The article presents the reviewed and summarised research activities of the Polish research groups on gravimetry and gravity field modelling in the period of 2019–2022. It contains the results of absolute gravity surveys for the maintenance of the international gravity reference level in Poland and Europe, and for geodynamic research with an emphasis on metrological aspects. It also contains relative gravimetry issues as well as the results of marine gravity surveys in the southern Baltic Sea. Non-tidal gravity changes were extensively investigated. Long-term gravity variations were monitored at the Borowa Gora Geodetic-Geophysical Observatory and in a few other locations in Poland. The contribution of gravimetric records to seismic studies was investigated. Temporal variations of the gravity field from GRACE (Gravity Recovery and Climate Experiment) and GRACE-FO (GRACE Follow-On) data, in particular, deformations of the Earth’s surface as well as temporal variations of heights, total water storage and groundwater storage were investigated. Moreover, GRACE-based products and the performance of monthly Global Geopotential Models (GGMs) were a subject of research. GGMs developed in last years were evaluated. The research on developing new approaches in geoid modelling and their validation was conducted. New regional and local geoid models were determined for Poland and Ethiopia. The use of different techniques for estimating the absolute sea level at sites of the selected network in the Baltic Sea was investigated.

The work motivation was to investigate in vitro system simulating drug release from Drug Eluting Stent (DES). The experiments were conducted in a custom designed unit simulating drug release from polymer covering DES in a simplified way. The active substance diffuses from a thin, internal annular layer of hydrogel (imitating “stent”) to the outer cylindrical layer of hydrogel (“artery wall”) and is at once drifted away by coaxially flowing solution (“blood”). The conducted research proved functionality of the experimental unit. The rate of mass transfer depends considerably on the mass driving force and on the affinity of substance-hydrogel. The volumetric flow rate and liquid viscosity did not affect the process significantly. The effective diffusion coefficient was calculated as a process parameter and then used in the other variants. Diffusion in hydrogel is the mechanism limiting the mass transfer in the examined system. For the first attempt, the diffusive model used in literature was employed. The provided calculations are consistent with experimental data and therefore show that despite its simplifications the model allows to estimate the amount of released substance.
In conclusion, the relative substance mass, changing over time, was estimated in the respective parts of the unit. The prospect of determining the relative mass of the substance appearing in the subsequent parts of the system over time provides the opportunity to adjust the respective process parameters, which will facilitate control over the rate of mass release.