Synthesis of thymosin β4Xen and its comparison with the natural tritetraconpeptide

Thymosin β₄^Xen, a 43 residue peptide recently isolated from Xenopus laevis, was synthesized by automatic solid phase procedure and compared with the natural product, isolated from the ovaries of Xenopus laevis For the synthesis N-methylpyrrolidone was chosen as solvent instead of the commonly used dimethylformamide because this solvent seems to be superior for solid phase peptide synthesis due to the favorable swelling properties of the polystyrene resin in this solvent and its dissolving power against the resin-bound peptide which reduces intermolecular aggregation. With acetic anhydride/pyridine and hydroxysuccinimide acetate two different acetylation reagents were tested for the final acetylation step, which gave both comparable results as shown by analytical HPLC investigations. The crude synthetic product was purified by HPLC, confirmed by ASA and LD-MS and was identical compared with the natural thymosin β₄^Xen     

A Peroxygenase-Alcohol Dehydrogenase Cascade Reaction to Transform Ethylbenzene Derivatives into Enantioenriched Phenylethanols

In this study, we developed a new bienzymatic reaction to produce enantioenriched phenylethanols. In a first step, the recombinant, unspecific peroxygenase from Agrocybe aegerita (rAaeUPO) was used to oxidise ethylbenzene and its derivatives to the corresponding ketones (prochiral intermediates) followed by enantioselective reduction into the desired (R)- or (S)-phenylethanols using the (R)-selective alcohol dehydrogenase (ADH) from Lactobacillus kefir (LkADH) or the (S)-selective ADH from Rhodococcus ruber (ADH-A). In a one-pot two-step cascade, 11 ethylbenzene derivatives were converted into the corresponding chiral alcohols at acceptable yields and often excellent enantioselectivity.     

Assessment of low-frequency aeroacoustic emissions of a wind turbine under rapidly changing wind conditions based on an aero-servo-elastic CFD simulation

A meteorologically challenging situation that represents a demanding control task (rotational speed, pitch and yaw) for a wind turbine is presented and its implementation in a simulation is described. A high-fidelity numerical process chain, consisting of the computational fluid dynamics (CFD) solver FLOWer, the multi-body system (MBS) software SIMPACK and the Ffowcs Williams-Hawkings code ACCO, is used. With it, the aerodynamic, servoelastic and aeroacoustic (<20 Hz) behaviour of a generic wind turbine during a meteorological event with strong and rapid changes in wind speed and direction is investigated. A precursor simulation with the meteorological model system PALM is deployed to generate realistic inflow data. The simulated strong controller response of the wind turbine and the resulting aeroelastic behaviour are analysed. Finally, the low-frequency sound emissions are evaluated and the influence of the different operating and flow parameters during the variable inflow is assessed. It is observed that the wind speed and, linked to it, the rotational speed as well as the turbulence intensity are the main influencing factors for the emitted low-frequency sound power of the wind turbine. Yawed inflow, on the other hand, has little effect unless it changes the operational mode to load reduction, resulting in a swap of the main emitter from the blades to the tower.