52 research outputs found
Current-induced magnetic superstructures in exchange-spring devices
We investigate the potential to use a magneto-thermo-electric instability
that may be induced in a mesoscopic magnetic multi-layer (F/f/F) to create and
control magnetic superstructures. In the studied multilayer two strongly
ferromagnetic layers (F) are coupled through a weakly ferromagnetic spacer (f)
by an "exchange spring" with a temperature dependent "spring constant" that can
be varied by Joule heating caused by an electrical dc current. We show that in
the current-in-plane (CIP) configuration a distribution of the magnetization,
which is homogeneous in the direction of the current flow, is unstable in the
presence of an external magnetic field if the length L of the sample in this
direction exceeds some critical value Lc ~ 10 \mu m. This spatial instability
results in the spontaneous formation of a moving domain of magnetization
directions, the length of which can be controlled by the bias voltage in the
limit L >> Lc. Furthermore, we show that in such a situation the
current-voltage characteristics has a plateau with hysteresis loops at its ends
and demonstrate that if biased in the plateau region the studied device
functions as an exponentially precise current stabilizer.Comment: 8 pages, 6 figure
Injection of photoelectrons into dense argon gas
The injection of photoelectrons in a gaseous or liquid sample is a widespread
technique to produce a cold plasma in a weakly--ionized system in order to
study the transport properties of electrons in a dense gas or liquid. We report
here the experimental results of photoelectron injection into dense argon gas
at the temperatureT=142.6 K as a function of the externally applied electric
field and gas density. We show that the experimental data can be interpreted in
terms of the so called Young-Bradbury model only if multiple scattering effects
due to the dense environment are taken into account when computing the
scattering properties and the energetics of the electrons.Comment: 18 pages, 10 figures, figure nr. 10 has been redrawn, to be submitted
to Plasma Sources Science and Technolog
Identification of sortase A (SrtA) substrates in Streptococcus uberis: evidence for an additional hexapeptide (LPXXXD) sorting motif
Sortase (a transamidase) has been shown to be responsible for the covalent attachment of proteins to the bacterial cell wall. Anchoring is effected on secreted proteins containing a specific cell wall motif toward their C-terminus; that for sortase A (SrtA) in Gram-positive bacteria often incorporates the sequence LPXTG. Such surface proteins are often characterized as virulence determinants and play important roles during the establishment and persistence of infection. Intramammary infection with Streptococcus uberis is a common cause of bovine mastitis, which impacts on animal health and welfare and the economics of milk production. Comparison of stringently produced cell wall fractions from S. uberis and an isogenic mutant strain lacking SrtA permitted identification of 9 proteins likely to be covalently anchored at the cell surface. Analysis of these sequences implied the presence of two anchoring motifs for S. uberis, the classical LPXTG motif and an additional LPXXXD motif
Mobility of non thermal electrons and ions in very high density and purified nitrogen corona discharge
WOS:000471052300021International audienceThe mobility of nonthermal electrons and ions have been determined in very high and purified nitrogen corona discharge. Corona discharge was generated by plasma generator system with point-to-plane electrodes geometry configuration. Charateristic I-V has been done by using stabilized DC high voltage generator high up to 20 kV. Graph current of saturation corona unipolar for variation voltage and the distance between electrodes is curved with the semi-parabolic equation. We used I-V characteristic to determine charge patricles mobilities. In this research high purified and slighly purified nitrogen gas. For negative corona, we found that the mobility of charged particles is greater than negative ions and smaller than thermal electron mobility. Particles engaging and moving in the corona with high purification the gas are nonthermal electrons, positive ions for positive corona. From the current-voltage characteristic, we can conclude that the regime of our discharge in very pure gases (N2) corresponds to the current regime limited by space charge. By analogy with what has been observed in a "discharge tube" this regime is similar to an abnormal glow discharge regime. We have seen previously that the variation with the density of the ionic mobility is in good agreement with the direct measurements by the time of flight metho
Mobility of non thermal electrons and ions in very high density and purified nitrogen corona discharge
WOS:00047105230002
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