Bose-Einstein condensation of K-41 and Rb-87 on an atom chip for sounding rocket missions

Im Rahmen dieser Arbeit wird die atomchipbasierte Experimentierkammer für den Einsatz in den Höhenforschungsraketenmissionen MAIUS-2 und 3 aufgebaut und mit einem bodengestützten System in Betrieb genommen. Die neue Apparatur ermöglicht innerhalb von 3.4 s die Erzeugung von Bose-Einstein-Kondensaten mit 3*10E5 Rb-87 Atomen oder 6*10E4 K-41 Atomen. Zusätzlich können quantenentartete Mischungen mit variablen Isotopenverhältnissen bereitgestellt werden. In Untersuchungen zur sympathetischen Kühlung von K-41 durch Rb-87 wird der Einfluss der Gravitation auf Thermalisierungsraten quantifiziert. Das Expansionsverhalten frei fallender Bose-Einstein-Kondensate wird für beide Isotope untersucht. Transiente Magnetfelder während des Ausschaltens der Magnetfalle zeigen dabei einen erheblichen Einfluss auf die Expansion und müssen in Simulationen berücksichtigt werden. Im Rahmen der Analyse kollektiver Anregungen reiner und gemischter Kondensate kann eine gegenseitige Dämpfung der Anregungen aufgrund der gegenseitigen Wechselwirkung aufgezeigt werden. Schließlich wird der Einfluss der Gravitation auf den Grundzustand und die Massenschwerpunktsbewegung der wechselwirkenden Ensembles durch Rotation der Apparatur in Flugzeitmessungen untersucht.This thesis presents the next generation atom chip apparatus for the sounding rocket missions MAIUS-2 and -3. With the new apparatus, Bose-Einstein condensates containing 3 · 10E5 atoms of Rb-87 or 6 · 10E4 atoms of K-41 are generated within 3.4 s in ground-based operation. In addition, quantum degenerate mixtures with variable isotope ratios can be provided. An analysis of sympathetic cooling of K-41 under the influence of gravity and prospects for thermalization rates in microgravity are given. The expansion dynamics of single species Bose-Einstein condensates released from a magnetic trap is analyzed in detail. It is shown that transient magnetic fields during trap switch-off have a considerable impact on the expansion dynamics. Further, collective excitations of single and mixed ensembles are evaluated. Due to interspecies damping, collective excitations of interacting mixtures of K-41 and Rb-87 are strongly suppressed. Finally, the influence of gravity on a trapped and strongly interacting mixture is observed via rotation of the whole apparatus.Deutsches Zentrum für Luft- und Raumfahrt/QUANTUS-IV-MAIUS/50WP1431/E

Role of boronic acid moieties in poly(amido amine)s for gene delivery

The effects of the presence of two different types of phenylboronic acids as side groups in disulfide-containing poly(amido amine)s (SS-PAA) were investigated in the application of these polymers as gene delivery vectors. To this purpose, a para-carboxyphenylboronic acid was grafted on a SS-PAA with pending aminobutyl side chains, resulting in p(DAB–4CPBA) and an ortho-aminomethylphenylboronic acid was incorporated through copolymerization, resulting in p(DAB–2AMPBA). Both polymers have 30% of phenylboronic acid side chains and 70% of residual aminobutyl side chains and were compared with the non-boronated benzoylated analogue p(DAB–Bz) of similar Mw. It was found that the presence of phenylboronic acid moieties improved polyplex formation with plasmid DNA since smaller and more monodisperse polyplexes were formed as compared to their non-boronated counterparts. The transfection efficiency of polyplexes of p(DAB–4CPBA) was approximately similar to that of p(DAB–Bz) and commercial PEI (Exgen), both in the absence and the presence of serum, indicating that p(DAB–4CPBA) and p(DAB–Bz) are potent gene delivery vectors. However, the polymers with phenylboronic acid functionalities showed increased cytotoxicity, which is stronger for the ortho-aminophenylboronic acid containing polyplexes of p(DAB–2AMPBA) than for the p(DAB–4CPBA) analog. The cytotoxic effect may be caused by increased membrane disruptive interaction as was indicated by the increased hemolytic activity observed for these polymers

Infrared spectroscopy of jet-cooled neutral and ionized aniline-Ar

We report the infrared (IR) absorption spectrum of the jet-cooled neutral aniline–Ar Van der Waals complex together with that of the aniline–Ar cation in the 350–1700 cm−1 range. The spectra are measured using mass-selective ion detection in two different IR–ultraviolet double-resonance excitation schemes, using a free-electron laser as a source of widely tunable, intense IR radiation. A comparison with calculated IR spectra of the bare neutral aniline and of the cation of aniline allows for an unambiguous assignment of all the observed modes. The dissociation limit of the neutral aniline–Ar complex is bracketed between 273 and 329 cm−1, significantly lower than previously estimated. <br

The infrared spectrum of the benzene–Ar cation

The infrared (IR) absorption spectra of the jet-cooled C6H6 and C6D6 cations, complexed with Ar, are measured throughout the 450–1500 cm−1 region via IR-laser-induced vibrational dissociation spectroscopy. The IR spectrum of the C6H6–Ar cation is dominated by a Fermi resonance between the IR active v11 mode and two components of the combination mode of the lowest frequency modes v6 and v16 . A stringent upper limit of 316 cm−1 is found for the value of the dissociation limit D0 of the neutral C6D6–Ar complex