The China Spallation Neutron Source (CSNS) is an accelerator-based facility. The accelerator of CSNS consists of a low energy linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. The overall physics ...The China Spallation Neutron Source (CSNS) is an accelerator-based facility. The accelerator of CSNS consists of a low energy linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. The overall physics design of CSNS accelerator is described, including the design principle, the choice of the main parameters and design of each part of accelerators. The key problems of the physics design, such as beam loss and control, are also discussed. The interface between the different parts of accelerator, as well as between accelerator and target, are introduced.展开更多
In this review, acritical look at the research progress ofexperimentalsolid mechanics in China for the past years is presented. Issues are discussed of the discovery and development of new fundamental methods and tech...In this review, acritical look at the research progress ofexperimentalsolid mechanics in China for the past years is presented. Issues are discussed of the discovery and development of new fundamental methods and techniques versus performance benchmarking for many of their applications. Included herein are photoelasticity and various forms of modern photomechanics, acoustical techniques, image processing and videometrics, radial and spectrum techniques, and experimental mechanics on micro/nano scale. It is also noticed that both the ever developed instrumentation and specialized synthetical techniques have played important roles in advancing experimental mechanics in scientific researches and industrial applications. Finally, an attempt is made to look into the future of experimental solid mechanics with personal opinions offered on what the future trends will be for the researches in the field.展开更多
The protein complex crystallographic beamline BL19U1 at the Shanghai Synchrotron Radiation Facility is one of the five beamlines dedicated to protein sciences operated by National Facility for Protein Science(Shanghai...The protein complex crystallographic beamline BL19U1 at the Shanghai Synchrotron Radiation Facility is one of the five beamlines dedicated to protein sciences operated by National Facility for Protein Science(Shanghai,China).The beamline,which features a small-gap invacuum undulator,has been officially open to users since March 2015.This beamline delivers X-ray in the energy range 7–15 keV.With its high flux,low divergence beam and a large active area detector,BL19U1 is designed for proteins with large molecular weight and large crystallographic unit cell dimensions.Good performance and stable operation of the beamline have allowed the number of Protein Data Bank(PDB)depositions and the number of articles published based on data collected at this beamline to increase steadily.To date,over 300 research groups have collected data at the beamline.More than 600 PDB entries have been deposited at the PDB(www.pdb.org).More than 300 papers have been published that include data collected at the beamline,including 21 research articles published in the top-level journals Cell,Nature,and Science.展开更多
The China Spallation Neutron Source (CSNS) is the first accelerator-based pulsed neutron source in China. Its accelerators are made up of an 80 MeV H- linac, a Rapid Cycling Synchrotron (RCS) and two beam transport li...The China Spallation Neutron Source (CSNS) is the first accelerator-based pulsed neutron source in China. Its accelerators are made up of an 80 MeV H- linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. RCS accumulates and accelerates protons to the design energy of 1.6 GeV, and extracts high energy beam to strike the target. The overview of RCS is presented, and the key problems of the physics design are discussed. The two beam transport lines, from linac to RCS and from RCS to the target, are also introduced.展开更多
From a safety point of view, it is important to study the damages and reliability of molten salt reactor structural alloy materials, which are subjected to extreme environments due to neutron irradiation, molten salt ...From a safety point of view, it is important to study the damages and reliability of molten salt reactor structural alloy materials, which are subjected to extreme environments due to neutron irradiation, molten salt corrosion, fission product attacks, thermal stress, and even combinations of these. In the past few years, synchrotron radiation-based materials characterization techniques have proven to be effective in revealing the microstructural evolution and failure mechanisms of the alloys under surrogating operation conditions. Here, we review the recent progress in the investigations of molten salt corrosion,tellurium(Te) corrosion, and alloy design. The valence states and distribution of chromium(Cr) atoms, and the diffusion and local atomic structure of Te atoms near the surface of corroded alloys have been investigated using synchrotron radiation techniques, which considerably deepen the understandings on the molten salt and Te corrosion behaviors. Furthermore, the structure and size distribution of the second phases in the alloys have been obtained, which are helpful for the future development of new alloy materials.展开更多
Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorp...Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorption near edge structure spectroscopy was established to analyze the sulfur concentration and speciation in mature camphor tree leaves （CTLs）,which were sampled from 5 local fields in Shanghai,China.Annual SO2 concentration,SO42-concentration in atmospheric particulate,SO42-and sulfur concentration in soil were also analyzed to explore the relationship between ambient sulfur sources and the sulfur nutrient cycling in CTLs.Total sulfur concentration in mature camphor tree leaves was 766-1704 mg/kg.The mainly detected sulfur states and their corresponding compounds were ＋6 （sulfate,include inorganic sulfate and organic sulfate）,＋5.2 （sulfonate）,＋2.2 （suloxides）,＋0.6 （thiols and thiothers）,＋0.2 （organic sulfides）.Total sulfur concentration was strongly correlated with sulfate proportion with a linear correlation coefficient up to 0.977,which suggested that sulfur accumulated in CTLs as sulfate form.Reduced sulfur compounds （organic sulfides,thiols,thioethers,sulfoxide and sulfonate） assimilation was sufficed to meet the nutrient requirement for growth at a balanced level around 526 mg/kg.The sulfate accumulation mainly caused by atmospheric sulfur pollution such as SO2 and airborne sulfate particulate instead of soil contamination.From urban to suburb place,sulfate in mature CTLs decreased as the atmospheric sulfur pollution reduced,but a dramatic increase presented near the seashore,where the marine sulfate emission and maritime activity pollution were significant.The sulfur concentration and speciation in mature CTLs effectively represented the long-term biological accumulation of atmospheric sulfur pollution in local environment.展开更多
The effect of cooling rate on the transition of dendrite morphology of a Mg-6Gd （wt%） alloy was semiquantitatively analyzed under a constant temperature gradient by using synchrotron X-ray radiographic technique. Re...The effect of cooling rate on the transition of dendrite morphology of a Mg-6Gd （wt%） alloy was semiquantitatively analyzed under a constant temperature gradient by using synchrotron X-ray radiographic technique. Results show that equiaxed dendrites, including exotic ＇butterfly-shaped＇ dendrite morphology, dominate at high cooling rate （〉1 K/s）. When the cooling rate decreases in the range of 0.5-1 K/s, the equiaxed-to-columnar transition takes place, and solute segregates at the center of two long dendrite arms （LDA） of the ＇butterfly-shaped＇ dendrite. When the cooling rate is lower than 0.3 K/s, directional solidification occurs and the columnar dendritic growth direction gradually rotates from the crystalline axis to the thermal gradient direction with an increase in cooling rate. Meanwhile, interface moves faster but the dendrite arm spacing decreases. Floating, collision and rotation of dendrites under convection were also studied in this work.2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.展开更多
Beamline BL17 U1 at Shanghai Synchrotron Radiation Facility is an energy-tunable macromolecular crystallography beamline that has been in user operation since 2009. Growing demand from the user community for a small b...Beamline BL17 U1 at Shanghai Synchrotron Radiation Facility is an energy-tunable macromolecular crystallography beamline that has been in user operation since 2009. Growing demand from the user community for a small beam and related experimental methods have motivated upgrades of the devices in the endstation.Minibeam modes have already been developed for operation. A self-integrated diffractometer reduces the sphere of confusion of the rotatory axis to 1μm. The new diffractometer is equipped with an upgraded on-axis viewing system that can improve the resolving power. Additionally,the area detector was also upgraded to the newest generation of detectors, the EIGER X 16 M, which can collect data at 133 Hz. After these upgrades, the endstation became virtually new. This paper covers the upgrade of the endstation devices and gives the first data collection results.展开更多
Recently we are witnessing the boom of high-pressure science and technology from a small niche field to becoming a major dimension in physical sciences.One of the most important technological advances is the integrati...Recently we are witnessing the boom of high-pressure science and technology from a small niche field to becoming a major dimension in physical sciences.One of the most important technological advances is the integration of synchrotron nanotechnology with the minute samples at ultrahigh pressures.Applications of high pressure have greatly enhanced our understanding of the electronic,phonon,and doping effects on the newly emerged graphene and related 2D layered materials.High pressure has created exotic stoichiometry even in common Group 17,15,and 14 compounds and drastically altered the basic σ and π bonding of organic compounds.Differential pressure measurements enable us to study the rheology and flow of mantle minerals in solid state,thus quantitatively constraining the geodynamics.They also introduce a new approach to understand defect and plastic deformations of nano particles.These examples open new frontiers of high-pressure research.展开更多
The concentration ranges of As and Sb in six Late Permian high-arsenic coals collected from Xingren and Xingyi, Guizhou Province are 94.1 μg·g -1-3 2 and 8 1 μg·g -1-120 μg·g -1, respectively. Based ...The concentration ranges of As and Sb in six Late Permian high-arsenic coals collected from Xingren and Xingyi, Guizhou Province are 94.1 μg·g -1-3 2 and 8 1 μg·g -1-120 μg·g -1, respectively. Based on the mineralogical analysis, no arsenic and arsenic-bearing minerals are detected in these samples and arsenic occurs in coal macerals. By extended X-ray absorption fine structure(EXAFS) spectroscopy, we have found that arsenic in these high-arsenic coal samples coordinates with oxygen; the coordination number of As with oxygen for these samples is 4 except one sample(H-9) for which the coordination number of As is 3. Therefore, arsenic in these high-arsenic coals does not occur in sulfide minerals, but occurs in arsenate or arsenite phase, and the preponderance of As is in arsenate of As 5+.展开更多
This study was trying to observe the real-time dendrite growth of Sn-Bi and Sn-Pb binary alloys by a synchrotron radiation imaging technology.The imaging system includes an intense and high brightness synchrotron radi...This study was trying to observe the real-time dendrite growth of Sn-Bi and Sn-Pb binary alloys by a synchrotron radiation imaging technology.The imaging system includes an intense and high brightness synchrotron radiation source,a high-resolution and fast-readout charge coupled device camera,an alloy sample and a Bridgman solidification system.The imaging experiments were done at Beijing Synchrotron Radiation Facility with an updated synchrotron radiation imaging technique,diffraction-enhanced imaging,which was firstly used to study the dendrite growth of metallic alloy.A series of growth behavior and morphology evolution of dendrite have been in situ observed,such as columnar-to-equiaxed transition,dendrite competition,dendrite fragmentation and floating,etc.,which can offer the direct proofs to verify or improve the solidification theories of metallic alloy.This research opens a novel window for the study of alloy solidification and enables the unambiguous understanding of solidification processes in optically opaque,metallic alloys.展开更多
In situ synchrotron X-ray radiography was used to study the effect of direct current（DC） on the grain nucleation and growth of Sn-50 wt.%Pb alloy. The results showed that applying DC adequately during solidification...In situ synchrotron X-ray radiography was used to study the effect of direct current（DC） on the grain nucleation and growth of Sn-50 wt.%Pb alloy. The results showed that applying DC adequately during solidification could effectively enhance the grain nucleation and inhibit its growth. Imaging of comparative experiments with varying DC intensity indicated that the final grain size, determined by the competition between grain nucleation and growth, was sensitively dependent on the DC intensity. It was found that the average grain size was decreased from 1632 to 567 μm with DC density of 1.5 A/mm^2 compared to the case without DC. Beyond this value, raising the current density may cause a significant decrease in the nucleation rate, and thus lead to a coarsening of the grain structure.展开更多
X-ray fluorescence CT is a non-destructive technique for detecting elemental composition and distribution inside a specimen. In this paper, the first experimental results of X-ray fluorescence CT obtained at the SSRF ...X-ray fluorescence CT is a non-destructive technique for detecting elemental composition and distribution inside a specimen. In this paper, the first experimental results of X-ray fluorescence CT obtained at the SSRF X-ray imaging beamline （BL13W1） are described. The test samples were investigated and the 2D elemental image was reconstructed using a filtered back-projection algorithm. In the sample the element Cd was observed. Up to now, the X-ray fluorescence CT could be carried out at the SSRF X-ray imaging beamline.展开更多
文摘The China Spallation Neutron Source (CSNS) is an accelerator-based facility. The accelerator of CSNS consists of a low energy linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. The overall physics design of CSNS accelerator is described, including the design principle, the choice of the main parameters and design of each part of accelerators. The key problems of the physics design, such as beam loss and control, are also discussed. The interface between the different parts of accelerator, as well as between accelerator and target, are introduced.
基金Project supported by the NSFC (Nos.10472112,19232020,10627201,10972113, 90916010 and 10732080)the National Basic Research Program of China (Nos.2007CB936803 and 2010CB631005)SRFDP (Nos.20070003053 and 20090002110048)
文摘In this review, acritical look at the research progress ofexperimentalsolid mechanics in China for the past years is presented. Issues are discussed of the discovery and development of new fundamental methods and techniques versus performance benchmarking for many of their applications. Included herein are photoelasticity and various forms of modern photomechanics, acoustical techniques, image processing and videometrics, radial and spectrum techniques, and experimental mechanics on micro/nano scale. It is also noticed that both the ever developed instrumentation and specialized synthetical techniques have played important roles in advancing experimental mechanics in scientific researches and industrial applications. Finally, an attempt is made to look into the future of experimental solid mechanics with personal opinions offered on what the future trends will be for the researches in the field.
文摘The protein complex crystallographic beamline BL19U1 at the Shanghai Synchrotron Radiation Facility is one of the five beamlines dedicated to protein sciences operated by National Facility for Protein Science(Shanghai,China).The beamline,which features a small-gap invacuum undulator,has been officially open to users since March 2015.This beamline delivers X-ray in the energy range 7–15 keV.With its high flux,low divergence beam and a large active area detector,BL19U1 is designed for proteins with large molecular weight and large crystallographic unit cell dimensions.Good performance and stable operation of the beamline have allowed the number of Protein Data Bank(PDB)depositions and the number of articles published based on data collected at this beamline to increase steadily.To date,over 300 research groups have collected data at the beamline.More than 600 PDB entries have been deposited at the PDB(www.pdb.org).More than 300 papers have been published that include data collected at the beamline,including 21 research articles published in the top-level journals Cell,Nature,and Science.
文摘The China Spallation Neutron Source (CSNS) is the first accelerator-based pulsed neutron source in China. Its accelerators are made up of an 80 MeV H- linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. RCS accumulates and accelerates protons to the design energy of 1.6 GeV, and extracts high energy beam to strike the target. The overview of RCS is presented, and the key problems of the physics design are discussed. The two beam transport lines, from linac to RCS and from RCS to the target, are also introduced.
基金supported by the National key research and development program of China(Nos.2016YFB0700401 and 2016YFB0700404)Natural Science Foundation of Shanghai(Nos.19ZR1468200 and 18ZR1448000)+2 种基金National Natural Science Foundation of China(Nos.51671154,51601213 and 51671122)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA02004210)Youth Innovation Promotion Association,Chinese Academy of Science(No.2019264)
文摘From a safety point of view, it is important to study the damages and reliability of molten salt reactor structural alloy materials, which are subjected to extreme environments due to neutron irradiation, molten salt corrosion, fission product attacks, thermal stress, and even combinations of these. In the past few years, synchrotron radiation-based materials characterization techniques have proven to be effective in revealing the microstructural evolution and failure mechanisms of the alloys under surrogating operation conditions. Here, we review the recent progress in the investigations of molten salt corrosion,tellurium(Te) corrosion, and alloy design. The valence states and distribution of chromium(Cr) atoms, and the diffusion and local atomic structure of Te atoms near the surface of corroded alloys have been investigated using synchrotron radiation techniques, which considerably deepen the understandings on the molten salt and Te corrosion behaviors. Furthermore, the structure and size distribution of the second phases in the alloys have been obtained, which are helpful for the future development of new alloy materials.
基金supported by the National Natural Science Foundation of China(No.11079049,11005141,10775150)the Major Project of Knowledge Innovation Program of Chinese Academy of Sciences(No.KJCX3.SYW.N3)
文摘Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorption near edge structure spectroscopy was established to analyze the sulfur concentration and speciation in mature camphor tree leaves （CTLs）,which were sampled from 5 local fields in Shanghai,China.Annual SO2 concentration,SO42-concentration in atmospheric particulate,SO42-and sulfur concentration in soil were also analyzed to explore the relationship between ambient sulfur sources and the sulfur nutrient cycling in CTLs.Total sulfur concentration in mature camphor tree leaves was 766-1704 mg/kg.The mainly detected sulfur states and their corresponding compounds were ＋6 （sulfate,include inorganic sulfate and organic sulfate）,＋5.2 （sulfonate）,＋2.2 （suloxides）,＋0.6 （thiols and thiothers）,＋0.2 （organic sulfides）.Total sulfur concentration was strongly correlated with sulfate proportion with a linear correlation coefficient up to 0.977,which suggested that sulfur accumulated in CTLs as sulfate form.Reduced sulfur compounds （organic sulfides,thiols,thioethers,sulfoxide and sulfonate） assimilation was sufficed to meet the nutrient requirement for growth at a balanced level around 526 mg/kg.The sulfate accumulation mainly caused by atmospheric sulfur pollution such as SO2 and airborne sulfate particulate instead of soil contamination.From urban to suburb place,sulfate in mature CTLs decreased as the atmospheric sulfur pollution reduced,but a dramatic increase presented near the seashore,where the marine sulfate emission and maritime activity pollution were significant.The sulfur concentration and speciation in mature CTLs effectively represented the long-term biological accumulation of atmospheric sulfur pollution in local environment.
基金financially supported by the Program of Shanghai Subject Chief Engineering (No. 14XD1425000)the National Natural Science Foundation of China (No. 51304135)the Chinese Scholarship Council and DOE (No. DE-FG02-07ER46417)
文摘The effect of cooling rate on the transition of dendrite morphology of a Mg-6Gd （wt%） alloy was semiquantitatively analyzed under a constant temperature gradient by using synchrotron X-ray radiographic technique. Results show that equiaxed dendrites, including exotic ＇butterfly-shaped＇ dendrite morphology, dominate at high cooling rate （〉1 K/s）. When the cooling rate decreases in the range of 0.5-1 K/s, the equiaxed-to-columnar transition takes place, and solute segregates at the center of two long dendrite arms （LDA） of the ＇butterfly-shaped＇ dendrite. When the cooling rate is lower than 0.3 K/s, directional solidification occurs and the columnar dendritic growth direction gradually rotates from the crystalline axis to the thermal gradient direction with an increase in cooling rate. Meanwhile, interface moves faster but the dendrite arm spacing decreases. Floating, collision and rotation of dendrites under convection were also studied in this work.2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.
基金supported by the Maintenance and Renovation Project for the major infrastructure of the Chinese Academy of Sciencesthe Operation Project of SSRF
文摘Beamline BL17 U1 at Shanghai Synchrotron Radiation Facility is an energy-tunable macromolecular crystallography beamline that has been in user operation since 2009. Growing demand from the user community for a small beam and related experimental methods have motivated upgrades of the devices in the endstation.Minibeam modes have already been developed for operation. A self-integrated diffractometer reduces the sphere of confusion of the rotatory axis to 1μm. The new diffractometer is equipped with an upgraded on-axis viewing system that can improve the resolving power. Additionally,the area detector was also upgraded to the newest generation of detectors, the EIGER X 16 M, which can collect data at 133 Hz. After these upgrades, the endstation became virtually new. This paper covers the upgrade of the endstation devices and gives the first data collection results.
文摘Recently we are witnessing the boom of high-pressure science and technology from a small niche field to becoming a major dimension in physical sciences.One of the most important technological advances is the integration of synchrotron nanotechnology with the minute samples at ultrahigh pressures.Applications of high pressure have greatly enhanced our understanding of the electronic,phonon,and doping effects on the newly emerged graphene and related 2D layered materials.High pressure has created exotic stoichiometry even in common Group 17,15,and 14 compounds and drastically altered the basic σ and π bonding of organic compounds.Differential pressure measurements enable us to study the rheology and flow of mantle minerals in solid state,thus quantitatively constraining the geodynamics.They also introduce a new approach to understand defect and plastic deformations of nano particles.These examples open new frontiers of high-pressure research.
文摘The concentration ranges of As and Sb in six Late Permian high-arsenic coals collected from Xingren and Xingyi, Guizhou Province are 94.1 μg·g -1-3 2 and 8 1 μg·g -1-120 μg·g -1, respectively. Based on the mineralogical analysis, no arsenic and arsenic-bearing minerals are detected in these samples and arsenic occurs in coal macerals. By extended X-ray absorption fine structure(EXAFS) spectroscopy, we have found that arsenic in these high-arsenic coal samples coordinates with oxygen; the coordination number of As with oxygen for these samples is 4 except one sample(H-9) for which the coordination number of As is 3. Therefore, arsenic in these high-arsenic coals does not occur in sulfide minerals, but occurs in arsenate or arsenite phase, and the preponderance of As is in arsenate of As 5+.
基金supported by the National Natural Science Foundation of China (Grant Nos.50601003,50971032)the Program for New Century Excellent Talents in University (Grant No.NCET-07-0137)
文摘This study was trying to observe the real-time dendrite growth of Sn-Bi and Sn-Pb binary alloys by a synchrotron radiation imaging technology.The imaging system includes an intense and high brightness synchrotron radiation source,a high-resolution and fast-readout charge coupled device camera,an alloy sample and a Bridgman solidification system.The imaging experiments were done at Beijing Synchrotron Radiation Facility with an updated synchrotron radiation imaging technique,diffraction-enhanced imaging,which was firstly used to study the dendrite growth of metallic alloy.A series of growth behavior and morphology evolution of dendrite have been in situ observed,such as columnar-to-equiaxed transition,dendrite competition,dendrite fragmentation and floating,etc.,which can offer the direct proofs to verify or improve the solidification theories of metallic alloy.This research opens a novel window for the study of alloy solidification and enables the unambiguous understanding of solidification processes in optically opaque,metallic alloys.
基金supported by the National Key Research and Development Program of China (No. 2016YFB0701203)the National Natural Science Foundation of China (Nos. 51525401, 51690163, 51601028, 51401044)Dalian Support Plan for Innovation of High-level Talents (Top and Leading Talents, 2015R013)
文摘In situ synchrotron X-ray radiography was used to study the effect of direct current（DC） on the grain nucleation and growth of Sn-50 wt.%Pb alloy. The results showed that applying DC adequately during solidification could effectively enhance the grain nucleation and inhibit its growth. Imaging of comparative experiments with varying DC intensity indicated that the final grain size, determined by the competition between grain nucleation and growth, was sensitively dependent on the DC intensity. It was found that the average grain size was decreased from 1632 to 567 μm with DC density of 1.5 A/mm^2 compared to the case without DC. Beyond this value, raising the current density may cause a significant decrease in the nucleation rate, and thus lead to a coarsening of the grain structure.
基金Supported by National Natural Science Foundation of China (10805071, 10705020)Major Research Plan of National Natural Science Foundation of China (2010CB834301)Chinese Academy of Sciences Key Project of International Co-operation(GJHZ09058)
文摘X-ray fluorescence CT is a non-destructive technique for detecting elemental composition and distribution inside a specimen. In this paper, the first experimental results of X-ray fluorescence CT obtained at the SSRF X-ray imaging beamline （BL13W1） are described. The test samples were investigated and the 2D elemental image was reconstructed using a filtered back-projection algorithm. In the sample the element Cd was observed. Up to now, the X-ray fluorescence CT could be carried out at the SSRF X-ray imaging beamline.
