@article{GuentzelSchillingHanioetal.2020,
  author    = {G{\"u}ntzel, Paul and Schilling, Klaus and Hanio, Simon and Schlauersbach, Jonas and Schollmayer, Curd and Meinel, Lorenz and Holzgrabe, Ulrike},
  title     = {Bioinspired Ion Pairs Transforming Papaverine into a Protic Ionic Liquid and Salts},
  series = {ACS Omega},
  volume    = {5},
  journal   = {ACS Omega},
  number    = {30},
  doi       = {10.1021/acsomega.0c02630},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230265},
  pages     = {19202-19209},
  year      = {2020},
  abstract  = {Microbial, mammalian, and plant cells produce and contain secondary metabolites, which typically are soluble in water to prevent cell damage by crystallization. The formation of ion pairs, for example, with carboxylic acids or mineral acids, is a natural blueprint to maintain basic metabolites in solution. Here, we aim at showing whether the mostly large carboxylates form soluble protic ionic liquids (PILs) with the basic natural product papaverine resulting in enhanced aqueous solubility. The obtained PILs were characterized by H-1-N-15 HMBC nuclear magnetic resonance (NMR) and in the solid state using X-ray powder diffraction, differential scanning calorimetry, and dissolution measurements. Furthermore, their supramolecular pattern in aqueous solution was studied by means of potentiometric and photometrical solubility, NMR aggregation assay, dynamic light scattering, zeta potential, and viscosity measurements. Thereby, we identified the naturally occurring carboxylic acids, citric acid, malic acid, and tartaric acid, as being appropriate counterions for papaverine and which will facilitate the formation of PILs with their beneficial characteristics, like the improved dissolution rate and enhanced apparent solubility.},
  language  = {en}
}
@article{KramerBangertSchilling2020,
  author    = {Kramer, Alexander and Bangert, Philip and Schilling, Klaus},
  title     = {UWE-4: First Electric Propulsion on a 1U CubeSat — In-Orbit Experiments and Characterization},
  series = {Aerospace},
  volume    = {7},
  journal   = {Aerospace},
  number    = {7},
  doi       = {10.3390/aerospace7070098},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236124},
  year      = {2020},
  abstract  = {The electric propulsion system NanoFEEP was integrated and tested in orbit on the UWE-4 satellite, which marks the first successful demonstration of an electric propulsion system on board a 1U CubeSat. In-orbit characterization measurements of the heating process of the propellant and the power consumption of the propulsion system at different thrust levels are presented. Furthermore, an analysis of the thrust vector direction based on its effect on the attitude of the spacecraft is described. The employed heater liquefies the propellant for a duration of 30 min per orbit and consumes 103 ± 4 mW. During this time, the respective thruster can be activated. The propulsion system including one thruster head, its corresponding heater, the neutralizer and the digital components of the power processing unit consume 8.5 ± 0.1 mW ⋅μ A\(^{-1}\) + 184 ± 8.5 mW and scales with the emitter current. The estimated thrust directions of two thruster heads are at angles of 15.7 ± 7.6∘ and 13.2 ± 5.5∘ relative to their mounting direction in the CubeSat structure. In light of the very limited power on a 1U CubeSat, the NanoFEEP propulsion system renders a very viable option. The heater of subsequent NanoFEEP thrusters was already improved, such that the system can be activated during the whole orbit period.},
  language  = {en}
}