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Sample records for anomalous small-angle x-ray

  1. Radiation embrittlement studies using anomalous small-angle x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, D. E.; Kestel, B. J.; Seifert, S.; Jemian, P. R.; Odette, G. R.; Klingensmith, D.; Gragg, D.

    1999-12-06

    Anomalous small angle x-ray scattering (ASAXS) was performed on an Fe-O.9 wt.% Cu-1.0 wt.% Mn alloy subjected to annealing or electron irradiation. ASAXS takes advantage of natural variations in the atomic scattering factor which exist at energies very near an element's x-ray absorption edge. By performing systematic SAXS experiments at energies near these absorption edges of the constituent alloy elements it is possible to vary the contrast of scattering centers containing the elements and in doing so quantify scatterer composition. The results of such an analysis for the samples in this work indicate the presence of Cu-rich, Cu{sub 85}Mn{sub 15} precipitates in the alloy. By applying the maximum entropy technique to the scattering data, it was possible to extract size distributions of scattering centers fog the different treatments. The results demonstrate the ability to detect and characterize small (11 {angstrom} radius) scatterers at quite low irradiation damage levels (5x10{sup {minus} 4} displacements per atom).

  2. Radiation embrittlement studies using anomalous small-angle X-ray scattering

    International Nuclear Information System (INIS)

    Anomalous small angle x-ray scattering (ASAXS) was performed on an Fe-O.9 wt.% Cu-1.0 wt.% Mn alloy subjected to annealing or electron irradiation. ASAXS takes advantage of natural variations in the atomic scattering factor which exist at energies very near an element's x-ray absorption edge. By performing systematic SAXS experiments at energies near these absorption edges of the constituent alloy elements it is possible to vary the contrast of scattering centers containing the elements and in doing so quantify scatterer composition. The results of such an analysis for the samples in this work indicate the presence of Cu-rich, Cu85Mn15 precipitates in the alloy. By applying the maximum entropy technique to the scattering data, it was possible to extract size distributions of scattering centers fog the different treatments. The results demonstrate the ability to detect and characterize small (11 A radius) scatterers at quite low irradiation damage levels (5x10-4 displacements per atom)

  3. Application of X-ray absorption spectroscopy and anomalous small angle scattering to RNA polymerase

    International Nuclear Information System (INIS)

    X-ray absorption spectroscopy is ideally suited for the investigation of the electronic structure and the local environment (≤∝5 A) of specific atoms in biomolecules. While the edge region provides information about the valence state of the absorbing atom, the chemical identity of neighboring atoms, and the coordination geometry, the EXAFS region contains information about the number and average distance of neighboring atoms and their relative disorder. The development of sensitive detection methods has allowed studies using near-physiological concentrations (as low as ∝100 μM). With careful choice of model compounds, judicious use of fitting procedures, and consideration of the results of biochemical and other spectrOScopic results, this data has provided pivotal information about the structures of these active sites which store energy in their conformation changes or ligand exchanges. Although the application of anomalous small angle scattering to biomolecules has occurred more recently, it clearly provides a method of determining distances between active sites that are outside the range of X-ray absorption spectroscopy. The wavelength dependence of the X-ray scattering power varies rapidly near the edge of the absorbing atom in both amplitude and phase. This behavior selectively alters the contribution of the absorbing atom to the scattering pattern. The structure-function relationship of the intermediate states provide the key to understanding the mechanisms of these complex molecules. It is this precise structural information about the active sites that is not obtainable by other spectroscopic techniques. Combination of these techniques offers a unique approach to the determination of the organization of active sites in biomolecules, especially metalloenzymes. Application of these methods to the substrate and template binding sites of RNA polymerase which contain zinc atoms demonstrates the versatility of this approach. (orig.)

  4. Comparative anomalous small-angle X-ray scattering study of hotwire and plasma grown amorphous silicon-germanium alloys

    OpenAIRE

    Goerigk, G.; Williamson, D. L.

    2001-01-01

    The nanostructure of hydrogenated amorphous silicon-germanium alloys, a-Si1-xGex:H, prepared by the hotwire deposition technique (x=0.06-0.79) and by the plasma enhanced chemical vapor deposition technique (x=0 and 0.50) was analyzed by anomalous small-angle x-ray scattering experiments. For all alloys with x >0 the Ge component was found to be inhomogeneously distributed with correlation lengths of about 1 nm. A systematic increase of the separated scattering was found due to the increasing ...

  5. Anomalous small-angle X-ray scattering of nanoporous two-phase atomistic models for amorphous silicon–germanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chehaidar, A., E-mail: Abdallah.Chehaidar@fss.rnu.tn

    2015-09-15

    The present work deals with a detailed analysis of the anomalous small-angle X-ray scattering in amorphous silicon–germanium alloy using the simulation technique. We envisage the nanoporous two-phase alloy model consisting in a mixture of Ge-rich and Ge-poor domains and voids at the nanoscale. By substituting Ge atoms for Si atoms in nanoporous amorphous silicon network, compositionally heterogeneous alloys are generated with various composition-contrasts between the two phases. After relaxing the as-generated structure, we compute its radial distribution function, and then we deduce by the Fourier transform technique its anomalous X-ray scattering pattern. Using a smoothing procedure, the computed X-ray scattering patterns are corrected for the termination errors due to the finite size of the model, allowing so a rigorous quantitative analysis of the anomalous small-angle scattering. Our simulation shows that, as expected, the anomalous small-angle X-ray scattering technique is a tool of choice for characterizing compositional heterogeneities coexisting with structural inhomogeneities in an amorphous alloy. Furthermore, the sizes of the compositional nanoheterogeneities, as measured by anomalous small-angle X-ray scattering technique, are X-ray energy independent. A quantitative analysis of the separated reduced anomalous small-angle X-ray scattering, as defined in this work, provided a good estimate of their size.

  6. The distribution of Sr2+ counterions around polyacrylate chains analyzed by anomalous small-angle X-ray scattering

    Science.gov (United States)

    Goerigk, G.; Schweins, R.; Huber, K.; Ballauff, M.

    2004-05-01

    The distribution of Sr counterions around negatively charged sodium polyacrylate chains (NaPA) in aqueous solution was studied by anomalous small-angle X-ray scattering. Different ratios of the concentrations of SrCl2/[NaPA] reveal dramatic changes in the scattering curves. At the lower ratio the scattering curves indicate a coil-like behavior, while at the higher ratio the scattering curves are contracted to smaller q-values, caused by the collapse of the NaPA coil. The form factor of the scattering contribution of the counterions was separated and analyzed. For the scattering curves of the collapsed chains, this analysis agrees with the model of a pearl necklace, consisting of collapsed sphere-like subdomains which are connected by stretched chain segments. An averaged radius of the pearls of 19 nm and a distance between neighbouring pearls close to 60 nm could be established for the collapsed state of the NaPA chains.

  7. In-Situ Anomalous Small-Angle X-ray Scattering Studies of Polymer Electrolyte Membrane Fuel Cell Catalyst Degradation

    Science.gov (United States)

    Gilbert, James Andrew

    Polymer electrolyte membrane fuel cells (PEMFCs) are a promising high efficiency energy conversion technology, but their cost effective implementation, especially for automotive power, has been hindered by degradation of the electrochemically-active surface area (ECA) of the Pt nanoparticle electrocatalysts. While numerous studies using ex-situ post-mortem techniques have provided insight into the effect of operating conditions on ECA loss, the governing mechanisms and underlying processes are not fully understood. Toward the goal of elucidating the electrocatalyst degradation mechanisms, we have followed particle size distribution (PSD) growth evolutions of Pt and Pt-alloy nanoparticle catalysts during potential cycling in an aqueous acidic environment (with and without flow of electrolyte) and in a fuel cell environment using in-situ anomalous small-angle X-ray scattering (ASAXS). The results of this thesis show a surface area loss mechanism of Pt nanoparticles supported on carbon to be predominantly controlled by Pt dissolution, the particle size dependence of Pt dissolution, the loss of dissolved Pt into the membrane and electrolyte, and, to a lesser extent, the re-deposition of dissolved Pt onto larger particles. The relative extent of these loss mechanisms are shown to be dependent on the environment, the temperature, and the potential cycling conditions. Correlation of ASAXS-determined particle growth with both calculated and voltammetrically-determined oxide coverages demonstrates that the oxide coverage is playing a key role in the dissolution process and in the corresponding growth of the mean Pt nanoparticle size and loss of ECA. This understanding potentially reduces the complex changes in PSDs and ECA resulting from various voltage profiles to the response to a single variable, oxide coverage. A better understanding of the degradation mechanisms of Pt and Pt-alloy nanoparticle distributions could lead to more stable electrocatalysts while

  8. In situ anomalous small-angle X-ray scattering studies of platinum nanoparticle fuel cell electrocatalyst degradation.

    Science.gov (United States)

    Gilbert, James A; Kariuki, Nancy N; Subbaraman, Ram; Kropf, A Jeremy; Smith, Matt C; Holby, Edward F; Morgan, Dane; Myers, Deborah J

    2012-09-12

    Polymer electrolyte fuel cells (PEFCs) are a promising high-efficiency energy conversion technology, but their cost-effective implementation, especially for automotive power, has been hindered by degradation of the electrochemically active surface area (ECA) of the Pt nanoparticle electrocatalysts. While numerous studies using ex situ post-mortem techniques have provided insight into the effect of operating conditions on ECA loss, the governing mechanisms and underlying processes are not fully understood. Toward the goal of elucidating the electrocatalyst degradation mechanisms, we have followed Pt nanoparticle growth during potential cycling of the electrocatalyst in an aqueous acidic environment using in situ anomalous small-angle X-ray scattering (ASAXS). ASAXS patterns were analyzed to obtain particle size distributions (PSDs) of the Pt nanoparticle electrocatalysts at periodic intervals during the potential cycling. Oxide coverages reached under the applied potential cycling protocols were both calculated and determined experimentally. Changes in the PSD, mean diameter, and geometric surface area identify the mechanism behind Pt nanoparticle coarsening in an aqueous environment. Over the first 80 potential cycles, the dominant Pt surface area loss mechanism when cycling to 1.0-1.1 V was found to be preferential dissolution or loss of the smallest particles with varying extents of reprecipitation of the dissolved species onto existing particles, resulting in particle growth, depending on potential profile. Correlation of ASAXS-determined particle growth with both calculated and voltammetrically determined oxide coverages demonstrates that the oxide coverage is playing a key role in the dissolution process and in the corresponding growth of the mean Pt nanoparticle size and loss of ECA. This understanding potentially reduces the complex changes in PSD and ECA resulting from various voltage profiles to a response dependent on oxide coverage. PMID:22857132

  9. Systematic Limitations in Concentration Analysis via Anomalous Small-Angle X-ray Scattering in the Small Structure Limit

    OpenAIRE

    Guenter Goerigk; Sebastian Lages; Klaus Huber

    2016-01-01

    Anomalous small angle scattering measurements have been applied to diluted solutions of anionic polyacrylates decorated by specifically-interacting Pb2+ cations, revealing partial collapse of the polyacrylate into pearl-like subdomains with a size on the order of a few nanometers. From the pure-resonant scattering contribution of the Pb2+ cations, and from subsequent analysis of the resonant-invariant, the amount of Pb2+ cations condensed onto the polyanions with respect to the total amount o...

  10. Trends in anomalous small-angle X-ray scattering in grazing incidence for supported nano-alloyed and core-shell metallic nano-particles

    International Nuclear Information System (INIS)

    As atomic structure and morphology of particles are directly correlated to their functional properties, experimental methods probing local and average features of particles at the nano-scale elicit a growing interest. Anomalous small-angle X-ray scattering (ASAXS) is a very attractive technique to investigate the size, shape and spatial distribution of nano-objects embedded in a homogeneous matrix or in porous media. The anomalous variation of the scattering factor close to an absorption edge enables element specific investigations. In the case of supported nano-objects, the use of grazing incidence is necessary to limit the probed depth. The combination of grazing incidence with the anomalous technique provides a powerful new method, anomalous grazing incidence small-angle X-ray scattering (AGISAXS), to disentangle complex chemical patterns in supported multi-component nano-structures. Nevertheless, a proper data analysis requires accurate quantitative measurements associated to an adapted theoretical framework. This paper presents anomalous methods applied to nano-alloys phase separation in the 1-10 nm size range, and focuses on the application of AGISAXS in bimetallic systems: nano-composite films and core-shell supported nano-particles

  11. Systematic Limitations in Concentration Analysis via Anomalous Small-Angle X-ray Scattering in the Small Structure Limit

    Directory of Open Access Journals (Sweden)

    Guenter Goerigk

    2016-03-01

    Full Text Available Anomalous small angle scattering measurements have been applied to diluted solutions of anionic polyacrylates decorated by specifically-interacting Pb2+ cations, revealing partial collapse of the polyacrylate into pearl-like subdomains with a size on the order of a few nanometers. From the pure-resonant scattering contribution of the Pb2+ cations, and from subsequent analysis of the resonant-invariant, the amount of Pb2+ cations condensed onto the polyanions with respect to the total amount of Pb2+ cations in the solvent was estimated. In order to scrutinize systematic limitations in the determination of the chemical concentrations of resonant scattering counterions in the collapsed phase, Monte Carlo simulations have been performed. The simulations are based on structural confinements at variable size in the range of few nanometers, which represent the collapsed subdomains in the polyanions. These confinements were gradually filled to a high degree of the volume fraction with resonant scattering counterions giving access to a resonant-invariant at a variable degree of filling. The simulations revealed in the limit of small structures a significant underestimation of the true degree of filling of the collapsed subdomains when determining chemical concentrations of Pb2+ cations from the resonant invariant.

  12. In-situ study of precipitates in Al–Zn–Mg–Cu alloys using anomalous small-angle x-ray scattering

    Science.gov (United States)

    Chun-Ming, Yang; Feng-Gang, Bian; Bai-Qing, Xiong; Dong-Mei, Liu; Yi-Wen, Li; Wen-Qiang, Hua; Jie, Wang

    2016-06-01

    In the present work, the precipitate compositions and precipitate amounts of these elements (including the size distribution, volume fraction, and inter-precipitate distance) on the Cu-containing 7000 series aluminum alloys (7150 and 7085 Al alloys), are investigated by anomalous small-angle x-ray scattering (ASAXS) at various energies. The scattering intensity of 7150 alloy with T6 aging treatment decreases as the incident x-ray energy approaches the Zn absorption edge from the lower energy side, while scattering intensity does not show a noticeable energy dependence near the Cu absorption edge. Similar results are observed in the 7085 alloy in an aging process (120 °C) by employing in-situ ASAXS measurements, indicating that the precipitate compositions should include Zn element and should not be strongly related to Cu element at the early stage after 10 min. In the aging process, the precipitate particles with an initial average size of ∼ 8 Å increase with aging time at an energy of 9.60 keV, while the increase with a slower rate is observed at an energy of 9.65 keV as near the Zn absorption edge. Project supported by the National Natural Science Foundation of China (Grant Nos. 11005143, 11405259, and 51274046) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry of China (Grant No. [2014]1685).

  13. Probing the extent of the Sr2+ ion condensation to anionic polyacrylate coils: A quantitative anomalous small-angle x-ray scattering study

    Science.gov (United States)

    Goerigk, G.; Huber, K.; Schweins, R.

    2007-10-01

    The shrinking process of anionic sodium polyacrylate (NaPA) chains in aqueous solution induced by Sr2+ counterions was analyzed by anomalous small-angle x-ray scattering. Scattering experiments were performed close to the precipitation threshold of strontium polyacrylate. The pure-resonant scattering contribution, which is related to the structural distribution of the Sr2+ counterions, was used to analyze the extent of Sr2+ condensation onto the polyacrylate coils. A series of four samples with different ratios [Sr2+]/[NaPA] (between 0.451 and 0.464) has been investigated. From the quantitative analysis of the resonant invariant, the amount of Sr cations localized in the collapsed phase was calculated with concentrations v¯ between 0.94×1017 and 2.01×1017cm-3 corresponding to an amount of Sr cations in the collapsed phase between 9% and 23% of the total Sr2+ cations in solution. If compared to the concentration of polyacrylate expressed in moles of monomers [NaPA], a degree of site binding of r =[Sr2+]/[NaPA] between 0.05 and 0.11 was estimated. These values clearly differ from r =0.25, which was established from former light scattering experiments, indicating that the counterion condensation starts before the phase border is reached and increases rather sharply at the border.

  14. Small angle X-ray scattering from hydrating tricalcium silicate

    International Nuclear Information System (INIS)

    The small-angle X-ray scattering technique was used to study the structural evolution of hydrated tricalcium silicate at room temperature. The changes in specific area of the associated porosity and the evolution of density fluctuations in the solid hydrated phase were deduced from the scattering data. A correlation of these variations with the hydration mechanism is tried. (Author)

  15. Small-angle X-ray scattering of solutions

    International Nuclear Information System (INIS)

    The use of synchrotron radiation in small-angle X-ray scattering (SAXS) techniques in biological structural studies is described. The main features of the monochromatic radiation systems and the white radiation systems are considered. The detectors, data acquisition and experimental procedures are briefly described. Experimental results are presented for 1) measurements on dilute solutions and weak scatterers, 2) measurement of conformational transitions, 3) contrast variation experiments, 4) time-resolved measurements and 5) complex contrast variation. (U.K.)

  16. Small angle x-ray scattering with edge-illumination

    Science.gov (United States)

    Modregger, Peter; Cremona, Tiziana P.; Benarafa, Charaf; Schittny, Johannes C.; Olivo, Alessandro; Endrizzi, Marco

    2016-08-01

    Sensitivity to sub-pixel sample features has been demonstrated as a valuable capability of phase contrast x-ray imaging. Here, we report on a method to obtain angular-resolved small angle x-ray scattering distributions with edge-illumination- based imaging utilizing incoherent illumination from an x-ray tube. Our approach provides both the three established image modalities (absorption, differential phase and scatter strength), plus a number of additional contrasts related to unresolved sample features. The complementarity of these contrasts is experimentally validated by using different materials in powder form. As a significant application example we show that the extended complementary contrasts could allow the diagnosis of pulmonary emphysema in a murine model. In support of this, we demonstrate that the properties of the retrieved scattering distributions are consistent with the expectation of increased feature sizes related to pulmonary emphysema. Combined with the simplicity of implementation of edge-illumination, these findings suggest a high potential for exploiting extended sub-pixel contrasts in the diagnosis of lung diseases and beyond.

  17. Magnetic nanoparticles studied by small angle X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Cristiano Luis Pinto [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica. Grupo de Fluidos Complexos; Antonel, Soledad; Negri, Martin [Universidad de Buenos Aires (UBA) (Argentina). Facultad de Ciencias Exactas y Naturales. Dept. de Quimica Inorganica, Analitica y Quimica Fisica

    2011-07-01

    nanoparticles are very interesting because they exhibit magnetic (ferromagnetic) and electrical properties in the same material. Then, the nickel nanoparticles could be used for the development of electroelastic materials. In this case, the electrical conductivity of the material can be strongly dependent on the applied magnetic field, for example the case of nickel metal nanoparticles dispersed in a polymer, resulting in an anisotropic material with combined piezomagnetic and piezoelectric properties. In order to investigate the structural characteristics of cobalt-iron oxides and nickel nanoparticles, powder samples of those magnetic materials were studied by Small-Angle X-Ray Scattering. As will be shown, from the analysis and modeling of the scattering data, structural information could be obtained, enabling a detailed description of the structural properties of the studied samples which could be directly correlated to the magnetic properties. (author)

  18. Small Angle X-ray Scattering for Nanoparticle Research.

    Science.gov (United States)

    Li, Tao; Senesi, Andrew J; Lee, Byeongdu

    2016-09-28

    X-ray scattering is a structural characterization tool that has impacted diverse fields of study. It is unique in its ability to examine materials in real time and under realistic sample environments, enabling researchers to understand morphology at nanometer and angstrom length scales using complementary small and wide angle X-ray scattering (SAXS, WAXS), respectively. Herein, we focus on the use of SAXS to examine nanoscale particulate systems. We provide a theoretical foundation for X-ray scattering, considering both form factor and structure factor, as well as the use of correlation functions, which may be used to determine a particle's size, size distribution, shape, and organization into hierarchical structures. The theory is expanded upon with contemporary use cases. Both transmission and reflection (grazing incidence) geometries are addressed, as well as the combination of SAXS with other X-ray and non-X-ray characterization tools. We conclude with an examination of several key areas of research where X-ray scattering has played a pivotal role, including in situ nanoparticle synthesis, nanoparticle assembly, and operando studies of catalysts and energy storage materials. Throughout this review we highlight the unique capabilities of X-ray scattering for structural characterization of materials in their native environment.

  19. Small angle neutron scattering and small angle X-ray scattering studies of platinum-loaded carbon foams

    Indian Academy of Sciences (India)

    P U Sastry; V K Aswal; A G Wagh

    2008-11-01

    The morphology of carbon nanofoam samples comprising platinum nanoparticles dispersed in the matrix was characterized by small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) techniques. Results show that the structure of pores of carbon matrix exhibits a mass (pore) fractal nature and the average radius of the platinum particles is about 2.5 nm. The fractal dimension as well as the size distribution parameters of platinum particles varies markedly with the platinum content and annealing temperature. Transmission electron micrographs of the samples corroborate the SANS and SAXS results.

  20. Small-Angle X-ray Scattering Screening Complements Conventional Biophysical Analysis

    DEFF Research Database (Denmark)

    Tian, Xinsheng; Langkilde, Annette Eva; Thorolfsson, Matthias;

    2014-01-01

    introduce small-angle X-ray scattering (SAXS) to characterize antibody solution behavior, which strongly complements conventional biophysical analysis. First, we apply a variety of conventional biophysical techniques for the evaluation of structural, conformational, and colloidal stability and report...

  1. In situ microfluidic dialysis for biological small-angle X-ray scattering

    DEFF Research Database (Denmark)

    Skou, Magda; Skou, Soren; Jensen, Thomas Glasdam;

    2014-01-01

    Owing to the demand for low sample consumption and automated sample changing capabilities at synchrotron small-angle X-ray (solution) scattering (SAXS) beamlines, X-ray microfluidics is receiving continuously increasing attention. Here, a remote-controlled microfluidic device is presented for sim...

  2. 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.

  3. Small angle X ray diffraction investigation of twinned opal_like structures

    NARCIS (Netherlands)

    Samusev, A.K.; Sinev, I.S.; Samusev, K.B.; Rybin, M.V.; Mistonov, A.A.; Grigoryeva, N.A.; Grigoriev, S.V.; Petukhov, A.V.; Byelov, D.; Trofimova, E.Y.; Kurdyukov, D.A.; Golubev, V.G.; Limonov, M.F.

    2012-01-01

    Small angle X ray diffraction from synthetic opal films has been investigated as a function of the orientation of the sample. All the observed (hkl) diffraction reflections have been interpreted. The reconstruct tion of the reciprocal lattice of the studied opal films has been carried out. The diffr

  4. Small angle X-ray scattering study of calreticulin reveals conformational plasticity

    DEFF Research Database (Denmark)

    Toft, Katrine Nørgaard; Larsen, Nanna; Jørgensen, Flemming Steen;

    2008-01-01

    Calreticulin plays a central role in vital cell processes such as protein folding, Ca(2+) homeostasis and immunogenicity. Even so, only limited three-dimensional structural information is presently available. We present a series of Small-Angle X-ray Scattering data on human placenta calreticulin...... the functional consequences of the conformational plasticity of the calreticulin P-domain....

  5. Investigation of nanoscale structures by small-angle X-ray scattering in a radiochromic dosimeter

    DEFF Research Database (Denmark)

    Skyt, Peter Sandegaard; Jensen, Grethe Vestergaard; Wahlstedt, Isak Hannes;

    2014-01-01

    This study examines the nanoscale structures in a radiochromic dosimeter that was based on leuco-malachite-green dye and the surfactant sodium dodecyl sulfate (SDS) suspended in a gelatin matrix. Small-angle X-ray scattering was used to investigate the structures of a range of compositions of the...

  6. Counterion Distribution Around Protein-SNAs probed by Small-angle X-ray scattering

    Science.gov (United States)

    Krishnamoorthy, Kurinji; Bedzyk, Michael; Kewalramani, Sumit; Moreau, Liane; Mirkin, Chad

    Protein-DNA conjugates couple the advanced cell transfection capabilities of spherical DNA architecture and the biocompatible enzymatic activity of a protein core to potentially create therapeutic agents with dual functionality. An understanding of their stabilizing ionic environment is crucial to better understand and predict their properties. Here, we use Small-angle X-ray scattering techniques to decipher the structure of the counterion cloud surrounding these DNA coated nanoparticles. Through the use of anomalous scattering techniques we have mapped the local concentrations of Rb+ ions in the region around the Protein-DNA constructs. These results are further corroborated with simulations using a geometric model for the excess charge density as function of radial distance from the protein core. Further, we investigate the influence of solution ionic strength on the structure of the DNA corona and demonstrate a reduction in the extension of the DNA corona with increasing concentration of NaCl in solution for the case of both single and double stranded DNA shells. Our work reveals the distribution of counterions in the vicinity of Protein-DNA conjugates and decouples the effect of solution ionic strength on the thickness of the DNA layer.

  7. X-ray crystal structure and small-angle X-ray scattering of sheep liver sorbitol dehydrogenase

    Energy Technology Data Exchange (ETDEWEB)

    Yennawar, Hemant [Pennsylvania State University, 8 Althouse Laboratory, University Park, PA 16802 (United States); Møller, Magda [Cornell High Energy Synchrotron Source, Ithaca, NY 14853 (United States); University of Copenhagen, DK-2100 Copenhagen (Denmark); Gillilan, Richard [Cornell High Energy Synchrotron Source, Ithaca, NY 14853 (United States); Yennawar, Neela, E-mail: nhy1@psu.edu [Pennsylvania State University, 8 Althouse Laboratory, University Park, PA 16802 (United States)

    2011-05-01

    The X-ray crystal structure and a small-angle X-ray scattering solution structure of sheep liver sorbitol dehydrogenase have been determined. The details of the interactions that enable the tetramer scaffold to be the functional biological unit have been analyzed. The X-ray crystal structure of sheep liver sorbitol dehydrogenase (slSDH) has been determined using the crystal structure of human sorbitol dehydrogenase (hSDH) as a molecular-replacement model. slSDH crystallized in space group I222 with one monomer in the asymmetric unit. A conserved tetramer that superposes well with that seen in hSDH (despite belonging to a different space group) and obeying the 222 crystal symmetry is seen in slSDH. An acetate molecule is bound in the active site, coordinating to the active-site zinc through a water molecule. Glycerol, a substrate of slSDH, also occupies the substrate-binding pocket together with the acetate designed by nature to fit large polyol substrates. The substrate-binding pocket is seen to be in close proximity to the tetramer interface, which explains the need for the structural integrity of the tetramer for enzyme activity. Small-angle X-ray scattering was also used to identify the quaternary structure of the tetramer of slSDH in solution.

  8. Determination of hydrodynamic properties of biopolymers from small-angle X-ray scattering data

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, J.J.; Damaschun, H.; Damaschun, G.; Gast, K.; Plietz, P.; Zirwer, D. (Akademie der Wissenschaften der DDR, Berlin. Zentralinstitut fuer Molekularbiologie)

    1984-10-17

    Sedimentation coefficients and translational diffusion coefficients can be determined semi-empirically from small angle X-ray scattering data. In general, the deviations of these coefficients from the experimental ones are less than 10% for proteins and small anisometrical RNA molecules within the range of molar masses from 1.7 x 10/sup 4/ to 3.5 x 10/sup 5/ g mol/sup -1/. The method can be used, furthermore, to test the consistency of experimental hydrodynamic and X-ray scattering data.

  9. Small-Angle X-Ray Scattering Study on Nanostructures of Polyimide Films

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-Xu; YIN Jing-Hua; SUN Dao-Bin; BU Wen-Bin; CHENG Wei-Dong; WU Zhong-Hua

    2010-01-01

    @@ Inorganic nanohybrid polyimide(PI)is widely applied in electrical and electronic devices for its outstanding insulating properties.Samples 100CR and 100NH are made in Dupont.Among them,100NH is a kind of pure PI films; however,100CR is a kind of inorganic nanohybrid PI/films with excellent corona-resistance.The nanostructure of PI films is investigated with small-angle x-ray scattering technique and transmission electron microscopy(TEM).

  10. Hybrid - block copolymer nanocomposites. characterization of nanostructure by small-angle X-ray scattering (SAXS)

    OpenAIRE

    A. Romo-Uribe

    2007-01-01

    The nanoscopic order of a series of block copolymer-inorganic nanocomposites was characterized using small-angle X-ray scattering (SAXS). The nanostructures were obtained via a diblock copolymer directed sol-gel synthesis. The copolymer consists of blocks of poly(isoprene) -PI- and blocks of poly(ethylene oxide) -PEO. The inorganic material consists of a crosslinked sol of 3-glycidoxypropyltrimethoxysilane and aluminum-tri-sec-butoxide in a 4:1 mole ratio, to generate an aluminosilicate ceram...

  11. Database for rapid protein classification based on small-angle X-ray scattering data

    International Nuclear Information System (INIS)

    A method was developed for rapid protein classification based on comparison of the experimental small-angle X-ray scattering data with scattering curves calculated for proteins with known structures. For this purpose, a database was compiled from about 1500 theoretical scattering curves for proteins with known structures. The potential of this method was illustrated by its application to analysis of the experimental scattering data from sperm whale myoglobin

  12. Location of two antioxidants in oriented model membranes. Small-angle x-ray diffraction study.

    OpenAIRE

    Katsaras, J.; Stinson, R H; Davis, J H; Kendall, E J

    1991-01-01

    Small-angle x-ray diffraction has been applied in locating either butylated hydroxytoluene (BHT) or delta-tocopherol and their brominated analogues at a concentration of 40 mol% in oriented bilayers of dipalmitoylphosphatidylcholine (DPPC) or DPPC + 15 mol% cholesterol at 20 degrees C. Phases were determined using swelling experiments with structure factors plotted in reciprocal space, creating a relatively smooth curve as the amount of water between the bilayers was changed. Continuous Fouri...

  13. Upgrade of the small angle X-ray scattering beamlines at the Photon Factory

    International Nuclear Information System (INIS)

    BL-10C and BL-15A at the Photon Factory, which became operational in 1982, are some of the oldest small angle X-ray scattering beamlines in the world. Recently, both beamlines were upgraded for two-dimensional (2D) SAXS-WAXS experiments. A wide-area imaging plate (IP) detector and a fast-readout flat panel (FP) detector were installed at BL-10C and BL-15A, respectively. Preliminary experiments of both systems showed promising results.

  14. X-ray crystal structure and small-angle X-ray scattering of sheep liver sorbitol dehydrogenase

    DEFF Research Database (Denmark)

    Yennawar, Hemant; Møller, Magda; Gillilan, Richard;

    2011-01-01

    The X-ray crystal structure of sheep liver sorbitol dehydrogenase (slSDH) has been determined using the crystal structure of human sorbitol dehydrogenase (hSDH) as a molecular-replacement model. slSDH crystallized in space group I222 with one monomer in the asymmetric unit. A conserved tetramer...... the substrate-binding pocket together with the acetate designed by nature to fit large polyol substrates. The substrate-binding pocket is seen to be in close proximity to the tetramer interface, which explains the need for the structural integrity of the tetramer for enzyme activity. Small-angle X...

  15. X-ray imaging based on small-angle X-ray scattering using spatial coherence of parametric X-ray radiation

    International Nuclear Information System (INIS)

    X-ray imaging based on small-angle X-ray scattering (SAXS) was carried out using the parametric X-ray radiation (PXR) source at the Laboratory for Electron Beam Research and Application (LEBRA) of Nihon University. The experimental setup employed in this novel imaging approach is the same as that employed in diffraction-enhanced imaging (DEI), a kind of X-ray phase-contrast imaging method. In SAXS-based imaging, the image contrast is correlated with the broadening of the rocking curve peak due to the scattering from micron- or sub-micron-sized grains in the sample material. An experiment using the 25.5-keV PXR beam demonstrated that SAXS-based imaging with PXR provides a substantially strong contrast for granular materials despite the extremely low density of the material.

  16. Energy-dispersive small-angle X-ray scattering with cone collimation using X-ray capillary optics

    Science.gov (United States)

    Li, Fangzuo; Liu, Zhiguo; Sun, Tianxi

    2016-09-01

    Energy-dispersive small-angle X-ray scattering (ED-SAXS) with an innovative design of cone collimation based on an ellipsoidal single-bounce capillary (ESBC) and a polycapillary parallel X-ray lens (PPXRL) had been explored. Using this new cone collimation system, scattering angle 2θ has a theoretical minimum angle related to the mean half-opening angle of the hollow cone beam of 1.42 mrad, and with the usable X-ray energy ranging from 4 to 30 keV, the resulting observable scattering vector q is down to a minimum value of about 0.003 Å-1 (or a Bragg spacing of about 2100 Å). However, the absorption of lower energies by X-ray capillary optics, sample transmission, and detector response function limits the application range to lower energy. Cone collimation ED-SAXS experiments carried out on pure water, Lupolen, and in situ temperature-dependent measurement of diacetylenic acid/melamine micelle solid were presented at three different scattering angles 2θ of 0.18°, 0.70° and 1.18° to illustrate the new opportunities offered by this technique as well as its limitations. Also, a comparison has been made by replacing the PPXRL with a pinhole, and the result shows that cone collimation ED-SAXS based on ESBC with PPXRL was helpful in improving the signal-to-noise ratio (i.e., reducing the parasitic background scattering) than ESBC with a pinhole. The cone collimation instrument based on X-ray capillary optics could be considered as a promising tool to perform SAXS experiments, especially cone collimation ED-SAXS has potential application for the in situ temperature-dependent studying on the kinetics of phase transitions.

  17. 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.

  18. Small-angle x-ray scattering measurements of hydrogen evolution from an epitaxial Nb film

    International Nuclear Information System (INIS)

    Small-angle x-ray scattering (SAXS) measurements have been performed to investigate particle morphology during in situ hydrogen evolution from a 1000-A epitaxial Nb film on (112-bar0) sapphire initially loaded to saturation with hydrogen. The SAXS intensity follows the plate or disk single-particle form factor (Q-2, where Q is the wave-vector transfer) during hydrogen evolution. A fit to this power-law behavior yields a plate thickness of ≅7 A. A second power-law behavior (Q-3) was observed after complete hydrogen evolution. This power law corresponds to the small-angle scattering response from edge dislocations and is consistent with the broadening of the lattice mosaic induced by hydride decomposition

  19. Integrative structural modeling with small angle X-ray scattering profiles

    Directory of Open Access Journals (Sweden)

    Schneidman-Duhovny Dina

    2012-07-01

    Full Text Available Abstract Recent technological advances enabled high-throughput collection of Small Angle X-ray Scattering (SAXS profiles of biological macromolecules. Thus, computational methods for integrating SAXS profiles into structural modeling are needed more than ever. Here, we review specifically the use of SAXS profiles for the structural modeling of proteins, nucleic acids, and their complexes. First, the approaches for computing theoretical SAXS profiles from structures are presented. Second, computational methods for predicting protein structures, dynamics of proteins in solution, and assembly structures are covered. Third, we discuss the use of SAXS profiles in integrative structure modeling approaches that depend simultaneously on several data types.

  20. Small angle X-ray and neutron scattering on cadmium sulfide nanoparticles in silicate glass

    Science.gov (United States)

    Kuznetsova, Yu. V.; Rempel, A. A.; Meyer, M.; Pipich, V.; Gerth, S.; Magerl, A.

    2016-08-01

    Small angle X-ray and neutron scattering on Cd and S doped glass annealed at 600 °C shows after the first 12 h nucleation and growth of spherical CdS nanoparticles with a radius of up to 34±4 Å. After the nucleation is completed after 24 h, further growth in this amorphous environment is governed by oriented particle attachment mechanism as found for a liquid medium. Towards 48 h the particle shape has changed into spheroidal with short and long axis of 40±2 Å and 120±2 Å, respectively.

  1. Small-angle scattering studies of meso-scopic structures with synchrotron X-rays

    Science.gov (United States)

    Dore, J. C.; North, A. N.; Rigden, J. S.

    1995-03-01

    The use of small-angle X-ray scattering techniques for the study of spatial inhomogeneities over the range 20 Å to 2 μm is reviewed. The basic formalism for scattering by an inhomogeneous medium is developed with particular reference to liquid suspensions, porous solids and solid aggregates. The instrumentation available on the Synchrotron Radiation Source at the Daresbury Laboratory is briefly presented and the use of the Bonse-Hart method for studies at ultra-low scattering angles described. The extraction of structural information for a range of natural and synthetic materials is presented with particular reference to microemulsions, porous silicas, clays and composites. The complementarity of X-ray and neutron techniques is critically reviewed and prospects for future developments, particularly for the study of anisotropic systems, are discussed.

  2. ORNL 10-m small-angle X-ray scattering camera

    International Nuclear Information System (INIS)

    A new small-angle x-ray scattering camera utilizing a rotating anode x-ray source, crystal monochromatization of the incident beam, pinhole collimation, and a two-dimensional position-sensitive proportional counter was developed. The sample, and the resolution element of the detector are each approximately 1 x 1 mm2, the camera was designed so that the focal spot-to-sample and sample-to-detector distances may each be varied in 0.5-m increments up to 5 m to provide a system resolution in the range 0.5 to 4.0 mrad. A large, general-purpose specimen chamber has been provided into which a wide variety of special-purpose specimen holders can be mounted. The detector has an active area of 200 x 200 mm and has up to 200 x 200 resolution elements. The data are recorded in the memory of a minicomputer by a high-speed interface which uses a microprocessor to map the position of an incident photon into an absolute minicomputer memory address. The data recorded in the computer memory can be processed on-line by a variety of programs designed to enhance the user's interaction with the experiment. At the highest angular resolution (0.4 mrad), the flux incident on the specimen is 1.0 x 106 photons/s with the x-ray source operating at 45 kV and 100 mA. SAX and its associated programs OVF and MOT are high-priority, pre-queued, nonresident foreground tasks which run under the ModComp II MAX III operating system to provide complete user control of the ORNL 10-m small-angle x-ray scattering camera

  3. Light-Induced Structural Flexibility of Thylakoid Membranes - Investigated using Small-Angle X-ray and Neutron Scattering

    OpenAIRE

    Aagaard, Thomas Helverskov

    2005-01-01

    Using small-angle x-ray and neutron scattering the light-induced structural changes in pea thylakoids have been investigated. It is shown that light-induced shinkage in the thylakoids is connected to photosynthetic electron transduction.

  4. A small-angle x-ray scattering system with a vertical layout.

    Science.gov (United States)

    Wang, Zhen; Chen, Xiaowei; Meng, Lingpu; Cui, Kunpeng; Wu, Lihui; Li, Liangbin

    2014-12-01

    A small-angle x-ray scattering (SAXS) system with a vertical layout (V-SAXS) has been designed and constructed for in situ detection on nanostructures, which is well suitable for in situ study on self-assembly of nanoparticles at liquid interface and polymer processing. A steel-tower frame on a reinforced basement is built as the supporting skeleton for scattering beam path and detector platform, ensuring the system a high working stability and a high operating accuracy. A micro-focus x-ray source combining parabolic three-dimensional multi-layer mirror and scatteringless collimation system provides a highly parallel beam, which allows us to detect the very small angle range. With a sample-to-detector distance of 7 m, the largest measurable length scale is 420 nm in real space. With a large sample zone, it is possible to install different experimental setups such as film stretching machine, which makes the system perfect to follow the microstructures evolution of materials during processing. The capability of the V-SAXS on in situ study is tested with a drying experiment of a free latex droplet, which confirms our initial design.

  5. A Microbeam Small-Angle X-ray Scattering Study on Enamel Crystallites in Subsurface Lesion

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, N; Ohta, N; Matsuo, T [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Tanaka, T; Terada, Y; Kamasaka, H; Kometani, T, E-mail: yagi@spring8.or.j [Ezaki Glico Co. Ltd., 4-6-5 Utajima, Nishiyodogawa-ku, Osaka 555-8502 (Japan)

    2010-10-01

    The early caries lesion in bovine tooth enamel was studied by two different X-ray diffraction systems at the SPring-8 third generation synchrotron radiation facility. Both allowed us simultaneous measurement of the small and large angle regions. The beam size was 6{mu}m at BL40XU and 50{mu}m at BL45XU. The small-angle scattering from voids in the hydroxyapatite crystallites and the wide-angle diffraction from the hydroxyapatite crystals were observed simultaneously. At BL40XU an X-ray image intensifier was used for the small-angle and a CMOS flatpanel detector for the large-angle region. At BL45XU, a large-area CCD detector was used to cover both regions. A linear microbeam scan at BL40XU showed a detailed distribution of voids and crystals and made it possible to examine the structural details in the lesion. The two-dimensional scan at BL45XU showed distribution of voids and crystals in a wider region in the enamel. The simultaneous small- and wide-angle measurement with a microbeam is a powerful tool to elucidate the mechanisms of demineralization and remineralization in the early caries lesion.

  6. X-ray lithography and small-angle X-ray scattering: a combination of techniques merging biology and materials science.

    Science.gov (United States)

    Marmiroli, B; Amenitsch, H

    2012-10-01

    The advent of micro/nanotechnology has blurred the border between biology and materials science. Miniaturization of chemical and biological assays, performed by use of micro/nanofluidics, requires both careful selection of the methods of fabrication and the development of materials designed for specific applications. This, in turn, increases the need for interdisciplinary combination of suitable microfabrication and characterisation techniques. In this review, the advantages of combining X-ray lithography, as fabrication technique, with small-angle X-ray scattering measurements will be discussed. X-ray lithography enables the limitations of small-angle X-ray scattering, specifically time resolution and sample environment, to be overcome. Small-angle X-ray scattering, on the other hand, enables investigation and, consequently, adjustment of the nanostructural morphology of microstructures and materials fabricated by X-ray lithography. Moreover, the effect of X-ray irradiation on novel materials can be determined by use of small-angle X-ray scattering. The combination of top-down and bottom-up methods to develop new functional materials and structures with potential in biology will be reported.

  7. The accurate assessment of small-angle X-ray scattering data

    Energy Technology Data Exchange (ETDEWEB)

    Grant, Thomas D. [Hauptman–Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203 (United States); Luft, Joseph R. [Hauptman–Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203 (United States); SUNY Buffalo, 700 Ellicott Street, Buffalo, NY 14203 (United States); Carter, Lester G.; Matsui, Tsutomu; Weiss, Thomas M.; Martel, Anne [Stanford Synchrotron Radiation Lightsource, 2575 Sand Hill Road, MS69, Menlo Park, CA 94025 (United States); Snell, Edward H., E-mail: esnell@hwi.buffalo.edu [Hauptman–Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203 (United States); SUNY Buffalo, 700 Ellicott Street, Buffalo, NY 14203 (United States)

    2015-01-01

    A set of quantitative techniques is suggested for assessing SAXS data quality. These are applied in the form of a script, SAXStats, to a test set of 27 proteins, showing that these techniques are more sensitive than manual assessment of data quality. Small-angle X-ray scattering (SAXS) has grown in popularity in recent times with the advent of bright synchrotron X-ray sources, powerful computational resources and algorithms enabling the calculation of increasingly complex models. However, the lack of standardized data-quality metrics presents difficulties for the growing user community in accurately assessing the quality of experimental SAXS data. Here, a series of metrics to quantitatively describe SAXS data in an objective manner using statistical evaluations are defined. These metrics are applied to identify the effects of radiation damage, concentration dependence and interparticle interactions on SAXS data from a set of 27 previously described targets for which high-resolution structures have been determined via X-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. The studies show that these metrics are sufficient to characterize SAXS data quality on a small sample set with statistical rigor and sensitivity similar to or better than manual analysis. The development of data-quality analysis strategies such as these initial efforts is needed to enable the accurate and unbiased assessment of SAXS data quality.

  8. Synchrotron Small-Angle X-ray Scattering Study of Cross-Linked Polymeric Micelles.

    Science.gov (United States)

    Kim, Hyun-Chul; Jin, Kyeong Sik; Lee, Se Guen; Kim, Eunjoo; Lee, Sung Jun; Jeong, Sang Won; Lee, Seung Woo; Kim, Kwang-Woo

    2016-06-01

    Polymeric micelles of methoxypoly(ethylene glycol)-b-poly(lactide) containing lysine units (mPEG-PLA-Lys4) were cross-linked by reacting of lysine moieties with a bifunctional bis(N-hydroxy-succinimide ester). The micelles were characterized in aqueous solution using dynamic light scattering, transmission electron microscopy, and synchrotron small-angle X-ray scattering. The mPEG-PLA-Lys4 was synthesized through the ring-opening polymerization of N6-carbobenzyloxy-L-lysine N-carboxyanhydride with amine-terminated mPEG-PLA and subsequent deprotection. The polymeric micelles showed enhanced micelle stability after cross-linking, which was confirmed by adding sodium dodecyl sulfate as a destabilizing agent. The average diameters measured via dynamic light scattering were 19.1 nm and 29.2 nm for non-cross-linked polymeric micelles (NCPMs) and cross-linked polymeric micelles (CPMs), respectively. The transmission electron microscopy images showed that the size of the polymeric micelles increased slightly due to cross-linking, which was in good agreement with the DLS measurements. The overall structures and internal structural changes of NCPMs and CPMs in aqueous solution were studied in detail using synchrotron X-ray scattering method. According to the structural parameters of X-ray scattering analysis, CPMs with a more densely packed core structure were formed by reacting bifunctional cross-linking agents with lysine amino groups located in the innermost core of the polymeric micelles. PMID:27427731

  9. The accurate assessment of small-angle X-ray scattering data

    International Nuclear Information System (INIS)

    A set of quantitative techniques is suggested for assessing SAXS data quality. These are applied in the form of a script, SAXStats, to a test set of 27 proteins, showing that these techniques are more sensitive than manual assessment of data quality. Small-angle X-ray scattering (SAXS) has grown in popularity in recent times with the advent of bright synchrotron X-ray sources, powerful computational resources and algorithms enabling the calculation of increasingly complex models. However, the lack of standardized data-quality metrics presents difficulties for the growing user community in accurately assessing the quality of experimental SAXS data. Here, a series of metrics to quantitatively describe SAXS data in an objective manner using statistical evaluations are defined. These metrics are applied to identify the effects of radiation damage, concentration dependence and interparticle interactions on SAXS data from a set of 27 previously described targets for which high-resolution structures have been determined via X-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. The studies show that these metrics are sufficient to characterize SAXS data quality on a small sample set with statistical rigor and sensitivity similar to or better than manual analysis. The development of data-quality analysis strategies such as these initial efforts is needed to enable the accurate and unbiased assessment of SAXS data quality

  10. Optical and Geometric Properties of Free Silica Nanoparticles Studied by Small-Angle X-Ray Scattering

    Science.gov (United States)

    Langer, Burkhard; Raschpichler, Christopher; Gruner, Mathias; Antonsson, Egill; Goroncy, Christian; Graf, Christina; Rühl, Eckart

    2016-09-01

    Elastic small-angle X-ray scattering (SAXS) of free silica (SiO2) nanoparticles is reported (d = 100-180 nm). The particles were prepared by a modified Stöber synthesis in narrow size distributions with controlled surface roughness and functionalization. Angle-resolved small-angle X-ray scattering patterns are shown to be sensitive to these changes in particle properties. It is reported that there is an exponential decrease in scattered X-ray intensity towards larger scattering angles as well as distinct oscillations, which is fully explained by Mie theory. Small-angle X-ray scattering of mesoporous nanoparticles with rough surfaces is compared to that of microporous nanoparticles with smooth surfaces, revealing distinct differences that are rationalized by diffuse scattering from nanoparticle pores in addition to the dominating contribution of Mie scattering. Furthermore, results from small-angle X-ray scattering experiments on functionalized silica nanoparticles are presented, where the incorporation of the dye fluorescein isothiocyanate is found to cause changes in the optical properties of the nanoparticles, as compared to non-functionalized samples. Small, but distinct deviations in particle size derived from electron microscopy and from small-angle X-ray scattering are observed. These are rationalized by particle shrinking occurring in electron microscopy as well as slight changes in optical properties of the nanoparticle samples.

  11. Structure Factor of Dimyristoylphosphatidylcholine Unilamellar Vesicles Small-Angle X-Ray Scattering Study

    CERN Document Server

    Kiselev, M A; Kisselev, A M; Lesieur, P; Aksenov, V L

    2003-01-01

    Small-angle X-ray scattering (SAXS) experiments have been performed on dimyristoylphosphatidylcholine (DMPC) unilamellar vesicles in 40 % aqueous sucrose solution. Model of separated form factors was applied for the evaluation of SAXS curves from large unilamellar vesicles. For the first time vesicle structure factor, polydispersity, average radius and membrane thickness were calculated simultaneously from the SAXS curves at T=306{\\circ}C for DMPC concentrations in the range from 15 to 75 mM (1-5 % w/w). Structure factor correction to the scattering curve was shown to be negligibly small for the lipid concentration of 15 mM (1 % w/w). It was proved to be necessary to introduce structure factor correction to the scattering curves for lipid concentrations {\\ge}30 mM (2 % w/w).

  12. Characterization of Nanocomposite filler Morphology using Ultra Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Justice, Ryan S.; Schaefer, Dale W. (UCIN); (AFRL)

    2010-10-22

    Loading polymer matrices with nanoscale fillers is widely believed to have the potential to push polymer properties to extreme values. Realization of anticipated properties, however, has proven elusive. Recent nanocomposite research suggests better characterization of the large-scale morphology will provide insight explaining these shortfalls. This work will present ultra-small angle X-ray scattering as a viable tool for elucidating the hierarchical filler morphology that exists within polymer nanocomposites. Scattering analysis tools developed by our group will be applied to scattering data from nanocomposites filled with carbon nanotubes, layered silicates, and colloidal silica. The relationship between imaging data and scattering data will be discussed in the context of filler dispersion. Finally, the impact of large-scale filler morphology on mechanical and electrical properties will be discussed.

  13. Small angle x-ray scattering and electron microscopy of nanoparticles formed in an electrical arc

    Directory of Open Access Journals (Sweden)

    E. Carvou

    2013-03-01

    Full Text Available Small Angle X-ray Scattering has been used to characterize nanoparticles generated by electrical arcing between metallic (AgSnO2 electrodes. The particles are found to have diameters between 30 and 40 nm and display smooth surfaces suggesting that they are either in liquid form or have solidified from the liquid state. Particles collected around the electrodes were analyzed by Transmission Electron Microscopy and were seen to be much larger than those seen in the SAXS measurement, to be spherical in form and composed of silver metal with irregular tin oxide particles deposited on their surface. Mixed metal nanoparticles can have important practical applications and the use of mixed sintered electrodes may be a direct method for their production.

  14. Robust, high-throughput solution structural analyses by small angle X-ray scattering (SAXS)

    Energy Technology Data Exchange (ETDEWEB)

    Hura, Greg L.; Menon, Angeli L.; Hammel, Michal; Rambo, Robert P.; Poole II, Farris L.; Tsutakawa, Susan E.; Jenney Jr, Francis E.; Classen, Scott; Frankel, Kenneth A.; Hopkins, Robert C.; Yang, Sungjae; Scott, Joseph W.; Dillard, Bret D.; Adams, Michael W. W.; Tainer, John A.

    2009-07-20

    We present an efficient pipeline enabling high-throughput analysis of protein structure in solution with small angle X-ray scattering (SAXS). Our SAXS pipeline combines automated sample handling of microliter volumes, temperature and anaerobic control, rapid data collection and data analysis, and couples structural analysis with automated archiving. We subjected 50 representative proteins, mostly from Pyrococcus furiosus, to this pipeline and found that 30 were multimeric structures in solution. SAXS analysis allowed us to distinguish aggregated and unfolded proteins, define global structural parameters and oligomeric states for most samples, identify shapes and similar structures for 25 unknown structures, and determine envelopes for 41 proteins. We believe that high-throughput SAXS is an enabling technology that may change the way that structural genomics research is done.

  15. Small-angle neutron and X-ray scattering reveal conformational changes in rhodopsin activation

    Science.gov (United States)

    Shrestha, Utsab R.; Bhowmik, Debsindhu; Perera, Suchitrhanga M. C. D.; Chawla, Udeep; Struts, Andrey V.; Graziono, Vito; Pingali, Sai Venkatesh; Heller, William T.; Qian, Shuo; Brown, Michael F.; Chu, Xiang-Qiang

    2015-03-01

    Understanding G-protein-coupled receptor (GPCR) activation plays a crucial role in the development of novel improved molecular drugs. During photo-activation, the retinal chromophore of the visual GPCR rhodopsin isomerizes from 11-cis to all-trans conformation, yielding an equilibrium between inactive Meta-I and active Meta-II states. The principal goals of this work are to address whether the activation of rhodopsin leads to a single state or a conformational ensemble, and how protein organizational structure changes with detergent environment in solution. We use both small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) techniques to answer the above questions. For the first time we observe the change in protein conformational ensemble upon photo-activation by SANS with contrast variation, which enables the separate study of the protein structure within the detergent assembly. In addition, SAXS study of protein structure within detergent assembly suggests that the detergent molecules form a belt of monolayer (micelle) around protein with different geometrical shapes to keep the protein in folded state.

  16. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kao-Hsiang, E-mail: codeliu@gmail.com [Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan (China); Joint Institute for Neutron Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Zhang, Yang [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Jeng, U-Ser [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Mou, Chung-Yuan [Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan (China)

    2015-09-07

    Water’s behavior near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. By monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed that the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (α{sub p}) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. In addition, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated α{sub p} peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface.

  17. Particle-scale structure in frozen colloidal suspensions from small-angle x-ray scattering

    KAUST Repository

    Spannuth, Melissa

    2011-02-01

    During directional solidification of the solvent in a colloidal suspension, the colloidal particles segregate from the growing solid, forming high-particle-density regions with structure on a hierarchy of length scales ranging from that of the particle-scale packing to the large-scale spacing between these regions. Previous work has concentrated mostly on the medium- to large-length scale structure, as it is the most accessible and thought to be more technologically relevant. However, the packing of the colloids at the particle scale is an important component not only in theoretical descriptions of the segregation process, but also to the utility of freeze-cast materials for new applications. Here we present the results of experiments in which we investigated this structure across a wide range of length scales using a combination of small-angle x-ray scattering and direct optical imaging. As expected, during freezing the particles were concentrated into regions between ice dendrites forming a microscopic pattern of high- and low-particle-density regions. X-ray scattering indicates that the particles in the high-density regions were so closely packed as to be touching. However, the arrangement of the particles does not conform to that predicted by standard interparticle pair potentials, suggesting that the particle packing induced by freezing differs from that formed during equilibrium densification processes. © 2011 American Physical Society.

  18. Discovering New Features of Protein Complexes Structures by Small-Angle X-Ray Scattering

    Science.gov (United States)

    Oliveira, C. L. P.; Vorup-Jensen, T.; Andersen, C. B. F.; Andersen, G. R.; Pedersen, J. S.

    In spite of the recent advances in the X-Ray crystallography and nuclear magnetic resonance techniques, the determination of the quaternary structure of large protein complexes is still a challenge in molecular biology and biological sciences. In this respect, small-angle X-ray scattering (SAXS) is a key technique, enabling the determination of the possible structural conformation of complexes in an almost native state. Despite of this book being devoted to scattering techniques by synchrotron radiation, in this chapter we present two examples of application of laboratory-based SAXS to protein solution. The fundaments of the technique are obviously the same and have been deeply described in Chap. 2. In this chapter, we will introduce the application of SAXS to protein solution. Special emphasis is done on data reduction and absolute units calibration. As an example to illustrate the power of this technique, two new data sets for two protein complexes will be presented. This will show how high-quality SAXS data combined with advanced model strategies enables the determination of the quaternary structure of protein complexes.

  19. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering.

    Science.gov (United States)

    Liu, Kao-Hsiang; Zhang, Yang; Jeng, U-Ser; Mou, Chung-Yuan

    2015-09-01

    Water's behavior near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. By monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed that the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (αp) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. In addition, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated αp peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface. PMID:26342380

  20. Small-angle x-ray scattering study on the structure of microcrystalline and nanofibrillated cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Leppaenen, Kirsi; Pirkkalainen, Kari; Penttilae, Paavo; Serimaa, Ritva [Division of Materials Physics, Department of Physics, P.O.B. 64, FI-00014 University of Helsinki (Finland); Sievaenen, Jenni [VTT, Espoo (Finland); Kotelnikova, Nina, E-mail: kirsi.leppanen@helsinki.f [Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoy pr. 31, St. Petersburg 199004 (Russian Federation)

    2010-10-01

    The effects of different solvents on the structure of microcrystalline and nanofibrillated cellulose (MCC, NFC) were studied using small-angle x-ray scattering (SAXS). MCC was immersed in water, ethanol, and acetone, and NFC was immersed only in water and ethanol, but studied also in the form of foam-like water-NFC-gel in wet, air-dried and re-wet states. The solvent affected the average chord length, which reveals the typical length scale of the structure of the sample: 2.4 {+-} 0.1 nm was obtained for MCC-water, 2.5 {+-} 0.1 nm for re-wet NFC-gel, 1.6 {+-} 0.1 nm for MCC-ethanol, 1.2 {+-} 0.1 nm for NFC-ethanol, and 1.3 {+-} 0.1 nm for MCC-acetone. The specific surface of cellulose increased strongly when MCC and NFC were immersed in the solvents compared to dry cellulose. The specific surface of cellulose was determined to be larger for NFC-water than MCC-water, and slightly larger for dry NFC powder than for dry MCC, which can be explained by the fact that the width of cellulose crystallites perpendicular to the cellulose chain direction was slightly larger in MCC than in NFC on the basis of wide-angle x-ray scattering results.

  1. Application of small angle X-ray scattering synchrotron technology for measuring ovine meat quality.

    Science.gov (United States)

    Hoban, J M; Hopkins, D L; Kirby, N; Collins, D; Dunshea, F R; Kerr, M G; Bailes, K; Cottrell, J J; Holman, B W B; Brown, W; Ponnampalam, E N

    2016-07-01

    A small angle X-ray scattering (SAXS) synchrotron was used to evaluate 100 ovine m. longissimus lumborum, representing lamb (n=50) and sheep (n=50). The diffraction of X-rays gives information on muscle myofibril structure and fat content. The linear relationships between SAXS measures with measures such as, shear force, intramuscular fat content (IMF) and collagen content/solubility, were investigated. A relationship was found between the d-spacing of the actin/myosin fibril spacing (SAX1 and SAX2) and the cross sectional area of the rhombohedral unit cell (Cell area) and shear force after 1 and 5day ageing. There was a positive relationship between IMF and a SAXS Fat area measure. There was a muscle site effect on SAX1, SAX2 and Cell area, with the cranial site having a larger distance between myofibrils. The potential of SAXS as a powerful research tool to determine not only the structural components of ovine tenderness, but also the fat content related to IMF is evident. PMID:26971308

  2. Effect of Cobalt Fillers on Polyurethane Segmentations Investigated by Synchrotron Small Angle X-Ray Scattering

    Directory of Open Access Journals (Sweden)

    Krit Koyvanich

    2013-01-01

    Full Text Available The segmentation between rigid and rubbery chains in polyurethanes (PUs influences polymeric properties and implementations. Several models have successfully been proposed to visualize the configuration between the hard segment (HS and soft segment (SS. For particulate PU composites, the arrangement of HS and SS is more complicated because the fillers tend to disrupt the chain formation and segmentation. In this work, the effect of ferromagnetic cobalt (Co powders (average diameter 2 μm on PU synthesized from a reaction between polyether polyol (soft segment and diphenylmethane-4,4′-diisocyanate (hard segment was studied with varying loadings (0, 20, 40, and 60 wt.%. The 300 μm thick PU/Co samples were tape-casted and then received heat treatment at 80°C for 180 min. From synchrotron small angle X-ray scattering (SAXS, the plot of the X-ray scattering intensity (I against the scattering vector (q exhibited a typical single peak of PU whose intensity was reduced by the increase in the Co loading. Characteristic SAXS peaks in the case of 0-20 wt.% Co agreed well with the scattering by globular hard segment domains according to Zernike-Prins and Percus-Yevick models. The higher Co loadings led to larger deviations from all theoretical models.

  3. Alzheimer's disease imaging biomarkers using small-angle x-ray scattering

    Science.gov (United States)

    Choi, Mina; Alam, Nadia; Dahal, Eshan; Ghammraoui, Bahaa; Badano, Aldo

    2016-03-01

    There is a need for novel imaging techniques for the earlier detection of Alzheimer's disease (AD). Two hallmarks of AD are amyloid beta (Aβ) plaques and tau tangles that are formed in the brain. Well-characterized x-ray cross sections of Aβ and tau proteins in a variety of structural states could potentially be used as AD biomarkers for small-angle x-ray scattering (SAXS) imaging without the need for injectable probes or contrast agents. First, however, the protein structures must be controlled and measured to determine accurate biomarkers for SAXS imaging. Here we report SAXS measurements of Aβ42 and tau352 in a 50% dimethyl sulfoxide (DMSO) solution in which these proteins are believed to remain monomeric because of the stabilizing interaction of DMSO solution. Our SAXS analysis showed the aggregation of both proteins. In particular, we found that the aggregation of Aβ42 slowly progresses with time in comparison to tau352 that aggregates at a faster rate and reaches a steady-state. Furthermore, the measured signals were compared to the theoretical SAXS profiles of Aβ42 monomer, Aβ42 fibril, and tau352 that were computed from their respective protein data bank structures. We have begun the work to systematically control the structural states of these proteins in vitro using various solvent conditions. Our future work is to utilize the distinct SAXS profiles of various structural states of Aβ and tau to build a library of signals of interest for SAXS imaging in brain tissue.

  4. A triple axis double crystal multiple reflection camera for ultra small angle X-ray scattering

    Science.gov (United States)

    Lambard, Jacques; Lesieur, Pierre; Zemb, Thomas

    1992-06-01

    To extend the domain of small angle X-ray scattering requires multiple reflection crystals to collimate the beam. A double crystal, triple axis X-ray camera using multiple reflection channel cut crystals is described. Procedures for measuring the desmeared scattering cross-section on absolute scale are described as well as the measurement from several typical samples : fibrils of collagen, 0.3 μm diameter silica spheres, 0.16 μm diameter interacting latex spheres, porous lignite coal, liquid crystals in a surfactant-water system, colloidal crystal of 0.32 μm diameter silica spheres. L'extension du domaine de diffusion des rayons-X vers les petits angles demande l'emploi de cristaux à réflexions multiples pour collimater le faisceau. Nous décrivons une caméra à rayons-X à trois axes où les réflexions multiples sont réalisées dans deux cristaux à gorge. Nous donnons ensuite les procédures de déconvolution pour obtenir la section efficace de diffusion en échelle absolue, ainsi que les résultats des mesures effectuées avec plusieurs échantillons typiques : fibres de collagène, sphères de silice de 0,3 μm de diamètre, sphères de latex de 0,16 μm de diamètre en interaction, charbon lignite poreux, cristaux liquides formés dans un système eau-tensioactif, solution colloïdale de sphères de silice de 0,32 μm de diamètre.

  5. Nano-scale morphology of melanosomes revealed by small-angle X-ray scattering.

    Directory of Open Access Journals (Sweden)

    Thomas Gorniak

    Full Text Available Melanosomes are highly specialized organelles that produce and store the pigment melanin, thereby fulfilling essential functions within their host organism. Besides having obvious cosmetic consequences--determining the color of skin, hair and the iris--they contribute to photochemical protection from ultraviolet radiation, as well as to vision (by defining how much light enters the eye. Though melanosomes can be beneficial for health, abnormalities in their structure can lead to adverse effects. Knowledge of their ultrastructure will be crucial to gaining insight into the mechanisms that ultimately lead to melanosome-related diseases. However, due to their small size and electron-dense content, physiologically intact melanosomes are recalcitrant to study by common imaging techniques such as light and transmission electron microscopy. In contrast, X-ray-based methodologies offer both high spatial resolution and powerful penetrating capabilities, and thus are well suited to study the ultrastructure of electron-dense organelles in their natural, hydrated form. Here, we report on the application of small-angle X-ray scattering--a method effective in determining the three-dimensional structures of biomolecules--to whole, hydrated murine melanosomes. The use of complementary information from the scattering signal of a large ensemble of suspended organelles and from single, vitrified specimens revealed a melanosomal sub-structure whose surface and bulk properties differ in two commonly used inbred strains of laboratory mice. Whereas melanosomes in C57BL/6J mice have a well-defined surface and are densely packed with 40-nm units, their counterparts in DBA/2J mice feature a rough surface, are more granular and consist of 60-nm building blocks. The fact that these strains have different coat colors and distinct susceptibilities to pigment-related eye disease suggest that these differences in size and packing are of biological significance.

  6. Scanning of Adsorption Hysteresis In Situ with Small Angle X-Ray Scattering

    Science.gov (United States)

    Mitropoulos, Athanasios Ch.; Favvas, Evangelos P.; Stefanopoulos, Konstantinos L.; Vansant, Etienne F.

    2016-01-01

    Everett’s theorem-6 of the domain theory was examined by conducting adsorption in situ with small angle x-ray scattering (SAXS) supplemented by the contrast matching technique. The study focuses on the spectrum differences of a point to which the system arrives from different scanning paths. It is noted that according to this theorem at a common point the system has similar macroscopic properties. Furthermore it was examined the memory string of the system. We concluded that opposite to theorem-6: a) at a common point the system can reach in a finite (not an infinite) number of ways, b) a correction for the thickness of the adsorbed film prior to capillary condensation is necessary, and c) the scattering curves although at high-Q values coincide, at low-Q values are different indicating different microscopic states. That is, at a common point the system holds different metastable states sustained by hysteresis effects. These metastable states are the ones which highlight the way of a system back to a return point memory (RPM). Entering the hysteresis loop from different RPMs different histories are implanted to the paths toward the common point. Although in general the memory points refer to relaxation phenomena, they also constitute a characteristic feature of capillary condensation. Analogies of the no-passing rule and the adiabaticity assumption in the frame of adsorption hysteresis are discussed. PMID:27741263

  7. Lysozyme crystal growth, as observed by small angle X-ray scattering, proceeds without crystallization intermediates

    International Nuclear Information System (INIS)

    A combination of small angle X-ray scattering and gel techniques was used to follow the kinetics of protein crystal growth as a function of time. Hen egg white lysozyme, at different protein concentrations, was used as a model system. A new sample holder was designed, in which supersaturation is induced in the presence of salt by decreasing the temperature. It had been shown previously that a decrease in temperature and/or an increase in crystallizing agent induces an increase in the attractive interactions present in the lysozyme solutions, the lysozyme remaining monomeric. In the present paper we show that similar behaviour is observed in NaCl when agarose gels are used. During crystal growth, special attention was paid to determine whether oligomers were formed as the protein in solution was incorporated in the newly formed crystals. From these first series of experiments, we did not find any indication of oligomer formation between monomer in solution and crystal. The results obtained are in agreement with the hypothesis that lysozyme crystals in NaCl grow by addition of monomeric particles. (orig.)

  8. Crystal Growth through Progressive Densification Identified by Synchrotron Small-Angle X-ray Scattering

    International Nuclear Information System (INIS)

    For the first time, evolution of the interfacial structure of aluminum hydroxide nuclei forming within concentrated caustic solutions has been examined in situ in real time. In both dilute and concentrated caustic aluminate solutions (NaOH = 1.0 and 3.0 M, respectively, (NaOH)/(Al) = 1.22), the measured synchrotron small-angle X-ray scattering data indicate distinctly different surface structures throughout the maturation process. In the dilute solution, the data are consistent with a thin layer of less dense, recently accreted material on the surface of large fully dense particles -- consistent with the familiar model process of species attachment to well-faceted surfaces. In contrast to this, the data for the concentrated solution are consistent with large diffuse particles growing with a mass fractal dimension of approximately 2.5 which densify to form rough surface fractal particles on maturation. This unusual densification crystallization mechanism may occur in analogous concentrated systems where the fractal structures may be entropically stablized.

  9. Automated acquisition and analysis of small angle X-ray scattering data

    International Nuclear Information System (INIS)

    Small Angle X-ray Scattering (SAXS) is a powerful tool in the study of biological macromolecules providing information about the shape, conformation, assembly and folding states in solution. Recent advances in robotic fluid handling make it possible to perform automated high throughput experiments including fast screening of solution conditions, measurement of structural responses to ligand binding, changes in temperature or chemical modifications. Here, an approach to full automation of SAXS data acquisition and data analysis is presented, which advances automated experiments to the level of a routine tool suitable for large scale structural studies. The approach links automated sample loading, primary data reduction and further processing, facilitating queuing of multiple samples for subsequent measurement and analysis and providing means of remote experiment control. The system was implemented and comprehensively tested in user operation at the BioSAXS beamlines X33 and P12 of EMBL at the DORIS and PETRA storage rings of DESY, Hamburg, respectively, but is also easily applicable to other SAXS stations due to its modular design.

  10. Topological investigation of electronic silicon nanoparticulate aggregates using ultra-small-angle X-ray scattering

    International Nuclear Information System (INIS)

    The network topology of two types of silicon nanoparticles, produced by high energy milling and pyrolysis of silane, in layers deposited from inks on permeable and impermeable substrates has been quantitatively characterized using ultra-small-angle X-ray scattering, supported by scanning electron microscopy observations. The milled particles with a highly polydisperse size distribution form agglomerates, which in turn cluster to form larger aggregates with a very high degree of aggregation. Smaller nanoparticles with less polydisperse size distribution synthesized by thermal catalytic pyrolysis of silane form small open clusters. The Sauter mean diameters of the primary particles of the two types of nanoparticles were obtained from USAXS particle volume to surface ratio, with values of ∼41 and ∼21 nm obtained for the high energy milled and pyrolysis samples, respectively. Assuming a log-normal distribution of the particles, the geometric standard deviation of the particles was calculated to be ∼1.48 for all the samples, using parameters derived from the unified fit to the USAXS data. The flow properties of the inks and substrate combination lead to quantitative changes in the mean particle separation, with slowly curing systems with good capillary flow resulting in denser networks with smaller aggregates and better contact between particles.

  11. Characterization of Physically and Chemically Separated Athabasca Asphaltenes Using Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Amundaraín Hurtado, Jesús Leonardo; Chodakowski, Martin; Long, Bingwen; Shaw, John M. (Alberta)

    2012-02-07

    Athabasca asphaltenes were characterized using small-angle X-ray scattering (SAXS). Two methods were used to separate asphaltenes from the Athabasca bitumen: namely, chemical separation by precipitation with n-pentane and physical separation by nanofiltration using a zirconia membrane with a 20 nm average pore size. The permeate and chemically separated samples were diluted in 1-methylnaphtalene and n-dodecane prior to SAXS measurements. The temperature and asphaltene concentration ranges were 50-310 C and 1-10.4 wt %, respectively. Model-independent analysis of SAXS data provided the radius of gyration and the scattering coefficients. Model-dependent fits provided size distributions for asphaltenes assuming that they are dense and spherical. Model-independent analysis for physically and chemically separated asphaltenes showed significant differences in nominal size and structure, and the temperature dependence of structural properties. The results challenge the merits of using chemically separated asphaltene properties as a basis for asphaltene property prediction in hydrocarbon resources. While the residuals for model-dependent fits are small, the results are inconsistent with the structural parameters obtained from model-independent analysis.

  12. Studies of protein structure in solution and protein folding using synchrotron small-angle x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lingling

    1996-04-01

    Synchrotron small angle x-ray scattering (SAXS) has been applied to the structural study of several biological systems, including the nitrogenase complex, the heat shock cognate protein (hsc70), and lysozyme folding. The structural information revealed from the SAXS experiments is complementary to information obtained by other physical and biochemical methods, and adds to our knowledge and understanding of these systems.

  13. Parallel GPGPU Evaluation of Small Angle X-ray Scattering Profiles in a Markov Chain Monte Carlo Framework

    DEFF Research Database (Denmark)

    Antonov, Lubomir Dimitrov; Andreetta, Christian; Hamelryck, Thomas Wim

    2013-01-01

    Inference of protein structure from experimental data is of crucial interest in science, medicine and biotechnology. Low-resolution methods, such as small angle X-ray scattering (SAXS), play a major role in investigating important biological questions regarding the structure of proteins in soluti...

  14. Studying nanostructure gradients in injection-molded polypropylene/montmorillonite composites by microbeam small-angle x-ray scattering

    DEFF Research Database (Denmark)

    Stribeck, Norbert; Schneider, Konrad; Zeinolebadi, Ahmad;

    2014-01-01

    The core–shell structure in oriented cylindrical rods of polypropylene (PP) and nanoclay composites (NCs) from PP and montmorillonite (MMT) is studied by microbeam small-angle x-ray scattering (SAXS). The structure of neat PP is almost homogeneous across the rod showing regular semicrystalline st...

  15. An Assessment of Critical Dimension Small Angle X-ray Scattering Metrology for Advanced Semiconductor Manufacturing

    Science.gov (United States)

    Settens, Charles M.

    Simultaneous migration of planar transistors to FinFET architectures, the introduction of a plurality of materials to ensure suitable electrical characteristics, and the establishment of reliable multiple patterning lithography schemes to pattern sub-10 nm feature sizes imposes formidable challenges to current in-line dimensional metrologies. Because the shape of a FinFET channel cross-section immediately influences the electrical characteristics, the evaluation of 3D device structures requires measurement of parameters beyond traditional critical dimension (CD), including their sidewall angles, top corner rounding and footing, roughness, recesses and undercuts at single nanometer dimensions; thus, metrologies require sub-nm and approaching atomic level measurement uncertainty. Synchrotron critical dimension small angle X-ray scattering (CD-SAXS) has unique capabilities to non-destructively monitor the cross-section shape of surface structures with single nanometer uncertainty and can perform overlay metrology to sub-nm uncertainty. In this dissertation, we perform a systematic experimental investigation using CD-SAXS metrology on a hierarchy of semiconductor 3D device architectures including, high-aspect-ratio contact holes, H 2 annealed Si fins, and a series of grating type samples at multiple points along a FinFET fabrication process increasing in structural intricacy and ending with fully fabricated FinFET. Comparative studies between CD-SAXS metrology and other relevant semiconductor dimensional metrologies, particularly CD-SEM, CD-AFM and TEM are used to determine physical limits of CD-SAXS approach for advanced semiconductor samples. CD-SAXS experimental tradeoffs, advice for model-dependent analysis and thoughts on the compatibility with a semiconductor manufacturing environment are discussed.

  16. Structural characterization of the human cerebral myelin sheath by small angle x-ray scattering

    Science.gov (United States)

    DeFelici, M.; Felici, R.; Ferrero, C.; Tartari, A.; Gambaccini, M.; Finet, S.

    2008-10-01

    Myelin is a multi-lamellar membrane surrounding neuronal axons and increasing their conduction velocity. When investigated by small-angle x-ray scattering (SAXS), the lamellar quasi-periodical arrangement of the myelin sheath gives rise to distinct peaks, which allow the determination of its molecular organization and the dimensions of its substructures. In this study we report on the myelin sheath structural determination carried out on a set of human brain tissue samples coming from surgical biopsies of two patients: a man around 60 and a woman nearly 90 years old. The samples were extracted either from white or grey cerebral matter and did not undergo any manipulation or chemical-physical treatment, which could possibly have altered their structure, except dipping them into a formalin solution for their conservation. Analysis of the scattered intensity from white matter of intact human cerebral tissue allowed the evaluation not only of the myelin sheath periodicity but also of its electronic charge density profile. In particular, the thicknesses of the cytoplasm and extracellular regions were established, as well as those of the hydrophilic polar heads and hydrophobic tails of the lipid bilayer. SAXS patterns were measured at several locations on each sample in order to establish the statistical variations of the structural parameters within a single sample and among different samples. This work demonstrates that a detailed structural analysis of the myelin sheath can also be carried out in randomly oriented samples of intact human white matter, which is of importance for studying the aetiology and evolution of the central nervous system pathologies inducing myelin degeneration.

  17. Increasing correlation length in bulk supercooled H2O, D2O, and NaCl solution determined from small angle x-ray scattering

    OpenAIRE

    Huang, Congcong; Weiss, T M; Nordlund, D.; Wikfeldt, K. T.; Pettersson, L. G. M.; Nilsson, A.

    2010-01-01

    Using small angle x-ray scattering, we find that the correlation length of bulk liquid water shows a steep increase as temperature decreases at subzero temperatures (supercooling) and that it can, similar to the thermodynamic response functions, be fitted to a power law. This indicates that the anomalous properties of water are attributable to fluctuations between low- and high-density regions with rapidly growing average size upon supercooling. The substitution of H2O with D2O, as well as th...

  18. Simultaneous measurement of X-ray small angle scattering, absorption and reactivity: A continuous flow catalysis reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sungsik; Lee, Byeongdu; Seifert, Soenke [X-ray Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Vajda, Stefan [Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Department of Chemical Engineering, Yale University, 9 Hillhouse Avenue, New Haven, CT 06520 (United States); Winans, Randall E., E-mail: rewinans@anl.gov [X-ray Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2011-09-01

    A fixed-bed, continuous flow catalysis reactor is described, in which GISAXS (grazing incidence small angle X-ray scattering)/GIXAS (grazing incidence X-ray absorption spectroscopy) and TPR (temperature-programmed reaction) can be measured simultaneously on samples with low metal coverage. The capabilities offered by this setup are illustrated in the example of the dehydrogenation of cyclohexene, where the size, oxidation state and reactivity of supported cobalt clusters were investigated under ambient pressure conditions. The GIXAS data reveal an evolution of the oxidation state of the catalytic particles with temperature. Simultaneously recorded GISAXS data show stable clusters, without any indication of sintering under employed reaction conditions.

  19. Small-angle X-ray scattering at high brilliance european synchrotrons for biotechnology and nano-technology

    Energy Technology Data Exchange (ETDEWEB)

    Svergun, D.; Malfois, M. [EMBL c/o DESY, Hamburg (Germany); Svergun, D. [Institute of Crystallography, Russian Academy of Sciences, Moscow (Russian Federation); Douka, M. [Commission Europeenne, DG III, Bruxelles (Belgium); Riekel, Ch. [European Synchrotron Radiation Facility (ESRF), 38 - Grenoble (France); Perez, J. [Soleil, 91 - Saclay (France); Roessle, M. [European Molecular Biology Laboratory (EMBL), 38 - Grenoble (France); Amenitsch, H. [IBN/Elettra (Germany); Gunter Grossman, J. [Daresbury Synchrotron Radiation Source (SRS) (United Kingdom); Vestergaard, B. [University of Pharmaceutical Sciences, Copenhagen (Denmark); Receveur-Brechot, V. [Centre National de la Recherche Scientifique (CNRS/AFMB), 13 - Marseille (France); Roth, St.V. [Deutsches Elektronen Synchrotron (HASYLAB), Hamburg (Germany); Ferrari, E. [National Institute for the Physics of Matter (CNR-INFM), Trieste (Italy)

    2007-07-01

    Different issues such as micro-fluidic devices for SAXS (small-angle X-ray diffraction), the use of electro-spray and ion trapping for SAXS in the gas phase, the study of flexible and disordered proteins through SAXS, the time-resolved SAXS studies in solution, or the study of nano-structured soft materials, were addressed in this workshop. This document gathers the transparencies of the presentations.

  20. Small angle X-ray scattering and transmission electron microscopy study of the Lactobacillus brevis S-layer protein

    Energy Technology Data Exchange (ETDEWEB)

    Jaeaeskelaeinen, Pentti [Department of Biomedical Engineering and Computational Science, PO Box 2200, FI-02015 Aalto University School of Science and Technology (Finland); Engelhardt, Peter [Haartman Institute, Department of Pathology, PO Box 21, FIN-00014 University of Helsinki (Finland); Hynoenen, Ulla; Palva, Airi [Department of Basic Veterinary Sciences, Division of Microbiology, FIN-00014 University of Helsinki (Finland); Torkkeli, Mika; Serimaa, Ritva, E-mail: ritva.serimaa@helsinki.f [Department of Physics, POB 64, 00014 University of Helsinki (Finland)

    2010-10-01

    The structure of self-assembly domain containing recombinant truncation mutants of Lactobacillus brevis surface layer protein SlpA in aqueous solution was studied using small-angle X-ray scattering and transmission electron microscopy. The proteins were found out to interact with each other forming stable globular oligomers of about 10 monomers. The maximum diameter of the oligomers varied between 75 A and 435 A.

  1. Small angle X-ray scattering and transmission electron microscopy study of the Lactobacillus brevis S-layer protein

    Science.gov (United States)

    Jääskeläinen, Pentti; Engelhardt, Peter; Hynönen, Ulla; Torkkeli, Mika; Palva, Airi; Serimaa, Ritva

    2010-10-01

    The structure of self-assembly domain containing recombinant truncation mutants of Lactobacillus brevis surface layer protein SlpA in aqueous solution was studied using small-angle X-ray scattering and transmission electron microscopy. The proteins were found out to interact with each other forming stable globular oligomers of about 10 monomers. The maximum diameter of the oligomers varied between 75 Å and 435 Å.

  2. Quantitative Analysis of the Orientation of Mineral in Bone from Small-Angle X-Ray Scattering Patterns

    Science.gov (United States)

    Matsushima, Norio; Akiyama, Morio; Terayama, Yoshio

    1982-01-01

    The small-angle X-ray scattering data from a rabbit femur is quantitatively evaluated with respect to the mineral distribution in bone. The results show the existence of a needle-like mineral with a length of at least 300 A and a preferred orientation of the needle axes parallel to the long axis of the bone. The angular distribution of the needle axes gives a value of 30° for the mean inclination.

  3. Small-angle X-ray scattering at high brilliance european synchrotrons for biotechnology and nano-technology

    International Nuclear Information System (INIS)

    Different issues such as micro-fluidic devices for SAXS (small-angle X-ray diffraction), the use of electro-spray and ion trapping for SAXS in the gas phase, the study of flexible and disordered proteins through SAXS, the time-resolved SAXS studies in solution, or the study of nano-structured soft materials, were addressed in this workshop. This document gathers the transparencies of the presentations

  4. Small angles X-ray diffraction and Mössbauer characterization of annealed Tb/Fe multilayer

    Indian Academy of Sciences (India)

    O M Lemine

    2011-02-01

    The effect of thermal annealing on the structure and magnetic properties of crystalline Tb/Fe multilayers has been studied using conversion electron Mössbauer spectrometry and small-angle X-ray diffraction. The growth of Tb–Fe amorphous alloy from the interface is observed with increasing annealing temperature. After annealing at 873 K, a clear total mixing of the multilayers by interdiffusion has been evidenced. The results are compared with the effect of ion irradiation in the same system.

  5. Analysis of the aggregation structure from amphiphilic block copolymers in solutions by small-angle x-ray scattering

    CERN Document Server

    Rong Li Xia; Wang Jun; Wei Liu He; Li Fu Mian; Li Zi Chen

    2002-01-01

    The aggregation structure of polystyrene-p vinyl benzoic amphiphilic block copolymers which were prepared in different conditions was investigated by synchrotron radiation small-angle x-ray scattering (SAXS). The micelle was self-assembled in selective solvents of the block copolymers. Authors' results demonstrate that the structure of the micelle depends on the factors, such as the composition of the copolymers, the nature of the solvent and the concentration of the solution

  6. DMSO-Induced Dehydration of DPPC Membranes Studied by X-ray Diffraction, Small-Angle Neutron Scattering, and Calorimetry

    OpenAIRE

    Kiselev, M. A.; Lesieur, P.; Kisselev, A. M.; Grabielle-Madelmond, C.; Ollivon, M.

    2001-01-01

    The influence of dimethyl sulfoxide (DMSO) on membrane thickness, multilamellar repeat distance, and phase transitions of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) was investigated by X-ray diffraction and small-angle neutron scattering (SANS). The differential scanning calorimetry (DSC) study of water freezing and ice melting was performed in the ternary DPPC /DMSO /water and binary DMSO /water systems. The methods applied demonstrated the differences in membrane structure in t...

  7. INVESTIGATION ON THE CONFORMATION OF THE MAIN-CHAIN NEMATIC POLYMER BY SMALL ANGLE X-RAY SCATTERING

    Institute of Scientific and Technical Information of China (English)

    SUN Zhengmin; WANG Huaqin; WANG Xinjiu

    1990-01-01

    The experimental investigation on the conformation of a thermotropic main-chain nematic polymer by small-angle X-ray scattering (SAXS) has been carried out. The average radius of gyration of the polymer has been determined in nematic and isotropic state respectively. The experiment shows that the boundary between domains is not sharp but diffuse, and the diffuse - boundary thickness of the polymer as a function of temperature has been given.

  8. Method to study sample object size limit of small-angle x-ray scattering computed tomography

    Science.gov (United States)

    Choi, Mina; Ghammraoui, Bahaa; Badal, Andreu; Badano, Aldo

    2016-03-01

    Small-angle x-ray scattering (SAXS) imaging is an emerging medical tool that can be used for in vivo detailed tissue characterization and has the potential to provide added contrast to conventional x-ray projection and CT imaging. We used a publicly available MC-GPU code to simulate x-ray trajectories in a SAXS-CT geometry for a target material embedded in a water background material with varying sample sizes (1, 3, 5, and 10 mm). Our target materials were water solution of gold nanoparticle (GNP) spheres with a radius of 6 nm and a water solution with dissolved serum albumin (BSA) proteins due to their well-characterized scatter profiles at small angles and highly scattering properties. The background material was water. Our objective is to study how the reconstructed scatter profile degrades at larger target imaging depths and increasing sample sizes. We have found that scatter profiles of the GNP in water can still be reconstructed at depths up to 5 mm embedded at the center of a 10 mm sample. Scatter profiles of BSA in water were also reconstructed at depths up to 5 mm in a 10 mm sample but with noticeable signal degradation as compared to the GNP sample. This work presents a method to study the sample size limits for future SAXS-CT imaging systems.

  9. Application of Small Angle X-ray Scattering (SAXS for Differentiation between Normal and Cancerous Breast Tissue

    Directory of Open Access Journals (Sweden)

    2005-07-01

    Full Text Available Introduction: Small angle, between 3° and 10°, X ray scattering is predominantly coherent giving rise to diffraction effects that can be observed as constructive and destructive interferences. These interferences carry information about the molecular structure of the tissue and hence can be used to identify changes that occur due to cancer. Method: In this study an energy dispersive X-ray diffraction method was used. The optimum scattering angle, determined from a series of measurements on adipose breast tissue at several angles from 4 to 7.3 degrees, was found to be 6.5°. Once optimized the system was used to measure the diffraction profiles (corrected scattered intensity versus momentum transfer of a total of 99 breast tissue samples. The samples were both normal and tumour samples. Results: Adipose tissue showed a sharp, high intensity peak at low momentum transfer values of approximately 1.1nm-1. Adipose tissue, mixed tissue (adipose & fibroglandular and tumor have peaks at different values of momentum transfer that can be used to identify the tissue. Benign and malignant breast tissues can also be differentiated by both peak positions and peak heights. It was also observed that the results were reproducible even after the tissue had been preserved at liquid nitrogen temperatures. Conclusion: We were able to differentiate between normal, benign and malignant breast tissues by using energy dispersive small angle x-ray scattering.

  10. Simbol-X Mirror Module Thermal Shields: II-Small Angle X-Ray Scattering Measurements

    International Nuclear Information System (INIS)

    The formation flight configuration of the Simbol-X mission implies that the X-ray mirror module will be open to Space on both ends. In order to reduce the power required to maintain the thermal stability and, therefore, the high angular resolution of the shell optics, a thin foil thermal shield will cover the mirror module. Different options are presently being studied for the foil material of these shields. We report results of an experimental investigation conducted to verify that the scattering of X-rays, by interaction with the thin foil material of the thermal shield, will not significantly affect the performances of the telescope.

  11. Self-assembly of designed coiled coil peptides studied by small-angle X-ray scattering and analytical ultracentrifugation

    DEFF Research Database (Denmark)

    Malik, Leila; Nygaard, Jesper; Christensen, Niels Johan;

    2013-01-01

    α-Helical coiled coil structures, which are noncovalently associated heptad repeat peptide sequences, are ubiquitous in nature. Similar amphipathic repeat sequences have also been found in helix-containing proteins and have played a central role in de novo design of proteins. In addition......, they are promising tools for the construction of nanomaterials. Small-angle X-ray scattering (SAXS) has emerged as a new biophysical technique for elucidation of protein topology. Here, we describe a systematic study of the self-assembly of a small ensemble of coiled coil sequences using SAXS and analytical...

  12. Quaternary structure of alpha-crustacyanin from lobster as seen by small-angle X-ray scattering.

    Science.gov (United States)

    Dellisanti, Cosma D; Spinelli, Silvia; Cambillau, Christian; Findlay, John B C; Zagalsky, Peter F; Finet, Stéphanie; Receveur-Bréchot, Véronique

    2003-06-01

    The structure of alpha-crustacyanin, the blue carotenoprotein of lobster (Homarus gammarus) carapace, has been investigated for the first time using small-angle X-ray scattering. In this paper, we have determined the dimensions of this protein composed of eight heterodimeric subunits of beta-crustacyanin. Analysis of the scattering spectra and estimation of the shape of alpha-crustacyanin show that the protein fits into a cylinder with an axial length of 238 A and a radius of 47.5 A, in which the eight beta-crustacyanin molecules are probably arranged in a helical manner. PMID:12782314

  13. [Prediction of Protein Conformational Mobility and Evaluation of Its Reliability Using Small-Angle X-ray Scattering].

    Science.gov (United States)

    Knyazev, S N; Kalyakin, V Y; Deryabin, I N; Fedorov, B A; Smirnov, A V; Stepanov, E O; Porozov, Yu B

    2015-01-01

    The "coarse-grained" model of protein conformational mobility is presented. We compared the trajectories of conformational motions predicted for five proteins using this model with the motion obtained by the method of the "nearest neighbor", based on small-angle X-ray scattering data. It is shown that for all studied proteins the sequence of conformations calculated on the basis of "coarse-grained" model and on the basis of the "nearest neighbor", coincides well, although there are exceptions. Some separate consideration should be given to each protein to discern the causes of these exceptions. PMID:26841499

  14. Synthesis of a nanorod ferrofluid and characterisation by magnetic-field-dependent small-angle X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Doebrich, F. [Universitaet des Saarlandes, Technische Physik, Geb. D2 2, 66041 Saarbruecken (Germany)]. E-mail: f.doebrich@nano.uni-saarland.de; Michels, A. [Universitaet des Saarlandes, Technische Physik, Geb. D2 2, 66041 Saarbruecken (Germany); Birringer, R. [Universitaet des Saarlandes, Technische Physik, Geb. D2 2, 66041 Saarbruecken (Germany)

    2007-09-15

    Compared to conventional ferrofluids, which contain mostly spherical particles, a dispersion of highly anisometric particles such as rods or chains is expected to give rise to an enhancement or modification of well-known ferrofluid properties. This contribution reports on the synthesis of a ferrofluid containing stable chains of iron nanoparticles and on its microstructural characterisation by means of transmission electron microscopy and small-angle X-ray scattering (SAXS). The SAXS measurements develop a pronounced anisotropy of the scattering pattern as a function of an increasing external magnetic field. Evaluation of the radially averaged SAXS curves in terms of basic scattering functions is discussed.

  15. Determination of biological specimen optimal thickness for small-angle X-ray experiments by use polychromatic synchrotron radiation

    International Nuclear Information System (INIS)

    It is put forward the mode of evaluation of biological specimen optimal thickness for small-angle specimen thickness on various synchrotron radiation spectra are calculated. The curves allow to optimize an experiment by selecting either optimal specimen thickness for an available synchrotron radiation spectrum, or the disposition of the short-wave boundary for given specimen thickness (fibers, tissues and so on). The method gives the possibility apart from increasing both of the precision and reproducibility of X-ray experiments, either or both increase of the statistical precision upon given recording time of an X-ray pattern and decrease recording time upon retention of the same statistical precision. The 15-20 % deviation in the specimen thickness from that of optimal one is shown to lead to decrease in the scattering intensity less than 2 %. 15 refs.; 3 figs

  16. Small-angle X-ray scattering: a bridge between RNA secondary structures and three-dimensional topological structures

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Xianyang [National Inst. of Health (NIH), Bethesda, MD (United States). National Cancer Inst., NCI Small Angle X-ray Scattering Core Facility; Stagno, Jason R. [National Inst. of Health (NIH), Bethesda, MD (United States). National Cancer Inst., Protein-Nucleic Acid Interaction Section, Structural Biophysics Lab.; Bhandari, Yuba R. [National Inst. of Health (NIH), Bethesda, MD (United States). National Cancer Inst., Protein-Nucleic Acid Interaction Section, Structural Biophysics Lab.; Zuo, Xiaobing [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Wang, Yun-Xing [National Inst. of Health (NIH), Bethesda, MD (United States). National Cancer Inst., NCI Small Angle X-ray Scattering Core Facility; National Inst. of Health (NIH), Bethesda, MD (United States). National Cancer Inst., Protein-Nucleic Acid Interaction Section, Structural Biophysics Lab.

    2015-02-01

    Whereas the structures of small to medium-sized well folded RNA molecules often can be determined by either X-ray crystallography or NMR spectroscopy, obtaining structural information for large RNAs using experimental, computational, or combined approaches remains a major interest and challenge. RNA is very sensitive to small-angle X-ray scattering (SAXS) due to high electron density along phosphate-sugar backbones, whose scattering contribution dominates SAXS intensity. For this reason, SAXS is particularly useful in obtaining global RNA structural information that outlines backbone topologies and, therefore, molecular envelopes. Such information is extremely valuable in bridging the gap between the secondary structures and three-dimensional topological structures of RNAmolecules, particularly those that have proven difficult to study using other structuredetermination methods. Here we review published results of RNA topological structures derived from SAXS data or in combination with other experimental data, as well as details on RNA sample preparation for SAXS experiments.

  17. Grazing incidence small angle X-ray scattering study of silver nanoparticles in ion-exchanged glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Weidong, E-mail: 57399942@qq.com [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Wu, Zhaojun [Department of Practice Teaching and Equipment Management, Qiqihar University, Qiqihar 161006 (China); Gu, Xiaohua [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Xing, Xueqing; Mo, Guang [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Wu, Zhonghua, E-mail: wuzh@ihep.ac.cn [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2015-05-15

    The size and distribution of silver nanoparticles in ion-exchanged silicate glass induced by thermal treatments in air at different temperatures were investigated by means of grazing incidence small angle X-ray scattering technique, X-ray diffraction and optical absorption spectra. Silver–sodium ion exchange of soda-lime silicate glasses was done at 350 °C for 240 min, then the samples were treated by thermal annealing in air at different temperatures 400, 500 and 550 °C, respectively, for 1 h. After the annealing treatment above 400 °C for 1 h, smaller Ag nanoparticles occurred, together with bigger ones. Both dissolution of smaller Ag nanoparticles and diffusion of larger ones are discussed in these stages of annealing in this contribution.

  18. Small angle X-ray and neutron scattering from solutions of biological macromolecules

    CERN Document Server

    Svergun, Dmitri I; May, Roland P; Timmins, Peter A

    2013-01-01

    In this book, following the presentation of the basics of scattering from isotropic macromolecular solutions, modern instrumentation, experimental practice and advanced analysis techniques are explained. Advantages of X-rays (rapid data collection, small sample volumes) and of neutrons (contrast variation by hydrogen/deuterium exchange) are specifically highlighted. Examples of applications of the technique to different macromolecular systems are considered with specific emphasis on the synergistic use of SAXS/SANS with other structural, biophysical and computational techniques.

  19. Glitches in Anomalous X-ray Pulsars

    CERN Document Server

    Dib, Rim; Gavriil, Fotis P

    2007-01-01

    (Abridged). We report on 8.7 and 7.6yr of RXTE observations of the Anomalous X-ray Pulsars (AXPs) RXS J170849.0-400910 and 1E 1841-045, respectively. These observations, part of a larger RXTE AXP monitoring program, have allowed us to study the long-term timing, pulsed flux, and pulse profile evolution of these objects. We report on four new glitches, one from RXS J170849.0-400910 and three from 1E 1841-045. One of the glitches from 1E 1841-045 is among the largest ever seen in a neutron star, having fractional frequency jump (delta nu)/nu=1.6E-5. With nearly all known persistent AXPs now seen to glitch, such behavior is clearly generic to this source class. We compare AXP glitches with those in radio pulsars. We show that in terms of fractional frequency change, AXPs are among the most actively glitching neutron stars, with glitch amplitudes in general larger than in radio pulsars. However, in terms of absolute glitch amplitude, AXP glitches are unremarkable. We show that the largest observed AXP glitches sh...

  20. Mineral crystal alignment in mineralized fracture callus determined by 3D small-angle X-ray scattering

    Science.gov (United States)

    Liu, Yifei; Manjubala, Inderchand; Roschger, Paul; Schell, Hanna; Duda, Georg N.; Fratzl, Peter

    2010-10-01

    Callus tissue formed during bone fracture healing is a mixture of different tissue types as revealed by histological analysis. But the structural characteristics of mineral crystals within the healing callus are not well known. Since two-dimensional (2D) scanning small-angle X-ray scattering (sSAXS) patterns showed that the size and orientation of callus crystals vary both spatially and temporally [1] and 2D electron microscopic analysis implies an anisotropic property of the callus morphology, the mineral crystals within the callus are also expected to vary in size and orientation in 3D. Three-dimensional small-angle X-ray scattering (3D SAXS), which combines 2D SAXS patterns collected at different angles of sample tilting, has been previously applied to investigate bone minerals in horse radius [2] and oim/oim mouse femur/tibia [3]. We implement a similar 3D SAXS method but with a different way of data analysis to gather information on the mineral alignment in fracture callus. With the proposed accurate yet fast assessment of 3D SAXS information, it was shown that the plate shaped mineral particles in the healing callus were aligned in groups with their predominant orientations occurring as a fiber texture.

  1. Mineral crystal alignment in mineralized fracture callus determined by 3D small-angle X-ray scattering

    International Nuclear Information System (INIS)

    Callus tissue formed during bone fracture healing is a mixture of different tissue types as revealed by histological analysis. But the structural characteristics of mineral crystals within the healing callus are not well known. Since two-dimensional (2D) scanning small-angle X-ray scattering (sSAXS) patterns showed that the size and orientation of callus crystals vary both spatially and temporally [1] and 2D electron microscopic analysis implies an anisotropic property of the callus morphology, the mineral crystals within the callus are also expected to vary in size and orientation in 3D. Three-dimensional small-angle X-ray scattering (3D SAXS), which combines 2D SAXS patterns collected at different angles of sample tilting, has been previously applied to investigate bone minerals in horse radius [2] and oim/oim mouse femur/tibia [3]. We implement a similar 3D SAXS method but with a different way of data analysis to gather information on the mineral alignment in fracture callus. With the proposed accurate yet fast assessment of 3D SAXS information, it was shown that the plate shaped mineral particles in the healing callus were aligned in groups with their predominant orientations occurring as a fiber texture.

  2. Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

    Directory of Open Access Journals (Sweden)

    Norbert Kučerka

    2015-09-01

    Full Text Available We review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach produces robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition. From model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc..

  3. Automated microfluidic sample-preparation platform for high-throughput structural investigation of proteins by small-angle X-ray scattering

    DEFF Research Database (Denmark)

    Lafleur, Josiane P.; Snakenborg, Detlef; Nielsen, Søren Skou;

    2011-01-01

    A new microfluidic sample-preparation system is presented for the structural investigation of proteins using small-angle X-ray scattering (SAXS) at synchrotrons. The system includes hardware and software features for precise fluidic control, sample mixing by diffusion, automated X-ray exposure co...

  4. A method for sizing sub-micron particles using small angle diffraction of soft x-rays

    International Nuclear Information System (INIS)

    The purpose of this work is to develop a method of sizing sub-micron particles using small-angle soft x-ray diffraction. Solid poly-styrene spheres of known sizes were used as scattering samples, with C-Kα (44.8/angstrom/) and V-Lα (24.3/angstrom/) radiation from a conventional x-ray source. Two devices were used to diffract the x-rays. One collimates the radiation using a series of pinholes immediately preceding the sample, and directs the unfocussed radiation onto film placed far from the sample. The other utilizes radiation from a single pinhole above the source onto the sample and a spherical multilayer mirror in series, so that the radiation passes twice through the sample and is focused onto film immediately above the pinhole assembly to increase the effective sample area. Using the latter device, two types of diffraction patterns were obtained: a sharp, relatively small pattern from spheres which form a hexagonal lattice structure, and a diffuse, larger pattern from an unordered, or random, array of spheres. Both patterns are presented in this work, along with the calculations, based upon light scattering from an unordered and an ordered array of particles, of the scattering patterns. 9 refs., 32 figs., 2 tabs

  5. The microfocus small-angle X-ray scattering at SSRF BL16B1

    CERN Document Server

    Hua, Wenqiang; Zhou, Ping; Li, Xiuhong; Bian, Fenggang; Wang, Jie

    2016-01-01

    Offering high-brilliance X-ray beams on micrometer length scales, the microfocus SAXS at SSRF BL16B1 was established with a KB mirror system for studying small sample volumes, or probing micro-scopic morphologies. The SAXS minimum q value was 0.1nm^-1 with a flux of 1.5 x 10^10photons/s. Two position-resolved scanning experimental methods was combined with microfocus SAXS that include STXM and CT. The experimental results of a standard sample was presented to illustrate the performance of the microfocus SAXS method. Because of the significant smearing effect in the horizontal direction, an effective and easy-to-use desmearing procedure for two-dimensional SAXS pattern based on the blind deconvolution was developed and the deblurring results demonstrated the good restoration effect for the defocus image.

  6. Polypod-Shaped DNAs: Small-Angle X-ray Scattering and Immunostimulatory Activity.

    Science.gov (United States)

    Sanada, Yusuke; Shiomi, Tomoki; Okobira, Tadashi; Tan, Mengmeng; Nishikawa, Makiya; Akiba, Isamu; Takakura, Yoshinobu; Sakurai, Kazuo

    2016-04-19

    We explored in detail the relationship between the structure in aqueous solution and immunostimulatory activity of polypod-shaped DNAs, called polypodnas. The polypodnas were constructed using 3-6 oligodeoxynucleotides (ODNs) to obtain tri-, tetra-, penta-, and hexapodna, each of which had 3, 4, 5, and 6 arms made of double-stranded DNA, respectively. A highly potent immunostimulatory CpG sequence was included into each of the polypodnas. Synchrotron X-ray scattering analysis showed that the double-stranded DNA arms of all of the polypodnas adopted a B-form DNA conformation. The analysis also suggested that some nucleotides in the central parts of pentapodna and hexapodna did not form base pairs, whereas those of tripodna and tetrapodna all formed base pairs. This difference would occur because of an increase in steric hindrance and electrical repulsion with increasing number of arms. The pentapodna and hexapodna induced a large amount of tumor necrosis factor α-release from macrophage-like cells compared with the tripodna and tetrapodna, suggesting that the partly loosened DNA in polypodna with many arms is advantageous for exposing the immunostimulatory sequences of the polypodna. PMID:27007061

  7. Water adsorption and small angle X-ray scattering studies on the effect of coal thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Mitropoulos, A.C.; Haynes, J.M.; Richardson, R.M.; Steriotis, T.A.; Stubos, A.K.; Kanellopoulos, N.K. [University of Bristol, Bristol (United Kingdom). School of Chemistry

    1996-09-01

    The paper studies the interaction of water with two bituminous coal samples which have suffered structural alterations after thermal treatment at a relatively high temperature {approx_equal} (340{degree}C). Weight loss, adsorption, and small angle X-ray scattering (SAXS) experiments where carried out. The results suggest that the mesopore structure in both samples undergoes a partial collapse. A strong hydrophobic effect, at the very early stages of the adsorption process, is noted for only one of them. This observation is attributed to differences in the rigidity of each of the structures. Analysis of the spectra in terms of fractal geometry is also performed. It is proposed that thermal treatment changes the coal matrices from a dilute to a dense configuration. Heating causes a breakage of some oxygen and sulphur bridges giving rise to these structural alterations. 29 refs., 4 figs., 1 tab.

  8. Structure and kinetics of chemically cross-linked protein gels from small-angle X-ray scattering

    CERN Document Server

    Kaieda, Shuji; Halle, Bertil

    2014-01-01

    Glutaraldehyde (GA) reacts with amino groups in proteins, forming intermolecular cross-links that, at sufficiently high protein concentration, can transform a protein solution into a gel. Although GA has been used as a cross-linking reagent for decades, neither the cross-linking chemistry nor the microstructure of the resulting protein gel have been clearly established. Here we use small-angle X-ray scattering (SAXS) to characterise the microstructure and structural kinetics of gels formed by cross-linking of pancreatic trypsin inhibitor, myoglobin or intestinal fatty acid-binding protein. By comparing the scattering from gels and dilute solutions, we extract the structure factor and the pair correlation function of the gel. The protein gels are spatially heterogeneous, with dense clusters linked by sparse networks. Within the clusters, adjacent protein molecules are almost in contact, but the protein concentration in the cluster is much lower than in a crystal. At the $\\sim$ 1 nm SAXS resolution, the native ...

  9. Distribution of Sulfur in Carbon/Sulfur Nanocomposites Analyzed by Small-Angle X-ray Scattering.

    Science.gov (United States)

    Petzold, Albrecht; Juhl, Anika; Scholz, Jonas; Ufer, Boris; Goerigk, Günter; Fröba, Michael; Ballauff, Matthias; Mascotto, Simone

    2016-03-22

    The analysis of sulfur distribution in porous carbon/sulfur nanocomposites using small-angle X-ray scattering (SAXS) is presented. Ordered porous CMK-8 carbon was used as the host matrix and gradually filled with sulfur (20-50 wt %) via melt impregnation. Owing to the almost complete match between the electron densities of carbon and sulfur, the porous nanocomposites present in essence a two-phase system and the filling of the host material can be precisely followed by this method. The absolute scattering intensities normalized per unit of mass were corrected accounting for the scattering contribution of the turbostratic microstructure of carbon and amorphous sulfur. The analysis using the Porod parameter and the chord-length distribution (CLD) approach determined the specific surface areas and filling mechanism of the nanocomposite materials, respectively. Thus, SAXS provides comprehensive characterization of the sulfur distribution in porous carbon and valuable information for a deeper understanding of cathode materials of lithium-sulfur batteries.

  10. Structure of Carbon Nanotube Porins in Lipid Bilayers: An in Situ Small-Angle X-ray Scattering (SAXS) Study.

    Science.gov (United States)

    Tran, Ich C; Tunuguntla, Ramya H; Kim, Kyunghoon; Lee, Jonathan R I; Willey, Trevor M; Weiss, Thomas M; Noy, Aleksandr; van Buuren, Tony

    2016-07-13

    Carbon nanotube porins (CNTPs), small segments of carbon nanotubes capable of forming defined pores in lipid membranes, are important future components for bionanoelectronic devices as they could provide a robust analog of biological membrane channels. In order to control the incorporation of these CNT channels into lipid bilayers, it is important to understand the structure of the CNTPs before and after insertion into the lipid bilayer as well as the impact of such insertion on the bilayer structure. Here we employed a noninvasive in situ probe, small-angle X-ray scattering, to study the integration of CNT porins into dioleoylphosphatidylcholine bilayers. Our results show that CNTPs in solution are stabilized by a monolayer of lipid molecules wrapped around their outer surface. We also demonstrate that insertion of CNTPs into the lipid bilayer results in decreased bilayer thickness with the magnitude of this effect increasing with the concentration of CNTPs. PMID:27322135

  11. X-ray magnetic circular dichroism and small angle neutron scattering study of thiol capped gold nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    de la Venta, J.; Bouzas, V.; Pucci, A.; Laguna-Marco, M. A.; Haskel, D.; Pinel, E. F.; te Velthuis, S. G. E.; Hoffmann, A.; Lal, J.; Bleuel, M.; Ruggeri, G.; de Julian, C.; Garcia, M. A.; Univ. Complutense de Madrid; Inst. de Magnetismo Aplicado UCM; Univ. Pisa; Univ. di Padova

    2009-11-01

    X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 {center_dot} 10{sup -4} was found at the Au L{sub 3} edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M{sub s}, of 0.06 emu/g{sub Au}. SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences.

  12. X-ray magnetic circular dichroism and small angle neutron scattering studies of thiol capped gold nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    de la Venta, J.; Bouzas, V.; Pucci, A.; Laguna-Marco, M. A.; Haskel, D.; te Velthuis, S. G. E; Hoffmann, A.; Lal, J.; Bleuel, M.; Ruggeri, G.; de Julian Fernandez, C.; Garcia, M. A.; Univ.Complutense de Madrid; Inst. de Magnetismo Aplicado; Univ. of Pisa; Lab. di Magnetismo Molecolare

    2009-01-01

    X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 {center_dot} 10{sup -4} was found at the Au L{sub 3} edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M{sub s}, of 0.06 emu/g{sub Au}. SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences.

  13. Characterization of the nanopore structures of PAN-based carbon fiber precursors by small angle X-ray scattering

    Institute of Scientific and Technical Information of China (English)

    WANG De-Hong; HAO Jun-Jie; XING Xue-Qing; MO Guang; GONG Yu; L(U) Chun-Xiang; WU Zhong-Hua

    2011-01-01

    The nanopore structures in precursors are crucial to the performance of PAN-based carbon fibers.hot-stretching filaments(C)and drying-densification filaments(D).Synchrotron radiation small angle X-ray scattering is used to probe and compare the nanopore structures of the four fibers.The nanopore size,discrete volume distribution,nanopore orientation degree along the fiber axis and the porosity are obtained.The results demonstrate that the nanopores are mainly formed in the water-washing stage.During the processes of the subsequent production technologies,the slenderness ratio of nanopores and their orientation degree along the fiber axis increase further and simultaneously,the porosity decreases.These results are helpful for improving the performance of the final carbon fibers.

  14. Ultra-small angle neutron scattering and X-ray tomography studies of caseinate-hydroxyapatite microporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Ritzoulis, C., E-mail: critzou@food.teithe.gr [ATEI of Thessaloniki, PO Box 141, 57400 Thessaloniki (Greece); Strobl, M. [Ruprecht-Karls-University Heidelberg, Physikalisch-Chemisches Institut, Im Neuenheimer Feld 229, 69120 Heidelberg (Germany); Helmholtz Centre Berlin for Materials and Energy (former Hahn-Meitner Institute), SF1, Glienicker Str. 100, 14109 Berlin (Germany); Panayiotou, C. [Aristotle University of Thessaloniki, University Campus (Greece); Choinka, G. [Helmholtz Centre Berlin for Materials and Energy (former Hahn-Meitner Institute), SF1, Glienicker Str. 100, 14109 Berlin (Germany); Tsioptsias, C. [Aristotle University of Thessaloniki, University Campus (Greece); Vasiliadou, C. [KEPAMAH, 22nd April 1, 63100 Polygyros, Chalkidiki (Greece); Vasilakos, V. [University of Crete, Department of Biology, 71409 Heraklion, Crete (Greece); Beckmann, F.; Herzen, J.; Donath, T. [Institute for Materials Research, GKSS-Research Center, 21502 Geesthacht (Germany)

    2010-09-01

    Microporous hydroxyapatite-protein composite materials of bimodal pore size distribution, intended for utilization as bone regeneration scaffolds, have been prepared by means of milk caseinate emulsion droplet templating. Ultra-small angle neutron scattering (USANS) has been utilized in order to obtain information on the size distribution of the smaller pores (less than tens of micrometers), as compared to the emulsions that have been initially used as templates. The samples were subsequently visualized in 3 dimensions using synchrotron radiation X-ray tomography, where information concerning the larger pores has been obtained. The examination of the samples confirmed a strong correlation between the size of the templating droplets and the produced pores. In addition, 1 {mu}m-sized pores appear to adhere to the surface of 20-70 {mu}m pores, providing an irregular surface on the large pore walls, a desirable feature in bone-mimicking materials.

  15. Small-angle X-ray scattering study on pectin-chitosan mixed solutions and thermoreversible gels.

    Science.gov (United States)

    Ventura, Irit; Bianco-Peled, Havazelet

    2015-06-01

    Hot solutions containing pectin and chitosan with pectin weight fraction of 0.75, in acidic pH, demonstrate gelation occurring upon cooling to room temperature. This study explores the origin of this gelation using small angle X-ray scattering (SAXS) as the main experimental tool. Modeling SAXS patterns revealed rigid rod conformation in chitosan solutions, whereas pectin formed a self-avoiding chain. In addition, nanometric aggregates were detected in pectin solutions. Pectin and chitosan in mixed solutions adopted a similar semiflexible conformation. The only sample that created a visually stable gel displayed a different pattern, characteristic to polymers gels. Manipulating the composition by adding urea and salts highlighted the important role of hydrogen bonding, which governs the gelation mechanism. Nevertheless, electrostatic interactions were also found to take part in the gelation. To the best of our knowledge, this is the first comprehensive and systematic SAXS study on these pectin-chitosan mixtures.

  16. Guinier peak analysis for visual and automated inspection of small-angle X-ray scattering data

    Science.gov (United States)

    Putnam, Christopher D.

    2016-01-01

    The Guinier region in small-angle X-ray scattering (SAXS) defines the radius of gyration, R g, and the forward scattering intensity, I(0). In Guinier peak analysis (GPA), the plot of qI(q) versus q 2 transforms the Guinier region into a characteristic peak for visual and automated inspection of data. Deviations of the peak position from the theoretical position in dimensionless GPA plots can suggest parameter errors, problematic low-resolution data, some kinds of intermolecular interactions or elongated scatters. To facilitate automated analysis by GPA, the elongation ratio (ER), which is the ratio of the areas in the pair-distribution function P(r) after and before the P(r) maximum, was characterized; symmetric samples have ER values around 1, and samples with ER values greater than 5 tend to be outliers in GPA analysis. Use of GPA+ER can be a helpful addition to SAXS data analysis pipelines.

  17. A Grazing-Incidence Small-Angle X-Ray Scattering View of Vertically Aligned ZnO Nanowires

    Directory of Open Access Journals (Sweden)

    M. Lučić Lavčević

    2013-01-01

    Full Text Available We report a grazing-incidence small-angle X-ray scattering study of ZnO films with vertically aligned and randomly distributed nanowires, grown through a hydrothermal growth process on nanostructured ZnO seeding coatings and deposited by electron beam evaporation on silicon and glass, respectively. The comparison of the scattering patterns of seeding coatings and nanowires showed that the scattering of vertically aligned nanowires exhibited a specific feature: the dominant characteristic of their scattering patterns is the appearance of fine structure effects around the specular peak. These effects were clarified by the combined reflection and scattering phenomena, suggested for the aligned nanowires-substrate system. Furthermore, they enabled the calculation of the average gyration radius of nanowires in horizontal direction. The calculated value was in good agreement with the radii of nanowires estimated by surface electron microscopy. Therefore, the observed feature in the scattering pattern can serve as evidence of the aligned growth of nanowires.

  18. Nano materials Characterization by Small-angle X-ray Scattering Applied on a Multi-purpose X-ray Diffractometer Platform

    International Nuclear Information System (INIS)

    We present the application of the small-angle X-ray scattering (SAXS) technique for the structural characterization of nano materials. This technique has become available in the laboratory on a multipurpose X-ray diffractometer platform and yields information that is complementary to what can be deduced from XRD (or WAXS) data. Among others SAXS is used for the determination of the size distribution, shape, specific surface area, inner structure and aggregation behavior of nanoparticles. It may also be applied to investigate pore size distributions in meso porous materials as well as ordered nano structures. Several application examples dealing with the characterization of photo catalytic nano powders, porous materials, polymer nano composites, colloidal dispersions, surfactants and related samples will be given. Furthermore, the SAXS technique will be compared and contrasted to complementary experimental techniques, such as dynamic light scattering, ultracentrifugation, electron microscopy, BET measurements and mercury intrusion porosimetry. Whereas this presentation focuses on the application examples of the SAXS technique, a more fundamental and practical introduction will be given within the workshop. (author)

  19. New reactor dedicated to in operando studies of model catalysts by means of surface x-ray diffraction and grazing incidence small angle x-ray scattering

    International Nuclear Information System (INIS)

    A new experimental setup has been developed to enable in situ studies of catalyst surfaces during chemical reactions by means of surface x-ray diffraction (SXRD) and grazing incidence small angle x-ray scattering. The x-ray reactor chamber was designed for both ultrahigh-vacuum (UHV) and reactive gas environments. A laser beam heating of the sample was implemented; the sample temperature reaches 1100 K in UHV and 600 K in the presence of reactive gases. The reactor equipment allows dynamical observations of the surface with various, perfectly mixed gases at controlled partial pressures. It can run in two modes: as a bath reactor in the pressure range of 1-1000 mbars and as a continuous flow cell for pressure lower than 10-3 mbar. The reactor is connected to an UHV preparation chamber also equipped with low energy electron diffraction and Auger spectroscopy. This setup is thus perfectly well suited to extend in situ studies to more complex surfaces, such as epitaxial films or supported nanoparticles. It offers the possibility to follow the chemically induced changes of the morphology, the structure, the composition, and growth processes of the model catalyst surface during exposure to reactive gases. As an example the Pd8Ni92(110) surface structure was followed by SXRD under a few millibars of hydrogen and during butadiene hydrogenation while the reaction was monitored by quadrupole mass spectrometry. This experiment evidenced the great sensitivity of the diffracted intensity to the subtle interaction between the surface atoms and the gas molecules

  20. On the X-ray Spectra of Anomalous X-ray Pulsars and Soft Gamma Repeaters

    OpenAIRE

    Kaspi, Victoria M.; Boydstun, Kristen

    2010-01-01

    We revisit the apparent correlation between soft X-ray band photon index and spin-down rate ύ previously reported for Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) by Marsden & White. Our analysis, improved thanks to new source discoveries, better spectral parameter measurements in previously known sources, and the requirement of source quiescence for parameter inclusion, shows evidence for the previously noted trend, although with greater scatter. This trend supp...

  1. Magnetar-like X-ray bursts from an anomalous X-ray pulsar.

    Science.gov (United States)

    Gavriil, F P; Kaspi, V M; Woods, P M

    2002-09-12

    Anomalous X-ray pulsars (AXPs) are a class of rare X-ray emitting pulsars whose energy source has been perplexing for some 20 years. Unlike other X-ray emitting pulsars, AXPs cannot be powered by rotational energy or by accretion of matter from a binary companion star, hence the designation 'anomalous'. Many of the rotational and radiative properties of the AXPs are strikingly similar to those of another class of exotic objects, the soft-gamma-ray repeaters (SGRs). But the defining property of the SGRs--their low-energy-gamma-ray and X-ray bursts--has not hitherto been observed for AXPs. Soft-gamma-ray repeaters are thought to be 'magnetars', which are young neutron stars whose emission is powered by the decay of an ultra-high magnetic field; the suggestion that AXPs might also be magnetars has been controversial. Here we report two X-ray bursts, with properties similar to those of SGRs, from the direction of the anomalous X-ray pulsar 1E1048.1 - 5937. These events imply a close relationship (perhaps evolutionary) between AXPs and SGRs, with both being magnetars.

  2. Structure investigation of metal ions clustering in dehydrated gel using x-ray anomalous dispersion effect

    CERN Document Server

    Soejima, Y; Sugiyama, M; Annaka, M; Nakamura, A; Hiramatsu, N; Hara, K

    2003-01-01

    The structure of copper ion clusters in dehydrated N-isopropylacrylamide/sodium acrylate (NIPA/SA) gel has been studied by means of small angle X-ray scattering (SAXS) method. In order to distinguish the intensity scattered by Cu ions, the X-ray anomalous dispersion effect around the Cu K absorption edge has been coupled with SAXS. It is found that the dispersion effect dependent on the incident X-ray energy is remarkable only at the momentum transfer q = 0.031 A sup - sup 1 , where a SAXS peak is observed. The results indicate that copper ions form clusters in the dehydrated gel, and that the mean size of clusters is the same as that of SA clusters produced by microphase separation. It is therefore naturally presumed that copper ions are adsorbed into the SA molecules. On the basis of the presumption, a mechanism is proposed for microphase-separation and clustering of Cu ions.

  3. Size Determination of a Liposomal Drug by Small-Angle X-ray Scattering Using Continuous Contrast Variation.

    Science.gov (United States)

    Garcia-Diez, Raul; Gollwitzer, Christian; Krumrey, Michael; Varga, Zoltan

    2016-01-26

    The continuously growing complexity of nanodrugs urges for complementary characterization techniques which can elude the current limitations. In this paper, the applicability of continuous contrast variation in small-angle X-ray scattering (SAXS) for the accurate size determination of a complex nanocarrier is demonstrated on the example of PEGylated liposomal doxorubicin (Caelyx). The mean size and average electron density of Caelyx was determined by SAXS using a gradient of aqueous iodixanol (Optiprep), an iso-osmolar suspending medium. The study is focused on the isoscattering point position and the analysis of the Guinier region of the scattering curves recorded at different solvent densities. An average diameter of (69 ± 5) nm and electron density of (346.2 ± 1.2) nm(-3) were determined for the liposomal formulation of doxorubicin. The response of the liposomal nanocarrier to increasing solvent osmolality and the structure of the liposome-encapsulated doxorubicin after the osmotic shrinkage of the liposome are evaluated with sucrose contrast variation in SAXS and wide-angle X-ray scattering (WAXS). In the case of using sucrose as contrast agent, a clear osmolality threshold at 670 mOsm kg(-1) was observed, above which the liposomal drug carriers start to shrink, though preserving the intraliposomal doxorubicin structure. The average size obtained by this technique is smaller than the value measured by dynamic light scattering (DLS), though this difference is expected due to the hydrodynamic size of the PEG moieties attached to the liposomal surface, which are not probed with solvent contrast variation in SAXS. The advantages and drawbacks of the proposed technique are discussed in comparison to DLS, the most frequently used sizing method in nanomedicine. PMID:26673729

  4. Small-angle scattering computed tomography (SAS-CT) using a Talbot-Lau interferometerand a rotating anode x-ray tube:theory and experiments.

    Science.gov (United States)

    Chen, Guang-Hong; Bevins, Nicholas; Zambelli, Joseph; Qi, Zhihua

    2010-06-01

    X-ray differential phase contrast imaging methods, including projection imaging and the corresponding computed tomography (CT), have been implemented using a Talbot interferometer and either a synchrotron beam line or a low brilliance x-ray source generated by a stationary-anode x-ray tube. From small-angle scattering events which occur as an x-ray propagates through a medium, a signal intensity loss can be recorded and analyzed for an understanding of the micro-structures in an image object. This has been demonstrated using a Talbot-Lau interferometer and a stationary-anode x-ray tube. In this paper, theoretical principles and an experimental implementation of the corresponding CT imaging method are presented. First, a line integral is derived from analyzing the cross section of the small-angle scattering events. This method is referred to as small-angle scattering computed tomography (SAS-CT). Next, a Talbot-Lau interferometer and a rotating-anode x-ray tube were used to implement SAS-CT. A physical phantom and human breast tissue sample were used to demonstrate the reconstructed SAS-CT image volumes.

  5. DMSO-induced dehydration of DPPC membranes studied by x-ray diffraction, small angle neutron scattering and calorimetry

    International Nuclear Information System (INIS)

    The properties of dimethyl sulfoxide (DMSO), a cryoprotector well known for its biological and therapeutic applications, were investigated on lipid membranes by x-ray diffraction, differential scanning calorimetry (DSC) and small angle neutron scattering (SANS). The DSC study of water freezing and melting of ice was performed in the ternary system which consists of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC)/DMSO/water system. The influence of DMSO on the DPPC membrane structure was established in the excess of solvent in the region of DMSO mole fraction from 0.0 to 1.0. The methods applied demonstrated the differences in the membrane structure in three sub-regions of DMSO mole fraction (XDMSO) from 0.0 to 0.3 for the first, from 0.3 to 0.9 for the second, and from 0.9 to 1.0 for the third sub-region. The results for 0.0 ≤ XDMSO ≤ 0.3 can be explained in the framework of DMSO-induced dehydration of intermembrane space

  6. Small angle X-ray scattering coupled with in situ electromechanical probing of nanoparticle-based resistive strain gauges.

    Science.gov (United States)

    Decorde, Nicolas; Sangeetha, Neralagatta M; Viallet, Benoit; Viau, Guillaume; Grisolia, Jérémie; Coati, Alessandro; Vlad, Alina; Garreau, Yves; Ressier, Laurence

    2014-12-21

    A comprehensive study on the electromechanical behavior of nanoparticle-based resistive strain gauges in action through normal and grazing incidence small angle X-ray scattering (SAXS/GISAXS) investigations is presented. The strain gauges were fabricated from arrays of colloidal gold nanoparticle (NP) wires assembled on flexible polyethylene terephthalate and polyimide substrates by convective self-assembly. Microstructural changes (mean interparticle distance variations) within these NP wires under uniaxial stretching estimated by SAXS/GISAXS are correlated to their macroscopic electrical resistance variations. SAXS measurements suggest a linear longitudinal extension and transversal contraction of the NP wires with applied strain (0 to ∼ 13%). The slope of this longitudinal variation is less than unity, implying a partial strain transfer from the substrate to the NP wires. The simultaneously measured electrical resistance of the strain gauges shows an exponential variation within the elastic domain of the substrate deformation, consistent with electron tunnelling through the interparticle gaps. A slower variation observed within the plastic domain suggests the formation of new electronic conduction pathways. Implications of transversal contraction of the NP wires on the directional sensitivities of strain gauges are evaluated by simulating electronic conduction in models mimicking a realistic NP arrangement. A loss of directionality of the NP-based strain gauges due to transversal current flow within the NP wires is deduced. PMID:25371292

  7. Temperature Assisted in-Situ Small Angle X-ray Scattering Analysis of Ph-POSS/PC Polymer Nanocomposite

    Science.gov (United States)

    Yadav, Ramdayal; Naebe, Minoo; Wang, Xungai; Kandasubramanian, Balasubramanian

    2016-07-01

    Inorganic/organic nanofillers have been extensively exploited to impart thermal stability to polymer nanocomposite via various strategies that can endure structural changes when exposed a wide range of thermal environment during their application. In this abstraction, we have utilized temperature assisted in-situ small angle X-ray scattering (SAXS) to examine the structural orientation distribution of inorganic/organic nanofiller octa phenyl substituted polyhedral oligomeric silsesquioxane (Ph-POSS) in Polycarbonate (PC) matrix from ambient temperature to 180 °C. A constant interval of 30 °C with the heating rate of 3 °C/min was utilized to guise the temperature below and above the glass transition temperature of PC followed by thermal gravimetric, HRTEM, FESEM and hydrophobic analysis at ambient temperature. The HRTEM images of Ph-POSS nano unit demonstrated hyperrectangular structure, while FESEM image of the developed nano composite rendered separated phase containing flocculated and overlapped stacking of POSS units in the PC matrix. The phase separation in polymer nanocomposite was further substantiated by thermodynamic interaction parameter (χ) and mixing energy (Emix) gleaned via Accelrys Materials studio. The SAXS spectra has demonstrated duplex peak at higher scattering vector region, postulated as a primary and secondary segregated POSS domain and followed by abundance of secondary peak with temperature augmentation.

  8. Collagen Orientation and Crystallite Size in Human Dentin: A Small Angle X-ray Scattering Study; TOPICAL

    International Nuclear Information System (INIS)

    The mechanical properties of dentin are largely determined by the intertubular dentin matrix, which is a complex composite of type I collagen fibers and a carbonate-rich apatite mineral phase. The authors perform a small angle x-ray scattering (SAXS) study on fully mineralized human dentin to quantify this fiber/mineral composite architecture from the nanoscopic through continuum length scales. The SAXS results were consistent with nucleation and growth of the apatite phase within periodic gaps in the collagen fibers. These mineralized fibers were perpendicular to the dentinal tubules and parallel with the mineralization growth front. Within the plane of the mineralization front, the mineralized collagen fibers were isotropic near the pulp, but became mildly anisotropic in the mid-dentin. Analysis of the data also indicated that near the pulp the mineral crystallites were approximately needle-like, and progressed to a more plate-like shape near the dentino-enamel junction. The thickness of these crystallites,(approx) 5 nm, did not vary significantly with position in the tooth. These results were considered within the context of dentinogenesis and maturation

  9. Small Angle X-ray and Neutron Scattering: Powerful Tools for Studying the Structure of Drug-Loaded Liposomes

    Science.gov (United States)

    Di Cola, Emanuela; Grillo, Isabelle; Ristori, Sandra

    2016-01-01

    Nanovectors, such as liposomes, micelles and lipid nanoparticles, are recognized as efficient platforms for delivering therapeutic agents, especially those with low solubility in water. Besides being safe and non-toxic, drug carriers with improved performance should meet the requirements of (i) appropriate size and shape and (ii) cargo upload/release with unmodified properties. Structural issues are of primary importance to control the mechanism of action of loaded vectors. Overall properties, such as mean diameter and surface charge, can be obtained using bench instruments (Dynamic Light Scattering and Zeta potential). However, techniques with higher space and time resolution are needed for in-depth structural characterization. Small-angle X-ray (SAXS) and neutron (SANS) scattering techniques provide information at the nanoscale and have therefore been largely used to investigate nanovectors loaded with drugs or other biologically relevant molecules. Here we revise recent applications of these complementary scattering techniques in the field of drug delivery in pharmaceutics and medicine with a focus to liposomal carriers. In particular, we highlight those aspects that can be more commonly accessed by the interested users. PMID:27043614

  10. Collagen fibril alignment and deformation during tensile strain of leather: a small-angle X-ray scattering study.

    Science.gov (United States)

    Basil-Jones, Melissa M; Edmonds, Richard L; Norris, Gillian E; Haverkamp, Richard G

    2012-02-01

    The distribution and effect of applied strain on the collagen fibrils that make up leather may have an important bearing on the ultimate strength and other physical properties of the material. While sections of ovine and bovine leather were being subjected to tensile strain up to rupture, synchrotron-based small-angle X-ray scattering (SAXS) spectra were recorded edge-on to the leather at points from the corium to the grain. Measurements of both fibril orientation and collagen d spacing showed that, initially, the fibers reorient under strain, becoming more aligned. As the strain increases (5-10% strain), further fibril reorientation diminishes until, at 37% strain, the d spacing increases by up to 0.56%, indicating that significant tensile forces are being transmitted to individual fibrils. These changes, however, are not uniform through the cross-section of leather and differ between leathers of different strengths. The stresses are taken up more evenly through the leather cross-section in stronger leathers in comparison to weaker leathers, where stresses tended to be concentrated during strain. These observations contribute to our understanding of the internal strains and structural changes that take place in leather under stress.

  11. Poisson's ratio of collagen fibrils measured by small angle X-ray scattering of strained bovine pericardium

    Energy Technology Data Exchange (ETDEWEB)

    Wells, Hannah C.; Sizeland, Katie H.; Kayed, Hanan R.; Haverkamp, Richard G., E-mail: r.haverkamp@massey.ac.nz [School of Engineering and Advanced Technology, Massey University, Private Bag 11222, Palmerston North 4442 (New Zealand); Kirby, Nigel; Hawley, Adrian; Mudie, Stephen T. [Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168 (Australia)

    2015-01-28

    Type I collagen is the main structural component of skin, tendons, and skin products, such as leather. Understanding the mechanical performance of collagen fibrils is important for understanding the mechanical performance of the tissues that they make up, while the mechanical properties of bulk tissue are well characterized, less is known about the mechanical behavior of individual collagen fibrils. In this study, bovine pericardium is subjected to strain while small angle X-ray scattering (SAXS) patterns are recorded using synchrotron radiation. The change in d-spacing, which is a measure of fibril extension, and the change in fibril diameter are determined from SAXS. The tissue is strained 0.25 (25%) with a corresponding strain in the collagen fibrils of 0.045 observed. The ratio of collagen fibril width contraction to length extension, or the Poisson's ratio, is 2.1 ± 0.7 for a tissue strain from 0 to 0.25. This Poisson's ratio indicates that the volume of individual collagen fibrils decreases with increasing strain, which is quite unlike most engineering materials. This high Poisson's ratio of individual fibrils may contribute to high Poisson's ratio observed for tissues, contributing to some of the remarkable properties of collagen-based materials.

  12. Local structure of Ca(2+) induced hydrogels of alginate-oligoguluronate blends determined by small-angle-X-ray scattering.

    Science.gov (United States)

    Yuguchi, Yoshiaki; Hasegawa, Ami; Padoł, Anna Maria; Draget, Kurt Ingar; Stokke, Bjørn Torger

    2016-11-01

    Short oligoguluronates, oligoG's, are reported to affect the ionotropic gelation of alginates both with respect to altered gelation kinetics and elastic properties of the resulting gels. The local structure of Ca(2+) induced changes in oligoguluronates and blends of oligoguluronates and alginates was determined by small angle X-ray scattering (SAXS). Calcium was introduced in the aqueous polysaccharide solutions by in situ release of Ca(2+) from Ca-EGTA. The scattering profiles of the Ca(2+)-induced structures in the alginate-oligoG blends were accounted for by a two-component broken rod-like model, also with an additional term representing structural inhomogeneity by a Debye-Bueche term. Adding oligoG to the alginate yields an increase in the largest cross-sectional radius in the region of fractional Ca(2+) saturation of α-l-GulA units from 0.5 to 1. The time-lapse characterization during the Ca-induced changes in the alginate-oligoG blends shows that oligoG delays the emergence of the more extensive laterally aggregated junction zones.

  13. The morphology of block copolymer micelles in supercritical carbon dioxide by small-angle neutron and X-ray scattering

    International Nuclear Information System (INIS)

    Above its critical point, carbon dioxide forms a supercritical fluid, which promises to be an environmentally responsible replacement for the organic solvents traditionally used in polymerizations. Many lipophilic polymers such as polystyrene (PS) are insol- uble in CO2, though polymerizations may be accomplished via the use of PS-fluoropolymer stabilizers, which act as emulsifying agents. Small-angle neutron and X-ray scattering have been used to show that these molecules form micelles with a CO2-phobic PS core and a CO2-philic fluoropolymer corona. When the PS block was fixed in length and the fluorinated corona block was varied, the number of block copolymer molecules per micelle (six to seven) remained constant. Thus, the coronal block molecular weight exerts negligible influence on the aggregation number, in accordance with the theoretical predictions of Halperin, Tirrell and Lodge [Adv. Polym. Sci. (1992), 100, 31-46]. These observations are relevant to understanding the mechanisms of micellization and solubilization in supercritical fluids. (orig.)

  14. The morphology of block copolymer micelles in supercritical carbon dioxide by small-angle neutron and X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Londono, J.D.; Dharmapurikar, R.; Cochran, H.D.; Wignall, G.D. [Oak Ridge National Lab., TN (United States); McClain, J.B.; Betts, D.E.; Canelas, D.A.; DeSimone, J.M.; Samulski, E.T.; Chillura-Martino, D.; Triolo, R.

    1997-10-01

    Above its critical point, carbon dioxide forms a supercritical fluid, which promises to be an environmentally responsible replacement for the organic solvents traditionally used in polymerizations. Many lipophilic polymers such as polystyrene (PS) are insol- uble in CO{sub 2}, though polymerizations may be accomplished via the use of PS-fluoropolymer stabilizers, which act as emulsifying agents. Small-angle neutron and X-ray scattering have been used to show that these molecules form micelles with a CO{sub 2}-phobic PS core and a CO{sub 2}-philic fluoropolymer corona. When the PS block was fixed in length and the fluorinated corona block was varied, the number of block copolymer molecules per micelle (six to seven) remained constant. Thus, the coronal block molecular weight exerts negligible influence on the aggregation number, in accordance with the theoretical predictions of Halperin, Tirrell and Lodge [Adv. Polym. Sci. (1992), 100, 31-46]. These observations are relevant to understanding the mechanisms of micellization and solubilization in supercritical fluids. (orig.). 24 refs.

  15. Automation and remote access of EMBL small angle X-ray scattering beamline X33 dedicated to biological macromolecules

    International Nuclear Information System (INIS)

    Full text: The small-angle X-ray scattering beamline X33 of the European Molecular Biology Laboratory (EMBL) at the DORIS III storage ring (HASYLAB/DESY) has been dedicated to structural studies of non-crystalline biological systems for more than two decades. In the last several years, the introduction of new optical systems (monochromator, mirror, slits etc) and detector systems (large area image plate Mar345 and PILATUS 1M) leads to an improvement of photon flux by a factor of 3 and a reduction of the exposure time by a factor of 7. Moreover, an automated sample changer has been constructed and in operation since August 2007. The data analysis pipeline consisting of the program suite yields the radius of gyration and forward scattering intensity using Guinier analysis (AutoRg), pair distance distribution function p(r) using indirect Fourier transform method (AutoGNOM), and bead models using ab initio shape determination (DAMMIN and DAMMIF). The results of these analysis which are immediately available after each measurement provides an invaluable tool for data quality control during the data collection. Furthermore, works on remote control of the integrated data collection and analysis software is ongoing and expected to be operated in late 2009 where users can send their samples and control the measurements at home institutes. (author)

  16. Synchrotron small angle X-ray scattering study on the conformation of polystyrene in compressed CO2-toluene mixture

    Institute of Scientific and Technical Information of China (English)

    董宝中; 荣利霞; 柳义; 李丹; 韩布兴; 刘志敏

    2003-01-01

    Synchrotron small angle X-ray scattering (SAXS) was performed to investigate the effect of dissolved CO2 in toluene on the conformation of polystyrene (PS) in the solution. It has been found that the second virial coefficient A2 and the radius of gyration Rg decrease with the increasing antisolvent CO2 pressure. The scattering intensity of PS chain followed l(h)∞h-αunder different antisolvent pressures (0, 0.6, 1.5, 2.4, 3.3, and 4.2 MPa), suggesting that the PS chain has self-similar structure behavior or a fractal structure in the presence of antisolvent CO2.All this reveals a large effect of antisolvent pressure or the solubility of CO2 in the solution on PS structure. The fractal dimensions increase with the increasing antisolvent pressure, indicating that the polymer chain changes from a swollen coil into a rather dense globule in the course of adding antisolvent CO2.

  17. Synchrotron small angle x-ray scattering study of dye-sensitized/-unsensitized TiO2 nanoparticle colloidal solution

    Institute of Scientific and Technical Information of China (English)

    Hong Xin-Guo; Du Lu-Chao; Ye Man-Ping; Weng Yu-Xiang

    2004-01-01

    The wide-gap semiconductor TiO2 nanoparticles with and without dye sensitization have been studied by small angle x-ray scattering using synchrotron radiation. Surface properties of the colloidal TiO2 nanoparticles have been analysed in terms of the surface fractal dimensions (Ds), showing that Ds changes from 3.25 to 2.34 when TiO2nanoparticles are sensitized by ATRA (all-trans-retinoic acid), which reveals that the surface of the particles become relatively smooth after dye sensitization. The size distribution of gyration radius of TiO2 nanoparticles in the colloids M(Rg) has been successfully determined by the Shull-Roess method. The main peak of M(Rg) for the unsensitized TiO2colloid is located at 2.1nm, corresponding to a spherical diameter of 5.4nm, and this value for the ATRA sensitized TiO2increases to 2.4nm, indicating a spherical diameter of 6.4nm. Such a size enlargement of TiO2 nanoparticles suggests that there is a coating of ATRA on the TiO2 surface, supporting the view that a monolayer of the dye has been attached to the surface of the TiO2 nanoparticle.

  18. In situ small-angle X-ray scattering analysis of palladium nanoparticle growth on tobacco mosaic virus nanotemplates.

    Science.gov (United States)

    Manocchi, Amy K; Seifert, Soenke; Lee, Byeongdu; Yi, Hyunmin

    2011-06-01

    We present an examination of palladium (Pd) nanoparticle growth on genetically modified tobacco mosaic virus (TMV1cys) nanotemplates via in situ small-angle X-ray scattering (SAXS). Specifically, we examine the role of the TMV1cys templates in Pd nanoparticle formation through the electroless reduction of Pd precursor by a chemical reducing agent as compared to identical conditions in the absence of the TMV1cys templates. We show that in the presence of TMV1cys, the viral nanotemplates provide preferential growth sites for Pd nanoparticle formation, as no measurable Pd particle growth was observed in the bulk solution. In situ SAXS confirmed that particle formation was due to the rapid adsorption of Pd atoms onto the TMV1cys templates at the very early stage of mixing, rather than adsorption of particles formed in the bulk solution. Importantly, Pd nanoparticles were significantly smaller and more uniform as compared to particle formation in the absence of TMV1cys. The Pd nanoparticle coating density was tunable based on Pd precursor concentration. Finally, we show that Pd particle growth on the TMV1cys templates was highly rapid, and complete within 33 s for most samples, in contrast to slower Pd particle growth in the absence of TMV templates. We envision that the results presented here will be valuable in furthering the fundamental understanding of the role of viral nanotemplates in particle formation, as well as of their utility in a wide range of applications. PMID:21520923

  19. DMSO-Induced Dehydration of DPPC Membranes Studied by X-ray Diffraction, Small-Angle Neutron Scattering, and Calorimetry

    CERN Document Server

    Kiselev, M A; Kisselev, A M; Grabielle-Madelmond, C; Ollivon, M

    1999-01-01

    The influence of dimethyl sulfoxide (DMSO) on membrane thickness, multilamellar repeat distance, and phase transitions of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) was investigated by X-ray diffraction and small-angle neutron scattering (SANS). The differential scanning calorimetry (DSC) study of water freezing and ice melting was performed in the ternary DPPC /DMSO /water and binary DMSO /water systems. The methods applied demonstrated the differences in membrane structure in three sub-regions of the DMSO mole fraction (X_dmso): from 0.0 to 0.3 for the first, from 0.3 to 0.8 for the second, and from 0.9 to 1.0 for the third sub-region. The thickness of the intermembrane solvent at T =20C decreases from 14.4 +/- 1.8 A at X_dmso =0.0 to 7.8 +/- 1.8 A at X_dmso =0.1. The data were used to determine the number of free water molecules in the intermembrane space in the presence of DMSO. The results for 0.0 < X_dmso < 0.3 were explained in the framework of DMSO-induced dehydration of the interme...

  20. Review of the fundamental theories behind small angle X-ray scattering, molecular dynamics simulations, and relevant integrated application.

    Science.gov (United States)

    Boldon, Lauren; Laliberte, Fallon; Liu, Li

    2015-01-01

    In this paper, the fundamental concepts and equations necessary for performing small angle X-ray scattering (SAXS) experiments, molecular dynamics (MD) simulations, and MD-SAXS analyses were reviewed. Furthermore, several key biological and non-biological applications for SAXS, MD, and MD-SAXS are presented in this review; however, this article does not cover all possible applications. SAXS is an experimental technique used for the analysis of a wide variety of biological and non-biological structures. SAXS utilizes spherical averaging to produce one- or two-dimensional intensity profiles, from which structural data may be extracted. MD simulation is a computer simulation technique that is used to model complex biological and non-biological systems at the atomic level. MD simulations apply classical Newtonian mechanics' equations of motion to perform force calculations and to predict the theoretical physical properties of the system. This review presents several applications that highlight the ability of both SAXS and MD to study protein folding and function in addition to non-biological applications, such as the study of mechanical, electrical, and structural properties of non-biological nanoparticles. Lastly, the potential benefits of combining SAXS and MD simulations for the study of both biological and non-biological systems are demonstrated through the presentation of several examples that combine the two techniques. PMID:25721341

  1. Review of the fundamental theories behind small angle X-ray scattering, molecular dynamics simulations, and relevant integrated application

    Directory of Open Access Journals (Sweden)

    Lauren Boldon

    2015-02-01

    Full Text Available In this paper, the fundamental concepts and equations necessary for performing small angle X-ray scattering (SAXS experiments, molecular dynamics (MD simulations, and MD-SAXS analyses were reviewed. Furthermore, several key biological and non-biological applications for SAXS, MD, and MD-SAXS are presented in this review; however, this article does not cover all possible applications. SAXS is an experimental technique used for the analysis of a wide variety of biological and non-biological structures. SAXS utilizes spherical averaging to produce one- or two-dimensional intensity profiles, from which structural data may be extracted. MD simulation is a computer simulation technique that is used to model complex biological and non-biological systems at the atomic level. MD simulations apply classical Newtonian mechanics’ equations of motion to perform force calculations and to predict the theoretical physical properties of the system. This review presents several applications that highlight the ability of both SAXS and MD to study protein folding and function in addition to non-biological applications, such as the study of mechanical, electrical, and structural properties of non-biological nanoparticles. Lastly, the potential benefits of combining SAXS and MD simulations for the study of both biological and non-biological systems are demonstrated through the presentation of several examples that combine the two techniques.

  2. Temperature Assisted in-Situ Small Angle X-ray Scattering Analysis of Ph-POSS/PC Polymer Nanocomposite.

    Science.gov (United States)

    Yadav, Ramdayal; Naebe, Minoo; Wang, Xungai; Kandasubramanian, Balasubramanian

    2016-01-01

    Inorganic/organic nanofillers have been extensively exploited to impart thermal stability to polymer nanocomposite via various strategies that can endure structural changes when exposed a wide range of thermal environment during their application. In this abstraction, we have utilized temperature assisted in-situ small angle X-ray scattering (SAXS) to examine the structural orientation distribution of inorganic/organic nanofiller octa phenyl substituted polyhedral oligomeric silsesquioxane (Ph-POSS) in Polycarbonate (PC) matrix from ambient temperature to 180 °C. A constant interval of 30 °C with the heating rate of 3 °C/min was utilized to guise the temperature below and above the glass transition temperature of PC followed by thermal gravimetric, HRTEM, FESEM and hydrophobic analysis at ambient temperature. The HRTEM images of Ph-POSS nano unit demonstrated hyperrectangular structure, while FESEM image of the developed nano composite rendered separated phase containing flocculated and overlapped stacking of POSS units in the PC matrix. The phase separation in polymer nanocomposite was further substantiated by thermodynamic interaction parameter (χ) and mixing energy (Emix) gleaned via Accelrys Materials studio. The SAXS spectra has demonstrated duplex peak at higher scattering vector region, postulated as a primary and secondary segregated POSS domain and followed by abundance of secondary peak with temperature augmentation. PMID:27436152

  3. Mass-fractal growth in niobia/silsesquioxane mixtures: a small-angle X-ray scattering study

    Science.gov (United States)

    Besselink, Rogier; ten Elshof, Johan E.

    2014-01-01

    The nucleation and growth of niobium pentaethoxide (NPE)-derived clusters in ethanol, through acid-catalyzed hydrolysis/condensation in the presence and absence of the silsesquioxane 1,2-bis(triethoxysilyl)ethane (BTESE), was monitored at 298–333 K by small-angle X-ray scattering. The data were analyzed with a newly derived model for polydisperse mass-fractal-like structures. At 298–313 K in the absence of BTESE the data indicated the development of relatively monodisperse NPE-derived structures with self-preserving polydispersity during growth. The growth exponent was consistent with irreversible diffusion-limited cluster agglomeration. At 333 K the growth exponent was characteristic for fast-gelling reaction-limited cluster agglomeration. The reaction yielded substantially higher degrees of polydispersity. In the presence of BTESE the growth exponents were substantially smaller. The smaller growth exponent in this case is not consistent with irreversible Smoluchowski-type agglomeration. Instead, reversible Lifshitz–Slyozov-type agglomeration seems to be more consistent with the experimental data. PMID:25294980

  4. The Structure of Urease Activiation Complexes Examined by Flexibility Analysis, Mutagenesis, and Small-angle X-ray Scattering Approaches

    Energy Technology Data Exchange (ETDEWEB)

    Quiroz, Soledad [Michigan State University, East Lansing; Sukuru, Sai Chetan K. [Michigan State University, East Lansing; Hausinger, Robert P. [Michigan State University, East Lansing; Kuhn, Leslie A. [Michigan State University, East Lansing; Heller, William T [ORNL

    2008-01-01

    Conformational changes of Klebsiella aerogenes urease apoprotein (UreABC){sub 3} induced upon binding of the UreD and UreF accessory proteins were examined by a combination of flexibility analysis, mutagenesis, and small-angle X-ray scattering (SAXS). ProFlex analysis of urease provided evidence that the major domain of UreB can move in a hinge-like motion to account for prior chemical cross-linking results. Rigidification of the UreB hinge region, accomplished through a G11P mutation, reduced the extent of urease activation, in part by decreasing the nickel content of the mutant enzyme, and by sequestering a portion of the urease apoprotein in a novel activation complex that includes all of the accessory proteins. SAXS analyses of urease, (UreABC-UreD){sub 3}, and (UreABC-UreDF){sub 3} confirm that UreD and UreF bind near UreB at the periphery of the (UreAC){sub 3} structure. This study supports an activation model in which a domain-shifted UreB conformation in (UreABC-UreDF){sub 3} allows CO{sub 2} and nickel ions to gain access to the nascent active site.

  5. A new small-angle X-ray scattering set-up on the crystallography beamline I711 at MAX-lab

    DEFF Research Database (Denmark)

    Knaapila, M.; Svensson, C.; Barauskas, J.;

    2009-01-01

    A small-angle X-ray scattering (SAXS) set-up has recently been developed at beamline I711 at the MAX II storage ring in Lund (Sweden). An overview of the required modifications is presented here together with a number of application examples. The accessible q range in a SAXS experiment is 0.009-0...

  6. Small-angle X-ray scattering studies of metastable intermediates of beta-lactoglobulin isolated after heat-induced aggregation

    DEFF Research Database (Denmark)

    Carrotta, R.; Arleth, L.; Pedersen, J.S.;

    2003-01-01

    Small-angle x-ray scattering was used for studying intermediate species, isolated after heat-induced aggregation of the A variant of bovine P-lactoglobulin. The intermediates were separated in two fractions, the heated metastable dimer and heated metastable oligomers larger than the dimer. The pa...

  7. Investigation of the solid surface structural inhomogeneities by the 'combined' small-angle X-ray scattering and Hg porosimetry methods

    Science.gov (United States)

    Skatkov, L. I.; Cheremskoy, P. G.; Gomozov, V. P.; Bayrachny, B. I.

    1996-08-01

    The surface inhomogeneities, i.e. submicropores of porous solids, were investigated by combination of the small-angle X-ray scattering (SAXS) [1-4] and Hg porosimetry methods [5,6]. An optimal approximation of the submicropore shapes and correlation between the shape and the radius of the pores was obtained. The fractal nature of the investigated structure was shown.

  8. ``Ordered'' structure in dilute solutions of sodium polystyrenesulfonates as studied by small-angle x-ray scattering

    Science.gov (United States)

    Ise, Norio; Okubo, Tsuneo; Kunugi, Shigeru; Matsuoka, Hideki; Yamamoto, K.; Ishii, Yasuo

    1984-10-01

    The small angle x-ray scattering measurements were performed for aqueous solutions of sodium polystyrenesulfonates having relatively narrow molecular weight distributions. As was observed for other synthetic macroions, polynucleotide and proteins, a single, broad peak was observed. The scattering vector at the peak position (Sm) was shifted toward larger values with increasing polymer concentration and toward lower values with increasing salt concentration, which confirmed earlier observations with polyacrylate and poly-L-lysine. The molecular weight dependence of the scattering behavior, which was earlier observed, was confirmed to be true for samples with Mw of 74 000, 18 000, and 4600. The mixture of two fractions with different Mw's gave a scattering curve which was again different from the composite curve obtained with the parent curves before mixing. A similar situation was observed for the mixture of polystyrenesulfonate and polyacrylate. Thus, it was concluded that the observed single peak indicates the presence of an intermolecular ordering, not an intramolecular ordering. The intermacroion distance (2Dexp) was thus calculated by using the Bragg equation. 2Dexp decreased with increasing polymer concentration and increased (not decreased) with increasing concentration of added salt and Mw. The 2Dexp values thus obtained were smaller beyond the experimental error than 2D0, a theoretical distance calculated from the concentration by assuming the uniform distribution of the macroions throughout the solution and the 2D0/2Dexp value amounted to 3.5 for high molecular weight samples. This fact indicates the presence of an intermacroion attractive interaction. When two fractions with different Mw's were compared at a given number concentration of macroions, the 2Dexp value for the sample of a larger Mw was smaller than that for the fraction of a smaller Mw. This implies that the attraction must be intensified, though unexpectedly, with increasing valency of the

  9. Ca2+-induced structural changes in phosphorylase kinase detected by small-angle x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Priddy, Timothy S. [University of Missouri and University of Kansas Medical Center; Macdonald, Brian A. [Los Alamos National Laboratory (LANL); Heller, William T [ORNL; Nadeau, Owen W. [University of Kansas Medical Center; Trewhella, Jill [Los Alamos National Laboratory (LANL); Carlson, Gerald M. [University of Kansas Medical Center

    2005-01-01

    Phosphorylase kinase (PhK), a 1.3-MDa ({alpha}{beta}{gamma}{delta}){sub 4} hexadecameric complex, is a Ca{sup 2+}-dependent regulatory enzyme in the cascade activation of glycogenolysis. PhK comprises two arched ({alpha}{beta}{gamma}{delta}){sub 2} octameric lobes that are oriented back-to-back with overall D{sub 2} symmetry and joined by connecting bridges. From chemical cross-linking and electron microscopy, it is known that the binding of Ca{sup 2+} by PhK perturbs the structure of all its subunits and promotes redistribution of density throughout both its lobes and bridges; however, little is known concerning the interrelationship of these effects. To measure structural changes induced by Ca{sup 2+} in the PhK complex in solution, small-angle X-ray scattering was performed on nonactivated and Ca{sup 2+}-activated PhK. Although the overall dimensions of the complex were not affected by Ca{sup 2+}, the cation did promote a shift in the distribution of the scattering density within the hydrated volume occupied by the PhK molecule, indicating a Ca{sup 2+}-induced conformational change. Computer-generated models, based on elements of the known structure of PhK from electron microscopy, were constructed to aid in the interpretation of the scattering data. Models containing two ellipsoids and four cylinders to represent, respectively, the lobes and bridges of the PhK complex provided theoretical scattering profiles that accurately fit the experimental data. Structural differences between the models representing the nonactivated and Ca{sup 2+}-activated conformers of PhK are consistent with Ca{sup 2+}-induced conformational changes in both the lobes and the interlobal bridges.

  10. Measurement of carbon condensates using small-angle x-ray scattering during detonation of the high explosive hexanitrostilbene

    Energy Technology Data Exchange (ETDEWEB)

    Bagge-Hansen, M.; Lauderbach, L.; Hodgin, R.; Bastea, S.; Fried, L.; Jones, A.; Buuren, T. van; Hansen, D.; Benterou, J.; May, C.; Willey, T. M., E-mail: willey1@llnl.gov [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Graber, T. [Washington State University, Pullman, Washington 99164 (United States); Jensen, B. J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Ilavsky, J. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2015-06-28

    The dynamics of carbon condensation in detonating high explosives remains controversial. Detonation model validation requires data for processes occurring at nanometer length scales on time scales ranging from nanoseconds to microseconds. A new detonation endstation has been commissioned to acquire and provide time-resolved small-angle x-ray scattering (SAXS) from detonating explosives. Hexanitrostilbene (HNS) was selected as the first to investigate due to its ease of initiation using exploding foils and flyers, vacuum compatibility, high thermal stability, and stoichiometric carbon abundance that produces high carbon condensate yields. The SAXS data during detonation, collected with 300 ns time resolution, provide unprecedented signal fidelity over a broad q-range. This fidelity permits the first analysis of both the Guinier and Porod/power-law regions of the scattering profile during detonation, which contains information about the size and morphology of the resultant carbon condensate nanoparticles. To bolster confidence in these data, the scattering angle and intensity were additionally cross-referenced with a separate, highly calibrated SAXS beamline. The data show that HNS produces carbon particles with a radius of gyration of 2.7 nm in less than 400 ns after the detonation front has passed, and this size and morphology are constant over the next several microseconds. These data directly contradict previous pioneering work on RDX/TNT mixtures and TATB, where observations indicate significant particle growth (50% or more) continues over several microseconds. The power-law slope is about −3, which is consistent with a complex disordered, irregular, or folded sp{sup 2} sub-arrangement within a relatively monodisperse structure possessing radius of gyration of 2.7 nm after the detonation of HNS.

  11. EXPRESSION, PURIFICATION, AND SMALL ANGLE X-RAY SCATTERING OF DNA REPLICATION AND REPAIR PROTEINS FROM THE HYPERTHERMOPHILE SULFOLOBUS SOLFATARICUS

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, S.M.; Hatherill, J.R.; Hammel, M.; Hura, G.L.; Tainer, J.A.; Yannone, S.M.

    2008-01-01

    Vital molecular processes such as DNA replication, transcription, translation, and maintenance occur through transient protein interactions. Elucidating the mechanisms by which these protein complexes and interactions function could lead to treatments for diseases related to DNA damage and cell division control. In the recent decades since its introduction as a third domain, Archaea have shown to be simpler models for complicated eukaryotic processes such as DNA replication, repair, transcription, and translation. Sulfolobus solfataricus is one such model organism. A hyperthermophile with an optimal growth temperature of 80°C, Sulfolobus protein-protein complexes and transient protein interactions should be more stable at moderate temperatures, providing a means to isolate and study their structure and function. Here we provide the initial steps towards characterizing three DNA-related Sulfolobus proteins with small angle X-ray scattering (SAXS): Sso0257, a cell division control and origin recognition complex homolog, Sso0768, the small subunit of the replication factor C, and Sso3167, a Mut-T like protein. SAXS analysis was performed at multiple concentrations for both short and long exposure times. The Sso0257 sample was determined to be either a mixture of monomeric and dimeric states or a population of dynamic monomers in various conformational states in solution, consistent with a fl exible winged helix domain. Sso0768 was found to be a complex mixture of multimeric states in solution. Finally, molecular envelope reconstruction from SAXS data for Sso3167 revealed a novel structural component which may function as a disordered to ordered region in the presence of its substrates and/or protein partners.

  12. Larger scale structures in starch granules chartacterised via small-angle neutron and x-ray scattering

    International Nuclear Information System (INIS)

    Starch is the primary carbohydrate component in the human diet and the major storage polysaccharide in plants. Small angle scattering (SAS) techniques have an extensive track record in illuminating the semi-crystalline lamellar structure of the starch granule, however, there have been few attempts to use SAS techniques to characterise larger-scale structures reported from imaging techniques, such as growth rings, blocklets or pores. In this study, SAS data collected over an extended q range were gathered from dry and hydrated starch powders of various botanical origins. The use of neutrons and x-rays, as well as comparing dry and hydrated granules, allowed different levels of contrast in scattering length density to be probed and therefore selected structural regions to be highlighted. SAXS measurements were obtained with the Bruker Nanostar, whilst SANS measurements taken at the QUOKKA instrument, ANSTO. Data were analysed with the 'unified' method, which fits SAS curves from hierarchical structures, with each level consisting of a Guinier and Porod component which can be refined during fitting. The lowest q range, 0.002 - 0.04 Å-1, was found to be dominated by scattering from the starch granules themselves, especially in the dry powders; however an inflection point from a low contrast structure was observed at 0.035 Å-1. The associated scattering was interpreted within a unified scattering framework with the inflexion point correlating with a structure with radius of gyration -90 Å - a size comparable to small blocklets or superhelices. In hydrated starches, it is observed that there is an inflection point between lamellar and q-4 power-law scattering regions at approximately 0.004 Å-1 which may correlate with growth rings and large blocklets. The implications of these findings on existing models of starch lamellar scattering are discussed.

  13. Studying nanostructure gradients in injection-molded polypropylene/montmorillonite composites by microbeam small-angle x-ray scattering

    International Nuclear Information System (INIS)

    The core–shell structure in oriented cylindrical rods of polypropylene (PP) and nanoclay composites (NCs) from PP and montmorillonite (MMT) is studied by microbeam small-angle x-ray scattering (SAXS). The structure of neat PP is almost homogeneous across the rod showing regular semicrystalline stacks. In the NCs the discrete SAXS of arranged crystalline PP domains is limited to a skin zone of 300 μm thickness. Even there only frozen-in primary lamellae are detected. The core of the NCs is dominated by diffuse scattering from crystalline domains placed at random. The SAXS of the MMT flakes exhibits a complex skin–core gradient. Both the direction of the symmetry axis and the apparent perfection of flake-orientation are varying. Thus there is no local fiber symmetry, and the structure gradient cannot be reconstructed from a scan across the full rod. To overcome the problem the rods are machined. Scans across the residual webs are performed. For the first time webs have been carved out in two principal directions. Comparison of the corresponding two sets of SAXS patterns demonstrates the complexity of the MMT orientation. Close to the surface (< 1 mm) the flakes cling to the wall. The variation of the orientation distribution widths indicates the presence of both MMT flakes and grains. The grains have not been oriented in the flowing melt. An empirical equation is presented which describes the variation from skin to core of one component of the inclination angle of flake-shaped phyllosilicate filler particles. (paper)

  14. Measurement of carbon condensation using small-angle x-ray scattering during detonation of the high explosive hexanitrostilbene

    Energy Technology Data Exchange (ETDEWEB)

    Bagge-Hansen, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lauderbach, L. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hodgin, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bastea, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fried, L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jones, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); van Buuren, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hansen, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Benterou, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); May, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Graber, T. [Washington State Univ., Pullman, WA (United States); Jensen, B. J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ilavsky, J. [Argonne National Lab. (ANL), Argonne, IL (United States); Willey, T. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-06-24

    The dynamics of carboncondensation in detonating high explosives remains controversial. Detonation model validation requires data for processes occurring at nanometer length scales on time scales ranging from nanoseconds to microseconds. A new detonation endstation has been commissioned to acquire and provide time-resolved small-angle x-ray scattering (SAXS) from detonating explosives. Hexanitrostilbene (HNS) was selected as the first to investigate due to its ease of initiation using exploding foils and flyers, vacuum compatibility, high thermal stability, and stoichiometric carbon abundance that produces high carbon condensate yields. The SAXS data during detonation, collected with 300 ns time resolution, provide unprecedented signal fidelity over a broad q-range. This fidelity permits the first analysis of both the Guinier and Porod/power-law regions of the scattering profile during detonation, which contains information about the size and morphology of the resultant carbon condensate nanoparticles. To bolster confidence in these data, the scattering angle and intensity were additionally cross-referenced with a separate, highly calibrated SAXS beamline. The data show that HNS produces carbon particles with a radius of gyration of 2.7 nm in less than 400 ns after the detonation front has passed, and this size and morphology are constant over the next several microseconds. These data directly contradict previous pioneering work on RDX/TNT mixtures and TATB, where observations indicate significant particle growth (50% or more) continues over several microseconds. As a result, the power-law slope is about –3, which is consistent with a complex disordered, irregular, or folded sp2 sub-arrangement within a relatively monodisperse structure possessing radius of gyration of 2.7 nm after the detonation of HNS.

  15. Small angle x-ray scattering study on the conformation of polystyrene in toluene during adding anti-solvent CO2

    Institute of Scientific and Technical Information of China (English)

    柳义; 陈东风; 王洪立; 陈娜; 李丹; 韩布兴; 荣利霞; 赵辉; 王俊; 董宝中

    2002-01-01

    The conformation of polystyrene in the anti-solvent process of supercritical fluids (compressed CO2 + polystyrene + toluene) has been studied by small angle x-ray scattering with synchrotron radiation as an x-ray source. Coilto-globule transformation of the polystyrene chain was observed with the increase of the anti-solvent CO2 pressure;i.e. polystyrene coiled at a pressure lower than the cloud point pressure (Pc) and turned into a globule with a uniform density at pressures higher than Pc. Fractal behaviour was also found in the chain contraction, and the mass fractal dimension increased with increasing CO2 pressure.

  16. Synchrotron Small-Angle X-Ray Scattering Investigation on Integral Membrane Protein Light-Harvesting Complex LH2 from Photosynthetic Bacterium Rhodopseudomonas Acidophila

    Institute of Scientific and Technical Information of China (English)

    DU Lu-Chao; WENG Yu-Xiang; HONG Xin-Guo; XIAN Ding-Chang; Kobayashi Katsumi

    2006-01-01

    @@ Structures of membrane protein in solution are different from that in crystal phase. We present the primary results of small angle x-ray scattering (SAXS) resolved topological structures of a light harvesting antenna membrane protein complex LH2 from photosynthetic bacteria Rhodopseudomonas acidophila in detergent solution for the first time. Our results show that the elliptical shape of the LH2 complex in solution clearly deviates from its circular structure in crystal phase determined by x-ray diffraction. This result provides an insight into the structure and function interplay in LH2.

  17. Study of the gel films of Acetobacter Xylinum cellulose and its modified samples by 1H NMR cryoporometry and small-angle X-ray scattering

    International Nuclear Information System (INIS)

    Gel films of Acetobacter Xylinum cellulose and its modified samples have been investigated by 1H nuclear magnetic resonance (NMR) cryoporometry and small-angle X-ray scattering. The joint use of these two methods made it possible to characterize the sizes of aqueous pores in gel films and estimate the sizes of structural inhomogeneities before and after the sorption of polyvinylpyrrolidone and Se0 nanoparticles (stabilized by polyvinylpyrrolidone) into the films. According to small-angle X-ray scattering data, the sizes of inhomogeneities in a gel film change only slightly upon the sorption of polyvinylpyrrolidone and nanoparticles. The impregnated material is sorbed into water-filled cavities that are present in the gel film. 1H NMR cryoporometry allowed us to reveal the details of changes in the sizes of small aqueous pores during modifications.

  18. Study of the gel films of Acetobacter Xylinum cellulose and its modified samples by {sup 1}H NMR cryoporometry and small-angle X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Babushkina, T. A.; Klimova, T. P. [Russian Academy of Sciences, Nesmeyanov Institute of Organoelement Compounds (Russian Federation); Shtykova, E. V.; Dembo, K. A.; Volkov, V. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Khripunov, A. K. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation); Klechkovskaya, V. V., E-mail: klechvv@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2010-03-15

    Gel films of Acetobacter Xylinum cellulose and its modified samples have been investigated by 1H nuclear magnetic resonance (NMR) cryoporometry and small-angle X-ray scattering. The joint use of these two methods made it possible to characterize the sizes of aqueous pores in gel films and estimate the sizes of structural inhomogeneities before and after the sorption of polyvinylpyrrolidone and Se{sub 0} nanoparticles (stabilized by polyvinylpyrrolidone) into the films. According to small-angle X-ray scattering data, the sizes of inhomogeneities in a gel film change only slightly upon the sorption of polyvinylpyrrolidone and nanoparticles. The impregnated material is sorbed into water-filled cavities that are present in the gel film. {sup 1}H NMR cryoporometry allowed us to reveal the details of changes in the sizes of small aqueous pores during modifications.

  19. In-situ small-angle x-ray scattering study of nanoparticles in the plasma plume induced by pulsed laser irradiation of metallic targets

    Energy Technology Data Exchange (ETDEWEB)

    Lavisse, L.; Jouvard, J.-M.; Girault, M.; Potin, V.; Andrzejewski, H.; Marco de Lucas, M. C.; Bourgeois, S. [Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Universite de Bourgogne, 9 Avenue A. Savary, BP 47870-21078 Dijon Cedex (France); Le Garrec, J.-L.; Carles, S.; Mitchell, J. B. A. [Institut de Physique de Rennes, UMR 6251 CNRS-Universite de Rennes 1, 35042 Rennes Cedex (France); Hallo, L. [CEA CESTA, 15 Avenue des Sablieres CS 60001, 33116 Le Barp Cedex (France); Perez, J. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint-Aubin, F-91192 Gif-sur-Yvette Cedex (France); Decloux, J. [Kaluti System, Optique et Laser, Centre Scientifique d' Orsay, 91400 Orsay (France)

    2012-04-16

    Small angle x-ray scattering was used to probe in-situ the formation of nanoparticles in the plasma plume generated by pulsed laser irradiation of a titanium metal surface under atmospheric conditions. The size and morphology of the nanoparticles were characterized as function of laser irradiance. Two families of nanoparticles were identified with sizes on the order of 10 and 70 nm, respectively. These results were confirmed by ex-situ transmission electron microscopy experiments.

  20. On the X-ray Spectra of Anomalous X-ray Pulsars and Soft Gamma Repeaters

    CERN Document Server

    Kaspi, Victoria M

    2010-01-01

    We revisit the apparent correlation between soft X-ray band photon index and spin-down rate nudot previously reported for Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) by Marsden & White (2001). Our analysis, improved thanks to new source discoveries, better spectral parameter measurements in previously known sources, and the requirement of source quiescence for parameter inclusion, shows evidence for the previously noted trend, although with greater scatter. This trend supports the twisted magnetosphere model of magnetars although the scatter suggests that factors other than nudot are also important. We also note possible correlations involving the spectra of AXPs and SGRs in the hard X-ray band. Specifically, the hard-band photon index shows a possible correlation with inferred nudot and B, as does the degree of spectral turnover. If the former trend is correct, then the hard-band photon index for AXP 1E 1048.1-5937 should be ~0--1. This may be testable with long integrations by INTEGRA...

  1. Long-Term Monitoring of Anomalous X-ray Pulsars

    CERN Document Server

    Gavriil, F P; Chakraborty, D; Gavriil, Fotis P.; Kaspi, Victoria M.; Chakrabarty, Deepto

    2001-01-01

    We report on long-term monitoring of anomalous X-ray pulsars (AXPs) using the Rossi X-ray Timing Explorer. Using phase-coherent timing, we find a wide variety of behaviors among the sources, ranging from high stability (in 1E 2259.1+586 and 4U 0142+61), to instabilities so severe that phase-coherent timing is not possible (in 1E 1048.1-5937). We note a correlation in which timing stability in AXPs decreases with increasing spin-down rate. The timing stability of soft gamma repeaters in quiescence is consistent with this trend, which is similar to one seen in radio pulsars. We consider high signal-to-noise ratio average pulse profiles as a function of energy for each AXP, and find a variety of behaviors. We find no large variability in pulse morphology nor in pulsed flux as a function of time.

  2. Beyond simple small-angle X-ray scattering: developments in online complementary techniques and sample environments

    Directory of Open Access Journals (Sweden)

    Wim Bras

    2014-11-01

    Full Text Available Small- and wide-angle X-ray scattering (SAXS, WAXS are standard tools in materials research. The simultaneous measurement of SAXS and WAXS data in time-resolved studies has gained popularity due to the complementary information obtained. Furthermore, the combination of these data with non X-ray based techniques, via either simultaneous or independent measurements, has advanced understanding of the driving forces that lead to the structures and morphologies of materials, which in turn give rise to their properties. The simultaneous measurement of different data regimes and types, using either X-rays or neutrons, and the desire to control parameters that initiate and control structural changes have led to greater demands on sample environments. Examples of developments in technique combinations and sample environment design are discussed, together with a brief speculation about promising future developments.

  3. Spectral Properties of Anomalous X-ray Pulsars

    Institute of Scientific and Technical Information of China (English)

    Ye Lu; Wei Wang; Yong-Heng Zhao

    2003-01-01

    We examine the spectra of the persistent emission from anomalous X-ray pulsars (AXPs) and their variation with the spin-down rate Ω. Based on an accretion-powered model, the influences of both the magnetic field and the mass accretion rate on the spectral properties of AXPs are addressed. We then investigate the relation between the spectral property of AXPs and mass accretion rate M. The result shows that there exists a linear correlation between the photon index and the mass accretion rate: the spectral hardness increases with increasing M. A possible emission mechanism for the explanation of the spectral properties of AXPs is also discussed.

  4. GENFIT: software for the analysis of small-angle X-ray and neutron scattering data of macro­molecules in solution

    Science.gov (United States)

    Spinozzi, Francesco; Ferrero, Claudio; Ortore, Maria Grazia; De Maria Antolinos, Alejandro; Mariani, Paolo

    2014-01-01

    Many research topics in the fields of condensed matter and the life sciences are based on small-angle X-ray and neutron scattering techniques. With the current rapid progress in source brilliance and detector technology, high data fluxes of ever-increasing quality are produced. In order to exploit such a huge quantity of data and richness of information, wider and more sophisticated approaches to data analysis are needed. Presented here is GENFIT, a new software tool able to fit small-angle scattering data of randomly oriented macromolecular or nanosized systems according to a wide list of models, including form and structure factors. Batches of curves can be analysed simultaneously in terms of common fitting parameters or by expressing the model parameters via physical or phenomenological link functions. The models can also be combined, enabling the user to describe complex heterogeneous systems. PMID:24904247

  5. GENFIT: software for the analysis of small-angle X-ray and neutron scattering data of macro-molecules in solution.

    Science.gov (United States)

    Spinozzi, Francesco; Ferrero, Claudio; Ortore, Maria Grazia; De Maria Antolinos, Alejandro; Mariani, Paolo

    2014-06-01

    Many research topics in the fields of condensed matter and the life sciences are based on small-angle X-ray and neutron scattering techniques. With the current rapid progress in source brilliance and detector technology, high data fluxes of ever-increasing quality are produced. In order to exploit such a huge quantity of data and richness of information, wider and more sophisticated approaches to data analysis are needed. Presented here is GENFIT, a new software tool able to fit small-angle scattering data of randomly oriented macromolecular or nanosized systems according to a wide list of models, including form and structure factors. Batches of curves can be analysed simultaneously in terms of common fitting parameters or by expressing the model parameters via physical or phenomenological link functions. The models can also be combined, enabling the user to describe complex heterogeneous systems.

  6. The Use of Small-Angle X-Ray Diffraction Studies for the Analysis of Structural Features in Archaeological Samples

    DEFF Research Database (Denmark)

    Wess, T. J.; Drakopoulos, M.; Snigirev, A.;

    2001-01-01

    the potential of a laboratory source is also described. Specific examples of analysis using X-ray diffraction of historic parchment, archaeological bone, a Central Mexico style pictograph and microdiffraction of calcified tissues are used to show the scope and versatility of the technique. Diffraction data...

  7. Small-angle X-ray scattering investigation of aging behavior of Al-Cu-Mg-Ag alloys using synchrotron radiation

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The aging behavior of Al-Cu-Mg-Ag alloys with high Cu/Mg was studied by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) using synchrotron radiation. TEM study reveals that the major strengthening phases of the alloy after aging at 160?C for 10 h are Ω and less θ′. SAXS study shows that the scattering patterns are composed of several concentric circles at the beginning of aging process, which is replaced by the butterfly-wings scattering patterns with the increase of aging time...

  8. Salt Dependence of the Radius of Gyration and Flexibility of Single-stranded DNA in Solution probed by Small-angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Adelene Y.L.; Lipfert, Jan; Herschlag, Daniel; Doniach, Sebastian

    2012-07-06

    Short single-stranded nucleic acids are ubiquitous in biological processes and understanding their physical properties provides insights to nucleic acid folding and dynamics. We used small angle x-ray scattering to study 8-100 residue homopolymeric single-stranded DNAs in solution, without external forces or labeling probes. Poly-T's structural ensemble changes with increasing ionic strength in a manner consistent with a polyelectrolyte persistence length theory that accounts for molecular flexibility. For any number of residues, poly-A is consistently more elongated than poly-T, likely due to the tendency of A residues to form stronger base-stacking interactions than T residues.

  9. Small-angle x-ray scattering and differential scanning calorimetry studies of DPPC multilamellar structures containing membranotropic agents of different chemical nature

    International Nuclear Information System (INIS)

    Multilamellar structures formed in DPPC/water/glycerol and DPPC/water/oxyethylated glycerol systems are studied by small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) methods. The effects of glycerol, oxyethylated glycerol, and other membranotropic agents (MTAs) on the lamellar repeat distance D are compared in gel, ripple, and high-temperature (Lα) liquid crystal phases of the hydrated phospholipids. It is noted that the introduction of MTAs could lead to different types of 'D vs. temperature' behavior in the Lα phase, which is correlated with changes in D caused by the introduction of these substances to the DPPC/water reference system

  10. Small-angle X-ray scattering study of the growth kinetics of CuCl nanocrystals in NaCl

    OpenAIRE

    Kranold, R.; Kriesen, S.; Haselhoff, M.; Weber, H.-J.; Goerigk, G.

    2003-01-01

    The precipitation of CuCl nanocrystals in a NaCl matrix has been studied by time-resolved small-angle X-ray scattering. The experimental results suggest that the nucleation process is accelerated by lattice defects of the matrix remaining in the NaCl lattice after the dissolution of previous nanocrystals at high temperature. The evolution of structural parameters calculated from the scattering curves, such as volume fraction, mean radius and particle number density of the nanocrystals, is dis...

  11. Precision Timing of Two Anomalous X-Ray Pulsars.

    Science.gov (United States)

    Kaspi; Chakrabarty; Steinberger

    1999-11-01

    We report on long-term X-ray timing of two anomalous X-ray pulsars, 1RXS J170849.0-400910 and 1E 2259+586, using the Rossi X-Ray Timing Explorer. In monthly observations made over 1.4 and 2.6 yr for the two pulsars, respectively, we have obtained phase-coherent timing solutions which imply that these objects have been rotating with great stability throughout the course of our observations. For 1RXS J170849.0-400910, we find a rotation frequency of 0.0909169331(5) Hz and frequency derivative -15.687&parl0;4&parr0;x10-14 Hz s-1 for epoch MJD 51215.931. For 1E 2259+586, we find a rotation frequency of 0.1432880613(2) Hz and frequency derivative -1.0026&parl0;7&parr0;x10-14 Hz s-1 for epoch MJD 51195.583. The rms phase residuals from these simple models are only approximately 0.01 cycles for both sources. We show that the frequency derivative for 1E 2259+586 is inconsistent with that inferred from incoherent frequency observations made over the last 20 yr. Our observations are consistent with the magnetar hypothesis and make binary accretion scenarios appear unlikely.

  12. Gas gain operations with single photon resolution using an integrating ionization chamber in small-angle X-ray scattering experiments

    CERN Document Server

    Menk, R H; Besch, H J; Walenta, Albert H; Amenitsch, H; Bernstorff, S

    2000-01-01

    In this work a combination of an ionization chamber with one-dimensional spatial resolution and a MicroCAT structure will be presented. Initially, MicroCAT was thought of as a shielding grid (Frisch-grid) but later was used as an active electron amplification device that enables single X-ray photon resolution measurements at low fluxes even with integrating readout electronics. Moreover, the adjustable gas gain that continuously covers the entire range from pure ionization chamber mode up to high gas gains (30000 and more) provides stable operation yielding a huge dynamic range of about 10 sup 8 and more. First measurements on biological samples using small angle X-ray scattering techniques with synchrotron radiation will be presented.

  13. Gas gain operations with single photon resolution using an integrating ionization chamber in small-angle X-ray scattering experiments

    Energy Technology Data Exchange (ETDEWEB)

    Menk, R.H. E-mail: ralf.menk@elettra.trieste.it; Sarvestani, A. E-mail: sarvestani@alwa02.physik.uni-siegen.de; Besch, H.J.; Walenta, A.H.; Amenitsch, H.; Bernstorff, S

    2000-01-21

    In this work a combination of an ionization chamber with one-dimensional spatial resolution and a MicroCAT structure will be presented. Initially, MicroCAT was thought of as a shielding grid (Frisch-grid) but later was used as an active electron amplification device that enables single X-ray photon resolution measurements at low fluxes even with integrating readout electronics. Moreover, the adjustable gas gain that continuously covers the entire range from pure ionization chamber mode up to high gas gains (30000 and more) provides stable operation yielding a huge dynamic range of about 10{sup 8} and more. First measurements on biological samples using small angle X-ray scattering techniques with synchrotron radiation will be presented.

  14. Gas gain operations with single photon resolution using an integrating ionization chamber in small-angle X-ray scattering experiments

    Science.gov (United States)

    Menk, R. H.; Sarvestani, A.; Besch, H. J.; Walenta, A. H.; Amenitsch, H.; Bernstorff, S.

    2000-01-01

    In this work a combination of an ionization chamber with one-dimensional spatial resolution and a MicroCAT structure will be presented. Initially, MicroCAT was thought of as a shielding grid (Frisch-grid) but later was used as an active electron amplification device that enables single X-ray photon resolution measurements at low fluxes even with integrating readout electronics. Moreover, the adjustable gas gain that continuously covers the entire range from pure ionization chamber mode up to high gas gains (30 000 and more) provides stable operation yielding a huge dynamic range of about 10 8 and more. First measurements on biological samples using small angle X-ray scattering techniques with synchrotron radiation will be presented.

  15. A point-focusing small angle x-ray scattering camera using a doubly curved monochromator of a W/Si multilayer

    Science.gov (United States)

    Sasanuma, Yuji; Law, Robert V.; Kobayashi, Yuji

    1996-03-01

    A point-focusing small angle x-ray scattering (SAXS) camera using a doubly curved monochromator of a W/Si multilayer has been designed, constructed, and tested. The two radii of curvature of the monochromator are 20 400 and 7.6 mm. The reflectivity of its first-order Bragg reflection for CuKα radiation was calculated to be 0.82, being comparable to that (0.81) of its total reflection. By only 10 s x-ray exposure, scattering from a high-density polyethylene film was detected on an imaging plate (IP). A rotating-anode x-ray generator operated at 40 kV and 30 mA was used. Diffraction from rat-tail collagen has shown that the optical arrangement gives the Bragg spacing up to, at least, 30 nm for CuKα radiation. Combined with IPs, the camera may permit us to carry out time-resolved SAXS measurements for phase behaviors of liquid crystals, lipids, polymer alloys, etc., on conventional x-ray generators available in laboratories.

  16. Structural characterization of the phospholipid stabilizer layer at the solid-liquid interface of dispersed triglyceride nanocrystals with small-angle x-ray and neutron scattering

    Science.gov (United States)

    Schmiele, Martin; Schindler, Torben; Unruh, Tobias; Busch, Sebastian; Morhenn, Humphrey; Westermann, Martin; Steiniger, Frank; Radulescu, Aurel; Lindner, Peter; Schweins, Ralf; Boesecke, Peter

    2013-06-01

    Dispersions of crystalline nanoparticles with at least one sufficiently large unit cell dimension can give rise to Bragg reflections in the small-angle scattering range. If the nanocrystals possess only a small number of unit cells along these particular crystallographic directions, the corresponding Bragg reflections will be broadened. In a previous study of phospholipid stabilized dispersions of β-tripalmitin platelets [Unruh, J. Appl. Crystallogr.JACGAR0021-889810.1107/S0021889807044378 40, 1008 (2007)], the x-ray powder pattern simulation analysis (XPPSA) was developed. The XPPSA method facilitates the interpretation of the rather complicated small-angle x-ray scattering (SAXS) curves of such dispersions of nanocrystals. The XPPSA method yields the distribution function of the platelet thicknesses and facilitates a structural characterization of the phospholipid stabilizer layer at the solid-liquid interface between the nanocrystals and the dispersion medium from the shape of the broadened 001 Bragg reflection. In this contribution an improved and extended version of the XPPSA method is presented. The SAXS and small-angle neutron scattering patterns of dilute phospholipid stabilized tripalmitin dispersions can be reproduced on the basis of a consistent simulation model for the particles and their phospholipid stabilizer layer on an absolute scale. The results indicate a surprisingly flat arrangement of the phospholipid molecules in the stabilizer layer with a total thickness of only 12 Å. The stabilizer layer can be modeled by an inner shell for the fatty acid chains and an outer shell including the head groups and additional water. The experiments support a dense packing of the phospholipid molecules on the nanocrystal surfaces rather than isolated phospholipid domains.

  17. A new look at Anomalous X-ray Pulsars

    CERN Document Server

    Bisnovatyi-Kogan, G S

    2014-01-01

    We explore a possibility to explain the phenomenon of the Anomalous X-ray Pulsars (AXP) and Soft Gamma-ray Repeaters (SGR) within the scenario of fall-back magnetic accretion onto a young isolated neutron star. The X-ray emission of the pulsar in this case is originated due to accretion of matter onto the surface of the neutron star from the magnetic slab surrounding its magnetosphere. The expected spin-down rate of the neutron star within this approach is close to the observed value. We show that these neutron stars are relatively young and are going through a transition from the propeller state to the accretor state. The pulsars activity in the gamma-rays is connected with their relative youth and is provided by the energy stored in the non-equilibrium layer located in the crust of low-mass neutron stars. This energy can be released due to mixing of matter in the neutron star crust with super heavy nuclei approaching its surface and getting unstable. The nuclei fission in the low-density region initiates ch...

  18. Period clustering of the anomalous X-ray pulsars

    CERN Document Server

    Bisnovatyi-Kogan, G S

    2014-01-01

    In this paper we address the question of why the observed periods of the Anomalous X-ray Pulsars (AXPs) and Soft Gamma-ray Repeaters (SGRs) are clustered in the range 2-12s. We explore a possibility to answer this question assuming that AXPs and SGRs are the descendants of High Mass X-ray Binaries (HMXBs) which have been disintegrated in the core-collapse supernova explosion. The spin period of neutron stars in HMXBs evolves towards the equilibrium period, P_eq. For a wide range of relevant accretion parameters, its value falls in the interval of observed periods of AXPs and SGRs. After the explosion of its massive companion, the neutron star turns out to be embedded into a dense gaseous envelope, the accretion from which leads to the formation of a residual magnetically levitating (ML) disk. We show that the expected mass of a disk in this case is 10^-7 - 10^-8 M_sun which is sufficient to maintain the process of accretion at the rate 10^14 - 10^15 g/s over a time span of a few thousand years. During this pe...

  19. Small-angle and wide-angle X-ray scattering study on the bilayer structure of synthetic and bovine heart cardiolipins

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroshi [Biophysics Laboratory, Department of Chemistry and Chemical Biology, Gunma University, Maebashi, Gunma, 371-8510 (Japan); Hayakawa, Tomohiro [Life Science Laboratory, Advanced Materials Laboratories, Sony Corporation, Yushima, Bunkyo-ku, Tokyo, 113-8510 (Japan); Ito, Kazuki; Takata, Masaki [Structural Materials Science Laboratory, RIKEN SPring-8 Center, Sayo, Hyogo 679-5148 (Japan); Kobayashi, Toshihide, E-mail: htakahas@chem-bio.gunma-u.ac.j [Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198 (Japan)

    2010-10-01

    Cardiolipin (CL) is a membrane phospholipid containing four fatty acid chains. CL plays an important role in energy transformation in mitochondria. The disorder of CL biosynthesis is involved in a genetic disease, Barth syndrome. Alteration of fatty acid composition of CLs has been found in Barth syndrome patients, i.e., the decrease of unsaturated fatty acid chains. In this study, we investigated how the degree of saturation alters the structure of CL bilayers by using X-ray scattering. Bovine heart CL and two synthetic CLs were compared. Fatty acid compositions of these three CLs have different saturation. Small-angle X-ray scattering data showed that the decrease of the number of double bonds in the unsaturated fatty acid chains causes to thicken the CL bilayers. In addition, wide-angle X-ray scattering data suggested that the decrease reduces the degree of disorder of the hydrophobic region in a liquid crystalline phase. These results may be related to the dysfunction of mitochondria in Barth syndrome.

  20. Small-angle and wide-angle X-ray scattering study on the bilayer structure of synthetic and bovine heart cardiolipins

    International Nuclear Information System (INIS)

    Cardiolipin (CL) is a membrane phospholipid containing four fatty acid chains. CL plays an important role in energy transformation in mitochondria. The disorder of CL biosynthesis is involved in a genetic disease, Barth syndrome. Alteration of fatty acid composition of CLs has been found in Barth syndrome patients, i.e., the decrease of unsaturated fatty acid chains. In this study, we investigated how the degree of saturation alters the structure of CL bilayers by using X-ray scattering. Bovine heart CL and two synthetic CLs were compared. Fatty acid compositions of these three CLs have different saturation. Small-angle X-ray scattering data showed that the decrease of the number of double bonds in the unsaturated fatty acid chains causes to thicken the CL bilayers. In addition, wide-angle X-ray scattering data suggested that the decrease reduces the degree of disorder of the hydrophobic region in a liquid crystalline phase. These results may be related to the dysfunction of mitochondria in Barth syndrome.

  1. In Operando Monitoring of the Pore Dynamics in Ordered Mesoporous Electrode Materials by Small Angle X-ray Scattering.

    Science.gov (United States)

    Park, Gwi Ok; Yoon, Jeongbae; Park, Eunjun; Park, Su Bin; Kim, Hyunchul; Kim, Kyoung Ho; Jin, Xing; Shin, Tae Joo; Kim, Hansu; Yoon, Won-Sub; Kim, Ji Man

    2015-05-26

    To monitor dynamic volume changes of electrode materials during electrochemical lithium storage and removal process is of utmost importance for developing high performance lithium storage materials. We herein report an in operando probing of mesoscopic structural changes in ordered mesoporous electrode materials during cycling with synchrotron-based small angel X-ray scattering (SAXS) technique. In operando SAXS studies combined with electrochemical and other physical characterizations straightforwardly show how porous electrode materials underwent volume changes during the whole process of charge and discharge, with respect to their own reaction mechanism with lithium. This comprehensive information on the pore dynamics as well as volume changes of the electrode materials will not only be critical in further understanding of lithium ion storage reaction mechanism of materials, but also enable the innovative design of high performance nanostructured materials for next generation batteries. PMID:25869353

  2. Small-Angle X-ray Scattering Demonstrates Similar Nanostructure in Cortical Bone from Young Adult Animals of Different Species.

    Science.gov (United States)

    Kaspersen, Jørn Døvling; Turunen, Mikael Juhani; Mathavan, Neashan; Lages, Sebastian; Pedersen, Jan Skov; Olsson, Ulf; Isaksson, Hanna

    2016-07-01

    Despite the vast amount of studies focusing on bone nanostructure that have been performed for several decades, doubts regarding the detailed structure of the constituting hydroxyapatite crystal still exist. Different experimental techniques report somewhat different sizes and locations, possibly due to different requirements for the sample preparation. In this study, small- and wide-angle X-ray scattering is used to investigate the nanostructure of femur samples from young adult ovine, bovine, porcine, and murine cortical bone, including three different orthogonal directions relative to the long axis of the bone. The radially averaged scattering from all samples reveals a remarkable similarity in the entire q range, which indicates that the nanostructure is essentially the same in all species. Small differences in the data from different directions confirm that the crystals are elongated in the [001] direction and that this direction is parallel to the long axis of the bone. A model consisting of thin plates is successfully employed to describe the scattering and extract the plate thicknesses, which are found to be in the range of 20-40 Å for most samples but 40-60 Å for the cow samples. It is demonstrated that the mineral plates have a large degree of polydispersity in plate thickness. Additionally, and equally importantly, the scattering data and the model are critically evaluated in terms of model uncertainties and overall information content. PMID:26914607

  3. Investigation of the topological shape of bovine serum albumin in solution by small-angle x-ray scattering at Beijing synchrotron radiation facility

    International Nuclear Information System (INIS)

    This paper reports that at a newly constructed small-angle x-ray scattering station of Beijing Synchrotron Radiation Facility, the topological shape of ligand-free bovine serum albumin in solution has been investigated. An appropriate scattering curve is obtained and the calculated value of the gyration radius is 31.2ű0.25A (1Å=0.1 nm) which is coincident with other ones' results. It finds that the low-resolution structure models obtained by making use of ab initio reconstruction methods are fitting the crystal structure of human serum albumin very well. All of these results perform the potential of the beamline to apply to structural biology studies. The characteristics, the defects, and the improving measures of the station in future are also discussed. (condensed matter: structure, thermal and mechanical properties)

  4. Solution properties of a hydrophobically associating polyacrylamide and its polyelectrolyte derivatives determined by Light Scattering, Small Angle X-ray Scattering and viscometry

    Energy Technology Data Exchange (ETDEWEB)

    Maia, Ana M.S.; Vidal, Rosangela R.L.; Balaban, Rosangela C., E-mail: balaban@supercabo.com.b [Universidade Federal do Rio Grande do Norte (LAPET/DQ/UFRN), Natal, RN (Brazil). Dept. de Quimica. Lab. de Pesquisa em Petroleo; Villetti, Marcos A. [Universidade Federal de Santa Maria (DF/UFSM), RS (Brazil). Dept. de Fisica; Borsali, Redouane [Universite Bordeaux 1, Pessac Cedex (France)

    2011-07-01

    A hydrophobically-modified polyacrylamide and two partially hydrolyzed derivatives containing hydrophobic and carboxylic groups were prepared by micellar polymerization and post hydrolysis. The molecular weight, second virial coefficient and radius of gyration were determined by static light scattering (SLS). Dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) were employed to determine the aggregate formation and type of chain packing in the semidilute regime, respectively. The behavior of solutions in dilute and semidilute regimes was also studied by viscometry and rheology. The hydrophobically-modified polyacrylamide showed a tendency to form aggregates due to the hydrophobic groups, but not enough to increase apparent viscosity. The partially hydrolyzed derivatives did not show the same aggregate-forming tendency. Rather, they exhibited anisotropic behavior, due to the charge density introduced into the polymer chain, which led to a more elongated macromolecular conformation and higher viscosity. (author)

  5. Weak self-interactions of globular proteins studied by small-angle X-ray scattering and structure-based modeling

    CERN Document Server

    Kaieda, Shuji; Plivelic, Tomás S; Halle, Bertil

    2014-01-01

    We investigate protein-protein interactions in solution by small-angle X-ray scattering (SAXS) and theoretical modeling. The structure factor for solutions of bovine pancreatic trypsin inhibitor (BPTI), myoglobin (Mb), and intestinal fatty acid-binding protein (IFABP) is determined from SAXS measurements at multiple concentrations, from Monte Carlo simulations with a coarse-grained structure-based interaction model, and from analytic approximate solutions of two idealized colloidal interaction models without adjustable parameters. By combining these approaches, we find that the structure factor is essentially determined by hard-core and screened electrostatic interactions. Other soft short-ranged interactions (van der Waals and solvation-related) are either individually insignificant or tend to cancel out. The structure factor is also not significantly affected by charge fluctuations. For Mb and IFABP, with small net charge and relatively symmetric charge distribution, the structure factor is well described b...

  6. In-Situ Small-Angle X-Ray Scattering Study of Simple Shear Oriented Poly(ethylene Terephthalate) during Heating

    Science.gov (United States)

    Wang, Zhigang; Xia, Zhiyong; Hsiao, Benjamin; Sue, Hj; Han, Charles

    2002-03-01

    An equal channel angular extrusion (ECAE) process was used to prepare poly(ethylene terephthalate) samples with segmental lamellar orientations. In-situ small-angle X-ray scattering measurements were carried out to follow the structure changes during heating of sections of equal-channel-angular-extruded PET samples before and after the transition line. The total scattering power, fractions of anisotropic and isotropic scattering, orientation factors and long periods along the flow directions were obtained. The changes in these parameters revealed the processes of lamellar relaxation, recrystallization and melting during heating in specimens of different orientation and morphology. Acknowledgements. The financial support of this work is provided by a grant from NIST and NSF (DMR 0098104). The Advanced Polymers Beamline is supported by DOE (DE-FG02-99ER 45760).

  7. Effects of detergents on the oligomeric structures of hemolytic lectin CEL-III as determined by small-angle X-ray scattering.

    Science.gov (United States)

    Goda, Shuichiro; Sadakata, Hitoshi; Unno, Hideaki; Hatakeyama, Tomomitsu

    2013-01-01

    Hemolytic lectin CEL-III isolated from the sea cucumber Cucumaria echinata forms transmembrane pores by self-oligomerization in target cell membranes. It also formed soluble oligomers in aqueous solution upon binding with specific carbohydrates under conditions of high pH and a high salt concentration. The size of the soluble CEL-III oligomers decreased when treated with detergents such as Triton X-100 and SDS. Small-angle X-ray scattering measurements suggested that the dissociated unit of the oligomer was a tightly associated CEL-III heptamer. Without detergents in solution, these heptamers further assembled into larger 21mer oligomers, comprising three heptamers held together by relatively weak hydrophobic interactions. PMID:23470749

  8. Guanosine Quadruplexes in Solution: A Small-Angle X-Ray Scattering Analysis of Temperature Effects on Self-Assembling of Deoxyguanosine Monophosphate

    Directory of Open Access Journals (Sweden)

    P. Mariani

    2010-01-01

    Full Text Available We investigated quadruplex formation in aqueous solutions of 2′-deoxyriboguanosine 5′-monophosphate, d(pG, which takes place in the absence of the covalent axial backbone. A series of in-solution small angle X-ray scattering experiments on d(pG have been performed as a function of temperature in the absence of excess salt, at a concentration just above the critical one at which self-assembling occurs. A global fit approach has been used to derive composition and size distribution of the scattering particles as a function of temperature. The obtained results give thermodynamical justification for the observed phase-behavior, indicating that octamer formation is essential for quadruplex elongation. Our investigation shows that d(pG quadruplexes are very suitable to assess the potential of G-quadruplex formation and to study the self-assembling thermodynamics.

  9. Note: Comparison of grazing incidence small angle x-ray scattering of a titania sponge structure at the beamlines BW4 (DORIS III) and P03 (PETRA III)

    Energy Technology Data Exchange (ETDEWEB)

    Rawolle, M.; Koerstgens, V.; Ruderer, M. A.; Metwalli, E.; Guo, S.; Mueller-Buschbaum, P. [Lehrstuhl fuer Funktionelle Materialien, Physik-Department, Technische Universitaet Muenchen, James-Franck-Str. 1, 85748 Garching (Germany); Herzog, G.; Benecke, G.; Schwartzkopf, M.; Buffet, A.; Perlich, J.; Roth, S. V. [HASYLAB at DESY, Notkestr. 85, 22607 Hamburg (Germany)

    2012-10-15

    Grazing incidence small angle x-ray scattering (GISAXS) is a powerful technique for morphology investigation of nanostructured thin films. GISAXS measurements at the newly installed P03 beamline at the storage ring PETRA III in Hamburg, Germany, are compared to the GISAXS data from the beamline BW4 at the storage ring DORIS III, which had been used extensively for GISAXS investigations in the past. As an example, a titania thin film sponge structure is investigated. Compared to BW4, at beamline P03 the resolution of larger structures is slightly improved and a higher incident flux leads to a factor of 750 in scattered intensity. Therefore, the acquisition time in GISAXS geometry is reduced significantly at beamline P03.

  10. BioXTAS RAW, a software program for high-throughput automated small-angle X-ray scattering data reduction and preliminary analysis

    DEFF Research Database (Denmark)

    Nielsen, S.S.; Toft, K.N.; Snakenborg, Detlef;

    2009-01-01

    A fully open source software program for automated two-dimensional and one-dimensional data reduction and preliminary analysis of isotropic small-angle X-ray scattering (SAXS) data is presented. The program is freely distributed, following the open-source philosophy, and does not rely on any...... commercial software packages. BioXTAS RAW is a fully automated program that, via an online feature, reads raw two-dimensional SAXS detector output files and processes and plots data as the data files are created during measurement sessions. The software handles all steps in the data reduction. This includes......-format input files and is currently compatible with one-dimensional data files from SAXS beamlines at a number of synchrotron facilities. BioXTAS RAW is written in Python with C++ extensions....

  11. Solution small-angle x-ray scattering as a screening and predictive tool in the fabrication of asymmetric block copolymer membranes

    KAUST Repository

    Dorin, Rachel Mika

    2012-05-15

    Small-angle X-ray scattering (SAXS) analysis of the diblock copolymer poly(styrene-b-(4-vinyl)pyridine) in a ternary solvent system of 1,4-dioxane, tetrahydrofuran, and N,N-dimethylformamide, and the triblock terpolymer poly(isoprene-b-styrene-b-(4-vinyl)-pyridine) in a binary solvent system of 1,4-dioxane and tetrahydrofuran, reveals a concentration-dependent onset of ordered structure formation. Asymmetric membranes fabricated from casting solutions with polymer concentrations at or slightly below this ordering concentration possess selective layers with the desired nanostructure. In addition to rapidly screening possible polymer solution concentrations, solution SAXS analysis also predicts hexagonal and square pore lattices of the final membrane surface structure. These results suggest solution SAXS as a powerful tool for screening casting solution concentrations and predicting surface structure in the fabrication of asymmetric ultrafiltration membranes from self-assembled block copolymers. (Figure presented) © 2012 American Chemical Society.

  12. Variation of long periodicity in blends of styrene butadiene, styrene copolymer/polyaniline using small angle X-ray scattering data

    Indian Academy of Sciences (India)

    B G Soares; Fernando G Souza Jr; A Manjunath; H Somashekarappa; R Somashekar; Siddaramaiah

    2007-09-01

    Small angle X-ray scattering data have been recorded for the blends of styrene butadiene, styrene copolymer/polyaniline using the beamline of the LNLS (Laboratorio Nacional de Luz sincroton-Campinas, Brazil). Employing one-dimensional Hosemann's paracrystalline model, we have simulated the meridional reflections of these blends in order to compute the long periodicity and hence to find the variation with concentrations of the blends. Within the region of available experimental data we observe that there is a linear relationship between long periodicity and concentration of blends. These parameters are compared with physical measurements like tensile strength to find the structure–property relation in these blends.

  13. In situ study of the state of lysozyme molecules at the very early stage of the crystallization process by small-angle X-ray scattering

    Science.gov (United States)

    Marchenkova, M. A.; Volkov, V. V.; Blagov, A. E.; Dyakova, Yu. A.; Ilina, K. B.; Tereschenko, E. Yu.; Timofeev, V. I.; Pisarevsky, Yu. V.; Kovalchuk, M. V.

    2016-01-01

    The molecular state of hen egg white lysozyme in solution has been studied by small-angle X-ray scattering (SAXS) combined with molecular simulation. The addition of a precipitant is shown to change the state of the protein molecules in solution. The SAXS data were processed using the constructed models of different oligomers. Under the crystallization conditions, lysozyme is shown to be present in solution as monomers (96.0%), dimers (1.9%), and octamers (2.1%), whereas tetramers and hexamers are not found. The modeled structure of the octamer is not consistent with the commonly accepted unit cell containing eight lysozyme molecules. Meanwhile, the modeled octamers are well-fitted to the crystal structure and can serve as building blocks in the course of crystal growth.

  14. Growth Kinetics of Nanocrystals and Nanorods by Employing Small-angle. X-ray Scattering (SAXS) and Other Techniques

    Institute of Scientific and Technical Information of China (English)

    Kanishka BISWAS; Neenu VARGHESE; C.N.R.Rao

    2008-01-01

    In this article, we report the results of our detailed investigations of the growth kinetics of zero-dimensional nanocrystals as well as one-dimensional nanorods by the combined use of small angel X-ray scattering (SAXS), transmissipon electron microscopy (TEM) along with other physical techniques. The study includes growth kinetics of gold nanocrystals formed by the reduction of HAuCl4 by tetrakis(hydroxymethyl) phosphonium chloride in aqueous solution, of CdSe nanocrystals formed by the reaction of cadmium stearate and selenium under solvothermal conditions, and of ZnO nanorods formed by the reaction of zinc acetate with sodium hydroxide under solvothermal conditions in the absence and presence of capping agents. The growth of gold nanocrystals does not follow the diffusion-limited Ostwald ripening, and instead follows a Sigmoidal rate curve. The heat change associated with the growth determined by isothermal titration calorimetry is about 10 kcal·mol-1 per 1 nm increase in the diameter of the nanocrystals. In the case of CdSe nanocrystals also, the growth mechanism deviates from diffusion-limited growth and follows a combined model containing both diffusion and surface reaction terms. Our study of the growth kinetics of uncapped and poly(vinyl pyrollidone) (PVP)-capped ZnO nanorods has yielded interesting insights. We observe small nanocrystals next to the ZnO nanorods after a lapse of time in addition to periodic focusing and defocusing of the width of the length distribution. These observations lend support to the diffusion-limited growth model for the growth of uncapped ZnO nanorods. Accordingly, the time dependence on the length of uncapped nanorods follows the L3 law as required for diffusion-limited Ostwald ripening. The PVP-capped nanorods, however, show a time dependence, which is best described by a combination of diffusion (L3) and surface reaction (L2) terms.

  15. Crystal Structures and Small-angle X-ray Scattering Analysis of UDP-galactopyranose Mutase from the Pathogenic Fungus Aspergillus fumigatus

    Energy Technology Data Exchange (ETDEWEB)

    Dhatwalia, Richa; Singh, Harkewal; Oppenheimer, Michelle; Karr, Dale B.; Nix, Jay C.; Sobrado, Pablo; Tanner, John J. (LBNL); (Missouri); (VPI)

    2015-10-15

    UDP-galactopyranose mutase (UGM) is a flavoenzyme that catalyzes the conversion of UDP-galactopyranose to UDP-galactofuranose, which is a central reaction in galactofuranose biosynthesis. Galactofuranose has never been found in humans but is an essential building block of the cell wall and extracellular matrix of many bacteria, fungi, and protozoa. The importance of UGM for the viability of many pathogens and its absence in humans make UGM a potential drug target. Here we report the first crystal structures and small-angle x-ray scattering data for UGM from the fungus Aspergillus fumigatus, the causative agent of aspergillosis. The structures reveal that Aspergillus UGM has several extra secondary and tertiary structural elements that are not found in bacterial UGMs yet are important for substrate recognition and oligomerization. Small-angle x-ray scattering data show that Aspergillus UGM forms a tetramer in solution, which is unprecedented for UGMs. The binding of UDP or the substrate induces profound conformational changes in the enzyme. Two loops on opposite sides of the active site move toward each other by over 10 {angstrom} to cover the substrate and create a closed active site. The degree of substrate-induced conformational change exceeds that of bacterial UGMs and is a direct consequence of the unique quaternary structure of Aspergillus UGM. Galactopyranose binds at the re face of the FAD isoalloxazine with the anomeric carbon atom poised for nucleophilic attack by the FAD N5 atom. The structural data provide new insight into substrate recognition and the catalytic mechanism and thus will aid inhibitor design.

  16. Magnetic-field-dependent assembly of silica-coated magnetite nanoclusters probed by Ultra-Small-Angle X-ray Scattering (USAXS)

    Energy Technology Data Exchange (ETDEWEB)

    Malik, Vikash [Physics Department, University of Wisconsin Milwaukee, 1900 E. Kenwood Blvd., Milwaukee, WI 53211 (United States); Suthar, Kamleshkumar J. [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States); Mancini, Derrick C. [Physical Sciences and Engineering, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States); Ilavsky, Jan, E-mail: ilavsky@aps.anl.gov [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States)

    2014-03-15

    Colloidal suspension of the silica coated magnetic nanoclusters (MNCs) was used to study the magnetic field mediated assembly of magnetic nanoparticles. The spatial arrangement of these MNCs in colloidal suspension was studied using the ultra-small-angle X-ray scattering (USAXS) technique with magnetic field applied in directions orthogonal and parallel to the scattering vector. In situ magnetic field analysis of the USAXS scattering measurement showed anisotropic behavior that can be attributed to the formation of colloidal crystals. During magnetization, the clustered magnetic core induces a large dipole moment, and the thickness of the silica shell helps keep distance between the neighboring particles. The assembly of these hybrid nanostructured particles was found to be dependent on the strength and orientation of this external magnetic field. The dipolar chains formed of MNCs arranged themselves into colloidal crystals formed by two-dimensional magnetic sheets. The structure factor calculations suggested that the lattice parameters of these colloidal crystals can be tuned by changing the strength of the external magnetic field. These experiments shed light on the stimuli-responsive assembly of magnetic colloidal nanoparticles that leads to the creation of tunable photonic crystals. - Highlights: • In situ analysis of Magnetically tunable colloidal nanocluster using Ultra Small Angle X-ray Scattering (USAXS) under uniform magnetic field. • The colloidal super-lattice structure was analyzed in magnetic field along the direction parallel and perpendicular to scattering vector. • Structure factors were extracted by subtracting form factor from the USAXS data using Irena software tool. • The observed super-lattice structural spacing can be tuned by extent of the strength of external magnetic field. • The structure factor calculations showed that the colloidal crystal has the hexagonal packing.

  17. An Optimized Table-Top Small-Angle X-ray Scattering Set-up for the Nanoscale Structural Analysis of Soft Matter

    KAUST Repository

    Sibillano, T.

    2014-11-10

    The paper shows how a table top superbright microfocus laboratory X-ray source and an innovative restoring-data algorithm, used in combination, allow to analyze the super molecular structure of soft matter by means of Small Angle X-ray Scattering ex-situ experiments. The proposed theoretical approach is aimed to restore diffraction features from SAXS profiles collected from low scattering biomaterials or soft tissues, and therefore to deal with extremely noisy diffraction SAXS profiles/maps. As biological test cases we inspected: i) residues of exosomes\\' drops from healthy epithelial colon cell line and colorectal cancer cells; ii) collagen/human elastin artificial scaffolds developed for vascular tissue engineering applications; iii) apoferritin protein in solution. Our results show how this combination can provide morphological/structural nanoscale information to characterize new artificial biomaterials and/or to get insight into the transition between healthy and pathological tissues during the progression of a disease, or to morphologically characterize nanoscale proteins, based on SAXS data collected in a room-sized laboratory.

  18. An Optimized Table-Top Small-Angle X-ray Scattering Set-up for the Nanoscale Structural Analysis of Soft Matter

    Science.gov (United States)

    Sibillano, T.; de Caro, L.; Altamura, D.; Siliqi, D.; Ramella, M.; Boccafoschi, F.; Ciasca, G.; Campi, G.; Tirinato, L.; di Fabrizio, E.; Giannini, C.

    2014-11-01

    The paper shows how a table top superbright microfocus laboratory X-ray source and an innovative restoring-data algorithm, used in combination, allow to analyze the super molecular structure of soft matter by means of Small Angle X-ray Scattering ex-situ experiments. The proposed theoretical approach is aimed to restore diffraction features from SAXS profiles collected from low scattering biomaterials or soft tissues, and therefore to deal with extremely noisy diffraction SAXS profiles/maps. As biological test cases we inspected: i) residues of exosomes' drops from healthy epithelial colon cell line and colorectal cancer cells; ii) collagen/human elastin artificial scaffolds developed for vascular tissue engineering applications; iii) apoferritin protein in solution. Our results show how this combination can provide morphological/structural nanoscale information to characterize new artificial biomaterials and/or to get insight into the transition between healthy and pathological tissues during the progression of a disease, or to morphologically characterize nanoscale proteins, based on SAXS data collected in a room-sized laboratory.

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

    International Nuclear Information System (INIS)

    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 × 106 photons/s at a beam size of 1.2 × 1.2 mm2 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−1 down to 0.009 Å−1 in SAXS configuration and of 0.26 Å−1 up to 5.7 Å−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−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

  20. 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.

  1. On Fossil Disk Models of Anomalous X-Ray Pulsars

    CERN Document Server

    Francischelli, G J

    2002-01-01

    Currently, two competing models are invoked in order to explain the observable properties of Anomalous X-ray Pulsars (AXPs). One model assumes that AXP emission is powered by a strongly magnetized neutron star - i.e., a magnetar. Other groups have postulated that the unusually long spin periods associated with AXPs could, instead, be due to accretion. As there are severe observational constraints on any binary accretion model, fossil disk models have been suggested as a plausible alternative. Here we analyze fossil disk models of AXPs in some detail, and point out some of their inherent inconsistencies. For example, we find that, unless it has an exceptionally high magnetic field strength, a neutron star in a fossil disk cannot be observed as an AXP if the disk opacity is dominated by Kramers' law. However, standard alpha-disk models show that a Kramers opacity must dominate for the case log B > 12, making it unlikely that a fossil disk scenario can successfully produce AXPs. Additionally, we find that in ord...

  2. Understanding the X-ray spectrum of anomalous X-ray pulsars and soft gamma-ray repeaters

    International Nuclear Information System (INIS)

    Hard X-rays above 10 keV are detected from several anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs), and different models have been proposed to explain the physical origin within the frame of either a magnetar model or a fallback disk system. Using data from Suzaku and INTEGRAL, we study the soft and hard X-ray spectra of four AXPs/SGRs: 1RXS J170849−400910, 1E 1547.0−5408, SGR 1806−20 and SGR 0501+4516. It is found that the spectra could be well reproduced by the bulk-motion Comptonization (BMC) process as was first suggested by Trümper et al., showing that the accretion scenario could be compatible with X-ray emission from AXPs/SGRs. Simulated results from the Hard X-ray Modulation Telescope using the BMC model show that the spectra would have discrepancies from the power-law, especially the cutoff at ∼200 keV. Thus future observations will allow researchers to distinguish different models of the hard X-ray emission and will help us understand the nature of AXPs/SGRs. (paper)

  3. A small angle X-ray scattering method to investigate the crack tip in metals. Final report of the Marie Curie individual fellowship project

    International Nuclear Information System (INIS)

    Structural materials, such as ferritic and austenitic steels or aluminium alloys used in the nuclear and aircraft industry, are subjected to external operational loads in different environments. Adopting a damage tolerant design principle, understanding the growth of preexisting or newly formed cracks under these conditions is of prime relevance to prevent extensive crack propagation and failure of the component. Within this framework, the characterization of early stages of the damage processes, as nucleation, growth and coalescence of micro-voids and the evolution of the spatial dislocation distribution (dislocation patterning) is a particularly challenging aspect. It was the objective of the work performed to investigate the damage structure near a crack tip by means of small angle X-ray scattering (SAXS). Pre-cracked fracture mechanics standard specimens from different aluminium alloys and steels were loaded up to different amounts of crack growth. From the crack tip range samples of 100 to 200 μm thickness were prepared and a small region around the crack tip was scanned using a microfocused Synchrotron beam. The SAXS experiments were performed at different Synchrotron sources and equipments with different beam cross section, scan step width and X-ray energy. Additionally, the investigation was completed by other methods like X-ray diffraction, X-ray imaging diffraction technique (MAXIM), transmission electron microscopy, scanning electron microscopy, and positron annihilation spectroscopy. The SAXS intensity pattern shows location-related effects. Potential SAXS parameters to characterize the damage are the integral intensity, a fractal dimension parameter and a value determined from the ratio of the intensity vertical and horizontal to the direction of crack growth. Above all, the last parameter is suitable to depict the damage zone around the crack tip. It is robust and applicable even for a material which exhibits an anisotropic SAXS pattern in the

  4. How Large is an α-Helix? Studies of the Radii of Gyration of Helical Peptides by Small-angle X-ray Scattering and Molecular Dynamics

    International Nuclear Information System (INIS)

    Using synchrotron radiation and the small-angle X-ray scattering technique we have measured the radii of gyration of a series of alanine-based alpha-helix-forming peptides of the composition Ace-(AAKAA)(n)-GY-NH(2), n=2-7, in aqueous solvent at 10(+/-1) degrees C. In contrast to other techniques typically used to study alpha-helices in isolation (such as nuclear magnetic resonance and circular dichroism), small-angle X-ray scattering reports on the global structure of a molecule and, as such, provides complementary information to these other, more sequence-local measuring techniques. The radii of gyration that we measure are, except for the 12-mer, lower than the radii of gyration of ideal alpha-helices or helices with frayed ends of the equivalent sequence-length. For example, the measured radius of gyration of the 37-mer is 14.2(+/-0.6)A, which is to be compared with the radius of gyration of an ideal 37-mer alpha-helix of 17.6A. Attempts are made to analyze the origin of this discrepancy in terms of the analytical Zimm-Bragg-Nagai (ZBN) theory, as well as distributed computing explicit solvent molecular dynamics simulations using two variants of the AMBER force-field. The ZBN theory, which treats helices as cylinders connected by random walk segments, predicts markedly larger radii of gyration than those measured. This is true even when the persistence length of the random walk parts is taken to be extremely short (about one residue). Similarly, the molecular dynamics simulations, at the level of sampling available to us, give inaccurate values of the radii of gyration of the molecules (by overestimating them by around 25% for longer peptides) and/or their helical content. We conclude that even at the short sequences examined here (< or =37 amino acid residues), these alpha-helical peptides behave as fluctuating semi-broken rods rather than straight cylinders with frayed ends.

  5. MgATP-induced conformational changes in the iron protein from Azotobacter vinelandii, as studied by small-angle x-ray scattering.

    Science.gov (United States)

    Chen, L; Gavini, N; Tsuruta, H; Eliezer, D; Burgess, B K; Doniach, S; Hodgson, K O

    1994-02-01

    Small angle x-ray scattering experiments have been carried out on the purified iron proteins of nitrogenase from wild-type Azotobacter vinelandii and from a Nif- mutant strain, A. vinelandii UW91 (which has an A157S mutation). This study was designed to investigate the influence of MgATP and MgADP binding on the protein structure in solution. For the wild-type protein, the binding of MgATP induces a significant conformational change that is observed as a decrease of about 2.0 A in the radius of gyration. In contrast, the binding of MgADP to the wild-type iron protein does not detectably affect the radius of gyration. In the absence of nucleotides, the radius of gyration for the UW91 mutant is indistinguishable from that of the wild-type. However, unlike for the wild-type protein, the radius of gyration of the UW91 iron protein is unaffected by the addition of MgATP. We have previously shown that the UW91 iron protein has a normal [4Fe-4S] cluster and MgATP binding ability but that it is completely blocked for electron transfer and MgATP hydrolysis (Gavini, N., and Burgess, B. K. (1992) J. Biol. Chem. 267, 21179-21186). These x-ray scattering measurements suggest that a conformation different from that of the native state is therefore required for the iron protein to perform electron transfer to the MoFe protein. These results also support the hypothesis that Ala-157 is crucial for the iron protein to establish the electron-transfer-favored conformation induced by MgATP binding. PMID:8106367

  6. DEFORMATION OF SOFT COLLOIDAL CRYSTALLINE STRUCTURE-THEORETICAL CONSIDERATIONS AND EXPERIMENTAL EVIDENCES BY SYNCHROTRON SMALL-ANGLE X-RAY SCATTERING ON TENSILE STRETCHED POLYMERIC LATEX FILM

    Institute of Scientific and Technical Information of China (English)

    Jian-qi Zhang; Yong-feng Men

    2009-01-01

    Films obtained via drying a polymeric latex dispersion are normally colloidal crystalline where latex particles are packed into a face centered cubic (fcc) structure.Different from conventional atomic crystallites or hard sphere colloidal crystallites,the crystalline structure of these films is normally deformable due to the low glass transition temperature of the latex particles.Upon tensile deformation,depending on the drawing direction with respect to the normal of specific crystallographic plane,one observes different crystalline structural changes.Three typical situations where crystallographic c-axis,body diagonal or face diagonal of the fcc structure of the colloidal crystallites being parallel to the stretching direction were investigated.Tilting angle and d-spacing of several crystallographic planes as a function of draw ratio at each situation were derived.Experimental evidences for such relationships were also given by considering in-situ synchrotron small angle X-ray scattering data of a typical latex film during stretching.It turns out that the experimental results are fully in accordance with the mathematical calculations.

  7. Characterization of the shape and line-edge roughness of polymer gratings with grazing incidence small-angle X-ray scattering and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Hyo Seon; Chen, Xuanxuan; Rincon-Delgadillo, Paulina A.; Jiang, Zhang; Strzalka, Joseph; Wang, Jin; Chen, Wei; Gronheid, Roel; de Pablo, Juan J.; Ferrier, Nicola; Doxastakis, Manolis; Nealey, Paul F.

    2016-04-22

    Grazing-incidence small-angle X-ray scattering (GISAXS) is increasingly used for the metrology of substrate-supported nanoscale features and nanostructured films. In the case of line gratings, where long objects are arranged with a nanoscale periodicity perpendicular to the beam, a series of characteristic spots of high-intensity (grating truncation rods, GTRs) are recorded on a two-dimensional detector. The intensity of the GTRs is modulated by the three-dimensional shape and arrangement of the lines. Previous studies aimed to extract an average cross-sectional profile of the gratings, attributing intensity loss at GTRs to sample imperfections. Such imperfections are just as important as the average shape when employing soft polymer gratings which display significant line-edge roughness. Herein are reported a series of GISAXS measurements of polymer line gratings over a range of incident angles. Both an average shape and fluctuations contributing to the intensity in between the GTRs are extracted. The results are critically compared with atomic force microscopy (AFM) measurements, and it is found that the two methods are in good agreement if appropriate corrections for scattering from the substrate (GISAXS) and contributions from the probe shape (AFM) are accounted for.

  8. Long-living intermediates during a lamellar to a diamond-cubic lipid phase transition: a small-angle X-ray scattering investigation.

    Science.gov (United States)

    Angelov, Borislav; Angelova, Angelina; Vainio, Ulla; Garamus, Vasil M; Lesieur, Sylviane; Willumeit, Regine; Couvreur, Patrick

    2009-04-01

    To generate nanostructured vehicles with tunable internal organization, the structural phase behavior of a self-assembled amphiphilic mixture involving poly(ethylene glycol) monooleate (MO-PEG) and glycerol monooleate (MO) is studied in excess aqueous medium by time-resolved small-angle X-ray scattering (SAXS) in the temperature range from 1 to 68 degrees C. The SAXS data indicate miscibility of the two components in lamellar and nonlamellar soft-matter nanostructures. The functionalization of the MO assemblies by a MO-PEG amphiphile, which has a flexible large hydrophilic moiety, appears to hinder the epitaxial growth of a double diamond (D) cubic lattice from the lamellar (L) bilayer structure during the thermal phase transition. The incorporated MO-PEG additive is found to facilitate the formation of structural intermediates. They exhibit greater characteristic spacings and large diffusive scattering in broad temperature and time intervals. Their features are compared with those of swollen long-living intermediates in MO/octylglucoside assemblies. A conclusion can be drawn that long-living intermediate states can be equilibrium stabilized in two- or multicomponent amphiphilic systems. Their role as cubic phase precursors is to smooth the structural distortions arising from curvature mismatch between flat and curved regions. The considered MO-PEG functionalized assemblies may be useful for preparation of sterically stabilized liquid-crystalline nanovehicles for confinement of therapeutic biomolecules. PMID:19708151

  9. Amorphous supramolecular structure of carboxymethyl cellulose in aqueous solution at different pH values as determined by rheology, small angle X-ray and light scattering.

    Science.gov (United States)

    Dogsa, Iztok; Tomšič, Matija; Orehek, Janez; Benigar, Elizabeta; Jamnik, Andrej; Stopar, David

    2014-10-13

    Carboxymethyl cellulose (CMC) is one of the most widely used thickening agents in industry. The combination of small-angle X-ray scattering (SAXS), static and dynamic light scattering, as well as viscosity measurements and microscopy at different pH values was utilized to explore the physicochemical properties of CMC on a scale ranging from individual macromolecules to supramolecular assemblies. The supramolecular structure of CMC was represented as a set of characteristic sample subspaces based on SAXS data utilizing the string-of-beads model. The results indicate that at pH 7.0 individual CMC molecules are approximately uniformly distributed in a supramolecular structure owing to strong intra- and intermolecular repulsive interactions. The structure of CMC is most expanded at the value of pKa, where it has the largest radius of gyration, persistence length, and size of heterogeneous regions. Below pKa the majority of the CMC sample volume belongs to the low density subspaces. Most of CMC molecules, however, reside in a few high density subspaces. Dynamically, supramolecular structure of CMC is composed of fast diffusive relaxation processes embedded in a background of non-diffusive slow relaxation process at high pH and mostly slow relaxation processes at low pH. The rheological properties of CMC at different pH values were directly related to the CMC supramolecular structure in the aqueous environment. PMID:25037380

  10. Protein crowding in solution, frozen and freeze-dried states: small-angle neutron and X-ray scattering study of lysozyme/sorbitol/water systems

    Science.gov (United States)

    Krueger, Susan; Khodadadi, Sheila; Clark, Nicholas; McAuley, Arnold; Cristiglio, Viviana; Theyencheri, Narayanan; Curtis, Joseph; Shalaev, Evgenyi

    2015-03-01

    For effective preservation, proteins are often stored as frozen solutions or in glassy states using a freeze-drying process. However, aggregation is often observed after freeze-thaw or reconstitution of freeze-dried powder and the stability of the protein is no longer assured. In this study, small-angle neutron and X-ray scattering (SANS and SAXS) have been used to investigate changes in protein-protein interaction distances of a model protein/cryoprotectant system of lysozyme/sorbitol/water, under representative pharmaceutical processing conditions. The results demonstrate the utility of SAXS and SANS methods to monitor protein crowding at different stages of freezing and drying. The SANS measurements of solution samples showed at least one protein interaction peak corresponding to an interaction distance of ~ 90 Å. In the frozen state, two protein interaction peaks were observed by SANS with corresponding interaction distances at 40 Å as well as 90 Å. On the other hand, both SAXS and SANS data for freeze-dried samples showed three peaks, suggesting interaction distances ranging from ~ 15 Å to 170 Å. Possible interpretations of these interaction peaks will be discussed, as well as the role of sorbitol as a cryoprotectant during the freezing and drying process.

  11. Structural analysis of the yeast exosome Rrp6p–Rrp47p complex by small-angle X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Dedic, Emil; Seweryn, Paulina; Jonstrup, Anette Thyssen; Flygaard, Rasmus Koch [Centre for mRNP Biogenesis and Metabolism, Gustav Wieds Vej 10c, Aarhus University, DK-8000 Aarhus C (Denmark); Department of Molecular Biology and Genetics, Gustav Wieds Vej 10c, Aarhus University, DK-8000 Aarhus C (Denmark); Fedosova, Natalya U. [Department of Biomedicine, Ole Worms Allé 6, Aarhus University, DK-8000 Aarhus C (Denmark); Hoffmann, Søren Vrønning [Institute for Storage Ring Facilities (ISA), Department of Physics and Astronomy, Ny Munkegade 120, Aarhus University, DK-8000 Aarhus C (Denmark); Boesen, Thomas [Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Gustav Wieds Vej 10c, Aarhus University, DK-8000 Aarhus C (Denmark); Department of Molecular Biology and Genetics, Gustav Wieds Vej 10c, Aarhus University, DK-8000 Aarhus C (Denmark); Brodersen, Ditlev Egeskov, E-mail: deb@mb.au.dk [Centre for mRNP Biogenesis and Metabolism, Gustav Wieds Vej 10c, Aarhus University, DK-8000 Aarhus C (Denmark); Department of Molecular Biology and Genetics, Gustav Wieds Vej 10c, Aarhus University, DK-8000 Aarhus C (Denmark)

    2014-07-18

    Highlights: • We show that S. cerevisiae Rrp6p and Rrp47p stabilise each other in vitro. • We determine molecular envelopes of the Rrp6p–Rrp47p complex by SAXS. • Rrp47p binds at the top of the Rrp6p exonuclease domain. • Rrp47p modulates the activity of Rrp6p on a variety of RNA substrates. • Rrp47p does not affect RNA affinity by Rrp6p. - Abstract: The RNase D-type 3′–5′ exonuclease Rrp6p from Saccharomyces cerevisiae is a nuclear-specific cofactor of the RNA exosome and associates in vivo with Rrp47p (Lrp1p). Here, we show using biochemistry and small-angle X-ray scattering (SAXS) that Rrp6p and Rrp47p associate into a stable, heterodimeric complex with an elongated shape consistent with binding of Rrp47p to the nuclease domain and opposite of the HRDC domain of Rrp6p. Rrp47p reduces the exonucleolytic activity of Rrp6p on both single-stranded and structured RNA substrates without significantly altering the affinity towards RNA or the ability of Rrp6p to degrade RNA secondary structure.

  12. Insights into Surface Interactions between Metal Organic Frameworks and Gases during Transient Adsorption and Diffusion by In-Situ Small Angle X-ray Scattering.

    Science.gov (United States)

    Dumée, Ludovic F; He, Li; Hodgson, Peter; Kong, Lingxue

    2016-01-01

    The fabrication of molecular gas sieving materials with specific affinities for a single gas species and able to store large quantities of materials at a low or atmospheric pressure is desperately required to reduce the adverse effects of coal and oil usage in carbon capture. Fundamental understanding of the dynamic adsorption of gas, the diffusion mechanisms across thin film membranes, and the impact of interfaces play a vital role in developing these materials. In this work, single gas permeation tests across micro-porous membrane materials, based on metal organic framework crystals grown on the surface of carbon nanotubes (ZiF-8@CNT), were performed for the first time in-situ at the Australian Synchrotron on the small angle X-ray scattering beamline in order to reveal molecular sieving mechanisms and gas adsorption within the material. The results show that specific chemi-sorption of CO₂ across the ZiF-8 crystal lattices affected the morphology and unit cell parameters, while the sieving of other noble or noble like gases across the ZiF-8@CNT membranes was found to largely follow Knudsen diffusion. This work demonstrates for the first time a novel and effective technique to assess molecular diffusion at the nano-scale across sub-nano-porous materials by probing molecular flexibility across crystal lattice and single cell units. PMID:27598211

  13. Extracting magnetic cluster size and its distributions in advanced perpendicular recording media with shrinking grain size using small angle x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, Virat; Ikeda, Yoshihiro; Takano, Ken; Terris, Bruce D.; Hellwig, Olav [San Jose Research Center, HGST a Western Digital company, 3403 Yerba Buena Rd., San Jose, California 95135 (United States); Wang, Tianhan [Department of Materials Science and Engineering, Stanford University, Stanford, California 94035 (United States); Stanford Institute for Materials and Energy Science (SIMES), SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Wu, Benny; Graves, Catherine [Stanford Institute for Materials and Energy Science (SIMES), SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94035 (United States); Dürr, Hermann A.; Scherz, Andreas; Stöhr, Jo [Stanford Institute for Materials and Energy Science (SIMES), SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)

    2015-05-18

    We analyze the magnetic cluster size (MCS) and magnetic cluster size distribution (MCSD) in a variety of perpendicular magnetic recording (PMR) media designs using resonant small angle x-ray scattering at the Co L{sub 3} absorption edge. The different PMR media flavors considered here vary in grain size between 7.5 and 9.5 nm as well as in lateral inter-granular exchange strength, which is controlled via the segregant amount. While for high inter-granular exchange, the MCS increases rapidly for grain sizes below 8.5 nm, we show that for increased amount of segregant with less exchange the MCS remains relatively small, even for grain sizes of 7.5 and 8 nm. However, the MCSD still increases sharply when shrinking grains from 8 to 7.5 nm. We show evidence that recording performance such as signal-to-noise-ratio on the spin stand correlates well with the product of magnetic cluster size and magnetic cluster size distribution.

  14. Evolution of Helium with Temperature in Neutron-Irradiated 10B-Doped Aluminum by Small-Angle X-Ray Scattering

    Directory of Open Access Journals (Sweden)

    Chaoqiang Huang

    2014-01-01

    Full Text Available Helium status is the primary effect of material properties under radiation. 10B-doped aluminum samples were prepared via arc melting technique and rapidly cooled with liquid nitrogen to increase the boron concentration during the formation of compounds. An accumulated helium concentration of ~6.2 × 1025 m−3 was obtained via reactor neutron irradiation with the reaction of 10B(n, α7Li. Temperature-stimulated helium evolution was observed via small-angle X-ray scattering (SAXS and was confirmed via transmission electron microscopy (TEM. The SAXS results show that the volume fraction of helium bubbles significantly increased with temperature. The amount of helium bubbles reached its maximum at 600°C, and the most probable diameter of the helium bubbles increased with temperature until 14.6 nm at 700°C. A similar size distribution of helium bubbles was obtained via TEM after in situ SAXS measurement at 700°C, except that the most probable diameter was 3.9 nm smaller.

  15. Small angle X-ray scattering study of poly(N-isopropyl acrylamide) based cryogels near the volume-phase transition temperature

    Energy Technology Data Exchange (ETDEWEB)

    Chalal, Mohand [Laboratoire d' Electronique Quantique, Faculte de Physique, USTHB Alger, 16111 Alger (Algeria); Ehrburger-Dolle, Francoise; Morfin, Isabelle [Laboratoire de Spectrometrie Physique, UMR 5588 CNRS/UJF, 38402 Saint Martin d' Heres (France); Armas, Maria-Rosa Aguilar de; Lopez, Maria-Luisa [Instituto de Ciencia y TecnologIa de PolImeros, CSIC and CIBER-BBN, 28006 Madrid (Spain); Bley, Francoise, E-mail: francoise.ehrburger-dolle@ujf-grenoble.f [Science et Ingenierie des Materiaux et Procedes, UMR 5266 CNRS/INPG/UJF, 38402 Saint Martin d' Heres (France)

    2010-10-01

    The structural modifications induced by changes in temperature are investigated by Small-Angle X-ray Scattering (SAXS) over a broad range of q-values (3.5x10{sup -2} - 12 nm{sup -1}) in cryogels based on N-isopropylacrylamide (NIPA) and/or 2-Hydroxyethyl methacrylate-L-Lactide-Dextran (HEMA-LLA-D) macromer. Various copolymeric cryogels of these two monomers are prepared by cryopolymerization yielding macroporous gels (cryogels). For the plain pNIPA cryogel, the SAXS curves obtained at each temperature are well fitted by a sum of four equations describing respectively the scattering resulting from the gel surface (power law), from the solid-like (Guinier equation) and liquid-like (Ornstein-Zernike equation) heterogeneities and from the chain-chain correlation yielding a broad peak (pseudo-Voigt equation) in the high-q domain. The temperature dependence of the parameters obtained from the fit is analyzed and discussed. It is shown that the existence of an isoscattering (or isosbestic) point observed in pNIPA gels and in some copolymers is related to features observed by Differential Scanning Calorimetry and swelling ratio measurements.

  16. Structural Studies on Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) Malaria Antigens Using Small Angle X-Ray Scattering (SAXS)

    DEFF Research Database (Denmark)

    Christoffersen, Stig

    Infection with the pathogenic Plasmodium falciparum parasite causes the potentially deadly Malaria disease which leads to over 1 million fatalities each year according to the WHO (World Health Organization). Individuals subjected to multiple infections gradually become immune to the disease sympt...... covers many aspects of PfEMP1 structural composition and mechanism. Information that could be of value to future vaccine developments which ultimately will prevent the severe and fatal outcomes that malaria afflicts.......Infection with the pathogenic Plasmodium falciparum parasite causes the potentially deadly Malaria disease which leads to over 1 million fatalities each year according to the WHO (World Health Organization). Individuals subjected to multiple infections gradually become immune to the disease...... for low-resolution structural characterization of the PfEMP1 proteins. This thesis describes how small angle X-ray scattering (SAXS) was used to achieve low-resolution structural information for a range of PfEMP1 proteins investigated as potent malaria antigens. Especially the leading vaccine candidate...

  17. PAMAM6 dendrimers and DNA: pH dependent "beads-on-a-string" behavior revealed by small angle X-ray scattering

    CERN Document Server

    Dootz, Rolf; Pfohl, Thomas

    2011-01-01

    DNA interactions with polycations are not only important for our understanding of chromatin compaction but also for characterizing DNA-binding proteins involved in transcription, replication and repair. DNA is known to form several types of liquid-crystalline phases depending, among other factors, on polycation structure and charge density. Theoretical studies and simulations have predicted the wrapping of DNA around spherical positively charged polycations. As a potential mimic of the histone octamer or other DNA wrapping proteins, poly(amido amine) generation 6 (PAMAM6) dendrimers have been chosen for our study. The self-assembly of DNA induced by PAMAM6 has been investigated using small angle X-ray scattering (SAXS) in order to reveal the assemblies' structure dependence on the pH of the environment and on dendrimers concentration. We demonstrate that at pH 8.5 dense phases are formed and characterized by a 2D-columnar hexagonal lattice which is transformed into a 3D hexagonal lattice with increasing dendr...

  18. Magnetic-field-dependent assembly of silica-coated magnetite nanoclusters probed by Ultra-Small-Angle X-ray Scattering (USAXS)

    Science.gov (United States)

    Malik, Vikash; Suthar, Kamleshkumar J.; Mancini, Derrick C.; Ilavsky, Jan

    2014-03-01

    Colloidal suspension of the silica coated magnetic nanoclusters (MNCs) was used to study the magnetic field mediated assembly of magnetic nanoparticles. The spatial arrangement of these MNCs in colloidal suspension was studied using the ultra-small-angle X-ray scattering (USAXS) technique with magnetic field applied in directions orthogonal and parallel to the scattering vector. In situ magnetic field analysis of the USAXS scattering measurement showed anisotropic behavior that can be attributed to the formation of colloidal crystals. During magnetization, the clustered magnetic core induces a large dipole moment, and the thickness of the silica shell helps keep distance between the neighboring particles. The assembly of these hybrid nanostructured particles was found to be dependent on the strength and orientation of this external magnetic field. The dipolar chains formed of MNCs arranged themselves into colloidal crystals formed by two-dimensional magnetic sheets. The structure factor calculations suggested that the lattice parameters of these colloidal crystals can be tuned by changing the strength of the external magnetic field. These experiments shed light on the stimuli-responsive assembly of magnetic colloidal nanoparticles that leads to the creation of tunable photonic crystals.

  19. Small-angle X-ray scattering reveals compact domain-domain interactions in the N-terminal region of filamin C.

    Directory of Open Access Journals (Sweden)

    Ritika Sethi

    Full Text Available Filamins are multi-domain, actin cross-linking, and scaffolding proteins. In addition to the actin cross-linking function, filamins have a role in mechanosensor signaling. The mechanosensor function is mediated by domain-domain interaction in the C-terminal region of filamins. Recently, we have shown that there is a three-domain interaction module in the N-terminal region of filamins, where the neighboring domains stabilize the structure of the middle domain and thereby regulate its interaction with ligands. In this study, we have used small-angle X-ray scattering as a tool to screen for potential domain-domain interactions in the N-terminal region. We found evidence of four domain-domain interactions with varying flexibility. These results confirm our previous study showing that domains 3, 4, and 5 exist as a compact three domain module. In addition, we report interactions between domains 11-12 and 14-15, which are thus new candidate sites for mechanical regulation.

  20. Insights into Surface Interactions between Metal Organic Frameworks and Gases during Transient Adsorption and Diffusion by In-Situ Small Angle X-ray Scattering

    Science.gov (United States)

    Dumée, Ludovic F.; He, Li; Hodgson, Peter; Kong, Lingxue

    2016-01-01

    The fabrication of molecular gas sieving materials with specific affinities for a single gas species and able to store large quantities of materials at a low or atmospheric pressure is desperately required to reduce the adverse effects of coal and oil usage in carbon capture. Fundamental understanding of the dynamic adsorption of gas, the diffusion mechanisms across thin film membranes, and the impact of interfaces play a vital role in developing these materials. In this work, single gas permeation tests across micro-porous membrane materials, based on metal organic framework crystals grown on the surface of carbon nanotubes (ZiF-8@CNT), were performed for the first time in-situ at the Australian Synchrotron on the small angle X-ray scattering beamline in order to reveal molecular sieving mechanisms and gas adsorption within the material. The results show that specific chemi-sorption of CO2 across the ZiF-8 crystal lattices affected the morphology and unit cell parameters, while the sieving of other noble or noble like gases across the ZiF-8@CNT membranes was found to largely follow Knudsen diffusion. This work demonstrates for the first time a novel and effective technique to assess molecular diffusion at the nano-scale across sub-nano-porous materials by probing molecular flexibility across crystal lattice and single cell units. PMID:27598211

  1. Insights into Surface Interactions between Metal Organic Frameworks and Gases during Transient Adsorption and Diffusion by In-Situ Small Angle X-ray Scattering

    Directory of Open Access Journals (Sweden)

    Ludovic F. Dumée

    2016-09-01

    Full Text Available The fabrication of molecular gas sieving materials with specific affinities for a single gas species and able to store large quantities of materials at a low or atmospheric pressure is desperately required to reduce the adverse effects of coal and oil usage in carbon capture. Fundamental understanding of the dynamic adsorption of gas, the diffusion mechanisms across thin film membranes, and the impact of interfaces play a vital role in developing these materials. In this work, single gas permeation tests across micro-porous membrane materials, based on metal organic framework crystals grown on the surface of carbon nanotubes (ZiF-8@CNT, were performed for the first time in-situ at the Australian Synchrotron on the small angle X-ray scattering beamline in order to reveal molecular sieving mechanisms and gas adsorption within the material. The results show that specific chemi-sorption of CO2 across the ZiF-8 crystal lattices affected the morphology and unit cell parameters, while the sieving of other noble or noble like gases across the ZiF-8@CNT membranes was found to largely follow Knudsen diffusion. This work demonstrates for the first time a novel and effective technique to assess molecular diffusion at the nano-scale across sub-nano-porous materials by probing molecular flexibility across crystal lattice and single cell units.

  2. Characterization of structure and coagulation behaviour of refractory organic substances (ROS) using small-angle neutron scattering (SANS), small-angle x-ray scattering (SAXS) and x-ray microscopy; Charakterisierung von Struktur und Koagulationsverhalten von Refraktaeren Organischen Saeuren (ROS) mit Hilfe von Neutronenkleinwinkelstreuung (SANS), Roentgenkleinwinkelstreuung (SAXS) und Roentgenmikroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Pranzas, P.K. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Werkstofforschung

    1999-07-01

    In this work structure, coagulation and complexation behaviour of aquatic refractory organic substances (ROS) (humic and fulvic acids) were characterized. For this purpose a structural analytical system with the methods small-angle neutron scattering (SANS), small-angle x-ray scattering (SAXS) and X-ray microscopy with synchrotron radiation was developed and established. Size distributions of ROS of different origin were calculated from the scattering curves. Spherical ROS units were obtained, which coagulated by forming chainlike structures or disordered ROS agglomerates at higher concentrations. Additionally the average molecular weights of several ROS were calculated. Studies of the coagulation behaviour of ROS towards copper ions resulted in larger ROS-agglomerates besides the spherical ROS units. A linear relation between the addition of Cu{sup 2+} and the formation of the ROS-Cu{sup 2+}-agglomerates was found. With X-ray microscopy an extensive ROS-Cu{sup 2}-network structure could be registrated. For mercury and cadmium ions such coagulation interactions were not found. Investigations with X-ray microscopy of the coagulation behaviour of ROS towards the cationic surfactant DTB resulted in micel-like structures of equal size, which were spread throughout the solution. With increasing concentrations of DTB larger agglomerates up to network structures were obtained. (orig.) [German] In dieser Arbeit wurden Struktur, Koagulations- und Komplexierungsverhalten von aquatischen refraktaeren organischen Saeuren (ROS) (Humin- und Fulvinsaeuren) charakterisiert. Zu diesem Zweck wurde ein strukturanalytisches Gesamtsystem mit den Methoden Neutronenkleinwinkelstreuung (SANS), Roentgenkleinwinkelstreuung (SAXS) und Roentgenmikroskopie mit Synchrotronstrahlung entwickelt und etabliert. Fuer ROS unterschiedlicher Herkunft in Loesung wurden Groessenverteilungen aus den Streukurven berechnet. Es wurden kugelfoermige ROS-Einheiten gefunden, die bei hoeheren ROS

  3. Evolution and change of He bubbles in He-containing Ti films upon thermal treatment studied by small-angle X-ray scattering and transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Guangai [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); College of Nuclear Science and Technology, University of Science and Technology of China, Hefei, 230029 (China); Wu, Erdong, E-mail: ewu@imr.ac.cn [National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Huang, Chaoqiang [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); College of Nuclear Science and Technology, University of Science and Technology of China, Hefei, 230029 (China); Cheng, Chun [National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Yan, Guanyun [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Wang, Xiaolin [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); College of Nuclear Science and Technology, University of Science and Technology of China, Hefei, 230029 (China); Liu, Shi [National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Tian, Qiang; Chen, Bo [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Wu, Zhonghua [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Liu, Yi; Wang, Jie [Institute of Shanghai Apply Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2014-05-02

    Evolution and change of He bubbles in magnetron sputtering prepared He-containing Ti films under thermal treatment are studied by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and X-ray diffraction. Incorporation of He introduces a large number of He-vacancy clusters and some voids in the films, and significantly increases SAXS intensity and causes anisotropic scattering. The change of He induced defects during annealing is affected by thermal diffusion and migration of trapped He to the surface and between interfaces of He induced defects within the films. Annealing at 200 and 400 °C reduces intensity and anisotropy of SAXS, in accord with observed shrinking and disappearance of the voids. The simultaneous growth of non-uniformly distributed He bubbles to the sizes of 1–2 nm and a population level of 10{sup 5}/μm{sup 3} are detected in the temperature range. The changes are explained by migration and coalescence mechanisms, which requires low apparent activation energy. Inconsistence between TEM and SAXS observations is noted and attributed to thinning induced internal stress relaxation of TEM specimen. Remarkable enlargement of He bubbles, associated with increased SAXS intensity and fractal dimension, is observed after 600 °C annealing, indicating involvement of Ostwald Ripening (OR) mechanism. The OR process dominates at 800 °C, where the high temperature provides activation energy for accelerated He dissociation from small bubbles into larger ones, and generating textured microstructure and agglomerated bubble clusters. The inhomogeneous bubble size distribution observed at this temperature covers a broad range of about 10–50 nm and possessing a population density level of 10{sup 3}/μm{sup 3}. - Highlights: • Change of He bubbles in thermally treated Ti–He films is studied by SAXS and TEM. • SAXS reveals size distribution and fractional population of He bubbles in films. • He-vacancy clusters in Ti–He film

  4. Small-angle X-ray scattering and rheological characterization of alginate gels. 2. Time-resolved studies on ionotropic gels

    Science.gov (United States)

    Yuguchi, Y.; Urakawa, H.; Kajiwara, K.; Draget, K. I.; Stokke, B. T.

    2000-10-01

    Gelation was observed by time-resolved small-angle X-ray scattering and rheology on 10 mg/ml Ca-alginate gels prepared by in situ release of Ca 2+ from CaEGTA or CaCO 3 with total Ca 2+ concentration in the range 10-20 mM. This was carried out for alginates having a fraction of α- L-GulA (G) of FG=0.39 and 0.68, respectively, obtained by the selection of alginates isolated from two different brown algae, Ascophyllum nodosum and Laminaria hyperborea stipe. Correlation between the rheological data and SAXS data shows that a large fraction of the lateral association precedes the formation of a continuous network through the sample cell. Following the initial association of chain segments in junction zones, the analysis using two-component broken rod model indicates the formation of larger bundles, and that the relative weight of these bundles increases with increasing time. The molecular model for the bundles is proposed by associating 2-16 units (G-blocks) composed of 14 (1→4) linked residues of α- L-GulA in parallel according to the available crystallographic data. The storage modulus increases as the bundles composed of associated alginate chains grow during the gel formation. The gel elasticity is mainly sustained by single chains in the alginate sample with a low fraction of α- L-GulA. The alginates with a high fraction of α- L-GulA associate into thicker bundles which join to form a network. Here the gel elasticity seems to be due to the flexible joints between bundles, since the fraction of single chains is extremely low.

  5. Structural model and stability studies of the extracellular domain of the human amyloid precursor protein obtained using small angle X-ray scattering

    International Nuclear Information System (INIS)

    Full text: The amyloid precursor protein (APP) is the precursor of the β-amyloid peptide (Aβ), which is centrally related to the genesis of Alzheimer's disease (AD). In addition, APP has been suggested to mediate and/or participate in events that lead to neuronal degeneration in AD. Human APP exists in various isoforms, of which the major ones contain 695, 751 and 770 aminoacids. Proteolytic cleavage of APP by α- or β-secretases releases the extracellular soluble fragments sAPPα and sAPPβ, respectively. Despite the fact that sAPPα plays important roles in both physiological and pathological processes in the brain, very little is known about the structure and stability of this protein. We have recently presented a structural model of sAPPα695 obtained from small-angle X-ray scattering (SAXS) measurements (Gralle et al., Biophys. J. 83,3513-3524). The elongated shape of the reported model is in agreement with the circular dichroism and secondary structure predictions based on the aminoacid sequence of APP. This suggests that a significant fraction of APP (30% of the aminoacid residues) is not involved in standard secondary structure elements. We now report high resolution SAXS models and studies of folding and stabilities of both sAPPα695 and sAPPα770. These high resolution measurements allows the calculation of models up to subdomain structure (4 angstrom resolution). These models enable the prediction of hydrodynamic parameters of these proteins which can be compared with measured values. SAXS measurements of the denaturation of sAPPα695 and sAPPα770 by GdnHCl and urea revealed a multi-step folding pathway for both sAPPα isoforms. The stepwise denaturation process can be correlated to the three-dimensional models. (author)

  6. Structure factor of blends of solvent-free nanoparticle–organic hybrid materials: density-functional theory and small angle X-ray scattering

    KAUST Repository

    Yu, Hsiu-Yu

    2014-09-15

    © the Partner Organisations 2014. We investigate the static structure factor S(q) of solvent-free nanoparticle-organic hybrid materials consisting of silica nanocores and space-filling polyethylene glycol coronas using a density-functional theory and small angle X-ray scattering measurements. The theory considers a bidisperse suspension of hard spheres with different radii and tethered bead-spring oligomers with different grafting densities to approximate the polydispersity effects in experiments. The experimental systems studied include pure samples with different silica core volume fractions and the associated mean corona grafting densities, and blends with different mixing ratios of the pure samples, in order to introduce varying polydispersity of corona grafting density. Our scattering experiments and theory show that, compared to the hard-sphere suspension with the same core volume fraction, S(q) for pure samples exhibit both substantially smaller values at small q and stronger particle correlations corresponding to a larger effective hard core at large q, indicating that the tethered incompressible oligomers enforce a more uniform particle distribution, and the densely grafted brush gives rise to an additional exclusionary effect between the nanoparticles. According to the theory, polydispersity in the oligomer grafting density controls the deviation of S(q) from the monodisperse system at smaller q, and the interplay of the enhanced effective core size and the entropic attraction among the particles is responsible for complex variations in the particle correlations at larger q. The successful comparison between the predictions and the measurements for the blends further suggests that S(q) can be used to assess the uniformity of grafting density in polymer-grafted nanoparticle materials. This journal is

  7. Combining NMR and small angle X-ray and neutron scattering in the structural analysis of a ternary protein-RNA complex

    Energy Technology Data Exchange (ETDEWEB)

    Hennig, Janosch; Wang, Iren; Sonntag, Miriam [Institute of Structural Biology, Helmholtz Zentrum Muenchen (Germany); Gabel, Frank [Extremophiles and Large Molecular Assemblies Group (ELMA), Institut de Biologie Structurale (IBS) CEA-CNRS-UJF (France); Sattler, Michael, E-mail: sattler@helmholtz-muenchen.de [Institute of Structural Biology, Helmholtz Zentrum Muenchen (Germany)

    2013-05-15

    Many processes in the regulation of gene expression and signaling involve the formation of protein complexes involving multi-domain proteins. Individual domains that mediate protein-protein and protein-nucleic acid interactions are typically connected by flexible linkers, which contribute to conformational dynamics and enable the formation of complexes with distinct binding partners. Solution techniques are therefore required for structural analysis and to characterize potential conformational dynamics. Nuclear magnetic resonance spectroscopy (NMR) provides such information but often only sparse data are obtained with increasing molecular weight of the complexes. It is therefore beneficial to combine NMR data with additional structural restraints from complementary solution techniques. Small angle X-ray/neutron scattering (SAXS/SANS) data can be efficiently combined with NMR-derived information, either for validation or by providing additional restraints for structural analysis. Here, we show that the combination of SAXS and SANS data can help to refine structural models obtained from data-driven docking using HADDOCK based on sparse NMR data. The approach is demonstrated with the ternary protein-protein-RNA complex involving two RNA recognition motif (RRM) domains of Sex-lethal, the N-terminal cold shock domain of Upstream-to-N-Ras, and msl-2 mRNA. Based on chemical shift perturbations we have mapped protein-protein and protein-RNA interfaces and complemented this NMR-derived information with SAXS data, as well as SANS measurements on subunit-selectively deuterated samples of the ternary complex. Our results show that, while the use of SAXS data is beneficial, the additional combination with contrast variation in SANS data resolves remaining ambiguities and improves the docking based on chemical shift perturbations of the ternary protein-RNA complex.

  8. Quantification of void network architectures of suspension plasma-sprayed (SPS) yttria-stabilized zirconia (YSZ) coatings using Ultra-small-angle X-ray scattering (USAXS)

    International Nuclear Information System (INIS)

    Suspension plasma spraying (SPS) is able to process a stabilized suspension of nanometer-sized feedstock particles to form thin (from 20 to 100 μm) coatings with unique microstructures. The void (pore) network structure of these ceramic coatings is challenging to characterize and quantify using commonly used techniques due to small sizes involved. Nevertheless, the discrimination of these pores in terms of their size and shape distribution, anisotropy, specific surface area, etc., is critical for the understanding of processing, microstructure, and properties relationships. We will show that one of suitable combinations of techniques providing sufficient detail is ultra-small-angle X-ray scattering (USAXS) and helium pycnometry, combined with scanning electron microscopy (SEM). Yttria-partially stabilized zirconia (YSZ) coatings were manufactured by plasma processing of suspension of particles with average diameter of ∼50 nm. Several sets of spray parameters (plasma gas mixture, spray distance, electric arc intensity, etc.) were used to generate plasma jets with different mass enthalpies and coefficients of thermal transfer and different heat fluxes transferred to the substrate. Free-standing coatings were studied as-sprayed and annealed at 800 and 1100 deg. C for 10 and 100 h (non-constrained sintering). Results indicate that the SPS coatings exhibit nanosized pore microstructure: average void size was about the same size scale as the feedstock size; i.e., nanometer sizes with multimodal void size distribution. About 80% of the pores (by number) exhibited characteristic dimensions smaller than 30 nm. Total void content of as-sprayed SPS coatings varies between 13% and 20%. Most of the voids were found to be opened with only between one-tenth to one-third of voids volume being inaccessible by intrusion (not connected to either surface). During annealing, even at temperatures as low than 800 deg. C, the microstructure transformed: while the total void content did

  9. Edible oil structures at low and intermediate concentrations. II. Ultra-small angle X-ray scattering of in situ tristearin solids in triolein

    Science.gov (United States)

    Peyronel, Fernanda; Ilavsky, Jan; Mazzanti, Gianfranco; Marangoni, Alejandro G.; Pink, David A.

    2013-12-01

    Ultra-small angle X-ray scattering has been used for the first time to elucidate, in situ, the aggregation structure of a model edible oil system. The three-dimensional nano- to micro-structure of tristearin solid particles in triolein solvent was investigated using 5, 10, 15, and 20% solids. Three different sample preparation procedures were investigated: two slow cooling rates of 0.5°/min, case 1 (22 days of storage at room temperature) and case 2 (no storage), and one fast cooling of 30°/min, case 3 (no storage). The length scale investigated, by using the Bonse-Hart camera at beamline ID-15D at the Advanced Photon Source, Argonne National Laboratory, covered the range from 300 Å to 10 μm. The unified fit and the Guinier-Porod models in the Irena software were used to fit the data. The former was used to fit 3 structural levels. Level 1 structures showed that the primary scatterers were essentially 2-dimensional objects for the three cases. The scatterers possessed lateral dimensions between 1000 and 4300 Å. This is consistent with the sizes of crystalline nanoplatelets present which were observed using cryo-TEM. Level 2 structures were aggregates possessing radii of gyration, Rg2 between 1800 Å and 12000 Å and fractal dimensions of either D2=1 for case 3 or 1.8≤D2≤2.1 for case 1 and case 2. D2 = 1 is consistent with unaggregated 1-dimensional objects. 1.8 ≤ D2 ≤ 2.1 is consistent with these 1-dimensional objects (below) forming structures characteristic of diffusion or reaction limited cluster-cluster aggregation. Level 3 structures showed that the spatial distribution of the level 2 structures was uniform, on the average, for case 1, with fractal dimension D3≈3 while for case 2 and case 3 the fractal dimension was D3≈2.2, which suggested that the large-scale distribution had not come to equilibrium. The Guinier-Porod model showed that the structures giving rise to the aggregates with a fractal dimension given by D2 in the unified fit level 2

  10. Long-Term RXTE Monitoring of Anomalous X-ray Pulsars

    CERN Document Server

    Gavriil, F P; Gavriil, Fotis P.; Kaspi, Victoria M.

    2001-01-01

    We report on the long-term monitoring of three anomalous X-ray pulsars using the Rossi X-ray Timing Explorer (RXTE). We present a phase-coherent timing ephemeris for 4U 0142+61, and show that it has rotated with high stability over 4.4 yr, with RMS phase deviations of 7% of the pulse period from a simple fit including only $\

  11. A Two-Temperature Supernova Fallback Disk Model for Anomalous X-ray Pulsars

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We present a case study of the relevance of the radially pulsational instability of a two-temperature accretion disk around a neutron star to anomalous X-ray pulsars (AXPs). Our estimates are based on the approximation that such a neutron star disk with mass in the range of 10-6 - 10-5 M⊙ is formed by supernova fallback. We derive several peculiar properties of the accretion disk instability: a narrow interval of X-ray pulse periods; lower X-ray luminosities; a period derivative and an evolution time scale. All these results are in good agreement with the observations of the AXPs.

  12. Long-term evolution of anomalous X-ray pulsars and soft gamma repeaters

    OpenAIRE

    Benli, Onur; Ertan, Unal

    2016-01-01

    We have investigated the long-term evolution of individual anomalous X-ray pulsars (AXPs) and soft gamma repeaters (SGRs) with relatively well constrained X-ray luminosity and rotational properties. In the frame of the fallback disc model, we have obtained the ranges of disc mass and dipole field strength that can produce the observed source properties. We have compared our results with those obtained earlier for dim isolated neutron stars (XDINs). Our results show that (1) the X-ray luminosi...

  13. Multimodal particle size distribution or fractal surface of acrylic acid copolymer nanoparticles: A small-angle X-ray scattering study using direct Fourier and indirect maximum entropy methods

    OpenAIRE

    Mueller, J.J.; Hansen, S; Lukowski, G.; Gast, K.

    1995-01-01

    Acrylic acid copolymers are potential carriers for drug delivery. The surface, surface rugosity and the absolute dimension of the particles are parameters that determine the binding of drugs or detergents, diffusion phenomena at the surface and the distribution of the carrier within the human body. The particle-size distribution and surface rugosity of the particles have been investigated by small-angle X-ray scattering and dynamic light scattering. Direct Fourier transform as well as a new s...

  14. A small-angle X-ray scattering study of the effect of chain architecture on the shear-induced crystallization of branched and linear poly(ethylene terephthalate)

    OpenAIRE

    Hanley, T.; Sutton, D.; Heeley, E; Moad, G.; KNOTT, R.

    2007-01-01

    The synchrotron-based small-angle X-ray scattering (SAXS) technique was used to investigate the shear-induced crystallization kinetics of branched/unbranched poly(ethylene terephthalate) (PET). Reactive extrusion of bottle-grade PET with the branching and chain-extension agents pyromellitic dianhydride and pentaerythritol results in enhanced rheological properties, such as higher melt strength and higher viscosity. In this study, six samples of PET were investigated: linear PET [intrinsic vis...

  15. Probing bismuth ferrite nanoparticles by hard x-ray photoemission: Anomalous occurrence of metallic bismuth

    International Nuclear Information System (INIS)

    We have investigated bismuth ferrite nanoparticles (∼75 nm and ∼155 nm) synthesized by a chemical method, using soft X-ray (1253.6 eV) and hard X-ray (3500, 5500, and 7500 eV) photoelectron spectroscopy. This provided an evidence for the variation of chemical state of bismuth in crystalline, phase pure nanoparticles. X-ray photoelectron spectroscopy analysis using Mg Kα (1253.6 eV) source showed that iron and bismuth were present in both Fe3+ and Bi3+ valence states as expected for bismuth ferrite. However, hard X-ray photoelectron spectroscopy analysis of the bismuth ferrite nanoparticles using variable photon energies unexpectedly showed the presence of Bi0 valence state below the surface region, indicating that bismuth ferrite nanoparticles are chemically inhomogeneous in the radial direction. Consistently, small-angle X-ray scattering reveals a core-shell structure for these radial inhomogeneous nanoparticles.

  16. Edible oil structures at low and intermediate concentrations. II. Ultra-small angle X-ray scattering of in situ tristearin solids in triolein

    Energy Technology Data Exchange (ETDEWEB)

    Peyronel, Fernanda; Marangoni, Alejandro G. [Food Science Department, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Ilavsky, Jan [Advanced Photon Source, Argonne National Laboratory, 9700S Cass Ave., Bldg. 434D, Argonne, Illinois 60439 (United States); Mazzanti, Gianfranco [Department of Process Engineering and Applied Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2 (Canada); Pink, David A. [Food Science Department, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Physics Department, St. Francis Xavier University, Antigonish, Nova Scotia B2G 2W5 (Canada)

    2013-12-21

    Ultra-small angle X-ray scattering has been used for the first time to elucidate, in situ, the aggregation structure of a model edible oil system. The three-dimensional nano- to micro-structure of tristearin solid particles in triolein solvent was investigated using 5, 10, 15, and 20% solids. Three different sample preparation procedures were investigated: two slow cooling rates of 0.5°/min, case 1 (22 days of storage at room temperature) and case 2 (no storage), and one fast cooling of 30°/min, case 3 (no storage). The length scale investigated, by using the Bonse-Hart camera at beamline ID-15D at the Advanced Photon Source, Argonne National Laboratory, covered the range from 300 Å to 10 μm. The unified fit and the Guinier-Porod models in the Irena software were used to fit the data. The former was used to fit 3 structural levels. Level 1 structures showed that the primary scatterers were essentially 2-dimensional objects for the three cases. The scatterers possessed lateral dimensions between 1000 and 4300 Å. This is consistent with the sizes of crystalline nanoplatelets present which were observed using cryo-TEM. Level 2 structures were aggregates possessing radii of gyration, R{sub g2} between 1800 Å and 12000 Å and fractal dimensions of either D{sub 2}=1 for case 3 or 1.8≤D{sub 2}≤2.1 for case 1 and case 2. D{sub 2} = 1 is consistent with unaggregated 1-dimensional objects. 1.8 ≤ D{sub 2} ≤ 2.1 is consistent with these 1-dimensional objects (below) forming structures characteristic of diffusion or reaction limited cluster-cluster aggregation. Level 3 structures showed that the spatial distribution of the level 2 structures was uniform, on the average, for case 1, with fractal dimension D{sub 3}≈3 while for case 2 and case 3 the fractal dimension was D{sub 3}≈2.2, which suggested that the large-scale distribution had not come to equilibrium. The Guinier-Porod model showed that the structures giving rise to the aggregates

  17. New insights into nucleation. Pressure trace measurements and the first small angle X-ray scattering experiments in a supersonic laval nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, D.

    2007-07-01

    Homogeneous nucleation rates of the n-alcohols and the n-alkanes have been determined by combining information from two sets of supersonic Laval nozzle expansion experiments under identical conditions. The nucleation rates J=N/{delta}t{sub Jmax} for the n-alcohols are in the range of 1.10{sup 17}Small Angle X-ray Scattering experiments are conducted to determine the particle number density for both substance classes. Particle number densities in the range of 1.10{sup 12}

  18. Count rates and structure factors in anomalous soft x-ray scattering from cuprate superconductors

    NARCIS (Netherlands)

    Abbamonte, P; Rusydi, A; Logvenov, G; Bozovic, [No Value; Sawatzky, GA; Venema, L.C.; Bozovic,; Pavuna, D

    2002-01-01

    It has recently been shown that x-ray diffraction from the doped holes in cuprates can be enhanced by 3-4 orders of magnitude by exploiting resonance effects in the oxygen K shell. This new type of anomalous scattering is direct way of probing ground state inhomogeneity in the mobile carrier liquid

  19. Soft Gamma Repeaters and Anomalous X-ray Pulsars: Magnetar Candidates

    Science.gov (United States)

    Woods, P. M.; Thompson, C.

    2005-01-01

    This article is a review of Soft Gamma Repeaters and Anomalous X-ray Pulsars. It contains a brief historical record of the emergence of these classes of neutron stars, a thorough overview of the observational data, a succinct summary of the magnetar model, and suggested directions for future research in this field.

  20. Structural and magnetic properties of inverse opal photonic crystals studied by x-ray diffraction, scanning electron microscopy, and small-angle neutron scattering

    NARCIS (Netherlands)

    Grigoriev, S.V.; Napolskii, K.S.; Grigoryeva, N.A.; Vasilieva, A.V.; Mistonov, A.A.; Chernyshov, D.Y.; Petukhov, A.V.; Belov, D.V.; Eliseev, A.A.; Lukashin, A.V.; Tretyakov, Y.D.; Sinitskii, A.S.; Eckerlebe, H.

    2009-01-01

    The structural and magnetic properties of nickel inverse opal photonic crystal have been studied by complementary experimental techniques, including scanning electron microscopy, wide-angle and small-angle diffraction of synchrotron radiation, and polarized neutrons. The sample was fabricated by ele

  1. Astrophysics of the Soft Gamma Repeaters and Anomalous X-Ray Pulsars

    OpenAIRE

    Thompson, Christopher

    2000-01-01

    I summarize the recent advances in our understanding of the Soft Gamma Repeaters: in particular their spin behavior, persistent emission and hyper-Eddington outbursts. The giant flares on 5 March 1979 and 27 August 1998 provide compelling physical evidence for magnetic fields stronger than 10 B_{QED} = 4.4 x 10^{14} G, consistent with the rapid spindown detected in two of these sources. The persistent X-ray emission and variable spindown of the 6-12 s Anomalous X-ray Pulsars are compared and ...

  2. Period Clustering of the Anomalous X-Ray Pulsars and Magnetic Field Decay in Magnetars.

    Science.gov (United States)

    Colpi; Geppert; Page

    2000-01-20

    We confront theoretical models for the rotational, magnetic, and thermal evolution of an ultramagnetized neutron star, or magnetar, with available data on the anomalous X-ray pulsars (AXPs). We argue that, if the AXPs are interpreted as magnetars, their clustering of spin periods between 6 and 12 s (observed at present in this class of objects), their period derivatives, their thermal X-ray luminosities, and the association of two of them with young supernova remnants can only be understood globally if the magnetic field in magnetars decays significantly on a timescale of the order of 104 yr.

  3. Dimyristoylphosphatidylcholine/C16 : 0-ceramide binary liposomes studied by differential scanning calorimetry and wide- and small-angle X-ray scattering

    DEFF Research Database (Denmark)

    Holopainen, J.M.; Lemmich, J.; Richter, F.;

    2000-01-01

    hydrated binary membranes composed of dimyristoylphosphatidylcholine (DMPC) and N-palmitoyl-ceramide (C16:0-ceramide, up to a mole fraction X-cer = 0.35) were resolved in further detail by high-sensitivity differential scanning calorimetry (DSC) and x-ray diffraction. Both methods reveal very strong...

  4. In Situ Lipolysis and Synchrotron Small-Angle X-ray Scattering for the Direct Determination of the Precipitation and Solid-State Form of a Poorly Water-Soluble Drug During Digestion of a Lipid-Based Formulation

    DEFF Research Database (Denmark)

    Khan, Jamal; Hawley, Adrian; Rades, Thomas;

    2016-01-01

    In situ lipolysis and synchrotron small-angle X-ray scattering (SAXS) were used to directly detect and elucidate the solid-state form of precipitated fenofibrate from the digestion of a model lipid-based formulation (LBF). This method was developed in light of recent findings that indicate...... variability in solid-state form upon the precipitation of some drugs during the digestion of LBFs, addressing the need to establish a real-time technique that enables solid-state analysis during in vitro digestion. In addition, an ex situ method was also used to analyse the pellet phase formed during...

  5. Advances in understanding the anomalous dispersion of plasmas in the X-ray regime

    Energy Technology Data Exchange (ETDEWEB)

    Nilsen, J; Cheng, K T; Johnson, W R

    2008-09-24

    Over the last several years we have predicted and observed plasmas with an index of refraction greater than one in the soft X-ray regime. These plasmas are usually a few times ionized and have ranged from low-Z carbon plasmas to mid-Z tin plasmas. Our main computational tool has been the average atom code AVATOMKG that enables us to calculate the index of refraction for any plasma at any wavelength. In the last year we have improved this code to take into account many-atomic collisions. This allows the code to converge better at low frequencies. In this paper we present our search for plasmas with strong anomalous dispersion that could be used in X-ray laser interferometer experiments to help understand this phenomena. We discuss the calculations of anomalous dispersion in Na vapor and Ne plasmas near 47 nm where we predict large effects. We also discuss higher Z plasmas such as Ce and Yb plasmas that look very interesting near 47 nm. With the advent of the FLASH X-ray free electron laser in Germany and the LCLS X-FEL coming online at Stanford in another year we use the average atom code to explore plasmas at higher X-ray energy to identify potential experiments for the future. In particular we look near the K shell lines of near solid carbon plasmas and predict strong effects. During the next decade X-ray free electron lasers and other X-ray sources will be available to probe a wider variety of plasmas at higher densities and shorter wavelengths so understanding the index of refraction in plasmas will be even more essential.

  6. Searching for plasmas with anomalous dispersion in the soft X-ray regime

    Energy Technology Data Exchange (ETDEWEB)

    Nilsen, J; Johnson, W R; Cheng, K T

    2007-08-24

    Over the last decade the electron density of plasmas has been measured using X-ray laser interferometers in the 14 to 47 nm wavelength regime. With the same formula used in decades of experiments with optical interferometers, the data analysis assumes the index of refraction is due only to the free electrons, which makes the index less than one. Over the last several years, interferometer experiments in C, Al, Ag, and Sn plasmas have observed plasmas with index of refraction greater than one at 14 or 47 nm and demonstrated unequivocally that the usual formula for calculating the index of refraction is not always valid as the contribution from bound electrons can dominate the free electrons in certain cases. In this paper we search for other materials with strong anomalous dispersion that could be used in X-ray laser interferometer experiments to help understand this phenomena. An average atom code is used to calculate the plasma properties. This paper discusses the calculations of anomalous dispersion in Ne and Na plasmas near 47 nm and Xe plasmas near 14 nm. With the advent of the FLASH X-ray free electron laser in Germany and the LCLS X-FEL coming online at Stanford in 2 years the average atom code will be an invaluable tool to explore plasmas at higher X-ray energy to identify potential experiments for the future. During the next decade X-ray free electron lasers and other X-ray sources will be used to probe a wider variety of plasmas at higher densities and shorter wavelengths so understanding the index of refraction in plasmas will be even more essential.

  7. An optical counterpart to the anomalous X-ray pulsar 4U0142+61.

    Science.gov (United States)

    Hulleman, F; van Kerkwijk, M H; Kulkarni, S R

    2000-12-01

    The energy source of the anomalous X-ray pulsars (AXPs) is not understood, hence their designation as anomalous. Unlike binary X-ray pulsars, no companions are seen, so the energy cannot be supplied by accretion of matter from a companion star. The loss of rotational energy, which powers radio pulsars, is insufficient to power AXPs. Two models are generally considered: accretion from a large disk left over from the birth process, or decay of a very strong magnetic field (10(15) G) associated with a 'magnetar'. The lack of counterparts at other wavelengths has hampered progress in our understanding of these objects. Here we report deep optical observations of the field around 4U0142+61, which is the brightest AXP in X-rays. The source has no associated supernova remnant, which, together with its spin-down timescale of approximately 10(5) yr (ref. 5), suggests that it may be relatively old. We find an object with peculiar optical colours at the position of the X-ray source, and argue that it is the optical counterpart. The optical emission is too faint to admit the presence of a large accretion disk, but may be consistent with magnetospheric emission from a magnetar.

  8. Small angle X-ray scattering-based elucidation of the self-association mechanism of human insulin analogue lys(B29)(N(e)¿-carboxyheptadecanoyl) des(B30)

    DEFF Research Database (Denmark)

    Jensen, Malene Hillerup; Wahlund, Per-Olof; Toft, Katrine Nørgaard;

    2013-01-01

    Lys(B29)(N(e)¿-carboxyheptadecanoyl) des(B30) human insulin is an insulin analogue belonging to a class of analogues designed to form soluble depots in subcutis by self-association, aiming at a protracted action. On the basis of small angle X-ray scattering (SAXS) supplemented by a range of bioph......Lys(B29)(N(e)¿-carboxyheptadecanoyl) des(B30) human insulin is an insulin analogue belonging to a class of analogues designed to form soluble depots in subcutis by self-association, aiming at a protracted action. On the basis of small angle X-ray scattering (SAXS) supplemented by a range...... provide evidence of the in solution structure of the self-associated oligomer, which is a long straight rod composed of "tense" state insulin hexamers (T(6)-hexamers) as the smallest repeating unit. The smallest oligomer building block in the process is a T(6)T(6)-dihexamer. This tense dihexamer is formed...... by the allosteric change of the initial equilibrium between a proposed "relaxed" state R(6)-hexamer and an R(3)T(3)T(3)R(3)-dihexamer. The allosteric change from relaxed to tense is triggered by removal of phenol, mimicking subcutaneous injection. The data hence provide the first unequivocal evidence...

  9. The Fading of Transient Anomalous X-Ray Pulsar XTE J1810-197

    Science.gov (United States)

    Halpern, J. P.; Gotthelf, E. V.

    2005-01-01

    Three observations of the 5.54 s transient anomalous X-ray pulsar XTE J1810-197 obtained over 6 months with the Newton X-ray Multi-Mirror (XMM-Newton) mission are used to study its spectrum and pulsed light curve as the source fades from outburst. The decay is consistent with an exponential of time constant ~300 days but not a power law as predicted in some models of sudden deep crustal heating events. All spectra are well fitted by a blackbody plus a steep power law, a problematic model that is commonly fitted to anomalous X-ray pulsars (AXPs). A two-temperature blackbody fit is also acceptable and better motivated physically in view of the faint optical/IR fluxes, the X-ray pulse shapes that weakly depend on energy in XTE J1810-197, and the inferred emitting areas that are less than or equal to the surface area of a neutron star. The fitted temperatures remained the same while the flux declined by 46%, which can be interpreted as a decrease in area of the emitting regions. The pulsar continues to spin down, albeit at a reduced rate of (5.1+/-1.6)×10-12 s s-1. The inferred characteristic age τc≡P/2P~17,000 yr, magnetic field strength Bs~1.7×1014 G, and outburst properties are consistent with both the outburst and quiescent X-ray luminosities being powered by magnetic field decay, i.e., XTE J1810-197 is a magnetar.

  10. Relation between the structure and catalytic activity for automotive emissions. Use of x-ray anomalous dispersion effect

    CERN Document Server

    Mizuki, J; Tanaka, H

    2003-01-01

    The employment of the X-ray anomalous dispersion effect allows us to detect the change in structure of catalytic converters with the environment exposed. Here we show that palladium atoms in a perovskite crystal move into and out of the crystal by anomalous X-ray diffraction and absorption techniques. This movement of the precious metal plays an important role to keep the catalytic activity long-lived. (author)

  11. Low-resolution structure of the full-length barley (Hordeum vulgare SGT1 protein in solution, obtained using small-angle X-ray scattering.

    Directory of Open Access Journals (Sweden)

    Michał Taube

    Full Text Available SGT1 is an evolutionarily conserved eukaryotic protein involved in many important cellular processes. In plants, SGT1 is involved in resistance to disease. In a low ionic strength environment, the SGT1 protein tends to form dimers. The protein consists of three structurally independent domains (the tetratricopeptide repeats domain (TPR, the CHORD- and SGT1-containing domain (CS, and the SGT1-specific domain (SGS, and two less conserved variable regions (VR1 and VR2. In the present study, we provide the low-resolution structure of the barley (Hordeum vulgare SGT1 protein in solution and its dimer/monomer equilibrium using small-angle scattering of synchrotron radiation, ab-initio modeling and circular dichroism spectroscopy. The multivariate curve resolution least-square method (MCR-ALS was applied to separate the scattering data of the monomeric and dimeric species from a complex mixture. The models of the barley SGT1 dimer and monomer were formulated using rigid body modeling with ab-initio structure prediction. Both oligomeric forms of barley SGT1 have elongated shapes with unfolded inter-domain regions. Circular dichroism spectroscopy confirmed that the barley SGT1 protein had a modular architecture, with an α-helical TPR domain, a β-sheet sandwich CS domain, and a disordered SGS domain separated by VR1 and VR2 regions. Using molecular docking and ab-initio protein structure prediction, a model of dimerization of the TPR domains was proposed.

  12. Structure determination of thin CoFe films by anomalous x-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Gloskovskii, Andrei; Stryganyuk, Gregory; Ouardi, Siham [Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany); Fecher, Gerhard H.; Felser, Claudia [Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany); Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden (Germany); Hamrle, Jaroslav; Pistora, Jaromir [Department of Physics and Nanotechnology Centre, VSB-Technical University of Ostrava, 70833 Ostrava (Czech Republic); Bosu, Subrojati; Saito, Kesami; Sakuraba, Yuya; Takanashi, Koki [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan)

    2012-10-01

    This work reports on the investigation of structure-property relationships in thin CoFe films grown on MgO. Because of the very similar scattering factors of Fe and Co, it is not possible to distinguish the random A2 (W-type) structure from the ordered B2 (CsCl-type) structure with commonly used x-ray sources. Synchrotron radiation based anomalous x-ray diffraction overcomes this problem. It is shown that as grown thin films and 300 K post annealed films exhibit the A2 structure with a random distribution of Co and Fe. In contrast, films annealed at 400 K adopt the ordered B2 structure.

  13. SARS E protein in phospholipid bilayers: an anomalous X-ray reflectivity study

    Energy Technology Data Exchange (ETDEWEB)

    Khattari, Z. [Institut fuer Roentgenphysik, Universitaet Goettingen, Geiststrasse 11, 37073 Goettingen (Germany); Brotons, G. [Institut fuer Roentgenphysik, Universitaet Goettingen, Geiststrasse 11, 37073 Goettingen (Germany); Arbely, E. [Alexander Silberman Institute of Life Sciences, Department of Biological Chemistry, Hebrew University of Jerusalem, Givat-Ram, Jerusalem, 91904 (Israel); Arkin, I.T. [Alexander Silberman Institute of Life Sciences, Department of Biological Chemistry, Hebrew University of Jerusalem, Givat-Ram, Jerusalem, 91904 (Israel); Metzger, T.H. [European Synchrotron Radiation Facility, Boite Postale 220, 38043 Grenoble (France); Salditt, T. [Institut fuer Roentgenphysik, Universitaet Goettingen, Geiststrasse 11, 37073 Goettingen (Germany)]. E-mail: tsaldit@gwdg.de

    2005-02-28

    We report on an anomalous X-ray reflectivity study to locate a labelled residue of a membrane protein with respect to the lipid bilayer. From such experiments, important constraints on the protein or peptide conformation can be derived. Specifically, our aim is to localize an iodine-labelled phenylalanine in the SARS E protein, incorporated in DMPC phospholipid bilayers, which are deposited in the form of thick multilamellar stacks on silicon surfaces. Here, we discuss the experimental aspects and the difficulties associated with the Fourier synthesis analysis that gives the electron density profile of the membranes.

  14. Soft gamma-ray repeaters and anomalous X-ray pulsars as highly magnetized white dwarfs

    CERN Document Server

    Mukhopadhyay, Banibrata

    2016-01-01

    We show that the soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) can be explained as recently proposed highly magnetized white dwarfs (B-WDs). The radius and magnetic field of B-WDs are perfectly adequate to explain energies in SGRs/AXPs as the rotationally powered energy. While the highly magnetized neutron stars require an extra, observationally not well established yet, source of energy, the magnetized white dwarfs, yet following Chandrasekhar's theory (C-WDs), exhibit large ultra-violet luminosity which is observationally constrained from a strict upper limit.

  15. Synchrotron Small Angle X-Ray Scattering Quantitatively Detects Angstrom Level Changes in the Average Radius of Taxol-Stabilized Microtubules Decorated with the Microtubule-Associated-Protein Tau

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Myung Chul; Raviv, Uri; Needleman, Daniel J; Safinya, Cyrus R [Materials Department, University of California Santa Barbara, CA 93106 (United States); Li, Youli [Materials Research Laboratory, University of California Santa Barbara, CA 93106 (United States); Miller, Herbert P; Wilson, Leslie; Feinstein, Stuart C [Molecular, Cellular, and Developmental Biology Departments, University of California Santa Barbara, CA 93106 (United States); Kim, Mahn Won, E-mail: myungchul.choi@gmail.com, E-mail: safinya@mrl.ucsb.edu [Department of Physics, KAIST, Daejeon 305-701, S. Korea (Korea, Republic of)

    2011-01-01

    With the emerging proteomics era the scientific community is beginning the daunting task of understanding the structures and functions of a large number of self-assembling proteins. Here, our study was concerned with the effect of the microtubule-associated-protein (MAP) tau on the assembled structure of taxol-stabilized microtubules. Significantly, the synchrotron small angle x-ray scattering (SAXS) technique is able to quantitatively detect angstrom level changes in the average diameter of the microtubules modeled as a simple hollow nanotube with a fixed wall thickness. We show that the electrostatic binding of MAP tau isoforms to taxol-stabilized MTs leads to a controlled increase in the average radius of microtubules with increasing coverage of tau on the MT surface. The increase in the average diameter results from an increase in the distribution of protofilament numbers in MTs upon binding of MAP tau.

  16. Determination of the size and phase composition of silver nanoparticles in a gel film of bacterial cellulose by small-angle X-ray scattering, electron diffraction, and electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, V. V.; Klechkovskaya, V. V., E-mail: klechvv@ns.crys.ras.ru; Shtykova, E. V.; Dembo, K. A.; Arkharova, N. A.; Ivakin, G. I. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Smyslov, R. Yu. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation)

    2009-03-15

    The nanoscale structural features in a composite (gel film of Acetobacter Xylinum cellulose with adsorbed silver nanoparticles, stabilized by N-polyvinylpyrrolidone) have been investigated by small-angle X-ray scattering. The size distributions of inhomogeneities in the porous structure of the cellulose matrix and the size distributions of silver nanoparticles in the composite have been determined. It is shown that the sizes of synthesized nanoparticles correlate with the sizes of inhomogeneities in the gel film. Particles of larger size (with radii up to 100 nm) have also been found. Electron microscopy of thin cross sections of a dried composite layer showed that large particles are located on the cellulose layer surface. Electron diffraction revealed a crystal structure of silver nanoparticles in the composite.

  17. The structural diversity of DNA-neutral phospholipids-divalent metal cations aggregates: a small-angle synchrotron X-ray diffraction study.

    Science.gov (United States)

    Uhríková, Daniela; Lengyel, Adrián; Hanulová, Mária; Funari, Sérgio S; Balgavý, Pavol

    2007-04-01

    We investigate the structure of aggregates formed due to DNA interaction with saturated neutral phosphatidylcholines [dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine] in presence of Ca(2+) and Mg(2+) cations using simultaneous synchrotron small- and wide-angle X-ray diffractions. For DPPC:DNA = 3:1 mol/base and in the range of 1-50 mM Ca(2+), the diffractograms show structural heterogeneity of aggregates. We observe the coexistence of two lamellar phases in aggregates prepared at 1 mM Ca(2+): L(x) phase with the DNA strands (of unknown organization) intercalated in water layers between adjacent lipid bilayers and L(DPPC) phase of DPPC bilayers without any divalent cations and DNA strands. Aggregates prepared in the range 2-50 mM Ca(2+) show a condensed gel lamellar phase L (g) (c) with the lipid bilayer periodicity d approximately 8.0 nm, and the DNA-DNA interhelical distance d (DNA) approximately 5.1 nm. The increase of temperature induces the decrease in the intensity and the increase in the width of the DNA related peak. In the fluid state, the condensed lamellar phase L (alpha) (c) gradually converts into L(x) phase. The aggregates do not exhibit rippled P(beta) phase. The thermal behaviour of aggregates was investigated in the range 20-80 degrees C. Applying heating-cooling cycles, the aggregates converted into energetically more favourable structure: a condensed lamellar phase L(c) (or L(x)) is preserved or we observe lateral segregation of the DNA strands and metal cations (L(x) phase) in coexistence with L(PC) phase of pure phospholipids. PMID:16865363

  18. Long-term evolution of anomalous X-ray pulsars and soft gamma repeaters

    CERN Document Server

    Benli, Onur

    2016-01-01

    We have investigated the long-term evolution of individual anomalous X-ray pulsars (AXPs) and soft gamma repeaters (SGRs) with relatively well constrained X-ray luminosity and rotational properties. In the frame of the fallback disc model, we have obtained the ranges of disc mass and dipole field strength that can produce the observed source properties. We have compared our results with those obtained earlier for dim isolated neutron stars (XDINs). Our results show that (1) the X-ray luminosity, period and period derivative of the individual AXP/SGR sources can be produced self-consistently in the fallback disc model with very similar basic disc parameters to those used earlier in the same model to explain the long-term evolution of XDINs, (2) except two sources, AXP/SGRs are evolving in the accretion phase; these two exceptional sources, like XDINs, completed their accretion phase in the past and are now evolving in the final propeller phase and still slowing down with the disc torques, (3) the dipole field ...

  19. Optical pulsations from the anomalous X-ray pulsar 4U0142+61.

    Science.gov (United States)

    Kern, B; Martin, C

    2002-05-30

    Anomalous X-ray pulsars (AXPs) differ from ordinary radio pulsars in that their X-ray luminosity is orders of magnitude greater than their rate of rotational energy loss, and so they require an additional energy source. One possibility is that AXPs are highly magnetized neuron stars or 'magnetars' having surface magnetic fields greater than 10(14) G. This would make them similar to the soft gamma-ray repeaters (SGRs), but alternative models that do not require extreme magnetic fields also exist. An optical counterpart to the AXP 4U0142+61 was recently discovered, consistent with emission from a magnetar, but also from a magnetized hot white dwarf, or an accreting isolated neutron star. Here we report the detection of optical pulsations from 4U0142+61. The pulsed fraction of optical light (27 per cent) is five to ten times greater than that of soft X-rays, from which we conclude that 4U0142+61 is a magnetar. Although this establishes a direct relationship between AXPs and the soft gamma-ray repeaters, the evolutionary connection between AXPs, SGRs and radio pulsars remains controversial.

  20. Probing the surface microstructure of layer-by-layer self-assembly chitosan/poly(l-glutamic acid) multilayers: A grazing-incidence small-angle X-ray scattering study.

    Science.gov (United States)

    Zhao, Nie; Yang, Chunming; Wang, Yuzhu; Zhao, Binyu; Bian, Fenggang; Li, Xiuhong; Wang, Jie

    2016-01-01

    This study characterized the surface structure of layer-by-layer self-assembly chitosan/poly(L-glutamic acid) multilayers through grazing-incidence small-angle X-ray scattering (GISAXS), X-ray reflectivity (XRR), and atomic force microscopy (AFM). A weakly long-period ordered structure along the in-plane direction was firstly observed in the polyelectrolyte multilayer by the GISAXS technique. This structure can be attributed to the specific domains on the film surface. In the domain, nanodroplets that were formed by polyelectrolyte molecules were orderly arranged along the free surface of the films. This ordered structure gradually disappeared with the increasing bilayer number because of the complex merging behavior of nanodroplets into large islands. Furthermore, resonant diffuse scattering became evident in the GISAXS patterns as the number of bilayers in the polyelectrolyte multilayer was increased. Notably, the lateral cutoff length of resonant diffuse scattering for these polyelectrolyte films was comparable with the long-period value of the ordered nanodroplets in the polyelectrolyte multilayer. Therefore, the nanodroplets could be considered as a basic transmission unit for structure propagation from the inner interface to the film surface. It suggests that the surface structure with length scale larger than the size of nanodroplets was partially complicated from the interface structure near the substrate, but surface structure smaller than the cutoff length was mainly depended on the conformation of nanodroplets. PMID:26478320

  1. X-ray and Near-IR Variability of the Anomalous X-ray Pulsar 1E 1048.1-5937: From Quiescence Back to Activity

    CERN Document Server

    Tam, Cindy R; Dib, Rim; Kaspi, Victoria M; Woods, Peter M; Bassa, Cees

    2007-01-01

    (Abridged) Monitoring of the anomalous X-ray pulsar 1E 1048.1-5937 in 2005-2006 with the RXTE, CXO, and HST has revealed that the source entered a phase of X-ray and near-IR radiative quiescence, simultaneous with timing stability. During its ~2001-2004 active period, the source exhibited two large, long-term X-ray pulsed-flux flares as well as short bursts, and large (>10x) torque changes. A series of four simultaneous observations with CXO and HST approximately equispaced in 2006 showed that its X-ray flux and spectrum and near-IR flux, both variable prior to 2005, stabilized. The near-IR flux (m_{F110W} > 24.8 mag, m_{F160W} ~ 22.70 mag) is considerably fainter in 2006 than previously measured. Recently, in 2007 March, this newfound quiescence was interrupted by a sudden flux enhancement, spectral changes and a pulse morphology change, simultaneous with a large spin-up glitch and near-IR enhancement. Specifically, our RXTE observations revealed a sudden pulsed flux increase by a factor of ~3 in the 2-10 ke...

  2. Anomalous elastic scattering of x-ray photon by an atom with an open shell

    International Nuclear Information System (INIS)

    In the non-relativistic approximation for the wavefunctions of the one-electron states and in the dipole approximation for the scattering amplitude the effect of relaxation of atomic shells in the field of core vacancies, multiplet splitting, Auger and radiative vacancy decays and virtual processes of one-photon double excitation/ionization from the atomic ground state on the differential cross section of anomalous elastic scattering of the linearly polarized x-ray photon by the copper atom near its 1s-shell ionization threshold are studied. The results of calculations are found to be in agreement with the high-precision synchrotron radiation experiment by Arp et al (1993 J. Phys. B: At. Mol. Opt. Phys. 26 4381)

  3. Anomalous elastic scattering of x-ray photon by an atom with an open shell

    Energy Technology Data Exchange (ETDEWEB)

    Hopersky, A N; Petrov, I D; Nadolinsky, A M; Yavna, V A; Koneev, R V [Rostov State University of Transport Communication, Chair of Mathematics, Rostov-on-Don, 344038 (Russian Federation)

    2004-08-28

    In the non-relativistic approximation for the wavefunctions of the one-electron states and in the dipole approximation for the scattering amplitude the effect of relaxation of atomic shells in the field of core vacancies, multiplet splitting, Auger and radiative vacancy decays and virtual processes of one-photon double excitation/ionization from the atomic ground state on the differential cross section of anomalous elastic scattering of the linearly polarized x-ray photon by the copper atom near its 1s-shell ionization threshold are studied. The results of calculations are found to be in agreement with the high-precision synchrotron radiation experiment by Arp et al (1993 J. Phys. B: At. Mol. Opt. Phys. 26 4381)

  4. Nano-structured titanium and aluminium nitride coatings: Study by grazing incidence X-ray diffraction and X-ray absorption and anomalous diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Tuilier, M.-H., E-mail: marie-helene.tuilier@uha.fr [Universite de Haute Alsace (UHA), Laboratoire Physique et Mecanique Textile (LPMT), EA 4365 -conventionnee au CNRS, Equipe PPMR, F-68093 Mulhouse (France); Pac, M.-J. [Universite de Haute Alsace (UHA), Laboratoire Physique et Mecanique Textile (LPMT), EA 4365 - conventionnee au CNRS, Equipe PPMR, F-68093 Mulhouse (France); Anokhin, D.V. [Universite de Haute Alsace (UHA), CNRS, Institut de Science des Materiaux de Mulhouse (IS2M), LRC 7228, F-68093 Mulhouse (France); Moscow State University, Faculty of Fundamental Physical and Chemical Engineering, 119991, Moscow, GSP-1, 1-51 Leninskie Gory (Russian Federation); Ivanov, D.A. [Universite de Haute Alsace (UHA), CNRS, Institut de Science des Materiaux de Mulhouse (IS2M), LRC 7228, F-68093 Mulhouse (France); Rousselot, C. [Universite de Franche-Comte, FEMTO-ST (UMR CNRS 6174), F-25211 Montbeliard (France); Thiaudiere, D. [Synchrotron Soleil, Saint Aubin, F-91192 Gif sur Yvette (France)

    2012-12-30

    Titanium and aluminium nitride thin films, Ti{sub 1-x}Al{sub x}N (x = 0, x = 0.5, x = 0.68), deposited by reactive magnetron sputtering on silicon substrates are investigated by combining two different X-ray diffraction experiments carried out using synchrotron radiation. Grazing-incidence X-ray diffraction and Ti K-edge diffraction anomalous near edge structure spectroscopy provide information on the micro- and nano-structure of the films respectively, which play a crucial role in the functionality of coatings. The spectroscopic data of Ti{sub 0.50}Al{sub 0.50}N film show that Ti atoms in crystallized domains and grain boundaries are all in octahedral cubic local order, but their growth mode is quite different. It is found that the crystallized part of the Ti{sub 0.50}Al{sub 0.50}N film has a single-crystalline nature, whereas the TiN one presents a fibrillar microstructure. For Ti{sub 0.32}Al{sub 0.68}N film, grazing-incidence X-ray diffraction provides information on the uniaxial texture along the [001] direction of the hexagonal lattice. A sharp Ti K pre-edge peak is observed in diffraction anomalous near edge spectrum that definitely shows that Ti atoms are incorporated in the hexagonal lattice of those fibrillar domains. Moreover, the difference observed between Ti K-edge diffraction anomalous and X-ray absorption pre-edge regions proves that a significant part of Ti atoms is located in nanocrystallites with cubic symmetry outside of the crystallized domains. - Highlights: Black-Right-Pointing-Pointer We study nano and micro-structures of TiN, Ti{sub 0.50}Al{sub 0.50}N and Ti{sub 0.32}Al{sub 0.68}N films. Black-Right-Pointing-Pointer Anomalous diffraction solves the crystallized part regardless of grain boundaries. Black-Right-Pointing-Pointer TiN microstructure is fibrillar, Ti{sub 0.5}Al{sub 0.5}N presents single crystalline domains. Black-Right-Pointing-Pointer For Ti{sub 0.32}Al{sub 0.68}N, Ti atoms are located in nanocrystallites with cubic symmetry

  5. Small-angle X-ray scattering analysis reveals the ATP-bound monomeric state of the ATPase domain from the homodimeric MutL endonuclease, a GHKL phosphotransferase superfamily protein.

    Science.gov (United States)

    Iino, Hitoshi; Hikima, Takaaki; Nishida, Yuya; Yamamoto, Masaki; Kuramitsu, Seiki; Fukui, Kenji

    2015-05-01

    DNA mismatch repair is an excision system that removes mismatched bases chiefly generated by replication errors. In this system, MutL endonucleases direct the excision reaction to the error-containing strand of the duplex by specifically incising the newly synthesized strand. Both bacterial homodimeric and eukaryotic heterodimeric MutL proteins belong to the GHKL ATPase/kinase superfamily that comprises the N-terminal ATPase and C-terminal dimerization regions. Generally, the GHKL proteins show large ATPase cycle-dependent conformational changes, including dimerization-coupled ATP binding of the N-terminal domain. Interestingly, the ATPase domain of human PMS2, a subunit of the MutL heterodimer, binds ATP without dimerization. The monomeric ATP-bound state of the domain has been thought to be characteristic of heterodimeric GHKL proteins. In this study, we characterized the ATP-bound state of the ATPase domain from the Aquifex aeolicus MutL endonuclease, which is a homodimeric GHKL protein unlike the eukaryotic MutL. Gel filtration, dynamic light scattering, and small-angle X-ray scattering analyses clearly showed that the domain binds ATP in a monomeric form despite its homodimeric nature. This indicates that the uncoupling of dimerization and ATP binding is a common feature among bacterial and eukaryotic MutL endonucleases, which we suggest is closely related to the molecular mechanisms underlying mismatch repair. PMID:25809295

  6. Structural dynamics and ssDNA binding activity of the three N-terminal domains of the large subunit of Replication Protein A from small angle X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Pretto, Dalyir I.; Tsutakawa, Susan; Brosey, Chris A.; Castillo, Amalchi; Chagot, Marie-Eve; Smith, Jarrod A.; Tainer, John A.; Chazin, Walter J.

    2010-03-11

    Replication Protein A (RPA) is the primary eukaryotic ssDNA binding protein utilized in diverse DNA transactions in the cell. RPA is a heterotrimeric protein with seven globular domains connected by flexible linkers, which enable substantial inter-domain motion that is essential to its function. Small angle X-ray scattering (SAXS) experiments on two multi-domain constructs from the N-terminus of the large subunit (RPA70) were used to examine the structural dynamics of these domains and their response to the binding of ssDNA. The SAXS data combined with molecular dynamics simulations reveal substantial interdomain flexibility for both RPA70AB (the tandem high affinity ssDNA binding domains A and B connected by a 10-residue linker) and RPA70NAB (RPA70AB extended by a 70-residue linker to the RPA70N protein interaction domain). Binding of ssDNA to RPA70NAB reduces the interdomain flexibility between the A and B domains, but has no effect on RPA70N. These studies provide the first direct measurements of changes in orientation of these three RPA domains upon binding ssDNA. The results support a model in which RPA70N remains structurally independent of RPA70AB in the DNA bound state and therefore freely available to serve as a protein recruitment module.

  7. Application of focused-beam flat-sample method to synchrotron powder X-ray diffraction with anomalous scattering effect

    Science.gov (United States)

    Tanaka, M.; Katsuya, Y.; Matsushita, Y.

    2013-03-01

    The focused-beam flat-sample method (FFM), which is a method for high-resolution and rapid synchrotron X-ray powder diffraction measurements by combination of beam focusing optics, a flat shape sample and an area detector, was applied for diffraction experiments with anomalous scattering effect. The advantages of FFM for anomalous diffraction were absorption correction without approximation, rapid data collection by an area detector and good signal-to-noise ratio data by focusing optics. In the X-ray diffraction experiments of CoFe2O4 and Fe3O4 (By FFM) using X-rays near the Fe K absorption edge, the anomalous scattering effect between Fe/Co or Fe2+/Fe3+ can be clearly detected, due to the change of diffraction intensity. The change of observed diffraction intensity as the incident X-ray energy was consistent with the calculation. The FFM is expected to be a method for anomalous powder diffraction.

  8. Small-angle x-ray scattering studies of calmodulin mutants with deletions in the linker region of the central helix indicate that the linker region retains a predominantly. alpha. -helical conformation

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, Mikio; Engelman, D.M. (Yale Univ., New Haven, CT (USA)); Head, J.F. (Boston Univ., MA (USA)); Persechini, A.; Kretsinger, R.H. (Univ. of Virginia, Charlottesville (USA))

    1991-02-05

    Two mutant forms of calmodulin were examined by small-angle X-ray scattering in solution and compared with the wild-type protein. Each mutant has deletions in the linker region of the central helix: one lacks residues Glu-83 and Glu-84 (Des2) and the other lacks residues Ser-81 through Glu-84 (Des4). The deletions change both the radii of gyration and the maximum dimensions of the molecules. In the presence of Ca{sup 2+}, the observed radii of gyration are 22.4 {angstrom} for wild-type bacterially expressed calmodulin, 19.5 {angstrom} for Des2 calmodulin, and 20.3 {angstrom} for Des4 calmodulin. A reduction in the radius of gyration by 1-2 {angstrom} on removal of calcium, previously observed in the native protein, was also found in the wild type and the Des4 mutant; however, no significant size change was observed in the Des2 mutant. The large calcium-dependent conformational change in calmodulin induced by the binding of melittin was observed in all the bacterially expressed proteins. Each protein appears to undergo a transition from a dumbbell shape to a more globular conformation on binding melittin in the presence of calcium, although quantitatively the changes in the wild-type and Des4 proteins greatly exceed those in Des2. Modeling shows that the structural properties of the deletion mutants are well described by modifications of an {alpha} helix in the central linker region of the molecule. Thus, the structure of the linker region is stable enough to maintain the average orientation and separation of the lobes yet flexible enough to permit the lobes to approach each other upon binding a peptide.

  9. Small-angle x-ray scattering studies of calmodulin mutants with deletions in the linker region of the central helix indicate that the linker region retains a predominantly α-helical conformation

    International Nuclear Information System (INIS)

    Two mutant forms of calmodulin were examined by small-angle X-ray scattering in solution and compared with the wild-type protein. Each mutant has deletions in the linker region of the central helix: one lacks residues Glu-83 and Glu-84 (Des2) and the other lacks residues Ser-81 through Glu-84 (Des4). The deletions change both the radii of gyration and the maximum dimensions of the molecules. In the presence of Ca2+, the observed radii of gyration are 22.4 angstrom for wild-type bacterially expressed calmodulin, 19.5 angstrom for Des2 calmodulin, and 20.3 angstrom for Des4 calmodulin. A reduction in the radius of gyration by 1-2 angstrom on removal of calcium, previously observed in the native protein, was also found in the wild type and the Des4 mutant; however, no significant size change was observed in the Des2 mutant. The large calcium-dependent conformational change in calmodulin induced by the binding of melittin was observed in all the bacterially expressed proteins. Each protein appears to undergo a transition from a dumbbell shape to a more globular conformation on binding melittin in the presence of calcium, although quantitatively the changes in the wild-type and Des4 proteins greatly exceed those in Des2. Modeling shows that the structural properties of the deletion mutants are well described by modifications of an α helix in the central linker region of the molecule. Thus, the structure of the linker region is stable enough to maintain the average orientation and separation of the lobes yet flexible enough to permit the lobes to approach each other upon binding a peptide

  10. Buffer-induced swelling and vesicle budding in binary lipid mixtures of dioleoylphosphatidylcholine:dioleoylphosphatidylethanolamine and dioleoylphosphatidylcholine:lysophosphatidylcholine using small-angle X-ray scattering and ³¹P static NMR.

    Science.gov (United States)

    Barriga, Hanna M G; Bazin, Richard; Templer, Richard H; Law, Robert V; Ces, Oscar

    2015-03-17

    A large variety of data exists on lipid phase behavior; however, it is mostly in nonbuffered systems over nonbiological temperature ranges. We present biophysical data on lipid mixtures of dioleoylphosphatidylcholine (DOPC), dioleoylphosphatidylethanolamine (DOPE), and lysophosphatidylcholine (LysoPC) examining their behaviors in excess water and buffer systems over the temperature range 4-34 °C. These mixtures are commonly used to investigate the effects of spontaneous curvature on integral membrane proteins. Using small-angle X-ray scattering (SAXS) and (31)P NMR, we observed lamellar and vesicle phases, with the buffer causing an increase in the layer spacing. Increasing amounts of DOPE in a DOPC bilayer decreased the layer spacing of the mesophase, while the opposite trend was observed for increasing amounts of LysoPC. (31)P static NMR was used to analyze the DOPC:LysoPC samples to investigate the vesicle sizes present, with evidence of vesicle budding observed at LysoPC concentrations above 30 mol %. NMR line shapes were fitted using an adapted program accounting for the distortion of the lipids within the magnetic field. The distortion of the vesicle, because of magnetic susceptibility, varied with LysoPC content, and a discontinuity was found in both the water and buffer samples. Generally, the distortion increased with LysoPC content; however, at a ratio of DOPC:LysoPC 60:40, the sample showed a level of distortion of the vesicle similar to that of pure DOPC. This implies an increased flexibility in the membrane at this point. Commonly, the assumption is that for increasing LysoPC concentration there is a reduction in membrane tension, implying that estimations of membrane tension based on spontaneous curvature assumptions may not be accurate.

  11. The crystal structure and small-angle X-ray analysis of CsdL/TcdA reveal a new tRNA binding motif in the MoeB/E1 superfamily.

    Directory of Open Access Journals (Sweden)

    Miguel López-Estepa

    Full Text Available Cyclic N6-threonylcarbamoyladenosine ('cyclic t6A', ct(6A is a non-thiolated hypermodification found in transfer RNAs (tRNAs in bacteria, protists, fungi and plants. In bacteria and yeast cells ct(6A has been shown to enhance translation fidelity and efficiency of ANN codons by improving the faithful discrimination of aminoacylated tRNAs by the ribosome. To further the understanding of ct(6A biology we have determined the high-resolution crystal structures of CsdL/TcdA in complex with AMP and ATP, an E1-like activating enzyme from Escherichia coli, which catalyzes the ATP-dependent dehydration of t6A to form ct(6A. CsdL/TcdA is a dimer whose structural integrity and dimer interface depend critically on strongly bound K+ and Na+ cations. By using biochemical assays and small-angle X-ray scattering we show that CsdL/TcdA can associate with tRNA with a 1:1 stoichiometry and with the proper position and orientation for the cyclization of t6A. Furthermore, we show by nuclear magnetic resonance that CsdL/TcdA engages in transient interactions with CsdA and CsdE, which, in the latter case, involve catalytically important residues. These short-lived interactions may underpin the precise channeling of sulfur atoms from cysteine to CsdL/TcdA as previously characterized. In summary, the combination of structural, biophysical and biochemical methods applied to CsdL/TcdA has afforded a more thorough understanding of how the structure of this E1-like enzyme has been fine tuned to accomplish ct(6A synthesis on tRNAs while providing support for the notion that CsdA and CsdE are able to functionally interact with CsdL/TcdA.

  12. Study of Ordering for AOT/Water Lamellar Lyotropic Liquid Crystal: Small-angle X-ray Scattering Experiments%小角X射线散射表征AOT/水层状溶致液晶的有序性

    Institute of Scientific and Technical Information of China (English)

    庄文昌; 陈晓; 杨春杰; 王庐岩; 柴永存

    2005-01-01

    用小角X射线散射研究了AOT/水层状溶致液晶的有序性.通过对散射曲线的解析,讨论了表面活性剂浓度、温度和助表面活性剂等三个方面对溶致液晶层状相结构有序性的影响.在一定的范围内,提高温度,改变表面活性剂浓度和加入少量助表面活性剂可使碳氢链排列由稀疏转变为密实,层状相也相应地由"柔性双层"过渡到更加有序化的"平面双层".基于形状因子和体系内分子间作用力,提出了层状相形成与有序化的机理,同时采用分子模拟的方法展现了不同浓度下的液晶结构.%Small-angle X-ray scattering (SAXS) is utilized to study the ordering of AOT/water lamellar phase. As increasing surfactant concentration, temperature or adding cosurfactant in certain range, the arrangement of hydrocarbon chains will change from sparse to dense which results in the structural transformation of lamellar phase from "flexible"to "planar" bilayers. The possible mechanism is proposed based on shape factor and molecular interactions. Molecular simulations are also carried out to testify the obtained results.

  13. Bumpy Spin-Down of Anomalous X-Ray Pulsars The Link with Magnetars

    CERN Document Server

    Melatos, A

    1999-01-01

    The two anomalous X-ray pulsars (AXPs) with well-sampled timing histories, 1E 1048.1-5937 and 1E 2259+586, are known to spin down irregularly, with `bumps' superimposed on an overall linear trend. Here we show that if AXPs are non-accreting magnetars, i.e. isolated neutron stars with surface magnetic fields B_0 > 10^{10} T, then they spin down electromagnetically in exactly the manner observed, due to an effect called `radiative precession'. Internal hydromagnetic stresses deform the star, creating a fractional difference epsilon=(I_3-I_1)/I_1 ~ 10^{-8} between the principal moments of inertia I_1 and I_3; the resulting Eulerian precession couples to an oscillating component of the electromagnetic torque associated with the near-zone radiation fields, and the star executes an anharmonic wobble with period tau_pr ~ 2 pi / epsilon Omega(t) ~ 10 yr, where Omega(t) is the rotation frequency as a function of time t. We solve Euler's equations for a biaxial magnet rotating in vacuo; show that the computed Omega(t) ...

  14. Soft gamma-ray repeaters and anomalous X-ray pulsars as highly magnetized white dwarfs

    CERN Document Server

    Mukhopadhyay, Banibrata

    2016-01-01

    We explore the possibility that soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are powered by highly magnetized white dwarfs (B-WDs). We take a sample of SGRs and AXPs and provide the possible parameter space in mass, radius, and surface magnetic field based on their observed properties (period and its derivative) and the assumption that these sources obey the mass-radius relation derived for the B-WDs. The radius and magnetic field of B-WDs are adequate to explain energies in SGRs/AXPs as the rotationally powered energy. In addition, B-WDs also adequately explain the perplexing radio transient GCRT J1745-3009 as a white dwarf pulsar. Note that the radius and magnetic fields of B-WDs are neither extreme (unlike of highly magnetized neutron stars) nor ordinary (unlike of magnetized white dwarfs, yet following the Chandrasekhar's mass-radius relation (C-WDs)). In order to explain SGRs/AXPs, while the highly magnetized neutron stars require an extra, observationally not well established yet, ...

  15. Exceptional flaring activity of the anomalous X-ray pulsar 1E 1547.0-5408

    CERN Document Server

    Savchenko, V; Beckmann, V; Produit, N; Walter, R

    2009-01-01

    (Abridged) We studied an exceptional period of activity of the anomalous X-ray pulsar 1E 1547.0-5408 in January 2009, during which about 200 bursts were detected by INTEGRAL. The major activity episode happened when the source was outside the field of view of all the INTEGRAL instruments. But we were still able to study the properties of 84 bursts detected simultaneously by the anti-coincidence shield of the spectrometer SPI and by the detector of the imager ISGRI. We find that the luminosity of the 22 January 2009 bursts of 1E 1547.0-5408 was > 1e42 erg/s. This luminosity is comparable to that of the bursts of soft gamma repeaters (SGR) and is at least two orders of magnitude larger than the luminosity of the previously reported bursts from AXPs. Similarly to the SGR bursts, the brightest bursts of 1E 1547.0-5408 consist of a short spike of ~100 ms duration with a hard spectrum, followed by a softer extended tail of 1-10 s duration, which occasionally exhibits pulsations with the source spin period of ~2 s. ...

  16. Soft gamma-ray repeaters and anomalous X-ray pulsars as highly magnetized white dwarfs

    Science.gov (United States)

    Mukhopadhyay, Banibrata; Rao, A. R.

    2016-05-01

    We explore the possibility that soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are powered by highly magnetized white dwarfs (B-WDs). We take a sample of SGRs and AXPs and provide the possible parameter space in mass, radius, and surface magnetic field based on their observed properties (period and its derivative) and the assumption that these sources obey the mass-radius relation derived for the B-WDs. The radius and magnetic field of B-WDs are adequate to explain energies in SGRs/AXPs as the rotationally powered energy. In addition, B-WDs also adequately explain the perplexing radio transient GCRT J1745-3009 as a white dwarf pulsar. Note that the radius and magnetic fields of B-WDs are neither extreme (unlike of highly magnetized neutron stars) nor ordinary (unlike of magnetized white dwarfs, yet following the Chandrasekhar's mass-radius relation (C-WDs)). In order to explain SGRs/AXPs, while the highly magnetized neutron stars require an extra, observationally not well established yet, source of energy, the C-WDs predict large ultra-violet luminosity which is observationally constrained from a strict upper limit. Finally, we provide a set of basic differences between the magnetar and B-WD hypotheses for SGRs/AXPs.

  17. The Magnetar Nature and the Outburst Mechanism of a Transient Anomalous X-ray Pulsar

    Science.gov (United States)

    Guver, Tolga; Ozel, Feryal; Gogus, Ersin; Kouveliotou, Chryssa

    2007-01-01

    Anomalous X-ray Pulsars (AXPs) belong to a class of neutron stars believed to harbor the strongest magnetic fields in the universe, as indicated by their energetic bursts and their rapid spindowns. However, a direct measurement of their surface field strengths has not been made to date. It is also not known whether AXP outbursts result from changes in the neutron star magnetic field or crust properties. Here we report the first, spectroscopic measurement of the surface magnetic field strength of an AXP, XTE J1810-197, and solidify its magnetar nature. The field strength obtained from detailed spectral analysis and modeling is remarkably close to the value inferred from the rate of spindown of this source and remains nearly constant during numerous observations spanning over two orders of magnitude in source flux. The surface temperature, on the other hand, declines steadily and dramatically following the 2003 outburst of this source. Our findings demonstrate that heating occurs in the upper neutron star crust during an outburst and sheds light on the transient behaviour of AXPs.

  18. Detailed Physical Modeling Reveals the Magnetar Nature of a Transient Anomalous X-ray Pulsar

    Science.gov (United States)

    Guever, T.; Oezel, F.; Goegues, E.; Kouveliotou, C.

    2007-01-01

    Anomalous X-ray Pulsars (AXPs) belong to a class of neutron stars believed to harbor the strongest magnetic fields in the universe, as indicated by their energetic bursts and their rapid spindowns. However, a direct measurement of their surface field strengths has not been made to date. It is also not known whether AXP outbursts result from changes in the neutron star magnetic field or crust properties. Here we report the first, spectroscopic measurement of the surface magnetic field strength of an AXP, XTE J1810-197, and solidify its magnetar nature. The field strength obtained from detailed spectral analysis and modeling is remarkably close to the value inferred from the rate of spindown of this source and remains nearly constant during numerous observations spanning over two orders of magnitude in source flux. The surface temperature, on the other hand, declines steadily and dramatically following the 2003 outburst of this source. Our findings demonstrate that heating occurs in the upper neutron star crust during an outburst and sheds light on the transient behaviour of AXPs.

  19. Anomalous elastic scattering of x-ray photons by a neon-like ion

    Energy Technology Data Exchange (ETDEWEB)

    Hopersky, A N; Nadolinsky, A M; Dzuba, D V; Yavna, V A [Rostov State University of Transport Communication, Rostov-on-Don, 344038 (Russian Federation)

    2005-05-28

    In the non-relativistic approximation for the wavefunctions of the one-electron states and in the dipole approximation for the scattering amplitude, the effect of radial monopole rearrangement of electron shells within the field of a vacancy and of the processes of one-photon double excitation/ionization on the absolute values and the shapes of the differential cross sections of anomalous non-zero-angle elastic scattering of linearly polarized x-ray photons by the Ne atom and by the neon-like Si{sup 4+} and Ar{sup 8+} ions in the vicinity of K- and KL{sub 23}-ionization thresholds is studied. The results of calculations for the Ne atom were found to be in agreement with the high-precision synchrotron radiation experiments by Coreno et al (1999 Phys. Rev. A 59 2494; K-ionization threshold) and by Avaldi et al (1996 J. Phys. B: At. Mol. Opt. Phys. 29 L737; KL{sub 23}-ionization threshold). The results of calculations for the Si{sup 4+} and Ar{sup 8+} ions are predictions.

  20. Anomalous elastic scattering of x-ray photons by a neon-like ion

    International Nuclear Information System (INIS)

    In the non-relativistic approximation for the wavefunctions of the one-electron states and in the dipole approximation for the scattering amplitude, the effect of radial monopole rearrangement of electron shells within the field of a vacancy and of the processes of one-photon double excitation/ionization on the absolute values and the shapes of the differential cross sections of anomalous non-zero-angle elastic scattering of linearly polarized x-ray photons by the Ne atom and by the neon-like Si4+ and Ar8+ ions in the vicinity of K- and KL23-ionization thresholds is studied. The results of calculations for the Ne atom were found to be in agreement with the high-precision synchrotron radiation experiments by Coreno et al (1999 Phys. Rev. A 59 2494; K-ionization threshold) and by Avaldi et al (1996 J. Phys. B: At. Mol. Opt. Phys. 29 L737; KL23-ionization threshold). The results of calculations for the Si4+ and Ar8+ ions are predictions

  1. Atomic Rayleigh scattering cross-sections and the associated anomalous dispersion in the X-ray regions

    International Nuclear Information System (INIS)

    Elastic scattering cross-sections for Pd, Ag, Cd, In, Sn, Sb, Pt, Au and Pb are measured at an angle of 90 circle in the X-ray region 5.41≤E≤8.04 keV. These energies fall between the high-energy side of the L- and M-shell absorption edges of the atoms considered. The present atomic region is significant for solid X-rays to assess the contribution of resonance and solid-state environmental effects. Also it is the anomalous scattering region for many of the atoms of the periodic table. Experimental results are compared with theoretical calculations based on form factor formalisms including the anomalous corrections and available recent S-matrix values. Based on the experimental evidence, the present results indicate the influence of solid-state environmental effects, the importance of anomalous corrections nearer to absorption edges, the correctness of revised high-energy limit values, the superiority of S-matrix predictions over form factor values on measured elastic scattering cross-sections in the X-ray regime and also show the resonance behavior around K,L and M absorption edges. (orig.)

  2. 基于小角散射的柴油机排气颗粒的孔隙结构分析%Analysis of porosity structure of particles from diesel engine using small angle X-ray scattering

    Institute of Scientific and Technical Information of China (English)

    赵洋; 王忠; 李瑞那; 李铭迪; 王向丽

    2014-01-01

    Particles which contain soluble organic fraction (SOF), soot, and inorganic salt are mainly the result from an incomplete combustion or pyrolysis of fossil fuels and other organic materials. In a diesel engine, the poor mixing of fuel and air creates fuel-rich zones that support particle formation at high temperatures. Numerous studies show that they are harmful to human health when inhaled and may cause cancer. For that reason, it is important to reduce the formation or at least the emission of particles to the environment. Meanwhile, the strict regulations for particulate matter emission have been enforced in many developed countries. A diesel particulate filter (DPF) is currently the dominant diesel particulate emissions control technology to meet stringent air quality standards, however, the oxidation ability of particles is important to the regeneration of the filter bed in DPF. Temperature has a great influence on the oxidation process of particles. Many physical and chemical changes of particles happen at a high temperature, leading to porosity formation of particles during oxidation. The porosity structure of particles is important to the oxidation ability of particles. The micro-orifice uniform deposition impactor (MOUDI) is a favorable apparatus for obtaining the particle size distribution and collecting the particles in different size ranges after classification. Thermogravimetric analysis (TGA) has been widely used as an analytical method for investigating the relationship between the material weight and temperature under the condition of programming a temperature rise. The curve of the sample weight then can be obtained with the temperature. A derivative thermal gravimetry (DTG) curve, the first order differential to a TG curve, can reveal the features of mass variation with the temperature. Small-angle X-ray scattering (SAXS) is a widely used diffraction method for studying the structure of the sample. In this study, the micro-orifice uniform deposit

  3. Long-Term Spectral and Temporal Evolution of Anomalous X-Ray Pulsar XTE J1810-197

    Science.gov (United States)

    Vurgun, Eda; Gogus, Ersin; Chakraborty, Manoneeta; Guver, Tolga

    2016-07-01

    We present spectral and timing studies of the first transient Anomalous X-ray Pulsar XTE J1810-197, a 5.54 s pulsar discovered in 2003, when its X-ray luminosity increased ~100 fold. We investigate the long-term behaviour of the surface temperature,emitting area, and the pulsed fraction. X-ray spectra are well fitted by a two-component blackbody model in which the cool component is most likely arising from the whole surface of star and the hot component is arising from a relatively small hot spot on it. The spectral analysis has also shown evidence for the presence of an absorbtion line feature around 1.2 keV in almost all observations. We fit this absorption feature with an asymmetric gaussian component since it shows an asymmetric structure. The pulse fraction exhibits slightly different temporal evolution in higher and lower energy bands. We will discuss correlative behaviour between the spectral and timing parameters in order to constrain magnetar cooling models.

  4. Observation of parametric X-ray radiation in an anomalous diffraction region

    Science.gov (United States)

    Alexeyev, V. I.; Eliseyev, A. N.; Irribarra, E.; Kishin, I. A.; Kubankin, A. S.; Nazhmudinov, R. M.

    2016-08-01

    A new possibility to expand the energy region of diffraction processes based on the interaction of relativistic charged particles with crystalline structures is presented. Diffracted photons related to parametric X-ray radiation produced by relativistic electrons are detected below the low energy threshold for the X-ray diffraction mechanism in crystalline structures for the first time. The measurements were performed during the interaction of 7 MeV electrons with a textured polycrystalline tungsten foil and a highly oriented pyrolytic graphite crystal. The experiment results are in good agreement with a developed model based on the PXR kinematical theory. The developed experimental approach can be applied to separate the contributions of real and virtual photons to the total diffracted radiation generated during the interaction of relativistic charged particles with crystalline targets.

  5. A scenario of the formation of isolated X-ray pulsars with anomalously long period

    CERN Document Server

    Ikhsanov, N R; Beskrovnaya, N G

    2014-01-01

    A scenario of the formation of isolated X-ray pulsars is discussed with an application to one of the best studied objects of this class 1E 161348-5055. This moderately luminous, 10^33 - 10^35 erg/s, pulsar with a relatively soft spectrum, kT ~ 0.6-0.8 keV, is associated with an isolated neutron star, which is located near the center of the young (~2000 yr) compact supernova remnant RCW 103 and rotates steadily (|d\

  6. Long-Term RXTE Monitoring of the Anomalous X-ray Pulsar 1E 1048.1-5937

    CERN Document Server

    Kaspi, V M; Chakraborty, D; Lackey, J R; Muno, M P; Kaspi, Victoria M.; Gavriil, Fotis P.; Chakrabarty, Deepto; Lackey, Jessica R.; Muno, Michael P.

    2000-01-01

    We report on long-term monitoring of the anomalous X-ray pulsar (AXP) 1E 1048.1-5937 using the Rossi X-ray Timing Explorer (RXTE). The timing behavior of this pulsar is different from that of other AXPs being monitored with RXTE. In particular, we show that the pulsar shows significant deviations from simple spin-down such that phase-coherent timing has not been possible over time spans longer than a few months. We find that the deviations from simple spin down are not consistent with single "glitch" type events, nor are they consistent with radiative precession. We show that in spite of the rotational irregularities, the pulsar exhibits neither pulse profile changes nor large pulsed flux variations. We discuss the implications of our results for AXP models. In the context of the magnetar model, we suggest that 1E 1048.1-5937 may be a transition object between the soft gamma-ray repeater and AXP populations, and the AXP most likely to one day undergo an outburst.

  7. 10 Years of RXTE Monitoring of Anomalous X-ray Pulsar 4U 0142+61: Long-Term Variability

    CERN Document Server

    Dib, R; Gavriil, F P; Dib, Rim; Kaspi, Victoria M.; Gavriil, Fotis P.

    2006-01-01

    We report on 10 yr of monitoring of the 8.7-s Anomalous X-ray Pulsar 4U 0142+61 using the Rossi X-Ray Timing Explorer (RXTE). This pulsar exhibited stable rotation from 2000 until February 2006: the RMS phase residual for a spin-down model which includes nu, nudot, and nuddot is 2.3%. We report a possible phase-coherent timing solution valid over a 10-yr span extending back to March 1996. A glitch may have occured between 1998 and 2000, but it is not required by the existing data. We also report that the source's pulse profile has been evolving in the past 6 years, such that the dip of emission between its two peaks has been getting shallower since 2000, almost as if the profile is recovering to its pre-2000 morphology, in which there was no clear distinction between the peaks. These profile variations are seen in the 2-4 keV band but not in 6-8 keV. Finally, we present the pulsed flux time series of the source in 2-10 keV. There is evidence of a slow but steady increase in the source's pulsed flux since 2000...

  8. A glitch and an anti-glitch in the anomalous X-ray pulsar 1E 1841-045

    CERN Document Server

    Mus, Sinem Sasmaz; Gogus, Ersin

    2014-01-01

    We investigated the long-term spin properties of the anomalous X-ray pulsar (AXP) 1E 1841-045 by performing a temporal analysis of archival RXTE observations spanning about 5.2 yr from 2006 September to 2011 December. We identified two peculiar timing anomalies within ~1 yr of each other: a glitch with Delta(nu)/nu ~ 4.8 x 10^{-6} near MJD 54303; and an anti-glitch with Delta(nu)/nu ~ -5.8 x 10^{-7} near MJD 54656. The glitch that we identified, which is the fourth glitch seen in this source in the 13 yr of RXTE monitoring, is similar to the last two detected glitches. The anti-glitch from 1E 1841-045, however, is the first to be identified. The amplitude of the anti-glitch was comparable with that recently observed in AXP 1E 2259+586. We found no significant variations in the pulsed X-ray output of the source during either the glitch or the anti-glitch. We discuss our results in relation to the standard pulsar glitch mechanisms for the glitch, and to plausible magnetospheric scenarios for the anti-glitch.

  9. Characterising anomalous transport in accretion disks from X-ray observations

    CERN Document Server

    Greenhough, J; Chaty, S; Dendy, R O; Rowlands, G

    2002-01-01

    Whilst direct observations of internal transport in accretion disks are not yet possible, measurement of the energy emitted from accreting astrophysical systems can provide useful information on the physical mechanisms at work. Here we examine the unbroken multi-year time variation of the total X-ray flux from three sources: Cygnus X-1, the microquasar GRS1915+105, and for comparison the nonaccreting Crab nebula. To complement previous analyses, we demonstrate that the application of advanced statistical methods to these observational time-series reveals important contrasts in the nature and scaling properties of the transport processes operating within these sources. We find the Crab signal resembles Gaussian noise; the Cygnus X-1 signal is a leptokurtic random walk whose self-similar properties persist on timescales up to three years; and the GRS1915+105 signal is similar to that from Cygnus X-1, but with self-similarity extending possibly to only a few days. This evidence of self-similarity provides a robu...

  10. Study of quadrupolar transitions by 108.5 MeV 3He inelastic scattering at small angles. Anomalous behaviour of giant quadrupole resonance

    International Nuclear Information System (INIS)

    Giant resonances have been studied through the inelastic scattering of 108.5 MeV 3He on several nuclei. At the very small angles (theta 0), the quadrupole giant resonance experimental cross-section is about twice the value predicted by DWBA calculations based on a collective model. The comparison of the experimental data and the theoretical data calculations confirms the validity of DWBA for the first excited state of low energy and same multipolarity L = 2 at the very small angles. The angular distribution for L = 0 transition of energy close to that of the quadrupole giant resonance reaches its maximum at 00. The presence of an L = 0 component permits to describe the shape of the quadrupole giant resonance angular distribution, but difficulties are encountered when applying the sum rule for the heavy nuclei. Better agreement with the experimental angular distribution at small angles is obtained if a semimicroscopic convolution model of the quadrupole resonance is assumed. For excited states of low energy and multipolarity L not equal to 2, the results from the convolution model are as good as those from the standard collective model. The 2+ state in heavy nuclei is, however, much better described by the collective model

  11. A WHITE DWARF MERGER AS PROGENITOR OF THE ANOMALOUS X-RAY PULSAR 4U 0142+61?

    Energy Technology Data Exchange (ETDEWEB)

    Rueda, J. A.; Boshkayev, K.; Izzo, L.; Ruffini, R. [Dipartimento di Fisica and ICRA, Sapienza Universita di Roma, P.le Aldo Moro 5, I-00185 Rome (Italy); Loren-Aguilar, P. [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Kuelebi, B. [Institut de Ciencies de l' Espai (CSIC), Facultat de Ciencies, Campus UAB, Torre C5-parell, E-08193 Bellaterra (Spain); Aznar-Siguan, G.; Garcia-Berro, E., E-mail: jorge.rueda@icra.it, E-mail: enrique.garcia-berro@upc.edu [Institute for Space Studies of Catalonia, c/Gran Capita 2-4, Edif. Nexus 104, E-08034 Barcelona (Spain)

    2013-08-01

    It has been recently proposed that massive, fast-rotating, highly magnetized white dwarfs could describe the observational properties of some of soft gamma-ray repeaters and anomalous X-ray pulsars (AXPs). Moreover, it has also been shown that high-field magnetic white dwarfs can be the outcome of white dwarf binary mergers. The products of these mergers consist of a hot central white dwarf surrounded by a rapidly rotating disk. Here we show that the merger of a double degenerate system can explain the characteristics of the peculiar AXP 4U 0142+61. This scenario accounts for the observed infrared excess. We also show that the observed properties of 4U 0142+6 are consistent with an approximately 1.2 M{sub Sun} white dwarf, remnant of the coalescence of an original system made of two white dwarfs of masses 0.6 M{sub Sun} and 1.0 M{sub Sun }. Finally, we infer a post-merging age {tau}{sub WD} Almost-Equal-To 64 kyr and a magnetic field B Almost-Equal-To 2 Multiplication-Sign 10{sup 8} G. Evidence for such a magnetic field may come from the possible detection of the electron cyclotron absorption feature observed between the B and V bands at Almost-Equal-To 10{sup 15} Hz in the spectrum of 4U 0142+61.

  12. A white dwarf merger as progenitor of the anomalous X-ray pulsar 4U 0142+61?

    CERN Document Server

    Rueda, J A; Izzo, L; Ruffini, R; Aguilar, P Loren; Kulebi, B; Siguan, G Aznar; Berro, E Garcia

    2013-01-01

    It has been recently proposed that massive fast-rotating highly-magnetized white dwarfs could describe the observational properties of some of Soft Gamma-Ray Repeaters (SGRs) and Anomalous X-Ray Pulsars (AXPs). Moreover, it has also been shown that high-field magnetic (HFMWDs) can be the outcome of white dwarf binary mergers. The products of these mergers consist of a hot central white dwarf surrounded by a rapidly rotating disk. Here we show that the merger of a double degenerate system can explain the characteristics of the peculiar AXP 4U 0142+61. This scenario accounts for the observed infrared excess. We also show that the observed properties of 4U 0142+6 are consistent with an approximately $1.2 M_{\\sun}$ white dwarf, remnant of the coalescence of an original system made of two white dwarfs of masses $0.6\\, M_{\\sun}$ and $1.0\\, M_{\\sun}$. Finally, we infer a post-merging age $\\tau_{\\rm WD}\\approx 64$ kyr, and a magnetic field $B\\approx 2\\times 10^8$ G. Evidence for such a magnetic field may come from th...

  13. Determination of transition metal ion distribution in cubic spinel Co1.5Fe1.5O4 using anomalous x-ray diffraction

    Directory of Open Access Journals (Sweden)

    M. N. Singh

    2015-08-01

    Full Text Available We report anomalous x-ray diffraction studies on Co ferrite with composition Co1.5Fe1.5O4 to obtain the distribution of transition metal ions in tetrahedral and octahedral sites. We synthesize spinel oxide (Co1.5Fe1.5O4 through co-precipitation and subsequent annealing route. The imaginary part (absorption of the energy dependent anomalous form factor is measured and the real part is calculated theoretically through Kramers–Krönig transformation to analyze anomalous x-ray diffraction peak intensities. Fe and Co K-edge x-ray absorption near edge structure (XANES spectra are used to estimate charge states of transition metals. Our analysis, within experimental errors, suggests 44% of the tetrahedral sites contain Co in +2 oxidation state and the rest 56% sites contain Fe in +2 and +3 oxidation states. Similarly, 47% of the octahedral sites contain Fe in +3 oxidation states, whereas, the rest of the sites contain Co in +2 and +3 oxidation states. While a distinct pre-edge feature in the Fe K-edge XANES is observed, Co pre-edge remains featureless. Implications of these results to magnetism are briefly discussed.

  14. The 2006-2007 Active Phase of Anomalous X-ray Pulsar 4U 0142+61: Radiative and Timing Changes, Bursts, and Burst Spectral Features

    CERN Document Server

    Gavriil, Fotis P; Kaspi, Victoria M

    2009-01-01

    After at least 6 years of quiescence, Anomalous X-ray Pulsar (AXP) 4U 0142+61 entered an active phase in 2006 March that lasted several months and included six X-ray bursts as well as many changes in the persistent X-ray emission. The bursts, the first seen from this AXP in >11 years of Rossi X-ray Timing Explorer monitoring, all occurred in the interval between 2006 April 6 and 2007 February 7. The burst durations ranged from 8-3x10^3 s. The first five burst spectra are well modeled by blackbodies, with temperatures kT ~ 2-6 keV. However, the sixth burst had a complicated spectrum that is well characterized by a blackbody plus three emission features whose amplitude varied throughout the burst. The most prominent feature was at 14.0 keV. Upon entry into the active phase the pulsar showed a significant change in pulse morphology and a likely timing glitch. The glitch had a total frequency jump of 1.9+/-0.4 x 10^-7 Hz, which recovered with a decay time of 17+/-2 days by more than the initial jump, implying a n...

  15. The Long-term Radiative Evolution of Anomalous X-ray Pulsar 1E~2259+586 after its 2002 Outburst

    CERN Document Server

    Zhu, Weiwei; Woods, Peter M; Gavriil, Fotis P; Dib, Rim

    2007-01-01

    We present an analysis of five X-ray Multi-Mirror Mission (XMM) observations of the Anomalous X-ray Pulsar (AXP) 1E 2259+586 taken in 2004 and 2005 during its relaxation following its 2002 outburst. We compare these data with those of five previous XMM observations taken in 2002 and 2003, and find the observed flux decay is well described by a power-law of index -0.69+/-0.03. As of mid-2005, the source may still have been brighter than pre-outburst, and was certainly hotter. We find a strong correlation between hardness and flux, as seen in other AXP outbursts. We discuss the implications of these results for the magnetar model.

  16. Anomalous elastic scattering of linearly polarized X-ray radiation by multicharged atomic ions in the range of the ionization threshold of the 1s-shell

    Energy Technology Data Exchange (ETDEWEB)

    Hopersky, A.N. E-mail: phys@rgups.ru; Novikov, S.A.; Chuvenkov, V.V

    2002-04-01

    The absolute values and shape of differential cross-section of the process of the anomalous elastic scattering for non-zero angle are investigated within non-relativistic approximation for linearly polarized X-ray radiation scattered by multicharged atomic ions Ne{sup 6+} in the range of the ionization threshold of 1s-shell. The many-particle effects of radial rearrangement of electron shells in the field of an inner 1s-vacancy and the effect of vacancy stabilization are taken into account. The results of the work are predictions.

  17. Site-specific Incorporation of 3-Iodo-L-tyrosine into Proteins and Single-wavelength Anomalous Dispersion Phasing with Soft X-ray in Protein Crystallography

    Science.gov (United States)

    Murayama, Kazutaka; Sakamoto, Kensaku

    Iodine is a good anomalous scatter for radiations from in-house X-ray generators (Cu/CrKα). Non-natural amino acid, 3-iodo-L-tyrosine, is able to be site-specifically incorporated into proteins with amber suppresser tRNA and mutated TyrRS from M. jannaschii in the E. coli expression system. To determine the crystal structure of acetyl transferase from T. thermophilus, iodotyrosine-containing proteins were prepared and crystallized. Structure determination was successfully conducted with the protein variant with iodotyrosine at position 111. Anomalous signals from iodotyrosine with Cu/CrKα radiations were both sufficient to calculate clear electron density map. In the crystal structure, iodotyrosine did not significantly disturb the native structure.

  18. Determination of dopant site occupancies in Cu-substituted YBa2Cu3O7-δ by differential anomalous x-ray scattering

    Science.gov (United States)

    Howland, R. S.; Geballe, T. H.; Laderman, S. S.; Fischer-Colbrie, A.; Scott, M.; Tarascon, J. M.; Barboux, P.

    1989-05-01

    Dopant site occupancies in YBa2Cu3-xMxO7-δ, with M=Fe (x=0.3 and x=0.5), Co (x=0.2 and x=0.5), Ni (x=0.3), and Zn (x=0.3) have been found using differential anomalous x-ray scattering. The Ni and Zn atoms were found to occupy the Cu(1) (``chains'') site and the Cu(2) (``planes'') site in a nearly random distribution. The Fe and Co atoms were found to occupy the Cu(1) site predominantly at low x, with an increasing fraction on the Cu(2) sites as the total amount of dopant increases. In all cases, our results appear to have high statistical significance, with very little sensitivity to expected uncertainties in oxygen content, total dopant content, anomalous corrections to the atomic scattering factor of the dopant, and to relative atomic coordinates assumed in the modeling. We have also discussed the results in the context of existing extended x-ray-absorption fine-structure and neutron-diffraction results, thermogravimetric analysis, and Mössbauer spectra, and Tc and Hall-effect studies.

  19. Crowding and Anomalous Capacitance at an Electrode–Ionic Liquid Interface Observed Using Operando X-ray Scattering

    OpenAIRE

    Chu, Miaoqi; Miller, Mitchell; Dutta, Pulak

    2016-01-01

    Room temperature ionic liquids are widely recognized as novel electrolytes with properties very different from those of aqueous solutions, and thus with many potential applications, but observing how they actually behave at electrolytic interfaces has proved to be challenging. We have studied the voltage-dependent structure of [TDTHP]+[NTF2]− near its interface with an electrode, using in situ synchrotron X-ray reflectivity. An anion-rich layer develops at the interface above a threshold volt...

  20. Small angle neutron scattering

    Directory of Open Access Journals (Sweden)

    Cousin Fabrice

    2015-01-01

    Full Text Available Small Angle Neutron Scattering (SANS is a technique that enables to probe the 3-D structure of materials on a typical size range lying from ∼ 1 nm up to ∼ a few 100 nm, the obtained information being statistically averaged on a sample whose volume is ∼ 1 cm3. This very rich technique enables to make a full structural characterization of a given object of nanometric dimensions (radius of gyration, shape, volume or mass, fractal dimension, specific area… through the determination of the form factor as well as the determination of the way objects are organized within in a continuous media, and therefore to describe interactions between them, through the determination of the structure factor. The specific properties of neutrons (possibility of tuning the scattering intensity by using the isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons make it particularly interesting in the fields of soft matter, biophysics, magnetic materials and metallurgy. In particular, the contrast variation methods allow to extract some informations that cannot be obtained by any other experimental techniques. This course is divided in two parts. The first one is devoted to the description of the principle of SANS: basics (formalism, coherent scattering/incoherent scattering, notion of elementary scatterer, form factor analysis (I(q→0, Guinier regime, intermediate regime, Porod regime, polydisperse system, structure factor analysis (2nd Virial coefficient, integral equations, characterization of aggregates, and contrast variation methods (how to create contrast in an homogeneous system, matching in ternary systems, extrapolation to zero concentration, Zero Averaged Contrast. It is illustrated by some representative examples. The second one describes the experimental aspects of SANS to guide user in its future experiments: description of SANS spectrometer, resolution of the spectrometer, optimization of

  1. Crowding and Anomalous Capacitance at an Electrode-Ionic Liquid Interface Observed Using Operando X-ray Scattering.

    Science.gov (United States)

    Chu, Miaoqi; Miller, Mitchell; Dutta, Pulak

    2016-03-23

    Room temperature ionic liquids are widely recognized as novel electrolytes with properties very different from those of aqueous solutions, and thus with many potential applications, but observing how they actually behave at electrolytic interfaces has proved to be challenging. We have studied the voltage-dependent structure of [TDTHP](+)[NTF2](-) near its interface with an electrode, using in situ synchrotron X-ray reflectivity. An anion-rich layer develops at the interface above a threshold voltage of +1.75 V, and the layer thickness increases rapidly with voltage, reaching ∼6 nm (much larger that the anion dimensions) at +2.64 V. These results provide direct confirmation of the theoretical prediction of "crowding" of ions near the interface. The interfacial layer is not purely anionic but a mixture of up to ∼80% anions and the rest cations. The static differential capacitance calculated from X-ray measurements shows an increase at higher voltages, consistent with a recent zero-frequency capacitance measurement but inconsistent with ac capacitance measurements. PMID:27163044

  2. Crowding and Anomalous Capacitance at an Electrode–Ionic Liquid Interface Observed Using Operando X-ray Scattering

    Science.gov (United States)

    2016-01-01

    Room temperature ionic liquids are widely recognized as novel electrolytes with properties very different from those of aqueous solutions, and thus with many potential applications, but observing how they actually behave at electrolytic interfaces has proved to be challenging. We have studied the voltage-dependent structure of [TDTHP]+[NTF2]− near its interface with an electrode, using in situ synchrotron X-ray reflectivity. An anion-rich layer develops at the interface above a threshold voltage of +1.75 V, and the layer thickness increases rapidly with voltage, reaching ∼6 nm (much larger that the anion dimensions) at +2.64 V. These results provide direct confirmation of the theoretical prediction of “crowding” of ions near the interface. The interfacial layer is not purely anionic but a mixture of up to ∼80% anions and the rest cations. The static differential capacitance calculated from X-ray measurements shows an increase at higher voltages, consistent with a recent zero-frequency capacitance measurement but inconsistent with ac capacitance measurements. PMID:27163044

  3. Crowding and Anomalous Capacitance at an Electrode-Ionic Liquid Interface Observed Using Operando X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Miaoqi; Miller, Mitchell; Dutta, Pulak (NWU)

    2016-04-11

    Room temperature ionic liquids are widely recognized as novel electrolytes with properties very different from those of aqueous solutions, and thus with many potential applications, but observing how they actually behave at electrolytic interfaces has proved to be challenging. We have studied the voltage-dependent structure of [TDTHP]+[NTF2]- near its interface with an electrode, using in situ synchrotron X-ray reflectivity. An anion-rich layer develops at the interface above a threshold voltage of +1.75 V, and the layer thickness increases rapidly with voltage, reaching ~6 nm (much larger that the anion dimensions) at +2.64 V. Our results provide direct confirmation of the theoretical prediction of “crowding” of ions near the interface. The interfacial layer is not purely anionic but a mixture of up to ~80% anions and the rest cations. Moreover, the static differential capacitance calculated from X-ray measurements shows an increase at higher voltages, consistent with a recent zero-frequency capacitance measurement but inconsistent with ac capacitance measurements.

  4. Precise Localization of the Soft Gamma Repeater SGR 1627-41 with Chandra and the Anomalous X-Ray Pulsar AXP 1E1841-045 with Chandra

    Science.gov (United States)

    Wachter, Stefanie; Patel, Sandeep K.; Kouveliotou, Chryssa; Bouchet, Patrice; Ozel, Feryal; Tennant, Allyn F.; Woods, Peter M.; Hurley, Kevin; Becker, Werner; Slane, Patrick

    2004-01-01

    We present precise localizations of AXP 1E184-045 and SGR 1627-41 with Chandra. We obtained new infrared observations of SGR 1627-41 and reanalyzed archival observations of AXP 1E1841-045 in order to refine their positions and search for infrared counterparts. A faint source is detected inside the error circle of AXP 1E1841-045. In the case of SGR 1627-41, several sources are located within the error radius of the X-ray position, and we discuss the likelihood of one of them being the counterpart. We compare the properties of our candidates to those of other known anomalous X-ray pulsar (AXP) and soft gamma repeater (SGR) counterparts. We find that the counterpart candidates for SGR 1627-41 and SGR 1806-20 would have to be intrinsically much brighter than AXPs in order to have counterparts detectable with the observational limits currently available for these sources. To confirm the reported counterpart of SGR 1806-20, we obtained new infrared observations during the 2003 July burst activation of the source. No brightening of the suggested counterpart is detected, implying that the counterpart of SGR 1806-20 remains yet to be identified.

  5. RXTE Monitoring of the Anomalous X-ray Pulsar 1E 1048.1-5937: Long-Term Variability and the 2007 March Event

    CERN Document Server

    Dib, Rim; Gavriil, Fotis P

    2008-01-01

    After three years of no unusual activity, Anomalous X-ray Pulsar 1E 1048.1-5937 reactivated in 2007 March. We report on the detection of a large glitch (Delta(nu)/nu =1.63(2)X~10^{-5}) on 2007 March 26 (MJD 54185.9), contemporaneous with the onset of a pulsed-flux flare, the third flare observed from this source in 10 years of monitoring with the Rossi X-ray Timing Explorer. Additionally, we report on a detailed study of the evolution of the timing properties, the pulsed flux, and the pulse profile of this source as measured by RXTE from 1996 July to 2008 January. In our timing study, we attempted phase coherent timing of all available observations. We show that in 2001, a timing anomaly of uncertain nature occurred near the rise of the first pulsed flux flare; we show that a likely glitch (Delta(nu)/nu =2.91(9)X10^{-6}) occurred in 2002, near the rise of the second flare, and we present a detailed description of the variations in the spin-down. In our pulsed flux study, we compare the decays of the three fla...

  6. Anomalous lattice deformation in GaN/SiC(0001) measured by high-speed in situ synchrotron X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Takuo, E-mail: sasaki.takuo@jaea.go.jp; Takahasi, Masamitu [Quantum Beam Science Center, Japan Atomic Energy Agency, 1-1-1 Koto, Sayo, Hyogo 679-5148 (Japan); Ishikawa, Fumitaro [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan)

    2016-01-04

    We report an anomalous lattice deformation of GaN layers grown on SiC(0001) by molecular beam epitaxy. The evolution of the lattice parameters during the growth of the GaN layers was measured by in situ synchrotron X-ray diffraction. The lattice parameters in the directions parallel and normal to the surface showed significant deviation from the elastic strains expected for lattice-mismatched films on substrates up to a thickness of 10 nm. The observed lattice deformation was well explained by the incorporation of hydrostatic strains due to point defects. The results indicate that the control of point defects in the initial stage of growth is important for fabricating GaN-based optoelectronic devices.

  7. Anomalous decrease in X-ray diffraction intensities of Cu-Ni-Al-Co-Cr-Fe-Si alloy systems with multi-principal elements

    International Nuclear Information System (INIS)

    With an aim to understand the great reduction in the X-ray diffraction (XRD) intensities of high-entropy alloys, a series of Cu-Ni-Al-Co-Cr-Fe-Si alloys with systematic addition of principal elements from pure element to seven elements was investigated for quantitative analysis of XRD intensities. The variation of XRD peak intensities of the alloy system is similar to that caused by thermal effect, but the intensities further drop beyond the thermal effect with increasing number of incorporated principal elements. An intrinsic lattice distortion effect caused by the addition of multi-principal elements with different atomic sizes is expected for the anomalous decrease in XRD intensities. The mathematical factor of this distortion effect for the modification of XRD structure factor is formulated analogue to that of thermal effect

  8. 核磁共振、X射线小角散射以及计算机模拟相结合构建生物大分子复合物的结构模型%Determining Structural Models of Biomolecular Complexes Integrating Nuclear Magnetic Resonance, Small-Angle X-ray Scattering and Computational Simulations

    Institute of Scientific and Technical Information of China (English)

    彭俊辉; 赵德彪; 文彬; 张志勇

    2015-01-01

    Structural biology has been paying more attention on biomolecular complexes over the past decades, since they are crucial for many biological processes. Among these techniques for structural determination, nuclear magnetic resonance (NMR) has its advantage when dealing with biomolecules with high flexibility in solution. Small-angle X-ray scattering (SAXS) is a very important complementary technique that provides information on global shape of biomolecules. For biomolecular complexes, it can be much easier to determine atomic structures of individual subunits through NMR. In addition, NMR can also provide other structural information, such as the interface and orientations between subunits, and long range distance and angular restraints. Therefore, to construct structural models of biomolecular complexes, it would be very appropriate to combine experimental restraints obtained through NMR and low-resolution shape information from SAXS by utilizing computational tools, which is the main topic of this review.%近年来,结构生物学研究越来越注重生物大分子复合物的解析,因为许多重要生物学过程都离不开复合物的参与.溶液核磁共振是目前重要的结构解析方法之一.X射线小角散射(SAXS)作为一种新的结构生物学实验手段,近年来发展迅速.SAXS 能提供生物大分子复合物的较低分辨率结构信息,而核磁共振能解析复合物中各个亚基的原子分辨率结构.此外,通过核磁共振还能得到亚基之间的界面、取向以及距离信息.因此近年来通过计算机模拟,整合核磁共振和 SAXS 不同分辨率的结构信息,可以用来搭建生物大分子复合物的结构模型.该综述重点介绍这方面的研究进展.

  9. Determination of Dopant Site Occupancies in Copper - Yttrium-Barium by a New Application of Differential Anomalous X-Ray Scattering.

    Science.gov (United States)

    Gustafson, Rebecca Howland

    Dopant site occupancies in YBa_2 Cu_{rm 3-x}M _{rm x}O _{7-delta}, with M representing Fe (x = 0.3 and x = 0.5), Co (x = 0.2 and x = 0.5), Ni (x = 0.3) and Zn (x = 0.3) have been determined using an new application of differential anomalous x-ray scattering. The Ni and Zn atoms were found to occupy the Cu(1) ("chains") site and the Cu(2) ("planes") site in a nearly random distribution. The Fe and Co atoms were found to occupy the Cu(1) site predominantly at low x, with an increasing fraction on the Cu(2) sites as the total amount of dopant increases. In all cases, the results appear to have high statistical significance, with very little sensitivity to expected uncertainties in oxygen content, total dopant content, anomalous corrections to the atomic scattering factor of the dopant, and to relative atomic coordinates assumed in the modeling. The results are also discussed in the context of existing EXAFS and neutron diffraction results, thermogravimetric analysis and Mossbauer spectra, and T_{rm c} and Hall-effect studies.

  10. An Alternative Formation Theory of Beat. (II) Revelations of Recursion Formulas of the Reflected X-rays and the Anomalous Transmission and Absorption by the Binomial Theorem

    Science.gov (United States)

    Nakajima, Tetsuo

    2008-11-01

    The recursion formulas for the photon paths in the Borrmann triangle, which satisfy a new modified Pascal triangle can be derived from the binomial theorem by regarding the permutation of the stochastic variables of the diffracted and transmitted X-ray photons. The Borrmann triangle for the n-multiple X-ray reflections expanded by the n-degree binomial distribution consists of the two sub-triangles given by the ( n-1)-degree binomial distribution of the diffracted and transmitted photons. The former sub-triangle shows perfectly flawless symmetry but the latter one shows inevitable asymmetry. A reasonable understanding of both the high intense and very weak photon flows in the Borrmann triangle, which are popularly known as the anomalous transmission and absorption, respectively, are derived from the binomial theorem. Incident photons irradiated at a point O that forms the vertex of the Borrmann triangle propagate through the bypasses parallel to only the complementary half of the integral whole median with the high probabilities from the binomial theorem and emanate them from a short width slit of overline{O'O''} on the base of the high intense photon flow Borrmann triangle ▵ OO' O″, which can be defined by the standard deviation of the normal distribution. The parallel paths to the whole median also pass the very weak photon flows from the high power exponent of d multinomials through the triangle ▵ OO' O″. Both the above contrastive photon flows could coexist in ▵ OO' O″ based upon the complementary rivalry duality from the binomial theorem of ( d+ t) n =1, including the very weak photon flows from the high power exponent of t multinomials near both sides of the Borrmann triangle.

  11. Anomalous chemical shifts in X-ray photoelectron spectra of sulfur-containing compounds of silver (I) and (II)

    International Nuclear Information System (INIS)

    Highlights: • Ag 3d5/2 binding energy for Ag(II)SO4 is as large as 370.1 eV. • This is the largest value ever measured for a silver (II) compound. • Large shift is connected with the extreme oxidizing nature of Ag(II) species. • Ag(I)2S2O7 exhibits both positive and negative shifts with respect to metallic Ag. • Two distinct Ag(I) sites are responsible for large BE difference of 3.6 eV. - Abstract: Anomalous chemical shifts, i.e. cases when binding energy decreases with the increase of the oxidation state, have been well-documented for selected compounds of silver, and well understood based on analysis of initial- and final-state effects in the XPS spectra. Here we report two examples of even more exotic behaviour of chemical shifts for two silver compounds. The first one is Ag2S2O7 which exhibits both positive and negative substantial shifts with respect to metallic Ag for two distinct Ag(I) sites in its crystal structure, which differ by as much as 3.6 eV. Another is AgSO4, a rare example of oxo silver (II) salt, which exhibits “normal” chemical shift but the Ag 3d5/2 binding energy takes the largest value measured for a silver (II) compound (370.1 eV). This property is connected predominantly with the extremely strongly oxidizing nature of Ag(II) species

  12. A partial structure factor investigation of the bulk metallic glass Zr63Ni25Al12 as studied by using a combination of anomalous X-ray scattering and reverse Monte Carlo modeling

    International Nuclear Information System (INIS)

    Anomalous X-ray scattering experiments were performed on Zr63Ni25Al12 bulk metallic glass. The results were analyzed using reverse Monte Carlo modeling to obtain local- and intermediate-range atomic configurations of this good metallic glass former. Although the Al-related partial information is not reliable due to the small values of their weighting factors in X-ray scattering, good partial information could be obtained from a reverse Monte Carlo analysis. The obtained structural information is given by parameters such as bond angle distributions, bond orientation order parameters, the Warren-Cowley order parameters, and Voronoi polyhedra. Results are compared to the previous results from Fukunaga et al. using X-ray and neutron total scattering. (orig.)

  13. Structural analysis of Fe–Mn–O nanoparticles in glass ceramics by small angle scattering

    Energy Technology Data Exchange (ETDEWEB)

    Raghuwanshi, Vikram Singh, E-mail: vikram.raghuwanshi@helmholtz-berlin.de [Helmholtz Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, D-14109 Berlin (Germany); Harizanova, Ruzha [University of Chemical Technology and Metallurgy, 8 Kl. Ohridski Blvd, 1756 Sofia (Bulgaria); Tatchev, Dragomir [Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl. 11, 1113 Sofia (Bulgaria); Hoell, Armin [Helmholtz Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, D-14109 Berlin (Germany); Rüssel, Christian [Friedrich Schiller University, Fraunhoferstr. 6, 07743 Jena (Germany)

    2015-02-15

    Magnetic nanocrystals containing Fe and Mn were obtained by annealing of silicate glasses with the composition 13.6Na{sub 2}O–62.9SiO{sub 2}–8.5MnO–15.0Fe{sub 2}O{sub 3−x} (mol%) at 580 °C for different periods of time. Here, we present Small Angle Neutron Scattering using Polarized neutrons (SANSPOL) and Anomalous Small Angle X-ray Scattering (ASAXS) investigation on these glass ceramic samples. Analysis of scattering data from both methods reveals the formation of spherical core–shell type of nanoparticles with mean sizes between 10 nm and 100 nm. ASAXS investigation shows the particles have higher concentration of iron atoms and the shell like region surrounding the particles is enriched in SiO{sub 2}. SANSPOL investigation shows the particles are found to be magnetic and are surrounded by a non-magnetic shell-like region. - Graphical abstract: Magnetic spherical core–shell nanoparticles in glass ceramics: SANSPOL and ASAXS investigations. - Highlights: • Formation and growth mechanisms of magnetic nanoparticles in silicate glass. • SANSPOL and ASAXS methods employed to evaluate quantitative information. • Analyses showed formation of nanoparticles with spherical core–shell structures. • Core of the particle is magnetic and surrounded by weak magnetic shell like region.

  14. Theoretical concepts of X-ray nanoscale analysis theory and applications

    CERN Document Server

    Benediktovitch, Andrei; Ulyanenkov, Alexander

    2013-01-01

    This book provides a concise survey of modern theoretical concepts of X-ray materials analysis. The principle features of the book are: basics of X-ray scattering, interaction between X-rays and matter and new theoretical concepts of X-ray scattering. The various X-ray techniques are considered in detail: high-resolution X-ray diffraction, X-ray reflectivity, grazing-incidence small-angle X-ray scattering and X-ray residual stress analysis. All the theoretical methods presented use the unified physical approach. This makes the book especially useful for readers learning and performing data ana

  15. Determination of transition metal ion distribution in cubic spinel Co{sub 1.5}Fe{sub 1.5}O{sub 4} using anomalous x-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Singh, M. N. [Indus Synchrotrons Utilization Division, Raja Ramanna Center for Advanced Technology, Indore – 452013 (India); Sinha, A. K., E-mail: anil@rrcat.gov.in; Ghosh, Haranath [Indus Synchrotrons Utilization Division, Raja Ramanna Center for Advanced Technology, Indore – 452013 (India); Homi Bhabha National Institute, BARC, Mumbai-400094 (India)

    2015-08-15

    We report anomalous x-ray diffraction studies on Co ferrite with composition Co{sub 1.5}Fe{sub 1.5}O{sub 4} to obtain the distribution of transition metal ions in tetrahedral and octahedral sites. We synthesize spinel oxide (Co{sub 1.5}Fe{sub 1.5}O{sub 4}) through co-precipitation and subsequent annealing route. The imaginary part (absorption) of the energy dependent anomalous form factor is measured and the real part is calculated theoretically through Kramers–Krönig transformation to analyze anomalous x-ray diffraction peak intensities. Fe and Co K-edge x-ray absorption near edge structure (XANES) spectra are used to estimate charge states of transition metals. Our analysis, within experimental errors, suggests 44% of the tetrahedral sites contain Co in +2 oxidation state and the rest 56% sites contain Fe in +2 and +3 oxidation states. Similarly, 47% of the octahedral sites contain Fe in +3 oxidation states, whereas, the rest of the sites contain Co in +2 and +3 oxidation states. While a distinct pre-edge feature in the Fe K-edge XANES is observed, Co pre-edge remains featureless. Implications of these results to magnetism are briefly discussed.

  16. Small angle scattering and polymers

    Energy Technology Data Exchange (ETDEWEB)

    Cotton, J.P. [Laboratoire Leon Brillouin (LLB) - Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)

    1996-12-31

    The determination of polymer structure is a problem of interest for both statistical physics and industrial applications. The average polymer structure is defined. Then, it is shown why small angle scattering, associated with isotopic substitution, is very well suited to the measurement of the chain conformation. The corresponding example is the old, but pedagogic, measurement of the chain form factor in the polymer melt. The powerful contrast variation method is illustrated by a recent determination of the concentration profile of a polymer interface. (author) 12 figs., 48 refs.

  17. X-Rays

    Science.gov (United States)

    X-rays are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of the inside of ... different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat ...

  18. Spectral Softening in the X-Ray Afterglow of GRB 130925A as Predicted by the Dust Scattering Model

    Science.gov (United States)

    Zhao, Yi-Nan; Shao, Lang

    2014-07-01

    Gamma-ray bursts (GRBs) usually occur in a dense star-forming region with a massive circumburst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences and sometimes can dominate the X-ray afterglow. In most of the previous studies, only the Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius of a diffuse interstellar medium. When the size of the grains may significantly increase, as in a more dense region where GRBs would occur, the RG approximation may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculations to understand the puzzling X-ray afterglow of recently observed GRB 130925A that showed a significant spectral softening. We find that the X-ray scattering scenarios with either AD or RG approximation adopted could well reproduce both the temporal and spectral profile simultaneously. Given the plateau present in the early X-ray light curve, a typical distribution of smaller grains as in the interstellar medium would be suggested for GRB 130925A.

  19. Chest x-ray

    Science.gov (United States)

    Chest radiography; Serial chest x-ray; X-ray - chest ... You stand in front of the x-ray machine. You will be told to hold your breath when the x-ray is taken. Two images are usually taken. You will ...

  20. Different approaches to the analysis of small angle scattering experiments on porous aluminum-hydroxide

    DEFF Research Database (Denmark)

    Rasmussen, F.B.

    2001-01-01

    Different approaches to the analysis of Small Angle X-ray Scattering experiments on the porous aluminum-hydroxide pseudo-boehmite are compared. Experimental data is analyzed both as scattering from mass fractal aggregates and polydisperse collections of anisotropic particles. Both types of analys...

  1. The study of pinch regimes based on radiation-enhanced compression and anomalous resistivity phenomena and their effects on hard x-ray emission in a Mather type dense plasma focus device (SABALAN2)

    International Nuclear Information System (INIS)

    In this study, by using argon and nitrogen as the filling gases in a Mather type dense plasma focus device at different values of pressure and charging voltage, two different kinds of pinch regimes were observed for each of the gases. The physics of the pinch regimes could be explained by using the two versions of the Lee's computational model which predicted each of the scenarios and clarified their differences between the two gases according to the radiation-enhanced compression and, additionally, predicted the pinch regimes through the anomalous resistivity effect during the pinch time. This was accomplished through the fitting process (simulation) on the current signal. Moreover, the characteristic amplitude and time scales of the anomalous resistances were obtained. The correlations between the features of the plasma current dip and the emitted hard x-ray pulses were observed. The starting time, intensity, duration, and the multiple or single feature of the emitted hard x-ray strongly correlated to the same respective features of the current dip

  2. The study of pinch regimes based on radiation-enhanced compression and anomalous resistivity phenomena and their effects on hard x-ray emission in a Mather type dense plasma focus device (SABALAN2)

    Science.gov (United States)

    Piriaei, D.; Mahabadi, T. D.; Javadi, S.; Ghoranneviss, M.; Saw, S. H.; Lee, S.

    2015-12-01

    In this study, by using argon and nitrogen as the filling gases in a Mather type dense plasma focus device at different values of pressure and charging voltage, two different kinds of pinch regimes were observed for each of the gases. The physics of the pinch regimes could be explained by using the two versions of the Lee's computational model which predicted each of the scenarios and clarified their differences between the two gases according to the radiation-enhanced compression and, additionally, predicted the pinch regimes through the anomalous resistivity effect during the pinch time. This was accomplished through the fitting process (simulation) on the current signal. Moreover, the characteristic amplitude and time scales of the anomalous resistances were obtained. The correlations between the features of the plasma current dip and the emitted hard x-ray pulses were observed. The starting time, intensity, duration, and the multiple or single feature of the emitted hard x-ray strongly correlated to the same respective features of the current dip.

  3. The study of pinch regimes based on radiation-enhanced compression and anomalous resistivity phenomena and their effects on hard x-ray emission in a Mather type dense plasma focus device (SABALAN2)

    Energy Technology Data Exchange (ETDEWEB)

    Piriaei, D.; Javadi, S.; Ghoranneviss, M. [Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran 1477893855 (Iran, Islamic Republic of); Mahabadi, T. D., E-mail: tadavari@gmail.com [Department of Physics and Biophysics, Tehran Medical Sciences Branch, Islamic Azad University, Tehran 1916893813 (Iran, Islamic Republic of); Saw, S. H. [INTI International University, Nilai 71800 (Malaysia); Institute for Plasma Focus Studies, 32 Oak Park Drive, Victoria 3148 (Australia); Lee, S. [INTI International University, Nilai 71800 (Malaysia); Institute for Plasma Focus Studies, 32 Oak Park Drive, Victoria 3148 (Australia); Universty of Malaya, Kuala Lumpur 50603 (Malaysia)

    2015-12-15

    In this study, by using argon and nitrogen as the filling gases in a Mather type dense plasma focus device at different values of pressure and charging voltage, two different kinds of pinch regimes were observed for each of the gases. The physics of the pinch regimes could be explained by using the two versions of the Lee's computational model which predicted each of the scenarios and clarified their differences between the two gases according to the radiation-enhanced compression and, additionally, predicted the pinch regimes through the anomalous resistivity effect during the pinch time. This was accomplished through the fitting process (simulation) on the current signal. Moreover, the characteristic amplitude and time scales of the anomalous resistances were obtained. The correlations between the features of the plasma current dip and the emitted hard x-ray pulses were observed. The starting time, intensity, duration, and the multiple or single feature of the emitted hard x-ray strongly correlated to the same respective features of the current dip.

  4. Thoracic spine x-ray

    Science.gov (United States)

    Vertebral radiography; X-ray - spine; Thoracic x-ray; Spine x-ray; Thoracic spine films; Back films ... care provider's office. You will lie on the x-ray table in different positions. If the x-ray ...

  5. Proceedings of the International school and symposium on small angle scattering

    International Nuclear Information System (INIS)

    The meeting was devoted to small angle neutron and X-ray scattering with regard to the wide interest for this method in various fields of basic and applied research. Scientists from European laboratories gave introductory talks to various subject fields related to small angle scattering (SAS) techniques or data analysis methods as well as topical research area e.g. soft condensed matter, biology or materials science. An important number of contributed talks were presented on neutron or X-ray scattering and even on combining both of them, demonstrating the very useful complementarity of these methods. Some other papers give nice examples of SAS experiments completed by results of other techniques such as NMRE of light scattering. The variety of presented contributions is a nice demonstration for the interdisciplinary use of small angle scattering from physics through biology, chemistry, materials science to engineering. 18 items are indexed separately for the INIS database. (K.A.)

  6. X-ray (image)

    Science.gov (United States)

    X-rays are a form of ionizing radiation that can penetrate the body to form an image on ... will be shades of gray depending on density. X-rays can provide information about obstructions, tumors, and other ...

  7. Dental x-rays

    Science.gov (United States)

    X-ray - teeth; Radiograph - dental; Bitewings; Periapical film; Panoramic film ... dentist's office. There are many types of dental x-rays. Some are: Bitewing Periapical Palatal (also called occlusal) ...

  8. X-ray apparatus

    International Nuclear Information System (INIS)

    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

  9. Dental x-rays

    Science.gov (United States)

    X-ray - teeth; Radiograph - dental; Bitewings; Periapical film; Panoramic film; Digital image ... dentist's office. There are many types of dental x-rays. Some of them are: Bitewing. Shows the crown ...

  10. X-Rays

    Science.gov (United States)

    X-rays are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of the inside of your ... different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat and ...

  11. Chest X-Ray

    Medline Plus

    Full Text Available ... by: Image/Video Gallery Your radiologist explains chest x-ray. Transcript Welcome to Radiology Info dot org! Hello, ... you about chest radiography also known as chest x-rays. Chest x-rays are the most commonly performed ...

  12. X-Ray Imaging

    Science.gov (United States)

    ... Brain Surgery Imaging Clinical Trials Basics Patient Information X-Ray Imaging Print This Page X-ray imaging is perhaps the most familiar type of imaging. Images produced by X-rays are due to the different absorption rates of ...

  13. Theoretical analysis on x-ray cylindrical grating interferometer

    OpenAIRE

    Cong, Wenxiang; Xi, Yan; Wang, Ge

    2015-01-01

    Grating interferometer is a state of art x-ray imaging approach, which can simultaneously acquire information of x-ray attenuation, phase shift, and small angle scattering. This approach is very sensitive to micro-structural variation and offers superior contrast resolution for biological soft tissues. The present grating interferometer often uses flat gratings, with serious limitations in the field of view and the flux of photons. The use of curved gratings allows perpendicular incidence of ...

  14. Crystallization and X-ray diffraction analysis of a novel immune-type receptor from Ictalurus punctatus and phasing by selenium anomalous dispersion methods

    International Nuclear Information System (INIS)

    A highly diversified novel immune-type receptor from catfish, NITR10, was crystallized to reveal novel mechanisms of immune recognition. X-ray diffraction data from crystals of a novel immune-type receptor (NITR10 from the catfish Ictalurus punctatus) were collected to 1.65 Å resolution and reduced to the primitive hexagonal lattice. Native and selenomethionine derivatives of NITR10 crystallized under different conditions yielded P3121 crystals. SeMet NITR10 was phased to a correlation coefficient of 0.77 by SAD methods and experimental electron-density maps were calculated to 1.65 Å. Five NITR10 molecules are predicted to be present in the asymmetric unit based on the Matthews coefficient

  15. Burst and Persistent Emission Properties during the Recent Active Episode of the Anomalous X-Ray Pulsar 1E 1841-045

    Science.gov (United States)

    Lin, Lin; Kouveliotou, Chryssa; Gogus, Ersin; van der Horst, Alexander J.; Watts, Anna L.; Baring, Matthew G.; Kaneko, Yuki; Wijers, Ralph A. M. J.; Woods, Peter M.; Barthelmy, Scott; Burgess, J. Michael; Chaplin, Vandiver; Gehrels, Neil; Goldstein, Adam; Granot, Jonathan; Guiriec, Sylvain; Mcenery, Julie; Preece, Robert D.; Tierney, David; van der Klis, Michiel; von Kienlin, Andreas; Zhang, Shuang Nan

    2011-01-01

    SWift/BAT detected the first burst from 1E 1841-045 in May 2010 with intermittent burst activity recorded through at least July 2011. Here we present Swift and Fermi/GBM observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T90 durations of the bursts range between 18 - 140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8-25) x 1038 erg, which is in the low side of SGR bursts. We find that the bursting activity did not have a significant effect on the persistent flux level of the source. We argue that the mechanism leading to this sporadic burst activity in IE 1841-045 might not involve large scale restructuring (either crustal or magnetospheric) as seen in other magnetar sources.

  16. Local structure around Pd atoms in Pd42.5Ni7.5Cu30P20 excellent glass-former studied by anomalous X-ray scattering

    International Nuclear Information System (INIS)

    In order to study local structure around the Pd atoms in Pd42.5Ni7.5Cu30P20 excellent metallic glass-former, an anomalous X-ray scattering (AXS) experiment was performed at energies close to the Pd K absorption edge at the beamline BM02 of the European Synchrotron Radiation Facility. The differential structure factor, ΔPdS(Q), was obtained with a good statistical quality, which demonstrates that a pre-shoulder at about 20nm-1, indicating the existence of an intermediate-range order, originates from the Pd-Pd atomic correlation. The first peak in the differential pair correlation function, ΔPdg(r), shows a longer inter-atomic length around the Pd atoms than the average value. The local structure around the Pd atoms is discussed in detail by comparing to the previous experiments of AXS and electronic structure. (author)

  17. Small-angle neutron scattering instrument at MINT

    International Nuclear Information System (INIS)

    The Small Angle Neutron Scattering (SANS) Instrument has been developed at Malaysian Institute for Nuclear Technology Research (MINT) for studying structural properties of materials on the length scale 1 nm to 100 nm. This is the length scale which is relevant for many topics within soft condensed matter, like polymers, colloids, biological macromolecules, etc. The SANS is a complementary technique to X-ray and electron scattering. However, while these later techniques give information on structures near surface, SANS concerns the structure of the bulk. Samples studied by SANS technique are typically bulk materials of the sizes mm's to cm's, or materials dissolved in a liquid. This paper described the general characteristics of SANS instrument as well as the experimental formulation in neutron scattering. The preliminary results obtained by this instrument are shown

  18. X-Ray Polarimetry

    CERN Document Server

    Kaaret, Philip

    2014-01-01

    We review the basic principles of X-ray polarimetry and current detector technologies based on the photoelectric effect, Bragg reflection, and Compton scattering. Recent technological advances in high-spatial-resolution gas-filled X-ray detectors have enabled efficient polarimeters exploiting the photoelectric effect that hold great scientific promise for X-ray polarimetry in the 2-10 keV band. Advances in the fabrication of multilayer optics have made feasible the construction of broad-band soft X-ray polarimeters based on Bragg reflection. Developments in scintillator and solid-state hard X-ray detectors facilitate construction of both modular, large area Compton scattering polarimeters and compact devices suitable for use with focusing X-ray telescopes.

  19. Resonant X-ray emission with a standing wave excitation.

    Science.gov (United States)

    Ruotsalainen, Kari O; Honkanen, Ari-Pekka; Collins, Stephen P; Monaco, Giulio; Moretti Sala, Marco; Krisch, Michael; Hämäläinen, Keijo; Hakala, Mikko; Huotari, Simo

    2016-01-01

    The Borrmann effect is the anomalous transmission of x-rays in perfect crystals under diffraction conditions. It arises from the interference of the incident and diffracted waves, which creates a standing wave with nodes at strongly absorbing atoms. Dipolar absorption of x-rays is thus diminished, which makes the crystal nearly transparent for certain x-ray wave vectors. Indeed, a relative enhancement of electric quadrupole absorption via the Borrmann effect has been demonstrated recently. Here we show that the Borrmann effect has a significantly larger impact on resonant x-ray emission than is observable in x-ray absorption. Emission from a dipole forbidden intermediate state may even dominate the corresponding x-ray spectra. Our work extends the domain of x-ray standing wave methods to resonant x-ray emission spectroscopy and provides means for novel spectroscopic experiments in d- and f-electron systems.

  20. Resonant X-ray emission with a standing wave excitation

    Science.gov (United States)

    Ruotsalainen, Kari O.; Honkanen, Ari-Pekka; Collins, Stephen P.; Monaco, Giulio; Moretti Sala, Marco; Krisch, Michael; Hämäläinen, Keijo; Hakala, Mikko; Huotari, Simo

    2016-01-01

    The Borrmann effect is the anomalous transmission of x-rays in perfect crystals under diffraction conditions. It arises from the interference of the incident and diffracted waves, which creates a standing wave with nodes at strongly absorbing atoms. Dipolar absorption of x-rays is thus diminished, which makes the crystal nearly transparent for certain x-ray wave vectors. Indeed, a relative enhancement of electric quadrupole absorption via the Borrmann effect has been demonstrated recently. Here we show that the Borrmann effect has a significantly larger impact on resonant x-ray emission than is observable in x-ray absorption. Emission from a dipole forbidden intermediate state may even dominate the corresponding x-ray spectra. Our work extends the domain of x-ray standing wave methods to resonant x-ray emission spectroscopy and provides means for novel spectroscopic experiments in d- and f-electron systems. PMID:26935531

  1. X-Ray Polarimetry

    OpenAIRE

    Kaaret, Philip

    2014-01-01

    We review the basic principles of X-ray polarimetry and current detector technologies based on the photoelectric effect, Bragg reflection, and Compton scattering. Recent technological advances in high-spatial-resolution gas-filled X-ray detectors have enabled efficient polarimeters exploiting the photoelectric effect that hold great scientific promise for X-ray polarimetry in the 2-10 keV band. Advances in the fabrication of multilayer optics have made feasible the construction of broad-band ...

  2. Characterization of porous materials by small-angle scattering

    Indian Academy of Sciences (India)

    S Mazumder; D Sen; A K Patra

    2004-07-01

    Characterization of porous materials by small-angle scattering has been extensively pursued for several years now as the pores are often of mesoscopic size and compatible with the length scale accessible by the technique using both neutrons and X-rays as probing radiation. With the availability of ultra small-angle scattering instruments, one can investigate porous materials in the sub-micron length scale. Because of the increased accessible length scale vis-a-vis the multiple scattering effect, conventional data analysis procedures based on single scattering approximation quite often fail. The limitation of conventional data analysis procedures is also pronounced in the case of thick samples and long wavelength of the probing radiation. Effect of multiple scattering is manifested by broadening the scattering profile. Sample thickness for some technologically important materials is often significantly high, as the experimental samples have to replicate all its essential properties in the bulk material. Larger wavelength of the probing radiation is used in some cases to access large length scale and also to minimize the effect of double Bragg reflections.

  3. Use of anomalous scattering for synchrotron X-ray reflectivity studies of Fe-Cr and Co-Cu double layers

    CERN Document Server

    Prokert, F; Gorbunov, A

    2003-01-01

    Double layers of Fe-Cr and Co-Cu, respectively, were prepared on oxidized Si substrates by pulsed laser deposition (PLD). The interfacial roughness structure was studied by synchrotron X-ray reflectivity measurements at the absorption K-edges using the contrast enhancement due to resonant scattering. The results are determined from simulations of the measured specular and diffuse scans. Whereas in Fe-Cr double layers the sigma sub r sub m sub s -interface width for Fe deposition on Cr (sigma sub C sub r =0.70+-0.1 nm) is not very different from that of Cr deposition on Fe (sigma sub F sub e =0.85+-0.1 nm), in Co-Cu double layers, in contrast, for Cu deposition on Co, the width (sigma sub C sub o =0.65+-0.1 nm) is much smaller than for Co deposition on Cu (sigma sub C sub u =1.5+-0.15 nm). On the basis of the fractal model to describe the interface roughness morphology, from the off-specular scans the lateral roughness correlation length, xi and the roughness exponent, h, were determined. For both types of dou...

  4. RXTE Observations of Anomalous X-ray Pulsar 1E 1547.0-5408 During and After its 2008 and 2009 Outbursts

    CERN Document Server

    Dib, Rim; Scholz, Paul; Gavriil, Fotis P

    2012-01-01

    We present the results of Rossi X-ray Timing Explorer (RXTE) and Swift monitoring observations of the magnetar 1E 1547.0-5408 following the pulsar's radiative outbursts in 2008 October and 2009 January. We report on a study of the evolution of the timing properties and the pulsed flux from 2008 October 4 through 2009 December 26. We show that the pulsed flux decrease which followed an initial rise in the 2008 outburst was interrupted by a spike ~9 days after the initial outburst. In our timing study, a phase-coherent analysis shows that for the first 29 days following the 2008 outburst, there was a very fast increase in the magnitude of the rotational frequency derivative nudot, such that the second derivative was a factor of ~60 larger than that reported in data from 2007. This nudot magnitude increase occurred in concert with the decay of the pulsed flux following the start of the 2008 event. Following the 2009 outburst, for the first 23 days, the second derivative was consistent with zero, and nudot had re...

  5. Modeling the amorphous structure of mechanically alloyed Ti{sub 50}Ni{sub 25}Cu{sub 25} using anomalous wide-angle x-ray scattering and reverse Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lima, J.C. de, E-mail: fsc1jcd@fisica.ufsc.br [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Poffo, C.M. [Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Souza, S.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Machado, K.D. [Departamento de Física, Centro Politécnico, Universidade Federal do Paraná, 81531-990 Curitiba, Paraná (Brazil); Trichês, D.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Grandi, T.A. [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Biasi, R.S. de [Seção de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

    2013-09-01

    An amorphous Ti{sub 50}Ni{sub 25}Cu{sub 25} alloy was produced by 19 h of mechanical alloying. Anomalous wide angle x-ray scattering data were collected at six energies and six total scattering factors were obtained. By considering the data collected at two energies close to the Ni and Cu K edges, two differential anomalous scattering factors about the Ni and Cu atoms were obtained, showing that the chemical environments around these atoms are different. Eight factors were used as input data to the reverse Monte Carlo method used to compute the partial structure factors S{sub Ti3Ti}(K), S{sub Ti–Cu}(K), S{sub Ti–Ni}(K), S{sub Cu3Cu}(K), S{sub Cu–Ni}(K) and S{sub Ni–Ni}(K) and the partial pair distribution functions G{sub Ti3Ti}(r), G{sub Ti–Cu}(r), G{sub Ti–Ni}(r), G{sub Cu3Cu}(r), G{sub Cu–Ni}(r) and G{sub Ni–Ni}(r). From the RMC final atomic configuration and G{sub ij}(r) functions, the coordination numbers and interatomic atomic distances for the first neighbors were determined.

  6. X-ray crystallographic studies of metalloproteins.

    Science.gov (United States)

    Volbeda, Anne

    2014-01-01

    Many proteins require metals for their physiological function. In combination with spectroscopic characterizations, X-ray crystallography is a very powerful method to correlate the function of protein-bound metal sites with their structure. Due to their special X-ray scattering properties, specific metals may be located in metalloprotein structures and eventually used for phasing the diffracted X-rays by the method of Multi-wavelength Anomalous Dispersion (MAD). How this is done is the principle subject of this chapter. Attention is also given to the crystallographic characterization of different oxidation states of redox active metals and to the complication of structural changes that may be induced by X-ray irradiation of protein crystals.

  7. Insights from soft X-rays

    DEFF Research Database (Denmark)

    Raaf, Jennifer; Issinger, Olaf-Georg; Niefind, Karsten

    2008-01-01

    The diffraction pattern of a protein crystal is normally a product of the interference of electromagnetic waves scattered by electrons of the crystalline sample. The diffraction pattern undergoes systematic changes in case additionally X-ray absorption occurs, meaning if the wavelength of the pri......The diffraction pattern of a protein crystal is normally a product of the interference of electromagnetic waves scattered by electrons of the crystalline sample. The diffraction pattern undergoes systematic changes in case additionally X-ray absorption occurs, meaning if the wavelength...... of the primary X-ray beam is relatively close to the absorption edge of selected elements of the sample. The resulting effects are summarized as "anomalous dispersion" and can be always observed with "soft" X-rays (wavelength around 2 A) since they match the absorption edges of sulfur and chlorine...

  8. X-ray - skeleton

    Science.gov (United States)

    A skeletal x-ray is an imaging test used to look at the bones. It is used to detect fractures , tumors, or ... in the health care provider's office by an x-ray technologist. You will lie on a table or ...

  9. Extremity x-ray

    Science.gov (United States)

    An extremity x-ray is an image of the hands, wrist, feet, ankle, leg, thigh, forearm humerus or upper arm, hip, shoulder ... term "extremity" often refers to a human limb. X-rays are a form of radiation that passes through ...

  10. X-ray interferometers

    International Nuclear Information System (INIS)

    An improved type of amplitude-division x-ray interferometer is described. The wavelength at which the interferometer can operate is variable, allowing the instrument to be used to measure x-ray wavelength, and the angle of inclination is variable for sample investigation. (U.K.)

  11. An efficient parallel GPU evaluation of small angle x-ray scattering profiles

    DEFF Research Database (Denmark)

    Antonov, Lubomir Dimitrov; Andreetta, Christian; Hamelryck, Thomas Wim

    The inference of protein structure from experimental data is of crucial interest in science, medicine and biotechnology. Unfortunately, high-resolution experimental methods can not yet provide a detailed analysis of the ensemble of conformations adopted under physiological conditions. Low...... in humans. In silico simulations can bridge the gap between low resolution information and models derived from high-resolution techniques. For that, it is necessary to be able to calculate the low resolution information from a given detailed model using a so-called forward model. These calculations need...... of magnitude faster than an efficient CPU implementation, and implements a caching procedure ready to be employed in the partial SAXS evaluations required by in silico simulations....

  12. SFF analysis of the small angle scattering data for investigation of a vesicle systems structure

    Science.gov (United States)

    Zemlyanaya, E. V.; Kiselev, M. A.; Zhabitskaya, E. I.; Gruzinov, A. Yu.; Aksenov, V. L.; Ipatova, O. M.; Druzhilovskaya, O. S.

    2016-06-01

    Experimental data on the small angle synchrotron X-ray scattering (SAXS) are analyzed on a basis of Separated form factors method (SFF) for a study of the drug delivery Phospholipid Transport Nano System (PTNS). Basic parameters of polydispersed population of PTNS nanoparticles (average radius of PTNS-particles, polydispersity of radius, thickness of membrane) have been determined. The results are discussed in comparison with the SFF results for the “classical” vesicular system of dimyristoylphosphocholine (DMPC).

  13. Lensless x-ray imaging in reflection geometry

    Energy Technology Data Exchange (ETDEWEB)

    Roy, S.; Parks, D.H.; Seu, K.A.; Turner, J.J.; Chao, W.; Anderson, E.H.; Cabrini, S.; Kevan, S.D.; Su, R.

    2011-02-03

    Lensless X-ray imaging techniques such as coherent diffraction imaging and ptychography, and Fourier transform holography can provide time-resolved, diffraction-limited images. Nearly all examples of these techniques have focused on transmission geometry, restricting the samples and reciprocal spaces that can be investigated. We report a lensless X-ray technique developed for imaging in Bragg and small-angle scattering geometries, which may also find application in transmission geometries. We demonstrate this by imaging a nanofabricated pseudorandom binary structure in small-angle reflection geometry. The technique can be used with extended objects, places no restriction on sample size, and requires no additional sample masking. The realization of X-ray lensless imaging in reflection geometry opens up the possibility of single-shot imaging of surfaces in thin films, buried interfaces in magnetic multilayers, organic photovoltaic and field-effect transistor devices, or Bragg planes in a single crystal.

  14. Modelling small-angle scattering data from complex protein-lipid systems

    DEFF Research Database (Denmark)

    Kynde, Søren Andreas Røssell

    are particularly interesting to study because they are common targets for pharmaceutical drugs. At the same time they are unfortunately unstable in solution which make them challenging to study. Phospholipid nanodiscs are small patches of lipid membrane stabilised by a belt of amphipathic helices. They can act...... as carriers of membrane proteins. Together they form monodisperse soluble aggregates of about 10 nm in size. Chapter 2 introduces the method of small-angle scattering. Small-angle X-ray and neutron scattering are well suited for studying particles in solution on length scales from 1 to 100 nm. This makes...... combine the bene ts of each of the methods and give unique structural information about relevant bio-molecular complexes in solution. Chapter 4 describes the work behind a proposal of a small-angle neutron scattering instrument for the European Spallation Source under construction in Lund. The instrument...

  15. Small Angle Light Scattering by Biological Objects

    International Nuclear Information System (INIS)

    In this paper the small angle laser radiation scattering by the particles of different shape and size is analyzed. Experimental results and theoretical calculations show that after ejection from bacteriophage DNA forms the scattering medium consisted of quasi-spherical elements with radius of R⁓10λ0. (author)

  16. Status of the CDF small angle spectrometer

    International Nuclear Information System (INIS)

    During the 1987 Tevatron collider period the CDF small angle spectrometer system was partially installed and elastic scattering events were recorded in a special high-β run. The design and physics goals of this system are described and results from an analysis of the elastic scattering data are discussed

  17. 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.

  18. Phase-contrast X-ray imaging of breast

    Energy Technology Data Exchange (ETDEWEB)

    Keyrilaeinen, Jani; Tenhunen, Mikko (Dept. of Physics, HUCH Cancer Center, Helsinki Univ. Central Hospital, Helsinki (Finland)), e-mail: jani.keyrilainen@hus.fi; Bravin, Alberto (Bio-medical Beamline ID17, European Synchrotron Radiation Facility, Grenoble (France)); Fernandez, Manuel (High Brilliance Beamline ID2, European Synchrotron Radiation Facility, Grenoble (France)); Virkkunen, Pekka (Dept. of Radiology, HUCH Cancer Center, Helsinki Univ. Central Hospital, Helsinki (Finland)); Suortti, Pekka (Dept. of Physics, Univ. of Helsinki, Helsinki (Finland))

    2010-10-15

    When an X-ray wave traverses an object, its amplitude and phase change, resulting in attenuation, interference, and refraction, and in phase-contrast X-ray imaging (PCI) these are converted to intensity changes. The relative change of the X-ray phase per unit path length is even orders of magnitude larger than that of the X-ray amplitude, so that the image contrast based on variation of the X-ray phase is potentially much stronger than the contrast based on X-ray amplitude (absorption contrast). An important medical application of PCI methods is soft-tissue imaging, where the absorption contrast is inherently weak. It is shown by in vitro examples that signs of malignant human breast tumor are enhanced in PCI images. Owing to the strong contrast, the radiation dose can be greatly reduced, so that a high-resolution phase-contrast X-ray tomography of the breast is possible with about 1 mGy mean glandular dose. Scattered radiation carries essential information on the atomic and molecular structure of the object, and particularly small-angle X-ray scattering can be used to trace cancer. The imaging methods developed at the synchrotron radiation facilities will become available in the clinical environment with the ongoing development of compact radiation sources, which produce intense X-ray beams of sufficient coherence. Several developments that are under way are described here

  19. Phase-contrast X-ray imaging of breast.

    Science.gov (United States)

    Keyriläinen, Jani; Bravin, Alberto; Fernández, Manuel; Tenhunen, Mikko; Virkkunen, Pekka; Suortti, Pekka

    2010-10-01

    When an X-ray wave traverses an object, its amplitude and phase change, resulting in attenuation, interference, and refraction, and in phase-contrast X-ray imaging (PCI) these are converted to intensity changes. The relative change of the X-ray phase per unit path length is even orders of magnitude larger than that of the X-ray amplitude, so that the image contrast based on variation of the X-ray phase is potentially much stronger than the contrast based on X-ray amplitude (absorption contrast). An important medical application of PCI methods is soft-tissue imaging, where the absorption contrast is inherently weak. It is shown by in vitro examples that signs of malignant human breast tumor are enhanced in PCI images. Owing to the strong contrast, the radiation dose can be greatly reduced, so that a high-resolution phase-contrast X-ray tomography of the breast is possible with about 1 mGy mean glandular dose. Scattered radiation carries essential information on the atomic and molecular structure of the object, and particularly small-angle X-ray scattering can be used to trace cancer. The imaging methods developed at the synchrotron radiation facilities will become available in the clinical environment with the ongoing development of compact radiation sources, which produce intense X-ray beams of sufficient coherence. Several developments that are under way are described here. PMID:20799921

  20. Soft X-ray multilayers and filters

    CERN Document Server

    Wang Zhan Shan; Tang Wei Xing; Qin Shuji; Zhou Bing; Chen Ling Ya

    2002-01-01

    The periodic and non-periodic multilayers were designed by using a random number to change each layer and a suitable merit function. Ion beam sputtering and magnetron sputtering were used to fabricate various multilayers and beam splitters in soft X-ray range. The characterization of multilayers by small angle X-ray diffraction, Auger electron spectroscopy, Rutherford back scattering spectroscopy and reflectivity illustrated the multilayers had good structures and smooth interlayers. The reflectivity and transmission of a beam splitter is about 5%. The fabrication and transmission properties of Ag, Zr were studied. The Rutherford back scattering spectroscopy and auger electron spectroscopy were used to investigate the contents and distributions of impurities and influence on qualities of filters. The attenuation coefficients were corrected by the data obtained by measurements

  1. Delayed X-Ray Afterglows from Obscured Gamma-Ray Bursts in Star-Forming Regions

    OpenAIRE

    Meszaros, P.; Gruzinov, A.

    2000-01-01

    For Gamma-Ray Bursts occurring in dense star-forming regions, the X-ray afterglow behavior minutes to days after the trigger may be dominated by the small-angle scattering of the prompt X-ray emission off dust grains. We give a simple illustrative model for the X-ray light curves at different X-ray energies, and discuss possible implications. A bump followed by a steeper decay in soft X-rays is predicted for bursts which are heavily obscured in the optical.

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Resources Professions Site Index A-Z X-ray (Radiography) - Bone Bone x-ray uses a very small ... X-ray (Radiography)? What is Bone X-ray (Radiography)? An x-ray (radiograph) is a noninvasive medical ...

  3. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Professions Site Index A-Z X-ray (Radiography) - Bone Bone x-ray uses a very small dose ... limitations of Bone X-ray (Radiography)? What is Bone X-ray (Radiography)? An x-ray (radiograph) is ...

  4. Lumbosacral spine x-ray

    Science.gov (United States)

    X-ray - lumbosacral spine; X-ray - lower spine ... The test is done in a hospital x-ray department or your health care provider's office by an x-ray technician. You will be asked to lie on the x-ray table ...

  5. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Bone Bone x-ray uses a very ... of Bone X-ray (Radiography)? What is Bone X-ray (Radiography)? An x-ray (radiograph) is a noninvasive ...

  6. Abdomen X-Ray (Radiography)

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Abdomen Abdominal x-ray uses a very ... of an abdominal x-ray? What is abdominal x-ray? An x-ray (radiograph) is a noninvasive medical ...

  7. X-ray lasers

    CERN Document Server

    Elton, Raymond C

    2012-01-01

    The first in its field, this book is both an introduction to x-ray lasers and a how-to guide for specialists. It provides new entrants and others interested in the field with a comprehensive overview and describes useful examples of analysis and experiments as background and guidance for researchers undertaking new laser designs. In one succinct volume, X-Ray Lasers collects the knowledge and experience gained in two decades of x-ray laser development and conveys the exciting challenges and possibilities still to come._Add on for longer version of blurb_M>The reader is first introduced

  8. X-Ray Diffraction.

    Science.gov (United States)

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  9. Medical X-Rays

    Science.gov (United States)

    ... The Conference of Radiation Control Program Directors (CRCPD) publishes Suggested State Regulations for the Control of Radiation , ... eSubmitter Guidance for Industry and Food and Drug Administration Staff - Assembler's Guide to Diagnostic X-Ray Equipment ...

  10. Chest X-Ray

    Medline Plus

    Full Text Available ... However, it’s important to consider the likelihood of benefit to your health. While a chest x-ray use a tiny dose of ionizing radiation, the benefit of an accurate diagnosis far outweighs any risk. ...

  11. Chest X-Ray

    Medline Plus

    Full Text Available ... chest x-ray is used to evaluate the lungs, heart and chest wall and may be used ... diagnose and monitor treatment for a variety of lung conditions such as pneumonia, emphysema and cancer. A ...

  12. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... drawer under the table holds the x-ray film or image recording plate . Sometimes the x-ray ... extended over the patient while an x-ray film holder or image recording plate is placed beneath ...

  13. The small angle diffractometer SANS at PSI

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1996-11-01

    With the start-up of SINQ an instrument for small angle neutron scattering will be operational which compares well with the world`s largest and most powerful facilities of this kind. Following the classical principle of the D11-instrument of ILL, it is equipped with state-of-the-art components as are nowadays available, including options for further upgrading. Great emphasis was laid upon providing a flexible, universal multi-user facility which guarantees a comfortable and reliable operation. In the present paper, the principle layout of the instrument is presented, and the individual components are described in detail. The paper concludes with model application of small angle scattering to a system of dilute CuCo alloys which undergo a phase separation under thermal treatment, forming spherical Co-precipitates dispersed in a Cu-rich matrix. (author) 3 figs., 1 tab., 14 refs.

  14. Fractal Approach in Petrology: Combining Ultra-Small Angle (USANA) and Small Angle Neutron Scattering (SANS)

    Energy Technology Data Exchange (ETDEWEB)

    LoCelso, F.; Triolo, F.; Triolo, A.; Lin, J.S.; Lucido, G.; Triolo, R.

    1999-10-14

    Ultra small angle neutron scattering instruments have recently covered the gap between the size resolution available with conventional intermediate angle neutron scattering and small angle neutron scattering instruments on one side and optical microscopy on the other side. Rocks showing fractal behavior in over two decades of momentum transfer and seven orders of magnitude of intensity are examined and fractal parameters are extracted from the combined USANS and SANS curves.

  15. Anomalous lattice expansion in yttria stabilized zirconia under simultaneous applied electric and thermal fields: A time-resolved in situ energy dispersive x-ray diffractometry study with an ultrahigh energy synchrotron probe

    Energy Technology Data Exchange (ETDEWEB)

    Akdogan, E. K.; Savkl Latin-Small-Letter-Dotless-I y Latin-Small-Letter-Dotless-I ld Latin-Small-Letter-Dotless-I z, I.; Bicer, H.; Paxton, W.; Toksoy, F.; Tsakalakos, T. [Department of Materials Science and Engineering, Rutgers University, Piscataway, New Jersey 08854-8065 (United States); Zhong, Z. [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2013-06-21

    Nonisothermal densification in 8% yttria doped zirconia (8YSZ) particulate matter of 250 nm median particle size was studied under 215 V/cm dc electric field and 9 Degree-Sign C/min heating rate, using time-resolved in-situ high temperature energy dispersive x-ray diffractometry with a polychromatic 200 keV synchrotron probe. Densification occurred in the 876-905 Degree-Sign C range, which resulted in 97% of the theoretical density. No local melting at particle-particle contacts was observed in scanning electron micrographs, implying densification was due to solid state mass transport processes. The maximum current draw at 905 Degree-Sign C was 3 A, corresponding to instantaneous absorbed power density of 570 W/cm{sup 3}. Densification of 8YSZ was accompanied by anomalous elastic volume expansions of the unit cell by 0.45% and 2.80% at 847 Degree-Sign C and 905 Degree-Sign C, respectively. The anomalous expansion at 905 Degree-Sign C at which maximum densification was observed is characterized by three stages: (I) linear stage, (II) anomalous stage, and (III) anelastic recovery stage. The densification in stage I (184 s) and II (15 s) was completed in 199 s, while anelastic relaxation in stage III lasted 130 s. The residual strains ({epsilon}) at room temperature, as computed from tetragonal (112) and (211) reflections, are {epsilon}{sub (112)} = 0.05% and {epsilon}{sub (211)} = 0.13%, respectively. Time dependence of (211) and (112) peak widths ({beta}) show a decrease with both exhibiting a singularity at 905 Degree-Sign C. An anisotropy in (112) and (211) peak widths of {l_brace} {beta}{sub (112)}/{beta}{sub (211)}{r_brace} = (3:1) magnitude was observed. No phase transformation occurred at 905 Degree-Sign C as verified from diffraction spectra on both sides of the singularity, i.e., the unit cell symmetry remains tetragonal. We attribute the reduction in densification temperature and time to ultrafast ambipolar diffusion of species arising from the

  16. X-ray Pulsars

    CERN Document Server

    Walter, Roland

    2016-01-01

    X-ray pulsars shine thanks to the conversion of the gravitational energy of accreted material to X-ray radiation. The accretion rate is modulated by geometrical and hydrodynamical effects in the stellar wind of the pulsar companions and/or by instabilities in accretion discs. Wind driven flows are highly unstable close to neutron stars and responsible for X-ray variability by factors $10^3$ on time scale of hours. Disk driven flows feature slower state transitions and quasi periodic oscillations related to orbital motion and precession or resonance. On shorter time scales, and closer to the surface of the neutron star, X-ray variability is dominated by the interactions of the accreting flow with the spinning magnetosphere. When the pulsar magnetic field is large, the flow is confined in a relatively narrow accretion column, whose geometrical properties drive the observed X-ray emission. In low magnetized systems, an increasing accretion rate allows the ignition of powerful explosive thermonuclear burning at t...

  17. X-ray astronomy

    International Nuclear Information System (INIS)

    This book contains the lectures, and the most important seminars held at the NATO meeting on X-Ray astronomy in Erice, July 1979. The meeting was an opportune forum to discuss the results of the first 8-months of operation of the X-ray satellite, HEAO-2 (Einstein Observatory) which was launched at the end of 1978. Besides surveying these results, the meeting covered extragalactic astronomy, including the relevant observations obtained in other portions of the electromagnetic spectrum (ultra-violet, optical, infrared and radio). The discussion on galactic X-ray sources essentially covered classical binaries, globular clusters and bursters and its significance to extragalactic sources and to high energy astrophysics was borne in mind. (orig.)

  18. CRL X-RAY TUBE

    OpenAIRE

    Kolchevsky, N. N.; Petrov, P. V.

    2015-01-01

    A novel types of X-ray tubes with refractive lenses are proposed. CRL-R X-ray tube consists of Compound Refractive Lens- CRL and Reflection X-ray tube. CRL acts as X-ray window. CRL-T X-ray consists of CRL and Transmission X-ray tube. CRL acts as target for electron beam. CRL refractive lens acts as filter, collimator, waveguide and focusing lens. Properties and construction of the CRL X-ray tube are discussed.

  19. Spectral Softening in X-ray Afterglow of GRB 130925A as Predicted by Dust Scattering Model

    CERN Document Server

    Zhao, Yi-Nan

    2014-01-01

    Gamma-ray bursts (GRBs) usually occurs in a dense star-forming region with massive circum-burst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences, and sometimes can dominate the X-ray afterglow. In most of the previous studies, only Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius $a\\leq 0.1\\,{\\rm \\mu m}$) in the diffuse interstellar medium. When the size of the grains may significantly increase as in a more dense region where GRBs would occur, the RG approximation may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculat...

  20. Chest X-Ray

    Medline Plus

    Full Text Available ... this Site RadiologyInfo.org is produced by: Image/Video Gallery Your radiologist explains chest x-ray. Transcript ... time! Spotlight Recently posted: Pediatric MRI Intravascular Ultrasound Video: Chest CT Video:Thyroid Ultrasound Video: Head CT ...

  1. Chest X-Ray

    Medline Plus

    Full Text Available ... Pediatric Ultrasound Video: Angioplasty & vascular stenting Video: Arthrography Radiology and You About this Site RadiologyInfo.org is ... radiologist explains chest x-ray. Transcript Welcome to Radiology Info dot org! Hello, I’m Dr. Geoffrey ...

  2. Chest X-Ray

    Medline Plus

    Full Text Available ... this Site RadiologyInfo.org is produced by: Image/Video Gallery Your radiologist explains chest x-ray. Transcript ... Recently posted: Focused Ultrasound for Uterine Fibroids Dementia Video: General Ultrasound Video: Pediatric Nuclear Medicine Radiology and ...

  3. Medical x-ray

    International Nuclear Information System (INIS)

    This book describes the fundamental subject about medical radiography. It is a multidisciplinary field that requires cross professional input from scientists, engineers and medical doctors. However, it is presented in simple language to suit different levels of readers from x-ray operators and radiographers to physists, general practitioners and radiology specialists.The book is written in accordance to the requirements of the standard syllabus approved by the Ministry of Health Malaysia for the training of medical x-ray operator and general practitioners. In general, the content is not only designed to provide relevant and essential subject for related professionals in medical radiological services such as x-ray operator, radiographer and radiologists, but also to address those in associated radiological services including nurses, medical technologists and physicists.The book is organized and arranged sequentially into 3 parts for easy reference: Radiation safety; X-ray equipment and associated facilities; Radiography practices. With proper grasping of all these parts, the radiological services could be provided with confident and the highest professional standard. Thus, medical imaging with highest quality that can provide useful diagnostic information at minimum doses and at cost effective could be assured

  4. Synchrotron x-ray sources and new opportunities in the soil and environmental sciences

    International Nuclear Information System (INIS)

    This report contains the following papers: characteristics of the advanced photon source and comparison with existing synchrotron facilities; x-ray absorption spectroscopy: EXAFS and XANES -- A versatile tool to study the atomic and electronic structure of materials; applications of x-ray spectroscopy and anomalous scattering experiments in the soil and environmental sciences; X-ray fluorescence microprobe and microtomography

  5. Synchrotron x-ray sources and new opportunities in the soil and environmental sciences

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, D. (Purdue Univ., Lafayette, IN (USA)); Anderson, S. (Michigan State Univ., East Lansing, MI (USA)); Mattigod, S. (Pacific Northwest Lab., Richland, WA (USA))

    1990-07-01

    This report contains the following papers: characteristics of the advanced photon source and comparison with existing synchrotron facilities; x-ray absorption spectroscopy: EXAFS and XANES -- A versatile tool to study the atomic and electronic structure of materials; applications of x-ray spectroscopy and anomalous scattering experiments in the soil and environmental sciences; X-ray fluorescence microprobe and microtomography.

  6. Pyroelectric x-ray detectors and x-ray pyrometers

    International Nuclear Information System (INIS)

    This paper discusses pyroelectric detectors which are very promising x-ray detectors for intense pulsed x-ray/γ-ray measurements and can be used as x-ray pyrometers. They are fast, passive, and inherently flat in spectral response for low energy x-rays. The authors report tests of LiTaO3, Sr.5Ba.5Nb2O6 and LiNbO3 detectors at Nova laser with 1 ns low energy x-rays and at Zapp Z-pinch machine with 100 ns x-rays. The temporal and spectral responses are discussed

  7. Pyroelectric x-ray detectors and x-ray pyrometers

    International Nuclear Information System (INIS)

    Pyroelectric detectors are very promising x-ray detectors for intense pulsed x-ray/γ-ray measurements and can be used as x-ray pyrometers. They are fast, passive, and inherently flat in spectral response for low-energy x rays. We report our tests of LiTaO3 detectors at Nova laser with 1-ns low-energy x rays and at Zapp Z-pinch machine with 100-ns x rays. The temporal and spectral responses are discussed

  8. Small angle electron diffraction and deflection

    Directory of Open Access Journals (Sweden)

    T. Koyama

    2012-03-01

    Full Text Available Electron optical system is constructed in order to obtain small angle diffraction and Lorentz deflection of electrons at the order of down to 10-6 radian in the reciprocal space. Long-distance camera length up to 3000 m is achieved in a conventional transmission electron microscope with LaB6 thermal emission type. The diffraction pattern at 5 × 10-6 radian is presented in a carbon replica grating with 500 nm lattice spacing while the magnetic deflection pattern at 2 × 10-5 radian is exhibited in Permalloy elements. A simultaneous recording of electron diffraction and Lorentz deflection is also demonstrated in 180 degree striped magnetic domains of La0.825Sr0.175MnO3.

  9. X-ray diffraction

    International Nuclear Information System (INIS)

    We have been interested in structural elucidation by x-ray diffraction of compounds of biological interest. Understanding exactly how atoms are arranged in three-dimensional arrays as molecules can help explain the relationship between structure and functions. The species investigated may vary in size and shape; our recent studies included such diverse substances as antischistosomal drugs, a complex of cadmium with nucleic acid base, nitrate salts of adenine, and proteins

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... wrist, arm, elbow, shoulder, spine, pelvis, hip, thigh, knee, leg (shin), ankle or foot. top of page ... the patient standing upright, as in cases of knee x-rays. A portable x-ray machine is ...

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... images for evaluation. National and international radiology protection organizations continually review and update the technique standards used by radiology professionals. Modern x-ray systems have very controlled x-ray beams and dose ...

  12. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... fracture. guide orthopedic surgery, such as spine repair/fusion, joint replacement and fracture reductions. look for injury, ... and Media Arthritis X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety Images related to X-ray ( ...

  13. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and ...

  14. Dental X-ray apparatus

    International Nuclear Information System (INIS)

    Intra-oral dental X-ray apparatus for panoramic radiography is described in detail. It comprises a tubular target carrier supporting at its distal end a target with an inclined forward face. Image definition is improved by positioning in the path of the X-rays a window of X-ray transmitting ceramic material, e.g. 90% oxide of Be, or Al, 7% Si02. The target carrier forms a probe which can be positioned in the patient's mouth. X-rays are directed forwardly and laterally of the target to an X-ray film positioned externally. The probe is provided with a detachable sleeve having V-form arms of X-ray opaque material which serve to depress the tongue out of the radiation path and also shield the roof of the mouth and other regions of the head from the X-ray pattern. A cylindrical lead shield defines the X-ray beam angle. (author)

  15. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  16. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air appears black. Until recently, x-ray images were maintained on large film sheets (much ...

  17. Panoramic Dental X-Ray

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Panoramic Dental X-ray Panoramic dental x-ray uses a ... a large photographic negative). Today, most images are digital files that are stored electronically. These stored images ...

  18. Small angle neutron scattering study of pore microstructure in ceria compacts

    Indian Academy of Sciences (India)

    A K Patra; P U Sastry; Srirupa T Mukherjee; Vinila Bedekar; A K Tyagi

    2008-11-01

    Ceria powders were prepared by gel combustion process using cerium nitrate and hitherto unexplored amino acids such as aspartic acid, arginine and valine as fuels. The powders have been characterized by X-ray and laser diffraction. Cold pressed compacts of these powders have been sintered at 1250°C for 2 h. Internal pore microstructure of the sintered compacts has been investigated by small angle neutron scattering (SANS) over a scattering wave vector range of 0.003–0.17 nm-1. The SANS profiles indicate surface fractal morphology of the pore space with fractal dimensionality lying between 2.70 and 2.76.

  19. System of primary collimators of SR beam at the small-angle station for KSRS

    CERN Document Server

    Ariskin, N I; Korneev, V N; Sergienko, P M; Shishkov, V I; Sheromov, M A; Stankevich, V G; Vazina, A A

    2001-01-01

    The wide program of development of methods and experimental techniques for usage at the Kurchatov Synchrotron Radiation Source (KSRS) is implemented by us. The report illustrates a part of this program directed at creating the small-angle station DICSI-6 on the beam line 'Siberia-2'. It is intended for X-ray diffraction research of structures and structural changes of a wide range of objects in various areas of science and technology--molecular and cell biology, organic chemistry, solid-state physics, etc. Some technical information about the elaborated system of devices for station DICSI-6 intended for forming an X-ray synchrotron beam and method for adjustment of the system are considered.

  20. X-ray Crystallography Facility

    Science.gov (United States)

    2000-01-01

    Edward Snell, a National Research Council research fellow at NASA's Marshall Space Flight Center (MSFC), prepares a protein crystal for analysis by x-ray crystallography as part of NASA's structural biology program. The small, individual crystals are bombarded with x-rays to produce diffraction patterns, a map of the intensity of the x-rays as they reflect through the crystal.

  1. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... x-rays. top of page What does the equipment look like? The equipment typically used for bone x-rays consists of ... and joint abnormalities, such as arthritis. X-ray equipment is relatively inexpensive and widely available in emergency ...

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... The x-ray tube is connected to a flexible arm that is extended over the patient while an x-ray film holder or image recording plate is placed beneath the patient. top of page How does the procedure work? X-rays are a form of radiation like ...

  3. Tunable X-ray source

    Science.gov (United States)

    Boyce, James R.

    2011-02-08

    A method for the production of X-ray bunches tunable in both time and energy level by generating multiple photon, X-ray, beams through the use of Thomson scattering. The method of the present invention simultaneously produces two X-ray pulses that are tunable in energy and/or time.

  4. X-ray selected BALQSOs

    CERN Document Server

    Page, M J; Ceballos, M; Corral, A; Ebrero, J; Esquej, P; Krumpe, M; Mateos, S; Rosen, S; Schwope, A; Streblyanska, A; Symeonidis, M; Tedds, J A; Watson, M G

    2016-01-01

    We study a sample of six X-ray selected broad absorption line (BAL) quasi-stellar objects (QSOs) from the XMM-Newton Wide Angle Survey. All six objects are classified as BALQSOs using the classic balnicity index, and together they form the largest sample of X-ray selected BALQSOs. We find evidence for absorption in the X-ray spectra of all six objects. An ionized absorption model applied to an X-ray spectral shape that would be typical for non-BAL QSOs (a power law with energy index alpha=0.98) provides acceptable fits to the X-ray spectra of all six objects. The optical to X-ray spectral indices, alpha_OX, of the X-ray selected BALQSOs, have a mean value of 1.69 +- 0.05, which is similar to that found for X-ray selected and optically selected non-BAL QSOs of similar ultraviolet luminosity. In contrast, optically-selected BALQSOs typically have much larger alpha_OX and so are characterised as being X-ray weak. The results imply that X-ray selection yields intrinsically X-ray bright BALQSOs, but their X-ray sp...

  5. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... lies. A drawer under the table holds the x-ray film or image recording plate . Sometimes the x-ray ... that is extended over the patient while an x-ray film holder or image recording plate is placed beneath ...

  6. X-Ray Exam: Ankle

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Ankle KidsHealth > For Parents > X-Ray Exam: Ankle Print A A A Text Size ... español Radiografía: tobillo What It Is An ankle X-ray is a safe and painless test that uses ...

  7. X-Ray Exam: Finger

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Finger KidsHealth > For Parents > X-Ray Exam: Finger Print A A A Text Size ... español Radiografía: dedo What It Is A finger X-ray is a safe and painless test that uses ...

  8. X-Ray Exam: Wrist

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Wrist KidsHealth > For Parents > X-Ray Exam: Wrist Print A A A Text Size ... español Radiografía: muñeca What It Is A wrist X-ray is a safe and painless test that uses ...

  9. X-Ray Exam: Hip

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Hip KidsHealth > For Parents > X-Ray Exam: Hip Print A A A Text Size ... español Radiografía: cadera What It Is A hip X-ray is a safe and painless test that uses ...

  10. X-Ray Exam: Forearm

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Forearm KidsHealth > For Parents > X-Ray Exam: Forearm Print A A A Text Size ... español Radiografía: brazo What It Is A forearm X-ray is a safe and painless test that uses ...

  11. X-Ray Exam: Pelvis

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Pelvis KidsHealth > For Parents > X-Ray Exam: Pelvis Print A A A Text Size ... español Radiografía: pelvis What It Is A pelvis X-ray is a safe and painless test that uses ...

  12. X-Ray Exam: Foot

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Foot KidsHealth > For Parents > X-Ray Exam: Foot Print A A A Text Size ... español Radiografía: pie What It Is A foot X-ray is a safe and painless test that uses ...

  13. X-Ray Absorption and Scattering by Interstellar Grains

    CERN Document Server

    Hoffman, John A

    2015-01-01

    Interstellar abundance determinations from fits to X-ray absorption edges often rely on the following false assumptions: (1) the grains are "optically thin" at the observed X-ray wavelengths, and (2) scattering is insignificant and can be ignored. We show instead that scattering contributes significantly to the attenuation of X-rays for realistic dust grain size distributions and substantially modifies the spectrum near absorption edges of elements present in grains. The dust attenuation modules used in major X-ray spectral fitting programs do not take this into account. We show that the consequences of neglecting scattering on the determination of interstellar elemental abundances are modest; however, scattering (along with uncertainties in the grain size distribution) must be taken into account when near-edge extinction fine structure is used to infer dust mineralogy. We advertise the benefits and accuracy of anomalous diffraction theory for both X-ray halo analysis and near edge absorption studies. An open...

  14. Theoretical analysis on x-ray cylindrical grating interferometer

    CERN Document Server

    Cong, Wenxiang; Wang, Ge

    2015-01-01

    Grating interferometer is a state of art x-ray imaging approach, which can simultaneously acquire information of x-ray attenuation, phase shift, and small angle scattering. This approach is very sensitive to micro-structural variation and offers superior contrast resolution for biological soft tissues. The present grating interferometer often uses flat gratings, with serious limitations in the field of view and the flux of photons. The use of curved gratings allows perpendicular incidence of x-rays on the gratings, and gives higher visibility over a larger field of view than a conventional interferometer with flat gratings. In the study, we present a rigorous theoretical analysis of the self-imaging of curved transmission gratings based on Rayleigh-Sommerfeld diffraction. Numerical simulations have demonstrated the self-imaging phenomenon of cylindrical grating interferometer. The theoretical results are in agreement with the results of numerical simulations.

  15. X-ray today

    Energy Technology Data Exchange (ETDEWEB)

    Neitzel, U. [Philips Medical Systems, Hamburg (Germany)

    2001-09-01

    The interest attracted by the new imaging modalities tends to overshadow the continuing importance of projection radiography and fluoroscopy. Nevertheless, projection techniques still represent by far the greatest proportion of diagnostic imaging examinations, and play an essential role in the growing number of advanced interventional procedures. This article describes some of the latest developments in X-ray imaging technology, using two products from the Philips range as examples: the Integris Allura cardiovascular system with 3D image reconstruction, and the BV Pulsera: a high-end, multi-functional mobile C-arm system with cardiac capabilities. (orig.)

  16. Spatial Harmonic Imaging of X-ray Scattering—Initial Results

    OpenAIRE

    Wen, Han; Bennett, Eric E.; Hegedus, Monica M.; Carroll, Stefanie C.

    2008-01-01

    Coherent X-ray scattering is related to the electron density distribution by a Fourier transform, and therefore a window into the microscopic structures of biological samples. Current techniques of scattering rely on small-angle measurements from highly collimated X-ray beams produced from synchrotron light sources. Imaging of the distribution of scattering provides a new contrast mechanism which is different from absorption radiography, but is a lengthy process of raster or flue scans of the...

  17. Inner Stucture of Thin Films of Lamellar Poly(styrene-b-butadiene) Diblock Copolymers as revealed by Grazing-Incidence Small-Angle Scattering

    DEFF Research Database (Denmark)

    Busch, Peter; Posselt, Dorthe; Smilgies, Detlef-Matthias;

    2007-01-01

    The lamellar orientation in supported, thin films of poly(styrene-b-butadiene) (P(S-b-B)) depends on block copolymer molar mass. We have studied films from nine block copolymer samples with molar masses between 13.9 and 183 kg/mol using grazing-incidence small-angle X-ray scattering (GISAXS) and ...

  18. Investigation of digestion Kinetics in commercial starches using in-situ small-angle neutron scattering

    International Nuclear Information System (INIS)

    Full text: The digestion of starch has been the subject of many investigations, mostly involving in vitro measurement of the susceptibility of starches to attack by different enzymes, rather than measuring actual digestibility in vivo. The rate and extent of amylolytic hydrolysis of granular starches is known to vary according to botanical origin. Granule characteristics considered to influence susceptibility to attack by alpha-amylase include crystallinity, granule size and available specific surface, amylose content, porosity, structural inhomogeneities and degree of integrity. Most in-vitro studies of granular starch digestion have been limited to samples for which aliquots have been removed from the reaction mixture at various time intervals and freeze-dried to be subsequently characterized using a range of techniques. It remains unclear whether sample preparation creates artefacts in the samples. In this study, we have studied the kinetics of starch digestion of several commercial granular starches by time-resolved small-angle neutron scattering using an in-situ digestion chamber allowing, for the first time, to follow structural changes of starch in the course of digestion directly in the digestion mixture. Additionally, samples before and after digestion were studied by x-ray diffraction, small-angle x-ray scattering, differential scanning calorimetry and microscopy. Microscopy revealed that studied starches, which varied in their amylose content and digestion kinetics, followed different modes of attack The multidisciplinary approach allowed the nanostructural changes detected by small-angle scattering in the course of enzymic breakdown to be correlated with changes in crystallinity and functional properties.

  19. Topological X-Rays Revisited

    Science.gov (United States)

    Lynch, Mark

    2012-01-01

    We continue our study of topological X-rays begun in Lynch ["Topological X-rays and MRI's," iJMEST 33(3) (2002), pp. 389-392]. We modify our definition of a topological magnetic resonance imaging and give an affirmative answer to the question posed there: Can we identify a closed set in a box by defining X-rays to probe the interior and without…

  20. X-ray instrumentation for SR beamlines

    CERN Document Server

    Kovalchuk, M V; Zheludeva, S I; Aleshko-Ozhevsky, O P; Arutynyan, E H; Kheiker, D M; Kreines, A Y; Lider, V V; Pashaev, E M; Shilina, N Y; Shishkov, V A

    2000-01-01

    The main possibilities and parameters of experimental X-ray stations are presented: 'Protein crystallography', 'X-ray structure analysis', 'High-precision X-ray optics', 'X-ray crystallography and material science', 'X-ray topography', 'Photoelectron X-ray standing wave' that are being installed at Kurchatov SR source by A.V. Shubnikov Institute of Crystallography.

  1. X-ray lithography sources

    International Nuclear Information System (INIS)

    Synchrotron from dipole magnets in electron storage rings has emerged as a useful source of x-rays for lithography. To meet the need for these sources numerous groups around the world have embarked on projects to design and construct storage rings for x-ray lithography. Both conventional electromagnets as well as superconducting (SC) dipoles have been incorporated into the various designs. An overview of the worldwide effort to produce commercial x-ray sources will be presented. To better illustrate the elements involved in these sources a closer examination of the Superconducting X-ray Lithography Source Project (SXLS) at BNL will be presented. 11 refs., 1 fig., 5 tabs

  2. Soft X-ray optics

    CERN Document Server

    Spiller, Eberhard A

    1993-01-01

    This text describes optics mainly in the 10 to 500 angstrom wavelength region. These wavelengths are 50 to 100 times shorter than those for visible light and 50 to 100 times longer than the wavelengths of medical x rays or x-ray diffraction from natural crystals. There have been substantial advances during the last 20 years, which one can see as an extension of optical technology to shorter wavelengths or as an extension of x-ray diffraction to longer wavelengths. Artificial diffracting structures like zone plates and multilayer mirrors are replacing the natural crystals of x-ray diffraction.

  3. X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  4. X-ray Fluorescence Sectioning

    CERN Document Server

    Cong, Wenxiang

    2012-01-01

    In this paper, we propose an x-ray fluorescence imaging system for elemental analysis. The key idea is what we call "x-ray fluorescence sectioning". Specifically, a slit collimator in front of an x-ray tube is used to shape x-rays into a fan-beam to illuminate a planar section of an object. Then, relevant elements such as gold nanoparticles on the fan-beam plane are excited to generate x-ray fluorescence signals. One or more 2D spectral detectors are placed to face the fan-beam plane and directly measure x-ray fluorescence data. Detector elements are so collimated that each element only sees a unique area element on the fan-beam plane and records the x-ray fluorescence signal accordingly. The measured 2D x-ray fluorescence data can be refined in reference to the attenuation characteristics of the object and the divergence of the beam for accurate elemental mapping. This x-ray fluorescence sectioning system promises fast fluorescence tomographic imaging without a complex inverse procedure. The design can be ad...

  5. Application of SOI Area Detectors to Synchrotron Radiation X-ray Experiments

    CERN Document Server

    Hashimoto, Ryo; Kumai, Reiji; Kishimoto, Shunji

    2015-01-01

    Application of new detectors using Silicon-On-Insulator (SOI) technology has been started in the Photon Factory, KEK. This project has two purposes. The first purpose is to develop a pulse-counting-type X-ray detector which can be used in synchrotron soft X-ray experiments. The second one is to apply the SOI area detector developed by RIKEN, SOPHIAS, to X-ray diffraction and small-angle scattering experiments in Photon Factory. In this paper, we introduce the current status of our project.

  6. EDITORIAL Proceedings of the XIV International Conference on Small-Angle Scattering, SAS-2009

    Science.gov (United States)

    Ungar, Goran; Heenan, Richard

    2010-10-01

    There are 52 papers in these Proceedings. The papers are divided into 10 thematic sections and a section for invited papers and reviews. The sections and the respective section editors are given below. Section Editor(s) Invited Papers and Reviews Peter Griffiths, Wim Bras, Rudolf Winter Beamlines and Instrumentation Elliot Gilbert, Wim Bras, Nigel Rhodes Theory, Data processing and Modelling Jan Skov Pedersen, Carlo Knupp Biological Systems and Membranes Richard Heenan, Cameron Neylon Ceramics, Glasses and Porous Materials Rudolf Winter Colloids and Solutions Peter Griffiths Hierarchical Structures and Fibres Steve Eichhorn, Karen Edler Metallic and Magnetic Systems Armin Hoell Polymers Patrick Fairclough Time resolved Diffraction, Kinetic and Dynamical Studies João Cabral, Christoph Rau We are grateful to all section editors and the many anonymous referees for their invaluable effort which made the publication of the Proceedings possible. The refereeing process was strict and thorough, some papers were rejected and most were improved. The resulting compendium gives a good overview of recent developments in small-angle X-ray and neutron scattering theory, application, methods of analysis and instrumentation. Thus it should be a useful source of reference for a number of years to come. The papers are a good reflection of the material presented at the meeting. Because of the general high quality of the articles, it was difficult to decide which to highlight and be fair to all contributors. The following in particular have caught the attention of the editors. Highlighted papers A statistical survey of publications reporting the application of SAXS and SANS by Aldo Craievich (paper 012003) is recommended reading for anyone needing convincing about the vibrancy of this scientific field and the ever expanding use of these techniques. Two aspects of coherent X-ray scattering, made available by the advent of the 3rd generation synchrotron sources, are discussed in the

  7. Radioisotope x-ray analysis

    International Nuclear Information System (INIS)

    Radioisotope x-ray fluorescence and x-ray preferential absorption (XRA) techniques are used extensively for the analysis of materials, covering such diverse applications as analysis of alloys, coal, environmental samples, paper, waste materials, and metalliferous mineral ores and products. Many of these analyses are undertaken in the harsh environment of industrial plants and in the field. Some are continuous on-line analyses of material being processed in industry, where instantaneous analysis information is required for the control of rapidly changing processes. Radioisotope x-ray analysis systems are often tailored to a specific but limited range of applications. They are simpler and often considerably less expensive than analysis systems based on x-ray tubes. These systems are preferred to x-ray tube techniques when simplicity, ruggedness, reliability, and cost of equipment are important; when minimum size, weight, and power consumption are necessary; when a very constant and predictable x-ray output is required; when the use of high-energy x-rays is advantageous; and when short x-ray path lengths are required to minimize the absorption of low-energy x-rays in air. This chapter reviews radioisotope XRF, preferential absorption, and scattering techniques. Some of the basic analysis equations are given. The characteristics of radioisotope sources and x-ray detectors are described, and then the x-ray analytical techniques are presented. The choice of radioisotope technique for a specific application is discussed. This is followed by a summary of applications of these techniques, with a more detailed account given of some of the applications, particularly those of considerable industrial importance. 79 refs., 28 figs., 7 tabs

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... clothing that might interfere with the x-ray images. Women should always inform their physician and x-ray ... small burst of radiation that passes through the body, recording an image on photographic film or a special detector. Different ...

  9. X-ray diagnostic equipment

    International Nuclear Information System (INIS)

    An X-ray tube is connected to several different image processing devices in X-ray diagnostic equipment. Only a single organ selector is allocated to it, for which the picture parameters for each image processing device are selected. The choice of the correct combination of picture parameters is made by means of a selector switch. (DG)

  10. X-ray tube arrangement

    International Nuclear Information System (INIS)

    An x-ray tube is described incorporating an elongated target/ anode over which the electron beam is deflected and from which x-rays are emitted. Improved methods of monitoring and controlling the amplitude of the beam deflection are presented. (U.K.)

  11. 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

  12. Spherical grating based x-ray Talbot interferometry

    International Nuclear Information System (INIS)

    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

  13. 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...

  14. Serial femtosecond X-ray diffraction of enveloped virus microcrystals

    Directory of Open Access Journals (Sweden)

    Robert M. Lawrence

    2015-07-01

    Full Text Available Serial femtosecond crystallography (SFX using X-ray free-electron lasers has produced high-resolution, room temperature, time-resolved protein structures. We report preliminary SFX of Sindbis virus, an enveloped icosahedral RNA virus with ∼700 Å diameter. Microcrystals delivered in viscous agarose medium diffracted to ∼40 Å resolution. Small-angle diffuse X-ray scattering overlaid Bragg peaks and analysis suggests this results from molecular transforms of individual particles. Viral proteins undergo structural changes during entry and infection, which could, in principle, be studied with SFX. This is an important step toward determining room temperature structures from virus microcrystals that may enable time-resolved studies of enveloped viruses.

  15. X-ray diffraction apparatus

    International Nuclear Information System (INIS)

    The invention provides an x-ray diffraction apparatus permitting the rotation of the divergence sit in conjunction with the rotation of the x-ray irradiated specimen, whereby the dimensions of the x-ray irradiated portion of the specimen remain substantially constant during the rotation of the specimen. In a preferred embodiment, the divergence slit is connected to a structural element linked with a second structural element connected to the specimen such that the divergence slit rotates at a lower angular speed than the specimen

  16. Synthesis of 1 nm Pd Nanoparticles in a Microfluidic Reactor: Insights from in Situ X ray Absorption Fine Structure Spectroscopy and Small-Angle X ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Karim, Ayman M.; Al Hasan, Naila M.; Ivanov, Sergei A.; Siefert, Soenke; Kelly, Ryan T.; Hallfors, Nicholas G.; Benavidez, Angelica D.; Kovarik, Libor; Jenkins, Aaron; Winans, R. E.; Datye, Abhaya K.

    2015-06-11

    In this paper we show that the temporal separation of nucleation and growth is not a necessary condition for the colloidal synthesis of monodisperse nanoparticles. The synthesis mechanism of Pd nanoparticles was determined by in situ XAFS and SAXS in a microfluidic reactor capable of millisecond up to an hour time resolution. The SAXS results showed two autocatalytic growth phases, a fast growth phase followed by a very slow growth phase. The steady increase in the number of particles throughout the two growth phases indicates the synthesis is limited by slow continuous nucleation. The transition from fast to slow growth was caused by rapid increase in bonding with the capping agent as shown by XAFS. Based on this fundamental understanding of the synthesis mechanism, we show that 1 nm monodisperse Pd nanoparticles can be synthesized at low temperature using a strong binding capping agent such as trioctylphosphine (TOP).

  17. Analyser-based x-ray imaging for biomedical research

    International Nuclear Information System (INIS)

    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)

  18. Accurate Modeling of X-ray Extinction by Interstellar Grains

    Science.gov (United States)

    Hoffman, John; Draine, B. T.

    2016-02-01

    Interstellar abundance determinations from fits to X-ray absorption edges often rely on the incorrect assumption that scattering is insignificant and can be ignored. We show instead that scattering contributes significantly to the attenuation of X-rays for realistic dust grain size distributions and substantially modifies the spectrum near absorption edges of elements present in grains. The dust attenuation modules used in major X-ray spectral fitting programs do not take this into account. We show that the consequences of neglecting scattering on the determination of interstellar elemental abundances are modest; however, scattering (along with uncertainties in the grain size distribution) must be taken into account when near-edge extinction fine structure is used to infer dust mineralogy. We advertise the benefits and accuracy of anomalous diffraction theory for both X-ray halo analysis and near edge absorption studies. We present an open source Fortran suite, General Geometry Anomalous Diffraction Theory (GGADT), that calculates X-ray absorption, scattering, and differential scattering cross sections for grains of arbitrary geometry and composition.

  19. Duodenal X-ray diagnostics

    International Nuclear Information System (INIS)

    The publication provides an overview of duodenal X-ray diagnostics with the aid of barium meals in 1362 patients. The introducing paragraphs deal with the topographic anatomy of the region and the methodics of X-ray investigation. The chapter entitled ''processes at the duodenum itself'' describes mainly ulcers, diverticula, congenital anomalies, tumors and inflammations. The neighbourhood processes comprise in the first place diseases having their origin at the pancreas and bile ducts. As a conclusion, endoscopic rectograde cholangio-pancreaticography and percutaneous transhepatic cholangiography are pointed out as advanced X-ray investigation methods. In the annex of X-ray images some of the described phenomena are shown in exemplary manner. (orig./MG)

  20. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... like a photographic negative). Today, most images are digital files that are stored electronically. These stored images ... and places the x-ray film holder or digital recording plate under the table in the area ...

  1. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to ... See the Safety page for more information about pregnancy and x-rays. top of page What does ...

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the baby. See the Safety page for more information about pregnancy and x-rays. top of page ... procedure varies. See the Safety page for more information about radiation dose. Women should always inform their ...

  3. X-ray microtomographic scanners

    Energy Technology Data Exchange (ETDEWEB)

    Syryamkin, V. I., E-mail: klestov-simon@mail.ru; Klestov, S. A., E-mail: klestov-simon@mail.ru [National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2015-11-17

    The article studies the operating procedures of an X-ray microtomographic scanner and the module of reconstruction and analysis 3D-image of a test sample in particular. An algorithm for 3D-image reconstruction based on image shadow projections and mathematical methods of the processing are described. Chapter 1 describes the basic principles of X-ray tomography and general procedures of the device developed. Chapters 2 and 3 are devoted to the problem of resources saving by the system during the X-ray tomography procedure, which is achieved by preprocessing of the initial shadow projections. Preprocessing includes background noise removing from the images, which reduces the amount of shadow projections in general and increases the efficiency of the group shadow projections compression. In conclusion, the main applications of X-ray tomography are presented.

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and ... in the typical diagnostic range for this exam. Risks There is always a slight chance of cancer ...

  5. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... can be taken to the patient in a hospital bed or the emergency room. The x-ray ... and international radiology protection organizations continually review and update the technique standards used by radiology professionals. Modern ...

  6. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the patient in a hospital bed or the emergency room. The x-ray tube is connected to ... equipment is relatively inexpensive and widely available in emergency rooms, physician offices, ambulatory care centers, nursing homes ...

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... or in bones. top of page How should I prepare? Most bone x-rays require no special ... to 10 minutes. top of page What will I experience during and after the procedure? A bone ...

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the body absorb the x-rays in varying degrees. Dense bone absorbs much of the radiation while ... is further reviewed by committees from the American College of Radiology (ACR) and the Radiological Society of ...

  9. Dental X-ray apparatus

    International Nuclear Information System (INIS)

    Intra-oral dental X-ray apparatus for panoramic dental radiography is described in detail. It comprises an electron gun having an elongated tubular target carrier extending into the patient's mouth. The carrier supports an inclined target for direction of an X-ray pattern towards a film positioned externally of the patient's mouth. Image definition is improved by a focusing anode which focuses the electron beam into a sharp spot (0.05 to 0.10 mm diameter) on the target. The potential on the focusing anode is adjustable to vary the size of the spot. An X-ray transmitting ceramic (oxides of Be, Al and Si) window is positioned adjacent to the front face of the target. The electron beam can be magnetically deflected to change the X-ray beam direction. (author)

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... during x-ray examinations to use the lowest radiation dose possible while producing the best images for evaluation. National and international radiology protection organizations continually review and update the technique standards ...

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... technologist, an individual specially trained to perform radiology examinations, positions the patient on the x-ray table ... bone is forming), for comparison purposes. When the examination is complete, you may be asked to wait ...

  12. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... replacement and fracture reductions. look for injury, infection, arthritis , abnormal bone growths and bony changes seen in ... injuries, including fractures, and joint abnormalities, such as arthritis. X-ray equipment is relatively inexpensive and widely ...

  13. X-Ray Assembler Data

    Data.gov (United States)

    U.S. Department of Health & Human Services — Federal regulations require that an assembler who installs one or more certified components of a diagnostic x-ray system submit a report of assembly. This database...

  14. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... a large photographic negative). Today, most images are digital files that are stored electronically. These stored images ... and places the x-ray film holder or digital recording plate under the table in the area ...

  15. Accelerator x-ray sources

    CERN Document Server

    Talman, Richard

    2007-01-01

    This first book to cover in-depth the generation of x-rays in particle accelerators focuses on electron beams produced by means of the novel Energy Recovery Linac (ERL) technology. The resulting highly brilliant x-rays are at the centre of this monograph, which continues where other books on the market stop. Written primarily for general, high energy and radiation physicists, the systematic treatment adopted by the work makes it equally suitable as an advanced textbook for young researchers.

  16. X-ray fluorescence holography

    CERN Document Server

    Hayashi, K; Takahashi, Y

    2003-01-01

    X-ray fluorescence holography (XFH) is a new structural analysis method of determining a 3D atomic arrangement around fluorescing atoms. We developed an XFH apparatus using advanced X-ray techniques and succeeded in obtaining high-quality hologram data. Furthermore, we introduced applications to the structural analysis of a thin film and the environment around dopants and, discussed the quantitative analysis of local lattice distortion. (author)

  17. Electromechanical x-ray generator

    Energy Technology Data Exchange (ETDEWEB)

    Watson, Scott A; Platts, David; Sorensen, Eric B

    2016-05-03

    An electro-mechanical x-ray generator configured to obtain high-energy operation with favorable energy-weight scaling. The electro-mechanical x-ray generator may include a pair of capacitor plates. The capacitor plates may be charged to a predefined voltage and may be separated to generate higher voltages on the order of hundreds of kV in the AK gap. The high voltage may be generated in a vacuum tube.

  18. Operando X-ray Investigation of Electrode/Electrolyte Interfaces in Model Solid Oxide Fuel Cells

    OpenAIRE

    Volkov, Sergey; Vonk, Vedran; Khorshidi, Navid; Franz, Dirk; Kubicek, Markus; Kilic, Volkan; Felici, Roberto; Huber, Tobias M.; Navickas, Edvinas; Rupp, Ghislain M.; Fleig, Jürgen; Stierle, Andreas

    2016-01-01

    We employed operando anomalous surface X-ray diffraction to investigate the buried interface between the cathode and the electrolyte of a model solid oxide fuel cell with atomic resolution. The cell was studied under different oxygen pressures at elevated temperatures and polarizations by external potential control. Making use of anomalous X-ray diffraction effects at the Y and Zr K-edges allowed us to resolve the interfacial structure and chemical composition of a (100)-oriented, 9.5 mol % y...

  19. X-ray diagnostic apparatus

    International Nuclear Information System (INIS)

    A falling load type X-ray diagnostic apparatus comprises a low voltage power source, AC-DC converting means connected to the low voltage power source so as to apply a rectified low DC voltage, chopping means connected to the AC-DC converting means and chopping said DC voltage into a low AC voltage, high voltage applying means for transforming said low AC voltage into a high AC voltage, said high AC voltage being applied as a tube voltage to an X-ray tube from which X-rays are irradiated toward an object to be examined, means for controlling a filament heating power of the X-ray tube, programming means for supplying a control signal to said filament heating control means so as to reduce the emission current of said X-ray tube during the irradiation, and chopper control means for controlling the chopping ratio of said chopping means by evaluating said rectified DC voltage with a preset tube voltage generated in said programming means, said programming means compensating said tube voltage by receiving said control signal in such a manner that said tube voltage is maintained substantially constant during the irradiation by varying said preset tube voltage so as to control the chopping ratio based upon the reduction of the filament heating power for the X-ray tube

  20. Low energy (soft) x rays

    International Nuclear Information System (INIS)

    Dosimetry of low-energy (soft) X rays produced by the SOFTEX Model CMBW-2 was performed using Nuclear Associates Type 30 - 330 PTW, Exradin Type A2, and Shonka-Wyckoff ionization chambers with a Keithley Model 602 electrometer. Thermoluminescent (BeO chip) dosimeters were used with a Harshaw Detector 2000-A and Picoammeter-B readout system. Beam quality measurements were made using aluminum absorbers; exposure rates were assessed by the current of the X-ray tube and by exposure times. Dose distributions were established, and the average factors for non-uniformity were calculated. The means of obtaining accurate absorbed and exposed doses using these methods are discussed. Survival of V79 cells was assessed by irradiating them with soft X rays, 200 kVp X rays, and 60Co gamma rays. The relative biological effectiveness (RBE) values for soft X rays with 0, 0.2, 0.7 mm added thicknesses of aluminum were 1.6, which were compared to 60Co. The RBE of 200 kVp X rays relative to 60Co was 1.3. Results of this study are available for reference in future RERF studies of cell survival. (author)

  1. Comparative study of GeO2/Ge and SiO2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy

    Science.gov (United States)

    Mori, Daichi; Oka, Hiroshi; Hosoi, Takuji; Kawai, Kentaro; Morita, Mizuho; Crumlin, Ethan J.; Liu, Zhi; Watanabe, Heiji; Arima, Kenta

    2016-09-01

    The energy difference between the oxide and bulk peaks in X-ray photoelectron spectroscopy (XPS) spectra was investigated for both GeO2/Ge and SiO2/Si structures with thickness-controlled water films. This was achieved by obtaining XPS spectra at various values of relative humidity (RH) of up to ˜15%. The increase in the energy shift is more significant for thermal GeO2 on Ge than for thermal SiO2 on Si above ˜10-4% RH, which is due to the larger amount of water molecules that infiltrate into the GeO2 film to form hydroxyls. Analyzing the origins of this energy shift, we propose that the positive charging of a partially hydroxylated GeO2 film, which is unrelated to X-ray irradiation, causes the larger energy shift for GeO2/Ge than for SiO2/Si. A possible microscopic mechanism of this intrinsic positive charging is the emission of electrons from adsorbed water species in the suboxide layer of the GeO2 film to the Ge bulk, leaving immobile cations or positively charged states in the oxide. This may be related to the reported negative shift of flat band voltages in metal-oxide-semiconductor diodes with an air-exposed GeO2 layer.

  2. Leather structure determination by small-angle X-ray scattering (SAXS): cross sections of ovine and bovine leather.

    Science.gov (United States)

    Basil-Jones, Melissa M; Edmonds, Richard L; Allsop, Timothy F; Cooper, Sue M; Holmes, Geoff; Norris, Gillian E; Cookson, David J; Kirby, Nigel; Haverkamp, Richard G

    2010-05-12

    SAXS has been applied to structural determination in leather. The SAXS beamline at the Australian Synchrotron provides 6 orders of magnitude dynamic range, enabling a rich source of structural information from scattering patterns of leather sections. SAXS patterns were recorded for q from 0.004 to 0.223 A(-1). Collagen d spacing varied across ovine leather sections from 63.8 nm in parts of the corium up to 64.6 nm in parts of the grain. The intensity of the collagen peak at q = 0.06 A(-1) varied by 1 order of magnitude across ovine leather sections with the high-intensity region in the corium and the low intensity in the grain. The degree of fiber orientation and the dispersion of the orientation has been quantified in leather. It is shown how the technique provides a wealth of useful information that may be used to characterize and compare leathers, skin, and connective tissue.

  3. Collagen fibril orientation in ovine and bovine leather affects strength: a small angle X-ray scattering (SAXS) study.

    Science.gov (United States)

    Basil-Jones, Melissa M; Edmonds, Richard L; Cooper, Sue M; Haverkamp, Richard G

    2011-09-28

    There is a large difference in strength between ovine and bovine leather. The structure and arrangement of fibrous collagen in leather and the relationship between collagen structure and leather strength has until now been poorly understood. Synchrotron based SAXS is used to characterize the fibrous collagen structure in a series of ovine and bovine leathers and to relate it to tear strength. SAXS gives quantitative information on the amount of fibrous collagen, the orientation (direction and spread) of the collagen microfibrils, and the d-spacing of the collagen. The amount of collagen varies through the thickness of the leather from the grain to the corium, with a greater concentration of crystalline collagen measured toward the corium side. The orientation index (OI) is correlated strongly with strength in ovine leather and between ovine and bovine leathers. Stronger leather has the fibrils arranged mostly parallel to the plane of the leather surface (high OI), while weaker leather has more out-of-plane fibrils (low OI). With the measurement taken parallel to the animal's backbone, weak (19.9 N/mm) ovine leather has an OI of 0.422 (0.033), stronger (39.5 N/mm) ovine leather has an OI of 0.452 (0.033), and bovine leather with a strength of (61.5 N/mm) has an OI of 0.493 (0.016). The d-spacing profile through leather thickness also varies according to leather strength, with little variation being detected in weak ovine leather (average=64.3 (0.5) nm), but with strong ovine leather and bovine leather (which is even stronger) exhibiting a dip in d-spacing (from 64.5 nm at the edges dropping to 62 nm in the center). This work provides a clear understanding of a nanostructural characteristic of ovine and bovine leather that leads to differences in strength.

  4. Structural analysis of flexible proteins in solution by SmallAngle X-ray Scattering combined with crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Tsutakawa, Susan E.; Hura, Greg L.; Frankel, Ken A.; Cooper,Priscilla K.; Tainer, John A.

    2006-05-25

    In the last few years, SAXS of biological materials has been rapidly evolving and promises to move structural analysis to a new level. Recent innovations in SAXS data analysis allow ab initio shape predictions of proteins in solution. Furthermore, experimental scattering data can be compared to calculated scattering curves from the growing data base of solved structures and also identify aggregation and unfolded proteins. Combining SAXS results with atomic resolution structures enables detailed characterizations in solution of mass, radius, conformations, assembly, and shape changes associated with protein folding and functions. SAXS can efficiently reveal the spatial organization of protein domains, including domains missing from or disordered in known crystal structures, and establish cofactor or substrate-induced conformational changes. For flexible domains or unstructured regions that are not amenable for study by many other structural techniques, SAXS provides a unique technology. Here, we present SAXS shape predictions for PCNA that accurately predict a trimeric ring assembly and for a full-length DNA repair glycosylase with a large unstructured region. These new results in combination with illustrative published data show how SAXS combined with high resolution crystal structures efficiently establishes architectures, assemblies, conformations, and unstructured regions for proteins and protein complexes in solution.

  5. Extensive small-angle X-ray scattering studies of blood coagulation factor VIIa reveal interdomain flexibility

    DEFF Research Database (Denmark)

    Mosbæk, Charlotte Rode; Nolan, David; Persson, Egon;

    2010-01-01

    Blood coagulation factor VIIa (FVIIa) is used in the treatment of replacement therapy resistant hemophilia patients, and FVIIa is normally activated upon complex formation with tissue factor (TF), potentially in context with structural rearrangements. The solution behavior of uncomplexed FVIIa...

  6. Simulation of the shape of chaperonins using the small-angle x-ray scattering curves and torus form factor

    Energy Technology Data Exchange (ETDEWEB)

    Amarantov, S. V., E-mail: amarantov_s@mail.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Naletova, I. N. [Moscow State University, Belozerskii Institute of Molecular Biology and Bioorganic Chemistry (Russian Federation); Kurochkina, L. P. [Russian Academy of Sciences, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry (Russian Federation)

    2011-08-15

    The inverse scattering problem has been solved for protein complexes whose surfaces can be described by a set of the simplest doubly connected surfaces in the uniform approximation (a scattering potential inside the molecule is a constant). Solutions of two proteins-well-known GroEL bacterial chaperonin and poor-studied bacteriophage chaperonin, which is a product of 146 gene (gp146)-were taken for the experiment. The shapes of protein complexes have been efficiently reconstructed from the experimental scattering curves. The shell method, the method of the rotation of amino acid sequences with the use of the form factor of an amino acid, and the method of seeking the model parameters of a protein complex with the preliminarily obtained form factor of the model have been used to reconstruct the shape of these particles.

  7. Center for X-Ray Optics, 1992

    International Nuclear Information System (INIS)

    This report discusses the following topics: Center for X-Ray Optics; Soft X-Ray Imaging wit Zone Plate Lenses; Biological X-Ray microscopy; Extreme Ultraviolet Lithography for Nanoelectronic Pattern Transfer; Multilayer Reflective Optics; EUV/Soft X-ray Reflectometer; Photoemission Microscopy with Reflective Optics; Spectroscopy with Soft X-Rays; Hard X-Ray Microprobe; Coronary Angiography; and Atomic Scattering Factors

  8. Observation of X-ray shadings in synchrotron radiation-total reflection X-ray fluorescence using a color X-ray camera

    International Nuclear Information System (INIS)

    Absorption effects and the impact of specimen shape on TXRF analysis has been discussed intensively. Model calculations indicated that ring shaped specimens should give better results in terms of higher counts per mass signals than filled rectangle or circle shaped specimens. One major reason for the difference in signal is shading effects. Full field micro-XRF with a color X-ray camera (CXC) was used to investigate shading, which occurs when working with small angles of excitation as in TXRF. The device allows monitoring the illuminated parts of the sample and the shaded parts at the same time. It is expected that sample material hit first by the primary beam shade material behind it. Using the CXC shading could be directly visualized for the high concentration specimens. In order to compare the experimental results with calculation of the shading effect the generation of controlled specimens is crucial. This was achieved by “drop on demand” technology. It allows generating uniform, microscopic deposits of elements. The experimentally measured shadings match well with those expected from calculation. - Highlights: • Use of a color X-ray camera and drop on demand printing to diagnose X-ray shading • Specimens were obtained uniform and well-defined in shape and concentration by printing. • Direct visualization and determination of shading in such specimens using the camera

  9. Observation of X-ray shadings in synchrotron radiation-total reflection X-ray fluorescence using a color X-ray camera

    Energy Technology Data Exchange (ETDEWEB)

    Fittschen, Ursula Elisabeth Adriane, E-mail: ursula.fittschen@chemie.uni-hamburg.de [Institut für Anorganische und Angewandte Chemie, Universität Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Menzel, Magnus [Institut für Anorganische und Angewandte Chemie, Universität Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Scharf, Oliver [IfG Institute for Scientific Instruments GmbH, Berlin (Germany); Radtke, Martin; Reinholz, Uwe; Buzanich, Günther [BAM Federal Institute of Materials Research and Testing, Berlin (Germany); Lopez, Velma M.; McIntosh, Kathryn [Los Alamos National Laboratory, Los Alamos, NM (United States); Streli, Christina [Atominstitut, TU Wien, Vienna (Austria); Havrilla, George Joseph [Los Alamos National Laboratory, Los Alamos, NM (United States)

    2014-09-01

    Absorption effects and the impact of specimen shape on TXRF analysis has been discussed intensively. Model calculations indicated that ring shaped specimens should give better results in terms of higher counts per mass signals than filled rectangle or circle shaped specimens. One major reason for the difference in signal is shading effects. Full field micro-XRF with a color X-ray camera (CXC) was used to investigate shading, which occurs when working with small angles of excitation as in TXRF. The device allows monitoring the illuminated parts of the sample and the shaded parts at the same time. It is expected that sample material hit first by the primary beam shade material behind it. Using the CXC shading could be directly visualized for the high concentration specimens. In order to compare the experimental results with calculation of the shading effect the generation of controlled specimens is crucial. This was achieved by “drop on demand” technology. It allows generating uniform, microscopic deposits of elements. The experimentally measured shadings match well with those expected from calculation. - Highlights: • Use of a color X-ray camera and drop on demand printing to diagnose X-ray shading • Specimens were obtained uniform and well-defined in shape and concentration by printing. • Direct visualization and determination of shading in such specimens using the camera.

  10. SASfit: A comprehensive tool for small-angle scattering data analysis

    CERN Document Server

    Breßler, Ingo; Thünemann, Andreas F

    2015-01-01

    Small-angle X-ray and neutron scattering experiments are used in many fields of the life sciences and condensed matter research to obtain answers to questions about the shape and size of nano-sized structures, typically in the range of 1 to 100 nm. It provides good statistics for large numbers of structural units for short measurement times. With the ever-increasing quantity and quality of data acquisition, the value of appropriate tools that are able to extract valuable information is steadily increasing. SASfit has been one of the mature programs for small-angle scattering data analysis available for many years. We describe the basic data processing and analysis work-flow along with recent developments in the SASfit program package (version 0.94.6). They include (i) advanced algorithms for reduction of oversampled data sets (ii) improved confidence assessment in the optimized model parameters and (iii) a flexible plug-in system for custom user-provided models. A scattering function of a mass fractal model o...

  11. Nanostructure surveys of macroscopic specimens by small-angle scattering tensor tomography

    Science.gov (United States)

    Liebi, Marianne; Georgiadis, Marios; Menzel, Andreas; Schneider, Philipp; Kohlbrecher, Joachim; Bunk, Oliver; Guizar-Sicairos, Manuel

    2015-11-01

    The mechanical properties of many materials are based on the macroscopic arrangement and orientation of their nanostructure. This nanostructure can be ordered over a range of length scales. In biology, the principle of hierarchical ordering is often used to maximize functionality, such as strength and robustness of the material, while minimizing weight and energy cost. Methods for nanoscale imaging provide direct visual access to the ultrastructure (nanoscale structure that is too small to be imaged using light microscopy), but the field of view is limited and does not easily allow a full correlative study of changes in the ultrastructure over a macroscopic sample. Other methods of probing ultrastructure ordering, such as small-angle scattering of X-rays or neutrons, can be applied to macroscopic samples; however, these scattering methods remain constrained to two-dimensional specimens or to isotropically oriented ultrastructures. These constraints limit the use of these methods for studying nanostructures with more complex orientation patterns, which are abundant in nature and materials science. Here, we introduce an imaging method that combines small-angle scattering with tensor tomography to probe nanoscale structures in three-dimensional macroscopic samples in a non-destructive way. We demonstrate the method by measuring the main orientation and the degree of orientation of nanoscale mineralized collagen fibrils in a human trabecula bone sample with a spatial resolution of 25 micrometres. Symmetries within the sample, such as the cylindrical symmetry commonly observed for mineralized collagen fibrils in bone, allow for tractable sampling requirements and numerical efficiency. Small-angle scattering tensor tomography is applicable to both biological and materials science specimens, and may be useful for understanding and characterizing smart or bio-inspired materials. Moreover, because the method is non-destructive, it is appropriate for in situ measurements and

  12. Nanostructure surveys of macroscopic specimens by small-angle scattering tensor tomography.

    Science.gov (United States)

    Liebi, Marianne; Georgiadis, Marios; Menzel, Andreas; Schneider, Philipp; Kohlbrecher, Joachim; Bunk, Oliver; Guizar-Sicairos, Manuel

    2015-11-19

    The mechanical properties of many materials are based on the macroscopic arrangement and orientation of their nanostructure. This nanostructure can be ordered over a range of length scales. In biology, the principle of hierarchical ordering is often used to maximize functionality, such as strength and robustness of the material, while minimizing weight and energy cost. Methods for nanoscale imaging provide direct visual access to the ultrastructure (nanoscale structure that is too small to be imaged using light microscopy), but the field of view is limited and does not easily allow a full correlative study of changes in the ultrastructure over a macroscopic sample. Other methods of probing ultrastructure ordering, such as small-angle scattering of X-rays or neutrons, can be applied to macroscopic samples; however, these scattering methods remain constrained to two-dimensional specimens or to isotropically oriented ultrastructures. These constraints limit the use of these methods for studying nanostructures with more complex orientation patterns, which are abundant in nature and materials science. Here, we introduce an imaging method that combines small-angle scattering with tensor tomography to probe nanoscale structures in three-dimensional macroscopic samples in a non-destructive way. We demonstrate the method by measuring the main orientation and the degree of orientation of nanoscale mineralized collagen fibrils in a human trabecula bone sample with a spatial resolution of 25 micrometres. Symmetries within the sample, such as the cylindrical symmetry commonly observed for mineralized collagen fibrils in bone, allow for tractable sampling requirements and numerical efficiency. Small-angle scattering tensor tomography is applicable to both biological and materials science specimens, and may be useful for understanding and characterizing smart or bio-inspired materials. Moreover, because the method is non-destructive, it is appropriate for in situ measurements and

  13. X-ray Echo Spectroscopy

    Science.gov (United States)

    Shvyd'ko, Yuri

    2016-02-01

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >108 ) with broadband ≃5 - 13 meV dispersing systems are introduced featuring more than 103 signal enhancement. The technique is general, applicable in different photon frequency domains.

  14. X-ray echo spectroscopy

    CERN Document Server

    Shvyd'ko, Yuri

    2015-01-01

    X-ray echo spectroscopy, a counterpart of neutron spin-echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a point-like x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x-rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1--0.02-meV ultra-high-resolution IXS applications (resolving power $> 10^8$) with broadband $\\simeq$~5--13~meV dispersing systems are introduced featuring more than $10^3$ signal e...

  15. X-ray Echo Spectroscopy.

    Science.gov (United States)

    Shvyd'ko, Yuri

    2016-02-26

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >10^{8}) with broadband ≃5-13  meV dispersing systems are introduced featuring more than 10^{3} signal enhancement. The technique is general, applicable in different photon frequency domains.

  16. Sub-pixel porosity revealed by x-ray scatter dark field imaging

    Science.gov (United States)

    Revol, V.; Jerjen, I.; Kottler, C.; Schütz, P.; Kaufmann, R.; Lüthi, T.; Sennhauser, U.; Straumann, U.; Urban, C.

    2011-08-01

    X-ray scatter dark field imaging based on the Talbot-Lau interferometer allows for the measurement of ultra-small angle x-ray scattering. The latter is related to the variations in the electron density in the sample at the sub- and micron-scale. Therefore, information on features of the object below the detector resolution can be revealed. In this article, it is demonstrated that scatter dark field imaging is particularly adapted to the study of a material's porosity. An interferometer, optimized for x-ray energies around 50 keV, enables the investigation of aluminum welding with conventional laboratory x-ray tubes. The results show an unprecedented contrast between the pool and the aluminum workpiece. Our conclusions are confirmed due to micro-tomographic three-dimensional reconstructions of the same object with a microscopic resolution.

  17. X-Ray Cross-Correlation Analysis of Disordered Ensembles of Particles: Potentials and Limitations

    Directory of Open Access Journals (Sweden)

    R. P. Kurta

    2013-01-01

    Full Text Available Angular X-ray cross-correlation analysis (XCCA is an approach to study the structure of disordered systems using the results of X-ray scattering experiments. In this paper we summarize recent theoretical developments related to the Fourier analysis of the cross-correlation functions. Results of our simulations demonstrate the application of XCCA to two- and three-dimensional (2D and 3D disordered ensembles of particles. We show that the structure of a single particle can be recovered using X-ray data collected from a 2D disordered system of identical particles. We also demonstrate that valuable structural information about the local structure of 3D systems, inaccessible from a standard small-angle X-ray scattering experiment, can be resolved using XCCA.

  18. Dental X-ray apparatus

    International Nuclear Information System (INIS)

    Intra-oral X-ray apparatus which reduces the number of exposures necessary to obtain panoramic dental radiographs is described in detail. It comprises an electron gun, a tubular target carrier projecting from the gun along the beam axis and carrying at its distal end a target surrounded by a shield of X-ray opaque material. This shield extends forward and laterally of the target and has surfaces which define a wedge or cone-shaped radiation pattern delimited vertically by the root tips of the patient's teeth. A film holder is located externally of the patient's mouth. A disposable member can fit on the target carrier to depress the patient's tongue out of the radiation pattern and to further shield the roof of the mouth. The electron beam can be magnetically deflected to change the X-ray beam direction. (author)

  19. Full-field and scanning microtomography based on parabolic refractive x-ray lenses

    Science.gov (United States)

    Schroer, C. G.; Kuhlmann, M.; Günzler, T. F.; Benner, B.; Kurapova, O.; Patommel, J.; Lengeler, B.; Roth, S. V.; Gehrke, R.; Snigirev, A.; Snigireva, I.; Stribeck, N.; Almendarez-Camarillo, A.; Beckmann, F.

    2006-08-01

    Hard x-ray full field and scanning microscopy both greatly benefit from recent advances in x-ray optics. In full field microscopy, for instance, rotationally parabolic refractive x-ray lenses can be used as objective lens in a hard x-ray microscope, magnifying an object onto a detector free of distortion. Using beryllium as lens material, a hard x-ray optical resolution of about 100 nm has been obtained in a field of view of more than 500 micrometers. Further improvement of the spatial resolution to below 50 nm is expected. By reconstructing the sample from a series of micrographs recorded from different perspectives, tomographic imaging with a resolution well below one micrometer was achieved. The technique is demonstrated using a microchip as test sample. In scanning microscopy and tomography, the sample is scanned through a hard x-ray microbeam. Different hard x-ray analytical techniques can be exploited as contrast mechanism, such as x-ray fluorescence, absorption, or scattering. In tomographic scanning mode, they yield for example local elemental, chemical, or structural information from inside a specimen. At synchrotron radiation sources, a small and intensive microbeam can be generated by imaging the source onto the sample position in a strongly reducing geometry, e.g., by parabolic refractive x-ray lenses. With nanofocusing refractive x-ray lenses, a lateral beam size of 50 nm was reached. As an example for scanning tomography, we consider tomographic small angle x-ray scattering (SAXS-tomography), reconstructing a series of SAXS patterns related to small volume elements inside a polymer rod made by injection moulding.

  20. Very faint X-ray binaries with XMM-Newton

    Science.gov (United States)

    Armas Padilla, M.

    2016-06-01

    A population of very faint X-ray binaries has been discovered in the last years thanks to the improvement in sensitivity and resolution of the new generations of X-ray missions. These systems show anomalously low luminosities, below 10^{36} ergs/sec, challenging our understanding of accretion physics and binary evolution models, and thereby opening new windows for both observational and theoretical work on accretion onto compact objects. XMM-Newton is playing a crucial role in the study of this dim family of objects thanks to its incomparable spectral capabilities at low luminosities. I will review the state-of-the-art of the field and present our XMM results in both black hole and neutron star objects. Finally, I will discuss the possibilities that the new generation of X-ray telescopes offer for this research line.

  1. X-ray imaging: Perovskites target X-ray detection

    Science.gov (United States)

    Heiss, Wolfgang; Brabec, Christoph

    2016-05-01

    Single crystals of perovskites are currently of interest to help fathom fundamental physical parameters limiting the performance of perovskite-based polycrystalline solar cells. Now, such perovskites offer a technology platform for optoelectronic devices, such as cheap and sensitive X-ray detectors.

  2. Small angle elastic scattering of electrons by noble gas atoms

    International Nuclear Information System (INIS)

    In this thesis, measurements are carried out to obtain small angle elastic differential cross sections in order to check the validity of Kramers-Kronig dispersion relations for electrons scattered by noble gas atoms. First, total cross sections are obtained for argon, krypton and xenon. Next, a parallel plate electrostatic energy analyser for the simultaneous measurement of doubly differential cross section for small angle electron scattering is described. Also absolute differential cross sections are reported. Finally the forward dispersion relation for electron-helium collisions is dealt with. (Auth.)

  3. Small-angle anisotropies in the CMBR from active sources

    CERN Document Server

    Battye, R A

    1997-01-01

    We consider the effects of photon diffusion on the small-angle microwave background anisotropies due to active source models. We find that fluctuations created just before the time of last scattering allow anisotropy to be created on scales much smaller than allowed by standard Silk damping. Using simple models for string and texture structure functions as examples, we illustrate the differences in the angular power spectrum at scales of order a few arcminutes. In particular, we find that the Doppler peak heights are modified by 10-50% and the small-angle fall-off is power law rather than exponential.

  4. X-ray hot plasma diagnostics

    International Nuclear Information System (INIS)

    X-ray plasma emission study is powerful diagnostic tool of hot plasmas. In this review article the main techniques of X-ray plasma emission measurement are shortly presented: X-ray spectrometry using absorbent filters, crystal and grating spectrometers, imaging techniques using pinhole cameras, X-ray microscopes and Fresnel zone plate cameras, X-ray plasma emission calorimetry. Advances in these techniques with examples for different hot plasma devices are also presentes. (author)

  5. Time-resolved and in-situ X-ray scattering methods beyond photoactivation: Utilizing high-flux X-ray sources for the study of ubiquitous non-photoactive proteins.

    Science.gov (United States)

    Jain, Rohit; Techert, Simone

    2016-01-01

    X-ray scattering technique, comprising of small-angle/wide-angle X-ray scattering (SAXS/WAXS) techniques is increasingly used to characterize the structure and interactions of biological macromolecules and their complexes in solution. It is a method of choice to characterize the flexible, partially folded and unfolded protein systems. X-ray scattering is the last resort for proteins that cannot be investigated by crystallography or NMR and acts as a complementary technique with different biophysical techniques to answer challenging scientific questions. The marriage of the X-ray scattering technique with the fourth dimension "time" yields structural dynamics and kinetics information for protein motions in hierarchical timescales from picoseconds to days. The arrival of the high-flux X-ray beam at third generation synchrotron sources, exceptional X-ray optics, state-of-the-art detectors, upgradation of X-ray scattering beamlines with microfluidics devices and advanced X-ray scattering data analysis procedures are the important reasons behind the shining years of X-ray scattering technique. The best days of the X-ray scattering technique are on the horizon with the advent of the nanofocus X-ray scattering beamlines and fourth generation X-ray lightsources, i.e., free electron lasers (XFELs). Complementary to the photon-triggered time-resolved X-ray scattering techniques, we will present an overview of the time-resolved and in-situ X-ray scattering techniques for structural dynamics of ubiquitous non-photoactive proteins.

  6. Magnetism in heterogeneous thin film systems: Resonant X-ray scattering studies

    CERN Document Server

    Kortright, J B; Bader, S D; Hellwig, O; Marguiles, D T; Fullerton, E E

    2003-01-01

    Magnetic and chemical heterogeneity are common in a broad range of magnetic thin film systems. Emerging resonant soft X-ray scattering techniques are well suited to resolve such heterogeneity at relevant length scales. Resonant X-ray magneto-optical Kerr effect measurements laterally average over heterogeneity but can provide depth resolution in different ways, as illustrated in measurements resolving reversible and irreversible changes in different layers of exchange-spring heterostructures. Resonant small-angle scattering measures in-plane heterogeneity and can resolve magnetic and chemical scattering sources in different ways, as illustrated in measurements of granular alloy recording media.

  7. X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    The seventh edition of Philips' Review of Literature on x-ray fluorescence spectrometry starts with a list of conference proceedings on the subject, organised by the Philips organisation at regular intervals in various European countries. It is followed by a list of bulletins. The bibliography is subdivided according to spectra, equipment, applications and absorption analysis

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Images related to X-ray (Radiography) - Bone About this Site RadiologyInfo.org is produced by: Please note ... you can search the ACR-accredited facilities database . This website does not provide cost information. The costs ...

  9. X-ray backscatter imaging

    Science.gov (United States)

    Dinca, Dan-Cristian; Schubert, Jeffrey R.; Callerame, J.

    2008-04-01

    In contrast to transmission X-ray imaging systems where inspected objects must pass between source and detector, Compton backscatter imaging allows both the illuminating source as well as the X-ray detector to be on the same side of the target object, enabling the inspection to occur rapidly and in a wide variety of space-constrained situations. A Compton backscatter image is similar to a photograph of the contents of a closed container, taken through the container walls, and highlights low atomic number materials such as explosives, drugs, and alcohol, which appear as especially bright objects by virtue of their scattering characteristics. Techniques for producing X-ray images based on Compton scattering will be discussed, along with examples of how these systems are used for both novel security applications and for the detection of contraband materials at ports and borders. Differences between transmission and backscatter images will also be highlighted. In addition, tradeoffs between Compton backscatter image quality and scan speed, effective penetration, and X-ray source specifications will be discussed.

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Bone ...

  11. X-Ray Diffractive Optics

    Science.gov (United States)

    Dennis, Brian; Li, Mary; Skinner, Gerald

    2013-01-01

    X-ray optics were fabricated with the capability of imaging solar x-ray sources with better than 0.1 arcsecond angular resolution, over an order of magnitude finer than is currently possible. Such images would provide a new window into the little-understood energy release and particle acceleration regions in solar flares. They constitute one of the most promising ways to probe these regions in the solar atmosphere with the sensitivity and angular resolution needed to better understand the physical processes involved. A circular slit structure with widths as fine as 0.85 micron etched in a silicon wafer 8 microns thick forms a phase zone plate version of a Fresnel lens capable of focusing approx. =.6 keV x-rays. The focal length of the 3-cm diameter lenses is 100 microns, and the angular resolution capability is better than 0.1 arcsecond. Such phase zone plates were fabricated in Goddard fs Detector Development Lab. (DDL) and tested at the Goddard 600-microns x-ray test facility. The test data verified that the desired angular resolution and throughput efficiency were achieved.

  12. X-ray film processing

    International Nuclear Information System (INIS)

    X-ray films have to be highly sensitive, for radiation protection reasons. The films used in radiology are coated on both sides with a photosensitive emulsion. This applies to all dental films. Their properties and the development of the different exposed films are explained. (DG)

  13. X-rays and magnetism.

    Science.gov (United States)

    Fischer, Peter; Ohldag, Hendrik

    2015-09-01

    Magnetism is among the most active and attractive areas in modern solid state physics because of intriguing phenomena interesting to fundamental research and a manifold of technological applications. State-of-the-art synthesis of advanced magnetic materials, e.g. in hybrid structures paves the way to new functionalities. To characterize modern magnetic materials and the associated magnetic phenomena, polarized x-rays have emerged as unique probes due to their specific interaction with magnetic materials. A large variety of spectroscopic and microscopic techniques have been developed to quantify in an element, valence and site-sensitive way properties of ferro-, ferri-, and antiferromagnetic systems, such as spin and orbital moments, and to image nanoscale spin textures and their dynamics with sub-ns time and almost 10 nm spatial resolution. The enormous intensity of x-rays and their degree of coherence at next generation x-ray facilities will open the fsec time window to magnetic studies addressing fundamental time scales in magnetism with nanometer spatial resolution. This review will give an introduction into contemporary topics of nanoscale magnetic materials and provide an overview of analytical spectroscopy and microscopy tools based on x-ray dichroism effects. Selected examples of current research will demonstrate the potential and future directions of these techniques.

  14. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... over time. top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and easiest ... cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk. ...

  15. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... over time. top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and easiest ... evaluation. National and international radiology protection organizations continually review and update the technique standards used by radiology ...

  16. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... for more information about pregnancy and x-rays. A Word About Minimizing Radiation Exposure Special care is ... encourage linking to this site. × Recommend RadiologyInfo to a friend Send to (friend's e-mail address): From ( ...

  17. Probing magnetar magnetosphere through X-ray polarization measurements

    Science.gov (United States)

    Taverna, R.; Muleri, F.; Turolla, R.; Soffitta, P.; Fabiani, S.; Nobili, L.

    2014-02-01

    The study of magnetars is of particular relevance since these objects are the only laboratories where the physics in ultra-strong magnetic fields can be directly tested. Until now, spectroscopic and timing measurements at X-ray energies in soft gamma repeaters and anomalous X-ray pulsars (AXPs) have been the main source of information about the physical properties of a magnetar and of its magnetosphere. Spectral fitting in the ˜0.5-10 keV range allowed us to validate the `twisted magnetosphere' model, probing the structure of the external field and estimating the density and velocity of the magnetospheric currents. Spectroscopy alone, however, may fail in disambiguating the two key parameters governing magnetospheric scattering (the charge velocity and the twist angle) and is quite insensitive to the source geometry. X-ray polarimetry, on the other hand, can provide a quantum leap in the field by adding two extra observables, the linear polarization degree and the polarization angle. Using the bright AXP 1RXS J170849.0-400910 as a template, we show that phase-resolved polarimetric measurements can unambiguously determine the model parameters, even with a small X-ray polarimetry mission carrying modern photoelectric detectors and existing X-ray optics. We also show that polarimetric measurements can pinpoint vacuum polarization effects and thus provide indirect evidence for ultra-strong magnetic fields.

  18. High-Resolution X-ray Emission and X-ray Absorption Spectroscopy

    OpenAIRE

    de Groot, F. M. F.

    2001-01-01

    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 process. Section II discusses 1s X-ray absorption, i.e., the K edges, and section III deals with 2p X-ray absorption, the L edges. X-ray emission is discussed in, respectively, the L edges. X-ray emis...

  19. Progress in small angle neutron scattering activities in Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Abdul Aziz Bin Mohamed; Azali Bin Muhamad; Shukri Bin Mohd [Malaysian Institute for Nuclear Technology Research (MINT), Bangi, Kajang (Malaysia)

    1999-10-01

    The current status of SANS (Small Angle Neutron Scattering facility) activities in Malaysia has been presented. Many works need to be done for system improvement before the system can be confidently used as one of effective quality control tools in materials production and engineering sectors. (author)

  20. Neutron imaging and small angle neutron scattering instruments at KUR

    International Nuclear Information System (INIS)

    We review the neutron imaging (NI) and small-angle neutron scattering (SANS) instruments at KUR, Kumatori, Osaka, Japan. There are two NI and one SANS instruments. The both instruments are compact and used flexibly. Some challenging experiments taking advantage of low neutron fluence are described. The feature of KUR is also described briefly. (author)