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X-ray Microscopy (x-ray + microscopy)
Kinds of X-ray Microscopy Selected AbstractsApplication of Synchrotron Radiation Techniques for Model Validation of Advanced Structural Materials,ADVANCED ENGINEERING MATERIALS, Issue 6 2009Annick Froideval Abstract Synchrotron radiation techniques represent powerful tools to characterize materials down to the nanometer level. This paper presents a survey of the state-of-the-art synchrotron-based techniques which are particularly well-suited for investigating materials properties. Complementary X-ray absorption techniques such as extended X-ray absorption fine structure (EXAFS), X-ray magnetic circular dichroism (XMCD), photoemission electron microscopy (PEEM) are used to address the individual local atomic structure and magnetic moments in Fe,Cr model systems. The formation of atomic clusters/precipitates in such systems is also investigated by means of scanning transmission X-ray microscopy (STXM). Such advanced analytical techniques can not only offer valuable structural and magnetic information on such systems, they can also serve for validating computational calculations performed at different time and length scales which can help improve materials lifetime predictions. [source] Three-dimensional reconstruction of the odontophoral cartilages of Caenogastropoda (Mollusca: Gastropoda) using micro-CT: Morphology and phylogenetic significanceJOURNAL OF MORPHOLOGY, Issue 5 2009Rosemary E. Golding Abstract Odontophoral cartilages are located in the molluscan buccal mass and support the movement of the radula during feeding. The structural diversity of odontophoral cartilages is currently known only from limited taxa, but this information is important for interpreting phylogeny and for understanding the biomechanical operation of the buccal mass. Caenogastropods exhibit a wide variety of feeding strategies, but there is little comparative information on cartilage morphology within this group. The morphology of caenogastropod odontophoral cartilages is currently known only from dissection and histology, although preliminary results suggest that they may be structurally diverse. A comparative morphological survey of 18 caenogastropods and three noncaenogastropods has been conducted, sampling most major caenogastropod superfamilies. Three-dimensional models of the odontophoral cartilages were generated using X-ray microscopy (micro-CT) and reconstruction by image segmentation. Considerable morphological diversity of the odontophoral cartilages was found within Caenogastropoda, including the presence of thin cartilaginous appendages, asymmetrically overlapping cartilages, and reflexed cartilage margins. Many basal caenogastropod taxa possess previously unidentified cartilaginous support structures below the radula (subradular cartilages), which may be homologous to the dorsal cartilages of other gastropods. As subradular cartilages were absent in carnivorous caenogastropods, adaptation to trophic specialization is likely. However, incongruence with specific feeding strategies or body size suggests that the morphology of odontophoral cartilages is constrained by phylogeny, representing a new source of morphological characters to improve the phylogenetic resolution of this group. J. Morphol. 2009. © 2008 Wiley-Liss, Inc. [source] X-ray spectromicroscopy in soil and environmental sciencesJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2010J. Thieme X-ray microscopy is capable of imaging particles in the nanometer size range directly with sub-micrometer spatial resolution and can be combined with high spectral resolution for spectromicroscopy studies. Two types of microscopes are common in X-ray microscopy: the transmission X-ray microscope and the scanning transmission X-ray microscope; their set-ups are explained in this paper. While the former takes high-resolution images from an object with exposure times of seconds or faster, the latter is very well suited as an analytical instrument for spectromicroscopy. The morphology of clusters or particles from soil and sediment samples has been visualized using a transmission X-ray microscope. Images are shown from a cryo-tomography experiment based on X-ray microscopy images to obtain information about the three-dimensional structure of clusters of humic substances. The analysis of a stack of images taken with a scanning transmission X-ray microscope to combine morphology and chemistry within a soil sample is shown. X-ray fluorescence is a method ideally applicable to the study of elemental distributions and binding states of elements even on a trace level using X-ray energies above 1,keV. [source] Humic acid metal cation interaction studied by spectromicroscopy techniques in combination with quantum chemical calculationsJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2010M. Plaschke Humic acids (HA) have a high binding capacity towards traces of toxic metal cations, thus affecting their transport in aquatic systems. Eu(III),HA aggregates are studied by synchrotron-based scanning transmission X-ray microscopy (STXM) at the carbon K -edge and laser scanning luminescence microscopy (LSLM) at the 5D0,7F1,2 fluorescence emission lines. Both methods provide the necessary spatial resolution in the sub-micrometre range to resolve characteristic aggregate morphologies: optically dense zones embedded in a matrix of less dense material in STXM images correspond to areas with increased Eu(III) luminescence yield in the LSLM micrographs. In the C 1s -NEXAFS of metal-loaded polyacrylic acid (PAA), used as a HA model compound, a distinct complexation effect is identified. This effect is similar to trends observed in the dense fraction of HA/metal cation aggregates. The strongest complexation effect is observed for the Zr(IV),HA/PAA system. This effect is confirmed by quantum chemical calculations performed at the ab initio level for model complexes with different metal centres and complex geometries. Without the high spatial resolution of STXM and LSLM and without the combination of molecular modelling with experimental results, the different zones indicating a `pseudo'-phase separation into strong complexing domains and weaker complexing domains of HA would never have been identified. This type of strategy can be used to study metal interaction with other organic material. [source] A new bend-magnet beamline for scanning transmission X-ray microscopy at the Advanced Light SourceJOURNAL OF SYNCHROTRON RADIATION, Issue 4 2002Harald Ade The high brightness of the bend magnets at the Advanced Light Source has been exploited to illuminate a scanning transmission X-ray microscope (STXM). This is the first diffraction-limited scanning X-ray microscope to operate with a useful count rate on a synchrotron bend-magnet source. A simple dedicated beamline has been built covering the range of photon energy from 250,eV to 600,eV. The beamline is always available and needs little adjustment. Use of this facility is much easier than that of installations that share undulator beams. This facility provides radiation for C 1s, N 1s and O 1s near-edge X-ray absorption spectromicroscopy with STXM count rates in excess of 1,MHz and with spectral resolution typically 1:2000, limited to about 1:5000. [source] Investigation of phase contrast hard X-ray microscopy using planar sets of refractive crossed linear parabolic lenses made from SU-8 polymerPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2007E. Reznikova Abstract Planar X-ray refractive lenses with parabolic surface profile, and in crossed geometry to provide 2D focusing, are fabricated from SU-8 polymer using the LIGA process and deep X-ray lithography technology. A transmission X-ray microscope (TXM) using a condenser and an objective lens based on this type of X-ray optics was set up at the ESRF beamline BM 5, for photon energies of 17.1 and 18 keV. Test structures made of gold and SU-8, with different thicknesses, were imaged with this TXM using in-line phase-contrast, with X-ray magnification factors of 13,20, spatial resolution between 0.2 and 0.3 µm and exposure times around 1 s. The advantages of a TXM based on refractive SU-8 planar crossed condenser and objective and the optimisation of the optical scheme and of the condenser focusing profile are discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Shuttling Gold Nanoparticles into Tumoral Cells with an Amphipathic Proline-Rich PeptideCHEMBIOCHEM, Issue 6 2009Sílvia Pujals Abstract Golden bullets: The amphipathic proline-rich cell-penetrating peptide sweet arrow peptide (SAP) is able to transport 12 nm gold nanoparticles efficiently into HeLa cells, as observed by three microscopy techniques: transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM) and transmission X-ray microscopy (TXM). Multiconjugation to such nanoparticles may provide a convenient method for unifying the key drug properties of high activity, capacity to home onto targets and delivery to therapeutic places of action. Cell-penetrating peptides (CPPs) are a potential tool for intracellular delivery of different kinds of cargoes. Because of their growing use in nanobiomedicine, both for diagnostics and for treatment, metal nanoparticles are an interesting cargo for CPPs. Here, gold nanoparticles (AuNps) and the amphipathic proline-rich peptide SAP have been used. Conjugation of the peptide onto the AuNps was achieved by addition of a cysteine to the SAP sequence for thiol chemisorption on gold, and the attachment was confirmed by visible spectroscopy, dynamic light scattering (DLS), ,-potential (ZP), stability towards ionic strength (as high as 1,M NaCl), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HR-TEM) coupled to electron energy loss spectroscopy (EELS). AuNp-C-SAP internalization in HeLa cells was observed by three different microscopy techniques,TEM, confocal laser scanning microscopy (CLSM) and transmission X-ray microscopy (TXM),and all of them have confirmed the effective intracellular delivery of AuNps by SAP. [source] | ||||||||||