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We report on an improved test of the Universality of Free Fall using a rubidium-potassium dual-species matter wave interferometer. We describe our apparatus and detail challenges and solutions relevant when operating a potassium interferometer, as well as systematic effects affecting our measurement. Our determination of the Eötvös ratio yields ηRb,K = −1.9 × 10−7 with a combined standard uncertainty of ση = 3.2 × 10−7. Graphical abstract

A model describing high-pressure adsorption based on the simplified local density model and the Bender equation of state is proposed. The Bender equation of state was used for the description of both bulk and adsorbed fluid. The model is capable of characterizing adsorbent material in terms of structural parameters such as the skeletal density, the micropore volume, and the energy of adsorption. The model was successfully applied to high-pressure adsorption isotherms of nitrogen and methane up to 50 MPa at 40 °C on a series of synthetic carbons and at 25-70 °C on the commercial carbon Norit R1. The structural parameters of the investigated carbons obtained by the proposed method are in good agreement with those obtained by independent methods based on standard and advanced characterization from nitrogen adsorption at 77 K.