Um patrimônio esmaecido: a produção açucareira, o Beco do Caminho Curto e a presença quilombola em Joinville (SC)

A presença da população negra escravizada e livre, e seus descendentes, é marcada por um forte silenciamento na historiografia oficial de Joinville (SC). A história da cidade muitas vezes é caracterizada por um discurso que privilegia a presença dos colonos europeus que se estabeleceram na região após a criação da Colônia Dona Francisca, em 1851. O artigo busca analisar a história dessas populações e o seu apagamento, considerando o contexto social, econômico e político que envolveu diversos atores. São discutidas novas abordagens sobre a história de Joinville que abarquem a escravidão, a produção açucareira e a posse da terra

Correlating the properties of near-room-temperature first- and second-order magnetocaloric materials

Several magnetocaloric materials have been proposed since the discovery of the Giant Magnetocaloric Effect. Although some have great potential as magnetocaloric refrigerants or working materials in thermomagnetic motors/generators, only a few have been tested experimentally or had their properties incorporated into validated mathematical models. While experiments are limited by material costs and specialized equipment to determine magnetic field-dependent properties such as specific heat capacity and magnetization, the development of correlation methods must ensure data quality and resolution over a wide range of conditions to reduce interpolations errors. Aiming to keep the number of baseline experimental data points at a minimum, we propose a fitting procedure to correlate thermomagnetic quantities (i.e., isofield specific heat capacity, magnetization and isothermal entropy change) that is accurate at intermediate (i.e., not directly measured) temperatures and applied magnetic fields. The method has been applied to different first-order materials (La(Fe,Mn,Si) H and MnFeP As ) and second-order materials (Gd and Gd Y ) with a good reproducibility of the isofield specific heat capacity, entropy–temperature diagram, adiabatic temperature change and magnetization behavior around room temperature at applied fields between 0 and 2 T

Development of Microalgae Biodiesel: Current Status and Perspectives

Microalgae are regarded as a promising source of biodiesel. In contrast with conventional crops currently used to produce commercial biodiesel, microalgae can be cultivated on non-arable land, besides having a higher growth rate and productivity. However, microalgal biodiesel is not yet regarded as economically competitive, compared to fossil fuels and crop-based biodiesel; therefore, it is not commercially produced. This review provides an overall perspective on technologies with the potential to increase efficiency and reduce the general costs of biodiesel production from microalgae. Opportunities and challenges for large-scale production are discussed. We present the current scenario of Brazilian research in the field and show a successful case in the research and development of microalgal biodiesel in open ponds by Petrobras. This publicly held Brazilian corporation has been investing in research in this sector for over a decade