Difteria pelo Corynebacterium ulcerans: uma zoonose emergente no Brasil e no mundo

O artigo revisa a literatura sobre a emergência de infecções humanas causadas por Corynebacterium ulcerans em diversos países, incluindo o Brasil. Foi realizada análise de artigos publicados entre 1926 e 2011 nas bases Medline/PubMed e SciELO, bem como artigos e informes do Ministério da Saúde. Apresenta-se um esquema de triagem, rápido, econômico e de fácil execução, capaz de permitir a realização do diagnóstico presuntivo de C. ulcerans e C. diphtheriae na maioria dos laboratórios brasileiros públicos e privados. A circulação de C. ulcerans em vários países, aliada aos recentes casos de isolamento do patógeno no Rio de Janeiro, é um alerta a clínicos, veterinários e microbiologistas sobre a ocorrência de difteria zoonótica e a circulação do C. ulcerans em regiões urbanas e rurais do território nacional e/ou da América Latina

Properties of Carbon Aerogels and Their Organic Precursors

International audienceAerogels are sol-gel derived porous solids with structural properties, such as porosity, pore size, pore and solid phase connectivity that can be tailored over a wide range to provide unique material properties for different fields of applications, such as filters and adsorbers, catalyst supports, electrodes for electrical energy storage, and materials for lightweight construction or thermal insulation.In this context, carbon aerogels and their organic precursor represent an important class of aerogels with very different physical properties at similar structural characteristics. This is due to the different intrinsic properties of the respective backbone components: At given meso- and macrostructure carbon aerogels are characterized by high thermal and electrical conductivity, significant mechanical brittleness, high porosity of the backbone phase related to micropores (<2 nm), and thus specific surface areas up to about 2000 m2/g. In contrast, the respective organic precursors exhibit very small electrical conductivities and a significantly reduced heat transfer via the aerogel backbone phase; they furthermore may be mechanically more flexible and are limited to specific surface areas below 1000 m2/g. The chapter provides an overview over typical structural and physical properties of carbon aerogels and their precursors.Understanding structure–property relationships and optimizing aerogels for different applications requires reliable characterization techniques. The review article addresses different characterization techniques as well as the problem of artifacts upon structural characterization; the latter is due to the unique combination of small pore sizes and large porosities characteristic for aerogels. With that in mind, the article alternative, in part even more powerful approaches