Enhancing the light-extraction efficiency is the key issue for realizing highly efficient AlGaN-based ultraviolet light-emitting diodes (UV-LEDs). We introduced several features to improve the light extraction: a transparent AlGaN:Mg contact layer, a Rh mirror electrode, an AlN template on a patterned sapphire substrate, and encapsulation resin. The combination of the AlGaN:Mg contact layer and the Rh mirror electrode significantly improved the output power and the external quantum efficiency (EQE) of UV-LEDs. By introducing the aforementioned features, a maximum EQE of >20% at an emission wavelength of 275 nm and a 20-mA direct current was achieved.

We demonstrated 256–278 nm AlGaN-based deep-ultraviolet (DUV) light-emitting diodes (LEDs) on Si substrates by using epitaxial lateral overgrowth (ELO) AlN templates. A 4-µm-thick ELO-AlN layer grown in a striped pattern along the <1010> direction can be coalesced successfully. Low-threading-dislocation-density AlN templates were achieved on Si wafers by a combination of the ELO and NH3 pulsed-flow multilayer growth methods. Single-peaked AlGaN LEDs with wavelengths shorter than 280 nm were achieved by fabricating them on ELO-AlN templates on Si. These low-cost AlGaN-based DUV LEDs on Si substrates are expected to be integrated on the same chips with Si-based electrical circuits.

Sodium niobate (NaNbO 3 , NN) thin films were deposited on (001)SrRuO 3 /Pt/MgO substrates by rf magnetron sputter deposition. The X-ray diffraction (XRD) pattern of the sputtered NN thin films showed epitaxial growth with a (001)-oriented perovskite structure. From the reciprocal space maps, the lattice parameters of the in-plane and out-of-plane directions were a ¼ 0:392 nm and c ¼ 0:395 nm, respectively. The relative dielectric constant " r and the range of the dielectric loss tan were about 270 and 0.05 -0.13 at 1 kHz, respectively. The P-E hysteresis loop showed clear ferroelectricity with spontaneous polarization P s of 20 mC/cm 2 and coercive electric field E c of 50 kV/cm. The transverse piezoelectric properties were evaluated from the tip displacement of NN/MgO unimorph cantilevers. The transverse piezoelectric coefficient e à 31 (¼ d 31 =s E 11 ) was À0:9 C/m 2 , which is almost compatible with that of the bulk NN ceramics. The tip deflection showed typical butterfly curves owing to the polarization reversal, indicating that the sputtered NN thin films had a high piezoelectric performance.

The purposes of this study were to determine whether a response shift was observable after partial denture treatment and to identify the predictors that influenced the response shift magnitude and direction. A total of 173 consecutive patients with no more than eight missing teeth who received implant-supported, fixed or removable partial dentures at Okayama University Dental Hospital were asked to complete a full-version Oral Health-Related Quality of Life (OHRQoL) questionnaire before (pre-test) and after treatment (post-test). Additionally, a short form (then-test) consisting of seven questions selected from the full version had its reliability verified and was utilised to retrospectively assess the pre-treatment OHRQoL status. The difference between the summary scores of the then-test and the pre-test determined the response shift magnitude and direction. The then-test mean score (22·9 ± 6·6) was significantly lower (worse OHRQoL) than that of the pre-test (26·4 ± 5·2). The response shift effect size was of moderate magnitude and negative direction (d = -0·78). A multiple regression analysis showed that age (younger patients) (P < 0·01), number of replaced teeth (fewer) (P < 0·01) and pre-test scores (lower) (P < 0·01) were the significant predictors for response shift. In conclusion, a response shift phenomenon with negative and moderate effect size was observed after partial denture treatment. The significant predictor variables were young age, fewer numbers of replaced teeth and lower pre-test scores.