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981.
In the paper methods for the coupling of different meshed local domains of a product model, which occur in an adaptivity process are compared. The properties of the applied coupling methods are demonstrated on finite element models from structural mechanics to point out the advantages and disadvantages of the methods in a model adaptivity process in the field of automotive engineering. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
982.
Sonja Herres Ulrich Flrke Gerald Henkel 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(12):m659-m660
The present structure determination of di‐μ‐hydroxo‐bis{[N,N′‐bis(dipiperidinomethylene)propane‐1,3‐diamine‐κ2N,N′]copper(II)} bis(hexafluorophosphate), [Cu2(OH)2(C25H46N6)2](PF6)2, is the first to crystallographically characterize a Cu2(μ‐OH)2 complex with a bidentate guanidine ligand. The cation lies on a crystallographic inversion centre and shows planar fourfold coordination of the copper centres. The Cu2(μ‐OH)2 species can be distinguished from Cu2(μ‐O)2 by the Cu—O bond lengths. The packing is determined by strong intermolecular anion–cation hydrogen bonds. 相似文献
983.
Marina M. Lezhnina Edgar Jordan Sergej A. Klimin Jürgen Löns Hubert Koller Boris N. Mavrin Ulrich Kynast Prof. Dr. 《无机化学与普通化学杂志》2009,635(3):450-455
In the course of investigations on optical properties resulting from the interaction of fluorides with alumosilicate host materials and rare earth guests, a well defined BF4– ion wasfound to be incorporated within the sodalite of composition Na8Al6Si6O24(BF4)2. The resulting cubic molecular structure, which was determined by Rietveld methods (space group P4 n, a = 906.91 pm, wRp = 0.045, Rp = 0.027), contains one anion in each sodalite cage and is, contrarily to expectations, thermally stable. NMR spectroscopic investigations indicated a fast rotatory motion of the BF4– tetrahedra at room temperature and agreed with the tetrahedral BF4– ions found in IR and Raman spectra. Preliminary attempts to obtain a luminescent material by incorporation of Eu3+ through aqueous ion exchange only yielded low rare earth concentrations, giving rise to characteristic red emission lines at 581 nm (5D0 → 7F1) and 615 nm (5D0 → 7F2) in a 1:2 intensity ratio. The material unexpectedly exhibited a strong broad band emission at 520 nm after calcination under Ar, which is attributed to the formation of an Eu2+ species. Further calcination under air partially reestablished the Eu3+ emission. 相似文献
984.
Janna Börner M. Sc. Ulrich Flörke Dr. Klaus Huber Prof. Dr. Artjom Döring Dipl.‐Chem. Dirk Kuckling Prof. Dr. Sonja Herres‐Pawlis Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(10):2362-2376
New class of air‐stable catalysts for lactide polymerisation: Guanidine–pyridine hybrid ligands (picture, left) were used to prepare a series of zinc complexes (e.g., depicted cation [ZnL2(CF3SO3)]+, where L is the quinoline‐containing ligand with R1=R2=R3=R4=Me), in which the ligand binds through two different N‐donor atoms. The zinc complexes show high activity in ring‐opening polymerisation of d,l ‐lactide (right), giving polylactide with molecular masses up to 176 000 g mol?1 and in high yield.
985.
Martin Hofmann Dr. Christine Höhn Frank W. Heinemann Dr. Ulrich Zenneck Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(24):5998-6007
Cage chirality : Cyclic addition reactions of chirally modified stannyl‐1,2,4‐triphospholes with tBuC?P leads to stannylated P5‐deltacyclenes in high yields as separable 1:1 mixtures of diastereomers. Destannylation of a separated diastereomer gives a single enantiomer of an optically pure P? C cage compound. The novel cage‐chiral P5C4 unit (shown here) dominates the chiroptical properties, not only of the isolated enantiomer, but of the diastereomeric compounds as well.
986.
Andreas Tengå Sven Lidin Prof. Jean‐Philippe Belieres Prof. Nathan Newman Prof. Yang Wu Ulrich Häussermann Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(27):6704-6710
Although free from structural disorder , the new intermetallic compound Cd13?xInySb10 (see figure) displays similarly low thermal conductivity values as disordered thermoelectric β‐Zn4Sb3 with an isostructural framework.
987.
Samples of the solid solution [ZnSnSb2]1−x[2(InSb)]x have been prepared over the whole range of composition by tin flux synthesis. The lattice parameter of the sphalerite-type average structure varies linearly between that of the end members ZnSnSb2 and InSb, a=6.2849(2) and 6.4776(15), respectively. Electron diffraction shows different kinds of structured diffuse scattering for Zn and In rich samples, respectively. The former is attributed to compositional short range ordering, the latter to thermally excited phonon modes. A metal-nonmetal transition takes place between the compositions x=0.8 and x=0.9. 相似文献
988.
A novel free-flow electrophoresis glass chip design with two-depth etched structures for the separation and fractionation of proteins is presented. The microfluidic structures etched in two depths enhance the flow characteristics inside the miniaturized device. A novel nine-port outlet interface enables the fractionation of the separated analytes. The separation and focussing of a protein sample mixture demonstrated the ability of the new chip. 相似文献
989.
Tae-Soo You Jing-Tai Zhao Rainer Pttgen Walter Schnelle Ulrich Burkhardt Yuri Grin Gordon J. Miller 《Journal of solid state chemistry》2009,182(9):2430-2442
Two isoelectronic series, Eu(Ga1−xTtx)2 (Tt=Si, Ge, 0≤x≤1), have been synthesized and characterized by powder and single-crystal X-ray diffraction, physical property measurements, and electronic structure calculations. In Eu(Ga1−xSix)2, crystal structures vary from the KHg2-type to the AlB2-type, and, finally, the ThSi2-type structure as x increases. The hexagonal AlB2-type structure is identified for compositions 0.18(2)≤x<0.70(2) with Ga and Si atoms statistically distributed in the polyanionic 63 nets. As smaller Si atoms replace Ga atoms while the number of valence electrons increases, the lattice parameters, unit cell volumes, and Ga–Si distances in this phase region decrease significantly. Although aspects of X-ray diffraction results suggest puckering of the 63 nets for the Si-richest example of the AlB2-type Eu(Ga1−xSix)2, the complete experimental evidence remains inconclusive. On the other hand, in Eu(Ga1−xGex)2, six different structural types were observed as x varies. In addition to EuGa2 (KHg2-type; space group Imma) and EuGe2 (own structure type, space group P3¯m1), the ternary phases studied show four different structures: the AlB2-type for Ga-rich compositions; the YPtAs-type structure for EuGaGe; and two new structures, which are intergrowths of the YPtAs-type EuGaGe and EuGe2, for Ge-rich compositions. These two Ge-rich phases include: (1) Eu(Ga0.45(2)Ge0.55(2))2 containing two YPtAs-type motifs of EuGaGe plus one EuGe2 motif; and (2) Eu(Ga0.40(2)Ge0.60(2))2 containing one YPtAs-type motif alternating with a split site at and z=0.4798(2) with ca. 50% site occupancy by Ga and Ge along the c-axis. Magnetic susceptibilities of three Eu(Ga1−xGex)2 compounds display Curie–Weiss behavior above ca. 100 K, and show effective magnetic moments indicative of divalent Eu with a 4f7 electronic configuration, consistent with. X-ray absorption spectra (XAS). Density of states (DOS) and crystal orbital Hamilton population (COHP) analyses, based on first principles electronic structure calculations, rationalize the observed homogeneity ranges of the AlB2-type phases in both systems and the structural variations as a function of Tt content. 相似文献
990.
Daan Wouters Dr. Stephanie Hoeppener Dr. Ulrich S. Schubert Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(10):1732-1739
Surfaces with purposes : The electroinitiated patterning of self‐assembled monolayers enables the fabrication of a variety of complex nanostructures (see picture). The possibilities offered by the introduction of chemical selectivity through the local generation of chemically active groups and subsequent derivatization are reviewed, with a focus on progress in this area of research over the last four years.