نتایج جستجو برای: rare earth metal

تعداد نتایج: 514314  

Journal: :Science 2002
S J Mojzsis T M Harrison

Archean Quartzose Rocks at Akilia, Greenland Fedo and Whitehouse (1) presented data to support their hypothesis that granulite grade quartz magnetite rocks on the island of Akilia, southwest Greenland—which are conformably interposed with pyroxenite and hornblendite units that date from before 3830 million years ago (Ma) (2–4)—had a metasomatic ultramafic igneous origin. They offered that inter...

2017
Keith J. Dusoe Sriram Vijayan Thomas R. Bissell Jie Chen Jack E. Morley Leopolodo Valencia Avinash M. Dongare Mark Aindow Seok-Woo Lee

Bulk metallic glasses (BMGs) and nanocrystalline metals (NMs) have been extensively investigated due to their superior strengths and elastic limits. Despite these excellent mechanical properties, low ductility at room temperature and poor microstructural stability at elevated temperatures often limit their practical applications. Thus, there is a need for a metallic material system that can ove...

2002
A. P. Nutman

Archean Quartzose Rocks at Akilia, Greenland Fedo and Whitehouse (1) presented data to support their hypothesis that granulite grade quartz magnetite rocks on the island of Akilia, southwest Greenland—which are conformably interposed with pyroxenite and hornblendite units that date from before 3830 million years ago (Ma) (2–4)—had a metasomatic ultramafic igneous origin. They offered that inter...

2006
Masakatsu Shibasaki

Asymmetric catalysis is a powerful component of modern synthetic organic chemistry. To further broaden the scope and utility of asymmetric catalysis, new basic concepts for the design of asymmetric catalysts are crucial. Because most chemical reactions involve bond-formation between two substrates or moieties, high enantioselectivity and catalyst activity should be realized if an asymmetric cat...

2017
Chunxiang Wang Gen Luo Masayoshi Nishiura Guoyong Song Atsushi Yamamoto Yi Luo Zhaomin Hou

Heteroatom-functionalized polyolefins are of fundamental interest and practical importance. This has spurred investigations of the copolymerization of polar and nonpolar olefins. We report the first syndiospecific polymerization of a series of heteroatom-containing α-olefins and their copolymerization with ethylene catalyzed by half-sandwich rare-earth complexes. We have found that the interact...

Journal: :Journal of physics. Condensed matter : an Institute of Physics journal 2012
X F Wang X G Luo J J Ying Z J Xiang S L Zhang R R Zhang Y H Zhang Y J Yan A F Wang P Cheng G J Ye X H Chen

We successfully synthesized La- and Sm-doped phenanthrene powder samples and observed superconductivity in them at T(c) around 6 K. The T(c)s are 6.1 K for La(1) phenanthrene and 6.0 K for Sm(1) phenanthrene, which are enhanced by about 1 and 0.5 K compared to those in A(3) phenanthrene (A = K and Rb) and in Ae(1.5) phenanthrene (Ae = Sr and Ba) superconductors, respectively. The superconductiv...

Journal: :Dalton transactions 2014
Noa K Hangaly Alexander R Petrov Michael Elfferding Klaus Harms Jörg Sundermeyer

Reactions of Cp™HPPh2 (1, diphenyl(4,4,6,6-tetramethyl-1,4,5,6-tetrahydropentalen-2-yl)phosphane) with the organic azides AdN3 and DipN3 (Ad = 1-adamantyl; Dip = 2,6-di-iso-propylphenyl) led to the formation of two novel CpPN ligands: P-amino-cyclopentadienylidene-phosphorane (Cp™PPh2NHAd; L(Ad)H) and P-cyclopentadienyl-iminophosphorane (Cp™HPPh2NDip; L(Dip)H). Both were characterized by NMR sp...

2013
Shunzheng Zhao Honghong Yi Xiaolong Tang Shanxue Jiang Fengyu Gao Bowen Zhang Yanran Zuo Zhixiang Wang

Catalytic hydrolysis technology of carbonyl sulfide (COS) at low temperature was reviewed, including the development of catalysts, reaction kinetics, and reaction mechanism of COS hydrolysis. It was indicated that the catalysts are mainly involved metal oxide and activated carbon. The active ingredients which can load on COS hydrolysis catalyst include alkali metal, alkaline earth metal, transi...

2012
A. Simon

Structural frustration in a rod packing exhibits analogy to frustration effects in antiferromagnetic systems. Like the spins in a triangular Ising net, rods with periodic contour may arrange randomly. Such frustration effects are observed in rare earth metal carbide nitride halides composed of C2 centered RE6 octahedra and N centered RE4 tetrahedra. These can be connected in varying sequences t...

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