RESUMEN
In this work, the liquid-liquid interfacial properties of methanol plus n-alkane (n-hexane, n-heptane, n-octane) mixtures are investigated at atmospheric pressure by two complementary molecular modelling techniques; namely, molecular dynamic simulations (MD) and density gradient theory (DGT) coupled with the PC-SAFT (perturbed-chain statistical associating fluid theory) equation of state. Furthermore, two molecular models of methanol are used, which are based on a non-polarisable three site approach. On the one hand, is the original (flexible) TraPPE-UA model force field. On the other hand, is the rigid approximation denoted as OPLS/2016. In both cases, n-alkanes are modelled using the TraPPE-UA model. Simulations are performed using the direct coexistence technique in the ensemble. Special attention is paid to the comparison between the estimations obtained from different methanol models, the available experimental data and theoretical calculations. In all cases, the rigid model is capable of predicting the experimental phase equilibrium and interfacial properties accurately. Unsurprisingly, the methanol-rich density and interfacial tension are overestimated using the TraPPE model combined with Lorentz-Berthelot mixing rules for predicting the mixture behaviour. Accurate comparison between MD and DGT plus PC-SAFT requires consideration of the cross-interactions between individual influence parameters and fitting the ßij values. This latter aspect is particularly important because it allows the exploitation of the link between the EOS model and the direct molecular simulation of the corresponding fluid. At the same time, it was demonstrated that the key property defining the interfacial tension value is the absolute concentration of methanol in the methanol-rich phase. This behaviour indicates that there are more hydrogens bonded with each other, and they interact favourably with an increasing number of carbon atoms in the alkane.
RESUMEN
Neste artigo busca-se inventariar o estado atual das inter-relações entre mudanças ambientais globais e saúde, incluindo uma revisão do estado atual das ameaças de origem antrópica sobre a biodiversidade, trazendo o enfoque ecossitêmico como linha de pesquisa para a melhoria da qualidade de vida. Os processos de mudanças ambientais globais afetam a saúde humana, direta ou indiretamente, pontual ou regionalmente. Alterações na química da atmosfera, mudanças climáticas, degradação do solo, perda da biodiversidade, urbanização e grandes empreendimentos, escassez de água e poluições químicas de âmbito global podem ter consequências severas para o bem-estar humano, saúde e sobrevivência. A importância dessas mudanças para a saúde humana dependerá de quanto as populações são ou podem ser afetadas no futuro, do grau e amplitude dos impactos e das adaptações biológicas e das formas de mitigação e controle disponíveis. Vários programas têm sido desenvolvidos em todo o mundo, mas é preciso avançar em modelos conceituais, incluir as questões das mudanças ambientais globais na agenda científica e institucional brasileira, buscar modelos de desenvolvimento sustentável, criar mecanismos que interropam a perda da biodiversidade, minimizar o uso de poluentes e sensibilizar as pessoas para o possível esgotamento dos recursos naturais renováveis
In this article we intended to survey the current state of relationships between global environmental changes and health. It includes a revision of the current state of threats of anthropic origin on biodiversity, bringing an ecosystem approach as a field of research for the improvement of quality of life. Global environmental changes affect human health directly or indirectly, locally or regionally. Alterations in the chemistry of the atmosphere, climate changes, soil degradation, loss of biodiversity, urbanization and major development sites, shortage of water and chemical pollutants constitute driving forces that can have severe consequences for human well-being and health as well as, its survival. The importance of these changes for human health will depend on how populations may be affected in the future, the severity and magnitude of the impact, the possibility of biological adaptations, and the availability of strategies to mitigate and control. Several programs have been developed around the world. However, the Brazilian scientific and institutional agenda needs to move forward in conceptual models that include aspects related to global environmental changes, searching for models of sustainable development, and creating mechanisms that interrupt the loss of biodiversity, minimize the use of pollutants, establish awareness programs concerning the exhaustion of renewable natural resources.