Análise e caracterização do casco de um navio naufragado na Baia de Todos os Santos - Bahia – Brasil / Analysis and characterization of the hull of a shipwrecked ship in the Baia de Todos os Santos - Bahia - Brazil

Esse estudo apresenta a análise e caracterização do material metálico que compõe o casco de um navio naufragado no ano de 1905 na Baía de Todos os Santos da cidade de Salvador – Bahia. As amostras foram coletadas de fragmentos do casco do naufrágio por mergulho autônomo. Os resultados obtidos por meio de técnicas como a espectrometria de emissão ótica, microdureza e microscopia ótica permitiram a comparação qualitativa e quantitativa da composição química e aspecto da estrutura metalúrgica, como também do processo de fabricação para obtenção desse material estrutural no século passado e nos dias atuais. A difração de raios X da concreção mostrou que a mesma é constituída por quartzo, carbonato de cálcio, carbonato de magnésio e pequenas quantidades de hematita. A constituição do casco do Black Adder construído em 1869 consiste em uma liga de aço baixo Carbono, contendo elevados teores de impurezas, principalmente Fósforo e Enxofre, demonstrando a baixa qualidade metalúrgica da época. Palavras-chave:

Community-acquired pneumonia by Legionella pneumophila serogroups 1–6 in Brazil

SummaryA prospective cohort study of adult patients hospitalized due to community-acquired pneumonia was carried out for 1 year in a Brazilian university general hospital to detect the incidence of community-acquired pneumonia by Legionella pneumophila serogroups 1–6. During a whole year, a total of 645 consecutive patients who were hospitalized due to a initial presumptive diagnosis of respiratory disease by ICD-10 (J00–J99), excluding upper respiratory diseases, were screened to detect the patients with community-acquired pneumonia. Fifty-nine consecutive patients hospitalized due to community-acquired pneumonia between July 19, 2000 and July 18, 2001, were included in the study. They had determinations of serum antibodies to L. pneumophila serogroups 1–6 by indirect immunofluorescence antibody test at the Infectious Diseases Laboratory of University of Louisville (KY, USA) and urinary antigen tests for L. pneumophila serogroup 1. Three patients had community-acquired pneumonia by L. pneumophila serogroups 1–6, two patients being diagnosed by seroconversion and positive urinary antigen tests; the other had negative serologies but strongly positive urinary antigen test. The incidence of community-acquired pneumonia by L. pneumophila serogroups 1–6 in our hospital was 5.1%

Dentin deproteinization effect on bond strength of self-adhesive resin cements

This study examined the effect of deproteinization on the bond strength between self-adhesive resin cements and dentin surfaces that were untreated (control), acid-etched, or acid-etched and subjected to a post-etch deproteinization treatment. Cylinders of RelyX Unicem or BisCem (n = 6) cement were build-up on the dentin surfaces and tested to determine shear strength. The results were analyzed using two-way ANOVA and Tukey's test (5%). While neither dentin pretreatment improved the bond strength for RelyX Unicem, deproteinization treatments resulted in greater bond strength in BisCem specimens while acid etching alone did not improve the performance of the material

Influence of Pre-Milling of Cr₃C₂-25 NiCr Spray Powder on the Fatigue Life of HVOF-Sprayed Coating on ASTM A516 Steel Substrate

The aim of the present investigation is to evaluate the influence of the powder size of Cr3C2-25NiCr spraying powder on the fatigue behavior of HVOF-sprayed coating on the ASTM A516 steel substrate. Conventional commercial Cr3C2-25NiCr spraying powder was previously treated through high-energy milling. The crystallite sizes of milled powders were measured by X-ray diffraction and transmission electronic microscopy. Three different powder formats of the same Cr3C2-25NiCr composite were subjected to HVOF spraying to produce (i) a Milled-Coating (from high-energy milled spray powder), (ii) an Original-Coating (from conventional commercial spray powder), and (iii) a 50%–50% mixture of both (Milled + Original-Coating). The same spraying conditions were adopted for all the assessed cases. The sprayed coatings were investigated through the Knoop hardness test and SEM-EDS analysis. In addition, 3-point bending fatigue tests were conducted at different stress levels up to 107 cycles. The coating morphology and roughness effects on fatigue behavior were analyzed. The Cr3C2-25NiCr milled coating presented a lower fatigue life above the fatigue limit and a higher fatigue limit than other coatings; this outcome could be attributed to its lower surface roughness and finer grain size microstructure