[Case control study on anatomical locking plate and ordinary steel plate for the treatment of closed calcaneal fracture with Sandersâ ¡and â ¢].

OBJECTIVE: To compare clinical efficacy between anatomical locking plate (ALP) and ordinary steel plate (OSP) in treating closed calcaneal fractures with SandersⅡ and Ⅲ. METHODS: From May 2016 to May 2018, 68 patients with closed Sanders typeⅡ and Ⅲ calcaneal fractures were retrospectively analyzed, and were divided into anatomical locking plate group (ALP group) and ordinary steel plate group (OSP group) according to two kinds of plate fixation, and 34 patients in each group. In ALP group, there were 21 males and 13 females aged from 20 to 63 years old with average of (35.16±8.45) years old; 14 patients were typeⅡand 20 patients were type Ⅲaccording to Sanders classification;treated with ALP. In OSP group, there were 20 males and 14 females aged from 19 to 63 years old with average of (35.05±8.39) years old;19 patients were typeⅡand 15 patients were type Ⅲ according to Sanders classification;treated with OSP. Operative time, intraoperative blood loss and complications between two groups were observed and compared;preoperative and postoperative Böhler angle and gissane angle were also compared;American Orthopaedic Foot & Ankle Society (AOFAS) ankle and hind foot scores, foot and ankle disability index (FADI) scores were applied to evaluate clinical effect. RESULTS: All patients were followed up from 11 to 14 months with an average of (12.06±0.81) months. There were no statistical differences in opertive time, intraoperative blood loss, incision infection and refracture rate in complications between two groups (P>0.05);while there was significant difference in the number of screw loosening (P<0.05). Böhler angle and Gissane angle in ALP group at 6 and 12 months after opertaion were higher than that of OSP group (P<0.05), and the degree of improvement of Böhler angle and Gissane angle in ALP group were also higher than that of OSP group (P<0.05). Postopertaive AOFAS score and FADI score at 6 and 12 months in ALP group were higher than that of OSP group (P<0.05), while no statistical difference in AOFAS grading between two groups(P>0.05). CONCLUSION: Compared with OSP, ALP in treating SandersⅡ and Ⅲ calcaneal fractures could achieve better therapeutic effect, avoid screw loosening, reduce complications, and improve limb function in further.

[The electroluminescence spectra of InGan/GaN blue LEDs during aging time].

The luminescence spectra of InGaN/GaN multiple quantum wells light-emitting diodes under low level injection current (<4 mA) during aging process was investigated for the first time. Comparing the electroluminescence (EL) spectra of LEDs before and after aging time it was found that the peak wavelength and the full width at half maximum (FWHM) decreased with stress time and the changes of EL spectrum had two different stages-drastic decrease at the early stress stage and slow decrease later showing the same trend with the output optical power of LEDs, which indicates that the effective polarization electric field of LEDs becomes weak during the aging process and the change has a clear correlation with the increase of the defects in the multiple quantum wells of LEDs. Electrical measurement revealed that junction capacitance (C(j)) under the same junction voltage (V(j) = 1.8 V) and the junction voltage (V(j)) with the same injection current 1 mA calculated by ac small-signal IV method increased along with aging time, which explicates that the carrier density under the same low injection increases as the aging time increases. Analyses indicate that the polarization field in the quantum well is more seriously screened by the increased carriers captured by defects activated during stress time, the weaker effective polarization electric field makes the tilt of the energy band smaller, the energy radiated through the band edge and the density of energy states of the band edge increase which leads to the behaviors of peak wavelength and the FWHM of InGaN/GaN multiple quantum wells LEDs under low level injection current.

[Optical characteristics of InGaN/GaN light emitting diodes on patterned sapphire substrate].

In the present paper, optical characteristics of InGaN/GaN multiple quantum wells light emitting diodes fabricated on the conventional (C-LEDs) and patterned sapphire substrates (PSSLEDs) were investigated by electroluminescence (EL) and photoluminescence (PL). PSSLEDs show higher light output power and smaller full width at half maximum (FWHM) of EL than those of C-LEDs for their better crystalline quality. The FWHM of EL for PSSLEDs exhibits faster broadening as current increases than C-LEDs, while the same broadening of FWHM of PL as excitation power increases is shown in PSSLEDs and C-LEDs, which indicate that there is stronger band filling effect in PSSLEDs caused by relatively higher carrier density in their QWs at the same current injection level. Besides, smaller blue-shift of peak wavelength of EL as injection current increases in PSSLEDs suggests that piezoelectric field in PSSLEDs is weaker than that in C-LEDs. Therefore, comparing the changes in external quantum efficiency as current increases for PSSLEDs and C-LEDs, more serious efficiency droop for PSSLEDs could not be mainly caused by piezoelectric field in QWs.