Heavy ions such as 56Fe,which are main radiation sources in deep space,could have a high potential impact on health during space exploration.The effects of iron ion irradiation on the induction of developmental toxici...Heavy ions such as 56Fe,which are main radiation sources in deep space,could have a high potential impact on health during space exploration.The effects of iron ion irradiation on the induction of developmental toxicity and radiation-induced apoptosis and its potential mechanisms were studied in zebrafish(Danio rerio)embryos.展开更多
With deep-space exploration missions being extended,the impact of the space environment on the health of astronauts is attracting more and more concern.During space flight,exposure to relatively high doses and various...With deep-space exploration missions being extended,the impact of the space environment on the health of astronauts is attracting more and more concern.During space flight,exposure to relatively high doses and various forms of radiation.Iron ion(56Fe)is main radiation sources in deep space and has received much attention[1].Exposure to 56Fe radiation during space missions poses a significant risk to the central nervous system and radiation exposure significantly affects the hippocampus.Radiation exposure is intimately linked to the production of reactive oxygen species(ROS)and due to its high oxygen consumption and metabolic rate,the brain is more susceptible to ROS and oxidative stress than other organs.展开更多
^(56)Fe是反应堆屏蔽设计中的重要核素之一,量化^(56)Fe对屏蔽计算造成的不确定度,对确定反应堆屏蔽设计不确定度来源具有重要意义。本文首先利用评价核数据库抽样程序NECP-SOUL,基于JEFF-3.3、ENDF/B-Ⅷ.0进行抽样,然后对每个样本利用...^(56)Fe是反应堆屏蔽设计中的重要核素之一,量化^(56)Fe对屏蔽计算造成的不确定度,对确定反应堆屏蔽设计不确定度来源具有重要意义。本文首先利用评价核数据库抽样程序NECP-SOUL,基于JEFF-3.3、ENDF/B-Ⅷ.0进行抽样,然后对每个样本利用核数据处理程序NECP-Atlas制作适用于屏蔽计算的多群数据库,利用离散纵标输运程序NECP-hydra计算ASPIS-Fe与ALARM-CF-FE-SHIELD-001基准题,量化探测器反应率计算结果的不确定度。结果表明,随屏蔽材料厚度的增加,不确定度逐渐增大;仅对截面协方差进行抽样时,弹性散射与非弹性散射截面协方差对快中子探测器反应率不确定度有较大影响,对1 Me V以上中子敏感的^(32)S(n,p)^(32)P探测器造成的不确定度最大达20%以上;此外,在同时考虑截面协方差与次级粒子角分布协方差后,不确定度量化结果会比仅考虑截面协方差时增加约2%。展开更多
The K-shell ionization probability Pk was measured as a function of Ep across the strong resonance 56Fe(p,p)56Fe at 2.522 MeV and about 50 % variation was observed. For a large ratio of the K-shell binding energy to t...The K-shell ionization probability Pk was measured as a function of Ep across the strong resonance 56Fe(p,p)56Fe at 2.522 MeV and about 50 % variation was observed. For a large ratio of the K-shell binding energy to the total width of the nuclear resonance, Uk/Г≥5, the present experimental result is still in good agreement with theoretical calculation based on Blair and Anholt’s formula.展开更多
Using the shell-model Monte Carlo method and random phase approximation theory,we carry out an estimation on neutrino energy loss(NEL)of ^(52,53,54,55,56)Fe.We find the NEL rates increase greatly at some typical stell...Using the shell-model Monte Carlo method and random phase approximation theory,we carry out an estimation on neutrino energy loss(NEL)of ^(52,53,54,55,56)Fe.We find the NEL rates increase greatly at some typical stellar conditions,and even exceed eight orders of magnitude.On the other hand,in order to compare our results ofλ_(SMMC)^(LJ)(which are calculated by using the SMMC method)with those ofλ_(FFN)^(LJ)(which are calculated by using the Fuller-Fowler-Newman(FFN)method),the error factor C,betweenλ_(SMMC)^(LJ) andλ_(FFN)^(LJ),is discussed and shows that at higher density and temperature,the fit is fairly good for the two results(λ_(SMMC)^(LJ) andλ_(FFN)^(LJ)),and the maximum error is~6.20%.However,the maximum error is~95.50%(e.g.53Fe)at lower density and temperature.展开更多
Ericson formula represents the first formula, which was suggested to describe the partial level density (PLD) formula in pre-equilibrium region of the nuclear reactions. Then a number of corrections were added to this...Ericson formula represents the first formula, which was suggested to describe the partial level density (PLD) formula in pre-equilibrium region of the nuclear reactions. Then a number of corrections were added to this formula in order to make it more suitable to physical meaning. In this paper, there are two aims to be done: the first aim is to study the correspondence between one and two-components formulae in Ericson, Pauli, and pairing corrections;the second aim is to compare and study the results of Comprehensive formula, which contents with all corrections, with Ericson, Pauli, and pairing formulae. The Comprehensive formula was suggested to simulate the reality. To achieve these aims the 56Fe and 90Zr nuclei were chosen and the results showed that the difference between one and two-components formulae was too small which can be neglected. Furthermore, the results strongly recommended that for cross section calculations of the nuclear reaction, one must use Comprehensive formula rather than Pauli formula.展开更多
The Ediacaran-Cambrian transition is characterized by numerous events such as the emergence of large multi-cellular metazoans and surface environmental disturbances.Based on geological evidence,it has been proposed th...The Ediacaran-Cambrian transition is characterized by numerous events such as the emergence of large multi-cellular metazoans and surface environmental disturbances.Based on geological evidence,it has been proposed that this transition coincided with the increase in the atmospheric oxygen level that was key to the evolution of life.Even though ancient redox conditions can be inferred from the composition of sedimentary iron mineral species,this method is not necessarily applicable to all rocks.In the Earth system,the cycling of iron is of considerable interest owing to its sensitivity to redox conditions.Information regarding the paleo-oceanic iron cycle is revealed in the iron isotopic composition of ironbearing minerals.Unfortunately,only limited iron isotopic data exists for Ediacaran-to Cambrianperiod oceans.To circumvent this deficiency,we drilled a fossiliferous Ediacaran to Early Cambrian sedimentary succession in the Three Gorges region,South China.We analyzed the iron isotope ratios(δ^(56/54)Fe)of pyrite grains in the drill cores using laser ablation multi collector inductively coupled plasma mass spectrometry.The results demonstrate large variations inδ^(56/54)Fe,from-1.6 to 1.6‰,and positive iron isotope ratios are observed in many successions.The presence of positiveδ^(56/54)Fe in pyrite indicates that the ferrous iron in the seawater was partially oxidized,suggesting that seawater at Three Gorges was ferruginous during the Ediacaran and Early Cambrian periods.However,aggregated pyrite grains in organic carbon-rich black shales at Member 4 of the Doushantuo Formation and the base of the Shuijingtuo Formation yield near-zeroδ^(56/54)Fe values;this suggests that the ocean was transiently dominated by sulfidic conditions during these periods.Notably negativeδ^(56/54)Fe values,lower than-1‰,can be interpreted as a signature of DIR.The DIR also might contribute in part to the re-mineralization of organic matter during the largest negative carbon isotope anomaly in the Ediacaran.展开更多
The Fe48Cr15Mo14Er2C15B6amorphous steel can hardly be used as an engineering material because of its ex- treme brittleness and very low iron content. By changing the composition of the nonmagnetic amorphous steel, and...The Fe48Cr15Mo14Er2C15B6amorphous steel can hardly be used as an engineering material because of its ex- treme brittleness and very low iron content. By changing the composition of the nonmagnetic amorphous steel, and using the relation between the reduced glass transition tempera- ture Trg and the glass forming ability, a new amorphous Fe56Mn5Cr7Mo12Er2C12B6 alloy with good glass forming abil- ity and high iron content was obtained. The diameter of the as-cast sample rod reached 8 mm. This new amorphous steel has lower manufacturing cost due to its high iron content, and thus it can have wider applications.展开更多
基金Key Program of National Natural Science Foundation of China(U1432248)National Natural Science Foundation of China(11305226)。
文摘Heavy ions such as 56Fe,which are main radiation sources in deep space,could have a high potential impact on health during space exploration.The effects of iron ion irradiation on the induction of developmental toxicity and radiation-induced apoptosis and its potential mechanisms were studied in zebrafish(Danio rerio)embryos.
基金National Key Projects of Research and Development(2016YFC0904600)Key Program of National Natural Science Foundation of China(U1432248)。
文摘With deep-space exploration missions being extended,the impact of the space environment on the health of astronauts is attracting more and more concern.During space flight,exposure to relatively high doses and various forms of radiation.Iron ion(56Fe)is main radiation sources in deep space and has received much attention[1].Exposure to 56Fe radiation during space missions poses a significant risk to the central nervous system and radiation exposure significantly affects the hippocampus.Radiation exposure is intimately linked to the production of reactive oxygen species(ROS)and due to its high oxygen consumption and metabolic rate,the brain is more susceptible to ROS and oxidative stress than other organs.
文摘^(56)Fe是反应堆屏蔽设计中的重要核素之一,量化^(56)Fe对屏蔽计算造成的不确定度,对确定反应堆屏蔽设计不确定度来源具有重要意义。本文首先利用评价核数据库抽样程序NECP-SOUL,基于JEFF-3.3、ENDF/B-Ⅷ.0进行抽样,然后对每个样本利用核数据处理程序NECP-Atlas制作适用于屏蔽计算的多群数据库,利用离散纵标输运程序NECP-hydra计算ASPIS-Fe与ALARM-CF-FE-SHIELD-001基准题,量化探测器反应率计算结果的不确定度。结果表明,随屏蔽材料厚度的增加,不确定度逐渐增大;仅对截面协方差进行抽样时,弹性散射与非弹性散射截面协方差对快中子探测器反应率不确定度有较大影响,对1 Me V以上中子敏感的^(32)S(n,p)^(32)P探测器造成的不确定度最大达20%以上;此外,在同时考虑截面协方差与次级粒子角分布协方差后,不确定度量化结果会比仅考虑截面协方差时增加约2%。
基金The Project Supported by National Natural Science Foundation of China
文摘The K-shell ionization probability Pk was measured as a function of Ep across the strong resonance 56Fe(p,p)56Fe at 2.522 MeV and about 50 % variation was observed. For a large ratio of the K-shell binding energy to the total width of the nuclear resonance, Uk/Г≥5, the present experimental result is still in good agreement with theoretical calculation based on Blair and Anholt’s formula.
基金Supported by the Advanced Academy Special Foundation of Sanya under Grant No 2011YD14.
文摘Using the shell-model Monte Carlo method and random phase approximation theory,we carry out an estimation on neutrino energy loss(NEL)of ^(52,53,54,55,56)Fe.We find the NEL rates increase greatly at some typical stellar conditions,and even exceed eight orders of magnitude.On the other hand,in order to compare our results ofλ_(SMMC)^(LJ)(which are calculated by using the SMMC method)with those ofλ_(FFN)^(LJ)(which are calculated by using the Fuller-Fowler-Newman(FFN)method),the error factor C,betweenλ_(SMMC)^(LJ) andλ_(FFN)^(LJ),is discussed and shows that at higher density and temperature,the fit is fairly good for the two results(λ_(SMMC)^(LJ) andλ_(FFN)^(LJ)),and the maximum error is~6.20%.However,the maximum error is~95.50%(e.g.53Fe)at lower density and temperature.
文摘Ericson formula represents the first formula, which was suggested to describe the partial level density (PLD) formula in pre-equilibrium region of the nuclear reactions. Then a number of corrections were added to this formula in order to make it more suitable to physical meaning. In this paper, there are two aims to be done: the first aim is to study the correspondence between one and two-components formulae in Ericson, Pauli, and pairing corrections;the second aim is to compare and study the results of Comprehensive formula, which contents with all corrections, with Ericson, Pauli, and pairing formulae. The Comprehensive formula was suggested to simulate the reality. To achieve these aims the 56Fe and 90Zr nuclei were chosen and the results showed that the difference between one and two-components formulae was too small which can be neglected. Furthermore, the results strongly recommended that for cross section calculations of the nuclear reaction, one must use Comprehensive formula rather than Pauli formula.
基金supported by JSPS grants(Nos.24840021,18740318,23340152,25610148) from the Ministry of Education, Culture, Sports, Science and Technology, Japan
文摘The Ediacaran-Cambrian transition is characterized by numerous events such as the emergence of large multi-cellular metazoans and surface environmental disturbances.Based on geological evidence,it has been proposed that this transition coincided with the increase in the atmospheric oxygen level that was key to the evolution of life.Even though ancient redox conditions can be inferred from the composition of sedimentary iron mineral species,this method is not necessarily applicable to all rocks.In the Earth system,the cycling of iron is of considerable interest owing to its sensitivity to redox conditions.Information regarding the paleo-oceanic iron cycle is revealed in the iron isotopic composition of ironbearing minerals.Unfortunately,only limited iron isotopic data exists for Ediacaran-to Cambrianperiod oceans.To circumvent this deficiency,we drilled a fossiliferous Ediacaran to Early Cambrian sedimentary succession in the Three Gorges region,South China.We analyzed the iron isotope ratios(δ^(56/54)Fe)of pyrite grains in the drill cores using laser ablation multi collector inductively coupled plasma mass spectrometry.The results demonstrate large variations inδ^(56/54)Fe,from-1.6 to 1.6‰,and positive iron isotope ratios are observed in many successions.The presence of positiveδ^(56/54)Fe in pyrite indicates that the ferrous iron in the seawater was partially oxidized,suggesting that seawater at Three Gorges was ferruginous during the Ediacaran and Early Cambrian periods.However,aggregated pyrite grains in organic carbon-rich black shales at Member 4 of the Doushantuo Formation and the base of the Shuijingtuo Formation yield near-zeroδ^(56/54)Fe values;this suggests that the ocean was transiently dominated by sulfidic conditions during these periods.Notably negativeδ^(56/54)Fe values,lower than-1‰,can be interpreted as a signature of DIR.The DIR also might contribute in part to the re-mineralization of organic matter during the largest negative carbon isotope anomaly in the Ediacaran.
基金This work was supported by the National Natural Science Foundation of China(Grans No.50371098 and 50321101)the Key Project of the Beiing Science and Technology Program(Contract No.H02040030320).
文摘The Fe48Cr15Mo14Er2C15B6amorphous steel can hardly be used as an engineering material because of its ex- treme brittleness and very low iron content. By changing the composition of the nonmagnetic amorphous steel, and using the relation between the reduced glass transition tempera- ture Trg and the glass forming ability, a new amorphous Fe56Mn5Cr7Mo12Er2C12B6 alloy with good glass forming abil- ity and high iron content was obtained. The diameter of the as-cast sample rod reached 8 mm. This new amorphous steel has lower manufacturing cost due to its high iron content, and thus it can have wider applications.
