300 eV. A rho value higher than 10(8) center dot cm was obtained when the doping concentration of Fe, [Fe], exceeded the major shallow donor (Si) concentration (5×10(17) cm(-3)). For those SI samples, the relative intensity of the yellow luminescence band at 2.2 eV, of
which the origin has been attributed to Ga vacancies (V-Ga) and/or defect complexes composed of V-Ga and O, over the UV/blue emission was remarkably decreased. Simultaneously, the Doppler broadening S parameter for the positron annihilation ASP2215 in vivo measurement, which represents the size or concentration of negatively charged vacancy type point defects such as V-Ga, was decreased. The results are consistent with the increase in formation energy of V-Ga due to the downward shift of the Fermi level by Fe doping. The values of rho, S, and W parameters that represents the fraction of positrons annihilated with core electrons, in the bulk region did not change remarkably while the positron diffusion length was increased by the annealing in N-2 between 600 and 1050 degrees C. Although the defect concentration in uncapped surface region was increased remarkably by annealing at 1050 degrees C due to the surface decomposition, the present results indicate that GaN:Fe can be used as a thermally stable SI GANT61 nmr substrate for electronic devices because the surface does not decompose during the epitaxial
growths of overlayers.”
“Phthalates have been used for decades in large quantities, leading to the ubiquitous exposure of the population. In an investigation of 63 German daycare centers, indoor air and dust samples were analyzed for
the presence of 10 phthalate diesters. Moreover, 10 primary and secondary phthalate metabolites were quantified in urine samples from 663 children attending these facilities. In addition, the urine specimens of 150 children were collected after the weekend and before they went to daycare centers.
Di-isobutyl phthalate (DiBP), dibutyl phthalate (DnBP), Natural Product Library and di-2-ethylhexyl phthalate (DEHP) were found in the indoor air, with median values of 468, 227, and 194 ng/m(3), respectively. In the dust, median values of 888 mg/kg for DEHP and 302 mg/kg for di-isononyl phthalate (DiNP) were observed. DnBP and DiBP were together responsible for 55% of the total phthalate concentration in the indoor air, whereas DEHP and DiNP were responsible for 70% and 24% of the total phthalate concentration in the dust.
Median concentrations in the urine specimens were 44.7 mu g/l for the DiBP monoester, 32.4 mu g/l for the DnBP monoester, and 16.5 mu g/l and 17.9 mu g/l for the two secondary DEHP metabolites. For some phthalates, we observed significant correlations between their concentrations in the indoor air and dust and their corresponding metabolites in the urine specimens using bivariate analyses.