National Synchrotron Light Laboratory Research Articles

Reproducibility of Global and Local Reconstruction of Three-Dimensional Micro-Computed Tomography of Iliac Crest Biopsies

Variation in computed tomography (CT) image gray-scale and spatial geometry due to specimen orientation, magnification, voxel size, differences in X-ray photon energy and limited field-of-view during the scan, were evaluated in repeated micro-CT scans of iliac crest biopsies and test phantoms. Using the micro-CT scanner on beamline X2B at the Brookhaven National Laboratory's National Synchrotron Light Source, 3-D micro-CT images were generated. They consisted of up to 1024 x 2400(2), 4-microm cubic voxels, each with 16-bit gray-scale. We also reconstructed the images at 16-, 32-, and 48-microm voxel resolution. Scan data were reconstructed from the complete profiles using filtered back-projection and from truncated profiles using profile-extension and with a Local reconstruction algorithm. Three biopsies and one bone-like test phantom were each rescanned at three different times at annual intervals. For the full-data-set reconstructions, the reproducibility of the estimates of mineral content of bone at mean bone opacity value, was +/-28.8, i.e., 2.56%, in a 4-microm cubic voxel at the 95% confidence level. The reproducibility decreased with increased voxel size. The interscan difference in imaged bone volume ranged from 0.86 4-microm 0.64% at 4-microm voxel resolution, and 2.64 4-microm 2.48% at 48 microm.

Characterization of osteoporotic bone structures by bidimensional images through x‐ray microfluorescence with synchrotron radiation

AbstractThe objective of this study was to characterize the bone structures of the femoral head and the cortical and trabecular regions, using two‐dimensional images produced by x‐ray microfluorescence, which supplies information about the superficial distribution of minerals. The measurements were performed in the standard geometry with 45 incidence, and excitation with a white beam and an optical capillary with 20 µm diameter collimation in the x‐ray fluorescence (XRF) beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). The results show that both the concentration and the distribution of the minerals vary significantly among the groups, mostly in relation to the element calcium, depending on the location and bone site. Copyright © 2007 John Wiley & Sons, Ltd.

Evaluation of bone mineral density loss using an X-ray powder diffractometer and synchrotron radiation at LNLS—Brazil

X-ray coherent scattering can be attractive for noninvasive quantification and to provide complementary information to discriminate between cortical and trabecular bone tissue. Both laboratory X-ray source and synchrotron have been used in the study of the potential application of scattering information for imaging of mineral content in bone. Initially, a powder diffractometer was used. The scattering profiles were obtained using a Shimadzu DRX 6000 diffractometer at the Nuclear Instrumentation Laboratory, Brazil. The second coherent X-ray scattering measurements were carried out at the X-Ray Diffraction (XRD1) beamline located at the D12A bending-magnet port at the National Synchrotron Light Laboratory (LNLS) in Campinas, Brazil. The results obtained on the two machines are compared to each other. For both experiments, a good agreement can be seen between the bone calibration curves plotted. Although the data obtained from both machines were produced with the same statistical uncertainty, the acquisition time using synchrotron radiation was about 10 times smaller.

Mail-in crystallography program at Brookhaven National Laboratory's National Synchrotron Light Source

For the last six years, the Macromolecular Crystallography Research Resource (PXRR) has been providing mail-in access to several beamlines at the National Synchrotron Light Source (NSLS) for X-ray diffraction. This program is available at no charge for academic users from the US and around the world. This service has fostered a new paradigm for collaborations between the local staff scientists and synchrotron users. It also accelerates the innovation of new productivity tools, which benefit users who come to NSLS beamlines as well as those who use the mail-in program.

Analysis of beers from Brazil with synchrotron radiation total reflection X-ray fluorescence

In this study the concentrations of P, S, Cl, K, Ca, Mn, Fe, Zn and Br in twenty-nine brands of national and international beers were determined by synchrotron radiation total reflection X-ray fluorescence analysis (SR-TXRF). The results were compared with the limits established by the Brazilian legislation and the nutritional values established by National Agricultural Library (NAL, USA). The measurements were performed at the X-Ray Fluorescence Beamline at Brazilian National Synchrotron Light Laboratory, in Campinas, Sao Paulo, Brazil, using a polychromatic beam for excitation. A small volume of 5 ml of beers containing an internal standard used to correct geometry effects was analyzed without pretreatment. The measuring time was 100 seconds and the detection limits obtained varied from 1 mg . l-1 for Mn and Fe to 15 mg . l-1 for P.

Elucidando os estados de oxidação do nitrogênio através da espectroscopia de absorção de raios-X na borda K do nitrogênio

The potentialities of X-ray Absorption Near Edge Spectroscopy (XANES) of the N K edge (N K) obtained with the spherical grating monochromator beam line at the Brazilian National Synchrotron Light Laboratory are explored in the investigation of poly(aniline), nanocomposites and dyes. Through the analysis of N K XANES spectra of conducting polymers and many other dye compounds that are dominated by 1s®p* transitions, it was possible to correlate the band energy value with the nitrogen oxidation states. An extensive N K XANES spectral database was obtained, thus permitting the elucidation of the nature of different nitrogens present in the intercalated conducting polymers.

Brazilian synchrocyclotron light

ABSTRACT The National Synchrotron Light Laboratory (LNLS) is one of the ten institutes linked to the National Council for Scientific and Technological Development (CNPq) and one of the most important investments made in the last two decades by the Brazilian federal government in civil Science and Technology (S&T). The issue I address involves the understanding of how the Synchrotron Project materializes. Such objective implies revisiting the long negotiation process, which lasts through two political regimes and five different governments; and which faced resistance even from scientists and researchers My hypothesis is that the institutionalization of the Synchrotron Project becomes viable thanks to a process that goes from the permeability of the LNLS negotiation process to the imposed transformations by the transition to the democratic regime.

Trace element concentration in São Francisco River water using STXRF and PIXE techniques

Trace element concentrations in water from Sao Francisco River using Particle Induced X-ray Emission (PIXE) and Synchroton Total Reflection X-ray Fluorescence (STXRF) techniques are measured. The main objective of this work was to characterize and to monitor the trace elements in the water of Sao Francisco River, as well as to provide valuable information about the levels of metallic ions pollutants. Water samples were collected monthly at five locations along the course of the river from July 2003 to April 2004. As an internal standard, 11.6 ppm of Yttrium was added to 10 ml of the water sample. The PIXE and TXRF measurements were performed at the Ion Beams and Materials Laboratory (LAMFI) and the Brazilian National Synchrotron Light Laboratory (LNLS), using a proton beam and a polychromatic X-ray beam, respectively. Si(Li) detectors were used to collect the X-ray spectra. Due to the excellent detection limits of the PIXE and STXRF analysis, up to 15 elements were quantified. The highest total content of Cr, As, Cu and Zn detected in river water are above the limits recommended by the environmental legislation.

Coherent scattering X-ray imaging at the Brazilian National Synchrotron Laboratory: Preliminary breast images

The angular distribution of coherent scatter (low-momentum transfer) carries information about atomic structures, resulting in a pattern, which can be used to reconstruct a series of images. Coherent-scatter computed tomography is a novel imaging method developed to produce cross-sectional images based on the X-ray diffraction properties of an object. A different approach to coherent X-ray imaging is possible by fixing the detector at a given scatter angle θ , which produces an interference peak and then, carried out a tomography in the standard way. The cross-sectional images obtained allow determining the spatial dependence of coherent scatter cross-section of selected volume elements of inhomogeneous, extend objects for a single predetermined value of θ of interest, leading to a simplification of the data processing and the complexity of the apparatus. This work presents preliminary coherent scattering images carried out at the X-ray Diffraction beamline of the National Synchrotron Light Laboratory in Campinas, Brazil. The specimens were excised human breast tissues fixed in formaline. No frozen procedure was used in order to minimize preferred orientation during sample preparation. About 1 mm thick slices cut from each of the fresh samples were mounted in frames without windows and placed on a translator to allow acquisition of scattering spectra. Cylinders containing healthy and cancerous (infiltrating ductal carcinoma) breast tissues were imagined at the characteristic angle for adipose tissue. Transmission and coherent scatter images are compared.

An inelastic X-ray scattering spectrometer at LNLS.

A high-resolution spectrometer aimed at performing experiments of inelastic X-ray scattering by electronic excitations is described. The spectrometer has been installed at the D12A-XRD1 beamline of the National Synchrotron Light Laboratory (LNLS), in Campinas, Brazil. Synchrotron radiation is monochromated to about 6 keV and focused horizontally onto the sample by a sagittally focusing Si(111) double-crystal monochromator in non-dispersive setting. The spectrometer operates in Rowland circle geometry and is based on a focusing Si(333) analyser in near-backdiffraction geometry for energy analysis of inelastically scattered photons. The analyser works at a fixed Bragg angle, so energy transfers are obtained by varying the incident photon energy. A relative energy resolution of the whole spectrometer of approximately 1.5 x 10(-4) at 5.93 keV has been achieved. As an example of application, inelastic X-ray scattering by plasmon excitation in polycrystalline Be was measured. Test results demonstrate that inelastic X-ray scattering experiments with eV energy resolution and an acceptable counting rate are feasible at the LNLS when focused on plasmon and particle-hole excitations.

Microscopic X-ray fluorescence analysis of human dental calculus using synchrotron radiation

In this work, new results of one- and two-dimensional spatial distributions of major, minor and trace elements of human dental calculus are presented. X-ray fluorescence induced by a synchrotron radiation source was used. The measurements were carried out in the X-ray microprobe station mounted at the X-ray fluorescence beamline of the Brazilian National Synchrotron Light Laboratory (LNLS). Two-dimensional distributions show that calcium, the major element in this type of sample, has a uniform pattern over the mapped area, while trace elements are non-homogeneously distributed. By means of different linear scans along the growing axis of the dental calculus, a markedly spatial correlation between Cu and Zn was found. A semi-quantitative analysis for Cu and Zn was performed by means of calibration curves using appropriate fabricated standards. The concentration values found for these metals were higher than those obtained in conventional bulk analysis. It was observed that these metals accumulated preferentially in the subgingival part of the calculus, near the tooth surface. These results indicate that the mineralization processes, which take place for both type of calculus, are essentially different.

Analysis of mineral water from Brazil using total reflection X-ray fluorescence by synchrotron radiation

The total reflection X-ray fluorescence using synchrotron radiation (SRTXRF) has become a competitive technique for the determination of trace elements in samples that the concentrations are lower than 100 ng ml −1. In this work, thirty-seven mineral waters commonly available in supermarkets of Rio de Janeiro, Brazil, were analyzed by SRTXRF. The measurements were performed at the X-Ray Fluorescence Beamline at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo, using a polychromatic beam with maximum energy of 20 keV for the excitation. Standard solutions with gallium as internal standard were prepared for calibration of the system. Mineral water samples of 10 μl were added to Perspex sample carrier, dried under infrared lamp and analyzed for 200 s measuring time. It was possible to determine the concentrations of the following elements: Si, S, K, Ca, Ti, Cr, Mn, Ni, Cu, Zn, Ge, Rb, Sr, Ba and Pb. The elemental concentration values were compared with the limits established by the Brazilian legislation.

Elemental mapping of teeth using μSRXRF

Human teeth were analysed by X-ray microfluorescence analysis using synchrotron radiation (μSRXRF). The aim of this work was to study the elemental distribution for Ca, Zn and Sr along the dental regions, enamel, dentine and pulp from patterns of relative fluorescence intensities. The measurements were performed in standard geometry of 45° incidence, exciting with a white beam and using a conventional system collimation (orthogonal slits) in the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). The results show that Ca distribution is quite constant and it is independent of the tooth type and individuals characteristics. An increase of the Zn concentration was found for the pulp region and for untreated carious areas. Ca and Sr distributions show a similar behavior.

Setup for in situ WAXS/SAXS studies of the formation and growth of Bi nanodroplets and the melting of Bi nanocrystals using synchrotron radiation

The setup was designed for in situ studies of structural transformations in materials at high temperatures. It makes possible simultaneous recording of wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS) spectra from room temperature up to 1000 °C. The setup was installed in the National Synchrotron Light Laboratory SAXS beamline. It was applied to in situ studies of several structural transformations such as the formation and growth of liquid Bi nanodroplets embedded in a B 2O 3–Na 2O glass and the melting of Bi nanocrystals dispersed in the same glass matrix.

Ion nitriding of stainless steels. Real time surface characterization by synchrotron X-ray diffraction

Three types of steels with different Cr and Ni contents were ion nitrided by means of 100 Hz glow discharge in a N 2-H 2 gas mixture using a special reactor installed in the SAXS beamline of the National Synchrotron Light Laboratory (LNLS), Campinas, Brazil. The studied materials were austenitic (AISI 304 and DIN WNr 1.4882) and ferritic (SAE HNV3) steels. The experimental setup allowed the study of the structural evolution in situ and in real time of steel surfaces during the ion nitriding process itself, using the X-ray diffraction technique. The use of a well-collimated and intense X-ray beam of the synchrotron radiation source allowed successive short exposure diffraction patterns to be taken. A very fast ion nitriding process was verified for the three studied steels. The measurements concerning the nitriding kinetics of both austenitic steels indicated the formation of an S phase. Nevertheless, while in the AISI 304 steel, the S phase was later replaced by a compound layer of γ′-Fe 4N, in the DIN WNr 1.4882 steel, the S phase remained until the end of the nitriding process. In both cases, CrN was formed during the process. Instead, in the ferritic SAE HNV3 steel, the S and CrN phases were not observed.

Synchrotron SAXS Studies of Nanostructured Materials and Colloidal Solutions: A Review

Structural characterisations using the SAXS technique in a number of nanoheterogeneous materials and liquid solutions are reviewed. The studied systems are protein (lysozyme)/water solutions, colloidal ZnO particles/water sols, nanoporous NiO-based xerogels, hybrid organic-inorganic siloxane-PEG and PPG nanocomposites and PbTe semiconductor nanocrystals embedded in a glass matrix. These investigations also focus on the transformations of time-varying structures and on structural changes related to variations in temperature and composition. The reviewed investigations aim at explaining the unusual and often interesting properties of nanostructured materials and solutions. Most of the reported studies were carried out using the SAXS beamline at the National Synchrotron Light Laboratory (LNLS), Campinas, Brazil.

Phase transitions in Nb rich coating produced by laser alloying: a synchrotron radiation diffraction study

A great variety of studies have been performed in order to develop new materials with high performance in many adverse conditions such as wear and corrosive environment coupled with high temperatures and high stress levels. A strong scientific and technical effort is currently dedicated to develop wear and corrosion resistant surfaces to provide components having good behavior in such extreme working conditions, we have chosen laser alloying and prepared Nb rich coatings upon a nodular cast iron microstructure. The new tailored material is in fact a composite having a very hard coating covering a traditional iron base material. If the material is submitted for thermal cycling, it is imperative to know the phase transformations during heating/cooling cycles, as well as, during long periods of permanence at high temperatures. According to these guidelines, we performed an X-ray diffraction (XRD) study using the XRD beam line of the National Synchrotron Light Laboratory (LNLS, Brazil). The analysis of the XRD pattern indicates the presence of niobium and niobium carbides (Nb, NbC, Nb 2C) from room temperature up to 750 °C.

X-ray diffraction microtomography using synchrotron radiation

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

Composition fluctuations in the demixed supercooled liquid state of Zr41Ti14Cu12.5Ni10Be22.5: a combined ASAXS and SANS study

This chapter contains basic concepts and applications of wide-angle X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS) to studies of nanostructured materials. The first part includes an introduction to the technique of X-ray powder diffraction (XPD), which is commonly applied to phase identification of powdered materials, characterization of unit cells, determinations of lattice parameters and, in some cases, also coordinates of atoms inside the unit cells. The main aspect described here is the analysis of the shape of X-ray diffraction peak profiles, which allows one to determine additional and also valuable structural information of nanomaterials, such as average crystallite sizes and crystallite microstrains. Detailed deductions of the equations used for different applications of X-ray diffraction and basic concepts of crystallography (such as those related to symmetries, Bravais and reciprocal lattices, etc.) are not described. The second part presents the basic equations related to the SAXS method and their applications to several biological systems (proteins in solution). Classical SAXS is an experimental procedure that is employed in transmission mode and is also applied to the study of many nanostructured inorganic materials. The third part includes two variants of the classical SAXS procedure, namely grazing incidence small-angle X-ray scattering (GISAXS) and anomalous small-angle X-ray scattering (ASAXS). The basic concepts of the GISAXS method and several applications to studies of nanostructured materials deposited on flat substrates and buried nanostructures are presented. The basic concepts of the ASAXS method are described, together with its applications to complex materials that cannot be properly studied using the classical SAXS technique, such as, for example, materials modeled by three phases with different electron densities. Most of the experiments described in this chapter were performed by the authors using X-ray beam lines of the National Synchrotron Light Laboratory (LNLS), Campinas, Brazil.

SRXRF analysis with spatial resolution of dental calculus

This work presents elemental-composition studies of dental calculus by X-ray fluorescence analysis using synchrotron radiation. The intrinsic characteristics of synchrotron light allow for a semi-quantitative analysis with spatial resolution. The experiments were carried out in the high-vacuum station of the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). All the measurements were performed in conventional geometry (45°+45°) and the micro-collimation was attained via a pair of orthogonal slits mounted in the beamline. In this way, pixels of 50 μm×50 μm were obtained keeping a high flux of photons on the sample. Samples of human dental calculus were measured in different positions along their growing axis, in order to determine variations of the compositions in the pattern of deposit. Intensity ratios of minor elements and traces were obtained, and linear profiles and surface distributions were determined. As a general summary, we can conclude that μXRF experiments with spatial resolution on dental calculus are feasible with simple collimation and adequate positioning systems, keeping a high flux of photon. These results open interesting perspectives for the future station of the line, devoted to μXRF, which will reach resolutions of the order of 10 μm.