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Sample records for aqueous solution x-ray

  1. Structure of MgSO4 in Concentrated Aqueous Solutions by X-Ray Diffraction

    Institute of Scientific and Technical Information of China (English)

    CAO Ling-di; FANG Yan; FANG Chun-hui

    2011-01-01

    Detailed time-and-space-averaged structure of MgSO4 in the concentrated aqueous solutions was investigated via X-ray diffraction with an X'pert Pro θ-θ diffractometer at 298 K, yielding structural function and radial distribution function(RDF). The developed KURVLR program was employed for the theoretical investigation in consideration of the ionic hydration and ion association. Multi-peaks Gaussian fitting method was applied to deconvolving the overlapping bands of Differential radial distribution function(DRDF). The calculation of the geometric model shows that octahedrally six-coordinated Mg(H2O)62+, with an Mg2+…Ow bond length of 0.201 nm dominates in the solutions. There exists contact ion-pair(CIP) in the more concentrated solution(1:18, H2O/salt molar ratio) with a coordination number of 0.8 and a characteristic Mg…S distance of 0.340 nm. The result indicates the hydrated SO42ion happens in the solution. The S…Ow bond distance was determined to be 0.382 nm with a coordination number of 13. The fraction of CIP increases significantly with the increasing concentration. The symmetry of the hydration structure of sulfate ion is lowered by forming complex with magnesium ion.

  2. Quantitative interpretation of molecular dynamics simulations for X-ray photoelectron spectroscopy of aqueous solutions

    Science.gov (United States)

    Olivieri, Giorgia; Parry, Krista M.; Powell, Cedric J.; Tobias, Douglas J.; Brown, Matthew A.

    2016-04-01

    Over the past decade, energy-dependent ambient pressure X-ray photoelectron spectroscopy (XPS) has emerged as a powerful analytical probe of the ion spatial distributions at the vapor (vacuum)-aqueous electrolyte interface. These experiments are often paired with complementary molecular dynamics (MD) simulations in an attempt to provide a complete description of the liquid interface. There is, however, no systematic protocol that permits a straightforward comparison of the two sets of results. XPS is an integrated technique that averages signals from multiple layers in a solution even at the lowest photoelectron kinetic energies routinely employed, whereas MD simulations provide a microscopic layer-by-layer description of the solution composition near the interface. Here, we use the National Institute of Standards and Technology database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to quantitatively interpret atom-density profiles from MD simulations for XPS signal intensities using sodium and potassium iodide solutions as examples. We show that electron inelastic mean free paths calculated from a semi-empirical formula depend strongly on solution composition, varying by up to 30% between pure water and concentrated NaI. The XPS signal thus arises from different information depths in different solutions for a fixed photoelectron kinetic energy. XPS signal intensities are calculated using SESSA as a function of photoelectron kinetic energy (probe depth) and compared with a widely employed ad hoc method. SESSA simulations illustrate the importance of accounting for elastic-scattering events at low photoelectron kinetic energies (hoc method systematically underestimates the preferential enhancement of anions over cations. Finally, some technical aspects of applying SESSA to liquid interfaces are discussed.

  3. Soft X-ray absorption spectra of aqueous salt solutions with highly charged cations in liquid microjets

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, Craig P.; Uejio, Janel S.; Duffin, Andrew M.; Drisdell, Walter S.; Smith, Jared D.; Saykally, Richard J.

    2010-03-11

    X-ray absorption spectra of 1M aqueous solutions of indium (III) chloride, yttrium (III) bromide, lanthanum (III) chloride, tin (IV) chloride and chromium (III) chloride have been measured at the oxygen K-edge. Relatively minor changes are observed in the spectra compared to that of pure water. SnCl{sub 4} and CrCl{sub 3} exhibit a new onset feature which is attributed to formation of hydroxide or other complex molecules in the solution. At higher energy, only relatively minor, but salt-specific changes in the spectra occur. The small magnitude of the observed spectral changes is ascribed to offsetting perturbations by the cations and anions.

  4. Practical guidelines for best practice on Total Reflection X-ray Fluorescence spectroscopy: Analysis of aqueous solutions

    Science.gov (United States)

    Riaño, Sofía; Regadío, Mercedes; Binnemans, Koen; Vander Hoogerstraete, Tom

    2016-10-01

    Despite the fact that Total Reflection X-ray Fluorescence (TXRF) is becoming more and more popular as a quantification technique in analytical chemistry due to its simplicity and robustness, there are still some key aspects related to the sample preparation that need to be improved. In this work, the effect of different parameters is investigated: measurement time, carrier position, sample volume and sample drying time. The measurement time and the sample volume on the carriers mainly affect the recovery rate and relative standard deviation of the quantified metal from aqueous solutions. The most important parameters that play a fundamental role in the calibration of a TXRF machine such as choice of the standard element and concentration ratio between the analyte and the standard are discussed. Practical and easy guidelines for the correct preparation of aqueous samples are presented. These can be used by both less and more experienced TXRF users, interested in measuring metal ion concentrations in aqueous samples.

  5. X-ray fluorescence-based method for the quantitative determination of uranium in the aqueous solutions

    Science.gov (United States)

    Dubrovka, S.; Chursin, S.; Verkhoturova, V.

    2017-01-01

    Currently, one of the important issues in the field of nuclear technology is providing special handling with respect to nuclear materials, due to their energy and commercial significancy, as well as their potential radiation contamination threat. There is a necessity to have information about the full qualitative and quantitative composition of the sample as a part of special handling with nuclear materials. Spectrometric methods solve this problem effectively. One of these methods is the X-ray fluorescence analysis, which is fast, nondestructive and environmentally friendly with a high accuracy and reproducibility of the results. Development of uranium quantitative determination method in aqueous solutions to solve the problems of accounting and control of nuclear materials is the subject of research in this article. The development of the uranium concentration determination method in the aqueous solutions of uranyl nitrate UO2(NO3)2 was carried out using Spectroscan MAKC-G – wavelength dispersive crystal diffraction XRF spectrometer.

  6. Nitrogen K-edge x-ray absorption near edge structure of pyrimidine-containing nucleotides in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Hiroyuki, E-mail: hshimada@cc.tuat.ac.jp; Minami, Hirotake; Okuizumi, Naoto; Sakuma, Ichiro; Ukai, Masatoshi [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei-shi, Tokyo 184-8588 (Japan); Fujii, Kentaro; Yokoya, Akinari [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Fukuda, Yoshihiro; Saitoh, Yuji [Synchrotron Radiation Research Center, Japan Atomic Energy Agency, Sayo-gun, Hyogo 679-5148 (Japan)

    2015-05-07

    X-ray absorption near edge structure (XANES) was measured at energies around the N K-edge of the pyrimidine-containing nucleotides, cytidine 5′-monophosphate (CMP), 2′-deoxythymidine 5′-monophosphate (dTMP), and uridine 5′-monophosphate (UMP), in aqueous solutions and in dried films under various pH conditions. The features of resonant excitations below the N K-edge in the XANES spectra for CMP, dTMP, and UMP changed depending on the pH of the solutions. The spectral change thus observed is systematically explained by the chemical shift of the core-levels of N atoms in the nucleobase moieties caused by structural changes due to protonation or deprotonation at different proton concentrations. This interpretation is supported by the results of theoretical calculations using density functional theory for the corresponding nucleobases in the neutral and protonated or deprotonated forms.

  7. Nitrogen K-edge x-ray absorption near edge structure of pyrimidine-containing nucleotides in aqueous solution.

    Science.gov (United States)

    Shimada, Hiroyuki; Minami, Hirotake; Okuizumi, Naoto; Sakuma, Ichiro; Ukai, Masatoshi; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro; Saitoh, Yuji

    2015-05-07

    X-ray absorption near edge structure (XANES) was measured at energies around the N K-edge of the pyrimidine-containing nucleotides, cytidine 5'-monophosphate (CMP), 2'-deoxythymidine 5'-monophosphate (dTMP), and uridine 5'-monophosphate (UMP), in aqueous solutions and in dried films under various pH conditions. The features of resonant excitations below the N K-edge in the XANES spectra for CMP, dTMP, and UMP changed depending on the pH of the solutions. The spectral change thus observed is systematically explained by the chemical shift of the core-levels of N atoms in the nucleobase moieties caused by structural changes due to protonation or deprotonation at different proton concentrations. This interpretation is supported by the results of theoretical calculations using density functional theory for the corresponding nucleobases in the neutral and protonated or deprotonated forms.

  8. X-ray absorption microscopy of aqueous samples

    Science.gov (United States)

    Frazer, Brad; Gilbert, Benjamin; De Stasio, Gelsomina

    2002-03-01

    X-ray photoelectron emission microscopy (X-PEEM) is used for numerous applications in surface microchemical analysis of material science and biological specimens. We have reconfigured the MEPHISTO X-PEEM instrument that is installed at the University of Wisconsin Synchrotron Radiation Center to measure true x-ray transmission spectra by converting transmitted photons to photoelectrons via a thin photocathode layer of gold. We have also developed a method by which to introduce aqueous samples into ultrahigh vacuum. Hence x-ray spectroscopy can be performed on biologically relevant elements (such as K, Ca, etc.) in a physiological environment, i.e., in solution. More important, when coupled with X-PEEM imaging this technique may offer the unique and exciting possibility of studying living cells. We present initial x-ray absorption spectra of solutions of aqueous ionic and chelated Ca, with the aim of distinguishing bound and free ionic calcium in vivo.

  9. Iron (III)-silica interactions in aqueous solution: insights from X.-ray absorption fine structure spectroscopy

    Science.gov (United States)

    Pokrovski, Gleb S.; Schott, Jacques; Farges, François; Hazemann, Jean-Louis

    2003-10-01

    The influence of aqueous silica on the hydrolysis of iron(III) nitrate and chloride salts in dilute aqueous solutions ( mFe ˜ 0.01 mol/kg) was studied at ambient temperature using X-ray absorption fine structure (XAFS) spectroscopy at the Fe K-edge. Results show that in Si-free iron nitrate and chloride solutions at acid pH (pH hydroxide complexes form via Fe-(O/OH)-Fe bonds. In these polymers, the first atomic shell of iron represents a distorted octahedron with six O/OH groups and Fe-O distances ranging from 1.92 to 2.07 Å. The Fe octahedra are linked together by their edges (Fe-Fe distance 2.92-3.12 Å) and corners (Fe-Fe distance ˜3.47 ± 0.03 Å). The Fe-Fe coordination numbers ( Nedge = 1-2; Ncorner = 0.5-0.7) are consistent with the dominant presence of iron dimers, trimers and tetramers at pH 2.5 to 2.9, and of higher-polymerized species at pH > 3. At pH > 2.5 in the presence of aqueous silica, important changes in Fe(III) hydrolysis are detected. In 0.05- m Si solutions (pH ˜ 2.7-3.0), the corner linkages between Fe octahedra in the polymeric complexes disappear, and the Fe-Fe distances corresponding to the edge linkages slightly increase (Fe-Fe edge ˜ 3.12-3.14 Å). The presence of 1 to 2 silicons at 3.18 ± 0.03 Å is detected in the second atomic shell around iron. At basic pH (˜12.7), similar structural changes are observed for the iron second shell. The Fe-Si and Fe-Fe distances and coordination numbers derived in this study are consistent with (1) Fe-Si complex stoichiometries Fe 2Si 1-2 and Fe 3Si 2-3 at pH silicon tetrahedra linked to two neighboring Fe octahedra via corners. At higher Si concentration (0.16 m, polymerized silica solution) and pH ˜ 3, the signal of the Fe second shell vanishes indicating the destruction of the Fe-Fe bonds and the formation of different Fe-Si linkages. Moreover, ˜20 mol.% of Fe is found to be tetrahedrally coordinated with oxygens in the first coordination shell ( RFe-O = 1.84 Å). This new finding implies

  10. Synchrotron-based in situ soft X-ray microscopy of Ag corrosion in aqueous chloride solution

    Science.gov (United States)

    Bozzini, B.; D'Urzo, L.; Gianoncelli, A.; Kaulich, B.; Kiskinova, M.; Prasciolu, M.; Tadjeddine, A.

    2009-09-01

    In this paper we report an in situ X-ray microscopy study of a model metal electrochemistry system, incorporating faradaic reactivity: the anodic corrosion and cathodic electrodeposition of Ag in aqueous systems. The information at sub-μm scale about morpho-chemical evolution of the electrified interface, provided by this novel electroanalytical approach fosters fundamental understanding of important issues concerning material fabrication and stability, which are crucial in developing the next generation electrochemical technologies, such as fuel cells and biosensors. The key methodology challenge faced in this pilot electrochemical experiments is combining a three-electrode configuration and wet environment, which required metal electrodes suitable for transmitting soft X-rays and a sealed cell allowing working in high vacuum. This has been solved via lithographic fabrication route fabricating 75 nm thick Ag electrodes and using Si3N4 membranes as X-ray windows and electrode support. Imaging in the STXM mode with phase contrast allowed us to monitor the corrosion morphologies and metal outgrowth features. Localised thickness variation and the build-up of reaction products of electron density different from that of the starting material have been detected with high sensitivity.

  11. Synchrotron-based in situ soft X-ray microscopy of Ag corrosion in aqueous chloride solution

    Energy Technology Data Exchange (ETDEWEB)

    Bozzini, B; D' Urzo, L [Dipartimento di Ingegneria dell' Innovazione, Universita del Salento, via Monteroni, 73100 Lecce (Italy); Gianoncelli, A; Kaulich, B; Kiskinova, M [Sincrotrone Trieste S.C.p.A., ELETTRA, s.s. 14 km 163.5 in Area Science Park, 34012 Basovizza, Trieste (Italy); Prasciolu, M [CNR-INFM TASC National Laboratory S.S.14 Km 163.5, Area Science Park, 34012 Basovizza, Trieste (Italy); Tadjeddine, A, E-mail: alessandra.gianoncelli@elettra.trieste.i [3UDIL/CNRS, BP34 91898 Orsay Cedex (France)

    2009-09-01

    In this paper we report an in situ X-ray microscopy study of a model metal electrochemistry system, incorporating faradaic reactivity: the anodic corrosion and cathodic electrodeposition of Ag in aqueous systems. The information at sub-{mu}m scale about morpho-chemical evolution of the electrified interface, provided by this novel electroanalytical approach fosters fundamental understanding of important issues concerning material fabrication and stability, which are crucial in developing the next generation electrochemical technologies, such as fuel cells and biosensors. The key methodology challenge faced in this pilot electrochemical experiments is combining a three-electrode configuration and wet environment, which required metal electrodes suitable for transmitting soft X-rays and a sealed cell allowing working in high vacuum. This has been solved via lithographic fabrication route fabricating 75 nm thick Ag electrodes and using Si{sub 3}N{sub 4} membranes as X-ray windows and electrode support. Imaging in the STXM mode with phase contrast allowed us to monitor the corrosion morphologies and metal outgrowth features. Localised thickness variation and the build-up of reaction products of electron density different from that of the starting material have been detected with high sensitivity.

  12. Ultraviolet photochemical reaction of [Fe(III)(C2O4)3](3-) in aqueous solutions studied by femtosecond time-resolved X-ray absorption spectroscopy using an X-ray free electron laser.

    Science.gov (United States)

    Ogi, Y; Obara, Y; Katayama, T; Suzuki, Y-I; Liu, S Y; Bartlett, N C-M; Kurahashi, N; Karashima, S; Togashi, T; Inubushi, Y; Ogawa, K; Owada, S; Rubešová, M; Yabashi, M; Misawa, K; Slavíček, P; Suzuki, T

    2015-05-01

    Time-resolved X-ray absorption spectroscopy was performed for aqueous ammonium iron(III) oxalate trihydrate solutions using an X-ray free electron laser and a synchronized ultraviolet laser. The spectral and time resolutions of the experiment were 1.3 eV and 200 fs, respectively. A femtosecond 268 nm pulse was employed to excite [Fe(III)(C2O4)3](3-) in solution from the high-spin ground electronic state to ligand-to-metal charge transfer state(s), and the subsequent dynamics were studied by observing the time-evolution of the X-ray absorption spectrum near the Fe K-edge. Upon 268 nm photoexcitation, the Fe K-edge underwent a red-shift by more than 4 eV within 140 fs; however, the magnitude of the redshift subsequently diminished within 3 ps. The Fe K-edge of the photoproduct remained lower in energy than that of [Fe(III)(C2O4)3](3-). The observed red-shift of the Fe K-edge and the spectral feature of the product indicate that Fe(III) is upon excitation immediately photoreduced to Fe(II), followed by ligand dissociation from Fe(II). Based on a comparison of the X-ray absorption spectra with density functional theory calculations, we propose that the dissociation proceeds in two steps, forming first [(CO2 (•))Fe(II)(C2O4)2](3-) and subsequently [Fe(II)(C2O4)2](2-).

  13. Ultraviolet photochemical reaction of [Fe(III(C2O43]3− in aqueous solutions studied by femtosecond time-resolved X-ray absorption spectroscopy using an X-ray free electron laser

    Directory of Open Access Journals (Sweden)

    Y. Ogi

    2015-05-01

    Full Text Available Time-resolved X-ray absorption spectroscopy was performed for aqueous ammonium iron(III oxalate trihydrate solutions using an X-ray free electron laser and a synchronized ultraviolet laser. The spectral and time resolutions of the experiment were 1.3 eV and 200 fs, respectively. A femtosecond 268 nm pulse was employed to excite [Fe(III(C2O43]3− in solution from the high-spin ground electronic state to ligand-to-metal charge transfer state(s, and the subsequent dynamics were studied by observing the time-evolution of the X-ray absorption spectrum near the Fe K-edge. Upon 268 nm photoexcitation, the Fe K-edge underwent a red-shift by more than 4 eV within 140 fs; however, the magnitude of the redshift subsequently diminished within 3 ps. The Fe K-edge of the photoproduct remained lower in energy than that of [Fe(III(C2O43]3−. The observed red-shift of the Fe K-edge and the spectral feature of the product indicate that Fe(III is upon excitation immediately photoreduced to Fe(II, followed by ligand dissociation from Fe(II. Based on a comparison of the X-ray absorption spectra with density functional theory calculations, we propose that the dissociation proceeds in two steps, forming first [(CO2•Fe(II(C2O42]3− and subsequently [Fe(II(C2O42]2−.

  14. In situ soft X-ray absorption spectroscopy investigation of electrochemical corrosion of copper in aqueous NaHCO3 solution

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Peng; Chen, Jeng-Lung; Borondics, Ferenc; Glans, Per-Anders; West, Mark W.; Chang, Ching-Lin; Salmeron, Miquel; Guo, Jinghua

    2010-03-31

    A novel electrochemical setup has been developed for soft x-ray absorption studies of the electronic structure of electrode materials during electrochemical cycling. In this communication we illustrate the operation of the cell with a study of the corrosion behavior of copper in aqueous NaHCO3 solution via the electrochemically induced changes of its electronic structure. This development opens the way for in situ investigations of electrochemical processes, photovoltaics, batteries, fuel cells, water splitting, corrosion, electrodeposition, and a variety of important biological processes.

  15. X-ray absorption spectroscopy of strontium(II) coordination. I. Static and thermal disorder in crystalline, hydrated, and precipitated solids and in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    O' Day, P.A.; Newville, M.; Neuhoff, P.S.; Sahai, N.; Carroll, S.A.

    2000-02-15

    Detailed analyses of crystalline, hydrated, and precipitated strontium compounds and an aqueous strontium solution by synchrotron extended X-ray adsorption fine structure (EXAFS) were used to quantify local thermal and static disorder and the characterize strontium coordination in a variety of oxygen-ligated bonding environments. Comparison of strontium structural coordination determined in this and previous studies suggest that previous EXAFS determinations of hydrated strontium may have underestimated first-shell interatomic distances and coordination numbers because minor contributions to the EXAFS phase-shift and amplitude functions were not accounted for, either theoretically or empirically.

  16. Nitrogen K-edge X-ray absorption near edge structure (XANES) spectra of purine-containing nucleotides in aqueous solution.

    Science.gov (United States)

    Shimada, Hiroyuki; Fukao, Taishi; Minami, Hirotake; Ukai, Masatoshi; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro; Saitoh, Yuji

    2014-08-07

    The N K-edge X-ray absorption near edge structure (XANES) spectra of the purine-containing nucleotide, guanosine 5'-monophosphate (GMP), in aqueous solution are measured under various pH conditions. The spectra show characteristic peaks, which originate from resonant excitations of N 1s electrons to π* orbitals inside the guanine moiety of GMP. The relative intensities of these peaks depend on the pH values of the solution. The pH dependence is explained by the core-level shift of N atoms at specific sites caused by protonation and deprotonation. The experimental spectra are compared with theoretical spectra calculated by using density functional theory for GMP and the other purine-containing nucleotides, adenosine 5'-monophosphate, and adenosine 5'-triphosphate. The N K-edge XANES spectra for all of these nucleotides are classified by the numbers of N atoms with particular chemical bonding characteristics in the purine moiety.

  17. An investigation into the subambient behavior of aqueous mannitol solutions using differential scanning calorimetry, cold stage microscopy, and X-ray diffractometry.

    Science.gov (United States)

    Kett, Vicky L; Fitzpatrick, Shaun; Cooper, Brett; Craig, Duncan Q M

    2003-09-01

    The subambient behavior of aqueous mannitol solutions is of considerable relevance to the preparation of freeze dried formulations. In this investigation the properties of 3% w/v mannitol solutions were investigated using differential scanning calorimetry (DSC), cold stage microscopy (CSM), and X-ray diffraction (XRD) to identify the thermal transitions and structural transformations undergone by this system. It was found that on cooling from ambient the system formed ice at circa -20 degrees C while a further exotherm was seen at approximately -30 degrees C. Upon reheating an endotherm was seen at circa -30 degrees C followed immediately by an exotherm at circa -25 degrees C. Temperature cycling indicated that the thermal transitions observed upon reheating were not reversible. Modulated temperature DSC (MTDSC) indicated that the transitions observed upon reheating corresponded to a glass transition immediately followed by recrystallization, XRD data showed that recrystallization was into the beta form. Annealing at -35 degrees C for 40 min prior to cooling and reheating resulted in a maximum enthalpy being observed for the reheating exotherm. It is concluded that on cooling 3% w/v aqueous mannitol solutions an amorphous phase is formed that subsequently recrystallises into the beta form. The study has also shown that DSC, CSM, and XRD are useful complementary techniques for the study of frozen systems.

  18. Competition between organics and bromide at the aqueous solution-air interface as seen from ozone uptake kinetics and X-ray photoelectron spectroscopy.

    Science.gov (United States)

    Lee, Ming-Tao; Brown, Matthew A; Kato, Shunsuke; Kleibert, Armin; Türler, Andreas; Ammann, Markus

    2015-05-14

    A more detailed understanding of the heterogeneous chemistry of halogenated species in the marine boundary layer is required. Here, we studied the reaction of ozone (O3) with NaBr solutions in the presence and absence of citric acid (C6H8O7) under ambient conditions. Citric acid is used as a proxy for oxidized organic material present at the ocean surface or in sea spray aerosol. On neat NaBr solutions, the observed kinetics is consistent with bulk reaction-limited uptake, and a second-order rate constant for the reaction of O3 + Br(-) is 57 ± 10 M(-1) s(-1). On mixed NaBr-citric acid aqueous solutions, the uptake kinetics was faster than that predicted by bulk reaction-limited uptake and also faster than expected based on an acid-catalyzed mechanism. X-ray photoelectron spectroscopy (XPS) on a liquid microjet of the same solutions at 1.0 × 10(-3)-1.0 × 10(-4) mbar was used to obtain quantitative insight into the interfacial composition relative to that of the bulk solutions. It revealed that the bromide anion becomes depleted by 30 ± 10% while the sodium cation gets enhanced by 40 ± 20% at the aqueous solution-air interface of a 0.12 M NaBr solution mixed with 2.5 M citric acid in the bulk, attributed to the role of citric acid as a weak surfactant. Therefore, the enhanced reactivity of bromide solutions observed in the presence of citric acid is not necessarily attributable to a surface reaction but could also result from an increased solubility of ozone at higher citric acid concentrations. Whether the acid-catalyzed chemistry may have a larger effect on the surface than in the bulk to offset the effect of bromide depletion also remains open.

  19. Effective interaction of charged platelets in aqueous solution: investigations of colloid laponite suspensions by static light scattering and small-angle x-ray scattering.

    Science.gov (United States)

    Li, Li; Harnau, L; Rosenfeldt, S; Ballauff, M

    2005-11-01

    We study dilute aqueous solutions of charged disklike mineral particles (laponite) by a combination of static light scattering (SLS) and small-angle x-ray scattering (SAXS). Laponite solutions are known to form gels above a certain critical concentration that must be described as nonequilibrium states. Here we focus on the investigation by SLS and SAXS at concentrations below gelation (cLaponite platelets as well as the structure factor describing their interaction at finite concentration. A detailed analysis of the combined sets of data proves that the solutions are in a well-defined equilibrium state. Moreover, this analysis demonstrates the internal consistency and accuracy of the scattering functions obtained at finite concentrations. We find that laponite particles interact through an effective pair potential that is attractive on short range but repulsive on longer range. This finding demonstrates that Laponite solutions exhibit only a limited stability at the concentration of added salt used herein. Raising the ionic strength to 0.005M already leads to slow flocculation as is evidenced from the enhanced scattering intensity at smallest scattering angles. All data strongly suggest that the gelation occurring at higher concentration is related to aggregation.

  20. EPR-Spin Trapping and Flow Cytometric Studies of Free Radicals Generated Using Cold Atmospheric Argon Plasma and X-Ray Irradiation in Aqueous Solutions and Intracellular Milieu.

    Directory of Open Access Journals (Sweden)

    Hidefumi Uchiyama

    Full Text Available Electron paramagnetic resonance (EPR-spin trapping and flow cytometry were used to identify free radicals generated using argon-cold atmospheric plasma (Ar-CAP in aqueous solutions and intracellularly in comparison with those generated by X-irradiation. Ar-CAP was generated using a high-voltage power supply unit with low-frequency excitation. The characteristics of Ar-CAP were estimated by vacuum UV absorption and emission spectra measurements. Hydroxyl (·OH radicals and hydrogen (H atoms in aqueous solutions were identified with the spin traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO, 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO, and phenyl N-t-butylnitrone (PBN. The occurrence of Ar-CAP-induced pyrolysis was evaluated using the spin trap 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS in aqueous solutions of DNA constituents, sodium acetate, and L-alanine. Human lymphoma U937 cells were used to study intracellular oxidative stress using five fluorescent probes with different affinities to a number of reactive species. The analysis and quantification of EPR spectra revealed the formation of enormous amounts of ·OH radicals using Ar-CAP compared with that by X-irradiation. Very small amounts of H atoms were detected whereas nitric oxide was not found. The formation of ·OH radicals depended on the type of rare gas used and the yield correlated inversely with ionization energy in the order of krypton > argon = neon > helium. No pyrolysis radicals were detected in aqueous solutions exposed to Ar-CAP. Intracellularly, ·OH, H2O2, which is the recombination product of ·OH, and OCl- were the most likely formed reactive oxygen species after exposure to Ar-CAP. Intracellularly, there was no practical evidence for the formation of NO whereas very small amounts of superoxides were formed. Despite the superiority of Ar-CAP in forming ·OH radicals, the exposure to X-rays proved more lethal. The mechanism of free radical formation in aqueous solutions and

  1. EPR-Spin Trapping and Flow Cytometric Studies of Free Radicals Generated Using Cold Atmospheric Argon Plasma and X-Ray Irradiation in Aqueous Solutions and Intracellular Milieu.

    Science.gov (United States)

    Uchiyama, Hidefumi; Zhao, Qing-Li; Hassan, Mariame Ali; Andocs, Gabor; Nojima, Nobuyuki; Takeda, Keigo; Ishikawa, Kenji; Hori, Masaru; Kondo, Takashi

    2015-01-01

    Electron paramagnetic resonance (EPR)-spin trapping and flow cytometry were used to identify free radicals generated using argon-cold atmospheric plasma (Ar-CAP) in aqueous solutions and intracellularly in comparison with those generated by X-irradiation. Ar-CAP was generated using a high-voltage power supply unit with low-frequency excitation. The characteristics of Ar-CAP were estimated by vacuum UV absorption and emission spectra measurements. Hydroxyl (·OH) radicals and hydrogen (H) atoms in aqueous solutions were identified with the spin traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO), 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO), and phenyl N-t-butylnitrone (PBN). The occurrence of Ar-CAP-induced pyrolysis was evaluated using the spin trap 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS) in aqueous solutions of DNA constituents, sodium acetate, and L-alanine. Human lymphoma U937 cells were used to study intracellular oxidative stress using five fluorescent probes with different affinities to a number of reactive species. The analysis and quantification of EPR spectra revealed the formation of enormous amounts of ·OH radicals using Ar-CAP compared with that by X-irradiation. Very small amounts of H atoms were detected whereas nitric oxide was not found. The formation of ·OH radicals depended on the type of rare gas used and the yield correlated inversely with ionization energy in the order of krypton > argon = neon > helium. No pyrolysis radicals were detected in aqueous solutions exposed to Ar-CAP. Intracellularly, ·OH, H2O2, which is the recombination product of ·OH, and OCl- were the most likely formed reactive oxygen species after exposure to Ar-CAP. Intracellularly, there was no practical evidence for the formation of NO whereas very small amounts of superoxides were formed. Despite the superiority of Ar-CAP in forming ·OH radicals, the exposure to X-rays proved more lethal. The mechanism of free radical formation in aqueous solutions and an

  2. Microfibrillar structure of PGG-glucan in aqueous solution as triple-helix aggregates by small angle x-ray scattering.

    Science.gov (United States)

    Gawronski, M; Park, J T; Magee, A S; Conrad, H

    1999-11-01

    The conformation of polysaccharide PGG-Glucan, isolated from yeast cell walls, in aqueous solution was investigated by small angle x-ray scattering (SAXS) and multidetector gel permeation chromatography coupled with postcolumn delivery (GPC/PCD) techniques in comparison with scleroglucan. It was shown that both polysaccharides exhibit a rigid rod-like conformation in aqueous solution by SAXS experiments. The mass per unit length (M/L) and radius (R) of rod cross section of PGG-Glucan were measured to be 6300 daltons/nm and 1.89 nm, while those of scleroglucan are 2300 and 0.83, respectively. Utilizing a GPC/light scattering technique, the average aggregation number of PGG-Glucan is 9, while that of scleroglucan is around 3. From the comparison of the M/L and R of the respective rod cross sections as well as their aggregation number data, it is concluded that PGG-Glucan is composed of triple helices, which tend to aggregate as triplets in solution, whereas scleroglucan is composed of a single triple helix. The aggregation number distribution of PGG-Glucan was found to range from 1 to about 25 determined by GPC/PCD. From the observation of a Debye-Scherrer ring type of peak in the macroscopic scattering cross section of PGG-Glucan by SAXS, the existence of a small amount of ordered clusters of PGG-Glucan can be deduced. The "lattice parameter" of these ordered fasces-like clusters is consistent with the radius of the individual triple-helical rods forming a microfibrillar superstructure. These results indicate that higher aggregated forms of PGG-Glucan containing up to 8 triple helices behave as ordered fasces-like clusters. We conclude that PGG-Glucan is triple-helix aggregates formed by rigid rods stacking together side by side. We propose a molecular structural model for PGG-Glucan conformations.

  3. Nitrogen K-edge X-ray absorption near edge structure (XANES) spectra of purine-containing nucleotides in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Hiroyuki; Fukao, Taishi; Minami, Hirotake; Ukai, Masatoshi [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei-shi, Tokyo 184-8588 (Japan); Fujii, Kentaro; Yokoya, Akinari [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Fukuda, Yoshihiro; Saitoh, Yuji [Synchrotron Radiation Research Center, Japan Atomic Energy Agency, Sayo-gun, Hyougo 679-5148 (Japan)

    2014-08-07

    The N K-edge X-ray absorption near edge structure (XANES) spectra of the purine-containing nucleotide, guanosine 5{sup ′}-monophosphate (GMP), in aqueous solution are measured under various pH conditions. The spectra show characteristic peaks, which originate from resonant excitations of N 1s electrons to π* orbitals inside the guanine moiety of GMP. The relative intensities of these peaks depend on the pH values of the solution. The pH dependence is explained by the core-level shift of N atoms at specific sites caused by protonation and deprotonation. The experimental spectra are compared with theoretical spectra calculated by using density functional theory for GMP and the other purine-containing nucleotides, adenosine 5{sup ′}-monophosphate, and adenosine 5{sup ′}-triphosphate. The N K-edge XANES spectra for all of these nucleotides are classified by the numbers of N atoms with particular chemical bonding characteristics in the purine moiety.

  4. Antimony(III) complexing with O-bearing organic ligands in aqueous solution: An X-ray absorption fine structure spectroscopy and solubility study

    Science.gov (United States)

    Tella, Marie; Pokrovski, Gleb S.

    2009-01-01

    The stability and structure of aqueous complexes formed by trivalent antimony (Sb III) with carboxylic acids (acetic, adipic, malonic, lactic, oxalic, tartaric, and citric acid), phenols (catechol), and amino acids (glycine) having O- and N-functional groups (carboxyl, alcoholic hydroxyl, phenolic hydroxyl and amine) typical of natural organic matter, were determined at 20 and 60 °C from solubility and X-ray absorption fine structure (XAFS) spectroscopy measurements. In organic-free aqueous solutions and in the presence of acetic, adipic, malonic acids and glycine, both spectroscopic and solubility data are consistent with the dominant formation of Sb III hydroxide species, Sb(OH)3-nn+,Sb(OH)30andSb(OH)4-, at strongly acid, acid-to-neutral and basic pH, respectively, demonstrating negligible complexing with mono-functional organic ligands (acetic) or those having non adjacent carboxylic groups (adipic, malonic). In contrast, in the presence of poly-functional carboxylic and hydroxy-carboxylic acids and catechol, Sb III forms stable 1:1 and 1:2 complexes with the studied organic ligands over a wide pH range typical of natural waters (3 cycle. Stability constants for these species, generated from Sb 2O 3 (rhomb.) solubility experiments, were used to model Sb complexing with natural humic acids possessing the same functional groups as those investigated in this study. Our predictions show that in an aqueous solution of pH between 2 and 10, containing 1 μg/L of Sb and 5 mg/L of dissolved organic carbon (DOC), up to 35% of total dissolved Sb binds to aqueous organic matter via carboxylic and hydroxy-carboxylic groups. This amount of complexed Sb for typical natural DOC concentrations is in agreement with that estimated from dialysis experiments performed with commercial humic acid in our work and those available in the literature for a range of standardized IHSS humic acids. Our results imply that a significant part of Sb is likely to be bound with humic acids via

  5. Investigation of the structure of unilamellar dimyristoylphosphatidylcholine vesicles in aqueous sucrose solutions by small-angle neutron and X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, M. A., E-mail: elena@jinr.ru; Zemlyanaya, E. V.; Zhabitskaya, E. I.; Aksenov, V. L. [Joint Institute for Nuclear Research (Russian Federation)

    2015-01-15

    The structure of a polydispersed population of unilamellar dimyristoylphosphatidylcholine (DMPC) vesicles in sucrose solutions has been investigated by small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). Calculations within the model of separated form factors (SFF) show that the structure of the vesicle system depends strongly on the sucrose concentration.

  6. Structure of Hydrated Zn2+ at the Rutile TiO2 (110)-Aqueous Solution Interface: Comparison of X-ray Standing Wave, X-ray Absorption Spectroscopy, and Density Functional Theory Results

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhan [Argonne National Laboratory (ANL); Fenter, Paul [Argonne National Laboratory (ANL); Kelly, Shelly D [Argonne National Laboratory (ANL); Catalano, Jeffery G. [Argonne National Laboratory (ANL); Bandura, Andrei V. [St. Petersburg State University, St. Petersburg, Russia; Kubicki, James D. [Pennsylvania State University; Sofo, Jorge O. [Pennsylvania State University; Wesolowski, David J [ORNL; Machesky, Michael L. [Illinois State Water Survey, Champaign, IL; Sturchio, N. C. [University of Illinois, Chicago; Bedzyk, Michael J. [Northwestern University, Evanston

    2006-01-01

    Adsorption of Zn{sup 2+} at the rutile TiO{sub 2} (110)-aqueous interface was studied with Bragg-reflection X-ray standing waves (XSW), polarization-dependent surface extended X-ray absorption fine structure (EXAFS) spectroscopy, and density functional theory (DFT) calculations to understand the interrelated issues of adsorption site, its occupancy, ion-oxygen coordination and hydrolysis. At pH 8, Zn{sup 2+} was found to adsorb as an inner-sphere complex at two different sites, i.e., monodentate above the bridging O site and bidentate between two neighboring terminal O sites. EXAFS results directly revealed a four or fivefold first shell coordination environment for adsorbed Zn{sup 2+} instead of the sixfold coordination found for aqueous species at this pH. DFT calculations confirmed the energetic stability of a lower coordination environment for the adsorbed species and revealed that the change to this coordination environment is correlated with the hydrolysis of adsorbed Zn{sup 2+}. In addition, the derived adsorption locations and the occupancy factors of both sites from three methods agree well, with some quantitative discrepancies in the minor site location among the XSW, EXAFS, and DFT methods. Additional XSW measurements showed that the adsorption sites of Zn{sup 2+} were unchanged at pH 6. However, the Zn{sup 2+} partitioning between the two sites changed substantially, with an almost equal distribution between the two types of sites at pH 6 compared to predominantly monodentate occupation at pH 8.

  7. Structure of Hydrated Zn2+ at the Rutile TiO2 (110)-Aqueous Solution Interface: Comparsion of X-ray Standing Wave, X-ray Absorption Spectroscopy, and Density Functional Theory Results

    Energy Technology Data Exchange (ETDEWEB)

    Zhang,Z.; Fenter, P.; Kelly, S.; Catalano, J.; Bandura, A.; Kubicki, J.; Sofo, J.; Wesolowski, D.; Machesky, M.; et al.

    2006-01-01

    Adsorption of Zn{sup 2+} at the rutile TiO2 (110)-aqueous interface was studied with Bragg-reflection X-ray standing waves (XSW), polarization-dependent surface extended X-ray absorption fine structure (EXAFS) spectroscopy, and density functional theory (DFT) calculations to understand the interrelated issues of adsorption site, its occupancy, ion-oxygen coordination and hydrolysis. At pH 8, Zn{sup 2+} was found to adsorb as an inner-sphere complex at two different sites, i.e., monodentate above the bridging O site and bidentate between two neighboring terminal O sites. EXAFS results directly revealed a four or fivefold first shell coordination environment for adsorbed Zn{sup 2+} instead of the sixfold coordination found for aqueous species at this pH. DFT calculations confirmed the energetic stability of a lower coordination environment for the adsorbed species and revealed that the change to this coordination environment is correlated with the hydrolysis of adsorbed Zn{sup 2+}. In addition, the derived adsorption locations and the occupancy factors of both sites from three methods agree well, with some quantitative discrepancies in the minor site location among the XSW, EXAFS, and DFT methods. Additional XSW measurements showed that the adsorption sites of Zn{sup 2+} were unchanged at pH 6. However, the Zn{sup 2+} partitioning between the two sites changed substantially, with an almost equal distribution between the two types of sites at pH 6 compared to predominantly monodentate occupation at pH 8.

  8. Synchrotron x-ray spectroscopy of EuHN O3 aqueous solutions at high temperatures and pressures and Nb-bearing silicate melt phases coexisting with hydrothermal fluids using a modified hydrothermal diamond anvil cell and rail assembly

    Science.gov (United States)

    Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

    2007-01-01

    A modified hydrothermal diamond anvil cell (HDAC) rail assembly has been constructed for making synchrotron x-ray absorption spectroscopy, x-ray fluorescence, and x-ray mapping measurements on fluids or solid phases in contact with hydrothermal fluids up to ???900??C and 700 MPa. The diamond anvils of the HDAC are modified by laser milling grooves or holes, for the reduction of attenuation of incident and fluorescent x rays and sample cavities. The modified HDAC rail assembly has flexibility in design for measurement of light elements at low concentrations or heavy elements at trace levels in the sample and the capability to probe minute individual phases of a multiphase fluid-based system using focused x-ray microbeam. The supporting rail allows for uniform translation of the HDAC, rotation and tilt stages, and a focusing mirror, which is used to illuminate the sample for visual observation using a microscope, relative to the direction of the incident x-ray beam. A structure study of Eu(III) aqua ion behavior in high-temperature aqueous solutions and a study of Nb partitioning and coordination in a silicate melt in contact with a hydrothermal fluid are described as applications utilizing the modified HDAC rail assembly. ?? 2007 American Institute of Physics.

  9. Crystalline self-assembly of organic molecules with metal ions at the air-aqueous solution interface. A grazing incidence X-ray scattering study

    DEFF Research Database (Denmark)

    Weissbuch, I.; Buller, R.; Kjær, K.;

    2002-01-01

    The advent of intense X-rays from synchrotron sources made possible to probe, at the molecular level, the structural aspects of self-assemblies generated at interfaces. Here we present the two-dimensional (2-D) packing arrangements of two-, three- and multi-component organo-metallic self-assembli...... amphiphiles; organization of ionophores in the presence of metal ions in membrane-like environment; self-assembly of 2 x 2 and 3 x 3 silver(I) grid-type complexes generated at the air-solution interface. (C) 2002 Elsevier Science B.V. All rights reserved....

  10. On the attenuation of x-rays and gamma-rays in dilute solutions

    DEFF Research Database (Denmark)

    Gerward, Leif

    1996-01-01

    The theory of X-ray and gamma-ray attenuation in solutions is developed. The rule of mixture for the calculation of mass and linear attenuation coefficients is elaborated in the general case as well as in the limit of extreme dilution. The validity of the latter approximation is illustrated...... by the attenuation of 17.443 keV X-rays in aqueous solutions of NaCl. Copyright (C) 1996 Elsevier Science Ltd...

  11. Summary of existing information on gamma-ray and X-ray attenuation coefficients of solutions

    DEFF Research Database (Denmark)

    Singh, K.; Gerward, Leif

    2002-01-01

    Accurate values of X-ray and gamma-ray attenuation coefficients of different chemicals are required in spectrometry as well as in many other scientific, engineering and medical disciplines involving photon radiation. The current state of knowledge of experimental and theoretical gamma-ray and X......-ray attenuation coefficients in aqueous solutions of salts is presented and exemplified by recent work. The results presented provide a basis for studying X-ray and gamma-ray photon interactions with ions in solution (hydrated ions) rather than ion compounds in solid form....

  12. Temperature and Concentration Effects of Aqueous Solution of Sodium Octanoate on Micelle Formation Measured by Small angle X-ray Scattering

    Directory of Open Access Journals (Sweden)

    A.P. Kuzmenko

    2014-07-01

    Full Text Available Characteristic sizes of sodium octanoate micelles have been determined (by nucleus radius with the use of small angle X-ray scattering technique at various molar concentrations, which are for a spherical shape 1 and nonspherical 1.2 nm, respectively. The value of the critical concentration for micelle formation (CMC2 has been also found equal to 0.7 M.

  13. Time Resolved X-Ray Scattering of molecules in Solution

    DEFF Research Database (Denmark)

    Brandt van Driel, Tim

    The dissertation describes the use of Time-Resolved X-ray Diffuse Scattering (TR-XDS) to study photo-induced structural changes in molecules in solution. The application of the technique is exemplified with experiments on two bimetallic molecules. The main focus is on the data-flow and process...... of bringing the data from measurement to analysis. Bridging the experimental design and challenges of the experiments from X-ray synchrotrons to the newly available X-ray Free Electron Laser sources (XFEL).LCLS in California is the first XFEL to come online and delivers intense 30fs X-ray pulses, orders...... of magnitude shorter than the 100ps X-ray pulses available from synchroton sources. This increase in time-resolution allows for the use of X-ray techniques in a completely new time-domain, where coherent photo-induced changes in structure can be studied on their intrinsic time-scale. Measurements on Rh2(dimen...

  14. Synchrotron X-ray induced solution precipitation of nanoparticles

    CERN Document Server

    Lee, H J; Hwu, Y; Tsai, W L

    2003-01-01

    By irradiating a solution in electroless Ni deposition using synchrotron X-rays, Ni composite was found to nucleate homogeneously and eventually precipitate in the form of nanoparticles. The size of the nanoparticles precipitated is rather uniform (100-300 nm depending on the applied temperature). By the addition of an organic acid, well-dispersed nanoparticles could be effectively deposited on glass substrate. The hydrated electrons (e sub a sub q sup -), products of radiolysis of water molecules by synchrotron X-rays, may be responsible for the effective reduction of the metal ions, resulting in homogeneous nucleation and nanoparticle formation. Our results suggest that synchrotron X-ray can be used to induce solution precipitation of nanoparticles and therefore lead to a new method of producing nanostructured particles and coating.

  15. Chemical Bonding in Aqueous Ferrocyanide: Experimental and Theoretical X-ray Spectroscopic Study

    CERN Document Server

    Engel, Nicholas; Suljoti, Edlira; Garcia-Diez, Raul; Lange, Kathrin M; Atak, Kaan; Golnak, Ronny; Kothe, Alexander; Dantz, Marcus; Kühn, Oliver; Aziz, Emad F

    2013-01-01

    Resonant inelastic X-ray scattering (RIXS) and X-ray absorption (XA) experiments at the iron L- and nitrogen K-edge are combined with high-level first principles restricted active space self-consistent field (RASSCF) calculations for a systematic investigation of the nature of the chemical bond in potassium ferrocyanide in aqueous solution. The atom- and site-specific RIXS excitations allow for direct observation of ligand-to-metal (Fe L-edge) and metal-to-ligand (N K-edge) charge transfer bands and thereby evidence for strong {\\sigma}-donation and {\\pi}-back-donation. The effects are identified by comparing experimental and simulated spectra related to both the unoccupied and occupied molecular orbitals in solution.

  16. Protein structural dynamics revealed by time-resolved X-ray solution scattering.

    Science.gov (United States)

    Kim, Jong Goo; Kim, Tae Wu; Kim, Jeongho; Ihee, Hyotcherl

    2015-08-18

    One of the most important questions in biological science is how a protein functions. When a protein performs its function, it undergoes regulated structural transitions. In this regard, to better understand the underlying principle of a protein function, it is desirable to monitor the dynamic evolution of the protein structure in real time. To probe fast and subtle motions of a protein in physiological conditions demands an experimental tool that is not only equipped with superb spatiotemporal resolution but also applicable to samples in solution phase. Time-resolved X-ray solution scattering (TRXSS), discussed in this Account, fits all of those requirements needed for probing the movements of proteins in aqueous solution. The technique utilizes a pump-probe scheme employing an optical pump pulse to initiate photoreactions of proteins and an X-ray probe pulse to monitor ensuing structural changes. The technical advances in ultrafast lasers and X-ray sources allow us to achieve superb temporal resolution down to femtoseconds. Because X-rays scatter off all atomic pairs in a protein, an X-ray scattering pattern provides information on the global structure of the protein with subangstrom spatial resolution. Importantly, TRXSS is readily applicable to aqueous solution samples of proteins with the aid of theoretical models and therefore is well suited for investigating structural dynamics of protein transitions in physiological conditions. In this Account, we demonstrate that TRXSS can be used to probe real-time structural dynamics of proteins in solution ranging from subtle helix movement to global conformational change. Specifically, we discuss the photoreactions of photoactive yellow protein (PYP) and homodimeric hemoglobin (HbI). For PYP, we revealed the kinetics of structural transitions among four transient intermediates comprising a photocycle and, by applying structural analysis based on ab initio shape reconstruction, showed that the signaling of PYP involves

  17. Solution spectroelectrochemical cell for in situ X-ray absorption fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, M.R.; Soderholm, L. [Argonne National Lab., IL (United States). Chemistry Div.; Song, I. [Case Western Reserve Univ., Cleveland, OH (United States)

    1995-06-12

    A purpose-built spectroelectrochemical cell for in situ fluorescence XAFS (X-ray Absorption Fine Structure) measurements of bulk solution species during constant-potential electrolysis is described. The cell performance was demonstrated by the collection of europium L{sub 3}-edge XANES (X-ray Absorption Near Edge Structure) throughout the course of electrolysis of an aqueous solution of EuCl{sub 3}{center_dot}6H{sub 2}O in 1 M H{sub 2}SO{sub 4}. The europium L{sub 3}-edge resonances reported here for the Eu{sup III} and Eu{sup II} ions demonstrate that their 2p{sub 3/2} {yields} 5d electronic transition probabilities are not the same.

  18. Properties of aqueous nitrate and nitrite from x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jacob W.; Lam, Royce K.; Saykally, Richard J., E-mail: saykally@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Shih, Orion [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Rizzuto, Anthony M. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Prendergast, David [The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-08-28

    Nitrate and nitrite ions are of considerable interest, both for their widespread use in commercial and research contexts and because of their central role in the global nitrogen cycle. The chemistry of atmospheric aerosols, wherein nitrate is abundant, has been found to depend on the interfacial behavior of ionic species. The interfacial behavior of ions is determined largely by their hydration properties; consequently, the study of the hydration and interfacial behavior of nitrate and nitrite comprises a significant field of study. In this work, we describe the study of aqueous solutions of sodium nitrate and nitrite via X-ray absorption spectroscopy (XAS), interpreted in light of first-principles density functional theory electronic structure calculations. Experimental and calculated spectra of the nitrogen K-edge XA spectra of bulk solutions exhibit a large 3.7 eV shift between the XA spectra of nitrate and nitrite resulting from greater stabilization of the nitrogen 1s energy level in nitrate. A similar shift is not observed in the oxygen K-edge XA spectra of NO{sub 3}{sup −} and NO{sub 2}{sup −}. The hydration properties of nitrate and nitrite are found to be similar, with both anions exhibiting a similar propensity towards ion pairing.

  19. Investigation of Propellant and Explosive Solid Solution Systems II X-Ray Studies

    Science.gov (United States)

    1978-03-01

    A\\Yj* ^\\C/*^ ^ 1 tatf AD 7t ott w AD-E400 125 TECHNICAL REPORT ARLCD-TR-77066 INVESTIGATION OF PROPELLANT AND EXPLOSIVE SOLID SOLUTION SYSTEMS...Report ARLCD-TR-77066 2. GOVT ACCESSION NO. *. TITLE (and Subtitle) INVESTIGATION OF PROPELLANT AND EXPLOSIVE SOLID SOLUTION SYSTEMS II X-RAY...Interplanar spacings and x-ray diffraction 9 intensities of AP, KP and their physical mixtures and solid solutions 4 X-ray data of 3 AN: KP solid solution and

  20. Analytical possibilities of different X-ray fluorescence systems for determination of trace elements in aqueous samples pre-concentrated with carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Marguí, E., E-mail: eva.margui@udg.edu [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Zawisza, B.; Skorek, R. [Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice (Poland); Theato, T. [SPECTRO Analytical Instruments GmbH, Boschstr. 10, 47533 Kleve (Germany); Queralt, I. [Laboratory of X-Ray Analytical Applications, Institute of Earth Sciences Jaume Almera, CSIC, Solé Sabarís s/n, 08028 Barcelona (Spain); Hidalgo, M. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Sitko, R. [Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice (Poland)

    2013-10-01

    This study was aimed to achieve improved instrumental sensitivity and detection limits for multielement determination of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Pb and Cd in liquid samples by using different X-ray fluorescence (XRF) configurations (a benchtop energy-dispersive X-ray fluorescence spectrometer, a benchtop polarised energy-dispersive X-ray fluorescence spectrometer and a wavelength-dispersive X-ray fluorescence spectrometer). The preconcentration of metals from liquid solutions consisted on a solid-phase extraction using carbon nanotubes (CNTs) as solid sorbents. After the extraction step, the aqueous sample was filtered and CNTs with the absorbed elements were collected onto a filter paper which was directly analyzed by XRF. The calculated detection limits in all cases were in the low ng mL{sup −1} range. Nevertheless, results obtained indicate the benefits, in terms of sensitivity, of using polarized X-ray sources using different secondary targets in comparison to conventional XRF systems, above all if Cd determination is required. The developed methodologies, using the aforementioned equipments, have been applied for multielement determination in water samples from an industrial area of Poland. - Highlights: • Use of carbon nanotubes for preconcentration of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Pb and Cd • Combination of this preconcentration procedure with different XRF systems • Benefit of using polarized X-ray sources for trace element determination.

  1. Determination of plutonium in nitric acid solutions using energy dispersive L X-ray fluorescence with a low power X-ray generator

    Energy Technology Data Exchange (ETDEWEB)

    Py, J. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, F-25030 Besançon (France); Commissariat à l’Énergie Atomique, Centre de Valduc, F-21120 Is-sur-Tille (France); Groetz, J.-E., E-mail: jegroetz@univ-fcomte.fr [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, F-25030 Besançon (France); Hubinois, J.-C.; Cardona, D. [Commissariat à l’Énergie Atomique, Centre de Valduc, F-21120 Is-sur-Tille (France)

    2015-04-21

    This work presents the development of an in-line energy dispersive L X-ray fluorescence spectrometer set-up, with a low power X-ray generator and a secondary target, for the determination of plutonium concentration in nitric acid solutions. The intensity of the L X-rays from the internal conversion and gamma rays emitted by the daughter nuclei from plutonium is minimized and corrected, in order to eliminate the interferences with the L X-ray fluorescence spectrum. The matrix effects are then corrected by the Compton peak method. A calibration plot for plutonium solutions within the range 0.1–20 g L{sup −1} is given.

  2. Ice Recrystallization in a Solution of a Cryoprotector and Its Inhibition by a Protein: Synchrotron X-Ray Diffraction Study.

    Science.gov (United States)

    Zakharov, Boris; Fisyuk, Alexander; Fitch, Andy; Watier, Yves; Kostyuchenko, Anastasia; Varshney, Dushyant; Sztucki, Michael; Boldyreva, Elena; Shalaev, Evgenyi

    2016-07-01

    Ice formation and recrystallization is a key phenomenon in freezing and freeze-drying of pharmaceuticals and biopharmaceuticals. In this investigation, high-resolution synchrotron X-ray diffraction is used to quantify the extent of disorder of ice crystals in binary aqueous solutions of a cryoprotectant (sorbitol) and a protein, bovine serum albumin. Ice crystals in more dilute (10 wt%) solutions have lower level of microstrain and larger crystal domain size than these in more concentrated (40 wt%) solutions. Warming the sorbitol-water mixtures from 100 to 228 K resulted in partial ice melting, with simultaneous reduction in the microstrain and increase in crystallite size, that is, recrystallization. In contrast to sorbitol solutions, ice crystals in the BSA solutions preserved both the microstrain and smaller crystallite size on partial melting, demonstrating that BSA inhibits ice recrystallization. The results are consistent with BSA partitioning into quasi-liquid layer on ice crystals but not with a direct protein-ice interaction and protein sorption on ice surface. The study shows for the first time that a common (i.e., not-antifreeze) protein can have a major impact on ice recrystallization and also presents synchrotron X-ray diffraction as a unique tool for quantification of crystallinity and disorder in frozen aqueous systems.

  3. In situ characterization of aluminum-containing mineral-microorganism aqueous suspensions using scanning transmission X-ray microscopy.

    Science.gov (United States)

    Yoon, Tae Hyun; Johnson, Stephen B; Benzerara, Karim; Doyle, Colin S; Tyliszczak, Tolek; Shuh, David K; Brown, Gordon E

    2004-11-23

    In situ characterization of colloidal particles under hydrous conditions is one of the key requirements for understanding their state of aggregation and impact on the transport of pollutants in aqueous environments. Scanning transmission X-ray microscopy (STXM) is one of the few techniques that can satisfy this need by providing element- and chemical-state-specific 2-D maps at a spatial resolution better than 50 nm using soft X-rays from synchrotron radiation wiggler or undulator sources tuned to the absorption edges of different elements. X-ray absorption near-edge structure (XANES) spectra can also be collected simultaneously at a similar spatial resolution and can provide phase identification in many cases. In this study, we report STXM images and XANES spectroscopy measurements at or above the Al K-edge (E = 1559.6 eV) of various Al-containing minerals and synthetic oxides [alpha-Al2O3 (corundum), gamma-Al2O3, gamma-AlOOH (boehmite), alpha-Al(OH)3 (bayerite), KAl2(AlSi3O10)(OH)2 (muscovite), (Al,Mg)8(Si4O10)4(OH)8.nH2O (montmorillonite), and Mg6Al2(OH)16CO3.4H2O (hydrotalcite)] and demonstrate the capability of this spectromicroscopic tool to identify different Al-containing mineral colloids in multiphase mixtures in aqueous solution. We also demonstrate that STXM imaging at or above the C K-edge (E = 284.2 eV) and Al K-edge can provide unique information on the interactions between bacteria and Al-containing nanoparticles in aqueous suspensions. STXM images of a mixture of Caulobacter crescentus and montmorillonite and corundum particles just above the C and Al K-edges show that the mineral particles and bacteria are closely associated in aggregates, which is likely due to the binding of bacteria to clay and corundum particles by extracellular polysaccharides.

  4. Microcavity arrays for X-ray diffraction studies of ordering phenomena in confined colloid solutions

    NARCIS (Netherlands)

    Diaz, A.; David, C.; Guo, H.; Keymeulen, H.; Pfeiffer, F.; Wegdam, G.; Weitkamp, T.; van der Veen, J.F.

    2005-01-01

    We present a way to fabricate high-aspect-ratio silicon microcavity arrays which can be used for the investigation of confinement-induced ordering phenomena within colloid solutions. In these studies, the microcavity arrays serve as containers for confinement of the colloid. X-ray diffraction measur

  5. Aqueous Cu(II)-organic complexation studied in situ using soft X-ray and vibrational spectroscopies.

    Science.gov (United States)

    Phillips, Courtney L; Regier, Tom Z; Peak, Derek

    2013-12-17

    In situ aqueous solutions containing copper-ligand mixtures were measured at the Cu L-edge using X-ray absorption near edge structure (XANES) and with attenuated total reflectance infrared (ATR-FTIR) spectroscopies. Copper complexation with environmentally relevant ligands such as EDTA, citrate, and malate provided a bridge between spectroscopic studies and general environmental behavior and will allow for future study of complex environmental samples. XANES results show that the lowest unoccupied molecular orbital (LUMO) energy is governed by the ligand field strength and is related to Lewis acid/base properties of the ligand functional groups. Complementary ATR-FTIR studies confirmed the importance of water molecules in the structure of these Cu-ligand complexes and provided in-depth structural analysis to support the XANES data. Copper-malate is shown to have a 5/6-O-ring structure, and Cu-ethylenediaminetetraacetate has pentadentate coordination. Cu L-edge XANES also revealed direct Cu-N coordination in these aqueous solutions with amide functional groups.

  6. Detection of X-ray photons by solution-processed lead halide perovskites

    Science.gov (United States)

    Yakunin, Sergii; Sytnyk, Mykhailo; Kriegner, Dominik; Shrestha, Shreetu; Richter, Moses; Matt, Gebhard J.; Azimi, Hamed; Brabec, Christoph J.; Stangl, Julian; Kovalenko, Maksym V.; Heiss, Wolfgang

    2015-07-01

    The evolution of real-time medical diagnostic tools such as angiography and computer tomography from radiography based on photographic plates was enabled by the development of integrated solid-state X-ray photon detectors made from conventional solid-state semiconductors. Recently, for optoelectronic devices operating in the visible and near-infrared spectral regions, solution-processed organic and inorganic semiconductors have also attracted a great deal of attention. Here, we demonstrate a possibility to use such inexpensive semiconductors for the sensitive detection of X-ray photons by direct photon-to-current conversion. In particular, methylammonium lead iodide perovskite (CH3NH3PbI3) offers a compelling combination of fast photoresponse and a high absorption cross-section for X-rays, owing to the heavy Pb and I atoms. Solution-processed photodiodes as well as photoconductors are presented, exhibiting high values of X-ray sensitivity (up to 25 μC mGyair-1 cm-3) and responsivity (1.9 × 104 carriers/photon), which are commensurate with those obtained by the current solid-state technology.

  7. Studies of ionic liquid solutions by soft X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Fabio [Departamento de Quimica Fundamental, Instituto de Quimica, Universidade de Sao Paulo, CP 26.077, CEP 05513-970, Sao Paulo, SP (Brazil); Nascimento, Gustavo M. do [Departamento de Quimica Fundamental, Instituto de Quimica, Universidade de Sao Paulo, CP 26.077, CEP 05513-970, Sao Paulo, SP (Brazil)], E-mail: morari@yahoo.com; Santos, Paulo S. [Departamento de Quimica Fundamental, Instituto de Quimica, Universidade de Sao Paulo, CP 26.077, CEP 05513-970, Sao Paulo, SP (Brazil)

    2007-03-15

    Soft X-ray spectroscopies give specific information about the electronic structure around light elements. The high absorption of soft X-rays by almost every molecule, including air, requires studies under vacuum, which represents a great limitation. Solids with high vapor pressure and liquids are very difficult to be studied, making solution chemistry almost neglected. This work explores the use of ionic liquids, organic liquids with very low vapor pressure, as media to study chemical solutions using soft X-ray. N 1s spectra are reported of ionic liquid solutions of 1-methyl-3alkyl-imidazolium cation with different anions and chain lengths, and urea/choline chloride mixtures (a deep eutectic solvent) with several solutes including dyes (Janus Green B and Congo Red), synthetic polymers (polyaniline) and nitrate salts. While there are significant problems with the signal of the solvent, the results do show that it is possible to detect solute signals, and further to see spectral changes attributed to solvent-solute interactions.

  8. Coherent X-ray and laser spectroscopy measurements of diffusion in concentrated alpha-crystallin solutions

    Science.gov (United States)

    Karunaratne, V. N. C.

    The mammalian eye lens is composed of a concentrated solution of water soluble proteins called crystallins. Alpha-crystallin, the most abundant protein found in the lens, plays a crucial role in maintaining lens transparency and lens accommodation. However, alpha-crystallins along with other ocular proteins suffer from irreversible processes such as oxidation. One cause of oxidation is radiation-induced radical formation which alters the inter-molecular interactions, thereby degrading the normal function of ocular proteins. The main goal of this thesis is to quantify molecular scale dynamics of concentrated solutions of alpha-crystallins using coherent X-rays and visible laser light. I believe a detailed analysis of the dynamics pertaining to alpha-crystallin will provide the foundation to understand molecular scale mechanisms that lead to conditions like cataract and presbyopia. I explore the dynamics of concentrated alpha-crystallin solutions by measuring diffusive motion over a range of length scales using Dynamic light scattering (DLS) and X-ray photon correlation spectroscopy (XPCS). To a certain extent, the dynamical properties of crystallins obtained in this manner are consistent with established theories in colloidal physics. However, there are some deviations, which I will address in this thesis. In terms of X-ray data, I employed a new, efficient photon correlation technique to obtain the best possible signal, furthermore this technique is embedded in a stand-alone software program that has the ability to provide real time results, quickly and efficiently with the help of high performance computing resources available at Northern Illinois University (NIU). The technique has potential to be used by the coherent X-ray spectroscopy community in the future. In addition, by using X-ray scattering data, I probe potential modifications and or damage effects on alpha-crystallins due to radiation exposure. The damage analysis methodology described in this thesis

  9. Protein structural dynamics in solution unveiled via 100-ps time-resolved x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hyun Sun; Dashdorj, Naranbaatar; Schotte, Friedrich; Graber, Timothy; Henning, Robert; Anfinruda, Philip (NIH); (UC)

    2010-04-21

    We have developed a time-resolved x-ray scattering diffractometer capable of probing structural dynamics of proteins in solution with 100-ps time resolution. This diffractometer, developed on the ID14B BioCARS (Consortium for Advanced Radiation Sources) beamline at the Advanced Photon Source, records x-ray scattering snapshots over a broad range of q spanning 0.02-2.5 {angstrom}{sup -1}, thereby providing simultaneous coverage of the small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) regions. To demonstrate its capabilities, we have tracked structural changes in myoglobin as it undergoes a photolysis-induced transition from its carbon monoxy form (MbCO) to its deoxy form (Mb). Though the differences between the MbCO and Mb crystal structures are small (rmsd < 0.2 {angstrom}), time-resolved x-ray scattering differences recorded over 8 decades of time from 100 ps to 10 ms are rich in structure, illustrating the sensitivity of this technique. A strong, negative-going feature in the SAXS region appears promptly and corresponds to a sudden > 22 {angstrom}{sup 3} volume expansion of the protein. The ensuing conformational relaxation causes the protein to contract to a volume {approx}2 {angstrom}{sup 3} larger than MbCO within {approx}10 ns. On the timescale for CO escape from the primary docking site, another change in the SAXS/WAXS fingerprint appears, demonstrating sensitivity to the location of the dissociated CO. Global analysis of the SAXS/WAXS patterns recovered time-independent scattering fingerprints for four intermediate states of Mb. These SAXS/WAXS fingerprints provide stringent constraints for putative models of conformational states and structural transitions between them.

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

    CERN Document Server

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

    2013-01-01

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

  11. Picoliter solution deposition for total reflection X-ray fluorescence analysis of semiconductor samples

    Energy Technology Data Exchange (ETDEWEB)

    Sparks, Chris M., E-mail: chris.sparks@svtc.co [Analytical Services, SVTC Technologies, Austin, TX 78741 (United States); Fittschen, Ursula E.A. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Institute of Inorganic and Applied Chemistry, University of Hamburg, 20146 Hamburg (Germany); Havrilla, George J. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2010-09-15

    A deposition system capable of delivering picoliter quantities of solution in programmable arrays was investigated as a method for sample preparation for total reflection X-ray fluorescence (TXRF) spectroscopy. Arrays of trace metals in solution were deposited on Si wafers. The array deposits provide a capability of depositing closely spaced (100 {mu}m or less), typically 5-20 {mu}m diameter droplets in an area that can be matched to the analysis spot of the TXRF detector. The dried depositions were physically characterized and the effect of deposition type and matrix on the TXRF signal was investigated.

  12. Soft X-ray induced modifications of PVA-based microbubbles in aqueous environment: a microspectroscopy study.

    Science.gov (United States)

    Tzvetkov, George; Fernandes, Paulo; Wenzel, Stephan; Fery, Andreas; Paradossi, Gaio; Fink, Rainer H

    2009-02-21

    We use scanning-transmission X-ray microspectroscopy (STXM) for in situ characterization of the physicochemical changes in air-filled poly(vinyl alcohol) (PVA) based microbubbles upon soft X-ray irradiation. The microbubbles were illuminated directly in aqueous suspension with 520 eV X-rays and a continuous shrinkage of the particles with an illumination time/radiation dose was observed. Utilizing the intrinsic absorption properties of the species and the high spatial resolution of the STXM, the modifications of the particles' structure were simultaneously recognized. A thorough characterization of the microbubble volume, membrane thickness and absorption coefficient was performed by quantitative fitting of the radial transmittance profiles of the targeted microbubbles. Apart from the observed volume contraction, there was no significant change in the shell thickness. The chemical changes in the membranes were clarified via C K-edge near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. It was revealed that the observed structural alterations go along with a continuous degradation of the PVA network associated with formation of carbonyl- and carboxyl-containing species as well as an increased content of unsaturated bonds.

  13. The Transient Accereting X-Ray Pulsar XTE J1946+274: Stability of the X-Ray Properties at Low Flux and Updated Orbital Solution

    CERN Document Server

    Marcu-Cheatham, Diana M; Kühnel, Matthias; Müller, Sebastian; Falkner, Sebastian; Caballero, Isabel; Finger, Mark H; Jenke, Peter J; Wilson-Hodge, Colleen A; Fürst, Felix; Grinberg, Victoria; Hemphill, Paul B; Kreykenbohm, Ingo; Klochkov, Dmitry; Rothschild, Richard E; Terada, Yukikatsu; Enoto, Teruaki; Iwakiri, Wataru; Wolff, Michael T; Becker, Peter A; Wood, Kent S; Wilms, Jöern

    2015-01-01

    We present a timing and spectral analysis of the X-ray pulsar XTE J1946+274 observed with Suzaku during an outburst decline in 2010 October and compare with previous results. XTE J1946+274 is a transient X-ray binary consisting of a Be-type star and a neutron star with a 15.75 s pulse period in a 172 d orbit with 2-3 outbursts per orbit during phases of activity. We improve the orbital solution using data from multiple instruments. The X-ray spectrum can be described by an absorbed Fermi-Dirac cutoff power law model along with a narrow Fe K line at 6.4 keV and a weak Cyclotron Resonance Scattering Feature (CRSF) at ~35 keV. The Suzaku data are consistent with the previously observed continuum flux versus iron line flux correlation expected from fluorescence emission along the line of sight. However, the observed iron line flux is slightly higher, indicating the possibility of a higher iron abundance or the presence of non-uniform material. We argue that the source most likely has only been observed in the sub...

  14. Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Wei [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Surface sensitive synchrotron X-ray scattering studies were performed to obtain the distribution of monovalent ions next to a highly charged interface at room temperature. To control surface charge density, lipids, dihexadecyl hydrogen-phosphate (DHDP) and dimysteroyl phosphatidic acid (DMPA), were spread as monolayer materials at the air/water interface, containing CsI at various concentrations. Five decades in bulk concentrations (CsI) are investigated, demonstrating that the interfacial distribution is strongly dependent on bulk concentration. We show that this is due to the strong binding constant of hydronium H3O+ to the phosphate group, leading to proton-transfer back to the phosphate group and to a reduced surface charge. Using anomalous reflectivity off and at the L3 Cs+ resonance, we provide spatial counterion (Cs+) distributions next to the negatively charged interfaces. The experimental ion distributions are in excellent agreement with a renormalized surface charge Poisson-Boltzmann theory for monovalent ions without fitting parameters or additional assumptions. Energy Scans at four fixed momentum transfers under specular reflectivity conditions near the Cs+ L3 resonance were conducted on 10-3 M CsI with DHDP monolayer materials on the surface. The energy scans exhibit a periodic dependence on photon momentum transfer. The ion distributions obtained from the analysis are in excellent agreement with those obtained from anomalous reflectivity measurements, providing further confirmation to the validity of the renormalized surface charge Poisson-Boltzmann theory for monovalent ions. Moreover, the dispersion corrections f0 and f00 for Cs+ around L3 resonance, revealing the local environment of a Cs+ ion in the solution at the interface, were extracted simultaneously with output of ion distributions.

  15. Small and Wide Angle X-ray Scattering studies of biological macromolecules in solution.

    Science.gov (United States)

    Liu, Li; Boldon, Lauren; Urquhart, Melissa; Wang, Xiangyu

    2013-01-08

    In this paper, Small and Wide Angle X-ray Scattering (SWAXS) analysis of macromolecules is demonstrated through experimentation. SWAXS is a technique where X-rays are elastically scattered by an inhomogeneous sample in the nm-range at small angles (typically 0.1 - 5°) and wide angles (typically > 5°). This technique provides information about the shape, size, and distribution of macromolecules, characteristic distances of partially ordered materials, pore sizes, and surface-to-volume ratio. Small Angle X-ray Scattering (SAXS) is capable of delivering structural information of macromolecules between 1 and 200 nm, whereas Wide Angle X-ray Scattering (WAXS) can resolve even smaller Bragg spacing of samples between 0.33 nm and 0.49 nm based on the specific system setup and detector. The spacing is determined from Bragg's law and is dependent on the wavelength and incident angle. In a SWAXS experiment, the materials can be solid or liquid and may contain solid, liquid or gaseous domains (so-called particles) of the same or another material in any combination. SWAXS applications are very broad and include colloids of all types: metals, composites, cement, oil, polymers, plastics, proteins, foods, and pharmaceuticals. For solid samples, the thickness is limited to approximately 5 mm. Usage of a lab-based SWAXS instrument is detailed in this paper. With the available software (e.g., GNOM-ATSAS 2.3 package by D. Svergun EMBL-Hamburg and EasySWAXS software) for the SWAXS system, an experiment can be conducted to determine certain parameters of interest for the given sample. One example of a biological macromolecule experiment is the analysis of 2 wt% lysozyme in a water-based aqueous buffer which can be chosen and prepared through numerous methods. The preparation of the sample follows the guidelines below in the Preparation of the Sample section. Through SWAXS experimentation, important structural parameters of lysozyme, e.g. the radius of gyration, can be analyzed.

  16. ROS enhancement by silicon nanoparticles in X-ray irradiated aqueous suspensions and in glioma C6 cells

    Energy Technology Data Exchange (ETDEWEB)

    David Gara, Pedro M. [CITOMA, Fundacion Avanzar, Instituto de Terapia Radiante S.A., CIO La Plata (Argentina); Garabano, Natalia I. [University of Buenos Aires, Departamento de Quimica Biologica, Facultad de Ciencias Exactas y Naturales, UBA (Argentina); Llansola Portoles, Manuel J. [UNLP, INIFTA, Departamento de Quimica, Facultad de Ciencias Exactas (Argentina); Moreno, M. Sergio [Centro Atomico Bariloche (Argentina); Dodat, Diego; Casas, Oscar R. [CITOMA, Fundacion Avanzar, Instituto de Terapia Radiante S.A., CIO La Plata (Argentina); Gonzalez, Monica C., E-mail: gonzalez@inifta.unlp.edu.ar [UNLP, INIFTA, Departamento de Quimica, Facultad de Ciencias Exactas (Argentina); Kotler, Monica L., E-mail: kotler@qb.fcen.uba.ar [University of Buenos Aires, Departamento de Quimica Biologica, Facultad de Ciencias Exactas y Naturales, UBA (Argentina)

    2012-03-15

    The capability of silicon nanoparticles to increase the yield of reactive species upon 4 MeV X-ray irradiation of aqueous suspensions and C6 glioma cell cultures was investigated. ROS generation was detected and quantified using several specific probes. The particles were characterized by FTIR, XPS, TEM, DLS, luminescence, and adsorption spectroscopy before and after irradiation to evaluate the effect of high energy radiation on their structure. The total concentration of O{sub 2}{sup Bullet -}/HO{sub 2}{sup Bullet}, HO{sup Bullet}, and H{sub 2}O{sub 2} generated upon 4-MeV X-ray irradiation of 6.4 {mu}M silicon nanoparticle aqueous suspensions were on the order of 10 {mu}M per Gy, ten times higher than that obtained in similar experiments but in the absence of particles. Cytotoxic {sup 1}O{sub 2} was generated only in irradiation experiments containing the particles. The particle surface became oxidized to SiO{sub 2} and the luminescence yield reduced with the irradiation dose. Changes in the surface morphology did not affect, within the experimental error, the yields of ROS generated per Gy. X-ray irradiation of glioma C6 cell cultures with incorporated silicon nanoparticles showed a marked production of ROS proportional to the radiation dose received. In the absence of nanoparticles, the cells showed no irradiation-enhanced ROS generation. The obtained results indicate that silicon nanoparticles of <5 nm size have the potential to be used as radiosensitizers for improving the outcomes of cancer radiotherapy. Their capability of producing {sup 1}O{sub 2} upon X-ray irradiation opens novel approaches in the design of therapy strategies.

  17. Composition and structure of Pt chloride complexes in hydrothermal solutions, according to X-ray absorption spectroscopy

    Science.gov (United States)

    Tagirov, B. R.; Trigub, A. L.; Selivanov, P. V.; Koroleva, L. A.

    2017-03-01

    The local atomic environment of Pt in chloride solutions is studied at 25 and 300-350°C via X-ray absorption spectroscopy. A comparison of the Pt L 3-edge XANES spectra for aqueous chloride solutions and reference compounds (K2PtCl4 and K2PtCl6) shows that platinum is in oxidation state +2 at all temperatures, and the complex composition remains unchanged in the experimental range of temperatures (25-350°C) and solution compositions ( m(Cltot) > 0.4 mol kg-1 of H2O). Based on EXAFS spectral analysis, the composition of the complex being dominant in chloride solutions is found to be PtCl4 2- with interatomic Pt-Cl distances of 2.31 ± 0.01 Å, regardless of the temperature. It is concluded that the local environments of Pt and Pd in hydrothermal solutions are similar, and the main form of transfer for these metals is a square-planar complex with four Cl ligands and identical interatomic distances.

  18. Characterization of the Aqueous Uranyl-Silicate Complex Using X-Ray Absorption Spectroscopy and Ab Initio Modeling

    Science.gov (United States)

    Vu, M.; Massey, M.; Huang, P.

    2015-12-01

    The speciation of aqueous uranium ions is an important factor in predicting its mobility and fate in the environment. Two major controls on speciation are pH and the presence of complexing ligands. For the case of aqueous uranyl, UO22+(aq), some common complexes include uranyl-hydroxy, uranyl-carbonato, and uranyl-calcium-carbonato complexes, all of which differ in chemical reactivity and mobility. Uranyl-silicate complexes are also known but remain poorly characterized. In this work, we studied uranyl speciation in a series of aqueous solutions of 0.1 mM uranyl and 2 mM silicate with pH ranging from 4 to 7. Extended X-Ray Absorption Fine Structure (EXAFS) spectra of these samples were recorded at the Stanford Synchrotron Radiation Lightsource (SLAC National Accelerator Laboratory). Of particular note are the uranyl and silicate concentrations employed in our experiments, which are lower than conditions in previously reported EXAFS studies and approach conditions in natural groundwater systems. Preliminary analyses of EXAFS data indicate that uranyl speciation changes across the pH range, consistent with published thermodynamic data that suggest uranyl-silicate complexes may be important for pH ~ 5 and below, while uranyl-carbonato complexes become dominant at circumneutral pH. To guide the interpretation of the EXAFS data, molecular-scale simulations were carried out using density functional theory. We considered two classes of models: (i) hydrated clusters, and (ii) ab initio molecular dynamics simulations of 3D-periodic models involving uranyl and silicate in water. These calculations reveal that at pH ~ 5, the uranyl speciation is the [UO2(H2O)4H3SiO4]+ complex formed by the substitution of an equatorial uranyl water with a monodentate silicate ligand. The evidence from experiments and simulations provide a consistent picture for the uranyl-silicate complex, which may be important in the transport of uranyl in acidic, silicate-rich waters.

  19. Dynamical Solution of the SGEMP Electron Boundary Layer for Linearly Rising and Constant X-Ray Time Histories

    Science.gov (United States)

    1976-12-01

    The time dependent solution is presented for the dynamical behavior of the one dimensional electron boundary layer formed when X-rays knock photoelectrons out of a material surface. The X-ray flux is taken to be either linearly rising in time or constant in time . Two electron energy spectra are considered-exponential and linear-times-exponential. The electrons are assumed to have a cos theta

  20. THE TRANSIENT ACCRETING X-RAY PULSAR XTE J1946+274: STABILITY OF X-RAY PROPERTIES AT LOW FLUX AND UPDATED ORBITAL SOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Marcu-Cheatham, Diana M.; Pottschmidt, Katja [CRESST and Department of Physics, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Kühnel, Matthias; Müller, Sebastian; Falkner, Sebastian; Kreykenbohm, Ingo [Dr. Karl Remeis-Observatory and ECAP, University Erlangen-Nuremberg, Sternwartstr. 7, Bamberg (Germany); Caballero, Isabel [Laboratoire AIM, CEA/IRFU, CNRS/INSU, Université Paris Diderot, CEA DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France); Finger, Mark H. [Universities Space Research Association, National Space Science and Technology Center, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Jenke, Peter J. [University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, AL 35899 (United States); Wilson-Hodge, Colleen A. [Astrophysics Office, ZP 12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Fürst, Felix [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Grinberg, Victoria [Massachusetts Institute of Technology, Kavli Institute for Astrophysics, Cambridge, MA 02139 (United States); Hemphill, Paul B.; Rothschild, Richard E. [University of California, San Diego, Center for Astrophysics and Space Sciences, 9500 Gilman Drive, La Jolla, CA 92093-0424 (United States); Klochkov, Dmitry [Institut für Astronomie und Astrophysik, Universität Tübingen (IAAT), Sand 1, Tübingen (Germany); Terada, Yukikatsu [Graduate School of Science and Engineering, Saitama University, 255 Simo-Ohkubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan); and others

    2015-12-10

    We present a timing and spectral analysis of the X-ray pulsar XTE J1946+274 observed with Suzaku during an outburst decline in 2010 October and compare with previous results. XTE J1946+274 is a transient X-ray binary consisting of a Be-type star and a neutron star with a 15.75 s pulse period in a 172 days orbit with 2–3 outbursts per orbit during phases of activity. We improve the orbital solution using data from multiple instruments. The X-ray spectrum can be described by an absorbed Fermi–Dirac cut-off power-law model along with a narrow Fe Kα line at 6.4 keV and a weak Cyclotron Resonance Scattering Feature (CRSF) at ∼35 keV. The Suzaku data are consistent with the previously observed continuum flux versus iron line flux correlation expected from fluorescence emission along the line of sight. However, the observed iron line flux is slightly higher, indicating the possibility of a higher iron abundance or the presence of non-uniform material. We argue that the source most likely has only been observed in the subcritical (non-radiation dominated) state since its pulse profile is stable over all observed luminosities and the energy of the CRSF is approximately the same at the highest (∼5 × 10{sup 37} erg s{sup −1}) and lowest (∼5 × 10{sup 36} erg s{sup −1}) observed 3–60 keV luminosities.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-20

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

  2. Solution synchrotron x-ray diffraction reveals structural details of lipid domains in ternary mixtures

    Science.gov (United States)

    Yuan, Jing; Kiss, Alexander; Pramudya, Yohanes H.; Nguyen, Lam T.; Hirst, Linda S.

    2009-03-01

    The influence of cholesterol on lipid bilayer structure is significant and the effect of cholesterol on lipid sorting and phase separation in lipid-raft-forming model membrane systems has been well investigated by microscopy methods on giant vesicles. An important consideration however is the influence of fluorescence illumination on the phase state of these lipids and this effect must be carefully minimized. In this paper, we show that synchrotron x-ray scattering on solution lipid mixtures is an effective alternative technique for the identification and characterization of the lo (liquid ordered) and ld (liquid disordered) phases. The high intensity of synchrotron x rays allows the observation of up to 5 orders of diffraction from the lo phase, whereas only two are clearly visible when the ld phase alone is present. This data can be collected in ˜1min/sample , allowing rapid generation of phase data. In this paper, we measure the lamellar spacing in both the liquid-ordered and liquid-disordered phases simultaneously, as a function of cholesterol concentration in two different ternary mixtures. We also observe evidence of a third gel-phaselike population at 10-12mol% cholesterol and determine the thickness of the bilayer for this phase. Importantly we are able to look at phase coexistence in the membrane independent of photoeffects.

  3. Solution Synchrotron X-ray Diffraction Reveals Structural Details of Lipid Domains in Ternary Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, J.; Kiss, A; Pramudya, Y; Nguyen, L; Hirst, L

    2009-01-01

    The influence of cholesterol on lipid bilayer structure is significant and the effect of cholesterol on lipid sorting and phase separation in lipid-raft-forming model membrane systems has been well investigated by microscopy methods on giant vesicles. An important consideration however is the influence of fluorescence illumination on the phase state of these lipids and this effect must be carefully minimized. In this paper, we show that synchrotron x-ray scattering on solution lipid mixtures is an effective alternative technique for the identification and characterization of the l o (liquid ordered) and l d (liquid disordered) phases. The high intensity of synchrotron x rays allows the observation of up to 5 orders of diffraction from the l o phase, whereas only two are clearly visible when the l d phase alone is present. This data can be collected in approximately 1 min/sample, allowing rapid generation of phase data. In this paper, we measure the lamellar spacing in both the liquid-ordered and liquid-disordered phases simultaneously, as a function of cholesterol concentration in two different ternary mixtures. We also observe evidence of a third gel-phaselike population at 10-12 mol % cholesterol and determine the thickness of the bilayer for this phase. Importantly we are able to look at phase coexistence in the membrane independent of photoeffects.

  4. Uranium and plutonium solution assays by transmission-corrected x-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Ryon, R W; Ruhter, W D; Rudenko, V; Sirontinin, A; Petrov, A A

    1999-09-08

    We have refined and tested a previously developed x-ray fluorescence analysis technique for uranium and plutonium solutions that compensates for variations in the absorption of the exciting gamma rays and fluorescent x-rays. We use {sup 57}Co to efficiently excite the K lines of the elements, and a mixed {sup 57}Co plus {sup 153}Gd transmission source to correct for variations in absorption. The absorption correction is a unique feature of our technique. It is possible to accurately calibrate the system with a single solution standard. There does not need to be a close match in composition (i.e., absorption) between the standard(s) and solutions to be analyzed. Specially designed equipment incorporates a planar intrinsic germanium detector, excitation and transmission radioisotopes, and specimen holder. The apparatus can be inserted into a rubber glove of a glovebox, keeping the apparatus outside and the solutions inside the glovebox, thereby protecting the user and the equipment from possible contamination. An alternate design may be used in chemical reprocessing plants, providing continuous monitoring, by measuring the trans-actinides through stainless steel piping. This technique has been tested at the Bochvar Research Institute of Inorganic Materials in Moscow for possible use in the Russian complex of nuclear facilities. This is part of a cooperative program between laboratories in the United States and Russia to strengthen systems of nuclear materials protection, control, and accountability (MPC and A). A part of this program is to accurately measure and track inventories of materials, thus the need for good non-destructive analytical techniques such as the one described here.

  5. Aqueous phase synthesis of upconversion nanocrystals through layer-by-layer epitaxial growth for in vivo X-ray computed tomography

    KAUST Repository

    Li, Feifei

    2013-05-21

    Lanthanide-doped core-shell upconversion nanocrystals (UCNCs) have tremendous potential for applications in many fields, especially in bio-imaging and medical therapy. As core-shell UCNCs are mostly synthesized in organic solvents, tedious organic-aqueous phase transfer processes are usually needed for their use in bio-applications. Herein, we demonstrate the first example of one-step synthesis of highly luminescent core-shell UCNCs in the "aqueous" phase under mild conditions using innocuous reagents. A microwave-assisted approach allowed for layer-by-layer epitaxial growth of a hydrophilic NaGdF4 shell on NaYF4:Yb, Er cores. During this process, surface defects of the nanocrystals could be gradually passivated by the homogeneous shell deposition, resulting in obvious enhancement in the overall upconversion emission efficiency. In addition, the up-down conversion dual-mode luminescent NaYF4:Yb, Er@NaGdF4:Ce, Ln (Eu, Tb, Sm, Dy) nanocrystals were also synthesized to further validate the successful formation of the core-shell structure. More significantly, based on their superior solubility and stability in water solution, high upconversion efficiency and Gd-doped predominant X-ray absorption, the as-prepared NaYF4:Yb, Er@NaGdF4 core-shell UCNCs exhibited high contrast in in vitro cell imaging and in vivo X-ray computed tomography (CT) imaging, demonstrating great potential as multiplexed luminescent biolabels and CT contrast agents.

  6. X-ray computed tomography system for laboratory small-object imaging: Enhanced tomography solutions.

    Science.gov (United States)

    Kharfi, F; Yahiaoui, M L; Boussahoul, F

    2015-07-01

    A portable X-ray tomography system has been installed and actually being tested at our medical imaging laboratory. This tomography system employs a combination of scintillator screen and CCD camera as image detector. The limit of spatial resolution of 290 μm of this imaging system is determined by the establishment of its modulation transfer function (MTF). In this work, we present attempts to address some issues such as limited resolution and low contrast through the development of affordable post-acquisition solutions based on the application of super-resolution method (projection onto convex sets, POCS) to create new projections set enabling the reconstruction of an improved 3D image in terms of contrast, resolution and noise. In addition to small-object examination, this tomography system is used for hands-on training activities involving students and scientists.

  7. Small-angle x-ray scattering study of polymer structure: Carbosilane dendrimers in hexane solution

    Science.gov (United States)

    Shtykova, E. V.; Feigin, L. A.; Volkov, V. V.; Malakhova, Yu. N.; Streltsov, D. R.; Buzin, A. I.; Chvalun, S. N.; Katarzhanova, E. Yu.; Ignatieva, G. M.; Muzafarov, A. M.

    2016-09-01

    The three-dimensional organization of monodisperse hyper-branched macromolecules of regular structure—carbosilane dendrimers of zero, third, and sixth generations—has been studied by small-angle X-ray scattering (SAXS) in solution. The use of modern methods of SAXS data interpretation, including ab initio modeling, has made it possible to determine the internal architecture of the dendrimers in dependence of the generation number and the number of cyclosiloxane end groups (forming the shell of dendritic macromolecules) and show dendrimers to be spherical. The structural results give grounds to consider carbosilane dendrimers promising objects for forming crystals with subsequent structural analysis and determining their structure with high resolution, as well as for designing new materials to be used in various dendrimer-based technological applications.

  8. In situ X-ray diffraction based investigation of crystallization in solution deposited PZT thin films

    Science.gov (United States)

    Nittala, Krishna

    Solution deposited PZT based thin films have potential applications in embedded decoupling capacitors and pulse discharge capacitors. During solution deposition, precursor solution is deposited onto a substrate to obtain an amorphous film. The film is then crystallized by heating it at a high temperature (˜600 - 700°C). Conditions during the crystallization anneal such as precursor stoichiometry in solution, heating rate and adhesion layer in the substrate are known to influence phase and texture evolution in these films. However, a mechanistic understanding of the changes taking place in these thin films during crystallization is lacking. A better understanding of the crystallization processes in these thin films could enable tailoring the properties of thin films to suit specific applications. To explore the crystallization process in solution deposited PZT thin films, high temperature in situ laboratory and synchrotron X-ray diffraction based techniques were developed. Taking advantage of the high X-ray flux available at synchrotron facilities such as beamline 6-ID-B, Advanced Photon Source, Argonne National Laboratory, crystalline phases formed in the thin films during crystallization at the high heating rates (0.5 -- 60°C/s) typically used during film processing could be measured. Using a 2-D detector for these measurements allowed the simultaneous measurement of both phase and texture information during crystallization. Analytical treatment of the unconventional diffraction geometry used during the synchrotron based measurements was performed to develop methodologies for quantitative estimation of texture components. The nominal lead content in the starting solutions and the heating rate used during crystallization was observed to influence the sequence of phases formed during crystallization of the films. In films crystallized at fast heating rates, titanium segregation, probably due to diffusion of titanium from the adhesion layer, was observed. To

  9. The small angle x-ray scattering of globular proteins in solution during heat denaturation

    Science.gov (United States)

    Banuelos, Jose; Urquidi, Jacob

    2008-10-01

    The ability of proteins to change their conformation in response to changes in their environment has consequences in biological processes like metabolism, chemical regulation in cells, and is believed to play a role in the onset of several neurodegenerative diseases. Factors such as a change in temperature, pressure, and the introduction of ions into the aqueous environment of a protein can give rise to the folding/unfolding of a protein. As a protein unfolds, the ratio of nonpolar to polar groups exposed to water changes, affecting a protein's thermodynamic properties. Using small angle x-ray scattering (SAXS), we are currently studying the intermediate protein conformations that arise during the folding/unfolding process as a function of temperature for five globular proteins. Trends in the observed intermediate structures of these globular proteins, along with correlations with data on protein thermodynamics may help elucidate shared characteristics between all proteins in the folding/unfolding process. Experimental design considerations will be discussed and preliminary results for some of these systems will be presented.

  10. Structural stability of soybean lipoxygenase-1 in solution as probed by small angle X-ray scattering.

    Science.gov (United States)

    Dainese, Enrico; Sabatucci, Annalaura; van Zadelhoff, Guus; Angelucci, Clotilde Beatrice; Vachette, Patrice; Veldink, Gerrit A; Agrò, Alessandro Finazzi; Maccarrone, Mauro

    2005-05-27

    Soybean lipoxygenase-1 (LOX-1) is used widely as a model for studying the structural and functional properties of the homologous family of lipoxygenases. The crystallographic structure revealed that LOX-1 is organized in a beta-sheet N-terminal domain and a larger, mostly helical, C-terminal domain. Here, we describe the overall structural characterization of native unliganded LOX-1 in solution, using small angle X-ray scattering (SAXS). We show that the scattering pattern of the unliganded enzyme in solution does not display any significant difference compared with that calculated from the crystal structure, and that models of the overall shape of the protein calculated ab initio from the SAXS pattern provide a close envelope to the crystal structure. These data, demonstrating that LOX-1 has a compact structure also in solution, rule out any major motional flexibility of the LOX-1 molecule in aqueous solutions. In addition we show that eicosatetraynoic acid, an irreversible inhibitor of lipoxygenase used to mimic the effect of substrate binding, does not alter the overall conformation of LOX-1 nor its ability to bind to membranes. In contrast, the addition of glycerol (to 5%, v/v) causes an increase in the binding of the enzyme to membranes without altering its catalytic efficiency towards linoleic acid nor its SAXS pattern, suggesting that the global conformation of the enzyme is unaffected. Therefore, the compact structure determined in the crystal appears to be essentially preserved in these various solution conditions. During the preparation of this article, a paper by M. Hammel and co-workers showed instead a sharp difference between crystal and solution conformations of rabbit 15-LOX-1. The possible cause of this difference might be the presence of oligomers in the rabbit lipoxygenase preparations.

  11. Precipitation of neptunium dioxide from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, K E

    1999-12-01

    Tens of thousands of metric tons of highly radioactive, nuclear waste have been generated in the US. Currently, there is no treatment or disposal facility for these wastes. Of the radioactive elements in high-level nuclear waste, neptunium (Np) is of particular concern because it has a long half-life and may potentially be very mobile in groundwaters associated with a proposed underground disposal site at Yucca Mountain, Nevada. Aqueous Np concentrations observed in previous, short-term solubility experiments led to calculated potential doses exceeding proposed long-term regulatory limits. However, thermodynamic data for Np at 25 C showed that these observed aqueous Np concentrations were supersaturated with respect to crystalline NpO{sub 2}. It was hypothesized that NpO{sub 2} is the thermodynamically stable solid phase in aqueous solution, but it is slow to form in an aqueous solution of NpO{sub 2}{sup +} on the time scale of previous experiments. The precipitation of NpO{sub 2} would provide significantly lower aqueous Np concentrations leading to calculated doses below proposed regulatory limits. To test this hypothesis, solubility experiments were performed at elevated temperature to accelerate any slow precipitation kinetics. Ionic NpO{sub 2}{sup +} (aq) was introduced into very dilute aqueous solutions of NaCl with initial pH values ranging from 6 to 10. The reaction vessels were placed in an oven and allowed to react at 200 C until steady-state aqueous Np concentrations were observed. In all cases, aqueous Np concentrations decreased significantly from the initial value of 10{sup {minus}4} M. The solids that formed were analyzed by x-ray powder diffraction, x-ray absorption spectroscopy, and scanning electron microscopy. The solids were determined to be high-purity crystals of NpO{sub 2}. This is the first time that crystalline NpO{sub 2} has been observed to precipitate from NpO{sub 2}{sup +}(aq) in near-neutral aqueous solutions. The results obtained

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

    Directory of Open Access Journals (Sweden)

    Palash Sanphui

    2014-03-01

    Full Text Available 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

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

    Science.gov (United States)

    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

  14. Dynamic Conformations of Nucleosome Arrays in Solution from Small-Angle X-ray Scattering

    Science.gov (United States)

    Howell, Steven C.

    Chromatin conformation and dynamics remains unsolved despite the critical role of the chromatin in fundamental genetic functions such as transcription, replication, and repair. At the molecular level, chromatin can be viewed as a linear array of nucleosomes, each consisting of 147 base pairs (bp) of double-stranded DNA (dsDNA) wrapped around a protein core and connected by 10 to 90 bp of linker dsDNA. Using small-angle X-ray scattering (SAXS), we investigated how the conformations of model nucleosome arrays in solution are modulated by ionic condition as well as the effect of linker histone proteins. To facilitate ensemble modeling of these SAXS measurements, we developed a simulation method that treats coarse-grained DNA as a Markov chain, then explores possible DNA conformations using Metropolis Monte Carlo (MC) sampling. This algorithm extends the functionality of SASSIE, a program used to model intrinsically disordered biological molecules, adding to the previous methods for simulating protein, carbohydrates, and single-stranded DNA. Our SAXS measurements of various nucleosome arrays together with the MC generated models provide valuable solution structure information identifying specific differences from the structure of crystallized arrays.

  15. Automated nanoliter solution deposition for total reflection X-ray fluorescence analysis of semiconductor samples

    Energy Technology Data Exchange (ETDEWEB)

    Sparks, Chris M. [Process Characterization Laboratory, ATDF, Austin, TX 78741 (United States)]. E-mail: chris.sparks@atdf.com; Gondran, Carolyn H. [Process Characterization Laboratory, ATDF, Austin, TX 78741 (United States); Havrilla, George J. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hastings, Elizabeth P. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2006-11-15

    In this study, a BioDot BioJet dispensing system was investigated as a nanoliter sample deposition method for total reflection X-ray fluorescence (TXRF) analysis. The BioDot system was programmed to dispense arrays of 20 nL droplets of sample solution on Si wafers. Each 20 nL droplet was approximately 100 {mu}m in diameter. A 10 x 10 array (100 droplets) was deposited and dried in less than 2 min at room temperature and pressure, demonstrating the efficiency of the automated deposition method. Solutions of various concentrations of Ni and Ni in different matrices were made from stock trace element standards to investigate of the effect of the matrix on the TXRF signal. The concentrations were such that the levels of TXRF signal saturation could be examined. Arrays were deposited to demonstrate the capability of drying 100 {mu}L of vapor phase decomposition-like residue in the area of a typical TXRF detector.

  16. Treatment of Aqueous Solutions

    NARCIS (Netherlands)

    Van Spronsen, J.; Witkamp, G.J.

    2013-01-01

    The invention is directed to a process for the recovery or removal of one or more crystallizable compounds from an aqueous solution containing, apart from the said crystallizable compounds, one or more organic or inorganic scale- forming or scale-inducing materials having a lower solubility in water

  17. Sub-100-ps structural dynamics of horse heart myoglobin probed by time-resolved X-ray solution scattering

    Science.gov (United States)

    Oang, Key Young; Kim, Kyung Hwan; Jo, Junbeom; Kim, Youngmin; Kim, Jong Goo; Kim, Tae Wu; Jun, Sunhong; Kim, Jeongho; Ihee, Hyotcherl

    2015-01-01

    Here we report sub-100-ps structural dynamics of horse heart myoglobin revealed by time-resolved X-ray solution scattering. By applying the time-slicing scheme to the measurement and subsequent deconvolution, we investigate the protein structural dynamics that occur faster than the X-ray temporal pulse width of synchrotrons (~100 ps). The singular value decomposition analysis of the experimental data suggests that two structurally distinguishable intermediates are formed within 100 ps. In particular, the global structural change occurring on the time scale of 70 ps is identified. PMID:25678733

  18. X-ray imager using solution processed organic transistor arrays and bulk heterojunction photodiodes on thin, flexible plastic substrate

    NARCIS (Netherlands)

    Gelinck, G.H.; Kumar, A.; Moet, D.; Steen, J.L. van der; Shafique, U.; Malinowski, P.E.; Myny, K.; Rand, B.P.; Simon, M.; Rütten, W.; Douglas, A.; Jorritsma, J.; Heremans, P.L.; Andriessen, H.A.J.M.

    2013-01-01

    We describe the fabrication and characterization of large-area active-matrix X-ray/photodetector array of high quality using organic photodiodes and organic transistors. All layers with the exception of the electrodes are solution processed. Because it is processed on a very thin plastic substrate o

  19. Advanced ensemble modelling of flexible macromolecules using X-ray solution scattering

    Directory of Open Access Journals (Sweden)

    Giancarlo Tria

    2015-03-01

    Full Text Available Dynamic ensembles of macromolecules mediate essential processes in biology. Understanding the mechanisms driving the function and molecular interactions of `unstructured' and flexible molecules requires alternative approaches to those traditionally employed in structural biology. Small-angle X-ray scattering (SAXS is an established method for structural characterization of biological macromolecules in solution, and is directly applicable to the study of flexible systems such as intrinsically disordered proteins and multi-domain proteins with unstructured regions. The Ensemble Optimization Method (EOM [Bernadó et al. (2007. J. Am. Chem. Soc. 129, 5656–5664] was the first approach introducing the concept of ensemble fitting of the SAXS data from flexible systems. In this approach, a large pool of macromolecules covering the available conformational space is generated and a sub-ensemble of conformers coexisting in solution is selected guided by the fit to the experimental SAXS data. This paper presents a series of new developments and advancements to the method, including significantly enhanced functionality and also quantitative metrics for the characterization of the results. Building on the original concept of ensemble optimization, the algorithms for pool generation have been redesigned to allow for the construction of partially or completely symmetric oligomeric models, and the selection procedure was improved to refine the size of the ensemble. Quantitative measures of the flexibility of the system studied, based on the characteristic integral parameters of the selected ensemble, are introduced. These improvements are implemented in the new EOM version 2.0, and the capabilities as well as inherent limitations of the ensemble approach in SAXS, and of EOM 2.0 in particular, are discussed.

  20. Electronic structure and optical properties of CdS{sub x}Se{sub 1−x} solid solution nanostructures from X-ray absorption near edge structure, X-ray excited optical luminescence, and density functional theory investigations

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, M. W. [DESY (Deutsches Elektronen-Synchrotron), FS-PEX, Notkestrasse 85, 22607 Hamburg (Germany); Yiu, Y. M., E-mail: yyiu@uwo.ca; Sham, T. K. [Department of Chemistry, University of Western Ontario, London, ON N6A5B7 (Canada); Ward, M. J. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Liu, L. [Institute of Functional Nano and Soft Materials (FUNSOM) and Soochow University-Western University Center for Synchrotron Radiation Research, Soochow University, Suzhou, Jiangsu, 215123 (China); Hu, Y. [Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N2V3 (Canada); Zapien, J. A. [Center Of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR (China); Liu, Yingkai [Institute of Physics and Electronic Information, Yunnan Normal University, Kunming, Yunnan, 650500 (China)

    2014-11-21

    The electronic structure and optical properties of a series of iso-electronic and iso-structural CdS{sub x}Se{sub 1−x} solid solution nanostructures have been investigated using X-ray absorption near edge structure, extended X-ray absorption fine structure, and X-ray excited optical luminescence at various absorption edges of Cd, S, and Se. It is found that the system exhibits compositions, with variable local structure in-between that of CdS and CdSe accompanied by tunable optical band gap between that of CdS and CdSe. Theoretical calculation using density functional theory has been carried out to elucidate the observations. It is also found that luminescence induced by X-ray excitation shows new optical channels not observed previously with laser excitation. The implications of these observations are discussed.

  1. Influence of supersaturation on structure of sodium aluminate solutions with medium concentration: a solution X-ray diffraction study

    Institute of Scientific and Technical Information of China (English)

    李洁; 陈启元; 尹周澜; 张平民; 李元高

    2002-01-01

    Influence of supersaturation on the structure of a series of freshly prepared supersaturated sodium aluminate solutions with medium concentration was investigated by solution X-ray diffraction. Experimental results show that the basic Al-containing species in all kinds of supersaturated solution is four-coordinated ions. Opposite to Al-O distance contracted in highly concentrated solution, a little expand of the Al-O distance from 1.75 to 1.85 occurs with increasing supersaturation, which is consistent with the occurrence of oligomeric aluminate species. Meanwhile, O-O distance in the first shell of H2O-H2O(OH) in supersaturated sodium aluminate solution is obviously longer than in hydroxide sodium solution and becomes longer and longer with increasing supersaturation. Na-O bond length is about 2.4 and changes little with supersaturation. The reason for Al-O bond expanding with supersaturation and its influence on the stability of solution was discussed.

  2. X-ray Emission from Eta Carinae near Periastron in 2009 I: A Two State Solution

    CERN Document Server

    Hamaguchi, Kenji; Russell, Christopher; Pollock, Andrew M T; Gull, Theodore R; Teodoro, Mairan; Madura, Thomas I; Damineli, Augusto; Pittard, Julian M

    2014-01-01

    X-ray emission from the supermassive binary system Eta Carinae declines sharply around periastron. This X-ray minimum has two distinct phases - the lowest flux phase in the first ~3 weeks and a brighter phase thereafter. In 2009, the Chandra X-ray Observatory monitored the first phase five times and found the lowest observed flux at ~1.9e-12 ergs cm-2 s-1 (3-8 keV). The spectral shape changed such that the hard band above ~4 keV dropped quickly at the beginning and the soft band flux gradually decreased to its lowest observed value in ~2 weeks. The hard band spectrum had begun to recover by that time. This spectral variation suggests that the shocked gas producing the hottest X-ray gas near the apex of the wind-wind collision (WWC) is blocked behind the dense inner wind of the primary star, which later occults slightly cooler gas downstream. Shocked gas previously produced by the system at earlier orbital phases is suggested to produce the faint residual X-ray emission seen when the emission near the apex is ...

  3. In-Situ Synchrotron X-ray Study of the Phase and Texture Evolution of Ceria and Superconductor Films Deposited by Chemical Solution Method

    DEFF Research Database (Denmark)

    Yue, Zhao; Grivel, Jean-Claude; He, Dong

    2012-01-01

    In situ synchrotron x-ray diffraction is used to study the phase and texture formation of ceria based films and superconductor films deposited by the chemical solution method on technical substrates. Combined analysis using in situ synchrotron x-ray diffraction, thermogravimetry/differential ther......In situ synchrotron x-ray diffraction is used to study the phase and texture formation of ceria based films and superconductor films deposited by the chemical solution method on technical substrates. Combined analysis using in situ synchrotron x-ray diffraction, thermogravimetry...

  4. Solvation dynamics monitored by combined X-ray spectroscopies and scattering: photoinduced spin transition in aqueous [Fe(bpy)3]2+

    DEFF Research Database (Denmark)

    Bressler, C.; Gawelda, W.; Galler, A.;

    2014-01-01

    We have studied the photoinduced low spin (LS) to high spin (HS) conversion of aqueous Fe(bpy)3 with pulse-limited time resolution. In a combined setup permitting simultaneous X-ray diffuse scattering (XDS) and spectroscopic measurements at a MHz repetition rate we have unraveled the interplay be...

  5. In Situ Structural Characterization of Ferric Iron Dimers in Aqueous Solutions

    DEFF Research Database (Denmark)

    Zhu, Mengqiang; Puls, Brendan W.; Frandsen, Cathrine

    2013-01-01

    The structure of ferric iron (Fe3+) dimers in aqueous solutions has long been debated. In this work, we have determined the dimer structure in situ in aqueous solutions using extended X-ray absorption fine structure (EXAFS) spectroscopy. An Fe K-edge EXAFS analysis of 0.2 M ferric nitrate solutio...

  6. Polycrystalline lead iodide films produced by solution evaporation and tested in the mammography X-ray energy range

    Science.gov (United States)

    Condeles, J. F.; Mulato, M.

    2016-02-01

    Lead iodide polycrystalline films have been deposited on corning glass substrates using solution evaporation in oven. Films 6 μm-thick were obtained with full coverage of the substrates as verified by scanning electron microscopy. Some pin-holes were observable. X-ray diffraction revealed a crystalline structure corresponding to the 4 H-PbI2 polytype formation. Polarized Raman scattering experiments indicated a lamellar structure. Anisotropy was also investigated using depolarization ratio calculations. The optical and electrical properties of the samples were investigated using photoluminescence and dark conductivity as a function of temperature, respectively. Activation energies of 0.10 up to 0.89 eV were related to two main electrical transport mechanisms. Films were also exposed to X-ray irradiation in the mammography X-ray energy range. The detector produced was also exposed to X-ray from 5 mR up to 1450 mR. A linear response was observed as a function of dose with a slope of 0.52 nA/mm2 per mR.

  7. A developer solution for tank processing of x-ray film under ambient, tropical conditions.

    Science.gov (United States)

    Wayrynen, R E; McKinney, W E

    1976-05-01

    A modification of a proprietary 90-sec. x-ray-film developer which permits its use as a hand-tank developer at ambient temperatures between 21.6 degrees-30.6 degrees C (80 degrees-100 degrees F) is described. This processing technique is useful in tropical countries where the control of developer temperature is particularly difficult.

  8. X-ray CT-Derived Soil Characteristics Explain Varying Air, Water, and Solute Transport Properties across a Loamy Field

    DEFF Research Database (Denmark)

    Paradelo Pérez, Marcos; Katuwal, Sheela; Møldrup, Per;

    2016-01-01

    The characterization of soil pore space geometry is important for explaining fluxes of air, water, and solutes through soil and understanding soil hydrogeochemical functions. X-ray computed tomography (CT) can be applied for this characterization, and in this study CT-derived parameters were used...... be factors that increased the uncertainty of the relationships. Nevertheless, the results confirmed the potential of X-ray CT visualization techniques for estimating fluxes through soil at the field scale....... to explain water, air, and solute transport through soil. Forty-five soil columns (20 by 20 cm) were collected from an agricultural field in Estrup, Denmark, and subsequently scanned using a medical CT scanner. Nonreactive tracer leaching experiments were performed in the laboratory along with measurements...

  9. X-ray characterization of tripyridinium bis[tetrabromidoferrate(III)] bromide asymmetric unit in solution by Debye function analysis

    Science.gov (United States)

    Baniasadi, F.; Sahraei, N.; Fathi, M. B.; Tehranchi, M. M.; Safari, N.; Amani, V.

    2016-09-01

    Abundant asymmetric unit of the [FeBr4]2[py.H]3Br magnetic molecule in the acetonitrile solvent was characterized via Debye function analysis (DFA) of the X-ray powder diffraction pattern from dilute solution. A diluted solution of the material in acetonitrile solvent has been prepared to reduce, as far as possible, the interaction between the molecular units. The X-ray diffraction from the sample was measured and Debye function simulations of three out of ten chemically plausible molecular units were observed to suitably comply with the experimental results. These three configurations were further optimized with first-principles method in the framework of density functional theory (DFT) and the most stable structure according to the calculated total energy is presented.

  10. Instability of Solution of Phase Retrieval in Direct Diffraction Phase-Contrast Imaging with Partially Coherent X-Ray Source

    Institute of Scientific and Technical Information of China (English)

    GUO Hua; HAN Shen-Sheng

    2006-01-01

    The theoretical model of direct diffraction phase-contrast imaging with partially coherent x-ray source is expressedby an operator of multiple integral. It is presented that the integral operator is linear. The problem of its phaseretrieval is described by solving an operator equation of multiple integral. It is demonstrated that the solution ofthe phase retrieval is unstable. The numerical simulation is performed and the result validates that the solutionof the phase retrieval is unstable.

  11. Numerical Solution of the Radiative Transfer Equation: X-Ray Spectral Formation from Cylindrical Accretion onto a Magnetized Neutron Star

    Science.gov (United States)

    Fairnelli, R.; Ceccobello, C.; Romano, P.; Titarchuk, L.

    2011-01-01

    Predicting the emerging X-ray spectra in several astrophysical objects is of great importance, in particular when the observational data are compared with theoretical models. This requires developing numerical routines for the solution of the radiative transfer equation according to the expected physical conditions of the systems under study. Aims. We have developed an algorithm solving the radiative transfer equation in the Fokker-Planck approximation when both thermal and bulk Comptonization take place. The algorithm is essentially a relaxation method, where stable solutions are obtained when the system has reached its steady-state equilibrium. Methods. We obtained the solution of the radiative transfer equation in the two-dimensional domain defined by the photon energy E and optical depth of the system pi using finite-differences for the partial derivatives, and imposing specific boundary conditions for the solutions. We treated the case of cylindrical accretion onto a magnetized neutron star. Results. We considered a blackbody seed spectrum of photons with exponential distribution across the accretion column and for an accretion where the velocity reaches its maximum at the stellar surface and at the top of the accretion column, respectively. In both cases higher values of the electron temperature and of the optical depth pi produce flatter and harder spectra. Other parameters contributing to the spectral formation are the steepness of the vertical velocity profile, the albedo at the star surface, and the radius of the accretion column. The latter parameter modifies the emerging spectra in a specular way for the two assumed accretion profiles. Conclusions. The algorithm has been implemented in the XPEC package for X-ray fitting and is specifically dedicated to the physical framework of accretion at the polar cap of a neutron star with a high magnetic field (approx > 10(exp 12) G). This latter case is expected to be of typical accreting systems such as X-ray

  12. Guest–Host Interactions Investigated by Time-Resolved X-ray Spectroscopies and Scattering at MHz Rates

    DEFF Research Database (Denmark)

    Haldrup, Martin Kristoffer; Vanko, G.; Gawelda, W.

    2012-01-01

    We have studied the photoinduced low spin (LS) to high spin (HS) conversion of [Fe(bipy)3]2+ in aqueous solution. In a laser pump/X-ray probe synchrotron setup permitting simultaneous, time-resolved X-ray diffuse scattering (XDS) and X-ray spectroscopic measurements at a 3.26 MHz repetition rate,...

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

    Directory of Open Access Journals (Sweden)

    Liubov A Dadinova

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

  14. X-Ray Crystallography Reagent

    Science.gov (United States)

    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.

  15. Can X-rays provide a solution to the abundance discrepancy problem in photoionised nebulae?

    CERN Document Server

    Ercolano, Barbara

    2009-01-01

    We re-examine the well-known discrepancy between ionic abundances determined via the analysis of recombination lines (RLs) and collisionally excited lines (CELs). We show that abundance variations can be mimicked in a {\\it chemically homogeneous} medium by the presence of dense X-ray irradiated regions which present different ionisation and temperature structures from those of the more diffuse medium they are embedded in, which is predominantly ionised by extreme-ultraviolet radiation. The presence of X-ray ionised dense clumps or filaments also naturally explains the lower temperatures often measured from O {\\sc ii} recombination lines and from the Balmer jump when compared to temperatures determined by CELs. We discuss the implications for abundances determined via the analysis of CELs and RLs and provide a simple analytical procedure to obtain upwards corrections for CEL-determined abundance. While we show that the abundance discrepancy factor (ADF) and the Balmer Jump temperature determined from observati...

  16. Improvement of a high pressure cell with diamond windows for solution X-ray scattering of proteins

    CERN Document Server

    Nishikawa, Y; Inoko, Y; Moritoki, M

    2001-01-01

    An improved high pressure (up to 500 MPa) cell with diamond windows was developed for small-angle X-ray scattering of protein solutions. When the diamond window was subjected to high pressure, many streaks of parasitic scattering appeared. By changing the wavelength and performing simulations, it was concluded that they are Kossel lines. In order to obtain quantitative scattering data, it is essential that Kossel lines do not interfere with the beamstop. The performance of the improved cell was tested by using Apo-ferritin solutions.

  17. Micellization of Zonyl FSN-100 Fluorosurfactant in Aqueous Solutions

    OpenAIRE

    Skvarla, Juraj; Uchman, M.; Procházka, K.; Tošner, Z.; Garamus, V. M.; Pispas, S.; Štěpánek, M.

    2014-01-01

    We report on micellization of nonionic fluorosurfactant Zonyl FSN-100 in aqueous solutions studied by means of NMR spectroscopy, light and small-angle X-ray scattering, surface tension measurements, isothermal titration calorimetry and fluorescence spectroscopy. The results allow for determination of basic parameters of Zonyl FSN-100 association like critical micellar concentration, size and association number of Zonyl FSN-100 micelles which have a core–shell structure with the core of fluoro...

  18. Astrophysical parameters and orbital solution of the peculiar X-ray transient IGR J00370+6122

    CERN Document Server

    González-Galán, A; Castro, N; Simón-Díaz, S; Lorenzo, J; Vilardell, F

    2014-01-01

    BD+6073 is the optical counterpart of the X-ray source IGR J00370+6122, a probable accretion-powered X-ray pulsar. The X-ray light curve of this binary system shows clear periodicity at 15.7 d, which has been interpreted as repeated outbursts around the periastron of an eccentric orbit. We obtained high-resolution spectra of BD+6073 at different epochs. We used the FASTWind code to generate a stellar atmosphere model to fit the observed spectrum and obtain physical magnitudes. The synthetic spectrum was used as a template for cross-correlation with the observed spectra to measure radial velocities. The radial velocity curve provided an orbital solution for the system. We have also analysed the RXTE/ASM and Swift/BAT light curves to confirm the stability of the periodicity. BD +6073 is a BN0.7 Ib low-luminosity supergiant located at an approximate distance of 3.1 kpc, in the CasOB4 association. We derive Teff=24000 K and log gc=3.0, and chemical abundances consistent with a moderately high level of evolution. ...

  19. An X-Ray Tomography Based Modeling Solution For Chemical Vapor Infiltration Of Ceramic Matrix Composites

    Science.gov (United States)

    Ros, William; Vignoles, Gérard L.; Germain, Christian

    2010-05-01

    A numerical tool for the simulation of Chemical Vapor Infiltration of carbon/carbon composites is introduced. The structure of the fibrous medium can be studied by high resolution X-Ray Computed Micro Tomography. Gas transport in various regimes is simulated by a random walk technique whilst the morphological evolution of the fluid/solid interface is handled by a Marching Cube technique. The program can be used to evaluate effective diffusivity and first order reaction rate. The numerical tool is validated by comparing computed effective properties of a straight slit pore with reactive walls to their analytical expression. Simulation of CVI processing of a real complex media is then presented.

  20. Characterization of few transient black hole candidates during their X-ray outbursts with TCAF Solution

    CERN Document Server

    Debnath, Dipak; Chakrabarti, S K; Jana, A; Molla, A A; Chatterjee, D

    2016-01-01

    The theoretical concept of Chakrabarti-Titarchuk two Component Advective Flow (TCAF) model was introduced around two decade ago in mid-90s. Recently after the inclusion of TCAF model into XSPEC as an additive table model, we find that it is quite capable to fit spectra from different phases of few transient black hole candidates (TBHCs) during their outbursts. This quite agrees with our theoretical understanding. Here, a brief summary of our recent studies of spectral and temporal properties of few TBHCs during their X-ray outbursts with TCAF will be discussed.

  1. Structure in defocused beams of x-ray mirrors: causes and possible solutions

    Science.gov (United States)

    Sutter, John P.; Alcock, Simon G.; Rust, Fiona; Wang, Hongchang; Sawhney, Kawal

    2014-09-01

    Grazing incidence mirrors are now a standard optic for focusing X-ray beams. Both bimorph and mechanically bendable mirrors are widely used at Diamond Light Source because they permit a wide choice of focal lengths. They can also be deliberately set out of focus to enlarge the X-ray beam, and indeed many beamline teams now wish to generate uniform beam spots of variable size. However, progress has been slowed by the appearance of fine structure in these defocused beams. Measurements showing the relationship between the medium-frequency polishing error and this structure over a variety of beam sizes will be presented. A theoretical model for the simulations of defocused beams from general mirrors will then be developed. Not only the figure error and its first derivative the slope error, but also the second derivative, the curvature error, must be considered. In conclusion, possible ways to reduce the defocused beam structure by varying the actuators' configuration and settings will be discussed.

  2. Induced alignment of a solution-cast discotic hexabenzocoronene derivative for electronic devices investigated by surface X-ray diffraction

    DEFF Research Database (Denmark)

    Bunk, Oliver; Nielsen, Martin Meedom; Sølling, Theis Ivan

    2003-01-01

    A surface X-ray diffraction study is presented showing that highly ordered and uniaxially aligned hexa(3,7-dimethyl-octanyl)hexa-peri-hexabenzocoronene (HBC-C8,2) films can be fabricated by crystallization from solution onto friction-transferred poly(tetrafluoroethylene) (PTFE) layers. Three...... crystalline HBC-C8,2 majority phases result. In all three phases, the HBC-C8,2 molecules self-organize into columns which are uniaxially aligned along the direction defined by the PTFE macromolecules of the substrate. The three phases are quite similar, the major difference being their orientation...

  3. Solution X-ray scattering (S/WAXS) and structure formation in protein dynamics

    CERN Document Server

    Nasedkin, Alexandr; Niemi, Antti J; Peng, Xubiao

    2016-01-01

    We propose to develop mean field theory in combination with Glauber algorithm, to model and interpret protein dynamics and structure formation in small to wide angle x-ray scattering (S/WAXS) experiments. We develop the methodology by analysing the Engrailed homeodomain protein as an example. We demonstrate how to interpret S/WAXS data with a good precision and over an extended temperature range. We explain experimentally observed phenomena in terms of protein phase structure, and we make predictions for future experiments how the scattering data behaves at different ambient temperature values. We conclude that a combination of mean field theory with Glauber algorithm has the potential to develop into a highly accurate, computationally effective and predictive tool for analysing S/WAXS data. Finally, we compare our results with those obtained previously in an all-atom molecular dynamics simulation.

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

    Science.gov (United States)

    Ventura, Irit; Bianco-Peled, Havazelet

    2015-06-01

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

  5. Surface complexation and precipitate geometry for aqueous Zn(II) sorption on ferrihydrite I: X-ray absorption extended fine structure spectroscopy analysis

    Science.gov (United States)

    Waychunas, G.A.; Fuller, C.C.; Davis, J.A.

    2002-01-01

    "Two-line" ferrihydrite samples precipitated and then exposed to a range of aqueous Zn solutions (10-5 to 10-3 M), and also coprecipitated in similar Zn solutions (pH 6.5), have been examined by Zn and Fe K-edge X-ray absorption spectroscopy. Typical Zn complexes on the surface have Zn-O distances of 1.97(0.2) A?? and coordination numbers of about 4.0(0.5), consistent with tetrahedral oxygen coordination. This contrasts with Zn-O distances of 2.11(.02) A?? and coordination numbers of 6 to 7 in the aqueous Zn solutions used in sample preparation. X-ray absorption extended fine structure spectroscopy (EXAFS) fits to the second shell of cation neighbors indicate as many as 4 Zn-Fe neighbors at 3.44(.04) A?? in coprecipitated samples, and about two Zn-Fe neighbors at the same distance in adsorption samples. In both sets of samples, the fitted coordination number of second shell cations decreases as sorption density increases, indicating changes in the number and type of available complexing sites or the onset of competitive precipitation processes. Comparison of our results with the possible geometries for surface complexes and precipitates suggests that the Zn sorption complexes are inner sphere and at lowest adsorption densities are bidentate, sharing apical oxygens with adjacent edge-sharing Fe(O,OH)6 octahedra. Coprecipitation samples have complexes with similar geometry, but these are polydentate, sharing apices with more than two adjacent edge-sharing Fe(O,OH)6 polyhedra. The results are inconsistent with Zn entering the ferrihydrite structure (i.e., solid solution formation) or formation of other Zn-Fe precipitates. The fitted Zn-Fe coordination numbers drop with increasing Zn density with a minimum of about 0.8(.2) at Zn/(Zn + Fe) of 0.08 or more. This change appears to be attributable to the onset of precipitation of zinc hydroxide polymers with mainly tetrahedral Zn coordination. At the highest loadings studied, the nature of the complexes changes further

  6. Local Effects in the X-ray Absorption Spectrum of CaCl2, MgCl2, and NaCl Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kulik, H J; Correa Tedesco, A A; Schwegler, E; Prendergast, D; Galli, G

    2010-04-12

    Both first principles molecular dynamics and theoretical X-ray absorption spectroscopy have been used to investigate the aqueous solvation of cations in 0.5 M MgCl{sub 2}, CaCl{sub 2}, and NaCl solutions. We focus here on the species-specific effects that Mg{sup 2+}, Ca{sup 2+}, and Na{sup +}, have on the X-ray absorption spectrum of the respective solutions. For the divalent cations, we find that the hydrogen bonding characteristics of the more rigid magnesium first shell water molecules differ from those in the more flexible solvation shell surrounding calcium. In particular, the first solvation shell water molecules of calcium are accessible to forming acceptor hydrogen bonds, and this results in an enhancement of a post-edge peak near 540 eV. The absence of acceptor hydrogen bonds for magnesium first shell water molecules provides an explanation for the experimental and theoretical observation of a lack of enhancement at the post-main-edge peak. For the sodium monovalent cation we find that the broad tilt angle distribution results in a broadening of post-edge features, despite populations in donor-and-acceptor configurations consistent with calcium. We also present the re-averaged spectra of the MgCl{sub 2}, CaCl{sub 2}, and NaCl solutions and show that trends apparent with increasing concentration (0.5 M, 2.0 M, 4.0 M) are consistent with experiment. Finally, we examine more closely both the effect that cation coordination number has on the hydrogen bonding network and the relative perturbation strength of the cations on lone pair oxygen orbitals.

  7. Radiation chemical effects of X-rays on liquids

    Energy Technology Data Exchange (ETDEWEB)

    Holroyd, R.A.; Preses, J.M.

    1998-11-01

    This review describes some of the chemical changes induced by photoelectrons which are released in liquids when X-rays are absorbed. Both experimental studies and theory are discussed. In part 1, the basic processes occurring upon absorption of X-rays are described. Parts 2 and 3 deal with hydrocarbon liquids; in part 2 the ion yields, including effects at K-edges, and in part 3, the yields of excited states. Part 4 discusses chemical effects of X-rays in aqueous solutions. The authors end with a summary of future needs and directions.

  8. Red mercuric iodide crystals obtained by isothermal solution evaporation: Characterization for mammographic X-ray imaging detectors

    Energy Technology Data Exchange (ETDEWEB)

    Caldeira, A.M.F.; Ugucioni, J.C.; Mulato, M.

    2014-02-11

    Millimeter-sized mercury iodide crystals were obtained by the isothermal evaporation technique using dimethylformamide (DMF), diethyl-ether/DMF mixture and THF. Different concentrations (18 mM and 400 mM) and solution temperature (25–80 °C) were used to obtain varied evaporation rates (0.1×10{sup −4}–5000×10{sup −4} ml/h). Different crystal sizes and shapes were obtained by changing solvents, mixture and initial solution volume. According to X-ray diffraction the samples are monocrystalline. The top surface was investigated by SEM. Optical band-gaps above 2 eV were obtained from photoacoustic spectroscopy. Photoluminescence spectra indicated band-to-band electronic transitions, and the presence of sub-band gap states. Excitons, structural defects and the presence of impurities are discussed and correlated to the electrical measurements. Crystals obtained using pure DMF as solvent showed better general properties, including under the exposure to mammographic X-ray energy range that led to sensibility of about 25 μC/Rcm{sup 2}.

  9. Skull x-ray

    Science.gov (United States)

    X-ray - head; X-ray - skull; Skull radiography; Head x-ray ... There is low radiation exposure. X-rays are monitored and regulated to provide the minimum amount of radiation exposure needed to produce the image. Most ...

  10. Neck x-ray

    Science.gov (United States)

    X-ray - neck; Cervical spine x-ray; Lateral neck x-ray ... There is low radiation exposure. X-rays are monitored so that the lowest amount of radiation is used to produce the image. Pregnant women and ...

  11. Direct Observation of Cooperative Protein Structural Dynamics of Homodimeric Hemoglobin from 100 ps to 10 ms with Pump-Probe X-ray Solution Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Hwan; Muniyappan, Srinivasan; Oang, Key Young; Kim, Jong Goo; Nozawa, Shunsuke; Sato, Tokushi; Koshihara, Shin-ya; Henning, Robert; Kosheleva, Irina; Ki, Hosung; Kim, Youngmin; Kim, Tae Wu; Kim, Jeongho; Adachi, Shin-ichi; Ihee, Hyotcherl [JS; (JSTA); (KAIST); (UC); (KEK)

    2012-05-29

    Proteins serve as molecular machines in performing their biological functions, but the detailed structural transitions are difficult to observe in their native aqueous environments in real time. For example, despite extensive studies, the solution-phase structures of the intermediates along the allosteric pathways for the transitions between the relaxed (R) and tense (T) forms have been elusive. In this work, we employed picosecond X-ray solution scattering and novel structural analysis to track the details of the structural dynamics of wild-type homodimeric hemoglobin (HbI) from the clam Scapharca inaequivalvis and its F97Y mutant over a wide time range from 100 ps to 56.2 ms. From kinetic analysis of the measured time-resolved X-ray solution scattering data, we identified three structurally distinct intermediates (I1, I2, and I3) and their kinetic pathways common for both the wild type and the mutant. The data revealed that the singly liganded and unliganded forms of each intermediate share the same structure, providing direct evidence that the ligand photolysis of only a single subunit induces the same structural change as the complete photolysis of both subunits does. In addition, by applying novel structural analysis to the scattering data, we elucidated the detailed structural changes in the protein, including changes in the heme-heme distance, the quaternary rotation angle of subunits, and interfacial water gain/loss. The earliest, R-like I1 intermediate is generated within 100 ps and transforms to the R-like I2 intermediate with a time constant of 3.2 ± 0.2 ns. Subsequently, the late, T-like I3 intermediate is formed via subunit rotation, a decrease in the heme-heme distance, and substantial gain of interfacial water and exhibits ligation-dependent formation kinetics with time constants of 730 ± 120 ns for the fully photolyzed form and 5.6 ± 0.8 μs for the partially photolyzed form. For

  12. A high-repetition rate scheme for synchrotron-based picosecond laser pump/x-ray probe experiments on chemical and biological systems in solution.

    Science.gov (United States)

    Lima, Frederico A; Milne, Christopher J; Amarasinghe, Dimali C V; Rittmann-Frank, Mercedes Hannelore; van der Veen, Renske M; Reinhard, Marco; Pham, Van-Thai; Karlsson, Susanne; Johnson, Steven L; Grolimund, Daniel; Borca, Camelia; Huthwelker, Thomas; Janousch, Markus; van Mourik, Frank; Abela, Rafael; Chergui, Majed

    2011-06-01

    We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection at MHz repetition rates. The use of a high-power picosecond laser operating at an integer fraction of the repetition rate of the storage ring allows exploitation of up to two orders of magnitude more x-ray photons than in previous schemes based on the use of kHz lasers. Consequently, we demonstrate an order of magnitude increase in the signal-to-noise of time-resolved XAS of molecular systems in solution. This makes it possible to investigate highly dilute samples at concentrations approaching physiological conditions for biological systems. The simplicity and compactness of the scheme allows for straightforward implementation at any synchrotron beamline and for a wide range of x-ray probe techniques, such as time-resolved diffraction or x-ray emission studies.

  13. Improved fitting of solution X-ray scattering data to macromolecular structures and structural ensembles by explicit water modeling.

    Science.gov (United States)

    Grishaev, Alexander; Guo, Liang; Irving, Thomas; Bax, Ad

    2010-11-10

    A new procedure, AXES, is introduced for fitting small-angle X-ray scattering (SAXS) data to macromolecular structures and ensembles of structures. By using explicit water models to account for the effect of solvent, and by restricting the adjustable fitting parameters to those that dominate experimental uncertainties, including sample/buffer rescaling, detector dark current, and, within a narrow range, hydration layer density, superior fits between experimental high resolution structures and SAXS data are obtained. AXES results are found to be more discriminating than standard Crysol fitting of SAXS data when evaluating poorly or incorrectly modeled protein structures. AXES results for ensembles of structures previously generated for ubiquitin show improved fits over fitting of the individual members of these ensembles, indicating these ensembles capture the dynamic behavior of proteins in solution.

  14. Electron microscopic and solution X-ray scattering observations on the structure of hepatitis B surface antigen

    Energy Technology Data Exchange (ETDEWEB)

    Aggerbeck, L.P.; Peterson, D.L.

    1985-02-01

    The structure of the small, spherical hepatitis B surface antigen was studied by negative staining, freeze-fracture and freeze-etching electron microscopy and solution X-ray scattering techniques. The protein appears to be organized at the surface into a small number of morphological subunits which display two- and threefold axes of symmetry. The mean particle size was 18.3 nm by negative staining and 19.6 nm by freeze-fracture electron microscopy. The diameter of the individual subunits was about 7.5 nm with an intersubunit distance of about 10.0 nm. The lipid is distributed more homogeneously. Some heterogeneity of the particle structure is apparent which may be due to a slightly variable lipid-protein composition or incomplete or defective particle formation.

  15. Investigation of the amorphous to crystalline phase transition of chemical solution deposited Pb(Zr30Ti70)O3 thin films by soft x-ray absorption and soft x-ray emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schneller, T.; Schneller, T.; Kohlstedt, H.; Petraru, A.; Waser, R.; Guo, J.; Denlinger, J.; Learmonth, T.; Glans, Per-Andres; Smith, K. E.

    2008-08-01

    Chemical solution deposited (CSD) complex oxide thin films attract considerable interest in various emerging fields as for example, fuel cells, ferroelectric random access memories or coated conductors. In the present paper the results of soft-x-ray spectroscopy between 100 eV and 500 eV on the amorphous to crystalline phase transition of ferroelectric PbZr{sub 0.3}Ti{sub 0.7}O{sub 3} (PZT) thin films are presented. Five CSD samples derived from the same wafer coated with a PZT film pyrolyzed at 350 C were heat treated at different temperatures between 400 C and 700 C. At first the sample were morphologically and electrically characterized. Subsequently the soft-x-ray absorption and emission experiments were performed at the undulator beamline 8.0 of the Advanced Light Source of the Lawrence Berkeley National Laboratory. Soft-x-ray absorption spectra were acquired for the Ti L{sub 2,3-}, O K-, and C K-edge thresholds by using simultaneously the total electron yield (TEY) and total fluorescence yield (TFY) detection methods. For two samples, annealed at 400 C and 700 C, respectively, the resonant inelastic soft-x-ray spectroscopy (RIXS) was applied for various excitation energies near the Ti L-, O K-edges. We observed clear evidence of a rutile phase at untypically low temperatures. This rutile phase transforms into the perovskite phase upon increasing annealing temperature. These results are discussed in the framework of current microscopic models of the PZT (111) texture selection.

  16. Pervaporation of Aqueous Solution of Acetaldehyde Through ZSM-5 Filled PDMS Composite Membrane

    Institute of Scientific and Technical Information of China (English)

    伍艳辉; 谭惠芬; 李佟茗; 金源

    2012-01-01

    Hydrophobic ZSM-5 zeolite filled polydimethylsiloxane (PDMS) composite membranes with Nylon micro-filtration membrane as the support layer were prepared to separate acetaldehyde from its aqueous solution. The composite membranes were characterized by Fourier transform infrared spectroscopy and X-ray diffraction. Their structural morphology and thermal stability were also examined. The swelling study showed that the composite membranes presented higher degree of swelling in aqueous solution of acetaldehyde than in pure water at 25℃,

  17. Dynamic Conformations of Nucleosome Arrays in Solution from Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Howell, Steven C. [George Washington Univ., Washington, DC (United States)

    2016-01-31

    We set out to determine quantitative information regarding the dynamic conformation of nucleosome arrays in solution using experimental SAXS. Toward this end, we developed a CG simulation algorithm for dsDNA which rapidly generates ensembles of structures through Metropolis MC sampling of a Markov chain.

  18. Preparation of Ultrafine Cobalt Powder by Chemical Reduction in Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nanocrystalline cobalt powders have been prepared from aqueous solution by reducing their corresponding metal salts under suitable conditions. The experimental conditions have been studied in detail. X-ray powder diffraction patterns show that the cobalt powder is hexagonal crystallite. The average particle size of the ultrafine cobalt powder is 55 nm.

  19. Applied radiation physics: The use of x-rays for the structural characterization of aqueous emulsions and the development of new insect sterilization protocols

    Science.gov (United States)

    Brar, Ramaninder K.

    X-rays have great potential of applications in a wide variety of fields. This dissertation presents the use of x-rays for the structural characterization of aqueous emulsions and for insect sterilization. The stabilization of hydrophobic colloids, such as oil droplets, in water has attracted scientist for a variety of scientific, pharmaceutical and industrial applications. Several studies have been done to understand the stability of oil-in-water emulsions. The work of Pashley and his coworkers has demonstrated that the removal of dissolved gasses from water enhances the dispersion of hydrophobic oil in water and these surfactant-free emulsions do not lose their stability when the previously removed gasses are reintroduced. However, very little is known about the structure and stability of these emulsions over time or even to what extent they form. The formation of a stable emulsion in the complete absence of a surfactant could provide an alternative approach to a physiologically safe drug carrier. In this dissertation we demonstrate the formation of stabilized surfactant-free degassed emulsions of hydrocarbons - hexane, heptane and octane and silicone oil in ultra-pure water. The enhancement of dispersion of oil droplets by degassing was large for highly hydrophobic silicone oil. Turbidity measurements and small angle x-ray scattering results show that the uniformly dispersed oil droplets weakly aggregate over a period of several hours. Gentle perturbation re-generates the dispersion to nearly initial conditions. The control of insect species for the protection of crops, livestock, and prevention of disease, such as dengue fever and malaria, is a high priority in today's global economy. Sterile Insect Technique (SIT), a method of insect extermination without the use of pesticides, has proven very effective in eradicating certain dipteran insect populations. However, when standard sterilization methods developed for dipterans are applied to mosquito populations

  20. Chest X Ray?

    Science.gov (United States)

    ... this page from the NHLBI on Twitter. Chest X Ray A chest x ray is a fast and painless imaging test ... tissue scarring, called fibrosis. Doctors may use chest x rays to see how well certain treatments are ...

  1. X-Rays

    Science.gov (United States)

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

  2. Medical X-Rays

    Science.gov (United States)

    ... Benefits The discovery of X-rays and the invention of CT represented major advances in medicine. X- ... in X-ray and CT Examinations — X-ray definition, dose measurement, safety precautions, risk, and consideration with ...

  3. 2010 Water & Aqueous Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Dor Ben-Amotz

    2010-08-13

    Water covers more than two thirds of the surface of the Earth and about the same fraction of water forms the total mass of a human body. Since the early days of our civilization water has also been in the focus of technological developments, starting from converting it to wine to more modern achievements. The meeting will focus on recent advances in experimental, theoretical, and computational understanding of the behavior of the most important and fascinating liquid in a variety of situations and applications. The emphasis will be less on water properties per se than on water as a medium in which fundamental dynamic and reactive processes take place. In the following sessions, speakers will discuss the latest breakthroughs in unraveling these processes at the molecular level: Water in Solutions; Water in Motion I and II; Water in Biology I and II; Water in the Environment I and II; Water in Confined Geometries and Water in Discussion (keynote lecture and poster winners presentations).

  4. In situ x-ray diffraction of solution-derived ferroelectric thin films for quantitative phase and texture evolution measurement

    Science.gov (United States)

    Nittala, Krishna; Mhin, Sungwook; Jones, Jacob L.; Robinson, Douglas S.; Ihlefeld, Jon F.; Brennecka, Geoff L.

    2012-11-01

    An in situ measurement technique is developed and presented, which utilizes x-rays from a synchrotron source with a two-dimensional detector to measure thin film microstructural and crystallographic evolution during heating. A demonstration experiment is also shown wherein the measured diffraction patterns are used to describe phase and texture evolution during heating and crystallization of solution-derived thin films. The diffraction images are measured sequentially while heating the thin film with an infrared lamp. Data reduction methodologies and representations are also outlined to extract phase and texture information from the diffraction images as a function of time and temperature. These techniques and data reduction methods are demonstrated during crystallization of solution-derived lead zirconate titanate ferroelectric thin films heated at a rate of 30 °C/min and using an acquisition time of 8 s. During heating and crystallization, a PtxPb type phase was not observed. A pyrochlore phase was observed prior to the formation and growth of the perovskite phase. The final crystallized films are observed to have both 111 and 100 texture components. The in situ measurement methodology developed in this work allows for acquiring diffraction images in times as low as 0.25 s and can be used to investigate changes during crystallization at faster heating rates. Moreover, the experiments are shown to provide unique information during materials processing.

  5. Hardware solutions for the 65k pixel X-ray camera module of 75 μm pixel size

    Science.gov (United States)

    Kasinski, K.; Maj, P.; Grybos, P.; Koziol, A.

    2016-02-01

    We present three hardware solutions designed for a detector module built with a 2 cm × 2 cm hybrid pixel detector built from a single 320 or 450 μ m thick silicon sensor designed and fabricated by Hamamatsu and two UFXC32k readout integrated circuits (128 × 256 pixels with 75μ m pitch, designed in CMOS 130 nm at AGH-UST). The chips work in a single photon counting mode and provide ultra-fast X-ray imaging. The presented hardware modules are designed according to requirements of various tests and applications: ṡDevice A: a fast and flexible system for tests with various radiation sources. ṡDevice B: a standalone, all-in-one imaging device providing three standard interfaces (USB 2.0, Ethernet, Camera Link) and up to 640 MB/s bandwidth. ṡDevice C: a prototype large-area imaging system. The paper shows the readout system structure for each case with highlighted circuit board designs with details on power distribution and cooling on both FR4 and LTCC (low temperature co-fired ceramic) based circuits.

  6. Quantitative Characterization of Configurational Space Sampled by HIV-1 Nucleocapsid Using Solution NMR, X-ray Scattering and Protein Engineering.

    Science.gov (United States)

    Deshmukh, Lalit; Schwieters, Charles D; Grishaev, Alexander; Clore, G Marius

    2016-06-03

    Nucleic-acid-related events in the HIV-1 replication cycle are mediated by nucleocapsid, a small protein comprising two zinc knuckles connected by a short flexible linker and flanked by disordered termini. Combining experimental NMR residual dipolar couplings, solution X-ray scattering and protein engineering with ensemble simulated annealing, we obtain a quantitative description of the configurational space sampled by the two zinc knuckles, the linker and disordered termini in the absence of nucleic acids. We first compute the conformational ensemble (with an optimal size of three members) of an engineered nucleocapsid construct lacking the N- and C-termini that satisfies the experimental restraints, and then validate this ensemble, as well as characterize the disordered termini, using the experimental data from the full-length nucleocapsid construct. The experimental and computational strategy is generally applicable to multidomain proteins. Differential flexibility within the linker results in asymmetric motion of the zinc knuckles which may explain their functionally distinct roles despite high sequence identity. One of the configurations (populated at a level of ≈40 %) closely resembles that observed in various ligand-bound forms, providing evidence for conformational selection and a mechanistic link between protein dynamics and function.

  7. Corrosion behavior of bulk metallic glasses in different aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The corrosion behavior of as-cast fully amorphous, structural relaxed amorphous and crystallized Fe65.5Cr4Mo4Ga4P12C5B5.5 bulk metallic glasses (BMGs) in NaCl, HCl and NaOH solutions was investigated by electrochemical polarization and immersion methods. X-ray photoelectron spectroscopy measurements was used to analyze the changes of the elements on the alloy surface before and after immersion in various solutions. The corrosion resistance of the Fe65.5Cr4Mo4Ga4P12C5B5.5 BMG was better than its structural relaxation/crystallization counterparts and common alloys (such as stainless steel, carbonized steel, and steel) in the selected aqueous solutions. The high corrosion resistance of this alloy in corrosive solutions leads to the formation of Fe-, Cr- and Mo-enriched protective thin surface films.

  8. Structure of concentrated aqueous solutions of scandium chloride

    Science.gov (United States)

    Smirnov, P. R.; Grechin, O. V.

    2017-03-01

    It is shown via X-ray diffraction that aqueous solutions of scandium chloride form ionic associates in a wide range of concentrations. It is established that the Sc3+ ion coordination number increases upon dilution to 8.2 at an unchanged Sc3+-OH2 distance of 0.215 nm. The second coordination sphere of the cation forms at an average distance of 0.420 nm. The number of solvent molecules in the sphere logically increases during dilution. It is concluded that the anion does not form its own sphere in highly concentrated solutions. This coordination sphere begins to form only in solutions with moderate concentrations at a distance of 0.315 nm, and it contains six water molecules in diluted solutions.

  9. Lyotropic, liquid crystalline nanostructures of aqueous dilutions of SMEDDS revealed by small-angle X-ray scattering: impact on solubility and drug release.

    Science.gov (United States)

    Goddeeris, Caroline; Goderis, Bart; Van den Mooter, Guy

    2010-05-12

    The present study was conducted to characterise the liquid crystalline phases that occur upon diluting a SMEDDS and to elucidate the role of these phases on drug solubilisation and release. Small-angle X-ray scattering (SAXS) was used to probe the structures in aqueous dilutions of 3 SMEDDS consisting of propylene glycol mono- and dicaprylate and mono- and dicaprate (PGDCDC) and d-alpha-tocopheryl polyethylene glycol succinate 1000 (TPGS 1000), polysorbate 80 (P80) or polyoxyl 40 hydrogenated castor oil (P40HC). The scattering patterns revealed the formation of either a random periodic or a lamellar phase when 10% (w/w) water was added. All formulations exhibited lamellar structures at 20% (w/w) aqueous dilution, of which the layer-to-layer distance increased upon further addition of water. At 40% (w/w) water, a hexagonal or lamellar phase was formed, depending on the geometry of the surfactant. Temperature did not alter the phases formed. Incorporation of the drug UC 781 only slightly enlarged the characteristic dimensions of the liquid crystalline phases. Drug solubility decreased upon aqueous dilution, although 10% (w/w) dilutions of PGDCDC-P80 SMEDDS and PGDCDC-TPGS 1000 SMEDDS revealed a highly increased solubility as compared to the pure formulations. Drug release data revealed that UC 781 release could not be linked to the solubilisation capacity of the SMEDDS, but could be associated with the solubility of UC 781 in the phases formed at water concentrations above 10% (w/w).

  10. Three-dimensional Morphology and X-ray Scattering Structure of Aqueous tert-Butanol Mixtures: A Molecular Dynamics Study

    Indian Academy of Sciences (India)

    SUPREET KAUR; HEMANT K KASHYAP

    2017-01-01

    It is well established that water-alcohol mixtures exhibit anomalous properties at very low as well as at very high alcohol concentrations. Almost all the studies in this regard intend to link these anomalies to the microscopic structural changes as water (or alcohol) concentration increases in the mixture. However, it isimportant to note that the nature of these structural changes could be different at the water- and TBA-rich concentrations. In this article, our goal is to address such structural change overs, if really present, in the mixtures of water and tert-butanol (TBA) by using simulated X-ray scattering structure function, S(q), real space radial and spatial distribution functions and heterogeneity order parameter. By using a judicial partitioning scheme, we show that structural characteristic of pure water is qualitatively retained for XTBA < 0.1. The simulated S(q) peaks at around q=2 and q=2.8 Å⁻¹, which correspond to water oxygen correlations, begin to fade away only after XTBA ≥ 0.1. This is a clear indication of microscopic structural transition at XTBA ≈ 0.1. Beyond XTBA = 0.1, the TBA structural features begin to take over to that of water. The peak at q=1.3 Å⁻¹ which primarily corresponds to nonpolar-nonpolar correlations in pure TBA begin to rise at XTBA ≈ 0.1. However, the pre-peak at around q=0.75 Å⁻¹, which is due to polar-polar and nonpolar-polar correlations in pure TBA, seems to appear at lower q value only at the equi-molar concentration of the mixture. From the solvent cage surrounding the TBA molecules, we observe that while the aggregation of TBA alkyl groups, due to hydrophobic interaction, is maximum at 10% TBA, the intervening hydrogen bonding interactions between water and TBA molecules tend to lower the hydrophobic interactions between the alkyl groups of alcohol with increasing concentration of TBA. In addition to this, we also observe dimers and small clusters of water molecules in the TBA-rich regime. The

  11. Hydrogen bond breaking in aqueous solutions near the critical point

    Science.gov (United States)

    Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

    2001-01-01

    The nature of water-anion bonding is examined using X-ray absorption fine structure spectroscopy on a 1mZnBr2/6m NaBr aqueous solution, to near critical conditions. Analyses show that upon heating the solution from 25??C to 500??C, a 63% reduction of waters occurs in the solvation shell of ZnBr42-, which is the predominant complex at all pressure-temperature conditions investigated. A similar reduction in the hydration shell of waters in the Br- aqua ion was found. Our results indicate that the water-anion and water-water bond breaking mechanisms occurring at high temperatures are essentially the same. This is consistent with the hydration waters being weakly hydrogen bonded to halide anions in electrolyte solutions. ?? 2001 Elsevier Science B.V.

  12. The solvent shell structure of aqueous iodide: X-ray absorption spectroscopy and classical, hybrid QM/MM and full quantum molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pham, V.T. [Ecole Polytechnique Federale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland); Tavernelli, I. [Ecole Polytechnique Federale de Lausanne, Laboratoire de chimie et biochimie computationnelles, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland); Milne, C.J.; van der Veen, R.M. [Ecole Polytechnique Federale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland); D' Angelo, P. [Dipartimento di Chimica, Universita di Roma ' La Sapienza' , Ple A. Moro 5, 00185 Roma (Italy); Bressler, Ch. [Ecole Polytechnique Federale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland); Chergui, M., E-mail: Majed.Chergui@epfl.ch [Ecole Polytechnique Federale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland)

    2010-05-25

    Graphical abstract: The L{sub 3}-edge EXAFS spectra of aqueous iodide are compared to classical, QM/MM and DFT-based molecular dynamics simulations. The QM/MM simulations reproduce best the experimental data. An anisotropy of the solvation shell is also identified. - Abstract: The L{sub 3} X-ray absorption spectrum of aqueous iodide is reported, and its EXAFS is compared to theoretical spectra reconstructed from the radial distribution function of the iodide hydration obtained from classical, hybrid Quantum Mechanics Molecular Mechanics, (QM/MM) and full quantum (density functional theory, DFT) molecular dynamics simulations. Since EXAFS is mainly sensitive to short distances around the iodide ion, it is a direct probe of the local solvation structure. The comparison shows that QM/MM simulations deliver a satisfactory description of the EXAFS signal, while nonpolarizable classical simulations are somewhat less satisfactory and DFT-based simulations perform poorly. We also identify a weak anisotropy of the water solvation shell around iodide, which may be of importance in electron photoejection experiments.

  13. Solution of Ge(111)-(4x4)-Ag structure using direct methods applied to X-ray diffraction data

    DEFF Research Database (Denmark)

    Collazo-Davila, C.; Grozea, D.; Marks, L.D.

    1998-01-01

    A structure model for the Ge(111)-(4 x 4)-Ag surface is proposed. The model was derived by applying direct methods to surface X-ray diffraction data. It is a missing top layer reconstruction with six Ag atoms placed on Ge substitutional sites in one triangular subunit of the surface unit cell...

  14. Analytical Instrument of X-ray Fluorescence Determine Concentration of U and Pu in Organic Solution at the Same Time

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    An instrument is developed to measure the concentration of U, Pu and the intensity of gamma ray in samples of 1AP organic phase at the same time. The Ag cold cathode is used to excite L series X-ray fluorescence of U and Pu. The Si-pin detector is

  15. X-Ray Detector-on-Plastic with High Sensitivity Using Low Cost, Solution-Processed Organic Photodiodes

    NARCIS (Netherlands)

    Gelinck, G.H.; Kumar, A.; Moet, D.; Steen, J.L.P.J. van der; Breemen, A.J.J.M. van; Shanmugam, S.; Langen, A.; Gilot, J.; Groen, W.A.; Andriessen, H.A.J.M.; Simon, M.; Ruetten, W.; Douglas, A.U.; Raaijmakers, R.; Malinowski, P.E.; Myny, K.

    2016-01-01

    We made and characterized an X-ray detector on a 25-ìm-thick plastic substrate that is capable of medicalgrade performance. As an indirect conversion flat panel detector, it combined a standard scintillator with an organic photodetector (OPD) layer and oxide thin-film transistor backplane. Using sol

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

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lingling [Stanford Univ., CA (United States)

    1996-04-01

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

  17. Topical Review: Molecular reaction and solvation visualized by time-resolved X-ray solution scattering: Structure, dynamics, and their solvent dependence

    Directory of Open Access Journals (Sweden)

    Kyung Hwan Kim

    2014-01-01

    Full Text Available Time-resolved X-ray solution scattering is sensitive to global molecular structure and can track the dynamics of chemical reactions. In this article, we review our recent studies on triiodide ion (I3– and molecular iodine (I2 in solution. For I3–, we elucidated the excitation wavelength-dependent photochemistry and the solvent-dependent ground-state structure. For I2, by combining time-slicing scheme and deconvolution data analysis, we mapped out the progression of geminate recombination and the associated structural change in the solvent cage. With the aid of X-ray free electron lasers, even clearer observation of ultrafast chemical events will be made possible in the near future.

  18. X-ray absorption spectra of nucleotides (AMP, GMP, and CMP) in liquid water solutions near the nitrogen K-edge

    Science.gov (United States)

    Ukai, Masatoshi; Yokoya, Akinari; Fujii, Kentaro; Saitoh, Yuji

    2010-07-01

    The X-ray absorption of nucleotides (adenosine-5'-monophosphate, guanosine 5'-monophosphate, and cytidine 5'-monophosphate) are measured in both water solutions and thin solid films at X-ray energies near the nitrogen K-edge in the 'water-window' region. Each spectrum corresponds to the selective excitation of a nucleobase site in a nucleotide, and thus has features similar to the spectrum of the corresponding nucleobase. An additional new peak in the energy region of the nitrogen 1s → π* resonance is observed for each nucleotide. No significant difference between the water solutions and thin solid films is found, which might be attributable to the hydrophobic properties of a nucleobase in a nucleotide.

  19. Evidence for lattice strain and non-ideal behaviour in the (La1-xEux)PO4 solid solution from X-ray diffraction and vibrational spectroscopy

    Science.gov (United States)

    Geisler, Thorsten; Popa, Karin; Konings, Rudy

    2016-06-01

    The monazite-type solid solution of LaPO_4 and EuPO_4 has been studied by X-ray diffraction, infrared (IR) and Raman spectroscopic techniques. A substantial excess molar volume has been derived from the X-ray data, and the Raman and IR spectra show band broadening typical for mixing of cations of different size on the cation sublattice. The IR spectra were interpreted by the autocorrelation method and the excess autocorrelation parameter Δ{corr}^{ex} shows clear deviation from ideal solution behaviour, similar to the observed broadening of the Raman bands. The results can be interpreted in terms of local lattice strains resulting from the ion size effects of substitution of La^{3+} by Eu^{3+}, and correlate very well with calorimetric measurements of the excess enthalpy that was previously measured.

  20. Abdominal x-ray

    Science.gov (United States)

    ... are, or may be, pregnant. Alternative Names Abdominal film; X-ray - abdomen; Flat plate; KUB x-ray ... Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also ...

  1. Extremity x-ray

    Science.gov (United States)

    ... degenerative) Bone tumor Broken bone (fracture) Dislocated bone Osteomyelitis (infection) Arthritis Other conditions for which the test ... Bone tumor Bone x-ray Broken bone Clubfoot Osteomyelitis X-ray Review Date 7/3/2016 Updated ...

  2. Probing ion-specific effects on aqueous acetate solutions: Ion pairing versus water structure modifications

    Directory of Open Access Journals (Sweden)

    Tristan Petit

    2014-05-01

    Full Text Available The effect of monovalent cations (Li+, K+, NH4+, Na+ on the water structure in aqueous chloride and acetate solutions was characterized by oxygen K-edge X-ray absorption spectroscopy (XAS, X-ray emission spectroscopy, and resonant inelastic X-ray scattering (RIXS of a liquid microjet. We show ion- and counterion dependent effects on the emission spectra of the oxygen K-edge, which we attribute to modifications of the hydrogen bond network of water. For acetates, ion pairing with carboxylates was also probed selectively by XAS and RIXS. We correlate our experimental results to speciation data and to the salting-out properties of the cations.

  3. Removal of phosphate from aqueous solution with blast furnace slag.

    Science.gov (United States)

    Oguz, Ensar

    2004-10-18

    Blast furnace slag was used to remove phosphate from aqueous solutions. The influence of pH, temperature, agitation rate, and blast furnace slag dosage on phosphate removal was investigated by conducting a series of batch adsorption experiments. In addition, the yield and mechanisms of phosphate removal were explained on the basis of the results of X-ray spectroscopy, measurements of zeta potential of particles, specific surface area, and images of scanning electron microscopy (SEM) of the particles before and after adsorption. The specific surface area of the blast furnace slag was 0.4m(2)g(-1). The removal of phosphate predominantly has taken place by a precipitation mechanism and weak physical interactions between the surface of adsorbent and the metallic salts of phosphate. In this study, phosphate removal in excess of 99% was obtained, and it was concluded that blast furnace slag is an efficient adsorbent for the removal of phosphate from solution.

  4. X-ray investigation of gene-engineered human insulin crystallized from a solution containing polysialic acid

    Science.gov (United States)

    Timofeev, V. I.; Chuprov-Netochin, R. N.; Samigina, V. R.; Bezuglov, V. V.; Miroshnikov, K. A.; Kuranova, I. P.

    2010-01-01

    Attempts to crystallize the noncovalent complex of recombinant human insulin with polysialic acid were carried out under normal and microgravity conditions. Both crystal types belonged to the same space group, I213, with unit-cell parameters a = b = c = 77.365 Å, α = β = γ = 90.00°. The reported space group and unit-cell parameters are almost identical to those of cubic insulin reported in the PDB. The results of X-ray studies confirmed that the crystals obtained were cubic insulin crystals and that they contained no polysialic acid or its fragments. Electron-density maps were calculated using X-ray diffraction sets from earth-grown and microgravity-grown crystals and the three-dimensional structure of the insulin molecule was determined and refined. The conformation and secondary-structural elements of the insulin molecule in different crystal forms were compared. PMID:20208155

  5. Intermolecular bonding of hemin in solution and in solid state probed by N K-edge X-ray spectroscopies.

    Science.gov (United States)

    Golnak, Ronny; Xiao, Jie; Atak, Kaan; Stevens, Joanna S; Gainar, Adrian; Schroeder, Sven L M; Aziz, Emad F

    2015-11-21

    X-ray absorption/emission spectroscopy (XAS/XES) at the N K-edge of iron protoporphyrin IX chloride (FePPIX-Cl, or hemin) has been carried out for dissolved monomers in DMSO, dimers in water and for the solid state. This sequence of samples permits identification of characteristic spectral features associated with the hemin intermolecular bonding. These characteristic features are further analyzed and understood at the molecular orbital (MO) level based on the DFT calculations.

  6. X-Ray Supernovae

    CERN Document Server

    Immler, S; Immler, Stefan; Lewin, Walter H.G.

    2002-01-01

    We present a review of X-ray observations of supernovae (SNe). By observing the (~0.1--100 keV) X-ray emission from young SNe, physical key parameters such as the circumstellar matter (CSM) density, mass-loss rate of the progenitor and temperature of the outgoing and reverse shock can be derived as a function of time. Despite intensive search over the last ~25 years, only 15 SNe have been detected in X-rays. We review the individual X-ray observations of these SNe and discuss their implications as to our understanding of the physical processes giving rise to the X-ray emission.

  7. Zinc chloride aqueous solution as a solvent for starch.

    Science.gov (United States)

    Lin, Meiying; Shang, Xiaoqin; Liu, Peng; Xie, Fengwei; Chen, Xiaodong; Sun, Yongyi; Wan, Junyan

    2016-01-20

    It is important to obtain starch-based homogeneous systems for starch modification. Regarding this, an important key point is to find cheap, low-cost and low-toxicity solvents to allow complete dissolution of starch and its easy regeneration. This study reveals that a ZnCl2 aqueous solution is a good non-derivatizing solvent for starch at 50 °C, and can completely dissolve starch granules. The possible formation of a "zinc-starch complex" might account for the dissolution; and the degradation of starch, which was caused by the H(+) inZnCl2 aqueous solution, could not contribute to full dissolution. From polarized light microscopic observation combined with the solution turbidity results, it was found that the lowest ZnCl2 concentration for full dissolution was 29.6 wt.% at 50 °C, with the dissolving time being 4h. Using Fourier-transform infrared (FTIR), solid state (13)C nuclear magnetic resonance (NMR), and X-ray diffraction (XRD), it was revealed that ZnCl2 solution had no chemical reaction with starch glucosides, but only weakened starch hydrogen bonding and converted the crystalline regions to amorphous regions. In addition, as shown by intrinsic viscosity and thermogravimetric analysis (TGA), ZnCl2 solution caused degradation of starch macromolecules, which was more serious with a higher concentration of ZnCl2 solution.

  8. Butterfly Deformation Modes in a Photoexcited Pyrazolate-Bridged Pt Complex Measured by Time-Resolved X-Ray Scattering in Solution

    DEFF Research Database (Denmark)

    Haldrup, Kristoffer; Dohn, Asmus Ougaard; Shelby, Megan L.

    2016-01-01

    the monochromatic X-ray pulses at Beamline 11IDD of the Advanced Photon Source. The excited-state structural analysis of 1 was performed based on the results from both transient WAXS measurements and density functional theory calculations to shed light on the primary structural changes in its triplet metal......Pyrazolate-bridged dinuclear Pt(II) complexes represent a series of molecules with tunable absorption and emission properties that can be directly modulated by structural factors, such as the Pt-Pt distance. However, direct experimental information regarding the structure of the emissive triplet...... excited state has remained scarce. Using time-resolved wide-angle X-ray scattering (WAXS), the excited triplet state molecular structure of [Pt(ppy)(μ-t-Bu2pz)]2 (ppy = 2-phenylpyridine; t-Bu2pz = 3,5-di-tert-butylpyrazolate), complex 1, was obtained in a dilute (0.5 mM) toluene solution utilizing...

  9. Solution Structures of Highly Active Molecular Ir Water-Oxidation Catalysts from Density Functional Theory Combined with High-Energy X-ray Scattering and EXAFS Spectroscopy.

    Science.gov (United States)

    Yang, Ke R; Matula, Adam J; Kwon, Gihan; Hong, Jiyun; Sheehan, Stafford W; Thomsen, Julianne M; Brudvig, Gary W; Crabtree, Robert H; Tiede, David M; Chen, Lin X; Batista, Victor S

    2016-05-04

    The solution structures of highly active Ir water-oxidation catalysts are elucidated by combining density functional theory, high-energy X-ray scattering (HEXS), and extended X-ray absorption fine structure (EXAFS) spectroscopy. We find that the catalysts are Ir dimers with mono-μ-O cores and terminal anionic ligands, generated in situ through partial oxidation of a common catalyst precursor. The proposed structures are supported by (1)H and (17)O NMR, EPR, resonance Raman and UV-vis spectra, electrophoresis, etc. Our findings are particularly valuable to understand the mechanism of water oxidation by highly reactive Ir catalysts. Importantly, our DFT-EXAFS-HEXS methodology provides a new in situ technique for characterization of active species in catalytic systems.

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

    Directory of Open Access Journals (Sweden)

    Yifeng Yun

    2015-03-01

    Full Text Available 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

  11. Porous Methyltrimethoxysilane Coated Nanoscale-Hydroxyapatite for Removing Lead Ions from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    C. S. Ciobanu

    2014-01-01

    Full Text Available The aim of this study was to synthetize new porous nanoparticles based on methyltrimethoxysilane coated hydroxyapatite (MTHAp for lead removal form aqueous solutions. The morphological and compositional analysis of MTHAp were investigated by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and scanning electron microscopy (SEM equipped with an energy dispersive X-ray spectrometer (EDS. Removal experiments of Pb2+ ions were carried out in aqueous solutions with controlled concentration of Pb2+ at a fixed pH value of 3 and 5 respectively. After the removal experiment of Pb2+ ions from solutions, porous hydroxyapatite nanoparticles were transformed into PbMTHAp_3 and PbMTHAp_5 via the adsorption of Pb2+ ions followed by a cation exchange reaction. The X-ray diffraction spectra of PbMTHAp_3 and PbMTHAp_5 revealed that the powders, after removal of the Pb2+ ions, were a mixture of Ca2.5Pb7.5(PO46(OH2, Pb2Ca4(PO42(SiO4, and Ca10(PO46(OH2. Our results demonstrate that the porous hydroxyapatite nanoparticles can be used as an adsorbent for removing Pb2+ ions from aqueous solutions.

  12. A new method for preparation of magnetite from iron oxyhydroxide or iron oxide and ferrous salt in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Kahani, S.A. [Department of Chemistry, Faculty of Science, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of)], E-mail: Kahani@kashanu.ac.ir; Jafari, M. [Department of Chemistry, Faculty of Science, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of)

    2009-07-15

    In this study, a new method is proposed for the preparation of Fe{sub 3}O{sub 4} from iron oxyhydroxides (goethite, akaganeite, lepidocrocite, feroxyhyte and ferrihydrite) or iron oxide (hematite) and ferrous salt in aqueous solution. The product is magnetite with various particle sizes. Products are characterized by X-ray powder diffraction, IR spectra and vibrating sample magnetometery.

  13. Preparation of nanosized barium zirconate powder by precipitation in aqueous solution

    OpenAIRE

    Boschini, Frédéric; Guillaume, Bernard; Rulmont, André; Cloots, Rudi

    2004-01-01

    Several ways were explored to synthesize barium zirconate by soft chemistry methods in aqueous solution. In the first method the synthesis of barium zirconate was initiated by urea decomposition, through an homogeneous precipitation of barium and zirconium salts followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that a...

  14. Combined operando X-ray diffraction-electrochemical impedance spectroscopy detecting solid solution reactions of LiFePO4 in batteries.

    Science.gov (United States)

    Hess, Michael; Sasaki, Tsuyoshi; Villevieille, Claire; Novák, Petr

    2015-09-08

    Lithium-ion batteries are widely used for portable applications today; however, often suffer from limited recharge rates. One reason for such limitation can be a reduced active surface area during phase separation. Here we report a technique combining high-resolution operando synchrotron X-ray diffraction coupled with electrochemical impedance spectroscopy to directly track non-equilibrium intermediate phases in lithium-ion battery materials. LiFePO4, for example, is known to undergo phase separation when cycled under low-current-density conditions. However, operando X-ray diffraction under ultra-high-rate alternating current and direct current excitation reveal a continuous but current-dependent, solid solution reaction between LiFePO4 and FePO4 which is consistent with previous experiments and calculations. In addition, the formation of a preferred phase with a composition similar to the eutectoid composition, Li0.625FePO4, is evident. Even at a low rate of 0.1C, ∼20% of the X-ray diffractogram can be attributed to non-equilibrium phases, which changes our understanding of the intercalation dynamics in LiFePO4.

  15. Combined operando X-ray diffraction-electrochemical impedance spectroscopy detecting solid solution reactions of LiFePO4 in batteries

    Science.gov (United States)

    Hess, Michael; Sasaki, Tsuyoshi; Villevieille, Claire; Novák, Petr

    2015-09-01

    Lithium-ion batteries are widely used for portable applications today; however, often suffer from limited recharge rates. One reason for such limitation can be a reduced active surface area during phase separation. Here we report a technique combining high-resolution operando synchrotron X-ray diffraction coupled with electrochemical impedance spectroscopy to directly track non-equilibrium intermediate phases in lithium-ion battery materials. LiFePO4, for example, is known to undergo phase separation when cycled under low-current-density conditions. However, operando X-ray diffraction under ultra-high-rate alternating current and direct current excitation reveal a continuous but current-dependent, solid solution reaction between LiFePO4 and FePO4 which is consistent with previous experiments and calculations. In addition, the formation of a preferred phase with a composition similar to the eutectoid composition, Li0.625FePO4, is evident. Even at a low rate of 0.1C, ~20% of the X-ray diffractogram can be attributed to non-equilibrium phases, which changes our understanding of the intercalation dynamics in LiFePO4.

  16. Combined operando X-ray diffraction–electrochemical impedance spectroscopy detecting solid solution reactions of LiFePO4 in batteries

    Science.gov (United States)

    Hess, Michael; Sasaki, Tsuyoshi; Villevieille, Claire; Novák, Petr

    2015-01-01

    Lithium-ion batteries are widely used for portable applications today; however, often suffer from limited recharge rates. One reason for such limitation can be a reduced active surface area during phase separation. Here we report a technique combining high-resolution operando synchrotron X-ray diffraction coupled with electrochemical impedance spectroscopy to directly track non-equilibrium intermediate phases in lithium-ion battery materials. LiFePO4, for example, is known to undergo phase separation when cycled under low-current-density conditions. However, operando X-ray diffraction under ultra-high-rate alternating current and direct current excitation reveal a continuous but current-dependent, solid solution reaction between LiFePO4 and FePO4 which is consistent with previous experiments and calculations. In addition, the formation of a preferred phase with a composition similar to the eutectoid composition, Li0.625FePO4, is evident. Even at a low rate of 0.1C, ∼20% of the X-ray diffractogram can be attributed to non-equilibrium phases, which changes our understanding of the intercalation dynamics in LiFePO4. PMID:26345306

  17. X-Ray Polarimetry

    CERN Document Server

    Kaaret, Philip

    2014-01-01

    We review the basic principles of X-ray polarimetry and current detector technologies based on the photoelectric effect, Bragg reflection, and Compton scattering. Recent technological advances in high-spatial-resolution gas-filled X-ray detectors have enabled efficient polarimeters exploiting the photoelectric effect that hold great scientific promise for X-ray polarimetry in the 2-10 keV band. Advances in the fabrication of multilayer optics have made feasible the construction of broad-band soft X-ray polarimeters based on Bragg reflection. Developments in scintillator and solid-state hard X-ray detectors facilitate construction of both modular, large area Compton scattering polarimeters and compact devices suitable for use with focusing X-ray telescopes.

  18. Microfluidic synthesis of monodisperse Cu nanoparticles in aqueous solution.

    Science.gov (United States)

    Ke, Te; Zeng, Xiao-Fei; Wang, Jie-Xin; Le, Yuan; Chu, Guang-Wen; Chen, Jian-Feng; Shao, Lei

    2011-06-01

    The continuous production of Cu nanoparticles with a particle size of 2-5 nm was conducted by sodium borohydride reduction of copper sulfate in aqueous solution in a tube-in-tube microchannel reactor (TMR), which consists of an inner tube and an outer tube with the reaction performed in the annular microchannel between these two tubes. The as-prepared Cu nanoparticles were compared with those obtained by a conventional batch synthesis process by using transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis spectroscopy. Due to the highly intensified micromixing effects in the TMR, Cu nanoparticles prepared by this route exhibits a smaller particle size, narrower size distribution and better stability in air. The TMR shows an excellent ability of preparing high-quality Cu nanoparticles in mild conditions. In addition, with the unique microchannel structure, the throughput capability of the TMR for the production of Cu nanoparticles is up to several liters per minute.

  19. High performance x-ray imaging detectors on foil using solution-processed organic photodiodes with extremely low dark leakage current (Presentation Recording)

    Science.gov (United States)

    Kumar, Abhishek; Moet, Date; van der Steen, Jan Laurens; van Breemen, Albert; Shanmugam, Santhosh; Gilot, Jan; Andriessen, Ronn; Simon, Matthias; Ruetten, Walter; Douglas, Alexander; Raaijmakers, Rob; Malinowski, Pawel E.; Myny, Kris; Gelinck, Gerwin

    2015-10-01

    High performance X-ray imaging detectors on foil using solution-processed organic photodiodes with extremely low dark leakage current Abhishek Kumara, Date Moeta, Albert van Breemena, Santhosh Shanmugama, Jan-Laurens van der Steena, Jan Gilota, Ronn Andriessena, Matthias Simonb, Walter Ruettenb, Alexander U. Douglasb, Rob Raaijmakersc, Pawel E. Malinowskid, Kris Mynyd and Gerwin H. Gelincka,e a. Holst Centre/TNO, High Tech Campus 31, Eindhoven 5656 AE, The Netherlands b. Philips Research, High Tech Campus 34, 5656 AE Eindhoven, The Netherlands c. Philips Healthcare, Veenpluis 6-8, 5684 PC Best, The Netherlands d. Department of Large Area Electronics, imec vzw, Kapeldreef 75, Leuven B3001, Belgium e. Applied Physics Department, TU Eindhoven, Eindhoven, The Netherlands We demonstrate high performance X-ray imaging detectors on foil suitable for medical grade X-ray imaging applications. The detectors are based on solution-processed organic photodiodes forming bulk-heterojunctions from photovoltaic donor and acceptor blend. The organic photodiodes are deposited using an industrially compatible slot die coating technique with end of line processing temperature below 100°C. These photodiodes have extremely low dark leakage current density of 10-7 mA/cm2 at -2V bias with very high yield and have peak absorption around 550 nm wavelength. We combine these organic photodiodes with high mobility metal oxide semiconductor based thin film transistor arrays with high pixel resolution of 200ppi on thin plastic substrate. When combined with a typical CsI(TI) scintillator material on top, they are well suited for low dose X-ray imaging applications. The optical crosstalk is insignificant upto resolution of 200 ppi despite the fact that the photodiode layer is one continuous layer and is non-pixelated. Low processing temperatures are another key advantage since they can be fabricated on plastic substrate. This implies that we can make X-ray detectors on flexible foil. Those

  20. Semi-rigid solution structures of heparin by constrained X-ray scattering modelling: new insight into heparin-protein complexes.

    Science.gov (United States)

    Khan, Sanaullah; Gor, Jayesh; Mulloy, Barbara; Perkins, Stephen J

    2010-01-22

    The anionic polysaccharides heparin and heparan sulphate play essential roles in the regulation of many physiological processes. Heparin is often used as an analogue for heparan sulphate. Despite knowledge of an NMR solution structure and 19 crystal structures of heparin-protein complexes for short heparin fragments, no structures for larger heparin fragments have been reported up to now. Here, we show that solution structures for six purified heparin fragments dp6-dp36 (where dp stands for degree of polymerisation) can be determined by a combination of analytical ultracentrifugation, synchrotron X-ray scattering, and constrained modelling. Analytical ultracentrifugation velocity data for dp6-dp36 showed sedimentation coefficients that increased linearly from 1.09 S to 1.84 S with size. X-ray scattering of dp6-dp36 gave radii of gyration R(G) that ranged from 1.33 nm to 3.12 nm and maximum lengths that ranged from 3.0 nm to 12.3 nm. The higher resolution of X-ray scattering revealed an increased bending of heparin with increased size. Constrained molecular modelling of 5000 randomised heparin conformers resulted in 9-15 best-fit structures for each of dp18, dp24, dp30, and dp36 that indicated flexibility and the presence of short linear segments in mildly bent structures. Comparisons of these solution structures with crystal structures of heparin-protein complexes revealed similar ranges of phi (phi) and psi (psi) angles between iduronate and glucosamine rings. We conclude that heparin in solution has a semi-rigid and extended conformation that is preformed for its optimal binding to protein targets without major conformational changes.

  1. Removal of zirconium from aqueous solution by modified clinoptilolite

    Energy Technology Data Exchange (ETDEWEB)

    Faghihian, H., E-mail: h.faghih@sci.ui.ac.ir [Department of Chemistry, University of Isfahan, 81746-73441, Isfahan (Iran, Islamic Republic of); Kabiri-Tadi, M. [Department of Chemistry, University of Isfahan, 81746-73441, Isfahan (Iran, Islamic Republic of)

    2010-06-15

    Adsorptive behavior of natural clinoptilolite was assessed for the removal of zirconium from aqueous solutions. Natural zeolite was characterized by X-ray diffraction, X-ray fluorescence, thermal methods of analysis and FTIR. The zeolite sample composed mainly of clinoptilolite and presented a cation exchange capacity of 1.46 meq g{sup -1}. K, Na and Ca-exchanged forms of zeolite were prepared and their sorption capacities for removal of zirconium from aqueous solutions were determined. The effects of relevant parameters, including initial concentration, contact time, temperature and initial pH on the removal efficiency were investigated in batch studies. The pH strongly influenced zirconium adsorption capacity and maximal capacity was obtained at pH 1.0. The maximum removal efficiency obtained at 40 deg. C and equilibration time of 24 h on the Ca-exchanged form. Kinetics and isotherm of adsorption were also studied. The pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion models were used to describe the kinetic data. The pseudo-second-order kinetic model provided excellent kinetic data fitting (R{sup 2} > 0.998) with rate constant of 1.60 x 10{sup -1}, 1.96 x 10{sup -1}, 2.45 x 10{sup -1} and 2.02 x 10{sup -1} g mmol{sup -1} min{sup -1} respectively for Na, K, Ca-exchanged forms and natural clinoptilolite. The Langmuir and Freundlich models were applied to describe the equilibrium isotherms for zirconium uptake and the Langmuir model agrees very well with experimental data. Thermodynamic parameters were determined and are discussed.

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

    KAUST Repository

    Dorin, Rachel Mika

    2012-05-15

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

  3. BioSAXS Sample Changer: a robotic sample changer for rapid and reliable high-throughput X-ray solution scattering experiments

    Energy Technology Data Exchange (ETDEWEB)

    Round, Adam, E-mail: around@embl.fr; Felisaz, Franck [European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble (France); Université Grenoble Alpes–EMBL–CNRS, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble (France); Fodinger, Lukas; Gobbo, Alexandre [European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble (France); Huet, Julien [European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble (France); Université Grenoble Alpes–EMBL–CNRS, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble (France); Villard, Cyril [European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble (France); Blanchet, Clement E., E-mail: around@embl.fr [EMBL c/o DESY, Notkestrasse 85, 22603 Hamburg (Germany); Pernot, Petra; McSweeney, Sean [ESRF, 6 Rue Jules Horowitz, 38000 Grenoble (France); Roessle, Manfred; Svergun, Dmitri I. [EMBL c/o DESY, Notkestrasse 85, 22603 Hamburg (Germany); Cipriani, Florent, E-mail: around@embl.fr [European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble (France); Université Grenoble Alpes–EMBL–CNRS, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble (France)

    2015-01-01

    A robotic sample changer for solution X-ray scattering experiments optimized for speed and to use the minimum amount of material has been developed. This system is now in routine use at three high-brilliance European synchrotron sites, each capable of several hundred measurements per day. Small-angle X-ray scattering (SAXS) of macromolecules in solution is in increasing demand by an ever more diverse research community, both academic and industrial. To better serve user needs, and to allow automated and high-throughput operation, a sample changer (BioSAXS Sample Changer) that is able to perform unattended measurements of up to several hundred samples per day has been developed. The Sample Changer is able to handle and expose sample volumes of down to 5 µl with a measurement/cleaning cycle of under 1 min. The samples are stored in standard 96-well plates and the data are collected in a vacuum-mounted capillary with automated positioning of the solution in the X-ray beam. Fast and efficient capillary cleaning avoids cross-contamination and ensures reproducibility of the measurements. Independent temperature control for the well storage and for the measurement capillary allows the samples to be kept cool while still collecting data at physiological temperatures. The Sample Changer has been installed at three major third-generation synchrotrons: on the BM29 beamline at the European Synchrotron Radiation Facility (ESRF), the P12 beamline at the PETRA-III synchrotron (EMBL@PETRA-III) and the I22/B21 beamlines at Diamond Light Source, with the latter being the first commercial unit supplied by Bruker ASC.

  4. High Resolution X-ray CMT Imaging of Supercritical CO2 in Porous Media: Experimental Challenges, Solutions, and Results

    Science.gov (United States)

    Herring, A. L.; Andersson, L.; Newell, D. L.; Carey, J. W.; Wildenschild, D.

    2013-12-01

    Geologic carbon dioxide (CO2) sequestration has been proposed as a climate change mitigation strategy to limit emissions of CO2 to the atmosphere from large fossil-fuel burning CO2 point sources; however, there are concerns associated with the long-term stability of a mobile subsurface CO2 plume. Capillary trapping of supercritical CO2 (scCO2), wherein the CO2 is held within the pore structure of the geologic matrix by capillary forces, is a more secure form of subsurface storage than structural trapping, which relies on an impermeable caprock to contain the buoyant CO2 plume. To understand the multiphase physics of CO2 transport, and to subsequently produce quantitative estimates of potential CO2 capillary trapping, it is necessary to study field, core, and pore-scale processes. X-ray computed microtomography (x-ray CMT) allows for three-dimensional (3D) in-situ visualization of fluid phases within and the physical structure of a porous medium at the pore-scale. We have designed and built a mobile experimental set-up capable of running at pressures up to 2000 PSI and temperatures up to 50°C, made with materials that are compatible with corrosive fluids. Our experimental procedure includes pressurizing, mixing, and separating fluids; and subsequently running immiscible drainage and imbibition flow experiments with brine and supercritical CO2. With this set-up and procedure, we successfully conducted a brine-scCO2 drainage experiment in Bentheimer sandstone at 1200 PSI and 36°C, and confirmed and quantified CO2 flow in the sandstone core via synchrotron-based x-ray CMT with a resolution of 4.65 μm at the Advanced Photon Source at Argonne National Laboratory. We have proven that we can observe, on a pore-scale basis, the movement of supercritical CO2 within a porous media. The properties of supercritical CO2 (e.g. viscosity, density, interfacial tension and solubility in brine) vary significantly with changes in pressure and temperature; consequently, precise

  5. Sono-electrochemical recovery of metal ions from their aqueous solutions.

    Science.gov (United States)

    Dong, Bingfeng; Fishgold, Asher; Lee, Paul; Runge, Keith; Deymier, Pierre; Keswani, Manish

    2016-11-15

    Metal recovery from aqueous waste streams is an important goal for recycling, agriculture and mining industries. The development of more effective methods of recovery have been of increasing interest. The most common methods for metal recovery include precipitation, electrochemical, ion exchange, flocculation/coagulation and filtration. In the current work, a sono-electrochemical technique employing sound field at megasonic frequency (500kHz or 1MHz) in conjunction with electrochemistry is evaluated for enhanced recovery of selected metal ions (palladium, lead and gallium) with different redox potentials from their aqueous solutions. The surface morphology and elemental composition of the metal deposits were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The percent recovery was found to depend on the type of metal ion and the megasonic frequency used. Palladium was recovered in its metal form, while lead and gallium were oxidized during or after the recovery process.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-06

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

  7. On the nature of lithium biphenyl in ethereal solvents. A critical analysis unifying DFT calculations, physicochemical data in solution, and a X-ray structure.

    Science.gov (United States)

    de la Viuda, Mónica; Yus, Miguel; Guijarro, Albert

    2011-12-15

    The lithium ion is an important type of electrolyte that has technological applications in the manufacture of lithium ion cells; therefore, a better understanding of the nature of its solutions is desirable. When associated to the radical anion of biphenyl in an organic solvent, it forms conducting solutions comparable to strong electrolytes such as lithium perchlorate. We have studied the lithium biphenyl solution in dimethoxyethane using DFT calculations. The nature of these ionic solutions is described in terms of a dynamic equilibrium between different types of ionic associations, the composition of which depends on the solvent and the temperature. The X-ray structure of [Li(+)·4C(5)H(10)O][C(12)H(10)(•-)], a solvent-separated ion pair of lithium biphenyl complexed with tetrahydropyran, is reported. Its main structural characteristics coincide with the calculated one, which we think is the dominant species at room temperature, in agreement with the available physicochemical data.

  8. [Small-angle x-ray and sedimentation studies on alpha-haemocyanin H. pomatia (halve molecules) in glycerol and sucrose solutions (author's transl)].

    Science.gov (United States)

    Berger, J; Pilz, I; Witters, R; Lontie, R

    1976-01-01

    The alpha-haemocyanin molecules of Helix pomatia were decomposed into halves and studied in solution by small-angle X-ray scattering. The following parameters of the molecule could be obtained: radius of gyration, volume, molecular weight, overall shape and dimensions of the molecule. With small-angle X-ray scattering fluctuations of the electron density within the protein cause parasitic scattering at larger angles. According to Stuhrmann and Kirste it is possible to eliminate it mathematically by varying the electron density of the buffer. For this purpose different quantities of glycerol respectively saccharose were added to the solvent to study the scattering of alpha-haemocyanin halves in solvents of varied electron density. The change of the isopotential specific volume of haemocyanin and the strong increase of the statistical errors of its scattering by decreasing of the excess scattering of solution over solvent per unit volume did not allow an application of the method of Stuhrmann and Kirste. The data obtained for alpha-haemocanin halves in different solvents are given. Besides also the sedimentation of the alpha-haemocyanin halves were studied in solutions containing varied amounts of glycerol and saccharose. An attempt was made to calculate the change of the partial specific volume of haemocyanin by adding glycerol or saccharose.

  9. Dental x-rays

    Science.gov (United States)

    ... X-rays are a form of high energy electromagnetic radiation. The x-rays penetrate the body to form ... for detecting cavities, unless the decay is very advanced and deep. Many ... The amount of radiation given off during the procedure is less than ...

  10. Heterojunction of Zinc Blende/Wurtzite in Zn1-xCdxS Solid Solution for Efficient Solar Hydrogen Generation: X-ray Absorption/Diffraction Approaches.

    Science.gov (United States)

    Hsu, Ying-Ya; Suen, Nian-Tzu; Chang, Chung-Chieh; Hung, Sung-Fu; Chen, Chi-Liang; Chan, Ting-Shan; Dong, Chung-Li; Chan, Chih-Chieh; Chen, San-Yuan; Chen, Hao Ming

    2015-10-14

    In the past decade, inorganic semiconductors have been successfully demonstrated as light absorbers in efficient solar water splitting to generate chemical fuels. Pseudobinary semiconductors Zn1-xCdxS (0≤x≤1) have exhibited a superior photocatalytic reactivity of H2 production from splitting of water by artificial solar irradiation without any metal catalysts. However, most studies had revealed that the extremely high efficiency with an optimal content of Zn1-xCdxS solid solution was determined as a result of elevating the conduction band minimum (CBM) and the width of bandgap. In addition to corresponding band structure and bandgap, the local crystal structure should be taken into account as well to determine its photocatalytic performance. Herein, we demonstrated the correlations between the photocatalytic activity and structural properties that were first studied through synchrotron X-ray diffraction and X-ray absorption spectroscopy. The crystal structure transformed from zinc blende to coexisted phases of major zinc blende and minor wurtzite phases at a critical point. The heterojunction formed by coexistence of zinc blende and wurtzite phases in the Zn1-xCdxS solid solution can significantly improve the separation and migration of photoinduced electron-hole pairs. Besides, X-ray absorption spectra and UV-vis spectra revealed that the bandgap of the Zn0.45Cd0.55S sample extended into the region of visible light because of the incorporation of Cd element in the sample. These results provided a significant progress toward the realization of the photoelectrochemical mechanism in heterojunction between zinc blende and wurtzite phases, which can effectively separate the charge-carriers and further suppress their recombination to enhance the photocatalytic reactivity.

  11. X-Ray Surveys

    CERN Document Server

    Giommi, P; Perri, M

    1998-01-01

    A review of recent developments in the field of X-ray surveys, especially in the hard (2-10 and 5-10 keV) bands, is given. A new detailed comparison between the measurements in the hard band and extrapolations from ROSAT counts, that takes into proper account the observed distribution of spectral slopes, is presented. Direct comparisons between deep ROSAT and BeppoSAX images show that most hard X-ray sources are also detected at soft X-ray energies. This may indicate that heavily cutoff sources, that should not be detectable in the ROSAT band but are expected in large numbers from unified AGN schemes, are in fact detected because of the emerging of either non-nuclear components, or of reflected, or partially transmitted nuclear X-rays. These soft components may complicate the estimation of the soft X-ray luminosity function and cosmological evolution of AGN.

  12. Look fast: Crystallization of conjugated molecules during solution shearing probed in-situ and in real time by X-ray scattering

    KAUST Repository

    Smilgies, Detlef Matthias

    2012-12-20

    High-speed solution shearing, in which a drop of dissolved material is spread by a coating knife onto the substrate, has emerged as a versatile, yet simple coating technique to prepare high-mobility organic thin film transistors. Solution shearing and subsequent drying and crystallization of a thin film of conjugated molecules is probed in situ using microbeam grazing incidence wide-angle X-ray scattering (μGIWAXS). We demonstrate the advantages of this approach to study solution based crystal nucleation and growth, and identify casting parameter combinations to cast highly ordered and laterally aligned molecular thin films. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. BioSAXS Sample Changer: a robotic sample changer for rapid and reliable high-throughput X-ray solution scattering experiments

    Science.gov (United States)

    Round, Adam; Felisaz, Franck; Fodinger, Lukas; Gobbo, Alexandre; Huet, Julien; Villard, Cyril; Blanchet, Clement E.; Pernot, Petra; McSweeney, Sean; Roessle, Manfred; Svergun, Dmitri I.; Cipriani, Florent

    2015-01-01

    Small-angle X-ray scattering (SAXS) of macromolecules in solution is in increasing demand by an ever more diverse research community, both academic and industrial. To better serve user needs, and to allow automated and high-throughput operation, a sample changer (BioSAXS Sample Changer) that is able to perform unattended measurements of up to several hundred samples per day has been developed. The Sample Changer is able to handle and expose sample volumes of down to 5 µl with a measurement/cleaning cycle of under 1 min. The samples are stored in standard 96-well plates and the data are collected in a vacuum-mounted capillary with automated positioning of the solution in the X-ray beam. Fast and efficient capillary cleaning avoids cross-contamination and ensures reproducibility of the measurements. Independent temperature control for the well storage and for the measurement capillary allows the samples to be kept cool while still collecting data at physiological temperatures. The Sample Changer has been installed at three major third-generation synchrotrons: on the BM29 beamline at the European Synchrotron Radiation Facility (ESRF), the P12 beamline at the PETRA-III synchrotron (EMBL@PETRA-III) and the I22/B21 beamlines at Diamond Light Source, with the latter being the first commercial unit supplied by Bruker ASC. PMID:25615861

  14. BioSAXS Sample Changer: a robotic sample changer for rapid and reliable high-throughput X-ray solution scattering experiments.

    Science.gov (United States)

    Round, Adam; Felisaz, Franck; Fodinger, Lukas; Gobbo, Alexandre; Huet, Julien; Villard, Cyril; Blanchet, Clement E; Pernot, Petra; McSweeney, Sean; Roessle, Manfred; Svergun, Dmitri I; Cipriani, Florent

    2015-01-01

    Small-angle X-ray scattering (SAXS) of macromolecules in solution is in increasing demand by an ever more diverse research community, both academic and industrial. To better serve user needs, and to allow automated and high-throughput operation, a sample changer (BioSAXS Sample Changer) that is able to perform unattended measurements of up to several hundred samples per day has been developed. The Sample Changer is able to handle and expose sample volumes of down to 5 µl with a measurement/cleaning cycle of under 1 min. The samples are stored in standard 96-well plates and the data are collected in a vacuum-mounted capillary with automated positioning of the solution in the X-ray beam. Fast and efficient capillary cleaning avoids cross-contamination and ensures reproducibility of the measurements. Independent temperature control for the well storage and for the measurement capillary allows the samples to be kept cool while still collecting data at physiological temperatures. The Sample Changer has been installed at three major third-generation synchrotrons: on the BM29 beamline at the European Synchrotron Radiation Facility (ESRF), the P12 beamline at the PETRA-III synchrotron (EMBL@PETRA-III) and the I22/B21 beamlines at Diamond Light Source, with the latter being the first commercial unit supplied by Bruker ASC.

  15. Femtosecond X-ray solution scattering reveals that bond formation mechanism of a gold trimer complex is independent of excitation wavelength

    Directory of Open Access Journals (Sweden)

    Kyung Hwan Kim

    2016-07-01

    Full Text Available The [Au(CN2−]3 trimer in water experiences a strong van der Waals interaction between the d10 gold atoms due to large relativistic effect and can serve as an excellent model system to study the bond formation process in real time. The trimer in the ground state (S0 exists as a bent structure without the covalent bond between the gold atoms, and upon the laser excitation, one electron in the antibonding orbital goes to the bonding orbital, thereby inducing the formation of a covalent bond between gold atoms. This process has been studied by various time-resolved techniques, and most of the interpretation on the structure and dynamics converge except that the structure of the first intermediate (S1 has been debated due to different interpretations between femtosecond optical spectroscopy and femtosecond X-ray solution scattering. Recently, the excitation wavelength of 267 nm employed in our previous scattering experiment was suggested as the culprit for misinterpretation. Here, we revisited this issue by performing femtosecond X-ray solution scattering with 310 nm excitation and compared the results with our previous study employing 267 nm excitation. The data show that a linear S1 structure is formed within 500 fs regardless of excitation wavelength and the structural dynamics observed at both excitation wavelengths are identical to each other within experimental errors.

  16. X-ray crystallography

    Science.gov (United States)

    2001-01-01

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

  17. Beryllium Chelation by Dicarboxylic Acids in Aqueous Solution.

    Science.gov (United States)

    Schmidt, Michael; Bauer, Andreas; Schmidbaur, Hubert

    1997-05-07

    Maleic and phthalic acids are found to react with Be(OH)(2), generated in situ from BeSO(4)(aq) and Ba(OH)(2)(aq), in aqueous solution at pH 3.0 or 4.4, respectively (25 degrees C), to give solutions containing the complexes (H(2)O)(2)Be[(OOCCH)(2)] (1) and (H(2)O)(2)Be[(OOC)(2)C(6)H(4)] (3). The products can be isolated in high yield and identified by microanalytical data. With 2 equiv of the dicarboxylic acids and the pH adjusted to 5.5 and 5.9, respectively, by addition of ammonia, the bis-chelate complexes [(NH(4))(+)](2){[Be[(OOCCH)(2)](2)}(2)(-) (2) and [(NH(4))(+)](2){Be[(OOC)(2)C(6)H(4)](2)}(2)(-) (4) are obtained, which can also be isolated. The compounds show distinct (9)Be, (1)H, and (13)C resonances in their NMR spectra in aqueous solutions. Layering of an aqueous solution of compound 4 with acetone at ambient temperature leads to the precipitation of single crystals suitable for an X-ray structure determination. This salt (5) was found to contain the bis-chelated dianion {Be[(OOC)(2)C(6)H(4)](2)}(2)(-) with the beryllium atom in the spiro center of two seven-membered rings and an overall geometry approaching closely C(2) symmetry. These anions are associated with two crystallographically independent but structurally similar counterions [MeC(O)CH(2)CMe(2)NH(3)](+), which are the product of a condensation reaction of the ammonium cation with the acetone solvent. In the crystal the ammonium hydrogen atoms of the cations form N-H.O hydrogen bonds with the oxo functions of the dianion.

  18. X-ray lasers

    CERN Document Server

    Elton, Raymond C

    2012-01-01

    The first in its field, this book is both an introduction to x-ray lasers and a how-to guide for specialists. It provides new entrants and others interested in the field with a comprehensive overview and describes useful examples of analysis and experiments as background and guidance for researchers undertaking new laser designs. In one succinct volume, X-Ray Lasers collects the knowledge and experience gained in two decades of x-ray laser development and conveys the exciting challenges and possibilities still to come._Add on for longer version of blurb_M>The reader is first introduced

  19. X-ray photoelectron spectroscopy of oxygen-containing layers formed by a linear potential scan on stepped gold (111) films in aqueous 1 M sulphuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Nieto, Felipe J. [Instituto de Investigaciones Fisicoquimica Teoricas y Aplicadas INIFTA, Universidad Nacional de La Plata, Consejo Nacional de Investigaciones Cientificas y Tecnicas Sucursal 4, Casilla de Correo 16, (1900) La Plata (Argentina); Member of Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (Argentina)], E-mail: rodrini@inifta.unlp.edu.ar; Fachini, Esteban; Cabrera, Carlos R. [Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, P.O. Box 23346, San Juan, 00931-3346 (Puerto Rico); Arvia, Alejandro J. [Instituto de Investigaciones Fisicoquimica Teoricas y Aplicadas INIFTA, Universidad Nacional de La Plata, Consejo Nacional de Investigaciones Cientificas y Tecnicas Sucursal 4, Casilla de Correo 16, (1900) La Plata (Argentina)

    2009-01-01

    X-ray photoelectron spectroscopy (XPS) data of oxygen-containing layers (O-layers) made on stepped gold (111) film electrodes from aqueous 1 M sulphuric acid by single linear potential scans at 0.10 V s{sup -1} and 298 K are reported. The potential scan covered from the open circuit potential to anodic switching potential E{sub as} = 2.50 V versus normal hydrogen electrode (NHE) and holding times at E{sub as} in the range 30-300 s. The anodic charge density q{sub a} determined from the oxidation and reduction voltammetric scan is in the range 0.20 {<=} q{sub a} {<=} 2.5 mC cm{sup -2}. For the potential E = 0.5 V, in the absence of O-layers, the S 2p core level spectrum indicates the presence of sulphate/bisulphate adsorbates. For E{sub as} > 1.3 V, the O 1s core level spectrum involves the contribution from water, OH- and O-species. These spectra are deconvoluted utilising either three or four Gaussian contributions with values of peaked binding energy and full width at half-maximum height (FWMH) in good agreement with expectations. The envelope of these XPS O 1s signals after correction for the contribution of sulphate/bisulphate adsorbates and adventitious carbon approaches the XPS signal that has been reported for the core level spectrum in the O 1s region of oxidised gold surfaces produced by laser pulses at different molecular oxygen pressures. The O/OH concentration ratio in the O-layer increases with E{sub as} ageing time t{sub ag} and cathodic charge density q{sub c}. The hydrous nature of the O-layer, evaluated through the analysis of the core level spectra in the O 1s region, decreases as E{sub as} and t{sub ag} are increased. Results are interesting to unravel the composition and structure of electrochemically grown O-layers at the surface of the gold substrate, and the influence of the history of these O-layers on the respective XPS features.

  20. Calorimetric studies of macromolecular aqueous solutions

    NARCIS (Netherlands)

    Blandamer, M.J; Cullis, P.M.; Engberts, J.B.F.N.

    1996-01-01

    Both titration and differential scanning microcalorimetric techniques are shown to yield important information concerning the properties of macromolecules in aqueous solution. Application of titration calorimetry is examined in me context of deaggregation of canonic micelles (e.g. hexadecyltrimethyl

  1. Phase and Texture of Solution-Processed Copper Phthalocyanine Thin Films Investigated by Two-Dimensional Grazing Incidence X-Ray Diffraction

    Directory of Open Access Journals (Sweden)

    Lulu Deng

    2011-07-01

    Full Text Available The phase and texture of a newly developed solution-processed copper phthalocyanine (CuPc thin film have been investigated by two-dimensional grazing incidence X-ray diffraction. The results show that it has β phase crystalline structure, with crystallinity greater than 80%. The average size of the crystallites is found to be about 24 nm. There are two different arrangements of crystallites, with one dominating the diffraction pattern. Both of them have preferred orientation along the thin film normal. Based on the similarities to the vacuum deposited CuPc thin films, the new solution processing method is verified to offer a good alternative to vacuum process, for the fabrication of low cost small molecule based organic photovoltaics.

  2. Structural characterization of a flexible two-domain protein in solution using small angle X-ray scattering and NMR data.

    Science.gov (United States)

    Lemak, Alexander; Wu, Bin; Yee, Adelinda; Houliston, Scott; Lee, Hsiau-Wei; Gutmanas, Aleksandras; Fang, Xianyang; Garcia, Maite; Semesi, Anthony; Wang, Yun-Xing; Prestegard, James H; Arrowsmith, Cheryl H

    2014-12-02

    Multidomain proteins in which individual domains are connected by linkers often possess inherent interdomain flexibility that significantly complicates their structural characterization in solution using either nuclear magnetic resonance (NMR) spectroscopy or small-angle X-ray scattering (SAXS) alone. Here, we report a protocol for joint refinement of flexible multidomain protein structures against NMR distance and angular restraints, residual dipolar couplings, and SAXS data. The protocol is based on the ensemble optimization method principle (Bernadó et al., 2007) and is compared with different refinement strategies for the structural characterization of the flexible two-domain protein sf3636 from Shigella flexneri 2a. The results of our refinement suggest the existence of a dominant population of configurational states in solution possessing an overall elongated shape and restricted relative twisting of the two domains.

  3. X-Ray Diffraction.

    Science.gov (United States)

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

    1980-01-01

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

  4. Pelvis x-ray

    Science.gov (United States)

    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 ...

  5. X-ray - skeleton

    Science.gov (United States)

    ... x-ray particles pass through the body. A computer or special film records the images. Structures that ... M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health ...

  6. Bone x-ray

    Science.gov (United States)

    ... or broken bone Bone tumors Degenerative bone conditions Osteomyelitis (inflammation of the bone caused by an infection) ... Multiple myeloma Osgood-Schlatter disease Osteogenesis imperfecta Osteomalacia Osteomyelitis Paget disease of the bone Rickets X-ray ...

  7. Hand x-ray

    Science.gov (United States)

    ... include fractures, bone tumors , degenerative bone conditions, and osteomyelitis (inflammation of the bone caused by an infection). ... chap 46. Read More Bone tumor Broken bone Osteomyelitis X-ray Review Date 9/8/2014 Updated ...

  8. Chest X-Ray

    Medline Plus

    Full Text Available ... breath, persistent cough, fever, chest pain or injury. It may also be useful to help diagnose and ... have some concerns about chest x-rays. However, it’s important to consider the likelihood of benefit to ...

  9. Time-resolved solution X-ray scattering of tobacco mosaic virus coat protein: kinetics and structure of intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Potschka, M.; Kock, M.H.J.; Adams, M.L.; Schuster, T.M.

    1988-11-01

    The kinetics of assembly and disassembly of tobacco mosaic virus coat protein (TMVP) following temperature jumps have been studied by small-angle X-ray scattering and turbidimetry. The structures of the principal aggregates of TMVP oligomers (A protein), intermediate size (helix I) and large size helical rods (helix II), have been characterized by their average radii of gyration of thickness, cross section, and shape obtained from the corresponding regimes of the small-angle scattering pattern. This structural information was obtained within seconds after the temperature-induced initiation of either polymerization or depolymerization and allowed the authors to detect transient intermediates. This methodology made it possible to observe and characterize the structure of a principal intermediate. Taken together with other kinetic information, these data suggest that polymerization of TMVP under virus self-assembly conditions may proceed via a single-layered helical nucleus that contains about 20 subunits. Previous studies have shown that overshoot polymerization of TMVP can occur and result in metastable long helical viruslike rods which subsequently depolymerize and then form short helical rods, depending on the conditions of the final equilibrium state. The longer rods (helix II) are overshoot polymers which form within seconds and contain 17 1/3 subunits per turn (helix IIB), in contrast to the subunit packing arrangement of 16 1/3 subunits per turn found in the shorter helical rods (helix IA). The latter packing arrangement is the one found in TMV. An overall polymerization scheme is proposed for the formation of these two helical forms of TMVP.

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... that might interfere with the x-ray images. Women should always inform their physician and x-ray ... Safety page for more information about radiation dose. Women should always inform their physician or x-ray ...

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... drawer under the table holds the x-ray film or image recording plate . Sometimes the x-ray ... extended over the patient while an x-ray film holder or image recording plate is placed beneath ...

  12. Femtosecond time-resolved X-ray absorption spectroscopy of liquid using a hard X-ray free electron laser in a dual-beam dispersive detection method.

    Science.gov (United States)

    Obara, Yuki; Katayama, Tetsuo; Ogi, Yoshihiro; Suzuki, Takayuki; Kurahashi, Naoya; Karashima, Shutaro; Chiba, Yuhei; Isokawa, Yusuke; Togashi, Tadashi; Inubushi, Yuichi; Yabashi, Makina; Suzuki, Toshinori; Misawa, Kazuhiko

    2014-01-13

    We present femtosecond time-resolved X-ray absorption spectroscopy of aqueous solution using a hard x-ray free electron laser (SACLA) and a synchronized Ti:sapphire laser. The instrumental response time is 200 fs, and the repetition rate of measurement is 10 Hz. A cylindrical liquid beam 100 μm in diameter of aqueous ammonium iron(III) oxalate solution is photoexcited at 400 nm, and the transient X-ray absorption spectra are measured in the K-edge region of iron, 7.10 - 7.26 keV, using a dual X-ray beam dispersive detection method. Each of the dual beams has the pulse energy of 1.4 μJ, and pump-induced absorbance change on the order of 10(-3) is successfully detected. The photoexcited iron complex exhibits a red shifted iron K-edge with the appearance time constant of 260 fs. The X-ray absorption difference spectra, with and without the pump pulses, are independent of time delay after 1.5 ps up to 100 ps, indicating that the photoexcited species is long-lived.

  13. Crystallization, preliminary X-ray diffraction and structure solution of MosA, a dihydrodipicolinate synthase from Sinorhizobium meliloti L5-30

    Energy Technology Data Exchange (ETDEWEB)

    Leduc, Yvonne A. [Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5 (Canada); Phenix, Christopher P. [Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9 (Canada); Puttick, Jennifer; Nienaber, Kurt [Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5 (Canada); Palmer, David R. J. [Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5 (Canada); Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9 (Canada); Delbaere, Louis T. J., E-mail: louis.delbaere@usask.ca [Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5 (Canada)

    2006-01-01

    MosA from S. meliloti L5-30 has been crystallized in solution with pyruvate and the 2.3 Å resolution structure has been solved by molecular replacement using E. coli dihydrodipicolinate synthase as the model. The structure of MosA, a dihydrodipicolinate synthase and reported methyltransferase from Sinorhizobium meliloti, has been solved using molecular replacement with Escherichia coli dihydrodipicolinate synthase as the model. A crystal grown in the presence of pyruvate diffracted X-rays to 2.3 Å resolution using synchrotron radiation and belonged to the orthorhombic space group C222{sub 1}, with unit-cell parameters a = 69.14, b = 138.87, c = 124.13 Å.

  14. X-ray diffraction study of the molecular propolis films deposited from an alcohol solution onto the cleavage surfaces of layered V2VI3 compounds

    Science.gov (United States)

    Drapak, S. I.; Gavrylyuk, S. V.; Kaminskii, V. M.; Kovalyuk, Z. D.

    2008-09-01

    The structures of the molecular propolis films deposited from an alcohol solution on the (0001) cleavage surface of layered bismuth selenide and telluride are studied by X-ray diffraction. Despite the chemical interaction between the semiconductor substrates and the organic-substance components, the molecular structural ordering of the propolis films is shown to be identical to that in the films of this substance on the surface of amorphous glass substrates. The chemical and deformation interaction between the organic substance and the layered V2VI3 compounds is found to result in the formation of an organic-inorganic sandwich nanostructure at a distance of ˜0.3 μm from the layered crystal-propolis film interface.

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

    Science.gov (United States)

    Miaja-Avila, L; O'Neil, G C; Uhlig, J; Cromer, C L; Dowell, M L; Jimenez, R; Hoover, A S; Silverman, K L; Ullom, J N

    2015-03-01

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ∼10(6) photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >10(7) laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.

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

    Directory of Open Access Journals (Sweden)

    L. Miaja-Avila

    2015-03-01

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

  17. Beyond Chandra (towards the X-ray Surveyor mission): possible solutions for the implementation of very high angular resolution X-ray telescopes in the new millennium based on fused silica segments

    Science.gov (United States)

    Pareschi, G.; Basso, S.; Civitani, M. M.; Ghigo, M.; Parodi, G.; Pelliciari, C.; Salmaso, B.; Spiga, D.; Vecchi, G.

    2016-07-01

    An important challenge for the X-ray astronomy of the new millennium is represented by the implementation of an Xray telescope able to maintain the exquisite angular resolution of Chandra (with a sub-arcsec HEW, on-axis) but, at the same time, being characterized by a much larger throughput and grasp. A mission with similar characteristics is represented by the X-ray Surveyor Mission. The project has been recently proposed in USA and is being currently studied by NASA. It will host an X-ray telescope with an effective area of more than 2 square meters at 1 keV (i.e. 30 times greater than Chandra) and a 15-arcminutes field-of-view, with 1-arcsecond or better half-power diameter (versus the 4 arcmin diameter of Chandra). While the scientific reasons for implementing a similar mission are clear, being related to compelling problems like e.g. the formation and subsequent growth of black hole seeds at very high redshift or the identification of the first galaxy groups and proto-clusters, the realization of a grazing-angle optics system able to fulfil these specs remain highly challenging. Different technologies are being envisaged, like e.g. the use of adjustable segmented mirrors (with use of piezoelectric or magneto-restrictive film actuators on the back surface) or the direct polishing of a variety of thin substrates or the use of innovative correction methods like e.g. differential deposition, ionfiguring or the correction of the profile via controlled stress films. In this paper we present a possible approach based on the direct polishing (with final ion figuring correction of the profile) of thin SiO2 segmented substrates (typically 2 mm thick), discussing different aspects of the technology under implementation and presenting some preliminary results.

  18. X-ray Pulsars

    CERN Document Server

    Walter, Roland

    2016-01-01

    X-ray pulsars shine thanks to the conversion of the gravitational energy of accreted material to X-ray radiation. The accretion rate is modulated by geometrical and hydrodynamical effects in the stellar wind of the pulsar companions and/or by instabilities in accretion discs. Wind driven flows are highly unstable close to neutron stars and responsible for X-ray variability by factors $10^3$ on time scale of hours. Disk driven flows feature slower state transitions and quasi periodic oscillations related to orbital motion and precession or resonance. On shorter time scales, and closer to the surface of the neutron star, X-ray variability is dominated by the interactions of the accreting flow with the spinning magnetosphere. When the pulsar magnetic field is large, the flow is confined in a relatively narrow accretion column, whose geometrical properties drive the observed X-ray emission. In low magnetized systems, an increasing accretion rate allows the ignition of powerful explosive thermonuclear burning at t...

  19. Sonochemical synthesis of silver nanorods by reduction of silver nitrate in aqueous solution.

    Science.gov (United States)

    Zhu, Yu-ping; Wang, Xi-kui; Guo, Wei-lin; Wang, Jin-gang; Wang, Chen

    2010-04-01

    The sonochemical synthesis of silver nanorods has been achieved by ultrasonic irradiation of the aqueous solution of silver nitrate, methenamine (HMTA) and poly (vinyl pyrrolidone) (PVP) for 60 min. The silver nanorods obtained have lengths of 4-7 microm and mean diameters of about 100 nm. The structures of the samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), selected area electron diffraction (SAED) and X-ray powder diffraction (XRD), and the chemical composition of the sample was examined by energy-dispersive X-ray spectrum (EDS). The effects of the irradiation time, the concentration of PVP and the reaction temperature on the morphology of silver nanorods were discussed, and the mechanism of the silver nanorods formation was tentatively inferred.

  20. Characterization of potassium bromide crystals grown in the aqueous solution of picric acid

    Science.gov (United States)

    Maheswari, J. Uma; Krishnan, C.; Kalyanaraman, S.; Selvarajan, P.

    2016-12-01

    Potassium bromide crystals were grown in the aqueous solution of picric acid by slow evaporation technique at room temperature. X-ray Diffraction (XRD) analysis ensures that the grown sample is in Fm3m space group and FCC structure. Energy Dispersive X-ray Spectroscopy (EDX) reveals the presence of elements in the title compound. UV-Vis-NIR spectrum reveals that the grown sample is a promising nonlinear optical (NLO) material. FTIR analysis confirms the functional groups present in the sample. The thermogravimetric (TG) and differential thermogravimetric (DTA) analyses ensure that the sample material is thermally stable up to 160 °C. The second harmonic efficiency of the sample is 1.3 times greater than that of standard KDP. The mechanical strength of the grown sample is estimated by Vickers microhardness tester. The electrical properties were investigated by impedance analysis and the results of various studies of the grown crystals are discussed.

  1. Ion spatial distributions at the liquid-vapor interface of aqueous potassium fluoride solutions.

    Science.gov (United States)

    Brown, Matthew A; D'Auria, Raffaella; Kuo, I-F William; Krisch, Maria J; Starr, David E; Bluhm, Hendrik; Tobias, Douglas J; Hemminger, John C

    2008-08-28

    X-Ray photoemission spectroscopy operating under ambient pressure conditions is used to probe ion distributions throughout the interfacial region of a free-flowing aqueous liquid micro-jet of 6 M potassium fluoride. Varying the energy of the ejected photoelectrons by carrying out experiments as a function of X-ray wavelength measures the composition of the aqueous-vapor interfacial region at various depths. The F(-) to K(+) atomic ratio is equal to unity throughout the interfacial region to a depth of 2 nm. The experimental ion profiles are compared with the results of a classical molecular dynamics simulation of a 6 M aqueous KF solution employing polarizable potentials. The experimental results are in qualitative agreement with the simulations when integrated over an exponentially decaying probe depth characteristic of an APPES experiment. First principles molecular dynamics simulations have been used to calculate the potential of mean force for moving a fluoride anion across the air-water interface. The results show that the fluoride anion is repelled from the interface, consistent with the depletion of F(-) at the interface revealed by the APPES experiment and polarizable force field-based molecular dynamics simulation. Together, the APPES and MD simulation data provide a detailed description of the aqueous-vapor interface of alkali fluoride systems. This work offers the first direct observation of the ion distribution at an aqueous potassium fluoride solution interface. The current experimental results are compared to those previously obtained for saturated solutions of KBr and KI to underscore the strong difference in surface propensity between soft/large and hard/small halide ions in aqueous solution.

  2. X-Ray Protection

    Science.gov (United States)

    1955-01-01

    15,000. • When developed In Kodak liquid X-ray developer for 5 min at a temperature of 200 C. b Film sensitivities vary with photon energy by the...for example temporomandibular -joint exposures where a skin dose of 25 r or more may be obtained during a single exposure with 65 kvp, 1.5 mm aluminum...communication. W. J. Updegrave, Temporomandibular articulation-X-ray examina- tion, Dental Radiography and Photography 26, No. 3, 41 (1953). H. 0. Wyckoff, R. J

  3. Solution structure of the complex between CR2 SCR 1-2 and C3d of human complement: an X-ray scattering and sedimentation modelling study.

    Science.gov (United States)

    Gilbert, Hannah E; Eaton, Julian T; Hannan, Jonathan P; Holers, V Michael; Perkins, Stephen J

    2005-02-25

    Complement receptor type 2 (CR2, CD21) forms a tight complex with C3d, a fragment of C3, the major complement component. Previous crystal structures of the C3d-CR2 SCR 1-2 complex and free CR2 SCR 1-2 showed that the two SCR domains of CR2 form contact with each other in a closed V-shaped structure. SCR 1 and SCR 2 are connected by an unusually long eight-residue linker peptide. Medium-resolution solution structures for CR2 SCR 1-2, C3d, and their complex were determined by X-ray scattering and analytical ultracentrifugation. CR2 SCR 1-2 is monomeric. For CR2 SCR 1-2, its radius of gyration R(G) of 2.12(+/-0.05) nm, its maximum length of 10nm and its sedimentation coefficient s20,w(o) of 1.40(+/-0.03) S do not agree with those calculated from the crystal structures, and instead suggest an open structure. Computer modelling of the CR2 SCR1-2 solution structure was based on the structural randomisation of the eight-residue linker peptide joining SCR 1 and SCR 2 to give 9950 trial models. Comparisons with the X-ray scattering curve indicated that the most favoured arrangements for the two SCR domains corresponded to an open V-shaped structure with no contacts between the SCR domains. For C3d, X-ray scattering and sedimentation velocity experiments showed that it exists as a monomer-dimer equilibrium with a dissociation constant of 40 microM. The X-ray scattering curve for monomeric C3d gave an R(G) value of 1.95 nm, and this together with its s20,w(o) value of 3.17 S gave good agreement with the monomeric C3d crystal structure. Modelling of the C3d dimer gave good agreements with its scattering and ultracentrifugation parameters. For the complex, scattering and ultracentrifugation experiments showed that there was no dimerisation, indicating that the C3d dimerisation site was located close to the CR2 SCR 1-2 binding site. The R(G) value of 2.44(+/-0.1) nm, its length of 9 nm and its s20,w(o) value of 3.45(+/-0.01) S showed that its structure was not much more

  4. Copper(II) ion catalytic oxidation of o-phenylenediamine and characterization, X-ray crystal structure and solution studies of the final product [DAPH][H3O][Cu(dipic)2]·3H2O

    Science.gov (United States)

    Ghasemi, Khaled; Rezvani, Ali Reza; Shokrollahi, Ardeshir; Abdul Razak, Ibrahim; Refahi, Masoud; Moghimi, Abolghasem; Rosli, Mohd Mustaqim

    2015-09-01

    The complex [DAPH][H3O][Cu(dipic)2]·3H2O, (1) (dipicH2 = 2,6-pyridinedicarboxylic acid and DAP = 2,3-diaminophenazine) was prepared from the reaction of Cu(NO3)2·2H2O with mixture of o-phenylenediamine (OPD) and 2,6-pyridinedicarboxylic acid in water. The complex was characterized by FTIR, elemental analysis, UV-Vis and the single-crystal X-ray diffraction. The crystal system is monoclinic with the space group P21/c. This complex is stabilized in the solid state by an extensive network of hydrogen bonds between crystallized water, anionic and cationic fragments, which form a three-dimensional network. Furthermore, hydrogen bonds, π⋯π and Csbnd O⋯π stacking interactions seem to be effective in stabilizing the crystal structures. The protonation constants of dipic (L) and DAP (Q), the equilibrium constants for the dipic-DAP proton transfer system and the stoichiometry and stability constants of binary complexes including each of ligands (dipic, DAP) in presence Cu2+ ion, ternary complexes including, both of ligands (dipic-DAP) in presence of metal ion were calculated in aqueous solutions by potentiometric pH titration method using the Hyperquad2008 program. The stoichiometry of the most complexes species in solution was found to be very similar to the solid-state of cited metal ion complex.

  5. Columnar molecular aggregation in the aqueous solutions of disodium cromoglycate

    Science.gov (United States)

    Agra-Kooijman, Dena M.; Singh, Gautam; Lorenz, Alexander; Collings, Peter J.; Kitzerow, Heinz-S.; Kumar, Satyendra

    2014-06-01

    Stack, chimneylike, and threadlike assemblies have previously been proposed for the structure of disodium cromoglycate (DSCG) aggregates in aqueous solutions. The results of the synchrotron x-ray scattering investigations reported here reveal the formation of simple columnar assemblies with π-π stacking at a separation of 3.4 Å between the DSCG molecules. Lateral separation between the assemblies is concentration and temperature dependent, varying from ˜35 to 42 Å in the orientationally ordered nematic (N) phase and from 27 to 32 Å in the columnar or middle (M) phase having long range lateral positional order. The assemblies' length depends on concentration and consists of ˜23 molecules in the N phase, becoming three to ten times larger in the M phase. The scission energy is concentration dependent in the N phase with values ˜7.19 ± 0.14 kBT (15 wt %), 2.73 ± 0.4 kBT (20 wt %), and 3.05 ± 0.2 kBT (25 wt %). Solutions of all concentrations undergo a spinodal decomposition at temperatures above ˜40 °C, resulting in DSCG-rich regions with the M phase and water-rich regions in the N and isotropic phases.

  6. Femtosecond X-Ray Scattering Study of Ultrafast Photoinduced Structural Dynamics in Solvated [Co(terpy)2]2+

    DEFF Research Database (Denmark)

    Biasin, Elisa; Brandt van Driel, Tim; Kjær, Kasper Skov;

    2016-01-01

    We study the structural dynamics of photoexcited [Co(terpy)2]2+ in an aqueous solution with ultrafast x-ray diffuse scattering experiments conducted at the Linac Coherent Light Source. Through direct comparisons with density functional theory calculations, our analysis shows that the photoexcitat......We study the structural dynamics of photoexcited [Co(terpy)2]2+ in an aqueous solution with ultrafast x-ray diffuse scattering experiments conducted at the Linac Coherent Light Source. Through direct comparisons with density functional theory calculations, our analysis shows...

  7. X-ray excited photoluminescence near the giant resonance in solid-solution Gd(1-x)Tb(x)OCl nanocrystals and their retention upon solvothermal topotactic transformation to Gd(1-x)Tb(x)F3.

    Science.gov (United States)

    Waetzig, Gregory R; Horrocks, Gregory A; Jude, Joshua W; Zuin, Lucia; Banerjee, Sarbajit

    2016-01-14

    Design rules for X-ray phosphors are much less established as compared to their optically stimulated counterparts owing to the absence of a detailed understanding of sensitization mechanisms, activation pathways and recombination channels upon high-energy excitation. Here, we demonstrate a pronounced modulation of the X-ray excited photoluminescence of Tb(3+) centers upon excitation in proximity to the giant resonance of the host Gd(3+) ions in solid-solution Gd1-xTbxOCl nanocrystals prepared by a non-hydrolytic cross-coupling method. The strong suppression of X-ray excited optical luminescence at the giant resonance suggests a change in mechanism from multiple exciton generation to single thermal exciton formation and Auger decay processes. The solid-solution Gd1-xTbxOCl nanocrystals are further topotactically transformed with retention of a nine-coordinated cation environment to solid-solution Gd1-xTbxF3 nanocrystals upon solvothermal treatment with XeF2. The metastable hexagonal phase of GdF3 can be stabilized at room temperature through this topotactic approach and is transformed subsequently to the orthorhombic phase. The fluoride nanocrystals indicate an analogous but blue-shifted modulation of the X-ray excited optical luminescence of the Tb(3+) centers upon X-ray excitation near the giant resonance of the host Gd(3+) ions.

  8. Investigation of optical spacer layers from solution based precursors for polymer solar cells using X-ray reflectometry

    DEFF Research Database (Denmark)

    Andersen, Philip Hvidthøft Delff; Skårhøj, Jakob; Andreasen, Jens Wenzel

    2009-01-01

    Optical spacer layers based on titaniumalkoxide precursor solutions were prepared by spin-coating on top of bulk heterojunction layers based on poly-3-hexylthiophene (P3HT) and phenyl-C61-butyric acid methylester (PCBM). Models and experiment have shown that the performance of polymer solar cells...

  9. Hydrophobic Solvation: Aqueous Methane Solutions

    Science.gov (United States)

    Konrod, Oliver; Lankau, Timm

    2007-01-01

    A basic introduction to concept of a solvation shell around an apolar solute as well as its detection is presented. The hydrophobic solvation of toluene is found to be a good teaching example which connects macroscopic, phenomenological thermodynamic results with an atomistic point of view.

  10. Tetraethyl Orthosilicate Coated Hydroxyapatite Powders for Lead Ions Removal from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Rodica V. Ghita

    2014-01-01

    Full Text Available The goal of this study was to synthetize and characterize a porous material based on tetraethyl orthosilicate (TEOS coated hydroxyapatite (HApTh after removal experiments of Pb2+ ions from aqueous solutions. In order to study the morphology and composition, the samples obtained after removal experiments of Pb2+ ions from aqueous solution with the initial Pb2+ ion concentrations of the aqueous solutions were 0.1 g·L−1 (HApTh-50 and 0.9 g·L−1 (HApTh-450 have been investigated by scanning electron microscopy (SEM equipped with an energy dispersive X-ray spectrometer (EDS, Fourier transform infrared spectroscopy (FTIR, and transmission electron microscopy (TEM. Removal experiments of Pb2+ ions were carried out in aqueous solutions with controlled concentration of Pb2+. After the removal experiment of Pb2+ ions from solutions, porous hydroxyapatite nanoparticles were transformed into HApTh-50 and HApTh-450 due to the adsorption of Pb2+ ions followed by a cation exchange reaction. The obtained results show that the porous HApTh nanopowders could be used for Pb2+ ions removal from aqueous solutions.

  11. Structural analysis of flexible proteins in solution by SmallAngle X-ray Scattering combined with crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Tsutakawa, Susan E.; Hura, Greg L.; Frankel, Ken A.; Cooper,Priscilla K.; Tainer, John A.

    2006-05-25

    In the last few years, SAXS of biological materials has been rapidly evolving and promises to move structural analysis to a new level. Recent innovations in SAXS data analysis allow ab initio shape predictions of proteins in solution. Furthermore, experimental scattering data can be compared to calculated scattering curves from the growing data base of solved structures and also identify aggregation and unfolded proteins. Combining SAXS results with atomic resolution structures enables detailed characterizations in solution of mass, radius, conformations, assembly, and shape changes associated with protein folding and functions. SAXS can efficiently reveal the spatial organization of protein domains, including domains missing from or disordered in known crystal structures, and establish cofactor or substrate-induced conformational changes. For flexible domains or unstructured regions that are not amenable for study by many other structural techniques, SAXS provides a unique technology. Here, we present SAXS shape predictions for PCNA that accurately predict a trimeric ring assembly and for a full-length DNA repair glycosylase with a large unstructured region. These new results in combination with illustrative published data show how SAXS combined with high resolution crystal structures efficiently establishes architectures, assemblies, conformations, and unstructured regions for proteins and protein complexes in solution.

  12. The 4D evolution of porosity during ongoing pressure-solution processes in NaCl using x-ray microtomography

    Science.gov (United States)

    Macente, Alice; Fusseis, Florian; Butler, Ian; Tudisco, Erika; Hall, Stephen; Andò, Edward

    2016-04-01

    Pressure-solution creep is a common deformation mechanism in the upper crust. It represents a mass transfer via dissolution-reprecipitation that critically affects the hydraulic properties of rocks. Successful management of safe radioactive storage sites in rock-salt deposits critically depends on an accurate knowledge of the hydro-mechanical behaviour of salt deposits. Despite numerous lab experiments that have been conducted, many aspects of pressure-solution are still poorly understood. There is little knowledge about the spatio-temporal evolution of porosity and permeability during pressure-solution creep. While rates of pressure-solution creep in silicates and carbonates are slow, which makes laboratory investigations of these materials impractical, compaction experiments have demonstrated that NaCl samples deform sufficiently fast to study pressure-solution creep in a lab environment at room temperature and modest loads. We present results from novel experiments that quantify the 4-dimensional (three spatial dimensions plus time) evolution of pressure-solution processes using in-situ x-ray microtomography. Our experiments are performed in custom made x-ray transparent presses. 5 mm diameter NaCl powder samples with a grain size of 250-300 μm are loaded dry into the press and pre-compacted to produce a starting aggregated material. The sample is then flooded with saturated NaCl solution and loaded uniaxially by means of a pneumatic actuator to a constant uniaxial stress. Different sample mixtures were tested, as well as different uniaxial loads. The resulting deformation of the samples is documented in 3-dimensional microtomographic datasets, acquired at regular time intervals. Image analysis allowed characterization of the microstructural evolution of the NaCl grains and the spatio-temporal distribution of porosity during ongoing mechanical and chemical compaction. The microtomography data have also been analysed with 3D Digital Image Correlation (3D-DIC or

  13. Electrochemical deposition of coatings of highly entropic alloys from non-aqueous solutions

    Directory of Open Access Journals (Sweden)

    Jeníček V.

    2016-03-01

    Full Text Available The paper deals with electrochemical deposition of coatings of highly entropic alloys. These relatively new materials have been recently intensively studied. The paper describes the first results of electrochemical coating with highly entropic alloys by deposition from non-aqueous solutions. An electrochemical device was designed and coatings were deposited. The coatings were characterised with electronic microscopy scanning, atomic absorption spectrometry and X-ray diffraction methods and the combination of methods of thermic analysis of differential scanning calorimetry and thermogravimetry.

  14. Aqueous Solution Chemistry on Mars

    Science.gov (United States)

    Quinn, R.; Hecht, M.; Kounaves, S.; Young, S.; West, S.; Fisher, A.; Grunthaner, P.

    2007-12-01

    Currently en route to Mars, the Phoenix mission carries four wet chemistry cells designed to perform basic solution chemistry on martian soil. The measurement objectives are typical of those that would be performed on an unknown sample on Earth, including detection of common anions and cations, total conductivity, pH, redox potential, cyclic voltammetry (CV), etc. Both the challenge and the novelty arise from the necessity to perform these measurements with severely constrained resources in a harsh and (literally) alien environment. Sensors for all measurements are integrated into a common "beaker," with the ability to perform a two-point calibration of some sensors using a pair of low-concentration solutions. Sulfate measurement is performed with a crude titration. While most measurements use ion selective electrodes, halide interferences are resolved by independent chronopotentiometry (CP) measurements. No preconditioning of the soil-water mixture is possible, nor is any physical characterization of the introduced soil sample beyond coarse visual inspection. Among the idiosyncrasies of the measurement is the low external pressure, which requires that the analysis be performed close to the boiling point of water under an atmosphere consisting almost entirely of water vapor. Despite these liabilities, however, extensive laboratory characterization has validated the basic approach, and protocols for both CV and CP have been developed and tested. Enhancing the value of the measurement is the suite of coordinated observations, such as microscopy and evolved gas analysis, to be performed by other Phoenix instruments.

  15. Biosorption of arsenic from aqueous solution using dye waste.

    Science.gov (United States)

    Nigam, Shubha; Vankar, Padma S; Gopal, Krishna

    2013-02-01

    The purpose of this study is to examine on removal of arsenic from water by biosorption through potential application of herbal dye wastes. Four different flower dye residues (after extraction of natural dye) viz. Hibiscus rosasinensis, Rosa rosa, Tagetes erecta, and Canna indica were utilized successfully for the removal of arsenic from aqueous solution. Batch studies were carried out for various parameters viz. pH, sorbent dose, contact time, initial metal ion concentration, and temperature. Data were utilized for isothermal, kinetic, and thermodynamic studies. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDAX), and Fourier transform infrared (FTIR) analyses of biomass were performed. The results showed that 1 g/100 ml for 5.0-5.5 h contact time at pH 6.0-7.5 with agitation rate 150 rpm provided 98, 96, 92, and 85 % maximum absorption of arsenic by R. rosa, H. rosasinensis, T. erecta, and C. indica, respectively, at initial concentration of 500 ppb. Data followed Langmuir isotherm showing sorption to be monolayer on heterogeneous surface of biosorbent. Negative values of ΔG° indicated spontaneous nature, whereas ΔH° indicates exothermic nature of system followed by pseudo-first-order adsorption kinetics. FTIR results showed apparent changes in functional group regions after metal chelation. SEM and EDAX analyses showed the changes in surface morphology of all test biosorbents. Herbal dye wastes, used as biosorbent, exhibited significant (85-98 %) removal of arsenic from aqueous solution. Hence, these biosorbents are cost-effective, easily available, eco-friendly, and comparatively more effective than other biosorbents already in use. These may be used to remove arsenic and other toxic metals from water.

  16. X-ray diffraction analysis and molecular-replacement solution of the cyan fluorescent protein dsFP483

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Meitian; Patel, Hetal N.; Wachter, Rebekka M., E-mail: rwachter@asu.edu [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona (United States)

    2005-10-01

    The coral-derived cyan fluorescent protein dsFP483 has been crystallized and diffraction data were collected to 2.1 Å. A molecular-replacement solution is presented for 83% of the protein contents of the asymmetric unit. A novel cyan fluorescent protein, dsFP483 from the coral Discosoma striata, has been crystallized. Diffraction data were collected to 2.1 Å and processed in space group C2. Molecular-replacement methods were applied using the closely related red fluorescent protein DsRed as a search model. The asymmetric unit appears to contain six protein molecules (1.5 tetramers), five of which (83%) could be located by the molecular-replacement searches.

  17. EXAFS study of the speciation of protactinium(V) in aqueous hydrofluoric acid solutions.

    Science.gov (United States)

    De Sio, Stéphanie M; Wilson, Richard E

    2014-12-01

    The speciation of protactinium(V) in hydrofluoric acid (HF) solutions was studied using X-ray absorption spectroscopy. Extended X-ray absorption fine structure measurements were performed on an aqueous solution of 0.05 M protactinium(V) with various HF concentrations ranging from 0.5 to 27 M in order to probe the protactinium coordination sphere with respect to the identity and number of coordinating ligands. The resulting fits to the spectra suggest the presence of an eight-coordinate homoleptic fluoro complex in highly concentrated fluoride solutions (27 M), with equilibrium between seven- and eight-coordinate fluoro complexes at moderate acidities, and in more dilute solutions, results indicate that one water molecule is likely to replace a fluoride in the first coordination sphere, at a distance of 2.54-2.57 Å. Comparisons of this chemistry with group V metals, niobium and tantalum, are presented, and the potential implications for these results on the hydrolytic behavior of protactinium in aqueous systems are discussed.

  18. Water & Aqueous Solutions. Final Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-08-09

    The Gordon Research Conference (GRC) on Water & Aqueous Solutions was held at Holderness School, New Hampshire, 8/4/02 thru 8/9/02. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  19. Crystallization and preliminary X-ray diffraction analysis of two extracytoplasmic solute receptors of the DctP family from Bordetella pertussis

    Energy Technology Data Exchange (ETDEWEB)

    Rucktooa, Prakash; Huvent, Isabelle [UMR8161 CNRS Institut de Biologie de Lille, Laboratoire de Cristallographie Macromoléculaire, 1 Rue du Professeur Calmette, BP 447, 59021 Lille CEDEX (France); IFR 142, Institut Pasteur de Lille, 1 Rue du Professeur Calmette, BP 245, 59021 Lille CEDEX (France); Antoine, Rudy; Lecher, Sophie; Jacob-Dubuisson, Françoise, E-mail: francoise.jacob@ibl.fr [IFR 142, Institut Pasteur de Lille, 1 Rue du Professeur Calmette, BP 245, 59021 Lille CEDEX (France); INSERM-U629, Lille (France); Institut Pasteur de Lille, 1 Rue du Professeur Calmette, BP 245, 59021 Lille CEDEX (France); Villeret, Vincent, E-mail: francoise.jacob@ibl.fr; Bompard, Coralie [UMR8161 CNRS Institut de Biologie de Lille, Laboratoire de Cristallographie Macromoléculaire, 1 Rue du Professeur Calmette, BP 447, 59021 Lille CEDEX (France); IFR 142, Institut Pasteur de Lille, 1 Rue du Professeur Calmette, BP 245, 59021 Lille CEDEX (France)

    2006-10-01

    Sample preparation, crystallization and preliminary X-ray analysis are reported for two B. pertussis extracytoplasmic solute receptors. DctP6 and DctP7 are two Bordetella pertussis proteins which belong to the extracytoplasmic solute receptors (ESR) superfamily. ESRs are involved in the transport of substrates from the periplasm to the cytosol of Gram-negative bacteria. DctP6 and DctP7 have been crystallized and diffraction data were collected using a synchrotron-radiation source. DctP6 crystallized in space group P4{sub 1}2{sub 1}2, with unit-cell parameters a = 108.39, b = 108.39, c = 63.09 Å, while selenomethionyl-derivatized DctP7 crystallized in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 64.87, b = 149.83, c = 170.65 Å. The three-dimensional structure of DctP7 will be determined by single-wavelength anomalous diffraction, while the DctP6 structure will be solved by molecular-replacement methods.

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

    Science.gov (United States)

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

    2015-03-01

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

  1. SORPTION OF Cu2+ FROM AQUEOUS SOLUTIONS BY SLOVAK BENTONITES

    Directory of Open Access Journals (Sweden)

    ANNA BRTÁŇOVÁ

    2012-03-01

    Full Text Available Bentonites are used as barriers in landfills, or in areas of old mining activities to prevent contamination of environment by leachates containing heavy metals. Batch experiments were performed under static conditions to study sorption of Cu2+ from aqueous solutions via adsorption on industrial products made from Slovak bentonites Lieskovec and Jelšový Potok. The samples were characterized by X-ray powder diffraction, infrared spectroscopy and by specific surface area and cation exchange capacities measurements. Effects of pH, concentration of metal cations and contact time were analysed. The adsorption was strongly dependent on pH of the medium, and the uptake of adsorbed metal increased from pH 2.0 to 6.5, while the solubility of Cu at higher pH values decreased. The uptake of Cu2+ was rapid and it increased with increasing metal concentration, while the relative amount of adsorbed Cu2+ decreased. The equilibrium adsorption capacity of the adsorbents used for Cu2+ was extrapolated using the linear Freundlich and Langmuir adsorption isotherms. The Langmuir isotherm was found to fit better the experimental data measured for both bentonites.

  2. Modeling platinum group metal complexes in aqueous solution.

    Science.gov (United States)

    Lienke, A; Klatt, G; Robinson, D J; Koch, K R; Naidoo, K J

    2001-05-07

    We construct force fields suited for the study of three platinum group metals (PGM) as chloranions in aqueous solution from quantum chemical computations and report experimental data. Density functional theory (DFT) using the local density approximation (LDA), as well as extended basis sets that incorporate relativistic corrections for the transition metal atoms, has been used to obtain equilibrium geometries, harmonic vibrational frequencies, and atomic charges for the complexes. We found that DFT calculations of [PtCl(6)](2-).3H(2)O, [PdCl(4)](2-).2H(2)O, and [RhCl(6)](3-).3H(2)O water clusters compared well with molecular mechanics (MM) calculations using the specific force field developed here. The force field performed equally well in condensed phase simulations. A 500 ps molecular dynamics (MD) simulation of [PtCl(6)](2-) in water was used to study the structure of the solvation shell around the anion. The resulting data were compared to an experimental radial distribution function derived from X-ray diffraction experiments. We found the calculated pair correlation functions (PCF) for hexachloroplatinate to be in good agreement with experiment and were able to use the simulation results to identify and resolve two water-anion peaks in the experimental spectrum.

  3. Morphology control of brushite prepared by aqueous solution synthesis

    Directory of Open Access Journals (Sweden)

    T. Toshima

    2014-03-01

    Full Text Available Dicalcium phosphate dihydrate (DCPD, CaHPO4·2H2O, also known as brushite, is one of the important bioceramics due to not only diseases factors such as kidney stone and plaque formation but also purpose as fluoride insolubilization material. It is used medicinally to supply calcium, and is of interest for its unique properties in biological and pathological mineralization. It is important to control the crystal morphology of brushite since its chemical reactivity depends strongly on its surface properties; thus, its morphology is a key issue for its applications as a functional material or precursor for other bioceramics. Here, we report the effects of the initial pH and the Ca and phosphate ion concentrations on the morphology of DCPD particles during aqueous solution synthesis. Crystal morphologies were analyzed by scanning electron microscopy and X-ray diffraction. The morphology phase diagram of DCPD crystallization revealed that increasing the initial pH and/or ion concentration transformed DCPD morphology from petal-like into plate-like structures.

  4. X-Ray Astronomy

    Science.gov (United States)

    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. Synthesis of magnetic biocomposite for efficient adsorption of azo dye from aqueous solution.

    Science.gov (United States)

    Sivashankar, R; Sathya, A B; Krishnakumar, Uma; Sivasubramanian, V

    2015-11-01

    A novel magnetic biocomposite was synthesized using metal chlorides and aquatic macrophytes by co-precipitation method. The resulting product, magnetic biocomposite was characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX) and Scanning electron microscope (SEM). The adsorption performance of the magnetic biocomposite was tested with removal of Metanil Yellow dye from aqueous solution. The effect of influencing parameters such as initial dye concentration, solution pH and agitation were investigated. The equilibrium isotherm was well described by the Langmuir model with the with maximum adsorption capacity of 90.91mg/g. Adsorption kinetics experiments were carried out and the data were well fitted by a pseudo-second-order equation. The results revealed that the magnetic biocomposite could efficiently adsorb the azo dyes from aqueous solution, and the spent adsorbents could be recovered completely by magnetic separation process. Therefore, the prepared magnetic biocomposite could thus be used as promising adsorbent for the removal of azo dyes from polluted water.

  6. Enhanced removal of Hg(II) from acidic aqueous solution using thiol-functionalized biomass.

    Science.gov (United States)

    Chai, Liyuan; Wang, Qingwei; Li, Qingzhu; Yang, Zhihui; Wang, Yunyan

    2010-01-01

    Spent grain, the low-cost and abundant biomass produced in the brewing industry, was functionalized with thiol groups to be used as an adsorbent for Hg(II) removal from acidic aqueous solution. The adsorbents were characterized by the energy-dispersive X-ray analysis (EDAX) and Fourier transform infrared (FTIR) spectroscopy. Optimum pH for Hg(II) adsorption onto the thiol-functionalized spent grain (TFSG) was 2.0. The equilibrium and kinetics of the adsorption of Hg(II) onto TFSG from acidic aqueous solution were investigated. From the Langmuir isotherm model the maximum adsorption capacity of TFSG for Hg(II) was found to be 221.73 mg g(-1), which was higher than that of most various adsorbents reported in literature. Moreover, the adsorption of Hg(II) onto TFSG followed pseudo-second-order kinetic model.

  7. Removal of Indigo Carmine Dye from Aqueous Solution Using Magnesium Hydroxide as an Adsorbent

    Directory of Open Access Journals (Sweden)

    Thimmasandra Narayan Ramesh

    2015-01-01

    Full Text Available Magnesium hydroxide is used as an adsorbent for the removal of indigo carmine dye from aqueous solution. We have investigated the effectiveness of removal of indigo carmine dye from aqueous solutions at pH 6-7 and 12-13 using magnesium hydroxide thereby varying the dose of the adsorbent, concentration of the dye, duration, and temperature. Structural transformations of adsorbent during the adsorption process at different pH values are monitored using powder X-ray diffraction and infrared spectroscopy. Different types of adsorption isotherm models were evaluated and it was found that Langmuir isotherm fits well at both pH values (6-7 and 12-13. Adsorption of indigo carmine onto magnesium hydroxide at pH 6-7/pH 12-13 follows pseudo-second order rate kinetics.

  8. Comparative X-ray diffraction study of the crystalline microstructure of tetragonal and monoclinic vanadium-zirconium dioxide solid solutions produced from gel precursors

    Energy Technology Data Exchange (ETDEWEB)

    Kojdecki, Marek Andrzej [Wojskowa Akademia Techniczna, Warszawa (Poland). Inst. Matematyki i Kryptologii; Ruiz de Sola, Esther; Alarcon, Javier [Valencia Univ., Burjasot (Spain). Dept. de Quimica Inorganica; Serrano, Francisco Javier; Amigo, Jose Maria [Valencia Univ., Burjasot (Spain). Dept. de Geologia

    2009-04-15

    The microstructural characteristics of solid solutions, prepared by heating dried gel precursors with nominal compositions V{sub x}Zr{sub 1-x}O{sub 2} (0{<=}x{<=}0.1) at 723 and 1573 K, were determined from X-ray diffraction patterns. The crystalline microstructure of the resulting specimens, characterized by a prevalent crystallite shape, a volume-weighted crystallite size distribution and a second-order lattice strain distribution, was found to depend on the vanadium content. A characteristic feature of all size distributions was their bimodality, explained as a result of transformations between tetragonal and monoclinic phases during thermal treatment. A comparative study of the microstructure of both zirconia phases has been carried out, enabling reconstruction of a probable course of crystallization of both pure and vanadium-doped zirconias: on heating a sample, nucleation and the early growth stages involve crystallites of both phases; then on annealing and cooling, the crystallites of one phase transform into the other, depending on the thermal treatment temperature. Each logarithmic normal component of the crystallite size distribution of the resulting phase can be attributed to one of these processes. The limit of solubility of vanadium in tetragonal and monoclinic zirconia is estimated from the microstructural characteristics. (orig.)

  9. Synthesis and X-ray diffraction study of Cu{sub 2}ZnSn(S{sub x}Se{sub 1-x}){sub 4} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Sheleg, A. U., E-mail: hurtavy@physics.by; Hurtavy, V. G.; Chumak, V. A. [State Scientific and Production Association “Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus,” (Belarus)

    2015-09-15

    Quaternary compounds Cu{sub 2}ZnSnS{sub 4} and Cu{sub 2}ZnSnSe{sub 4} and solid solutions on their basis have been fabricated by one-temperature synthesis from elementary components: Cu, Zn, Sn, S, and Se. Single crystals of these compounds have been grown by the method of chemical gas-transport reactions from polycrystalline samples. The compositional dependence of the unit-cell parameters of Cu{sub 2}ZnSn(S{sub x}Se{sub 1–x}){sub 4} has been investigated by X-ray diffraction. It is found that parameters a and c linearly decrease with an increase in sulfur concentration in accordance with Vegard’s law. The temperature dependences of parameters a and thermalexpansion coefficients α{sub a} of Cu{sub 2}ZnSnS{sub 4} and Cu{sub 2}ZnSnSe{sub 4} single crystals in the range of 100–300 K are determined.

  10. Estimation of kinetic parameters of the passive state of carbon steel in mildly alkaline solutions from electrochemical impedance spectroscopic and X-ray photoelectron spectroscopic data

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.; Wren, J.C. [Department of Chemistry, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 5B7 (Canada); Betova, I. [Department of Chemistry, Technical University of Sofia, 1000 Sofia (Bulgaria); Bojinov, M., E-mail: martin@uctm.edu [Department of Physical Chemistry, University of Chemical Technology and Metallurgy, 1756 Sofia (Bulgaria)

    2011-07-01

    Highlights: > The passive state of carbon steel is described using the Mixed-Conduction Model for oxide films. > Kinetic parameters are estimated by comparison of the model to EIS and XPS data. > The passive film is intermediate between magnetite and maghemite. > Relevance of film growth and dissolution reactions for corrosion is discussed. - Abstract: The unambiguous interpretation of electrochemical impedance spectra of complex systems such as passive metals and alloys in terms of an unique kinetic model is often hampered by the large number of adjustable modeling parameters. In this paper, a combination of in situ electrochemical data and ex situ surface analytical information is employed to validate the estimates of kinetic and transport parameters of the passive state of carbon steel. For the purpose, electrochemical impedance spectroscopic and X-ray photoelectron spectroscopic data for the oxidation of carbon steel in mildly alkaline solutions are quantitatively compared with the predictions of the Mixed-Conduction Model for oxide films that represent the passive oxide as an intermediate phase between magnetite and maghemite. Estimates of the kinetic rate constants at the film interfaces, as well as the diffusion coefficients and field strength in the film are obtained and their relevance for the corrosion mechanism of carbon steel is discussed.

  11. Cooperative protein structural dynamics of homodimeric hemoglobin linked to water cluster at subunit interface revealed by time-resolved X-ray solution scattering.

    Science.gov (United States)

    Kim, Jong Goo; Muniyappan, Srinivasan; Oang, Key Young; Kim, Tae Wu; Yang, Cheolhee; Kim, Kyung Hwan; Kim, Jeongho; Ihee, Hyotcherl

    2016-03-01

    Homodimeric hemoglobin (HbI) consisting of two subunits is a good model system for investigating the allosteric structural transition as it exhibits cooperativity in ligand binding. In this work, as an effort to extend our previous study on wild-type and F97Y mutant HbI, we investigate structural dynamics of a mutant HbI in solution to examine the role of well-organized interfacial water cluster, which has been known to mediate intersubunit communication in HbI. In the T72V mutant of HbI, the interfacial water cluster in the T state is perturbed due to the lack of Thr72, resulting in two less interfacial water molecules than in wild-type HbI. By performing picosecond time-resolved X-ray solution scattering experiment and kinetic analysis on the T72V mutant, we identify three structurally distinct intermediates (I1, I2, and I3) and show that the kinetics of the T72V mutant are well described by the same kinetic model used for wild-type and F97Y HbI, which involves biphasic kinetics, geminate recombination, and bimolecular CO recombination. The optimized kinetic model shows that the R-T transition and bimolecular CO recombination are faster in the T72V mutant than in the wild type. From structural analysis using species-associated difference scattering curves for the intermediates, we find that the T-like deoxy I3 intermediate in solution has a different structure from deoxy HbI in crystal. In addition, we extract detailed structural parameters of the intermediates such as E-F distance, intersubunit rotation angle, and heme-heme distance. By comparing the structures of protein intermediates in wild-type HbI and the T72V mutant, we reveal how the perturbation in the interfacial water cluster affects the kinetics and structures of reaction intermediates of HbI.

  12. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... fracture. guide orthopedic surgery, such as spine repair/fusion, joint replacement and fracture reductions. look for injury, ... and Media Arthritis X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety Images related to X-ray ( ...

  13. Abdomen X-Ray (Radiography)

    Science.gov (United States)

    ... Professions Site Index A-Z X-ray (Radiography) - Abdomen Abdominal x-ray uses a very small dose ... to produce pictures of the inside of the abdominal cavity. It is used to evaluate the stomach, liver, ...

  14. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  15. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... patient. top of page How does the procedure work? X-rays are a form of radiation like ... very controlled x-ray beams and dose control methods to minimize stray (scatter) radiation. This ensures that ...

  16. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... radiation like light or radio waves. X-rays pass through most objects, including the body. Once it ... organs, allow more of the x-rays to pass through them. As a result, bones appear white ...

  17. Panoramic Dental X-Ray

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Panoramic Dental X-ray Panoramic dental x-ray uses a ... Your e-mail address: Personal message (optional): Bees: Wax: Notice: RadiologyInfo respects your privacy. Information entered here ...

  18. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the body. X-rays are the oldest and most frequently used form of medical imaging. A bone ... bones. top of page How should I prepare? Most bone x-rays require no special preparation. You ...

  19. Soft X-ray Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Seely, John

    1999-05-20

    The contents of this report cover the following: (1) design of the soft x-ray telescope; (2) fabrication and characterization of the soft x-ray telescope; and (3) experimental implementation at the OMEGA laser facility.

  20. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... of page What are some common uses of the procedure? A bone x-ray is used to: ... and x-rays. top of page What does the equipment look like? The equipment typically used for ...

  1. Aqueous solubility study of salts of benzylamine derivatives and p-substituted benzoic acid derivatives using X-ray crystallographic analysis

    DEFF Research Database (Denmark)

    Parshad, Henrik; Frydenvang, Karla Andrea; Liljefors, Tommy;

    2004-01-01

    than those reported for the corresponding salts of benzylamine (I). Thermal analysis indicated that the increased solubility was caused by reduced crystal lattice energy, which was most likely due to the reduced number of strong hydrogen bonds of the salt of (II) and (III). X-ray crystallographic...... analysis of p-hydroxybenzoic acid salt of (I), (II) and (III) suggested that the reduced number of hydrogen bonds caused the apparent higher solubility. Further analyses of seven salts of (I) were performed. It was not possible to identify any relationship between the number of hydrogen bonds......Twenty two p-substituted benzoic acid derivates were used to prepare salts of N-methylbenzylamine (II) and N,N-dimethylbenzylamine (III), respectively. Only five salts of (II) and two salts of (III) were obtained in a crystalline state. The solubility of these salts was orders of magnitude higher...

  2. Communication: Near edge x-ray absorption fine structure spectroscopy of aqueous adenosine triphosphate at the carbon and nitrogen K-edges.

    Science.gov (United States)

    Kelly, Daniel N; Schwartz, Craig P; Uejio, Janel S; Duffin, Andrew M; England, Alice H; Saykally, Richard J

    2010-09-14

    Near edge x-ray absorption fine structure (NEXAFS) spectroscopy at the nitrogen and carbon K-edges was used to study the hydration of adenosine triphosphate in liquid microjets. The total electron yield spectra were recorded as a function of concentration, pH, and the presence of sodium, magnesium, and copper ions (Na(+)/Mg(2+)/Cu(2+)). Significant spectral changes were observed upon protonation of the adenine ring, but not under conditions that promote π-stacking, such as high concentration or presence of Mg(2+), indicating that NEXAFS is insensitive to the phenomenon. Intramolecular inner-sphere association of Cu(2+) did create observable broadening of the nitrogen spectrum, whereas outer-sphere association with Mg(2+) did not.

  3. Sequestering of Cu(II) from aqueous solution using cassava peel (Manihot esculenta)

    Energy Technology Data Exchange (ETDEWEB)

    Kosasih, Aline Natasia; Febrianto, Jonathan [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei 10607, Taiwan (China); Department of Chemical Engineering, Widya Mandala Surabaya Catholic University, Kalijudan 37, Surabaya 60114 (Indonesia); Sunarso, Jaka [School of Chemical Engineering, The University of Queensland, St. Lucia, QLD 4072 (Australia); Ju, Yi-Hsu [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei 10607, Taiwan (China); Indraswati, Nani [Department of Chemical Engineering, Widya Mandala Surabaya Catholic University, Kalijudan 37, Surabaya 60114 (Indonesia); Ismadji, Suryadi, E-mail: suryadi@mail.wima.ac.id [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei 10607, Taiwan (China); Department of Chemical Engineering, Widya Mandala Surabaya Catholic University, Kalijudan 37, Surabaya 60114 (Indonesia)

    2010-08-15

    Cassava peel is a prospective cheap biosorbent for metal ions sequestration. In this research, the ability of cassava peel to remove Cu(II) from aqueous solution was evaluated. Its physical characteristics were probed by nitrogen adsorption measurements and scanning electron microscopy while its biosorption mechanism was studied by Fourier Transform Infrared (FTIR), Scanning Electron Microscopy/Energy Dispersive using X-ray analysis-(SEM/EDX), X-ray mapping and X-ray Photoelectron Spectroscopy (XPS). Biosorption experiments were carried out isothermally at three different temperatures (30 deg. C, 45 deg. C and 60 deg. C) in a static mode. The maximum adsorption capacity (41.77 mg g{sup -1}) was attained at the highest temperature. The pH and particle size effects in relation to biosorption capacity were also discussed. In addition, Langmuir, Freundlich, Sips and Toth equations were tested for data correlation. Langmuir and Freundlich models were the best choices since they contained less parameter with equally good fitting performance in comparison to the other three parameters equations. For kinetic studies, sorption rates were better represented using a pseudo second-order expression in comparison to a more commonly used pseudo first-order equation. Also, thermodynamic variables showed that the process was spontaneous ({Delta}G < 0), endothermic ({Delta}H > 0) and irreversible ({Delta}S > 0).

  4. X-ray Crystallography Facility

    Science.gov (United States)

    2000-01-01

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

  5. X-Ray Exam: Hip

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Hip KidsHealth > For Parents > X-Ray Exam: Hip A A A What's in ... español Radiografía: cadera What It Is A hip X-ray is a safe and painless test that ...

  6. X-Ray Exam: Finger

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Finger KidsHealth > For Parents > X-Ray Exam: Finger A A A What's in ... español Radiografía: dedo What It Is A finger X-ray is a safe and painless test that ...

  7. X-Ray Exam: Foot

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Foot KidsHealth > For Parents > X-Ray Exam: Foot A A A What's in ... español Radiografía: pie What It Is A foot X-ray is a safe and painless test that ...

  8. X-Ray Exam: Wrist

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Wrist KidsHealth > For Parents > X-Ray Exam: Wrist A A A What's in ... español Radiografía: muñeca What It Is A wrist X-ray is a safe and painless test that ...

  9. X-Ray Exam: Ankle

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Ankle KidsHealth > For Parents > X-Ray Exam: Ankle A A A What's in ... español Radiografía: tobillo What It Is An ankle X-ray is a safe and painless test that ...

  10. X-Ray Exam: Pelvis

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Pelvis KidsHealth > For Parents > X-Ray Exam: Pelvis A A A What's in ... español Radiografía: pelvis What It Is A pelvis X-ray is a safe and painless test that ...

  11. X-Ray Exam: Forearm

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Forearm KidsHealth > For Parents > X-Ray Exam: Forearm A A A What's in ... español Radiografía: brazo What It Is A forearm X-ray is a safe and painless test that ...

  12. X-ray selected BALQSOs

    CERN Document Server

    Page, M J; Ceballos, M; Corral, A; Ebrero, J; Esquej, P; Krumpe, M; Mateos, S; Rosen, S; Schwope, A; Streblyanska, A; Symeonidis, M; Tedds, J A; Watson, M G

    2016-01-01

    We study a sample of six X-ray selected broad absorption line (BAL) quasi-stellar objects (QSOs) from the XMM-Newton Wide Angle Survey. All six objects are classified as BALQSOs using the classic balnicity index, and together they form the largest sample of X-ray selected BALQSOs. We find evidence for absorption in the X-ray spectra of all six objects. An ionized absorption model applied to an X-ray spectral shape that would be typical for non-BAL QSOs (a power law with energy index alpha=0.98) provides acceptable fits to the X-ray spectra of all six objects. The optical to X-ray spectral indices, alpha_OX, of the X-ray selected BALQSOs, have a mean value of 1.69 +- 0.05, which is similar to that found for X-ray selected and optically selected non-BAL QSOs of similar ultraviolet luminosity. In contrast, optically-selected BALQSOs typically have much larger alpha_OX and so are characterised as being X-ray weak. The results imply that X-ray selection yields intrinsically X-ray bright BALQSOs, but their X-ray sp...

  13. Zeolites as alcohol adsorbents from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Cekova Blagica

    2006-01-01

    Full Text Available The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

  14. Aqueous solution dispersement of carbon nanotubes

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2011-01-01

    Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

  15. Monte Carlo simulation of indirect damage to biomolecules irradiated in aqueous solution: The radiolysis of glycylglycine

    Energy Technology Data Exchange (ETDEWEB)

    Bolch, W.E.; Turner, J.E.; Yoshida, H.; Jacobson, K.B.; Hamm, R.N.; Wright, H.A.; Ritchie, R.H.; Klots, C.E.

    1988-07-01

    A Monte Carlo computer code is developed for simulating the radiolysis of glycylglycine in both oxygenated and deoxygenated aqueous solution. Second, this model is used to calculate the yields of various products in solutions irradiated either by 250-kVp X-rays or by /sup 60/Co gamma rays. Third, calculated product yields are compared to measured yields where available. The Monte Carlo computer codes used in this study are modified and extended versions of three existing simulation codes, written at the Oak Ridge National Laboratory (ORNL), which simulate irradiations of pure liquid water. The ORNL codes calculate the formation, diffusion, and reaction of free radicals and other species along charged-particle tracks in liquid water. As part of this research, these codes are extended to simulate irradiation of pure oxygenated water, oxygenated glycylglycine solutions, and deoxygenated glycylglycine solutions. 80 refs., 38 figs., 8 tabs.

  16. X-ray today

    Energy Technology Data Exchange (ETDEWEB)

    Neitzel, U. [Philips Medical Systems, Hamburg (Germany)

    2001-09-01

    The interest attracted by the new imaging modalities tends to overshadow the continuing importance of projection radiography and fluoroscopy. Nevertheless, projection techniques still represent by far the greatest proportion of diagnostic imaging examinations, and play an essential role in the growing number of advanced interventional procedures. This article describes some of the latest developments in X-ray imaging technology, using two products from the Philips range as examples: the Integris Allura cardiovascular system with 3D image reconstruction, and the BV Pulsera: a high-end, multi-functional mobile C-arm system with cardiac capabilities. (orig.)

  17. SMM x ray polychromator

    Science.gov (United States)

    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. The removal of phenol from aqueous solutions by adsorption using surfactant-modified bentonite and kaolinite

    Energy Technology Data Exchange (ETDEWEB)

    Alkaram, Uday F.; Mukhlis, Abduljabar A. [Department of Chemistry, College of Education, Ibn Al-Haitham, University of Baghdad, Baghdad (Iraq); Al-Dujaili, Ammar H., E-mail: ahdujaili@yahoo.com [Department of Chemistry, College of Education, Ibn Al-Haitham, University of Baghdad, Baghdad (Iraq)

    2009-09-30

    The natural bentonite (BC) and kaolinite (KC) were modified with two surfactant of hexadecyltrimethylammonium bromide (HDTMA) and phenyltrimethylammonium bromide (PTMA) to form four kinds of organic-modified clays, i.e., HDTMA-bentonite (BHM), HDTMA-kaolinite (KHM), PTMA-bentonite (KPM) and PTMA-kaolinite (KPM). The modified minerals were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and FT-IR spectroscopy. The surface areas were determined using methylene blue adsorption method. Cation-exchange capacity (CEC) was estimated using an ethylenediamine complex of copper method and the modifier loading was calculated from the total carbon analysis. The ability of raw and organo-modified clays to remove phenol from aqueous solutions has been carried out as a function of contact time, pH and temperatures using a batch technique. The removal of phenol from aqueous solutions by modified clays seems to be more effective than unmodified samples. The adsorption capacity was found to increase with increasing temperature indication that the adsorptions were endothermic. The adsorption of phenol onto these clays was found to be increased by increasing of pH value and the adsorption patterns data are correlated well by Langmuir and Freundlich isotherm models and that the adsorption is physical in nature. The experimental data fitted very well with the pseudo-second-order kinetic model. The thermodynamic study of adsorption process showed that the adsorption of phenol with these six adsorbents was carried out spontaneously, and the process was endothermic in nature.

  19. Novel magnetic Fe3O4@C nanoparticles as adsorbents for removal of organic dyes from aqueous solution.

    Science.gov (United States)

    Zhang, Zhengyong; Kong, Jilie

    2011-10-15

    The magnetic Fe(3)O(4)/C core-shell nanoparticles have been synthesized by a simple strategy and used as adsorbents for removal of organic dyes from aqueous solution. The resulting products are characterized by scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectra and Fourier transform infrared spectra (FTIR). Adsorption performances of the nanomaterial adsorbents are tested with removal of methylene blue (MB) and cresol red (CR) from aqueous solution. The effects of solution pH value, adsorption time and capacity of the nanocomposites have been fully investigated. The results reveal that the nanospheres can be easily manipulated by an external magnetic field with high separation efficiency. In addition, the process is clean and safe for purifying water pollution. The prepared Fe(3)O(4)/C complex nanomaterials could thus be used as promising adsorbents for the remove organic dyes, especially, cationic dye, from polluted water.

  20. OPTICAL PROPERTIES OF CARBAMIDE AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    E. V. Avramenko

    2016-03-01

    Full Text Available Subject of Research. The paper presents the results of measurements of refractometric properties (refractive index n, its temperature factor dn/dt and the ultraviolet spectral absorption in carbonic acid diamide aqueous solutions (carbamide depending on solid residue mass fraction md = 0-50 % and on temperaturet = 10-70 °C.Method of Research. Laboratory methods ofliquid-phase medium refractometry and ultraviolet spectrophotometry were applied for the research. We carried out computational modeling of electronic states spectrum for the carbonic acid diamide molecule and theoretical calculation of the fundamental electronic absorption of the molecule in the ultraviolet wavelenght region.Main Results. We have established that the solution concentration md has a nonlinear character and may be represented by the quadratic polynomial with the error Δn= ± 0,0005. We have shown the refractive indexdependence on temperature n(t changes in linear fashion att = 10-70 °C.At that, the inclination of lines n(t increases at the increase of md; so, the temperature factor dn/dt may be approximated by the quadratic polynomial. Transmission spectra of solutions in the spectral region λ= 225-760 nm have no special features except for the sharp edge in the short-wavelength region; the fundamental electronic absorptionis responsible for it. We have established that dispersion dependences of the refraction index n(λ;md in aqueous solutions of carbamide at λ= 360-760 nm and at md = 0-50 % may be calculated with the satisfactory error without additional adjustable parameters from the ultraviolet absorption data in terms of the one-dimentional oscillator Lorentz model.PracticalRelevance. Representedmeasurements of carbonic acid diamide aqueous solutions optical properties may be applied for the adjustment and calibration of commercial refractometers at processing lines of the AdBlue reagent manufacture for the selective catalytic reduction (SCR of motor transport

  1. Two step formation of metal aggregates by surface X-ray radiolysis under Langmuir monolayers: 2D followed by 3D growth

    Directory of Open Access Journals (Sweden)

    Smita Mukherjee

    2015-12-01

    Full Text Available In order to form a nanostructured metallic layer below a Langmuir monolayer, radiolysis synthesis was carried out in an adapted geometry that we call surface X-ray radiolysis. In this procedure, an X-ray beam produced by a synchrotron beamline intercepts the surface of an aqueous metal-ion solution covered by a Langmuir monolayer at an angle of incidence below the critical angle for total internal reflection. Underneath the organic layer, the X-ray beam induces the radiolytic synthesis of a nanostructured metal–organic layer whose ultrathin thickness is defined by the vertical X-ray penetration depth. We have shown that increasing the X-ray flux on the surface, which considerably enhances the kinetics of the silver layer formation, results in a second growth regime of silver nanocrystals. Here the formation of the oriented thin layer is followed by the appearance of a 3D powder of silver clusters.

  2. Spider Silks-Biomimetics Beyond Silk Fibers: Hydrogels, films & Adhesives from Aqueous Recombinant Spider Silk dopes: A Synchrotron X-Ray Nano-Structural Study

    Science.gov (United States)

    Sampath, Sujatha; Jones, Justin; Harris, Thomas; Lewis, Randolph

    2015-03-01

    With a combination of high strength and extensibility, spider silk's (SS) mechanical properties surpass those of any man made fiber. The superior properties are due to the primary protein composition and the complex hierarchical structural organization from nanoscale to macroscopic length scales. Considerable progress has been made to synthetically mimic the production of fibers based on SS proteins. We present synchrotron x-ray micro diffraction (SyXRD) results on new fibers and gels (hydrogels, lyogels) from recombinant SS protein water-soluble dopes. Novelty in these materials is two-fold: water based rather than widely used HFIP acid synthesis, makes them safe in medical applications (replacement for tendons & ligaments). Secondly, hydrogels morphology render them as excellent carriers for targeted drug delivery biomedical applications. SyXRD results reveal semi-crystalline structure with ordered beta-sheets and relatively high degree of axial orientation in the fibers, making them the closest yet to natural spider silks. SyXRD on the gels elucidate the structural transformations during the self-recovery process through mechanical removal and addition of water. Studies correlating the observed structural changes to mechanical properties are underway.

  3. X-ray scattering study of pike olfactory nerve: intensity of the axonal membrane, solution of the phase problem and electron density profile.

    Science.gov (United States)

    Luzzati, Vittorio; Vachette, Patrice; Benoit, Evelyne; Charpentier, Gilles

    2004-10-08

    Synchrotron radiation X-ray scattering experiments were performed on unmyelinated pike olfactory nerves. The difference between the meridional and the equatorial traces of the 2-D spectra yielded the 1-D equatorial intensity of the macromolecular components oriented with respect to the nerve: axonal membranes, microtubules and other cytoskeletal filaments. These 1-D spectra display a diffuse band typical of bilayer membranes and, at small s, a few sharper bands reminiscent of microtubules. All the spectra merge at large s. The intensity of the axonal membrane was determined via a noise analysis of the nerve-dependent spectra, involving also the notion that the thickness of the membrane is finite. The shape of the intensity function indicated that the electron density profile is not centrosymmetric. The knowledge of intensity and thickness paved the way to the electron density profile via an ab initio solution of the phase problem. An iterative procedure was adopted: (i) choose the lattice D of a 1-D pseudo crystal, interpolate the intensity at the points sh = h/D, adopt an arbitrary set of initial phases and compute the profile; (ii) determine the phases corresponding to this profile truncated by the thickness D/2; (iii) repeat the operation with the updated phases until a stable result is obtained. This iterative procedure was carried out for different D-values, starting in each case from randomly generated phases: stable results were obtained in less than 10,000 iterations. Most importantly, for D in the vicinity of 200 A, the overwhelming majority of the profiles were congruent with each other. These profiles were strongly asymmetric and otherwise typical of biological membranes.

  4. Density of aqueous solutions of CO2

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Julio E.

    2001-10-10

    In this report, we present a numerical representation for the partial molar volume of CO2 in water and the calculation of the corresponding aqueous solution density. The motivation behind this work is related to the importance of having accurate representations for aqueous phase properties in the numerical simulation of carbon dioxide disposal into aquifers as well as in geothermal applications. According to reported experimental data the density of aqueous solutions of CO2 can be as much as 2-3% higher than pure water density. This density variation might produce an influence on the groundwater flow regime. For instance, in geologic sequestration of CO2, convective transport mixing might occur when, several years after injection of carbon dioxide has stopped, the CO2-rich gas phase is concentrated at the top of the formation, just below an overlaying caprock. In this particular case the heavier CO2 saturated water will flow downward and will be replaced by water with a lesser CO2 content.

  5. Lead removal from aqueous solutions by a Tunisian smectitic clay.

    Science.gov (United States)

    Chaari, Islem; Fakhfakh, Emna; Chakroun, Salima; Bouzid, Jalel; Boujelben, Nesrine; Feki, Mongi; Rocha, Fernando; Jamoussi, Fakher

    2008-08-15

    The adsorption of Pb(2+) ions onto Tunisian smectite-rich clay in aqueous solution was studied in a batch system. Four samples of clay (AYD, AYDh, AYDs, AYDc) were used. The raw AYD clay was sampled in the Coniacian-Early Campanian of Jebel Aïdoudi in El Hamma area (South of Tunisia). AYDh and AYDs corresponds to AYD activated by 2.5 mol/l hydrochloric acid and 2.5 mol/l sulphuric acid, respectively. AYDc corresponds to AYD calcined at different temperatures (100, 200, 300, 400, 500 and 600 degrees C). The raw AYD clay was characterized by X-ray diffraction, chemical analysis, infrared spectroscopy and coupled DTA-TGA. Specific surface area of all the clay samples was determined from nitrogen adsorption isotherms. Preliminary adsorption tests showed that sulphuric acid and hydrochloric acid activation of raw AYD clay enhanced its adsorption capacity for Pb(2+) ions. However, the uptake of Pb(2+) by AYDs was very high compared to that by AYDh. This fact was attributed to the greater solubility of clay minerals in sulphuric acid compared to hydrochloric acid. Thermic activation of AYD clay reduced the Pb(2+) uptake as soon as calcination temperature reaches 200 degrees C. All these preliminary results were well correlated to the variation of the specific surface area of the clay samples. The ability of AYDs sample to remove Pb(2+) from aqueous solutions has been studied at different operating conditions: contact time, adsorbent amount, metal ion concentration and pH. Kinetic experiments showed that the sorption of lead ions on AYDs was very fast and the equilibrium was practically reached after only 20 min. The results revealed also that the adsorption of lead increases with an increase in the solution pH from 1 to 4.5 and then decreases, slightly between pH 4.5 and 6, and rapidly at pH 6.5 due to the precipitation of some Pb(2+) ions. The equilibrium data were analysed using Langmuir isotherm model. The maximum adsorption capacity (Q(0)) increased from 25 to 25

  6. Influence of thermal treatment on bentonite used as adsorbent for Cd, Pb, Zn retention from mono-solute and poly-solute aqueous solutions

    Directory of Open Access Journals (Sweden)

    Susana Yamila Martinez Stagnaro

    2012-08-01

    Full Text Available The retentions of Zn, Cd and Pb cations by one treated bentonite up to 750 °C were analyzed. The retentions were evaluated by using mono-and poly-solute aqueous solutions of such cations. The adsorptions were carried out in batch system at room temperature. The solid/liquid ratio was 2% wt.v-1. The solids were characterized by X-ray diffraction, thermal and chemical analyses. The Zn cation from mono- or polysolute-solutions was retained in higher amount than Cd and Pb cations in similar solution types by bentonite. The retentions were effective up to 450 °C calcined bentonite, after that, the retention capacity decreased in concordance with dehydroxylation of the structure of clay minerals.

  7. Cooperative protein structural dynamics of homodimeric hemoglobin linked to water cluster at subunit interface revealed by time-resolved X-ray solution scattering

    Directory of Open Access Journals (Sweden)

    Jong Goo Kim

    2016-03-01

    Full Text Available Homodimeric hemoglobin (HbI consisting of two subunits is a good model system for investigating the allosteric structural transition as it exhibits cooperativity in ligand binding. In this work, as an effort to extend our previous study on wild-type and F97Y mutant HbI, we investigate structural dynamics of a mutant HbI in solution to examine the role of well-organized interfacial water cluster, which has been known to mediate intersubunit communication in HbI. In the T72V mutant of HbI, the interfacial water cluster in the T state is perturbed due to the lack of Thr72, resulting in two less interfacial water molecules than in wild-type HbI. By performing picosecond time-resolved X-ray solution scattering experiment and kinetic analysis on the T72V mutant, we identify three structurally distinct intermediates (I1, I2, and I3 and show that the kinetics of the T72V mutant are well described by the same kinetic model used for wild-type and F97Y HbI, which involves biphasic kinetics, geminate recombination, and bimolecular CO recombination. The optimized kinetic model shows that the R-T transition and bimolecular CO recombination are faster in the T72V mutant than in the wild type. From structural analysis using species-associated difference scattering curves for the intermediates, we find that the T-like deoxy I3 intermediate in solution has a different structure from deoxy HbI in crystal. In addition, we extract detailed structural parameters of the intermediates such as E-F distance, intersubunit rotation angle, and heme-heme distance. By comparing the structures of protein intermediates in wild-type HbI and the T72V mutant, we reveal how the perturbation in the interfacial water cluster affects the kinetics and structures of reaction intermediates of HbI.

  8. Surface characterisation of ethylene-propylene-diene rubber upon exposure to aqueous acidic solution

    DEFF Research Database (Denmark)

    Mitra, S.; Ghanbari-Siahkali, Afshin; Kingshott, P.

    2006-01-01

    Two types of pure ethylene propylene diene rubbers were exposed to two different acids for varying period of time. Surface characterisation was carried out using X-ray photoelectron spectroscopy (XPS). Two EPDM rubbers selected for this study were comparable in co-monomer compositions...... but significantly different with respect to molar mass and the presence of long chain branching. Both rubbers contained 5-ethylidene-2-norbomene (ENB) as diene. Solution cast films of pure EPDM samples were exposed in two different acidic solutions, viz. chromosulphuric (Cr (VI)/H2SO4) and sulphuric acid (H2SO4......) (20%, v/v) at ambient temperature from 1 to 12 weeks. XPS analysis indicated that several oxygenated species were formed on the surface of both rubbers after exposure. It was postulated from the XPS analyses that both aqueous acidic solutions attacked the olefinic double bonds (C=C) of ENB...

  9. An in situ electrochemical soft X-ray spectromicroscopy investigation of Fe galvanically coupled to Au.

    Science.gov (United States)

    Gianoncelli, A; Kaulich, B; Kiskinova, M; Prasciolu, M; Urzo, B D; Bozzini, B

    2011-06-01

    In this paper we report a pioneering electrochemical study of the galvanic coupling of Au and Fe in neutral aqueous solutions containing sulphate and fluoride ions, carried out by synchrotron-based in situ soft X-ray imaging and X-ray absorption microspectroscopy. The investigation was performed at the TwinMic X-ray Microscopy station at Elettra synchrotron facility combining X-ray imaging with μ-XAS with sub-micron lateral resolution. Using a purposely developed model thin-layer wet cell the morphology and chemical evolution of Fe electrodes in contact with aqueous solutions containing Na2SO4 and NaF have been investigated. The obtained results shed light on fundamental aspects regarding stability of Fe-based metallic bipolar plates in different electrochemical environments, an important issue for durability of polymer-electrolyte fuel cells. Imaging morphological features typical of the relevant electrochemical processes with chemical contrast, yields details on the spatial distribution and speciation of Fe resulting from corrosion of the Fe electrodes in the working fuel cells.

  10. Aqueous Solution Vessel Thermal Model Development II

    Energy Technology Data Exchange (ETDEWEB)

    Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-28

    The work presented in this report is a continuation of the work described in the May 2015 report, “Aqueous Solution Vessel Thermal Model Development”. This computational fluid dynamics (CFD) model aims to predict the temperature and bubble volume fraction in an aqueous solution of uranium. These values affect the reactivity of the fissile solution, so it is important to be able to calculate them and determine their effects on the reaction. Part A of this report describes some of the parameter comparisons performed on the CFD model using Fluent. Part B describes the coupling of the Fluent model with a Monte-Carlo N-Particle (MCNP) neutron transport model. The fuel tank geometry is the same as it was in the May 2015 report, annular with a thickness-to-height ratio of 0.16. An accelerator-driven neutron source provides the excitation for the reaction, and internal and external water cooling channels remove the heat. The model used in this work incorporates the Eulerian multiphase model with lift, wall lubrication, turbulent dispersion and turbulence interaction. The buoyancy-driven flow is modeled using the Boussinesq approximation, and the flow turbulence is determined using the k-ω Shear-Stress-Transport (SST) model. The dispersed turbulence multiphase model is employed to capture the multiphase turbulence effects.

  11. Leaching of lead from zinc leach residue in acidic calcium chloride aqueous solution

    Science.gov (United States)

    Wang, Le; Mu, Wen-ning; Shen, Hong-tao; Liu, Shao-ming; Zhai, Yu-chun

    2015-05-01

    A process with potentially reduced environmental impacts and occupational hazards of lead-bearing zinc plant residue was studied to achieve a higher recovery of lead via a cost-effective and environmentally friendly process. This paper describes an optimization study on the leaching of lead from zinc leach residue using acidic calcium chloride aqueous solution. Six main process conditions, i.e., the solution pH value, stirring rate, concentration of CaCl2 aqueous solution, liquid-to-solid (L/S) ratio, leaching temperature, and leaching time, were investigated. The microstructure and components of the residue and tailing were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). On the basis of experimental results, the optimum reaction conditions were determined to be a solution pH value of 1, a stirring rate of 500 r·min-1, a CaCl2 aqueous solution concentration of 400 g·L-1, a liquid-to-solid mass ratio of 7:1, a leaching temperature of 80°C, and a leaching time of 45 min. The leaching rate of lead under these conditions reached 93.79%, with an iron dissolution rate of 19.28%. Silica did not take part in the chemical reaction during the leaching process and was accumulated in the residue.

  12. Synthesis of 8-(dimethylamino)-1-naphthyllithium etherate. Its structure in the solid (X-ray) and in Solution (7Li and 1H NMR)

    NARCIS (Netherlands)

    Koten, G. van; Jastrzebski, J.T.B.H.; Goubitz, K.; Arlen, C.; Pfeffer, M.

    1983-01-01

    The reaction of Bu{4}Li{4} with 4 molar equivalents of 1-(dimethylamino)naphthalene in diethyl ether affords novel 8-(dimethylamino)-1-naphthyllithium. Its molecular structure (X-ray) consists of two 8-(dimethylamino)-1-naphthyl groups each 3 center-2 electron bonded via C(1) to two lithium atoms an

  13. Hybrid Silk Fibers Dry-Spun from Regenerated Silk Fibroin/Graphene Oxide Aqueous Solutions.

    Science.gov (United States)

    Zhang, Chao; Zhang, Yaopeng; Shao, Huili; Hu, Xuechao

    2016-02-10

    Regenerated silk fibroin (RSF)/graphene oxide (GO) hybrid silk fibers were dry-spun from a mixed dope of GO suspension and RSF aqueous solution. It was observed that the presence of GO greatly affect the viscosity of RSF solution. The RSF/GO hybrid fibers showed from FTIR result lower β-sheet content compared to that of pure RSF fibers. The result of synchrotron radiation wide-angle X-ray diffraction showed that the addition of GO confined the crystallization of silk fibroin (SF) leading to the decrease of crystallinity, smaller crystallite size, and new formation of interphase zones in the artificial silks. Synchrotron radiation small-angle X-ray scattering also proved that GO sheets in the hybrid silks and blended solutions were coated with a certain thickness of interphase zones due to the complex interaction between the two components. A low addition of GO, together with the mesophase zones formed between GO and RSF, enhanced the mechanical properties of hybrid fibers. The highest breaking stress of the hybrid fibers reached 435.5 ± 71.6 MPa, 23% improvement in comparison to that of degummed silk and 72% larger than that of pure RSF silk fiber. The hybrid RSF/GO materials with good biocompatibility and enhanced mechanical properties may have potential applications in tissue engineering, bioelectronic devices, or energy storage.

  14. Topological X-Rays Revisited

    Science.gov (United States)

    Lynch, Mark

    2012-01-01

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

  15. X-ray instrumentation for SR beamlines

    CERN Document Server

    Kovalchuk, M V; Zheludeva, S I; Aleshko-Ozhevsky, O P; Arutynyan, E H; Kheiker, D M; Kreines, A Y; Lider, V V; Pashaev, E M; Shilina, N Y; Shishkov, V A

    2000-01-01

    The main possibilities and parameters of experimental X-ray stations are presented: 'Protein crystallography', 'X-ray structure analysis', 'High-precision X-ray optics', 'X-ray crystallography and material science', 'X-ray topography', 'Photoelectron X-ray standing wave' that are being installed at Kurchatov SR source by A.V. Shubnikov Institute of Crystallography.

  16. X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

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

  17. X-ray Fluorescence Sectioning

    CERN Document Server

    Cong, Wenxiang

    2012-01-01

    In this paper, we propose an x-ray fluorescence imaging system for elemental analysis. The key idea is what we call "x-ray fluorescence sectioning". Specifically, a slit collimator in front of an x-ray tube is used to shape x-rays into a fan-beam to illuminate a planar section of an object. Then, relevant elements such as gold nanoparticles on the fan-beam plane are excited to generate x-ray fluorescence signals. One or more 2D spectral detectors are placed to face the fan-beam plane and directly measure x-ray fluorescence data. Detector elements are so collimated that each element only sees a unique area element on the fan-beam plane and records the x-ray fluorescence signal accordingly. The measured 2D x-ray fluorescence data can be refined in reference to the attenuation characteristics of the object and the divergence of the beam for accurate elemental mapping. This x-ray fluorescence sectioning system promises fast fluorescence tomographic imaging without a complex inverse procedure. The design can be ad...

  18. Soft X-ray optics

    CERN Document Server

    Spiller, Eberhard A

    1993-01-01

    This text describes optics mainly in the 10 to 500 angstrom wavelength region. These wavelengths are 50 to 100 times shorter than those for visible light and 50 to 100 times longer than the wavelengths of medical x rays or x-ray diffraction from natural crystals. There have been substantial advances during the last 20 years, which one can see as an extension of optical technology to shorter wavelengths or as an extension of x-ray diffraction to longer wavelengths. Artificial diffracting structures like zone plates and multilayer mirrors are replacing the natural crystals of x-ray diffraction.

  19. Speciation in aqueous solutions of nitric acid.

    Science.gov (United States)

    Hlushak, S; Simonin, J P; De Sio, S; Bernard, O; Ruas, A; Pochon, P; Jan, S; Moisy, P

    2013-02-28

    In this study, speciation in aqueous solutions of nitric acid at 25 °C was assessed in two independent ways. First, Raman experiments were carried out and interpreted in terms of free nitrate ions, ion pairs and neutral HNO(3) molecules. In parallel, a model was developed to account for the formation of these two kinds of pairs. It was based on an extension of the binding mean spherical approximation (BiMSA), or associative MSA (AMSA), in which the size and the charge of the ions in the chemical pair may differ from those of the free ions. A simultaneous fit of the osmotic coefficient and of the proportion of free ions (obtained from Raman spectroscopy experiments) led to an estimation of the speciation in nitric acid solutions. The result obtained using this procedure was compared with the estimation obtained from the Raman experiments.

  20. Multistep nucleation of nanocrystals in aqueous solution

    Science.gov (United States)

    Loh, N. Duane; Sen, Soumyo; Bosman, Michel; Tan, Shu Fen; Zhong, Jun; Nijhuis, Christian A.; Král, Petr; Matsudaira, Paul; Mirsaidov, Utkur

    2017-01-01

    The nucleation and growth of solids from solutions impacts many natural processes and is fundamental to applications in materials engineering and medicine. For a crystalline solid, the nucleus is a nanoscale cluster of ordered atoms that forms through mechanisms still poorly understood. In particular, it is unclear whether a nucleus forms spontaneously from solution via a single- or multiple-step process. Here, using in situ electron microscopy, we show how gold and silver nanocrystals nucleate from supersaturated aqueous solutions in three distinct steps: spinodal decomposition into solute-rich and solute-poor liquid phases, nucleation of amorphous nanoclusters within the metal-rich liquid phase, followed by crystallization of these amorphous clusters. Our ab initio calculations on gold nucleation suggest that these steps might be associated with strong gold-gold atom coupling and water-mediated metastable gold complexes. The understanding of intermediate steps in nuclei formation has important implications for the formation and growth of both crystalline and amorphous materials.

  1. Aqueous Solutions of Ionic Liquids: Microscopic Assembly.

    Science.gov (United States)

    Vicent-Luna, Jose Manuel; Dubbeldam, David; Gómez-Álvarez, Paula; Calero, Sofia

    2016-02-01

    Aqueous solutions of ionic liquids are of special interest, due to the distinctive properties of ionic liquids, in particular, their amphiphilic character. A better understanding of the structure-property relationships of such systems is hence desirable. One of the crucial molecular-level interactions that influences the macroscopic behavior is hydrogen bonding. In this work, we conduct molecular dynamics simulations to investigate the effects of ionic liquids on the hydrogen-bond network of water in dilute aqueous solutions of ionic liquids with various combinations of cations and anions. Calculations are performed for imidazolium-based cations with alkyl chains of different lengths and for a variety of anions, namely, [Br](-), [NO3](-), [SCN](-) [BF4](-), [PF6](-), and [Tf2N](-). The structure of water and the water-ionic liquid interactions involved in the formation of a heterogeneous network are analyzed by using radial distribution functions and hydrogen-bond statistics. To this end, we employ the geometric criterion of the hydrogen-bond definition and it is shown that the structure of water is sensitive to the amount of ionic liquid and to the anion type. In particular, [SCN](-) and [Tf2N](-) were found to be the most hydrophilic and hydrophobic anions, respectively. Conversely, the cation chain length did not influence the results.

  2. X-Ray Attenuation Cell

    Energy Technology Data Exchange (ETDEWEB)

    Ryutov, D.; Toor, A.

    2000-03-03

    To minimize the pulse-to-pulse variation, the LCLS FEL must operate at saturation, i.e. 10 orders of magnitude brighter spectral brilliance than 3rd-generation light sources. At this intensity, ultra-high vacuums and windowless transport are required. Many of the experiments, however, will need to be conducted at a much lower intensity thereby requiring a reliable means to reduce the x-ray intensity by many orders of magnitude without increasing the pulse-to-pulse variation. In this report we consider a possible solution for controlled attenuation of the LCLS x-ray radiation. We suggest using for this purpose a windowless gas-filled cell with the differential pumping. Although this scheme is easily realizable in principle, it has to be demonstrated that the attenuator can be made short enough to be practical and that the gas loads delivered to the vacuum line of sight (LOS) are acceptable. We are not going to present a final, optimized design. Instead, we will provide a preliminary analysis showing that the whole concept is robust and is worth further study. The spatial structure of the LCLS x-ray pulse at the location of the attenuator is shown in Fig. 1. The central high-intensity component, due to the FEL, has a FWHM of {approx}100 {micro}m. A second component, due to the undulator's broad band spontaneous radiation is seen as a much lower intensity ''halo'' with a FWHM of 1 mm. We discuss two versions of the attenuation cell. The first is directed towards a controlled attenuation of the FEL up to the 4 orders of magnitude in the intensity, with the spontaneous radiation halo being eliminated by collimators. In the second version, the spontaneous radiation is not sacrificed but the FEL component (as well as the first harmonic of the spontaneous radiation) gets attenuated by a more modest factor up to 100. We will make all the estimates assuming that the gas used in the attenuator is Xenon and that the energy of the FEL is 8.25 keV. At

  3. Structural and Functional Models for the Dinuclear Copper Active Site in Catechol Oxidases: Syntheses, X-ray Crystal Structures, Magnetic and Spectral Properties, and X-ray Absorption Spectroscopic Studies in Solid State and in Solution.

    Science.gov (United States)

    Zippel, Frank; Ahlers, Friedhelm; Werner, Rüdiger; Haase, Wolfgang; Nolting, Hans-Friedrich; Krebs, Bernt

    1996-05-22

    Two novel tridentate dinucleating ligands containing benzimidazole were prepared, 1,3-bis(2-benzimidazolyl)-2-propanol (Hbbp, 1) and 1,5-bis(2-benzimidazolyl)-3-pentanol (Hbbpen, 2). Their complexing properties toward copper were studied in order to obtain structural and functional models for catechol oxidases. Syntheses and crystal structures of dinuclear Cu(II) complexes derived from these ligands are reported. [Cu(2)bbp(2)](ClO(4))(2).2MeOH, 3, crystallizes in the triclinic space group P&onemacr; with the following unit cell parameters: a = 7.702(3) Å, b = 10.973(6) Å, c = 12.396(6) Å, alpha = 100.59(4) degrees, beta = 99.02(4) degrees, gamma = 98.90(4) degrees, V = 998.7(8) Å(3), and Z = 1. [Cu(2)bbpen(2)](ClO(4))(2).3MeOH, 4, crystallizes in the orthorhombic space group Pccn, with the following unit cell parameters: a = 17.478(9) Å, b = 18.795(8) Å, c = 13.888(6) Å, V = 4562.2(4) Å(3), and Z = 4. Magnetic susceptibility measurements in the temperature ranges 4.6-459 K (3) and 4.6-425 K (4) indicate an antiferromagnetic coupling between the Cu(II) centers of both complexes. In order to determine the structures of the complexes in solution, XAS spectra (EXAFS and XANES) were recorded in the solid state and in solution. The interpretation of these data, including multiple scattering calculations, together with UV-vis titrations, shows that the complexes have the same structure in the crystalline state as well as in methanolic solution. Complex 4 is able to oxidize 3,5-di-tert-butylcatechol (3,5-DTBC) to the quinone (catecholase activity). This reaction was also studied by XAS and UV-vis spectroscopy. These measurements reveal the reduction of Cu(II) to Cu(I) accompanied by a decrease of the coordination number.

  4. Terahertz absorption of dilute aqueous solutions.

    Science.gov (United States)

    Heyden, Matthias; Tobias, Douglas J; Matyushov, Dmitry V

    2012-12-21

    Absorption of terahertz (THz) radiation by aqueous solutions of large solutes reports on the polarization response of their hydration shells. This is because the dipolar relaxation of the solute is dynamically frozen at these frequencies, and most of the solute-induced absorption changes, apart from the expulsion of water, are caused by interfacial water. We propose a model expressing the dipolar response of solutions in terms of a single parameter, the interface dipole moment induced in the interfacial water by electromagnetic radiation. We apply this concept to experimental THz absorption of hydrated sugars, amino acids, and proteins. None of the solutes studied here follow the expectations of dielectric theories, which predict a negative projection of the interface dipole on the external electric field. We find that this prediction is not able to describe the available experimental data, which instead suggests a nearly zero interface dipole for sugars and a more diverse pattern for amino acids. Hydrophobic amino acids, similarly to sugars, give rise to near zero interface dipoles, while strongly hydrophilic ones are best described by a positive projection of the interface dipole on the external field. The sign of the interface dipole is connected to the slope of the absorption coefficient with the solute concentration. A positive slope, implying an increase in the solution polarity relative to water, mirrors results frequently reported for protein solutions. We therefore use molecular dynamics simulations of hydrated glucose and lambda repressor protein to calculate the interface dipole moments of these solutes and the concentration dependence of the THz absorption. The absorption at THz frequencies increases with increasing solute concentration in both cases, implying a higher polarity of the solution compared to bulk water. The structure of the hydration layer, extracted from simulations, is qualitatively similar in both cases, with spatial correlations

  5. Heterogeneous nucleation of aspartame from aqueous solutions

    Science.gov (United States)

    Kubota, Noriaki; Kinno, Hiroaki; Shimizu, Kenji

    1990-03-01

    Waiting times, the time from the instant of quenching needed for a first nucleus to appear, were measured at constant supercoolings for primary nucleation of aspartame (α-L-aspartyl-L-phenylalanine methylester) from aqueous solutions, which were sealed into glass ampoules (solution volume = 3.16 cm 3). Since the waiting time became shorter by filtering the solution prior to quenching, the nucleation was concluded to be heterogeneously induced. The measured waiting time consisted of two parts: time needed for the nucleus to grow to a detactable size (growth time) and stochastic time needed for nucleation (true waiting time). The distribution of the true waiting time, is well explained by a stochastic model, in which nucleation is regarded to occur heterogeneously and in a stochastic manner by two kinds of active sites. The active sites are estimated to be located on foreign particles in which such elements as Si, Al and Mg were contained. The amount of each element is very small in the order of magnitude of ppb (mass basis) of the whole solution. The growth time was correlated with the degree of supercooling.

  6. Crystallization, Preliminary X-ray Diffraction and Structure Solution of MosA, a Dihydrodipicolinate Synthase from Sinorhizobium Meliloti L5-30

    Energy Technology Data Exchange (ETDEWEB)

    Leduc,Y.; Phenix, C.; Puttick, J.; Nienaber, K.; Palmer, D.; Delbaere, L.

    2006-01-01

    The structure of MosA, a dihydrodipicolinate synthase and reported methyltransferase from Sinorhizobium meliloti, has been solved using molecular replacement with Escherichia coli dihydrodipicolinate synthase as the model. A crystal grown in the presence of pyruvate diffracted X-rays to 2.3 Angstroms resolution using synchrotron radiation and belonged to the orthorhombic space group C2221, with unit-cell parameters a = 69.14, b = 138.87, c = 124.13 Angstroms.

  7. Glass-to-cryogenic-liquid transitions in aqueous solutions suggested by crack healing.

    Science.gov (United States)

    Kim, Chae Un; Tate, Mark W; Gruner, Sol M

    2015-09-22

    Observation of theorized glass-to-liquid transitions between low-density amorphous (LDA) and high-density amorphous (HDA) water states had been stymied by rapid crystallization below the homogeneous water nucleation temperature (∼235 K at 0.1 MPa). We report optical and X-ray observations suggestive of glass-to-liquid transitions in these states. Crack healing, indicative of liquid, occurs when LDA ice transforms to cubic ice at 160 K, and when HDA ice transforms to the LDA state at temperatures as low as 120 K. X-ray diffraction study of the HDA to LDA transition clearly shows the characteristics of a first-order transition. Study of the glass-to-liquid transitions in nanoconfined aqueous solutions shows them to be independent of the solute concentrations, suggesting that they represent an intrinsic property of water. These findings support theories that LDA and HDA ice are thermodynamically distinct and that they are continuously connected to two different liquid states of water.

  8. Transformation and destabilization of graphene oxide in reducing aqueous solutions containing sulfide.

    Science.gov (United States)

    Fu, Heyun; Qu, Xiaolei; Chen, Wei; Zhu, Dongqiang

    2014-12-01

    The colloidal stability of carbon nanomaterials is a key factor controlling their fate and bioavailability in natural aquatic systems. The authors report that graphene oxide nanoparticles could be destabilized in reducing aqueous solutions containing a low concentration (0.5 mM) of sulfide, a naturally occurring reductant. Spectroscopic characterization using combined X-ray photoelectron, Fourier-transform infrared, X-ray diffraction, and Raman analyses revealed that the surface oxygen-containing groups (mainly epoxy groups) of graphene oxide were significantly reduced after reacting with sodium sulfide. The destabilization of graphene oxide was likely caused by the enhanced surface hydrophobicity of the reduced graphene oxide, whereas electrostatic repulsion played a minimal role. Solution pH was found to affect both the deoxygenation process and the aggregation behavior of graphene oxide. Coexisting humic acid reduced the reaction efficiency and stabilized graphene oxide through steric hindrance. These findings suggest for the first time that the colloidal behavior of carbon nanomaterials might change drastically when they enter natural reducing environments containing sulfide such as anaerobic aquifers and sediments.

  9. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... bone absorbs much of the radiation while soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air ...

  10. X-Ray Diffraction Apparatus

    Science.gov (United States)

    Blake, David F. (Inventor); Bryson, Charles (Inventor); Freund, Friedmann (Inventor)

    1996-01-01

    An x-ray diffraction apparatus for use in analyzing the x-ray diffraction pattern of a sample is introduced. The apparatus includes a beam source for generating a collimated x-ray beam having one or more discrete x-ray energies, a holder for holding the sample to be analyzed in the path of the beam, and a charge-coupled device having an array of pixels for detecting, in one or more selected photon energy ranges, x-ray diffraction photons produced by irradiating such a sample with said beam. The CCD is coupled to an output unit which receives input information relating to the energies of photons striking each pixel in the CCD, and constructs the diffraction pattern of photons within a selected energy range striking the CCD.

  11. Focusing X-Ray Telescopes

    Science.gov (United States)

    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.

  12. X-Ray Tomographic Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. Preparation and characterization of regenerated fiber from the aqueous solution of Bombyx mori cocoon silk fibroin

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Zhenghua [Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Department of Application Engineering, ZheJiang Vocational College of Economic and Trade, HangZhou, ZheJiang 310018 (China); Imada, Takuzo [Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Asakura, Tetsuo, E-mail: asakura@cc.tuat.ac.jp [Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan)

    2009-10-15

    The regenerated silk fibers with high strength and high biodegradability were prepared from the aqueous solution of Bombyx mori silk fibroin from cocoons with wet spinning method. Although the tensile strength of the regenerated silk fibroin fiber, 210 MPa is still half of the strength of native silk fiber, the diameter of the fiber is about 100 {mu}m which is suitable for monofilament of suture together with high biodegradability. The high concentration (30%, w/v) of the aqueous solution of the silk fibroin which corresponds to the high concentration in the middle silkgland of silkworm was obtained. This was performed by adjusting the pH of the aqueous solution to 10.4 which corresponds to pK{sub a} value of the OH group of Tyr residues in the silk fibroin. The mixed solvent, methanol/acetic acid (7:3 in volume ratio) was used as coagulant solvent for preparing the regenerated fiber. The structural change of silk fibroin fiber by stretching was monitored with both {sup 13}C solid state NMR and X-ray diffraction methods, indicating that the high strength of the fiber is related with the long-range orientation of the silk fibroin chain with {beta}-sheet structure.

  14. Functionalized polymers for binding to solutes in aqueous solutions

    Science.gov (United States)

    Smith, Barbara F.; Robison, Thomas W.

    2006-11-21

    A functionalized polymer for binding a dissolved molecule in an aqueous solution is presented. The polymer has a backbone polymer to which one or more functional groups are covalently linked. The backbone polymer can be such polymers as polyethylenimine, polyvinylamine, polyallylamine, and polypropylamine. These polymers are generally water-soluble, but can be insoluble when cross-linked. The functional group can be for example diol derivatives, polyol derivatives, thiol and dithiol derivatives, guest-host groups, affinity groups, beta-diphosphonic acids, and beta-diamides

  15. Instrumental Characterization Of Coir PITH By XRD, FTIR and SEM After Radium Adsorption From Aqueous Solution Under The Presence Of Humic Acids

    Science.gov (United States)

    Laili, Zalina; Omar, Muhamat; Yasir, Muhamad Samudi; Ibrahim, Mohd Zaidi; Yahaya, Mohd Yusri; Murshidi, Julie Andrianny

    2010-01-01

    Adsorption interactions of radium (Ra) ions onto coir pith (CP) under the presence of humic acid (HA) in the aqueous solution were investigated using X-ray diffraction (XRD), Fourier Transform Infrared Spectrophotometer (FTIR) and Scanning Electron Microscopy (SEM) techniques. XRD, IR and SEM characterization of the CP has revealed differences in the native CP and Ra ions loaded CP under the presence of HA in the aqueous solution. The X-Ray patterns showed that crystalline structure of the loaded CP exhibited a decrease in crystalline structure at around 49°-51° compared with unloaded CP. Characterization by IR revealed that participation of some surface functional groups during the Ra adsorption. SEM images for the morphological studies showed that there were slightly changes of the CP surfaces after the adsorption process.

  16. Bioactive and Antibacterial Glass Powders Doped with Copper by Ion-Exchange in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Marta Miola

    2016-05-01

    Full Text Available In this work, two bioactive glass powders (SBA2 and SBA3 were doped with Cu by means of the ion-exchange technique in aqueous solution. SBA2 glass was subjected to the ion-exchange process by using different Cu salts (copper(II nitrate, chloride, acetate, and sulphate and concentrations. Structural (X-ray diffraction-XRD, morphological (Scanning Electron Microscopy-SEM, and compositional (Energy Dispersion Spectrometry-EDS analyses evidenced the formation of crystalline phases for glasses ion-exchanged in copper(II nitrate and chloride solutions; while the ion-exchange in copper(II acetate solutions lead to the incorporation of higher Cu amount than the ion-exchange in copper(II sulphate solutions. For this reason, the antibacterial test (inhibition halo towards S. aureus was performed on SBA2 powders ion-exchanged in copper(II acetate solutions and evidenced a limited antibacterial effect. A second glass composition (SBA3 was developed to allow a greater incorporation of Cu in the glass surface; SBA3 powders were ion-exchanged in copper(II acetate solutions (0.01 M and 0.05 M. Cu-doped SBA3 powders showed an amorphous structure; morphological analysis evidenced a rougher surface for Cu-doped powders in comparison to the undoped glass. EDS and X-ray photoelectron spectroscopy (XPS confirmed the Cu introduction as Cu(II ions. Bioactivity test in simulated body fluid (SBF showed that Cu introduction did not alter the bioactive behaviour of the glass. Finally, inhibition halo test towards S. aureus evidenced a good antimicrobial effect for glass powders ion-exchanged in copper(II acetate solutions 0.05 M.

  17. X-ray monitoring optical elements

    Energy Technology Data Exchange (ETDEWEB)

    Stoupin, Stanislav; Shvydko, Yury; Katsoudas, John; Blank, Vladimir D.; Terentyev, Sergey A.

    2016-12-27

    An X-ray article and method for analyzing hard X-rays which have interacted with a test system. The X-ray article is operative to diffract or otherwise process X-rays from an input X-ray beam which have interacted with the test system and at the same time provide an electrical circuit adapted to collect photoelectrons emitted from an X-ray optical element of the X-ray article to analyze features of the test system.

  18. X-ray diagnostics for TFTR

    Energy Technology Data Exchange (ETDEWEB)

    von Goeler, S.; Hill, K.W.; Bitter, M.

    1982-12-01

    A short description of the x-ray diagnostic preparation for the TFTR tokamak is given. The x-ray equipment consists of the limiter x-ray monitoring system, the soft x-ray pulse-height-analysis-system, the soft x-ray imaging system and the x-ray crystal spectrometer. Particular attention is given to the radiation protection of the x-ray systems from the neutron environment.

  19. "Switchable water": aqueous solutions of switchable ionic strength.

    Science.gov (United States)

    Mercer, Sean M; Jessop, Philip G

    2010-04-26

    "Salting out" is a standard method for separating water-soluble organic compounds from water. In this method, adding a large amount of salt to the aqueous solution forces the organic compound out of the aqueous phase. However, the method can not be considered sustainable because it creates highly salty water. A greener alternative would be a method that allows reversible salting out. Herein, we describe aqueous solutions of switchable ionic strength. Aqueous solutions of a diamine in water have essentially zero ionic strength but are converted by CO(2) into solutions of high ionic strength. The change is reversible. Application to the reversible salting out of THF from water is described.

  20. Characteristics and mechanisms of Ni(Ⅱ) removal from aqueous solution by Chinese loess

    Institute of Scientific and Technical Information of China (English)

    王艳; 唐晓武; 王恒宇

    2015-01-01

    Nickel is a toxic heavy metal among trace elements which has a detrimental impact on living organisms. There is growing need of finding an economic and effective solution for Ni(Ⅱ) immobilization in environments. Chinese loess was selected as adsorbent to remove Ni(Ⅱ) from aqueous solution. Adsorbent dosage, reaction time, solute concentration, temperature, and solution p H also have influences on efficiency of Ni(Ⅱ) removal. The monolayer adsorption capacity of loess towards Ni(Ⅱ) is determined to be about 15.61 mg/g. High temperature and p H favor the removal of Ni(Ⅱ) using Chinese loess soil and the optimal dosage of loess is determined to be 10 g/L. The kinetics and adsorption isotherms of the adsorption process can be best-fitted with the pseudo second order kinetics and Langmuir isothermal model, respectively. The thermodynamic analysis reveals that the adsorption process is spontaneous, endothermic and the system disorder increases with duration. Nickel ions can be removed with the removal efficiency of 98.5% at p H greater than or equal to 9.7. Further studies on loess and Ni(Ⅱ) laden loess(using X-Ray diffraction, Fourier transform infrared spectroscopy) and Ni(Ⅱ) species distribution at various p H have been conducted to discuss the adsorption mechanism. Loess soils in China have proven to be a potential adsorbent for Ni(Ⅱ) removal from aqueous solutions.

  1. Characteristics and mechanisms of Ni(II) removal from aqueous solution by Chinese loess

    Institute of Scientific and Technical Information of China (English)

    王艳; 唐晓武; 王恒宇

    2015-01-01

    Nickel is a toxic heavy metal among trace elements which has a detrimental impact on living organisms. There is growing need of finding an economic and effective solution for Ni(II) immobilization in environments. Chinese loess was selected as adsorbent to remove Ni(II) from aqueous solution. Adsorbent dosage, reaction time, solute concentration, temperature, and solution pH also have influences on efficiency of Ni(II) removal. The monolayer adsorption capacity of loess towards Ni(II) is determined to be about 15.61 mg/g. High temperature and pH favor the removal of Ni(II) using Chinese loess soil and the optimal dosage of loess is determined to be 10 g/L. The kinetics and adsorption isotherms of the adsorption process can be best-fitted with the pseudo second order kinetics and Langmuir isothermal model, respectively. The thermodynamic analysis reveals that the adsorption process is spontaneous, endothermic and the system disorder increases with duration. Nickel ions can be removed with the removal efficiency of 98.5% at pH greater than or equal to 9.7. Further studies on loess and Ni(II) laden loess (using X-Ray diffraction, Fourier transform infrared spectroscopy) and Ni(II) species distribution at various pH have been conducted to discuss the adsorption mechanism. Loess soils in China have proven to be a potential adsorbent for Ni(II) removal from aqueous solutions.

  2. Removal of Evans Blue and Yellow thiazole dyes from aqueous solution by Mg-Al-CO3 Layered Double Hydroxides as anion-exchanger

    OpenAIRE

    Mohamed Bouraada; Louis Charles de Ménorval; Hassiba Bessaha

    2014-01-01

    Mg-Al-CO3 Layered double hydroxide (LDH) was prepared by co-precipitation method at constant pH, and subsequently used to remove Evans Blue (EB) and Yellow thiazole (YT) dyes from aqueous solutions. The obtained material was characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis and BET. The kinetic and equilibrium aspects of sorption of the anionic dyes from aqueous solution by Mg-Al-CO3 were investigated in batch mode. The sorp...

  3. Semiconductor X-ray detectors

    CERN Document Server

    Lowe, Barrie Glyn

    2014-01-01

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

  4. Phase Changes of Monosulfoaluminate in NaCl Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Seyoon Yoon

    2016-05-01

    Full Text Available Monosulfoaluminate (Ca4Al2(SO4(OH12∙6H2O plays an important role in anion binding in Portland cement by exchanging its original interlayer ions (SO42− and OH− with chloride ions. In this study, scanning transmission X-ray microscope (STXM, X-ray absorption near edge structure (XANES spectroscopy, and X-ray diffraction (XRD were used to investigate the phase change of monosulfoaluminate due to its interaction with chloride ions. Pure monosulfoaluminate was synthesized and its powder samples were suspended in 0, 0.1, 1, 3, and 5 M NaCl solutions for seven days. At low chloride concentrations, a partial dissolution of monosulfoaluminate formed ettringite, while, with increasing chloride content, the dissolution process was suppressed. As the NaCl concentration increased, the dominant mechanism of the phase change became ion exchange, resulting in direct phase transformation from monosulfoaluminate to Kuzel’s salt or Friedel’s salt. The phase assemblages of the NaCl-reacted samples were explored using thermodynamic calculations and least-square linear combination (LC fitting of measured XANES spectra. A comprehensive description of the phase change and its dominant mechanism are discussed.

  5. High-pressure x-ray diffraction study of U sub x La sub 1 sub - sub x S solid solution

    CERN Document Server

    Bihan, T L; Idiri, M; Heathman, S; Lindbaum, A

    2002-01-01

    X-ray diffraction measurements under pressure have been performed on seven different compositions in the U sub x La sub 1 sub - sub x S system (x = 0, 0.08, 0.40, 0.50, 0.60, 0.80, 1). All the compounds have the same structure (NaCl type) at ambient pressure, but show different behaviours under pressure. A transformation into the CsCl-type structure is only observed for x = 0.60, B sub 0 approx 100 GPa) and in the transition pressure (approx 30 GPa for low-uranium-content compounds and from 45 to 80 GPa for high concentrations).

  6. Small angle x-ray studies reveal that Aspergillus niger glucoamylase has a defined extended conformation and can form dimers in solution

    DEFF Research Database (Denmark)

    Jørgensen, Anders Dysted; Nøhr, Jane; Kastrup, Jette Sandholm

    2008-01-01

    The industrially important glucoamylase 1 is an exo-acting glycosidase with substrate preference for alpha-1,4 and alpha-1,6 linkages at non-reducing ends of starch. It consists of a starch binding and a catalytic domain interspersed by a highly glycosylated polypeptide linker. The linker function...... is poorly understood and structurally undescribed, and data regarding domain organization and intramolecular functional cooperativity are conflicting or non-comprehensive. Here, we report a combined small angle x-ray scattering and calorimetry study of Aspergillus niger glucoamylase 1, glucoamylase 2, which...

  7. Formation of hydroxyapatite in various aqueous solutions

    Science.gov (United States)

    Sturgeon, Jacqueline Lee

    Hydroxyapatite (HAp), Ca10(PO4)6(OH) 2, is important in the field of biomaterials as it is the mineral component of bones and teeth. Biological apatites do not maintain an exact composition and are usually calcium-deficient, represented as Ca(10- x)(HPO 4)x(PO4)(6-x)(OH)(2-x), where x ranges from 0 to 1, with various ion substitutions. Formation of calcium-deficient hydroxyapatites (CDHAp) from solid calcium phosphate precursor materials was performed at physiologic temperature (37°C) in a variety of aqueous solutions. Two cement systems were utilized in these experiments: tetralcium phosphate (TetCP) with dicalcium phosphate anhydrous (DCPA) and beta-tricalcium phosphate (beta-TCP). The kinetics, solution chemistry, phase evolution, and microstructure of the developed apatites were analyzed as appropriate. Reaction of beta-TCP in ammonium fluoride solutions formed HAp substituted with fluoride and calculated to be deficient in calcium. A new ratio of TetCP to DCPA was used with solutions of sodium bicarbonate to form a calcium-deficient carbonate hydroxyapatite. The capacity for sodium dihydrogen phosphate to buffer pH increases and enhance reaction kinetics in this system was also explored. Formation of a highly crystalline CDHAp was achieved by hydrolyzing beta-TCP in water for extended time periods. Lattice parameters were among the features characterized for this apatite. The hydrolysis of beta-TCP in phosphate buffered saline (PBS) and simulated body fluids (SBF) was also investigated; use of SBF was found to completely inhibit formation of HAp in this system while reaction in PBS was slow in comparison to water. The effects of filler materials on the mechanical properties of a calcium phosphate cement were examined using the TetCP/DCPA system. Dense aggregates were not found to decrease compressive strength in comparison to the cement alone. The use of aggregates was found to improve the compressive strength of cement formed using NaHCO3 solution as a

  8. Removal of methyl orange from aqueous solutions through adsorption by calcium aluminate hydrates.

    Science.gov (United States)

    Zhang, Ping; Wang, Tianqi; Qian, Guangren; Wu, Daishe; Frost, Ray L

    2014-07-15

    Methyl orange (MO) is a kind of anionic dye and widely used in industry. In this study, tricalcium aluminate hydrates (Ca-Al-LDHs) are used as an adsorbent to remove methyl orange (MO) from aqueous solutions. The resulting products were studied by X-ray diffraction (XRD), infrared spectroscopy (MIR), thermal analysis (TG-DTA) and scanning electron microscope (SEM). The XRD results indicated that the MO molecules were successfully intercalated into the tricalcium aluminate hydrates, with the basal spacing of Ca-Al-LDH expanding to 2.48 nm. The MIR spectrum for CaAl-MO-LDH shows obvious bands assigned to the N=N, N=H stretching vibrations and S=O, SO3(-) group respectively, which are considered as marks to assess MO(-) ion intercalation into the interlayers of LDH. The overall morphology of CaAl-MO-LDH displayed a "honey-comb" like structure, with the adjacent layers expanded.

  9. Self-assembly of highly crystalline spherical BiVO 4 in aqueous solutions

    Science.gov (United States)

    Yang, Tao; Xia, Dingguo

    2009-10-01

    Spherical bismuth vanadate particles are self-assembled from aqueous Bi(NO 3) 3 and NH 4VO 3 solutions by adjusting pH and tuning the amount of surfactant sodium dodecyl sulfate (SDS) via facile hydrothermal method. The BiVO 4 samples were characterized by X-ray diffraction (XRD) and the peaks suited well with the pure phase monoclinic scheelite BiVO 4. Field emission scanning electron microscopy (SEM) showed the average size of the spherical particles was 5 μm and the assembling stages in the hydrothermal synthesis process were recorded. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) revealed the nanoparticles were single crystal. FT-IR spectroscopy test results demonstrated there was no SDS left in the samples. The mechanism of the self-assembling has also been proposed.

  10. Study on the adsorption of heavy metal ions from aqueous solution on modified SBA-15

    Directory of Open Access Journals (Sweden)

    Liliana Giraldo

    2013-01-01

    Full Text Available Amino-functionalized SBA-15 mesoporous silica was prepared, characterized, and used as an adsorbent for heavy metal ions. The organic - inorganic hybrid material was obtained by a grafting procedure using SBA-15 silica with 3-aminopropyl-triethoxysilane and bis(2,4,4-trimethylpentyl phosphinic acid (Cyanex 272, respectively. The structure and physicochemical properties of the materials were characterized by means of elemental analysis, X-ray diffraction (XRD, nitrogen adsorption - desorption, thermogravimetric analysis, FTIR spectroscopy and immersion calorimetry. The organic functional groups were successfully grafted onto the SBA-15 surface and the ordering of the support was not affected by the chemical modification. The behavior of the grafted solids was investigated for the adsorption of heavy metal ions from aqueous solutions. The hybrid materials showed high adsorption capacity and high selectivity for zinc ions. Other ions, such as cooper and cobalt were absorbed by the modified SBA-15 material.

  11. First Observation of Electron Transfer Mediated Decay in Aqueous Solutions: A Novel Probe of Ion Pairing

    CERN Document Server

    Unger, I; Thürmer, S; Aziz, E F; Cederbaum, L S; Muchová, E; Slavíček, P; Winter, B; Kryzhevoi, N V

    2016-01-01

    A major goal of many spectroscopic techniques is to provide comprehensive information on the local chemical environment. Electron transfer mediated decay (ETMD) is a sensitive probe of the environment since it is actively involved in this non-local radiationless decay process through electron and energy transfer steps. We report the first experimental observation of ETMD in the liquid phase. Using liquid-jet X-ray photoelectron spectroscopy we explore LiCl aqueous solution, and detect low-energy electrons unambiguously emerging from the ETMD processes of core-ionized Li+. We interpret the experimental results with molecular dynamics and high-level ab initio calculations. By considering various solvation-structure models we show that both water molecules and Cl- anions can participate in ETMD, with each process having its characteristic spectral fingerprint. Different ion associations lead to different spectral shapes. The potential application of the unique sensitivity of the ETMD spectroscopy to the local hy...

  12. Removal of Lead (II Ions from Aqueous Solutions onto Activated Carbon Derived from Waste Biomass

    Directory of Open Access Journals (Sweden)

    Murat Erdem

    2013-01-01

    Full Text Available The removal of lead (II ions from aqueous solutions was carried out using an activated carbon prepared from a waste biomass. The effects of various parameters such as pH, contact time, initial concentration of lead (II ions, and temperature on the adsorption process were investigated. Energy Dispersive X-Ray Spectroscopy (EDS analysis after adsorption reveals the accumulation of lead (II ions onto activated carbon. The Langmuir and Freundlich isotherm models were applied to analyze equilibrium data. The maximum monolayer adsorption capacity of activated carbon was found to be 476.2 mg g−1. The kinetic data were evaluated and the pseudo-second-order equation provided the best correlation. Thermodynamic parameters suggest that the adsorption process is endothermic and spontaneous.

  13. Rapid synthesis of CdSe nanocrystals in aqueous solution at room temperature

    Indian Academy of Sciences (India)

    Yilin Wang; Jian Ping Lu; Zhang Fa Tong

    2010-10-01

    Water-soluble thioglycolic acid-capped CdSe nanocrystals (NCs) were prepared in aqueous solution at room temperature. We investigated the effects of pH values on the fluorescence intensity of the as-prepared CdSe NCs, and discussed the influence of the initial pH values on the fluorescence property. Their mean diameter was estimated to be 1.9 nm depending on the initial pH values in the preparation, the photoluminescence quantum yield could reach as high as 1.9%, almost comparable to the CdSe NCs prepared by an organometallic route. Finally, the products were characterized by Fourier transform infrared spectrometry (FTIR), atomic force microscope (AFM) and X-ray powder diffraction (XRD). AFM image showed that the NCs were ball-shaped with good dispersibility. XRD analysis disclosed that the CdSe NCs were of cubic zinc-blended structure.

  14. Formation of hydrated layers in PMMA thin films in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Akers, Peter W. [School of Chemical Sciences, University of Auckland, Auckland (New Zealand); Nelson, Andrew R.J. [The Bragg Institute, Australian Nuclear Science and Technology Organisation, Menai, NSW (Australia); Williams, David E. [School of Chemical Sciences, University of Auckland, Auckland (New Zealand); MacDiarmid Institute of Advanced Materials and Nanotechnology, Wellington (New Zealand); McGillivray, Duncan J., E-mail: d.mcgillivray@auckland.ac.nz [School of Chemical Sciences, University of Auckland, Auckland (New Zealand); MacDiarmid Institute of Advanced Materials and Nanotechnology, Wellington (New Zealand)

    2015-10-30

    Graphical abstract: - Highlights: • Homogeneous thin PMMA films prepared on Si/SiOx substrates and measured in air and water. • Reproducible formation of highly hydrated layer containing 50% water at the PMMA/SiOx interface. • When heated the films swell at 50 °C without loss of material. • Upon re-cooling to 25 °C the surface roughens and material is lost. - Abstract: Neutron reflectometry (NR) measurements have been made on thin (70–150 Å) poly(methylmethacrylate) (PMMA) films on Si/SiOx substrates in aqueous conditions, and compared with parameters measured using ellipsometry and X-Ray reflectometry (XRR) on dry films. All techniques show that the thin films prepared using spin-coating techniques were uniform and had low roughness at both the silicon and subphase interfaces, and similar surface energetics to thicker PMMA films. In aqueous solution, NR measurements at 25 °C showed that PMMA forms a partially hydrated layer at the SiOx interface 10 Å under the film, while the bulk film remains intact and contains around 4% water. Both the PMMA film layer and the sublayer showed minimal swelling over a period of 24 h. At 50 °C, PMMA films in aqueous solution roughen and swell, without loss of PMMA material at the surface. After cooling back to 25 °C, swelling and roughening increases further, with loss of material from the PMMA layer.

  15. Removal of Pb(II) ions from aqueous solutions on few-layered graphene oxide nanosheets.

    Science.gov (United States)

    Zhao, Guixia; Ren, Xuemei; Gao, Xing; Tan, Xiaoli; Li, Jiaxing; Chen, Changlun; Huang, Yuying; Wang, Xiangke

    2011-11-07

    Few-layered graphene oxide (FGO) was synthesized from graphite by using the modified Hummers method, and was characterized by scanning electron microscopy, atomic force microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. The prepared FGO was used to adsorb Pb(II) ions from aqueous solutions. The abundant oxygen-containing groups on the surfaces of FGO played an important role in Pb(II) ion adsorption on FGO. The adsorption of Pb(II) ions on FGO was dependent on pH values and independent of ionic strength. The adsorption of Pb(II) ions on FGO was mainly dominated by strong surface complexation. From the adsorption isotherms, the maximum adsorption capacities (C(smax)) of Pb(II) ions on FGO calculated from the Langmuir model were about 842, 1150, and 1850 mg g(-1) at 293, 313, and 333 K, respectively, higher than any currently reported. The FGO had the highest adsorption capacities of today's nanomaterials. The thermodynamic parameters calculated from the temperature dependent adsorption isotherms indicated that the adsorption of Pb(II) ions on FGO was a spontaneous and endothermic process.

  16. Cathodic electrochemiluminescence of luminol in aqueous solutions based on C-doped oxide covered titanium electrode

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jian; Zhao Rongrong; Xu Meizhu [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry, Fuzhou University, 523 Gongye Road, Fuzhou, Fujian 350002 (China); Chen Guonan, E-mail: gnchen@fzu.edu.c [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry, Fuzhou University, 523 Gongye Road, Fuzhou, Fujian 350002 (China)

    2010-12-15

    In the present work, a novel sensor for luminol electrochemiluminescence (ECL) was constructed on the base of a C-doped titanium oxide amorphous semiconductor electrode. The morphology, structural and electrochemical properties of the electrode was characterized by X-Ray diffraction, X-Ray photoelectron spectroscopy and electrochemical methods. The ECL behavior of luminol excited by hot electrons injected from C-doped oxide film-covered electrodes in aqueous medium has been investigated in B-R buffer solution (pH = 9) when linear sweep cyclic voltammetry (CV) was applied. Two ECL peaks were observed at -1.0 V (vs. Ag/AgCl, reduction process) and -0.75 V (vs. Ag/AgCl, oxidation process). The possible mechanism was discussed. The C-doped Ti oxide electrode shows excellent properties for sensitive determination of luminol with good reproducibility and stability. The linear response of luminol was in the range of 1 x 10{sup -8} to 9 x 10{sup -8} mol/L with the detection limit of 3 x 10{sup -9} mol/L (S/N = 3). Since luminol is one of the most useful ECL probe, many bioactive compounds which can be labeled by luminol are able to be detected by using the proposed method.

  17. Solution structure of human plasma fibronectin using small-angle X-ray and neutron scattering at physiological pH and ionic strength

    Energy Technology Data Exchange (ETDEWEB)

    Sjoeberg, B.P.; Pap, S.; Osterlund, E.; Osterlund, K.; Vuento, M.; Kjems, J.

    1987-06-01

    Human plasma fibronectin has been investigated at physiological pH and ionic strength, by using small-angle X-ray and neutron scattering techniques. The results indicate that the molecule is disc shaped with an axial ratio of about 1:10. In fact, an ellipsoid of revolution with semiaxes a = 1.44 nm and b = c = 13.8 nm is in agreement with the experimental scattering data, and can also fully explain the rather extreme hydrodynamic parameters reported for fibronectin. The X-ray data gave a radius of gyration of 8.9 nm and a molecular weight of 510,000, whereas the neutron data gave slightly larger values, 9.5 nm and 530,000, respectively. From the volume of the best fitting ellipsoid we obtain a degree of hydration of 0.61 g H/sub 2/O/g protein (dry weight). Neutron data, recorded at different D/sub 2/O concentrations in the solvent, gave a match point of 43% D/sub 2/O, which indicates that approximately 80% of the hydrogens bound to oxygen and nitrogen are exchangeable.

  18. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... are easily accessible and are frequently compared to current x-ray images for diagnosis and disease management. ... of North America, Inc. (RSNA). To help ensure current and accurate information, we do not permit copying ...

  19. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... patients and physicians. Because x-ray imaging is fast and easy, it is particularly useful in emergency ... diagnosis and treatment of the individual patient's condition. Ultrasound imaging, which uses sound waves instead of ionizing ...

  20. X-Ray Assembler Data

    Data.gov (United States)

    U.S. Department of Health & Human Services — Federal regulations require that an assembler who installs one or more certified components of a diagnostic x-ray system submit a report of assembly. This database...

  1. CELESTIAL X-RAY SOURCES.

    Science.gov (United States)

    sources, (4) the physical conditions in the pulsating x-ray source in the Crab Nebula , and (5) miscellaneous related topics. A bibliography of all work performed under the contract is given. (Author)

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... ionizing radiation to produce pictures of any bone in the body. It is commonly used to diagnose ... bone x-ray makes images of any bone in the body, including the hand, wrist, arm, elbow, ...

  3. Bone X-Ray (Radiography)

    Science.gov (United States)

    ... bony fragments following treatment of a fracture. guide orthopedic surgery, such as spine repair/fusion, joint replacement ... A portable x-ray machine is a compact apparatus that can be taken to the patient in ...

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... these links. About Us | Contact Us | FAQ | Privacy | Terms of Use | Links | Site Map Copyright © 2017 Radiological ...

  5. Accelerator x-ray sources

    CERN Document Server

    Talman, Richard

    2007-01-01

    This first book to cover in-depth the generation of x-rays in particle accelerators focuses on electron beams produced by means of the novel Energy Recovery Linac (ERL) technology. The resulting highly brilliant x-rays are at the centre of this monograph, which continues where other books on the market stop. Written primarily for general, high energy and radiation physicists, the systematic treatment adopted by the work makes it equally suitable as an advanced textbook for young researchers.

  6. X-ray fluorescence holography

    CERN Document Server

    Hayashi, K; Takahashi, Y

    2003-01-01

    X-ray fluorescence holography (XFH) is a new structural analysis method of determining a 3D atomic arrangement around fluorescing atoms. We developed an XFH apparatus using advanced X-ray techniques and succeeded in obtaining high-quality hologram data. Furthermore, we introduced applications to the structural analysis of a thin film and the environment around dopants and, discussed the quantitative analysis of local lattice distortion. (author)

  7. 21 CFR 524.1200b - Kanamycin ophthalmic aqueous solution.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Kanamycin ophthalmic aqueous solution. 524.1200b Section 524.1200b Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... § 524.1200b Kanamycin ophthalmic aqueous solution. (a) Specifications. The drug, which is in an...

  8. Acetic acid extraction from aqueous solutions using fatty acids

    NARCIS (Netherlands)

    IJmker, H.M.; Gramblicka, M.; Kersten, S.R.A.; Ham, van der A.G.J.; Schuur, B.

    2014-01-01

    A major challenge for production of acetic acid via bio-based routes is cost-effective concentration and purification of the acetic acid from the aqueous solutions, for which liquid–liquid extraction is a possible method. A main challenge in extraction of acetic acid from dilute aqueous solutions is

  9. Analysis by synchrotron X-ray radiography of convection effects on the dynamic evolution of the solid-liquid interface and on solute distribution during the initial transient of solidification

    Energy Technology Data Exchange (ETDEWEB)

    Bogno, A., E-mail: abdoul-aziz.bogno@im2np.fr [Aix Marseille Universite, Campus Saint-Jerome, Case 142, 13397 Marseille Cedex 20 (France); CNRS, UMR 6242, Campus Saint-Jerome, Case 142, 13397 Marseille Cedex 20 (France); Nguyen-Thi, H. [Aix Marseille Universite, Campus Saint-Jerome, Case 142, 13397 Marseille Cedex 20 (France); CNRS, UMR 6242, Campus Saint-Jerome, Case 142, 13397 Marseille Cedex 20 (France); Buffet, A. [ESRF, Avenue des Martyrs, BP 220, 38048 Grenoble Cedex (France); Reinhart, G.; Billia, B.; Mangelinck-Noel, N.; Bergeon, N. [Aix Marseille Universite, Campus Saint-Jerome, Case 142, 13397 Marseille Cedex 20 (France); CNRS, UMR 6242, Campus Saint-Jerome, Case 142, 13397 Marseille Cedex 20 (France); Baruchel, J. [ESRF, Avenue des Martyrs, BP 220, 38048 Grenoble Cedex (France); Schenk, T. [LPM - ENSMN, Parc de Saurupt, 54042 Nancy Cedex (France)

    2011-06-15

    In situ monitoring of the initial transient of directional solidification was carried out by means of synchrotron X-ray radiography. Experiments with Al-4 wt.% Cu alloy samples were performed on beamline ID19 of the European Synchrotron Radiation Facility (ESRF) in a dedicated Bridgman-type furnace. X-ray radiography enabled a detailed analysis of the evolution over time of the solid-liquid interface macroscopic shape in interaction with convection in the melt. Lateral solute segregation induced by fluid flow resulted in a significant deformation of the solid-liquid interface. The time-dependent velocity of the solidification front was determined at different abscissa values along the curved interface during the solidification process, from the growth phase with a smooth interface to the onset of morphological instability. Further, using a novel quantitative image analysis technique we were able to measure longitudinal solute profiles in the melt during the initial transient. Solutal length was then deduced as well as concentration in the melt, both at the interface and far away from it. The influence of convection on growth velocity and the characteristic parameters of the solute boundary layer are discussed, and a comparison with the Warren and Langer model is also presented.

  10. X-ray laser; Roentgenlaser

    Energy Technology Data Exchange (ETDEWEB)

    Samuelsen, Emil J.; Breiby, Dag W.

    2009-07-01

    X-ray is among the most important research tools today, and has given priceless contributions to all disciplines within the natural sciences. State of the art in this field is called XFEL, X-ray Free Electron Laser, which may be 10 thousand million times stronger than the x-rays at the European Synchrotron Radiation Facility in Grenoble. In addition XFEL has properties that allow the study of processes which previously would have been impossible. Of special interest are depictions on atomic- and molecular level by the use of x-ray holographic methods, and being able to study chemical reactions in nature's own timescale, the femtosecond. Conclusion: The construction of x-ray lasers is a natural development in a scientific field which has an enormous influence on the surrounding society. While the discovery of x-ray was an important breakthrough in itself, new applications appear one after the other: Medical depiction, dissemination, diffraction, DNA and protein structures, synchrotron radiation and tomography. There is reason to believe that XFEL implies a technological leap as big as the synchrotrons some decades ago. As we are now talking about studies of femtosecond and direct depiction of chemical reactions, it is obvious that we are dealing with a revolution to come, with extensive consequences, both scientifically and culturally. (EW)

  11. X-Rays, Pregnancy and You

    Science.gov (United States)

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

  12. Structure of aqueous sodium perchlorate solutions.

    Science.gov (United States)

    General, Ignacio J; Asciutto, Eliana K; Madura, Jeffry D

    2008-12-01

    Salt solutions have been the object of study of many scientists through history, but one of the most important findings came along when the Hofmeister series were discovered. Their importance arises from the fact that they influence the relative solubility of proteins, and solubility is directly related to one of today's holy grails: protein folding. In this work we characterize one of the more-destabilizing salts in the series, sodium perchlorate, by studying it as an aqueous solution at various concentrations ranging from 0.08 to 1.60 mol/L. Molecular dynamics simulations at room temperature permitted a detailed study of the organization of solvent and cosolvent, in terms of its radial distribution functions, along with the study of the structure of hydrogen bonds in the ions' solvation shells. We found that the distribution functions have some variations in their shape as concentration changes, but the position of their peaks is mostly unaffected. Regarding water, the most salient fact is the noticeable (although small) change in the second hydration shell and even beyond, especially for g(O(w)***O(w)), showing that the locality of salt effects should not be restricted to considerations of only the first solvation shell. The perturbation of the second shell also appears in the study of the HB network, where the difference between the number of HBs around a water molecule and around the Na(+) cation gets much smaller as one goes from the first to the second solvation shell, yet the difference is not negligible. Nevertheless, the effect of the ions past their first hydration shell is not enough to make a noticeable change in the global HB network. The Kirkwood-Buff theory of liquids was applied to our system, in order to calculate the activity derivative of the cosolvent. This coefficient, along with a previously calculated preferential binding, allowed us to establish that if a folded AP peptide is immersed in the studied solution, becoming the solute, then

  13. Fluoride Adsorption by Pumice from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Amir Hossein Mahvi

    2012-01-01

    Full Text Available Drinking water provides many vital elements for the human body, but the presence of some dissolved elements more than permissible concentration can endanger human health. Among the dissolved elements in drinking water, fluoride is noticeable, because both the very low or very high concentrations have adverse health impacts such as dental caries. Therefore, fluoride concentration should be kept in acceptable levels. In this study Pumice was used for fluoride removal. It was found that Fluoride sorption kinetic was fitted by pseudo-second-order model. The maximum sorption capacity of Pumice was found to be 13.51 mg/g at laboratory temperature (24°C. Maximum sorption study occurred at pH= 3. Results of Isotherm showed the fluoride sorption has been well fitted with Freundlich isotherm model. This study has demonstrated that Pumice can be used as effective adsorbents for fluoride removal from aqueous solutions. The adsorbent prepared in this study was cheap and efficient in removal of fluoride than other adsorbents.

  14. Functionalization of Microcrystalline Cellulose with N,N-dimethyldodecylamine for the Removal of Congo Red Dye from an Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Dongying Hu

    2014-08-01

    Full Text Available Microcrystalline cellulose (MCC was functionalized with quaternary amine groups for use as an adsorbent to remove Congo Red dye (CR from aqueous solution. The ultrasonic pretreatment of MCC was investigated during its functionalization. Characterization was conducted using infrared spectroscopy (FT-IR, X-ray photoelectron spectroscopy (XPS, X-ray diffraction (XRD, and scanning electron microscopy (SEM. The batch adsorption of the functionalized MCC was studied to evaluate the effects of dye concentration, pH of solution, temperature, and NaCl concentration on the adsorption CR. The adsorbent (FM-1 obtained using ultrasonic pretreatment of MCC under 10.8 kJ•g–1 exhibited an adsorption capacity of 304 mg•g–1 at initial pH under a dose of 0.1 g•L–1 and initial concentration of 80 mg•L–1. After functionalization, the FT-IR and XPS results indicated that the quaternary amine group was successfully grafted onto the cellulose, the surface was transformed to be coarse and porous, and the crystalline structure of the original cellulose was disrupted. FM-1 has been shown to be a promising and efficient adsorbent for the removal of CR from an aqueous solution.

  15. Removal of lead(II) and copper(II) from aqueous solution using foitite from Linshou mine in Hebei, China.

    Science.gov (United States)

    He, Dengliang; Yin, Guangfu; Dong, Faqin; Liu, Laibao; Tan, Xiaoli; He, Wangyang

    2011-01-01

    Foitite from Linshou mine in China's Hebei province was investigated as an adsorbent to remove Pb(II) and Cu(II) from aqueous solution. The results showed that foitite can readily remove heavy metal ions from aqueous solution. The data shows that the metal uptake for Pb(II) increases rapidly, accounting for 74.47% when contact time was 2 min. In contrast to Pb(ll), there was a worse capability for adsorption of Cu(II). In the first 4 min, the metal uptake accounted for 34.7%. According to the analytical results obtained from X-ray diffraction, laser Raman spectrum, X-ray energy dispersive spectrometer, and Zeta potential, the removal mechanism of Pb(II) and Cu(II) by using foitite can be explained as following: firstly, the existence of an electrostatic field around foitite particles can attract heavy metal ions and consequently combine heavy metal ions with OH; secondly, heavy metal ions in the solution are exchanged with the Fe3+ and Al3+ in the foitite.

  16. Self-Assembly of Amphiphilic Block Copolymers Containing Poly(n-octadecyl acrylate) Block in Aqueous Solution

    Energy Technology Data Exchange (ETDEWEB)

    Akiba, Isamu; Akino, Yusuke; Masunaga, Hiroyasu; Sakurai, Kazuo, E-mail: akiba@env.kitakyu-u.ac.jp

    2010-11-15

    Synchrotron small-angle X-ray scattering (SAXS) experiments were carried out for poly(acrylic acid)-block-poly(n-octadecyl acrylate) (PAA-b-PODA) and PAA-b-PODA-b-PAA micelles in aqueous solutions. SAXS results indicated that PAA-b-PODA and PAA-b-PODA-b-PAA formed core-shell micelles with disk-like morphology below melting temperature of PODA in aqueous solutions. The thickness of PAA-b-PODA (diblock copolymer) micelle was larger than that of PAA-b-PODA-b-PAA (triblock copolymer) micelle. The difference of sizes between these micelles was related to difference of molecular architectures of PAA-b-PODA and PAA-b-PODA-b-PAA. PAA-b-PODA micelle showed morphological transition from disk to spherical shape with elevating temperature. On the contrary, PAA-b-PODA-b-PAA micelle maintained disk-like shape above melting temperature, although enlargement of micelle thickness is caused.

  17. Self-Assembly of Amphiphilic Block Copolymers Containing Poly(n-octadecyl acrylate) Block in Aqueous Solution

    Science.gov (United States)

    Akiba, Isamu; Akino, Yusuke; Masunaga, Hiroyasu; Sakurai, Kazuo

    2010-11-01

    Synchrotron small-angle X-ray scattering (SAXS) experiments were carried out for poly(acrylic acid)-block-poly(n-octadecyl acrylate) (PAA-b-PODA) and PAA-b-PODA-b-PAA micelles in aqueous solutions. SAXS results indicated that PAA-b-PODA and PAA-b-PODA-b-PAA formed core-shell micelles with disk-like morphology below melting temperature of PODA in aqueous solutions. The thickness of PAA-b-PODA (diblock copolymer) micelle was larger than that of PAA-b-PODA-b-PAA (triblock copolymer) micelle. The difference of sizes between these micelles was related to difference of molecular architectures of PAA-b-PODA and PAA-b-PODA-b-PAA. PAA-b-PODA micelle showed morphological transition from disk to spherical shape with elevating temperature. On the contrary, PAA-b-PODA-b-PAA micelle maintained disk-like shape above melting temperature, although enlargement of micelle thickness is caused.

  18. Manufacturing of patterned ZnO films with application for photoinitiated decolorization of malachite green in aqueous solutions

    Indian Academy of Sciences (India)

    Nina V Kaneva; Georgi G Yordanov; Ceco D Dushkin

    2010-04-01

    Patterned thin films, ZnO, are successfully prepared on glass substrates by the sol–gel method using dip-coating technique. The films, formed of ZnO nanocrystallites with hexagonal crystal structure, are characterized by means of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The as obtained ZnO films are studied with respect to photo-initiated bleaching of malachite green in aqueous solutions. The bleaching process is investigated at various initial concentrations of malachite green in the aqueous solutions by using ZnO films of different thicknesses. The obtained results are promising for the development of ZnO photocatalysts by the sol–gel method.

  19. X-ray absorption spectroscopy of diluted system by undulator photon source and multi-element solid-state detector

    CERN Document Server

    Tanida, H

    2001-01-01

    In order to measure the extended X-ray absorption fine structure (EXAFS) spectrum of an ultra-diluted system, an optics and detector control system for a synchrotron radiation beamline is developed. The undulator gap width is continuously tuned to obtain the maximum X-ray photon flux during the energy scan for the EXAFS measurement. A piezoelectric translator optimizes the parallelism of the double crystal in a monochromator at each measurement point to compensate for mechanical errors of the monochromator, resulting in a smooth and intense X-ray photon flux during the measurement. For a detection of a weak fluorescence signal from diluted samples, a 19-element solid-state detector and digital signal processor are used. A K-edge EXAFS spectrum of iron in a myoglobin aqueous solution with a concentration of 5.58 parts per million was obtained by this system.

  20. X-ray Damage to the Mn4Ca Complex in Single Crystals ofPhotosystem II: A Case Study for Metalloprotein Crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Junko; Kern, Jan; Irrgang, Klaus-Dieter; Latimer, Matthew; Bergmann, Uwe; Glatzel, Pieter; Pushkar, Yulia; Biesiadka, Jacek; Loll,Bernhard; Sauer, Kenneth; Messinger, Johannes; Zouni, Athina; Yachandra,Vittal K.

    2005-06-21

    X-ray absorption spectroscopy was used to measure the damage caused by exposure to X-rays to the Mn4Ca active site in single crystals of photosystem II, as a function of dose and energy of X-rays, temperature, and time. These studies reveal that the conditions used for structure determination by X-ray crystallography cause serious damage specifically to the metal-site structure. The X-ray absorption spectra show that the structure changes from one that is characteristic of a high-valent Mn4(III2,IV2) oxo-bridged Mn4Ca cluster, to that of Mn(II) in aqueous solution. This damage to the metal site occurs at a dose that is more than an order of magnitude lower than that resulting in loss of diffractivity, and commonly considered safe for protein crystallography. These results establish the first quantitative X-ray dose parameters applicable to redox-active metallo-proteins. This case study shows that a careful evaluation of the structural intactness of the active sites by spectroscopic techniques can validate structures derived from crystallography, and it can be a valuable complementary method before structure-function correlations of metallo-proteins can be made on the basis of high resolution X-ray crystal structures.

  1. X-ray damage to the Mn4Ca complex in single crystals of photosystem II: a case study for metalloprotein crystallography.

    Science.gov (United States)

    Yano, Junko; Kern, Jan; Irrgang, Klaus-Dieter; Latimer, Matthew J; Bergmann, Uwe; Glatzel, Pieter; Pushkar, Yulia; Biesiadka, Jacek; Loll, Bernhard; Sauer, Kenneth; Messinger, Johannes; Zouni, Athina; Yachandra, Vittal K

    2005-08-23

    X-ray absorption spectroscopy was used to measure the damage caused by exposure to x-rays to the Mn(4)Ca active site in single crystals of photosystem II as a function of dose and energy of x-rays, temperature, and time. These studies reveal that the conditions used for structure determination by x-ray crystallography cause serious damage specifically to the metal-site structure. The x-ray absorption spectra show that the structure changes from one that is characteristic of a high-valent Mn(4)(III(2),IV(2)) oxo-bridged Mn(4)Ca cluster to that of Mn(II) in aqueous solution. This damage to the metal site occurs at a dose that is more than one order of magnitude lower than the dose that results in loss of diffractivity and is commonly considered safe for protein crystallography. These results establish quantitative x-ray dose parameters that are applicable to redox-active metalloproteins. This case study shows that a careful evaluation of the structural intactness of the active site(s) by spectroscopic techniques can validate structures derived from crystallography and that it can be a valuable complementary method before structure-function correlations of metalloproteins can be made on the basis of high-resolution x-ray crystal structures.

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2014-06-01

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

  4. Hexavalent chromium removal from aqueous solutions by a novel powder prepared from Colocasia esculenta leaves.

    Science.gov (United States)

    Nakkeeran, E; Saranya, N; Giri Nandagopal, M S; Santhiagu, A; Selvaraju, N

    2016-08-01

    In this study, batch removal of hexavalent chromium from aqueous solutions by powdered Colocasia esculenta leaves was investigated. Batch experiments were conducted to study the effects of adsorption of Cr(VI) at different pH values, initial concentrations, agitation speeds, temperatures, and contact times. The biosorbent was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectrometer analysis. The biosorptive capacity of the adsorbent was dependent on the pH of the chromium solution in which maximum removal was observed at pH 2. The adsorption equilibrium data were evaluated for various adsorption isotherm models, kinetic models, and thermodynamics. The equilibrium data fitted well with Freundlich and Halsey models. The adsorption capacity calculated was 47.62 mg/g at pH 2. The adsorption kinetic data were best described by pseudo-second-order kinetic model. Thus, Colocasia esculenta leaves can be considered as one of the efficient and cheap biosorbents for hexavalent chromium removal from aqueous solutions.

  5. Synthesis and characterization of quaternized bacterial cellulose prepared in homogeneous aqueous solution.

    Science.gov (United States)

    Zhang, Hairong; Guo, Haijun; Wang, Bo; Shi, Silan; Xiong, Lian; Chen, Xinde

    2016-01-20

    In this work, bacterial cellulose (BC) was activated by ethylenediamine (EDA) and then dissolved in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) aqueous solutions. The resulting transparent solution was cast on a glass plate to prepare regenerated BC. Then cationic BC was prepared homogeneously by the reaction between regenerated BC and 3-chloro-2-hydroxypropyl-trimethyl ammonium chloride (CHPTAC) in a NaOH/urea aqueous solution. Structure and properties of the BC and its products were characterized by different techniques such as X-ray diffraction (XRD), Fourier transform spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). The results showed that there was no significant difference between the structures of BC, activated BC and regenerated BC. The effects of different temperature and molar ratio of CHPTAC to anhydroglucose unit (AGU) on the degree of substitution (DS) value were examined. The DS values of cationic BC ranged between 0.21 and 0.51.

  6. Neutron and X-ray Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Carini, Gabriella [SLAC National Accelerator Lab., Menlo Park, CA (United States); Denes, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gruener, Sol [Cornell Univ., Ithaca, NY (United States); Lessner, Elianne [Dept. of Energy (DOE), Washington DC (United States). Office of Science Office of Basic Energy Sciences

    2012-08-01

    (and two computing hurdles that result from the corresponding increase in data volume) for the detector community to overcome in order to realize the full potential of BES neutron and X-ray facilities. Resolving these detector impediments will improve scientific productivity both by enabling new types of experiments, which will expand the scientific breadth at the X-ray and neutron facilities, and by potentially reducing the beam time required for a given experiment. These research priorities are summarized in the table below. Note that multiple, simultaneous detector improvements are often required to take full advantage of brighter sources. High-efficiency hard X-ray sensors: The fraction of incident particles that are actually detected defines detector efficiency. Silicon, the most common direct-detection X-ray sensor material, is (for typical sensor thicknesses) 100% efficient at 8 keV, 25%efficient at 20 keV, and only 3% efficient at 50 keV. Other materials are needed for hard X-rays. Replacement for 3He for neutron detectors: 3He has long been the neutron detection medium of choice because of its high cross section over a wide neutron energy range for the reaction 3He + n —> 3H + 1H + 0.764 MeV. 3He stockpiles are rapidly dwindling, and what is available can be had only at prohibitively high prices. Doped scintillators hold promise as ways to capture neutrons and convert them into light, although work is needed on brighter, more efficient scintillator solutions. Neutron detectors also require advances in speed and resolution. Fast-framing X-ray detectors: Today’s brighter X-ray sources make time-resolved studies possible. For example, hybrid X-ray pixel detectors, initially developed for particle physics, are becoming fairly mature X-ray detectors, with considerable development in Europe. To truly enable time-resolved studies, higher frame rates and dynamic range are required, and smaller pixel sizes are desirable. High-speed spectroscopic X-ray detectors

  7. A physical picture of atomic motions within the Dickerson DNA dodecamer in solution derived from joint ensemble refinement against NMR and large-angle X-ray scattering data.

    Science.gov (United States)

    Schwieters, Charles D; Clore, G Marius

    2007-02-06

    The structure and dynamics of the Dickerson DNA dodecamer [5'd(CGCGAATTCGCG)2] in solution have been investigated by joint simulated annealing refinement against NMR and large-angle X-ray scattering data (extending from 0.25 to 3 A-1). The NMR data comprise an extensive set of hetero- and homonuclear residual dipolar coupling and 31P chemical shift anisotropy restraints in two alignment media, supplemented by NOE and 3J coupling data. The NMR and X-ray scattering data cannot be fully ascribed to a single structure representation, indicating the presence of anisotropic motions that impact the experimental observables in different ways. Refinement with ensemble sizes (Ne) of >or=2 to represent the atomic motions reconciles all the experimental data within measurement error. Cross validation against both the dipolar coupling and X-ray scattering data suggests that the optimal ensemble size required to account for the current data is 4. The resulting ensembles permit one to obtain a detailed view of the conformational space sampled by the dodecamer in solution and permit one to analyze fluctuations in helicoidal parameters, sugar puckers, and BI-BII backbone transitions and to obtain quantitative metrics of atomic motion such as generalized order parameters and thermal B factors. The calculated order parameters are in good agreement with experimental order parameters obtained from 13C relaxation measurements. Although DNA behaves as a relatively rigid rod with a persistence length of approximately 150 bp, dynamic conformational heterogeneity at the base pair level is functionally important since it readily permits optimization of intermolecular protein-DNA interactions.

  8. Phase transfer of platinum nanoparticles from aqueous to organic solutions using fatty amine molecules

    Indian Academy of Sciences (India)

    Ashavani Kumar; Hrushikesh M Joshi; Anandrao B Mandale; Rajendra Srivastava; Suguna D Adyanthaya; Renu Pasricha; Murali Sastry

    2004-08-01

    In this report we demonstrate a simple process based on amine chemistry for the phase transfer of platinum nanoparticles from an aqueous to an organic solution. The phase transfer was accomplished by vigorous shaking of a biphasic mixture of platinum nanoparticles synthesised in an aqueous medium and octadecylamine (ODA) in hexane. During shaking of the biphasic mixture, the aqueous platinum nanoparticles complex via either coordination bond formation or weak covalent interaction with the ODA molecules present in the organic phase. This process renders the nanoparticles sufficiently hydrophobic and dispersible in the organic phase. The ODA-stabilised platinum nanoparticles could be separated out from hexane in the form of a powder that is readily redispersible in weakly polar and nonpolar organic solvents. The ODA-capped platinum nanoparticles show high catalytic activity in hydrogenation reactions and this is demonstrated in the efficient conversion of styrene to ethyl benzene. The nature of binding of the ODA molecules to the platinum nanoparticles surface was characterised by thermogravimetry, transmission electron microscopy (TEM), X-ray photoemission spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR).

  9. Ozone photolysis of paracetamol in aqueous solution.

    Science.gov (United States)

    Neamţu, Mariana; Bobu, Maria; Kettrup, Antonius; Siminiceanu, Ilie

    2013-01-01

    The degradation of a paracetamol (N-acetil-para-aminofenol) aqueous solution (C (0) P = 5 mmol L(-1)) is studied in a bench-scale setup by means of simple ozonation (O3) and ozonation catalyzed with UV light (O3/UV) in order to quantify the influence of UV light on the degradation process. The results have shown that under the adopted experimental conditions (25°C, applied ozone dose = 9.8 mg L(-1) and gas flow rate of 20 L h(-1)) both oxidative systems are capable of removing the substrate with mineralization degrees up to 51% for ozonation and 53% for O3/UV. HPICE chromatography allowed the detection of nitrate ions and maleic and oxalic acids as ultimate carboxylic acids. The experimental data have been interpreted through 5 indicators: the conversion of paracetamol (XP ), the conversion degree of TOC (XTOC ), the apparent rate constant (kap ), the Hatta number (Ha) and the enhancement factor (E). The main advantage of photo-ozonation compared to simple ozonation was a more advanced conversion (79% vs. 92% after 90 min). The paracetamol decay follows a pseudo-first-order reaction with a superior rate constant (higher by 54%) for the UV catalyzed system in comparison with direct ozonation. Mineralization is slightly accelerated (+4%) in the O3/UV system, due to the additional production of hydroxyl radicals induced by the UV light and a higher Hatta number (+24%). Nevertheless, the process was still in the slow reaction kinetic regime (Ha < 0.3), and the enhancement factor was not significantly increased. The results are useful for the design and scale-up of the gas-liquid processes.

  10. Photolysis of Periodate and Periodic Acid in Aqueous Solution

    DEFF Research Database (Denmark)

    Sehested, Knud; Kläning, U. K.

    1978-01-01

    The photochemistry of periodate and periodic acid in aqueous solution was studied (i) by quantum yield measurements at low light intensity (ii) by flash photolysis, and (iii) by photolysis of glassy samples at 77 K. The photochemical studies were supplemented with pulse radiolysis studies...... of aqueous periodate solutions and with kinetic studies using stopped-flow technique. In strongly alkaline solution the photodecomposition of periodate proceeds via formation of O– and IVI. At pH

  11. Thermophysical Properties of Aqueous Solutions Used as Secondary Working Fluids

    OpenAIRE

    Melinder, Åke

    2007-01-01

    Secondary working fluids (secondary refrigerants, heat transfer fluids, antifreezes, brines) have long been used in various indirect re-frigeration and heat pump systems. Aqueous solutions (water solu-tions) have long been used as single phase (liquid only) secondary working fluids for cooling in supermarkets, ice rinks, heat recovery systems, heat pumps and other applications. However, aqueous solutions are increasingly used also for freezers in supermarkets and other applications in low tem...

  12. X-ray Echo Spectroscopy.

    Science.gov (United States)

    Shvyd'ko, Yuri

    2016-02-26

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >10^{8}) with broadband ≃5-13  meV dispersing systems are introduced featuring more than 10^{3} signal enhancement. The technique is general, applicable in different photon frequency domains.

  13. X-ray Echo Spectroscopy

    Science.gov (United States)

    Shvyd'ko, Yuri

    2016-02-01

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >108 ) with broadband ≃5 - 13 meV dispersing systems are introduced featuring more than 103 signal enhancement. The technique is general, applicable in different photon frequency domains.

  14. X-ray echo spectroscopy

    CERN Document Server

    Shvyd'ko, Yuri

    2015-01-01

    X-ray echo spectroscopy, a counterpart of neutron spin-echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a point-like x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x-rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1--0.02-meV ultra-high-resolution IXS applications (resolving power $> 10^8$) with broadband $\\simeq$~5--13~meV dispersing systems are introduced featuring more than $10^3$ signal e...

  15. Preparation and characterization of zirconia-loaded lignocellulosic butanol residue as a biosorbent for phosphate removal from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Zong, Enmin [Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou 318000 (China); Liu, Xiaohuan, E-mail: liuxiaohuancaf@163.com [School of Engineering, National Engineering and Technology Research Center of Wood-Based Resources Comprehensive Utilization, and Key Laboratory of Wood Science and Technology of Zhejiang Province, Zhejiang Agriculture and Forestry University, Hangzhou, Lin’an 311300 (China); Jiang, Jinhua [Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou 318000 (China); Fu, Shenyuan [School of Engineering, National Engineering and Technology Research Center of Wood-Based Resources Comprehensive Utilization, and Key Laboratory of Wood Science and Technology of Zhejiang Province, Zhejiang Agriculture and Forestry University, Hangzhou, Lin’an 311300 (China); Chu, Fuxiang [Institute of Chemical Industry of Forestry Products, CAF, Nanjing 210037 (China)

    2016-11-30

    Highlights: • LBR-Zr was evaluated as a novel biosorbent for phosphate removal. • Effects of process factors on phosphate adsorption were studied in detail. • LBR-Zr showed markedly enhanced phosphate adsorption compared to LBR. • The underlying mechanism for phosphate adsorption of LBR-Zr was fully investigated. - Abstract: Zirconium(IV) loaded lignocellulosic butanol residue (LBR-Zr) used for the adsorption of phosphate (P) ions from aqueous solution was synthesized and evaluated. The adsorption isotherms were fitted well with the Freundlich and Temkin modes. Thermodynamic analyses indicated that phosphate adsorption on the LBR-Zr increased with increasing temperature from 298 to 338 K. The kinetic datas were described better by the pseudo-second-order adsorption kinetic rate model. Increasing pH suppressed phosphate adsorption. Coexisting anions study exhibited that the incorporation of CO{sub 3}{sup 2−} anion had the largest influence on the phosphate adsorption capacity. The mechanism of adsorption process on LBR-Zr was analyzed by FTIR (Fourier transform infrared spectroscopy), scanning electron microscope (SEM) with an EDX (energy dispersive X-ray) and X-ray photoelectron spectroscopy (XPS) technologies, respectively. The above results confirmed that surface hydroxyl groups on biosorbent LBR-Zr were replaced by phosphate. The LBR-Zr with good specific affinity towards phosphate was a promising biosorbent for phosphate removal from aqueous solution. The research would be beneficial for developing a promising, eco-friendly phosphate biosorbent from plentiful lignocellulosic butanol residue.

  16. Preparation and characterization of zirconia-loaded lignocellulosic butanol residue as a biosorbent for phosphate removal from aqueous solution

    Science.gov (United States)

    Zong, Enmin; Liu, Xiaohuan; Jiang, Jinhua; Fu, Shenyuan; Chu, Fuxiang

    2016-11-01

    Zirconium(IV) loaded lignocellulosic butanol residue (LBR-Zr) used for the adsorption of phosphate (P) ions from aqueous solution was synthesized and evaluated. The adsorption isotherms were fitted well with the Freundlich and Temkin modes. Thermodynamic analyses indicated that phosphate adsorption on the LBR-Zr increased with increasing temperature from 298 to 338 K. The kinetic datas were described better by the pseudo-second-order adsorption kinetic rate model. Increasing pH suppressed phosphate adsorption. Coexisting anions study exhibited that the incorporation of CO32- anion had the largest influence on the phosphate adsorption capacity. The mechanism of adsorption process on LBR-Zr was analyzed by FTIR (Fourier transform infrared spectroscopy), scanning electron microscope (SEM) with an EDX (energy dispersive X-ray) and X-ray photoelectron spectroscopy (XPS) technologies, respectively. The above results confirmed that surface hydroxyl groups on biosorbent LBR-Zr were replaced by phosphate. The LBR-Zr with good specific affinity towards phosphate was a promising biosorbent for phosphate removal from aqueous solution. The research would be beneficial for developing a promising, eco-friendly phosphate biosorbent from plentiful lignocellulosic butanol residue.

  17. Critical properties of aqueous solutions. Part 1: Experimental data

    Science.gov (United States)

    Abdulagatov, A. I.; Stepanov, G. V.; Abdulagatov, I. M.

    2008-08-01

    All data available in the literature on the critical properties of binary aqueous solutions like H2O + common salt, H2O + hydrocarbon, H2O + alcohol, H2O + gas, and others are gathered. Methods for determining them are presented together with errors and concentration measurement intervals for each source of data. The format in which the data are presented will allow the readers to quickly find the necessary information on the critical properties of aqueous solutions from the original sources and use them for solving scientific and engineering tasks. Certain general features of the critical lines and phase diagrams of aqueous solutions with volatile and nonvolatile components are discussed.

  18. Degradation of Hydrogenated Nitrile-butadiene Rubber in Aqueous Solutions of H2S or HCl

    Institute of Scientific and Technical Information of China (English)

    CONG Chuan-bo; CUI Can-can; MENG Xiao-yu; LU Shao-jie; ZHOU Qiong

    2013-01-01

    The degradation of hydrogenated nitrile-butadiene rubber(HNBR) soaped in aqueous solutions of H2S and HCl was investigated.The samples unexposed and exposed to different solutions were characterized by 13C nuclear magnetic resonance(13C NMR),X-ray photoelectron and infrared spectroscopies.In contrast to those of unexposed samples and samples soaped in HCl solution,the mechanical properties of samples exposed to H2S solution significantly deteriorated,in which the new groups of C(=O)-NH2,C-S-C and C=S emerged.The mechanism of C=S and C-S-C formation was speculated,except for that of the formation of group C(=O)-NH2,which was widely discussed in acidic condition such as HC1 solution.The formation of C-S-C was due to radical reaction initiated by mercapto radical and that of C=S was due to nucleophilic reaction initiated by mercapto cations.This finding is helpful to understanding the seal failure of HNBR in working environment containing H2S.

  19. Removal of Zinc from Aqueous Solutions by Magnetite Silica Core-Shell Nanoparticles

    Directory of Open Access Journals (Sweden)

    Masoomeh Emadi

    2013-01-01

    Full Text Available Magnetite silica core-shell nanoparticles (Fe3O4-SiO2 were synthesized and evaluated as a nanoadsorbent for removing Zn(II from aqueous solutions. The core-shell nanoparticles were prepared by combining coprecipitation and sol-gel methods. Nanoparticles were characterized by X-ray diffraction, transmission electron microscopy (TEM, and FT-IR. The magnetization values of nanoparticles were measured with vibrating sample magnetometer (VSM. The adsorption of Zn(II ions was examined by batch equilibrium technique. The effects of pH, initial Zn(II concentration, and contact time on the efficiency of Zn(II removal were studied. The equilibrium data, analyzed by using Langmuir and Freundlich isotherm models, showed better agreement with the former model. Using the Langmuir isotherm model, maximum capacity of the nanoadsorbent for Zn(II was found to be 119 mg g−1 at room temperature. Kinetic studies were conducted and the resulting data were analyzed using first- and second-order equations; pseudo-second-order kinetic equation was found to provide the best correlation. The adsorption and sedimentation times were very low. The nanoadsorbent can be easily separated from aqueous solution by a magnet. Repeated adsorption acid regeneration cycles were performed to examine the stability and reusability of the nanoadsorbent. The result of this study proved high stability and reusability of Fe3O4-SiO2 as an adsorbent for Zn(II ions.

  20. Removal of Pb(II) from aqueous solution by oxidized multiwalled carbon nanotubes.

    Science.gov (United States)

    Xu, Di; Tan, Xiaoli; Chen, Changlun; Wang, Xiangke

    2008-06-15

    Oxidized multiwalled carbon nanotubes (MWCNTs) were employed as sorbent to study the sorption characteristic of Pb(II) from aqueous solution as a function of contact time, pH, ionic strength, foreign ions, and oxidized MWCNTs' contents under ambient conditions using batch technique. The results indicate that sorption of Pb(II) on oxidized MWCNTs is strongly dependent on pH values, and independent of ionic strength and the type of foreign ions. The removal of Pb(II) to oxidized MWCNTs is rather quickly and the kinetic sorption can be described by a pseudo-second-order model very well. Sorption of Pb(II) is mainly dominated by surface complexation rather than ion exchange. The efficient removal of Pb(II) from aqueous solution is limited at pH 7-10. X-ray photoelectron spectroscopy (XPS) is performed to study the sorption mechanism at a molecular level and thereby to identify the species of the sorption processes. The 3-D relationship of pH, Ceq and q indicates that all the data of Ceq-q lie in a straight line with slope -V/m and intercept C0V/m for the same initial concentration of Pb(II) and same content of oxidized MWCNTs of each experimental data.

  1. XANES Reveals the Flexible Nature of Hydrated Strontium in Aqueous Solution.

    Science.gov (United States)

    D'Angelo, Paola; Migliorati, Valentina; Sessa, Francesco; Mancini, Giordano; Persson, Ingmar

    2016-05-05

    X-ray absorption near-edge structure (XANES) spectroscopy has been used to determine the structure of the hydrated strontium in aqueous solution. The XANES analysis has been carried out using solid [Sr(H2O)8](OH)2 as reference model. Classical and Car-Parrinello molecular dynamics (MD) simulations have been carried out and in the former case two different sets of Lennard-Jones parameters have been used for the Sr(2+) ion. The best performing theoretical approach has been chosen on the basis of the experimental results. XANES spectra have been calculated starting from MD trajectories, without carrying out any minimization of the structural parameters. This procedure allowed us to properly account for thermal and structural fluctuations occurring in the aqueous solution in the analysis of the experimental spectrum. A deconvolution procedure has been applied to the raw absorption data thus increasing the sensitivity of XANES spectroscopy. One of the classical MD simulations has been found to provide a XANES theoretical spectrum in better agreement with the experimental data. An 8-fold hydration complex with a Sr-O distance of 2.60 Å has been found to be compatible with the XANES data, in agreement with previous findings. However, the hydration shells of the strontium ions have been found to have a flexible nature with a fast ligand exchange rate between the first and second hydration shell occurring in the picosecond time scale.

  2. Transformation of modified brushite to hydroxyapatite in aqueous solution: effects of potassium substitution.

    Science.gov (United States)

    Kumar, M; Xie, J; Chittur, K; Riley, C

    1999-08-01

    Brushite (dicalcium phosphate dihydrate, DCPD, CaHPO4 x 2H2O) was deposited electrolytically from calcium dihydrogen phosphate solution with and without potassium chloride (KCl) as a supporting electrolyte. The kinetics of brushite transformation to hydroxyapatite (HA, Ca5(PO4)3OH) in the presence of calcium and protein free, aqueous body fluid (Hank's balanced salt solution, HBSS) was investigated. We present evidence that the deposition of brushite in a KCl-supported electrochemical bath yields a modified brushite where some of the calcium is substituted by potassium. Transformation of both normal (i.e. potassium free) and modified brushite to hydroxyapatite upon exposure to calcium and protein-free aqueous fluid (HBSS) was followed by reflectance Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques. Changes in the morphology of the coatings were studied using scanning electron microscopy (SEM). Results indicate that modified brushite undergoes faster transformation to hydroxyapatite in HBSS in comparison to normal brushite. Our results show that the presence of potassium ions in the brushite not only favors the formation of different intermediate phases but also alters transformation rates to HA.

  3. Alkaline deoxygenated graphene oxide as adsorbent for cadmium ions removal from aqueous solutions.

    Science.gov (United States)

    Liu, Jun; Du, Hongyan; Yuan, Shaowei; He, Wanxia; Yan, Pengju; Liu, Zhanhong

    2015-01-01

    Alkaline deoxygenated graphene oxide (aGO) was prepared through alkaline hydrothermal treatment and used as adsorbent to remove Cd(II) ions from aqueous solutions for the first time. The characterization results of transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and Fourier transform infrared (FT-IR) spectra indicate that aGO was successfully synthesized. The batch adsorption experiments showed that the adsorption kinetics could be described by the pseudo-second-order kinetic model, and the isotherms equilibrium data were well fitted with the Langmuir model. The maximum adsorption capacity of Cd(II) on aGO was 156 mg/g at pH 5 and T=293 K. The adsorption thermodynamic parameters indicated that the adsorption process was a spontaneous and endothermic reaction. The mainly adsorption mechanism speculated from FT-IR results may be attributed to the electrostatic attraction between Cd2+ and negatively charged groups (-CO-) of aGO and cation-π interaction between Cd2+ and the graphene planes. The findings of this study demonstrate the potential utility of the nanomaterial aGO as an effective adsorbent for Cd(II) removal from aqueous solutions.

  4. Hydrothermal synthesis of silico-manganese nanohybrid for Cu(II) adsorption from aqueous solution

    Science.gov (United States)

    Zhu, Qiufeng; Wang, Liting; An, Zehuan; Ye, Hong; Feng, Xudong

    2016-05-01

    A novel silico-manganese nanohybrid adsorbent (SMNA) was synthesized by a facile hydrothermal method, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR) and zeta potential measurement. The adsorption of Cu(II) ions from aqueous solution on the SMNA was investigated with variations in contact time, pH and initial Cu(II) concentration. The results showed that hydrothermal method would generate nanowire/nanorod incomplete crystallite (δ-MnO2) adsorbent. The adsorption of Cu(II) onto SMNA increased sharply within 25 min and reached equilibrium gradually. The maximum adsorption capacities of SMNA for Cu(II) were ∼40-88 mg g-1, which was lower than δ-MnO2 (92.42 mg g-1) but had a lower pH dependency. As compared with δ-MnO2, higher adsorption capacities of SMNA (7.5-15 wt% of silica doping amount) for Cu(II) could be observed when pH of the aqueous solution was low (removal of Cu(II) by the as-prepared adsorbents was dominated by migration of Cu(II). The possibility of Cu(II) recovery was also investigated and it revealed that SMNA was a promising recyclable adsorbent for removal of heavy metal ions in water and wastewater treatment.

  5. Ozone oxidation of cassava starch in aqueous solution at different pH.

    Science.gov (United States)

    Klein, Bruna; Vanier, Nathan Levien; Moomand, Khalid; Pinto, Vânia Zanella; Colussi, Rosana; da Rosa Zavareze, Elessandra; Dias, Alvaro Renato Guerra

    2014-07-15

    Ozone is a more powerful oxidant than common oxidising agents, such as sodium hypochlorite and hydrogen peroxide. It is considered as a safer starch modification method for both consumers and the environment. However, few studies have investigated the changes in starch properties associated with ozone treatment, particularly when applied in aqueous solution. This work aimed to evaluate the carbonyl and carboxyl contents, the X-ray diffraction patterns, the spectrum profiles of Fourier transform infrared spectroscopy, the pasting properties and the surface morphology of ozone-oxidised cassava starch during 60 min under different pH (3.5, 6.5 and 9.5) at 25°C. The pH 6.5 and 9.5 seemed to favour the cross-linking between the depolymerised starch molecules during ozonation. The pH 3.5 was more effective in reducing the peak viscosity, breakdown, setback and final viscosity of cassava starch during ozonation in aqueous solution. No differences in the granule surface morphology were observed in the ozone-treated cassava starches compared to native starch.

  6. Corrosion behaviour of galvanized steel and electroplating steel in aqueous solution: AC impedance study and XPS

    Energy Technology Data Exchange (ETDEWEB)

    Lebrini, M.; Fontaine, G. [Laboratoire des Procedes d' Elaboration des Revetements Fonctionnels, LSPES UMR CNRS 8008, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Gengembre, L. [Unite de Catalyse et Chimie du solide UMR 8181 Bat C3, USTL, F-59655 Villeneuve d' Ascq Cedex (France); Traisnel, M. [Laboratoire des Procedes d' Elaboration des Revetements Fonctionnels, LSPES UMR CNRS 8008, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France)], E-mail: Michel.Traisnel@ensc-lille.fr; Lerasle, O.; Genet, N. [TOTAL France, Centre de Recherche de Solaize, Chemin du canal, BP 22, F-69360 Solaize (France)

    2008-08-30

    The efficiency of a new triazole derivative, namely, 2-{l_brace}(2-hydroxyethyl)[(4-methyl-1H-1,2,3-benzotriazol-1-yl)methyl]amino{r_brace} ethanol (TTA) has been studied for corrosion inhibition of galvanized steel and electroplating steel in aqueous solution. Corrosion inhibition was studied using electrochemical impedance spectroscopy (EIS). These studies have shown that TTA was a very good inhibitor. Data obtained from EIS show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. The corrosion behaviour of galvanized steel and electroplating steel in aqueous solution was also investigated in the presence of 4-methyl-1H-benzotriazole (TTA unsubstituted) by EIS. These studies have shown that the ability of the molecule to adsorb on the steel surface was dependent on the group in triazole ring substituent. X-ray photoelectron spectroscopy surface analysis with TTA shows that it chemisorbed on surface of galvanized steel and electroplating steel.

  7. Removal of boron from aqueous solution by clays and modified clays.

    Science.gov (United States)

    Karahan, Senem; Yurdakoç, Mürüvvet; Seki, Yoldaş; Yurdakoç, Kadir

    2006-01-01

    In order to increase the adsorption capacities of bentonite, sepiolite, and illite for the removal of boron form aqueous solution, the clay samples were modified by nonylammonium chloride. Specific surface areas of the samples were determined as a result of N2 adsorption-desorption at 77 K using the BET method. X-ray powder diffraction analysis of the clays and modified clays was used to determine the effects of modifying agents on the layer structure of the clays. The surface characterization of clays and modified clay samples was conducted using the FTIR technique before and after the boron adsorption. For the optimization of the adsorption of boron on clays and modified clays, the effect of pH and ionic strength was examined. The results indicate that adsorption of boron can be achieved by regulating pH values in the range of 8-10 and high ionic strength. In order to find the adsorption characteristics, Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherms were applied to the adsorption data. The data were well described by Freundlich and Dubinin-Radushkevich adsorption isotherms while the fit of Langmuir equation to adsorption data was poor. It was reached that modification of bentonite and illite with nonylammonium chloride increased the adsorption capacity for boron sorption from aqueous solution.

  8. Electrodeposition of Sm–Co film with high Sm content from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Long, Xiong-fei; Guo, Guang-hua, E-mail: guogh@mail.csu.edu.cn; Li, Xin-hua; Xia, Qing-lin; Zhang, Jin-fang

    2013-12-02

    Sm–Co films with high Sm content were electrodeposited by potentiostat technique from the aqueous solution containing glycine as a complexing agent. The Cyclic Voltammetry measurements showed that the glycine plays a crucial role in the electrodeposition of Sm–Co films. The forming of stable complex [Co{sup II}Sm{sup III}(Gly{sup −}){sub 2}(HGly{sup ±})]{sup 3+} facilitated the codeposition of Sm with Co at relatively low potential, which made it possible to fabricate the Sm–Co films with high Sm content. The Sm–Co film with 43 at.% Sm had been obtained. X-ray diffraction showed that the as-deposited Sm–Co films were amorphous. After annealing at 600 °C for 2 h in Ar atmosphere, the films became crystalline and the permanent Sm{sub 2}Co{sub 17} phase was formed, which significantly enhanced the coercivity of the films. - Highlights: • The Sm–Co film with high Sm content is electrodeposited from aqueous solutions. • The addition of glycine facilitates the codeposition of Sm with Co at relatively low potential. • The Sm{sub 2}Co{sub 17} phase is formed in the annealed Sm–Co film.

  9. Adsorption of Pb(2+) from aqueous solution using spinel ferrite prepared from steel pickling sludge.

    Science.gov (United States)

    Fang, Binbin; Yan, Yubo; Yang, Yang; Wang, Fenglian; Chu, Zhen; Sun, Xiuyun; Li, Jiansheng; Wang, Lianjun

    2016-01-01

    In this paper, spinel ferrite with high crystallinity and high saturation magnetization was successfully prepared from steel pickling sludge by adding iron source and precipitator in the hydrothermal condition. The obtained spinel ferrite was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM), and Zeta potential methods and investigated as an adsorbent for removal of Pb(2+) from aqueous solution. Batch experiments were performed by varying the pH values, contact time, temperature and initial metal concentration. The result of pH impact showed that the adsorption of Pb(2+) was a pH dependent process, and the pH 5.8 ± 0.2 was found to be the optimum condition. The achieved experimental data were analyzed with various kinetic and isotherm models. The kinetic studies revealed that Pb(2+) adsorption onto spinel ferrite followed a pseudo-second order model, and the Langmuir isotherm model provided the perfect fit to the equilibrium experimental data. At different temperatures, the maximum Pb(2+) adsorption capacities calculated from the Langmuir equation were in the range of 126.5-175.4 mg/g, which can be in competition with other adsorbents. The thermodynamic results showed that the spinel ferrite could spontaneously and endothermically adsorb Pb(2+) from aqueous solution. The regeneration studies showed that spinel ferrite could be used five times (removal efficiency (%) >90%) by desorption with HNO3 reagent.

  10. X-ray imaging: Perovskites target X-ray detection

    Science.gov (United States)

    Heiss, Wolfgang; Brabec, Christoph

    2016-05-01

    Single crystals of perovskites are currently of interest to help fathom fundamental physical parameters limiting the performance of perovskite-based polycrystalline solar cells. Now, such perovskites offer a technology platform for optoelectronic devices, such as cheap and sensitive X-ray detectors.

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

    Science.gov (United States)

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

    2010-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-10-01

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

  13. Neutron and X-ray Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Carini, Gabriella [SLAC National Accelerator Lab., Menlo Park, CA (United States); Denes, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gruener, Sol [Cornell Univ., Ithaca, NY (United States); Lessner, Elianne [Dept. of Energy (DOE), Washington DC (United States). Office of Science Office of Basic Energy Sciences

    2012-08-01

    (and two computing hurdles that result from the corresponding increase in data volume) for the detector community to overcome in order to realize the full potential of BES neutron and X-ray facilities. Resolving these detector impediments will improve scientific productivity both by enabling new types of experiments, which will expand the scientific breadth at the X-ray and neutron facilities, and by potentially reducing the beam time required for a given experiment. These research priorities are summarized in the table below. Note that multiple, simultaneous detector improvements are often required to take full advantage of brighter sources. High-efficiency hard X-ray sensors: The fraction of incident particles that are actually detected defines detector efficiency. Silicon, the most common direct-detection X-ray sensor material, is (for typical sensor thicknesses) 100% efficient at 8 keV, 25%efficient at 20 keV, and only 3% efficient at 50 keV. Other materials are needed for hard X-rays. Replacement for 3He for neutron detectors: 3He has long been the neutron detection medium of choice because of its high cross section over a wide neutron energy range for the reaction 3He + n —> 3H + 1H + 0.764 MeV. 3He stockpiles are rapidly dwindling, and what is available can be had only at prohibitively high prices. Doped scintillators hold promise as ways to capture neutrons and convert them into light, although work is needed on brighter, more efficient scintillator solutions. Neutron detectors also require advances in speed and resolution. Fast-framing X-ray detectors: Today’s brighter X-ray sources make time-resolved studies possible. For example, hybrid X-ray pixel detectors, initially developed for particle physics, are becoming fairly mature X-ray detectors, with considerable development in Europe. To truly enable time-resolved studies, higher frame rates and dynamic range are required, and smaller pixel sizes are desirable. High-speed spectroscopic X-ray detectors

  14. Solution structures of 2 : 1 and 1 : 1 DNA polymerase-DNA complexes probed by ultracentrifugation and small-angle X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Kuo-Hsiang; Niebuhr, Marc; Aulabaugh, Ann; Tsai, Ming-Daw [OSU; (Wyeth); (SSRL)

    2008-03-25

    We report small-angle X-ray scattering (SAXS) and sedimentation velocity (SV) studies on the enzyme-DNA complexes of rat DNA polymerase β (Pol β) and African swine fever virus DNA polymerase X (ASFV Pol X) with one-nucleotide gapped DNA. The results indicated formation of a 2 : 1 Pol β-DNA complex, whereas only 1 : 1 Pol X-DNA complex was observed. Three-dimensional structural models for the 2 : 1 Pol β-DNA and 1 : 1 Pol X-DNA complexes were generated from the SAXS experimental data to correlate with the functions of the DNA polymerases. The former indicates interactions of the 8 kDa 5'-dRP lyase domain of the second Pol β molecule with the active site of the 1 : 1 Pol β-DNA complex, while the latter demonstrates how ASFV Pol X binds DNA in the absence of DNA-binding motif(s). As ASFV Pol X has no 5'-dRP lyase domain, it is reasonable not to form a 2 : 1 complex. Based on the enhanced activities of the 2 : 1 complex and the observation that the 8 kDa domain is not in an optimal configuration for the 5'-dRP lyase reaction in the crystal structures of the closed ternary enzyme-DNA-dNTP complexes, we propose that the asymmetric 2 : 1 Pol β-DNA complex enhances the function of Pol β.

  15. Solution Structures of 2 : 1 And 1 : 1 DNA Polymerase - DNA Complexes Probed By Ultracentrifugation And Small-Angle X-Ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Tang, K.H.; /Ohio State U.; Niebuhr, M.; /SLAC, SSRL; Aulabaugh, A.; /Wyeth Res. Biophys., Pearl River; Tsai, M.D.; /Ohio State U. /SLAC, SSRL

    2009-04-30

    We report small-angle X-ray scattering (SAXS) and sedimentation velocity (SV) studies on the enzyme-DNA complexes of rat DNA polymerase {beta} (Pol {beta}) and African swine fever virus DNA polymerase X (ASFV Pol X) with one-nucleotide gapped DNA. The results indicated formation of a 2 : 1 Pol {beta}-DNA complex, whereas only 1 : 1 Pol X-DNA complex was observed. Three-dimensional structural models for the 2 : 1 Pol {beta}-DNA and 1 : 1 Pol X-DNA complexes were generated from the SAXS experimental data to correlate with the functions of the DNA polymerases. The former indicates interactions of the 8 kDa 5{prime}-dRP lyase domain of the second Pol {beta} molecule with the active site of the 1 : 1 Pol {beta}-DNA complex, while the latter demonstrates how ASFV Pol X binds DNA in the absence of DNA-binding motif(s). As ASFV Pol X has no 5{prime}-dRP lyase domain, it is reasonable not to form a 2 : 1 complex. Based on the enhanced activities of the 2 : 1 complex and the observation that the 8 kDa domain is not in an optimal configuration for the 5{prime}-dRP lyase reaction in the crystal structures of the closed ternary enzyme-DNA-dNTP complexes, we propose that the asymmetric 2 : 1 Pol {beta}-DNA complex enhances the function of Pol {beta}.

  16. SOMO (SOlution MOdeler) differences between X-Ray- and NMR-derived bead models suggest a role for side chain flexibility in protein hydrodynamics.

    Science.gov (United States)

    Rai, Nithin; Nöllmann, Marcelo; Spotorno, Bruno; Tassara, Giovanni; Byron, Olwyn; Rocco, Mattia

    2005-05-01

    Reduced numbers of frictional/scattering centers are essential for tractable hydrodynamic and small-angle scattering data modeling. We present a method for generating medium-resolution models from the atomic coordinates of proteins, basically by using two nonoverlapping spheres of differing radii per residue. The computed rigid-body hydrodynamic parameters of BPTI, RNase A, and lysozyme models were compared with a large database of critically assessed experimental values. Overall, very good results were obtained, but significant discrepancies between X-ray- and NMR-derived models were found. Interestingly, they could be accounted for by properly considering the extent to which highly mobile surface side chains differently affect translational/rotational properties. Models of larger structures, such as fibrinogen fragment D and citrate synthase, also produced consistent results. Foremost among this method's potential applications is the overall conformation and dynamics of modular/multidomain proteins and of supramolecular complexes. The possibility of merging data from high- and low-resolution structures greatly expands its scope.

  17. The Million Optical - Radio/X-ray Associations (MORX) Catalogue

    CERN Document Server

    Flesch, Eric W

    2016-01-01

    This automated catalogue combines all the largest published optical, radio and X-ray sky catalogues to find probable radio/X-ray associations to optical objects, plus double radio lobes, using uniform processing against all input data. The total count is 1002855 optical objects so presented. Each object is displayed with J2000 astrometry, optical and radio/X-ray identifiers, red and blue photometry, and calculated probabilities and optical field solutions of the associations. This is the third and final edition of this method.

  18. X-ray Scintillation in Lead Halide Perovskite Crystals

    OpenAIRE

    Birowosuto, M. D.; Cortecchia, D.; Drozdowski, W.; K. Brylew; Łachmański, W.; A. Bruno; Soci, C.

    2016-01-01

    Current technologies for X-ray detection rely on scintillation from expensive inorganic crystals grown at high-temperature, which so far has hindered the development of large-area scintillator arrays. Thanks to the presence of heavy atoms, solution-grown hybrid lead halide perovskite single crystals exhibit short X-ray absorption length and excellent detection efficiency. Here we compare X-ray scintillator characteristics of three-dimensional (3D) MAPbI3 and MAPbBr3 and two-dimensional (2D) (...

  19. Removal of Pb(II) and Cd(II) ions from aqueous solution by thiosemicarbazide modified chitosan.

    Science.gov (United States)

    Li, Manlin; Zhang, Zengqiang; Li, Ronghua; Wang, Jim J; Ali, Amjad

    2016-05-01

    The removal of Pb(II) and Cd(II) ions from aqueous solution by thiosemicarbazide modified chitosan (TCS) was studied in this article. The synthesized TCS was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), element analysis, N2 adsorption-desorption, scanning electron microscopy (SEM) and X-ray photoelectron spectrophotometer (XPS). Moreover, the influence of solution pH, contact time, initial heavy metal concentration, and solution temperature on the adsorption process was examined, and the adsorbent reusability and adsorption mechanisms were also studied. The results showed that TCS adsorbed greater amount of Pb(II) and Cd(II) ions than the raw chitosan. The adsorption amounts of Pb(II) and Cd(II) ions were affected by increasing solution pH and temperature. The maximum adsorption capacities of the TCS for Pb(II) and Cd(II) ions were found to be 325.2 and 257.2 mg/g, respectively. The endothermic adsorption fitted the pseudo-second-order kinetics equation and the adsorption isotherms could be well described by Langmuir model. The metal ions adsorption mechanism was concluded to be mainly dominated by complexation reaction process. The desorption study indicated that the target adsorbent was easy to be regenerated.

  20. Instability of aqueous solutions of polyacrylamide in a hydrodynamic field

    Science.gov (United States)

    Makogon, B. P.; Bykova, E. N.; Bezrukova, M. A.; Klenin, S. I.; Ivanyuta, Yu. F.; Povkh, I. L.; Toryanik, A. I.

    1985-09-01

    This article discusses findings obtained regarding the effect of a hydrodynamic field on the reduced viscosity, effect of turbulent friction reduction, light scattering, double refraction, and optical density of aqueous solutions of hydrolyzed polyacrylamide.

  1. Biosorption of copper (II) ions from synthetic aqueous solutions by drying bed activated sludge

    Energy Technology Data Exchange (ETDEWEB)

    Benaissa, H., E-mail: ho_benaissa@yahoo.fr [Laboratory of Sorbent Materials and Water Treatment, Department of Chemistry, Faculty of Sciences, University of Tlemcen, P.O. Box 119, 13000 Tlemcen (Algeria); Elouchdi, M.A. [Laboratory of Sorbent Materials and Water Treatment, Department of Chemistry, Faculty of Sciences, University of Tlemcen, P.O. Box 119, 13000 Tlemcen (Algeria)

    2011-10-30

    Highlights: {yields} Dried activated sludge has been investigated for the removal of copper ions from aqueous synthetic solutions, in batch conditions. {yields} Copper uptake was time contact, initial copper concentration, initial pH solution and copper salt type dependent. {yields} Maximum copper uptake obtained was q{sub m} = 62.50 mg/g (0.556 mmol/g) under the investigated experimental conditions. - Abstract: In the present work, the usefulness of dried activated sludge has been investigated for the removal of copper ions from synthetic aqueous solutions. Kinetic data and equilibrium sorption isotherm were measured in batch conditions. The influence of some parameters such as: contact time, initial copper concentration, initial pH of solution and copper salt nature on copper biosorption kinetics has been studied. Copper uptake was time contact, initial copper concentration, initial pH solution and copper salt type dependent. Maximum copper sorption was found to occur at initial pH 5. Two simplified kinetic models including a first-order rate equation and a pseudo second-order rate equation were selected to describe the biosorption kinetics. The process followed a pseudo second-order rate kinetics. The process mechanism was found to be complex, consisting of external mass transfer and intraparticle mass transfer diffusion. Copper biosorption process was particle-diffusion-controlled, with some predominance of some external mass transfer at the initial stages for the different experimental parameters studied. Langmuir and Freundlich models were used to describe sorption equilibrium data at natural pH of solution. Results indicated that the Langmuir model gave a better fit to the experimental data than the Freundlich model. Maximum copper uptake obtained was q{sub m} = 62.50 mg/g (0.556 mmol/g) under the investigated experimental conditions. Scanning electron microscopy coupled with X-ray energy dispersed analysis for copper-equilibrated dried activated sludge

  2. Efficiency of aluminum-pillared montmorillonite on the removal of cesium and copper from aqueous solutions.

    Science.gov (United States)

    Karamanis, D; Assimakopoulos, P A

    2007-05-01

    Aluminum-pillared-layered montmorillonites (PILMs) were tested for their potential application in the removal of copper or cesium from aqueous solutions. By varying the initial conditions, several PILMs were prepared and characterized by means of X-ray fluorescence (XRF), proton induced gamma-ray emission (PIGE), X-ray diffraction (XRD) and sorption isotherms. Uptake of metals was studied by means of XRF spectrometry for copper sorption or gamma-ray spectrometry for cesium, using 137Cs as radiotracer. The sorption kinetics and capacity of PILMs were determined in relation to the effects of factors such as the initial metal concentration, initial pH of the solution and the presence of competitive cations. Kinetic studies showed that an equilibrium time of few minutes was needed for the adsorption of metal ions on PILMs. A pseudo-first-order equation was used to describe the sorption process for either copper or cesium. The most effective pH range for the removal of copper and cesium was found to be 4.0-6.0 and 3.0-8.0, respectively. Cesium sorption isotherms were best represented by a two-site Langmuir model while copper isotherms followed the Freundlich or the two-site Langmuir model. Cesium sorption experiments with inorganic or organic competitive cations as blocking agents revealed that the high selective sites of PILMs for cesium sorption (1-2% of total) are surface and edge sites in addition to interlayer exchange sites. In copper sorption, the two sites were determined as interlayer sites of PILMs after restoring their cation exchange capacity and sites associated with the pillar oxides.

  3. Stellar X-Ray Polarimetry

    Science.gov (United States)

    Swank, J.

    2011-01-01

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

  4. X-Ray Diffractive Optics

    Science.gov (United States)

    Dennis, Brian; Li, Mary; Skinner, Gerald

    2013-01-01

    X-ray optics were fabricated with the capability of imaging solar x-ray sources with better than 0.1 arcsecond angular resolution, over an order of magnitude finer than is currently possible. Such images would provide a new window into the little-understood energy release and particle acceleration regions in solar flares. They constitute one of the most promising ways to probe these regions in the solar atmosphere with the sensitivity and angular resolution needed to better understand the physical processes involved. A circular slit structure with widths as fine as 0.85 micron etched in a silicon wafer 8 microns thick forms a phase zone plate version of a Fresnel lens capable of focusing approx. =.6 keV x-rays. The focal length of the 3-cm diameter lenses is 100 microns, and the angular resolution capability is better than 0.1 arcsecond. Such phase zone plates were fabricated in Goddard fs Detector Development Lab. (DDL) and tested at the Goddard 600-microns x-ray test facility. The test data verified that the desired angular resolution and throughput efficiency were achieved.

  5. X-rays and magnetism.

    Science.gov (United States)

    Fischer, Peter; Ohldag, Hendrik

    2015-09-01

    Magnetism is among the most active and attractive areas in modern solid state physics because of intriguing phenomena interesting to fundamental research and a manifold of technological applications. State-of-the-art synthesis of advanced magnetic materials, e.g. in hybrid structures paves the way to new functionalities. To characterize modern magnetic materials and the associated magnetic phenomena, polarized x-rays have emerged as unique probes due to their specific interaction with magnetic materials. A large variety of spectroscopic and microscopic techniques have been developed to quantify in an element, valence and site-sensitive way properties of ferro-, ferri-, and antiferromagnetic systems, such as spin and orbital moments, and to image nanoscale spin textures and their dynamics with sub-ns time and almost 10 nm spatial resolution. The enormous intensity of x-rays and their degree of coherence at next generation x-ray facilities will open the fsec time window to magnetic studies addressing fundamental time scales in magnetism with nanometer spatial resolution. This review will give an introduction into contemporary topics of nanoscale magnetic materials and provide an overview of analytical spectroscopy and microscopy tools based on x-ray dichroism effects. Selected examples of current research will demonstrate the potential and future directions of these techniques.

  6. X-ray backscatter imaging

    Science.gov (United States)

    Dinca, Dan-Cristian; Schubert, Jeffrey R.; Callerame, J.

    2008-04-01

    In contrast to transmission X-ray imaging systems where inspected objects must pass between source and detector, Compton backscatter imaging allows both the illuminating source as well as the X-ray detector to be on the same side of the target object, enabling the inspection to occur rapidly and in a wide variety of space-constrained situations. A Compton backscatter image is similar to a photograph of the contents of a closed container, taken through the container walls, and highlights low atomic number materials such as explosives, drugs, and alcohol, which appear as especially bright objects by virtue of their scattering characteristics. Techniques for producing X-ray images based on Compton scattering will be discussed, along with examples of how these systems are used for both novel security applications and for the detection of contraband materials at ports and borders. Differences between transmission and backscatter images will also be highlighted. In addition, tradeoffs between Compton backscatter image quality and scan speed, effective penetration, and X-ray source specifications will be discussed.

  7. Alpha proton x ray spectrometer

    Science.gov (United States)

    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.

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... for more information about pregnancy and x-rays. A Word About Minimizing Radiation Exposure Special care is ... encourage linking to this site. × Recommend RadiologyInfo to a friend Send to (friend's e-mail address): From ( ...

  9. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician ... An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treat medical conditions. ...

  10. Soft X-ray induced damage in PVA-based membranes in water environment monitored by X-ray absorption spectroscopy

    Science.gov (United States)

    Tzvetkov, George; Späth, Andreas; Fink, Rainer H.

    2014-10-01

    The effect of synchrotron X-ray flux in a soft X-ray scanning-transmission microspectroscope (STXM) instrument on the chemical structure of air-filled poly(vinyl alcohol) (PVA) based microbubbles and their stabilizing shell has been examined. Prolonged soft X-ray illumination of the particles in aqueous suspension leads to the breaking of the microbubbles' protective polymer shell and substantial chemical changes. The latter were clarified via a micro-spot C K-edge near-edge X-ray absorption fine structure (NEXAFS) spectroscopy with further respect to the absorbed X-ray doses. Our results revealed a continuous degradation of the PVA network associated with formation of carbonyl- and carboxyl-containing species as well as an increased content of unsaturated bonds. The observed effects must be taken into account in studies of micro- and nanostructured polymer materials utilizing X-rays.

  11. Surface tension and related thermodynamic quantities of aqueous electrolyte solutions

    CERN Document Server

    Matubayasi, Norihiro

    2013-01-01

    Surface tension provides a thermodynamic avenue for analyzing systems in equilibrium and formulating phenomenological explanations for the behavior of constituent molecules in the surface region. While there are extensive experimental observations and established ideas regarding desorption of ions from the surfaces of aqueous salt solutions, a more successful discussion of the theory has recently emerged, which allows the quantitative calculation of the distribution of ions in the surface region. Surface Tension and Related Thermodynamic Quantities of Aqueous Electrolyte Solutions provides a d

  12. An in-situ X-ray absorption spectroelectrochemical study of the electroreduction of uranium ions in HCl, HNO{sub 3}, and Na{sub 2}CO{sub 3} solutions

    Energy Technology Data Exchange (ETDEWEB)

    Uehara, Akihiro; Fujii, Toshiyuki; Yamana, Hajimu [Kyoto Univ., Osaka (Japan). Div. of Nuclear Engineering Science; Okamoto, Yoshihiro [Japan Atomic Energy Agency, Ibaraki (Japan). Quantum Beam Science Directorate

    2016-04-01

    A spectroelectrochemical cell was fabricated for in-situ X-ray absorption spectroscopy (in-situ XAS). The XAS spectra of the uranium L{sub III} edge were monitored in electrolyte solutions during the electrochemical reduction. Tetravalent uranium, U{sup 4+}, in 1 mol dm{sup -3} (M) hydrochloric acid (HCl) was electrochemically prepared from hexavalent uranium, UO{sub 2}{sup 2+}, by constant current electrolysis, and the extended X-ray absorption fine structure (EXAFS) was analyzed. The concentration ratio of UO{sub 2}{sup 2+} and U{sup 4+}, which were formed via the disproportionation of pentavalent uranium, UO{sub 2}{sup +}, during the electrolysis, were calculated based on the intensity of the signal for the two axial oxygen atoms in the linear UO{sub 2}{sup 2+} unit, the U-O{sub ax}, bond that had a radial structural function. The apparent redox potential of the UO{sub 2}{sup 2+}/U{sup 4+} couple in 1 M HCl was determined based on the Nernst equation using the concentrations of UO{sub 2}{sup 2+} and U{sup 4+}. The electrode potential was shown to be close to the formal potential of the UO{sub 2}{sup 2+}/UO{sub 2}{sup +} couple as reported previously. This result indicates that the UO{sub 2}{sup +} that was formed electrochemically at the electrode disproportionated to form UO{sub 2}{sup 2+} and U{sup 4+} in the bulk solution. The in-situ XAS of UO{sub 2}{sup 2+} in 0.1 M nitric acid was also performed. The U{sup 4+} that formed was partially re-oxidized to UO{sub 2}{sup 2+} by the NO{sub 3}{sup -} present in the solution. The formation of the UO{sub 2}{sup +} carbonato complex was observed by in-situ XAS in a 1 M sodium carbonate solution during the bulk electrolysis. The edge jump of the X-ray absorption near edge structure (XANES) spectrum shifted from 17.164 to 17.163 keV, and the bond distances of U-O{sub ax} and U-O for CO{sub 3}{sup 2-} increased from 1.78 to 1.88 Aa and from 2.42 to 2.53 Aa, respectively, because of the reduction of the UO{sub 2}{sup 2

  13. Micellar Packing in Aqueous Solutions of As-Received and Pure Pluronic Block Copolymers

    Science.gov (United States)

    Ryu, Chang; Park, Han Jin

    2013-03-01

    Pluronic block copolymers (Pluronics) are produced on a commercial scale to enable wide range of novel applications from emulsification and colloidal stabilization as nonionic surfactants. While the Pluronic block copolymers offer the advantages of being readily available for such applications, it contains non-micellizable low molecular weight (MW) impurities that would interfere with the self-assembly and micellar packing of PEO-PPO-PEO triblock copolymers in aqueous solutions. The impacts of the low MW impurities will be discussed on the micellar packing of Pluronics F108 and F127 solutions, which form BCC and FCC. While as-received Pluronic samples typically contain about 20 wt.% low MW impurities, we were able to reduce the impurity level to less than 2 wt.% using our large scale purification technique. Comparative studies on small angle x-ray scattering (SAXS) experiments on as-received and purified Pluronics solutions revealed that the contents of triblock copolymers in solutions essentially governs the inter-micellar distance of Pluronic cubic structures. A universal relationship between triblock copolymer concentration and SAXS-based domain spacing has been finally discussed. Funding from Agency for Defense Development, Korea.

  14. High-Resolution X-ray Emission and X-ray Absorption Spectroscopy

    OpenAIRE

    de Groot, F. M. F.

    2001-01-01

    In this review, high-resolution X-ray emission and X-ray absorption spectroscopy will be discussed. The focus is on the 3d transition-metal systems. To understand high-resolution X-ray emission and reso-nant X-ray emission, it is first necessary to spend some time discussing the X-ray absorption process. Section II discusses 1s X-ray absorption, i.e., the K edges, and section III deals with 2p X-ray absorption, the L edges. X-ray emission is discussed in, respectively, the L edges. X-ray emis...

  15. Monochromatic wavelength dispersive x-ray fluorescence providing sensitive and selective detection of uranium

    Energy Technology Data Exchange (ETDEWEB)

    Havrilla, George J [Los Alamos National Laboratory; Collins, Michael L [Los Alamos National Laboratory; Montoya, Velma M [Los Alamos National Laboratory; Chen, Zewu [XOS; Wei, Fuzhong [XOS

    2010-01-01

    Monochromatic wavelength dispersive X-ray fluorescence (MWDXRF) is a sensitive and selective method for elemental compositional analyses. The basis for this instrumental advance is the doubly curved crystal (DCC) optic. Previous work has demonstrated the feasibility of sensitive trace element detection for yttrium as a surrogate for curium in aqueous solutions. Additional measurements have demonstrated similar sensitivity in several different matrix environments which attests to the selectivity of the DCC optic as well as the capabilities of the MWDXRF concept. The objective of this effort is to develop an improved Pu characterization method for nuclear fuel reprocessing plants. The MWDXRF prototype instrument is the second step in a multi-year effort to achieve an improved Pu assay. This work will describe a prototype MWDXRF instrument designed for uranium detection and characterization. The prototype consists of an X-ray tube with a rhodium anode and a DCC excitation optic incorporated into the source. The DCC optic passes the RhK{alpha} line at 20.214 keV for monochromatic excitation of the sample. The source is capable of 50 W power at 50 kV and 1.0 mA operation. The x-ray emission from the sample is collected by a DCC optic set at the UL{alpha} line of 13.613 keV. The collection optic transmits the UL{alpha} x-rays to the silicon drift detector. The x-ray source, sample, collection optic and detector are all mounted on motion controlled stages for the critical alignment of these components. The sensitivity and selectivity of the instrument is obtained through the monochromatic excitation and the monochromatic detection. The prototype instrument performance has a demonstrated for sensitivity for uranium detection of around 2 ppm at the current state of development. Further improvement in sensitivity is expected with more detailed alignment.

  16. The effect of aqueous solution in Raman spectroscopy

    Science.gov (United States)

    Kang, Jian; Yuan, Xiaojuan; Dong, Xiao; Gu, Huaimin

    2009-08-01

    In Raman detection, the most popular solution for the samples is tri-distilled water. But the effect of aqueous solution is barely studied in Raman spectroscopy. In fact Raman spectroscopy of solid-state and liquid-state are obvious different. In addition, FWHM of Raman spectral peaks also change evidently. In this paper, several samples were selected for the experiment; including sodium nitrate, sodium nitrite, glucose and caffeine. By comparing the Raman spectroscopy of samples at different concentrations, it is found that the concentration of the sample can affect the strength of Raman spectroscopy, but it can hardly impact FWHM of Raman spectral peaks. By comparing the Raman spectroscopy of liquid-state with the Raman spectroscopy of solid-state, it is observed that the FWHM of some Raman spectral peaks varied obviously; that may be because when the sample was dissolved into the water, the crystal lattice structure was broken, and for some samples atom form became ion form in aqueous solution. Those structural variations caused the variation of the FWHM. The Raman spectroscopy of caffeine aqueous solution at very low concentration was also detected and analyzed. Compared with the Raman spectra of solid-state samples, it is found that some Raman spectral peaks disappeared when the sample was dissolved in water. It is possible that the low concentration of the sample result in the weakening of Raman signals and the disappearing of some weak Raman spectral peaks. Then Ag nanoparticles were added into the caffeine aqueous solution, the results suggest that surface enhanced Raman spectroscopy (SERS) not only can enhance the Raman spectral signal, but also can reduce the effect of aqueous solution. It is concluded that the concentration of sample only affects the strength of Raman spectroscopy; the aqueous solution can affect the FWHM of Raman spectral peaks; and SERS can reduce the effect of aqueous solution.

  17. X-Ray Spectroscopy of the Liquid Water Surface

    Science.gov (United States)

    Saykally, Richard

    2004-03-01

    We have developed a new experiment for probing molecular details of liquid-vapor interfaces of volatile substances and their solutions under equilibrium conditions. Electronic and geometric structures of interfacial molecules are probed by EXAFS and NEXAFS methods in the soft X-ray region, using the Advanced Light Source, Berkeley, CA. Liquids are introduced into a high vacuum environment through the use of liquid microjets, which have been characterized independently by Raman spectroscopy. Detection of ions and electrons produced by the Auger avalanche probe the bulk and surface regions of the microjet, respectively, as a result of their different escape depths. Our first efforts involved a comparative study of the interfaces of water and methanol, wherein we detailed the first observation of surface relaxation for a liquid. Analysis of EXAFS data yielded a 6distance at the water interface, whereas a 5was found for methanol. NEXAFS measurements, interpreted in terms of density functional theory simulations, indicate a large population of interfacial water molecules having two free OH bonds ("acceptor only molecules"). This complements the "single donor" species identified in sum frequency generation experiments. These results are supported by recent theoretical calculations. For methanol and other simple alcohols, the data indicate that free alkyl groups extend into the vapor part of the interface. Preliminary results for aqueous solutions, as well as for other pure liquids, have been obtained and are presently under analysis. REFERENCES 1. K.R. Wilson, R.D. Schaller, B.S. Rude, T. Catalano, D.T. Co, J.D. Bozek, and R.J. Saykally, "Surface relaxation in liquid water and methanol studied by X-ray absorption spectroscopy," J. Chem. Phys 117,7738(2002). 2. K.R. Wilson, M. Cavalleri, B.S. Rude, R.D. Schaller, A. Nilsson, L.G.M. Pettersson, N. Goldman, T. Catalano, J.D. Bozek, and R.J. Saykally, "Characterization of hydrogen bond acceptor molecules at the water surface

  18. Removal of Cu2+from Aqueous Solutions Using Na-A Zeolite from Oil Shale Ash

    Institute of Scientific and Technical Information of China (English)

    包维维; 刘璐; 邹海峰; 甘树才; 徐学纯; 季桂娟; 高桂梅; 郑克岩

    2013-01-01

    Na-A zeolite was synthesized using oil shale ash (OSA), which is a solid by-product of oil shale proc-essing. The samples were characterized by various techniques, such as scanning electron microscopy, X-ray diffrac-tion and Brunauer Emmet Teller method. The batch isothermal equilibrium adsorption experiments were performed to evaluate the ability of Na-A zeolite for removal of Cu (II) from aqueous solutions. The effects of operating pa-rameters, such as concentration of copper solutions, adsorbent dosages, pH value of solutions and temperature, on the adsorption efficiency were investigated. The equilibrium adsorption data were fitted with Langmuir and Freundlich models. The maximum adsorption capacity of Na-A zeolite obtained from the Langmuir adsorption iso-therm is 156.7 mg·g−1 of Cu (II). The increase of pH level in the adsorption process suggests that the uptake of heavy metals on the zeolite follows an ion exchange mechanism. The batch kinetic data fit the pseudo-second order equation well. The thermodynamic parameters, such as changes in Gibbs free energy (ΔG), enthalpy (ΔH) and en-tropy (ΔS), are used to predict the nature of the adsorption process. The negativeΔG values at different tempera-tures confirm that the adsorption processes are spontaneous.

  19. Removal of heavy metal ions from aqueous solution using red loess as an adsorbent.

    Science.gov (United States)

    Xing, Shengtao; Zhao, Meiqing; Ma, Zichuan

    2011-01-01

    The adsorption behaviors of heavy metals onto novel low-cost adsorbent, red loess, were investigated. Red loess was characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectra. The results indicated that red loess mainly consisted of silicate, ferric and aluminum oxides. Solution pH, adsorbent dosage, initial metal concentration, contact time and temperature significantly influenced the efficiency of heavy metals removal. The adsorption reached equilibrium at 4 hr, and the experimental equilibrium data were fitted to Langmuir monolayer adsorption model. The adsorption of Cu(II) and Zn(II) onto red loess was endothermic, while the adsorption of Pb(II) was exothermic. The maximum adsorption capacities of red loess for Pb(II), Cu(II) and Zn(II) were estimated to be 113.6, 34.2 and 17.5 mg/g, respectively at 25 degrees C and pH 6. The maximum removal efficiencies were 100% for Pb(II) at pH 7, 100% for Cu(II) at pH 8, and 80% for Zn(II) at pH 8. The used adsorbents were readily regenerated using dilute HCl solution, indicating that red loess has a high reusability. All the above results demonstrated that red loess could be used as a possible alternative low-cost adsorbent for the removal of heavy metals from aqueous solution.

  20. Adsorption of {sup 60}Co{sup 2+} on hydrous manganese oxide powder from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Granados Correa, F. [Inst. Nacional de Investigaciones Nucleares, Mexico (Mexico); Univ. Autonoma Metropolitana Iztapalapa, Mexico (Mexico); Jimenez-Becerril, J. [Inst. Nacional de Investigaciones Nucleares, Mexico (Mexico)

    2004-07-01

    Hydrous manganese oxide (HMO) was synthesized and its ability to sorb {sup 60}Co{sup 2+} from aqueous solution was studied under static conditions as a function of contact time, cobalt concentration (10{sup -2}-10{sup -7} M), temperature (303-333 K) and pH of adsorptive solution (2.2-11.4). X-ray diffraction was used in characterization of synthesized HMO. Low concentration of {sup 60}Co{sup 2+} solution, high pH and high temperature were the most favorable conditions for the adsorption process. The results show that the removal process is complete in 40 minutes, obeys a first order rate law and can be described using the Freundlich adsorption model. The standard enthalpy of the system was {delta}H{sup 0} = 12.5 {+-} 0.2 kJ mol{sup -1} and cobalt desorption indicates that the uptake process proceeds via cation exchange. The removal of cobalt ions by HMO appears to be endothermic and irreversible. The values of calculated {delta}G{sup 0} and {delta}S{sup 0} were -17.0 {+-} 3.0 kJ mol{sup -1} and (9.8 {+-} 0.2) x 10{sup -2} kJ K{sup -1} mol{sup -1} respectively, this indicates spontaneity of the process and the degree of freedom of ions is increased by adsorption. (orig.)

  1. Removal of heavy metal ions from aqueous solution using red loess as an adsorbent

    Institute of Scientific and Technical Information of China (English)

    Shengtao Xing; Meiqing Zhao; Zichuan Ma

    2011-01-01

    The adsorption behaviors of heavy metals onto novel low-cost adsorbent,red loess,were investigated.Red loess was characterized by X-ray diffraction,scanning electron microscopy and Fourier transform infrared spectra.The results indicated that red loess mainly consisted of silicate,ferric and aluminum oxides.Solution pH,adsorbent dosage,initial metal concentration,contact time and temperature significantly influenced the efficiency of heavy metals removal.The adsorption reached equilibrium at 4 hr,and the experimental equilibrium data were fitted to Langmuir monolayer adsorption model.The adsorption of Cu(Ⅱ) and Zn(Ⅱ) onto red loess was endothermic,while the adsorption of Pb(Ⅱ) was exothermic.The maximum adsorption capacities of red loess for Pb(Ⅱ),Cu(Ⅱ)and Zn(Ⅱ) were estimated to be 113.6,34.2 and 17.5 mg/g,respectively at 25°C and pH 6.The maximum removal efficiencies were 100% for Pb(Ⅱ) at pH 7,100% for Cu(Ⅱ) at pH 8,and 80% for Zn(Ⅱ) at pH 8.The used adsorbents were readily regenerated using dilute HCI solution,indicating that red loess has a high reusability.All the above results demonstrated that red loess could be used as a possible alternative low-cost adsorbent for the removal of heavy metals from aqueous solution.

  2. Wet etching of InSb surfaces in aqueous solutions: Controlled oxide formation

    Energy Technology Data Exchange (ETDEWEB)

    Aureau, D., E-mail: damien.aureau@chimie.uvsq.fr [Institut Lavoisier UVSQ-CNRS UMR 8180, 45 avenue des Etats Unis, Versailles, 78035 (France); Chaghi, R.; Gerard, I. [Institut Lavoisier UVSQ-CNRS UMR 8180, 45 avenue des Etats Unis, Versailles, 78035 (France); Sik, H.; Fleury, J. [Sagem Defense Sécurité, 72-74, rue de la tour Billy, 95101, Argenteuil Cedex (France); Etcheberry, A. [Institut Lavoisier UVSQ-CNRS UMR 8180, 45 avenue des Etats Unis, Versailles, 78035 (France)

    2013-07-01

    This paper investigates the wet etching of InSb surfaces by two different oxidant agents: Br{sub 2} and H{sub 2}O{sub 2} and the consecutive oxides generation onto the surfaces. The strong dependence between the chemical composition of the etching baths and the nature of the final surface chemistry of this low band-gap III–V semiconductor will be especially highlighted. One aqueous etching solution combined hydrobromic acid and Bromine (HBr–Br{sub 2}:H{sub 2}O) with adjusted concentrations. The other solution combines orthophosphoric and citric acids with hydrogen peroxide (H{sub 3}PO{sub 4}–H{sub 2}O{sub 2}:H{sub 2}O). Depending on its composition, each formulation gave rise to variable etching rate. The dosage of Indium traces in the etching solution by atomic absorption spectroscopy (AAS) gives the kinetic variation of the dissolution process. The variations on etching rates are associated to the properties and the nature of the formed oxides on InSb surfaces. Surface characterization is specifically performed by X-ray photoelectron spectroscopy (XPS). A clear evidence of the differences between the formed oxides is highlighted. Atomic force microscopy is used to monitor the surface morphology and pointed out that very different final morphologies can be reached. This paper presents new results on the strong variability of the InSb oxides in relation with the InSb reactivity toward environment interaction.

  3. Aviation security x-ray detection challenges

    Science.gov (United States)

    Harvey, T.

    2016-05-01

    In this paper, a review of the background and some drivers are provided for X-ray screening for aviation security. Some of the key considerations are highlighted along with impacts of the image-based approaches and signature approaches. The role of information theory is discussed along with some recent work that may influence the technical direction by posing the question: "what measurements, parameters and metrics should be considered in future system design?" A path forward should be based on information theory, however electronic machines will likely interface with humans and be dollar-cost driven, so ultimately solutions must consider additional parameters other than only technical performance factors.

  4. [Synthesis of hydroxyapatite/magnetite/zeolite composite for Congo red removal from aqueous solution].

    Science.gov (United States)

    Fang, Qiao; Lin, Jian-Wei; Zhan, Yan-Hui; Yang, Meng-Juan; Zheng, Wen-Jing

    2014-08-01

    In this study, a novel hydroxyapatite/magnetite/zeolite (HAP/Fe3O4/Zeo) composite was prepared, characterized and used as an adsorbent to remove Congo red (CR) from aqueous solution. The adsorption characteristics of CR from aqueous solution on the HAP/Fe3O4/Zeo composite were investigated using batch experiments. Results showed that the HAP/Fe3O4/Zeo composite was effective for the removal of CR from aqueous solution. The CR adsorption capacity for the HAP/Fe3O4/Zeo composite decreased with solution pH increasing from 3 to 4 or solution pH increasing from 7 to 11, and remained basically unchanged with pH increasing from 4 to 7. The CR removal efficiency of the HAP/Fe3O4/Zeo composite increased with increasing adsorbent dosage, while the amount of CR adsorbed on the HAP/Fe3O4/Zeo composite decreased with increasing adsorbent dosage. The adsorption kinetic data of CR on the HAP/Fe3O4/Zeo composite well fitted a pseudo-second-order model. The equilibrium adsorption data of CR on the HAP/Fe3O4/Zeo composite could be described by the Langmuir and Freundlich isotherm models. The maximum monolayer adsorption capacity for CR derived from the Langmuir isotherm model was determined to be 117 mg x g(-1) at pH 7 and 303 K. The adsorption process of CR on the HAP/Fe3O4/Zeo composite was spontaneous and endothermic. The main mechanisms for the adsorption of CR on the HAP/Fe3O4/Zeo composite at pH 7 included surface complexation, hydrogen bonding and Lewis acid-base reaction. Thermal regeneration showed that the HAP/Fe3O4/Zeo composite could be used for five desorption-adsorption cycles with high removal efficiency for CR in each cycle. X-ray diffraction (XRD) analysis revealed that the HAP/Fe3O4/zeolite composite contained Fe3O4, and this composite had relatively high saturation magnetization. The HAP/Fe3O4/Zeo composite adsorbed with CR could be collected from aqueous solution under an external magnetic field quickly. Results of this study suggested that the HAP/Fe3O4/Zeo

  5. Protein structure validation and analysis with X-ray crystallography.

    Science.gov (United States)

    Papageorgiou, Anastassios C; Mattsson, Jesse

    2014-01-01

    X-ray crystallography is the main technique for the determination of protein structures. About 85 % of all protein structures known to date have been elucidated using X-ray crystallography. Knowledge of the three-dimensional structure of proteins can be used in various applications in biotechnology, biomedicine, drug design, and basic research and as a validation tool for protein modifications, ligand binding, and structural authenticity. Moreover, the requirement for pure, homogeneous, and stable protein solutions in crystallizations makes X-ray crystallography beneficial in other fields of protein research as well. Here, we describe the technique of X-ray protein crystallography and the steps involved for a successful three-dimensional crystal structure determination.

  6. Solution behaviors and microstructures of PNIPAm-P123-PNIPAm pentablock terpolymers in dilute and concentrated aqueous solutions.

    Science.gov (United States)

    Lu, Yanping; Chen, Tongquan; Mei, Aixiong; Chen, Tianyou; Ding, Yanwei; Zhang, Xinghong; Xu, Junting; Fan, Zhiqiang; Du, Binyang

    2013-06-07

    The solution behaviors and microstructures of poly(N-isopropylacrylamide)x-poly(ethylene oxide)20-poly(propylene oxide)70-poly(ethylene oxide)20-poly(N-isopropylacrylamide)x (PNIPAmx-PEO20-PPO70-PEO20-PNIPAmx or PNIPAmx-P123-PNIPAmx) pentablock terpolymers with various PNIPAm block lengths in dilute and concentrated aqueous solutions were investigated by micro-differential scanning calorimetry (micro-DSC), static and dynamic light scattering (SLS & DLS), and synchrotron small angle X-ray scattering (SAXS). Two lower critical solution temperatures (LCSTs) were observed for PNIPAmx-P123-PNIPAmx pentablock terpolymers in dilute solutions, which corresponded to LCSTs of PPO and PNIPAm blocks, respectively. The LCST of PPO block shifted from 24.4 °C to 29 °C when the length x of PNIPAm block increased from 10 to 97. The LCST of PNIPAm is around 34.5 °C-35.3 °C and less dependent on the block length x. The PNIPAmx-P123-PNIPAmx pentablock terpolymers formed "associate" structures and micelles with hydrophobic PNIPAm and PPO blocks as cores and soluble PEO blocks as coronas in dilute aqueous solutions at 20 °C and 40 °C, respectively, regardless of the relative lengths of PNIPAm, PPO and PEO blocks. The size of "associate" structures of PNIPAmx-P123-PNIPAmx pentablock terpolymers at 20 °C increased with increasing the length of PNIPAm block. The microstructures of PNIPAmx-P123-PNIPAmx hydrogels formed in concentrated aqueous solutions (40 wt%) were strongly dependent on the environmental temperatures and relative lengths of PNIPAm, PPO and PEO blocks as revealed by SAXS. Increasing the length of PNIPAm block weakened the order structures of PNIPAmx-P123-PNIPAmx hydrogels. The microstructures of PNIPAmx-P123-PNIPAmx hydrogels changed from mixed fcc and hex structures for PNIPAm10-P123-PNIPAm10 to isotropic structure for PNIPAm97-P123-PNIPAm97. Increasing temperature led to the transition from mixed hex and fcc structure to pure hex structure for PNIPAm10-P123-PNIPAm

  7. Adsorption of As(III) from Aqueous Solutions by Novel Fe-Mg Type Hydrotalcite.

    Science.gov (United States)

    Ogata, Fumihiko; Kawasaki, Naohito

    2015-01-01

    Morphological and chemical evaluation of Fe-Mg hydrotalcite (Fe-HT) was performed using scanning electron microscopy, X-ray diffraction analysis, and electron microanalysis for application as an adsorbent for water treatment. The adsorption of arsenic III (As(III)) on Fe-HT was evaluated via examination of the effect of the contact time and analysis of the adsorption isotherm. The amount of As(III) adsorbed increased slightly with increasing temperature. The results of the adsorption isotherm studies suggested that As(III) adsorption can be well described by both the Freundlich and Langmuir equations. The adsorption of As(III) on Fe-HT reached equilibrium within 24 h, and the adsorption kinetic data fit the pseudo-second-order kinetic model better than the pseudo-first-order model. The amount of As(III) present on the surface of Fe-HT increased after As(III) adsorption, and the crystalline structure of Fe-HT was maintained after adsorption of As(III). The (003) and (006) peaks in the X-ray diffraction patterns were attributed to basal reflections, and these peaks shifted from respective 2θ values of 10.86 and 21.94° to 11.12 and 22.52°, indicating exchange of As(III) with chloride ions in Fe-HT with consequent narrowing of the inter-layer spacing. Collectively, these results suggest that Fe-HT is prospectively useful for the adsorption of As(III) from aqueous solutions.

  8. Use of 3-aminopropyltriethoxysilane deposited from aqueous solution for surface modification of III-V materials

    Science.gov (United States)

    Knorr, Daniel B., Jr.; Williams, Kristen S.; Baril, Neil F.; Weiland, Conan; Andzelm, Jan W.; Lenhart, Joseph L.; Woicik, Joseph C.; Fischer, Daniel A.; Tidrow, Meimei Z.; Bandara, Sumith V.; Henry, Nathan C.

    2014-11-01

    Focal plane arrays of strained layer superlattices (SLSs) composed of InAs/GaSb are excellent candidates for infrared imaging, but one key factor limiting their utility is the lack of a surface passivation technique capable of protecting the mesa sidewall from degradation. Along these lines, we demonstrate the use of aqueous 3-aminopropyl triethoxysilane (APTES) deposited as a surface functionalizing agent for subsequent polymer passivation on InAs and GaSb surfaces following a HCl/citric acid procedure to remove the conductive oxide In2O3. Using atomic force microscopy, variable angle spectroscopic ellipsometry, X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS), and modeling with density functional theory (DFT), we demonstrate that APTES films can successfully be deposited on III-V substrates by spin coating and directly compare these films to those deposited on silicon substrates. The HCl/citric acid surface preparation treatment is particularly effective at removing In2O3 without the surface segregation of In oxides observed from use of HCl alone. However, HCl/citric acid surface treatment method does result in heavy oxidation of both Ga and Sb, accompanied by segregation of Ga oxide to the surface. Deposited APTES layer thickness did not depend on the substrate choice, and thicknesses between 1 and 20 nm were obtained for APTES solution concentrations ranging from 0.1 to 2.5 vol %. XPS results for the N1s band of APTES showed that the content of ionic nitrogen was high (∼50%) for the thinnest films (∼1 nm), and decreased with increasing film thickness. These results indicate that APTES can indeed be used to form a silane surface layer to cover III-V materials substrates. Such APTES silane layers may prove useful in surface passivation of these materials alone, or as surface functionalizing agents for subsequent covalent binding with polymer overlayers like polyimide.

  9. Application of Fe-Cu binary oxide nanoparticles for the removal of hexavalent chromium from aqueous solution.

    Science.gov (United States)

    Khan, Saif Ullah; Zaidi, Rumman; Hassan, Saeikh Z; Farooqi, I H; Azam, Ameer

    2016-01-01

    The adsorption process has been used as an effective technique for the removal of metal ions from aqueous solutions. Groundwater remediation by nanoparticles has received interest in recent years. In the present study, a binary metal oxide of Fe-Cu was prepared and used for the removal of hexavalent chromium from aqueous solution. Batch experiments were performed to investigate the effects of initial Cr (VI) concentration, dose of adsorbent, and pH of solution on the removal efficiency of Cr (VI). The prepared nanostructured Fe-Cu binary oxides were able to reduce the concentration of Cr (VI) in aqueous solution. Binary metal oxides nanoparticle exhibited an outstanding ability to remove Cr (VI) due to high surface area, low particle size, and high inherent activity. The percentage removal efficiency of Cr (VI) increased with nanoparticles doses (0.1 g L(-1)-2.5 g L(-1)), whereas it decreased with initial Cr (VI) concentration (1 mg L(-1)-25 mg L(-1)) and with pH (3-9). The Freundlich model was found to be the better fit for adsorption isotherm. The prepared nanomaterial was characterized using powder X-ray diffraction, scanning electron microscopy (SEM), and ultraviolet (UV)-visible spectroscopy. It showed that the Fe-Cu binary oxides were formed in single phase. SEM micrograph showed aggregates with many nano-sized particles. UV-visible spectroscopy showed quantum confinement effect.

  10. Phosphate removal from aqueous solutions by nanoscale zero-valent iron.

    Science.gov (United States)

    Wu, Donglei; Shen, Yanhong; Ding, Aqiang; Qiu, Mengyu; Yang, Qi; Zheng, Shuangshuang

    2013-01-01

    In this study, nanoscale zero-valent iron (NZVI) was synthesized by conventional liquid-phase chemical reduction methods without a support material and then characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of NZVI particles on phosphate removal from aqueous solutions was examined. The results showed that the phosphate removal efficiency increased from 34.49% to 87.01% as the dosage of nanoscale iron particles increased from 100 to 600 mg L(-1) with an initial phosphate concentration of 10 mg L(-1), and the phosphate removal efficiency decreased from 72.89% to 51.39% as the initial phosphate concentration increased from 10 to 90 mg L(-1), with 400 mg L(-1) NZVI. Phosphate removal efficiencies of 99.41% and 95.09% were achieved at pH values of 2 and 4, respectively, with an initial phosphate concentration of 20 mg L(-1) and 400mg L(-1) NZVI. The use of NZVI particles synthesized in a carboxymethyl cellulose (CMC)-water solution significantly enhanced phosphate removal from an aqueous solution compared with the use of NZVI synthesized in an ethanol-water solution. NZVI particles achieved 71.34% phosphate removal, which was remarkably higher than that of microscale zero-valent iron (MZVI) particles (16.35%) with 10 mg L(-1) of phosphate and 400mg L(-1) iron. Based on the removal mechanism analysis performed in this study, we recommend that phosphate removal be accomplished by simultaneous adsorption and chemical precipitation. The XRD patterns of the NZVI before and after the reactions indicated the formation of crystalline vivianite (Fe3(PO4)2 x 8H2O) during the procedure.

  11. Aqueous solutions at the interface with phospholipid bilayers.

    Science.gov (United States)

    Berkowitz, Max L; Vácha, Robert

    2012-01-17

    In a sense, life is defined by membranes, because they delineate the barrier between the living cell and its surroundings. Membranes are also essential for regulating the machinery of life throughout many interfaces within the cell's interior. A large number of experimental, computational, and theoretical studies have demonstrated how the properties of water and ionic aqueous solutions change due to the vicinity of membranes and, in turn, how the properties of membranes depend on the presence of aqueous solutions. Consequently, understanding the character of aqueous solutions at their interface with biological membranes is critical to research progress on many fronts. The importance of incorporating a molecular-level description of water into the study of biomembrane surfaces was demonstrated by an examination of the interaction between phospholipid bilayers that can serve as model biological membranes. The results showed that, in addition to well-known forces, such as van der Waals and screened Coulomb, one has to consider a repulsion force due to the removal of water between surfaces. It was also known that physicochemical properties of biological membranes are strongly influenced by the specific character of the ions in the surrounding aqueous solutions because of the observation that different anions produce different effects on muscle twitch tension. In this Account, we describe the interaction of pure water, and also of aqueous ionic solutions, with model membranes. We show that a symbiosis of experimental and computational work over the past few years has resulted in substantial progress in the field. We now better understand the origin of the hydration force, the structural properties of water at the interface with phospholipid bilayers, and the influence of phospholipid headgroups on the dynamics of water. We also improved our knowledge of the ion-specific effect, which is observed at the interface of the phospholipid bilayer and aqueous solution, and its

  12. Acidities of Water and Methanol in Aqueous Solution and DMSO

    Science.gov (United States)

    Gao, Daqing

    2009-01-01

    The relative acidities of water and methanol have been a nagging issue. In gas phase, methanol is more acidic than water by 36.0 kJ/mol; however, in aqueous solution, the acidities of methanol and water are almost identical. The acidity of an acid in solution is determined by both the intrinsic gas-phase ionization Gibbs energy and the solvent…

  13. Synthesis and Aqueous Solution Viscosity of Hydrophobically Modified Xanthan Gum

    Institute of Scientific and Technical Information of China (English)

    QIAN Xiao-lin; WU Wen-hui; YU Pei-zhi; WANG Jian-quan

    2007-01-01

    Two xanthan gum derivatives hydrophobically modified by 4 or 8 tetradecyl chains per 100 xanthan gum structure units were synthesized. The derivatives were studied by scanning electron microscope and pyrene fluorescence spectrometry. And the aqueous solution apparent viscosity of the derivatives was investigated. The results indicate that the network of the derivatives with more hydrophobic groups is closer and tighter. With increasing of alkyl chain substitution degree, the hydrophobically associating interactions enhance in aqueous solution. Aqueous solution apparent viscosity of the derivatives increases with increasing of polymer concentration and alkyl substitution degree, and decreases with the increase of temperature. In the brine solution, the strong viscosity enhancement phenomenon appears. The interaction between the derivatives and surfactant sodium dodecylbenzene sulfonate is strong.

  14. X-Ray-powered Macronovae

    Science.gov (United States)

    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.

  15. Be/X-ray binaries

    CERN Document Server

    Reig, Pablo

    2011-01-01

    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 transfer. Until recently, it was thought that the Be stars' disc was not significantly affected by the neutron star. In this review, I present the observational evidence accumulated in recent years on the interaction between the circumstellar disc and the compact companion. The most obvious effect is the tidal truncation of the disc. As a result, the equatorial discs in Be/X-ray binaries are smaller and denser than those around isolat...

  16. Zinc nanoparticles in solution by laser ablation technique

    Indian Academy of Sciences (India)

    S C Singh; R Gopal

    2007-06-01

    Colloidal zinc metallic nanoparticles are synthesized using pulsed laser ablation of metal plate in an aqueous solution of suitable surfactant to prevent aggregation. UV-visible absorption, TEM, small angle X-ray diffraction and wide-angle X-ray diffraction are used for the characterization of colloidal zinc metallic nanoparticles. Colloidal nanoparticles are found highly stable for a long time.

  17. Polypyrrole-polyaniline/Fe{sub 3}O{sub 4} magnetic nanocomposite for the removal of Pb(II) from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Afshar, Amirhossein; Sadjadi, Seyed Abolfazl Seyed; Mollahosseini, Afsaneh; Eskandarian, Mohammad Reza [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2016-02-15

    Lead ion which is engaged in aqueous solution has been successfully removed. A novel technique was utilized for the separation and absorption of Pb(II) ions from aqueous solution. Magnetic Fe{sub 3}O{sub 4} coated with newly investigated polypyrrole-polyaniline nanocomposite was used for the removal of extremely noxious Pb(II). Characteristic of the prepared magnetic nanocomposite was done using X-ray diffraction pattern, Field emission scanning electron microscopy (FE-SEM), Fourier transform-infrared spectroscopy (FT-IR) and energy dispersive x-ray spectroscopy (EDX). Up to 100% adsorption was found with 20mg/L Pb(II) aqueous solution in the range of pH=8-10. Adsorption results illustrated that Pb(II) removal efficiency by the nanocomposite increased with an enhance in pH. Adsorption kinetics was best expressed by the pseudo-second-order rate form. Isotherm data fitted well to the Freundlich isotherm model. Upon using HCl and HNO{sub 3}, 75% PPy-PAn/Fe{sub 3}O{sub 4} nanocomposite, desorption experiment showed that regenerated adsorbent can be reused successfully for two successive adsorption-desorption cycles without appreciable loss of its original capacity.

  18. Structure of water and the thermodynamics of aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Nemethy, G.

    1970-10-26

    This report represents the summary of a series of lectures held at the Istituto Superiore di Sanita, Laboratori di Fisica, from 18 September to 26 October 1970. The topics discussed were: Intermolecular forces, the individual water molecule and the hydrogen bond, the structures of the solid phases of water, experimental information on the strucuture of liquid water, theoretical models of water structure, experimental properties and theoretical models of aqueous solutions of nonpolar solutes, polar solutes, and electrolytes, the conformational stability of biological macromolecules.

  19. Conductivity of Oxalic Acid in Aqueous Solution at Low Concentration

    Institute of Scientific and Technical Information of China (English)

    倪良; 韩世钧

    2005-01-01

    Oxalic acid is a weak and unsymmetrical bi-basic acid. There exist dissociation and association equilibria among the species in aqueous solution. The molar conductivity of the solution is the sum of the ionic contributions.Based on this idea, a new prediction equation of ionic conductivity was proposed at low concentration. The molar conductivities of the solution and its relevant ions were calculated respectively. The results obtained were in good agreement with those from experiments and the Quint-Viallard equation.

  20. Electrochemical oxidation of pyrrhotute in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    QIN Wen-qing; LI Quan; QIU Guan-zhou; XU Ben-jun

    2005-01-01

    The anodic surface oxidation of natural pyrrhotite in 0.3 mol/L KCl and HCl solution (pH 4. 0) and 0.1 mol/L Na2 B4O7 solution (pH 9.18) respectively was investigated by using cyclic voltammetry, Tafel plot, and chronoamperometry. In 0.3 mol/L KCl and HCl solution (pH 4.0), at potential less than 0.5 V(vs SHE), the production of anodic oxidation on pyrrhotite surface can not maintain a stable phase to form a passive film. In 0. 1 mol/L Na2B4 O7 solution (pH 9.18), when the electrode potential increases to more than 0.5 V (vs SHE), part of S is oxidized to sulfate, making the passive film somewhat porous, but elemental S and metal oxidates Fe(OH)3 still remain on the electrode surface, and the passive film can not be broken down totally. According to PARCalc Tafel analysis,the corresponding corrosion current density (J0) is 5.34 μA/cm2 , which is also the exchange current density of the oxidation reaction on pyrrhotite electrode surface in 0. 1 mol/L Na2B4O7 solution (pH 9.18). The electrochemical dynamics equation of the oxidation was determined.

  1. Removal of lead from aqueous solution with native and chemically modified corncobs.

    Science.gov (United States)

    Tan, Guangqun; Yuan, Hongyan; Liu, Yong; Xiao, Dan

    2010-02-15

    In this study, corncobs biomass was utilized as an adsorbent to remove Pb(II) from aqueous solution. The adsorption behavior of Pb(II) was studied under different conditions, including solution pH, contact time and metal concentration. Ground corncobs were modified with CH(3)OH and NaOH to investigate the effect of chemical modification on Pb(II) binding capacity. Results showed that Pb(II) binding on the biomass is pH-dependent and the kinetics can be well described by the Lagergren-second-order model. The maximum Pb(II) binding capacity q(max) calculated from Langmuir isotherm was 0.0783 mmol/g. After base hydrolysis of the biomass, Pb(II) binding capacity increased from 0.0783 to 0.2095 mmol/g (about 43.4 mg Pb/g). However, Pb(II) binding capacity on the esterified corncobs decreased greatly from 0.0783 to 0.0381 mmol/g. Fourier transform infrared spectroscopy (FTIR) analysis showed that hydroxyl and carboxylic (COO(-)) groups on the biomass play an important role in Pb(II) binding process. The X-ray photoelectron spectroscopy (XPS) data further indicated that lead is adsorbed as Pb(2+) and is attached to oxide groups on the biomass.

  2. Morphology of modified biochar and its potential for phenol removal from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Kostas A. Komnitsas

    2016-04-01

    Full Text Available In the present study, the efficiency of phenol removal from synthetic aqueous solutions by chemically modified biochar with the use of 1M KOH or 1M FeCl3 was investigated. Initially, biochar was produced after slow pyrolysis of three different agricultural wastes, namely pistachio (Pistacia vera L. shells, pecan (Carya illinoinensis shells and wood sawdust. The quality of biochar was assessed by evaluating its main properties, such as pH, surface area, porosity and C content. X-ray diffraction (XRD, Scanning Electron Microscopy (SEM and Fourier Transform Infrared Spectroscopy (FTIR were used for the identification of biochar’s structure. The efficiency of phenol removal from synthetic solutions was assessed with the use of kinetic and equilibrium experiments. The experimental results show that the KOH-modified biochar exhibited the highest phenol removal efficiency. Hydrophobic sorption on its surface is the main phenol removal mechanism. The pseudo-second order model fits best the kinetic data, while the Freundlich model, as deduced from an equilibrium study describes very well sorption of phenols on all biochars examined.

  3. THE REMOVAL OF REACTIVE RED 228 DYE FROM AQUEOUS SOLUTIONS BY CHITOSAN-MODIFIED FLAX SHIVE

    Directory of Open Access Journals (Sweden)

    Hao Feng,

    2011-12-01

    Full Text Available Flax shive (FS is a byproduct from flax fiber separation. The use of absorbent prepared from chitosan-modified flax shive (CFS has been studied for removal of reactive red dye (RR228 from aqueous solutions. CFS was characterized by the Brunauer-Emmett-Teller (BET method, Scanning Electron Microscopy (SEM, Fourier Transform Infrared spectrometry (FTIR, and X-ray photoelectron spectroscopy (XPS. A batch adsorption study was conducted under various contact time, initial concentration, solution pH, and adsorbent dosage. It was found that the BET and Langmuir surface area of CFS were 1.772 m2 g-1 and 3.057 m2 g-1, respectively. Results showed that CFS has the same pores as FS and that the –NH2 group on CFS is the main adsorption site for dye sorption. Equilibrium adsorption capacity could be reached within 480 min, and RR228 uptake was satisfactory at a pH of 2.0. The percentage removal were 100%, 100%, 90%, and 85% at pH 2.0 under dye concentrations of 10 mg/L, 20 mg/L, 30 mg/L, and 40 mg/L, respectively. The adsorption accurately fitted a pseudo-second-order kinetic model and a Langmuir isotherm model. It is proposed that CFS could be applied as a low-cost absorbent in removal of dyes from wastewater.

  4. Removal of arsenate and arsenite from aqueous solution by waste cast iron.

    Science.gov (United States)

    Choi, Nag-Choul; Kim, Song-Bae; Kim, Soon-Oh; Lee, Jae-Won; Park, Jun-Boum

    2012-01-01

    The removal of As(III) and As(V) from aqueous solution was investigated using waste cast iron, which is a byproduct of the iron casting process in foundries. Two types of waste cast iron were used in the experiment: grind precipitate dust (GPD) and cast iron shot (CIS). The X-ray diffraction analysis indicated the presence of Feo on GPD and CIS. Batch experiments were performed under different concentrations of As(III) and As(V) and at various initial pH levels. Results showed that waste cast iron was effective in the removal of arsenic. The adsorption isotherm study indicated that the Langmuir isotherm was better than the Freundlich isotherm at describing the experimental result. In the adsorption of both As(IH) and As(V), the adsorption capacity of GPD was greater than CIS, mainly due to the fact that GPD had higher surface area and weight percent of Fe than CIS. Results also indicated the removal of As(III) and As(V) by GPD and CIS was influenced by the initial solution pH, generally decreasing with increasing pH from 3.0 to 10.5. In addition, both GPD and CIS were more effective at the removal of As(III) than As(V) under given experimental conditions. This study demonstrates that waste cast iron has potential as a reactive material to treat wastewater and groundwater containing arsenic.

  5. Polymer-Controlled Growth of CuO Nanodiscs in the Mild Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    PENG Yin; LIU Zhengyin; YANG Zihui

    2009-01-01

    CuO nanodiscs have been synthesized on a large scale by a facile solution-based method using polymers as crystal growth modifiers. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and high resolu-tion transmission electron microscopy (HRTEM) were carded out to characterize the structures and morphologies of the obtained products. The effects of reaction temperature, concentrations of polyacrylamide (PAM) and reac-tants on the morphology and size of the product were studied. The results revealed that the CuO nanodisc had sin-gle-crystal monoclinic structures, and grew along (002) and (110) planes. Experimental conditions had all influence on the shape and size of the final products, but polymer PAM played the key role in formation of the CuO nanodisc.A possible growth mechanism of the CuO nanostructures based on typical polymer-crystal interactions in a mild aqueous solution was given. Polymer-directed crystal growth may provide promising routes to rational synthesis of various ordered inorganic and inorganic-organic hybrid materials with complex forms and structural specialization.

  6. Molecular Weight and Aggregation of Erwinia Gum in Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weight-average molecular weights Mw, number-average molecular weights Mn and intrinsic viscosities[η] of the four fractions and the unfractionated E gum in aqueous solutions at desired temperatures were studied by light scattering, membrane osmometry, size exclusion chromatography(SEC) and viscometry. The experimental results prove that E gum formed aggregates in the aqueous solution at 25 ℃ and the aggregates were broken gradually with increasing temperature. The dissociation of the aggregates of E gum in the aqueous solution started at 36 ℃, and was completed at around 90 ℃. The [η] values of E gum and its fractions are much higher than those of the conventional polymers with the similar molecular weights, and decrease with increasing NaCl concentration.

  7. X-ray fluorescence and energy dispersive x-ray diffraction for the quantification of elemental concentrations in breast tissue.

    Science.gov (United States)

    Geraki, K; Farquharson, M J; Bradley, D A

    2004-01-07

    This paper presents improvements on a previously reported method for the measurement of elements in breast tissue specimens (Geraki et al 2002 Phys. Med. Biol. 47 2327-39). A synchrotron-based system was used for the detection of the x-ray fluorescence (XRF) emitted from iron, copper, zinc and potassium in breast tissue specimens, healthy and cancerous. Calibration models resulting from the irradiation of standard aqueous solutions were used for the quantification of the elements. The present developments concentrate on increasing the convergence between the tissue samples and the calibration models, therefore improving accuracy. For this purpose the composition of the samples in terms of adipose and fibrous tissue was evaluated, using an energy dispersive x-ray diffraction (EDXRD) system. The relationships between the attenuation and scatter properties of the two tissue components and water were determined through Monte Carlo simulations. The results from the simulations and the EDXRD measurements allowed the XRF data from each specimen to be corrected according to its composition. The statistical analysis of the elemental concentrations of the different groups of specimens reveals that all four elements are found in elevated levels in the tumour specimens. The increase is less pronounced for iron and copper and most for potassium and zinc. Other observed features include the substantial degree of inhomogeneity of elemental distributions within the volume of the specimens, varying between 4% and 36% of the mean, depending on the element and the type of the sample. The accuracy of the technique, based on the measurement of a standard reference material, proved to be between 3% and 22% depending on the element, which presents only a marginal improvement (1%-3%) compared to the accuracy of the previously reported results. The measurement precision was between 1% and 9% while the calculated uncertainties on the final elemental concentrations ranged between 10% and 16%.

  8. Cryotomography x-ray microscopy state

    Science.gov (United States)

    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.

  9. X-Ray Exam: Scoliosis (For Parents)

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Scoliosis KidsHealth > For Parents > X-Ray Exam: Scoliosis A A A What's in ... español Radiografía: escoliosis What It Is A scoliosis X-ray is a relatively safe and painless test ...

  10. X-Ray Exam: Neck (For Parents)

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Neck KidsHealth > For Parents > X-Ray Exam: Neck A A A What's in ... español Radiografía: cuello What It Is A neck X-ray is a safe and painless test that ...

  11. X-Ray Exam: Femur (Upper Leg)

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Femur (Upper Leg) KidsHealth > For Parents > X-Ray Exam: Femur (Upper Leg) A A A ... español Radiografía: fémur What It Is A femur X-ray is a safe and painless test that ...

  12. X-Ray Exam: Cervical Spine

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Cervical Spine KidsHealth > For Parents > X-Ray Exam: Cervical Spine A A A What's ... columna cervical What It Is A cervical spine X-ray is a safe and painless test that ...

  13. Fourier-Transform Ghost Imaging with Hard X Rays

    Science.gov (United States)

    Yu, Hong; Lu, Ronghua; Han, Shensheng; Xie, Honglan; Du, Guohao; Xiao, Tiqiao; Zhu, Daming

    2016-09-01

    Knowledge gained through x-ray crystallography fostered structural determination of materials and greatly facilitated the development of modern science and technology in the past century. However, it is only applied to crystalline structures and cannot resolve noncrystalline materials. Here we demonstrate a novel lensless Fourier-transform ghost imaging method with pseudothermal hard x rays that extends x-ray crystallography to noncrystalline samples. By measuring the second-order intensity correlation function of the light, Fourier-transform diffraction pattern of a complex amplitude sample is achieved at the Fresnel region in our experiment and the amplitude and phase distributions of the sample in the spatial domain are retrieved successfully. For the first time, ghost imaging is experimentally realized with x rays. Since a highly coherent x-ray source is not required, the method can be implemented with laboratory x-ray sources and it also provides a potential solution for lensless diffraction imaging with fermions, such as neutrons and electrons where intensive coherent sources usually are not available.

  14. Oxidation of Hydrazine in Aqueous Solutions

    Science.gov (United States)

    1978-03-01

    mechanism is different in the two different temperature regions [ Levenspiel (Reference 21)]. Lurker (Reference 7) also observed that at 6°C a kinetic...and Bielski, B., Kinetic Systems: Mathematical Descriptions of Chemical Kinetics in Solution, Wiley Interscience, New York (1972). 21. Levenspiel , 0

  15. Predicting accurate absolute binding energies in aqueous solution

    DEFF Research Database (Denmark)

    Jensen, Jan Halborg

    2015-01-01

    Recent predictions of absolute binding free energies of host-guest complexes in aqueous solution using electronic structure theory have been encouraging for some systems, while other systems remain problematic. In this paper I summarize some of the many factors that could easily contribute 1-3 kcal......-represented by continuum models. While I focus on binding free energies in aqueous solution the approach also applies (with minor adjustments) to any free energy difference such as conformational or reaction free energy differences or activation free energies in any solvent....

  16. A lithium ion battery using an aqueous electrolyte solution

    OpenAIRE

    Zheng Chang; Chunyang Li; Yanfang Wang; Bingwei Chen; Lijun Fu; Yusong Zhu; Lixin Zhang; Yuping Wu; Wei Huang

    2016-01-01

    Energy and environmental pollution have become the two major problems in today’s society. The development of green energy storage devices with good safety, high reliability, high energy density and low cost are urgently demanded. Here we report on a lithium ion battery using an aqueous electrolyte solution. It is built up by using graphite coated with gel polymer membrane and LISICON as the negative electrode, and LiFePO4 in aqueous solution as the positive electrode. Its average discharge vo...

  17. Ionisation constants of inorganic acids and bases in aqueous solution

    CERN Document Server

    Perrin, D D

    2013-01-01

    Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution, Second Edition provides a compilation of tables that summarize relevant data recorded in the literature up to the end of 1980 for the ionization constants of inorganic acids and bases in aqueous solution. This book includes references to acidity functions for strong acids and bases, as well as details about the formation of polynuclear species. This text then explains the details of each column of the tables, wherein column 1 gives the name of the substance and the negative logarithm of the ionization constant and column 2

  18. Removal of Phosphate from Aqueous Solution with Modified Bentonite

    Institute of Scientific and Technical Information of China (English)

    唐艳葵; 童张法; 魏光涛; 李仲民; 梁达文

    2006-01-01

    Bentonite combined with sawdust and other metallic compounds was used to remove phosphate from aqueous solutions in this study. The adsorption characteristics of phosphate on the modified bentonite were investigated, including the effects of temperature, adsorbent dosage, initial concentration of phosphate and pH on removal of phosphate by conducting a series of batch adsorption experiments. The results showed that 98% of phosphate removal rate was obtained since sawdust and bentonite used in this investigation were abundantly and locally available. It is concluded that modified bentonite is a relatively efficient, low cost and easily available adsorbent for the removal of phosphate from aqueous solutions.

  19. [Extraction of alpha-cypermethrin from aqueous methanol solutions].

    Science.gov (United States)

    Shormanov, V K; Chigareva, E N; Belousova, O V

    2010-01-01

    Alpha cypermethrin was extracted from aqueous methanol solutions using hydrophobic organic solvents. The efficiency of extraction was shown to depend on the chemical nature of the solvent, the water to methanol ratio, and saturation of the aqueous methanol layer with an electrolyte. Optimal extraction of alpha-cypermethrin was achieved using toluene as the solvent under desalinization conditions. The extraction factor for the removal of the sought amount of alpha-cypermethrin from the water-methanol solution (4:1) using various solvents was calculated.

  20. Studies of float glass surfaces by neutron and x-ray reflection

    CERN Document Server

    Dalgliesh, R

    2001-01-01

    applicability of current off-specular scattering models. A rich surface structure has been found which results in reflection effects that cannot be explained by these models. Model systems have also been developed in an attempt to combine x-ray fluorescence techniques with reflectivity. The surface of glass and glass coatings have been studied using x-ray and neutron scattering techniques. In particular, the effect of aqueous solutions and humid atmospheres on both the fire polished and the tin rich side of float glass have been investigated using neutron and x-ray reflection. Isotopic substitution has enabled the number density of water molecules within the float glass surface to be monitored with respect to immersion time, temperature and impurity content. A thin gel-like water-rich layer of thickness approx 30A is observed at the surface accompanied by a more deeply penetrating layer which increases in depth with time reaching approx 500A after 6 months. The rate of water ingression is higher than predicte...

  1. Observing the in situ chiral modification of Ni nanoparticles using scanning transmission X-ray microspectroscopy

    Science.gov (United States)

    Watson, David J.; Acharya, Sushma; Nicklin, Richard E. J.; Held, Georg

    2014-11-01

    Enantioselective heterogeneous hydrogenation of Cdbnd O bonds is of great potential importance in the synthesis of chirally pure products for the pharmaceutical and fine chemical industries. One of the most widely studied examples of such a reaction is the hydrogenation of β-ketoesters and β-diketoesters over Ni-based catalysts in the presence of a chiral modifier. Here we use scanning transmission X-ray microscopy combined with near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS) to investigate the adsorption of the chiral modifier, namely (R,R)-tartaric acid, onto individual nickel nanoparticles. The C K-edge spectra strongly suggest that tartaric acid deposited onto the nanoparticle surfaces from aqueous solutions undergoes a keto-enol tautomerisation. Furthermore, we are able to interrogate the Ni L2,3-edge resonances of individual metal nanoparticles which, combined with X-ray diffraction (XRD) patterns showed them to consist of a pure nickel phase rather than the more thermodynamically stable bulk nickel oxide. Importantly, there appears to be no "particle size effect" on the adsorption mode of the tartaric acid in the particle size range ~ 90-~ 300 nm.

  2. Glasslike behavior in aqueous electrolyte solutions.

    Science.gov (United States)

    Turton, David A; Hunger, Johannes; Hefter, Glenn; Buchner, Richard; Wynne, Klaas

    2008-04-28

    When salts are added to water, generally the viscosity increases, suggesting that the ions increase the strength of the water's hydrogen-bond network. However, infrared pump-probe measurements on electrolyte solutions have found that ions have no influence on the rotational dynamics of water molecules, implying no enhancement or breakdown of the hydrogen-bond network. Here, we report optical Kerr effect and dielectric relaxation spectroscopic measurements, which have enabled us to separate the effects of rotational and transitional motions of the water molecules. These data show that electrolyte solutions behave like a supercooled liquid approaching a glass transition in which rotational and translational molecular motions are decoupled. It is now possible to understand previously conflicting viscosity data, nuclear magnetic resonance relaxation, and ultrafast infrared spectroscopy in a single unified picture.

  3. Glasslike Behavior in Aqueous Electrolyte Solutions

    CERN Document Server

    Turton, David A; Hefter, Glenn; Buchner, Richard; Wynne, Klaas; 10.1063/1.2906132

    2009-01-01

    When salts are added to water, the viscosity generally increases suggesting the ions increase the strength of the water's hydrogen-bond network. However, infrared pump-probe measurements on electrolyte solutions have found that ions have no influence on the rotational dynamics of water molecules implying no enhance-ment or breakdown of the hydrogen-bond network. Here we report optical Kerr-effect and dielectric relaxa-tion spectroscopic measurements, which have enabled us to separate the effects of rotational and transitional motions of the water molecules. These data show that electrolyte solutions behave like a supercooled liquid approaching a glass transition in which rotational and translational molecular motions are decoupled. It is now possible to understand previously conflicting viscosity data, nuclear magnetic resonance relaxation, and ultrafast infrared spectroscopy in a single unified picture.

  4. Quality control for X-ray dosimetry with Fricke dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Vivianne Lucia Bormann de [Centro Regional de Cincias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil)]. E-mail: lsouza@cnen.gov.br; Austerlitz, C. [East Carolina University, NC (United States)]. E-mail: camposc@ecu.edu

    2007-07-01

    It is a well-established fact that the success of radiation therapy is dependent on the accurate dosimetry of the radiation beam used. This dosimetry must include equipment performance as well. A system for Fricke dosimetry was used for this purpose. The Fricke solution and a parallel ionization chamber (used for comparison) were irradiated with an X-ray beam from a Pantak X-ray equipment. The ionization chamber was positioned at a distance of 500 mm of the focal point, in the central axis of the X-ray field which is defined as 100x100 mm{sup 2} at the calibration distance. A plexiglas phantom appropriate to hold the polypropylene tube was used to irradiate the vials with the Fricke solution. The irradiated solutions were transferred directly from the polypropylene vials to 10 mm length cuvettes and the optical densities were measured in 304 nm using a Beckman Counter Model DU 640 spectrophotometer. Three institutions were visited to verify their procedures and two were in accordance with the lAEA recommended procedures for soft X-ray dosimetry. The results of the measurements performed in the institutions visited show that the Fricke dosimeter system developed can be used for quality control for soft X-ray equipment. (author)

  5. LIGHT SCATTERING OF POLYSACCHARIDE FROM LACQUER IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lina; DU Yumin; KUMANOTANI JU

    1989-01-01

    The polysaccharide having weight-average molecular weight Mw= 1. 09 × 105 , isolated from the sap of lac trees ( Vietnam ), was separated into 12 fractions by aqueous-phase preparative gel permeation chromatography. The molecular weights and molecular weight distributions of the fractions were measured in aqueous 0.08M KCl/0.01 M NaAc and 0.4M KCl/0.05M NaAc at pH = 7.6 by light scattering, viscometry and gel permeation chromatography. The Mark-Houwink equation in aqueous 0.08M KCl/0.01M NaAc at30 ℃ was found to be [ η] = 2.28 ×10-2 M0.52w ( cm3/g ), which indicated the polysaccharide chain in the aqueous solution to be a spherical random coil.

  6. Comets: mechanisms of x-ray activity

    Science.gov (United States)

    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.

  7. X-Ray Visions of SS Cygni

    Science.gov (United States)

    Young, D. L.

    2004-12-01

    The Chandra X-Ray Observatory is the most sophisticated X-ray observatory launched by NASA. Chandra is designed to observe X-rays from highenergy regions of the universe, such as X-ray binary stars. On September 14, 2000, triggered by alerts from amateur astronomers worldwide, Chandra observed the outburst of the brightest northern dwarf nova SS Cygni. The cooperation of hundreds of amateur variable star astronomers and the Chandra X-Ray scientists and spacecraft specialists provided proof that the collaboration of amateur and professional astronomers is a powerful tool to study cosmic phenomena.

  8. X-rays from solar system objects

    CERN Document Server

    Bhardwaj, Anil; Gladstone, G Randall; Cravens, Thomas E; Lisse, Carey M; Dennerl, Konrad; Branduardi-Raymont, Graziella; Wargelin, Bradford J; Waite, J Hunter; Robertson, Ina; Ostgaard, Nikolai; Beiersdorfer, Peter; Snowden, Steven L; Kharchenko, Vasili; 10.1016/j.pss.2006.11.009

    2010-01-01

    During the last few years our knowledge about the X-ray emission from bodies within the solar system has significantly improved. Several new solar system objects are now known to shine in X-rays at energies below 2 keV. Apart from the Sun, the known X-ray emitters now include planets (Venus, Earth, Mars, Jupiter, and Saturn), planetary satellites (Moon, Io, Europa, and Ganymede), all active comets, the Io plasma torus (IPT), the rings of Saturn, the coronae (exospheres) of Earth and Mars, and the heliosphere. The advent of higher-resolution X-ray spectroscopy with the Chandra and XMM-Newton X-ray observatories has been of great benefit in advancing the field of planetary X-ray astronomy. Progress in modeling X-ray emission, laboratory studies of X-ray production, and theoretical calculations of cross-sections, have all contributed to our understanding of processes that produce X-rays from the solar system bodies. At Jupiter and Earth, both auroral and non-auroral disk X-ray emissions have been observed. X-ray...

  9. Transmission photoemission electron microscopy for lateral mapping of the X-ray absorption structure of a metalloprotein in a liquid cell.

    Science.gov (United States)

    Panzer, D; Beck, C; Maul, J; Möller, M; Decker, H; Schönhense, G

    2008-11-01

    We use photoemission electron microscopy in an X-ray transmission mode for full-field imaging of the X-ray absorption structure of copper in the respiratory metalloprotein hemocyanin KLH1. It contains 160 oxygen binding sites. Each site reversibly binds one molecule oxygen between two copper atoms. In our setup, hemocyanin is dissolved in aqueous solution and enclosed in an ultra-high vacuum compatible liquid sample cell with silicon nitride membranes. The local X-ray absorption structure of the liquid sample is converted into photoelectrons at the microscope side of the cell acting as a photocathode. In this way, different copper valencies are laterally distinguished under in vivo-like conditions, attributed to Cu(I) in the deoxy-state and Cu(II) in the oxy-state.

  10. Hydration and hydrolysis of thorium(IV) in aqueous solution and the structures of two crystalline thorium(IV) hydrates.

    Science.gov (United States)

    Torapava, Natallia; Persson, Ingmar; Eriksson, Lars; Lundberg, Daniel

    2009-12-21

    Solid octaaqua(kappa(2)O-perchlorato)thorium(IV) perchlorate hydrate, [Th(H(2)O)(8)(ClO(4))](ClO(4))(3).H(2)O, 1, and aquaoxonium hexaaquatris(kappaO-trifluoromethanesulfonato)thorium(IV) trisaquahexakis(kappaO-trifluoromethanesulfonato)thorinate(IV), H(5)O(2)[Th(H(2)O)(6)(OSO(2)CF(3))(3)][Th(H(2)O)(3)(OSO(2)CF(3))(6)], 2, were crystallized from concentrated perchloric and trifluoromethanesulfonic acid solutions, respectively. 1 adopts a severely distorted tricapped trigonal prismatic configuration with an additional oxygen from the perchlorate ion at a longer distance. 2 consists of individual hexaaquatris(kappaO-trifluoromethanesulfonato)thorium(IV) and trisaquahexakis(kappaO-trifluoromethanesulfonato)thorinate(IV) ions and an aquaoxonium ion bridging these two ions through hydrogen bonding. The hydrated thorium(IV) ion is nine-coordinated in aqueous solution as determined by extended X-ray absorption fine structure (EXAFS) and large angle X-ray scattering (LAXS). The LAXS studies also showed a second hydration sphere of about 18 water molecules, and traces of a 3rd hydration sphere. Structural studies in aqueous solution of the hydrolysis products of thorium(IV) have identified three different types of hydrolysis species: a mu(2)O-hydroxo dimer, [Th(2)(OH)(2)(H(2)O)(12)](6+), a mu(2)O-hydroxo tetramer, [Th(4)(OH)(8)(H(2)O)(16)](8+), and a mu(3)O-oxo hexamer, [Th(6)O(8)(H(2)O)(n)](8+). Detailed structures of these three hydrolysis species are given. A compilation of reported solid state structures of actinoid(IV) compounds with oxygen donor ligands show a strong correlation between the An-O bond distance and the coordination number. The earlier reported U-O bond distance in the hydrated uranium(IV) ion in aqueous solution, confirmed in this study, is related to nine-coordination. The hydrated tri- and tetravalent actinoid ions in aqueous solution all seem to be nine-coordinated. The trivalent ions show a significant difference in bond distance to prismatic and

  11. Photocatalytic degradation of molinate in aqueous solutions.

    Science.gov (United States)

    Bizani, E; Lambropoulou, D; Fytianos, K; Poulios, I

    2014-11-01

    In this study, the degradation of molinate through heterogeneous photocatalysis, using two different types of the semiconductor TiO2 as photocatalyst, as well as through homogeneous treatment, applying the photo-Fenton reaction, has been investigated. As far as heterogeneous photocatalysis is concerned, the degradation of the pesticide follows apparent first-order kinetics, while the type of the catalyst and the pH value of the solution affect the degradation rate. The effect of the addition of electron scavengers (H2O2 and K2S2O8) was also studied. In the case of photo-Fenton-assisted system, the degradation also follows pseudo-first-order kinetics. Parameters such as iron's and electron scavenger's concentration and inorganic ions strongly affect the degradation rate. The extent of pesticide mineralization was investigated using dissolved organic carbon (DOC) measurements. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fischeri. The detoxification and mineralization efficiency was found to be dependent on the system studied, and although it did not follow the rate of pesticide disappearance, it took place in considerable extent. The study of the photodegradation treatment was completed by the determination of the intermediate by-products formed during the process, which was carried out using LC-MS/MS technique and led to similar compounds with both processes.

  12. Photoelectron spectroscopy of aqueous solutions: streaming potentials of NaX (X = Cl, Br, and I) solutions and electron binding energies of liquid water and X-.

    Science.gov (United States)

    Kurahashi, Naoya; Karashima, Shutaro; Tang, Ying; Horio, Takuya; Abulimiti, Bumaliya; Suzuki, Yoshi-Ichi; Ogi, Yoshihiro; Oura, Masaki; Suzuki, Toshinori

    2014-05-07

    The streaming potentials of liquid beams of aqueous NaCl, NaBr, and NaI solutions are measured using soft X-ray, He(I), and laser multiphoton ionization photoelectron spectroscopy. Gaseous molecules are ionized in the vicinity of liquid beams and the photoelectron energy shifts are measured as a function of the distance between the ionization point and the liquid beam. The streaming potentials change their polarity with concentration of electrolytes, from which the singular points of concentration eliminating the streaming potentials are determined. The streaming currents measured in air also vanish at these concentrations. The electron binding energies of liquid water and I(-), Br(-), and Cl(-) anions are revisited and determined more accurately than in previous studies.

  13. Formation of Semimetallic Cobalt Telluride Nanotube Film via Anion Exchange Tellurization Strategy in Aqueous Solution for Electrocatalytic Applications.

    Science.gov (United States)

    Patil, Supriya A; Kim, Eun-Kyung; Shrestha, Nabeen K; Chang, Jinho; Lee, Joong Kee; Han, Sung-Hwan

    2015-11-25

    Metal telluride nanostructures have demonstrated several potential applications particularly in harvesting and storing green energy. Metal tellurides are synthesized by tellurization process performed basically at high temperature in reducing gas atmosphere, which makes the process expensive and complicated. The development of a facile and economical process for desirable metal telluride nanostructures without complicated manipulation is still a challenge. In an effort to develop an alternative strategy of tellurization, herein we report a thin film formation of self-standing cobalt telluride nanotubes on various conducting and nonconducting substrates using a simple binder-free synthetic strategy based on anion exchange transformation from a thin film of cobalt hydroxycarbonate nanostructures in aqueous solution at room temperature. The nanostructured films before and after ion exchange transformation reaction are characterized using field emission scanning electron microscope, energy dispersive X-ray analyzer, X-ray photoelectron spectroscopy, thin film X-ray diffraction technique, high resolution transmission electron microscope, and selected area electron diffraction analysis technique. After the ion exchange transformation of nanostructures, the film shows conversion from insulator to highly electrical conductive semimetallic characteristic. When used as a counter electrode in I3(-)/I(-) redox electrolyte based dye-sensitized solar cells, the telluride film exhibits an electrocatalytic reduction activity for I3(-) with a demonstration of solar-light to electrical power conversion efficiency of 8.10%, which is highly competitive to the efficiency of 8.20% exhibited by a benchmarked Pt-film counter electrode. On the other hand, the telluride film electrode also demonstrates electrocatalytic activity for oxygen evolution reaction from oxidation of water.

  14. Using Tunisian Phosphate Rock and Her Converted Hydroxyapatite for Lead Removal from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Hassen Bachoua

    2014-07-01

    Full Text Available Natural and synthesis apatites represent a cost effective soil amendment, which can be used for in situ reduction of lead bioavailability and mobility. In our previous work, we selected Tunisian Phosphate Rock (TPR and Hydroxyapatite (CaHAp as promising minerals for the removal of lead from aqueous solutions. X-ray powder diffraction patterns (DRX, Infra Red (IR, Thermogravimetric analysis (TGA and Scanning Electron Microscopy (SEM were used to characterize TPR and CaHAp. CaHAp was prepared from TPR and employed for the removal of Pb2+ ions at different concentrations from aqueous solution to determine the adsorption properties of CaHAp and compare them with those of a TPR. The kinetic data obtained indicated that the adsorption performances of the adsorbents depended both on their specific surface area and crystallinity. Complexation of lead ion on the adsorbent surface favoured the dissolution of hydroxyapatites characterized by a Ca/Pb molar ratio of 1.69. The maximum adsorption capacity of CaHAp for Pb2+ ions at 25 °C was 1.806 mmol /g relative to 1.035 mmol /g for TPR at the same temperature. The higher capacity of CaHAp was explained in terms of its porosity and crystallinity. The Pb2+ ions sorption results could be modelled by the Langmuir and Freundlich isotherms. The simulations of adsorption isotherms of Pb2+ on CaHAp allow us to conclude that there is a good correlation between the experimental data and the Langmuir model. On TPR, we show a good correlation between the experimental data and the Langmuir and Freundlich model.

  15. Exploration of As(III)/As(V) Uptake from Aqueous Solution by Synthesized Calcium Sulfate Whisker☆

    Institute of Scientific and Technical Information of China (English)

    Xiaojuan Chen; Liuchun Yang; Junfeng Zhang; Yan Huang

    2014-01-01

    Although common calcium-containing minerals such as calcite and gypsum may fix arsenic, the interaction be-tween modified calcic minerals and arsenic has seldom been reported. The uptake behavior of As(III)/As(V) from aqueous solutions by calcium sulfate whisker (CSW, dihydrate or anhydrite) synthesized through a cooling recrystal ization method was explored. A series of batch experiments were conducted to examine the effect of pH, reaction time, whisker dosage, and initial As concentration. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the samples prepared. The results showed that pH of the aqueous solution was an important parameter for As(III)/As(V) uptake, and an excellent removal efficiency could be achieved under strongly alkaline condition. The data from batch experiments for reaction of As(V) with calcium sulfate dihydrate whisker (CSDW) and calcium sulfate anhydrous whisker (CSAW) were well described with extended Langmuir EXT1 model, from which theoretic maximum adsorption capacity of 46.57 mg As(V)·(g CSDW)−1 and 39.18 mg As(V)·(g CSAW)−1 were obtained. Some calcium arsenate solids products, such as CaAsO3(OH) (weilite, syn), Ca3(AsO4)2 (calcium arsenate), CaO–As2O5, Ca–As–O, Ca5(AsO4)3OH·xH2O (calcium arsenate hydroxide hydrate), and CaH(AsO4)·2H2O (hydrogen calcium arsenic oxide hydrate), were detected at pH = 12.5 through XRD analysis. This indicates that the interaction mechanism between As(V) and CSW is a complex adsorption process combined with surface dissolution and chemical precipitation.

  16. Rapid dechlorination of chlorophenols in aqueous solution by [Ni|Cu] microcell

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Lifeng, E-mail: yinlifeng@gmail.com [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Dai, Yunrong, E-mail: daiyunrong@mail.bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Niu, Junfeng, E-mail: junfengn@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Bao, Yueping, E-mail: baoyueping@mail.bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Shen, Zhenyao, E-mail: zyshen@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China)

    2012-03-30

    Highlights: Black-Right-Pointing-Pointer Rapid dechlorination of chlorophenols in aqueous solution can be achieved by [Ni|Cu] mixture. Black-Right-Pointing-Pointer The decomposition rates of chlorophenols by [Ni|Cu] were decuple of that by [Fe|Ni], [Fe|Cu], [Zn|Cu], or [Sn|Cu]. Black-Right-Pointing-Pointer Ni{sup 0} acts as an indirect reductant and catalyst in dechlorination reaction. Black-Right-Pointing-Pointer The H* corridor mechanism from Ni to Cu is proposed based on hydrogen spillover. - Abstract: The [Ni|Cu] microcell was prepared by mixing the Ni{sup 0} and Cu{sup 0} particles. The composition and crystal form were characterized by X-ray diffraction (XRD) and scanning electron microscope. The results evidenced the zero-valence metals Ni and Cu were exposed on the surface of particles mixture. The [Ni|Cu] microcell was employed to decompose chlorophenols in aqueous solution by reductive dechlorination. The dechlorination rates of chlorophenols by [Ni|Cu] were >10 times faster than those by [Fe|Cu], [Zn|Cu], [Sn|Cu], and [Fe|Ni] mixtures under the same conditions. [Ni|Cu] is different from other zero valent metals (ZVMs) in that it performed the best at neutral pH. The main products of chlorophenol dechlorination were cyclohexanol and cyclohexanone. The reduction kinetics was between pseudo zero-order and first-order, depending on the pH, concentration, and temperature. These results, combined with electrochemical analysis, suggested that Ni{sup 0} acted as a reductant and catalyst in dechlorination reaction. The H* corridor mechanism from Ni{sup 0} to Cu{sup 0} was also proposed based on hydrogen spillover. The inhibition on the release of Ni{sup 2+} by adding natural organic matters and adjusting pH was investigated.

  17. Phosphorus removal from aqueous solution using iron coated natural and engineered sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Boujelben, N. [Laboratoire Eau Energie et Environnement, departement de genie geologique, Ecole Nationale d' Ingenieurs de Sfax, BP W 3038 Sfax (Tunisia)], E-mail: nesrine.boujelben@tunet.tn; Bouzid, J.; Elouear, Z. [Laboratoire Eau Energie et Environnement, departement de genie geologique, Ecole Nationale d' Ingenieurs de Sfax, BP W 3038 Sfax (Tunisia); Feki, M. [Unite de chimie industrielle I, Ecole Nationale d' Ingenieurs de Sfax, BP W 3038 Sfax (Tunisia); Jamoussi, F. [Laboratoire de Georessources CERTE BP 95, 2050 Hamam-Lif (Tunisia); Montiel, A. [Societe Anonyme de Gestion des Eaux de Paris, 9 rue Schoelcher, 75675 Paris Cedex 14 (France)

    2008-02-28

    New filtration materials covered with metallic oxides are good adsorbents for both cation and anion forms of pollutants. Sfax is one of the most important industrial towns in Tunisia. Its phosphate manufacture in particular is causing considerable amounts of water pollution. Therefore, there is a need to find out a new way of getting rid of this excessive phosphate from water. This work is aimed to examining the potential of three sorbent materials (synthetic iron oxide coated sand (SCS), naturally iron oxide coated sand (NCS) and iron oxide coated crushed brick (CB)) for removing phosphate ions from aqueous solutions. According to our literature survey CB was not used as adsorbent previously. Phosphate ions are used here as species model for the elimination of other similar pollutants (arsenates, antimonates). Optical microscope and scanning electron microscope (SEM) analyses were used to investigate the surface properties and morphology of the coated sorbents. Infra-red spectroscopy and X-ray diffraction techniques were also used to characterize the sorbent structures. Results showed that iron coated crushed brick possess more micro pores and a higher surface area owing to its clay nature. The comparative sorption of PO{sub 4}{sup 3-} from aqueous solutions by SCS, CB and NCS was investigated by batch experiments. The estimated optimum pH of phosphate ion retention for the considered sorbents was 5. The equilibrium data were analysed using the Langmuir and Freundlich isotherms. The sorption capacities of PO{sub 4}{sup 3-} at pH 5 were 1.5 mg/g for SCS, 1.8 mg/g for CB and 0.88 mg/g for NCS. The effect of temperature on sorption phenomenon was also investigated. The results indicated that adsorption is an endothermic process for phosphate ions removal. This study demonstrates that all the considered sorbents can be used as an alternative emerging technology for water treatment without any side effect or treatment process alteration.

  18. High-performance magnetic carbon materials in dye removal from aqueous solutions

    Science.gov (United States)

    Gao, Xiaoming; Zhang, Yu; Dai, Yuan; Fu, Feng

    2016-07-01

    To obtain a novel adsorbent with excellent adsorption capacity and convenient magnetic separation property, magnetic activated semi-coke was prepared by KOH activation method and further modified by FeCl3. The surface morphology, physical structure, chemical properties and textural characteristics of unmodified semi-coke, KOH-modified semi-coke and magnetic activated semi-coke were characterized by scanning electron microscopy, X-ray powder diffraction, N2 adsorption-desorption measurement, and electronic differential system. The adsorption characteristics of the magnetic activated semi-coke were explored for the removal of methyl orang (MO), methylene blue (MB), congo red (CR), acid fuchsin (AF), and rhodamine B (RB) from aqueous solution. The effects of adsorption parameters, including adsorbent dosage, pH and contact time, were investigated by comparing the adsorption properties of the magnetic activated semi-coke to RB. The result showed that the magnetic activated semi-coke displayed excellent dispersion, convenient separation and high adsorption capacity. The adsorption experiment data indicated that the pseudosecond order model and the Langmuir model could well explain the adsorption processes of RB on the magnetic activated semi-coke, and the maximum adsorption capacity (qm) was 526.32 mg/g. The values of thermodynamic parameters (ΔG°, ΔH° and ΔS°) indicated that the adsorption process depended on the temperature of the aqueous phase, and it was spontaneous and exothermic in nature. As the addition of the magnetic activated semi-coke, the color of the solution significantly faded. Subsequently, fast aggregation of the magnetic activated semi-coke from their homogeneous dispersion in the presence of an external magnetic field could be happened. So, the magnetic activated semi-coke displayed excellent dispersion, convenient separation and high adsorption capacity.

  19. Permeability in a state of partial solidification of aqueous solution

    Science.gov (United States)

    Okada, Masashi; Kang, Chaedong; Okiyama, Haruhiko

    A mushy region was formed by solidifying NaCl aqueous solution in a circular tube or a rectangular tube. The measurements of permeability were performed by changing volume fraction of liquid region in the mushy region. The dendritic ice in the solidification process was observed with a CCD microscope. The following results were obtained. The permeability increases with the volume fraction of liquid phase, and decreases with increasing the super-cooling degree of the solution or increasing the initial concentration of the solution, and is constant after the mushy region was formed. The arm space of dendrite becomes narrower as the super-cooling degree of the solution increases.

  20. Radiolysis of paracetamol in dilute aqueous solution

    Science.gov (United States)

    Szabó, László; Tóth, Tünde; Homlok, Renáta; Takács, Erzsébet; Wojnárovits, László

    2012-09-01

    Using radiolytic experiments hydroxyl radical (main reactant in advanced oxidation processes) was shown to effectively destroy paracetamol molecules. The basic reaction is attachment to the ring. The hydroxy-cyclohexadienyl radical produced in the further reactions may transform to hydroxylated paracetamol derivatives or to quinone type molecules and acetamide. The initial efficiency of aromatic ring destruction in the absence of dissolved O2 is c.a. 10%. The efficiency is 2-3 times higher in the presence of O2 due to its reaction with intermediate hydroxy-cyclohexadienyl radical and the subsequent ring destruction reactions through peroxi radical. Upon irradiation the toxicity of solutions at low doses increases with the dose and then at higher doses it decreases. This is due to formation of compounds with higher toxicity than paracetamol (e.g. acetamide, hidroquinone). These products, however, are highly sensitive to irradiation and degrade easily.

  1. Full-field transmission x-ray imaging with confocal polycapillary x-ray optics.

    Science.gov (United States)

    Sun, Tianxi; Macdonald, C A

    2013-02-07

    A transmission x-ray imaging setup based on a confocal combination of a polycapillary focusing x-ray optic followed by a polycapillary collimating x-ray optic was designed and demonstrated to have good resolution, better than the unmagnified pixel size and unlimited by the x-ray tube spot size. This imaging setup has potential application in x-ray imaging for small samples, for example, for histology specimens.

  2. Reactive Extraction of Alcohols from Apolar Hydrocarbons with Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The aqueous solutions are evaluated as sustainable reactive extraction solvents for the recovery of monohydroxyl alcohols (benzyl alcohol, 1-hexanol, cyclohexanol) present in few-percent concentrations in apolar hydrocarbons (toluene, n-hexane, and cyclohexane) by considering two approaches. An aqueous solution containing a reactive extractant, like borate salts, borate complexes, a monosalt of dicarboxylic acid,hydroxypropyl-cyclodextrins, and silver nitrate, shows limited potential to be used. Another approach, in which the alcohol is chemically modified prior to the extraction into an easy-extractable form, in this case a monoesterlcarboxylic acid, shows much more potential. An environmentally benign aqueous solution of sodium hydrogen carbonate can provide a distribution ratio of benzyl alcohol up to 200, leaving the solubility of the organic solvent in the aqueous solution unchanged relative to pure water and therefore increasing the selectivity with two orders of magnitude. The modification of aromatic, cyclo-aliphatic, and linear aliphatic alcohols can be performed efficiently in the apolar organic solvent without need for a catalyst. The recovery of the modified alcohol can be performed by back-extraction in combination with a spontaneous hydrolysis.

  3. Reactive Extraction of Alcohols from Apolar Hydrocarbons with Aqueous Solutions

    NARCIS (Netherlands)

    Kuzmanovic, Boris; Kuipers, Norbert J.M.; Haan, de André B.; Kwant, Gerard

    2006-01-01

    The aqueous solutions are evaluated as sustainable reactive extraction solvents for the recovery of monohydroxyl alcohols (benzyl alcohol, 1-hexanol, cyclohexanol) present in few-percent concentrations in apolar hydrocarbons (toluene, n-hexane, and cyclohexane) by considering two approaches. An aque

  4. Solubility of carbon dioxide in aqueous piperazine solutions

    NARCIS (Netherlands)

    Derks, P. W. J.; Dijkstra, H. B. S.; Hogendoorn, J. A.; Versteeg, G. F.

    2005-01-01

    In the present work, new experimental data are presented on the solubility of carbon dioxide in aqueous piperazine solutions, for concentrations of 0.2 and 0.6 molar piperazine and temperatures of 25, 40, and 70°C respectively. The present data, and other data available in the literature, were corr

  5. Rheological properties of silica suspensions in aqueous cellulose derivatives solutions

    Science.gov (United States)

    Ryo, Y.; Kawaguchi, M.

    1992-05-01

    The rheological properties of the silica suspensions in aqueous solutions of hydroxypropylmethylcellulose (HPMC) were investigated in terms of the shear stress and storage and loss moduli (G' and G`) as a function of silica content, HPMC concentration, and HPMC molecular weight by using a coaxial cylinder rheometer.

  6. Oscillometric and conductometric analysis of aqueous and organic dosimeter solutions

    DEFF Research Database (Denmark)

    Kovacs, A.; Slezsak, I.; McLaughlin, W.L.;

    1995-01-01

    ''conductometric'' electrodes and the study of the effect of frequency on the sensitivity of the method. On the basis of these investigations an oscillometric reader has been designed and tested. The same evaluation methods have been tested on the irradiated aqueous alanine solutions, aiming also at the study...

  7. Adsorptive removal of antibiotics from aqueous solution using carbon materials.

    Science.gov (United States)

    Yu, Fei; Li, Yong; Han, Sheng; Ma, Jie

    2016-06-01

    Antibiotics, an important type of environmental contamination, have attracted many researchers to the study of their removal from aqueous solutions. Adsorption technology is a fast, efficient, and economical physicochemical method that is extensively used in wastewater treatment. From original activated carbon and carbon nanotubes to the latest graphene-based materials, carbon-based materials have been widely used as highly effective adsorbents for contaminant removal from aqueous solution because of their large specific surface area, high porosity, and high reaction activity. In this article, adsorption removal methods for four major types of antibiotic (tetracyclines, sulfonamides, macrolides, and quinolones) are reviewed. We also provide an overview of the application development of carbon materials as adsorbents for antibiotic removal from aqueous solution. The most promising works are discussed, and the main challenges in preparing high-performance adsorbents and the development tendency of adsorbents are also analyzed. This work provides theoretical guidance for subsequent research in the design and modification of carbon materials for applications in the adsorption removal of antibiotics from aqueous solution.

  8. CATALYSIS BY SURFACTANT AGGREGATES IN AQUEOUS-SOLUTIONS

    NARCIS (Netherlands)

    ENGBERTS, JBFN

    1992-01-01

    Catalysis of organic reactions by unfunctionalized surfactant aggregates (micelles, vesicles) in aqueous solution is largely determined by medium effects induced at the micellar binding sites and by entropy effects due to compartimentalization. The efficiency of these catalytic effects responds to c

  9. Kinetics of absorption of carbon dioxide in aqueous piperazine solutions

    NARCIS (Netherlands)

    Derks, P. W. J.; Kleingeld, T.; van Aken, C.; Hogendoorn, J. A.; Versteeg, G. F.

    2006-01-01

    In the present work the absorption of carbon dioxide into aqueous piperazine (PZ) solutions has been studied in a stirred cell, at low to moderate temperatures, piperazine concentrations ranging from 0.6 to 1.5 kmol m- 3, and carbon dioxide pressures up to 500 mbar, respectively. The obtained experi

  10. DETERMINATION OF CHLORHEXIDINE IN SALIVA AND IN AQUEOUS-SOLUTIONS

    NARCIS (Netherlands)

    de Vries, J.; Ruben, J; Arends, J.

    1991-01-01

    A new method is presented for the determination of chlorhexidine in centrifuged saliva and in aqueous solutions by means of fluorescence spectroscopy. The method relies on complex formation between chlorhexidine and eosin. The fluorescence value of the chlorhexidine-eosin system decreases with incre

  11. Colorimetric and fluorescent detection of biological thiols in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    Yin-Hui Li; Jin-Feng Yang; Chang-Hui Liu; Ji-Shan Li; Rong-Hua Yang

    2013-01-01

    A new colorimetric and fluorescent probe,2-(2,4-dinitrostyryl)-1,3,3-trimethyl-3H-indolium iodide (DTI),for selective and sensitive detection of biological thiols is reported.In aqueous solution at physiological pH 7.4,biological thiols react with DTI via Michael addition to give the brownish red adduct concomitant with fluorescence emission decrease.

  12. Adsorption of lead ions from aqueous solutions using clinoptilolite

    OpenAIRE

    Golomeova, Mirjana; Zendelska, Afrodita; Krstev, Boris; Golomeov, Blagoj; Blažev, Krsto; Krstev, Aleksandar

    2014-01-01

    The adsorption of lead ions from synthetic aqueous solutions was performed by using natural zeolite (clinoptilolite). In order to determine the effectivity of clinoptilolite a series of experiments were performed under batch conditions from single ion solutions. Experiments were carried out at different initial concentration of lead ions, different initial pH values and different adsorbent mass. The adsorption kinetics is reasonably fast. It means that in the first 20 min approximately 90...

  13. Removal of azo dye from aqueous solutions using chitosan

    Directory of Open Access Journals (Sweden)

    Zuhair Jabbar

    2014-06-01

    Full Text Available Adsorption of Congo Red (CR from aqueous solution onto chitosan was investigated in a batch system. The effects of solution pH, initial dye concentration, and temperature were studied. Results indicated that chitosan could be used as a biosorbent to remove the azo dyes from contaminated water. Synthesize of chitosan involved three main stages as preconditioning, demineralization, deproteinization and deacetylation. Chitosan was characterized using Fourier Transform Infrared Spectroscopy (FTIR and solubility in 1% acetic acid.

  14. Biosorption Performance of Biodegradable Polymer Powders for the Removal of Gallium(III ions from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Lee Ching-Hwa

    2015-09-01

    Full Text Available Gallium (Ga is considered an important element in the semiconducting industry and as the lifespan of electronic products decrease annually Ga-containing effluent has been increasing. The present study investigated the use of biodegradable polymer powders, crab shell and chitosan, in the removal of Ga(III ions from aqueous solution. Ga(III biosorption was modeled to Lagergren-first, pseudo-second order and the Weber-Morris models. Equilibrium data was modeled to the Langmuir, Freundlich and Langmuir-Freundlich adsorption isotherms to determine the probable biosorption behavior of Ga(III with the biosorbents. The biosorbents were investigated by Fourier Transform Infrared Spectroscopy, X-ray Diffraction and Scanning Electron Microscopy/Energy Dispersive Spectra analysis.

  15. Synthesis of DNPH/SDS/Fe3O4 Nanoparticles for Removal of Cr (VI Ions From Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Soheil Sobhanardakani

    2016-06-01

    Full Text Available In this study, sodium dodecyl sulfate (SDS coated magnetite modified with 2, 4-Dinitrophenylhydrazine was used to remove Cr (VI ions from aqueous solution. The modified magnetite nanoparticles were characterized by X-ray diffraction (XRD analysis, Fourier transform infrared spectroscopy (FT-IR, scanning electron microscopy (SEM, and SEM–EDXS measurement. The synthesized nanoparticles exhibited a high surface area of 75.5 m2 g−1 and were of 20 - 35 nm in particle size. The effects of parameters, including pH, dose of adsorbent, temperature and contact time were investigated to find the optimum adsorption conditions. Adsorption data fits well with the Langmuir isotherm model with a maximum adsorption capacity (qm and a Langmuir adsorption equilibrium constant (b of 169.5 mg g-1 and 0.168 L mg-1, respectively. The adsorption kinetic agrees well with pseudo-second-order model.

  16. Coumarin-based 'turn-off' fluorescent chemosensor with high selectivity for Cu2+ in aqueous solution

    Science.gov (United States)

    Xu, Wen-Jun; Qi, De-Qiang; You, Jin-Zong; Hu, Fei-Fei; Bian, Jia-Ying; Yang, Chun-Xia; Huang, Juan

    2015-07-01

    Coumarin-based "turn-off" fluorescent chemosensor, 3-acetoacetyl-7-diethylaminocoumarin (1), has been synthesized and structurally characterized by IR, 1H NMR and X-ray crystal structure analysis. The fluorescence behaviors in the presence of various metal ions were investigated in aqueous media. 1 Exhibits highly selective and sensitive absorbance and fluorescence sensing ability for Cu2+ over other metal ions. Addition of Cu2+ to the aqueous solution of 1 gave rise to obvious absorbance change and fluorescence quenching. Other competing ions, such as Mg2+, Ba2+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, Pb2+, Cd2+, Hg2+, induced negligible absorbance and fluorescence changes under the same conditions. The job's plot showed that the stoichiometry between 1 and Cu2+ was estimated to be 1:1. The fluorescence intensity varied almost linearly vs. the concentration of Cu2+ (1.0-7.0 μM), and the detection limit of Cu2+ was estimated to be 1.81 nM, indicating that 1 can be used as "turn-off" fluorescent chemosensor to selectively detect Cu2+ in aqueous solution.

  17. A new technique for the deposition of standard solutions in total reflection X-ray fluorescence spectrometry (TXRF) using pico-droplets generated by inkjet printers and its applicability for aerosol analysis with SR-TXRF

    Energy Technology Data Exchange (ETDEWEB)

    Fittschen, U.E.A. [University of Hamburg, Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany)]. E-mail: ursula.fittschen@chemie.uni-hamburg.de; Hauschild, S. [University of Hamburg, Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Amberger, M.A. [University of Hamburg, Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Lammel, G. [Max Planck Institute for Meteorology, Bundesstrasse 53, 20146 Hamburg (Germany); Streli, C. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Vienna (Austria); Foerster, S. [University of Hamburg, Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Wobrauschek, P. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Vienna (Austria); Jokubonis, C. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Vienna (Austria); Pepponi, G. [ITC-irst, Via Sommarive 18, 38050 Povo (Trento) (Italy); Falkenberg, G. [Hamburger Synchrotronstrahlungslabor at Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany); Broekaert, J.A.C. [University of Hamburg, Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany)

    2006-11-15

    A new technique for the deposition of standard solutions on particulate aerosol samples using pico-droplets for elemental determinations with total reflection X-ray fluorescence spectrometry (TXRF) is described. It enables short analysis times without influencing the sample structure and avoids time consuming scanning of the sample with the exciting beam in SR-TXRF analysis. Droplets of picoliter volume ({approx} 5-130 pL) were generated with commercially available and slightly modified inkjet printers operated with popular image processing software. The size of the dried droplets on surfaces of different polarity namely silicone coated and untreated quartz reflectors, was determined for five different printer types and ten different cartridge types. The results show that droplets generated by inkjet printers are between 50 and 200 {mu}m in diameter (corresponding to volumes of 5 to 130 pL) depending on the cartridge type, which is smaller than the width of the synchrotron beam used in the experiments (< 1 mm at an energy of 17 keV at the beamline L at HASYLAB, Hamburg). The precision of the printing of a certain amount of a single element standard solution was found to be comparable to aliquoting with micropipettes in TXRF, where for 2.5 ng of cobalt relative standard deviations of 12% are found. However, it could be shown that the printing of simple patterns is possible, which is important when structured samples have to be analysed.

  18. Growth and Structure of Zirconium Hydrous Polymers in Aqueous Solutions

    Science.gov (United States)

    Singhal; Toth; Beaucage; Lin; Peterson

    1997-10-15

    Zirconium oxychloride solutions prepared at different pH were heated at elevated temperatures for various aging periods to gain an understanding of the growth mechanism and structure of zirconium hydrous polymers. Small angle X-ray scattering (SAXS) measurements were made on these solutions. It was observed that shape of clusters at the earlier stages of growth is close to a rod rather than a sheet as suggested earlier. The scattering data indicate that a rod-shaped primary particle is formed at pH 1.2, and on an increase in the pH, the primary particles become more branched. On aging more than 1250 min at 92°C, these primary particles form large aggregates while retaining the primary particle structure. These aggregates, which are mass fractal in nature, restructure while growing in size and eventually transform into dense particles. Scattering data in this study were not enough to determine a specific kinetic growth model of the aggregates because the scattering intensity at low q constantly changes with time during the restructuring process. Copyright 1997 Academic Press. Copyright 1997Academic Press

  19. Growth and structure of zirconium hydrous polymers in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Singhal, A. [Oak Ridge National Lab., TN (United States)]|[Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Toth, L.M.; Lin, J.S. [Oak Ridge National Lab., TN (United States); Beaucage, G. [Univ. of Cincinnati, OH (United States). Dept. of Materials Science and Engineering; Peterson, J. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry

    1997-10-15

    Zirconium oxychloride solutions prepared at different pH were heated at elevated temperatures for various aging periods to gain an understanding of the growth mechanism and structure of zirconium hydrous polymers. Small angle X-ray scattering (SAXS) measurements were made on these solutions. It was observed that shape of clusters at the earlier stages of growth is close to a rod rather than a sheet as suggested earlier. The scattering data indicate that a rod-shaped primary particle is formed at pH 1.2, and on an increase in the pH, the primary particles become more branched. On aging more than 1,250 min at 92 C, these primary particles form large aggregates while retaining the primary particle structure. These aggregates, which are mass fractal in nature, restructure while growing in size and eventually transform into dense particles. Scattering data in this study were not enough to determine a specific kinetic growth model of the aggregates because the scattering intensity at low q constantly changes with time during the restructuring process.

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

    Directory of Open Access Journals (Sweden)

    Michał Taube

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

  1. Phytoremediation of Heavy Metals in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Felix Aibuedefe AISIEN

    2010-12-01

    Full Text Available One of the major environmental problems is the pollution of water and soil by toxic heavy metals. This study investigated the phytoremediation potential of water hyacinth, for the removal of cadmium (Cd, lead (Pb and zinc (Zn. Water hyacinths were cultured in bore-hole water, supplemented with 5mg/l of Zn and Pb and 1mg/l of Cd at pH 4.5, 6.8 and 8.5. The plants were separately harvested each week for six weeks. The results showed that removal of these metals from solution was fast especially in the first two weeks, after which it became gradual till saturation point was reached. The accumulation of Cd and Zn in leaves and roots increased with increase in pH. The highest accumulation was in the roots with metal concentration of 4870mg/kg, 4150mg/kg and 710mg/kg for Zn, Pb and Cd respectively at pH 8.5. The maximum values of bioconcentration factor (BCF for Zn, Pb and Cd were 1674, 1531 and 1479 respectively, suggesting that water hyacinth was good accumulator of Zn, Pb and Cd, and could be used to treat industrial wastewater contaminated with heavy metals such as Zn, Pb and Cd.

  2. Block copolymer membranes for aqueous solution applications

    KAUST Repository

    Nunes, Suzana Pereira

    2016-03-22

    Block copolymers are known for their intricate morphology. We review the state of the art of block copolymer membranes and discuss perspectives in this field. The main focus is on pore morphology tuning with a short introduction on non-porous membranes. The two main strategies for pore formation in block copolymer membranes are (i) film casting and selective block sacrifice and (ii) self-assembly and non-solvent induced phase separation (SNIPS). Different fundamental aspects involved in the manufacture of block copolymer membranes are considered, including factors affecting the equilibrium morphology in solid films, self-assembly of copolymer in solutions and macrophase separation by solvent-non-solvent exchange. Different mechanisms are proposed for different depths of the SNIPS membrane. Block copolymer membranes can be prepared with much narrower pore size distribution than homopolymer membranes. Open questions and indications of what we consider the next development steps are finally discussed. They include the synthesis and application of new copolymers and specific functionalization, adding characteristics to respond to stimuli and chemical environment, polymerization-induced phase separation, and the manufacture of organic-inorganic hybrids.

  3. Removal of Co(II) from aqueous solutions by sulfonated magnetic multi-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Juanjuan; Dong, Yunhui; Li, Jun; Min, Fanlian; Li, Yueyun [Shandong University of Technology, Zibo (China); Liu, Zhengjie [Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei, Anhui (China)

    2015-11-15

    Sulfonated magnetic multi-walled carbon nanotubes (SMMWCNTs) were applied in the sorption of Co(II) from aqueous solutions. The SMMWCNTs were prepared and characterized by scanning electron microscope (SEM), Fourier transform infrared (FTIR), and X-ray diffractometer (XRD) test. A large number of influencing factors to the sorption process were investigated, such as pH, ionic strength, contact time, cations, anions, humic acid (HA), fulvic acid (FA) and temperature. The results indicated that the Co(II) sorption was strongly controlled by the pH and ionic strength. Moreover, foreign anions, such as F−, Cl{sup -} and Br{sup -}, had an obvious effect on the sorption process, which depended on the electronegativity of the anions. On the other hand, cations restrained sorption strongly, such as Mg{sup 2+} and Ca{sup 2+}. The existence of HA/FA enhanced sorption process at pH<8 while weakened at pH>8. As revealed by the sorption results, the Langmuir adsorption model was more favorable than the Freundlich adsorption model, and the pseudo-second-order model could fit the data much better than the pseudo-first-order. The thermodynamic analysis suggested that sorption was spontaneous and endothermic. What's more, the stability experiments of the SMMWCNTs showed that SMMWCNTs could maintain excellent magnetic stability and dispersion stability. Thus, this SMMWCNTs sorben was believed to be a promising material for the selective removal of Co(II) from heavy metal-containing wastewater.

  4. Adsorption Behavior of Ferromagnetic Carbon Nanotubes for Methyl Orange from Aqueous Solution.

    Science.gov (United States)

    Wang, Liping; Zhang, Mingyu; Zhao, Chenxi; Yang, Shan

    2016-03-01

    The ferromagnetic carbon nanotubes which can be easily separated from aqueous solution were prepared and characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Batch experiments were carried out to investigate the adsorption behavior of ferromagnetic carbon nanotubes for removing methyl orange (MO). The results showed that these ferromagnetic carbon nanotubes were richer in surface function groups than the carbon nanotubes did, furthermore, both γ-Fe2O3 and Fe with ferromagnetism were found on the surface of carbon nanotubes. The results also demonstrated that ferromagnetic carbon nanotubes possessed stronger adsorption ability for MO than carbon nanotubes did. The adsorption isotherms followed Langmuir isotherm equation and the adsorption kinetics could be well described with the pseudo second-order kinetic model. The adsorption process involved an intraparticle diffusion, while it was not the only rate-controlling step. The values of AG were negative and the value of ΔH is -12.37 kJ/mol, proving that the adsorption of MO onto ferromagnetic carbon nanotubes was a spontaneous and exothermic process.

  5. Adsorption of Methylene Blue from Aqueous Solution onto Hydrochloric Acid-modified Rectorite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Gaoke; LIU Guanfeng; GUO Yadan

    2011-01-01

    H+-rectorite clay,which was prepared by modifying the raw rectorite with 10% hydrochloric acid at 60 ℃C for 24 h,was used as an absorbent for removal of methyl blue (MB) from aqueous solutions.The morphology and the structure and crystallinity of the pristine rectorite and the H+-rectorite were characterized by scanning electron microscopy (SEM) technique and X-ray diffraction (XRD) technique,respectively.The results showed that the H+-rectorite exhibited high adsorption ability than the raw rectorite,and it was found that the removal percentage of MB increased with increasing in adsorbents dose,whereas the adsorption amount q,(mg/g) decreased.The equilibrium was attained within 30 min in adsorption process,and the maximum adsorption capacity of H+-rectorite for methylene blue reached as high as 37 mg/g.Besides,the effect of temperature on the adsorption of MB with H+-rectorite was investigated and the equilibrium data were well fitted to Freundlich equations.The H+-rectorite absorbent saturated with MB can be regenerated by calcinating at 400 ℃ for 2 h and the regenerated absorbent still showed higher percentage removal of MB.

  6. Adsorption of Lead Ions from Aqueous Solutions Using Gamma Irradiated Minerals

    Directory of Open Access Journals (Sweden)

    Julián Cruz-Olivares

    2016-01-01

    Full Text Available For the first time, an irradiated mineral was used as a novel modified adsorbent for lead removal of aqueous solutions. The effects of gamma radiation doses and temperature on the lead adsorption capacity of an unknown mineral were evaluated. The results show that, in the chemisorption process, the highest adsorption capacity (9.91 mg/g and the maximum percentage of lead removal (99.1% were reached at 40°C when using an irradiated mineral at 150 kGy. The improvement on the lead adsorption speed was the most important feature of the irradiated mineral. The experimental results were successfully correlated with the pseudo second-order kinetic model. For all results, the average absolute relative deviations (AARD were less than 13.20%, and the correlation factor (r2 was higher than 0.998. Moreover, the average values of the thermodynamic parameters (ΔG0=-10612 J/mol, ΔH0=-12360 J/mol, and ΔS0=171 J/mol K suggest the feasibility of the proposed process, in terms of the endothermic and irreversible chemisorption results; moreover, ion exchange was evaluated through the EDS results. The X-ray diffraction analysis showed that the unknown irradiated mineral is mainly composed of quartz (SiO2, calcite (CaCO3, and calcium magnesium silicate (Ca0.15Mg0.85 Mg (SiO6.

  7. Photoelectrocatalytic Degradation of Organic Pollutants in Aqueous Solution Using a Pt-TiO2 Film

    Directory of Open Access Journals (Sweden)

    Chun He

    2009-01-01

    Full Text Available A series of Pt-TiO2 films with nanocrystaline structure was prepared by a procedure of photodeposition and subsequent dip-coating. The Pt-TiO2 films were characterized by X-ray diffraction, scanning electronic microscope, electrochemical characterization to examine the surface structure, chemical composition, and the photoelectrochemical properties. The photocatalytic activity of the Pt-TiO2 films was evaluated in the photocatalytic (PC and photoelectrocatalytic (PEC degradation of formic acid in aqueous solution. Compared with a TiO2 film, the efficiency of formic acid degradation using the Pt-TiO2 films was significantly higher in both the PC and PEC processes. The enhancement is attributed to the action of Pt deposits on the TiO2 surface, which play a key role by attracting conduction band photoelectrons. In the PEC process, the anodic bias externally applied on the illuminated Pt-TiO2 films can further drive away the accumulated photoelectrons from the metal deposits and promote a process of interfacial charge transfer.

  8. Removal of Pb(II) from aqueous solution using modified and unmodified kaolinite clay.

    Science.gov (United States)

    Jiang, Ming-qin; Wang, Qing-ping; Jin, Xiao-ying; Chen, Zu-liang

    2009-10-15

    Modified kaolinite clay with 25% (w/w) aluminium sulphate and unmodified kaolin were investigated as adsorbents to remove Pb(II) from aqueous solution. The results show that amount of Pb(II) adsorbed onto modified kaolin (20mg/g) was more than 4.5-fold than that adsorbed onto unmodified kaolin (4.2mg/g) under the optimized condition. In addition, the linear Langmuir and Freundlich models were used to describe equilibrium isotherm. It is observed that the data from both adsorbents fitted well to the Langmuir isotherm. The kinetic adsorption of modified and unmodified kaolinite clay fitted well to the pseudo-second-order model. Furthermore, both modified and unmodified kaolinite clay were characterized by X-ray diffraction, Fourier transform infrared (FT-IR) and scanning electron microscope (SEM). Finally, both modified and unmodified kaolinite clay were used to remove metal ions from real wastewater, and results show that higher amount of Pb(II) (the concentration reduced from 178 to 27.5mg/L) and other metal ions were removed by modified kaolinite clay compared with using unmodified adsorbent (the concentration reduced from 178 to 168 mg/L).

  9. Magnetic carboxylated cellulose nanocrystals as adsorbent for the removal of Pb(II) from aqueous solution.

    Science.gov (United States)

    Lu, Jiao; Jin, Ru-Na; Liu, Chao; Wang, Yan-Fei; Ouyang, Xiao-Kun

    2016-12-01

    A novel magnetic carboxylated cellulose nanocrystal composite (CCN-Fe3O4) was prepared as an adsorbent for the adsorption of Pb(II) from aqueous solution. The new adsorbent was characterized by transmission electron microscopy, vibrating sample magnetometry, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Batch experiments were carried out to investigate the effects of contact time, adsorbent dose, pH, and temperature on adsorption capacity. Pb(II) adsorption onto CCN-Fe3O4 reached equilibrium in 240min, and the maximum adsorption capacity of Pb(II) was 63.78mgg(-1) at 298.2K. The equilibrium data fitted the Langmuir isotherm model better than the Freundlich isotherm model, and they were well explained in terms of pseudo-second-order kinetics. Thermodynamics studies indicated that the adsorption of Pb(II) onto CCN-Fe3O4 was spontaneous and endothermic in nature. The adsorbent could also be regenerated with acid treatment and successfully reapplied.

  10. Mechanisms of phosphate removal from aqueous solution by blast furnace slag and steel furnace slag

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We report the adsorption of phosphate and discuss the mechanisms of phosphate removal from aqueous solution by burst furnace slag (BFS) and steel furnace slag (SFS). The results show that the adsorption of phosphate on the slag was rapid and the majority of adsorption was completed in 5~10 min. The adsorption capacity of phosphate by the slag was reduced dramatically by acid treatment. The relative contribution of adsorption to the total removal of phosphate was 26%~28%. Phosphate adsorption on BFS and SFS follows the Freundlich isotherm, with the related constants ofk 6.372 and 1/n 1.739 for BFS, and ofk 1.705 and 1/n 1.718 for SFS. The pH and Ca2+ concentration were decreased with the addition of phosphate, suggesting the formation of calcium phosphate precipitation. At pH 2.93 and 6.93, phosphate was desorbed by about 36%~43% and 9%~11%, respectively.These results indicate that the P adsorption on the slag is not completely reversible and that the bond between the slag particles and adsorbed phosphate is strong. The X-ray diffraction (XRD) patterns of BFS and SFS before and after phosphate adsorption verify SFS is related to the formation of phosphate calcium precipitation and the adsorption on hydroxylated oxides. The results show that BFS and SFS removed phosphate nearly 100%, indicating they are promising adsorbents for the phosphate removal in wastewater treatment and pollution control.

  11. Application of modified bentonite using sulfuric acid for the removal of hexavalent chromium from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Masoud Moradi

    2015-09-01

    Full Text Available Background: Environmental contamination by chromium (Cr has become an important issue due to its adverse effects on human health and environment. This study was done to evaluate the application of modified bentonite using sulfuric acid as an adsorbent in the removal of hexavalent Cr from aqueous solution. Methods: Adsorbent features were determined using x-ray diffraction (XRD, fourier transformed infrared spectroscopy (FTIR and scanning electron microscope (SEM techniques. Thereafter, the effect of pH, contact time, adsorbent dosage and different concentrations of Cr was investigated. The experimental data was fitness in terms of kinetic and equilibrium adsorption processes. Results: The maximum capacity (Qm of Cr(VI according to Langmuir model was obtained at 4.21 mg/g. The experimental data properly obeyed the Longmuir and pseudo-second-order models. The highest percentage of Cr(VI adsorption was observed at pH = 3 and the process after 60 minutes reached the equilibrium state. Conclusion: In Langmuir expression, the dimensionless constant separation term (RL values for the adsorption of Cr onto the modified bentonite was in the range of 0-1, indicating that the adsorption is a favorable process and the modified bentonite has good potential in removing hexavalent Cr using sulfuric acid.

  12. Interfacial behavior of perchlorate versus chloride ions in saturated aqueous salt solutions

    Energy Technology Data Exchange (ETDEWEB)

    Ghosal, S; Kuo, I W; Baer, M D; Bluhm, H

    2009-04-14

    In recent years combination of theoretical and experimental work have presented a novel view of the aqueous interface wherein hard and/or multiply charged ions are excluded from the interface, but large polarizable anions show interfacial enhancement relative to the bulk. The observed trend in the propensity of anions to adsorb at the air/water interface appears to be reverse of the Hofmeister series for anions. This study focuses on experimental and theoretical examination of the partitioning behavior of perchlorate (ClO{sub 4}{sup -}) and chloride (Cl{sup -}) ions at the air/water interface. We have used ambient pressure X-ray photoelectron spectroscopy technique to directly probe the interfacial concentrations of ClO{sub 4}{sup -} and Cl{sup -} ions in sodium perchlorate and sodium chloride solutions, respectively. Experimental observations are compared with first principles molecular dynamics simulations. Both experimental and simulation results show enhancement of ClO{sub 4}{sup -} ion at the interface, compared with the absence of such enhancement in the case of Cl{sup -} ion. These observations are in agreement with the expected trend in the interfacial propensity of anions based on the Hofmeister series.

  13. Catalytic ozonation of bisphenol A in aqueous solution using Mn-Ce/HZSM-5 as catalyst.

    Science.gov (United States)

    Liu, Yanfang; Zhao, Junna; Li, Zaixing; Li, Guixia; Li, Wei; Gao, Xiang

    2015-01-01

    Mixed manganese and cerium oxide supported on HZSM-5 were synthesized and used as heterogeneous catalysts for ozonation of bisphenol A (BPA) in aqueous solution. The prepared catalysts of Mn-Ce/HZSM-5 were characterized by X-ray diffraction, scanning electron microscopy and Fourier transform-infrared spectroscopy. The results indicated that Mn-Ce/HZSM-5 exhibits extraordinary catalytic activity for the degradation of BPA. Removal of 89.3% of BPA and 90.4% of total organic carbon (TOC) was achieved in 30 min, compared to non-catalytic ozonation, where only 50.5% BPA and 28.1% TOC removal were reached under the same conditions. Adsorption of BPA on HZSM-5 support and Mn-Ce/HZSM-5 catalysts was negligible. The strong inhibition of BPA removal by tert-butyl alcohol indicated that the attack of hydroxyl radicals was responsible for the improvement of catalytic ozonation. It was observed that at neutral pH, which is near the point of zero charge of the catalyst, the catalytic activity reached its maximum. Increasing the amount of Mn-Ce/HZSM-5 catalyst until it exceeded 3 g/L did not show a strong effect on BPA removal. The catalysts showed high stability and reusability.

  14. Reduction of highly concentrated phosphate from aqueous solution using pectin-nanoscale zerovalent iron (PNZVI).

    Science.gov (United States)

    Wang, Hongyu; Zou, Zhuocheng; Xiao, Xuelian; Chen, Dan; Yang, Kai

    2016-01-01

    Pectin-nanoscale zerovalent iron (PNZVI) has been studied as an effective phosphate adsorption material to remove highly concentrated phosphate from aqueous solution. Batch phosphate removal and equilibrium experiments were conducted in order to evaluate the effects of environmental factors such as pH, coexisting anions and ionic strengths on phosphate removal by PNZVI. The scanning electron microscope images of nanoscale zerovalent iron (NZVI) and PNZVI demonstrated that PNZVI exhibited larger specific surface areas than NZVI so that PNZVI had higher phosphate removal efficiency than NZVI. Equilibrium experiments showed that phosphate adsorption by PNZVI was well fitted with the Freundlich and Langmuir models. In addition, the maximum adsorption capacity reached 277.38 mgP/gPNZVI. The ionic strengths and common anions showed no significant effects on the process of phosphate adsorption by PNZVI. The phosphate removal efficiency increased to a peak value with pH increased from 2.0 to 5.0, then decreased with pH further increased from 5.0 to 10.0. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses of PNZVI and P-loaded PNZVI indicated that adsorption, rather than redox reaction, was the dominant mechanism for the removal of phosphate by PNZVI.

  15. Assembly of DNA Architectures in a Non-Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Thomas J. Proctor

    2012-08-01

    Full Text Available In the present work, the procedures for the creation of self-assembled DNA nanostructures in aqueous and non-aqueous media are described. DNA-Surfactant complex formation renders the DNA soluble in organic solvents offering an exciting way to bridge the transition of DNA origami materials electronics applications. The DNA retains its structural features, and these unique geometries provide an interesting candidate for future electronics and nanofabrication applications with potential for new properties. The DNA architectures were first assembled under aqueous conditions, and then characterized in solution (using circular dichroism (CD spectroscopy and on the surface (using atomic force microscopy (AFM. Following aqueous assembly, the DNA nanostructures were transitioned to a non-aqueous environment, where butanol was chosen for optical compatibility and thermal properties. The retention of DNA hierarchical structure and thermal stability in non-aqueous conditions were confirmed via CD spectroscopy. The formation and characterization of these higher order DNA-surfactant complexes is described in this paper.

  16. Critical droplet theory explains the glass formability of aqueous solutions.

    Science.gov (United States)

    Warkentin, Matthew; Sethna, James P; Thorne, Robert E

    2013-01-04

    When pure water is cooled at ~10(6) K / s, it forms an amorphous solid (glass) instead of the more familiar crystalline phase. The presence of solutes can reduce this required (or "critical") cooling rate by orders of magnitude. Here, we present critical cooling rates for a variety of solutes as a function of concentration and a theoretical framework for understanding these rates. For all solutes tested, the critical cooling rate is an exponential function of concentration. The exponential's characteristic concentration for each solute correlates with the solute's Stokes radius. A modification of critical droplet theory relates the characteristic concentration to the solute radius and the critical nucleation radius of ice in pure water. This simple theory of ice nucleation and glass formability in aqueous solutions has consequences for general glass-forming systems, and in cryobiology, cloud physics, and climate modeling.

  17. Auger electron and X-ray photoelectron spectroscopic study of the biocorrosion of copper by alginic acid polysaccharide

    Science.gov (United States)

    Jolley, John G.; Geesey, Gill G.; Hankins, Michael R.; Wright, Randy B.; Wichlacz, Paul L.

    1989-08-01

    Thin films (3.4 nm) of copper on germanium substrates were exposed to 2% alginic acid polysaccharide aqueous solution. Pre- and post-exposure characterization were done by Auger electron spectroscopy and X-ray photoelectron spectroscopy. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium substrate. Results indicate that some of the copper was oxidized by the alginic acid solution. Some of the copper was removed from the Cu/Ge interface and incorporated into the polymer matrix. Thus, biocorrosion of copper was exhibited by the alginic acid polysaccharide.

  18. Controlling X-rays With Light

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Diffractive X-Ray Telescopes

    Science.gov (United States)

    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.

  20. Diffractive X-ray Telescopes

    CERN Document Server

    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 several 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 space- time 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.