The diffusion of boron implanted in preamorphized silicon and rapid thermal annealed with an electron beam is analyzed. For an implanted dose of 5× 1015 B+/cm2 an enhanced diffusion in the early phase of the annealing is clearly observed. The enhancementof the diffusivity is of about a factor 30 at t 0 and exponentially decreases with a constant time of 0.5 s at the temperature of 1100 °C. For lower implanted dose (1 × 1015 B+/cm2) the phenomenon is less remarkable and no conclusive evidence on the existence of enhanced diffusion can be drawn. It is also observed that a recrystallization preannealing step at 550 °C for 1 h does notavoid enhanced diffusion during the rapid thermal annealing. The mechanismswhich could give rise to these effects are reported and discussed.
This work is to present results of flash evaporation of PbTe directly over single crystals p-type Si substrates, in order to produce heterojunction infrared detectors (HIRD), working at 4.3.tm IR wavelength. The evaporation was performed on modified JEOL vacuum equipment, model JEE4B(a), working with vacuum pressure around 10-5 torr, using diffusion pump. The HIRDs produced with this method presented the same detectivity (D*) values of HIRDs made with Hot Wall Epitaxial System (HWE)(b), in which PbTe epitaxial layers were grown directly over the same Si substrates, where an ionic pump reached about 10-torr as vacuum pressure. The best results, were obtained with PbTe layers grown with Molecular Beam Epitaxial (MBE) method(c) directly over Si substrates, where the vacuum pressure is around 10-9 torr, also using an ionic pump. The advantage of growing PbTe directly over Si wafers is that the HIRDs perform at room temperature.
Bioindicator species are used to assess the damage and magnitude of possible impacts of anthropic origin on the environment, such as the reckless consumption of antimicrobials. Chelonia mydas has several characteristics that make it a suitable bioindicator of marine pollution and of the presence of pathogens that cause diseases in humans. This study aimed to investigate the green sea turtle as a reservoir of resistant bacteria, mainly because C. mydas is the most frequent sea turtle species in Brazilian coastal regions and, consequently, under the intense impact of anthropic factors. Free-living green sea turtles ranging from 42.8 to 92 cm (average = 60.7 cm) were captured from Itaipú Beach, Brazil. Cloaca samples (characterizing the gastrointestinal tract) and neck samples (representing the transient microbiota) were collected. Bacterial species were identified, and their was resistance associated with the antimicrobials cephalothin, ciprofloxacin, gentamicin, tetracycline, and vancomycin. Citrobacter braaki, Klebsiella oxytoca, K. variicola and Proteus mirabilis were found resistant to cephalothin and Morganella morganii and Enterococcus faecalis tetracycline-resistant isolates in cloaca samples. In neck samples, species resistant to tetracycline were Salmonella sp., Serratia marcescens, S. ureylitica and Proteus mirabilis. This data reinforces that the green turtle is a bioindicator of antimicrobial resistance (AMR).
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