There is a special need to develop a dosimetry technique with a large-dynamic range and high-spatial resolution to characterize the microstructured X-ray beams used in microbeam radiation therapy (MRT) for cancer. We report the synthesis and characterization of oxyfluoride glass-ceramic (SiO 2 -Al 2 O 3 -CaF 2 -CaO-SmF 3 ) plates, which contain trivalent-samarium-doped calcium fluoride (CaF 2 :Sm 3+ ) nanocrystals, for use as a dosimetric detector material, particularly for MRT applications. Our approach utilizes the extent of Sm 3+ ?Sm 2+ valence reduction caused by X-ray irradiation as a probe of the X-ray dose delivered; and confocal fluorescent microscopy is used to read out the distribution of valence reduction through the photoluminescence (PL) signal. Our study showed that the Sm 3+ ?Sm 2+ valence reduction takes place in CaF 2 nanocrystals, but not in the glass matrix. The Sm 2+ shows PL emission predominantly due to the fast 4f 5 5d 1 ? 7 F 0 transition, which allows us to read out the detector plate at a high scanning speed. Further, our experiments showed that the detection dose range reaches several thousands of grays, and X-ray dose distribution is detected at a micrometer scale. In addition, the Sm 2+ signal can be erased either by heating the irradiated sample at a suitable high temperature or by exposing it to UV light; and the erased glass-ceramic plate is reusable. The new Sm-doped oxyfluoride glass-ceramic with CaF 2 nanocrystals reported in this work shows potential for practical use in highdose and high-resolution dosimetry for MRT.
J. McKittrick-contributing editorManuscript No. 34020.
The industrial sector of flexible printed electronics has shown a dynamic growth in the last decades. Therefore, demand for new inks, coatings and printing methods leading to improved performances of the electronic components at room temperature is also increasing. Here, we present a study on the conductive properties of silver layers obtained by different coating and printing methods. The results obtained proved that drop-on-demand inkjet printing of water-based inks containing micron-sized silver flakes with narrow-size distribution is a feasible method for in situ fabrication of conductive silver coatings that does not require additional heat treatment. A rigorous optimization Taguchi experiment was carried out considering the major process parameters. This experiment showed that the printing pressure was the dominant factor defining the quality of the printed coatings and tracks.
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