APPLICATION OF GRAPHENE OXIDE IN CEMENTITIOUS COMPOSITES FOR CEMENT CONTENT REDUCTION

oai:ojs.journaluts.emnuvens.com.br:article/6Cement production is responsible for 5% of CO2 emissions worldwide. The concern about the pollution derived from the construction industry has brought attention to the need of developing more sustainable construction materials and processes. Admixtures based on nanometric graphene oxide have the potential to enhance mechanical properties and durability of cementitious composites. In this context, an experimental program was conducted to evaluate how the addition of graphene oxide may be used to reduce cement content in concretes, maintaining the same mechanical properties of conventional concretes (control matrices, with no graphene oxide additions). Kinetics of hydration of cement pastes was evaluated by isothermal calorimetry, phase evolution during hydration was determined by X-ray diffraction coupled with quantitative Rietveld analysis and mechanical properties were evaluated by compressive strength. Results indicate that graphene oxide additions provide a faster hydration rate until 24 h and generate a larger amount of C-S-H gel, increasing mechanical strength of the matrix. By the addition of graphene oxide dispersion (0.4% of solid content) at 0.02% by cement weight, cement content reductions of up to 15% may be achieved, maintaining the same compressive strength as the control matrices. From this research, a reduction in cement content to obtain more sustainable construction materials and processes may be achieved

Feminist Reflections on the Scope of Labour Law: Domestic Work, Social Reproduction and Jurisdiction

Drawing on feminist labour law and political economy literature, I argue that it is crucial to interrogate the personal and territorial scope of labour. After discussing the “commodification” of care, global care chains, and body work, I claim that the territorial scope of labour law must be expanded beyond that nation state to include transnational processes. I use the idea of social reproduction both to illustrate and to examine some of the recurring regulatory dilemmas that plague labour markets. I argue that unpaid care and domestic work performed in the household, typically by women, troubles the personal scope of labour law. I use the example of this specific type of personal service relation to illustrate my claim that the jurisdiction of labour law is historical and contingent, rather than conceptual and universal. I conclude by identifying some of the implications of redrawing the territorial and personal scope of labour law in light of feminist understandings of social reproduction

Genomic history of coastal societies from eastern South America

Sambaqui (shellmound) societies are among the most intriguing archaeological phenomena in pre-colonial South America, extending from approximately 8,000 to 1,000 years before present (yr bp) across 3,000 km on the Atlantic coast. However, little is known about their connection to early Holocene hunter-gatherers, how this may have contributed to different historical pathways and the processes through which late Holocene ceramists came to rule the coast shortly before European contact. To contribute to our understanding of the population history of indigenous societies on the eastern coast of South America, we produced genome-wide data from 34 ancient individuals as early as 10,000 yr bp from four different regions in Brazil. Early Holocene hunter-gatherers were found to lack shared genetic drift among themselves and with later populations from eastern South America, suggesting that they derived from a common radiation and did not contribute substantially to later coastal groups. Our analyses show genetic heterogeneity among contemporaneous Sambaqui groups from the southeastern and southern Brazilian coast, contrary to the similarity expressed in the archaeological record. The complex history of intercultural contact between inland horticulturists and coastal populations becomes genetically evident during the final horizon of Sambaqui societies, from around 2,200 yr bp, corroborating evidence of cultural change

Présentation du texte de Jules Vuillemin « De la connaissance sensible et de la parité qu’elle manifeste entre l’homme et l’animal »

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