ABSTRACT
A structured emission/excitation pattern, proper of isolated defects, arises in a vacuum from silica nanoparticles. The luminescence, centered around 3.0-3.5 eV, is characterised by a vibronic progression due to the phonon coupling with two localised modes of frequency â¼1370 cm(-1) and â¼360 cm(-1), and decays in about 300 ns at 10 K. On increasing the temperature, the intensity and the lifetime decrease due to the activation of a non-radiative rate from the excited state. Concurrently, the temperature dependence of the lineshape evidences the low coupling with non-localised modes of the matrix (Huang-Rhys factor S ~ 0.2) and the poor influence of the inhomogeneous broadening. These findings outline an uncommon behaviour in the field of the optical properties of defects in amorphous solids, evidencing that the silica surface can allocate luminescent defects almost disentangled from the basal network.
ABSTRACT
We analyzed the clinical and epidemiological data of 98 patients (50 males and 48 females) aged between 6 months and 16 years, hospitalized for Schönlein-Henoch syndrome in the last 20 years. The incidence was higher during spring time. Throat culture was positive for streptococcus pyogenes in 16% of patients. 14 of 60 (23%) had a positive allergometric response to various tests. The extrarenal manifestations were: purpura (100%), articular (68%) or gastrointestinal (32%) involvement and orchitis (10%). Renal symptoms were observed in 23% of the patients, but a clear nephropathy was documented just in 5% of the cases, with resolution within 2 years. Our data suggest, in agreement with the letterature, that renal involvement in Schönlein-Henoch syndrome has usually a benign course.
