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41.
Dipl.-Phys. W. Anders Cand. phys. D. Bastian Dr. E. Biller 《Zeitschrift für Physik A Hadrons and Nuclei》1969,224(1-3):113-121
Resonant magnetic field and linewidth of bulk nickel were determined between ?160 °C and room temperature at the frequencies of 9.2, 19.7 and 26.2 Gc/s. At 19.7 and 26.2 Gc/s the resonance-field shift is found to be proportional to the anisotropy field. Below ?90 °C the linewidth can be described by the independent-grain theory. For temperatures above ?90 °C the validity of the dipole-narrowing model is discussed. At 9.2 Gc/s resonance field and linewidth are strongly influenced by additional absorption peaks caused by domain structure. 相似文献
42.
43.
Alexandreas DE Allen RC Berley D Biller SD Burman RL Cady DR Chang CY Dingus BL Dion GM Ellsworth RW Gilra MK Goodman JA Gupta S Haines TJ Hoffman CM Krakauer DA Kwok P Lloyd-Evans J Lu XQ Nagle DE Potter ME Sandberg VD Stark MJ Talaga RL Vishwanath PR Yodh GB Zhang W 《Physical review D: Particles and fields》1991,43(5):1735-1738
44.
Harald Biller 《Geometriae Dedicata》2000,83(1-3):273-312
We establish sharp upper bounds for the dimensions of compact groups which act effectively on finite-dimensional compact generalized quadrangles with four-dimensional point rows. These bounds are attained, or indeed approached, only for explicitly known actions of Lie groups on Moufang quadrangles. 相似文献
45.
Dr. Xian-Juan Feng Dr. Matej Bobnar Swantje Lerch Harry Biller Dr. Marcus Schmidt Dr. Michael Baitinger Prof. Dr. Thomas Strassner Prof. Yuri Grin Dr. Bodo Böhme 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(50):12776-12787
The metastable type-II clathrate Na24-δGe136 was obtained from Na12Ge17 by applying a two-step procedure. At first, Na12Ge17 was reacted at 70 °C with a solution of benzophenone in the ionic liquid (IL) 1,3-dibutyl-2-methylimidazolium-bis(trifluoromethylsulfonyl) azanide. The IL was inert towards Na12Ge17, but capable of dissolving the sodium salts formed in the redox reaction. By annealing at 340 °C under an argon atmosphere, the X-ray amorphous intermediate product was transformed to crystalline Na24-δGe136 (δ≈2) and α-Ge in an about 1 : 1 mass ratio. The product was characterized by X-ray powder diffraction, chemical analysis, and 23Na solid-state NMR spectroscopy. Metallic properties of Na24-δGe136 were revealed by a significant Knight shift of the 23Na NMR signals and by a Pauli-paramagnetic contribution to the magnetic susceptibility. At room temperature, Na24-δGe136 slowly ages, with a tendency to volume decrease and sodium loss. 相似文献
46.
Dr. Xian-Juan Feng Swantje Lerch Harry Biller Dr. Maik Micksch Dr. Marcus Schmidt Dr. Michael Baitinger Prof. Dr. Thomas Strassner Prof. Yuri Grin Dr. Bodo Böhme 《ChemistryOpen》2021,10(2):205-215
Substituted imidazolium ionic liquids (ILs) were investigated for their reactivity towards Na12Ge17 as a model system containing redox-sensitive Zintl cluster anions. The ILs proved widely inert for imidazolium cations with a 1,2,3-trisubstitution at least by alkyl groups, and for the anion bis(trifluoromethylsulfonyl)azanide (TFSI). A minute conversion of Na12Ge17 observed on long-time contact with such ILs was not caused by dissolution of the salt-like compound, and did thus not provide dissolved Ge clusters. Rather, a cation exchange led to the transfer of Na+ ions into solution. In contrast, by using benzophenone as an oxidizer, heterogeneous redox reactions of Na12Ge17 were initiated, transferring a considerable part of Na+ into solution. At optimized conditions, an X-ray amorphous product NaGe6.25 was obtained, which was thermally convertible to the crystalline type-II clathrate Na24–δGe136 with almost completely Na-filled polyhedral cages, and α-Ge. The presented method thus provides unexpected access to Na24–δGe136 in bulk quantities. 相似文献
47.
Reinhold Tacke Rüdiger Bertermann Andreas Biller Olaf Dannappel Martin Penka Melanie Pülm Reiner Willeke 《无机化学与普通化学杂志》2000,626(5):1159-1173
The syntheses of the zwitterionic spirocyclic λ5Si‐silicates 7–14 are described. The chiral zwitterions contain a pentacoordinate (formally negatively charged) silicon atom and a tetracoordinate (formally positively charged) nitrogen atom, the ate and onium center being connected by an alkylene group. The zwitterions each contain two identical bidentate diolato(2–) ligands that formally derive from acetohydroximic acid or benzohydroximic acid. The stereochemistry and dynamic behavior of these compounds were investigated by experimental and theoretical methods. For this purpose, the zwitterionic λ5Si‐silicates 7–14 were studied by solution (1H, 13C, 29Si) and solid‐state (13C, 15N, and 29Si CP/MAS) NMR experiments. In addition, compounds 7 , 8 , 10 , 11 , and 13 were structurally characterized by single‐crystal X‐ray diffraction. The dynamic behavior (intramolecular enantiomerization) of 7 and 13 in solution was studied by VT 1H NMR experiments. These experimental studies were completed by ab initio investigations of the related anionic model species 15 . The chiral compounds 7–14 exist as (λ)‐ and (δ)‐enantiomers in the solid state and in solution. The trigonal‐bipyramidal structure of the respective Si‐coordination polyhedra, with the two carbon‐linked oxygen atoms in the axial sites, is the energetically most favorable one. The (λ)‐ and (δ)‐enantiomers of 7–14 are configurationally stable in solution on the NMR time scale ([D6]DMSO, room temperature). They undergo an intramolecular (λ)/(δ)‐enantiomerization (twist‐type mechanism), with an activation free enthalpy of δG{ = 72–73 kJ mol–1 (experimentally established for 7 and 13 ; calculated energy barrier for the model species 15 : 66.0 kJ mol–1). 相似文献
48.
Dr. Joshua R. Biller Dr. Mark Tseitlin Dr. Deborah G. Mitchell Zhelin Yu Laura A. Buchanan Dr. Hanan Elajaili Dr. Gerald M. Rosen Dr. Joseph P. Y. Kao Dr. Sandra S. Eaton Gareth R. Eaton 《Chemphyschem》2015,16(3):528-531
Radicals, including hydroxyl, superoxide, and nitric oxide, play key signaling roles in vivo. Reaction of these free radicals with a spin trap affords more stable paramagnetic nitroxides, but concentrations in vivo still are so low that detection by electron paramagnetic resonance (EPR) is challenging. Three innovative enabling technologies have been combined to substantially improve sensitivity for imaging spin‐trapped radicals at 250 MHz. 1) Spin‐trapped adducts of BMPO have lifetimes that are long enough to make imaging by EPR at 250 MHz feasible. 2) The signal‐to‐noise ratio of rapid‐scan EPR is substantially higher than for conventional continuous‐wave EPR. 3) An improved algorithm permits image reconstruction with a spectral dimension that encompasses the full 50 G spectrum of the BMPO–OH spin adduct without requiring the wide sweeps that would be needed for filtered backprojection. A 2D spectral–spatial image is shown for a phantom containing ca. 5 μM BMPO–OH. 相似文献
49.
50.
A synthesis of an advanced pentacyclic intermediate to the quinone antibiotic naphthyridinomycin (1) is described. The stereoselective synthesis of 2b from tricyclic lactam 31 features a regio- and stereoselective, intermolecular amidoalkylation reaction and a Friedel-Crafts ring closure to annelate the aromatic nucleus. 相似文献