ZnO nanorod arrays (ZNAs) were hydrothermally synthesized on the surface of patterned indium-doped tin oxide p-type contact (PIPC) of GaN-based light-emitting diodes (GaN-LEDs) for enhancing the light extraction efficiency (LEE). It was found that the alignment of the ZnO nanorod arrays in the grooves of the PIPC was poorer than these grown on the ridges of the PIPC. By comparing the light output of the GaN-LEDs with and without ZNAs grown in the grooves of PIPC, the influence of the alignment of ZNAs on the LEE of GaN-LEDs was revealed and investigated. Numerical analysis based on the finite difference of time domain (FDTD) method suggested that the poorer alignment of ZNAs grown on GaN-LEDs resulted in more energy reflected back into GaN-LEDs and lower light extraction efficiency.

Rationale: Intraspinal gout tophus in the lumbar vertebral canal associated with gouty arthritis is rare. We present 2 cases with the first manifestations of a sequestrated intervertebral disc and an extradural tumor, and histopathologically proven to be gouty deposits in the lumbar vertebral canal. Patient concerns: The 2 patients presented with typical radiculopathy symptoms and a positive straight leg raise. In 1 case, there was weakness of the left toe extensors, with a positive left femoral nerve traction test. Additionally, the left patellar tendon reflex was weak. In the other patient who was unable to walk, there was a sensory deficit in the saddle distribution. Diagnosis: Histopathological examination of the specimens taken from the operation confirmed the presence of gouty deposits. Interventions: Posterior decompression was performed in these 2 cases, and chalky-white materials were identified in the lumbar vertebral canal. Outcomes: No evidence of neoplasm, infection, or synovial cyst was found. Lessons: Definitive diagnosis of intraspinal extradural gout tophus, mimicking a sequestrated intervertebral disc or an extradural tumor, may be difficult. The initial suspicion of intraspinal gouty deposits, based on the diagnostic/management algorithm, may effectively avoid incorrect diagnosis via a less invasive procedure than explorative laminectomy.

We investigate the influence of size of ZnO nanorods on the light extraction efficiency (LEE) enhancement of GaN-based light-emitting diodes (GaN-LEDs). ZnO nanorods with different sizes are hydrothermally grown on patterned indium-doped tin oxide (ITO) electrodes of the GaN-LEDs in zinc acetate aqueous solutions of different concentrations. Measurements are conducted for the LEE enhancement of the LEDs with ZnO nanorods, compared to these without ZnO nanorods. The results suggest that the LEE of the LEDs with ZnO nanorods increases with the increasing size of ZnO nanorods. However, a saturation trend for the LEE improvement is also observed, which is attributed to the maximum limitation of light coupled into ZnO nanorods from GaN-based LEDs, and the reflection is increased by the increasing top surface of the ZnO nanorods.