排序方式: 共有20条查询结果,搜索用时 15 毫秒
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MacArthur R Sazinsky MH Kühne H Whittington DA Lippard SJ Brudvig GW 《Journal of the American Chemical Society》2002,124(45):13392-13393
Spin-labeled Cys89 of the soluble methane monooxygenase regulatory protein (MMOB) from Methylococcus capsulatus (Bath) binds within 15 +/- 4 A of the hydroxylase (MMOH) diiron center, placing the MMOB docking site in the MMOH "canyon" region on iron-coordinating helices E and F of the alpha-subunit. 相似文献
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J. K. Brooks Kazuyuki Saitô JD Maitland Wright 《Rendiconti del Circolo Matematico di Palermo》2003,52(1):5-14
LetA be aC*-algebra with second dualA″. Let (φ
n)(n=1,...) be a sequence in the dual ofA such that limφ
n(a) exists for eacha εA. In general, this does not imply that limφ
n(x) exists for eachx εA″. But if limφ
n(p) exists whenever p is the range projection of a positive self-adjoint element of the unit ball ofA, then it is shown that limφ
n(x) does exist for eachx inA″. This is a non-commutative generalisation of a celebrated theorem of Dieudonné. A new proof of Dieudonné’s theorem, for
positive measures, is given here. The proof of the main result makes use of Dieudonné’s original theorem. 相似文献
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Elisabeth Hornberger Malte Klingenhof Shlomi Polani Paul Paciok Attila Kormnyos Raphaël Chattot Katherine E. MacArthur Xingli Wang Lujin Pan Jakub Drnec Serhiy Cherevko Marc Heggen Rafal E. Dunin-Borkowski Peter Strasser 《Chemical science》2022,13(32):9295
Recently proposed bimetallic octahedral Pt–Ni electrocatalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cell (PEMFC) cathodes suffer from particle instabilities in the form of Ni corrosion and shape degradation. Advanced trimetallic Pt-based electrocatalysts have contributed to their catalytic performance and stability. In this work, we propose and analyse a novel quaternary octahedral (oh-)Pt nanoalloy concept with two distinct metals serving as stabilizing surface dopants. An efficient solvothermal one-pot strategy was developed for the preparation of shape-controlled oh-PtNi catalysts doped with Rh and Mo in its surface. The as-prepared quaternary octahedral PtNi(RhMo) catalysts showed exceptionally high ORR performance accompanied by improved activity and shape integrity after stability tests compared to previously reported bi- and tri-metallic systems. Synthesis, performance characteristics and degradation behaviour are investigated targeting deeper understanding for catalyst system improvement strategies. A number of different operando and on-line analysis techniques were employed to monitor the structural and elemental evolution, including identical location scanning transmission electron microscopy and energy dispersive X-ray analysis (IL-STEM-EDX), operando wide angle X-ray spectroscopy (WAXS), and on-line scanning flow cell inductively coupled plasma mass spectrometry (SFC-ICP-MS). Our studies show that doping PtNi octahedral catalysts with small amounts of Rh and Mo suppresses detrimental Pt diffusion and thus offers an attractive new family of shaped Pt alloy catalysts for deployment in PEMFC cathode layers.PtNi nano-octahedra with Rh and Mo dopants are highly active catalysts for the oxygen reduction reaction with excellent stability and shape integrity. We investigate the morphological, structural, and compositional evolution during stability testing. 相似文献
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The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic field. At low densities we
use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained
from the relativistic nuclear mean field theory is taken and extended to include strong magnetic field. It is found that magnetized
neutron stars support higher maximum mass whereas the effect of magnetic field on radial stability for observed neutron star
masses is minimal. 相似文献
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Tyler H. Struzinski Lydia R. von Gohren Amy H. Roy MacArthur 《Transition Metal Chemistry》2009,34(6):637-640
Four known electronically diverse cobalt(II) acetylacetonate derivatives were synthesized by replacement of the acetylacetonate
methyl groups with combinations of tert-butyl, ethoxy, and trifluoromethyl groups in order to study the effect of catalyst electronic properties on the reaction
rate and product yield of the cobalt-catalyzed reaction between haloalkenes and butylzinc iodide. Infrared spectroscopy of
these compounds showed an increase in the CO stretching frequency as the ligand substituents became more electron withdrawing.
These compounds, in addition to cobalt(II) acetylacetonate itself, were evaluated as catalysts for the coupling reaction between
(E)-1-iodo-1-octene and butylzinc iodide to form (E)-5-dodecene. Faster reaction rates were observed and higher yields of 5-dodecene were produced when catalysts containing
electron-donating ligands were employed. Side reactions, including the homocoupling of 1-iodo-1-octene to produce 7,9-hexadecadiene,
were also observed under the reported reaction conditions. The rate of side-product formation was more competitive with the
rate of the cross-coupling reaction when slower, electron-deficient catalysts were employed. 相似文献
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Ben D. MacArthur Rubén J. Sánchez-García James W. Anderson 《Discrete Applied Mathematics》2008,156(18):3525-3531
We consider the size and structure of the automorphism groups of a variety of empirical ‘real-world’ networks and find that, in contrast to classical random graph models, many real-world networks are richly symmetric. We construct a practical network automorphism group decomposition, relate automorphism group structure to network topology and discuss generic forms of symmetry and their origin in real-world networks. We also comment on how symmetry can affect network redundancy and robustness. 相似文献