Andrea I. Schäfer

Nov 29, 2024 | sciencedirect.com | Bin Xu |MINH NGUYEN |Minh Nguyễn |Andrea Schafer |Andrea I. Schäfer |Wenya Lu

The progress in military equipment technology has sparked the creation of cutting-edge tactical missiles, necessitating the enhancement of their capabilities to stay ahead in the evolving battlefield landscape. These missiles used fuel-rich propellants as the driving force of solid rocket ramjet engines, which ingeniously utilized the ambient oxidizing agent to deliver extra specific impulses, breathtaking velocities and unprecedented ranges.

Feb 6, 2024 | nature.com | Andrea I. Schäfer |Melinda L. Jue |Sei Jin Park |Florian Vollnhals |Minh N. Nguyen |Francesco Fornasiero | +2 more

Vertically-aligned carbon nanotube (VaCNT) membranes allow water to conduct rapidly at low pressures and open up the possibility for water purification and desalination, although the ultralow viscous stress in hydrophobic and low-tortuosity nanopores prevents surface interactions with contaminants. In this experimental investigation, steroid hormone micropollutant adsorption by VaCNT membranes is quantified and explained via the interplay of the hydrodynamic drag and friction forces acting on the hormone, and the adhesive and repulsive forces between the hormone and the inner carbon nanotube wall. It is concluded that a drag force above 2.2 × 10−3 pN overcomes the friction force resulting in insignificant adsorption, whereas lowering the drag force from 2.2 × 10−3 to 4.3 × 10−4 pN increases the adsorbed mass of hormones from zero to 0.4 ng cm−2. At a low drag force of 1.6 × 10−3 pN, the adsorbed mass of four hormones is correlated with the hormone−wall adhesive (van der Waals) force. These findings explain micropollutant adsorption in nanopores via the forces acting on the micropollutant along and perpendicular to the flow, which can be exploited for selectivity. Micropollutant removal in polymeric nanofiltration membranes is difficult to characterise due to pore heterogeneity. A force interplay framework was developed to describe adsorption in VaCNT membranes with defined nanopores, providing insight for the design of membranes with improved selectivity.

Jul 16, 2023 | zdf.de | Andrea I. Schäfer

Noch ist der Wiederaufbau im Ahrtal nicht abgeschlossen. Dennoch will die Region mit einem nachhaltigen Tourismuskonzept für Urlauber wieder attraktiv werden. Die Flutkatastrophe im Ahrtal im Jahr 2021 hat nicht nur 135 Menschenleben gekostet, sondern auch einen ganzen Wirtschaftszweig hart getroffen: den Tourismus.