Science.gov

Sample records for adsorption powder x-ray

  1. X-ray characterization by energy-resolved powder diffraction

    NASA Astrophysics Data System (ADS)

    Cheung, G.; Hooker, S. M.

    2016-08-01

    A method for single-shot, nondestructive characterization of broadband x-ray beams, based on energy-resolved powder diffraction, is described. Monte-Carlo simulations are used to simulate data for x-ray beams in the keV range with parameters similar to those generated by betatron oscillations in a laser-driven plasma accelerator. The retrieved x-ray spectra are found to be in excellent agreement with those of the input beams for realistic numbers of incident photons. It is demonstrated that the angular divergence of the x rays can be deduced from the deviation of the detected photons from the Debye-Scherrer rings which would be produced by a parallel beam. It is shown that the angular divergence can be measured as a function of the photon energy, yielding the angularly resolved spectrum of the input x-ray beam.

  2. X-ray powder diffraction study of polytetrafluoroethylene

    SciTech Connect

    Lebedev, Yu. A. Korolev, Yu. M.; Polikarpov, V. M.; Ignat'eva, L. N.; Antipov, E. M.

    2010-07-15

    Samples of polytetrafluoroethylene were studied by X-ray diffraction. A quantitative X-ray powder diffraction analysis of three components of the polymer was performed for the first time. All samples of polytetrafluoroethylene were found to be three-phase and consist of one crystalline and two amorphous phases. One of the amorphous phases is composed of low-molecular-weight products. The structure of the latter phase was established for the first time by X-ray diffraction methods and computer simulation.

  3. Powder X-ray Diffraction Using the Omega Laser

    NASA Astrophysics Data System (ADS)

    Eggert, Jon; Rygg, Ryan; Smith, Raymond; Bastea, Marina; Ping, Yuan; Shepherd, Ronnie; Collins, Gilbert

    2009-06-01

    The past several years have seen dramatic improvements in dynamic ramp-compression experiments to measure stress-density using laser and pulsed-power drivers. Goals for future experiments center on achieving pressures over 1 TPa (10 Mbar), while keeping the samples in a solid phase and applying additional diagnostics to probe the nature of these states. X-ray scattering is a natural probe for such studies due to the copious x-ray energy produced by laser sources. Such experiments allow studies of the crystal structure, texture, strength, and possibly temperature of ramp-compressed solids at unprecedented density. With this in mind we have developed a powder x-ray diffraction diagnostic fielded at the Omega laser. We will report our results on ramp-driven iron, tin and copper. This work performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

  4. Parts per Million Powder X-ray Diffraction.

    PubMed

    Newman, Justin A; Schmitt, Paul D; Toth, Scott J; Deng, Fengyuan; Zhang, Shijie; Simpson, Garth J

    2015-11-01

    Here we demonstrate the use of second harmonic generation (SHG) microscopy-guided synchrotron powder X-ray diffraction (PXRD) for the detection of trace crystalline active pharmaceutical ingredients in a common polymer blend. The combined instrument is capable of detecting 100 ppm crystalline ritonavir in an amorphous hydroxypropyl methylcellulose matrix with a high signal-to-noise ratio (>5000). The high spatial resolution afforded by SHG microscopy allows for the use of a minibeam collimator to reduce the total volume of material probed by synchrotron PXRD. The reduction in probed volume results in reduced background from amorphous material. The ability to detect low crystalline loading has the potential to improve measurements in the formulation pipeline for pharmaceutical solid dispersions, for which even trace quantities of crystalline active ingredients can negatively impact the stability and bioavailability of the final drug product.

  5. Powder X-ray diffraction laboratory, Reston, Virginia

    USGS Publications Warehouse

    Piatak, Nadine M.; Dulong, Frank T.; Jackson, John C.; Folger, Helen W.

    2014-01-01

    The powder x-ray diffraction (XRD) laboratory is managed jointly by the Eastern Mineral and Environmental Resources and Eastern Energy Resources Science Centers. Laboratory scientists collaborate on a wide variety of research problems involving other U.S. Geological Survey (USGS) science centers and government agencies, universities, and industry. Capabilities include identification and quantification of crystalline and amorphous phases, and crystallographic and atomic structure analysis for a wide variety of sample media. Customized laboratory procedures and analyses commonly are used to characterize non-routine samples including, but not limited to, organic and inorganic components in petroleum source rocks, ore and mine waste, clay minerals, and glassy phases. Procedures can be adapted to meet a variety of research objectives.

  6. X-ray powder data for uranium and thorium minerals

    USGS Publications Warehouse

    Frondel, Clifford; Riska, Daphne; Frondel, Judith Weiss

    1956-01-01

    The U.S. Geological Survey has in preparation a comprehensive volume on the mineralogy of uranium and thorium. This work has been done as part of a continuing systematic survey of data on uranium and thorium minerals on behalf of the Division of Raw Materials, U.S. Atomic Energy Commission. Pending publication of this volume and in response to a widespread demand among workers in uranium and thorium mineralogy, the X-ray powder diffraction data for the known minerals that contain uranium or thorium as an essential constituent are presented here. The coverage is complete except for a few minerals for which there are no reliable data owing to lack of authentic specimens. With the exception of that for ianthinite, the new data either originated in the Geological Survey or in the Mineralogical Laboratory of Harvard University. Data from the literature or other sources were cross-checked against the files of standard patterns of these laboratories; the sources are indicated in the references. Data not accompanied by a reference were obtained from films in the Harvard Standard File and cross-checked as to the identity of the film with the Geological Survey's file. Minor differences can be expected in the d-spacings reported for the same specimens by different investigators because of the manner of preparation of the mount, the conditions of X-ray irradiation, and the method of photography and measurement of the film or chart. The Harvard and Geological Survey data all were obtained from films taken in 114-mm diameter cameras, using either ethyl cellulose and toluene or collodion spindle mounts and Straumanis-type film mounting. Unless otherwise indicated all patterns were taken with copper radiation (Kα 1.5418 A.) and nickel filter and data are given in Angstrom units. The d-spacings are not corrected for film shrinkage. The correction ordinarily is small and in general is less than either the variation in spacing arising from differences in experimental technique of

  7. Synchrotron Powder X-ray Diffraction Study of the Structure and Dehydration Behavior of Sepiolite

    NASA Astrophysics Data System (ADS)

    Post, J. E.; Bish, D. L.; Heaney, P. J.

    2006-05-01

    Sepiolite is a hydrous Mg-silicate clay mineral with fibrous morphology that typically occurs as fine-grained, poorly crystalline masses. It occurs in a wide variety of geological environments and has been mined for centuries because of its many uses, e.g. in the pharmaceutical, fertilizer, and pesticide industries. Its versatile functionality derives from the large surface area and microporosity that are characteristic of the material. In recent years, sepiolite has received considerable attention with regard to the adsorption of organics, for use as a support for catalysts, as a molecular sieve, and as an inorganic membrane for ultrafiltration. Because of its fine-grained and poorly crystalline nature, it has not been possible to study sepiolite's crystal structure using single-crystal X-ray diffraction methods, and consequently many details of the structure are still not well known. In this study, Rietveld refinements using synchrotron powder X-ray diffraction data were used to investigate the crystal structure and dehydration behavior of sepiolite from Durango, Mexico. The room- temperature (RT) sepiolite structure in air compares well with previous models but reveals an additional zeolitic water site. The RT structure under vacuum retained only ~1/8 of the zeolitic water and the volume decreased 1.3%. Real-time, temperature-resolved synchrotron powder X-ray diffraction data and Rietveld refinements were used to investigate the behavior of the sepiolite structure from 300 to 925 K. Rietveld refinements revealed that most of the zeolitic water is lost by ~390 K, accompanied by a decrease in the a and c unit-cell parameters. Above ~600 K the sepiolite structure folds as one-half of the crystallographically bound water is lost. Rietveld refinements of the "anhydrous" sepiolite structure reveal that, in general, unit-cell parameters a, b, â and volume steadily decrease with increasing temperature; there is an obvious change in slope at ~820 K suggesting a phase

  8. Characterization of ceramic powders by an X-ray measuring method

    NASA Technical Reports Server (NTRS)

    Ziegler, B.

    1983-01-01

    X-ray line broadening analysis gives quantitative data on structural changes of ceramic powders after different processing steps. Various Al2O3 powders were investigated and the following points are discussed on the basis of these results: X-ray line broadening analysis, structural changes during grinding, structural changes during annealing, influence of structural properties on sintering behavior and application of line broadening analysis to quality control of powders.

  9. Kinetic products in coordination networks: ab initio X-ray powder diffraction analysis.

    PubMed

    Martí-Rujas, Javier; Kawano, Masaki

    2013-02-19

    Porous coordination networks are materials that maintain their crystal structure as molecular "guests" enter and exit their pores. They are of great research interest with applications in areas such as catalysis, gas adsorption, proton conductivity, and drug release. As with zeolite preparation, the kinetic states in coordination network preparation play a crucial role in determining the final products. Controlling the kinetic state during self-assembly of coordination networks is a fundamental aspect of developing further functionalization of this class of materials. However, unlike for zeolites, there are few structural studies reporting the kinetic products made during self-assembly of coordination networks. Synthetic routes that produce the necessary selectivity are complex. The structural knowledge obtained from X-ray crystallography has been crucial for developing rational strategies for design of organic-inorganic hybrid networks. However, despite the explosive progress in the solid-state study of coordination networks during the last 15 years, researchers still do not understand many chemical reaction processes because of the difficulties in growing single crystals suitable for X-ray diffraction: Fast precipitation can lead to kinetic (metastable) products, but in microcrystalline form, unsuitable for single crystal X-ray analysis. X-ray powder diffraction (XRPD) routinely is used to check phase purity, crystallinity, and to monitor the stability of frameworks upon guest removal/inclusion under various conditions, but rarely is used for structure elucidation. Recent advances in structure determination of microcrystalline solids from ab initio XRPD have allowed three-dimensional structure determination when single crystals are not available. Thus, ab initio XRPD structure determination is becoming a powerful method for structure determination of microcrystalline solids, including porous coordination networks. Because of the great interest across scientific

  10. Quality experimental and calculated powder x-ray diffraction

    SciTech Connect

    Sullenger, D.B.; Cantrell, J.S.; Beiter, T.A.; Tomlin, D.W.

    1996-08-01

    For several years, we have submitted quality powder XRD patterns to the International Centre for Diffraction Data for inclusion as reference standards in their Powder Diffraction File. The procedure followed is described; examples used are {beta}-UH{sub 3}, {alpha}- BaT{sub 2}, alpha-lithium disilicate ({alpha}-Li{sub 2}Si{sub 2}O{sub 5}), and 2,2`,4,4`,6,6`hexanitroazobenzene-III (HNAB-III).

  11. Synchrotron x-ray powder diffraction studies in pulsed magnetic fields

    SciTech Connect

    Frings, P.; Vanacken, J.; Detlefs, C.; Duc, F.; Lorenzo, J. E.; Nardone, M.; Billette, J.; Zitouni, A.; Bras, W.; Rikken, G. L. J. A.

    2006-06-15

    X-ray powder diffraction experiments under pulsed magnetic fields were carried out at the DUBBLE beamline (BM26B) at the ESRF. A mobile generator delivered 110 kJ to the magnet coil, which was sufficient to generate peak fields of 30 T. A liquid He flow cryostat allowed us to vary the sample temperature accurately between 8 and 300 K. Powder diffraction patterns of several samples were recorded using 21 keV monochromatic x-rays and an on-line image plate detector. Here we present the first results on the suppression of the Jahn-Teller structural distortion in TbVO{sub 4} by magnetic field. These data clearly demonstrate the feasibility of x-ray powder diffraction experiments under pulsed magnetic fields with relatively inexpensive instrumentation.

  12. Surface state analysis of wet ground silicon nitride powders by x-ray photoelectron spectroscopy

    SciTech Connect

    Kameshima, Yoshikazu; Yasumori, Atsuo; Okada, Kiyoshi

    1995-09-01

    Three kinds of silicon nitride powders, i.e. as-prepared direct-nitridation powder, HF-treated direct-nitridation powder, and as-prepared imide decomposition powder, were wet ground by ball milling in water and the surface state change due to the grinding was examined by X-ray photoelectron spectroscopy (XPS) and X-ray Auger electron spectroscopy (XAES). The thickness of the oxidized surface layer of the powder was calculated from the peak area ratio and the chemical composition was evaluated from the Auger parameter (AP). Surface oxidized phase amount gradually increased with longer milling time and the thickness increased almost three times after 7 days milling, compared to as those of the unground samples. Chemical composition of the oxidized phase formed by the grinding was pure silica irrespective to the samples, although those of the oxidized phase in the unground samples differed among the samples.

  13. Synchrotron X-ray Powder Diffraction Studies in Pulsed Magnetic Fields

    SciTech Connect

    Detlefs, C.; Frings, P.; Duc, F.; Nardone, M.; Billette, J.; Zitouni, A.; Rikken, G. L. J. A.; Vanacken, J.; Lorenzo, J. E.; Bras, W.

    2007-01-19

    X-ray powder diffraction experiments under pulsed magnetic fields were carried out at the DUBBLE beamline (BM26B) at the ESRF. A mobile generator delivered 110kJ to the magnet coil, which was sufficient to generate peak fields of 30T. A liquid He flow cryostat allowed us to vary the sample temperature accurately between 8K and 300K.

  14. Monitoring model drug microencapsulation in PLGA scaffolds using X-ray powder diffraction

    PubMed Central

    Aina, Adeyinka; Gupta, Manish; Boukari, Yamina; Morris, Andrew; Billa, Nashiru; Doughty, Stephen

    2015-01-01

    The microencapsulation of three model drugs; metronidazole, paracetamol and sulphapyridine into Poly (dl-Lactide-Co-Glycolide) (PLGA) scaffolds were probed using X-ray Powder Diffraction (XRPD). Changes in the diffraction patterns of the PLGA scaffolds after encapsulation was suggestive of a chemical interaction between the pure drugs and the scaffolds and not a physical intermixture. PMID:27013917

  15. A compact high-resolution X-ray powder diffractometer

    PubMed Central

    Fewster, Paul F.; Trout, David R. D.

    2013-01-01

    A new powder diffractometer operating in transmission mode is described. It can work as a rapid very compact instrument or as a high-resolution instrument, and the sample preparation is simplified. The incident beam optics create pure Cu Kα1 radiation, giving rise to peak widths of ∼0.1° in 2θ in compact form with a sample-to-detector minimum radius of 55 mm, reducing to peak widths of <0.05° in high-resolution mode by increasing the detector radius to 240 mm. The resolution of the diffractometer is shown to be governed by a complex mixture of angular divergence, sample size, diffraction effects and the dimensions of the detector pixels. The data can be collected instantaneously, which combined with trivial sample preparation and no sample alignment, makes it a suitable method for very rapid phase identification. As the detector is moved further from the sample, the angular step from the pixel dimension is reduced and the resolution improves significantly for very detailed studies, including structure determination and analysis of the microstructure. The advantage of this geometry is that the resolution of the diffractometer can be calculated precisely and the instrumental artefacts can be analysed easily without a sample present. The performance is demonstrated with LaB6 and paracetamol, and a critical appraisal of the uncertainties in the measurements is presented. The instantaneous data collection offers possibilities in dynamic experiments. PMID:24282331

  16. X-ray study of interfacial interactions in highly milled Sn-Ge powders

    SciTech Connect

    Jayanetti, J.K.D.S.; Heald, S.M.; Tan, Z.

    1991-12-31

    We have studied possible structural changes occurring at the Sn/Ge interface of highly milled Sn/Ge composites. EXAFS and X-ray Diffraction measurements were made on mechanically milled powders having compositions ranging from 20 to 50 vol.% Sn. X-ray diffraction measurements indicate the increasing amorphization of Sn as the Sn content is decreased. EXAFS results indicate that this amorphous phase is due to the formation of an {alpha}-Sn/Ge alloy. The EXAFS from this alloy did not change significantly at the Sn melting point. X-ray diffraction measurements made at room temperature show a systematic decrease in the intensity of Sn peaks and broadening of Ge peaks with the decreasing Sn content.

  17. X-ray study of interfacial interactions in highly milled Sn-Ge powders

    SciTech Connect

    Jayanetti, J.K.D.S.; Heald, S.M.; Tan, Z.

    1991-01-01

    We have studied possible structural changes occurring at the Sn/Ge interface of highly milled Sn/Ge composites. EXAFS and X-ray Diffraction measurements were made on mechanically milled powders having compositions ranging from 20 to 50 vol.% Sn. X-ray diffraction measurements indicate the increasing amorphization of Sn as the Sn content is decreased. EXAFS results indicate that this amorphous phase is due to the formation of an {alpha}-Sn/Ge alloy. The EXAFS from this alloy did not change significantly at the Sn melting point. X-ray diffraction measurements made at room temperature show a systematic decrease in the intensity of Sn peaks and broadening of Ge peaks with the decreasing Sn content.

  18. Estimating mean crystallite size of magnetite using multivariate calibration and powder x-ray diffraction analysis.

    PubMed

    Lemes, Maykon A; Godinho, Mariana S; Rabelo, Denilson; Martins, Felipe T; Mesquita, Alexandre; Neto, Francisco N De Souza; Araujo, Olacir A; Oliveira, Anselmo E De

    2014-01-01

    Powder X-ray diffraction patterns for 29 samples of magnetite, acquired using a conventional diffractometer, were used to build PLS calibration-based methods and variable selection to estimate mean crystallite size of magnetite directly from powder X-ray diffraction patterns. The best IPLS model corresponds to the Bragg reflections at 35.4° (h k l = 3 1 1), 43.0° (h k l = 4 0 0), 53.6° (h k l = 4 2 2), and 57.0° (h k l = 5 1 1) in 2θ. The best model was a GA-PLS which produced a model with RMSEP of 0.9 nm, and a correlation coefficient of 0.9976 between mean crystallite sizes calculated using Williamson-Hall approach and the ones predicted by GA-PLS method. These results indicate that magnetite mean crystallite sizes can be predicted directly from Powder X-Ray Diffraction and multivariate calibration using PLS variable selection approach.

  19. Characterization of zeolite structure and fluorocarbon reactivity using solid state NMR and x-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Ciraolo, Michael Frank

    The research presented in this thesis involves a combination of techniques used to study the structure and interactions zeolites adsorbed with fluorocarbons. This research is specifically aimed at understanding the processes of adsorption, binding, and reactivity of fluorocarbons on cation exchanged faujasite type zeolites. The solid state ion exchange process has also been studied since it is one way to obtain materials with higher exchange levels, which has been shown to effect adsorption and catalytic activity. To improve the understanding of the adsorption and separation processes a time resolved in-situ synchrotron x-ray powder diffraction study has been undertaken. Since faujasite type zeolites have been found to be effective in separating mixtures of HFC-134 (CF2HCF2H) and HFC-134a (CFH2CF3) isomers, the adsorption of these fluorocarbons on NaY have been studied. It has been shown that both the extent of loading and the kinetics of the sorption process in molecular sieves can be followed using this technique. A model for the binding of hydrochlorofluorocarbon (HCFC) 124a (CF 2HCF2Cl) adsorbed on NaX at 100K has been determined using a combination x-ray and neutron powder diffraction and solid state NMR. Using Rietveld refinement of the diffraction data, the HCFC molecule was found localized in the zeolite cavities bound on either end by sodium cations in the SII and SIII' positions. The model is consistent with hydrogen bonding between the proton of the HCFC and the framework oxygen. The NMR results further confirm the model and are consistent with Na-F binding and HCFC-framework interactions. Solid-state MAS NMR, synchrotron X-ray powder diffraction and a mass spectrometer and gas chromatograph catalysis system have been used to study the reactivity of HCFC-124a (CF2HCF2Cl) on NaX, Zn 2+-exchanged NaX (ZnX) and Rb+-exchanged NaX (RbX). We have chosen to study HCFC-124a (CF2HCF2Cl) since HCFC-124a can undergo both dehydrofluorination and dehydrochlorination

  20. Synchrotron hard X-ray imaging of shock-compressed metal powders

    NASA Astrophysics Data System (ADS)

    Rutherford, Michael E.; Chapman, David J.; Collinson, Mark A.; Jones, David R.; Music, Jasmina; Stafford, Samuel J. P.; Tear, Gareth R.; White, Thomas G.; Winters, John B. R.; Drakopoulos, Michael; Eakins, Daniel E.

    2015-06-01

    This poster will present the application of a new, high-energy (50 to 250 keV) synchrotron X-ray radiography technique to the study of shock-compressed granular materials. Following plate-impact loading, transmission radiography was used to quantitatively observe the compaction and release processes in a range of high-Z metal powders (e.g. Fe, Ni, Cu). By comparing the predictions of 3D numerical models initialized from X-ray tomograms-captured prior to loading-with experimental results, this research represents a new approach to refining mesoscopic compaction models. The authors gratefully acknowledge the ongoing support of Imperial College London, EPSRC, STFC and the Diamond Light Source, and AWE Plc.

  1. [A quantitation method for andrographolide and dehydroandrographolide by X-ray powder diffraction Fourier fingerprint pattern technique].

    PubMed

    Gong, Ning-Bo; Lü, Li-Juan; Liu, Chao; Ma, Lin; Chen, Ruo-Yun; Lü, Yang

    2010-05-01

    The powder X-ray diffraction Fourier fingerprint pattern technique was used to develop a new quantitation method for the analysis of andrographolide and dehydroandrographolide. And the high performance liquid chromatography method was used to evaluate the quantity of andrographolide and dehydroandrographolide. The relationship of diffraction peak intensity and content of andrographolide and dehydroandrographolide was investigated. The powder X-ray diffraction Fourier fingerprint pattern analysis technique can be used to evaluate the quantity of andrographolide and dehydroandrographolide in the herb simultaneously.

  2. X-ray Spectromicroscopy Study of Protein Adsorption to a Polystyrene-Polylactide Blend

    SciTech Connect

    Leung, Bonnie; Hitchcock, Adam; Cornelius, Rena; Brash, John; Scholl, Andreas; Doran, Andrew

    2010-06-09

    Synchrotron-based X-ray photoemission electron microscopy (X-PEEM) was used to study the adsorption of human serum albumin (HSA) to polystyrene-polylactide (40:60 PS-PLA, 0.7 wt percent) thin films, annealed under various conditions. The rugosity of the substrate varied from 35 to 90 nm, depending on the annealing conditions. However, the characteristics of the protein adsorption (amounts and phase preference) were not affected by the changes in topography. The adsorption was also not changed by the phase inversion which occured when the PS-PLA substrate was annealed above Tg of the PLA. The amount of protein adsorbed depended on whether adsorption took place from distilled water or phosphate buffered saline solution. These differences are interpreted as a result of ionic strength induced changes in the protein conformation in solution.

  3. RbCa2Nb3O10 from X-ray powder data

    PubMed Central

    Liang, Zhen-Hua; Tang, Kai-Bin; Chen, Qian-Wang; Zheng, Hua-Gui

    2009-01-01

    Rubidium dicalcium triniobate(V), RbCa2Nb3O10, has been synthesized by solid-state reaction and its crystal structure refined from X-ray powder diffraction data using Rietveld analysis. The compound is a three-layer perovskite Dion–Jacobson phase with the perovskite-like slabs derived by termination of the three-dimensional CaNbO3 perovskite structure along the ab plane. The rubidium ions (4/mmm symmetry) are located in the inter­stitial space. PMID:21582979

  4. Quantification of Pharmaceutical Compounds Based on Powder X-Ray Diffraction with Chemometrics.

    PubMed

    Otsuka, Yuta; Ito, Akira; Matsumura, Saki; Takeuchi, Masaki; Pal, Suvra; Tanaka, Hideji

    2016-01-01

    We propose an approach for the simultaneous determination of multiple components in pharmaceutical mixed powder based on powder X-ray diffraction (PXRD) method coupled with chemometrics. Caffeine anhydrate, acetaminophen and lactose monohydrate were mixed at various ratios. The samples were analyzed by PXRD method in the ranges of 2θ=5.00-30.0 and 35.0-45.0 degrees. Obtained diffractograms were analyzed by conventional peak intensity method, multi curve resolution (MCR)-alternating least squares (ALS) method and partial least squares (PLS) method. Constructed PLS models can most accurately predict the concentrations among different methods used. Each regression vector of PLS correlates not only to the compound of interest but also to the coexisting compounds. The combination of PXRD and PLS methods is concluded to be powerful approach for analyzing multi components in pharmaceutical formulations. PMID:27477651

  5. Characterization by X-ray tomography of granulated alumina powder during in situ die compaction

    SciTech Connect

    Cottrino, Sandrine; Jorand, Yves Maire, Eric; Adrien, Jérôme

    2013-07-15

    Compaction process, the aim of which being to obtain green bodies with low porosity and small size, is often used before sintering treatment. Prior to die filling, the ceramic powder is generally granulated to improve flowability. However during compaction, density heterogeneity and critical size defects may appear due to intergranule and granule-die wall frictions. In this work, the influence of granule formulation on the compact morphology has been studied. To do so, a compaction setup was installed inside an X-ray tomography equipment so that the evolution of the compact morphology could be analysed during the whole compaction process. We have demonstrated that high humidity rate and the addition of binder in the granule formulation increase density heterogeneity and generate larger defects. - Highlights: • An original compaction set up was installed inside an X-Ray tomography equipment. • The compaction process of granulated ceramic powder is imaged. • The compact green microstructure is quantified and related to the compaction stages. • The most detrimental defects of dry-pressed parts are caused by hollow granules. • Formulations without binder allow a reduction of the number of large defects.

  6. An X-ray diffraction analysis of crystallised whey and whey-permeate powders.

    PubMed

    Nijdam, Justin; Ibach, Alexander; Eichhorn, Klaus; Kind, Matthias

    2007-11-26

    Amorphous whey, whey-permeate and lactose powders have been crystallised at various air temperatures and humidities, and these crystallised powders have been examined using X-ray diffraction. The most stable lactose crystal under normal storage conditions, alpha-lactose monohydrate, forms preferentially in whey and whey-permeate powders at 50 degrees C, provided sufficient moisture is available, whereas anhydrous beta-lactose and mixed anhydrous lactose crystals, which are unstable under normal storage conditions, form preferentially at 90 degrees C. Thus, faster crystallisation at higher temperatures is offset by the formation of lactose-crystal forms that are less stable under normal storage conditions. Very little alpha-lactose monohydrate crystallised in the pure lactose powders over the range of temperatures and humidities tested, because the crystallisation of alpha- and beta-lactose is considerably more rapid than the mutarotation of beta- to alpha-lactose in the amorphous phase and the hydration of alpha-lactose during crystallisation. Protein and salts hinder the crystallisation process, which provides more time for mutarotation and crystal hydration in the whey and whey-permeate powders. PMID:17719020

  7. X-ray Reflectivity Study of the Adsorption of Azacrown Ether at Liquid-liquid Interface

    SciTech Connect

    Wojciechowski, Kamil; Gutberlet, Thomas; Tikhonov, Aleksey; Kashimoto, Kaoru; Schlossman, Mark

    2010-03-16

    Adsorption of diaza-18-crown-6 ether substituted with two tetracosane (-C{sub 24}H{sub 49}) alkyl chains (ACE-24) was investigated at the liquid-liquid interface. X-ray reflectivity measurements determined the structure of a close-packed monolayer at the hexane-water interface, which is consistent with conclusions drawn indirectly from earlier interfacial tension measurements on similar molecules. These data provide further insights into the role of interfacial processes involving azacrown ethers in ion separation techniques such as the permeation liquid membrane.

  8. Investigation by laser induced breakdown spectroscopy, X-ray fluorescence and X-ray powder diffraction of the chemical composition of white clay ceramic tiles from Veliki Preslav

    NASA Astrophysics Data System (ADS)

    Blagoev, K.; Grozeva, M.; Malcheva, G.; Neykova, S.

    2013-01-01

    The paper presents the results of the application of laser induced breakdown spectroscopy, X-ray fluorescence spectrometry, and X-ray powder diffraction in assessing the chemical and phase composition of white clay decorative ceramic tiles from the medieval archaeological site of Veliki Preslav, a Bulgarian capital in the period 893-972 AC, well-known for its original ceramic production. Numerous white clay ceramic tiles with highly varied decoration, produced for wall decoration of city's churches and palaces, were found during the archaeological excavations in the old capital. The examination of fourteen ceramic tiles discovered in one of the city's monasteries is aimed at characterization of the chemical profile of the white-clay decorative ceramics produced in Veliki Preslav. Combining different methods and comparing the obtained results provides complementary information regarding the white-clay ceramic production in Veliki Preslav and complete chemical characterization of the examined artefacts.

  9. X-ray photoelectron spectroscopy (XPS) investigation of the surface film on magnesium powders.

    PubMed

    Burke, Paul J; Bayindir, Zeynel; Kipouros, Georges J

    2012-05-01

    Magnesium (Mg) and its alloys are attractive for use in automotive and aerospace applications because of their low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. Powder metallurgy may be a suitable solution for forming near-net-shape parts. However, sintering pure magnesium presents difficulties due to surface film that forms on the magnesium powder particles. The present work investigates the composition of the surface film that forms on the surface of pure magnesium powders exposed to atmospheric conditions and on pure magnesium powders after compaction under uniaxial pressing at a pressure of 500 MPa and sintering under argon at 600 °C for 40 minutes. Initially, focused ion beam microscopy was utilized to determine the thickness of the surface layer of the magnesium powder and found it to be ~10 nm. The X-ray photoelectron analysis of the green magnesium sample prior to sintering confirmed the presence of MgO, MgCO(3)·3H(2)O, and Mg(OH)(2) in the surface layer of the powder with a core of pure magnesium. The outer portion of the surface layer was found to contain MgCO(3)·3H(2)O and Mg(OH)(2), while the inner portion of the layer is primarily MgO. After sintering, the MgCO(3)·3H(2)O was found to be almost completely absent, and the amount of Mg(OH)(2) was also decreased significantly. This is postulated to occur by decomposition of the compounds to MgO and gases during the high temperature of sintering. An increase in the MgO content after sintering supports this theory.

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

    SciTech Connect

    Garg, Alka B.; Errandonea, D.

    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.

  11. Kinetics of Methane Hydrate Decomposition Studied via in Situ Low Temperature X-ray Powder Diffraction

    SciTech Connect

    Everett, Susan M; Rawn, Claudia J; Keffer, David J.; Mull, Derek L; Payzant, E Andrew; Phelps, Tommy Joe

    2013-01-01

    Gas hydrates are known to have a slowed decomposition rate at ambient pressure and temperatures below the melting point of ice termed self-preservation or anomalous preservation. As hydrate exothermically decomposes, gas is released and water of the clathrate cages transforms into ice. Two regions of slowed decomposition for methane hydrate, 180 200 K and 230 260 K, were observed, and the kinetics were studied by in situ low temperature x-ray powder diffraction. The kinetic constants for ice formation from methane hydrate were determined by the Avrami model within each region and activation energies, Ea, were determined by the Arrhenius plot. Ea determined from the data for 180 200 K was 42 kJ/mol and for 230 260 K was 22 kJ/mol. The higher Ea in the colder temperature range was attributed to a difference in the microstructure of ice between the two regions.

  12. Validation of powder X-ray diffraction following EN ISO/IEC 17025.

    PubMed

    Eckardt, Regina; Krupicka, Erik; Hofmeister, Wolfgang

    2012-05-01

    Powder X-ray diffraction (PXRD) is used widely in forensic science laboratories with the main focus of qualitative phase identification. Little is found in literature referring to the topic of validation of PXRD in the field of forensic sciences. According to EN ISO/IEC 17025, the method has to be tested for several parameters. Trueness, specificity, and selectivity of PXRD were tested using certified reference materials or a combination thereof. All three tested parameters showed the secure performance of the method. Sample preparation errors were simulated to evaluate the robustness of the method. These errors were either easily detected by the operator or nonsignificant for phase identification. In case of the detection limit, a statistical evaluation of the signal-to-noise ratio showed that a peak criterion of three sigma is inadequate and recommendations for a more realistic peak criterion are given. Finally, the results of an international proficiency test showed the secure performance of PXRD. PMID:22235791

  13. Fast X-ray powder diffraction on I11 at Diamond.

    PubMed

    Thompson, Stephen P; Parker, Julia E; Marchal, Julien; Potter, Jonathan; Birt, Adrian; Yuan, Fajin; Fearn, Richard D; Lennie, Alistair R; Street, Steven R; Tang, Chiu C

    2011-07-01

    The commissioning and performance characterization of a position-sensitive detector designed for fast X-ray powder diffraction experiments on beamline I11 at Diamond Light Source are described. The detecting elements comprise 18 detector-readout modules of MYTHEN-II silicon strip technology tiled to provide 90° coverage in 2θ. The modules are located in a rigid housing custom designed at Diamond with control of the device fully integrated into the beamline data acquisition environment. The detector is mounted on the I11 three-circle powder diffractometer to provide an intrinsic resolution of Δ2θ approximately equal to 0.004°. The results of commissioning and performance measurements using reference samples (Si and AgI) are presented, along with new results from scientific experiments selected to demonstrate the suitability of this facility for powder diffraction experiments where conventional angle scanning is too slow to capture rapid structural changes. The real-time dehydrogenation of MgH(2), a potential hydrogen storage compound, is investigated along with ultrafast high-throughput measurements to determine the crystallite quality of different samples of the metastable carbonate phase vaterite (CaCO(3)) precipitated and stabilized in the presence of amino acid molecules in a biomimetic synthesis process. PMID:21685682

  14. Study of polymorphism of Atenolol and Captopril antihypertensives using x-ray powder diffraction and Rietveld refinement

    NASA Astrophysics Data System (ADS)

    Sato, Juliana; Ferreira, Fabio

    2013-03-01

    Characterization of bulk drugs has become increasingly important in the pharmaceutical industry. X-ray powder diffractometry is an effective technique for the identification of crystalline solid-phase drugs. The technique is unique, since it combines specificity with a high degree of accuracy for the characterization of pharmaceuticals in solid state and is an especially useful method to describe the possible polymorphic behavior of drugs substances. In this work X-ray diffraction data have been obtained for two well-known antihypertensive drugs currently being administered in tablet form. They include atenolol and captopril. Atenolol and captopril were purchased from drugstore. The characterizations of the atenolol and captopril samples were carried out by FTIR spectroscopy and X-ray powder diffraction (XRPD). We would like to thank the Brazilian agencies CNPq and FAPESP for their financial support.

  15. Studies of clays and clay minerals using x-ray powder diffraction and the Rietveld method

    SciTech Connect

    Bish, D.L.

    1993-09-01

    The Rietveld method was originally developed (Rietveld, 1967, 1969) to refine crystal structures using neutron powder diffraction data. Since then, the method has been increasingly used with X-ray powder diffraction data, and today it is safe to say that this is the most common application of the method. The method has been applied to numerous natural and synthetic materials, most of which do not usually form crystals large enough for study with single-crystal techniques. It is the ability to study the structures of materials for which sufficiently large single crystals do not exist that makes the method so powerful and popular. It would thus appear that the method is ideal for studying clays and clay minerals. In many cases this is true, but the assumptions implicit in the method and the disordered nature of many clay minerals can limit titsapplicability. This chapter will describe the Rietveld method, emphasizing the assumptions important for the study of disordered materials, and it will outline the potential applications of the method to these minerals. These applications include, in addition to the refinement of crystal structures, quantitative analysis of multicomponent mixtures, analysis of peak broadening, partial structure solution, and refinement of unit-cell parameters.

  16. Neutron and X-ray powder diffraction study of skutterudite thermoelectrics

    DOE PAGES

    Wang, H.; Kirkham, M. J.; Watkins, T. R.; Payzant, E. A.; Salvador, J. R.; Thompson, A. J.; Sharp, J.; Brown, D.; Miller, D.

    2016-02-17

    N- and p-type filled-skutterudite materials prepared for thermoelectric power generation modules were analyzed by neutron diffraction at the POWGEN beam line of the Spallation Neutron Source (SNS) and X-ray diffraction (XRD). The skutterudite powders were processed by melt spinning, followed by ball milling and annealing. The n-type material consists of Ba–Yb–Co–Sb and the p-type material consists of Di–Fe–Ni–Sb or Di–Fe–Co–Sb (Di = didymium, an alloy of Pr and Nd). Powders for prototype module fabrication from General Motors and Marlow Industries were analyzed in this study. XRD and neutron diffraction studies confirm that both the n- and p-type materials have cubicmore » symmetry. Structural Rietveld refinements determined the lattice parameters and atomic parameters of the framework and filler atoms. The cage filling fraction was found to depend linearly on the lattice parameter, which in turn depends on the average framework atom size. Ultimately, this knowledge may allow the filling fraction of these skutterudite materials to be purposefully adjusted, thereby tuning the thermoelectric properties.« less

  17. Using Variable Temperature Powder X-Ray Diffraction to Determine the Thermal Expansion Coefficient of Solid MgO

    ERIC Educational Resources Information Center

    Corsepius, Nicholas C.; DeVore, Thomas C.; Reisner, Barbara A.; Warnaar, Deborah L.

    2007-01-01

    A laboratory exercise was developed by using variable temperature powder X-ray diffraction (XRD) to determine [alpha] for MgO (periclase)and was tested in the Applied Physical Chemistry and Materials Characterization Laboratories at James Madison University. The experiment which was originally designed to provide undergraduate students with a…

  18. An Inquiry-Based Project Focused on the X-Ray Powder Diffraction Analysis of Common Household Solids

    ERIC Educational Resources Information Center

    Hulien, Molly L.; Lekse, Jonathan W.; Rosmus, Kimberly A.; Devlin, Kasey P.; Glenn, Jennifer R.; Wisneski, Stephen D.; Wildfong, Peter; Lake, Charles H.; MacNeil, Joseph H.; Aitken, Jennifer A.

    2015-01-01

    While X-ray powder diffraction (XRPD) is a fundamental analytical technique used by solid-state laboratories across a breadth of disciplines, it is still underrepresented in most undergraduate curricula. In this work, we incorporate XRPD analysis into an inquiry-based project that requires students to identify the crystalline component(s) of…

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

    PubMed Central

    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. Adsorption of 2-propanol on ice probed by ambient pressure X-ray photoelectron spectroscopy

    DOE PAGES

    Newberg, John T.; Bluhm, Hendrik

    2015-08-18

    The interaction of 2-propanol with ice was examined via ambient pressure X-ray photoelectron spectroscopy (APXPS), a surface sensitive technique that probes the adsorbed 2-propanol directly with submonolayer resolution. Isothermal uptake experiments were performed on vapor deposited ice at 227 K in the presence of the equilibrium water vapor pressure of 0.05 Torr and 2-propanol partial pressures ranging from 5 × 10-5 to 2 × 10-3 Torr. The C 1s APXPS spectra of adsorbed 2-propanol showed two characteristic peaks associated with the COH alcohol group and CMe methyl groups in a 1 : 2 ratio, respectively. Coverage increased with 2-propanol partialmore » pressure and followed first order Langmuir kinetics with a Langmuir constant of K = 6.3 × 103 Torr-1. The 1 : 2 ratio of COH : CMe remained constant with increasing coverage, indicating there is no chemical reaction upon adsorption. The observed Langmuir kinetics using APXPS is consistent with previous observations of other small chain alcohols via indirect adsorption methods using, e.g., Knudsen cell and coated wall flow tube reactors.« less

  1. Adsorption of 2-propanol on ice probed by ambient pressure X-ray photoelectron spectroscopy

    SciTech Connect

    Newberg, John T.; Bluhm, Hendrik

    2015-08-18

    The interaction of 2-propanol with ice was examined via ambient pressure X-ray photoelectron spectroscopy (APXPS), a surface sensitive technique that probes the adsorbed 2-propanol directly with submonolayer resolution. Isothermal uptake experiments were performed on vapor deposited ice at 227 K in the presence of the equilibrium water vapor pressure of 0.05 Torr and 2-propanol partial pressures ranging from 5 × 10-5 to 2 × 10-3 Torr. The C 1s APXPS spectra of adsorbed 2-propanol showed two characteristic peaks associated with the COH alcohol group and CMe methyl groups in a 1 : 2 ratio, respectively. Coverage increased with 2-propanol partial pressure and followed first order Langmuir kinetics with a Langmuir constant of K = 6.3 × 103 Torr-1. The 1 : 2 ratio of COH : CMe remained constant with increasing coverage, indicating there is no chemical reaction upon adsorption. The observed Langmuir kinetics using APXPS is consistent with previous observations of other small chain alcohols via indirect adsorption methods using, e.g., Knudsen cell and coated wall flow tube reactors.

  2. Adsorption of 2-propanol on ice probed by ambient pressure X-ray photoelectron spectroscopy.

    PubMed

    Newberg, John T; Bluhm, Hendrik

    2015-09-28

    The interaction of 2-propanol with ice was examined via ambient pressure X-ray photoelectron spectroscopy (APXPS), a surface sensitive technique that probes the adsorbed 2-propanol directly with submonolayer resolution. Isothermal uptake experiments were performed on vapor deposited ice at 227 K in the presence of the equilibrium water vapor pressure of 0.05 Torr and 2-propanol partial pressures ranging from 5 × 10(-5) to 2 × 10(-3) Torr. The C 1s APXPS spectra of adsorbed 2-propanol showed two characteristic peaks associated with the COH alcohol group and CMe methyl groups in a 1 : 2 ratio, respectively. Coverage increased with 2-propanol partial pressure and followed first order Langmuir kinetics with a Langmuir constant of K = 6.3 × 10(3) Torr(-1). The 1 : 2 ratio of COH : CMe remained constant with increasing coverage, indicating there is no chemical reaction upon adsorption. The observed Langmuir kinetics using APXPS is consistent with previous observations of other small chain alcohols via indirect adsorption methods using, e.g., Knudsen cell and coated wall flow tube reactors. PMID:26299301

  3. An electrochemical cell for in operando studies of lithium/sodium batteries using a conventional x-ray powder diffractometer

    SciTech Connect

    Shen, Yanbin; Pedersen, Erik E.; Christensen, Mogens; Iversen, Bo B.

    2014-10-15

    An electrochemical cell has been designed for powder X-ray diffraction studies of lithium ion batteries (LIB) and sodium ion batteries (SIB) in operando with high time resolution using a conventional powder X-ray diffractometer. The cell allows for studies of both anode and cathode electrode materials in reflection mode. The cell design closely mimics that of standard battery testing coin cells and allows obtaining powder X-ray diffraction patterns under representative electrochemical conditions. In addition, the cell uses graphite as the X-ray window instead of beryllium, and it is easy to operate and maintain. Test examples on lithium insertion/extraction in two spinel-type LIB electrode materials (Li{sub 4}Ti{sub 5}O{sub 12} anode and LiMn{sub 2}O{sub 4} cathode) are presented as well as first results on sodium extraction from a layered SIB cathode material (Na{sub 0.84}Fe{sub 0.56}Mn{sub 0.44}O{sub 2})

  4. Quantification of febuxostat polymorphs using powder X-ray diffraction technique.

    PubMed

    Qiu, Jing-bo; Li, Gang; Sheng, Yue; Zhu, Mu-rong

    2015-03-25

    Febuxostat is a pharmaceutical compound with more than 20 polymorphs of which form A is most widely used and usually exists in a mixed polymorphic form with form G. In the present study, a quantification method for polymorphic form A and form G of febuxostat (FEB) has been developed using powder X-ray diffraction (PXRD). Prior to development of a quantification method, pure polymorphic form A and form G are characterized. A continuous scan with a scan rate of 3° min(-1) over an angular range of 3-40° 2θ is applied for the construction of the calibration curve using the characteristic peaks of form A at 12.78° 2θ (I/I0100%) and form G at 11.72° 2θ (I/I0100%). The linear regression analysis data for the calibration plots shows good linear relationship with R(2)=0.9985 with respect to peak area in the concentration range 10-60 wt.%. The method is validated for precision, recovery and ruggedness. The limits of detection and quantitation are 1.5% and 4.6%, respectively. The obtained results prove that the method is repeatable, sensitive and accurate. The proposed developed PXRD method can be applied for the quantitative analysis of mixtures of febuxostat polymorphs (forms A and G).

  5. Versatile in situ powder X-ray diffraction cells for solid–gas investigations

    PubMed Central

    Jensen, Torben R.; Nielsen, Thomas K.; Filinchuk, Yaroslav; Jørgensen, Jens-Erik; Cerenius, Yngve; Gray, Evan MacA.; Webb, Colin J.

    2010-01-01

    This paper describes new sample cells and techniques for in situ powder X-ray diffraction specifically designed for gas absorption studies up to ca 300 bar (1 bar = 100 000 Pa) gas pressure. The cells are for multipurpose use, in particular the study of solid–gas reactions in dosing or flow mode, but can also handle samples involved in solid–liquid–gas studies. The sample can be loaded into a single-crystal sapphire (Al2O3) capillary, or a quartz (SiO2) capillary closed at one end. The advantages of a sapphire single-crystal cell with regard to rapid pressure cycling are discussed, and burst pressures are calculated and measured to be ∼300 bar. An alternative and simpler cell based on a thin-walled silicate or quartz glass capillary, connected to a gas source via a VCR fitting, enables studies up to ∼100 bar. Advantages of the two cell types are compared and their applications are illustrated by case studies. PMID:22477780

  6. Crystal structure of nitarsone determined from synchrotron X-ray powder diffraction data

    NASA Astrophysics Data System (ADS)

    van der Lee, A.; Richez, P.; Tapiero, C.

    2005-05-01

    The crystal structure of nitarsone, 4-nitrophenylarsonic acid, a substitute for nifursol and dimetridazole in the prevention and treatment of turkey histomoniasis desease, has been determined from synchrotron X-ray powder diffraction data. Nitarsone crystallizes in the monoclinic space group P2 1/ n with unit cell parameters a=7.46413(5), b=25.68543(17), c=4.657388(32) Å, β=105.4670(5)°. The structure was solved using simulated annealing techniques by treating the molecule as a rigid body for which the configuration resulting from an energy minimization was used in slightly adapted form. Structure refinement treated the NO 2 and the AsO(OH) 2 groups as free groups, leading to final confidence factors Rp=0.059 and Rwp=0.071. The crystal structure contains 4 molecules per unit cell that are hydrogen bonded to form infinite chains of dimers running along the c-axis. Nitarsone's low toxicity when compared with inorganic sources of arsenic is explained by the existence of a partial double C-As bond (1.866(5) Å) which confers greater stability so that under physiological conditions nitarsone is not converted to mineral-like As V or III.

  7. A wavelet transform algorithm for peak detection and application to powder x-ray diffraction data

    SciTech Connect

    Gregoire, John M.; Dale, Darren; van Dover, R. Bruce

    2011-01-01

    Peak detection is ubiquitous in the analysis of spectral data. While many noise-filtering algorithms and peak identification algorithms have been developed, recent work [P. Du, W. Kibbe, and S. Lin, Bioinformatics 22, 2059 (2006); A. Wee, D. Grayden, Y. Zhu, K. Petkovic-Duran, and D. Smith, Electrophoresis 29, 4215 (2008)] has demonstrated that both of these tasks are efficiently performed through analysis of the wavelet transform of the data. In this paper, we present a wavelet-based peak detection algorithm with user-defined parameters that can be readily applied to the application of any spectral data. Particular attention is given to the algorithm's resolution of overlapping peaks. The algorithm is implemented for the analysis of powder diffraction data, and successful detection of Bragg peaks is demonstrated for both low signal-to-noise data from theta–theta diffraction of nanoparticles and combinatorial x-ray diffraction data from a composition spread thin film. These datasets have different types of background signals which are effectively removed in the wavelet-based method, and the results demonstrate that the algorithm provides a robust method for automated peak detection.

  8. Powder X-ray diffraction can differentiate between enantiomeric variants of calcium lactate pentahydrate crystal in cheese.

    PubMed

    Tansman, G F; Kindstedt, P S; Hughes, J M

    2014-12-01

    Powder X-ray diffraction has been used for decades to identify crystals of calcium lactate pentahydrate in Cheddar cheese. According to this method, diffraction patterns are generated from a powdered sample of the crystals and compared with reference cards within a database that contains the diffraction patterns of known crystals. During a preliminary study of crystals harvested from various Cheddar cheese samples, we observed 2 slightly different but distinct diffraction patterns that suggested that calcium lactate pentahydrate may be present in 2 different crystalline forms. We hypothesized that the 2 diffraction patterns corresponded to 2 enantiomeric forms of calcium lactate pentahydrate (L- and DL-) that are believed to occur in Cheddar cheese, based on previous studies involving enzymatic analyses of the lactate enantiomers in crystals obtained from Cheddar cheeses. However, the powder X-ray diffraction database currently contains only one reference diffraction card under the title “calcium lactate pentahydrate.” To resolve this apparent gap in the powder X-ray diffraction database, we generated diffraction patterns from reagent-grade calcium l-lactate pentahydrate and laboratory-synthesized calcium dl-lactate pentahydrate. From the resulting diffraction patterns we determined that the existing reference diffraction card corresponds to calcium dl-lactate pentahydrate and that the other form of calcium lactate pentahydrate observed in cheese crystals corresponds to calcium l-lactate pentahydrate. Therefore, this report presents detailed data from the 2 diffraction patterns, which may be used to prepare 2 reference diffraction cards that differentiate calcium l-lactate pentahydrate from calcium dl-lactate pentahydrate. Furthermore, we collected crystals from the exteriors and interiors of Cheddar cheeses to demonstrate the ability of powder X-ray diffraction to differentiate between the 2 forms of calcium lactate pentahydrate crystals in Cheddar cheeses

  9. Characterization of phase transitions during freeze-drying by in situ X-ray powder diffractometry.

    PubMed

    Cavatur, R K; Suryanarayanan, R

    1998-11-01

    The purpose of this research was to develop the technique of in situ freeze-drying in the sample chamber of an X-ray powder diffractometer (XRD) and to monitor the phase transitions during the freeze-drying of aqueous solutions of sodium nafcillin (I) and mannitol (II). Aqueous solutions of I and II were frozen under controlled conditions in the sample chamber of an XRD. This variable temperature XRD was modified so that the sample chamber could be evacuated and the samples dried under reduced pressures. Thus the entire freeze-drying cycle was carried out in the XRD holder and the solid-state was monitored during the various stages of the process. Frozen solutions of I when annealed at -4 degrees C, resulted in crystallization of the solute as 'sodium nafcillin hydrate' (unknown stoichiometry). Primary drying at -10 degrees C, resulted in partial dehydration to a poorly crystalline sodium nafcillin hemihydrate. There was no crystallization of mannitol when solutions of II were cooled and subjected to primary drying at -50 degrees C. During the drying, the intensities of the characteristic X-ray lines of ice (d-spacings of 3.94, 3.70 and 3.48 A) were quantified. This enabled real time monitoring of the complete sublimation of crystalline ice. When the secondary drying was carried out at -25 degrees C, mannitol crystallized as an anhydrous mixture of the delta- and beta-polymorphs. In a second set of experiments, the frozen solutions were warmed to -25 degrees C and subjected to primary drying. Mannitol crystallized and its XRD pattern matched that of mannitol hydrate reported recently (Yu et al., Pharm. Res., 14S (1997) S-445). When the secondary drying was carried out at -10 degrees C, there was no change in the XRD pattern suggesting the formation of a dehydrated hydrate. This in situ XRD technique enabled us to characterize the phase transitions during freeze-drying. It would be useful in developing a mechanistic understanding of the alterations in the solid

  10. Understanding the Adsorption Mechanism of Xe and Kr in a Metal-Organic Framework from X-ray Structural Analysis and First-Principles Calculations.

    PubMed

    Ghose, Sanjit K; Li, Yan; Yakovenko, Andrey; Dooryhee, Eric; Ehm, Lars; Ecker, Lynne E; Dippel, Ann-Christin; Halder, Gregory J; Strachan, Denis M; Thallapally, Praveen K

    2015-05-21

    Enhancement of adsorption capacity and separation of radioactive Xe/Kr at room temperature and above is a challenging problem. Here, we report a detailed structural refinement and analysis of the synchrotron X-ray powder diffraction data of Ni-DODBC metal organic framework with in situ Xe and Kr adsorption at room temperature and above. Our results reveal that Xe and Kr adsorb at the open metal sites, with adsorption geometries well reproduced by DFT calculations. The measured temperature-dependent adsorption capacity of Xe is substantially larger than that for Kr, indicating the selectivity of Xe over Kr and is consistent with the more negative adsorption energy (dominated by van der Waals dispersion interactions) predicted from DFT. Our results reveal critical structural and energetic information about host-guest interactions that dictate the selective adsorption mechanism of these two inert gases, providing guidance for the design and synthesis of new MOF materials for the separation of environmentally hazardous gases from nuclear reprocessing applications. PMID:26263249

  11. Understanding the Adsorption Mechanism of Xe and Kr in a Metal-Organic Framework from X-ray Structural Analysis and First- Principles Calculations

    SciTech Connect

    Ghose, Sanjit K.; Li, Yan; Yakovenko, Andrey; Dooryhee, Eric; Ehm, Lars; Ecker, Lynne E.; Dippel, Ann-Christin; Halder, Gregory J.; Strachan, Denis M.; Thallapally, Praveen K.

    2015-04-16

    Enhancement of adsorption capacity and separation of radioactive Xe/Kr at room temperature and above is a challenging problem. Here, we report a detailed structural refinement and analysis of the synchrotron X-ray powder diffraction data of Ni-DODBC metal organic framework with in situ Xe and Kr adsorption at room temperature and above. Our results reveal that Xe and Kr adsorb at the open metal sites, with adsorption geometries well reproduced by DFT calculations. The measured temperature-dependent adsorption capacity of Xe is substantially larger than that for Kr, indicating the selectivity of Xe over Kr and is consistent with the more negative adsorption energy (dominated by van der Waals dispersion interactions) predicted from DFT. Our results reveal critical structural and energetic information about host–guest interactions that dictate the selective adsorption mechanism of these two inert gases, providing guidance for the design and synthesis of new MOF materials for the separation of environmentally hazardous gases from nuclear reprocessing applications.

  12. Understanding the Adsorption Mechanism of Xe and Kr in a Metal-Organic Framework from X-ray Structural Analysis and First-Principles Calculations.

    PubMed

    Ghose, Sanjit K; Li, Yan; Yakovenko, Andrey; Dooryhee, Eric; Ehm, Lars; Ecker, Lynne E; Dippel, Ann-Christin; Halder, Gregory J; Strachan, Denis M; Thallapally, Praveen K

    2015-05-21

    Enhancement of adsorption capacity and separation of radioactive Xe/Kr at room temperature and above is a challenging problem. Here, we report a detailed structural refinement and analysis of the synchrotron X-ray powder diffraction data of Ni-DODBC metal organic framework with in situ Xe and Kr adsorption at room temperature and above. Our results reveal that Xe and Kr adsorb at the open metal sites, with adsorption geometries well reproduced by DFT calculations. The measured temperature-dependent adsorption capacity of Xe is substantially larger than that for Kr, indicating the selectivity of Xe over Kr and is consistent with the more negative adsorption energy (dominated by van der Waals dispersion interactions) predicted from DFT. Our results reveal critical structural and energetic information about host-guest interactions that dictate the selective adsorption mechanism of these two inert gases, providing guidance for the design and synthesis of new MOF materials for the separation of environmentally hazardous gases from nuclear reprocessing applications.

  13. Unmixing 40Ar/39Ar Muscovite Ages Using Powder X-ray Diffraction

    NASA Astrophysics Data System (ADS)

    McAleer, R. J.; Kunk, M. J.; Valley, P. M.; Walsh, G. J.; Bish, D. L.; Wintsch, R. P.

    2014-12-01

    Whole rock powder X-ray diffraction (XRD) experiments from eight samples collected across a retrograde ductile shear zone in the Devonian Littleton Formation near Claremont, NH, exhibit broad and asymmetric to bimodal muscovite 00l reflections. These composite 00l reflections exhibit a systematic change in shape with increasing retrograde strain. Microtextural relationships, electron microprobe quantitative analyses, and element mapping indicate that the change in peak shape reflects progressive dissolution of metastable Na-rich muscovite and the precipitation of stable Na-poor muscovite. 40Ar/39Ar step heating experiments on muscovite concentrates from these samples show a decrease in total gas age from 274 to 258 Ma as the highest strain zone is approached, and steps within individual spectra range in age by ~20 m.y. The correlation between age and 00l peak shape suggests that the argon isotopic system also tracks the dissolution-precipitation process. Furthermore, the variation in age during step heating indicates that these populations exhibit different in-vacuo degassing behavior. Comparison of whole rock and muscovite concentrate XRD patterns from the same samples shows that the mineral separation process can fractionate these muscovite populations. With this knowledge, four muscovite concentrates were prepared from a single hand sample, analyzed by XRD, and dated. Combining modal estimates from XRD experiments with total gas ages, the four splits narrowly define a mixing line that resolves end-member ages of 250 and 300 Ma for the neocrystallized and earlier high grade populations of muscovite, respectively. These ages are consistent with age data from all other samples. The results show that, in some settings, powder XRD provides a powerful and time effective method to both identify the existence of and establish the proportions of multiple compositional populations of muscovite prior to 40Ar/39Ar analysis. This approach will be especially useful in

  14. Quantitative determination of mineral composition by powder X-ray diffraction

    DOEpatents

    Pawloski, Gayle A.

    1986-01-01

    An external standard intensity ratio method is used for quantitatively determining mineralogic compositions of samples by x-ray diffraction. The method uses ratios of x-ray intensity peaks from a single run. Constants are previously determined for each mineral which is to be quantitatively measured. Ratios of the highest intensity peak of each mineral to be quantified in the sample and the highest intensity peak of a reference mineral contained in the sample are used to calculate sample composition.

  15. Quantitative determination of mineral composition by powder x-ray diffraction

    DOEpatents

    Pawloski, G.A.

    1984-08-10

    An external standard intensity ratio method is used for quantitatively determining mineralogic compositions of samples by x-ray diffraction. The method uses ratios of x-ray intensity peaks from a single run. Constants are previously determined for each mineral which is to be quantitatively measured. Ratios of the highest intensity peak of each mineral to be quantified in the sample and the highest intensity peak of a reference mineral contained in the sample are used to calculate sample composition.

  16. X-Ray Powder Diffraction Study of Synthetic Palmierite, K{sub 2}Pb(SO{sub 4}){sub 2}

    SciTech Connect

    TISSOT JR.,RALPH G.; RODRIGUEZ,MARK A.; SIPOLA,DIANA L.; VOIGT,JAMES A.

    2000-12-19

    Palmierite (K{sub 2}Pb(SO{sub 4}){sub 2}) has been prepared via a chemical synthesis method. Intensity differences were observed when X-ray powder data from the newly synthesized compound were compared to the published powder diffraction card (PDF) 29-1015 for Palmierite. Investigation of these differences indicated the possibility of preferred orientation and/or chemical inhomogeneity affecting intensities, particularly those of the basal (00{ell}) reflections. Annealing of the Palmierite was found to reduce the effects of preferred orientation. Electron microprobe analysis confirmed K:Pb:S as 2:1:2 for the annealed Palmierite powder. Subsequent least-squares refinement and Rietveld analysis of the annealed powder showed peak intensities very close to that of a calculated Palmierite pattern (based on single crystal data), yet substantially higher than many of the PDF 29-1015 published intensities. Further investigation of peak intensity variation via calculated patterns suggested that the intensity discrepancies between the annealed sample and those found in PDF 29-1015 were potentially due to chemical variation in the K{sub 2}Pb(SO{sub 4}){sub 2} composition. X-ray powder diffraction and crystal data for Palmierite are reported for the annealed sample. Palmierite is Trigonal/Hexagonal with unit cell parameters a = 5.497(1){angstrom}, c = 20.864(2) {angstrom}, space group R-3m (166), and Z = 3.

  17. Crystal Engineering on Industrial Diaryl Pigments Using Lattice Energy Minimizations and X-ray Powder Diffraction

    SciTech Connect

    Schmidt,M.; Dinnebier, R.; Kalkhof, H.

    2007-01-01

    Diaryl azo pigments play an important role as yellow pigments for printing inks, with an annual pigment production of more than 50,000 t. The crystal structures of Pigment Yellow 12 (PY12), Pigment Yellow 13 (PY13), Pigment Yellow 14 (PY14), and Pigment Yellow 83 (PY83) were determined from X-ray powder data using lattice energy minimizations and subsequent Rietveld refinements. Details of the lattice energy minimization procedure and of the development of a torsion potential for the biphenyl fragment are given. The Rietveld refinements were carried out using rigid bodies, or constraints. It was also possible to refine all atomic positions individually without any constraint or restraint, even for PY12 having 44 independent non-hydrogen atoms per asymmetric unit. For PY14 (23 independent non-hydrogen atoms), additionally all atomic isotropic temperature factors could be refined individually. PY12 crystallized in a herringbone arrangement with twisted biaryl fragments. PY13 and PY14 formed a layer structure of planar molecules. PY83 showed a herringbone structure with planar molecules. According to quantum mechanical calculations, the twisting of the biaryl fragment results in a lower color strength of the pigments, whereas changes in the substitution pattern have almost no influence on the color strength of a single molecule. Hence, the experimentally observed lower color strength of PY12 in comparison with that of PY13 and PY83 can be explained as a pure packing effect. Further lattice energy calculations explained that the four investigated pigments crystallize in three different structures because these structures are the energetically most favorable ones for each compound. For example, for PY13, PY14, or PY83, a PY12-analogous crystal structure would lead to considerably poorer lattice energies and lower densities. In contrast, lattice energy calculations revealed that PY12 could adopt a PY13-type structure with only slightly poorer energy. This structure was

  18. Exceptional adsorption-induced cluster and network deformation in the flexible metal-organic framework DUT-8(Ni) observed by in situ X-ray diffraction and EXAFS.

    PubMed

    Bon, Volodymyr; Klein, Nicole; Senkovska, Irena; Heerwig, Andreas; Getzschmann, Jürgen; Wallacher, Dirk; Zizak, Ivo; Brzhezinskaya, Maria; Mueller, Uwe; Kaskel, Stefan

    2015-07-14

    The "gate opening" mechanism in the highly flexible MOF Ni2(2,6-ndc)2dabco (DUT-8(Ni), DUT = Dresden University of Technology) with unprecedented unit cell volume change was elucidated in detail using combined single crystal X-ray diffraction, in situ XRD and EXAFS techniques. The analysis of the crystal structures of closed pore (cp) and large pore (lp) phases reveals a drastic and unique unit cell volume expansion of up to 254%, caused by adsorption of gases, surpassing other gas-pressure switchable MOFs significantly. To a certain extent, the structural deformation is specific for the guest molecule triggering the transformation due to subtle differences in adsorption enthalpy, shape, and kinetic diameter of the guest. Combined adsorption and powder diffraction experiments using nitrogen (77 K), carbon dioxide (195 K), and n-butane (272.5 K) as a probe molecules reveal a one-step structural transformation from cp to lp. In contrast, adsorption of ethane (185 K) or ethylene (169 K) results in a two-step transformation with the formation of intermediate phases. In situ EXAFS during nitrogen adsorption was used for the first time to monitor the local coordination geometry of the metal atoms during the structural transformation in flexible MOFs revealing a unique local deformation of the nickel-based paddle-wheel node. PMID:26079102

  19. In situ X-ray powder diffraction, synthesis, and magnetic properties of InVO{sub 3}

    SciTech Connect

    Lundgren, Rylan J.; Cranswick, Lachlan M.D.; Bieringer, Mario . E-mail: Mario_Bieringer@umanitoba.ca

    2006-12-15

    We report the first synthesis and high-temperature in situ X-ray diffraction study of InVO{sub 3}. Polycrystalline InVO{sub 3} has been prepared via reduction of InVO{sub 4} using a carbon monoxide/carbon dioxide buffer gas. InVO{sub 3} crystallizes in the bixbyite structure in space group Ia-3 (206) with a=9.80636(31) A with In{sup 3+}/V{sup 3+} disorder on the (8b) and (24d) cation sites. In situ powder X-ray diffraction experiments and thermal gravimetric analysis in a CO/CO{sub 2} buffer gas revealed the existence of the metastable phase InVO{sub 3}. Bulk samples with 98.5(2)% purity were prepared using low-temperature reduction methods. The preparative methods limited the crystallinity of this new phase to approximately 225(50) A. Magnetic susceptibility and neutron diffraction experiments suggest a spin-glass ground state for InVO{sub 3}. - Graphical abstract: In situ powder X-ray diffractograms for the reduction of InVO{sub 4} in CO/CO{sub 2}. The three temperature regions show the conversion of InVO{sub 4} to InVO{sub 3} and final decomposition into In{sub 2}O{sub 3} and V{sub 2}O{sub 3}.

  20. A pH-dependent x-ray absorption spectroscopy study of U adsorption to bacterial cell walls.

    SciTech Connect

    Ravel, B.; Kelly, S. D.; Gorman-Lewis, D.; Boyanov, M. I.; Fein, J. B.; Kemner, K. M.; Biosciences Division; Univ. of Notre Dame

    2006-01-01

    Metal mobility in subsurface water systems involves the complex interaction of the metal, the fluid, and the mineral surfaces over which the fluid flows. This mobility is further influenced by metal adsorption onto bacteria and other biomass in the subsurface. To better understand the mechanism of this adsorption as well as its dependence on the chemical composition of the fluid, we have performed a series of metal adsorption experiments of aqueous uranyl (UO{sub 2}){sup 2+} to the gram-positive bacterium B. subtilis in the presence and absence of carbonate along with X-ray Absorption Spectroscopy (XAS) to determine the binding structures at the cell surface. In this paper we demonstrate an approach to the XAS data analysis which allows us to measure the partitioning of the adsorption of uranium to hydroxyl, carboxyl/carbonato, and phosphoryl active sites at the cell surface.

  1. Adsorption of Uranyl ions on Amine-functionalization of MIL-101(Cr) Nanoparticles by a Facile Coordination-based Post-synthetic strategy and X-ray Absorption Spectroscopy Studies

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Yong; Zhang, Na; Zhang, Linjuan; Fang, Yongzheng; Deng, Wei; Yu, Ming; Wang, Ziqiang; Li, Lina; Liu, Xiyan; Li, Jingye

    2015-09-01

    By a facile coordination-based post-synthetic strategy, the high surface area MIL-101(Cr) nanoparticles was functionallized by grafting amine group of ethylenediamine (ED) on coordinatively unsaturated Cr(III) centers, yielding a series of ED-MIL-101(Cr)-based adsorbents and their application for adsorption of U(VI) from aqueous solution were also studied. The obtained ED-functionallized samples with different ED contents were characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), FTIR, elemental analysis (EA) and N2 adsorption and desorption isothermal. Compared with the pristine MIL-101(Cr) sorbents, the ED-functionallized MIL-101(Cr) exhibits significantly higher adsorption capacity for U(VI) ions from water with maximum adsorption capacities as high as 200 mg/g (corresponding to 100% extraction rate) at pH of 4.5 with ED/Cr ratio of 0.68 and the sorbed U(VI) ions can easily be desorbed at lower pH (pH ≤ 2.0). The adsorption mode of U(VI) ions and effects of grafted ED on the MIL-101(Cr) frameworks were also been studied by X-ray absorption spectroscopy (XAS). We believe that this work establishes a simple and energy efficient route to a novel type of functional materials for U(VI) ions extraction from solution via the post-synthetic modification (PSM) strategy.

  2. Adsorption of Uranyl ions on Amine-functionalization of MIL-101(Cr) Nanoparticles by a Facile Coordination-based Post-synthetic strategy and X-ray Absorption Spectroscopy Studies

    PubMed Central

    Zhang, Jian-Yong; Zhang, Na; Zhang, Linjuan; Fang, Yongzheng; Deng, Wei; Yu, Ming; Wang, Ziqiang; Li, Lina; Liu, Xiyan; Li, Jingye

    2015-01-01

    By a facile coordination-based post-synthetic strategy, the high surface area MIL-101(Cr) nanoparticles was functionallized by grafting amine group of ethylenediamine (ED) on coordinatively unsaturated Cr(III) centers, yielding a series of ED-MIL-101(Cr)-based adsorbents and their application for adsorption of U(VI) from aqueous solution were also studied. The obtained ED-functionallized samples with different ED contents were characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), FTIR, elemental analysis (EA) and N2 adsorption and desorption isothermal. Compared with the pristine MIL-101(Cr) sorbents, the ED-functionallized MIL-101(Cr) exhibits significantly higher adsorption capacity for U(VI) ions from water with maximum adsorption capacities as high as 200 mg/g (corresponding to 100% extraction rate) at pH of 4.5 with ED/Cr ratio of 0.68 and the sorbed U(VI) ions can easily be desorbed at lower pH (pH ≤ 2.0). The adsorption mode of U(VI) ions and effects of grafted ED on the MIL-101(Cr) frameworks were also been studied by X-ray absorption spectroscopy (XAS). We believe that this work establishes a simple and energy efficient route to a novel type of functional materials for U(VI) ions extraction from solution via the post-synthetic modification (PSM) strategy. PMID:26354407

  3. Adsorption of Uranyl ions on Amine-functionalization of MIL-101(Cr) Nanoparticles by a Facile Coordination-based Post-synthetic strategy and X-ray Absorption Spectroscopy Studies.

    PubMed

    Zhang, Jian-Yong; Zhang, Na; Zhang, Linjuan; Fang, Yongzheng; Deng, Wei; Yu, Ming; Wang, Ziqiang; Li, Lina; Liu, Xiyan; Li, Jingye

    2015-09-10

    By a facile coordination-based post-synthetic strategy, the high surface area MIL-101(Cr) nanoparticles was functionallized by grafting amine group of ethylenediamine (ED) on coordinatively unsaturated Cr(III) centers, yielding a series of ED-MIL-101(Cr)-based adsorbents and their application for adsorption of U(VI) from aqueous solution were also studied. The obtained ED-functionallized samples with different ED contents were characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), FTIR, elemental analysis (EA) and N2 adsorption and desorption isothermal. Compared with the pristine MIL-101(Cr) sorbents, the ED-functionallized MIL-101(Cr) exhibits significantly higher adsorption capacity for U(VI) ions from water with maximum adsorption capacities as high as 200 mg/g (corresponding to 100% extraction rate) at pH of 4.5 with ED/Cr ratio of 0.68 and the sorbed U(VI) ions can easily be desorbed at lower pH (pH ≤ 2.0). The adsorption mode of U(VI) ions and effects of grafted ED on the MIL-101(Cr) frameworks were also been studied by X-ray absorption spectroscopy (XAS). We believe that this work establishes a simple and energy efficient route to a novel type of functional materials for U(VI) ions extraction from solution via the post-synthetic modification (PSM) strategy.

  4. Crystal structure of anhydrous tripotassium citrate from laboratory X-ray powder diffraction data and DFT comparison.

    PubMed

    Rammohan, Alagappa; Kaduk, James A

    2016-08-01

    The crystal structure of anhydrous tripotassium citrate, [K3(C6H5O7)] n , has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The three unique potassium cations are 6-, 8-, and 6-coordinate (all irregular). The [KO n ] coordination polyhedra share edges and corners to form a three-dimensional framework, with channels running parallel to the c axis. The only hydrogen bond is an intra-molecular one involving the hy-droxy group and the central carboxyl-ate group, with graph-set motif S(5). PMID:27536403

  5. Crystal structure of anhydrous tripotassium citrate from laboratory X-ray powder diffraction data and DFT comparison

    PubMed Central

    Rammohan, Alagappa; Kaduk, James A.

    2016-01-01

    The crystal structure of anhydrous tripotassium citrate, [K3(C6H5O7)]n, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The three unique potassium cations are 6-, 8-, and 6-coordinate (all irregular). The [KOn] coordination polyhedra share edges and corners to form a three-dimensional framework, with channels running parallel to the c axis. The only hydrogen bond is an intra­molecular one involving the hy­droxy group and the central carboxyl­ate group, with graph-set motif S(5). PMID:27536403

  6. Effect of powder sample granularity on fluorescent intensity and on thermal parameters in x-ray diffraction Rietveld analysis

    SciTech Connect

    Sparks, C.J.; Specht, E.D.; Ice, G.E. ); Kumar, R.; Zschack, P. ); Shiraishi, T. ); Hisatsune, K. )

    1991-01-01

    The effect of sample granularity on diffracted x-ray intensity was evaluated by measuring the 2{theta} dependence of x-ray fluorescence from various samples. Measurements were made in the symmetric geometry on samples ranging from single crystals to highly absorbing coarse powders. A characteristic shape for the absorption correction was observed. A demonstration of the sensitivity of Rietveld refined site occupation parameters is made on CuAu and Cu{sub 50}Au{sub 44}Ni{sub 6} alloys refined with and without granularity corrections. These alloys provide a good example of the effect of granularity due to their large linear x-ray absorption coefficients. Sample granularity and refined thermal parameters obtained from the Rietveld analysis were found to be correlated. Without a granularity correction, the refined thermal parameters are too low and can actually become negative in an attempt to compensate for granularity. A general shape for granularity correction can be included in refinement procedures. If no granularity correction is included, data should be restricted to above 30{degrees} 2{theta}, and thermal parameters should be ignored unless extreme precautions are taken to produce >5 {mu}m particles and high packing densities.

  7. From particle to powder properties - A mesoscopic approach combining micro-scale experiments and X-ray microtomography

    NASA Astrophysics Data System (ADS)

    Strege, S.; Zetzener, H.; Kwade, A.

    2013-06-01

    The detailed understanding of particle flow is of special interest from the academic point of view and crucial for a safe and reliable process design. Due to poor flowability and heterogeneous bulk structures, the handling of fine and cohesive powders is particularly challenging. Recently, high resolution X-ray microtomography (XMT) has proved to be a reliable tool for analysing powder structures on bulk and particle level. This study now presents a complementary approach of micro-scale experiments and XMT analysis to improve the general understanding of particle flow. Centrepiece of the experimental investigation is a novel micro shear tester (μST) for very small powder samples (volumes from 0.005 to 0.1 mL), which has been integrated into a high resolution XMT system. By combining μST and XMT it is possible to extract detailed 3D images of precisely compacted and sheared powder samples. A SiO2 powder consisting of spherical, adhesive particles (x50,3 ≈ 11,2 μm) and a limestone powder consisting of irregular shaped particles (x50,3 ≈ 4,8 μm) are scanned before and after various shear and compaction tests. A detailed analysis of the sample microstructure reveals important information on the particle network and the bulk structure. The impact of the test procedure on mesoscopic heterogeneities and shear zones inside the sample is discussed. Moreover, the measurement of yield loci in the novel μST is presented.

  8. Formation mechanism of LiFePO 4/C composite powders investigated by X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hsu, Kuei-Feng; Hu, Shao-Kang; Chen, Chinh-Hsiang; Cheng, Ming-Yao; Tsay, Sun-Yuan; Chou, Tse-Chuan; Sheu, Hwo-Shuenn; Lee, Jyh-Fu; Hwang, Bing-Joe

    The local structure and oxidation states for both the precursors and the LiFePO 4/C composite powders were investigated by X-ray absorption spectroscopy (XAS) to provide a deep insight into their formation mechanism. It was found that the local structure and oxidation states of the precursors and the synthesized LiFePO 4/C powders as well as the electrochemical properties of the synthesized powders were strongly influenced by the R ratio (R: molar ratio of citric acid to total metal ions). The oxidation states of iron ions of the precursors for R = 1 and 0.75 consist mainly of Fe(II) and traces of Fe(III). However, the oxidation state of iron ions of the precursor for R = 0.5 comprises mainly of Fe(III). The oxidation state of iron ions of all the synthesized powders is Fe(II). The structure of the precursors and the synthesized powders for R = 1 and 0.75 is more ordering than that for R = 0.5. It is in good agreement with the observation of the cation mixing obtained from the Riteveld analysis of the XRD data. The better the electrochemical performance is, the more ordering the structure or the less the cation mixing. However, the effect of the R values on the carbon content is also essential for the electrochemical properties of the synthesized LiFePO 4/C composite powders. Increasing the carbon content leads to the increase in the electronic conductivity but impedes the Li + ion diffusion of the composite materials. Consequently, the powders synthesized at the optimal R ratio of 0.75 exhibited the highest initial capacity, about 150 mAh g -1 when cycled at 1/40 C rate at room temperature. The structural scheme of the precursors and the synthesized powders and the formation mechanism of the LiFePO 4/C composite powders are also addressed in this work.

  9. Azine bridged silver coordination polymers: Powder X-ray diffraction route to crystal structure determination of silver benzotriazole

    SciTech Connect

    Rajeswaran, Manju . E-mail: manju.rajeswaran@kodak.com; Blanton, Thomas N.; Giesen, David J.; Whitcomb, David R.; Zumbulyadis, Nicholas; Antalek, Brian J.; Neumann, Marcus M.; Misture, Scott T.

    2006-04-15

    In continuation of our interest in solid-state structures of silver complexes of photographic importance, the structure for silver benzotriazole (AgBZT), has now been obtained. The preferred method for solving crystal structures is via single-crystal X-ray diffraction (XRD). However, for some materials, growing single crystals of appropriate size and quality is often difficult or even impossible. AgBZT is an example of such a silver complex with poor solubility. The usual routes to preparing single crystals using recrystallization from a cooperating solvent resulted in polycrystalline powder samples. We propose a crystal structure for AgBZT, solved from synchrotron X-ray powder diffraction data, using a direct-space Monte Carlo simulated annealing approach. AgBZT crystals are monoclinic (P2{sub 1} /c), with unit cell dimensions, a=14.8052(3) A, b=3.7498(4) A, c=12.3495(12) A, and {beta}=114.200(6){sup o}. The AgBZT complex is constructed from all three of the Benzotriazole (BZT) nitrogens bonding to a separate silver atom. As a consequence of this bonding mode, the structure is a highly cross-linked, coordination polymer.

  10. X-ray powder diffraction study of some dopant positions in unit cells of chosen AIIBVI compounds crystals

    NASA Astrophysics Data System (ADS)

    Michalski, E.; Demianiuk, Mieczyslaw

    1995-10-01

    The characteristic changes in relative reflections intensity (without substantial change of their positions and without any additional reflexes from any new phases) on x-ray powder diffraction patterns from different doped AIIBVI compound crystals have been experimentally registered. On the basis of the powder diffraction data the changes in the lattice constants (increasing as well as decreasing) have been confirmed too. These changes have been tried to be connected with crystal structure under the assumption of statistical occupation of parts of positions chosen from positions possible to occupy in the lattice. The qualitative conformity of calculated relative intensity of x-ray reflections for the best matched models with obtained experimentally and also qualitative conformity of changes in lattice constants have been obtained for examined cases. Simultaneously the possibility of obtaining such conformity for other models (with dopants occupying other positions in lattice) have been excluded. It allows us to determine the position occupying by dopants and to estimate the relative contents of dopants.

  11. Diaplectic Glass Content in Experimentally Shock-loaded Quartz Determined by X-Ray Powder Diffraction

    NASA Technical Reports Server (NTRS)

    Skala, R.; Hoerz, F.; Langenhorst, F.

    2003-01-01

    Quartz is the most common mineral of terrestrial crustal rocks and thus a widespread indicator for impact cratering and associated shock metamorphism. Planar deformation features (PDFs) are among the most prominent and diagnostic shock features in quartz and they represent thin lamellae of glass that formed via solid-state transformations. This socalled 'diaplectic' glass becomes pervasive at higher pressures and results in optically isotropic and X-ray-amorphous phases that resemble texturally the original quartz grains (without evidence of melt flow). In the past, it has been shown that the amount of this amorphous material in experimentally shock-loaded quartz correlates with peak shock pressure. Both reports derive the glass content from density measurements of individual crystals employing the equation X(%) = (rho(sub x) - rho(sub 0))/(rho(sub x) - rho(sub gl)), where x and 0 stands for X-ray and average (optical) density, respectively. The density of glass, rho(sub gl), was adopted as 2.2 g/cu cm. Though the same procedures had been applied, the resulting glass content differs significantly among the above studies. In the present study, we are using a new approach based solely on the integral intensity of a single, carefully selected reflection in the XRD pattern, and we will compare our data to those reported in the literature.

  12. A comparison between different X-ray diffraction line broadening analysis methods for nanocrystalline ball-milled FCC powders

    NASA Astrophysics Data System (ADS)

    Soleimanian, V.; Mojtahedi, M.

    2015-06-01

    The microstructural characteristics of aluminum, copper and nickel powders are investigated using different X-ray diffraction line broadening analysis approaches. Prior to analysis, the powders were ball-milled to produce a nanocrystalline structure with high density of probable types of lattice defects. A variety of methods, including Scherrer, Williamson-Smallman, Williamson-Hall, Warren-Averbach, modified Williamson-Hall, modified Warren-Averbach, Rietveld refinement and whole powder pattern modeling (WPPM) approaches are applied. In this way, microstructural characteristics such as crystallite size, microstrain, dislocation density, effective outer cut-off radius of dislocations and the probability of twining and stacking faults are calculated. On the other hand, the results of conventional and advanced line broadening analysis methods are compared. It is revealed that the density of linear and planar defects in the mechanically deformed aluminum powder is significantly smaller than that of copper and nickel, as well as the level of anisotropic strain broadening. Moreover, the WPPM procedure provided a better profile fitting with more accurate results.

  13. Effect of Stacking Faults on the X-Ray Diffraction Profiles of Beta-SiC Powders

    NASA Technical Reports Server (NTRS)

    Pujar, Vijay V.; Cawley, James D.; Levine, Stanley R. (Technical Monitor)

    1995-01-01

    X-ray diffraction patterns or beta-SiC (3C or the cubic polytype or sic) powders often exhibit an additional peak at d = 0.266 nm, high background intensity around the (111) peak, and relative intensities for peaks which differ from those predicted from the crystal structure. Computer simulations were used to show that all these features are due to stacking faults in the powders and not due to the presence of other polytypes in the powders. Such simulations allow diffraction patterns to be generated for different types, frequencies, and spatial distribution or faults. Comparison of the simulation results to the XRD data indicates that the B-SiC particles consist either of heavily faulted clusters distributed irregularly between regions that have only occasional faults or twins, or the powders consist of two types of particles with different populations of faults: those with a high density of faults and those with only twins or occasional faults. Additional information is necessary to determine which description is correct. However, the simulation results can be used to rule out certain fault configurations.

  14. X-Ray Diffraction.

    ERIC Educational Resources Information Center

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  15. Observation of localized heating phenomena during microwave heating of mixed powders using in situ x-ray diffraction technique

    NASA Astrophysics Data System (ADS)

    Sabelström, N.; Hayashi, M.; Watanabe, T.; Nagata, K.

    2014-10-01

    In materials processing research using microwave heating, there have been several observations of various phenomena occurring known as microwave effects. One significant example of such a phenomenon is increased reaction kinetics. It is believed that there is a possibility that this might be caused by localized heating, were some reactants would attain a higher than apparent temperature. To examine whether such thermal gradients are indeed possible, mixed powders of two microwave non-absorbers, alumina and magnesia, were mixed with graphite, a known absorber, and heated in a microwave furnace. During microwave irradiation, the local temperatures of the respective sample constituents were measured using an in situ x-ray diffraction technique. In the case of the alumina and graphite sample, a temperature difference of around 100 °C could be observed.

  16. High-temperature dehydration of talc: a kinetics study using in situ X-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Wang, Duojun; Yi, Li; Huang, Bojin; Liu, Chuanjiang

    2015-06-01

    High-temperature in situ X-ray powder diffraction patterns were used to study the dehydration kinetics of natural talc with a size of 10-15 µm. The talc was annealed from 1073 to 1223 K, and the variations in the characteristic peaks corresponding to talc with the time were recorded to determine the reaction progress. The decomposition of talc occurred, and peaks corresponding to talc and peaks corresponding to enstatite and quartz were observed. The enstatite and talc exhibited a topotactic relationship. The dehydration kinetics of talc was studied as a function of temperature between 1073 and 1223 K. The kinetics data could be modeled using an Avrami equation that considers nucleation and growth processes ? where n varies from 0.4 to 0.8. The rate constant (k) equation for the natural talc is ? The reaction mechanism for the dehydration of talc is a heterogeneous nucleation and growth mechanism.

  17. Structure of Zr 2(WO 4)(PO 4) 2 from Powder X-Ray Data: Cation Ordering with No Superstructure

    NASA Astrophysics Data System (ADS)

    Evans, J. S. O.; Mary, T. A.; Sleight, A. W.

    1995-11-01

    Department of Chemistry and Center for Advanced Materials Research, Oregon State University, Corvallis, Oregon The ab initio structure determination of Zr2(WO4)(PO4)2 from room temperature powder X-ray diffraction data is reported. This compound crystallizes in the orthorhombic space group Pnca with a = 9.35451(9), b = 12.31831(9), and c = 9.16711(8) Å. The structure is based on ZrO6 octahedra sharing corners with WO4 and PO4 tetrahedra. Although Zr2(WO4)(PO4)2 is isostructural with Fe2(MoO4)3 and its WO4 and PO4 tetrahedra are well ordered, no superstructure or change in space group is required to account for this ordering.

  18. Observation of localized heating phenomena during microwave heating of mixed powders using in situ x-ray diffraction technique

    SciTech Connect

    Sabelström, N. Hayashi, M.; Watanabe, T.; Nagata, K.

    2014-10-28

    In materials processing research using microwave heating, there have been several observations of various phenomena occurring known as microwave effects. One significant example of such a phenomenon is increased reaction kinetics. It is believed that there is a possibility that this might be caused by localized heating, were some reactants would attain a higher than apparent temperature. To examine whether such thermal gradients are indeed possible, mixed powders of two microwave non-absorbers, alumina and magnesia, were mixed with graphite, a known absorber, and heated in a microwave furnace. During microwave irradiation, the local temperatures of the respective sample constituents were measured using an in situ x-ray diffraction technique. In the case of the alumina and graphite sample, a temperature difference of around 100 °C could be observed.

  19. An Implementation of the Fundamental Parameters Approach for Analysis of X-ray Powder Diffraction Line Profiles

    PubMed Central

    Mendenhall, Marcus H.; Mullen, Katharine; Cline, James P.

    2015-01-01

    This work presents an open implementation of the Fundamental Parameters Approach (FPA) models for analysis of X-ray powder diffraction line profiles. The original literature describing these models was examined and code was developed to allow for their use within a Python based least squares refinement algorithm. The NIST interest in the FPA method is specific to its ability to account for the optical aberrations of the powder diffraction experiment allowing for an accurate assessment of lattice parameter values. Lattice parameters are one of the primary certified measurands of NIST Standard Reference Materials (SRMs) for powder diffraction. Lattice parameter values obtained from analysis of data from SRMs 640e and 660c using both the NIST FPA Python code and the proprietary, commercial code Topas, that constitutes the only other actively supported, complete implementation of FPA models within a least-squares data analysis environment, agreed to within 2 fm. This level of agreement demonstrates that both the NIST code and Topas constitute an accurate implementation of published FPA models. PMID:26958448

  20. Solid state characterization and crystal structure from X-ray powder diffraction of two polymorphic forms of ranitidine base.

    PubMed

    de Armas, Héctor Novoa; Peeters, Oswald M; Blaton, Norbert; Van Gyseghem, Elke; Martens, Johan; Van Haele, Gerrit; Van Den Mooter, Guy

    2009-01-01

    Ranitidine hydrochloride (RAN-HCl), a known anti-ulcer drug, is the product of reaction between HCl and ranitidine base (RAN-B). RAN-HCl has been extensively studied; however this is not the case of the RAN-B. The solid state characterization of RAN-B polymorphs has been carried out using different analytical techniques (microscopy, thermal analysis, Fourier transform infrared spectrometry in the attenuated total reflection mode, (13)C-CPMAS-NMR spectroscopy and X-ray powder diffraction). The crystal structures of RAN-B form I and form II have been determined using conventional X-ray powder diffraction in combination with simulated annealing and whole profile pattern matching, and refined using rigid-body Rietveld refinement. RAN-B form I is a monoclinic polymorph with cell parameters: a = 7.317(2), b = 9.021(2), c = 25.098(6) A, beta = 95.690(1) degrees and space group P2(1)/c. The form II is orthorhombic: a = 31.252(4), b = 13.052(2), c = 8.0892(11) A with space group Pbca. In RAN-B polymorphs, the nitro group is involved in a strong intramolecular hydrogen bond responsible for the existence of a Z configuration in the enamine portion of the molecules. A tail to tail packing motif can be denoted via intermolecular hydrogen bonds. The crystal structures of RAN-B forms are compared to those of RAN-HCl polymorphs. RAN-B polymorphs are monotropic polymorphic pairs.

  1. An X-ray absorption study of synthesis- and As adsorption-induced microstructural modifications in Fe oxy-hydroxides.

    PubMed

    Pinakidou, F; Katsikini, M; Simeonidis, K; Paloura, E C; Mitrakas, M

    2015-11-15

    Synthetic adsorbents based on Fe oxy-hydroxides (FeOOH) prepared under a wide range of pH-values via intense oxidation conditions of FeSO4 as well as the As(III) and As(V) adsorption mechanism are investigated using X-ray absorption fine structure (XAFS) spectroscopies at the Fe- and As-K-edges. Synthesis in an alkaline environment promotes the face-connectivity of the Fe(O,OH)6 chains at the expense of edge- and corner-sharing linkage, which is consistent with the lower surface charge density and in turn with the lower arsenic adsorption capacity. Microstructural changes are also detected after As(V) adsorption onto FeOOH synthesized at pH 5.5: the ratio of face-/edge-sharing sites increases from approximately 0.4-0.7 as a function of the As(V)-loading. This modification of the polymeric Fe(O,OH)6 structure at higher As/Fe ratios is attributed to strong As(V) bidentate mononuclear ((2)E) and binuclear ((2)C) adsorption. In contrast, no alterations in the FeOOH microstructure were observed, possibly due to the weaker (2)E linkage of As(III). PMID:26057444

  2. Three-dimensional electron diffraction as a complementary technique to powder X-ray diffraction for phase identification and structure solution of powders.

    PubMed

    Yun, Yifeng; Zou, Xiaodong; Hovmöller, Sven; Wan, Wei

    2015-03-01

    Phase identification and structure determination are important and widely used techniques in chemistry, physics and materials science. Recently, two methods for automated three-dimensional electron diffraction (ED) data collection, namely automated diffraction tomography (ADT) and rotation electron diffraction (RED), have been developed. Compared with X-ray diffraction (XRD) and two-dimensional zonal ED, three-dimensional ED methods have many advantages in identifying phases and determining unknown structures. Almost complete three-dimensional ED data can be collected using the ADT and RED methods. Since each ED pattern is usually measured off the zone axes by three-dimensional ED methods, dynamic effects are much reduced compared with zonal ED patterns. Data collection is easy and fast, and can start at any arbitrary orientation of the crystal, which facilitates automation. Three-dimensional ED is a powerful technique for structure identification and structure solution from individual nano- or micron-sized particles, while powder X-ray diffraction (PXRD) provides information from all phases present in a sample. ED suffers from dynamic scattering, while PXRD data are kinematic. Three-dimensional ED methods and PXRD are complementary and their combinations are promising for studying multiphase samples and complicated crystal structures. Here, two three-dimensional ED methods, ADT and RED, are described. Examples are given of combinations of three-dimensional ED methods and PXRD for phase identification and structure determination over a large number of different materials, from Ni-Se-O-Cl crystals, zeolites, germanates, metal-organic frameworks and organic compounds to intermetallics with modulated structures. It is shown that three-dimensional ED is now as feasible as X-ray diffraction for phase identification and structure solution, but still needs further development in order to be as accurate as X-ray diffraction. It is expected that three-dimensional ED methods

  3. Rb+ adsorption at the quartz(101)-aqueous interface: comparison of resonant anomalous x-ray reflectivity with ab initio calculations

    DOE PAGES

    Bellucci, Francesco; Lee, Sang Soo; Kubicki, James D.; Bandura, Andrei V.; Zhang, Zhan; Wesolowski, David J.; Fenter, Paul

    2015-01-29

    We study adsorption of Rb+ to the quartz(101)–aqueous interface at room temperature with specular X-ray reflectivity, resonant anomalous X-ray reflectivity, and density functional theory. The interfacial water structures observed in deionized water and 10 mM RbCl solution at pH 9.8 were similar, having a first water layer at height of 1.7 ± 0.1 Å above the quartz surface and a second layer at 4.8 ± 0.1 Å and 3.9 ± 0.8 Å for the water and RbCl solutions, respectively. The adsorbed Rb+ distribution is broad and consists of presumed inner-sphere (IS) and outer-sphere (OS) complexes at heights of 1.8 ±more » 0.1 and 6.4 ± 1.0 Å, respectively. Projector-augmented planewave density functional theory (DFT) calculations of potential configurations for neutral and negatively charged quartz(101) surfaces at pH 7 and 12, respectively, reveal a water structure in agreement with experimental results. These DFT calculations also show differences in adsorbed speciation of Rb+ between these two conditions. At pH 7, the lowest energy structure shows that Rb+ adsorbs dominantly as an IS complex, whereas at pH 12 IS and OS complexes have equivalent energies. The DFT results at pH 12 are generally consistent with the two site Rb distribution observed from the X-ray data at pH 9.8, albeit with some differences that are discussed. In conclusion, surface charge estimated on the basis of the measured total Rb+ coverage was -0.11 C/m2, in good agreement with the range of the surface charge magnitudes reported in the literature.« less

  4. An in situ sample environment reaction cell for spatially resolved x-ray absorption spectroscopy studies of powders and small structured reactors

    SciTech Connect

    Zhang, Chu; Gustafson, Johan; Merte, Lindsay R.; Evertsson, Jonas; Norén, Katarina; Carlson, Stefan; Svensson, Håkan; Carlsson, Per-Anders

    2015-03-15

    An easy-to-use sample environment reaction cell for X-ray based in situ studies of powders and small structured samples, e.g., powder, pellet, and monolith catalysts, is described. The design of the cell allows for flexible use of appropriate X-ray transparent windows, shielding the sample from ambient conditions, such that incident X-ray energies as low as 3 keV can be used. Thus, in situ X-ray absorption spectroscopy (XAS) measurements in either transmission or fluorescence mode are facilitated. Total gas flows up to about 500 ml{sub n}/min can be fed while the sample temperature is accurately controlled (at least) in the range of 25–500 °C. The gas feed is composed by a versatile gas-mixing system and the effluent gas flow composition is monitored with mass spectrometry (MS). These systems are described briefly. Results from simultaneous XAS/MS measurements during oxidation of carbon monoxide over a 4% Pt/Al{sub 2}O{sub 3} powder catalyst are used to illustrate the system performance in terms of transmission XAS. Also, 2.2% Pd/Al{sub 2}O{sub 3} and 2% Ag − Al{sub 2}O{sub 3} powder catalysts have been used to demonstrate X-ray absorption near-edge structure (XANES) spectroscopy in fluorescence mode. Further, a 2% Pt/Al{sub 2}O{sub 3} monolith catalyst was used ex situ for transmission XANES. The reaction cell opens for facile studies of structure-function relationships for model as well as realistic catalysts both in the form of powders, small pellets, and coated or extruded monoliths at near realistic conditions. The applicability of the cell for X-ray diffraction measurements is discussed.

  5. An in situ sample environment reaction cell for spatially resolved x-ray absorption spectroscopy studies of powders and small structured reactors

    NASA Astrophysics Data System (ADS)

    Zhang, Chu; Gustafson, Johan; Merte, Lindsay R.; Evertsson, Jonas; Norén, Katarina; Carlson, Stefan; Svensson, Hâkan; Carlsson, Per-Anders

    2015-03-01

    An easy-to-use sample environment reaction cell for X-ray based in situ studies of powders and small structured samples, e.g., powder, pellet, and monolith catalysts, is described. The design of the cell allows for flexible use of appropriate X-ray transparent windows, shielding the sample from ambient conditions, such that incident X-ray energies as low as 3 keV can be used. Thus, in situ X-ray absorption spectroscopy (XAS) measurements in either transmission or fluorescence mode are facilitated. Total gas flows up to about 500 mln/min can be fed while the sample temperature is accurately controlled (at least) in the range of 25-500 °C. The gas feed is composed by a versatile gas-mixing system and the effluent gas flow composition is monitored with mass spectrometry (MS). These systems are described briefly. Results from simultaneous XAS/MS measurements during oxidation of carbon monoxide over a 4% Pt/Al2O3 powder catalyst are used to illustrate the system performance in terms of transmission XAS. Also, 2.2% Pd/Al2O3 and 2% Ag - Al2O3 powder catalysts have been used to demonstrate X-ray absorption near-edge structure (XANES) spectroscopy in fluorescence mode. Further, a 2% Pt/Al2O3 monolith catalyst was used ex situ for transmission XANES. The reaction cell opens for facile studies of structure-function relationships for model as well as realistic catalysts both in the form of powders, small pellets, and coated or extruded monoliths at near realistic conditions. The applicability of the cell for X-ray diffraction measurements is discussed.

  6. Assessment of the Stoichiometry of Multicomponent Crystals Using Only X-ray Powder Diffraction Data.

    PubMed

    Maguire, Courtney K; Brunskill, Andrew P J

    2015-06-01

    Knowledge of the unit cell volume of a crystalline form and the expected space filling requirements of an API molecule can be used to determine if a crystalline material is likely to be multicomponent, such as a solvate, hydrate, salt, or a co-crystal. The unit cell information can be readily accessed from powder diffraction data alone utilizing powder indexing methodology. If the unit cell has additional space not likely attributable to the API entity, then there is either a void or another component within the crystal lattice. This "leftover" space can be used to determine the likely stoichiometry of the additional component. A simple approach for calculating the expected required volume for a given molecule within a crystal using an atom based additive approach will be discussed. Coupling this estimation with the actual unit cell volumes and space group information obtained from powder indexing allows for the rapid evaluation of the likely stoichiometry of multicomponent crystals using diffraction data alone. This approach is particularly useful for the early assessment of new phases during salt, co-crystal, and polymorph screening, and also for the characterization of stable and unstable solvates. PMID:25872584

  7. Assessment of the Stoichiometry of Multicomponent Crystals Using Only X-ray Powder Diffraction Data.

    PubMed

    Maguire, Courtney K; Brunskill, Andrew P J

    2015-06-01

    Knowledge of the unit cell volume of a crystalline form and the expected space filling requirements of an API molecule can be used to determine if a crystalline material is likely to be multicomponent, such as a solvate, hydrate, salt, or a co-crystal. The unit cell information can be readily accessed from powder diffraction data alone utilizing powder indexing methodology. If the unit cell has additional space not likely attributable to the API entity, then there is either a void or another component within the crystal lattice. This "leftover" space can be used to determine the likely stoichiometry of the additional component. A simple approach for calculating the expected required volume for a given molecule within a crystal using an atom based additive approach will be discussed. Coupling this estimation with the actual unit cell volumes and space group information obtained from powder indexing allows for the rapid evaluation of the likely stoichiometry of multicomponent crystals using diffraction data alone. This approach is particularly useful for the early assessment of new phases during salt, co-crystal, and polymorph screening, and also for the characterization of stable and unstable solvates.

  8. The MYTHEN detector for X-ray powder diffraction experiments at the Swiss Light Source

    PubMed Central

    Bergamaschi, Anna; Cervellino, Antonio; Dinapoli, Roberto; Gozzo, Fabia; Henrich, Beat; Johnson, Ian; Kraft, Philipp; Mozzanica, Aldo; Schmitt, Bernd; Shi, Xintian

    2010-01-01

    The MYTHEN single-photon-counting silicon microstrip detector has been developed at the Swiss Light Source for time-resolved powder diffraction experiments. An upgraded version of the detector has been installed at the SLS powder diffraction station allowing the acquisition of diffraction patterns over 120° in 2θ in fractions of seconds. Thanks to the outstanding performance of the detector and to the calibration procedures developed, the quality of the data obtained is now comparable with that of traditional high-resolution point detectors in terms of FWHM resolution and peak profile shape, with the additional advantage of fast and simultaneous acquisition of the full diffraction pattern. MYTHEN is therefore optimal for time-resolved or dose-critical measurements. The characteristics of the MYTHEN detector together with the calibration procedures implemented for the optimization of the data are described in detail. The refinements of two known standard powders are discussed together with a remarkable application of MYTHEN to organic compounds in relation to the problem of radiation damage. PMID:20724787

  9. X-ray Absorption Spectroscopic Quantification and Speciation Modeling of Sulfate Adsorption on Ferrihydrite Surfaces.

    PubMed

    Gu, Chunhao; Wang, Zimeng; Kubicki, James D; Wang, Xiaoming; Zhu, Mengqiang

    2016-08-01

    Sulfate adsorption on mineral surfaces is an important environmental chemical process, but the structures and respective contribution of different adsorption complexes under various environmental conditions are unclear. By combining sulfur K-edge XANES and EXAFS spectroscopy, quantum chemical calculations, and surface complexation modeling (SCM), we have shown that sulfate forms both outer-sphere complexes and bidentate-binuclear inner-sphere complexes on ferrihydrite surfaces. The relative fractions of the complexes vary with pH, ionic strength (I), and sample hydration degree (wet versus air-dried), but their structures remained the same. The inner-sphere complex adsorption loading decreases with increasing pH while remaining unchanged with I. At both I = 0.02 and 0.1 M, the outer-sphere complex loading reaches maximum at pH ∼5 and then decreases with pH, whereas it monotonically decreases with pH at I = 0.5 M. These observations result from a combination of the ionic-strength effect, the pH dependence of anion adsorption, and the competition between inner- and outer-sphere complexation. Air-drying drastically converts the outer-sphere complexes to the inner-sphere complexes. The respective contributions to the overall adsorption loading of the two complexes were directly modeled with the extended triple layer SCM by implementing the bidentate-binuclear inner-sphere complexation identified in the present study. These findings improve our understanding of sulfate adsorption and its effects on other environmental chemical processes and have important implications for generalizing the adsorption behavior of anions forming both inner- and outer-sphere complexes on mineral surfaces. PMID:27377619

  10. Adsorption structure of dimethyl ether on silicalite-1 zeolite determined using single-crystal X-ray diffraction

    PubMed Central

    Fujiyama, Shinjiro; Seino, Shintaro; Kamiya, Natsumi; Nishi, Koji; Yokomori, Yoshinobu

    2014-01-01

    The adsorption structures of dimethyl ether (DME) on silicalite-1 zeolite (MFI-type) are determined using single-crystal X-ray diffraction. The structure of low-loaded DME-silicalite-1 indicates that all DME molecules are located in the sinusoidal channel, which is the most stable sorption site based on the van der Waals interaction between DME and the framework. The configuration of guest molecules (linear or bent) plays an important role in determining where the stable sorption site is in the pore system of MFI-type zeolites. Bent molecules favor the sinusoidal channel, while linear molecules favor the straight channel. The contribution of DME–DME interactions is considerable in the high-loaded DME-silicalite-1 structure. PMID:25274519

  11. Electronic structure of cesium butyratouranylate(VI) as derived from DFT-assisted powder X-ray diffraction data.

    PubMed

    Vologzhanina, Anna V; Savchenkov, Anton V; Dmitrienko, Artem O; Korlyukov, Alexander A; Bushmarinov, Ivan S; Pushkin, Denis V; Serezhkina, Larisa B

    2014-10-16

    Investigation of chemical bonding and electronic structure of coordination polymers that do not form high-quality single crystals requires special techniques. Here, we report the molecular and electronic structure of the first cesium butyratouranylate, Cs[UO(2)(n-C(3)H(7)COO)(3)][UO(2)(n-C(3)H(7)COO)(OH)(H2O)], as obtained from DFT-assisted powder X-ray diffraction data because of the low quality of crystalline sample. The topological analysis of the charge distribution within the quantum theory of atoms-in-molecules (QTAIM) space partitioning and the distribution of electron localization function (ELF) is reported. The constancy of atomic domain of the uranium(VI) atom at different coordination numbers (7 and 8) and the presence of three ELF maxima in equatorial plane of an uranyl cation attributed to the 6s and 6p electrons were demonstrated for the first time. Details of methodologies applied for additional verification of the correctness of powder XRD refinement (Voronoi atomic descriptors and the Morse restraints) are discussed. PMID:25289686

  12. X-Ray diffraction on large single crystals using a powder diffractometer

    DOE PAGES

    Jesche, A.; Fix, M.; Kreyssig, A.; Meier, W. R.; Canfield, P. C.

    2016-06-16

    Information on the lattice parameter of single crystals with known crystallographic structure allows for estimations of sample quality and composition. In many cases it is sufficient to determine one lattice parameter or the lattice spacing along a certain, high- symmetry direction, e.g. in order to determine the composition in a substitution series by taking advantage of Vegard’s rule. Here we present a guide to accurate measurements of single crystals with dimensions ranging from 200 μm up to several millimeter using a standard powder diffractometer in Bragg-Brentano geometry. The correction of the error introduced by the sample height and the optimizationmore » of the alignment are discussed in detail. Finally, in particular for single crystals with a plate-like habit, the described procedure allows for measurement of the lattice spacings normal to the plates with high accuracy on a timescale of minutes.« less

  13. Catalyst Chemical State during CO Oxidation Reaction on Cu(111) Studied with Ambient-Pressure X-ray Photoelectron Spectroscopy and Near Edge X-ray Adsorption Fine Structure Spectroscopy.

    PubMed

    Eren, Baran; Heine, Christian; Bluhm, Hendrik; Somorjai, Gabor A; Salmeron, Miquel

    2015-09-01

    The chemical structure of a Cu(111) model catalyst during the CO oxidation reaction in the CO+O2 pressure range of 10-300 mTorr at 298-413 K was studied in situ using surface sensitive X-ray photoelectron and adsorption spectroscopy techniques [X-ray photoelectron spectroscopy (XPS) and near edge X-ray adsorption fine structure spectroscopy (NEXAFS)]. For O2:CO partial pressure ratios below 1:3, the surface is covered by chemisorbed O and by a thin (∼1 nm) Cu2O layer, which covers completely the surface for ratios above 1:3 between 333 and 413 K. The Cu2O film increases in thickness and exceeds the escape depth (∼3-4 nm) of the XPS and NEXAFS photoelectrons used for analysis at 413 K. No CuO formation was detected under the reaction conditions used in this work. The main reaction intermediate was found to be CO2(δ-), with a coverage that correlates with the amount of Cu2O, suggesting that this phase is the most active for CO oxidation.

  14. On the response of Y 3Al 5O 12: Ce (YAG: Ce) powder scintillating screens to medical imaging X-rays

    NASA Astrophysics Data System (ADS)

    Kandarakis, I.; Cavouras, D.; Sianoudis, I.; Nikolopoulos, D.; Episkopakis, A.; Linardatos, D.; Margetis, D.; Nirgianaki, E.; Roussou, M.; Melissaropoulos, P.; Kalivas, N.; Kalatzis, I.; Kourkoutas, K.; Dimitropoulos, N.; Louizi, A.; Nomicos, C.; Panayiotakis, G.

    2005-02-01

    The aim of this study was to examine Y 3Al 5O 12:Ce (also known as YAG:Ce) powder scintillator under X-ray imaging conditions. This material shows a very fast scintillation decay time and it has never been used in X-ray medical imaging. In the present study various scintillator layers (screens) with coating thickness ranging from 13 to 166 mg/cm 2 were prepared in our laboratory by sedimentation of Y 3Al 5O 12: Ce powder. Optical emission spectra and light emission efficiency (spectrum area over X-ray exposure) of the layers were measured under X-ray excitation using X-ray tube voltages (80-120 kVp) often employed in general medical radiography and fluoroscopy. Spectral compatibility with various optical photon detectors (photodiodes, photocathodes, charge coupled devices, films) and intrinsic conversion efficiency values were determined using emission spectrum data. In addition, parameters related to X-ray detection, energy absorption efficiency and K-fluorescence characteristic emission were calculated. A theoretical model describing radiation and light transfer through scattering media was used to fit experimental data. Intrinsic conversion efficiency (η≈0.03-0.05) and light attenuation coefficients (σ≈26.5 cm/g) were derived through this fitting. Y 3Al 5O 12:Ce showed peak emission in the wavelength range 530-550 nm. The light emission efficiency was found to be maximum for the 107 mg/cm 2 layer. Due to its "green" emission spectrum, Y 3Al 5O 12:Ce showed excellent compatibility (of the order of 0.9) with the sensitivity of many currently used photodetectors. Taking into account its very fast response Y 3Al 5O 12:Ce could be considered for application in X-ray imaging especially in various digital detectors.

  15. Possibilities and limitations of synchrotron X-ray powder diffraction with double crystal and double multilayer monochromators for microscopic speciation studies

    NASA Astrophysics Data System (ADS)

    De Nolf, Wout; Jaroszewicz, Jakub; Terzano, Roberto; Lind, Ole Christian; Salbu, Brit; Vekemans, Bart; Janssens, Koen; Falkenberg, Gerald

    2009-08-01

    The performance of a combined microbeam X-ray fluorescence/X-ray powder diffraction (XRF/XRPD) measurement station at Hamburger Synchrotronstrahlungslabor (HASYLAB) Beamline L is discussed in comparison to that at European Synchrotron Radiation Facility (ESRF) ID18F/ID22. The angular resolution in the X-ray diffractograms is documented when different combinations of X-ray source, optics and X-ray diffraction detectors are employed. Typical angular resolution values in the range 0.3-0.5° are obtained at the bending magnet source when a 'pink' beam form of excitation is employed. A similar setup at European Synchrotron Radiation Facility beamlines ID18F and ID22 allows to reach angular resolution values of 0.1-0.15°. In order to document the possibilities and limitations for speciation of metals in environmental materials by means of Hamburger Synchrotronstrahlungslabor Beamline L X-ray fluorescence/X-ray powder diffraction setup, two case studies are discussed, one involved in the identification of the crystal phases in which heavy metals such as chromium, iron, barium and lead are present in polluted soils of an industrial site (Val Basento, Italy) and another involved in the speciation of uranium in depleted uranium particles (Ceja Mountains, Kosovo). In the former case, the angular resolution is sufficient to allow identification of most crystalline phases present while in the latter case, it is necessary to dispose of an angular resolution of ca. 0.2° to distinguish between different forms of oxidized uranium.

  16. An Investigation of X-ray Luminosity versus Crystalline Powder Granularity

    SciTech Connect

    Borade, Ramesh; Bourret-Courchesne, Edith; ,

    2012-03-07

    At the High-throughput Discovery of Scintillator Materials Facility at Lawrence Berkeley National Laboratory, scintillators are synthesized by solid-state reaction or melt mixing, forming crystalline powders. These powders are formed in various granularity and the crystal grain size affects the apparent luminosity of the scintillator. To accurately predict a "full-size" scintillator's crystal luminosity, the crystal luminosity as a function of crystal granularity size has to be known. In this study, we examine Bi{sub 4}Ge{sub 3}O{sub 12} (BGO), Lu{sub 2}SiO{sub 5}:Ce (LSO), YAlO{sub 3}:Ce (YAP:Ce), and CsBa{sub 2}I{sub 5}:Eu{sup 2+} (CBI) luminosities as a function of crystalline grain size. The highest luminosities were measured for 600- to 1000-{micro}m crystal grain sizes for BGO and LSO, for 310- to 600-{micro}m crystal grain sizes for CBI, and for crystal grains larger than 165{micro}m for YAP:Ce. Crystal grains that were larger than 1 mm had a lower packing fraction, and smaller grains were affected by internal scattering. We measured a 34% decrease in luminosity for BGO when decreasing from the 600- to 1000- {micro}m crystal grain size range down to the 20- to 36-{micro}m range. The corresponding luminosity decrease for LSO was 44% for the same grain size decrease. YAP:Ce exhibited a luminosity decrease of 47% when the grain size decreased from the 165- to 310-{micro}m crystal grains to the 20- to 36-{micro}m range, and CBI exhibited a luminosity decrease of 98% when the grain size decreased from the 310- to 600-{micro}m crystal grain range to the 36- to 50-{micro}m range. We were able to very accurately estimate full-size crystal luminosities from crystalline grains that are larger than 90 {micro}m.

  17. Water adsorption on TiO2 surfaces probed by soft X-ray spectroscopies: bulk materials vs. isolated nanoparticles

    PubMed Central

    Benkoula, Safia; Sublemontier, Olivier; Patanen, Minna; Nicolas, Christophe; Sirotti, Fausto; Naitabdi, Ahmed; Gaie-Levrel, François; Antonsson, Egill; Aureau, Damien; Ouf, François-Xavier; Wada, Shin-Ichi; Etcheberry, Arnaud; Ueda, Kiyoshi; Miron, Catalin

    2015-01-01

    We describe an experimental method to probe the adsorption of water at the surface of isolated, substrate-free TiO2 nanoparticles (NPs) based on soft X-ray spectroscopy in the gas phase using synchrotron radiation. To understand the interfacial properties between water and TiO2 surface, a water shell was adsorbed at the surface of TiO2 NPs. We used two different ways to control the hydration level of the NPs: in the first scheme, initially solvated NPs were dried and in the second one, dry NPs generated thanks to a commercial aerosol generator were exposed to water vapor. XPS was used to identify the signature of the water layer shell on the surface of the free TiO2 NPs and made it possible to follow the evolution of their hydration state. The results obtained allow the establishment of a qualitative determination of isolated NPs’ surface states, as well as to unravel water adsorption mechanisms. This method appears to be a unique approach to investigate the interface between an isolated nano-object and a solvent over-layer, paving the way towards new investigation methods in heterogeneous catalysis on nanomaterials. PMID:26462615

  18. Locating Organic Guests in Inorganic Host Materials from X-ray Powder Diffraction Data.

    PubMed

    Smeets, Stef; McCusker, Lynne B; Baerlocher, Christian; Elomari, Saleh; Xie, Dan; Zones, Stacey I

    2016-06-01

    Can the location of the organic structure-directing agent (SDA) inside the channel system of a zeolite be determined experimentally in a systematic manner? In an attempt to answer this question, we investigated six borosilicate zeolites of known framework structure (SSZ-53, SSZ-55, SSZ-56, SSZ-58, SSZ-59, and SSZ-60), where the location of the SDA had only been simulated using molecular modeling techniques in previous studies. From synchrotron powder diffraction data, we were able to retrieve reliable experimental positions for the SDA by using a combination of simulated annealing (global optimization) and Rietveld refinement. In this way, problems arising from data quality and only partially compatible framework and SDA symmetries, which can lead to indecipherable electron density maps, can be overcome. Rietveld refinement using geometric restraints were then performed to optimize the positions and conformations of the SDAs. With these improved models, it was possible to go on to determine the location of the B atoms in the framework structure. That is, two pieces of information that are key to the understanding of zeolite synthesis-the location of the organic SDA in the channel system and of the positions adopted by heteroatoms in the silicate framework-can be extracted from experimental data using a systematic strategy. In most cases, the locations of the SDAs determined experimentally compare well with those simulated with molecular modeling, but there are also some clear differences, and the reason for these differences can be understood. The approach is generally applicable, and has also been used to locate organic guests, linkers, and ligands in metal-organic compounds. PMID:27181421

  19. X-ray Powder Diffraction in Conservation Science: Towards Routine Crystal Structure Determination of Corrosion Products on Heritage Art Objects.

    PubMed

    Dinnebier, Robert E; Fischer, Andrea; Eggert, Gerhard; Runčevski, Tomče; Wahlberg, Nanna

    2016-01-01

    The crystal structure determination and refinement process of corrosion products on historic art objects using laboratory high-resolution X-ray powder diffraction (XRPD) is presented in detail via two case studies. The first material under investigation was sodium copper formate hydroxide oxide hydrate, Cu4Na4O(HCOO)8(OH)2∙4H2O (sample 1) which forms on soda glass/copper alloy composite historic objects (e.g., enamels) in museum collections, exposed to formaldehyde and formic acid emitted from wooden storage cabinets, adhesives, etc. This degradation phenomenon has recently been characterized as "glass induced metal corrosion". For the second case study, thecotrichite, Ca3(CH3COO)3Cl(NO3)2∙6H2O (sample 2), was chosen, which is an efflorescent salt forming needlelike crystallites on tiles and limestone objects which are stored in wooden cabinets and display cases. In this case, the wood acts as source for acetic acid which reacts with soluble chloride and nitrate salts from the artifact or its environment. The knowledge of the geometrical structure helps conservation science to better understand production and decay reactions and to allow for full quantitative analysis in the frequent case of mixtures. PMID:27341300

  20. X-ray Powder Diffraction in Conservation Science: Towards Routine Crystal Structure Determination of Corrosion Products on Heritage Art Objects.

    PubMed

    Dinnebier, Robert E; Fischer, Andrea; Eggert, Gerhard; Runčevski, Tomče; Wahlberg, Nanna

    2016-01-01

    The crystal structure determination and refinement process of corrosion products on historic art objects using laboratory high-resolution X-ray powder diffraction (XRPD) is presented in detail via two case studies. The first material under investigation was sodium copper formate hydroxide oxide hydrate, Cu4Na4O(HCOO)8(OH)2∙4H2O (sample 1) which forms on soda glass/copper alloy composite historic objects (e.g., enamels) in museum collections, exposed to formaldehyde and formic acid emitted from wooden storage cabinets, adhesives, etc. This degradation phenomenon has recently been characterized as "glass induced metal corrosion". For the second case study, thecotrichite, Ca3(CH3COO)3Cl(NO3)2∙6H2O (sample 2), was chosen, which is an efflorescent salt forming needlelike crystallites on tiles and limestone objects which are stored in wooden cabinets and display cases. In this case, the wood acts as source for acetic acid which reacts with soluble chloride and nitrate salts from the artifact or its environment. The knowledge of the geometrical structure helps conservation science to better understand production and decay reactions and to allow for full quantitative analysis in the frequent case of mixtures.

  1. [X-ray powder diffraction of clay minerals of SZK01 core of Zabuye Lake, Tibetan Plateau].

    PubMed

    Zhang, Xue-Fei; Zheng, Mian-Ping

    2014-11-01

    The present article chooses the core from the borehole SZK01 in Zabuye Lake as the main research object. According to the results of X-ray powder diffraction of clay minerals, the major components are illite, illite and smectite mixed layer mineral (I/S), kaolinite and chlorite. According to the different species and contents of clay, integration of the characteristics of mineral and the results of Δ18O, we reestablished the evolution process of paleoclimate in Zabuye Lake. In compaison with SZK02 core in Zabuye, Greenland GISP2 and GRIP and Guliya ice core, it contains 5 stages since 115 ka in Zabuye: the last interglacial (15-75.5 ka), the earlier last glacial (75.5-60 ka), the interstage of the last glacial (60-30.1 ka), the last glacial maximum (30.1-16.7 ka) and deglacial-holocene (since 16.7 ka). We also recognized 6 Heinrich events (H1-H6) and warm event in 71 ka. In particular, the content of kaolinite is low, with the negative-skewed value of Δ18O in 52-53 ka, while the value of Δ18O in SZK02 and Guliya ice core is negative-skewed too, indicating the cold event in Tibet plateau, named H5-1. All the above demonstrated that the climate in Tibet plateau is global since the earlier last glacial, and it also has regional characteristics. PMID:25752070

  2. Ultrafast inter-ionic charge transfer of transition-metal complexes mapped by femtosecond X-ray powder diffraction

    SciTech Connect

    Freyer, Benjamin; Zamponi, Flavio; Juve, Vincent; Stingl, Johannes; Woerner, Michael; Elsaesser, Thomas; Chergui, Majed

    2013-04-14

    The transient electronic and molecular structure arising from photoinduced charge transfer in transition metal complexes is studied by X-ray powder diffraction with a 100 fs temporal and atomic spatial resolution. Crystals containing a dense array of Fe(II)-tris(bipyridine) ([Fe(bpy){sub 3}]{sup 2+}) complexes and their PF{sub 6}{sup -} counterions display pronounced changes of electron density that occur within the first 100 fs after two-photon excitation of a small fraction of the [Fe(bpy){sub 3}]{sup 2+} complexes. Transient electron density maps derived from the diffraction data reveal a transfer of electronic charge from the Fe atoms and-so far unknown-from the PF{sub 6}{sup -} counterions to the bipyridine units. Such charge transfer (CT) is connected with changes of the inter-ionic and the Fe-bipyridine distances. An analysis of the electron density maps demonstrates the many-body character of charge transfer which affects approximately 30 complexes around a directly photoexcited one. The many-body behavior is governed by the long-range Coulomb forces in the ionic crystals and described by the concept of electronic polarons.

  3. [X-ray powder diffraction of clay minerals of SZK01 core of Zabuye Lake, Tibetan Plateau].

    PubMed

    Zhang, Xue-Fei; Zheng, Mian-Ping

    2014-11-01

    The present article chooses the core from the borehole SZK01 in Zabuye Lake as the main research object. According to the results of X-ray powder diffraction of clay minerals, the major components are illite, illite and smectite mixed layer mineral (I/S), kaolinite and chlorite. According to the different species and contents of clay, integration of the characteristics of mineral and the results of Δ18O, we reestablished the evolution process of paleoclimate in Zabuye Lake. In compaison with SZK02 core in Zabuye, Greenland GISP2 and GRIP and Guliya ice core, it contains 5 stages since 115 ka in Zabuye: the last interglacial (15-75.5 ka), the earlier last glacial (75.5-60 ka), the interstage of the last glacial (60-30.1 ka), the last glacial maximum (30.1-16.7 ka) and deglacial-holocene (since 16.7 ka). We also recognized 6 Heinrich events (H1-H6) and warm event in 71 ka. In particular, the content of kaolinite is low, with the negative-skewed value of Δ18O in 52-53 ka, while the value of Δ18O in SZK02 and Guliya ice core is negative-skewed too, indicating the cold event in Tibet plateau, named H5-1. All the above demonstrated that the climate in Tibet plateau is global since the earlier last glacial, and it also has regional characteristics.

  4. Direct determination of trace elements in boron nitride powders by slurry sampling total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Amberger, Martin A.; Höltig, Michael; Broekaert, José A. C.

    2010-02-01

    The use of slurry sampling total reflection X-ray fluorescence spectrometry (SlS-TXRF) for the direct determination of Ca, Cr, Cu, Fe, Mn and Ti in four boron nitride powders has been described. Measurements of the zeta potential showed that slurries with good stabilities can be obtained by the addition of polyethylenimine (PEI) at a concentration of 0.1 wt.% and by adjusting the pH at 4. For the optimization of the concentration of boron nitride in the slurries the net line intensities and the signal to background ratios were determined for the trace elements Ca and Ti as well as for the internal standard element Ga in the case of concentrations of boron nitride ranging from 1 to 30 mg mL -1. As a compromise with respect to high net line intensities and high signal to background ratios, concentrations of 5 mg mL -1 of boron nitride were found suitable and were used for all further measurements. The limits of detection of SlS-TXRF for the boron nitride powders were found to range from 0.062 to 1.6 μg g - 1 for Cu and Ca, respectively. Herewith, they are higher than those obtained in solid sampling and slurry sampling graphite furnace atomic absorption spectrometry (SoS-GFAAS, SlS-GFAAS) as well as those of solid sampling electrothermal evaporation inductively coupled plasma optical emission spectrometry (SoS-ETV-ICP-OES). For Ca and Fe as well as for Cu and Fe, however, they were found to be lower than for GFAAS and for ICP-OES subsequent to wet chemical digestion, respectively. The universal applicability of SlS-TXRF to the analysis of samples with a wide variety of matrices could be demonstrated by the analysis of certified reference materials such as SiC, Al 2O 3, powdered bovine liver and borate ore with a single calibration. The correlation coefficients of the plots for the values found for Ca, Fe and Ti by SlS-TXRF in the boron nitride powders as well as in the before mentioned samples versus the reference values for the respective samples over a

  5. Alternative matrix formers for nanosuspension solidification: Dissolution performance and X-ray microanalysis as an evaluation tool for powder dispersion.

    PubMed

    Van Eerdenbrugh, Bernard; Froyen, Ludo; Van Humbeeck, Jan; Martens, Johan A; Augustijns, Patrick; Van Den Mooter, Guy

    2008-11-15

    Four alternative matrix formers [Avicel PH101, Fujicalin (CaHPO(4)), Aerosil 200 (SiO(2)) and Inutec SP1] were evaluated for their capability in preserving rapid dissolution after spray-drying of nanosuspensions. Model drug compounds selected were cinnarizine (CIN), itraconazole (ITR) and phenylbutazone (PHB) as they showed a decrease in dissolution rate upon spray-drying in the absence of additional matrix formers, yielding release values after 5min of dissolution (release(5min)) of 57.7+/-1.0% (CIN), 56.3+/-3.8% (ITR) and 67.4+/-1.3% (PHB). Compared to the situation without matrix former inclusion, the performance of Avicel PH101 was good for CIN (release(5min)=90.9+/-7.7%), intermediate for PHB (release(5min)=81.0+/-6.4%) and poor for ITR (release(5min)=42.1+/-4.2%). For Fujicalin, intermediate (PHB: release(5min)=87.7+/-3.0%) or poor (CIN: release(5min)=66.1+/-3.4%; ITR: release(5min)=55.9+/-5.2%) performance was seen. Results for Aerosil 200 were good for all compounds (CIN: release(5min)=91.5+/-2.5%; ITR: release(5min)=83.8+/-3.4%; PHB: release(5min)=95.5+/-2.4%), indicating that the large specific surface area was in this case translated into good matrix forming capabilities. Finally, the best results were obtained for Inutec SP1 (CIN: release(5min)=88.7+/-1.2%; ITR: release(5min)=93.4+/-2.4%; PHB: release(5min)=101.3+/-4.9%). Except for Avicel PH101, Cl-maps from X-ray microanalysis of the itraconazole powders supported the hypothesis that better dispersion of drug in the powders results in faster dissolution.

  6. Hydrostatic Compression Curve for Triamino-Trinitrobenzene Determined to 13.0 GPa with Powder X-Ray Diffraction

    SciTech Connect

    Stevens, Lewis L.; Velisavljevic, Nenad; Hooks, Daniel E.; Dattelbaum, Dana M.

    2008-08-22

    Using powder X-ray diffraction in conjunction with a diamond anvil cell (DAC), the unit cell volume of triamino-trinitrobenzene (TATB) has been measured from ambient pressure to 13 GPa. The resultant isotherm is compared with previous theoretical (Byrd and Rice and Pastine and Bernecker) and experimental (Olinger and Cady) works. While all reports are consistent to approximately 2 GPa, our measurements reveal a slightly stiffer TATB material than reported by Olinger and Cady and an intermediate compressibility compared with the isotherms predicted by the two theoretical works. Analysis of the room temperature isotherm using the semi-empirical, Murnaghan, Birch-Murnaghan, and Vinet equations of state (EOS) provided a determination of the isothermal bulk modulus (K{sub 0}) and its pressure-derivative (K{sub 0}') for TATB. From these fits to our P-V isotherm, from ambient pressure to 8 GPa, the average results for the zero-pressure bulk modulus and its pressure derivative were found to be 14.7 GPa and 10.1, respectively. For comparison to shock experiments on pressed TATB powder and its plastic-bonded formulation PBX 9502 (95% TATB, 5% Kel-F 800), the isotherm was transformed to the pseudo-velocity U{sub s}-u{sub p} plane using the Rankine-Hugoniot jump conditions. This analysis provides an extrapolated bulk sound speed, c{sub 0}=1.70 km s{sup -1}, for TATB and its agreement with a previous determination (c{sub 0}=1.43 km s{sup -1}) is discussed. Furthermore, our P-V and corresponding U{sub s}-u{sub p} curves reveal a subtle cusp at approximately 8 GPa. This cusp is discussed in relation to similar observations made for the aromatic hydrocarbons anthracene, benzene and toluene, graphite, and trinitrotoluene (TNT).

  7. Acemetacin cocrystals and salts: structure solution from powder X-ray data and form selection of the piperazine salt.

    PubMed

    Sanphui, Palash; Bolla, Geetha; Nangia, Ashwini; Chernyshev, Vladimir

    2014-03-01

    Acemetacin (ACM) is a non-steroidal anti-inflammatory drug (NSAID), which causes reduced gastric damage compared with indomethacin. However, acemetacin has a tendency to form a less soluble hydrate in the aqueous medium. We noted difficulties in the preparation of cocrystals and salts of acemetacin by mechanochemical methods, because this drug tends to form a hydrate during any kind of solution-based processing. With the objective to discover a solid form of acemetacin that is stable in the aqueous medium, binary adducts were prepared by the melt method to avoid hydration. The coformers/salt formers reported are pyridine carboxamides [nicotinamide (NAM), isonicotinamide (INA), and picolinamide (PAM)], caprolactam (CPR), p-aminobenzoic acid (PABA), and piperazine (PPZ). The structures of an ACM-INA cocrystal and a binary adduct ACM-PABA were solved using single-crystal X-ray diffraction. Other ACM cocrystals, ACM-PAM and ACM-CPR, and the piperazine salt ACM-PPZ were solved from high-resolution powder X-ray diffraction data. The ACM-INA cocrystal is sustained by the acid⋯pyridine heterosynthon and N-H⋯O catemer hydrogen bonds involving the amide group. The acid⋯amide heterosynthon is present in the ACM-PAM cocrystal, while ACM-CPR contains carboxamide dimers of caprolactam along with acid-carbonyl (ACM) hydrogen bonds. The cocrystals ACM-INA, ACM-PAM and ACM-CPR are three-dimensional isostructural. The carboxyl⋯carboxyl synthon in ACM-PABA posed difficulty in assigning the position of the H atom, which may indicate proton disorder. In terms of stability, the salts were found to be relatively stable in pH 7 buffer medium over 24 h, but the cocrystals dissociated to give ACM hydrate during the same time period. The ACM-PPZ salt and ACM-nicotinamide cocrystal dissolve five times faster than the stable hydrate form, whereas the ACM-PABA adduct has 2.5 times faster dissolution rate. The pharmaceutically acceptable piperazine salt of acemetacin exhibits superior

  8. Acemetacin cocrystals and salts: structure solution from powder X-ray data and form selection of the piperazine salt

    PubMed Central

    Sanphui, Palash; Bolla, Geetha; Nangia, Ashwini; Chernyshev, Vladimir

    2014-01-01

    Acemetacin (ACM) is a non-steroidal anti-inflammatory drug (NSAID), which causes reduced gastric damage compared with indomethacin. However, acemetacin has a tendency to form a less soluble hydrate in the aqueous medium. We noted difficulties in the preparation of cocrystals and salts of acemetacin by mechanochemical methods, because this drug tends to form a hydrate during any kind of solution-based processing. With the objective to discover a solid form of acemetacin that is stable in the aqueous medium, binary adducts were prepared by the melt method to avoid hydration. The coformers/salt formers reported are pyridine carboxamides [nicotinamide (NAM), isonicotinamide (INA), and picolinamide (PAM)], caprolactam (CPR), p-aminobenzoic acid (PABA), and piperazine (PPZ). The structures of an ACM–INA cocrystal and a binary adduct ACM–PABA were solved using single-crystal X-ray diffraction. Other ACM cocrystals, ACM–PAM and ACM–CPR, and the piperazine salt ACM–PPZ were solved from high-resolution powder X-ray diffraction data. The ACM–INA cocrystal is sustained by the acid⋯pyridine heterosynthon and N—H⋯O catemer hydrogen bonds involving the amide group. The acid⋯amide heterosynthon is present in the ACM–PAM cocrystal, while ACM–CPR contains carboxamide dimers of caprolactam along with acid–carbonyl (ACM) hydrogen bonds. The cocrystals ACM–INA, ACM–PAM and ACM–CPR are three-dimensional isostructural. The carboxyl⋯carboxyl synthon in ACM–PABA posed difficulty in assigning the position of the H atom, which may indicate proton disorder. In terms of stability, the salts were found to be relatively stable in pH 7 buffer medium over 24 h, but the cocrystals dissociated to give ACM hydrate during the same time period. The ACM–PPZ salt and ACM–nicotinamide cocrystal dissolve five times faster than the stable hydrate form, whereas the ACM–PABA adduct has 2.5 times faster dissolution rate. The pharmaceutically acceptable piperazine

  9. Mechanism of Pb Adsorption to Fatty Acid Langmuir Monolayers Studied by X-ray Absorption Fine Structure Spectroscopy

    SciTech Connect

    Boyanov, M.I.; Kmetko, J.; Shibata, T.; Datta, A.; Dutta, P.; Bunker, B.A.

    2010-09-30

    The local atomic environment of lead (Pb) adsorbed to a CH{sub 3}(CH{sub 2}){sub 19}COOH Langmuir monolayer was investigated in situ using grazing-incidence X-ray absorption fine structure (GI-XAFS) spectroscopy at the Pb L{sub III} edge. Measurements were performed at pH 6.5 of the 10{sup -5} M PbCl{sub 2} solution subphase, a condition under which grazing incidence diffraction (GID) revealed a large-area commensurate superstructure underneath the close-packed organic monolayer. The XAFS results indicate covalent binding of the Pb cations to the carboxyl headgroups, and the observed Pb-Pb coordination suggests that the metal is adsorbed as a hydrolysis polymer, rather than as individual Pb{sup 2+} ions. The data are consistent with a bidentate chelating mechanism and a one Pb atom to one carboxyl headgroup binding stoichiometry. We discuss how this adsorption model can explain the peculiarities observed with Pb in previous metal-Langmuir monolayer studies. A systematic study of lead perchlorate and lead acetate aqueous solutions is presented and used in the analysis. XAFS multiple scattering effects from alignment of the Pb-C-C atoms in the lead acetate solutions are reported.

  10. Adsorption of water to the metal/polymer interface studied by neutron and X-ray reflectivity

    SciTech Connect

    Kent, M.S.; McIntyre, D.C.; Smith, G.S.; Baker, S.; Wages, S.; Nyitray, A.; Browning, J.; Hua, Duen-Wu

    1993-12-31

    Neutron reflectivity is among the few techniques able to probe a buried interface. Through the use of isotopic labeling, complicated interface structures may be determined with a resolution on the order of 5 {angstrom}. However, for highly complex thin film and interface structures, it is often necessary to perform complementary experiments to reduce the number of unknown variables, and thus enable an unambiguous interpretation of the neutron reflectivity. To this end, the authors have combined X-ray and neutron reflectivity to study changes in a metal/polymer interface (molybdenum/polyurethane, hereafter Mo/PU) upon exposure to a humid environment. In particular, the authors have tracked the adsorption of moisture to the interface and variations in the density of the interphase. This information was obtained as a function of the concentration of a silane coupling agent added to the bulk of the PU. Adhesion of the Mo/PU interface is important to programs in the DOE complex. This paper reports the first results of this study.

  11. 1,1'-Methylenedipyridinium tetrachloridocuprate(II) and bis[tetrachloridoaurate(III)] hybrid salts by X-ray powder diffraction.

    PubMed

    Al-Ktaifani, Mahmoud; Rukiah, Mwaffak

    2012-09-01

    In order to explore the potential propensity of the 1,1'-methylenedipyridinium dication to form organic-inorganic hybrid ionic compounds by reaction with the appropriate halide metal salt, the organic-inorganic hybrid salts 1,1'-methylenedipyridinium tetrachloridocuprate(II), (C(11)H(12)N(2))[CuCl(4)], (I), and 1,1'-methylenedipyridinium bis[tetrachloridoaurate(III)], (C(11)H(12)N(2))[AuCl(4)](2), (II), were obtained by treatment of 1,1'-methylenedipyridinium dichloride with CuCl(2) and Na[AuCl(4)], respectively. Both hybrid salts were isolated as pure compounds, fully characterized by multinuclear NMR spectroscopy and their molecular structures confirmed by powder X-ray diffraction studies. The crystal structures consist of discrete 1,1'-methylenedipyridinium dications and [CuCl(4)](2-) and [AuCl(4)](-) anions for (I) and (II), respectively. As expected, the dications form a butterfly shape; the Cu(II) centre of [CuCl(4)](2-) has a distorted tetrahedral configuration and the Au(III) centre of [AuCl(4)](-) shows a square-planar coordination. The ionic species of (I) and the dication of (II) each have twofold axial symmetry, while the two [AuCl(4)](-) anions are located on a mirror-plane site. Both crystal structures are stabilized by intermolecular C-H···Cl hydrogen bonds and also by Cl···π interactions. It is noteworthy that, while the average intermolecular centroid-centroid pyridinium ring distance in (I) is 3.643 (8) Å, giving strong evidence for noncovalent π-π ring interactions, for (II), the shortest centroid-centroid distance between pyridinium rings of 5.502 (9) Å is too long for any significant π-π ring interactions, which might be due to the bulk of the two [AuCl(4)](-) anions. PMID:22935491

  12. A glass capillary cell for in situ powder X-ray diffraction of condensed volatile compounds. Solid HCFC-123a and HCFC-124.

    PubMed

    Brunelli, Michela; Fitch, Andrew N

    2003-07-01

    A rotating glass capillary cell with a gas handling system has been built to allow in situ studies by powder X-ray diffraction. The cell can be used to condense volatile compounds, or to follow solid-state chemical reactions under vacuum or at gas pressures up to around 7 x 10(5) Pa. Using the cell, cooled by a stream of helium gas, the solid phases of 1,2-dichlorotrifluoroethane (HCFC-123a) and 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124) have been investigated using powder synchrotron X-ray radiation. These were found to have disordered hexagonal structures, with a = 4.018 (5), c = 6.553 (1) A and a = 4.048 (1), c = 6.625 (1) A, respectively, at 64 K. PMID:12824935

  13. Additional evidence from x-ray powder diffraction patterns that icosahedral quasi-crystals of intermetallic compounds are twinned cubic crystals

    SciTech Connect

    Pauling, L. )

    1988-07-01

    Analysis of the measured values of Q for the weak peaks (small maxima, usually considered to be background fluctuations, noise) on the x-ray powder diffraction curves for 17 rapidly quenched alloys leads directly to the conclusion that they are formed by an 820-atom or 1012-atom primitive cubic structure that by icosahedral twinning produces the so-called icosahedral quasi-crystals.

  14. Comparison of Shock-Deformed Carbonate Samples to Unshocked Carbonate Samples Using X-ray Powder Diffraction

    NASA Astrophysics Data System (ADS)

    Huson, S.; Foit, F.; Pope, M.

    2006-12-01

    Previous studies of carbonate minerals from meteorite impact craters have revealed broader X-ray powder diffraction (XRD) peaks when compared to those of unshocked mineral standards. In this study XRD patterns of shocked minerals from an impact crater are compared to those subjected to terrestrial tectonic processes as well as to undeformed mineral standards from our in-house collection. Shocked dolostone and limestone samples were collected from the central uplift and eroded crater rim of Sierra Madera, a well-exposed, complex impact crater located in west Texas. Unshocked samples of dolostone and limestone were collected from the Mission Canyon Formation of the Madison Limestone Group of southwest Montana and western Wyoming. The Mission Canyon Formation was deposited in a shallow shelf environment during the Mississippian, subsequently buried to varying depths, and deformed during the Laramide and Sevier orogenies in the Cretaceous. These samples are therefore excellent representatives for "normal" terrestrial tectonic processes. Samples were powdered, sieved through a 63 μm mesh sieve to ensure a uniform size, and sifted onto a vaseline coated zero background plate to reduce preferred orientation of grains. Patterns were collected over the range from 15° 120° 2θ with a step width of 0.02° 2θ and count-time of 10s per step. All patterns were analyzed using MDI Jade 7.0 software. Generally, samples collected in the field have XRD patterns that are not as sharp as the mineral standard patterns. With both shocked and unshocked samples, those containing dolomite show more XRD peak broadening than those without dolomite and at least one pattern of an unshocked dolostone sample is indistinguishable from a shocked dolostone pattern. However, dolostone samples in general are problematic. Previous researchers reported that the amount of magnesium in calcite may affect grinding properties and, therefore, influence XRD peak broadening. Currently, it is not always

  15. Bioactivity of 1.25CaO.SiO2 glass: an FTIR and X-ray study on powdered samples.

    PubMed

    Branda, F; Fresa, R; Costantini, A; Buri, A

    1996-12-01

    Powdered samples (170-230 mesh) of a glass of composition 1.25CaO.SiO2 were soaked in a simulated body fluid (SBF). The powders were submitted to Fourier transform infrared transmission spectroscopy as coarse powders (such as drawn out from the SBF) and as fine powders (soaked and subsequently ground). Soaked samples were submitted to differential thermal analysis (DTA) and the crystalline phases formed during heating in the DTA apparatus were identified by means of X-ray diffraction analysis. The method appears to be useful in studying the mechanism of deposition of the hydroxyapatite layer. It is documented, by using the same method, that the mechanism involves the reactions of hydrolysis and successive condensation and repolymerization of the silicate substrate. These reactions are very fast. Extensive Ca2+ cation depletion occurs, but appears to be slower. PMID:8968519

  16. Conformational analysis of an acyclic tetrapeptide: ab-initio structure determination from X-ray powder diffraction, Hirshfeld surface analysis and electronic structure.

    PubMed

    Das, Uday; Naskar, Jishu; Mukherjee, Alok Kumar

    2015-12-01

    A terminally protected acyclic tetrapeptide has been synthesized, and the crystal structure of its hydrated form, Boc-Tyr-Aib-Tyr-Ile-OMe·2H2O (1), has been determined directly from powder X-ray diffraction data. The backbone conformation of tetrapeptide (1) exhibiting two consecutive β-turns is stabilized by two 4 → 1 intramolecular N-H · · · O hydrogen bonds. In the crystalline state, the tetrapeptide molecules are assembled through water-mediated O-H · · · O hydrogen bonds to form two-dimensional molecular sheets, which are further linked by intermolecular C-H · · · O hydrogen bonds into a three-dimensional supramolecular framework. The molecular electrostatic potential (MEP) surface of (1) has been used to supplement the crystallographic observations. The nature of intermolecular interactions in (1) has been analyzed quantitatively through the Hirshfeld surface and two-dimensional fingerprint plot. The DFT optimized molecular geometry of (1) agrees closely with that obtained from the X-ray structure analysis. The present structure analysis of Boc-Tyr-Aib-Tyr-Ile-OMe·2H2 O (1) represents a case where ab-initio crystal structure of an acyclic tetrapeptide with considerable molecular flexibility has been accomplished from laboratory X-ray powder diffraction data.

  17. High pressure single crystal x-ray and neutron powder diffraction study of the ferroelectric-paraelectric phase transition in PbTiO3

    NASA Astrophysics Data System (ADS)

    Al-Zein, A.; Bouvier, P.; Kania, A.; Levelut, C.; Hehlen, B.; Nassif, V.; Hansen, T. C.; Fertey, P.; Haines, J.; Rouquette, J.

    2015-12-01

    The results obtained by high pressure neutron powder diffraction and single-crystal x-ray diffraction for the P4mm-Pm \\bar{3} m phase transition in the prototype ferroelectric perovskite lead titanate are shown. Neutron diffraction is found to be strongly sensitive to the dipolar moment in the PbTiO3 unit cell due to the gradual reduction of the displacement of the Ti and O atoms from centrosymmetric positions in the cubic perovskite structure which exhibits anti-phase scattering of Pb, Ti and O atoms. From applying both techniques, the anomalously high Debye-Waller factor for the lead atoms confirms the disordered character of the cubic phase. High pressure single crystal x-ray diffraction also perfectly describes the ferroelectric-paraelectric transition and will be the technique of choice to solve higher pressure structures for PbTiO3.

  18. Evidence from x-ray and neutron powder diffraction patterns that the so-called icosahedral and decagonal quasicrystals of MnAl/sub 6/ and other alloys are twinned cubic crystals

    SciTech Connect

    Pauling, L.

    1987-06-01

    It is shown that the x-ray powder diffraction patterns of rapidly quenched MnAl/sub 6/ and Mg/sub 32/(Al,Zn)/sub 49/ and the neutron powder diffraction pattern of MnAl/sub 5/ are compatible with the proposed 820-atom primitive cubic structure. The values found for the edge of the unit cube are 23.365 A (x-ray) and 23.416 A (neutron) for MnAl/sub 6/ and 24.313 A (x-ray) for Mg/sub 32/(Al,Zn)/sub 49/.

  19. X-ray photoelectron spectroscopy and x-ray absorption near edge structure study of copper sites hosted at the internal surface of ZSM-5 zeolite: A comparison with quantitative and energetic data on the CO and NH3 adsorption

    NASA Astrophysics Data System (ADS)

    Bolis, V.; Maggiorini, S.; Meda, L.; D'Acapito, F.; Palomino, G. Turnes; Bordiga, S.; Lamberti, C.

    2000-11-01

    The oxidation state of Cu species dispersed in a Cu-ZSM-5 zeolite obtained by a nonconventional gas-phase CuCl exchange, and nominally containing only Cu(I) species, was studied by x-ray photoelectron spectroscopy (XPS) and x-ray absorption near edge structure (XANES) analyses. The oxidation of Cu(I) species to Cu(II) by simple exposure to the atmosphere and subsequent reduction by thermal activation in vacuo was monitored. The quantitative and energetic aspects of the formation of carbonyl-like and amino-complexes at the metallic sites was studied by means of adsorption microcalorimetry. CO and NH3 were used as probe molecules in order to assess the coordinative unsaturation of the Cu(I) cations. Adsorption heats comprised in the 130-40 kJ mol-1 interval were obtained for the formation of both type of complexes. The perturbation induced on the Cu centers and/or on the zeolite matrix by the adsorption of the probe molecules was monitored by parallel experiments of XPS, IR, and XANES. A significant fraction of CO and NH3 molecules are irreversibly held on Cu(I) sites even after outgassing at room temperature (RT) at a final dynamic vacuum of 10-5 Torr. On the contrary, no evidence of Cu(I)/CO or of Cu(I)/NH3 complexes was observed by XPS, indicating that such adducts are totally destroyed upon outgassing at 10-9 Torr. This fact implies a reconsideration of what was previously considered as a "stable adduct." XPS allowed to reveal the existence of ammonia adsorbed on defective Al(III) species, and to explain the chemical nature of species formed at the earliest stages of NH3 dosage and characterized by a heat of adsorption as high as 180 kJ mol-1. By comparing the quantitative XPS and volumetric-calorimetric data it was inferred that a significant gradient of defects amount is present in the system. Finally, from the whole set of XPS measurements here reported and from parallel blank experiments on the ZSM-5 zeolite before Cu-exchange, a calibration scale for the N(1

  20. Exploring the interfacial structure of protein adsorbates and the kinetics of protein adsorption: an in situ high-energy X-ray reflectivity study.

    PubMed

    Evers, Florian; Shokuie, Kaveh; Paulus, Michael; Sternemann, Christian; Czeslik, Claus; Tolan, Metin

    2008-09-16

    The high energy X-ray reflectivity technique has been applied to study the interfacial structure of protein adsorbates and protein adsorption kinetics in situ. For this purpose, the adsorption of lysozyme at the hydrophilic silica-water interface has been chosen as a model system. The structure of adsorbed lysozyme layers was probed for various aqueous solution conditions. The effect of solution pH and lysozyme concentration on the interfacial structure was measured. Monolayer formation was observed for all cases except for the highest concentration. The adsorbed protein layers consist of adsorbed lysozyme molecules with side-on or end-on orientation. By means of time-dependent X-ray reflectivity scans, the time-evolution of adsorbed proteins was monitored as well. The results of this study demonstrate the capabilities of in situ X-ray reflectivity experiments on protein adsorbates. The great advantages of this method are the broad wave vector range available and the high time resolution.

  1. Exploring the interfacial structure of protein adsorbates and the kinetics of protein adsorption: an in situ high-energy X-ray reflectivity study.

    PubMed

    Evers, Florian; Shokuie, Kaveh; Paulus, Michael; Sternemann, Christian; Czeslik, Claus; Tolan, Metin

    2008-09-16

    The high energy X-ray reflectivity technique has been applied to study the interfacial structure of protein adsorbates and protein adsorption kinetics in situ. For this purpose, the adsorption of lysozyme at the hydrophilic silica-water interface has been chosen as a model system. The structure of adsorbed lysozyme layers was probed for various aqueous solution conditions. The effect of solution pH and lysozyme concentration on the interfacial structure was measured. Monolayer formation was observed for all cases except for the highest concentration. The adsorbed protein layers consist of adsorbed lysozyme molecules with side-on or end-on orientation. By means of time-dependent X-ray reflectivity scans, the time-evolution of adsorbed proteins was monitored as well. The results of this study demonstrate the capabilities of in situ X-ray reflectivity experiments on protein adsorbates. The great advantages of this method are the broad wave vector range available and the high time resolution. PMID:18715021

  2. X-ray photoelectron and Auger electron spectroscopic study of the adsorption of molecular iodine on uranium metal and uranium dioxide

    SciTech Connect

    Dillard, J.G.; Moers, H.; Klewe-Nebenius, H.; Kirch, G.; Pfennig, G.; Ache, H.J.

    1984-08-30

    The adsorption of molecular iodine on uranium metal and on uranium dioxide has been investigated at 25/sup 0/C. Clean surfaces were prepared in an ultrahigh vacuum apparatus and were characterized by X-ray photoelectron (XPS) and X-ray and electron-induced Auger electron spectroscopies (AES). Adsorption of I/sub 2/ was studied for exposures up to 100 langmuirs (1 langmuir = 10/sup -6/ torr s) on uranium metal and to 75 langmuirs on uranium dioxide. Above about 2-langmuir I/sub 2/ exposure on uranium, spectroscopic evidence is obtained to indicate the beginning of UI/sub 3/ formation. Saturation coverage for I/sub 2/ adsorption on uranium dioxide occurs at approximately 10-15 langmuirs. Analysis of the XPS and AES results as well as studies of spectra as a function of temperature lead to the conclusions that a dissociative chemisorption/reaction process occurs on uranium metal while nondissociative adsorption occurs on uranium dioxide. Variations in the iodine Auger kinetic energy and in the Auger parameter are interpreted in light of extra-atomic relaxation processes. 42 references, 10 figures, 1 table.

  3. Adsorption of dopamine on rutile TiO2 (110): a photoemission and near-edge X-ray absorption fine structure study.

    PubMed

    Jackman, Mark J; Syres, Karen L; Cant, David J H; Hardman, Samantha J O; Thomas, Andrew G

    2014-07-29

    Synchrotron radiation photoelectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) techniques have been used to study the adsorption of dopamine on a rutile TiO2 (110) single crystal. Photoemission results suggest that dopamine bonds through the oxygen molecules in a bidentate fashion. From the data, it is ambiguous whether the oxygens bond to the same 5-fold coordinated surface titanium atom or bridges across two, although based on the bonding of pyrocatechol on rutile TiO2 (110), it is likely that the dopamine bridges two titanium atoms. Using the searchlight effect, the carbon K-edge near-edge X-ray absorption fine structure NEXAFS spectra recorded for dopamine on rutile TiO2 (110) show the phenyl ring to be oriented at 78° ± 5° from the surface and twisted 11 ± 10° relative to the (001) direction.

  4. Adsorption of dopamine on rutile TiO2 (110): a photoemission and near-edge X-ray absorption fine structure study.

    PubMed

    Jackman, Mark J; Syres, Karen L; Cant, David J H; Hardman, Samantha J O; Thomas, Andrew G

    2014-07-29

    Synchrotron radiation photoelectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) techniques have been used to study the adsorption of dopamine on a rutile TiO2 (110) single crystal. Photoemission results suggest that dopamine bonds through the oxygen molecules in a bidentate fashion. From the data, it is ambiguous whether the oxygens bond to the same 5-fold coordinated surface titanium atom or bridges across two, although based on the bonding of pyrocatechol on rutile TiO2 (110), it is likely that the dopamine bridges two titanium atoms. Using the searchlight effect, the carbon K-edge near-edge X-ray absorption fine structure NEXAFS spectra recorded for dopamine on rutile TiO2 (110) show the phenyl ring to be oriented at 78° ± 5° from the surface and twisted 11 ± 10° relative to the (001) direction. PMID:25003716

  5. Effect of chlorine in clay-mineral specimens prepared on silver metal-membrane mounts for X-ray powder diffraction analysis

    USGS Publications Warehouse

    Poppe, L.J.; Commeau, J.A.; Pense, G.M.

    1989-01-01

    Silver metal-membrane filters are commonly used as substrates in the preparation of oriented clay-mineral specimens for X-ray powder diffraction (XRD). The silver metal-membrane filters, however, present some problems after heat treatment if either the filters or the samples contain significant amounts of chlorine. At elevated temperature, the chloride ions react with the silver substrate to form crystalline compounds. These compounds change the mass-absorption coefficient of the sample, reducing peak intensities and areas and, therefore, complicating the semiquantitative estimation of clay minerals. A simple procedure that eliminates most of the chloride from a sample and the silver metal-membrane substrate is presented here.

  6. Determination of tungsten in tantalum-tungsten alloy by X-ray fluorescence spectrometry using fusion, thin layer, and pressed powder pellet techniques

    NASA Astrophysics Data System (ADS)

    Tian, Lunfu; Zou, Deshuang; Dai, Yichun; Tang, Guangping

    2015-08-01

    A method is described for the X-ray fluorescence (XRF) determination of tungsten in tantalum-tungsten alloy over the range of 10.5%-13.5%. The sample was prepared by three methods, namely, borate fusion, filter paper disk, and pressed powder pellet, respectively. We compared the feature of the three methods of specimen preparation and found that filter paper disk method was the most suitable technique for specimen preparation. Furthermore, the results were compared with those given by inductively coupled plasma optical emission spectrometry (ICP-OES), and the relative standard deviation was less than 2%, which could meet the requirement of this application.

  7. In situ X-ray powder diffraction studies of the synthesis of graphene oxide and formation of reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Storm, Mie Møller; Johnsen, Rune E.; Norby, Poul

    2016-08-01

    Graphene oxide (GO) and reduced graphene oxide (rGO) are important materials in a wide range of fields. The modified Hummers methods, for synthesizing GO, and subsequent thermal reduction to rGO, are often employed for production of rGO. However, the mechanism behinds these syntheses methods are still unclear. We present an in situ X-ray diffraction study of the synthesis of GO and thermal reduction of GO. The X-ray diffraction revealed that the Hummers method includes an intercalation state and finally formation of additional crystalline material. The formation of GO is observed during both the intercalation and the crystallization stage. During thermal reduction of GO three stages were observed: GO, a disordered stage, and the rGO stage. The appearance of these stages depends on the heating ramp. The aim of this study is to provide deeper insight into the chemical and physical processes during the syntheses.

  8. Devitrification of Mechanically Alloyed Zr-Ti-Nb-Cu-Ni-Al Glassy Powders Studied by Time-Resolved X-ray Diffraction

    SciTech Connect

    Scudino, S.; Sordelet, D.J.; Eckert, J.

    2009-04-13

    The crystallization of mechanically alloyed Zr{sub 67}Ti{sub 6.14}Nb{sub 1.92}Cu{sub 10.67}Ni{sub 8.52}Al{sub 5.75} glassy powder is investigated by time-resolved X-ray diffraction. The powder displays a multi-step crystallization behavior characterized by the formation of a metastable nanoscale quasicrystalline phase during the first stage of the crystallization process. At higher temperatures, coinciding with the second crystallization event, the amorphous-to-quasicrystalline transformation is followed by the precipitation of the tetragonal Zr{sub 2}Cu phase (space group I4/mmm) and the tetragonal Zr{sub 2}Ni phase (space group I4/mcm). The transformations are gradual and the quasicrystals and the subsequent phases coexist over a temperature interval of about 25K.

  9. Direct observation of solid-phase adsorbate concentration profile in powdered activated carbon particle to elucidate mechanism of high adsorption capacity on super-powdered activated carbon.

    PubMed

    Ando, Naoya; Matsui, Yoshihiko; Matsushita, Taku; Ohno, Koichi

    2011-01-01

    Decreasing the particle size of powdered activated carbon (PAC) by pulverization increases its adsorption capacities for natural organic matter (NOM) and polystyrene sulfonate (PSS, which is used as a model adsorbate). A shell adsorption mechanism in which NOM and PSS molecules do not completely penetrate the adsorbent particle and instead preferentially adsorb near the outer surface of the particle has been proposed as an explanation for this adsorption capacity increase. In this report, we present direct evidence to support the shell adsorption mechanism. PAC particles containing adsorbed PSS were sectioned with a focused ion beam, and the solid-phase PSS concentration profiles of the particle cross-sections were directly observed by means of field emission-scanning electron microscopy/energy-dispersive X-ray spectrometry (FE-SEM/EDXS). X-ray emission from sulfur, an index of PSS concentration, was higher in the shell region than in the inner region of the particles. The X-ray emission profile observed by EDXS did not agree completely with the solid-phase PSS concentration profile predicted by shell adsorption model analysis of the PSS isotherm data, but the observed and predicted profiles were not inconsistent when the analytical errors were considered. These EDXS results provide the first direct evidence that PSS is adsorbed mainly in the vicinity of the external surface of the PAC particles, and thus the results support the proposition that the increase in NOM and PSS adsorption capacity with decreasing particle size is due to the increase in external surface area on which the molecules can be adsorbed. PMID:20851447

  10. Rietveld Analysis of X-ray Powder Diffraction Patterns as a Potential Tool for the Identification of Impact-deformed Carbonate Rocks

    SciTech Connect

    Huson, Sarah A.; Foit, Franklin F.; Watkinson, A. J.; Pope, Michael C.

    2009-11-01

    Previous X-ray powder diffraction (XRD) studies revealed that shock deformed carbonates and quartz have broader XRD patterns than those of unshocked samples. Entire XRD patterns, single peak profiles and Rietveld refined parameters of carbonate samples from the Sierra Madera impact crater, west Texas, unshocked equivalent samples from 95 miles north of the crater and the Mission Canyon Formation of southwest Montana and western Wyoming were used to evaluate the use of X-ray powder diffraction as a potential tool for distinguishing impact deformed rocks from unshocked and tectonically deformed rocks. At Sierra Madera dolostone and limestone samples were collected from the crater rim (lower shock intensity) and the central uplift (higher shock intensity). Unshocked equivalent dolostone samples were collected from well cores drilled outside of the impact crater. Carbonate rocks of the Mission Canyon Formation were sampled along a transect across the tectonic front of the Sevier and Laramide orogenic belts. Whereas calcite subjected to significant shock intensities at the Sierra Madera impact crater can be differentiated from tectonically deformed calcite from the Mission Canyon Formation using Rietveld refined peak profiles, weakly shocked calcite from the crater rim appears to be indistinguishable from the tectonically deformed calcite. In contrast, Rietveld analysis readily distinguishes shocked Sierra Madera dolomite from unshocked equivalent dolostone samples from outside the crater and tectonically deformed Mission Canyon Formation dolomite.

  11. Revealing the powdering methods of black makeup in Ancient Egypt by fitting microstructure based Fourier coefficients to the whole x-ray diffraction profiles of galena

    NASA Astrophysics Data System (ADS)

    Ungár, T.; Martinetto, P.; Ribárik, G.; Dooryhée, E.; Walter, Ph.; Anne, M.

    2002-02-01

    Galena (PbS) is a major ingredient in ancient Egyptian eye makeup. The microstructure of PbS in Egyptian cosmetic powders is used as a fingerprint and is matched with the microstructures produced artificially in geological galena minerals. The microstructure of PbS is determined by x-ray diffraction peak profile analysis in terms of dislocation density, crystallite size, and size distribution. High-resolution powder diffractograms were measured at the ESRF Grenoble synchrotron source with high resolution and high peak-to-background ratios. The Fourier coefficients of the first nine measured reflections of galena are fitted using physically based Fourier coefficients of strain and size functions. Strain anisotropy is accounted for by the dislocation model of the mean square strain. The x-ray data are supplemented by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs, and are compared with archæological documents. It enables us to describe the procedures of eye makeup manufacturing in the Middle and New Kingdoms of Egypt some 2000 years before Christ.

  12. Adsorption of basic dyes from aqueous solution onto pumice powder.

    PubMed

    Akbal, Feryal

    2005-06-15

    The adsorption of methylene blue and crystal violet on pumice powder samples of varying compositions was investigated using a batch adsorption technique. The effects of various experimental parameters, such as adsorbent dosage, initial dye concentration, and contact time, were also investigated. The extent of dye removal increased with decreased initial concentration of the dye and also increased with increased contact time and amount of adsorbent used. Adsorption data were modeled using the Freundlich adsorption isotherm. The adsorption kinetic of methylene blue and crystal violet could be described by the pseudo-second-order reaction model.

  13. Resonant anomalous x-ray reflectivity as a probe of ion adsorption at solid-liquid interfaces.

    SciTech Connect

    Fenter, P.; Park, C.; Nagy, K. L.; Sturchio, N. C.; Chemistry; Univ. of Illinois at Chicago

    2007-05-23

    We discuss new opportunities to understand processes at the solid-liquid interface using resonant anomalous X-ray reflectivity (RAXR). This approach is illustrated by determination of element-specific density profiles at mica surfaces in aqueous electrolyte solutions containing Rb{sup +} and Sr{sup 2+}. The total interfacial electron density profile is determined by specular reflectivity (i.e., reflected intensity vs. momentum transfer, q, at an energy, E, far from any characteristic absorption edge). RAXR spectra (i.e., intensity vs. E at fixed q) reveal element-specific ion distributions. Key differences in the interaction of Rb{sup +} and Sr{sup 2+} with mica are observed using resonant anomalous X-ray reflectivity: Rb{sup +} adsorbs in a partially hydrated state, but Sr{sup 2+} adsorbs in both fully and partially hydrated states.

  14. Adsorption and stability of malonic acid on rutile TiO2 (110), studied by near edge X-ray absorption fine structure and photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Syres, Karen L.; Thomas, Andrew G.; Graham, Darren M.; Spencer, Ben F.; Flavell, Wendy R.; Jackman, Mark J.; Dhanak, Vinod R.

    2014-08-01

    The adsorption of malonic acid on rutile TiO2 (110) has been studied using photoelectron spectroscopy and C K-edge, near edge X-ray fine structure spectroscopy (NEXAFS). Analysis of the O 1s and Ti 2p spectra suggest that the molecule adsorbs dissociatively in a doubly-bidentate adsorption geometry as malonate. The data are unable to distinguish between a chelating bonding mode with the backbone of the molecule lying along the [001] azimuth or a bridging geometry along the direction. Work carried out on a wiggler beamline suggests that the molecule is unstable under irradiation by high-flux synchrotron radiation from this type of insertion device.

  15. Low-temperature adsorption of H2S on Ni(001) studied by near-edge- and surface-extended-x-ray-absorption fine structure

    NASA Astrophysics Data System (ADS)

    McGrath, R.; MacDowell, A. A.; Hashizume, T.; Sette, F.; Citrin, P. H.

    1989-11-01

    The adsorption of H2S on Ni(001) has been studied with surface-extended x-ray-absorption fine structure and near-edge x-ray-absorption fine structure (NEXAFS) using the AT&T Bell Laboratories X15B beamline at the National Synchrotron Light Source. At 95 K and full saturation coverage, ~0.45 monolayer (ML) of S atoms in fourfold-hollow sites are produced, characteristic of room-temperature adsorption, accompanied by ~0.05 ML of oriented molecular H2S. Both these atomic and molecular chemisorbed species are buried under ~0.9 ML of disordered physisorbed H2S. No evidence for HS is found. Above 190 K the two molecular H2S phases desorb, leaving only dissociated S. These findings differ from previously reported interpretations of data obtained with high-resolution electron-energy-loss spectroscopy. They also exemplify the utility of NEXAFS for identifying and quantifying atomic and molecular surface species even when their difference involves only H and the two species coexist.

  16. Copper doped TiO2 nanoparticles characterized by X-ray absorption spectroscopy, total scattering, and powder diffraction – a benchmark structure–property study

    SciTech Connect

    Lock, Nina; Jensen, Ellen M. L.; Mi, Jianli; Mamakhel, Aref; Norén, Katarina; Qingbo, Meng; Iversen, Bo B.

    2013-01-01

    Metal functionalized nanoparticles potentially have improved properties e.g. in catalytic applications, but their precise structures are often very challenging to determine. Here we report a structural benchmark study based on tetragonal anatase TiO2 nanoparticles containing 0–2 wt% copper. The particles were synthesized by continuous flow synthesis under supercritical water–isopropanol conditions. Size determination using synchrotron PXRD, TEM, and X-ray total scattering reveals 5–7 nm monodisperse particles. The precise dopant structure and thermal stability of the highly crystalline powders were characterized by X-ray absorption spectroscopy and multi-temperature synchrotron PXRD (300–1000 K). The combined evidence reveals that copper is present as a dopant on the particle surfaces, most likely in an amorphous oxide or hydroxide shell. UV-VIS spectroscopy shows that copper presence at concentrations higher than 0.3 wt% lowers the band gap energy. The particles are unaffected by heating to 600 K, while growth and partial transformation to rutile TiO2 occur at higher temperatures. Anisotropic unit cell behavior of anatase is observed as a consequence of the particle growth (a decreases and c increases).

  17. Quadrupole lamp furnace for high temperature (up to 2050 K) synchrotron powder x-ray diffraction studies in air in reflection geometry.

    SciTech Connect

    Sarin, P.; Yoon, W.; Jurkschat, K.; Zschack, P.; Kriven, W. M.; Univ. of Illinois; Frederick-Seitz Materials Research Lab.

    2006-09-01

    A four-lamp thermal image furnace has been developed to conduct high temperature x-ray diffraction in reflection geometry on oxide ceramic powder samples in air at temperatures {le} 2050 K using synchrotron radiation. A refractory crucible made of Pt20%Rh alloy was used as a specimen holder. A material with well characterized lattice expansion properties was used as an internal crystallographic thermometer to determine the specimen temperature and displacement. The performance of the apparatus was verified by measurement of the thermal expansion properties of CeO{sub 2}, MgO, and Pt which were found to be within {+-} 3% of the acceptable values. The advantages, limitations, and important considerations of the instrument developed are discussed.

  18. Quadrupole lamp furnace for high temperature (up to 2050 K) synchrotron powder x-ray diffraction studies in air in reflection geometry

    SciTech Connect

    Sarin, P.; Yoon, W.; Jurkschat, K.; Zschack, P.; Kriven, W. M.

    2006-09-15

    A four-lamp thermal image furnace has been developed to conduct high temperature x-ray diffraction in reflection geometry on oxide ceramic powder samples in air at temperatures {<=}2050 K using synchrotron radiation. A refractory crucible made of Pt20%Rh alloy was used as a specimen holder. A material with well characterized lattice expansion properties was used as an internal crystallographic thermometer to determine the specimen temperature and displacement. The performance of the apparatus was verified by measurement of the thermal expansion properties of CeO{sub 2}, MgO, and Pt which were found to be within {+-}3% of the acceptable values. The advantages, limitations, and important considerations of the instrument developed are discussed.

  19. Structure and electronic properties of Dy@C 82 studied by UV-VIS absorption, X-ray powder diffraction and XAFS

    NASA Astrophysics Data System (ADS)

    Iida, S.; Kubozono, Y.; Slovokhotov, Y.; Takabayashi, Y.; Kanbara, T.; Fukunaga, T.; Fujiki, S.; Emura, S.; Kashino, S.

    2001-04-01

    Two isomers of Dy@C 82 were separated by high performance liquid chromatography (HPLC), and their UV-VIS absorption spectra were measured to characterize these isomers. The crystalline powder of Dy@C 82 was obtained by removing the solvent (toluene) at 250°C under vacuum. The X-ray diffraction pattern can be indexed with fcc crystal lattice, as that in La@C 82. The lattice constant a at 298 K, 15.86(1) Å, is close to that of La@C 82, 15.78 Å. The distances between Dy and the first and second nearest C atoms are determined to be 2.52(2) and 2.86(2) Å, respectively, on the basis of Dy L III-edge EXAFS. The XANES shows that the valence of the Dy atom in Dy@C 82 is +3.

  20. Crystal Structures of the Trifluoromethyl Sulfonates M(SO3CF3)2 (M = Mg, Ca, Ba, Zn, Cu) from Synchrotron X-ray Powder Diffraction Data

    SciTech Connect

    Dinnebier,R.; Sofina, N.; Hildebrandt, L.; Jansen, M.

    2006-01-01

    The crystal structures of divalent metal salts of trifluoromethyl sulfonic acid ('trifluoromethyl sulfonates') M(SO{sub 3}CF{sub 3}){sub 2} (M = Mg, Ca, Ba, Zn, Cu) were determined from high-resolution X-ray powder diffraction data. Magnesium, calcium and zinc trifluoromethyl sulfonate crystallize in the rhombohedral space group R{bar 3}. Barium trifluoromethyl sulfonate crystallizes in the monoclinic space group I2/a(C2/c) and copper trifluoromethyl sulfonate crystallizes in the triclinic group P{bar 1}. Within the crystal structures the trifluoromethyl sulfonate anions are arranged in double layers with the apolar CF{sub 3} groups pointing towards each other. The cations are located next to the SO{sub 3} groups. The symmetry relations between the different crystal structures have been analyzed.

  1. Lithium cobalt(II) pyrophosphate, Li[subscript 1.86]CoP[subscript 2]O[subscript 7], from synchrotron X-ray powder data

    SciTech Connect

    Zhou, Hui; Upreti, Shailesh; Chernova, Natasha A.; Whittingham, M.Stanley

    2015-10-15

    Structure refinement of high-resolution X-ray powder diffraction data of the title compound gave the composition Li{sub 1.865}CoP{sub 2}O{sub 7}, which is also verified by the ICP measurement. Two Co sites exist in the structure: one is a CoO{sub 5} square pyramid and the other is a CoO{sub 6} octahedron. They share edges and are further interconnected through P{sub 2}O{sub 7} groups, forming a three-dimensional framework, which exhibits different kinds of intersecting tunnels containing Li cations and could be of great interest in Li ion battery chemistry. The structure also exhibits cation disorder with 13.5% Co residing at the lithium (Li1) site. Co seems to have an average oxidation state of 2.135, as obtained from the strutural stochiometry that closely supports the magnetic susceptibility findings.

  2. Vacancy-induced nanoscale phase separation in KxFe2–ySe₂ single crystals evidenced by Raman scattering and powder x-ray diffraction

    DOE PAGES

    Lazarević, N.; Abeykoon, M.; Stephens, P. W.; Lei, Hechang; Bozin, E. S.; Petrovic, C.; Popović, Z. V.

    2012-08-06

    Polarized Raman scattering spectra of KxFe2–ySe₂ were analyzed in terms of peculiarities of both I4/m and I4/mmm space group symmetries. The presence of the Raman active modes from both space group symmetries (16 Raman-active modes of the I4/m phase and two Raman-active modes of the I4/mmm phase) confirmed the existence of two crystallographic domains with different space group symmetry in a KxFe2–ySe₂ sample. High-resolution synchrotron powder x-ray diffraction structural refinement of the same sample confirmed the two-phase description, and determined the atomic positions and occupancies for both domains.

  3. Functional biocompatible magnetite-cellulose nanocomposite fibrous networks: Characterization by fourier transformed infrared spectroscopy, X-ray powder diffraction and field emission scanning electron microscopy analysis

    NASA Astrophysics Data System (ADS)

    Habibi, Neda

    2015-02-01

    The preparation and characterization of functional biocompatible magnetite-cellulose nano-composite fibrous material is described. Magnetite-cellulose nano-composite was prepared by a combination of the solution-based formation of magnetic nano-particles and subsequent coating with amino celluloses. Characterization was accomplished using X-ray powder diffraction (XRD), fourier transformed infrared (FTIR) and field emission scanning electron microscopy (FESEM) analysis. The peaks of Fe3O4 in the XRD pattern of nanocomposite confirm existence of the nanoparticles in the amino cellulose matrix. Magnetite-cellulose particles exhibit an average diameter of roughly 33 nm as demonstrated by field emission scanning electron microscopy. Magnetite nanoparticles were irregular spheres dispersed in the cellulose matrix. The vibration corresponding to the Nsbnd CH3 functional group about 2850 cm-1 is assigned in the FTIR spectra. Functionalized magnetite-cellulose nano-composite polymers have a potential range of application as targeted drug delivery system in biomedical field.

  4. Phase Transitions in the Ruddlesden-Popper Phase Li2CaTa2O7: X-ray and Neutron Powder Thermodiffraction, TEM, Raman, and SHG Experiments.

    PubMed

    Galven, Cyrille; Mounier, Denis; Bouchevreau, Boris; Suard, Emmanuelle; Bulou, Alain; Crosnier-Lopez, Marie-Pierre; Le Berre, Françoise

    2016-03-01

    The structure of the Ruddlesden-Popper layered perovskite Li2CaTa2O7, known for its high photocatalytic water activity since its discovery in 2008, is reinvestigated. This oxide has been characterized by powder X-ray and neutron thermodiffraction, TEM, second harmonic generation (SHG), and Raman experiments on powders and single crystals. It is shown that it undergoes two structural phase transitions (i) around 220 °C, mainly characterized by the progressive emergence of SHG signal at low temperatures, and (ii) at 660 °C, mainly characterized by changes of the temperature behavior of lattice parameters and by the emergence of Raman signals that linearly increase on decreasing temperature. It is shown by powder neutron diffraction profile refinements at RT, 400, and 800 °C that the space groups of the successive phases of Li2CaTa2O7 are the acentric Pna21 (RT ≤ T ≤ 220 °C), Pnma (220 °C ≤ T ≤ 660 °C), and Cmcm (T ≥ 660 °C). A soft mode associated with the transition to the highest symmetry for this structural arrangement (I4/mmm) is also found in the Raman spectra. All these transitions appear continuous: the high temperature ones can be attributed to progressive vanishings of the octahedra tiltings (displacives) while the transition in the vicinity of 220 °C from Pna21 to Pnma exhibits order-disorder character.

  5. Calorimetry investigations of milled α-tricalcium phosphate (α-TCP) powders to determine the formation enthalpies of α-TCP and X-ray amorphous tricalcium phosphate.

    PubMed

    Hurle, Katrin; Neubauer, Juergen; Bohner, Marc; Doebelin, Nicola; Goetz-Neunhoeffer, Friedlinde

    2015-09-01

    One α-tricalcium phosphate (α-TCP) powder was either calcined at 500°C to obtain fully crystalline α-TCP or milled for different durations to obtain α-TCP powders containing various amounts of X-ray amorphous tricalcium phosphate (ATCP). These powders containing between 0 and 71wt.% ATCP and up to 2.0±0.1wt.% β-TCP as minor phase were then hydrated in 0.1M Na2HPO4 aqueous solution and the resulting heat flows were measured by isothermal calorimetry. Additionally, the evolution of the phase composition during hydration was determined by in situ XRD combined with the G-factor method, an external standard method which facilitates the indirect quantification of amorphous phases. Maximum ATCP hydration was reached after about 1h, while that of crystalline α-TCP hydration occurred between 4 and 11h, depending on the ATCP content. An enthalpy of formation of -4065±6kJ/mol (T=23°C) was calculated for ATCP (Ca3(PO4)2), while for crystalline α-TCP (α-Ca3(PO4)2) a value of -4113±6kJ/mol (T=23°C) was determined.

  6. Rb+ adsorption at the quartz(101)-aqueous interface: comparison of resonant anomalous x-ray reflectivity with ab initio calculations

    SciTech Connect

    Bellucci, Francesco; Lee, Sang Soo; Kubicki, James D.; Bandura, Andrei V.; Zhang, Zhan; Wesolowski, David J.; Fenter, Paul

    2015-01-29

    We study adsorption of Rb+ to the quartz(101)–aqueous interface at room temperature with specular X-ray reflectivity, resonant anomalous X-ray reflectivity, and density functional theory. The interfacial water structures observed in deionized water and 10 mM RbCl solution at pH 9.8 were similar, having a first water layer at height of 1.7 ± 0.1 Å above the quartz surface and a second layer at 4.8 ± 0.1 Å and 3.9 ± 0.8 Å for the water and RbCl solutions, respectively. The adsorbed Rb+ distribution is broad and consists of presumed inner-sphere (IS) and outer-sphere (OS) complexes at heights of 1.8 ± 0.1 and 6.4 ± 1.0 Å, respectively. Projector-augmented planewave density functional theory (DFT) calculations of potential configurations for neutral and negatively charged quartz(101) surfaces at pH 7 and 12, respectively, reveal a water structure in agreement with experimental results. These DFT calculations also show differences in adsorbed speciation of Rb+ between these two conditions. At pH 7, the lowest energy structure shows that Rb+ adsorbs dominantly as an IS complex, whereas at pH 12 IS and OS complexes have equivalent energies. The DFT results at pH 12 are generally consistent with the two site Rb distribution observed from the X-ray data at pH 9.8, albeit with some differences that are discussed. In conclusion, surface charge estimated on the basis of the measured total Rb+ coverage was -0.11 C/m2, in good agreement with the range of the surface charge magnitudes reported in the literature.

  7. Arsenic adsorption by iron-aluminium hydroxide coated onto macroporous supports: Insights from X-ray absorption spectroscopy and comparison with granular ferric hydroxides.

    PubMed

    Suresh Kumar, Prashanth; Flores, Roxana Quiroga; Sjöstedt, Carin; Önnby, Linda

    2016-01-25

    This paper evaluates the arsenic adsorption characteristics of a macroporous polymer coated with coprecipitated iron-aluminium hydroxides (MHCMP). The MHCMP adsorbent-composite fits best with a pseudo-second order model for As(III) and a pseudo-first order kinetic model for As(V). The MHCMP shows a maximum adsorption capacity of 82.3 and 49.6 mg As/g adsorbent for As(III) and As(V) ions respectively, and adsorption followed the Langmuir model. Extended X-ray absorption fine structure showed that binding of As(III) ions were confirmed to take place on the iron hydroxides coated on the MHCMP, whereas for As(V) ions the binding specificity could not be attributed to one particular metal hydroxide. As(III) formed a bidentate mononuclear complex with Fe sites, whereas As(V) indicated on a bidentate binuclear complex with Al sites or monodentate with Fe sites on the adsorbent. The column experiments were run in a well water spiked with a low concentration of As(III) (100 μg/L) and a commercially available adsorbent (GEH(®)102) based on granular iron-hydroxide was used for comparison. It was found that the MHCMP was able to treat 7 times more volume of well water as compared to GEH(®)102, maintaining the threshold concentration of less than 10 μg As/L, indicating that the MHCMP is a superior adsorbent.

  8. Interactions between natural organic matter, sulfur, arsenic and iron oxides in re-oxidation compounds within riparian wetlands: nanoSIMS and X-ray adsorption spectroscopy evidences.

    PubMed

    Al-Sid-Cheikh, Maya; Pédrot, Mathieu; Dia, Aline; Guenet, Hélène; Vantelon, Delphine; Davranche, Mélanie; Gruau, Gérard; Delhaye, Thomas

    2015-05-15

    Arsenic (As) is a toxic and ubiquitous element which can be responsible for severe health problems. Recently, Nano-scale Secondary Ions Mass Spectrometry (nanoSIMS) analysis has been used to map organomineral assemblages. Here, we present a method adapted from Belzile et al. (1989) to collect freshly precipitated compounds of the re-oxidation period in a natural wetland environment using a polytetrafluoroethylene (PTFE) sheet scavenger. This method provides information on the bulk samples and on the specific interactions between metals (i.e. As) and the natural organic matter (NOM). Our method allows producing nanoSIMS imaging on natural colloid precipitates, including (75)As(-), (56)Fe(16)O(-), sulfur ((32)S(-)) and organic matter ((12)C(14)N) and to measure X-ray adsorption of sulfur (S) K-edge. A first statistical treatment on the nanoSIMS images highlights two main colocalizations: (1) (12)C(14)N(-), (32)S(-), (56)Fe(16)O(-) and (75)As(-), and (2) (12)C(14)N(-), (32)S(-) and (75)As(-). Principal component analyses (PCAs) support the importance of sulfur in the two main colocalizations firstly evidenced. The first component explains 70% of the variance in the distribution of the elements and is highly correlated with the presence of (32)S(-). The second component explains 20% of the variance and is highly correlated with the presence of (12)C(14)N(-). The X-ray adsorption near edge spectroscopy (XANES) on sulfur speciation provides a quantification of the organic (55%) and inorganic (45%) sulfur compositions. The co-existence of reduced and oxidized S forms might be attributed to a slow NOM kinetic oxidation process. Thus, a direct interaction between As and NOM through sulfur groups might be possible.

  9. Characterization of the Adsorption of Nucleic Acid Bases onto Ferrihydrite via Fourier Transform Infrared and Surface-Enhanced Raman Spectroscopy and X-ray Diffractometry.

    PubMed

    Canhisares-Filho, José E; Carneiro, Cristine E A; de Santana, Henrique; Urbano, Alexandre; da Costa, Antonio C S; Zaia, Cássia T B V; Zaia, Dimas A M

    2015-09-01

    Minerals could have played an important role in concentration, protection, and polymerization of biomolecules. Although iron is the fourth most abundant element in Earth's crust, there are few works in the literature that describe the use of iron oxide-hydroxide in prebiotic chemistry experiments. In the present work, the interaction of adenine, thymine, and uracil with ferrihydrite was studied under conditions that resemble those of prebiotic Earth. At acidic pH, anions in artificial seawater decreased the pH at the point of zero charge (pHpzc) of ferrihydrite; and at basic pH, cations increased the pHpzc. The adsorption of nucleic acid bases onto ferrihydrite followed the order adenine > uracil > thymine. Adenine adsorption peaked at neutral pH; however, for thymine and uracil, adsorption increased with increasing pH. Electrostatic interactions did not appear to play an important role on the adsorption of nucleic acid bases onto ferrihydrite. Adenine adsorption onto ferrihydrite was higher in distilled water compared to artificial seawater. After ferrihydrite was mixed with artificial seawaters or nucleic acid bases, X-ray diffractograms and Fourier transform infrared spectra did not show any change. Surface-enhanced Raman spectroscopy showed that the interaction of adenine with ferrihydrite was not pH-dependent. In contrast, the interactions of thymine and uracil with ferrihydrite were pH-dependent such that, at basic pH, thymine and uracil lay flat on the surface of ferrihydrite, and at acidic pH, thymine and uracil were perpendicular to the surface. Ferrihydrite adsorbed much more adenine than thymine; thus adenine would have been better protected against degradation by hydrolysis or UV radiation on prebiotic Earth. PMID:26393397

  10. Characterization of the Adsorption of Nucleic Acid Bases onto Ferrihydrite via Fourier Transform Infrared and Surface-Enhanced Raman Spectroscopy and X-ray Diffractometry.

    PubMed

    Canhisares-Filho, José E; Carneiro, Cristine E A; de Santana, Henrique; Urbano, Alexandre; da Costa, Antonio C S; Zaia, Cássia T B V; Zaia, Dimas A M

    2015-09-01

    Minerals could have played an important role in concentration, protection, and polymerization of biomolecules. Although iron is the fourth most abundant element in Earth's crust, there are few works in the literature that describe the use of iron oxide-hydroxide in prebiotic chemistry experiments. In the present work, the interaction of adenine, thymine, and uracil with ferrihydrite was studied under conditions that resemble those of prebiotic Earth. At acidic pH, anions in artificial seawater decreased the pH at the point of zero charge (pHpzc) of ferrihydrite; and at basic pH, cations increased the pHpzc. The adsorption of nucleic acid bases onto ferrihydrite followed the order adenine > uracil > thymine. Adenine adsorption peaked at neutral pH; however, for thymine and uracil, adsorption increased with increasing pH. Electrostatic interactions did not appear to play an important role on the adsorption of nucleic acid bases onto ferrihydrite. Adenine adsorption onto ferrihydrite was higher in distilled water compared to artificial seawater. After ferrihydrite was mixed with artificial seawaters or nucleic acid bases, X-ray diffractograms and Fourier transform infrared spectra did not show any change. Surface-enhanced Raman spectroscopy showed that the interaction of adenine with ferrihydrite was not pH-dependent. In contrast, the interactions of thymine and uracil with ferrihydrite were pH-dependent such that, at basic pH, thymine and uracil lay flat on the surface of ferrihydrite, and at acidic pH, thymine and uracil were perpendicular to the surface. Ferrihydrite adsorbed much more adenine than thymine; thus adenine would have been better protected against degradation by hydrolysis or UV radiation on prebiotic Earth.

  11. High temperature phase stability in Li0.12Na0.88NbO3: A combined powder X-ray and neutron diffraction study

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Krishna, P. S. R.; Shinde, A. B.; Jayakrishnan, V. B.; Mittal, R.; Sastry, P. U.; Chaplot, S. L.

    2015-09-01

    The phase stabilities of ecofriendly piezoelectric material of lithium doped sodium niobate for composition Li0.12Na0.88NbO3 (LNN12) have been investigated by a combination of powder X-ray and neutron diffraction techniques in the temperature range of 300-1100 K. We observed interesting changes with appearance or disappearance of the super-lattice reflections in the powder diffraction patterns. Unambiguous experimental evidence is shown for coexistence of paraelectric and ferroelectric orthorhombic phases in the temperature range of 525 K to 675 K. We identified the correct crystal structure of LNN12 with temperature and correlated it with observed anomaly in the physical properties. Identification of crystal structure also helps in the mode assignments in Raman and infrared spectroscopies. We argued that application of chemical pressure as a result of Li substitution in NaNbO3 matrix favors the freezing of zone centre phonons in contrast to the freezing of zone boundary phonons in pure NaNbO3 with the variation of temperature.

  12. Kinetics of adsorption with granular, powdered, and fibrous activated carbon

    SciTech Connect

    Shmidt, J.L.; Pimenov, A.V.; Lieberman, A.I.; Cheh, H.Y.

    1997-08-01

    The properties of three different types of activated carbon, fibrous, powdered, and granular, were investigated theoretically and experimentally. The adsorption rate of the activated carbon fiber was found to be two orders of magnitude higher than that of the granular activated carbon, and one order of magnitude higher than that of the powdered activated carbon. Diffusion coefficients of methylene blue in the fibrous, powdered, and granular activated carbons were determined experimentally. A new method for estimating the meso- and macropore surface areas in these carbons was proposed.

  13. Joint x-ray

    MedlinePlus

    X-ray - joint; Arthrography; Arthrogram ... x-ray technologist will help you position the joint to be x-rayed on the table. Once in place, pictures are taken. The joint may be moved into other positions for more ...

  14. Chest X-Ray

    MedlinePlus

    ... by: Image/Video Gallery Your radiologist explains chest x-ray. Transcript Welcome to Radiology Info dot org! Hello, ... you about chest radiography also known as chest x-rays. Chest x-rays are the most commonly performed ...

  15. Cosmic x ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, Dan; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1991-01-01

    The annual progress report on Cosmic X Ray Physics for the period 1 Jan. to 31 Dec. 1990 is presented. Topics studied include: soft x ray background, new sounding rocket payload: x ray calorimeter, and theoretical studies.

  16. Cosmic x ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, Dan; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1990-01-01

    The annual progress report on Cosmic X Ray Physics is presented. Topics studied include: the soft x ray background, proportional counter and filter calibrations, the new sounding rocket payload: X Ray Calorimeter, and theoretical studies.

  17. CHARACTERIZATION OF THE LOCAL TITANIUM ENVIRONMENT IN DOPED SODIUM ALUMINUM HYDRIDE USING X-RAY ADSORPTION SPECTROSCOPY.

    SciTech Connect

    GRAETZ, J.; IGNATOV, A. YU; TYSON, T.A.; REILLY, J.J.; JOHNSON, J.

    2004-11-30

    Ti K-edge x-ray absorption spectroscopy was used to explore the local titanium environment and valence in 2-4 mol% Ti-doped sodium alanate. An estimate of the oxidation state of the dopant, based upon known standards, revealed a zero-valent titanium atom. An analysis of the near-edge and extended fine structures indicates that the Ti does not enter substitutional or interstitial sites in the NaAlH{sub 4} lattice. Rather, the Ti is located on/near the surface and is coordinated by 10.2 {+-} 1 aluminum atoms with an interatomic distance of 2.82 {+-} 0.01 {angstrom}, similar to that of TiAl{sub 3}. The Fourier transformed EXAFS spectra reveals a lack of long-range order around the Ti dopant indicating that the Ti forms nano-clusters of TiAl{sub 3}. The similarity of the spectra in the hydrided and dehydrided samples suggests that the local Ti environment is nearly invariant during hydrogen cycling.

  18. 5-Arylidene derivatives of Meldrum's acid: Synthesis, structural characterization using single crystal and powder crystal X-ray diffraction, and electronic properties

    NASA Astrophysics Data System (ADS)

    Dey, Tanusri; Ghosh, Soumen; Ghosh, Somnath; Mukherjee, Alok Kumar

    2015-07-01

    Four 5-arylidene derivatives of Meldrum's acid, 5-(4-chlorobenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (2), 5-(3-hydroxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (3), 5-(3,4-dimethoxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (4) and 5-(2,4-dimethoxy benzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (5) have been synthesized and their crystal structures have been determined using single crystal X-ray diffractometry for 2, 4 and 5 and X-ray powder diffraction for 3. The nature of intermolecular interactions in 2-5 has been analyzed through Hirshfeld surfaces and 2D fingerprint plots. The DFT optimized molecular geometries in 2-5 agree closely with those obtained from the crystallographic studies. The crystal packing in 2-5 exhibits an interplay of Osbnd H⋯O, Csbnd H⋯O, Csbnd H⋯Cl and Csbnd H⋯π (arene) hydrogen bonds and π⋯π interactions, which assemble molecules into three-dimensional architecture in 2, 3 and 5 and two-dimensional framework in 4. The Hirshfeld surface analyses of 2-5, Meldrum's acid (1) and a few related 5-arylidene derivatives of Meldrum's acid retrieved from the Cambridge Structural Database (CSD) indicate that about 85% of the Hirshfeld surface area (72% in 2 where H⋯Cl contribution is about 13%) in this class of compounds are due to H⋯H, O⋯H and C⋯H contacts. The HOMO-LUMO energy gap (>2.2 eV) in 2-5 indicates a significant degree of internal charge transfer within the molecule.

  19. Structural and Thermal Characterization of Zolpidem Hemitartrate Hemihydrate (Form E) and Its Decomposition Products by Laboratory X-Ray Powder Diffraction

    SciTech Connect

    Halasz, I.; Dinnebier, R

    2010-01-01

    The crystal structure of zolpidem hemitartrate hemihydrate (I, Form E) has been solved from high-resolution laboratory powder diffraction data. It crystallizes in the orthorhombic P2{sub 1}2{sub 1}2{sub 1} space group with a = 22.4664(6) {angstrom}, b = 26.0420(7) {angstrom}, and c = 7.4391(1) {angstrom}. Protonation of zolpidem molecules could not be unambiguously determined. Thermal stability of Form E has been investigated by TG-DTA and in situ by temperature resolved X-ray powder diffraction. Water loss occurs between 50 C {le} t {le} 100 C while structure decomposition commences at approximately 120 C yielding zolpidem tartrate (II) and pure zolpidem base (III) in approximately equimolar amounts. Crystal structures of II and III have been solved simultaneously from a single powder pattern of thermally decomposed I. Zolpidem tartrate crystallizes in the orthorhombic P2{sub 1}2{sub 1}2{sub 1} space group with a = 19.9278(8) {angstrom}, b = 15.1345(8) {angstrom}, and c = 7.6246(2) {angstrom} (at 140 C). Zolpidem base crystallizes in the orthorhombic Pcab space group with a = 9.9296(4) {angstrom}, b = 18.4412(9) {angstrom}, and c = 18.6807(9) {angstrom} (at 140 C). In the reported crystal structures zolpidem molecules form stacks through {pi}-{pi} interaction or dipole-dipole interactions while tartrate moieties, if present, form hydrogen bonded chains. Water molecule in I forms a hydrogen bond to the imidazole nitrogen atom of the zolpidem molecule. Free space in the crystal structure of I could allow for the additional water molecules and thus a variable water content.

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

    PubMed

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

    2016-01-01

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

  1. In situ SERS and X-ray photoelectron spectroscopy studies on the pH-dependant adsorption of anthraquinone-2-carboxylic acid on silver electrode

    NASA Astrophysics Data System (ADS)

    Li, Dan; Jia, Shaojie; Fodjo, Essy Kouadio; Xu, Hu; Wang, Yuhong; Deng, Wei

    2016-03-01

    In this study, in situ surface-enhanced Raman scattering (SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) are used to investigate the redox reaction and adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on an Ag electrode at different pH values. The obtained results indicate that AQ-2-COOH is adsorbed tilted on the Ag electrode through O-atom of ring carbonyl in a potential range from -0.3 to -0.5 V vs. SCE, but the orientation turns to more tilted orientation with both O-atom of the ring carbonyl and carboxylate group in positive potential region for pH 6.0 and 7.4. However, at pH 10.0, the orientation adopts tilted conformation constantly on the Ag electrode with both O-atom of the anthraquinone ring and carboxylate group in the potential range from -0.3 to -0.5 V vs. SCE or at positive potentials. Moreover, the adsorption behavior of AQ-2-COOH has been further confirmed by AR-XPS on the Ag surface. Proposed reasons for the observed changes in orientation are presented.

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  4. Single-crystal and humidity-controlled powder diffraction study of the breathing effect in a metal-organic framework upon water adsorption/desorption.

    PubMed

    Aríñez-Soriano, Javier; Albalad, Jorge; Vila-Parrondo, Christian; Pérez-Carvajal, Javier; Rodríguez-Hermida, Sabina; Cabeza, Aurelio; Juanhuix, Jordi; Imaz, Inhar; Maspoch, Daniel

    2016-05-26

    Herein we report a study on water adsorption/desorption-triggered single-crystal to single-crystal transformations in a MOF, by single-crystal and humidity-controlled powder X-ray diffraction and water-sorption measurements. We identified a gate-opening effect at a relative humidity of 85% upon water adsorption, and a gate-closure effect at a relative humidity of 55 to 77% upon water desorption. This reversible breathing effect between the "open" and the "closed" structures of the MOF involves the cleavage and formation of several coordination bonds.

  5. Th uptake on montmorillonite: a powder and polarized extended X-ray absorption fine structure (EXAFS) study.

    PubMed

    Dähn, Rainer; Scheidegger, André M; Manceau, Alain; Curti, Enzo; Baeyens, Bart; Bradbury, Michael H; Chateigner, Daniel

    2002-05-01

    The uptake process of Th(IV) onto montmorillonite was studied using powder and polarized-EXAFS (P-EXAFS) spectroscopy. Sorption samples were prepared in 0.1 M NaClO(4) solutions either undersaturated (pH 2 and 3, [Th](initial): 2.7x10(-6) to 4x10(-4) M) or supersatured (pH 5, [Th](initial): 4.3x10(-5) to 4x10(-4) M) with respect to amorphous ThO(2). Th loading varied between 1-157 micromol/g at pH 3 and 14-166 micromol/g at pH 5 and equaled 41 micromol/g at pH 2. At pH 5 and high surface loading the EXAFS spectrum resembled that of amorphous Th(OH)(4), suggesting the precipitation of a Th hydrous hydroxide. At low and intermediate surface coverage two O coordination shells at approximately 2.24 and approximately 2.48 A, and one Si shell at 3.81-3.88 A, were systematically observed regardless of pH. The formation of Th nucleation products and Th-Si solution complexes and the sorption of Th on a silica precipitate were excluded from the EXAFS spectra analysis and solution chemistry. In these conditions, Th was shown to bond the montmorillonite surface by sharing double corners with Si tetrahedra. This structural interpretation is consistent with surface coverage calculations which showed that the edge sites were saturated in the two highest concentrated samples (34 and 157 micromol/g) at pH 3.

  6. Chest x-ray

    MedlinePlus

    Chest radiography; Serial chest x-ray; X-ray - chest ... You stand in front of the x-ray machine. You will be told to hold your breath when the x-ray is taken. Two images are usually taken. You will ...

  7. The use of net analyte signal orthogonalization in the separation of multi-component diffraction patterns obtained from X-ray powder diffraction of intact compacts.

    PubMed

    Moore, Michael D; Cogdill, Robert P; Short, Steven M; Hair, Colleen R; Wildfong, Peter L D

    2008-06-01

    X-ray powder diffraction (XRPD) analysis of intact multi-component consolidated mixtures has significant potential owing to the ability to non-destructively quantify and discriminate between solid phases in composite bodies with minimal sample preparation. There are, however, limitations to the quantitative power using traditional univariate methods on diffraction data containing features from all components in the system. The ability to separate multi-component diffraction data into patterns representing single constituents allows both composition as well as physical phenomena associated with the individual components of complex systems to be probed. Intact, four-component compacts, consisting of two crystalline and two amorphous constituents were analyzed using XRPD configured in both traditional Bragg-Brentano reflectance geometry and parallel-beam transmission geometry. Two empirical, model-based methods consisting of a multiple step net analyte signal (NAS) orthogonalization are presented as ways to separate multi-component XRPD patterns into single constituent patterns. Multivariate figures of merit (FOM) were calculated for each of the isolated constituents to compare method-specific parameters such as sensitivity, selectivity, and signal-to-noise, enabling quantitative comparisons between the two modes of XRPD analysis. PMID:18294800

  8. Early age hydration and pozzolanic reaction in natural zeolite blended cements: Reaction kinetics and products by in situ synchrotron X-ray powder diffraction

    SciTech Connect

    Snellings, R.; Mertens, G.; Cizer, O.; Elsen, J.

    2010-12-15

    The in situ early-age hydration and pozzolanic reaction in cements blended with natural zeolites were investigated by time-resolved synchrotron X-ray powder diffraction with Rietveld quantitative phase analysis. Chabazite and Na-, K-, and Ca-exchanged clinoptilolite materials were mixed with Portland cement in a 3:7 weight ratio and hydrated in situ at 40 {sup o}C. The evolution of phase contents showed that the addition of natural zeolites accelerates the onset of C{sub 3}S hydration and precipitation of CH and AFt. Kinetic analysis of the consumption of C{sub 3}S indicates that the enveloping C-S-H layer is thinner and/or less dense in the presence of alkali-exchanged clinoptilolite pozzolans. The zeolite pozzolanic activity is interpreted to depend on the zeolite exchangeable cation content and on the crystallinity. The addition of natural zeolites alters the structural evolution of the C-S-H product. Longer silicate chains and a lower C/S ratio are deduced from the evolution of the C-S-H b-cell parameter.

  9. Quantitative study of solid-state acid-base reactions between polymorphs of flufenamic acid and magnesium oxide using X-ray powder diffraction.

    PubMed

    Chen, Xiaoming; Stowell, Joseph G; Morris, Kenneth R; Byrn, Stephen R

    2010-03-11

    The purpose of this study is to investigate solid-state acid-base reactions between polymorphs of flufenamic acid (FFA) and magnesium oxide (MgO) using X-ray powder diffraction (XRPD). Polymorphs of FFA were blended with MgO and stored under conditions of 96.5% RH and 89% RH at 40 degrees C. The disappearance of FFA and production of magnesium flufenamate were monitored by XRPD. It was observed that the reactions between FFA and MgO proceeded following the Jander equation. Form I of FFA is more reactive with MgO than Form III. Differential accessibility of reactive groups is hypothesized as one of the reasons that Form I is more reactive than Form III. It was noted that the reaction between FFA and MgO could be mitigated by adding another acidic excipient such as polyacrylic acid to prevent the acid-base reaction with FFA. The effectiveness of polyacrylic acid was impacted by the mixing order of the tertiary mixture. Mixing polyacrylic acid and MgO first provided the most significant protection. In conclusion, solid-state acid-base reactions could be investigated using XRPD. Different forms may have distinct reactivity. Acid-base reactions in the solid state could be mitigated through the addition of another "shielding" excipient.

  10. Crystal structure of carnidazole form II from synchrotron X-ray powder diffraction: structural comparison with form I, the hydrated form and the low energy conformations in vacuo.

    PubMed

    de Armas, Héctor Novoa; Peeters, Oswald M; Blaton, Norbert; Van den Mooter, Guy; De Ridder, Dirk J A; Schenk, Henk

    2006-10-01

    The crystal structure of carnidazole form II, O-methyl [2-(2-methyl-5-nitro-1H-imidazole-1-yl)ethyl]thiocarbamate, has been determined using synchrotron X-ray powder diffraction in combination with simulated annealing and whole profile pattern matching, and refined by the Rietveld method. For structure solution, 12 degrees of freedom were defined: one motion group and six torsions. Form II crystallizes in space group P2(1)/n, Z=4, with unit cell parameters after Rietveld refinement: a=13.915(4), b=8.095(2), c=10.649(3) A, beta=110.83(1) degrees, and V=1121.1(5) A3. The two polymorphic forms, as well as the hydrate, crystallize in the monoclinic space group P2(1)/n having four molecules in the cell. In form II, the molecules are held together by forming two infinite zig-zag chains via hydrogen bonds of the type N--H...N, the same pattern as in form I. A conformational study of carnidazole, at semiempirical PM3 level, was performed using stochastic approaches based on modification of the flexible torsion angles. The values of the torsion angles for the molecules of the two polymorphic forms and the hydrate of carnidazole are compared to those obtained from the conformational search. Form I and form II are enantiotropic polymorphic pairs this agrees with the fact that the two forms are conformational polymorphs.

  11. Strontium magnesium phosphate, Sr(2+x)Mg(3-x)P4O15 (x ~ 0.36), from laboratory X-ray powder data.

    PubMed

    Hong, Jung-Hwa; Song, Seung-Wan; Hong, Seung-Tae

    2011-01-01

    The previously unknown crystal structure of strontium magnesium phosphate, Sr(2+x)Mg(3-x)P(4)O(15) (x ~ 0.36), determined and refined from laboratory powder X-ray diffraction data, represents a new structure type. The title compound was synthesized by high-temperature solid-state reaction and it crystallizes in the orthorhombic space group Cmcm. It was earlier thought to be stoichiometric Sr(2)Mg(3)P(4)O(15), but our structural study indicates the nonstoichiometric composition. The asymmetric unit contains one Sr (site symmetry ..m on special position 8g), one M (= Mg 64%/Sr 36%; site symmetry 2/m.. on special position 4b), one Mg (site symmetry 2.. on special position 8e), two P (site symmetry m.. on special position 8f and site symmetry ..m on special position 8g), and six O sites [two on general positions 16h, two on 8g, one on 8f and one on special position 4c (site symmetry m2m)]. The nonstoichiometry is due to the mixing of magnesium and strontium ions on the M site. The structure consists of three-dimensional networks of MgO(4) and PO(4) tetrahedra, and MO(6) octahedra with the other strontium ions occupying the larger cavities surrounded by ten O atoms. All the polyhedra are connected by corner-sharing except the edge-sharing MO(6) octahedra forming one-dimensional arrangements along [001].

  12. Rietveld refinement of the semiconducting system Bi{sub 2-x}Fe{sub x}Te{sub 3} from X-ray powder diffraction

    SciTech Connect

    Adam, Alia

    2007-12-04

    The semiconducting system Bi{sub 2-x}Fe{sub x}Te{sub 3} (x = 0.0, 0.02, 0.04 and 0.08) was synthesized at 1000 deg. C for 30 h. The scanning electron microscope (SEM) image reveals the tendency of the Bi{sub 2-x}Fe{sub x}Te{sub 3} system to form a sheet structure with more pronounced alignment and to enhance the formation of some microstructure tubes. The structure of the system under study was refined on the basis of X-ray powder diffraction data using the Rietveld method. The analysis revealed the complete miscibility of Fe in the Bi{sub 2}Te{sub 3} matrix and hence the formation of single phase. The system crystallizes in the space group R-3m [1 6 6]. The lattice parameters and the unit cell size slightly change by the incorporation of Fe. The refinement of instrumental and structural parameters led to reliable values for the R{sub B}, R{sub F} and Chi{sup 2}.

  13. Static and Dynamical Structural Investigations of Metal-Oxide Nanocrystals by Powder X-ray Diffraction: Colloidal Tungsten Oxide as a Case Study.

    PubMed

    Caliandro, Rocco; Sibillano, Teresa; Belviso, B Danilo; Scarfiello, Riccardo; Hanson, Jonathan C; Dooryhee, Eric; Manca, Michele; Cozzoli, P Davide; Giannini, Cinzia

    2016-03-01

    We have developed a general X-ray powder diffraction (XPD) methodology for the simultaneous structural and compositional characterization of inorganic nanomaterials. The approach is validated on colloidal tungsten oxide nanocrystals (WO3-x NCs), as a model polymorphic nanoscale material system. Rod-shaped WO3-x NCs with different crystal structure and stoichiometry are comparatively investigated under an inert atmosphere and after prolonged air exposure. An initial structural model for the as-synthesized NCs is preliminarily identified by means of Rietveld analysis against several reference crystal phases, followed by atomic pair distribution function (PDF) refinement of the best-matching candidates (static analysis). Subtle stoichiometry deviations from the corresponding bulk standards are revealed. NCs exposed to air at room temperature are monitored by XPD measurements at scheduled time intervals. The static PDF analysis is complemented with an investigation into the evolution of the WO3-x NC structure, performed by applying the modulation enhanced diffraction technique to the whole time series of XPD profiles (dynamical analysis). Prolonged contact with ambient air is found to cause an appreciable increase in the static disorder of the O atoms in the WO3-x NC lattice, rather than a variation in stoichiometry. The time behavior of such structural change is identified on the basis of multivariate analysis. PMID:26756645

  14. In situ synchrotron X-ray powder diffraction for studying the role of induced structural defects on the thermoluminescence mechanism of nanocrystalline LiF.

    PubMed

    El Ashmawy, Mostafa; Amer, Hany; Abdellatief, Mahmoud

    2016-03-01

    The correlation between the thermoluminescence (TL) response of nanocrystalline LiF and its microstructure was studied. To investigate the detailed TL mechanism, the glow curves of nanocrystalline LiF samples produced by high-energy ball-milling were analyzed. The microstructure of the prepared samples was analyzed by synchrotron X-ray powder diffraction (XRPD) at room temperature. Then, the microstructure of a representative pulverized sample was investigated in detail by performing in situ XRPD in both isothermal and non-isothermal modes. In the present study, the dislocations produced by ball-milling alter the microstructure of the lattice where the relative concentration of the vacancies, responsible for the TL response, changes with milling time. An enhancement in the TL response was recorded for nanocrystalline LiF at high-temperature traps (after dislocations recovery starts >425 K). It is also found that vacancies are playing a major role in the dislocations recovery mechanism. Moreover, the interactions among vacancies-dislocations and/or dislocations-dislocations weaken the TL response. PMID:26917138

  15. The Optics and Alignment of the Divergent Beam Laboratory X-ray Powder Diffractometer and its Calibration Using NIST Standard Reference Materials

    PubMed Central

    Cline, James P.; Mendenhall, Marcus H.; Black, David; Windover, Donald; Henins, Albert

    2015-01-01

    The laboratory X-ray powder diffractometer is one of the primary analytical tools in materials science. It is applicable to nearly any crystalline material, and with advanced data analysis methods, it can provide a wealth of information concerning sample character. Data from these machines, however, are beset by a complex aberration function that can be addressed through calibration with the use of NIST Standard Reference Materials (SRMs). Laboratory diffractometers can be set up in a range of optical geometries; considered herein are those of Bragg-Brentano divergent beam configuration using both incident and diffracted beam monochromators. We review the origin of the various aberrations affecting instruments of this geometry and the methods developed at NIST to align these machines in a first principles context. Data analysis methods are considered as being in two distinct categories: those that use empirical methods to parameterize the nature of the data for subsequent analysis, and those that use model functions to link the observation directly to a specific aspect of the experiment. We consider a multifaceted approach to instrument calibration using both the empirical and model based data analysis methods. The particular benefits of the fundamental parameters approach are reviewed. PMID:26958446

  16. The Stoichiometry of Synthetic Alunite as a Function of Hydrothermal Aging Investigated by Solid-State NMR Spectroscopy, Powder X-ray Diffraction and Infrared Spectroscopy

    SciTech Connect

    Grube, Elisabeth; Nielsen, Ulla Gro

    2015-05-01

    The stoichiometry of a series of synthetic alunite [nominally KAl3(SO4)2(OH)6] samples prepared by hydrothermal methods as a function of reaction time (1–31 days) has been investigated by powder X-ray diffraction, Fourier transform infrared spectroscopy as well as solid-state 1H and 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The 1H MAS NMR spectra recorded at high magnetic field (21.1 T, 900 MHz) allowed for a clear separation of the different proton environments and for quantitative determination of the aluminum vacancy concentration as a function of time. The concentration of structural defects determined from, i.e., aluminum vacancies was reduced from 4 to 1 %, as the reaction time was extended from one to 31 days based on 1H MAS NMR. This was further supported by an increase of the unit cell parameter c, which is indicative of the relative concentration of potassium defects present, from 17.261(1) to 17.324(5) Å. Solid-state 27Al MAS NMR revealed a decrease in the defect concentration as a function of time and showed the presence of 7–10 % impurities in the samples.

  17. In situ synchrotron X-ray powder diffraction for studying the role of induced structural defects on the thermoluminescence mechanism of nanocrystalline LiF.

    PubMed

    El Ashmawy, Mostafa; Amer, Hany; Abdellatief, Mahmoud

    2016-03-01

    The correlation between the thermoluminescence (TL) response of nanocrystalline LiF and its microstructure was studied. To investigate the detailed TL mechanism, the glow curves of nanocrystalline LiF samples produced by high-energy ball-milling were analyzed. The microstructure of the prepared samples was analyzed by synchrotron X-ray powder diffraction (XRPD) at room temperature. Then, the microstructure of a representative pulverized sample was investigated in detail by performing in situ XRPD in both isothermal and non-isothermal modes. In the present study, the dislocations produced by ball-milling alter the microstructure of the lattice where the relative concentration of the vacancies, responsible for the TL response, changes with milling time. An enhancement in the TL response was recorded for nanocrystalline LiF at high-temperature traps (after dislocations recovery starts >425 K). It is also found that vacancies are playing a major role in the dislocations recovery mechanism. Moreover, the interactions among vacancies-dislocations and/or dislocations-dislocations weaken the TL response.

  18. Obtaining aluminas from the thermal decomposition of their different precursors: An {sup 27}Al MAS NMR and X-ray powder diffraction studies

    SciTech Connect

    Chagas, L.H.; De Carvalho, G.S.G.; San Gil, R.A.S.; Chiaro, S.S.X.; Leitão, A.A.; Diniz, R.

    2014-01-01

    Graphical abstract: - Highlights: • We synthesized three precursors of alumina from different methods. • The calcination of the precursors generated several alumina polymorphs. • XRD and NMR were used for structural investigation of the polymorphs. • The synthesis route determines the structural and textural properties of the solids. - Abstract: A commercial sample of Boehmite was used as precursor of alumina polymorphs. For comparison, three other precursors were synthesized from different methods. Particularly, the use of excess of urea promoted a very crystalline form of basic aluminum carbonate. The characteristics of the four precursors were investigated by thermal, vibrational and X-ray powder diffraction (XRD) analysis. Additionally, the nuclear magnetic resonance, with magic angle spinning ({sup 27}Al MAS NMR), was used to verify the coordination of aluminum cations. Each precursor was calcined at various temperatures generating alumina polymorphs, which were structurally analyzed by XRD and {sup 27}Al MAS NMR. Due to interest in catalysis supports, special attention was given to the γ-Al{sub 2}O{sub 3} phase, which in addition to structural investigation was subjected to textural analysis. The results showed that, from different synthesis procedures and common route of calcination, one can obtain materials with the same composition but with different structural and textural properties, which in turn can significantly influence the performance of a supported catalyst.

  19. Operando Synchrotron X-ray Powder Diffraction and Modulated-Excitation Infrared Spectroscopy Elucidate the CO2 Promotion on a Commercial Methanol Synthesis Catalyst.

    PubMed

    Martin, Oliver; Mondelli, Cecilia; Cervellino, Antonio; Ferri, Davide; Curulla-Ferré, Daniel; Pérez-Ramírez, Javier

    2016-09-01

    Optimal amounts of CO2 are added to syngas to boost the methanol synthesis rate on Cu-ZnO-Al2 O3 in the industrial process. The reason for CO2 promotion is not sufficiently understood at the particle level due to the catalyst complexity and the high demands of characterization under true reaction conditions. Herein, we applied operando synchrotron X-ray powder diffraction and modulated-excitation infrared spectroscopy on a commercial catalyst to gain insights into its morphology and surface chemistry. These studies unveiled that Cu and ZnO agglomerate and ZnO particles flatten under CO/H2 and/or CO2 /H2 . Under the optimal CO/CO2 /H2 mixture, sintering is prevented and ZnO crystals adopt an elongated shape due to the minimal presence of the H2 O byproduct, enhancing the water-gas shift activity and thus the methanol production. Our results provide a rationale to the CO2 promotion emphasizing the importance of advanced analytical methods to establish structure-performance relations in heterogeneous catalysis. PMID:27383374

  20. Estimation of Crystallinity of Nifedipine-Polyvinylpyrrolidone Solid Dispersion by Usage of Terahertz Time-Domain Spectroscopy and of X-Ray Powder Diffractometer.

    PubMed

    Takeuchi, Issei; Shimakura, Kemmaro; Kuroda, Hideki; Nakajima, Takehisa; Goto, Satoru; Makino, Kimiko

    2015-12-01

    Crystalline state of pharmaceutical materials is of great importance in preparation of pharmaceutics, because their physicochemical properties affect bioavailability, quality of products, therapeutic level and manufacturing process. In this study, we have estimated time-dependent changes of nifedipine in nifedipine-polyvinylpyrrolidone (PVP) solid dispersion by measuring terahertz time-domain spectroscopy (THz-TDS) and by X-ray powder diffractometry (XRPD), and compared their correlativity. Crystallinity of nifedipine-PVP solid dispersion was changed by storing the amorphous sample at 25°C-75°C and relative humidity of over 80% for 0.25-24.00 h. To compare the results of two types of measurements, we have used a general method of linear regression analysis. Crystallinities estimated using THz-TDS were plotted on the x-axis and that of XRPD were on the y-axis. From the result of the calculation, the correlativity of them was confirmed. THz-TDS has the capability of becoming the replacement of XRPD.

  1. Formation of γ-Fe 2O 3 nanoparticles and vacancy ordering: An in situ X-ray powder diffraction study

    NASA Astrophysics Data System (ADS)

    Jørgensen, Jens-Erik; Mosegaard, Lene; Thomsen, Line E.; Jensen, Torben R.; Hanson, Jonathan C.

    2007-01-01

    The formation of maghemite, γ-Fe 2O 3 nanoparticles has been studied by in situ X-ray powder diffraction. The maghemite was formed by thermal decomposition of an amorphous precursor compound made by reacting lauric acid, CH 3(CH 2) 10COOH with Fe(NO 3) 3·9H 2O. It has been shown that cubic γ-Fe 2O 3 was formed directly from the amorphous precursor and that vacancy ordering starts about 45 min later at 305 °C resulting in a tripled unit cell along the c-axis. The kinetics of grain growth was found to obey a power law with growth exponents n equal to 0.136(6) and 0.103(5) at 305 and 340 °C, respectively. Particles with average sizes of 12 and 13 nm were obtained in 86 and 76 min at 305 and 340 °C, respectively. The structure of cubic and vacancy ordered phases of γ-Fe 2O 3 was studied at 305 °C by Rietveld refinements.

  2. Synchrotron X-ray powder diffraction and convergent beam electron diffraction studies on the cubic phase of MgV{sub 2}O{sub 4} spinel

    SciTech Connect

    Niitaka, Seiji; Lee, Soyeon; Oshima, Yoshifumi; Kato, Kenichi; Hashizume, Daisuke; Takata, Masaki; Takagi, Hidenori

    2014-07-01

    The A V{sub 2}O{sub 4} (A=Mg{sup 2+}, Zn{sup 2+}, Cd{sup 2+}) spinels are three-dimensional spin-1 frustrated systems with orbital degree of freedom, which have been known to possess intriguing orbital states causing releases of spin frustration at low temperatures. We have performed synchrotron X-ray and convergent beam electron diffraction measurements for one of these vanadates, MgV{sub 2}O{sub 4} in order to clarify its crystal structure in the high temperature cubic phase, which is regarded as an important starting point for understanding the details of the low temperature phase. We have successfully observed that the [001] zone axis convergent beam electron diffraction pattern exhibits 4mm symmetry, suggesting the space group of Fd3{sup ¯}m in the cubic MgV{sub 2}O{sub 4}. It has also been demonstrated that the crystal structure of the cubic MgV{sub 2}O{sub 4} contains VO{sub 6} octahedra elongated along the threefold rotation axis. Based on our results, we discuss the orbital states of MgV{sub 2}O{sub 4} as well as the other spinel vanadates. - Graphical abstract: Precise geometry of the VO{sub 6} octahedra in the cubic phase of MgV{sub 2}O{sub 4} spinel determined with the synchrotron powder XRD data. - Highlights: • We examined the crystal structure of the cubic phase of MgV{sub 2}O{sub 4} spinel. • We prepared the single crystal and powdered sample of MgV{sub 2}O{sub 4} with high quality. • The result of the CBED measurement agrees with the space group of Fd3{sup ¯}m in the phase. • The cubic phase has VO{sub 6} octahedra elongated along the threefold rotation axis.

  3. Maximum Entropy Method and Charge Flipping, a Powerful Combination to Visualize the True Nature of Structural Disorder from in situ X-ray Powder Diffraction Data

    SciTech Connect

    Samy, A.; Dinnebier, R; van Smaalen, S; Jansen, M

    2010-01-01

    In a systematic approach, the ability of the Maximum Entropy Method (MEM) to reconstruct the most probable electron density of highly disordered crystal structures from X-ray powder diffraction data was evaluated. As a case study, the ambient temperature crystal structures of disordered {alpha}-Rb{sub 2}[C{sub 2}O{sub 4}] and {alpha}-Rb{sub 2}[CO{sub 3}] and ordered {delta}-K{sub 2}[C{sub 2}O{sub 4}] were investigated in detail with the aim of revealing the 'true' nature of the apparent disorder. Different combinations of F (based on phased structure factors) and G constraints (based on structure-factor amplitudes) from different sources were applied in MEM calculations. In particular, a new combination of the MEM with the recently developed charge-flipping algorithm with histogram matching for powder diffraction data (pCF) was successfully introduced to avoid the inevitable bias of the phases of the structure-factor amplitudes by the Rietveld model. Completely ab initio electron-density distributions have been obtained with the MEM applied to a combination of structure-factor amplitudes from Le Bail fits with phases derived from pCF. All features of the crystal structures, in particular the disorder of the oxalate and carbonate anions, and the displacements of the cations, are clearly obtained. This approach bears the potential of a fast method of electron-density determination, even for highly disordered materials. All the MEM maps obtained in this work were compared with the MEM map derived from the best Rietveld refined model. In general, the phased observed structure factors obtained from Rietveld refinement (applying F and G constraints) were found to give the closest description of the experimental data and thus lead to the most accurate image of the actual disorder.

  4. Low-temperature high magnetic field powder x-ray diffraction setup for field-induced structural phase transition studies from 2 to 300 K and at 0 to 8-T field

    NASA Astrophysics Data System (ADS)

    Shahee, Aga; Sharma, Shivani; Kumar, Dhirendra; Yadav, Poonam; Bhardwaj, Preeti; Ghodke, Nandkishor; Singh, Kiran; Lalla, N. P.; Chaddah, P.

    2016-10-01

    A low-temperature and high magnetic field powder x-ray diffractometer (XRD) has been developed at UGC-DAE CSR (UGC: University Grant Commission, DAE: Department of Atomic Energy, and CSR: Consortium for scientific research), Indore, India. The setup has been developed around an 18 kW rotating anode x-ray source delivering Cu-Kα x-rays coming from a vertical line source. It works in a symmetric θ-2θ parallel beam geometry. It consists of a liquid helium cryostat with an 8 T split-pair Nb-Ti superconducting magnet comprising two x-ray windows each covering an angular range of 65°. This is mounted on a non-magnetic type heavy duty goniometer equipped with all necessary motions along with data collection accessories. The incident x-ray beam has been made parallel using a parabolic multilayer mirror. The scattered x-ray is detected using a NaI detector through a 0.1° acceptance solar collimator. To control the motions of the goniometer, a computer programme has been developed. The wide-angle scattering data can be collected in a range of 2°-115° of 2θ with a resolution of ˜0.1°. The whole setup is tightly shielded for the scattered x-rays using a lead hutch. The functioning of the goniometer and the artifacts arising possibly due to the effect of stray magnetic field on the goniometer motions, on the x-ray source, and on the detector have been characterized by collecting powder XRD data of a National Institute of Standards and Technology certified standard reference material LaB6 (SRM-660b) and Si powder in zero-field and in-field conditions. Occurrence of field induced structural-phase transitions has been demonstrated on various samples like Pr0.5Sr0.5MnO3, Nd0.49Sr0.51MnO3-δ and La0.175Pr0.45Ca0.375MnO3 by collecting data in zero field cool and field cool conditions.

  5. Thoracic spine x-ray

    MedlinePlus

    Vertebral radiography; X-ray - spine; Thoracic x-ray; Spine x-ray; Thoracic spine films; Back films ... care provider's office. You will lie on the x-ray table in different positions. If the x-ray ...

  6. Water adsorption, solvation and deliquescence of alkali halide thin films on SiO2 studied by ambient pressure X-ray photoelectron spectroscopy

    SciTech Connect

    Arima, Kenta; Jiang, Peng; Deng, Xingyi; Bluhm, Henrik; Salmeron, Miquel

    2010-03-31

    The adsorption of water on KBr thin films evaporated onto SiO2 was investigated as a function of relative humidity (RH) by ambient pressure X-ray photoelectron spectroscopy. At 30percent RH adsorbed water reaches a coverage of approximately one monolayer. As the humidity continues to increase, the coverage of water remains constant or increases very slowly until 60percent RH, followed by a rapid increase up to 100percent RH. At low RH a significant number of the Br atoms are lost due to irradiation damage. With increasing humidity solvation increases ion mobility and gives rise to a partial recovery of the Br/K ratio. Above 60percent RH the increase of the Br/K ratio accelerates. Above the deliquescence point (85percent RH), the thickness of the water layer continues to increase and reaches more than three layers near saturation. The enhancement of the Br/K ratio at this stage is roughly a factor 2.3 on a 0.5 nm KBr film, indicating a strong preferential segregation of Br ions to the surface of the thin saline solution on SiO2.

  7. [X-ray absorption spectroscopic evidence for the formation of Pb(II) inner-sphere adsorption complexes and precipitates at the alkaline soil-water interface].

    PubMed

    Hu, Ning-Jing; Luo, Yong-Ming; Huang, Peng; Hu, Tian-Dou; Xie, Ya-Ning; Wu, Zi-Yu; Shi, Xue-Fa

    2011-02-01

    Adsorption mechanisms of Pb on soil with high CaCO3 content were investigated by combined batch sorption and X-ray absorption fine structure (XAFS). Date from the batch equilibrium studies showed that Pb sorption was nonlinear and was well fitted to Langmiur isotherm. The XAFS data indicated that Pb could be adsorbed via the inner-sphere complex, the precipitation of calcium carbonate containing Pb (PbCaCO3), and outer-sphere Pb sorption complex. The formations of inner-sphere complexes and PbCaCO3 implied strong metal interactions with the surfaces the mechanistic reason for the affinity of Pb for CaCO3 as observed in macroscopic studies. At low metal concentration, 500 mg x L(-1) of initial Pb, radial distance of the first-shell Pb-O (R1) was 0.169 2 nm, however, at 1 000 mg x L(-1) of initial Pb, the R1 was 0.166 8 nm. These revealed that the percentage of inner-sphere complexes increased when the initial Pb was increased from 500 to 1 000 mg x L(-1). PMID:21510427

  8. An X-ray photoelectron spectroscopy study of BF3 adsorption on positively and negatively poled LiNbO3 (0001)

    NASA Astrophysics Data System (ADS)

    Herdiech, M. W.; Mönig, H.; Altman, E. I.

    2014-08-01

    Adsorption of the strong Lewis acid BF3 was investigated to probe the sensitivity of the Lewis basicity of surface oxygens on LiNbO3 (0001) to the ferroelectric polarization direction. Adsorption and desorption were characterized by using X-ray photoelectron spectroscopy (XPS) to monitor the intensity and binding energy of the F 1s core level as a function of BF3 exposure and temperature. The results indicate that both BF3 uptake and desorption are very similar on the positively and negatively poled surfaces. In particular, BF3 only weakly adsorbs with the majority of the adsorbed BF3 desorbing below 200 K. Despite the similarities in the uptake and desorption behavior, the binding energy of the F 1s peak relative to the substrate Nb 3d5/2 peak was sensitive to the polarization direction, with the F 1s peak occurring at a binding energy up to 0.3 eV lower on positively poled than negatively poled LiNbO3 for equivalent BF3 exposures. Rather than reflecting a difference in bonding to the surface, however, this shift could be associated with oppositely oriented dipoles at the positively and negatively poled surfaces creating opposite band offsets between the adsorbate and the substrate. A similar effect was observed with lead zirconate titanate thin films where the Pb 4f XPS peak position changes as a function of temperature as a result of the pyroelectric effect which changes the magnitude of the surface and interface dipoles.

  9. Pulsed supercritical synthesis of anatase TiO2 nanoparticles in a water-isopropanol mixture studied by in situ powder X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Eltzholtz, Jakob Rostgaard; Tyrsted, Christoffer; Jensen, Kirsten Marie Ørnsbjerg; Bremholm, Martin; Christensen, Mogens; Becker-Christensen, Jacob; Iversen, Bo Brummerstedt

    2013-02-01

    A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania nanoparticles were synthesized in a 50/50 mixture of water and isopropanol near and above the critical point of water (P = 250 bar, T = 300, 350, 400, 450, 500 and 550 °C). The evolution of the reaction product was followed by sequentially recording PXRD patterns with a time resolution of less than two seconds. The crystallite size of titania is found to depend on both temperature and residence time, and increasing either parameter leads to larger crystallites. A simple adjustment of either temperature or residence time provides a direct method for gram scale production of anatase nanoparticles of average crystallite sizes between 7 and 35 nm, thus giving the option of synthesizing tailor-made nanoparticles. Modeling of the in situ growth curves using an Avrami growth model gave an activation energy of 66(19) kJ mol-1 for the initial crystallization. The in situ PXRD data also provide direct information about the size dependent macrostrain in the nanoparticles and with decreasing crystallite size the unit cell contracts, especially along the c-direction. This agrees well with previous ex situ results obtained for hydrothermal synthesis of titania nanoparticles.A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania

  10. In situ high-pressure synchrotron X-ray powder diffraction study of tunnel manganese oxide minerals: hollandite, romanechite, and todorokite

    NASA Astrophysics Data System (ADS)

    Hwang, Gil Chan; Post, Jeffrey E.; Lee, Yongjae

    2015-05-01

    In situ high-pressure synchrotron X-ray powder diffraction study of three tunnel manganese oxide minerals (hollandite with 2 × 2 MnO6 octahedra tunnels, romanechite with 2 × 3 tunnels, and todorokite with 3 × 3 tunnels) was performed using a diamond anvil cell and nominally penetrating alcohol and water mixture as a pressure-transmitting medium up to ~8 GPa. Bulk moduli ( B 0) calculated using Murnaghan's equation of state are inversely proportional to the size of the tunnel, i.e., 134(4) GPa for hollandite ( I2/m), 108(2) GPa for romanechite ( C2/m), and 67(5) GPa for todorokite ( P2/m). On the other hand, axial compressibilities show different elastic anisotropies depending on the size of the tunnel, i.e., ( a/ a 0) = -0.00066(3) GPa-1, ( b/ b 0) = 0.00179(8) GPa-1, ( c/ c 0) = 0.00637(4) GPa-1 [ c > b > a] for hollandite; ( a/ a 0) = 0.00485(4) GPa-1, ( b/ b 0) = 0.0016(1) GPa-1, ( c/ c 0) = 0.00199(8) GPa-1 [ a > c > b] for romanechite; and ( a/ a 0) = 0.00826(9) GPa-1, ( b/ b 0) = 0.0054(1) GPa-1, ( c/ c 0) = 0.00081(8) GPa-1 [ a > b > c] for todorokite. Overall, the degree of tunnel distortion increases with increasing pressure and correlates with the size of the tunnel, which is evidenced by the gradual increases in the monoclinic β angles up to 3 GPa of 0.62°, 0.8°, and 1.15° in hollandite, romanechite, and todorokite, respectively. The compression of tunnel manganese oxides is related to the tunnel distortion and the size of the tunnel.

  11. Crystal-structure analysis of four mineral samples of anhydrite, CaSO[subscript 4], using synchrotron high-resolution powder X-ray diffraction data

    SciTech Connect

    Antao, Sytle M.

    2014-05-28

    The crystal structures of four samples of anhydrite, CaSO{sub 4}, were obtained by Rietveld refinements using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data and space group Amma. As an example, for one sample of anhydrite from Hants County, Nova Scotia, the unit-cell parameters are a = 7.00032(2), b = 6.99234(1), c = 6.24097(1) {angstrom}, and V = 305.487(1) {angstrom}{sup 3} with a > b. The eight-coordinated Ca atom has an average distance of 2.4667(4) {angstrom}. The tetrahedral SO{sub 4} group has two independent S-O distances of 1.484(1) to O1 and 1.478(1) {angstrom} to O2 and an average distance of 1.4810(5) {angstrom}. The three independent O-S-O angles [108.99(8) x 1, 110.38(3) x 4, 106.34(9){sup o} x 1; average [6] = 109.47(2){sup o}] and S-O distances indicate that the geometry of the SO{sub 4} group is quite distorted in anhydrite. The four anhydrite samples have structural trends where the a, b, and c unit-cell parameters increase linearly with increasing unit-cell volume, V, and their average and distances are nearly constant. The grand mean = 2.4660(2) {angstrom}, and grand mean = 1.4848(3) {angstrom}, the latter is longer than 1.480(1) {angstrom} in celestite, SrSO{sub 4}, as expected.

  12. Hidden Superlattice in Tl2(SC6H4S) and Tl2(SeC6H4Se) Solved from Powder X-ray Diffraction

    SciTech Connect

    K Stone; D Turner; M Singh; T Vaid; P Stephens

    2011-12-31

    The crystal structures of the isostructural title compounds poly[({mu}-benzene-1,4-dithiolato)dithallium], Tl{sub 2}(SC{sub 6}H{sub 4}S), and poly[({mu}-benzene-1,4-diselenolato)dithallium], Tl{sub 2}(SeC{sub 6}H{sub 4}Se), were solved by simulated annealing from high-resolution synchrotron X-ray powder diffraction. Rietveld refinements of an initial structure with one formula unit per triclinic cell gave satisfactory agreement with the data, but led to a structure with impossibly close non-bonded contacts. A disordered model was proposed to alleviate this problem, but an alternative supercell structure leads to slightly improved agreement with the data. The isostructural superlattice structures were confirmed for both compounds through additional data collection, with substantially better counting statistics, which revealed the presence of very weak superlattice peaks not previously seen. Overall, each structure contains Tl-S or Tl-Se two-dimensional networks, connected by phenylene bridges. The sulfur (or selenium) coordination sphere around each thallium is a highly distorted square pyramid or a 'see-saw' shape, depending upon how many Tl-S or Tl-Se interactions are considered to be bonds. In addition, the two compounds contain pairs of Tl{sup I} ions that interact through a closed-shell 'thallophilic' interaction: in the sulfur compound there are two inequivalent pairs of Tl atoms with Tl-Tl distances of 3.49 and 3.58 {angstrom}, while in the selenium compound those Tl-Tl interactions are at 3.54 and 3.63 {angstrom}.

  13. Dental x-rays

    MedlinePlus

    X-ray - teeth; Radiograph - dental; Bitewings; Periapical film; Panoramic film; Digital image ... dentist's office. There are many types of dental x-rays. Some of them are: Bitewing. Shows the crown ...

  14. X-ray (image)

    MedlinePlus

    X-rays are a form of ionizing radiation that can penetrate the body to form an image on ... will be shades of gray depending on density. X-rays can provide information about obstructions, tumors, and other ...

  15. X-Ray Lasers

    ERIC Educational Resources Information Center

    Chapline, George; Wood, Lowell

    1975-01-01

    Outlines the prospects of generating coherent x rays using high-power lasers and indentifies problem areas in their development. Indicates possible applications for coherent x rays in the fields of chemistry, biology, and crystallography. (GS)

  16. X Ray Topography

    ERIC Educational Resources Information Center

    Balchin, A. A.

    1974-01-01

    Discusses some aspects in X-ray topography, including formation of dislocations, characteristics of stacking faults, x-ray contrast in defect inspection, Berg-Barrett technique, and Lang traversing crystal and Borrmann's methods. (CC)

  17. Optical absorption characteristics in the assessment of powder phosphor-based x-ray detectors: from nano- to micro-scale

    NASA Astrophysics Data System (ADS)

    Liaparinos, P. F.

    2015-11-01

    X-ray phosphor-based detectors have enormously improved the quality of medical imaging examinations through the optimization of optical diffusion. In recent years, with the development of science and technology in the field of materials, improved powder phosphors require structural and optical properties that contribute to better optical signal propagation. The purpose of this paper was to provide a quantitative and qualitative understanding of the optical absorption characteristics in the assessment of powder phosphor-based detectors (from nano- scale up to micro-scale). Variations on the optical absorption parameters (i.e. the light extinction coefficient {{m}\\text{ext}} and the percentage probability of light absorption p%) were evaluated based on Mie calculations examining a wide range of light wavelengths, particle refractive indices and sizes. To model and assess the effects of the aforementioned parameters on optical diffusion, Monte Carlo simulation techniques were employed considering: (i) phosphors of different layer thickness, 100 μm (thin layer) and 300 μm (thick layer), respectively, (ii) light extinction coefficient values, 1, 3 and 6 μm-1, and (iii) percentage probability of light absorption p% in the range 10-4-10-2. Results showed that the {{m}\\text{ext}} coefficient is high for phosphor grains in the submicron scale and for low light wavelengths. At higher wavelengths (above 650 nm), optical quanta follow approximately similar depths until interaction for grain diameter 500 nm and 1 μm. Regarding the variability of the refractive index, high variations of the {{m}\\text{ext}} coefficient occurred above 1.6. Furthermore, results derived from Monte Carlo modeling showed that high spatial resolution phosphors can be accomplished by increasing the {{m}\\text{ext}} parameter. More specifically, the FWHM was found to decrease (i.e. higher resolution): (i) 4.8% at 100 μm and (ii) 9.5%, at 300 μm layer thickness. This study attempted to

  18. Optical absorption characteristics in the assessment of powder phosphor-based x-ray detectors: from nano- to micro-scale.

    PubMed

    Liaparinos, P F

    2015-11-21

    X-ray phosphor-based detectors have enormously improved the quality of medical imaging examinations through the optimization of optical diffusion. In recent years, with the development of science and technology in the field of materials, improved powder phosphors require structural and optical properties that contribute to better optical signal propagation. The purpose of this paper was to provide a quantitative and qualitative understanding of the optical absorption characteristics in the assessment of powder phosphor-based detectors (from nano- scale up to micro-scale). Variations on the optical absorption parameters (i.e. the light extinction coefficient [Formula: see text] and the percentage probability of light absorption p%) were evaluated based on Mie calculations examining a wide range of light wavelengths, particle refractive indices and sizes. To model and assess the effects of the aforementioned parameters on optical diffusion, Monte Carlo simulation techniques were employed considering: (i) phosphors of different layer thickness, 100 μm (thin layer) and 300 μm (thick layer), respectively, (ii) light extinction coefficient values, 1, 3 and 6 μm(-1), and (iii) percentage probability of light absorption p% in the range 10(-4)-10(-2). Results showed that the [Formula: see text] coefficient is high for phosphor grains in the submicron scale and for low light wavelengths. At higher wavelengths (above 650 nm), optical quanta follow approximately similar depths until interaction for grain diameter 500 nm and 1 μm. Regarding the variability of the refractive index, high variations of the [Formula: see text] coefficient occurred above 1.6. Furthermore, results derived from Monte Carlo modeling showed that high spatial resolution phosphors can be accomplished by increasing the [Formula: see text] parameter. More specifically, the FWHM was found to decrease (i.e. higher resolution): (i) 4.8% at 100 μm and (ii) 9.5%, at 300 μm layer thickness. This study

  19. X-Ray Imaging

    MedlinePlus

    ... Brain Surgery Imaging Clinical Trials Basics Patient Information X-Ray Imaging Print This Page X-ray imaging is perhaps the most familiar type of imaging. Images produced by X-rays are due to the different absorption rates of ...

  20. X-Rays

    MedlinePlus

    X-rays are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of the inside of your ... different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat and ...

  1. Hand x-ray

    MedlinePlus

    X-ray - hand ... A hand x-ray is taken in a hospital radiology department or your health care provider's office by an ... technician. You will be asked to place your hand on the x-ray table, and keep it ...

  2. The Long-Term Fate of Cu2+, Zn2+, and Pb2+ Adsorption Complexes at the Calcite Surface: An X-ray Absorption Spectroscopy Study

    SciTech Connect

    Elzinga,E.; Rouff, A.; Reeder, R.

    2006-01-01

    In this study, the speciation of Zn{sup 2+}, Pb{sup 2+}, and Cu{sup 2+} ions sorbed at the calcite surface was monitored during a 2.5-year reaction period, using extended X-ray absorption spectroscopy to characterize metal speciation on the molecular scale. Experiments were performed using pre-equilibrated calcite-water suspensions of pH 8.3, at metal concentrations below the solubility of metal hydroxide and carbonate precipitates, and at constant metal surface loadings. The EXAFS results indicate that all three metals remained coordinated at the calcite surface as inner-sphere adsorption complexes during the 2.5-year ageing period, with no evidence to suggest slow formation of dilute metal-calcite solid solutions under the reaction conditions employed. All three divalent metals were found to form non-octahedral complexes upon coordination to the calcite surface, with Zn{sup 2+} adsorbing as a tetrahedral complex, Cu{sup 2+} as a Jahn-Teller distorted octahedral complex, and Pb{sup 2+} coordinating as a trigonal- or square-pyramidal surface complex. The non-octahedral configurations of these surface complexes may have hindered metal transfer from the calcite surface into the bulk, where Ca{sup 2+} is in octahedral coordination with respect to first-shell O. The use of pre-equilibrated calcite suspensions, with no net calcite dissolution or precipitation, likely prevented metal incorporation into the lattice as a result of surface recrystallization. The results from this study imply that ageing alone does not increase the stability of Zn{sup 2+}, Pb{sup 2+}, and Cu{sup 2+} partitioning to calcite if equilibrium with the solution is maintained during reaction; under these conditions, these metals are likely to remain available for exchange even after extended sorption times.

  3. Effect of calcium on adsorption capacity of powdered activated carbon.

    PubMed

    Li, Gang; Shang, Junteng; Wang, Ying; Li, Yansheng; Gao, Hong

    2013-12-01

    We investigated the effect of calcium ion on the adsorption of humic acid (HA) (as a target pollutant) by powered activated carbon. The HA adsorption isotherms at different pH and kinetics of two different solutions including HA alone and HA doped Ca(2+), were performed. It was showed that the adsorption capacity of powdered activated carbon (PAC) for HA was markedly enhanced when Ca(2+) was doped into HA. Also, HA and Ca(2+) taken as nitrate were tested on the uptake of each other respectively and it was showed that the adsorbed amounts of both of them were significantly promoted when HA and calcium co-existed. Furthermore, the adsorbed amount of HA slightly decreased with the increasing of Ca(2+) concentration, whereas the amount of calcium increased with the increasing of HA concentration, but all above the amounts without addition. Finally, the change of pH before and after adsorption process is studied. In the two different solutions including HA alone and HA doped Ca(2+), pH had a small rise, but the extent of pH of later solution was bigger. PMID:25078809

  4. Adsorption of ammonium dinitramide (ADN) from aqueous solutions. 1. Adsorption on powdered activated charcoal.

    PubMed

    Santhosh, G; Venkatachalam, S; Ninan, K N; Sadhana, R; Alwan, S; Abarna, V; Joseph, M A

    2003-03-17

    Investigations on the adsorption of ammonium dinitramide (NH(4)N(NO(2))(2)) (ADN) from aqueous solutions on powdered activated charcoal (PAC) were carried out in order to find out an effective and easier method of separating ADN from aqueous solutions. The effectiveness of PAC in the selective adsorption of ADN from aqueous solutions of ADN (ADN-F) and ADN in presence of sulfate (SO(4)(2-)) and nitrate (NO(3)(-)) ions (ADN-PS) was examined and compared using batch and column methods. The adsorption process follows both Langmuir and Freundlich adsorption isotherms and the isotherm parameters for the models were determined. The observed data favor the formation of monolayer adsorption. The adsorption capacities were found to be 63.3, 119, 105.3 and 82 mg of ADN per g of PAC for ADN-F (batch), ADN-PS (batch), ADN-F (column) and ADN-PS (column), respectively. Break-through curves for ADN-F and ADN-PS were obtained for the optimization of separation of ADN from aqueous solutions. Elution curves were generated for the desorption of ADN from PAC using hot water as eluent.

  5. Panoramic Dental X-Ray

    MedlinePlus

    ... X-ray? What is Panoramic X-ray? Panoramic radiography , also called panoramic x-ray , is a two- ... Exams Dental Cone Beam CT X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety About this Site ...

  6. CTAB-assisted synthesis of mesoporous F-N-codoped TiO{sub 2} powders with high visible-light-driven catalytic activity and adsorption capacity

    SciTech Connect

    Xie Yi Zhao Xiujian Li Yuanzhi; Zhao Qingnan; Zhou Xuedong; Yuan Qihua

    2008-08-15

    This article describes the preparation of mesoporous rod-like F-N-codoped TiO{sub 2} powder photocatalysts with anatase phase via a sol-gel route at the temperature of 373 K, using cetyltrimethyl ammonium bromide (CTAB) as surfactant. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectra (UV-vis DRS). The results showed that the photocatalysts possessed a homogeneous pore diameter and a high surface area of 106.3-160.7 m{sup 3} g{sup -1}. The increasing CTAB reactive concentration extended the visible-light absorption up to 600 nm. The F-N-codoped TiO{sub 2} powders exhibited significant higher adsorption capacity for methyl orange (MO) than that of Degussa P25 and showed more than 6 times higher visible-light-induced catalytic degradation for MO than that of P25. - Graphical abstract: The introduction of surfactant CTAB not only extended the visible light absorption of mesoporous F-N-codoped TiO{sub 2} up to 600 nm but also significantly enhanced the adsorption capacity and visible-light-induced degradation for methyl orange. Mesoporous rod-like F-N-codoped TiO{sub 2} powder photocatalysts were synthesized via a sol-gel route at low temperature of 373 K.

  7. Strengthened lithium for x-ray blast windows

    SciTech Connect

    Pereira, N. R.; Imam, M. A.

    2008-05-15

    Lithium's high x-ray transparency makes it an attractive material for windows intended to protect soft x-ray diagnostics in high energy density experiments. Pure lithium is soft and weak, but lithium mixed with lithium hydride powder becomes harder and stronger, in principle without any additional x-ray absorption. A comparison with the standard material for x-ray windows, beryllium, suggests that lithium or lithium strengthened by lithium hydride may well be an excellent option for such windows.

  8. Strengthened lithium for x-ray blast windows.

    PubMed

    Pereira, N R; Imam, M A

    2008-05-01

    Lithium's high x-ray transparency makes it an attractive material for windows intended to protect soft x-ray diagnostics in high energy density experiments. Pure lithium is soft and weak, but lithium mixed with lithium hydride powder becomes harder and stronger, in principle without any additional x-ray absorption. A comparison with the standard material for x-ray windows, beryllium, suggests that lithium or lithium strengthened by lithium hydride may well be an excellent option for such windows.

  9. X-ray binaries

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Satellite X-ray experiments and ground-based programs aimed at observation of X-ray binaries are discussed. Experiments aboard OAO-3, OSO-8, Ariel 5, Uhuru, and Skylab are included along with rocket and ground-based observations. Major topics covered are: Her X-1, Cyg X-3, Cen X-3, Cyg X-1, the transient source A0620-00, other possible X-ray binaries, and plans and prospects for future observational programs.

  10. Powder-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2016-05-03

    A powder-based adsorbent and a related method of manufacture are provided. The powder-based adsorbent includes polymer powder with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the powder-based adsorbent includes irradiating polymer powder, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Powder-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  11. Development of x-ray laminography under an x-ray microscopic condition

    SciTech Connect

    Hoshino, Masato; Uesugi, Kentaro; Takeuchi, Akihisa; Suzuki, Yoshio; Yagi, Naoto

    2011-07-15

    An x-ray laminography system under an x-ray microscopic condition was developed to obtain a three-dimensional structure of laterally-extended planar objects which were difficult to observe by x-ray tomography. An x-ray laminography technique was introduced to an x-ray transmission microscope with zone plate optics. Three prototype sample holders were evaluated for x-ray imaging laminography. Layered copper grid sheets were imaged as a laminated sample. Diatomite powder on a silicon nitride membrane was measured to confirm the applicability of this method to non-planar micro-specimens placed on the membrane. The three-dimensional information of diatom shells on the membrane was obtained at a spatial resolution of sub-micron. Images of biological cells on the membrane were also obtained by using a Zernike phase contrast technique.

  12. X-ray beamsplitter

    DOEpatents

    Ceglio, N.M.; Stearns, D.G.; Hawryluk, A.M.; Barbee, T.W. Jr.

    1987-08-07

    An x-ray beamsplitter which splits an x-ray beam into two coherent parts by reflecting and transmitting some fraction of an incident beam has applications for x-ray interferometry, x-ray holography, x-ray beam manipulation, and x-ray laser cavity output couplers. The beamsplitter is formed of a wavelength selective multilayer thin film supported by a very thin x-ray transparent membrane. The beamsplitter resonantly transmits and reflects x-rays through thin film interference effects. A thin film is formed of 5--50 pairs of alternate Mo/Si layers with a period of 20--250 A. The support membrane is 10--200 nm of silicon nitride or boron nitride. The multilayer/support membrane structure is formed across a window in a substrate by first forming the structure on a solid substrate and then forming a window in the substrate to leave a free-standing structure over the window. 6 figs.

  13. X-ray beamsplitter

    DOEpatents

    Ceglio, Natale M.; Stearns, Daniel S.; Hawryluk, Andrew M.; Barbee, Jr., Troy W.

    1989-01-01

    An x-ray beamsplitter which splits an x-ray beam into two coherent parts by reflecting and transmitting some fraction of an incident beam has applications for x-ray interferometry, x-ray holography, x-ray beam manipulation, and x-ray laser cavity output couplers. The beamsplitter is formed of a wavelength selective multilayer thin film supported by a very thin x-ray transparent membrane. The beamsplitter resonantly transmits and reflects x-rays through thin film interference effects. A thin film is formed of 5-50 pairs of alternate Mo/Si layers with a period of 20-250 A. The support membrane is 10-200 nm of silicon nitride or boron nitride. The multilayer/support membrane structure is formed across a window in a substrate by first forming the structure on a solid substrate and then forming a window in the substrate to leave a free-standing structure over the window.

  14. X-ray Spectrometry.

    ERIC Educational Resources Information Center

    Markowicz, Andrzej A.; Van Grieken, Rene E.

    1984-01-01

    Provided is a selective literature survey of X-ray spectrometry from late 1981 to late 1983. Literature examined focuses on: excitation (photon and electron excitation and particle-induced X-ray emission; detection (wavelength-dispersive and energy-dispersive spectrometry); instrumentation and techniques; and on such quantitative analytical…

  15. X-ray

    MedlinePlus

    ... is very low. Most experts feel that the benefits of appropriate x-ray imaging greatly outweigh any risks. Young children and babies in the womb are more sensitive to the risks of x-rays. Tell your health care provider if you think you might be pregnant.

  16. X-ray generator

    DOEpatents

    Dawson, John M.

    1976-01-01

    Apparatus and method for producing coherent secondary x-rays that are controlled as to direction by illuminating a mixture of high z and low z gases with an intense burst of primary x-rays. The primary x-rays are produced with a laser activated plasma, and these x-rays strip off the electrons of the high z atoms in the lasing medium, while the low z atoms retain their electrons. The neutral atoms transfer electrons to highly excited states of the highly striped high z ions giving an inverted population which produces the desired coherent x-rays. In one embodiment, a laser, light beam provides a laser spark that produces the intense burst of coherent x-rays that illuminates the mixture of high z and low z gases, whereby the high z atoms are stripped while the low z ones are not, giving the desired mixture of highly ionized and neutral atoms. To this end, the laser spark is produced by injecting a laser light beam, or a plurality of beams, into a first gas in a cylindrical container having an adjacent second gas layer co-axial therewith, the laser producing a plasma and the intense primary x-rays in the first gas, and the second gas containing the high and low atomic number elements for receiving the primary x-rays, whereupon the secondary x-rays are produced therein by stripping desired ions in a neutral gas and transfer of electrons to highly excited states of the stripped ions from the unionized atoms. Means for magnetically confining and stabilizing the plasma are disclosed for controlling the direction of the x-rays.

  17. Clay sized fraction and powdered whole-rock X-ray analyses from alluvial basin deposits in central and southern New Mexico

    USGS Publications Warehouse

    Anderholm, S.K.

    1985-01-01

    As part of the study of the water quality and geochemistry of Southwest Alluvial Basins (SWAB) in parts of Colorado, New Mexico, and Texas, which is a Regional Aquifer-System Analysis (RASA) program, whole rock x-ray analysis and clay-size fraction mineralogy (x-ray) analysis of selected samples from alluvial basin deposits were done to investigate the types of minerals and clay types present in the aquifers. This was done to determine the plausible minerals and clay types in the aquifers that may be reacting with groundwater and affecting the water quality. The purpose of this report is only to present the whole rock x-ray and clay-fraction mineralogy data. Nineteen surface samples or samples from outcrop of Tertiary and Quaternary alluvial basin deposits in the central and southern Rio Grande rift were collected and analyzed. The analysis of the samples consisted of grain size analysis, and clay-size fraction mineralogy and semiquantitative analysis of the relative abundance of different clay mineral groups present. (USGS)

  18. X-ray crystallography

    NASA Technical Reports Server (NTRS)

    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.

  19. Laboratory x ray lasers

    NASA Astrophysics Data System (ADS)

    Matthews, D. L.

    1989-08-01

    One of the most innovative spinoffs of ICF technology and physics was the development of the x ray wavelength laser. The first incontrovertible demonstration of this type of laser came from LLNL in 1984 using the Novette laser to pump a selenium foil target. The power and energy of Novette were then needed to produce a column of plasma of sufficient length to achieve a sufficient gainlength product (approximately 5.5, this corresponds to an amplification of approximately 250X) that could unquestionably illustrate the lasing effect. LLNL ICF expertise was also required to develop time-resolved spectrometers used to view the lasing transitions at approximately 20 nm, a region of the XUV spectrum normally dominated by high backgrounds. The design of the x ray laser amplifier, which required maintaining nonequilibrium level populations in a tailored plasma having the proper conditions for gain and x ray laser beam propagation, was accomplished with modified versions of ICF kinetics and hydrodynamics codes. Since the first demonstration, progress in the development of the x ray laser was rapid. New achievements include production of megawatt power levels at 20 nm, amplified spontaneous emission levels approaching saturation intensity GL of approximately 17 at 20 nm, efficiency (x ray laser energy/pump energy) approximately 10(exp 6), the demonstration of double and triple pass amplification (hinting at the possibility of producing x ray wavelength resonators), the focusing of x ray lasers to pump other types of lasers and the first demonstration of an x ray hologram produced by an x ray laser. The generation of amplification at ever shorter wavelength is possible using various types of inversion schemes. We depict below this progress benchmarked against production of gain in the water window (2.2 to 4.4 nm,), where applications to biological imaging may be facilitated.

  20. Lumbosacral spine x-ray

    MedlinePlus

    X-ray - lumbosacral spine; X-ray - lower spine ... The test is done in a hospital x-ray department or your health care provider's office by an x-ray technician. You will be asked to lie on the x-ray table ...

  1. X-ray laser

    DOEpatents

    Nilsen, Joseph

    1991-01-01

    An X-ray laser (10) that lases between the K edges of carbon and oxygen, i.e. between 44 and 23 Angstroms, is provided. The laser comprises a silicon (12) and dysprosium (14) foil combination (16) that is driven by two beams (18, 20) of intense line focused (22, 24) optical laser radiation. Ground state nickel-like dysprosium ions (34) are resonantly photo-pumped to their upper X-ray laser state by line emission from hydrogen-like silicon ions (32). The novel X-ray laser should prove especially useful for the microscopy of biological specimens.

  2. Correlation between Charge State of Insulating NaCl Surfaces and Ionic Mobility Induced by Water Adsorption: A Combined Ambient Pressure X-ray Photoelectron Spectroscopy and Scanning Force Microscopy Study

    SciTech Connect

    Verdaguer, Albert; Jose Segura, Juan; Fraxedas, Jordi; Bluhm, Hendrik; Salmeron, Miquel

    2008-09-03

    In situ ambient pressure X-ray photoelectron spectroscopy (APPES) and scanning force microscopy were used to characterize the surface discharge induced by water layers grown on (001) surfaces of sodium chloride single crystals. The APPES studies show that both kinetic energy (KE) and full width at half-maximum (FWHM) of the Na 2s and Cl 2p core level peaks, monitored as a function of relative humidity (RH), mimic surface conductivity curves measured using scanning force microscopy. The KE position and FWHM of the core level peaks therefore are directly related to the solvation and diffusion of ions at the NaCl(100) surface upon adsorption of water.

  3. Hard X-Ray Emission from X-Ray Bursters

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.; Kaaret, Philip

    1999-01-01

    The scientific goal of this project is to study the hard x-ray emission from x-ray bursters. One target of opportunity observation was made for this investigation during 1997. We obtained 38ks of data on the source 4UI705-44. The project is closely related to "Monitoring x-ray emission from x-ray bursters", and "Long-Term Hard X-Ray Monitoring of X-Ray Bursters."

  4. N,N-Di- n-octyl- N,N-dimethyl and N,N-di- n-nonyl- N,N-dimethyl ammonium cholates: 13C and 15N CPMAS NMR, powder X-ray diffraction and thermoanalytical characterization

    NASA Astrophysics Data System (ADS)

    Kolehmainen, Erkki; Lahtinen, Manu; Valkonen, Arto; Behera, Babita; Kauppinen, Reijo

    2009-07-01

    N,N-Di- n-octyl- N,N-dimethyl cholate ( 1) and N,N-di- n-nonyl- N,N-dimethyl ammonium cholate ( 2) have been prepared by crystallization from equimolar mixtures of sodium cholate and quaternary N,N-di- n-alkyl- N,N-dimethyl ( n-octyl or n-nonyl) ammonium bromides. The formed crystalline materials have been structurally characterized by 13C and 15N cross polarization magic angle spinning (CPMAS) NMR, powder X-ray diffraction (PXRD) and thermoanalytical (TGA/DTA and DSC) methods and compared with each other. Powder X-ray diffraction patterns of 1 and 2 reveal clear similarities. Combined with the thermoanalytical data of these structures an existence of two hydrated polymorphs (most probably mono- and dihydrates) can be proposed. This presumption is further supported by 13C CPMAS NMR showing clearly double resonances for the carboxylic and majority of other carbons in these quaternary ammonium cholates. Owing to the endogenous character of cholate anion these ionic structures possess great potential in many pharmaceutical applications such as controlled drug delivery.

  5. X-ray (image)

    MedlinePlus

    ... a form of electromagnetic radiation, just like visible light. Structures that are dense (such as bone) will block most of the x-ray particles, and will appear white. Metal and contrast media (special dye used to highlight ...

  6. Pelvis x-ray

    MedlinePlus

    X-ray - pelvis ... Tumors Degenerative conditions of bones in the hips, pelvis, and upper legs ... hip joint Tumors of the bones of the pelvis Sacroiliitis (inflammation of the area where the sacrum ...

  7. Medical X-Rays

    MedlinePlus

    ... Diagnostic X-Ray Equipment Compliance Program Guidance Manual CP 7386.003 Field Compliance Testing of Diagnostic (Medical) ... and Exporting Electronic Products Compliance Program Guidance Manual CP 7386.003 Field Compliance Testing of Diagnostic (Medical) ...

  8. X-ray - skeleton

    MedlinePlus

    ... is used to look for: Fractures or broken bone Cancer that has spread to other areas of the ... 2014:chap 8. Read More Bone tumor Broken bone Cancer Metastasis Osteomyelitis X-ray Update Date 5/9/ ...

  9. Cosmic x ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, Dan; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1992-01-01

    This final report covers the period 1 January 1985 - 31 March 1992. It is divided into the following sections: the soft x-ray background; proportional counter and filter calibrations; sounding rocket flight preparations; new sounding rocket payload: x-ray calorimeter; and theoretical studies. Staff, publications, conference proceedings, invited talks, contributed talks, colloquia and seminars, public service lectures, and Ph. D. theses are listed.

  10. Watching adsorption and electron beam induced decomposition on the model system Mo(CO)6/Cu(1 1 1) by X-ray absorption and photoemission spectroscopies

    NASA Astrophysics Data System (ADS)

    Paufert, Pierre; Fonda, Emiliano; Li, Zheshen; Domenichini, Bruno; Bourgeois, Sylvie

    2013-11-01

    An in-depth study of the first steps of electron beam assisted growth of Mo from molybdenum hexacarbonyl on Cu(1 1 1) has been carried out exploiting the complementarity of X-ray photoemission and X-ray absorption spectroscopies. Frank van der Merwe (2D) growth mode has been observed for the completion of the two first monolayers of adsorbed molecules through a simple physisorption process. Irradiation of the Mo(CO)6 deposit by 1 keV electron beam induces a modification of molybdenum coordination, the average number of C-neighbors decreasing from 6 to 3. Decomposed molecules remain on the surface after annealing at 520 K and organize themselves, the molybdenum atoms moving in Cu(1 1 1) surface fcc hollow sites. After annealing at 670 K, metallic molybdenum growth begins, if the total amount of adsorbed Mo atoms exceeds 1.2 monolayers.

  11. Cation substitution in synthetic meridianiite (MgSO4·11H2O) I: X-ray powder diffraction analysis of quenched polycrystalline aggregates

    NASA Astrophysics Data System (ADS)

    Fortes, A. Dominic; Browning, Frank; Wood, Ian G.

    2012-05-01

    Meridianiite, MgSO4·11H2O, is the most highly hydrated phase in the binary MgSO4-H2O system. Lower hydrates in the MgSO4-H2O system have end-member analogues containing alternative divalent metal cations (Ni2+, Zn2+, Mn2+, Cu2+, Fe2+, and Co2+) and exhibit extensive solid solution with MgSO4 and with one another, but no other undecahydrate is known. We have prepared aqueous MgSO4 solutions doped with these other cations in proportions up to and including the pure end-members. These liquids have been solidified into fine-grained polycrystalline blocks of metal sulfate hydrate + ice by rapid quenching in liquid nitrogen. The solid products have been characterised by X-ray powder diffraction, and the onset of partial melting has been quantified using a thermal probe. We have established that of the seven end-member metal sulfates studied, only MgSO4 forms an undecahydrate; ZnSO4 forms an orthorhombic heptahydrate (synthetic goslarite), MnSO4, FeSO4, and CoSO4 form monoclinic heptahydrates (syn. mallardite, melanterite, bieberite, respectively), and CuSO4 crystallises as the well-known triclinic pentahydrate (syn. chalcanthite). NiSO4 forms a new hydrate which has been indexed with a triclinic unit cell of dimensions a = 6.1275(1) Å, b = 6.8628(1) Å, c = 12.6318(2) Å, α = 92.904(2)°, β = 97.678(2)°, and γ = 96.618(2)°. The unit-cell volume of this crystal, V = 521.74(1) Å3, is consistent with it being an octahydrate, NiSO4·8H2O. Further analysis of doped specimens has shown that synthetic meridianiite is able to accommodate significant quantities of foreign cations in its structure; of the order 50 mol. % Co2+ or Mn2+, 20-30 mol. % Ni2+ or Zn2+, but less than 10 mol. % of Cu2+ or Fe2+. In three of the systems we examined, an `intermediate' phase occurred that differed in hydration state both from the Mg-bearing meridianiite end-member and the pure dopant end-member hydrate. In the case of CuSO4, we observed a melanterite-structured heptahydrate at Cu

  12. Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres

    NASA Astrophysics Data System (ADS)

    Hoffman, A. S.; Debefve, L. M.; Bendjeriou-Sedjerari, A.; Ouldchikh, S.; Bare, Simon R.; Basset, J.-M.; Gates, B. C.

    2016-07-01

    X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities—to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions—to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported.

  13. Dehydrogenation kinetics of air-exposed MgH2/Mg2Cu and MgH2/MgCu2 studied with in situ X-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Andreasen, A.; Sørensen, M. B.; Burkarl, R.; Møller, B.; Molenbroek, A. M.; Pedersen, A. S.; Vegge, T.; Jensen, T. R.

    2006-02-01

    The dehydrogenation kinetics of air exposed samples of MgH2/Mg2Cu and MgH2/MgCu2 have been studied with in situ time resolved X-ray powder diffraction. The X-ray setup enabled the recording of full diffraction patterns within 150 s, thereby allowing the study of structural changes combined with simultaneous extraction of kinetic parameters. Phase fractions as a function of time and temperature were derived from series of consecutive diffraction patterns by numerical integration of selected diffraction peaks. The apparent activation energy for the dehydrogenation of the MgH2/Mg2Cu, and MgH2/MgCu2 sample was found to be 108 kJ/mol and 160 kJ/mol, respectively. Furthermore, substantially improved dehydrogenation kinetics of MgH2 and resistance towards oxidation of Mg due to the presence of Mg2Cu/MgCu2 are discussed in relation to previous work.

  14. X-ray beam finder

    DOEpatents

    Gilbert, H.W.

    1983-06-16

    An X-ray beam finder for locating a focal spot of an X-ray tube includes a mass of X-ray opaque material having first and second axially-aligned, parallel-opposed faces connected by a plurality of substantially identical parallel holes perpendicular to the faces and a film holder for holding X-ray sensitive film tightly against one face while the other face is placed in contact with the window of an X-ray head.

  15. Vacancy-induced nanoscale phase separation in KxFe2–ySe₂ single crystals evidenced by Raman scattering and powder x-ray diffraction

    SciTech Connect

    Lazarević, N.; Abeykoon, M.; Stephens, P. W.; Lei, Hechang; Bozin, E. S.; Petrovic, C.; Popović, Z. V.

    2012-08-06

    Polarized Raman scattering spectra of KxFe2–ySe₂ were analyzed in terms of peculiarities of both I4/m and I4/mmm space group symmetries. The presence of the Raman active modes from both space group symmetries (16 Raman-active modes of the I4/m phase and two Raman-active modes of the I4/mmm phase) confirmed the existence of two crystallographic domains with different space group symmetry in a KxFe2–ySe₂ sample. High-resolution synchrotron powder x-ray diffraction structural refinement of the same sample confirmed the two-phase description, and determined the atomic positions and occupancies for both domains.

  16. Anharmonicity and isomorphic phase transition: a multi-temperature X-ray single-crystal and powder diffraction study of 1-(2′-aminophenyl)-2-methyl-4-nitroimidazole

    PubMed Central

    Poulain, Agnieszka; Wenger, Emmanuel; Durand, Pierrick; Jarzembska, Katarzyna N.; Kamiński, Radosław; Fertey, Pierre; Kubicki, Maciej; Lecomte, Claude

    2014-01-01

    The harmonic model of atomic nuclear motions is usually enough for multipole modelling of high-resolution X-ray diffraction data; however, in some molecular crystals, such as 1-(2′-aminophenyl)-2-methyl-4-nitro-1H-imidazole [Paul, Kubicki, Jelsch et al. (2011 ▶). Acta Cryst. B67, 365–378], it may not be sufficient for a correct description of the charge-density distribution. Multipole refinement using harmonic atom vibrations does not lead to the best electron density model in this case and the so-called ‘shashlik-like’ pattern of positive and negative residual electron density peaks is observed in the vicinity of some atoms. This slight disorder, which cannot be modelled by split atoms, was solved using third-order anharmonic nuclear motion (ANM) parameters. Multipole refinement of the experimental high-resolution X-ray diffraction data of 1-(2′-aminophenyl)-2-methyl-4-nitro-1H-imidazole at three different temperatures (10, 35 and 70 K) and a series of powder diffraction experiments (20 ≤ T ≤ 300 K) were performed to relate this anharmonicity observed for several light atoms (N atoms of amino and nitro groups, and O atoms of nitro groups) to an isomorphic phase transition reflected by a change in the b cell parameter around 65 K. The observed disorder may result from the coexistence of domains of two phases over a large temperature range, as shown by low-temperature powder diffraction. PMID:25075327

  17. High-pressure Powder X-ray Diffraction Study of Cu5Si and Pressure-driven Isostructural Phase Transition

    SciTech Connect

    Li, C.; Yu, Z.; Liu, H.; Lu, T.

    2012-12-03

    The structural behaviour of Cu5Si under high-pressure (HP) has been studied by angular dispersive X-ray diffraction up to 49.9 GPa. The experimental results suggest that a pressure-induced isostructural phase transition occurs around 13.5 GPa as revealed by a discontinuity in volume as a function of pressure. The lattice parameter decreases with the pressure increasing for both low-pressure (LP) and HP phases of Cu5Si. However, a plot of the lattice parameter vs. pressure shows the existence of a plateau between 11.7 and 15.3 GPa. The bulk moduli, derived from the fitting of Birch–Murnaghan equation of state, are 150(2) GPa and 210(3) GPa for the LP phase and the HP phase of Cu5Si, respectively. A change in the electronic state of the copper is assumed to govern the observed structural phase transition.

  18. Ordering, incommensuration, and phase transitions in pyrrhotite. Part II: A high-temperature X-ray powder diffraction and thermomagnetic study

    SciTech Connect

    Li, F.; Franzen, H.F.

    1996-10-01

    High-temperature X-ray diffraction (HTXRD) has been combined with thermomagnetic measurements to study synthetic and natural pyrrhotites. The temperature dependence of the properties observed in DTA, thermomagnetic and diffraction measurements indicates that transitions consistently occur upon heating and cooling so long as the sample is kept below 400{degrees}C, but if the ultimate heating temperature is higher than 550{degrees}C the transitions are altered, probably due to the loss of sulfur. The previously proposed transition sequence for Fe{sub 7}S{sub 8} was supported by HTXRD observation, especially on natural monoclinic pyrrhotite. For intermediate pyrrhotite, the principal ordering was found to be the formation of Kagome nets, and it was found that the vertical stacking sequences that are commensurate along the c axis yield antiferromagnetic characteristics. Based on the changes observed in the HTXRD patterns it is proposed that the mechanism for an observed magnetic {lambda}-transition between the temperatures 150 and 250{degrees}C is the transformation of a commensurate structure with ABCD layering of Kagome nets into a vacancy-disordered structure with the same c modulation.

  19. Polymer adsorption from the melts - In-situ x-ray/neutron reflectivity studies on the chain conformations at the polymer/solid interfaces

    NASA Astrophysics Data System (ADS)

    Jiang, Naisheng; Shang, Jun; Endoh, Maya; Akgun, Bulent; Satija, Sushil; Koga, Tadanori

    2013-03-01

    Adsorbed polymer layers formed on flat solid substrates have recently been the subject of extensive studies due to their strong influence on the physical properties of polymeric materials confined at the nanometer scale. Such adsorbed layers are stable against temperature and solvents and can be formed even onto weakly attractive substrate surfaces. In this study, we aim to clarify the detailed structures and thermal properties by the combined use of in-situ x-ray/neutron reflectivity and atomic force microscopy techniques. Various polymers including polystyrene, polybutadiene, poly (2-vinylpyridine), polycarbonate, and poly(methyl methacrylate) were used to prepare equilibrium adsorbed polymer layers on silicon substrates. We report the effects of the intramolecular architectures, molecular weight, and polymer/substrate interactions on the structures, leading to a better understanding of the thermodynamics at the polymer melt/solid interfaces. We acknowledges the financial support from NSF Grant No. CMMI-084626.

  20. Adsorption and reaction of acetylene on clean and oxygen-precovered Pd(100) studied with high-resolution X-ray photoelectron spectroscopy.

    PubMed

    Höfert, O; Lorenz, M P A; Streber, R; Zhao, W; Bayer, A; Steinrück, H-P; Papp, C

    2013-10-28

    We investigated the adsorption and thermal evolution of acetylene on clean Pd(100) and Pd(100) precovered with 0.25 ML oxygen. The measurements were performed in situ by fast XPS at the synchrotron radiation facility BESSY II. On Pd(100) acetylene molecularly adsorbs at 130 K. Upon heating transformation to a CCH species occurs around 390 K along with the formation of a completely dehydrogenated carbon species. On the oxygen-precovered surface partial CCH formation already occurs upon adsorption at 130 K, and the dehydrogenation temperature and the stability range of CCH are shifted to lower temperatures by ∼200 K. PMID:24182063

  1. Understanding the adsorption mechanism of noble gases Kr and Xe in CPO-27-Ni, CPO-27-Mg, and ZIF-8.

    PubMed

    Magdysyuk, O V; Adams, F; Liermann, H-P; Spanopoulos, I; Trikalitis, P N; Hirscher, M; Morris, R E; Duncan, M J; McCormick, L J; Dinnebier, R E

    2014-11-21

    An experimental study of Xe and Kr adsorption in metal-organic frameworks CPO-27-Ni, CPO-27-Mg, and ZIF-8 was carried out. In situ synchrotron X-ray powder diffraction experiments allowed precise determination of the adsorption sites and sequence of their filling with increasing of gas pressure at different temperatures. Structural investigations were used for interpretation of gas adsorption measurements.

  2. X-ray lithography masking

    NASA Technical Reports Server (NTRS)

    Smith, Henry I. (Inventor); Lim, Michael (Inventor); Carter, James (Inventor); Schattenburg, Mark (Inventor)

    1998-01-01

    X-ray masking apparatus includes a frame having a supporting rim surrounding an x-ray transparent region, a thin membrane of hard inorganic x-ray transparent material attached at its periphery to the supporting rim covering the x-ray transparent region and a layer of x-ray opaque material on the thin membrane inside the x-ray transparent region arranged in a pattern to selectively transmit x-ray energy entering the x-ray transparent region through the membrane to a predetermined image plane separated from the layer by the thin membrane. A method of making the masking apparatus includes depositing back and front layers of hard inorganic x-ray transparent material on front and back surfaces of a substrate, depositing back and front layers of reinforcing material on the back and front layers, respectively, of the hard inorganic x-ray transparent material, removing the material including at least a portion of the substrate and the back layers of an inside region adjacent to the front layer of hard inorganic x-ray transparent material, removing a portion of the front layer of reinforcing material opposite the inside region to expose the surface of the front layer of hard inorganic x-ray transparent material separated from the inside region by the latter front layer, and depositing a layer of x-ray opaque material on the surface of the latter front layer adjacent to the inside region.

  3. X-ray Spectrometer

    NASA Technical Reports Server (NTRS)

    Porter, F. Scott

    2004-01-01

    The X-ray Spectrometer (XRS) instrument is a revolutionary non-dispersive spectrometer that will form the basis for the Astro-E2 observatory to be launched in 2005. We have recently installed a flight spare X R S microcalorimeter spectrometer at the EBIT-I facility at LLNL replacing the XRS from the earlier Astro-E mission and providing twice the resolution. The X R S microcalorimeter is an x-ray detector that senses the heat deposited by the incident photon. It achieves a high energy resolution by operating at 0.06K and by carefully controlling the heat capacity and thermal conductance. The XRS/EBIT instrument has 32 pixels in a square geometry and achieves an energy resolution of 6 eV at 6 keV, with a bandpass from 0.1 to 12 keV (or more at higher operating temperature). The instrument allows detailed studies of the x-ray line emission of laboratory plasmas. The XRS/EBIT also provides an extensive calibration "library" for the Astro-E2 observatory.

  4. X-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2000-01-01

    Dr. S. N. Zhang has lead a seven member group (Dr. Yuxin Feng, Mr. XuejunSun, Mr. Yongzhong Chen, Mr. Jun Lin, Mr. Yangsen Yao, and Ms. Xiaoling Zhang). This group has carried out the following activities: continued data analysis from space astrophysical missions CGRO, RXTE, ASCA and Chandra. Significant scientific results have been produced as results of their work. They discovered the three-layered accretion disk structure around black holes in X-ray binaries; their paper on this discovery is to appear in the prestigious Science magazine. They have also developed a new method for energy spectral analysis of black hole X-ray binaries; four papers on this topics were presented at the most recent Atlanta AAS meeting. They have also carried Monte-Carlo simulations of X-ray detectors, in support to the hardware development efforts at Marshall Space Flight Center (MSFC). These computation-intensive simulations have been carried out entirely on the computers at UAH. They have also carried out extensive simulations for astrophysical applications, taking advantage of the Monte-Carlo simulation codes developed previously at MSFC and further improved at UAH for detector simulations. One refereed paper and one contribution to conference proceedings have been resulted from this effort.

  5. Monitoring X-Ray Emission from X-Ray Bursters

    NASA Technical Reports Server (NTRS)

    Kaaret, Philip

    1998-01-01

    The goal of this investigation was to use the All-Sky Monitor on the Rossi X-Ray Timing Explorer (RXTE) in combination with the Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory to simultaneously measure the x-ray (2-12 keV) and hard x-ray (20-100 keV) emission from x-ray bursters. The investigation was successful. We made the first simultaneous measurement of hard and soft x-ray emission and found a strong anticorrelation of hard and soft x-ray emission from the X-Ray Burster 4U 0614+091. The monitoring performed under this investigation was also important in triggering target of opportunity observations of x-ray bursters made under the investigation hard x-ray emission of x-ray bursters approved for RXTE cycles 1 and 2. These observations lead to a number of papers on high-frequency quasi-periodic oscillations and on hard x-ray emission from the x-ray bursters 4U 0614+091 and 4U 1705-44.

  6. High temperature phase stability in Li{sub 0.12}Na{sub 0.88}NbO{sub 3}: A combined powder X-ray and neutron diffraction study

    SciTech Connect

    Mishra, S. K.; Krishna, P. S. R.; Shinde, A. B.; Jayakrishnan, V. B.; Mittal, R.; Sastry, P. U.; Chaplot, S. L.

    2015-09-07

    The phase stabilities of ecofriendly piezoelectric material of lithium doped sodium niobate for composition Li{sub 0.12}Na{sub 0.88}NbO{sub 3} (LNN12) have been investigated by a combination of powder X-ray and neutron diffraction techniques in the temperature range of 300–1100 K. We observed interesting changes with appearance or disappearance of the super-lattice reflections in the powder diffraction patterns. Unambiguous experimental evidence is shown for coexistence of paraelectric and ferroelectric orthorhombic phases in the temperature range of 525 K to 675 K. We identified the correct crystal structure of LNN12 with temperature and correlated it with observed anomaly in the physical properties. Identification of crystal structure also helps in the mode assignments in Raman and infrared spectroscopies. We argued that application of chemical pressure as a result of Li substitution in NaNbO{sub 3} matrix favors the freezing of zone centre phonons in contrast to the freezing of zone boundary phonons in pure NaNbO{sub 3} with the variation of temperature.

  7. Synthetic, spectral, thermal and powder X-ray diffraction studies of bis(O-alkyldithiocarbonato-S,S‧) antimony(III) dialkyldithiocarbamates

    NASA Astrophysics Data System (ADS)

    Chauhan, H. P. S.; Joshi, Sapana; Carpenter, Jaswant

    2015-02-01

    Compounds of antimony(III) with mixed sulfur donor ligands of the type [(ROCS2)2SbS2CNR‧2] (where, R = C2H5, and iC3H7; R‧ = CH3, C2H5, and CH2CH2) have been synthesized using anhydrous acetone as a solvent by the one pot reaction of antimony(III) tris(O-alkyldithiocarbonato-S,S‧), antimony(III) chloride and sodium/ammonium salt of dialkyldithiocarbamate in 2:1:3 molar ratios. These compounds have been characterized by physicochemical [melting points, molecular weight determinations, elemental analyses (C, H, N, S, and Sb)], spectral [UV, IR, Far-IR and NMR (1H and 13C)] studies. In IR spectra strong band was observed at 1028-1051 cm-1 which indicates anisobidentate mode of bonding of both the ligands with antimony metal. NMR spectral data of these compounds show expected proton resonance due to corresponding moieties. The powder XRD, ESI-Mass and thermal (TG and DTA) studies have also been performed to get the information about geometrical parameters, fragmentation pattern and last thermal decomposition product, respectively. The powder XRD studies lead to the structural properties of the synthesized compounds and show the nanorange crystallite size and monoclinic crystal system. Thermal data of these compounds indicate the formation of antimony sulfide (Sb2S3) as a final thermal degradation product which is used in a number of ways like switching devices television cameras and microwave devices.

  8. Fluctuation X-Ray Scattering

    SciTech Connect

    Saldin, PI: D. K.; Co-I's: J. C. H. Spence and P. Fromme

    2013-01-25

    The work supported by the grant was aimed at developing novel methods of finding the structures of biomolecules using x-rays from novel sources such as the x-ray free electron laser and modern synchrotrons

  9. Dual X-ray absorptiometry

    NASA Astrophysics Data System (ADS)

    Altman, Albert; Aaron, Ronald

    2012-07-01

    Dual X-ray absorptiometry is widely used in analyzing body composition and imaging. Both the method and its limitations are related to the Compton and photoelectric contributions to the X-ray attenuation coefficients of materials.

  10. Modeling high adsorption capacity and kinetics of organic macromolecules on super-powdered activated carbon.

    PubMed

    Matsui, Yoshihiko; Ando, Naoya; Yoshida, Tomoaki; Kurotobi, Ryuji; Matsushita, Taku; Ohno, Koichi

    2011-02-01

    The capacity to adsorb natural organic matter (NOM) and polystyrene sulfonates (PSSs) on small particle-size activated carbon (super-powdered activated carbon, SPAC) is higher than that on larger particle-size activated carbon (powdered-activated carbon, PAC). Increased adsorption capacity is likely attributable to the larger external surface area because the NOM and PSS molecules do not completely penetrate the adsorbent particle; they preferentially adsorb near the outer surface of the particle. In this study, we propose a new isotherm equation, the Shell Adsorption Model (SAM), to explain the higher adsorption capacity on smaller adsorbent particles and to describe quantitatively adsorption isotherms of activated carbons of different particle sizes: PAC and SPAC. The SAM was verified with the experimental data of PSS adsorption kinetics as well as equilibrium. SAM successfully characterized PSS adsorption isotherm data for SPACs and PAC simultaneously with the same model parameters. When SAM was incorporated into an adsorption kinetic model, kinetic decay curves for PSSs adsorbing onto activated carbons of different particle sizes could be simultaneously described with a single kinetics parameter value. On the other hand, when SAM was not incorporated into such an adsorption kinetic model and instead isotherms were described by the Freundlich model, the kinetic decay curves were not well described. The success of the SAM further supports the adsorption mechanism of PSSs preferentially adsorbing near the outer surface of activated carbon particles. PMID:21172719

  11. Tunable X-ray source

    DOEpatents

    Boyce, James R.

    2011-02-08

    A method for the production of X-ray bunches tunable in both time and energy level by generating multiple photon, X-ray, beams through the use of Thomson scattering. The method of the present invention simultaneously produces two X-ray pulses that are tunable in energy and/or time.

  12. X-ray Crystallography Facility

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Edward Snell, a National Research Council research fellow at NASA's Marshall Space Flight Center (MSFC), prepares a protein crystal for analysis by x-ray crystallography as part of NASA's structural biology program. The small, individual crystals are bombarded with x-rays to produce diffraction patterns, a map of the intensity of the x-rays as they reflect through the crystal.

  13. High-pressure synthesis and X-ray powder structure determination of the nitridophosphate BaP{sub 2}N{sub 4}

    SciTech Connect

    Karau, Friedrich W.; Schnick, Wolfgang . E-mail: wolfgang.schnick@uni-muenchen.de

    2005-01-15

    The novel nitridophosphate BaP{sub 2}N{sub 4} was obtained by means of high-pressure high-temperature synthesis utilizing the multianvil technique (8GPa, 1400 deg. C). The [PN{sub 2}]{sup -} network is isoelectronic with silica. The structure was solved from synchrotron powder data by a combination of direct methods and difference Fourier synthesis and refined using the Rietveld method (BaP{sub 2}N{sub 4},Pa3-bar ,Z=12,a=10.22992(2)A). BaP{sub 2}N{sub 4} is isotypic with BaGa{sub 2}S{sub 4},BaAl{sub 2}S{sub 4} and the high-pressure phase of CaB{sub 2}O{sub 4}. The P31 solid-state NMR yielded a single sharp resonance at 0.4ppm.

  14. Synthetic, spectral, thermal and powder X-ray diffraction studies of bis(O-alkyldithiocarbonato-S,S') antimony(III) dialkyldithiocarbamates.

    PubMed

    Chauhan, H P S; Joshi, Sapana; Carpenter, Jaswant

    2015-02-01

    Compounds of antimony(III) with mixed sulfur donor ligands of the type [(ROCS2)2SbS2CNR'2] (where, R=C2H5, and (i)C3H7; R'=CH3, C2H5, and CH2CH2) have been synthesized using anhydrous acetone as a solvent by the one pot reaction of antimony(III) tris(O-alkyldithiocarbonato-S,S'), antimony(III) chloride and sodium/ammonium salt of dialkyldithiocarbamate in 2:1:3molar ratios. These compounds have been characterized by physicochemical [melting points, molecular weight determinations, elemental analyses (C, H, N, S, and Sb)], spectral [UV, IR, Far-IR and NMR ((1)H and (13)C)] studies. In IR spectra strong band was observed at 1028-1051cm(-1) which indicates anisobidentate mode of bonding of both the ligands with antimony metal. NMR spectral data of these compounds show expected proton resonance due to corresponding moieties. The powder XRD, ESI-Mass and thermal (TG and DTA) studies have also been performed to get the information about geometrical parameters, fragmentation pattern and last thermal decomposition product, respectively. The powder XRD studies lead to the structural properties of the synthesized compounds and show the nanorange crystallite size and monoclinic crystal system. Thermal data of these compounds indicate the formation of antimony sulfide (Sb2S3) as a final thermal degradation product which is used in a number of ways like switching devices television cameras and microwave devices.

  15. Adsorption of clofibric acid and ketoprofen onto powdered activated carbon: effect of natural organic matter.

    PubMed

    Gao, Yaohuan; Deshusses, Marc A

    2011-12-01

    The adsorption of two acidic pharmaceutically active compounds (PhACs), clofibric acid and ketoprofen, onto powdered activated carbon (PAC) was investigated with a particular focus on the influence of natural organic matter (NOM) on the adsorption of the PhACs. Suwannee River humic acids (SRHAs) were used as a substitute for NOM. Batch adsorption experiments were conducted to obtain adsorption kinetics and adsorption isotherms with and without SRHAs in the system. The adsorption isotherms and adsorption kinetics showed that the adsorption ofclofibric acid was not significantly affected by the presence of SRHAs at a concentration of 5 mg (as carbon) L(-1). An adsorption capacity of 70 to 140 mg g(-1) was observed and equilibrium was reached within 48 h. In contrast, the adsorption of ketoprofen was markedly decreased (from about 120 mg g(-1) to 70-100 mg g(-1)) in the presence of SRHAs. Higher initial concentrations of clofibric acid than ketoprofen during testing may explain the different behaviours that were observed. Also, the more hydrophobic ketoprofen molecules may have less affinity for PAC when humic acids (which are hydrophilic) are present. The possible intermolecular forces that could account for the different behaviour of clofibric acid and ketoprofen adsorption onto PAC are discussed. In particular, the relevance of electrostatic forces, electron donor-acceptor interaction, hydrogen bonding and London dispersion forces are discussed PMID:22439557

  16. X-ray satellite

    NASA Technical Reports Server (NTRS)

    1985-01-01

    An overview of the second quarter 1985 development of the X-ray satellite project is presented. It is shown that the project is proceeding according to plan and that the projected launch date of September 9, 1987 is on schedule. An overview of the work completed and underway on the systems, subsystems, payload, assembly, ground equipment and interfaces is presented. Problem areas shown include cost increases in the area of focal instrumentation, the star sensor light scattering requirements, and postponements in the data transmission subsystems.

  17. SMM x ray polychromator

    NASA Technical Reports Server (NTRS)

    Saba, J. L. R.

    1993-01-01

    The objective of the X-ray Polychromator (XRP) experiment was to study the physical properties of solar flare plasma and its relation to the parent active region to understand better the flare mechanism and related solar activity. Observations were made to determine the temperature, density, and dynamic structure of the pre-flare and flare plasma as a function of wavelength, space and time, the extent to which the flare plasma departs from thermal equilibrium, and the variation of this departure with time. The experiment also determines the temperature and density structure of active regions and flare-induced changes in the regions.

  18. On the estimation of statistical uncertainties on powder diffraction and small-angle scattering data from two-dimensional X-ray detectors

    SciTech Connect

    Yang, X.; Juhás, P.; Billinge, S. J. L.

    2014-07-19

    Optimal methods are explored for obtaining one-dimensional powder pattern intensities from two-dimensional planar detectors with good estimates of their standard deviations. Methods are described to estimate uncertainties when the same image is measured in multiple frames as well as from a single frame. The importance of considering the correlation of diffraction points during the integration and the resampling process of data analysis is shown. It is found that correlations between adjacent pixels in the image can lead to seriously overestimated uncertainties if such correlations are neglected in the integration process. Off-diagonal entries in the variance–covariance (VC) matrix are problematic as virtually all data processing and modeling programs cannot handle the full VC matrix. It is shown that the off-diagonal terms come mainly from the pixel-splitting algorithm used as the default integration algorithm in many popular two-dimensional integration programs, as well as from rebinning and resampling steps later in the processing. When the full VC matrix can be propagated during the data reduction, it is possible to get accurate refined parameters and their uncertainties at the cost of increasing computational complexity. However, as this is not normally possible, the best approximate methods for data processing in order to estimate uncertainties on refined parameters with the greatest accuracy from just the diagonal variance terms in the VC matrix is explored.

  19. CH 3Cl adsorption on a Si(100)2 × 1 surface modified by alkali metal overlayer studied by soft X-ray photoemission using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Gentle, T. M.; Soukiassian, P.; Schuette, K. P.; Bakshi, M. H.; Hurych, Z.

    1988-08-01

    We present the first study of the effect of an alkali metal overlayer on the adsorption of an organic molecule, methylchloride, on a Si(100)2 × 1 surface. In strong contrast to the behavior of molecular oxygen or nitrogen which were found to react with the silicon substrate, there was no significant interaction between methylchloride and silicon, rather, the formation of alkali-chlorine bonds was observed. Core level and valence band spectroscopies using synchrotron radiation were used to study these systems. Sodium was found to exhibit the strongest interaction with mehtylchloride which was dissociated, while the effects produced by K and Cs were weaker.

  20. Ligand K-edge x-ray adsorption spectroscopic studies of the electronic structure of inorganic model complexes and metalloprotein active sites

    NASA Astrophysics Data System (ADS)

    Shadle, S. E.

    1994-08-01

    Ligand K-edge X-ray absorption spectroscopy (XAS) has been developed as a technique for the investigation of ligand-metal bonding and has been applied to the study of electronic structure in organic model complexes and metalloprotein active sites. Ligand K-edge XAS has been measured at the chloride K-edge for a series of complexes containing chloride ligands bound to open shell d(sup 9) copper ions. The intensity of the pre-edge feature in these spectra reflects the covalency in the half-occupied d(sub x)2(sub -y)2-derived molecular orbital (HOMO) of the complex. The energy of the pre-edge feature is related to both the charge on the ligand and the HOMO energy. An analysis of the intensity and energy of the pre-edge feature as well as the energy of the rising edge absorption provides quantitative information about the covalency of the ligand-metal interaction, the charge donated by the chloride, and the energy of the copper d-manifold. The results demonstrate that ligand K-edge XAS features can be used to obtain quantitative information about ligand-metal bonding. The results also identify the chemical basis for trends in the XAS data for the complexes: D(sub 4h)CuCl4(sup 2-), D(sub 2d)CuCl4(sup 2-), planar, trans-CuCl2(pdmp)(sub 2) (pdmp=N-phenyl-3,5-dimethylpyrazole), square pyramidal CuCl5(sup 3-), the planar dimer KCuCl3, the distorted tetrahedral dimer (Ph4P)CuCl3, and two dimers with mixed ligation, one containing a bridging chloride, and the other, terminally bound chloride. A geometric distortion from square planar to distorted tetrahedral results in a decrease in the chloride-copper HOMO covalency but an increase in the total charge donation by the chlorides. Thus, while the geometry can maximize the overlap for a highly covalent HOMO, this does not necessarily reflect the overall charge donation. The Cl-Cu(II) bonding interactions are dependent on the nature of the other coordinating ligands.

  1. Soft x-ray lasers

    SciTech Connect

    Matthews, D.L.; Rosen, M.D.

    1988-12-01

    One of the elusive dreams of laser physicists has been the development of an x-ray laser. After 25 years of waiting, the x-ray laser has at last entered the scientific scene, although those now in operation are still laboratory prototypes. They produce soft x rays down to about five nanometers. X-ray lasers retain the usual characteristics of their optical counterparts: a very tight beam, spatial and temporal coherence, and extreme brightness. Present x-ray lasers are nearly 100 times brighter that the next most powerful x-ray source in the world: the electron synchrotron. Although Lawrence Livermore National Laboratory (LLNL) is widely known for its hard-x-ray laser program which has potential applications in the Strategic Defense Initiative, the soft x-ray lasers have no direct military applications. These lasers, and the scientific tools that result from their development, may one day have a place in the design and diagnosis of both laser fusion and hard x-ray lasers. The soft x-ray lasers now in operation at the LLNL have shown great promise but are still in the primitive state. Once x-ray lasers become reliable, efficient, and economical, they will have several important applications. Chief among them might be the creation of holograms of microscopic biological structures too small to be investigated with visible light. 5 figs.

  2. X-ray lithography source

    DOEpatents

    Piestrup, M.A.; Boyers, D.G.; Pincus, C.

    1991-12-31

    A high-intensity, inexpensive X-ray source for X-ray lithography for the production of integrated circuits is disclosed. Foil stacks are bombarded with a high-energy electron beam of 25 to 250 MeV to produce a flux of soft X-rays of 500 eV to 3 keV. Methods of increasing the total X-ray power and making the cross section of the X-ray beam uniform are described. Methods of obtaining the desired X-ray-beam field size, optimum frequency spectrum and eliminating the neutron flux are all described. A method of obtaining a plurality of station operation is also described which makes the process more efficient and economical. The satisfying of these issues makes transition radiation an excellent moderate-priced X-ray source for lithography. 26 figures.

  3. X-ray lithography source

    DOEpatents

    Piestrup, Melvin A.; Boyers, David G.; Pincus, Cary

    1991-01-01

    A high-intensity, inexpensive X-ray source for X-ray lithography for the production of integrated circuits. Foil stacks are bombarded with a high-energy electron beam of 25 to 250 MeV to produce a flux of soft X-rays of 500 eV to 3 keV. Methods of increasing the total X-ray power and making the cross section of the X-ray beam uniform are described. Methods of obtaining the desired X-ray-beam field size, optimum frequency spectrum and elminating the neutron flux are all described. A method of obtaining a plurality of station operation is also described which makes the process more efficient and economical. The satisfying of these issues makes transition radiation an exellent moderate-priced X-ray source for lithography.

  4. Monitoring X-Ray Emission from X-Ray Bursters

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.; Kaaret, Philip

    1999-01-01

    The scientific goal of this project was to monitor a selected sample of x-ray bursters using data from the All-Sky Monitor (ASM) on the Rossi X-Ray Timing Explorer together with data from the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory to study the long-term temporal evolution of these sources in the x-ray and hard x-ray bands. The project was closely related to "Long-Term Hard X-Ray Monitoring of X-Ray Bursters", NASA project NAG5-3891, and and "Hard x-ray emission of x-ray bursters", NASA project NAG5-4633, and shares publications in common with both of these. The project involved preparation of software for use in monitoring and then the actual monitoring itself. These efforts have lead to results directly from the ASM data and also from Target of Opportunity Observations (TOO) made with the Rossi X-Ray Timing Explorer based on detection of transient hard x-ray outbursts with the ASM and BATSE.

  5. Adsorption of Halogenated Fire-Extinguishing Agents on Powders

    NASA Technical Reports Server (NTRS)

    Barduhn, Allen J.; Patel, Bhailal S.; Meyer, Walter; Smura, Bronislaw B.

    1960-01-01

    The amounts of four different Freons adsorbed by carbon, silica gel, alumina, and molecular sieves were determined at pressures up to 225 lb/sq in. The carbon adsorbed 50 to 100 percent and the silica gels, 30 to 50 percent of their own weight of Freon. Several adsorbed systems were tested in a standard dry-powder extinguisher on a 5-sq-ft gasoline fire for their effectiveness in putting out a fire. One of the Freons (bromotrifluoromethane) and carbon extinguished fires about as well as bicarbonate powder and nitrogen.

  6. Experimental study of germanium adsorption on goethite and germanium coprecipitation with iron hydroxide: X-ray absorption fine structure and macroscopic characterization

    NASA Astrophysics Data System (ADS)

    Pokrovsky, O. S.; Pokrovski, G. S.; Schott, J.; Galy, A.

    2006-07-01

    Adsorption of germanium on goethite was studied at 25 °C in batch reactors as a function of pH (1-12), germanium concentration in solution (10 -7 to 0.002 M) and solid/solution ratio (1.8-17 g/L). The maximal surface site density determined via Ge adsorption experiments at pH from 6 to 10 is equal to 2.5 ± 0.1 μmol/m 2. The percentage of adsorbed Ge increases with pH at pH < 9, reaches a maximum at pH ˜ 9 and slightly decreases when pH is further increased to 11. These results allowed generation of a 2-p K Surface Complexation Model (SCM) which implies a constant capacitance of the electric double layer and postulates the presence of two Ge complexes, >FeO-Ge(OH)30 and >FeO-GeO(OH)2-, at the goethite-solution interface. Coprecipitation of Ge with iron oxy(hydr)oxides formed during Fe(II) oxidation by atmospheric oxygen or by Fe(III) hydrolysis in neutral solutions led to high Ge incorporations in solid with maximal Ge/Fe molar ratio close to 0.5. The molar Ge/Fe ratio in precipitated solid is proportional to that in the initial solution according to the equation (Ge/Fe) solid = k × (Ge/Fe) solution with 0.7 ⩽ k ⩽ 1.0. The structure of adsorbed and coprecipitated Ge complexes was further characterized using XAFS spectroscopy. In agreement with previous data on oxyanions adsorption on goethite, bi-dentate bi-nuclear surface complexes composed of tetrahedrally coordinated Ge attached to the corners of two adjacent Fe octahedra represent the dominant contribution to the EXAFS signal. Coprecipitated samples with Ge/Fe molar ratios >0.1, and samples not aged in solution (<1 day) having intermediate Ge/Fe ratios (0.01-0.1) show 4 ± 0.3 oxygen atoms at 1.76 ± 0.01 Å around Ge. Samples less concentrated in Ge (0.001 < Ge/Fe < 0.10) and aged longer times in solution (up to 280 days) exhibit a splitting of the first atomic shell with Ge in both tetrahedral ( R = 1.77 ± 0.02 Å) and octahedral ( R = 1.92 ± 0.03 Å) coordination with oxygen. In these samples

  7. High-energy X-ray powder diffraction and atomic-pair distribution-function studies of charged/discharged structures in carbon-hybridized Li2MnSiO4 nanoparticles as a cathode material for lithiumion batteries

    SciTech Connect

    Moriya, Maki; Miyahara, Masahiko; Hokazono, Mana; Sasaki, Hirokazu; Nemoto, Atsushi; Katayama, Shingo; Akimoto, Yuji; Hirano, Shin-ichi; Ren, Yang

    2014-10-01

    The stable cycling performance with a high discharge capacity of similar to 190 mAh g(-1) in a carbon-hybridized Li2MnSiO4 nanostructured powder has prompted an experimental investigation of the charged/discharged structures using synchrotron-based and laboratory-based X-rays and atomic-pair distributionfunction (PDF) analyses. A novel method of in-situ spray pyrolysis of a precursor solution with glucose as a carbon source enabled the successful synthesis of the carbon-hybridized Li2(M)nSiO(4) nanoparticles. The XRD patters of the discharged (lithiated) samples exhibit a long-range ordered structure characteristic of the (beta) Li2MnSiO4 crystalline phase (space group Pmn2(1)) which dissipates in the charged (delithiated) samples. However, upon discharging the long-range ordered structure recovers in each cycle. The disordered structure, according to the PDF analysis, is mainly due to local distortions of the MnO4 tetrahedra which show a mean Mn-O nearest neighbor distance shorter than that of the long-range ordered phase. These results corroborate the notion of the smaller Mn3+/Mn4+ ionic radii in the Li extracted phase versus the larger Mn2+ ionic radius in Li inserted phase. Thus Li extraction/insertion drives the fluctuation between the disordered and the long-range ordered structures. (C) 2014 Elsevier B.V. All rights reserved.

  8. Unraveling the Hydrogenation of TiO 2 and Graphene Oxide/TiO 2 Composites in Real Time by in Situ Synchrotron X-ray Powder Diffraction and Pair Distribution Function Analysis

    DOE PAGES

    Nguyen-Phan, Thuy-Duong; Liu, Zongyuan; Luo, Si; Gamalski, Andrew D.; Vovchok, Dimitry; Xu, Wenqian; Stach, Eric A.; Polyansky, Dmitry E.; Fujita, Etsuko; Rodriguez, José A.; et al

    2016-02-18

    The functionalization of graphene oxide (GO) and graphene by TiO2 and other metal oxides has attracted considerable attention due to numerous promising applications in catalysis, energy conversion, and storage. We propose hydrogenation of this class of materials as a promising way to tune catalytic properties by altering the structural and chemical transformations that occur upon H incorporation. We also investigate the structural changes that occur during the hydrogenation process using in situ powder X-ray diffraction and pair distribution function analysis of GO–TiO2 and TiO2 under H2 reduction. Sequential Rietveld refinement was employed to gain insight into the evolution of crystalmore » growth of TiO2 nanoparticles in the presence of two-dimensional (2D) GO nanosheets. GO sheets not only significantly retarded the nucleation and growth of rutile impurities, stabilizing the anatase structure, but was also partially reduced to hydrogenated graphene by the introduction of atomic hydrogen into the honeycomb lattice. We discuss the hydrogenation processes and the resulting composite structure that occurs during the incorporation of atomic H and the dynamic structural transformations that leads to a highly active photocatalyst.« less

  9. Polymorphism of ceramide 3. Part 2: a vibrational spectroscopic and X-ray powder diffraction investigation of N-octadecanoyl phytosphingosine and the analogous specifically deuterated d(35) derivative.

    PubMed

    Raudenkolb, Steve; Wartewig, Siegfried; Neubert, Reinhard H H

    2003-07-01

    In order to characterize the arrangements of the hydrocarbon chains of ceramide 3, the thermotropic phase behaviour of the ceramides N-octadecanoylphytosphingosine (CER3) and its chain deuterated derivative N-(d(35)-octadecanoyl)phytosphingosine (d(35)CER3) was studied by means of X-ray powder diffraction, FT-IR and Raman spectroscopy. CER3 and d(35)CER3 exhibit an identical thermotropic polymorphism involving three different crystalline phases. The selective deuteration of the fatty acid chain enables to distinguish the sphingoid part from the fatty acid part by means of FT-IR and Raman spectroscopy. It could be shown that both hydrocarbon chains are arranged in different subcells. Temperature dependent Raman measurements elucidate simultaneously the changes in the trans/gauche ratios and the packing of both the hydrocarbon chains of the fatty acid and of the sphingoid part. The phase behaviour of CER3 and d(35)CER3, both dry and hydrated, was investigated. PMID:12818735

  10. Refinement of the crystal structure of the high-temperature phase G{sub 0} in (NH{sub 4}){sub 2}WO{sub 2}F{sub 4} (powder, X-ray, and neutron scattering)

    SciTech Connect

    Novak, D. M. Smirnov, L. S.; Kolesnikov, A. I.; Voronin, V. I.; Berger, I. F.; Laptash, N. M.; Vasil'ev, A. D.; Flerov, I. N.

    2013-01-15

    The (NH{sub 4}){sub 2}WO{sub 2}F{sub 4} compound undergoes a series of phase transitions: G{sub 0} {yields} 201, K {yields} G{sub 1} {yields} 160, and K {yields} G{sub 2}, with a significant change in entropy ({Delta}S{sub 1} {approx} Rln10 at the G{sub 0} {yields} G{sub 1} transition), which indicates significant orientational disordering in the G{sub 0} phase and the order-disorder type of the phase transition. X-ray diffraction is used to identify the crystal structure of the G{sub 0} phase as rhombohedral (sp. gr. Cmcm, Z = 4), determine the lattice parameters and the positions of all atoms (except hydrogen), and show that [WO{sub 2}F{sub 4}]{sup 2-} ions can form a superposition of dynamic and static orientational disorders in the anionic sublattice. A determination of the orientational position of [NH{sub 4}]{sup +} ions calls for the combined method of elastic and inelastic neutron scattering. Inelastic neutron scattering is used to determine the state of hindered rotation for ammonium ions in the G{sub 0} phase. Powder neutron diffraction shows that the orientational disorder of NH{sub 4} ions can adequately be described within the free-rotation approximation.

  11. Powder X-ray diffraction, infrared and 13C NMR spectroscopic studies of the homologous series of some solid-state zinc(II) and sodium(I) n-alkanoates

    NASA Astrophysics Data System (ADS)

    Nelson, Peter N.; Taylor, Richard A.

    2015-03-01

    A comparative study of the room temperature molecular packing and lattice structures for the homologous series of zinc(II) and sodium(I) n-alkanoates adduced from Fourier transform infrared and solid-state 13C NMR spectroscopic data in conjunction with X-ray powder diffraction measurements is carried out. For zinc carboxylates, metal-carboxyl bonding is via asymmetric bridging bidentate coordination whilst for the sodium adducts, coordination is via asymmetric chelating bidentate bonding. All compounds are packed in a monoclinic crystal system. Furthermore, the fully extended all-trans hydrocarbon chains are arranged as lamellar bilayers. For zinc compounds, there is bilayer overlap, for long chain adducts (nc > 8) but not for sodium compounds where methyl groups from opposing layers in the lamellar are only closely packed. Additionally, the hydrocarbon chains are extended along the a-axis of the unit cell for zinc compounds whilst for sodium carboxylates they are extended along the c-axis. These packing differences are responsible for different levels of Van der Waals effects in the lattices of these two series of compounds, hence, observed odd-even alternation is different. The significant difference in lattice packing observed for these two series of compounds is proposed to be due to the difference in metal-carboxyl coordination mode, arising from the different electronic structure of the central metal ions.

  12. Refinement of the crystal structure of the high-temperature phase G0 in (NH4)2WO2F4 (powder, x-ray, and neutron scattering)

    SciTech Connect

    Novak, D. M.; Smirnov, Lev S; Kolesnikov, Alexander I; Voronin, Vladimir; Berger, I. F.; Laptash, N. M.; Vasil'ev, N. M.; Flerov, I. N.

    2013-01-01

    The (NH4)2WO2F4 compound undergoes a series of phase transitions: G0 -> 201 K -> G1 -> 160 K -> G2, with a significant change in entropy ( S1 ~ Rln10 at the G0 -> G1 transition), which indicates significant orientational disordering in the G0 phase and the order disorder type of the phase transition. X-ray diffraction is used to identify the crystal structure of the G0 phase as rhombohedral (sp. gr. Cmcm, Z = 4), determine the lattice parameters and the positions of all atoms (except hydrogen), and show that [WO2F4]2 ions can form a superposition of dynamic and static orientational disorders in the anionic sublattice. A determination of the orientational position of [NH4]+ ions calls for the combined method of elastic and inelastic neutron scattering. Inelastic neutron scattering is used to determine the state of hindered rotation for ammonium ions in the G0 phase. Powder neutron diffraction shows that the orientational disorder of NH4 ions can adequately be described within the free rotation approximation.

  13. Hydrogen in polar intermetallics: Syntheses and structures of the ternary Ca5Bi3D0.93, Yb5Bi3Hx, and Sm5Bi3H~1 by powder neutron or single crystal X-ray diffraction

    SciTech Connect

    Leon-Escamilla, E. Alejandro; Dervenagas, Panagiotis; Stasis, Constantine; Corbett, John D.

    2010-01-01

    The syntheses of the title compounds are described in detail. Structural characterizations from refinements of single crystal X-ray diffraction data for Yb{sub 5}Bi{sub 3}H{sub x} and Sm{sub 5}Bi{sub 3}H{sub 1} and of powder neutron diffraction data for Ca{sub 5}Bi{sub 3}D{sub 0.93(3)} are reported. These confirm that all three crystallize with the heavy atom structure type of {beta}-Yb{sub 5}Sb{sub 3}, and the third gives the first proof that the deuterium lies in the center of nominal calcium tetrahedra, isostructural with the Ca{sub 5}Sb{sub 3}F-type structure. These Ca and Yb phases are particularly stable with respect to dissociation to Mn{sub 5}Si{sub 3}-type product plus H{sub 2}. Some contradictions in the literature regarding Yb{sub 5}Sb{sub 3} and Yb{sub 5}Sb{sub 3}H{sub x} phases are considered in terms of adventitious hydrogen impurities that are generated during reactions in fused silica containers at elevated temperatures.

  14. Assessment of the optimum degree of Sr{sub 3}Fe{sub 2}MoO{sub 9} electron-doping through oxygen removal: An X-ray powder diffraction and {sup 57}Fe Moessbauer spectroscopy study

    SciTech Connect

    Lopez, Carlos A.; Viola, Maria del C.; Pedregosa, Jose C.; Mercader, Roberto C.

    2010-10-15

    We describe the preparation and structural characterization by X-ray powder diffraction (XRPD) and Moessbauer spectroscopy of three electron-doped perovskites Sr{sub 3}Fe{sub 2}MoO{sub 9-{delta}} with Fe/Mo = 2 obtained from Sr{sub 3}Fe{sub 2}MoO{sub 9}. The compounds were synthesized by topotactic reduction with H{sub 2}/N{sub 2} (5/95) at 600, 700 and 800 {sup o}C. Above 800 {sup o}C the Fe/Mo ratio changes from Fe/Mo = 2-1 < Fe/Mo < 2. The structural refinements of the XRPD data for the reduced perovskites were carried out by the Rietveld profile analysis method. The crystal structure of these phases is cubic, space group Fm3-bar m, with cationic disorder at the two different B sites that can be populated in variable proportions by the Fe atoms. The Moessbauer spectra allowed determining the evolution of the different species formed after the treatments at different temperatures and confirm that Fe ions in the samples reduced at 600, 700 and 800 {sup o}C are only in the high-spin Fe{sup 3+} electronic state.

  15. Hard X-Ray Emission of X-Ray Bursters

    NASA Technical Reports Server (NTRS)

    Kaaret, P.

    1999-01-01

    The primary goal of this proposal was to perform an accurate measurement of the broadband x-ray spectrum of a neutron-star low-mass x-ray binary found in a hard x-ray state. This goal was accomplished using data obtained under another proposal, which has provided exciting new information on the hard x-ray emission of neutron-star low-mass x-ray binaries. In "BeppoSAX Observations of the Atoll X-Ray Binary 4U0614+091", we present our analysis of the spectrum of 4U0614+091 over the energy band from 0.3-150 keV. Our data confirm the presence of a hard x-ray tail that can be modeled as thermal Comptonization of low-energy photons on electrons having a very high temperature, greater than 220 keV, or as a non-thermal powerlaw. Such a very hard x-ray spectrum has not been previously seen from neutron-star low-mass x-ray binaries. We also detected a spectral feature that can be interpreted as reprocessing, via Compton reflection, of the direct emission by an optically-thick disk and found a correlation between the photon index of the power-law tail and the fraction of radiation reflected which is similar to the correlation found for black hole candidate x-ray binaries and Seyfert galaxies. A secondary goal was to measure the timing properties of the x-ray emission from neutronstar low-mass x-ray binaries in their low/hard states.

  16. Structure determination of. beta. - and. gamma. -BaAIF sub 5 by X-ray and neutron powder diffraction: A model for the. alpha. yields. beta. leftrightarrow. gamma. transitions

    SciTech Connect

    Le Bail, A.; Ferey, G.; Mercier, A.M. ); De Kozak, A.; Samoueel, M. )

    1990-12-01

    {beta}-BaAlF{sub 5} is monoclinic (space group P2{sub 1}/n): a = 5.1517(1) {angstrom}, b = 19.5666(4) {angstrom}, c = 7.5567(2) {angstrom}, {beta} = 92.426(1){degree}, Z = 8. {gamma}-BaAlF{sub 5} is monoclinic (space group P2{sub 1}): a = 5.2584(1) {angstrom}, b = 9.7298(2) {angstrom}, c = 7.3701(2) {angstrom}, {beta} = 90.875(1){degree}, Z = 4. Both structures are determined ab initio from X-ray powder data; final results are given from neutron powder data refinements (R{sub I} = 0.038, R{sub P} = 0.072, and R{sub WP} = 0.087 and R{sub I} = 0.048, R{sub P} = 0.083, and R{sub WP} = 0.101 for the {beta} and {gamma} phases, respectively). Like {alpha}-BaAlF{sub 5}, the {beta} and {gamma} phases are built up from isolated infinite (AlF{sub 5}){sup 2n{minus}}{sub n} chains with AlF{sub 6} octahedra sharing corners in a cis-position. Close structural relationships are shown to exist between the Ba-Al cationic subnetwork of: {alpha}-BaAlF{sub 5} and the CrB-type structure; {beta}-BaAlF{sub 5} and the SrAg-type; {gamma}-BaAlF{sub 5} and the FeB-type.

  17. Solar X-ray physics

    SciTech Connect

    Bornmann, P.L. )

    1991-01-01

    Research on solar X-ray phenomena performed by American scientists during 1987-1990 is reviewed. Major topics discussed include solar images observed during quiescent times, the processes observed during solar flares, and the coronal, interplanetary, and terrestrial phenomena associated with solar X-ray flares. Particular attention is given to the hard X-ray emission observed at the start of the flare, the energy transfer to the soft X-ray emitting plasma, the late resolution of the flare as observed in soft X-ray, and the rate of occurrence of solar flares as a function of time and latitude. Pertinent aspects of nonflaring, coronal X-ray emission and stellar flares are also discussed. 175 refs.

  18. Miniature x-ray source

    DOEpatents

    Trebes, James E.; Stone, Gary F.; Bell, Perry M.; Robinson, Ronald B.; Chornenky, Victor I.

    2002-01-01

    A miniature x-ray source capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature x-ray source comprises a compact vacuum tube assembly containing a cathode, an anode, a high voltage feedthru for delivering high voltage to the anode, a getter for maintaining high vacuum, a connection for an initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is highly x-ray transparent and made, for example, from boron nitride. The compact size and potential for remote operation allows the x-ray source, for example, to be placed adjacent to a material sample undergoing analysis or in proximity to the region to be treated for medical applications.

  19. Quantitative determination of two polymorphic forms of imatinib mesylate in a drug substance and tablet formulation by X-ray powder diffraction, differential scanning calorimetry and attenuated total reflectance Fourier transform infrared spectroscopy.

    PubMed

    Bellur Atici, Esen; Karlığa, Bekir

    2015-10-10

    Imatinib has been identified as a tyrosine kinase inhibitor that selectively inhibits the Abl tyrosine kinases, including Bcr-Abl. The active substance used in drug product is the mesylate salt form of imatinib, a phenylaminopyrimidine derivative and chemically named as N-(3-(4-(pyridin-3-yl) pyrimidin-2-ylamino)-4-methylphenyl)-4-((4-methylpiperazin-1-yl) methyl)-benzamide methanesulfonic acid salt. It exhibits many polymorphic forms and most stable and commercialized polymorphs are known as α and β forms. Molecules in α and β polymorphic forms exhibit significant conformational differences due to their different intra- and intermolecular interactions, which stabilize their molecular conformations and affect their physicochemical properties such as bulk density, melting point, solubility, stability, and processability. The manufacturing process of a drug tablet included granulation, compression, coating, and drying may cause polymorphic conversions. Therefore, polymorphic content of the drug substance should be controlled during quality control and stability testing. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD) methods were evaluated for determination of the polymorphic content of the drug substance and drug product; and PXRD was the most accurate technique and selected as preferred method and validated. Prior to development of a quantification method, pure α and β polymorphs were characterized and used throughout the method development and validation studies. Mixtures with different ratios of α and β forms were scanned using X-ray diffractometer with a scan rate of 0.250°/min over an angular range of 19.5-21.0° 2θ and the peak heights for characteristic peak of β form at 20.5 ± 0.2° 2θ diffraction angle were used to generate a calibration curve. The detection limit of β polymorph in α form imatinib mesylate tablets was found as 4% and

  20. Topological X-Rays Revisited

    ERIC Educational Resources Information Center

    Lynch, Mark

    2012-01-01

    We continue our study of topological X-rays begun in Lynch ["Topological X-rays and MRI's," iJMEST 33(3) (2002), pp. 389-392]. We modify our definition of a topological magnetic resonance imaging and give an affirmative answer to the question posed there: Can we identify a closed set in a box by defining X-rays to probe the interior and without…

  1. X-ray and neutron powder diffraction analyses of Gly·MgSO4·5H2O and Gly·MgSO4·3H2O, and their deuterated counterparts.

    PubMed

    Howard, Christopher; Wood, Ian G; Knight, Kevin S; Fortes, A Dominic

    2016-03-01

    We have identified a new compound in the glycine-MgSO4-water ternary system, namely glycine magnesium sulfate trihydrate (or Gly·MgSO4·3H2O) {systematic name: catena-poly[[tetraaquamagnesium(II)]-μ-glycine-κ(2)O:O'-[diaquabis(sulfato-κO)magnesium(II)]-μ-glycine-κ(2)O:O']; [Mg(SO4)(C2D5NO2)(D2O)3]n}, which can be grown from a supersaturated solution at ∼350 K and which may also be formed by heating the previously known glycine magnesium sulfate pentahydrate (or Gly·MgSO4·5H2O) {systematic name: hexaaquamagnesium(II) tetraaquadiglycinemagnesium(II) disulfate; [Mg(D2O)6][Mg(C2D5NO2)2(D2O)4](SO4)2} above ∼330 K in air. X-ray powder diffraction analysis reveals that the trihydrate phase is monoclinic (space group P21/n), with a unit-cell metric very similar to that of recently identified Gly·CoSO4·3H2O [Tepavitcharova et al. (2012). J. Mol. Struct. 1018, 113-121]. In order to obtain an accurate determination of all structural parameters, including the locations of H atoms, and to better understand the relationship between the pentahydrate and the trihydrate, neutron powder diffraction measurements of both (fully deuterated) phases were carried out at 10 K at the ISIS neutron spallation source, these being complemented with X-ray powder diffraction measurements and Raman spectroscopy. At 10 K, glycine magnesium sulfate pentahydrate, structurally described by the `double' formula [Gly(d5)·MgSO4·5D2O]2, is triclinic (space group P-1, Z = 1), and glycine magnesium sulfate trihydrate, which may be described by the formula Gly(d5)·MgSO4·3D2O, is monoclinic (space group P21/n, Z = 4). In the pentahydrate, there are two symmetry-inequivalent MgO6 octahedra on sites of -1 symmetry and two SO4 tetrahedra with site symmetry 1. The octahedra comprise one [tetraaquadiglcyinemagnesium](2+) ion (centred on Mg1) and one [hexaaquamagnesium](2+) ion (centred on Mg2), and the glycine zwitterion, NH3(+)CH2COO(-), adopts a monodentate coordination to Mg2. In the

  2. X-ray Absorption Spectroscopy

    SciTech Connect

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  3. Branched pore kinetic model analysis of geosmin adsorption on super-powdered activated carbon.

    PubMed

    Matsui, Yoshihiko; Ando, Naoya; Sasaki, Hiroshi; Matsushita, Taku; Ohno, Koichi

    2009-07-01

    Super-powdered activated carbon (S-PAC) is activated carbon of much finer particle size than powdered activated carbon (PAC). Geosmin is a naturally occurring taste and odor compound that impairs aesthetic quality in drinking water. Experiments on geosmin adsorption on S-PAC and PAC were conducted, and the results using adsorption kinetic models were analyzed. PAC pulverization, which produced the S-PAC, did not change geosmin adsorption capacity, and geosmin adsorption capacities did not differ between S-PAC and PAC. Geosmin adsorption kinetics, however, were much higher on S-PAC than on PAC. A solution to the branched pore kinetic model (BPKM) was developed, and experimental adsorption kinetic data were analyzed by BPKM and by a homogeneous surface diffusion model (HSDM). The HSDM describing the adsorption behavior of geosmin required different surface diffusivity values for S-PAC and PAC, which indicated a decrease in surface diffusivity apparently associated with activated carbon particle size. The BPKM, consisting of macropore diffusion followed by mass transfer from macropore to micropore, successfully described the batch adsorption kinetics on S-PAC and PAC with the same set of model parameter values, including surface diffusivity. The BPKM simulation clearly showed geosmin removal was improved as activated carbon particle size decreased. The simulation also implied that the rate-determining step in overall mass transfer shifted from intraparticle radial diffusion in macropores to local mass transfer from macropore to micropore. Sensitivity analysis showed that adsorptive removal of geosmin improved with decrease in activated carbon particle size down to 1microm, but further particle size reduction produced little improvement.

  4. Thorough removal of inorganic and organic mercury from aqueous solutions by adsorption on Lemna minor powder.

    PubMed

    Li, Shun-Xing; Zheng, Feng-Ying; Yang, Huang; Ni, Jian-Cong

    2011-02-15

    The adsorption ability of duckweed (Lemna minor) powders for removing inorganic and organic mercury (methyl and ethyl mercury) has been studied using cold vapour atomic absorption spectrometry. The optimal adsorption conditions were: (a) the pH value of the solution 7.0 for inorganic and ethyl mercury, 9.0 for methyl mercury, and (b) equilibrium adsorption time 10, 20, and 40 min for inorganic mercury, methyl mercury, and ethyl mercury, respectively. After adsorption by L. minor powder for 40 min, when the initial concentrations of inorganic and organic mercury were under 12.0 μg L(-1) and 50.0 μg L(-1), respectively, the residual concentrations of mercury could meet the criterion of drinking water (1.0 μg L(-1)) and the permitted discharge limit of wastewater (10.0 μg L(-1)) set by China and USEPA, respectively. Thorough removal of both inorganic and organic mercury from aqueous solutions was reported for the first time. The significant adsorption sites were C-O-P and phosphate groups by the surface electrostatic interactions with aqueous inorganic and organic mercury cations, and then the selective adsorption was resulted from the strong chelating interaction between amine groups and mercury on the surface of L. minor cells.

  5. X-ray chemical analyzer for field applications

    DOEpatents

    Gamba, Otto O. M.

    1977-01-01

    A self-supporting portable field multichannel X-ray chemical analyzer system comprising a lightweight, flexibly connected, remotely locatable, radioisotope-excited sensing probe utilizing a cryogenically-cooled solid state semi-conductor crystal detector for fast in situ non-destructive, qualitative and quantitative analysis of elements in solid, powder, liquid or slurried form, utilizing an X-ray energy dispersive spectrometry technique.

  6. Phase-targeted X-ray diffraction

    PubMed Central

    Hansford, G. M.

    2016-01-01

    A powder X-ray diffraction (XRD) method to enhance the signal of a specific crystalline phase within a mixture is presented for the first time. Specificity to the targeted phase relies on finding coincidences in the ratios of crystal d spacings and the ratios of elemental characteristic X-ray energies. Such coincidences can be exploited so that the two crystal planes diffract through the same scattering angle at two different X-ray energies. An energy-resolving detector placed at the appropriate scattering angle will detect a significantly enhanced signal at these energies if the target mineral or phase is present in the sample. When implemented using high scattering angles, for example 2θ > 150°, the method is tolerant to sample morphology and distance on the scale of ∼2 mm. The principle of the method is demonstrated experimentally using Pd Lα1 and Pd Lβ1 emission lines to enhance the diffraction signal of quartz. Both a pure quartz powder pellet and an unprepared mudstone rock specimen are used to test and develop the phase-targeted method. The technique is further demonstrated in the sensitive detection of retained austenite in steel samples using a combination of In Lβ1 and Ti Kβ emission lines. For both these examples it is also shown how the use of an attenuating foil, with an absorption edge close to and above the higher-energy characteristic X-ray line, can serve to isolate to some degree the coincidence signals from other fluorescence and diffraction peaks in the detected spectrum. The phase-targeted XRD technique is suitable for implementation using low-cost off-the-shelf components in a handheld or in-line instrument format. PMID:27738415

  7. Probing the orientation of electrostatically immobilized Protein G B1 by time-of-flight secondary ion spectrometry, sum frequency generation, and near-edge X-ray adsorption fine structure spectroscopy.

    PubMed

    Baio, Joe E; Weidner, Tobias; Baugh, Loren; Gamble, Lara J; Stayton, Patrick S; Castner, David G

    2012-01-31

    To fully develop techniques that provide an accurate description of protein structure at a surface, we must start with a relatively simple model system before moving to increasingly complex systems. In this study, X-ray photoelectron spectroscopy (XPS), sum frequency generation spectroscopy (SFG), near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to probe the orientation of Protein G B1 (6 kDa) immobilized onto both amine (NH(3)(+)) and carboxyl (COO(-)) functionalized gold. Previously, we have shown that we could successfully control orientation of a similar Protein G fragment via a cysteine-maleimide bond. In this investigation, to induce opposite end-on orientations, a charge distribution was created within the Protein G B1 fragment by first substituting specific negatively charged amino acids with neutral amino acids and then immobilizing the protein onto two oppositely charged self-assembled monolayer (SAM) surfaces (NH(3)(+) and COO(-)). Protein coverage, on both surfaces, was monitored by the change in the atomic % N, as determined by XPS. Spectral features within the SFG spectra, acquired for the protein adsorbed onto a NH(3)(+)-SAM surface, indicates that this electrostatic interaction does induce the protein to form an oriented monolayer on the SAM substrate. This corresponded to the polarization dependence of the spectral feature related to the NEXAFS N(1s)-to-π* transition of the β-sheet peptide bonds within the protein layer. ToF-SIMS data demonstrated a clear separation between the two samples based on the intensity differences of secondary ions stemming from amino acids located asymmetrically within Protein G B1 (methionine: 62 and 105 m/z; tyrosine: 107 and 137 m/z; leucine: 86 m/z). For a more quantitative examination of orientation, we developed a ratio comparing the sum of the intensities of secondary-ions stemming from the amino acid residues at either end

  8. X-ray beam pointer

    NASA Technical Reports Server (NTRS)

    Nelson, C. W.

    1980-01-01

    Inexpensive, readily assembled pointer aims X-ray machine for welded assembly radiographs. Plumb bob used for vertical alinement and yardstick used to visualize X-ray paths were inconvenient and inaccurate. Pointer cuts alinement time by one-half and eliminates necessity of retakes. For 3,000 weld radiographs, pointer will save 300 worker-hours and significant materials costs.

  9. X-ray based extensometry

    NASA Technical Reports Server (NTRS)

    Jordan, E. H.; Pease, D. M.

    1988-01-01

    A totally new method of extensometry using an X-ray beam was proposed. The intent of the method is to provide a non-contacting technique that is immune to problems associated with density variations in gaseous environments that plague optical methods. X-rays are virtually unrefractable even by solids. The new method utilizes X-ray induced X-ray fluorescence or X-ray induced optical fluorescence of targets that have melting temperatures of over 3000 F. Many different variations of the basic approaches are possible. In the year completed, preliminary experiments were completed which strongly suggest that the method is feasible. The X-ray induced optical fluorescence method appears to be limited to temperatures below roughly 1600 F because of the overwhelming thermal optical radiation. The X-ray induced X-ray fluorescence scheme appears feasible up to very high temperatures. In this system there will be an unknown tradeoff between frequency response, cost, and accuracy. The exact tradeoff can only be estimated. It appears that for thermomechanical tests with cycle times on the order of minutes a very reasonable system may be feasible. The intended applications involve very high temperatures in both materials testing and monitoring component testing. Gas turbine engines, rocket engines, and hypersonic vehicles (NASP) all involve measurement needs that could partially be met by the proposed technology.

  10. Physicochemical properties and adsorption of cholesterol by okra (Abelmoschus esculentus) powder.

    PubMed

    Chen, Yi; Zhang, Bing-Cheng; Sun, Yu-Han; Zhang, Jian-Guo; Sun, Han-Ju; Wei, Zhao-Jun

    2015-12-01

    Okra (Abelmoschus esculentus) is a widely used medicine and functional food. In order to clarify the effects of the particle size on its functional properties, okra pods were subjected to superfine grinding, and its properties were determined using different methods. Four particle size levels of okra powders were prepared: 380 to 250, 250 to 75, 75 to 40 and less than 40 μm. The results showed that superfine grinding technology could efficiently pulverize the particles into the submicron scale, whose distribution was close to a Gaussian distribution. With decreasing okra powder size, the specific surface area, water holding capacity (WHC), water-retention capacity (WRC), oil-binding capacity (OBC), tapped density and total flavonoids extraction were increased significantly (p < 0.05). Moreover, the adsorption of cholesterol by okra powder was improved after superfine grinding. These results suggest that okra powder can be used in food manufacturing as a functional food ingredient.

  11. Physicochemical properties and adsorption of cholesterol by okra (Abelmoschus esculentus) powder.

    PubMed

    Chen, Yi; Zhang, Bing-Cheng; Sun, Yu-Han; Zhang, Jian-Guo; Sun, Han-Ju; Wei, Zhao-Jun

    2015-12-01

    Okra (Abelmoschus esculentus) is a widely used medicine and functional food. In order to clarify the effects of the particle size on its functional properties, okra pods were subjected to superfine grinding, and its properties were determined using different methods. Four particle size levels of okra powders were prepared: 380 to 250, 250 to 75, 75 to 40 and less than 40 μm. The results showed that superfine grinding technology could efficiently pulverize the particles into the submicron scale, whose distribution was close to a Gaussian distribution. With decreasing okra powder size, the specific surface area, water holding capacity (WHC), water-retention capacity (WRC), oil-binding capacity (OBC), tapped density and total flavonoids extraction were increased significantly (p < 0.05). Moreover, the adsorption of cholesterol by okra powder was improved after superfine grinding. These results suggest that okra powder can be used in food manufacturing as a functional food ingredient. PMID:26359588

  12. Ab Initio Structure Determination of New Mixed Zirconium Hydroxide Nitrates Zr M(OH) 2(NO 3) 3 ( M=K, Rb) from X-Ray Powder Diffraction Data

    NASA Astrophysics Data System (ADS)

    Bénard-Rocherullé, P.; Louër, D.

    2000-01-01

    Two new mixed zirconium hydroxide nitrates ZrM(OH)2(NO3)3 (M=K, Rb) have been synthesized through a wet chemical process. The two crystal structures have been solved ab initio from powder diffraction data collected with conventional monochromatic X-rays. ZrK(OH)2(NO3)3 crystallizes with a monoclinic symmetry [a=16.569(3) Å, b=5.791(1) Å, c=9.813(2) Å, β=90.17(2)°, P21/n, Z=4) and ZrRb(OH)2(NO3)3 with an orthorhombic symmetry [a=10.126(3) Å, b=16.492(3) Å, c=5.855(2) Å, Pbcn, Z=4]. The heavy atoms have been located from an interpretation of Patterson functions. The coordinates of the remaining light atoms have been determined from successive three-dimensional Fourier maps. The final Rietveld refinement indicators were RF=0.042, Rp=0.077 (M=K) and RF=0.064, Rp=0.115 (M=Rb). Like the structures of α-Zr(OH)2(NO3)2·1.65H2O and β-Zr(OH)2(NO3)2·H2O, the structures of the mixed basic zirconium nitrates are built from edge-sharing ZrO8 polyhedra to form infinite neutral zigzag chains of chemical composition [Zr(OH)4/2(NO3)2]n. The main difference with respect to the hydrated phases is the nature of the cohesion in the structures based on ionic contacts involving intercalated K+ or Rb+ and NO-3 species in the mixed compounds and on a complex hydrogen-bonding network in the hydrated phases. The crystal chemistry of the zirconium hydroxide nitrates is discussed and three structure types are identified.

  13. X-Ray Tomographic Reconstruction

    SciTech Connect

    Bonnie Schmittberger

    2010-08-25

    Tomographic scans have revolutionized imaging techniques used in medical and biological research by resolving individual sample slices instead of several superimposed images that are obtained from regular x-ray scans. X-Ray fluorescence computed tomography, a more specific tomography technique, bombards the sample with synchrotron x-rays and detects the fluorescent photons emitted from the sample. However, since x-rays are attenuated as they pass through the sample, tomographic scans often produce images with erroneous low densities in areas where the x-rays have already passed through most of the sample. To correct for this and correctly reconstruct the data in order to obtain the most accurate images, a program employing iterative methods based on the inverse Radon transform was written. Applying this reconstruction method to a tomographic image recovered some of the lost densities, providing a more accurate image from which element concentrations and internal structure can be determined.

  14. Focusing X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    O'Dell, Stephen; Brissenden, Roger; Davis, William; Elsner, Ronald; Elvis, Martin; Freeman, Mark; Gaetz, Terrance; Gorenstein, Paul; Gubarev, Mikhall; Jerlus, Diab; Juda, Michael; Kolodziejczak, Jeffrey; Murray, Stephen; Petre, Robert; Podgorski, William; Ramsey, Brian; Reid, Paul; Saha, Timo; Wolk, Scott; Troller-McKinstry, Susan; Weisskopf, Martin; Wilke, Rudeger; Zhang, William

    2010-01-01

    During the half-century history of x-ray astronomy, focusing x-ray telescopes, through increased effective area and finer angular resolution, have improved sensitivity by 8 orders of magnitude. Here, we review previous and current x-ray-telescope missions. Next, we describe the planned next-generation x-ray-astronomy facility, the International X-ray Observatory (IXO). We conclude with an overview of a concept for the next next-generation facility, Generation X. Its scientific objectives will require very large areas (about 10,000 sq m) of highly-nested, lightweight grazing-incidence mirrors, with exceptional (about 0.1-arcsec) resolution. Achieving this angular resolution with lightweight mirrors will likely require on-orbit adjustment of alignment and figure.

  15. X-ray shearing interferometer

    DOEpatents

    Koch, Jeffrey A.

    2003-07-08

    An x-ray interferometer for analyzing high density plasmas and optically opaque materials includes a point-like x-ray source for providing a broadband x-ray source. The x-rays are directed through a target material and then are reflected by a high-quality ellipsoidally-bent imaging crystal to a diffraction grating disposed at 1.times. magnification. A spherically-bent imaging crystal is employed when the x-rays that are incident on the crystal surface are normal to that surface. The diffraction grating produces multiple beams which interfere with one another to produce an interference pattern which contains information about the target. A detector is disposed at the position of the image of the target produced by the interfering beams.

  16. Removal of methylene blue from aqueous solution by adsorption onto pineapple leaf powder.

    PubMed

    Weng, Chih-Huang; Lin, Yao-Tung; Tzeng, Tai-Wei

    2009-10-15

    The ability of an unconventional bio-adsorbent, pineapple leaf powder (PLP) for the adsorption of methylene blue (MB) from aqueous solution was studied. It was observed that intra-particle diffusion was involved in the adsorption process and that the kinetic data fitted well with a pseudo-second-order equation. Fitting parameters revealed that the rate of adsorption increased with decrease in dye concentration and decrease in ionic strength while the mixing speed did not have a significant effect on adsorption. The adsorption was favorable at higher pH and lower temperature, and the equilibrium data were well fitted by the Langmuir isotherm. The maximum adsorption capacity varied from 4.68 x 10(-4) to 9.28 x 10(-4)mol/g when pH increases from 3.5 to 9.5. Thermodynamic parameters suggest that the adsorption is a typical physical process, spontaneous, and exothermic in nature. The results revealed that this agricultural waste has potential to be used as an economical adsorbent for the removal of methylene blue from aqueous solution.

  17. Removal of methylene blue from aqueous solution by adsorption onto pineapple leaf powder.

    PubMed

    Weng, Chih-Huang; Lin, Yao-Tung; Tzeng, Tai-Wei

    2009-10-15

    The ability of an unconventional bio-adsorbent, pineapple leaf powder (PLP) for the adsorption of methylene blue (MB) from aqueous solution was studied. It was observed that intra-particle diffusion was involved in the adsorption process and that the kinetic data fitted well with a pseudo-second-order equation. Fitting parameters revealed that the rate of adsorption increased with decrease in dye concentration and decrease in ionic strength while the mixing speed did not have a significant effect on adsorption. The adsorption was favorable at higher pH and lower temperature, and the equilibrium data were well fitted by the Langmuir isotherm. The maximum adsorption capacity varied from 4.68 x 10(-4) to 9.28 x 10(-4)mol/g when pH increases from 3.5 to 9.5. Thermodynamic parameters suggest that the adsorption is a typical physical process, spontaneous, and exothermic in nature. The results revealed that this agricultural waste has potential to be used as an economical adsorbent for the removal of methylene blue from aqueous solution. PMID:19447547

  18. Hard X-Ray Emission of X-Ray Bursters

    NASA Technical Reports Server (NTRS)

    Kaaret, Phillip

    1997-01-01

    The main results from this investigation were serendipitous. The long observation approved for the study of the hard X-ray emission of X-ray bursters lead, instead, to one of the largest early samples of the behavior of fast quasi-periodic oscillations (QPOS) in an atoll sources. Our analysis of this data set lead to the several important discoveries including the existence of a robust correlation between QPO frequency and the flux of a soft blackbody component of the X-ray spectrum in the atoll source 4U 0614+091.

  19. The ammonium ion in a silicate under compression: infrared spectroscopy and powder X-ray diffraction of NH4AlSi3O8—buddingtonite to 30 GPa

    NASA Astrophysics Data System (ADS)

    E. Vennari, Cara; O'Bannon, Earl F.; Williams, Quentin

    2016-10-01

    The behavior of the ammoniated feldspar buddingtonite, NH4AlSi3O8, has been studied using infrared (IR) spectroscopy up to ~30 GPa and using synchrotron powder X-ray diffraction to 10 GPa at room temperature. We examine the bonding of the ammonium ion under pressure and in particular whether hydrogen bonding is enhanced by compaction, as well as probe how the ammonium ion affects the elasticity and behavior of the aluminosilicate framework at pressure. Powder diffraction data yield a bulk modulus of 49 GPa for a pressure derivative of 4, implying that the ammonium ion substitution may induce a modest softening of the feldspar lattice relative to the potassium ion. Under compression, the N-H vibrations are remarkably insensitive to pressure throughout the pressure range of these experiments. However, the vibrations of the aluminosilicate framework of buddingtonite undergo changes in their slope at ~13 GPa, implying that a change in compressional mechanism occurs near this pressure, but the vibrational modes of the ammonium molecule show little response to this change. These results show that (1) there is little, if any, enhancement of hydrogen bonding between the ammonium ion and the oxygen ions of the silica and aluminum tetrahedral framework under pressure, as manifested by the slight (and mostly positive) shifts in the N-H stretching vibrations of the ammonium ion; (2) ordering of the ammonium ion is not observed under compression, as no changes in peak width or in the general appearance of the spectra are observed under compression; and (3) structural changes induced by pressure in the aluminosilicate framework do not produce significant changes in the bonding of the ammonium ion. Hence, it appears that the ammonium ion interacts minimally with its surrounding lattice, even at high pressures: Its behavior is compatible with it being, aside from Coulombic attraction to the oxygen-dominated matrix, a largely non-interactive guest molecule within the silicate

  20. X-Ray photonics: X-rays inspire electron movies

    NASA Astrophysics Data System (ADS)

    Vrakking, Marc J. J.; Elsaesser, Thomas

    2012-10-01

    The advent of high-energy, short-pulse X-ray sources based on free-electron lasers, laser plasmas and high-harmonic generation is now making it possible to probe the dynamics of electrons within molecules.

  1. Adsorption of heavy metal from aqueous solution by dehydrated root powder of long-root Eichhornia crassipes.

    PubMed

    Li, Qiang; Chen, Bo; Lin, Peng; Zhou, Jiali; Zhan, Juhong; Shen, Qiuying; Pan, Xuejun

    2016-01-01

    The root powder of long-root Eichhornia crassipes, as a new kind of biodegradable adsorbent, has been tested for aqueous adsorption of Pb, Zn, Cu, and Cd. From FT-IR, we found that the absorption peaks of phosphorous compounds, carbonyl, and nitrogenous compounds displayed obvious changes before and after adsorption which illustrated that plant characteristics may play a role in binding with metals. Surface properties and morphology of the root powders have been characterized by means of SEM and BET. Energy spectrum analysis showed that the metals were adsorbed on root powders after adsorption. Then, optimum quantity of powder, pH values, and metal ion concentrations in single-system and multi-system were detected to discuss the characteristics and mechanisms of metal adsorption. Freundlich model and the second-order kinetics equation could well describe the adsorption of heavy metals in single-metal system. The adsorption of Pb, Zn, and Cd in the multi-metal system decreased with the concentration increased. At last, competitive adsorption of every two metals on root powder proved that Cu and Pb had suppressed the adsorption performance of Cd and Zn.

  2. Adsorption of heavy metal from aqueous solution by dehydrated root powder of long-root Eichhornia crassipes.

    PubMed

    Li, Qiang; Chen, Bo; Lin, Peng; Zhou, Jiali; Zhan, Juhong; Shen, Qiuying; Pan, Xuejun

    2016-01-01

    The root powder of long-root Eichhornia crassipes, as a new kind of biodegradable adsorbent, has been tested for aqueous adsorption of Pb, Zn, Cu, and Cd. From FT-IR, we found that the absorption peaks of phosphorous compounds, carbonyl, and nitrogenous compounds displayed obvious changes before and after adsorption which illustrated that plant characteristics may play a role in binding with metals. Surface properties and morphology of the root powders have been characterized by means of SEM and BET. Energy spectrum analysis showed that the metals were adsorbed on root powders after adsorption. Then, optimum quantity of powder, pH values, and metal ion concentrations in single-system and multi-system were detected to discuss the characteristics and mechanisms of metal adsorption. Freundlich model and the second-order kinetics equation could well describe the adsorption of heavy metals in single-metal system. The adsorption of Pb, Zn, and Cd in the multi-metal system decreased with the concentration increased. At last, competitive adsorption of every two metals on root powder proved that Cu and Pb had suppressed the adsorption performance of Cd and Zn. PMID:26605425

  3. Be/X-ray binaries

    NASA Astrophysics Data System (ADS)

    Reig, Pablo

    2011-03-01

    The interest in X/ γ-ray Astronomy has grown enormously in the last decades thanks to the ability to send X-ray space missions above the Earth’s atmosphere. There are more than half a million X-ray sources detected and over a hundred missions (past and currently operational) devoted to the study of cosmic X/ γ rays. With the improved sensibilities of the currently active missions new detections occur almost on a daily basis. Among these, neutron-star X-ray binaries form an important group because they are among the brightest extra-solar objects in the sky and are characterized by dramatic variability in brightness on timescales ranging from milliseconds to months and years. Their main source of power is the gravitational energy released by matter accreted from a companion star and falling onto the neutron star in a relatively close binary system. Neutron-star X-ray binaries divide into high-mass and low-mass systems according to whether the mass of the donor star is above ˜8 or below ˜2 M⊙, respectively. Massive X-ray binaries divide further into supergiant X-ray binaries and Be/X-ray binaries depending on the evolutionary status of the optical companion. Virtually all Be/X-ray binaries show X-ray pulsations. Therefore, these systems can be used as unique natural laboratories to investigate the properties of matter under extreme conditions of gravity and magnetic field. The purpose of this work is to review the observational properties of Be/X-ray binaries. The open questions in Be/X-ray binaries include those related to the Be star companion, that is, the so-called “Be phenomenon”, such as, timescales associated to the formation and dissipation of the equatorial disc, mass-ejection mechanisms, V/ R variability, and rotation rates; those related to the neutron star, such as, mass determination, accretion physics, and spin period evolution; but also, those that result from the interaction of the two constituents, such as, disc truncation and mass

  4. X-ray burst sources

    NASA Technical Reports Server (NTRS)

    Lewin, W. H. G.

    1986-01-01

    There are about 100 bright X-ray sources in the Galaxy that are accretion-driven systems composed of a neutron star and a low mass companion that fills its critical Roche lobe. Many of these systems generate recurring X-ray bursts that are the result of thermonuclear flashes in the neutron star's surface layers, and are accompanied by a somewhat delayed optical burst due to X-ray heating of accretion disk. The Rapid Burster discovered in 1976 exhibits an interval between bursts that is strongly correlated with the energy in the preceding burst. There is no optical identification for this object.

  5. X-Ray Imaging System

    NASA Astrophysics Data System (ADS)

    1986-01-01

    The FluoroScan Imaging System is a high resolution, low radiation device for viewing stationary or moving objects. It resulted from NASA technology developed for x-ray astronomy and Goddard application to a low intensity x-ray imaging scope. FlouroScan Imaging Systems, Inc, (formerly HealthMate, Inc.), a NASA licensee, further refined the FluoroScan System. It is used for examining fractures, placement of catheters, and in veterinary medicine. Its major components include an x-ray generator, scintillator, visible light image intensifier and video display. It is small, light and maneuverable.

  6. X-ray imaging with photostimulable phosphors

    NASA Astrophysics Data System (ADS)

    von Seggern, Heinz

    1992-11-01

    Image plates based on photostimulable X-ray storage phosphors establish a promissing alternative to conventionally utilized two-dimensional X-ray detectors. These image plates consist of a layer of powdered X-ray storage phosphor, usually the alkaline-earth halide BaFBr:Eu 2+, mixed with an organic binder and mounted on a polymeric film. Upon absorption of ionizing radiation, electrons and holes are produced efficiently. Both species are trapped in the immediate surrounding of their creation thereby forming a latent image. The readout of this image occurs by photostimulation whereby the trapped electrons are liberated and recombine radiatively with the trapped holes under emission of Eu 2+ light. In the present paper the principle of the imaging system is introduced followed by a brief review of the underlying physics explaining the nature of the involved traps and the mechanism of photostimulation. Advantages and disadvantages of image plate detectors and their physical nature are discussed and possible improvements suggested. Present and future fields of application are presented.

  7. X-ray microtomographic scanners

    SciTech Connect

    Syryamkin, V. I. Klestov, S. A.

    2015-11-17

    The article studies the operating procedures of an X-ray microtomographic scanner and the module of reconstruction and analysis 3D-image of a test sample in particular. An algorithm for 3D-image reconstruction based on image shadow projections and mathematical methods of the processing are described. Chapter 1 describes the basic principles of X-ray tomography and general procedures of the device developed. Chapters 2 and 3 are devoted to the problem of resources saving by the system during the X-ray tomography procedure, which is achieved by preprocessing of the initial shadow projections. Preprocessing includes background noise removing from the images, which reduces the amount of shadow projections in general and increases the efficiency of the group shadow projections compression. In conclusion, the main applications of X-ray tomography are presented.

  8. Imaging X-ray spectrometer

    NASA Technical Reports Server (NTRS)

    Grant, P. A.; Jackson, J. W., Jr.; Alcorn, G. E.; Marshall, F. E. (Inventor)

    1984-01-01

    An X-ray spectrometer for providing imaging and energy resolution of an X-ray source is described. This spectrometer is comprised of a thick silicon wafer having an embedded matrix or grid of aluminum completely through the wafer fabricated, for example, by thermal migration. The aluminum matrix defines the walls of a rectangular array of silicon X-ray detector cells or pixels. A thermally diffused aluminum electrode is also formed centrally through each of the silicon cells with biasing means being connected to the aluminum cell walls and causes lateral charge carrier depletion between the cell walls so that incident X-ray energy causes a photoelectric reaction within the silicon producing collectible charge carriers in the form of electrons which are collected and used for imaging.

  9. X-ray fiducial foils

    SciTech Connect

    Alford, C.; Serduke, F.; Makowiecki, D.; Jankowski, A.; Wall, M.

    1991-03-13

    An x-ray spectrum from a laser fusion experiment was passed through an Al, Si, Y multilayer foil. The position of the absorption edges of the Al, Si, and Y was used to calibrate the x-ray energy spectrum recorded on photographic film. The foil consisted of 4000 {angstrom} of Al, 6000 {angstrom} of Si and 4000 {angstrom} of Y sputter deposited on a 1.5 {mu}m thick Mylar{reg sign} film. It was necessary to layer the structure in order to achieve the required mechanical strength and dimensional stability. The results include analysis of the x-ray energy spectrum and microstructural characterization of the foil using x-ray diffraction and transmission electron microscopy.

  10. Bone X-Ray (Radiography)

    MedlinePlus

    ... bone x-ray is used to: diagnose fractured bones or joint dislocation. demonstrate proper alignment and stabilization of bony fragments following treatment of a fracture. guide orthopedic surgery, ...

  11. X-Ray Imaging System

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Model 60007A InnerView Real-time X-ray Imaging System, produced by National Imaging Systems, a division of FlouroScan Imaging Systems, Inc. (formerly HealthMate, Inc.), Northbrook, IL, is a third generation spinoff from x-ray astronomy technology. Goddard Space Flight Center developed the original technology into the Lixiscope, a small, portable, minimal radiation x-ray instrument that could be used at the scene of an accident. FlouroScan Imaging Systems, Inc., adapted this technology to develop the FlouroScan, a low-intensity, x-ray system that could be used without the lead aprons, film badges and lead-lined walls that conventional systems require. The InnerView is a spinoff of non-destructive testing and product inspection.

  12. Miniature x-ray source

    DOEpatents

    Trebes, James E.; Bell, Perry M.; Robinson, Ronald B.

    2000-01-01

    A miniature x-ray source utilizing a hot filament cathode. The source has a millimeter scale size and is capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature source consists of a compact vacuum tube assembly containing the hot filament cathode, an anode, a high voltage feedthru for delivering high voltage to the cathode, a getter for maintaining high vacuum, a connector for initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is fabricated from highly x-ray transparent materials, such as sapphire, diamond, or boron nitride.

  13. Abdomen X-Ray (Radiography)

    MedlinePlus

    ... have very controlled x-ray beams and dose control methods to minimize stray (scatter) radiation. This ensures that those parts of a patient's body not being imaged receive minimal radiation exposure. top ...

  14. X-Ray Exam: Finger

    MedlinePlus

    ... KidsHealth in the Classroom What Other Parents Are Reading Upsetting News Reports? What to Say Vaccines: Which ... Results A radiologist, a doctor specially trained in reading and interpreting X-ray images, will look at ...

  15. X-Ray Exam: Hip

    MedlinePlus

    ... KidsHealth in the Classroom What Other Parents Are Reading Upsetting News Reports? What to Say Vaccines: Which ... For older kids, be sure to explain the importance of keeping still while the X-ray is ...

  16. X-Ray Exam: Foot

    MedlinePlus

    ... KidsHealth in the Classroom What Other Parents Are Reading Upsetting News Reports? What to Say Vaccines: Which ... For older kids, be sure to explain the importance of staying still while the X-ray is ...

  17. X-Ray Exam: Ankle

    MedlinePlus

    ... KidsHealth in the Classroom What Other Parents Are Reading Upsetting News Reports? What to Say Vaccines: Which ... For older kids, be sure to explain the importance of staying still while the X-ray is ...

  18. X-Ray Exam: Pelvis

    MedlinePlus

    ... KidsHealth in the Classroom What Other Parents Are Reading Upsetting News Reports? What to Say Vaccines: Which ... For older kids, be sure to explain the importance of keeping still while the X-ray is ...

  19. X-Ray Exam: Forearm

    MedlinePlus

    ... KidsHealth in the Classroom What Other Parents Are Reading Upsetting News Reports? What to Say Vaccines: Which ... For older kids, be sure to explain the importance of staying still while the X-ray is ...

  20. X-Ray Exam: Wrist

    MedlinePlus

    ... KidsHealth in the Classroom What Other Parents Are Reading Upsetting News Reports? What to Say Vaccines: Which ... For older kids, be sure to explain the importance of staying still while the X-ray is ...

  1. Electromechanical x-ray generator

    DOEpatents

    Watson, Scott A; Platts, David; Sorensen, Eric B

    2016-05-03

    An electro-mechanical x-ray generator configured to obtain high-energy operation with favorable energy-weight scaling. The electro-mechanical x-ray generator may include a pair of capacitor plates. The capacitor plates may be charged to a predefined voltage and may be separated to generate higher voltages on the order of hundreds of kV in the AK gap. The high voltage may be generated in a vacuum tube.

  2. X-Rays, Pregnancy and You

    MedlinePlus

    ... and Procedures Medical Imaging Medical X-ray Imaging X-Rays, Pregnancy and You Share Tweet Linkedin Pin it ... the decision with your doctor. What Kind of X-Rays Can Affect the Unborn Child? During most x- ...

  3. Why Do I Need X-Rays?

    MedlinePlus

    ... to your desktop! more... Why Do I Need X-Rays? Article Chapters Why Do I Need X-Rays? ... of tooth decay. Updated: January 2012 Related Articles: X-Rays The Academy of General Dentistry (AGD) Sets the ...

  4. Nanometer x-ray lithography

    NASA Astrophysics Data System (ADS)

    Hartley, Frank T.; Khan Malek, Chantal G.

    1999-10-01

    New developments for x-ray nanomachining include pattern transfer onto non-planar surfaces coated with electrodeposited resists using synchrotron radiation x-rays through extremely high-resolution mask made by chemically assisted focused ion beam lithography. Standard UV photolithographic processes cannot maintain sub-micron definitions over large variation in feature topography. The ability of x-ray printing to pattern thin or thick layers of photoresist with high resolution on non-planar surfaces of large and complex topographies with limited diffraction and scattering effects and no substrate reflection is known and can be exploited for patterning microsystems with non-planar 3D geometries as well as multisided and multilayered substrates. Thin conformal coatings of electro-deposited positive and negative tone photoresist have been shown to be x-ray sensitive and accommodate sub-micro pattern transfer over surface of extreme topographical variations. Chemically assisted focused ion beam selective anisotropic erosion was used to fabricate x-ray masks directly. Masks with feature sizes less than 20 nm through 7 microns of gold were made on bulk silicon substrates and x-ray mask membranes. The technique is also applicable to other high density materials. Such masks enable the primary and secondary patterning and/or 3D machining of Nano-Electro-Mechanical Systems over large depths or complex relief and the patterning of large surface areas with sub-optically dimensioned features.

  5. Tokamak x ray diagnostic instrumentation

    SciTech Connect

    Hill, K.W.; Beiersdorfer, P.; Bitter, M.; Fredrickson, E.; Von Goeler, S.; Hsuan, H.; Johnson, L.C.; Liew, S.L.; McGuire, K.; Pare, V.

    1987-01-01

    Three classes of x-ray diagnostic instruments enable measurement of a variety of tokamak physics parameters from different features of the x-ray emission spectrum. (1) The soft x-ray (1 to 50 keV) pulse-height-analysis (PHA) diagnostic measures impurity concentrations from characteristic line intensities and the continuum enhancement, and measures the electron temperature from the continuum slope. (2) The Bragg x-ray crystal spectrometer (XCS) measures the ion temperature and neutral-beam-induced toroidal rotation velocity from the Doppler broadening and wavelength shift, respectively, of spectral lines of medium-Z impurity ions. Impurity charge state distributions, precise wavelengths, and inner-shell excitation and recombination rates can also be studied. X rays are diffracted and focused by a bent crystal onto a position-sensitive detector. The spectral resolving power E/..delta..E is greater than 10/sup 4/ and time resolution is 10 ms. (3) The x-ray imaging system (XIS) measures the spatial structure of rapid fluctuations (0.1 to 100 kHZ) providing information on MHD phenomena, impurity transport rates, toroidal rotation velocity, plasma position, and the electron temperature profile. It uses an array of silicon surface-barrier diodes which view different chords of the plasma through a common slot aperture and operate in current (as opposed to counting) mode. The effectiveness of shields to protect detectors from fusion-neutron radiation effects has been studied both theoretically and experimentally.

  6. Solid state 13C-NMR, infrared, X-ray powder diffraction and differential thermal studies of the homologous series of some mono-valent metal (Li, Na, K, Ag) n-alkanoates: A comparative study

    NASA Astrophysics Data System (ADS)

    Nelson, Peter N.; Ellis, Henry A.; White, Nicole A. S.

    2015-06-01

    A comparative study of the molecular packing, lattice structures and phase behaviors of the homologous series of some mono-valent metal carboxylates (Li, Na, K and Ag) is carried out via solid state FT-infrared and 13C-NMR spectroscopes, X-rays powder diffraction, density measurements, differential scanning calorimetry, polarizing light microscopy and variable temperature infrared spectroscopy. It is proposed that, for lithium, sodium and potassium carboxylates, metal-carboxyl coordination is via asymmetric chelating bidentate bonding with extensive intermolecular interactions to form tetrahedral metal centers, irrespective of chain length. However, for silver n-alkanoates, carboxyl moieties are bound to silver ions via syn-syn type bridging bidentate coordination to form dimeric units held together by extensive head group inter-molecular interactions. Furthermore, the fully extended hydrocarbon chains which are crystallized in the all-trans conformation are tilted at ca. 30°, 27°, 15° and 31° with respect to a normal to the metal plane, for lithium, sodium, silver and potassium carboxylates, respectively. All compounds are packed as lamellar bilayer structures, however, lithium compounds are crystallized in a triclinic crystal system whilst silver, sodium and potassium n-alkanoates are all monoclinic with possible P1 bravais lattice. Odd-even alternation observed in various physical features is associated with different inter-planar spacing between closely packed layers in the bilayer which are not in the same plane; a phenomenon controlled by lattice packing symmetry requirements. All compounds, except silver carboxylates, show partially reversibly first order pre-melting transitions; the number of which increases with increasing chain length. These transitions are associated, for the most part, with lamellar collapse followed by increased gauche-trans isomerism in the methylene group assembly, irrespective of chain length. It is proposed that the absence of

  7. Solid state ¹³C-NMR, infrared, X-ray powder diffraction and differential thermal studies of the homologous series of some mono-valent metal (Li, Na, K, Ag) n-alkanoates: a comparative study.

    PubMed

    Nelson, Peter N; Ellis, Henry A; White, Nicole A S

    2015-06-15

    A comparative study of the molecular packing, lattice structures and phase behaviors of the homologous series of some mono-valent metal carboxylates (Li, Na, K and Ag) is carried out via solid state FT-infrared and (13)C-NMR spectroscopes, X-rays powder diffraction, density measurements, differential scanning calorimetry, polarizing light microscopy and variable temperature infrared spectroscopy. It is proposed that, for lithium, sodium and potassium carboxylates, metal-carboxyl coordination is via asymmetric chelating bidentate bonding with extensive intermolecular interactions to form tetrahedral metal centers, irrespective of chain length. However, for silver n-alkanoates, carboxyl moieties are bound to silver ions via syn-syn type bridging bidentate coordination to form dimeric units held together by extensive head group inter-molecular interactions. Furthermore, the fully extended hydrocarbon chains which are crystallized in the all-trans conformation are tilted at ca. 30°, 27°, 15° and 31° with respect to a normal to the metal plane, for lithium, sodium, silver and potassium carboxylates, respectively. All compounds are packed as lamellar bilayer structures, however, lithium compounds are crystallized in a triclinic crystal system whilst silver, sodium and potassium n-alkanoates are all monoclinic with possible P1 bravais lattice. Odd-even alternation observed in various physical features is associated with different inter-planar spacing between closely packed layers in the bilayer which are not in the same plane; a phenomenon controlled by lattice packing symmetry requirements. All compounds, except silver carboxylates, show partially reversibly first order pre-melting transitions; the number of which increases with increasing chain length. These transitions are associated, for the most part, with lamellar collapse followed by increased gauche-trans isomerism in the methylene group assembly, irrespective of chain length. It is proposed that the absence

  8. Structural characterization of iron oxide/hydroxide nanoparticles in nine different parenteral drugs for the treatment of iron deficiency anaemia by electron diffraction (ED) and X-ray powder diffraction (XRPD).

    PubMed

    Fütterer, S; Andrusenko, I; Kolb, U; Hofmeister, W; Langguth, P

    2013-12-01

    Drug products containing iron oxide and hydroxide nanoparticles (INPs) are important for the treatment of iron deficiency anaemia. Pharmaceuticals prepared by the complexation of different kinds of INPs and carbohydrates have different physicochemical and biopharmaceutic characteristics. The increasing number of parenteral non-biological complex drugs (NBCD) containing iron requires physicochemical methods for characterization and enabling of cross comparisons. In this context the structure and the level of crystallinity of the iron phases may be connected to the in vitro and in vivo dissolution rates, which etiologically determine the therapeutic and toxic effects. X-ray powder diffraction (XRPD) and electron diffraction (ED) methods were used in order to investigate the nine different parenteral iron formulations Ferumoxytol (Feraheme(®)), sodium ferric gluconate sucrose (Ferrlecit(®)), iron sucrose (Venofer(®)), low molecular weight iron dextran (CosmoFer(®)), low molecular weight iron dextran (Infed(®)), high molecular weight iron dextran (Ironate(®)), high molecular weight iron dextran (Dexferrum(®)), iron carboxymaltose (Ferinject(®)) and iron isomaltoside 1000 (Monofer(®)). The iron phase in CosmoFer(®), Ferinject(®), Monofer(®), Infed(®), Ironate(®) and Dexferrum(®) was identified as Akaganéite/Akaganéite-like (β-FeOOH), with low amounts of chloride. By combining results of both methods the iron oxide in Feraheme(®) was identified as Magnetite (Fe3O4) with spinel-like structure. Ferrlecit(®) and Venofer(®) were difficult to analyze due to the low degree of crystallinity, but the iron phase seems to fit Lepidocrocite/Lepidocrocite-like (γ-FeOOH) or an amorphous kind of structure. The structural information on the type of iron oxide or hydroxide together with the particle size allows predicting the stability of the different complexes including their labile iron content. The combination of ED and XRPD methods is a very helpful approach

  9. Center for X-Ray Optics, 1992

    SciTech Connect

    Not Available

    1993-08-01

    This report discusses the following topics: Center for X-Ray Optics; Soft X-Ray Imaging wit Zone Plate Lenses; Biological X-Ray microscopy; Extreme Ultraviolet Lithography for Nanoelectronic Pattern Transfer; Multilayer Reflective Optics; EUV/Soft X-ray Reflectometer; Photoemission Microscopy with Reflective Optics; Spectroscopy with Soft X-Rays; Hard X-Ray Microprobe; Coronary Angiography; and Atomic Scattering Factors.

  10. X-ray spectra of galactic X-ray sources

    NASA Technical Reports Server (NTRS)

    Holt, S. S.

    1980-01-01

    The spectroscopic properties of the various classes of Galactic X-ray sources are discussed, with particular emphasis on binary sources containing an accreting compact object, where post-emission scattering in an accretion disk often prevents the initially produced X-radiation from being observed directly. Theoretical interpretations and X-ray observations are considered for the cataclysmic variables, binary systems with a white dwarf as the compact object and which suffer relatively less from Thomson scattering, and the similar phenomenological spectral characteristics of the bulge sources, including soft transients, bursters and steady X-ray sources with thermal spectra, thought to represent an accreting neutron star, are pointed out. The spectral characteristics of X-ray pulsars in accreting binary systems (rather than the Crab pulsar, which is losing rotational kinetic energy with time) are then presented and interpreted in terms of accretion in the polar regions, and mechanisms for the newly discovered X-ray emission from late-type RS CVn stars are considered.

  11. Isotope microscopy visualization of the adsorption profile of 2-methylisoborneol and geosmin in powdered activated carbon.

    PubMed

    Matsui, Yoshihiko; Sakamoto, Asuka; Nakao, Soichi; Taniguchi, Takuma; Matsushita, Taku; Shirasaki, Nobutaka; Sakamoto, Naoya; Yurimoto, Hisayoshi

    2014-09-16

    Decreasing the particle size of powdered activated carbon may enhance its equilibrium adsorption capacity for small molecules and micropollutants, such as 2-methylisoborneol (MIB) and geosmin, as well as for macromolecules and natural organic matter. Shell adsorption, in which adsorbates do not completely penetrate the adsorbent but instead preferentially adsorb near the outer surface of the adsorbent, may explain this enhancement in equilibrium adsorption capacity. Here, we used isotope microscopy and deuterium-doped MIB and geosmin to directly visualize the solid-phase adsorbate concentration profiles of MIB and geosmin in carbon particles. The deuterium/hydrogen ratio, which we used as an index of the solid-phase concentration of MIB and geosmin, was higher in the shell region than in the inner region of carbon particles. Solid-phase concentrations of MIB and geosmin obtained from the deuterium/hydrogen ratio roughly agreed with those predicted by shell adsorption model analyses of isotherm data. The direct visualization of the localization of micropollutant adsorbates in activated carbon particles provided direct evidence of shell adsorption. PMID:25162630

  12. Isotope microscopy visualization of the adsorption profile of 2-methylisoborneol and geosmin in powdered activated carbon.

    PubMed

    Matsui, Yoshihiko; Sakamoto, Asuka; Nakao, Soichi; Taniguchi, Takuma; Matsushita, Taku; Shirasaki, Nobutaka; Sakamoto, Naoya; Yurimoto, Hisayoshi

    2014-09-16

    Decreasing the particle size of powdered activated carbon may enhance its equilibrium adsorption capacity for small molecules and micropollutants, such as 2-methylisoborneol (MIB) and geosmin, as well as for macromolecules and natural organic matter. Shell adsorption, in which adsorbates do not completely penetrate the adsorbent but instead preferentially adsorb near the outer surface of the adsorbent, may explain this enhancement in equilibrium adsorption capacity. Here, we used isotope microscopy and deuterium-doped MIB and geosmin to directly visualize the solid-phase adsorbate concentration profiles of MIB and geosmin in carbon particles. The deuterium/hydrogen ratio, which we used as an index of the solid-phase concentration of MIB and geosmin, was higher in the shell region than in the inner region of carbon particles. Solid-phase concentrations of MIB and geosmin obtained from the deuterium/hydrogen ratio roughly agreed with those predicted by shell adsorption model analyses of isotherm data. The direct visualization of the localization of micropollutant adsorbates in activated carbon particles provided direct evidence of shell adsorption.

  13. [Effects of pH and coexisting cations on ammonia adsorption from aqueous solution by strawberry stem powder].

    PubMed

    Liu, Hai-wei; Liu, Yun; Wang, Hai-yun; Dong, Yuan-hua

    2010-08-01

    Batch equilibrium experiments were carried out to study ammonia adsorptions from aqueous solution by strawberry (Fragaia ananassa Duchesne) stem powder. The effects of pH, coexisting cations, initial ammonia concentration and temperature were investigated as well. The results showed that the equilibrium data fitted well to the Langmuir model and Freundlich model, and the maximum adsorption capacities were 3.05, 4.24 and 4.79 mg x g(-1) at 15, 25 and 35 degrees C respectively. The increase of temperature was favorable to ammonia adsorption. The optimal pH of ammonia adsorption was in the range of 4-8. The NH4+ content decreased at higher pH and the negative charges decreased at lower pH, resulting in the decrease of ammonia adsorption at both higher and lower pH. The pH changes after adsorption buffered both effects. K+, Na+, Ca2+ and Mg2+ had no effect on ammonia adsorption by strawberry stem, but Zn2+ and Al3+ decreased the adsorption for their hydrolyzation. The ammonia adsorption by strawberry stem powder could be applied in a large pH range and could not be affected by usual metal cations in wastewater, therefore the strawberry stem powder not only could be a suitable ammonia adsorbent, but also had advantages comparing with most mineral materials.

  14. Ultrafast X-ray Sources

    SciTech Connect

    George Neil

    2010-04-19

    Since before the scattering of X-rays off of DNA led to the first understanding of the double helix structure, sources of X-rays have been an essential tool for scientists examining the structure and interactions of matter. The resolution of a microscope is proportional to the wavelength of light so x-rays can see much finer structures than visible light, down to single atoms. In addition, the energy of X-rays is resonant with the core atomic levels of atoms so with appropriate wavelengths the placement of specific atoms in a large molecule can be determined. Over 10,000 scientists use synchrotron sources, storage rings of high energy electrons, each year worldwide. As an example of such use, virtually every picture of a protein or drug molecule that one sees in the scientific press is a reconstruction based on X-ray scattering of synchrotron light from the crystallized form of that molecule. Unfortunately those pictures are static and proteins work through configuration (shape) changes in response to energy transfer. To understand how biological systems work requires following the energy flow to these molecules and tracking how shape changes drive their interaction with other molecules. We'd like to be able to freeze the action of these molecules at various steps along the way with an X-ray strobe light. How fast does it have to be? To actually get a picture of a molecule in a fixed configuration requires X-ray pulses as short as 30 femtoseconds (1/30 of a millionth of a millionth of a second). To capture the energy flow through changes in electronic levels requires a faster strobe, less than 1 femtosecond! And to acquire such information in smaller samples with higher accuracy demands brighter and brighter X-rays. Unfortunately modern synchrotrons (dubbed 3rd Generation Light Sources) cannot deliver such short bright pulses of X-rays. An entirely new approach is required, linear-accelerator (linac-)-based light sources termed 4th or Next Generation Light Sources

  15. X-ray Echo Spectroscopy.

    PubMed

    Shvyd'ko, Yuri

    2016-02-26

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >10^{8}) with broadband ≃5-13  meV dispersing systems are introduced featuring more than 10^{3} signal enhancement. The technique is general, applicable in different photon frequency domains. PMID:26967404

  16. X-rays surgical revolution.

    PubMed

    Toledo-Pereyra, Luis H

    2009-01-01

    Wilhelm Roentgen (1845-1923) created a surgical revolution with the discovery of the X-rays in late 1895 and the subsequent introduction of this technique for the management of surgical patients. No other physician or scientist had ever imagined such a powerful and worthwhile discovery. Other scientists paved the way for Roentgen to approach the use of these new X-rays for medical purposes. In this way, initially, and prior to Roentgen, Thompson, Hertz, and Lenard applied themselves to the early developments of this technology. They made good advances but never reached the clearly defined understanding brought about by Roentgen. The use of a Crookes tube, a barium platinocyanide screen, with fluorescent light and the generation of energy to propagate the cathode rays were the necessary elements for the conception of an X-ray picture. On November 8, 1895, Roentgen began his experiments on X-ray technology when he found that some kind of rays were being produced by the glass of the tube opposite to the cathode. The development of a photograph successfully completed this early imaging process. After six intense weeks of research, on December 22, he obtained a photograph of the hand of his wife, the first X-ray ever made. This would be a major contribution to the world of medicine and surgery.

  17. X-ray Echo Spectroscopy.

    PubMed

    Shvyd'ko, Yuri

    2016-02-26

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >10^{8}) with broadband ≃5-13  meV dispersing systems are introduced featuring more than 10^{3} signal enhancement. The technique is general, applicable in different photon frequency domains.

  18. Clocking Femtosecond X-Rays

    SciTech Connect

    Cavalieri, A L; Fritz, D M; Lee, S H; Bucksbaum, P H; Reis, D A; Mills, D M; Pahl, R; Rudati, J; Fuoss, P H; Stephenson, G B; Lowney, D P; MacPhee, A G; Weinstein, D; Falcone, R W; Als-Nielsen, J; Blome, C; Ischebeck, R; Schlarb, H; Tschentscher, T; Schneider, J; Sokolowski-Tinten, K; Chapman, H N; Lee, R W; Hansen, T N; Synnergren, O; Larsson, J; Techert, S; Sheppard, J; Wark, J S; Bergh, M; Calleman, C; Huldt, G; der Spoel, D v; Timneanu, N; Hajdu, J; Bong, E; Emma, P; Krejcik, P; Arthur, J; Brennan, S; Gaffney, K J; Lindenberg, A M; Hastings, J B

    2004-10-08

    The Sub-Picosecond Pulse Source (SPPS) at the Stanford Linear Accelerator Center (SLAC) produces the brightest ultrafast x-ray pulses in the world, and is the first to employ compressed femtosecond electron bunches for the x-ray source. Both SPPS and future X-ray Free Electron Lasers (XFEL's) will use precise measurements of individual electron bunches to time the arrival of x-ray pulses for time-resolved experiments. At SPPS we use electro-optic sampling (EOS) to perform these measurements. Here we present the first results using this method. An ultrafast laser pulse (135 fs) passes through an electro-optic crystal adjacent to the electron beam. The refractive index of the crystal is distorted by the strong electromagnetic fields of the ultra-relativistic electrons, and this transient birefringence is imprinted on the laser polarization. A polarizer decodes this signal, producing a time-dependent image of the compressed electron bunch. Our measurements yield the relative timing between an ultrafast optical laser and an ultrafast x-ray pulse to within 60 fs, making it possible to use the SPPS to observe atomic-scale ultrafast dynamics initiated by laser-matter interaction.

  19. In-situ mechanical testing during X-ray diffraction

    SciTech Connect

    Van Swygenhoven, Helena Van Petegem, Steven

    2013-04-15

    Deforming metals during recording X-ray diffraction patterns is a useful tool to get a deeper understanding of the coupling between microstructure and mechanical behaviour. With the advances in flux, detector speed and focussing techniques at synchrotron facilities, in-situ mechanical testing is now possible during powder diffraction and Laue diffraction. The basic principle is explained together with illustrative examples.

  20. X-ray tensor tomography

    NASA Astrophysics Data System (ADS)

    Malecki, A.; Potdevin, G.; Biernath, T.; Eggl, E.; Willer, K.; Lasser, T.; Maisenbacher, J.; Gibmeier, J.; Wanner, A.; Pfeiffer, F.

    2014-02-01

    Here we introduce a new concept for x-ray computed tomography that yields information about the local micro-morphology and its orientation in each voxel of the reconstructed 3D tomogram. Contrary to conventional x-ray CT, which only reconstructs a single scalar value for each point in the 3D image, our approach provides a full scattering tensor with multiple independent structural parameters in each volume element. In the application example shown in this study, we highlight that our method can visualize sub-pixel fiber orientations in a carbon composite sample, hence demonstrating its value for non-destructive testing applications. Moreover, as the method is based on the use of a conventional x-ray tube, we believe that it will also have a great impact in the wider range of material science investigations and in future medical diagnostics. The authors declare no competing financial interests.

  1. X-ray Crystallography Facility

    NASA Technical Reports Server (NTRS)

    1999-01-01

    University of Alabama engineer Stacey Giles briefs NASA astronaut Dr. Bornie Dunbar about the design and capabilities of the X-ray Crystallography Facility under development at the Center for Macromolecular Crystallography of the University of Alabama at Birmingham, AL, April 21, 1999. The X-ray Crystallography Facility is designed to speed the collection of protein structure information from crystals grown aboard the International Space Station. By measuring and mapping the protein crystal structure in space, researchers will avoid exposing the delicate crystals to the rigors of space travel and make important research data available to scientists much faster. The X-ray Crystallography facility is being designed and developed by the Center for Macromolecular Crystallography of the University of Alabama at Birmingham, a NASA Commercial Space Center.

  2. X-ray Crystallography Facility

    NASA Technical Reports Server (NTRS)

    1999-01-01

    University of Alabama engineer Lance Weiss briefs NASA astronaut Dr. Bornie Dunbar about the design and capabilities of the X-ray Crystallography Facility under development at the Center for Macromolecular Crystallography of the University of Alabama at Birmingham, AL, April 21, 1999. The X-ray Crystallography Facility is designed to speed the collection of protein structure information from crystals grown aboard the International Space Station. By measuring and mapping the protein crystal structure in space, researchers will avoid exposing the delicate crystals to the rigors of space travel and make important research data available to scientists much faster. The X-ray Crystallography facility is being designed and developed by the Center for Macromolecular Crystallography of the University of Alabama at Birmingham, a NASA Commercial Space Center.

  3. X-ray imaging: Perovskites target X-ray detection

    NASA Astrophysics Data System (ADS)

    Heiss, Wolfgang; Brabec, Christoph

    2016-05-01

    Single crystals of perovskites are currently of interest to help fathom fundamental physical parameters limiting the performance of perovskite-based polycrystalline solar cells. Now, such perovskites offer a technology platform for optoelectronic devices, such as cheap and sensitive X-ray detectors.

  4. Portable X-Ray Device

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Portable x-ray instrument developed by NASA now being produced commercially as an industrial tool may soon find further utility as a medical system. The instrument is Lixiscope - Low Intensity X-Ray Imaging Scope -- a self-contained, battery-powered fluoroscope that produces an instant image through use of a small amount of radioactive isotope. Originally developed by Goddard Space Flight Center, Lixiscope is now being produced by Lixi, Inc. which has an exclusive NASA license for one version of the device.

  5. Cosmic X-ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, D.; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1986-01-01

    The analysis of the beryllium-filtered data from Flight 17.020 was completed. The data base provided by the Wisconsin diffuse X-ray sky survey is being analyzed by correlating the B and C band emission with individual velocity components of neutral hydrogen. Work on a solid state detector to be used in high resolution spectroscopy of diffuse or extend X-ray sources is continuing. A series of 21 cm observations was completed. A paper on the effects of process parameter variation on the reflectivity of sputter-deposited tungsten-carvon multilayers was published.

  6. Adsorption of malachite green on groundnut shell waste based powdered activated carbon

    SciTech Connect

    Malik, R.; Ramteke, D.S. Wate, S.R.

    2007-07-01

    In the present technologically fast changing situation related to waste management practices, it is desirable that disposal of plant waste should be done in a scientific manner by keeping in view economic and pollution considerations. This is only possible when the plant waste has the potential to be used as raw material for some useful product. In the present study, groundnut shell, an agricultural waste, was used for the preparation of an adsorbent by chemical activation using ZnCl{sub 2} under optimized conditions and its comparative characterisation was conducted with commercially available powdered activated carbon (CPAC) for its physical, chemical and adsorption properties. The groundnut shell based powdered activated carbon (GSPAC) has a higher surface area, iodine and methylene blue number compared to CPAC. Both of the carbons were used for the removal of malachite green dye from aqueous solution and the effect of various operating variables, viz. adsorbent dose (0.1-1 g l{sup -1}), contact time (5-120 min) and adsorbate concentrations (100-200 mg l{sup -1}) on the removal of dye, has been studied. The experimental results indicate that at a dose of 0.5 g l{sup -1} and initial concentration of 100 mg l{sup -1}, GSPAC showed 94.5% removal of the dye in 30 min equilibrium time, while CPAC removed 96% of the dye in 15 min. The experimental isotherm data were analyzed using the linearized forms of Freundlich, Langmuir and BET equations to determine maximum adsorptive capacities. The equilibrium data fit well to the Freundlich isotherm, although the BET isotherm also showed higher correlation for both of the carbons. The results of comparative adsorption capacity of both carbons indicate that groundnut shell can be used as a low-cost alternative to commercial powdered activated carbon in aqueous solution for dye removal.

  7. Adsorption of malachite green on groundnut shell waste based powdered activated carbon.

    PubMed

    Malik, R; Ramteke, D S; Wate, S R

    2007-01-01

    In the present technologically fast changing situation related to waste management practices, it is desirable that disposal of plant waste should be done in a scientific manner by keeping in view economic and pollution considerations. This is only possible when the plant waste has the potential to be used as raw material for some useful product. In the present study, groundnut shell, an agricultural waste, was used for the preparation of an adsorbent by chemical activation using ZnCl2 under optimized conditions and its comparative characterisation was conducted with commercially available powdered activated carbon (CPAC) for its physical, chemical and adsorption properties. The groundnut shell based powdered activated carbon (GSPAC) has a higher surface area, iodine and methylene blue number compared to CPAC. Both of the carbons were used for the removal of malachite green dye from aqueous solution and the effect of various operating variables, viz. adsorbent dose (0.1-1 g l(-1)), contact time (5-120 min) and adsorbate concentrations (100-200 mg l(-1)) on the removal of dye, has been studied. The experimental results indicate that at a dose of 0.5 g l(-1) and initial concentration of 100 mg l(-1), GSPAC showed 94.5% removal of the dye in 30 min equilibrium time, while CPAC removed 96% of the dye in 15 min. The experimental isotherm data were analyzed using the linearized forms of Freundlich, Langmuir and BET equations to determine maximum adsorptive capacities. The equilibrium data fit well to the Freundlich isotherm, although the BET isotherm also showed higher correlation for both of the carbons. The results of comparative adsorption capacity of both carbons indicate that groundnut shell can be used as a low-cost alternative to commercial powdered activated carbon in aqueous solution for dye removal.

  8. Adsorptive Cathodic Stripping Voltammetric Determination of Cefoperazone in Bulk Powder, Pharmaceutical Dosage Forms, and Human Urine

    PubMed Central

    Hoang, Vu Dang; Huyen, Dao Thi; Phuc, Phan Hong

    2013-01-01

    The electroreduction behaviour and determination of cefoperazone using a hanging mercury drop electrode were investigated. Cyclic voltammograms of cefoperazone recorded in universal Britton-Robinson buffers pH 3–6 exhibited a single irreversible cathodic peak. The process was adsorption-controlled. Britton-Robinson buffer 0.04 M pH 4.0 was selected as a supporting electrolyte for quantitative purposes by differential pulse and square wave adsorptive cathodic stripping voltammetry. The experimental voltammetric conditions were optimized using Central Composite Face design. A reduction wave was seen in the range from −0.7 to −0.8 V. These voltammetric techniques were successfully validated as per ICH guidelines and applied for the determination of cefoperazone in its single and sulbactam containing powders for injection and statistically comparable to USP-HPLC. They were further extended to determine cefoperazone in spiked human urine with no matrix effect. PMID:24109542

  9. Self-flocculated powdered activated carbon with different oxidation methods and their influence on adsorption behavior.

    PubMed

    Gong, Zailin; Li, Shujin; Ma, Jun; Zhang, Xiangdong

    2016-03-01

    The commercial powdered activated carbon (PAC) has been selectively oxidized by two methods. The two oxidized methods are wet oxidation with ammonium persulfate and thermal treatment after acidification with hydrochloride acid, respectively. The two oxidized PAC were then functionalized with thermoresponsive poly (N-isopropylacrylamide) (PNIPAM) in aqueous solution at ambient temperature. Comparing the two oxidized PAC products and their grafted derivatives, the oxidized PAC modified with thermal treatment after acidification shows larger surface area of 1184 m(2)/g and better adsorption of bisphenol A. Its derivative also exhibits relatively large surface area and adsorption capacity after grafted with PNIPAM. The maximum surface adsorption capacity simulated under Langmuir Models reached 156 mg/g. In addition, the grafted PAC products show self-flocculation behaviors with rapid response to temperature because of the thermal phase transition and entanglement behaviors of PNIPAM. The present study provides a new way to obtain carboxyl-rich activated carbon with large surface area and better adsorption capacity. The retrievable grafted PAC with good self-flocculation effect responsive to temperature will have high potential application in water remediation which requires pre-heating and emergency water treatment in the wild. PMID:26551226

  10. Use of cork powder and granules for the adsorption of pollutants: a review.

    PubMed

    Pintor, Ariana M A; Ferreira, Catarina I A; Pereira, Joana C; Correia, Patrícia; Silva, Susana P; Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2012-06-15

    Cork powder and granules are the major subproducts of the cork industry, one of the leading economic activities in Portugal and other Mediterranean countries. Many applications have been envisaged for this product, from cork stoppers passing through the incorporation in agglomerates and briquettes to the use as an adsorbent in the treatment of gaseous emissions, waters and wastewaters. This paper aims at reviewing the state of the art on the properties of cork and cork powder and their application in adsorption technologies. Cork biomass has been used on its original form as biosorbent for heavy metals and oils, and is also a precursor of activated carbons for the removal of emerging organic pollutants in water and VOCs in the gas phase. Through this literature review, different potential lines of research not yet explored can be more easily identified.

  11. Determination of the adsorptive capacity and adsorption isotherm of vapor-phase mercury chloride on powdered activated carbon using thermogravimetric analysis

    SciTech Connect

    Hsun-Yu Lin; Chung-Shin Yuan; Wei-Ching Chen; Chung-Hsuang Hung

    2006-11-15

    This study investigated the use of thermogravimetric analysis (TGA) to determine the adsorptive capacity and adsorption isotherm of vapor-phase mercury chloride on powdered activated carbon (PAC). The technique is commonly applied to remove mercury-containing air pollutants from gas streams emitted from municipal solid waste incinerators. An alternative form of powdered activated carbon derived from a pyrolyzed tire char was prepared for use herein. The capacity of waste tire-derived PAC to adsorb vapor-phase HgCl{sub 2} was successfully measured using a self-designed TGA adsorption system. Experimental results showed that the maximum adsorptive capacities of HgCl{sub 2} were 1.75, 0.688, and 0.230 mg of HgCl{sub 2} per gram of powdered activated carbon derived from carbon black at 30, 70, and 150{sup o} for 500 {mu}g/m{sup 3} of HgCl{sub 2}, respectively. Four adsorption isotherms obtained using the Langmuir, Freundlich, Redlich-Peterson, and Brunauer-Emmett-eller (BET) models were used to simulate the adsorption of HgCl{sub 2}. The comparison of experimental data associated with the four adsorption isotherms indicated that BET fit the experimental results better than did the other isotherms at 30{sup o}, whereas the Freundlich isotherm fit the experimental results better at 70 and 150{sup o}. Furthermore, the calculations of the parameters associated with Langmuir and Freundlich isotherms revealed that the adsorption of HgCl{sub 2} by PAC-derived carbon black favored adsorption at various HgCl{sub 2} concentrations and temperatures. 35 refs., 7 figs., 3 tabs.

  12. Compact x-ray source and panel

    DOEpatents

    Sampayon, Stephen E.

    2008-02-12

    A compact, self-contained x-ray source, and a compact x-ray source panel having a plurality of such x-ray sources arranged in a preferably broad-area pixelized array. Each x-ray source includes an electron source for producing an electron beam, an x-ray conversion target, and a multilayer insulator separating the electron source and the x-ray conversion target from each other. The multi-layer insulator preferably has a cylindrical configuration with a plurality of alternating insulator and conductor layers surrounding an acceleration channel leading from the electron source to the x-ray conversion target. A power source is connected to each x-ray source of the array to produce an accelerating gradient between the electron source and x-ray conversion target in any one or more of the x-ray sources independent of other x-ray sources in the array, so as to accelerate an electron beam towards the x-ray conversion target. The multilayer insulator enables relatively short separation distances between the electron source and the x-ray conversion target so that a thin panel is possible for compactness. This is due to the ability of the plurality of alternating insulator and conductor layers of the multilayer insulators to resist surface flashover when sufficiently high acceleration energies necessary for x-ray generation are supplied by the power source to the x-ray sources.

  13. X-Ray Diffractive Optics

    NASA Technical Reports Server (NTRS)

    Dennis, Brian; Li, Mary; Skinner, Gerald

    2013-01-01

    X-ray optics were fabricated with the capability of imaging solar x-ray sources with better than 0.1 arcsecond angular resolution, over an order of magnitude finer than is currently possible. Such images would provide a new window into the little-understood energy release and particle acceleration regions in solar flares. They constitute one of the most promising ways to probe these regions in the solar atmosphere with the sensitivity and angular resolution needed to better understand the physical processes involved. A circular slit structure with widths as fine as 0.85 micron etched in a silicon wafer 8 microns thick forms a phase zone plate version of a Fresnel lens capable of focusing approx. =.6 keV x-rays. The focal length of the 3-cm diameter lenses is 100 microns, and the angular resolution capability is better than 0.1 arcsecond. Such phase zone plates were fabricated in Goddard fs Detector Development Lab. (DDL) and tested at the Goddard 600-microns x-ray test facility. The test data verified that the desired angular resolution and throughput efficiency were achieved.

  14. Focused X-ray source

    DOEpatents

    Piestrup, M.A.; Boyers, D.G.; Pincus, C.I.; Maccagno, P.

    1990-08-21

    Disclosed is an intense, relatively inexpensive X-ray source (as compared to a synchrotron emitter) for technological, scientific, and spectroscopic purposes. A conical radiation pattern produced by a single foil or stack of foils is focused by optics to increase the intensity of the radiation at a distance from the conical radiator. 8 figs.

  15. Focused X-ray source

    DOEpatents

    Piestrup, Melvin A.; Boyers, David G.; Pincus, Cary I.; Maccagno, Pierre

    1990-01-01

    An intense, relatively inexpensive X-ray source (as compared to a synchrotron emitter) for technological, scientific, and spectroscopic purposes. A conical radiation pattern produced by a single foil or stack of foils is focused by optics to increase the intensity of the radiation at a distance from the conical radiator.

  16. X-rays and magnetism.

    PubMed

    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.

  17. Alpha proton x ray spectrometer

    NASA Technical Reports Server (NTRS)

    Rieder, Rudi; Waeke, H.; Economou, T.

    1994-01-01

    Mars Pathfinder will carry an alpha-proton x ray spectrometer (APX) for the determination of the elemental chemical composition of Martian rocks and soils. The instrument will measure the concentration of all major and some minor elements, including C, N, and O at levels above typically 1 percent.

  18. X-Ray Diffraction of Intermetallic Compounds: A Physical Chemistry Laboratory Experiment

    ERIC Educational Resources Information Center

    Varberg, Thomas D.; Skakuj, Kacper

    2015-01-01

    Here we describe an experiment for the undergraduate physical chemistry laboratory in which students synthesize the intermetallic compounds AlNi and AlNi3 and study them by X-ray diffractometry. The compounds are synthesized in a simple one-step reaction occurring in the solid state. Powder X-ray diffractograms are recorded for the two compounds…

  19. X-Ray Diffraction on NIF

    SciTech Connect

    Eggert, J H; Wark, J

    2012-02-15

    The National Ignition Facility (NIF) is currently a 192 beam, 1.6 MJ laser. NIF Ramp-Compression Experiments have already made the relevant exo-planet pressure range from 1 to 50 Mbar accessible. We Proposed to Study Carbon Phases by X-Ray Diffraction on NIF. Just a few years ago, ultra-high pressure phase diagrams for materials were very 'simple'. New experiments and theories point out surprising and decidedly complex behavior at the highest pressures considered. High pressures phases of aluminum are also predicted to be complex. Recent metadynamics survey of carbon proposed a dynamic pathway among multiple phases. We need to develop diagnostics and techniques to explore this new regime of highly compressed matter science. X-Ray Diffraction - Understand the phase diagram/EOS/strength/texture of materials to 10's of Mbar. Strategy and physics goals: (1) Powder diffraction; (2) Begin with diamond; (3) Continue with metals etc.; (4) Explore phase diagrams; (5) Develop liquid diffraction; and (6) Reduce background/improve resolution.

  20. X-ray spectrometry and X-ray microtomography techniques for soil and geological samples analysis

    NASA Astrophysics Data System (ADS)

    Kubala-Kukuś, A.; Banaś, D.; Braziewicz, J.; Dziadowicz, M.; Kopeć, E.; Majewska, U.; Mazurek, M.; Pajek, M.; Sobisz, M.; Stabrawa, I.; Wudarczyk-Moćko, J.; Góźdź, S.

    2015-12-01

    A particular subject of X-ray fluorescence analysis is its application in studies of the multielemental sample of composition in a wide range of concentrations, samples with different matrices, also inhomogeneous ones and those characterized with different grain size. Typical examples of these kinds of samples are soil or geological samples for which XRF elemental analysis may be difficult due to XRF disturbing effects. In this paper the WDXRF technique was applied in elemental analysis concerning different soil and geological samples (therapeutic mud, floral soil, brown soil, sandy soil, calcium aluminum cement). The sample morphology was analyzed using X-ray microtomography technique. The paper discusses the differences between the composition of samples, the influence of procedures with respect to the preparation of samples as regards their morphology and, finally, a quantitative analysis. The results of the studies were statistically tested (one-way ANOVA and correlation coefficients). For lead concentration determination in samples of sandy soil and cement-like matrix, the WDXRF spectrometer calibration was performed. The elemental analysis of the samples was complemented with knowledge of chemical composition obtained by X-ray powder diffraction.

  1. X-ray reprocessing in binaries

    NASA Astrophysics Data System (ADS)

    Paul, Biswajit

    2016-07-01

    We will discuss several aspects of X-ray reprocessing into X-rays or longer wavelength radiation in different kinds of binary systems. In high mass X-ray binaries, reprocessing of hard X-rays into emission lines or lower temperature black body emission is a useful tool to investigate the reprocessing media like the stellar wind, clumpy structures in the wind, accretion disk or accretion stream. In low mass X-ray binaries, reprocessing from the surface of the companion star, the accretion disk, warps and other structures in the accretion disk produce signatures in longer wavelength radiation. X-ray sources with temporal structures like the X-ray pulsars and thermonuclear burst sources are key in such studies. We will discuss results from several new investigations of X-ray reprocessing phenomena in X-ray binaries.

  2. Understanding the adsorption mechanism of noble gases Kr and Xe in CPO-27-Ni, CPO-27-Mg, and ZIF-8.

    PubMed

    Magdysyuk, O V; Adams, F; Liermann, H-P; Spanopoulos, I; Trikalitis, P N; Hirscher, M; Morris, R E; Duncan, M J; McCormick, L J; Dinnebier, R E

    2014-11-21

    An experimental study of Xe and Kr adsorption in metal-organic frameworks CPO-27-Ni, CPO-27-Mg, and ZIF-8 was carried out. In situ synchrotron X-ray powder diffraction experiments allowed precise determination of the adsorption sites and sequence of their filling with increasing of gas pressure at different temperatures. Structural investigations were used for interpretation of gas adsorption measurements. PMID:25277596

  3. Center for X-Ray Optics, 1986

    SciTech Connect

    Not Available

    1987-07-01

    The Center for X-Ray Optics has made substantial progress during the past year on the development of very high resolution x-ray technologies, the generation of coherent radiation at x-ray wavelengths, and, based on these new developments, had embarked on several scientific investigations that would not otherwise have been possible. The investigations covered in this report are topics on x-ray sources, x-ray imaging and applications, soft x-ray spectroscopy, synchrotron radiation, advanced light source and magnet structures for undulators and wigglers. (LSP)

  4. X-ray diffraction studies of shocked lunar analogs

    NASA Technical Reports Server (NTRS)

    Hanss, R. E.

    1979-01-01

    The X-ray diffraction experiments on shocked rock and mineral analogs of particular significance to lunar geology are described. Materials naturally shocked by meteorite impact, nuclear-shocked, or artificially shocked in a flat plate accelerator were utilized. Four areas were outlined for investigation: powder diffractometer studies of shocked single crystal silicate minerals (quartz, orthoclase, oligoclase, pyroxene), powder diffractometer studies of shocked polycrystalline monomineralic samples (dunite), Debye-Scherrer studies of single grains of shocked granodiorite, and powder diffractometer studies of shocked whole rock samples. Quantitative interpretation of peak shock pressures experienced by materials found in lunar or terrestrial impact structures is presented.

  5. Microgap x-ray detector

    DOEpatents

    Wuest, Craig R.; Bionta, Richard M.; Ables, Elden

    1994-01-01

    An x-ray detector which provides for the conversion of x-ray photons into photoelectrons and subsequent amplification of these photoelectrons through the generation of electron avalanches in a thin gas-filled region subject to a high electric potential. The detector comprises a cathode (photocathode) and an anode separated by the thin, gas-filled region. The cathode may comprise a substrate, such a beryllium, coated with a layer of high atomic number material, such as gold, while the anode can be a single conducting plane of material, such as gold, or a plane of resistive material, such as chromium/silicon monoxide, or multiple areas of conductive or resistive material, mounted on a substrate composed of glass, plastic or ceramic. The charge collected from each electron avalanche by the anode is passed through processing electronics to a point of use, such as an oscilloscope.

  6. Microgap x-ray detector

    DOEpatents

    Wuest, C.R.; Bionta, R.M.; Ables, E.

    1994-05-03

    An x-ray detector is disclosed which provides for the conversion of x-ray photons into photoelectrons and subsequent amplification of these photoelectrons through the generation of electron avalanches in a thin gas-filled region subject to a high electric potential. The detector comprises a cathode (photocathode) and an anode separated by the thin, gas-filled region. The cathode may comprise a substrate, such a beryllium, coated with a layer of high atomic number material, such as gold, while the anode can be a single conducting plane of material, such as gold, or a plane of resistive material, such as chromium/silicon monoxide, or multiple areas of conductive or resistive material, mounted on a substrate composed of glass, plastic or ceramic. The charge collected from each electron avalanche by the anode is passed through processing electronics to a point of use, such as an oscilloscope. 3 figures.

  7. Hard X-ray astrophysics

    NASA Technical Reports Server (NTRS)

    Rothschild, R. E.

    1981-01-01

    Past hard X-ray and lower energy satellite instruments are reviewed and it is shown that observation above 20 keV and up to hundreds of keV can provide much valuable information on the astrophysics of cosmic sources. To calculate possible sensitivities of future arrays, the efficiencies of a one-atmosphere inch gas counter (the HEAO-1 A-2 xenon filled HED3) and a 3 mm phoswich scintillator (the HEAO-1 A-4 Na1 LED1) were compared. Above 15 keV, the scintillator was more efficient. In a similar comparison, the sensitivity of germanium detectors did not differ much from that of the scintillators, except at high energies where the sensitivity would remain flat and not rise with loss of efficiency. Questions to be addressed concerning the physics of active galaxies and the diffuse radiation background, black holes, radio pulsars, X-ray pulsars, and galactic clusters are examined.

  8. Removal of Cr(III) from chrome tanning wastewater by adsorption using two natural carbonaceous materials: Eggshell and powdered marble.

    PubMed

    Elabbas, Saliha; Mandi, Laila; Berrekhis, Fatima; Pons, Marie Noelle; Leclerc, Jean Pierre; Ouazzani, Naaila

    2016-01-15

    In the present paper, eggshell and powdered marble, two carbonaceous materials, were used to remove Cr(III) ions from a real chrome tanning wastewater. The effects of initial effluent pH, adsorbent dose, contact time and temperature were studied. The maximum uptake of chromium ions was obtained at pH 5.0 with the dose 20 g L(-1) and 12 g L(-1) for eggshell and powdered marble respectively. Adsorption equilibrium was reached after 14 h contact time for eggshell and only after 30 min for powdered marble. Under these conditions, almost 99% Cr(III) was removed from chrome tanning wastewater having an initial concentration of chromium of 3.21 g L(-1). Kinetic data were satisfactorily described by a pseudo-second order chemical sorption model. The equilibrium rate constant was notably greater for powdered marble than for eggshell with 1.142·10(-3) (g mg(-1) min(-1)) and 0.041·10(-3) (g mg(-1) min(-1)) respectively. The adsorption isotherm were well described by a Langmuir model and showed that the interaction of chromium with the two adsorbents surface is a localized monolayer adsorption with a smaller energy constant for the powdered marble than for eggshell (0.020 (L mg(-1)) and 0.083 (L mg(-1)) respectively). The powdered marble was able to adsorb faster a large amount of Cr (III) in comparison to eggshell. The use of a standardized lettuce seed bioassay allowed evaluating a better effectiveness of the Cr adsorption on the powdered marble, removing up to 40% of the treated effluent toxicity than by eggshell 25%. The powdered marble could be considered as an effective, low cost carbonaceous material to be used for chromium removal from tanning wastewater.

  9. Removal of Cr(III) from chrome tanning wastewater by adsorption using two natural carbonaceous materials: Eggshell and powdered marble.

    PubMed

    Elabbas, Saliha; Mandi, Laila; Berrekhis, Fatima; Pons, Marie Noelle; Leclerc, Jean Pierre; Ouazzani, Naaila

    2016-01-15

    In the present paper, eggshell and powdered marble, two carbonaceous materials, were used to remove Cr(III) ions from a real chrome tanning wastewater. The effects of initial effluent pH, adsorbent dose, contact time and temperature were studied. The maximum uptake of chromium ions was obtained at pH 5.0 with the dose 20 g L(-1) and 12 g L(-1) for eggshell and powdered marble respectively. Adsorption equilibrium was reached after 14 h contact time for eggshell and only after 30 min for powdered marble. Under these conditions, almost 99% Cr(III) was removed from chrome tanning wastewater having an initial concentration of chromium of 3.21 g L(-1). Kinetic data were satisfactorily described by a pseudo-second order chemical sorption model. The equilibrium rate constant was notably greater for powdered marble than for eggshell with 1.142·10(-3) (g mg(-1) min(-1)) and 0.041·10(-3) (g mg(-1) min(-1)) respectively. The adsorption isotherm were well described by a Langmuir model and showed that the interaction of chromium with the two adsorbents surface is a localized monolayer adsorption with a smaller energy constant for the powdered marble than for eggshell (0.020 (L mg(-1)) and 0.083 (L mg(-1)) respectively). The powdered marble was able to adsorb faster a large amount of Cr (III) in comparison to eggshell. The use of a standardized lettuce seed bioassay allowed evaluating a better effectiveness of the Cr adsorption on the powdered marble, removing up to 40% of the treated effluent toxicity than by eggshell 25%. The powdered marble could be considered as an effective, low cost carbonaceous material to be used for chromium removal from tanning wastewater. PMID:26598282

  10. X-Ray-powered Macronovae

    NASA Astrophysics Data System (ADS)

    Kisaka, Shota; Ioka, Kunihito; Nakar, Ehud

    2016-02-01

    A macronova (or kilonova) was observed as an infrared excess several days after the short gamma-ray burst GRB 130603B. Although the r-process radioactivity is widely discussed as an energy source, it requires a huge mass of ejecta from a neutron star (NS) binary merger. We propose a new model in which the X-ray excess gives rise to the simultaneously observed infrared excess via thermal re-emission, and explore what constraints this would place on the mass and velocity of the ejecta. This X-ray-powered model explains both the X-ray and infrared excesses with a single energy source such as the central engine like a black hole, and allows for a broader parameter region than the previous models, in particular a smaller ejecta mass ˜ {10}-3{--}{10}-2{M}⊙ and higher iron abundance mixed as suggested by general relativistic simulations for typical NS-NS mergers. We also discuss the other macronova candidates in GRB 060614 and GRB 080503, and the implications for the search of electromagnetic counterparts to gravitational waves.

  11. X-Ray Crystallography Reagent

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

    2003-01-01

    Microcapsules prepared by encapsulating an aqueous solution of a protein, drug or other bioactive substance inside a semi-permeable membrane by are disclosed. The microcapsules are formed by interfacial coacervation under conditions where the shear forces are limited to 0-100 dynes per square centimeter at the interface. By placing the microcapsules in a high osmotic dewatering solution. the protein solution is gradually made saturated and then supersaturated. and the controlled nucleation and crystallization of the protein is achieved. The crystal-filled microcapsules prepared by this method can be conveniently harvested and stored while keeping the encapsulated crystals in essentially pristine condition due to the rugged. protective membrane. Because the membrane components themselves are x-ray transparent, large crystal-containing microcapsules can be individually selected, mounted in x-ray capillary tubes and subjected to high energy x-ray diffraction studies to determine the 3-D smucture of the protein molecules. Certain embodiments of the microcapsules of the invention have composite polymeric outer membranes which are somewhat elastic, water insoluble, permeable only to water, salts, and low molecular weight molecules and are structurally stable in fluid shear forces typically encountered in the human vascular system.

  12. Removal of N-nitrosodimethylamine precursors with powdered activated carbon adsorption.

    PubMed

    Beita-Sandí, Wilson; Ersan, Mahmut Selim; Uzun, Habibullah; Karanfil, Tanju

    2016-01-01

    The main objective of this study was to examine the roles of powdered activated carbon (PAC) characteristics (i.e., surface chemistry, pore size distribution, and surface area) in the removal of N-nitrosodimethylamine (NDMA) formation potential (FP) in surface and wastewater-impacted waters. Also, the effects of natural attenuation of NDMA precursors in surface waters, NDMA FP concentration, and carbon dose on the removal of NDMA FP by PAC were evaluated. Finally, the removal of NDMA FP by PAC at two full-scale DWTPs was monitored. Wastewater-impacted and surface water samples were collected to conduct adsorption experiments using different PACs and activated carbon fibers (ACFs) with a wide range of physicochemical characteristics. The removal efficiency of NDMA FP by PAC was significantly higher in wastewater-impacted than surface waters. Adsorbable NDMA precursors showed a size distribution in the waters tested; the adsorbable fraction included precursors accessing the pore size regions of 10-20 Å and <10 Å. Basic carbons showed higher removal of NDMA FP than acidic carbons on a surface area basis. The overall removal of NDMA FP by PAC on a mass basis depended on the surface area, pore size distribution and pHPZC. Thus, PACs with hybrid characteristics (micro and mesoporous), higher surface areas, and basic surface chemistry are more likely to be effective for NDMA precursor control by PAC adsorption. The application of PAC in DWTPs for taste and odor control resulted in an additional 20% removal of NDMA FP for the PAC doses of 7-10 mg/L. The natural attenuation of NDMA precursors through a combination of processes (biodegradation, photolysis and adsorption) decreased their adsorbability and removal by PAC adsorption.

  13. Removal of N-nitrosodimethylamine precursors with powdered activated carbon adsorption.

    PubMed

    Beita-Sandí, Wilson; Ersan, Mahmut Selim; Uzun, Habibullah; Karanfil, Tanju

    2016-01-01

    The main objective of this study was to examine the roles of powdered activated carbon (PAC) characteristics (i.e., surface chemistry, pore size distribution, and surface area) in the removal of N-nitrosodimethylamine (NDMA) formation potential (FP) in surface and wastewater-impacted waters. Also, the effects of natural attenuation of NDMA precursors in surface waters, NDMA FP concentration, and carbon dose on the removal of NDMA FP by PAC were evaluated. Finally, the removal of NDMA FP by PAC at two full-scale DWTPs was monitored. Wastewater-impacted and surface water samples were collected to conduct adsorption experiments using different PACs and activated carbon fibers (ACFs) with a wide range of physicochemical characteristics. The removal efficiency of NDMA FP by PAC was significantly higher in wastewater-impacted than surface waters. Adsorbable NDMA precursors showed a size distribution in the waters tested; the adsorbable fraction included precursors accessing the pore size regions of 10-20 Å and <10 Å. Basic carbons showed higher removal of NDMA FP than acidic carbons on a surface area basis. The overall removal of NDMA FP by PAC on a mass basis depended on the surface area, pore size distribution and pHPZC. Thus, PACs with hybrid characteristics (micro and mesoporous), higher surface areas, and basic surface chemistry are more likely to be effective for NDMA precursor control by PAC adsorption. The application of PAC in DWTPs for taste and odor control resulted in an additional 20% removal of NDMA FP for the PAC doses of 7-10 mg/L. The natural attenuation of NDMA precursors through a combination of processes (biodegradation, photolysis and adsorption) decreased their adsorbability and removal by PAC adsorption. PMID:26584342

  14. Soft X-ray spectroscopy studies of adsorption and reaction of CO in the presence of H2 over 6 nm MnO nanoparticles supported on mesoporous Co3O4

    NASA Astrophysics Data System (ADS)

    Ralston, Walter T.; Musselwhite, Nathan; Kennedy, Griffin; An, Kwangjin; Horowitz, Yonatan; Cordones, Amy A.; Rude, Bruce; Ahmed, Musahid; Melaet, Gerome; Alayoglu, Selim

    2016-06-01

    MnO nanoparticles (6 nm) were supported on mesoporous spinel Co3O4 and studied using ambient pressure X-ray photoelectron spectroscopy (APXPS) and in situ X-ray absorption spectroscopy (XAS) during hydrogenation of CO. The nature and evolution of surface adsorbed species as well as the oxidation states of the metal oxide surfaces were evaluated under oxidizing, reducing, and H2 + CO (2:1) reaction atmospheres. From APXPS, MnO nanoparticle surfaces were found to be progressively reduced in H2 atmospheres with increasing temperature. Surface adsorbed CO was found to be formed at the expense of lattice O under H2 + CO reaction conditions. In situ XAS indicated that the dominant oxide species were Co(OH)2, Co (II) oxides, MnO, and Mn3O4 under reaction conditions. In situ XAS also indicated the formation of gas phase CO2, the disappearance of lattice O, and the further reduction of Mn3O4 to MnO upon prolonged reaction in H2 + CO. Mass spectroscopy measurements showed the formation of CO2 and hydrocarbons. The spent catalyst was investigated using scanning transmission X-ray microscopy and (scanning) transmission electron microscopy; the catalyst grains were found to be homogeneous.

  15. Trinuclear Zinc(II) Complexes and Polymeric Cadmium(II) Complexes with the Ligand 2,5-Bis(2-pyridyl)pyrazine: Synthesis, Spectral Analysis, and Single-Crystal and Powder X-ray Analyses.

    PubMed

    Neels, Antonia; Stoeckli-Evans, Helen

    1999-12-27

    coordination about the metal is best described as a distorted octahedral with four long distances in the basal plane, to two chlorines and to two nitrogen atoms, and two short distances in the axial direction, to two nitrogen atoms. With Cd(II) two polymeric complexes, 4 and 5 were obtained. Compound 4, C(18)H(16)N(4)O(4)Cd.5H(2)O, crystallizes in the triclinic space group P&onemacr;, a = 9.045(1) Å, b = 10.438(1) Å, c = 12.719(1) Å, alpha = 100.48(1) degrees, beta = 95.05(1) degrees, gamma = 95.86(1) degrees, and Z = 2; R1 for 3694 observed reflections [I > 2sigma(I)] was 0.029. The analogous Cd(NO(3))(2) complex with bppz, 5, could only be obtained in microcrystalline form, and its structure was solved by the use of X-ray powder diffraction methods. Compound 5, C(14)H(10)N(6)O(6)Cd, crystallizes in the monoclinic space group C2/c, with a = 11.6601(3) Å, b = 11.9870(3) Å, c = 12.1453(3) Å, beta = 103.348(2) degrees, and Z = 4. In both 4 and 5 the cadmium atoms are bridged by the ligand bppz, so forming uniform one-dimensional coordination polymers. The cadmium ions exhibit the rare coordination number of 8, with two coordinated ligand molecules and two chelating acetate (4) or nitrate (5) groups. PMID:11671328

  16. Aspergillosis - chest x-ray (image)

    MedlinePlus

    ... usually occurs in immunocompromised individuals. Here, a chest x-ray shows that the fungus has invaded the lung ... are usually seen as black areas on an x-ray. The cloudiness on the left side of this ...

  17. Tuberculosis, advanced - chest x-rays (image)

    MedlinePlus

    ... tissue, and can cause tissue death. These chest x-rays show advanced pulmonary tuberculosis. There are multiple light ... location of cavities within these light areas. The x-ray on the left clearly shows that the opacities ...

  18. Producing X-rays at the APS

    ScienceCinema

    None

    2016-07-12

    An introduction and overview of the Advanced Photon Source at Argonne National Laboratory, the technology that produces the brightest X-ray beams in the Western Hemisphere, and the research carried out by scientists using those X-rays.

  19. Producing X-rays at the APS

    SciTech Connect

    2011-01-01

    An introduction and overview of the Advanced Photon Source at Argonne National Laboratory, the technology that produces the brightest X-ray beams in the Western Hemisphere, and the research carried out by scientists using those X-rays.

  20. Phase-sensitive X-ray imager

    DOEpatents

    Baker, Kevin Louis

    2013-01-08

    X-ray phase sensitive wave-front sensor techniques are detailed that are capable of measuring the entire two-dimensional x-ray electric field, both the amplitude and phase, with a single measurement. These Hartmann sensing and 2-D Shear interferometry wave-front sensors do not require a temporally coherent source and are therefore compatible with x-ray tubes and also with laser-produced or x-pinch x-ray sources.

  1. Bisphenol A removal by combination of powdered activated carbon adsorption and ultrafiltration

    NASA Astrophysics Data System (ADS)

    Wang, Rongchang; Tong, Hao; Xia, Siqing; Zhang, Yalei; Zhao, Jianfu

    2010-11-01

    Bisphenol A (BPA) removal from surface water in the presence of natural organic matter (NOM) by combination of powdered activated carbon (PAC) adsorption and ultrafiltration (UF) was investigated in this study. It was especially focused on the effects of various factors on BPA removal, such as PAC dosage, NOM concentration and pH value. BPA removal by UF+PAC process increased sharply from 4% to 92%, when PAC dosage increased from 0 to 120 mg/L. The optimal PAC dosage was determined to be 30 mg/L. The results also showed that BPA retention was slightly favored in the presence of NOM. As pH increased from 7.0 to 10.5, BPA removal substantially decreased from 90% to 59%. PAC+UF process is recommended to be used as an emergence facility in drinking water treatment, especially when an accidental spilling of deleterious substance, e.g., BPA, in the water resources happens.

  2. Center for X-ray Optics, 1988

    SciTech Connect

    Not Available

    1989-04-01

    This report briefly reviews the following topics: soft-x-ray imaging; reflective optics for hard x-rays; coherent XUV sources; spectroscopy with x-rays; detectors for coronary artery imaging; synchrotron-radiation optics; and support for the advanced light source.

  3. Student X-Ray Fluorescence Experiments

    ERIC Educational Resources Information Center

    Fetzer, Homer D.; And Others

    1975-01-01

    Describes the experimental arrangement for x-ray analysis of samples which involves the following: the radioisotopic x-ray disk source; a student-built fluorescence chamber; the energy dispersive x-ray detector, linear amplifier and bias supply; and a multichannel pulse height analyzer. (GS)

  4. Cryotomography x-ray microscopy state

    DOEpatents

    Le Gros, Mark; Larabell, Carolyn A.

    2010-10-26

    An x-ray microscope stage enables alignment of a sample about a rotation axis to enable three dimensional tomographic imaging of the sample using an x-ray microscope. A heat exchanger assembly provides cooled gas to a sample during x-ray microscopic imaging.

  5. Cosmic X-ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, D.; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1987-01-01

    The soft X-ray sky survey data are combined with the results from the UXT sounding rocket payload. Very strong constraints can then be placed on models of the origin of the soft diffuse background. Additional observational constraints force more complicated and realistic models. Significant progress was made in the extraction of more detailed spectral information from the UXT data set. Work was begun on a second generation proportional counter response model. The first flight of the sounding rocket will have a collimator to study the diffuse background.

  6. Characteristics of competitive adsorption between 2-methylisoborneol and natural organic matter on superfine and conventionally sized powdered activated carbons.

    PubMed

    Matsui, Yoshihiko; Yoshida, Tomoaki; Nakao, Soichi; Knappe, Detlef R U; Matsushita, Taku

    2012-10-01

    When treating water with activated carbon, natural organic matter (NOM) is not only a target for adsorptive removal but also an inhibitory substance that reduces the removal efficiency of trace compounds, such as 2-methylisoborneol (MIB), through adsorption competition. Recently, superfine (submicron-sized) activated carbon (SPAC) was developed by wet-milling commercially available powdered activated carbon (PAC) to a smaller particle size. It was reported that SPAC has a larger NOM adsorption capacity than PAC because NOM mainly adsorbs close to the external adsorbent particle surface (shell adsorption mechanism). Thus, SPAC with its larger specific external surface area can adsorb more NOM than PAC. The effect of higher NOM uptake on the adsorptive removal of MIB has, however, not been investigated. Results of this study show that adsorption competition between NOM and MIB did not increase when NOM uptake increased due to carbon size reduction; i.e., the increased NOM uptake by SPAC did not result in a decrease in MIB adsorption capacity beyond that obtained as a result of NOM adsorption by PAC. A simple estimation method for determining the adsorbed amount of competing NOM (NOM that reduces MIB adsorption) is presented based on the simplified equivalent background compound (EBC) method. Furthermore, the mechanism of adsorption competition is discussed based on results obtained with the simplified EBC method and the shell adsorption mechanism. Competing NOM, which likely comprises a small portion of NOM, adsorbs in internal pores of activated carbon particles as MIB does, thereby reducing the MIB adsorption capacity to a similar extent regardless of adsorbent particle size. SPAC application can be advantageous because enhanced NOM removal does not translate into less effective removal of MIB. Molecular size distribution data of NOM suggest that the competing NOM has a molecular weight similar to that of the target compound. PMID:22763287

  7. X-ray Spectroscopy of Cooling Cluster

    SciTech Connect

    Peterson, J.R.; Fabian, A.C.; /Cambridge U., Inst. of Astron.

    2006-01-17

    We review the X-ray spectra of the cores of clusters of galaxies. Recent high resolution X-ray spectroscopic observations have demonstrated a severe deficit of emission at the lowest X-ray temperatures as compared to that expected from simple radiative cooling models. The same observations have provided compelling evidence that the gas in the cores is cooling below half the maximum temperature. We review these results, discuss physical models of cooling clusters, and describe the X-ray instrumentation and analysis techniques used to make these observations. We discuss several viable mechanisms designed to cancel or distort the expected process of X-ray cluster cooling.

  8. Comets: mechanisms of x-ray activity

    NASA Astrophysics Data System (ADS)

    Ibadov, Subhon

    2016-07-01

    Basic mechanisms of X-ray activity of comets are considered, including D-D mechanism corresponding to generation of X-rays due to production of hot short-living plasma clumps at high-velocity collisions between cometary and interplanetary dust particles as well as M-M one corresponding to production of X-rays due to recombination of multicharge ions of solar wind plasma via charge exchange process at their collisions with molecules/atoms of the cometary atmospheres. Peculiarities of the variation of the comet X-ray spectrum and X-ray luminosity with variation of its heliocentric distance are revealed.

  9. X-ray transmissive debris shield

    DOEpatents

    Spielman, R.B.

    1996-05-21

    An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

  10. X-ray transmissive debris shield

    DOEpatents

    Spielman, Rick B.

    1996-01-01

    An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

  11. X-ray imaging for palaeontology.

    PubMed

    Hohenstein, P

    2004-05-01

    Few may be aware that X-ray imaging is used in palaeontology and has been used since as early as 1896. The X-raying, preparation and exposure of Hunsrück slate fossils are described. Hospital X-ray machines are used by the author in his work. An X-ray is vital to provide evidence that preparation of a slate is worthwhile as well as to facilitate preparation even if there is little external sign of what lies within. The beauty of the X-ray exposure is an added bonus.

  12. Ionospheric effects of solar x-rays

    NASA Astrophysics Data System (ADS)

    Danskin, Donald

    2016-07-01

    The ionospheric absorption of radio waves caused by solar x-ray bursts is measured directly by Riometers from the Canada Riometer Array. The absorption is found to be proportional to the square root of the flux intensity of the X-ray burst with time delays of 18-20 seconds between the peak X-ray emission and absorption in the ionosphere. A detailed analysis showed that some X-ray flares during 2011-2014 are more effective at producing absorption than others. Solar longitude of X-ray burst for several X-class flares shows no consistent pattern of enhancement in the absorption.

  13. Atmospheric electron x-ray spectrometer

    NASA Technical Reports Server (NTRS)

    Feldman, Jason E. (Inventor); George, Thomas (Inventor); Wilcox, Jaroslava Z. (Inventor)

    2002-01-01

    The present invention comprises an apparatus for performing in-situ elemental analyses of surfaces. The invention comprises an atmospheric electron x-ray spectrometer with an electron column which generates, accelerates, and focuses electrons in a column which is isolated from ambient pressure by a:thin, electron transparent membrane. After passing through the membrane, the electrons impinge on the sample in atmosphere to generate characteristic x-rays. An x-ray detector, shaping amplifier, and multi-channel analyzer are used for x-ray detection and signal analysis. By comparing the resultant data to known x-ray spectral signatures, the elemental composition of the surface can be determined.

  14. X-ray lithography using holographic images

    DOEpatents

    Howells, Malcolm R.; Jacobsen, Chris

    1995-01-01

    A non-contact X-ray projection lithography method for producing a desired X-ray image on a selected surface of an X-ray-sensitive material, such as photoresist material on a wafer, the desired X-ray image having image minimum linewidths as small as 0.063 .mu.m, or even smaller. A hologram and its position are determined that will produce the desired image on the selected surface when the hologram is irradiated with X-rays from a suitably monochromatic X-ray source of a selected wavelength .lambda.. On-axis X-ray transmission through, or off-axis X-ray reflection from, a hologram may be used here, with very different requirements for monochromaticity, flux and brightness of the X-ray source. For reasonable penetration of photoresist materials by X-rays produced by the X-ray source, the wavelength X, is preferably chosen to be no more than 13.5 nm in one embodiment and more preferably is chosen in the range 1-5 nm in the other embodiment. A lower limit on linewidth is set by the linewidth of available microstructure writing devices, such as an electron beam.

  15. A single crystal X-ray and powder neutron diffraction study on NASICON-type Li1+xAlxTi2-x(PO4)3 (0 ≤ x ≤ 0.5) crystals: Implications on ionic conductivity

    NASA Astrophysics Data System (ADS)

    Redhammer, G. J.; Rettenwander, D.; Pristat, S.; Dashjav, E.; Kumar, C. M. N.; Topa, D.; Tietz, F.

    2016-10-01

    Single crystals of NASICON-type material Li1+xTi2-xAlx(PO4)3 (LATP) with 0 ≤ x ≤ 0.5 were successfully grown using long-term sintering techniques. Sample material was studied by chemical analysis, single crystal X-ray and neutron diffraction. The Ti4+ replacement scales very well with the Al3+ and Li+ incorporation. The additional Li+ thereby enters the M3 cavity of the NASICON framework at x, y, z ∼ (0.07, 0.34, 0.09) and is regarded to be responsible for the enhanced Li+ conduction of LATP as compared to Al-free LTP. Variations in structural parameters, associated with the Ti4+ substitution with Al3+ + Li+ will be discussed in detail in this paper.

  16. Extended range X-ray telescope

    NASA Technical Reports Server (NTRS)

    Hoover, R. B. (Inventor)

    1981-01-01

    An X-ray telescope system is described which is comprised of a tubular mount having a collecting region remote from the one axial end. A soft X-ray/XUV subsystem associated with the collecting region directs only relatively soft, near on-axis X-rays/XUV radiation incident on a first portion of the collecting region into a first detector sensitive to relatively soft X-rays/XUV radiation. A hard X-ray subsystem associated with the collecting region directs only relatively hard near on-axis X-rays incident on a second portion of the collecting region into a second detector sensitive to relatively hard X-rays.

  17. Evolution of X-ray astronomy

    NASA Technical Reports Server (NTRS)

    Rossj, B.

    1981-01-01

    The evolution of X-ray astronomy up to the launching of the Einstein observatory is presented. The evaluation proceeded through the following major steps: (1) discovery of an extrasolar X-ray source, Sco X-1, orders of magnitude stronger than astronomers believed might exist; (2) identification of a strong X-ray source with the Crab Nebula; (3) identification of Sco X-1 with a faint, peculiar optical object; (4) demonstration that X-ray stars are binary systems, each consisting of a collapsed object accreting matter from an ordinary star; (5) discovery of X-ray bursts; (6) discovery of exceedingly strong X-ray emission from active galaxies, quasars and clusters of galaxies; (7) demonstration that the principal X-ray source is a hot gas filling the space between galaxies.

  18. On stellar X-ray emission

    NASA Technical Reports Server (NTRS)

    Rosner, R.; Golub, L.; Vaiana, G. S.

    1985-01-01

    Stellar X-ray astronomy represents an entirely new astronomical discipline which has emerged during the past five years. It lies at the crossroads of solar physics, stellar physics, and general astrophysics. The present review is concerned with the main physical problems which arise in connection with a study of the stellar X-ray data. A central issue is the extent to which the extrapolation from solar physics is justified and the definition (if possible) of the limits to such extrapolation. The observational properties of X-ray emission from stars are considered along with the solar analogy and the modeling of X-ray emission from late-type stars, the modeling of X-ray emission from early-type stars, the physics of stellar X-ray emission, stellar X-ray emission in the more general astrophysical context, and future prospects.

  19. X ray imaging microscope for cancer research

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Shealy, David L.; Brinkley, B. R.; Baker, Phillip C.; Barbee, Troy W., Jr.; Walker, Arthur B. C., Jr.

    1991-01-01

    The NASA technology employed during the Stanford MSFC LLNL Rocket X Ray Spectroheliograph flight established that doubly reflecting, normal incidence multilayer optics can be designed, fabricated, and used for high resolution x ray imaging of the Sun. Technology developed as part of the MSFC X Ray Microscope program, showed that high quality, high resolution multilayer x ray imaging microscopes are feasible. Using technology developed at Stanford University and at the DOE Lawrence Livermore National Laboratory (LLNL), Troy W. Barbee, Jr. has fabricated multilayer coatings with near theoretical reflectivities and perfect bandpass matching for a new rocket borne solar observatory, the Multi-Spectral Solar Telescope Array (MSSTA). Advanced Flow Polishing has provided multilayer mirror substrates with sub-angstrom (rms) smoothnesss for the astronomical x ray telescopes and x ray microscopes. The combination of these important technological advancements has paved the way for the development of a Water Window Imaging X Ray Microscope for cancer research.

  20. X-ray deconvolution microscopy

    PubMed Central

    Ehn, Sebastian; Epple, Franz Michael; Fehringer, Andreas; Pennicard, David; Graafsma, Heinz; Noël, Peter; Pfeiffer, Franz

    2016-01-01

    Recent advances in single-photon-counting detectors are enabling the development of novel approaches to reach micrometer-scale resolution in x-ray imaging. One example of such a technology are the MEDIPIX3RX-based detectors, such as the LAMBDA which can be operated with a small pixel size in combination with real-time on-chip charge-sharing correction. This characteristic results in a close to ideal, box-like point spread function which we made use of in this study. The proposed method is based on raster-scanning the sample with sub-pixel sized steps in front of the detector. Subsequently, a deconvolution algorithm is employed to compensate for blurring introduced by the overlap of pixels with a well defined point spread function during the raster-scanning. The presented approach utilizes standard laboratory x-ray equipment while we report resolutions close to 10 μm. The achieved resolution is shown to follow the relationship pn with the pixel-size p of the detector and the number of raster-scanning steps n. PMID:27446649

  1. X-ray omni microscopy.

    PubMed

    Paganin, D; Gureyev, T E; Mayo, S C; Stevenson, A W; Nesterets, Ya I; Wilkins, S W

    2004-06-01

    The science of wave-field phase retrieval and phase measurement is sufficiently mature to permit the routine reconstruction, over a given plane, of the complex wave-function associated with certain coherent forward-propagating scalar wave-fields. This reconstruction gives total knowledge of the information that has been encoded in the complex wave-field by passage through a sample of interest. Such total knowledge is powerful, because it permits the emulation in software of the subsequent action of an infinite variety of coherent imaging systems. Such 'virtual optics', in which software forms a natural extension of the 'hardware optics' in an imaging system, may be useful in contexts such as quantitative atom and X-ray imaging, in which optical elements such as beam-splitters and lenses can be realized in software rather than optical hardware. Here, we develop the requisite theory to describe such hybrid virtual-physical imaging systems, which we term 'omni optics' because of their infinite flexibility. We then give an experimental demonstration of these ideas by showing that a lensless X-ray point projection microscope can, when equipped with the appropriate software, emulate an infinite variety of optical imaging systems including those which yield interferograms, Zernike phase contrast, Schlieren imaging and diffraction-enhanced imaging.

  2. X-ray deconvolution microscopy.

    PubMed

    Ehn, Sebastian; Epple, Franz Michael; Fehringer, Andreas; Pennicard, David; Graafsma, Heinz; Noël, Peter; Pfeiffer, Franz

    2016-04-01

    Recent advances in single-photon-counting detectors are enabling the development of novel approaches to reach micrometer-scale resolution in x-ray imaging. One example of such a technology are the MEDIPIX3RX-based detectors, such as the LAMBDA which can be operated with a small pixel size in combination with real-time on-chip charge-sharing correction. This characteristic results in a close to ideal, box-like point spread function which we made use of in this study. The proposed method is based on raster-scanning the sample with sub-pixel sized steps in front of the detector. Subsequently, a deconvolution algorithm is employed to compensate for blurring introduced by the overlap of pixels with a well defined point spread function during the raster-scanning. The presented approach utilizes standard laboratory x-ray equipment while we report resolutions close to 10 μm. The achieved resolution is shown to follow the relationship [Formula: see text] with the pixel-size p of the detector and the number of raster-scanning steps n. PMID:27446649

  3. Adsorption of ciprofloxacin, bisphenol and 2-chlorophenol on electrospun carbon nanofibers: in comparison with powder activated carbon.

    PubMed

    Li, Xiaona; Chen, Shuo; Fan, Xinfei; Quan, Xie; Tan, Feng; Zhang, Yaobin; Gao, Jinsuo

    2015-06-01

    Carbon nanofibers (CNFs) were prepared by electrospun polyacrylonitrile (PAN) polymer solutions followed by thermal treatment. For the first time, the influence of stabilization procedure on the structure properties of CNFs was explored to improve the adsorption capacity of CNFs towards the environmental pollutants from aqueous solution. The adsorption of three organic chemicals including ciprofloxacin (CIP), bisphenol (BPA) and 2-chlorophenol (2-CP) on electrospun CNFs with high surface area of 2326m(2)/g and micro/mesoporous structure characteristics were investigated. The adsorption affinities were compared with that of the commercial powder activated carbon (PAC). The adsorption kinetics and isotherms showed that the maximum adsorption capacities (qm) of CNFs towards the three pollutants are sequenced in the order of CIP>BPA>2-CP, which are 2.6-fold (CIP), 1.6-fold (BPA) and 1.1-fold (2-CP) increase respectively in comparison with that of PAC adsorption. It was assumed that the micro/mesoporous structure of CNFs, molecular size of the pollutants and the π electron interaction play important roles on the high adsorption capacity exhibited by CNFs. In addition, electrostatic interaction and hydrophobic interaction also contribute to the adsorption of CNFs. This study demonstrates that the electrospun CNFs are promising adsorbents for the removal of pollutants from aqueous solutions.

  4. X-ray diffraction-based electronic structure calculations and experimental x-ray analysis for medical and materials applications

    NASA Astrophysics Data System (ADS)

    Mahato, Dip Narayan

    This thesis includes x-ray experiments for medical and materials applications and the use of x-ray diffraction data in a first-principles study of electronic structures and hyperfine properties of chemical and biological systems. Polycapillary focusing lenses were used to collect divergent x rays emitted from conventional x-ray tubes and redirect them to form an intense focused beam. These lenses are routinely used in microbeam x-ray fluorescence analysis. In this thesis, their potential application to powder diffraction and focused beam orthovoltage cancer therapy has been investigated. In conventional x-ray therapy, very high energy (˜ MeV) beams are used, partly to reduce the skin dose. For any divergent beam, the dose is necessarily highest at the entry point, and decays exponentially into the tissue. To reduce the skin dose, high energy beams, which have long absorption lengths, are employed, and rotated about the patient to enter from different angles. This necessitates large expensive specialized equipment. A focused beam could concentrate the dose within the patient. Since this is inherently skin dose sparing, lower energy photons could be employed. A primary concern in applying focused beams to therapy is whether the focus would be maintained despite Compton scattering within the tissue. To investigate this, transmission and focal spot sizes as a function of photon energy of two polycapillary focusing lenses were measured. The effects of tissue-equivalent phantoms of different thicknesses on the focal spot size were studied. Scatter fraction and depth dose were calculated. For powder diffraction, the polycapillary optics provide clean Gaussian peaks, which result in angular resolution that is much smaller than the peak width due to the beam convergence. Powder diffraction (also called coherent scatter) without optics can also be used to distinguish between tissue types that, because they have different nanoscale structures, scatter at different angles

  5. Comparative study of GeO2/Ge and SiO2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Mori, Daichi; Oka, Hiroshi; Hosoi, Takuji; Kawai, Kentaro; Morita, Mizuho; Crumlin, Ethan J.; Liu, Zhi; Watanabe, Heiji; Arima, Kenta

    2016-09-01

    The energy difference between the oxide and bulk peaks in X-ray photoelectron spectroscopy (XPS) spectra was investigated for both GeO2/Ge and SiO2/Si structures with thickness-controlled water films. This was achieved by obtaining XPS spectra at various values of relative humidity (RH) of up to ˜15%. The increase in the energy shift is more significant for thermal GeO2 on Ge than for thermal SiO2 on Si above ˜10-4% RH, which is due to the larger amount of water molecules that infiltrate into the GeO2 film to form hydroxyls. Analyzing the origins of this energy shift, we propose that the positive charging of a partially hydroxylated GeO2 film, which is unrelated to X-ray irradiation, causes the larger energy shift for GeO2/Ge than for SiO2/Si. A possible microscopic mechanism of this intrinsic positive charging is the emission of electrons from adsorbed water species in the suboxide layer of the GeO2 film to the Ge bulk, leaving immobile cations or positively charged states in the oxide. This may be related to the reported negative shift of flat band voltages in metal-oxide-semiconductor diodes with an air-exposed GeO2 layer.

  6. High Mass X-ray Binary Pulsars

    NASA Astrophysics Data System (ADS)

    Naik, Sachindra

    2016-07-01

    High Mass X-ray Binaries (HMXBs) are interesting objects that provide a wide range of observational probes to the nature of the two stellar components, accretion process, stellar wind and orbital parameters of the systems. Most of the transient HMXBs are found to Be/X-ray binaries (~67%), consisting of a compact object (neutron star) in orbit around the companion Be star. The orbit of the compact object around the Be star is wide and highly eccentric. Be/X-ray binaries are generally quiescent in X-ray emission. The transient X-ray outbursts seen in these objects are known to be due to interaction between the compact object and the circumstellar disk surrounding the Be star. In the recent years, another class of transient HMXBs have been found which have supergiant companions and show shorter X-ray outbursts. X-ray, infrared and optical observations of these HMXBs provide vital information regarding these systems. The timing and broad-band X-ray spectral properties of a few HMXB pulsars, mainly Be/X-ray binary pulsars during regular X-ray outbursts will be discussed.

  7. Controlling X-rays With Light

    SciTech Connect

    Glover, Ernie; Hertlein, Marcus; Southworth, Steve; Allison, Tom; van Tilborg, Jeroen; Kanter, Elliot; Krassig, B.; Varma, H.; Rude, Bruce; Santra, Robin; Belkacem, Ali; Young, Linda

    2010-08-02

    Ultrafast x-ray science is an exciting frontier that promises the visualization of electronic, atomic and molecular dynamics on atomic time and length scales. A largelyunexplored area of ultrafast x-ray science is the use of light to control how x-rays interact with matter. In order to extend control concepts established for long wavelengthprobes to the x-ray regime, the optical control field must drive a coherent electronic response on a timescale comparable to femtosecond core-hole lifetimes. An intense field is required to achieve this rapid response. Here an intense optical control pulse isobserved to efficiently modulate photoelectric absorption for x-rays and to create an ultrafast transparency window. We demonstrate an application of x-ray transparencyrelevant to ultrafast x-ray sources: an all-photonic temporal cross-correlation measurement of a femtosecond x-ray pulse. The ability to control x-ray/matterinteractions with light will create new opportunities at current and next-generation x-ray light sources.

  8. Diffractive X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    Skinner, Gerald K.

    2010-01-01

    Diffractive X-ray telescopes, using zone plates, phase Fresnel lenses, or related optical elements have the potential to provide astronomers with true imaging capability with resolution many orders of magnitude better than available in any other waveband. Lenses that would be relatively easy to fabricate could have an angular resolution of the order of micro-arc-seconds or even better, that would allow, for example, imaging of the distorted spacetime in the immediate vicinity of the super-massive black holes in the center of active galaxies. What then is precluding their immediate adoption? Extremely long focal lengths, very limited bandwidth, and difficulty stabilizing the image are the main problems. The history, and status of the development of such lenses is reviewed here and the prospects for managing the challenges that they present are discussed.

  9. Ultraluminous X-ray Sources

    NASA Astrophysics Data System (ADS)

    Gladstone, Jeanette

    2012-07-01

    The first black hole was observed almost 50 years ago, ˜ 1 year after Sco X-1 (although its nature was not confirmed for ˜ 11 years). Observations of black holes have been ongoing since then, falling in to two distinct categories; stellar-mass (sMBHs; 3 - 80 M_{⊙}) and super-massive black holes (10^6 - 10^9 M_⊙). The missing link between these two types, intermediate mass black holes, has been the target of many searches due to their cosmological implications. Ultraluminous X-ray sources (ULXs) have been proposed to harbor such objects, but recent observational evidence has strongly suggested that the majority contain sMBHs. However, a handful of the brightest ULXs are so luminous that they defy this explanation. Here we will discuss the nature of both standard ULXs and this new bright subgroup of this population.

  10. Industrial X-Ray Imaging

    NASA Technical Reports Server (NTRS)

    1997-01-01

    In 1990, Lewis Research Center jointly sponsored a conference with the U.S. Air Force Wright Laboratory focused on high speed imaging. This conference, and early funding by Lewis Research Center, helped to spur work by Silicon Mountain Design, Inc. to break the performance barriers of imaging speed, resolution, and sensitivity through innovative technology. Later, under a Small Business Innovation Research contract with the Jet Propulsion Laboratory, the company designed a real-time image enhancing camera that yields superb, high quality images in 1/30th of a second while limiting distortion. The result is a rapidly available, enhanced image showing significantly greater detail compared to image processing executed on digital computers. Current applications include radiographic and pathology-based medicine, industrial imaging, x-ray inspection devices, and automated semiconductor inspection equipment.

  11. [X-ray diffractometry in the analysis of drugs and pharmaceutical forms].

    PubMed

    Bettinetti, G P

    1989-05-01

    As a consequence of the importance of solid drug substance characterization, analytical tools such as X-ray diffractometry (powder and single crystal methods) are usually employed in the pharmaceutical field. The diagnostic power of X-ray powder diffraction in identifying crystalline compounds, even in multicomponent mixtures, and in showing the non-crystalline ones, has brought about the usual characterization through the X-ray powder diffraction pattern of polymorphic, pseudopolymorphic, and amorphous drugs and of some drug-carrier systems such as solid dispersions, glass dispersions, solid surface dispersions, physical mixtures, eutectics, solid solutions, addition and inclusion compounds, etc. Moreover this technique is also used in the qualitative and quantitative analysis both of drug mixtures and dosage forms, and also in the study of relationships between crystal habit and technological characteristics of pharmaceutical formulations. Single crystal methods are employed for calculating the unit cell lenghts and angles, for indexing powder diffraction patterns, and for demonstrating the crystal and molecular structure of the drug. After a picture of the solid state properties and the X-ray characteristics, as well as of the interaction between X-rays and solid matter, the main pharmaceutical applications of X-ray diffraction are described.

  12. Soft x-ray interferometry

    SciTech Connect

    Not Available

    1993-09-01

    The purpose of the soft x-ray interferometry workshop held at Lawrence Berkeley Laboratory was to discuss with the scientific community the proposed technical design of the soft x-ray Fourier-transform spectrometer being developed at the ALS. Different design strategies for the instrument`s components were discussed, as well as detection methods, signal processing issues, and how to meet the manufacturing tolerances that are necessary for the instrument to achieve the desired levels of performance. Workshop participants were encouraged to report on their experiences in the field of Fourier transform spectroscopy. The ALS is developing a Fourier transform spectrometer that is intended to operate up to 100 eV. The motivation is solely improved resolution and not the throughput (Jaquinot) or multiplex (Fellgett) advantage, neither of which apply for the sources and detectors used in this spectral range. The proposed implementation of this is via a Mach-Zehnder geometry that has been (1) distorted from a square to a rhombus to get grazing incidence of a suitable angle for 100 eV and (2) provided with a mirror-motion system to make the path difference between the interfering beams tunable. The experiment consists of measuring the emergent light intensity (I(x)) as a function of the path difference (x). The resolving power of the system is limited by the amount of path difference obtainable that is 1 cm (one million half-waves at 200{angstrom} wavelength) in the design thus allowing a resolving power of one million. The free spectral range of the system is limited by the closeness with which the function I(x) is sampled. It is proposed to illuminate a helium absorption cell with roughly 1%-band-width light from a monochromator thus allowing one hundred aliases without spectral overlap even for sampling of I(x) at one hundredth of the Nyquist frequency.

  13. Scintillator characterization using the LBL Pulsed X-ray Facility

    SciTech Connect

    Moses, W.W.; Derenzo, S.E.; Weber, M.J.; Blankespoor, S.C.; Ho, M.H.; West, A.C.

    1994-10-01

    The authors have developed a bench-top pulsed x-ray system for measuring scintillation properties of compounds in crystal or powdered form. The source is a light-excited x-ray tube that produces 40 x-ray photons (mean energy 18.5 keV) per steradian in each 100 ps fwhm pulse. The repetition rate is adjustable from 0 to 10{sup 7} pulses per second. The fluorescent emanations from the x-ray excited samples are detected with either a sapphire-windowed microchannel plate photomultiplier tube (spectral range 150--650 nm, transit time jitter 40 ps fwhm) or a quartz windowed GaAs(Cs) photomultiplier tube (spectral range 160--930 nm, transit time jitter 4 ns fwhm). Decay time spectra are acquired using a TDC Havina 40 ps fwhm resolution over a 84 ms dynamic range. A computer controlled monochromator can be inserted into the optical path to measure the emission spectrum or wavelength resolved decay time spectrum. A computer controlled sample changer allows up to 64 samples to be measured without intervention.

  14. X-rays for medical use

    NASA Astrophysics Data System (ADS)

    Hessenbruch, A.

    1995-11-01

    1995 is the centenary of the discovery of X-rays by the German physicist Wilhelm C Rontgen. In the past hundred years, the new rays have developed from being unknown to finding application in many walks of life, not least in medicine. This is so much so that in common speech the word `x-ray` refers not to a form of radiation but to an X-ray photograph taken for the purposes of diagnosis (as in: `I had an X-ray done to see if my leg was broken`). X-rays are now used routinely, and they are used both for diagnosis and for therapy. This paper will give an outline of the use of X-rays in medicine throughout our present century.

  15. X-ray transmissive debris shield

    DOEpatents

    Spielman, Rick B.

    1994-01-01

    A composite window structure is described for transmitting x-ray radiation and for shielding radiation generated debris. In particular, separate layers of different x-ray transmissive materials are laminated together to form a high strength, x-ray transmissive debris shield which is particularly suited for use in high energy fluences. In one embodiment, the composite window comprises alternating layers of beryllium and a thermoset polymer.

  16. Handbook of X-ray Astronomy

    NASA Astrophysics Data System (ADS)

    Arnaud, Keith; Smith, Randall; Siemiginowska, Aneta; Ellis, Richard; Huchra, John; Kahn, Steve; Rieke, George; Stetson, Peter B.

    2011-11-01

    Practical guide to X-ray astronomy for graduate students, professional astronomers and researchers. Presenting X-ray optics, basic detector physics and data analysis. It introduces the reduction and calibration of X-ray data, scientific analysis, archives, statistical issues and the particular problems of highly extended sources. The appendices provide reference material often required during data analysis. The handbook web page contains figures and tables: http://xrayastronomyhandbook.com/

  17. Topological X-Rays and MRIs

    ERIC Educational Resources Information Center

    Lynch, Mark

    2002-01-01

    Let K be a compact subset of the interior of the unit disk D in the plane and suppose one can't see through the boundary of D and identify K. However, assume that one can take "topological X-rays" of D which measure the "density" of K along the lines of the X-rays. By taking these X-rays from all directions, a "topological MRI" is generated for…

  18. Lobster-Eye X-Ray Astronomy

    SciTech Connect

    Hudec, R.; Pina, L.; Marsikova, V.; Inneman, A.

    2010-07-15

    We report on technical and astrophysical aspects of Lobster-Eye wide-field X-ray telescopes expected to monitor the sky with high sensitivity and angular resolution of order of 1 arcmin. They will contribute essentially to study of various astrophysical objects such as AGN, SNe, Gamma-ray bursts (GRBs), X-ray flashes (XRFs), galactic binary sources, stars, CVs, X-ray novae, various transient sources, etc.

  19. Applications of soft x-ray lasers

    SciTech Connect

    Skinner, C.H.

    1993-08-01

    The high brightness and short pulse duration of soft x-ray lasers provide unique advantages for novel applications. Imaging of biological specimens using x-ray lasers has been demonstrated by several groups. Other applications to fields such as chemistry, material science, plasma diagnostics, and lithography are beginning to emerge. We review the current status of soft x-ray lasers from the perspective of applications, and present an overview of the applications currently being developed.

  20. X-ray data booklet. Revision

    SciTech Connect

    Vaughan, D.

    1986-04-01

    A compilation of data is presented. Included are properties of the elements, electron binding energies, characteristic x-ray energies, fluorescence yields for K and L shells, Auger energies, energy levels for hydrogen-, helium-, and neonlike ions, scattering factors and mass absorption coefficients, and transmission bands of selected filters. Also included are selected reprints on scattering processes, x-ray sources, optics, x-ray detectors, and synchrotron radiation facilities. (WRF)

  1. High speed x-ray beam chopper

    DOEpatents

    McPherson, Armon; Mills, Dennis M.

    2002-01-01

    A fast, economical, and compact x-ray beam chopper with a small mass and a small moment of inertia whose rotation can be synchronized and phase locked to an electronic signal from an x-ray source and be monitored by a light beam is disclosed. X-ray bursts shorter than 2.5 microseconds have been produced with a jitter time of less than 3 ns.

  2. Observation of femtosecond X-ray interactions with matter using an X-ray-X-ray pump-probe scheme.

    PubMed

    Inoue, Ichiro; Inubushi, Yuichi; Sato, Takahiro; Tono, Kensuke; Katayama, Tetsuo; Kameshima, Takashi; Ogawa, Kanade; Togashi, Tadashi; Owada, Shigeki; Amemiya, Yoshiyuki; Tanaka, Takashi; Hara, Toru; Yabashi, Makina

    2016-02-01

    Resolution in the X-ray structure determination of noncrystalline samples has been limited to several tens of nanometers, because deep X-ray irradiation required for enhanced resolution causes radiation damage to samples. However, theoretical studies predict that the femtosecond (fs) durations of X-ray free-electron laser (XFEL) pulses make it possible to record scattering signals before the initiation of X-ray damage processes; thus, an ultraintense X-ray beam can be used beyond the conventional limit of radiation dose. Here, we verify this scenario by directly observing femtosecond X-ray damage processes in diamond irradiated with extraordinarily intense (∼10(19) W/cm(2)) XFEL pulses. An X-ray pump-probe diffraction scheme was developed in this study; tightly focused double-5-fs XFEL pulses with time separations ranging from sub-fs to 80 fs were used to excite (i.e., pump) the diamond and characterize (i.e., probe) the temporal changes of the crystalline structures through Bragg reflection. It was found that the pump and probe diffraction intensities remain almost constant for shorter time separations of the double pulse, whereas the probe diffraction intensities decreased after 20 fs following pump pulse irradiation due to the X-ray-induced atomic displacement. This result indicates that sub-10-fs XFEL pulses enable conductions of damageless structural determinations and supports the validity of the theoretical predictions of ultraintense X-ray-matter interactions. The X-ray pump-probe scheme demonstrated here would be effective for understanding ultraintense X-ray-matter interactions, which will greatly stimulate advanced XFEL applications, such as atomic structure determination of a single molecule and generation of exotic matters with high energy densities. PMID:26811449

  3. Observation of femtosecond X-ray interactions with matter using an X-ray-X-ray pump-probe scheme.

    PubMed

    Inoue, Ichiro; Inubushi, Yuichi; Sato, Takahiro; Tono, Kensuke; Katayama, Tetsuo; Kameshima, Takashi; Ogawa, Kanade; Togashi, Tadashi; Owada, Shigeki; Amemiya, Yoshiyuki; Tanaka, Takashi; Hara, Toru; Yabashi, Makina

    2016-02-01

    Resolution in the X-ray structure determination of noncrystalline samples has been limited to several tens of nanometers, because deep X-ray irradiation required for enhanced resolution causes radiation damage to samples. However, theoretical studies predict that the femtosecond (fs) durations of X-ray free-electron laser (XFEL) pulses make it possible to record scattering signals before the initiation of X-ray damage processes; thus, an ultraintense X-ray beam can be used beyond the conventional limit of radiation dose. Here, we verify this scenario by directly observing femtosecond X-ray damage processes in diamond irradiated with extraordinarily intense (∼10(19) W/cm(2)) XFEL pulses. An X-ray pump-probe diffraction scheme was developed in this study; tightly focused double-5-fs XFEL pulses with time separations ranging from sub-fs to 80 fs were used to excite (i.e., pump) the diamond and characterize (i.e., probe) the temporal changes of the crystalline structures through Bragg reflection. It was found that the pump and probe diffraction intensities remain almost constant for shorter time separations of the double pulse, whereas the probe diffraction intensities decreased after 20 fs following pump pulse irradiation due to the X-ray-induced atomic displacement. This result indicates that sub-10-fs XFEL pulses enable conductions of damageless structural determinations and supports the validity of the theoretical predictions of ultraintense X-ray-matter interactions. The X-ray pump-probe scheme demonstrated here would be effective for understanding ultraintense X-ray-matter interactions, which will greatly stimulate advanced XFEL applications, such as atomic structure determination of a single molecule and generation of exotic matters with high energy densities.

  4. Symbiotic Stars in X-rays

    NASA Technical Reports Server (NTRS)

    Luna, G. J. M.; Sokoloski, J. L.; Mukai, K.; Nelson, T.

    2014-01-01

    Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. Here we describe the detection with the X-ray Telescope (XRT) on the Swift satellite of 9 white dwarf symbiotics that were not previously known to be X-ray sources and one that was previously detected as a supersoft X-ray source. The 9 new X-ray detections were the result of a survey of 41 symbiotic stars, and they increase the number of symbiotic stars known to be X-ray sources by approximately 30%. Swift/XRT detected all of the new X-ray sources at energies greater than 2 keV. Their X-ray spectra are consistent with thermal emission and fall naturally into three distinct groups. The first group contains those sources with a single, highly absorbed hard component, which we identify as probably coming from an accretion-disk boundary layer. The second group is composed of those sources with a single, soft X-ray spectral component, which likely arises in a region where low-velocity shocks produce X-ray emission, i.e. a colliding-wind region. The third group consists of those sources with both hard and soft X-ray spectral components. We also find that unlike in the optical, where rapid, stochastic brightness variations from the accretion disk typically are not seen, detectable UV flickering is a common property of symbiotic stars. Supporting our physical interpretation of the two X-ray spectral components, simultaneous Swift UV photometry shows that symbiotic stars with harder X-ray emission tend to have stronger UV flickering, which is usually associated with accretion through a disk. To place these new observations in the context of previous work on X-ray emission from symbiotic stars, we modified and extended the alpha/beta/gamma classification scheme for symbiotic-star X-ray spectra that was introduced by Muerset et al. based upon observations with the ROSAT satellite, to include a new sigma classification for sources with

  5. X-ray laser microscope apparatus

    DOEpatents

    Suckewer, Szymon; DiCicco, Darrell S.; Hirschberg, Joseph G.; Meixler, Lewis D.; Sathre, Robert; Skinner, Charles H.

    1990-01-01

    A microscope consisting of an x-ray contact microscope and an optical microscope. The optical, phase contrast, microscope is used to align a target with respect to a source of soft x-rays. The source of soft x-rays preferably comprises an x-ray laser but could comprise a synchrotron or other pulse source of x-rays. Transparent resist material is used to support the target. The optical microscope is located on the opposite side of the transparent resist material from the target and is employed to align the target with respect to the anticipated soft x-ray laser beam. After alignment with the use of the optical microscope, the target is exposed to the soft x-ray laser beam. The x-ray sensitive transparent resist material whose chemical bonds are altered by the x-ray beam passing through the target mater GOVERNMENT LICENSE RIGHTS This invention was made with government support under Contract No. De-FG02-86ER13609 awarded by the Department of Energy. The Government has certain rights in this invention.

  6. Separating Peaks in X-Ray Spectra

    NASA Technical Reports Server (NTRS)

    Nicolas, David; Taylor, Clayborne; Wade, Thomas

    1987-01-01

    Deconvolution algorithm assists in analysis of x-ray spectra from scanning electron microscopes, electron microprobe analyzers, x-ray fluorescence spectrometers, and like. New algorithm automatically deconvolves x-ray spectrum, identifies locations of spectral peaks, and selects chemical elements most likely producing peaks. Technique based on similarities between zero- and second-order terms of Taylor-series expansions of Gaussian distribution and of damped sinusoid. Principal advantage of algorithm: no requirement to adjust weighting factors or other parameters when analyzing general x-ray spectra.

  7. An Imaging X-Ray Polarimetry Mission

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.; Bellazini, Ronaldo; Costa, Enrico; Ramsey, Brian; O'Dell, Steve; Elsner, Ronald; Pavlov, George; Matt, Giorgio; Kaspi, Victoria; Tennant, Allyn; Coppi, Paolo; Wu, Kinwah; Siegmund, Oswald

    2008-01-01

    Technical progress both in x-ray optics and in polarization-sensitive x-ray detectors, which our groups have pioneered, enables a scientifically powerful---yet inexpensive---dedicated mission for imaging x-ray polarimetry. Such a mission is sufficiently sensitive to measure x-ray (linear) polarization for a broad range of cosmic sources --particularly those involving neutron stars, stellar black holes, and supermassive black holes (active galactic nuclei). We describe the technical elements, discuss a mission concept, and synopsize the important physical and astrophysical questions such a mission would address.

  8. An Imaging X-Ray Polarimetry Mission

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.; Bellazini, Ronaldo; Costa, Enrico; Ramsey, Brian; O'Dell, Steve; Tennant, Allyn; Elsner, Ronald; Pavlov, George; Matt, Girogio; Kaspi, Vicky; Coppi, Paolo; Wu, Kinwah; Siegmund, Oswald

    2008-01-01

    Technical progress both in x-ray optics and in polarization-sensitive x-ray detectors, which our groups have pioneered, enables a scientifically powerful - yet inexpensive - dedicated mission for imaging x-ray polarimetry. Such a mission is sufficiently sensitive to measure x-ray (linear) polarization for a broad range of cosmic sources --- particularly those involving neutron stars, stellar black holes, and supermassive black holes (active galactic nuclei). We describe the technical elements, discuss a mission concept, and synopsiz:e the important physical and astrophysical questions such as mission would address.

  9. The Lunar X-ray Observatory (LXO)

    NASA Technical Reports Server (NTRS)

    Porter, F. Scott

    2008-01-01

    X-ray emission from charge exchange recombination between the highly ionized solar wind and neutral material i n Earth's magnetosheath has complicated x-ray observations of celestial objects with x-ray observatories including ROSAT, Chandra, XMM-Newton, and Suzaku. However, the charge-exchange emission can also be used as an important diagnostic of the solar-wind interacting with the magnetosheath. Soft x-ray observations from low-earth orbit or even the highly eccentric orbits of Chandra and XMM-Newton are likely superpositions of the celestial object of interest, the true extra-solar soft x-ray background, geospheric charge exchange, and heliospheric charge exchange. We show that with a small x-ray telescope placed either on the moon, in a similar vein as the Apollo ALSOP instruments, or at a stable orbit near L1, we can begin t o disentangle the complicated emission structure in the soft x-ray band. Here we present initial results of a feasibility study recently funded by NASA t o place a small x-ray telescope on the lunar surface. The telescope operates during lunar night to observe charge exchange interactions between the solar wind and magnetospheric neutrals, between the solar wind and the lunar atmosphere, and an unobstructed view of the soft x-ray background without the geospheric component.

  10. Colloid Coalescence with Focused X Rays

    SciTech Connect

    Weon, B. M.; Kim, J. T.; Je, J. H.; Yi, J. M.; Wang, S.; Lee, W.-K.

    2011-07-01

    We show direct evidence that focused x rays enable us to merge polymer colloidal particles at room temperature. This phenomenon is ascribed to the photochemical scission of colloids with x rays, reducing the molecular weight, glass transition temperature, surface tension, and viscosity of colloids. The observation of the neck bridge growth with time shows that the x-ray-induced colloid coalescence is analogous to viscoelastic coalescence. This finding suggests a feasible protocol of photonic nanofabrication by sintering or welding of polymers, without thermal damage, using x-ray photonics.

  11. X-rays from the youngest stars

    NASA Technical Reports Server (NTRS)

    Feigelson, Eric D.

    1994-01-01

    The X-ray properties of classical and weak-lined T Tauri stars are briefly reviewed, emphasizing recent results from the ROSAT satellite and prospects for ASCA. The interpretation of the high level of T Tauri X-rays as enhanced solar-type magnetic activity is discussed and criticized. The census of X-ray emitters is significantly increasing estimates of galactic star formation efficiency, and X-ray emission may be important for self-regulation of star formation. ASCA images will detect star formation regions out to several kiloparsecs and will study the magnetically heated plasma around T Tauri stars. However, images will often suffer from crowding effects.

  12. [X-ray diagnosis of histiocytosis X].

    PubMed

    Khomenko, A G; Dmitrieva, L I; Khikkel', Kh G; Stepanian, I E

    1988-01-01

    The results of a dynamic x-ray study of 27 patients suffering from histiocytosis X with lung involvement were analyzed; the study was supplemented by CT in 4 cases. X-ray semiotics of the disease was investigated with relation to its stage. X-ray symptom complexes were defined: interstitial, interstitial-granulomatous, and focal (tumorous). The authors have emphasized the fact that the small focal-cystic and pneumothoracic x-ray variants of the disease, described in literature, are not nosological entities but reflect only its stage and complications.

  13. Compound refractive X-ray lens

    DOEpatents

    Nygren, David R.; Cahn, Robert; Cederstrom, Bjorn; Danielsson, Mats; Vestlund, Jonas

    2000-01-01

    An apparatus and method for focusing X-rays. In one embodiment, his invention is a commercial-grade compound refractive X-ray lens. The commercial-grade compound refractive X-ray lens includes a volume of low-Z material. The volume of low-Z material has a first surface which is adapted to receive X-rays of commercially-applicable power emitted from a commercial-grade X-ray source. The volume of low-Z material also has a second surface from which emerge the X-rays of commercially-applicable power which were received at the first surface. Additionally, the commercial-grade compound refractive X-ray lens includes a plurality of openings which are disposed between the first surface and the second surface. The plurality of openings are oriented such that the X-rays of commercially-applicable power which are received at the first surface, pass through the volume of low-Z material and through the plurality openings. In so doing, the X-rays which emerge from the second surface are refracted to a focal point.

  14. Hard X-ray irradiation of cosmic silicate analogs: structural evolution and astrophysical implications

    NASA Astrophysics Data System (ADS)

    Gavilan, L.; Jäger, C.; Simionovici, A.; Lemaire, J. L.; Sabri, T.; Foy, E.; Yagoubi, S.; Henning, T.; Salomon, D.; Martinez-Criado, G.

    2016-03-01

    Context. Protoplanetary disks, interstellar clouds, and active galactic nuclei contain X-ray-dominated regions. X-rays interact with the dust and gas present in such environments. While a few laboratory X-ray irradiation experiments have been performed on ices, X-ray irradiation experiments on bare cosmic dust analogs have been scarce up to now. Aims: Our goal is to study the effects of hard X-rays on cosmic dust analogs via in situ X-ray diffraction. By using a hard X-ray synchrotron nanobeam, we seek to simulate cumulative X-ray exposure on dust grains during their lifetime in these astrophysical environments and provide an upper limit on the effect of hard X-rays on dust grain structure. Methods: We prepared enstatite (MgSiO3) nanograins, which are analogs to cosmic silicates, via the melting-quenching technique. These amorphous grains were then annealed to obtain polycrystalline grains. These were characterized via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) before irradiation. Powder samples were prepared in X-ray transparent substrates and were irradiated with hard X-rays nanobeams (29.4 keV) provided by beamline ID16B of the European Synchrotron Radiation Facility (Grenoble). X-ray diffraction images were recorded in transmission mode, and the ensuing diffractograms were analyzed as a function of the total X-ray exposure time. Results: We detected the amorphization of polycrystalline silicates embedded in an organic matrix after an accumulated X-ray exposure of 6.4 × 1027 eV cm-2. Pure crystalline silicate grains (without resin) do not exhibit amorphization. None of the amorphous silicate samples (pure and embedded in resin) underwent crystallization. We analyze the evolution of the polycrystalline sample embedded in an organic matrix as a function of X-ray exposure. Conclusions: Loss of diffraction peak intensity, peak broadening, and the disappearance of discrete spots and arcs reveal the amorphization

  15. Comparing graphene, carbon nanotubes, and superfine powdered activated carbon as adsorptive coating materials for microfiltration membranes.

    PubMed

    Ellerie, Jaclyn R; Apul, Onur G; Karanfil, Tanju; Ladner, David A

    2013-10-15

    Multi-walled carbon nanotubes (MWCNTs), nano-graphene platelets (NGPs), and superfine powdered activated carbon (S-PAC) were comparatively evaluated for their applicability as adsorptive coatings on microfiltration membranes. The objective was to determine which materials were capable of contaminant removal while causing minimal flux reduction. Methylene blue and atrazine were the model contaminants. When applied as membrane coatings, MWCNTs had minimal retention capabilities for the model contaminants, and S-PAC had the fastest removal. The membrane coating approach was also compared with a stirred vessel configuration, in which the adsorbent was added to a stirred flask preceding the membrane cell. Direct application of the adsorbent to the membrane constituted a greater initial reduction in permeate concentrations of the model contaminants than with the stirred flask setup. All adsorbents except S-PAC showed flux reductions less than 5% after application as thin-layer membrane coatings, and flux recovery after membrane backwashing was greater than 90% for all materials and masses tested. PMID:23911830

  16. Impacts of coagulation on the adsorption of organic micropollutants onto powdered activated carbon in treated domestic wastewater.

    PubMed

    Altmann, Johannes; Zietzschmann, Frederik; Geiling, Eva-Linde; Ruhl, Aki Sebastian; Sperlich, Alexander; Jekel, Martin

    2015-04-01

    The application of powdered activated carbon (PAC) as an advanced wastewater treatment step for the removal of organic micropollutants (OMP) necessitates complete separation of the PAC particles, e.g. by coagulation. In this study, potential positive or negative indirect or direct effects of coagulation on the adsorption of OMPs onto PAC in treated wastewater were investigated. Although the concentration of dissolved organic matter (DOM) was significantly reduced by coagulation, the selective removal of mainly larger DOM components such as biopolymers and humic substances did not improve subsequent OMP adsorption onto PAC, demonstrating that coagulation has minor effects on DOM constituents that are relevant for direct competition or pore blocking. The combination of coagulation and adsorption yielded the sum of the individual removals, as adsorption predominantly affected smaller compounds. While the formation of flocs led to visible incorporation of PAC particles, no significant mass transfer limitations impeded the OMP adsorption. As a result, the dosing sequence of coagulant and PAC is not critical for efficient adsorption of OMPs onto PAC. The relationships between adsorptive OMP removal and corresponding reduction of UV absorption at 254 nm (UVA254) as a promising surrogate correlation for the real-time monitoring and PAC adjustment were affected by coagulation, leading to individual correlations depending on the water composition. Correcting for UVA254 reduction by coagulation produces adsorptive UVA254 removal, which correlates highly with OMP removal for different WWTP effluents and varying coagulant doses and can be applied in combined adsorption/coagulation processes to predict OMP removal and control PAC dosing.

  17. Impacts of coagulation on the adsorption of organic micropollutants onto powdered activated carbon in treated domestic wastewater.

    PubMed

    Altmann, Johannes; Zietzschmann, Frederik; Geiling, Eva-Linde; Ruhl, Aki Sebastian; Sperlich, Alexander; Jekel, Martin

    2015-04-01

    The application of powdered activated carbon (PAC) as an advanced wastewater treatment step for the removal of organic micropollutants (OMP) necessitates complete separation of the PAC particles, e.g. by coagulation. In this study, potential positive or negative indirect or direct effects of coagulation on the adsorption of OMPs onto PAC in treated wastewater were investigated. Although the concentration of dissolved organic matter (DOM) was significantly reduced by coagulation, the selective removal of mainly larger DOM components such as biopolymers and humic substances did not improve subsequent OMP adsorption onto PAC, demonstrating that coagulation has minor effects on DOM constituents that are relevant for direct competition or pore blocking. The combination of coagulation and adsorption yielded the sum of the individual removals, as adsorption predominantly affected smaller compounds. While the formation of flocs led to visible incorporation of PAC particles, no significant mass transfer limitations impeded the OMP adsorption. As a result, the dosing sequence of coagulant and PAC is not critical for efficient adsorption of OMPs onto PAC. The relationships between adsorptive OMP removal and corresponding reduction of UV absorption at 254 nm (UVA254) as a promising surrogate correlation for the real-time monitoring and PAC adjustment were affected by coagulation, leading to individual correlations depending on the water composition. Correcting for UVA254 reduction by coagulation produces adsorptive UVA254 removal, which correlates highly with OMP removal for different WWTP effluents and varying coagulant doses and can be applied in combined adsorption/coagulation processes to predict OMP removal and control PAC dosing. PMID:25582393

  18. The adsorptive capacity of vapor-phase mercury chloride onto powdered activated carbon derived from waste tires

    SciTech Connect

    Hsun-Yu Lin; Chung-Shin Yuan; Chun-Hsin Wu; Chung-Hsuang Hung

    2006-11-15

    Injection of powdered activated carbon (PAC) upstream of particulate removal devices (such as electrostatic precipitator and baghouses) has been used effectively to remove hazardous air pollutants, particularly mercury containing pollutants, emitted from combustors and incinerators. Compared with commercial PACs (CPACs), an alternative PAC derived from waste tires (WPAC) was prepared for this study. The equilibrium adsorptive capacity of mercury chloride (HgCl{sub 2}) vapor onto the WPAC was further evaluated with a self-designed bench-scale adsorption column system. The adsorption temperatures investigated in the adsorption column were controlled at 25 and 150{sup o}C. The superficial velocity and residence time of the flow were 0.01 m/sec and 4 sec, respectively. The adsorption column tests were run under nitrogen gas flow. Experimental results showed that WPAC with higher Brunauer Emmett Teller (BET) surface area could adsorb more HgCl{sub 2} at room temperature. The equilibrium adsorptive capacity of HgCl{sub 2} for WPAC measured in this study was 1.49 x 10{sup -1} mg HgCl{sub 2}/g PAC at 25{sup o}C with an initial HgCl{sub 2} concentration of 25 {mu}g/m{sup 3}. With the increase of adsorption temperature {le} 150{sup o}C, the equilibrium adsorptive capacity of HgCl{sub 2} for WPAC was decreased to 1.34 x 10{sup -1} mg HgCl{sub 2}/g PAC. Furthermore, WPAC with higher sulfur contents could adsorb even more HgCl{sub 2}. It was demonstrated that the mechanisms for adsorbing HgCl{sub 2} onto WPAC were physical adsorption and chemisorption at 25 and 150{sup o}C, respectively. 35 refs., 4 figs., 4 tabs.

  19. X-Ray Imaging Study

    NASA Technical Reports Server (NTRS)

    OBrien, Susan K.; Workman, Gary L.

    1996-01-01

    The space environment in which the Space Station Freedom and other space platforms will orbit is truly a hostile environment. For example, the currently estimated integral fluence for electrons above 1 Mev at 2000 nautical miles is above 2 x 1O(exp 10) electrons/sq cm/day and the proton integral fluence is above 1 x 10(exp 9) protons/sq cm/day. At the 200 - 400 nautical miles, which is more representative of the altitude which will provide the environment for the Space Station, each of these fluences will be proportionally less; however, the data indicates that the radiation environment will obviously have an effect on structural materials exposed to the environment for long durations. The effects of this combined environment is the issue which needs to be understood for the long term exposure of structures in space. At the same time, there will be substantial potential for collisions between the space platforms and space debris. The current NASA catalogue contains over 4500 objects floating in space which are not considered payloads. This debris can have significant effects on collision with orbiting spacecraft. In order to better understand the effect of these hostile phenomena on spacecraft, several types of studies are being performed to simulate at some level the effect of the environment. In particular the study of debris clouds produced by hypervelocity impact on the various surfaces anticipated on the Space Station is very important at this point in time. The need to assess the threat of such debris clouds on space structures is an on-going activity. The Space Debris Impact facility in Building 4612 provides a test facility to monitor the types of damage produced with hypervelocity impact. These facilities are used to simulate space environmental effects from energetic particles. Flash radiography or x-ray imaging has traditionally provided such information and as such has been an important tool for recording damage in situ with the event. The proper

  20. Impacts of ozonation on the competition between organic micro-pollutants and effluent organic matter in powdered activated carbon adsorption.

    PubMed

    Zietzschmann, F; Mitchell, R-L; Jekel, M

    2015-11-01

    This study investigates if ozonation of wastewater treatment plant (WWTP) effluent can reduce the negative impacts of effluent organic matter (EfOM) on the adsorption of organic micro-pollutants (OMP) onto powdered activated carbon (PAC). Pre-treatment of the water included membrane filtration for the removal of suspended/colloidal organics, ozonation with various specific ozone consumptions, and subsequent OMP spiking to comparable initial concentrations in all of the ozonated waters. This approach allowed for comparative PAC adsorption tests. Adsorption analyses show that the adsorbability of EfOM decreases with increasing specific ozone consumptions. This is also reflected by liquid chromatography with online carbon and UV254 detection (LC-OCD) which shows the ozone-induced disintegration of large EfOM into smaller fragments. Also, small organic neutrals are decreased while the small organic acids peak continuously increases with rising specific ozone consumptions. UV254 demonstrates that the aromaticity of all LC-OCD fractions continuously declines together with increasing specific O3 consumptions. This explains the varying EfOM adsorbabilities that occur due to ozonation. The ozone-induced decrease of EfOM adsorbability directly translates into reduced adsorption competition against the adsorption of OMP. With higher specific ozone consumptions, OMP removal and OMP loadings increase. The reduced adsorption competition is reflected in the outputs from equivalent background compound (EBC) modeling. In each of the ozonated waters, correlations between the OMP removals and the UV254 removal were found.

  1. Impacts of ozonation on the competition between organic micro-pollutants and effluent organic matter in powdered activated carbon adsorption.

    PubMed

    Zietzschmann, F; Mitchell, R-L; Jekel, M

    2015-11-01

    This study investigates if ozonation of wastewater treatment plant (WWTP) effluent can reduce the negative impacts of effluent organic matter (EfOM) on the adsorption of organic micro-pollutants (OMP) onto powdered activated carbon (PAC). Pre-treatment of the water included membrane filtration for the removal of suspended/colloidal organics, ozonation with various specific ozone consumptions, and subsequent OMP spiking to comparable initial concentrations in all of the ozonated waters. This approach allowed for comparative PAC adsorption tests. Adsorption analyses show that the adsorbability of EfOM decreases with increasing specific ozone consumptions. This is also reflected by liquid chromatography with online carbon and UV254 detection (LC-OCD) which shows the ozone-induced disintegration of large EfOM into smaller fragments. Also, small organic neutrals are decreased while the small organic acids peak continuously increases with rising specific ozone consumptions. UV254 demonstrates that the aromaticity of all LC-OCD fractions continuously declines together with increasing specific O3 consumptions. This explains the varying EfOM adsorbabilities that occur due to ozonation. The ozone-induced decrease of EfOM adsorbability directly translates into reduced adsorption competition against the adsorption of OMP. With higher specific ozone consumptions, OMP removal and OMP loadings increase. The reduced adsorption competition is reflected in the outputs from equivalent background compound (EBC) modeling. In each of the ozonated waters, correlations between the OMP removals and the UV254 removal were found. PMID:26231581

  2. Long-Term Hard X-Ray Monitoring of X-Ray Bursters

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.; Kaaret, Philip

    1999-01-01

    The scientific goal of this project was to monitor a selected sample of x-ray bursters using data from the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory to characterize the hard x-ray emission of these objects over long time intervals. The project was closely related to "Monitoring x-ray emission from x-ray bursters", NASA project, and "Hard x-ray emission of x-ray bursters", NASA project, and shares publications in common with both of these. These efforts have lead to results directly from the BATSE data and also from Target of Opportunity Observations (TOO) made with the Rossi X-Ray Timing Explorer based on detection of transient hard x-ray outbursts with BATSE. The following papers have used BATSE data or data obtained with BATSE TOO triggers.

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

    SciTech Connect

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

    1998-05-16

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

  4. SN X-ray Progenitor?

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Identifying stars that explode, right before they explode, is a tricky proposition since the end of starlife comes swiftly: in thermonuclear deflagrations, in nuclear exhaustion, or maybe in a rapid swirling merger of two dead stellar cores. On the right in the image above is an image of the galaxy NGC 1404 taken by the UV/optical Telescope (UVOT) on the Swift observatory. The circle surrounds SN 2007on, a supernova of Type Ia produced by the explosion of a white dwarf star in a binary system. These types of supernovae are important since they are believed to be 'standard candles', events which have the same intrinsic brightness which can serve as an important yardstick to measure cosmic distances. On the left is an image of the same galaxy taken by the Chandra X-ray observatory four years before the supernova. Conspicuous in the SN source circle is a bright source in the Chandra image, believed to be emission from a compact object+normal star companion: a similar system to the supposed precursor of SN 2007on. If true this would be the first time a Type Ia supernova precursor has ever been seen. But astronomers are still debating whether the Chandra source really is the precursor or not; it seems there's a slight but significant difference in the location of the Chandra source and the supernova. Stay tuned for more developments.

  5. SMM X-ray polychromator

    NASA Technical Reports Server (NTRS)

    Strong, Keith T.; Haisch, Bernhard M. (Compiler); Lemen, James R. (Compiler); Acton, L. W.; Bawa, H. S.; Claflin, E. S.; Freeland, S. L.; Slater, G. L.; Kemp, D. L.; Linford, G. A.

    1988-01-01

    The range of observing and analysis programs accomplished with the X-Ray Polychromator (XRP) instruments during the decline of solar cycle 21 and the rise of the solar cycle 22 is summarized. Section 2 describes XRP operations and current status. This is meant as a guide on how the instrument is used to obtain data and what its capabilities are for potential users. The science section contains a series of representative abstracts from recently published papers on major XRP science topics. It is not meant to be a complete list but illustrates the type of science that can come from the analysis of the XRP data. There then follows a series of appendixes that summarize the major data bases that are available. Appendix A is a complete bibliography of papers and presentations produced using XRP data. Appendix B lists all the spectroscopic data accumulated by the Flat Crystal Spectrometer (FCS). Appendix C is a compilation of the XRP flare catalogue for events equivalent to a GOES C-level flare or greater. It lists the start, peak and end times as well as the peak Ca XIX flux.

  6. Adsorption properties of ultradispersed powders of aluminum alloys with rare-earth metals, before and after water treatment

    NASA Astrophysics Data System (ADS)

    Ryabina, A. V.; Shevchenko, V. G.; Eselevich, D. A.

    2014-10-01

    Adsorption of nitrogen on Al-3% La, Al-1.5% Sc, and Al-3% Ce powders before and after processing with water in the relative pressure range p/p s = 10˜3 to 0.999 is experimentally studied at a temperature of 78 K. It is shown that the interaction between ultradispersed powder and water depends on the properties of the original powder, including the original content and composition of the oxide-hydroxide phases in the surface layers of metal particles, and the length and conditions of storage. Results confirming that processing powders containing rare-earth metals with water at room temperature leads to the formation of new phases and affects their morphology are presented. It is shown that the nanopores formed between crystallites on the surface of the particles during oxidation with water and subsequent thermal dehydration play an important role in the properties of powders processed with water. The specific surface and the porosity of powders are calculated.

  7. Diffraction leveraged modulation of X-ray pulses using MEMS-based X-ray optics

    DOEpatents

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

    2016-08-09

    A method and apparatus are provided for implementing Bragg-diffraction leveraged modulation of X-ray pulses using MicroElectroMechanical systems (MEMS) based diffractive optics. An oscillating crystalline MEMS device generates a controllable time-window for diffraction of the incident X-ray radiation. The Bragg-diffraction leveraged modulation of X-ray pulses includes isolating a particular pulse, spatially separating individual pulses, and spreading a single pulse from an X-ray pulse-train.

  8. Tracing the X-Ray Trail

    MedlinePlus

    What you need to know about… Tracing the X-ray Trail If you’ve just completed an x-ray, computed tomography (CT), magnetic resonance (MR) Start here! or other diagnostic imaging procedure, you probably want to know when you will ... los rayos X Si acaba de hacerse una radiografía, tomografía ¡Empezar ...

  9. X-ray determination of parts alignment

    NASA Technical Reports Server (NTRS)

    Nelson, C. W.

    1985-01-01

    A method for determining the alignment of adjoining metal objects is provided. The method comprises producing an X-ray image of adjoining surfaces of the two metal objects. The X-ray beam is tangential to the point the surfaces are joined. The method is particularly applicable where the alignment of the two metal objects is not readily susceptible to visual inspection.

  10. X-Ray Determination of Weld Misalinement

    NASA Technical Reports Server (NTRS)

    Nelson, C. W.

    1985-01-01

    Simple technique uses ordinary X-ray equipment. Weld line between hemispheres of hidden spherical pressure vessel examined for misalinement between hemispheres. Central X-ray tangent to pressure vessel at weld line. Technique not limited to spheres. Also used to check alinement between insulated sections of pipelines or chemical-reaction vessels without removing insulation or interrupting flow or process.

  11. X-ray Attenuation and Absorption Calculations.

    1988-02-25

    This point-source, polychromatic, discrete energy X-ray transport and energy deposition code system calculates first-order spectral estimates of X-ray energy transmission through slab materials and the associated spectrum of energy absorbed by the material.

  12. X-rays Flares and Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Feigelson, Eric D.

    2011-04-01

    X-ray observations of star forming regions show that magnetic reconnection flares are powerful and frequent in pre-main sequence solar-type stars. Well-defined samples in the Orion Nebula Cluster and Taurus clouds exhibit flares with peak X- ray luminosities Lx˜10^29 - 10^32 erg/s, orders of magnitude stronger and more frequent than contemporary solar flares. X-rays are emitted in magnetic loops extending 0.1-10 R * above the stellar surface and thus have a favorable geometry to irradiate the protoplanetary disk. Several lines of evidence - fluorescent iron X-ray emission line, forbidden [NeII] infrared line, and excited molecular bands - support X-ray irradiation of cold material in some young systems. Several astrophysical consequences of X-ray irradiation are outlined. As ionization fractions need only reach 10-12 to induce the magnetorotational instability and associated turbulence, X-rays may be the principal determinant of the extent of the viscous "active zone" and laminar "dead zone" in the layered accretion disk. X-ray irradiation may thus play a major role in planet formation processes: particle settling; meter-size inspiral; protoplanetary migration; and dissipation of the gaseous disk.

  13. X-ray dynamical diffraction Fraunhofer holography.

    PubMed

    Balyan, Minas

    2013-09-01

    An X-ray dynamical diffraction Fraunhofer holographic scheme is proposed. Theoretically it is shown that the reconstruction of the object image by visible light is possible. The spatial and temporal coherence requirements of the incident X-ray beam are considered. As an example, the hologram recording as well as the reconstruction by visible light of an absolutely absorbing wire are discussed.

  14. Phased Contrast X-Ray Imaging

    ScienceCinema

    Erin Miller

    2016-07-12

    The Pacific Northwest National Laboratory is developing a range of technologies to broaden the field of explosives detection. Phased contrast X-ray imaging, which uses silicon gratings to detect distortions in the X-ray wave front, may be applicable to mail or luggage scanning for explosives; it can also be used in detecting other contraband, small-parts inspection, or materials characterization.

  15. X-Ray Emissions from Jupiter

    NASA Technical Reports Server (NTRS)

    Gladstone, G. R.; Waite, J. H., Jr.; Grodent, D.; Crary, F. J.; Elsner, R. F.; Weisskopf, M. C.; Lewis, W. S.; Jahn, J.-M.; Bhardwaj, A.; Clarke, J. T.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    X-ray emissions from Jupiter have been observed for over 20 years. Jovian x-ray emissions are associated with high-latitude aurora and with solar fluorescence and/or an energetic particle source at low-latitudes as identified by past Einstein and ROSAT observations. Enhanced auroral x-rays were also observed to be associated with the impact of Comet Shoemaker-Levy 9. The high-latitude x-ray emissions are best explained by energetic sulfur and oxygen ion precipitation from the Jovian magnetosphere, a suggestion that has been confirmed by recent Chandra ACIS observations. Exciting new information about Jovian x-ray emissions has been made possible with Chandra's High Resolution Camera. We report here for the first time the detection of a forty minute oscillation associated with the Jovian x-ray aurora. With the help of ultraviolet auroral observations from Hubble Space Telescope, we pinpoint the auroral mapping of the x-rays and provide new information on the x-ray source mechanism.

  16. Course Manual for X-Ray Applications.

    ERIC Educational Resources Information Center

    Food and Drug Administration (DHEW), Rockville, MD. Bureau of Radiological Health.

    This publication is the third of three sequential course manuals for instructors in x-ray science and engineering. This course manual has been tested by introducing it into the Oregon State University curriculum. The publication is prepared for the purpose of improving the qualifications of x-ray users and to reduce the ionizing radiation exposure…

  17. VETA-1 x ray detection system

    NASA Technical Reports Server (NTRS)

    Podgorski, W. A.; Flanagan, Kathy A.; Freeman, Mark D.; Goddard, R. G.; Kellogg, Edwin M.; Norton, T. J.; Ouellette, J. P.; Roy, A. G.; Schwartz, Daniel A.

    1992-01-01

    The alignment and X-ray imaging performance of the Advanced X-ray Astrophysics Facility (AXAF) Verification Engineering Test Article-I (VETA-I) was measured by the VETA-I X-Ray Detection System (VXDS). The VXDS was based on the X-ray detection system utilized in the AXAF Technology Mirror Assembly (TMA) program, upgraded to meet the more stringent requirements of the VETA-I test program. The VXDS includes two types of X-ray detectors: (1) a High Resolution Imager (HRI) which provides X-ray imaging capabilities, and (2) sealed and flow proportional counters which, in conjunction with apertures of various types and precision translation stages, provide the most accurate measurement of VETA-I performance. Herein we give an overview of the VXDS hardware including X-ray detectors, translation stages, apertures, proportional counters and flow counter gas supply system and associated electronics. We also describe the installation of the VXDS into the Marshall Space Flight Center (MSFC) X-Ray Calibration Facility (XRCF). We discuss in detail the design and performance of those elements of the VXDS which have not been discussed elsewhere; translation systems, flow counter gas supply system, apertures and thermal monitoring system.

  18. Subpicosecond Coherent Manipulation of X-Rays

    SciTech Connect

    Adams, Bernhard W.

    2004-05-12

    The Takagi-Taupin theory is synthesized with the eikonal theory in a unified space-time approach, based upon microscopic electromagnetism. It is designed specifically to address x-ray diffraction in crystal structures being modified within down to a few femtosconds. Possible applications in the subpicosecond coherent manipulation of x-rays are given.

  19. Adenocarcinoma - chest x-ray (image)

    MedlinePlus

    This chest x-ray shows adenocarcinoma of the lung. There is a rounded light spot in the right upper lung (left side ... density. Diseases that may cause this type of x-ray result would be tuberculous or fungal granuloma, and ...

  20. Accelerator-driven X-ray Sources

    SciTech Connect

    Nguyen, Dinh Cong

    2015-11-09

    After an introduction which mentions x-ray tubes and storage rings and gives a brief review of special relativity, the subject is treated under the following topics and subtopics: synchrotron radiation (bending magnet radiation, wiggler radiation, undulator radiation, brightness and brilliance definition, synchrotron radiation facilities), x-ray free-electron lasers (linac-driven X-ray FEL, FEL interactions, self-amplified spontaneous emission (SASE), SASE self-seeding, fourth-generation light source facilities), and other X-ray sources (energy recovery linacs, Inverse Compton scattering, laser wakefield accelerator driven X-ray sources. In summary, accelerator-based light sources cover the entire electromagnetic spectrum. Synchrotron radiation (bending magnet, wiggler and undulator radiation) has unique properties that can be tailored to the users’ needs: bending magnet and wiggler radiation is broadband, undulator radiation has narrow spectral lines. X-ray FELs are the brightest coherent X-ray sources with high photon flux, femtosecond pulses, full transverse coherence, partial temporal coherence (SASE), and narrow spectral lines with seeding techniques. New developments in electron accelerators and radiation production can potentially lead to more compact sources of coherent X-rays.

  1. X-Ray Detection Visits the Classroom

    ERIC Educational Resources Information Center

    Peralta, Luis; Farinha, Ana; Pinto, Ana

    2008-01-01

    Film has been used to detect x-rays since the early days of their discovery by Rontgen. Although nowadays superseded by other techniques, film still provides a cheap means of x-ray detection, making it attractive in high-school or undergraduate university courses. If some sort of quantitative result is required, the film's optical absorbance or…

  2. Coccidioidomycosis - chest x-ray (image)

    MedlinePlus

    This chest x-ray shows the affects of a fungal infection, coccidioidomycosis. In the middle of the left lung (seen on the ... defined borders. Other diseases that may explain these x-ray findings include lung abscesses, chronic pulmonary tuberculosis, chronic ...

  3. The future in X-ray surveys

    NASA Astrophysics Data System (ADS)

    Hasinger, Günther

    2015-08-01

    I will chair this "Way Forward" discusson about the future in X-ray Surveys at the Focus Meeting #6Cosmological X-ray Surveys: probing the Hot and Energetic Cosmos. Participants will be R. Gilli,G. Pratt, G. Fabbiano, X. Barcons, T. Ohashi, F. Harrison.

  4. X-rays from intermediate mass stars

    NASA Astrophysics Data System (ADS)

    Robrade, Jan

    I will review the X-ray properties of intermediate mass stars and discuss possible X-ray generating mechanisms. Main-sequence stars of spectral type mid B to mid A neither drive sufficiently strong winds to produce shock generated X-rays, nor possess an outer convection zone to generate dynamo driven magnetic activity and coronae. Consequently they should be virtually X-ray dark and occasionally detected X-ray emission was usually attributed to undetected low-mass companions. However, in magnetic intermediate mass stars, the Ap/Bp stars, a different X-ray production mechanism may operate. It is termed the magnetically channeled wind-shock model, where the stellar wind from both hemispheres is channelled towards the equatorial plane, collides and forms a rigidly rotating disk around the star. The strong shocks of the nearly head-on wind collision as well as the existence of magnetically confined plasma in a dynamic circumstellar disk can lead to diverse X-ray phenomena. In this sense Ap/Bp stars bridge the 'classical' X-ray regimes of cool and hot stars.

  5. The Advanced X-Ray Astrophysics Facility. Observing the Universe in X-Rays

    NASA Technical Reports Server (NTRS)

    Neal, V.

    1984-01-01

    An overview of the Advanced X ray Astronophysics Facility (AXAF) program is presented. Beginning with a brief introduction to X ray astrophysics, the AXAF observatory is described including the onboard instrumentation and system capabilities. Possible X ray sources suitable for AXAF observation are identified and defined.

  6. Superiority of wet-milled over dry-milled superfine powdered activated carbon for adsorptive 2-methylisoborneol removal.

    PubMed

    Pan, Long; Matsui, Yoshihiko; Matsushita, Taku; Shirasaki, Nobutaka

    2016-10-01

    Superfine powdered activated carbon (SPAC), which is produced from conventionally sized powdered activated carbon (PAC) by wet milling in a bead mill, has attracted attention for its high adsorptive removal ability in both research and practice. In this study, the performance of dry-milled SPAC was investigated. 2-Methylisoborneol (MIB), an earthy-musty compound commonly targeted by water treatment systems, was used as the target adsorbate. Dry-milled SPAC exhibited lower adsorptive removal of MIB than wet-milled SPAC, even when both SPACs were produced from the same PAC and were composed of particles of the same size. One reason for the lower removal of MIB by the dry-milled SPAC was a higher degree of aggregation in the dry-milled SPAC after production; as a result the apparent particle size of dry-milled SPAC was larger than that of wet-milled SPAC. The dry-milled SPAC was also more negatively charged than the wet-milled SPAC, and, owing to its higher repulsion, it was more amenable to dispersion by ultrasonication. However, even after the dry-milled SPAC was ultrasonicated so that its apparent particle size was similar to or less than that of the wet-milled SPAC, the dry-milled SPAC was still inferior in adsorptive removal to the wet-milled SPAC. Therefore, another reason for the lower adsorptive removal of dry-milled SPAC was its lower equilibrium adsorption capacity due to the oxidation during the milling. The adsorption kinetics by SPACs with different degrees of particle aggregation were successfully simulated by a pore diffusion model and a fractal aggregation model. PMID:27403874

  7. White beam x-ray waveguide optics

    SciTech Connect

    Jarre, A.; Salditt, T.; Panzner, T.; Pietsch, U.; Pfeiffer, F.

    2004-07-12

    We report a white beam x-ray waveguide (WG) experiment. A resonant beam coupler x-ray waveguide (RBC) is used simultaneously as a broad bandpass (or multibandpass) monochromator and as a beam compressor. We show that, depending on the geometrical properties of the WG, the exiting beam consists of a defined number of wavelengths which can be shifted by changing the angle of incidence of the white x-ray synchrotron beam. The characteristic far-field pattern is recorded as a function of exit angle and energy. This x-ray optical setup may be used to enhance the intensity of coherent x-ray WG beams since the full energetic acceptance of the WG mode is transmitted.

  8. Solar x ray astronomy rocket program

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The dynamics were studied of the solar corona through the imaging of large scale coronal structures with AS&E High Resolution Soft X ray Imaging Solar Sounding Rocket Payload. The proposal for this program outlined a plan of research based on the construction of a high sensitivity X ray telescope from the optical and electronic components of the previous flight of this payload (36.038CS). Specifically, the X ray sensitive CCD camera was to be placed in the prime focus of the grazing incidence X ray mirror. The improved quantum efficiency of the CCD detector (over the film which had previously been used) allows quantitative measurements of temperature and emission measure in regions of low x ray emission such as helmet streamers beyond 1.2 solar radii or coronal holes. Furthermore, the improved sensitivity of the CCD allows short exposures of bright objects to study unexplored temporal regimes of active region loop evolution.

  9. Handbook Of X-ray Astronomy

    NASA Astrophysics Data System (ADS)

    Arnaud, Keith A.; Smith, R. K.; Siemiginowska, A.; Edgar, R. J.; Grant, C. E.; Kuntz, K. D.; Schwartz, D. A.

    2011-09-01

    This poster advertises a book to be published in September 2011 by Cambridge University Press. Written for graduate students, professional astronomers and researchers who want to start working in this field, this book is a practical guide to x-ray astronomy. The handbook begins with x-ray optics, basic detector physics and CCDs, before focussing on data analysis. It introduces the reduction and calibration of x-ray data, scientific analysis, archives, statistical issues and the particular problems of highly extended sources. The book describes the main hardware used in x-ray astronomy, emphasizing the implications for data analysis. The concepts behind common x-ray astronomy data analysis software are explained. The appendices present reference material often required during data analysis.

  10. X-ray diffraction: instrumentation and applications.

    PubMed

    Bunaciu, Andrei A; Udriştioiu, Elena Gabriela; Aboul-Enein, Hassan Y

    2015-01-01

    X-ray diffraction (XRD) is a powerful nondestructive technique for characterizing crystalline materials. It provides information on structures, phases, preferred crystal orientations (texture), and other structural parameters, such as average grain size, crystallinity, strain, and crystal defects. X-ray diffraction peaks are produced by constructive interference of a monochromatic beam of X-rays scattered at specific angles from each set of lattice planes in a sample. The peak intensities are determined by the distribution of atoms within the lattice. Consequently, the X-ray diffraction pattern is the fingerprint of periodic atomic arrangements in a given material. This review summarizes the scientific trends associated with the rapid development of the technique of X-ray diffraction over the past five years pertaining to the fields of pharmaceuticals, forensic science, geological applications, microelectronics, and glass manufacturing, as well as in corrosion analysis.

  11. Apollo 15 X-ray fluorescence experiment

    NASA Technical Reports Server (NTRS)

    Adler, I.; Trombka, J.; Gerard, J.; Schmadebeck, R.; Lowman, P.; Blodgett, H.; Yin, L.; Eller, E.; Lamothe, R.; Gorenstein, P.

    1971-01-01

    The X-ray fluorescence spectrometer, carried in the SIM bay of the command service module was employed principally for compositional mapping of the lunar surface while in lunar orbit, and secondarily, for X-ray astronomical observations during the trans-earth coast. The lunar surface measurements involved observations of the intensity and characteristics energy distribution of the secondary or fluorescent X-rays produced by the interaction of solar X-rays with the lunar surface. The astronomical observations consisted of relatively long periods of measurements of X-rays from pre-selected galactic sources such as Cyg-X-1 and Sco X-1 as well as from the galactic poles.

  12. X-rays from hot subdwarfs

    NASA Astrophysics Data System (ADS)

    Mereghetti, Sandro; La Palombara, Nicola

    2016-09-01

    Thanks to the high sensitivity of the instruments on board the XMM-Newton and Chandra satellites, it has become possible to explore the properties of the X-ray emission from hot subdwarfs. The small but growing sample of hot subdwarfs detected in X-rays includes binary systems, in which the X-rays result from wind accretion onto a compact companion (white dwarf or neutron star), as well as isolated sdO stars in which X-rays are probably due to shock instabilities in the wind. X-ray observations of these low mass stars provide information which can be useful also for our understanding of the winds of more luminous and massive early-type stars and can lead to the discovery of particularly interesting binary systems.

  13. X-Rays from Green Pea Analogs

    NASA Astrophysics Data System (ADS)

    Brorby, Matthew

    2014-09-01

    X-rays may have contributed to the heating and reionization of the IGM in the early universe. High mass X-ray binaries (HMXB) within small, low-metallicity galaxies are expected to be the main source of X-rays at this time. Since studying these high-redshift galaxies is currently impossible, we turn to local analogs that have the same properties the galaxies in the early are expected to have. A number of recent studies have shown an enhanced number of HMXBs in nearby low metallicity galaxies. We propose to observe a sample of metal-deficient luminous compact galaxies (LCG) in order to determine if the X-ray luminosity is enhanced relative to SFR, thereby providing further evidence to the importance of X-rays in the early universe.

  14. Removal of iodide from water by chlorination and subsequent adsorption on powdered activated carbon.

    PubMed

    Ikari, Mariya; Matsui, Yoshihiko; Suzuki, Yuta; Matsushita, Taku; Shirasaki, Nobutaka

    2015-01-01

    Chlorine oxidation followed by treatment with activated carbon was studied as a possible method for removing radioactive iodine from water. Chlorination time, chlorine dose, the presence of natural organic matter (NOM), the presence of bromide ion (Br⁻), and carbon particle size strongly affected iodine removal. Treatment with superfine powdered activated carbon (SPAC) after 10-min oxidation with chlorine (1 mg-Cl₂/L) removed 90% of the iodine in NOM-containing water (dissolved organic carbon concentration, 1.5 mg-C/L). Iodine removal in NOM-containing water increased with increasing chlorine dose up to 0.1 mg-Cl₂/L but decreased at chlorine doses of >1.0 mg-Cl₂/L. At a low chlorine dose, nonadsorbable iodide ion (I⁻) was oxidized to adsorbable hypoiodous acid (HOI). When the chlorine dose was increased, some of the HOI reacted with NOM to form adsorbable organic iodine (organic-I). Increasing the chlorine dose further did not enhance iodine removal, owing to the formation of nonadsorbable iodate ion (IO₃⁻). Co-existing Br⁻ depressed iodine removal, particularly in NOM-free water, because hypobromous acid (HOBr) formed and catalyzed the oxidation of HOI to IO₃⁻. However, the effect of Br⁻ was small in the NOM-containing water because organic-I formed instead of IO₃⁻. SPAC (median particle diameter, 0.62 μm) had a higher equilibrium adsorption capacity for organic-I than did conventional PAC (median diameter, 18.9 μm), but the capacities of PAC and SPAC for HOI were similar. The reason for the higher equilibrium adsorption capacity for organic-I was that organic-I was adsorbed principally on the exterior of the PAC particles and not inside the PAC particles, as indicated by direct visualization of the solid-phase iodine concentration profiles in PAC particles by field emission electron probe microanalysis. In contrast, HOI was adsorbed evenly throughout the entire PAC particle. PMID:25462731

  15. Quantitative Measurements of X-ray Intensity

    SciTech Connect

    Haugh, M. J., Schneider, M.

    2011-09-01

    This chapter describes the characterization of several X-ray sources and their use in calibrating different types of X-ray cameras at National Security Technologies, LLC (NSTec). The cameras are employed in experimental plasma studies at Lawrence Livermore National Laboratory (LLNL), including the National Ignition Facility (NIF). The sources provide X-rays in the energy range from several hundred eV to 110 keV. The key to this effort is measuring the X-ray beam intensity accurately and traceable to international standards. This is accomplished using photodiodes of several types that are calibrated using radioactive sources and a synchrotron source using methods and materials that are traceable to the U.S. National Institute of Standards and Technology (NIST). The accreditation procedures are described. The chapter begins with an introduction to the fundamental concepts of X-ray physics. The types of X-ray sources that are used for device calibration are described. The next section describes the photodiode types that are used for measuring X-ray intensity: power measuring photodiodes, energy dispersive photodiodes, and cameras comprising photodiodes as pixel elements. Following their description, the methods used to calibrate the primary detectors, the power measuring photodiodes and the energy dispersive photodiodes, as well as the method used to get traceability to international standards are described. The X-ray source beams can then be measured using the primary detectors. The final section then describes the use of the calibrated X-ray beams to calibrate X-ray cameras. Many of the references are web sites that provide databases, explanations of the data and how it was generated, and data calculations for specific cases. Several general reference books related to the major topics are included. Papers expanding some subjects are cited.

  16. Detection of x ray sources in PROS

    NASA Technical Reports Server (NTRS)

    Deponte, J.; Primini, F. A.

    1992-01-01

    The problem of detecting discrete sources in x-ray images has much in common with the problem of automatic source detection at other wavelengths. In all cases, one searches for positive brightness enhancements exceeding a certain threshold, which appear consistent with what one expects for a point source, in the presence of a (possibly) spatially variable background. Multidimensional point spread functions (e.g., dependent on detector position and photon energy) are also common. At the same time, the problem in x-ray astronomy has some unique aspects. For example, for typical x-ray exposures in current or recent observatories, the number of available pixels far exceeds the number of actual x-ray events, so Poisson, rather than Gaussian statistics apply. Further, extended cosmic x-ray sources are common, and one often desires to detect point sources in the vicinity or even within bright, diffuse x-ray emission. Finally, support structures in x-ray detectors often cast sharp shadows in x-ray images making it necessary to detect sources in a region of rapidly varying exposure. We have developed a source detection package within the IRAF/PROS environment which attempts to deal with some of the problems of x-ray source detection. We have patterned our package after the successful Einstein Observatory x-ray source detection programs. However, we have attempted to improve the flexibility and accessibility of the functions and to provide a graphical front-end for the user. Our philosophy has been to use standard IRAF tasks whenever possible for image manipulation and to separate general functions from mission-specific ones. We will report on the current status of the package and discuss future developments, including simulation tasks, to allow the user to assess detection efficiency and source significance, tasks to determine source intensity, and alternative detection algorithms.

  17. Performance Characteristics of Waste Glass Powder Substituting Portland Cement in Mortar Mixtures

    NASA Astrophysics Data System (ADS)

    Kara, P.; Csetényi, L. J.; Borosnyói, A.

    2016-04-01

    In the present work, soda-lime glass cullet (flint, amber, green) and special glass cullet (soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp cullet and incandescent light bulb borosilicate glass waste cullet) were ground into fine powders in a laboratory planetary ball mill for 30 minutes. CEM I 42.5N Portland cement was applied in mortar mixtures, substituted with waste glass powder at levels of 20% and 30%. Characterisation and testing of waste glass powders included fineness by laser diffraction particle size analysis, specific surface area by nitrogen adsorption technique, particle density by pycnometry and chemical analysis by X-ray fluorescence spectrophotometry. Compressive strength, early age shrinkage cracking and drying shrinkage tests, heat of hydration of mortars, temperature of hydration, X-ray diffraction analysis and volume stability tests were performed to observe the influence of waste glass powder substitution for Portland cement on physical and engineering properties of mortar mixtures.

  18. Determination of the Sensibility Factors for TLD-100 Powder on the Energy of X-Ray of 50, 250 kVp; 192Ir, 137Cs and 60Co

    SciTech Connect

    Loaiza, Sandra P.; Alvarez, Jose T.

    2006-09-08

    TLD-100 powder is calibrated in terms of absorbed dose to water Dw, using the protocols AAPM TG61, AAPM TG43 and IAEA-TRS 398, for the energy of RX 50, 250 kVp, 137Cs and 60Co respectively. The calibration curves, TLD Response R versus Dw, are fitted by weighted least square by a quadratic polynomials; which are validated with the lack of fit and the Anderson-Darling normality test. The slope of these curves corresponds to the sensibility factor: Fs R/DW, [Fs] = nC Gy-1. The expanded uncertainties U's for these factors are obtained from the ANOVA tables. Later, the Fs' values are interpolated using the effective energy hvefec for the 192Ir. The SSDL sent a set of capsules with powder TLD-100 for two Hospitals. These irradiated them a nominal dose of Dw = 2 Gy. The results determined at SSDL are: for the Hospital A the Dw is overestimated in order to 4.8% and the Hospital B underestimates it in the range from -1.4% to -17.5%.

  19. Optical and x-ray photoelectron spectroscopy studies of α-Al2O3

    NASA Astrophysics Data System (ADS)

    Prakash, Ram; Kumar, Sandeep; Kumar, Vinay; Choudhary, R. J.; Phase, D. M.

    2016-05-01

    α-Al2O3 powder sample was synthesized at 550 °C via solution combustion synthesis (SCS) method using urea as an organic fuel. The sample was characterized by X-ray diffraction (XRD), Optical spectroscopy and X-ray photoelectron spectroscopy (XPS) without any further thermal treatment. XRD study reveals that the powder crystallized directly in the hexagons α-Al2O3 phase. A band gap of 5.7 eV was estimated using diffuse reflectance spectra. For surface investigation X-ray photo electron spectroscopy (XPS) was carried out. The XPS survey scan study of α-Al2O3 powder reveals that the sample is free from impurity. The core levels of Al-2s and O-1s are also reported.

  20. Recent X-ray Variability of Eta Car Approaching The X-ray Eclipse

    NASA Technical Reports Server (NTRS)

    Corcoran, M.; Swank, J. H.; Ishibashi, K.; Gull, T.; Humphreys, R.; Damineli, A.; Walborn, N.; Hillier, D. J.; Davidson, K.; White, S. M.

    2002-01-01

    We discuss recent X-ray spectral variability of the supermassive star Eta Car in the interval since the last X-ray eclipse in 1998. We concentrate on the interval just prior to the next X-ray eclipse which is expected to occur in June 2003. We compare the X-ray behavior during the 2001-2003 cycle with the previous cycle (1996-1998) and note similarities and differences in the temporal X-ray behavior. We also compare a recent X-ray observation of Eta Car obtained with the Chandra high energy transmission grating in October 2002 with an earlier observation from Nov 2002, and interpret these results in terms of the proposed colliding wind binary model for the star. In addition we discuss planned observations for the upcoming X-ray eclipse.

  1. Selection of patients for x-ray examinations: Chest x-ray screening examinations

    SciTech Connect

    Not Available

    1983-08-01

    Five chest x-ray referral criteria statements have been developed and unanimously endorsed by a panel of physicians convened as part of a major voluntary cooperative effort between FDA's National Center for Devices and Radiological Health (NCDRH) and the medical professional community. The referral criteria statements include recommendations concerning the following applications of chest x-ray screening: mandated routine chest x-ray screening examinations, routine prenatal chest x-ray examinations, routine hospital admission chest x-ray examinations, chest x-ray examinations for tuberculosis detection and control, and routine chest x-ray examinations for occupational medicine. The complete text of the five referral criterial statements plus a brief discussion of the rationale for the development of each statement is presented.

  2. Observation of living cells by x-ray microscopy with a laser-plasma x-ray source

    NASA Astrophysics Data System (ADS)

    Tomie, Toshihisa; Shimizu, Hazime; Majima, Toshikazu; Yamada, Mitsuo; Kanayama, Toshihiko; Yano, M.; Kondo, H.

    1991-12-01

    We studied laser-produced plasma as an x-ray source for x-ray microscopy. Using water- window x rays, contact x-ray images of living sea urchin sperm were taken by a 500 picosecond x-ray pulse. The resist relief was examined by atomic force microscope and informations characteristic of x-ray microscopy were obtained. The finest feature noticed in the x-ray image was 0.1 micrometers .

  3. Design and characterization of a pulsed x-ray source for fluorescent lifetime measurements

    SciTech Connect

    Blankespoor, S.C. |

    1993-12-01

    To search for new, fast, inorganic scintillators, the author and his colleagues have developed a bench-top pulsed x-ray source for determining fluorescent lifetimes and wavelengths of compounds in crystal or powdered form. This source uses a light-excited x-ray tube which produces x-rays when light from a laser diode strikes its photocathode. The x-ray tube has a tungsten anode, a beryllium exit window, a 30 kV maximum tube bias, and a 50 HA maximum average cathode current. The laser produces 3 {times} 10{sup 7} photons at 650 nm per {approximately}100 ps pulse, with up to 10{sup 7} pulses/sec. The time spread for the laser diode, x-ray tube, and a microchannel plate photomultiplier tube is less than 120 ps fwhm. The mean x-ray photon energy, at tube biases of 20, 25, and 30 kV, is 9.4, 10.3, and 11.1 keV, respectively. They measured 140, 230, and 330 x-ray photons per laser diode pulse per steradian at tube biases of 20, 25, and 30 kV, respectively. Background x-rays due to dark current occur at a rate of 1 {times} 10{sup 6} and 3 {times} 10{sup 6} photons/sec/steradian at tube biases of 25 and 30 kV, respectively. Data characterizing the x-ray output with an aluminum filter in the x-ray beam are also presented.

  4. Toward active x-ray telescopes

    NASA Astrophysics Data System (ADS)

    O'Dell, Stephen L.; Atkins, Carolyn; Button, Timothy W.; Cotroneo, Vincenzo; Davis, William N.; Doel, Peter; Feldman, Charlotte H.; Freeman, Mark D.; Gubarev, Mikhail V.; Kolodziejczak, Jeffery J.; Michette, Alan G.; Ramsey, Brian D.; Reid, Paul B.; Rodriguez Sanmartin, Daniel; Saha, Timo T.; Schwartz, Daniel A.; Trolier-McKinstry, Susan; Wilke, Rudeger H. T.; Willingale, Richard; Zhang, William W.

    2011-09-01

    Future x-ray observatories will require high-resolution (< 1") optics with very-large-aperture (> 25 m2) areas. Even with the next generation of heavy-lift launch vehicles, launch-mass constraints and aperture-area requirements will limit the areal density of the grazing-incidence mirrors to about 1 kg/m2 or less. Achieving sub-arcsecond x-ray imaging with such lightweight mirrors will require excellent mirror surfaces, precise and stable alignment, and exceptional stiffness or deformation compensation. Attaining and maintaining alignment and figure control will likely involve active (in-space adjustable) x-ray optics. In contrast with infrared and visible astronomy, active optics for x-ray astronomy is in its infancy. In the middle of the past decade, two efforts began to advance technologies for adaptive x-ray telescopes: The Smart X-ray Optics (SXO) Basic Technology project in the United Kingdom (UK) and the Generation-X (Gen-X) concept studies in the United States (US). This paper discusses relevant technological issues and summarizes progress toward active x-ray telescopes.

  5. Toward Active X-ray Telescopes II

    NASA Technical Reports Server (NTRS)

    O'Dell, Stephen L.; Aldroft, Thomas L.; Atkins, Carolyn; Button, Timothy W.; Cotroneo, Vincenzo; Davis, William N.; Doel, Peter; Feldman, Charlotte H.; Freeman, Mark D.; Gubarev, Mikhail V.; Johnson-Wilke, Raegan L.; Kolodziejczak, Jeffery J.; Lillie, Charles F.; Michette, Alan G.; Ramsey, Brian D.; Reid, Paul B.; Sanmartin, Daniel Rodriguez; Saha, Timo T.; Schwartz, Daniel A.; Trolier-McKinstry, Susan E.; Ulmer, Melville P.; Wilke, Rudeger H. T.; Willingale, Richard; Zhang, William W.

    2012-01-01

    In the half century since the initial discovery of an astronomical (non-solar) x-ray source, the sensitivity for detection of cosmic x-ray sources has improved by ten orders of magnitude. Largely responsible for this dramatic progress has been the refinement of the (grazing-incidence) focusing x-ray telescope. The future of x-ray astronomy relies upon the development of x-ray telescopes with larger aperture areas (greater than 1 m2) and finer angular resolution (less than 1.). Combined with the special requirements of grazing-incidence optics, the mass and envelope constraints of space-borne telescopes render such advances technologically challenging.requiring precision fabrication, alignment, and assembly of large areas (greater than 100 m2) of lightweight (approximately 1 kg m2 areal density) mirrors. Achieving precise and stable alignment and figure control may entail active (in-space adjustable) x-ray optics. This paper discusses relevant programmatic and technological issues and summarizes progress toward active x-ray telescopes.

  6. Toward Adaptive X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    O'Dell, Stephen L.; Atkins, Carolyn; Button, Tim W.; Cotroneo, Vincenzo; Davis, William N.; Doel, Peer; Feldman, Charlotte H.; Freeman, Mark D.; Gubarev, Mikhail V.; Kolodziejczak, Jeffrey J.; Michette, Alan G.; Ramsey, Brian D.; Reid, Paul B.; Rodriguez Sanmartin, Daniel; Saha, Timo T.; Schwartz, Daniel A.; Trolier-McKinstry, Susan; Wilke, Rudeger H. T.; Willingale, Richard; Zhang, William W.

    2011-01-01

    Future x-ray observatories will require high-resolution (less than 1 inch) optics with very-large-aperture (greater than 25 square meter) areas. Even with the next generation of heavy-lift launch vehicles, launch-mass constraints and aperture-area requirements will limit the surface areal density of the grazing-incidence mirrors to about 1 kilogram per square meter or less. Achieving sub-arcsecond x-ray imaging with such lightweight mirrors will require excellent mirror surfaces, precise and stable alignment, and exceptional stiffness or deformation compensation. Attaining and maintaining alignment and figure control will likely involve adaptive (in-space adjustable) x-ray optics. In contrast with infrared and visible astronomy, adaptive optics for x-ray astronomy is in its infancy. In the middle of the past decade, two efforts began to advance technologies for adaptive x-ray telescopes: The Generation-X (Gen-X) concept studies in the United States, and the Smart X-ray Optics (SXO) Basic Technology project in the United Kingdom. This paper discusses relevant technological issues and summarizes progress toward adaptive x-ray telescopes.

  7. X-ray monitoring for astrophysical applications

    NASA Astrophysics Data System (ADS)

    Pina, L.; Burrows, D.; Cash, W.; Cerna, D.; Gorenstein, P.; Hudec, R.; Inneman, A.; Jakubek, J.; Marsikova, V.; Sieger, L.; Tichy, V.

    2014-09-01

    This work addresses the issue of X-ray monitoring for astrophysical applications. The proposed wide-field optical system has not been used in space yet. The proposed novel approach is based on the use of 1D "Lobster eye" optics in combination with Timepix X-ray detector in the energy range 3 - 40 keV. The proposed project includes theoretical study and a functional sample of the Timepix X-ray detector with multifoil wide-field X-ray "Lobster eye" optics. Using optics to focus X-rays on a detector is the only solution in cases the intensity of impinging X-ray radiation is below the sensitivity of the detector, e.g. while monitoring astrophysical objects in space, or phenomena in the Earth's atmosphere. The optical system could be used in a student rocket experiment at University of Colorado. Ideal opportunity is to extend the CubeSat of Pennsylvania State University with the hard X-ray telescope demonstrator consisting of an optical module and Timepix detector.

  8. GEMS X-ray Polarimeter Performance Simulations

    NASA Technical Reports Server (NTRS)

    Baumgartner, Wayne H.; Strohmayer, Tod; Kallman, Tim; Black, J. Kevin; Hill, Joanne; Swank, Jean

    2012-01-01

    The Gravity and Extreme Magnetism Small explorer (GEMS) is an X-ray polarization telescope selected as a NASA small explorer satellite mission. The X-ray Polarimeter on GEMS uses a Time Projection Chamber gas proportional counter to measure the polarization of astrophysical X-rays in the 2-10 keV band by sensing the direction of the track of the primary photoelectron excited by the incident X-ray. We have simulated the expected sensitivity of the polarimeter to polarized X-rays. We use the simulation package Penelope to model the physics of the interaction of the initial photoelectron with the detector gas and to determine the distribution of charge deposited in the detector volume. We then model the charge diffusion in the detector,and produce simulated track images. Within the track reconstruction algorithm we apply cuts on the track shape and focus on the initial photoelectron direction in order to maximize the overall sensitivity of the instrument, using this technique we have predicted instrument modulation factors nu(sub 100) for 100% polarized X-rays ranging from 10% to over 60% across the 2-10 keV X-ray band. We also discuss the simulation program used to develop and model some of the algorithms used for triggering, and energy measurement of events in the polarimeter.

  9. Surface Reactivity of Iron Oxide Pigmentary Powders toward Atmospheric Components: XPS and Gravimetry of Oxygen and Water Vapor Adsorption

    PubMed

    Ismail; Cadenhead; Zaki

    1996-11-10

    The adsorption of oxygen and water vapor on a number of specially prepared alpha-Fe2O3 samples was measured gravimetrically at 25°C. The samples themselves were prepared from a steel-pickling chemical waste (97 wt% FeSO4·7H2O) by roasting the original material at 700°C for 5 h in air, oxygen, and nitrogen. Estimated surface coverages by the adsorbed oxygen and water vapor were made on the basis of nitrogen-adsorption-based surface areas, while the nature of the sample surfaces was investigated by both X-ray photoelectron spectroscopy (XPS) and field emission SEM (FESEM) techniques. In addition a depth profiling study utilizing a sputtering argon beam and XPS was undertaken. Morphological studies using FESEM showed that, while the surface areas were essentially the same (27-29 m2/g) for all three samples, the sample prepared in nitrogen had a significantly larger particle size than the other two. These studies also indicated that neither oxygen nor water vapor adsorption caused any significant structural changes. The differing sample preparations resulted in differing oxygenated surfaces for the alpha-Fe2O3 samples, with the degree of oxygenation decreasing in the order of preparatory gases: oxygen, (wet) air, nitrogen. The amounts of both oxygen and water vapor adsorbed were in inverse proportion to the original degree of surface oxygenation, though the amounts of both represented fractional coverage at best. While the water vapor adsorption was always greater than that of oxygen, the former was more weakly adsorbed, as was indicated by the ease of desorption. Depth profiling failed to indicate any bulk diffusion of oxygen but could not be considered reliable since even the attenuated argon beam used here still brought about reduction of surface iron. Both oxygen and dissociative water adsorption are thought to involve surface sites of high coordination unsaturation. Oxygen is postulated to adsorb on such poorly oxygenated sites primarily as O-2; however, O2

  10. Globular cluster x-ray sources.

    PubMed

    Pooley, David

    2010-04-20

    Globular clusters and x-ray astronomy have a long and fruitful history. Uhuru and OSO-7 revealed highly luminous (> 10(36) ergs(-1)) x-ray sources in globular clusters, and Einstein and ROSAT revealed a larger population of low-luminosity (< 10(33) ergs(-1)) x-ray sources. It was realized early on that the high-luminosity sources were low-mass x-ray binaries in outburst and that they were orders of magnitude more abundant per unit mass in globular clusters than in the rest of the galaxy. However, the low-luminosity sources proved difficult to classify. Many ideas were put forth--low-mass x-ray binaries in quiescence (qLMXBs), cataclysmic variables (CVs), active main-sequence binaries (ABs), and millisecond pulsars (MSPs)--but secure identifications were scarce. In ROSAT observations of 55 clusters, about 25 low-luminosity sources were found. Chandra has now observed over 80 Galactic globular clusters, and these observations have revealed over 1,500 x-ray sources. The superb angular resolution has allowed for many counterpart identifications, providing clues to the nature of this population. It is a heterogeneous mix of qLMXBs, CVs, ABs, and MSPs, and it has been shown that the qLMXBs and CVs are both, in part, overabundant like the luminous LMXBs. The number of x-ray sources in a cluster correlates very well with its encounter frequency. This points to dynamical formation scenarios for the x-ray sources and shows them to be excellent tracers of the complicated internal dynamics. The relation between the encounter frequency and the number of x-ray sources has been used to suggest that we have misunderstood the dynamical states of globular clusters.

  11. Quasar x-ray spectra revisited

    NASA Technical Reports Server (NTRS)

    Shastri, P.; Wilkes, B. J.; Elvis, M.; Mcdowell, J.

    1992-01-01

    A sample of 45 quasars observed by the Imaging Proportional Counter (IPC) on the Einstein satellite is used to re-examine the relationship between the soft (0.2-3.5 keV) X-ray energy index and radio-loudness. We found the following: (1) the tendency for radio-loud quasars to have systematically flatter X-ray slopes than radio-quiet quasars (RQQ's) is confirmed with the soft X-ray excess having negligible effect; (2) there is a tendency for the flatness of the X-ray slope to correlate with radio core-dominance for radio-loud quasars, suggesting that a component of the X-ray emission is relativistically beamed; (3) for the RQQ's the soft X-ray slopes, with a mean of approximately 1.0, are consistent with the slopes found at higher energies (2-10 keV) although steeper than those observed for Seyfert 1 galaxies (also 2-10 keV) where the reflection model gives a good fit to the data; (4) the correlation of FeII emission line strength with X-ray energy index is confirmed for radio-quiet quasars using a subset of 18 quasars. The radio-loud quasars show no evidence for a correlation. This relation suggests a connection between the ionizing continuum and the line emission from the broad emission line region (BELR) of radio-quiet quasars, but in the opposite sense to that predicted by current photoionization models; and (5) the correlations of X-ray slope with radio core dominance and FeII equivalent width within the radio-loud and radio-quiet sub-classes respectively imply that the observed wide range of X-ray spectral slopes is real rather than due to the large measuring uncertainties for individual objects.

  12. Globular cluster x-ray sources

    PubMed Central

    Pooley, David

    2010-01-01

    Globular clusters and x-ray astronomy have a long and fruitful history. Uhuru and OSO-7 revealed highly luminous (> 1036 ergs-1) x-ray sources in globular clusters, and Einstein and ROSAT revealed a larger population of low-luminosity (< 1033 ergs-1) x-ray sources. It was realized early on that the high-luminosity sources were low-mass x-ray binaries in outburst and that they were orders of magnitude more abundant per unit mass in globular clusters than in the rest of the galaxy. However, the low-luminosity sources proved difficult to classify. Many ideas were put forth—low-mass x-ray binaries in quiescence (qLMXBs), cataclysmic variables (CVs), active main-sequence binaries (ABs), and millisecond pulsars (MSPs)—but secure identifications were scarce. In ROSAT observations of 55 clusters, about 25 low-luminosity sources were found. Chandra has now observed over 80 Galactic globular clusters, and these observations have revealed over 1,500 x-ray sources. The superb angular resolution has allowed for many counterpart identifications, providing clues to the nature of this population. It is a heterogeneous mix of qLMXBs, CVs, ABs, and MSPs, and it has been shown that the qLMXBs and CVs are both, in part, overabundant like the luminous LMXBs. The number of x-ray sources in a cluster correlates very well with its encounter frequency. This points to dynamical formation scenarios for the x-ray sources and shows them to be excellent tracers of the complicated internal dynamics. The relation between the encounter frequency and the number of x-ray sources has been used to suggest that we have misunderstood the dynamical states of globular clusters. PMID:20404204

  13. X-ray in Zeta-Ori

    NASA Astrophysics Data System (ADS)

    López-García, M. A.; López-Santiago, J. L.; Albacete-Colombo, J. F.; De Castro, E.

    2013-05-01

    Nearby star-forming regions are ideal laboratories to study high-energy emission processes but they usually present high absorption what makes difficult to detect the stellar population inside the molecular complex. As young late-type stars show high X-ray emission and X-ray photons are little absorbed by interstellar material, X-ray dedicated surveys are an excellent tool to detect the low-mass stellar population in optically absorbed regions. In this work, we present a study of the star-forming region Zeta-Ori and its surroundings. We combine optical, infrared and X-ray data. Properties of the X-ray emiting plasma and infrared features of the young stellar objects detected in the XMM-Newton observation are determined. The southern part of the Orion B giant molecular cloud complex harbor other star forming regions, as NGC 2023 and NGC 2024, we use this regions to compare. We study the spectral energy distribution of X-ray sources. Combining these results with infrared, the X-ray sources are classified as class I, class II and class III objects. The X-ray spectrum and ligth curve of detected X-ray sources is analyzed to found flares. We use a extincion-independent index to select the stars with circumstellar disk, and study the relationship between the present of disk and the flare energy. The results are similar to others studies and we conclude that the coronal properties of class II and class III objects in this region do not differ significantly from each other and from stars of similar infrared class in the ONC.

  14. Imaging Cellular Architecture with X-rays

    PubMed Central

    Larabell, Carolyn A.; Nugent, Keith A.

    2012-01-01

    X-ray imaging of biological samples is progressing rapidly. In this paper we review the progress to date in high resolution imaging of cellular architecture. In particular we survey the progress in soft X-ray tomography and argue that the field is coming of age and that important biological insights are starting to emerge. We then review the new ideas based on coherent diffraction. These methods are at a much earlier stage of development but, as they eliminate the need for X-ray optics, have the capacity to provide substantially better spatial resolution than zone plate based methods. PMID:20869868

  15. The Future of X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.

    2013-01-01

    The most important next step is the development of X-ray optics comparable to (or better than) Chandra in angular resolution that far exceed Chandra s effective area. Use the long delay to establish an adequately funded, competitive technology program along the lines I have recommended. Don't be diverted from this objective, except for Explorer-class missions. Progress in X-ray optics, with emphasis on the angular resolution, is central to the paradigm-shifting discoveries and the contributions of X-ray astronomy to multiwavelength astrophysics over the past 51 years.

  16. X-ray microscopy using synchrotron radiation

    SciTech Connect

    Jones, K.W.; Gordon, B.M.; Hanson, A.L.; Pounds, J.G.; Rivers, M.L.; Schidlovsky, G.; Smith, J.V.; Spanne, P.; Sutton, S.R.

    1989-01-01

    The system for x-ray microscopy now being developed at the X-26 beam line of the Brookhaven National Synchrotron Light Source (NSLS) is described here. Examples of the use of x-ray microscopy for trace element geochemistry, biology and medicine, and materials investigations are given to emphasize the scientific applications of the technique. Future directions for the improvement and further development of the X-26 microscope and of the x-ray microscopy field in general are discussed. 11 refs., 7 figs.

  17. X-ray streak crystal spectography

    SciTech Connect

    Kauffman, R.L.; Brown, T.; Medecki, H.

    1983-07-01

    We have built an x-ray streaked crystal spectrograph for making time-resolved x-ray spectral measurements. This instrument can access Bragg angles from 11/sup 0/ to 38/sup 0/ and x-ray spectra from 200 eV to greater than 10 keV. We have demonstrated resolving powers, E/..delta..E > 200 at 1 keV and time resolution less than 20 psec. A description of the instrument and an example of the data is given.

  18. X-ray phase-contrast methods

    SciTech Connect

    Lider, V. V. Kovalchuk, M. V.

    2013-11-15

    This review is devoted to a comparative description of the methods for forming X-ray phase-contrast images of weakly absorbing (phase) objects. These include the crystal interferometer method, the Talbot interferometer method, diffraction-enhanced X-ray imaging, and the in-line method. The potential of their practical application in various fields of science and technology is discussed. The publications on the development and optimization of X-ray phase-contrast methods and the experimental study of phase objects are analyzed.

  19. Diffractive Imaging Using Partially Coherent X Rays

    NASA Astrophysics Data System (ADS)

    Whitehead, L. W.; Williams, G. J.; Quiney, H. M.; Vine, D. J.; Dilanian, R. A.; Flewett, S.; Nugent, K. A.; Peele, A. G.; Balaur, E.; McNulty, I.

    2009-12-01

    The measured spatial coherence characteristics of the illumination used in a diffractive imaging experiment are incorporated in an algorithm that reconstructs the complex transmission function of an object from experimental x-ray diffraction data using 1.4 keV x rays. Conventional coherent diffractive imaging, which assumes full spatial coherence, is a limiting case of our approach. Even in cases in which the deviation from full spatial coherence is small, we demonstrate a significant improvement in the quality of wave field reconstructions. Our formulation is applicable to x-ray and electron diffraction imaging techniques provided that the spatial coherence properties of the illumination are known or can be measured.

  20. New opportunities in X-ray tomography

    NASA Astrophysics Data System (ADS)

    Peele, A. G.; Quiney, H. M.; Dhal, B. B.; Mancuso, A. P.; Arhatari, B.; Nugent, K. A.

    2006-11-01

    We discuss standard X-ray-imaging techniques. Phase-imaging methods and a new class of nano-focus and nano-resolution laboratory systems offer new opportunities in true laboratory-based X-ray microtomography with a host of possible applications that have mainly been demonstrated only at synchrotron sources. Notwithstanding these advances, the diffraction limit for X-ray-imaging methods is a long way off. We preview the link between high-resolution 'standard' imaging schemes and the new field of coherent diffractive imaging.