Mechanical and microstructural properties of redispersible polymer-gypsum composites

Studies on gypsum modified by polymers have been conducted to assess the potential of improvement in the mechanical performance, water resistance and increasing the setting time, facilitating its handling. Gypsum-based compounds made with different additions of redispersible polymers were studied, such as: ethylene-vinyl acetate (EVA), vinyl acetate terpolymer, vinyl laurate and vinyl chloride (VA/VL/VC), and vinyl acetate and vinyl versatate (VA/VeoVA). The influence on setting time, microstructural formation and on the bending performance was assessed, as well as and compression of the hardened gypsum. The composites were prepared using a polymer concentration of 5% and 10%, and water/gypsum ratio of 0.6. The addition of the polymer decreased the structural robustness and change in the microstructure. We concluded that the reduction in the amount of water through additives may allow a more complete and robust training of gypsum crystals and compounds with better mechanical performance223COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESnão te

Model-based estimation of transmissibility and reinfection of SARS-CoV-2 P.1 variant

Acknowledgements We are grateful for the collaborative work of the reviewers and the entire group of the Observatório COVID-19 BR. In particular, we thank Verônica Coelho for critical inputs. We also thank the research funding agencies: the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brazil (Finance Code 001 to F.M.D.M., L.S.F. and T.P.P.), Conselho Nacional de Desenvolvimento Científico e Tecnológico—Brazil (grant number: 315854/2020-0 to M.E.B., 141698/2018-7 to R.L.P.S., 313055/2020-3 to P.I.P., 312559/2020-8 to M.A.S.M.V., 311832/2017-2 to R.A.K., 305703/2019-6 to A.A.M.S.) and Fundação de Amparo à Pesquisa do Estado de São Paulo—Brazil (grant number: 2019/26310-2 and 2017/26770-8 to C.F., 2018/26512-1 to O.C., 2018/24037-4 to S.P. and contract number: 2016/01343-7 to R.A.K.). The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the Centers of Disease Control and Prevention.Peer reviewe