Early in its history, Earth's surface developed from an uninhabitable magma ocean to a place where life could emerge. The first organisms, lacking ion transporters, fixed the composition of their cradle environment in their intracellular fluid. Later, though life adapted and spread, it preserved some qualities of its initial environment within. Modern prokaryotes could thus provide insights into the conditions of early Earth and the requirements for the emergence of life. In this work, we constrain Earth's life-forming environment through detailed analysis of prokaryotic intracellular fluid. Rigorous assessment of the constraints placed on the early Earth environment by intracellular liquid will provide insight into the conditions of abiogenesis, with implications not only for our understanding of early Earth but also the formation of life elsewhere in the Universe.
O impacto gerado pelos resíduos da indústria siderúrgica provoca discussões acerca das melhores formas de destinação final dos subprodutos resultantes do processo de geração de ligas metálicas. Visando mitigar esses problemas, este trabalho apresenta os resultados dos estudos sobre a caracterização da escória de ferro silício-manganês para potencial aplicação em projetos de misturas com solo, na construção de camadas de base e sub-base de pavimento rodoviário. A relevância deste trabalho se mostra diante da necessidade de prover uma destinação ambientalmente adequada para subprodutos de processos siderúrgicos que podem prover a sociedade de soluções viáveis, ou seja, se tornar um coproduto que reduza o consumo de matéria-prima natural, além de promover economia financeira. Alguns métodos utilizados são tradicionais, como Granulometria, Densidade e absorção, e Abrasão Los Angeles. Outros são usados mais recentemente para caracterizar agregados, como Microscópio Eletrônico de varredura (MEV) e Sistema de caracterização de agregados por imagem (AIMS). Complementarmente, são apresentados os dados obtidos na Degradação após o teste de compactação Proctor e a determinação da perda ao choque no equipamento Treton. Os resultados encontrados nos ensaios mencionados se mostram satisfatórios diante dos valores estabelecidos nas normas específicas para cada metodologia. Finalmente, conclui-se que a escória de ferro de silício-manganês apresenta propriedades geotécnicas compatíveis com as estabelecidas para uso em base e sub-base de pavimentos flexíveis.
Based on mitigation strategies for the rational use of resources and conscious consumption of inputs, it is important to develop tools that allow the measurement of environmental impacts and greenhouse gas emissions, for better decision-making in the planning of railway infrastructure activities. Therefore, this article presents a method for evaluating railway infrastructure projects, having as a parameter the potential impact of global warming when different materials are used in the sub-ballast, to improve the support capacity of the railway pavement. As a technical criterion for evaluation, the mechanical behavior of the subgrade was considered in a condition of moisture above the optimal level, with a sub-ballast composed of sandy material as a baseline for comparison. The results, considering the environmental impact, clearly indicated that the use of a soil-cement mixture in the sub-ballast was the best option. Furthermore, even in the face of more frequent renovation of the permanent way, the reference scenario was more attractive than those with use of a combination of soil-emulsion and hot mix asphalt.
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