RESUMO
The Covid 19 pandemic has caused dramatic disruptions in the public transport sector that has seen a stark downturn in many cities across the globe, calling into question previous efforts to reduce air pollution and CO2 emissions by expanding this sector. Especially, the current surge of individual car use is worrying and the question remains which users might be able and willing to substitute public transport by cycling. This effect is interesting to study for the case of Hanover Region, because of the well-developed biking infrastructure that makes biking a viable alternative to individual car use. In this paper, we analyze survey data from June 2020 on the use of transportation modes before and during the pandemic in the Hanover Region. We ask if and how the over 4.000 participants substitute public transport and what characterizes those who chose biking over individual car use. We use multivariate regression models and find evidence that Stadtbahn (local light rail) and bus are substituted by bike, car and working from home, while train use is not significantly replaced by car and seems to be positively related to bike use. The data also shows that women have a higher level of fear of infection than men have during public transport use and therefore reduce public transport use more. Moreover, income displays a positive effect on increased car use while cycling is independent of socio-economic indicators but instead driven by the eco-consciousness of users. Surprisingly, we find that car use was increased in particular by residents of Hanover city, while it was decreased by residents of less densely populated urban areas in the region.
RESUMO
Biphasic dissolution models were proposed to provide good predictive power for in vivo absorption kinetics. However, up to date the impact of hydrodynamics in mini-scale models are not well understood. Consequently, the aim of this work was to investigate different setups of a previously published mini-scale biphasic dissolution model (miBIdi-pH-II) to better understand the relevance of hydrodynamics for evaluating kinetic parameters and to simultaneously increase the robustness of the experimental model. As a first step, the hydrodynamics within the aqueous phase were characterized by in silico simulations of the flow patterns. Different settings, such as higher rotation speeds of the paddles, the implementation of a second propeller into the aqueous phase, and different shapes of aqueous stirrers were investigated. Second, to evaluate the results of the in silico simulations, in vitro experiments with glitter were carried out. Last, the same settings were applied in the miBIdi-pH-II using dipyridamole (DPD) as model compound to estimate kinetic parameters by applying a compartment-based modelling approach. Both in vitro experiments with glitter or DPD demonstrated the adequateness of the previous in silico hydrodynamic simulations. The use of higher rotation speeds and a second aqueous propeller resulted in more homogeneous mixing of the aqueous phase. This resulted in faster distribution of dissolved active pharmaceutical ingredient (API) into the octanol phase. A kinetic model was successfully applied to quantify the influence of hydrodynamics on the partitioning rate of the API into the octanol phase. In conclusion, the combination of in silico and in vitro methods was demonstrated to be powerful for investigating the flow patterns within the miBIdi-pH-II. A comprehensive understanding of the hydrodynamics and the respective influence on the dissolution and apparent partitioning into the octanol phase in the biphasic dissolution model was obtained and completed by using a compartmental kinetic model. This model allowed successful quantification of how the hydrodynamics influence the partitioning of API into the octanol phase.
