Articles you may be interested inDiffusion of Mg dopant in metal-organic vapor-phase epitaxy grown GaN and AlxGa1−xN Reduction of Mg segregation in a metalorganic vapor phase epitaxial grown GaN layer by a low-temperature AlN interlayer J. Appl. Phys.

A detailed transmission electron microscopy study of pyramidal defects appearing in highly Mg-doped GaN is reported. It is shown that these defects are closed pyramidal inversion domains. From a high-resolution microscopy study, we propose atomic models for inversion domain boundaries which consist of Mg 3 N 2 building blocks for both the basal and inclined facets of the pyramids. In Mg-doped GaN grown by metalorganics vapor phase epitaxy, these pyramidal inversion domains are a few nanometers wide, and their density is high enough to play a role in the free hole density decrease at high Mg doping.

In vitro, Helicobacter pylori converts from a bacillary to a full coccoid form via an intermediate U-shaped form. Organisms with a full coccoid form keep a double membrane system, a polar membrane, and invagination structures. Western blots (immunoblots) of sera from colonized patients show that some high-molecular-mass antigenic fractions are expressed only in coccoids. Conversely, fractions of 30 and 94 kDa were more intensively detected in the bacillary forms. These results suggest that (i) coccoid conversion is not a degenerative transformation and (ii) antigens specific to the coccoid forms are expressed in vivo.

The present study was conducted to know the possible influence of the seed treatment, method of extraction and geographical origin on the quality and chemical composition of argan oil. Artisanally and semiautomatically extracted argan oils, from roasted and unroasted seeds, from interior and coast areas, were studied. The quality parameters analyzed were acid value, peroxide value, K 232 and K 270 , triacylglycerols and fatty acid composition, polar compounds, total phenols, tocopherol content and oil stability index (OSI). Seed treatment and extraction method showed a higher influence on quality parameters than geographical area; the quality parameters of the different oils were discussed. The total phenolic content in all analyzed samples was lower than 10 ppm. g-Tocopherol was the major tocopherol (84.4-86.4%) with a high contribution to the total tocopherol content (383-485 ppm). The OSI of the argan oil samples were well correlated (R = 0.97) with the tocopherol contents. The argan oil samples obtained from roasted seeds presented higher stability (26-38 h) than the oils from unroasted seeds (16-32 h).

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