DEIMOS: a beamline dedicated to dichroism measurements in the 350-2500 eV energy range.

The DEIMOS (Dichroism Experimental Installation for Magneto-Optical Spectroscopy) beamline was part of the second phase of the beamline development at French Synchrotron SOLEIL (Source Optimisée de Lumière à Energie Intermédiaire du LURE) and opened to users in March 2011. It delivers polarized soft x-rays to perform x-ray absorption spectroscopy, x-ray magnetic circular dichroism, and x-ray linear dichroism in the energy range 350-2500 eV. The beamline has been optimized for stability and reproducibility in terms of photon flux and photon energy. The main end-station consists in a cryo-magnet with 2 split coils providing a 7 T magnetic field along the beam or 2 T perpendicular to the beam with a controllable temperature on the sample from 370 K down to 1.5 K.

Carbon contamination of soft X-ray beamlines: dramatic anti-reflection coating effects observed in the 1 keV photon energy region.

Carbon contamination is a general problem of under-vacuum optics submitted to high fluence. In soft X-ray beamlines carbon deposit on optics is known to absorb and scatter radiation close to the C K-edge (280 eV), forbidding effective measurements in this spectral region. Here the observation of strong reflectivity losses is reported related to carbon deposition at much higher energies around 1000 eV, where carbon absorptivity is small. It is shown that the observed effect can be modelled as a destructive interference from a homogeneous carbon thin film.

Optimization strategies for XUV monochromators.

The techniques of monochromator optimization are reviewed, and it is shown that until recently only a few of the available parameters were used at the same time. Efficient optimization can be performed numerically. The computation method developed at LURE is explained and an example is given. Extension and development of the method are outlined.

High-flux and high-resolution spectroscopic facility in the VUV region at Super-ACO.

A new spectroscopic facility, consisting of a planar/helical undulator and a 6.65 m off-plane Eagle monochromator, has been designed. It can supply high-flux and high-resolution photons with 'exotic' polarization in the 5-40 eV energy range. The astigmatism can be compromised by horizontally focusing the incident radiation on the grating. The rotation of a post-focusing toroidal mirror compensates for the deviation of the exit beam caused by the grating translation. The whole system will be installed at beamline SU5 of SUPER-ACO (0.8 GeV) at the beginning of 1998. With a 4300 grooves mm(-1) grating, a resolving power of around 10(5) is expected at 20 eV.

Does halothane interfere with the release, action, or stability of endothelium-derived relaxing factor/nitric oxide?

BACKGROUND: Halothane attenuates endothelium-dependent relaxation. To differentiate halothane's effect on endothelium-derived relaxing factor/nitric oxide (EDRF/NO) production from its effect on nitric oxide action on vascular smooth muscle, halothane's effect on endothelium-dependent relaxation was studied in a bioassay system. METHODS: Indomethacin-treated, bovine aortic endothelial cells (BAEC) grown on microcarrier beads, continuously perfused by oxygenated and carbonated (95% O2, 5% CO2) Krebs-Ringer solution served as nitric oxide donors while an isolated denuded rabbit aortic ring directly superfused by the effluent of the BAEC and precontracted with phenylephrine was used to detect EDRF/NO release. The effect of basal and bradykinin-stimulated EDRF release on the tension of the vascular ring was measured. In the bioassay, it was possible to treat either the vascular denuded ring alone or the vascular ring plus the BAEC with halothane by adding it to the perfusate either upstream or downstream from the BAEC. Halothane (final concentration 2.2%) was added to the perfusate at these two positions, and its effect on the relaxation induced by EDRF/NO was determined. In some experiments, the preparations were treated with hemoglobin or L-monomethyl-L-arginine to attenuate the relaxation induced by the EDRF/NO pathway. Finally, halothane's effect on vascular relaxation induced by an increasing concentration of sodium nitroprusside was measured. Halothane's concentration in the perfusate was determined by gas chromatography using electron capture for anesthetic measurement. RESULTS: EDRF/NO released by the BAEC was responsible for the relaxation of the vascular ring. Halothane added to the perfusate potentiated the tension induced by phenylephrine (7.1 +/- 1.89%) and attenuated the relaxation induced by the release of EDRF/NO. This effect was reversible after discontinuation of halothane. Halothane's effect was present even when the anesthetic was added to the perfusate downstream to the perfusion of the endothelial cells. Halothane had no effect on the vascular relaxation induced by sodium nitroprusside. CONCLUSIONS: The authors' data demonstrate that halothane does not interfere with endothelial cell release of EDRF/NO and its smooth muscle cell relaxation but seems to modify either EDRF/NO half-life or its activated redox form.