK composites. The attractive EMI shielding performances of CF/PEKK composites originated from enhanced ohmic losses and multiple reflections of electromagnetic waves with the help of the MXene and CF layers. In addition, CF/PEKK composites achieved the best mechanical properties by optimizing the dispersion concentration of MXene to 0.1 mg mL–1 . The flexural strength, flexural modulus, and interlaminar shear strength of CF/PEKK composites reached 1127 MPa, 81 GPa, and 89 MPa, which were 28.5%, 9.5%, and 29.7% higher than that of the unmodified CF/PEKK composites, respectively. Such improvement in mechanical properties could be ascribed to the comprehensive effect of mechanical interlocking, hydrogen bonds, and Van der Waals forces between the introduced MXene and CF, PEKK, respectively.
基金supported by the National Natural Science Foundation of China(Grant Nos.12072299,11902276)the Natural Science Foundation of Sichuan Province(Grant No.2022NSFSC1802)+1 种基金the Basic Research Project of Southwest Jiaotong University(Grant No.2682023ZTPY009)the National Key Laboratory for Shock Wave and Detonation Physics of China(Grant No.JCKYS2019212007)。
文摘By combination of the transient Raman spectroscopic measurement and the density functional theoretical calculations,the structural evolution and stability of TATB under shock compression was investigated.Due to the improvement in synchronization control between two-stage light gas gun and the transient Raman spectra acquisition,as well as the sample preparation,the Raman peak of the N-O mode of TATB was firstly observed under shock pressure up to 13.6 GPa,noticeably higher than the upper limit of 8.5 GPa reported in available literatures.By taking into account of the continuous shift of the main peak and other observed Raman peaks,we did not distinguish any structural transition or any new species.Moreover,both the present Raman spectra and the time-resolved radiation of TATB during shock loading showed that TATB exhibits higher chemical stability than previous declaration.To reveal the detailed structural response and evolution of TATB under compression,the density functional theoretical calculations were conducted,and it was found that the pressure make N-O bond lengths shorter,nitro bond angles larger,and intermolecular and intra-molecular hydrogen bond interactions enhanced.The observed red shift of Raman peak was ascribed to the abnormal enhancement of H-bound effect on the scissor vibration mode of the nitro group.
