Current Issue : July - September Volume : 2012 Issue Number : 3 Articles : 4 Articles
A multiprism lens (MPL) is a refractive X-ray lens, and its chromatic properties can be employed in an energy filtering setup\r\nto obtain a narrow tunable X-ray spectrum. We present the first evaluation of such a filter for medical X-ray imaging. The\r\nexperimental setup yields a 6.6 gain of flux at 20 keV, and we demonstrate tunability by altering the energy spectrum to center also\r\naround 17 and 23 keV. All measurements are found to agree well with ray-tracing and a proposed geometrical model. Compared\r\nto a model mammography system with absorption filtering, the experimental MPL filter reduces dose 13ââ?¬â??25% for 3ââ?¬â??7 cm breasts\r\nif the spectrum is centered around the optimal energy. Additionally, the resolution is improved 2.5 times for a 5 cm breast. The\r\nscan time is increased 3 times but can be reduced with a slightly decreased energy filtering and resolution....
A Fresnel zone plate (FZP) with 35nm outermost zone width has been fabricated and tested in the hard X-ray region. The FZP\r\nwas made by electron beam lithography and reactive ion etching technique. The performance test of the FZP was carried out\r\nby measuring the focused beam profile for coherent hard X-ray beam at the beamline 20XU of SPring-8. The full width at half\r\nmaximum of the focused beam profile measured by knife-edge scan method is 34.9 �± 2.7 nm, that agrees well with the theoretical\r\nvalue of diffraction-limited resolution. Applications to scanning microscopy were also carried out....
Most of grazing incidence (reflective) X-ray imaging systems used in astronomy and in other (laboratory) applications are\r\nbased on the Wolter 1 (or modified) arrangement. But there were proposed also other designs and configurations, which are\r\nconsidered for future applications for both in laboratory and (finitely) in space. The Kirkpatrick-Baez (KB) lenses as well as\r\nvarious types of Lobster-Eye (LE) optics and MCP/Micropore optics serve as an example. Analogously toWolter lenses, the X-rays\r\nare mostly reflected twice in these systems to create focal images. The KB systems have already found wide usage in laboratory\r\nand synchrotron, both application are reviewed and discussed in detail in this paper. While this paper focuses on future possible\r\napplications of non-Wolter grazing incidence systems in space and astronomy, we also discuss in detail applications in other areas\r\nof science, where (in contrary to astronomy) some of these systems have demonstrated their advantages....
The mechanisms underlying pluripotency and differentiation in embryonic and reprogrammed stem cells are unclear. In this\r\nwork, we characterized the pluripotent state towards neural differentiated state through analysis of trace elements\r\ndistribution using the Synchrotron Radiation X-ray Fluorescence Spectroscopy. Naive and neural-stimulated embryoid\r\nbodies (EB) derived from embryonic and induced pluripotent stem (ES and iPS) cells were irradiated with a spatial resolution\r\nof 20 mm to make elemental maps and qualitative chemical analyses. Results show that these embryo-like aggregates\r\nexhibit self-organization at the atomic level. Metallic elements content rises and consistent elemental polarization pattern of\r\nP and S in both mouse and human pluripotent stem cells were observed, indicating that neural differentiation and\r\nelemental polarization are strongly correlated....
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