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951.
贾宝路 胡钧 何建军 许世伟 H.Yamaguchi D.Kahl 马朋 苏俊 王宏伟 T.Nakao Y.Wakabayashi T.Teranishi K.I.Hahn J.Y.Moon H.S.Jung T.Hashimoto A.A.Chen D.Irvine C.S.Lee S.Kubono 《原子核物理评论》2019,36(1):37-42
14O (α,p)17F是天体X射线暴中重要的突破反应。本工作通过厚靶方法测量其逆反应1H (17F,α)14O的反应截面来研究这一关键反应。本实验工作是在日本东京大学原子核科学研究中心(CNS)的低能次级束流线(CRIB)上完成的,后续的扣除本底实验是在兰州放射性束流线(RIBLL1)上完成的。CRIB实验是通过2H (16O,n)17F转移反应产生17F次级束,经过CRIB分离提纯之后,利用该次级束轰击氢气靶。在氢气靶后布置了三套望远镜探测器系统,用以探测不同实验角度的反冲α粒子,在数据处理的过程中经过动力学重构后得到了1H (17F,α)14O反应在质心系能区Ec.m.=2.7~3.4 MeV的反应截面。实验结果在3 MeV以上的高能区与前人的薄靶实验数据是一致的,在低能区本工作获得了新的实验数据,倾向于支持干涉相消的理论预言结果。The 14O(α, p)17F reaction is one of the important breakout reactions in type I X-ray burst. This work reported a new cross section measurement of its reverse reaction of 1H(17F,α)14O. The experiment was performed using the CNS radioactive ion beam separator (CRIB), located at the Center for Nuclear Study (CNS), the University of Tokyo. The sequent background measurement was carried out at Radioactive Beam Line in Lanzhou (RIBLL1). 17F beam was produced via the transfer reaction of 2H(16O, n)17F, subsequently separated and purified by CRIB and bombarded a thick hydrogen H2 gas target. The recoiling α particles were measured by three △E-E silicon telescopes at three different angles. The total cross sections of 1H(17F,α)14O have been derived at Ec.m.=2.7~3.4 MeV based on an isotropic angular distribution assumption. Our results are consistent with the previous ones in the energy region of Ec.m.>3 MeV, and we also obtained some new data in the low energy region, which partly support the destructive interference between the direct and resonant reaction mechanism predicted by the theory. 相似文献
952.
Wei‐Long Shan Yue‐Jian Lin F. Ekkehardt Hahn Guo‐Xin Jin 《Angewandte Chemie (International ed. in English)》2019,58(18):5882-5886
A series of molecular metalla[2]catenanes featuring Cp*Ir vertices have been prepared by the template‐free, coordination‐driven self‐assembly of dinuclear iridium acceptors and 1,5‐bis[2‐(4‐pyridyl)ethynyl]anthracene donors. The metalla[2]catenanes were formed by using a strategically selected linker type that is capable of participating in sandwich‐type π–π stacking interactions. In the solid state, the [2]catenanes adopt two different configurations depending on the halogen atoms at the dinuclear metal complex bridge. Altering the solvent or the concentration, as well as the addition of guest molecules, enabled controlled transformations between metalla[2]catenanes and tetranuclear metallarectangles. 相似文献
953.
954.
Le Zhang Rajorshi Das Chang‐Tao Li Yao‐Yu Wang F. Ekkehardt Hahn Kai Hua Li‐Ying Sun Ying‐Feng Han 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13494-13498
Metallosupramolecular poly‐NHC‐metal assemblies were prepared from trigonal hexakis (H6‐ 1 a (PF6)6 and H6‐ 1 b (PF6)6) or nonakis (H9‐ 3 (BF4)9) imidazolium salts and Ag2O. Complexes [Ag6( 1 a )2](PF6)6 and [Ag6( 1 b )2](PF6)6 are built from six Ag+ ions sandwiched between two trigonal hexacarbene ligands with an inner and an outer NHC donor in each of the three ligand arms. The metal atoms are arranged in two triangles. The hexakis‐NHC ligands bear cinnamic ester groups at the outlying NHC donors, used in postsynthetic [2+2] cycloaddition reactions linking two hexakis‐NHC ligands by three cyclobutane units to give complexes [Ag6( 2 a )](PF6)6 and [Ag6( 2 b )](PF6)6 bearing a dodecacarbene ligand. From the related nonakisimidazolium salt H9‐ 3 (BF4)9, complex [Ag9( 4 )](BF4)9 bearing an octadecacarbene ligand was obtained. Removal of the template metals yielded very large, stable, polyimidazolium cations with 12 or 18 internal imidazolium groups. 相似文献
955.
Strain-dependent deformation behavior in nanocrystalline metals 总被引:1,自引:0,他引:1
The deformation behavior as a function of applied strain was studied in a nanostructured Ni-Fe alloy using the in situ synchrotron diffraction technique. It was found that the plastic deformation process consists of two stages, undergoing a transition with applied strain. At low strains, the deformation is mainly accommodated at grain boundaries, while at large strains, the dislocation motion becomes probable and eventually dominates. In addition, current results revealed that, at small grain sizes, the 0.2% offset criterion cannot be used to define the macroscopic yield strength any more. The present study also explained the controversial observations in the literature. 相似文献
956.
Siegel Miles G. Shuker Athony J. Droste Christine A. Hahn Patrick J. Jesudason Cynthia D. McDonald III John H. Matthews Donald P. Rito Christopher J. Thorpe Andrew J. 《Molecular diversity》1997,3(2):113-116
A library of potential agonists and antagonists for adrenergic receptors was prepared using high-throughput solution-phase
parallel synthesis. Traditional solution-phase reductive amination reactions followed by rapid purification by ion exchange
chromatography yielded products with near-analytical purity. An array of ketones and amines, arranged in an 8 × 12 matrix,
were combined to form 96 individual compounds.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
957.
958.
The generation of metastable O2(1Σg+) and O2(1Δg) in the H + O2 system of reactions was studied by the flow discharge chemiluminescence detection method. In addition to the O2(1Σg+) and O2(1Δg) emissions, strong OH(v = 2) → OH(v = 0), OH(v = 3) → OH(v = 1), HO2(2A′000) → HO2(2A″000), HO2(2A′001) → HO2(2A″000), and H O2(2A″200) → HO2(2A″000) emissions were detected in the H + O2 system. The rate constants for the quenching of O2(1Σg+) by H and H2 were determined to be (5.1 ± 1.4) × 10?13 and (7.1 ± 0.1) × 10?13 cm3 s?1, respectively. An upper limit for the branching ratio to produce O2(1Σg+) by the H + HO2 reaction was calculated to be 2.1%. The contributions from other reactions producing singlet oxygen were investigated. 相似文献
959.
In this paper, we characterize the Hardy class ofM-harmonic functions on the unit ballB in ℂ
n
in terms of the Berezin transform. We define and study the Besovp-spaces ofM-harmonic functions. For anM-harmonic symbolf, we give various criteria for the Hankel operatorsH
f
andH
f
to be bounded, compact or in the Schatten-von-Neumann classS
p
. These criteria establish a close relationship among Besovp-spaces, Berezin transform, the invariant Laplacian, and Hankel operators on the unit ballB. 相似文献
960.