Joao Carvalheiro

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This paper describes a Stand-Alone Energy System Supported by Totally Renewable Hydrogen Production. The system was conceived for off-grid operation and is composed by solar panels, a wind turbine, a fuel-cell, an electrolyzer, hydrogen tanks and power electronics converters. The basic control strategy for the overall system considers the pressurized(More)
Although Malacostracan species represent an important alimentary human resource, the ultrastructure of oogenesis in P. kerathurus remains unknown. Previtellogenic oocytes of Penaeus kerathurus possess a large nucleus with several peripheral nucleoli. The endoplasmic reticulum (ER) is originated from expansions of the nuclear envelope (NE) and contains small(More)
Besides the components of typical nucleoli, three other nuclear structures were identified in spermatogonia by positive silver staining: dense centers, fibrillar regions, and dense granules. There was a close relationship between the dense centers and fibrillar regions in spermatogonia and spermatocytes, whereas the dense granules, which appeared dispersed(More)
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