Surface patterning of cemented carbides by means of nanosecond laser

A nanosecond laser combined with a two-axis reflection control unit is used to shape polygonal pyramids with defined geometry on a specific cemented carbide grade. In total, 12 different surface patterns have been fabricated, including four pyramid shapes, i.e., triangle, square, hexagon and octagon, and three lateral side angles, i.e., 30°, 45° and 60°. Characterization of the geometrical features shows satisfactory agreement between produced patterns and aimed ones. The precision is improved when the number of polygon sides and/or both side and slope angles increase. Side effects, such as re-deposition, cracks and pores, were discerned through scanning electron microscopy inspection. They become less obvious when the polygon side length or side angle increases, as the material melting becomes less important. Based on the observations, a borderline curve can be plotted for describing the production capability of such surface patterns on cemented carbides using the laser technologyPostprint (author's final draft

RADIOACTIVE EGFR ANTIBODY CETUXIMAB IN MULTIMODAL CANCER TREATMENT: STABILITY AND SYNERGISTIC EFFECTS WITH RADIOTHERAPY

Purpose: Systemic therapies when added to whole brain radiotherapy have failed to improve the survival of patient h multiple brain metastases. The epidermal growth factor receptor antibody cetuximab is an attractive option, if it is able to cross the blood-brain barrier. This might be proven with molecular imaging if the radiolabeled antibody is stable long enough to be effective. This study investigated the stability of radiolabeled cetuximab (Erbitux) ((131)I-Erbi) and potential synergistic effects with radiotherapy in vitro. Methods and Materials: Two cell lines were investigated, A431 with numerous epidermal growth factor receptors, and JIMT without epidermal growth factor receptors. We labeled 0.4 mg cetuximab with 50 MBq of [(131)I] iodide. Stability was determined for 72 h. The cell cultures were incubated with (131)I-Erbi or cold cetuximab for 72 h. Uptake and cell proliferation were measured every 24 h after no radiotherapy or irradiation with 2, 4, or 10 Gy. Results: The radiolabeling yield of (131)I-Erbi was always >80%. The radiochemical purity was still 93.6% after 72 h. A431 cells showed a (131)I-Erbi uptake about 100-fold greater than the JIMT controls. After 48 h, the A431 cultures showed significantly decreased proliferation. At 72 h after irradiation, (131)I-Erbi resulted in more pronounced inhibition of cell proliferation than the cold antibody in all radiation dose groups. Conclusion: (131)I-Erbi was stable for <= 72 h. Radiotherapy led to increased tumor cell uptake of (131)I-Erbi. Radiotherapy and (131)I-Erbi synergistically inhibited tumor cell proliferation. These results provide the prerequisite data for a planned in vivo study of whole brain radiotherapy plus cetuximab for brain metastases. (C) 2009 Elsevier Inc.German Research Society (DFG) [KFO 179

Surface patterning of cemented carbides by means of nanosecond laser

A nanosecond laser combined with a two-axis reflection control unit is used to shape polygonal pyramids with defined geometry on a specific cemented carbide grade. In total, 12 different surface patterns have been fabricated, including four pyramid shapes, i.e., triangle, square, hexagon and octagon, and three lateral side angles, i.e., 30°, 45° and 60°. Characterization of the geometrical features shows satisfactory agreement between produced patterns and aimed ones. The precision is improved when the number of polygon sides and/or both side and slope angles increase. Side effects, such as re-deposition, cracks and pores, were discerned through scanning electron microscopy inspection. They become less obvious when the polygon side length or side angle increases, as the material melting becomes less important. Based on the observations, a borderline curve can be plotted for describing the production capability of such surface patterns on cemented carbides using the laser technolog

Surface integrity assessment of laser treated and subsequently coated cemented carbides

Cemented carbides, referred to as hardmetals, are forefront engineering materials widely implemented in industry for chip-removal cutting tools and supporting parts. As a newly developed technology for surface modification with high precision, the application of short pulse laser may extend the utilization of cemented carbides. However, surface integrity of laser-treated materials may be affected during the ablation phenomena. These potential changes may also be relevant for subsequent coating deposition, a surface modification stage usually invoked in many cutting and forming tools. It is the objective of this work to study the influence of a previous laser treatment on the surface integrity of a cemented carbide grade, finally coated by a ceramic layer introduced by physical vapor deposition. In doing so, a nanosecond laser has been employed. Surface integrity is assessed in terms of roughness, hardness, and microstructural changes induced at the subsurface level. It is found that pulse laser can effectively remove the target material, resulting roughness being similar to that attained by abrasive grinding. Although some subsurface damage is observed, it is limited to a very shallow layer, this being thoroughly eliminated during sandblasting implemented before coating deposition. Relative hardness increase is larger for laser treated substrate than for just polished one, reason behind it being speculated to come from the sandblasting stage used for removing damaged layer.Peer Reviewe