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- Khanin, Vasilii M., et al.
(författare)
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Influence of 3d Transition Metal Impurities on Garnet Scintillator Afterglow
- 2020
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Ingår i: Crystal Growth and Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 20:5, s. 3007-3017
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Tidskriftsartikel (refereegranskat)abstract
- Garnet scintillators often suffer from undesired afterglow, the origin of which is not always well-understood. A possible origin is contamination with transition metal (TM) ions. These impurities can act as traps giving rise to afterglow. Alternatively, they may show long-lived (microsecond) d-d emission. Here we present a systematic study on the role of 3d TM impurities in (Lu,Gd)3(GaAl)5O12 garnet scintillators. Scintillator disks intentionally doped with ppm levels of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn were studied to identify TM-related traps in thermoluminescence (TSL) glow curves and their role in afterglow. For Ti, V, and Cr additional TSL peaks were observed that gave rise to RT afterglow in the 10-2-103 s time range, depending on garnet composition. On the millisecond time scale long-lived red/near-infrared emission was observed from Mn and Fe impurities, explained by spin-forbidden d-d emission. We show that afterglow can be reduced by the use of ultrapure raw materials. Other solutions include bandgap engineering for the garnet host to modify trap depths and applying optical filters to block the spin-forbidden d-d emission. The present study provides an insightful overview of the role of 3d TM impurities on afterglow in Ce-doped scintillators and procedures to predict and reduce afterglow. These insights will aid the development of Ce-doped garnets with superior afterglow behavior.
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| 2. |
- Wang, Lu, et al.
(författare)
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Identification of a novel, recurrent HEY1-NCOA2 fusion in mesenchymal chondrosarcoma based on a genome-wide screen of exon-level expression data
- 2012
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Ingår i: Genes, Chromosomes and Cancer. - : Wiley. - 1045-2257. ; 51:2, s. 127-139
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Tidskriftsartikel (refereegranskat)abstract
- Cancer gene fusions that encode a chimeric protein are often characterized by an intragenic discontinuity in the RNA\expression levels of the exons that are 5' or 3' to the fusion point in one or both of the fusion partners due to differences in the levels of activation of their respective promoters. Based on this, we developed an unbiased, genome-wide bioinformatic screen for gene fusions using Affymetrix Exon array expression data. Using a training set of 46 samples with different known gene fusions, we developed a data analysis pipeline, the Fusion Score (FS) model, to score and rank genes for intragenic changes in expression. In a separate discovery set of 41 tumor samples with possible unknown gene fusions, the FS model generated a list of 552 candidate genes. The transcription factor gene NCOA2 was one of the candidates identified in a mesenchymal chondrosarcoma. A novel HEY1-NCOA2 fusion was identified by 5' RACE, representing an in-frame fusion of HEY1 exon 4 to NCOA2 exon 13. RT-PCR or FISH evidence of this HEY1-NCOA2 fusion was present in all additional mesenchymal chondrosarcomas tested with a definitive histologic diagnosis and adequate material for analysis (n = 9) but was absent in 15 samples of other subtypes of chondrosarcomas. We also identified a NUP107-LGR5 fusion in a dedifferentiated liposarcoma but analysis of 17 additional samples did not confirm it as a recurrent event in this sarcoma type. The novel HEY1-NCOA2 fusion appears to be the defining and diagnostic gene fusion in mesenchymal chondrosarcomas. (C) 2011 Wiley Periodicals, Inc.
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