Search Results

Now showing 1 - 10 of 449
  • Item
    Crystal structure of (2S,4S,7S)-7,7-dichloro-4-(1-chloro-1-methylethyl)-1- (2,2,2-trichloroethyl)bicyclo[4.1.0]heptane, C12H16Cl 6
    (Berlin : de Gruyter, 2009) Boualy, B.; el Firdoussi, L.; Ali, M.A.; Karim, A.; Spannenberg, A.
    C12H16Cl6, orthorhombic, P2 12121 (no. 19), a = 6.0742(3) Å, b = 9.7189(6) Å, c = 26.700(1) Å, V = 1576.2 Å3, Z = 4, Rgt(F) = 0.019, wRref(F2) = 0.045, T= 200 K. © by Oldenbourg Wissenschaftsverlag.
  • Item
    Mechanisms of bonding effected by nanoparticles in zirconia coatings applied by spraying of suspensions
    (Saarbrücke : Leibniz-Institut für Neue Materialien, 2008) Adam, Jens; Aslan, Mesut; Drumm, Robert; Veith, Michael
    Zirconia coatings consisting of a mixture of coarse and fine grained zirconia powders prepared by spraying of suspensions and subsequent thermal treatment at limited temperatures (up to 500°C) are poor in adherence and in intrinsic mechanical strength. We have shown elsewhere that mechanical properties of these coatings can be improved clearly by adding a small amount of nanoscaled zirconia. Here, the structural and the chemical development of this coating material and of the nanoparticles is examined to gain information about the underlying bonding mechanisms. The applied temperature is relatively low in comparison to the usual onset temperature of accelerated sintering. Nevertheless, the results show that diffusion controlled material transport mechanisms play their role in bonding. The condensation of surface OH groups may participate in bonding, too. These first results confirm the potential of nanoparticles to act as inorganic binder. Additional research effort to clarify the underlying mechanisms in detail is of interest. For the practical side, it can be concluded that the resulting effect of mechanical consolidation of ceramic structures at relatively low temperatures enables new ceramic applications, for example a new type of ceramic coatings on metallic substrates.
  • Item
    Adaptive Numerical Methods for PDEs
    (Zürich : EMS Publ. House, 2007) Süli, Endre; Verfürth, Rüdiger
    This collection contains the extended abstracts of the talks given at the Oberwolfach Conference on “Adaptive Numerical Methods for PDEs”, June 10th - June 16th, 2007. These talks covered various aspects of a posteriori error estimation and mesh as well as model adaptation in solving partial differential equations. The topics ranged from the theoretical convergence analysis of self-adaptive methods, over the derivation of a posteriori error estimates for the finite element Galerkin discretization of various types of problems to the practical implementation and application of adaptive methods.
  • Item
    Applications of Asymptotic Analysis
    (Zürich : EMS Publ. House, 2006) Palencia, E. Sanchez; Sokolowski, Jan; Wagner, Barbara
    This workshop focused on asymptotic analysis and its fundamental role in the derivation and understanding of the nonlinear structure of mathematical models in various fields of applications, its impact on the development of new numerical methods and on other fields of applied mathematics such as shape optimization. This was complemented by a review as well as the presentation of some of the latest developments of singular perturbation methods.
  • Item
    Arbeitsgemeinschaft: Percolation
    (Zürich : EMS Publ. House, 2007) van den Berg, Jacob; Camia, Federico
    Abstract. Percolation as a mathematical theory is more than fifty years old. During its life, it has attracted the attention of both physicists and mathematicians. This is due in large part to the fact that it represents one of the simplest examples of a statistical mechanical model undergoing a phase transition, and that several interesting results can be obtained rigorously. In recent years the interest in percolation has spread even further, following the introduction by Oded Schramm of the Schramm-Loewner Evolution (SLE) and a theorem by Stanislav Smirnov showing the conformal invariance of the continuum scaling limit of two-dimensional critical percolation. These results establish a new, powerful and mathematically rigorous, link between lattice-based statistical mechanical models and conformally invariant models in the plane, studied by physicists under the name of Conformal Field Theory (CFT). The Arbeitsgemeinschaft on percolation has attracted more than thirty participants, most of them young researchers, from several countries in Europe, North America, and Brazil. The main focus has been on recent developments, but several classical results have also been presented.
  • Item
    Increased biocompatibility and bioactivity after energetic PVD surface treatments
    (Basel : MDPI, 2009) Mändl, S.
    Ion implantation, a common technology in semiconductor processing, has been applied to biomaterials since the 1960s. Using energetic ion bombardment, a general term which includes conventional ion implantation plasma immersion ion implantation (PIII) and ion beam assisted thin film deposition, functionalization of surfaces is possible. By varying and adjusting the process parameters, several surface properties can be attuned simultaneously. Extensive research details improvements in the biocompatibility, mainly by reducing corrosion rates and increasing wear resistance after surface modification. Recently, enhanced bioactivity strongly correlated with the surface topography and less with the surface chemistry has been reported, with an increased roughness on the nanometer scale induced by self-organisation processes during ion bombardment leading to faster cellular adhesion processes. © 2009 by the authors;.
  • Item
    Arbeitsgemeinschaft mit aktuellem Thema: Twisted K-Theory
    (Zürich : EMS Publ. House, 2006) Freed, Dan; Schick, Thomas
    The “Arbeitsgemeinsschaft mit aktuellem Thema ‘Twisted KTheory’ ” gave an introduction to several aspects of twisted K-theory. It started with a couple of different definitions of twisted K-theory, suitable in situations of varying complexity from spaces to topological stacks. Then the AG presented tools of calculations like Chern characters with values in the corresponding twisted ordinary cohomology theories, and example calculations e.g. for Lie groups, or via T-duality. The program culminated in the theorem of Freed-Hopkins-Teleman calculating equivariant twisted K-theory of simple Lie groups in term of the Verlinde algebra of loop group representations.
  • Item
    Comparison of the molecular properties and morphology of polypropylenes irradiated under different atmospheres and after annealing
    (Hoboken, NJ [u.a.] : Wiley InterScience, 2006) Krause, Beate; Häußler, Liane; Voigt, Dieter
    Electron-beam irradiation, a well-known way of generating long-chain branching, was used to modify polypropylene. Samples were investigated with differential scanning calorimetry, polarized light microscopy, and size exclusion chromatography. Independently of the atmosphere, postannealing led to the deactivation of residual radicals and to the reduction of the nucleus density. In comparison with the initial polypropylene, the crystallization temperatures increased for nonannealed samples but decreased for annealed samples. Stable products were obtained only by irradiation in nitrogen followed by annealing. A reaction including free radicals with oxygen in the ambient atmosphere led to increasing molar mass degradation and the formation of long-chain branching after Storage. © 2006 Wiley Periodicals, Inc.
  • Item
    Dynamics of Patterns
    (Zürich : EMS Publ. House, 2008) Fiedler, Bernold; Sandstede, Björn
    This workshop focused on the dynamics of nonlinear waves and spatio-temporal patterns, which arise in functional and partial differential equations. Among the outstanding problems in this area are the dynamical selection of patterns, gaining a theoretical understanding of transient dynamics, the nonlinear stability of patterns in unbounded domains, and the development of efficient numerical techniques to capture specific dynamical effects.
  • Item
    Hilbert Modules and Complex Geometry
    (Zürich : EMS Publ. House, 2009) Eschmeier, Jörg; Upmeier, Harald
    The major topics discussed in this workshop were Hilbert modules of analytic functions on domains in ℂn, Toeplitz and Hankel operators, the interplay of commutative algebra, complex analytic geometry and multivariable operator theory, coherent and quasi-coherent sheaves as localizations of Hilbert modules, Hilbert bundles and Jordan varieties on Cartan domains.