Three possible structures of the favorable growth unit Al6（OH）<sup>18 （H2O）6 of gibbsite are calculated by ab initio at STO-3G, STO-3G*, STO-6G, STO-6G*, 3-21G, 6-31G levels and DFT at RB3LYP/3-21G, B3LYP/6-...Three possible structures of the favorable growth unit Al6（OH）<sup>18 （H2O）6 of gibbsite are calculated by ab initio at STO-3G, STO-3G*, STO-6G, STO-6G*, 3-21G, 6-31G levels and DFT at RB3LYP/3-21G, B3LYP/6-31G levels. The most excellent structure of Al6（OH）<sup>18 （H2O）6 （structure [A]） is confirmed. Based on these calculation results and considering efficiency factor, ab initio at STO-3G level is selected to optimize the structure [A]. The calculation results are compared with the experimental structure parameters of correlative systems. The total energy, orbital population and atomic charge of structure [A] are calculated using Dipole & Sphere solvent model at 6-31G, B3LYP/6-31G, 6-31G*, B3LYP/6-31G*, 6-31G** and B3LYP/6-31G** levels. The bonding orientation of Al6（OH）18（H2O）6 is analyzed.展开更多
The as-sintered sinter skin of WC-11Co-0.71Cr3C2-0.06RE cemented carbide with WC＋βmicrostructure was analyzed by scanning electron microscope, energy dispersive X-ray spectroscope and X-ray diffractometer. RE repres...The as-sintered sinter skin of WC-11Co-0.71Cr3C2-0.06RE cemented carbide with WC＋βmicrostructure was analyzed by scanning electron microscope, energy dispersive X-ray spectroscope and X-ray diffractometer. RE represents La-, Ce-, Pr- and Nd-containing mischmetal, andβis cobalt-based binder phase. It was discovered that La, Ce, Pr and Nd migrated directionally from the alloy to the sinter skin to combine with the impurity elements S and O from the sintering atmosphere during the sintering process. As a result, main dispersed phase RE2S3 and minor RE2O2S were formed in situ on the sinter skin. The mechanisms for the stimulation of the migration activity and the directional migration of RE atoms were discussed in terms of the thermodynamics stability of Cr3C2, solubility characteristic of Cr in Co and the polarization or ionization of RE atoms.展开更多
Sn-36%Ni peritectie alloys were directionally solidified at different growth rates under a constant temperature gradient （20 K/mm）, the dependences of microstructural characteristic length scales on the growth rate ...Sn-36%Ni peritectie alloys were directionally solidified at different growth rates under a constant temperature gradient （20 K/mm）, the dependences of microstructural characteristic length scales on the growth rate were investigated. Experimental results are presented, including primary and higher order dendrite arm spacings 21, 22, 23 and dendrite tip radius R of primary NisSn2 phase. Comparisons between the theoretical predictions and the experimental results show that, for the primary dendrites, 21=335.882v-0.21, which is in agreement with the Kurz-Fisher model; for the secondary dendrites, λ2=44.957v-0.277, which is consistent with the Bouchard-Kirkaldy model; for the tertiary dendrites, λ3=40.512v-0.274; for the dendrite tip radius, R=22.7v-0.36. The experimental results also show that the 21/22 changes greatly with increasing growth rate while the 21/23 has no significant change, indicating that tertiary dendrite arms have a more similar growth characteristics to primary dendrites compared with secondary dendrites. The λ1/R ranges from 2 to 2.3 with the increase of growth rate. Key words： Sn-Ni alloy; directional solidification; dendrite arm spacing; dendrite tip radius展开更多
Tin-based nanomaterials have been extensively explored as high-capacity anode materials for lithium ion batteries（LIBs）. However,the large volume changes upon repeated cycling always cause the pulverization of the e...Tin-based nanomaterials have been extensively explored as high-capacity anode materials for lithium ion batteries（LIBs）. However,the large volume changes upon repeated cycling always cause the pulverization of the electrode materials. Herein,we report the fabrication of uniform SnS_2@C hollow microspheres from hydrothermally prepared SnO_2@C hollow microspheres by a solid-state sulfurization process. The as-prepared hollow SnS_2@C microspheres with unique carbon shell,as electrodes in LIBs,exhibit high reversible capacity of 814 mA h g^（-1） at a current density of 100 mA g^（-1）,good cycling performance（783 mA h g^（-1） for 200 cycles maintained with an average degradation rate of 0.02% per cycle） and remarkable rate capability（reversible capabilities of 433 mA h g^（-1）at 2C）. The hollow space could serve as extra space for volume expansion during the charge-discharge cycling,while the carbon shell can ensure the structural integrity of the microspheres. The preeminent electrochemical performances of the SnS_2@C electrodes demonstrate their promising application as anode materials in the next-generation LIBs.展开更多
Endothelial cilia are microtubule-based hair-like protrusions in the lumen of blood vessels that function as fluid mechanosensors to regulate vascular hemodynamics. However, the functions of endothelial cilia in vascu...Endothelial cilia are microtubule-based hair-like protrusions in the lumen of blood vessels that function as fluid mechanosensors to regulate vascular hemodynamics. However, the functions of endothelial cilia in vascular development remain controversial. In this study, depletion of several key proteins responsible for ciliogenesis allows us to identify a cilium-independent role for intraflagellar transport 88(IFT88) in mammalian angiogenesis. Disruption of primary cilia by heat shock does not affect the angiogenic process. However, depletion of IFT88 significantly inhibits angiogenesis both in vitro and in vivo. IFT88 mediates angiogenesis by regulating the migration, polarization, proliferation, and oriented division of vascular endothelial cells. Further mechanistic studies demonstrate that IFT88 interacts with c-tubulin and microtubule plus-end tracking proteins and promotes microtubule stability. Our findings indicate that IFT88 regulates angiogenesis through its actions in microtubule-based cellular processes, independent of its role in ciliogenesis.展开更多
Deeply etched rib waveguides on silicon on insulator platform were not addressed well in research publications. We have analyzed single mode condition and polarization independence of a deeply etched rib waveguide （D...Deeply etched rib waveguides on silicon on insulator platform were not addressed well in research publications. We have analyzed single mode condition and polarization independence of a deeply etched rib waveguide （DE-RW） structure from biosensing perspective. With this rib structure, an asymmetrically etched integrated optic directional coupler has been numerically modeled to have the same coupling length for quasi- TE and TM modes. The coupling coefficients with the glucose solution as an upper cladding were calculated using a full vector mode solver, and the bulk refractive index sensitivity of the sensor was found as 28.305 × 10^-2/RIU for a fundamental quasi-TE mode.展开更多
文摘Three possible structures of the favorable growth unit Al6（OH）<sup>18 （H2O）6 of gibbsite are calculated by ab initio at STO-3G, STO-3G*, STO-6G, STO-6G*, 3-21G, 6-31G levels and DFT at RB3LYP/3-21G, B3LYP/6-31G levels. The most excellent structure of Al6（OH）<sup>18 （H2O）6 （structure [A]） is confirmed. Based on these calculation results and considering efficiency factor, ab initio at STO-3G level is selected to optimize the structure [A]. The calculation results are compared with the experimental structure parameters of correlative systems. The total energy, orbital population and atomic charge of structure [A] are calculated using Dipole & Sphere solvent model at 6-31G, B3LYP/6-31G, 6-31G*, B3LYP/6-31G*, 6-31G** and B3LYP/6-31G** levels. The bonding orientation of Al6（OH）18（H2O）6 is analyzed.
基金Project(51074189)supported by the National Natural Science Foundation of ChinaProject(2012ZX04003–021)supported by the National Science&Technology Special Foundation of ChinaProject(Y2012–010)supported by the Nonferrous Metals Research Foundation from Hunan Nonferrous Metals Holding Group Co.,Ltd.–CSU,China
文摘The as-sintered sinter skin of WC-11Co-0.71Cr3C2-0.06RE cemented carbide with WC＋βmicrostructure was analyzed by scanning electron microscope, energy dispersive X-ray spectroscope and X-ray diffractometer. RE represents La-, Ce-, Pr- and Nd-containing mischmetal, andβis cobalt-based binder phase. It was discovered that La, Ce, Pr and Nd migrated directionally from the alloy to the sinter skin to combine with the impurity elements S and O from the sintering atmosphere during the sintering process. As a result, main dispersed phase RE2S3 and minor RE2O2S were formed in situ on the sinter skin. The mechanisms for the stimulation of the migration activity and the directional migration of RE atoms were discussed in terms of the thermodynamics stability of Cr3C2, solubility characteristic of Cr in Co and the polarization or ionization of RE atoms.
基金Projects （51071062, 51271068, 51274077） supported by the National Natural Science Foundation of China Project （2011 -P03） supported by Open Fund of State Key Laboratory of Mold and Die Technology of Huazhong University of Science and Technology, China+1 种基金 Project （HIT. NSRIF. 2013002） supported by the Fundamental Research Funds for the Central Universities, China Project （2011CB610406） supported by the National Basic Research Program of China
文摘Sn-36%Ni peritectie alloys were directionally solidified at different growth rates under a constant temperature gradient （20 K/mm）, the dependences of microstructural characteristic length scales on the growth rate were investigated. Experimental results are presented, including primary and higher order dendrite arm spacings 21, 22, 23 and dendrite tip radius R of primary NisSn2 phase. Comparisons between the theoretical predictions and the experimental results show that, for the primary dendrites, 21=335.882v-0.21, which is in agreement with the Kurz-Fisher model; for the secondary dendrites, λ2=44.957v-0.277, which is consistent with the Bouchard-Kirkaldy model; for the tertiary dendrites, λ3=40.512v-0.274; for the dendrite tip radius, R=22.7v-0.36. The experimental results also show that the 21/22 changes greatly with increasing growth rate while the 21/23 has no significant change, indicating that tertiary dendrite arms have a more similar growth characteristics to primary dendrites compared with secondary dendrites. The λ1/R ranges from 2 to 2.3 with the increase of growth rate. Key words： Sn-Ni alloy; directional solidification; dendrite arm spacing; dendrite tip radius
基金supported by the National Natural Science Foundation of China (51302323)the Program for New Century Excellent Talents in University (NCET-13-0594)the Innovationdriven Project of Central South University (2017CX001)
文摘Tin-based nanomaterials have been extensively explored as high-capacity anode materials for lithium ion batteries（LIBs）. However,the large volume changes upon repeated cycling always cause the pulverization of the electrode materials. Herein,we report the fabrication of uniform SnS_2@C hollow microspheres from hydrothermally prepared SnO_2@C hollow microspheres by a solid-state sulfurization process. The as-prepared hollow SnS_2@C microspheres with unique carbon shell,as electrodes in LIBs,exhibit high reversible capacity of 814 mA h g^（-1） at a current density of 100 mA g^（-1）,good cycling performance（783 mA h g^（-1） for 200 cycles maintained with an average degradation rate of 0.02% per cycle） and remarkable rate capability（reversible capabilities of 433 mA h g^（-1）at 2C）. The hollow space could serve as extra space for volume expansion during the charge-discharge cycling,while the carbon shell can ensure the structural integrity of the microspheres. The preeminent electrochemical performances of the SnS_2@C electrodes demonstrate their promising application as anode materials in the next-generation LIBs.
基金supported by grants from the National Key R&D Program of China(2017YFA0503502)the National Natural Science Foundation of China(31730050,31871347,and 31900502)。
文摘Endothelial cilia are microtubule-based hair-like protrusions in the lumen of blood vessels that function as fluid mechanosensors to regulate vascular hemodynamics. However, the functions of endothelial cilia in vascular development remain controversial. In this study, depletion of several key proteins responsible for ciliogenesis allows us to identify a cilium-independent role for intraflagellar transport 88(IFT88) in mammalian angiogenesis. Disruption of primary cilia by heat shock does not affect the angiogenic process. However, depletion of IFT88 significantly inhibits angiogenesis both in vitro and in vivo. IFT88 mediates angiogenesis by regulating the migration, polarization, proliferation, and oriented division of vascular endothelial cells. Further mechanistic studies demonstrate that IFT88 interacts with c-tubulin and microtubule plus-end tracking proteins and promotes microtubule stability. Our findings indicate that IFT88 regulates angiogenesis through its actions in microtubule-based cellular processes, independent of its role in ciliogenesis.
文摘Deeply etched rib waveguides on silicon on insulator platform were not addressed well in research publications. We have analyzed single mode condition and polarization independence of a deeply etched rib waveguide （DE-RW） structure from biosensing perspective. With this rib structure, an asymmetrically etched integrated optic directional coupler has been numerically modeled to have the same coupling length for quasi- TE and TM modes. The coupling coefficients with the glucose solution as an upper cladding were calculated using a full vector mode solver, and the bulk refractive index sensitivity of the sensor was found as 28.305 × 10^-2/RIU for a fundamental quasi-TE mode.
