Perfectionism and adolescent sleep quality: The mediating role of repetitive negative thinking.

This study explores the mediating effects of repetitive negative thinking in the relationship between perfectionism and adolescent sleep quality. A sample of 1664 Chinese adolescents with a mean age of 15.0 years was recruited, and they completed four measures relating to perfectionism, sleep quality, worry, and rumination. The results showed that maladaptive perfectionism was positively correlated with poor sleep quality in adolescents, which was mediated by both worry and rumination. However, adaptive perfectionism was not significantly associated with adolescent sleep quality, and this relationship was suppressed by rumination (but not worry). The implications of these results are also discussed.

Luminescence studies on Ba2ZnSi2O7: Eu(2+) phosphors crystals.

A novel blue green-emitting phosphor, Ba2ZnSi2O7: Eu(2+), was prepared by combustion synthesis method and an efficient bluish green emission under from ultraviolet to visible light was observed. The emission spectrum shows a single intensive band centered at 503 nm, which corresponds to the 4f(6)5d(1) → 4f(7) transition of Eu(2+). The excitation spectrum is a broad band extending from 260 to 465 nm, which matches the emission of ultraviolet light-emitting diodes (UV-LEDs). The effect of doped Eu(2+) concentration on the emission intensity of Ba2ZnSi2O7: Eu(2+) was also investigated. The result indicates that Ba2ZnSi2O7: Eu(2+) can be potentially useful as a UV radiation-converting phosphor for white light-emitting diodes.

[Influence of Eu2+ content on the spectral characteristics of BaMgAl10O17 : Eu2+ phosphors].

Nanocrsytalline Ba(1-x)MgAl10O17 : xEu2+ (0.05 < or = x < or = 0.4) blue-emitting phosphor was successfully prepared by low-temperature combustion synthesis. The influence of different Eu content on the spectral characteristics of Ba(1-x) MgAl10O17 : xEu2+ was mainly investigated. The results of XRD and SEM analysis show that the sample is single phase and its average grain size is about 30 nm. The luminescence property of Ba(1-x)MgAl10O17 : xEu2+ phosphor is considerably influenced by Eu2+ concentration. In an appropriate Eu2+ doping concentration range, the intensity of the fluorescence of Ba(1-x)MgAl10O17 : xEu2+ was increased obviously with increasing the Eu2+ doping concentration, owing to adding the number of luminescent centers and enhancing the energy transfer between Eu2+ ions. The optimum emission intensity was reached at x = 0.2. However, as the Eu2+ doping concentration was higher than 0.2, the intensity of the fluorescence was reduced, due to the concentration quenching occurrence.