Degenerate Quantum Gases in Microgravity

Clouds of ultra-cold atoms and especially Bose–Einstein condensates (BEC) provide a source for coherent matter-waves in numerous earth bound experiments. Analogous to optical interferometry, matter-wave interferometers can be used for precision measurements allowing for a sensitivity orders of magnitude above their optical counterparts. However, in some respects the presence of gravitational forces in the lab limits experimental possibilities. In this article, we report about a compact and robust experiment generating Bose–Einstein condensates in the drop tower facility in Bremen, Germany. We also present the progress of building the succeeding experiment in which a two species atom interferometer will be implemented to test the weak equivalence principle with quantum matter.     

Sorption behavior of the MgH2–Mg2FeH6 hydride storage system synthesized by mechanical milling followed by sintering

The hydrogen sorption behavior of the Mg₂FeH₆–MgH₂ hydride system is investigated via in-situ synchrotron and laboratory powder X-ray diffraction (SR-PXD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), particle size distribution (PSD) and volumetric techniques. The Mg₂FeH₆–MgH₂ hydride system is obtained by mechanical milling in argon atmosphere followed by sintering at high temperature and hydrogen pressure. In-situ SR-PXD results show that upon hydriding MgH₂ is a precursor for Mg₂FeH₆ formation and remained as hydrided phase in the obtained material. Diffusion constraints preclude the further formation of Mg₂FeH₆. Upon dehydriding, our results suggest that MgH₂ and Mg₂FeH₆ decompose independently in a narrow temperature range between 275 and 300 °C. Moreover, the decomposition behavior of both hydrides in the Mg₂FeH₆–MgH₂ hydride mixture is influenced by each other via dual synergetic-destabilizing effects. The final hydriding/dehydriding products and therefore the kinetic behavior of the Mg₂FeH₆–MgH₂ hydride system exhibits a strong dependence on the temperature and pressure conditions.     

Nanoconfinement degradation in NaAlH4/CMK-1

An ordered mesoporous carbon scaffold (CMK-1) has been synthesized and infiltrated with NaAlH₄ nanoparticles by solvent- and melt-infiltration techniques. Small angle X-ray scattering (SAXS), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM) and energy dispersive spectroscopy (EDS) are used to characterize the structure, composition and morphology before and after thermal treatment. This study illuminates some of the problems that can be associated with nanoconfinement of hydrogen storage materials including scaffold contamination, residual solvent contamination, sample morphology changes after heating, and other factors that can be detrimental to the application of these systems. Of particular interest is the expulsion of NaAlH₄ decomposition products from the scaffold after heating beyond its melting point under vacuum. This results in the surface of mesoporous carbon particles having arrays of multi-micron-long Al filaments that are >100 nm in diameter.     

Peptide profiles and angiotensin-I-converting enzyme inhibitory activity of fermented milk products: Effect of bacterial strain,fermentation pH,and storage time

Milk was fermented to defined pH values with 13 strains of lactic acid bacteria. The products were evaluated after 1 and 7 days of cold storage, and major peptides in selected products were identified. The Streptococcus thermophilus and Lactobacillus acidophilus strains used did not give rise to products with significant angiotensin-1-converting enzyme (ACE)-inhibition. The four Lactococcus lactis strains behaved similarly in fermentation, proteolysis and ACE-inhibition. The products made with the seven Lactobacillus helveticus strains varied. The highest ACE-inhibitory activity was obtained with two highly proteolytic strains of Lb. helveticus and with the Lactococcus strains. Fermentation from pH 4.6 to 4.3 with these strains slightly increased the ACE-inhibitory activity, whilst fermentation to pH 3.5 with Lb. helveticus reduced the ACE-inhibitory activity. Cold storage dramatically increased the ACE-inhibitory activity of some products. A non-linear correlation was found between peptide amount and ACE-inhibitory activity, and peptides contributing to the ACE-inhibitory activity were identified.     

Direct imaging by atomic force microscopy of surface-localized self-assembled monolayers on a cuprate superconductor and surface X-ray scattering analysis of analogous monolayers on the surface of water

A self-assembled monolayer of CF₃(CF₂)₃(CH₂)₁₁NH₂ atop the (001) surface of the high-temperature superconductor YBa₂Cu₃O_7-x was imaged by atomic force microscopy (AFM). The AFM images provide direct 2D-structural evidence for the epitaxial 5.5 Å square √2 × √2R45° unit cell previously predicted for alkyl amines by molecular modeling [J.E. Ritchie, C.A. Wells, J.-P. Zhou, J. Zhao, J.T. McDevitt, C.R. Ankrum, L. Jean, D.R. Kanis, J. Am. Chem. Soc. 120 (1998) 2733]. Additionally, the 3D structure of an analogous Langmuir monolayer of CF₃(CF₂)₉(CH₂)₁₁NH₂ on water was studied by grazing-incidence X-ray diffraction and specular X-ray reflectivity. Structural differences and similarities between the water-supported and superconductor-localized monolayers are discussed.     

Effects of smoking bans on passive smoking exposure at work and at home. The European Community respiratory health survey

This longitudinal study investigated whether smoking bans influence passive smoking at work and/or at home in the same subjects. Passive smoking at work and/or at home was investigated in random population samples (European Community Respiratory Health Survey) in 1990‐1995, with follow‐up interviews in 1998‐2003 and 2010‐2014. National smoking bans were classified as partial (restricted to public workplaces) or global (extended to private workplaces). Multivariable analysis was accomplished by three‐level logistic regression models, where level‐1, level‐2, and level‐3 units were, respectively, questionnaire responses, subjects, and centers. Passive smoking at work was reported by 31.9% in 1990‐1995, 17.5% in 1998‐2003, and 2.5% in 2010‐2014. Concurrently, passive smoking at home decreased from 28.9% to 18.2% and 8.8%. When controlling for sex, age, education, smoking status, and ECHRS wave, the odds of passive smoking at work was markedly reduced after global smoking bans (OR = 0.45, 95% CI 0.25‐0.81), particularly among non‐smokers, while the protective effect of global smoking bans on passive smoking at home was only detected in non‐smokers. Smoking bans both in public and private workplaces were effective in reducing passive smoking at work in Europe. However, given the inefficacy of smoking bans in current smokers’ dwellings, better strategies are needed to avoid smoking indoors.     

Do investments in flexibility enhance sustainability? A simulative study considering the German electricity sector

Current research concerning industrial demand side management primarily focuses on monetary aspects. Herein, we extend this perspective by assessing whether economically driven measures increasing the flexibility also result in reduced contributions to the residual load. For this purpose, we conduct a simulative study using historic and projected time series for the German electricity sector. First, Fourier analysis are performed to show that the main oscillation in the electricity price time series has a period length of 12 hr, whereas the renewable generation is primarily characterized by an oscillation with a period length of 24 hr. Second, a generic process model with capabilities for load shiftings is used to evaluate how the fluctuation patterns can be exploited via scheduling optimizations. Most importantly, our results demonstrate that prevalent price fluctuations prevent adequate monetary incentives for providing storage capacities for bridging up to 24 hr, which are desired for reducing the residual load.