BACKGROUND AND PURPOSE CT angiography (CTA) and MR angiography (MRA) are increasingly used methods for evaluation of stented vessel segments. Our aim was to compare CTA, contrast-enhanced MRA (CE-MRA) at 1.5T, and CE-MRA at 3T for the visualization of carotid artery stents and to define the best noninvasive imaging technique as an alternative to conventional angiography for each stent. MATERI...

GaN-based high-electron mobility transistors (HEMTs) with AlN/GaN super-lattices (SLs) (4 to 10 periods) as barriers were prepared on (0001) sapphire substrates. An innovative method of calculating the concentration of two-dimensional electron gas (2-DEG) was brought up when AlN/GaN SLs were used as barriers. With this method, the energy band structure of AlN/GaN SLs was analyzed, and it was fo...

Highly oriented (001) AlN (wurtzite type) thin films have been successfully deposited on silicon, platinized silicon and glass substrates by reactive radio-frequency magnetron sputtering at low temperature (150°C). X-ray diffraction, spectroscopic ellipsometry and scanning electron microscopy techniques have been employed to asses the structural characteristics of the AlN films. We have investi...

Double heterostructures of strained GaN quantum wells (QWs) sandwiched between relaxed AlN layers provide a platform to investigate the quantum-confined electronic and optical properties of the wells. The growth of AlN/GaN/AlN heterostructures with varying GaN quantum well thicknesses on AlN by plasma molecular beam epitaxy (MBE) is reported. Photoluminescence spectra provide the optical signat...

We experimentally demonstrated a free-standing two-dimensional (2-D) photonic crystal (PhC) aluminum nitride (AlN) membrane to function as a free space (or out-of-plane) reflector working in the mid infrared region. By etching circular holes of radius 620nm in a 330nm thick AlN slab, greater than 90% reflection was measured from 3.08μm to 3.78μm, with the peak reflection of 96% at 3.16μm. Due t...

Twist1 overexpression is involved in epithelial‑mesenchymal transition resulting in migration and metastasis of breast cancer. Carcinoma antigen 15‑3 (CA15‑3) is widely used to monitor the prognosis for patients after treatment. However, the significance of Twist1 in axillary lymph nodes (ALN) and CA15‑3 for co‑examination for survival rates remains to be elucidated. The present study aimed to ...

The capability of AlN nanostructures (nanocages, nanocones, nanotubes, and nanowires) to store hydrogen has been studied using gradient-corrected density functional theory. In contrast to bulk AlN, which has the wurtzite structure and four-fold coordination, the Al sites in AlN nanostructures are unsaturated and have two- and three-fold coordination. Each Al atom is capable of binding one H(2) ...

Due to large polarization effects, two-dimensional electron gas (2DEG) concentrations higher than 1x10 cm can be produced at the AlN/GaN heterojunction with AlN barriers as thin as 2 nm. This ultra-shallow channel together with the wide bandgap of AlN (6.2 eV) makes AlN/GaN heterojunction field effect transistors (HFET) extremely attractive for high frequency (>100 GHz) high power applications....

AlN epilayers were grown by metal organic chemical vapor deposition on sapphire substrates. X-ray diffraction measurements revealed that the threading dislocation TD density, in particular, the edge TD density, decreases considerably with increasing the epilayer thickness. Photoluminescence results showed that the intensity ratio of the band edge emission to the defect related emission increase...

High-density micro-circle patterned Si substrates were successfully fabricated for the direct overgrowth of thick AlN templates by using NH3 pulsed-flow multilayer AlN growth and epitaxial lateral overgrowth techniques. The experimental results show that an 8-μm-thick AlN template was grown at a very high growth rate on the substrates. The AlN template had full widths at half maximum of 0.23° a...