Emeraldine base as corrosion protective layer on aluminium alloy AA5182, effect of the surface microstructure

International audienceAA5182 aluminium alloy cold rolled samples were coated by thin films of emeraldine base (EB) obtained from a 5% solution in N-methylpyrrolidinone. Accelerated corrosion tests prove this coating very effective for corrosion protection of aluminium alloys in neutral environment. This study underlines the prominent role of surface cathodic intermetallic particles in pit initiation and coating break down in enhanced corrosion conditions and suggest that, beside the EB barrier properties, the enhanced corrosion resistance observed on the EB coated samples could partly arise from two other mains factors:• a weak redox activity of the polymer which passivate the metal,• a proton involving self-healing process taking place at the polymer–metal interface, which contributes to delay local acidification in first steps of corrosion on EB coated aluminium surfaces

Soroprevalência da infecção por Helicobacter pylori em crianças de diferentes níveis sócio-econômicos em Porto Velho, Estado de Rondônia Seroprevalence of Helicobacter pylori infection among children of different socioeconomic levels in Porto Velho, State of Rondônia

O estudo investigou a soroprevalência de infecção pelo Helicobacter pylori em 200 (subdivididas em 2 grupos) crianças da Cidade de Porto Velho, Rondônia. A prevalência da soropositividade variou consideravelmente de acordo com o nível sócio-econômico, onde 51% das crianças de baixo nível e 24% de classe média eram positivas. As características da população infantil relacionadas ao sexo, raça e dieta alimentar não representaram fatores de risco para a aquisição da infecção; porém, a maioria das infectadas pertencia à faixa etária de cinco ou mais anos, independente do nível sócio-econômico. A distribuição fenotípica dos grupos sanguíneos ABO, entre os indivíduos infectados e não infectados, mostrou4 que a sororeatividade ao Helicobacter pylori foi maior entre as crianças do grupo sanguíneo O, sugerindo que há uma maior susceptibilidade genética destas crianças para a infecção pelo Helicobacter pylori.<br>This study investigated the seroprevalence of Helicobacter pylori infection in 200 children in the city of Porto Velho, State of Rondônia, divided in two groups of 100 children. The prevalence of seropositivity varied considerably according to socioeconomic level, such that 51% of the lower-level children and 24% of the middle-class children were positive. The characteristics of the child population relating to sex, ethnicity and diet did not represent risk factors for acquiring the infection. However, most of the infected children were in the age group of five years or older, independent of socioeconomic level. The phenotypic distribution of ABO blood groups among the infected and uninfected individuals showed that the seroreactivity to Helicobacter pylori was greater among the children with the O blood type, thus suggesting that these children have greater genetic susceptibility to infection by Helicobacter pylori