Nanoscale CeAl4 was directly synthesized by the thermal reaction between CeH2 and nano-aluminum at300℃.Then nano CeAl4-doped sodium alanate（NaAlH4）was synthesized by ball milling NaH/Al with 0.04CeAl4under hydrogen...Nanoscale CeAl4 was directly synthesized by the thermal reaction between CeH2 and nano-aluminum at300℃.Then nano CeAl4-doped sodium alanate（NaAlH4）was synthesized by ball milling NaH/Al with 0.04CeAl4under hydrogen atmosphere at room temperature,and the catalytic efficiency of nanoscale CeAl4 for hydrogen storage of NaAlH4 was systematically investigated.It is shown that CeAl4 can effectively improve the dehydrogenation properties of sodium alanate system.The 0.04CeAl4-doped NaAlH4 system starts to release hydrogen below 80℃,completes dehydrogenation within 10 min at 170℃,and exhibits good cycling de/hydrogenation kinetics at relatively lower temperature（100-140℃）.Apparent activation energy of the dehydrogenation of NaAlH4 can be effectively reduced by addition of CeAl4,resulting in the decrease in desorption temperatures.Moreover,by analyzing the reaction kinetics of nano CeAl4-doped NaAlH4sample,both of the decomposition steps are conformed to a two-dimensional phase-boundary growth mechanism.The mechanistic investigations gained here can help to understand the de-/rehydrogenation behaviors of catalyzed complex metal hydride systems.展开更多
To improve the comprehensive mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy,different amount of Ce-rich rare earth(RE)was added to the alloy,and the effect of RE addition on the microstructure and mechanic...To improve the comprehensive mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy,different amount of Ce-rich rare earth(RE)was added to the alloy,and the effect of RE addition on the microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb alloy was investigated by means of Brinell hardness measurement, scanning electron microscopy(SEM),energy dispersive spectroscope(EDS)and X-ray diffraction(XRD).The results show that an appropriate amount of Ce-rich rare earth addition can make the Al4Ce phase particles and CeSb phase disperse more evenly in the alloy.These phases refine the alloy's matrix and make the secondary phases[?-Mg 32 (Al,Zn)49 phase and?-Al 2 Mg5Zn2 phase]finer and more dispersive,therefore significantly improve the mechanical properties of the Mg-10Zn-5Al-0.1Sb alloy.When the RE addition is 1.0 wt.%,the tensile strengths of the alloy both at room temperature and 150oC reach the maximum values while the impact toughness is slightly lower than that of the matrix alloy.The hardness increases with the increase of RE addition.展开更多
Although American libraries had begun collecting Chinese language materials in the 19th century, notably the United States Library of Congress in 1869, Yale in 1878, Harvard in 1879, and Berkeley in 1896, East Asian s...Although American libraries had begun collecting Chinese language materials in the 19th century, notably the United States Library of Congress in 1869, Yale in 1878, Harvard in 1879, and Berkeley in 1896, East Asian studies librarianship in North America, including China studies librarianship, was not fully developed until the 1960s. There was no formal organization that represented the interest of Chinese studies librarians because there were few of them and most of them were China scholars rather than trained librarians. More than 100 years later, the number of Chinese studies librarians in North America has increased considerably, primarily in response to the demand in the field of China studies and more recently to the needs of immigrant population and the general public who has an interest in China. This paper traces the history and growth of Chinese studies librarianship in North America, documents the development of the professional organization that represents Chinese studies librarians, and examines the training programs that prepare them for their jobs. It also attempts to propose an international exchange forum aiming to bring together Chinese studies librarians in North America and librarians in China in sharing their experience and expertise to achieve the ultimate goal of serving the users.展开更多
基金financially supported by the National High Technology Research&Development Program of China(No.2012AA051503)the National Natural Science Foundation of China(Nos.51171173 and 51471151)+2 种基金the China Postdoctoral Science Foundation(No.2012M521167)the Program for Innovative Research Team in University of Ministry of Education of China(No.IRT13037)the Zhejiang Provincial Science&Technology Program of China(Nos.2014C31134 and 2015C31035)
文摘Nanoscale CeAl4 was directly synthesized by the thermal reaction between CeH2 and nano-aluminum at300℃.Then nano CeAl4-doped sodium alanate（NaAlH4）was synthesized by ball milling NaH/Al with 0.04CeAl4under hydrogen atmosphere at room temperature,and the catalytic efficiency of nanoscale CeAl4 for hydrogen storage of NaAlH4 was systematically investigated.It is shown that CeAl4 can effectively improve the dehydrogenation properties of sodium alanate system.The 0.04CeAl4-doped NaAlH4 system starts to release hydrogen below 80℃,completes dehydrogenation within 10 min at 170℃,and exhibits good cycling de/hydrogenation kinetics at relatively lower temperature（100-140℃）.Apparent activation energy of the dehydrogenation of NaAlH4 can be effectively reduced by addition of CeAl4,resulting in the decrease in desorption temperatures.Moreover,by analyzing the reaction kinetics of nano CeAl4-doped NaAlH4sample,both of the decomposition steps are conformed to a two-dimensional phase-boundary growth mechanism.The mechanistic investigations gained here can help to understand the de-/rehydrogenation behaviors of catalyzed complex metal hydride systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.51001079,51044007,and 50571073)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20111402110004)the National Natural Science Foundation of Shanxi Province,China(Grant No.2009011028-3)
文摘To improve the comprehensive mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy,different amount of Ce-rich rare earth(RE)was added to the alloy,and the effect of RE addition on the microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb alloy was investigated by means of Brinell hardness measurement, scanning electron microscopy(SEM),energy dispersive spectroscope(EDS)and X-ray diffraction(XRD).The results show that an appropriate amount of Ce-rich rare earth addition can make the Al4Ce phase particles and CeSb phase disperse more evenly in the alloy.These phases refine the alloy's matrix and make the secondary phases[?-Mg 32 (Al,Zn)49 phase and?-Al 2 Mg5Zn2 phase]finer and more dispersive,therefore significantly improve the mechanical properties of the Mg-10Zn-5Al-0.1Sb alloy.When the RE addition is 1.0 wt.%,the tensile strengths of the alloy both at room temperature and 150oC reach the maximum values while the impact toughness is slightly lower than that of the matrix alloy.The hardness increases with the increase of RE addition.
文摘Although American libraries had begun collecting Chinese language materials in the 19th century, notably the United States Library of Congress in 1869, Yale in 1878, Harvard in 1879, and Berkeley in 1896, East Asian studies librarianship in North America, including China studies librarianship, was not fully developed until the 1960s. There was no formal organization that represented the interest of Chinese studies librarians because there were few of them and most of them were China scholars rather than trained librarians. More than 100 years later, the number of Chinese studies librarians in North America has increased considerably, primarily in response to the demand in the field of China studies and more recently to the needs of immigrant population and the general public who has an interest in China. This paper traces the history and growth of Chinese studies librarianship in North America, documents the development of the professional organization that represents Chinese studies librarians, and examines the training programs that prepare them for their jobs. It also attempts to propose an international exchange forum aiming to bring together Chinese studies librarians in North America and librarians in China in sharing their experience and expertise to achieve the ultimate goal of serving the users.
