Silica dispersion in styrene butadiene rubber composites studied by synchrotron tomography

By means of synchrotron X-ray computed tomography, model composites consisting of silica and styrene–butadiene rubber were studied with a very high spatial resolution. By our analysis technique we were able to determine the nano- and micro dispersion from the experimental results by our numerical analysis. These results are discussed with respect to crucial advantages of the generically 3-dimensional tomography technique as compared to 2-dimensional methods. Our quantitative analysis of the 3d images demonstrates that in the case of our model composites the filler dispersion is good, independent on the filler concentration. Our new 3-dimensional results evidence that considering only 2-d pictures may lead to ambiguities that can lead to wrong conclusions.     

The role of resonances in building cross sections: The Mittag‐Leffler expansion in a two‐channel scattering

The Mittag‐Leffler formalism for identifying resonance contributions to a two‐body scattering cross section is extended here from the one channel case to the two channel case. The reduced partial wave cross sections based on subtracting S‐matrix residues are compared with expressions which can be derived from the Breit‐Wigner approximation. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

Homogenisation method to capture the non-linear behaviour of intervertebral discs in multi-body systems

The present contribution is motivated by the desire to compute physiological loads on the intervertebral discs (IVD) of a human lumbar spine during activities like standing, bending and falling. Following this, a mechanical multi-body system (MBS) is utilised to capture the overall mechanical behaviour of a human, whereas an inhomogeneous, anisotropic, multi-phasic finite-element model (FEM) is applied to resolve the resulting field quantities inside an IVD. In order to couple the FEM of the IVD with the numerically diverse MBS, a homogenisation procedure has to be applied such that field quantities can be converted into discrete quantities. In particular, the MBS captures the mechanical behaviour of an IVD using a bushing element, which provides discrete force-displacement and moment-rotation relations. The goal of this contribution is to present a homogenisation method for the IVD as well as a possibility to include the homogenised results in the MBS without the need for embedded FE computations in the MBS. Instead, certain deformation modes of the IVD are pre-computed and represented using a non-linear constitutive equations. This task becomes even more challenging, as the resulting discrete DOF of a motion segment appear in a coupled fashion due to the structure of the IVD, i. e., a rotation in the sagittal plane triggers a resulting moment and a resulting force. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Analysis of glutathione adducts of patulin by means of liquid chromatography (HPLC) with biochemical detection (BCD) and electrospray ionization tandem mass spectrometry (ESI-MS/MS)

Abstract  A novel method for the identification of glutathione/electrophile adducts that are inhibiting glutathione-S-transferase (GST) activity was developed and applied for the analysis of the mycotoxin patulin. The method is based on high-performance liquid chromatography (HPLC) coupled to a continuous-flow enzyme reactor serving as biochemical detector (BCD) in parallel to electrospray mass spectrometric detection (ESI-MS). This HPLC-BCD technique combines a separation step and the detection of the inhibition and is therefore ideally suited for the analysis of the activity of single patulin/glutathione adducts within a complex mixture of adducts. Two out of at least 15 detected patulin–glutathione adducts showed strong GST inhibition. In ESI-MS, the inhibitory active adducts were characterized by [M + H]⁺ ions with m/z 462.1138 and m/z 741.2011, respectively. They could be identified as a dihydropyranone adduct containing one molecule glutathione and a ketohexanoic acid bearing two glutathione molecules. Graphical Abstract  OnlineAbstractFigure Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Anisotropic Operator Symbols Arising From Multivariate Jump Processes

It is shown that infinitesimal generators of certain multivariate pure jump Lévy copula processes give rise to a class of anisotropic symbols that extends the well-known classes of pseudo differential operators of H?rmander-type. In addition, we provide minimal regularity convergence analysis for a sparse tensor product finite element approximation to solutions of the corresponding stationary Kolmogorov equations . The computational complexity of the presented approximation scheme is essentially independent of the underlying state space dimension.