Abstract Understanding the dynamics of microbial plankton communities, their metabolic processes and taxonomic composition in oligotrophic ocean basins has been one of the central tasks of contemporary marine microbial ecology and one of the main challenges in a changing global ocean. However, despite its ecological importance, the South Atlantic Subtropical Gyre (SASG) remains poorly understood in relation to marine microbes, which comprise the major drivers of biogeochemical cycles and the largest carbon sink to the deep ocean. This review presents the state of the art of microbial ecology in the SASG, including the adjacent oligotrophic region, the Southwest Atlantic Ocean (SWAO). We have also addressed the theoretical and methodological trends in this field since 1970s, focusing on the main milestones that led to the more-detailed current knowledge of the role of oligotrophic gyres in the global carbon cycle. Finally, we discussed the general patterns of microbial community composition in the SASG, focusing on their potential responses to environmental factors. In spite of increasing efforts to investigate this region, SASG is among the least known oceanic provinces, which has hampered the debate over whether the oligotrophic ocean acts as a sink or source of CO2 into the atmosphere.

The aim of this work was to correlate parameters of the metallurgical structure such as size and reorganizing the grains, as well as the hardening capacity and the samples distortion of AISI 1045 steel plastically deformed by roll and then fractioned, with average values root means square RMS of a Barkhausen Emission. The analyzed samples were deformed by using forces of 500, 1500 and 2500 N, angular speed of 27, 54, and 110 r.p.m and tool advance of 0,075; 0,125 and 0,25 mm / rev. Then, they underwent a traction process using a CRITM DNS 200 machine, with a load of 200 kN. It was observed that the EMB signal presented an increasing performance in correspondence with the deformation decline and the increasing in tension and the hardness degree. The study of commercial steel AISI 1045 plastically deformed with roller and then pulled with EMB technique, allowed corroborating the potential of this technique as a non-destructive testing.

El trabajo tuvo como objetivo correlacionar parámetros de la estructura metalúrgica, tales como tamaño y reorganización de los granos, así como la capacidad de endurecimiento y la deformación de muestras de acero AISI 1045 deformado plásticamente por rodillo y luego traccionado, con los valores de la raíz media cuadrática RMS de una Emisión Magnética de Barkhausen (EMB). Las muestras analizadas se deformaron utilizando fuerzas de 500 N, 1500 N y 2500 N; velocidad angular de 27 rev/min, 54 rev/min y 110 rev/min y avance de la herramienta de 0,075 mm/rev; 0,125 mm/rev y 0,25 mm/rev. Luego se sometieron a un proceso de tracción empleando una máquina CRITM DNS 200, con carga de 200 kN. Se observó que la señal de EMB presentó, de forma general, un comportamiento creciente en correspondencia con la diminución de la deformación, el aumento de la tensión y el grado de dureza. El estudio del acero comercial AISI 1045, deformado plásticamente con rodillo y luego traccionado con la técnica EMB, permite corroborar la potencialidad de esta técnica como ensayo no destructivo.