Overgrowth region

Suppression of the defect-related emissions and enhancement of the NBE exciton emission has been found in layers produced by different ELO techniques. Such layers have an improved structural quahty owing to reduced density of the TDs and BSE in the overgrowth regions if the ELO stripes are with optimal orientation, that is the orientation perpendicular to the c axis or to its projection. In addition, the ELO layers possess a smooth surface morphology and can serve as templates for subsequent growth of device structures. 

Faiz et al. (1996) have applied micro-PIXE analysis to study solute distributions in a single crystal sample of YiBa2Cu307 5 high temperature superconductor (YBCO) of dimensions 1.3 mm x 1.5 mm x 75 pm. It contained a small secondary crystal overgrowth of dimensions 340 x 340 x 100 pm3. The interface region between the smaller crystal and the base crystal was covered with a material which appeared to be residual flux. The instrument employed a 2.5 MeV focused proton beam of about 4 pm resolution, which could scan an area of 500 x 500 pm2 on the sample surface. The microbeam current was kept low (typically about 30 pA) to avoid any damage to the sample. 

Vitamin B12 deficiency also occurs when the region of the distal ileum that absorbs the vitamin B12-intrinsic factor complex is damaged, as when the ileum is involved with inflammatory bowel disease, or when the ileum is surgically resected. In these situations, radioactively labeled vitamin B12 is not absorbed in the Schilling test, even when intrinsic factor is added. Other rare causes of vitamin B,2 deficiency include bacterial overgrowth of the small bowel, chronic pancreatitis, and thyroid disease. Rare cases of vitamin B12 deficiency in children have been found to be secondary to congenital deficiency of intrinsic factor and congenital selective vitamin Bi2 malabsorption due to defects of the receptor sites in the distal ileum. 

Figures 3 and 13 show two spinel-pyroxene-rich CAIs from Mighei (CM) that are typical of the kinds of seen in many chondrite types, including CO, CR, ordinary, and enstatite chondrites. Besides being much smaller than their CV3 kindred, these CM examples typically are deficient in melilite and anorthite. Figure 3 shows what MacPherson et al. (1983) called a nodular spinel-pyroxene inclusion, in which the central spinel region consists of numerous spinel crystals in a dense overgrowth. In contrast, the CAl in Figure 13 is a chain-like inclusion (MacPherson and Davis, 1994) that consists of numerous small linear chains of spinel and even some individual spinel crystals. Each has its own individual pyroxene rim. Although clearly the ensemble is part of a single object, its individual components are separated from one another by up to 50 p,m of intervening meteorite matrix.

The possible model for brain growth for people with autism spectrum disorder consists of a period of overgrowth before the age of 5 years, in which several regions of the brain (and overall brain size) are enlarged. From 5 years onwards, this period of growth stops. In some autistic individuals this may be followed by a period of degeneration - a decrease in neuron numbers and volume reduction in some areas of the brain (Courchesne et al, 2007), as reported in various post-mortem studies. 

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