Simulations of X-ray diffraction of shock-compressed single-crystal tantalum with synchrotron undulator sources

Energy Technology Data Exchange (ETDEWEB)

Tang, M. X.; Zhang, Y. Y.; E, J. C.; Luo, S. N.

2018-04-24

Polychromatic synchrotron undulator X-ray sources are useful for ultrafast single-crystal diffraction under shock compression. Here, simulations of X-ray diffraction of shock-compressed single-crystal tantalum with realistic undulator sources are reported, based on large-scale molecular dynamics simulations. Purely elastic deformation, elastic–plastic two-wave structure, and severe plastic deformation under different impact velocities are explored, as well as an edge release case. Transmission-mode diffraction simulations consider crystallographic orientation, loading direction, incident beam direction, X-ray spectrum bandwidth and realistic detector size. Diffraction patterns and reciprocal space nodes are obtained from atomic configurations for different loading (elastic and plastic) and detection conditions, and interpretation of the diffraction patterns is discussed.

Optical Observations of X-ray Bright, Optically Normal Galaxies

Science.gov (United States)

Sadun, Alberto C.; Aryan, N. S.; Ghosh, K. K.

2007-05-01

X-ray bright, optically normal galaxies (XBONGs) are galaxies that seem to have normal spectra and morphology, but are relatively bright x-ray sources. The large ratio of the x-ray to optical emission suggests that some activity, similar to that of active galactic nuclei (AGN), is occurring. Since the galaxies do not show any obvious sign of nuclear activity in their optical spectra, one possible explanation is that these galaxies do not have an optically thick accretion disk at small radii, as previously assumed. Previous data for NGC 7626 classifies it as an XBONG, and so we are studying optical features of this galaxy in order to determine better its features. After confirming an x-ray jet, we are now comparing this to optical features that we have found, including warped dust lanes and a possible optical jet.

Non-destructive analysis of micro texture and grain boundary character from X-ray diffraction contrast tomography

DEFF Research Database (Denmark)

King, A.; Herbig, M.; Ludwig, W.

2010-01-01

Recent advances in synchrotron based X-ray imaging and diffraction techniques offer interesting new possibilities for mapping 3D grain shapes and crystallographic orientations in different classes of polycrystalline materials. X-ray diffraction contrast tomography (DCT) is a monochromatic beam...... imaging technique combining the principles of X-ray micro-tomography and three-dimensional X-ray diffraction microscopy (3DXRD). DCT provides simultaneous access to 3D grain shape, crystallographic orientation and attenuation coefficient distribution at the micrometer length scale. The microtexture...

A laboratory-based hard x-ray monochromator for high-resolution x-ray emission spectroscopy and x-ray absorption near edge structure measurements

Energy Technology Data Exchange (ETDEWEB)

Seidler, G. T., E-mail: seidler@uw.edu; Mortensen, D. R.; Remesnik, A. J.; Pacold, J. I.; Ball, N. A.; Barry, N.; Styczinski, M.; Hoidn, O. R. [Physics Department, University of Washington, Seattle, Washington 98195-1560 (United States)

2014-11-15

We report the development of a laboratory-based Rowland-circle monochromator that incorporates a low power x-ray (bremsstrahlung) tube source, a spherically bent crystal analyzer, and an energy-resolving solid-state detector. This relatively inexpensive, introductory level instrument achieves 1-eV energy resolution for photon energies of ∼5 keV to ∼10 keV while also demonstrating a net efficiency previously seen only in laboratory monochromators having much coarser energy resolution. Despite the use of only a compact, air-cooled 10 W x-ray tube, we find count rates for nonresonant x-ray emission spectroscopy comparable to those achieved at monochromatized spectroscopy beamlines at synchrotron light sources. For x-ray absorption near edge structure, the monochromatized flux is small (due to the use of a low-powered x-ray generator) but still useful for routine transmission-mode studies of concentrated samples. These results indicate that upgrading to a standard commercial high-power line-focused x-ray tube or rotating anode x-ray generator would result in monochromatized fluxes of order 10{sup 6}–10{sup 7} photons/s with no loss in energy resolution. This work establishes core technical capabilities for a rejuvenation of laboratory-based hard x-ray spectroscopies that could have special relevance for contemporary research on catalytic or electrical energy storage systems using transition-metal, lanthanide, or noble-metal active species.

Standard practice for X-Ray determination of retained austenite in steel with near random crystallographic orientation

CERN Document Server

American Society for Testing and Materials. Philadelphia

2003-01-01

1.1 This practice covers the determination of retained austenite phase in steel using integrated intensities (area under peak above background) of X-ray diffraction peaks using chromium Kα or molybdenum Kα X-radiation. 1.2 The method applies to carbon and alloy steels with near random crystallographic orientations of both ferrite and austenite phases. 1.3 This practice is valid for retained austenite contents from 1 % by volume and above. 1.4 If possible, X-ray diffraction peak interference from other crystalline phases such as carbides should be eliminated from the ferrite and austenite peak intensities. 1.5 Substantial alloy contents in steel cause some change in peak intensities which have not been considered in this method. Application of this method to steels with total alloy contents exceeding 15 weight % should be done with care. If necessary, the users can calculate the theoretical correction factors to account for changes in volume of the unit cells for austenite and ferrite resulting from vari...

Pixelated transmission-mode diamond X-ray detector.

Science.gov (United States)

Zhou, Tianyi; Ding, Wenxiang; Gaowei, Mengjia; De Geronimo, Gianluigi; Bohon, Jen; Smedley, John; Muller, Erik

2015-11-01

Fabrication and testing of a prototype transmission-mode pixelated diamond X-ray detector (pitch size 60-100 µm), designed to simultaneously measure the flux, position and morphology of an X-ray beam in real time, are described. The pixel density is achieved by lithographically patterning vertical stripes on the front and horizontal stripes on the back of an electronic-grade chemical vapor deposition single-crystal diamond. The bias is rotated through the back horizontal stripes and the current is read out on the front vertical stripes at a rate of ∼ 1 kHz, which leads to an image sampling rate of ∼ 30 Hz. This novel signal readout scheme was tested at beamline X28C at the National Synchrotron Light Source (white beam, 5-15 keV) and at beamline G3 at the Cornell High Energy Synchrotron Source (monochromatic beam, 11.3 keV) with incident beam flux ranges from 1.8 × 10(-2) to 90 W mm(-2). Test results show that the novel detector provides precise beam position (positional noise within 1%) and morphology information (error within 2%), with an additional software-controlled single channel mode providing accurate flux measurement (fluctuation within 1%).

Crystallization and preliminary X-ray crystallographic studies of VibE, a vibriobactin-specific 2,3-dihydroxybenzoate-AMP ligase from Vibrio cholerae

International Nuclear Information System (INIS)

Liu, Xiuhua; Wang, Zhi; Zhu, Deyu; Wei, Tiandi; Gu, Lichuan; Xu, Sujuan

2011-01-01

This article reports the molecular cloning, protein expression and purification, crystallization and preliminary X-ray crystallographic analysis of the vibriobactin synthetase VibE from V. cholerae. Vibriobactin synthetases (VibABCDEFH) catalyze the biosynthesis of vibriobactin in the pathogenic bacterium Vibrio cholerae. VibE, a vibriobactin-specific 2,3-dihydroxybenzoate-AMP ligase, plays a critical role in the transfer of 2,3-dihydroxybenzoate to the aryl carrier protein domain of holo VibB. Here, the cloning, protein expression and purification, crystallization and preliminary X-ray crystallographic analysis of VibE from V. cholerae are reported. The VibE crystal diffracted to 2.3 Å resolution. The crystal belonged to space group P2 1 , with unit-cell parameters a = 56.471, b = 45.927, c = 77.014 Å, β = 95.895°. There is one protein molecule in the asymmetric unit, with a corresponding Matthews coefficient of 1.63 Å 3 Da −1 and solvent content of 24.41%

JAX: a micro-computer based X-ray diffractometer controller

International Nuclear Information System (INIS)

Naval, P.C. Jr.

1987-05-01

This paper describes a micro-computer based X-ray diffractometer controller and explores its possibilities in simplifying acquisition and analysis of X-ray powder diffraction data. The interrupt-driven controller can operate in both present time and present count data acquisition modes and allows a data analysis program to execute concurrently with data collection. (Auth.). 16 figs.; 2 tabs

Thermo mechanical design of normal-conducting deflecting cavities at the Advanced Photon Source for short x-ray pulse generation.

Energy Technology Data Exchange (ETDEWEB)

Brajuskovic, B.; Collins, J.; Den Hartog, P.; Morrison, L.; Waldschmidt, G.

2008-01-01

A normal-conducting deflecting cavity is being designed at the Advanced Photon Source (APS) as a part of the short x-ray pulse project intended to provide users with approximately 2 picosecond x-rays. The system will use two pairs of 3-cell cavities in sectors 6ID and 7ID for the generation of the x-ray pulse in the 7ID beamline. The 3-cell cavities are designed to provide the desired beam deflection while absorbing in excess of 4 kW of power from a pulsed rf system and up to 2.6 kW in the damper system of high-order mode (HOM) and low-order mode (LOM) waveguides. Since the cavity frequency is very sensitive to thermal expansion, the cooling water system is designed so that it is able to control cavity temperature to within 0.1 C. This paper describes the optimization of the thermomechanical design of the cavity based on calculation of thermal stresses and displacement caused by the generated heat loads, and presents the design of a cooling water system required for the proper operation of the cavities.

Advanced Nanoscale Characterization of Cement Based Materials Using X-Ray Synchrotron Radiation: A Review

KAUST Repository

Chae, Sejung R.

2013-05-22

We report various synchrotron radiation laboratory based techniques used to characterize cement based materials in nanometer scale. High resolution X-ray transmission imaging combined with a rotational axis allows for rendering of samples in three dimensions revealing volumetric details. Scanning transmission X-ray microscope combines high spatial resolution imaging with high spectral resolution of the incident beam to reveal X-ray absorption near edge structure variations in the material nanostructure. Microdiffraction scans the surface of a sample to map its high order reflection or crystallographic variations with a micron-sized incident beam. High pressure X-ray diffraction measures compressibility of pure phase materials. Unique results of studies using the above tools are discussed-a study of pores, connectivity, and morphology of a 2,000 year old concrete using nanotomography; detection of localized and varying silicate chain depolymerization in Al-substituted tobermorite, and quantification of monosulfate distribution in tricalcium aluminate hydration using scanning transmission X-ray microscopy; detection and mapping of hydration products in high volume fly ash paste using microdiffraction; and determination of mechanical properties of various AFm phases using high pressure X-ray diffraction. © 2013 The Author(s).

X-ray crystallography

Science.gov (United States)

2001-01-01

X-rays diffracted from a well-ordered protein crystal create sharp patterns of scattered light on film. A computer can use these patterns to generate a model of a protein molecule. To analyze the selected crystal, an X-ray crystallographer shines X-rays through the crystal. Unlike a single dental X-ray, which produces a shadow image of a tooth, these X-rays have to be taken many times from different angles to produce a pattern from the scattered light, a map of the intensity of the X-rays after they diffract through the crystal. The X-rays bounce off the electron clouds that form the outer structure of each atom. A flawed crystal will yield a blurry pattern; a well-ordered protein crystal yields a series of sharp diffraction patterns. From these patterns, researchers build an electron density map. With powerful computers and a lot of calculations, scientists can use the electron density patterns to determine the structure of the protein and make a computer-generated model of the structure. The models let researchers improve their understanding of how the protein functions. They also allow scientists to look for receptor sites and active areas that control a protein's function and role in the progress of diseases. From there, pharmaceutical researchers can design molecules that fit the active site, much like a key and lock, so that the protein is locked without affecting the rest of the body. This is called structure-based drug design.

On the sensitivity of protein data bank normal mode analysis: an application to GH10 xylanases

Science.gov (United States)

Tirion, Monique M.

2015-12-01

Protein data bank entries obtain distinct, reproducible flexibility characteristics determined by normal mode analyses of their three dimensional coordinate files. We study the effectiveness and sensitivity of this technique by analyzing the results on one class of glycosidases: family 10 xylanases. A conserved tryptophan that appears to affect access to the active site can be in one of two conformations according to x-ray crystallographic electron density data. The two alternate orientations of this active site tryptophan lead to distinct flexibility spectra, with one orientation thwarting the oscillations seen in the other. The particular orientation of this sidechain furthermore affects the appearance of the motility of a distant, C terminal region we term the mallet. The mallet region is known to separate members of this family of enzymes into two classes.

On the sensitivity of protein data bank normal mode analysis: an application to GH10 xylanases

International Nuclear Information System (INIS)

Tirion, Monique M

2015-01-01

Protein data bank entries obtain distinct, reproducible flexibility characteristics determined by normal mode analyses of their three dimensional coordinate files. We study the effectiveness and sensitivity of this technique by analyzing the results on one class of glycosidases: family 10 xylanases. A conserved tryptophan that appears to affect access to the active site can be in one of two conformations according to x-ray crystallographic electron density data. The two alternate orientations of this active site tryptophan lead to distinct flexibility spectra, with one orientation thwarting the oscillations seen in the other. The particular orientation of this sidechain furthermore affects the appearance of the motility of a distant, C terminal region we term the mallet. The mallet region is known to separate members of this family of enzymes into two classes. (paper)

Quaternary ammonium oxidative demethylation: X-ray crystallographic, resonance Raman, and UV-visible spectroscopic analysis of a Rieske-type demethylase.

Science.gov (United States)

Daughtry, Kelly D; Xiao, Youli; Stoner-Ma, Deborah; Cho, Eunsun; Orville, Allen M; Liu, Pinghua; Allen, Karen N

2012-02-08

Herein, the structure resulting from in situ turnover in a chemically challenging quaternary ammonium oxidative demethylation reaction was captured via crystallographic analysis and analyzed via single-crystal spectroscopy. Crystal structures were determined for the Rieske-type monooxygenase, stachydrine demethylase, in the unliganded state (at 1.6 Å resolution) and in the product complex (at 2.2 Å resolution). The ligand complex was obtained from enzyme aerobically cocrystallized with the substrate stachydrine (N,N-dimethylproline). The ligand electron density in the complex was interpreted as proline, generated within the active site at 100 K by the absorption of X-ray photon energy and two consecutive demethylation cycles. The oxidation state of the Rieske iron-sulfur cluster was characterized by UV-visible spectroscopy throughout X-ray data collection in conjunction with resonance Raman spectra collected before and after diffraction data. Shifts in the absorption band wavelength and intensity as a function of absorbed X-ray dose demonstrated that the Rieske center was reduced by solvated electrons generated by X-ray photons; the kinetics of the reduction process differed dramatically for the liganded complex compared to unliganded demethylase, which may correspond to the observed turnover in the crystal.

Soft x-ray measurement of internal tearing mode structure in a reversed-field pinch

International Nuclear Information System (INIS)

Chartas, G.; Hokin, S.

1991-01-01

The structure of internally resonant tearing modes has been studied in the Madison Symmetric Torus reversed-field pinch with a soft x-ray detector system consisting of an imaging array at one toroidal location and several detectors at different toroidal locations. The toroidal mode numbers of m = 1 structures are in the range n = -5, -6, -7. The modes propagate with phase velocity v = 1--6 x 10 6 cm/s, larger than the diamagnetic drift velocity v d ∼ 5 x 10 5 cm/s. Phase locking between modes with different n in manifested as a beating of soft x-ray signals which is found to be strongest near the resonant surfaces of the modes (r/a = 0.1 -- 0.5). 15 refs., 5 figs

Crystallographic and oxidation kinetic study of uranium dioxide by high temperature X-ray diffractometry

International Nuclear Information System (INIS)

Teixeira, S.R.

1981-01-01

The structural behavior of UO 2 sintered plates was studied as a function of temperature by X-ray diffractometry. All the experiments were carried out under an inert atmosphere with low oxygen content (approximated 140 ppm). The thermal expansion coefficient of UO 2 05 was found to be 10,5 x 10 - 6 0 C - 1 for temperatures above 165 0 C. Structural transformations during oxidation were observed at 170,235 and 275 0 C. The isothermal oxidation of UO 2 to U 3 O 7 follows a parabolic form and the diffusion of oxygen through the product layer U 4 O 9 is the mechanism controlling the oxidation rate. The phases observed were UO 2 (cubic) - U 4 O 9 (cubic) - U 3 O 7 (tetragonal). Activation energies of oxidation were found for different crystallographic planes (hkl). From this one can conclude that there is a preferential occupation of interstitial oxygen within the UO 2 structure. (Author) [pt

An Intraoral Miniature X-ray Tube Based on Carbon Nanotubes for Dental Radiography

OpenAIRE

Hyun Jin Kim; Hyun Nam Kim; Hamid Saeed Raza; Han Beom Park; Sung Oh Cho

2016-01-01

A miniature X-ray tube based on a carbon-nanotube electron emitter has been employed for the application to a dental radiography. The miniature X-ray tube has an outer diameter of 7 mm and a length of 47 mm. The miniature X-ray tube is operated in a negative high-voltage mode in which the X-ray target is electrically grounded. In addition, X-rays are generated only to the teeth directions using a collimator while X-rays generated to other directions are shielded. Hence, the X-ray tube can be ...

Exploring structural variability in X-ray crystallographic models using protein local optimization by torsion-angle sampling

International Nuclear Information System (INIS)

Knight, Jennifer L.; Zhou, Zhiyong; Gallicchio, Emilio; Himmel, Daniel M.; Friesner, Richard A.; Arnold, Eddy; Levy, Ronald M.

2008-01-01

Torsion-angle sampling, as implemented in the Protein Local Optimization Program (PLOP), is used to generate multiple structurally variable single-conformer models which are in good agreement with X-ray data. An ensemble-refinement approach to differentiate between positional uncertainty and conformational heterogeneity is proposed. Modeling structural variability is critical for understanding protein function and for modeling reliable targets for in silico docking experiments. Because of the time-intensive nature of manual X-ray crystallographic refinement, automated refinement methods that thoroughly explore conformational space are essential for the systematic construction of structurally variable models. Using five proteins spanning resolutions of 1.0–2.8 Å, it is demonstrated how torsion-angle sampling of backbone and side-chain libraries with filtering against both the chemical energy, using a modern effective potential, and the electron density, coupled with minimization of a reciprocal-space X-ray target function, can generate multiple structurally variable models which fit the X-ray data well. Torsion-angle sampling as implemented in the Protein Local Optimization Program (PLOP) has been used in this work. Models with the lowest R free values are obtained when electrostatic and implicit solvation terms are included in the effective potential. HIV-1 protease, calmodulin and SUMO-conjugating enzyme illustrate how variability in the ensemble of structures captures structural variability that is observed across multiple crystal structures and is linked to functional flexibility at hinge regions and binding interfaces. An ensemble-refinement procedure is proposed to differentiate between variability that is a consequence of physical conformational heterogeneity and that which reflects uncertainty in the atomic coordinates

Chandra-SDSS Normal and Star-Forming Galaxies. I. X-Ray Source Properties of Galaxies Detected by the Chandra X-Ray Observatory in SDSS DR2

Science.gov (United States)

Hornschemeier, A. E.; Heckman, T. M.; Ptak, A. F.; Tremonti, C. A.; Colbert, E. J. M.

2005-01-01

We have cross-correlated X-ray catalogs derived from archival Chandra X-Ray Observatory ACIS observations with a Sloan Digital Sky Survey Data Release 2 (DR2) galaxy catalog to form a sample of 42 serendipitously X-ray-detected galaxies over the redshift interval 0.03X-ray-studied samples of normal galaxies and those in the deepest X-ray surveys. Our chief purpose is to compare optical spectroscopic diagnostics of activity (both star formation and accretion) with X-ray properties of galaxies. Our work supports a normalization value of the X-ray-star formation rate correlation consistent with the lower values published in the literature. The difference is in the allocation of X-ray emission to high-mass X-ray binaries relative to other components, such as hot gas, low-mass X-ray binaries, and/or active galactic nuclei (AGNs). We are able to quantify a few pitfalls in the use of lower resolution, lower signal-to-noise ratio optical spectroscopy to identify X-ray sources (as has necessarily been employed for many X-ray surveys). Notably, we find a few AGNs that likely would have been misidentified as non-AGN sources in higher redshift studies. However, we do not find any X-ray-hard, highly X-ray-luminous galaxies lacking optical spectroscopic diagnostics of AGN activity. Such sources are members of the ``X-ray-bright, optically normal galaxy'' (XBONG) class of AGNs.

X-ray Microprobe for Fluorescence and Diffraction Analysis

International Nuclear Information System (INIS)

Ice, G.E.

2005-01-01

X-ray diffraction (see unit 1.1) and x-ray excited fluorescence analysis are powerful techniques for the nondestructive measurement of crystal structure and chemical composition. X-ray fluorescence analysis is inherently nondestructive with orders of magnitude lower power deposited for the same detectable limit as with fluorescence excited by charged particle probes (Sparks, 1980). X-ray diffraction analysis is sensitive to crystal structure with orders-of-magnitude greater sensitivity to crystallographic strain than electron probes (Rebonato, et al. 1989). When a small-area x-ray microbeam is used as the probe, chemical composition (Z>14), crystal structure, crystalline texture, and crystalline strain distributions can be determined. These distributions can be studied both at the surface of the sample and deep within the sample (Fig. 1). Current state-of-the-art can achieve an ∼1 mm-D x-ray microprobe and an ∼0.1 mm-D x-ray microprobe has been demonstrated (Bilderback, et al., 1994). Despite their great chemical and crystallographic sensitivities, x-ray microprobe techniques have until recently been restricted by inefficient x-ray focusing optics and weak x-ray sources; x-ray microbeam analysis was largely superseded by electron techniques in the 50's. However, interest in x-ray microprobe techniques has now been revived (Howells, et al., 1983; Ice and Sparks, 1984; Chevallier, et al., 1997; Riekel 1992; Thompson, el al., 1992; and Making and Using... 1997) by the development of efficient x-ray focusing optics and ultra-high intensity synchrotron x-ray sources (Buras and Tazzari, 1984; Shenoy, et al., 1988). These advances have increased the achievable microbeam flux by more than 11 orders of magnitude (Fig. 2) (Ice, 1997); the flux in a tunable 1 mm-D beam on a 'so called' 3rd-generation synchrotron source such as the APS can exceed the flux in a fixed-energy mm2 beam on a conventional source. These advances make x-ray microfluorescence and x-ray

Influence of Bernstein modes on the efficiency of electron cyclotron resonance x-ray source

International Nuclear Information System (INIS)

Andreev, V. V.; Nikitin, G.V.; Savanovich, V.Yu.; Umnov, A.M.; Elizarov, L.I.; Serebrennikov, K.S.; Vostrikova, E.A.

2006-01-01

The article considers the factors influencing the temperature of hot electron component in an electron cyclotron resonance (ECR) x-ray source. In such sources the electron heating occurs often due to extraordinary electromagnetic wave propagating perpendicularly to the magnetic field. In this case the possibility of the absorption of Bernstein modes is regarded as an additional mechanism of electron heating. The Bernstein modes in an ECR x-ray source can arise due to either linear transformation or parametric instability of external transversal wave. The article briefly reviews also the further experiments which will be carried out to study the influence of Bernstein modes on the increase of hot electron temperature and consequently of x-ray emission

Site- and phase-selective x-ray absorption spectroscopy based on phase-retrieval calculation

International Nuclear Information System (INIS)

Kawaguchi, Tomoya; Fukuda, Katsutoshi; Matsubara, Eiichiro

2017-01-01

Understanding the chemical state of a particular element with multiple crystallographic sites and/or phases is essential to unlocking the origin of material properties. To this end, resonant x-ray diffraction spectroscopy (RXDS) achieved through a combination of x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) techniques can allow for the measurement of diffraction anomalous fine structure (DAFS). This is expected to provide a peerless tool for electronic/local structural analyses of materials with complicated structures thanks to its capability to extract spectroscopic information about a given element at each crystallographic site and/or phase. At present, one of the major challenges for the practical application of RXDS is the rigorous determination of resonant terms from observed DAFS, as this requires somehow determining the phase change in the elastic scattering around the absorption edge from the scattering intensity. This is widely known in the field of XRD as the phase problem. The present review describes the basics of this problem, including the relevant background and theory for DAFS and a guide to a newly-developed phase-retrieval method based on the logarithmic dispersion relation that makes it possible to analyze DAFS without suffering from the intrinsic ambiguities of conventional iterative-fitting. Several matters relating to data collection and correction of RXDS are also covered, with a final emphasis on the great potential of powder-sample-based RXDS (P-RXDS) to be used in various applications relevant to practical materials, including antisite-defect-type electrode materials for lithium-ion batteries. (topical review)

X-ray metrology for ULSI structures

International Nuclear Information System (INIS)

Bowen, D. K.; Matney, K. M.; Wormington, M.

1998-01-01

Non-destructive X-ray metrological methods are discussed for application to both process development and process control of ULSI structures. X-ray methods can (a) detect the unacceptable levels of internal defects generated by RTA processes in large wafers, (b) accurately measure the thickness and roughness of layers between 1 and 1000 nm thick and (c) can monitor parameters such as crystallographic texture and the roughness of buried interfaces. In this paper we review transmission X-ray topography, thin film texture measurement, grazing-incidence X-ray reflectivity and high-resolution X-ray diffraction. We discuss in particular their suitability as on-line sensors for process control

Deriving Quantitative Crystallographic Information from the Wavelength-Resolved Neutron Transmission Analysis Performed in Imaging Mode

Directory of Open Access Journals (Sweden)

Hirotaka Sato

2017-12-01

Full Text Available Current status of Bragg-edge/dip neutron transmission analysis/imaging methods is presented. The method can visualize real-space distributions of bulk crystallographic information in a crystalline material over a large area (~10 cm with high spatial resolution (~100 μm. Furthermore, by using suitable spectrum analysis methods for wavelength-dependent neutron transmission data, quantitative visualization of the crystallographic information can be achieved. For example, crystallographic texture imaging, crystallite size imaging and crystalline phase imaging with texture/extinction corrections are carried out by the Rietveld-type (wide wavelength bandwidth profile fitting analysis code, RITS (Rietveld Imaging of Transmission Spectra. By using the single Bragg-edge analysis mode of RITS, evaluations of crystal lattice plane spacing (d-spacing relating to macro-strain and d-spacing distribution’s FWHM (full width at half maximum relating to micro-strain can be achieved. Macro-strain tomography is performed by a new conceptual CT (computed tomography image reconstruction algorithm, the tensor CT method. Crystalline grains and their orientations are visualized by a fast determination method of grain orientation for Bragg-dip neutron transmission spectrum. In this paper, these imaging examples with the spectrum analysis methods and the reliabilities evaluated by optical/electron microscope and X-ray/neutron diffraction, are presented. In addition, the status at compact accelerator driven pulsed neutron sources is also presented.

A synthesis, X-ray crystallographic and vibrational studies of guanidinium o-nitrobenzoate hydrate. New NLO crystal in guanidinium nitrobenzoate family

Science.gov (United States)

Drozd, Marek; Daszkiewicz, Marek

2018-06-01

According to literature data the two crystals are known: guanidinium m-nitrobenzoate and guanidinium p-nitrobenzoate. Both compounds belong to noncetrosymmetric crystallographic systems are consider as second order generators in nonlinear optic (NLO). For each of these crystals the detailed crystallographic, theoretical calculations and vibrational studies were performed. It is interesting that nitrobenzoic acid create tree variety of compounds ((2) ortho-, (3) meta- and (4) para-) what any data for third member of guanidinium nitrobenzoate crystal were not known. The guanidinium o-nitrobenzoate hydrate crystal was synthesized first time. The performed X-ray crystallographic study shown that crystal belongs to space group without macroscopic symmetry center. Additionally, the vibrational spectra (intensities, frequencies and PED analysis) of investigated compound are presented. These results are compared with theoretical calculations for equilibrium geometry and vibrational properties. Furthermore, the results of the theoretical approach include HOMO and LUMO energies and first order hyperpolarizability were obtained, also. On the basis of these data the crystal was classified as second order generator. All obtained results are compared with previous literature data of guanidinium m-nitrobenzoate and guanidinium p-nitrobenzoate compounds. Surprisingly, each of examined crystal belongs to different crystallographic system and shows different vibrational properties.

Sequential x-ray diffraction topography at 1-BM x-ray optics testing beamline at the advanced photon source

Energy Technology Data Exchange (ETDEWEB)

Stoupin, Stanislav, E-mail: sstoupin@aps.anl.gov; Shvyd’ko, Yuri; Trakhtenberg, Emil; Liu, Zunping; Lang, Keenan; Huang, Xianrong; Wieczorek, Michael; Kasman, Elina; Hammonds, John; Macrander, Albert; Assoufid, Lahsen [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States)

2016-07-27

We report progress on implementation and commissioning of sequential X-ray diffraction topography at 1-BM Optics Testing Beamline of the Advanced Photon Source to accommodate growing needs of strain characterization in diffractive crystal optics and other semiconductor single crystals. The setup enables evaluation of strain in single crystals in the nearly-nondispersive double-crystal geometry. Si asymmetric collimator crystals of different crystallographic orientations were designed, fabricated and characterized using in-house capabilities. Imaging the exit beam using digital area detectors permits rapid sequential acquisition of X-ray topographs at different angular positions on the rocking curve of a crystal under investigation. Results on sensitivity and spatial resolution are reported based on experiments with high-quality Si and diamond crystals. The new setup complements laboratory-based X-ray topography capabilities of the Optics group at the Advanced Photon Source.

Data analysis of x-ray fluorescence holography by subtracting normal component from inverse hologram

International Nuclear Information System (INIS)

Happo, Naohisa; Hayashi, Kouichi; Hosokawa, Shinya

2010-01-01

X-ray fluorescence holography (XFH) is a powerful technique for determining three-dimensional local atomic arrangements around a specific fluorescing element. However, the raw experimental hologram is predominantly a mixed hologram, i.e., a mixture of hologram generated in both normal and inverse modes, which produces unreliable atomic images. In this paper, we propose a practical subtraction method of the normal component from the inverse XFH data by a Fourier transform for the calculated hologram of a model ZnTe cluster. Many spots originating from the normal components could be properly removed using a mask function, and clear atomic images were reconstructed at adequate positions of the model cluster. This method was successfully applied to the analysis of experimental ZnTe single crystal XFH data. (author)

CCD-based X-ray detectors for X-ray diffraction studies

International Nuclear Information System (INIS)

Ito, K.; Amemiya, Y.

1999-01-01

CCD-based X-ray detectors are getting to be used for X-ray diffraction studies especially in the studies where real time (automated) measurements and time-resolved measurements are required. Principles and designs of two typical types of CCD-based detectors are described; one is ths system in which x-ray image intensifiers are coupled to maximize the detective quantum efficiency for time-resolved measurements, and the other is the system in which tapered optical fibers are coupled for the reduction of the image into the CCD, which is optimized for automated measurements for protein crystallography. These CCD-based X-ray detectors have an image distortion and non-uniformity of response to be corrected by software. Correction schemes which we have developed are also described. (author)

Analyzing x-ray hotspot images with Ince-Gaussian modes

Science.gov (United States)

Kruse, Michael; Field, John; Nora, Ryan; Benedetti, Robin; Khan, Shahab; Ma, Tammy; Peterson, Luc; Spears, Brian

2017-10-01

X-ray images at the National Ignition Facility (NIF) provide important metrics regarding the shape of the hotspot along a given line-of-sight. The 17% contour from peak brightness is usually used to infer the size of the hotspot as well as determine shape perturbations quantified through the Legendre coefficients P2 and P4. Unfortunately features that lie inside the contour such as those that could arise from tent or fill-tube perturbations are not easily captured. An analysis that takes into account the two-dimensional nature of the x-ray image is desirable. Ince-Gaussian modes (for short: Ince) offer such an analysis and could provide a new way to encode and understand the images recorded at NIF. The Ince modes are the solutions to the paraxial wave equation expressed in elliptical coordinates and thus form an orthonormal basis. Due to their elliptical nature they are suitable for decomposing images that have a non-zero P2 or P4 coefficient. We show that the Ince modes can be used to uncover structure that is missed by the contour analysis and how the modes aid in compressing images produced in large ensemble calculations. Finally a comparison is made to the Zernike modes which form an orthonormal basis on a circular disk. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-734741.

Photovoltaic X-ray detectors based on epitaxial GaAs structures

Energy Technology Data Exchange (ETDEWEB)

Achmadullin, R.A. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Artemov, V.V. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, 59 Leninski pr., Moscow B-333, 117333 (Russian Federation); Dvoryankin, V.F. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation)]. E-mail: vfd217@ire216.msk.su; Dvoryankina, G.G. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Dikaev, Yu.M. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Ermakov, M.G. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Ermakova, O.N. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Chmil, V.B. [Scientific State Center, High Energy Physics Institute, Protvino, Moscow region (Russian Federation); Holodenko, A.G. [Scientific State Center, High Energy Physics Institute, Protvino, Moscow region (Russian Federation); Kudryashov, A.A.; Krikunov, A.I.; Petrov, A.G.; Telegin, A.A. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Vorobiev, A.P. [Scientific State Center, High Energy Physics Institute, Protvino, Moscow region (Russian Federation)

2005-12-01

A new type of the photovoltaic X-ray detector based on epitaxial p{sup +}-n-n'-n{sup +} GaAs structures which provides a high efficiency of charge collection in the non-bias operation mode at room temperature is proposed. The GaAs epitaxial structures were grown by vapor-phase epitaxy on heavily doped n{sup +}-GaAs(1 0 0) substrates. The absorption efficiency of GaAs X-ray detector is discussed. I-V and C-V characteristics of the photovoltaic X-ray detectors are analyzed. The built-in electric field profiles in the depletion region of epitaxial structures are measured by the EBIC method. Charge collection efficiency to {alpha}-particles and {gamma}-radiation are measured. The application of X-ray detectors is discussed.

Macromolecular crystallographic results obtained using a 2048x2048 CCD detector at CHESS

International Nuclear Information System (INIS)

Thiel, D.J.; Ealick, S.E.; Tate, M.W.; Gruner, S.M.; Eikenberry, E.F.

1996-01-01

We present results of macromolecular crystallographic experiments performed at the Cornell High Energy Synchrotron Source (CHESS) with a new CCD-based detector. This detector, installed in January 1995, complements a 1024x1024 CCD detector that has been in continuous operation at CHESS since December 1993. The new detector is based on a 4-port, 2048x2048 pixel CCD that is directly coupled to a Gd 2 O 2 S:Tb phosphor by a 3:1 tapered fiber optic. The active area of the phosphor is a square 82 mm on an edge. The readout time is 7 seconds. In the standard mode of operation, the pixel size at the active area is 41 μm on the edge leading to the capability of resolving approximately 200 orders of diffraction across the detector face. The detector also operates in a 1024x1024 mode in which the pixel size is electronically increased by a factor of 4 in area resulting in smaller data files and faster detector readout but at the expense of spatial resolution. Most of the data that has been collected by this detector has been collected in this mode. Dozens of data sets have been collected by many experimenters using this detector at CHESS during the four month period from its installation until the start of the six-month down period of the storage ring. The capabilities of the detector will be illustrated with results from various crystallographic measurements including experiments in which the recorded diffraction patterns extend in resolution as far as 1 A. The results demonstrate that this detector is capable of collecting data of quality at least equal to that of imaging plates but, in many circumstances, with much greater beamline efficiency. copyright 1996 American Institute of Physics

Synchronous x-ray and radio mode switches: a rapid global transformation of the pulsar magnetosphere.

Science.gov (United States)

Hermsen, W; Hessels, J W T; Kuiper, L; van Leeuwen, J; Mitra, D; de Plaa, J; Rankin, J M; Stappers, B W; Wright, G A E; Basu, R; Alexov, A; Coenen, T; Grießmeier, J-M; Hassall, T E; Karastergiou, A; Keane, E; Kondratiev, V I; Kramer, M; Kuniyoshi, M; Noutsos, A; Serylak, M; Pilia, M; Sobey, C; Weltevrede, P; Zagkouris, K; Asgekar, A; Avruch, I M; Batejat, F; Bell, M E; Bell, M R; Bentum, M J; Bernardi, G; Best, P; Bîrzan, L; Bonafede, A; Breitling, F; Broderick, J; Brüggen, M; Butcher, H R; Ciardi, B; Duscha, S; Eislöffel, J; Falcke, H; Fender, R; Ferrari, C; Frieswijk, W; Garrett, M A; de Gasperin, F; de Geus, E; Gunst, A W; Heald, G; Hoeft, M; Horneffer, A; Iacobelli, M; Kuper, G; Maat, P; Macario, G; Markoff, S; McKean, J P; Mevius, M; Miller-Jones, J C A; Morganti, R; Munk, H; Orrú, E; Paas, H; Pandey-Pommier, M; Pandey, V N; Pizzo, R; Polatidis, A G; Rawlings, S; Reich, W; Röttgering, H; Scaife, A M M; Schoenmakers, A; Shulevski, A; Sluman, J; Steinmetz, M; Tagger, M; Tang, Y; Tasse, C; ter Veen, S; Vermeulen, R; van de Brink, R H; van Weeren, R J; Wijers, R A M J; Wise, M W; Wucknitz, O; Yatawatta, S; Zarka, P

2013-01-25

Pulsars emit from low-frequency radio waves up to high-energy gamma-rays, generated anywhere from the stellar surface out to the edge of the magnetosphere. Detecting correlated mode changes across the electromagnetic spectrum is therefore key to understanding the physical relationship among the emission sites. Through simultaneous observations, we detected synchronous switching in the radio and x-ray emission properties of PSR B0943+10. When the pulsar is in a sustained radio-"bright" mode, the x-rays show only an unpulsed, nonthermal component. Conversely, when the pulsar is in a radio-"quiet" mode, the x-ray luminosity more than doubles and a 100% pulsed thermal component is observed along with the nonthermal component. This indicates rapid, global changes to the conditions in the magnetosphere, which challenge all proposed pulsar emission theories.

Response of cultured normal human mammary epithelial cells to X rays

International Nuclear Information System (INIS)

Yang, T.C.; Stampfer, M.R.; Smith, H.S.

1983-01-01

The effect of X rays on the reproductive death of cultured normal human mammary epithelial cells was examined. Techniques were developed for isolating and culturing normal human mammary epithelial cells which provide sufficient cells at second passage for radiation studies, and an efficient clonogenic assay suitable for measuring radiation survival curves. It was found that the survival curves for epithelial cells from normal breast tissue were exponential and had D 0 values of about 109-148 rad for 225 kVp X rays. No consistent change in cell radiosensitivity with the age of donor was observed, and no sublethal damage repair in these cells could be detected with the split-dose technique

New opportunities for 3D materials science of polycrystalline materials at the micrometre lengthscale by combined use of X-ray diffraction and X-ray imaging

Energy Technology Data Exchange (ETDEWEB)

Ludwig, W., E-mail: ludwig@esrf.fr [Universite de Lyon, INSA-Lyon, MATEIS CNRS UMR 5510, 69621Villeurbanne (France); European Synchrotron Radiation Facility, BP220, 38043 Grenoble (France); King, A. [European Synchrotron Radiation Facility, BP220, 38043 Grenoble (France); School of Materials, University of Manchester, Manchester, M13 9PL (United Kingdom); Reischig, P. [European Synchrotron Radiation Facility, BP220, 38043 Grenoble (France); Herbig, M. [Universite de Lyon, INSA-Lyon, MATEIS CNRS UMR 5510, 69621Villeurbanne (France); Lauridsen, E.M.; Schmidt, S. [Riso National Laboratory for Sustainable Energy, Technical University of Denmark, P.O. Box 49, DK-4000 Roskilde (Denmark); Proudhon, H.; Forest, S. [MINES ParisTech, Centre des materiaux, CNRS UMR 7633, BP 87, 91003 Evry Cedex (France); Cloetens, P.; Roscoat, S. Rolland du [European Synchrotron Radiation Facility, BP220, 38043 Grenoble (France); Buffiere, J.Y. [Universite de Lyon, INSA-Lyon, MATEIS CNRS UMR 5510, 69621Villeurbanne (France); Marrow, T.J. [School of Materials, University of Manchester, Manchester, M13 9PL (United Kingdom); Poulsen, H.F. [Riso National Laboratory for Sustainable Energy, Technical University of Denmark, P.O. Box 49, DK-4000 Roskilde (Denmark)

2009-10-25

Non-destructive, three-dimensional (3D) characterization of the grain structure in mono-phase polycrystalline materials is an open challenge in material science. Recent advances in synchrotron based X-ray imaging and diffraction techniques offer interesting possibilities for mapping 3D grain shapes and crystallographic orientations for certain categories of polycrystalline materials. Direct visualisation of the three-dimensional grain boundary network or of two-phase (duplex) grain structures by means of absorption and/or phase contrast techniques may be possible, but is restricted to specific material systems. A recent extension of this methodology, termed X-ray diffraction contrast tomography (DCT), combines the principles of X-ray diffraction imaging, three-dimensional X-ray diffraction microscopy (3DXRD) and image reconstruction from projections. DCT provides simultaneous access to 3D grain shape, crystallographic orientation and local attenuation coefficient distribution. The technique applies to the larger range of plastically undeformed, polycrystalline mono-phase materials, provided some conditions on grain size and texture are fulfilled. The straightforward combination with high-resolution microtomography opens interesting new possibilities for the observation of microstructure related damage and deformation mechanisms in these materials.

New opportunities for 3D materials science of polycrystalline materials at the micrometre lengthscale by combined use of X-ray diffraction and X-ray imaging

International Nuclear Information System (INIS)

Ludwig, W.; King, A.; Reischig, P.; Herbig, M.; Lauridsen, E.M.; Schmidt, S.; Proudhon, H.; Forest, S.; Cloetens, P.; Roscoat, S. Rolland du; Buffiere, J.Y.; Marrow, T.J.; Poulsen, H.F.

2009-01-01

Non-destructive, three-dimensional (3D) characterization of the grain structure in mono-phase polycrystalline materials is an open challenge in material science. Recent advances in synchrotron based X-ray imaging and diffraction techniques offer interesting possibilities for mapping 3D grain shapes and crystallographic orientations for certain categories of polycrystalline materials. Direct visualisation of the three-dimensional grain boundary network or of two-phase (duplex) grain structures by means of absorption and/or phase contrast techniques may be possible, but is restricted to specific material systems. A recent extension of this methodology, termed X-ray diffraction contrast tomography (DCT), combines the principles of X-ray diffraction imaging, three-dimensional X-ray diffraction microscopy (3DXRD) and image reconstruction from projections. DCT provides simultaneous access to 3D grain shape, crystallographic orientation and local attenuation coefficient distribution. The technique applies to the larger range of plastically undeformed, polycrystalline mono-phase materials, provided some conditions on grain size and texture are fulfilled. The straightforward combination with high-resolution microtomography opens interesting new possibilities for the observation of microstructure related damage and deformation mechanisms in these materials.

Numerical simulation study for atomic-resolution x-ray fluorescence holography

International Nuclear Information System (INIS)

Xie Honglan; Gao Hongyi; Chen Jianwen; Xiong Shisheng; Xu Zhizhan; Wang Junyue; Zhu Peiping; Xian Dingchang

2003-01-01

Based on the principle of x-ray fluorescence holography, an iron single crystal model of a body-centred cubic lattice is numerically simulated. From the fluorescence hologram produced numerically, the Fe atomic images were reconstructed. The atomic images of the (001), (100), (010) crystallographic planes were consistent with the corresponding atomic positions of the model. The result indicates that one can obtain internal structure images of single crystals at atomic-resolution by using x-ray fluorescence holography

An introduction to three-dimensional X-ray diffraction microscopy

DEFF Research Database (Denmark)

Poulsen, Henning Friis

2012-01-01

Three-dimensional X-ray diffraction microscopy is a fast and nondestructive structural characterization technique aimed at studies of the individual crystalline elements (grains or subgrains) within millimetre-sized polycrystalline specimens. It is based on two principles: the use of highly...... penetrating hard X-rays from a synchrotron source and the application of tomographic reconstruction algorithms for the analysis of the diffraction data. In favourable cases, the position, morphology, phase and crystallographic orientation can be derived for up to 1000 elements simultaneously. For each grain...

A split-beam probe-pump-probe scheme for femtosecond time resolved protein X-ray crystallography

Directory of Open Access Journals (Sweden)

Jasper J. van Thor

2015-01-01

Full Text Available In order to exploit the femtosecond pulse duration of X-ray Free-Electron Lasers (XFEL operating in the hard X-ray regime for ultrafast time-resolved protein crystallography experiments, critical parameters that determine the crystallographic signal-to-noise (I/σI must be addressed. For single-crystal studies under low absorbed dose conditions, it has been shown that the intrinsic pulse intensity stability as well as mode structure and jitter of this structure, significantly affect the crystallographic signal-to-noise. Here, geometrical parameters are theoretically explored for a three-beam scheme: X-ray probe, optical pump, X-ray probe (or “probe-pump-probe” which will allow experimental determination of the photo-induced structure factor amplitude differences, ΔF, in a ratiometric manner, thereby internally referencing the intensity noise of the XFEL source. In addition to a non-collinear split-beam geometry which separates un-pumped and pumped diffraction patterns on an area detector, applying an additional convergence angle to both beams by focusing leads to integration over mosaic blocks in the case of well-ordered stationary protein crystals. Ray-tracing X-ray diffraction simulations are performed for an example using photoactive yellow protein crystals in order to explore the geometrical design parameters which would be needed. The specifications for an X-ray split and delay instrument that implements both an offset angle and focused beams are discussed, for implementation of a probe-pump-probe scheme at the European XFEL. We discuss possible extension of single crystal studies to serial femtosecond crystallography, particularly in view of the expected X-ray damage and ablation due to the first probe pulse.

An Intraoral Miniature X-ray Tube Based on Carbon Nanotubes for Dental Radiography

Directory of Open Access Journals (Sweden)

Hyun Jin Kim

2016-06-01

Full Text Available A miniature X-ray tube based on a carbon-nanotube electron emitter has been employed for the application to a dental radiography. The miniature X-ray tube has an outer diameter of 7 mm and a length of 47 mm. The miniature X-ray tube is operated in a negative high-voltage mode in which the X-ray target is electrically grounded. In addition, X-rays are generated only to the teeth directions using a collimator while X-rays generated to other directions are shielded. Hence, the X-ray tube can be safely inserted into a human mouth. Using the intra-oral X-ray tube, a dental radiography is demonstrated where the positions of an X-ray source and a sensor are reversed compared with a conventional dental radiography system. X-ray images of five neighboring teeth are obtained and, furthermore, both left and right molar images are achieved by a single X-ray shot of the miniature X-ray tube.

An intraoral miniature x-ray tube based on carbon nanotubes for dental radiography

International Nuclear Information System (INIS)

Kim, Hyun Jin; Kim, Hyun Nam; Raza, Hamid Saeed; Park, Han Beom; Cho, Sung Oh

2016-01-01

A miniature X-ray tube based on a carbon-nanotube electron emitter has been employed for the application to a dental radiography. The miniature X-ray tube has an outer diameter of 7 mm and a length of 47 mm. The miniature X-ray tube is operated in a negative high-voltage mode in which the X-ray target is electrically grounded. In addition, X-rays are generated only to the teeth directions using a collimator while X-rays generated to other directions are shielded. Hence, the X-ray tube can be safely inserted into a human mouth. Using the intra-oral X-ray tube, a dental radiography is demonstrated where the positions of an X-ray source and a sensor are reversed compared with a conventional dental radiography system. X-ray images of five neighboring teeth are obtained and, furthermore, both left and right molar images are achieved by a single X-ray shot of the miniature X-ray tube

An intraoral miniature x-ray tube based on carbon nanotubes for dental radiography

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Jin; Kim, Hyun Nam; Raza, Hamid Saeed; Park, Han Beom; Cho, Sung Oh [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

2016-06-15

A miniature X-ray tube based on a carbon-nanotube electron emitter has been employed for the application to a dental radiography. The miniature X-ray tube has an outer diameter of 7 mm and a length of 47 mm. The miniature X-ray tube is operated in a negative high-voltage mode in which the X-ray target is electrically grounded. In addition, X-rays are generated only to the teeth directions using a collimator while X-rays generated to other directions are shielded. Hence, the X-ray tube can be safely inserted into a human mouth. Using the intra-oral X-ray tube, a dental radiography is demonstrated where the positions of an X-ray source and a sensor are reversed compared with a conventional dental radiography system. X-ray images of five neighboring teeth are obtained and, furthermore, both left and right molar images are achieved by a single X-ray shot of the miniature X-ray tube.

Exploring anti-correlated radio/X-ray modes in transitional millisecond pulsars

Science.gov (United States)

Jaodand, Amruta

2017-09-01

Recently, using coordinated VLA+Chandra observations, Bogdanov et al.(2017) have uncovered a stunning anti-correlation in the LMXB state of the tMSP PSR J1023+0038. They see that radio luminosity consistently peaks during the X-ray `low' luminosity modes. Also, we have found a promising candidate tMSP, 3FGL J1544-1125(J1544) (Bogdanov and Halpern 2015; currently only tMSP candidate apart from J1023 in a persistent LMXB state). Using VLA and simultaneous Swift observations we see that it lies on the proposed tMSP track in radio vs. X-ray luminosity (L_ R/L_X) diagram. This finding strengthens its classification as a tMSP and provides an excellent opportunity to a)determine universality of radio/X-ray brightness anti-correlatio and b)understand jet/outflow formation in tMSPs.

The normalization of solar X-ray data from many experiments.

Science.gov (United States)

Wende, C. D.

1972-01-01

A conversion factor is used to convert Geiger (GM) tube count rates or ion chamber currents into units of the incident X-ray energy flux in a specified passband. A method is described which varies the passband to optimize these conversion factors such that they are relatively independent of the spectrum of the incident photons. This method was applied to GM tubes flown on Explorers 33 and 35 and Mariner 5 and to ion chambers flown on OSO 3 and OGO 4. Revised conversion factors and passbands are presented, and the resulting absolute solar X-ray fluxes based on these are shown to improve the agreement between the various experiments. Calculations have shown that, although the GM tubes on Explorer 33 viewed the Sun off-axis, the effective passband did not change appreciably, and the simple normalization of the count rates to the count rates of a similar GM tube on Explorer 35 was justified.

NOMAD-Ref: visualization, deformation and refinement of macromolecular structures based on all-atom normal mode analysis.

Science.gov (United States)

Lindahl, Erik; Azuara, Cyril; Koehl, Patrice; Delarue, Marc

2006-07-01

Normal mode analysis (NMA) is an efficient way to study collective motions in biomolecules that bypasses the computational costs and many limitations associated with full dynamics simulations. The NOMAD-Ref web server presented here provides tools for online calculation of the normal modes of large molecules (up to 100,000 atoms) maintaining a full all-atom representation of their structures, as well as access to a number of programs that utilize these collective motions for deformation and refinement of biomolecular structures. Applications include the generation of sets of decoys with correct stereochemistry but arbitrary large amplitude movements, the quantification of the overlap between alternative conformations of a molecule, refinement of structures against experimental data, such as X-ray diffraction structure factors or Cryo-EM maps and optimization of docked complexes by modeling receptor/ligand flexibility through normal mode motions. The server can be accessed at the URL http://lorentz.immstr.pasteur.fr/nomad-ref.php.

Reflection-mode x-ray powder diffraction cell for in situ studies of electrochemical reactions

International Nuclear Information System (INIS)

Roberts, G.A.; Stewart, K.D.

2004-01-01

The design and operation of an electrochemical cell for reflection-mode powder x-ray diffraction experiments are discussed. The cell is designed for the study of electrodes that are used in rechargeable lithium batteries. It is designed for assembly in a glove box so that air-sensitive materials, such as lithium foil electrodes and carbonate-based electrolytes with lithium salts, can be used. The cell uses a beryllium window for x-ray transmission and electrical contact. A simple mechanism for compressing the electrodes is included in the design. Sample results for the cell are shown with a Cu Kα source and a position-sensitive detector

X-ray crystallographic characterization of rhesus macaque MHC Mamu-A*02 complexed with an immunodominant SIV-Gag nonapeptide

International Nuclear Information System (INIS)

Feng, Youjun; Qi, Jianxun; Zhang, Huimin; Wang, Jinzi; Liu, Jinhua; Jiang, Fan; Gao, Feng

2005-01-01

X-ray crystallographic characterization of rhesus macaque MHC Mamu-A*02 complexed with an immunodominant SIV-Gag nonapeptide. Simian immunodeficiency virus (SIV) in the rhesus macaque is regarded as a classic animal model, playing a crucial role in HIV vaccine strategies and therapeutics by characterizing various cytotoxic T-lymphocyte (CTL) responses in macaque monkeys. However, the availability of well documented structural reports focusing on rhesus macaque major histocompatibility complex class I (MHC I) molecules remains extremely limited. Here, a complex of the rhesus macaque MHC I molecule (Mamu-A*02) with human β 2 m and an immunodominant SIV-Gag nonapeptide, GESNLKSLY (GY9), has been crystallized. The crystal diffracts X-rays to 2.7 Å resolution and belongs to space group C2, with unit-cell parameters a = 124.11, b = 110.45, c = 100.06 Å, and contains two molecules in the asymmetric unit. The availability of the structure, which is being solved by molecular replacement, will provide new insights into rhesus macaque MHC I (Mamu-A*02) presenting pathogenic SIV peptides

X-ray crystallographic characterization of rhesus macaque MHC Mamu-A*02 complexed with an immunodominant SIV-Gag nonapeptide

Energy Technology Data Exchange (ETDEWEB)

Feng, Youjun [Laboratory of Molecular Immunology and Molecular Virology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080 (China); Graduate School, Chinese Academy of Sciences, Beijing (China); Qi, Jianxun [Graduate School, Chinese Academy of Sciences, Beijing (China); Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Zhang, Huimin; Wang, Jinzi [Laboratory of Molecular Immunology and Molecular Virology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080 (China); Liu, Jinhua [College of Veterinary Medicine, China Agricultural University, Beijing 100094 (China); Jiang, Fan [Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Gao, Feng, E-mail: gaofeng@im.ac.cn [Laboratory of Molecular Immunology and Molecular Virology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080 (China); College of Veterinary Medicine, China Agricultural University, Beijing 100094 (China)

2006-01-01

X-ray crystallographic characterization of rhesus macaque MHC Mamu-A*02 complexed with an immunodominant SIV-Gag nonapeptide. Simian immunodeficiency virus (SIV) in the rhesus macaque is regarded as a classic animal model, playing a crucial role in HIV vaccine strategies and therapeutics by characterizing various cytotoxic T-lymphocyte (CTL) responses in macaque monkeys. However, the availability of well documented structural reports focusing on rhesus macaque major histocompatibility complex class I (MHC I) molecules remains extremely limited. Here, a complex of the rhesus macaque MHC I molecule (Mamu-A*02) with human β{sub 2}m and an immunodominant SIV-Gag nonapeptide, GESNLKSLY (GY9), has been crystallized. The crystal diffracts X-rays to 2.7 Å resolution and belongs to space group C2, with unit-cell parameters a = 124.11, b = 110.45, c = 100.06 Å, and contains two molecules in the asymmetric unit. The availability of the structure, which is being solved by molecular replacement, will provide new insights into rhesus macaque MHC I (Mamu-A*02) presenting pathogenic SIV peptides.

Soft X-ray imaging of thick carbon-based materials using the normal incidence multilayer optics.

Science.gov (United States)

Artyukov, I A; Feschenko, R M; Vinogradov, A V; Bugayev, Ye A; Devizenko, O Y; Kondratenko, V V; Kasyanov, Yu S; Hatano, T; Yamamoto, M; Saveliev, S V

2010-10-01

The high transparency of carbon-containing materials in the spectral region of "carbon window" (lambda approximately 4.5-5nm) introduces new opportunities for various soft X-ray microscopy applications. The development of efficient multilayer coated X-ray optics operating at the wavelengths of about 4.5nm has stimulated a series of our imaging experiments to study thick biological and synthetic objects. Our experimental set-up consisted of a laser plasma X-ray source generated with the 2nd harmonics of Nd-glass laser, scandium-based thin-film filters, Co/C multilayer mirror and X-ray film UF-4. All soft X-ray images were produced with a single nanosecond exposure and demonstrated appropriate absorption contrast and detector-limited spatial resolution. A special attention was paid to the 3D imaging of thick low-density foam materials to be used in design of laser fusion targets.

Discovery and X-ray crystallographic analysis of a spiropiperidine iminohydantoin inhibitor of beta-secretase.

Science.gov (United States)

Barrow, James C; Stauffer, Shaun R; Rittle, Kenneth E; Ngo, Phung L; Yang, ZhiQiang; Selnick, Harold G; Graham, Samuel L; Munshi, Sanjeev; McGaughey, Georgia B; Holloway, M Katharine; Simon, Adam J; Price, Eric A; Sankaranarayanan, Sethu; Colussi, Dennis; Tugusheva, Katherine; Lai, Ming-Tain; Espeseth, Amy S; Xu, Min; Huang, Qian; Wolfe, Abigail; Pietrak, Beth; Zuck, Paul; Levorse, Dorothy A; Hazuda, Daria; Vacca, Joseph P

2008-10-23

A high-throughput screen at 100 microM inhibitor concentration for the BACE-1 enzyme revealed a novel spiropiperidine iminohydantoin aspartyl protease inhibitor template. An X-ray cocrystal structure with BACE-1 revealed a novel mode of binding whereby the inhibitor interacts with the catalytic aspartates via bridging water molecules. Using the crystal structure as a guide, potent compounds with good brain penetration were designed.

Purification, crystallization and preliminary X-ray crystallographic analysis of diaminopimelate epimerase from Acinetobacter baumannii

International Nuclear Information System (INIS)

Park, Jeong Soon; Lee, Woo Cheol; Song, Jung Hyun; Kim, Seung Il; Lee, Je Chul; Cheong, Chaejoon; Kim, Hye-Yeon

2012-01-01

The crystallization and preliminary X-ray crystallographic analysis of diaminopimelate epimerase from A. baumannii are reported. The meso isomer of diaminopimelate (meso-DAP) is a biosynthetic precursor of l-lysine in bacteria and plants, and is a key component of the peptidoglycan layer in the cell walls of Gram-negative and some Gram-positive bacteria. Diaminopimelate epimerase (DapF) is a pyridoxal-5′-phosphate-independent racemase which catalyses the interconversion of (6S,2S)-2,6-diaminopimelic acid (ll-DAP) and meso-DAP. In this study, DapF from Acinetobacter baumannii was overexpressed in Escherichia coli strain SoluBL21, purified and crystallized using a vapour-diffusion method. A native crystal diffracted to a resolution of 1.9 Å and belonged to space group P3 1 or P3 2 , with unit-cell parameters a = b = 74.91, c = 113.35 Å, α = β = 90, γ = 120°. There were two molecules in the asymmetric unit

Time-resolved soft x-ray absorption setup using multi-bunch operation modes at synchrotrons

International Nuclear Information System (INIS)

Stebel, L.; Sigalotti, P.; Ressel, B.; Cautero, G.; Malvestuto, M.; Capogrosso, V.; Bondino, F.; Magnano, E.; Parmigiani, F.

2011-01-01

Here, we report on a novel experimental apparatus for performing time-resolved soft x-ray absorption spectroscopy in the sub-ns time scale using non-hybrid multi-bunch mode synchrotron radiation. The present setup is based on a variable repetition rate Ti:sapphire laser (pump pulse) synchronized with the ∼500 MHz x-ray synchrotron radiation bunches and on a detection system that discriminates and singles out the significant x-ray photon pulses by means of a custom made photon counting unit. The whole setup has been validated by measuring the time evolution of the L 3 absorption edge during the melting and the solidification of a Ge single crystal irradiated by an intense ultrafast laser pulse. These results pave the way for performing synchrotron time-resolved experiments in the sub-ns time domain with variable repetition rate exploiting the full flux of the synchrotron radiation.

Interests and instrument: a micro-history of object Wh.3469 (X-ray powder diffraction camera, ca. 1940).

Science.gov (United States)

Scheffler, Robin Wolfe

2009-12-01

This paper presents a micro-history of an object in the collection of the Whipple Museum of the History of Science (accession no. Wh.3469), with an emphasis on how Wh.3469 reflects a hybrid of two different interwar British X-ray crystallographic communities, namely those based in WL Bragg's physics laboratory at the Victoria University of Manchester and the Crystallographic Laboratory at the University of Cambridge. It explores connections between Wh.3469's final design and construction and the different interests each community had in X-ray crystallography.

Method for spatially modulating X-ray pulses using MEMS-based X-ray optics

Science.gov (United States)

Lopez, Daniel; Shenoy, Gopal; Wang, Jin; Walko, Donald A.; Jung, Il-Woong; Mukhopadhyay, Deepkishore

2015-03-10

A method and apparatus are provided for spatially modulating X-rays or X-ray pulses using microelectromechanical systems (MEMS) based X-ray optics. A torsionally-oscillating MEMS micromirror and a method of leveraging the grazing-angle reflection property are provided to modulate X-ray pulses with a high-degree of controllability.

Diagnosing and mapping pulmonary emphysema on X-ray projection images: incremental value of grating-based X-ray dark-field imaging.

Science.gov (United States)

Meinel, Felix G; Schwab, Felix; Schleede, Simone; Bech, Martin; Herzen, Julia; Achterhold, Klaus; Auweter, Sigrid; Bamberg, Fabian; Yildirim, Ali Ö; Bohla, Alexander; Eickelberg, Oliver; Loewen, Rod; Gifford, Martin; Ruth, Ronald; Reiser, Maximilian F; Pfeiffer, Franz; Nikolaou, Konstantin

2013-01-01

To assess whether grating-based X-ray dark-field imaging can increase the sensitivity of X-ray projection images in the diagnosis of pulmonary emphysema and allow for a more accurate assessment of emphysema distribution. Lungs from three mice with pulmonary emphysema and three healthy mice were imaged ex vivo using a laser-driven compact synchrotron X-ray source. Median signal intensities of transmission (T), dark-field (V) and a combined parameter (normalized scatter) were compared between emphysema and control group. To determine the diagnostic value of each parameter in differentiating between healthy and emphysematous lung tissue, a receiver-operating-characteristic (ROC) curve analysis was performed both on a per-pixel and a per-individual basis. Parametric maps of emphysema distribution were generated using transmission, dark-field and normalized scatter signal and correlated with histopathology. Transmission values relative to water were higher for emphysematous lungs than for control lungs (1.11 vs. 1.06, pemphysema provides color-coded parametric maps, which show the best correlation with histopathology. In a murine model, the complementary information provided by X-ray transmission and dark-field images adds incremental diagnostic value in detecting pulmonary emphysema and visualizing its regional distribution as compared to conventional X-ray projections.

Expression, crystallization and preliminary X-ray analysis of the phosphoribosylglycinamide formyltransferase from Streptococcus mutans

International Nuclear Information System (INIS)

Zhai, Fangli; Liu, Xiaojuan; Ruan, Jing; Li, Jing; Liu, Zhenlong; Hu, Yulin; Li, Shentao

2011-01-01

Phosphoribosylglycinamide formyltransferase (PurN) from Streptococcus mutans was expressed in E. coli, purified and studied crystallographically. Phosphoribosylglycinamide formyltransferase (PurN) from Streptococcus mutans was recombinantly expressed in Escherichia coli. An effective purification protocol was established. The purified protein, which had a purity of >95%, was identified by SDS–PAGE and MALDI–TOF MS. The protein was crystallized using the vapour-diffusion method in hanging-drop mode with PEG 3350 as the primary precipitant. X-ray diffraction data were collected to 2.1 Å resolution. Preliminary X-ray analysis indicated that the crystal belonged to space group P2 1 2 1 2 1 , with unit-cell parameters a = 52.25, b = 63.29, c = 131.81 Å

Time-resolved X-ray diffraction with accelerator- and laser-plasma-based X-ray sources

International Nuclear Information System (INIS)

Nicoul, Matthieu

2010-01-01

Femtosecond X-ray pulses are a powerful tool to investigate atomic motions triggered by femtosecond pump pulses. This thesis is dedicated to the production of such pulses and their use in optical pump - X-ray probe measurement. This thesis describes the laser-plasma-based sources available at the University of Duisburg-Essen. Part of it consists of the description of the design, built-up and characterization of a new ''modular'' X-ray source dedicated to optimize the X-ray flux onto the sample under investigation. The acoustic wave generation in femtosecond optically excited semiconductor (gallium arsenide) and metal (gold) was performed using the sources of the University of Duisburg-Essen. The physical answer of the material was modeled by a simple strain model for the semiconductor, pressure model for the metal, in order to gain information on the interplay of the electronic and thermal pressures rising after excitation. Whereas no reliable information could be obtain in gallium arsenide (principally due to the use of a bulk), the model for gold achieved very good agreement, providing useful information. The relaxation time of the electron to lattice energy was found to be (5.0±0.3) ps, and the ratio of the Grueneisen parameters was found to be γ e / γ i = (0.5±0.1). This thesis also describes the Sub-Picosecond Pulse Source (SPPS) which existed at the (formally) Stanford Linear Accelerator Center, an accelerator-based X-ray source, and two measurements performed with it. The first one is the detailed investigation of the phonon softening of the A 1g mode launch in bismuth upon fluence excitation. Detailed information concerning the new equilibrium position and phonon frequency were obtained over extended laser pump fluences. The second measurement concerned the study of the liquid phase dynamics in a newly formed liquid phase following ultrafast melting in indium antimonide. The formation of the liquid phase and its development for excitations close to the

Time-resolved X-ray diffraction with accelerator- and laser-plasma-based X-ray sources

Energy Technology Data Exchange (ETDEWEB)

Nicoul, Matthieu

2010-09-01

Femtosecond X-ray pulses are a powerful tool to investigate atomic motions triggered by femtosecond pump pulses. This thesis is dedicated to the production of such pulses and their use in optical pump - X-ray probe measurement. This thesis describes the laser-plasma-based sources available at the University of Duisburg-Essen. Part of it consists of the description of the design, built-up and characterization of a new ''modular'' X-ray source dedicated to optimize the X-ray flux onto the sample under investigation. The acoustic wave generation in femtosecond optically excited semiconductor (gallium arsenide) and metal (gold) was performed using the sources of the University of Duisburg-Essen. The physical answer of the material was modeled by a simple strain model for the semiconductor, pressure model for the metal, in order to gain information on the interplay of the electronic and thermal pressures rising after excitation. Whereas no reliable information could be obtain in gallium arsenide (principally due to the use of a bulk), the model for gold achieved very good agreement, providing useful information. The relaxation time of the electron to lattice energy was found to be (5.0{+-}0.3) ps, and the ratio of the Grueneisen parameters was found to be {gamma}{sub e} / {gamma}{sub i} = (0.5{+-}0.1). This thesis also describes the Sub-Picosecond Pulse Source (SPPS) which existed at the (formally) Stanford Linear Accelerator Center, an accelerator-based X-ray source, and two measurements performed with it. The first one is the detailed investigation of the phonon softening of the A{sub 1g} mode launch in bismuth upon fluence excitation. Detailed information concerning the new equilibrium position and phonon frequency were obtained over extended laser pump fluences. The second measurement concerned the study of the liquid phase dynamics in a newly formed liquid phase following ultrafast melting in indium antimonide. The formation of the liquid phase

X-ray diffraction study of KTP (KTiOPO4) crystals under a static electric field

International Nuclear Information System (INIS)

Sebastian, M.T.; Klapper, H.; Bolt, R.J.

1992-01-01

X-ray diffraction studies are made on ion-conducting potassium titanyl phosphate (KTP) crystals with in situ DC electric field along different crystallographic directions. The X-ray rocking curves recorded with an electric field along the polar b axis (which is the direction of ion conduction) show a strong enhancement of the 040 reflection intensity (reflecting planes normal to the b axis) whereas the h0l reflections (reflecting planes parallel to the polar axis) do not show any intensity change. For an electric field normal to the polar axis no intensity change, either in 040 or in h0l reflections occurs. This observation is supplemented by X-ray topography. The 040 X-ray topographs recorded with in situ electric field along b exhibit strong extinction contrast in the form of striations parallel to the polar (ion-conduction) axis. The 040 intensity increase and the striation contrast are attributed to lattice deformation by the space-charge polarization due to the movement of the K + ions under the influence of the electric field. (orig.)

Sub-atomic dimensional metrology: developments in the control of x-ray interferometers

Science.gov (United States)

Yacoot, Andrew; Kuetgens, Ulrich

2012-07-01

Within the European Metrology Research Programme funded project NANOTRACE, the nonlinearity of the next generation of optical interferometers has been measured using x-ray interferometry. The x-ray interferometer can be regarded as a ruler or translation stage whose graduations or displacement steps are based on the lattice spacing of the crystallographic planes from which the x-rays are diffracted: in this case the graduations are every 192 pm corresponding to the spacing between the (2 2 0) planes in silicon. Precise displacement of the x-ray interferometer's monolithic translation stage in steps corresponding to discrete numbers of x-ray fringes requires servo positioning capability at the picometre level. To achieve this very fine control, a digital control system has been developed which has opened up the potential for advances in metrology using x-ray interferometry that include quadrature counting of x-ray fringes.

Sub-atomic dimensional metrology: developments in the control of x-ray interferometers

International Nuclear Information System (INIS)

Yacoot, Andrew; Kuetgens, Ulrich

2012-01-01

Within the European Metrology Research Programme funded project NANOTRACE, the nonlinearity of the next generation of optical interferometers has been measured using x-ray interferometry. The x-ray interferometer can be regarded as a ruler or translation stage whose graduations or displacement steps are based on the lattice spacing of the crystallographic planes from which the x-rays are diffracted: in this case the graduations are every 192 pm corresponding to the spacing between the (2 2 0) planes in silicon. Precise displacement of the x-ray interferometer's monolithic translation stage in steps corresponding to discrete numbers of x-ray fringes requires servo positioning capability at the picometre level. To achieve this very fine control, a digital control system has been developed which has opened up the potential for advances in metrology using x-ray interferometry that include quadrature counting of x-ray fringes. (paper)

X-ray imaging of superconducting radio frequency cavities

Science.gov (United States)

Musser, Susan Elizabeth

The goal of this research was to develop an improved diagnostic technique to identify the location of defects that limit superconducting radio frequency (SRF) cavity performance during cavity testing or in existing accelerators. SRF cavities are primarily constructed of niobium. Electrons within the metal of a cavity under high electric field gradient have a probability of tunneling through the potential barrier. i e. leave the surface or are field emitted in regions where defects are encountered. Field emitted electrons are accelerated in the electric fields within the cavity. The electrons can have complicated trajectories and strike the cavity walls thus producing x-rays via Coulomb interactions and/or bremsstrahlung radiation. The endpoint energy of an x-ray spectrum predicts the electron maximum final kinetic energy within the cavity. Field emission simulations can then predict the source of the field-emitted electrons and the defect(s). In a multicell cavity the cells are coupled together and act as a set of coupled oscillators. There are multiple passbands of excitation for a multicell structure operating in a particular mode. For different passbands of operation the direction and amplitude of the fields within a cavity change from that of the normal accelerating mode. Field emitted electrons have different trajectories depending on the mode and thus produce x-rays in different locations. Using a collimated sodium iodide detector and subjecting a cavity to multiple passband modes at high electric field gradient the source of a cavity's x-rays can be determined. Knowing the location of the x-rays and the maximum electron kinetic energy; field emission simulations for different passband modes can be used to determine and verify the source of the field emitted electrons from mode to mode. Once identified, the defect(s) can be repaired or modifications made to the manufacturing process.

Aplanatic telescopes based on Schwarzschild optical configuration: from grazing incidence Wolter-like x-ray optics to Cherenkov two-mirror normal incidence telescopes

Science.gov (United States)

Sironi, Giorgia

2017-09-01

At the beginning of XX century Karl Schwarzschild defined a method to design large-field aplanatic telescopes based on the use of two aspheric mirrors. The approach was then refined by Couder (1926) who, in order to correct for the astigmatic aberration, introduced a curvature of the focal plane. By the way, the realization of normal-incidence telescopes implementing the Schwarzschild aplanatic configuration has been historically limited by the lack of technological solutions to manufacture and test aspheric mirrors. On the other hand, the Schwarzschild solution was recovered for the realization of coma-free X-ray grazing incidence optics. Wolter-like grazing incidence systems are indeed free of spherical aberration, but still suffer from coma and higher order aberrations degrading the imaging capability for off-axis sources. The application of the Schwarzschild's solution to X-ray optics allowed Wolter to define an optical system that exactly obeys the Abbe sine condition, eliminating coma completely. Therefore these systems are named Wolter-Schwarzschild telescopes and have been used to implement wide-field X-ray telescopes like the ROSAT WFC and the SOHO X-ray telescope. Starting from this approach, a new class of X-ray optical system was proposed by Burrows, Burg and Giacconi assuming polynomials numerically optimized to get a flat field of view response and applied by Conconi to the wide field x-ray telescope (WFXT) design. The Schwarzschild-Couder solution has been recently re-discovered for the application to normal-incidence Cherenkov telescopes, thanks to the suggestion by Vassiliev and collaborators. The Italian Institute for Astrophysics (INAF) realized the first Cherenkov telescope based on the polynomial variation of the Schwarzschild configuration (the so-called ASTRI telescope). Its optical qualification was successfully completed in 2016, demonstrating the suitability of the Schwarzschild-like configuration for the Cherenkov astronomy requirements

A preliminary study of breast cancer diagnosis using laboratory based small angle x-ray scattering

Science.gov (United States)

Round, A. R.; Wilkinson, S. J.; Hall, C. J.; Rogers, K. D.; Glatter, O.; Wess, T.; Ellis, I. O.

2005-09-01

Breast tissue collected from tumour samples and normal tissue from bi-lateral mastectomy procedures were examined using small angle x-ray scattering. Previous work has indicated that breast tissue disease diagnosis could be performed using small angle x-ray scattering (SAXS) from a synchrotron radiation source. The technique would be more useful to health services if it could be made to work using a conventional x-ray source. Consistent and reliable differences in x-ray scatter distributions were observed between samples from normal and tumour tissue samples using the laboratory based 'SAXSess' system. Albeit from a small number of samples, a sensitivity of 100% was obtained. This result encourages us to pursue the implementation of SAXS as a laboratory based diagnosis technique.

A preliminary study of breast cancer diagnosis using laboratory based small angle x-ray scattering

Energy Technology Data Exchange (ETDEWEB)

Round, A R [Daresbury Laboratories, Warrington, WA4 4AD (United Kingdom); Wilkinson, S J [Daresbury Laboratories, Warrington, WA4 4AD (United Kingdom); Hall, C J [Daresbury Laboratories, Warrington, WA4 4AD (United Kingdom); Rogers, K D [Department of Materials and Medical Sciences, Cranfield University, Swindon, SN6 8LA (United Kingdom); Glatter, O [Department of Chemistry, University of Graz (Austria); Wess, T [School of Optometry and Vision Sciences, Cardiff University, Cardiff CF10 3NB, Wales (United Kingdom); Ellis, I O [Nottingham City Hospital, Nottingham (United Kingdom)

2005-09-07

Breast tissue collected from tumour samples and normal tissue from bi-lateral mastectomy procedures were examined using small angle x-ray scattering. Previous work has indicated that breast tissue disease diagnosis could be performed using small angle x-ray scattering (SAXS) from a synchrotron radiation source. The technique would be more useful to health services if it could be made to work using a conventional x-ray source. Consistent and reliable differences in x-ray scatter distributions were observed between samples from normal and tumour tissue samples using the laboratory based 'SAXSess' system. Albeit from a small number of samples, a sensitivity of 100% was obtained. This result encourages us to pursue the implementation of SAXS as a laboratory based diagnosis technique.

A preliminary study of breast cancer diagnosis using laboratory based small angle x-ray scattering

International Nuclear Information System (INIS)

Round, A R; Wilkinson, S J; Hall, C J; Rogers, K D; Glatter, O; Wess, T; Ellis, I O

2005-01-01

Breast tissue collected from tumour samples and normal tissue from bi-lateral mastectomy procedures were examined using small angle x-ray scattering. Previous work has indicated that breast tissue disease diagnosis could be performed using small angle x-ray scattering (SAXS) from a synchrotron radiation source. The technique would be more useful to health services if it could be made to work using a conventional x-ray source. Consistent and reliable differences in x-ray scatter distributions were observed between samples from normal and tumour tissue samples using the laboratory based 'SAXSess' system. Albeit from a small number of samples, a sensitivity of 100% was obtained. This result encourages us to pursue the implementation of SAXS as a laboratory based diagnosis technique

Design of a microcomputer-based X-ray diffractometer controller

International Nuclear Information System (INIS)

Naval, P.C. Jr.

1988-01-01

This work describes the design of an Apple II-based X-ray diffractometer controller capable of acquiring and analyzing X-ray powder diffraction data. The controller's interrupt-drivers hardware includes an on-based scaler for counting X-ray pulses, a closed-loop stepper motor driver for Philips PW 1050 Vertical Goniometer, and circuits for present data collection and safety. ACQUIRE - data acquisition program for the controller coordinates its various devices so that it can perform sample scanning in any of the following modes: continuous, present tome or present count scanning. This program watches over the scanning process and will try to correct any error it detects. Any fault monitored is logged on disk. The collected diffraction data are stored on disk together with its data acquisition parameters and may be transported to another computer. Data analysis is done by ANALYZE a program that operates on the output file generated by ACQUIRE. Its 15 single-keystroke commands permit panning and zooming of the sample's diffractogram, data smoothing, data peak search, peak report generation, and digital plotting. Data smoothing uses a third-degree Savitzky-Golay Convoluting Filter of user defined width. For peak detection, the peak search algorithm examines the diffractograms second derivative for any Gaussian resemblance and checks the peaks' area for statistical significance. The hard copy plot is available from any on-line digital plotted supporting EPSON's Mode D Plotter Commands. (Author). 15 refs. Appendixes p. 85-163

X-ray fluorescence imaging with polycapillary X-ray optics

International Nuclear Information System (INIS)

Yonehara, Tasuku; Yamaguchi, Makoto; Tsuji, Kouichi

2010-01-01

X-ray fluorescence spectrometry imaging is a powerful tool to provide information about the chemical composition and elemental distribution of a specimen. X-ray fluorescence spectrometry images were conventionally obtained by using a μ-X-ray fluorescence spectrometry spectrometer, which requires scanning a sample. Faster X-ray fluorescence spectrometry imaging would be achieved by eliminating the process of sample scanning. Thus, we developed an X-ray fluorescence spectrometry imaging instrument without sample scanning by using polycapillary X-ray optics, which had energy filter characteristics caused by the energy dependence of the total reflection phenomenon. In the present paper, we show that two independent straight polycapillary X-ray optics could be used as an energy filter of X-rays for X-ray fluorescence. Only low energy X-rays were detected when the angle between the two optical axes was increased slightly. Energy-selective X-ray fluorescence spectrometry images with projection mode were taken by using an X-ray CCD camera equipped with two polycapillary optics. It was shown that Fe Kα (6.40 keV) and Cu Kα (8.04 keV) could be discriminated for Fe and Cu foils.

Subgroup report on hard x-ray microprobes

International Nuclear Information System (INIS)

Ice, G.E.; Barbee, T.; Bionta, R.; Howells, M.; Thompson, A.C.; Yun, W.

1994-01-01

The increasing availability of synchrotron x-ray sources has stimulated the development of advanced hard x-ray (E≥5 keV) microprobes. New x-ray optics have been demonstrated which show promise for achieving intense submicron hard x-ray probes. These probes will be used for extraordinary elemental detection by x-ray fluorescence/absorption and for microdiffraction to identify phase and strain. The inherent elemental and crystallographic sensitivity of an x-ray microprobe and its inherently nondestructive and penetrating nature makes the development of an advanced hard x-ray microprobe an important national goal. In this workshop state-of-the-art hard x-ray microprobe optics were described and future directions were discussed. Gene Ice, Oak Ridge National Laboratory (ORNL), presented an overview of the current status of hard x-ray microprobe optics and described the use of crystal spectrometers to improve minimum detectable limits in fluorescent microprobe experiments. Al Thompson, Lawrence Berkeley Laboratory (LBL), described work at the Center for X-ray Optics to develop a hard x-ray microprobe based on Kirkpatrick-Baez (KB) optics. Al Thompson also showed the results of some experimental measurements with their KB optics. Malcolm Howells presented a method for bending elliptical mirrors and Troy Barbee commented on the use of graded d spacings to achieve highest efficiency in KB multilayer microfocusing. Richard Bionta, Lawrence Livermore National Laboratory (LLNL), described the development of the first hard x-ray zone plates and future promise of so called open-quotes jelly rollclose quotes or sputter slice zone plates. Wenbing Yun, Argonne National Laboratory (ANL), described characterization of jelly roll and lithographically produced zone plates and described the application of zone plates to focus extremely narrow bandwidths by nuclear resonance. This report summarizes the presentations of the workshop subgroup on hard x-ray microprobes

Relative survival of hybrid x-ray-resistant, and normally sensitive mammalian cells exposed to x rays and protons under aerobic and hypoxic conditions

International Nuclear Information System (INIS)

Williams, J.R.; Gould, R.G.; Flynn, D.; Robertson, J.B.; Little, J.B.

1978-01-01

Survival of an x-ray-resistant hybrid cell line (HD 1 ) and a normally responsive cell line (H 4 ) have been compared when irradiated under induced hypoxia by both protons and X rays. The two cell lines are similarly protected when irradiated under hypoxic conditions with oxygen enhancement ratios of 2.8 and 2.7, respectively. The protection is consistent with a dose-modifying factor. No statistically significant difference is observed between cell inactivation by x rays and protons in either cell line, whether irradiated under aerobic or hypoxic conditions

Purification, crystallization and preliminary X-ray crystallographic analysis of the ATPase domain of human TAP in nucleotide-free and ADP-, vanadate- and azide-complexed forms

International Nuclear Information System (INIS)

Meena, Sita R.; Gangwar, Shanti P.; Saxena, Ajay K.

2012-01-01

The ATPase domain of human TAP in nucleotide free, ADP, vanadate and azide complexed forms were purified and crystallized. The X-ray diffraction data sets were collected for all crystals in the resolution range of 2.8–3.0 Å. The human transporter associated with antigen processing (TAP) protein belongs to the ATP-binding cassette (ABC) transporter superfamily and is formed by the heterodimerization of TAP1 and TAP2 subunits. TAP selectively pumps cytosolic peptides into the lumen of the endoplasmic reticulum in an ATP-dependent manner. The catalytic cycle of the ATPase domain of TAP is not understood at the molecular level. The structures of catalytic intermediates of the ATPase domain of TAP will contribute to the understanding of the chemical mechanism of ATP hydrolysis. In order to understand this mechanism, the ATPase domain of human TAP1 (NBD1) was expressed and purified, crystallized in nucleotide-free and transition-state complex forms and X-ray crystallographic studies were performed. The NBD1 protein was crystallized (i) in the nucleotide-free apo form; (ii) in complex with ADP–Mg 2+ , mimicking the product-bound state; (iii) in complex with vanadate–ADP–Mg 2+ , mimicking the ATP-bound state; and (iv) in complex with azide–ADP–Mg 2+ , also mimicking the ATP-bound state. X-ray diffraction data sets were collected for apo and complexed NBD1 using an in-house X-ray diffraction facility at a wavelength of 1.5418 Å. The apo and complexed NBD1 crystals belonged to the primitive hexagonal space group P6 2 , with one monomer in the asymmetric unit. Here, the crystallization, data collection and preliminary crystallographic analysis of apo and complexed NBD1 are reported

Cone-beam x-ray luminescence computed tomography based on x-ray absorption dosage

Science.gov (United States)

Liu, Tianshuai; Rong, Junyan; Gao, Peng; Zhang, Wenli; Liu, Wenlei; Zhang, Yuanke; Lu, Hongbing

2018-02-01

With the advances of x-ray excitable nanophosphors, x-ray luminescence computed tomography (XLCT) has become a promising hybrid imaging modality. In particular, a cone-beam XLCT (CB-XLCT) system has demonstrated its potential in in vivo imaging with the advantage of fast imaging speed over other XLCT systems. Currently, the imaging models of most XLCT systems assume that nanophosphors emit light based on the intensity distribution of x-ray within the object, not completely reflecting the nature of the x-ray excitation process. To improve the imaging quality of CB-XLCT, an imaging model that adopts an excitation model of nanophosphors based on x-ray absorption dosage is proposed in this study. To solve the ill-posed inverse problem, a reconstruction algorithm that combines the adaptive Tikhonov regularization method with the imaging model is implemented for CB-XLCT reconstruction. Numerical simulations and phantom experiments indicate that compared with the traditional forward model based on x-ray intensity, the proposed dose-based model could improve the image quality of CB-XLCT significantly in terms of target shape, localization accuracy, and image contrast. In addition, the proposed model behaves better in distinguishing closer targets, demonstrating its advantage in improving spatial resolution.

Multi-Layer Organic Squaraine-Based Photodiode for Indirect X-Ray Detection

Science.gov (United States)

Iacchetti, Antonio; Binda, Maddalena; Natali, Dario; Giussani, Mattia; Beverina, Luca; Fiorini, Carlo; Peloso, Roberta; Sampietro, Marco

2012-10-01

The paper presents an organic-based photodiode coupled to a CsI(Tl) scintillator to realize an X-ray detector. A suitable blend of an indolic squaraine derivative and of fullerene derivative has been used for the photodiode, thus allowing external quantum efficiency in excess of 10% at a wavelength of 570 nm, well matching the scintillator output spectrum. Thanks to the additional deposition of a 15 nm thin layer of a suitable low electron affinity polymer, carriers injection from the metal into the organic semiconductor has been suppressed, and dark current density as low as has been obtained, which is comparable to standard Si-based photodiodes. By using a collimated X-ray beam impinging onto the scintillator mounted over the photodiode we have been able to measure current variations in the order of 150 pA on a dark current floor of less than 50 pA when operating the X-ray tube in switching mode, thus proving the feasibility of indirect X-ray detection by means of organic semiconductors.

X-ray apparatus

International Nuclear Information System (INIS)

Sell, L.J.

1981-01-01

A diagnostic x-ray device, readily convertible between conventional radiographic and tomographic operating modes, is described. An improved drive system interconnects and drives the x-ray source and the imaging device through coordinated movements for tomography

Charge collection and absorption-limited x-ray sensitivity of pixellated x-ray detectors

International Nuclear Information System (INIS)

Kabir, M. Zahangir; Kasap, S.O.

2004-01-01

The charge collection and absorption-limited x-ray sensitivity of a direct conversion pixellated x-ray detector operating in the presence of deep trapping of charge carriers is calculated using the Shockley-Ramo theorem and the weighting potential of the individual pixel. The sensitivity of a pixellated x-ray detector is analyzed in terms of normalized parameters; (a) the normalized x-ray absorption depth (absorption depth/photoconductor thickness), (b) normalized pixel width (pixel size/thickness), and (c) normalized carrier schubwegs (schubweg/thickness). The charge collection and absorption-limited sensitivity of pixellated x-ray detectors mainly depends on the transport properties (mobility and lifetime) of the charges that move towards the pixel electrodes and the extent of dependence increases with decreasing normalized pixel width. The x-ray sensitivity of smaller pixels may be higher or lower than that of larger pixels depending on the rate of electron and hole trapping and the bias polarity. The sensitivity of pixellated detectors can be improved by ensuring that the carrier with the higher mobility-lifetime product is drifted towards the pixel electrodes

Combined optic system based on polycapillary X-ray optics and single-bounce monocapillary optics for focusing X-rays from a conventional laboratory X-ray source

Energy Technology Data Exchange (ETDEWEB)

Sun, Xuepeng; Liu, Zhiguo [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Sun, Tianxi, E-mail: stx@bnu.edu.cn [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Yi, Longtao; Sun, Weiyuan; Li, Fangzuo; Jiang, Bowen [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Ma, Yongzhong [Center for Disease Control and Prevention of Beijing, Beijing 100013 (China); Ding, Xunliang [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

2015-12-01

Two combined optic systems based on polycapillary X-ray optics and single-bounce monocapillary optics (SBMO) were designed for focusing the X-rays from a conventional laboratory X-ray source. One was based on a polycapillary focusing X-ray lens (PFXRL) and a single-bounce ellipsoidal capillary (SBEC), in which the output focal spot with the size of tens of micrometers of the PFXRL was used as the “virtual” X-ray source for the SBEC. The other system was based on a polycapillary parallel X-ray lens (PPXRL) and a single-bounce parabolic capillary (SBPC), in which the PPXRL transformed the divergent X-ray beam from an X-ray source into a quasi-parallel X-ray beam with the divergence of sever milliradians as the incident illumination of the SBPC. The experiment results showed that the combined optic systems based on PFXRL and SBEC with a Mo rotating anode X-ray generator with the focal spot with a diameter of 300 μm could obtain a focal spot with the total gain of 14,300 and focal spot size of 37.4 μm, and the combined optic systems based on PPXRL and SBPC with the same X-ray source mentioned above could acquire a focal spot with the total gain of 580 and focal spot size of 58.3 μm, respectively. The two combined optic systems have potential applications in micro X-ray diffraction, micro X-ray fluorescence, micro X-ray absorption near edge structure, full field X-ray microscopes and so on.

A Mo-anode-based in-house source for small-angle X-ray scattering measurements of biological macromolecules

Energy Technology Data Exchange (ETDEWEB)

Bruetzel, Linda K.; Fischer, Stefan; Salditt, Annalena; Sedlak, Steffen M.; Nickel, Bert; Lipfert, Jan, E-mail: Jan.Lipfert@lmu.de [Department of Physics, Nanosystems Initiative Munich, and Center for Nanoscience, Ludwig-Maximilians-University Munich, Amalienstr. 54, 80799 Munich, Germany and Geschwister-Scholl Platz 1, 80539 Munich (Germany)

2016-02-15

We demonstrate the use of a molybdenum-anode-based in-house small-angle X-ray scattering (SAXS) setup to study biological macromolecules in solution. Our system consists of a microfocus X-ray tube delivering a highly collimated flux of 2.5 × 10{sup 6} photons/s at a beam size of 1.2 × 1.2 mm{sup 2} at the collimation path exit and a maximum beam divergence of 0.16 mrad. The resulting observable scattering vectors q are in the range of 0.38 Å{sup −1} down to 0.009 Å{sup −1} in SAXS configuration and of 0.26 Å{sup −1} up to 5.7 Å{sup −1} in wide-angle X-ray scattering (WAXS) mode. To determine the capabilities of the instrument, we collected SAXS data on weakly scattering biological macromolecules including proteins and a nucleic acid sample with molecular weights varying from ∼12 to 69 kDa and concentrations of 1.5–24 mg/ml. The measured scattering data display a high signal-to-noise ratio up to q-values of ∼0.2 Å{sup −1} allowing for an accurate structural characterization of the samples. Moreover, the in-house source data are of sufficient quality to perform ab initio 3D structure reconstructions that are in excellent agreement with the available crystallographic structures. In addition, measurements for the detergent decyl-maltoside show that the setup can be used to determine the size, shape, and interactions (as characterized by the second virial coefficient) of detergent micelles. This demonstrates that the use of a Mo-anode based in-house source is sufficient to determine basic geometric parameters and 3D shapes of biomolecules and presents a viable alternative to valuable beam time at third generation synchrotron sources.

Soft X-ray images of the solar corona using normal incidence optics

Science.gov (United States)

Bruner, M. E.; Haisch, B. M.; Brown, W. A.; Acton, L. W.; Underwood, J. H.

1988-01-01

A solar coronal loop system has been photographed in soft X-rays using a normal incidence telescope based on multilayer mirror technology. The telescope consisted of a spherical objective mirror of 4 cm aperture and 1 m focal length, a film cassette, and a focal plane shutter. A metallized thin plastic film filter was used to exclude visible light. The objective mirror was covered with a multilayer coating consisting of alternating layers of tungsten and carbon whose combined thicknesses satisfied the Bragg diffraction condition for 44 A radiation. The image was recorded during a rocket flight on October 25, 1985 and was dominated by emission lines arising from the Si XII spectrum. The rocket also carried a high resolution soft X-ray spectrograph that confirmed the presence of Si XII line radiation in the source. This image represents the first successful use of multilayer technology for astrophysical observations.

A differential scanning calorimetric and X-ray diffraction

Indian Academy of Sciences (India)

X-ray diffraction analysis of the two groups demonstrated predominance of austenitic ... Discrete crystallographic structure and absence of multiple phases showed ... Division of Orthodontics, Indian Army, 10 Corps Dental Unit, C/O 56 APO, ...

A structural study of bone changes in knee osteoarthritis by synchrotron-based X-ray fluorescence and X-ray absorption spectroscopy techniques

Science.gov (United States)

Sindhupakorn, Bura; Thienpratharn, Suwittaya; Kidkhunthod, Pinit

2017-10-01

Osteoarthritis (OA) is characterized by degeneration of articular cartilage and thickening of subchondral bone. The present study investigated the changing of biochemical components of cartilage and bone compared between normal and OA people. Using Synchrotron-based X-ray fluorescence (SR-XRF) and X-ray absorption spectroscopy (XAS) techniquesincluding X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) were employed for the bone changes in kneeosteoarthritisstudies. The bone samples were collected from various osteoarthritis patients with both male and female in the ages range between 20 and 74 years old. SR-XRF results excited at 4240 eV for Ca elements show a majority three main groups, based on their XRF intensities, 20-36 years, 40-60 years and over 70 years, respectively. By employing XAS techniques, XANES features can be used to clearly explain in term of electronic transitions occurring in bone samples which are affected from osteoarthritis symptoms. Moreover, a structural change around Ca ions in bone samples is obviously obtained by EXAFS results indicating an increase of Ca-amorphous phase when the ages increase.

The Mapping X-ray Fluorescence Spectrometer (MapX)

Science.gov (United States)

Sarrazin, P.; Blake, D. F.; Marchis, F.; Bristow, T.; Thompson, K.

2017-12-01

Many planetary surface processes leave traces of their actions as features in the size range 10s to 100s of microns. The Mapping X-ray Fluorescence Spectrometer (MapX) will provide elemental imaging at 100 micron spatial resolution, yielding elemental chemistry at a scale where many relict physical, chemical, or biological features can be imaged and interpreted in ancient rocks on planetary bodies and planetesimals. MapX is an arm-based instrument positioned on a rock or regolith with touch sensors. During an analysis, an X-ray source (tube or radioisotope) bombards the sample with X-rays or alpha-particles / gamma-rays, resulting in sample X-ray Fluorescence (XRF). X-rays emitted in the direction of an X-ray sensitive CCD imager pass through a 1:1 focusing lens (X-ray micro-pore Optic (MPO)) that projects a spatially resolved image of the X-rays onto the CCD. The CCD is operated in single photon counting mode so that the energies and positions of individual X-ray photons are recorded. In a single analysis, several thousand frames are both stored and processed in real-time. Higher level data products include single-element maps with a lateral spatial resolution of 100 microns and quantitative XRF spectra from ground- or instrument- selected Regions of Interest (ROI). XRF spectra from ROI are compared with known rock and mineral compositions to extrapolate the data to rock types and putative mineralogies. When applied to airless bodies and implemented with an appropriate radioisotope source for alpha-particle excitation, MapX will be able to analyze biogenic elements C, N, O, P, S, in addition to the cations of the rock-forming elements >Na, accessible with either X-ray or gamma-ray excitation. The MapX concept has been demonstrated with a series of lab-based prototypes and is currently under refinement and TRL maturation.

Excitation of Neutron Star f-mode in Low Mass X-ray Binaries

International Nuclear Information System (INIS)

Araujo, J C N de; Miranda, O D; Aguiar, O D

2006-01-01

Neutron Stars (NSs) present a host of pulsation modes. Only a few of them, however, is of relevance from the gravitational wave (GW) point of view. Among the various possible modes the pulsation energy is mostly stored in the f-mode in which the fluid parameters undergo the largest changes. An important question is how the pulsation modes are excited in NSs. Here we consider the excitation of the f-mode in the accreting NSs belonging to Low Mass X-ray Binaries (LMXBs), which may well be a recurrent source of GWs, since the NSs are continuously receiving matter from their companion stars. We also discuss the detectability of the GWs for the scenario considered here

X-ray filter for chest x-rays

International Nuclear Information System (INIS)

Ferlic, D.J.

1984-01-01

Filter for use in medical x-ray apparatus to permit higher intensity x-ray exposure in the heart and mediastinum area while maintaining a normal level of x-ray exposure in other areas of the body, particlarly in the lung area. The filter comprises a sheet of radiation absorbing material having an opening therein, said opening corresponding to the spine and central portion of the heart. Accordingly, the upper portion of the filter exhibits a relatively narrow opening which becomes gradually wider toward the lower portion of the filter

X-ray crystallographic studies on novel natural products from marine animals

International Nuclear Information System (INIS)

Choudhary, M.I.; Clardy, J.C.

1991-01-01

This chapter starts with an analysis to illustrate the utility of X-ray diffraction. The X-ray diffraction experiment is particularly suitable for structure elucidation of naturally occurring compounds, especially those that are structurally novel or have a great deal of stereochemistry. Marine plants and animals constitute a prodigious source of new and structurally complex secondary metabolites. Their unique structural features also provide strong incentives for further structural, synthetic and biosynthetic investigations. Organic compounds isolated from various marine animals in relatively small quantities, where structural work by conventional spectroscopic techniques did not lead to ambiguous structures, are investigated and the structures were finally determined through single-crystal X-ray diffraction measurements. (A.S.) 20 refs.; 5 figs

Quantification and normalization of x-ray mammograms

International Nuclear Information System (INIS)

Tromans, Christopher E; Cocker, Mary R; Brady, Michael

2012-01-01

The analysis of (x-ray) mammograms remains qualitative, relying on the judgement of clinicians. We present a novel method to compute a quantitative, normalized measure of tissue radiodensity traversed by the primary beam incident on each pixel of a mammogram, a measure we term the standard attenuation rate (SAR). SAR enables: the estimation of breast density which is linked to cancer risk; direct comparison between images; the full potential of computer aided diagnosis to be utilized; and a basis for digital breast tomosynthesis reconstruction. It does this by removing the effects of the imaging conditions under which the mammogram is acquired. First, the x-ray spectrum incident upon the breast is calculated, and from this, the energy exiting the breast is calculated. The contribution of scattered radiation is calculated and subtracted. The SAR measure is the scaling factor that must be applied to the reference material in order to match the primary attenuation of the breast. Specifically, this is the scaled reference material attenuation which when traversed by an identical beam to that traversing the breast, and when subsequently detected, results in the primary component of the pixel intensity observed in the breast image. We present results using two tissue equivalent phantoms, as well as a sensitivity analysis to detector response changes over time and possible errors in compressed thickness measurement. (paper)

Inhibition pathways of the potent organophosphate CBDP with cholinesterases revealed by X-ray crystallographic snapshots and mass spectrometry

International Nuclear Information System (INIS)

Carletti, Eugenie; Santoni, Gianluca; Colletier, Jacques-Philippe; Schopfer, Lawrence M.; Lockridge, Oksana; Masson, Patrick; Nachon, Florian; Weik, Martin

2013-01-01

Tri-o-cresyl-phosphate (TOCP) is a common additive in jet engine lubricants and hydraulic fluids suspected to have a role in aero-toxic syndrome in humans. TOCP is metabolized to cresyl saligenin phosphate (CBDP), a potent irreversible inhibitor of butyrylcholinesterase (BChE), a natural bio-scavenger present in the bloodstream, and acetylcholinesterase (AChE), the off-switch at cholinergic synapses. Mechanistic details of cholinesterase (ChE) inhibition have, however, remained elusive. Also, the inhibition of AChE by CBDP is unexpected, from a structural standpoint, i.e., considering the narrowness of AChE active site and the bulkiness of CBDP. In the following, we report on kinetic X-ray crystallography experiments that provided 2.7-3.3 Angstroms snapshots of the reaction of CBDP with mouse AChE and human BChE. The series of crystallographic snapshots reveals that AChE and BChE react with the opposite enantiomers and that an induced-fit rearrangement of Phe297 enlarges the active site of AChE upon CBDP binding. Mass spectrometry analysis of aging in either H 2 16 O or H 2 18 O furthermore allowed us to identify the inhibition steps, in which water molecules are involved, thus providing insights into the mechanistic details of inhibition. X-ray crystallography and mass spectrometry show the formation of an aged end product formed in both AChE and BChE that cannot be reactivated by current oxime-based therapeutics. Our study thus shows that only prophylactic and symptomatic treatments are viable to counter the inhibition of AChE and BChE by CBDP. (authors)

X-CHIP: an integrated platform for high-throughput protein crystallization and on-the-chip X-ray diffraction data collection

International Nuclear Information System (INIS)

Kisselman, Gera; Qiu, Wei; Romanov, Vladimir; Thompson, Christine M.; Lam, Robert; Battaile, Kevin P.; Pai, Emil F.; Chirgadze, Nickolay Y.

2011-01-01

The X-CHIP (X-ray Crystallography High-throughput Integrated Platform) is a novel microchip that has been developed to combine multiple steps of the crystallographic pipeline from crystallization to diffraction data collection on a single device to streamline the entire process. The X-CHIP (X-ray Crystallization High-throughput Integrated Platform) is a novel microchip that has been developed to combine multiple steps of the crystallographic pipeline from crystallization to diffraction data collection on a single device to streamline the entire process. The system has been designed for crystallization condition screening, visual crystal inspection, initial X-ray screening and data collection in a high-throughput fashion. X-ray diffraction data acquisition can be performed directly on-the-chip at room temperature using an in situ approach. The capabilities of the chip eliminate the necessity for manual crystal handling and cryoprotection of crystal samples, while allowing data collection from multiple crystals in the same drop. This technology would be especially beneficial for projects with large volumes of data, such as protein-complex studies and fragment-based screening. The platform employs hydrophilic and hydrophobic concentric ring surfaces on a miniature plate transparent to visible light and X-rays to create a well defined and stable microbatch crystallization environment. The results of crystallization and data-collection experiments demonstrate that high-quality well diffracting crystals can be grown and high-resolution diffraction data sets can be collected using this technology. Furthermore, the quality of a single-wavelength anomalous dispersion data set collected with the X-CHIP at room temperature was sufficient to generate interpretable electron-density maps. This technology is highly resource-efficient owing to the use of nanolitre-scale drop volumes. It does not require any modification for most in-house and synchrotron beamline systems and offers

X-CHIP: an integrated platform for high-throughput protein crystallization and on-the-chip X-ray diffraction data collection

Energy Technology Data Exchange (ETDEWEB)

Kisselman, Gera; Qiu, Wei; Romanov, Vladimir; Thompson, Christine M.; Lam, Robert [Ontario Cancer Institute, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2C4 (Canada); Battaile, Kevin P. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Pai, Emil F.; Chirgadze, Nickolay Y., E-mail: nchirgad@uhnresearch.ca [Ontario Cancer Institute, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2C4 (Canada); University of Toronto, Toronto, Ontario M5S 1A8 (Canada)

2011-06-01

The X-CHIP (X-ray Crystallography High-throughput Integrated Platform) is a novel microchip that has been developed to combine multiple steps of the crystallographic pipeline from crystallization to diffraction data collection on a single device to streamline the entire process. The X-CHIP (X-ray Crystallization High-throughput Integrated Platform) is a novel microchip that has been developed to combine multiple steps of the crystallographic pipeline from crystallization to diffraction data collection on a single device to streamline the entire process. The system has been designed for crystallization condition screening, visual crystal inspection, initial X-ray screening and data collection in a high-throughput fashion. X-ray diffraction data acquisition can be performed directly on-the-chip at room temperature using an in situ approach. The capabilities of the chip eliminate the necessity for manual crystal handling and cryoprotection of crystal samples, while allowing data collection from multiple crystals in the same drop. This technology would be especially beneficial for projects with large volumes of data, such as protein-complex studies and fragment-based screening. The platform employs hydrophilic and hydrophobic concentric ring surfaces on a miniature plate transparent to visible light and X-rays to create a well defined and stable microbatch crystallization environment. The results of crystallization and data-collection experiments demonstrate that high-quality well diffracting crystals can be grown and high-resolution diffraction data sets can be collected using this technology. Furthermore, the quality of a single-wavelength anomalous dispersion data set collected with the X-CHIP at room temperature was sufficient to generate interpretable electron-density maps. This technology is highly resource-efficient owing to the use of nanolitre-scale drop volumes. It does not require any modification for most in-house and synchrotron beamline systems and offers

Constraining the physics of the r-mode instability in neutron stars with X-ray and ultraviolet observations

NARCIS (Netherlands)

Haskell, B.; Degenaar, N.; Ho, W.C.G.

2012-01-01

Rapidly rotating neutron stars in low-mass X-ray binaries may be an interesting source of gravitational waves (GWs). In particular, several modes of stellar oscillation may be driven unstable by GW emission, and this can lead to a detectable signal. Here we illustrate how current X-ray and

Micromanipulation and pick-up system for X-Ray diffraction characterization of micrometer-sized single particles

International Nuclear Information System (INIS)

Takeichi, Y; Inami, N; Saito, K; Otori, H; Sagayama, R; Kumai, R; Ono, K; Ueno, T

2014-01-01

We describe a micromanipulation and pick-up system for preparing a micrometer-sized single particle for X-ray diffraction characterization. Combining a microgripper based on microelectromechanical systems, piezo-motor-driven linear stages, and a gamepad, the system provides precise and intuitive handling of the object. Single-crystal X-ray diffraction measurements of Sm-Fe-N permanent magnet were performed using this system. We also describe a method to distinguish crystallographically homogeneous particles found in powder-form samples.

Diffraction peaks in x-ray spectroscopy: Friend or foe?

International Nuclear Information System (INIS)

Tissot, R.G.; Goehner, R.P.

1992-01-01

Diffraction peaks can occur as unidentifiable peaks in the energy spectrum of an x-ray spectrometric analysis. Recently, there has been increased interest in oriented polycrystalline films and epitaxial films on single crystal substrates for electronic applications. Since these materials diffract x-rays more efficiently than randomly oriented polycrystalline materials, diffraction peaks are being observed more frequently in x-ray fluorescent spectra. In addition, micro x-ray spectrometric analysis utilizes a small, intense, collimated x-ray beam that can yield well defined diffraction peaks. In some cases these diffraction peaks can occur at the same position as elemental peaks. These diffraction peaks, although a possible problem in qualitative and quantitative elemental analysis, can give very useful information about the crystallographic structure and orientation of the material being analyzed. The observed diffraction peaks are dependent on the geometry of the x-ray spectrometer, the degree of collimation and the distribution of wavelengths (energies) originating from the x-ray tube and striking the sample

Novel X-ray Communication Based XNAV Augmentation Method Using X-ray Detectors

Directory of Open Access Journals (Sweden)

Shibin Song

2015-09-01

Full Text Available The further development of X-ray pulsar-based NAVigation (XNAV is hindered by its lack of accuracy, so accuracy improvement has become a critical issue for XNAV. In this paper, an XNAV augmentation method which utilizes both pulsar observation and X-ray ranging observation for navigation filtering is proposed to deal with this issue. As a newly emerged concept, X-ray communication (XCOM shows great potential in space exploration. X-ray ranging, derived from XCOM, could achieve high accuracy in range measurement, which could provide accurate information for XNAV. For the proposed method, the measurement models of pulsar observation and range measurement observation are established, and a Kalman filtering algorithm based on the observations and orbit dynamics is proposed to estimate the position and velocity of a spacecraft. A performance comparison of the proposed method with the traditional pulsar observation method is conducted by numerical experiments. Besides, the parameters that influence the performance of the proposed method, such as the pulsar observation time, the SNR of the ranging signal, etc., are analyzed and evaluated by numerical experiments.

Nano structured materials studied by coherent X-ray diffraction

International Nuclear Information System (INIS)

Gulden, Johannes

2013-03-01

Structure determination with X-rays in crystallography is a rapidly evolving field. Crystallographic methods for structure determination are based on the assumptions about the crystallinity of the sample. It is vital to understand the structure of possible defects in the crystal, because they can influence the structure determination. All conventional methods to characterize defects require a modelling through simulated data. No direct methods exist to image the core of defects in crystals. Here a new method is proposed, which will enable to visualize the individual scatterers around and at defects in crystals. The method is based on coherent X-ray scattering. X-rays are perfectly suited since they can penetrate thick samples and buried structures can be investigated Recent developments increased the coherent flux of X-Ray sources such as synchrotrons by orders of magnitude. As a result, the use of the coherent properties of X-rays is emerging as a new aspect of X-ray science. New upcoming and operating X-ray laser sources will accelerate this trend. One new method which has the capacity to recover structural information from the coherently scattered photons is Coherent X-ray Diffraction Imaging (CXDI). The main focus of this thesis is the investigation of the structure and the dynamics of colloidal crystals. Colloidal crystals can be used as a model for atomic crystals in order to understand the growth and defect structure. Despite the large interest in these structures, many details are still unknown.Therefore, it is vital to develop new approaches to measure the core of defects in colloidal crystals. After an introduction into the basics of the field of coherent X-ray scattering, this thesis introduces a novel method, Small Angle Bragg Coherent Diffractive Imaging, (SAB-CDI). This new measurement technique which besides the relevance to colloidal crystals can be applied to a large variety of nano structured materials. To verify the experimental possibilities the

Nano structured materials studied by coherent X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Gulden, Johannes

2013-03-15

Structure determination with X-rays in crystallography is a rapidly evolving field. Crystallographic methods for structure determination are based on the assumptions about the crystallinity of the sample. It is vital to understand the structure of possible defects in the crystal, because they can influence the structure determination. All conventional methods to characterize defects require a modelling through simulated data. No direct methods exist to image the core of defects in crystals. Here a new method is proposed, which will enable to visualize the individual scatterers around and at defects in crystals. The method is based on coherent X-ray scattering. X-rays are perfectly suited since they can penetrate thick samples and buried structures can be investigated Recent developments increased the coherent flux of X-Ray sources such as synchrotrons by orders of magnitude. As a result, the use of the coherent properties of X-rays is emerging as a new aspect of X-ray science. New upcoming and operating X-ray laser sources will accelerate this trend. One new method which has the capacity to recover structural information from the coherently scattered photons is Coherent X-ray Diffraction Imaging (CXDI). The main focus of this thesis is the investigation of the structure and the dynamics of colloidal crystals. Colloidal crystals can be used as a model for atomic crystals in order to understand the growth and defect structure. Despite the large interest in these structures, many details are still unknown.Therefore, it is vital to develop new approaches to measure the core of defects in colloidal crystals. After an introduction into the basics of the field of coherent X-ray scattering, this thesis introduces a novel method, Small Angle Bragg Coherent Diffractive Imaging, (SAB-CDI). This new measurement technique which besides the relevance to colloidal crystals can be applied to a large variety of nano structured materials. To verify the experimental possibilities the

Legal directives in the X-ray regulation for the field of X-ray diagnostics

International Nuclear Information System (INIS)

Huhn, Walter

2012-01-01

The operation of each X-ray device is subject to the requirements of the X-ray regulations (RoeV); for different operational modes or applications like curative diagnostics, X-ray serial examinations, X-ray radiotherapy and teleradiology different directives exist and have to be respected. The report discusses the issues licensing and notification procedures, radiation protection representative, requirements for the commissioning (teleradiology, serial X.ray examinations), technical qualification and radiation protection knowledge of physicians, technical qualification of the assistant personnel.

The phase problem and perspectives of surface X-ray diffraction

International Nuclear Information System (INIS)

Tajiri, Hiroo; Takahashi, Toshio

2009-01-01

The emergence of synchrotron radiation sources has accelerated the application of diffraction techniques to surface sciences. Surface X-ray diffraction has become the state-of-the-art technique for determining ordered structures of atoms on crystal surfaces. We introduce surface X-ray diffraction briefly from the historical point of view and describe the concept that not only determine constellation of surface atoms but also view surface atoms as image. The progress in experimental and theoretical studies of surface X-ray diffraction including crystallographic direct methods is reviewed. (author)

Characterization of LiF-based soft X-ray imaging detectors by confocal fluorescence microscopy

International Nuclear Information System (INIS)

Bonfigli, F; Gaudio, P; Lupelli, I; Nichelatti, E; Richetta, M; Vincenti, M A; Montereali, R M

2010-01-01

X-ray microscopy represents a powerful tool to obtain images of samples with very high spatial resolution. The main limitation of this technique is represented by the poor spatial resolution of standard imaging detectors. We proposed an innovative high-performance X-ray imaging detector based on the visible photoluminescence of colour centres in lithium fluoride. In this work, a confocal microscope in fluorescence mode was used to characterize LiF-based imaging detectors measuring CC integrated visible fluorescence signals of LiF crystals and films (grown on several kinds of substrates) irradiated by soft X-rays produced by a laser plasma source in different exposure conditions. The results are compared with the CC photoluminescence spectra measured on the same samples and discussed.

Cone Beam X-ray Luminescence Computed Tomography Based on Bayesian Method.

Science.gov (United States)

Zhang, Guanglei; Liu, Fei; Liu, Jie; Luo, Jianwen; Xie, Yaoqin; Bai, Jing; Xing, Lei

2017-01-01

X-ray luminescence computed tomography (XLCT), which aims to achieve molecular and functional imaging by X-rays, has recently been proposed as a new imaging modality. Combining the principles of X-ray excitation of luminescence-based probes and optical signal detection, XLCT naturally fuses functional and anatomical images and provides complementary information for a wide range of applications in biomedical research. In order to improve the data acquisition efficiency of previously developed narrow-beam XLCT, a cone beam XLCT (CB-XLCT) mode is adopted here to take advantage of the useful geometric features of cone beam excitation. Practically, a major hurdle in using cone beam X-ray for XLCT is that the inverse problem here is seriously ill-conditioned, hindering us to achieve good image quality. In this paper, we propose a novel Bayesian method to tackle the bottleneck in CB-XLCT reconstruction. The method utilizes a local regularization strategy based on Gaussian Markov random field to mitigate the ill-conditioness of CB-XLCT. An alternating optimization scheme is then used to automatically calculate all the unknown hyperparameters while an iterative coordinate descent algorithm is adopted to reconstruct the image with a voxel-based closed-form solution. Results of numerical simulations and mouse experiments show that the self-adaptive Bayesian method significantly improves the CB-XLCT image quality as compared with conventional methods.

Short-wavelength soft-x-ray laser pumped in double-pulse single-beam non-normal incidence

International Nuclear Information System (INIS)

Zimmer, D.; Ros, D.; Guilbaud, O.; Habib, J.; Kazamias, S.; Zielbauer, B.; Bagnoud, V.; Ecker, B.; Aurand, B.; Kuehl, T.; Hochhaus, D. C.; Neumayer, P.

2010-01-01

We demonstrated a 7.36 nm Ni-like samarium soft-x-ray laser, pumped by 36 J of a neodymium:glass chirped-pulse amplification laser. Double-pulse single-beam non-normal-incidence pumping was applied for efficient soft-x-ray laser generation. In this case, the applied technique included a single-optic focusing geometry for large beam diameters, a single-pass grating compressor, traveling-wave tuning capability, and an optimized high-energy laser double pulse. This scheme has the potential for even shorter-wavelength soft-x-ray laser pumping.

Synchrotron measurement of the 3D shape of X-ray reflections from the {gamma}/{gamma}{sup '}-microstructure of nickel-base superalloys

Energy Technology Data Exchange (ETDEWEB)

Epishin, Alexander; Link, Thomas; Ulbricht, Alexander; Bansal, Mamta [Technical Univ. of Berlin (Germany). Inst. of Material Science and Technology; Zizak, Ivo [Helmholtz-Zentrum Berlin for Materials and Energy BESSY II, Berlin (Germany)

2011-12-15

The 3D shape of X-ray reflections from the {gamma}/{gamma}{sup '}-microstructure of a nickel-base superalloy was investigated using synchrotron X-ray radiation and a position sensitive area detector. The measurements were performed on the 4{sup th} generation single-crystal nickel-base superalloy TMS138. The results show that X-ray reflections from non-cubic crystallographic planes have a complex 3D shape which changes during rafting. The 3D intensity distributions contain information about the spacing of the planes and their orientation as well. Whereas h00 reflections show the usual splitting into a {gamma}{sup '} and one {gamma}-subreflection, the hh0 and hhh reflections show two and three {gamma}-peaks respectively, resulting from the different types of {l_brace}100{r_brace} matrix channels. Therefore, these 3D diffraction measurements supply additional information about the spatial distribution of microstrains. (orig.)

X-ray analysis of 2-aniline benzo(2,3-)

Indian Academy of Sciences (India)

dione has been determined by X-ray crystallographic techniques. This compound crystallizes in the orthorhombic space group 212121 with unit cell parameters: = 5.467(1), = 10.657(3), = 19.602(6) Å; = 1142.01(5) Å3, = 4.

Numerical modeling of the sensitivity of x-ray driven implosions to low-mode flux asymmetries.

Science.gov (United States)

Scott, R H H; Clark, D S; Bradley, D K; Callahan, D A; Edwards, M J; Haan, S W; Jones, O S; Spears, B K; Marinak, M M; Town, R P J; Norreys, P A; Suter, L J

2013-02-15

The sensitivity of inertial confinement fusion implosions, of the type performed on the National Ignition Facility (NIF) [1], to low-mode flux asymmetries is investigated numerically. It is shown that large-amplitude, low-order mode shapes (Legendre polynomial P(4), resulting from low-order flux asymmetries, cause spatial variations in capsule and fuel momentum that prevent the deuterium and tritium (DT) "ice" layer from being decelerated uniformly by the hot spot pressure. This reduces the transfer of implosion kinetic energy to internal energy of the central hot spot, thus reducing the neutron yield. Furthermore, synthetic gated x-ray images of the hot spot self-emission indicate that P(4) shapes may be unquantifiable for DT layered capsules. Instead the positive P(4) asymmetry "aliases" itself as an oblate P(2) in the x-ray images. Correction of this apparent P(2) distortion can further distort the implosion while creating a round x-ray image. Long wavelength asymmetries may be playing a significant role in the observed yield reduction of NIF DT implosions relative to detailed postshot two-dimensional simulations.

CANDELS/GOODS-S, CDFS, and ECDFS: photometric redshifts for normal and X-ray-detected galaxies

Energy Technology Data Exchange (ETDEWEB)

Hsu, Li-Ting; Salvato, Mara; Nandra, Kirpal; Brusa, Marcella; Bender, Ralf; Buchner, Johannes; Brightman, Murray; Georgakakis, Antonis [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Donley, Jennifer L. [Los Alamos National Laboratory, Los Alamos, NM (United States); Kocevski, Dale D. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Guo, Yicheng; Barro, Guillermo; Faber, Sandra M. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA (United States); Hathi, Nimish P. [Aix Marseille Université, CNRS, LAM (Laboratoire d' Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France); Rangel, Cyprian [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Willner, S. P.; Ashby, Matthew L. N. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Budavári, Tamás; Szalay, Alexander S. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD (United States); Dahlen, Tomas [Space Telescope Science Institute, Baltimore, MD (United States); and others

2014-11-20

We present photometric redshifts and associated probability distributions for all detected sources in the Extended Chandra Deep Field South (ECDFS). This work makes use of the most up-to-date data from the Cosmic Assembly Near-IR Deep Legacy Survey (CANDELS) and the Taiwan ECDFS Near-Infrared Survey (TENIS) in addition to other data. We also revisit multi-wavelength counterparts for published X-ray sources from the 4 Ms CDFS and 250 ks ECDFS surveys, finding reliable counterparts for 1207 out of 1259 sources (∼96%). Data used for photometric redshifts include intermediate-band photometry deblended using the TFIT method, which is used for the first time in this work. Photometric redshifts for X-ray source counterparts are based on a new library of active galactic nuclei/galaxy hybrid templates appropriate for the faint X-ray population in the CDFS. Photometric redshift accuracy for normal galaxies is 0.010 and for X-ray sources is 0.014 and outlier fractions are 4% and 5.2%, respectively. The results within the CANDELS coverage area are even better, as demonstrated both by spectroscopic comparison and by galaxy-pair statistics. Intermediate-band photometry, even if shallow, is valuable when combined with deep broadband photometry. For best accuracy, templates must include emission lines.

CANDELS/GOODS-S, CDFS, and ECDFS: photometric redshifts for normal and X-ray-detected galaxies

International Nuclear Information System (INIS)

Hsu, Li-Ting; Salvato, Mara; Nandra, Kirpal; Brusa, Marcella; Bender, Ralf; Buchner, Johannes; Brightman, Murray; Georgakakis, Antonis; Donley, Jennifer L.; Kocevski, Dale D.; Guo, Yicheng; Barro, Guillermo; Faber, Sandra M.; Hathi, Nimish P.; Rangel, Cyprian; Willner, S. P.; Ashby, Matthew L. N.; Budavári, Tamás; Szalay, Alexander S.; Dahlen, Tomas

2014-01-01

We present photometric redshifts and associated probability distributions for all detected sources in the Extended Chandra Deep Field South (ECDFS). This work makes use of the most up-to-date data from the Cosmic Assembly Near-IR Deep Legacy Survey (CANDELS) and the Taiwan ECDFS Near-Infrared Survey (TENIS) in addition to other data. We also revisit multi-wavelength counterparts for published X-ray sources from the 4 Ms CDFS and 250 ks ECDFS surveys, finding reliable counterparts for 1207 out of 1259 sources (∼96%). Data used for photometric redshifts include intermediate-band photometry deblended using the TFIT method, which is used for the first time in this work. Photometric redshifts for X-ray source counterparts are based on a new library of active galactic nuclei/galaxy hybrid templates appropriate for the faint X-ray population in the CDFS. Photometric redshift accuracy for normal galaxies is 0.010 and for X-ray sources is 0.014 and outlier fractions are 4% and 5.2%, respectively. The results within the CANDELS coverage area are even better, as demonstrated both by spectroscopic comparison and by galaxy-pair statistics. Intermediate-band photometry, even if shallow, is valuable when combined with deep broadband photometry. For best accuracy, templates must include emission lines.

X-ray apparatus

International Nuclear Information System (INIS)

Bernstein, S.; Stagg, L.; Lambert, T.W.; Griswa, P.J.

1976-01-01

A patient support system for X-ray equipment in arteriographic studies of the heart is described in detail. The support system has been designed to overcome many of the practical problems encountered in using previous types of arteriographic X-ray equipment. The support system is capable of horizontal movement and, by a series of shafts attached to the main support system, the X-ray source and image intensifier or detector may be rotated through the same angle. The system is highly flexible and details are given of several possible operational modes. (U.K.)

Synthesis, X-ray crystallography, thermal studies, spectroscopic and electrochemistry investigations of uranyl Schiff base complexes.

Science.gov (United States)

Asadi, Zahra; Shorkaei, Mohammad Ranjkesh

2013-03-15

Some tetradentate salen type Schiff bases and their uranyl complexes were synthesized and characterized by UV-Vis, NMR, IR, TG, C.H.N. and X-ray crystallographic studies. From these investigations it is confirmed that a solvent molecule occupied the fifth position of the equatorial plane of the distorted pentagonal bipyramidal structure. Also, the kinetics of complex decomposition by using thermo gravimetric methods (TG) was studied. The thermal decomposition reactions are first order for the studied complexes. To examine the properties of uranyl complexes according to the substitutional groups, we have carried out the electrochemical studies. The electrochemical reactions of uranyl Schiff base complexes in acetonitrile were reversible. Copyright © 2012 Elsevier B.V. All rights reserved.

X-ray diffraction investigation of self-annealing in nanocrystalline copper electrodeposits

DEFF Research Database (Denmark)

Pantleon, Karen; Somers, Marcel A. J.

2006-01-01

X-ray diffraction analysis and electrical resistivity measurements were conducted simultaneously for in-situ examination of self-annealing in copper electrodeposits. Considerable growth of the as-deposited nano-sized crystallites occurs with time and the crystallographic texture changes by multip...... twinning during self-annealing. The kinetics of self-annealing depends on the layer thickness as well as on the orientation and/or the size of the as-deposited crystallites. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.......X-ray diffraction analysis and electrical resistivity measurements were conducted simultaneously for in-situ examination of self-annealing in copper electrodeposits. Considerable growth of the as-deposited nano-sized crystallites occurs with time and the crystallographic texture changes by multiple...

Preliminary neutron and X-ray crystallographic studies of equine cyanomethemoglobin

International Nuclear Information System (INIS)

Kovalevsky, A. Y.; Fisher, S. Zoe; Seaver, Sean; Mustyakimov, Marat; Sukumar, Narayanasami; Langan, Paul; Mueser, Timothy C.; Hanson, B. Leif

2010-01-01

Equine cyanomethemoglobin has been crystallized and X-ray and neutron diffraction data have been measured. Joint X-ray–neutron refinement is under way; the structural results should help to elucidate the differences between the hemoglobin R and T states. Room-temperature and 100 K X-ray and room-temperature neutron diffraction data have been measured from equine cyanomethemoglobin to 1.7 Å resolution using a home source, to 1.6 Å resolution on NE-CAT at the Advanced Photon Source and to 2.0 Å resolution on the PCS at Los Alamos Neutron Science Center, respectively. The cyanomethemoglobin is in the R state and preliminary room-temperature electron and neutron scattering density maps clearly show the protonation states of potential Bohr groups. Interestingly, a water molecule that is in the vicinity of the heme group and coordinated to the distal histidine appears to be expelled from this site in the low-temperature structure

Improving Beamline X-ray Optics by Analyzing the Damage to Crystallographic Structure

Energy Technology Data Exchange (ETDEWEB)

Zientek, John; Maj, Jozef; Navrotski, Gary; Srajer, George; Harmata, Charles; Maj, Lech; Lazarski, Krzysztof; Mikula, Stanislaw

2015-01-02

The mission of the X-ray Characterization Laboratory in the X-ray Science Division (XSD) at the Advanced Photon Source (APS) is to support both the users and the Optics Fabrication Facility that produces high performance optics for synchrotron X-ray beamlines. The Topography Test Unit (TTU) in the X-ray Lab has been successfully used to characterize diffracting crystals and test monochromators by quantifying residual surface stresses. This topographic method has also been adapted for testing standard X-ray mirrors, characterizing concave crystal optics and in principle, can be used to visualize residual stresses on any optic made from single crystalline material. The TTU has been instrumental in quantitatively determining crystal mounting stresses which are mechanically induced by positioning, holding, and cooling fixtures. It is this quantitative aspect that makes topography so useful since the requirements and responses for crystal optics and X-ray mirrors are quite different. In the case of monochromator crystals, even small residual or induced stresses, on the order of tens of kPa, can cause detrimental distortions to the perfect crystal rocking curves. Mirrors, on the other hand, are much less sensitive to induced stresses where stresses that are an order of magnitude greater can be tolerated. This is due to the fact that the surface rather than the lattice-spacing determines a mirror’s performance. For the highly sensitive crystal optics, it is essential to measure the in-situ rocking curves using topographs as mounting fixtures are adjusted. In this way, high heat-load monochromator crystals can be successfully mounted with minimum stress. Topographical analysis has been shown to be a highly effective method to visualize and quantify the distribution of stresses, to help identify methods that mitigate stresses, and most notably to improve diffractive crystal optic rocking curves.

The effect of caffeine on X-ray-induced mitotic delay in normal human and ataxia-telangiectasia fibroblasts

International Nuclear Information System (INIS)

Zampetti-Bosseler, F.; Scott, D.

1985-01-01

The authors previously showed that radiation-sensitive fibroblasts from ataxia-telangiectasia (A-T) patients sustain less G 2 delay after X-irradiation than normal fibroblasts. Caffeine is known to reduce the amount of X-ray-induced delay in various mammalian cell types. It is proposed that A-T cells have an altered chromatin structure, similar to that of caffeine-treated normal cells and that this results in a failure of A-T cells to delay their progression through the cell cycle to allow time for DNA repair. The authors now show that caffeine treatment after X-irradiation reduces G 2 delay in both A-T and normal cells. The authors confirm the results previously obtained on lymphocytes that caffeine potentiates the chromosome-damaging effects of X-rays in both A-T and normal fibroblasts. These and other data suggest that the radiation responses of A-T cells and of caffeine-treated normal cells are caused by different mechanisms. (Auth.)

Magnetic x-ray dichroism in ultrathin epitaxial films

Energy Technology Data Exchange (ETDEWEB)

Tobin, J.G.; Goodman, K.W. [Lawrence Berkeley National Lab., CA (United States); Cummins, T.R. [Univ. of Missouri, Rolla, MO (United States)] [and others

1997-04-01

The authors have used Magnetic X-ray Linear Dichroism (MXLD) and Magnetic X-ray Circular Dichroism (MXCD) to study the magnetic properties of epitaxial overlayers in an elementally specific fashion. Both MXLD and MXCD Photoelectron Spectroscopy were performed in a high resolution mode at the Spectromicroscopy Facility of the ALS. Circular Polarization was obtained via the utilization of a novel phase retarder (soft x-ray quarter wave plate) based upon transmission through a multilayer film. The samples were low temperature Fe overlayers, magnetic alloy films of NiFe and CoNi, and Gd grown on Y. The authors results include a direct comparison of high resolution angle resolved Photoelectron Spectroscopy performed in MXLD and MXCD modes as well as structural studies with photoelectron diffraction.

Magnetic x-ray dichroism in ultrathin epitaxial films

International Nuclear Information System (INIS)

Tobin, J.G.; Goodman, K.W.; Cummins, T.R.

1997-01-01

The authors have used Magnetic X-ray Linear Dichroism (MXLD) and Magnetic X-ray Circular Dichroism (MXCD) to study the magnetic properties of epitaxial overlayers in an elementally specific fashion. Both MXLD and MXCD Photoelectron Spectroscopy were performed in a high resolution mode at the Spectromicroscopy Facility of the ALS. Circular Polarization was obtained via the utilization of a novel phase retarder (soft x-ray quarter wave plate) based upon transmission through a multilayer film. The samples were low temperature Fe overlayers, magnetic alloy films of NiFe and CoNi, and Gd grown on Y. The authors results include a direct comparison of high resolution angle resolved Photoelectron Spectroscopy performed in MXLD and MXCD modes as well as structural studies with photoelectron diffraction

Comparison of sensitivities and detection limits between direct excitation and secondary excitation modes in energy dispersive x-ray fluorescence analysis

International Nuclear Information System (INIS)

Artz, B.E.; Short, M.A.

1976-01-01

A comparison was made between the direct tube excitation mode and the secondary target excitation mode using a Kevex 0810 energy dispersive x-ray fluorescence system. Relative sensitivities and detection limits were determined with two system configurations. The first configuration used a standard, high power, x-ray fluorescence tube to directly excite the specimen. Several x-ray tubes, including chromium, molybdenum, and tungsten, both filtered and not filtered, were employed. The second configuration consisted of using the x-ray tube to excite a secondary target which in turn excited the specimen. Appropriate targets were compared to the direct excitation results. Relative sensitivities and detection limits were determined for K-series lines for elements from magnesium to barium contained in a low atomic number matrix and in a high atomic number matrix

Cloning, expression, purification, crystallization and preliminary X-ray crystallographic analysis of the mannose 6-phosphate isomerase from Salmonella typhimurium

Energy Technology Data Exchange (ETDEWEB)

Gowda, Giri; Sagurthi, Someswar Rao [Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012 (India); Savithri, H. S. [Department of Biochemistry, Indian Institute of Science, Bangalore 560 012 (India); Murthy, M. R. N., E-mail: mrn@mbu.iisc.ernet.in [Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012 (India)

2008-02-01

The cloning, expression, purification, crystallization and preliminary X-ray crystallographic studies of mannose 6-phosphate isomerase from S. typhimurium are reported. Mannose 6-phosphate isomerase (MPI; EC 5.3.1.8) catalyzes the reversible isomerization of d-mannose 6-phosphate (M6P) and d-fructose 6-phosphate (F6P). In the eukaryotes and prokaryotes investigated to date, the enzyme has been reported to play a crucial role in d-mannose metabolism and supply of the activated mannose donor guanosine diphosphate d-mannose (GDP-d-mannose). In the present study, MPI was cloned from Salmonella typhimurium, overexpressed in Escherichia coli and purified using Ni–NTA affinity column chromatography. Purified MPI crystallized in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 36.03, b = 92.2, c = 111.01 Å. A data set extending to 1.66 Å resolution was collected with 98.8% completeness using an image-plate detector system mounted on a rotating-anode X-ray generator. The asymmetric unit of the crystal cell was compatible with the presence of a monomer of MPI. A preliminary structure solution of the enzyme has been obtained by molecular replacement using Candida albicans MPI as the phasing model and the program Phaser. Further refinement and model building are in progress.

Development of X-ray detector based on phototransistor

International Nuclear Information System (INIS)

Ramacos Fardela; Kusminarto

2014-01-01

X-ray interaction with matter can produce phenomenon of fluorescence that emits visible light. This phenomenon has been exploited to design an X-ray detector based on photo transistor by attaching a screen ZnS(Ag) on the surface of the photo transistor which is arranged in a Darlington circuit. Response of detector was done by collimating of X-rays beam from the X-ray generator tube Philips 2000 watts, 60 kV type PW 2215/20 NR 780 026 and measure the detector output voltage (V out ). Varying the current by 5, 10, 15, 20, 25, 30, 35 and 40 mA in the X-ray panel. The experimental results showed that the Darlington circuit can be applied to design the detector of X-ray based on phototransistor. The results show that there is a linear relationship between the change in the intensity of X-ray detectors with voltage output phototransistor when it was closed with fluorescence materials ZnS(Ag), the linearity coefficient was R 2 = 0.99. Sensitivity of detector was obtained to be 3.7 x 10 -2 mV per cpm. (author)

High pressure X-ray studies

International Nuclear Information System (INIS)

Sikka, S.K.

1981-01-01

High pressure research has already led to new insights in the physical properties of materials and at times to the synthesis of new ones. In all this, X-ray diffraction has been a valuable diagnostic experimental tool. In particular, X-rays in high pressure field have been used (a) for crystallographic identification of high pressure polymorphs and (b) for study of the effect of pressure on lattice parameters and volume under isothermal conditions. The results in the area (a) are reviewed. The techniques of applying high pressures are described. These include both static and dynamic shockwave X-ray apparatus. To illustrate the effect of pressure, some of the pressure induced phase transitions in pure metals are described. It has been found that there is a clear trend for elements in any group of the periodic table to adopt similar structures at high pressures. These studies have enabled to construct generalized phase diagrams for many groups. In the case of alloys, the high pressure work done on Ti-V alloys is presented. (author)

X-ray spectroscopy with normal and exotic atoms

International Nuclear Information System (INIS)

Qureshi, I.E.

1995-01-01

X-ray spectroscopy is a powerful analytical tool for elemental analysis and also for the study of nuclear properties. In recent years these has been extensive utilization of x-ray spectral analysis for the purpose of plasma diagnostics. These studies are vital for the development of controlled nuclear fusion technology. The formation of special atoms containing particles heavier than electrons is another area in which x-ray spectra give detailed knowledge of the sizes and shapes of atomic nuclei, masses and magnetic momenta of bound particles and the nature of interaction between bound particle and the nucleus. All these aspects make x-ray spectra of uniquely rich source of information on material and nuclear properties. The present article provides some glimpses of how this information is extracted. The choice of topics is biased towards nuclear physics. The presentation is not attempted to the exhaustive and is aimed at conveying the essential physical ideas without going into technical details. (author) 6 figs

Spherical grating based x-ray Talbot interferometry

Energy Technology Data Exchange (ETDEWEB)

Cong, Wenxiang, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu; Xi, Yan, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu; Wang, Ge, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu [Biomedical Imaging Center, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2015-11-15

Purpose: Grating interferometry is a state-of-the-art x-ray imaging approach, which can acquire information on x-ray attenuation, phase shift, and small-angle scattering simultaneously. Phase-contrast imaging and dark-field imaging are very sensitive to microstructural variation and offers superior contrast resolution for biological soft tissues. However, a common x-ray tube is a point-like source. As a result, the popular planar grating imaging configuration seriously restricts the flux of photons and decreases the visibility of signals, yielding a limited field of view. The purpose of this study is to extend the planar x-ray grating imaging theory and methods to a spherical grating scheme for a wider range of preclinical and clinical applications. Methods: A spherical grating matches the wave front of a point x-ray source very well, allowing the perpendicular incidence of x-rays on the grating to achieve a higher visibility over a larger field of view than the planer grating counterpart. A theoretical analysis of the Talbot effect for spherical grating imaging is proposed to establish a basic foundation for x-ray spherical gratings interferometry. An efficient method of spherical grating imaging is also presented to extract attenuation, differential phase, and dark-field images in the x-ray spherical grating interferometer. Results: Talbot self-imaging with spherical gratings is analyzed based on the Rayleigh–Sommerfeld diffraction formula, featuring a periodic angular distribution in a polar coordinate system. The Talbot distance is derived to reveal the Talbot self-imaging pattern. Numerical simulation results show the self-imaging phenomenon of a spherical grating interferometer, which is in agreement with the theoretical prediction. Conclusions: X-ray Talbot interferometry with spherical gratings has a significant practical promise. Relative to planar grating imaging, spherical grating based x-ray Talbot interferometry has a larger field of view and

Spherical grating based x-ray Talbot interferometry

International Nuclear Information System (INIS)

Cong, Wenxiang; Xi, Yan; Wang, Ge

2015-01-01

Purpose: Grating interferometry is a state-of-the-art x-ray imaging approach, which can acquire information on x-ray attenuation, phase shift, and small-angle scattering simultaneously. Phase-contrast imaging and dark-field imaging are very sensitive to microstructural variation and offers superior contrast resolution for biological soft tissues. However, a common x-ray tube is a point-like source. As a result, the popular planar grating imaging configuration seriously restricts the flux of photons and decreases the visibility of signals, yielding a limited field of view. The purpose of this study is to extend the planar x-ray grating imaging theory and methods to a spherical grating scheme for a wider range of preclinical and clinical applications. Methods: A spherical grating matches the wave front of a point x-ray source very well, allowing the perpendicular incidence of x-rays on the grating to achieve a higher visibility over a larger field of view than the planer grating counterpart. A theoretical analysis of the Talbot effect for spherical grating imaging is proposed to establish a basic foundation for x-ray spherical gratings interferometry. An efficient method of spherical grating imaging is also presented to extract attenuation, differential phase, and dark-field images in the x-ray spherical grating interferometer. Results: Talbot self-imaging with spherical gratings is analyzed based on the Rayleigh–Sommerfeld diffraction formula, featuring a periodic angular distribution in a polar coordinate system. The Talbot distance is derived to reveal the Talbot self-imaging pattern. Numerical simulation results show the self-imaging phenomenon of a spherical grating interferometer, which is in agreement with the theoretical prediction. Conclusions: X-ray Talbot interferometry with spherical gratings has a significant practical promise. Relative to planar grating imaging, spherical grating based x-ray Talbot interferometry has a larger field of view and

X-ray pulse wavefront metrology using speckle tracking

International Nuclear Information System (INIS)

Berujon, Sebastien; Ziegler, Eric; Cloetens, Peter

2015-01-01

The theoretical description and experimental implementation of a speckle-tracking-based instrument which permits the characterisation of X-ray pulse wavefronts. An instrument allowing the quantitative analysis of X-ray pulsed wavefronts is presented and its processing method explained. The system relies on the X-ray speckle tracking principle to accurately measure the phase gradient of the X-ray beam from which beam optical aberrations can be deduced. The key component of this instrument, a semi-transparent scintillator emitting visible light while transmitting X-rays, allows simultaneous recording of two speckle images at two different propagation distances from the X-ray source. The speckle tracking procedure for a reference-less metrology mode is described with a detailed account on the advanced processing schemes used. A method to characterize and compensate for the imaging detector distortion, whose principle is also based on speckle, is included. The presented instrument is expected to find interest at synchrotrons and at the new X-ray free-electron laser sources under development worldwide where successful exploitation of beams relies on the availability of an accurate wavefront metrology

Three-Dimensional X-Ray Diffraction Technique for Metals Science

DEFF Research Database (Denmark)

Zhang, Yubin; Fan, Guohua

2017-01-01

The three-dimensional X-ray diffraction (3DXRD) is a new, advanced technique for materials characterization. This technique utilizes high-energy synchrotron X-rays to characterize the 3D crystallographic structure and strain/stress state of bulk materials. As the measurement is non......-destructive, the microstructural evolution as a function of time can be followed, i.e. it allows 4D (x, y, z characterizations, t). The high brilliance of synchrotron X-rays ensures that diffraction signals from volumes of micrometer scale can be quickly detected and distinguished from the background noise, i.e. its spatial...... implemented in several large synchrotron facilities, e.g. the Advanced Photon Source (APS) in USA and the Spring-8 in Japan. Another family of 3DXRD technique that utilizes white beam synchrotron X-rays has also been developed in parallel in cooperation between Oak Ridge National Laboratory and APS...

Simultaneous use of solution NMR and X-ray data in REFMAC5 for joint refinement/detection of structural differences

Energy Technology Data Exchange (ETDEWEB)

Rinaldelli, Mauro; Ravera, Enrico; Calderone, Vito; Parigi, Giacomo [University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino (Finland) (Italy); University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino (Finland) (Italy); Murshudov, Garib N., E-mail: garib@mrc-lmb.cam.ac.uk [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH (United Kingdom); Luchinat, Claudio, E-mail: garib@mrc-lmb.cam.ac.uk [University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino (Finland) (Italy); University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino (Finland) (Italy)

2014-04-01

Paramagnetic NMR data (pseudocontact shifts and self-orientation residual dipolar couplings) and diamagnetic residual dipolar couplings can now be used in the program REFMAC5 from CCP4 as structural restraints together with X-ray crystallographic data. These NMR restraints can reveal differences between solid state and solution conformations of molecules or, in their absence, can be used together with X-ray crystallographic data for structural refinement. The program REFMAC5 from CCP4 was modified to allow the simultaneous use of X-ray crystallographic data and paramagnetic NMR data (pseudocontact shifts and self-orientation residual dipolar couplings) and/or diamagnetic residual dipolar couplings. Incorporation of these long-range NMR restraints in REFMAC5 can reveal differences between solid-state and solution conformations of molecules or, in their absence, can be used together with X-ray crystallographic data for structural refinement. Since NMR and X-ray data are complementary, when a single structure is consistent with both sets of data and still maintains reasonably ‘ideal’ geometries, the reliability of the derived atomic model is expected to increase. The program was tested on five different proteins: the catalytic domain of matrix metalloproteinase 1, GB3, ubiquitin, free calmodulin and calmodulin complexed with a peptide. In some cases the joint refinement produced a single model consistent with both sets of observations, while in other cases it indicated, outside the experimental uncertainty, the presence of different protein conformations in solution and in the solid state.

Simultaneous use of solution NMR and X-ray data in REFMAC5 for joint refinement/detection of structural differences

International Nuclear Information System (INIS)

Rinaldelli, Mauro; Ravera, Enrico; Calderone, Vito; Parigi, Giacomo; Murshudov, Garib N.; Luchinat, Claudio

2014-01-01

Paramagnetic NMR data (pseudocontact shifts and self-orientation residual dipolar couplings) and diamagnetic residual dipolar couplings can now be used in the program REFMAC5 from CCP4 as structural restraints together with X-ray crystallographic data. These NMR restraints can reveal differences between solid state and solution conformations of molecules or, in their absence, can be used together with X-ray crystallographic data for structural refinement. The program REFMAC5 from CCP4 was modified to allow the simultaneous use of X-ray crystallographic data and paramagnetic NMR data (pseudocontact shifts and self-orientation residual dipolar couplings) and/or diamagnetic residual dipolar couplings. Incorporation of these long-range NMR restraints in REFMAC5 can reveal differences between solid-state and solution conformations of molecules or, in their absence, can be used together with X-ray crystallographic data for structural refinement. Since NMR and X-ray data are complementary, when a single structure is consistent with both sets of data and still maintains reasonably ‘ideal’ geometries, the reliability of the derived atomic model is expected to increase. The program was tested on five different proteins: the catalytic domain of matrix metalloproteinase 1, GB3, ubiquitin, free calmodulin and calmodulin complexed with a peptide. In some cases the joint refinement produced a single model consistent with both sets of observations, while in other cases it indicated, outside the experimental uncertainty, the presence of different protein conformations in solution and in the solid state

Dynamical X-ray scattering from the relaxed structures

International Nuclear Information System (INIS)

Benediktovitch, A.; Feranchuk, I.; Ulyanenkov, A.

2009-01-01

High-resolution X-ray diffraction is now widely used analytical tool for investigation of nano scale multilayered structures in semiconductor and optical technologies. The HRXRD method delivers unique information on the crystallographic lattice of the samples, concentration of solid solutions, lattice mismatches, layer thicknesses, defect distribution, and relaxation degree of the epitaxial layers. The evaluation of the experimental results, however, requires a robust and precise theory due to complex dynamical scattering of X-rays from near perfect crystallographic structure of the samples. Usually, the Takagi-Taupin approach [1] or the recurrent matrix methods [2] are used for the simulation of the X-ray diffraction profiles from the epitaxial multilayered structures. The use of these theories, however, becomes essentially difficult, when the lateral lattice mismatches are present in multilayers, for example, in the case of partially or fully relaxed epitaxially grown samples. In the present work, the general solution of this problem is found analytically. The angular divergence of the incident beam is also considered and the algorithm for the diffracted profile mapping in the reciprocal space is developed. The experimental reciprocal space mapping of typical AlGaN/GaN/AlN samples with partially relaxed layers is compared to the simulated maps, which describe well the location and character of the diffraction spots caused by different layers. (author)

Hybrid setup for micro- and nano-computed tomography in the hard X-ray range

Science.gov (United States)

Fella, Christian; Balles, Andreas; Hanke, Randolf; Last, Arndt; Zabler, Simon

2017-12-01

With increasing miniaturization in industry and medical technology, non-destructive testing techniques are an area of ever-increasing importance. In this framework, X-ray microscopy offers an efficient tool for the analysis, understanding, and quality assurance of microscopic samples, in particular as it allows reconstructing three-dimensional data sets of the whole sample's volume via computed tomography (CT). The following article describes a compact X-ray microscope in the hard X-ray regime around 9 keV, based on a highly brilliant liquid-metal-jet source. In comparison to commercially available instruments, it is a hybrid that works in two different modes. The first one is a micro-CT mode without optics, which uses a high-resolution detector to allow scans of samples in the millimeter range with a resolution of 1 μm. The second mode is a microscope, which contains an X-ray optical element to magnify the sample and allows resolving 150 nm features. Changing between the modes is possible without moving the sample. Thus, the instrument represents an important step towards establishing high-resolution laboratory-based multi-mode X-ray microscopy as a standard investigation method.

X-ray crystallographic studies on acetylcholinesterase and on its interaction with anticholinesterase agents. Midterm report, 30 April 1993-29 April 1994

Energy Technology Data Exchange (ETDEWEB)

Silman, I.; Sussman, J.L.

1994-11-24

The EMBL-DESY synchrotron facility at Hamburg was employed to collect a complete 2.3 A data set for a crystal of native Torpedo AChE, as well as for complexes with reversible ligands, including edrophonium, d-tubocurarine and huperzine A, diffracting to similar resolution. The X26c Laue beam line at the NSLS synchrotron facility at Brookhaven National Laboratory (BNL) was used to obtain a Laue diffraction pattern for a crystal of native Torpedo AChE, diffracting out to 2.8 A. This is a first step towards our long-range objective of performing time-resolved X-ray crystallographic measurements on AChE. A complete 2.8 A data set was collected on a covalent adduct of Torpedo AChE with the transition-state analog, m -(N,N,N-trimethylammonio) trifluoroacetophenone, which serves as a powerful, quasi-irreversible inhibitor. This permitted detailed analysis of the multiple ligand-AChE interactions.

2 and 3 dimensional systems studied using x-ray crystallographic techniques

International Nuclear Information System (INIS)

Schultz, T. M.

1998-01-01

Dodecanethiol is known to self assemble on pure Au(111) surfaces. Grazing incidence X-ray diffraction (GIXD) experiments have been performed on this surface under true equilibrium conditions, using an in-situ cell. In addition an extended ex-situ data set of dodecanethiol on gold has been collected. Finally the structure of the cleaved (OOι) surface of benzamide is presented, based on GIXD measurements. Structural models for tetramethylammonium tetrafluoroborate based on rigid body TLX refinements are presented. A comparison between three different data collection methods is carried out and the appearance of a twinned structure at the 158 K phase transition is discussed. The critical temperature of the phase transition is determined. (au)

Kharkov X-ray Generator Based On Compton Scattering

International Nuclear Information System (INIS)

Shcherbakov, A.; Zelinsky, A.; Mytsykov, A.; Gladkikh, P.; Karnaukhov, I.; Lapshin, V.; Telegin, Y.; Androsov, V.; Bulyak, E.; Botman, J.I.M.; Tatchyn, R.; Lebedev, A.

2004-01-01

Nowadays X-ray sources based on storage rings with low beam energy and Compton scattering of intense laser beams are under development in several laboratories. An international cooperative project of an advanced X-ray source of this type at the Kharkov Institute of Physics and Technology (KIPT) is described. The status of the project is reviewed. The design lattice of the storage ring and calculated X-ray beam parameters are presented. The results of numerical simulation carried out for proposed facility show a peak spectral X-ray intensity of about 1014 can be produced

X-ray Topographic Investigations of Domain Structure in Czochralski Grown PrxLa1-xAlO3 Crystals

International Nuclear Information System (INIS)

Wieteska, K.; Wierzchowski, W.; Malinowska, A.; Turczynski, S.; Pawlak, D.A.; Lukasiewicz, T.; Lefeld-Sosnowska, M.; Graeff, W.

2010-01-01

In the present paper X-ray diffraction topographic techniques were applied to a number of samples cut from Czochralski grown Pr x La 1-x AlO 3 crystals with different ratio of praseodymium and lanthanum. Conventional and synchrotron X-ray topographic investigations revealed differently developed domain structures dependent on the composition of mixed praseodymium lanthanum aluminium perovskites. Some large mosaic blocks were observed together with the domains. In the best crystals, X-ray topographs revealed striation fringes and individual dislocations inside large domains. Synchrotron topographs allowed us to indicate that the domains correspond to three different crystallographic planes, and to evaluate the lattice misorientation between domains in the range of 20-50 arc min (authors)

Crystallization and preliminary X-ray crystallographic characterization of a cyclic nucleotide-binding homology domain from the mouse EAG potassium channel

International Nuclear Information System (INIS)

Marques-Carvalho, Maria João; Morais-Cabral, João Henrique

2012-01-01

The crystallization conditions and preliminary crystal characterization of the cytoplasmic cyclic nucleotide-binding homology domain from the mouse EAG potassium channel are reported. The members of the family of voltage-gated KCNH potassium channels play important roles in cardiac and neuronal repolarization, tumour proliferation and hormone secretion. These channels have a C-terminal cytoplasmic domain which is homologous to cyclic nucleotide-binding domains (CNB-homology domains), but it has been demonstrated that channel function is not affected by cyclic nucleotides and that the domain does not bind nucleotides in vitro. Here, the crystallization and preliminary crystallographic analysis of a CNB-homology domain from a member of the KCNH family, the mouse EAG channel, is reported. X-ray diffraction data were collected to 2.2 Å resolution and the crystal belonged to the hexagonal space group P3 1 21

Oblique incidence effects in direct x-ray detectors: A first-order approximation using a physics-based analytical model

International Nuclear Information System (INIS)

Badano, Aldo; Freed, Melanie; Fang Yuan

2011-01-01

Purpose: The authors describe the modifications to a previously developed analytical model of indirect CsI:Tl-based detector response required for studying oblique x-ray incidence effects in direct semiconductor-based detectors. This first-order approximation analysis allows the authors to describe the associated degradation in resolution in direct detectors and compare the predictions to the published data for indirect detectors. Methods: The proposed model is based on a physics-based analytical description developed by Freed et al. [''A fast, angle-dependent, analytical model of CsI detector response for optimization of 3D x-ray breast imaging systems,'' Med. Phys. 37(6), 2593-2605 (2010)] that describes detector response functions for indirect detectors and oblique incident x rays. The model, modified in this work to address direct detector response, describes the dependence of the response with x-ray energy, thickness of the transducer layer, and the depth-dependent blur and collection efficiency. Results: The authors report the detector response functions for indirect and direct detector models for typical thicknesses utilized in clinical systems for full-field digital mammography (150 μm for indirect CsI:Tl and 200 μm for a-Se direct detectors). The results suggest that the oblique incidence effect in a semiconductor detector differs from that in indirect detectors in two ways: The direct detector model produces a sharper overall PRF compared to the response corresponding to the indirect detector model for normal x-ray incidence and a larger relative increase in blur along the x-ray incidence direction compared to that found in indirect detectors with respect to the response at normal incidence angles. Conclusions: Compared to the effect seen in indirect detectors, the direct detector model exhibits a sharper response at normal x-ray incidence and a larger relative increase in blur along the x-ray incidence direction with respect to the blur in the

X-ray yields of superdeformed states in 193Hg

International Nuclear Information System (INIS)

Cullen, D.M.; Lee, I.Y.; Baktash, C.

1993-01-01

The K α =x-ray yields associated with the superdeformed and normal-deformed bands in 193 Hg have been measured. The results indicate an excess yield of K α -x rays in coincidence with the superdeformed cascade relative to that in coincidence with the normal-deformed cascade. The internal conversion of known transitions along the superdeformed cascade cannot account for the observed K α -x ray yield. It is likely that this excess x-ray yield is associated with low energy M1 transitions competing with the low-spin superdeformed E2 transitions. These M1 γ rays are expected to connect the two superdeformed bands which are observed in coincidence with each other. Calculations based on the measured γ-ray intensities indicate that within the experimental uncertainties the excess K α yield can be entirely accounted for by interband-M1 transitions. X-ray yields from the recent 193 Hg EUROGAM experiment will also be discussed

X-ray generator based on Compton scattering

NARCIS (Netherlands)

Androsov, V.P.; Agafonov, A.V.; Botman, J.I.M.; Bulyak, E.V.; Drebot, I.; Gladkikh, P.I.; Grevtsev, V.; Ivashchenko, V.; Karnaukhov, I.M.; Lapshin, V.I.

2005-01-01

Nowadays, the sources of the X-rays based on a storage ring with low beam energy and Compton scattering of intense laser beam are under development in several laboratories. In the paper the state-of-art in development and construction of cooperative project of a Kharkov advanced X-ray source NESTOR

X-ray imaging bilinear staggered GaAs detectors

Energy Technology Data Exchange (ETDEWEB)

Achmadullin, R.A.; Dvoryankin, V.F. E-mail: vfd217@ire216.msk.su; Dvoryankina, G.G.; Dikaev, Y.M.Yu.M.; Krikunov, A.I.; Kudryashov, A.A.; Panova, T.M.; Petrov, A.G.; Telegin, A.A

2004-09-21

The multichannel bilinear X-ray detector based on epitaxial GaAs structures is developed to obtain a digital X-ray image. Each detector operates in photovoltaic mode without reverse bias that enables almost complete elimination of detector noise arising due to leakage currents. The sensitivity range of the epitaxial GaAs photovoltaic X-ray detector covers the effective energies from 8 to 120 keV. A maximum response of the detector operating in the short-circuit mode was observed at an energy of 35 keV and amounted to 30 {mu}A min/(Gy cm{sup 2}). The multichannel detector was made of 1024 pixels with pitch of 0.8 mm. The spatial resolution of double staggered sensor row is twice as high as the resolution of that of single sensor row with the same pitch. Measured spatial resolution is 1.2 line-pairs/mm, contrast sensitivity not worse 1% and dynamic range defined as the ratio of maximum detectable X-ray signal to electronic noise level more than 2000 are received.

X-ray imaging bilinear staggered GaAs detectors

International Nuclear Information System (INIS)

Achmadullin, R.A.; Dvoryankin, V.F.; Dvoryankina, G.G.; Dikaev, Y.M.Yu.M.; Krikunov, A.I.; Kudryashov, A.A.; Panova, T.M.; Petrov, A.G.; Telegin, A.A.

2004-01-01

The multichannel bilinear X-ray detector based on epitaxial GaAs structures is developed to obtain a digital X-ray image. Each detector operates in photovoltaic mode without reverse bias that enables almost complete elimination of detector noise arising due to leakage currents. The sensitivity range of the epitaxial GaAs photovoltaic X-ray detector covers the effective energies from 8 to 120 keV. A maximum response of the detector operating in the short-circuit mode was observed at an energy of 35 keV and amounted to 30 μA min/(Gy cm 2 ). The multichannel detector was made of 1024 pixels with pitch of 0.8 mm. The spatial resolution of double staggered sensor row is twice as high as the resolution of that of single sensor row with the same pitch. Measured spatial resolution is 1.2 line-pairs/mm, contrast sensitivity not worse 1% and dynamic range defined as the ratio of maximum detectable X-ray signal to electronic noise level more than 2000 are received

Performances for confocal X-ray diffraction technology based on polycapillary slightly focusing X-ray optics

Energy Technology Data Exchange (ETDEWEB)

Liu, Hehe; Liu, Zhiguo [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Sun, Tianxi, E-mail: stxbeijing@163.com [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Peng, Song [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Ma, Yongzhong [Center for Disease Control and Prevention of Beijing, Beijing 100013 (China); Sun, Weiyuan; Li, Yude; Lin, Xiaoyan; Zhao, Weigang; Zhao, Guangcui; Luo, Ping; Pan, Qiuli; Ding, Xunliang [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

2013-09-21

The confocal X-ray diffraction (XRD) technology based on a polycapillary slightly focusing X-ray lens (PSFXRL) in excitation channel and a polycapillary parallel X-ray lens (PPXRL) with a long input focal distance in detection channel was developed. The output focal spot of the PSFXRL and the input focal spot of the PPXRL were adjusted in confocal configuration, and only the X-rays from the volume overlapped by these foci could be accordingly detected. This confocal configuration was helpful in decreasing background. The convergence of the beam focused by the PSFXRL and divergence of the beam which could be collected by the PPXRL with a long input focal distance were both about 9 mrad at 8 keV. This was helpful in improving the resolution of lattice spacing of this confocal XRD technology. The gain in power density of such PSFXRL and PPXRL was about 120 and 7 at 11 keV, respectively, which was helpful in using the low power source to perform XRD analysis efficiently. The performances of this confocal XRD technology were provided, and some common plastics were analyzed. The experimental results demonstrated that the confocal diffraction technology base on polycapillary slightly focusing X-ray optics had wide potential applications.

A mirror for lab-based quasi-monochromatic parallel x-rays.

Science.gov (United States)

Nguyen, Thanhhai; Lu, Xun; Lee, Chang Jun; Jung, Jin-Ho; Jin, Gye-Hwan; Kim, Sung Youb; Jeon, Insu

2014-09-01

A multilayered parabolic mirror with six W/Al bilayers was designed and fabricated to generate monochromatic parallel x-rays using a lab-based x-ray source. Using this mirror, curved bright bands were obtained in x-ray images as reflected x-rays. The parallelism of the reflected x-rays was investigated using the shape of the bands. The intensity and monochromatic characteristics of the reflected x-rays were evaluated through measurements of the x-ray spectra in the band. High intensity, nearly monochromatic, and parallel x-rays, which can be used for high resolution x-ray microscopes and local radiation therapy systems, were obtained.

OBSERVATIONS OF X-RAY OSCILLATIONS IN ξ BOO: EVIDENCE OF A FAST-KINK MODE IN THE STELLAR LOOPS

International Nuclear Information System (INIS)

Pandey, J. C.; Srivastava, A. K.

2009-01-01

We report the observations of X-ray oscillations during the flare in a cool active star ξ Boo for the first time. ξ Boo was observed by EPIC/MOS of the XMM-Newton satellite. The X-ray light curve is investigated with wavelet and periodogram analyses. Both analyses clearly show oscillations of the period of ∼1019 s. We interpret these oscillations as a fundamental fast-kink mode of magnetoacoustic waves.

Catalase induction in normal and tumorigenic mice using x-rays, clofibrate, ethanol, or hydrogen peroxide

International Nuclear Information System (INIS)

Alexander, L.; Oberley, L.

1985-01-01

The authors studied catalase induction in normal male Swiss mice as well as in male mice harboring H-6 hepatomas. The induction patterns many suggest reasons why tumor cells have lower catalase activity than normal cells. X-rays, hydrogen peroxide, ethanol, and clofibrate were used as inducing agents. X-rays interact with tissue and cause free radical formation. This results in an increase in hydrogen peroxide concentration, which ought to induce catalase. Oral administration of hydrogen peroxide should induce catalase similarly. Ethanol can be a substrate for catalase, forming acetalehyde; and as such may induce catalase. Ethanol can also restore inactive catalase compound II to useful catalase. Clofibrate is a hypolipidemic agent which induces catalase, most likely because of its ability to accelerate lipid breakdown, which raises peroxide concentration

Nondestructive mapping of chemical composition and structural qualities of group III-nitride nanowires using submicron beam synchrotron-based X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Bonanno, P.L., E-mail: plb2@njit.edu [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Gautier, S. [LMOPS + UMI: Laboratoire Matériaux Optiques, Photonique et micro-nano Systèmes, UMR CNRS 7132, Université de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz, France, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Gmili, Y.El.; Moudakir, T. [UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Sirenko, A.A. [Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Kazimirov, A. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Cai, Z.-H. [Advanced Photon Source, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Martin, J. [LMOPS + UMI: Laboratoire Matériaux Optiques, Photonique et micro-nano Systèmes, UMR CNRS 7132, Université de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz, France, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Goh, W.H. [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Martinez, A.; Ramdane, A.; Le Gratiet, L. [Laboratoire de Photonique et de Nanostructures, UPR CNRS 20, Route de Nozay, 91460 Marcoussis (France); Maloufi, N. [Laboratoire d' Etude des Textures et Application aux Matériaux UMR CNRS 7078 Ile du Saulcy 57045 METZ cedex 1 (France); Assouar, M.B. [Laboratoire de Physique des Milieux Ionisés et Applications, Nancy University, CNRS, BP 239, F-54506 Vandoeuvre-lès-Nancy Cédex (France); Ougazzaden, A. [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France)

2013-08-31

Submicron beam synchrotron-based X-ray diffraction (XRD) techniques have been developed and used to accurately and nondestructively map chemical composition and material quality of selectively grown group III-nitride nanowires. GaN, AlGaN, and InGaN multi-quantum-well nanowires have been selectively grown on lattice matched and mismatched substrates, and the challenges associated with obtaining and interpreting submicron beam XRD results are addressed and solved. Nanoscale cathodoluminescence is used to examine exciton behavior, and energy-dispersive X-ray spectroscopy is used to verify chemical composition. Scanning transmission electron microscopy is later used to paint a more complete picture. The advantages of submicron beam XRD over other techniques are discussed in the context of this challenging material system. - Highlights: ► We used nano selective area growth to create nanowires of GaN, AlGaN and InGaN/GaN. ► We characterized them by synchrotron-based submicron beam X-ray diffraction (XRD). ► This technique accurately determined chemical and crystallographic properties. ► Challenges of XRD are addressed in the context of this challenging material system. ► Advantages of XRD over other characterization methods are discussed.

High-resolution 3D imaging of polymerized photonic crystals by lab-based x-ray nanotomography with 50-nm resolution

Science.gov (United States)

Yin, Leilei; Chen, Ying-Chieh; Gelb, Jeff; Stevenson, Darren M.; Braun, Paul A.

2010-09-01

High resolution x-ray computed tomography is a powerful non-destructive 3-D imaging method. It can offer superior resolution on objects that are opaque or low contrast for optical microscopy. Synchrotron based x-ray computed tomography systems have been available for scientific research, but remain difficult to access for broader users. This work introduces a lab-based high-resolution x-ray nanotomography system with 50nm resolution in absorption and Zernike phase contrast modes. Using this system, we have demonstrated high quality 3-D images of polymerized photonic crystals which have been analyzed for band gap structures. The isotropic volumetric data shows excellent consistency with other characterization results.

Real-time observation of epitaxial crystal growth in gaseous environment using x-ray diffraction and x-ray reflectometry

International Nuclear Information System (INIS)

Kawamura, Tomoaki; Bhunia, Satyaban; Watanabe, Yoshio; Fujikawa, Seiji

2008-01-01

We made the x-ray diffractometer combined with the MOCVD growth system for the real-time observation of epitaxial growth in gaseous environment, and investigated the growth mechanism of InP crystals. Changes of the (-5/2 O) Bragg diffraction during the growth revealed that the growth starts immediately after the In source has been supplied and gradually stopped, owing to the migrating In atoms on the surface. Additionally, one can easily determine the growth modes, including 3-dimensional mode, layer-by-layer mode, and step-flow mode, by observing the change of x-ray reflectivity with various growth conditions. (author)

Laboratory soft x-ray microscopy and tomography

International Nuclear Information System (INIS)

Bertilson, Michael

2011-01-01

Soft x-ray microscopy in the water-window (λ = 2.28 nm - 4.36 nm) is based on zone-plate optics and allows high-resolution imaging of, e.g., cells and soils in their natural or near-natural environment. Three-dimensional imaging is provided via tomographic techniques, soft x-ray cryo tomography. However, soft x-ray microscopes with such capabilities have been based on large-scale synchrotron x-ray facilities, thereby limiting their accessibility for a wider scientific community. This Thesis describes the development of the Stockholm laboratory soft x-ray microscope to three-dimensional cryo tomography and to new optics-based contrast mechanisms. The microscope relies on a methanol or nitrogen liquid-jet laser-plasma source, normal-incidence multilayer or zone-plate condenser optics, in-house fabricated zone-plate objectives, and allows operation at two wavelengths in the water-window, λ = 2.48 nm and λ = 2.48 nm. With the implementation of a new state-of-the-art normal-incidence multilayer condenser for operation at λ = 2.48 nm and a tiltable cryogenic sample stage the microscope now allows imaging of dry, wet or cryo-fixed samples. This arrangement was used for the first demonstration of laboratory soft x-ray cryo microscopy and tomography. The performance of the microscope has been demonstrated in a number of experiments described in this Thesis, including, tomographic imaging with a resolution of 140 nm, cryo microscopy and tomography of various cells and parasites, and for studies of aqueous soils and clays. The Thesis also describes the development and implementation of single-element differential-interference and Zernike phase-contrast zone-plate objectives. The enhanced contrast provided by these optics reduce exposure times or lowers the dose in samples and are of major importance for harder x-ray microscopy. The implementation of a high-resolution 50 nm compound zone-plate objective for sub-25-nm resolution imaging is also described. All experiments

xMDFF: molecular dynamics flexible fitting of low-resolution X-ray structures

International Nuclear Information System (INIS)

McGreevy, Ryan; Singharoy, Abhishek; Li, Qufei; Zhang, Jingfen; Xu, Dong; Perozo, Eduardo; Schulten, Klaus

2014-01-01

A new real-space refinement method for low-resolution X-ray crystallography is presented. The method is based on the molecular dynamics flexible fitting protocol targeted at addressing large-scale deformations of the search model to achieve refinement with minimal manual intervention. An explanation of the method is provided, augmented by results from the refinement of both synthetic and experimental low-resolution data, including an independent electrophysiological verification of the xMDFF-refined crystal structure of a voltage-sensor protein. X-ray crystallography remains the most dominant method for solving atomic structures. However, for relatively large systems, the availability of only medium-to-low-resolution diffraction data often limits the determination of all-atom details. A new molecular dynamics flexible fitting (MDFF)-based approach, xMDFF, for determining structures from such low-resolution crystallographic data is reported. xMDFF employs a real-space refinement scheme that flexibly fits atomic models into an iteratively updating electron-density map. It addresses significant large-scale deformations of the initial model to fit the low-resolution density, as tested with synthetic low-resolution maps of d-ribose-binding protein. xMDFF has been successfully applied to re-refine six low-resolution protein structures of varying sizes that had already been submitted to the Protein Data Bank. Finally, via systematic refinement of a series of data from 3.6 to 7 Å resolution, xMDFF refinements together with electrophysiology experiments were used to validate the first all-atom structure of the voltage-sensing protein Ci-VSP

xMDFF: molecular dynamics flexible fitting of low-resolution X-ray structures

Energy Technology Data Exchange (ETDEWEB)

McGreevy, Ryan; Singharoy, Abhishek [University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Li, Qufei [The University of Chicago, Chicago, IL 60637 (United States); Zhang, Jingfen; Xu, Dong [University of Missouri, Columbia, MO 65211 (United States); Perozo, Eduardo [The University of Chicago, Chicago, IL 60637 (United States); Schulten, Klaus, E-mail: kschulte@ks.uiuc.edu [University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2014-09-01

A new real-space refinement method for low-resolution X-ray crystallography is presented. The method is based on the molecular dynamics flexible fitting protocol targeted at addressing large-scale deformations of the search model to achieve refinement with minimal manual intervention. An explanation of the method is provided, augmented by results from the refinement of both synthetic and experimental low-resolution data, including an independent electrophysiological verification of the xMDFF-refined crystal structure of a voltage-sensor protein. X-ray crystallography remains the most dominant method for solving atomic structures. However, for relatively large systems, the availability of only medium-to-low-resolution diffraction data often limits the determination of all-atom details. A new molecular dynamics flexible fitting (MDFF)-based approach, xMDFF, for determining structures from such low-resolution crystallographic data is reported. xMDFF employs a real-space refinement scheme that flexibly fits atomic models into an iteratively updating electron-density map. It addresses significant large-scale deformations of the initial model to fit the low-resolution density, as tested with synthetic low-resolution maps of d-ribose-binding protein. xMDFF has been successfully applied to re-refine six low-resolution protein structures of varying sizes that had already been submitted to the Protein Data Bank. Finally, via systematic refinement of a series of data from 3.6 to 7 Å resolution, xMDFF refinements together with electrophysiology experiments were used to validate the first all-atom structure of the voltage-sensing protein Ci-VSP.

A Journey into Reciprocal Space; A crystallographer's perspective

Science.gov (United States)

Glazer, A. M.

2017-10-01

This book introduces undergraduate and graduate students to a crystallographer's view of real and reciprocal space, a concept that has been of particular use by crystallographers to understand the patterns of spots when x-rays are diffracted by crystals. It then proceeds to develop the concept in a form suitable for physics applications; such as how solid-state physicists use reciprocal space to explain various solid-state properties such as thermal and electrical phenomena.

Temporally coherent x-ray laser with the high order harmonic light

International Nuclear Information System (INIS)

Hasegawa, Noboru; Kawachi, Tetsuya; Kishimoto, Maki; Sukegawa, Kouta; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Kawazome, Hayato; Nagashima, Keisuke

2005-01-01

We obtained the neon-like manganese x-ray laser with the injection of the high order harmonic light as the seed x-ray at the wavelength of 26.9 nm for the purpose of generation of the temporally coherent x-ray laser. The x-ray amplifier, which has quite narrow spectral width, selected and amplified the temporally coherent mode of the harmonic light. The temporal coherence of the mode selected harmonic light was nearly transform limited pulse, and the obtained x-ray laser with the seed x-ray expected to be nearly temporally coherent x-ray. (author)

Scintillating ribbon x-ray detector

International Nuclear Information System (INIS)

Kinchen, B.E.; Rogers, A.

1995-01-01

A patent in the early 1970's by Aerojet Corporation in Sacramento, CA put forth the idea of using an array of scintillating fibers for x-ray detection and imaging. In about 1975, Pratt and Whitney Aircraft in East Hartford, CT designed and manufactured an imaging system based on the patent. The device was 1.75 in thick in the direction of the x-ray beam and about 4 in. by 4 in. square. The device was used with a 8 MeV x-ray source to image and measure internal clearances within operating aircraft, gas turbines engines. There are significant advantages of fiber optic detectors in x-ray detection. However, the advantages are often outweighed by the disadvantages. Two of the advantages of scintillating fiber optic x-ray detectors are: (1) high limiting spatial frequency -- between 20 and 25 lp/mm; and (2) excellent x-ray stopping power -- they can be made thick and retain spatial resolution. In traditional fiber optic detectors the x-rays are oriented parallel to the long axis of the fiber. For the scintillating ribbon x-ray sensor, the x-rays are oriented normal to the fiber long axis. This ribbon sensor technique has a number of advantages over the two current radiographic techniques digital x-radiography and x-ray film: The main advantage the ribbon has is size and shape. It can be as thin as 0.05 in., virtually any width or length, and flexible. Once positioned in a given location, 20 to 100 square inches of the object being inspected can be imaged with a single x-ray beam sweep. It is clear that conventional digital cameras do not lend themselves to placement between walls of aircraft structures or similar items requiring x-ray inspections. A prototype scintillating ribbon x-ray sensor has been fabricated and tested by Synergistic Detector Designs. Images were acquired on corrosion test panels of aluminum fabricated by Iowa State University

Surface crystallographic structures of cellulose nanofiber films and overlayers of pentacene

Science.gov (United States)

Nakayama, Yasuo; Mori, Toshiaki; Tsuruta, Ryohei; Yamanaka, Soichiro; Yoshida, Koki; Imai, Kento; Koganezawa, Tomoyuki; Hosokai, Takuya

2018-03-01

Cellulose nanofibers or nanocellulose is a promising recently developed biomass and biodegradable material used for various applications. In order to utilize this material as a substrate in organic electronic devices, thorough understanding of the crystallographic structures of the surfaces of the nanocellulose composites and of their interfaces with organic semiconductor molecules is essential. In this work, surface crystallographic structures of nanocellulose films (NCFs) and overlayers of pentacene were investigated by two-dimensional grazing-incidence X-ray diffraction. The NCFs are found to crystallize on solid surfaces with the crystal lattice preserving the same structure of the known bulk phase, whereas distortion of interchain packing toward the surface normal direction is suggested. The pentacene overlayers on the NCFs are found to form the thin-film phase with an in-plane mean crystallite size of over 10 nm.

Raman spectroscopy and X-ray diffraction studies on celestite

International Nuclear Information System (INIS)

Chen Yenhua; Yu Shucheng; Huang, Eugene; Lee, P.-L.

2010-01-01

High-pressure Raman spectroscopy and X-ray diffraction studies of celestite (SrSO 4 ) were carried out in a diamond anvil cell at room temperature. Variation in the Raman vibrational frequency and change of lattice parameters with pressure indicate that a transformation occurs in celestite. This transformation caused an adjustment in the Sr-O polyhedra that affected the stretching-force constant of SO 4 . Moreover, compressibilities along the crystallographic axes decreased in the order a to c to b. From the compression data, the bulk modulus of the celestite was 87 GPa. Both X-ray and Raman data show that the transition in celestite is reversible.

xMDFF: molecular dynamics flexible fitting of low-resolution X-ray structures.

Science.gov (United States)

McGreevy, Ryan; Singharoy, Abhishek; Li, Qufei; Zhang, Jingfen; Xu, Dong; Perozo, Eduardo; Schulten, Klaus

2014-09-01

X-ray crystallography remains the most dominant method for solving atomic structures. However, for relatively large systems, the availability of only medium-to-low-resolution diffraction data often limits the determination of all-atom details. A new molecular dynamics flexible fitting (MDFF)-based approach, xMDFF, for determining structures from such low-resolution crystallographic data is reported. xMDFF employs a real-space refinement scheme that flexibly fits atomic models into an iteratively updating electron-density map. It addresses significant large-scale deformations of the initial model to fit the low-resolution density, as tested with synthetic low-resolution maps of D-ribose-binding protein. xMDFF has been successfully applied to re-refine six low-resolution protein structures of varying sizes that had already been submitted to the Protein Data Bank. Finally, via systematic refinement of a series of data from 3.6 to 7 Å resolution, xMDFF refinements together with electrophysiology experiments were used to validate the first all-atom structure of the voltage-sensing protein Ci-VSP.

Projection-type X-ray microscope based on a spherical compound refractive X-ray lens

OpenAIRE

Dudchik, Yu. I.; Gary, C. K.; Park, H.; Pantell, R. H.; Piestrup, M. A.

2007-01-01

New projection- type X-ray microscope with a compound refractive lens as the optical element is presented. The microscope consists of an X-ray source that is 1-2 mm in diameter, compound X-ray lens and X-ray camera that are placed in-line to satisfy the lens formula. The lens forms an image of the X-ray source at camera sensitive plate. An object is placed between the X-ray source and the lens as close as possible to the source, and the camera shows a shadow image of the object. Spatial resol...

Carbon-based Fresnel optics for hard x-ray astronomy.

Science.gov (United States)

Braig, Christoph; Zizak, Ivo

2018-03-10

We investigate the potential of large-scale diffractive-refractive normal-incidence transmission lenses for the development of space-based hard x-ray telescopes with an angular resolution in the range of (10 -6 -10 -3 )  arcsec over a field of view that is restricted by the available detector size. Coherently stepped achromatic lenses with diameters up to 5 m for compact apertures and 13 m in the case of segmentation provide an access to spectrally resolved imaging within keV-wide bands around the design energy between 10 and 30 keV. Within an integration time of 10 6   s, a photon-limited 5σ sensitivity down to (10 -9 -10 -7 )  s -1  cm -2  keV -1 can be achieved depending on the specific design. An appropriate fabrication strategy, feasible nowadays with micro-optical technologies, is considered and relies on the availability of high-purity carbon or polymer membranes. X-ray fluorescence measurements of various commercially available carbon-based materials prove for most of them the existence of a virtually negligible contamination by critical trace elements such as transition metals on the ppm level.

Irradiated ISM : Discriminating between cosmic rays and X-rays

NARCIS (Netherlands)

Meijerink, R.; Spaans, M.; Israel, F. P.

2006-01-01

The interstellar medium ( ISM) at the centers of active galaxies is exposed to a combination of cosmic-ray, far-ultraviolet (FUV), and X-ray radiation. We apply photodissociation region (PDR) models to this ISM with both "normal" and highly elevated (5 x 10(-15) s(-1)) cosmic- ray (CR) rates and

X-ray residual macrostress of texturized polycrystals from pole figures

International Nuclear Information System (INIS)

Gokhman, A.R.

1994-01-01

It was shown that the crystallographic correlation of properties of the mono- and polycrystals is determined by some integral characteristics of the texture (ICT). For the calculation of the X-ray elastic modulus the ICT are determined by integration not all the pole figure, as in case of mechanical modulus, but only in the region, in which the condition of the coincidence of orientation of the reflex, chosen for determining of the residual deformation, and chosen direction in the polycrystal is full filled. X-ray residual macrostress of the rolling sheets Ti-alloys was carried out. (orig.)

X-ray transparent Microfluidics for Protein Crystallization and Biomineralization

Science.gov (United States)

Opathalage, Achini

Protein crystallization demands the fundamental understanding of nucleation and applying techniques to find the optimal conditions to achieve the kinetic pathway for a large and defect free crystal. Classical nucleation theory predicts that the nucleation occurs at high supersaturation conditions. In this dissertation we sought out to develop techniques to attain optimal supersaturation profile to a large defect free crystal and subject it to in-situ X-ray diffraction using microfluidics. We have developed an emulsion-based serial crystallographic technology in nanolitre-sized droplets of protein solution encapsulated in to nucleate one crystal per drop. Diffraction data are measured, one crystal at a time, from a series of room temperature crystals stored on an X-ray semi-transparent microfluidic chip, and a 93% complete data set is obtained by merging single diffraction frames taken from different un-oriented crystals. As proof of concept, the structure of Glucose Isomerase was solved to 2.1 A. We have developed a suite of X-ray semi-transparent micrfluidic devices which enables; controlled evaporation as a method of increasing supersaturation and manipulating the phase space of proteins and small molecules. We exploited the inherently high water permeability of the thin X-ray semi-transparent devices as a mean of increasing the supersaturation by controlling the evaporation. We fabricated the X-ray semi-transparent version of the PhaseChip with a thin PDMS membrane by which the storage and the reservoir layers are separated, and studies the phase transition of amorphous CaCO3.

Photovoltaic x-ray detectors based on the GaAs epitaxial structures

CERN Document Server

Akhmadullin, R A; Dvoryankina, G G; Dikaev, Y M; Ermakov, M G; Ermakova, O N; Krikunov, A I; Kudryashov, A A; Petrov, A G; Telegin, A A

2002-01-01

The new photovoltaic detector of the X-ray radiation is proposed on the basis of the GaAs epitaxial structures, which operates with high efficiency of the charge carriers collection without shift voltage and at the room temperature. The structures are grown by the method of the gas-phase epitaxy on the n sup + -type highly-alloyed substrates. The range of sensitivity to the X-ray radiation is within the range of effective energies from 8 up to 120 keV. The detector maximum response in the current short circuit mode is determined

Applications of phase-contrast x-ray imaging to medicine using an x-ray interferometer

Science.gov (United States)

Momose, Atsushi; Yoneyama, Akio; Takeda, Tohoru; Itai, Yuji; Tu, Jinhong; Hirano, Keiichi

1999-10-01

We are investigating possible medical applications of phase- contrast X-ray imaging using an X-ray interferometer. This paper introduces the strategy of the research project and the present status. The main subject is to broaden the observation area to enable in vivo observation. For this purpose, large X-ray interferometers were developed, and 2.5 cm X 1.5 cm interference patterns were generated using synchrotron X-rays. An improvement of the spatial resolution is also included in the project, and an X-ray interferometer designed for high-resolution phase-contrast X-ray imaging was fabricated and tested. In parallel with the instrumental developments, various soft tissues are observed by phase- contrast X-ray CT to find correspondence between the generated contrast and our histological knowledge. The observation done so far suggests that cancerous tissues are differentiated from normal tissues and that blood can produce phase contrast. Furthermore, this project includes exploring materials that modulate phase contrast for selective imaging.

Atypical locations of retropharyngeal abscess: beware of the normal lateral soft tissue neck X-ray.

LENUS (Irish Health Repository)

Uzomefuna, Vincent

2012-02-01

Retropharyngeal abscesses (RPA) are uncommon but potentially lethal deep neck space infections, over 95% of which occur in children under six years of age. Without a high index of suspicion, early recognition and prompt intervention, catastrophic consequences can ensue, and mortality can be as high as 60% if jugular vein thrombosis or mediastinitis occurs. While older children may have specific complaints referable to the pharynx, infants and young children may present with vague symptoms. To date, a lot of emphasis continues to be placed on the importance of lateral soft tissue neck X-ray in the diagnosis and management of patients with suspected retropharyngeal abscesses; and lateral neck X-ray has been cited as the most useful radiological view of the laryngopharynx. While we recognise the role of lateral neck X-rays in retropharyngeal and other upper airway pathologies, we present three case series in which lateral neck X-rays were normal and diagnosis was made only after CT scanning. These three cases were unusual as the abscesses were located high in the naso-pharynx making them impossible to detect on the lateral soft tissue neck X-rays and this underscores the need for high index of suspicion and prompt CT or MRI scanning, in any child with symptoms or signs suggestive of a possible retropharyngeal abscess.

Confocal total reflection X-ray fluorescence technology based on an elliptical monocapillary and a parallel polycapillary X-ray optics.

Science.gov (United States)

Zhu, Yu; Wang, Yabing; Sun, Tianxi; Sun, Xuepeng; Zhang, Xiaoyun; Liu, Zhiguo; Li, Yufei; Zhang, Fengshou

2018-07-01

A total reflection X-ray fluorescence (TXRF) spectrometer based on an elliptical monocapillary X-ray lens (MXRL) and a parallel polycapillary X-ray lens (PPXRL) was designed. This TXRF instrument has micro focal spot, low divergence and high intensity of incident X-ray beam. The diameter of the focal spot of MXRL was 16.5 µm, and the divergence of the incident X-ray beam was 3.4 mrad. We applied this TXRF instrument to the micro analysis of a single-layer film containing Ni deposited on a Si substrate by metal vapor vacuum arc ion source. Copyright © 2018 Elsevier Ltd. All rights reserved.

Imaging Macromolecules with X-ray laser pulses

CERN Multimedia

CERN. Geneva

2017-01-01

The short wavelength of X-rays allows us to resolve atoms, but in practise for biological materials the achievable resolution is limited by the destruction of the sample by the radiation that forms the image.  For over 100 years, the workaround to this problem of radiation damage has been to average signals from repeating copies of the object arranged in a large crystal.  It is now possible to overcome damage limits by using intense X-ray pulses that vaporise the sample, but which are short enough in duration to freeze any motion of the sample on the atomic scale.  With the advent of X-ray FELs we have been able to confirm this principle, and are now applying it to overcoming a major bottleneck for protein crystallography, which is the need for large well-diffracting crystals.  The intense pulses also open up opportunities to help solve the crystallographic phase problem.  In particular we have found that commonly-occurring disordered crystals that are usually not ...

Normal rejoining of DNA strand breaks in ataxia telangiectasia fibroblast lines after low x-ray exposure

International Nuclear Information System (INIS)

Hariharan, P.V.; Eleczko, S.; Smith, B.P.; Paterson, M.C.

1981-01-01

The alkaline elution method was used to measure the enzymatic repair of x-ray-induced DNA strand breaks in skin fibroblasts derived from human subjects afflicted with ataxia telangiectasia (AT). Monolayer cultures of normal control and AT cell lines were exposed acutely to moderately lethal (250-rad) and highly lethal (1250-rad) doses of 250-kV x rays under aerobic conditions. Upon receiving 250 rad, the control fibroblasts from a clinically normal donor rejoined all detectable single-strand breaks (plus alkali-labile bonds) within 30 to 60 min of incubation. When challenged with 1250 rad the kinetics of strand rejoining by the normal control cells were biphasic. For both exposures, no significant difference in either the rate or the extent of strand rejoining was detected between the normal cell line (GM38) and three mutant cell lines (AT2BE, AT3BI, AT4BI) belonging to the three known genetic complementation groups in AT. It would thus appear that the enhanced radiosensitivity of cultured AT cells does not stem from faulty rejoining of radiogenic DNA strand breaks

Crystallographically uniform arrays of ordered (In)GaN nanocolumns

Energy Technology Data Exchange (ETDEWEB)

Gačević, Ž., E-mail: gacevic@isom.upm.es; Bengoechea-Encabo, A.; Albert, S.; Calleja, E. [ETSIT-ISOM, Universidad Politécnica de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Torres-Pardo, A.; González-Calbet, J. M. [Dept. Química Inorgánica, Universidad Complutense, 28040 Madrid (Spain); CEI Campus Moncloa, UCM-UPM, Madrid (Spain)

2015-01-21

In this work, through a comparative study of self-assembled (SA) and selective area grown (SAG) (In)GaN nanocolumn (NC) ensembles, we first give a detailed insight into improved crystallographic uniformity (homogeneity of crystallographic tilts and twists) of the latter ones. The study, performed making use of: reflective high energy electron diffraction, X-ray diffraction and scanning electron microscopy, reveals that unlike their SA counterparts, the ensembles of SAG NCs show single epitaxial relationship to both sapphire(0001) and Si(111) underlying substrates. In the second part of the article, making use of X-ray diffraction, we directly show that the selective area growth leads to improved compositional uniformity of InGaN NC ensembles. This further leads to improved spectral purity of their luminescence, as confirmed by comparative macro-photoluminescence measurements performed on SA and SAG InGaN NC ensembles. An improved crystallographic uniformity of NC ensembles facilitates their integration into optoelectronic devices, whereas their improved compositional uniformity allows for their employment in single-color optoelectronic applications.

A compact scanning soft X-ray microscope

International Nuclear Information System (INIS)

Trail, J.A.

1989-01-01

Soft x-ray microscopes operating at wavelengths between 2.3 nm and 4.4 nm are capable of imaging wet biological cells with a resolution many times that of a visible light microscope. Several such soft x-ray microscopes have been constructed. However, with the exception of contact microscopes, all use synchrotrons as the source of soft x-ray radiation and Fresnel zone plates as the focusing optics. These synchrotron based microscopes are very successful but have the disadvantage of limited access. This dissertation reviews the construction and performance of a compact scanning soft x-ray microscope whose size and accessibility is comparable to that of an electron microscope. The microscope uses a high-brightness laser-produced plasma as the soft x-ray source and normal incidence multilayer-coated mirrors in a Schwarzschild configuration as the focusing optics. The microscope operates at a wavelength of 14 nm, has a spatial resolution of 0.5 μm, and has a soft x-ray photon flux through the focus of 10 4 -10 5 s -1 when operated with only 170 mW of average laser power. The complete system, including the laser, fits on a single 4' x 8' optical table. The significant components of the compact microscope are the laser-produced plasma (LPP) source, the multilayer coatings, and the Schwarzschild objective. These components are reviewed, both with regard to their particular use in the current microscope and with regard to extending the microscope performance to higher resolution, higher speed, and operation at shorter wavelengths. Measurements of soft x-ray emission and debris emission from our present LPP source are presented and considerations given for an optimal LPP source. The LPP source was also used as a broadband soft x-ray source for measurement of normal incidence multilayer mirror reflectance in the 10-25 nm spectral region

Characterization of Polycrystalline Materials Using Synchrotron X-ray Imaging and Diffraction Techniques

DEFF Research Database (Denmark)

Ludwig, Wolfgang; King, A.; Herbig, M.

2010-01-01

The combination of synchrotron radiation x-ray imaging and diffraction techniques offers new possibilities for in-situ observation of deformation and damage mechanisms in the bulk of polycrystalline materials. Minute changes in electron density (i.e., cracks, porosities) can be detected using...... propagation based phase contrast imaging, a 3-D imaging mode exploiting the coherence properties of third generation synchrotron beams. Furthermore, for some classes of polycrystalline materials, one may use a 3-D variant of x-ray diffraction imaging, termed x-ray diffraction contrast tomography. X-ray...

X-ray Fourier-transform holographic microscope

International Nuclear Information System (INIS)

Haddad, W.S.; Cullen, D.; Solem, J.C.; Boyer, K.; Rhodes, C.K.

1988-01-01

The properties of an x-ray Fourier-transform holographic instrument suitable for imaging hydrated biological samples are described. Recent advances in coherent x-ray source technology are making diffraction-limited holograms of microscopic structures, with corresponding high spatial resolution, a reality. A high priority application of snapshot x-ray holography is the study of microscopic biological structures in the hydrated living state. X-rays offer both high resolution and high contrast for important structures within living organisms, thereby rendering unnecessary the staining of specimens, essential for optical and electron microscopy. If the wavelength is properly chosen. Furthermore, the snapshot feature, arising from picosecond or subpicosecond exposure times, eliminates blurring occurring from either thermal heating or normal biological activity of the sample. Finally, with sufficiently high photon fluxes, such as those available from x-ray lasers, the x-ray snapshot can be accomplished with a single pulse, thereby yielding complete three-dimensional information on a sample having normal biological integrity at the moment of exposure. 10 refs., 6 figs

Stress measurement by x-ray diffractometry

Energy Technology Data Exchange (ETDEWEB)

Mitchell, C M

1985-10-22

This invention relates to x-ray diffractometry and more particularly to apparatus and methods for the measurement of residual stress in polycrystalline, e.g. metallic, specimens. The procedure is based on measurement of the lattice strain of crystals by x-ray diffraction, in which change in the interplanar spacing of a set of crystal lattice planes due to strain causes a change in the diffraction angle of the scattered x-ray beam, from which latter change the magnitude of the strain can be determined. In a polycrystalline specimen, from well know relations for elastic behaviour in isotropic materials, the stress on a plane normal to a given direction in the surface has a component in the given direction which can be calculated from measurement of lattice strain in two directions in a plane containing the given direction and the normal to the specimen surface. In general three such stress components in three directions in the surface are required to determine the principal stresses and thus express the state of stress in the surface. (author). 2 tabs., 9 figs.

Crystallization and preliminary X-ray crystallographic characterization of TrmFO, a folate-dependent tRNA methyltransferase from Thermotoga maritima

International Nuclear Information System (INIS)

Cicmil, Nenad

2008-01-01

T. maritima TrmFO was overexpressed, purified and crystallized. A diffraction data set was collected to a resolution of 2.6 Å. TrmFO, previously classified as GID, is a methyltransferase that catalyzes the formation of 5-methyluridine or ribothymidine (T) at position 54 in tRNA in some Gram-positive bacteria. To date, TrmFO is the only characterized tRNA methyltransferase that does not use S-adenosylmethionine as the methyl-group donor. Instead, the donor of the methyl group is N 5 ,N 10 -methylenetetrahydrofolate. The crystallization and preliminary X-ray crystallographic studies of TrmFO are reported here. The recombinant protein, cloned from Thermotoga maritima genomic DNA, was overproduced in Esherichia coli and crystallized in 25%(v/v) PEG 4000, 100 mM NaCl and sodium citrate buffer pH 5.0 at 291 K using the hanging-drop vapor-diffusion method. The plate-shaped crystals diffracted to 2.6 Å and belong to the orthorhombic space group P2 1 2 1 2 1 , with unit-cell parameters a = 79.94, b = 92.46, c = 127.20 Å

Crystallographic and 119Sn and 155Gd Moessbauer analyses of Gd5Ge2(Si1-xSnx)2 (x = 0.23 and x = 0.40)

International Nuclear Information System (INIS)

Campoy, J. C. P.; Santos, A. O. dos; Cardoso, L. P.; Paesano, A.; Raposo, M. T.; Fabris, J. D.

2010-01-01

We report the structural characterization of Gd 5 Ge 2 (Si 1-x Sn x ) 2 (x = 0.23 and x = 0.40) compounds by means of 100 and 298 K-X-ray diffractometry (XRD) and 4 K- 155 Gd and 298 K- 119 Sn Moessbauer spectroscopy. These compounds order ferromagnetically at 218.4 and 172.7 K, respectively. At ∼100 K, it was identified the Gd 5 Si 4 -orthorhombic phase (type I) for both samples. At ∼298 K, it was identified a Gd 5 Si 2 Ge 2 -monoclinic phase, for x = 0.23 and a Sm 5 Sn 4 -orthorhombic phase (type II), for x 0.40. The Rietveld analysis of XRD data suggests a first order magneto-structural transition at Curie temperature for both compositions. Moessbauer results are well consistent with the proposed crystallographic models for these systems.

Global crystallographic textures obtained by neutron and synchrotron radiation

International Nuclear Information System (INIS)

Brokmeier, Heinz-Guenter

2006-01-01

Global crystallographic textures belong to the main characteristic parameters of engineering materials. The global crystallographic texture is always the average texture of a well-defined sample volume which is representative to solve practical engineering problems. Thus a beam having a high penetration power is needed available as neutron or high energetic X-ray radiation. Texture type and texture sharpness are of great importance for materials properties such as the deep drawing behaviour, one of the basic techniques in many industries. Advantages and disadvantages of both radiations make them complementary for measuring crystallographic textures in a wide range of materials

X-ray structure determination and deuteration of nattokinase

International Nuclear Information System (INIS)

Yanagisawa, Yasuhide; Chatake, Toshiyuki; Naito, Sawa; Ohsugi, Tadanori; Yatagai, Chieko; Sumi, Hiroyuki; Kawaguchi, Akio; Chiba-Kamosida, Kaori; Ogawa, Megumi; Adachi, Tatsumi; Morimoto, Yukio

2013-01-01

X-ray structure determination and deuteration of nattokinase were performed to facilitate neutron crystallographic analysis. Nattokinase (NK) is a strong fibrinolytic enzyme, which is produced in abundance by Bacillus subtilis natto. Although NK is a member of the subtilisin family, it displays different substrate specificity when compared with other subtilisins. The results of molecular simulations predict that hydrogen arrangements around Ser221 at the active site probably account for the substrate specificity of NK. Therefore, neutron crystallographic analysis should provide valuable information that reveals the enzymatic mechanism of NK. In this report, the X-ray structure of the non-hydrogen form of undeuterated NK was determined, and the preparation of deuterated NK was successfully achieved. The non-hydrogen NK structure was determined at 1.74 Å resolution. The three-dimensional structures of NK and subtilisin E from Bacillus subtilis DB104 are near identical. Deuteration of NK was carried out by cultivating Bacillus subtilis natto in deuterated medium. The D 2 O resistant strain of Bacillus subtilis natto was obtained by successive cultivation rounds, in which the concentration of D 2 O in the medium was gradually increased. NK was purified from the culture medium and its activity was confirmed by the fibrin plate method. The results lay the framework for neutron protein crystallography analysis

Microstructure Analysis of Bismuth Absorbers for Transition-Edge Sensor X-ray Microcalorimeters

Science.gov (United States)

Yan, Daikang; Divan, Ralu; Gades, Lisa M.; Kenesei, Peter; Madden, Timothy J.; Miceli, Antonino; Park, Jun-Sang; Patel, Umeshkumar M.; Quaranta, Orlando; Sharma, Hemant; Bennett, Douglas A.; Doriese, William B.; Fowler, Joseph W.; Gard, Johnathon D.; Hays-Wehle, James P.; Morgan, Kelsey M.; Schmidt, Daniel R.; Swetz, Daniel S.; Ullom, Joel N.

2018-03-01

Given its large X-ray stopping power and low specific heat capacity, bismuth (Bi) is a promising absorber material for X-ray microcalorimeters and has been used with transition-edge sensors (TESs) in the past. However, distinct X-ray spectral features have been observed in TESs with Bi absorbers deposited with different techniques. Evaporated Bi absorbers are widely reported to have non-Gaussian low-energy tails, while electroplated ones do not show this feature. In this study, we fabricated Bi absorbers with these two methods and performed microstructure analysis using scanning electron microscopy and X-ray diffraction microscopy. The two types of material showed the same crystallographic structure, but the grain size of the electroplated Bi was about 40 times larger than that of the evaporated Bi. This distinction in grain size is likely to be the cause of their different spectral responses.

Identification of inversion domains in KTiOPO{sub 4}via resonant X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Fabrizi, Federica, E-mail: federica.fabrizi@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE (United Kingdom); Thomas, Pamela A. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Nisbet, Gareth; Collins, Stephen P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE (United Kingdom)

2015-05-14

The identification and high-resolution mapping of the absolute crystallographic structure in multi-domain ferroelectric KTiOPO{sub 4} is achieved through a novel synchrotron X-ray diffraction method. On a single Bragg reflection, the intensity ratio in resonant diffraction below and above the Ti absorption K edge demonstrates a domain contrast up to a factor of ∼270, thus implementing a non-contact, non-destructive imaging technique with micrometre spatial resolution, applicable to samples of arbitrarily large dimensions. A novel method is presented for the identification of the absolute crystallographic structure in multi-domain polar materials such as ferroelectric KTiOPO{sub 4}. Resonant (or ‘anomalous’) X-ray diffraction spectra collected across the absorption K edge of Ti (4.966 keV) on a single Bragg reflection demonstrate a huge intensity ratio above and below the edge, providing a polar domain contrast of ∼270. This allows one to map the spatial domain distribution in a periodically inverted sample, with a resolution of ∼1 µm achieved with a microfocused beam. This non-contact, non-destructive technique is well suited for samples of large dimensions (in contrast with traditional resonant X-ray methods based on diffraction from Friedel pairs), and its potential is particularly relevant in the context of physical phenomena connected with an absence of inversion symmetry, which require characterization of the underlying absolute atomic structure (such as in the case of magnetoelectric coupling and multiferroics)

Monte Carlo Simulations of High-speed, Time-gated MCP-based X-ray Detectors: Saturation Effects in DC and Pulsed Modes and Detector Dynamic Range

International Nuclear Information System (INIS)

Kruschwitz, Craig; Ming Wu; Moy, Ken; Rochau, Greg

2008-01-01

We present here results of continued efforts to understand the performance of microchannel plate (MCP)-based, high-speed, gated, x-ray detectors. This work involves the continued improvement of a Monte Carlo simulation code to describe MCP performance coupled with experimental efforts to better characterize such detectors. Our goal is a quantitative description of MCP saturation behavior in both static and pulsed modes. We have developed a new model of charge buildup on the walls of the MCP channels and measured its effect on MCP gain. The results are compared to experimental data obtained with a short-pulse, high-intensity ultraviolet laser; these results clearly demonstrate MCP saturation behavior in both DC and pulsed modes. The simulations compare favorably to the experimental results. The dynamic range of the detectors in pulsed operation is of particular interest when fielding an MCP-based camera. By adjusting the laser flux we study the linear range of the camera. These results, too, are compared to our simulations

X-Ray and Near-Infrared Spectroscopy of Dim X-Ray Point Sources Constituting the Galactic Ridge X-Ray Emission

Directory of Open Access Journals (Sweden)

Kumiko Morihana

2014-12-01

Full Text Available We present the results of X-ray and Near-Infrared observations of the Galactic Ridge X-ray Emission (GRXE. We extracted 2,002 X-ray point sources in the Chandra Bulge Field (l =0°.113, b = 1°.424 down to ~10-14.8 ergscm-2s-1 in 2-8 keV band with the longest observation (900 ks of the GRXE. Based on X-ray brightness and hardness, we classied the X-ray point sources into three groups: A (hard, B (soft and broad spectrum, and C (soft and peaked spectrum. In order to know populations of the X-ray point sources, we carried out NIR imaging and spectroscopy observation. We identied 11% of X-ray point sources with NIR and extracted NIR spectra for some of them. Based on X-ray and NIR properties, we concluded that non-thermal sources in the group A are mostly active galactic nuclei and the thermal sources are mostly white dwarf binaries such as cataclysmic variables (CVs and Pre-CVs. We concluded that the group B and C sources are X-ray active stars in flare and quiescence, respectively.

X-ray diffraction studies of the structure and orientations of thiophene and fluorenone based molecule

International Nuclear Information System (INIS)

Porzio, William; Pasini, Mariacecilia; Destri, Silvia; Giovanella, Umberto; Fontaine, Philippe

2006-01-01

The crystal structure of a conjugated molecule containing thiophene and fluorenone residues has been determined from powder X-ray diffraction (XRD). Thin films ( -5 Pa) onto oxidized silicon substrates, are oriented along with different crystallographic directions. A comparison of XRD in both Grazing Incidence and Bragg-Brentano geometries allowed to perform a quantitative analysis of the various orientations. This approach is generally applicable in the case of multi-oriented films. The results fully account for the poor performance of this molecule in p-type field effect transistor devices

The interchangeability of radioisotope and X-ray based measurements of bone mineral density

International Nuclear Information System (INIS)

Adachi, J.D.; Webber, C.E.

1991-01-01

Lumbar spine and femoral neck bone mineral density (BMD) were measured with a Novo radioisotope based dual photon densitometer and with a Lunar X-ray densitometer in 94 subjects attending a Metabolic Bone Disease Clinic. There was a strong correlation between results obtained from each machine. The correlation coefficients for the spine and femoral neck were 0.97 and 0.88, respectively. Differences between results from each machine were normally distributed with a mean bias of 37.5% (spine) and 27.8% (femur), arising principally from differences in machine calibration. In each case the BMD was greater measured by X-ray absorptiometry. The range for the bias was approximately 25-50% for the spine and 10-45% for the femoral neck. The results from these two machines are not interchangeable. When subjects participating in long term studies using a radioisotope densitometer are transferred to an X-ray densitometer, an individual conversion factor must be measured at each site for each subject. (author)

Crystallization and preliminary X-ray crystallographic analysis of dioscorin from Dioscorea japonica

International Nuclear Information System (INIS)

Xue, You-Lin; Miyakawa, Takuya; Sawano, Yoriko; Tanokura, Masaru

2012-01-01

Dioscorin from D. japonica was expressed, purified and crystallized using the sitting-drop vapour-diffusion method. The dioscorin crystal diffracted X-rays to 2.11 Å resolution. Dioscorin, the major tuber storage protein in yam, has been reported to possess carbonic anhydrase, trypsin inhibitor, angiotensin-converting enzyme (ACE) inhibitor, free-radical scavenger, dehydroascorbate reductase and monodehydroascorbate reductase activities. Recent research has also found that dioscorin can enhance immune modulation via the toll-like receptor 4 (TLR-4) signal transduction pathway in RAW 264.7 cells, murine bone-marrow cells and human monocytes ex vivo. Resolving the structure of dioscorin would help in better understanding its activities and would provide clues to understanding the mechanism of its multiple functions. The full-length protein (residues 1–246) with an additional His 6 tag at the N-terminus was expressed in Escherichia coli Rosetta (DE3) cells. After His-tag cleavage and purification, the protein was crystallized by the sitting-drop vapour-diffusion method at 278 K. An X-ray diffraction data set was collected to a resolution of 2.11 Å using a synchrotron X-ray source. The crystal belonged to space group C222 1 , with unit-cell parameters a = 83.5, b = 156.8, c = 83.6 Å, and was estimated to contain two protein molecules per asymmetric unit

Stellar X-Ray Polarimetry

Science.gov (United States)

Swank, J.

2011-01-01

Most of the stellar end-state black holes, pulsars, and white dwarfs that are X-ray sources should have polarized X-ray fluxes. The degree will depend on the relative contributions of the unresolved structures. Fluxes from accretion disks and accretion disk corona may be polarized by scattering. Beams and jets may have contributions of polarized emission in strong magnetic fields. The Gravity and Extreme Magnetism Small Explorer (GEMS) will study the effects on polarization of strong gravity of black holes and strong magnetism of neutron stars. Some part of the flux from compact stars accreting from companion stars has been reflected from the companion, its wind, or accretion streams. Polarization of this component is a potential tool for studying the structure of the gas in these binary systems. Polarization due to scattering can also be present in X-ray emission from white dwarf binaries and binary normal stars such as RS CVn stars and colliding wind sources like Eta Car. Normal late type stars may have polarized flux from coronal flares. But X-ray polarization sensitivity is not at the level needed for single early type stars.

Exploring the X-Ray Universe

Science.gov (United States)

Seward, Frederick D.; Charles, Philip A.

1995-11-01

Exploring the X-Ray Universe describes the view of the stars and galaxies that is obtained through X-ray telescopes. X-rays, which are invisible to human sight, are created in the cores of active galaxies, in cataclysmic stellar explosions, and in streams of gas expelled by the Sun and stars. The window on the heavens used by the X-ray astronomers shows the great drama of cosmic violence on the grandest scale. This account of X-ray astronomy incorporates the latest findings from several observatories operating in space. These include the Einstein Observatory operated by NASA, and the EXOSAT satellite of the European Space Agency. The book covers the entire field, with chapters on stars, supernova remnants, normal and active galaxies, clusters of galaxies, the diffuse X-ray background, and much more. The authors review basic principles, include the necessary historical background, and explain exactly what we know from X-ray observations of the Universe.

Do protons and X-rays induce cell-killing in human peripheral blood lymphocytes by different mechanisms?

Science.gov (United States)

Miszczyk, J; Rawojć, K; Panek, A; Borkowska, A; Prasanna, P G S; Ahmed, M M; Swakoń, J; Gałaś, A

2018-02-01

Significant progress has been made in the technological and physical aspects of dose delivery and distribution in proton therapy. However, mode of cell killing induced by protons is less understood in comparison with X-rays. The purpose of this study is to see if there is any difference in the mode of cell-killing, induced by protons and X-rays in an ex vivo human peripheral blood lymphocyte (HPBL) model. HPBL were irradiated with 60 MeV proton beam or 250-kVp X-rays in the dose range of 0.3-4.0 Gy. Frequency of apoptotic and necrotic cells was determined by the Fluorescein (FITC)-Annexin V labelling procedure, 1 and 4 h after irradiation. Chip-based DNA Ladder Assay was used to confirm radiation-induced apoptosis and necrosis. Chip-based DNA Ladder Assay was used to confirm radiation-induced apoptosis. Ex vivo irradiation of HPBL with proton beams of 60 MeV or 250 kVp X-rays resulted in apoptotic as well as necrotic modes of cell-killing, which were evident at both 1 and 4 h after irradiation in the whole dose and time range. Generally, our results indicated that protons cause relatively higher yields of cell death that appears to be necrosis compared to X-rays. The analysis also demonstrates that radiation type and dose play a critical role in mode of cell-killing. Obtained results suggest that X-rays and protons induce cell-killing by different modes. Such differences in cell-killing modes may have implications on the potential of a given therapeutic modality to cause immune modulation via programmed cell death (X-rays) or necrotic cell death (proton therapy). These studies point towards exploring for gene expression biomarkers related necrosis or apoptosis to predict immune response after proton therapy.

Statistical analysis of the Einstein normal galaxy sample. III. Radio and X-ray properties of elliptical and S0 galaxies

International Nuclear Information System (INIS)

Fabbiano, G.; Klein, U.; Trinchieri, G.; Wielebinski, R.; Bonn Universitaet, West Germany; Arcetri, Osservatorio Astrofisico, Florence, Italy; Max-Planck-Institut fuer Radioastronomie, Bonn, West Germany)

1987-01-01

Radioastronomy, optical and X-ray data were used to probe the cause of high X-ray luminosities of 28 radio-quiet elliptical galaxies (RQE) and S0 galaxies previously scanned by the Einstein Observatory. Comparisons were made with similar data on double-lobed 3CR galaxies. Radio luminosities were highly correlated with the X-ray luminosities, agreeing with models of radio nuclear sources in early-type galaxies as accreting compact objects. Additionally, 3CR galaxies seemed to be large-scale versions of normal RQE. The significance of interstellar medium/intracluster medium interactions for high correlations between the core and total radio power from X-ray emitting galaxies is discussed. 54 references

Normal murine bone morphometry: a comparison of magnetic resonance microscopy with micro X-ray and histology

International Nuclear Information System (INIS)

Weber, Michael H.; Sharp, Jonathan C.; Hassard, Thomas H.; Orr, William F.

2002-01-01

Objective: The authors have devised a means to assess subtle changes in the structure of bone using magnetic resonance (MR) microscopy. MR microscopy was compared with micro X-ray and histology to analyze the structure of normal bone. Design: Femurs of C57Bl/6 mice were examined ex vivo using differently orientated slices and pulse sequences on both a 9.4 and 11.7 T MR scanner, followed by micro X-ray and histology. A thresholding analysis technique was applied to MR images, to generate contour lines delineating the boundaries between bone and marrow. Results: By MR microscopy, optimal correlation with histological ''gold standards'' was obtained using a longitudinal sectional versus a cross-sectional slice profile, a short echo time gradient-echo sequence versus a long echo time spin-echo sequence, and a higher field strength, 11.7 T versus 9.4 T. Gradient-echo images at 11.7 T were acquired with a maximum in-plane resolution of 35 μm. Conclusion: Our results demonstrate that the percent area of marrow increases and percent area of trabecular bone and cortical bone thickness decreases on moving from the epiphyseal growth plate to the diaphysis. These changes observed with MR microscopy correlate with the histological data, but did not correlate with micro X-ray data, which showed no trends. Our quantitative evaluation using MR microscopy was found to be an effective means to visualize the normal variation in bone microanatomy compared with a histological ''gold standard'', and was a superior means of quantification in comparison with micro X-ray. (orig.)

Crystallographic properties of fertilizer compounds

Energy Technology Data Exchange (ETDEWEB)

Frazier, A.W.; Dillard, E.F.; Thrasher, R.D.; Waerstad, K.R.; Hunter, S.R.; Kohler, J.J.; Scheib, R.M.

1991-02-01

This bulletin is a compilation of crystallographic data collected at NFERC on 450 fertilizer-related compounds. In TVA's fertilizer R and D program, petrographic examination, XRD, and infrared spectroscopy are combined with conventional chemical analysis methods in identifying the individual compounds that occur in fertilizer materials. This handbook brings together the results of these characterization studies and supplemental crystallographic data from the literature. It is in one-compound-per-page, loose-leaf format, ordered alphabetically by IUPAC name. Indexes provided include IUPAC name, formula, group, alternate formula, synonyms, x-ray data, optical data. Tables are given for solids, compounds in commercial MAP and DAP, and matrix materials in phosphate rock.

Sources of the X-rays Based on Compton Scattering

International Nuclear Information System (INIS)

Androsov, V.; Bulyak, E.; Gladkikh, P.; Karnaukhov, I.; Mytsykov, A.; Telegin, Yu.; Shcherbakov, A.; Zelinsky, A.

2007-01-01

The principles of the intense X-rays generation by laser beam scattering on a relativistic electron beam are described and description of facilities assigned to produce the X-rays based on Compton scattering is presented. The possibilities of various types of such facilities are estimated and discussed. The source of the X-rays based on a storage ring with low beam energy is described in details and advantages of the sources of such type are discussed.The results of calculation and numerical simulation carried out for laser electron storage ring NESTOR that is under development in NSC KIPT show wide prospects of the accelerator facility of such type

Phase-contrast X-ray CT

Energy Technology Data Exchange (ETDEWEB)

Momose, Atsushi [Hitachi Ltd., Saitama (Japan). Advanced Research Laboratory; Takeda, Tohoru; Itai, Yuji

1995-12-01

Phase-contrast X-ray computed tomography (CT) enabling the observation of biological soft tissues without contrast enhancement has been developed. The X-ray phase shift caused by an object is measured and input to a standard CT reconstruction algorithm. A thousand times increase in the image sensitivity to soft tissues is achieved compared with the conventional CT using absorption contrast. This is because the X-ray phase shift cross section of light elements is about a thousand times larger than the absorption cross section. The phase shift is detected using an X-ray interferometer and computer analyses of interference patterns. Experiments were performed using a synchrotron X-ray source. Excellent image sensitivity is demonstrated in the observation of cancerous rabbit liver. The CT images distinguish cancer lesion from normal liver tissue and, moreover, visualize the pathological condition in the lesion. Although the X-ray energy employed and the present observation area size are not suitable for medical applications as they are, phase-contrast X-ray CT is promising for investigating the internal structure of soft tissue which is almost transparent for X-rays. The high sensitivity also provides the advantage of reducing X-ray doses. (author).

X-ray crystallographic structure determination of the smoke-derived karrikin KAR3

Czech Academy of Sciences Publication Activity Database

Nair, J. J.; Munro, O. Q.; Pošta, Martin; Papenfus, H. B.; Beier, Petr; van Staden, J.

2013-01-01

Roč. 88, September (2013), s. 107-109 ISSN 0254-6299 Institutional support: RVO:61388963 Keywords : germination * karrikin * plant growth regulator * smoke * X-ray Subject RIV: CC - Organic Chemistry Impact factor: 1.340, year: 2013

A Catalog of Candidate Intermediate-Luminosity X-Ray Objects

Science.gov (United States)

Colbert, E. J. M.; Ptak, A. F.

2002-11-01

ROSAT, and now Chandra, X-ray images allow studies of extranuclear X-ray point sources in galaxies other than our own. X-ray observations of normal galaxies with ROSAT and Chandra have revealed that off-nuclear, compact, intermediate-luminosity (LX[2-10keV]>=1039.0 ergs s-1) X-ray objects (IXOs, a.k.a. ULXs [ultraluminous X-ray sources]) are quite common. Here we present a catalog and finding charts for 87 IXOs in 54 galaxies, derived from all of the ROSAT HRI imaging data for galaxies with cz<=5000 km s-1 from the Third Reference Catalog of Bright Galaxies. We have defined the cutoff LX for IXOs so that it is well above the Eddington luminosity of a 1.4 Msolar black hole (1038.3 ergs s-1), so as not to confuse IXOs with ``normal'' black hole X-ray binaries. This catalog is intended to provide a baseline for follow-up work with Chandra and XMM-Newton, and with space- and ground-based survey work at wavelengths other than X-ray. We demonstrate that elliptical galaxies with IXOs have a larger number of IXOs per galaxy than nonelliptical galaxies with IXOs and note that they are not likely to be merely high-mass X-ray binaries with beamed X-ray emission, as may be the case for IXOs in starburst galaxies. Approximately half of the IXOs with multiple observations show X-ray variability, and many (19) of the IXOs have faint optical counterparts in DSS optical B-band images. Follow-up observations of these objects should be helpful in identifying their nature.

Legal directives in the X-ray regulation for the field of X-ray diagnostics; Rechtsvorschriften der Roentgenverordnung fuer den Bereich der Roentgendiagnostik

Energy Technology Data Exchange (ETDEWEB)

Huhn, Walter [Ministerium fuer Arbeit, Integration und Soziales des Landes Nordrhein-Westfalen, Duesseldorf (Germany)

2012-11-01

The operation of each X-ray device is subject to the requirements of the X-ray regulations (RoeV); for different operational modes or applications like curative diagnostics, X-ray serial examinations, X-ray radiotherapy and teleradiology different directives exist and have to be respected. The report discusses the issues licensing and notification procedures, radiation protection representative, requirements for the commissioning (teleradiology, serial X.ray examinations), technical qualification and radiation protection knowledge of physicians, technical qualification of the assistant personnel.

Standard test method for determining the effective elastic parameter for X-ray diffraction measurements of residual stress

CERN Document Server

American Society for Testing and Materials. Philadelphia

1998-01-01

1.1 This test method covers a procedure for experimentally determining the effective elastic parameter, Eeff, for the evaluation of residual and applied stresses by X-ray diffraction techniques. The effective elastic parameter relates macroscopic stress to the strain measured in a particular crystallographic direction in polycrystalline samples. Eeff should not be confused with E, the modulus of elasticity. Rather, it is nominally equivalent to E/(1 + ν) for the particular crystallographic direction, where ν is Poisson's ratio. The effective elastic parameter is influenced by elastic anisotropy and preferred orientation of the sample material. 1.2 This test method is applicable to all X-ray diffraction instruments intended for measurements of macroscopic residual stress that use measurements of the positions of the diffraction peaks in the high back-reflection region to determine changes in lattice spacing. 1.3 This test method is applicable to all X-ray diffraction techniques for residual stress measurem...

Source of X-ray radiation based on back compton scattering

CERN Document Server

Bulyak, E V; Karnaukhov, I M; Kononenko, S G; Lapshin, V G; Mytsykov, A O; Telegin, Yu P; Shcherbakov, A A; Zelinsky, Andrey Yurij

2000-01-01

Applicability was studied and previous estimation was done of power X-ray beams generation by backward Compton scattering of a laser photon beam on a cooled down electron beam. The few MeV electron beam circulating in a compact storage ring can be cooled down by interaction of that beam with powerful laser radiation of micrometer wavelength to achieve normalized emittance of 10 sup - sup 7 m. A tunable X-ray source of photons of energy ranging from few keV up to a hundred keV could result from the interaction of the laser beam with a dense electron beam.

Source of X-ray radiation based on back compton scattering

Energy Technology Data Exchange (ETDEWEB)

Bulyak, E.V.; Gladkikh, P.I.; Karnaukhov, I.M.; Kononenko, S.G.; Lapshin, V.I.; Mytsykov, A.O.; Telegin, Yu.N.; Shcherbakov, A.A. E-mail: shcherbakov@kipt.kharkov.ua; Zelinsky, A.Yu

2000-06-21

Applicability was studied and previous estimation was done of power X-ray beams generation by backward Compton scattering of a laser photon beam on a cooled down electron beam. The few MeV electron beam circulating in a compact storage ring can be cooled down by interaction of that beam with powerful laser radiation of micrometer wavelength to achieve normalized emittance of 10{sup -7} m. A tunable X-ray source of photons of energy ranging from few keV up to a hundred keV could result from the interaction of the laser beam with a dense electron beam.

Source of X-ray radiation based on back compton scattering

International Nuclear Information System (INIS)

Bulyak, E.V.; Gladkikh, P.I.; Karnaukhov, I.M.; Kononenko, S.G.; Lapshin, V.I.; Mytsykov, A.O.; Telegin, Yu.N.; Shcherbakov, A.A.; Zelinsky, A.Yu.

2000-01-01

Applicability was studied and previous estimation was done of power X-ray beams generation by backward Compton scattering of a laser photon beam on a cooled down electron beam. The few MeV electron beam circulating in a compact storage ring can be cooled down by interaction of that beam with powerful laser radiation of micrometer wavelength to achieve normalized emittance of 10 -7 m. A tunable X-ray source of photons of energy ranging from few keV up to a hundred keV could result from the interaction of the laser beam with a dense electron beam

X-ray optics and X-ray microscopes: new challenges

International Nuclear Information System (INIS)

Susini, J.

2004-01-01

Soon after the discovery of X-rays in 1895 by W. Roentgen, it became rapidly clear that the methods traditionally used in the visible light regime, namely refraction, diffraction and reflection were difficult to apply for X-ray optics. The physical origins of these difficulties are closely linked to the very nature of interaction of X-rays with matter. The small deviation δ of the refractive index of condensed matter from unity makes it difficult to extend refraction-based optics from the optical spectral region to the X-ray region because the refraction angle is proportional to δ. Similarly it is very challenging to extend diffraction-based focusing techniques to X-rays because the diffraction angle scales inversely with wavelength. Finally, the use of reflection-based optics is also limited by the very small critical angle for total reflection. All those fundamental limitations prevented for almost one century, the development of X-ray microscopy whereas electron microscopy became a standard tool. In the past twenty years, interests for X-ray microscopy revived, mainly because of several major advances in X-ray sources and X-ray optics. X-ray microscopy techniques are now emerging as powerful and complementary tools for submicron investigations. Soft X-ray microscopes offer traditionally the possibility to form direct images of thick hydrated biological material in near-native environment, at a spatial resolution well beyond that achievable with visible light microscopy. Natural contrast is available in the soft X-ray region, in the so-called ''water-window'', due to the presence of absorption edges of the major constituents (C,N,O). Recent advances in manufacturing techniques have enlarged the accessible energy range of micro-focussing optics and offer new applications in a broad range of disciplines. X-ray microscopy in the 1 - 30 keV energy range is better suited for fluorescence to map trace elements, tomography for 3D imaging and micro-diffraction. The

A Hard X-Ray Power-Law Spectral Cutoff in Centaurus X-4

DEFF Research Database (Denmark)

Chakrabarty, Deepto; Tomsick, John A.; Grefenstette, Brian W.

2015-01-01

The low-mass X-ray binary Cen X-4 is the brightest and closest (<1.2 kpc) quiescent neutron star transient. Previous 0.5-10 keV X-ray observations of Cen X-4 in quiescence identified two spectral components: soft thermal emission from the neutron star atmosphere and a hard power-law tail of unkno...... behavior with PSR J1023+0038, IGR J18245-2452, and XSS J12270-4859, which have shown transitions between LMXB and radio pulsar modes at a similar X-ray luminosity....

Simulation and application of micro X-ray fluorescence based on an ellipsoidal capillary

Energy Technology Data Exchange (ETDEWEB)

Yang, Jing; Li, Yude; Wang, Xingyi; Zhang, Xiaoyun; Lin, Xiaoyan, E-mail: yangjing_928@126.com

2017-06-15

Highlights: • A micro X-ray fluorescence setup based on an ellipsoidal capillary was presented. • The optimal parameters of ellipsoidal capillary were designed. • The 2D mapping image of biological sample was obtained. - Abstract: A micro X-ray fluorescence setup was presented, based on an ellipsoidal capillary and a traditional laboratorial X-ray source. Using Ray-tracing principle, we have simulated the transmission path of X-ray beam in the ellipsoidal capillary and designed the optimal parameters of the ellipsoidal capillary for the micro X-ray fluorescence setup. We demonstrate that ellipsoidal capillary is well suited as condenser for the micro X-ray fluorescence based on traditional laboratorial X-ray source. Furthermore, we obtain the 2D mapping image of the leaf blade sample by using the ellipsoidal capillary we designed.

Technological Challenges to X-Ray FELs

Energy Technology Data Exchange (ETDEWEB)

Nuhn, Heinz-Dieter

1999-09-16

There is strong interest in the development of x-ray free electron lasers (x-ray FELs). The interest is driven by the scientific opportunities provided by intense, coherent x-rays. An x-ray FEL has all the characteristics of a fourth-generation source: brightness several orders of magnitude greater than presently achieved in third-generation sources, full transverse coherence, and sub-picosecond long pulses. The SLAC and DESY laboratories have presented detailed design studies for X-Ray FEL user facilities around the 0.1 nm wavelength-regime (LCLS at SLAC, TESLA X-Ray FEL at DESY). Both laboratories are engaged in proof-of-principle experiments are longer wavelengths (TTF FEL Phase I at 71 nm, VISA at 600-800 nm) with results expected in 1999. The technologies needed to achieve the proposed performances are those of bright electron sources, of acceleration systems capable of preserving the brightness of the source, and of undulators capable of meeting the magnetic and mechanical tolerances that are required for operation in the SASE mode. This paper discusses the technological challenges presented by the X-Ray FEL projects.

Dependence of the K x-ray energy on the mode of excitation

International Nuclear Information System (INIS)

Wang, K.C.; Boehm, F.; Hahn, A.A.; Vogel, P.

1977-01-01

The energy shifts in the Ta K x rays resulting from the K-capture of 181 W, fluorescence of Ta, and β - decay of 181 Hf followed by internal conversion in 181 Ta are reported. Both W metal and WO 3 on one hand, and Ta metal and Ta 2 O 5 on the other hand, were used. Comparison of the K x-ray energies of the K-capture sources 153 Gd (Eu x rays) and 175 Hf (Lu x rays) and the corresponding fluorescence sources was also made. Various effects which may influence the K x-ray energies are discussed. 9 references

Identification of N-ethylmethylamine as a novel scaffold for inhibitors of soluble epoxide hydrolase by crystallographic fragment screening.

Science.gov (United States)

Amano, Yasushi; Tanabe, Eiki; Yamaguchi, Tomohiko

2015-05-15

Soluble epoxide hydrolase (sEH) is a potential target for the treatment of inflammation and hypertension. X-ray crystallographic fragment screening was used to identify fragment hits and their binding modes. Eight fragment hits were identified via soaking of sEH crystals with fragment cocktails, and the co-crystal structures of these hits were determined via individual soaking. Based on the binding mode, N-ethylmethylamine was identified as a promising scaffold that forms hydrogen bonds with the catalytic residues of sEH, Asp335, Tyr383, and Tyr466. Compounds containing this scaffold were selected from an in-house chemical library and assayed. Although the starting fragment had a weak inhibitory activity (IC50: 800μM), we identified potent inhibitors including 2-({[2-(adamantan-1-yl)ethyl]amino}methyl)phenol exhibiting the highest inhibitory activity (IC50: 0.51μM). This corresponded to a more than 1500-fold increase in inhibitory activity compared to the starting fragment. Co-crystal structures of the hit compounds demonstrate that the binding of N-ethylmethylamine to catalytic residues is similar to that of the starting fragment. We therefore consider crystallographic fragment screening to be appropriate for the identification of weak but promising fragment hits. Copyright © 2015 Elsevier Ltd. All rights reserved.

Normalized modes at selected points without normalization

Science.gov (United States)

Kausel, Eduardo

2018-04-01

As every textbook on linear algebra demonstrates, the eigenvectors for the general eigenvalue problem | K - λM | = 0 involving two real, symmetric, positive definite matrices K , M satisfy some well-defined orthogonality conditions. Equally well-known is the fact that those eigenvectors can be normalized so that their modal mass μ =ϕT Mϕ is unity: it suffices to divide each unscaled mode by the square root of the modal mass. Thus, the normalization is the result of an explicit calculation applied to the modes after they were obtained by some means. However, we show herein that the normalized modes are not merely convenient forms of scaling, but that they are actually intrinsic properties of the pair of matrices K , M, that is, the matrices already "know" about normalization even before the modes have been obtained. This means that we can obtain individual components of the normalized modes directly from the eigenvalue problem, and without needing to obtain either all of the modes or for that matter, any one complete mode. These results are achieved by means of the residue theorem of operational calculus, a finding that is rather remarkable inasmuch as the residues themselves do not make use of any orthogonality conditions or normalization in the first place. It appears that this obscure property connecting the general eigenvalue problem of modal analysis with the residue theorem of operational calculus may have been overlooked up until now, but which has in turn interesting theoretical implications.Á

Simulation and application of micro X-ray fluorescence based on an ellipsoidal capillary

Science.gov (United States)

Yang, Jing; Li, Yude; Wang, Xingyi; Zhang, Xiaoyun; Lin, Xiaoyan

2017-06-01

A micro X-ray fluorescence setup was presented, based on an ellipsoidal capillary and a traditional laboratorial X-ray source. Using Ray-tracing principle, we have simulated the transmission path of X-ray beam in the ellipsoidal capillary and designed the optimal parameters of the ellipsoidal capillary for the micro X-ray fluorescence setup. We demonstrate that ellipsoidal capillary is well suited as condenser for the micro X-ray fluorescence based on traditional laboratorial X-ray source. Furthermore, we obtain the 2D mapping image of the leaf blade sample by using the ellipsoidal capillary we designed.

Development of a micro-X-ray fluorescence system based on polycapillary X-ray optics for non-destructive analysis of archaeological objects

Science.gov (United States)

Cheng, Lin; Ding, Xunliang; Liu, Zhiguo; Pan, Qiuli; Chu, Xuelian

2007-08-01

A new micro-X-ray fluorescence (micro-XRF) system based on rotating anode X-ray generator and polycapillary X-ray optics has been set up in XOL Lab, BNU, China, in order to be used for analysis of archaeological objects. The polycapillary X-ray optics used here can focus the primary X-ray beam down to tens of micrometers in diameter that allows for non-destructive and local analysis of sub-mm samples with minor/trace level sensitivity. The analytical characteristics and potential of this micro-XRF system in archaeological research are discussed. Some described uses of this instrument include studying Chinese ancient porcelain.

Development of a micro-X-ray fluorescence system based on polycapillary X-ray optics for non-destructive analysis of archaeological objects

Energy Technology Data Exchange (ETDEWEB)

Cheng Lin [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing Radiation Center, Beijing, 100875 (China)], E-mail: chenglin@bnu.edu.cn; Ding Xunliang; Liu Zhiguo; Pan Qiuli; Chu Xuelian [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing Radiation Center, Beijing, 100875 (China)

2007-08-15

A new micro-X-ray fluorescence (micro-XRF) system based on rotating anode X-ray generator and polycapillary X-ray optics has been set up in XOL Lab, BNU, China, in order to be used for analysis of archaeological objects. The polycapillary X-ray optics used here can focus the primary X-ray beam down to tens of micrometers in diameter that allows for non-destructive and local analysis of sub-mm samples with minor/trace level sensitivity. The analytical characteristics and potential of this micro-XRF system in archaeological research are discussed. Some described uses of this instrument include studying Chinese ancient porcelain.

X-ray structure determination and deuteration of nattokinase

Energy Technology Data Exchange (ETDEWEB)

Yanagisawa, Yasuhide [Chiba Institute of Science, 15-8 Shiomi-cho, Cho-shi, Chiba 288-025 (Japan); Chatake, Toshiyuki [Kyoto University, Asashironishi 2, Kumatori, Osaka 590-0494 (Japan); Naito, Sawa; Ohsugi, Tadanori; Yatagai, Chieko; Sumi, Hiroyuki [Kurashiki University of Science and the Arts, 2640 Nishinoura, Tsurajima-cho, Kurashiki, Okayama 712-8505 (Japan); Kawaguchi, Akio [Kyoto University, Asashironishi 2, Kumatori, Osaka 590-0494 (Japan); Chiba-Kamosida, Kaori [Nippon Advanced Technology Co. Ltd, J-PARC, 2-4 Shirane Shirakata, Tokai, Ibaraki 319-1195 (Japan); Ogawa, Megumi; Adachi, Tatsumi [Chiba Institute of Science, 15-8 Shiomi-cho, Cho-shi, Chiba 288-025 (Japan); Morimoto, Yukio [Kyoto University, Asashironishi 2, Kumatori, Osaka 590-0494 (Japan)

2013-11-01

X-ray structure determination and deuteration of nattokinase were performed to facilitate neutron crystallographic analysis. Nattokinase (NK) is a strong fibrinolytic enzyme, which is produced in abundance by Bacillus subtilis natto. Although NK is a member of the subtilisin family, it displays different substrate specificity when compared with other subtilisins. The results of molecular simulations predict that hydrogen arrangements around Ser221 at the active site probably account for the substrate specificity of NK. Therefore, neutron crystallographic analysis should provide valuable information that reveals the enzymatic mechanism of NK. In this report, the X-ray structure of the non-hydrogen form of undeuterated NK was determined, and the preparation of deuterated NK was successfully achieved. The non-hydrogen NK structure was determined at 1.74 Å resolution. The three-dimensional structures of NK and subtilisin E from Bacillus subtilis DB104 are near identical. Deuteration of NK was carried out by cultivating Bacillus subtilis natto in deuterated medium. The D{sub 2}O resistant strain of Bacillus subtilis natto was obtained by successive cultivation rounds, in which the concentration of D{sub 2}O in the medium was gradually increased. NK was purified from the culture medium and its activity was confirmed by the fibrin plate method. The results lay the framework for neutron protein crystallography analysis.

Wide field X-ray telescopes: Detecting X-ray transients/afterglows related to gamma ray bursts

International Nuclear Information System (INIS)

Hudec, Rene; Pina, Ladislav; Inneman, Adolf; Gorenstein, Paul; Rezek, Tomas

1999-01-01

The recent discovery of X-ray afterglows of GRBs opens the possibility of analyses of GRBs by their X-ray detections. However, imaging X-ray telescopes in current use mostly have limited field of view. Alternative X-ray optics geometries achieving very large fields of view have been theoretically suggested in the 70ies but not constructed and used so far. We review the geometries and basic properties of the wide-field X-ray optical systems based on one- and two-dimensional lobster-eye geometry and suggest technologies for their development and construction. First results of the development of double replicated X-ray reflecting flats for use in one-dimensional X-ray optics of lobster eye type are presented and discussed. Optimum strategy for locating GRBs upon their X-ray counterparts is also presented and discussed

A statistical analysis of the Einstein normal galaxy sample. III - Radio and X-ray properties of elliptical and S0 galaxies

Science.gov (United States)

Fabbiano, G.; Klein, U.; Trinchieri, G.; Wielebinski, R.

1987-01-01

Radioastronomy, optical and X-ray data were used to probe the cause of high X-ray luminosities of 28 radio-quiet elliptical galaxies (RQE) and S0 galaxies previously scanned by the Einstein Observatory. Comparisons were made with similar data on double-lobed 3CR galaxies. Radio luminosities were highly correlated with the X-ray luminosities, agreeing with models of radio nuclear sources in early-type galaxies as accreting compact objects. Additionally, 3CR galaxies seemed to be large-scale versions of normal RQE. The significance of interstellar medium/intracluster medium interactions for high correlations between the core and total radio power from X-ray emitting galaxies is discussed.

Crystallization and preliminary X-ray crystallographic characterization of TrmFO, a folate-dependent tRNA methyltransferase from Thermotoga maritima

Energy Technology Data Exchange (ETDEWEB)

Cicmil, Nenad, E-mail: cicmil@uiuc.edu [Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2008-03-01

T. maritima TrmFO was overexpressed, purified and crystallized. A diffraction data set was collected to a resolution of 2.6 Å. TrmFO, previously classified as GID, is a methyltransferase that catalyzes the formation of 5-methyluridine or ribothymidine (T) at position 54 in tRNA in some Gram-positive bacteria. To date, TrmFO is the only characterized tRNA methyltransferase that does not use S-adenosylmethionine as the methyl-group donor. Instead, the donor of the methyl group is N{sup 5},N{sup 10}-methylenetetrahydrofolate. The crystallization and preliminary X-ray crystallographic studies of TrmFO are reported here. The recombinant protein, cloned from Thermotoga maritima genomic DNA, was overproduced in Esherichia coli and crystallized in 25%(v/v) PEG 4000, 100 mM NaCl and sodium citrate buffer pH 5.0 at 291 K using the hanging-drop vapor-diffusion method. The plate-shaped crystals diffracted to 2.6 Å and belong to the orthorhombic space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 79.94, b = 92.46, c = 127.20 Å.

Modelling and simulation of multi-phase effects on X-ray elasticity constants

CERN Document Server

Freour, S; Guillen, R; François, M X

2003-01-01

This paper deals with the calculation of X-ray Elasticity Constants (XEC) of phases embedded in multi-phase polycrystals. A three scales (macroscopic, pseudo-macroscopic, mesoscopic) model based on the classical self-consistent formalism is developed in order to analyse multi-phase effects on XEC values. Simulations are performed for cubic or hexagonal crystallographic structure phases embedded in several two-phases materials. In fact, it is demonstrated that XEC vary with the macroscopic stiffness of the whole polycrystal. In consequence, the constants of one particular phase depend on the elastic behaviour and the volume fraction of all the phases constituting the material. Now, XEC play a leading role in pseudo-macroscopic stresses determination by X-Ray Diffraction (XRD) methods. In this work, a quantitative analysis of the multi-phase effects on stresses determination by XRD methods was performed. Numerical results will be compared and discussed. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Chemical crystallography with pulsed neutrons and synchrotron x-rays

International Nuclear Information System (INIS)

Carrondo, M.A.; Jeffrey, G.A.

1988-01-01

Solid-state chemists and physicists, crystallographers and molecular biologists who are using or who plan to use the special properties of pulsed neutron spallation and synchrotron X-ray sources will find this book invaluable. Those scientists who have not yet gained experience in working with such sources will find the basic physics of the radiations, their production and their scattering properties explained, together with descriptions of the different types of diffraction experiments which use them

Covering complete proteomes with X-ray structures: a current snapshot

Energy Technology Data Exchange (ETDEWEB)

Mizianty, Marcin J.; Fan, Xiao; Yan, Jing; Chalmers, Eric; Woloschuk, Christopher [University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Joachimiak, Andrzej, E-mail: andrzejj@anl.gov [Argonne National Laboratory, Argonne, IL 60439 (United States); Kurgan, Lukasz, E-mail: andrzejj@anl.gov [University of Alberta, Edmonton, Alberta T6G 2V4 (Canada)

2014-11-01

The current and the attainable coverage by X-ray structures of proteins and their functions on the scale of the ‘protein universe’ are estimated. A detailed analysis of the coverage across nearly 2000 proteomes from all superkingdoms of life and functional annotations is performed, with particular focus on the human proteome and the family of GPCR proteins. Structural genomics programs have developed and applied structure-determination pipelines to a wide range of protein targets, facilitating the visualization of macromolecular interactions and the understanding of their molecular and biochemical functions. The fundamental question of whether three-dimensional structures of all proteins and all functional annotations can be determined using X-ray crystallography is investigated. A first-of-its-kind large-scale analysis of crystallization propensity for all proteins encoded in 1953 fully sequenced genomes was performed. It is shown that current X-ray crystallographic knowhow combined with homology modeling can provide structures for 25% of modeling families (protein clusters for which structural models can be obtained through homology modeling), with at least one structural model produced for each Gene Ontology functional annotation. The coverage varies between superkingdoms, with 19% for eukaryotes, 35% for bacteria and 49% for archaea, and with those of viruses following the coverage values of their hosts. It is shown that the crystallization propensities of proteomes from the taxonomic superkingdoms are distinct. The use of knowledge-based target selection is shown to substantially increase the ability to produce X-ray structures. It is demonstrated that the human proteome has one of the highest attainable coverage values among eukaryotes, and GPCR membrane proteins suitable for X-ray structure determination were determined.

Covering complete proteomes with X-ray structures: a current snapshot

International Nuclear Information System (INIS)

Mizianty, Marcin J.; Fan, Xiao; Yan, Jing; Chalmers, Eric; Woloschuk, Christopher; Joachimiak, Andrzej; Kurgan, Lukasz

2014-01-01

The current and the attainable coverage by X-ray structures of proteins and their functions on the scale of the ‘protein universe’ are estimated. A detailed analysis of the coverage across nearly 2000 proteomes from all superkingdoms of life and functional annotations is performed, with particular focus on the human proteome and the family of GPCR proteins. Structural genomics programs have developed and applied structure-determination pipelines to a wide range of protein targets, facilitating the visualization of macromolecular interactions and the understanding of their molecular and biochemical functions. The fundamental question of whether three-dimensional structures of all proteins and all functional annotations can be determined using X-ray crystallography is investigated. A first-of-its-kind large-scale analysis of crystallization propensity for all proteins encoded in 1953 fully sequenced genomes was performed. It is shown that current X-ray crystallographic knowhow combined with homology modeling can provide structures for 25% of modeling families (protein clusters for which structural models can be obtained through homology modeling), with at least one structural model produced for each Gene Ontology functional annotation. The coverage varies between superkingdoms, with 19% for eukaryotes, 35% for bacteria and 49% for archaea, and with those of viruses following the coverage values of their hosts. It is shown that the crystallization propensities of proteomes from the taxonomic superkingdoms are distinct. The use of knowledge-based target selection is shown to substantially increase the ability to produce X-ray structures. It is demonstrated that the human proteome has one of the highest attainable coverage values among eukaryotes, and GPCR membrane proteins suitable for X-ray structure determination were determined

Nuclear Enhanced X-ray Maximum Entropy Method Used to Analyze Local Distortions in Simple Structures

DEFF Research Database (Denmark)

Christensen, Sebastian; Bindzus, Niels; Christensen, Mogens

We introduce a novel method for reconstructing pseudo nuclear density distributions (NDDs): Nuclear Enhanced X-ray Maximum Entropy Method (NEXMEM). NEXMEM offers an alternative route to experimental NDDs, exploiting the superior quality of synchrotron X-ray data compared to neutron data. The method...... proposed to result from anharmonic phonon scattering or from local fluctuating dipoles on the Pb site.[1,2] No macroscopic symmetry change are associated with these effects, rendering them invisible to conventional crystallographic techniques. For this reason PbX was until recently believed to adopt...

Novel X-ray telescopes for wide-field X-ray monitoring

International Nuclear Information System (INIS)

Hudec, R.; Inneman, A.; Pina, L.; Sveda, L.

2005-01-01

We report on fully innovative very wide-field of view X-ray telescopes with high sensitivity as well as large field of view. The prototypes are very promising, allowing the proposals for space projects with very wide-field Lobster-eye X-ray optics to be considered. The novel telescopes will monitor the sky with unprecedented sensitivity and angular resolution of order of 1 arcmin. They are expected to contribute essentially to study and to understand various astrophysical objects such as AGN, SNe, Gamma-ray bursts (GRBs), X-ray flashes (XRFs), galactic binary sources, stars, CVs, X-ray novae, various transient sources, etc. The Lobster optics based X-ray All Sky Monitor is capable to detect around 20 GRBs and 8 XRFs yearly and this will surely significantly contribute to the related science

Polarisation resonance in X-ray diffraction

International Nuclear Information System (INIS)

Goodman, P.; Paterson, D.; Matheson, S.

1994-01-01

The study of crystal structures by means of dynamic X-ray diffraction has placed a challenge to theoreticians to revise the X-ray diffraction theory based on Maxwell's equation. In this paper the feasibility of using 'polarisation resonance' as a tool in the determination of absolute configuration for asymmetric structures is investigated. Two (left- and right-handed), σ + and σ- , circular polarization states for 3-beam conditions are considered. Moreover, extending interaction into the 3 rd. dimension (normal to the beam) opens the possibility of absolute configuration determination of asymmetric structures in 3 dimensions. The computational scheme used is shown in terms of scattering diagrams. 7 refs., 1 tab., 6 figs

Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

Directory of Open Access Journals (Sweden)

L. Miaja-Avila

2015-03-01

Full Text Available We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ∼106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.

X-ray Excited Optical Fluorescence and Diffraction Imaging of Reactivity and Crystallinity in a Zeolite Crystal : Crystallography and Molecular Spectroscopy in One

NARCIS (Netherlands)

Ristanovic, Zoran; Hofmann, Jan P; Richard, Marie-Ingrid; Jiang, Tao; Chahine, Gilbert A; Schülli, Tobias U; Meirer, Florian; Weckhuysen, Bert M

2016-01-01

Structure-activity relationships in heterogeneous catalysis are challenging to be measured on a single-particle level. For the first time, one X-ray beam is used to determine the crystallographic structure and reactivity of a single zeolite crystal. The method generates μm-resolved X-ray diffraction

Fluctuations on the X-ray intensity beam using a portable X-ray probe based on {sup 6}LiI(Eu) crystal

Energy Technology Data Exchange (ETDEWEB)

Araujo, Geraldo P.; Oliveira, Arno H. [Universidade Federal de Minas Gerais (PCTN/UFMG), Belo Horizonte, MG (Brazil). Programa de Pos-Graduacao em Ciencias e Tecnicas Nucleares; Carneiro, Andre C.; Carneiro, Clemente J.G.; Milian, Felix M.; Velasco, Fermin G., E-mail: fermin@uesc.b [Universidade Estadual de Santa Cruz (CPqCTR/UESC), Ilheus, BA (Brazil). Centro de Pesquisa em Ciencias e Tecnologias das Radiacoes

2011-07-01

X-rays are produced by accelerating electrons with a high voltage and allowing them to collide with a metal target. This high voltage presents fluctuations that define peak, minimum, and average voltages. Different voltages are applied to the X-ray tube depending on the radiographic applications. A rectifier circuit converts the alternating high voltage to unidirectional high voltage to accelerate electrons in this tube. The fluctuations on the energy in the electron beam depend on the mode of rectification. Both energy of the electrons and X rays intensity fluctuates. A portable probe built with a {sup 6}LiI(Eu) detector coupled to a 10 m light guide and a Hamamatsu photon counting head H9319 was used to measuring X ray intensities. This system is designed to collect up to 10000 counts in intervals of 10 ms to 1 s. Counts were accumulated in time intervals of 10 ms during 10 s. The system starts the count before activating the X-ray apparatus, which is on during a time interval of 100ms. During this period, counts may overflow in consequence high voltage was adjusted to be 40kV, in order to avoid such a problem. For each of these points dose was measured using an ionization chamber. The objectives of this work are to study fluctuations on the X-ray beam and to calibrate the portable probe for measuring radiation doses. Counting rates measured for each 10 ms presented strong variations due to high voltages fluctuations. Both dose and counting rate when correlated with distances between source and detector followed the inverse square law and presented values of R2 near of unit. A calibration curve of the portable system for dose measurements showed also R2 value near of unity. (author)

A Recirculating Linac-Based Facility for Ultrafast X-Ray Science

International Nuclear Information System (INIS)

Corlett, J. N.; Barletta, W. A.; DeSantis, S.; Doolittle, L.; Fawley, W. M.; Green, M.A.; Heimann, P.; Leone, S.; Lidia, S.; Li, D.; Ratti, A.; Robinson, K.; Schoenlein, R.; Staples, J.; Wan, W.; Wells, R.; Wolski, A.; Zholents, A.; Parmigiani, F.; Placidi, M.; Pirkl, W.; Rimmer, R. A.; Wang, S.

2003-01-01

We present an updated design for a proposed source of ultra-fast synchrotron radiation pulses based on a recirculating superconducting linac [1,2], in particular the incorporation of EUV and soft x-ray production. The project has been named LUX--Linac-based Ultrafast X-ray facility. The source produces intense x-ray pulses with duration of 10-100 fs at a 10 kHz repetition rate, with synchronization of 10's fs, optimized for the study of ultra-fast dynamics. The photon range covers the EUV to hard x-ray spectrum by use of seeded harmonic generation in undulators, and a specialized technique for ultra-short pulse photon production in the 1-10 keV range. High brightness rf photocathodes produce electron bunches which are optimized either for coherent emission in free electron lasers, or to provide a large x/y emittance ration and small vertical emittance which allows for manipulation to produce short-pulse hard x-rays. An injector linac accelerates the beam to 120 MeV, and is followed by f our passes through a 600-720 MeV recirculating linac. We outline the major technical components of the proposed facility

The one- and two-coordinate x-ray detectors

International Nuclear Information System (INIS)

Aulchenko, V.M.; Baru, S.E.; Khabakhpashev, A.G.; Savinov, G.A.

1992-01-01

The Institute of Nuclear Physics has designed and fabricated one- and two-coordinate x-ray detectors since 1975. For photon detection multiwire proportional chambers that operate in direct pulse count mode are employed. The characteristics of the detectors allow successful use of them for a wide range of diffractive x-ray structure studies, including studies of dynamics of structure variation (x-ray diffractive movies) and measurements at synchrotron radiation channels

Low cost ESR based X-ray beamline for lithography experimentation

Energy Technology Data Exchange (ETDEWEB)

Kovacs, S.; Doumas, A.; Truncale, M. (Grumman Corp., Bethpage, NY (United States). Space and Electronics Div.)

1992-08-01

Any application of the electron storage ring (ESR) based X-ray lithography technology requires an X-ray radiation transport system to transfer the synchrotron radiation into a spectrum defined by the lithography process requirements. Structure of this transport system (i.e. the beamline) depends on the nature of the application. In this paper a beamline conceptual design will be discussed. The beamline is intended for the developmment of X-ray lithography technology. (orig.).

X-ray holography: X-ray interactions and their effects

International Nuclear Information System (INIS)

London, R.A.; Trebes, J.E.; Rosen, M.D.

1988-01-01

The authors summarize a theoretical study of the interactions of x-rays with a biological sample during the creation of a hologram. The choice of an optimal wavelength for x-ray holography is discussed, based on a description of scattering by objects within an aqueous environment. The problem of the motion resulting from the absorption of x-rays during a short exposure is described. The possibility of using very short exposures in order to capture the image before motion can compromise the resolution is explored. The impact of these calculation on the question of the feasibility of using an x-ray laser for holography of biological structures is discussed. 12 refs., 2 figs

Design of high voltage power supply of miniature X-ray tube based on resonant Royer

International Nuclear Information System (INIS)

Liu Xiyao; Zeng Guoqiang; Tan Chengjun; Luo Qun; Gong Chunhui; Huang Rui

2013-01-01

Background: In recent years, X rays are widely used in various fields. With the rapid development of national economy, the demand of high quality, high reliability, and high stability miniature X-ray tube has grown rapidly. As an important core component of miniature X-ray tube, high voltage power supply has attracted wide attention. Purpose: To match miniature, the high voltage power supply should be small, lightweight, good quality, etc. Based on the basic performance requirements of existing micro-X-ray tube high voltage power supply, this paper designs an output from 0 to -30 kV adjustable miniature X-ray tube voltage DC power supply. Compared to half-bridge and full-bridge switching-mode power supply, its driving circuit is simple. With working on the linear condition, it has no switching noise. Methods: The main circuit makes use of DC power supply to provide the energy. The resonant Royer circuit supplies sine wave which drives to the high frequency transformer's primary winding with resultant sine-like high voltage appearing across the secondary winding. Then, the voltage doubling rectifying circuit would achieve further boost. In the regulator circuit, a feedback control resonant transistor base current is adopted. In order to insulate air, a silicone rubber is used for high pressure part packaging, and the output voltage is measured by the dividing voltage below -5 kV. Results: The stability of circuit is better than 0.2%/6 h and the percent of the output ripple voltage is less than 0.3%. Keeping the output voltage constant, the output current can reach 57 μA by changing the size of load resistor. This high voltage power supply based on resonant Royer can meet the requirement of miniature X-ray tube. Conclusions: The circuit can satisfy low noise, low ripple, low power and high voltage regulator power supply design. However, its efficiency is not high enough because of the linear condition. In the next design, to further reduce power consumption, we

Three-dimensional grain structure of sintered bulk strontium titanate from X-ray diffraction contrast tomography

DEFF Research Database (Denmark)

Syha, M.; Rheinheimer, W.; Bäurer, M.

2012-01-01

The three-dimensional grain boundary network of sintered bulk strontium titanate is reconstructed using X-ray diffraction contrast tomography, a non-destructive technique for determining the grain shape and crystallographic orientation in polycrystals that is ideally suited for detailed studies...

X-Ray Lasers 2016

CERN Document Server

Bulanov, Sergei; Daido, Hiroyuki; Kato, Yoshiaki

2018-01-01

These proceedings comprise a selection of invited and contributed papers presented at the 15th International Conference on X-Ray Lasers (ICXRL 2016), held at the Nara Kasugano International Forum, Japan, from May 22 to 27, 2016. This conference was part of an ongoing series dedicated to recent developments in the science and technology of x-ray lasers and other coherent x-ray sources with additional focus on supporting technologies, instrumentation and applications.   The book showcases recent advances in the generation of intense, coherent x-rays, the development of practical devices and their applications across a wide variety of fields. It also discusses emerging topics such as plasma-based x-ray lasers, 4th generation accelerator-based sources and higher harmonic generations, as well as other x-ray generation schemes.

Deformation-induced crystallographic-preferred orientation of hcp-iron: An experimental study using a deformation-DIA apparatus

Science.gov (United States)

Nishihara, Yu; Ohuchi, Tomohiro; Kawazoe, Takaaki; Seto, Yusuke; Maruyama, Genta; Higo, Yuji; Funakoshi, Ken-ichi; Tange, Yoshinori; Irifune, Tetsuo

2018-05-01

Shear and uniaxial deformation experiments on hexagonal close-packed iron (hcp-Fe) was conducted using a deformation-DIA apparatus at a pressure of 13-17 GPa and a temperature of 723 K to determine its deformation-induced crystallographic-preferred orientation (CPO). Development of the CPO in the deforming sample is determined in-situ based on two-dimensional X-ray diffraction using monochromatic synchrotron X-rays. In the shear deformation geometry, the and axes gradually align to be sub-parallel to the shear plane normal and shear direction, respectively, from the initial random texture. In the uniaxial compression and tensile geometry, the and axes, respectively, gradually align along the direction of the uniaxial deformation axis. These results suggest that basal slip (0001) is the dominant slip system in hcp-Fe under the studied deformation conditions. The P-wave anisotropy for a shear deformed sample was calculated using elastic constants at the inner core condition by recent ab-initio calculations. Strength of the calculated anisotropy was comparable to or higher than axisymmetric anisotropy in Earth's inner core.

A set-up of micro-X-ray fluorescence system based on polycapillary X-ray optics and applications for archaeology

International Nuclear Information System (INIS)

Cheng Lin; Pan Qiuli; Ding Xunliang; Liu Zhiguo

2008-01-01

The paper concerns in the structures, performances and characteristics and applications for archaeology of a new micro-X-ray fluorescence system based on rotating anode X-ray generator and polycapillary X-ray optics. The polycapillary X-ray optics used here can focus the primary X-ray beam down to some tens of micrometers in diameters that allows for non-destructive and local analysis of sub-mm samples with minor/ trace level sensitivity. In order to prove the potentials of this instrument used in archaeology, a piece of Chinese ancient blue and white porcelain produced in Ming Dynasty was analyzed. The results show that intensities of Mn-Kα, Co-Kα are variable in agree with the thick of blue glaze. The correlation analysis indicates the Mn and Co have the best correlations. So, the concentrations or ratios of Mn and Co are crucial to determine the provenance and identify from a fake one of Chinese ancient blue and white porcelain. (authors)

Compact X-ray sources: X-rays from self-reflection

Science.gov (United States)

Mangles, Stuart P. D.

2012-05-01

Laser-based particle acceleration offers a way to reduce the size of hard-X-ray sources. Scientists have now developed a simple scheme that produces a bright flash of hard X-rays by using a single laser pulse both to generate and to scatter an electron beam.

Spectral structure of a polycapillary lens shaped X-ray beam

Science.gov (United States)

Gogolev, A. S.; Filatov, N. A.; Uglov, S. R.; Hampai, D.; Dabagov, S. B.

2018-04-01

Polycapillary X-ray optics is widely used in X-ray analysis techniques to create a small secondary source, for instance, or to deliver X-rays to the point of interest with minimum intensity losses [1]. The main characteristics of the analytical devices on its base are the size and divergence of the focused or translated beam. In this work, we used the photon-counting pixel detector ModuPIX to study the parameters for polycapillary focused X-ray tube radiation as well as the energy and spatial dependences of radiation at the focus. We have characterized the high-speed spectral camera ModuPIX, which is a single Timepix device with a fast parallel readout allowing up to 850 frames per second with 256 × 256 pixels and a 55 μm pitch defined by the frame frequency. By means of the silicon monochromator the energy response function is measured in clustering mode by the energy scan over total X-ray tube spectrum.

Application of small-angle X-ray scattering for differentiation among breast tumors

International Nuclear Information System (INIS)

Changizi, V.; Kheradmand, A. Arab; Oghabian, M.A.

2008-01-01

Small-angle X-ray scattering (SAXS) is an X-ray diffraction-based technique where a narrow collimated beam of X-rays is focused onto a sample and the scattered X-rays recorded by a detector. The pattern of the scattered X-rays carries information on the molecular structure of the material. As breast cancer is the most widespread cancer in women and differentiation among its tumors is important, this project compared the results of coherent X-ray scattering measurements obtained from benign and malignant breast tissues. The energy-dispersive method with a setup including X-ray tube, primary collimator, sample holder, secondary collimator and high-purity germanium (HpGe) detector was used. One hundred thirty-one breast-tissue samples, including normal, fibrocystic changes and carcinoma, were studied at the 6 deg scattering angle. Diffraction profiles (corrected scattered intensity versus momentum transfer) of normal, fibrocystic changes and carcinoma were obtained. These profiles showed a few peak positions for adipose (1.15 ± 0.06 nm -1 ), mixed normal (1.15 ± 0.06 nm -1 and 1.4 ± 0.04 nm -1 ), fibrocystic changes (1.46 ± 0.05 nm -1 and 1.74 ± 0.04 nm -1 ) and carcinoma (1.55 ± 0.04 nm -1 , 1.73 ± 0.06 nm -1 , 1.85 ± 0.05 nm -1 ). We were able to differentiate between normal, fibrocystic changes (benign) and carcinoma (malignant) breast tissues by SAXS. However, we were unable to differentiate between different types of carcinoma. (author)

Application of small-angle X-ray scattering for differentiation among breast tumors

Directory of Open Access Journals (Sweden)

Changizi V

2008-01-01

Full Text Available Small-angle X-ray scattering (SAXS is an X-ray diffraction-based technique where a narrow collimated beam of X-rays is focused onto a sample and the scattered X-rays recorded by a detector. The pattern of the scattered X-rays carries information on the molecular structure of the material. As breast cancer is the most widespread cancer in women and differentiation among its tumors is important, this project compared the results of coherent X-ray scattering measurements obtained from benign and malignant breast tissues. The energy-dispersive method with a setup including X-ray tube, primary collimator, sample holder, secondary collimator and high-purity germanium (HpGe detector was used. One hundred thirty-one breast-tissue samples, including normal, fibrocystic changes and carcinoma, were studied at the 6° scattering angle. Diffraction profiles (corrected scattered intensity versus momentum transfer of normal, fibrocystic changes and carcinoma were obtained. These profiles showed a few peak positions for adipose (1.15 ± 0.06 nm -1 , mixed normal (1.15 ± 0.06 nm -1 and 1.4 ± 0.04 nm -1 , fibrocystic changes (1.46 ± 0.05 nm -1 and 1.74 ± 0.04 nm -1 and carcinoma (1.55 ± 0.04 nm -1 , 1.73 ± 0.06 nm -1 , 1.85 ± 0.05 nm -1 . We were able to differentiate between normal, fibrocystic changes (benign and carcinoma (malignant breast tissues by SAXS. However, we were unable to differentiate between different types of carcinoma.

Producing x-rays

International Nuclear Information System (INIS)

Mallozzi, P.J.; Epstein, H.M.; Jung, R.G.; Applebaum, D.C.; Fairand, B.P.; Gallagher, W.J.

1977-01-01

A method of producing x-rays by directing radiant energy from a laser onto a target is described. Conversion efficiency of at least about 3 percent is obtained by providing the radiant energy in a low-power precursor pulse of approximately uniform effective intensity focused onto the surface of the target for about 1 to 30 nanoseconds so as to generate an expanding unconfined coronal plasma having less than normal solid density throughout and comprising a low-density (underdense) region wherein the plasma frequency is less than the laser radiation frequency and a higher-density (overdense) region wherein the plasma frequency is greater than the laser radiation frequency and, about 1 to 30 nanoseconds after the precursor pulse strikes the target, a higher-power main pulse focused onto the plasma for about 10 -3 to 30 nanoseconds and having such power density and total energy that the radiant energy is absorbed in the underdense region and conducted into the overdense region to heat it and thus to produce x-rays therefrom with the plasma remaining substantially below normal solid density and thus facilitating the substantial emission of x-rays in the form of spectral lines arising from nonequilibrium ionization states

X-ray Imaging and preliminary studies of the X-ray self-emission from an innovative plasma-trap based on the Bernstein waves heating mechanism

Science.gov (United States)

Caliri, C.; Romano, F. P.; Mascali, D.; Gammino, S.; Musumarra, A.; Castro, G.; Celona, L.; Neri, L.; Altana, C.

2013-10-01

Electron Cyclotron Resonance Ion Sources (ECRIS) are based on ECR heated plasmas emitting high fluxes of X-rays. Here we illustrate a pilot study of the X-ray emission from a compact plasma-trap in which an off-resonance microwave-plasma interaction has been attempted, highlighting a possible Bernstein-Waves based heating mechanism. EBWs-heating is obtained via the inner plasma EM-to-ES wave conversion and enables to reach densities much larger than the cut-off ones. At LNS-INFN, an innovative diagnostic technique based on the design of a Pinhole Camera (PHC) coupled to a CCD device for X-ray Imaging of the plasma (XRI) has been developed, in order to integrate X-ray traditional diagnostics (XRS). The complementary use of electrostatic probes measurements and X-ray diagnostics enabled us to gain knowledge about the high energy electrons density and temperature and about the spatial structure of the source. The combination of the experimental data with appropriate modeling of the plasma-source allowed to estimate the X-ray emission intensity in different energy domains (ranging from EUV up to Hard X-rays). The use of ECRIS as X-ray source for multidisciplinary applications, is now a concrete perspective due to the intense fluxes produced by the new plasma heating mechanism.

Elements in normal and cirrhotic human liver. Potassium, iron, copper, zinc and bromine measured by X-ray fluorescence spectrometry

DEFF Research Database (Denmark)

Laursen, J.; Milman, N.; Leth, Peter Mygind

1990-01-01

Various elements (K, Fe, Cu, Zn, Br) were measured by X-ray flourescence spectrometry in cellular and connective tissue fractions of normal and cirrhotic liver samples obtained at autopsy. Normal livers: 32 subjects (16 males, 16 females) median age 69 years. Cirrhotic livers: 14 subjects (13 mal...

X-ray diffraction microtomography using synchrotron radiation

CERN Document Server

Barroso, R C; Jesus, E F O; Oliveira, L F

2001-01-01

The X-ray diffraction computed tomography technique is based on the interference phenomena of the coherent scatter. For low-momentum transfer, it is most probable that the scattering interaction will be coherent. A selective discrimination of a given element in a scanned specimen can be realized by fixing the Bragg angle which produces an interference peak and then, to carry out the computed tomography in the standard mode. The image reconstructed exalts the presence of this element with respect to other ones in a sample. This work reports the feasibility of a non-destructive synchrotron radiation X-ray diffraction imaging technique. This research was performed at the X-ray Diffraction beam line of the National Synchrotron Light Laboratory (LNLS) in Brazil. The coherent scattering properties of different tissue and bone substitute materials were evaluated. Furthermore, diffraction patterns of some polycrystalline solids were studied due to industrial and environmental human exposure to these metals. The obtai...

Vocal fold contact patterns based on normal modes of vibration.

Science.gov (United States)

Smith, Simeon L; Titze, Ingo R

2018-05-17

The fluid-structure interaction and energy transfer from respiratory airflow to self-sustained vocal fold oscillation continues to be a topic of interest in vocal fold research. Vocal fold vibration is driven by pressures on the vocal fold surface, which are determined by the shape of the glottis and the contact between vocal folds. Characterization of three-dimensional glottal shapes and contact patterns can lead to increased understanding of normal and abnormal physiology of the voice, as well as to development of improved vocal fold models, but a large inventory of shapes has not been directly studied previously. This study aimed to take an initial step toward characterizing vocal fold contact patterns systematically. Vocal fold motion and contact was modeled based on normal mode vibration, as it has been shown that vocal fold vibration can be almost entirely described by only the few lowest order vibrational modes. Symmetric and asymmetric combinations of the four lowest normal modes of vibration were superimposed on left and right vocal fold medial surfaces, for each of three prephonatory glottal configurations, according to a surface wave approach. Contact patterns were generated from the interaction of modal shapes at 16 normalized phases during the vibratory cycle. Eight major contact patterns were identified and characterized by the shape of the flow channel, with the following descriptors assigned: convergent, divergent, convergent-divergent, uniform, split, merged, island, and multichannel. Each of the contact patterns and its variation are described, and future work and applications are discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

X-ray detectors based on image sensors

International Nuclear Information System (INIS)

Costa, A.P.R.

1983-01-01

X-ray detectors based on image sensors are described and a comparison is made between the advantages and the disadvantages of such a kind of detectors with the position sensitive detectors. (L.C.) [pt

Characterization of a confocal three-dimensional micro X-ray fluorescence facility based on polycapillary X-ray optics and Kirkpatrick-Baez mirrors

International Nuclear Information System (INIS)

Sun Tianxi; Ding Xunliang; Liu Zhiguo; Zhu Guanghua; Li Yude; Wei Xiangjun; Chen Dongliang; Xu Qing; Liu Quanru; Huang Yuying; Lin Xiaoyan; Sun Hongbo

2008-01-01

A new confocal three-dimensional micro X-ray fluorescence (3D micro-XRF) facility based on polycapillary X-ray optics in the detection channel and Kirkpatrick-Baez (KB) mirrors in the excitation channel is designed. The lateral resolution (l x , l y ) of this confocal three-dimensional micro-X-ray fluorescence facility is 76.3(l x ) and 53.4(l y ) μm respectively, and its depth resolution d z is 77.1 μm at θ = 90 o . A plant sample (twig of B. microphylla) and airborne particles are analyzed

X-ray scattering in X-ray fluorescence spectra with X-ray tube excitation - Modelling, experiment, and Monte-Carlo simulation

International Nuclear Information System (INIS)

Hodoroaba, V.-D.; Radtke, M.; Vincze, L.; Rackwitz, V.; Reuter, D.

2010-01-01

X-ray scattering may contribute significantly to the spectral background of X-ray fluorescence (XRF) spectra. Based on metrological measurements carried out with a scanning electron microscope (SEM) having attached a well characterised X-ray source (polychromatic X-ray tube) and a calibrated energy dispersive X-ray spectrometer (EDS) the accuracy of a physical model for X-ray scattering is systematically evaluated for representative samples. The knowledge of the X-ray spectrometer efficiency, but also of the spectrometer response functions makes it possible to define a physical spectral background of XRF spectra. Background subtraction relying on purely mathematical procedures is state-of-the-art. The results produced by the analytical model are at least as reliable as those obtained by Monte-Carlo simulations, even without considering the very challenging contribution of multiple scattering. Special attention has been paid to Compton broadening. Relevant applications of the implementation of the analytical model presented in this paper are the prediction of the limits of detection for particular cases or the determination of the transmission of X-ray polycapillary lenses.

Analysis of magnetohydrodynamic modes in tokamaks by x-ray techniques

International Nuclear Information System (INIS)

Sauthoff, N.R.

1977-01-01

A brief review of recent studies of fluctuations in x-ray emission from tokamak plasmas of controlled thermonuclear fusion interest is given. The origin of the x-rays, the nature of the oscillations, and measurement and analysis techniques are discussed, with emphasis on the work performed on the ST and PLT tokamaks. Areas for future research, particularly in the region of reconstruction, are stressed

Cation distribution and crystallographic characterization of the spinel oxides MgCr{sub x}Fe{sub 2−x}O{sub 4} by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Zakaria, A.K.M., E-mail: zakaria6403@yahoo.com [Institute of Nuclear Science & Technology, Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Nesa, Faizun [Department of Natural Science, Daffodil International University, Dhaka (Bangladesh); Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh); Saeed Khan, M.A. [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh); Datta, T.K.; Aktar, Sanjida; Liba, Samia Islam; Hossain, Shahzad; Das, A.K.; Kamal, I.; Yunus, S.M. [Institute of Nuclear Science & Technology, Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Eriksson, S.-G. [Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg (Sweden)

2015-06-05

Highlights: • MgCr{sub x}Fe{sub 2−x}O{sub 4} ferrites crystallize at 1300 °C and possess cubic symmetry. • Cation distribution and crystallographic parameters have been determined precisely. • Cell parameter decreases with increasing Cr content in the system. • Ferrimagnetic ordering was found at room temperature for all the samples. - Abstract: The spinel system MgCr{sub x}Fe{sub 2−x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) has been prepared by solid state sintering method in air at 1573 K. X-ray and neutron powder diffraction experiments have been performed on the samples at room temperature for structural characterization. Rietveld refinement of the neutron diffraction data reveals that all the samples of the series possess cubic symmetry corresponding to the space group F d-3m. The distribution of the three cations Mg, Fe and Cr over the two sublattices and other crystallographic parameters has been determined precisely. The results reveal that Cr has been substituted for Fe selectively. Cr ions invariably occupy the octahedral (B) site for all values of x. Mg and Fe ions are distributed over both A and B sites for all x values. With increasing x the occupation of Mg increases in the A site and decreases in the B site for all the samples, while the Fe ions gradually decreases in both the sites for all values of x. The lattice constant decreases with increasing Cr content in the system. The magnetic structure at room temperature was ferrimagnetic for all the samples.

X-ray spectral meter of high voltages for X-ray apparatuses

International Nuclear Information System (INIS)

Zubkov, I.P.; Larchikov, Yu.V.

1993-01-01

Design of the X-ray spectral meter of high voltages (XRSMHV) for medical X-ray apparatuses permitting to conduct the voltage measurements without connection to current circuits. The XRSMHV consists of two main units: the detector unit based on semiconductor detector and the LP4900B multichannel analyzer (Afora, Finland). The XRSMYV was tested using the pilot plant based on RUM-20 X-ray diagnostic apparatus with high-voltage regulator. It was shown that the developed XRSMHV could be certify in the range of high constant voltages form 40 up to 120 kV with the basic relative error limits ±0.15%. The XRSMHV is used at present as the reference means for calibration of high-voltage medical X-ray equipment

A lab-based ambient pressure x-ray photoelectron spectrometer with exchangeable analysis chambers

Energy Technology Data Exchange (ETDEWEB)

Newberg, John T., E-mail: jnewberg@udel.edu; Arble, Chris; Goodwin, Chris; Khalifa, Yehia; Broderick, Alicia [Department of Chemistry & Biochemistry, University of Delaware, Newark, Delaware 19716 (United States); Åhlund, John [Scienta AB, Box 15120, 750 15 Uppsala (Sweden)

2015-08-15

Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a powerful spectroscopy tool that is inherently surface sensitive, elemental, and chemical specific, with the ability to probe sample surfaces under Torr level pressures. Herein, we describe the design of a new lab-based APXPS system with the ability to swap small volume analysis chambers. Ag 3d(5/2) analyses of a silver foil were carried out at room temperature to determine the optimal sample-to-aperture distance, x-ray photoelectron spectroscopy analysis spot size, relative peak intensities, and peak full width at half maximum of three different electrostatic lens modes: acceleration, transmission, and angular. Ag 3d(5/2) peak areas, differential pumping pressures, and pump performance were assessed under varying N{sub 2}(g) analysis chamber pressures up to 20 Torr. The commissioning of this instrument allows for the investigation of molecular level interfacial processes under ambient vapor conditions in energy and environmental research.

The Evolution of Normal Galaxy X-Ray Emission Through Cosmic History: Constraints from the 6 MS Chandra Deep Field-South

Science.gov (United States)

Lehmer, B. D.; Basu-Zych, A. R.; Mineo, S.; Brandt, W. N.; Eurfrasio, R. T.; Fragos, T.; Hornschemeier, A. E.; Lou, B.; Xue, Y. Q.; Bauer, F. E.;

Galaxies in the X-ray Band

Science.gov (United States)

Hornschemeier, Ann

2008-01-01

This talk will provide a brief review of progress on X-ray emission from normal (non-AGN) galaxy populations, including important constraints on the evolution of accreting binary populations over important cosmological timescales. We will also look to the future, anticipating constraints from near-term imaging hard X-ray missions such as NuSTAR, Simbol-X and NeXT and then the longer-term prospects for studying galaxies with the Generation-X mission.

Compact X-ray source based on Compton backscattering

CERN Document Server

Bulyak, E V; Zelinsky, A; Karnaukhov, I; Kononenko, S; Lapshin, V G; Mytsykov, A; Telegin, Yu P; Khodyachikh, A; Shcherbakov, A; Molodkin, V; Nemoshkalenko, V; Shpak, A

2002-01-01

The feasibility study of an intense X-ray source based on the interaction between the electron beam in a compact storage ring and the laser pulse accumulated in an optical resonator is carried out. We propose to reconstruct the 160 MeV electron storage ring N-100, which was shutdown several years ago. A new magnetic lattice will provide a transverse of electron beam size of approx 35 mu m at the point of electron beam-laser beam interaction. The proposed facility is to generate X-ray beams of intensity approx 2.6x10 sup 1 sup 4 s sup - sup 1 and spectral brightness approx 10 sup 1 sup 2 phot/0.1%bw/s/mm sup 2 /mrad sup 2 in the energy range from 10 keV up to 0.5 MeV. These X-ray beam parameters meet the requirements for most of technological and scientific applications. Besides, we plan to use the new facility for studying the laser cooling effect.

Compact X-ray source based on Compton backscattering

Energy Technology Data Exchange (ETDEWEB)

Bulyak, E.; Gladkikh, P.; Zelinsky, A. E-mail: zelinsky@kipt.kharkov.ua; Karnaukhov, I.; Kononenko, S.; Lapshin, V.; Mytsykov, A.; Telegin, Yu.; Khodyachikh, A.; Shcherbakov, A.; Molodkin, V.; Nemoshkalenko, V.; Shpak, A

2002-07-21

The feasibility study of an intense X-ray source based on the interaction between the electron beam in a compact storage ring and the laser pulse accumulated in an optical resonator is carried out. We propose to reconstruct the 160 MeV electron storage ring N-100, which was shutdown several years ago. A new magnetic lattice will provide a transverse of electron beam size of {approx}35 {mu}m at the point of electron beam-laser beam interaction. The proposed facility is to generate X-ray beams of intensity {approx}2.6x10{sup 14} s{sup -1} and spectral brightness {approx}10{sup 12} phot/0.1%bw/s/mm{sup 2}/mrad{sup 2} in the energy range from 10 keV up to 0.5 MeV. These X-ray beam parameters meet the requirements for most of technological and scientific applications. Besides, we plan to use the new facility for studying the laser cooling effect.

Simulation of transmitted X-rays in a polycapillary X-ray lens

Energy Technology Data Exchange (ETDEWEB)

Peng, Shiqi [The Key Laboratory of Beam Technology and Material Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Liu, Zhiguo, E-mail: liuzhiguo512@126.com [The Key Laboratory of Beam Technology and Material Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Sun, Tianxi; Wang, Kai; Yi, Longtao; Yang, Kui; Chen, Man; Wang, Jinbang [The Key Laboratory of Beam Technology and Material Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

2015-09-21

The geometrical description of capillary systems adjusted for the controlled guiding of X-rays and the basic theory of the transmission of X-rays are presented. A method of numerical calculation, based on Ray-Tracing theory, is developed to simulate the transmission efficiency of an X-ray parallel lens and the shape and size of the light spot gain from it. The simulation results for two half-lenses are in good agreement with the experimental results.

X-ray cluster Abell 744

International Nuclear Information System (INIS)

Kurtz, M.J.; Huchra, J.P.; Beers, T.C.; Geller, M.J.; Gioia, I.M.

1985-01-01

X-ray and optical observations of the cluster of galaxies Abell 744 are presented. The X-ray flux (assuming H(0) = 100 km/s per Mpc) is about 9 x 10 to the 42nd erg/s. The X-ray source is extended, but shows no other structure. Photographic photometry (in Kron-Cousins R), calibrated by deep CCD frames, is presented for all galaxies brighter than 19th magnitude within 0.75 Mpc of the cluster center. The luminosity function is normal, and the isopleths show little evidence of substructure near the cluster center. The cluster has a dominant central galaxy, which is classified as a normal brightest-cluster elliptical on the basis of its luminosity profile. New redshifts were obtained for 26 galaxies in the vicinity of the cluster center; 20 appear to be cluster members. The spatial distribution of redshifts is peculiar; the dispersion within the 150 kpc core radius is much greater than outside. Abell 744 is similar to the nearby cluster Abell 1060. 31 references

Koehler/Zimmer: The X-ray findings of the skeleton marking off the onset of pathological changes against normal conditions. 13. rev. ed.

International Nuclear Information System (INIS)

Schmidt, H.; Freyschmidt, J.; Holthusen, W.

1989-01-01

It is extremely difficult to define the border line, or border area, between normal and pathological conditions. This applies in particular to diagnostic radiology of the skeleton. Although the X-ray picture of a certain skeletal area in principle yields more objective information than the anamnestic data given by the patient, or the clinical findings, this more objective information in borderline cases will develop its full usefulness only if X-ray or clinical findings are interpreted synoptically, sometimes with recourse to other radiological techniques (such as scintiscanning, CT, or NMR imaging). This also is the suitable approach to evaluating and interpreting measured anatomic data as for instance shape or size. Transitions from normal conditions to pathological processes cannot be seen in the image, they will have to be defined in every case by negative exclusion, and this is why the book in hand is neither an atlas of normal X-ray anatomy, nor a collection of differential diagnostic X-ray findings of the skeleton. Having regard to practical requirements and respecting the excellent picture material of the preceding issue, the authors in some cases decided to assign borderline findings rather to the pathological types. (orig./MG) With 2816 figs., 16 tabs [de

Cephalometric landmark detection in dental x-ray images using convolutional neural networks

Science.gov (United States)

Lee, Hansang; Park, Minseok; Kim, Junmo

2017-03-01

In dental X-ray images, an accurate detection of cephalometric landmarks plays an important role in clinical diagnosis, treatment and surgical decisions for dental problems. In this work, we propose an end-to-end deep learning system for cephalometric landmark detection in dental X-ray images, using convolutional neural networks (CNN). For detecting 19 cephalometric landmarks in dental X-ray images, we develop a detection system using CNN-based coordinate-wise regression systems. By viewing x- and y-coordinates of all landmarks as 38 independent variables, multiple CNN-based regression systems are constructed to predict the coordinate variables from input X-ray images. First, each coordinate variable is normalized by the length of either height or width of an image. For each normalized coordinate variable, a CNN-based regression system is trained on training images and corresponding coordinate variable, which is a variable to be regressed. We train 38 regression systems with the same CNN structure on coordinate variables, respectively. Finally, we compute 38 coordinate variables with these trained systems from unseen images and extract 19 landmarks by pairing the regressed coordinates. In experiments, the public database from the Grand Challenges in Dental X-ray Image Analysis in ISBI 2015 was used and the proposed system showed promising performance by successfully locating the cephalometric landmarks within considerable margins from the ground truths.

Evaluation of stress gradient by x-ray stress measurement based on change in angle phi

International Nuclear Information System (INIS)

Sasaki, Toshihiko; Kuramoto, Makoto; Yoshioka, Yasuo.

1985-01-01

A new principle of X-ray stress evaluation for a sample with steep stress gradient has been prosed. The feature of this method is that the stress is determined by using so-called phi-method based on the change of phi-angle and thus has no effect on the penetration depth of X-rays. The procedure is as follows; firstly, an average stress within the penetration depth of X-rays is determined by changing only phi-angle under a fixed psi-angle, and then a distribution of the average stress vs. the penetration depth of X-rays is detected by repeating the similar procedure at different psi-angles. The following conclusions were found out as the result of residual stress measurements on a carbon steel of type S 55 C polished by emery paper. This method is practical enough to use for a plane stress problem. And the assumption of a linear stress gradient adopted in the authors' previous investigations is valid. In case of a triaxial stress analysis, this method is effective for the solution of three shearing stresses. However, three normal stresses can not be solved perfectly except particular psi-angles. (author)

An X-ray scanner prototype based on a novel hybrid gaseous detector

CERN Document Server

Iacobaeus, C; Lund-Jensen, B; Peskov, Vladimir

2007-01-01

We have developed a prototype of a new type of hybrid X-ray detector. It contains a thin wall (few μm) edge- illuminated lead glass capillary plate (acting as a converter of X-rays photons to primary electrons) combined with a microgap parallel-plate avalanche chamber operating in various gas mixtures at 1 atm. The operation of these converters was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident angles varying from 0° to 90°. The detection efficiency, depending on the geometry, photon's energy, incident angle and the mode of operation, was between a few and 40%. The position resolution achieved was 50 μm in digital form and was practically independent of the photon's energy or gas mixture. The developed detector may open new possibilities for medical imaging, for example in mammography, portal imaging, radiography (including security devices), crystallography and many other applications.

Development of an X-ray fluorescence holographic measurement system for protein crystals

International Nuclear Information System (INIS)

Sato-Tomita, Ayana; Shibayama, Naoya; Okabe, Takahiro; Happo, Naohisa; Kimura, Koji; Matsushita, Tomohiro; Park, Sam-Yong; Sasaki, Yuji C.; Hayashi, Kouichi

2016-01-01

Experimental procedure and setup for obtaining X-ray fluorescence hologram of crystalline metalloprotein samples are described. Human hemoglobin, an α_2β_2 tetrameric metalloprotein containing the Fe(II) heme active-site in each chain, was chosen for this study because of its wealth of crystallographic data. A cold gas flow system was introduced to reduce X-ray radiation damage of protein crystals that are usually fragile and susceptible to damage. A χ-stage was installed to rotate the sample while avoiding intersection between the X-ray beam and the sample loop or holder, which is needed for supporting fragile protein crystals. Huge hemoglobin crystals (with a maximum size of 8 × 6 × 3 mm"3) were prepared and used to keep the footprint of the incident X-ray beam smaller than the sample size during the entire course of the measurement with the incident angle of 0°-70°. Under these experimental and data acquisition conditions, we achieved the first observation of the X-ray fluorescence hologram pattern from the protein crystals with minimal radiation damage, opening up a new and potential method for investigating the stereochemistry of the metal active-sites in biomacromolecules.

Potentiation by caffeine of x-ray damage to cultured human skin fibroblasts from normal subjects and ataxia-telangiectasia patients

International Nuclear Information System (INIS)

Furcinitti, P.S.

1983-01-01

Caffeine was found to potentiate x-ray-induced killing of human diploid fibroblasts from a normal subject and an ataxia-telangiectasia (AT) patient when it was present at 2 mM concentration for 30 to 66 h postirradiation. The dose-modifying factor for caffeine-treated normal cells had an average value of 1.26 +- 0.13 which did not vary significantly with treatment time or x-ray dose. The dose-modifying factor for caffeine-treated AT cells was 1.12 +- 0.12 at 30 h, rose to 1.66 +- 0.17 at 41 h, and decreased to 1.31 +- 0.13 at 66 h. Thus no clear difference was observed between these two cell strains' susceptibility to postirradiation caffeine treatment

Analyser-based x-ray imaging for biomedical research

International Nuclear Information System (INIS)

Suortti, Pekka; Keyriläinen, Jani; Thomlinson, William

2013-01-01

Analyser-based imaging (ABI) is one of the several phase-contrast x-ray imaging techniques being pursued at synchrotron radiation facilities. With advancements in compact source technology, there is a possibility that ABI will become a clinical imaging modality. This paper presents the history of ABI as it has developed from its laboratory source to synchrotron imaging. The fundamental physics of phase-contrast imaging is presented both in a general sense and specifically for ABI. The technology is dependent on the use of perfect crystal monochromator optics. The theory of the x-ray optics is developed and presented in a way that will allow optimization of the imaging for specific biomedical systems. The advancement of analytical algorithms to produce separate images of the sample absorption, refraction angle map and small-angle x-ray scattering is detailed. Several detailed applications to biomedical imaging are presented to illustrate the broad range of systems and body sites studied preclinically to date: breast, cartilage and bone, soft tissue and organs. Ultimately, the application of ABI in clinical imaging will depend partly on the availability of compact sources with sufficient x-ray intensity comparable with that of the current synchrotron environment. (paper)

Grating-based X-ray phase contrast for biomedical imaging applications

International Nuclear Information System (INIS)

Pfeiffer, Franz; Willner, Marian; Chabior, Michael; Herzen, Julia; Helmholtz-Zentrum Geesthacht, Geesthacht; Auweter, Sigrid; Reiser, Maximilian; Bamberg, Fabian

2013-01-01

In this review article we describe the development of grating-based X-ray phase-contrast imaging, with particular emphasis on potential biomedical applications of the technology. We review the basics of image formation in grating-based phase-contrast and dark-field radiography and present some exemplary multimodal radiography results obtained with laboratory X-ray sources. Furthermore, we discuss the theoretical concepts to extend grating-based multimodal radiography to quantitative transmission, phase-contrast, and dark-field scattering computed tomography. (orig.)

Production and X-ray crystallographic analysis of fully deuterated human carbonic anhydrase II

Energy Technology Data Exchange (ETDEWEB)

Budayova-Spano, Monika [European Molecular Biology Laboratory Grenoble Outstation, 6 Rue Jules Horowitz, 38042 Grenoble (France); Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble (France); Fisher, S. Zoë [Department of Biochemistry and Molecular Biology, PO Box 100245, University of Florida, Gainesville, FL 32610 (United States); Dauvergne, Marie-Thérèse [European Molecular Biology Laboratory Grenoble Outstation, 6 Rue Jules Horowitz, 38042 Grenoble (France); Agbandje-McKenna, Mavis [Department of Biochemistry and Molecular Biology, PO Box 100245, University of Florida, Gainesville, FL 32610 (United States); Silverman, David N. [Department of Pharmacology and Therapeutics, PO Box 100267, University of Florida, Gainesville, FL 32610 (United States); Myles, Dean A. A. [European Molecular Biology Laboratory Grenoble Outstation, 6 Rue Jules Horowitz, 38042 Grenoble (France); Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831 (United States); McKenna, Robert, E-mail: rmckenna@ufl.edu [Department of Biochemistry and Molecular Biology, PO Box 100245, University of Florida, Gainesville, FL 32610 (United States); European Molecular Biology Laboratory Grenoble Outstation, 6 Rue Jules Horowitz, 38042 Grenoble (France)

2006-01-01

This article reports the production, crystallization and X-ray structure determination of perdeuterated human carbonic anhydrase (HCA II). The refined structure is shown to be highly isomorphous with hydrogenated HCA II, especially with regard to the active site architecture and solvent network. Human carbonic anhydrase II (HCA II) is a zinc metalloenzyme that catalyzes the reversible hydration and dehydration of carbon dioxide and bicarbonate, respectively. The rate-limiting step in catalysis is the intramolecular transfer of a proton between the zinc-bound solvent (H{sub 2}O/OH{sup −}) and the proton-shuttling residue His64. This distance (∼7.5 Å) is spanned by a well defined active-site solvent network stabilized by amino-acid side chains (Tyr7, Asn62, Asn67, Thr199 and Thr200). Despite the availability of high-resolution (∼1.0 Å) X-ray crystal structures of HCA II, there is currently no definitive information available on the positions and orientations of the H atoms of the solvent network or active-site amino acids and their ionization states. In preparation for neutron diffraction studies to elucidate this hydrogen-bonding network, perdeuterated HCA II has been expressed, purified, crystallized and its X-ray structure determined to 1.5 Å resolution. The refined structure is highly isomorphous with hydrogenated HCA II, especially with regard to the active-site architecture and solvent network. This work demonstrates the suitability of these crystals for neutron macromolecular crystallography.

CASTOR: Normal-mode analysis of resistive MHD plasmas

NARCIS (Netherlands)

Kerner, W.; Goedbloed, J. P.; Huysmans, G. T. A.; Poedts, S.; Schwarz, E.

1998-01-01

The CASTOR (complex Alfven spectrum of toroidal plasmas) code computes the entire spectrum of normal-modes in resistive MHD for general tokamak configurations. The applied Galerkin method, in conjunction with a Fourier finite-element discretisation, leads to a large scale eigenvalue problem A (x)

Wide field x-ray telescopes: Detecting x-ray transients/afterglows related to GRBs

International Nuclear Information System (INIS)

Hudec, Rene; Pina, Ladislav; Inneman, Adolf; Gorenstein, Paul

1998-01-01

The recent discovery of X-ray afterglows of GRBs opens the possibility of analyses of GRBs by their X-ray detections. However, imaging X-ray telescopes in current use mostly have limited fields of view. Alternative X-ray optics geometries achieving very large fields of view have been theoretically suggested in the 70's but not constructed and used so far. We review the geometries and basic properties of the wide-field X-ray optical systems based on one- and two-dimensional lobster-eye geometry and suggest technologies for their development and construction. First results of the development of double replicated X-ray reflecting flats for use in one-dimensional X-ray optics of lobster-eye type are presented and discussed. The optimum strategy for locating GRBs upon their X-ray counterparts is also presented and discussed

Multiple mode x-ray ptychography using a lens and a fixed diffuser optic

International Nuclear Information System (INIS)

Li, Peng; Batey, Darren J; Rodenburg, John M; Edo, Tega B; Parsons, Aaron D; Rau, Christoph

2016-01-01

We employ a novel combination of a Fresnel lens and a diffuser for x-ray ptychography. The setup uses increased flux by enlarging the width of the coherence-defining slits upstream of the experimental station. In the reconstruction algorithm, modal decomposition is used to account for the resulting partial coherence in the beam. We show that if the object has sparse feactures and large areas of flat contrast, the diffuser facilitates a better reconstruction and the extra diversity in the data also allows cleaner separation of the constituent modes in the illumination. The setup also allows a quick, real-time measure of the beam coherence. (paper)

Expression, crystallization and preliminary X-ray crystallographic analysis of Xoo0352, d-alanine-d-alanine ligase A, from Xanthomonas oryzae pv. oryzae

International Nuclear Information System (INIS)

Doan, Thanh Thi Ngoc; Kim, Jin-Kwang; Kim, Hyesoon; Ahn, Yeh-Jin; Kim, Jeong-Gu; Lee, Byoung-Moo; Kang, Lin-Woo

2008-01-01

Xoo0352, which encodes d-alanine-d-alanine ligase A (DdlA), from X. oryzae pv. oryzae was cloned, purified and crystallized. Preliminary X-ray crystallographic analysis of DdlA crystals was performed. Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight (BB), which is one of the most devastating diseases of rice in most rice-growing countries. d-Alanine-d-alanine ligase A (DdlA), coded by the Xoo0352 gene, was expressed, purified and crystallized. DdlA is an enzyme that is involved in d-alanine metabolism and the biosynthesis of an essential bacterial peptidoglycan precursor, in which it catalyzes the formation of d-alanyl-d-alanine from two d-alanines, and is thus an attractive antibacterial drug target against Xoo. The DdlA crystals diffracted to 2.3 Å resolution and belonged to the primitive tetragonal space group P4 3 2 1 2, with unit-cell parameters a = b = 83.0, c = 97.6 Å. There is one molecule in the asymmetric unit, with a corresponding V M of 1.88 Å 3 Da −1 and a solvent content of 34.6%. The initial structure was determined by molecular replacement using d-alanine-d-alanine ligase from Staphylococcus aureus as a template model

An Alpha Proton X-Ray Spectrometer for Mars-96 and Mars Pathfinder

Science.gov (United States)

Rieder, R.; Wanke, H.; Economou, T.

1996-09-01

Mars Pathfinder and the Russian Mars-96 will carry an Alpha Proton X-Ray Spectrometer (APXS) for the determination of the chemical composition of Martian rocks and soil. The instrument will measure the concentration of all major and many minor elements, including C,N and O, at levels above typically 1%. The method employed consist of bombarding a sample of 50 mm diameter with alpha particles from a radioactive source (50 mCi of Cm-244) and measuring: (i) backscattered alpha particles (alpha mode) (ii) protons from (a,p) reactions with some light elements (proton mode) (iii) characteristic X-rays emitted from the sample (X-ray mode). The APXS has a long standing space heritage, going back to Surveyor V,VI and VII (1967/68) and the Soviet Phobos (1988) missions. The present design is the result of an endeavour to reduce mass and power consumption to 600g/ 300mW. It consist of a sensor head containing the alpha sources, a telescope of a silicon detectors for the detection of the alpha particles and protons and a separate X-ray detector with its preamplifier, and an electronics box (80x70x60 mm) containing a microcontroller based multichannel spectrometer. The paper will describe the APXS flight hardware and present results obtained with the flight instrument that will show the instrument capabili- ties and the expected results to be obtained during surface operations on Mars.

Development and characterization of a laser-based hard x-ray source

International Nuclear Information System (INIS)

Tillman, C.

1996-11-01

A laser-produced plasma was generated by focusing 100 fs laser pulses, with an energy of 150 mJ, onto metal targets. The laser intensity was expected to reach 10 17 W/cm -2 . Radiation was emitted from the created plasma, with photon energies up to the MeV region. The laser-based X-ray source was optimized, with the purpose of making it a realistic source of hard X-rays (>10 keV). Dedicated equipment was developed for efficient generation and utilization of the hard X-rays. The X-ray source was characterized with respect to its spatial extent and the X-ray yield. Measurements were made of the spectral distribution, by the use of single-photon-counting detectors in different geometries, crystal spectrometers and dose measurements in combination with absorption filters. Ablation of the target material in the laser produced plasma was investigated. Imaging applications have been demonstrated, including ultrafast (picosecond) X-ray imaging, magnification imaging of up to x80, differential imaging in the spectral domain, and imaging of various biological and technical objects. The biological response of ultra-intense X-ray pulses was assessed in cell-culture exposures. The results indicate that the biological response from ultra-intense X-ray exposures is similar to the response with conventional X-ray tubes. 82 refs., 14 figs

Development and characterization of a laser-based hard x-ray source

Energy Technology Data Exchange (ETDEWEB)

Tillman, C.

1996-11-01

A laser-produced plasma was generated by focusing 100 fs laser pulses, with an energy of 150 mJ, onto metal targets. The laser intensity was expected to reach 10{sup 17} W/cm{sup -2}. Radiation was emitted from the created plasma, with photon energies up to the MeV region. The laser-based X-ray source was optimized, with the purpose of making it a realistic source of hard X-rays (>10 keV). Dedicated equipment was developed for efficient generation and utilization of the hard X-rays. The X-ray source was characterized with respect to its spatial extent and the X-ray yield. Measurements were made of the spectral distribution, by the use of single-photon-counting detectors in different geometries, crystal spectrometers and dose measurements in combination with absorption filters. Ablation of the target material in the laser produced plasma was investigated. Imaging applications have been demonstrated, including ultrafast (picosecond) X-ray imaging, magnification imaging of up to x80, differential imaging in the spectral domain, and imaging of various biological and technical objects. The biological response of ultra-intense X-ray pulses was assessed in cell-culture exposures. The results indicate that the biological response from ultra-intense X-ray exposures is similar to the response with conventional X-ray tubes. 82 refs., 14 figs.

Simulation of high-resolution X-ray microscopic images for improved alignment

International Nuclear Information System (INIS)

Song Xiangxia; Zhang Xiaobo; Liu Gang; Cheng Xianchao; Li Wenjie; Guan Yong; Liu Ying; Xiong Ying; Tian Yangchao

2011-01-01

The introduction of precision optical elements to X-ray microscopes necessitates fine realignment to achieve optimal high-resolution imaging. In this paper, we demonstrate a numerical method for simulating image formation that facilitates alignment of the source, condenser, objective lens, and CCD camera. This algorithm, based on ray-tracing and Rayleigh-Sommerfeld diffraction theory, is applied to simulate the X-ray microscope beamline U7A of National Synchrotron Radiation Laboratory (NSRL). The simulations and imaging experiments show that the algorithm is useful for guiding experimental adjustments. Our alignment simulation method is an essential tool for the transmission X-ray microscope (TXM) with optical elements and may also be useful for the alignment of optical components in other modes of microscopy.

CONTINUING THE DEVELOPMENT OF A 100 FEMTOSECOND X-RAY DETECTOR

International Nuclear Information System (INIS)

Zenghu Chang

2005-01-01

The detector is an x-ray streak camera running in accumulation mode for time resolved x-ray studies at the existing third generation synchrotron facilities and will also be used for the development and applications of the fourth generation x-ray sources. We have made significant progress on both the detector development and its applications at Synchrotron facilities

New X-Ray Technique to Characterize Nanoscale Precipitates in Aged Aluminum Alloys

Science.gov (United States)

Sitdikov, V. D.; Murashkin, M. Yu.; Valiev, R. Z.

2017-10-01

This paper puts forward a new technique for measurement of x-ray patterns, which enables to solve the problem of identification and determination of precipitates (nanoscale phases) in metallic alloys of the matrix type. The minimum detection limit of precipitates in the matrix of the base material provided by this technique constitutes as little as 1%. The identification of precipitates in x-ray patterns and their analysis are implemented through a transmission mode with a larger radiation area, longer holding time and higher diffractometer resolution as compared to the conventional reflection mode. The presented technique has been successfully employed to identify and quantitatively describe precipitates formed in the Al alloy of the Al-Mg-Si system as a result of artificial aging. For the first time, the x-ray phase analysis has been used to identify and measure precipitates formed during the alloy artificial aging.

X-ray microbeams based on Kumakhov polycapillary optics and its

Indian Academy of Sciences (India)

Kumakhov polycapillary optics is based on the effective passage of X-ray radiation through bundles of monocapillaries of various configurations. The passage of radiation takes place because of the total external reflection of X-rays from the inner capillary walls. In this work,the basic characteristics of intense quasi-parallel ...

Modal study of refractive effects on x-ray laser coherence

International Nuclear Information System (INIS)

Amendt, P.; London, R.A.; Strauss, M.

1991-01-01

The role of smoothly varying transverse gain and refraction profiles on x-ray laser intensity and coherence is analyzed by modally expanding the electric field within the paraxial approximation. Comparison with a square transverse profile reveals that smooth-edged profiles lead to: (1) a greatly reduced number of guided modes, (2) the continued cancellation of local intensity from a loosely guided mode by resonant free modes, (3) and the absence of extraneous (or anomalous) free mode resonances. These generic spectral properties should enable a considerable simplification in analyzing and optimizing the coherence properties of laboratory soft x-ray lasers. 6 refs., 3 figs

X-ray states of redback millisecond pulsars

Energy Technology Data Exchange (ETDEWEB)

Linares, M. [Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain)

2014-11-01

Compact binary millisecond pulsars with main-sequence donors, often referred to as 'redbacks', constitute the long-sought link between low-mass X-ray binaries and millisecond radio pulsars and offer a unique probe of the interaction between pulsar winds and accretion flows. We present a systematic study of eight nearby redbacks, using more than 100 observations obtained with Swift's X-ray Telescope. We distinguish between three main states: pulsar, disk, and outburst states. We find X-ray mode switching in the disk state of PSR J1023+0038 and XSS J12270-4859, similar to what was found in the other redback that showed evidence for accretion: rapid, recurrent changes in X-ray luminosity (0.5-10 keV, L {sub X}), between (6-9) × 10{sup 32} erg s{sup –1} (disk-passive state) and (3-5) × 10{sup 33} erg s{sup –1} (disk-active state). This strongly suggests that mode switching—which has not been observed in quiescent low-mass X-ray binaries—is universal among redback millisecond pulsars in the disk state. We briefly explore the implications for accretion disk truncation and find that the inferred magnetospheric radius in the disk state of PSR J1023+0038 and XSS J12270-4859 lies outside the light cylinder. Finally, we note that all three redbacks that have developed accretion disks have relatively high L {sub X} in the pulsar state (>10{sup 32} erg s{sup –1}).

The forgotten view: Chest X-ray - Lateral view

Directory of Open Access Journals (Sweden)

Abraham M. Ittyachen

2017-01-01

Full Text Available With CT (computed tomography chest gaining more importance as a diagnostic tool, chest X-ray especially the lateral view is taken less commonly nowadays. Besides CT chest is also proven to be superior to chest X-ray in patients with major blunt trauma. We are presenting a 68-year old male who was partially treated from outside for a left sided pneumonia. He came to our hospital because of persisting chest pain. Chest X-ray, frontal view (postero-anterior was almost normal except for a mild opacity in the left lower zone. CT scan of the chest revealed a fluid collection posteriorly enclosed within enhancing pleura. Chest X-ray, left lateral view showed a corresponding posterior pleural based opacity. We are presenting this case to highlight the importance of the lateral view of the chest X-ray. In selected cases there is still a role for the lateral view. With the three dimensional visualization provided by the CT, the lateral view of the chest may be easier to understand. Consequent to the initial diagnosis by CT further follow up can be done with the chest X-ray. In a limited way this mitigates unnecessary expenditure and more importantly prevents the patient from exposure to harmful radiation in the form of repeated CT.

A hard X-ray scanning microprobe for fluorescence imaging and microdiffraction at the Advanced Photon Source

International Nuclear Information System (INIS)

Cai, L.; Lai, B.; Yun, W.; Ilinski, P.; Legnini, D.; Maser, J.; Rodrigues, W.

1999-01-01

A hard x-ray scanning microprobe based on zone plate optics and undulator radiation, in the energy region from 6 to 20 keV, has reached a focal spot size (FWHM) of 0.15 microm (v) x 0.6 microm (h), and a photon flux of 4 x 10 9 photons/sec/0.01%BW. Using a slit 44 meters upstream to create a virtual source, a circular beam spot of 0.15 microm in diameter can be obtained with a photon flux of one order of magnitude less. During fluorescence mapping of trace elements in a single human ovarian cell, the microprobe exhibited an imaging sensitivity for Pt (L a line) of 80 attograms/microm 2 for a count rate of 10 counts per second. The x-ray microprobe has been used to map crystallographic strain and multiquantum well thickness in micro-optoelectronic devices produced with the selective area growth technique

Pixel readout ASIC for an APD based 2D X-ray hybrid pixel detector with sub-nanosecond resolution

Energy Technology Data Exchange (ETDEWEB)

Thil, Ch., E-mail: christophe.thil@ziti.uni-heidelberg.d [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Baron, A.Q.R. [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Fajardo, P. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France); Fischer, P. [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Graafsma, H. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Rueffer, R. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France)

2011-02-01

The fast response and the short recovery time of avalanche photodiodes (APDs) in linear mode make those devices ideal for direct X-ray detection in applications requiring high time resolution or counting rate. In order to provide position sensitivity, the XNAP project aims at creating a hybrid pixel detector with nanosecond time resolution based on a monolithic APD sensor array with 32 x32 pixels covering about 1 cm{sup 2} active area. The readout is implemented in a pixelated front-end ASIC suited for the readout of such arrays, matched to pixels of 280{mu}mx280{mu}m size. Every single channel features a fast transimpedance amplifier, a discriminator with locally adjustable threshold and two counters with high dynamic range and counting speed able to accumulate X-ray hits with no readout dead time. Additionally, the detector can be operated in list mode by time-stamping every single event with sub-nanosecond resolution. In a first phase of the project, a 4x4 pixel test module is built to validate the conceptual design of the detector. The XNAP project is briefly presented and the performance of the readout ASIC is discussed.

Pixel readout ASIC for an APD based 2D X-ray hybrid pixel detector with sub-nanosecond resolution

International Nuclear Information System (INIS)

Thil, Ch.; Baron, A.Q.R.; Fajardo, P.; Fischer, P.; Graafsma, H.; Rueffer, R.

2011-01-01

The fast response and the short recovery time of avalanche photodiodes (APDs) in linear mode make those devices ideal for direct X-ray detection in applications requiring high time resolution or counting rate. In order to provide position sensitivity, the XNAP project aims at creating a hybrid pixel detector with nanosecond time resolution based on a monolithic APD sensor array with 32 x32 pixels covering about 1 cm 2 active area. The readout is implemented in a pixelated front-end ASIC suited for the readout of such arrays, matched to pixels of 280μmx280μm size. Every single channel features a fast transimpedance amplifier, a discriminator with locally adjustable threshold and two counters with high dynamic range and counting speed able to accumulate X-ray hits with no readout dead time. Additionally, the detector can be operated in list mode by time-stamping every single event with sub-nanosecond resolution. In a first phase of the project, a 4x4 pixel test module is built to validate the conceptual design of the detector. The XNAP project is briefly presented and the performance of the readout ASIC is discussed.

A development of laser-plasma-based soft x-ray microscope system

International Nuclear Information System (INIS)

Nam, Ki Yong; Kim, Kyong Woo; Kim, Kyu Gyeom; Kwon, Young Man; Yoon, Kwon Ha

2003-01-01

Soft x-ray nano-imaging microscopy system for biomedical application with a high resolution about 50 nm has been designed and described, and its integrated techniques also have been studied. The system is mainly composed of soft x-ray generation system, nano-scaled control system, x-ray optical device like a condenser or object mirror, a CCD camera coupled with multichannel plate (MCP) and vacuum system. In the system, soft x-ray is generated from the laser-based plasma by focusing Nd:YAG laser beam on tantalum (Ta) target. In an x-ray optical system, a wolter mirror has been considering condensing the x-ray beam on a biological specimen and zone plate was adapted as an object mirror. A Si 3 N 4 was used as specimen holder for keeping a biological sample alive in atmosphere conditions. A back-illuminated-CCD camera coupled with multichannel plate was determined to set up.

A development of laser-plasma-based soft x-ray microscope system

Energy Technology Data Exchange (ETDEWEB)

Nam, Ki Yong; Kim, Kyong Woo; Kim, Kyu Gyeom; Kwon, Young Man; Yoon, Kwon Ha [X-ray Microscopy Research Center, Wonkwang University, Iksan (Korea, Republic of)

2003-07-01

Soft x-ray nano-imaging microscopy system for biomedical application with a high resolution about 50 nm has been designed and described, and its integrated techniques also have been studied. The system is mainly composed of soft x-ray generation system, nano-scaled control system, x-ray optical device like a condenser or object mirror, a CCD camera coupled with multichannel plate (MCP) and vacuum system. In the system, soft x-ray is generated from the laser-based plasma by focusing Nd:YAG laser beam on tantalum (Ta) target. In an x-ray optical system, a wolter mirror has been considering condensing the x-ray beam on a biological specimen and zone plate was adapted as an object mirror. A Si{sub 3}N{sub 4} was used as specimen holder for keeping a biological sample alive in atmosphere conditions. A back-illuminated-CCD camera coupled with multichannel plate was determined to set up.

Crystallization and preliminary X-ray crystallographic analysis of dioscorin from Dioscorea japonica.

Science.gov (United States)

Xue, You-Lin; Miyakawa, Takuya; Sawano, Yoriko; Tanokura, Masaru

2012-02-01

Dioscorin, the major tuber storage protein in yam, has been reported to possess carbonic anhydrase, trypsin inhibitor, angiotensin-converting enzyme (ACE) inhibitor, free-radical scavenger, dehydroascorbate reductase and monodehydroascorbate reductase activities. Recent research has also found that dioscorin can enhance immune modulation via the toll-like receptor 4 (TLR-4) signal transduction pathway in RAW 264.7 cells, murine bone-marrow cells and human monocytes ex vivo. Resolving the structure of dioscorin would help in better understanding its activities and would provide clues to understanding the mechanism of its multiple functions. The full-length protein (residues 1-246) with an additional His(6) tag at the N-terminus was expressed in Escherichia coli Rosetta (DE3) cells. After His-tag cleavage and purification, the protein was crystallized by the sitting-drop vapour-diffusion method at 278 K. An X-ray diffraction data set was collected to a resolution of 2.11 Å using a synchrotron X-ray source. The crystal belonged to space group C222(1), with unit-cell parameters a = 83.5, b = 156.8, c = 83.6 Å, and was estimated to contain two protein molecules per asymmetric unit.

Flexible X-ray detector based on sliced lead iodide crystal

Energy Technology Data Exchange (ETDEWEB)

Sun, Hui; Gao, Xiuying [College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu (China); Department of Materials Science, Sichuan University, Chengdu (China); Zhao, Beijun [Department of Materials Science, Sichuan University, Chengdu (China); Yang, Dingyu; Wangyang, Peihua; Zhu, Xinghua [College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu (China)

2017-02-15

A promising flexible X-ray detector based on inorganic semiconductor PbI{sub 2} crystal is reported. The sliced crystals mechanically cleaved from an as-grown PbI{sub 2} crystal act as the absorber directly converting the impinging X-ray photons to electron hole pairs. Due to the ductile feature of the PbI{sub 2} crystal, the detector can be operated under a highly curved state with the strain on the top surface up to 1.03% and still maintaining effective detection performance. The stable photocurrent and fast response were obtained with the detector repeated bending to a strain of 1.03% for 100 cycles. This work presents an approach for developing efficient and cost-effective PbI{sub 2}-based flexible X-ray detector. Photocurrent responses of the flexible PbI{sub 2} X-ray detector with the strain on the top surface up to 1.03% proposed in this work with the cross sectional structure and curved detector photograph as insets. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

In vivo x-ray phase contrast analyzer-based imaging for longitudinal osteoarthritis studies in guinea pigs

Energy Technology Data Exchange (ETDEWEB)

Coan, Paola [Faculty of Medicine and Institute of Clinical Radiology, Ludwig-Maximilians University, Munich (Germany); Wagner, Andreas; Mollenhauer, Juergen [Department of Orthopaedics of the University of Jena, Rudolf-Elle-Hospital Eisenberg (Germany); Bravin, Alberto; Diemoz, Paul C; Keyrilaeinen, Jani, E-mail: Paola.Coan@physik.uni-muenchen.d [European Synchrotron Radiation Facility (ESRF), Grenoble (France)

2010-12-21

Over the last two decades phase contrast x-ray imaging techniques have been extensively studied for applications in the biomedical field. Published results demonstrate the high capability of these imaging modalities of improving the image contrast of biological samples with respect to standard absorption-based radiography and routinely used clinical imaging techniques. A clear depiction of the anatomic structures and a more accurate disease diagnosis may be provided by using radiation doses comparable to or lower than those used in current clinical methods. In the literature many works show images of phantoms and excised biological samples proving the high sensitivity of the phase contrast imaging methods for in vitro investigations. In this scenario, the applications of the so-called analyzer-based x-ray imaging (ABI) phase contrast technique are particularly noteworthy. The objective of this work is to demonstrate the feasibility of in vivo x-ray ABI phase contrast imaging for biomedical applications and in particular with respect to joint anatomic depiction and osteoarthritis detection. ABI in planar and tomographic modes was performed in vivo on articular joints of guinea pigs in order to investigate the animals with respect to osteoarthritis by using highly monochromatic x-rays of 52 keV and a low noise detector with a pixel size of 47 x 47 {mu}m{sup 2}. Images give strong evidence of the ability of ABI in depicting both anatomic structures in complex systems as living organisms and all known signs of osteoarthritis with high contrast, high spatial resolution and with an acceptable radiation dose. This paper presents the first proof of principle study of in vivo application of ABI. The technical challenges encountered when imaging an animal in vivo are discussed. This experimental study is an important step toward the study of clinical applications of phase contrast x-ray imaging techniques.

Purification and preliminary X-ray crystallographic studies of β-microseminoprotein from human seminal plasma

International Nuclear Information System (INIS)

Kumar, Vijay; Roske, Yvette; Singh, Nagendra; Heinemann, Udo; Singh, Tej P.; Yadav, Savita

2009-01-01

The preliminary X-ray data of β-microseminoprotein isolated from human seminal plasma at 2.4 Å resolution are reported. β-Microseminoprotein (β-MSP) is a small cysteine-rich protein with a molecular mass of 10 kDa. It was first isolated from human seminal plasma and has subsequently been identified from several species. Comparison of the amino-acid sequences of β-MSP proteins suggests that the protein is a rapidly evolving protein. The function of β-MSP is poorly understood. Furthermore, no crystal structure has been reported of any β-MSP; therefore, determination of the crystal structure of β-MSP is the foremost task in order to understand the function of this protein completely. Here, the purification, crystallization and preliminary X-ray diffraction analysis of β-MSP from human seminal plasma are described. The protein was purified using anion-exchange and size-exclusion chromatography and the purified protein was crystallized using 0.1 M ammonium sulfate, 0.1 M HEPES buffer pH 7.0 and 20%(w/v) PEG 3350. The crystals belonged to the tetragonal space group P4 3 22 and contained three β-MSP molecules in the asymmetric unit. X-ray intensity data were collected to 2.4 Å resolution

Optimization of X-ray phase-contrast imaging based on in-line holography

International Nuclear Information System (INIS)

Wu Xizeng; Liu Hong; Yan Aimin

2005-01-01

This paper introduces a newly conceived formalism for clinical in-line phase-contrast X-ray imaging. The new formalism applies not only to ideal 'thin' objects analyzed in previous studies, but also applies to the real-world tissues used in actual clinical practice. Moreover we have identified the four clinically important factors that affect phase-contrast characteristics. These factors are: (1) body part attenuation (2) the spatial coherence of incident X-rays from an X-ray tube (3) the polychromatic nature of the X-ray source and (4) radiation dose to patients for clinical applications. Techniques of phase image-reconstruction based on the new X-ray in-line holography theory are discussed. Numerical simulations are described which were used to validate the theory. The design parameters of an optimal clinical phase-contrast mammographic imaging system which were determined based on the new theory, and validated in the simulations, are presented. The theory, image reconstruction algorithms, and numerical simulation techniques presented in this paper can be applied widely to clinical diagnostic X-ray imaging applications

Expression, crystallization and preliminary X-ray crystallographic analysis of human agmatinase

International Nuclear Information System (INIS)

Kim, Kyoung Hoon; Ahn, Hyung Jun; Kim, Do Jin; Lee, Hyung Ho; Ha, Jun-Yong; Kim, Hye-Kyung; Yoon, Hye-Jin; Suh, Se Won

2005-01-01

Human agmatinase (Ala36–Val352) was overexpressed and crystallized, and X-ray diffraction data were collected to 2.49 Å. Agmatine, which results from the decarboxylation of l-arginine by arginine decarboxylase, is a metabolic intermediate in the biosynthesis of putresine and higher polyamines (spermidine and spermine). Recent studies indicate that agmatine can have several important biochemical effects in humans, ranging from effects on the central nervous system to cell proliferation in cancer and viral replication. Agmatinase catalyses the hydrolysis of agmatine to putresine and urea and is a major target for drug action and development. The human agmatinase gene encodes a 352-residue protein with a putative mitochondrial targeting sequence at the N-terminus. Human agmatinase (residues Ala36–Val352) has been overexpressed as a fusion with both N- and C-terminal purification tags in Escherichia coli and crystallized in the presence of Mn 2+ and 1,6-diaminohexane at 297 K using polyethylene glycol 4000 as a precipitant. X-ray diffraction data were collected at 100 K to 2.49 Å from a flash-frozen crystal. The crystals are tetragonal, belonging to space group P4 2 , with unit-cell parameters a = b = 114.54, c = 125.65 Å, α = β = γ = 90°. Three monomers are likely to be present in the asymmetric unit, giving a crystal volume per protein weight (V M ) of 3.66 Å 3 Da −1 and a solvent content of 66.4%

Image quality and dose analysis for a PA chest X-ray: Comparison between AEC mode acquisition and manual mode using the 10 kVp ‘rule’

International Nuclear Information System (INIS)

Reis, Cláudia; Gonçalves, João; Klompmaker, Corrie; Bárbara, Ana Rita; Bloor, Chloe; Hegarty, Ryan; Lagrange, Tania; Temming, Noëlle; Sønnesyn, Mathilde; Røkeness, Henriette; Yamasathien, Amandine; Hogg, Peter

2014-01-01

Purpose: To compare the image quality and effective dose applying the 10 kVp rule with manual mode acquisition and AEC mode in PA chest X-ray. Method: 68 images (with and without lesions) were acquired using an anthropomorphic chest phantom using a Wolverson Arcoma X-ray unit. These images were compared against a reference image using the 2 alternative forced choice (2AFC) method. The effective dose (E) was calculated using PCXMC software using the exposure parameters and the DAP. The exposure index (lgM provided by Agfa systems) was recorded. Results: Exposure time decreases more when applying the 10 kVp rule with manual mode (50%–28%) when compared with automatic mode (36%–23%). Statistical differences for E between several ionization chambers' combinations for AEC mode were found (p = 0.002). E is lower when using only the right AEC ionization chamber. Considering the image quality there are no statistical differences (p = 0.348) between the different ionization chambers' combinations for AEC mode for images with no lesions. Considering lgM values, it was demonstrated that they were higher when the AEC mode was used compared to the manual mode. It was also observed that lgM values obtained with AEC mode increased as kVp value went up. The image quality scores did not demonstrate statistical significant differences (p = 0.343) for the images with lesions comparing manual with AEC mode. Conclusion: In general the E is lower when manual mode is used. By using the right AEC ionising chamber under the lung the E will be the lowest in comparison to other ionising chambers. The use of the 10 kVp rule did not affect the visibility of the lesions or image quality

Crystallographic information of intermediate phases in binary Mg–X (X=Sn, Y, Sc, Ag alloys

Directory of Open Access Journals (Sweden)

Dongyan Liu

2015-09-01

Full Text Available The compositions and structures of thermodynamically stable or metastable precipitations in binary Mg-X (X=Sn, Y, Sc, Ag alloys are predicted using ab-initio evolutionary algorithm. The geometry optimizations of the predicted intermetallic compounds are carried out in the framework of density functional theory (DFT [1]. A complete list of the optimized crystallographic information (in cif format of the predicted intermetallic phases is presented here. The data is related to “Predictions on the compositions, structures, and mechanical properties of intermediate phases in binary Mg–X (X=Sn, Y, Sc, Ag alloys” by Liu et al. [2].

Effective X-ray elastic constant measurement for in situ stress measurement of biaxially strained AA5754-O

International Nuclear Information System (INIS)

Iadicola, Mark A.; Gnäupel-Herold, Thomas H.

2012-01-01

Accurate measurement of stresses by X-ray diffraction requires accurate X-ray elastic constants. Calibration experiments are one method to determine these for a specific material in a specific condition. In this paper, uniaxial tension experiments are used to investigate the variation of these constants after uniaxial and equal-biaxial plastic deformation for an aluminum alloy (AA5754-O) of interest to the automotive industry. These data are critical for accurate measurement of the biaxial mechanical properties of the material using a recent experimental method combining specialized sheet metal forming equipment with portable X-ray diffraction equipment. The measured effective X-ray elastic constants show some minor variation with increased plastic deformation, and this behavior was found to be consistent for both uniaxially and equal-biaxially strained samples. The use of two average values for effective X-ray elastic constants, one in the rolling direction and one transverse to the rolling direction of the sheet material, is shown to be of sufficient accuracy for the combined tests of interest. Comparison of uniaxial data measured using X-ray diffraction and standard methods show good agreement, and biaxial stress–strain results show good repeatability. Additionally, the calibration data show some non-linear behavior, which is analyzed in regards to crystallographic texture and intergranular stress effects. The non-linear behavior is found to be the result of intergranular stresses based on comparison with additional measurements using other X-ray diffraction equipment and neutron diffraction.

A miniature X-ray tube based on carbon nanotube for an intraoral dental radiography

International Nuclear Information System (INIS)

Kim, Hyun Jin; Park, Han Beom; Lee, Ju Hyuk; Cho, Sung Oh

2016-01-01

The number of human teeth that can be radiographically taken is limited. Moreover, at least two X-ray shots are required to get images of teeth from both sides of the mouth. In order to overcome the disadvantages of conventional dental radiography, a dental radiograph has been proposed in which an X-ray tube is inserted into the mouth while an X-ray detector is placed outside the mouth. The miniature X-ray tube is required small size to insert into the mouth. Recently, we have fabricated a miniature x-ray tube with the diameter of 7 mm using a carbon nanotube (CNT) field. But, commercialized miniature X-ray tube were adopted a thermionic type using tungsten filament. The X-ray tubes adopted thermionic emission has a disadvantage of increasing temperature of x-ray tube. So it need to cooling system to cool x-ray tube. On the other hands, X-ray tubes adopted CNT field emitters don't need cooling systems because electrons are emitted from CNT by applying high voltage without heating. We have developed the miniature x-ray tube that produce x-ray with uniform spatial distribution based on carbon nanotube field emitters. The fabricated miniature x-ray tube can be stably and reliably operated at 50kV without any vacuum pump. The developed miniature X-ray tube was applied for intraoral dental radiography that employs an intra-oral CNT-based miniature X-ray tube and extra-oral X-ray detectors. An X-ray image of many teeth was successfully obtained by a single X-ray shot using the intra-oral miniature X-ray tube system. Furthermore, images of both molar teeth of pig were simultaneously obtained by a single X-ray shot. These results show that the intraoral dental radiography, which employs an intraoral miniature X-ray tube and an extraoral X-ray detector, performs better than conventional dental radiography

A miniature X-ray tube based on carbon nanotube for an intraoral dental radiography

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Jin; Park, Han Beom; Lee, Ju Hyuk; Cho, Sung Oh [KAIST, Daejeon (Korea, Republic of)

2016-05-15

The number of human teeth that can be radiographically taken is limited. Moreover, at least two X-ray shots are required to get images of teeth from both sides of the mouth. In order to overcome the disadvantages of conventional dental radiography, a dental radiograph has been proposed in which an X-ray tube is inserted into the mouth while an X-ray detector is placed outside the mouth. The miniature X-ray tube is required small size to insert into the mouth. Recently, we have fabricated a miniature x-ray tube with the diameter of 7 mm using a carbon nanotube (CNT) field. But, commercialized miniature X-ray tube were adopted a thermionic type using tungsten filament. The X-ray tubes adopted thermionic emission has a disadvantage of increasing temperature of x-ray tube. So it need to cooling system to cool x-ray tube. On the other hands, X-ray tubes adopted CNT field emitters don't need cooling systems because electrons are emitted from CNT by applying high voltage without heating. We have developed the miniature x-ray tube that produce x-ray with uniform spatial distribution based on carbon nanotube field emitters. The fabricated miniature x-ray tube can be stably and reliably operated at 50kV without any vacuum pump. The developed miniature X-ray tube was applied for intraoral dental radiography that employs an intra-oral CNT-based miniature X-ray tube and extra-oral X-ray detectors. An X-ray image of many teeth was successfully obtained by a single X-ray shot using the intra-oral miniature X-ray tube system. Furthermore, images of both molar teeth of pig were simultaneously obtained by a single X-ray shot. These results show that the intraoral dental radiography, which employs an intraoral miniature X-ray tube and an extraoral X-ray detector, performs better than conventional dental radiography.

Unitary bases for x-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Patterson, C.W.; Harter, W.G.; Schneider, W.D.

1979-01-01

A Gelfand basis is used to derive the coefficients of fractional parentage (CFP's) used to calculate intensities for x-ray photoelectron spectroscopy of atoms. Using associated Gelfand bases, we show that it is easy to derive the Racah CFP relations between particles and holes

Measurement of grain size of polycrystalline materials with confocal energy dispersive micro-X-ray diffraction technology based on polycapillary X-ray optics

Energy Technology Data Exchange (ETDEWEB)

Sun, Weiyuan; Liu, Zhiguo [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Sun, Tianxi, E-mail: stx@bnu.edu.cn [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Peng, Song [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Ma, Yongzhong [Center for Disease Control and Prevention of Beijing, Beijing 100013 (China); Li, Fangzuo; Sun, Xuepeng; Ding, Xunliang [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

2014-11-11

The confocal energy dispersive micro-X-ray diffraction (EDMXRD) based on polycapillary X-ray optics was used to determine the grain size of polycrystalline materials. The grain size of a metallographic specimen of nickel base alloy was measured by using the confocal EDMXRD. The experimental results demonstrated that the confocal EDMXRD had potential applications in measuring large grain size.

High resolution X-ray detector for synchrotron-based microtomography

CERN Document Server

Stampanoni, M; Wyss, P; Abela, R; Patterson, B; Hunt, S; Vermeulen, D; Rueegsegger, P

2002-01-01

Synchrotron-based microtomographic devices are powerful, non-destructive, high-resolution research tools. Highly brilliant and coherent X-rays extend the traditional absorption imaging techniques and enable edge-enhanced and phase-sensitive measurements. At the Materials Science Beamline MS of the Swiss Light Source (SLS), the X-ray microtomographic device is now operative. A high performance detector based on a scintillating screen optically coupled to a CCD camera has been developed and tested. Different configurations are available, covering a field of view ranging from 715x715 mu m sup 2 to 7.15x7.15 mm sup 2 with magnifications from 4x to 40x. With the highest magnification 480 lp/mm had been achieved at 10% modulation transfer function which corresponds to a spatial resolution of 1.04 mu m. A low-noise fast-readout CCD camera transfers 2048x2048 pixels within 100-250 ms at a dynamic range of 12-14 bit to the file server. A user-friendly graphical interface gives access to the main parameters needed for ...

Development of online cable eccentricity detection system based on X-ray CCD

International Nuclear Information System (INIS)

Chen Jianzhen; Li Bin; Wei Kaixia; Guo Lanying; Qu Guopu

2008-01-01

An improved technology of online cable eccentricity detection, based on X-ray CCD, greatly improves the measuring precision and the responding speed. The theory of eccentricity measuring based on X-ray CCD, and the structure of an apparatus are described. The apparatus is composed of scanning drive subsystem, X-ray generation components, data acquiring subsystem and high performance computer system. The measuring results are also presented. The features of this cable eccentricity detection technology are compared with the features of other technologies. (authors)

Applications of Hard X-ray Full-Field Transmission X-ray Microscopy at SSRL

International Nuclear Information System (INIS)

Liu, Y.; Andrews, J. C.; Mehta, A.; Pianetta, P.; Meirer, F.; Gil, S. Carrasco; Sciau, P.; Mester, Z.

2011-01-01

State-of-the-art hard x-ray full-field transmission x-ray microscopy (TXM) at beamline 6-2C of Stanford Synchrotron Radiation Lightsource has been applied to various research fields including biological, environmental, and material studies. With the capability of imaging a 32-micron field-of-view at 30-nm resolution using both absorption mode and Zernike phase contrast, the 3D morphology of yeast cells grown in gold-rich media was investigated. Quantitative evaluation of the absorption coefficient was performed for mercury nanoparticles in alfalfa roots exposed to mercury. Combining XANES and TXM, we also performed XANES-imaging on an ancient pottery sample from the Roman pottery workshop at LaGraufesenque (Aveyron).

Applications of Hard X-ray Full-Field Transmission X-ray Microscopy at SSRL

Science.gov (United States)

Liu, Y.; Andrews, J. C.; Meirer, F.; Mehta, A.; Gil, S. Carrasco; Sciau, P.; Mester, Z.; Pianetta, P.

2011-09-01

State-of-the-art hard x-ray full-field transmission x-ray microscopy (TXM) at beamline 6-2C of Stanford Synchrotron Radiation Lightsource has been applied to various research fields including biological, environmental, and material studies. With the capability of imaging a 32-micron field-of-view at 30-nm resolution using both absorption mode and Zernike phase contrast, the 3D morphology of yeast cells grown in gold-rich media was investigated. Quantitative evaluation of the absorption coefficient was performed for mercury nanoparticles in alfalfa roots exposed to mercury. Combining XANES and TXM, we also performed XANES-imaging on an ancient pottery sample from the Roman pottery workshop at LaGraufesenque (Aveyron).

Crystallization and preliminary X-ray characterization of the glpX-encoded class II fructose-1,6-bisphosphatase from Mycobacterium tuberculosis

International Nuclear Information System (INIS)

Gutka, Hiten J.; Franzblau, Scott G.; Movahedzadeh, Farahnaz; Abad-Zapatero, Cele

2011-01-01

The crystallization and preliminary X-ray crystallographic analysis of the glpX-encoded class II fructose-1,6-bisphosphatase from M. tuberculosis in the apo form is reported. Fructose-1,6-bisphosphatase (FBPase; EC 3.1.3.11), which is a key enzyme in gluconeogenesis, catalyzes the hydrolysis of fructose 1,6-bisphosphate to form fructose 6-phosphate and orthophosphate. The present investigation reports the crystallization and preliminary crystallographic studies of the glpX-encoded class II FBPase from Mycobacterium tuberculosis H37Rv. The recombinant protein, which was cloned using an Escherichia coli expression system, was purified and crystallized using the hanging-drop vapor-diffusion method. The crystals diffracted to a resolution of 2.7 Å and belonged to the hexagonal space group P6 1 22, with unit-cell parameters a = b = 131.3, c = 143.2 Å. The structure has been solved by molecular replacement and is currently undergoing refinement

CMOS-sensors for energy-resolved X-ray imaging

International Nuclear Information System (INIS)

Doering, D.; Amar-Youcef, S.; Deveaux, M.; Linnik, B.; Müntz, C.; Stroth, Joachim; Baudot, J.; Dulinski, W.; Kachel, M.

2016-01-01

Due to their low noise, CMOS Monolithic Active Pixel Sensors are suited to sense X-rays with a few keV quantum energy, which is of interest for high resolution X-ray imaging. Moreover, the good energy resolution of the silicon sensors might be used to measure this quantum energy. Combining both features with the good spatial resolution of CMOS sensors opens the potential to build ''color sensitive' X-ray cameras. Taking such colored images is hampered by the need to operate the CMOS sensors in a single photon counting mode, which restricts the photon flux capability of the sensors. More importantly, the charge sharing between the pixels smears the potentially good energy resolution of the sensors. Based on our experience with CMOS sensors for charged particle tracking, we studied techniques to overcome the latter by means of an offline processing of the data obtained from a CMOS sensor prototype. We found that the energy resolution of the pixels can be recovered at the expense of reduced quantum efficiency. We will introduce the results of our study and discuss the feasibility of taking colored X-ray pictures with CMOS sensors

X-ray absorption spectroscopy investigation of structurally modified lithium niobate crystals

International Nuclear Information System (INIS)

Vitova, Tonya

2008-02-01

The type and concentration of impurity centers in different valence states are crucial for tuning the photorefractive properties of doped Lithium Niobate (LN) crystals. X-ray Absorption Spectroscopy (XAS) is an appropriate tool for studying the local structure of impurity centers. XAS combined with absorption in UV/VIS/IR and High Resolution X-ray Emission Spectroscopy (HRXES) provide information about the valence state of the dopant ions in as-grown, reduced or oxidized doped LN crystals. Cu (Cu 1+ and Cu 2+ ) and Fe (Fe 2+ and Fe 3+ ) atoms are found in two different valence states, whereas there are indications for a third Mn valency, in addition to Mn 2+ and Mn 3+ in manganese-doped LN crystals. One of the charge compensation mechanisms during reduction of copper- doped LN crystals is outgassing of oxygen atoms. Cu ions in the reduced crystals have at least two different site symmetries: twofold (Cu 1+ ) and sixfold (Cu 2+ ) coordinated by O atoms. Fe and Mn atoms are coordinated by six O atoms. Cu and Fe ions are found to occupy only Li sites, whereas Mn ions are also incorporated into Li and Nb sites. The refractive index change in LN crystals irradiated with 3 He 2+ ions is caused by structurally disordered centers, where Nb atoms are displaced from normal crystallographic sites and Li or/and O vacancies are present. (orig.)

Semiconductor X-ray detectors

CERN Document Server

Lowe, Barrie Glyn

2014-01-01

Identifying and measuring the elemental x-rays released when materials are examined with particles (electrons, protons, alpha particles, etc.) or photons (x-rays and gamma rays) is still considered to be the primary analytical technique for routine and non-destructive materials analysis. The Lithium Drifted Silicon (Si(Li)) X-Ray Detector, with its good resolution and peak to background, pioneered this type of analysis on electron microscopes, x-ray fluorescence instruments, and radioactive source- and accelerator-based excitation systems. Although rapid progress in Silicon Drift Detectors (SDDs), Charge Coupled Devices (CCDs), and Compound Semiconductor Detectors, including renewed interest in alternative materials such as CdZnTe and diamond, has made the Si(Li) X-Ray Detector nearly obsolete, the device serves as a useful benchmark and still is used in special instances where its large, sensitive depth is essential. Semiconductor X-Ray Detectors focuses on the history and development of Si(Li) X-Ray Detect...

Einstein X-ray observations of M101

International Nuclear Information System (INIS)

Trinchieri, G.; Fabbiano, G.; Romaine, S.

1990-01-01

The Einstein X-ray observations of the face-on spiral galaxy M101 are presented. The global X-ray luminosity L(x) of M101 is about 1.2 x 10 to the 40th ergs/s for D = 7.2 Mpc, consistent with the expected X-ray luminosity of normal spiral galaxies of its optical magnitude. The X-ray emission is mostly due to very luminous individual sources, with L(x) greater than 10 to the 38th ergs/s each, most likely very massive accreting binary systems. The data suggest a deficiency of sources in the luminosity range of L(x) from about 10 to the 37th to about 10 to the 38th ergs/s, which would indicate that the luminosity distribution of the X-ray sources in M101 might be different from that of M31 or M33. 35 refs

Einstein X-ray observations of M101

Science.gov (United States)

Trinchieri, G.; Fabbiano, G.; Romaine, S.

1990-01-01

The Einstein X-ray observations of the face-on spiral galaxy M101 are presented. The global X-ray luminosity L(x) of M101 is about 1.2 x 10 to the 40th ergs/s for D = 7.2 Mpc, consistent with the expected X-ray luminosity of normal spiral galaxies of its optical magnitude. The X-ray emission is mostly due to very luminous individual sources, with L(x) greater than 10 to the 38th ergs/s each, most likely very massive accreting binary systems. The data suggest a deficiency of sources in the luminosity range of L(x) from about 10 to the 37th to about 10 to the 38th ergs/s, which would indicate that the luminosity distribution of the X-ray sources in M101 might be different from that of M31 or M33.

Materials science with SR using x-ray imaging

International Nuclear Information System (INIS)

Kuriyama, Masao

1990-01-01

Some examples of applications of synchrotron radiation to materials science demonstrate the importance of microstructure information within structural as well as functional materials in order to control their properties and quality as designed for industrial purposes. To collect such information, x-ray imaging in quasi real time is required in either the microradiographic mode or the diffraction (in transmission) mode. New measurement technologies based on imaging are applied to polycrystalline materials, single crystal materials and multilayered device materials to illustrate what kind of synchrotron radiation facility is most desirable for materials science and engineering. (author)

Study of caprine bones after moist and dry heat processes by X-ray diffraction

International Nuclear Information System (INIS)

Barbosa, Caroline M.; Azeredo, Soraia R.; Lopes, Ricardo T.; Souza, Sheila M.F.M de

2013-01-01

Bone tissue is a biological material composed of hydroxyapatite (HAp) and collagen matrix. The bone X-ray diffraction (XRD) pattern presents characteristics of the hydroxyapatite crystallography planes. This paper presents the characterization by X-ray diffraction of caprine bone powder pattern and the comparison of this pattern with moist or dry heat cooked bone patterns. The parameters chosen to characterize the X-ray diffraction peaks were: angular position (2θ), full width at half maximumt (FWHM), and relative intensity (I rel ). The X-ray diffraction patterns were obtained with a Shimadzu XRD-6000 diffractometer. The caprine bone XRD pattern revealed a significant correlation of several crystallographic parameters (lattice data) with hydroxyapatite. The profiles of the three bone types analyzed presented differences. The study showed as small angular displacement (decrease of the 2θ angle) of some peaks was observed after moist and dry heat cooking processes. The characterization of bone tissue aimed to contribute to future analysis in the field of archeology. (author)

Study of caprine bones after moist and dry heat processes by X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Barbosa, Caroline M., E-mail: carolmattosb@yahoo.com.br [Instituto de Arqueologia Brasileira (IAB), Belford Roxo, RJ (Brazil); Azeredo, Soraia R.; Lopes, Ricardo T., E-mail: soraia@lin.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/LIN/UFRJ), Rio de Janeiro, RJ (Brazil). Laboratorio de Instrumentacao Nuclear; Souza, Sheila M.F.M de, E-mail: sferraz@ensp.fiocruz.br [Fundacao Oswaldo Cruz (ENSP/FIOCRUZ), Rio de Janeiro, RJ (Brazil). Escola Nacional de Saude Publica Sergio Arouca

2013-07-01

Bone tissue is a biological material composed of hydroxyapatite (HAp) and collagen matrix. The bone X-ray diffraction (XRD) pattern presents characteristics of the hydroxyapatite crystallography planes. This paper presents the characterization by X-ray diffraction of caprine bone powder pattern and the comparison of this pattern with moist or dry heat cooked bone patterns. The parameters chosen to characterize the X-ray diffraction peaks were: angular position (2θ), full width at half maximumt (FWHM), and relative intensity (I{sub rel}). The X-ray diffraction patterns were obtained with a Shimadzu XRD-6000 diffractometer. The caprine bone XRD pattern revealed a significant correlation of several crystallographic parameters (lattice data) with hydroxyapatite. The profiles of the three bone types analyzed presented differences. The study showed as small angular displacement (decrease of the 2θ angle) of some peaks was observed after moist and dry heat cooking processes. The characterization of bone tissue aimed to contribute to future analysis in the field of archeology. (author)

Influence of crystallographic texture in X70 pipeline steels on toughness anisotropy and delamination

Science.gov (United States)

Al-Jabr, Haytham M.

The effects of microstructure and crystallographic texture in four commercially-produced API X70 pipeline steels and their relation to planar anisotropy of toughness and delamination were evaluated. The experimental steels were processed through either a hot strip mill, a Steckel mill, or a compact strip mill. Different processing routes were selected to obtain plates with potential variations in the microstructure and anisotropic characteristics. Tensile and Charpy impact testing were used to evaluate the mechanical properties in three orientations: longitudinal (L), transverse (T) and diagonal (D) with respect to the rolling direction to evaluate mechanical property anisotropy. The yield and tensile strengths were higher in the T orientation and toughness was lower in the D orientation for all plates. Delamination was observed in some of the ductile fracture surfaces of the impact samples. To further study the splitting behavior and effects on impact toughness, a modified impact test (MCVN) specimen with side grooves was designed to intensify induced stresses parallel to the notch root and thus facilitate evaluation of delamination. Scanning electron microscopy combined with electron backscattered diffraction (EBSD) were used to evaluate the grain size, microstructural constituents, and crystallographic texture to determine the factors leading to delamination and the anisotropy in toughness. The ferrite grain size is mainly responsible for the differences in DBTTs between the L and T orientations. The higher DBTT in the D orientation observed in pipeline steels is attributed to crystallographic texture. The higher DBTT in the D direction is due to the higher volume fraction of grains having their {100} planes parallel or close to the primary fracture plane for the D orientation. An equation based on a new "brittleness parameter," based on an assessment of grain orientations based on EBSD data, was developed to predict the changes in DBTTs with respect to sample

The X-ray Telescope for the SWIFT Gamma-Ray Burst Mission

International Nuclear Information System (INIS)

Wells, A.; Abbey, A.F.; Beardmore, A.; Mukerjee, K.; Osborne, J.P.; Watson, D.J.; Willingale, R.; Burrows, D. N.; Hill, J. E.; Nousek, J.A.; Miles, B.J.; Mori, K.; Morris, D.C.; Zugger, M.; Chincarini, G.; Campana, S.; Citterio, O.; Moretti, A.; Tagliaferri, G.; Bosworth, J.

2004-01-01

The X-ray Telescope (XRT) for the SWIFT mission, built by the international consortium from Pennsylvania State University (United States), University of Leicester (UK) and Osservatorio Astronomico di Brera (Italy), is already installed on the SWIFT spacecraft. The XRT has two key functions on SWIFT; to determine locations of GRBs to better than 5 arc seconds within 100 seconds of initial detection of a burst and to measure spectra and light curves of the X-ray afterglow over around four orders of magnitude of decay in the afterglow intensity. This paper summarises the XRT performance, operating modes and sensitivity for the detection of prompt and extended X-ray afterglows from gamma-ray bursts. The performance characteristics have been determined from data taken during the ground calibration campaign at MPE's Panter facility in September 2002

Synchrotron-based X-ray microscopic studies for bioeffects of nanomaterials.

Science.gov (United States)

Zhu, Ying; Cai, Xiaoqing; Li, Jiang; Zhong, Zengtao; Huang, Qing; Fan, Chunhai

2014-04-01

There have been increasing interests in studying biological effects of nanomaterials, which are nevertheless faced up with many challenges due to the nanoscale dimensions and unique chemical properties of nanomaterials. Synchrotron-based X-ray microscopy, an advanced imaging technology with high spatial resolution and excellent elemental specificity, provides a new platform for studying interactions between nanomaterials and living systems. In this article, we review the recent progress of X-ray microscopic studies on bioeffects of nanomaterials in several living systems including cells, model organisms, animals and plants. We aim to provide an overview of the state of the art, and the advantages of using synchrotron-based X-ray microscopy for characterizing in vitro and in vivo behaviors and biodistribution of nanomaterials. We also expect that the use of a combination of new synchrotron techniques should offer unprecedented opportunities for better understanding complex interactions at the nano-biological interface and accounting for unique bioeffects of nanomaterials. Synchrotron-based X-ray microscopy is a non-destructive imaging technique that enables high resolution spatial mapping of metals with elemental level detection methods. This review summarizes the current use and perspectives of this novel technique in studying the biology and tissue interactions of nanomaterials. Copyright © 2014 Elsevier Inc. All rights reserved.

Comparative Study of Various Normal Mode Analysis Techniques Based on Partial Hessians

OpenAIRE

GHYSELS, AN; VAN SPEYBROECK, VERONIQUE; PAUWELS, EWALD; CATAK, SARON; BROOKS, BERNARD R.; VAN NECK, DIMITRI; WAROQUIER, MICHEL

2010-01-01

Standard normal mode analysis becomes problematic for complex molecular systems, as a result of both the high computational cost and the excessive amount of information when the full Hessian matrix is used. Several partial Hessian methods have been proposed in the literature, yielding approximate normal modes. These methods aim at reducing the computational load and/or calculating only the relevant normal modes of interest in a specific application. Each method has its own (dis)advantages and...

Reintroducing Electrostatics into Macromolecular Crystallographic Refinement: Application to Neutron Crystallography and DNA Hydration

OpenAIRE

Fenn, Timothy D.; Schnieders, Michael J.; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S.; Brunger, Axel T.

2011-01-01

Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a prot...

X-ray-based attenuation correction for positron emission tomography/computed tomography scanners.

Science.gov (United States)

Kinahan, Paul E; Hasegawa, Bruce H; Beyer, Thomas

2003-07-01

A synergy of positron emission tomography (PET)/computed tomography (CT) scanners is the use of the CT data for x-ray-based attenuation correction of the PET emission data. Current methods of measuring transmission use positron sources, gamma-ray sources, or x-ray sources. Each of the types of transmission scans involves different trade-offs of noise versus bias, with positron transmission scans having the highest noise but lowest bias, whereas x-ray scans have negligible noise but the potential for increased quantitative errors. The use of x-ray-based attenuation correction, however, has other advantages, including a lack of bias introduced from post-injection transmission scanning, which is an important practical consideration for clinical scanners, as well as reduced scan times. The sensitivity of x-ray-based attenuation correction to artifacts and quantitative errors depends on the method of translating the CT image from the effective x-ray energy of approximately 70 keV to attenuation coefficients at the PET energy of 511 keV. These translation methods are usually based on segmentation and/or scaling techniques. Errors in the PET emission image arise from positional mismatches caused by patient motion or respiration differences between the PET and CT scans; incorrect calculation of attenuation coefficients for CT contrast agents or metallic implants; or keeping the patient's arms in the field of view, which leads to truncation and/or beam-hardening (or x-ray scatter) artifacts. Proper interpretation of PET emission images corrected for attenuation by using the CT image relies on an understanding of the potential artifacts. In cases where an artifact or bias is suspected, careful inspection of all three available images (CT and PET emission with and without attenuation correction) is recommended. Copyright 2003 Elsevier Inc. All rights reserved.

New detection modules for gamma, beta and X-ray cameras

International Nuclear Information System (INIS)

Azman, S.; Bolle, E.; Dang, K.Q.; Dang, W.; Dietzel, K.I.; Froberg, T.; Gaarder, P.E.; Gjaerum, J.A.; Haugen, S.H.; Hellum, G.; Henriksen, J.R.; Johanson, T.M.; Kobbevik, A.; Maehlum, G.; Meier, D.; Mikkelsen, S.; Ninive, I.; Oya, P.; Pavlov, N.; Pettersen, D.M.; Sundal, B.M.; Talebi, J.; Yoshioka, K.

2003-01-01

Full text: Ideas ASA is developing new detection modules for gamma, beta and X-ray cameras. Recent developments focus on modules using various semi-conductor materials (CZT, HgI, Si). The development includes ASIC design, detector module development, and implementation in camera heads. In this presentation we describe the characteristics of important ASICs and its properties in terms of electronic noise, and the modes for measuring signals (switched current modes, sparsified modes, self triggered modes). The ASICs are specific for detectors and applications. We describe recent developments using various semi - conductor materials. We describe important design aspects for medical applications and in life science (SPECT, beta, X-ray cameras)

Building lab-scale x-ray tube based irradiators

International Nuclear Information System (INIS)

Haff, Ron; Jackson, Eric; Gomez, Joseph; Light, Doug; Follett, Peter; Simmons, Greg; Higbee, Brad

2016-01-01

Here we report the use of x-ray tube based irradiators as alternatives to gamma sources for laboratory scale irradiation. Irradiators were designed with sample placement in closest possible proximity to the source, allowing high dose rates for small samples. Designs using 1000 W x-ray tubes in single tube, double tube, and four tube configurations are described, as well as various cabinet construction techniques. Relatively high dose rates were achieved for small samples, demonstrating feasibility for laboratory based irradiators for research purposes. Dose rates of 9.76, 5.45, and 1.7 Gy/min/tube were measured at the center of a 12.7 cm container of instant rice at 100 keV, 70 keV, and 40 keV, respectively. Dose uniformity varies dramatically as the distance from source to container. For 2.54 cm diameter sample containers containing adult Navel Orangeworm, dose rates of 50–60 Gy/min were measured in the four tube system. - Highlights: • X-ray is demonstrated as an alternative to gamma for lab-based irradiation. • Cabinets using one, two, and four 1000 W tubes are reported. • Dose rate of 9.8 Gy/min/tube at the center of a 12.7 cm container of instant rice. • Dose uniformity varies dramatically as the distance from source to container.

Microprocessor-based system for automatic X-ray diffraction and fluorescence

International Nuclear Information System (INIS)

Souza, A.M. de; Carmo, L.C.S. do; Pereira, V.J.E.; Soares, E.A.

1984-01-01

A data acquisition and processing device appropriate for X-ray analysis and goniometer control was built. The Z-80 based system as well as the whole architeture is described. The advantages and new possibilities of the automated instrument as compared to the traditional ones are listed. The X-ray diffraction and fluorescence techniques can take advantage of the automation. (Author) [pt

X-ray filter for x-ray powder diffraction

Science.gov (United States)

Sinsheimer, John Jay; Conley, Raymond P.; Bouet, Nathalie C. D.; Dooryhee, Eric; Ghose, Sanjit

2018-01-23

Technologies are described for apparatus, methods and systems effective for filtering. The filters may comprise a first plate. The first plate may include an x-ray absorbing material and walls defining first slits. The first slits may include arc shaped openings through the first plate. The walls of the first plate may be configured to absorb at least some of first x-rays when the first x-rays are incident on the x-ray absorbing material, and to output second x-rays. The filters may comprise a second plate spaced from the first plate. The second plate may include the x-ray absorbing material and walls defining second slits. The second slits may include arc shaped openings through the second plate. The walls of the second plate may be configured to absorb at least some of second x-rays and to output third x-rays.

Geometrical effects in X-mode scattering

International Nuclear Information System (INIS)

Bretz, N.

1986-10-01

One technique to extend microwave scattering as a probe of long wavelength density fluctuations in magnetically confined plasmas is to consider the launching and scattering of extraordinary (X-mode) waves nearly perpendicular to the field. When the incident frequency is less than the electron cyclotron frequency, this mode can penetrate beyond the ordinary mode cutoff at the plasma frequency and avoid significant distortions from density gradients typical of tokamak plasmas. In the more familiar case, where the incident and scattered waves are ordinary, the scattering is isotropic perpendicular to the field. However, because the X-mode polarization depends on the frequency ratios and the ray angle to the magnetic field, the coupling between the incident and scattered waves is complicated. This geometrical form factor must be unfolded from the observed scattering in order to interpret the scattering due to density fluctuations alone. The geometrical factor is calculated here for the special case of scattering perpendicular to the magnetic field. For frequencies above the ordinary mode cutoff the scattering is relatively isotropic, while below cutoff there are minima in the forward and backward directions which go to zero at approximately half the ordinary mode cutoff density

Development of an X-ray fluorescence holographic measurement system for protein crystals

Energy Technology Data Exchange (ETDEWEB)

Sato-Tomita, Ayana, E-mail: ayana.sato@jichi.ac.jp, E-mail: shibayam@jichi.ac.jp, E-mail: hayashi.koichi@nitech.ac.jp; Shibayama, Naoya, E-mail: ayana.sato@jichi.ac.jp, E-mail: shibayam@jichi.ac.jp, E-mail: hayashi.koichi@nitech.ac.jp; Okabe, Takahiro [Division of Biophysics, Department of Physiology, Jichi Medical University, Yakushiji, Shimotsuke 329-0498 (Japan); Happo, Naohisa [Department of Computer and Network Engineering, Graduate School of Information Sciences, Hiroshima City University, Asa-Minami-Ku, Hiroshima 731-3194 (Japan); Kimura, Koji [Department of Physical Science and Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555 (Japan); Matsushita, Tomohiro [Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Sayo, Hyogo 679-5198 (Japan); Park, Sam-Yong [Drug Design Laboratory, Department of Medical Life Science, Yokohama City University, Suehiro, Tsurumi, Yokohama 230-0045 (Japan); Sasaki, Yuji C. [Department of Advanced Material Science, Graduate School of Frontier Science, The University of Tokyo, Kashiwanoha, Kashiwa 277-8561 (Japan); Hayashi, Kouichi, E-mail: ayana.sato@jichi.ac.jp, E-mail: shibayam@jichi.ac.jp, E-mail: hayashi.koichi@nitech.ac.jp [Department of Physical Science and Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555 (Japan); Frontier Research Institute for Materials Science, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555 (Japan)

2016-06-15

Experimental procedure and setup for obtaining X-ray fluorescence hologram of crystalline metalloprotein samples are described. Human hemoglobin, an α{sub 2}β{sub 2} tetrameric metalloprotein containing the Fe(II) heme active-site in each chain, was chosen for this study because of its wealth of crystallographic data. A cold gas flow system was introduced to reduce X-ray radiation damage of protein crystals that are usually fragile and susceptible to damage. A χ-stage was installed to rotate the sample while avoiding intersection between the X-ray beam and the sample loop or holder, which is needed for supporting fragile protein crystals. Huge hemoglobin crystals (with a maximum size of 8 × 6 × 3 mm{sup 3}) were prepared and used to keep the footprint of the incident X-ray beam smaller than the sample size during the entire course of the measurement with the incident angle of 0°-70°. Under these experimental and data acquisition conditions, we achieved the first observation of the X-ray fluorescence hologram pattern from the protein crystals with minimal radiation damage, opening up a new and potential method for investigating the stereochemistry of the metal active-sites in biomacromolecules.

Review of X-ray Tomography and X-ray Fluorescence Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Shear, Trevor A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-03-16

This literature review will focus on both laboratory and synchrotron based X-ray tomography of materials and highlight the inner workings of these instruments. X-ray fluorescence spectroscopy will also be reviewed and applications of the tandem use of these techniques will be explored. The real world application of these techniques during the internship will also be discussed.

Expression, crystallization and preliminary X-ray crystallographic analysis of human agmatinase

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyoung Hoon; Ahn, Hyung Jun; Kim, Do Jin; Lee, Hyung Ho; Ha, Jun-Yong; Kim, Hye-Kyung; Yoon, Hye-Jin; Suh, Se Won, E-mail: sewonsuh@snu.ac.kr [Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of)

2005-10-01

Human agmatinase (Ala36–Val352) was overexpressed and crystallized, and X-ray diffraction data were collected to 2.49 Å. Agmatine, which results from the decarboxylation of l-arginine by arginine decarboxylase, is a metabolic intermediate in the biosynthesis of putresine and higher polyamines (spermidine and spermine). Recent studies indicate that agmatine can have several important biochemical effects in humans, ranging from effects on the central nervous system to cell proliferation in cancer and viral replication. Agmatinase catalyses the hydrolysis of agmatine to putresine and urea and is a major target for drug action and development. The human agmatinase gene encodes a 352-residue protein with a putative mitochondrial targeting sequence at the N-terminus. Human agmatinase (residues Ala36–Val352) has been overexpressed as a fusion with both N- and C-terminal purification tags in Escherichia coli and crystallized in the presence of Mn{sup 2+} and 1,6-diaminohexane at 297 K using polyethylene glycol 4000 as a precipitant. X-ray diffraction data were collected at 100 K to 2.49 Å from a flash-frozen crystal. The crystals are tetragonal, belonging to space group P4{sub 2}, with unit-cell parameters a = b = 114.54, c = 125.65 Å, α = β = γ = 90°. Three monomers are likely to be present in the asymmetric unit, giving a crystal volume per protein weight (V{sub M}) of 3.66 Å{sup 3} Da{sup −1} and a solvent content of 66.4%.

A study of the Nb3Ge system by Ge K-edge extended x-ray absorption fine structure and x-ray absorption near-edge structure spectroscopy

International Nuclear Information System (INIS)

Saini, N L; Filippi, M; Wu Ziyu; Oyanagi, H; Ihara, H; Iyo, A; Agrestini, S; Bianconi, A

2002-01-01

The local structure of Nb 3 Ge intermetallic superconductor has been studied by Ge K-edge absorption spectroscopy. Extended x-ray absorption fine structure (EXAFS) experiments show two Ge-Nb distances. In addition to the crystallographic distance of ∼2.87 A, there exists a second Ge-Nb distance, shorter than the first by ∼0.2 A, assigned to a phase with short-range symmetry related to local displacements in the Nb-Nb chains. The x-ray absorption near-edge structure (XANES) spectrum has been simulated by full multiple-scattering calculations considering the local displacements determined by the EXAFS analysis. The XANES spectrum has been well reproduced by considering a cluster of 99 atoms within a radius of about 7 A from the central Ge atom and introducing determined local displacements

Kinetic, Spectroscopic, and X-ray Crystallographic Characterization of the Functional E151H Aminopeptidase from Aeromonas proteolytica.

Energy Technology Data Exchange (ETDEWEB)

Bzymek,K.; Moulin, A.; Swierczek, S.; Ringe, D.; Petsko, G.; Holz, R.

2005-01-01

Glutamate151 (E151) has been shown to be catalytically essential for the aminopeptidase from Vibrio proteolyticus (AAP). E151 acts as the general acid/base during the catalytic mechanism of peptide hydrolysis. However, a glutamate residue is not the only residue capable of functioning as a general acid/base during catalysis for dinuclear metallohydrolases. Recent crystallographic characterization of the D-aminopeptidase from Bacillus subtilis (DppA) revealed a histidine residue that resides in an identical position to E151 in AAP. Because the active-site ligands for DppA and AAP are identical, AAP has been used as a model enzyme to understand the mechanistic role of H115 in DppA. Substitution of E151 with histidine resulted in an active AAP enzyme exhibiting a k{sub cat} value of 2.0 min{sup -1}, which is over 2000 times slower than r AAP (4380 min{sup -1}). ITC experiments revealed that Zn{sup II} binds 330 and 3 times more weakly to E151H-AAP compared to r-AAP. UV-vis and EPR spectra of Co{sup II}-loaded E151H-AAP indicated that the first metal ion resides in a hexacoordinate/pentacoordinate equilibrium environment, whereas the second metal ion is six-coordinate. pH dependence of the kinetic parameters k{sub cat} and K{sub m} for the hydrolysis of L-leucine p-nitroanilide (L-pNA) revealed a change in an ionization constant in the enzyme-substrate complex from 5.3 in r-AAP to 6.4 in E151H-AAP, consistent with E151 in AAP being the active-site general acid/base. Proton inventory studies at pH 8.50 indicate the transfer of one proton in the rate-limiting step of the reaction. Moreover, the X-ray crystal structure of [ZnZn(E151H-AAP)] has been solved to 1.9 {angstrom} resolution, and alteration of E151 to histidine does not introduce any major conformational changes to the overall protein structure or the dinuclear Zn{sup II} active site. Therefore, a histidine residue can function as the general acid/base in hydrolysis reactions of peptides and, through analogy of

Crystallization and preliminary X-ray analysis of the stress-response PPM phosphatase RsbX from Bacillus subtilis

International Nuclear Information System (INIS)

Suganuma, Masatoshi; Teh, Aik Hong; Makino, Masatomo; Shimizu, Nobutaka; Kaneko, Tomonori; Hirata, Kunio; Yamamoto, Masaki; Kumasaka, Takashi

2009-01-01

The bacterial PPM phosphatase RsbX from B. subtilis was expressed in E. coli, purified and crystallized. The crystal belonged to space group P1 and diffracted to 1.06 Å resolution. RsbX from Bacillus subtilis is a manganese-dependent PPM phosphatase and negatively regulates the signal transduction of the general stress response by the dephosphorylation of RsbS and RsbR, which are activators of the alternative RNA polymerase σ factor SigB. In order to elucidate the structural–functional relationship of its Ser/Thr protein-phosphorylation mechanism, an X-ray crystallographic diffraction study of RsbX was performed. Recombinant RsbX was expressed in Escherichia coli, purified and crystallized. Crystals were obtained using the sitting-drop vapour-diffusion method and X-ray diffraction data were collected to 1.06 Å resolution with an R merge of 8.1%. The crystals belonged to the triclinic space group P1, with unit-cell parameters a = 33.3, b = 41.7, c = 68.6 Å, α = 98.8, β = 90.0, γ = 108.4°

Improving material identification by combining x-ray and neutron tomography

Science.gov (United States)

LaManna, Jacob M.; Hussey, Daniel S.; Baltic, Eli; Jacobson, David L.

2017-09-01

X-rays and neutrons provide complementary non-destructive probes for the analysis of structure and chemical composition of materials. Contrast differences between the modes arise due to the differences in interaction with matter. Due to the high sensitivity to hydrogen, neutrons excel at separating liquid water or hydrogenous phases from the underlying structure while X-rays resolve the solid structure. Many samples of interest, such as fluid flow in porous materials or curing concrete, are stochastic or slowly changing with time which makes analysis of sequential imaging with X-rays and neutrons difficult as the sample may change between scans. To alleviate this issue, NIST has developed a system for simultaneous X-ray and neutron tomography by orienting a 90 keVpeak micro-focus X-ray tube orthogonally to a thermal neutron beam. This system allows for non-destructive, multimodal tomography of dynamic or stochastic samples while penetrating through sample environment equipment such as pressure and flow vessels. Current efforts are underway to develop methods for 2D histogram based segmentation of reconstructed volumes. By leveraging the contrast differences between X-rays and neutrons, greater histogram peak separation can occur in 2D vs 1D enabling improved material identification.

Ultrafast, laser-based, x-ray science: the dawn of atomic-scale cinematography

International Nuclear Information System (INIS)

Barty, C.P.J.

2000-01-01

The characteristics of ultrafast chirped pulse amplification systems are reviewed. Application of ultrafast chirped pulse amplification to the generation of femtosecond, incoherent, 8-keV line radiation is outlined and the use of femtosecond laser-based, x-rays for novel time-resolved diffraction studies of crystalline dynamics with sub-picosecond temporal resolution and sub-picometer spatial resolution is reviewed in detail. Possible extensions of laser-based, x-ray technology and evaluation of alternative x-ray approaches for time-resolved studies of the atomic scale dynamics are given. (author)

Ultrafast, laser-based, x-ray science: the dawn of atomic-scale cinematography

Energy Technology Data Exchange (ETDEWEB)

Barty, C.P.J. [University of California, Department of Applied Mechanics and Engineering Science, Urey Hall, Mali Code 0339, San Diego, La Jolla, CA (United States)

2000-03-01

The characteristics of ultrafast chirped pulse amplification systems are reviewed. Application of ultrafast chirped pulse amplification to the generation of femtosecond, incoherent, 8-keV line radiation is outlined and the use of femtosecond laser-based, x-rays for novel time-resolved diffraction studies of crystalline dynamics with sub-picosecond temporal resolution and sub-picometer spatial resolution is reviewed in detail. Possible extensions of laser-based, x-ray technology and evaluation of alternative x-ray approaches for time-resolved studies of the atomic scale dynamics are given. (author)

Investigation of coupling of magnetohydrodynamic modes by soft x-ray computer tomography on the WT-3 tokamak

International Nuclear Information System (INIS)

Yoshimura, Satoru; Maekawa, Takashi; Terumichi, Yasushi

2002-01-01

The internal structure of the stationary m=1 and m=2 modes in an ohmic heating plasma and the double m=1 mode structure in a lower hybrid current drive plasma are investigated on the WT-3 tokamak [Maehara et al., Nucl. Fusion 38, 39 (1998)] using computer tomography after the application of the singular value decomposition to the soft x-ray signals. The results show that, in both cases, two coexisting modes have the same frequency and have a fixed mutual phase relation, indicating that two modes are coupled and rotate as one body in the toroidal direction. It is found that the mutual inductance of two loops of helical current filaments for producing magnetic islands always takes the maximum at the experimentally observed positions of two-mode structures. This result means not only that the electromagnetic coupling of two current loops is at the maximum, but also that the two loops are in the dynamically stable position

Development of multi-color scintillator based X-ray image intensifier

International Nuclear Information System (INIS)

Nittoh, Koichi; Konagai, Chikara; Noji, Takashi

2004-01-01

A multi-color scintillator based high-sensitive, wide dynamic range and long-life X-ray image intensifier has been developed. An europium activated Y 2 O 2 S scintillator, emitting red, green and blue photons of different intensities, is utilized as the output fluorescent screen of the intensifier. By combining this image intensifier with a suitably tuned high sensitive color CCD camera, it is possible for a sensitivity of the red color component to become six times higher than that of the conventional image intensifier. Simultaneous emission of a moderate green color and a weak blue color covers different sensitivity regions. This widens the dynamic range, by nearly two orders of ten. With this image intensifier, it is possible to image simultaneously complex objects containing various different X-ray transmission from paper, water or plastic to heavy metals. This high sensitivity intensifier, operated at lower X-ray exposure, causes less degradation of scintillator materials and less colorization of output screen glass, and thus helps achieve a longer lifetime. This color scintillator based image intensifier is being introduced for X-ray inspection in various fields

Growing central axons deprived of normal target neurones by neonatal X-ray irradiation still terminate in a precisely laminated fashion

International Nuclear Information System (INIS)

Laurberg, S.; Hjorth-Simonsen, A.

1977-01-01

Some studies are described on rat pups. The object was to study the fate of axons that normally terminate in a highly selective laminar fashion in the molecular layer of the medial limb of the dentate gyrus of the mammalian cerebral cortex when this is removed by neonatal X-ray irradiation. The rats were shielded with Pb, except for a field above the hippocampus and the dentate gyrus, and exposed to X-rays from a 250 kV source at a distance of 34 cm. (U.K.)

Gamma-Ray Burst Host Galaxies Have "Normal" Luminosities.

Science.gov (United States)

Schaefer

2000-04-10

The galactic environment of gamma-ray bursts can provide good evidence about the nature of the progenitor system, with two old arguments implying that the burst host galaxies are significantly subluminous. New data and new analysis have now reversed this picture: (1) Even though the first two known host galaxies are indeed greatly subluminous, the next eight hosts have absolute magnitudes typical for a population of field galaxies. A detailed analysis of the 16 known hosts (10 with redshifts) shows them to be consistent with a Schechter luminosity function with R*=-21.8+/-1.0, as expected for normal galaxies. (2) Bright bursts from the Interplanetary Network are typically 18 times brighter than the faint bursts with redshifts; however, the bright bursts do not have galaxies inside their error boxes to limits deeper than expected based on the luminosities for the two samples being identical. A new solution to this dilemma is that a broad burst luminosity function along with a burst number density varying as the star formation rate will require the average luminosity of the bright sample (>6x1058 photons s-1 or>1.7x1052 ergs s-1) to be much greater than the average luminosity of the faint sample ( approximately 1058 photons s-1 or approximately 3x1051 ergs s-1). This places the bright bursts at distances for which host galaxies with a normal luminosity will not violate the observed limits. In conclusion, all current evidence points to gamma-ray burst host galaxies being normal in luminosity.

Reintroducing electrostatics into macromolecular crystallographic refinement: application to neutron crystallography and DNA hydration.

Science.gov (United States)

Fenn, Timothy D; Schnieders, Michael J; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S; Brunger, Axel T

2011-04-13

Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints, and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here, we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a protein crystal structure were refined against joint neutron/X-ray diffraction data sets using force fields without electrostatics or with electrostatics. Hydrogen-bond orientation/geometry favors the inclusion of electrostatics. Refinement of Z-DNA with electrostatics leads to a hypothesis for the entropic stabilization of Z-DNA that may partly explain the thermodynamics of converting the B form of DNA to its Z form. Thus, inclusion of electrostatics assists joint neutron/X-ray refinements, especially for placing and orienting hydrogen atoms. Copyright © 2011 Elsevier Ltd. All rights reserved.

Speckle-based at-wavelength metrology of x-ray optics at Diamond Light Source

Science.gov (United States)

Wang, Hongchang; Zhou, Tunhe; Kashyap, Yogesh; Sawhney, Kawal

2017-08-01

To achieve high resolution and sensitivity on the nanometer scale, further development of X-ray optics is required. Although ex-situ metrology provides valuable information about X-ray optics, the ultimate performance of X-ray optics is critically dependent on the exact nature of the working conditions. Therefore, it is equally important to perform in-situ metrology at the optics' operating wavelength (`at-wavelength' metrology) to optimize the performance of X-ray optics and correct and minimize the collective distortions of the upstream beamline optics, e.g. monochromator, windows, etc. Speckle-based technique has been implemented and further improved at Diamond Light Source. We have demonstrated that the angular sensitivity for measuring the slope error of an optical surface can reach an accuracy of two nanoradians. The recent development of the speckle-based at-wavelength metrology techniques will be presented. Representative examples of the applications of the speckle-based technique will also be given - including optimization of X-ray mirrors and characterization of compound refraction lenses. Such a high-precision metrology technique will be extremely beneficial for the manufacture and in-situ alignment/optimization of X-ray mirrors for next-generation synchrotron beamlines.

Simulation study on unfolding methods for diagnostic X-rays and mixed gamma rays

International Nuclear Information System (INIS)

Hashimoto, Makoto; Ohtaka, Masahiko; Ara, Kuniaki; Kanno, Ikuo; Imamura, Ryo; Mikami, Kenta; Nomiya, Seiichiro; Onabe, Hideaki

2009-01-01

A photon detector operating in current mode that can sense X-ray energy distribution has been reported. This detector consists of a row of several segment detectors. The energy distribution is derived using an unfolding technique. In this paper, comparisons of the unfolding techniques among error reduction, spectrum surveillance, and neural network methods are discussed through simulation studies on the detection of diagnostic X-rays and gamma rays emitted by a mixture of 137 Cs and 60 Co. For diagnostic X-ray measurement, the spectrum surveillance and neural network methods appeared promising, while the error reduction method yielded poor results. However, in the case of measuring mixtures of gamma rays, the error reduction method was both sufficient and effective. (author)

Effects of X-ray tube parameters on thickness measure precision in X-ray profile gauge

International Nuclear Information System (INIS)

Miao Jichen; Wu Zhifang; Xing Guilai

2011-01-01

Instantaneous profile gauge technology has been widely used in metallurgy industry because it can on-line get the profile of steel strip. It has characters of high measure precision and wide measure range, but the X-ray tube parameters only can be set few different values during measurement. The relations of thickness measure precision and X-ray tube current, X-ray tube voltage were analyzed. The results show that the X-ray tube current affects the thickness measure precision and the X-ray tube voltage determines the thickness measure range. The method of estimating the X-ray current by thickness measure precision was provided in the end. This method is the base of X-ray source selection and X-ray source parameter's setting in the instantaneous profile gauge. (authors)

Soft x-ray measurements of resistive wall mode behavior in NSTX

Energy Technology Data Exchange (ETDEWEB)

Delgado-Aparicio, L; Bell, R E; Gerhardt, S P; LeBlanc, B; Menard, J; Paul, S; Roquemore, L [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Stutman, D; Tritz, K; Finkenthal, M [Johns Hopkins University, Baltimore, MD 21218 (United States); Sabbagh, S A; Berkery, J W; Levesque, J P [Columbia University, New York, NY 10027 (United States); Lee, K C, E-mail: ldelgado@pppl.gov [University of California at Davis, Davis, CA 95616 (United States)

2011-03-15

A multi-energy soft x-ray (ME-SXR) array is used for the characterization of resistive wall modes (RWMs) in the National Spherical Torus Experiment (NSTX). Modulations in the time history of the ME-SXR emissivity profiles indicate the existence of edge density and core temperature fluctuations in good agreement with the slow evolution of the n = 1 magnetic perturbation measured by the poloidal and radial RWM coils. The characteristic 20-25 Hz frequency in the SXR diagnostics is approximately that of the n = 1 stable RWM, which is also near the measured peak of the resonant field amplification (RFA) and inversely proportional to the wall time. Together with the magnetics, the ME-SXR measurements suggest that in NSTX the RWM is not restricted exclusively to the reactor wall and edge, and that acting with the stabilizing coils on its global structure may result in density and temperature fluctuations that can be taken into account when designing the feedback process.

X-ray electromagnetic application technology

International Nuclear Information System (INIS)

2011-01-01

The investigating committee aimed at research on electromagnetic fields in functional devices and X-ray fibers for efficient coherent X-ray generation and their material science, high-precision manufacturing, particularly for X-ray electromagnetic application technology from January 2006 to December 2008. In this report, we describe our research results, in particular, on the topics of synchrotron radiation and free-electron laser, Saga Synchrotron Project, X-ray waveguides and waveguide-based lens-less hard-X-ray imaging, X-ray nanofocusing for capillaries and zone plates, dispersion characteristics in photonics crystal consisting of periodic atoms for nanometer waveguides, electromagnetic characteristics of grid structures for scattering fields of nano-meter electromagnetic waves and X-rays, FDTD parallel computing of fundamental scattering and attenuation characteristics of X-ray for medical imaging diagnosis, orthogonal relations of electromagnetic fields including evanescent field in dispersive medium. (author)

X-ray reflectivity and surface roughness

International Nuclear Information System (INIS)

Ocko, B.M.

1988-01-01

Since the advent of high brightness synchrotron radiation sources there has been a phenomenal growth in the use of x-rays as a probe of surface structure. The technique of x-ray reflectivity is particularly relevant to electrochemists since it is capable of probing the structure normal to an electrode surface in situ. In this paper the theoretical framework for x-ray reflectivity is reviewed and the results from previous non-electrochemistry measurements are summarized. These measurements are from the liquid/air interface (CCl 4 ), the metal crystal vacuum interface (Au(100)), and from the liquid/solid interface(liquid crystal/silicon). 34 refs., 5 figs

Status of Kharkov X-ray Generator based on Compton Scattering NESTOR

NARCIS (Netherlands)

Zelinsky, A.; Androsov, V.P.; Bulyak, E.V.; Drebot, I.; Gladkikh, P.I.; Grevtsev, V.; Botman, J.I.M.; Ivashchenko, V.; Karnaukhov, I.M.; Lapshin, V.I.; Markov, V.; Mocheshnikov, N.; Mytsykov, A.; Peev, F.A.; Rezaev, A.; Shcherbakov, A.; Skomorkohov, V.; Skyrda, V.; Telegin, Y.; Trotsenko, V.; Tatchyn, R.; Lebedev, B.; Agafonov, A.V.

2004-01-01

Nowadays the sources of the X-rays based on a storage ring with low beam energy and Compton scattering of intense laser beam are under development in several laboratories. In the paper the state-of-art in development and construction of cooperative project of a Kharkov advanced X-ray source NESTOR

A New Generation of X-ray Baggage Scanners Based on a Different Physical Principle

Directory of Open Access Journals (Sweden)

Robert D. Speller

2011-10-01

Full Text Available X-ray baggage scanners play a basic role in the protection of airports, customs, and other strategically important buildings and infrastructures. The current technology of baggage scanners is based on x-ray attenuation, meaning that the detection of threat objects relies on how various objects differently attenuate the x-ray beams going through them. This capability is enhanced by the use of dual-energy x-ray scanners, which make the determination of the x-ray attenuation characteristics of a material more precise by taking images with different x-ray spectra, and combining the information appropriately. However, this still has limitations whenever objects with similar attenuation characteristics have to be distinguished. We describe an alternative approach based on a different x-ray interaction phenomenon, x-ray refraction. Refraction is a familiar phenomenon in visible light (e.g., what makes a straw half immersed in a glass of water appear bent, which also takes place in the x-ray regime, only causing deviations at much smaller angles. Typically, these deviations occur at the boundaries of all objects. We have developed a system that, like other “phase contrast” based instruments, is capable of detecting such deviations, and therefore of creating precise images of the contours of all objects. This complements the material-related information provided by x-ray attenuation, and helps contextualizing the nature of the individual objects, therefore resulting in an increase of both sensitivity (increased detection rate and specificity (reduced rate of false positives of baggage scanners.

Unusual Black Hole Binary LMC X-3: A Transient High-Mass X-Ray Binary That Is Almost Always On?

Science.gov (United States)

Torpin, Trevor J.; Boyd, Patricia T.; Smale, Alan P.; Valencic, Lynne A.

2017-01-01

We have analyzed a rich, multimission, multiwavelength data set from the black hole X-ray binary (BHXB) LMC X-3, covering a new anomalous low state (ALS), during which the source flux falls to an unprecedentedly low and barely detectable level, and a more normal low state. Simultaneous X-ray and UV/optical monitoring data from Swift are combined with pointed observations from the Rossi X-ray Timing Explorer (RXTE) and X-ray Multi- Mirror Mission (XMM-Newton) and light curves from the Monitor of All-Sky X-ray Image (MAXI) instrument to compare the source characteristics during the ALS with those seen during the normal low state. An XMM-Newton spectrum obtained during the ALS can be modeled using an absorbed power law with Gamma = 1.41‚+/- 0.65 and a luminosity of 7.97 x 10(exp 33) erg/s (0.6-5 keV). The Swift X-ray and UV light curves indicate an X-ray lag of approx. 8 days as LMC X-3 abruptly exits the ALS, suggesting that changes in the mass accretion rate from the donor drive the X-ray lag. The normal low state displays an asymmetric profile in which the exit occurs more quickly than the entry, with minimum X-ray flux a factor of approx. 4300 brighter than during the ALS. The UV brightness of LMC X-3 in the ALS is also fainter and less variable than during normal low states. The existence of repeated ALSs in LMC X-3, as well as a comparison with other BHXBs, implies that it is very close to the transient/persistent X-ray source dividing line. We conclude that LMC X-3 is a transient source that is almost always "on."

Radiation processing with high-energy X-rays

International Nuclear Information System (INIS)

Cleland, Marshall R.; Stichelbaut, Frederic

2009-01-01

The physical, chemical or biological characteristics of selected commercial products and materials can be improved by radiation processing. The ionizing energy can be provided by accelerated electrons with energies between 75 keV and 10 MeV, gamma rays from cobalt-60 with average energies of 1.25 MeV or X-rays with maximum energies up to 7.5 MeV. Electron beams are preferred for thin products, which are processed at high speeds. Gamma rays are used for products that are too thick for treatment with electron beams. High-energy X-rays can also be used for these purposes because their penetration in solid materials is similar to or even slightly greater than that of gamma rays. Previously, the use of X-rays had been inhibited by their slower processing rates and higher costs when compared with gamma rays. Since then, the price of cobalt-60 sources has been increased and the radiation intensity from high-energy, high-power X-ray generators has also increased. For facilities requiring at least 2 MCi of cobalt-60, the capital and operating costs of X-ray facilities with equivalent processing rates can be less than that of gamma-ray irradiators. Several high-energy electron beam facilities have been equipped with removable X-ray targets so that irradiation processes can be done with either type of ionizing energy. A new facility is now being built which will be used exclusively in the X-ray mode to sterilize medical products. Operation of this facility will show that high-energy, high-power X-ray generators are practical alternatives to large gamma-ray sources. (author)

Advanced imaging technology using carbon nanotube x ray source

International Nuclear Information System (INIS)

Choi, Hae Young; Seol, Seung Kown; Kim, Jaehoon; Yoo, Seung Hoon; Kim, Jong Uk

2008-01-01

Recently, X ray imaging technology is a useful and leading medical diagnostic tool for healthcare professionals to diagnose disease in human body. CNTs(i.e. carbon nanotubes)are used in many applications like FED, Micro wave amplifier, X ray source, etc. because of its suitable electrical, chemical and physical properties. Specially, CNTs are well used electron emitters for x ray source. Conventionally, thermionic type of tungsten filament x ray tube is widely employed in the field of bio medical and industrial application fields. However, intrinsic problems such as, poor emission efficiency and low imaging resolution cause the limitation of use of the x ray tube. To fulfill the current market requirement specifically for medical diagnostic field, we have developed rather a portable and compact CNT based x ray source in which high imaging resolution is provided. Electron sources used in X ray tubes should be well focused to the anode target for generation of high quality x ray. In this study, Pierce type x ray generation module was tested based its simulation results using by OPERA 3D code. Pierce type module is composed of cone type electrical lens with its number of them and inner angles of them that shows different results with these parameters. And some preliminary images obtained using the CNT x ray source were obtained. The represented images are the finger bone and teeth in human body. It is clear that the trabeculation shape is observed in finger bone. To obtain the finger bone image, tube currents of 250A at 42kV tube voltage was applied. The human tooth image, however, is somewhat unclear because the supplied voltage to the tube was limited to max. 50kV in the system developed. It should be noted that normally 60∼70kV of tube voltage is supplied in dental imaging. Considering these it should be emphasized that if the tube voltage is over 60kV then clearer image is possible. In this paper, we are discussed comparing between these experiment results and

Three-dimensional phase-contrast X-ray microtomography with scanning–imaging X-ray microscope optics

International Nuclear Information System (INIS)

Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio

2013-01-01

A novel three-dimensional X-ray microtomographic micro-imaging system which enables simultaneous measurement of differential phase contrast and absorption contrast has been developed. The optical system consists of a scanning microscope with one-dimensional focusing device and an imaging microscope with one-dimensional objective. A three-dimensional (3D) X-ray tomographic micro-imaging system has been developed. The optical system is based on a scanning–imaging X-ray microscope (SIXM) optics, which is a hybrid system consisting of a scanning microscope optics with a one-dimensional (1D) focusing (line-focusing) device and an imaging microscope optics with a 1D objective. In the SIXM system, each 1D dataset of a two-dimensional (2D) image is recorded independently. An object is illuminated with a line-focused beam. Positional information of the region illuminated by the line-focused beam is recorded with the 1D imaging microscope optics as line-profile data. By scanning the object with the line focus, 2D image data are obtained. In the same manner as for a scanning microscope optics with a multi-pixel detector, imaging modes such as phase contrast and absorption contrast can be arbitrarily configured after the image data acquisition. By combining a tomographic scan method and the SIXM system, quantitative 3D imaging is performed. Results of a feasibility study of the SIXM for 3D imaging are shown

Conversion of electrostatic upper hybrid emissions to electromagnetic O and X mode waves in the Earth's magnetosphere

International Nuclear Information System (INIS)

Budden, K.G.; Jones, D.

1987-01-01

The linear conversion of electrostatic upper hybrid emissions via the Z mode to electromagnetic ordinary (O) mode waves has for some time been invoked for the source of Terrestrial and Saturnian myriametric and Jovian kilometric radiations. The conversion occurs by virtue of the emissions' propagation in concentration gradients, and for it to be efficient it is necessary for the gradient to be normal to the ambient magnetic field. Suitable concentration gradients are believed to occur at the plasmapause and at the magnetopause. Ray theory predicts only O mode production whereas full wave theory in a cold plasma shows that both O and X (extraordinary) mode are produced, their relative intensities depending on the plasma parameters. Full wave theory in a warm plasma, besides yielding more accurate information on the O and X modes also provides an insight into the effect of conversion on the source plasma wave. Results obtained from these three levels of theory are compared using plasma parameters derived from wave experiments on spacecraft

X-Ray Absorption with Transmission X-Ray Microscopes

NARCIS (Netherlands)

de Groot, F.M.F.

2016-01-01

In this section we focus on the use of transmission X-ray microscopy (TXM) to measure the XAS spectra. In the last decade a range of soft X-ray and hard X-ray TXM microscopes have been developed, allowing the measurement of XAS spectra with 10–100 nm resolution. In the hard X-ray range the TXM

Applying x-ray digital imaging to the verification of cadmium in fuel-storage components

International Nuclear Information System (INIS)

Dabbs, R.D.; Cook, D.H.

1997-01-01

The High Flux Isotope Reactor utilizes large underwater fuel-storage arrays to stage irradiated fuel before it is shipped from the facility. Cadmium is required as a thermal neutron absorber in these fuel-storage arrays to produce an acceptable margin of nuclear subcriticality during both normal and off-normal operating conditions. Due to incomplete documentation from the time of their fabrication, the presence of cadmium within two stainless-steel parts of fuel-storage arrays must be experimentally verified before they are reused in new fuel-storage arrays. A cadmium-verification program has been developed in association with the Waste Examination and Assay Facility located at the Oak Ridge national Laboratory to nondestructively examine these older shroud assemblies. The program includes the following elements (1) x-ray analog imaging, (2) x-ray digital imaging, (3) prompt-gamma-ray spectroscopy measurements, and (4) neutron-transmission measurements. X-ray digital imaging utilizes an analog-to-digital convertor to record attenuated x-ray intensities observed on a fluorescent detector by a video camera. These x-ray intensities are utilized in expressions for cadmium thickness based upon x-ray attenuation theory

Interferometric phase-contrast X-ray CT imaging of VX2 rabbit cancer at 35keV X-ray energy

Science.gov (United States)

Takeda, Tohoru; Wu, Jin; Tsuchiya, Yoshinori; Yoneyama, Akio; Lwin, Thet-Thet; Hyodo, Kazuyuki; Itai, Yuji

2004-05-01

Imaging of large objects at 17.7-keV low x-ray energy causes huge x-ray exposure to the objects even using interferometric phase-contrast x-ray CT (PCCT). Thus, we tried to obtain PCCT images at high x-ray energy of 35keV and examined the image quality using a formalin-fixed VX2 rabbit cancer specimen with 15-mm in diameter. The PCCT system consisted of an asymmetrically cut silicon (220) crystal, a monolithic x-ray interferometer, a phase-shifter, an object cell and an x-ray CCD camera. The PCCT at 35 keV clearly visualized various inner structures of VX2 rabbit cancer such as necrosis, cancer, the surrounding tumor vessels, and normal liver tissue. Besides, image-contrast was not degraded significantly. These results suggest that the PCCT at 35 KeV is sufficient to clearly depict the histopathological morphology of VX2 rabbit cancer specimen.

Crystallization and preliminary X-ray crystallographic studies of DnaJ from Streptococcus pneumoniae

International Nuclear Information System (INIS)

Zhao, Shasha; Jin, Li; Niu, Siqiang; Yang, Wei; Zhang, Shaocheng; Guo, Zhen; Zhang, Hongpeng; Huang, Ailong; Yin, Yibing; Wang, Deqiang

2013-01-01

DnaJ from Streptococcus pneumoniae (SpDnaJ) is involved in the infectious disease process and is being developed as a potential vaccine to prevent bacterial infection. Here the expression, purification, crystallization and preliminary crystallographic analysis of SpDnaJ are reported. DnaJ, cooperating with DnaK and GrpE, promotes the folding of unfolded hydrophobic polypeptides, dissociates protein complexes and translocates protein across membranes. Additionally, DnaJ from Streptococcus pneumoniae (SpDnaJ) is involved in the infectious disease process and is being developed as a potential vaccine to prevent bacterial infection. Here the expression, purification, crystallization and preliminary crystallographic analysis of SpDnaJ are reported. The crystals belong to space groups I222 or I2 1 2 1 2 1 and the diffraction resolution is 3.0 Å with unit-cell parameters a = 47.68, b = 104.45, c = 234.57 Å. The crystal most likely contains one molecule in the asymmetric unit, with a V M value of 3.24 Å 3 Da −1 and a solvent content of 62.1%

Studies of oxide-based thin-layered heterostructures by X-ray scattering methods

Energy Technology Data Exchange (ETDEWEB)

Durand, O. [Thales Research and Technology France, Route Departementale 128, F-91767 Palaiseau Cedex (France)]. E-mail: olivier.durand@thalesgroup.com; Rogers, D. [Nanovation SARL, 103 bis rue de Versailles 91400 Orsay (France); Universite de Technologie de Troyes, 10-12 rue Marie Curie, 10010 (France); Teherani, F. Hosseini [Nanovation SARL, 103 bis rue de Versailles 91400 Orsay (France); Andrieux, M. [LEMHE, ICMMOCNRS-UMR 8182, Universite d' Orsay, Batiment 410, 91410 Orsay (France); Modreanu, M. [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland)

2007-06-04

Some X-ray scattering methods (X-ray reflectometry and Diffractometry) dedicated to the study of thin-layered heterostructures are presented with a particular focus, for practical purposes, on the description of fast, accurate and robust techniques. The use of X-ray scattering metrology as a routinely working non-destructive testing method, particularly by using procedures simplifying the data-evaluation, is emphasized. The model-independent Fourier-inversion method applied to a reflectivity curve allows a fast determination of the individual layer thicknesses. We demonstrate the capability of this method by reporting X-ray reflectometry study on multilayered oxide structures, even when the number of the layers constitutive of the stack is not known a-priori. Fast Fourier transform-based procedure has also been employed successfully on high resolution X-ray diffraction profiles. A study of the reliability of the integral-breadth methods in diffraction line-broadening analysis applied to thin layers, in order to determine coherent domain sizes, is also reported. Examples from studies of oxides-based thin-layers heterostructures will illustrate these methods. In particular, X-ray scattering studies performed on high-k HfO{sub 2} and SrZrO{sub 3} thin-layers, a (GaAs/AlOx) waveguide, and a ZnO thin-layer are reported.

Rapid simulation of X-ray transmission imaging for baggage inspection via GPU-based ray-tracing

Science.gov (United States)

Gong, Qian; Stoian, Razvan-Ionut; Coccarelli, David S.; Greenberg, Joel A.; Vera, Esteban; Gehm, Michael E.

2018-01-01

We present a pipeline that rapidly simulates X-ray transmission imaging for arbitrary system architectures using GPU-based ray-tracing techniques. The purpose of the pipeline is to enable statistical analysis of threat detection in the context of airline baggage inspection. As a faster alternative to Monte Carlo methods, we adopt a deterministic approach for simulating photoelectric absorption-based imaging. The highly-optimized NVIDIA OptiX API is used to implement ray-tracing, greatly speeding code execution. In addition, we implement the first hierarchical representation structure to determine the interaction path length of rays traversing heterogeneous media described by layered polygons. The accuracy of the pipeline has been validated by comparing simulated data with experimental data collected using a heterogenous phantom and a laboratory X-ray imaging system. On a single computer, our approach allows us to generate over 400 2D transmission projections (125 × 125 pixels per frame) per hour for a bag packed with hundreds of everyday objects. By implementing our approach on cloud-based GPU computing platforms, we find that the same 2D projections of approximately 3.9 million bags can be obtained in a single day using 400 GPU instances, at a cost of only 0.001 per bag.

Characteristics of Transmission-type Microfocus X-ray Tube based-on Carbon Nanotube Field Emitter

International Nuclear Information System (INIS)

Heo, Sung Hwan; Ihsan, Aamir; Cho, Sung Oh

2007-01-01

A high resolution microfocus x-ray source is widely applied to noninvasive detection for industrial demands, material science and engineering, and to diagnostic study of microbiology and micro-tomography. Carbon nanotube (CNT) is regarded as an excellent electron emitter, which outperforms conventional electron sources in point of brightness. It has been suggested that CNT is used as an electron source of a high resolution x-ray tube according to their low threshold field with atomically sharp geometry, chemically robust structure, and electric conductivity. Several researchers have reported miniaturized x-ray tube based on diode structure and micro x-ray radiography and computed tomography systems using triode types with precise emission control and electrostatic focusing. Especially, a microfocus x-ray source of 30 μm resolution has been demonstrated recently using an elliptical CNT cathode and asymmetrical Eingel lens. However, to increase the spatial resolution of x-ray source, a smaller CNT emitter is desired. Electron focusing optics must be corrected to reduce aberrations. A thin wire tip end can provide a micro-area of CNT substrate, and a magnetic lens and transmission x-ray target are proper to reduce the lens aberration and a focal length. Until now, CNT based microfocus x-ray source with less than 10 um resolution has not been shown. Here we report a microfocus x-ray source with 4.7 μm x-ray focal spot consisted of a conical CNT tip, a single solenoid lens, and a transmission type x-ray target. A magnified x-ray image larger than 230 times was resolved with advantage of microfocused focal spot and transmission x-ray target

Correction method and software for image distortion and nonuniform response in charge-coupled device-based x-ray detectors utilizing x-ray image intensifier

International Nuclear Information System (INIS)

Ito, Kazuki; Kamikubo, Hironari; Yagi, Naoto; Amemiya, Yoshiyuki

2005-01-01

An on-site method of correcting the image distortion and nonuniform response of a charge-coupled device (CCD)-based X-ray detector was developed using the response of the imaging plate as a reference. The CCD-based X-ray detector consists of a beryllium-windowed X-ray image intensifier (Be-XRII) and a CCD as the image sensor. An image distortion of 29% was improved to less than 1% after the correction. In the correction of nonuniform response due to image distortion, subpixel approximation was performed for the redistribution of pixel values. The optimal number of subpixels was also discussed. In an experiment with polystyrene (PS) latex, it was verified that the correction of both image distortion and nonuniform response worked properly. The correction for the 'contrast reduction' problem was also demonstrated for an isotropic X-ray scattering pattern from the PS latex. (author)

Hafnium-Based Contrast Agents for X-ray Computed Tomography.

Science.gov (United States)

Berger, Markus; Bauser, Marcus; Frenzel, Thomas; Hilger, Christoph Stephan; Jost, Gregor; Lauria, Silvia; Morgenstern, Bernd; Neis, Christian; Pietsch, Hubertus; Sülzle, Detlev; Hegetschweiler, Kaspar

2017-05-15

Heavy-metal-based contrast agents (CAs) offer enhanced X-ray absorption for X-ray computed tomography (CT) compared to the currently used iodinated CAs. We report the discovery of new lanthanide and hafnium azainositol complexes and their optimization with respect to high water solubility and stability. Our efforts culminated in the synthesis of BAY-576, an uncharged hafnium complex with 3:2 stoichiometry and broken complex symmetry. The superior properties of this asymmetrically substituted hafnium CA were demonstrated by a CT angiography study in rabbits that revealed excellent signal contrast enhancement.

Quantitative orientational characterization if low - density polyethylene blow films by x-ray and birefringence

International Nuclear Information System (INIS)

Taheri Qazvini, N.; Mohammadi, N.; Ghaffarian, R.; Assempour, H.; Haghighatkish, M.

2002-01-01

The effect of two important parameters of film blowing processes, i.e., take-up ration and blow-up ratio, on the overall orientation of low-density blown films have been investigated using birefringence measurements. Furthermore, by combining x-ray diffraction pole figure analysis and birefringence, the White and Spruiell biaxial orientation functions have been determined for aforementioned sample. Within the range of processing condition studied, increasing take-up ratio, increases orientation in both machine and transverse direction. Upon increasing blow-up ratio, orientation in the transverse direction increases and the overall orientation state approaches to equal biaxial one. Characterization of the crystalline regions by pole figure analysis reveals that a and b crystallographic axes preferentially orientate in the film plane and the direction normal to it, respectively. The amorphous regions do not have any preferential orientation

Development of X-ray excitable luminescent probes for scanning X-ray microscopy

International Nuclear Information System (INIS)

Moronne, M.M.

1999-01-01

Transmission soft X-ray microscopy is now capable of achieving resolutions that are typically 5 times better than the best-visible light microscopes. With expected improvements in zone plate optics, an additional factor of two may be realized within the next few years. Despite the high resolution now available with X-ray microscopes and the high X-ray contrast provided by biological molecules in the soft X-ray region (λ=2-5 nm), molecular probes for localizing specific biological targets have been lacking. To circumvent this problem, X-ray excitable molecular probes are needed that can target unique biological features. In this paper we report our initial results on the development of lanthanide-based fluorescent probes for biological labeling. Using scanning luminescence X-ray microscopy (SLXM, Jacobsen et al., J. Microscopy 172 (1993) 121-129), we show that lanthanide organo-polychelate complexes are sufficiently bright and radiation resistant to be the basis of a new class of X-ray excitable molecular probes capable of providing at least a fivefold improvement in resolution over visible light microscopy. Lanthanide probes, able to bind 80-100 metal ions per molecule, were found to give strong luminescent signals with X-ray doses exceeding 10 8 Gy, and were used to label actin stress fibers and in vitro preparations of polymerized tubulin. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Femtosecond X-ray Absorption Spectroscopy at a Hard X-ray Free Electron Laser

DEFF Research Database (Denmark)

Lemke, Henrik T.; Bressler, Christian; Chen, Lin X.

2013-01-01

X-ray free electron lasers (XFELs) deliver short (current (SASE based) XFELs, they can be used for measuring high......-quality X-ray absorption data and we report femtosecond time-resolved X-ray absorption near-edge spectroscopy (XANES) measurements of a spin-crossover system, iron(II) tris(2,2'-bipyridine) in water. The data indicate that the low-spin to high-spin transition can be modeled by single-exponential kinetics...

The color of X-rays: Spectral X-ray computed tomography using energy sensitive pixel detectors

NARCIS (Netherlands)

Schioppa, E.J.

2014-01-01

Energy sensitive X-ray imaging detectors are produced by connecting a semiconductor sensor to a spectroscopic pixel readout chip. In this thesis, the applicability of such detectors to X-ray Computed Tomography (CT) is studied. A prototype Medipix based silicon detector is calibrated using X-ray

A Study on the Fatigue-Fractured Surface of Normalized SS41 Steel and M.E.F. Dual Phase Steel by an X-ray Diffraction Technique

International Nuclear Information System (INIS)

Oh, Sae Wook; Park, Young Chul; Park, Soo Young; Kim, Deug Jin; Hue, Sun Chul

1996-01-01

This study verified the relationship between fracture mechanics parameters and X-ray parameters for normalized SS41 steel with homogeneous crystal structure and M.E.F. dual phase steel(martensite encapsulated islands of ferrite). The fatigue crack propagation test were carried out and X-ray diffraction technique was applied to fatigue fractured surface. The change in X-ray parameters(residual stress, half-value breadth) according to the depth of fatigue fractured surface were investigated. The depth of maximum plastic zone, W y , were determined on the basis of the distribution of the half-value breadth for normalized SS41 steel and that of the residual stress for M.E.F. dual phase steel. K max could be estimated by the measurement of W y

Anomalous normal mode oscillations in semiconductor microcavities

Energy Technology Data Exchange (ETDEWEB)

Wang, H. [Univ. of Oregon, Eugene, OR (United States). Dept. of Physics; Hou, H.Q.; Hammons, B.E. [Sandia National Labs., Albuquerque, NM (United States)

1997-04-01

Semiconductor microcavities as a composite exciton-cavity system can be characterized by two normal modes. Under an impulsive excitation by a short laser pulse, optical polarizations associated with the two normal modes have a {pi} phase difference. The total induced optical polarization is then expected to exhibit a sin{sup 2}({Omega}t)-like oscillation where 2{Omega} is the normal mode splitting, reflecting a coherent energy exchange between the exciton and cavity. In this paper the authors present experimental studies of normal mode oscillations using three-pulse transient four wave mixing (FWM). The result reveals surprisingly that when the cavity is tuned far below the exciton resonance, normal mode oscillation in the polarization is cos{sup 2}({Omega}t)-like, in contrast to what is expected form the simple normal mode model. This anomalous normal mode oscillation reflects the important role of virtual excitation of electronic states in semiconductor microcavities.

LCC Resonant Multilevel Converter for X-ray Applications

Directory of Open Access Journals (Sweden)

A. M. Pernía

2017-10-01

Full Text Available Medical X-ray appliances use high-voltage power supplies that must be able to work with very different energy requirements. Two techniques can be distinguished in X-ray medical imaging: fluoroscopy and radioscopy. The former involves low power radiation with a long exposure time, while radioscopy requires large power during short radiographic exposure times. Since the converter has to be designed by taking into account the maximum power specification, it will exhibit a poor efficiency when operating at low power levels. Such a problem can be solved by using a new multilevel LCC topology. This topology is based on a classical series-parallel resonant topology, but includes an additional low-voltage auxiliary transformer whose function depends on the X-ray technique considered. When radioscopy operation is selected, the transformer will allow the power to be shared between two full-bridges. If fluoroscopy mode is activated, the auxiliary full bridge is disconnected and the magnetizing inductance of the auxiliary transformer is used to increase the resonant inductor in order to reduce the resonant currents, thus improving the efficiency of the converter.

The 100th Anniversary of X-Ray Crystallography

Directory of Open Access Journals (Sweden)

Kojić-Prodić, B.

2013-07-01

Full Text Available The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them.W. L. BraggThe 100th anniversary of X-ray crystallography dates back to the first X-ray diffraction experiment on a crystal of copper sulphate pentahydrate. Max von Laue designed the theoretical background of the experiment, which was performed by German physicists W. Friedrich and P. Knipping in 1912. At that time, the mathematical formulation of the phenomenon and the fundamental concepts of crystallography were subjects of mineralogy. Altogether, they facilitated the development of methods for determination of the structure of matter at the atomic level. In 1913, father and son Bragg started to develop X-ray structure analysis for determination of crystal structures of simple molecules. Historic examples of structure determination starting from rock salt to complex, biologically important (macromolecules, such as globular proteins haemoglobin and myoglobin, DNA, vitamin B12 and the recent discovery of ribozyme, illustrate the development of X-ray structural analysis. The determination of 3D structures of these molecules by X-ray diffraction had opened new areas of scientific research, such as molecular biophysics, molecular genetics, structural molecular biology, bioinorganic chemistry, organometallic chemistry, and many others. The discovery and development of X-ray crystallography revolutionised our understanding of natural sciences – physics, chemistry, biology, and also science of materials. The scientific community recognised these fundamental achievements (including the discovery of X-rays by awarding twenty-eight Nobel prizes to thirty-nine men and two women. The explosive growth of science and technology in the 20th and 21st centuries had been founded on the detailed knowledge of the three-dimensional structure of molecules, which was the basis for explaining and predicting the physical, chemical, biological and

Tomographic image reconstruction using x-ray phase information

Science.gov (United States)

Momose, Atsushi; Takeda, Tohoru; Itai, Yuji; Hirano, Keiichi

1996-04-01

We have been developing phase-contrast x-ray computed tomography (CT) to make possible the observation of biological soft tissues without contrast enhancement. Phase-contrast x-ray CT requires for its input data the x-ray phase-shift distributions or phase-mapping images caused by an object. These were measured with newly developed fringe-scanning x-ray interferometry. Phase-mapping images at different projection directions were obtained by rotating the object in an x-ray interferometer, and were processed with a standard CT algorithm. A phase-contrast x-ray CT image of a nonstained cancerous tissue was obtained using 17.7 keV synchrotron x rays with 12 micrometer voxel size, although the size of the observation area was at most 5 mm. The cancerous lesions were readily distinguishable from normal tissues. Moreover, fine structures corresponding to cancerous degeneration and fibrous tissues were clearly depicted. It is estimated that the present system is sensitive down to a density deviation of 4 mg/cm3.

Optically detected X-ray absorption spectroscopy measurements as a means of monitoring corrosion layers on copper.

Science.gov (United States)

Dowsett, Mark G; Adriaens, Annemie; Jones, Gareth K C; Poolton, Nigel; Fiddy, Steven; Nikitenko, Sergé

2008-11-15

XANES and EXAFS information is conventionally measured in transmission through the energy-dependent absorption of X-rays or by observing X-ray fluorescence, but secondary fluorescence processes, such as the emission of electrons and optical photons (e.g., 200-1000 nm), can also be used as a carrier of the XAS signatures, providing complementary information such as improved surface specificity. Where the near-visible photons have a shorter range in a material, the data will be more surface specific. Moreover, optical radiation may escape more readily than X-rays through liquid in an environmental cell. Here, we describe a first test of optically detected X-ray absorption spectroscopy (ODXAS) for monitoring electrochemical treatments on copper-based alloys, for example, heritage metals. Artificially made corrosion products deposited on a copper substrate were analyzed in air and in a 1% (w/v) sodium sesquicarbonate solution to simulate typical conservation methods for copper-based objects recovered from marine environments. The measurements were made on stations 7.1 and 9.2 MF (SRS Daresbury, UK) using the mobile luminescence end station (MoLES), supplemented by XAS measurements taken on DUBBLE (BM26 A) at the ESRF. The ODXAS spectra usually contain fine structure similar to that of XAS spectra measured in X-ray fluorescence. Importantly, for the compounds examined, the ODXAS is significantly more surface specific, and >98% characteristic of thin surface layers of 0.5-1.5-microm thickness in cases where X-ray measurements are dominated by the substrate. However, EXAFS and XANES from broadband optical measurements are superimposed on a high background due to other optical emission modes. This produces statistical fluctuations up to double what would be expected from normal counting statistics because the data retain the absolute statistical fluctuation in the original raw count, while losing up to 70% of their magnitude when background is removed. The problem may be

Study of Cr/Sc-based multilayer reflecting mirrors using soft x-ray reflectivity and standing wave-enhanced x-ray fluorescence

Science.gov (United States)

Wu, Meiyi; Burcklen, Catherine; André, Jean-Michel; Guen, Karine Le; Giglia, Angelo; Koshmak, Konstantin; Nannarone, Stefano; Bridou, Françoise; Meltchakov, Evgueni; Rossi, Sébastien de; Delmotte, Franck; Jonnard, Philippe

2017-11-01

We study Cr/Sc-based multilayer mirrors designed to work in the water window range using hard and soft x-ray reflectivity as well as x-ray fluorescence enhanced by standing waves. Samples differ by the elemental composition of the stack, the thickness of each layer, and the order of deposition. This paper mainly consists of two parts. In the first part, the optical performances of different Cr/Sc-based multilayers are reported, and in the second part, we extend further the characterization of the structural parameters of the multilayers, which can be extracted by comparing the experimental data with simulations. The methodology is detailed in the case of Cr/B4C/Sc sample for which a three-layer model is used. Structural parameters determined by fitting reflectivity curve are then introduced as fixed parameters to plot the x-ray standing wave curve, to compare with the experiment, and confirm the determined structure of the stack.

X-ray microtomography

International Nuclear Information System (INIS)

Dunsmuir, J.H.; Ferguson, S.R.; D'Amico, K.L.; Stokes, J.P.

1991-01-01

In this paper the authors describe the application of a new high-resolution X-ray tomographic microscope to the study of porous media. The microscope was designed to exploit the properties of a synchrotron X-ray source to perform three dimensional tomography on millimeter sized objects with micron resolution and has been used in materials science studies with both synchrotron and conventional and synchrotron sources will be compared. In this work the authors have applied the microscope to measure the three dimensional structure of fused bead packs and berea sandstones with micron resolution and have performed preliminary studies of flow in these media with the microscope operated in a digital subtraction radiography mode. Computer graphics techniques have been applied to the data to visually display the structure of the pore body system. Tomographic imaging after flow experiments should detect the structure of the oil-water interface in the pore network and this work is ongoing

Stationary scanning x-ray source based on carbon nanotube field emitters

International Nuclear Information System (INIS)

Zhang, J.; Yang, G.; Cheng, Y.; Gao, B.; Qiu, Q.; Lee, Y.Z.; Lu, J.P.; Zhou, O.

2005-01-01

We report a field emission x-ray source that can generate a scanning x-ray beam to image an object from multiple projection angles without mechanical motion. The key component of the device is a gated carbon nanotube field emission cathode with an array of electron emitting pixels that are individually addressable via a metal-oxide-semiconductor field effect transistor-based electronic circuit. The characteristics of this x-ray source are measured and its imaging capability is demonstrated. The device can potentially lead to a fast data acquisition rate for laminography and tomosynthesis with a simplified experimental setup

Powder X-ray diffraction laboratory, Reston, Virginia

Science.gov (United States)

Piatak, Nadine M.; Dulong, Frank T.; Jackson, John C.; Folger, Helen W.

2014-01-01

The powder x-ray diffraction (XRD) laboratory is managed jointly by the Eastern Mineral and Environmental Resources and Eastern Energy Resources Science Centers. Laboratory scientists collaborate on a wide variety of research problems involving other U.S. Geological Survey (USGS) science centers and government agencies, universities, and industry. Capabilities include identification and quantification of crystalline and amorphous phases, and crystallographic and atomic structure analysis for a wide variety of sample media. Customized laboratory procedures and analyses commonly are used to characterize non-routine samples including, but not limited to, organic and inorganic components in petroleum source rocks, ore and mine waste, clay minerals, and glassy phases. Procedures can be adapted to meet a variety of research objectives.

Center for X-Ray Optics, 1986

International Nuclear Information System (INIS)

1987-07-01

The Center for X-Ray Optics has made substantial progress during the past year on the development of very high resolution x-ray technologies, the generation of coherent radiation at x-ray wavelengths, and, based on these new developments, had embarked on several scientific investigations that would not otherwise have been possible. The investigations covered in this report are topics on x-ray sources, x-ray imaging and applications, soft x-ray spectroscopy, synchrotron radiation, advanced light source and magnet structures for undulators and wigglers

X-ray Pulsars Across the Parameter Space of Luminosity, Accretion Mode, and Spin

Science.gov (United States)

Laycock, Silas

We propose to expand the scope of our successful project providing a multi-satellite library of X-ray Pulsar observations to the community. The library provides high-level products, activity monitoring, pulse-profiles, phased event files, spectra, and a unique pulse-profile modeling interface. The library's scientific footprint will expand in 4 key directions: (1) Update, by processing all new XMM-Newton and Chandra observations (2015-2017) of X-ray Binary Pulsars in the Magellanic Clouds. (2) Expand, by including all archival Suzaku, Swift and NuStar observations, and including Galactic pulsars. (3) Improve, by offering innovative data products that provide deeper insight. (4) Advance, by implementing a new generation of physically motivated emission and pulse-profile models. The library currently includes some 2000 individual RXTE-PCA, 200 Chandra ACIS-I, and 120 XMM-PN observations of the SMC spanning 15 years, creating an unrivaled record of pulsar temporal behavior. In Phase-2, additional observations of SMC pulsars will be added: 221 Chandra (ACIS-S and ACIS-I), 22 XMM-PN, 142 XMM-MOS, 92 Suzaku, 25 NuSTAR, and >10,000 Swift; leveraging our pipeline and analysis techniques already developed. With the addition of 7 Galactic pulsars each having many hundred multisatellite observations, these datasets cover the entire range of variability timescales and accretion regimes. We will model the pulse-profiles using state of the art techniques to parameterize their morphology and obtain the distribution of offsets between magnetic and spin axes, and create samples of profiles under specific accretion modes (whether pencil-beam or fan-beam dominated). These products are needed for the next generation of advances in neutron star theory and modeling. The long-duration of the dataset and “whole-galaxy" nature of the SMC sample make possible a new statistical approach to uncover the duty-cycle distribution and hence population demographics of transient High Mass X-ray

High Resolution Energetic X-ray Imager (HREXI)

Science.gov (United States)

Grindlay, Jonathan

We propose to design and build the first imaging hard X-ray detector system that incorporates 3D stacking of closely packed detector readouts in finely-spaced imaging arrays with their required data processing and control electronics. In virtually all imaging astronomical detectors, detector readout is done with flex connectors or connections that are not vertical but rather horizontal , requiring loss of focal plane area. For high resolution pixel detectors needed for high speed event-based X-ray imaging, from low energy applications (CMOS) with focusing X-ray telescopes, to hard X-ray applications with pixelated CZT for large area coded aperture telescopes, this new detector development offers great promise. We propose to extend our previous and current APRA supported ProtoEXIST program that has developed the first large area imaging CZT detectors and demonstrated their astrophysical capabilities on two successful balloon flight to a next generation High Resolution Energetic X-ray Imager (HREXI), which would incorporate microvia technology for the first time to connect the readout ASIC on each CZT crystal directly to its control and data processing system. This 3-dimensional stacking of detector and readout/control system means that large area (>2m2) imaging detector planes for a High Resolution Wide-field hard X-ray telescope can be built with initially greatly reduced detector gaps and ultimately with no gaps. This increases detector area, efficiency, and simplicity of detector integration. Thus higher sensitivity wide-field imagers will be possible at lower cost. HREXI will enable a post-Swift NASA mission such as the EREXS concept proposed to PCOS to be conducted as a future MIDEX mission. This mission would conduct a high resolution (<2 arcmin) , broad band (5 200 keV) hard X-ray survey of black holes on all scales with ~10X higher sensitivity than Swift. In the current era of Time Domain Astrophysics, such a survey capability, in conjunction with a n

DiSCaMB: a software library for aspherical atom model X-ray scattering factor calculations with CPUs and GPUs.

Science.gov (United States)

Chodkiewicz, Michał L; Migacz, Szymon; Rudnicki, Witold; Makal, Anna; Kalinowski, Jarosław A; Moriarty, Nigel W; Grosse-Kunstleve, Ralf W; Afonine, Pavel V; Adams, Paul D; Dominiak, Paulina Maria

2018-02-01

It has been recently established that the accuracy of structural parameters from X-ray refinement of crystal structures can be improved by using a bank of aspherical pseudoatoms instead of the classical spherical model of atomic form factors. This comes, however, at the cost of increased complexity of the underlying calculations. In order to facilitate the adoption of this more advanced electron density model by the broader community of crystallographers, a new software implementation called DiSCaMB , 'densities in structural chemistry and molecular biology', has been developed. It addresses the challenge of providing for high performance on modern computing architectures. With parallelization options for both multi-core processors and graphics processing units (using CUDA), the library features calculation of X-ray scattering factors and their derivatives with respect to structural parameters, gives access to intermediate steps of the scattering factor calculations (thus allowing for experimentation with modifications of the underlying electron density model), and provides tools for basic structural crystallographic operations. Permissively (MIT) licensed, DiSCaMB is an open-source C++ library that can be embedded in both academic and commercial tools for X-ray structure refinement.

A bromine-based dichroic X-ray polarization analyser

CERN Document Server

Collins, S P; Brown, S D; Thompson, P

2001-01-01

We have demonstrated the advantages offered by dichroic X-ray polarization filters for linear polarization analysis, and describe such a device, based on a dibromoalkane/urea inclusion compound. The polarizer has been successfully tested by analysing the polarization of magnetic diffraction from holmium.

Development of Compact Soft X-ray Source Based on Laser Undulator

CERN Document Server

Kuroda, Ryunosuke; Minamiguchi, S; Saitô, T; Ueyama, D; Washio, Masakazu

2004-01-01

A compact soft X-ray source is required in various research fields such as material and biological science. The laser undulator based on backward Compton scattering has been developed as a compact soft X-ray source for the biological observation at Waseda University. It is performed in a water window region (250eV - 500 eV) using the interaction between 1047 nm Nd:YLF laser and 4 MeV high quality electron beam generated from rf gun system. The range of energy in the water window region has K-shell absorption edges of Oxygen, Carbon and Nitrogen, which mainly constitute of living body. Since the absorption coefficient of water is much smaller than the protein’s coefficient in this range, a dehydration of the specimens is not necessary. As a preliminary experiment, about 300 eV X-ray generation was carried out. As next step, soft X-ray optics with zone plate was proposed for Soft X-ray microscopy. In this conference, we will report details and results of the experiment.

X-ray absorption spectroscopy investigation of structurally modified lithium niobate crystals

Energy Technology Data Exchange (ETDEWEB)

Vitova, Tonya

2008-02-15

The type and concentration of impurity centers in different valence states are crucial for tuning the photorefractive properties of doped Lithium Niobate (LN) crystals. X-ray Absorption Spectroscopy (XAS) is an appropriate tool for studying the local structure of impurity centers. XAS combined with absorption in UV/VIS/IR and High Resolution X-ray Emission Spectroscopy (HRXES) provide information about the valence state of the dopant ions in as-grown, reduced or oxidized doped LN crystals. Cu (Cu{sup 1+} and Cu{sup 2+}) and Fe (Fe{sup 2+} and Fe{sup 3+}) atoms are found in two different valence states, whereas there are indications for a third Mn valency, in addition to Mn{sup 2+} and Mn{sup 3+} in manganese-doped LN crystals. One of the charge compensation mechanisms during reduction of copper- doped LN crystals is outgassing of oxygen atoms. Cu ions in the reduced crystals have at least two different site symmetries: twofold (Cu{sup 1+}) and sixfold (Cu{sup 2+}) coordinated by O atoms. Fe and Mn atoms are coordinated by six O atoms. Cu and Fe ions are found to occupy only Li sites, whereas Mn ions are also incorporated into Li and Nb sites. The refractive index change in LN crystals irradiated with {sup 3}He{sup 2+} ions is caused by structurally disordered centers, where Nb atoms are displaced from normal crystallographic sites and Li or/and O vacancies are present. (orig.)

X-ray luminescence computed tomography imaging via multiple intensity weighted narrow beam irradiation

Science.gov (United States)

Feng, Bo; Gao, Feng; Zhao, Huijuan; Zhang, Limin; Li, Jiao; Zhou, Zhongxing

2018-02-01

The purpose of this work is to introduce and study a novel x-ray beam irradiation pattern for X-ray Luminescence Computed Tomography (XLCT), termed multiple intensity-weighted narrow-beam irradiation. The proposed XLCT imaging method is studied through simulations of x-ray and diffuse lights propagation. The emitted optical photons from X-ray excitable nanophosphors were collected by optical fiber bundles from the right-side surface of the phantom. The implementation of image reconstruction is based on the simulated measurements from 6 or 12 angular projections in terms of 3 or 5 x-ray beams scanning mode. The proposed XLCT imaging method is compared against the constant intensity weighted narrow-beam XLCT. From the reconstructed XLCT images, we found that the Dice similarity and quantitative ratio of targets have a certain degree of improvement. The results demonstrated that the proposed method can offer simultaneously high image quality and fast image acquisition.

InxGa1-xAs obtained from independent target via co-sputtering deposition

International Nuclear Information System (INIS)

Bernal-Correa, R; Torres-Jaramillo, S.; Pulzara-Mora, C.

2017-01-01

This paper is focused on the preparation of InGaAs thin films on GaAs substrates by r.f. magnetron sputtering technique, using the sputtering power as control means for the formation of different stoichiometries. Results of X-ray and Raman spectroscopy allowed corroborating the formation of In x Ga 1-x As in different concentrations, identifying peaks associated with crystallographic planes (X-rays) and characteristic vibrational phonon modes (Raman). An analysis performed with the Secondary Ion Mass Spectroscopy (SIMS) and X-ray Photoelectron Spectroscopy (XPS) techniques, allowed discussing on the composition in each of the layers. Finally, an alternative in obtaining the ternary semiconductor with polycrystalline structure and preferential growth along the direction (111) was demonstrated and generated by a technique different from the epitaxial techniques, which are commonly used for the growth of III-V semiconductors. (paper)

A reaction cell for ambient pressure soft x-ray absorption spectroscopy

Science.gov (United States)

Castán-Guerrero, C.; Krizmancic, D.; Bonanni, V.; Edla, R.; Deluisa, A.; Salvador, F.; Rossi, G.; Panaccione, G.; Torelli, P.

2018-05-01

We present a new experimental setup for performing X-ray Absorption Spectroscopy (XAS) in the soft X-ray range at ambient pressure. The ambient pressure XAS setup is fully compatible with the ultra high vacuum environment of a synchrotron radiation spectroscopy beamline end station by means of ultrathin Si3N4 membranes acting as windows for the X-ray beam and seal of the atmospheric sample environment. The XAS detection is performed in total electron yield (TEY) mode by probing the drain current from the sample with a picoammeter. The high signal/noise ratio achievable in the TEY mode, combined with a continuous scanning of the X-ray energies, makes it possible recording XAS spectra in a few seconds. The first results show the performance of this setup to record fast XAS spectra from sample surfaces exposed at atmospheric pressure, even in the case of highly insulating samples. The use of a permanent magnet inside the reaction cell enables the measurement of X-ray magnetic circular dichroism at ambient pressure.

Automated x-ray television complex for inspecting standard-size dynamic objects

International Nuclear Information System (INIS)

Gusev, E.A.; Luk'yanenko, E.A.; Chelnokov, V.B.; Kuleshov, V.K.; Alkhimov, Yu.V.

1993-01-01

An automated x-ray television complex based on a matrix gas-discharge converter having a large area (2.1 x 1.0 m) for inspecting standard-size freight and containers and for diagnosing industrial articles is presented. The pulsed operating mode of the complex with a 512K digital television storage makes it possible to inspect dynamic objects with a minimum dose load (20--100 μR). 6 refs., 5 figs

Application of X-ray CCD camera in X-ray spot diagnosis of rod-pinch diode

International Nuclear Information System (INIS)

Song Yan; Zhou Ming; Song Guzhou; Ma Jiming; Duan Baojun; Han Changcai; Yao Zhiming

2015-01-01

The pinhole imaging technique is widely used in the measurement of X-ray spot of rod-pinch diode. The X-ray CCD camera, which was composed of film, fiber optic taper and CCD camera, was employed to replace the imaging system based on scintillator, lens and CCD camera in the diagnosis of X-ray spot. The resolution of the X-ray CCD camera was studied. The resolution is restricted by the film and is 5 lp/mm in the test with Pb resolution chart. The frequency is 1.5 lp/mm when the MTF is 0.5 in the test with edge image. The resolution tests indicate that the X-ray CCD camera can meet the requirement of the diagnosis of X-ray spot whose scale is about 1.5 mm when the pinhole imaging magnification is 0.5. At last, the image of X-ray spot was gained and the restoration was implemented in the diagnosis of X-ray spot of rod-pinch diode. (authors)

On the image formation in x-ray radiography using aligned carbon nanofibers

International Nuclear Information System (INIS)

Okuyama, F.

2017-01-01

Evidence is presented that field electrons emitted from vertically-aligned carbon nanofibers (CNFs) yield clearer x-ray images than do thermionic electrons, under the identical electron-optical condition. Specifically, the same sample, an LSI circuit, mounted on the same x-ray chamber could be imaged far more sharply with a CNF emitter than with a thermionic one. It is hypothesized that electrons discharged from CNF tips hit the target to form “discrete focal points” thereon, thereby generating multiple x-ray beams that interplay to form a brilliant, sharply-delineated x-ray image. This hypothesis may stimulate open discussion on how to define the “focal point” for the x-ray imaging using nano-structured electron sources. Also, the improved resolution attained with CNFs might indicate that the heat generation originating in electron-target interactions is not so serious in the present field-emission mode. - Highlights: • Field-emission (FE) x-ray radiography (XR) is based on nanotechnology. • FE-XR surpasses thermionic XR in image resolution and brilliance. • Highly-resolved FE-XR images are due possibly to a discrete array of x-ray spots. • This hypothesis stimulates open discussion on how to define the focal-point in FE-XR.

On the image formation in x-ray radiography using aligned carbon nanofibers

Energy Technology Data Exchange (ETDEWEB)

Okuyama, F., E-mail: okuya@mui.biglobe.ne.jp

2017-04-11

Evidence is presented that field electrons emitted from vertically-aligned carbon nanofibers (CNFs) yield clearer x-ray images than do thermionic electrons, under the identical electron-optical condition. Specifically, the same sample, an LSI circuit, mounted on the same x-ray chamber could be imaged far more sharply with a CNF emitter than with a thermionic one. It is hypothesized that electrons discharged from CNF tips hit the target to form “discrete focal points” thereon, thereby generating multiple x-ray beams that interplay to form a brilliant, sharply-delineated x-ray image. This hypothesis may stimulate open discussion on how to define the “focal point” for the x-ray imaging using nano-structured electron sources. Also, the improved resolution attained with CNFs might indicate that the heat generation originating in electron-target interactions is not so serious in the present field-emission mode. - Highlights: • Field-emission (FE) x-ray radiography (XR) is based on nanotechnology. • FE-XR surpasses thermionic XR in image resolution and brilliance. • Highly-resolved FE-XR images are due possibly to a discrete array of x-ray spots. • This hypothesis stimulates open discussion on how to define the focal-point in FE-XR.

Capability of X-ray diffraction for the study of microstructure of metastable thin films

Directory of Open Access Journals (Sweden)

David Rafaja

2014-11-01

Full Text Available Metastable phases are often used to design materials with outstanding properties, which cannot be achieved with thermodynamically stable compounds. In many cases, the metastable phases are employed as precursors for controlled formation of nanocomposites. This contribution shows how the microstructure of crystalline metastable phases and the formation of nanocomposites can be concluded from X-ray diffraction experiments by taking advantage of the high sensitivity of X-ray diffraction to macroscopic and microscopic lattice deformations and to the dependence of the lattice deformations on the crystallographic direction. The lattice deformations were determined from the positions and from the widths of the diffraction lines, the dependence of the lattice deformations on the crystallographic direction from the anisotropy of the line shift and the line broadening. As an example of the metastable system, the supersaturated solid solution of titanium nitride and aluminium nitride was investigated, which was prepared in the form of thin films by using cathodic arc evaporation of titanium and aluminium in a nitrogen atmosphere. The microstructure of the (Ti,AlN samples under study was tailored by modifying the [Al]/[Ti] ratio in the thin films and the surface mobility of the deposited species.

Wavelet based Image Registration Technique for Matching Dental x-rays

OpenAIRE

P. Ramprasad; H. C. Nagaraj; M. K. Parasuram

2008-01-01

Image registration plays an important role in the diagnosis of dental pathologies such as dental caries, alveolar bone loss and periapical lesions etc. This paper presents a new wavelet based algorithm for registering noisy and poor contrast dental x-rays. Proposed algorithm has two stages. First stage is a preprocessing stage, removes the noise from the x-ray images. Gaussian filter has been used. Second stage is a geometric transformation stage. Proposed work uses two l...

X-ray astronomy

International Nuclear Information System (INIS)

Giacconi, R.; Gursky, H.

1974-01-01

This text contains ten chapters and three appendices. Following an introduction, chapters two through five deal with observational techniques, mechanisms for the production of x rays in a cosmic setting, the x-ray sky and solar x-ray emission. Chapters six through ten include compact x-ray sources, supernova remnants, the interstellar medium, extragalactic x-ray sources and the cosmic x-ray background. Interactions of x rays with matter, units and conversion factors and a catalog of x-ray sources comprise the three appendices. (U.S.)

Benchtop phase-contrast X-ray imaging

Energy Technology Data Exchange (ETDEWEB)

Gundogdu, O. [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)], E-mail: o.gundogdu@surrey.ac.uk; Nirgianaki, E.; Che Ismail, E.; Jenneson, P.M.; Bradley, D.A. [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

2007-12-15

Clinical radiography has traditionally been based on contrast obtained from absorption when X-rays pass through the body. The contrast obtained from traditional radiography can be rather poor, particularly when it comes to soft tissue. A wide range of media of interest in materials science, biology and medicine exhibit very weak absorption contrast, but they nevertheless produce significant phase shifts with X-rays. The use of phase information for imaging purposes is therefore an attractive prospect. Some of the X-ray phase-contrast imaging methods require highly monochromatic plane wave radiation and sophisticated X-ray optics. However, the propagation-based phase-contrast imaging method adapted in this paper is a relatively simple method to implement, essentially requiring only a microfocal X-ray tube and electronic detection. In this paper, we present imaging results obtained from two different benchtop X-ray sources employing the free space propagation method. X-ray phase-contrast imaging provides higher contrast in many samples, including biological tissues that have negligible absorption contrast.

Conformational analysis of phloroglucinols from hypericum Brasiliense by using x-ray diffraction and molecular modeling

Energy Technology Data Exchange (ETDEWEB)

Leal, Katia Z.; Lindgren, Eric B.; Correa, Arthur L., E-mail: kzleal@uol.com.b [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Quimica. Dept. de Fisico-Quimica; Yoneda, Julliane D. [Universidade Federal Fluminense (UFF), Volta Redonda, RJ (Brazil). Polo Universitario de Volta Redonda; Pinheiro, Carlos B. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Fisica; Franca, Hildegardo S. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Faculdade de Farmacia. Dept. de Tecnologia Farmaceutica

2010-07-01

In this work we intend to verify the applicability of a computational methodology to predict structural features of organic compounds with biological activity. We selected three phloroglucinols and compared their calculated conformational data with their X-ray crystallographic structure. The results showed that conformations obtained by conformational analysis with the AM1 method followed by geometry optimization by using the DFT B3LYP/6-31 G(d,p) basis set are in very good agreement with X-ray data, indicating that the methodology employed here seems to be a very useful tool in order to predict the conformational preference for this class of compounds. (author)

Material Discriminated X-Ray CT System by Using New X-Ray Imager with Energy Discriminate Function

Directory of Open Access Journals (Sweden)

Toru Aoki

2008-04-01

Full Text Available Material discriminated X-ray CT system has been constructed by using conventional X-ray tube (white X-ray source and photon-counting X-ray imager as an application with energy band detection. We have already reported material identify X-ray CT using K-shell edge method elsewhere. In this report the principle of material discrimination was adapted the separation of electron-density and atomic number from attenuation coefficient mapping in X-ray CT reconstructed image in two wavelength X-ray CT method using white X-ray source and energy discriminated X-ray imager by using two monochrome X-ray source method. The measurement phantom was prepared as four kinds material rods (Carbon(C, Iron(Fe, Copper(Cu, Titanium(Ti rods of 3mm-diameter inside an aluminum(Al rod of 20mm-diameter. We could observed material discriminated X-ray CT reconstructed image, however, the discrimination properties were not good than two monochrome X-ray CT method. This results was could be explained because X-ray scattering, beam-hardening and so on based on white X-ray source, which could not observe in two monochrome X-ray CT method. However, since our developed CdTe imager can be detect five energy-bands at the same time, we can use multi-band analysis to decrease the least square error margin. We will be able to obtain more high separation in atomic number mapping in X-ray CT reconstructed image by using this system.

Understanding Nickel Thin Film crystallization using X-Ray ...

African Journals Online (AJOL)

The microstructures of these Ni films were studied using X-ray diffractometry technique. The X-ray diffraction (XRD) patterns depicted 100% and 42% relative intensity (RI) peaks identified for normal and helical deposited Ni films but none for the zigzag deposited Ni film. Higher degree of crystallinity of Ni was demonstrated ...

High-Resolution X-ray Emission and X-ray Absorption Spectroscopy

NARCIS (Netherlands)

Groot, F.M.F. de

2000-01-01

In this review, high-resolution X-ray emission and X-ray absorption spectroscopy will be discussed. The focus is on the 3d transition-metal systems. To understand high-resolution X-ray emission and reso-nant X-ray emission, it is first necessary to spend some time discussing the X-ray absorption

Correlating properties and microstructure of YBCO thin films by magnetic X-ray microscopy

Energy Technology Data Exchange (ETDEWEB)

Ruoss, Stephen; Stahl, Claudia; Weigand, Markus; Schuetz, Gisela [Max-Planck-Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Zahn, Patrick; Bayer, Jonas [Max-Planck-Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Research Institute for Innovative Surfaces, FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany); Albrecht, Joachim [Research Institute for Innovative Surfaces, FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany)

2016-07-01

The magnetic flux distribution in high-temperature superconductors namely YBCO has been observed using a novel high-resolution technique based on the X-ray magnetic circular dichroism (XMCD). Therefore, a CoFeB layer is deposited on the superconductor which exhibits a strong XMCD-effect. X-ray absorption measurements with circular polarized radiation allows the analysis of the magnetic flux distribution in the superconductor via the soft-magnetic sensor layer [3,4]. In the total electron yield (TEY) mode of the scanning X-ray microscope (SXM) the surface structure and the magnetic domains can be imaged at the same time. Having obtained such high resolution images, the correlation of magnetic flux penetration and defect structure of YBCO thin films can be analyzed. The measurements have been performed at the scanning X-ray microscope MAXYMUS at Bessy II, HZB Berlin.

Fast photoconductor CdTe detectors for synchrotron x-ray studies

International Nuclear Information System (INIS)

Yoo, Sung Shik; Faurie, J.P.; Huang Qiang; Rodricks, B.

1993-09-01

The Advanced Photon Source will be that brightest source of synchrotron x-rays when it becomes operational in 1996. During normal operation, the ring will be filled with 20 bunches of positrons with an interbunch spacing of 177 ns and a bunch width of 119 ps. To perform experiments with x-rays generated by positrons on these time scales one needs extremely high speed detectors. To achieve the necessary high speed, we are developing MBE-grown CdTe-base photoconductive position sensitive array detectors. The arrays fabricated have 64 pixels with a gap of 100 μm between pixels. The high speed response of the devices was tested using a short pulse laser. X-ray static measurements were performed using an x-ray tube and synchrotron radiation to study the device's response to flux and wavelength changes. This paper presents the response of the devices to some of these tests and discusses different physics aspects to be considered when designing high speed detectors

Micro-beam X-ray fluorescence and absorption imaging techniques at the IAEA Laboratories

International Nuclear Information System (INIS)

Wegrzynek, Dariusz; Markowicz, A.; Bamford, S.; Chinea-Cano, E.; Bogovac, M.

2005-01-01

X-ray tube based, micro-beam X-ray fluorescence scanning spectrometer has been equipped with two energy dispersive X-ray detectors. The two-detector configuration allows for simultaneous collection of X-ray fluorescence (XRF) and transmitted X-ray beam signals with a spatial resolution in the range of 10-50 μm, depending on the X-ray focussing element in use. The XRF signal is collected with a standard, liquid nitrogen cooled Si(Li) detector. The X-ray beam transmitted through the sample is acquired with a thermoelectrically cooled, silicon drift (SD) detector. The data acquisition is carried out in a fully automatic way under control of the SPECTOR-LOCATOR software. The software controls the scanning procedure and X-ray spectra acquisition during the scan. The energy dispersive X-ray spectra collected at every 'pixel' are stored for off-line processing. For selected regions of interest (ROI's), the element maps are constructed and displayed on-line. The spectrometer has been used for mapping elemental distributions and for performing 2D- and 3D-tomograpic imaging of minute objects in X-ray absorption and in X-ray fluorescence mode. A unique feature of the described system is simultaneous utilization of the two detectors, Si(Li) and SD, which adds new options for quantitative analysis and data interpretation. Examples of elemental mapping and 3D tomographic imaging as well as the advanced features of the SPECTOR-LOCATOR measurement control and data acquisition software are presented in this work

Room-temperature serial crystallography using a kinetically optimized microfluidic device for protein crystallization and on-chip X-ray diffraction

Directory of Open Access Journals (Sweden)

Michael Heymann

2014-09-01

Full Text Available An emulsion-based serial crystallographic technology has been developed, in which nanolitre-sized droplets of protein solution are encapsulated in oil and stabilized by surfactant. Once the first crystal in a drop is nucleated, the small volume generates a negative feedback mechanism that lowers the supersaturation. This mechanism is exploited to produce one crystal per drop. Diffraction data are measured, one crystal at a time, from a series of room-temperature crystals stored on an X-ray semi-transparent microfluidic chip, and a 93% complete data set is obtained by merging single diffraction frames taken from different unoriented crystals. As proof of concept, the structure of glucose isomerase was solved to 2.1 Å, demonstrating the feasibility of high-throughput serial X-ray crystallography using synchrotron radiation.

Characterization of continuous and pulsed emission modes of a hybrid micro focus x-ray source for medical imaging applications

International Nuclear Information System (INIS)

Ghani, Muhammad U.; Wong, Molly D.; Ren, Liqiang; Wu, Di; Zheng, Bin; Rong, John X.; Wu, Xizeng; Liu, Hong

2017-01-01

The aim of this study was to quantitatively characterize a micro focus x-ray tube that can operate in both continuous and pulsed emission modes. The micro focus x-ray source (Model L9181-06, Hamamatsu Photonics, Japan) has a varying focal spot size ranging from 16 µm to 50 µm as the source output power changes from 10 to 39 W. We measured the source output, beam quality, focal spot sizes, kV accuracy, spectra shapes and spatial resolution. Source output was measured using an ionization chamber for various tube voltages (kVs) with varying current (µA) and distances. The beam quality was measured in terms of half value layer (HVL), kV accuracy was measured with a non-invasive kV meter, and the spectra was measured using a compact integrated spectrometer system. The focal spot sizes were measured using a slit method with a CCD detector with a pixel pitch of 22 µm. The spatial resolution was quantitatively measured using the slit method with a CMOS flat panel detector with a 50 µm pixel pitch, and compared to the qualitative results obtained by imaging a contrast bar pattern. The focal spot sizes in the vertical direction were smaller than that of the horizontal direction, the impact of which was visible when comparing the spatial resolution values. Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam quality, spectra shape and spatial resolution effects. There were no significantly large differences, thus providing the motivation for future studies to design and develop stable and robust cone beam imaging systems for various diagnostic applications. - Highlights: • A micro focus x-ray source that operates in both continuous and pulse emission modes was quantitatively characterized. • The source output, beam quality, focal spot measurements, kV accuracy, spectra analyses and spatial resolution were measured. • Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam

Characterization of continuous and pulsed emission modes of a hybrid micro focus x-ray source for medical imaging applications

Energy Technology Data Exchange (ETDEWEB)

Ghani, Muhammad U.; Wong, Molly D.; Ren, Liqiang; Wu, Di; Zheng, Bin [Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019 (United States); Rong, John X. [Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX 77030 (United States); Wu, Xizeng [Department of Radiology, University of Alabama at Birmingham, Birmingham, AL 35249 (United States); Liu, Hong, E-mail: liu@ou.edu [Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019 (United States)

2017-05-01

The aim of this study was to quantitatively characterize a micro focus x-ray tube that can operate in both continuous and pulsed emission modes. The micro focus x-ray source (Model L9181-06, Hamamatsu Photonics, Japan) has a varying focal spot size ranging from 16 µm to 50 µm as the source output power changes from 10 to 39 W. We measured the source output, beam quality, focal spot sizes, kV accuracy, spectra shapes and spatial resolution. Source output was measured using an ionization chamber for various tube voltages (kVs) with varying current (µA) and distances. The beam quality was measured in terms of half value layer (HVL), kV accuracy was measured with a non-invasive kV meter, and the spectra was measured using a compact integrated spectrometer system. The focal spot sizes were measured using a slit method with a CCD detector with a pixel pitch of 22 µm. The spatial resolution was quantitatively measured using the slit method with a CMOS flat panel detector with a 50 µm pixel pitch, and compared to the qualitative results obtained by imaging a contrast bar pattern. The focal spot sizes in the vertical direction were smaller than that of the horizontal direction, the impact of which was visible when comparing the spatial resolution values. Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam quality, spectra shape and spatial resolution effects. There were no significantly large differences, thus providing the motivation for future studies to design and develop stable and robust cone beam imaging systems for various diagnostic applications. - Highlights: • A micro focus x-ray source that operates in both continuous and pulse emission modes was quantitatively characterized. • The source output, beam quality, focal spot measurements, kV accuracy, spectra analyses and spatial resolution were measured. • Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam