RESUMO
Recently, scientists have shifted their focus from studying psychological resilience as a single, isolated construct (e.g. attribute or outcome) to studying it as a dynamic process encompassing a number of temporally related elements. Models depicting this process explain why some people adapt to stressor exposure, whereas others do not. To date, these process models did not sufficiently explain how people adapt differently to a stressor. To address this issue, we developed a new model of psychological resilience, called the Psychological Immunity-Psychological Elasticity (PI-PE) model. The aim of this article is to clarify this model and to discuss its added value. First, we explain how we derived the PI-PE model from the literature regarding both the crucial elements in any resilience process model and the (mal)adaptive outcomes following stressful events. Secondly, we describe the different elements that make up the model. Characteristic of the PI-PE model is that it distinguishes between two pathways of psychological resilience - psychological immunity and psychological elasticity - with four adaptive outcomes, namely sustainability, recovery, transformation and thriving. To explain how people arrive at these different outcomes, we argue that two consecutive mechanisms are critical in these pathways: tolerance and narrative construction. Taken as a whole, the PI-PE model presents a comprehensive framework to inspire both research and practice. It explains how the process of psychological resilience works differently for different people and how to support individuals in their process towards successfully and differently adapting to stressors.
RESUMO
BACKGROUND: In times of global warming there is an urgent need to replace fossil fuel-based energy vectors by less carbon dioxide (CO2)-emitting alternatives. One attractive option is the use of molecular hydrogen (H2) since its combustion emits water (H2O) and not CO2. Therefore, H2 is regarded as a non-polluting fuel. The ways to produce H2 can be diverse, but steam reformation of conventional fossil fuel sources is still the main producer of H2 gas up to date. Biohydrogen production via microbes could be an alternative, environmentally friendly and renewable way of future H2 production, especially when the flexible and inexpensive C1 compound formate is used as substrate. RESULTS: In this study, the versatile compound formate was used as substrate to drive H2 production by whole cells of the thermophilic acetogenic bacterium Thermoanaerobacter kivui which harbors a highly active hydrogen-dependent CO2 reductase (HDCR) to oxidize formate to H2 and CO2 and vice versa. Under optimized reaction conditions, T. kivui cells demonstrated the highest H2 production rates (qH2 = 685 mmol g-1 h-1) which were so far reported in the literature for wild-type organisms. Additionally, high yields (Y(H2/formate)) of 0.86 mol mol-1 and a hydrogen evolution rate (HER) of 999 mmol L-1 h-1 were observed. Finally, stirred-tank bioreactor experiments demonstrated the upscaling feasibility of the applied whole cell system and indicated the importance of pH control for the reaction of formate-driven H2 production. CONCLUSIONS: The thermophilic acetogenic bacterium T. kivui is an efficient biocatalyst for the oxidation of formate to H2 (and CO2). The existing genetic tool box of acetogenic bacteria bears further potential to optimize biohydrogen production in future and to contribute to a future sustainable formate/H2 bio-economy.