Biomedical subjects

F Polack

Publications and source records attributed to F Polack.

5 recordsLinked to original sources

PubMed2000

SB7: the new bending-magnet double-headed dragon beamline at SuperACO.

A new beamline is now operational at LURE on bending-magnet 7 of the SuperACO storage ring in Orsay. The monochromator is of the ;dragon' type, designed to work in the energy range 150-1500 eV, and is equipped with a double vertical focusing mirror in order to allow for fast switching of light polarization. In this paper the results of photoion-yield experiments performed on N(2), Ar and Ne gases are presented. The observed resonance structures enable us to determine the available energy resolution: a resolving power higher than 8500 is obtained at the Ar 2p, N 1s and Ne K-edges when using all the optical elements at full aperture. The total flux as a function of the measured photon energy resolution and the characterization of the double-head behaviour in delivering circularly polarized light are reported.

Journal Article↗

PubMed1998

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.

Journal Article↗

PubMed1998

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.

Journal Article↗

PubMed1987

The photoelectron x-ray microscope, a possible tool for analytical soft x-ray microscopy.

In the soft x-ray region, different techniques have been recently developed which can give images of biological objects at an intermediate resolution between optical and electron microscopes. At these wavelengths, very little sample preparation is required because the image contrast is directly dependent upon the chemical composition of the sample itself and on the x-ray wavelength. X-ray microscopy can be extended to absorption microanalysis with a similar resolution, provided that the basic microscope can work through a large range of wavelengths. The photoelectron x-ray microscope that we are developing at LURE satisfies this condition. Its principle is to make a contact x-ray image of the object on a plane photocathode and then, to magnify the secondary electron image, into which it is converted, by means of an emission electron microscope. In the present state of the art, the expectable detection limit, for element maps of 0.1 micron resolution, would be near 1% in concentration.

Electron Probe Microanalysis↗

PubMed1976

Immune host response to corneal grafts sensitized to herpes simplex virus.

Experiments were performed to study the fate of corneal grafts sensitized to herpes antigens when grafted to HSV-sensitized hosts. Nonsensitized grafts in systemically sensitized hosts remained clear, whereas all locally sensitized grafts in systemically sensitized hosts became opaque within ten days. The stroma showed severe lymphocytic and plasma cell infiltration and neovascularization. One-half of the corneas from systemically sensitized hosts grafted to eyes previously infected opacified in an accelerated manner. Round cells were found in the stroma and endothelium. The histological reaction in both groups was similar to that found in the immune graft reaction even though the clinical picture was not typical (peripheral and progressive edema with a rejection line). The accelerated reaction was probably related to the presence of virus antigens in graft stroma and subepithelial areas of the graft. The significance of HSV-sensitized donor tissue grafted onto HSV-sensitized hosts is discussed because of its possible implication in tissue transplantation.

Animals↗