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ABSTRACT Ethyl acetate is at present exclusively produced from fossil resources. Microbial synthesis of this ester from sugar‐rich waste as an alternative is an aerobic process. Ethyl acetate is highly volatile and therefore stripped with the exhaust gas from the bioreactor which enables in situ product recovery. Previous research on microbial formation of ethyl acetate has focused on the kinetics of ester synthesis and in part on the ester stripping, while the separation of the ester from the exhaust gas has hardly been investigated. A mixed matrix membrane was developed consisting of Silikalite‐1 embedded in polydimethylsiloxane which was installed in a radial–symmetrical membrane module. Evaluation of the separation of ethyl acetate was based on the analysis of the composition of the feed and retentate gas by mass spectrometry. The separation efficiency of the membrane was first tested with varied flows of artificial exhaust gas, containing defined amounts of ethyl acetate. A model for describing the separation process was parametrized by the measured data and used to design a real separation experiment. Ethyl acetate produced from delactosed whey permeate by Kluyveromyces marxianus DSM 5422 in a stirred bioreactor gassed with 0.5 vvm air was successfully separated from the exhaust gas by membranes; 93.6% of the stripped ester was separated. Liquid ethyl acetate was recovered by cooling the permeate gas to ‒78°C, whereby 99.75% of the condensed organic compounds were ethyl acetate. This study demonstrates for the first time that microbially produced and stripped ethyl acetate can be effectively separated from the exhaust gas of bioreactors by membrane technology to obtain the ester in high yield and purity.

To guarantee sufficient surge current fault protection for power electronic converters, power semiconductors have to be tested under appropriate surge current conditions. Standard maximum surge current values include the permissible fault current amplitude, or the I2t-value; however, they might not be sufficient to describe a power semiconductor's performance under all potential fault conditions. Surge current sources based on passive components are state-of-the-art, but are limited to usually only one specific current waveform. This article describes the topology and the design of a new modular and highly dynamic surge current source for power semiconductor tests with adjustable current waveforms. The new modular converter concept is introduced, with two potential operation modes: High current mode (HCM) and dynamic current mode (DCM). The requirements for the surge current tester are defined, and the electrical and mechanical design are described, including the modulation scheme and control. Experimental investigations prove the function of the current source with peak currents up to 100 kA (HCM) and the realization of highly dynamic load current trajectories with peak currents up to 50 kA (DCM). The output current ripple is exceptionally small with a theoretical value of below 1%.

Photocathode laser pulse shaping is a crucial technology for enhancing the performance of X-ray free-electron lasers by optimizing the quality of electron beams generated from photocathodes within high-gradient radio frequency guns. By precisely shaping these laser pulses, it is possible to significantly reduce the transverse emittance of produced electron bunches. The optimal pulse shape is an ellipsoidal distribution, commonly referred to as the Kapchinskij–Vladimirskij profile. A pulse-shaping scheme utilizing a commercial Yb:KGW laser operating at 514 nm with a repetition rate of 1 MHz and duration of 260 fs has been developed for generating electron bunches with high peak and average power. This study presents the experimental realization of ellipsoidal pulses via three-dimensional amplitude shaping using spatial light modulators at 514 nm, followed by conversion to UV (257 nm) suitable for Cs 2Te photocathodes. The preservation of pulse shape and a high conversion efficiency during this process are investigated and our experiments pave the way for future emittance minimization for X-ray free-electron lasers.

A key issue of X-ray free-electron lasers is the quality of the photoelectron beams generated from a photocathode by laser pulses in the high-gradient RF gun. Controlling the shape of these laser pulses can strongly reduce the transverse emittance of the generated electron bunch. For this purpose, a laser pulseshaper at 515 nm is presented that can be used directly with alkali antimonide photocathodes for photoemission. The first results regarding generation and measurement of flattop and parabolic pulses as well as introduction of modulations for THz generation are presented and show the potential for emittance optimization with 3D ellipsoidal pulses with the proposed pulseshaper. The experiments are carried out for Cs2Te photocathodes, which require second harmonic generation of the shaped pulses and thus allow investigation of pulseshape preservation in nonlinear frequency conversion processes.

Abstract Ethyl acetate is currently produced from fossil carbon resources. This ester could also be microbially synthesized from sugar‐rich wastes of the food industry. Wild‐type strains with GRAS status are preferred for such applications. Production of ethyl acetate by wild‐type yeasts has been repeatedly reported, but comparative studies with several strains at various induction modes are largely missing. Here, synthesis of ethyl acetate by three yeasts with GRAS status, Kluyveromyces marxianus DSM 5422, Cyberlindnera jadinii DSM 2361 and Wickerhamomyces anomalus DSM 6766, was studied under identical and well‐defined conditions in an aerated bioreactor, by inducing the ester synthesis via iron or oxygen limitation. Balancing the ester synthesis was based on measured concentrations of ethyl acetate in the exhaust gas, delivering masses of synthesized ester and synthesis rates in a high temporal resolution. All tested yeasts synthesized ethyl acetate under these conditions, but the intensity varied with the strain and induction mode. The highest yields were achieved under iron limitation with K. marxianus (0.182 g g–1) and under oxygen limitation with W. anomalus (0.053 g g–1). Iron limitation proved to be the better inducer for ester synthesis while oxygen limitation favored ethanol formation. K. marxianus DSM 5422 was the most potent producer of ethyl acetate exhibiting the highest biomass‐specific synthesis rate of 0.5 g g–1h–1 under moderate iron limitation.

Abstract Ethyl acetate is an organic solvent with many industrial applications, currently produced by energy‐intensive chemical processes based on fossil carbon resources. Ethyl acetate can be synthesized from renewable sugars by yeasts like Kluyveromyces marxianus in aerobic processes. However, ethyl acetate is highly volatile and thus stripped from aerated cultivation systems which complicate the quantification of the produced ester. Synthesis of volatile metabolites is commonly monitored by repeated analysis of metabolite concentrations in both the gas and liquid phase. In this study, a model‐based method for quantifying the synthesis and degradation of volatile metabolites was developed. This quantification of volatiles is solely based on repeatedly measured gas‐phase concentrations and allows calculation of reaction rates and yields in high temporal resolution. Parameters required for these calculations were determined in abiotic stripping tests. The developed method was validated for ethyl acetate, ethanol and acetaldehyde which were synthesized by K. marxianus DSM 5422 during an iron‐limited batch cultivation; it was shown that the presented method is more precise and less time‐consuming than the conventional method. The biomass‐specific synthesis rate and the yield of ethyl acetate varied over time and exhibited distinct momentary maxima of 0.50 g g‒1h‒1 and 0.38 g g‒1 at moderate iron limitation.

Finding the lowest energy configuration of N unit charges on a sphere, known as Thomson's problem, is a long-standing query which has only been studied via numerical simulations. We present its physical realization using multiply charged He nanodroplets. The charge positions are determined by x-ray coherent diffractive imaging with Xe as a contrast agent. In neutral droplets, filaments resulting from Xe atoms condensing on quantum vortices are observed. Unique to charged droplets, however, Xe clusters that condense on charges are distributed on the surface in lattice-like structures, introducing He droplets as experimental model systems for the study of Thomson's problem.

Positionierungen und Selbstdeutungen von Dozierenden in der Lehrpersonenbildung waren in der Vergangenheit sowohl ortsspezifisch geprägt als auch in einen Strom unterschiedlichen pädagogischen Wissens eingebunden. Es stellen sich in einer historischen Spurensuche – mit kurzen Quellensondierungen zu verschiedenen Zeitabschnitten im 20. Jahrhundert zu Positionierungen von Lehrpersonenbildner*innen – vielfältige Fragen im Zusammenhang mit „Normalmodellen“, mit wissenschaftlich-disziplinären Orientierungen, mit der Kritik an der disziplinären Arbeitsteilung in der Wissensproduktion und mit Erziehungsidealen. Das Essay soll auf der Grundlage historisch-konzepthafter Schriften aus dem deutschen und deutschschweizerischen Bildungsraum zur Ausbildung von Lehrpersonen, zum Hochschulunterricht und zur Hochschulreform – irritierend und ordnungsstiftend zugleich – zu einer Diskussion einladen, die sensibel für Paradoxien ist. Der Beitrag soll in einer kulturhistorisch informierten Perspektive den Blick schärfen für ambivalente und paradoxal anmutende Deutungen zur Pluralität in den wissenschaftlichen Perspektiven von Dozierenden und hochschulpolitischen Akteur*innen, die mit der Suche nach „Synthetisierungen“ teilweise auch Nähen zum Antiakademismus aufweisen konnten. Es wird aufgezeigt, unter welchen Voraussetzungen die Rede vom angelsächsischen Erziehungsideal hinsichtlich der Lehrpersonenbildung einer analytischen Unschärfe Vorschub leisten konnte. Vor dem Hintergrund dieser historischen Selbstbefremdung beschließt ein Ausblick auf allfällige Kategorienverwechslungen in der gegenwärtig häufig vorgetragenen Schulpraxiserfordernis von Dozierenden in der Lehrpersonenbildung die Überlegungen.

Carbon nanofibers are produced from dielectric polymer precursors such as polyacrylonitrile (PAN). Carbonized nanofiber nonwovens show high surface area and good electrical conductivity, rendering these fiber materials interesting for application as electrodes in batteries, fuel cells, and supercapacitors. However, thermal processing is slow and costly, which is why new processing techniques have been explored for carbon fiber tows. Alternatives for the conversion of PAN-precursors into carbon fiber nonwovens are scarce. Here, we utilize an atmospheric pressure plasma jet to conduct carbonization of stabilized PAN nanofiber nonwovens. We explore the influence of various processing parameters on the conductivity and degree of carbonization of the converted nanofiber material. The precursor fibers are converted by plasma-jet treatment to carbon fiber nonwovens within seconds, by which they develop a rough surface making subsequent surface activation processes obsolete. The resulting carbon nanofiber nonwovens are applied as supercapacitor electrodes and examined by cyclic voltammetry and impedance spectroscopy. Nonwovens that are carbonized within 60 s show capacitances of up to 5 F g−1.

One of the key demands on tungsten (W) as designated plasma-facing material (PFM) is the capability to fulfill a structural function. Since W has refused ductilization strategies by alloying alone, the production of W materials with enhanced ductility has come into focus considering tailored microstructures. This work addresses the rolling-induced microstructural modifications of warm- and cold-deformed W sheets and is supplemented by a comprehensive fracture mechanical study as a fundament for correlations between the spatial distribution of boundaries and brittle-to-ductile transition (BDT) temperature. Here we show that an extended Hall–Petch-like relationship is well suited to describe the rolling-induced reduction in BDT temperature and moreover has the potential to reflect the anisotropic nature of the transition temperature in severely rolled W sheets. Using the data of warm- and cold-rolled W sheets and also of strongly recovered W, best description of the BDT temperature was achieved by using as microstructural variables (i) the mean spacing between boundaries which intersect with the crack front and (ii) the mean boundary spacing along the normal of the crack plane. Taking into account the similarity to recent simulative-derived relationships, our findings support the theory suggesting the stimulated dislocation nucleation at boundaries as the decisive factor for more effective shielding of the crack tip in UFG materials and, in consequence, significantly reduced BDT temperatures. Besides, this work gives strong indications that the reduction of the BDT temperature in UFG W is not related to coincidence site lattice (CSL) boundaries.

Due to unique properties, antiresonant hollow core fibers have found widespread use in various fields of science and application. Particular regarding applications that involve ultrashort pulses, precise knowledge of group velocity dispersion is essential to understand the underlying physics and to optimize device performance. Here we report on the successful measurement of the spectral distribution of the group velocity dispersion of the fundamental mode of an antiresonant hollow core fiber in close proximity to and away from a strong strand resonance. The results show the variations of the hundreds of fs2/cm near the resonance region, whereas the dispersion is identical to that of a perfect cylindrical waveguide away from the resonance in accordance with a literature. An additional zero dispersion wavelength that is not present in the case of a capillary was experimentally verified. The possibility to tune dispersion via strand resonances opens up a novel pathway towards engineering pulse dispersion, with applications in fields such as nonlinear science and pulse propagation management.

The synthesis of transition metal oxynitrides is complicated by extreme reaction conditions such as high temperatures and/or high pressures. Here, we show an unprecedented solution-based synthesis of narrowly dispersed titanium oxynitride nanoparticles of cubic shape and average size of 65 nm. Their synthesis is performed by using titanium tetrafluoride and lithium nitride as precursors alongside trioctylphosphine oxide (TOPO) and cetrimonium bromide (CTAB) as stabilizers at temperatures as low as 250 °C. The obtained nanoparticles are characterized in terms of their shape and optical properties, as well as their crystalline rock-salt structure, as confirmed by XRD and HRTEM analysis. We also determine the composition and nitrogen content of the synthesized particles using XPS and EELS. Finally, we investigate the applicability of our titanium oxynitride nanoparticles by compounding them into carbon fiber electrodes to showcase their applicability in energy storage devices. Electrodes with titanium oxynitride nanoparticles exhibit increased capacity compared to the pure carbon material.

We report about a case of a compassionate off-label use of the anti-interleukin-5-agent mepolizumab in a ventilated patient with life-threatening asthma attack in eosinophilic asthma. The patient suffered from severe eosinophilic asthma and was transmitted to our hospital with an asthma attack and a life-threatening respiratory state under ventilation. Since high dose steroids had not yielded a sufficient respiratory improvement mepolizumab was administered subcutaneously. After administration of mepolizumab respiratory state and ventilation parameter improved significantly. Two days after administration the patient was weaned could be extubated 8 days later and recovered completely from the asthma attack.The presented clinical case is suggestive of future clinical trials or registry studies to evaluate potential clinical benefits of anti-interleukin-5 treatment in patients with severe exacerbations of eosinophilic asthma. Keywords: Anti-IL-5-therapy, Asthma, Eosinophilia, Exacerbation, Intensive care medicine

In this contribution we present a comparison of the performance of spectrally broadened ultrashort pulses using a hollow-core fiber either filled with argon or sulfur hexafluoride (SF6) for demanding pulse-shaping experiments. The benefits of both gases for pulse-shaping are studied in the highly nonlinear process of high-harmonic generation. In this setup, temporally shaping the driving laser pulse leads to spectrally shaping of the output extreme ultraviolet (XUV) spectrum, where total yield and spectral selectivity in the XUV are the targets of the optimization approach. The effect of using sulfur hexafluoride for pulse-shaping the XUV yield can be doubled compared to pulse compression and pulse-shaping using argon and the spectral range for selective optimization of a single harmonic can be extended. The obtained results are of interest for extending the range of ultrafast science applications drawing on tailored XUV fields.

The monothematic issue of Pedagogika, Historical Reflection of Education and Its Significance in (Not Only) Teacher Education, tackles several questions and problematic areas at a time.

Abstract: Th is paper focuses on the use of history and historical fi gures within the scope of pedagogy and didactics in teacher education, especially in textbooks and writings of teacher educators. In the analyzed texts, the present time is often diagnosed to be decadent whereas the past is imagined as a golden age. Historical fi gures and references to history were used as a pool of eternal truths which were credited with the ability to point the way to a better future. An eclectic choice of historical aspects usually was merged with modern scientifi c fi ndings into scientifi c text formats. Th e scientifi c aspect itself as well as dignity and ability to provide guidance ascribed to the historical fi gures conferred legitimation and authority to the texts produced by the teacher educators. Keywords: teacher training, history, pedagogical textbooks, classical authors, community, critique of schools, school reforms.

Stereolithography is one of the most promising technologies for the production of tailored implants. Within this study, we show the results of a new resin formulation for three-dimensional printing which is also useful for subsequent surface functionalization. The class of materials is based on monomers containing either thiol or alkene groups. By irradiation of the monomers at a wavelength of 266 nm, we demonstrated an initiator-free stereolithographic process based on thiol-ene click chemistry. Specimens made from this material have successfully been tested for biocompatibility. Using Fourier-transform infrared spectrometry and fluorescent staining, we are able to show that off-stoichiometric amounts of functional groups in the monomers allow us to produce scaffolds with functional surfaces. We established a new protocol to demonstrate the opportunity to functionalize the surface by copper-catalyzed azide-alkyne cycloaddition chemistry. Finally, we demonstrate a three-dimensional bioprinting concept for the production of potentially biocompatible polymers with thiol-functionalized surfaces usable for subsequent functionalization.

It is one fundamental conviction of ancient philosophy that, in contrast to the vast majority, only few are able to gain knowledge of truth. This axiom, which also underlies Cicero’s Hortensius, is adapted by the young Augustine. When looking for a concept of truth that combines the ideal of a philosophical existence with Christianity, he decides to join the Manichaeans. As opposed to the ‘mainline church’ of the catholica in which ‘the many’ are gathered, the Manichaeans appear to him as a small, elitist Christian community meeting higher intellectual as well as ethical demands. This claim seems to be particularly and impressively confirmed by the ‘pauci electi’. Their approach has apparently strengthened Augustine’s belief that true, higher Christianity is to be found amongst the Manichaeans. When he later devotes himself to the catholica and leads the fight against the Manichaeans, Augustine adheres to the conviction of the ‘few wise’. Also within the catholica only few attain maximum insight and lead an appropriate life. At the same time, however, Augustine increasingly considers ‘the many’ as positive. These two aspects are combined in his epistemological concept of ‘auctoritas’: by means of their auctoritas, the few ‘wise’ within the Catholic Church are supposed to guide the many towards truth on their journey of faith and cause them to improve their moral conduct. Its big success is a major argument for the catholica, whilst the ‘paucitas’ of the Manichaeans (and all heretics) can be considered evidence of the groundlessness and absurdity of their doctrine.

Gestützt auf Archivalien der EDK befasst sich der Beitrag mit den Reformversuchen der Lehrpersonenausbildung für die Sekundarstufe I bzw. Volksschuloberstufe in der zweiten Hälfte des 20. Jahrhunderts in der deutschsprachigen Schweiz. Die Themen Akademisierung, universitäre Verortung und Schulstufenorientierung bildeten eine Konfliktlinie, welche die kantonalen an Schultypen angelehnten tradierten Ausbildungsstrukturen irritierte. In den bildungshistorischen Rekonstruktionen zeigt sich, dass sowohl die Reforminitianten als auch die Reformkritiker bemüht waren, ihre Positionen mit wissenschaftlicher Expertise zu untermauern. Vor dem Hintergrund einer Dokumentenanalyse gelangt der Beitrag zur Einschätzung, dass wissenschaftliche Bezugnahme allein nicht ausreichte, um einen Systemwechsel in der Lehrpersonenausbildung herbeizuführen.

In this contribution, we present a wavelength-sensitive method for the detection of extreme ultraviolet (XUV) photon energies between 30 eV and 120 eV. The method is based on 45° reflectivity from either a cesium iodide-coated or an uncoated metal surface, which directs the XUV beam onto an electron or ion detector and its signal is used to monitor the XUV beam. The benefits of our approach are a spectrally sensitive diagnosis of the XUV radiation at the interaction place of time-resolved XUV experiments and the detection of infrared leak light though metal filters in high-harmonic generation (HHG) experiments. Both features were tested using spectrally shaped XUV pulses from HHG in a capillary, and we have achieved excellent agreement with XUV spectrometer measurements and reflectivity calculations. Our obtained results are of interest for time-resolved XUV experiments presenting an additional diagnostic directly in the interaction region and for small footprint XUV beamline diagnostics.

A variety of approaches have been employed to generate binding proteins from non-antibody scaffolds. Utilizing a beta-sheet of the human ubiquitin for paratope creation we obtained binding proteins against tumor necrosis factor (TNF)-alpha. The bioactive form of this validated pharmacological target protein is a non-covalently linked homo-trimer. This structural feature leads to the observation of a certain heterogeneity concerning the binding mode of TNF-alpha binding molecules, for instance in terms of monomer/trimer specificity. We analyzed a ubiquitin-based TNF-alpha binder, selected by ribosome display, with a particular focus on its mode of interaction. Using enzyme-linked immunosorbent assays, specific binding to TNF-alpha with nanomolar affinity was observed. In isothermal titration calorimetry we obtained comparable results regarding the affinity and detected an exothermic reaction with one ubiquitin-derived binding molecule binding one TNF-alpha trimer. Using NMR spectroscopy and other analytical methods the 1:3 stoichiometry could be confirmed. Detailed binding analysis showed that the interaction is affected by the detergent Tween-20. Previously, this phenomenon was reported only for one other type of alternative scaffold-derived binding proteins--designed ankyrin repeat proteins--without further investigation. As demonstrated by size exclusion chromatography and NMR spectroscopy, the presence of the detergent increases the association rate significantly. Since the special architecture of TNF-alpha is known to be modulated by detergents, the access to the recognized epitope is indicated to be restricted by conformational transitions within the target protein. Our results suggest that the ubiquitin-derived binding protein targets a new epitope on TNF-alpha, which differs from the epitopes recognized by TNF-alpha neutralizing antibodies.