Search

Some ascidians (sea squirts) accumulate the transitional metal vanadium in their blood cells at concentrations of up to 350 mM, about 10(7) times its concentration found in seawater. There are approximately 10 different types of blood cell in ascidians. The identity of the true vanadium-containing blood cell (vanadocyte) is controversial and little is known about the subcellular distribution of vanadium. A scanning x-ray microscope installed at the ID21 beamline of the European Synchroton Radiation Facility to visualize vanadium in ascidian blood cells. Without fixation, freezing or staining realized the visualization of vanadium localized in living signet ring cells and vacuolated amoebocytes of two vanadium-rich ascidian species, Phallusia mammillata and Ascidia sydneiensis samea. A combination of transmission and fluorescence images of signet ring cells suggested that in both species the vacuoles contain vanadium.

Oil paintings are complex hybrid materials, made of organic binders associated with inorganic minerals, susceptible to evolving over centuries. In particular, interactions of oil with lead compounds may give rise to the formation of lead soap aggregates, so-called protrusions. This phenomenon is studied here via X-ray and FTIR micro-analysis of an ancient painting dated from 1610. In complement, the synthesis of modern preparations, reconstructed from ancient recipes was assessed. Molecular and atomic images are obtained by combining synchrotron-based FTIR and X-ray fluorescence microscopies. Protrusions are identified in both ancient and modern samples, more particularly, in the ground layer of the paintings, below the colored layer. These observations imply that lead oxide, introduced as a siccative and not as a pigment, may be the element mainly responsible for the protrusions formation, and that this degradation may appear very rapidly on paintings. [ABSTRACT FROM AUTHOR]

Describes the features of the X-ray microscopy and micro-spectroscopy equipment located at the European Synchrotron Radiation Facility in France. Fields of application driven by unique attributes of X-ray microscopy; High-spatial resolution focus; Research projects being performed in the microscopy facility.

In this work, an imaging tool to investigate optical inhomogeneities with site and chemical sensitivities has been integrated in a hard x-ray microprobe. Freestanding GaN and epitaxially grown GaN:Mn on α-Al2O3 are used to exploit the unprecedented scanning x-ray excited luminescence technique. Optical images of the radiative recombination channels are reported for several impurities and defect centers in sapphire and GaN compounds. Within the experimental accuracy, a visible nonuniformity characterizes the Mn centers in good correlation with former x-ray fluorescence map. Expanding the microprobe versatility, x-ray absorption spectroscopy in both photon collection modes (x-ray excited luminescence and x-ray fluorescence) is finally presented from a freestanding GaN layer. [ABSTRACT FROM AUTHOR]

Information on the Seventh X-ray microscopy (XRM) conference hosted by the European Synchrotron Radiation Facility (ESRF) from July 28 to August 2, 2002 held at the ATRIA World Trade Centre in Grenoble, France is presented. Topics explored include the developments on X-ray microscopy techniques and accomplishments in biology, earth sciences, and materials science. The conference featured 239 participants such as professor A. Michette, Michael Feser, and professor G. Schmahl.