93 research outputs found
Der Konsens ist zerbrochen. Die (kirchliche) Diskussion um den moralischen Status des Embryos
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Nocturnal energy demand in plants: insights from studying mutants impaired in β-oxidation
No full textFatty acid beta-oxidation is essential for seedling establishment of oilseed plants, but little is known about its role in leaf metabolism of adult plants. Arabidopsis thaliana plants with loss-of-function mutations in the peroxisomal ABC-transporter1 (PXA1) or the core beta-oxidation enzyme keto-acyl-thiolase 2 (KAT2) have impaired peroxisomal beta-oxidation. pxa1 and kat2 plants developed severe leaf necrosis, bleached rapidly when returned to light, and died after extended dark treatment, whereas the wild type was unaffected. Dark-treated pxa1 plants showed a decrease in photosystem II efficiency early on and accumulation of free fatty acids, mostly alpha-linolenic acid [18:3(n-3)] and pheophorbide a, a phototoxic chlorophyll catabolite causing the rapid bleaching. Isolated wild-type and pxa1 chloroplasts challenged with comparable alpha-linolenic acid concentrations both showed an 80% reduction in photosynthetic electron transport, whereas intact pxa1 plants were more susceptible to the toxic effects of alpha-linolenic acid than the wild type. Furthermore, starch-free mutants with impaired PXA1 function showed the phenotype more quickly, indicating a link between energy metabolism and beta-oxidation. We conclude that the accumulation of free polyunsaturated fatty acids causes membrane damage in pxa1 and kat2 plants and propose a model in which fatty acid respiration via peroxisomal beta-oxidation plays a major role in dark-treated plants after depletion of starch reserves
Quaternäre Legierungen MnFePtAl, MnFePtGa, MnFePdAl, MnFePdGa: Synthese, Phasenanalyse, mirkrostrukturelle Charakterisierung und magnetische Eigenschaften
No full textThe Potassium Transporter AtHAK5 Functions in K+ Deprivation-Induced High-Affinity K+ Uptake and AKT1 K+ Channel Contribution to K+ Uptake Kinetics in Arabidopsis Roots
No full textLaser-induced activation of Mg-doped GaN: quantitative characterization and analysis
No full textWe investigate the effectiveness of laser-induced treatment as compared to rapid-thermal annealing (RTA) for the activation of p-type dopant in Mg-doped GaN layers. The study is based on a wide set of analytical techniques, including resistivity measurements, atomic force microscopy, scanning emission microscopy (SEM), dynamic secondary ion mass spectroscopy (D-SIMS), time-of-flight (TOF) SIMS and energy dispersive X-ray spectroscopy (EDXS) in combination with scanning transmission electron microscopy (STEM). Samples are treated at different energy densities and in different atmospheres, to provide a comprehensive overview of the topic. The analysis is carried out on GaN-on-Si samples, to demonstrate the effectiveness of the treatment even in presence of high threading dislocation densitie
C8.4 Measurement Methods for Understanding Water Uptake Processes in Polymers
No full textS.306-307Harsh environmental conditions may cause corrosion processes in electronics. They are mainly induced by water uptake of polymer embedding, housing or molding compounds. Therefore, longtime stability of these materials is critical for many applications. This work is focusing on demonstration and discussion of suitable measurement methods to determine the water uptake of polymers. Electrochemical impedance spectroscopy (EIS) and Fourier Transform Infrared spectroscopy (FTIR) were used to investigate polymer degradation before and after multiple loading scenarios. Degradation models could have been derived from these results
Der Konsens ist zerbrochen. Die (kirchliche) Diskussion um den moralischen Status des Embryos
No full textA Dynamic Silver(I) Nanocluster Holds Together a 3 × 3 Self-Assembled Grid
No full textMetal ions with well-defined coordination geometries can serve as fixed joints within self-assembled architectures, defining the relative orientations of ligands within higher-order superstructures. The exchange of ligands and metal ions between different positions is slow, involving disruption or distortion. Here we report a series of AgI12X4L6 3 × 3 metal–organic grid-like structures, where the core AgI12X4 nanocluster is in dynamic motion, with AgI ions moving between different binding sites, with concomitant conformational changes of the organic ligands, which continue to occupy well-defined positions nevertheless. The identity of the incorporated halide anion governs the activation barrier for silver ion exchange, thus enabling rate control in response to two distinct stimuli: by changing the temperature, and by exchanging one halide for another. The dynamic nanocluster within these grids thus provides a new mode of using metal ions in coordination-driven self-assembly, establishing that the mobile AgI ions behave in similar ways to Ag0 atoms in surface-bound clusters and in silver nanoparticles. The kinetic parameters determined in this work, and the techniques developed to measure them, could serve the scientific community to provide additional insight into dynamic metal nanoclusters
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Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation
No full textAlpine heavy precipitation events often affect small catchments, although the circulation pattern leading to the event extends over the entire North Atlantic. The various scale interactions involved are particularly challenging for the numerical weather prediction of such events. Unlike previous studies focusing on the southern Alps, here a comprehensive study of a heavy precipitation event in the northern Alps in October 2011 is presented with particular focus on the role of the large-scale circulation in the North Atlantic/European region. During the event exceptionally high amounts of total precipitable water occurred in and north of the Alps. This moisture was initially transported along the flanks of a blocking ridge over the North Atlantic. Subsequently, strong and persistent northerly flow established at the upstream flank of a trough over Europe and steered the moisture towards the northern Alps. Lagrangian diagnostics reveal that a large fraction of the moisture emerged from the West African coast where a subtropical upper-level cut-off low served as an important moisture collector. Wave activity flux diagnostics show that the ridge was initiated as part of a low-frequency, large-scale Rossby wave train while convergence of fast transients helped to amplify it locally in the North Atlantic. A novel diagnostic for advective potential vorticity tendencies sheds more light on this amplification and further emphasizes the role of the ridge in amplifying the trough over Europe. Operational forecasts misrepresented the amplitude and orientation of this trough.
For the first time, this study documents an important pathway for northern Alpine flooding, in which the interaction of synoptic-scale to large-scale weather systems and of long-range moisture transport from the Tropics are dominant. Moreover, the trapping of moisture in a subtropical cut-off near the West African coast is found to be a crucial precursor to the observed European high-impact weather
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