Oxide phosphors for light upconversion; Yb3+ and Tm3+ co-doped Y2BaZnO5

Copyright 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Journal of Applied Physics 109, 063104 (2011) and may be found at

Intestinal infection with Mycobacterium avium in acquired immune deficiency syndrome (AIDS)

At endoscopy, a 30-year-old man with acquired immune deficiency syndrome (AIDS), Kaposi's sarcoma, diarrhea, and unexplained malabsorption showed erythematous macular duodenal lesions consistent with Whipple's disease by histology and electron microscopy. Symptoms did not respond to tetracycline. Subsequent cultures revealed systemic Mycobacterium avium (M. avium) infection. Tissue from this patient, from patients with Whipple's disease and from a macaque with M. avium were compared. All contained PAS-positive macrophages but M. avium could be distinguished by positive acid-fast stains and a difference in pattern of indirect immunofluorescence staining with bacterial typing antisera. PAS-positive macrophages in the intestinal lamina propria are no longer pathognomonic of Whipple's disease. Ultrastructural and histological similarities between Whipple's disease and M. avium infection suggest that both are manifestations of immune deficits limiting macrophage destruction of particular bacteria after phagocytosis. M. avium must be considered in the differential diagnosis of diarrhea in patients with AIDS and other immunosuppressed conditions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44396/1/10620_2005_Article_BF01318186.pd

1.5 μm luminescence from ErQ based organic light emitting diodes

Organic light emitting diodes have been fabricated using erbium tris(8-hydroxy-quinoline) as the emitting layer and N, N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl- 4,4′-diamine (TPD) as the hole transporting layer. Room temperature electroluminescence was observed at 1.5 μm due to intra-atomic transitions between the 4I13/2 and 4I15/2 levels in the Er3+ ion. These results make the possibility of producing silicon compatible 1.5 μm technology based on such devices a reality

1.5 μm electroluminescence from organic light emitting diodes integrated on silicon substrates

We have produced a silicon based organic light emitting diode (OLED) which emits 1.5 μm electroluminescence at room temperature. The emitting layer used was erbium tris(8-hydroxyquinoline) and energy is transferred from excitons formed on the organic ligands into the erbium ion. Characteristic emission is observed through the silicon substrate at 1.5 μm due to the I to I intra-atomic transition. Whilst the device is not suited to conventional OLED applications, due to the long lifetime of the I to I transition, it is a significant step towards the development of a 1.5 μm laser which can be integrated onto a silicon waveguide. © 2001 Elsevier Science B.V

Time-resolved photoluminescence excitation characterisation of lanthanide and group III tris-(8-hydroxyquinoline) molecules

Time resolved photoluminescence measurements of lanthanide and group III metal chelates of 8-hydroxyquinoline (Q) have been performed as a function of temperature and excitation wavelength. For the lanthanide complexes it has been shown that either singlet or triplet luminescence can be observed depending on the excitation wavelength. Lifetime measurements of these emissions show that competing non-radiative paths are very important in the performance of these molecules. For ErQ we have shown that it is the singlet state that couples most efficiently to the ion. Radiative lifetime measurements of the ion emission show relatively short lifetimes that are indicative of quenching mechanisms. For the group III metal chelates at room temperature the luminescence is dominated by the singlet emission but at 80 K there is evidence that triplet emission can occur when the molecule is excited at long wavelengths. Luminescence lifetime measurements of the emission from the lanthanide ions: erbium, neodymium and ytterbium all show effective lifetimes of the order of microseconds which is very fast compared to the lifetimes of the free ions. Using excitation directly into the lanthanide ion (e.g. ~980 nm excitation for erbium) and via the organic ligands (~400 nm excitation) we have seen that there are no changes in the emission lifetimes and hence the exciton transfer from the ligand to the lanthanide ion is not a rate limiting step