1,014 research outputs found
Influence of magnetic field and ferromagnetic film thickness on domain pattern transfer in multiferroic heterostructures
Domains in BaTiO induces a regular modulation of uniaxial magnetic
anisotropy in CoFeB via an inverse magnetostriction effect. As a result, the
domain structures of the CoFeB wedge film and BaTiO substrate correlate
fully and straight ferroelectric domain boundaries in BaTiO pin magnetic
domain walls in CoFeB. We use x-ray photoemission electron microscopy and
magneto-optical Kerr effect microscopy to characterize the spin structure of
the pinned domain walls. In a rotating magnetic field, abrupt and reversible
transitions between two domain wall types occur, namely, narrow walls where the
magnetization vectors align head-to-tail and much broader walls with
alternating head-to-head and tail-to-tail magnetization configurations. We
characterize variations of the domain wall spin structure as a function of
magnetic field strength and CoFeB film thickness and compare the experimental
results with micromagnetic simulations.Comment: 5 pages, 5 figure
Field Tuning of Ferromagnetic Domain Walls on Elastically Coupled Ferroelectric Domain Boundaries
We report on the evolution of ferromagnetic domain walls during magnetization
reversal in elastically coupled ferromagnetic-ferroelectric heterostructures.
Using optical polarization microscopy and micromagnetic simulations, we
demonstrate that the spin rotation and width of ferromagnetic domain walls can
be accurately controlled by the strength of the applied magnetic field if the
ferromagnetic walls are pinned onto 90 degrees ferroelectric domain boundaries.
Moreover, reversible switching between magnetically charged and uncharged
domain walls is initiated by magnetic field rotation. Switching between both
wall types reverses the wall chirality and abruptly changes the width of the
ferromagnetic domain walls by up to 1000%.Comment: 5 pages, 5 figure
Radiology in the lead:towards radiological profiling for precision medicine in glioblastoma patients? Editorial comment on Glioblastoma patients with a moderate vascular profile benefit the most from MGMT methylation
Extension of Yeast Chronological Lifespan by Methylamine
Background: Chronological aging of yeast cells is commonly used as a model for aging of human post-mitotic cells. The yeast Saccharomyces cerevisiae grown on glucose in the presence of ammonium sulphate is mainly used in yeast aging research. We have analyzed chronological aging of the yeast Hansenula polymorpha grown at conditions that require primary peroxisome metabolism for growth.
Methodology/Principal Findings: The chronological lifespan of H. polymorpha is strongly enhanced when cells are grown on methanol or ethanol, metabolized by peroxisome enzymes, relative to growth on glucose that does not require peroxisomes. The short lifespan of H. polymorpha on glucose is mainly due to medium acidification, whereas most likely ROS do not play an important role. Growth of cells on methanol/methylamine instead of methanol/ammonium sulphate resulted in further lifespan enhancement. This was unrelated to medium acidification. We show that oxidation of methylamine by peroxisomal amine oxidase at carbon starvation conditions is responsible for lifespan extension. The methylamine oxidation product formaldehyde is further oxidized resulting in NADH generation, which contributes to increased ATP generation and reduction of ROS levels in the stationary phase.
Conclusion/Significance: We conclude that primary peroxisome metabolism enhanced chronological lifespan of H. polymorpha. Moreover, the possibility to generate NADH at carbon starvation conditions by an organic nitrogen source supports further extension of the lifespan of the cell. Consequently, the interpretation of CLS analyses in yeast should include possible effects on the energy status of the cell.
d0 Ferromagnetic Interface Between Non-magnetic Perovskites
We use computational and experimental methods to study d0 ferromagnetism at a
charge- imbalanced interface between two perovskites. In SrTiO3/KTaO3
superlattice calculations, the charge imbalance introduces holes in the SrTiO3
layer, inducing a d0 ferromagnetic half-metallic 2D electron gas at the
interface oxygen 2p orbitals. The charge imbalance overrides doping by
vacancies at realistic concentrations. Varying the constituent materials shows
ferromagnetism to be a gen- eral property of hole-type d0 perovskite
interfaces. Atomically sharp epitaxial d0 SrTiO3/KTaO3, SrTiO3 /KNbO3 and
SrTiO3 /NaNbO3 interfaces are found to exhibit ferromagnetic hysteresis at room
temperature. We suggest the behavior is due to high density of states and
exchange coupling at the oxygen t1g band in comparison with the more studied d
band t2g symmetry electron gas.Comment: 5 pages, 5 figure
Carbonic anhydrases CA1 and CA4 function in atmospheric CO2-modulated disease resistance
Main conclusion Carbonic anhydrases CA1 and CA4 attenuate plant immunity and can contribute to altered disease resistance levels in response to changing atmospheric CO2 conditions. Abstract β-Carbonic anhydrases (CAs) play an important role in CO2 metabolism and plant development, but have also been implicated in plant immunity. Here we show that the bacterial pathogen Pseudomonas syringae and application of the microbe-associated molecular pattern (MAMP) flg22 repress CA1 and CA4 gene expression in Arabidopsis thaliana. Using the CA double-mutant ca1ca4, we provide evidence that CA1 and CA4 play an attenuating role in pathogen- and flg22-triggered immune responses. In line with this, ca1ca4 plants exhibited enhanced resistance against P. syringae, which was accompanied by an increased expression of the defense-related genes FRK1 and ICS1. Under low atmospheric CO2 conditions (150 ppm), when CA activity is typically low, the levels of CA1 transcription and resistance to P. syringae in wild-type Col-0 were similar to those observed in ca1ca4. However, under ambient (400 ppm) and elevated (800 ppm) atmospheric CO2 conditions, CA1 transcription was enhanced and resistance to P. syringae reduced. Together, these results suggest that CA1 and CA4 attenuate plant immunity and that differential CA gene expression in response to changing atmospheric CO2 conditions contribute to altered disease resistance levels
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