Double-resonance enhanced intersubband second-order nonlinear optical susceptibilities in GaN/AlGaN step quantum wells.

Second-order nonlinear optical susceptibilities for second harmonic generation (SHG) associated with intersubband transitions in GaN/AlGaN single quantum well and step quantum well have been studied theoretically by solving Schrödinger and Poisson equations self-consistently. The calculated results suggest that due to the very large polarization-induced field in the quantum well, the potential profile becomes asymmetrical, leading to large second-order susceptibilities. A high value about 4 × 10-7 m/V can be obtained in single quantum well structure. Furthermore, by adopting step quantum well structure to increase the asymmetry degree of the potential profile and manipulate the energy levels for double-resonance, a significant enhancement of second-order susceptibility can occur in step quantum well. Specifically, the susceptibility can be as large as 4 × 10-6 m/V with structure optimization, about an order of magnitude greater than that in single quantum well. The results indicate that nonlinear optical elements based on GaN/AlGaN step quantum wells are very promising for SHG in a wide range of wavelengths from telecommunication to mid-infrared, especially effective in longer wavelength.

[Chimeric perforator flap based on the descending branch of lateral circumflex femoral artery for tongue reconstruction after advanced tongue cancer resection].

Objective: To explore the advantages and clinical efficacy of free chimeric perforator flap based on the descending branch of circumflex femoral artery applied to tongue reconstruction after advanced tongue cancer resection. Methods: From October 2013 to December 2018, 57 cases received tongue and oral base reconstruction surgeries using the descending branch of circumflex femoral artery chimeric perforator flap, including 39 males and 18 females, ranged from 20 to 76 years old. And all cases were with stage T3 and T4 tongue cancers, including 35 cases of squamous cell carcinoma, 7 cases of low differentiation cancer, 5 cases of oncosarcoma, and 10 cases of adenoid cystic carcinoma. The tongue was reconstructed by using perforator flap and muscle flap to fill the dead space at the oral floor. The artery anastomoses with the superior thyroid artery or facial artery in the receiving area, and the vein anastomoses with the internal jugular vein in the receiving area. The shape, function and local complications of the reconstructed tongue were observed after operation. Results: Of 57 cases, only one case had partial necrosis of flap, while other 56 cases with chimeric perforator flap survived. Postoperative gastric tube and tracheal cannula were removed in all patients, no cases with oral fistula. All donor sites were sutured in one stage. Postoperative radiotherapy was performed in 41 of the patients. All patients were followed up for 3 to 60 months (average of 20.7 months), with satisfactory esthetic and functional results in reconstructed tongues. Only linear scars were left in the donor areas of the legs, and no lower limb dysfunction was observed. Conclusions: The descending branch of circumflex femoral artery chimeric perforator flap can used for repairing simultaneously the defects of both tongue and oral base. It is helpful to avoid the occurrence of oral fistula and to provide the reconstructed tongue with a good function. It is a good choice to use the descending branch of circumflex femoral artery chimeric perforator flap for tongue reconstruction after resection of advanced tongue cancer resection.

[Clinical and experimental studies of yuyang powder in treatment of peptic ulcer].

Two hundreds patients of peptic ulcer diagnosed by fiber-gastroscope treated with Yuyang powder (YYP) was observed and compared with patient treated with cimetidine for control. Results showed that the curative rate of YYP on peptic ulcer was 88.1%, the total effective rate was 96%, similar to that of cimetidine. But the difference of recurrence rate (19.1% for YYP and 46% for control) between the two groups was very significant. Animal experiment revealed that the protective action of YYP with high dosis on gastric mucosa in peptic ulcer and gastritis was superior to that of cimetidine, its has the double effect of both strengthening protective factors and weakening aggressive factors of gastric mucosa. Acute toxicologic test indicated that YYP has no toxic effect and was safe in clinical practice.