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31.
Joachim Janssen Holger Rumpf Hartwig Modrow Ralf Rablbauer Georg Frommeyer Josef Hormes 《无机化学与普通化学杂志》2003,629(10):1701-1708
The surface oxidation of FeCr alloys with 18, 28, and 43 mass‐% Cr was investigated in situ using grazing‐incidence X‐ray absorption spectroscopy (GIXAS) at the chromium and iron K‐edges. Oxidation in air was monitored in situ in the temperature range from 290 K to 680 K. The standard GIXAS data analysis is extended for the treatment of a single layer model in order to estimate the chromium concentrations of the oxide layer and of the near‐interface substrate as well as the oxide layer thickness. XANES analysis shows transitions from b.c.c. Fe to corundum type Fe2O3 and from b.c.c. Cr to corundum type Cr2O3. The initial oxide layers are 1.1‐1.4 nm thick and contain 60‐90 mass‐% chromium, while the near‐interface substrate is depleted in Cr. During heating, iron oxide growth dominates up to 560‐600 K. Then the chromium oxide layer loses its passivation effect and Cr oxidation sets in. 相似文献
32.
Background
Hundreds of extracellular proteins polymerise into filaments and matrices by using zona pellucida (ZP) domains. ZP domain proteins perform highly diverse functions, ranging from structural to receptorial, and mutations in their genes are responsible for a number of severe human diseases. Recently, PLAC1, Oosp1-3, Papillote and CG16798 proteins were identified that share sequence homology with the N-terminal half of the ZP domain (ZP-N), but not with its C-terminal half (ZP-C). The functional significance of this partial conservation is unknown. 相似文献33.
Boskovic C Sieber A Chaboussant G Güdel HU Ensling J Wernsdorfer W Neels A Labat G Stoeckli-Evans H Janssen S 《Inorganic chemistry》2004,43(16):5053-5068
Nine members of a new family of polynuclear ferric complexes have been synthesized and characterized. The reaction of Fe(O(2)CMe)(2) with polydentate Schiff base proligands (H(2)L) derived from salicylidene-2-ethanolamine, followed in some cases by reaction with carboxylic acids, has afforded new complexes of general formulas [Fe(2)(pic)(2)(L)(2)] (where pic(-) is the anion of 2-picolinic acid), [Fe(3)(O(2)CMe)(3)(L)(3)], [Fe(4)(OR)(2)(O(2)CMe)(2)(L)(4)], and [Fe(5)O(OH)(O(2)CR)(4)(L)(4)]. The tri-, tetra-, and pentanuclear complexes all possess unusual structures and novel core topologies. M?ssbauer spectroscopy confirms the presence of high-spin ferric centers in the tri- and pentanuclear complexes. Variable-temperature magnetic measurements suggest spin ground states of S = 0, 1/2, 0, and 5/2 for the bi-, tri-, tetra-, and pentanuclear complexes, respectively. Fits of the magnetic susceptibility data have provided the magnitude of the exclusively antiferromagnetic exchange interactions. In addition, an easy-axis-type magnetic anisotropy has been observed for the pentanuclear complexes, with D values of approximately -0.4 cm(-)(1) determined from modeling the low-temperature magnetization data. A low-temperature micro-SQUID study of one of the pentanuclear complexes reveals magnetization hysteresis at nonzero field. This is attributed to an anisotropy-induced energy barrier to magnetization reversal that is of molecular origin. Finally, an inelastic neutron scattering study of one of the trinuclear complexes has revealed that the magnetic behavior arises from two distinct species. 相似文献
34.
Sieber A Boskovic C Bircher R Waldmann O Ochsenbein ST Chaboussant G Güdel HU Kirchner N van Slageren J Wernsdorfer W Neels A Stoeckli-Evans H Janssen S Juranyi F Mutka H 《Inorganic chemistry》2005,44(12):4315-4325
A new family of tetranuclear Ni complexes [Ni(4)(ROH)(4)L(4)] (H(2)L = salicylidene-2-ethanolamine; R = Me (1) or Et (2)) has been synthesized and studied. Complexes 1 and 2 possess a [Ni(4)O(4)] core comprising a distorted cubane arrangement. Magnetic susceptibility and inelastic neutron scattering studies indicate a combination of ferromagnetic and antiferromagnetic pairwise exchange interactions between the four Ni(II) centers, resulting in an S = 4 spin ground state. Magnetization measurements reveal an easy-axis-type magnetic anisotropy with D approximately -0.93 cm(-)(1) for both complexes. Despite the large magnetic anisotropy, no slow relaxation of the magnetization is observed down to 40 mK. To determine the origin of the low-temperature magnetic behavior, the magnetic anisotropy of complex 1 was probed in detail using inelastic neutron scattering and frequency domain magnetic resonance spectroscopy. The spectroscopic studies confirm the easy-axis-type anisotropy and indicate strong transverse interactions. These lead to rapid quantum tunneling of the magnetization, explaining the unexpected absence of slow magnetization relaxation for complex 1. 相似文献
35.
36.
37.
Hans-Karl Janssen 《Zeitschrift für Physik B Condensed Matter》1976,23(4):377-380
From the path probability density for nonlinear stochastic processes a Lagrangean for classical field dynamics is derived. This formulation provides a convenient approach to the mode coupling equations and the renormalization group theory of critical dynamics. An application is given for the time-dependent isotropic Heisenberg ferromagnet. The dynamical exponent
is derived aboveT
c for all dimensionsd>2. 相似文献
38.
Falko Böttger‐Hiller Patrick Kempe Dr. Gerhard Cox Dr. Alexander Panchenko Dr. Nicole Janssen Dr. Albrecht Petzold Prof. Dr. Thomas Thurn‐Albrecht Lars Borchardt Dr. Marcus Rose Prof. Dr. Stefan Kaskel Colin Georgi Prof. Dr. Heinrich Lang Prof. Dr. Stefan Spange 《Angewandte Chemie (International ed. in English)》2013,52(23):6088-6091
39.
R. A. J. Janssen D. Moses N. S. Sariciftci A. J. Heeger 《Molecular Crystals and Liquid Crystals》2013,570(1):921-926
Abstract Photoexcitation of a nonathiophene in film or solution across the π-π* energy gap produces a metastable triplet state. In the presence of C60, on the other hand, an ultra fast electron transfer from the photoexcited nonathiophene onto C60 is observed in films, whereas in solution C60 is involved in an efficient energy transfer reaction with the triplet-state nonathiophene. 相似文献
40.