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Sapphire, belonging to hexagonal crystal system, is typically anisotropic which makes it direction-sensitive. To research the effects of growth directions on properties of sapphire, c-[0001] seed (c-sapphire) and a-[11-20] seed (a-sapphire) were used to prepare sapphire by edge-defined film-fed growth (EFG) method. The samples were analyzed through lattice integrity, dislocation and corrosion performance by double-crystal XRD, OM, AFM, SEM and EDX. It was shown that the lattice integrities of two growth-direction crystals were both well due to the small FWHM values. While the average densities of dislocation in c-sapphire and a-sapphire were 9.2×103 and 3.9×103 cm-2 respectively, the energy of dislocation in c-sapphire was lower than that in a-sapphire. During Strong Phosphoric Acid (SPA) etching, the surface of c-sapphire basically kept smooth but in a-sapphire there were many point-like corrosion pits where aluminum and oxygen atoms lost by 2:1. Our work means that it will be promising for growing c-[0001] seed sapphire by EFG if aided by parameter optimization.

Double glow plasma surface metallurgy technique was used to fabricate a Fe–Al–Cr–Nb alloyed layer onto the surface of the 45 steel. The microstructures and composition of the Fe–Al–Cr–Nb alloyed layer were analyzed by scanning electronic microscopy, X-ray diffraction and energy dispersive spectroscopy. The results indicate that the 20 μm alloyed layer is homogeneous and compact. The alloyed elements exhibit a gradient distribution along the cross section. Microhardness and nanoindentation tests imply that the surface hardness of the alloyed layer reaches HV 580, which is almost 2.8 times that of the substrate. Compared with the substrate, the alloyed layer has a much smaller displacement and a larger elastic modulus. According to the friction and wear tests at room temperature, the Fe–Al–Cr–Nb alloyed layer has lower friction coefficient and less wear mass, implying that the Fe–Al–Cr–Nb alloyed layer can effectively improve the surface hardness and wear resistance of the substrate.

Objective To determine the site(s) of upper airway obstruction in patients with obstructive sleep apnea syndrome (OSAS) and their changes during sleep with upper airway (UA) pressure measurement; and to analyze the correspondence between the UA pressure measurement and polysomnography (PSG). Method Thirty patients with OSAS underwent UA pressure measurement. The catheter with five solid-state ultraminiature sensors was inserted through the patients' upper airway to the esophagus. The sensors were located at the nasopharynx, oropharynx, tongue base, hypopharynx, and esophagus. The lower limit of UA obstruction was determined by relying on the observed pressure pattern. Result 1) During inspiration, obstruction occurred associated with an increased negative inspiratory pressure inferior to the site of obstruction and a disappeared negative inspiratory pressure above the site of obstruction; 2) three patterns of obstruction were observed; 3) the site of obstruction was located at the site of the palate; 4) velopharyngeal obstruction and tongue–pharynx obstruction were all present; 5) nasopharyngeal obstruction velopharyngeal obstruction and tongue–pharynx obstruction were all present; and 6) peak inspiratory pressure differences between the normal breath and apnea were associated with the longest apnea interval (P