Modeling of negative Poisson’s ratio (auxetic) crystalline cellulose Iβ

Energy minimizations for unstretched and stretched cellulose models using an all-atom empirical force field (Molecular Mechanics) have been performed to investigate the mechanism for auxetic (negative Poisson’s ratio) response in crystalline cellulose Iβ from kraft cooked Norway spruce. An initial investigation to identify an appropriate force field led to a study of the structure and elastic constants from models employing the CVFF force field. Negative values of on-axis Poisson’s ratios nu31 and nu13 in the x1-x3 plane containing the chain direction (x3) were realized in energy minimizations employing a stress perpendicular to the hydrogen-bonded cellobiose sheets to simulate swelling in this direction due to the kraft cooking process. Energy minimizations of structural evolution due to stretching along the x3 chain direction of the ‘swollen’ (kraft cooked) model identified chain rotation about the chain axis combined with inextensible secondary bonds as the most likely mechanism for auxetic response

In-situ Computertomographie: Dimensionelles Messen und Materialprüfung an belasteten Bauteilen

Die Anwendung der Röntgen-Computertomographie (CT) als zerstörungsfreie Prüfung (zfP) entwickelt sich zunehmend zu einem unverzichtbaren bildgebenden Verfahren in der Qualitätssicherung. Seit dem letzten Jahrzehnt wird diese Technologie verstärkt auch in der dimensionellen Messtechnik eingesetzt

Magnetic Particle Imaging meets Computed Tomography: first simultaneous imaging

Magnetic Particle Imaging (MPI) is a promising new tomographic modality for fast as well as three-dimensional visualization of magnetic material. For anatomical or structural information an additional imaging modality such as computed tomography (CT) is required. In this paper, the first hybrid MPI-CT scanner for multimodal imaging providing simultaneous data acquisition is presented

Verbundprojekt zur Entwicklung der Technologie monolithisch integrierter Beschleunigungssensoren auf der Basis von Siliziummikromechanik Abschlussbericht

Available from TIB Hannover: F94B0078+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman