The Ba3MgSi2O8:Eu2+, Mn2+ shows three emission colors: 442, 505, and 620 nm. The 442 and 505 nm emission originate from Eu2+ ions, while the 620 nm emission originates from Mn2+ ions. The excitation bands of three emission colors are positioned around 375 nm. Electron paramagnetic resonance measurement demonstrates that Eu2+ ions are occupied with three different Ba2+ sites. The red emission of Mn2+ ions has a long decay time of 750 ms due to persistent energy transfer from oxygen vacancies to Mn2+ ions, while the blue and green bands of Eu2+ ions have decay times of 0.32 and 0.64 μs, respectively. The fabricated white-light emitting diode using a 400-nm-emissive chip with a white-light emitting Ba3MgSi2O8:Eu2+, Mn2+ phosphor shows warm white light and higher color stability against input power in comparison with a commercial GaN-pumped (Y1−xGdx)3(Al1−yGay)5O12:Ce3+ phosphor.

White-light-emitting diodes are fabricated by using 375nm emitting InGaN chip with Sr3MgSi2O8:Eu2+ (blue and yellow) or Sr3MgSi2O8:Eu2+, Mn2+ (blue, yellow, and red). At a color temperature of 5892K, the color coordinates are x=0.32, y=0.33, and the color rendering index is 84%; at a color temperature of 4494K, the color coordinates are x=0.35, y=0.33, and the color rendering index is 92%. The blue (470nm) and yellow (570nm) emission bands are originated from Eu2+ ions, while the red (680) emission band is originated from Mn2+ ions in Sr3MgSi2O8 host. The energy transfer among three bands occurs due to the spectral overlap between emission and absorption bands. It is confirmed by the faster decay time of the energy donor. Our white-light-emitting diodes show higher color reproducibility, higher color stability on forward-bias current, and excellent color rendering index in comparison with a commercial YAG:Ce3+-based white-light-emitting diode.

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We reviewed the MRI findings of germinomas originating from the basal ganglia, thalamus or deep white matter in 13 patients with 14 germinomas, excluding those in the suprasellar or pineal regions. Ten cases were confirmed as germinomas by stereotaxic biopsy, three by partial and one by total removal of the tumour. Analysis was focussed on the location and the signal characteristic of the tumour, haemorrhage, cysts within the tumour and any other associated findings. Thirteen of the tumours were in the basal ganglia and one in the thalamus. Haemorrhage was observed in seven patients, while twelve showed multiple cysts. Associated ipsilateral cerebral hemiatrophy was seen in three patients. The signal intensity of the parenchymal germinomas was heterogeneous on T1- and T2-weighted images due to haemorrhage, cysts and solid portions. We also report the MRI findings of germinomas in an early stage in two patients.

We investigated the interfacial electronic structures of indium tin oxide (ITO)/molybdenum trioxide (MoO3)/N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) using in situ ultraviolet and x-ray photoemission spectroscopy to understand the origin of hole injection improvements in organic light-emitting devices (OLEDs). Inserting a MoO3 layer between ITO and NPB, the hole injection barrier was remarkably reduced. Moreover, a gap state in the band gap of NPB was found which assisted the Ohmic hole injection at the interface. The hole injection barrier lowering and Ohmic injection explain why the OLED in combination with MoO3 showed improved performance.

BACKGROUND AND PURPOSE:Solitary fibrous tumor (SFT) is a rare spindle-cell neoplasm originating from mesenchymal fibroblast-like cells. The purpose of this study was to describe the CT and MR imaging features of SFTs in the orbit.

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The photoluminescence (PL) spectra of Ba3MgSi2O8:Eu2+ show one peak at 442 nm and two unresolved peaks at 505 nm. The 442 nm peak is attributed to the 4f→5d transition of the Eu2+ ion doped in the Ba2+(I) site with a weak crystal field, while the 505 nm peak originates from Eu2+ ions on the Ba2+(II) or the Ba2+(III) site with a strong crystal field. The PL spectra of the Sr2SiO4:Eu2+ show two emission peaks at 470 nm and 560 nm. The emission intensity at 470 nm decreases with increasing Eu2+ concentration, while that at 560 nm increases. This can be understood by considering the energy transfer from the 470 nm band to the 560 nm band through multipolar interaction. The GaN-based white-light-emitting diode (LED) fabricated using a mixture of Ba3MgSi2O8:Eu2+ and Sr2SiO4:Eu2+ phosphors has a broad-band spectrum, higher color rendering index and higher color stability against forward bias currents than Y3Al5O12:Ce3+-based white-LEDs.