37 research outputs found
First order phase transition from ferromagnetism to antiferromagnetism in Ce(FeAl)
Taking the pseudobinary C15 Laves phase compound
Ce(FeAl) as a paradigm for studying a ferromagnetic to
antiferromagnetic phase transition, we present interesting thermomagnetic
history effects in magnetotransport as well as magnetisation measurements
across this phase transition. A comparison is made with history effects
observed across the ferromagnetic to antiferromagnetic transition in
RSrMnO crystals.Comment: 11 pages of text and 4 figures; submitted to Physical Review Letter
Resistance of the Lichen Buellia frigidato Simulated Space Conditions during the Preflight Tests for BIOMEX—Viability Assay and Morphological Stability
Samples of the extremotolerant Antarctic endemite lichen Buellia frigida are currently exposed to low-Earth orbit–
space and simulated Mars conditions at the Biology and Mars Experiment (BIOMEX), which is part of the ESA
mission EXPOSE-R2 on the International Space Station and was launched on 23 July 2014. In preparation for the
mission, several preflight tests (Experimental and Scientific Verification Tests, EVT and SVT) assessed the sample
preparation and hardware integration procedures as well as the resistance of the candidate organism toward the
abiotic stressors experienced under space and Mars conditions. Therefore, we quantified the post-exposure viability
with a live/dead staining technique utilizing FUN-1 and confocal laser scanning microscopy (CLSM). In addition,
we used scanning electron microscopy (SEM) to investigate putative patterns of morphological-anatomical damage
that lichens may suffer under the extreme exposure conditions. The present results demonstrate that Buellia frigida
is capable of surviving the conditions tested in EVT and SVT. The mycobiont showed lower average impairment of
its viability than the photobiont (viability rates of >83% and >69%, respectively), and the lichen thallus suffered no
significant damage in terms of thalline integrity and symbiotic contact. These results will become essential to
substantiate and validate the results prospectively obtained from the returning space mission. Moreover, they will
help assess the limits and limitations of terrestrial organisms under space and Mars conditions as well as characterize
the adaptive traits that confer lichen extremotolerance
Nanostructure of cobalt/copper multilayers
The nanostructure and local strain of [111] fcc Co/Cu multilayers are studied by means of nuclear magnetic resonance. The atomic topology of the interface can be deduced from the NMR spectrum and the local strains from the shift in the hyperfine fields. The results show that the Co/Cu interface is a mixed monolayer and that the Co layers, including the interface, have uniform strain inversely proportional to the Co thickness (within experimental error) with the proportionality constant depending on the Cu thickness