TY - JOUR A1 - Zabler, S. A1 - Riesemeier, Heinrich A1 - Fratzl, P. A1 - Zaslansky, P. T1 - Fresnel-propagated imaging for the study of human tooth dentin by partially coherent x-ray tomography N2 - Recent methods of phase imaging in x-ray tomography allow the visualization of features that are not resolved in conventional absorption microtomography. Of these, the relatively simple setup needed to produce Fresnel-propagated tomograms appears to be well suited to probe tooth-dentin where composition as well as microstructure vary in a graded manner. By adapting analytical propagation approximations we provide predictions of the form of the interference patterns in the 3D images, which we compare to numerical simulations as well as data obtained from measurements of water immersed samples. Our observations reveal details of the tubular structure of dentin, and may be evaluated similarly to conventional absorption tomograms. We believe this exemplifies the power of Fresnel-propagated imaging as a form of 3D microscopy, well suited to quantify gradual microstructural-variations in teeth and similar tissues. KW - Fourier optics KW - Partial coherence in imaging KW - Tomography KW - X-ray imaging KW - Phase modulation KW - Dentistry KW - High resolution Sy-CT KW - Microstructure in human Teeth PY - 2006 U6 - https://doi.org/10.1364/OE.14.008584 SN - 1094-4087 VL - 14 IS - 19 SP - 8584 EP - 8597 PB - Optical Society of America CY - Washington, DC AN - OPUS4-13869 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Paris, O. A1 - Li, C. A1 - Siegel, S. A1 - Weseloh, G. A1 - Emmerling, Franziska A1 - Riesemeier, Heinrich A1 - Erko, A. A1 - Fratzl, P. T1 - A new experimental station for simultaneous X-ray microbeam scanning for small- and wide-angle scattering and fluorescence at BESSY II N2 - A new instrument for simultaneous microbeam small- and wide-angle X-ray scattering and X-ray fluorescence (SAXS/WAXS/XRF) is presented. The instrument is installed at the microfocus beamline at BESSY II and provides a beam of 10 µm size with a flux of about 109 photons s-1. A SAXS resolution up to 500 Å d-spacing and a range of scattering vectors of almost three orders of magnitude are reached by using a large-area high-resolution CCD-based detector for simultaneous SAXS/WAXS. The instrument is particularly suited for scanning SAXS/WAXS/XRF experiments on hierarchically structured biological tissues. The necessary infrastructure, such as a cryo-stream facility and an on-site preparation laboratory for biological specimens, are available. KW - Scanning SAXS KW - Scanning WAXS KW - Microbeam KW - Synchrotron radiation PY - 2007 SN - 0021-8898 SN - 1600-5767 VL - 40 IS - Supplement SP - s466 EP - s470 PB - Blackwell CY - Oxford AN - OPUS4-15049 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Aichmayer, B. A1 - Wiedemann-Bidlack, F. B. A1 - Gilow, C. A1 - Simmer, J.P. A1 - Yamakoshi, Y. A1 - Emmerling, Franziska A1 - Margolis, H.C. A1 - Fratzl, P. T1 - Amelogenin nanoparticles in suspension: Deviations from spherical shape and pH-dependent aggregation N2 - It is well-known that amelogenin self-assembles to form nanoparticles, usually referred to as amelogenin nanospheres, despite the fact that not much is known about their actual shape in solution. In the current paper, we combine SAXS and DLS to study the three-dimensional shape of the recombinant amelogenins rP172 and rM179. Our results show for the first time that amelogenins build oblate nanoparticles in suspension using experimental approaches that do not require the proteins to be in contact with a support material surface. The SAXS studies give evidence for the existence of isolated amelogenin nano-oblates with aspect ratios in the range of 0.45-0.5 at pH values higher than pH 7.2 and show an aggregation of these nano-oblates at lower pH values. The role of the observed oblate shape in the formation of chain-like structures at physiological conditions is discussed as a key factor in the biomineralization of dental enamel. KW - Enamel KW - Recombinant amelogenin KW - rP172 KW - rM179 KW - Self-assembly KW - SAXS KW - DLS KW - Shape KW - Nanospheres KW - Oblates KW - pH dependency PY - 2010 U6 - https://doi.org/10.1021/bm900983b SN - 1525-7797 VL - 11 IS - 2 SP - 369 EP - 376 PB - ACS Publ. CY - Washington, DC, USA AN - OPUS4-20939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jungnikl, K. A1 - Goebbels, Jürgen A1 - Burgert, I. A1 - Fratzl, P. T1 - The role of material properties for the mechanical adaptation at branch junctions N2 - Branch junctions are mechanically particularly interesting areas of trees, because they have to withstand a combination of static and dynamic loads, from the stem as well as from the branch. In the present work, the local adaptation of material properties at branch junctions was assessed by mapping microfibril angle and tissue density. Images of the density distribution were obtained by computer tomography (CT). Wide angle X-ray scattering (WAXS) was used to determine the microfibril angle distribution with high-resolution around the junctions. The stem tissue around the junctions showed increased density and microfibril angle, which points towards an optimisation for fracture toughness. The tissue at the branch bases showed low density combined with high MFA, which provides deformability and flexibility and might act as protection of the stem against load transmission from the branch. KW - Branch junction KW - Computer tomography (CT) KW - Microfibril angle (MFA) KW - Notch stresses KW - Wide angle X-ray scattering (WAXS) PY - 2009 U6 - https://doi.org/10.1007/s00468-008-0305-9 SN - 0931-1890 VL - 23 IS - 3 SP - 605 EP - 610 PB - Springer CY - Berlin ; Heidelberg AN - OPUS4-22887 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schütz, Roman A1 - Bertinetti, L. A1 - Rabin, Ira A1 - Fratzl, P. A1 - Masic, A. T1 - Quantifying degradation of collagen in ancient manuscripts: the case of the Dead Sea Temple Scroll N2 - Since their discovery in the late 1940s, the Dead Sea Scrolls, some 900 ancient Jewish texts, have never stopped attracting the attention of scholars and the broad public alike, because they were created towards the end of the Second Temple period and the 'time of Christ'. Most of the work on them has been dedicated to the information contained in the scrolls' text, leaving physical aspects of the writing materials unexamined. They are, however, crucial for both historical insight and preservation of the scrolls. Although scientific analysis requires handling, it is essential to establish the state of degradation of these valued documents. Polarized Raman Spectroscopy (PRS) is a powerful tool for obtaining information on both the composition and the level of disorder of molecular units. In this study, we developed a non-invasive and non-destructive methodology that allows a quantification of the disorder (that can be related to the degradation) of protein molecular units in collagen fibers. Not restricted to collagen, this method can be applied also to other protein-based fibrous materials such as ancient silk, wool or hair. We used PRS to quantify the degradation of the collagen fibers in a number of fragments of the Temple Scroll (11Q19a). We found that collagen fibers degrade heterogeneously, with the ones on the surface more degraded than those in the core. KW - Dead Sea Scrolls KW - Collagen KW - Raman spectroscopy PY - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-331769 SN - 0003-2654 SN - 1364-5528 VL - 138 IS - 19 SP - 5594 EP - 5599 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-33176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -