青铜小单孢菌(Micromonospora chalcea, M. chalcea)FIM 02-523能够合成对乏氧肿瘤细胞、艰难梭菌等具有活性的环脂肽类化合物rakicidins。利用Illumina HiSeq高通量测序平台,本研究首次对M. chalcea FIM 02-523进行全基因组测序,得到...青铜小单孢菌(Micromonospora chalcea, M. chalcea)FIM 02-523能够合成对乏氧肿瘤细胞、艰难梭菌等具有活性的环脂肽类化合物rakicidins。利用Illumina HiSeq高通量测序平台,本研究首次对M. chalcea FIM 02-523进行全基因组测序,得到总长约6.74Mb的序列信息。分析表明基因组GC含量为72.89%,包含了6167个蛋白编码序列。利用AntiSMASH预测基因组中存在19个生物合成基因簇。结合PKS/NRPS生物合成特征和rakicidins化学结构特点,定位到了rakicidins的生物合成基因簇,并初步推测其生物合成途径。研究为M. chalcea FIM 02-523的功能基因组学研究和代谢调控提供了理论基础。展开更多
By using AP-FIM the varity of the ordered degree of Ni_3Al with L1_2 structure with B content was studied. The possibility of boron improving ductility was also discussed from bonding between Ni and Al atoms, and anti...By using AP-FIM the varity of the ordered degree of Ni_3Al with L1_2 structure with B content was studied. The possibility of boron improving ductility was also discussed from bonding between Ni and Al atoms, and antisite defects in Ni_3Al. The extent of ordering is reduced with an increase in boron content and the autisite defects are most obvious for 0.52at.K B-doped sample that has the best ductility. Some results were verified by X-ray diffraction non. The addition of boron not only influences electron environment at grain boundary but also in the interior of Ni_3Al gm ins, the latter is favorable to improve the ductility of Ni_3Al grains.展开更多
The microstructures of TiAl intermetallic compounds prepared by ingot metallurgy and centrifugal spray deposition (CSD) were compared by field ion microscopy and atom probe (AP-FIM). The samples used have nearly stoi...The microstructures of TiAl intermetallic compounds prepared by ingot metallurgy and centrifugal spray deposition (CSD) were compared by field ion microscopy and atom probe (AP-FIM). The samples used have nearly stoichiometric composition of TiAl but there is Mn addition for ingot metallurgy (IM) samples and Mn and Nb additions for CSD samples. The field ion image of TiAl showed two regions of ordered f.c.t crystal structure (γ-TiAl) and disordered α-Ti3Al, and the distribution of Ti and Al atoms in TiAl alloy showed a lamellar structure which was confirmed by AP profiles. AP profiles showed that the major constituent of IM TiAl alloy is γ-TiAl with some Ti-rich regions. The compositions of these Ti-rich regions are nearly Ti3Al and Ti2Al from the calculation of AP data. The sample of CSD has a similar microstructure as compared with IM sample. The effects of alloying elements (Mn and Nb) on the ordering extent ,their distribution, and their sites occupied in the lattice were explored for both TiAl alloys. But there are no obvious Ti3Al or Ti2Al phases as shown in IM sample. In addition, the distributions of Mn and Nb concentrations in the CSD sample have a characteristic of wave form.展开更多
The purpose of the present work is to study the NiO cluster formation in Ni3Al alloys by field ion microscope and atom probe (AP-FIM). A polycrystal Ni3Al (B-doped) was heat-treated in atmospheres, the surface adsorpt...The purpose of the present work is to study the NiO cluster formation in Ni3Al alloys by field ion microscope and atom probe (AP-FIM). A polycrystal Ni3Al (B-doped) was heat-treated in atmospheres, the surface adsorption of air (hydrogen, oxygen) moisture etc.) occured on the Ni3Al surface and then these absorbents diffused into the interior of alloy through groin boundaries. AP-FIM studies found that the NiO and AlO clusters appeared in the local regions and amount of NiO clusters is much more than that of AlO. Moreover the hydrogen was simultaneously detected in the identical region.These results provided an experimental evidence that the formation of NiO and AlO clusters is the result of reaction of Ni (or Al) with residual moisture in Ni3Al, i.e. Ni+H2 O→NiO+2H. But the samples of B-free Ni3Al and B-doped single crystal Ni3Al have low concentration of NiO and H. This result shows that the diffusion of H2O molecule was promoted by genie boundaries containing boron. In addition, the boron suppresses environmental emvironmental was discussed, which suggested that the formation of Ni-O bonding has influence on bonding character of Ni-Al atoms and benefits the ductility of alloy.展开更多
文摘青铜小单孢菌(Micromonospora chalcea, M. chalcea)FIM 02-523能够合成对乏氧肿瘤细胞、艰难梭菌等具有活性的环脂肽类化合物rakicidins。利用Illumina HiSeq高通量测序平台,本研究首次对M. chalcea FIM 02-523进行全基因组测序,得到总长约6.74Mb的序列信息。分析表明基因组GC含量为72.89%,包含了6167个蛋白编码序列。利用AntiSMASH预测基因组中存在19个生物合成基因簇。结合PKS/NRPS生物合成特征和rakicidins化学结构特点,定位到了rakicidins的生物合成基因簇,并初步推测其生物合成途径。研究为M. chalcea FIM 02-523的功能基因组学研究和代谢调控提供了理论基础。
基金This project was supported by the National Nature Science Foundation of China!(Grant No.59831020 and 59895156)
文摘By using AP-FIM the varity of the ordered degree of Ni_3Al with L1_2 structure with B content was studied. The possibility of boron improving ductility was also discussed from bonding between Ni and Al atoms, and antisite defects in Ni_3Al. The extent of ordering is reduced with an increase in boron content and the autisite defects are most obvious for 0.52at.K B-doped sample that has the best ductility. Some results were verified by X-ray diffraction non. The addition of boron not only influences electron environment at grain boundary but also in the interior of Ni_3Al gm ins, the latter is favorable to improve the ductility of Ni_3Al grains.
基金the National Natural Science Foundation of China(Grant No.59831020)
文摘The microstructures of TiAl intermetallic compounds prepared by ingot metallurgy and centrifugal spray deposition (CSD) were compared by field ion microscopy and atom probe (AP-FIM). The samples used have nearly stoichiometric composition of TiAl but there is Mn addition for ingot metallurgy (IM) samples and Mn and Nb additions for CSD samples. The field ion image of TiAl showed two regions of ordered f.c.t crystal structure (γ-TiAl) and disordered α-Ti3Al, and the distribution of Ti and Al atoms in TiAl alloy showed a lamellar structure which was confirmed by AP profiles. AP profiles showed that the major constituent of IM TiAl alloy is γ-TiAl with some Ti-rich regions. The compositions of these Ti-rich regions are nearly Ti3Al and Ti2Al from the calculation of AP data. The sample of CSD has a similar microstructure as compared with IM sample. The effects of alloying elements (Mn and Nb) on the ordering extent ,their distribution, and their sites occupied in the lattice were explored for both TiAl alloys. But there are no obvious Ti3Al or Ti2Al phases as shown in IM sample. In addition, the distributions of Mn and Nb concentrations in the CSD sample have a characteristic of wave form.
基金The National Natural Science Foundation of China!(Grant No. 59831020)
文摘The purpose of the present work is to study the NiO cluster formation in Ni3Al alloys by field ion microscope and atom probe (AP-FIM). A polycrystal Ni3Al (B-doped) was heat-treated in atmospheres, the surface adsorption of air (hydrogen, oxygen) moisture etc.) occured on the Ni3Al surface and then these absorbents diffused into the interior of alloy through groin boundaries. AP-FIM studies found that the NiO and AlO clusters appeared in the local regions and amount of NiO clusters is much more than that of AlO. Moreover the hydrogen was simultaneously detected in the identical region.These results provided an experimental evidence that the formation of NiO and AlO clusters is the result of reaction of Ni (or Al) with residual moisture in Ni3Al, i.e. Ni+H2 O→NiO+2H. But the samples of B-free Ni3Al and B-doped single crystal Ni3Al have low concentration of NiO and H. This result shows that the diffusion of H2O molecule was promoted by genie boundaries containing boron. In addition, the boron suppresses environmental emvironmental was discussed, which suggested that the formation of Ni-O bonding has influence on bonding character of Ni-Al atoms and benefits the ductility of alloy.
