WorldWideScience

Sample records for angle x-ray studies

  1. 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)

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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....

  8. Angle-Dispersive X-ray Diffraction Study of Energetic Materials

    Science.gov (United States)

    Gump, Jared; Peiris, Suhithi

    2004-03-01

    Determining thermodynamic properties of energetic materials is important to the United States Navy for predicting the performance of new energetic formulations. This study uses angle dispersive x-ray diffraction performed at Cornell University's High Energy Synchrotron Source to obtain several isothermal equations of state of energetic materials, such as HMX and CL-20. Both non-hydrostatic and hydrostatic conditions were examined at room temperature. Pressures of up to 6GPa were achieved using diamond anvil cells. The bulk modulus and its first pressure derivative were determined by fitting the data to the Birch-Murnaghan equation of state formalism. Experimental data will be compared to ab-initio HF calculations and MD simulations.

  9. Study of human blood and hemocomponents irradiated by low angle x ray scattering (LAXS)

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Nivia G. Villela; Barroso, Regina C. [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Inst. de Fisica. Dept. de Fisica Aplicada e Termodinamica], e-mail: nitatag@gmail.com; Mota, Carla L.S.; Almeida, Andre P.; Azeredo, Soraia R.; Braz, Delson [Coordenacao dos Programas de Pos-graduacao em Engenharia (COPPE/UFRJ), RJ (Brazil). Lab. de Instrumentacao Nuclear], e-mail: delson@lin.ufrj.br

    2009-07-01

    Irradiation of blood and blood components is currently practiced in developed and in a few developing countries. The main purpose of this process is the prevention of graft versus host disease in immunodeficient patients. The Food and Drug Administration recommends a dose range of 15 Gy to 25 Gy for these blood components. When x-ray photons are scattered from biological samples, their angular distribution shows one or more peaks in the forward direction of scattering. These peaks are characteristic for the investigated samples. Due to its wide range of biological and medical applications, low-angle x-ray scattering has attracted the attention of many authors. Thus in this present work was studied the possible variations in scattering profiles due to the irradiation when the gender of patients was considered. Fresh blood specimens were obtained from volunteers using vacutainer tubes containing EDTA, at the Dr. Eliel Figueiredo Laboratory, Rio de Janeiro. All the samples were lyophilized for 48 hours in a freeze drier in order to remove the water. The scattering measurements were carried out in e-2e reflection geometry using a powder diffractometer Shimadzu XRD- 6000. The measured characterization parameters for LAXS were associated with epidemiological data (gender). The mean values of the different parameters were compared using the Students's t-test for each characterization parameters. The scattering profiles from plasma and formed elements are characterized by the presence of two peaks in the forward direction of scattering. For epidemiological data (gender) analyzed was not found significant changes in the mostly of characterization parameters (p>0.05). (author)

  10. 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).

  11. 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...

  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. 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...

  14. 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

  15. 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.

  16. 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).

  17. 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)

  18. 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).

  19. 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.

  20. 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.

  1. 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...

  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. 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.

  4. The atomic scale structure of CXV carbon: wide-angle x-ray scattering and modeling studies

    Science.gov (United States)

    Hawelek, L.; Brodka, A.; Dore, J. C.; Honkimaki, V.; Burian, A.

    2013-11-01

    The disordered structure of commercially available CXV activated carbon produced from finely powdered wood-based carbon has been studied using the wide-angle x-ray scattering technique, molecular dynamics and density functional theory simulations. The x-ray scattering data has been converted to the real space representation in the form of the pair correlation function via the Fourier transform. Geometry optimizations using classical molecular dynamics based on the reactive empirical bond order potential and density functional theory at the B3LYP/6-31g* level have been performed to generate nanoscale models of CXV carbon consistent with the experimental data. The final model of the structure comprises four chain-like and buckled graphitic layers containing a small percentage of four-fold coordinated atoms (sp3 defects) in each layer. The presence of non-hexagonal rings in the atomic arrangement has been also considered.

  5. 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.

  6. 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...

  7. Angle-dependent hard X-ray photoemission study of Nb hydride formation in high-pressure supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Soda, Kazuo, E-mail: j45880a@cc.nagoya-u.ac.jp [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kondo, Hiroki; Yamaguchi, Kanta; Kato, Masahiko [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Shiraki, Tatsuhito; Niwa, Ken; Kusaba, Keiji; Hasegawa, Masashi [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Xeniya, Kozina; Ikenaga, Eiji [Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2015-09-15

    Highlights: • Nb hydrides in 10-GPa supercritical water are studied by photoelectron spectroscopy. • The hydride components of the Nb 3d core-level spectra are increased with the depth. • The bulk valence-band spectrum shows a split band due to the Nb–H bond formation. • The hydrides are formed in the bulk and their surfaces are covered with Nb oxides. - Abstract: Nb hydrides formation in 10-GPa supercritical water has been investigated by angle-dependent micro-beam hard X-ray photoemission spectroscopy. In the Nb 3d core-level spectra, Nb hydride components are found in the slightly high binding energy side of the metallic components, and the oxide ones are observed even though little oxides are recognized in X-ray diffraction patterns. Obtained emission-angle dependence of the Nb 3d core-level spectra of Nb hydride specimens shows that the Nb hydride components increase with the emission angle decreased i.e. the sampling depth increased, while the oxide ones decrease. The bulk valence-band spectrum is obtained by decomposing the measured valence-band spectra into a bulk and surface components with use of the emission-angle dependence of the core-level and valence-band spectra; it consists of two bands. This implies the Nb–H chemical bond formation and Nb in an oxidation state, consistent with reported band structure calculations and the observed core-level chemical shifts. Thus it is confirmed by valence-band and core-level photoelectron spectroscopy that the Nb hydrides are formed inside the specimen, irrespective to the well-known high oxidation ability of supercritical water.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Glancing angle synchrotron X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Cernik, R.J. [Daresbury Lab., Warrington, WA (United States)

    1996-09-01

    This paper describes in basic detail some of the techniques that can be used to study thin films and surfaces. These are all in the X-ray region and cover reflectivity, diffraction form polycrystalline films, textured films and single crystal films. Other effects such as fluorescence and diffuse scattering are mentioned but not discussed in detail. Two examples of the reflectivity from multilayers and the diffraction from iron oxide films are discussed. The advantages of the synchrotron for these studies is stressed and the experimental geometries that can be employed are described i detail. A brief bibliography is provided at the end to accompany this part of the 1996 Frascati school.

  15. 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)

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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...

  1. Combined in situ small and wide angle X-ray scattering studies of TiO2 nano-particle annealing to 1023 K

    DEFF Research Database (Denmark)

    Kehres, Jan; Andreasen, Jens Wenzel; Krebs, Frederik C;

    2010-01-01

    Combined in situ small- and wide-angle X-ray scattering (SAXS/WAXS) studies were performed in a recently developed laboratory setup to investigate the dynamical properties of dry oleic acid-capped titanium dioxide nanorods during annealing in an inert gas stream in a temperature interval of 298-1...

  2. 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...

  3. 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)

  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. 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.

  6. 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.)

  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. X-ray diffraction at Bragg angles around π/2

    International Nuclear Information System (INIS)

    X-ray diffraction at Bragg angles around π/2 is studied from the theoretical and experimental points of view. The proposed corrections to the dynamical theory in the θβ ≅ π/2 cases, has been reviewed showing the equivalence between two formalisms leading to a corrected expression for the dependence of the angular parameter y with the angle of incidence. An expression for y valid in the conventional and θ β ≅ π/2 cases has been obtained. A general expression for Bragg law and for energy resolution after a Bragg diffraction was also deduced. (author)

  10. 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.

  11. 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.

  12. 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.

  13. Watching Nanoparticles Form: An In Situ (Small-/Wide-Angle X-ray Scattering/Total Scattering) Study of the Growth of Yttria-Stabilised Zirconia in Supercritical Fluids

    DEFF Research Database (Denmark)

    Tyrsted, Christoffer; Pauw, Brian; Jensen, Kirsten Marie Ørnsbjerg;

    2012-01-01

    Understanding nanoparticle formation reactions requires multitechnique in situ characterisation, since no single characterisation technique provides adequate information. Here, the first combined small-angle X-ray scattering (SAXS)/wide-angle X-ray scattering (WAXS)/total-scattering study...

  14. 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

  15. 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.

  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. 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

  18. ``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

  19. 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

  20. 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...

  1. 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.

  2. 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...

  3. 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.

  4. Soft x rays for radiobiological studies

    International Nuclear Information System (INIS)

    Lethal effects and chromosome aberrations induced in cells exposed to low energy (soft) X rays demonstrated that these relatively low energy X rays are just as effective as those of higher energy for radiobiological studies, and even more effective for irradiating cultured mammalian cells than laboratory animals. (author)

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Dynamic angle selection in X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Dabravolski, Andrei, E-mail: andrei.dabravolski@uantwerpen.be [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Batenburg, Kees Joost, E-mail: joost.batenburg@uantwerpen.be [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Centrum Wiskunde and Informatica (CWI), Science Park 123, 1098 XG Amsterdam (Netherlands); Sijbers, Jan, E-mail: jan.sijbers@uantwerpen.be [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium)

    2014-04-01

    Highlights: • We propose the dynamic angle selection algorithm for CT scanning. • The approach is based on the concept of information gain over a set of solutions. • Projection angles are selected based on the already available projection data. • The approach can lead to more accurate results from fewer projections. - Abstract: In X-ray tomography, a number of radiographs (projections) are recorded from which a tomogram is then reconstructed. Conventionally, these projections are acquired equiangularly, resulting in an unbiased sampling of the Radon space. However, especially in case when only a limited number of projections can be acquired, the selection of the angles has a large impact on the quality of the reconstructed image. In this paper, a dynamic algorithm is proposed, in which new projection angles are selected by maximizing the information gain about the object, given the set of possible new angles. Experiments show that this approach can select projection angles for which the accuracy of the reconstructed image is significantly higher compared to the standard angle selections schemes.

  11. Cell survival studies using ultrasoft x rays

    International Nuclear Information System (INIS)

    Cell survival was studied for V79 hamster, 10T1/2 mouse, and human skin fibroblast cell lines, using carbon K (0.28 keV), copper K (8.0 keV), and 250 kVp x rays. Because of the rapid attenuation of the carbon x rays, cellular dimensions at the time of exposure were measured using optical and electron microscopy, and frequency distributions of mean dose absorbed by the cell nucleus were obtained. The results indicate that the differences in cell killing between ultra-soft and hard x rays may depend on the nuclear thickness of the cells. Studies of the effects of hypoxia on V79 and 10T1/2 cells using carbon K, aluminum K (1.5 keV), and copper K x rays show decreasing OER values with decreasing x-ray energy and no difference between the two cell lines. Age response studies with V79 cells show similar cell-cycle variation of survival for carbon K and aluminum K x rays as for hard x rays

  12. X-ray tubes study and design

    CERN Document Server

    Sardari, D

    1990-01-01

    This thesis contain both theoretical and experimental works. Theoretical aspect includes X-Ray tubes case study and design principles, in the introduced design process, anode-cathode distance, vacuum needed, filament size, anode face angle and shape and size of focusing electrodes can be found. A method for specification of tungsten lager thickness on anode is also introduced. Using computer simulation, electron trajectory between cathode-anode is obtained, This work is presented in the first International Conference on Control and Modeling, Tehran, 1990. Experimental work contains manufacturing more than 10 tubes and test each of them. One of these tubes can with stand up to 50 KV. Filament can be heated by passing a 2.1 A current. In these conditions anode current is 1.2 m A. Using this tube, some radiographs have been taken.

  13. 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.

  14. Low-angle X-ray scattering from spices

    Energy Technology Data Exchange (ETDEWEB)

    Desouky, O.S. E-mail: omardesouky@yahoo.com; Ashour, Ahmed H.; Abdullah, Mohamed I.; Elshemey, Wael M

    2002-07-01

    Low-angle scattering of X-rays is characterized by the presence of one or more peaks in the forward direction of scattering. These peaks are due to the interference of photons coherently scattered from the molecules of the medium. Thus these patterns are closely linked to the molecular structure of the investigated medium. In this work, low-angle X-ray scattering (LAXS) profiles of five spices; pimpinella anisum (anise), coriandrum sativum (coriander), cuminum cyminum (cumin), foenculum vulgare (fennel) and nigella sativa (nigella or black cumin) are presented after extensive measurements. It is found that all spices exhibit one characteristic peak at a scattering angle around 10 deg. This is equivalent to a value x=0.0565 A{sup -1}, where x=sin({theta}/2)/{lambda}. The full width at half maximum (FWHM) of this peak is found to be characteristic for each type of the investigated spices. The possibility to detect the irradiation of these spices from their LAXS profiles is also examined after 10, 20, 30 and 40 kGy doses of gamma radiation. Except for anise, coriander and cumin at 40 kGy, there are no detectable deviations from the control samples in the scattering profiles of irradiated samples. These results comply with the recommendations of the FDA (US Food and Drug Administration) which defines 30 kGy as the maximum dose for irradiation of spices. The present technique could be used to detect over-irradiation, which causes damage to the molecular structure of some spices.

  15. 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.

  16. 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.

  17. 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

  18. Ultrasmall-angle X-ray scattering analysis of photonic crystal structure

    NARCIS (Netherlands)

    Abramova, V.V.; Sinitskii, A.S.; Grigoryeva, N.A.; Grigoriev, S.V.; Belov, D.V.; Petukhov, A.V.; Mistonov, A.A.; Vasilieva, A.V.; Tretyakov, Y.D.

    2009-01-01

    The results of an ultrasmall angle X ray scattering study of iron(III) oxide inverse opal thin films are presented. The photonic crystals examined are shown to have fcc structure with amount of stacking faults varying among the samples. The method used in this study makes it possible to easily disti

  19. 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

  20. 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...

  1. 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.

  2. 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)

  3. Radiobiological studies using gamma and x rays.

    Energy Technology Data Exchange (ETDEWEB)

    Potter, Charles Augustus; Longley, Susan W.; Scott, Bobby R.; Lin, Yong; Wilder, Julie; Hutt, Julie A.; Padilla, Mabel T.; Gott, Katherine M.

    2013-02-01

    There are approximately 500 self-shielded research irradiators used in various facilities throughout the U.S. These facilities use radioactive sources containing either 137Cs or 60Co for a variety of biological investigations. A report from the National Academy of Sciences[1] described the issues with security of particular radiation sources and the desire for their replacement. The participants in this effort prepared two peer-reviewed publications to document the results of radiobiological studies performed using photons from 320-kV x rays and 137Cs on cell cultures and mice. The effectiveness of X rays was shown to vary with cell type.

  4. 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).

  5. X-ray studies of multilayer semiconductors using synchrotron radiation

    Science.gov (United States)

    Huang, Shiwen

    X-ray scattering and absorption techniques utilizing synchrotron radiation have been used to study a variety of multilayer semiconductors. The angular-dependent x-ray scattering at grazing incidence angles (grazing incidence x-ray scattering, GIXS) provides structural information of interfaces in these materials, such as rms interfacial roughness, cross- and lateral-correlation lengths, etc. Long-range order structures in material are probed by large-angle scattering (x-ray diffraction), in which strain and lattice constant as well as crystallinity of the epilayers are measured. Local structural variations in materials including local bond length, coordination number, and local disorder are obtained quantitatively by examining the modulation in the x-ray absorption spectrum some 40 eV above the absorption edge (extended x-ray absorption fine structure, EXAFS). Materials studied in the present work are SiGe/Si heterostructures, MnAs/GaAs ferromagnetic-semiconductor films, solar cell films, ZnSe-based II-VI semiconductor thin films, InGaAs/GaAs and GaAs/AlAs superlattices. Results obtained have shown (i) evidence for strain-induced surface/interface morphology variations in SiGe/Si heterostructures, (ii) template-dependent microstructures in MnAs/GaAs, (iii) changes in interface structures for films of different formations in solar cell films, (iv) differences between samples prepared by different epitaxial growth methods in II-VI semiconductor films, (v) observation of lateral structural ordering in one of the InGaAs/GaAs superlattices, (vi) differences in interfacial microstructures between MBE-grown samples with different interrupts in GaAs/AlAs superlattices. Most of all, x- rays are found to be a very useful nondestructive tool for probing microscopic structures in various multilayer semiconductor materials.

  6. 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...

  7. 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).

  8. Laser-based X-ray and electron source for X-ray fluorescence studies

    Science.gov (United States)

    Valle Brozas, F.; Crego, A.; Roso, L.; Peralta Conde, A.

    2016-08-01

    In this work, we present a modification to conventional X-rays fluorescence using electrons as excitation source and compare it with the traditional X-ray excitation for the study of pigments. For this purpose, we have constructed a laser-based source capable to produce X-rays as well as electrons. Because of the large penetration depth of X-rays, the collected fluorescence signal is a combination of several material layers of the artwork under study. However, electrons are stopped in the first layers, allowing a more superficial analysis. We show that the combination of both excitation sources can provide extremely valuable information about the structure of the artwork.

  9. Arbutin: Isolation, X-ray structure and computional studies

    Science.gov (United States)

    Nycz, Jacek E.; Malecki, Grzegorz; Morag, Monika; Nowak, Gerard; Ponikiewski, Lukasz; Kusz, Joachim; Switlicka, Anna

    2010-09-01

    Arbutin, an active component originated from Serratula quinquefolia for skin-whitening use and treating skin related allergic inflammation, was characterized by microanalysis, FTIR, UV-Vis, multinuclear NMR spectroscopy, and single crystal X-ray diffraction method. The geometries of the studied compound were optimized in singlet states using the density functional theory (DFT) method with B3LYP functional. Electronic spectra were calculated by TDDFT method. In general, the predicted bond lengths and angles are in a good agreement with the values based on the X-ray crystal structure data.

  10. 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.

  11. 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...

  12. 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.

  13. 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.

  14. 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...

  15. Effects of X-Ray Dose On Rhizosphere Studies Using X-Ray Computed Tomography.

    Directory of Open Access Journals (Sweden)

    Susan Zappala

    Full Text Available X-ray Computed Tomography (CT is a non-destructive imaging technique originally designed for diagnostic medicine, which was adopted for rhizosphere and soil science applications in the early 1980s. X-ray CT enables researchers to simultaneously visualise and quantify the heterogeneous soil matrix of mineral grains, organic matter, air-filled pores and water-filled pores. Additionally, X-ray CT allows visualisation of plant roots in situ without the need for traditional invasive methods such as root washing. However, one routinely unreported aspect of X-ray CT is the potential effect of X-ray dose on the soil-borne microorganisms and plants in rhizosphere investigations. Here we aimed to i highlight the need for more consistent reporting of X-ray CT parameters for dose to sample, ii to provide an overview of previously reported impacts of X-rays on soil microorganisms and plant roots and iii present new data investigating the response of plant roots and microbial communities to X-ray exposure. Fewer than 5% of the 126 publications included in the literature review contained sufficient information to calculate dose and only 2.4% of the publications explicitly state an estimate of dose received by each sample. We conducted a study involving rice roots growing in soil, observing no significant difference between the numbers of root tips, root volume and total root length in scanned versus unscanned samples. In parallel, a soil microbe experiment scanning samples over a total of 24 weeks observed no significant difference between the scanned and unscanned microbial biomass values. We conclude from the literature review and our own experiments that X-ray CT does not impact plant growth or soil microbial populations when employing a low level of dose (<30 Gy. However, the call for higher throughput X-ray CT means that doses that biological samples receive are likely to increase and thus should be closely monitored.

  16. Effect of Viewing Angle on Super-Soft-Source X-Ray Spectra

    Science.gov (United States)

    Ness, Jan-Uwe

    2012-09-01

    The advent of the X-ray grating spectrometers has given new momentum to the studies of Super-Soft-Source (SSS) X-ray spectra in high resolution. Earlier CCD-type spectra only allow determinations of effective temperatures while in the grating spectra, lines and continuum can be resolved. I have studied the X-ray grating spectra of eight classical novae during their SSS phase, two of them candidates for recurrent novae, two established recurrent novae, and four permanent SSSs including the prototypes Cal 83 and Cal 87. I discovered two categories of SSSs: those dominated by emission lines (SSSe) and by absorption line (SSSa). All spectra contain photospheric continuum emission, indicated by the shape of a blackbody. For the majority of SSSe, the inclination angle is known, which are all greater than 75 degrees. I argue that the SSSe are high-inclination systems in which photospheric X-ray emission from the central source is partially blocked and scattered via Thompson scattering, which preserves the spectral shape of the continuum. Since the electrons in the scattering medium move at high velocities, photospheric absorption lines are smeared out and are therefore not seen. Additional emission lines are produced by resonant line scattering. The fact that only high inclination systems show these effects of scattering, the scattering material must be concentrated to the ecliptic plane. While in permanent SSSs, the accretion disk can explain this behavior, this result implies that in novae, the reformation of the accretion disk has already progressed to an advanced stage during their SSS phase. I argue that also the novae in low-inclination angle systems possess a reformed accretion disk. The viewing angle dependence requires non-symmetrical modeling approaches. Early disk reformation can also explain high-amplitude variations that have frequently been observed during the early SSS phase.

  17. 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...

  18. 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.

  19. Liquid structure of acetic acid-water and trifluoroacetic acid-water mixtures studied by large-angle X-ray scattering and NMR.

    Science.gov (United States)

    Takamuku, Toshiyuki; Kyoshoin, Yasuhiro; Noguchi, Hiroshi; Kusano, Shoji; Yamaguchi, Toshio

    2007-08-01

    The structures of acetic acid (AA), trifluoroacetic acid (TFA), and their aqueous mixtures over the entire range of acid mole fraction xA have been investigated by using large-angle X-ray scattering (LAXS) and NMR techniques. The results from the LAXS experiments have shown that acetic acid molecules mainly form a chain structure via hydrogen bonding in the pure liquid. In acetic acid-water mixtures hydrogen bonds of acetic acid-water and water-water gradually increase with decreasing xA, while the chain structure of acetic acid molecules is moderately ruptured. Hydrogen bonds among water molecules are remarkably formed in acetic acid-water mixtures at xATFA molecules form not a chain structure but cyclic dimers through hydrogen bonding in the pure liquid. In TFA-water mixtures O...O hydrogen bonds among water molecules gradually increase when xA decreases, and hydrogen bonds among water molecules are significantly formed in the mixtures at xATFA molecules are considerably dissociated to hydrogen ions and trifluoroacetate in the mixtures. 1H, 13C, and 19F NMR chemical shifts of acetic acid and TFA molecules for acetic acid-water and TFA-water mixtures have indicated strong relationships between a structural change of the mixtures and the acid mole fraction. On the basis of both LAXS and NMR results, the structural changes of acetic acid-water and TFA-water mixtures with decreasing acid mole fraction and the effects of fluorination of the methyl group on the structure are discussed at the molecular level. PMID:17628099

  20. 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

  1. X-Ray Studies of Phase Transitions on Surfaces

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage

    1984-01-01

    The density variation across the surface from vapor to liquid in liquid crystal materials has been measured in the isotropic, nematic and smectic A phases by specular reflection of X rays with grazing angles from θc to θB (total reflection angle and Bragg angle for smectic A layering, respectively......) using synchroton X-rays in HASYLAB, Hamburg. Crystalline surface structures may be deduced from X-ray diffraction, utilizing the evanescent beam occuring for grazing angles less than θc to obtain surface sensitivity. Results from the reconstruction of Au(110) surface are reviewed....

  2. 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

  3. 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...

  4. 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...

  5. Laser-based X-ray and electron source for X-ray fluorescence studies

    CERN Document Server

    Brozas, F Valle; Roso, L; Conde, A Peralta

    2016-01-01

    In this work we present a modification to conventional X-rays fluorescence using electrons as excitation source, and compare it with the traditional X-ray excitation for the study of pigments. For this purpose we have constructed a laser-based source capable to produce X-rays as well as electrons. Because of the large penetration depth of X-rays, the collected fluorescence signal is a combination of several material layers of the artwork under study. However electrons are stopped in the first layers allowing therefore a more superficial analysis. We show that the combination of both excitation sources can provide extremely valuable information about the structure of the artwork.

  6. Hard X-Ray, Soft X-Ray, and EUV Studies of Solar Eruptions

    Science.gov (United States)

    Sterling, Alphonse C.; Wagner, William (Technical Monitor)

    2003-01-01

    Document study the hard X-ray (HXR), soft X-ray (SXR) ,EUV, and magnetic nature of solar eruptions, with the objective of elucidating the physics of the eruption process. In particular, it was examine the viability of two specific eruption mechanisms, detailed in our proposal. These mechanisms are the "breakout model", and the "tether cutting model". During the second year, it was a significant progress in the goals to Data Sets Utilized. In the publications during this second year of the grant period, the data was used from the E W Imaging Telescope (EIT) and the Michelson Doppler Imager (MDI) instruments on SOHO, and from the Soft X-ray Telescope (SXT), Hard X-ray Telescope (HXT), and the Bragg Crystal Spectrometer (BCS) on Yooh.

  7. High-pressure structural transformations of PbCrO{sub 4} up to 51.2 GPa: An angle-dispersive synchrotron X-ray diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Errandonea, D., E-mail: daniel.errandonea@uv.es [Departamento de Física Aplicada-ICMUV, MALTA Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia (Spain); Kumar, R.S. [High Pressure Science and Engineering Center, Department of Physics and Astronomy, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, Nevada 89154-4002 (United States)

    2014-12-15

    Highlights: • PbCrO{sub 4} was studied under high pressure up to 51 GPa using synchrotron powder XRD. • The occurrence of three phase transitions is reported. • The crystal structures of the high-pressure phases are assigned. • Axial and bulk compressibilities are determined. - Abstract: We report on high-pressure X-ray diffraction measurements up to 51.2 GPa in PbCrO{sub 4} at room temperature. Three high-pressure phases with structures different than the ambient-pressure monazite-type (P2{sub 1}/n) are reported. One phase transition was found at 3.8 GPa to an isomorphic structure to monazite. A second transition occurs at 11.1 GPa. After this transition, the coexistence of tetragonal (I4{sub 1}/a) and monoclinic (P2{sub 1}) structures is detected up to 21.1 GPa. Beyond this pressure and up to 51.2 GPa, only the high-pressure monoclinic phase is observed. Upon decompression all structural changes are reversible. Finally, the axial compressibilities for the different phases have been determined as well as the equations of state.

  8. 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...

  9. Multiple angle measurement and modeling of M-band x-ray fluxes from vacuum hohlraum

    Science.gov (United States)

    Guo, Liang; Li, Shanwei; Li, Zhichao; Jing, Longfei; Xie, Xufei; Jiang, Xiaohua; Yang, Dong; Du, Huabin; Hou, Lifei; Yang, Jiamin; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun; Hu, Guangyue; Zheng, Jian

    2016-09-01

    The energetics experiment of vacuum gold hohlraums is implemented on the Shenguang-II laser facility. The total and M-band x-ray fluxes from the laser entrance holes are measured by the flat response x-ray diodes which are set at multiple angles with respect to the axis of the hohlraums. The measured M-band fractions are from 5.72% to 7.71%, which present a specific angular distribution. Based on the fact that the M-band x-rays are mainly emitted from the under-dense high-temperature plasmas, a simplified model is developed to give a quantitative prediction of the intensity, temporal behavior, and angular distribution of the M-band x-ray flux. The results obtained with our model are in good agreement with the experimental data, showing that our model can be a useful tool for M-band x-ray investigation.

  10. 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.

  11. 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

  12. 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.

  13. 3-d chemical imaging using angle-scan nanotomography in a soft X-ray scanning transmission X-ray microscope

    International Nuclear Information System (INIS)

    Three-dimensional chemical mapping using angle scan nanotomography in a soft X-ray scanning transmission X-ray microscope (STXM) has been used to investigate the spatial distributions of a low density polyacrylate polyelectrolyte ionomer inside submicron sized polystyrene microspheres. Acquisition of tomograms at multiple photon energies provides true, quantifiable 3-d chemical sensitivity. Both pre-O 1s and C 1s results are shown. The study reveals aspects of the 3-d distribution of the polyelectrolyte that were inferred indirectly or had not been known prior to this study. The potential and challenges for extension of the technique to studies of other polymeric and to biological systems is discussed. (orig.)

  14. A double area detector system for simultaneous small and wide-angle X-ray scattering

    CERN Document Server

    Pokric, B; Ryan, A J; Fairclough, P; Dobson, B R; Derbyshire, G E; Helsby, W; Long, G; Moon, K

    2002-01-01

    A novel area detector has been designed for material science SR studies, capable of simultaneously collecting the diffraction data in two angular regimes. The detector for collecting wide-angle X-ray scattering (WAXS) data consists of four taper-coupled CCDs arranged as a 2x2 mosaic with a central aperture about 40 mm in diameter, so permitting the inclusion of a distant on-axis CCD detector for small-angle X-ray scattering (SAXS). The distance of the SAXS detector from the sample can be varied over the range 0.27 m to about 2 m. The overall aperture of WAXS detector is approximately 200x200 mm sup 2 allowing the measurement of the diffraction patterns from 5 deg. to 45 deg. with an average angular resolution of 0.05 deg. The parallax error for large angles is substantially reduced as the individual WAXS CCDs are tilted towards the specimen location. Both WAXS and SAXS diffraction data are simultaneously collected at 30 MB/s data rate, which is equivalent to 6 complete frames per second. Each pixel value is d...

  15. 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.

  16. 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.

  17. Spectroscopic studies of X-ray laser media

    International Nuclear Information System (INIS)

    velocity effects, τ0, the ratio of the spatial scalelength of the absorption coefficient to the Doppler decoupling length, R and the angle of the ray path to the normal to the planes. The net radiative bracket found to be related to the total optical depth, τ0tot, the R ratio and the optical depth at the emission point neglecting the velocity decoupling effects, τr. Results of an experiment carried out to generate wave-guides for x-ray lasers to minimise the transverse refraction losses are presented. Five beams of the VULCAN laser were used to illuminate 40 mm long Ge targets leading to well saturated Ge XRL outputs at 196A. Simulated x-ray laser output has been fitted to experimentally measured outputs to find the actual incident energy needed to allow for unmodelled energy losses in the absorption process. The input irradiances to the EHYBRID fluid and atomic physics code have been reduced by a factor F from the experimental irradiance until the code predictions and experimental results agree. After removing a previously utilised reduction of the monopole excitation rate in Ne-like ions, we found that a factor F = 0.7 gives simulated x-ray laser output energy for Ne-like Ge at 196 A in agreement with experiment for 75 ps irradiation. The uniformity of the line foci created with the five overlapping beams has been studied by simulating cross-slit camera images using EHYBRID code. The x-ray laser output was incident onto a short (∼ 4 mm) length of plasma irradiated to produce a density 'well' along the line focus length which acts a one-dimensional wave-guide. Analysing the XRL outputs from 40 mm long Ge targets with and without using the wave-guide showed that there was no amplification of the x-ray laser passing through the wave-guide. Some waveguiding without gain may have been achieved as the x-ray laser beam divergence was reduced after passing through the waveguiding plasma. Results from an experiment on travelling wave pumping of the Ne-like Ge x-ray lasers in

  18. Design studies for ITER x-ray diagnostics

    International Nuclear Information System (INIS)

    Concepts for adapting conventional tokamak x-ray diagnostics to the harsh radiation environment of ITER include use of grazing-incidence (GI) x-ray mirrors or man-made Bragg multilayer (ML) elements to remove the x-ray beam from the neutron beam, or use of bundles of glass-capillary x-ray ''light pipes'' embedded in radiation shields to reduce the neutron/gamma-ray fluxes onto the detectors while maintaining usable x-ray throughput. The x-ray optical element with the broadest bandwidth and highest throughput, the GI mirror, can provide adequate lateral deflection (10 cm for a deflected-path length of 8 m) at x-ray energies up to 12, 22, or 30 keV for one, two, or three deflections, respectively. This element can be used with the broad band, high intensity x-ray imaging system (XIS), the pulseheight analysis (PHA) survey spectrometer, or the high resolution Johann x-ray crystal spectrometer (XCS), which is used for ion-temperature measurement. The ML mirrors can isolate the detector from the neutron beam with a single deflection for energies up to 50 keV, but have much narrower bandwidth and lower x-ray power throughput than do the GI mirrors; they are unsuitable for use with the XIS or PHA, but they could be used with the XCS; in particular, these deflectors could be used between ITER and the biological shield to avoid direct plasma neutron streaming through the biological shield. Graded-d ML mirrors have good reflectivity from 20 to 70 keV, but still at grazing angles (<3 mrad). The efficiency at 70 keV for double reflection (10 percent), as required for adequate separation of the x-ray and neutron beams, is high enough for PHA requirements, but not for the XIS. Further optimization may be possible

  19. Microfibril angle variability in Masson Pine (Pinus massoniana Lamb.) using X-ray diffraction

    Institute of Scientific and Technical Information of China (English)

    Zhang Bo; Fei Ben-hua; Yu Yan; Zhao Rong-jun

    2007-01-01

    The microfibril angle of fiber walls is an ultra-microscopic feature affecting the performance of wood products. It is therefore essential to get more definitive information to improve selection and utilization. X-ray diffraction is a rapid method for measuring micro fibril angles. In this paper, the variability of microfibril angle in plantation-grown Masson pine was investigated by peak-fitting method. This method was compared with the traditional hand-drawn method, 40% peak height method and half peak height method. X-ray diffraction measurements indicated that the microfibril angle changed as a function of the position in the tree.The mean micro fibril angle decreased more gradually as the distance increased from the pith and reached the same level in mature wood. The microfibril angle also seemed to decrease clearly from the base upward. Differences of angle-intensity curves between heartwood and sapwood were also examined.

  20. Optimization of the x-ray monitoring angle for creating a correlation model between internal and external respiratory signals

    Energy Technology Data Exchange (ETDEWEB)

    Akimoto, Mami; Nakamura, Mitsuhiro; Mukumoto, Nobutaka; Yamada, Masahiro; Ueki, Nami; Matsuo, Yukinori; Sawada, Akira; Mizowaki, Takashi; Kokubo, Masaki; Hiraoka, Masahiro [Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto 606-8507 (Japan); Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan and Department of Radiological Technology, Faculty of Medical Science, Kyoto College of Medical Science, Nantan, Kyoto 622-0041 (Japan); Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto 606-8507 (Japan); Department of Radiation Oncology, Kobe City Medical Center General Hospital, Kobe, Hyogo 650-0047, Japan and Division of Radiation Oncology, Institute of Biomedical Research and Innovation, Kobe, Hyogo 650-0047 (Japan); Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto 606-8507 (Japan)

    2012-10-15

    Purpose: To perform dynamic tumor tracking irradiation with the Vero4DRT (MHI-TM2000), a correlation model [four dimensional (4D) model] between the displacement of infrared markers on the abdominal wall and the three-dimensional position of a tumor indicated by a minimum of three implanted gold markers is required. However, the gold markers cannot be detected successfully on fluoroscopic images under the following situations: (1) overlapping of the gold markers; and (2) a low intensity ratio of the gold marker to its surroundings. In the present study, the authors proposed a method to readily determine the optimal x-ray monitoring angle for creating a 4D model utilizing computed tomography (CT) images. Methods: The Vero4DRT mounting two orthogonal kV x-ray imaging subsystems can separately rotate the gantry along an O-shaped guide-lane and the O-ring along its vertical axis. The optimal x-ray monitoring angle was determined on CT images by minimizing the root-sum-square of water equivalent path lengths (WEPLs) on the orthogonal lines passing all of the gold markers while rotating the O-ring and the gantry. The x-ray monitoring angles at which the distances between the gold markers were within 5 mm at the isocenter level were excluded to prevent false detection of the gold markers in consideration of respiratory motions. First, the relationship between the WEPLs (unit: mm) and the intensity ratios of the gold markers was examined to assess the validity of our proposed method. Second, our proposed method was applied to the 4D-CT images at the end-expiration phase for 11 lung cancer patients who had four to five gold markers. To prove the necessity of the x-ray monitoring angle optimization, the intensity ratios of the least visible markers (minimum intensity ratios) that were estimated from the WEPLs were compared under the following conditions: the optimal x-ray monitoring angle and the angles used for setup verification. Additionally, the intra- and

  1. Optimization of the x-ray monitoring angle for creating a correlation model between internal and external respiratory signals

    International Nuclear Information System (INIS)

    Purpose: To perform dynamic tumor tracking irradiation with the Vero4DRT (MHI-TM2000), a correlation model [four dimensional (4D) model] between the displacement of infrared markers on the abdominal wall and the three-dimensional position of a tumor indicated by a minimum of three implanted gold markers is required. However, the gold markers cannot be detected successfully on fluoroscopic images under the following situations: (1) overlapping of the gold markers; and (2) a low intensity ratio of the gold marker to its surroundings. In the present study, the authors proposed a method to readily determine the optimal x-ray monitoring angle for creating a 4D model utilizing computed tomography (CT) images. Methods: The Vero4DRT mounting two orthogonal kV x-ray imaging subsystems can separately rotate the gantry along an O-shaped guide-lane and the O-ring along its vertical axis. The optimal x-ray monitoring angle was determined on CT images by minimizing the root-sum-square of water equivalent path lengths (WEPLs) on the orthogonal lines passing all of the gold markers while rotating the O-ring and the gantry. The x-ray monitoring angles at which the distances between the gold markers were within 5 mm at the isocenter level were excluded to prevent false detection of the gold markers in consideration of respiratory motions. First, the relationship between the WEPLs (unit: mm) and the intensity ratios of the gold markers was examined to assess the validity of our proposed method. Second, our proposed method was applied to the 4D-CT images at the end-expiration phase for 11 lung cancer patients who had four to five gold markers. To prove the necessity of the x-ray monitoring angle optimization, the intensity ratios of the least visible markers (minimum intensity ratios) that were estimated from the WEPLs were compared under the following conditions: the optimal x-ray monitoring angle and the angles used for setup verification. Additionally, the intra- and

  2. A filter based analyzer for studies of X-ray Raman scattering

    CERN Document Server

    Seidler, G T

    2001-01-01

    Non-resonant X-ray Raman scattering (XRS) with hard X-rays holds the potential for measuring local structure and local electronic properties around low-Z atoms in environments where traditional soft X-ray techniques are inapplicable. However, the small cross-section for XRS requires that experiments must simultaneously achieve high detection efficiency, large collection solid angles, and good energy resolution. We report here that a simple X-ray analyzer consisting of an absorber and a point-focusing spatial filter can be used to study some X-ray Raman near-edge features. This apparatus has greater than 10% detection efficiency, has an energy resolution of 8 eV, and can be readily extended to collection angles of more than 1 sr. We present preliminary measurements of the XRS from the nitrogen 1 s shell in pyrolitic boron nitride.

  3. Dark field X-ray microscopy for studies of recrystallization

    DEFF Research Database (Denmark)

    Ahl, Sonja Rosenlund; Simons, Hugh; Jakobsen, Anders Clemen;

    2015-01-01

    We present the recently developed technique of Dark Field X-Ray Microscopy that utilizes the diffraction of hard X-rays from individual grains or subgrains at the (sub)micrometre- scale embedded within mm-sized samples. By magnifying the diffracted signal, 3D mapping of orientations and strains...... external influences. The capabilities of Dark Field X- Ray Microscopy are illustrated by examples from an ongoing study of recrystallization of 50% cold-rolled Al1050 specimens....

  4. 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

  5. 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.)

  6. Fabrication of large-area and low mass critical-angle x-ray transmission gratings

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alex R.; Guan, Dong; Schattenburg, Mark L.

    2014-07-01

    Soft x-ray spectroscopy of celestial sources with high resolving power R = E/ΔE and large collecting area addresses important science listed in the Astro2010 Decadal Survey New Worlds New Horizons, such as the growth of the large scale structure of the universe and its interaction with active galactic nuclei, the kinematics of galactic outflows, as well as coronal emission from stars and other topics. Numerous studies have shown that a transmission grating spectrometer based on lightweight critical-angle transmission (CAT) gratings can deliver R = 3000-5000 and large collecting area with high efficiency and minimal resource requirements, providing spectroscopic figures of merit at least an order of magnitude better than grating spectrometers on Chandra and XMM-Newton, as well as future calorimeter-based missions. The recently developed CAT gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Their working principle based on blazing through reflection off the smooth, ultra-high aspect ratio grating bar sidewalls has previously been demonstrated on small samples with x rays. For larger gratings (area greater than 1 inch square) we developed a fabrication process for grating membranes with a hierarchy of integrated low-obscuration supports. The fabrication involves a combination of advanced lithography and highly anisotropic dry and wet etching techniques. We report on the latest fabrication results of free-standing, large-area CAT gratings with polished sidewalls and preliminary x-ray tests.

  7. Image reconstruction from limited angle projections collected by multi-source interior x-ray imaging systems

    OpenAIRE

    Liu, Baodong; Wang, Ge; Ritman, Erik L.; Cao, Guohua; Lu, Jianping; Zhou, Otto; Zeng, Li; Yu, Hengyong

    2011-01-01

    A multi-source x-ray interior imaging system with limited angle scanning is investigated to study the possibility of building an ultra-fast micro-CT for dynamic small animal imaging. And two methods are employed to perform interior reconstruction from a limited number of projections collected by the multi-source interior x-ray system. The first is total variation minimization with the steepest descent search (TVM-SD) and the second is total difference minimization with soft-threshold filterin...

  8. X-ray and optical studies of dense plasmas

    Science.gov (United States)

    Ellwi, Samir Shakir

    X-ray and optical investigations of dense plasmas and x- ray sources for laser-plasma studies are presented in this thesis. Short pulse laser interaction with solids is reviewed. The transport of laser energy into the bulk of the target by electron thermal conduction, radiation and shock waves is described. X-ray characterisation of different types of plasma are presented. The first experiment deals with the generation of a plasma cathode x-ray source. The experimental results are compared with a simulation made using a simple self consistent model. The x-ray source size depends upon the cone angle of the tip of the anode. A wide range of experimental data for different parameters (anode-cathode separation, anode positive voltages, anode material, cathode material and different laser energies) is collected and analysed. In chapter 5 the equation of state of gold is studied using the shock wave reflection method. Experimental measurements are done for the direct and indirect drives. The experimental data are compared to the SESAME tabular data. Indirect drive is found to give a more accurate measurement compared to direct drive using the Phase Zone Plate (PZP) method technique. Preheating effects in laser driven shock waves is presented in chapter 6. We used two different diagnostics: the colour temperature measurements deduced by recording the target rear side emissivity in two spectral bands and the target rear side reflectivity measurements. We use the MULTI hydrodynamic code to measure the temperature of the preheat and in coupling with the Fresnel reflectivity model in order to compare the theoretical calculations to the experimental observations. Qualitative results of energy transport by hot fast electrons in solid cold and compressed plastic are presented in chapter 7. K-alpha emission from chlorine fluor buried layers is used to measure the fast electron transport. These data are collected from time integrated spectrometers using k-alpha spectroscopy of the

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. X-ray Studies of Flaring Plasma

    Indian Academy of Sciences (India)

    B. Sylwester; J. Sylwester; K. J. H. Phillips

    2008-03-01

    We present some methods of X-ray data analysis employed in our laboratory for deducing the physical parameters of flaring plasma. For example, we have used a flare well observed with Polish instrument RESIK aboard Russian CORONAS-F satellite. Based on a careful instrument calibration, the absolute fluxes in a number of individual spectral lines have been obtained. The analysis of these lines allows us to follow the evolution of important thermodynamic parameters characterizing the emitting plasma throughout this flare evolution.

  14. Amorphous silica studied by high energy x-ray diffraction

    DEFF Research Database (Denmark)

    Poulsen, H.F.; Neuefeind, J.; Neumann, H.B.;

    1995-01-01

    The use of hard X-rays (60-300 keV) for diffraction studies of disordered materials has several advantages: higher resolution in direct space, smaller correction terms, removal of truncation effects, the possibility for operating in extreme environments and for direct comparison between X-ray...

  15. High-resolution X-ray diffraction studies of multilayers

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Hornstrup, Allan; Schnopper, H. W.

    1988-01-01

    High-resolution X-ray diffraction studies of the perfection of state-of-the-art multilayers are presented. Data were obtained using a triple-axis perfect-crystal X-ray diffractometer. Measurements reveal large-scale figure errors in the substrate. A high-resolution triple-axis set up is required...

  16. Planetary X-ray studies: past, present and future

    Science.gov (United States)

    Branduardi-Raymont, Graziella

    2016-07-01

    Our solar system is a fascinating physics laboratory and X-ray observations are now firmly established as a powerful diagnostic tool of the multiple processes taking place in it. The science that X-rays reveal encompasses solar, space plasma and planetary physics, and the response of bodies in the solar system to the impact of the Sun's activity. This talk will review what we know from past observations and what we expect to learn in the short, medium and long term. Observations with Chandra and XMM-Newton have demonstrated that the origin of Jupiter's bright soft X-ray aurorae lies in the Charge eXchange (CX) process, likely to involve the interaction with atmospheric neutrals of local magnetospheric ions, as well as those carried in the solar wind. At higher energies electron bremsstrahlung is thought to be the X-ray emitting mechanism, while the whole planetary disk acts as a mirror for the solar X-ray flux via Thomson and fluorescent scattering. This 'X-ray mirror' phenomenon is all that is observed from Saturn's disk, which otherwise lacks X-ray auroral features. The Earth's X-ray aurora is bright and variable and mostly due to electron bremsstrahlung and line emission from atmospheric species. Un-magnetised planets, Venus and Mars, do not show X-ray aurorae but display the interesting combination of mirroring the solar X-ray flux and producing X-rays by Solar Wind Charge eXchange (SWCX) in their exospheres. These processes respond to different solar stimulation (photons and solar wind plasma respectively) hence their relative contributions are seen to vary according to the Sun's output. Present and future of planetary X-ray studies are very bright. We are preparing for the arrival of the Juno mission at Jupiter this summer and for coordinated observations with Chandra and XMM-Newton on the approach and later during Juno's orbital phase. These will allow direct correlation of the local plasma conditions with the X-ray emissions and the establishment of the

  17. Improved signal-to-noise ratio for non-perpendicular detection angles in x-ray fluorescence computed tomography (XFCT)

    Science.gov (United States)

    Sjölin, Martin; Danielsson, Mats

    2014-11-01

    The standard imaging setup in x-ray fluorescence computed tomography detects the fluorescence emission at a right angle with respect to the axis of the excitation beam. In this paper we have studied how the detection angle affects the signal-to-noise ratio (S/N), which is a major factor influencing the low-contrast sensitivity of the imaging system. This is done for an imaging setup using a collimated detector and a pencil beam of excitation x-rays. An ideal detection process is simulated for a generalized imaging case with gold/platinum tracers and experimental measurements are performed using a diagnostic x-ray tube. For monochromatic excitation, the results indicate that order-of-magnitude improvements of the S/N can be achieved by optimizing the detection angle. The maximal S/N, when exciting with an energy just above the K-edge, is achieved for large detection angles, i.e. with the detector close to the source. The improvements also transfer to polychromatic excitation sources and the experimental results show up to four-fold improvements of the S/N when changing the detection angle from 90° to 150°. Also, the changes of the S/N behavior when switching the fluorescent tracer is briefly demonstrated. These results suggest that the choice of detection angle should be taken seriously in the design of future XFCT imaging systems.

  18. Influence of angle's ranges for recording an X-ray fluorescence hologram on reconstructed atomic images

    Institute of Scientific and Technical Information of China (English)

    XIE Hong-Lan; CHEN Jian-Wen; GAO Hong-Yi; ZHU Hua-Feng; LI Ru-Xin; XU Zhi-Zhan

    2004-01-01

    X-ray fluorescence holography (XFH) is a novel method for three-dimensional (3D) imaging of atomic structure. Theoretically, in an XFH experiment, one has to measure the fluorescence energy on a spherical surface to get well-resolved 3D images of atoms. But in practice, the experimental system arrangement does not allow the measurement of the fluorescent intensity oscillations in the full sphere. The holographic information losses because of the limited sampling range (less than 4π) will directly result in defective reconstructed atomic images. In this work, the atomic image of a Fe single crystal (001) was reconstructed by numerically simulating X-ray fluorescence holograms of the crystal at different recording angle's ranges and step lengths. Influences of the ranges of azimuth angles and polar angles and the step length of polar angles on the reconstructed atomic images were discussed.

  19. 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.

  20. Microfocus wide-angle X-ray scattering of polymers crystallized in a fast scanning chip calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Drongelen, Martin van [Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Meijer-Vissers, Tamara [Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven (Netherlands); Cavallo, Dario, E-mail: d.cavallo1@tue.nl [Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Portale, Giuseppe [ESRF, Dubble CRG, Netherlands Organization of Scientific Research (NWO), 38043 Grenoble (France); Poel, Geert Vanden [DSM Resolve, Urmonderbaan 22, 6167 RD Geleen (Netherlands); Androsch, René, E-mail: rene.androsch@iw.uni-halle.de [Martin-Luther-University Halle-Wittenberg, Center of Engineering Sciences, 06099 Halle/Saale (Germany)

    2013-07-10

    Graphical abstract: - Highlights: • Micro-focused synchrotron radiation was used for WAXS analysis of FSC samples. • FSC polymer crystallization experiments were completed by in situ X-ray structure analysis. • The supercooling-controlled polymorphism of iPP and PA 6 has been confirmed. - Abstract: Microfocus wide-angle X-ray scattering (WAXS) has been applied for analysis of the polymorphism of isotactic polypropylene and polyamide 6 prepared in a fast scanning chip calorimeter (FSC). Samples with a typical mass of few hundred nanograms, and lateral dimension and thickness of about 100 μm and 20 μm, respectively, were exposed to a defined thermal history in the FSC and subsequently analyzed regarding the X-ray structure at ambient temperature using an intense synchrotron microfocused X-ray beam. The relaxed melt of isotactic polypropylene was cooled at rates of 40 K s{sup −1} and 200 K s{sup −1} which allowed formation of α-crystals or mesophase, respectively. Polyamide 6 was isothermally crystallized at 95 °C and 180 °C which led to formation of γ-mesophase and α-crystals, respectively. This study demonstrated, for the first time, that FSC polymer crystallization experiments could be completed and expanded by subsequent in situ structure analysis by X-ray scattering.

  1. A flexible setup for angle-resolved X-ray fluorescence spectrometry with laboratory sources.

    Science.gov (United States)

    Spanier, M; Herzog, C; Grötzsch, D; Kramer, F; Mantouvalou, I; Lubeck, J; Weser, J; Streeck, C; Malzer, W; Beckhoff, B; Kanngießer, B

    2016-03-01

    X-ray fluorescence (XRF) analysis is one of the standard tools for the analysis of stratified materials and is widely applied for the investigation of electronics and coatings. The composition and thickness of the layers can be determined quantitatively and non-destructively. Recent work showed that these capabilities can be extended towards retrieving stratigraphic information like concentration depth profiles using angle-resolved XRF (ARXRF). This paper introduces an experimental sample chamber which was developed as a multi-purpose tool enabling different measurement geometries suited for transmission measurements, conventional XRF, ARXRF, etc. The chamber was specifically designed for attaching all kinds of laboratory X-ray sources for the soft and hard X-ray ranges as well as various detection systems. In detail, a setup for ARXRF using an X-ray tube with a polycapillary X-ray lens as source is presented. For such a type of setup, both the spectral and lateral characterizations of the radiation field are crucial for quantitative ARXRF measurements. The characterization is validated with the help of a stratified validation sample. PMID:27036820

  2. X-ray spectral determination by detection of radiation scattered at different angles

    International Nuclear Information System (INIS)

    A precise knowledge of the spectral content of an X-ray beam is of fundamental importance in areas such as X-ray fluorescence analysis by absolute methods, radiodiagnosis, radiotherapy, computed tomography, etc. A simple practical method was developed to determine X-ray spectra emitted by X-ray tubes. It is based on the scattering of the beam on a solid target and detection of this radiation at different angles. This methodology can easily be adapted to the successive attenuation of the beam procedure. Numerical parameter values of a proposed analytical function for the energy spectrum are found measuring the radiation intensity with a suitable detector (ionization chamber or plastic scintillation detector) and equating it with the convolution integral of the proposed spectrum with the incoherent scattering function. This procedure of spectra determination is enclosed in the same group of those generically referred as successive modifications of the irradiation set up used in absolute methods of X-ray fluorescence analysis. (Author)

  3. A flexible setup for angle-resolved X-ray fluorescence spectrometry with laboratory sources

    Science.gov (United States)

    Spanier, M.; Herzog, C.; Grötzsch, D.; Kramer, F.; Mantouvalou, I.; Lubeck, J.; Weser, J.; Streeck, C.; Malzer, W.; Beckhoff, B.; Kanngießer, B.

    2016-03-01

    X-ray fluorescence (XRF) analysis is one of the standard tools for the analysis of stratified materials and is widely applied for the investigation of electronics and coatings. The composition and thickness of the layers can be determined quantitatively and non-destructively. Recent work showed that these capabilities can be extended towards retrieving stratigraphic information like concentration depth profiles using angle-resolved XRF (ARXRF). This paper introduces an experimental sample chamber which was developed as a multi-purpose tool enabling different measurement geometries suited for transmission measurements, conventional XRF, ARXRF, etc. The chamber was specifically designed for attaching all kinds of laboratory X-ray sources for the soft and hard X-ray ranges as well as various detection systems. In detail, a setup for ARXRF using an X-ray tube with a polycapillary X-ray lens as source is presented. For such a type of setup, both the spectral and lateral characterizations of the radiation field are crucial for quantitative ARXRF measurements. The characterization is validated with the help of a stratified validation sample.

  4. 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.

  5. 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

  6. X-ray structures and computational studies of several cathinones

    Science.gov (United States)

    Nycz, Jacek E.; Malecki, Grzegorz; Zawiazalec, Marcin; Pazdziorek, Tadeusz

    2011-09-01

    2-(Ethylamino)-1-(4-methylphenyl)propan-1-one (shortly named 4-MEC) ( 1a), 1-(1,3-benzodioxol-5-yl)-2-(methylamino)propan-1-one (shortly named methylone or 3,4-methylenedioxymethcathinone) ( 1b), 1-(3,4-dimethylphenyl)-2-(methylamino)propan-1-one ( 1c), 2-methylamino-1-(4-methylphenyl)propan-1-one (shortly named mephedrone; 4-MMC or 4-methylmethcathinone) ( 1d) and 2-(methylamino)-1-phenylbutan-1-one (shortly named buphedrone) ( 1e) and their aminium salts ( 2a-e), are examples of cathinones which were characterized by FTIR, UV-Vis, multinuclear NMR spectroscopy. By single crystal X-ray diffraction method structures of 2a, 2b, 2c and 2d were determined. NMR solution spectra showed readily diagnostic H-1 and C-13 signals from methyl, ethyl, N-methyl or N-ethyl groups. The diastereotopic methylene protons of 1a appear as an ABX 3, and 1e and 2e appear as an ABMX 3 system. The geometries of the studied compounds were optimized in singlet states using the density functional theory (DFT) method with B3LYP functional. Electronic spectra were calculated by TDDFT method. In general, the predicted bond lengths and angles are in good agreement with the values based on the X-ray crystal structure data.

  7. 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...

  8. Synchrotron X-ray studies of liquid-vapor interfaces

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage

    1986-01-01

    The density profile ρ(z) across a liquid-vapor interface may be determined by the reflectivity R(θ) of X-rays at grazing angle incidence θ. The relation between R(θ) and ρ(z) is discussed, and experimental examples illustrating thermal roughness of simple liquids and smectic layering of liquid...

  9. Critical-angle transmission grating spectrometer for high-resolution soft x-ray spectroscopy on the International X-ray Observatory

    Science.gov (United States)

    Heilmann, Ralf K.; Davis, John E.; Dewey, Daniel; Bautz, Mark W.; Foster, Rick; Bruccoleri, Alex; Mukherjee, Pran; Robinson, David; Huenemoerder, David P.; Marshall, Herman L.; Schattenburg, Mark L.; Schulz, Norbert S.; Guo, L. Jay; Kaplan, Alex F.; Schweikart, Russell B.

    2010-07-01

    High-resolution spectroscopy at energies below 1 keV covers the lines of C, N, O, Ne and Fe ions, and is central to studies of the Interstellar Medium, the Warm Hot Intergalactic Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, etc. The large collecting area, long focal length, and 5 arcsecond half power diameter telescope point-spread function of the International X-ray Observatory will present unprecedented opportunity for a grating spectrometer to address these areas at the forefront of astronomy and astrophysics. We present the current status of a transmission grating spectrometer based on recently developed high-efficiency critical-angle transmission (CAT) gratings that combine the traditional advantages of blazed reflection and transmission gratings. The optical design places light-weight grating arrays close to the telescope mirrors, which maximizes dispersion distance and thus spectral resolution and minimizes demands on mirror performance. It merges features from the Chandra High Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer, and provides resolving power R = E/ΔE = 3000 - 5000 (full width half max) and effective area >1000 cm2 in the soft x-ray band. We discuss recent results on ray-tracing and optimization of the optical design, instrument configuration studies, and grating fabrication.

  10. 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.

  11. Spectroscopic Studies of X-Ray Binary Pulsars

    Indian Academy of Sciences (India)

    F. Nagase

    2002-03-01

    Several new features of X-ray binary pulsars are revealed from recent observations with ASCA, RXTE, BeppoSAX and other X-ray observatories. Among these, I will review in this paper some recent progress in spectroscopic studies of accreting X-ray pulsars in binary systems (XBPs). First, I will discuss soft excess features observed in the energy spectra of XBPs and propose that it is a common feature for various subclasses of XBPs. Next I will present some recent results of high resolution spectroscopy with ASCA and Chandra.

  12. 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.

  13. Fabrication update on critical-angle transmission gratings for soft x-ray grating spectrometers

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alex; Mukherjee, Pran; Yam, Jonathan; Schattenburg, Mark L.

    2011-09-01

    Diffraction grating-based, wavelength dispersive high-resolution soft x-ray spectroscopy of celestial sources promises to reveal crucial data for the study of the Warm-Hot Intergalactic Medium, the Interstellar Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, and other areas of interest to the astrophysics community. Our recently developed critical-angle transmission (CAT) gratings combine the advantages of the Chandra high and medium energy transmission gratings (low mass, high tolerance of misalignments and figure errors, polarization insensitivity) with those of blazed reflection gratings (high broad band diffraction efficiency, high resolution through use of higher diffraction orders) such as the ones on XMM-Newton. Extensive instrument and system configuration studies have shown that a CAT grating-based spectrometer is an outstanding instrument capable of delivering resolving power on the order of 5,000 and high effective area, even with a telescope point-spread function on the order of many arc-seconds. We have fabricated freestanding, ultra-high aspect-ratio CAT grating bars from silicon-on-insulator wafers using both wet and dry etch processes. The 200 nm-period grating bars are supported by an integrated Level 1 support mesh, and a coarser external Level 2 support mesh. The resulting grating membrane is mounted to a frame, resulting in a grating facet. Many such facets comprise a grating array that provides light-weight coverage of large-area telescope apertures. Here we present fabrication results on the integration of CAT gratings and the different high-throughput support mesh levels and on membrane-frame bonding. We also summarize recent x-ray data analysis of 3 and 6 micron deep wet-etched CAT grating prototypes.

  14. 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.

  15. Optimal main pulse angle for different preplasma conditions in transient collisionally pumped x-ray lasers.

    Science.gov (United States)

    Ursescu, Daniel; Zielbauer, Bernhard; Kuehl, Thomas; Neumayer, Paul; Pert, Geoff

    2007-04-01

    The effects of the incidence angle of the main pump (MP) pulse in non-normal pumping geometry and the influence of the MP duration are investigated experimentally and theoretically for a transient collisionally pumped (TCE) x-ray laser in Ni-like Zr at 45 degrees and 72 degrees incidence angle on the target. The way they transfer to the x-ray laser output depends on the preplasma conditions, most notably on the average ionization distribution at the arrival of the MP. Moreover, contrary to previous grazing incidence pumping results, it is found that the shortest attainable MP maximizes the output. Modeling of the experimental results is performed with EHYBRID code. The results are important for scaling high repetition-rate non-normal incidence pumped lasers to sub- 10nm wavelengths.

  16. 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.

  17. Synchrotron x-ray diffraction study of liquid surfaces

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Pershan, P.S.

    1983-01-01

    A spectrometer for X-ray diffraction and refraction studies of horizontal, free surfaces of liquids is described. As an illustration smetic-A layering at the surface of a liquid crystal is presented.......A spectrometer for X-ray diffraction and refraction studies of horizontal, free surfaces of liquids is described. As an illustration smetic-A layering at the surface of a liquid crystal is presented....

  18. 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...

  19. 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

  20. 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.

  1. Metal ion controlled self-assembly of a chemically reengineered protein drug studied by small-angle X-ray scattering

    DEFF Research Database (Denmark)

    Jesper, Nygaard; Munch, Henrik K.; Thulstrup, Peter W.;

    2012-01-01

    Precise control of the oligomeric state of proteins is of central importance for biological function and for the properties of biopharmaceutical drugs. Here, the self-assembly of 2,2′-bipyridine conjugated monomeric insulin analogues, induced through coordination to divalent metal ions, was studied....... This protein drug system was designed to form non-native homo-oligomers through selective coordination of two divalent metal ions, Fe(II) and Zn(II), respectively. The insulin type chosen for this study is a variant designed for a reduced tendency toward native dimer formation at physiological concentrations...

  2. Langmuir-Blodgett mono- and multilayers of preformed poly(octadecyl methacrylate)s, 2. Structural studies by IR spectroscopy and small-angle X-ray scattering

    NARCIS (Netherlands)

    Arndt, Thomas; Schouten, Arend Jan; Schmidt, Günther F.; Wegner, Gerhard

    1991-01-01

    Langmuir-Blodgett (LB) mono- and multilayers of preformed atactic and isotactic poly(octadecyl methacrylate)s were studied on gold surfaces and silicon wafers. The average orientation of the carbonyl bond of the ester group was found to be about 50° with respect to the normal to the substrate, and t

  3. High-resolution soft-X-ray beamline ADRESS at Swiss Light Source for resonant inelastic X-ray scattering and angle-resolved photoelectron spectroscopies

    OpenAIRE

    Strocov, V. N.; Schmitt, T; U. Flechsig; Schmidt, T.; Imhof, A; Q. Chen; J. Raabe; Betemps, R.; Zimoch, D.; Krempasky, J.; A. Piazzalunga; X Wang; Grioni, M.; Patthey, L.

    2009-01-01

    We describe the concepts and technical realization of the high-resolution soft-X-ray beamline ADRESS operating in the energy range from 300 to 1600 eV and intended for Resonant Inelastic X-ray Scattering (RIXS) and Angle-Resolved Photoelectron Spectroscopy (ARPES). The photon source is an undulator of novel fixed-gap design where longitudinal movement of permanent magnetic arrays controls not only the light polarization (including circular and 0-180 deg rotatable linear polarizations) but als...

  4. High-resolution soft X-ray beamline ADRESS at the Swiss Light Source for resonant inelastic X-ray scattering and angle-resolved photoelectron spectroscopies

    OpenAIRE

    Strocov, V. N.; Schmitt, T; U. Flechsig; Schmidt, T.; Imhof, A; Q. Chen; J. Raabe; Betemps, R.; Zimoch, D.; Krempasky, J.; X Wang; Grioni, M.; A. Piazzalunga; Patthey, L.

    2010-01-01

    The concepts and technical realisation of the high-resolution soft X-ray beamline ADRESS operating in the energy range from 300 to 1600 eV and intended for resonant inelastic X-ray scattering (RIXS) and angle-resolved photoelectron spectroscopy (ARPES) are described. The photon source is an undulator of novel fixed-gap design where longitudinal movement of permanent magnetic arrays controls not only the light polarization (including circular and 0–180° rotatable linear polarizations) but also...

  5. Small Angle X-Ray Scattering Studies of Mitochondrial Glutaminase C Reveal Extended Flexible Regions, and Link Oligomeric State with Enzyme Activity

    DEFF Research Database (Denmark)

    Møller, M.; Nielsen, Søren Skou; Ramachandran, Siddharth;

    2013-01-01

    Glutaminase C is a key metabolic enzyme, which is unregulated in many cancer systems and believed to play a central role in the Warburg effect, whereby cancer cells undergo changes to an altered metabolic profile. A long-standing hypothesis links enzymatic activity to the protein oligomeric state......, hence the study of the solution behavior in general and the oligomer state in particular of glutaminase C is important for the understanding of the mechanism of protein activation and inhibition. In this report, this is extensively investigated in correlation to enzyme concentration or phosphate level...... state and investigates the C-terminal influence on the enzyme solution behavior. Our data enable SAXS-based rigid body modeling of the full-length tetramer states, thereby presenting the first ever experimentally derived structural model of mitochondrial glutaminase C including the N- and C...

  6. Structure of wild type and mutant F508del CFTR: A small-angle X-ray scattering study of the protein-detergent complexes.

    Science.gov (United States)

    Pollock, Naomi L; Satriano, Letizia; Zegarra-Moran, Olga; Ford, Robert C; Moran, Oscar

    2016-04-01

    CFTR is an anionic channel expressed in epithelia whose mutations cause cystic fibrosis. Wild (WT) and mutated (F508del) types were over-expressed in yeast, solubilised in the detergent LPG-14 and purified. The detergent-CFTR complexes were studied by SAXS techniques using a solvent of variable density. The final result of the study is the numerical value of a set of parameters: molecular mass, volume and radius of gyration, average electron density and second moment of the electron density fluctuations inside the particles. It is also shown that in the complex the centres of gravity of CFTR and of the detergent are displaced relative to each other. The analysis of these parameters led to the determination of the size and shape of the volumes occupied by protein and by detergent in the complex. WT-CFTR to be an elongated molecule (maximum diameter ∼12.4nm) which spans a flat detergent micelle. The distance distribution function, P(r) confirms that the WT-CFTR is elongated and with an inhomogeneous electronic density. The F508del-CFTR molecule is also elongated (maximum diameter ∼13.2nm), but the associated detergent micelle hides a larger surface, plausibly related to an increased exposure of hydrophobic portions of the mutated protein. The corresponding P(r) is consistent with the presence of well defined domains, probably linked by flexible regions. These differences suggest that the full-length mutant F508del-CFTR has a detectably different conformation, in contrast to the minor differences observed for the isolated F508-containing domain. We interpret the data in terms of an incomplete post-translational assembly of the protein domains.

  7. Structure of wild type and mutant F508del CFTR: A small-angle X-ray scattering study of the protein-detergent complexes.

    Science.gov (United States)

    Pollock, Naomi L; Satriano, Letizia; Zegarra-Moran, Olga; Ford, Robert C; Moran, Oscar

    2016-04-01

    CFTR is an anionic channel expressed in epithelia whose mutations cause cystic fibrosis. Wild (WT) and mutated (F508del) types were over-expressed in yeast, solubilised in the detergent LPG-14 and purified. The detergent-CFTR complexes were studied by SAXS techniques using a solvent of variable density. The final result of the study is the numerical value of a set of parameters: molecular mass, volume and radius of gyration, average electron density and second moment of the electron density fluctuations inside the particles. It is also shown that in the complex the centres of gravity of CFTR and of the detergent are displaced relative to each other. The analysis of these parameters led to the determination of the size and shape of the volumes occupied by protein and by detergent in the complex. WT-CFTR to be an elongated molecule (maximum diameter ∼12.4nm) which spans a flat detergent micelle. The distance distribution function, P(r) confirms that the WT-CFTR is elongated and with an inhomogeneous electronic density. The F508del-CFTR molecule is also elongated (maximum diameter ∼13.2nm), but the associated detergent micelle hides a larger surface, plausibly related to an increased exposure of hydrophobic portions of the mutated protein. The corresponding P(r) is consistent with the presence of well defined domains, probably linked by flexible regions. These differences suggest that the full-length mutant F508del-CFTR has a detectably different conformation, in contrast to the minor differences observed for the isolated F508-containing domain. We interpret the data in terms of an incomplete post-translational assembly of the protein domains. PMID:26850167

  8. Crucial Role of the Double Bond Isomerism in the Steroid B-Ring on the Membrane Properties of Sterols. Grazing Incidence X-Ray Diffraction and Brewster Angle Microscopy Studies.

    Science.gov (United States)

    Flasiński, Michał; Wydro, Paweł; Broniatowski, Marcin; Hąc-Wydro, Katarzyna; Fontaine, Philippe

    2015-07-01

    Three cholesterol precursors-desmosterol, zymosterol, and lanosterol-were comprehensively characterized in monolayers formed at the air/water interface. The studies were based on registration of the surface pressure (π)-area (A) isotherms complemented with in situ analysis performed with application of modern physicochemical techniques: grazing incidence X-ray diffraction (GIXD) and Brewster angle microscopy (BAM). In this approach we were interested in the correlation between molecular structures of the studied sterols found in the cholesterol biosynthetic pathway and their membrane properties. Our results revealed that only desmosterol behaves in Langmuir monolayers comparably to cholesterol, the molecules of which arrange in the monolayers into a hexagonal lattice, while the two remaining sterols possess extremely different properties. We found that molecules of both zymosterol and lanosterol are organized on the water surface in the two-dimensional oblique unit cells despite the fact that they are oriented perpendicular to the monolayer plane. The comparison of chemical structures of the investigated sterols leads to the conclusion that the only structural motive that can be responsible for such unusual behavior is the double bond in the B sterol ring, which is located in desmosterol in a different position from in the other two sterols. This issue, which was neglected in the scientific literature, seems to have crucial importance for sterol activity in biomembranes. We showed that this structural modification in sterol molecules is directly responsible for their adaptation to proper functioning in biomembranes.

  9. An x-ray detector for time-resolved studies

    International Nuclear Information System (INIS)

    The development of ultrahigh-brightness x-ray sources makes time-resolved x-ray studies more and more feasible. Improvements in x-ray optics components are also critical for obtaining the appropriate beam for a particular type of experiment. Moreover, fast parallel detectors will be essential in order to exploit the combination of high intensity x-ray sources and novel optics for time-resolved experiments. A CCD detector with a time resolution of microseconds has been developed at the Advanced Photon Source (APS). This detector is fully programmable using CAMAC electronics and a Micro Vax computer. The techniques of time-resolved x-ray studies, which include scattering, microradiography, microtomography, stroboscopy, etc., can be applied to a range of phenomena (including rapid thermal annealing, surface ordering, crystallization, and the kinetics of phase transition) in order to understand these time-dependent microscopic processes. Some of these applications will be illustrated by recent results performed at synchrotrons. New powerful x-ray sources now under construction offer the opportunity to apply innovative approaches in time-resolved work

  10. Effects of x-ray does on rhizosphere studies using x-ray computed tomography

    OpenAIRE

    Susan Zappala; Jonathan R Helliwell; Tracy, Saoirse R.; Stefan Mairhofer; Sturrock, Craig J.; Tony Pridmore; Malcolm Bennett; Sacha J. Mooney

    2013-01-01

    X-ray Computed Tomography (CT) is a non-destructive imaging technique originally designed for diagnostic medicine, which was adopted for rhizosphere and soil science applications in the early 1980s. X-ray CT enables researchers to simultaneously visualise and quantify the heterogeneous soil matrix of mineral grains, organic matter, air-filled pores and water-filled pores. Additionally, X-ray CT allows visualisation of plant roots in situ without the need for traditional invasive methods such ...

  11. Identifications studies of Lauha Bhasma by X-ray diffraction and X-ray fluorescence

    Science.gov (United States)

    Bhargava, S. C.; Reddy, K. R. C; Sastry, G. V. S

    2012-01-01

    Procedures for preparation of Lauha Bhasma are described in ancient texts of Ayurveda. These procedures also begin with different source material for iron such as Teekshna Lauha and Kanta Lauha etc. In the present study, we have selected different source materials viz. magnetite iron ore for Kanta Lauha and pure (Armco grade) iron turnings for Teekshna Lauha. The standard procedures of preparation of Lauha Bhasma are carried out in identical conditions for these two raw materials. The final product from the Puta are characterized by using X-ray diffraction and X-ray fluorescence spectroscopy to understanding the crystallographic form or forms of iron oxides and their composition at the end of each Puta. The iron content at the end of repeated Putas (18 for Kanta Lauha and 20 for Teekshna Lauha) have shown a decrease in case of Teekshna Lauha since the starting material is pure iron while it showed only marginal decreases in the case of Kanta Lauha because the Fe3O4 of magnetite is undergoing oxidation to Fe2O3. The trace elements remain within the Bhasma in the form of various oxides of Si, Al, Ca, etc. PMID:23049200

  12. 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.

  13. Limited-angle tomography for analyzer-based phase-contrast x-ray imaging

    International Nuclear Information System (INIS)

    Multiple-image radiography (MIR) is an analyzer-based phase-contrast x-ray imaging method, which is emerging as a potential alternative to conventional radiography. MIR simultaneously generates three planar parametric images containing information about scattering, refraction and attenuation properties of the object. The MIR planar images are linear tomographic projections of the corresponding object properties, which allows reconstruction of volumetric images using computed tomography (CT) methods. However, when acquiring a full range of linear projections around the tissue of interest is not feasible or the scanning time is limited, limited-angle tomography techniques can be used to reconstruct these volumetric images near the central plane, which is the plane that contains the pivot point of the tomographic movement. In this work, we use computer simulations to explore the applicability of limited-angle tomography to MIR. We also investigate the accuracy of reconstructions as a function of number of tomographic angles for a fixed total radiation exposure. We use this function to find an optimal range of angles over which data should be acquired for limited-angle tomography MIR (LAT-MIR). Next, we apply the LAT-MIR technique to experimentally acquired MIR projections obtained in a cadaveric human thumb study. We compare the reconstructed slices near the central plane to the same slices reconstructed by CT-MIR using the full angular view around the object. Finally, we perform a task-based evaluation of LAT-MIR performance for different numbers of angular views, and use template matching to detect cartilage in the refraction image near the central plane. We use the signal-to-noise ratio of this test as the detectability metric to investigate an optimum range of tomographic angles for detecting soft tissues in LAT-MIR. Both results show that there is an optimum range of angular view for data acquisition where LAT-MIR yields the best performance, comparable to CT

  14. Limited-angle tomography for analyzer-based phase-contrast x-ray imaging

    Science.gov (United States)

    Majidi, Keivan; Wernick, Miles N.; Li, Jun; Muehleman, Carol; Brankov, Jovan G.

    2014-07-01

    Multiple-image radiography (MIR) is an analyzer-based phase-contrast x-ray imaging method, which is emerging as a potential alternative to conventional radiography. MIR simultaneously generates three planar parametric images containing information about scattering, refraction and attenuation properties of the object. The MIR planar images are linear tomographic projections of the corresponding object properties, which allows reconstruction of volumetric images using computed tomography (CT) methods. However, when acquiring a full range of linear projections around the tissue of interest is not feasible or the scanning time is limited, limited-angle tomography techniques can be used to reconstruct these volumetric images near the central plane, which is the plane that contains the pivot point of the tomographic movement. In this work, we use computer simulations to explore the applicability of limited-angle tomography to MIR. We also investigate the accuracy of reconstructions as a function of number of tomographic angles for a fixed total radiation exposure. We use this function to find an optimal range of angles over which data should be acquired for limited-angle tomography MIR (LAT-MIR). Next, we apply the LAT-MIR technique to experimentally acquired MIR projections obtained in a cadaveric human thumb study. We compare the reconstructed slices near the central plane to the same slices reconstructed by CT-MIR using the full angular view around the object. Finally, we perform a task-based evaluation of LAT-MIR performance for different numbers of angular views, and use template matching to detect cartilage in the refraction image near the central plane. We use the signal-to-noise ratio of this test as the detectability metric to investigate an optimum range of tomographic angles for detecting soft tissues in LAT-MIR. Both results show that there is an optimum range of angular view for data acquisition where LAT-MIR yields the best performance, comparable to CT

  15. 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

  16. Understanding properties of engineered catalyst supports using contact angle measurements and X-ray reflectivity.

    Science.gov (United States)

    Amama, Placidus B; Islam, Ahmad E; Saber, Sammy M; Huffman, Daniel R; Maruyama, Benji

    2016-02-01

    There is significant interest in broadening the type of catalyst substrates that support the growth of high-quality carbon nanotube (CNT) carpets. In this study, ion beam bombardment has been utilized to modify catalyst substrates for CNT carpet growth. Using a combination of contact angle measurements (CAMs) and X-ray reflectivity (XRR) for the first time, new correlations between the physicochemical properties of pristine and engineered catalyst substrates and CNT growth behavior have been established. The engineered surfaces obtained after exposure to different degrees of ion beam damage have distinct physicochemical properties (porosity, layer thickness, and acid-base properties). The CAM data were analyzed using the van Oss-Chaudhury-Good model, enabling the determination of the acid-base properties of the substrate surfaces. For the XRR data, a Fourier analysis of the interference patterns enabled extraction of layer thickness, while the atomic density and interfacial roughness were extracted by analyzing the amplitude of the interference oscillations. The dramatic transformation of the substrate from "inactive" to "active" is attributed to a combined effect of substrate porosity or damage depth and Lewis basicity. The results reveal that the efficiency of catalyst substrates can be further improved by increasing the substrate basicity, if the minimum surface porosity is established. This study advances the use of a non-thermochemical approach for catalyst substrate engineering, as well as demonstrates the combined utility of CAM and XRR as a powerful, nondestructive, and reliable tool for rational catalyst design.

  17. 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.

  18. Highly Angle-Resolved X-Ray Photoelectron Diffraction from Solid Surfaces

    Science.gov (United States)

    Tamura, K.; Shiraki, S.; Ishii, H.; Owari, M.; Nihei, Y.

    We have carried out the highly angle-resolved X-ray photoelectron diffraction (XPED) measurements by using the input-lens system for restriction of the detection angle. In the input-lens system, high angular resolution and high throughput are accomplished by placing an aperture not on the image plane but on the diffraction plane of electron optics. The aperture sizes (ϕ 4 mm, ϕ 2 mm, ϕ 0.5 mm, ϕ 0.25 mm) correspond to the angular resolutions (± 0.6°, ± 0.3°, ± 0.08°, ± 0.04°) respectively. Highly angle-resolved Ge3d XPED patterns from Ge(111) obtained by the angle-resolving system contain fine structure such as Kikuchi patterns. The fine structure was reproduced by multiple scattering cluster calculations.

  19. 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

  20. 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.

  1. The X-Ray Surveyor Mission: A Concept Study

    Science.gov (United States)

    Gaskin, Jessica A.; Weisskopf, Martin C.; Vikhlinin, Alexey; Tananbaum, Harvey D.; Bandler, Simon R.; Bautz, Marshall W.; Burrows, David N.; Falcone, Abraham D.; Harrison, Fiona A.; Heilmann, Ralf K.; Heinz, Sebastian; Hopkins, Randall C.; Kilbourne, Caroline A.; Kouveliotou, Chryssa; Kraft, Ralph P.; Kravtsov, Andrey V.; McEntaffer, Randall L.; Natarajan, Priyamvada; O'Dell, Stephen L.; Petre, Robert; Prieskorn, Zachary R.; Ptak, Andrew F.; Ramsey, Brian D.; Reid, Paul B.; Schnell, Andrew R.; Schwartz, Daniel A.; Townsley, Leisa K.

    2015-01-01

    NASA's Chandra X-ray Observatory continues to provide an unparalleled means for exploring the high-energy universe. With its half-arcsecond angular resolution, Chandra studies have deepened our understanding of galaxy clusters, active galactic nuclei, galaxies, supernova remnants, neutron stars, black holes, and solar system objects. As we look beyond Chandra, it is clear that comparable or even better angular resolution with greatly increased photon throughput is essential to address ever more demanding science questions-such as the formation and growth of black hole seeds at very high redshifts; the emergence of the first galaxy groups; and details of feedback over a large range of scales from galaxies to galaxy clusters. Recently, we initiated a concept study for such a mission, dubbed X-ray Surveyor. The X-ray Surveyor strawman payload is comprised of a high-resolution mirror assembly and an instrument set, which may include an X-ray microcalorimeter, a high-definition imager, and a dispersive grating spectrometer and its readout. The mirror assembly will consist of highly nested, thin, grazing-incidence mirrors, for which a number of technical approaches are currently under development-including adjustable X-ray optics, differential deposition, and new polishing techniques applied to a variety of substrates. This study benefits from previous studies of large missions carried out over the past two decades and, in most areas, points to mission requirements no more stringent than those of Chandra.

  2. 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.

  3. Low-angle X-ray scattering properties of irradiated spices

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, A.P.G. [Nuclear Instrumentation Laboratory (LIN/COPPE), P. O. Box 68509, 21945-970, Rio de Janeiro RJ (Brazil)], E-mail: delson@lin.ufrj.br; Braz, D. [Nuclear Instrumentation Laboratory (LIN/COPPE), P. O. Box 68509, 21945-970, Rio de Janeiro RJ (Brazil); Barroso, R.C. [Physics Institute (IF/UERJ), University of Rio de Janeiro State, 20550-900 Rio de Janeiro RJ (Brazil); Lopes, R.T. [Nuclear Instrumentation Laboratory (LIN/COPPE), P. O. Box 68509, 21945-970, Rio de Janeiro RJ (Brazil)

    2007-09-21

    The scattering of X-rays at low angles (LAXS) is a technique dominated by the coherent scattering process. One characteristic observation of low-angle coherent scattering is the so-called molecular interference effect, being characterized by the presence of one or more peaks in the forward direction of scattering. In the present study, LAXS profiles from five different spices are carefully measured in order to establish characteristic scattering signatures. Samples of Ceylon cinnamon, cumin, nutmeg, paprika and black pepper were bought in local market in Rio de Janeiro, Brazil. The LAXS patterns were obtained using a Shimadzu DRX 6000 diffractometer in reflection geometry. Coherent scattering patterns are measured for the samples for {theta}=5-35{sup o}. The data were collected in 0.05{sup o} increments every 3 s. In order to evaluate the possible molecular structure changes caused to the irradiation procedure, the signatures obtained for control (non-irradiated) spices were compared with spice samples irradiated with different doses varying from 3 to 40 kGy. The LAXS patterns of all samples were obtained after 30, 60, 90, 120 days to evaluate the effect of storage period. Scattering profiles from spices irradiated with different irradiation doses were obtained and the results compared. For each spice, there is no considerable deviation in shape in function of the irradiation dose. It indicates that the molecular structure of each analyzed spices is preserved considering the dose range chosen. The results show that the molecular structure was found to be stable during storage at the ambient temperature for up to 4 months.

  4. 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.

  5. Low-angle X-ray scattering properties of irradiated spices

    Science.gov (United States)

    Almeida, A. P. G.; Braz, D.; Barroso, R. C.; Lopes, R. T.

    2007-09-01

    The scattering of X-rays at low angles (LAXS) is a technique dominated by the coherent scattering process. One characteristic observation of low-angle coherent scattering is the so-called molecular interference effect, being characterized by the presence of one or more peaks in the forward direction of scattering. In the present study, LAXS profiles from five different spices are carefully measured in order to establish characteristic scattering signatures. Samples of Ceylon cinnamon, cumin, nutmeg, paprika and black pepper were bought in local market in Rio de Janeiro, Brazil. The LAXS patterns were obtained using a Shimadzu DRX 6000 diffractometer in reflection geometry. Coherent scattering patterns are measured for the samples for θ=5-35°. The data were collected in 0.05° increments every 3 s. In order to evaluate the possible molecular structure changes caused to the irradiation procedure, the signatures obtained for control (non-irradiated) spices were compared with spice samples irradiated with different doses varying from 3 to 40 kGy. The LAXS patterns of all samples were obtained after 30, 60, 90, 120 days to evaluate the effect of storage period. Scattering profiles from spices irradiated with different irradiation doses were obtained and the results compared. For each spice, there is no considerable deviation in shape in function of the irradiation dose. It indicates that the molecular structure of each analyzed spices is preserved considering the dose range chosen. The results show that the molecular structure was found to be stable during storage at the ambient temperature for up to 4 months.

  6. Large-angle x-ray scatter in Talbot–Lau interferometry for breast imaging

    International Nuclear Information System (INIS)

    Monte Carlo simulations were used to investigate large-angle x-ray scatter at design energy of 25 keV during small field of view (9.6 cm × 5 cm) differential phase contrast imaging of the breast using Talbot–Lau interferometry. Homogenous, adipose and fibroglandular breasts of uniform thickness ranging from 2 to 8 cm encompassing the field of view were modeled. Theoretically determined transmission efficiencies of the gratings were used to validate the Monte Carlo simulations, followed by simulations to determine the x-ray scatter reaching the detector. The recorded x-ray scatter was classified into x-ray photons that underwent at least one Compton interaction (incoherent scatter) and Rayleigh interaction alone (coherent scatter) for further analysis. Monte Carlo based estimates of transmission efficiencies showed good correspondence (r2>0.99) with theoretical estimates. Scatter-to-primary ratio increased with increasing breast thickness, ranging from 0.11 to 0.22 for 2–8 cm thick adipose breasts and from 0.12 to 0.28 for 2–8 cm thick fibroglandular breasts. The analyzer grating reduced incoherent scatter by ∼18% for 2 cm thick adipose breast and by ∼35% for 8 cm thick fibroglandular breast. Coherent scatter was the dominant contributor to the total scatter. Coherent-to-incoherent scatter ratio ranged from 2.2 to 3.1 for 2–8 cm thick adipose breasts and from 2.7 to 3.4 for 2–8 cm thick fibroglandular breasts. (paper)

  7. 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.

  8. 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.

  9. X-ray tomography studies of prehistoric ceramic artifacts

    International Nuclear Information System (INIS)

    X-ray Computed Tomography (CT) is a powerful non-destructive technique that can yield interesting structural information not discernible through visual examination only. This paper presents the results of the CT scans of four objects belonging to the Romanian cultural heritage attributed to the Vinca, Cucuteni and Cruceni-Belegis cultures. The study was performed with an X-ray tomographic device developed at the Department for Applied Nuclear Physics from Horia Hulubei National Institute for Nuclear Physics and Engineering in Magurele, Romania. This apparatus was specially designed for archaeometric studies of low-Z artifacts: ceramic, wood, bone. The tomographic investigations revealed the internal configuration of the objects and provided information about the degree to which the previous manipulations affected the archaeological items. Based on the X-ray images resulting from the CT scans, hints about the techniques used in the manufacturing of the artifacts were obtained, as well as some indications useful for conservation/restoration purposes. (author)

  10. In situ X-ray studies of film cathodes for solid oxide fuel cells

    International Nuclear Information System (INIS)

    Highlights: •Synchrotron X-rays are used to study in operando the structural and chemical changes of LSM and LSCF film cathodes during half-cell operations. •A-site and B-site cations actively segregate or desegregate on the changes of temperature, pO2, and electrochemical potential. •Chemical lattice expansions show that oxygen-cathode interface is the primary source of rate-limiting processes. •The surface and subsurface of the LSM and LSCF films have different oxidation-states due to vacancy concentration changes. •Liquid-phase infiltration and coarsening processes of cathode materials into porous YSZ electrolyte backbone were monitored by USAXS. -- Abstract: Synchrotron-based X-ray techniques have been used to study in situ the structural and chemical changes of film cathodes during half-cell operations. The X-ray techniques used include X-ray reflectivity (XR), total-reflection X-ray fluorescence (TXRF), high-resolution diffraction (HRD), ultra-small angle X-ray scattering (USAXS). The epitaxial thin film model cathodes for XR, TXRF, and HRD measurements are made by pulse laser deposition and porous film cathodes for USAX measurements are made by screen printing technique. The experimental results reviewed here include A-site and B-site segregations, lattice expansion, oxidation-state changes during cell operations and liquid-phase infiltration and coarsening of cathode to electrolyte backbone

  11. Analysis of the Data from Compton X-ray Polarimeters which Measure the Azimuthal and Polar Scattering Angles

    CERN Document Server

    ,

    2011-01-01

    X-ray polarimetry has the potential to make key-contributions to our understanding of galactic compact objects like binary black hole systems and neutron stars, and extragalactic objects like active galactic nuclei, blazars, and neutron stars. Furthermore, several particle astrophysics topics can be addressed including uniquely sensitive tests of Lorentz invariance. In the energy range from 10-20 keV to several MeV, Compton polarimeters achieve the best performance. In this paper we evaluate the benefit that comes from using the azimuthal and polar angles of the Compton scattered photons in the analysis, rather than using the azimuthal scattering angles alone. We study the case of an ideal Compton polarimeter and show that a Maximum Likelihood analysis which uses the two scattering angles lowers the Minimum Detectable Polarization (MDP) by ~20% compared to a standard analysis based on the azimuthal scattering angles alone. The accuracies with which the polarization fraction and the polarization direction can ...

  12. Soft X-ray Absorbers Enabling Study of the Diffuse X-ray Background Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Absorbers for soft x-rays need to be made thinner and with larger area, to collect more photons, and with minimal number of support stems. However, the structure is...

  13. Coherent X-ray diffraction studies of mesoscopic materials

    Energy Technology Data Exchange (ETDEWEB)

    Shabalin, Anatoly

    2015-12-15

    This thesis is devoted to three separate projects, which can be considered as independent. First, the dynamical scattering effects in the Coherent X-ray Diffractive Imaging (CXDI) method are discussed. Based on the simulation results, a straightforward method for correction for the refraction and absorption artifacts in the Bragg CXDI reconstruction is suggested. The second part summarizes the results of an Coherent X-ray Diffractive Imaging experiment with a single colloidal crystal grain. A remarkable result is that positions of individual particles in the crystal lattice have been resolved in three dimensions. The third project is devoted to X-ray diffraction experimental studies of structural evolution of colloidal crystalline films upon incremental heating. Based on the results of the analysis a model of structural evolution of a colloidal crystal upon heating on nanoscopic and mesoscopic length scales is suggested.

  14. Coherent X-ray diffraction studies of mesoscopic materials

    International Nuclear Information System (INIS)

    This thesis is devoted to three separate projects, which can be considered as independent. First, the dynamical scattering effects in the Coherent X-ray Diffractive Imaging (CXDI) method are discussed. Based on the simulation results, a straightforward method for correction for the refraction and absorption artifacts in the Bragg CXDI reconstruction is suggested. The second part summarizes the results of an Coherent X-ray Diffractive Imaging experiment with a single colloidal crystal grain. A remarkable result is that positions of individual particles in the crystal lattice have been resolved in three dimensions. The third project is devoted to X-ray diffraction experimental studies of structural evolution of colloidal crystalline films upon incremental heating. Based on the results of the analysis a model of structural evolution of a colloidal crystal upon heating on nanoscopic and mesoscopic length scales is suggested.

  15. 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.

  16. Nano structured materials studied by coherent X-ray diffraction

    International Nuclear Information System (INIS)

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

  17. Nano structured materials studied by coherent X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Gulden, Johannes

    2013-03-15

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

  18. Cardiac motion correction based on partial angle reconstructed images in x-ray CT

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seungeon; Chang, Yongjin; Ra, Jong Beom, E-mail: jbra@kaist.ac.kr [Department of Electrical Engineering, KAIST, Daejeon 305-701 (Korea, Republic of)

    2015-05-15

    Purpose: Cardiac x-ray CT imaging is still challenging due to heart motion, which cannot be ignored even with the current rotation speed of the equipment. In response, many algorithms have been developed to compensate remaining motion artifacts by estimating the motion using projection data or reconstructed images. In these algorithms, accurate motion estimation is critical to the compensated image quality. In addition, since the scan range is directly related to the radiation dose, it is preferable to minimize the scan range in motion estimation. In this paper, the authors propose a novel motion estimation and compensation algorithm using a sinogram with a rotation angle of less than 360°. The algorithm estimates the motion of the whole heart area using two opposite 3D partial angle reconstructed (PAR) images and compensates the motion in the reconstruction process. Methods: A CT system scans the thoracic area including the heart over an angular range of 180° + α + β, where α and β denote the detector fan angle and an additional partial angle, respectively. The obtained cone-beam projection data are converted into cone-parallel geometry via row-wise fan-to-parallel rebinning. Two conjugate 3D PAR images, whose center projection angles are separated by 180°, are then reconstructed with an angular range of β, which is considerably smaller than a short scan range of 180° + α. Although these images include limited view angle artifacts that disturb accurate motion estimation, they have considerably better temporal resolution than a short scan image. Hence, after preprocessing these artifacts, the authors estimate a motion model during a half rotation for a whole field of view via nonrigid registration between the images. Finally, motion-compensated image reconstruction is performed at a target phase by incorporating the estimated motion model. The target phase is selected as that corresponding to a view angle that is orthogonal to the center view angles of

  19. Wide Angle X-ray Sky Monitoring for Corroborating non-Electromagnetic Cosmic Transients

    CERN Document Server

    Guetta, Dafne

    2010-01-01

    Gravitational waves (GW) can be emitted from coalescing neutron star (NS) and black hole-neutron star (BH-NS) binaries, which are thought to be the sources of short hard gamma ray bursts (SHBs). The gamma ray fireballs seem to be beamed into a small solid angle and therefore only a fraction of detectable GW events is expected to be observationally coincident with SHBs. Similarly ultrahigh energy (UHE) neutrino signals associated with gamma ray bursts (GRBs) could fail to be corroborated by prompt gamma-ray emission if the latter is beamed in a narrower cone than the neutrinos. Alternative ways to corroborate non-electromagnetic signals from coalescing neutron stars are therefore all the more desirable. It is noted here that the extended X-ray tails (XRT) of SHBs are similar to X-ray flashes (XRFs), and that both can be attributed to an off-axis line of sight and thus span a larger solid angle than the hard emission. It is proposed that a higher fraction of detectable GW events may be coincident with XRF/XRT t...

  20. 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.

  1. X-ray study of weak interactions in two flavonoids

    Indian Academy of Sciences (India)

    Deepak Sharma; Vivek K Gupta; Goutam Brahmachari; Sadhan Mondal; Arindam Gangopadhyay

    2007-10-01

    X-ray diffraction studies were carried out on single crystals of two flavonoids, viz. 5-hydroxy-6,7,4′-trimethoxyflavone, C18H16O6, (I) and 5-hydroxy-3,7,4′-trimethoxyflavone, C18H16O6, (II). Crystal structures of both the flavonoids were solved by direct methods and refined by full-matrix least-squares procedures. In both the molecules, the benzopyran moiety is planar. The dihedral angle between the phenyl ring and the benzopyran portion is 5.50(4)° in (I) and 29.11(5)° in (II). In (I), the crystal packing is influenced by O–H…O hydrogen bonds, and weak C–H…O and $\\pi \\ldots \\pi$ interactions whereas in (II) the crystal structure is stabilized by the presence of four intermolecular short contacts of the type C–H…O. There is also one C–H$\\ldots \\pi$ hydrogen bond with H… centroid distance of < 2.7 Å. The molecules are further stabilized by – interactions.

  2. 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

  3. Powder X-ray diffraction study af alkali alanates

    DEFF Research Database (Denmark)

    Cao, Thao; Mosegaard Arnbjerg, Lene; Jensen, Torben René

    Powder X-ray diffraction study of alkali alanates Thao Cao, Lene Arnbjerg, Torben R. Jensen. Center for Materials Crystallography (CMC), Center for Energy Materials (CEM), iNANO and Department of Chemistry, Aarhus University, DK-8000, Denmark. Abstract: To meet the energy demand in the future...

  4. Crystal defect studies using x-ray diffuse scattering

    Energy Technology Data Exchange (ETDEWEB)

    Larson, B.C.

    1980-01-01

    Microscopic lattice defects such as point (single atom) defects, dislocation loops, and solute precipitates are characterized by local electronic density changes at the defect sites and by distortions of the lattice structure surrounding the defects. The effect of these interruptions of the crystal lattice on the scattering of x-rays is considered in this paper, and examples are presented of the use of the diffuse scattering to study the defects. X-ray studies of self-interstitials in electron irradiated aluminum and copper are discussed in terms of the identification of the interstitial configuration. Methods for detecting the onset of point defect aggregation into dislocation loops are considered and new techniques for the determination of separate size distributions for vacancy loops and interstitial loops are presented. Direct comparisons of dislocation loop measurements by x-rays with existing electron microscopy studies of dislocation loops indicate agreement for larger size loops, but x-ray measurements report higher concentrations in the smaller loop range. Methods for distinguishing between loops and three-dimensional precipitates are discussed and possibilities for detailed studies considered. A comparison of dislocation loop size distributions obtained from integral diffuse scattering measurements with those from TEM show a discrepancy in the smaller sizes similar to that described above.

  5. [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

  6. X-ray and neutron scattering studies of complex confined fluids.

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, S. K.

    1999-08-04

    We review recent X-ray and neutron scattering studies of the structure and dynamics of confined complex fluids. This includes the study of polymer conformations and binary fluid phase transitions in porous media using Small Angle Neutron scattering, and the use of synchrotrons radiation to study ordering and fluctuation phenomena at solid/liquid and liquid/air interfaces. Ordering of liquids near a solid surface or in confinement will be discussed, and the study, via specular and off-specular X-ray reflectivity, of capillary wave fluctuations on liquid polymer films. Finally, we shall discuss the use of high-brilliance beams from X-ray synchrotrons to study via photon correlation spectroscopy the slow dynamics of soft condensed matter systems.

  7. GLANCING INCIDENCE X-RAY STUDIES OF TITANIUM NITRIDE THIN FILMS USING A NEW MULTIPURPOSE LABORATORY SPECTROMETER

    OpenAIRE

    Buschert, R.C; Gibson, P.; Gissler, W.; Haupt, J.; Crabb, T.

    1989-01-01

    A multipurpose laboratory glancing angle X-ray spectrometer using a standard X-ray tube and a germanium solid state detector has been designed for vertical and horizontal diffraction scans, reflectivity and glancing angle fluorescence measurements. It has been used to study titanium nitride thin films grown under various conditions that vary the stoichiometry, strain, grain size, orientation and lattice parameter. In particular, films grown at liquid nitrogen substrate temperature show very h...

  8. Understanding nucleic acid structural changes by comparing wide-angle x-ray scattering (WAXS) experiments to molecular dynamics simulations

    Science.gov (United States)

    Pabit, Suzette A.; Katz, Andrea M.; Tolokh, Igor S.; Drozdetski, Aleksander; Baker, Nathan; Onufriev, Alexey V.; Pollack, Lois

    2016-05-01

    Wide-angle x-ray scattering (WAXS) is emerging as a powerful tool for increasing the resolution of solution structure measurements of biomolecules. Compared to its better known complement, small angle x-ray scattering (SAXS), WAXS targets higher scattering angles and can enhance structural studies of molecules by accessing finer details of solution structures. Although the extension from SAXS to WAXS is easy to implement experimentally, the computational tools required to fully harness the power of WAXS are still under development. Currently, WAXS is employed to study structural changes and ligand binding in proteins; however, the methods are not as fully developed for nucleic acids. Here, we show how WAXS can qualitatively characterize nucleic acid structures as well as the small but significant structural changes driven by the addition of multivalent ions. We show the potential of WAXS to test all-atom molecular dynamics (MD) simulations and to provide insight into understanding how the trivalent ion cobalt(III) hexammine (CoHex) affects the structure of RNA and DNA helices. We find that MD simulations capture the RNA structural change that occurs due to addition of CoHex.

  9. Understanding Nucleic Acid Structural Changes by Comparing Wide-Angle X-ray Scattering (WAXS) Experiments to Molecular Dynamics Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pabit, Suzette; Katz, Andrea M.; Tolokh, Igor S.; Drozdetski, Aleksander; Baker, Nathan A.; Onufriev, Alexey; Pollack, Lois

    2016-05-24

    Wide-angle x-ray scattering (WAXS) is emerging as a powerful tool for increasing the resolution of solution structure measurements of biomolecules. Compared to its better known complement, small angle x-ray scattering (SAXS), WAXS targets higher scattering angles and can enhance structural studies of molecules by accessing finer details of solution structures. Although the extension from SAXS to WAXS is easy to implement experimentally, the computational tools required to fully harness the power of WAXS are still under development. Currently, WAXS is employed to study structural changes and ligand binding in proteins; however the methods are not as fully developed for nucleic acids. Here, we show how WAXS can qualitatively char- acterize nucleic acid structures as well as the small but significant structural changes driven by the addition of multivalent ions. We show the potential of WAXS to test all-atom molecular dynamics (MD) simulations and to provide insight in understanding how the trivalent ion cobalt(III) hexammine (CoHex) affects the structure of RNA and DNA helices. We find that MD simulations capture the RNA structural change that occurs due to addition of CoHex.

  10. A Joint GMRT/X-ray study of galaxy groups

    CERN Document Server

    O'Sullivan, E; Vrtilek, J M; Raychaudhuri, S; Athreya, R; Venturi, T; David, L P

    2009-01-01

    We present results from combined low-frequency radio and X-ray studies of nearby galaxy groups. We consider two main areas: firstly, the evolutionary process from spiral-dominated, HI-rich groups to elliptical-dominated systems with hot, X-ray emitting gas halos; secondly, the mechanism of AGN feedback which appears to balance radiative cooling of the hot halos of evolved groups. The combination of radio and X-ray observations provides a powerful tool for these studies, allowing examination of gas in both hot and cool phases, and of the effects of shock heating and AGN outbursts. Low-frequency radio data are effective in detecting older and less energetic electron populations and are therefore vital for the determination of the energetics and history of such events. We present results from our ongoing study of Stephan's Quintet, a spiral-rich group in which tidal interactions and shock heating appear to be transforming HI in the galaxies into a diffuse X-ray emitting halo, and show examples of AGN feedback fr...

  11. Studying planetary matter using intense x-ray pulses

    Science.gov (United States)

    Appel, K.; Nakatsutsumi, M.; Pelka, A.; Priebe, G.; Thorpe, I.; Tschentscher, Th

    2015-01-01

    Free-electron laser facilities enable new applications in the field of high-pressure research including planetary materials. The European x-ray Free Electron Laser (European XFEL) in Hamburg, Germany will start user operation in 2017 and will provide photon energies of up to 25 keV. The high-energy density science instrument (HED) is one of the six baseline instruments at the European XFEL. It is dedicated to the study of dense material at strong excitation in a temperature range from eV to keV and pressures >100 GPa which is equivalent to an energy density >100 J mm-3. It will enable studying structural and electronic properties of excited states with hard x-rays. The instrument is currently in its technical design phase and first user experiments are foreseen for summer 2017. In this contribution, we present the x-ray instrumentation and foreseen x-ray techniques at HED and concentrate on prototype hard-condensed matter experiments in the field of planetary research as proposed during recent user consortium meetings for this instrument. These include quasi-isentropic (ramped) compression and shock compression experiments.

  12. A Furnace for Diffraction Studies using Synchrotron X-Ray Radiation

    DEFF Research Database (Denmark)

    Buras, B.; Lebech, Bente; Kofoed, W.

    1984-01-01

    A furnace for diffraction studies using synchrotron X-ray radiation is described. The furnace can be operated between ambient temperature and 1 800 °C with a temperature stability better than 5 °C for temperatures above 300 °C. Kapton windows allow almost 360° access for the X-ray beam...... in the horizontal scattering plane and the furnace may be used in both conventional monochromatic beam angle-dispersive and white-beam energy-dispersive diffraction experiments. Details of the furnace windows, heating element, thermometry and sample mount are given....

  13. Introducing a standard method for experimental determination of the solvent response in laser pump, x-ray probe time-resolved wide-angle x-ray scattering experiments on systems in solution

    DEFF Research Database (Denmark)

    Kjær, Kasper Skov; Brandt van Driel, Tim; Kehres, Jan;

    2013-01-01

    In time-resolved laser pump, X-ray probe wide-angle X-ray scattering experiments on systems in solution the structural response of the system is accompanied by a solvent response. The solvent response is caused by reorganization of the bulk solvent following the laser pump event, and in order...... response-the solvent term-experimentally when applying laser pump, X-ray probe time-resolved wide-angle X-ray scattering. The solvent term describes difference scattering arising from the structural response of the solvent to changes in the hydrodynamic parameters: pressure, temperature and density. We...... is demonstrated to exhibit first order behaviour with respect to the amount of energy deposited in the solution. We introduce a standardized method for recording solvent responses in laser pump, X-ray probe time-resolved X-ray wide-angle scattering experiments by using dye mediated solvent heating. Furthermore...

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. X-ray imaging in advanced studies of ophthalmic diseases.

    Science.gov (United States)

    Antunes, Andrea; Safatle, Angélica M V; Barros, Paulo S M; Morelhão, Sérgio L

    2006-07-01

    Microscopic characterization of pathological tissues has one major intrinsic limitation, the small sampling areas with respect to the extension of the tissues. Mapping possible changes on vast tissues and correlating them with large ensembles of clinical cases is not a feasible procedure for studying most diseases, as for instance vision loss related diseases and, in particular, the cataract. Although intraocular lens implants are successful treatments, cataract still is a leading public-health issue that grows in importance as the population increases and life expectancy is extended worldwide. In this work we have exploited the radiation-tissue interaction properties of hard x-rays--very low absorption and scattering--to map distinct lesions on entire eye lenses. At the used synchrotron x-ray photon energy of 20 keV (wavelength lambda=0.062 nm), scattering and refraction are angular resolved effects. It allows the employed x-ray image technique to efficiently characterize two types of lesions in eye lenses under cataractogenesis: distributions of tiny scattering centers and extended areas of fiber cell compaction. The data collection procedure is relatively fast; allowing dozens of samples to be totally imaged (scattering, refraction, and mass absorption images) in a single day of synchrotron beam time. More than 60 cases of canine cataract, not correlated to specific causes, were investigated in this first application of x-rays to image entire lenses. Cortical opacity cases, or partial opacity, could be related to the presence of calcificated tissues at the cortical areas, clearly visible in the images, whose elemental contents were verified by micro x-ray fluorescence as very rich in calcium. Calcificated tissues were also observed at nuclear areas in some cases of hypermature cataract. Total opacity cases without distinguishable amount of scattering centers consist in 70% of the analyzed cases, where remarkable fissure marks owing to extended areas of fiber

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. Momentum-resolved electronic structure at a buried interface from soft X-ray standing-wave angle-resolved photoemission

    NARCIS (Netherlands)

    Gray, A.X.; Minar, J.; Plucinski, L.; Huijben, M.; Bostwick, A.; Rotenberg, E.; Yang, S.-H.; Braun, J.; Winkelmann, A.; Conti, G.; Eiteneer, D.; Rattanachata, A.; Greer, A.A.; Ciston, J.; Ophus, C.; Rijnders, A.J.H.M.; Blank, D.H.A.; Doennig, D.; Pentcheva, R.; Kortright, J.B.; Schneider, C.M.; Ebert, H.; Fadley, C.S.

    2013-01-01

    Angle-resolved photoemission spectroscopy (ARPES) is a powerful technique for the study of electronic structure, but it lacks a direct ability to study buried interfaces between two materials. We address this limitation by combining ARPES with soft X-ray standing-wave (SW) excitation (SWARPES), in w

  4. X-RAY SCATTERING STUDIES ON NYLON-1010

    Institute of Scientific and Technical Information of China (English)

    MO Zhishen; YANG Baoquan; XUE Xiaofu; ZHANG Lihua

    1992-01-01

    From Wide-Angle X-ray Scattering (WAXS) pattern of uniaxially orientated fibers, the crystal structure of Nylon-1010 was determined. The Nylon-1010 crystallizes in the tricllinic system, with lattice dimensions: a=4.9A, b=5.4A, c=27.8A, α=49 °, β=77 °,γ=63.5 °, the unit cell contains one monomeric unit and the space group is P1. The degree of crystallinity of polymer was determined as about 60%, using Ruland's method.The structures of Nylon-1010 with different draw ratio have been investigated by using Small-Angle X-ray Scattering (SAXS). The results indicate that the draw ratio of samples has a significant effect on microstructure of Nylon-1010. The long period and thickness of amorphous layer obviously increase but the invariant, average lamellar and interphase zone show almost independent of draw ratio, long period increases because amorphous layer increases with draw ratio. The electron density fluctuation values increased with draw ratio, but inner surface Os is drecreased.

  5. X-ray and neutron diffraction studies of chalcocite oxidation

    International Nuclear Information System (INIS)

    Full text: The mineral chalcocite (Cu2S), which is often found in the enriched zone of sulphide deposits, is an important source of copper. The oxidation behaviour of chalcocite is of interest in terms of the mineral exploration technology and also for understanding the behaviour of the mineral under roasting conditions. Recently, the oxidation of chalcocite was the subject of a study by Dunn et al (1994) involving the use of thermal analysis, scanning electron microscopy, electron probe microanalysis, powder x-ray diffraction (XRD) and Fourier transform spectroscopy. The study indicated that the following transformations are likely to occur: at 430-490 deg C, partial conversion of Cu2S to Cu2O and CuSO4 via Cu1.96S and Cu1.80S; at 490-590 deg C, further conversion of Cu2S to Cu2O, CuO CuSO4 and CuSO4; and at 590-820 deg C, Cu2O, CuO CuSO4 and CuSO4 to CuO. In this study, the oxidation of chalcocite was analysed from a crystallographic perspective. Ambient x-ray diffraction and in-situ neutron diffraction were used to determine the phases present, at various temperatures, as oxidation progressed. Ambient x-ray experiments involved heating chalcocite powder in an air stream, to a target temperature, cooling it to room temperature in a nitrogen stream, and analysing by Bragg-Brentano x-ray powder diffractometry. In situ neutron experiments consisted of, powdered chalcocite being heated in an air stream to various target temperatures, and then held in a nitrogen stream at the given temperature while Medium Resolution Powder Diffractometry (EPD) was performed. Rietveld modelling of the x-ray and neutron data was used to confirm the phase identifications made by search/match analysis, and to then map the variations in phase levels with temperature as the oxidation progresses through various phase transformations. The talk will consider the results obtained from the study with particular reference to the identification of previously undetected phases, and the differences

  6. 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.

  7. X-ray absorption studies of battery materials

    Energy Technology Data Exchange (ETDEWEB)

    McBreen, J.

    1996-10-01

    X-ray absorption spectroscopy (XAS) is ideal for {ital in}{ital situ} studies of battery materials because both the probe and signal are penetrating x rays. The advantage of XAS being element specific permits investigation of the environment of a constituent element in a composite material. This makes it very powerful for studying electrode additives and corrosion of individual components of complex metal hydride alloys. The near edge part of the spectrum (XANES) provides information on oxidation state and site symmetry of the excited atom. This is particularly useful in study of corrosion and oxidation changes in cathode materials during charge/discharge cycle. Extended fine structure (EXAFS) gives structural information. Thus the technique provides both chemical and structural information. Since XAS probes only short range order, it can be applied to study of amorphous electrode materials and electrolytes. This paper discusses advantages and limitations of the method, as well as some experimental aspects.

  8. X-Ray Study of Pressure-Collapsed Fullerite

    OpenAIRE

    Kosowsky, S. D.; Hsu, C.-H.; Chen, Nancy H.; Moshary, Fred; Pershan, Peter S.; Silvera, Isaac F.

    1993-01-01

    X-ray-diffraction studies are described for a new phase of carbon called collapsed fullerite (CF) that was produced by application of high pressure to fullerite (C\\(_{60}\\)). At \\(\\sim\\)20 GPa there is an irreversible transition to a phase that has neither the (111) Bragg peak of diamond nor any of the Bragg peaks associated with the fcc phase of C\\(_{60}\\). The spectrum of CF is flat and featureless in the range of study.

  9. The NASA X-Ray Mission Concepts Study

    Science.gov (United States)

    Petre, Robert; Ptak, A.; Bookbinder, J.; Garcia, M.; Smith, R.; Bautz, M.; Bregman, J.; Burrows, D.; Cash, W.; Jones-Forman, C.; Murray, S.; Plucinsky, P.; Ramsey, B.; Remillard, R.; Wilson-Hodge, C.; Daelemans, G.; Karpati, G.; Nicoletti, A.; Reid, P.

    2012-01-01

    The 2010 Astrophysics Decadal Survey recommended a significant technology development program towards realizing the scientific goals of the International X-ray Observatory (IXO). NASA has undertaken an X-ray mission concepts study to determine alternative approaches to accomplishing IXO's high ranking scientific objectives over the next decade given the budget realities, which make a flagship mission challenging to implement. The goal of the study is to determine the degree to which missions in various cost ranges from $300M to $2B could fulfill these objectives. The study process involved several steps. NASA released a Request for Information in October 2011, seeking mission concepts and enabling technology ideas from the community. The responses included a total of 14 mission concepts and 13 enabling technologies. NASA also solicited membership for and selected a Community Science Team (CST) to guide the process. A workshop was held in December 2011 in which the mission concepts and technology were presented and discussed. Based on the RFI responses and the workshop, the CST then chose a small group of notional mission concepts, representing a range of cost points, for further study. These notional missions concepts were developed through mission design laboratory activities in early 2012. The results of all these activities were captured in the final X-ray mission concepts study report, submitted to NASA in July 2012. In this presentation, we summarize the outcome of the study. We discuss background, methodology, the notional missions, and the conclusions of the study report.

  10. Future lunar mission Active X-ray Spectrometer development: Surface roughness and geometry studies

    Science.gov (United States)

    Naito, M.; Hasebe, N.; Kusano, H.; Nagaoka, H.; Kuwako, M.; Oyama, Y.; Shibamura, E.; Amano, Y.; Ohta, T.; Kim, K. J.; Lopes, J. A. M.

    2015-07-01

    The Active X-ray Spectrometer (AXS) is considered as one of the scientific payload candidates for a future Japanese mission, SELENE-2. The AXS consists of pyroelectric X-ray generators and a Silicon Drift Detector to conduct X-Ray Fluorescence spectroscopy (XRF) on the Moon to measure major elements: Mg, Al, Si, Ca, Ti, and Fe; minor elements: Na, K, P, S, Cr and Mn; and the trace element Ni depending on their concentration. Some factors such as roughness, grain size and porosity of sample, and the geometry of X-ray incidence, emission and energy will affect the XRF measurements precision. Basic studies on the XRF are required to develop the AXS. In this study, fused samples were used to make homogeneous samples free from the effect of grain size and porosity. Experimental and numerical studies on the XRF were conducted to evaluate the effects from incidence and emission angles and surface roughness. Angle geometry and surface roughness will be optimized for the design of the AXS on future missions from the results of the experiment and the numerical simulation.

  11. Future lunar mission Active X-ray Spectrometer development: Surface roughness and geometry studies

    International Nuclear Information System (INIS)

    The Active X-ray Spectrometer (AXS) is considered as one of the scientific payload candidates for a future Japanese mission, SELENE-2. The AXS consists of pyroelectric X-ray generators and a Silicon Drift Detector to conduct X-Ray Fluorescence spectroscopy (XRF) on the Moon to measure major elements: Mg, Al, Si, Ca, Ti, and Fe; minor elements: Na, K, P, S, Cr and Mn; and the trace element Ni depending on their concentration. Some factors such as roughness, grain size and porosity of sample, and the geometry of X-ray incidence, emission and energy will affect the XRF measurements precision. Basic studies on the XRF are required to develop the AXS. In this study, fused samples were used to make homogeneous samples free from the effect of grain size and porosity. Experimental and numerical studies on the XRF were conducted to evaluate the effects from incidence and emission angles and surface roughness. Angle geometry and surface roughness will be optimized for the design of the AXS on future missions from the results of the experiment and the numerical simulation

  12. Future lunar mission Active X-ray Spectrometer development: Surface roughness and geometry studies

    Energy Technology Data Exchange (ETDEWEB)

    Naito, M., E-mail: com-nm@akane.waseda.jp [School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo (Japan); Hasebe, N. [School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo (Japan); Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo (Japan); Kusano, H. [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo (Japan); Nagaoka, H. [School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo (Japan); Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo (Japan); Kuwako, M.; Oyama, Y. [School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo (Japan); Shibamura, E.; Amano, Y. [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo (Japan); Ohta, T. [School of Education and Integrated Arts and Science, Waseda University, 1-104 Totsuka, Shinjuku, Tokyo (Japan); Kim, K.J. [Korea Institute of Geoscience and Mineral Resources, Gwahang-no 124, Yuseong-gu, Daejeon 305-350 (Korea, Republic of); Lopes, J.A.M. [Department of Physics, University of Coimbra, Apartado 3020, 3001-401 Coimbra (Portugal); Instituto Superior de Engenharia de Coimbra, 3030-199 Coimbra (Portugal)

    2015-07-11

    The Active X-ray Spectrometer (AXS) is considered as one of the scientific payload candidates for a future Japanese mission, SELENE-2. The AXS consists of pyroelectric X-ray generators and a Silicon Drift Detector to conduct X-Ray Fluorescence spectroscopy (XRF) on the Moon to measure major elements: Mg, Al, Si, Ca, Ti, and Fe; minor elements: Na, K, P, S, Cr and Mn; and the trace element Ni depending on their concentration. Some factors such as roughness, grain size and porosity of sample, and the geometry of X-ray incidence, emission and energy will affect the XRF measurements precision. Basic studies on the XRF are required to develop the AXS. In this study, fused samples were used to make homogeneous samples free from the effect of grain size and porosity. Experimental and numerical studies on the XRF were conducted to evaluate the effects from incidence and emission angles and surface roughness. Angle geometry and surface roughness will be optimized for the design of the AXS on future missions from the results of the experiment and the numerical simulation.

  13. Resonance magnetic x-ray scattering study of erbium

    DEFF Research Database (Denmark)

    Sanyal, M.K.; Gibbs, D.; Bohr, J.;

    1994-01-01

    of this magnetic scattering and analyzed it using a simple model based on electric dipole and quadrupole transitions among atomic orbitals. The line shapes can be fitted to a magnetic structure combining both c-axis-modulated and basal-plane components. Below 18 K, we have observed unusual behavior......The magnetic phases of erbium have been studied by resonance x-ray-scattering techniques. When the incident x-ray energy is tuned near the L(III) absorption edge, large resonant enhancements of the magnetic scattering are observed above 18 K. We have measured the energy and polarization dependence...... of the magnetic scattering as a function of energy, whose origin is not understood....

  14. High-resolution soft-X-ray beamline ADRESS at Swiss Light Source for resonant inelastic X-ray scattering and angle-resolved photoelectron spectroscopies

    CERN Document Server

    Strocov, V N; Flechsig, U; Schmidt, T; Imhof, A; Chen, Q; Raabe, J; Betemps, R; Zimoch, D; Krempasky, J; Piazzalunga, A; Wang, X; Grioni, M; Patthey, L

    2009-01-01

    We describe the concepts and technical realization of the high-resolution soft-X-ray beamline ADRESS operating in the energy range from 300 to 1600 eV and intended for Resonant Inelastic X-ray Scattering (RIXS) and Angle-Resolved Photoelectron Spectroscopy (ARPES). The photon source is an undulator of novel fixed-gap design where longitudinal movement of permanent magnetic arrays controls not only the light polarization (including circular and 0-180 deg rotatable linear polarizations) but also the energy without changing the gap. The beamline optics is based on the well-established scheme of plane grating monochromator (PGM) operating in collimated light. The ultimate resolving power E/dE is above 33000 at 1 keV photon energy. The choice of blazed vs lamellar gratings and optimization of their profile parameters is described. Due to glancing angles on the mirrors as well as optimized groove densities and profiles of the gratings, high photon flux is achieved up to 1.0e13 photons/s/0.01%BW at 1 keV. Ellipsoida...

  15. Simulation studies of atomic resolution X-ray holography

    Indian Academy of Sciences (India)

    Yogesh Kashyap; P S Sarkar; Amar Sinha; B K Godwal

    2004-02-01

    X-ray holography is a new method of structure determination based on measurement of interference of a known reference wave with an unknown object wave (containing information on atomic sites scattering the reference wave) so that phase information is preserved. Unlike X-ray diffraction, it does not demand for translational periodicity in the material. It is based on the idea similar to that of optical holography and has been tested on crystals, quasicrystals, thin films and doped semiconductors for their structure determination. In order to analyse potentials and limitations of this technique, we have carried out theoretical simulation studies on simple structures. In this paper we describe the basic algorithm of hologram generation and reconstruction of atomic positions from generated data. We illustrate this technique using Fe (bcc) single crystal as sample case to demonstrate its capabilities and limitations. Simulations were carried out on the Cu (fcc) structure and on complex structure such as the Al–Pd–Mn quasicrystal. Technical issues such as low signal to noise ratio, twin image problem etc have been discussed briefly to emphasize the need for high intensity X-ray source such as synchrotron for experiments and proper reconstruction algorithm. Finally the scope and potential of this technique have been discussed.

  16. Development of an x-ray beam line at the NSLS for studies in materials science using x-ray absorption spectroscopy: Annual progress report

    International Nuclear Information System (INIS)

    The research programs reported span virtually the entire range of condensed matter studies involving the fields of solid state physics, chemistry, electrochemistry, materials science and biochemistry. Results are discussed for various groups. Topics reported include work on amorphous chalcogenide semiconductors, particularly photostructural changes, kinetics of structural changes and rapid quenching, bond strengths, force constants and phonons. Also reported are temperature dependent EXAFS studies of bonding in high temperature alloys, amorphous systems, disordered alloys and studies of resolve electronic structure, EXAFS and XANES studies of permanent magnet systems based on Nd2Fe14B, glancing angle EXAFS study of Nb/Al and Nb/Si interfacial systems, x-ray absorption of krypton-implanted solids and high dose implants into silicon, and x-ray absorption and EXAFS studies of superconducting oxide compounds of Cu and related magnetic systems. Work is also reported on XAFS measurements on the icosahedral phase

  17. Monitoring the recrystallisation of amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering.

    Science.gov (United States)

    Palomäki, Emmi; Ahvenainen, Patrik; Ehlers, Henrik; Svedström, Kirsi; Huotari, Simo; Yliruusi, Jouko

    2016-07-11

    In this paper we present a fast model system for monitoring the recrystallization of quench-cooled amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering. The use of these two methods enables comparison between surface and bulk crystallization. Non-ordered mesoporous silica micro-particles were added to the system in order to alter the rate of crystallization of the amorphous xylitol. Raman measurements showed that adding silica to the system increased the rate of surface crystallization, while X-ray measurements showed that the rate of bulk crystallization decreased. Using this model system it is possible to measure fast changes, which occur in minutes or within a few hours. Raman-spectroscopy and wide-angle X-ray scattering were found to be complementary techniques when assessing surface and bulk crystallization of amorphous xylitol. PMID:27163527

  18. Accurate small and wide angle x-ray scattering profiles from atomic models of proteins and nucleic acids

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Hung T. [BioMaPS Institute for Quantitative Biology, Rutgers University, Piscataway, New Jersey 08854 (United States); Pabit, Suzette A.; Meisburger, Steve P.; Pollack, Lois [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States); Case, David A., E-mail: case@biomaps.rutgers.edu [BioMaPS Institute for Quantitative Biology, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854 (United States)

    2014-12-14

    A new method is introduced to compute X-ray solution scattering profiles from atomic models of macromolecules. The three-dimensional version of the Reference Interaction Site Model (RISM) from liquid-state statistical mechanics is employed to compute the solvent distribution around the solute, including both water and ions. X-ray scattering profiles are computed from this distribution together with the solute geometry. We describe an efficient procedure for performing this calculation employing a Lebedev grid for the angular averaging. The intensity profiles (which involve no adjustable parameters) match experiment and molecular dynamics simulations up to wide angle for two proteins (lysozyme and myoglobin) in water, as well as the small-angle profiles for a dozen biomolecules taken from the BioIsis.net database. The RISM model is especially well-suited for studies of nucleic acids in salt solution. Use of fiber-diffraction models for the structure of duplex DNA in solution yields close agreement with the observed scattering profiles in both the small and wide angle scattering (SAXS and WAXS) regimes. In addition, computed profiles of anomalous SAXS signals (for Rb{sup +} and Sr{sup 2+}) emphasize the ionic contribution to scattering and are in reasonable agreement with experiment. In cases where an absolute calibration of the experimental data at q = 0 is available, one can extract a count of the excess number of waters and ions; computed values depend on the closure that is assumed in the solution of the Ornstein–Zernike equations, with results from the Kovalenko–Hirata closure being closest to experiment for the cases studied here.

  19. Retrospective epidemiological study of the X-Ray exposure

    International Nuclear Information System (INIS)

    There are a large amount of epidemiological studies nowadays in the world which are devoted to the analysis of the medical effects and the radiation risk. But a few of them deal with the analysis of the medical diagnostic radiation influence on health. It is appropriate, for the large compared contingent of the patients and the possibility of comparing them in several decades after the exposure are necessary for the evaluation of the influence of small doses on health. Meanwhile the X-ray exposure of the population is one of the most important types of radiation influence among all the kinds and sources of radiation. It is characterized by high dose rate and the possibility of multiple influence on a weakened and diseased organism. In connection with that, the eleven of the indices of population health was analyzed for the first time in Russia. The population was influenced by different levels of X-ray exposure 10-50 years ago. The research was carried out in the two groups of the Tumen (Siberia) regions. These regions are more or less equal in the climatic; ecologic, social-economic and demographic conditions. Nevertheless, they are different even only in the value of accumulated doses of X-ray exposure of the population (mostly in 50-70s) more than three times. Disease and mortality cancer of population of the last ten years in the regions were analyzed. The regions were selected taking into account the absence of the influence of other possible negative environmental factors. The data are found as the result of the dosimetric and epidemiological studies, and the processing of the archive statistic information. These researches demonstrated that on the whole there is the considerable statistically proved rise of disease cancer in the regions with high level of long term accumulated doses of X-ray exposure of population. Inter-district differences in disease and mortality cancer run up to three times among people aged 60 and older. There are no statistically

  20. Retrospective epidemiological study of the X-Ray exposure

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, E. V.; Kalnitsky, S. A.; Shubic, V. M.

    2004-07-01

    There are a large amount of epidemiological studies nowadays in the world which are devoted to the analysis of the medical effects and the radiation risk. But a few of them deal with the analysis of the medical diagnostic radiation influence on health. It is appropriate, for the large compared contingent of the patients and the possibility of comparing them in several decades after the exposure are necessary for the evaluation of the influence of small doses on health. Meanwhile the X-ray exposure of the population is one of the most important types of radiation influence among all the kinds and sources of radiation. It is characterized by high dose rate and the possibility of multiple influence on a weakened and diseased organism. In connection with that, the eleven of the indices of population health was analyzed for the first time in Russia. The population was influenced by different levels of X-ray exposure 10-50 years ago. The research was carried out in the two groups of the Tumen (Siberia) regions. These regions are more or less equal in the climatic; ecologic, social-economic and demographic conditions. Nevertheless, they are different even only in the value of accumulated doses of X-ray exposure of the population (mostly in 50-70s) more than three times. Disease and mortality cancer of population of the last ten years in the regions were analyzed. The regions were selected taking into account the absence of the influence of other possible negative environmental factors. The data are found as the result of the dosimetric and epidemiological studies, and the processing of the archive statistic information. These researches demonstrated that on the whole there is the considerable statistically proved rise of disease cancer in the regions with high level of long term accumulated doses of X-ray exposure of population. Inter-district differences in disease and mortality cancer run up to three times among people aged 60 and older. There are no statistically

  1. 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)

  2. X-rays and magnetism: a review of program in magnetic studies with polarized soft x-rays

    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.

  3. An angle-dependent estimation of CT x-ray spectrum from rotational transmission measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yuan, E-mail: yuan.lin@duke.edu; Samei, Ehsan [Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Physics Department, Duke University, Durham, North Carolina 27708 (United States); Ramirez-Giraldo, Juan Carlos [Siemens Medical Solutions, Malvern, Pennsylvania 19355 (United States); Gauthier, Daniel J. [Physics Department, Duke University, Durham, North Carolina 27708 (United States); Stierstorfer, Karl [Siemens Healthcare, Forchheim 91301 (Germany)

    2014-06-15

    Purpose: Computed tomography (CT) performance as well as dose and image quality is directly affected by the x-ray spectrum. However, the current assessment approaches of the CT x-ray spectrum require costly measurement equipment and complicated operational procedures, and are often limited to the spectrum corresponding to the center of rotation. In order to address these limitations, the authors propose an angle-dependent estimation technique, where the incident spectra across a wide range of angular trajectories can be estimated accurately with only a single phantom and a single axial scan in the absence of the knowledge of the bowtie filter. Methods: The proposed technique uses a uniform cylindrical phantom, made of ultra-high-molecular-weight polyethylene and positioned in an off-centered geometry. The projection data acquired with an axial scan have a twofold purpose. First, they serve as a reflection of the transmission measurements across different angular trajectories. Second, they are used to reconstruct the cross sectional image of the phantom, which is then utilized to compute the intersection length of each transmission measurement. With each CT detector element recording a range of transmission measurements for a single angular trajectory, the spectrum is estimated for that trajectory. A data conditioning procedure is used to combine information from hundreds of collected transmission measurements to accelerate the estimation speed, to reduce noise, and to improve estimation stability. The proposed spectral estimation technique was validated experimentally using a clinical scanner (Somatom Definition Flash, Siemens Healthcare, Germany) with spectra provided by the manufacturer serving as the comparison standard. Results obtained with the proposed technique were compared against those obtained from a second conventional transmission measurement technique with two materials (i.e., Cu and Al). After validation, the proposed technique was applied to measure

  4. 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...

  5. Flash X Ray: A Diagnostic Tool for Shaped Charge Studies

    Directory of Open Access Journals (Sweden)

    S. G. Tatake

    1992-10-01

    Full Text Available At present many antitank weapon systems are employing shaped charge warheads. It is, therefore, extremely important for a designer to avail of the methods capable of predicting performance of shaped charges, mainly to achieve maximum penetration. For this purpose, it is necessary to study the behaviour of the shaped charge during actual firing tests. These tests are difficult because of high speed of events that take place, production of intense light, smoke, debris, etc, and the large scale destruction caused. To overcome these difficulties, flash x-ray system during the jet studies on 30, 60 and 90 mm shaped charges and the evaluation of jet characteristics parameters.

  6. Studies of some alloys using x-ray fluorescence

    International Nuclear Information System (INIS)

    In this project an attempt has been made for the study of alloys commonly used using x-ray fluorescence ( XRF ) technique. The alloys selected for the study included gold jewellery, steels, brasses and coins. The XRF method proved to be simple, fast, non-destructive and reliable as compared to chemical methods. The results showed that most of the gold jewellery used in this country have carat value of 18 and 21. Also most coins used in different countries are alloys of Cu and Ni. A simple spark method was used for the determination of C in steels, since C is not possible to analyze by XRF. ( Author )

  7. Use of intermediate focus for grazing incidence small and wide angle x-ray scattering experiments at the beamline P03 of PETRA III, DESY

    Energy Technology Data Exchange (ETDEWEB)

    Santoro, G.; Buffet, A.; Döhrmann, R.; Yu, S.; Roth, S. V. [Photon Science, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, D-22607 Hamburg (Germany); Körstgens, V.; Müller-Buschbaum, P. [Physik-Department, Technische Universität München, Lehrstuhl für Funktionelle Materialien, James-Franck-Str. 1, D-85748 Garching (Germany); Gedde, U.; Hedenqvist, M. [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Fibre and Polymer Technology, SE-10044 Stockholm (Sweden)

    2014-04-15

    We describe the new experimental possibilities of the micro- and nanofocus X-ray scattering beamline P03 of the synchrotron source PETRA III at DESY, Hamburg (Germany), which arise from experiments with smaller beam sizes in the micrometer range. This beamline has been upgraded recently to perform new kinds of experiments. The use of an intermediate focus allows for reducing the beam size of microfocused hard X-rays while preserving a large working distance between the focusing elements and the focus position. For the first time, this well-known methodology has been employed to grazing incidence small- and wide-angle X-ray scattering (GISAXS/GIWAXS). As examples, we highlight the applications to in situ studies using microfluidic devices in GISAXS geometry as well as the investigation of the crystallinity of thin films in GIWAXS geometry.

  8. 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.)

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Ultrafast X-ray Studies of Structural Dynamics at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Gaffney, K.J.; Lindenberg, A.M.; /SLAC, SSRL; Larsson, J.; /Lund Inst. Tech.; Sokolowski-Tinten, K.; /Jena U. /Duisburg U.; Blome, C.; /DESY; Synnergren, O.; /Lund Inst.; Sheppard, J.; /Oxford U.; Reis, D.A.; /Michigan U.; Hastings, J.B.; /SLAC, SSRL

    2005-09-30

    The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements demonstrate that the initial stage of crystal disordering results from inertial motion on a laser softened potential energy surface. These inertial dynamics dominate for the first half picosecond following laser excitation, indicating that interatomic forces minimally influence atomic excursions from the equilibrium lattice positions, even for motions in excess of an {angstrom}. This also indicates that the atoms disorder initially without losing memory of their lattice reference.

  14. Recent highlights in the X-ray study of blazars

    CERN Document Server

    Pian, E

    2002-01-01

    Blazars exhibit flux and spectral variations of largest amplitude at the highest frequencies. Therefore, monitoring their variability at X- and gamma-rays is the most effective tool to peer into the mighty powerhouse of these sources. High energy observations of the brightest blazars with the latest generation of satellites have allowed a detailed study of their behavior and have critically improved our understanding of the physics of blazar jets. I will review some of the recent results of blazar multiwavelength monitoring with emphasis on the X-ray campaigns accomplished with BeppoSAX and I will describe some of the future programs for blazar investigation from space, particularly with INTEGRAL.

  15. X-ray crystal spectroscopy of JET - a design study

    International Nuclear Information System (INIS)

    This study describes the design and specification of a diagnostic system to measure the space- and time-resolved x-ray spectrum from JET discharges with high-resolution crystal spectrometers operating in the wavelength region 1 - 15A. The specification is given in terms of sensitivity, resolving power, detector, and data handling requirements, special attention being given to the problems encountered in interfacing the spectrometer arrays to the torus vacuum system and in their disposition to the machine. Shielding requirements during the active mode are evaluated and a staged diagnostic is proposed to accommodate D - T operation. (U.K.)

  16. High-resolution soft X-ray beamline ADRESS at the Swiss Light Source for resonant inelastic X-ray scattering and angle-resolved photoelectron spectroscopies.

    Science.gov (United States)

    Strocov, V N; Schmitt, T; Flechsig, U; Schmidt, T; Imhof, A; Chen, Q; Raabe, J; Betemps, R; Zimoch, D; Krempasky, J; Wang, X; Grioni, M; Piazzalunga, A; Patthey, L

    2010-09-01

    The concepts and technical realisation of the high-resolution soft X-ray beamline ADRESS operating in the energy range from 300 to 1600 eV and intended for resonant inelastic X-ray scattering (RIXS) and angle-resolved photoelectron spectroscopy (ARPES) are described. The photon source is an undulator of novel fixed-gap design where longitudinal movement of permanent magnetic arrays controls not only the light polarization (including circular and 0-180 degrees rotatable linear polarizations) but also the energy without changing the gap. The beamline optics is based on the well established scheme of plane-grating monochromator operating in collimated light. The ultimate resolving power E/DeltaE is above 33000 at 1 keV photon energy. The choice of blazed versus lamellar gratings and optimization of their profile parameters is described. Owing to glancing angles on the mirrors as well as optimized groove densities and profiles of the gratings, the beamline is capable of delivering high photon flux up to 1 x 10(13) photons s(-1) (0.01% BW)(-1) at 1 keV. Ellipsoidal refocusing optics used for the RIXS endstation demagnifies the vertical spot size down to 4 microm, which allows slitless operation and thus maximal transmission of the high-resolution RIXS spectrometer delivering E/DeltaE > 11000 at 1 keV photon energy. Apart from the beamline optics, an overview of the control system is given, the diagnostics and software tools are described, and strategies used for the optical alignment are discussed. An introduction to the concepts and instrumental realisation of the ARPES and RIXS endstations is given. PMID:20724785

  17. An X-ray and optical study of the ultracompact X-ray binary A 1246-58

    NARCIS (Netherlands)

    in 't Zand, J. J. M.; Bassa, C. G.; Keek, L.; Verbunt, F.; Mendez, M.; Markwardt, C. B.; Jonker, P.G.

    2008-01-01

    Results are discussed of an X-ray and optical observation campaign of the low-mass X-ray binary A 1246-58 performed with instruments on Satellite per Astronomia X ("BeppoSAX"), the Rossi X-ray Timing Explorer (RXTE), the X-ray Multi-mirror Mission ("XMM-Newton"), the Swift mission, and the Very Larg

  18. An X-ray and optical study of the ultracompact X-ray binary A1246-58

    NARCIS (Netherlands)

    Zand, J. J. M. in 't

    2008-01-01

    Results are discussed of an X-ray and optical observation campaign of the low-mass X-ray binary A 1246-58 performed with instruments on Satellite per Astronomia X (’BeppoSAX’), the Rossi X-ray Timing Explorer (RXTE), the X-ray Multi-mirror Mission (’XMM-Newton’), the Swift mission, and the Very Larg

  19. Sidewall passivation layer thickness and composition profiles of etched silicon patterns from angle resolved x-ray photoelectron spectroscopy analysis

    Energy Technology Data Exchange (ETDEWEB)

    Haass, Moritz; Darnon, Maxime; Joubert, Olivier [CNRS/UJF-Grenoble1/CEA LTM, 17 avenue des Martyrs, 38054 Grenoble cedex 9 (France)

    2012-06-15

    In this study, we present a technique to analyze side wall passivation layers formed on silicon sidewalls after plasma processing. The thickness and chemical composition are derived from angle resolved x-ray photoelectron spectroscopy analyses. It is a non-destructive, quasi in situ method to determine profiles of the thickness and the chemical composition of passivation layers in trenches up to an aspect ratio of about 3. The performance of this technique to quantify the passivation layer thickness is compared to a standard technique using secondary electron microscopy images with respect to two different samples and is found to be at least equivalent. The possible uncertainties and limitations of this technique are discussed as well.

  20. Characterization of thin-film multilayers using magnetization curves and modeling of low-angle X-ray diffraction data

    Energy Technology Data Exchange (ETDEWEB)

    Lane, M. [Emory & Henry College, VA (United States); Chaiken, A.; Michel, R.P. [Lawrence Livermore National Lab., CA (United States)

    1994-12-01

    We have characterized thin-film multilayers grown by ion-beam sputtering using magnetization curves and modeling of low-angle x-ray diffraction data. In our films, we use ferromagnetic layer = Co, Fe, and NiFe and spacer layer = Si, Ge, FeSi{sub 2}, and CoSi{sub 2}. We have studied the effects of (1) deposition conditions; (2) thickness of layers; (3) different layer materials; and (4) annealing. We find higher magnetization in films grown at 1000V rather than 500V and in films with spacer layers of 50{angstrom} rather than 100{angstrom}. We find higher coercivity in films with cobalt grown on germanium rather than silicon, metal grown on gold underlayers rather than on glass substrates, and when using thinner spacer layers. Finally, modeling reveals that films grown with disilicide layers are more thermally stable than films grown with silicon spacer layers.

  1. Soft X-ray angle-resolved photoemission spectroscopy of heavily boron-doped superconducting diamond films

    Directory of Open Access Journals (Sweden)

    T. Yokoya, T. Nakamura, T. Matushita, T. Muro, H. Okazaki, M. Arita, K. Shimada, H. Namatame, M. Taniguchi, Y. Takano, M. Nagao, T. Takenouchi, H. Kawarada and T. Oguchi

    2006-01-01

    Full Text Available We have performed soft X-ray angle-resolved photoemission spectroscopy (SXARPES of microwave plasma-assisted chemical vapor deposition diamond films with different B concentrations in order to study the origin of the metallic behavior of superconducting diamond. SXARPES results clearly show valence band dispersions with a bandwidth of ~23 eV and with a top of the valence band at gamma point in the Brillouin zone, which are consistent with the calculated valence band dispersions of pure diamond. Boron concentration-dependent band dispersions near the Fermi level (EF exhibit a systematic shift of EF, indicating depopulation of electrons due to hole doping. These SXARPES results indicate that diamond bands retain for heavy boron doping and holes in the diamond band are responsible for the metallic states leading to superconductivity at low temperature. A high-resolution photoemission spectroscopy spectrum near EF of a heavily boron-doped diamond superconductor is also presented.

  2. 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.

  3. Critical-angle x-ray transmission grating spectrometer with extended bandpass and resolving power > 10,000

    OpenAIRE

    Heilmann, Ralf K.; Bruccoleri, Alexander R.; Kolodziejczak, Jeffery; Gaskin, Jessica A.; O'Dell, Stephen L.; Bhatia, Ritwik; Schattenburg, Mark L.

    2016-01-01

    Several high priority subjects in astrophysics can be addressed by a state-of-the-art soft x-ray grating spectrometer (XGS). An Explorer-scale, large-area (> 1,000 cm2), high resolving power (R > 3,000) XGS is highly feasible based on Critical-Angle Transmission (CAT) gratings, even for telescopes with angular resolution of 5-10 arcsec. Significantly higher performance can be provided by a CAT XGS on an X-ray-Surveyor-type mission. CAT gratings combine the advantages of blazed reflection grat...

  4. 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.

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

    International Nuclear Information System (INIS)

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

  7. An efficient photoelectric X-ray polarimeter for the study of black holes and neutron stars.

    Science.gov (United States)

    Costa, E; Soffitta, P; Bellazzini, R; Brez, A; Lumb, N; Spandre, G

    2001-06-01

    The study of astronomical objects using electromagnetic radiation involves four basic observational approaches: imaging, spectroscopy, photometry (accurate counting of the photons received) and polarimetry (measurement of the polarizations of the observed photons). In contrast to observations at other wavelengths, a lack of sensitivity has prevented X-ray astronomy from making use of polarimetry. Yet such a technique could provide a direct picture of the state of matter in extreme magnetic and gravitational fields, and has the potential to resolve the internal structures of compact sources that would otherwise remain inaccessible, even to X-ray interferometry. In binary pulsars, for example, we could directly 'see' the rotation of the magnetic field and determine if the emission is in the form of a 'fan' or a 'pencil' beam. Also, observation of the characteristic twisting of the polarization angle in other compact sources would reveal the presence of a black hole. Here we report the development of an instrument that makes X-ray polarimetry possible. The factor of 100 improvement in sensitivity that we have achieved will allow direct exploration of the most dramatic objects of the X-ray sky.

  8. Structural studies using X-ray absorption and scattering techniques

    International Nuclear Information System (INIS)

    The thesis presents extended X-ray absorption fine structure, EXAFS, and large angle X-ray scattering, LAXS, techniques; instrumentation, data collection and reduction, and applications. These techniques have been used to determine the structures of magnesium halides and organomagnesium halides in diethyl ether and tetrahydrofuran solution. The iodides were used for the LAXS measurements and Br K edge EXAFS data were collected for the corresponding bromides. Two different complexes are present in the diethyl ether solution of magnesium iodide; a polymeric chain-type structure where magnesium is tetrahedrally coordinated, as well as dimeric complex with octahedrally coordinated magnesium. Solvated MgI+ is the dominating species in tetrahydrofuran solution. The organomagnesium halides are present in diethyl ether solution as both solvated monomeric and dimeric complexes. Magnesium coordinates a halide ion, an alkyl or aryl group and four solvent molecules octahedrally in the monomeric complex. In the dimeric complex magnesium is octahedrally coordinated by two bridging halide ions, an alkyl or aryl group and three solvent molecules. The distribution of monomeric and dimeric complexes in various solutions are given by a dimerisation constant, Kdl. The results indicate that the Schlenk equilibrium is present in these solutions, however, in an extended form. In diethyl ether solution, where MgX2 does not dissociate, no MgX2 complex and thereby no Schlenk equilibrium has been observed. In tetrahydrofuran solution MgI2 has dissociated into mainly MgI+ and I-. This indicates that the concentration of MgI2 is low and that the Schlenk equilibrium should be expanded even further to include the dissociation equilibrium of the magnesium halide. In the thesis Fe K edge EXAFS data collected for the semireduced form of protein A of methane monooxygenase from Methylococcus capsulatus, are also presented. (139 refs.)

  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. 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.

  10. 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

  11. Surface and subsurface oxidation of Mo2C/Mo(100): low-energy ion-scattering, auger electron, angle-resolved X-ray photoelectron, and mass spectroscopy studies.

    Science.gov (United States)

    Ovári, László; Kiss, János; Farkas, Arnold P; Solymosi, Frigyes

    2005-03-17

    The interaction of oxygen with a carburized Mo(100) surface was investigated at different temperatures (300-1000 K). The different information depths of low-energy ion-scattering (LEIS) spectroscopy, with topmost layer sensitivity, Auger electron spectroscopy (AES), and angle-resolved X-ray photoelectron spectroscopy (ARXPS) allowed us to discriminate between reactions on the topmost layer and subsurface transformations. According to ARXPS measurements, a carbide overlayer was prepared by the high-temperature decomposition of C(2)H(4) on Mo(100), and the carbon distribution proved to be homogeneous with a Mo(2)C stoichiometry down to the information depth of XPS. O(2) adsorbs dissociatively on the carbide layer at room temperature. One part of the chemisorbed oxygen is bound to both C and Mo sites, indicated by LEIS. Another fraction of oxygen atoms probably resides in the hollow sites not occupied by C. The removal of C from the outermost layer by O(2), in the form of CO, detected by mass spectroscopy (MS), was observed at 500-600 K. The carbon-depleted first layer is able to adsorb more oxygen compared to the Mo(2)C/Mo(100) surface. Applying higher doses of O(2) at 800 K results in the inward diffusion of O and the partial oxidation of Mo atoms. This process, however, is not accompanied by the removal of C from subsurface sites. The depletion of C from the bulk starts only at 900 K (as shown by MS, AES, and XPS), very probably by the diffusion of C to the surface followed by its reaction with oxygen. At T(ads) = 1000 K, the carbon content of the sample, down to the information depth of XPS, decreased further, accompanied by the attenuation of the C concentration gradient and a substantially decreased amount of oxygen.

  12. 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

  13. An application of the grazing-angle incidence hard x-ray optical nanoscope in ultra-high density digital data read-out device

    Science.gov (United States)

    Bezirganyan, Hakob P.; Bezirganyan, Siranush E.; Bezirganyan, Petros H., Jr.; Bezirganyan, Hayk H., Jr.

    2008-08-01

    We present in this theoretical paper a set-up of grazing-angle incidence hard x-ray nanoscope (GIXN), which is the essential part of ultra-high density digital data read-out device. The GIXN consists of the asymmetrically cut single crystal, which is operating like an image magnifier. The X-ray high-resolution diffractive optical lens (zone plate) and spatially resolving detector (CCD camera) are arranged like in classical schemes of the X-ray imaging microscopy. Proposed nanoscope operates based on grazing-angle incidence x-ray backscattering diffraction (GIXB) technique applied in the specular beam suppression mode. Grazing-angle incident X-ray configuration allows the handling of data from very large surface area of the X-ray optical memory disk (X-ROM) and, consequently, the data read-out speed is much faster than in optical data read-out systems.

  14. A high-field pulsed magnet system for x-ray scattering studies in Voigt geometry

    CERN Document Server

    Islam, Zahirul; Ruff, Jacob P C; Das, Ritesh K; Trakhtenberg, Emil; Nojiri, Hiroyuki; Narumi, Yasuo; Canfield, Paul C

    2011-01-01

    We present a new pulsed-magnet system that enables x-ray single-crystal diffraction in addition to powder and spectroscopic studies in Voigt geometry. The apparatus consists of a large-bore solenoid, cooled by liquid nitrogen. A second independent closed-cycle cryostat is used for cooling samples near liquid helium temperatures. Pulsed magnetic fields up to ~30 T with a minimum of ~6 ms in total duration are generated by discharging a 40 kJ capacitor bank into the magnet coil. The unique characteristic of this instrument is the preservation of maximum scattering angle (~23.6 deg.) through the magnet bore by virtue of a novel double-funnel insert. This instrument would facilitate x-ray diffraction and spectroscopic studies that are impractical, if not impossible, to perform using conventional split-pair magnets and offers a practical solution for preserving optical access in future higher-field pulsed magnets.

  15. X-ray studies of nanoporous carbon powders produced from silicon carbide

    International Nuclear Information System (INIS)

    X-ray diffraction, small-angle X-ray scattering, and X-ray photoelectron spectroscopy were used to study the structure of nanoporous carbon powders produced directly by chlorination of polycrystalline α-SiC powders with various degrees of dispersion. Small-angle scattering data were used to derive the distribution function for scattering inhomogeneities with respect to inertia radii m(Rg). It is shown that the mean sizes and the fraction of large inhomogeneities increase with increasing size of grains in the starting powder. As follows from the diffraction patterns, the degree of 'graphitization' of nanocluster structure increases simultaneously, which is attributed to longer times required for carbonization of coarser grains. An analysis of photoelectron spectra for 1s electrons of carbon atoms shows that, for most of the C-C bonds (>65%), the hybridization of valence bonds is intermediate between those for graphite and diamond (spx, where 2 < x < 3), which is indicative of the bending of graphene-like layers in nanoclusters

  16. Temporal Studies of Supergiant Fast X-ray Transients

    CERN Document Server

    Drave, S P; Clark, D J; McBride, V A; Hill, A B; Sguera, V; Scaringi, S; Bazzano, A; Townsend, L J

    2011-01-01

    SFXTs are a new class of HMXB unveiled by INTEGRAL. They are extreme systems characterised by very short outbursts (a few hours) and extreme X-ray luminosity dynamic ranges (~10^{4}). Ten confirmed systems are currently known and have shown parallels with both Sg-XRBs and Be-XRBs. Temporal studies across all timescales are key to understanding both the place of SFXTs within the HMXB hierarchy and the accretion mechanisms at work within the objects. Here we present the discovery of a new 51.47 \\pm 0.02 day orbital period in the SFXT XTE J1739$-$302 using INTEGRAL observations. We also present a higher time resolution study of the SFXTs SAX J1818.6-1703, IGR J16479-4514 and IGR J16465-4507 using RXTE that shows newly discovered flaring activity.

  17. Glancing angle Talbot-Lau grating interferometers for phase contrast imaging at high x-ray energy

    Science.gov (United States)

    Stutman, D.; Finkenthal, M.

    2012-08-01

    A Talbot-Lau interferometer is demonstrated using micro-periodic gratings inclined at a glancing angle along the light propagation direction. Due to the increase in the effective thickness of the absorption gratings, the device enables differential phase contrast imaging at high x-ray energy, with improved fringe visibility (contrast). For instance, at 28° glancing angle, we obtain up to ˜35% overall interferometer contrast with a spectrum having ˜43 keV mean energy, suitable for medical applications. In addition, glancing angle interferometers could provide high contrast at energies above 100 keV, enabling industrial and security applications of phase contrast imaging.

  18. Probabilistic Evaluation of Three-Dimensional Reconstructions from X-Ray Images Spanning a Limited Angle

    Directory of Open Access Journals (Sweden)

    Jörn Ostermann

    2012-12-01

    Full Text Available An important part of computed tomography is the calculation of a three-dimensional reconstruction of an object from series of X-ray images. Unfortunately, some applications do not provide sufficient X-ray images. Then, the reconstructed objects no longer truly represent the original. Inside of the volumes, the accuracy seems to vary unpredictably. In this paper, we introduce a novel method to evaluate any reconstruction, voxel by voxel. The evaluation is based on a sophisticated probabilistic handling of the measured X-rays, as well as the inclusion of a priori knowledge about the materials that the object receiving the X-ray examination consists of. For each voxel, the proposed method outputs a numerical value that represents the probability of existence of a predefined material at the position of the voxel while doing X-ray. Such a probabilistic quality measure was lacking so far. In our experiment, false reconstructed areas get detected by their low probability. In exact reconstructed areas, a high probability predominates. Receiver Operating Characteristics not only confirm the reliability of our quality measure but also demonstrate that existing methods are less suitable for evaluating a reconstruction.

  19. Biological dosimetry of X-rays by micronuclei study

    International Nuclear Information System (INIS)

    Biological dosimetry consists of estimating absorbed doses for people exposed to radiation by mean biological methods. Several indicators used are based in hematological, biochemical an cytogenetics data, although nowadays without doubt, the cytogenetic method is considered to be the most reliable, in this case, the study of micronuclei in peripheral blood lymphocytes cytokinetic blocked can be related to absorbed dose through an experimental calibration curve. An experimental dose-response curve, using micronuclei assay for X-rays at 250 kVp, 43,79 rads/min and temperature 37 degree celsius has been produced. Experimental data is fitted to model Y=c+ α D+β D2 where. Y is the number micronuclei per cell and D the dose. the curve is compared with those produced elsewhere

  20. X-ray photoemission spectroscopy study of hexavalent uranium compounds

    International Nuclear Information System (INIS)

    The electronic structure of the outer occupied levels of a series of hexavalent uranium (predominately uranyl) compounds was studied using x-ray photoemission spectroscopy (XPS). The changes in the spectral features of the outer occupied levels with the variation of the uranium-oxygen bond lengths (1.7--2.1 A) are systematically investigated. Previously unexplained spectral structure has been found to result from ligand-field splitting of the occupied U 6p3/2 levels. The XPS results are compared with predictions of a relativistic molecular-cluster calculation and with the results of a simple point-charge crystal-field model. When the crystalline electric fields generated by both the primary and secondary ligands are taken into consideration, excellent quantitative agreement is obtained between the XPS data and the molecular-cluster results with no parameter adjustment

  1. Biological Dosimetry of X-rays by micronuclei study

    International Nuclear Information System (INIS)

    Biological dosimetry consists of estimating absorbed doses for people exposed to radiation by mean biological methods. Several indicators used are based in haematological, biochemical an cytogenetics data, although nowadays without doubt, the cytogenetic method is considered to be the most reliable, in this case, the study of micronuclei in peripheral blood lymphocytes citokinetics blocked can be related to absorbed dose through an experimental calibration curve. An experimental dose-response curve, using micronuclei assay for X-rays at 250 kVp, 43,79 rads/min and temperature 37 degree centigree has been produced. Experimental data is fitted to model Y=C+ αD+BD''2 where Y is the number of micronuclei per cell and D the dose. The curve is compared with those produced elsewhere. (Author) 24 refs

  2. High resolution energy-angle correlation measurement of hard x rays from laser-Thomson backscattering.

    Science.gov (United States)

    Jochmann, A; Irman, A; Bussmann, M; Couperus, J P; Cowan, T E; Debus, A D; Kuntzsch, M; Ledingham, K W D; Lehnert, U; Sauerbrey, R; Schlenvoigt, H P; Seipt, D; Stöhlker, Th; Thorn, D B; Trotsenko, S; Wagner, A; Schramm, U

    2013-09-13

    Thomson backscattering of intense laser pulses from relativistic electrons not only allows for the generation of bright x-ray pulses but also for the investigation of the complex particle dynamics at the interaction point. For this purpose a complete spectral characterization of a Thomson source powered by a compact linear electron accelerator is performed with unprecedented angular and energy resolution. A rigorous statistical analysis comparing experimental data to 3D simulations enables, e.g., the extraction of the angular distribution of electrons with 1.5% accuracy and, in total, provides predictive capability for the future high brightness hard x-ray source PHOENIX (photon electron collider for narrow bandwidth intense x rays) and potential gamma-ray sources.

  3. 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.

  4. 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

  5. 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.

  6. Co/Mo2C mirror as studied by x-ray fluorescence and photoelectron spectroscopies induced by x-ray standing waves

    Science.gov (United States)

    Jonnard, P.; Le Guen, K.; Yuan, Y. Y.; André, J.-M.; Mukherjee, S.; Giglia, A.; Nannarone, S.; Mahne, N.; Wang, Z.-S.; Li, H.-C.; Zhu, J.-T.

    2012-12-01

    We study a periodic Co/Mo2C multilayer prepared by magnetron sputtering. The period is 4.1 nm and the sample is designed to work around 778 eV, i.e. close to the Co 2p3/2 threshold, at a glancing angle of 11°. In this condition, strong x-ray standing waves set up within the sample. In order to probe different depths within the stack, particularly the interfaces, the glancing angle is moved along the first Bragg peak, while, the B 1s, C 1s, Mo 3d or O 1s photoelectron spectra, the Co Lα x-ray spectrum as well as the drain current of the sample are measured. Boron is present in the 3.5 nm B4C capping layer and oxygen is from surface contamination. The photoelectrons bring information from the superficial zone, i.e. the 5 first nm, while the characteristic x-rays probe the whole stack. Clear modulations of the intensity of the studied signals as well as core level shifts are observed when going through the Bragg peak. In order to understand what happens in the multilayer calculations of depth distributions of the electric field and the energy loss by the radiation are made with the IMD and OPAL codes, respectively. The combination of experimental results and theoretical simulations will enable us to determine from which place originate the various signals and to know if some interaction exists between the Co and Mo2C layers.

  7. High resolution X-ray diffraction studies on unirradiated and irradiated strontium hexaferrite crystals

    Indian Academy of Sciences (India)

    Balwinder Kaur; Monita Bhat; F Licci; Ravi Kumar; K K Bamzai; P N Kotru

    2012-04-01

    High-resolution X-ray diffraction technique, employing a three-crystal monochromator–collimator combination is used to study the irradiation induced defects in flux grown Sr-hexaferrite crystals irradiated with 50 MeV Li3+ ion beams at room temperature with a fluence value of 1 × 1014 ions/cm2. The diffraction curves of the irradiated crystals suggest the possibility of creation of low angle grain boundaries and other point/clusters of defects causing amorphization in the irradiated crystals. The perfection of the irradiated and unirradiated (0001) cleaved surfaces of the crystals is studied using the bulk method of X-ray topography. The topographs supplement the findings suggestive of modifications in the crystalline quality of SrFe12O19 on irradiation with SHI of Li3+. Etching of the (0001) cleaved surfaces in H3PO4 at 120°C suggests that the dissolution characteristics of the surfaces get affected on irradiation with SHI of Li3+, besides supporting the findings of HRXRD and X-ray topography regarding modifications in the perfection of SrFe12O19 on irradiation.

  8. X-ray exposure in utero and school performance: a population-based study of X-ray pelvimetry

    International Nuclear Information System (INIS)

    Aim: To investigate the association between exposure to ionising radiation from pelvimetric examinations in utero and school performance. Material and methods: This was a population-based cohort study comprising 46,066 children born in the county of Östergötland, Sweden, from 1980 through 1990. Through record linkage between Swedish registers, children exposed in utero to X-ray pelvimetry examination were compared to other children born in the same county during the study period, as well as to their unexposed siblings. Outcome variable was primary school grades, expressed in centiles and calculated through linear regression. Results: In the univariate analysis, children exposed to X-ray pelvimetry in utero had higher school grades compared to unexposed children (point estimate 3 centiles, 95% confidence interval [CI]: 1.5 to 4.6). When sex, mother's education and income, birth order, and birth position were included in the analysis; however, the difference was reduced and the association was no longer statistically significant (PE 1.4, 95% CI: –0.1 to 2.8). Comparing exposed children with their siblings showed no statistical difference in univariate analysis or in multivariate analysis. Conclusion: No suggestion was found of a negative effect on school performance from in utero exposure of diagnostic X-ray pelvimetry. -- Highlights: •Pelvimetric examinations expose fetus to low levels of radiation. •No detectable effect on childrens final primary school grades from pelvimetric examinations. •Pelvimetric examinations is a safe procedure for the fetus regarding shool performance

  9. X-ray Diffraction Study of Molybdenum to 900 GPa

    Science.gov (United States)

    Wang, J.; Coppari, F.; Smith, R.; Eggert, J.; Boehly, T.; Collins, G. W.; Duffy, T. S.

    2013-12-01

    Molybdenum (Mo) is a transition metal that is important as a high-pressure standard. Its equation of state, structure, and melting behavior have been explored extensively in both experimental and theoretical studies. Melting data up to the Mbar pressure region from static compression experiments in the diamond anvil cell [Errandonea et al. 2004] are inconsistent with shock wave sound velocity measurements [Hixson et al., 1989]. There are also conflicting reports as to whether body-centered cubic (BCC) Mo transforms to a face-centered cubic (FCC), hexagonal close packed (HCP) or double hexagonal close packed (DHCP) structure at either high pressure or high pressure and temperature conditions [Belonoshko et al. 2008, Mikhaylushkin et al., 2008 and Cazorla et al., 2008]. Recently, a phase transition from BCC to the DHCP phase at 660 GPa and 0 K was predicted using the particle swam optimization (PSO) method (Wang et al, 2013). Here we report an x-ray diffraction study of dynamically compressed molybdenum. Experiments were conducted using the Omega laser at the Laboratory for Laser Energetics at the University of Rochester. Mo targets were either ramp or shock compressed using a laser drive. In ramp loading, the sample is compressed sufficiently slowly that a shock wave does not form. This results in lower temperatures, keeping the sample in the solid state to higher pressures. X-ray diffraction measurements were performed using quasi-monochromatic x-rays from a highly ionized He-α Cu source and image plate detectors. Upon ramp compression, we found no evidence of phase transition in solid Mo up to 900 GPa. The observed peaks can be assigned to the (110) and (200) or (220) reflections of BCC Mo up to the highest pressure, indicating that Mo does not melt under ramp loading to maximum pressure reached. Under shock loading, we did not observe any evidence for the solid-solid phase transformation around 210 GPa as reported in previous work (Hixson et al, 1989). The BCC

  10. 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...

  11. 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

  12. X-ray and SEM studies on zirconia powders

    Directory of Open Access Journals (Sweden)

    L. Pająk

    2008-12-01

    Full Text Available Purpose: The microstructure characterization of commercially available zirconia powders was the purpose of this paper. Different methods of structure analysis were applied owing to the complex, multiphase structure of studied materials.Design/methodology/approach: The X-ray diffraction (XRD and scanning electron microscopy (SEM investigations were performed on three commercial zirconia ceramic materials: Amdry 204 NS (ZrO2  8 wt.% of Y2O3, Metco C8  YZ (ZrO2  8 wt.% of Y2O3 and Metco 202 (ZrO2  20 wt.% of Y2O3. The Rietveld method appeared to be very useful in the verification of the qualitative phase composition and in the determination of phase abundance. Hill and Howard procedure was applied for quantitative phase analysis. The parameters of the individual diffraction line profiles were determined by PRO-FIT Toraya procedure. The powder morphology was analyzed by SEM method.Findings: In the Amdry sample comparable contents of two phases: monoclinic (44.1 wt.% and cubic (55.9 wt.% was stated by XRD analysis. The presence of Y2O3 phase besides of monoclinic, tetragonal and cubic ZrO2 ones were stated for both Metco samples. The tetragonal phase (55.2 wt.% was found to be the main component of the Metco C8-YZ sample whereas the content of Y2O3 is the lowest (2.7 wt.%. On the other hand cubic phase (68.2 wt.% was the main component of the Metco 202 sample and the content of Y2O3 is again the lowest (4.5 wt.%. The SEM images of all the samples reveal the spherical shape of powder particles. The morphology of both Metco samples is quite similar. For Metco 202 sample the hierarchical type structure of powder particle is observed; the greater particles contain smaller ones. The shell of particles is composed of distinct patches. On the other hand the structure of spherical particles of Amdry sample is of branched, rather dense skeleton type. From X-ray diffraction data it can be concluded that the crystallite size of all involved phases

  13. 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

  14. 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.

  15. 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.

  16. DETERMINATION OF DEGREE OF CRYSTALLINITY OF NYLON 1212 BY WIDE-ANGLE X-RAY DIFFRACTION

    Institute of Scientific and Technical Information of China (English)

    Jian-bin Song; Min-qiao Ren; Qing-yong Chen; Shu-yun Wang; Qing-xiang Zhao; Hong-fang Zhang; Zhi-shen Mo

    2004-01-01

    Based on the X-ray scattering intensity theory and using the approximate expression for the atomic scattering factor, the correction factors for three crystalline peaks and an amorphous peak of Nylon 1212 were calculated and the formula of degree of crystallinity of Nylon 1212 was derived by a graphic multipeak resolution method. The degree of crystallinity calculated from the WAXD method is compatible with those obtained by density and calorimetry methods.

  17. An optical & X-ray study of the counterpart to the SMC X-ray binary pulsar system SXP327

    CERN Document Server

    Coe, M J; Corbet, R H D; Galache, J; McBride, V A; Townsend, L J; Udalski, A

    2008-01-01

    Optical and X-ray observations are presented here of a newly reported X-ray transient system in the Small Magellanic Cloud. The data reveal many previously unknown X-ray detections of this system and clear evidence for a 49.995d binary period. In addition, the optical photometry show recurring outburst features at the binary period which may well be indicative of the neutron star interacting with a circumstellar disk around a Be star.

  18. 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

  19. Preliminary Studies on X-Ray-sensitive Liposome

    Institute of Scientific and Technical Information of China (English)

    MENG Fan-xu; XU Hua-ping; QI Yan-fei; XU Kun; SONG Xiu-ling; NIU Shu; LI Juan

    2012-01-01

    The synthesis of a new type of X-ray-sensitive compound “di-(1-hydroxylundecyl)diselenide” and its application in the preparation of a new type of liposome with X-ray sensitivity was reported.This new liposome was synthesized to encapsulate doxorubicin hydrochloride(Dox),with its physical and chemical properties,stability,and radiation sensitivity determined.Based on the pH-gradient method,liposomal Dox was prepared via ultrasonic emulsification and then purified on a Sephadex G50 mini-column.UV spectrophotometry and liquid chromatography were used to detect the encapsulation efficiency and radiation sensitivity of the Dox-loaded liposome.The results show that through changes in release rate,this liposome shows a relative radiosensitivity.In terms of radiation sensitivity,the drug leak rate of the X-ray-sensitive Dox-loaded liposome increased gradually and peaked at 65.4% under the X-ray radiation of a dose of 10 Gy or more than 10 Gy,which is significantly different from that of ordinary liposomes.Meanwhile,X-ray-sensitive Dox-loaded liposome has a good dispersion stability,with an average particle size of approximate 120 nm.The efficiency of this liposome encapsulating Dox was 75.84%,slightly lower than that of ordinary liposomes.The X-ray-sensitive Dox-loaded liposome exhibited suspension stability within 30 d of storage at 4 ℃,without visible precipitation.Di-(1-hydroxylundecyl)diselenide is safe and noncytotoxic and compared with those of synthetic phospholipids its synthesis is low cost and does not require complex conditions.

  20. Combining operando synchrotron X-ray tomographic microscopy and scanning X-ray diffraction to study lithium ion batteries.

    Science.gov (United States)

    Pietsch, Patrick; Hess, Michael; Ludwig, Wolfgang; Eller, Jens; Wood, Vanessa

    2016-01-01

    We present an operando study of a lithium ion battery combining scanning X-ray diffraction (SXRD) and synchrotron radiation X-ray tomographic microscopy (SRXTM) simultaneously for the first time. This combination of techniques facilitates the investigation of dynamic processes in lithium ion batteries containing amorphous and/or weakly attenuating active materials. While amorphous materials pose a challenge for diffraction techniques, weakly attenuating material systems pose a challenge for attenuation-contrast tomography. Furthermore, combining SXRD and SRXTM can be used to correlate processes occurring at the atomic level in the crystal lattices of the active materials with those at the scale of electrode microstructure. To demonstrate the benefits of this approach, we investigate a silicon powder electrode in lithium metal half-cell configuration. Combining SXRD and SRXTM, we are able to (i) quantify the dissolution of the metallic lithium electrode and the expansion of the silicon electrode, (ii) better understand the formation of the Li15Si4 phase, and (iii) non-invasively probe kinetic limitations within the silicon electrode. A simple model based on the 1D diffusion equation allows us to qualitatively understand the observed kinetics and demonstrates why high-capacity electrodes are more prone to inhomogeneous lithiation reactions. PMID:27324109

  1. Combining operando synchrotron X-ray tomographic microscopy and scanning X-ray diffraction to study lithium ion batteries

    Science.gov (United States)

    Pietsch, Patrick; Hess, Michael; Ludwig, Wolfgang; Eller, Jens; Wood, Vanessa

    2016-01-01

    We present an operando study of a lithium ion battery combining scanning X-ray diffraction (SXRD) and synchrotron radiation X-ray tomographic microscopy (SRXTM) simultaneously for the first time. This combination of techniques facilitates the investigation of dynamic processes in lithium ion batteries containing amorphous and/or weakly attenuating active materials. While amorphous materials pose a challenge for diffraction techniques, weakly attenuating material systems pose a challenge for attenuation-contrast tomography. Furthermore, combining SXRD and SRXTM can be used to correlate processes occurring at the atomic level in the crystal lattices of the active materials with those at the scale of electrode microstructure. To demonstrate the benefits of this approach, we investigate a silicon powder electrode in lithium metal half-cell configuration. Combining SXRD and SRXTM, we are able to (i) quantify the dissolution of the metallic lithium electrode and the expansion of the silicon electrode, (ii) better understand the formation of the Li15Si4 phase, and (iii) non-invasively probe kinetic limitations within the silicon electrode. A simple model based on the 1D diffusion equation allows us to qualitatively understand the observed kinetics and demonstrates why high-capacity electrodes are more prone to inhomogeneous lithiation reactions. PMID:27324109

  2. X-ray diffraction study of synthetic tetraborates and hexaborates

    International Nuclear Information System (INIS)

    The results of the X-ray diffraction of the tetraborates (NH3CH2CH2NH3)(B4O5(OH)4), (NH4)(Co(NH3)5H2O)(B4O5(OH)4)2x5H2O and of the hexaborates Ni(H2O)4(B6O)(OH)6xH2O (triclinic and monoclinic modification). (NH4)2{Co(H2O)2(B6O7(OH)6)2}x2H2O, (Ni(H2O)6){Ni(B6O7(OH)3(OCH3)3)2}, Co(H2O)3(B6O7(OH)6)x1.5C2H5OH and Ni(H2O)3(B6O7(OH)6)xC2H5OH have been reviewed. The crystal solvates isostructural to the latter compound - nickel hexaborates containing propyl and allyl alcohols, acetone and methyl ethyl ketone have been studied

  3. Synchrotron X-Ray Radiation and Deformation Studies

    DEFF Research Database (Denmark)

    Fæster Nielsen, Søren

    machining. The conical slit has six 25µm thick conically shaped openings matching six of the Debye-Scherrer cones from a fcc powder. By combining the conical slit with a micro-focused incoming beam of hard X-rays an embedded gauge volume is defined. Using a 2D detector, fast and complete information can...... in combination with synchrotron X-ray tomography in order to gain new in-formation on the wetting kinetics of liquid gallium in aluminium grain boundaries. Finally, an electron microscopy investigation was carried out in order to describe the lattice rotations and texture evolution in uniaxially compressed...... aluminium single crystals and polycrystals....

  4. Observational studies of X-ray binary systems

    International Nuclear Information System (INIS)

    The subject of Chapter 1 is theoretical. The other chapters, Ch. 2 to 6, contain original observational data and efforts towards their interpretation. Of these, Ch. 3, 4 and 5 deal with massive X-ray binaries, Ch. 6 with low-mass systems and Ch. 2 with Cygnus X-3, which we have not yet been able to assign to any of these two classes. The X-ray observations described were made with the COS-B satellite. Work based on UV and optical observations is described in Ch. 5. The UV observations were made with the IUE satellite, the optical observations at several ground-based observatories. (Auth.)

  5. Application of X-ray CT to the study of microstructure and diffusivity in cementitious materials

    OpenAIRE

    Darma, Ivan Sandi

    2014-01-01

    At the beginning of its development, the X-ray CT technique originally was developed for medical analysis. However, along with the advances in technology, the ability of X-ray CT continues to increase. Therefore, the use of X-ray CT is no longer intended for medical application but has expanded to other fields such as civil engineering especially for material science. Related to construction materials, there are many experimental methods that can be used to study the microstructure of cementi...

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

    Science.gov (United States)

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

    2013-10-01

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

  7. X-ray source population study of the starburst galaxy M83 with XMM-Newton

    OpenAIRE

    Ducci, L.; Sasaki, M.; Haberl, F.; Pietsch, W.

    2013-01-01

    We present the results obtained from the analysis of three XMM-Newton observations of M83. The aims of the paper are studying the X-ray source populations in M83 and calculating the X-ray luminosity functions of X-ray binaries for different regions of the galaxy. We detected 189 sources in the XMM-Newton field of view in the energy range of 0.2-12 keV. We constrained their nature by means of spectral analysis, hardness ratios, studies of the X-ray variability, and cross-correlations with cata...

  8. 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

  9. 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.

  10. 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.

  11. 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)

  12. 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.

  13. 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.

  14. Interfacial structure of molecular beam epitaxial grown cubic-GaN films on GaAs(001) probed by x-ray gazing-angle specular reflection

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    We report on a study of interfacial structure of GaN films grown on GaAs(001) substrates by plasma-assisted molecular beam epitaxy using x-ray grazing-angle specular reflection.We show that interfacial layers with electron densities differing from those of GaN and GaAs were formed upon deposition of GaN.It is also found that the interfacial structure of our systems depends strongly on the course of the initial layer deposition.The phase purity of the GaN films was examined by x-ray reciprocal space mapping.A simple kinetic growth model suggested by our results has been presented.

  15. Pinhole X-ray Fluorescence Imaging of Gadolinium Nanoparticles: A Preliminary Monte Carlo Study

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Seong Moon; Sung, Won Mo; Ye, Sung Joon [Seoul National University, Seoul (Korea, Republic of)

    2014-10-15

    X-ray fluorescence imaging is a modality for the element-specific imaging of a subject through analysis of characteristic x-rays produced by exploiting the interaction of high atomic number elements and incoming x-rays. Previous studies have utilized a polychromatic x-ray source to investigate the production of in vivo x-ray fluorescence images for the assessment of concentrations and locations of gold nanoparticles. However, previous efforts have so far been unable to detect low concentrations, such as 0.001% gold by weight, which is an expected concentration accumulated in tumors. We examined the feasibility of a monochromatic synchrotron x-rays implementation of pinhole x-ray fluorescence imaging by Monte Carlo simulations using MCNP5. In the current study, gadolinium (Gd) nanoparticles, which have been widely used as a contrast agent in magnetic resonance imaging and also as a dose enhancer in radiation therapy, were chosen for tumor targeting. Since a monochromatic x-ray source is used, the increased x-ray fluorescence signals allow the detection of low concentrations of Gd. Two different monochromatic x-ray beam energies, 50.5 keV near the Kedge energy (i.e., 50.207 keV) of Gd and 55 keV, were compared by their respective imaging results. Using Monte Carlo simulations the feasibility of imaging low concentrations of Gd nanoparticles (e.g., 0.001 wt%) with x-ray fluorescence using monochromatic synchrotron x-rays of two different energies was shown. In the case of imaging a single Gd column inserted in the center of a water phantom, the fluorescence signals from 0.05 wt% and 0.1 wt% Gd columns irradiated with a 50.5 keV photon beam were higher than those irradiated with 55 keV. Below 0.05 wt% region no significant differences were found.

  16. Pinhole X-ray Fluorescence Imaging of Gadolinium Nanoparticles: A Preliminary Monte Carlo Study

    International Nuclear Information System (INIS)

    X-ray fluorescence imaging is a modality for the element-specific imaging of a subject through analysis of characteristic x-rays produced by exploiting the interaction of high atomic number elements and incoming x-rays. Previous studies have utilized a polychromatic x-ray source to investigate the production of in vivo x-ray fluorescence images for the assessment of concentrations and locations of gold nanoparticles. However, previous efforts have so far been unable to detect low concentrations, such as 0.001% gold by weight, which is an expected concentration accumulated in tumors. We examined the feasibility of a monochromatic synchrotron x-rays implementation of pinhole x-ray fluorescence imaging by Monte Carlo simulations using MCNP5. In the current study, gadolinium (Gd) nanoparticles, which have been widely used as a contrast agent in magnetic resonance imaging and also as a dose enhancer in radiation therapy, were chosen for tumor targeting. Since a monochromatic x-ray source is used, the increased x-ray fluorescence signals allow the detection of low concentrations of Gd. Two different monochromatic x-ray beam energies, 50.5 keV near the Kedge energy (i.e., 50.207 keV) of Gd and 55 keV, were compared by their respective imaging results. Using Monte Carlo simulations the feasibility of imaging low concentrations of Gd nanoparticles (e.g., 0.001 wt%) with x-ray fluorescence using monochromatic synchrotron x-rays of two different energies was shown. In the case of imaging a single Gd column inserted in the center of a water phantom, the fluorescence signals from 0.05 wt% and 0.1 wt% Gd columns irradiated with a 50.5 keV photon beam were higher than those irradiated with 55 keV. Below 0.05 wt% region no significant differences were found

  17. The geometry of radio-quiet AGN studied with X-ray polarimetry

    Science.gov (United States)

    Matt, Giorgio

    2016-07-01

    Our current X-ray view of AGN in the local Universe is based on spectroscopic, imaging and timing data. In this talk I will discuss the importance of adding the polarimetric view. The geometry of the matter around the black hole (from the X-ray emitting corona to more distant circumnuclear matter) can be probed by X-ray polarimetry. Observational perspectives in view of the X-ray polarimetric missions currently under study at NASA and ESA will be also discussed.

  18. 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

  19. Critical-angle x-ray transmission grating spectrometer with extended bandpass and resolving power > 10,000

    CERN Document Server

    Heilmann, Ralf K; Kolodziejczak, Jeffery; Gaskin, Jessica A; O'Dell, Stephen L; Bhatia, Ritwik; Schattenburg, Mark L

    2016-01-01

    Several high priority subjects in astrophysics can be addressed by a state-of-the-art soft x-ray grating spectrometer (XGS). An Explorer-scale, large-area (> 1,000 cm2), high resolving power (R > 3,000) XGS is highly feasible based on Critical-Angle Transmission (CAT) gratings, even for telescopes with angular resolution of 5-10 arcsec. Significantly higher performance can be provided by a CAT XGS on an X-ray-Surveyor-type mission. CAT gratings combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of transmission gratings (low mass, relaxed alignment and temperature requirements, transparent at high energies) with minimal mission resource demands. They are high-efficiency blazed transmission gratings that consist of freestanding, ultra-high aspect-ratio grating bars made from SOI wafers using anisotropic dry and wet etch techniques. Blazing is achieved through reflection off grating bar sidewalls. Silicon is well matched to the soft x-ray band, and...

  20. X-ray diffraction study of directionally grown perylene crystallites

    DEFF Research Database (Denmark)

    Breiby, Dag W.; Lemke, H. T.; Hammershøj, P.;

    2008-01-01

    Using grazing incidence X-ray diffraction, perylene crystallites grown on thin highly oriented poly(tetrafluoroethylene) (PTFE) films on silicon substrates have been investigated. All the perylene crystallites are found to orient with the ab plane of the monoclinic unit cell parallel...

  1. X-ray scattering studies of lanthanides magnetism

    DEFF Research Database (Denmark)

    McMorrow, D.; Bohr, Jakob; Gibbs, D.

    1999-01-01

    Interest in the applications of X-ray synchrotron radiation has grown rapidly during the last decade. At the present time, intense, ultra-bright synchrotron radiation is available on a routine basis from third-generation sources located in Europe (ESRF), North America (APS) and Japan (Spring8). T...

  2. X-ray fractography studies on austenitic stainless steels

    NARCIS (Netherlands)

    Rajanna, K.; Pathiraj, B.; Kolster, B.H.

    1996-01-01

    In this investigation, the fracture surfaces of SS 304 and SS 316 austenitic steels were analysed using the X-ray fractography technique. In both cases, a decrease in the austenite content was observed at the fracture surface as a result of deformation induced martensite, indicating a linear relatio

  3. X-RAY DIFFRACTION STUDY OF A PANCHAVAKTRA RAS

    Directory of Open Access Journals (Sweden)

    B. Srinivasulu*, P. Bhadra Dev, P.H.C. Murthy

    2012-06-01

    Full Text Available Analytical monitoring of Pharmaceutical products is necessary to ensure its safety and efficacy throughout all phases of the drug. A systematic approach should be adapted to the presentation and evaluation of stable information, which should include, as necessary, physical, chemical, biological and microbiological test characteristics. Indian System of Medicine (ISM frequently uses metal/mineral drugs. It is mandatory to standardize the preparatory procedures. For the Pharmaceutical standardization, three batches of the Panchavaktra ras were prepared and analytical study of final product carried out. Panchavaktra ras consist equal parts of Parada (Mercury, Gandhaka (Sulphur, Tankana (Borax Pippali (Piper longum L. and Marica (Piper nigrum L., and Mardhana (Grinding was done carefully with sufficient quantity of juice of Datura metel leaves for 24 hours and a final product was obtained in the form of Vati (tablet form. It is one of the formulations mentioned in Amavata (Rheumatoid Arthritis disease. The final products were subjected to Powder X-Ray Diffraction (XRD studies and values of XRD peaks of particular Panchavaktra ras were observed. This study revealed that high peaks of HgS (Metacinnabar, free S (Sulfur, Chabazite (Ca- exchanged, dehydrated Ca (structure- Rhombohedral in the final products. The structural and chemical characterization of the HgS (Metacinnabar found as cubic, free S (Sulphur as Orthorhombic in all the samples. The 50% strongest peaks of HgS were present at 2-Theta scale between 26-31, 43-44, 51-55, 70-72 degrees. This paper points out the importance of XRD, as a standard tool for further studies and research of Herbo-mineral formulations.

  4. A CMOS active pixel sensor system for laboratory- based x-ray diffraction studies of biological tissue.

    Science.gov (United States)

    Bohndiek, Sarah E; Cook, Emily J; Arvanitis, Costas D; Olivo, Alessandro; Royle, Gary J; Clark, Andy T; Prydderch, Mark L; Turchetta, Renato; Speller, Robert D

    2008-02-01

    X-ray diffraction studies give material-specific information about biological tissue. Ideally, a large area, low noise, wide dynamic range digital x-ray detector is required for laboratory-based x-ray diffraction studies. The goal of this work is to introduce a novel imaging technology, the CMOS active pixel sensor (APS) that has the potential to fulfil all these requirements, and demonstrate its feasibility for coherent scatter imaging. A prototype CMOS APS has been included in an x-ray diffraction demonstration system. An industrial x-ray source with appropriate beam filtration is used to perform angle dispersive x-ray diffraction (ADXRD). Optimization of the experimental set-up is detailed including collimator options and detector operating parameters. Scatter signatures are measured for 11 different materials, covering three medical applications: breast cancer diagnosis, kidney stone identification and bone mineral density calculations. Scatter signatures are also recorded for three mixed samples of known composition. Results are verified using two independent models for predicting the APS scatter signature: (1) a linear systems model of the APS and (2) a linear superposition integral combining known monochromatic scatter signatures with the input polychromatic spectrum used in this case. Cross validation of experimental, modelled and literature results proves that APS are able to record biologically relevant scatter signatures. Coherent scatter signatures are sensitive to multiple materials present in a sample and provide a means to quantify composition. In the future, production of a bespoke APS imager for x-ray diffraction studies could enable simultaneous collection of the transmitted beam and scattered radiation in a laboratory-based coherent scatter system, making clinical transfer of the technique attainable. PMID:18199908

  5. Helical rearrangement of photoactivated rhodopsin in monomeric and dimeric forms probed by high-angle X-ray scattering

    OpenAIRE

    Imamoto, Yasushi; Kojima, Keiichi; Oka, Toshihiko; Maeda, Ryo; Shichida, Yoshinori

    2015-01-01

    Light-induced helical rearrangement of vertebrate visual rhodopsin was directly monitored by high-angle X-ray scattering (HAXS), ranging from Q (= 4π sin θ/λ) = 0.03 Å-1 to Q = 1.5 Å-1. HAXS of nanodiscs containing a single rhodopsin molecule was performed before and after photoactivation of rhodopsin. The intensity difference curve obtained by HAXS agreed with that calculated from the crystal structure of dark state rhodopsin and metarhodopsin II, indicating that the conformational change of...

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Extensional rheometer for in situ x-ray scattering study on flow-induced crystallization of polymer

    Science.gov (United States)

    Liu, Yanping; Zhou, Weiqing; Cui, Kunpeng; Tian, Nan; Wang, Xiao; Liu, Liangbao; Li, Liangbin; Zhou, Yingui

    2011-04-01

    We designed and constructed an extensional rheometer for in situ small and wide angle x-ray study on flow-induced crystallization of polymer. Two rotating drums with an axis distance of 20 mm are employed to impose extensional deformation on the samples. With a constant angular velocity, the two drums generate a constant Henkcy strain rate as sample length for testing keeps constant during deformation. An ionic liquid is used as heating medium to prevent polymer melt from bending downward due to gravity, which is excellent in terms of high thermal stability, low viscosity, and relative low adsorption on x-ray. Flow-induced crystallization experiments are conducted with this apparatus on x-ray scattering station in Shanghai Synchrotron Radiation Facility (SSRF), which allows us to collect rheological and structural data simultaneously and may lead to a better understanding on flow-induced crystallization of polymer.

  11. X-ray excited optical luminescence, photoluminescence, photostimulated luminescence and x-ray photoemission spectroscopy studies on BaFBr:Eu

    CERN Document Server

    Subramanian, N; Govinda-Rajan, K; Mohammad-Yousuf; Santanu-Bera; Narasimhan, S V

    1997-01-01

    The results of x-ray excited optical luminescence (XEOL), photoluminescence (PL), photostimulated luminescence (PSL) and x-ray photoemission spectroscopy (XPS) studies on the x-ray storage phosphor BaFBr:Eu are presented in this paper. Analyses of XEOL, PL and PSL spectra reveal features corresponding to the transitions from 4f sup 6 td sup 1 to 4f sup 7 configurations in different site symmetries of Eu sup 2 sup +. Increasing x-ray dose is seen to lead to a red shift in the maximum of the PL excitation spectrum for the 391 nm emission. The XEOL and XPS spectra do not show any signature of Eu sup 3 sup + in the samples studied by us, directly raising doubts about the model of Takahashi et al in which Eu sup 2 sup + is expected to ionize to Eu sup 3 sup + upon x-ray irradiation and remain stable until photostimulation. XEOL and PSL experiments with simultaneous x-ray irradiation and He - Ne laser excitation as well as those with sequential x-ray irradiation and laser stimulation bring out the competition betwe...

  12. 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...

  13. Non-destructive determination of moisture content and micro-fibril angle of wood using a poly-chromatic X-ray beam theoretical and experimental approach

    International Nuclear Information System (INIS)

    Non-destructive determination of moisture content and micro-fibril angle are important stakes for the sciences of the wood because these two parameters influence strongly the macroscopic behavior of the wood. For example, the shrinkage, the mechanical properties, the thermal and acoustic conductivity are dependent on the moisture content and their anisotropic character is largely governed by the micro-fibril angle. We used the light difference between X-ray mass attenuation coefficient for the water and for the wood in transmission. Regrettably, the results show that this difference between X-ray mass attenuation coefficient is insufficient to allow the precise measurement of the moisture content.In spite of this, the coherent scattering shows sensitive effects. So, by using a poly-energetic beam and a spectrometric system, we were able to discriminate between the crystalline constituent (cellulose) of the amorphous constituent (water) in a sample of wet wood, because for a given angle these phases scatter in different energy. Besides, the device created allowed us to study the crystalline phase of the wood. We were able to confront experimental profiles of diffraction with theoretical profiles of diffraction, obtained by means of a rigorous simulation, in the objective to estimate the average micro-fibril angle and its standard deviation. (author)

  14. Preparation and X-ray Structural Study of Dibenziodolium Derivatives.

    Science.gov (United States)

    Postnikov, Pavel S; Guselnikova, Olga A; Yusubov, Mekhman S; Yoshimura, Akira; Nemykin, Victor N; Zhdankin, Viktor V

    2015-06-01

    New experimental procedures for the preparation of dibenziodolium salts by oxidative cyclization of 2-iodobiphenyl in the presence of appropriate strong acids are described. Particularly useful is a convenient one-pot synthesis of dibenziodolium hydrogen sulfate from 2-iodobiphenyl using Oxone as an inexpensive and environmentally safe oxidant. Dibenziodolium hydrogen sulfate, bis(triflyl)imidate, or triflate can be readily converted to various other dibenziodolium derivatives (chloride, bromide, thiocyanate, azide, cyanide, phenylsulfinate) by anion exchange. Structures of key products have been established by single-crystal X-ray diffraction analysis. Particularly interesting is the X-ray structure of dibenziodolium thiocyanate, which represents the first example of a structurally characterized hypervalent iodine compound with a relatively short iodine-sulfur secondary bond distance. PMID:25951091

  15. Preflight performance studies of the PoGOLite hard X-ray polarimeter

    CERN Document Server

    Chauvin, M; Kawano, T; Kiss, M; Kole, M; Mikhalev, V; Moretti, E; Takahashi, H; Pearce, M

    2015-01-01

    Polarimetric studies of astrophysical sources can make important contributions to resolve the geometry of the emitting region and determine the photon emission mechanism. PoGOLite is a balloon-borne polarimeter operating in the hard X-ray band (25-240 keV), with a Pathfinder mission focussing on Crab observations. Within the polarimeter, the distribution of Compton scattering angles is used to determine the polarisation fraction and angle of incident photons. To assure an unbiased measurement of the polarisation during a balloon flight it is crucial to characterise the performance of the instrument before the launch. This paper presents the results of the PoGOLite calibration tests and simulations performed before the 2013 balloon flight. The tests performed confirm that the polarimeter does not have any intrinsic asymmetries and therefore does not induce bias into the measurements. Generally, good agreement is found between results from test data and simulations which allows the polarimeter performance to be...

  16. PLEIADES: a picosecond Compton scattering x-ray source for advanced backlighting and time-resolved material studies

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, D J; Anderson, S G; Barty, C P; Betts, S M; Booth, R; Brown, W J; Crane, J K; Cross, R R; Fittinghoff, D N; Hartemann, F V; Kuba, J; Le Sage, G P; Tremaine, A M; Springer, P T; Rosenzweig, J B

    2003-10-20

    The PLEIADES (Picosecond Laser-Electron Inter-Action for the Dynamical Evaluation of Structures) facility has produced first light at 70 keV. This milestone offers a new opportunity to develop laser-driven, compact, tunable x-ray sources for critical applications such as diagnostics for the National Ignition Facility and time-resolved material studies. The electron beam was focused to 50 {micro}m rms, at 57 MeV, with 260 C of charge, a relative energy spread of 0.2%, and a normalized emittance of 5 mm mrad horizontally and 13 mm mrad vertically. The scattered 820-nm laser pulse had an energy of 180 mJ and a duration of 54 fs. Initial x-rays were captured with a cooled charge-coupled device using a Cesium Iodide scintillator; the peak photon energy was approximately 78 keV, with a total x-ray flux of 1.3 x 10{sup 6} photons/shot, and the observed angular distribution found to agree very well with three-dimensional codes. Simple K-edge radiography of a tantalum foil showed good agreement with the theoretical divergence-angle dependence of the x-ray energy. Optimization of the x-ray dose is currently underway, with the goal of reaching 10{sup 8} photons per shot and a peak brightness approaching 10{sup 20} photons/mm{sup 2}/mrad{sup 2}/s/0.1%bandwidth.

  17. Physiological and x-ray studies of potential antisickling agents.

    OpenAIRE

    Abraham, D. J.; Perutz, M F; Phillips, S E

    1983-01-01

    Several aromatic compounds have been found to inhibit the gelling of sickle cell hemoglobin. We have tried to correlate the antigelling activity of such compounds with the stereo-chemistry of their binding sites in the hemoglobin molecule. This approach led to the discovery that two known antilipoproteinemia drugs, clofibrate and gemfibrozil, have antigelling activity. X-ray analysis showed that three pairs of molecules of clofibric acid, the active metabolite of clofibrate, bound to the wall...

  18. High energy x-ray reflectivity and scattering study from spectrum-x-gamma flight mirrors

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Budtz-Jørgensen, Carl; Frederiksen, P. Kk;

    1993-01-01

    Line radiation from Fe K-alpha(1), Cu K-alpha(1), and Ag K-alpha(1) is used to study the high energy X-ray reflectivity and scattering behavior of flight-quality X-ray mirrors having various Al substrates. When both the specular and the scattered radiation are integrated, near theoretical...

  19. Iron overload of human colon adenocarcinoma cells studied by synchrotron-based X-ray techniques

    NARCIS (Netherlands)

    Mihucz, Victor G.; Meirer, Florian; Polgári, Zsófia; Réti, Andrea; Pepponi, Giancarlo; Ingerle, Dieter; Szoboszlai, Norbert; Streli, Christina

    2016-01-01

    Fast- and slow-proliferating human adenocarcinoma colorectal cells, HT-29 and HCA-7, respectively, overloaded with transferrin (Tf), Fe(III) citrate, Fe(III) chloride and Fe(II) sulfate were studied by synchrotron radiation total-reflection X-ray spectrometry (TXRF), TXRF-X-ray absorption near edge

  20. Synthesis of Novel Amphiphilic Azobenzenes and X-ray Scattering Studies of Their Langmuir Monolayers

    DEFF Research Database (Denmark)

    Sørensen, Thomas Just; Kjær, Kristian; Breiby, Dag Werner;

    2008-01-01

    air-water interface, the amphiphilic azobenzenes form noncrystalline but stable Langmuir films that display an unusual reversible monolayer collapse close to 35 mN/m. The structures and phase transitions were studied by X-ray reflectivity (XR) and grazing-incidence X-ray diffraction, both utilizing...

  1. Enrichment study of hot intra-cluster gas through X-ray spectroscopy

    NARCIS (Netherlands)

    Plaa, J. de

    2007-01-01

    Enrichment study of hot intra-cluster gas through X-ray spectroscopy Clouds of hot X-ray emitting gas associated with clusters of galaxies are the biggest aggregates of baryons that we know, except for the cosmic web. A typical cloud contains the nuclear-fusion products of billions of supernovae. Th

  2. X-Ray and Neutron Scattering Study of the Magnetic Structure of Neodymium Metal

    DEFF Research Database (Denmark)

    Lebech, Bente; Als-Nielsen, Jens Aage; McEwen, K. A.

    1979-01-01

    A combined x-ray and neutron diffraction study has shown that the so-called "triple-q⃗" structure is not the correct model of the magnetic structure of neodymium. The x-ray data showed only the Bragg reflections originating from the double-hcp lattice. Hence, all additional reflections observed b...

  3. High-resolution x-ray studies of an AXAF high-energy transmission grating

    DEFF Research Database (Denmark)

    Abdali, S.; Christensen, Finn Erland; Schnopper, H. W.;

    1993-01-01

    A triple axis X-ray diffractometer, designed and built at the Danish Space Research Institute, was used to make a high resolution study of the performance of a 2000 angstroms period, high energy X-ray transmission grating developed at MIT for one of the grating spectrometers on the Advanced X...

  4. Accurate structure analyses of polymer crystals on the basis of wide-angle X-ray and neutron diffractions

    International Nuclear Information System (INIS)

    The crystal structure analysis of various polymer substances has been reviewed on the basis of wide-angle high-energy X-ray and neutron diffraction data. The progress in structural analytical techniques of polymer crystals have been reviewed at first. The structural models proposed so far were reinvestigated and new models have been proposed for various kinds of polymer crystals including polyethylene, poly(vinyl alcohol), poly(lactic acid) and its stereocomplex etc. The hydrogen atomic positions were also clarified by the quantitative analysis of wide-angle neutron diffraction data, from which the physical properties of polymer crystals have been evaluated theoretically. The bonded electron density distribution has been estimated for a polydiacetylene single crystal on the basis of the so-called X-N method or by the combination of structural information derived from X-ray and neutron diffraction data analysis. Some comments have been added about future developments in the field of structure-property relationship determination. (author)

  5. A statistical study of the relation between soft X-ray excess and accretion disk

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    To study the origin of the soft X-ray excess,we compile a sample of 94 unobscured,radio-quiet QSOs and Seyfert galaxies with available data from GALEX and ROSAT.We find that 50 sources show strong soft X-ray excess and the other 44 show weak/no soft X-ray excess.Systematic analyses of the data indicate that the difference in soft X-rays is mainly but not only resulting from different accretion rates(in units of Eddington rate).The statistical study of the sources with soft X-ray excess shows that the strength of soft X-ray excess weakly and positively correlates with the Eddington ratio and increases with the increase of the strength of UV radiations relative to the X-rays.Provided that the UV emissions are from the thin disk,the correlations imply that the origin of soft X-ray excess is associated with the thin disk,either by means of Comptonization of the disk photons or in some other ways.

  6. Time-resolved X-ray studies using third generation synchrotron radiation sources

    International Nuclear Information System (INIS)

    The third generation, high-brilliance, hard x-ray, synchrotron radiation (SR) sources currently under construction (ESRF at Grenoble, France; APS at Argonne, Illinois; and SPring-8 at Harima, Japan) will usher in a new era of x-ray experimentation for both physical and biological sciences. One of the most exciting areas of experimentation will be the extension of x-ray scattering and diffraction techniques to the study of transient or time-evolving systems. The high repetition rate, short-pulse duration, high brilliance, and variable spectral bandwidth of these sources make them ideal for x-ray time-resolved studies. The temporal properties (bunch length, interpulse period, etc.) of these new sources will be summarized. Finally, the scientific potential and the technological challenges of time-resolved x-ray scattering from these new sources will be described. 13 refs., 4 figs

  7. Novel detector design for reducing intercell x-ray cross-talk in the variable resolution x-ray CT scanner: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Arabi, Hosein; Asl, Ali Reza Kamali; Ay, Mohammad Reza; Zaidi, Habib [Department of Radiation Medicine, Shahid Beheshti University, 1983963113 Tehran (Iran, Islamic Republic of); Research Centre for Science and Technology in Medicine, Tehran University of Medical Sciences, 1417613151 Tehran (Iran, Islamic Republic of); Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, 1417613151 Tehran (Iran, Islamic Republic of); and Research Institute for Nuclear Medicine, Tehran University of Medical Sciences, 1417613151 Tehran (Iran, Islamic Republic of); Division of Nuclear Medicine, Geneva University Hospital, CH-1211 Geneva (Switzerland); Geneva Neuroscience Center, Geneva University, CH-1211 Geneva (Switzerland) and Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, 9700 RB Groningen (Netherlands)

    2011-03-15

    Purpose: The variable resolution x-ray (VRX) CT scanner provides substantial improvement in the spatial resolution by matching the scanner's field of view (FOV) to the size of the object being imaged. Intercell x-ray cross-talk is one of the most important factors limiting the spatial resolution of the VRX detector. In this work, a new cell arrangement in the VRX detector is suggested to decrease the intercell x-ray cross-talk. The idea is to orient the detector cells toward the opening end of the detector. Methods: Monte Carlo simulations were used for performance assessment of the oriented cell detector design. Previously published design parameters and simulation results of x-ray cross-talk for the VRX detector were used for model validation using the GATE Monte Carlo package. In the first step, the intercell x-ray cross-talk of the actual VRX detector model was calculated as a function of the FOV. The obtained results indicated an optimum cell orientation angle of 28 deg. to minimize the x-ray cross-talk in the VRX detector. Thereafter, the intercell x-ray cross-talk in the oriented cell detector was modeled and quantified. Results: The intercell x-ray cross-talk in the actual detector model was considerably high, reaching up to 12% at FOVs from 24 to 38 cm. The x-ray cross-talk in the oriented cell detector was less than 5% for all possible FOVs, except 40 cm (maximum FOV). The oriented cell detector could provide considerable decrease in the intercell x-ray cross-talk for the VRX detector, thus leading to significant improvement in the spatial resolution and reduction in the spatial resolution nonuniformity across the detector length. Conclusions: The proposed oriented cell detector is the first dedicated detector design for the VRX CT scanners. Application of this concept to multislice and flat-panel VRX detectors would also result in higher spatial resolution.

  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. Protein folding and protein metallocluster studies using synchrotron small angler X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Eliezer, D.

    1994-06-01

    Proteins, biological macromolecules composed of amino-acid building blocks, possess unique three dimensional shapes or conformations which are intimately related to their biological function. All of the information necessary to determine this conformation is stored in a protein`s amino acid sequence. The problem of understanding the process by which nature maps protein amino-acid sequences to three-dimensional conformations is known as the protein folding problem, and is one of the central unsolved problems in biophysics today. The possible applications of a solution are broad, ranging from the elucidation of thousands of protein structures to the rational modification and design of protein-based drugs. The scattering of X-rays by matter has long been useful as a tool for the characterization of physical properties of materials, including biological samples. The high photon flux available at synchrotron X-ray sources allows for the measurement of scattering cross-sections of dilute and/or disordered samples. Such measurements do not yield the detailed geometrical information available from crystalline samples, but do allow for lower resolution studies of dynamical processes not observable in the crystalline state. The main focus of the work described here has been the study of the protein folding process using time-resolved small-angle x-ray scattering measurements. The original intention was to observe the decrease in overall size which must accompany the folding of a protein from an extended conformation to its compact native state. Although this process proved too fast for the current time-resolution of the technique, upper bounds were set on the probable compaction times of several small proteins. In addition, an interesting and unexpected process was detected, in which the folding protein passes through an intermediate state which shows a tendency to associate. This state is proposed to be a kinetic molten globule folding intermediate.

  10. Protein folding and protein metallocluster studies using synchrotron small angler X-ray scattering

    International Nuclear Information System (INIS)

    Proteins, biological macromolecules composed of amino-acid building blocks, possess unique three dimensional shapes or conformations which are intimately related to their biological function. All of the information necessary to determine this conformation is stored in a protein's amino acid sequence. The problem of understanding the process by which nature maps protein amino-acid sequences to three-dimensional conformations is known as the protein folding problem, and is one of the central unsolved problems in biophysics today. The possible applications of a solution are broad, ranging from the elucidation of thousands of protein structures to the rational modification and design of protein-based drugs. The scattering of X-rays by matter has long been useful as a tool for the characterization of physical properties of materials, including biological samples. The high photon flux available at synchrotron X-ray sources allows for the measurement of scattering cross-sections of dilute and/or disordered samples. Such measurements do not yield the detailed geometrical information available from crystalline samples, but do allow for lower resolution studies of dynamical processes not observable in the crystalline state. The main focus of the work described here has been the study of the protein folding process using time-resolved small-angle x-ray scattering measurements. The original intention was to observe the decrease in overall size which must accompany the folding of a protein from an extended conformation to its compact native state. Although this process proved too fast for the current time-resolution of the technique, upper bounds were set on the probable compaction times of several small proteins. In addition, an interesting and unexpected process was detected, in which the folding protein passes through an intermediate state which shows a tendency to associate. This state is proposed to be a kinetic molten globule folding intermediate

  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. Amplitude and phase changes on VLF/LF radio signals depending on solar zenith angle during occurrences of solar X-ray flares

    Science.gov (United States)

    Sulic, Desanka; Sreckovic, Vladimir; Mihajlov, A. A.

    2016-07-01

    The focus of this work is on the extraction of D-region electron density that is induced by the intensive X-ray flux under different solar zenith angle. The sensitivity of Very Low and Low Frequency (VLF and LF) propagation in the lower ionosphere makes it an ideal probe for remotely sensing the ambient state and localized perturbations of the ionosphere. The basis of this work is amplitude and phase data acquired by monitoring DHO/23.40 kHz and NSC/45.90 kHz radio signals during the period of ascending and maximum of the solar cycle 24. All the data were recorded at Belgrade station (44.85 ^{0} N, 20.38 ^{0} E) by AWESOME system. DHO-BEL and NSC-BEL are short paths with distances of 1300 and 953 km, respectively. These paths are in the same time zone. The diurnal amplitude and phase variations on VLF/LF radio signal against time vary in characteristic ways that are caused by solar zenith angles over path. Two amplitude minima are observed when sunrise and sunset terminators reach the middle of the propagation path. During daytime condition there are two amplitude minima (in morning and afternoon) developed under solar zenith angles χ ˜80 ^{0} over short path. In this study we considered amplitude and phase perturbations on VLF/LF radio signal induced by solar X-ray flares under solar zenith angles which are close with timings of amplitude minima during daytime under normal ionospheric condition. We expected and estimated differences in amplitude and phase perturbations on DHO/23.40 kHz and NSC/45.90 kHz radio signals induced by solar X-ray flares which occurrences are under solar zenith angles χ ≤ 80 ^{0}. The observations include solar flares with magnitudes in the range from C2 (I_{X} = 2 10^{-6} Wm^{-2} of X-ray flux in the band at 0.1 - 0.8 nm) to X2.1 (I_{X} = 2.1 10^{-4} Wm^{-2}) class. For example on 11 March 2015 occurred X2.1 class flare with maximum of intensity at 16:22 UT, when solar angle was χ = 81^{0} at Belgrade. One day before, under normal

  14. Calculations and surface quality measurements of high-asymmetry angle x-ray crystal monochromators for advanced x-ray imaging and metrological applications

    Science.gov (United States)

    Zápražný, Zdenko; Korytár, Dušan; Jergel, Matej; Šiffalovič, Peter; Dobročka, Edmund; Vagovič, Patrik; Ferrari, Claudio; Mikulík, Petr; Demydenko, Maksym; Mikloška, Marek

    2015-03-01

    We present the numerical optimization and the technological development progress of x-ray optics based on asymmetric germanium crystals. We show the results of several basic calculations of diffraction properties of germanium x-ray crystal monochromators and of an analyzer-based imaging method for various asymmetry factors using an x-ray energy range from 8 to 20 keV. The important parameter of highly asymmetric monochromators as image magnifiers or compressors is the crystal surface quality. We have applied several crystal surface finishing methods, including advanced nanomachining using single-point diamond turning (SPDT), conventional mechanical lapping, chemical polishing, and chemomechanical polishing, and we have evaluated these methods by means of atomic force microscopy, diffractometry, reciprocal space mapping, and others. Our goal is to exclude the chemical etching methods as the final processing technique because it causes surface undulations. The aim is to implement very precise deterministic methods with a control of surface roughness down to 0.1 nm. The smallest roughness (˜0.3 nm), best planarity, and absence of the subsurface damage were observed for the sample which was machined using an SPDT with a feed rate of 1 mm/min and was consequently polished using a fine polishing 15-min process with a solution containing SiO2 nanoparticles (20 nm).

  15. X-ray studies of polymer/gold nanocomposites

    International Nuclear Information System (INIS)

    We demonstrate that x-ray reflection standing wave fluorescence spectroscopy is a highly sensitive technique for the determination of the distribution of metal nanoparticles inside polymer thin films. We investigate both the depth profile and the in-plane spatial correlation of gold nanoparticles in an asymmetric polystyrene-b-poly(2-vinylpyridine) block copolymer film. These copolymer films self-assemble into alternating, nanometer-sized domains that are, upon annealing, selectively decorated by thermally evaporated metal nanoparticles to form metal/polymer composites. copyright 1999 American Institute of Physics

  16. Some studies on low-frequency signal in relation to X-ray flares and climatic conditions

    Directory of Open Access Journals (Sweden)

    S. K. Sarkar

    Full Text Available The statistical behaviour of the sudden enhancement in signal strength (SES in relation to solar X-ray flares has been studied for the near east-west propagation of 40 kHz radio waves from Sanwa (36°11'N; 139°51'E in Japan to Calcutta (22°34'N; 88°24'E over a long distance path of 5100 km for a period of two years. The period has been divided into four phases - P1, P2, P3 and P4, according to the position of the overhead sun. The change in signal strength during X-ray flares is dependent on the solar zenith angle and climatic conditions. The statistical modal values of the time lag of the SES peak with respect to that solar X-ray flare is found to increase as solar zenith angle increases. The relative rates of increase and decrease of the signal strength (RRISS and RRDSS respectively have been evaluated for a number of SES which are related to large X-ray flares. Their characteristics have also been investigated. The modal values of the relaxation time have been found to be highly correlated with climatic conditions like temperature and humidity of the propagation path.

  17. The soft x-ray instrument for materials studies at the linac coherent light source x-ray free-electron laser

    OpenAIRE

    Schlotter, W. F.; Turner, J. J.; Fernández-Perea, M.; Kelez, N.; Lee, S.; Coffee, R.; Hays, G.; Beye, M; Gerken, N.; Sorgenfrei, F.; Hau-Riege, S.; Juha, L.; Rowen, M; Chalupsky, J.; Hajkova, V

    2012-01-01

    The soft x-ray materials science instrument is the second operational beamline at the linac coherent light source x-ray free electron laser. The instrument operates with a photon energy range of 480-2000 eV and features a grating monochromator as well as bendable refocusing mirrors. A broad range of experimental stations may be installed to study diverse scientific topics such as: ultrafast chemistry, surface science, highly correlated electron systems, matter under extreme conditions, and la...

  18. Magnetic dichroism in angle-resolved hard x-ray photoemission from buried layers

    Science.gov (United States)

    Kozina, Xeniya; Fecher, Gerhard H.; Stryganyuk, Gregory; Ouardi, Siham; Balke, Benjamin; Felser, Claudia; Schönhense, Gerd; Ikenaga, Eiji; Sugiyama, Takeharu; Kawamura, Naomi; Suzuki, Motohiro; Taira, Tomoyuki; Uemura, Tetsuya; Yamamoto, Masafumi; Sukegawa, Hiroaki; Wang, Wenhong; Inomata, Koichiro; Kobayashi, Keisuke

    2011-08-01

    This work reports the measurement of magnetic dichroism in angular-resolved photoemission from in-plane magnetized buried thin films. The high bulk sensitivity of hard x-ray photoelectron spectroscopy (HAXPES) in combination with circularly polarized radiation enables the investigation of the magnetic properties of buried layers. HAXPES experiments with an excitation energy of 8 keV were performed on exchange-biased magnetic layers covered by thin oxide films. Two types of structures were investigated with the IrMn exchange-biasing layer either above or below the ferromagnetic layer: one with a CoFe layer on top and another with a Co2FeAl layer buried beneath the IrMn layer. A pronounced magnetic dichroism is found in the Co and Fe 2p states of both materials. The localization of the magnetic moments at the Fe site conditioning the peculiar characteristics of the Co2FeAl Heusler compound, predicted to be a half-metallic ferromagnet, is revealed from the magnetic dichroism detected in the Fe 2p states.

  19. 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

  20. Synchrotron X-ray Scattering Studies of Poly(lactide) Electrospun Fibers Containing Carbon Nanotubes

    Science.gov (United States)

    Zhu, Yazhe; Cebe, Peggy

    2014-03-01

    Carbon nanotubes(CNTs) often serve as an effective nucleating agent that facilitates the crystallization of semicrystalline polymers. Here we study the influence of CNTs on thermal and structural properties of Poly-lactide (PLA), which is well-known as a biodegradable and biocompatible thermoplastic polymer. The effect of CNTs on the crystallization and melting behavior of electrospun fibers of poly (L-lactide) (PLLA, with 100% L-isomer) and poly (D-lactide) (PDLA, containing 4% D-isomer) was systemically studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform spectroscopy(FT-IR) and real time synchrotron wide-angle X-ray scattering (WAXS) . Multi-walled CNTs were co-electrospun with the poly(lactides) in weight ratios ranging from 0.1 to 4.0 wt% MW-CNT. PLA/carbon nanotubes composite electrospun fibers were successfully produced by appropriate choice of processing conditions and solution concentration. The morphologies of neat and CNT-filled electrospun nanofibers were observed by scanning electron microscopy. WAXS and DSC results show that lower content of CNTs contributes to higher speed of crystallization. However the results also showed that at the highest concentration of CNTs the ultimate crystallinity was reduced. FTIR and X-ray results show that PLA fibers have different crystal forms at high and low crystallization temperature. DSC results also show that D-lactide has reduced crystallinity compared to L-lactide.

  1. High-pressure powder x-ray diffraction study of EuVO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Garg, Alka B. [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Errandonea, D., E-mail: daniel.errandonea@uv.es [Departamento de Física Aplicada—ICMUV, MALTA Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia (Spain)

    2015-03-15

    The high-pressure structural behavior of europium orthovanadate has been studied using in-situ, synchrotron based, high-pressure x-ray powder diffraction technique. Angle-dispersive x-ray diffraction measurements were carried out at room temperature up to 34.7 GPa using a diamond-anvil cell, extending the pressure range reported in previous experiments. We confirmed the occurrence of zircon–scheelite phase transition at 6.8 GPa and the coexistence of low- and high-pressure phases up to 10.1 GPa. In addition, clear evidence of a scheelite–fregusonite transition is found at 23.4 GPa. The fergusonite structure remains stable up to 34.7 GPa, the highest pressure reached in the present measurements. A partial decomposition of EuVO{sub 4} was also observed from 8.1 to 12.8 GPa; however, this fact did not preclude the identification of the different crystal structures of EuVO{sub 4}. The crystal structures of the different phases have been Rietveld refined and their equations of state (EOS) have been determined. The results are compared with the previous experimental data and theoretical calculations. - Graphical abstract: The high-pressure structural sequence of EuVO{sub 4}. - Highlights: • EuVO{sub 4} is studied under pressure up to 35 GPa using synchrotron XRD. • The zircón–scheelite–fergusonite structural sequence is observed. • Crystal structures are refined and equations of state determined.

  2. Timing and Spectroscopy of Accreting X-ray Pulsars: the State of Cyclotron Line Studies

    CERN Document Server

    Heindl, W A; Coburn, W; Staubert, R; Wilms, J; Kreykenbohm, I; Kretschmar, P

    2004-01-01

    A great deal of emphasis on timing in the RXTE era has been on pushing toward higher and higher frequency phenomena, particularly kHz QPOs. However, the large areas of the RXTE pointed instruments provide another capability which is key for the understanding of accreting X-ray pulsars -- the ability to accumulate high quality spectra in a limited observing time. For the accreting X-ray pulsars, with their relatively modest spin frequencies, this translates into an ability to study broad band spectra as a function of pulse phase. This is a critical tool, as pulsar spectra are strong functions of the geometry of the "accretion mound" and the observers' viewing angle to the ~10^12 G magnetic field. In particular, the appearance of "cyclotron lines" is sensitively dependent on the viewing geometry, which must change with the rotation of the star. These spectral features, seen in only a handful of objects, are quite important, as they give us our only direct measure of neutron star magnetic fields. Furthermore, th...

  3. Grazing incidence X-ray reflectivity - Studies for the AXAF observatory

    Science.gov (United States)

    Slane, P.; Schwartz, D.; Van Speybroeck, L.; Jones, D.; Chappell, J.; Bilbro, J.; Shapiro, A.; Dave, S.; Kidd, P.; Texter, S.

    1992-01-01

    The energy bandwidth and total throughput of a grazing incidence optics system is a strong function of the X-ray reflectivity of the surface coating. In support of the Advanced X-ray Astrophysics Facility (AXAF), studies are underway to evaluate and characterize the reflectivity of potential AXAF coatings. Here we report on results obtained for Au, Ir, and Ni coatings produced by electron-beam evaporation, evaporation with ion-assist, and sputtering. Effects of coating thickness and deposition angle have been evaluated at 6.4 and 8.1 keV; the highest reflectivities are those of the thinner, about 200 A vs about 700 A, coatings. While considerable variations exist, the best Ir samples have higher reflectivity than any of the Au coatings. Data results have been compared with models for theoretical reflectivity, particularly with regard to the effective density of the coatings. Independent measurements of the coating densities have been carried out for comparison with the reflectivity results.

  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. X-ray Studies of Planetary Systems: An Astro2010 Decadal Survey White Paper

    CERN Document Server

    Feigelson, Eric; Elsner, Ronald; Glassgold, Alfred; Gudel, Manuel; Montmerle, Thierry; Ohashi, Takaya; Smith, Randall; Wargelin, Bradford; Wolk, Scott

    2009-01-01

    While it may seem counterintuitive that X-ray astronomy should give any insights into low-temperature planetary systems, planets orbit stars whose magnetized surfaces divert a small fraction of the stellar energy into high energy products: coronal UV and X-rays, flare X-rays and energetic particles, and a high-velocity stellar wind. In our Solar System, X-ray emission gives unique insights into the solar activity, planetary atmospheres, cometary comae, charge exchange physics, and space weather across the Solar System. The stellar activity of young stars is greatly elevated and can substantially affect protoplanetary disks and planet formation processes. We highlight six studies achievable with the planned International X-ray Observatory which address in unique ways issues in planetary sciences: probing X-ray irradiation of protoplanetary disks with the iron fluorescent line and its effects on disk turbulence; study the complex charge-exchange X-ray emission from Jupiter and the Martian exosphere; elucidate c...

  6. LIGHT SOURCE: A simulation study of Tsinghua Thomson scattering X-ray source

    Science.gov (United States)

    Tang, Chuan-Xiang; Li, Ren-Kai; Huang, Wen-Hui; Chen, Huai-Bi; Du, Ying-Chao; Du, Qiang; Du, Tai-Bin; He, Xiao-Zhong; Hua, Jian-Fei; Lin, Yu-Zhen; Qian, Hou-Jun; Shi, Jia-Ru; Xiang, Dao; Yan, Li-Xin; Yu, Pei-Cheng

    2009-06-01

    Thomson scattering X-ray sources are compact and affordable facilities that produce short duration, high brightness X-ray pulses enabling new experimental capacities in ultra-fast science studies, and also medical and industrial applications. Such a facility has been built at the Accelerator Laboratory of Tsinghua University, and upgrade is in progress. In this paper, we present a proposed layout of the upgrade with design parameters by simulation, aiming at high X-ray pulses flux and brightness, and also enabling advanced dynamics studies and applications of the electron beam. Design and construction status of main subsystems are also presented.

  7. A simulation study of Tsinghua Thomson scattering X-ray source

    Institute of Scientific and Technical Information of China (English)

    TANG Chuan-Xiang; LI Ren-Kai; HUANG Wen-Hui; CHEN Huai-Bi; DU Ying-Chao; DU Qiang; DU Tai-Bin; HE Xiao-Zhong; HUA Jian-Fei; LIN Yu-Zhen; QIAN Hou-Jun; SHI Jia-Ru; XIANG Dao; YAN Li-Xin; Yu Pei-Cheng

    2009-01-01

    Thomson scattering X-ray sources are compact and afrordable facifities that produce short duration,high brightness X-ray pulses enabling new experimental capacities in ultra-fast science studies,and also medical and industrial applications.Such a facility has been built at the Accelerator Laboratory of Tsinghua University,and upgrade is in progress.In this paper,we present a proposed layout of the upgrade with design parameters by simulation,aiming at high X-ray pulses flux and brightness,and also enabling advanced dynamics studies and applications of the electron beam.Design and construction status of main subsystems are also presented.

  8. Resonant Soft X-ray Spectroscopic Studies of Light Actinides and Copper Systems

    OpenAIRE

    Modin, Anders

    2009-01-01

    Light actinides and copper systems were studied using resonant soft X-ray spectroscopy. An instrumental and experimental setup for soft X-ray spectroscopy meeting the requirements of a closed source for radioactivity was developed and described in detail. The setup was used for studies of single-crystal PuO2 oxidation. The existence of higher oxidation state than Pu(IV) in some surface areas of the single crystal were found from O 1s X-ray absorption measurements. Furthermore, from comparison...

  9. 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.)

  10. Pinpointing the base of the AGN jets through general relativistic X-ray reverberation studies

    CERN Document Server

    Emmanoulopoulos, D

    2014-01-01

    Many theoretical models of Active Galactic Nuclei (AGN) predict that the X-ray corona, lying above the black hole, constitutes the base of the X-ray jet. Thus, by studying the exact geometry of the close black hole environment, we can pinpoint the launching site of the jet. Detection of negative X-ray reverberation time delays (i.e. soft band X-ray variations lagging behind the corresponding hard band X-ray variations) can yield significant information about the geometrical properties of the AGN, such as the location of the X-ray source, as well as the physical properties of the the black hole, such as its mass and spin. In the frame-work of the lamp-post geometry, I present the first systematic X-ray time-lag modelling results of an ensemble of 12 AGN, using a fully general relativistic (GR) ray tracing approach for the estimation of the systems' response functions. By combing these state-of-the art GR response models with statistically innovative fitting routines, I derive the geometrical layout of the clos...

  11. Environmental studies in Khartoum area using x-ray fluorescence

    International Nuclear Information System (INIS)

    In the present work an attempt has been made for the analysis of some soil, plant, sediments and fish samples of relevance to environmental pollution in Khartoum area. These samples have been collected from different places in residential areas, so as to cover industrial areas, agricultural and residential areas, as well as Tuti Island as control area. Special attention has been dedicated to the analysis of lead concentrations resulting from automobile-emissions in soils and to other toxic metals such as Cr in some industries. The samples were analysed by x-ray fluorescence (XRF) technique. The results obtained using XRF measurements and computer software called QXAS for data analysis. The concentrations of lead and some heavy metals such as Cr in soils from certain locations were alarming and may create pollution problems in the near future. The results obtained from different countries. The results are generally lower than the international limits. (Author)

  12. Studies of soft x-ray emission during solar flares

    International Nuclear Information System (INIS)

    Solar flare soft x-ray emission from 0.5 A to 8.5 A was observed during 1967-68 by Bragg crystal (LiF and EDDT) spectrometers aboard the OSO-4 satellite and also by NRL broad-band ionization detectors aboard the OGO-4 satellite. In this work, instrumental parameters for the LiF crystal spectrometer based on experimental values have been determined and used in the data analysis. The total continuum emission in the 0.5 to 3 A and the 1 to 8 A broad band segments has been determined from OGO-4 data for 21 flares. In doing this, a simple and approximate method of converting the total emission based on the gray body approximation (in which the OGO-4 data are reported) to one based on the thermal continuum spectrum has been developed. (author)

  13. Soft X-ray emission studies of biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Kurmaev, E.Z. E-mail: kurmaev@ifmlrs.uran.ru; Werner, J.P.; Moewes, A.; Chiuzbaian, S.; Bach, M.; Ching, W.-Y.; Motozaki, W.; Otsuka, T.; Matsuya, S.; Endo, K.; Neumann, M

    2004-07-01

    Soft X-ray fluorescence measurements are used to characterize three groups of biomaterials: Vitamin B{sub 12} and derivatives, antioxidants (aspirin and paracetamol), and human teeth. We show that the chemical bonding in Vitamin B{sub 12} is characterized by the strong Co-C bond and the relatively weak Co-N bond. The Co-C bond in cyanocobalamin is found to be stronger than that of methylcobalamin leading to their different biological activity. The chemical bonding of paracetamol and aspirin is characterized by the formation of oxygen lone-pair {pi}-orbitals, which can neutralize free radicals and therefore be related to antioxidant activity of these compounds. Carbon K{alpha} emission spectra of a caries lesion suggest that the CaCO{sub 3} like phase exists in sound enamel and that a selective loss of carbonate occurs during the early stages of a caries attack.

  14. X-ray photoemission spectroscopy study of zirconium hydride

    International Nuclear Information System (INIS)

    X-ray photoemission spectroscopy (XPS) measurements are reported for ZrH/sub 1.65/ and Zr metal. The valence-band measurements are compared with available band-theory density-of-states calculations for the metal and hydride. The hydride spectrum differs significantly from the metal spectrum. Most important, a strong peak associated with hydrogen s electrons appears approximately 7 eV below the Fermi level. XPS measurements of Zr 4p core levels show a binding-energy shift of 1 eV between Zr metal and ZrH/sub 1.65/. It is argued that this shift results from charge readjustment in the vicinity of the Zr site. With the addition of hydrogen, net charge must be transferred from the Zr site to the hydrogen site. A charge-density analysis based on simplified cluster calculations is presented

  15. 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 ...

  16. 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.

  17. 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.

  18. 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.

  19. Turbulent pitch-angle scattering and diffusive transport of hard-X-ray producing electrons in flaring coronal loops

    CERN Document Server

    Kontar, E P; Emslie, A G; Vilmer, N

    2013-01-01

    Recent observations from {\\em RHESSI} have revealed that the number of non-thermal electrons in the coronal part of a flaring loop can exceed the number of electrons required to explain the hard X-ray-emitting footpoints of the same flaring loop. Such sources cannot, therefore, be interpreted on the basis of the standard collisional transport model, in which electrons stream along the loop while losing their energy through collisions with the ambient plasma; additional physical processes, to either trap or scatter the energetic electrons, are required. Motivated by this and other observations that suggest that high energy electrons are confined to the coronal region of the source, we consider turbulent pitch angle scattering of fast electrons off low frequency magnetic fluctuations as a confinement mechanism, modeled as a spatial diffusion parallel to the mean magnetic field. In general, turbulent scattering leads to a reduction of the collisional stopping distance of non-thermal electrons along the loop and ...

  20. 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

  1. 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.

  2. Study of dielectric liquids at room temperature for high energy x ray Tomography

    International Nuclear Information System (INIS)

    The detection of X rays by means of a dielectric liquid detector system, at room temperature, is discussed. The physico-chemical properties of a dielectric liquid, the construction of a cleaning device and of two electrode configurations, and the utilization of different amplifier models are studied. The results allowed the analysis and characterization of the behavior of the dielectric liquid under X ray irradiation. Data obtained is confirmed by computerized simulation. The choice of Tetramethyl-germanium for the X ray tomography, applied in nondestructive analysis, is explained. The investigation of the system parameters allowed the setting of the basis of a prototype project for a multi-detector

  3. X-ray diffraction studies of NbTe2 single crystal

    Indian Academy of Sciences (India)

    Neha Bhatt; Rajiv Vaidya; S G Patel; A R Jani

    2004-02-01

    NbTe2 is a member of transition metal dichalcogenide (TMDC) group. Single crystals of niobium ditelluride (NbTe2) have been grown by a chemical vapour transport technique using iodine as transporting agent. The composition of the grown crystals was confirmed on the basis of energy dispersive analysis by X-ray (EDAX) and remaining structural characterization was also accomplished by X-ray diffraction (XRD) studies. Lattice parameters, volume and X-ray density have been carried out for the grown crystals. The particle size for a number of reflections has been calculated using Scherrer’s formula.

  4. X-ray scattering and absorption studies of MnAs/GaAs heterostructures

    Science.gov (United States)

    Huang, S.; Ming, Z. H.; Soo, Y. L.; Kao, Y. H.; Tanaka, M.; Munekata, H.

    1996-02-01

    Ferromagnetic MnAs thin films grown on GaAs (001) substrates by molecular-beam epitaxy have been studied by the methods of grazing incidence x-ray scattering, x-ray diffraction, and extended x-ray-absorption fine structure. Microstructures in two films prepared with different first-layer growth conditions (template effects) are compared in terms of the interfacial roughness in the layer structure, lattice constants, epilayer thickness, local environment surrounding the Mn atoms, coordination number, and local disorder. Our results indicate that the template effects can cause significant differences in the local structures and crystallinity of the MnAs epitaxial layers.

  5. X-ray diffraction and mechanical properties studies on Kevlar-49 fibres

    International Nuclear Information System (INIS)

    The thesis deals with the effect of annealing in the temperature range 150-500 degrees celsius, and long-term ageing (1-150 days) at 150 degrees celsius, on the structure and mechanical properties of Kevlar-49 fibres. Wide-angle x-ray diffraction techniques were used to characterize quantitatively the structure in terms of crystallinity, crystallite size and orientation. The mechanical properties were characterized in terms of initial Young's modulus, tensile strength, and elongation at break. Thermogravimetric analysis was performed to determine the loss in weight after annealing. Differential Thermal Analysis (DTA) scan was performed to determine the 'peak melting point' of the untreated Kevlar-49 fibres. The surface topography, fracture behaviour and microfibrillar character of Kevlar-49 were studied in a scanning electron microscope. 52 refs., 30 figs., 6 tabs. (A.M.H.)

  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. Synchrotron X-Ray Study on Structures of Ni80Fe20/Cu Superlattices

    Institute of Scientific and Technical Information of China (English)

    XU Ming; LUO Guang-Ming; CHAI Chun-Lin; YANG Tao; MAI Zhen-Hong; LAI Wu-Yan; WU Zhong-Hua; WANG De-Wu

    2001-01-01

    We have shown that, in contrast to the results in the literature, the Bragg peak intensity of Ni80Fe20/Cu superlattices is enhanced at the incident x-ray energy slightly higher than the absorption edge of the heavier element (Cu). The atomic density at Ni80Fe20/Cu interface was analysed by the diffraction anomalous fine structure technology with the incident angle of x-ray fixed at the first Bragg peak. Our results demonstrate the epitaxy growth of Ni80Fe20/Cu superlattices. Upon annealing, the epitaxity of Ni80Fe20/Cu multilayers becomes poor but the local crystallinity in each layer is improved.

  8. Development of a high-resolution soft x-ray (30--1500 eV) beamline at the Advanced Light Source and its use for the study of angle-resolved photoemission extended fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Huff, W R.A. [California Univ., Berkeley, CA (United States). Dept. of Chemistry

    1996-02-01

    ALS Bending magnet beamline 9.3.2 is for high resolution spectroscopy, with circularly polarized light. Fixed included-angle SGM uses three gratings for 30--1500 eV photons; circular polarization is produced by an aperture for selecting the beam above or below the horizontal plane. Photocurrent from upper and lower jaws of entrance slit sets a piezoelectric drive feedback loop on the vertically deflecting mirror for stable beam. End station has a movable platform. With photomeission data from Stanford, structure of c(2{times}2)P/Fe(100) was determined using angle-resolved photoemission extended fine structure (ARPEFS). Multiple-scattering spherical-wave (MSSW) calculations indicate that P atoms adsorb in fourfold hollow sites 1.02A above the first Fe layer. Self-consistent-field X{alpha} scattered wave calculation confirm that the Fe{sub 1}-Fe{sub 2} space is contracted for S/Fe but not for P/Fe; comparison is made to atomic N and O on Fe(100). Final-state effects on ARPEFS curves used literature data from the S 1s and 2p core levels of c(2{times}2)S/Ni(001); a generalized Ramsauer-Townsend splitting is present in the 1s but not 2p data. An approximate method for analyzing ARPEFS data from a non-s initial state using only the higher-{ell} partial wave was tested successfully. ARPEFS data from clean surfaces were collected normal to Ni(111) (3p core levels) and 5{degree} off-normal from Cu(111)(3s, 3p). Fourier transforms (FT) resemble adsorbate systems, showing backscattering signals from atoms up to 4 layers below emitters. 3p FTs show scattering from 6 nearest neighbors in the same crystal layer as the emitters. MSSW calulation indicate that Cu 3p photoemission is mostly d-wave. FTs also indicate double-scattering and single-scattering from laterally distant atoms; calculations indicate that the signal is dominated by photoemission from the first 2 crystal layers.

  9. Structural study on sodium choride by X-ray powder diffraction method

    International Nuclear Information System (INIS)

    The procedure for the crystal structure analysis by means of the X-ray powder diffraction method has been shown using the sodium chloride as a sample. The twelve X-ray diffraction intensity peaks for sodium chloride powder were collected rotating 2 THETA sub(hkl). Bragg angle of X-ray diffractometer from 20 to 160 degrees, in which Cu Ksub(α) radition filtered by nickel had been used. For assigning indices of each reflecting plane, the relationship between lattice parameter and interplanar spacing has been used. This result has shown that sodium chloride is face-centered cubic, space group F 4/m 3-2/m with until cell dimension a = 5.36 A and z = 4. The experimental and theoretical integrated intensities of the reflecting planes are in good agreement with each other. (author)

  10. Angle-resolved soft X-ray magnetic circular dichroism in a monatomic Fe layer facing an MgO(0 0 1) tunnel barrier

    Energy Technology Data Exchange (ETDEWEB)

    Mamiya, K. [Photon Factory, Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Koide, T. [Photon Factory, Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)]. E-mail: tsuneharu.koide@kek.jp; Ishida, Y. [Department of Complexity Science and Engineering, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Osafune, Y. [Department of Complexity Science and Engineering, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Fujimori, A. [Department of Complexity Science and Engineering, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Suzuki, Y. [Graduate School of Engineering Science, Osaka University, 1-3 Toyonaka, Osaka 560-8531 (Japan); NanoElectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Katayama, T. [NanoElectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Yuasa, S. [NanoElectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan)

    2006-11-15

    The electronic and magnetic states of a monatomic Fe(0 0 1) layer directly facing an MgO(0 0 1) tunnel barrier were studied by angle-resolved X-ray magnetic circular dichroism (XMCD) at the Fe L {sub 2,3} edges in the longitudinal (L) and transverse (T) arrangements. A strong XMCD reveals no oxidation of the 1-ML Fe, showing its crucial role in giant tunnel magnetoresistance effects in Fe/MgO/Fe magnetic tunnel junctions. Sum-rule analyses of the angle-resolved XMCD give values of a spin moment, in-plane and out-of-plane orbital and magnetic dipole moments. Argument is given on their physical implication.

  11. Analytical characterization of a new mobile X-ray fluorescence and X-ray diffraction instrument combined with a pigment identification case study

    Energy Technology Data Exchange (ETDEWEB)

    Van de Voorde, Lien, E-mail: lien.vandevoorde@ugent.be [Ghent University, Department of Analytical Chemistry, X-ray Microspectroscopy and Imaging Research Group, Krijgslaan 281 S12, B-9000 Gent (Belgium); Vekemans, Bart [Ghent University, Department of Analytical Chemistry, X-ray Microspectroscopy and Imaging Research Group, Krijgslaan 281 S12, B-9000 Gent (Belgium); Verhaeven, Eddy [Antwerp University, Faculty of Design Sciences, Mutsaardstraat 31, B-2000 Antwerpen (Belgium); Tack, Pieter; De Wolf, Robin; Garrevoet, Jan [Ghent University, Department of Analytical Chemistry, X-ray Microspectroscopy and Imaging Research Group, Krijgslaan 281 S12, B-9000 Gent (Belgium); Vandenabeele, Peter [Ghent University, Department of Archaeology, Archaeometry Research Group, Sint-Pietersnieuwstraat 35, B-9000 Gent (Belgium); Vincze, Laszlo [Ghent University, Department of Analytical Chemistry, X-ray Microspectroscopy and Imaging Research Group, Krijgslaan 281 S12, B-9000 Gent (Belgium)

    2015-08-01

    A new, commercially available, mobile system combining X-ray diffraction and X-ray fluorescence has been evaluated which enables both elemental analysis and phase identification simultaneously. The instrument makes use of a copper or molybdenum based miniature X-ray tube and a silicon-Pin diode energy-dispersive detector to count the photons originating from the samples. The X-ray tube and detector are both mounted on an X-ray diffraction protractor in a Bragg–Brentano θ:θ geometry. The mobile instrument is one of the lightest and most compact instruments of its kind (3.5 kg) and it is thus very useful for in situ purposes such as the direct (non-destructive) analysis of cultural heritage objects which need to be analyzed on site without any displacement. The supplied software allows both the operation of the instrument for data collection and in-depth data analysis using the International Centre for Diffraction Data database. This paper focuses on the characterization of the instrument, combined with a case study on pigment identification and an illustrative example for the analysis of lead alloyed printing letters. The results show that this commercially available light-weight instrument is able to identify the main crystalline phases non-destructively, present in a variety of samples, with a high degree of flexibility regarding sample size and position. - Highlights: • New X-ray fluorescence and X-ray diffraction instrument for non-destructive analysis • Commercially available, mobile system • One of the lightest and most compact of its kind • Characterization, data acquisition and analysis are performed. • Results of measurements on pigment model samples and cultural heritage materials.

  12. Chandra Studies of Unidentified X-ray Sources in the Galactic Bulge

    Science.gov (United States)

    Mori, Hideyuki

    2013-09-01

    We propose to study a complete X-ray sample in the luminosity range of > 10^34 erg s^-1 in the Galactic bulge, including 5 unidentified sources detected in the ROSAT All Sky Survey. Our goal is to obtain a clear picture about X-ray populations in the bulge, by utilizing the excellent Chandra position accuracy leading to unique optical identification together with the X-ray spectral properties. This is a new step toward understanding the formation history of the bulge. Furthermore, because the luminosity range we observe corresponds to a ``missing link'' region ever studied for a neutron star or blackhole X-ray binary, our results are also unique to test accretion disk theories at intermediate mass accretion rates.

  13. Electromigration in integrated circuit interconnects studied by X-ray microscopy

    CERN Document Server

    Schneider, G; Anderson, E; Bates, W; Salmassi, F; Nachimuthu, P; Pearson, A; Richardson, D; Hambach, D; Hoffmann, N; Hasse, W; Hoffmann, K

    2003-01-01

    To study mass transport phenomena in advanced microelectronic devices with X-rays requires penetration of dielectric and Si layers up to 30 mu m thick. X-ray imaging at 1.8 keV photon energy provides a high amplitude contrast between Cu or Al interconnects and dielectric layers and can penetrate through the required thickness. To perform X-ray microscopy at 1.8 keV, a new Ru/Si multilayer was designed for the transmission X-ray microscope XM-1 installed at the Advanced Light Source in Berkeley. The mass flow in a passivated Cu interconnect was studied at current densities up to 10 sup 7 A/cm sup 2. In addition, we demonstrated the high material contrast from different elements in integrated circuits with a resolution of about 40 nm.

  14. Study on the influences of X Ray Scattering on radioscopic inspection

    International Nuclear Information System (INIS)

    This study issued from European project 'Verdict' (Virtual Evaluation and Robust Detection for engine Components non destructive Testing), aimed at developing and evaluating X Ray Non Destructive Method simulation. An qualitative appreciation and quantification for X Ray scattering for modelling (SINDBAD software) was identified. The effect of such radiation on radiogram results in a disturbing blur for interpretation of indications. The method and the results described are innovative in the analysis of X Ray scattering because for aeronautic field, the configurations used with this energy range are breakthrough. The approach followed consists in an experimental and practical method for evaluating scattered radiation on final image issued from the inspection. Experimental tests results confirmed that the influence of scattering radiation are linked to density variation, geometry of parts in the axis of direct radiation and spatial area. This study performed in industrial configurations contributed to improve X Ray scattering understanding. (authors)

  15. Electromigration in integrated circuit interconnects studied by X-ray microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, G. E-mail: gschnei1@gwdg.de; Denbeaux, G.; Anderson, E.; Bates, W.; Salmassi, F.; Nachimuthu, P.; Pearson, A.; Richardson, D.; Hambach, D.; Hoffmann, N.; Hasse, W.; Hoffmann, K

    2003-01-01

    To study mass transport phenomena in advanced microelectronic devices with X-rays requires penetration of dielectric and Si layers up to 30 {mu}m thick. X-ray imaging at 1.8 keV photon energy provides a high amplitude contrast between Cu or Al interconnects and dielectric layers and can penetrate through the required thickness. To perform X-ray microscopy at 1.8 keV, a new Ru/Si multilayer was designed for the transmission X-ray microscope XM-1 installed at the Advanced Light Source in Berkeley. The mass flow in a passivated Cu interconnect was studied at current densities up to 10{sup 7} A/cm{sup 2}. In addition, we demonstrated the high material contrast from different elements in integrated circuits with a resolution of about 40 nm.

  16. Studies of oxide-based thin-layered heterostructures by X-ray scattering methods

    Energy Technology Data Exchange (ETDEWEB)

    Durand, O. [Thales Research and Technology France, Route Departementale 128, F-91767 Palaiseau Cedex (France)]. E-mail: olivier.durand@thalesgroup.com; Rogers, D. [Nanovation SARL, 103 bis rue de Versailles 91400 Orsay (France); Universite de Technologie de Troyes, 10-12 rue Marie Curie, 10010 (France); Teherani, F. Hosseini [Nanovation SARL, 103 bis rue de Versailles 91400 Orsay (France); Andrieux, M. [LEMHE, ICMMOCNRS-UMR 8182, Universite d' Orsay, Batiment 410, 91410 Orsay (France); Modreanu, M. [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland)

    2007-06-04

    Some X-ray scattering methods (X-ray reflectometry and Diffractometry) dedicated to the study of thin-layered heterostructures are presented with a particular focus, for practical purposes, on the description of fast, accurate and robust techniques. The use of X-ray scattering metrology as a routinely working non-destructive testing method, particularly by using procedures simplifying the data-evaluation, is emphasized. The model-independent Fourier-inversion method applied to a reflectivity curve allows a fast determination of the individual layer thicknesses. We demonstrate the capability of this method by reporting X-ray reflectometry study on multilayered oxide structures, even when the number of the layers constitutive of the stack is not known a-priori. Fast Fourier transform-based procedure has also been employed successfully on high resolution X-ray diffraction profiles. A study of the reliability of the integral-breadth methods in diffraction line-broadening analysis applied to thin layers, in order to determine coherent domain sizes, is also reported. Examples from studies of oxides-based thin-layers heterostructures will illustrate these methods. In particular, X-ray scattering studies performed on high-k HfO{sub 2} and SrZrO{sub 3} thin-layers, a (GaAs/AlOx) waveguide, and a ZnO thin-layer are reported.

  17. Polarization dependent interface properties of ferroelectric Schottky barriers studied by soft X-ray absorption spectroscopy

    OpenAIRE

    Kohlstedt, H.; Petraru, A.; Denlinger, M. Meier J.; Guo, J.; Wanli, Y.; A. Scholl; Freelon, B.; Schneller, T.; Waser, R.; Yu, P; Ramesh, R.; Learmonth, T.; Glans, P.-A.; Smith, K. E.

    2008-01-01

    We applied soft X-ray absorption spectroscopy to study the Ti L-edge in ferroelectric capacitors using a modified total electron yield method. The inner photo currents and the X-ray absorption spectra were polarization state dependent. The results are explained on the basis of photo electric effects and the inner potential in the ferroelectric capacitors as a result of back-to-back Schottky barriers superimposed by the potential due to the depolarization field. In general, the presented metho...

  18. X-Ray Photoemission Study of the Oxidation of Hafnium

    International Nuclear Information System (INIS)

    About 20 angstrom of hafnium were deposited on silicon substrates using the electron beam evaporation technique. Two types of samples were investigated. In one type, the substrate was kept at the ambient temperature. After the deposition, the substrate temperature was increased to 100, 200, and 300 degree C. In the other type, the substrate temperature was held fixed at some value during the deposition. For this type, the substrate temperatures used were 100, 200, 300, 400, 500, 550, and 600 degree C. The samples were characterized in situ by the technique of X-ray photoelectron spectroscopy. No trace of elemental hafnium is observed in the deposited overlayer. Also, there is no evidence of any chemical reactivity between the overlayer and the silicon substrate over the temperature range used. The hafnium overlayer shows a mixture of the dioxide and the suboxide. The ratio of the suboxide to dioxide is observed to be more in the first type of samples. The spectral data indicate that hafnium has a strong affinity for oxygen. The overlayer gets completely oxidized to form HfO2 at substrate temperature around 300 degree C for the first type of samples and at substrate temperature greater than 550 degree C for the second type

  19. Microbial biofilm study by synchrotron X-ray microscopy

    Science.gov (United States)

    Pennafirme, S.; Lima, I.; Bitencourt, J. A.; Crapez, M. A. C.; Lopes, R. T.

    2015-11-01

    Microbial biofilm has already being used to remove metals and other pollutants from wastewater. In this sense, our proposal was to isolate and cultivate bacteria consortia from mangrove's sediment resistant to Zn (II) and Cu (II) at 50 mg L-1 and to observe, through synchrotron X-ray fluorescence microscopy (microXRF), whether the biofilm sequestered the metal. The biofilm area analyzed was 1 mm2 and a 2D map was generated (pixel size 20×20 μm2, counting time 5 s/point). The biofilm formation and retention followed the sequence Zn>Cu. Bacterial consortium zinc resistant formed dense biofilm and retained 63.83% of zinc, while the bacterial consortium copper resistant retained 3.21% of copper, with lower biofilm formation. Dehydrogenase activity of Zn resistant bacterial consortium was not negatively affect by 50 mg ml-1 zinc input, whereas copper resistant bacterial consortium showed a significant decrease on dehydrogenase activity (50 mg mL-1 of Cu input). In conclusion, biofilm may protect bacterial cells, acting as barrier against metal toxicity. The bacterial consortia Zn resistant, composed by Nitratireductor spp. and Pseudomonas spp formed dense biofilm and sequestered metal from water, decreasing the metal bioavailability. These bacterial consortia can be used in bioreactors and in bioremediation programs.

  20. X-Ray Photoemission Study of the Oxidation of Hafnium

    Directory of Open Access Journals (Sweden)

    A. R. Chourasia

    2009-01-01

    Full Text Available About 20 Å of hafnium were deposited on silicon substrates using the electron beam evaporation technique. Two types of samples were investigated. In one type, the substrate was kept at the ambient temperature. After the deposition, the substrate temperature was increased to 100, 200, and 300∘C. In the other type, the substrate temperature was held fixed at some value during the deposition. For this type, the substrate temperatures used were 100, 200, 300, 400, 500, 550, and 600∘C. The samples were characterized in situ by the technique of X-ray photoelectron spectroscopy. No trace of elemental hafnium is observed in the deposited overlayer. Also, there is no evidence of any chemical reactivity between the overlayer and the silicon substrate over the temperature range used. The hafnium overlayer shows a mixture of the dioxide and the suboxide. The ratio of the suboxide to dioxide is observed to be more in the first type of samples. The spectral data indicate that hafnium has a strong affinity for oxygen. The overlayer gets completely oxidized to form HfO2 at substrate temperature around 300∘C for the first type of samples and at substrate temperature greater than 550∘C for the second type.

  1. Scanning tunneling microscopy studies of thin foil x-ray mirrors

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Besenbacher, Flemming; Garnaes, Jorgen;

    1990-01-01

    In this paper scanning tunneling microscopy (STM) measurements of x-ray mirrors are presented. The x-ray mirrors are 0.3 mm thick dip-lacquered aluminum foils coated with gold by evaporation, as well as state-of-the-art polished surfaces coated with gold, platinum, or iridium. The measurements....... The results can be used as a guide when selecting the best coating process in the production of x-ray mirrors....... that the microroughness depends on the thickness of the gold layer. The roughness is smallest (~7 to 9 Å) for gold layers between ~100 and ~250Å, and it becomes significantly greater (~10 to 15Å) for gold layers thicker than ~350 Å. With a few exceptions the STM measurements agree well with recent x-ray studies...

  2. Calibrated time-resolved transmission grating spectrometer for the study of ultrafast x-ray sources.

    Science.gov (United States)

    Pelletier, J F; Chaker, M; Kieffer, J C

    1996-01-01

    A transmission grating spectrometer has been coupled to a high-temporal-resolution soft x-ray streak camera for the study of picosecond laser-plasma x-ray sources. A procedure to deconvolve the overlapping contributions of diffraction orders and to calibrate the instrument has been established in order to obtain absolute time-resolved x-ray emission spectra in the 0.1-1.2 keV spectral region. The deconvolution and calibration techniques are presented along with measurements establishing the temporal resolution of this diagnostic at ~2 ps. Examples of calibrated spectra of laser-plasma x-ray sources created by 400 fs laser pulses at intensities of 1018 W/cm2 are also shown. PMID:21307534

  3. The X-Ray Zurich Environmental Study (X-ZENS). II. X-ray Observations of the Diffuse Intragroup Medium in Galaxy Groups

    CERN Document Server

    Miniati, Francesco; Silverman, John D; Carollo, Marcella; Cibinel, Anna; Lilly, Simon J; Schawinski, Kevin

    2014-01-01

    We present the results of a pilot XMM-$Newton$ and $Chandra$ program aimed at studying the diffuse intragroup medium (DIM) of optically-selected nearby groups from the Zurinch ENvironmental Study (ZENS) catalog. The groups are in a narrow mass range about $10^{13}M_\\odot$, a mass scale at which the interplay between the DIM and the group member galaxies is still largely unprobed. X-ray emission from the DIM is detected in the energy band 0.5--2 keV with flux $\\le 10^{-14}$ erg cm$^{-1}$ s$^{-1}$, which is one order of magnitude fainter than for typical ROSAT groups (RASS). For many groups we set upper limits to the X-ray luminosity, indicating that the detections are likely probing the upper envelope of the X-ray emitting groups. We find evidence for our optically selected groups to be under-luminous with respect to predictions from X-ray scaling relations. X-ray mass determinations are in best agreement with those based on the member galaxies bulge luminosity, followed by their total optical luminosity and v...

  4. A study of X-ray and infrared emissions from dusty nonradiative shock waves

    Science.gov (United States)

    Vancura, Olaf; Raymond, John C.; Dwek, Eli; Blair, William P; Long, Knox S.; Foster, Scott

    1994-01-01

    We have constructed models that predict the dynamic evolution and infrared (IR) emission of grains behind nonradiative shock waves. We present a self-consistent treatment of the effect of grain destruction and heating on the ionization structure and X-ray emission of the postshock gas. Incorporating thermal sputtering, collisional heating, and deceleration of grains in the postshock flow, we predict the IR and X-ray fluxes from the dusty plasma as a function of swept-up column density. Heavy elements such as C, O, Mg, S, Si and Fe are initially depleted from the gas phase but are gradually returned as the grains are destroyed. The injected neutral atoms require some time to 'catch up' with the ionization state of the ambient gas. The nonequilibrium ionization state and gradient in elemental abundances in the postshock flow produces characteristic X-ray signatures that can be related to the age of the shock and amount of grain destruction. We study the effects of preshock density and shock velocity on the X-ray and IR emission from the shock. We show that the effects of graindestruction on the X-ray spectra of shock waves are substantial. In particular, temperatures derived from X-ray spectra of middle-aged remnants are likely to be overestimated by approximately 15% if cosmic abundances are assumed. Due to the long timescales for grain destruction in X-ray gases over a wide range of temperatures, we suggest that future X-ray spectra studies of supernova remnants be based on depleted abundances instead of cosmic abundances. Our model predictions agree reasonably well with IRAS and Einstein IPC observations of the Cygnus Loop.

  5. Turbulent Pitch-angle Scattering and Diffusive Transport of Hard X-Ray-producing Electrons in Flaring Coronal Loops

    Science.gov (United States)

    Kontar, Eduard P.; Bian, Nicolas H.; Emslie, A. Gordon; Vilmer, Nicole

    2014-01-01

    Recent observations from RHESSI have revealed that the number of non-thermal electrons in the coronal part of a flaring loop can exceed the number of electrons required to explain the hard X-ray-emitting footpoints of the same flaring loop. Such sources cannot, therefore, be interpreted on the basis of the standard collisional transport model, in which electrons stream along the loop while losing their energy through collisions with the ambient plasma; additional physical processes, to either trap or scatter the energetic electrons, are required. Motivated by this and other observations that suggest that high-energy electrons are confined to the coronal region of the source, we consider turbulent pitch-angle scattering of fast electrons off low-frequency magnetic fluctuations as a confinement mechanism, modeled as a spatial diffusion parallel to the mean magnetic field. In general, turbulent scattering leads to a reduction of the collisional stopping distance of non-thermal electrons along the loop, and hence to an enhancement of the coronal hard X-ray source relative to the footpoints. The variation of source size L with electron energy E becomes weaker than the quadratic behavior pertinent to collisional transport, with the slope of L(E) depending directly on the mean free path λ associated with the non-collisional scattering mechanism. Comparing the predictions of the model with observations, we find that λ ~ (108-109) cm for ~30 keV, less than the length of a typical flaring loop and smaller than, or comparable to, the size of the electron acceleration region.

  6. Turbulent pitch-angle scattering and diffusive transport of hard X-ray-producing electrons in flaring coronal loops

    Energy Technology Data Exchange (ETDEWEB)

    Kontar, Eduard P.; Bian, Nicolas H. [School of Physics and Astronomy, The University of Glasgow, G12 8QQ (United Kingdom); Emslie, A. Gordon [Department of Physics and Astronomy, Western Kentucky University, Bowling Green, KY 42101 (United States); Vilmer, Nicole, E-mail: eduard@astro.gla.ac.uk, E-mail: emslieg@wku.edu [LESIA Observatoire de Paris, CNRS, UPMC, Universite Paris Diderot, 5 place Jules Janssen, 92195 Meudon Cedex (France)

    2014-01-10

    Recent observations from RHESSI have revealed that the number of non-thermal electrons in the coronal part of a flaring loop can exceed the number of electrons required to explain the hard X-ray-emitting footpoints of the same flaring loop. Such sources cannot, therefore, be interpreted on the basis of the standard collisional transport model, in which electrons stream along the loop while losing their energy through collisions with the ambient plasma; additional physical processes, to either trap or scatter the energetic electrons, are required. Motivated by this and other observations that suggest that high-energy electrons are confined to the coronal region of the source, we consider turbulent pitch-angle scattering of fast electrons off low-frequency magnetic fluctuations as a confinement mechanism, modeled as a spatial diffusion parallel to the mean magnetic field. In general, turbulent scattering leads to a reduction of the collisional stopping distance of non-thermal electrons along the loop, and hence to an enhancement of the coronal hard X-ray source relative to the footpoints. The variation of source size L with electron energy E becomes weaker than the quadratic behavior pertinent to collisional transport, with the slope of L(E) depending directly on the mean free path λ associated with the non-collisional scattering mechanism. Comparing the predictions of the model with observations, we find that λ ∼ (10{sup 8}-10{sup 9}) cm for ∼30 keV, less than the length of a typical flaring loop and smaller than, or comparable to, the size of the electron acceleration region.

  7. 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.

  8. Soft x-ray studies of plasma-focus pinch structures in PF-1000U experiments

    Science.gov (United States)

    Sadowski, M. J.; Paduch, M.; Skladnik-Sadowska, E.; Surala, W.; Zaloga, D.; Miklaszewski, R.; Zielinska, E.; Tomaszewski, K.

    2015-10-01

    This work reports on recent experiments performed at the modernized PF-1000U plasma-focus facility. In contrast to earlier studies the main attention was focussed on measurements of the soft x-ray emission. Detailed time-integrated x-ray measurements, carried out using filtered pinhole cameras with sensitive x-ray films, are presented and analysed. The fine structure of the collapsing current sheath and dense pinch column is investigated. Observations of ‘plasma filaments’ are discussed and compared with those from the old POSEIDON facility. New results are time-integrated x-ray images of PF-1000U discharges with additional gas puffing, which in many cases show distinct plasma filaments and/or ‘hot spots’ formed inside the dense pinch column. The formation of such ‘hot-spots’ is explained by necking and breaking of the plasma filaments. Results of time-resolved x-ray measurements, performed outside the experimental chamber by means of scintillation probes, and inside with PIN-diodes placed behind pinholes and absorption filters, are also presented Time-resolved measurements, carried out using an old XUV framing-camera and a new soft x-ray four-frame camera (SXRFFC), are also presented and discussed. Correlations of the time-integrated x-ray images (of plasma filaments and hot spots) with time-resolved x-ray signals are discussed. The hypothesis that plasma-current filaments appear in almost all PF-type discharges is supported by pictures of radial erosion tracks on the anode front-plate after many discharges.

  9. Recent Advances in Computational Studies of Charge Exchange X-ray Emission

    Science.gov (United States)

    Cumbee, Renata

    2016-06-01

    Interest in astrophysical sources of charge exchange (CX) has grown since X-ray emission from comet Hyakutake was first observed, the origin of which is primarily due to CX processes between neutral species in the comet’s atmosphere and highly charged ions from the solar wind. More recent observations have shown that CX may have a significant contribution to the X-ray emission spectra of a wide variety of environments within our solar system including solar wind charge exchange (SWCX) with neutral gases in the heliosphere and in planetary atmospheres, as well as beyond the solar system in galaxy clusters, supernova remnants, and star forming galaxies.While the basic process of CX has been studied for many decades, the reliability of the existing data is not uniform, and the coverage of the astrophysically important projectile and target combinations and collisional velocities is insufficient. The need for reliable and robust CX X-ray emission models will only be amplified with the with the high resolution X-ray spectra expected from the soft X-ray imaging calorimeter spectrometer (SXS) onboard the Hitomi X-ray observatory. In this talk, I will discuss recent advances in theoretical CX cross sections and X-ray modeling with a focus on CX diagnostics. The need for experimental X-ray spectra and cross sections for benchmarking current theory will also be highlighted. This work was performed in collaboration with David Lyons, Patrick Mullen, David Schultz, Phillip Stancil, and Robin Shelton. Work at UGA was partially supported by NASA grant NNX09AC46G.

  10. Shadowing the soft x-ray background by infrared cirrus: A study of selected regions

    Science.gov (United States)

    Wang, Q. Daniel; Yu, Ka Chun

    1995-01-01

    Using the ROSAT and IRAS data achieves, we studied shadows in the diffuse 0.25 keV background toward infrared cirrus clouds to infer the distribution of the hot interstellar medium (ISM). Surprisingly, we found that anticorrelation between infrared emission from cirrus clouds and background x-ray intensity was present in all five galactic latitude (b approx. greater than 25 deg) fields that we selected. In two fieds, the anticorrelation is more than 30% deep, and shows particularly convincing evidence that they are due to x-ray absorption by the clouds. Assuming an average density for the local x-ray-emitting gas (T approximately 10(exp 6) K), we estimated the minimum distances to the clouds based on our best-fit x-ray intensities originating in front of the clouds. These distances are in the range of 60 to 160 pc. Therefore, we conclude that there are a considerable number of degree-size, x-ray-absorbing gas clouds at approximately 10(exp 2) pc and that large amounts of x-ray-emitting gas exist in regions beyonds these clouds.

  11. Radiation effects and metalloproteins studied by x-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wurzbach, J.A.

    1975-07-01

    X-ray photoelectron spectroscopy (XPS) is used to study the bonding structure at the iron site of cytochrome c and the bonding of rare earth ions to the phosphate oxygens of ATP. Radiation effects are studied on several amino acid and simple peptide model systems. The emission spectrum of the x-ray source is calculated from literature references. The distributions of photon energy as a function of photon frequency and as a function of take-off angle are obtained. From these distributions, the radiation dose absorbed by an organic sample is found to be 10/sup 6/ rads/sec. The C 1s and N 1s spectra of amino acids and peptides are studied to characterize an internal reference standard for protein XPS spectra. Samples of native cytochrome c prepared from solutions of pH 1.5, 3, 7, and 11 are studied. Control samples include porphyrin cytochrome c (PCC), the metal free analogue of the native protein, and microperoxidase (MP), a mixture of heme peptides derived from the peptic digestion of cytochrome c. These samples show two S 2p peaks. The first peak has a binding energy (BE) of 163 eV, which corresponds to the S containing amino acids; the second peak is shifted to 167 eV. This large shift may be the result of Fe-S binding, or oxidation, or both. Low spin ferricytochrome c and ferri-MP were found to have Fe 3p BE's that are unusually low (51 eV) compared to other ferric compounds (54 to 58 eV) and even Fe metal (53 eV). X-ray crystal structures of these compounds show that low spin heme Fe lies in the porphyrin plane; while, high spin heme Fe is displaced above the plane. The N 1s and P 2p spectra of ATP show no change except slight broadening when Nd/sup 3 +/ is substituted for Na/sup +/. Thus, there is no inconsistency with proposals that rare earth ions might be useful as substitutes for alkali metal ions and alkaline earth ions in proteins.

  12. Radiation effects and metalloproteins studied by x-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    X-ray photoelectron spectroscopy (XPS) is used to study the bonding structure at the iron site of cytochrome c and the bonding of rare earth ions to the phosphate oxygens of ATP. Radiation effects are studied on several amino acid and simple peptide model systems. The emission spectrum of the x-ray source is calculated from literature references. The distributions of photon energy as a function of photon frequency and as a function of take-off angle are obtained. From these distributions, the radiation dose absorbed by an organic sample is found to be 106 rads/sec. The C 1s and N 1s spectra of amino acids and peptides are studied to characterize an internal reference standard for protein XPS spectra. Samples of native cytochrome c prepared from solutions of pH 1.5, 3, 7, and 11 are studied. Control samples include porphyrin cytochrome c (PCC), the metal free analogue of the native protein, and microperoxidase (MP), a mixture of heme peptides derived from the peptic digestion of cytochrome c. These samples show two S 2p peaks. The first peak has a binding energy (BE) of 163 eV, which corresponds to the S containing amino acids; the second peak is shifted to 167 eV. This large shift may be the result of Fe-S binding, or oxidation, or both. Low spin ferricytochrome c and ferri-MP were found to have Fe 3p BE's that are unusually low (51 eV) compared to other ferric compounds (54 to 58 eV) and even Fe metal (53 eV). X-ray crystal structures of these compounds show that low spin heme Fe lies in the porphyrin plane; while, high spin heme Fe is displaced above the plane. The N 1s and P 2p spectra of ATP show no change except slight broadening when Nd3+ is substituted for Na+. Thus, there is no inconsistency with proposals that rare earth ions might be useful as substitutes for alkali metal ions and alkaline earth ions in proteins

  13. Combination of Raman, infrared, and X-ray energy-dispersion spectroscopies and X-ray d diffraction to study a fossilization process

    International Nuclear Information System (INIS)

    X-ray diffraction was combined with X-ray energy-dispersion, Fourier-transform infrared, and Raman spectroscopies to study the fossilization of a Cretaceous specimen of the plant Brachyphyllum castilhoi, a fossil from the Ipubi Formation, in the Araripe Sedimentary Basin, Northeastern Brazil. Among the possible fossilization processes, which could involve pyrite, silicon oxide, calcium oxide, or other minerals, we were able to single out pyritization as the central mechanism producing the fossil, more than 100 million years ago. In addition to expanding the knowledge of the Ipubi Formation, this study shows that, when combined with other experimental techniques, Raman spectroscopy is a valuable tool at the paleontologist's disposal. (author)

  14. The Mn₄Ca photosynthetic water-oxidation catalyst studied by simultaneous X-ray spectroscopy and crystallography using an X-ray free-electron laser.

    Science.gov (United States)

    Tran, Rosalie; Kern, Jan; Hattne, Johan; Koroidov, Sergey; Hellmich, Julia; Alonso-Mori, Roberto; Sauter, Nicholas K; Bergmann, Uwe; Messinger, Johannes; Zouni, Athina; Yano, Junko; Yachandra, Vittal K

    2014-07-17

    The structure of photosystem II and the catalytic intermediate states of the Mn₄CaO₅ cluster involved in water oxidation have been studied intensively over the past several years. An understanding of the sequential chemistry of light absorption and the mechanism of water oxidation, however, requires a new approach beyond the conventional steady-state crystallography and X-ray spectroscopy at cryogenic temperatures. In this report, we present the preliminary progress using an X-ray free-electron laser to determine simultaneously the light-induced protein dynamics via crystallography and the local chemistry that occurs at the catalytic centre using X-ray spectroscopy under functional conditions at room temperature.

  15. Small angle X-ray scattering studies to access the influence of bovine serum albumin (BSA) and carbonic anhydrase (Boca) on the size and interaction among Aerosol-O T reversed micelles as a function of the micellar hydration degree

    International Nuclear Information System (INIS)

    Full text: Reversed micelles (RMs) of AOT (sodium bis-2-ethylhexyl sulfosuccinate) has constitute an efficient system to investigate membrane interaction and physical chemical behavior of short biologically active peptides, proteins and enzymes in water controlled environment and apolar medium. Information may be obtained from protein-membrane interaction, including solubilization, binding location, conformational changes, activity size droplet-dependent, and changes in the properties of RM environment, useful in studies in biocatalysis and bioseparation systems [1]. In this work, changes in the structural features and interactive forces among AOT RMs in hexane were monitored in several stages of micellar hydration W (= [buffer]/[0.1M AOT]), and in the presence of BSA (66.5 kDa) and BCA (30 Kda), by SAXS. The interactive forces between the RMs with proteins were analyzed within the framework of repulsion and attractive interaction potentials through the pairing stick hardsphere (PSHS) model [2]. In this way, the spherical core radius to the system of pure AOT RMs at W = 4, 10, 20 and 30 were respectively 15, 22, 33 and 43 A (20% of polydispersity), evaluated from the particle form factor P(q) modeling [1]. The PSHS analysis from SAXS curves of AOT RMs with BSA and BCA at smaller droplets size of 4 and 10, showed, respectively, an interplay between attractive and repulsive interactions between the micelles (attractive component in S(q) was predominant) with the preservation of the discrete RM radius in the presence of protein. On the other hand, for protein confined in the bigger RM droplet size with W=30, the attractive inter micellar forces were of minor importance for BSA and the appearing of a predominant repulsive hard sphere component in SAXS curves accompanied by a decreasing of the micellar radius to 36 A were detected. For BCA, however, at higher W (30), a phase separation was observed probably associated to the formation of unstable large BCA aggregates

  16. Conceptual study of moderately coupled plasmas and experimental comparison of laboratory x-ray sources

    Energy Technology Data Exchange (ETDEWEB)

    Li, C. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center

    1993-12-01

    In this thesis the fundamental concepts of moderately coupled plasmas, for which 2{approx_lt}ln{Lambda}{sub b}{approx_lt}10, are, for the first time, presented. This investigation is motivated because neither the conventional Fokker-Planck approximation [for weakly coupled plasmas (ln{Lambda}{sub b}{approx_lt}10)] nor the theory of dielectric response with correlations for strongly coupled plasmas (ln{Lambda}{sub b}{approx_lt}1) has satisfactorily addressed this regime. Specifically, herein the standard Fokker-Planck operator for Coulomb collisions has been modified to include hitherto neglected terms that are directly associated with large-angle scattering. In addition a reduced electron-ion collision operator has been calculated that, for the first time, manifests 1/ln{Lambda}{sub b} corrections. Precise calculations of some relaxation rates and crude calculations of electron transport coefficients have been made. As one of major applications of the modified Fokker-Planck equation, the stopping powers and {rho}R have been calculated for charged fusion products ({alpha}`s, {sup 3}H, {sup 3}He) and hot electrons interacting with plasmas relevant to inertial confinement fusion. In the second major topic of this thesis, advances made in the area of laboratory x-ray sources are presented. First, and most importantly, through the use a Cockcroft-Walton linear accelerator, a charged particle induced x-ray emission (PIXE) source has been developed. Intense line x radiation (including K-, L-, M-, and N-lines) with wavelengths from 0.5 {angstrom} to 111 {angstrom} have been successfully produced. Second, a new high intensity electron-beam x-ray generator has also been developed, and it has been used with advantage in the soft x-ray region ( < 3 keV). Finally, a direct comparisons of both sources (PIXE and electron-beam x-ray sources) to a commercially available radioactive {alpha} fluorescent x-ray source has been made.

  17. First observation of soft x-ray induced phase transition of RbMn[Fe(CN)6] studied by Fe L-edge x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kitajima, Yoshinori [Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Ishiji, Kotaro [Kyushu Synchrotron Light Research Center, 8-7 Yayoigaoka, Tosu, Saga 841-0005 (Japan); Matsuda, Tomoyuki; Tokoro, Hiroko; Ohkoshi, Shin-ichi [Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Iwazumi, Toshiaki, E-mail: yoshinori.kitajima@kek.j [Department of Mathematical Sciences, School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531 (Japan)

    2009-02-01

    Temperature-induced and photoinduced phase transition in a ferromagnet Rb{sub 0.94}Mn[Fe(CN){sub 6}]{sub 0.98}0.4H{sub 2}O was studied by X-ray absorption spectroscopy at Fe L-edge. Compared with spectra of K{sub 4}[Fe(CN){sub 6}] and K{sub 3}[Fe(CN){sub 6}] as standards for Fe(II) and Fe(III), temperature-induced phase transition is clearly shown. At 43 K, phase transition induced by the soft X-rays was firstly observed.

  18. Electronic Structures of Uranium Compounds Studied by Soft X-ray Photoelectron Spectroscopy

    Science.gov (United States)

    Fujimori, Shin-ichi; Takeda, Yukiharu; Okane, Tetsuo; Saitoh, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Haga, Yoshinori; Yamamoto, Etsuji; Ōnuki, Yoshichika

    2016-06-01

    The electronic structures of uranium-based compounds have been studied by photoelectron spectroscopy with soft X-ray synchrotron radiation. Angle-resolved photoelectron spectroscopy with soft X-rays has made it possible to directly observe their bulk band structures and Fermi surfaces. It has been shown that the band structures and Fermi surfaces of itinerant compounds such as UB2, UN, and UFeGa5 are quantitatively described by a band-structure calculation treating all U 5f electrons as itinerant. Furthermore, the overall electronic structures of heavy-fermion compounds such as UPd2Al3, UNi2Al3, and URu2Si2 are also explained by a band-structure calculation, although some disagreements exist, which might originate from the electron correlation effect. This suggests that the itinerant description of U 5f states is an appropriate starting point for the description of their electronic structures. The situation is similar for ferromagnetic superconductors such as UGe2, URhGe, UCoGe, and UIr, although the complications from their low-symmetry crystal structures make it more difficult to describe their detailed electronic structures. The local electronic structures of the uranium site have been probed by core-level photoelectron spectroscopy with soft X-rays. The comparisons of core-level spectra of heavy-fermion compounds with typical itinerant and localized compounds suggest that the local electronic structures of most itinerant and heavy-fermion compounds are close to the U 5f3 configuration except for UPd2Al3 and UPt3. The core-level spectrum of UPd2Al3 has similarities to those of both itinerant and localized compounds, suggesting that it is located at the boundary between the itinerant and localized states. Moreover, the spectrum of UPt3 is very close to that of the localized compound UPd3, suggesting that it is nearly localized, although there are narrow quasi-particle bands in the vicinity of EF.

  19. An X-ray and Neutron Scattering Study of the Formation of Core-Shell Type Polyoxometalates

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Panchao; Wu, Bin; Mamontov, Eugene; Daemen, Luke L.; Cheng, Yongqiang; Li, Tao; Seifert, Soenke; Hong, Kunlun; Bonnesen, Peter V.; Keum, Jong Kahk; Ramirez-Cuesta, Anibal J.

    2016-03-02

    A typical type of core-shell polyoxometalates can be obtained through the Keggin-type polyoxometalatetemplated growth of a layer of spherical shell structure of {Mo72Fe30}. Small angle X-ray scattering is used to study the structural features and stability of the core-shell structures in aqueous solutions. Timeresolved small angle X-ray scattering is applied to monitor the synthetic reactions and a three-stage formation mechanism is proposed to describe the synthesis of the core-shell polyoxometalates based on the monitoring results. New protocols have been developed by fitting the X-ray data with customed physical models, which provide more convincing, objective, and completed data interpretation. Quasielastic and inelastic neutron scattering are used to probe the dynamics of water molecules in the core-shell structures and two different types of water molecules, the confined and structured water, are observed. These water molecules play an important role in bridging core and shell structures and stabilizing the cluster structures.

  20. 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.

  1. Development of an x-ray beam line at the NSLS for studies in materials science using x-ray absorption spectroscopy: Annual progress report

    International Nuclear Information System (INIS)

    Although only in operation since May, 1985, the X-11 participation research team (PRT) at the NSLS has already demonstrated that it is one of the leading centers of x-ray absorption spectroscopy (XAS). During this time, results have been obtained and programs initiated in a number of areas, for example: interfaces, including deposited metal-metal and metal-semiconductor systems, multilayers and ion implanted layers; electrochemical systems, including Pt electrode fuel cells, Ni oxide battery electrodes, conducting polymers, passivation and corrosion; catalysts, including highly-dispersed supported metal catalysts and zeolite systems; quasi-crystals, heavy fermion systems, uranium and neptunium compounds, rare gas clusters, disordered metals and semiconductors, ferroelectric transition; and, biological systems and related models, including synthetic porphyrins and a number of metalloproteins. In concert with these scientific results have been a number of developments involving the technique itself. These include implementation of unique optical systems on both the A and B lines for optical performance over their designed energy ranges, advances in experimental capability, particular in glancing angle studies, optimization of ion chambers for surface studies, the improvement of electron yield detectors, and improved software for data acquisition and analysis. This report emphasizes some of the research highlights and significant developments of our PRT which occurred during the past year. A detailed bibliography of papers and talks resulting from work done at our beamline and the progress reports for our PRT which were in the 1985 NSLS Annual Report are appended

  2. Shift-and-add tomosynthesis of a finger joint by X-ray dark-field imaging: Difference due to tomographic angle

    International Nuclear Information System (INIS)

    A tomogram of a finger joint showing articular cartilage was generated based on X-ray dark-field imaging (XDFI) using the shift-and-add tomosynthesis algorithm. The experiment was performed at beamline 14B of the Photon Factory in Tsukuba, Japan, using synchrotron X-rays from a vertical wiggler. The incident X-ray energy was 36.0 keV. The X-ray optics for XDFI comprised two Si crystals: an asymmetric cut Si (2 2 0) monochromator-collimator and a 1.1-mm thick Si (2 2 0) Laue-case analyzer. The object was an intact cadaveric proximal interphalangeal joint fixed in formalin. Raw projection data were acquired by XDFI in a total of 41 views through an angle of 20 deg. in 0.5 deg. increments. The object and detector were synchronously rotated such that the fulcrum plane in the object and detector plane remained parallel. The X-ray dose for one piece of raw projection data was set to one-eleventh of that for one standard projection image by XDFI. Eleven views through an angle of 10 deg. in increments of 1 deg. of all 41 appropriately shifted raw projection data were added to produce arbitrary tomograms parallel to the fulcrum plane. We obtained a clear tomogram of the finger joint including the articular cartilage with the moderate artifact peculiar to tomosynthesis. Consequently, arbitrary tomograms can be obtained for the same X-ray dose as that received for one standard projection image by XDFI. The fact that an inner structure such as articular cartilage, which is invisible to conventional X-ray imaging methods, has been visualized on a tomogram with preserved refraction-enhanced contrast, is of considerable significance to clinical medicine

  3. A Chandra X-ray Study of NGC 1068: II. The Luminous X-ray Source Population

    OpenAIRE

    Smith, David A.; Wilson, Andrew S.

    2003-01-01

    We present an analysis of the compact X-ray source population in the Seyfert~2 galaxy NGC 1068, imaged with Chandra. We find a total of 84 compact sources, of which 66 are projected onto the galactic disk of NGC 1068. Spectra of the brightest sources have been modeled with both multi-color disk blackbody and power-law models. The power-law model provides the better description of the spectrum for most of these sources. Five sources have 0.4-8 keV intrinsic luminosities greater than 10^{39} er...

  4. Dental x-rays and the risk of thyroid cancer: A case-control study

    Energy Technology Data Exchange (ETDEWEB)

    Memon, Anjum (Div. of Primary Care and Public Health, Brighton and Sussex Medical School (United Kingdom)), E-mail: a.memon@bsms.ac.uk; Godward, Sara (Dept. of Public Health and Primary Care, Univ. of Cambridge (United Kingdom)); Williams, Dillwyn (Thyroid Carcinogenesis Research Group, Strangeways Research Laboratories, Univ. of Cambridge (United Kingdom)); Siddique, Iqbal (Dept. of Medicine, Faculty of Medicine, Kuwait Univ. (Kuwait)); Al-Saleh, Khalid (Kuwait Cancer Control Centre, Ministry of Health (Kuwait))

    2010-05-15

    The thyroid gland is highly susceptible to radiation carcinogenesis and exposure to high-dose ionising radiation is the only established cause of thyroid cancer. Dental radiography, a common source of low-dose diagnostic radiation exposure in the general population, is often overlooked as a radiation hazard to the gland and may be associated with the risk of thyroid cancer. An increased risk of thyroid cancer has been reported in dentists, dental assistants, and x-ray workers; and exposure to dental x-rays has been associated with an increased risk of meningiomas and salivary tumours. Methods. To examine whether exposure to dental x-rays was associated with the risk of thyroid cancer, we conducted a population-based case-control interview study among 313 patients with thyroid cancer and a similar number of individually matched (year of birth +- three years, gender, nationality, district of residence) control subjects in Kuwait. Results. Conditional logistic regression analysis, adjusted for other upper-body x-rays, showed that exposure to dental x-rays was significantly associated with an increased risk of thyroid cancer (odds ratio = 2.1, 95% confidence interval: 1.4, 3.1) (p=0.001) with a dose-response pattern (p for trend <0.0001). The association did not vary appreciably by age, gender, nationality, level of education, or parity. Discussion. These findings, based on self-report by cases/controls, provide some support to the hypothesis that exposure to dental x-rays, particularly multiple exposures, may be associated with an increased risk of thyroid cancer; and warrant further study in settings where historical dental x-ray records may be available.

  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. 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.

  7. Soft-x-ray fluorescence study of buried silicides in antiferromagnetically coupled Fe/Si multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Carlisle, J.A.; Chaiken, A.; Michel, R.P. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Multilayer films made by alternate deposition of two materials play an important role in electronic and optical devices such as quantum-well lasers and x-ray mirrors. In addition, novel phenomena like giant magnetoresistance and dimensional crossover in superconductors have emerged from studies of multilayers. While sophisticated x-ray techniques are widely used to study the morphology of multilayer films, progress in studying the electronic structure has been slower. The short mean-free path of low-energy electrons severely limits the usefulness of photoemission and related electron free path of low-energy electrons severely limit spectroscopies for multilayer studies. Soft x-ray fluorescence (SXF) is a bulk-sensitive photon-in, photon-out method to study valence band electronic states. Near-edge x-ray absorption fine-structure spectroscopy (NEXAFS) measured with partial photon yield can give complementary bulk-sensitive information about unoccupied states. Both these methods are element-specific since the incident x-ray photons excite electrons from core levels. By combining NEXAFS and SXF measurements on buried layers in multilayers and comparing these spectra to data on appropriate reference compounds, it is possible to obtain a detailed picture of the electronic structure. Results are presented for a study of a Fe/Si multilayer system.

  8. Ray tracing flux calculation for the small and wide angle x-ray scattering diffraction station at the SESAME synchrotron radiation facility

    International Nuclear Information System (INIS)

    The calculation for the optics of the synchrotron radiation small and wide angle x-ray scattering beamline, currently under construction at SESAME is described. This beamline is based on a cylindrically bent germanium (111) single crystal with an asymmetric cut of 10.5 deg., followed by a 1.2 m long rhodium coated plane mirror bent into a cylindrical form. The focusing properties of bent asymmetrically cut crystals have not yet been studied in depth. The present paper is devoted to study of a particular application of a bent asymmetrically cut crystal using ray tracing simulations with the SHADOW code. These simulations show that photon fluxes of order of 1.09x1011 photons/s will be available at the experimental focus at 8.79 keV. The focused beam dimensions will be 2.2 mm horizontal full width at half maximum (FWHM) by 0.12 mm vertical (FWHM).

  9. Application of the X-ray fluorescence analysis and X-ray diffraction in geochemical studies of the Pleistocene tills from Holy Cross Mountains

    Science.gov (United States)

    Kubala-Kukuś, A.; Ludwikowska-Kȩdzia, M.; Banaś, D.; Braziewicz, J.; Majewska, U.; Pajek, M.; Wudarczyk-Moćko, J.

    2013-12-01

    X-ray fluorescence analysis methods (wavelength dispersive X-ray fluorescence analysis (WDXRF) and total reflection X-ray fluorescence (TXRF)) and X-ray powder diffraction (XRPD) have been applied in complementary geochemical studies of the Pleistocene till samples. The XRPD technique gave information about the mineral composition of the analyzed samples while the WDXRF and TXRF studies allowed the fast elemental analysis. The till samples were collected from different regions of Holy Cross Mountains (located in central Poland) which are still not unambiguously described in the context of the geochemical studies of the Quaternary sediments. The analysis was concentrated on the geochemical composition of the till samples both for materials occurring on the surface (characterized by continuous weathering processes) and for samples taken from core borehole. The overriding purpose of these studies is determination of the local lithotype of the tills and its lithologic and petrographic diagnostic properties, including the chemical composition of clay and minerals found in the clay. In the presented work the experimental sets up, sample preparation procedure and measurements programme will be discussed in details. Finally, the elemental and mineral compositions will be presented for studied different groups of the samples.

  10. An X-ray study of the dipping low mass X-ray binary XB 1323-619

    CERN Document Server

    Balucinska-Church, M; Oosterbroek, T; Segreto, A; Morley, R E; Parmar, A N

    1999-01-01

    During a BeppoSAX observation of the low-mass X-ray binary dip source XB 1323-619 a total of 10 type I X-ray bursts and parts of 12 intensity dips were observed. During non-bursting, non-dipping intervals, the 1-150 keV BeppoSAX spectrum can be modelled by a cutoff power-law with a photon index of 1.48 +/- 0.01, a cutoff energy of 44.1 +5.1/-4.4 keV together with a blackbody with kT of 1.77 +/- 0.25 keV contributing ~15% of the 2-10 keV flux. Absorption equivalent to 3.88 +/- 0.16x10^22 H atom cm^(-2) is required. The dips repeat with a period of 2.938 +/- 0.020 hr and span 40% of the orbital cycle. During dips the maximum reduction in 2-10 keV intensity is ~65%. The spectral changes during dips are complex and cannot be modelled by a simple absorber because of the clear presence of part of the non-dip spectrum which is not absorbed. Spectral evolution in dipping can be well modelled by progressive covering of the cutoff power-law component which must be extended, plus rapid absorption of the point-source bla...

  11. Spectroscopic and X-ray Diffraction Study of Structural Disorder in Cryomilled and Amorphous Griseofulvin

    Energy Technology Data Exchange (ETDEWEB)

    A Zarow; B Zhou; X Wang; R Pinal; Z Iqbal

    2011-12-31

    Structural disorder induced by cryogenic milling and by heating to the amorphous phase in the active pharmaceutical ingredient Griseofulvin has been studied using Raman spectroscopy, X-ray powder diffraction (XRPD), and fluorescence spectroscopy. A broad, exciting-frequency-independent scattering background in the Raman spectra and changes in intensities and splitting of some of the Raman lines due to lattice and molecular modes have been observed. In the cryomilled samples this strong background is deconvoluted into two components: one due to lattice disorder induced by cryomilling and the other due to Mie scattering from nanosized crystallites. A single-component background scattering attributed to lattice disorder is seen in the Raman spectrum of the amorphous sample. Fluorescence measurements showed an intrinsic fluorescence signal in as-received Griseofulvin that does not correspond to the inelastic background in the Raman spectra and, moreover, decreases in intensity upon cryomilling, thus excluding an assignment of the Raman background intensity to impurity- or molecular-defect-induced fluorescence. Wide-angle XRPD measurements on cryomilled Griseofulvin shows a broad two-component background consistent with the background-scattering component in the Raman data associated with lattice disorder, but at longer correlation lengths. Persistence of this disorder to even longer lengths is evident in small-angle synchrotron XRPD data on micronized Griseofulvin taken as a function of temperature from the crystalline to the amorphous phase.

  12. Ordered mesoporous silica and alumina thin films studied by X-ray scattering

    Science.gov (United States)

    Klotz, M.; Idrissi-Kandri, N.; Ayral, A.; van der Lee, A.; Guizard, C.

    2002-07-01

    The use of X-ray techniques for the characterisation of ordered mesoporous films is demonstrated. Both silica and alumina thin layers with an ordered mesoporosity are studied using low-angle diffraction and grazing incidence reflectometry. It is shown how the internal structure evolves upon drying and how texture can be easily detected using a two-circle diffractometer. The reflectometry data are correlated with results from nitrogen adsorption/desorption experiments. Nous montrons comment les techniques de rayons-X peuvent être utilisées pour la caractérisation des couches à mésoporosité ordonnée. Des couches minces de silice et d'alumine à mésoporosité ordonnée ont été étudiées par diffraction aux petits angles et réflectométrie en incidence rasante. Il est montré comment la structure interne évolue au cours du séchage et comment la texture peut être analysée en utilisant un diffractomètre deux-cercles. Les données de réflectométrie sont corrélées avec les résultats obtenus par des mesures d'adsorption-désorption d'azote.

  13. X-ray radiation damage studies and design of a silicon pixel sensor for science at the XFEL

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiaguo

    2013-06-15

    Experiments at the European X-ray Free Electron Laser (XFEL) require silicon pixel sensors which can withstand X-ray doses up to 1 GGy. For the investigation of Xray radiation damage up to these high doses, MOS capacitors and gate-controlled diodes built on high resistivity n-doped silicon with crystal orientations left angle 100 right angle and left angle 111 right angle produced by four vendors, CiS, Hamamatsu, Canberra and Sintef have been irradiated with 12 keV X-rays at the DESY DORIS III synchrotron-light source. Using capacitance/ conductance-voltage, current-voltage and thermal dielectric relaxation current measurements, the densities of oxide charges and interface traps at the Si-SiO{sub 2} interface, and the surface-current densities have been determined as function of dose. Results indicate that the dose dependence of the oxide-charge density, the interface-trap density and the surface-current density depend on the crystal orientation and producer. In addition, the influence of the voltage applied to the gates of the MOS capacitor and the gate-controlled diode during X-ray irradiation on the oxide-charge density, the interface-trap density and the surface-current density has been investigated at doses of 100 kGy and 100 MGy. It is found that both strongly depend on the gate voltage if the electric field in the oxide points from the surface of the SiO{sub 2} to the Si-SiO{sub 2} interface. To verify the long-term stability of irradiated silicon sensors, annealing studies have been performed at 60 C and 80 C on MOS capacitors and gate-controlled diodes irradiated to 5 MGy as well, and the annealing kinetics of oxide charges and surface current were determined. Moreover, the macroscopic electrical properties of segmented sensors have slao been investigated as function of dose. It is found that the defects introduced by X-rays increase the full depletion voltage, the surface leakage current and the inter-electrode capacitance of the segmented sensor. An

  14. X-ray study of a SODART flight telescope using the expanded beam x-ray optics beamline at the Daresbury synchrotron

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Hornstrup, Allan; Frederiksen, P. K.;

    1995-01-01

    The on- and off-axis imaging properties of the first of two SODART flight telescopes have been studied using the expanded beam x-ray facility at the Daresbury synchrotron. From on- axis measurements the encircled power distribution and the point spread function at three energies 6.627 keV, 8.837 ke...

  15. 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.

  16. 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.

  17. 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.)

  18. 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.

  19. Anisotropy of chemical bonding in semifluorinated graphite C2F revealed with angle-resolved X-ray absorption spectroscopy.

    Science.gov (United States)

    Okotrub, Alexander V; Yudanov, Nikolay F; Asanov, Igor P; Vyalikh, Denis V; Bulusheva, Lyubov G

    2013-01-22

    Highly oriented pyrolytic graphite characterized by a low misorientation of crystallites is fluorinated using a gaseous mixture of BrF(3) with Br(2) at room temperature. The golden-colored product, easily delaminating into micrometer-size transparent flakes, is an intercalation compound where Br(2) molecules are hosted between fluorinated graphene layers of approximate C(2)F composition. To unravel the chemical bonding in semifluorinated graphite, we apply angle-resolved near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and quantum-chemical modeling. The strong angular dependence of the CK and FK edge NEXAFS spectra on the incident radiation indicates that room-temperature-produced graphite fluoride is a highly anisotropic material, where half of the carbon atoms are covalently bonded with fluorine, while the rest of the carbon atoms preserve π electrons. Comparison of the experimental CK edge spectrum with theoretical spectra plotted for C(2)F models reveals that fluorine atoms are more likely to form chains. This conclusion agrees with the atomic force microscopy observation of a chain-like pattern on the surface of graphite fluoride layers. PMID:23214423

  20. 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

  1. 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

  2. X-ray spectral studies of TeV gamma-ray emitting blazars

    CERN Document Server

    Wierzcholska, Alicja

    2016-01-01

    This work is a summary of the X-ray spectral studies of 29 TeV $\\gamma$-ray emitting blazars observed with Swift/XRT, especially focusing on sources for which X-ray regime allows to study the low and the high energy ends of the particle distributions function. Variability studies require simultaneous coverage, ideally sampling different flux states of each source. This is achieved using X-ray observations by disentangling the high-energy end of the synchrotron emission and the low-energy end of the Compton emission, which are produced by the same electron population. We focused on a sample of 29 TeV gamma-ray emitting blazars with the best signal-to-noise X-ray observations collected with Swift/XRT in the energy range of 0.3-10 keV during 10 years of Swift/XRT operations. We investigate the X-ray spectral shapes and the effects of different corrections for neutral hydrogen absorption and decompose the synchrotron and inverse Compton components. In the case of 5 sources (3C 66A, S5 0716+714, W Comae, 4C +21.35...

  3. Advanced X-Ray scattering methods for the study of structure and its evolution in soft materials with fiber symmetry

    International Nuclear Information System (INIS)

    Three recently developed evaluation methods for the automated quantitative analysis of X-ray scattering data (small-angle (SAXS) and wide-angle (WAXS)) are presented. They are applicable to extensive series of 2D patterns that are recorded in studies of polymer materials with uniaxial symmetry. The experiments comprise time-resolved studies (melting, crystallization, mechanical properties and fatigue) as well as microbeam-scanning for the study of nanostructure gradients. The methods appear suitable to manage the data flood from modern synchrotron radiation setups aiming at the extraction of quantitative information on the structure evolution inside the material. In microbeam-scanning experiments the recorded scattering patterns are smeared. It is proposed to reconstruct desmeared scattering patterns by an X-ray scattering fiber-computer-tomography (XS-FCT). Reconstruction aberrations yield additional structure information. The true structure variation along the fiber radius is established. Compared to general tomography the experiment is faster by a factor of 100, and reconstruction is faster by a factor of 104. In WAXS fiber patterns should first be mapped into reciprocal space before analysis. After having corrected an erroneous tilt-angle equation, automatic tilt-angle tracking and mapping becomes possible. If polymers fail at low strain, the determination of strain and of structural parameters from the scattering patterns require very high accuracy because the observed variations are subtle. Suitable methods are presented both for the high-precision determination of the macroscopic strain, and for the determination of subtle variations of structure parameters.

  4. 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)

  5. 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)

  6. 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.

  7. 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.

  8. Ultrashort X-ray pulse science

    International Nuclear Information System (INIS)

    A variety of phenomena involves atomic motion on the femtosecond time-scale. These phenomena have been studied using ultrashort optical pulses, which indirectly probe atomic positions through changes in optical properties. Because x-rays can more directly probe atomic positions, ultrashort x-ray pulses are better suited for the study of ultrafast structural dynamics. One approach towards generating ultrashort x-ray pulses is by 90o Thomson scattering between terawatt laser pulses and relativistic electrons. Using this technique, the author generated ∼ 300 fs, 30 keV (0.4 (angstrom)) x-ray pulses. These x-ray pulses are absolutely synchronized with ultrashort laser pulses, allowing femtosecond optical pump/x-ray probe experiments to be performed. Using the right-angle Thomson scattering x-ray source, the author performed time-resolved x-ray diffraction studies of laser-perturbated InSb. These experiments revealed a delayed onset of lattice expansion. This delay is due to the energy relaxation from a dense electron-hole plasma to the lattice. The dense electron-hole plasma first undergoes Auger recombination, which reduces the carrier concentration while maintaining energy content. Longitudinal-optic (LO) phonon emission then couples energy to the lattice. LO phonon decay into acoustic phonons, and acoustic phonon propagation then causes the growth of a thermally expanded layer. Source characterization is instrumental in utilizing ultrashort x-ray pulses in time-resolved x-ray spectroscopies. By measurement of the electron beam diameter at the generation point, the pulse duration of the Thomson scattered x-rays is determined. Analysis of the Thomson scattered x-ray beam properties also provides a novel means of electron bunch characterization. Although the pulse duration is inferred for the Thomson scattering x-ray source, direct measurement is required for other x-ray pulse sources. A method based on the laser-assisted photoelectric effect (LAPE) has been

  9. Ultrashort X-ray pulse science

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Alan Hap [Univ. of California, Berkeley, CA (US). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    1998-05-01

    A variety of phenomena involves atomic motion on the femtosecond time-scale. These phenomena have been studied using ultrashort optical pulses, which indirectly probe atomic positions through changes in optical properties. Because x-rays can more directly probe atomic positions, ultrashort x-ray pulses are better suited for the study of ultrafast structural dynamics. One approach towards generating ultrashort x-ray pulses is by 90{sup o} Thomson scattering between terawatt laser pulses and relativistic electrons. Using this technique, the author generated {approx} 300 fs, 30 keV (0.4 {angstrom}) x-ray pulses. These x-ray pulses are absolutely synchronized with ultrashort laser pulses, allowing femtosecond optical pump/x-ray probe experiments to be performed. Using the right-angle Thomson scattering x-ray source, the author performed time-resolved x-ray diffraction studies of laser-perturbated InSb. These experiments revealed a delayed onset of lattice expansion. This delay is due to the energy relaxation from a dense electron-hole plasma to the lattice. The dense electron-hole plasma first undergoes Auger recombination, which reduces the carrier concentration while maintaining energy content. Longitudinal-optic (LO) phonon emission then couples energy to the lattice. LO phonon decay into acoustic phonons, and acoustic phonon propagation then causes the growth of a thermally expanded layer. Source characterization is instrumental in utilizing ultrashort x-ray pulses in time-resolved x-ray spectroscopies. By measurement of the electron beam diameter at the generation point, the pulse duration of the Thomson scattered x-rays is determined. Analysis of the Thomson scattered x-ray beam properties also provides a novel means of electron bunch characterization. Although the pulse duration is inferred for the Thomson scattering x-ray source, direct measurement is required for other x-ray pulse sources. A method based on the laser-assisted photoelectric effect (LAPE) has

  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. 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.

  12. Monolayer sorption of neon in mesoporous silica glass as monitored by wide-angle x-ray scattering.

    Science.gov (United States)

    Kilburn, Duncan; Sokol, Paul E

    2008-02-01

    We report measurements of the x-ray scattering intensity as mesoporous silica glasses are filled with neon. The intensity of the first peak in the liquidlike diffraction pattern increases nonlinearly with mass adsorbed. We outline a simple model assuming that the major coherent contribution to the first peak in the scattering function S(Q) is due to interference from nearest-neighbor scatterers. This allows us to demonstrate an approach for surface area determination which does not rely on thermodynamic models -- and is therefore complementary to existing methods. We also suggest that the overestimation of surface area by the traditional Brunauer-Emmett-Teller method may be resolved by using the capillary, and not the bulk, condensation pressure as the reference pressure p(0). Furthermore, the alternative analysis offers an insight into the atomic structure of monatomic sorption, which may be of use for further studies on materials with different surface properties.

  13. 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

  14. 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.

  15. Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies

    International Nuclear Information System (INIS)

    Electron paramagnetic resonance (EPR) and online UV–visible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage, to confirm a multi-track radiation-damage process and to develop a model of that process. Electron paramagnetic resonance (EPR) and online UV–visible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage. Online UV–visible spectroscopy showed that upon X-irradiation, disulfide radicalization appeared to saturate at an absorbed dose of approximately 0.5–0.8 MGy, in contrast to the saturating dose of ∼0.2 MGy observed using EPR at much lower dose rates. The observations suggest that a multi-track model involving product formation owing to the interaction of two separate tracks is a valid model for radiation damage in protein crystals. The saturation levels are remarkably consistent given the widely different experimental parameters and the range of total absorbed doses studied. The results indicate that even at the lowest doses used for structural investigations disulfide bonds are already radicalized. Multi-track considerations offer the first step in a comprehensive model of radiation damage that could potentially lead to a combined computational and experimental approach to identifying when damage is likely to be present, to quantitate it and to provide the ability to recover the native unperturbed structure

  16. Preliminary experiment of fluorescent X-ray computed tomography to detect dual agents for biological study.

    Science.gov (United States)

    Yu, Q; Takeda, T; Yuasa, T; Hasegawa, Y; Wu, J; Thet-Thet-Lwin; Hyodo, K; Dilmanian, F A; Itai, Y; Akatsuka, T

    2001-05-01

    The simultaneous observation of various information, such as blood flow, tissue metabolism and distribution of receptors, is quite important in order to understand the functional state of biomedical objects. The simultaneous detectability of contrast agents by fluorescent X-ray computed tomography (FXCT) with synchrotron radiation is examined in this study. The system consisted of a silicon (111) double-crystal monochromator, an X-ray slit system, a scanning table, a PIN diode, a highly purified germanium detector and an X-ray charge-coupled device (CCD) camera. The monochromatic X-ray beam energy was adjusted to 37.0 keV and collimated into a pencil beam of 1 x 1 mm. The fluorescent spectra of the K alpha lines for iodine and xenon were detected simultaneously. FXCT could image the distribution of both iodine and xenon agents in a phantom clearly and the contrast ratio was significantly better than that of transmission X-ray computed tomography images. PMID:11486409

  17. Study of Post-Harvest Ambon Banana (Musa acuminata) Preservation Using X-Ray

    Science.gov (United States)

    Dwijananti, P.; Handayani, L.; Marwoto, P.; Iswari, R. S.

    2016-08-01

    An exposure to Ambon banana (Musa Acuminata) samples has been done by using X-rays with current, voltage and exposure time are control parameters. This study aimed to determine storage ability of the post-harvest sample. Five samples were exposured by x-rays with the dose of (3-5) × 10-14 Gy. The samples were stored at room temperature. Their mass and physical condition (color and smell) were evaluated every 3 days. It was found that the control sample which was not exposured by X-ray was ripe in the sixth day indicated by the yellow color and good smell of the banana. Meanwhile, the samples which were exposured by (3 - 5) × 10-14 Gy doze of X-ray looked fresher and still had green color. These samples showed their ripening in the ninth day and their mass decrease was (12-13)% which is lower than the control sample. The preservation of banana can be done through low-dose X-ray exposure.

  18. Comprehensive study of the X-ray flares from gamma-ray bursts observed by Swift

    CERN Document Server

    Yi, Shuang-Xi; Yu, Hai; Wang, F Y; Mu, Hui-Jun; Lv, Lian-Zhong; Liang, En-Wei

    2016-01-01

    X-ray flares are generally supposed to be produced by the later central engine activities, and may share the similar physical origin with prompt emission of gamma-ray bursts (GRBs). In this paper, we have analyzed all significant X-ray flares from the GRBs observed by {\\em Swift} from April 2005 to March 2015. The catalog contains 468 bright X-ray flares, including 200 flares with redshifts. We obtain the fitting results of X-ray flares, such as start time, peak time, duration, peak flux, fluence, peak luminosity, and mean luminosity. The peak luminosity decreases with peak time, following a power-law behavior $L_p \\propto T_{peak,z}^{-1.27}$. The flare duration increases with peak time. The 0.3-10 keV isotropic energy of X-ray flares distribution is a lognormal peaked at $10^{51.2}$ erg. We also study the frequency distributions of flare parameters, including energies, durations, peak fluxes, rise times, decay times and waiting times. Power-law distributions of energies, durations, peak fluxes, and waiting t...

  19. X-ray fluorescence applied to the fission time study of Z=120 element

    International Nuclear Information System (INIS)

    Characteristic X-rays of the element Z=120 have been identified in the reaction 238U+64Ni at 6,6 MeV per nucleon. They have been detected in coincidence with fission fragments arising from composite systems with 120 protons formed during the reaction. Pieces of information about the formation probability by fusion of Z=120 nuclei and on the fission time of this nucleus have been inferred from the X-ray multiplicity. From the maximal measured X-ray multiplicity and with the assumption of an exponential distribution of fission times, we have determined an inferior limit of 4.0*10-18 s for the mean fission time of Z=120 nuclei. This maximal measured X-ray has also allowed us to state that at best 38% of capture reactions (it means quasi-fission + fusion reactions) correspond to quasi-fission reactions associated with times below than 10-19 seconds. This relatively low percentage of quasi-fission reactions is not consistent with the very low fusion probabilities generally expected for our system. This work has shown that the X-ray fluorescence technique can be used successfully for studying the stability of super-heavy elements

  20. Monte Carlo study of characteristics of uranium L-edge from X-ray absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seunghoon; Kwak, Sung-Woo; Shin, Jung-Ki; Kang, Han-Byeol; Chung, Heejun [Korea Institute of Nuclear Nonproliferation and Control, Daejeon (Korea, Republic of)

    2015-05-15

    L-edge densitometry (LED) which is specially called X-ray Absorption Spectrometry (XAS) for uranium xray analysis is a technique of determination of uranium concentration as a continuous x-ray energy beams transmit a uranium liquid sample for safeguard. Compared to K-edge densitometer, since relatively lower energy of uranium L series energy than K series energy, L-edge densitometer does not require a liquid nitride cooling system. In this study, the simulation of uranium L-edge densitometer is performed using Monte Carlo method. Ledge spectrum, such as spectrum jumps, can be confirmed by the simulation. In further study, improvement of counting efficiency through collimation of x-ray, and shielding will be considered for detailed design of L-edge densitometer.

  1. Polychromatic X-ray micro- and nanodiffraction for spatially-resolved structural studies

    International Nuclear Information System (INIS)

    The availability of intense, focused synchrotron X-ray microbeams has enabled new techniques for materials investigations with sub-micron spatial resolution. The scanning microbeam setup we have developed at the XOR-UNI beamline at the Advanced Photon Source (APS) is versatile in that it provides 1D, 2D or 3D scans (including depth resolution), and can alternate between polychromatic- and monochromatic-beam modes. Focusing in both modes uses elliptical Kirkpatrick-Baez (K-B) reflecting mirrors. Beam diameters of ∼ 500 nm FWHM are now routine, and 90 nm focus has been demonstrated. In white-beam mode, a CCD detector records a complete Laue diffraction pattern, which is analyzed with an automated indexing program. These X-ray diffraction patterns provide real-space maps of the local lattice structure, crystal orientation, grain morphology, and strain tensor. Spatially-resolved X-ray microdiffraction studies are now providing previously unavailable measurements of local microstructures. These measurements, in turn, yield new insights in several classic fields of materials science. This paper will illustrate the application of polychromatic scanning X-ray microscopy with examples from 1D, 2D and 3D materials systems. In 1D systems, we have mapped the structure and orientation of an individual ZnO nanorod along with the associated Ge catalyst particle used to control the nanocrystal growth. In 2D systems, X-ray microdiffraction studies have revealed the mechanisms for local crystallographic tilting in epitaxial oxide films grown on textured Ni substrates for superconducting applications. In 3D systems, X-ray microscopy investigations have included in-situ studies of microstructural evolution during thermal grain growth in polycrystalline aluminum. In general, these spatially-resolved measurements provide important new insights and are valuable as input for theoretical and computer modeling studies of a wide range of material processes

  2. Channeling and parametric X-ray studies at the SAGA Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Takabayashi, Y., E-mail: takabayashi@saga-ls.jp [SAGA Light Source, 8-7 Yayoigaoka, Tosu, Saga 841-0005 (Japan); Korotchenko, K.B.; Pivovarov, Yu.L.; Tukhfatullin, T.A. [National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation)

    2013-11-15

    We present experimental results on channeling and parametric X-ray radiation obtained using a 255-MeV electron beam from an injector linac at the SAGA Light Source. Using a screen monitor, we observed both channeling phenomena and doughnut scattering by measuring the profile of an electron beam transmitted through a 20-μm-thick Si crystal. We also measured the angular distribution of parametric X-ray radiation using an imaging plate as a two-dimensional X-ray detector. The obtained results are in good agreement with theory. The final goal of these studies is the first observation of diffracted channeling radiation, and our strategy for achieving this is discussed.

  3. The Study on the Attenuation of X-ray and Imaging Quality by Contents in Stomach

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Kyung Rae; Ji, Youn Sang; Kim, Chang Bok; Choi, Seong Kwan; Moon, Sang In [Dept. of Radiological Technology, Gwangju Health College University, Gwangju (Korea, Republic of); Dieter, Kevin [Dept. of Physical Therapy, Gwangju Health College University, Gwangju (Korea, Republic of)

    2009-03-15

    This study examined the change in the attenuation of X-rays with the ROI (Region of Interest) in DR (Digital Radiography) according to the stomach contents by manufacturing a tissue equivalent material phantom to simulate real stomach tissue based on the assumption that there is some attenuation of X-rays and a difference in imaging quality according to the stomach contents. The transit dosage by the attenuation of X-rays decreased with increasing protein thickness, which altered the average ROI values in the film and DR images. A comparison of the change in average ROI values of the film and DR image showed that the image in film caused larger density changes with varying thickness of protein than the image by DR. The results indicate that NPO (nothing by mouth) is more important in film system than in DR system.

  4. Cr/B4C multilayer mirrors: Study of interfaces and X-ray reflectance

    Science.gov (United States)

    Burcklen, C.; Soufli, R.; Dennetiere, D.; Polack, F.; Capitanio, B.; Gullikson, E.; Meltchakov, E.; Thomasset, M.; Jérome, A.; de Rossi, S.; Delmotte, F.

    2016-03-01

    We present an experimental study of the effect of layer interfaces on the x-ray reflectance in Cr/B4C multilayer interference coatings with layer thicknesses ranging from 0.7 nm to 5.4 nm. The multilayers were deposited by magnetron sputtering and by ion beam sputtering. Grazing incidence x-ray reflectometry, soft x-ray reflectometry, and transmission electron microscopy reveal asymmetric multilayer structures with a larger B4C-on-Cr interface, which we modeled with a 1-1.5 nm thick interfacial layer. Reflectance measurements in the vicinity of the Cr L2,3 absorption edge demonstrate fine structure that is not predicted by simulations using the currently tabulated refractive index (optical constants) values for Cr.

  5. Study of Scintillator thickness optimization of lens-coupled X-ray imaging detectors

    Science.gov (United States)

    Xie, H.; Du, G.; Deng, B.; Chen, R.; Xiao, T.

    2016-03-01

    Lens-coupled X-ray in-direct imaging detectors are very popular for high-resolution X-ray imaging at the third generation synchrotron radiation facilities. This imaging system consists of a scintilator producing a visible-light image of X-ray beam, a microscope objective, a mirror reflecting at 90° and a CCD camera. When the thickness of the scintillator is matched with the numerical aperture (NA) of the microscope objective, the image quality of experimental results will be improved obviously. This paper used an imaging system at BL13W beamline of Shanghai Synchrotron Radiation Facility (SSRF) to study the matching relation between the scintillator thickness and the NA of the microscope objective with a real sample. By use of the matching relation between the scintillator thickness and the NA of the microscope objective, the optimal imaging results have been obtained.

  6. Study of X-ray Kirkpatrick-Baez imaging with single layer

    Institute of Scientific and Technical Information of China (English)

    Baozhong Mu; Zhanshan Wang; Shengzhen Yi; Xin Wang; Shengling Huang; Jingtao Zhu; Chengchao Huang

    2009-01-01

    The X-ray Kirkpatrick-Baez(KB)imaging experiment with single layer is implemented.Based on the astigmatism aberration and residual geometric aberration of a single mirror.a KB system with 16x mean magnification and approxinlately 0.45° grazing incidence angle is designed.The mirrors are deposited with an Ir layer of 20-nm thickness.Au grids backlit by X-ray tube of 8 keV are imaged via the KB system on scintillator charge-coupled device(CCD).In the ±80 μm field,resolutions of less than 5 μm are measured.The result is in good agreenmnt with the simulated imaging.

  7. 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)

  8. A Systematic Chandra study of Sgr A$^{\\star}$: I. X-ray flare detection

    OpenAIRE

    Yuan, Qiang; Wang, Q. Daniel

    2015-01-01

    Daily X-ray flaring represents an enigmatic phenomenon of Sgr A$^{\\star}$ --- the supermassive black hole at the center of our Galaxy. We report initial results from a systematic X-ray study of this phenomenon, based on extensive {\\it Chandra} observations obtained from 1999 to 2012, totaling about 4.5 Ms. We detect flares, using a combination of the maximum likelihood and Markov Chain Monte Carlo methods, which allow for a direct accounting for the pile-up effect in the modeling of the flare...

  9. Optical and x-ray time resolved study of the structural transition in mixed valence manganites

    Directory of Open Access Journals (Sweden)

    Jia Q. X.

    2013-03-01

    Full Text Available Time resolved optical reflectivity and x-ray diffraction techniques are employed to study the laser-induced structural response in two charge and orbitally ordered manganites. Optical data indicate a non-thermal nature of the laser-triggered phase transition via the disappearance of an optical phonon related to the charge and orbitally ordered phase. The x-ray diffraction measurements on superlattice reflections confirm the non-thermal time scale of the initial step of this phase transition but also show that the complete change of structural symmetry is not instantaneous.

  10. Positional order in Langmuir monolayers: An X-ray diffraction study

    DEFF Research Database (Denmark)

    Kaganer, V.M.; Brezesinski, G.; Möhwald, H.;

    1999-01-01

    The structural phase transition from the hexagonal to a distorted-hexagonal (centered rectangular) phase (the LS-S transition) in Langmuir monolayers of octadecanol is studied in a grazing incidence x-ray diffraction experiment. We find algebraic decay of positional correlations, which suggests...... solid-like order in both phases at the distances accessible in the present x-ray diffraction experiment. The transition is accompanied by strong positional disorder, which is evident from the drastic increase of the exponent eta to values eta>2 close to the transition. Remarkably, on approaching...

  11. Crystallization and preliminary X-ray diffraction study of porcine carboxypeptidase B

    Energy Technology Data Exchange (ETDEWEB)

    Akparov, V. Kh., E-mail: valery@akparov.ru [Scientific Center of Russian Federation Research Institute for Genetics and Selection of Industrial Microorganisms (Russian Federation); Timofeev, V. I., E-mail: inna@ns.crys.ras.ru; Kuranova, I. P., E-mail: tostars@mail.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2015-05-15

    Crystals of porcine pancreatic carboxypeptidase B have been grown in microgravity by the capillary counter-diffusion method through a gel layer. The X-ray diffraction study showed that the crystals belong to sp. gr. P4{sub 1}2{sub 1}2 and have the following unit-cell parameters: a = b = 79.58 Å, c = 100.51 Å; α = β = γ = 90.00°. The X-ray diffraction data set suitable for the determination of the three-dimensional structure at atomic resolution was collected from one of the grown crystals at the SPring 8 synchrotron facility to 0.98 Å resolution.

  12. Femtosecond laser driven XUV sources: high-harmonic and OFI X-ray laser studies

    Energy Technology Data Exchange (ETDEWEB)

    Balcou, Ph.; Sebban, S.; Haroutunian, R.; Grillon, G.; Rousseau, J.P.; Rousse, A.; Notebaert, L.; Pittman, M.; Chambaret, J.P.; Hulin, D. [Propagation des Ondes en Milieux Aleatoires et/ou Non-Lineares (POAN), 91 - Palaiseau (France). Groupement de Recherches; Klisnick, A.; Ros, D.; Jaegle, P.; Carillon, A.; Jamelot, G. [Propagation des Ondes en Milieux Aleatoires et/ou Non-Lineares (POAN), 91 - Palaiseau (France). Groupement de Recherches; Lab. de Spectroscopie Atomique et Ionique, Univ. Paris-Sud, Orsay (France); Wyart, J.F. [Propagation des Ondes en Milieux Aleatoires et/ou Non-Lineares (POAN), 91 - Palaiseau (France). Groupement de Recherches; Lab. Aime Cotton, Univ. Paris-Sud, Orsay (France)

    2001-07-01

    We report recent experimental results obtained at LOA on a femtosecond driven collisional X-ray laser. The experiment has consisted in studying the amplification of the 4d{sup 9}5p-4d{sup 9}5d line at 41.8 nm in Pd-like xenon. This lasing emission has been observed to dominate the output spectra when focusing a 20 TW 10 Hz Ti: sapphire laser system in a few mm gas cell. The influence of several parameters on the X-ray laser emission is presented. A comparison with high harmonic sources is drawn. (orig.)

  13. Study of x-ray emission enhancement via high contrast femtosecond laser interacting with solid foil

    International Nuclear Information System (INIS)

    We studied the hard x-ray emission and the Kα x-ray conversion efficiency (ηK) produced by 60 fs high contrast frequency doubled Ti: sapphire laser pulse focused on Cu foil target. Cu Kα photon emission obtained with second harmonic laser pulse is more intense than the case of fundamental laser pulse. The Cu ηK shows strong dependence on laser nonlinearly skewed pulse shape and reaches the maximum value 4x10-4 with 100 fs negatively skewed pulse. It shows the electron spectrum shaping contribute to the increase of ηK. (author)

  14. A Chandra X-ray Study of Cygnus A - III. The Cluster of Galaxies

    OpenAIRE

    Smith, David A.; Wilson, Andrew S.; Arnaud, Keith A.; Terashima, Yuichi; Young, Andrew J.

    2001-01-01

    The results from a recent Chandra ACIS-S study of the cluster surrounding Cygnus A are presented. We have deprojected the X-ray spectra taken from various elliptical shells in order to derive the run of temperature, density, pressure, and abundance for the ICM as a function of radius. We confirm a drop in temperature of the X-ray emitting gas from $\\sim 8$ keV more than $\\sim 2^{\\prime}$ from the center to $\\simeq 5$ keV some $30^{\\prime\\prime}$ from the center, with the coolest gas immediate...

  15. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    Science.gov (United States)

    Bertram, F.; Zhang, F.; Evertsson, J.; Carlà, F.; Pan, J.; Messing, M. E.; Mikkelsen, A.; Nilsson, J.-O.; Lundgren, E.

    2014-07-01

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  16. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bertram, F., E-mail: florian.bertram@sljus.lu.se; Evertsson, J.; Messing, M. E.; Mikkelsen, A.; Lundgren, E. [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Zhang, F.; Pan, J. [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas väg 51, 10044 Stockholm (Sweden); Carlà, F. [ESRF, B. P. 220, 38043 Grenoble (France); Nilsson, J.-O. [Sapa Technology, Kanalgatan 1, 612 31 Finspång (Sweden)

    2014-07-21

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  17. X-Ray Solution Scattering Study of Four Escherichia coli Enzymes Involved in Stationary-Phase Metabolism.

    Directory of Open Access Journals (Sweden)

    Liubov A Dadinova

    Full Text Available The structural analyses of four metabolic enzymes that maintain and regulate the stationary growth phase of Escherichia coli have been performed primarily drawing on the results obtained from solution small angle X-ray scattering (SAXS and other structural techniques. The proteins are (i class I fructose-1,6-bisphosphate aldolase (FbaB; (ii inorganic pyrophosphatase (PPase; (iii 5-keto-4-deoxyuronate isomerase (KduI; and (iv glutamate decarboxylase (GadA. The enzyme FbaB, that until now had an unknown structure, is predicted to fold into a TIM-barrel motif that form globular protomers which SAXS experiments show associate into decameric assemblies. In agreement with previously reported crystal structures, PPase forms hexamers in solution that are similar to the previously reported X-ray crystal structure. Both KduI and GadA that are responsible for carbohydrate (pectin metabolism and acid stress responses, respectively, form polydisperse mixtures consisting of different oligomeric states. Overall the SAXS experiments yield additional insights into shape and organization of these metabolic enzymes and further demonstrate the utility of hybrid methods, i.e., solution SAXS combined with X-ray crystallography, bioinformatics and predictive 3D-structural modeling, as tools to enrich structural studies. The results highlight the structural complexity that the protein components of metabolic networks may adopt which cannot be fully captured using individual structural biology techniques.

  18. Study on the effects of gadolinium-based MRI contrast medium on X-ray scanning

    International Nuclear Information System (INIS)

    Gadolinium has a higher atomic mass (64) than iodine (53). The K-edge absorption energy of gadolinium is 50.2 keV, which is in the absorbed wavelength range of the X-rays used by a CT scanner, suggesting that it has a high X-ray absorption ability. This study examined the effects of a gadolinium-based MRI contrast medium on the quality (mAs) and the quality (kVp) of radiation during a X-ray scan. A contrast medium phantom was manufactured after diluting the contrast medium to various concentrations. A CT scanner (Siemens, Somatom Senation 64, Germany) was used to obtain images by changing the quality of radiation from 80 kVp to 100, 120, and 140 kVp. At a constant quality of radiation of 120 kVp, the mAs was changed from 100 mAs to 200 and 300 mAs and images were obtained under each condition. The Hounsfield units (HUs) in a test tube were measured for analysis and comparison. The contrast enhancement by the contrast medium for CT scanning was 100% at a tube voltage of 80 kVp. The contrast enhancements at 100 kVp, 120 kVp, and 140 kVp were 93.8%, 87.7%, and 69.5%, respectively. In addition, although the quantity increased a fixed tube voltage, the HU of the test tube remained relatively constant, indicating that the absorption of the contrast medium had little association with the quantity of X-rays but had some correlation with the quality of radiation. A tube voltage of 80 kVp or lower is recommended when a MRI contrast medium is used CT scanning. When MRI scanning and X-ray scanning are conducted together, X-ray scanning should be performed first or after sufficient gadolinium contrast medium has been excreted.

  19. Angle resolved x-ray photoelectron spectroscopy (ARXPS) analysis of lanthanum oxide for micro-flexography printing

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, S., E-mail: suhaimihas@uthm.edu.my; Yusof, M. S., E-mail: mdsalleh@uthm.edu.my; Maksud, M. I., E-mail: midris1973@gmail.com [Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Johor (Malaysia); Embong, Z., E-mail: zaidi@uthm.edu.my [Faculty of Science, Technology and Human Development, Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Johor (Malaysia)

    2016-01-22

    Micro-flexography printing was developed in patterning technique from micron to nano scale range to be used for graphic, electronic and bio-medical device on variable substrates. In this work, lanthanum oxide (La{sub 2}O{sub 3}) has been used as a rare earth metal candidate as depositing agent. This metal deposit was embedded on Carbon (C) and Silica (Si) wafer substrate using Magnetron Sputtering technique. The choose of Lanthanum as a target is due to its wide application in producing electronic devices such as thin film battery and printed circuit board. The La{sub 2}O{sub 3} deposited on the surface of Si wafer substrate was then analyzed using Angle Resolve X-Ray Photoelectron Spectroscopy (ARXPS). The position for each synthetic component in the narrow scan of Lanthanum (La) 3d and O 1s are referred to the electron binding energy (eV). The La 3d narrow scan revealed that the oxide species of this particular metal is mainly contributed by La{sub 2}O{sub 3} and La(OH){sub 3}. The information of oxygen species, O{sup 2-} component from O 1s narrow scan indicated that there are four types of species which are contributed from the bulk (O{sup 2−}), two chemisorb component (La{sub 2}O{sub 3}) and La(OH){sub 3} and physisorp component (OH). Here, it is proposed that from the adhesive and surface chemical properties of La, it is suitable as an alternative medium for micro-flexography printing technique in printing multiple fine solid lines at nano scale. Hence, this paper will describe the capability of this particular metal as rare earth metal for use in of micro-flexography printing practice. The review of other parameters contributing to print fine lines will also be described later.

  20. 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.

  1. Angle resolved x-ray photoelectron spectroscopy (ARXPS) analysis of lanthanum oxide for micro-flexography printing

    Science.gov (United States)

    Hassan, S.; Yusof, M. S.; Embong, Z.; Maksud, M. I.

    2016-01-01

    Micro-flexography printing was developed in patterning technique from micron to nano scale range to be used for graphic, electronic and bio-medical device on variable substrates. In this work, lanthanum oxide (La2O3) has been used as a rare earth metal candidate as depositing agent. This metal deposit was embedded on Carbon (C) and Silica (Si) wafer substrate using Magnetron Sputtering technique. The choose of Lanthanum as a target is due to its wide application in producing electronic devices such as thin film battery and printed circuit board. The La2O3 deposited on the surface of Si wafer substrate was then analyzed using Angle Resolve X-Ray Photoelectron Spectroscopy (ARXPS). The position for each synthetic component in the narrow scan of Lanthanum (La) 3d and O 1s are referred to the electron binding energy (eV). The La 3d narrow scan revealed that the oxide species of this particular metal is mainly contributed by La2O3 and La(OH)3. The information of oxygen species, O2- component from O 1s narrow scan indicated that there are four types of species which are contributed from the bulk (O2-), two chemisorb component (La2O3) and La(OH)3 and physisorp component (OH). Here, it is proposed that from the adhesive and surface chemical properties of La, it is suitable as an alternative medium for micro-flexography printing technique in printing multiple fine solid lines at nano scale. Hence, this paper will describe the capability of this particular metal as rare earth metal for use in of micro-flexography printing practice. The review of other parameters contributing to print fine lines will also be described later.

  2. Angle resolved x-ray photoelectron spectroscopy (ARXPS) analysis of lanthanum oxide for micro-flexography printing

    International Nuclear Information System (INIS)

    Micro-flexography printing was developed in patterning technique from micron to nano scale range to be used for graphic, electronic and bio-medical device on variable substrates. In this work, lanthanum oxide (La2O3) has been used as a rare earth metal candidate as depositing agent. This metal deposit was embedded on Carbon (C) and Silica (Si) wafer substrate using Magnetron Sputtering technique. The choose of Lanthanum as a target is due to its wide application in producing electronic devices such as thin film battery and printed circuit board. The La2O3 deposited on the surface of Si wafer substrate was then analyzed using Angle Resolve X-Ray Photoelectron Spectroscopy (ARXPS). The position for each synthetic component in the narrow scan of Lanthanum (La) 3d and O 1s are referred to the electron binding energy (eV). The La 3d narrow scan revealed that the oxide species of this particular metal is mainly contributed by La2O3 and La(OH)3. The information of oxygen species, O2- component from O 1s narrow scan indicated that there are four types of species which are contributed from the bulk (O2−), two chemisorb component (La2O3) and La(OH)3 and physisorp component (OH). Here, it is proposed that from the adhesive and surface chemical properties of La, it is suitable as an alternative medium for micro-flexography printing technique in printing multiple fine solid lines at nano scale. Hence, this paper will describe the capability of this particular metal as rare earth metal for use in of micro-flexography printing practice. The review of other parameters contributing to print fine lines will also be described later

  3. An X-Ray Study of Lobe-Dominated Radio-Loud Quasars with XMM-Newton

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We report on our results of X-ray spectral analysis for a sample of radio-loud quasars covering a wide range of the radio core-dominance parameter, R, from core-dominated to lobe-dominated objects, using data obtained mostly with the XMM-Newton Observatory. We find that the spectral shape of the underlying power-law continuum is flat even for the lobe-dominated objects (average photon index ~ 1.5), indistinguishable from that of core-dominated quasars. For lobe-dominated objects, contribution of X-rays from the jets is expected to be very small based on previous unification schemes, more than one order of magnitude lower than the observed X-ray luminosities. Assuming that radio-loud quasars follow the same X-ray-UV/optical luminosity relation for the disk-corona emission as found for radio-quiet quasars, we estimate the X-ray flux contributed by the disk-corona component from the optical/UV continuum. We find that neither the luminosity, nor the spectral shape, of the disk-corona X-ray emission can account for the bulk of the observed X-ray properties. Thus in lobe-dominated quasars, either the disk-corona X-ray emission is much enhanced in strength and flatter in spectral shape (photon index~1.5) compared to normal radio-quiet quasars, or their jet X-ray emission is much enhanced compared to their weak radio core-jet emission. If the latter is the case, our result may imply that the jet emission in X-rays is less Doppler beamed than that in the radio. As a demonstrating example, we test this hypothesis by using a specific model in which the X-ray jet has a larger opening angle than the radio jet.

  4. 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.

  5. X-ray diffraction study into the effects of liming on the structure of collagen.

    Science.gov (United States)

    Maxwell, Clark A; Wess, Tim J; Kennedy, Craig J

    2006-08-01

    The manufacture of parchment from animal skin involves processes that remove hair, fats, and other macromolecules. Although it is well understood that the collagen fibers "open up" during processing, this study uses small and wide-angle X-ray diffraction to measure quantitatively the changes induced at the nanoscopic and microscopic levels. The axial rise per residue distance within the collagen molecules is unaffected by salt and lime treatments. Salting of the hides appears to remove noncollagenous materials. The intermolecular lateral packing distance between the hydrated collagen molecules (1.4 nm) increases after salting ( approximately 1.5 nm) and liming ( approximately 1.55 nm); drying is responsible for a reduction to approximately 1.2 nm in all samples. The axial staggered array (d spacing) is reduced by 1 nm after liming and is unaffected by drying. The average fibril diameter increases from 103.2 to 114.5 nm following liming, and the fibril-to-fibril distance increases from 122.6 to 136.1 nm. PMID:16903677

  6. X-ray scattering studies on multiphasic polymer systems

    OpenAIRE

    Denchev, Z.; Viana, J. C.

    2011-01-01

    The scope of the present chapter had to be limited to some recent studies on the application of synchrotron WAXS and SAXS in three particular multicomponent and multiphase polymer systems. The first system comprises materials that became known as microfibrillar reinforced composites (MFC) produced from oriented blends of thermoplastic semicrystalline polymers by conventional processing techniques. These materials belong to fiber-reinforced composites that have many important engineering appli...

  7. Multiwavelength Studies of X-ray Selected AGN

    Science.gov (United States)

    Paronyan, G. M.; Mickaelian, A. M.; Abrahamyan, H. V.

    2016-06-01

    We present multiwavelength studies of the AGN and galaxy samples of the HRC/BHRC Joint Catalogue, optical identifications of ROSAT BSC and FSC sources. The extragalactic sample contains 4253 candidate AGN and 492 galaxies without a sign of activity. Multiwavelength data were retrieved from γ-ray to radio providing 62 photometric points in the range 100 GeV - 151 MHz. Color-color diagrams were built to investigate the nature of these objects. Activity types were taken from the SDSS DR12 spectroscopic database, as well as NED and HyperLEDA. So far, 451 objects remain as AGN candidates to be confirmed by spectroscopic observations.

  8. Phases of phosphatidyl ethanolamine monolayers studied by synchrotron x-ray scattering

    DEFF Research Database (Denmark)

    Helm, C.A.; Tippmann-Krayer, P.; Möhwald, H.;

    1991-01-01

    For the first time, phospholid monolayers at the air/water interface have been studied by x-ray diffraction and reflection all along the isotherm from the laterally isotropic fluid (the so-called LE phase) to the ordered phases. The model used to analyze the data, and the accuracy of the paramete...

  9. X-ray photoemission spectroscopy study on the effects of functionalization in fulleropyrrolidine and pyrrolidine derivatives

    NARCIS (Netherlands)

    Benne, Darja; Maccallini, Enrico; Rudolf, Petra; Sooambar, Chloe; Prato, Maurizio

    2006-01-01

    Fulleropyrrolidine and pyrrolidine derivatives were studied using X-ray photoemission spectroscopy in order to determine the effects of the C(60)-cage on the pyrrolidine nitrogen, as well as the influence of further derivatisation. Charge transfer from the carbon pyrrolidine ring to the C(60)-cages

  10. X-ray photoelectron spectroscopy for the study of microbial cell surfaces

    NARCIS (Netherlands)

    van der Mei, Henderina C; de Vries, Jacob; Busscher, Hendrik J

    2000-01-01

    X-ray photoelectron spectroscopy (XPS) is well known for the characterisation of material surfaces, but at first glance, is an unexpected technique to study the composition of microbial cell surfaces. Despite the fact that intimate contact between materials and microbial cell surfaces occurs in many

  11. High Pressure X-ray Absorption Studies on Correlated-Electron Systems

    Energy Technology Data Exchange (ETDEWEB)

    Cornelius, Andrew L. [Univ. of Nevada, Las Vegas, NV (United States)

    2016-08-26

    This project used high pressure to alter the electron-electron and electron-lattice interactions in rare earth and actinide compounds. Knowledge of these properties is the starting points for a first-principles understanding of electronic and electronically related macroscopic properties. The research focused on a systematic study of x-ray absorption measurements on rare earth and actinide compounds.

  12. Tensile behavior of orthorhombic alpha ''-titanium alloy studied by in situ X-ray diffraction

    DEFF Research Database (Denmark)

    Wang, X.D.; Lou, H.B.; Ståhl, Kenny;

    2010-01-01

    The tensile behavior of a Ti-11%Zr-14%Nb-10%Sn alloy with pure orthorhombic alpha '' phase was studied by in situ X-ray diffraction using synchrotron radiation. It is found that no phase transformation happens during the whole tensile process. The "double-yielding" platforms of this alloy...

  13. High-pressure phases of uranium monophosphide studied by synchrotron x-ray diffraction

    DEFF Research Database (Denmark)

    Olsen, J. Staun; Gerward, Leif; Benedict, U.;

    1988-01-01

    X-ray diffraction studies have been performed on UP powder for pressures up to 51 GPa using synchrotron radiation and a diamond-anvil cell. At ambient pressure UP has the rocksalt structure. The bulk modulus has been determined to B0=102(4) GPa and its pressure derivative to B0’=4.0(8). The cubic...

  14. Experimental study of hard X-rays emitted from meter-scale positive discharges in air

    NARCIS (Netherlands)

    Kochkin, P.O.; Nguyen, C.V.; Deursen, A. van; Ebert, U.

    2012-01-01

    We investigate structure and evolution of long positive spark breakdown; and we study at which stage pulses of hard x-rays are emitted. Positive high-voltage pulses of standardized lightning impulse wave form of about 1 MV were applied to about 1 m of ambient air. The discharge evolution was imaged

  15. Combination of Raman, infrared, and X-ray energy-dispersion spectroscopies and X-ray d diffraction to study a fossilization process

    Energy Technology Data Exchange (ETDEWEB)

    Sousa Filho, Francisco Eduardo de [Departamento de Fisica, Universidade Regional do Cariri, Crato, CE (Brazil); Joao Herminio da Silva [Universidade Federal do Ceara, Cariri, Juazeiro do Norte, CE (Brazil); Saraiva, Antonio Alamo Feitosa; Brito, Deyvid Dennys S. [Departamento de Ciencias Biologicas, Universidade Regional do Cariri, Crato, CE (Brazil); Viana, Bartolomeu Cruz [Departamento de Fisica, Universidade Federal do Piaui, Teresina, PI, (Brazil); Abagaro, Bruno Tavares de Oliveira; Freire, Paulo de Tarso Cavalcante, E-mail: tarso@fisica.ufc.br [Departamento de Fisica, Universidade Federal do Ceara, Fortaleza, CE (Brazil)

    2011-12-15

    X-ray diffraction was combined with X-ray energy-dispersion, Fourier-transform infrared, and Raman spectroscopies to study the fossilization of a Cretaceous specimen of the plant Brachyphyllum castilhoi, a fossil from the Ipubi Formation, in the Araripe Sedimentary Basin, Northeastern Brazil. Among the possible fossilization processes, which could involve pyrite, silicon oxide, calcium oxide, or other minerals, we were able to single out pyritization as the central mechanism producing the fossil, more than 100 million years ago. In addition to expanding the knowledge of the Ipubi Formation, this study shows that, when combined with other experimental techniques, Raman spectroscopy is a valuable tool at the paleontologist's disposal. (author)

  16. Studies on the ability of irradiated Escherichia coli bacteria to reactivate X-ray inactivated bacteriophages

    Energy Technology Data Exchange (ETDEWEB)

    Kiessling, W.

    1980-01-01

    The Weigle Reactivation phenomenon ie. the observation that low UV-flow irradiated bacteria increase the survival rate of UV-irradiated phages has not, to date, been studied with other forms of irradiation as inducers. In the studies reported here lambda-phages and E. coli cells in LB-medium were treated with X-rays. Host cells treated with an X-ray dose from 85 to 765 Gy showed a reactivation factor of 1.3 to 3.0 for X-ray inactivated phages. The capacity of the bacteria for phage reproduction did not appear to be markedly diminished. A reactivation factor of 1.3 only was found for X-irradiated phages when host cells were treated with UV-irradiation. The low Weigle reactivation of X-ray treated phages compared to UV-treatment was found to be due to a diminished absorption capacity, as demonstrated by the determination of free non-absorbed phages by filtration of radioactive-labelled phage-host-complexes. Reactivation studies on X-irradiated phages with various host bacteria of different radiation sensitivities confirm this finding.

  17. Toward picosecond time-resolved X-ray absorption studies of interfacial photochemistry

    Science.gov (United States)

    Gessner, Oliver; Mahl, Johannes; Neppl, Stefan

    2016-05-01

    We report on the progress toward developing a novel picosecond time-resolved transient X-ray absorption spectroscopy (TRXAS) capability for time-domain studies of interfacial photochemistry. The technique is based on the combination of a high repetition rate picosecond laser system with a time-resolved X-ray fluorescent yield setup that may be used for the study of radiation sensitive materials and X-ray spectroscopy compatible photoelectrochemical (PEC) cells. The mobile system is currently deployed at the Advanced Light Source (ALS) and may be used in all operating modes (two-bunch and multi-bunch) of the synchrotron. The use of a time-stamping technique enables the simultaneous recording of TRXAS spectra with delays between the exciting laser pulses and the probing X-ray pulses spanning picosecond to nanosecond temporal scales. First results are discussed that demonstrate the viability of the method to study photoinduced dynamics in transition metal-oxide semiconductor (SC) samples under high vacuum conditions and at SC-liquid electrolyte interfaces during photoelectrochemical water splitting. Opportunities and challenges are outlined to capture crucial short-lived intermediates of photochemical processes with the technique. This work was supported by the Department of Energy Office of Science Early Career Research Program.

  18. 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

  19. Simulation study of spatial resolution in phase-contrast X-ray imaging with Takagi-Taupin equation

    CERN Document Server

    Koyama, I

    2003-01-01

    To evaluate attainable spatial resolution of phase-contrast X-ray imaging using an LLL X-ray interferometer with a thin crystal wafer, a computer simulation study with Takagi-Taupin equation was performed. Modulation transfer function of the wafer for X-ray phase was evaluated. For a polyester film whose thickness is 0.1 mm, it was concluded that the spatial resolution can be improved up to 3 mu m by thinning the wafer, under our experimental condition.

  20. Quality of outpatient care of children and adolescents in conventional X-ray diagnosis - a pilot study

    International Nuclear Information System (INIS)

    Purpose: The aim of the study was to evaluate the current quality of the outpatient radiodiagnostic care of children and adolescents as demonstrated for the example of conventional X-ray procedures. Materials and Methods: A consecutive series of 166 outpatient X-rays, selected by fixed criteria, was analysed according to both diagnostic aspects and radiation protection. Results: The X-rays examined were mainly gathered from orthopedic and radiological practices and from hospital radiological departments. The majority of these outpatient X-rays showed significant deficiencies regarding exposure, appropriate field size, and focussing or positioning of the patient. After the evaluation of the 166 X-rays by a total-score, 25% (42/166) of the X-rays were considered to be diagnostically insufficient. Conclusions: Improvements in outpatient radiodiagnostics are necessary to ensure adequate radiodiagnostic care of children and adolescents. (orig.)