An overview of the recently renovated high-pressure X-ray diffraction(XRD)BL10XU beamline for the diamond anvil cell at SPring-8 is presented.The renovation includes the replacement of the X-ray source and monochromat...An overview of the recently renovated high-pressure X-ray diffraction(XRD)BL10XU beamline for the diamond anvil cell at SPring-8 is presented.The renovation includes the replacement of the X-ray source and monochromator,enhanced focusing systems for high-energy XRD,and recent progress in the sample environment control techniques that are available for high-pressure studies.Other simultaneous measurement techniques for combination with XRD,such as Raman scattering spectroscopy and Mossbauer spectroscopy,have been developed to obtain complementary information under extreme conditions.These advanced techniques are expected to make significant contributions to in-depth understanding of various and complicated high-pressure phenomena.The experience gained with the BL10XU beamline could help promote high-pressure research in future synchrotron radiation facilities.展开更多
Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet.Here we speculate the processes that led to the birth of early life on Earth and its aftermath, fi...Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet.Here we speculate the processes that led to the birth of early life on Earth and its aftermath, finally leading to the evolution of metazoans.We evaluate：（1） the source of nutrients,（2） the chemistry of primordial ocean,（3） the initial mass of ocean,and（4） the size of planet.Among the life-building nutrients,phosphorus and potassium play a key role.Only three types of rocks can serve as an adequate source of nutrients：（a） continent-forming TTG（granite）,enabling the evolution of primitive life to metazoans;（b） primordial continents carrying anorthosite with KREEP（Potassium,Rare Earth Elements, and Phosphorus） basalts,which is a key to bear life;（c） carbonatite magma,enriched in radiogenic elements such as U and Th,which can cause mutation to speed up evolution and promote the birth of new species in continental rift settings.The second important factor is ocean chemistry.The primordial ocean was extremely acidic（pH = 1-2） and enriched in halogens（CI,F and others）,S,N and metallic elements（Cd,Cu,Zn,and others）,inhibiting the birth of life.Plate tectonics cleaned up these elements which interfered with RNA.Blue ocean finally appeared in the Phanerozoic with pH = 7 through extensive interaction with surface continental crust by weathering,erosion and transportation into ocean.The initial ocean mass was also important.The birth of life and aftermath of evolution was possible in the habitable zone with 3-5 km deep ocean which was able to supply sufficient nutrients. Without a huge landmass,nutrients cannot be supplied into the ocean only by ridge-hydrothermal circulation in the Hadean.Finally,the size of the planet plays a crucial role.Cooling of massive planets is less efficient than smaller ones,so that return-flow of seawater into mantle does not occur until central stars finish their main sequence.Due to the suitable size of Earth,the dawn of Phanerozoic witnessed the initiation of return-flow of seawater into the mantle,leading to the emergence of huge landmass above sea-level,and the distribution of nutrients on a global scale.Oxygen pump also played a critical role to keep high-PO_2 in atmosphere since then,leading to the emergence of ozone layer and enabling animals and plants to invade the land. To satisfy the tight conditions to make the Earth habitable,the formation mechanism of primordial Earth is an important factor.At first,a ＇dry Earth＇ must be made through giant impact,followed by magma ocean to float nutrient-enriched primordial continents（anorthosite ＋ KREEP）.Late bombardment from asteroid belt supplied water to make 3-5 km thick ocean,and not from icy meteorites from Kuiper belt beyond cool Jupiter.It was essential to meet the above conditions that enabled the Earth as a habitable planet with evolved life forms.The tight constraints that we evaluate for birth and evolution of life on Earth would provide important guidelines for planetary scientists hunting for life in the exosolar planets.展开更多
^(95)Zr(n,γ)^(96)Zr是稳定燃烧的恒星中合成^(96)Zr的唯一途径,对研究恒星演化和重元素合成具有重要的意义。由于^(95)Zr半衰期为64 d,直接测量^(95)Zr(n,γ)^(96)Zr截面极为困难,因此,本工作采用替代比率法间接测量^(95)Zr(n,γ)^(96...^(95)Zr(n,γ)^(96)Zr是稳定燃烧的恒星中合成^(96)Zr的唯一途径,对研究恒星演化和重元素合成具有重要的意义。由于^(95)Zr半衰期为64 d,直接测量^(95)Zr(n,γ)^(96)Zr截面极为困难,因此,本工作采用替代比率法间接测量^(95)Zr(n,γ)^(96)Zr截面。本工作测量了^(94)Zr(^(18)O,^(16)Oγ)^(96)Zr和^(90)Zr(^(18)O,^(16)Oγ)^(92)Zr反应,得到了复合核^(96)Zr*和^(90)Zr*衰变到γ道的几率比,并利用截面已知的^(91)Zr(n,γ)^(92)Zr截面乘以实验所测比率,得到了En=0～8 Me V能区的^(95)Zr(n,γ)^(96)Zr中子俘获截面。展开更多
基金This work was partially supported by RIKEN,Japan,and MEXT/JSPS KAKENHI GrantsNos.JP24000005 and JP16H06285(to K.H.),JP26000006(to K.S.),and JP22000002 and JP15H05748(to E.O.).This work was performed under SPring-8 proposals.43 Comments from anonymous reviewers were helpful in improving the manuscript.
文摘An overview of the recently renovated high-pressure X-ray diffraction(XRD)BL10XU beamline for the diamond anvil cell at SPring-8 is presented.The renovation includes the replacement of the X-ray source and monochromator,enhanced focusing systems for high-energy XRD,and recent progress in the sample environment control techniques that are available for high-pressure studies.Other simultaneous measurement techniques for combination with XRD,such as Raman scattering spectroscopy and Mossbauer spectroscopy,have been developed to obtain complementary information under extreme conditions.These advanced techniques are expected to make significant contributions to in-depth understanding of various and complicated high-pressure phenomena.The experience gained with the BL10XU beamline could help promote high-pressure research in future synchrotron radiation facilities.
文摘Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet.Here we speculate the processes that led to the birth of early life on Earth and its aftermath, finally leading to the evolution of metazoans.We evaluate：（1） the source of nutrients,（2） the chemistry of primordial ocean,（3） the initial mass of ocean,and（4） the size of planet.Among the life-building nutrients,phosphorus and potassium play a key role.Only three types of rocks can serve as an adequate source of nutrients：（a） continent-forming TTG（granite）,enabling the evolution of primitive life to metazoans;（b） primordial continents carrying anorthosite with KREEP（Potassium,Rare Earth Elements, and Phosphorus） basalts,which is a key to bear life;（c） carbonatite magma,enriched in radiogenic elements such as U and Th,which can cause mutation to speed up evolution and promote the birth of new species in continental rift settings.The second important factor is ocean chemistry.The primordial ocean was extremely acidic（pH = 1-2） and enriched in halogens（CI,F and others）,S,N and metallic elements（Cd,Cu,Zn,and others）,inhibiting the birth of life.Plate tectonics cleaned up these elements which interfered with RNA.Blue ocean finally appeared in the Phanerozoic with pH = 7 through extensive interaction with surface continental crust by weathering,erosion and transportation into ocean.The initial ocean mass was also important.The birth of life and aftermath of evolution was possible in the habitable zone with 3-5 km deep ocean which was able to supply sufficient nutrients. Without a huge landmass,nutrients cannot be supplied into the ocean only by ridge-hydrothermal circulation in the Hadean.Finally,the size of the planet plays a crucial role.Cooling of massive planets is less efficient than smaller ones,so that return-flow of seawater into mantle does not occur until central stars finish their main sequence.Due to the suitable size of Earth,the dawn of Phanerozoic witnessed the initiation of return-flow of seawater into the mantle,leading to the emergence of huge landmass above sea-level,and the distribution of nutrients on a global scale.Oxygen pump also played a critical role to keep high-PO_2 in atmosphere since then,leading to the emergence of ozone layer and enabling animals and plants to invade the land. To satisfy the tight conditions to make the Earth habitable,the formation mechanism of primordial Earth is an important factor.At first,a ＇dry Earth＇ must be made through giant impact,followed by magma ocean to float nutrient-enriched primordial continents（anorthosite ＋ KREEP）.Late bombardment from asteroid belt supplied water to make 3-5 km thick ocean,and not from icy meteorites from Kuiper belt beyond cool Jupiter.It was essential to meet the above conditions that enabled the Earth as a habitable planet with evolved life forms.The tight constraints that we evaluate for birth and evolution of life on Earth would provide important guidelines for planetary scientists hunting for life in the exosolar planets.
文摘^(95)Zr(n,γ)^(96)Zr是稳定燃烧的恒星中合成^(96)Zr的唯一途径,对研究恒星演化和重元素合成具有重要的意义。由于^(95)Zr半衰期为64 d,直接测量^(95)Zr(n,γ)^(96)Zr截面极为困难,因此,本工作采用替代比率法间接测量^(95)Zr(n,γ)^(96)Zr截面。本工作测量了^(94)Zr(^(18)O,^(16)Oγ)^(96)Zr和^(90)Zr(^(18)O,^(16)Oγ)^(92)Zr反应,得到了复合核^(96)Zr*和^(90)Zr*衰变到γ道的几率比,并利用截面已知的^(91)Zr(n,γ)^(92)Zr截面乘以实验所测比率,得到了En=0～8 Me V能区的^(95)Zr(n,γ)^(96)Zr中子俘获截面。
