TY - JOUR A1 - Shipov, A. A1 - Zaslansky, P. A1 - Riesemeier, Heinrich A1 - Segev, G. A1 - Atkins, A. A1 - Kalish-Achrai, N. A1 - Weiner, S. A1 - Shahar, R. T1 - The influence of estrogen deficiency on the structural and mechanical properties of rat cortical bone N2 - Background. Post-menopausal osteoporosis is a common health problem worldwide, most commonly caused by estrogen deficiency. Most of the information regarding the skeletal effects of this disease relates to trabecular bone, while cortical bone is less studied. The purpose of this study was to evaluate the influence of estrogen deficiency on the structure and mechanical properties of cortical bone. Methods. Eight ovariectomized (OVH) and eight intact (control) Sprague Dawley rats were used. Structural features of femoral cortical bone were studied by light microscopy, scanning electron microscopy and synchrotron-based microcomputer-tomography and their mechanical properties determined by nano-indentation. Results. Cortical bone of both study groups contains two distinct regions: organized circumferential lamellae and disordered bone with highly mineralized cartilaginous islands. Lacunar volume was lower in the OVH group both in the lamellar and disorganized regions (182 ± 75 µm3 vs 232 ± 106 µm3 , P < 0.001 and 195 ± 86 µm3 vs. 247 ± 106 µm3 , P < 0.001, respectively). Lacunar density was also lower in both bone regions of the OVH group (40 ± 18 ×103 lacunae/mm3 vs. 47 ± 9×103 lacunae/mm3 in the lamellar region, P = 0.003 and 63 ± 18×103 lacunae/mm3 vs. 75 ± 13×103 lacunae/mm3 in the disorganized region, P < 0.001). Vascular canal volume was lower in the disorganized region of the bone in the OVH group compared to the same Region in the control group (P < 0.001). Indentation moduli were not different between the study groups in both bone regions. Discussion. Changes to cortical bone associated with estrogen deficiency in rats require high-resolution methods for detection. Caution is required in the application of These results to humans due to major structural differences between human and rat bone. KW - Estrogen KW - Disorganized bone KW - Rat KW - Lacunae KW - Ovariectomy PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520798 DO - https://doi.org/10.7717/peerj.10213 VL - 9 SP - e10213 AN - OPUS4-52079 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fretwurst, T. A1 - Buzanich, Günter A1 - Nahles, S. A1 - Woelber, J. P. A1 - Riesemeier, Heinrich A1 - Nelson, K. T1 - Metal elements in tissue with dental peri-implantitis: a pilot study N2 - Objectives: Dental peri-implantitis is characterized by a multifactorial etiology. The role of metal elements as an etiological factor for peri-implantitis is still unclear. The aim of this study was to investigate the incidence of metal elements in bone and mucosal tissues around dental Grade 4 CP titanium implants with signs of peri-implantitis in human patients. Methods: In this prospective pilot study, all patients were enrolled consecutively in two study centers. Bone and soft tissue samples of patients with peri-implantitis with indication for explantation were analyzed for the incidence of different elements (Ca, P, Ti, Fe) by means of synchrotron radiation X-ray fluorescence spectroscopy (SRXRF) and polarized light microscopy (PLM). The existence of macrophages and lymphocytes in the histologic specimens was analyzed. Results: Biopsies of 12 patients (seven bone samples, five mucosal samples) were included and analyzed. In nine of the 12 samples (75%), the SRXRF examination revealed the existence of titanium (Ti) and an associated occurrence with Iron (Fe). Metal particles were detected in peri- implant soft tissue using PLM. In samples with increased titanium concentration, lymphocytes were detected, whereas M1 macrophages were predominantly seen in samples with metal particles. Conclusion: Titanium and Iron elements were found in soft and hard tissue biopsies retrieved from peri-implantitis sites. Further histologic and immunohistochemical studies need to clarify which specific immune reaction metal elements/particles induce in dental peri-implant tissue. KW - Peri-implantitis KW - Metal elements KW - Synchrotron radiation X-ray fluorescence PY - 2016 DO - https://doi.org/10.1111/clr.12718 SN - 0905-7161 VL - 27 IS - 9 SP - 1178 EP - 1186 PB - WILEY-BLACKWELL CY - 111 RIVER ST, HOBOKEN 07030-5774, NJ USA AN - OPUS4-38641 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Arlt, Tobias A1 - Klages, M. A1 - Messerschmidt, M. A1 - Riesemeier, Heinrich A1 - Scholta, J. A1 - Banhart, J. A1 - Manke, I. T1 - Influence of artificial aging of gas diffusion layers on the water management of PEM fuel cells N2 - The influence of artificial aging of gas diffusion layers (GDL) on the water management within the GDL was investigated in-operando by synchrotron X-ray radiography. One GDL was subjected to an accelerated aging procedure in 30% H2O2 solution, while another GDL was pristine. Radiographic measurements were combined with temporally resolved electrical analyzes. Significant differences in cell voltage and water accumulation were observed during cell operation at steady-state conditions. The cell which contained the aged GDL featured a higher water amount especially at the anode side and a lower cell voltage. KW - Degradation KW - Liquid water PY - 2014 DO - https://doi.org/10.1149/2.004402eel SN - 2162-8726 VL - 3 IS - 2 SP - F7 EP - F9 PB - ECS CY - Pennington, NJ, USA AN - OPUS4-32410 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liu, Y. A1 - Schumacher, G. A1 - Riesemeier, Heinrich A1 - Banhart, J. T1 - Change in atomic coordination in a heavily deformed metallic glass N2 - The local structure around Ni and La atoms in Al85Ni10La5 amorphous powder after ball milling was investigated by X-ray absorption spectroscopy. A continuous decrease in coordination number of Ni and La as a function of milling time was observed, while the nearest neighbour distance and the mean square atomic displacement did not change, pointing at the creation of free volume around the Ni and La atoms. These structural changes resemble those of a liquid upon temperature increase. The results are described by a shear band model in which the coordination numbers of Ni and La are different within and outside a shear band. KW - X-ray-diffraction KW - Shear bands KW - Electron-irradiation KW - Positron lifetime KW - Structural model KW - Amorphous-alloys KW - Deformation KW - Temperature KW - EXAFS KW - State PY - 2014 DO - https://doi.org/10.1063/1.4879682 SN - 0021-8979 SN - 1089-7550 VL - 115 IS - 20 SP - 203510-1 EP - 203510-8 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-32409 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoch, H. A1 - Wessel, A. A1 - Asche, M. A1 - Baum, D. A1 - Beckmann, F. A1 - Bräunig, P. A1 - Ehrig, Karsten A1 - Mühlethaler, R. A1 - Riesemeier, Heinrich A1 - Staude, Andreas A1 - Stelbrink, B. A1 - Wachmann, E. A1 - Weintraub, P. A1 - Wipfler, B. A1 - Wolff, C. A1 - Zilch, M. T1 - Non-sexual abdominal appendages in adult insects challenge a 300 million year old bauplan N2 - Despite their enormous diversity, the bauplan of adult winged insects (pterygotes) is remarkably conservative since the Lower Devonian: a five-segmented head, a three-segmented thorax with three pairs of walking legs and an eleven-segmented abdomen without any non-sexual appendages 1 and 2. The only known exceptions are the abdominal appendages of adult male sepsid flies on the fourth segment; however, these are also used as copulatory organs and are supposedly maintained through sexual selection [3]. Here, we report a rod-like paired appendage from the third and fourth abdominal segments in adults of the Southeast-Asian Hemiptera taxon Bennini (Figure 1A,B; Supplemental information). These are fully musculated, innervated, and movable and bear highly organized sensory and secretory units. The appendages, termed LASSO (lateral abdominal sensory and secretory organs), are consistent in topology and structure in all species studied and not sexually dimorphic. The existence of these non-sexual abdominal appendages reveals the potential of the 300 million year old conserved bauplan of insects. KW - CT KW - Bauplan KW - Adult insects KW - Abdominal appendages PY - 2014 DO - https://doi.org/10.1016/j.cub.2013.11.040 SN - 0960-9822 SN - 1879-0445 VL - 24 IS - 1 SP - R16 EP - R17 PB - Cell Press CY - Cambridge, Mass. AN - OPUS4-30034 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rack, T. A1 - Zabler, S. A1 - Rack, A. A1 - Riesemeier, Heinrich A1 - Nelson, K. T1 - An in vitro pilot study of the abutment stability during loading in virgin and fatigue-loaded conical dental implants using synchrotron-based radiography N2 - Purpose: The implant-abutment connection of a two-piece dental implant exhibits complex micromechanical behavior. A microgap is evident at the implant-abutment interface, even in the virgin state, and its width varies when an external mechanical load is applied. Materials and Methods: This study used high-resolution synchrotron-based radiography in combination with hard x-ray phase-contrast mode to visualize this gap and estimate its size. Commercially available implants with different internal conical implant-abutment connections were imaged. Pairs of implants were imaged as manufactured (new) and after fatigue loading (5 million cycles up to 120 N). Then, different static loads were applied at different angles relative to the implant-abutment assemblies, and the implant-abutment microgaps were measured and compared. Results: Microgaps existed in all systems. Fatigue loading extended the size of the microgap and increased the possibility of micromovement of the implant-abutment complex. The cone angle of the connection also influenced the stability of the abutment, with flatter cones appearing to be more stable. Conclusion: Cyclic loading at medium force (120 N) induces plastic deformation of titanium implants and abutments. KW - Dental implants KW - Digital radiography KW - Phase-contrast microscopy KW - Synchrotron radiography KW - Titanium PY - 2013 DO - https://doi.org/10.11607/jomi.2748 SN - 0882-2786 SN - 1942-4434 VL - 28 IS - 1 SP - 44 EP - 50 PB - Quintessence Publ. Co. CY - Lombard, Ill. AN - OPUS4-30546 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shipov, A. A1 - Zaslansky, P. A1 - Riesemeier, Heinrich A1 - Segev, G. A1 - Atkins, A. A1 - Shahar, R. T1 - Unremodeled endochondral bone is a major architectural component of the cortical bone of the rat (Rattus norvegicus) N2 - The laboratory rat is one of the most frequently-used animal models for studying bone biology and skeletal diseases. Here we show that a substantial portion of the cortical bone of mature rats is primary endochondral bone, consisting of a disorganized arrangement of mineralized collagen fibers. We characterize the structure and mechanical properties of the cortical bone of the rat. We show that the cortical bone consists of two architecturally distinct regions. One region, consisting of well-organized circumferential lamellae (CLB), is located in the endosteal and/or the periosteal regions while another, disorganized region, is located in the more central region of the cortex. Unexpectedly, we found that the disorganized region contains many islands of highly mineralized cartilage. Micro tomography showed different structural and compositional properties of the two primary structural elements; the CLB region has lower mineral density, lower porosity, larger but fewer blood vessels and fewer lacunae. However, no difference was found in the average lacunar volume. Additionally the mean indentation modulus of the CLB region was lower than that of the disorganized region. The islands of calcified cartilage were found to be extremely stiff, with an indentation modulus of 33.4 ± 3.5 GPa. We conclude that though the cortical bone of rats is in part lamellar, its architecture is markedly different from that of the cortical bone of humans, a fact that must be borne in mind when using the rat as a model animal for studies of human bone biology and disease. KW - Cortical bone KW - Endochondral bone KW - Lamellar bone KW - Disorganized bone KW - Cartilage islands KW - Cortical bone structure KW - Synchrotron based microtomography KW - Mechanical properties PY - 2013 DO - https://doi.org/10.1016/j.jsb.2013.04.010 SN - 1047-8477 SN - 1095-8657 VL - 183 IS - 2 SP - 132 EP - 140 PB - Elsevier CY - San Diego, Calif. AN - OPUS4-30547 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zabler, S. A1 - Rack, A. A1 - Manke, I. A1 - Thermann, K. A1 - Tiedemann, J. A1 - Harthill, N. A1 - Riesemeier, Heinrich T1 - High-resolution tomography of cracks, voids and micro-structure in greywacke and limestone N2 - Rocks are commonly very heterogeneous materials. Randomly distributed micro-flaws inside the rock are believed to initiate tensile cracks from which shear fractures develop and coalescence through en echelon interactions leads to fracture. In this paper, we describe the results of applying high-resolution X-ray tomography to samples of greywacke and limestone experimentally deformed under unconfined axial shortening at various loads equivalent to different fractions of the sample strength. Mineral grains, pores, micro-cracks and other voids were imaged with a resolution of 10 µm. 3D image analysis enabled us to monitor the initial state of the samples and the changes in them due to compression. Crack morphology is characterized and compared to the micro-structure of the sample before and after deformation. In the greywacke, formation of a macro-crack ~10° oblique to the stress direction is observed. It initiated in fine intergranular material at the top tip of the sample and is composed of tensile fractures connected by wing cracks. None of the voids defined in the initial state fractured, and the crack is interpreted to have started either as a micro-crack which was smaller than the resolution of the tomography, or, as a completely new crack. In the limestone, cracks are observed to initiate in features that are too small to be imaged by the tomography, or also in newly created cracks. KW - Rock porosity KW - Crack formation KW - X-ray imaging KW - Micro-tomography KW - 3D image analysis PY - 2008 DO - https://doi.org/10.1016/j.jsg.2008.03.002 SN - 0191-8141 SN - 1873-1201 VL - 30 IS - 7 SP - 876 EP - 887 PB - Pergamon Press CY - Oxford AN - OPUS4-18566 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Danilewsky, A.N. A1 - Rack, A. A1 - Wittge, J. A1 - Weitkamp, T. A1 - Simon, R. A1 - Riesemeier, Heinrich A1 - Baumbach, T. T1 - White beam synchrotron topography using a high resolution digital X-ray imaging detector N2 - X-ray topography is a well known imaging technique to characterise strain and extended defects in single crystals. Topographs are typically collected on X-ray films. On the one hand such photographic films show a limited dynamic range and the production of films will be discontinued step by step in the near future. On the other hand new imaging detectors improved for X-ray tomography become more and more attractive even for topography because of increasing resolution, dynamic range, speed and active area. In this paper we report about the upgrade of the TOPO–TOMO beamline at the synchrotron light source ANKA, Research Centre Karlsruhe, with a high resolution digital camera for the topography use. KW - White beam topography KW - Synchrotron radiation KW - Digital X-ray detector KW - Scintillator KW - Synchrotron instrumentation KW - Digital radiography PY - 2008 DO - https://doi.org/10.1016/j.nimb.2008.02.065 SN - 0168-583X SN - 1872-9584 VL - 266 IS - 9 SP - 2035 EP - 2040 PB - Elsevier CY - Amsterdam AN - OPUS4-18567 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Arlt, Tobias A1 - Manke, I. A1 - Wippermann, K. A1 - Schröder, A. A1 - Mergel, J. A1 - Riesemeier, Heinrich A1 - Banhart, J. T1 - Röntgen-Kanten-Tomografie und -Radiografie zur Untersuchung von Alterungseffekten in Brennstoffzellenmaterialien KW - Resolution neutron-radiography KW - Local current distribution KW - Water transport KW - Carbon-dioxide KW - Methanol KW - Platinum KW - Oxidation PY - 2010 SN - 0025-5300 VL - 52 IS - 10 SP - 692 EP - 697 PB - Hanser CY - München AN - OPUS4-23045 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -