Role of solution structure in self-assembly of conjugated block copolymer thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brady, Michael A.; Ku, Sung -Yu; Perez, Louis A.

Conjugated block copolymers provide a pathway to achieve thermally stable nanostructured thin films for organic solar cells. We characterized the structural evolution of poly(3-hexylthiophene)- block-poly(diketopyrrolopyrrole–terthiophene) (P3HT- b-DPPT-T) from solution to nanostructured thin films. Aggregation of the DPPT-T block of P3HT- b-DPPT-T was found in solution by small-angle X-ray scattering with the P3HT block remaining well-solvated. The nanostructure in thin films was determined using a combination of wide and small-angle X-ray scattering techniques as a function of processing conditions. The structure in solution controlled the initial nanostructure in spin-cast thin films, allowing subsequent thermal annealing processes to further improve the ordering.more » In contrast to the results for thin films, nanostructural ordering was not observed in the bulk samples by small-angle X-ray scattering. Finally, these results suggest the importance of controlling solvent induced aggregation in forming nanostructured thin films of conjugated block copolymers.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazalova, M; Ahmad, M; Fahrig, R

Purpose: To evaluate x-ray fluorescence computed tomography induced with proton beams (pXFCT) for imaging of gold contrast agent. Methods: Proton-induced x-ray fluorescence was studied by means of Monte Carlo (MC) simulations using TOPAS, a MC code based on GEANT4. First, proton-induced K-shell and L-shell fluorescence was studied as a function of proton beam energy and 1) depth in water and 2) size of contrast object. Second, pXFCT images of a 2-cm diameter cylindrical phantom with four 5- mm diameter contrast vials and of a 20-cm diameter phantom with 1-cm diameter vials were simulated. Contrast vials were filled with water andmore » water solutions with 1-5% gold per weight. Proton beam energies were varied from 70-250MeV. pXFCT sinograms were generated based on the net number of gold K-shell or L-shell x-rays determined by interpolations from the neighboring 0.5keV energy bins of spectra collected with an idealized 4π detector. pXFCT images were reconstructed with filtered-back projection, and no attenuation correction was applied. Results: Proton induced x-ray fluorescence spectra showed very low background compared to x-ray induced fluorescence. Proton induced L-shell fluorescence had a higher cross-section compared to K-shell fluorescence. Excitation of L-shell fluorescence was most efficient for low-energy protons, i.e. at the Bragg peak. K-shell fluorescence increased with increasing proton beam energy and object size. The 2% and 5% gold contrast vials were accurately reconstructed in K-shell pXFCT images of both the 2-cm and 20-cm diameter phantoms. Small phantom L-shell pXFCT image required attenuation correction and had a higher sensitivity for 70MeV protons compared to 250MeV protons. With attenuation correction, L-shell pXFCT might be a feasible option for imaging of small size (∼2cm) objects. Imaging doses for all simulations were 5-30cGy. Conclusion: Proton induced x-ray fluorescence CT promises to be an alternative quantitative imaging technique to the commonly considered XFCT imaging with x-ray beams.« less

Direct X-ray photoconversion in flexible organic thin film devices operated below 1 V

PubMed Central

Basiricò, Laura; Ciavatti, Andrea; Cramer, Tobias; Cosseddu, Piero; Bonfiglio, Annalisa; Fraboni, Beatrice

2016-01-01

The application of organic electronic materials for the detection of ionizing radiations is very appealing thanks to their mechanical flexibility, low-cost and simple processing in comparison to their inorganic counterpart. In this work we investigate the direct X-ray photoconversion process in organic thin film photoconductors. The devices are realized by drop casting solution-processed bis-(triisopropylsilylethynyl)pentacene (TIPS-pentacene) onto flexible plastic substrates patterned with metal electrodes; they exhibit a strong sensitivity to X-rays despite the low X-ray photon absorption typical of low-Z organic materials. We propose a model, based on the accumulation of photogenerated charges and photoconductive gain, able to describe the magnitude as well as the dynamics of the X-ray-induced photocurrent. This finding allows us to fabricate and test a flexible 2 × 2 pixelated X-ray detector operating at 0.2 V, with gain and sensitivity up to 4.7 × 104 and 77,000 nC mGy−1 cm−3, respectively. PMID:27708274

Freezing-induced self-assembly of amphiphilic molecules

NASA Astrophysics Data System (ADS)

Albouy, P. A.; Deville, S.; Fulkar, A.; Hakouk, K.; Impéror-Clerc, M.; Klotz, M.; Liu, Q.; Marcellini, M.; Perez, J.

The self-assembly of amphiphilic molecules usually takes place in a liquid phase, near room temperature. Here, using small angle X-ray scattering (SAXS) experiments performed in real time, we show that freezing of aqueous solutions of copolymer amphiphilic molecules can induce self-assembly below 0{\\deg}C.

Freezing-induced self-assembly of amphiphilic molecules.

PubMed

Albouy, P A; Deville, S; Fulkar, A; Hakouk, K; Impéror-Clerc, M; Klotz, M; Liu, Q; Marcellini, M; Perez, J

2017-03-01

The self-assembly of amphiphilic molecules usually takes place in a liquid phase, near room temperature. Here, using small angle X-ray scattering (SAXS) experiments performed in real time, we show that freezing of aqueous solutions of copolymer amphiphilic molecules can induce self-assembly below 0 °C.

Reconstruction of viruses from solution x-ray scattering data

NASA Astrophysics Data System (ADS)

Zheng, Yibin; Doerschuk, Peter C.; Johnson, John E.

1995-08-01

A model-based method for reconstructing the 3D structure of icosahedrally-symmetric viruses from solution x-ray scattering is presented. An example of the reconstruction, for data from cowpea mosaic virus, is described. The major opportunity provided by solution x-ray scattering is the ability to study the dynamics of virus particles in solution, information that is not accessible to crystal x-ray diffraction experiments.

Influence of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) on zinc electrodeposition

NASA Astrophysics Data System (ADS)

Lehr, I. L.; Saidman, S. B.

2012-03-01

This work is a study of the electrodeposition of zinc onto SAE 4140 steel electrodes using solutions containing zinc sulfate and bis(2-ethylhexyl) sodium sulfosuccinate (AOT). The influence of different parameters such as electrolyte concentration, electrodeposition time and temperature on the morphology of the electrodeposits was analyzed. The deposits were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction. The variation of open circuit potential over time in chloride solutions was also evaluated. The nucleation-growth process and consequently the morphology of the electrodeposits are modified in the presence of AOT. The surfactant induces the formation of a porous deposit.

Direct printing of microstructures by femtosecond laser excitation of nanocrystals in solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shou, Wan; Pan, Heng, E-mail: hp5c7@mst.edu

2016-05-23

We report direct printing of micro/sub-micron structures by femtosecond laser excitation of semiconductor nanocrystals (NCs) in solution. Laser excitation with moderate intensity (10{sup 11}–10{sup 12} W/cm{sup 2}) induces 2D and 3D deposition of CdTe nanocrystals in aqueous solution, which can be applied for direct printing of microstructures. It is believed that laser irradiation induces charge formation on nanocrystals leading to deposition. Furthermore, it is demonstrated that the charged nanocrystals can respond to external electrical bias, enabling a printing approach based on selective laser induced electrophoretic deposition. Finally, energy dispersive X-ray analysis of deposited structures shows oxidation occurs and deposited structure mainlymore » consists of Cd{sub x}O.« less

Local Structure and Short-Range Order in a NiCoCr Solid Solution Alloy

DOE PAGES

Zhang, F. X.; Zhao, Shijun; Jin, Ke; ...

2017-05-19

Multi-element solid solution alloys are intrinsically disordered on the atomic scale, and many of their advanced properties originate from the unique local structural characteristics. We measured the local structure of a NiCoCr solid solution alloy with X-ray/neutron total scattering and extended X-ray absorption fine structure (EXAFS) techniques. The atomic pair distribution function analysis (PDF) did not exhibit distinct structural distortion. But, EXAFS analysis suggested that the Cr atoms are favorably bonded with Ni and Co in the solid solution alloys. This short-range order (SRO) plays a role in the distinct low values of electrical and thermal conductivities in Ni-based solidmore » solution alloys when Cr is incorporated. Both the long-range and local structures of the NiCoCr alloy upon Ni ion irradiation were studied and an irradiation-induced enhancement of SRO was found.« less

Direct-write maskless lithography using patterned oxidation of Si-substrate Induced by femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Kiani, Amirkianoosh; Venkatakrishnan, Krishnan; Tan, Bo

2013-03-01

In this study we report a new method for direct-write maskless lithography using oxidized silicon layer induced by high repetition (MHz) ultrafast (femtosecond) laser pulses under ambient condition. The induced thin layer of predetermined pattern can act as an etch stop during etching process in alkaline etchants such as KOH. The proposed method can be leading to promising solutions for direct-write maskless lithography technique since the proposed method offers a higher degree of flexibility and reduced time and cost of fabrication which makes it particularly appropriate for rapid prototyping and custom scale manufacturing. A Scanning Electron Microscope (SEM), Micro-Raman, Energy Dispersive X-ray (EDX), optical microscope and X-ray diffraction spectroscopy (XRD) were used to evaluate the quality of oxidized layer induced by laser pulses.

Targeted Delivery of Chemotherapeutic Agents Using Improved Radiosensitive Liquid Core Microcapsules and Assessment of Their Antitumor Effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harada, Satoshi; Ehara, Shigeru; Ishii, Keizo

2009-10-01

Purpose: Radiation-sensitive microcapsules composed of alginate and hyaluronic acid are being developed. We report the development of improved microcapsules that were prepared using calcium- and yttrium-induced polymerization. We previously reported on the combined antitumor effect of carboplatin-containing microcapsules and radiotherapy. Methods and Materials: We mixed a 0.1% (wt/vol) solution of hyaluronic acid with a 0.2% alginate solution. Carboplatin (l mg) and indocyanine green (12.5 {mu}g) were added to this mixture, and the resultant material was used for capsule preparation. The capsules were prepared by spraying the material into a mixture containing a 4.34% CaCl{sub 2} solution supplemented with 0-0.01% yttrium.more » These capsules were irradiated with single doses of 0.5, 1.0, 1.5, or 2 Gy {sup 60}Co {gamma}-rays. Immediately after irradiation, the frequency of microcapsule decomposition was determined using a microparticle-induced X-ray emission camera. The amount of core content released was estimated by particle-induced X-ray emission and colorimetric analysis with 0.25% indocyanine green. The antitumor effect of the combined therapy was determined by monitoring its effects on the diameter of an inoculated Meth A fibrosarcoma. Results: Microcapsules that had been polymerized using a 4.34% CaCl{sub 2} solution supplemented with 5.0 x 10{sup -3}% (10{sup -3}% meant or 10%{sup -3}) yttrium exhibited the maximal decomposition, and the optimal release of core content occurred after 2-Gy irradiation. The microcapsules exhibited a synergistic antitumor effect combined with 2-Gy irradiation and were associated with reduced adverse effects. Conclusion: The results of our study have shown that our liquid core microcapsules can be used in radiotherapy for targeted delivery of chemotherapeutic agents.« less

Gamma-radiolytic preparation of multi-component oxides

NASA Astrophysics Data System (ADS)

Procházková, Lenka; Bárta, Jan; Čuba, Václav; Ekberg, Christian; Tietze, Sabrina; Jakubec, Ivo

2016-07-01

The preparation of solid precursors to Zn1-xCdxO and (Lu,Y)3Al5O12:Ce induced by 60Co gamma-ray irradiation of aqueous solutions containing soluble metal salts and ammonium formate is presented. Due to the irradiation, crystalline zinc carbonate hydroxide Zn4(CO3)(OH)6·H2O or amorphous carbonates of Lu, Y and Al were formed in the solutions. After calcination at 500 °C, the agglomerated phase-pure Zn1-xCdxO with crystallite size about 50 nm was obtained if the Cd concentration in solutions remained below 16 M% (with respect to Zn) with x being up to 0.035. The solid precursors to garnets contained the intended concentration of all elements, according to X-ray fluorescence analysis. After calcination at 1200 °C in mild vacuum, the respective phase-pure garnets with crystallite size 100 nm or their solid solution were produced when the Ce dopation was kept below 2 M% (with respect to rare-earth metals). The Ce solubility in the garnet lattice was estimated as 1-2 M% at the calcination conditions used.

Confinement-induced liquid ordering investigated by x-ray phase retrieval

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bunk, Oliver; Diaz, Ana; Pfeiffer, Franz

2007-02-15

Using synchrotron x-ray diffraction, we have determined the ensemble-averaged density profile of colloidal fluids within confining channels of different widths. We observe an oscillatory ordering-disordering behavior of the colloidal particles as a function of the channel width, while the colloidal solution remains in the liquid state. This phenomenon has been suggested by surface force studies of hard-sphere fluids and also theoretically predicted, but here we see it by direct measurements of the structure for comparable systems.

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

NASA Astrophysics Data System (ADS)

Py, J.; Groetz, J.-E.; Hubinois, J.-C.; Cardona, D.

2015-04-01

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-1 is given.

Mutagenic synergism detected between dimethyl sulfate and X-rays but not found between N-methyl-N-nitrosourea and X-rays in the stamen hairs of Tradescantia clone BNL 4430.

PubMed

Shima, N; Ichikawa, S

1995-09-01

Mutagenic interactions with X-rays of two monofunctional alkylating agents, dimethyl sulfate (DMS) and N-methyl-N-nitrosourea (MNU), were studied in the stamen hairs of Tradescantia clone BNL 4430, a blue/pink heterozygote. The young inflorescence-bearing shoots with roots cultivated in the nutrient solution circulating growth chamber were used as tester plants. Synergism between two different mutagens was judged to have occurred when the mutation frequency observed after applying the two mutagens concurrently was statistically significantly higher than the mutation frequency expected from the additive effects of the two mutagens. Clear synergistic effects in inducing somatic pink mutations were detected with all combinations of doses of DMS and X-rays examined, even in a relatively low X-ray dose range (down to 299 mGy), resembling those confirmed earlier between ethyl methanesulfonate (EMS) and X-rays, but somewhat differing from the synergisms observed earlier between methyl methanesulfonate (MMS) and X-rays. On the other hand, no mutagenic synergism was detected between MNU and X-rays, even in a relatively high X-ray dose range (up to 862 mGy). The presence or absence of mutagenic synergisms of these alkylating agents with X-rays could be related to the action mechanism of each alkylating agent.

High-pressure-assisted X-ray-induced damage as a new route for materials synthesis

DOE PAGES

Evlyukhin, Egor; Kim, Eunja; Goldberger, David; ...

2018-01-01

X-ray radiation induced damage has been known for decades and has largely been viewed as a tremendous nuisance; e.g., most X-ray-related studies of organic and inorganic materials suffer X-ray damage to varying degrees. Although, recent theoretical and experimental investigation of the response of simple chemical systems to X-rays offered better understanding of the mechanistic details of X-ray induced damage, the question about useful applicability of this technique is still unclear. Furthermore we experimentally demonstrate that by tuning pressure and X-ray energy, the radiation induced damage can be controlled and used for synthesis of novel materials.

Radiation induced deposition of copper nanoparticles inside the nanochannels of poly(acrylic acid)-grafted poly(ethylene terephthalate) track-etched membranes

NASA Astrophysics Data System (ADS)

Korolkov, Ilya V.; Güven, Olgun; Mashentseva, Anastassiya A.; Atıcı, Ayse Bakar; Gorin, Yevgeniy G.; Zdorovets, Maxim V.; Taltenov, Abzal A.

2017-01-01

Poly(ethylene terephthalate) PET, track-etched membranes (TeMs) with 400 nm average pore size were UV-grafted with poly(acrylic acid) (PAA) after oxidation of inner surfaces by H2O2/UV system. Carboxylate groups of grafted PAA chains were easily complexed with Cu2+ ions in aqueous solutions. These ions were converted into metallic copper nanoparticles (NPs) by radiation-induced reduction of copper ions in aqueous-alcohol solution by gamma rays in the dose range of 46-250 kGy. Copper ions chelating with -COOH groups of PAA chains grafted on PET TeMs form polymer-metal ion complex that prevent the formation of agglomerates during reduction of copper ions to metallic nanoparticles. The detailed analysis by X-Ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the deposition of copper nanoparticles with the average size of 70 nm on the inner surface of nanochannels of PET TeMs. Samples were also investigated by FTIR, ESR spectroscopies to follow copper ion reduction.

Roles of oxidative stress in synchrotron radiation X-ray-induced testicular damage of rodents

PubMed Central

Ma, Yingxin; Nie, Hui; Sheng, Caibin; Chen, Heyu; Wang, Ban; Liu, Tengyuan; Shao, Jiaxiang; He, Xin; Zhang, Tingting; Zheng, Chaobo; Xia, Weiliang; Ying, Weihai

2012-01-01

Synchrotron radiation (SR) X-ray has characteristic properties such as coherence and high photon flux, which has excellent potential for its applications in medical imaging and cancer treatment. However, there is little information regarding the mechanisms underlying the damaging effects of SR X-ray on biological tissues. Oxidative stress plays an important role in the tissue damage induced by conventional X-ray, while the role of oxidative stress in the tissue injury induced by SR X-ray remains unknown. In this study we used the male gonads of rats as a model to study the roles of oxidative stress in SR X-ray-induced tissue damage. Exposures of the testes to SR X-ray at various radiation doses did not significantly increase the lipid peroxidation of the tissues, assessed at one day after the irradiation. No significant decreases in the levels of GSH or total antioxidation capacity were found in the SR X-ray-irradiated testes. However, the SR X-ray at 40 Gy induced a marked increase in phosphorylated H2AX – a marker of double-strand DNA damage, which was significantly decreased by the antioxidant N-acetyl cysteine (NAC). NAC also attenuated the SR X-ray-induced decreases in the cell layer number of seminiferous tubules. Collectively, our observations have provided the first characterization of SR X-ray-induced oxidative damage of biological tissues: SR X-ray at high doses can induce DNA damage and certain tissue damage during the acute phase of the irradiation, at least partially by generating oxidative stress. However, SR X-ray of various radiation doses did not increase lipid peroxidation. PMID:22837810

Detecting element specific electrons from a single cobalt nanocluster with synchrotron x-ray scanning tunneling microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kersell, Heath; Shirato, Nozomi; Cummings, Marvin

We use a nanofabricated scanning tunneling microscope tip as a detector to investigate local X-ray induced tunneling and electron emission from a single cobalt nanocluster on a Au(111) surface. The tip-detector is positioned a few angstroms above the nanocluster, and ramping the incident X-ray energy across the Co photoabsorption K-edge enables the detection of element specific electrons. Atomic-scale spatial dependent changes in the X-ray absorption cross section are directly measured by taking the X-ray induced current as a function of X-ray energy. From the measured sample and tip currents, element specific X-ray induced current components can be separated and therebymore » the corresponding yields for the X-ray induced processes of the single cobalt nanocluster can be determined. The detection of element specific synchrotron X-ray induced electrons of a single nanocluster opens a new avenue for materials characterization on a one particle at-a-time basis.« less

Detecting element specific electrons from a single cobalt nanocluster with synchrotron x-ray scanning tunneling microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kersell, Heath; Shirato, Nozomi; Cummings, Marvin

Here, we use a nanofabricated scanning tunneling microscope tip as a detector to investigate local X-ray induced tunneling and electron emission from a single cobalt nanocluster on a Au(111) surface. The tip-detector is positioned a few angstroms above the nanocluster, and ramping the incident X-ray energy across the Co photoabsorption K-edge enables the detection of element specific electrons. Atomic-scale spatial dependent changes in the X-ray absorption cross section are directly measured by taking the X-ray induced current as a function of X-ray energy. From the measured sample and tip currents, element specific X-ray induced current components can be separated andmore » thereby the corresponding yields for the X-ray induced processes of the single cobalt nanocluster can be determined. The detection of element specific synchrotron X-ray induced electrons of a single nanocluster opens a new avenue for materials characterization on a one particle at-a-time basis.« less

Detecting element specific electrons from a single cobalt nanocluster with synchrotron x-ray scanning tunneling microscopy

DOE PAGES

Kersell, Heath; Shirato, Nozomi; Cummings, Marvin; ...

2017-09-05

Here, we use a nanofabricated scanning tunneling microscope tip as a detector to investigate local X-ray induced tunneling and electron emission from a single cobalt nanocluster on a Au(111) surface. The tip-detector is positioned a few angstroms above the nanocluster, and ramping the incident X-ray energy across the Co photoabsorption K-edge enables the detection of element specific electrons. Atomic-scale spatial dependent changes in the X-ray absorption cross section are directly measured by taking the X-ray induced current as a function of X-ray energy. From the measured sample and tip currents, element specific X-ray induced current components can be separated andmore » thereby the corresponding yields for the X-ray induced processes of the single cobalt nanocluster can be determined. The detection of element specific synchrotron X-ray induced electrons of a single nanocluster opens a new avenue for materials characterization on a one particle at-a-time basis.« less

Resonant soft X-ray scattering on protein solutions

NASA Astrophysics Data System (ADS)

Ye, Dan; Le, Thinh; Wang, Cheng; Zwart, Peter; Gomez, Esther; Gomez, Enrique

Protein structure is crucial for biological function, such that characterizing protein folding and packing is important for the design of therapeutics and enzymes. We propose resonant soft X-ray scattering (RSOXS) as an approach to study proteins and other biological assemblies in solution. Calculations of the scattering contrast suggest that soft X-ray scattering is more sensitive than hard X-ray scattering, because of contrast generated at the absorption edges of constituent elements such as carbon, nitrogen and oxygen. We have examined the structure of bovine serum albumin (BSA) in solution by RSOXS. We find that by varying incident X-ray energies, we are able to achieve higher scattering contrast near the absorption edge. From our RSOXS scattering result we are able to reconstruct the structure of BSA in 3D. These RSOXS results also agree with hard X-ray experiments, including crystallographic data. Our study demonstrates the potential of RSOXS for studying protein structure in solution.

NAD+ administration significantly attenuates synchrotron radiation X-ray-induced DNA damage and structural alterations of rodent testes

PubMed Central

Sheng, Caibin; Chen, Heyu; Wang, Ban; Liu, Tengyuan; Hong, Yunyi; Shao, Jiaxiang; He, Xin; Ma, Yingxin; Nie, Hui; Liu, Na; Xia, Weiliang; Ying, Weihai

2012-01-01

Synchrotron radiation (SR) X-ray has great potential for its applications in medical imaging and cancer treatment. In order to apply SR X-ray in clinical settings, it is necessary to elucidate the mechanisms underlying the damaging effects of SR X-ray on normal tissues, and to search for the strategies to reduce the detrimental effects of SR X-ray on normal tissues. However, so far there has been little information on these topics. In this study we used the testes of rats as a model to characterize SR X-ray-induced tissue damage, and to test our hypothesis that NAD+ administration can prevent SR X-ray-induced injury of the testes. We first determined the effects of SR X-ray at the doses of 0, 0.5, 1.3, 4 and 40 Gy on the biochemical and structural properties of the testes one day after SR X-ray exposures. We found that 40 Gy of SR X-ray induced a massive increase in double-strand DNA damage, as assessed by both immunostaining and Western blot of phosphorylated H2AX levels, which was significantly decreased by intraperitoneally (i.p.) administered NAD+ at doses of 125 and 625 mg/kg. Forty Gy of SR X-ray can also induce marked increases in abnormal cell nuclei as well as significant decreases in the cell layers of the seminiferous tubules one day after SR X-ray exposures, which were also ameliorated by the NAD+ administration. In summary, our study has shown that SR X-ray can produce both molecular and structural alterations of the testes, which can be significantly attenuated by NAD+ administration. These results have provided not only the first evidence that SR X-ray-induced tissue damage can be ameliorated by certain approaches, but also a valuable basis for elucidating the mechanisms underlying SR X-ray-induced tissue injury. PMID:22518270

Morphological transformations in the magnetite biomineralizing protein Mms6 in iron solutions: A small-angle x-ray scattering study

DOE PAGES

Zhang, Honghu; Liu, Xunpei; Feng, Shuren; ...

2015-02-10

In this study, magnetotactic bacteria that produce magnetic nanocrystals of uniform size and well-defined morphologies have inspired the use of biomineralization protein Mms6 to promote formation of uniform magnetic nanocrystals in vitro. Small angle X-ray scattering (SAXS) studies in physiological solutions reveal that Mms6 forms compact globular three-dimensional (3D) micelles (approximately 10 nm in diameter) that are, to a large extent, independent of concentration. In the presence of iron ions in the solutions, the general micellar morphology is preserved, however, with associations among micelles that are induced by iron ions. Compared with Mms6, the m2Mms6 mutant (with the sequence ofmore » hydroxyl/carboxyl containing residues in the C-terminal domain shuffled) exhibits subtle morphological changes in the presence of iron ions in solutions. The analysis of the SAXS data is consistent with a hierarchical core–corona micellar structure similar to that found in amphiphilic polymers. The addition of ferric and ferrous iron ions to the protein solution induces morphological changes in the micellar structure by transforming the 3D micelles into objects of reduced dimensionality of 2, with fractal-like characteristics (including Gaussian-chain-like) or, alternatively, platelet-like structures.« less

Dose-rate plays a significant role in synchrotron radiation X-ray-induced damage of rodent testes.

PubMed

Chen, Heyu; Wang, Ban; Wang, Caixia; Cao, Wei; Zhang, Jie; Ma, Yingxin; Hong, Yunyi; Fu, Shen; Wu, Fan; Ying, Weihai

2016-01-01

Synchrotron radiation (SR) X-ray has significant potential for applications in medical imaging and cancer treatment. However, the mechanisms underlying SR X-ray-induced tissue damage remain unclear. Previous studies on regular X-ray-induced tissue damage have suggested that dose-rate could affect radiation damage. Because SR X-ray has exceedingly high dose-rate compared to regular X-ray, it remains to be determined if dose-rate may affect SR X-ray-induced tissue damage. We used rodent testes as a model to investigate the role of dose-rate in SR X-ray-induced tissue damage. One day after SR X-ray irradiation, we determined the effects of the irradiation of the same dosage at two different dose-rates, 0.11 Gy/s and 1.1 Gy/s, on TUNEL signals, caspase-3 activation and DNA double-strand breaks (DSBs) of the testes. Compared to those produced by the irradiation at 0.11 Gy/s, irradiation at 1.1 Gy/s produced higher levels of DSBs, TUNEL signals, and caspase-3 activation in the testes. Our study has provided the first evidence suggesting that dose-rate could be a significant factor in SR X-ray-induced tissue damage, which may establish a valuable base for utilizing this factor to manipulate the tissue damage in SR X-ray-based medical applications.

Dose-rate plays a significant role in synchrotron radiation X-ray-induced damage of rodent testes

PubMed Central

Chen, Heyu; Wang, Ban; Wang, Caixia; Cao, Wei; Zhang, Jie; Ma, Yingxin; Hong, Yunyi; Fu, Shen; Wu, Fan; Ying, Weihai

2016-01-01

Synchrotron radiation (SR) X-ray has significant potential for applications in medical imaging and cancer treatment. However, the mechanisms underlying SR X-ray-induced tissue damage remain unclear. Previous studies on regular X-ray-induced tissue damage have suggested that dose-rate could affect radiation damage. Because SR X-ray has exceedingly high dose-rate compared to regular X-ray, it remains to be determined if dose-rate may affect SR X-ray-induced tissue damage. We used rodent testes as a model to investigate the role of dose-rate in SR X-ray-induced tissue damage. One day after SR X-ray irradiation, we determined the effects of the irradiation of the same dosage at two different dose-rates, 0.11 Gy/s and 1.1 Gy/s, on TUNEL signals, caspase-3 activation and DNA double-strand breaks (DSBs) of the testes. Compared to those produced by the irradiation at 0.11 Gy/s, irradiation at 1.1 Gy/s produced higher levels of DSBs, TUNEL signals, and caspase-3 activation in the testes. Our study has provided the first evidence suggesting that dose-rate could be a significant factor in SR X-ray-induced tissue damage, which may establish a valuable base for utilizing this factor to manipulate the tissue damage in SR X-ray-based medical applications. PMID:28078052

Glass transition in ferroic glass K x (ND4)1-x D2PO4: a complete x-ray diffraction line shape analysis

NASA Astrophysics Data System (ADS)

Ranjan Choudhury, Rajul; Chitra, R.; Jayakrishnan, V. B.

2016-03-01

Quenching of dynamic disorder in glassy systems is termed as the glass transition. Ferroic glasses belong to the class of paracrystalline materials having crystallographic order in-between that of a perfect crystal and amorphous material, a classic example of ferroic glass is the solid solution of ferroelectric deuterated potassium dihydrogen phosphate and antiferroelectric deuterated ammonium dihydrogen phosphate. Lowering temperature of this ferroic glass can lead to a glass transition to a quenched disordered state. The subtle atomic rearrangement that takes place at such a glass transition can be revealed by careful examination of the temperature induced changes occurring in the x-ray powder diffraction (XRD) patterns of these materials. Hence we report here results of a complete diffraction line shape analysis of the XRD patterns recorded at different temperatures from deuterated mixed crystals DK x A1-x DP with mixing concentration x ranging as 0 < x < 1. Changes observed in diffraction peak shapes have been explained on the basis of structural rearrangements induced by changing O-D-O hydrogen bond dynamics in these paracrystals.

Effects of chemo-mechanical polishing on CdZnTe X-ray and gamma-ray detectors

DOE PAGES

Egarievwe, Stephen E.; Hossain, Anwar; Okwechime, Ifechukwude O.; ...

2015-06-23

Here, mechanically polishing cadmium zinc telluride (CdZnTe) wafers for x-ray and gamma-ray detectors often is inadequate in removing surface defects caused by cutting them from the ingots. Fabrication-induced defects, such as surface roughness, dangling bonds, and nonstoichiometric surfaces, often are reduced through polishing and etching the surface. In our earlier studies of mechanical polishing with alumina powder, etching with hydrogen bromide in hydrogen peroxide solution, and chemomechanical polishing with bromine–methanol–ethylene glycol solution, we found that the chemomechanical polishing process produced the least surface leakage current. In this research, we focused on using two chemicals to chemomechanically polish CdZnTe wafers aftermore » mechanical polishing, viz. bromine–methanol–ethylene glycol (BME) solution, and hydrogen bromide (HBr) in a hydrogen peroxide and ethylene–glycol solution. We used x-ray photoelectron spectroscopy (XPS), current–voltage (I–V) measurements, and Am-241 spectral response measurements to characterize and compare the effects of each solution. The results show that the HBr-based solution produced lower leakage current than the BME solution. Results from using the same chemomechanical polishing solution on two samples confirmed that the surface treatment affects the measured bulk current (a combination of bulk and surface currents). XPS results indicate that the tellurium oxide to tellurium peak ratios for the mechanical polishing process were reduced significantly by chemomechanical polishing using the BME solution (78.9% for Te 3d 5/2O 2 and 76.7% for Te 3d 3/2O 2) compared with the HBr-based solution (27.6% for Te 3d 5/2O 2 and 35.8% for Te 3d 3/2O 2). Spectral response measurements showed that the 59.5-keV peak of Am-241 remained under the same channel number for all three CdZnTe samples. While the BME-based solution gave a better performance of 7.15% full-width at half-maximum (FWHM) compared with 7.59% FWHM for the HBr-based solution, the latter showed a smaller variation in performance of 0.39% FWHM over 7 days compared with 0.69% for the BME-based solution.« less

Chemical complexity induced local structural distortion in NiCoFeMnCr high-entropy alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Fuxiang; Tong, Yang; Jin, Ke

In order to study chemical complexity-induced lattice distortion in high-entropy alloys, the static Debye–Waller (D-W) factor of NiCoFeMnCr solid solution alloy is measured with low temperature neutron diffraction, ambient X-ray diffraction, and total scattering methods. Here, the static atomic displacement parameter of the multi-element component alloy at 0 K is 0.035–0.041 Å, which is obvious larger than that of element Ni (~0 Å). The atomic pair distance between individual atoms in the alloy investigated with extended X-ray absorption fine structure (EXAFS) measurements indicates that Mn has a slightly larger bond distance (~0.4%) with neighbor atoms than that of others.

Chemical complexity induced local structural distortion in NiCoFeMnCr high-entropy alloy

DOE PAGES

Zhang, Fuxiang; Tong, Yang; Jin, Ke; ...

2018-06-16

In order to study chemical complexity-induced lattice distortion in high-entropy alloys, the static Debye–Waller (D-W) factor of NiCoFeMnCr solid solution alloy is measured with low temperature neutron diffraction, ambient X-ray diffraction, and total scattering methods. Here, the static atomic displacement parameter of the multi-element component alloy at 0 K is 0.035–0.041 Å, which is obvious larger than that of element Ni (~0 Å). The atomic pair distance between individual atoms in the alloy investigated with extended X-ray absorption fine structure (EXAFS) measurements indicates that Mn has a slightly larger bond distance (~0.4%) with neighbor atoms than that of others.

A method to visualize transdermal nickel permeation in mouse skin using a nickel allergy patch

PubMed Central

Sugiyama, Tomoko; Uo, Motohiro; Wada, Takahiro; Hongo, Toshio; Omagari, Daisuke; Komiyama, Kazuo; Oikawa, Masakazu; Kusama, Mikio; Mori, Yoshiyuki

2015-01-01

Metal patch test is often used in clinical settings when metal-induced contact dermatitis is suspected. However, the transdermal permeation behavior of metal ions from the patch test remains unclear. Current patch tests using high concentrations of metal salt solutions have some side effects, e.g. acute skin reactions to high concentrations of metal salt. To resolve these, estimating metal ion transdermal permeation is wished. In this study, synchrotron radiation X-ray fluorescence (SR-XRF) and micro-focused particle-induced X-ray emission (micro-PIXE) were used to visualize the time-dependent Ni permeation in mouse skin. The cross-sectional diffusion of Ni was visualized in a time-dependent manner. Our results indicate that maximum Ni permeation occurs after 24 h of patch treatment, and the permeated Ni content was high in the epidermis and spread into the dermis beyond the basal layer. This method may be useful to determine the appropriate solution concentration and duration of administration for the patch test. PMID:26484550

Cd(1-x)Zn(x)O [0.05 ≤x≤ 0.26] synthesized by vapor-diffusion induced hydrolysis and co-nucleation from aqueous metal salt solutions.

PubMed

Schwenzer, Birgit; Neilson, James R; Jeffries, Stacie M; Morse, Daniel E

2011-02-14

Nanoparticulate Cd(1-x)Zn(x)O (x = 0, 0.05-0.26, 1) is synthesized in a simple two-step synthesis approach. Vapor-diffusion induced catalytic hydrolysis of two molecular precursors at low temperature induces co-nucleation and polycondensation to produce bimetallic layered hydroxide salts (M = Cd, Zn) as precursor materials which are subsequently converted to Cd(1-x)Zn(x)O at 400 °C. Unlike ternary materials prepared by standard co-precipitation procedures, all products presented here containing < 30 mol% Zn(2+) ions are homogeneous in elemental composition on the micrometre scale. This measured compositional homogeneity within the samples, as determined by energy dispersive spectroscopy and inductively coupled plasma spectroscopy, is a testimony to the kinetic control achieved by employing slow hydrolysis conditions. In agreement with this observation, the optical properties of the materials obey Vegard's Law for a homogeneous solid solution of Cd(1-x)Zn(x)O, where x corresponds to the values determined by inductively coupled plasma analysis, even though powder X-ray diffraction shows phase separation into a cubic mixed metal oxide phase and a hexagonal ZnO phase at all doping levels.

Modeling of the EUV and X-Ray Emission Spectra Induced by the Solar Winds Ions in the Heliosphere

NASA Technical Reports Server (NTRS)

Kharchenko, Vasili

2005-01-01

We have carried out investigation of the EUV and X-ray emission spectra induced in interaction between the Solar Wind (SW) and interstellar neutral gas. The spectra of most important SW ions have been computed for the charge-exchange mechanism of X-ray emission using new accurate spectroscopic data from recent laboratory measurements and theoretical calculations. Total spectra have been constructed as a sum of spectra induced in the charge-exchange collisions by individual O(exp q+), C(exp q+), N(exp q+), Ne(exp q+), Mg (exp q+) and Fe(exp q+) ions. Calculations have been performed for X-ray emission from the heliospheric hydrogen and helium gas. X-ray maps of the heliosphere have been computed. The power density of X-ray sources in the heliospheric ecliptic plane is shown for the H gas and for the He gas. Distances from the Sun (0,0) are given in AU. The helium cone is clear seen in the X-ray map of the charge-exchange emission induced by the solar wind. X-ray emission spectra detected by the Chandra X-ray telescope from the "dark" side of Moon has been identified as a X-ray background emission induced by the solar wind from the geocorona. Spectra and intensities of this charge-exchange X-rays have been compared with the heliospheric component of the X-ray background. Observations and modeling of the SW spectra induced from the geocorona indicate a strong presence of emission lines of highly charged oxygen ions. Anisotropy in distribution of heliospheric X-rays has been predicted and calculated for the regions of the fast and slow solar winds.

Direct Observation of Insulin Association Dynamics with Time-Resolved X-ray Scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rimmerman, Dolev; Leshchev, Denis; Hsu, Darren J.

Biological functions frequently require protein-protein interactions that involve secondary and tertiary structural perturbation. Here we study protein-protein dissociation and reassociation dynamics in insulin, a model system for protein oligomerization. Insulin dimer dissociation into monomers was induced by a nanosecond temperature-jump (T-jump) of ~8 °C in aqueous solution, and the resulting protein and solvent dynamics were tracked by time-resolved X-ray solution scattering (TRXSS) on time scales of 10 ns to 100 ms. The protein scattering signals revealed the formation of five distinguishable transient species during the association process that deviate from simple two state kinetics. Our results show that the combinationmore » of T-jump pump coupled to TRXSS probe allows for direct tracking of structural dynamics in nonphotoactive proteins.« less

Supercrystallization of KCl from solution irradiated by soft X-rays

NASA Astrophysics Data System (ADS)

Janavičius, A. J.; Rinkūnas, R.; Purlys, R.

2016-10-01

The X-rays influence on KCl crystallization in a saturated water solution has been investigated for the aim of comparing it with previously considered NaCl crystallization. The rate of crystallization has been measured in the drying drop in the solution activated by the irradiation. We have measured the influence of the irradiation time of the solution on the rates of KCl crystallization as well as the beginning of the crystallization processes on drying drops. For a longer irradiation time of the solution early crystallization in the drops occurs. A saturated water solution of KCl was irradiated with the diffractometer DRON-3M (Russian device) and this had a great influence on the two-step processes of crystallization. The ionization of the solution by soft X-rays can produce ions, metastable radicals in water, excited crystals' seeds and vacancies in growing crystals by Auger's effect. The X-rays generate a very fast crystallization in the drying drop.

TH-AB-209-07: High Resolution X-Ray-Induced Acoustic Computed Tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiang, L; Tang, S; Ahmad, M

Purpose: X-ray radiographic absorption imaging is an invaluable tool in medical diagnostics, biology and materials science. However, the use of conventional CT is limited by two factors: the detection sensitivity to weak absorption material and the radiation dose from CT scanning. The purpose of this study is to explore X-ray induced acoustic computed tomography (XACT), a new imaging modality, which combines X-ray absorption contrast and high ultrasonic resolution to address these challenges. Methods: First, theoretical models was built to analyze the XACT sensitivity to X-ray absorption and calculate the minimal radiation dose in XACT imaging. Then, an XACT system comprisedmore » of an ultrashort X-ray pulse, a low noise ultrasound detector and a signal acquisition system was built to evaluate the X-ray induced acoustic signal generation. A piece of chicken bone and a phantom with two golden fiducial markers were exposed to 270 kVp X-ray source with 60 ns exposure time, and the X-ray induced acoustic signal was received by a 2.25MHz ultrasound transducer in 200 positions. XACT images were reconstructed by a filtered back-projection algorithm. Results: The theoretical analysis shows that X-ray induced acoustic signals have 100% relative sensitivity to X-ray absorption, but not to X-ray scattering. Applying this innovative technology to breast imaging, we can reduce radiation dose by a factor of 50 compared with newly FDA approved breast CT. The reconstructed images of chicken bone and golden fiducial marker phantom reveal that the spatial resolution of the built XACT system is 350µm. Conclusion: In XACT, the imaging sensitivity to X-ray absorption is improved and the imaging dose is dramatically reduced by using ultrashort pulsed X-ray. Taking advantage of the high ultrasonic resolution, we can also perform 3D imaging with a single X-ray pulse. This new modality has the potential to revolutionize x-ray imaging applications in medicine and biology.« less

Synthesis of nanoparticles through x-ray radiolysis using synchrotron radiation

NASA Astrophysics Data System (ADS)

Yamaguchi, A.; Okada, I.; Fukuoka, T.; Ishihara, M.; Sakurai, I.; Utsumi, Y.

2016-09-01

The synthesis and deposition of nanoparticles consisting of Cu and Au in a CuSO4 solution with some kinds of alcohol and electroplating solution containing gold (I) trisodium disulphite under synchrotron X-ray radiation was investigated. The functional group of alcohol plays an important in nucleation, growth and aggregation process of copper and cupric oxide particles. We found that the laboratory X-ray source also enables us to synthesize the NPs from the metallic solution. As increasing X-ray exposure time, the full length at half width of particle size distribution is broader and higher-order nanostructure containing NPs clusters is formed. The surface-enhanced Raman scattering (SERS) of 4, 4'-bipyridine (4bpy) in aqueous solution was measured using higher-order nanostructure immobilized on silicon substrates under systematically-varied X-ray exposure. This demonstration provide a clue to develop a three-dimensional printing and sensor for environmental analyses and molecular detection through simple SERS measurements.

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

PubMed Central

Anfinrud, Philip

2010-01-01

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 Å-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 Å), 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 Å3 volume expansion of the protein. The ensuing conformational relaxation causes the protein to contract to a volume ∼2 Å3 larger than MbCO within ∼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. PMID:20406909

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

PubMed

Cho, Hyun Sun; Dashdorj, Naranbaatar; Schotte, Friedrich; Graber, Timothy; Henning, Robert; Anfinrud, Philip

2010-04-20

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 A(-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 A), 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 A(3) volume expansion of the protein. The ensuing conformational relaxation causes the protein to contract to a volume approximately 2 A(3) larger than MbCO within approximately 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.

Development of a micro-XRF system for biological samples based on proton-induced quasimonochromatic X-rays

NASA Astrophysics Data System (ADS)

Ploykrachang, K.; Hasegawa, J.; Kondo, K.; Fukuda, H.; Oguri, Y.

2014-07-01

We have developed a micro-XRF system based on a proton-induced quasimonochromatic X-ray (QMXR) microbeam for in vivo measurement of biological samples. A 2.5-MeV proton beam impinged normally on a Cu foil target that was slightly thicker than the proton range. The emitted QMXR behind the Cu target was focused with a polycapillary X-ray half lens. For application to analysis of wet or aquatic samples, we prepared a QMXR beam with an incident angle of 45° with respect to the horizontal plane by using a dipole magnet in order to bend the primary proton beam downward by 45°. The focal spot size of the QMXR microbeam on a horizontal sample surface was evaluated to be 250 × 350 μm by a wire scanning method. A microscope camera with a long working distance was installed perpendicular to the sample surface to identify the analyzed position on the sample. The fluorescent radiation from the sample was collected by a Si-PIN photodiode X-ray detector. Using the setup above, we were able to successfully measure the accumulation and distribution of Co in the leaves of a free-floating aquatic plant on a dilute Co solution surface.

Berberine potentizes apoptosis induced by X-rays irradiation probably through modulation of gap junctions.

PubMed

Liu, Bing; Wang, Qin; Yuan, Dong-dong; Hong, Xiao-ting; Tao, Liang

2011-04-01

Clinical combination of some traditional Chinese medical herbs, including berberine, with irradiation is demonstrated to improve efficacy of tumor radiotherapy, yet the mechanisms for such effect remain largely unknown. The present study investigated the effect of berberine on apoptosis induced by X-rays irradiation and the relation between this effect and gap junction intercellular communication (GJIC). The role of gap junctions in the modulation of X-rays irradiation-induced apoptosis was explored by manipulation of connexin (Cx) expression, and gap junction function, using oleamide, a GJIC inhibitor, and berberine. In transfected HeLa cells, Cx32 expression increased apoptosis induced by X-rays irradiation, while inhibition of gap junction by oleamide reduced the irradiation responses, indicating the dependence of X-rays irradiation-induced apoptosis on GJIC. Berberine, at the concentrations without cytotoxicity, enhanced apoptosis induced by irradiation only in the presence of functional gap junctions. These results suggest that berberine potentizes cell apoptosis induced by X-rays irradiation, probably through enhancement of gap junction activity.

X-ray induced dimerization of cinnamic acid: Time-resolved inelastic X-ray scattering study

NASA Astrophysics Data System (ADS)

Inkinen, Juho; Niskanen, Johannes; Talka, Tuomas; Sahle, Christoph J.; Müller, Harald; Khriachtchev, Leonid; Hashemi, Javad; Akbari, Ali; Hakala, Mikko; Huotari, Simo

2015-11-01

A classic example of solid-state topochemical reactions is the ultraviolet-light induced photodimerization of α-trans-cinnamic acid (CA). Here, we report the first observation of an X-ray-induced dimerization of CA and monitor it in situ using nonresonant inelastic X-ray scattering spectroscopy (NRIXS). The time-evolution of the carbon core-electron excitation spectra shows the effects of two X-ray induced reactions: dimerization on a short time-scale and disintegration on a long time-scale. We used spectrum simulations of CA and its dimerization product, α-truxillic acid (TA), to gain insight into the dimerization effects. From the time-resolved spectra, we extracted component spectra and time-dependent weights corresponding to CA and TA. The results suggest that the X-ray induced dimerization proceeds homogeneously in contrast to the dimerization induced by ultraviolet light. We also utilized the ability of NRIXS for direct tomography with chemical-bond contrast to image the spatial progress of the reactions in the sample crystal. Our work paves the way for other time-resolved studies on chemical reactions using inelastic X-ray scattering.

X-ray induced dimerization of cinnamic acid: Time-resolved inelastic X-ray scattering study

PubMed Central

Inkinen, Juho; Niskanen, Johannes; Talka, Tuomas; Sahle, Christoph J.; Müller, Harald; Khriachtchev, Leonid; Hashemi, Javad; Akbari, Ali; Hakala, Mikko; Huotari, Simo

2015-01-01

A classic example of solid-state topochemical reactions is the ultraviolet-light induced photodimerization of α-trans-cinnamic acid (CA). Here, we report the first observation of an X-ray-induced dimerization of CA and monitor it in situ using nonresonant inelastic X-ray scattering spectroscopy (NRIXS). The time-evolution of the carbon core-electron excitation spectra shows the effects of two X-ray induced reactions: dimerization on a short time-scale and disintegration on a long time-scale. We used spectrum simulations of CA and its dimerization product, α-truxillic acid (TA), to gain insight into the dimerization effects. From the time-resolved spectra, we extracted component spectra and time-dependent weights corresponding to CA and TA. The results suggest that the X-ray induced dimerization proceeds homogeneously in contrast to the dimerization induced by ultraviolet light. We also utilized the ability of NRIXS for direct tomography with chemical-bond contrast to image the spatial progress of the reactions in the sample crystal. Our work paves the way for other time-resolved studies on chemical reactions using inelastic X-ray scattering. PMID:26568420

Ultrafast myoglobin structural dynamics observed with an X-ray free-electron laser

DOE PAGES

Levantino, Matteo; Schirò, Giorgio; Lemke, Henrik Till; ...

2015-04-02

Light absorption can trigger biologically relevant protein conformational changes. The light induced structural rearrangement at the level of a photoexcited chromophore is known to occur in the femtosecond timescale and is expected to propagate through the protein as a quake-like intramolecular motion. Here we report direct experimental evidence of such ‘proteinquake’ observed in myoglobin through femtosecond X-ray solution scattering measurements performed at the Linac Coherent Light Source X-ray free-electron laser. An ultrafast increase of myoglobin radius of gyration occurs within 1 picosecond and is followed by a delayed protein expansion. As the system approaches equilibrium it undergoes damped oscillations withmore » a ~3.6-picosecond time period. Our results unambiguously show how initially localized chemical changes can propagate at the level of the global protein conformation in the picosecond timescale.« less

X-ray Scattering Combined with Coordinate-Based Analyses for Applications in Natural and Artificial Photosynthesis

PubMed Central

Tiede, David M.; Mardis, Kristy L.; Zuo, Xiaobing

2009-01-01

Advances in x-ray light sources and detectors have created opportunities for advancing our understanding of structure and structural dynamics for supramolecular assemblies in solution by combining x-ray scattering measurement with coordinate-based modeling methods. In this review the foundations for x-ray scattering are discussed and illustrated with selected examples demonstrating the ability to correlate solution x-ray scattering measurements to molecular structure, conformation, and dynamics. These approaches are anticipated to have a broad range of applications in natural and artificial photosynthesis by offering possibilities for structure resolution for dynamic supramolecular assemblies in solution that can not be fully addressed with crystallographic techniques, and for resolving fundamental mechanisms for solar energy conversion by mapping out structure in light-excited reaction states. PMID:19636808

Biocompatible Materials Based on Self-Assembling Peptides on Ti25Nb10Zr Alloy: Molecular Structure and Organization Investigated by Synchrotron Radiation Induced Techniques.

PubMed

Secchi, Valeria; Franchi, Stefano; Santi, Marta; Vladescu, Alina; Braic, Mariana; Skála, Tomáš; Nováková, Jaroslava; Dettin, Monica; Zamuner, Annj; Iucci, Giovanna; Battocchio, Chiara

2018-03-07

In this work, we applied advanced Synchrotron Radiation (SR) induced techniques to the study of the chemisorption of the Self Assembling Peptide EAbuK16, i.e., H-Abu-Glu-Abu-Glu-Abu-Lys-Abu-Lys-Abu-Glu-Abu-Glu-Abu-Lys-Abu-Lys-NH₂ that is able to spontaneously aggregate in anti-parallel β-sheet conformation, onto annealed Ti25Nb10Zr alloy surfaces. This synthetic amphiphilic oligopeptide is a good candidate to mimic extracellular matrix for bone prosthesis, since its β-sheets stack onto each other in a multilayer oriented nanostructure with internal pores of 5-200 nm size. To prepare the biomimetic material, Ti25Nb10Zr discs were treated with aqueous solutions of EAbuK16 at different pH values. Here we present the results achieved by performing SR-induced X-ray Photoelectron Spectroscopy (SR-XPS), angle-dependent Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, FESEM and AFM imaging on Ti25Nb10Zr discs after incubation with self-assembling peptide solution at five different pH values, selected deliberately to investigate the best conditions for peptide immobilization.

Induced synthesis of toroid-like lead sulfide nanocomposites in ethanol solution through a protein templating route

NASA Astrophysics Data System (ADS)

Zhang, Li; Qin, Dezhi; Yang, Guangrui; Du, Xian; Zhang, Qiuxia; Li, Feng

2015-09-01

The toroid-like PbS nanocrystals have been prepared in zein ethanol solution based on self-assembly template of protein molecules. From transmission electron microscopy observation, the obtained samples were monodispersed with an average size of about 47 nm. The chemical composition and crystal structure of nanocomposites were determined by X-ray diffraction and energy-dispersive X-ray spectrum measurements. The interaction between PbS and zein was investigated through Fourier transform infrared, photoluminescence, circular dichroism (CD) spectra, and thermogravimetric analysis. The PbS nanocrystals could react with nitrogen and oxygen atoms of zein molecules through coordination and electrostatic force. The CD spectra results suggested that PbS nanocrystals induced the conformational transition of protein from α-helix to β-sheet and then self-assembled into ring or toroid nanostructure. The quenching of zein fluorescence induced by PbS nanocrystals also showed the change in the chemical microenvironments of the fluorescent amino acid residues in the protein structure. The key step of this facile, biomimetic route was the formation of self-assembly nanostructure of zein, which could regulate the nucleation and growth of toroid-like PbS nanocrystals.

Luminescent properties under X-ray excitation of Ba(1-x)PbxWO4 disordered solid solution

NASA Astrophysics Data System (ADS)

Bakiz, B.; Hallaoui, A.; Taoufyq, A.; Benlhachemi, A.; Guinneton, F.; Villain, S.; Ezahri, M.; Valmalette, J.-C.; Arab, M.; Gavarri, J.-R.

2018-02-01

A series of polycrystalline barium-lead tungstate Ba1-xPbxWO4 with 0 ≤ x ≤ 1 was synthesized using a classical solid-state method with thermal treatment at 1000 °C. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Raman (FT-Raman) spectroscopy. X-ray diffraction profile analyses were performed using Rietveld method. These materials crystallized in the scheelite tetragonal structure and behaved as quasi ideal solid solution. Raman spectroscopy confirmed the formation of the solid solution. Structural distortions were evidenced in X-ray diffraction profiles and in vibration Raman spectra. The scanning electron microscopy experiments showed large and rounded irregular grains. Luminescence experiments were performed under X-ray excitation. The luminescence emission profiles have been interpreted in terms of four Gaussian components, with a major contribution of blue emission. The integrated intensity of luminescence reached a maximum value in the composition range x = 0.3-0.6, in relation with distortions of crystal lattice.

Kinetic Modeling of the X-ray-induced Damage to a Metalloprotein

PubMed Central

Davis, Katherine M.; Kosheleva, Irina; Henning, Robert W.; Seidler, Gerald T.; Pushkar, Yulia

2013-01-01

It is well known that biological samples undergo x-ray-induced degradation. One of the fastest occurring x-ray-induced processes involves redox modifications (reduction or oxidation) of redox-active cofactors in proteins. Here we analyze room temperature data on the photoreduction of Mn ions in the oxygen evolving complex (OEC) of photosystem II, one of the most radiation damage sensitive proteins and a key constituent of natural photosynthesis in plants, green algae and cyanobacteria. Time-resolved x-ray emission spectroscopy with wavelength-dispersive detection was used to collect data on the progression of x-ray-induced damage. A kinetic model was developed to fit experimental results, and the rate constant for the reduction of OEC MnIII/IV ions by solvated electrons was determined. From this model, the possible kinetics of x-ray-induced damage at variety of experimental conditions, such as different rates of dose deposition as well as different excitation wavelengths, can be inferred. We observed a trend of increasing dosage threshold prior to the onset of x-ray-induced damage with increasing rates of damage deposition. This trend suggests that experimentation with higher rates of dose deposition is beneficial for measurements of biological samples sensitive to radiation damage, particularly at pink beam and x-ray FEL sources. PMID:23815809

Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics

PubMed Central

Picón, A.; Lehmann, C. S.; Bostedt, C.; Rudenko, A.; Marinelli, A.; Osipov, T.; Rolles, D.; Berrah, N.; Bomme, C.; Bucher, M.; Doumy, G.; Erk, B.; Ferguson, K. R.; Gorkhover, T.; Ho, P. J.; Kanter, E. P.; Krässig, B.; Krzywinski, J.; Lutman, A. A.; March, A. M.; Moonshiram, D.; Ray, D.; Young, L.; Pratt, S. T.; Southworth, S. H.

2016-01-01

New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Particularly, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. Here we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ions during the fragmentation of XeF2 molecules following X-ray absorption at the Xe site. PMID:27212390

Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics.

PubMed

Picón, A; Lehmann, C S; Bostedt, C; Rudenko, A; Marinelli, A; Osipov, T; Rolles, D; Berrah, N; Bomme, C; Bucher, M; Doumy, G; Erk, B; Ferguson, K R; Gorkhover, T; Ho, P J; Kanter, E P; Krässig, B; Krzywinski, J; Lutman, A A; March, A M; Moonshiram, D; Ray, D; Young, L; Pratt, S T; Southworth, S H

2016-05-23

New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Particularly, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. Here we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ions during the fragmentation of XeF2 molecules following X-ray absorption at the Xe site.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Picón, A.; Lehmann, C. S.; Bostedt, C.

New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Specifically, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. In this paper, we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ionsmore » during the fragmentation of XeF 2 molecules following X-ray absorption at the Xe site.« less

Energy dispersive X-ray analyses of organelles of NaCI-treated maize root cells

NASA Astrophysics Data System (ADS)

Stelzer, Ralf

1984-04-01

NaCl sensitive plants of Zea mays cv. ADOUR were grown in nutrient solutions with or without NaCl. Frozen, hydrated root-tip tissues were investigated by means of an ETEC scanning electron microscope fitted with a KEVEX energy dispersive X-ray analyser. Morphological details of the gently etched but non-coated surface of the cross fractured specimen were easy to identify and to analyse using an electron beam with a low intensity at 10 kV. X-ray data obtained from cell compartments and organelles as nuclei, nucleoli and mitochondria within individual cells establish typical X-ray spectra. Comparisons of these spectra support the hypothesis that Na + ions are predominantly localized in vacuoles and also to a lesser extent in the cytoplasm, e.g. in small vesicles, but not in other cell organelles. Furthermore the analysed cell compartments show differences in the distribution of Mg, P, S, Cl, K and Ca effected by the addition of NaCl to the growth medium. The X-ray data are discussed in relation to the physiological meaning of a NaCl induced redistribution of elements within individual maize root cells.

X-ray-induced photo-chemistry and X-ray absorption spectroscopy of biological samples

PubMed Central

George, Graham N.; Pickering, Ingrid J.; Pushie, M. Jake; Nienaber, Kurt; Hackett, Mark J.; Ascone, Isabella; Hedman, Britt; Hodgson, Keith O.; Aitken, Jade B.; Levina, Aviva; Glover, Christopher; Lay, Peter A.

2012-01-01

As synchrotron light sources and optics deliver greater photon flux on samples, X-ray-induced photo-chemistry is increasingly encountered in X-ray absorption spectroscopy (XAS) experiments. The resulting problems are particularly pronounced for biological XAS experiments. This is because biological samples are very often quite dilute and therefore require signal averaging to achieve adequate signal-to-noise ratios, with correspondingly greater exposures to the X-ray beam. This paper reviews the origins of photo-reduction and photo-oxidation, the impact that they can have on active site structure, and the methods that can be used to provide relief from X-ray-induced photo-chemical artifacts. PMID:23093745

Program for Research on Conducting Polymers

DTIC Science & Technology

1991-07-17

Excitations in Polyaniline (Synthetic Metals). 29. Transient Photoconductivity in Oriented Irans-Polyacetylene Prepared by the Naarmann-Theophilou Method...State Physics). 33. X-Ray Scattering from Crystalline Polyaniline (Polymer Commun.). 34. Photogenerated Carriers in La2CuO4,YBa2Cu3O7-8 and TI2Ba2Ca...1- x)GdxCu208: Polarizability-Induced Pairing of Polarons (Synthetic Metals). 35. Spectroscopic Studies of Polyaniline in Solution and in Spin-Cast

Portable TXRF Spectrometer with 10{sup -11}g Detection Limit and Portable XRF Spectromicroscope with Sub-mm Spatial Resolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kunimura, Shinsuke; Hatakeyama, So; Sasaki, Nobuharu

A portable total reflection X-ray fluorescence (TXRF) spectrometer that we have developed is applied to trace elemental analysis of water solutions. Although a 5 W X-ray tube is used in the portable TXRF spectrometer, detection limits of several ppb are achieved for 3d transition metal elements and trace elements in a leaching solution of soils, a leaching solution of solder, and alcoholic beverages are detected. Portable X-ray fluorescence (XRF) spectromicroscopes with a 1 W X-ray tube and an 8 W X-ray tube are also presented. Using the portable XRF spectromicroscope with the 1 W X-ray tube, 93 ppm of Crmore » is detected with an about 700 {mu}m spatial resolution. Spatially resolved elemental analysis of a mug painted with blue, red, green, and white is performed using the two portable spectromicroscopes, and the difference in elemental composition at each paint is detected.« less

Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics

DOE PAGES

Picón, A.; Lehmann, C. S.; Bostedt, C.; ...

2016-05-23

New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Specifically, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. In this paper, we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ionsmore » during the fragmentation of XeF 2 molecules following X-ray absorption at the Xe site.« less

Instrumentation on Multi-Scaled Scattering of Bio-Macromolecular Solutions

PubMed Central

Chu, Benjamin; Fang, Dufei; Mao, Yimin

2015-01-01

The design, construction and initial tests on a combined laser light scattering and synchrotron X-ray scattering instrument can cover studies of length scales from atomic sizes in Angstroms to microns and dynamics from microseconds to seconds are presented. In addition to static light scattering (SLS), dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD), the light scattering instrument is being developed to carry out studies in mildly turbid solutions, in the presence of multiple scattering. Three-dimensional photon cross correlation function (3D-PCCF) measurements have been introduced to couple with synchrotron X-ray scattering to study the structure, size and dynamics of macromolecules in solution. PMID:25946340

Imaging local electric fields produced upon synchrotron X-ray exposure

DOE PAGES

Dettmar, Christopher M.; Newman, Justin A.; Toth, Scott J.; ...

2014-12-31

Electron–hole separation following hard X-ray absorption during diffraction analysis of soft materials under cryogenic conditions produces substantial local electric fields visualizable by second harmonic generation (SHG) microscopy. Monte Carlo simulations of X-ray photoelectron trajectories suggest the formation of substantial local electric fields in the regions adjacent to those exposed to X-rays, indicating a possible electric-field–induced SHG (EFISH) mechanism for generating the observed signal. In studies of amorphous vitreous solvents, analysis of the SHG spatial profiles following X-ray microbeam exposure was consistent with an EFISH mechanism. Within protein crystals, exposure to 12-keV (1.033-Å) X-rays resulted in increased SHG in the regionmore » extending ~3 μm beyond the borders of the X-ray beam. Moderate X-ray exposures typical of those used for crystal centering by raster scanning through an X-ray beam were sufficient to produce static electric fields easily detectable by SHG. The X-ray–induced SHG activity was observed with no measurable loss for longer than 2 wk while maintained under cryogenic conditions, but disappeared if annealed to room temperature for a few seconds. In conclusion, these results provide direct experimental observables capable of validating simulations of X-ray–induced damage within soft materials. Additionally, X-ray–induced local fields may potentially impact diffraction resolution through localized piezoelectric distortions of the lattice.« less

The GALAXIE all-optical FEL project

NASA Astrophysics Data System (ADS)

Rosenzweig, J. B.; Arab, E.; Andonian, G.; Cahill, A.; Fitzmorris, K.; Fukusawa, A.; Hoang, P.; Jovanovic, I.; Marcus, G.; Marinelli, A.; Murokh, A.; Musumeci, P.; Naranjo, B.; O'Shea, B.; O'Shea, F.; Ovodenko, A.; Pogorelsky, I.; Putterman, S.; Roberts, K.; Shumail, M.; Tantawi, S.; Valloni, A.; Yakimenko, V.; Xu, G.

2012-12-01

We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 μm laser development, ultra-high brighness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.

X-ray based extensometry

NASA Technical Reports Server (NTRS)

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

1988-01-01

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

Effect of aspirin on chromosome aberration and DNA damage induced by X-rays in mice

NASA Astrophysics Data System (ADS)

Niikawa, M.; Chuuriki, K.; Shibuya, K.; Seo, M.; Nagase, H.

In order to reveal the anticlastogenic potency of aspirin, we evaluated the suppressive ability of aspirin on chromosome aberrations induced by X-ray. Aspirin at doses of 0.5, 5 and 50 mg/kg was administrated intraperitoneally or orally at 0.5 h after or before the X-ray irradiation. The anticlastogenic activity of aspirin on chromosome aberrations induced by X-ray was determined in the mouse micronucleus test and alkaline single cell gel electrophoresis (SCG) assay in vivo. The frequency by polychromatic erythrocytes with micronuclei (MNPCEs) was decreased by about 19-61% at 0.5 h after and about 23-62% at 0.5 h before the X-ray irradiation. DNA damage by X-ray was significantly decreased by oral administration of aspirin at 0.5 h after or before the X-ray irradiation for the SCG assay. We consider aspirin can be used as preventive agents against exposure of X-ray.

The Columbia University proton-induced soft x-ray microbeam.

PubMed

Harken, Andrew D; Randers-Pehrson, Gerhard; Johnson, Gary W; Brenner, David J

2011-09-15

A soft x-ray microbeam using proton-induced x-ray emission (PIXE) of characteristic titanium (K(α) 4.5 keV) as the x-ray source has been developed at the Radiological Research Accelerator Facility (RARAF) at Columbia University. The proton beam is focused to a 120 μm × 50 μm spot on the titanium target using an electrostatic quadrupole quadruplet previously used for the charged particle microbeam studies at RARAF. The proton induced x-rays from this spot project a 50 μm round x-ray generation spot into the vertical direction. The x-rays are focused to a spot size of 5 μm in diameter using a Fresnel zone plate. The x-rays have an attenuation length of (1/e length of ~145 μm) allowing more consistent dose delivery across the depth of a single cell layer and penetration into tissue samples than previous ultra soft x-ray systems. The irradiation end station is based on our previous design to allow quick comparison to charged particle experiments and for mixed irradiation experiments.

Control of Porosity in Ladder Polymers by Solvent-induced Aggregation

NASA Astrophysics Data System (ADS)

Brady, Michael; Gamo, Eri; Wang, Cheng; Xia, Yan

Porous polymers hold promise as materials for gas absorption, membranes, and organic electronics. In all of these applications, attaining in-plane ordering of backbones and thus porous free volume impacts the ability to adsorb gas, selectively filter molecules, and conduct charges. In this work, hard and soft x-ray scattering and soft x-ray spectroscopy are of focus to study the pore structure, induced by the solution-driven aggregation of ladder polymer thin films made of LP-1 and LP-2. Using GISAXS and AFM it is shown that thermal annealing drives the growth of crystallites in thin films. Due to the completely sp2nature of the ladder polymer backbones, it is expected that backbones are extremely stiff and thus preventing them from packing once left in a metastable state following casting. Therefore, the combination of GIWAXS and GISAXS will be shown to be critical in correctly understanding how pores develop in this 700 m2/g sorbent (N2). Finally, application in CO2/N2 separation membranes towards carbon sequestration will be presented that show gas selectivity is achieved through heteroatom incorporation and polymer blending. In this talk, focus will be placed on state-of-the-art x-ray scattering and spectroscopy, highlighting the importance of chemically sensitive structural information enabled by the combination of spectroscopy and scattering at play with the use of resonant soft x-rays.

Air-stable, solution-processed oxide p-n heterojunction ultraviolet photodetector.

PubMed

Kim, Do Young; Ryu, Jiho; Manders, Jesse; Lee, Jaewoong; So, Franky

2014-02-12

Air-stable solution processed all-inorganic p-n heterojunction ultraviolet photodetector is fabricated with a high gain (EQE, 25 300%). Solution-processed NiO and ZnO films are used as p-type and n-type ultraviolet sensitizing materials, respectively. The high gain in the detector is due to the interfacial trap-induced charge injection that occurs at the ITO/NiO interface by photogenerated holes trapped in the NiO film. The gain of the detector is controlled by the post-annealing temperature of the solution-processed NiO films, which are studied by X-ray photoelectron spectroscopy (XPS).

Antimutagenic property of a Chinese herb

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hongen Zhang; Te-Hsiu Ma; Byeong-Seon Jeong

1994-12-31

The root extracts of a Chinese herb, Polygonum multiflorum Thunb, has been used as internal medicine to improve liver and kidney functions for centuries. The antimutagenic property of this drug was evaluated with the Tradescantia-micronucleus (Trad-MCN) assay in this study. The Trad-MCN bioassay is a well-established test for chromosome damage induced by physical or chemical agents in terms of micronuclei (MCN) frequency. Inflorescences of the Tradescantia plant cuttings were first exposed to 35 R soft X-rays (80 Kv, 5 ma, 1 mm Al filter, dose rate around 50 R/min) and followed by drug treatments at 1%, 3% and 6% concentrationsmore » of the aqueous solution for a total of 24 hr recovery period. The positive (X-rays), negative (nutrient solution) and drug control (3% drug solution) groups were maintained in each of the three series of repeated experiments. Flower buds of the treated and control groups were fixed in aceto-alcohol (1:3 ratio) for preparation of slides to score MCN frequencies in the early tetrads of the meiotic pollen mother cells. The mean MCN frequencies (MCN/100 tetrads + SD) of the positive control (X-irradiated) was 26.67 + 9.62; the negative control was 2.92 + 1.90; the drug control was 2.06 + 1.50 and the 35 R X-ray/6% drug treated was 18.75 + 6.54. A 30% reduction of chromosome damage was observed. Antimutagenic effects were relatively lower at lower concentrations. This antimutagenic effect could be the results of the meiotic inhibition, DNA repair or radical elimination from the X-irradiation plant cells.« less

Polyaniline (PANI) modified bentonite by plasma technique for U(VI) removal from aqueous solution

NASA Astrophysics Data System (ADS)

Liu, Xinghao; Cheng, Cheng; Xiao, Chengjian; Shao, Dadong; Xu, Zimu; Wang, Jiaquan; Hu, Shuheng; Li, Xiaolong; Wang, Weijuan

2017-07-01

Polyaniline (PANI) modified bentonite (PANI/bentonie) was synthesized by plasma induced polymerization of aniline on bentonite surface, and applied to uptake of uranium(VI) ions from aqueous solution. The as-synthesized PANI/bentonie was characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). Batch adsorption technique was utilized to investigate the adsorption of U(VI) on bentonite and PANI/bentonite. The adsorption of U(VI) (10 mg/L) on PANI/bentonite surface is fairly depend on solution pH, ionic strength, and temperature in solution. The modified PANI on PANI/bentonite surface significantly enhances its adsorption capability for U(VI). The presence of humic acid (HA) can sound enhance U(VI) adsorption on PANI/bentonite at pH < 6.5 because of the strong complexation, and inhibits U(VI) adsorption at pH > 6.5. According to the thermodynamic parameters, the adsorption of U(VI) on PANI/bentonite surface is a spontaneous and endothermic process. The results highlight the application of PANI/bentonite composites as candidate material for the uptake of trace U(VI) from aqueous solution.

Pump–probe spectrometer for measuring x-ray induced strain

DOE PAGES

Loether, A.; Adams, B. W.; DiCharia, A.; ...

2016-04-20

A hard x-ray pump–probe spectrometer using a multi-crystal Bragg reflector is demonstrated at a third generation synchrotron source. This device derives both broadband pump and monochromatic probe pulses directly from a single intense, broadband x-ray pulse centered at 8.767 keV. In conclusion, we present a proof-of-concept experiment which directly measures x-ray induced crystalline lattice strain.

THE RADIATION-INDUCED POLYMERIZATION OF ISOBUTENE: A LIQUID PHASE IONIC REACTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collinson, E.; Dainton, F.S.; Gillis, H.A.

1959-06-01

New evidence is presented in support of the suggestion that the gamma - ray-induced polymerization of liquid isobutene at -78 deg C proceeds solely by a cationic mechanism. Attempts to polymerize isobutene at -78 deg C with free radicals from the photolysis of diacetyl, benzoin and benzil were unsuccessful but the benzil solution irradiated with ultraviolet light at 77 deg K was shown by electron spin resonance measurements to give rise to radicals from the isobutene. Isobutene irradiated in the pure state at a gamma -ray dose rate of 7 x 10/sup 17/ e.v. ml/sup -1/ min/sup -1/ polymerized withmore » G(-C/sub 4/H/sub 8/) = 3.0 plus or minus 1.7 x 10/sup 2/. Solutions of FeCl/sub 3/, DPPH, benzoquinone and iodine in isobutene were also irradiated with gamma -rays. Of these solutes, only benzoquinone reduced the polymerization rate to zero, and DPPH had no significant effect. The effects of FeCl/sub 3/ and I/2 on the polymerization were complicated by other factors. The measured yields of conversion of the solutes after irradiation were G(-DPPH) =3.7 plus or minus 0.2, G(Fe(II)) = 3.0 plus or minus 0.5 and G(-Q) = 1.5 plus or minus 0.2. The electron spin resonance spectrum of isobutene irradiated with gamma -rays at 77 deg K showed the presence of H atoms which disappeared rapidly, and a more stable radical, the spectrum of which consisted of 6 peaks having an over-all spacing of 158 gauss at the operating frequency of 9400 Mc sec./sup -1/. The same six peak pattern was obtained from cyclopropane irradiated with gamma rays at 77 deg K and from a solution of benzil in isoDutene irradiated with ultraviolet light at 77 deg K. It is concluded that the radical responsible for this spectrum is either the cyclopropyl radical or the methyl substituted allyl radical, the latter being the less likely. The most likely initiating ion is considered to be (CH/sub 3/)/sub 3/C/sup +/, and a mechanism consistent with the available data is proposed. (auth)« less

Biocompatible Materials Based on Self-Assembling Peptides on Ti25Nb10Zr Alloy: Molecular Structure and Organization Investigated by Synchrotron Radiation Induced Techniques

PubMed Central

Franchi, Stefano; Braic, Mariana; Skála, Tomáš; Nováková, Jaroslava; Zamuner, Annj

2018-01-01

In this work, we applied advanced Synchrotron Radiation (SR) induced techniques to the study of the chemisorption of the Self Assembling Peptide EAbuK16, i.e., H-Abu-Glu-Abu-Glu-Abu-Lys-Abu-Lys-Abu-Glu-Abu-Glu-Abu-Lys-Abu-Lys-NH2 that is able to spontaneously aggregate in anti-parallel β-sheet conformation, onto annealed Ti25Nb10Zr alloy surfaces. This synthetic amphiphilic oligopeptide is a good candidate to mimic extracellular matrix for bone prosthesis, since its β-sheets stack onto each other in a multilayer oriented nanostructure with internal pores of 5–200 nm size. To prepare the biomimetic material, Ti25Nb10Zr discs were treated with aqueous solutions of EAbuK16 at different pH values. Here we present the results achieved by performing SR-induced X-ray Photoelectron Spectroscopy (SR-XPS), angle-dependent Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, FESEM and AFM imaging on Ti25Nb10Zr discs after incubation with self-assembling peptide solution at five different pH values, selected deliberately to investigate the best conditions for peptide immobilization. PMID:29518968

Aplanatic Three-Mirror Objective for High-Magnification Soft X-Ray Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toyoda, M.; Jinno, T.; Yanagihara, M.

2011-09-09

An innovative solution for high-magnification microscopy, based on attaching afocal optics for focal length reduction, is proposed. The solution, consisting of three spherical mirrors, allows one to enhance a magnification of a laboratory based soft x-ray microscope over 1000x, where movies with diffraction-limited resolution can be observed with an x-ray CCD. The design example, having a numerical aperture of 0.25, was successfully demonstrated both a high magnification and a large field of view.

Incorporation of Cadmium and Nickel into Ferrite Spinel Solid Solution: X-ray Diffraction and X-ray Absorption Fine Structure Analyses.

PubMed

Su, Minhua; Liao, Changzhong; Chan, Tingshan; Shih, Kaimin; Xiao, Tangfu; Chen, Diyun; Kong, Lingjun; Song, Gang

2018-01-16

The feasibility of incorporating Cd and Ni in hematite was studied by investigating the interaction mechanism for the formation of Cd x Ni 1-x Fe 2 O 4 solid solutions (CNFs) from CdO, NiO, and α-Fe 2 O 3 . X-ray diffraction results showed that the CNFs crystallized into spinel structures with increasing lattice parameters as the Cd content in the precursors was increased. Cd 2+ ions were found to occupy the tetrahedral sites, as evidenced by Rietveld refinement and extended X-ray absorption fine structure analyses. The incorporation of Cd and Ni into ferrite spinel solid solution strongly relied on the processing parameters. The incorporation of Cd and Ni into the CNFs was greater at high x values (0.7 < x ≤ 1.0) than at low x values (0.0 ≤ x ≤ 0.7). A feasible treatment technique based on the investigated mechanism of CNF formation was developed, involving thermal treatment of waste sludge containing Cd and Ni. Both of these metals in the waste sludge were successfully incorporated into a ferrite spinel solid solution, and the concentrations of leached Cd and Ni from this solid solution were substantially reduced, stabilizing at low levels. This research offers a highly promising approach for treating the Cd and Ni content frequently encountered in electronic waste and its treatment residues.

Radiation-induced segregation in model alloys

NASA Astrophysics Data System (ADS)

Ezawa, T.; Wakai, E.; Oshima, R.

2000-12-01

The dependence of the size factor of solutes on radiation-induced segregation (RIS) was studied. Ni-Si, Ni-Co, Ni-Cu, Ni-Mn, Ni-Pd, and Ni-Nb binary solid solution alloys were irradiated with electrons in a high voltage electron microscope at the same irradiation conditions. A focused beam and a grain boundary were utilized to generate a flow of point defects to cause RIS. From the concentration profile obtained by an energy dispersive X-ray analysis, the amount of RIS was calculated. The amount of RIS decreased as the size of the solute increased up to about 10%. However, as the size increased further, the amount of RIS increased. This result shows that RIS is not simply determined by the size effect rule.

X-ray Irradiation Induced Reversible Resistance Change in Pt/TiO 2 /Pt Cells

DOE PAGES

Chang, Seo Hyoung; Kim, Jungho; Phatak, Charudatta; ...

2014-02-25

The interaction between X-rays and matter is an intriguing topic for both fundamental science and possible applications. In particular, synchrotron-based brilliant X-ray beams have been used as a powerful diagnostic tool to unveil nanoscale phenomena in functional materials. But, it has not been widely investigated how functional materials respond to the brilliant X-rays. Here, we report the X-ray-induced reversible resistance change in 40-nm-thick TiO 2 films sandwiched by Pt top and bottom electrodes, and propose the physical mechanism behind the emergent phenomenon. Our findings indicate that there exists a photovoltaic-like effect, which modulates the resistance reversibly by a few ordersmore » of magnitude, depending on the intensity of impinging X-rays. Furthermore, we found that this effect, combined with the X-ray irradiation induced phase transition confirmed by transmission electron microscopy, triggers a nonvolatile reversible resistance change. In understanding X-ray-controlled reversible resistance changes we can provide possibilities to control initial resistance states of functional materials, which could be useful for future information and energy storage devices.« less

X-ray irradiation induced reversible resistance change in Pt/TiO2/Pt cells.

PubMed

Chang, Seo Hyoung; Kim, Jungho; Phatak, Charudatta; D'Aquila, Kenneth; Kim, Seong Keun; Kim, Jiyoon; Song, Seul Ji; Hwang, Cheol Seong; Eastman, Jeffrey A; Freeland, John W; Hong, Seungbum

2014-02-25

The interaction between X-rays and matter is an intriguing topic for both fundamental science and possible applications. In particular, synchrotron-based brilliant X-ray beams have been used as a powerful diagnostic tool to unveil nanoscale phenomena in functional materials. However, it has not been widely investigated how functional materials respond to the brilliant X-rays. Here, we report the X-ray-induced reversible resistance change in 40-nm-thick TiO2 films sandwiched by Pt top and bottom electrodes, and propose the physical mechanism behind the emergent phenomenon. Our findings indicate that there exists a photovoltaic-like effect, which modulates the resistance reversibly by a few orders of magnitude, depending on the intensity of impinging X-rays. We found that this effect, combined with the X-ray irradiation induced phase transition confirmed by transmission electron microscopy, triggers a nonvolatile reversible resistance change. Understanding X-ray-controlled reversible resistance changes can provide possibilities to control initial resistance states of functional materials, which could be useful for future information and energy storage devices.

Differences in responses to X-ray exposure between osteoclast and osteoblast cells

PubMed Central

Zhang, Jian; Wang, Ziyang; Wu, Anqing; Nie, Jing; Pei, Hailong; Hu, Wentao; Wang, Bing; Shang, Peng; Li, Bingyan

2017-01-01

Abstract Radiation-induced bone loss is a potential health concern for cancer patients undergoing radiotherapy. Enhanced bone resorption by osteoclasts and decreased bone formation by osteoblasts were thought to be the main reasons. In this study, we showed that both pre-differentiating and differentiating osteoclasts were relatively sensitive to X-rays compared with osteoblasts. X-rays decreased cell viability to a greater degree in RAW264.7 cells and in differentiating cells than than in osteoblastic MC3T3-E1 cells. X-rays at up to 8 Gy had little effects on osteoblast mineralization. In contrast, X-rays at 1 Gy induced enhanced osteoclastogenesis by enhanced cell fusion, but had no effects on bone resorption. A higher dose of X-rays at 8 Gy, however, had an inhibitory effect on bone resorption. In addition, actin ring formation was disrupted by 8 Gy of X-rays and reorganized into clusters. An increased activity of Caspase 3 was found after X-ray exposure. Actin disorganization and increased apoptosis may be the potential effects of X-rays at high doses, by inhibiting osteoclast differentiation. Taken together, our data indicate high radiosensitivity of osteoclasts. X-ray irradiation at relatively low doses can activate osteoclastogenesis, but not osteogenic differentiation. The radiosensitive osteoclasts are the potentially responsive cells for X-ray-induced bone loss. PMID:28541506

Effect of caffeine on the expression of a major X-ray induced protein in human tumor cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, E.N.; Boothman, D.A.

1991-03-01

We have examined the effect of caffeine on the concomitant processes of the repair of potentially lethal damage (PLD) and the synthesis of X-ray-induced proteins in the human malignant melanoma cell line, Ul-Mel. Caffeine administered at a dose of 5mM after X radiation not only inhibited PLD repair but also markedly reduced the level of XIP269, a major X-ray-induced protein whose expression has been shown to correlate with the capacity to repair PLD. The expression of the vast majority of other cellular proteins, including seven other X-ray-induced proteins, remained unchanged following caffeine treatment. A possible role for XIP269 in cellmore » cycle delay following DNA damage by X irradiation is discussed.« less

Both Complexity and Location of DNA Damage Contribute to Cellular Senescence Induced by Ionizing Radiation

PubMed Central

Zhang, Xurui; Ye, Caiyong; Sun, Fang; Wei, Wenjun; Hu, Burong; Wang, Jufang

2016-01-01

Persistent DNA damage is considered as a main cause of cellular senescence induced by ionizing radiation. However, the molecular bases of the DNA damage and their contribution to cellular senescence are not completely clear. In this study, we found that both heavy ions and X-rays induced senescence in human uveal melanoma 92–1 cells. By measuring senescence associated-β-galactosidase and cell proliferation, we identified that heavy ions were more effective at inducing senescence than X-rays. We observed less efficient repair when DNA damage was induced by heavy ions compared with X-rays and most of the irreparable damage was complex of single strand breaks and double strand breaks, while DNA damage induced by X-rays was mostly repaired in 24 hours and the remained damage was preferentially associated with telomeric DNA. Our results suggest that DNA damage induced by heavy ion is often complex and difficult to repair, thus presents as persistent DNA damage and pushes the cell into senescence. In contrast, persistent DNA damage induced by X-rays is preferentially associated with telomeric DNA and the telomere-favored persistent DNA damage contributes to X-rays induced cellular senescence. These findings provide new insight into the understanding of high relative biological effectiveness of heavy ions relevant to cancer therapy and space radiation research. PMID:27187621

Stress-induced cortisol secretion impairs detection performance in x-ray baggage screening for hidden weapons by screening novices.

PubMed

Thomas, Livia; Schwaninger, Adrian; Heimgartner, Nadja; Hedinger, Patrik; Hofer, Franziska; Ehlert, Ulrike; Wirtz, Petra H

2014-09-01

Aviation security strongly depends on screeners' performance in the detection of threat objects in x-ray images of passenger bags. We examined for the first time the effects of stress and stress-induced cortisol increases on detection performance of hidden weapons in an x-ray baggage screening task. We randomly assigned 48 participants either to a stress or a nonstress group. The stress group was exposed to a standardized psychosocial stress test (TSST). Before and after stress/nonstress, participants had to detect threat objects in a computer-based object recognition test (X-ray ORT). We repeatedly measured salivary cortisol and X-ray ORT performance before and after stress/nonstress. Cortisol increases in reaction to psychosocial stress induction but not to nonstress independently impaired x-ray detection performance. Our results suggest that stress-induced cortisol increases at peak reactivity impair x-ray screening performance. Copyright © 2014 Society for Psychophysiological Research.

THE INACTIVATION OF DILUTE SOLUTIONS OF CRYSTALLINE TRYPSIN BY X-RADIATION

PubMed Central

McDonald, Margaret R.

1954-01-01

The activity of dilute solutions of crystalline trypsin is destroyed by x-rays. The inactivation is an exponential function of the radiation dose. The reaction yield of inactivation is independent of the intensity at which the radiation is delivered or the quality of the x-rays. The reaction yield increases with increasing concentration of trypsin, varying from 0.06 to 0.7 micromoles per liter per 1000 r for trypsin solutions ranging from 1 x 10–7 to 2 x 10–4 M. PMID:13192318

INTERACTION OF X AND ULTRAVIOLET RADIATION IN PRODUCTION OF RECESSIVE LETHALS IN DROSOPHILA MELANOGASTER (in Italian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicoletti, B.; Olivieri, G.

1962-01-01

The possibility that uv rays given to different biological systems before or after x rays could modify genetic or cytological effects is reviewed and discussed. Kaufmann and Hollaender's conclusions about the recovering effect of uv rays on chromosomal damage induced in Drosophila sperms by a pre-treatment of x rays are discussed and analyzed taking into accourt some general considerations. Preliminary results of similar experiments on the frequency of sex-linked recessive lethals induced after single and combined x + uv treatments in Drosophila sperms are reported. All our experiments indicate no effect of the uv treatment (at the given wave lengthsmore » and doses) in lowering the frequency of the x-ray-induced recessive lethals. On the contrary, there are some indications for a synergistic action between the two radiations. These results not in agreement with the generally accepted theory that uv rays do recover X-ray- induced chromosomal damages, could be expiained With the well established correlation between chromosomal rejoined breaks and genic mutations. (auth)« less

Detection of X-ray photons by solution-processed organic-inorganic perovskites

PubMed Central

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

2017-01-01

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, based on 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 immense attention. Here we demonstrate a possibility to use such inexpensive semiconductors for 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. PMID:28553368

X-ray induced chemical reaction revealed by in-situ X-ray diffraction and scanning X-ray microscopy in 15 nm resolution (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ge, Mingyuan; Liu, Wenjun; Bock, David; De Andrade, Vincent; Yan, Hanfei; Huang, Xiaojing; Marschilok, Amy; Takeuchi, Esther; Xin, Huolin; Chu, Yong S.

2016-09-01

The detection sensitivity of synchrotron-based X-ray techniques has been largely improved due to the ever increasing source brightness, which have significantly advanced ex-situ and in-situ research for energy materials, such as lithium-ion batteries. However, the strong beam-matter interaction arisen from the high beam flux can significantly modify the material structure. The parasitic beam-induced effect inevitably interferes with the intrinsic material property, which brings difficulties in interpreting experimental results, and therefore requires comprehensive evaluation. Here we present a quantitative in-situ study of the beam-effect on one electrode material Ag2VO2PO4 using four different X-ray probes with different radiation dose rate. The material system we reported exhibits interesting and reversible radiation-induced thermal and chemical reactions, which was further evaluated under electron microscopy to illustrate the underlying mechanism. The work we presented here will provide a guideline in using synchrotron X-rays to distinguish the materials' intrinsic behavior from extrinsic structure changed induced by X-rays, especially in the case of in-situ and operando study where the materials are under external field of either temperature or electric field.

A spray technique for preparing uniform large-area PIXE calibration standards from aqueous solutions

NASA Astrophysics Data System (ADS)

Menzel, N.; Hietel, B.; Leirer, M.; Szymczak, W.; Wittmaack, K.

1999-04-01

We describe a procedure for preparing reference standards that can be used to calibrate PIXE spectra of aerosol deposits collected on suitable backing films made, for example, of synthesised polymers (polypropylene, polycarbonate etc.) or chemically modified biopolymers (e.g., cellulose actetate). Aqueous solutions of well defined concentration were prepared from metal salts. The solutions were spray-deposited on cellulose acetate backings using a nebuliser. Lateral uniformity of the deposited layer over areas ranging from several mm to several cm was accomplished by raster scanning the table on which the backing was mounted. By optimising the experimental parameters, deposition could be accomplished without any detectable wetting of delicate substrates like paper. The areal density of the deposited material was calculated from the concentration of the solute, the volume of the consumed solution and the raster scanned area. The reference standards were analysed by PIXE using an external beam chamber backfilled with helium. The Si(Li) based detection system contained a thin funny filter so that X-ray spectra could be measured down to 1 keV. The proton energy on impact was 1.1 MeV. This relatively low probe energy has the advantage of producing favourable elemental X-ray peak heights relative to the bremsstrahlung-background, notably at energies between 2 and 7 keV. Under the same conditions sufficiently high X-ray yields were achieved for heavy elements like Zn and Pb. Using large area beams, bombardment-induced stress in the backing films could be kept at a low level so that very reproducible background spectra were obtained. Hence a straightforward background subtraction routine could be employed. Sensitivities were determined for 23 elements ranging from Na to Pb. Advantages and problems associated with the different metal salts are discussed briefly.

Temporal cross-correlation of x-ray free electron and optical lasers using soft x-ray pulse induced transient reflectivity.

PubMed

Krupin, O; Trigo, M; Schlotter, W F; Beye, M; Sorgenfrei, F; Turner, J J; Reis, D A; Gerken, N; Lee, S; Lee, W S; Hays, G; Acremann, Y; Abbey, B; Coffee, R; Messerschmidt, M; Hau-Riege, S P; Lapertot, G; Lüning, J; Heimann, P; Soufli, R; Fernández-Perea, M; Rowen, M; Holmes, M; Molodtsov, S L; Föhlisch, A; Wurth, W

2012-05-07

The recent development of x-ray free electron lasers providing coherent, femtosecond-long pulses of high brilliance and variable energy opens new areas of scientific research in a variety of disciplines such as physics, chemistry, and biology. Pump-probe experimental techniques which observe the temporal evolution of systems after optical or x-ray pulse excitation are one of the main experimental schemes currently in use for ultrafast studies. The key challenge in these experiments is to reliably achieve temporal and spatial overlap of the x-ray and optical pulses. Here we present measurements of the x-ray pulse induced transient change of optical reflectivity from a variety of materials covering the soft x-ray photon energy range from 500eV to 2000eV and outline the use of this technique to establish and characterize temporal synchronization of the optical-laser and FEL x-ray pulses.

Development of an adaptable coherent x-ray diffraction microscope with the emphasis on imaging hydrated specimens.

PubMed

Nam, Daewoong; Park, Jaehyun; Gallagher-Jones, Marcus; Shimada, Hiroki; Kim, Sangsoo; Kim, Sunam; Kohmura, Yoshiki; Ishikawa, Tetsuya; Song, Changyong

2013-11-01

This paper describes the development of a versatile coherent x-ray diffraction microscope capable of imaging biological specimens in solution. The microscope is a flexible platform accommodating various conditions, from low vacuum (10(-2) Pa) to helium gas filled ambient pressure. This flexibility greatly expands the application area, from in situ materials science to biology systems in their native state, by significantly relaxing restrictions to the sample environment. The coherent diffraction microscope has been used successfully to image a yeast cell immersed in buffer solution. We believe that the design of this coherent diffraction microscope can be directly adapted to various platforms such as table top soft x-ray laser, synchrotron x-ray sources, and x-ray free electron laser with minor relevant adjustments.

Development of an adaptable coherent x-ray diffraction microscope with the emphasis on imaging hydrated specimens

NASA Astrophysics Data System (ADS)

Nam, Daewoong; Park, Jaehyun; Gallagher-Jones, Marcus; Shimada, Hiroki; Kim, Sangsoo; Kim, Sunam; Kohmura, Yoshiki; Ishikawa, Tetsuya; Song, Changyong

2013-11-01

This paper describes the development of a versatile coherent x-ray diffraction microscope capable of imaging biological specimens in solution. The microscope is a flexible platform accommodating various conditions, from low vacuum (10-2 Pa) to helium gas filled ambient pressure. This flexibility greatly expands the application area, from in situ materials science to biology systems in their native state, by significantly relaxing restrictions to the sample environment. The coherent diffraction microscope has been used successfully to image a yeast cell immersed in buffer solution. We believe that the design of this coherent diffraction microscope can be directly adapted to various platforms such as table top soft x-ray laser, synchrotron x-ray sources, and x-ray free electron laser with minor relevant adjustments.

Antioxidant protects blood-testis barrier against synchrotron radiation X-ray-induced disruption

PubMed Central

Zhang, Tingting; Liu, Tengyuan; Shao, Jiaxiang; Sheng, Caibin; Hong, Yunyi; Ying, Weihai; Xia, Weiliang

2015-01-01

Synchrotron radiation (SR) X-ray has wide biomedical applications including high resolution imaging and brain tumor therapy due to its special properties of high coherence, monochromaticity and high intensity. However, its interaction with biological tissues remains poorly understood. In this study, we used the rat testis as a model to investigate how SR X-ray would induce tissue responses, especially the blood-testis barrier (BTB) because BTB dynamics are critical for spermatogenesis. We irradiated the male gonad with increasing doses of SR X-ray and obtained the testicles 1, 10 and 20 d after the exposures. The testicle weight and seminiferous tubule diameter reduced in a dose- and time-dependent manner. Cryosections of testes were stained with tight junction (TJ) component proteins such as occludin, claudin-11, JAM-A and ZO-1. Morphologically, increasing doses of SR X-ray consistently induced developing germ cell sloughing from the seminiferous tubules, accompanied by shrinkage of the tubules. Interestingly, TJ constituent proteins appeared to be induced by the increasing doses of SR X-ray. Up to 20 d after SR X-ray irradiation, there also appeared to be time-dependent changes on the steady-state level of these protein exhibiting differential patterns at 20-day after exposure, with JAM-A/claudin-11 still being up-regulated whereas occludin/ZO-1 being down-regulated. More importantly, the BTB damage induced by 40 Gy of SR X-ray could be significantly attenuated by antioxidant N-Acetyl-L-Cysteine (NAC) at a dose of 125 mg/kg. Taken together, our studies characterized the changes of TJ component proteins after SR X-ray irradiation, illustrating the possible protective effects of antioxidant NAC to BTB integrity. PMID:26413412

Metal-insulator transition in NiS2-xSex

NASA Astrophysics Data System (ADS)

Kuneš, J.; Baldassarre, L.; Schächner, B.; Rabia, K.; Kuntscher, C. A.; Korotin, Dm. M.; Anisimov, V. I.; McLeod, J. A.; Kurmaev, E. Z.; Moewes, A.

2010-01-01

The origin of the gap in NiS2 as well as the pressure- and doping-induced metal-insulator transition in the NiS2-xSex solid solutions are investigated both theoretically using the first-principles band structures combined with the dynamical mean-field approximation for the electronic correlations and experimentally by means of infrared and x-ray absorption spectroscopies. The bonding-antibonding splitting in the S-S (Se-Se) dimer is identified as the main parameter controlling the size of the charge gap. The implications for the metal-insulator transition driven by pressure and Se doping are discussed.

X-ray diffraction and reflectivity validation of the depletion attraction in the competitive adsorption of lung surfactant and albumin.

PubMed

Stenger, Patrick C; Wu, Guohui; Miller, Chad E; Chi, Eva Y; Frey, Shelli L; Lee, Ka Yee C; Majewski, Jaroslaw; Kjaer, Kristian; Zasadzinski, Joseph A

2009-08-05

Lung surfactant (LS) and albumin compete for the air-water interface when both are present in solution. Equilibrium favors LS because it has a lower equilibrium surface pressure, but the smaller albumin is kinetically favored by faster diffusion. Albumin at the interface creates an energy barrier to subsequent LS adsorption that can be overcome by the depletion attraction induced by polyethylene glycol (PEG) in solution. A combination of grazing incidence x-ray diffraction (GIXD), x-ray reflectivity (XR), and pressure-area isotherms provides molecular-resolution information on the location and configuration of LS, albumin, and polymer. XR shows an average electron density similar to that of albumin at low surface pressures, whereas GIXD shows a heterogeneous interface with coexisting LS and albumin domains at higher surface pressures. Albumin induces a slightly larger lattice spacing and greater molecular tilt, similar in effect to a small decrease in the surface pressure. XR shows that adding PEG to the LS-albumin subphase restores the characteristic LS electron density profile at the interface, and confirms that PEG is depleted near the interface. GIXD shows the same LS Bragg peaks and Bragg rods as on a pristine interface, but with a more compact lattice corresponding to a small increase in the surface pressure. These results confirm that albumin adsorption creates a physical barrier that inhibits LS adsorption, and that PEG in the subphase generates a depletion attraction between the LS aggregates and the interface that enhances LS adsorption without substantially altering the structure or properties of the LS monolayer.

Live Dynamics of 53BP1 Foci Following Simultaneous Induction of Clustered and Dispersed DNA Damage in U2OS Cells

PubMed Central

Sollazzo, Alice; Brzozowska, Beata; Cheng, Lei; Lundholm, Lovisa; Scherthan, Harry

2018-01-01

Cells react differently to clustered and dispersed DNA double strand breaks (DSB). Little is known about the initial reaction to simultaneous induction of DSBs with different complexities. Here, we used live cell microscopy to analyse the behaviour of 53BP1-GFP (green fluorescence protein) foci formation at DSBs induced in U2OS cells by alpha particles, X-rays or mixed beams over a 75 min period post irradiation. X-ray-induced foci rapidly increased and declined over the observation interval. After an initial increase, mixed beam-induced foci remained at a constant level over the observation interval, similarly as alpha-induced foci. The average areas of radiation-induced foci were similar for mixed beams and X-rays, being significantly smaller than those induced by alpha particles. Pixel intensities were highest for mixed beam-induced foci and showed the lowest level of variability over time as compared to foci induced by alphas and X-rays alone. Finally, mixed beam-exposed foci showed the lowest level of mobility as compared to alpha and X-ray exposure. The results suggest paralysation of chromatin around foci containing clustered DNA damage. PMID:29419809

Halide Ions Effects on Surface Excess of Long Chain Ionic Liquids Water Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wenjie; Sung, Woongmo; Ao, Mingqi

2013-10-07

The interfacial structure and composition of water solutions with alkylimidazolium ionic liquids varying in their halide anions ([C12mim][X], X = Cl and I) were investigated by X-ray near-total-reflection fluorescence spectroscopy and X-ray reflectivity measurements. We demonstrate that X-ray fluorescence and reflectivity techniques provide a more direct measurement of surface adsorption. Furthermore, we show that for [C12mim][Cl] and [C12mim][I] solutions with mixed inorganic salts (NaI, NaCl), I– ions replace Cl– above the critical micelle concentration (CMC) of [C12mim][Cl] at much lower concentrations of NaI, whereas NaCl concentrations a hundred times higher than the CMC of [C12mim][I] only partially replace the I–more » at the interface. Our surface-sensitive X-ray diffraction and spectroscopy provide two independent tools to directly determine the surface adsorption of ionic surfactants and the interfacial composition of the surface films.« less

Protective role of Aloe vera against X-ray induced testicular dysfunction.

PubMed

Bala, S; Chugh, N A; Bansal, S C; Garg, M L; Koul, A

2017-09-01

The present investigation was carried out to evaluate the possible radioprotective potential of an Aloe vera extract against whole-body X-ray irradiation-induced testicular alterations in mice. Male balb/c mice were divided into four groups: control, A. vera, X-ray and A. vera pre-treated + X-ray irradiated. Histopathological examination revealed significant structural alterations in testes after X-ray exposure, which was also associated with the presence of apoptotic cells as assessed by TUNEL assay. X-ray irradiation resulted in elevation in the levels of reactive oxygen species, lipid peroxidation, a reduction in glutathione concentration and enhanced activities of antioxidant enzymes such as glutathione reductase, glutathione peroxidase, catalase, superoxide dismutase and glutathione-S-transferase. Sperm count/motility and testosterone levels were significantly decreased in the irradiated group. Irradiated animals pre-treated with A. vera extract revealed an improvement in antioxidant status, inhibition of lipid peroxides, apoptotic cell formation and enhanced testicular parameters when compared to the X-ray-exposed group. These findings suggest that A. vera extract could ameliorate X-ray-induced damage due to its free radical scavenging properties and its potential to boost cellular antioxidant defence machinery. © 2016 Blackwell Verlag GmbH.

Automatic pelvis segmentation from x-ray images of a mouse model

NASA Astrophysics Data System (ADS)

Al Okashi, Omar M.; Du, Hongbo; Al-Assam, Hisham

2017-05-01

The automatic detection and quantification of skeletal structures has a variety of different applications for biological research. Accurate segmentation of the pelvis from X-ray images of mice in a high-throughput project such as the Mouse Genomes Project not only saves time and cost but also helps achieving an unbiased quantitative analysis within the phenotyping pipeline. This paper proposes an automatic solution for pelvis segmentation based on structural and orientation properties of the pelvis in X-ray images. The solution consists of three stages including pre-processing image to extract pelvis area, initial pelvis mask preparation and final pelvis segmentation. Experimental results on a set of 100 X-ray images showed consistent performance of the algorithm. The automated solution overcomes the weaknesses of a manual annotation procedure where intra- and inter-observer variations cannot be avoided.

The GALAXIE all-optical FEL project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenzweig, J. B.; Arab, E.; Andonian, G.

2012-12-21

We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 {mu}m laser development, ultra-highmore » brightness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.« less

A neutron-X-ray, NMR and calorimetric study of glassy Probucol synthesized using containerless techniques

NASA Astrophysics Data System (ADS)

Weber, J. K. R.; Benmore, C. J.; Tailor, A. N.; Tumber, S. K.; Neuefeind, J.; Cherry, B.; Yarger, J. L.; Mou, Q.; Weber, W.; Byrn, S. R.

2013-10-01

Acoustic levitation was used to trap 1-3 mm diameter drops of Probucol and other pharmaceutical materials in containerless conditions. Samples were studied in situ using X-ray diffraction and ex situ using neutron diffraction, NMR and DSC techniques. The materials were brought into non-equilibrium states by supersaturating solutions or by supercooling melts. The glass transition and crystallization temperatures of glassy Probucol were 29 ± 1 and 71 ± 1 °C respectively. The glassy form was stable with a shelf life of at least 8 months. A neutron/X-ray difference function of the glass showed that while molecular sub-groups remain rigid, many of the hydrogen correlations observed in the crystal become smeared out in the disordered material. The glass is principally comprised of slightly distorted Form I Probucol molecules with disordered packing rather than large changes in the individual molecular structure. Avoiding surface contact-induced nucleation provided access to highly non-equilibrium phases and enabled synthesis of phase-pure glasses.

Angular correlations of photons from solution diffraction at a free-electron laser encode molecular structure

DOE PAGES

Mendez, Derek; Watkins, Herschel; Qiao, Shenglan; ...

2016-09-26

During X-ray exposure of a molecular solution, photons scattered from the same molecule are correlated. If molecular motion is insignificant during exposure, then differences in momentum transfer between correlated photons are direct measurements of the molecular structure. In conventional small- and wide-angle solution scattering, photon correlations are ignored. This report presents advances in a new biomolecular structural analysis technique, correlated X-ray scattering (CXS), which uses angular intensity correlations to recover hidden structural details from molecules in solution. Due to its intense rapid pulses, an X-ray free electron laser (XFEL) is an excellent tool for CXS experiments. A protocol is outlinedmore » for analysis of a CXS data set comprising a total of half a million X-ray exposures of solutions of small gold nanoparticles recorded at the Spring-8 Ångström Compact XFEL facility (SACLA). From the scattered intensities and their correlations, two populations of nanoparticle domains within the solution are distinguished: small twinned, and large probably non-twinned domains. Finally, it is shown analytically how, in a solution measurement, twinning information is only accessible via intensity correlations, demonstrating how CXS reveals atomic-level information from a disordered solution of like molecules.« less

Probing molecular dynamics in solution with x-ray valence-to-core spectroscopy

NASA Astrophysics Data System (ADS)

Doumy, Gilles; March, Anne Marie; Tu, Ming-Feng; Al Haddad, Andre; Southworth, Stephen; Young, Linda; Walko, Donald; Bostedt, Christoph

2017-04-01

Hard X-ray spectroscopies are powerful tools for probing the electronic and geometric structure of molecules in complex or disordered systems and have been particularly useful for studying molecules in the solution phase. They are element specific, sensitive to the electronic structure and the local arrangements of surrounding atoms of the element being selectively probed. When combined in a pump-probe scheme with ultrafast lasers, X-ray spectroscopies can be used to track the evolution of structural changes that occur after photoexcitation. Efficient use of hard x-ray radiation coming from high brilliance synchrotrons and upcoming high repetition rate X-ray Free Electron Lasers requires MHz repetition rate lasers and data acquisition systems. High information content Valence-to-Core x-ray emission is directly sensitive to the molecular orbitals involved in photochemistry. We report on recent progress towards fully enabling this photon-hungry technique for the study of time-resolved molecular dynamics, including efficient detection and use of polychromatic x-ray micro-probe at the Advanced Photon Source. Work was supported by the U.S. Department of Energy, Office of Science, Chemical Sciences, Geosciences, and Biosciences Division.

X-ray photoelectron spectroscopy study of chemically-etched Nd-Ce-Cu-O surfaces

NASA Technical Reports Server (NTRS)

Vasquez, R. P.; Gupta, A.; Kussmaul, A.

1991-01-01

Acetic acid, Br2, and HCl solutions are investigated for removing insulating species from Nd(1.85)Ce(0.15)CuO(4-delta) (NCCO) thin film surfaces. X-ray photoelectron spectroscopy (XPS) shows that the HCl etch is most effective, yielding O 1s spectra comparable to those obtained from samples cleaned in vacuum and a clear Fermi edge in the valence band region. Reduction and oxidation reversibly induces and eliminates, respectively, Fermi level states for undoped samples, but has no clearly observable effect on the XPS spectra for doped samples. Reactivity to air is much less for NCCO compared to hole superconductors, which is attributed to the lack of reactive alkaline earth elements in NCCO.

Tribocorrosion Failure Mechanism of TiN/SiOx Duplex Coating Deposited on AISI304 Stainless Steel.

PubMed

Chen, Qiang; Xie, Zhiwen; Chen, Tian; Gong, Feng

2016-11-26

TiN/SiO x duplex coatings were synthesized on AISI304 stainless steel by plasma immersion ion implantation and deposition (PIIID) followed by radio frequency magnetron sputtering (RFMS). The microstructure and tribocorrosion failure behaviors of the duplex coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, reciprocating-sliding tribometer, and electrochemical tests. The as-deposited duplex coating had a two-layered columnar growth structure consisting of face-centered cubic TiN and amorphous SiO x . Sliding tests showed that the TiN interlayer had good adhesion with the substrate, but the SiO x layer suffered from severe delamination failure. Friction force induced a number of micro-cracks in the coating, which provided channels for the diffusion of NaCl solution. The tribocorrosion test showed that the duplex coating exhibited a lower wear-performance in NaCl solution than in ambient atmosphere. Multi-scale chloride ion corrosion occurred simultaneously and substantially degraded the bonding strength of the columnar crystals or neighboring layers. Force-corrosion synergy damage eventually led to multi-degradation failure of the duplex coating. The presented results provide a comprehensive understanding of the tribocorrosion failure mechanism in coatings with duplex architecture.

Enhanced neoplastic transformation by mammography X rays relative to 200 kVp X rays: indication for a strong dependence on photon energy of the RBE(M) for various end points.

PubMed

Frankenberg, D; Kelnhofer, K; Bär, K; Frankenberg-Schwager, M

2002-01-01

The fundamental assumption implicit in the use of the atomic bomb survivor data to derive risk estimates is that the gamma rays of Hiroshima and Nagasaki are considered to have biological efficiencies equal to those of other low-LET radiations up to 10 keV/microm, including mammography X rays. Microdosimetric and radiobiological data contradict this assumption. It is therefore of scientific and public interest to evaluate the efficiency of mammography X rays (25-30 kVp) to induce cancer. In this study, the efficiency of mammography X rays relative to 200 kVp X rays to induce neoplastic cell transformation was evaluated using cells of a human hybrid cell line (CGL1). For both radiations, a linear-quadratic dose-effect relationship was observed for neoplastic transformation of CGL1 cells; there was a strong linear component for the 29 kVp X rays. The RBE(M) of mammography X rays relative to 200 kVp X rays was determined to be about 4 for doses < or = 0.5 Gy. A comparison of the electron fluences for both X rays provides strong evidence that electrons with energies of < or = 15 keV can induce neoplastic transformation of CGL1 cells. Both the data available in the literature and the results of the present study strongly suggest an increase of RBE(M) for carcinogenesis in animals, neoplastic cell transformation, and clastogenic effects with decreasing photon energy or increasing LET to an RBE(M) approximately 8 for mammography X rays relative to 60Co gamma rays.

Mixed-Metal Strategy on Metal-Organic Frameworks (MOFs) for Functionalities Expansion: Co Substitution Induces Aerobic Oxidation of Cyclohexene over Inactive Ni-MOF-74.

PubMed

Sun, Dengrong; Sun, Fangxiang; Deng, Xiaoyu; Li, Zhaohui

2015-09-08

Different amounts of Co-substituted Ni-MOF-74 have been prepared via a post-synthetic metal exchange. Inductively coupled plasma mass spectrometry, powder X-ray diffraction (XRD), N2 adsorption/desorption, and extended X-ray absorption fine structure (EXAFS) analyses indicated the successful metathesis between Co and Ni in Ni-MOF-74 to form the solid-solution-like mixed-metal Co/Ni-MOF-74. It was found that introduction of active Co into the Ni-MOF-74 framework enabled the inert Ni-MOF-74 to show activity for cyclohexene oxidation. Since Co was favorably substituted at positions more accessible to the substrate, the mixed-metal Co/Ni-MOF-74 showed superior catalytic performance, compared with pure Co-MOF-74 containing a similar amount of Co. This study provides a facile method to develop solid-solution-like MOFs for heterogeneous catalysis and highlights the great potential of this mixed-metal strategy in the development of MOFs with specific endowed functionalities.

Hybrid accretion disks in active galactic nuclei. I - Structure and spectra

NASA Technical Reports Server (NTRS)

Wandel, Amri; Liang, Edison P.

1991-01-01

A unified treatment is presented of the two distinct states of vertically thin AGN accretion disks: a cool (about 10 to the 6th K) optically thick solution, and a hot (about 10 to the 9th K) optically thin solution. A generalized formalism and a new radiative cooling equation valid in both regimes are introduced. A new luminosity limit is found at which the hot and cool alpha solutions merge into a single solution of intermediate optical depth. Analytic solutions for the disk structure are given, and output spectra are computed numerically. This is used to demonstrate the prospect of fitting AGN broadband spectra containing both the UV bump as well as the hard X-ray and gamma-ray tail, using a single accretion disk model. Such models are found to make definite predictions about the observed spectrum, such as the relation between the hard X-ray spectral index, the UV-to-X-ray luminosity ratio, and a feature of about 1 MeV.

Synchrotron x-ray imaging of acoustic cavitation bubbles induced by acoustic excitation

NASA Astrophysics Data System (ADS)

Jung, Sung Yong; Park, Han Wook; Park, Sung Ho; Lee, Sang Joon

2017-04-01

The cavitation induced by acoustic excitation has been widely applied in various biomedical applications because cavitation bubbles can enhance the exchanges of mass and energy. In order to minimize the hazardous effects of the induced cavitation, it is essential to understand the spatial distribution of cavitation bubbles. The spatial distribution of cavitation bubbles visualized by the synchrotron x-ray imaging technique is compared to that obtained with a conventional x-ray tube. Cavitation bubbles with high density in the region close to the tip of the probe are visualized using the synchrotron x-ray imaging technique, however, the spatial distribution of cavitation bubbles in the whole ultrasound field is not detected. In this study, the effects of the ultrasound power of acoustic excitation and working medium on the shape and density of the induced cavitation bubbles are examined. As a result, the synchrotron x-ray imaging technique is useful for visualizing spatial distributions of cavitation bubbles, and it could be used for optimizing the operation conditions of acoustic cavitation.

Local Structure Determination of Carbon/Nickel Ferrite Composite Nanofibers Probed by X-ray Absorption Spectroscopy.

PubMed

Nilmoung, Sukunya; Kidkhunthod, Pinit; Maensiri, Santi

2015-11-01

Carbon/NiFe2O4 composite nanofibers have been successfully prepared by electrospinning method using a various concentration solution of Ni and Fe nitrates dispersed into polyacrylonitride (PAN) solution in N,N' dimethylformamide. The phase and mophology of PAN/NiFe2O4 composite samples were characterized and investigated by X-ray diffraction and scanning electron microscopy. The magnetic properties of the prepared samples were measured at ambient temperature by a vibrating sample magnetometer. It is found that all composite samples exhibit ferromagnetism. This could be local-structurally explained by the existed oxidation states of Ni2+ and Fe3+ in the samples. Moreover, local environments around Ni and Fe ions could be revealed by X-ray absorption spectroscopy (XAS) measurement including X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS).

X-ray structure investigation of some substituted indoles, and the x-ray crystal of 1,1'-bishomocubane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quarles, William G.

1970-05-01

The crystal structures of 5-methoxytryptamine, melatonin, and the p-bromobenzoate of 1,1'-bishomocubane have been solved by x-ray diffraction methods. A computer program for the trial and error solution of crystal structures is also described here.

X-ray ptychography

NASA Astrophysics Data System (ADS)

Pfeiffer, Franz

2018-01-01

X-ray ptychographic microscopy combines the advantages of raster scanning X-ray microscopy with the more recently developed techniques of coherent diffraction imaging. It is limited neither by the fabricational challenges associated with X-ray optics nor by the requirements of isolated specimen preparation, and offers in principle wavelength-limited resolution, as well as stable access and solution to the phase problem. In this Review, we discuss the basic principles of X-ray ptychography and summarize the main milestones in the evolution of X-ray ptychographic microscopy and tomography over the past ten years, since its first demonstration with X-rays. We also highlight the potential for applications in the life and materials sciences, and discuss the latest advanced concepts and probable future developments.

Electronic structure and soft-X-ray-induced photoreduction studies of iron-based magnetic polyoxometalates of type {(M)M5}12Fe(III)30 (M = Mo(VI), W(VI)).

PubMed

Kuepper, Karsten; Derks, Christine; Taubitz, Christian; Prinz, Manuel; Joly, Loïc; Kappler, Jean-Paul; Postnikov, Andrei; Yang, Wanli; Kuznetsova, Tatyana V; Wiedwald, Ulf; Ziemann, Paul; Neumann, Manfred

2013-06-14

Giant Keplerate-type molecules with a {Mo72Fe30} core show a number of very interesting properties, making them particularly promising for various applications. So far, only limited data on the electronic structure of these molecules from X-ray spectra and electronic structure calculations have been available. Here we present a combined electronic and magnetic structure study of three Keplerate-type nanospheres--two with a {Mo72Fe30} core and one with a {W72Fe30} core by means of X-ray absorption spectroscopy, X-ray magnetic circular dichroism (XMCD), SQUID magnetometry, and complementary theoretical approaches. Furthermore, we present detailed studies of the Fe(3+)-to-Fe(2+) photoreduction process, which is induced under soft X-ray radiation in these molecules. We observe that the photoreduction rate greatly depends on the ligand structure surrounding the Fe ions, with negatively charged ligands leading to a dramatically reduced photoreduction rate. This opens the possibility of tailoring such polyoxometalates by X-ray spectroscopic studies and also for potential applications in the field of X-ray induced photochemistry.

History and Solution of the Phase Problem in theTheory of Structure Determination of Crystals from X-ray Diffraction Experiments

ScienceCinema

Wolf, Emil [University of Rochester, Rochester, New York, United States

2017-12-09

Since the pioneering work of Max von Laue on interference and diffraction of x-rays, carried out almost 100 years ago, numerous attempts have been made to determine structures of crystalline media from x-ray diffraction experiments. The usefulness of all of them has been limited by the inability of measuring phases of the diffracted beams. In this talk, the most important research carried out in this field will be reviewed and a recently obtained solution of the phase problem will be presented.

A Calcium Enterolith in a Patient with Crohn's Disease and Its In Vitro Dissolubility in Citric Acid

PubMed Central

Urata, Haruo; Ohmori, Masayasu; Kondo, Yoshitaka; Kawahara, Yoshiro; Okada, Hiroyuki

2017-01-01

The microstructure and dissolubility of a calcified enterolith and enterolith pieces removed from a 26-year-old Japanese woman with Crohn's disease were analyzed using scanning electron microscopy and energy dispersive X-ray spectroscopy. The enterolith showed a multilayered structure with fatty acid calcium and magnesium phosphate. The amount of calcium, magnesium, and phosphate decreased after they were immersed in a citric acid solution, suggesting a potential contribution of acidic aqueous solution to elute inorganic substances contained in calcified enteroliths. This is the first study to investigate the in vitro dissolubility of calcified enteroliths induced by citric acid solution. PMID:29082049

Surface studies of solids using integral x-ray-induced photoemission yield

DOE PAGES

Stoupin, Stanislav; Zhernenkov, Mikhail; Shi, Bing

2016-11-22

X-ray induced photoemission yield contains structural information complementary to that provided by X-ray Fresnel reflectivity, which presents an advantage to a wide variety of surface studies if this information is made easily accessible. Photoemission in materials research is commonly acknowledged as a method with a probing depth limited by the escape depth of the photoelectrons. Here we show that the integral hard-X-ray-induced photoemission yield is modulated by the Fresnel reflectivity of a multilayer structure and carries structural information that extends well beyond the photoelectron escape depth. A simple electric self-detection of the integral photoemission yield and Fourier data analysis permitmore » extraction of thicknesses of individual layers. The approach does not require detection of the reflected radiation and can be considered as a framework for non-invasive evaluation of buried layers with hard X-rays under grazing incidence.« less

Surface studies of solids using integral X-ray-induced photoemission yield

PubMed Central

Stoupin, Stanislav; Zhernenkov, Mikhail; Shi, Bing

2016-01-01

X-ray induced photoemission yield contains structural information complementary to that provided by X-ray Fresnel reflectivity, which presents an advantage to a wide variety of surface studies if this information is made easily accessible. Photoemission in materials research is commonly acknowledged as a method with a probing depth limited by the escape depth of the photoelectrons. Here we show that the integral hard-X-ray-induced photoemission yield is modulated by the Fresnel reflectivity of a multilayer structure and carries structural information that extends well beyond the photoelectron escape depth. A simple electric self-detection of the integral photoemission yield and Fourier data analysis permit extraction of thicknesses of individual layers. The approach does not require detection of the reflected radiation and can be considered as a framework for non-invasive evaluation of buried layers with hard X-rays under grazing incidence. PMID:27874041

Phase transformations in the hematite-metal system during mechanical alloying

NASA Astrophysics Data System (ADS)

Kozlov, K. A.; Shabashov, V. A.; Litvinov, A. V.; Sagaradze, V. V.

2009-04-01

Mössbauer spectroscopy and X-ray diffraction are used to show that the phase transformations in hematite α-Fe2O3-metal ( M = Fe, Ni, Ti, Zr) powder mixtures induced by severe cold plastic deformation in ball mills occur via the formation of M-Fe-O solid solutions, redox reactions with the reduction of metallic iron, and the formation of secondary M x O y oxides and M x Fe y intermetallics. Mechanical activation in a ball mill is compared to that under high-pressure shear in Bridgman anvils. The transformations that take place in a ball mill are found to have several stages and to be accelerated.

Chemical Speciation and Bond Lengths of Organic Solutes by Core-Level Spectroscopy: pH and Solvent Influence on p-Aminobenzoic Acid.

PubMed

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

2015-05-04

Through X-ray absorption and emission spectroscopies, the chemical, electronic and structural properties of organic species in solution can be observed. Near-edge X-ray absorption fine structure (NEXAFS) and resonant inelastic X-ray scattering (RIXS) measurements at the nitrogen K-edge of para-aminobenzoic acid reveal both pH- and solvent-dependent variations in the ionisation potential (IP), 1s→π* resonances and HOMO-LUMO gap. These changes unequivocally identify the chemical species (neutral, cationic or anionic) present in solution. It is shown how this incisive chemical state sensitivity is further enhanced by the possibility of quantitative bond length determination, based on the analysis of chemical shifts in IPs and σ* shape resonances in the NEXAFS spectra. This provides experimental access to detecting even minor variations in the molecular structure of solutes in solution, thereby providing an avenue to examining computational predictions of solute properties and solute-solvent interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Osmotically Induced Reversible Transitions in Lipid-DNA Mesophases

PubMed Central

Danino, Dganit; Kesselman, Ellina; Saper, Gadiel; Petrache, Horia I.; Harries, Daniel

2009-01-01

We follow the effect of osmotic pressure on isoelectric complexes that self-assemble from mixtures of DNA and mixed neutral and cationic lipids. Using small angle x-ray diffraction and freeze-fracture cryo-electron microscopy, we find that lamellar complexes known to form in aqueous solutions can reversibly transition to hexagonal mesophases under high enough osmotic stress exerted by adding a neutral polymer. Using molecular spacings derived from x-ray diffraction, we estimate the reversible osmotic pressure-volume (Π-V) work needed to induce this transition. We find that the transition free energy is comparable to the work required to elastically bend lipid layers around DNA. Consistent with this, the required work is significantly lowered by an addition of hexanol, which is known to soften lipid bilayers. Our findings not only help to resolve the free-energy contributions associated with lipid-DNA complex formation, but they also demonstrate the importance that osmotic stress can have to the macromolecular phase geometry in realistic biological environments. PMID:19348739

Changes of Gene Expression in the Apoptosis Pathway in Lncap and PC3 Cells Exposed to X-Rays or Protons

NASA Technical Reports Server (NTRS)

Zhang, Ye; Rohde, Larry H.; Mehta, Satish K.; Pierson, Duane L.; Wu, Honglu

2009-01-01

Radio-resistant or recurrent prostate cancer represents a serious health risk for approximately 20%-30% of patients treated with primary radiation therapy for clinically localized prostate cancer. In our current studies, we investigated the expressions of apoptosis related gene expression profile (84 genes) in two distinct prostate cell lines Lncap (P53+ and AR+) and PC3 (P53- and AR-) before and after exposure to X-rays or protons, using cDNA PCR arrays. In Lncap cells, 10Gy X-ray radiation significantly induced the expression of 19 out of 84 genes at 4h after irradiation. The changed genes were mostly in death and death receptor domain families, TNF ligand and receptor families, and apoptotic group of the BCL2 family, especially in P53 related genes, such as FAS, BAX, BAK1 and GADD45A. In PC3, X-rays only induced the expression of 3 genes, including an increased expression of BIRC3. There was no difference of the X-ray mediated cell killing in both cell lines using the cell cycle analysis. However, these X-ray-induced gene expression differences between PC3 and Lncap may explain the phenotype of PC3 cells that shows more tolerant not only to radiation, but also to other apoptosis inducing and sensitizing reagents. To compare the effectiveness of cell killing with X-rays, we also exposed PC3 cells to 10Gy protons at the Bragg peak region. Protons did not induce more apoptosis than X-rays for the same dose. In comparison to X-rays, protons significantly altered expressions of 13 genes in PC3, which included decreased expressions of anti-apoptosis genes (BCL2 and BCL2L2), and increased expressions of death and death receptor domain family genes, TNF ligand and receptor family and several kinases (FAS, DAPK1 and RIPK2). These data suggest that proton treatment is more effective in influencing the apoptosis pathways in PC3 cells than X-rays, thus protons may be more effective in the treatment of specific prostate tumor.

High Resolution X-ray-Induced Acoustic Tomography

PubMed Central

Xiang, Liangzhong; Tang, Shanshan; Ahmad, Moiz; Xing, Lei

2016-01-01

Absorption based CT imaging has been an invaluable tool in medical diagnosis, biology, and materials science. However, CT requires a large set of projection data and high radiation dose to achieve superior image quality. In this letter, we report a new imaging modality, X-ray Induced Acoustic Tomography (XACT), which takes advantages of high sensitivity to X-ray absorption and high ultrasonic resolution in a single modality. A single projection X-ray exposure is sufficient to generate acoustic signals in 3D space because the X-ray generated acoustic waves are of a spherical nature and propagate in all directions from their point of generation. We demonstrate the successful reconstruction of gold fiducial markers with a spatial resolution of about 350 μm. XACT reveals a new imaging mechanism and provides uncharted opportunities for structural determination with X-ray. PMID:27189746

Tritium analysis of divertor tiles used in JET ITER-like wall campaigns by means of β-ray induced x-ray spectrometry

NASA Astrophysics Data System (ADS)

Hatano, Y.; Yumizuru, K.; Koivuranta, S.; Likonen, J.; Hara, M.; Matsuyama, M.; Masuzaki, S.; Tokitani, M.; Asakura, N.; Isobe, K.; Hayashi, T.; Baron-Wiechec, A.; Widdowson, A.; contributors, JET

2017-12-01

Energy spectra of β-ray induced x-rays from divertor tiles used in ITER-like wall campaigns of the Joint European Torus were measured to examine tritium (T) penetration into tungsten (W) layers. The penetration depth of T evaluated from the intensity ratio of W(Lα) x-rays to W(Mα) x-rays showed clear correlation with poloidal position; the penetration depth at the upper divertor region reached several micrometers, while that at the lower divertor region was less than 500 nm. The deep penetration at the upper part was ascribed to the implantation of high energy T produced by DD fusion reactions. The poloidal distribution of total x-ray intensity indicated higher T retention in the inboard side than the outboard side of the divertor region.

Transient lattice contraction in the solid to plasma transition of x-ray heated xenon clusters

NASA Astrophysics Data System (ADS)

Bostedt, C.; Ferguson, K.; Gorkhover, T.; Bucksbaum, P. H.; Boutet, S.; Koglin, J. E.; Lutman, A.; Marinelli, A.; Turner, J.; Bucher, M.; Ho, P.; Knight, C.; Young, L.; Fukuzawa, H.; Kumagai, Y.; Ueda, K.; Nagaya, K.; Messerschmidt, M.; Williams, G.

2016-05-01

Any sample in the focus of intense x-ray pulses will be transformed into a nanoplasma within femtoseconds. We have employed the novel two-color two-pulse mode available at the Linac Coherent Light Source free-electron laser to investigate the structural dynamics in nanoparticles upon x-ray exposure. We find that the nanoparticle transiently contracts within the first 80 fs following x-ray irradiation before ultimately disintegrating in a rapid hydrodynamic expansion. The contraction can be attributed to the massive x-ray induced electronic excitation that induces a collective change in the bond character of the nanoparticles. Alternative explanations for the contraction include a compression wave stemming from a rapid surface explosion of the nanoparticle. Computer simulations under way can elucidate the dominant contraction mechanism and yield further insight into the complex x-ray induced dynamics in nanoscale samples. This work is funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, under Contract No. DE-AC02-06CH11357.

Advancements and Application of Microsecond Synchrotron X-ray Footprinting at the Advanced Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Sayan; Celestre, Rich; Feng, Jun

2016-01-02

The method of synchrotron X-ray protein footprinting (XF-MS) is used to determine protein conformational changes, folding, protein-protein and protein-ligand interactions, providing information which is often difficult to obtain using X-ray crystallography and other common structural biology methods [1 G. Xu and M.R. Chance, Chemical Reviews 107, 3514–3543 (2007). [CrossRef], [PubMed], [Web of Science ®], [Google Scholar] –3 V.N. Bavro, Biochem Soc Trans 43, 983–994 (2015). [CrossRef], [PubMed], [Web of Science ®], [Google Scholar] ]. The technique uses comparative in situ labeling of solvent-accessible side chains by highly reactive hydroxyl radicals (•OH) in buffered aqueous solution under different assay conditions. Inmore » regions where a protein is folded or binds a partner, these •OH susceptible sites are inaccessible to solvent, and therefore protected from labeling. The •OH are generated by the ionization of water using high-flux-density X-rays. High-flux density is a key factor for XF-MS labeling because obtaining an adequate steady-state concentration of hydroxyl radical within a short irradiation time is necessary to minimize radiation-induced secondary damage and also to overcome various scavenging reactions that reduce the yield of labeled side chains.« less

Orbital Parameters for the X-Ray Pulsar IGR J16393-4643

NASA Astrophysics Data System (ADS)

Thompson, Thomas W. J.; Tomsick, John A.; Rothschild, Richard E.; in't Zand, J. J. M.; Walter, Roland

2006-09-01

With recent and archival Rossi X-Ray Timing Explorer (RXTE) X-ray measurements of the heavily obscured X-ray pulsar IGR J16393-4643, we carried out a pulse timing analysis to determine the orbital parameters. Assuming a circular orbit, we phase-connected data spanning over 1.5 yr. The most likely orbital solution has a projected semimajor axis of 43+/-2 lt-s and an orbital period of 3.6875+/-0.0006 days. This implies a mass function of 6.5+/-1.1 Msolar and confirms that this INTEGRAL source is a high-mass X-ray binary (HMXB) system. By including eccentricity in the orbital model, we find e<0.25 at the 2 σ level. The 3.7 day orbital period and the previously known ~910 s pulse period place the system in the region of the Corbet diagram populated by supergiant wind accretors, and the low eccentricity is also consistent with this type of system. Finally, it should be noted that although the 3.7 day solution is the most likely one, we cannot completely rule out two other solutions with orbital periods of 50.2 and 8.1 days.

X-ray characterization of mesophases of human telomeric G-quadruplexes and other DNA analogues

DOE PAGES

Yasar, Selcuk; Schimelman, Jacob B.; Aksoyoglu, M. Alphan; ...

2016-06-02

We report that observed in the folds of guanine-rich oligonucleotides, non-canonical G-quadruplex structures are based on G-quartets formed by hydrogen bonding and cation-coordination of guanosines. In dilute 5'-guanosine monophosphate (GMP) solutions, G-quartets form by the self-assembly of four GMP nucleotides. We use x-ray diffraction to characterize the columnar liquid-crystalline mesophases in concentrated solutions of various model G-quadruplexes. We then probe the transitions between mesophases by varying the PEG solution osmotic pressure, thus mimicking in vivo molecular crowding conditions. Using the GMP-quadruplex, built by the stacking of G-quartets with no covalent linking between them, as the baseline, we report the liquid-crystallinemore » phase behaviors of two other related G-quadruplexes: (i) the intramolecular parallel-stranded G-quadruplex formed by the 22-mer four-repeat human telomeric sequence AG 3 (TTAG 3) 3 and (ii) the intermolecular parallel-stranded G-quadruplex formed by the TG(4)T oligonucleotides. Finally, we compare the mesophases of the G-quadruplexes, under PEG-induced crowding conditions, with the corresponding mesophases of the canonical duplex and triplex DNA analogues.« less

X-ray characterization of mesophases of human telomeric G-quadruplexes and other DNA analogues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yasar, Selcuk; Schimelman, Jacob B.; Aksoyoglu, M. Alphan

We report that observed in the folds of guanine-rich oligonucleotides, non-canonical G-quadruplex structures are based on G-quartets formed by hydrogen bonding and cation-coordination of guanosines. In dilute 5'-guanosine monophosphate (GMP) solutions, G-quartets form by the self-assembly of four GMP nucleotides. We use x-ray diffraction to characterize the columnar liquid-crystalline mesophases in concentrated solutions of various model G-quadruplexes. We then probe the transitions between mesophases by varying the PEG solution osmotic pressure, thus mimicking in vivo molecular crowding conditions. Using the GMP-quadruplex, built by the stacking of G-quartets with no covalent linking between them, as the baseline, we report the liquid-crystallinemore » phase behaviors of two other related G-quadruplexes: (i) the intramolecular parallel-stranded G-quadruplex formed by the 22-mer four-repeat human telomeric sequence AG 3 (TTAG 3) 3 and (ii) the intermolecular parallel-stranded G-quadruplex formed by the TG(4)T oligonucleotides. Finally, we compare the mesophases of the G-quadruplexes, under PEG-induced crowding conditions, with the corresponding mesophases of the canonical duplex and triplex DNA analogues.« less

The effect of the cation substitution on the structural and vibrational properties of Cs2NaGaxSc1-xF6 solid solution

NASA Astrophysics Data System (ADS)

Doriguetto, A. C.; Boschi, T. M.; Pizani, P. S.; Mascarenhas, Y. P.; Ellena, J.

2004-08-01

Raman scattering and x-ray diffration were used to characterize the structural and vibrational properties of the Cs2NaGaxSc1-xF6 solid solutions, for x ranging from 0.0 to 1.0. The Raman spectra, taken at room and low temperature, allow us to follow the phase evolution in detail and indicate the breaking of the local symmetry since low Ga concentration levels. Five compositions were studied by x-ray diffraction: x=0.0, 0.2, 0.5, 0.8, and 1.0. A cubic space group, Fm3¯m, was found to x=0.0 and x=0.2 and a trigonal one was found to x=0.5, 0.8, and 1.0. Details of both phases are presented and the correlation between x-ray diffraction and Raman scattering is discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Seo Hyoung; Kim, Jungho; Phatak, Charudatta

The interaction between X-rays and matter is an intriguing topic for both fundamental science and possible applications. In particular, synchrotron-based brilliant X-ray beams have been used as a powerful diagnostic tool to unveil nanoscale phenomena in functional materials. But, it has not been widely investigated how functional materials respond to the brilliant X-rays. Here, we report the X-ray-induced reversible resistance change in 40-nm-thick TiO 2 films sandwiched by Pt top and bottom electrodes, and propose the physical mechanism behind the emergent phenomenon. Our findings indicate that there exists a photovoltaic-like effect, which modulates the resistance reversibly by a few ordersmore » of magnitude, depending on the intensity of impinging X-rays. Furthermore, we found that this effect, combined with the X-ray irradiation induced phase transition confirmed by transmission electron microscopy, triggers a nonvolatile reversible resistance change. In understanding X-ray-controlled reversible resistance changes we can provide possibilities to control initial resistance states of functional materials, which could be useful for future information and energy storage devices.« less

Effect of X-ray irradiation on the optical absorption of СdSe1-xTex nanocrystals embedded in borosilicate glass

NASA Astrophysics Data System (ADS)

Prymak, M. V.; Azhniuk, Yu. M.; Solomon, A. M.; Krasilinets, V. M.; Lopushansky, V. V.; Bodnar, I. V.; Gomonnai, A. V.; Zahn, D. R. T.

2012-07-01

The effect of X-ray irradiation on the optical absorption spectra of CdSe1-xTex nanocrystals embedded in a borosilicate matrix is studied. The observed blue shift of the absorption edge and bleaching of the confinement-related features in the spectra are related to X-ray induced negative ionization of the nanocrystals with charge transfer across the nanocrystal/matrix interface. The radiation-induced changes are observed to recover after longer post-irradiation storage at room temperature.

Simultaneous scanning tunneling microscopy and synchrotron X-ray measurements in a gas environment.

PubMed

Mom, Rik V; Onderwaater, Willem G; Rost, Marcel J; Jankowski, Maciej; Wenzel, Sabine; Jacobse, Leon; Alkemade, Paul F A; Vandalon, Vincent; van Spronsen, Matthijs A; van Weeren, Matthijs; Crama, Bert; van der Tuijn, Peter; Felici, Roberto; Kessels, Wilhelmus M M; Carlà, Francesco; Frenken, Joost W M; Groot, Irene M N

2017-11-01

A combined X-ray and scanning tunneling microscopy (STM) instrument is presented that enables the local detection of X-ray absorption on surfaces in a gas environment. To suppress the collection of ion currents generated in the gas phase, coaxially shielded STM tips were used. The conductive outer shield of the coaxial tips can be biased to deflect ions away from the tip core. When tunneling, the X-ray-induced current is separated from the regular, 'topographic' tunneling current using a novel high-speed separation scheme. We demonstrate the capabilities of the instrument by measuring the local X-ray-induced current on Au(1 1 1) in 800 mbar Ar. Copyright © 2017 Elsevier B.V. All rights reserved.

Optical birefringence imaging of x-ray excited lithium tantalate

DOE PAGES

Durbin, S. M.; Landcastle, A.; DiChiara, A.; ...

2017-08-04

X-ray absorption in lithium tantalate induces large, long-lived (~10 -5 s) optical birefringence, visualized via scanning optical polarimetry, likely arising from electrooptic coupling to x-ray induced electric fields. Similar birefringence measured from glass, sapphire, and quartz was two orders of magnitude weaker. This suggests that x-ray excited charges preferentially create ordered, aligned dipoles within the noncentrosymmetric unit cell of ferroelectric LiTaO 3, enhancing the electric field compared to more isotropic charge distributions in the other materials. In conclusion, time-resolved measurements show a prompt response on a picosecond time scale, which along with the long decay time suggest novel approaches tomore » optical detection of x-rays using ferroelectric materials.« less

Method And Apparatus For Detecting Chemical Binding

DOEpatents

Warner, Benjamin P.; Havrilla, George J.; Miller, Thomasin C.; Wells, Cyndi A.

2005-02-22

The method for screening binding between a target binder and potential pharmaceutical chemicals involves sending a solution (preferably an aqueous solution) of the target binder through a conduit to a size exclusion filter, the target binder being too large to pass through the size exclusion filter, and then sending a solution of one or more potential pharmaceutical chemicals (preferably an aqueous solution) through the same conduit to the size exclusion filter after target binder has collected on the filter. The potential pharmaceutical chemicals are small enough to pass through the filter. Afterwards, x-rays are sent from an x-ray source to the size exclusion filter, and if the potential pharmaceutical chemicals form a complex with the target binder, the complex produces an x-ray fluorescence signal having an intensity that indicates that a complex has formed.

Method and apparatus for detecting chemical binding

DOEpatents

Warner, Benjamin P [Los Alamos, NM; Havrilla, George J [Los Alamos, NM; Miller, Thomasin C [Los Alamos, NM; Wells, Cyndi A [Los Alamos, NM

2007-07-10

The method for screening binding between a target binder and potential pharmaceutical chemicals involves sending a solution (preferably an aqueous solution) of the target binder through a conduit to a size exclusion filter, the target binder being too large to pass through the size exclusion filter, and then sending a solution of one or more potential pharmaceutical chemicals (preferably an aqueous solution) through the same conduit to the size exclusion filter after target binder has collected on the filter. The potential pharmaceutical chemicals are small enough to pass through the filter. Afterwards, x-rays are sent from an x-ray source to the size exclusion filter, and if the potential pharmaceutical chemicals form a complex with the target binder, the complex produces an x-ray fluorescence signal having an intensity that indicates that a complex has formed.

Investigation of chemical vapour deposition diamond detectors by X-ray micro-beam induced current and X-ray micro-beam induced luminescence techniques

NASA Astrophysics Data System (ADS)

Olivero, P.; Manfredotti, C.; Vittone, E.; Fizzotti, F.; Paolini, C.; Lo Giudice, A.; Barrett, R.; Tucoulou, R.

2004-10-01

Tracking detectors have become an important ingredient in high-energy physics experiments. In order to survive the harsh detection environment of the large hadron collider (LHC), trackers need to have special properties. They must be radiation hard, provide fast collection of charge, be as thin as possible and remove heat from readout electronics. The unique properties of diamond allow it to fulfill these requirements. In this work we present an investigation of the charge transport and luminescence properties of "detector grade" artificial chemical vapour deposition (CVD) diamond devices developed within the CERN RD42 collaboration, performed by means of X-ray micro-beam induced current collection (XBICC) and X-ray micro-beam induced luminescence (XBIL) techniques. XBICC technique allows quantitative estimates of the transport parameters of the material to be evaluated and mapped with micrometric spatial resolution. In particular, the high resolution and sensitivity of the technique has allowed a quantitative study of the inhomogeneity of the charge transport parameter defined as the product of mobility and lifetime for both electron and holes. XBIL represents a technique complementary to ion beam induced luminescence (IBIL), which has already been used by our group, since X-ray energy loss profile in the material is different from that of MeV ions. X-ray induced luminescence maps have been performed simultaneously with induced photocurrent maps, to correlate charge transport and induced luminescence properties of diamond. Simultaneous XBICC and XBIL maps exhibit features of partial complementarity that have been interpreted on the basis of considerations on radiative and non-radiative recombination processes which compete with charge transport efficiency.

Measurement of the energy dependence of X-ray-induced decomposition of potassium chlorate.

PubMed

Pravica, Michael; Bai, Ligang; Sneed, Daniel; Park, Changyong

2013-03-21

We report the first measurements of the X-ray induced decomposition of KClO3 as a function of energy in two experiments. KClO3 was pressurized to 3.5 GPa and irradiated with monochromatic synchrotron X-rays ranging in energy from 15 to 35 keV in 5 keV increments. A systematic increase in the decomposition rate as the energy was decreased was observed, which agrees with the 1/E(3) trend for the photoelectric process, except at the lowest energy studied. A second experiment was performed to access lower energies (10 and 12 keV) using a beryllium gasket; suggesting an apparent resonance near 15 keV or 0.83 Ǻ maximizing the chemical decomposition rate. A third experiment was performed using KIO3 to ascertain the anionic dependence of the decomposition rate, which was observed to be far slower than in KClO3, suggesting that the O-O distance is the critical factor in chemical reactions. These results will be important for more efficiently initiating chemical decomposition in materials using selected X-ray wavelengths that maximize decomposition to aid useful hard X-ray-induced chemistry and contribute understanding of the mechanism of X-ray-induced decomposition of the chlorates.

Chemical Speciation and Bond Lengths of Organic Solutes by Core-Level Spectroscopy: pH and Solvent Influence on p -Aminobenzoic Acid

DOE PAGES

Stevens, Joanna S.; Gainar, Adrian; Suljoti, Edlira; ...

2015-03-18

Through X-ray absorption and emission spectroscopies, the chemical, electronic and structural properties of organic species in solution can be observed. Near-edge X-ray absorption fine structure (NEXAFS) and resonant inelastic X-ray scattering (RIXS) measurements at the nitrogen K-edge of para-aminobenzoic acid reveal both pH- and solvent-dependent variations in the ionisation potential (IP), 1s→π* resonances and HOMO–LUMO gap. These changes unequivocally identify the chemical species (neutral, cationic or anionic) present in solution. It is shown how this incisive chemical state sensitivity is further enhanced by the possibility of quantitative bond length determination, based on the analysis of chemical shifts in IPs andmore » σ* shape resonances in the NEXAFS spectra. Finally, this provides experimental access to detecting even minor variations in the molecular structure of solutes in solution, thereby providing an avenue to examining computational predictions of solute properties and solute–solvent interactions.« less

3D-analysis of plant microstructures: advantages and limitations of synchrotron X-ray microtomography

NASA Astrophysics Data System (ADS)

Matsushima, U.; Graf, W.; Zabler, S.; Manke, I.; Dawson, M.; Choinka, G.; Hilger, A.; Herppich, W. B.

2013-01-01

Synchrotron X-ray computer microtomography was used to analyze the microstructure of rose peduncles. Samples from three rose cultivars, differing in anatomy, were scanned to study the relation between tissue structure and peduncles mechanical strength. Additionally, chlorophyll fluorescence imaging and conventional light microscopy was applied to quantify possible irradiation-induced damage to plant physiology and tissue structure. The spatial resolution of synchrotron X-ray computer microtomography was sufficiently high to investigate the complex tissues of intact rose peduncles without the necessity of any preparation. However, synchrotron X-radiation induces two different types of damage on irradiated tissues. First, within a few hours after first X-ray exposure, there is a direct physical destruction of cell walls. In addition, a slow and delayed destruction of chlorophyll and, consequently, of photosynthetic activity occurred within hours/ days after the exposure. The results indicate that synchrotron X-ray computer microtomography is well suited for three-dimensional visualization of the microstructure of rose peduncles. However, in its current technique, synchrotron X-ray computer microtomography is not really non-destructive but induce tissue damage. Hence, this technique needs further optimization before it can be applied for time-series investigations of living plant materials

X-ray Raman spectroscopy of lithium-ion battery electrolyte solutions in a flow cell.

PubMed

Ketenoglu, Didem; Spiekermann, Georg; Harder, Manuel; Oz, Erdinc; Koz, Cevriye; Yagci, Mehmet C; Yilmaz, Eda; Yin, Zhong; Sahle, Christoph J; Detlefs, Blanka; Yavaş, Hasan

2018-03-01

The effects of varying LiPF 6 salt concentration and the presence of lithium bis(oxalate)borate additive on the electronic structure of commonly used lithium-ion battery electrolyte solvents (ethylene carbonate-dimethyl carbonate and propylene carbonate) have been investigated. X-ray Raman scattering spectroscopy (a non-resonant inelastic X-ray scattering method) was utilized together with a closed-circle flow cell. Carbon and oxygen K-edges provide characteristic information on the electronic structure of the electrolyte solutions, which are sensitive to local chemistry. Higher Li + ion concentration in the solvent manifests itself as a blue-shift of both the π* feature in the carbon edge and the carbonyl π* feature in the oxygen edge. While these oxygen K-edge results agree with previous soft X-ray absorption studies on LiBF 4 salt concentration in propylene carbonate, carbon K-edge spectra reveal a shift in energy, which can be explained with differing ionic conductivities of the electrolyte solutions.

Multiscale X-ray and Proton Imaging of Bismuth-Tin Solidification

NASA Astrophysics Data System (ADS)

Gibbs, P. J.; Imhoff, S. D.; Morris, C. L.; Merrill, F. E.; Wilde, C. H.; Nedrow, P.; Mariam, F. G.; Fezzaa, K.; Lee, W.-K.; Clarke, A. J.

2014-08-01

The formation of structural patterns during metallic solidification is complex and multiscale in nature, ranging from the nanometer scale, where solid-liquid interface properties are important, to the macroscale, where casting mold filling and intended heat transfer are crucial. X-ray and proton imaging can directly interrogate structure, solute, and fluid flow development in metals from the microscale to the macroscale. X-rays permit high spatio-temporal resolution imaging of microscopic solidification dynamics in thin metal sections. Similarly, high-energy protons permit imaging of mesoscopic and macroscopic solidification dynamics in large sample volumes. In this article, we highlight multiscale x-ray and proton imaging of bismuth-tin alloy solidification to illustrate dynamic measurement of crystal growth rates and solute segregation profiles that can be that can be acquired using these techniques.

About microcracking due to leaching in cementitious composites: X-ray microtomography description and numerical approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rougelot, Thomas; Burlion, Nicolas, E-mail: nicolas.burlion@polytech-lille.f; Bernard, Dominique

2010-02-15

Chemical shock of cement based materials leads to significant degradation of their physical properties. A typical scenario is a calcium leaching due to water (water with very low pH compared with that of pore fluid). The main objective of this paper is to evaluate the evolution of microstructure induced by leaching of a cementitious composite using synchrotron X-ray micro tomography, mainly from an experimental point of view. In this particular case, it was possible to identify cracking induced by leaching. After a description of the degradation mechanism and the X-ray synchrotron microtomographic analysis, numerical simulations are performed in order tomore » show that cracking is induced by an initial pre-stressing of the composite, coupled with decalcification shrinkage and dramatic decrease in tensile strength during leaching. X-ray microtomography analysis allowed to make evidence of an induced microcracking in cementitious material submitted to leaching.« less

X-ray photoelectron spectroscopic study of the interaction of xanthate with coal pyrite and mineral pyrite surfaces

NASA Astrophysics Data System (ADS)

Khan, S. U. M.; Baltrus, J. P.; Lai, R. W.; Richardson, A. G.

1991-06-01

Coal pyrite and mineral pyrite surfaces were examined by X-ray photoelectron spectroscopy (XPS) before and after treatment in acidic and basic solutions of sodium ethyl xanthate (NaEtX). XPS showed that the degree of oxidation of coal and mineral pyrite surfaces increased when these pyrites were conditioned in basic solutions. However, conditioning in acidic solutions led to partial removal of surface oxidation from the pyrites. Addition of NaEtX to the acidic and basic solutions enhanced the removal of oxidation from pyrite surfaces. Pretreatment with sulfur dioxide further enhanced the removal of surface oxidation in the presence of NaEtX. Surface oxidation was typically less on mineral pyrite than coal pyrite surfaces following identical treatments. The flotation recoveries of the pyrites in the presence of NaEtX are greatest for the pyrites with the least amount of surface oxidation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Tengda; Li, Xiuling; Jang, Jin, E-mail: jjang@khu.ac.kr

Major obstacles towards power efficient complementary electronics employing oxide thin-film transistors (TFTs) lie in the lack of equivalent well performing p-channel devices. Here, we report a significant performance enhancement of solution-processed p-type nickel oxide (NiO{sub x}) TFTs by introducing Sn dopant. The Sn-doped NiO{sub x} (Sn-NiO{sub x}) TFTs annealed at 280 °C demonstrate substantially improved electrical performances with the increase in the on/off current ratio (I{sub on}/I{sub off}) by ∼100 times, field-effect mobility (μ{sub lin}) by ∼3 times, and the decrease in subthreshold swing by half, comparing with those of pristine NiO{sub x} TFTs. X-ray photoelectron spectroscopy and X-ray diffraction resultsmore » confirm that Sn atoms tend to substitute Ni sites and induce more amorphous phase. A decrease in density of states in the gap of NiO{sub x} by Sn doping and the shift of Fermi level (E{sub F}) into the midgap lead to the improvements of TFT performances. As a result, Sn-NiO{sub x} can be a promising material for the next-generation, oxide-based electronics.« less

Comprehensive Experimental and Computational Spectroscopic Study of Hexacyanoferrate Complexes in Water: From Infrared to X-ray Wavelengths.

PubMed

Ross, Matthew; Andersen, Amity; Fox, Zachary W; Zhang, Yu; Hong, Kiryong; Lee, Jae-Hyuk; Cordones, Amy; March, Anne Marie; Doumy, Gilles; Southworth, Stephen H; Marcus, Matthew A; Schoenlein, Robert W; Mukamel, Shaul; Govind, Niranjan; Khalil, Munira

2018-05-17

We present a joint experimental and computational study of the hexacyanoferrate aqueous complexes at equilibrium in the 250 meV to 7.15 keV regime. The experiments and the computations include the vibrational spectroscopy of the cyanide ligands, the valence electronic absorption spectra, and Fe 1s core hole spectra using element-specific-resonant X-ray absorption and emission techniques. Density functional theory-based quantum mechanics/molecular mechanics molecular dynamics simulations are performed to generate explicit solute-solvent configurations, which serve as inputs for the spectroscopy calculations of the experiments spanning the IR to X-ray wavelengths. The spectroscopy simulations are performed at the same level of theory across this large energy window, which allows for a systematic comparison of the effects of explicit solute-solvent interactions in the vibrational, valence electronic, and core-level spectra of hexacyanoferrate complexes in water. Although the spectroscopy of hexacyanoferrate complexes in solution has been the subject of several studies, most of the previous works have focused on a narrow energy window and have not accounted for explicit solute-solvent interactions in their spectroscopy simulations. In this work, we focus our analysis on identifying how the local solvation environment around the hexacyanoferrate complexes influences the intensity and line shape of specific spectroscopic features in the UV/vis, X-ray absorption, and valence-to-core X-ray emission spectra. The identification of these features and their relationship to solute-solvent interactions is important because hexacyanoferrate complexes serve as model systems for understanding the photochemistry and photophysics of a large class of Fe(II) and Fe(III) complexes in solution.

A new endstation at the Swiss Light Source for ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy measurements of liquid solutions.

PubMed

Brown, Matthew A; Redondo, Amaia Beloqui; Jordan, Inga; Duyckaerts, Nicolas; Lee, Ming-Tao; Ammann, Markus; Nolting, Frithjof; Kleibert, Armin; Huthwelker, Thomas; Müächler, Jean-Pierre; Birrer, Mario; Honegger, Juri; Wetter, Reto; Wörner, Hans Jakob; van Bokhoven, Jeroen A

2013-07-01

A new liquid microjet endstation designed for ultraviolet (UPS) and X-ray (XPS) photoelectron, and partial electron yield X-ray absorption (XAS) spectroscopies at the Swiss Light Source is presented. The new endstation, which is based on a Scienta HiPP-2 R4000 electron spectrometer, is the first liquid microjet endstation capable of operating in vacuum and in ambient pressures up to the equilibrium vapor pressure of liquid water at room temperature. In addition, the Scienta HiPP-2 R4000 energy analyzer of this new endstation allows for XPS measurements up to 7000 eV electron kinetic energy that will enable electronic structure measurements of bulk solutions and buried interfaces from liquid microjet samples. The endstation is designed to operate at the soft X-ray SIM beamline and at the tender X-ray Phoenix beamline. The endstation can also be operated using a Scienta 5 K ultraviolet helium lamp for dedicated UPS measurements at the vapor-liquid interface using either He I or He II α lines. The design concept, first results from UPS, soft X-ray XPS, and partial electron yield XAS measurements, and an outlook to the potential of this endstation are presented.

Assessment study of ion-exchange chromatography combined with solution X-ray scattering measurement for protein characterization.

PubMed

Watanabe, Yasushi

2018-03-02

The performance of ion-exchange chromatography combined with small-angle X-ray scattering measurement was evaluated by characterization of the hen egg white lysozyme as a model protein. The X-ray transmittance was estimated using a micro-ionization chamber equipped with a sample cell holder for the real-time monitoring of the X-ray beam strength through the salt gradient elution. The radius of gyration of the eluted protein was estimated to be 1.50 ± 0.06 (n = 3) nm and 1.4 ± 0.1 nm as the value at the zero protein concentration. By using the X-ray transmittance values for the scattering intensity correction, the molecular weight of the eluted protein was estimated to be 15,200 ± 500 (n = 3) and 14,400 ± 200 as the value at the zero protein concentration. These values are close to those of the monomer of this protein. The ion-exchange chromatography combined with the small-angle X-ray scattering measurement system equipped with the X-ray transmittance monitor is a reliable method for protein characterization in solution. Copyright © 2018 Elsevier B.V. All rights reserved.

Atomic study on the ordered structure in Al melts induced by liquid/substrate interface with Ti solute

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, H. L.; Han, Y. F., E-mail: yfhan@sjtu.edu.cn, E-mail: bdsun@sjtu.edu.cn; Zhou, W.

2015-01-26

Atomic ordering in Al melts induced by liquid/substrate interface with Ti solute was investigated by ab initio molecular dynamics simulations and in-situ synchrotron X-ray diffraction. It is predicted that deformed nanoscale ordering Al layers with a rhombohedral-centered hexagonal structure (R3{sup ¯}m space group) instead of the intrinsic fcc structure (Fm3{sup ¯}m space group) form on substrate at temperature above Al liquids. With Al atoms stacking away from the interface, the ordering structure reaches a critical thickness, which inhibits the consecutive stacking of Al atoms on substrates. The locally stacking reconstruction induced by Ti atom relieves the accumulated elastic strain energymore » in ordered Al layers, facilitating fully heterogeneous nucleation on substrate beyond the deformed ordering Al layer around the melting point. The roles of liquid/substrate interface with Ti solute in the physical behavior of heterogeneous nucleation on substrate were discussed.« less

Cybersecurity, massive data processing, community interaction, and other developments at WWW-based computational X-ray Server

NASA Astrophysics Data System (ADS)

Stepanov, Sergey

2013-03-01

X-Ray Server (x-server.gmca.aps.anl.gov) is a WWW-based computational server for modeling of X-ray diffraction, reflection and scattering data. The modeling software operates directly on the server and can be accessed remotely either from web browsers or from user software. In the later case the server can be deployed as a software library or a data fitting engine. As the server recently surpassed the milestones of 15 years online and 1.5 million calculations, it accumulated a number of technical solutions that are discussed in this paper. The developed approaches to detecting physical model limits and user calculations failures, solutions to spam and firewall problems, ways to involve the community in replenishing databases and methods to teach users automated access to the server programs may be helpful for X-ray researchers interested in using the server or sharing their own software online.

Novel applications of diagnostic x-rays in activating photo-agents through x-ray induced visible luminescence from rare-earth particles: an in vitro study

NASA Astrophysics Data System (ADS)

Abliz, Erkinay; Collins, Joshua E.; Friedberg, Joseph S.; Kumar, Ajith; Bell, Howard; Waynant, Ronald W.; Tata, Darrell B.

2010-02-01

Photodynamic agents such as Photofrin II (Photo II) utilized in photodynamic therapy (PDT) possess a remarkable property to become preferentially retained within the tumor's micro-environment. Upon the photo-agent's activation through visible light photon absorption, the agents exert their cellular cytotoxicity through type II and type I mechanistic pathways through extensive generation of reactive oxygen species (ROS): singlet oxygen 1O2, superoxide anion O2 -, and hydrogen peroxide H2O2, within the intratumoral environment. Unfortunately, due to shallow visible light penetration depth (~2mm to 5mm) in tissues, the PDT strategy currently has largely been restricted to the treatments of surface tumors, such as the melanomas. Additional invasive strategies through optical fibers are currently utilized in getting the visible light into the intended deep seated targets within the body for PDT. In this communication, we report on a novel strategy in utilizing "soft" energy diagnostic X-rays to indirectly activate Photo II through X-ray induced luminescence from Gadolinium oxysulfide (20 micron dimension) particles doped with Terbium: Gd2O2S:Tb. X-ray induced visible luminescence from Gd2O2S:Tb particles was spectroscopically characterized and the ROS production levels from clinically relevant concentration (10 μg/ml) of Photo II was quantified through changes in the Vitamin C absorbance. ROS kinetics through X-ray induced luminescence was found to be similar to the ROS kinetics from red He-Ne laser exposures used in the clinics. Taken together, in-vitro findings herein provide the basis for future studies in determining the safety and efficacy of this non-invasive X-ray induced luminescence strategy in activating photo-agent in deep seated tumors.

Hand x-ray

MedlinePlus

... this page: //medlineplus.gov/ency/article/003811.htm Hand x-ray To use the sharing features on ... Duplication for commercial use must be authorized in writing by ADAM Health Solutions. About MedlinePlus Site Map ...

Irreversible metal-insulator transition in thin film VO2 induced by soft X-ray irradiation

NASA Astrophysics Data System (ADS)

Singh, V. R.; Jovic, V.; Valmianski, I.; Ramirez, J. G.; Lamoureux, B.; Schuller, Ivan K.; Smith, K. E.

2017-12-01

In this study, we show the ability of soft x-ray irradiation to induce room temperature metal-insulator transitions (MITs) in VO2 thin films grown on R-plane sapphire. The ability of soft x-rays to induce MIT in VO2 thin films is confirmed by photoemission spectroscopy and soft x-ray spectroscopy measurements. When irradiation was discontinued, the systems do not return to the insulating phase. Analysis of valence band photoemission spectra revealed that the density of states (DOSs) of the V 3d band increased with irradiation time, while the DOS of the O 2p band decreased. We use these results to propose a model in which the MIT is driven by oxygen desorption from thin films during irradiation.

Energy dispersive X-ray fluorescence determination of cadmium in uranium matrix using Cd Kα line excited by continuum

NASA Astrophysics Data System (ADS)

Dhara, Sangita; Misra, N. L.; Aggarwal, S. K.; Venugopal, V.

2010-06-01

An energy dispersive X-ray fluorescence method for determination of cadmium (Cd) in uranium (U) matrix using continuum source of excitation was developed. Calibration and sample solutions of cadmium, with and without uranium were prepared by mixing different volumes of standard solutions of cadmium and uranyl nitrate, both prepared in suprapure nitric acid. The concentration of Cd in calibration solutions and samples was in the range of 6 to 90 µg/mL whereas the concentration of Cd with respect to U ranged from 90 to 700 µg/g of U. From the calibration solutions and samples containing uranium, the major matrix uranium was selectively extracted using 30% tri-n-butyl phosphate in dodecane. Fixed volumes (1.5 mL) of aqueous phases thus obtained were taken directly in specially designed in-house fabricated leak proof Perspex sample cells for the energy dispersive X-ray fluorescence measurements and calibration plots were made by plotting Cd Kα intensity against respective Cd concentration. For the calibration solutions not having uranium, the energy dispersive X-ray fluorescence spectra were measured without any extraction and Cd calibration plots were made accordingly. The results obtained showed a precision of 2% (1 σ) and the results deviated from the expected values by < 4% on average.

A multi-scale Lattice Boltzmann model for simulating solute transport in 3D X-ray micro-tomography images of aggregated porous materials

NASA Astrophysics Data System (ADS)

Zhang, Xiaoxian; Crawford, John W.; Flavel, Richard J.; Young, Iain M.

2016-10-01

The Lattice Boltzmann (LB) model and X-ray computed tomography (CT) have been increasingly used in combination over the past decade to simulate water flow and chemical transport at pore scale in porous materials. Because of its limitation in resolution and the hierarchical structure of most natural soils, the X-ray CT tomography can only identify pores that are greater than its resolution and treats other pores as solid. As a result, the so-called solid phase in X-ray images may in reality be a grey phase, containing substantial connected pores capable of conducing fluids and solute. Although modified LB models have been developed to simulate fluid flow in such media, models for solute transport are relatively limited. In this paper, we propose a LB model for simulating solute transport in binary soil images containing permeable solid phase. The model is based on the single-relaxation time approach and uses a modified partial bounce-back method to describe the resistance caused by the permeable solid phase to chemical transport. We derive the relationship between the diffusion coefficient and the parameter introduced in the partial bounce-back method, and test the model against analytical solution for movement of a pulse of tracer. We also validate it against classical finite volume method for solute diffusion in a simple 2D image, and then apply the model to a soil image acquired using X-ray tomography at resolution of 30 μm in attempts to analyse how the ability of the solid phase to diffuse solute at micron-scale affects the behaviour of the solute at macro-scale after a volumetric average. Based on the simulated results, we discuss briefly the danger in interpreting experimental results using the continuum model without fully understanding the pore-scale processes, as well as the potential of using pore-scale modelling and tomography to help improve the continuum models.

Reaction Heterogeneity in LiNi 0.8 Co 0.15 Al 0.05 O 2 Induced by Surface Layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grenier, Antonin; Liu, Hao; Wiaderek, Kamila M.

2017-08-15

Through operando synchrotron powder X-ray diffraction (XRD) analysis of layered transition metal oxide electrodes of composition LiNi0.8Co0.15Al0.05O2 (NCA), we decouple the intrinsic bulk reaction mechanism from surface-induced effects. For identically prepared and cycled electrodes stored in different environments, we demonstrate that the intrinsic bulk reaction for pristine NCA follows solid-solution mechanism, not a two-phase as suggested previously. By combining high resolution powder X-ray diffraction, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and surface sensitive X-ray photoelectron spectroscopy (XPS), we demonstrate that adventitious Li2CO3 forms on the electrode particle surface during exposure to air, through reaction with atmospheric CO2. This surfacemore » impedes ionic and electronic transport to the underlying electrode, with progressive erosion of this layer during cycling giving rise to different reaction states in particles with an intact vs an eroded Li2CO3 surface-coating. This reaction heterogeneity, with a bimodal distribution of reaction states, has previously been interpreted as a “two-phase” reaction mechanism for NCA, as an activation step that only occurs during the first cycle. Similar surface layers may impact the reaction mechanism observed in other electrode materials using bulk probes such as operando powder XRD.« less

Magnetostatic focal spot correction for x-ray tubes operating in strong magnetic fields using iterative optimization

PubMed Central

Lillaney, Prasheel; Shin, Mihye; Conolly, Steven M.; Fahrig, Rebecca

2012-01-01

Purpose: Combining x-ray fluoroscopy and MR imaging systems for guidance of interventional procedures has become more commonplace. By designing an x-ray tube that is immune to the magnetic fields outside of the MR bore, the two systems can be placed in close proximity to each other. A major obstacle to robust x-ray tube design is correcting for the effects of the magnetic fields on the x-ray tube focal spot. A potential solution is to design active shielding that locally cancels the magnetic fields near the focal spot. Methods: An iterative optimization algorithm is implemented to design resistive active shielding coils that will be placed outside the x-ray tube insert. The optimization procedure attempts to minimize the power consumption of the shielding coils while satisfying magnetic field homogeneity constraints. The algorithm is composed of a linear programming step and a nonlinear programming step that are interleaved with each other. The coil results are verified using a finite element space charge simulation of the electron beam inside the x-ray tube. To alleviate heating concerns an optimized coil solution is derived that includes a neodymium permanent magnet. Any demagnetization of the permanent magnet is calculated prior to solving for the optimized coils. The temperature dynamics of the coil solutions are calculated using a lumped parameter model, which is used to estimate operation times of the coils before temperature failure. Results: For a magnetic field strength of 88 mT, the algorithm solves for coils that consume 588 A/cm2. This specific coil geometry can operate for 15 min continuously before reaching temperature failure. By including a neodymium magnet in the design the current density drops to 337 A/cm2, which increases the operation time to 59 min. Space charge simulations verify that the coil designs are effective, but for oblique x-ray tube geometries there is still distortion of the focal spot shape along with deflections of approximately 3 mm in the radial and circumferential directions on the anode. Conclusions: Active shielding is an attractive solution for correcting the effects of magnetic fields on the x-ray focal spot. If extremely long fluoroscopic exposure times are required, longer operation times can be achieved by including a permanent magnet with the active shielding design. PMID:22957623

Flow method and apparatus for screening chemicals using micro x-ray fluorescence

DOEpatents

Warner, Benjamin P [Los Alamos, NM; Havrilla, George J [Los Alamos, NM; Miller, Thomasin C [Bartlesville, OK; Lewis, Cris [Los Alamos, NM; Mahan, Cynthia A [Los Alamos, NM; Wells, Cyndi A [Los Alamos, NM

2009-04-14

Method and apparatus for screening chemicals using micro x-ray fluorescence. A method for screening a mixture of potential pharmaceutical chemicals for binding to at least one target binder involves flow-separating a solution of chemicals and target binders into separated components, exposing them to an x-ray excitation beam, detecting x-ray fluorescence signals from the components, and determining from the signals whether or not a binding event between a chemical and target binder has occurred.

Flow method and apparatus for screening chemicals using micro x-ray fluorescence

DOEpatents

Warner, Benjamin P [Los Alamos, NM; Havrilla, George J [Los Alamos, NM; Miller, Thomasin C [Bartlesville, OK; Lewis, Cris [Los Alamos, NM; Mahan, Cynthia A [Los Alamos, NM; Wells, Cyndi A [Los Alamos, NM

2011-04-26

Method and apparatus for screening chemicals using micro x-ray fluorescence. A method for screening a mixture of potential pharmaceutical chemicals for binding to at least one target binder involves flow separating a solution of chemicals and target binders into separated components, exposing them to an x-ray excitation beam, detecting x-ray fluorescence signals from the components, and determining from the signals whether or not a binding event between a chemical and target binder has occurred.

Low-temperature synthesis of homogeneous solid solutions of scheelite-structured Ca 1-xSr xWO 4 and Sr 1-xBa xWO 4 nanocrystals

DOE PAGES

Culver, Sean P.; Greaney, Matthew J.; Tinoco, Antonio; ...

2015-07-24

Here, a series of compositionally complex scheelite-structured nanocrystals of the formula A 1-xA’ xWO 4 (A = Ca, Sr, Ba) have been prepared under benign synthesis conditions using the vapor diffusion sol–gel method. Discrete nanocrystals with sub-20 nm mean diameters were obtained after kinetically controlled hydro- lysis and polycondensation at room temperature, followed by composition-dependent thermal aging at or below 60 °C. Rietveld analysis of X-ray diffraction data and Raman spectroscopy verified the synthesis of continuous and phase-pure nanocrystal solid solutions across the entire composition space for A 1-xA’ xWO 4, where 0 ≤ x ≤ 1. Elemental analysis bymore » X-ray photoelectron and inductively coupled plasma- atomic emission spectroscopies demonstrated excellent agreement between the nominal and experi- mentally determined elemental stoichiometries, while energy dispersive X-ray spectroscopy illustrated good spatial elemental homogeneity within these nanocrystals synthesized under benign conditions.« less

A method of measuring gold nanoparticle concentrations by x-ray fluorescence for biomedical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu Di; Li Yuhua; Wong, Molly D.

Purpose: This paper reports a technique that enables the quantitative determination of the concentration of gold nanoparticles (GNPs) through the accurate detection of their fluorescence radiation in the diagnostic x-ray spectrum. Methods: Experimentally, x-ray fluorescence spectra of 1.9 and 15 nm GNP solutions are measured using an x-ray spectrometer, individually and within chicken breast tissue samples. An optimal combination of excitation and emission filters is determined to segregate the fluorescence spectra at 66.99 and 68.80 keV from the background scattering. A roadmap method is developed that subtracts the scattered radiation (acquired before the insertion of GNP solutions) from the signalmore » radiation acquired after the GNP solutions are inserted. Results: The methods effectively minimize the background scattering in the spectrum measurements, showing linear relationships between GNP solutions from 0.1% to 10% weight concentration and from 0.1% to 1.0% weight concentration inside a chicken breast tissue sample. Conclusions: The investigation demonstrated the potential of imaging gold nanoparticles quantitatively in vivo for in-tissue studies, but future studies will be needed to investigate the ability to apply this method to clinical applications.« less

X-ray Spectrometry.

ERIC Educational Resources Information Center

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

1984-01-01

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

Aplanatic telescopes based on Schwarzschild optical configuration: from grazing incidence Wolter-like x-ray optics to Cherenkov two-mirror normal incidence telescopes

NASA Astrophysics Data System (ADS)

Sironi, Giorgia

2017-09-01

At the beginning of XX century Karl Schwarzschild defined a method to design large-field aplanatic telescopes based on the use of two aspheric mirrors. The approach was then refined by Couder (1926) who, in order to correct for the astigmatic aberration, introduced a curvature of the focal plane. By the way, the realization of normal-incidence telescopes implementing the Schwarzschild aplanatic configuration has been historically limited by the lack of technological solutions to manufacture and test aspheric mirrors. On the other hand, the Schwarzschild solution was recovered for the realization of coma-free X-ray grazing incidence optics. Wolter-like grazing incidence systems are indeed free of spherical aberration, but still suffer from coma and higher order aberrations degrading the imaging capability for off-axis sources. The application of the Schwarzschild's solution to X-ray optics allowed Wolter to define an optical system that exactly obeys the Abbe sine condition, eliminating coma completely. Therefore these systems are named Wolter-Schwarzschild telescopes and have been used to implement wide-field X-ray telescopes like the ROSAT WFC and the SOHO X-ray telescope. Starting from this approach, a new class of X-ray optical system was proposed by Burrows, Burg and Giacconi assuming polynomials numerically optimized to get a flat field of view response and applied by Conconi to the wide field x-ray telescope (WFXT) design. The Schwarzschild-Couder solution has been recently re-discovered for the application to normal-incidence Cherenkov telescopes, thanks to the suggestion by Vassiliev and collaborators. The Italian Institute for Astrophysics (INAF) realized the first Cherenkov telescope based on the polynomial variation of the Schwarzschild configuration (the so-called ASTRI telescope). Its optical qualification was successfully completed in 2016, demonstrating the suitability of the Schwarzschild-like configuration for the Cherenkov astronomy requirements. Moreover, other Cherenkov telescopes based on Schwarzschild-Couder solutions are currently being completed at Fred Lawrence Whipple Observatory in southern Arizona, USA and at the Observatoire de Paris-Meudon. In this paper we will review the Karl Schwarzschild solution and its application to grazing incidence and Cherenkov telescopes, discussing on future applications in the field of high-energy astronomy.

Spectral analysis of paramagnetic centers induced in human tooth enamel by x-rays and gamma radiation

NASA Astrophysics Data System (ADS)

Kirillov, V. A.; Kuchuro, I. I.

2010-03-01

Based on study of spectral and relaxation characteristics, we have established that paramagnetic centers induced in tooth enamel by x-rays and gamma radiation are identical in nature. We show that for the same exposure dose, the intensity of the electron paramagnetic resonance (EPR) signal induced by x-radiation with effective energy 34 keV is about an order of magnitude higher than the amplitude of the signal induced by gamma radiation. We have identified a three-fold attenuation of the EPR signal along the path of the x-radiation from the buccal to the lingual side of a tooth, which is evidence that the individual had undergone diagnostic x-ray examination of the dentition or skull. We have shown that the x-ray exposure doses reconstructed from the EPR spectra are an order of magnitude higher than the applied doses, while the dose loads due to gamma radiation are equal to the applied doses. The data obtained indicate that for adequate reconstruction of individual absorbed doses from EPR spectra of tooth enamel in the population subjected to the combined effect of x-radiation and accidental external gamma radiation as a result of the disaster at the Chernobyl nuclear power plant, we need to take into account the contribution to the dose load from diagnostic x-rays in examination of the teeth, jaw, or skull.

Studies in useful hard x-ray induced chemistry

NASA Astrophysics Data System (ADS)

Pravica, Michael; Bai, Ligang; Sneed, Daniel; Park, Changyong

2013-06-01

The observed rapid decomposition of potassium chlorate (via 2KClO3 + h ν --> 2KCl +3O2) via synchrotron hard x-ray irradiation (>10 keV) has enabled experiments that are developing novel and useful hard x-ray chemistry. We have observed a number of radiation-induced in situ decomposition reactions in various substances which release O2, H2, N2, NH3, and H2O in a diamond anvil cell (DAC) at ambient and high pressures. These novel acatalytic and isothermal reactions represent a highly controllable, penetrating, and focused method to initiate chemistry (including x-ray induced combustion) in sealed and/or isolated chambers which maintain matter under extreme conditions. During our studies, we have typically observed a slowing of decomposition with pressure including phase dependent decomposition of KClO3. Energy dependent studies have observed an apparent resonance near 15 keV at which the decomposition rate is maximized. This may enable use of much lower flux and portable x-ray sources (e.g. x-ray tubes) in larger scale experiments. These developments support novel means to load DACs and control chemical reactions providing novel routes of synthesis of novel materials under extreme conditions.

Plasma-induced graft-polymerization of polyethylene glycol acrylate on polypropylene substrates

NASA Astrophysics Data System (ADS)

Zanini, S.; Orlandi, M.; Colombo, C.; Grimoldi, E.; Riccardi, C.

2009-08-01

A detailed study of argon plasma-induced graft-polymerization of polyethylene glycol acrylate (PEGA) on polypropylene (PP) substrates (membranes and films) is presented. The process consists of four steps: (a) plasma pre-activation of the PP substrates; (b) immersion in a PEGA solution; (c) argon plasma-induced graft-polymerization; (d) washing and drying of the samples. Influence of the solution and plasma parameters on the process efficiency evaluated in terms of amount of grafted polymer, coverage uniformity and substrates wettability, are investigated. The plasma-induced graft-polymerization of PEGA is then followed by sample weighting, water droplet adsorption time and contact angle measurements, attenuated total reflection infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) analyses. The stability of the obtained thin films was evaluated in water and in phosphate buffer saline (PBS) at 37 °C. Results clearly indicates that plasma-induced graft-polymerization of PEGA is a practical methodology for anti-fouling surface modification of materials.

Small-angle solution scattering using the mixed-mode pixel array detector.

PubMed

Koerner, Lucas J; Gillilan, Richard E; Green, Katherine S; Wang, Suntao; Gruner, Sol M

2011-03-01

Solution small-angle X-ray scattering (SAXS) measurements were obtained using a 128 × 128 pixel X-ray mixed-mode pixel array detector (MMPAD) with an 860 µs readout time. The MMPAD offers advantages for SAXS experiments: a pixel full-well of >2 × 10(7) 10 keV X-rays, a maximum flux rate of 10(8) X-rays pixel(-1) s(-1), and a sub-pixel point-spread function. Data from the MMPAD were quantitatively compared with data from a charge-coupled device (CCD) fiber-optically coupled to a phosphor screen. MMPAD solution SAXS data from lysozyme solutions were of equal or better quality than data captured by the CCD. The read-noise (normalized by pixel area) of the MMPAD was less than that of the CCD by an average factor of 3.0. Short sample-to-detector distances were required owing to the small MMPAD area (19.2 mm × 19.2 mm), and were revealed to be advantageous with respect to detector read-noise. As predicted by the Shannon sampling theory and confirmed by the acquisition of lysozyme solution SAXS curves, the MMPAD at short distances is capable of sufficiently sampling a solution SAXS curve for protein shape analysis. The readout speed of the MMPAD was demonstrated by continuously monitoring lysozyme sample evolution as radiation damage accumulated. These experiments prove that a small suitably configured MMPAD is appropriate for time-resolved solution scattering measurements.

Small-angle solution scattering using the mixed-mode pixel array detector

PubMed Central

Koerner, Lucas J.; Gillilan, Richard E.; Green, Katherine S.; Wang, Suntao; Gruner, Sol M.

2011-01-01

Solution small-angle X-ray scattering (SAXS) measurements were obtained using a 128 × 128 pixel X-ray mixed-mode pixel array detector (MMPAD) with an 860 µs readout time. The MMPAD offers advantages for SAXS experiments: a pixel full-well of >2 × 107 10 keV X-rays, a maximum flux rate of 108 X-rays pixel−1 s−1, and a sub-pixel point-spread function. Data from the MMPAD were quantitatively compared with data from a charge-coupled device (CCD) fiber-optically coupled to a phosphor screen. MMPAD solution SAXS data from lysozyme solutions were of equal or better quality than data captured by the CCD. The read-noise (normalized by pixel area) of the MMPAD was less than that of the CCD by an average factor of 3.0. Short sample-to-detector distances were required owing to the small MMPAD area (19.2 mm × 19.2 mm), and were revealed to be advantageous with respect to detector read-noise. As predicted by the Shannon sampling theory and confirmed by the acquisition of lysozyme solution SAXS curves, the MMPAD at short distances is capable of sufficiently sampling a solution SAXS curve for protein shape analysis. The readout speed of the MMPAD was demonstrated by continuously monitoring lysozyme sample evolution as radiation damage accumulated. These experiments prove that a small suitably configured MMPAD is appropriate for time-resolved solution scattering measurements. PMID:21335900

SAD phasing of a structure based on cocrystallized iodides using an in-house Cu Kalpha X-ray source: effects of data redundancy and completeness on structure solution.

PubMed

Yogavel, Manickam; Gill, Jasmita; Mishra, Prakash Chandra; Sharma, Amit

2007-08-01

Superoxide dismutase (SOD) from Potentilla atrosanguinea (Wall. ex. Lehm.) was crystallized using 20% PEG 3350 and 0.2 M ammonium iodide and diffraction data were collected to 2.36 A resolution using an in-house Cu Kalpha X-ray source. Analyses show that data with a redundancy of 3.2 were sufficient to determine the structure by the SAD technique using the iodine anomalous signal. This redundancy is lower than that in previous cases in which protein structures were determined using iodines for phasing and in-house copper X-ray sources. Cocrystallization of proteins with halide salts such as ammonium iodide in combination with copper-anode X-ray radiation can therefore serve as a powerful and easy avenue for structure solution.

Synchrotron x-ray modification of nanoparticle superlattice formation

NASA Astrophysics Data System (ADS)

Lu, Chenguang; Akey, Austin J.; Herman, Irving P.

2012-09-01

The synchrotron x-ray radiation used to perform small angle x-ray scattering (SAXS) during the formation of three-dimensional nanoparticle superlattices by drop casting nanoparticle solutions affects the structure and the local crystalline order of the resulting films. The domain size decreases due to the real-time SAXS analysis during drying and more macroscopic changes are visible to the eye.

DOE Office of Scientific and Technical Information (OSTI.GOV)

X Li; Y Mao; H Ma

An ionic liquid (IL) 1-docosanyl-3-methylimidazolium bromide was incorporated into ultra-high molecular weight polyethylene (UHMWPE) and formed IL/UHMWPE blends by solution mixing. The structure evolution of these blends during uniaxial stretching was followed by in-situ synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. During deformation at room temperature, deformation-induced phase transformation from orthorhombic to monoclinic phase was observed in both IL/UHMWPE blends and neat UHMWPE. The elongation-to-break ratios of IL/UHMWPE blends were found to increase by 2-3 times compared with that of pure UHMWPE, while the tensile strength remained about the same. In contrast, during deformation at highmore » temperature (120 C), no phase transformation was observed. However, the blend samples showed much better toughness, higher crystal orientation and higher tilting extent of lamellar structure at high strains.« less

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography.

PubMed

Gicquel, Yannig; Schubert, Robin; Kapis, Svetlana; Bourenkov, Gleb; Schneider, Thomas; Perbandt, Markus; Betzel, Christian; Chapman, Henry N; Heymann, Michael

2018-04-24

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The devices are patterned from epoxy glue using soft lithography and are suitable for in situ X-ray diffraction experiments at room temperature. The sample wells are lidded on both sides with polymeric polyimide foil windows that allow diffraction data collection with low X-ray background. This fabrication method is undemanding and inexpensive. After the sourcing of a SU-8 master wafer, all fabrication can be completed outside of a cleanroom in a typical research lab environment. The chip design and fabrication protocol utilize capillary valving to microfluidically split an aqueous reaction into defined nanoliter sized droplets. This loading mechanism avoids the sample loss from channel dead-volume and can easily be performed manually without using pumps or other equipment for fluid actuation. We describe how isolated nanoliter sized drops of protein solution can be monitored in situ by dynamic light scattering to control protein crystal nucleation and growth. After suitable crystals are grown, complete X-ray diffraction datasets can be collected using goniometer based in situ fixed target serial X-ray crystallography at room temperature. The protocol provides custom scripts to process diffraction datasets using a suite of software tools to solve and refine the protein crystal structure. This approach avoids the artefacts possibly induced during cryo-preservation or manual crystal handling in conventional crystallography experiments. We present and compare three protein structures that were solved using small crystals with dimensions of approximately 10-20 µm grown in chip. By crystallizing and diffracting in situ, handling and hence mechanical disturbances of fragile crystals is minimized. The protocol details how to fabricate a custom X-ray transparent microfluidic chip suitable for in situ serial crystallography. As almost every crystal can be used for diffraction data collection, these microfluidic chips are a very efficient crystal delivery method.

Simulation tools for analyzer-based x-ray phase contrast imaging system with a conventional x-ray source

NASA Astrophysics Data System (ADS)

Caudevilla, Oriol; Zhou, Wei; Stoupin, Stanislav; Verman, Boris; Brankov, J. G.

2016-09-01

Analyzer-based X-ray phase contrast imaging (ABI) belongs to a broader family of phase-contrast (PC) X-ray imaging modalities. Unlike the conventional X-ray radiography, which measures only X-ray absorption, in PC imaging one can also measures the X-rays deflection induced by the object refractive properties. It has been shown that refraction imaging provides better contrast when imaging the soft tissue, which is of great interest in medical imaging applications. In this paper, we introduce a simulation tool specifically designed to simulate the analyzer-based X-ray phase contrast imaging system with a conventional polychromatic X-ray source. By utilizing ray tracing and basic physical principles of diffraction theory our simulation tool can predicting the X-ray beam profile shape, the energy content, the total throughput (photon count) at the detector. In addition we can evaluate imaging system point-spread function for various system configurations.

Analysis of radiation-induced small Cu particle cluster formation in aqueous CuCl2

USGS Publications Warehouse

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

2001-01-01

Radition-induced small Cu particle cluster formation in aqueous CuCl2 was analyzed. It was noticed that nearest neighbor distance increased with the increase in the time of irradiation. This showed that the clusters approached the lattice dimension of bulk copper. As the average cluster size approached its bulk dimensions, an increase in the nearest neighbor coordination number was found with the decrease in the surface to volume ratio. Radiolysis of water by incident x-ray beam led to the reduction of copper ions in the solution to themetallic state.

Structural, morphological and Raman studies on hybridized PVDF/BaTiO3 nanocomposites

NASA Astrophysics Data System (ADS)

Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.

2017-05-01

Hybridized nanocomposites of polyvinylidene fluoride (PVDF) and nano - barium titanate (BaTiO3) were prepared using the solution casting method for different concentrations of nano-BaTiO3 and were characterized by X-ray diffraction and scanning electron microscopy. The flower like structure for morphology was observed in SEM. Raman analysis showed that the modified BaTiO3 particles, due to higher specific surfaces, induce, predominantly, the crystallization of the electrically active β-phase of PVDF, while the initial micron size particles induce the formation of the most common but non-polar α-crystal form.

Role of the chemical substitution on the luminescence properties of solid solutions Ca{sub (1−x)}Cd{sub (x)}WO{sub 4} (0 ≤ x ≤1)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taoufyq, A.; Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir; CEA, DEN, Département d'Etudes des Réacteurs, Service de Physique Expérimentale, Laboratoire Dosimétrie Capteurs Instrumentation, 13108 Saint-Paul-lez-Durance

2015-10-15

Highlights: • Luminescence can be modified by chemical substitution in solid solutions Ca{sub 1−x}Cd{sub x}WO{sub 4}. • The various emission spectra (charge transfer) were obtained under X-ray excitation. • Scheelite or wolframite solid solutions presented two types of emission spectra. • A luminescence component depended on cadmium substitution in each solid solution. • A component was only characteristic of oxyanion symmetry in each solid solution. - Abstract: We have investigated the chemical substitution effects on the luminescence properties under X-ray excitation of the solid solutions Ca{sub (1−x)}Cd{sub (x)}WO{sub 4} with 0 ≤ x ≤ 1. Two types of wide spectralmore » bands, associated with scheelite-type or wolframite-type solid solutions, have been observed at room temperature. We decomposed each spectral band into several spectral components characterized by energies and intensities varying with composition x. One Gaussian component was characterized by an energy decreasing regularly with the composition x, while the other Gaussian component was only related to the tetrahedral or octahedral configurations of tungstate groups WO{sub 4}{sup 2−} or WO{sub 6}{sup 6−}. The luminescence intensities exhibited minimum values in the composition range x < 0.5 corresponding to scheelite-type structures, then, they regularly increased for cadmium compositions x > 0.5 corresponding to wolframite-type structures.« less

Friction-induced structural transformations of the carbide phase in Hadfield steel

NASA Astrophysics Data System (ADS)

Korshunov, L. G.; Sagaradze, V. V.; Chernenko, N. L.; Shabashov, V. A.

2015-08-01

Structural transformations of the carbide phase in Hadfield steel (110G13) that occur upon plastic deformation by dry sliding friction have been studied by methods of optical metallography, X-ray diffraction, and transmission electron microscopy. Deformation is shown to lead to the refinement of the particles of the carbide phase (Fe, Mn)3C to a nanosized level. The effect of the deformation-induced dissolution of (Fe, Mn)3C carbides in austenite of 110G13 (Hadfield) steel has been revealed, which manifests in the appearance of new lines belonging to austenite with an unusually large lattice parameter ( a = 0.3660-0.3680 nm) in the X-ray diffraction patterns of steel tempered to obtain a fine-lamellar carbide phase after deformation. This austenite is the result of the deformation-induced dissolution of disperse (Fe, Mn)3C particles, which leads to the local enrichment of austenite with carbon and manganese. The tempering that leads to the formation of carbide particles in 110G13 steel exerts a negative influence on the strain hardening of the steel, despite the increase in the hardness of steel upon tempering and the development of the processes of the deformation-induced dissolution of the carbide phase, which leads to the strengthening of the γ solid solution.

The X-Ray Counterpart to LAT PSR J2021+4026 and Its Interesting Spectrum

NASA Technical Reports Server (NTRS)

Weisskopf, Martin C.; Becker, W.; Carraminana, A.; De Luca, A.; Dormandy, M.; Harding, A.; Kanbach, G.; O'Dell, S. L.; Parkinson, P. Saz; Ray, P.;

Influence of Sn doping in BaSnxTi1-xO3 ceramics on microstructural and dielectric properties

NASA Astrophysics Data System (ADS)

Ansari, Mohd. Azaj; Sreenivas, K.

2018-05-01

BaSnxTi1-x O3 solid solutions with varying Sn content (x = 0.00, 0.05, 0.15, 0.25) prepared by solid state reaction method have been studied for their structural and dielectric properties. X-ray diffraction and Raman spectroscopic analysis show composition induced modifications in the crystallographic structure, and with increasing Sn content the structure changes from tetragonal to cubic structure. The tetragonal distortion decreases with increasing Sn, and the structure becomes purely cubic for x =0.25. Changes in the structure are reflected in the temperature dependent dielectric properties. For increasing Sn content the peak dielectric constant is found to increase and the phase transition temperature (Tc) decreases to lower temperature. The purely cubic structure with x=0.25 shows a diffused phased transition.

In vitro simulation studies of silica deposition induced by lignin from rice*

PubMed Central

Fang, Jiang-Yu; Ma, Xue-Long

2006-01-01

To reveal the possible mechanism of silica deposition in higher plants, lignin was isolated from rice straw following a modified method to conduct a simulation experiment in vitro. UV and infrared absorption spectra showed that the substance had the unique characteristics of pure lignin. The presence of silicon in the precipitation was revealed by TEM (transmission electron microscopy) with EDXA (energy dispersive X-ray analysis) device. It was found that in the borax solution where lignin precipitation occurred silica-lignin co-precipitation was produced but not in the DMSO solution where lignin was broken into its composition compounds and did not precipitate. This means that it is macromolecular lignin itself but not its compounds that could induce silica deposition in higher plants. PMID:16532527

X-ray targeted bond or compound destruction

DOEpatents

Pravica, Sr., Michael G.

2016-11-01

This document provides methods, systems, and devices for inducing a decomposition reaction by directing x-rays towards a location including a particular compound. The x-rays can have an irradiation energy that corresponds to a bond distance of a bond in the particular compound in order to break that bond and induce a decomposition of that particular compound. In some cases, the particular compound is a hazardous substance or part of a hazardous substance. In some cases, the particular compound is delivered to a desired location in an organism and x-rays induce a decomposition reaction that creates a therapeutic substance (e.g., a toxin that kills cancer cells) in the location of the organism. In some cases, the particular compound decomposes to produce a reactant in a reactor apparatus (e.g., fuel cell or semiconductor fabricator).

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiselev, M. A., E-mail: elena@jinr.ru; Zemlyanaya, E. V.; Zhabitskaya, E. I.

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.

X-Ray Crystallography Reagent

NASA Technical Reports Server (NTRS)

Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

2003-01-01

Microcapsules prepared by encapsulating an aqueous solution of a protein, drug or other bioactive substance inside a semi-permeable membrane by are disclosed. The microcapsules are formed by interfacial coacervation under conditions where the shear forces are limited to 0-100 dynes per square centimeter at the interface. By placing the microcapsules in a high osmotic dewatering solution. the protein solution is gradually made saturated and then supersaturated. and the controlled nucleation and crystallization of the protein is achieved. The crystal-filled microcapsules prepared by this method can be conveniently harvested and stored while keeping the encapsulated crystals in essentially pristine condition due to the rugged. protective membrane. Because the membrane components themselves are x-ray transparent, large crystal-containing microcapsules can be individually selected, mounted in x-ray capillary tubes and subjected to high energy x-ray diffraction studies to determine the 3-D smucture of the protein molecules. Certain embodiments of the microcapsules of the invention have composite polymeric outer membranes which are somewhat elastic, water insoluble, permeable only to water, salts, and low molecular weight molecules and are structurally stable in fluid shear forces typically encountered in the human vascular system.

Simultaneous use of solution NMR and X-ray data in REFMAC5 for joint refinement/detection of structural differences.

PubMed

Rinaldelli, Mauro; Ravera, Enrico; Calderone, Vito; Parigi, Giacomo; Murshudov, Garib N; Luchinat, Claudio

2014-04-01

The program REFMAC5 from CCP4 was modified to allow the simultaneous use of X-ray crystallographic data and paramagnetic NMR data (pseudocontact shifts and self-orientation residual dipolar couplings) and/or diamagnetic residual dipolar couplings. Incorporation of these long-range NMR restraints in REFMAC5 can reveal differences between solid-state and solution conformations of molecules or, in their absence, can be used together with X-ray crystallographic data for structural refinement. Since NMR and X-ray data are complementary, when a single structure is consistent with both sets of data and still maintains reasonably `ideal' geometries, the reliability of the derived atomic model is expected to increase. The program was tested on five different proteins: the catalytic domain of matrix metalloproteinase 1, GB3, ubiquitin, free calmodulin and calmodulin complexed with a peptide. In some cases the joint refinement produced a single model consistent with both sets of observations, while in other cases it indicated, outside the experimental uncertainty, the presence of different protein conformations in solution and in the solid state.

Characterization of Sb-doped Bi(2)UO(6) solid solutions by X-ray diffraction and X-ray absorption spectroscopy.

PubMed

Misra, N L; Yadav, A K; Dhara, Sangita; Mishra, S K; Phatak, Rohan; Poswal, A K; Jha, S N; Sinha, A K; Bhattacharyya, D

2013-01-01

The preparation and characterization of Sb-doped Bi(2)UO(6) solid solutions, in a limited composition range, is reported for the first time. The solid solutions were prepared by solid-state reactions of Bi(2)O(3), Sb(2)O(3) and U(3)O(8) in the required stoichiometry. The reaction products were characterized by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) measurements at the Bi and U L(3) edges. The XRD patterns indicate the precipitation of additional phases in the samples when Sb doping exceeds 4 at%. The chemical shifts of the Bi absorption edges in the samples, determined from the XANES spectra, show a systematic variation only up to 4 at% of Sb doping and support the results of XRD measurements. These observations are further supported by the local structure parameters obtained by analysis of the EXAFS spectra. The local structure of U is found to remain unchanged upon Sb doping indicating that Sb(+3) ions replace Bi(+3) during the doping of Bi(2)UO(6) by Sb.

Complexation of polyoxometalates with cyclodextrins.

PubMed

Wu, Yilei; Shi, Rufei; Wu, Yi-Lin; Holcroft, James M; Liu, Zhichang; Frasconi, Marco; Wasielewski, Michael R; Li, Hui; Stoddart, J Fraser

2015-04-01

Although complexation of hydrophilic guests inside the cavities of hydrophobic hosts is considered to be unlikely, we demonstrate herein the complexation between γ- and β-cyclodextrins (γ- and β-CDs) with an archetypal polyoxometalate (POM)--namely, the [PMo12O40](3-) trianion--which has led to the formation of two organic-inorganic hybrid 2:1 complexes, namely [La(H2O)9]{[PMo12O40]⊂[γ-CD]2} (CD-POM-1) and [La(H2O)9] {[PMo12O40]⊂[β-CD]2} (CD-POM-2), in the solid state. The extent to which these complexes assemble in solution has been investigated by (i) (1)H, (13)C, and (31)P NMR spectroscopies and (ii) small- and wide-angle X-ray scattering, as well as (iii) mass spectrometry. Single-crystal X-ray diffraction reveals that both complexes have a sandwich-like structure, wherein one [PMo12O40](3-) trianion is encapsulated by the primary faces of two CD tori through intermolecular [C-H···O═Mo] interactions. X-ray crystal superstructures of CD-POM-1 and CD-POM-2 show also that both of these 2:1 complexes are lined up longitudinally in a one-dimensional columnar fashion by means of [O-H···O] interactions. A beneficial nanoconfinement-induced stabilizing effect is supported by the observation of slow color changes for these supermolecules in aqueous solution phase. Electrochemical studies show that the redox properties of [PMo12O40](3-) trianions encapsulated by CDs in the complexes are largely preserved in solution. The supramolecular complementarity between the CDs and the [PMo12O40](3-) trianion provides yet another opportunity for the functionalization of POMs under mild conditions by using host-guest chemistry.

Adjustable Grazing-Incidence X-Ray Optics

NASA Technical Reports Server (NTRS)

O'Dell, Stephen L.; Reid, Paul B.

2015-01-01

With its unique subarcsecond imaging performance, NASA's Chandra X-ray Observatory illustrates the importance of fine angular resolution for x-ray astronomy. Indeed, the future of x-ray astronomy relies upon x-ray telescopes with comparable angular resolution but larger aperture areas. Combined with the special requirements of nested grazing-incidence optics, mass, and envelope constraints of space-borne telescopes render such advances technologically and programmatically challenging. The goal of this technology research is to enable the cost-effective fabrication of large-area, lightweight grazing-incidence x-ray optics with subarcsecond resolution. Toward this end, the project is developing active x-ray optics using slumped-glass mirrors with thin-film piezoelectric arrays for correction of intrinsic or mount-induced distortions.

Sputter deposition of PZT piezoelectric films on thin glass substrates for adjustable x-ray optics.

PubMed

Wilke, Rudeger H T; Johnson-Wilke, Raegan L; Cotroneo, Vincenzo; Davis, William N; Reid, Paul B; Schwartz, Daniel A; Trolier-McKinstry, Susan

2013-05-10

Piezoelectric PbZr(0.52)Ti(0.48)O(3) (PZT) thin films deposited on thin glass substrates have been proposed for adjustable optics in future x-ray telescopes. The light weight of these x-ray optics enables large collecting areas, while the capability to correct mirror figure errors with the PZT thin film will allow much higher imaging resolution than possible with conventional lightweight optics. However, the low strain temperature and flexible nature of the thin glass complicate the use of chemical-solution deposition due to warping of the substrate at typical crystallization temperatures for the PZT. RF magnetron sputtering enabled preparation of PZT films with thicknesses up to 3 μm on Schott D263 glass substrates with much less deformation. X-ray diffraction analysis indicated that the films crystallized with the perovskite phase and showed no indication of secondary phases. Films with 1 cm(2) electrodes exhibited relative permittivity values near 1100 and loss tangents below 0.05. In addition, the remanent polarization was 26 μC/cm(2) with coercive fields of 33 kV/cm. The transverse piezoelectric coefficient was as high as -6.1±0.6 C/m(2). To assess influence functions for the x-ray optics application, the piezoelectrically induced deflection of individual cells was measured and compared with finite-element-analysis calculations. The good agreement between the results suggests that actuation of PZT thin films can control mirror figure errors to a precision of about 5 nm, allowing sub-arcsecond imaging.

Wind collisions in three massive stars of Cygnus OB2

NASA Astrophysics Data System (ADS)

Cazorla, Constantin; Nazé, Yaël; Rauw, Gregor

2014-01-01

Aims: We wish to study the origin of the X-ray emission of three massive stars in the Cyg OB2 association: Cyg OB2 #5, Cyg OB2 #8A, and Cyg OB2 #12. Methods: To this aim, dedicated X-ray observations from XMM-Newton and Swift are used, as well as archival ROSAT and Suzaku data. Results: Our results on Cyg OB2 #8A improve the phase coverage of the orbit and confirm previous studies: the signature of a wind-wind collision is conspicuous. In addition, signatures of a wind-wind collision are also detected in Cyg OB2 #5, but the X-ray emission appears to be associated with the collision between the inner binary and the tertiary component orbiting it with a 6.7 yr period, without a putative collision inside the binary. The X-ray properties strongly constrain the orbital parameters, notably allowing us to discard some proposed orbital solutions. To improve the knowledge of the orbit, we revisit the light curves and radial velocity of the inner binary, looking for reflex motion induced by the third star. Finally, the X-ray emission of Cyg OB2 #12 is also analyzed. It shows a marked decrease in recent years, compatible with either a wind-wind collision in a wide binary or the aftermath of a recent eruption. Based on observations collected at the Observatoire de Haute Provence (OHP) as well as with Swift and XMM-Newton.Tables 1-3 and 5 are available in electronic form at http://www.aanda.org

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

USGS Publications Warehouse

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, L. X.; Zhang, X.; Lockard, J. V.

Transient molecular structures along chemical reaction pathways are important for predicting molecular reactivity, understanding reaction mechanisms, as well as controlling reaction pathways. During the past decade, X-ray transient absorption spectroscopy (XTA, or LITR-XAS, laser-initiated X-ray absorption spectroscopy), analogous to the commonly used optical transient absorption spectroscopy, has been developed. XTA uses a laser pulse to trigger a fundamental chemical process, and an X-ray pulse(s) to probe transient structures as a function of the time delay between the pump and probe pulses. Using X-ray pulses with high photon flux from synchrotron sources, transient electronic and molecular structures of metal complexes havemore » been studied in disordered media from homogeneous solutions to heterogeneous solution-solid interfaces. Several examples from the studies at the Advanced Photon Source in Argonne National Laboratory are summarized, including excited-state metalloporphyrins, metal-to-ligand charge transfer (MLCT) states of transition metal complexes, and charge transfer states of metal complexes at the interface with semiconductor nanoparticles. Recent developments of the method are briefly described followed by a future prospective of XTA. It is envisioned that concurrent developments in X-ray free-electron lasers and synchrotron X-ray facilities as well as other table-top laser-driven femtosecond X-ray sources will make many breakthroughs and realise dreams of visualizing molecular movies and snapshots, which ultimately enable chemical reaction pathways to be controlled.« less

Resonant Soft X-ray Scattering as a Powerful Probe of Buried Polymer Interfaces

NASA Astrophysics Data System (ADS)

Chen, Wei; Jiang, Zhang; Tirrell, Matthew

Elucidation of polymer interfacial structures provides insights into interfacial molecular mechanisms for coating protection, adhesion, lubrication, friction, wettability, biocompatibility, and even charge transport properties. Resonant Soft X-ray Scattering (RSoXS) offers a unique element, site and valence specific probe to study spatial modulations of molecular orbital degrees of freedom on the nanoscopic length scale. This unique sensitivity is achieved by merging small angle x-ray scattering and x-ray absorption spectroscopy into a single experiment, where the scattering provides information about spatial modulations and the spectroscopy provides sensitivity to the molecular anisotropy. Here we applied RSoXS to polystyrene (PS) films at solid-solid interfaces and poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) brushes at solid-liquid interfaces. It is found that the interfacial width of PS thin film is about one order of magnitude large than those observed by traditional scattering techniques. In addition, although the ion-induced changes of PMPC thickness are not apparent in aqueous solutions, their chain conformations like polyzwitterion distribution and correlation varied, dependent on salt types, ionic strengths and ion valences. Consequently, it is evident that RSoXS is a powerful probe of buried polymer interlaces with both spatial and chemical sensitivities. This work was supported by the U.S. Department of Energy, Office of Science, Program in Basic Energy Sciences, Division of Materials Science and Engineering.

Irradiation with x-rays of the energy 18 MV induces radioactivity in transfusion blood: Proposal of a safe method using 6 MV.

PubMed

Frentzel, Katharina; Badakhshi, Harun

2016-12-01

To prevent a fatal transfusion-associated graft-versus-host disease, it is recommended to irradiate transfusion blood and blood components with ionizing radiation. Using x-rays from a linear accelerator of the radiotherapy department is an accepted alternative to gamma irradiation devices of the blood bank and to the orthovoltage units that are replacing the gamma irradiators today. However, the use of high energy x-rays may carry a potential risk of induced radioactivity. The objective of this study was to investigate the effect of two different energy levels, 6 and 18 MV, which are executed in routine clinical settings. The research question was if induced radioactivity occurs at one of these standard energy levels. The authors aimed to give a proposal for a blood irradiation procedure that certainly avoids induced radioactivity. For this study, the authors developed a blood bag phantom, irradiated it with x-ray energies of 6 and 18 MV, and measured the induced radioactivity in a well counter. Thereafter, the same irradiation and measuring procedure was performed with a unit of packed red blood cells. A feasible clinical procedure was developed using 6 MV and an acrylic box. With the irradiation planning system XiO, the authors generated an irradiation protocol for the linear accelerator Siemens ONCOR Anvant-Garde. Both measurement setups showed that there was induced radioactivity for 18 MV but not for 6 MV. The induced radioactivity for 18 MV was up to 190 times the background. This is significant and of clinical relevance especially since there are newborn and fetal blood recipients for whom every radiation exposure has to be strictly avoided. The irradiation of blood with x-rays from a linear accelerator of the radiotherapy department is safe and feasible, but by the current state of scientific knowledge, the authors recommend to use an x-ray energy of 6 MV or less to avoid induced radioactivity in transfusion blood.

Observation of glassy state relaxation during annealing of frozen sugar solutions by X-ray computed tomography.

PubMed

Nakagawa, Kyuya; Tamiya, Shinri; Do, Gabsoo; Kono, Shinji; Ochiai, Takaaki

2018-06-01

Glassy phase formation in a frozen product determines various properties of the freeze-dried products. When an aqueous solution is subjected to freezing, a glassy phase forms as a consequence of freeze-concentration. During post-freezing annealing, the relaxation of the glassy phase and the ripening of ice crystals (i.e. Ostwald ripening) spontaneously occur, where the kinetics are controlled by the annealing and glass transition temperatures. This study was motivated to observe the progress of glassy state relaxation separate from ice coarsening during annealing. X-ray computed tomography (CT) was used to observe a frozen and post-freezing annealed solutions by using monochromatized X-ray from the synchrotron radiation. CT images were successfully obtained, and the frozen matrix were analyzed based on the gray level values that were equivalent to the linear X-ray attenuation coefficients of the observed matters. The CT images obtained from rapidly frozen sucrose and dextrin solutions with different concentrations gave clear linear relationships between the linear X-ray attenuation coefficients values and the solute concentrations. It was confirmed that the glassy state relaxation progressed as increasing annealing time, and this trend was larger in the order of the glass transition temperature of the maximally freeze-concentrated phase. The sucrose-water system required nearly 20 h of annealing time at -5 °C for the completion of the glassy phase relaxation, whereas dextrin-water systems required much longer periods because of their higher glass transition temperatures. The trends of ice coarsening, however, did not perfectly correspond to the trends of the relaxation, suggesting that the glassy phase relaxation and Ostwald ripening would jointly control the ice crystal growth/ripening kinetics, and the dominant mechanism differed by the annealing stage. Copyright © 2018 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shivananda, C. S.; Rao, B. Lakshmeesha; Madhukumar, R.

In this work silk fibroin/pullulan blend films have been prepared by solution casting method. The blend films were examined for structural, and thermal properties using X-ray diffraction (XRD), thermogravimatric (TGA) and differential scanning calorimetry (DSC) analysis. The XRD results indicate that with the introduction of pullulan, the interaction between SF and pullulan in the blend films induced the conformation transition of SF films and amorphous phase increases with increasing pullulan ratio. The thermal properties of the blend films were improved significantly in the blend films.

Ultrafast Independent N-H and N-C Bond Deformation Investigated with Resonant Inelastic X-Ray Scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eckert, Sebastian; Norell, Jesper; Miedema, Piter S.

Here, the femtosecond excited-state dynamics following resonant photoexcitation enable the selective deformation of N-H and N-C chemical bonds in 2-thiopyridone in aqueous solution with optical or X-ray pulses. In combination with multiconfigurational quantum-chemical calculations, the orbital-specific electronic structure and its ultrafast dynamics accessed with resonant inelastic X-ray scattering at the N 1s level using synchrotron radiation and the soft X-ray free-electron laser LCLS provide direct evidence for this controlled photoinduced molecular deformation and its ultrashort timescale.

Ultrafast Independent N-H and N-C Bond Deformation Investigated with Resonant Inelastic X-Ray Scattering

DOE PAGES

Eckert, Sebastian; Norell, Jesper; Miedema, Piter S.; ...

2017-04-04

Here, the femtosecond excited-state dynamics following resonant photoexcitation enable the selective deformation of N-H and N-C chemical bonds in 2-thiopyridone in aqueous solution with optical or X-ray pulses. In combination with multiconfigurational quantum-chemical calculations, the orbital-specific electronic structure and its ultrafast dynamics accessed with resonant inelastic X-ray scattering at the N 1s level using synchrotron radiation and the soft X-ray free-electron laser LCLS provide direct evidence for this controlled photoinduced molecular deformation and its ultrashort timescale.

Electrochemically Induced Insulator-Metal-Insulator Transformations of Vanadium Dioxide Nanocrystal Films

NASA Astrophysics Data System (ADS)

Milliron, Delia; Dahlman, Clayton; Leblanc, Gabriel; Bergerud, Amy

Vanadium dioxide (VO2) undergoes significant optical, electronic, and structural changes as it transforms between the low-temperature monoclinic and high-temperature rutile phases. The low-temperature state is insulating and transparent, while the high-temperature state is metallic and IR blocking. Alternative stimuli have been utilized to trigger insulator-to-metal transformations in VO2, including electrochemical gating. Here, VO2 nanocrystal films have been prepared by solution deposition of V2O3 nanocrystals followed by oxidative annealing. Nanocrystalline VO2 films are electrochemically reduced, inducing changes in their electronic and optical properties. We observe a reversible transition between infrared transparent insulating phases and a darkened metallic phase by in situ visible-near-infrared spectroelectrochemistry and correlate these observations with structural and electronic changes monitored by X-ray absorption spectroscopy, X-ray diffraction, Raman spectroscopy, and conductivity measurements. Reduction causes an initial transformation to a metallic, IR-colored distorted monoclinic phase. However, an unexpected reversible transition from conductive, reduced monoclinic VO2 to an infrared-transparent insulating phase is observed upon further reduction.

Room-temperature ferromagnetism in Fe-based perovskite solid solution in lead-free ferroelectric Bi0.5Na0.5TiO3 materials

NASA Astrophysics Data System (ADS)

Hung, Nguyen The; Bac, Luong Huu; Trung, Nguyen Ngoc; Hoang, Nguyen The; Van Vinh, Pham; Dung, Dang Duc

2018-04-01

The integration of ferromagnetism in lead-free ferroelectric materials is important to fabricate smart materials for electronic devices. In this work, (1 - x)Bi0.5Na0.5TiO3 + xMgFeO3-δ materials (x = 0-9 mol%) were prepared through sol-gel method. X-ray diffraction characterization indicated that MgFeO3-δ materials existed as a well solid solution in lead-free ferroelectric Bi0.5Na0.5TiO3 materials. The rhombohedral structure of Bi0.5Na0.5TiO3 materials was distorted due to the random distribution of Mg and Fe cations into the host lattice. The reduced optical band gap and the induced room-temperature ferromagnetism were due to the spin splitting of transition metal substitution at the B-site of perovskite Bi0.5Na0.5TiO3 and the modification by A-site co-substitution. This work elucidates the role of secondary phase as solid solution in Bi0.5Na0.5TiO3 material for development of lead-free multiferroelectric materials.

Exploring hardness enhancement in superhard tungsten tetraboride-based solid solutions using radial X-ray diffraction

DOE PAGES

Xie, Miao; Mohammadi, Reza; Turner, Christopher L.; ...

2015-07-29

In this paper, we explore the hardening mechanisms in WB4-based solid solutions upon addition of Ta, Mn, and Cr using in situ radial X-ray diffraction techniques under nonhydrostatic pressure. By examining the lattice-supported differential strain, we provide insights into the mechanism for hardness increase in binary solid solutions at low dopant concentrations. Speculations on the combined effects of electronic structure and atomic size in ternary WB 4 solid solutions containing Ta with Mn or Cr are also included to understand the extremely high hardness of these materials.

Low-energy proton induced M X-ray production cross sections for 70Yb, 81Tl and 82Pb

NASA Astrophysics Data System (ADS)

Shehla; Mandal, A.; Kumar, Ajay; Roy Chowdhury, M.; Puri, Sanjiv; Tribedi, L. C.

2018-07-01

The cross sections for production of Mk (k = Mξ, Mαβ, Mγ, Mm1) X-rays of 70Yb, 81Tl and 82Pb induced by 50-250 keV protons have been measured in the present work. The experimental cross sections have been compared with the earlier reported values and those calculated using the ionization cross sections based on the ECPSSR (Perturbed (P) stationary(S) state(S), incident ion energy (E) loss, Coulomb (C) deflection and relativistic (R) correction) model, the X-ray emission rates based on the Dirac-Fock model, the fluorescence and Coster-Kronig yields based on the Dirac-Hartree-Slater (DHS) model. In addition, the present measured proton induced X-ray production cross sections have also been compared with those calculated using the Dirac-Hartree-Slater (DHS) model based ionization cross sections and those based on the Plane wave Born Approximation (PWBA). The measured M X-ray production cross sections are, in general, found to be higher than the ECPSSR and DHS model based values and lower than the PWBA model based cross sections.

Proton Induced X-Ray Emission (PIXE): Determining the Concentration of Samples

NASA Astrophysics Data System (ADS)

McCarthy, Mallory; Rodriguez Manso, Alis; Pajouhafsar, Yasmin; J Yennello, Sherry

2017-09-01

We used Proton Induced X-ray Emission (PIXE) as an analysis technique to determine the composition of samples, in particular, the elemental constituents and the concentrations. Each of the samples are bombarded with protons, which in result displaces a lower level electron and causes a higher level electron to fall into its place. This displacement produces characteristic x-rays that are `fingerprints' for each element. The protons supplied for the bombardment are produced and accelerated by the K150 proton beam in the Cyclotron Institute at Texas A&M University. The products are detected by three x-ray detectors: XR-100CR Si-PIN, XR-100SDD, and XR-100T CdTe. The peaks of the spectrum are analyzed using a software analysis tool, GUPIXWIN, to determine the concentration of the known elements of each particular sample. The goals of this work are to test run the Proton Induced X-Ray Emission experimental set up at Texas A&M University (TAMU) and to determine the concentration of thin films containing KBr given by the TAMU Chemical Engineering Department.

Synthetic hydroxyapatites doped with Zn(II) studied by X-ray diffraction, infrared, Raman and thermal analysis

NASA Astrophysics Data System (ADS)

Guerra-López, José R.; Echeverría, Gustavo A.; Güida, Jorge A.; Viña, Raúl; Punte, Graciela

2015-06-01

Calcium hydroxyapatite (CaHap) formation when different amounts of Zn(II) are present in the mother solution has been investigated by atomic absorption, infrared and Raman spectroscopies, X-ray diffraction and thermal analysis (DTA and TG). The studied samples have been synthesized at T=95 °C and pH 9 in air. The analysis of the results have shown that the pure CaHap sample crystallizes in the monoclinic form P21/b. Concentrations up to 20% of Zn(II) in the mother solution, equivalent to smaller concentrations in solid (up to 9.1% in wt), favor the formation of the hexagonal apatite, P63/m, while Zn(II) concentrations higher than 20% in solution help an amorphous phase development where vibrational spectra indicated coexistence of two phases: an apatite and ZnNH4PO4·H2O. Infrared data of thermal treated samples endorse that HPO42- ion had not been incorporated in Zn(II) doped samples during the synthesis process. Present results also allow to conclude that Zn(II) cation exhibits a preference to occupy the Ca2 site of the apatite structure and induces water adsorption and a small quantity of CO32- cation incorporation, leading to formation of a less crystalline Ca deficient apatite.

The perfection and defect structure of organic hourglass inclusion K 2SO 4 crystals

NASA Astrophysics Data System (ADS)

Vetter, William M.; Totsuka, Hirono; Dudley, Michael; Kahr, Bart

2002-06-01

Hourglass inclusion crystals of K 2SO 4 were grown from aqueous solutions containing the dye acid fuchsin, and studied by synchrotron white-beam X-ray topography and reciprocal space mapping. Both self-nucleated and larger, seeded dye-included crystals were prepared, as well as comparable undoped crystals. While the dye modified the crystals' habit strongly, X-ray topographs showed it had no influence on their dislocation configurations, which were typical for solution-grown crystals. No kinematical contrast arising from the presence of the dye was observed that indicated dye-induced strain in the crystal lattice. Growth sector boundaries were visible in the dyed crystals but not in undoped crystals, implying there was a slightly higher lattice mismatch across growth sector boundaries in the dye-included crystals. Reciprocal space maps of small areas on an hourglass inclusion crystal within either a dye-included growth sector or an undoped growth sector showed single peaks with the same perfect crystal rocking curve width and no dilatation or tilt of the host lattice resulting from the dye's presence. These results showed hourglass inclusion crystals can be grown in which the presence of the dye disturbs the crystalline structure of the host salt minimally, and that hourglass inclusions have the nature of a solid solution.

Thermodynamic modeling of solid solutions between monosulfate and monochromate 3CaO Bullet Al{sub 2}O{sub 3} Bullet Ca[(CrO{sub 4}){sub x}(SO{sub 4}){sub 1-x}] Bullet nH{sub 2}O

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leisinger, Sabine M., E-mail: sabine.leisinger@eawag.ch; Institute of Biogeochemistry and Pollutant Dynamics, ETH, CH-8092 Zurich; Lothenbach, Barbara

2012-01-15

In hydrated cement paste AFm-phases are regarded to play an important role in the binding of the toxic contaminant chromate through isomorphic substitution with sulfate. Solid solutions formation can lower the solubility of the solids, thus reducing chromate leaching concentrations. Solid solutions between monosulfate and monochromate were synthesized and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX) and inductive coupled plasma optical emission spectroscopy (ICP-OES). Based on the measured ion concentrations in solution total solubility products of the solid solution series were determined. For pure monochromate a logK = - 28.4more » {+-} 0.7 was determined. Results from solid and solution analysis showed that limited solid solutions exist. Based on XRD diffractograms a solid solution with a miscibility gap 0.15 < Crx < 0.85 with a dimensionless Guggenheim parameter of 2.43 was proposed.« less

Liquid sample delivery techniques for serial femtosecond crystallography

PubMed Central

Weierstall, Uwe

2014-01-01

X-ray free-electron lasers overcome the problem of radiation damage in protein crystallography and allow structure determination from micro- and nanocrystals at room temperature. To ensure that consecutive X-ray pulses do not probe previously exposed crystals, the sample needs to be replaced with the X-ray repetition rate, which ranges from 120 Hz at warm linac-based free-electron lasers to 1 MHz at superconducting linacs. Liquid injectors are therefore an essential part of a serial femtosecond crystallography experiment at an X-ray free-electron laser. Here, we compare different techniques of injecting microcrystals in solution into the pulsed X-ray beam in vacuum. Sample waste due to mismatch of the liquid flow rate to the X-ray repetition rate can be addressed through various techniques. PMID:24914163

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunter, Mark S.; Yoon, Chun Hong; DeMirci, Hasan

Structural information about biological macromolecules near the atomic scale provides important insight into the functions of these molecules. To date, X-ray crystallography has been the predominant method used for macromolecular structure determination. However, challenges exist when solving structures with X-rays, including the phase problem and radiation damage. X-ray-free electron lasers (X-ray FELs) have enabled collection of diffraction information before the onset of radiation damage, yet the majority of structures solved at X-ray FELs have been phased using external information via molecular replacement. De novo phasing at X-ray FELs has proven challenging due in part to per-pulse variations in intensity andmore » wavelength. Here we report the solution of a selenobiotinyl-streptavidin structure using phases obtained by the anomalous diffraction of selenium measured at a single wavelength (Se-SAD) at the Linac Coherent Light Source. Finally, our results demonstrate Se-SAD, routinely employed at synchrotrons for novel structure determination, is now possible at X-ray FELs.« less

THE MULTIELEMENTAL ANALYSIS OF DRINKING WATER USING PROTON-INDUCED X-RAY EMISSION (PIXE)

EPA Science Inventory

A new, rapid, and economical method for the multielemental analysis of drinking water samples is described. The concentrations of 76 elements heavier than aluminum are determined using proton-induced x-ray emission (PIXE) technology. The concentration of sodium is evaluated using...

A graphite crystal polarimeter for stellar X-ray astronomy.

NASA Technical Reports Server (NTRS)

Weisskopf, M. C.; Berthelsdorf, R.; Epstein, G.; Linke, R.; Mitchell, D.; Novick, R.; Wolff, R. S.

1972-01-01

The first crystal X-ray polarimeter to be used for X-ray astronomy is described. Polarization is measured by modulation of the X rays diffracted at an average 45 deg glancing angle from large, curved graphite crystal panels as these rotate about an axis parallel to the incident X-ray flux. Arrangement of the crystal panels, the design of the detector, and the signal-processing circuitry were optimized to minimize systematic effects produced by off-axis pointing of the rocket and cosmic ray induced events. The in-flight performance of the instrument in relation to the observed background signal is discussed.

Effect of Cooling Rates on γ → α Transformation and Metastable States in Fe-Cu Alloys with Addition of Ni

NASA Astrophysics Data System (ADS)

Crozet, C.; Verdier, M.; Lay, S.; Antoni-Zdziobek, A.

2018-07-01

α/γ phase transformations occurring in Fe-10Cu-xNi alloys (0 ≤ x ≤ 15 in mass%) were studied using X-ray diffraction, scanning electron microscopy, electron back scattered diffraction, transmission electron microscopy and chemical analysis, combining X-ray microanalysis with energy dispersive spectrometry in the scanning electron microscope and electron microprobe analysis with wavelength dispersive spectrometry. The influence of cooling rate on the microstructure was investigated using ice-brine quenching and 2 °C/min slow cooling rate performed with dilatometry. Ni addition induces metastable transformations on cooling: massive and bainitic ferrite are formed depending on the alloy composition and cooling rate. Moreover, most of the Cu phase precipitates on cooling giving rise to a fine distribution of Cu particles in the ferrite grains. For both cooling conditions, the hardness increases with increasing Ni content and a higher hardness is obtained in the quenched alloy for each composition. The change in hardness is correlated to the effect of Ni solid solution, transformation structure and size of Cu particles.

THz pulse doubler at FLASH: double pulses for pump–probe experiments at X-ray FELs

PubMed Central

Zapolnova, Ekaterina; Golz, Torsten; Pan, Rui; Klose, Karsten; Stojanovic, Nikola

2018-01-01

FLASH, the X-ray free-electron laser in Hamburg, Germany, employs a narrowband high-field accelerator THz source for unique THz pump X-ray probe experiments. However, the large difference in optical paths of the THz and X-ray beamlines prevents utilization of the machine’s full potential (e.g. extreme pulse energies in the soft X-ray range). To solve this issue, lasing of double electron bunches, separated by 28 periods of the driving radiofrequency (at 1.3 GHz), timed for the temporal overlap of THz and X-ray pulses at the experimental station has been employed. In order to optimize conditions for a typical THz pump X-ray probe experiment, X-ray lasing of the first bunch to one-sixth of that of the second has been suppressed. Finally, synchronization of THz radiation pulses was measured to be ∼20 fs (r.m.s.), and a solution for monitoring the arrival time for achieving higher temporal resolution is presented. PMID:29271749

Selenium single-wavelength anomalous diffraction de novo phasing using an X-ray-free electron laser

DOE PAGES

Hunter, Mark S.; Yoon, Chun Hong; DeMirci, Hasan; ...

2016-11-04

Structural information about biological macromolecules near the atomic scale provides important insight into the functions of these molecules. To date, X-ray crystallography has been the predominant method used for macromolecular structure determination. However, challenges exist when solving structures with X-rays, including the phase problem and radiation damage. X-ray-free electron lasers (X-ray FELs) have enabled collection of diffraction information before the onset of radiation damage, yet the majority of structures solved at X-ray FELs have been phased using external information via molecular replacement. De novo phasing at X-ray FELs has proven challenging due in part to per-pulse variations in intensity andmore » wavelength. Here we report the solution of a selenobiotinyl-streptavidin structure using phases obtained by the anomalous diffraction of selenium measured at a single wavelength (Se-SAD) at the Linac Coherent Light Source. Finally, our results demonstrate Se-SAD, routinely employed at synchrotrons for novel structure determination, is now possible at X-ray FELs.« less

Current developments and tests of small x-ray optical systems for space applications

NASA Astrophysics Data System (ADS)

Pina, L.; Hudec, R.; Inneman, A.; Doubravová, D.; Marsikova, V.

2017-05-01

The paper addresses the X-ray monitoring for astrophysical applications. A novel approach based on the use of 1D and 2D "Lobster eye" optics in combination with Timepix X-ray detector in the energy range 3 - 40 keV was further studied. Wide-field optical system of this type has not been used in space yet. Designed wide-field optical system combined with Timepix X-ray detector is described together with latest experimental results obtained during laboratory tests. Proposed project includes theoretical study and a functional sample of the Timepix X-ray detector with multifoil wide-field X-ray "Lobster eye" optics. Using optics to focus X-rays on a detector is the only solution in cases where intensity of impinging X-ray radiation is below the sensitivity of the detector, e.g. while monitoring astrophysical objects in space, or phenomena in the Earth's atmosphere. The optical system is considered to be used in a student rocket experiment.

THz pulse doubler at FLASH: double pulses for pump-probe experiments at X-ray FELs.

PubMed

Zapolnova, Ekaterina; Golz, Torsten; Pan, Rui; Klose, Karsten; Schreiber, Siegfried; Stojanovic, Nikola

2018-01-01

FLASH, the X-ray free-electron laser in Hamburg, Germany, employs a narrowband high-field accelerator THz source for unique THz pump X-ray probe experiments. However, the large difference in optical paths of the THz and X-ray beamlines prevents utilization of the machine's full potential (e.g. extreme pulse energies in the soft X-ray range). To solve this issue, lasing of double electron bunches, separated by 28 periods of the driving radiofrequency (at 1.3 GHz), timed for the temporal overlap of THz and X-ray pulses at the experimental station has been employed. In order to optimize conditions for a typical THz pump X-ray probe experiment, X-ray lasing of the first bunch to one-sixth of that of the second has been suppressed. Finally, synchronization of THz radiation pulses was measured to be ∼20 fs (r.m.s.), and a solution for monitoring the arrival time for achieving higher temporal resolution is presented.

Synergistic effects of N-ethyl-N-nitrosourea (an alkylating agent with a low Swain-Scott substrate constant) and X-rays in the stamen hairs of Tradescantia clone BNL 4430.

PubMed

Shima, N; Ichikawa, S

1997-01-01

The mutagenic interaction between N-ethyl-N-nitrosourea (ENU) and X-rays was tested in the stamen hairs of Tradescantia clone BNL 4430, a blue/pink heterozygote. ENU, a monofunctional alkylating agent with a low Swain-Scott substrate constant (s) of 0.26, exhibited a strong cytotoxicity. ENU-induced somatic pink mutation frequency per 10(4) hair-cell divisions increased with increasing ENU dose, with a slope of 1.243 on a log-log graph, the slope value being similar to that for X-ray-induced mutation frequency. Three out of five combined treatments with ENU and X-rays produced mutation frequencies significantly higher than those expected from the additive effects of the two mutagens. Clear synergistic effects were detected when relatively higher X-ray doses were applied, resembling those confirmed earlier between methyl methanesulfonate (MMS) and X-rays, although the s value for ENU is very much smaller than that (0.88) for MMS. It is therefore concluded that mutagenic interactions between alkylating agents and X-rays do not have any clear relationship with the s values.

Considerations about projectile and target X-rays induced during heavy ion bombardment

NASA Astrophysics Data System (ADS)

Fernandes, F.; Bauer, D. V.; Duarte, A.; Ferrari, T. M.; Niekraszewicz, L. A. B.; Amaral, L.; Dias, J. F.

2018-02-01

In this work we present some results concerning the X-rays emitted by heavy ions during target bombardment. In this case, Cl4+ and Cl5+ ions with energies from 4 MeV to 10 MeV were employed to irradiate vitreous carbon planchets. Moreover, total X-ray production cross sections of titanium X-rays induced by chlorine ions were obtained as well for the same energy range. Only inner shell transitions were considered in the present work. The titanium target consisted of a thin film deposited over vitreous carbon planchets. The results indicate that the projectile X-ray yields increase as a function of the bombarding energy for the present energy range. Effects due to projectile charge state appears to be of minor importance at these low ion velocities. It is shown that a simple exponential function can represent the continuum background of such complex spectra. The chlorine transition rates Kβ/Kα obtained from chlorine acting as a projectile interacting with a carbon target are about half the value when compared to the chlorine Kβ/Kα ratios obtained when a LiCl target is bombarded with C+ and C3+ ions with energies from 2 MeV to 6 MeV. As far as the total X-ray production cross sections of Ti induced by chlorine ions are concerned, the ECPSSR theory underestimates the Ti total X-rays production cross sections by several orders of magnitude. The role of electron capture and possible mechanisms responsible for these effects are discussed.

Piezoelectric Ceramics of the (1 − x)Bi0.50Na0.50TiO3–xBa0.90Ca0.10TiO3 Lead-Free Solid Solution: Chemical Shift of the Morphotropic Phase Boundary, a Case Study for x = 0.06

PubMed Central

Vivar-Ocampo, Rodrigo; Pardo, Lorena; Ávila, David; Morán, Emilio; González, Amador M.; Bucio, Lauro; Villafuerte-Castrejón, María-Elena

2017-01-01

Research and development of lead-free piezoelectric materials are still the hottest topics in the field of piezoelectricity. One of the most promising lead-free family of compounds to replace lead zirconate–titanate for actuators is that of Bi0.50Na0.50TiO3 (BNT) based solid solutions. The pseudo-binary (1 − x)Bi0.50Na0.50TiO3–xBa1 − yCayTiO3 system has been proposed for high temperature capacitors and not yet fully explored as piezoelectric material. In this work, the solid solution with x = 0.06 and y = 0.10 was obtained by two different synthesis routes: solid state and Pechini, aiming at using reduced temperatures, both in synthesis (<800 °C) and sintering (<1150 °C), while maintaining appropriated piezoelectric performance. Crystal structure, ceramic grain size, and morphology depend on the synthesis route and were analyzed by X-ray diffraction, together with scanning and transmission electron microscopy. The effects of processing and ceramic microstructure on the structural, dielectric, ferroelectric, and piezoelectric properties were discussed in terms of a shift of the Morphotropic Phase Boundary, chemically induced by the synthesis route. PMID:28773096

Piezoelectric Ceramics of the (1 - x)Bi0.50Na0.50TiO₃-xBa0.90Ca0.10TiO₃ Lead-Free Solid Solution: Chemical Shift of the Morphotropic Phase Boundary, a Case Study for x = 0.06.

PubMed

Vivar-Ocampo, Rodrigo; Pardo, Lorena; Ávila, David; Morán, Emilio; González, Amador M; Bucio, Lauro; Villafuerte-Castrejón, María-Elena

2017-07-01

Research and development of lead-free piezoelectric materials are still the hottest topics in the field of piezoelectricity. One of the most promising lead-free family of compounds to replace lead zirconate-titanate for actuators is that of Bi 0.50 Na 0.50 TiO₃ (BNT) based solid solutions. The pseudo-binary (1 - x )Bi 0.50 Na 0.50 TiO₃- x Ba 1 - y Ca y TiO₃ system has been proposed for high temperature capacitors and not yet fully explored as piezoelectric material. In this work, the solid solution with x = 0.06 and y = 0.10 was obtained by two different synthesis routes: solid state and Pechini, aiming at using reduced temperatures, both in synthesis (<800 °C) and sintering (<1150 °C), while maintaining appropriated piezoelectric performance. Crystal structure, ceramic grain size, and morphology depend on the synthesis route and were analyzed by X-ray diffraction, together with scanning and transmission electron microscopy. The effects of processing and ceramic microstructure on the structural, dielectric, ferroelectric, and piezoelectric properties were discussed in terms of a shift of the Morphotropic Phase Boundary, chemically induced by the synthesis route.

Development of a Grazing Incidence X-Ray Interferometer

NASA Technical Reports Server (NTRS)

Shipley, Ann; Cash, Webster; Osterman, Steve; Joy, Marshall; Carter, James

1999-01-01

A grazing incidence x-ray interferometer design capable of micro-arcsecond level resolution is discussed. This practical design employs a Michelson Stellar interferometer approach to create x-ray interference fringes without the use of Wolter style optics or diffraction crystals. Design solutions accommodating alignment, vibration, and thermal constraints are reviewed. We present the development and demonstration of a working experiment along with tolerance studies, data analysis, and results.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yennawar, Hemant; Møller, Magda; University of Copenhagen, DK-2100 Copenhagen

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

Plasma induced grafting carboxymethyl cellulose on multiwalled carbon nanotubes for the removal of UO(2)(2+) from aqueous solution.

PubMed

Shao, Dadong; Jiang, Zhongqing; Wang, Xiangke; Li, Jiaxing; Meng, Yuedong

2009-01-29

Carboxymethyl cellulose (CMC) is grafted on multiwalled carbon nanotubes (MWCNT) by using plasma techniques. The CMC grafted MWCNT (MWCNT-g-CMC) is characterized by using Fourier transform infrared spectra (FT-IR), Raman spectra, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA)-differential thermal analysis (DTA), scanning electron microscopy (SEM), and N(2)-BET methods in detail. The application of MWCNT-g-CMC in the removal of UO(2)(2+) from aqueous solution is investigated. MWCNT-g-CMC has much higher sorption ability in the removal of UO(2)(2+) than raw MWCNT. The MWCNT-g-CMC is a suitable material in the preconcentration and solidification of heavy metal ions from large volume of aqueous solutions.

Structure, optical and phonon properties of bulk and nanocrystalline Al2-xScx(WO4)3 solid solutions doped with Cr3+

NASA Astrophysics Data System (ADS)

Mączka, M.; Hermanowicz, K.; Pietraszko, A.; Yordanova, A.; Koseva, I.

2014-01-01

Pure and Cr3+ doped nanosized Al2-xScx(WO4)3 solid solutions were prepared by co-precipitation method as well as Al2-xScx(WO4)3 single crystals were grown by high-temperature flux method. The obtained samples were characterized by X-ray, Raman, IR, absorption and luminescence methods. Single crystal X-ray diffraction showed that AlSc(WO4)3 is orthorhombic at room temperature with space group Pnca and trivalent cations are statistically distributed. Raman and IR studies showed that Al2-xScx(WO4)3 solid solutions show "two mode" behavior. They also showed that vibrational properties of nanosized samples have been weakly modified in comparison with the bulk materials. The luminescence and absorption spectra revealed that chromium ions occupy two sites of weak and strong crystal field strength.

14th International Conference on Particle Induced X-ray Emission ("PIXE 2015")

NASA Astrophysics Data System (ADS)

Przybyłowicz, Wojciech Józef; Pineda-Vargas, Carlos

2015-11-01

This special issue of Nuclear Instruments and Methods in Physics Research B contains the proceedings of the 14th International Conference on Particle Induced X-ray Emission ("PIXE 2015") that was held in Somerset West (South Africa) from 25th February to 3rd March 2015.

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

DOE PAGES

Miaja-Avila, L.; O'Neil, G. C.; Uhlig, J.; ...

2015-03-02

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, wemore » 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.« less

Stimulated Emission and Optical Properties of Solid Solutions of Cu(In,Ga)Se2 Direct Band Gap Semiconductors

NASA Astrophysics Data System (ADS)

Svitsiankou, I. E.; Pavlovskii, V. N.; Lutsenko, E. V.; Yablonskii, G. P.; Mudryi, A. V.; Borodavchenko, O. M.; Zhivulko, V. D.; Yakushev, M. V.; Martin, R.

2018-05-01

Stimulated emission, optical properties, and structural characteristics of non-irradiated and proton-irradiated Cu(In,Ga)Se2 thin films deposited on soda lime glass substrates using co-evaporation of elements in a multistage process were investigated. X-ray diffraction analysis, scanning electron microscopy, X-ray spectral analysis with energy dispersion, low-temperature photoluminescence, optical transmittance and reflectance were used to study the films. Stimulated emission at low temperatures of 20 K was found in non-irradiated and proton-irradiated Cu(In,Ga)Se2 thin films upon excitation by laser pulses of nanosecond duration with a threshold power density of 20 kW/cm2. It was shown that the appearance and parameters of the stimulated emission depend strongly on the concentration of ion-induced defects in Cu(In,Ga)Se2 thin films.

Grazing-incidence X-ray diffraction from a crystal with subsurface defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaevskii, A. Yu., E-mail: transilv@mail.ru; Golentus, I. E.

2015-03-15

The diffraction of X rays incident on a crystal surface under grazing angles under conditions of total external reflection has been investigated. An approach is proposed in which exact solutions to the dynamic problem of grazing-incidence diffraction in an ideal crystal are used as initial functions to calculate the diffuse component of diffraction in a crystal with defects. The diffuse component of diffraction is calculated for a crystal with surface defects of a dilatation-center type. Exact formulas of the continuum theory which take into account the mirror-image forces are used for defect-induced atomic displacements. Scattering intensity maps near Bragg peaksmore » are constructed for different scan modes, and the conditions for detecting primarily the diffuse component are determined. The results of dynamic calculations of grazing-incidence diffraction in defect-containing crystals are compared with calculations in the kinematic approximation.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourlier, Yoan; Cristini Robbe, Odile; Laboratoire de Physique des Lasers, Atomes et Molécules

Highlights: • CuIn{sub (1−x)}Ga{sub x}S{sub 2} thin films were prepared by sol–gel process. • Evolution of lattice parameters is characteristic of a solid solution. • Optical band gap was found to be linearly dependent on the gallium rate. - Abstract: In this paper, we report the elaboration of Cu(In,Ga)S{sub 2} chalcopyrite thin films via a sol–gel process. To reach this aim, solutions containing copper, indium and gallium complexes were prepared. These solutions were thereafter spin-coated onto the soda lime glass substrates and calcined, leading to metallic oxides thin films. Expected chalcopyrite films were finally obtained by sulfurization of oxides layersmore » using a sulfur atmosphere at 500 °C. The rate of gallium incorporation was studied both at the solutions synthesis step and at the thin films sulfurization process. Elemental and X-ray diffraction (XRD) analyses have shown the efficiency of monoethanolamine used as a complexing agent for the preparation of CuIn{sub (1−x)}Ga{sub x}S{sub 2} thin layers. Moreover, the replacement of diethanolamine by monoethanolamine has permitted the substitution of indium by isovalent gallium from x = 0 to x = 0.4 and prevented the precipitation of copper derivatives. XRD analyses of sulfurized thin films CuIn{sub (1−x)}Ga{sub x}S{sub 2,} clearly indicated that the increasing rate of gallium induced a shift of XRD peaks, revealing an evolution of the lattice parameter in the chalcopyrite structure. These results were confirmed by Raman analyses. Moreover, the optical band gap was also found to be linearly dependent upon the gallium rate incorporated within the thin films: it varies from 1.47 eV for x = 0 to 1.63 eV for x = 0.4.« less

Physical parameters for proton induced K-, L-, and M-shell ionization processes

NASA Astrophysics Data System (ADS)

Shehla; Puri, Sanjiv

2016-10-01

The proton induced atomic inner-shell ionization processes comprising radiative and non-radiative transitions are characterized by physical parameters, namely, the proton ionization cross sections, X-ray emission rates, fluorescence yields and Coster-Kronig (CK) transition probabilities. These parameters are required to calculate the K/L/M shell X-ray production (XRP) cross sections and relative X-ray intensity ratios, which in turn are required for different analytical applications. The current status of different physical parameters is presented in this report for use in various applications.

All-diamond optical assemblies for a beam-multiplexing X-ray monochromator at the Linac Coherent Light Source

PubMed Central

Stoupin, S.; Terentyev, S. A.; Blank, V. D.; Shvyd’ko, Yu. V.; Goetze, K.; Assoufid, L.; Polyakov, S. N.; Kuznetsov, M. S.; Kornilov, N. V.; Katsoudas, J.; Alonso-Mori, R.; Chollet, M.; Feng, Y.; Glownia, J. M.; Lemke, H.; Robert, A.; Sikorski, M.; Song, S.; Zhu, D.

2014-01-01

A double-crystal diamond (111) monochromator recently implemented at the Linac Coherent Light Source (LCLS) enables splitting of the primary X-ray beam into a pink (transmitted) and a monochromatic (reflected) branch. The first monochromator crystal, with a thickness of ∼100 µm, provides sufficient X-ray transmittance to enable simultaneous operation of two beamlines. This article reports the design, fabrication and X-ray characterization of the first and second (300 µm-thick) crystals utilized in the monochromator and the optical assemblies holding these crystals. Each crystal plate has a region of about 5 × 2 mm with low defect concentration, sufficient for use in X-ray optics at the LCLS. The optical assemblies holding the crystals were designed to provide mounting on a rigid substrate and to minimize mounting-induced crystal strain. The induced strain was evaluated using double-crystal X-ray topography and was found to be small over the 5 × 2 mm working regions of the crystals. PMID:25242912

Preparation of relatively clean carbon backings used in charged particle induced x-ray studies for x-rays below 4 KeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kocur, P.; Duggan, J.L.; McDaniel, F.D.

1983-04-01

In a recent series of studies of M-shell ionization induced by protons, alpha particles, and fluorine ions, an unmanageable background of low energy contaminant x rays was observed. These K-shell x rays were primarily from Ca, K, Cl, S, P, Si and Na. The energy range of these contaminants is from 3.691 to 1.041 keV. The M-shell x rays being studied were for various elements from U ( about 3.5 keV) down to Eu (1.5 keV). In order to evaluate and reduce the problem, the contaminants for carbon foils from a number of different manufacturers and a wide variety ofmore » foil float-off procedures have been studied. Carbon foils have been produced in our laboratory using carbon rods from several different manufacturers. In this paper, techniques will be described that are most appropriate to reduce the above contaminants to a reasonable level. These techniques should be useful in trace element analysis (PIXE) studies and fundamental ionization measurements for low x-ray energies.« less

Determining the Chemical Composition of Corrosion Inhibitor/Metal Interfaces with XPS: Minimizing Post Immersion Oxidation

PubMed Central

Walczak, Monika S.; Morales-Gil, Perla; Belashehr, Turia; Kousar, Kiran; Arellanes Lozada, Paulina; Lindsay, Robert

2017-01-01

An approach for acquiring more reliable X-ray photoelectron spectroscopy data from corrosion inhibitor/metal interfaces is described. More specifically, the focus is on metallic substrates immersed in acidic solutions containing organic corrosion inhibitors, as these systems can be particularly sensitive to oxidation following removal from solution. To minimize the likelihood of such degradation, samples are removed from solution within a glove box purged with inert gas, either N2 or Ar. The glove box is directly attached to the load-lock of the ultra-high vacuum X-ray photoelectron spectroscopy instrument, avoiding any exposure to the ambient laboratory atmosphere, and thus reducing the possibility of post immersion substrate oxidation. On this basis, one can be more certain that the X-ray photoelectron spectroscopy features observed are likely to be representative of the in situ submerged scenario, e.g. the oxidation state of the metal is not modified. PMID:28362363

Determining the Chemical Composition of Corrosion Inhibitor/Metal Interfaces with XPS: Minimizing Post Immersion Oxidation.

PubMed

Walczak, Monika S; Morales-Gil, Perla; Belashehr, Turia; Kousar, Kiran; Arellanes Lozada, Paulina; Lindsay, Robert

2017-03-15

An approach for acquiring more reliable X-ray photoelectron spectroscopy data from corrosion inhibitor/metal interfaces is described. More specifically, the focus is on metallic substrates immersed in acidic solutions containing organic corrosion inhibitors, as these systems can be particularly sensitive to oxidation following removal from solution. To minimize the likelihood of such degradation, samples are removed from solution within a glove box purged with inert gas, either N2 or Ar. The glove box is directly attached to the load-lock of the ultra-high vacuum X-ray photoelectron spectroscopy instrument, avoiding any exposure to the ambient laboratory atmosphere, and thus reducing the possibility of post immersion substrate oxidation. On this basis, one can be more certain that the X-ray photoelectron spectroscopy features observed are likely to be representative of the in situ submerged scenario, e.g. the oxidation state of the metal is not modified.

Solution XAS Analysis for Exploring the Active Species in Homogeneous Vanadium Complex Catalysis

NASA Astrophysics Data System (ADS)

Nomura, Kotohiro; Mitsudome, Takato; Tsutsumi, Ken; Yamazoe, Seiji

2018-06-01

Selected examples in V K-edge X-ray Absorption Near Edge Structure (XANES) analysis of a series of vanadium complexes containing imido ligands (possessing metal-nitrogen double bond) in toluene solution have been introduced, and their pre-edge and the edge were affected by their structures and nature of ligands. Selected results in exploring the oxidation states of the active species in ethylene dimerization/polymerization using homogeneous vanadium catalysts [consisting of (imido)vanadium(V) complexes and Al cocatalysts] by X-ray absorption spectroscopy (XAS) analyses have been introduced. It has been demonstrated that the method should provide more clear information concerning the active species in situ, especially by combination with the other methods (NMR and ESR spectra, X-ray crystallographic analysis, and reaction chemistry), and should be powerful tool for study of catalysis mechanism as well as for the structural analysis in solution.

X-ray fractography on fatigue fractured surface of austenitic stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yajima, Zenjiro; Tokuyama, Hideki; Kibayashi, Yasuo

1995-12-31

X-ray diffraction observation of the material internal structure beneath fracture surfaces provide fracture analysis with useful information to investigate the conditions and mechanisms of fracture. X-ray fractography is a generic name given to this technique. In the present study, X-ray fractography was applied to fatigue fracture surfaces of austenitic stainless steel (AISI 304) which consisted of solution treatment. The fatigue tests were carried out on compact tension (CT) specimens. The plastic strain on the fracture surface was estimated from measuring the line broadening of X-ray diffraction profiles. The line broadening of X-ray diffraction profiles was measured on and beneath fatiguemore » fracture surfaces. The depth of the plastic zone left on fracture surfaces was evaluated from the line broadening. The results are discussed on the basis of fracture mechanics.« less

The High Energy Astronomy Observatory X-ray Telescope

NASA Technical Reports Server (NTRS)

Miller, R.; Austin, G.; Koch, D.; Jagoda, N.; Kirchner, T.; Dias, R.

1978-01-01

The High Energy Astronomy Observatory-Mission B (HEAO-B) is a satellite observatory for the purpose of performing a detailed X-ray survey of the celestial sphere. Measurements will be made of stellar radiation in the range 0.2 through 20 keV. The primary viewing requirement is to provide final aspect solution and internal alignment information to correlate an observed X-ray image with the celestial sphere to within one-and-one-half arc seconds. The Observatory consists of the HEAO Spacecraft together with the X-ray Telescope. The Spacecraft provides the required attitude control and determination system, data telemetry system, space solar power system, and interface with the launch vehicle. The X-ray Telescope includes a high resolution mirror assembly, optical bench metering structure, X-ray detectors, detector positioning system, detector electronics and aspect sensing system.

Table-top soft x-ray microscope using laser-induced plasma from a pulsed gas jet.

PubMed

Müller, Matthias; Mey, Tobias; Niemeyer, Jürgen; Mann, Klaus

2014-09-22

An extremely compact soft x-ray microscope operating in the "water window" region at the wavelength λ = 2.88 nm is presented, making use of a long-term stable and nearly debris-free laser-induced plasma from a pulsed nitrogen gas jet target. The well characterized soft x-ray radiation is focused by an ellipsoidal grazing incidence condenser mirror. Imaging of a sample onto a CCD camera is achieved with a Fresnel zone plate using magnifications up to 500x. The spatial resolution of the recorded microscopic images is about 100 nm as demonstrated for a Siemens star test pattern.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carreras, Alejo C., E-mail: acarreras@famaf.unc.edu.ar; Cangiano, María de los A.; Ojeda, Manuel W.

The influence of the amount of complexing agent added to the starting solution on the physicochemical properties of Cu–Ni nanostructured alloys obtained through a chemical route, was studied. For this purpose, three Cu–Ni nanoalloy samples were synthesized by a previously developed procedure, starting from solutions with citric acid to metal molar ratios (C/Me) of 0.73, 1.00 and 1.50. The synthesis technique consisted in preparing a precursor via the citrate-gel method, and carrying out subsequent thermal treatments in controlled atmospheres. Sample characterization was performed by scanning electron microscopy, X-ray microanalysis, X-ray diffraction, transmission electron microscopy, X-ray nanoanalysis and electron diffraction. Inmore » the three cases, copper and nickel formed a solid solution with a Cu/Ni atomic ratio close to 50/50, and free of impurities inside the crystal structure. The citric acid content of the starting solution proved to have an important influence on the morphology, size distribution, porosity, and crystallinity of the Cu–Ni alloy microparticles obtained, but a lesser influence on their chemical composition. The molar ratio C/Me = 1.00 resulted in the alloy with the Cu/Ni atomic ratio closest to 50/50. - Highlights: • We synthesize Cu–Ni nanoalloys by a chemical route based on the citrate-gel method. • We study the influence of the complexing agent content of the starting solution. • We characterize the samples by electron microscopy and X-ray techniques. • Citric acid influences the shape, size, porosity and crystallinity of the alloys.« less

The structure of aqueous sodium hydroxide solutions: a combined solution x-ray diffraction and simulation study.

PubMed

Megyes, Tünde; Bálint, Szabolcs; Grósz, Tamás; Radnai, Tamás; Bakó, Imre; Sipos, Pál

2008-01-28

To determine the structure of aqueous sodium hydroxide solutions, results obtained from x-ray diffraction and computer simulation (molecular dynamics and Car-Parrinello) have been compared. The capabilities and limitations of the methods in describing the solution structure are discussed. For the solutions studied, diffraction methods were found to perform very well in describing the hydration spheres of the sodium ion and yield structural information on the anion's hydration structure. Classical molecular dynamics simulations were not able to correctly describe the bulk structure of these solutions. However, Car-Parrinello simulation proved to be a suitable tool in the detailed interpretation of the hydration sphere of ions and bulk structure of solutions. The results of Car-Parrinello simulations were compared with the findings of diffraction experiments.

Increased γ-H2A.X intensity in response to chronic medium-dose-rate γ-ray irradiation.

PubMed

Sugihara, Takashi; Murano, Hayato; Tanaka, Kimio

2012-01-01

The molecular mechanisms of DNA repair following chronic medium-dose-rate (MDR) γ-ray-induced damage remain largely unknown. We used a cell function imager to quantitatively measure the fluorescence intensity of γ-H2A.X foci in MDR (0.015 Gy/h and 0.06 Gy/h) or high-dose-rate (HDR) (54 Gy/h) γ-ray irradiated embryonic fibroblasts derived from DNA-dependent protein kinase mutated mice (scid/scid mouse embryonic fibroblasts (scid/scid MEFs)). The obtained results are as follows: (1) Automatic measurement of the intensity of radiation-induced γ-H2A.X foci by the cell function imager provides more accurate results compared to manual counting of γ-H2A.X foci. (2) In high-dose-rate (HDR) irradiation, γ-H2A.X foci with high fluorescence intensity were observed at 1 h after irradiation in both scid/scid and wild-type MEFs. These foci were gradually reduced through de-phosphorylation at 24 h or 72 h after irradiation. Furthermore, the fluorescence intensity at 24 h increased to a significantly greater extent in scid/scid MEFs than in wild-type MEFs in the G(1) phase, although no significant difference was observed in G(2)/M-phase MEFs, suggesting that DNA-PKcs might be associated with non-homologous-end-joining-dependent DNA repair in the G(1) phase following HDR γ-ray irradiation. (3) The intensity of γ-H2A.X foci for continuous MDR (0.06 Gy/h and 0.015 Gy/h) irradiation increased significantly and in a dose-dependent fashion. Furthermore, unlike HDR-irradiated scid/scid MEFs, the intensity of γ-H2A.X foci in MDR-irradiated scid/scid MEFs showed no significant increase in the G(1) phase at 24 h, indicating that DNA repair systems using proteins other than DNA-PKcs might induce cell functioning that are subjected to MDR γ-ray irradiation. Our results indicate that the mechanism of phosphorylation or de-phosphorylation of γ-H2A.X foci induced by chronic MDR γ-ray irradiation might be different from those induced by HDR γ-ray irradiation.

Application of relativistic electrons for the quantitative analysis of trace elements

NASA Astrophysics Data System (ADS)

Hoffmann, D. H. H.; Brendel, C.; Genz, H.; Löw, W.; Richter, A.

1984-04-01

Particle induced X-ray emission methods (PIXE) have been extended to relativistic electrons to induce X-ray emission (REIXE) for quantitative trace-element analysis. The electron beam (20 ≤ E0≤ 70 MeV) was supplied by the Darmstadt electron linear accelerator DALINAC. Systematic measurements of absolute K-, L- and M-shell ionization cross sections revealed a scaling behaviour of inner-shell ionization cross sections from which X-ray production cross sections can be deduced for any element of interest for a quantitative sample investigation. Using a multielemental mineral monazite sample from Malaysia the sensitivity of REIXE is compared to well established methods of trace-element analysis like proton- and X-ray-induced X-ray fluorescence analysis. The achievable detection limit for very heavy elements amounts to about 100 ppm for the REIXE method. As an example of an application the investigation of a sample prepared from manganese nodules — picked up from the Pacific deep sea — is discussed, which showed the expected high mineral content of Fe, Ni, Cu and Ti, although the search for aliquots of Pt did not show any measurable content within an upper limit of 250 ppm.

Direct observation of X-ray induced atomic motion using scanning tunneling microscope combined with synchrotron radiation.

PubMed

Saito, Akira; Tanaka, Takehiro; Takagi, Yasumasa; Hosokawa, Hiromasa; Notsu, Hiroshi; Ohzeki, Gozo; Tanaka, Yoshihito; Kohmura, Yoshiki; Akai-Kasaya, Megumi; Ishikawa, Tetsuya; Kuwahara, Yuji; Kikuta, Seishi; Aono, Masakazu

2011-04-01

X-ray induced atomic motion on a Ge(111)-c(2 x 8) clean surface at room temperature was directly observed with atomic resolution using a synchrotron radiation (SR)-based scanning tunneling microscope (STM) system under ultra high vacuum condition. The atomic motion was visualized as a tracking image by developing a method to merge the STM images before and after X-ray irradiation. Using the tracking image, the atomic mobility was found to be strongly affected by defects on the surface, but was not dependent on the incident X-ray energy, although it was clearly dependent on the photon density. The atomic motion can be attributed to surface diffusion, which might not be due to core-excitation accompanied with electronic transition, but a thermal effect by X-ray irradiation. The crystal surface structure was possible to break even at a lower photon density than the conventionally known barrier. These results can alert X-ray studies in the near future about sample damage during measurements, while suggesting the possibility of new applications. Also the obtained results show a new availability of the in-situ SR-STM system.

Simbol-X Mirror Module Thermal Shields: I-Design and X-Ray Transmission

NASA Astrophysics Data System (ADS)

Collura, A.; Barbera, M.; Varisco, S.; Basso, S.; Pareschi, G.; Tagliaferri, G.; Ayers, T.

2009-05-01

The Simbol-X mission is designed to fly in formation flight configuration. As a consequence, the telescope has both ends open to space, and thermal shielding at telescope entrance and exit is required to maintain temperature uniformity throughout the mirrors. Both mesh and meshless solutions are presently under study for the shields. We discuss the design and the X-ray transmission.

X-Ray Absorption Microspectroscopy with Electrostatic Force Microscopy and its Application to Chemical States Mapping

NASA Astrophysics Data System (ADS)

Ishii, M.; Rigopoulos, N.; Poolton, N. R. J.; Hamilton, B.

2007-02-01

A new technique named X-EFM that measures the x-ray absorption fine structure (XAFS) of nanometer objects was developed. In X-EFM, electrostatic force microscopy (EFM) is used as an x-ray absorption detector, and photoionization induced by x-ray absorption of surface electron trapping sites is detected by EFM. An EFM signal with respect to x-ray photon energy provides the XAFS spectra of the trapping sites. We adopted X-EFM to observe Si oxide thin films. An edge jump shift intrinsic to the X-EFM spectrum was found, and it was explained with a model where an electric field between the trapping site and probe deepens the energy level of the inner-shell. A scanning probe under x-rays with fixed photon energy provided the chemical state mapping on the surface.

Observation and theory of X-ray mirages

PubMed Central

Magnitskiy, Sergey; Nagorskiy, Nikolay; Faenov, Anatoly; Pikuz, Tatiana; Tanaka, Mamoko; Ishino, Masahiko; Nishikino, Masaharu; Fukuda, Yuji; Kando, Masaki; Kawachi, Tetsuya; Kato, Yoshiaki

2013-01-01

The advent of X-ray lasers allowed the realization of compact coherent soft X-ray sources, thus opening the way to a wide range of applications. Here we report the observation of unexpected concentric rings in the far-field beam profile at the output of a two-stage plasma-based X-ray laser, which can be considered as the first manifestation of a mirage phenomenon in X-rays. We have developed a method of solving the Maxwell–Bloch equations for this problem, and find that the experimentally observed phenomenon is due to the emergence of X-ray mirages in the plasma amplifier, appearing as phase-matched coherent virtual point sources. The obtained results bring a new insight into the physical nature of amplification of X-ray radiation in laser-induced plasma amplifiers and open additional opportunities for X-ray plasma diagnostics and extreme ultraviolet lithography. PMID:23733009

Observation and theory of X-ray mirages.

PubMed

Magnitskiy, Sergey; Nagorskiy, Nikolay; Faenov, Anatoly; Pikuz, Tatiana; Tanaka, Mamoko; Ishino, Masahiko; Nishikino, Masaharu; Fukuda, Yuji; Kando, Masaki; Kawachi, Tetsuya; Kato, Yoshiaki

2013-01-01

The advent of X-ray lasers allowed the realization of compact coherent soft X-ray sources, thus opening the way to a wide range of applications. Here we report the observation of unexpected concentric rings in the far-field beam profile at the output of a two-stage plasma-based X-ray laser, which can be considered as the first manifestation of a mirage phenomenon in X-rays. We have developed a method of solving the Maxwell-Bloch equations for this problem, and find that the experimentally observed phenomenon is due to the emergence of X-ray mirages in the plasma amplifier, appearing as phase-matched coherent virtual point sources. The obtained results bring a new insight into the physical nature of amplification of X-ray radiation in laser-induced plasma amplifiers and open additional opportunities for X-ray plasma diagnostics and extreme ultraviolet lithography.

Effect of intrinsic electronic defect states on the morphology and optoelectronic properties of Sn-rich SnS particles

NASA Astrophysics Data System (ADS)

Singh, Chetan C.; Panda, Emila

2018-05-01

A small variation in the elemental composition of a chemical compound can cause the formation of additional electronic defect states in the material, thereby altering the overall microstructure and thus induced properties. In this work, we observed chemical constitution-induced modification in the morphology and optoelectronic properties of SnS. To this end, SnS particles were prepared using the solution chemical route and were characterized using a wide range of experimental techniques, such as x-ray diffractometry, field emission scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), UV-Vis spectrophotometry, and scanning tunneling spectroscopy (STS). All these SnS particles are found to be Sn-rich and p-type. However, distinctly different morphologies (i.e., flower-like and aggregated ones) are observed. These are then correlated with the electronic defect states, which are induced because of the presence of Sn vacancies, Sn antisites, and/or Sn interstitials. A combination of EDS, XPS, and STS data confirmed the presence of a higher concentration of Sn vacancies along with lower quantities of Sn interstitials and/or antisites in the SnS particles with flower-like morphologies giving rise to higher hole concentration, which subsequently leads to reduced transport, optical band gaps, and barrier heights.

Investigating the Effect of Impurities on Macromolecule Crystal Growth in Microgravity

NASA Technical Reports Server (NTRS)

Snell, Edward H.; Judge, Russell A.; Crawford, Lisa; Forsythe, Elizabeth L.; Pusey, Marc L.; Sportiello, Michael; Todd, Paul; Bellamy, Henry; Lovelace, Jeff; Cassanto, John M.;

Action of caffeine on x-irradiated HeLa cells. VII. Evidence that caffeine enhances expression of potentially lethal radiation damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beetham, K.L.; Tolmach, L.J.

1984-12-01

HeLa cells irradiated with 2 Gy of 220-kV X rays suffer a 60-70% loss of colony-forming ability which is increased to 90% by postirradiation treatment with 10 mM caffeine for 6 hr. The detailed postirradiation patterns of cell death and sister-cell fusion in such cultures and in cultures in which the colony-forming ability was brought to about the same level by treatment with a larger (4 Gy) X-ray dose alone or by longer (48 hr) treatment with 10 mM caffeine alone were recorded by time-lapse cinemicrography. Because the patterns of cell death and fusion differ radically in irradiated and inmore » caffeine-treated cultures, the response of the additional cells killed by the combined treatment can be identified as X-ray induced rather than caffeine induced. The appearance of cultures after several days of incubation confirms the similarity of the post-treatment patterns of proliferation in cultures suffering enhanced killing to those occurring in cultures treated with larger doses of X rays alone. It is concluded that x rays do not sensitize cells to caffeine, but rather that caffeine enhanced the expression of potentially lethal radiation-induced damage.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutton, Kristin A.; Black, Paul J.; Mercer, Kermit R.

2013-12-01

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

Radiation Genetics in Wheat, V. Influence of Irradiation Time and Temperature on the Genetic Effects of Ionizing Radiation in Diploid Wheat

DOE Office of Scientific and Technical Information (OSTI.GOV)

MATSUMURA, Seiji

1960-01-01

Dcrmant seeds of Triticum monococcum flavescens were exposed to x and gamma rays at the dosage of 10 and 20 kr. Growth of seedlings, single spike fertility, and chromosome aberrations of X/sub 1/ plant and gene mutations in X/ sub 2/ were compared for acute and chronic irradiation. At acute irradiation with x and gamma rays, treatment was given either immediately before sowing or the irradiated seeds were kept for 30 days in storage at room temperature (abcut 20 deg C) or at 5 deg C. Also, the effect of beta radiation by P/sup 32/ was examined for comparison. Themore » relation between the inhibition of seedling growth and dosage, temperature in storage and irradiation time coincides roughly with the relation between the percentage of induced sterility and all those condions. X and gamma irradiations were far more effective at 20 kr than at 10 kr. In the case of 30 day storage, gamma rays inhibited the growth of seedlings and reduced the fertility stronger than x rays, whereas irradiation applied just before sowing showed the reverse relation. It was further observed, especially with gamma rays, that low temperature had the strongest inhibitory effect. At 10 kr, acute gamma irradiation was more effective than the chronic one, whereas at 20 kr the reverse relation was observed. The frequency of chromosome aberrations and gene mutations was strikingly higher at 2O kr than at 10 kr. Irradiation just before sowing and 30 day storage at low tempera ture were more effective than storage at room temperature after irradiation. The effect of gamma irradiation was less. The effects of beta irradiation were unexpectedly slight. It was found from another experiment with seed absorption of p/sup 32/ solution that the actual dosage of beta rays was very low.« less

Laser-induced Multi-energy Processing in Diamond Growth

DTIC Science & Technology

2012-05-01

microscopy (SEM) and energy dispersive X - ray (EDX) measurements, Drs. Yi Liu and Shah Valloppilly from Nebraska Center for Materials and Nanoscience...NCMN) at UNL for help on X - Ray diffraction (XRD) measurements, and Professor Steve W. Martin and Dr. Young Sik Kim from the Department of Material...spectroscopy and X - ray diffraction ................... 62 4.4 Conclusions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loether, A.; Adams, B. W.; DiCharia, A.

A hard x-ray pump–probe spectrometer using a multi-crystal Bragg reflector is demonstrated at a third generation synchrotron source. This device derives both broadband pump and monochromatic probe pulses directly from a single intense, broadband x-ray pulse centered at 8.767 keV. In conclusion, we present a proof-of-concept experiment which directly measures x-ray induced crystalline lattice strain.

Dopant concentration dependent optical and X-Ray induced photoluminescence in Eu3+ doped La2Zr2O7

NASA Astrophysics Data System (ADS)

Pokhrel, Madhab; Brik, Mikhail; Mao, Yuanbing

2015-03-01

Herein, we will be presenting the dopant (Eu) concentration dependent high density La2Zr2O7 nanoparticles for optical and X-ray scintillation applications by use of X - ray diffraction, Raman, FTIR, scanning electron microscope (SEM), transmission electron microscopy (TEM), optically and X-ray excited photoluminescence (PL). Several theoretical methods have been used in order to investigate the structural, electronic, optical, elastic, dynamic properties of Eu doped La2Zr2O7. It is observed that Eu: La2Zr2O7 shows an intense red luminescence under 258, 322, 394 and 465 nm excitation. The optical intensity of Eu: La2Zr2O7 depends on the dopant concentration of Eu3+. Following high energy excitation with X-rays, Eu: La2Zr2O7 shows an atypical Eu PL response (scintillation) with a red emission. The intense color emission of Eu obtained under 258 nm excitation, the X-ray induced luminescence property along with reportedly high density of La2Zr2O7, makes these nanomaterials attractive for optical and X-ray applications. The authors thank the support from the Defense Threat Reduction Agency (DTRA) of the U.S. Department of Defense (Award #HDTRA1-10-1-0114).

X-ray off-specular reflectivity studies of electrochemical pitting of Cu surfaces in sodium bicarbonate solution

NASA Astrophysics Data System (ADS)

Feng, Y. P.; Sinha, S. K.; Melendres, C. A.; Lee, D. D.

1996-02-01

We have studied the electrochemically-induced pitting process on a Cu electrode in NaHCO 3 solution using in-situ X-ray off-specular reflectivity measurements. The morphology and growth dynamics of the localized corrosion sites or pits were studied as the applied potential was varied from the cathodic region where the Cu surface is relatively free of oxide films to the anodic region where surface roughening occurs by general corrosion with concomitant formation of an oxide film. Quantitative analysis of the experimental results indicates that early pitting proceeds in favor of nucleation of pit clusters over individual pit growth. It was found that the lateral distribution of the pits is not random but exhibits a short-range order as evidenced by the appearance of a side peak in the transverse off-specular reflectivity. The position, height, and width of the peak was modeled to yield the average size, nearest-neighbor distance (within any one of the clusters), and over-all density of the pits averaged over the entire illuminated surface. In addition, measurements of the longitudinal off-specular reflectivity indicate a bimodal depth distribution for the pits, suggesting a “film breaking” type of pitting mechanism.

Photocatalytic degradation of Orange G on nitrogen-doped TiO2 catalysts under visible light and sunlight irradiation.

PubMed

Sun, Jianhui; Qiao, Liping; Sun, Shengpeng; Wang, Guoliang

2008-06-30

In this paper, the degradation of an azo dye Orange G (OG) on nitrogen-doped TiO2 photocatalysts has been investigated under visible light and sunlight irradiation. Under visible light irradiation, the doped TiO2 nanocatalysts demonstrated higher activity than the commercial Dugussa P25 TiO2, allowing more efficient utilization of solar light, while under sunlight, P25 showed higher photocatalytic activity. According to the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectra analyses, it was found that both the nanosized anatase structure and the appearance of new absorption band in the visible region caused by nitrogen doping were responsible for the significant enhancement of OG degradation under visible light. In addition, the photosensitized oxidation mechanism originated from OG itself was also considered contributing to the higher visible-light-induced degradation efficiency. The effect of the initial pH of the solution and the dosage of hydrogen peroxide under different light sources was also investigated. Under visible light and sunlight, the optimal solution pH was both 2.0, while the optimal dosage of H2O2 was 5.0 and 15.0 mmol/l, respectively.

Anisotropic pyrochemical microetching of poly(tetrafluoroethylene) initiated by synchrotron radiation-induced scission of molecule bonds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamaguchi, Akinobu, E-mail: yamaguti@lasti.u-hyogo.ac.jp, E-mail: utsumi@lasti.u-hyogo.ac.jp; Kido, Hideki; Utsumi, Yuichi, E-mail: yamaguti@lasti.u-hyogo.ac.jp, E-mail: utsumi@lasti.u-hyogo.ac.jp

2016-02-01

We developed a process for micromachining polytetrafluoroethylene (PTFE): anisotropic pyrochemical microetching induced by synchrotron X-ray irradiation. X-ray irradiation was performed at room temperature. Upon heating, the irradiated PTFE substrates exhibited high-precision features. Both the X-ray diffraction peak and Raman signal from the irradiated areas of the substrate decreased with increasing irradiation dose. The etching mechanism is speculated as follows: X-ray irradiation caused chain scission, which decreased the number-average degree of polymerization. The melting temperature of irradiated PTFE decreased as the polymer chain length decreased, enabling the treated regions to melt at a lower temperature. The anisotropic pyrochemical etching process enabledmore » the fabrication of PTFE microstructures with higher precision than simultaneously heating and irradiating the sample.« less

Investigation of L X-ray intensity ratios in Pt induced by proton collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaur, Manpuneet; Kaur, Mandeep; Department of Physics, Punjabi University, Patiala, 147 002, Punjab

2015-08-28

A survey of literature on L X-ray parameters inspires us for taking up the present investigation. These parameters are useful to study atomic properties. In view of this, we report L X-ray intensity ratios for Pt, namely, L{sub ℓ} / L{sub α}, L{sub β} / L{sub α} and L{sub γ} / L{sub α} with proton collisions over the energy range 260 - 400 keV with an interval of 20 keV. The intention of research presented in this paper is to explore their energy dependence and comparison with theoretical calculations. These analyses will yield a data in the low energy regionmore » which assist in better clarity of proton induced X-ray emission phenomenon.« less

Molecular structure in the solid state by X-ray crystallography and SSNMR and in solution by NMR of two 1,4-diazepines

NASA Astrophysics Data System (ADS)

Nieto, Carla I.; Sanz, Dionisia; Claramunt, Rosa M.; Torralba, M. Carmen; Torres, M. Rosario; Alkorta, Ibon; Elguero, José

2018-03-01

The crystals of two 1,4-diazepines prepared from curcuminoid β-diketones and ethylenediamine were studied by X-ray crystallography and NMR. Their tautomerism, intramolecular hydrogen bonds and conformation were determined.

Comparative study of X-ray emission from plasma focus relative to different preionization schemes

NASA Astrophysics Data System (ADS)

Ahmad, S.; Qayyum, A.; Hassan, M.; Zakaullah, M.

2017-07-01

A 2.7-kJ Mather-type plasma focus has been investigated for X-ray emission with preionization produced by an α-source, a β-source, and a shunt resistor. Time-resolved and time integrated measurements are carried out using a PIN-diode-based X-ray spectrometer and pinhole camera. The β-source (28Ni63) assisted preionization enhances the X-ray emission up to 25%, while preionization induced by depleted uranium (92U238) increases both Cu-Kα and total X-ray yield of about 100%. The preionization caused by the optimum shunt resistor enhances the Cu-Kα and total X-ray yield of about 53%. It is found that preionization also broadens the working pressure range for the high X-ray yield and improves the shot-to-shot reproducibility of the system. Pinhole images reveal that the X-ray emission from the anode tip is dominant owing to impact of electron bombardment, while the X-ray emission from hot spots is also visible.

Local terahertz field enhancement for time-resolved x-ray diffraction

DOE PAGES

Kozina, M.; Pancaldi, M.; Bernhard, C.; ...

2017-02-20

We report local field strength enhancement of single-cycle terahertz (THz) pulses in an ultrafast time-resolved x-ray diffraction experiment. We show that patterning the sample with gold microstructures increases the THz field without changing the THz pulse shape or drastically affecting the quality of the x-ray diffraction pattern. Lastly, we find a five-fold increase in THz-induced x-ray diffraction intensity change in the presence of microstructures on a SrTiO 3 thin-film sample.

Elucidating the Wavelength Dependence of Phonon Scattering in Nanoparticle-Matrix Composites using Phonon Spectroscopy

DTIC Science & Technology

2016-07-11

composites with x - ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Rutherford backscattering spectroscopy...RBS), particle-induced x - ray emission (PIXE), and energy dispersive x - ray spectroscopy (EDX). This work complements earlier works on CdSe...sample shows only In2Se3 and CdIn2Se4 XRD peaks (Figure 1.4e), it is stoichiometrically   Figure 1.4. X - ray diffraction patterns of (a) γ-In2Se3

Local terahertz field enhancement for time-resolved x-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozina, M.; Pancaldi, M.; Bernhard, C.

We report local field strength enhancement of single-cycle terahertz (THz) pulses in an ultrafast time-resolved x-ray diffraction experiment. We show that patterning the sample with gold microstructures increases the THz field without changing the THz pulse shape or drastically affecting the quality of the x-ray diffraction pattern. Lastly, we find a five-fold increase in THz-induced x-ray diffraction intensity change in the presence of microstructures on a SrTiO 3 thin-film sample.

X-Ray Scattering Echoes and Ghost Halos from the Intergalactic Medium: Relation to the Nature of AGN Variability

NASA Astrophysics Data System (ADS)

Corrales, Lia

2015-05-01

X-ray bright quasars might be used to trace dust in the circumgalactic and intergalactic medium through the phenomenon of X-ray scattering, which is observed around Galactic objects whose light passes through a sufficient column of interstellar gas and dust. Of particular interest is the abundance of gray dust larger than 0.1 μ m, which is difficult to detect at other wavelengths. To calculate X-ray scattering from large grains, one must abandon the traditional Rayleigh-Gans approximation. The Mie solution for the X-ray scattering optical depth of the universe is ∼ 1%. This presents a great difficulty for distinguishing dust scattered photons from the point source image of Chandra, which is currently unsurpassed in imaging resolution. The variable nature of AGNs offers a solution to this problem, as scattered light takes a longer path and thus experiences a time delay with respect to non-scattered light. If an AGN dims significantly (≳ 3 dex) due to a major feedback event, the Chandra point source image will be suppressed relative to the scattering halo, and an X-ray echo or ghost halo may become visible. I estimate the total number of scattering echoes visible by Chandra over the entire sky: {{N}ech}∼ {{10}3}({{ν }fb}/y{{r}-1}), where {{ν }fb} is the characteristic frequency of feedback events capable of dimming an AGN quickly.

Angular distribution and polarization of X-ray radiation in highly charged He-like ions: hyperfine-induced transition

NASA Astrophysics Data System (ADS)

Chen, Zhan-Bin; Dong, Chen-Zhong

2018-06-01

The angular distribution and polarization properties of the X-rays produced by the hyperfine-induced transition are investigated within a fully relativistic distorted-wave approximation. The calculations are performed for the 1 s2 p 3/2 3P2 F i = 3/2 → 1 s 2 1S0 F f = 1/2 component of the Kα 1 decay for highly charged He-like 119Sn48+ and 207Tl79+ ions with nuclear spin I = 1/2 following impact excitations by an un-polarized and a completely longitudinally-polarized electron beam, respectively. The Breit interaction and mutipole mixing between the leading M2 decay and the hyperfine-induced E1 decay corrections to both linear and circular polarizations of the emitted X-ray radiations are evaluated. All these effects are found to be significant and may potentially explain the disagreement between the theories and experiments related to the polarization properties of the X-ray radiation.

Proton-induces and x-ray induced fluorescence analysis of scoliotic tissue

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panessa-Warren, B J; Kraner, H W; Jones, K W

1980-02-01

Adolescent idiopathic scoliosis is characterized by a curvature or assymetry of the spine which may become progressively more severe, with clinical symptoms appearing just prior to, or during, puberty. The incidence for scoliosis in the age group from 12 to 14 years of age has been reported as high as 8 to 10%, with more than 80% of the cases occurring in females. Although pathologic changes exist in muscles from both sides of the spinal curvature, and no statistically significant side differences have been reported, morphologic changes suggest that the concanve side is the most affected. This paper reports ourmore » preliminary data on the elemental composition of individual muscle fibers derived from convex, concave and gluteal scoliotic muscle, and erythrocytes from scoliotic and normal patients, analyzed by proton induced x-ray emission (PIXE) and x-ray fluorescence spectroscopy (XRF). A new type of specimen holder was designed for this study which offers low x-ray background, minimal absorption and maintenance of a moist environment around the specimen.« less

Separation of detector non-linearity issues and multiple ionization satellites in alpha-particle PIXE

NASA Astrophysics Data System (ADS)

Campbell, John L.; Ganly, Brianna; Heirwegh, Christopher M.; Maxwell, John A.

2018-01-01

Multiple ionization satellites are prominent features in X-ray spectra induced by MeV energy alpha particles. It follows that the accuracy of PIXE analysis using alpha particles can be improved if these features are explicitly incorporated in the peak model description when fitting the spectra with GUPIX or other codes for least-squares fitting PIXE spectra and extracting element concentrations. A method for this incorporation is described and is tested using spectra recorded on Mars by the Curiosity rover's alpha particle X-ray spectrometer. These spectra are induced by both PIXE and X-ray fluorescence, resulting in a spectral energy range from ∼1 to ∼25 keV. This range is valuable in determining the energy-channel calibration, which departs from linearity at low X-ray energies. It makes it possible to separate the effects of the satellites from an instrumental non-linearity component. The quality of least-squares spectrum fits is significantly improved, raising the level of confidence in analytical results from alpha-induced PIXE.

X-ray lasers for structural and dynamic biology

NASA Astrophysics Data System (ADS)

Spence, J. C. H.; Weierstall, U.; Chapman, H. N.

2012-10-01

Research opportunities and techniques are reviewed for the application of hard x-ray pulsed free-electron lasers (XFEL) to structural biology. These include the imaging of protein nanocrystals, single particles such as viruses, pump-probe experiments for time-resolved nanocrystallography, and snapshot wide-angle x-ray scattering (WAXS) from molecules in solution. The use of femtosecond exposure times, rather than freezing of samples, as a means of minimizing radiation damage is shown to open up new opportunities for the molecular imaging of biochemical reactions at room temperature in solution. This is possible using a ‘diffract-and-destroy’ mode in which the incident pulse terminates before radiation damage begins. Methods for delivering hundreds of hydrated bioparticles per second (in random orientations) to a pulsed x-ray beam are described. New data analysis approaches are outlined for the correlated fluctuations in fast WAXS, for protein nanocrystals just a few molecules on a side, and for the continuous x-ray scattering from a single virus. Methods for determining the orientation of a molecule from its diffraction pattern are reviewed. Methods for the preparation of protein nanocrystals are also reviewed. New opportunities for solving the phase problem for XFEL data are outlined. A summary of the latest results is given, which now extend to atomic resolution for nanocrystals. Possibilities for time-resolved chemistry using fast WAXS (solution scattering) from mixtures is reviewed, toward the general goal of making molecular movies of biochemical processes.

Non-destructive elemental analysis of a carbonaceous chondrite with direct current Muon beam at MuSIC.

PubMed

Terada, K; Sato, A; Ninomiya, K; Kawashima, Y; Shimomura, K; Yoshida, G; Kawai, Y; Osawa, T; Tachibana, S

2017-11-13

Electron- or X-ray-induced characteristic X-ray analysis has been widely used to determine chemical compositions of materials in vast research fields. In recent years, analysis of characteristic X-rays from muonic atoms, in which a muon is captured, has attracted attention because both a muon beam and a muon-induced characteristic X-ray have high transmission abilities. Here we report the first non-destructive elemental analysis of a carbonaceous chondrite using one of the world-leading intense direct current muon beam source (MuSIC; MUon Science Innovative Channel). We successfully detected characteristic muonic X-rays of Mg, Si, Fe, O, S and C from Jbilet Winselwan CM chondrite, of which carbon content is about 2 wt%, and the obtained elemental abundance pattern was consistent with that of CM chondrites. Because of its high sensitivity to carbon, non-destructive elemental analysis with a muon beam can be a novel powerful tool to characterize future retuned samples from carbonaceous asteroids.

X-ray pushing of a mechanical microswing.

PubMed

Siria, A; Rodrigues, M S; Dhez, O; Schwartz, W; Torricelli, G; Ledenmat, S; Rochat, N; Auvert, G; Bikondoa, O; Metzger, T H; Wermeille, D; Felici, R; Comin, F; Chevrier, J

2008-11-05

We report here for the first time the combination of x-ray synchrotron light and a micro-electro-mechanical system (MEMS). We show how it is possible to modulate in real time a MEMS mass distribution to induce a nanometric and tunable mechanical oscillation. The quantitative experimental demonstration we present here uses periodic thermal dilatation of a Ge microcrystal attached to a Si microlever, induced by controlled absorption of an intensity modulated x-ray microbeam. The mechanism proposed can be envisaged either for the detection of small heat flux or for the actuation of a mechanical system.

Strain-induced nanostructure of Pb(Mg1/3Nb2/3)O3-PbTiO3 on SrTiO3 epitaxial thin films with low PbTiO3 concentration

NASA Astrophysics Data System (ADS)

Kiguchi, Takanori; Fan, Cangyu; Shiraishi, Takahisa; Konno, Toyohiko J.

2017-10-01

The singularity of the structure in (1 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) (x = 0-50 mol %) epitaxial thin films of 100 nm thickness was investigated from the viewpoint of the localized residual strain in the nanoscale. The films were deposited on SrTiO3 (STO) (001) single-crystal substrates by chemical solution deposition (CSD) using metallo-organic decomposition (MOD) solutions. X-ray and electron diffraction patterns revealed that PMN-xPT thin films included a single phase of the perovskite-type structure with the cube-on-cube orientation relationship between PMN-xPT and STO: (001)Film ∥ (001)Sub, [100]Film ∥ [100]Sub. X-ray reciprocal space maps showed an in-plane tensile strain in all the compositional ranges considered. Unit cells in the films were strained from the rhombohedral (pseudocubic) (R) phase to a lower symmetry crystal system, the monoclinic (MB) phase. The morphotropic phase boundary (MPB) that split the R and tetragonal (T) phases was observed at x = 30-35 for bulk crystals of PMN-xPT, whereas the strain suppressed the transformation from the R phase to the T phase in the films up to x = 50. High-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) analysis and its related local strain analysis revealed that all of the films have a bilayer morphology. The nanoscale strained layer formed only above the film/substrate semi-coherent interface. The misfit dislocations generated the localized and periodic strain fields deformed the unit cells between the dislocation cores from the R to an another type of the monoclinic (MA) phase. Thus, the singular and localized residual strains in the PMN-xPT/STO (001) epitaxial thin films affect the phase stability around the MPB composition and result in the MPB shift phenomena.

Cu{sub 2}Mn{sub 1-x}Co{sub x}SnS{sub 4}: Novel keesterite type solid solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopez-Vergara, F., E-mail: fer_martina@u.uchile.cl; Galdamez, A., E-mail: agaldamez@uchile.cl; Manriquez, V.

2013-02-15

A new family of Cu{sub 2}Mn{sub 1-x}Co{sub x}SnS{sub 4} chalcogenides has been synthesized by conventional solid-state reactions at 850 Degree-Sign C. The reactions products were characterized by powder X-ray diffraction (XRD), energy-dispersive X-ray analysis (SEM-EDS), Raman spectroscopy and magnetic susceptibility. The crystal structures of two members of the solid solution series Cu{sub 2}Mn{sub 0.4}Co{sub 0.6}SnS{sub 4} and Cu{sub 2}Mn{sub 0.2}Co{sub 0.8}SnS{sub 4} have been determined by single-crystal X-ray diffraction. Both phases crystallize in the tetragonal keesterite-type structure (space group I4{sup Macron }). The distortions of the tetrahedral volume of Cu{sub 2}Mn{sub 0.4}Co{sub 0.6}SnS{sub 4} and Cu{sub 2}Mn{sub 0.2}Co{sub 0.8}SnS{sub 4}more » were calculated and compared with the corresponding differences in the Cu{sub 2}MnSnS{sub 4} (stannite-type) end-member. The compounds show nearly the same Raman spectral features. Temperature-dependent magnetization measurements (ZFC/FC) and high-temperature susceptibility indicate that these solid solutions are antiferromagnetic. - Graphical abstract: View along [100] of the Cu{sub 2}Mn{sub 1-x}Co{sub x}SnS{sub 4} structure showing tetrahedral units and magnetic measurement ZFC-FC at 500 Oe. The insert shows the 1/{chi}-versus-temperature plot fitted by a Curie-Weiss law. Highlights: Black-Right-Pointing-Pointer Cu{sub 2}Mn{sub 1-x}Co{sub x}SnS{sub 4} solid solutions belong to the family of compounds adamantine. Black-Right-Pointing-Pointer Resolved single crystals of the solid solutions have space group I4{sup Macron }. Black-Right-Pointing-Pointer The distortion of the tetrahedral volume of Cu{sub 2}Mn{sub 1-x}Co{sub x}SnS{sub 4} were calculated. Black-Right-Pointing-Pointer These solid solutions are antiferromagnetic.« less

Transmission type flat-panel X-ray source using ZnO nanowire field emitters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Daokun; Song, Xiaomeng; Zhang, Zhipeng

2015-12-14

A transmission type flat-panel X-ray source in diode structure was fabricated. Large-scale patterned ZnO nanowires grown on a glass substrate by thermal oxidation were utilized as field emitters, and tungsten thin film coated on silica glass was used as the transmission anode. Uniform distribution of X-ray generation was achieved, which benefited from the uniform electron emission from ZnO nanowires. Self-ballasting effect induced by the intrinsic resistance of ZnO nanowire and decreasing of screening effect caused by patterned emitters account for the uniform emission. Characteristic X-ray peaks of W-L lines and bremsstrahlung X-rays have been observed under anode voltages at amore » range of 18–20 kV, the latter of which were the dominant X-ray signals. High-resolution X-ray images with spatial resolution less than 25 μm were obtained by the flat-panel X-ray source. The high resolution was attributed to the small divergence angle of the emitted X-rays from the transmission X-ray source.« less

Electronic structure of the organic semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from soft x-ray spectroscopies and density functional theory calculations.

PubMed

DeMasi, A; Piper, L F J; Zhang, Y; Reid, I; Wang, S; Smith, K E; Downes, J E; Peltekis, N; McGuinness, C; Matsuura, A

2008-12-14

The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq(3)) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq(3), and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studies and the present data reveal the presence of clear photon-induced damage in the former.

Light-Induced Surface Reactions at the Bismuth Vanadate/Potassium Phosphate Interface.

PubMed

Favaro, Marco; Abdi, Fatwa F; Lamers, Marlene; Crumlin, Ethan J; Liu, Zhi; van de Krol, Roel; Starr, David E

2018-01-18

Bismuth vanadate has recently drawn significant research attention as a light-absorbing photoanode due to its performance for photoelectrochemical water splitting. In this study, we use in situ ambient pressure X-ray photoelectron spectroscopy with "tender" X-rays (4.0 keV) to investigate a polycrystalline bismuth vanadate (BiVO 4 ) electrode in contact with an aqueous potassium phosphate (KPi) solution at open circuit potential under both dark and light conditions. This is facilitated by the creation of a 25 to 30 nm thick electrolyte layer using the "dip-and-pull" method. We observe that under illumination bismuth phosphate forms on the BiVO 4 surface leading to an increase of the surface negative charge. The bismuth phosphate layer may act to passivate surface states observed in photoelectrochemical measurements. The repulsive interaction between the negatively charged surface under illumination and the phosphate ions in solution causes a shift in the distribution of ions in the thin aqueous electrolyte film, which is observed as an increase in their photoelectron signals. Interestingly, we find that such changes at the BiVO 4 /KPi electrolyte interface are reversible upon returning to dark conditions. By measuring the oxygen 1s photoelectron peak intensities from the phosphate ions and liquid water as a function of time under dark and light conditions, we determine the time scales for the forward and reverse reactions. Our results provide direct evidence for light-induced chemical modification of the BiVO 4 /KPi electrolyte interface.

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

NASA Technical Reports Server (NTRS)

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 pulsars and supergiant fast X ray transients.

SOLEIL shining on the solution-state structure of biomacromolecules by synchrotron X-ray footprinting at the Metrology beamline.

PubMed

Baud, A; Aymé, L; Gonnet, F; Salard, I; Gohon, Y; Jolivet, P; Brodolin, K; Da Silva, P; Giuliani, A; Sclavi, B; Chardot, T; Mercère, P; Roblin, P; Daniel, R

2017-05-01

Synchrotron X-ray footprinting complements the techniques commonly used to define the structure of molecules such as crystallography, small-angle X-ray scattering and nuclear magnetic resonance. It is remarkably useful in probing the structure and interactions of proteins with lipids, nucleic acids or with other proteins in solution, often better reflecting the in vivo state dynamics. To date, most X-ray footprinting studies have been carried out at the National Synchrotron Light Source, USA, and at the European Synchrotron Radiation Facility in Grenoble, France. This work presents X-ray footprinting of biomolecules performed for the first time at the X-ray Metrology beamline at the SOLEIL synchrotron radiation source. The installation at this beamline of a stopped-flow apparatus for sample delivery, an irradiation capillary and an automatic sample collector enabled the X-ray footprinting study of the structure of the soluble protein factor H (FH) from the human complement system as well as of the lipid-associated hydrophobic protein S3 oleosin from plant seed. Mass spectrometry analysis showed that the structural integrity of both proteins was not affected by the short exposition to the oxygen radicals produced during the irradiation. Irradiated molecules were subsequently analysed using high-resolution mass spectrometry to identify and locate oxidized amino acids. Moreover, the analyses of FH in its free state and in complex with complement C3b protein have allowed us to create a map of reactive solvent-exposed residues on the surface of FH and to observe the changes in oxidation of FH residues upon C3b binding. Studies of the solvent accessibility of the S3 oleosin show that X-ray footprinting offers also a unique approach to studying the structure of proteins embedded within membranes or lipid bodies. All the biomolecular applications reported herein demonstrate that the Metrology beamline at SOLEIL can be successfully used for synchrotron X-ray footprinting of biomolecules.

Recent results of synchrotron radiation induced total reflection X-ray fluorescence analysis at HASYLAB, beamline L

NASA Astrophysics Data System (ADS)

Streli, C.; Pepponi, G.; Wobrauschek, P.; Jokubonis, C.; Falkenberg, G.; Záray, G.; Broekaert, J.; Fittschen, U.; Peschel, B.

2006-11-01

At the Hamburger Synchrotronstrahlungslabor (HASYLAB), Beamline L, a vacuum chamber for synchrotron radiation-induced total reflection X-ray fluorescence analysis, is now available which can easily be installed using the adjustment components for microanalysis present at this beamline. The detector is now in the final version of a Vortex silicon drift detector with 50-mm 2 active area from Radiant Detector Technologies. With the Ni/C multilayer monochromator set to 17 keV extrapolated detection limits of 8 fg were obtained using the 50-mm 2 silicon drift detector with 1000 s live time on a sample containing 100 pg of Ni. Various applications are presented, especially of samples which are available in very small amounts: As synchrotron radiation-induced total reflection X-ray fluorescence analysis is much more sensitive than tube-excited total reflection X-ray fluorescence analysis, the sampling time of aerosol samples can be diminished, resulting in a more precise time resolution of atmospheric events. Aerosols, directly sampled on Si reflectors in an impactor were investigated. A further application was the determination of contamination elements in a slurry of high-purity Al 2O 3. No digestion is required; the sample is pipetted and dried before analysis. A comparison with laboratory total reflection X-ray fluorescence analysis showed the higher sensitivity of synchrotron radiation-induced total reflection X-ray fluorescence analysis, more contamination elements could be detected. Using the Si-111 crystal monochromator also available at beamline L, XANES measurements to determine the chemical state were performed. This is only possible with lower sensitivity as the flux transmitted by the crystal monochromator is about a factor of 100 lower than that transmitted by the multilayer monochromator. Preliminary results of X-ray absorption near-edge structure measurements for As in xylem sap from cucumber plants fed with As(III) and As(V) are reported. Detection limits of 170 ng/l of As in xylem sap were achieved.

Curved focusing crystals for hard X-ray astronomy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferrari, C., E-mail: ferrari@imem.cnr.it; Buffagni, E.; Bonnini, E.

A lens made by a properly arranged array of crystals can be used to focus x-rays of energy ranging from 30 to 500 keV for x-ray astronomy. Mosaic or curved crystals can be employed as x-ray optical elements. In this work self standing curved focusing Si and GaAs crystals in which the lattice bending is induced by a controlled damaging process on one side of planar crystals are characterized. Diffraction profiles in Laue geometry have been measured in crystals at x-ray energies E = 17, 59 and 120 keV. An enhancement of diffraction efficiency is found in asymmetric geometries.

Effective adsorption and collection of cesium from aqueous solution using graphene oxide grown on porous alumina

NASA Astrophysics Data System (ADS)

Entani, Shiro; Honda, Mitsunori; Shimoyama, Iwao; Li, Songtian; Naramoto, Hiroshi; Yaita, Tsuyoshi; Sakai, Seiji

2018-04-01

Graphene oxide (GO) with a large surface area was synthesized by the direct growth of GO on porous alumina using chemical vapor deposition to study the Cs adsorption mechanism in aqueous solutions. Electronic structure analysis employing in situ near-edge X-ray absorption fine structure spectroscopy and X-ray photoelectron spectroscopy measurements clarifies the Cs atoms bond via oxygen functional groups on GO in the aqueous solution. The Cs adsorption capacity was found to be as high as 650-850 mg g-1, which indicates that the GO/porous alumina acts as an effective adsorbent with high adsorption efficiency for radioactive nuclides in aqueous solutions.

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

NASA Astrophysics Data System (ADS)

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

2014-06-01

Context. BD + 60° 73 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. Aims: We aim to characterise the binary system IGR J00370+6122 by deriving its orbital and physical parameters. Methods: We obtained high-resolution spectra of BD + 60° 73 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 also analysed the RXTE/ASM and Swift/BAT light curves to confirm the stability of the periodicity. Results: BD + 60° 73 is a BN0.7 Ib low-luminosity supergiant located at a distance ~3.1 kpc, in the Cas OB4 association. We derive Teff = 24 000 K and log gc = 3.0, and chemical abundances consistent with a moderately high level of evolution. The spectroscopic and evolutionary masses are consistent at the 1-σ level with a mass M∗ ≈ 15 M⊙. The recurrence time of the X-ray flares is the orbital period of the system. The neutron star is in a high-eccentricity (e = 0.56 ± 0.07) orbit, and the X-ray emission is strongly peaked around orbital phase φ = 0.2, though the observations are consistent with some level of X-ray activity happening at all orbital phases. Conclusions: The X-ray behaviour of IGR J00370+6122 is reminiscent of "intermediate" supergiant X-ray transients, though its peak luminosity is rather low. The orbit is somewhat wider than those of classical persistent supergiant X-ray binaries, which when combined with the low luminosity of the mass donor, explains the low X-ray luminosity. IGR J00370+6122 will very likely evolve towards a persistent supergiant system, highlighting the evolutionary connection between different classes of wind-accreting X-ray sources.

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.

PubMed

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 intracellular milieu is discussed.

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

PubMed Central

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 intracellular milieu is discussed. PMID:26318000

Mutagenic and lethal effects of (5-/sup 125/I)lodo-2'-deoxyuridine incorporated into DNA of mammalian cells, and their RBEs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyazaki, N.; Fujiwara, Y.

1981-12-01

Decay of /sup 125/I unifilarly incorporated as 5-iodo-2'-deoxyuridine (IdUrd) into DNA of V79 Chinese hamster cells was approximately an order of magnitude more effective in inducing both 6-thioguanine-resistant mutation and cell inactivation than external X rays under equivalent conditions. RBEs of mutation and killing induced by /sup 125/I decays, compared with 170-kVp X rays of low LET, were approx. = 11 for mutation (ratio of the induction rate in frequency/rad = 11.3 X 10/sup -7/ (/sup 125/I)/100 X 10/sup -7/ (X rays at -79/sup o/C)) and approx. = 10 for cell inactivation (D/sub 0/ ratio = 505 rad (X raysmore » at -79/sup o/C)/52 rad (/sup 125/I)). These RBE values may well exceed the reported maximum values for high-LET radiation in the LET range of 80-110 keV/..mu..m, suggesting that the Auger effect is different from the high-LET radiation effect alone. Thus these biological consequences arise not only from radiation effects of Auger electrons on the immediate vicinity in DNA, but also from the nonionogenic effect through charge transfer processes. In addition, higher inductions of mutation and killing by external X rays in unifilarly IdUrd-substituted cells than in ordinal cells were observed, suggesting a possible involvement of X-ray-induced Auger phenomenon in iodine in DNA.« less

Investigation of the Structural Stability of Ion-Implanted Gd 2Ti 2-xSn xO 7 Pyrochlore-Type Oxides by Glancing Angle X-ray Absorption Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aluri, Esther Rani; Hayes, John R.; Walker, James D.S.

2016-03-24

Rare-earth titanate and stannate pyrochlore-type oxides have been investigated in the past for the sequestration of nuclear waste elements because of their resistance to radiation-induced structural damage. In order to enhance this property, it is necessary to understand the effect of radioactive decay of the incorporated actinide elements on the local chemical environment. In this study, Gd 2Ti 2–xSn xO 7 materials have been implanted with Au– ions to simulate radiation-induced structural damage. Glancing angle X-ray absorption near-edge spectroscopy (GA-XANES), glancing angle X-ray absorption fine structure (GA-EXAFS) analysis, and powder X-ray diffraction have been used to investigate changes in themore » local coordination environment of the metal atoms in the damaged surface layer. Examination of GA-XANES/EXAFS spectra from the implanted Gd 2Ti 2–xSn xO 7 materials collected at various glancing angles allowed for an investigation of how the local coordination environment around the absorbing atoms changed at different depths in the damaged surface layer. This study has shown the usefulness of GA-XANES to the examination of ion-implanted materials and has suggested that Gd 2Ti 2–xSn xO 7 becomes more susceptible to ion-beam-induced structural damage with increasing Sn concentration.« less

Experimental and first-principles calculation study of the pressure-induced transitions to a metastable phase in GaP O4 and in the solid solution AlP O4-GaP O4

NASA Astrophysics Data System (ADS)

Angot, E.; Huang, B.; Levelut, C.; Le Parc, R.; Hermet, P.; Pereira, A. S.; Aquilanti, G.; Frapper, G.; Cambon, O.; Haines, J.

2017-08-01

α -Quartz-type gallium phosphate and representative compositions in the AlP O4-GaP O4 solid solution were studied by x-ray powder diffraction and absorption spectroscopy, Raman scattering, and by first-principles calculations up to pressures of close to 30 GPa. A phase transition to a metastable orthorhombic high-pressure phase along with some of the stable orthorhombic C m c m CrV O4 -type material is found to occur beginning at 9 GPa at 320 ∘C in GaP O4 . In the case of the AlP O4-GaP O4 solid solution at room temperature, only the metastable orthorhombic phase was obtained above 10 GPa. The possible crystal structures of the high-pressure forms of GaP O4 were predicted from first-principles calculations and the evolutionary algorithm USPEX. A predicted orthorhombic structure with a P m n 21 space group with the gallium in sixfold and phosphorus in fourfold coordination was found to be in the best agreement with the combined experimental data from x-ray diffraction and absorption and Raman spectroscopy. This method is found to very powerful to better understand competition between different phase transition pathways at high pressure.

Synthesis of samarium doped gadolinium oxide nanorods, its spectroscopic and physical properties

NASA Astrophysics Data System (ADS)

Boopathi, G.; Gokul Raj, S.; Ramesh Kumar, G.; Mohan, R.; Mohan, S.

2018-06-01

One-dimensional samarium doped gadolinium oxide [Sm:Gd2O3] nanorods have been synthesized successfully through co-precipitation technique in aqueous solution. The as-synthesized and calcined products were characterized by using powder X-ray diffraction pattern, Fourier transform Raman spectroscopy, thermogravimetric/differential thermal analysis, scanning electron microscopy with energy-dispersive X-ray analysis, transmission electron microscopy, Fourier transform infrared spectroscopy, Ultraviolet-Visible spectrometry, photoluminescence spectrophotometer and X-ray photoelectron spectroscopy techniques. The obtained results are discussed in detailed manner.

Advanced Organic Solid States Materials. Volume 173. Materials Research Society Symposium Proceedings

DTIC Science & Technology

1990-08-08

for their collaboration in synthetic study. We also thank Prof. N. Kasai and Dr. Y. Kai for their collaboration in X - ray crystallographic study. We...substantially with the increasing amount of doping as monitored by the powder x - ray diffraction. After doping the sample was kept for at least one day...physical properties at different oxidation states in solution and in the solid state of tEDTB complexed with TCNQF4. The X ray crystal structure of

Efficient interface-induced effect of novel reduced graphene oxide-CoS heteronanostructures in enhancing photocatalytic acitivities

NASA Astrophysics Data System (ADS)

He, H.-Y.

2017-11-01

The interface-induced effects of heteronanostructures are attracting many attentions due to their potentials in photocatalysis applications. In this work, reduced graphene oxide-CoS (rGO-CoS) heteronanostructures were synthesized with a chemical method. The characterization of these nanomaterials was performed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectra, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and photocatalytic activities to understand the physical and chemical behavior of these materials. The effects of rGO/CoS ratio, initial solution pH, and H2O2 on the photodegradation of malachite green in a water were studied. The hybrids showed excellent sunlight-excited photocatalytic and Fenton-like photocatalytic activities to the dye, better than that of the CoS nanoparticles and enhanced as increasing rGO/CoS ratio and decreasing initial pH. The photodegradation rate constant, k obs, was determined under pseudo-first order conditions. The enhanced photoctalytic activities with rGO/CoS were ascribed to the enhanced charge transfer at the interface. The interface effect was confirmed by the calculations of band energy level and optical conductivity.

Ultrasound-induced capping of polystyrene on TiO2 nanoparticles by precipitation with compressed CO2 as antisolvent.

PubMed

Zhang, Jianling; Liu, Zhimin; Han, Buxing; Li, Junchun; Li, Zhonghao; Yang, Guanying

2005-06-01

In this work, a route for the synthesis of inorganic/polymer core/shell composite nanoparticles was proposed, which can be called the antisolvent-ultrasound method. Compressed CO2 was used as antisolvent to precipitate the polymer from its solution dispersed with inorganic nanoparticles, during which ultrasonic irradiation was used to induce the coating of precipitated polymers on the surfaces of the inorganic nanoparticles. TiO2/polystyrene (PS) core/shell nanocomposites have been successfully prepared using this method. The transmission electronic micrographs (TEM) of the obtained nanocomposites show that the TiO2 nanoparticles are coated by the PS shells, of which the thickness can be tuned by the pressure of CO2. The phase structure, absorption properties, and thermal stability of the composite were characterized by X-ray diffraction (XRD), UV-vis spectra, and thermogravimetry, respectively. The results of X-ray photoelectron spectra (XPS) indicate the formation of a strong interaction between PS and TiO2 nanoparticles in the resultant products. This method has some potential advantages for applications and may be easily applied to the preparation of a range of inorganic/polymer core/shell composite nanoparticles.

Origin of Pressure-induced Superconducting Phase in K xFe 2-ySe 2 studied by Synchrotron X-ray Diffraction and Spectroscopy

DOE PAGES

Yamamoto, Yoshiya; Yamaoka, Hitoshi; Tanaka, Masashi; ...

2016-08-08

Pressure dependence of the electronic and crystal structures of K xFe 2–ySe 2, which has pressure-induced two superconducting domes of SC I and SC II, was investigated by x-ray emission spectroscopy and diffraction. X-ray diffraction data show that compressibility along the c-axis changes around 12 GPa, where a new superconducting phase of SC II appears. This suggests a possible tetragonal to collapsed tetragonal phase transition. X-ray emission spectroscopy data also shows the change in the electronic structure around 12 GPa. These results can be explained by the scenario that the two SC domes under pressure originate from the change ofmore » Fermi surface topology. Lastly, our results here show the pronounced increase of the density of states near the Fermi surface under pressure with a structural phase transition, which can help address our fundamental understanding for the appearance of the SC II phase.« less

An easy-to-implement filter for separating photo-excited signals from topography in scanning tunneling microscopy.

PubMed

Wang, Kangkang; Rosenmann, Daniel; Holt, Martin; Winarski, Robert; Hla, Saw-Wai; Rose, Volker

2013-06-01

In order to achieve elemental and chemical sensitivity in scanning tunneling microscopy (STM), synchrotron x-rays have been applied to excite core-level electrons during tunneling. The x-ray photo-excitations result in tip currents that are superimposed onto conventional tunneling currents. While carrying important physical information, the varying x-ray induced currents can destabilize the feedback loop causing it to be unable to maintain a constant tunneling current, sometimes even causing the tip to retract fully or crash. In this paper, we report on an easy-to-implement filter circuit that can separate the x-ray induced currents from conventional tunneling currents, thereby allowing simultaneous measurements of topography and chemical contrasts. The filter and the schematic presented here can also be applied to other variants of light-assisted STM such as laser STM.

Measurement of the Energy and High-Pressure Dependence of X-ray-Induced Decomposition of Crystalline Strontium Oxalate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldberger, David; Evlyukhin, Egor; Cifligu, Petrika

We report measurements of the X-ray-induced decomposition of crystalline strontium oxalate (SrC2O4) as a function of energy and high pressure in two separate experiments. SrC2O4 at ambient conditions was irradiated with monochromatic synchrotron X-rays ranging in energy from 15 to 28 keV. A broad resonance of the decomposition yield was observed with a clear maximum when irradiating with ~20 keV X-rays and ambient pressure. Little or no decomposition was observed at 15 keV, which is below the Sr K-shell energy of 16.12 keV, suggesting that excitation of core electrons may play an important role in the destabilization of the C2O42–more » anion. A second experiment was performed to investigate the high-pressure dependence of the X-ray-induced decomposition of strontium oxalate at fixed energy. SrC2O4 was compressed in a diamond anvil cell (DAC) in the pressure range from 0 to 7.6 GPa with 1 GPa increments and irradiated in situ with 20 keV X-rays. A marked pressure dependence of the decomposition yield of SrC2O4 was observed with a decomposition yield maximum at around 1 GPa, suggesting that different crystal structures of the material play an important role in the decomposition process. This may be due in part to a phase transition observed near this pressure.« less

Measurement of the Energy and High-Pressure Dependence of X-ray-Induced Decomposition of Crystalline Strontium Oxalate.

PubMed

Goldberger, David; Evlyukhin, Egor; Cifligu, Petrika; Wang, Yonggang; Pravica, Michael

2017-09-28

We report measurements of the X-ray-induced decomposition of crystalline strontium oxalate (SrC 2 O 4 ) as a function of energy and high pressure in two separate experiments. SrC 2 O 4 at ambient conditions was irradiated with monochromatic synchrotron X-rays ranging in energy from 15 to 28 keV. A broad resonance of the decomposition yield was observed with a clear maximum when irradiating with ∼20 keV X-rays and ambient pressure. Little or no decomposition was observed at 15 keV, which is below the Sr K-shell energy of 16.12 keV, suggesting that excitation of core electrons may play an important role in the destabilization of the C 2 O 4 2- anion. A second experiment was performed to investigate the high-pressure dependence of the X-ray-induced decomposition of strontium oxalate at fixed energy. SrC 2 O 4 was compressed in a diamond anvil cell (DAC) in the pressure range from 0 to 7.6 GPa with 1 GPa increments and irradiated in situ with 20 keV X-rays. A marked pressure dependence of the decomposition yield of SrC 2 O 4 was observed with a decomposition yield maximum at around 1 GPa, suggesting that different crystal structures of the material play an important role in the decomposition process. This may be due in part to a phase transition observed near this pressure.

Speciation of platinum(IV) in nitric acid solutions.

PubMed

Vasilchenko, Danila; Tkachev, Sergey; Baidina, Iraida; Korenev, Sergey

2013-09-16

The speciation of platinum(IV) ions in nitric acid (6-15.8 M) solutions of H2[Pt(OH)6] has been studied by (195)Pt NMR and Raman spectroscopy. Series of aqua-hydroxo-nitrato complexes [Pt(L)(x)(NO3)(6-x)] (L = H2O or OH(-); x = 0, ..., 6) were found to exist in such solutions. The pair additivity model of chemical shifts and statistical theory were used to assign signals in NMR spectra to particular [Pt(L)(x)(NO3)(6-x)] species. Mononuclear hexanitratoplatinates(IV) have been isolated in solid state in substantial yield as pyridinium salt (PyH)2[Pt(NO3)6] and characterized by single-crystal X-ray diffraction. Aging of the platinum nitric acid solutions for more than 5-6 h results in oligomerization of [Pt(L)(x)(NO3)(6-x)] species and the formation of oligonuclear aqua-hydroxo-nitrato complexes with OH(-) and NO3(-) bridging ligands. Oligomeric platinum(IV) complexes with two and four nuclei were unambiguously detected by NMR on (195)Pt -enriched samples. Oligomers with even higher nuclearity were also detected. Dimeric anions [Pt2(μ-OH)2(NO3)8](2-) have been isolated as single crystals of tetramethylammonium salt and characterized by X-ray diffraction.

THE COMPARATIVE MUTAGENIC EFFECT OF ETHYLENIMINE, ULTRAVIOLET AND X-RAYS (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alikhanyan, S.I.; Zhdanova, N.I.

1960-07-11

The mutagenic effects of ethylenimine were determined by the use of Actinomyces alivaceus (the product of B/sub 12/ vitamin) and compared with ultraviolet, and x ray effects. The spores were exposed to high concentrations of ethylenimine (solution of 1: 1000) for various times (30 min, 1, 2, 3, 4, and 5 hr) and to diluted concentrations (1: 3000, produced by short-time exposure to a concentrated solution; lethality at various treatments is nearly identical. The results of the comparison with ultraviolet and x rays indicate a large advantage in the use of ethylenimine. Curves of reverse mutation frequencies indicate prevailing frequenciesmore » of ethylenimine mutations over ultraviolet. This shows that regardless of genetic background changes. the advantages of ethylenimine are retained. (R.V.J.)« less

High-compactness coating grown by plasma electrolytic oxidation on AZ31 magnesium alloy in the solution of silicate-borax

NASA Astrophysics Data System (ADS)

Shen, M. J.; Wang, X. J.; Zhang, M. F.

2012-10-01

A ceramic coating was formed on the surface of AZ31 magnesium alloy by plasma electrolytic oxidation (PEO) in the silicate solution with and without borax doped. The composition, morphology, elements and roughness as well as mechanical property of the coating were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and reciprocal-sliding tribometer. The results show that the PEO coating is mainly composed of magnesia. When using borax dope, boron element is permeating into the coating and the boron containing phase exist in the form of amorphous. In addition, the microhardness and compactness of the PEO coating are improved significantly due to doped borax.

X-ray driven reaction front dynamics at calcite-water interfaces

DOE PAGES

Laanait, Nouamane; Callagon, Erika Blanca R.; Zhang, Zhan; ...

2015-09-18

The interface of minerals with aqueous solutions is central to geochemical reactivity, hosting processes that span multiple spatiotemporal scales. Understanding such processes requires spatially and temporally resolved observations, and experimental controls that precisely manipulate the interfacial thermodynamic state. Using the intense radiation fields of a focused synchrotron X-ray beam, we drove dissolution at the calcite-aqueous interface and simultaneously probed the dynamics of the propagating reaction fronts using surface X-ray microscopy. Evolving surface structures are controlled by the time-dependent solution composition as characterized by a kinetic reaction model. At extreme disequilibria, the onset of reaction front instabilities was observed with velocitiesmore » of >30 nanometers per second. As a result, these instabilities are identified as a signature of transport-limited dissolution of calcite under extreme disequilibrium.« less

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

PubMed

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.

High Power Optical Coatings by Atomic Layer Deposition and Signatures of Laser-Induced Damage

DTIC Science & Technology

2012-08-28

diffraction angle 0 into crystal lattice spacing d by the Bragg condition, mX = 2d sin 0. Here X is the x - ray wavelength... angle x - ray diffraction (GAXRD) measurements, which were made at a fixed shallow incidence angle of 0.5°. Detector scans were done to measure the...was finished with 200 hafnia cycles m the fmal half period rather than 400. Crystallinity was measured by x - ray diffraction (XRD) with

X-Ray-induced Deuterium Enrichment of N-rich Organics in Protoplanetary Disks: An Experimental Investigation Using Synchrotron Light

NASA Astrophysics Data System (ADS)

Gavilan, Lisseth; Remusat, Laurent; Roskosz, Mathieu; Popescu, Horia; Jaouen, Nicolas; Sandt, Christophe; Jäger, Cornelia; Henning, Thomas; Simionovici, Alexandre; Lemaire, Jean Louis; Mangin, Denis; Carrasco, Nathalie

2017-05-01

The deuterium enrichment of organics in the interstellar medium, protoplanetary disks, and meteorites has been proposed to be the result of ionizing radiation. The goal of this study is to simulate and quantify the effects of soft X-rays (0.1-2 keV), an important component of stellar radiation fields illuminating protoplanetary disks, on the refractory organics present in the disks. We prepared tholins, nitrogen-rich organic analogs to solids found in several astrophysical environments, e.g., Titan’s atmosphere, cometary surfaces, and protoplanetary disks, via plasma deposition. Controlled irradiation experiments with soft X-rays at 0.5 and 1.3 keV were performed at the SEXTANTS beamline of the SOLEIL synchrotron, and were immediately followed by ex-situ infrared, Raman, and isotopic diagnostics. Infrared spectroscopy revealed the preferential loss of singly bonded groups (N-H, C-H, and R-N≡C) and the formation of sp3 carbon defects with signatures at ˜1250-1300 cm-1. Raman analysis revealed that, while the length of polyaromatic units is only slightly modified, the introduction of defects leads to structural amorphization. Finally, tholins were measured via secondary ion mass spectrometry to quantify the D, H, and C elemental abundances in the irradiated versus non-irradiated areas. Isotopic analysis revealed that significant D-enrichment is induced by X-ray irradiation. Our results are compared to previous experimental studies involving the thermal degradation and electron irradiation of organics. The penetration depth of soft X-rays in μm-sized tholins leads to volume rather than surface modifications: lower-energy X-rays (0.5 keV) induce a larger D-enrichment than 1.3 keV X-rays, reaching a plateau for doses larger than 5 × 1027 eV cm-3. Synchrotron fluences fall within the expected soft X-ray fluences in protoplanetary disks, and thus provide evidence of a new non-thermal pathway to deuterium fractionation of organic matter.

Structure of dimethylphenyl betaine hydrochloride studied by X-ray diffraction, DFT calculation, NMR and FTIR spectra

NASA Astrophysics Data System (ADS)

Szafran, M.; Katrusiak, A.; Dega-Szafran, Z.; Kowalczyk, I.

2013-01-01

The structure of dimethylphenyl betaine hydrochloride (1) has been studied by X-ray diffraction, DFT calculations, NMR and FTIR spectra. The crystals are monoclinic, space group P21/c. In the crystal, the Cl- anion is connected with protonated betaine through the O-H⋯Cl- hydrogen bond of 2.943(2) Å. The structures in the gas phase (2) and water solution (3) have been optimized by the B3LYP/6-311++G(d,p) approach and the geometrical results have been compared with the X-ray data of 1. The FTIR spectrum of the solid compound is consistent with the X-ray results. The probable assignments of the anharmonic experimental vibrational frequencies of the investigated chloride (1) based on the calculated harmonic frequencies in water solution (3) are proposed. The correlations between the experimental 1H and 13C NMR chemical shifts (δexp) of 1 in D2O and the magnetic isotropic shielding constants (σcalc) calculated by the GIAO/B3LYP/6-311G++(d,p) approach, using the screening solvation model (COSMO), δexp = a + b σcalc, for optimized molecule 3 in water solution are linear and correctly reproduce the experimental chemical shifts.

Electronic Structure of the Organic Semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from Soft X-ray Spectroscopies and Density Functional Theory Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeMasi, A.; Piper, L; Zhang, Y

2008-01-01

The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq3) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq3, and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studiesmore » and the present data reveal the presence of clear photon-induced damage in the former.« less

X-ray absorption investigation of local structural disorder in Ni 1-xFe x (x=0.10, 0.20, 0.35, and 0.50) alloys

DOE PAGES

Zhang, Fuxiang X.; Jin, Ke; Zhao, Shijun; ...

2017-04-27

Defect energetics in structural materials has long been recognized to be affected by specific alloy compositions. Significantly enhanced radiation resistance has recently been observed in concentrated solid-solution alloys. However, the link between local structural disorder and modified defect dynamics in solid solutions remains unclear. To reveal the atomic-level lattice distortion, the local structures of Ni and Fe in Ni 1-xFe x (x=0.1, 0.2, 0.35 and 0.5) solid solution alloys were measured with extended X-ray absorption fine structure (EXAFS) technique. The lattice constant and the first-neighbor distances increase with the increase of Fe content in the solid solutions. EXAFS measurements havemore » revealed that the bond length of Fe with surrounding atoms is 0.01-0.03 larger than that of Ni in the alloy systems. Debye-Waller factor of the Fe-Fe bonds in all the systems is also slightly larger than that of the Ni-Ni bond. EXAFS fitting suggests that the local structural disorder is enhanced with the addition of Fe elements in the solid solution. The local bonding environments from ab initio calculation are in good agreement with the experimental results, which suggest that the Fe has a larger first-neighbor bonding distance than that of Ni, and thus Ni atom inside the Ni-Fe solid solution alloys undergoes compressive strain.« less

X-ray absorption investigation of local structural disorder in Ni 1-xFe x (x=0.10, 0.20, 0.35, and 0.50) alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Fuxiang X.; Jin, Ke; Zhao, Shijun

Defect energetics in structural materials has long been recognized to be affected by specific alloy compositions. Significantly enhanced radiation resistance has recently been observed in concentrated solid-solution alloys. However, the link between local structural disorder and modified defect dynamics in solid solutions remains unclear. To reveal the atomic-level lattice distortion, the local structures of Ni and Fe in Ni 1-xFe x (x=0.1, 0.2, 0.35 and 0.5) solid solution alloys were measured with extended X-ray absorption fine structure (EXAFS) technique. The lattice constant and the first-neighbor distances increase with the increase of Fe content in the solid solutions. EXAFS measurements havemore » revealed that the bond length of Fe with surrounding atoms is 0.01-0.03 larger than that of Ni in the alloy systems. Debye-Waller factor of the Fe-Fe bonds in all the systems is also slightly larger than that of the Ni-Ni bond. EXAFS fitting suggests that the local structural disorder is enhanced with the addition of Fe elements in the solid solution. The local bonding environments from ab initio calculation are in good agreement with the experimental results, which suggest that the Fe has a larger first-neighbor bonding distance than that of Ni, and thus Ni atom inside the Ni-Fe solid solution alloys undergoes compressive strain.« less

Establishment of new design criteria for GlidCop ® X-ray absorbers

DOE PAGES

Collins, Jeff T.; Nudell, Jeremy; Navrotski, Gary; ...

2017-02-20

Here, an engineering research program has been conducted at the Advanced Photon Source (APS) in order to determine the thermomechanical conditions that lead to crack formation in GlidCop ®, a material commonly used to fabricate X-ray absorbers at X-ray synchrotron facilities. This dispersion-strengthened copper alloy is a proprietary material and detailed technical data of interest to the synchrotron community is limited. The results from the research program have allowed new design criteria to be established for GlidCop ® X-ray absorbers based upon the thermomechanically induced fatigue behavior of the material. X-ray power from APS insertion devices was used to exposemore » 30 GlidCop ® samples to 10000 thermal loading cycles each under various beam power conditions, and all of the samples were metallurgically examined for crack presence/geometry. In addition, an independent testing facility was hired to measure temperature-dependent mechanical data and uniaxial mechanical fatigue data for numerous GlidCop ® samples. Data from these studies support finite element analysis (FEA) simulation and parametric models, allowing the development of a thermal fatigue model and the establishment of new design criteria so that the thermomechanically induced fatigue life of X-ray absorbers may be predicted. It is also demonstrated how the thermal fatigue model can be used as a tool to geometrically optimize X-ray absorber designs.« less

Sub-mSV breast XACT scanner: concept and design

NASA Astrophysics Data System (ADS)

Tang, Shanshan; Ren, Liqiang; Samant, Pratik; Chen, Jian; Liu, Hong; Xiang, Liangzhong

2016-04-01

Excessive exposure to radiation increases the risk of cancer. We present the concept and design of a new imaging paradigm, X-ray induced acoustic computed tomography (XACT). Applying this innovative technology to breast imaging, one single X-ray exposure can generate a 3D acoustic image, which dramatically reduces the radiation dose to patients when compared to beast CT. A theoretical model is developed to analyze the sensitivity of XACT. A noise equivalent pressure model is used for calculating the minimal radiation dose in XACT imaging. Furthermore, K-Wave simulation is employed to study the acoustic wave propagation in breast tissue. Theoretical analysis shows that the X-ray induced acoustic signal has a 100% relative sensitivity to the X-ray absorption (given that the percentage change in the X-ray absorption coefficient yields the same percentage change in the acoustic signal amplitude), but not to X-ray scattering. The final detection sensitivity is primarily limited by the thermal noise. The radiation dose can be reduced by a factor of 100 compared with the newly FDA approved breast CT. Reconstruction result shows that breast calcification with diameter of 80 μm can be observed in XACT image by using ultrasound transducers with 5.5 MHz center frequency. Therefore, with the proposed innovative technology, one can potentially reduce radiation dose to patient in breast imaging as compared with current x-ray modalities.

Establishment of new design criteria for GlidCop ® X-ray absorbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, Jeff T.; Nudell, Jeremy; Navrotski, Gary

Here, an engineering research program has been conducted at the Advanced Photon Source (APS) in order to determine the thermomechanical conditions that lead to crack formation in GlidCop ®, a material commonly used to fabricate X-ray absorbers at X-ray synchrotron facilities. This dispersion-strengthened copper alloy is a proprietary material and detailed technical data of interest to the synchrotron community is limited. The results from the research program have allowed new design criteria to be established for GlidCop ® X-ray absorbers based upon the thermomechanically induced fatigue behavior of the material. X-ray power from APS insertion devices was used to exposemore » 30 GlidCop ® samples to 10000 thermal loading cycles each under various beam power conditions, and all of the samples were metallurgically examined for crack presence/geometry. In addition, an independent testing facility was hired to measure temperature-dependent mechanical data and uniaxial mechanical fatigue data for numerous GlidCop ® samples. Data from these studies support finite element analysis (FEA) simulation and parametric models, allowing the development of a thermal fatigue model and the establishment of new design criteria so that the thermomechanically induced fatigue life of X-ray absorbers may be predicted. It is also demonstrated how the thermal fatigue model can be used as a tool to geometrically optimize X-ray absorber designs.« less

Synergistic effect of heat shock protein 90 inhibitor, 17-allylamino-17-demethoxygeldanamycin and X-rays, but not carbon-ion beams, on lethality in human oral squamous cell carcinoma cells

PubMed Central

Musha, Atsushi; Yoshida, Yukari; Takahashi, Takeo; Ando, Koichi; Funayama, Tomoo; Kobayashi, Yasuhiko; Negishi, Akihide; Yokoo, Satoshi; Nakano, Takashi

2012-01-01

The purpose of this study is to clarify the effect of a heat shock protein 90 inhibitor, 17-allylamino-17-demethoxygeldanamycin (17-AAG), in combination with X-rays or carbon-ion beams on cell killing in human oral squamous cell carcinoma LMF4 cells. Cell survival was measured by colony formation assay. Cell-cycle distribution was analyzed by flow cytometry. Expression of DNA repair-related proteins was investigated by western blotting. The results showed 17-AAG to have synergistic effects on cell lethality with X-rays, but not with carbon-ion beams. The 17-AAG decreased G2/M arrest induced by X-rays, but not by carbon-ion beams. Both X-ray and carbon-ion irradiation up-regulated expression of non-homologous end-joining-associated proteins, Ku70 and Ku80, but 17-AAG inhibited only X-ray-induced up-regulation of these proteins. These results show that 17-AAG with X-rays releases G2/M phase arrest; cells carrying misrepaired DNA damage then move on to the G1 phase. We demonstrate, for the first time, that the radiosensitization effect of 17-AAG is not seen with carbon-ion beams because 17-AAG does not affect these changes. PMID:22843619

First-principles calculations of K-shell X-ray absorption spectra for warm dense nitrogen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zi; Zhang, Shen; Kang, Wei

2016-05-15

X-ray absorption spectrum is a powerful tool for atomic structure detection on warm dense matter. Here, we perform first-principles molecular dynamics and X-ray absorption spectrum calculations on warm dense nitrogen along a Hugoniot curve. From the molecular dynamics trajectory, the detailed atomic structures are examined for each thermodynamical condition. The K-shell X-ray absorption spectrum is calculated, and its changes with temperature and pressure along the Hugoniot curve are discussed. The warm dense nitrogen systems may contain isolated nitrogen atoms, N{sub 2} molecules, and nitrogen clusters, which show quite different contributions to the total X-ray spectrum due to their different electronmore » density of states. The changes of X-ray spectrum along the Hugoniot curve are caused by the different nitrogen structures induced by the temperature and the pressure. Some clear signatures on X-ray spectrum for different thermodynamical conditions are pointed out, which may provide useful data for future X-ray experiments.« less

Two-colour hard X-ray free-electron laser with wide tunability.

PubMed

Hara, Toru; Inubushi, Yuichi; Katayama, Tetsuo; Sato, Takahiro; Tanaka, Hitoshi; Tanaka, Takashi; Togashi, Tadashi; Togawa, Kazuaki; Tono, Kensuke; Yabashi, Makina; Ishikawa, Tetsuya

2013-01-01

Ultrabrilliant, femtosecond X-ray pulses from X-ray free-electron lasers (XFELs) have promoted the investigation of exotic interactions between intense X-rays and matters, and the observation of minute targets with high spatio-temporal resolution. Although a single X-ray beam has been utilized for these experiments, the use of multiple beams with flexible and optimum beam parameters should drastically enhance the capability and potentiality of XFELs. Here we show a new light source of a two-colour double-pulse (TCDP) XFEL in hard X-rays using variable-gap undulators, which realizes a large and flexible wavelength separation of more than 30% with an ultraprecisely controlled time interval in the attosecond regime. Together with sub-10-fs pulse duration and multi-gigawatt peak powers, the TCDP scheme enables us to elucidate X-ray-induced ultrafast transitions of electronic states and structures, which will significantly contribute to the advancement of ultrafast chemistry, plasma and astronomical physics, and quantum X-ray optics.

Evaluation of White Bentonite Modified by Acid Attack

NASA Astrophysics Data System (ADS)

Andrade, C. G. Bastos; Fermino, D. M.; Fernandes, M. G.; Valenzuela-Diaz, F. R.

For industrial use, the smectite clays must be cleared of impurities, usually obtained by acid modification, using a high concentration solution of inorganic acid at temperatures under boiling point. In the present paper, a sample of white bentonite from Paraiba, Brazil, was modified by hydrochloric acid under moderate conditions (90°C, reaction times of 1, 6, 12, 18 and 24hours in close reactor, concentration of the aqueous solution of hydrochloric acid 1.5 M, acid solution/clay ratio of 1g/10mL). The purpose of these attacks is to reduce the concentration of impurities with minimal change in the clay minerals structure. The modified samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Cation Exchange Capacity (CEC), Stereomicroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Detector (EDS). Thus, this modified bentonite tends to be a good economic and environmental alternative in manufacturing of products with high added value such as cosmetics and polymer/clay nanocomposites.

Polymer X-ray refractive nano-lenses fabricated by additive technology.

PubMed

Petrov, A K; Bessonov, V O; Abrashitova, K A; Kokareva, N G; Safronov, K R; Barannikov, A A; Ershov, P A; Klimova, N B; Lyatun, I I; Yunkin, V A; Polikarpov, M; Snigireva, I; Fedyanin, A A; Snigirev, A

2017-06-26

The present work demonstrates the potential applicability of additive manufacturing to X-Ray refractive nano-lenses. A compound refractive lens with a radius of 5 µm was produced by the two-photon polymerization induced lithography. It was successfully tested at the X-ray microfocus laboratory source and a focal spot of 5 μm was measured. An amorphous nature of polymer material combined with the potential of additive technologies may result in a significantly enhanced focusing performance compared to the best examples of modern X-ray compound refractive lenses.

Diagnosing radiative shocks from deuterium and tritium implosions on NIF.

PubMed

Pak, A; Divol, L; Weber, S; Döppner, T; Kyrala, G A; Kilne, J; Izumi, N; Glenn, S; Ma, T; Town, R P; Bradley, D K; Glenzer, S H

2012-10-01

During the recent ignition tuning campaign at the National Ignition Facility, layered cryogenic deuterium and tritium capsules were imploded via x-ray driven ablation. The hardened gated x-ray imager diagnostic temporally and spatially resolves the x-ray emission from the core of the capsule implosion at energies above ~8 keV. On multiple implosions, ~200-400 ps after peak compression a spherically expanding radiative shock has been observed. This paper describes the methods used to characterize the radial profile and rate of expansion of the shock induced x-ray emission.

X-ray diffraction from shock-loaded polycrystals.

PubMed

Swift, Damian C

2008-01-01

X-ray diffraction was demonstrated from shock-compressed polycrystalline metals on nanosecond time scales. Laser ablation was used to induce shock waves in polycrystalline foils of Be, 25-125 microm thick. A second laser pulse was used to generate a plasma x-ray source by irradiation of a Ti foil. The x-ray source was collimated to produce a beam of controllable diameter, which was directed at the Be sample. X-rays were diffracted from the sample, and detected using films and x-ray streak cameras. The diffraction angle was observed to change with shock pressure. The diffraction angles were consistent with the uniaxial (elastic) and isotropic (plastic) compressions expected for the loading conditions used. Polycrystalline diffraction will be used to measure the response of the crystal lattice to high shock pressures and through phase changes.

Radiation hardening of gated x-ray imagers for the National Ignition Facility (invited).

PubMed

Bell, P M; Bradley, D K; Kilkenny, J D; Conder, A; Cerjan, C; Hagmann, C; Hey, D; Izumi, N; Moody, J; Teruya, A; Celeste, J; Kimbrough, J; Khater, H; Eckart, M J; Ayers, J

2010-10-01

The National Ignition Facility will soon be producing x-ray flux and neutron yields higher than any produced in laser driven implosion experiments in the past. Even a non-igniting capsule will require x-ray imaging of near burning plasmas at 10(17) neutrons, requiring x-ray recording systems to work in more hostile conditions than we have encountered in past laser facilities. We will present modeling, experimental data and design concepts for x-ray imaging with electronic recording systems for this environment (ARIANE). A novel instrument, active readout in a nuclear environment, is described which uses the time-of-flight difference between the gated x-ray signal and the neutron which induces a background signal to increase the yield at which gated cameras can be used.

Developable images produced by x-rays using the nickel-hypophosphite system. 2: Exposure and development parameters for sodium hypophosphite

NASA Technical Reports Server (NTRS)

May, C. E.; Philipp, W. H.; Marsik, S. J.

1972-01-01

Crystalline sodium hypophosphite was X-irradiated and then treated with an ammoniacal nickel hypophosphite solution. Treatment resulted in the precipitation of nickel metal. The yield of nickel metal varied directly with particle size, sample weight, X-ray voltage, target current, exposure time, and development time. These findings show the process to be potentially useful in X-ray type photography. The half-life for the latent image species was found to be relatively short; but this is not critical in most X-ray photography applications. Furthermore, the work can be interpreted on the basis that a hydrogen atom is involved in the mechanism and indicates that the autocatalytic development step may be self-poisoning.

Advancement of X-Ray Microscopy Technology and its Application to Metal Solidification Studies

NASA Technical Reports Server (NTRS)

Kaukler, William F.; Curreri, Peter A.

1996-01-01

The technique of x-ray projection microscopy is being used to view, in real time, the structures and dynamics of the solid-liquid interface during solidification. By employing a hard x-ray source with sub-micron dimensions, resolutions of 2 micrometers can be obtained with magnifications of over 800 X. Specimen growth conditions need to be optimized and the best imaging technologies applied to maintain x-ray image resolution, contrast and sensitivity. It turns out that no single imaging technology offers the best solution and traditional methods like radiographic film cannot be used due to specimen motion (solidification). In addition, a special furnace design is required to permit controlled growth conditions and still offer maximum resolution and image contrast.

Phase and structural behavior of SmAlO{sub 3}–RAlO{sub 3} (R = Eu, Gd) systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohon, N.; Vasylechko, L., E-mail: crystal-lov@polynet.lviv.ua; Prots, Yu.

2014-02-01

Highlights: • Continuous solid solutions exist in the SmAlO{sub 3}–RAlO{sub 3} (R = Eu, Gd) systems. • Lattice parameter crossover was found in solid solutions Sm{sub 1−x}R{sub x}AlO{sub 3} (R = Eu, Gd). • Thermally induced lattice crossovers occur in Sm{sub 0.9}R{sub 0.1}AlO{sub 3} at elevated temperatures. • First-order structural phase transition Pbnm↔R3{sup ¯}c was found in Sm{sub 1−x}R{sub x}AlO{sub 3} (R = Eu, Gd). • Phase diagram of the systems SmAlO{sub 3}–EuAlO{sub 3} and SmAlO{sub 3}–GdAlO{sub 3} has been constructed. - Abstract: Phase and structural behavior in the SmAlO{sub 3}–RAlO{sub 3} (R = Eu, Gd) systems has been studiedmore » in a whole concentration range by means of laboratory X-ray diffraction, in situ synchrotron powder diffraction and differential thermal analysis techniques. Continuous solid solutions with orthorhombic perovskite structure have been found in both systems. Peculiarity of the solid solutions of Sm{sub 1−x}Eu{sub x}AlO{sub 3} and Sm{sub 1−x}Gd{sub x}AlO{sub 3} is the existence of two lattice parameter crossovers in each system occurred at x{sub Eu} = 0.07 and 0.62 and at x{sub Gd} = 0.04 and 0.33, respectively. The temperature induced lattice crossovers in the Sm{sub 0.9}Eu{sub 0.1}AlO{sub 3} and Sm{sub 0.9}Gd{sub 0.1}AlO{sub 3} samples have been found at 387 and 922 K and at 501 and 894 K. First-order reversible structural phase transformations Pbnm↔R3{sup ¯}c have been detected in both systems at the elevated temperatures. The temperatures of these transitions increase linearly with the decreasing of the samarium content. Phase diagrams of the pseudo-binary systems SmAlO{sub 3}–EuAlO{sub 3} and SmAlO{sub 3}–GdAlO{sub 3} have been constructed.« less

Ageing and thermal recovery of paramagnetic centers induced by electron irradiation in yttria-stabilized zirconia

NASA Astrophysics Data System (ADS)

Costantini, J. M.; Beuneu, F.

We have used electron spin resonance spectroscopy to study the defects induced in yttria-stabilized zirconia (YSZ) single crystals by 2.5-MeV electron irradiations. Two paramagnetic centers are produced: the first one with an axial <111> symmetry is similar to the trigonal Zr3+ electron center (T center) found after X-ray irradiation or thermo-chemical reduction, whereas the second one is a new oxygen hole center with an axial <100> symmetry different from the orthorhombic O- center induced by X-ray irradiation. At a fluence around 10(18) e/cm(2) , both centers are bleached out near 600 K, like the corresponding X-ray induced defects. At a fluence around 10(19) e/cm(2) , defects are much more stable, since complete thermal bleaching occurs near 1000 K. Accordingly, ageing of as-irradiated samples shows that high-dose defects at more stable than the low-dose ones.

Atmospheric electron-induced x-ray spectrometer development

NASA Technical Reports Server (NTRS)

Wilcox, Jaroslava Z.; Urgiles, Eduardo; Toda, Risaku; Crisp, Joy

2005-01-01

This paper extends the work reported at the IEEE Aerospace conference in 2001 and 2003 where the concept and progress in the development of the so called atmospheric Electron X-ray Spectrometer (AEXS) has been described.

Pulsed electrodeposition for the synthesis of strontium-substituted calcium phosphate coatings with improved dissolution properties.

PubMed

Drevet, Richard; Benhayoune, Hicham

2013-10-01

Strontium-substituted calcium phosphate coatings are synthesized by pulsed electrodeposition on titanium alloy (Ti6Al4V) substrates. Experimental conditions of the process are optimized in order to obtain a coating with a 5% atomic substitution of calcium by strontium which corresponds to the best observations on the osteoblast cells activity and on the osteoclast cells proliferation. The physical and chemical characterizations of the obtained coating are carried out by scanning electron microscopy associated to energy dispersive X-ray spectroscopy (EDXS) for X-ray microanalysis and the structural characterization of the coating is carried out by X-ray diffraction. The in vitro dissolution/precipitation properties of the coated substrates are investigated by immersion into Dulbecco's Modified Eagle Medium (DMEM) from 1h to 14 days. The calcium, phosphorus and strontium concentrations variations in the biological liquid are assessed by Induced Coupled Plasma - Atomic Emission Spectroscopy for each immersion time. The results show that under specific experimental conditions, the electrodeposition process is suitable to synthesize strontium-substituted calcium phosphate coatings. Moreover, the addition of hydrogen peroxide (H2O2) into the electrolytic solution used in the process allows us to observe a control of the strontium release during the immersion of the prosthetic materials into DMEM. © 2013.

Gas Accretion onto a Supermassive Black Hole: A Step to Model AGN Feedback

NASA Astrophysics Data System (ADS)

Nagamine, K.; Barai, P.; Proga, D.

2012-08-01

We study gas accretion onto a supermassive black hole (SMBH) using the 3D SPH code GADGET-3 on scales of 0.1-200 pc. First we test our code with the spherically symmetric, adiabatic Bondi accretion problem. We find that our simulation can reproduce the expected Bondi accretion flow very well for a limited amount of time until the effect of the outer boundary starts to be visible. We also find artificial heating of gas near the inner accretion boundary due to the artificial viscosity of SPH. Second, we implement radiative cooling and heating due to X-rays, and examine the impact of thermal feedback by the central X-ray source. The accretion flow roughly follows the Bondi solution for low central X-ray luminosities; however, the flow starts to exhibit non-spherical fragmentation due to the thermal instability for a certain range of central LX, and a strong overall outflow develops for greater LX. The cold gas develops filamentary structures that fall into the central SMBH, whereas the hot gas tries to escape through the channels in between the cold filaments. Such fragmentation of accreting gas can assist in the formation of clouds around AGN, induce star-formation, and contribute to the observed variability of narrow-line regions.

Bioaccumulation characterization of uranium by a novel Streptomyces sporoverrucosus dwc-3.

PubMed

Li, Xiaolong; Ding, Congcong; Liao, Jiali; Du, Liang; Sun, Qun; Yang, Jijun; Yang, Yuanyou; Zhang, Dong; Tang, Jun; Liu, Ning

2016-03-01

The biosorption mechanisms of uranium on an aerobic bacterial strain Streptomyces sporoverrucosus dwc-3, isolated from a potential disposal site for (ultra-)low uraniferous radioactive waste in Southwest China, were evaluated by using transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), proton induced X-ray emission (PIXE) and enhanced proton backscattering spectrometry (EPBS). Approximately 60% of total uranium at an initial concentration of 10mg/L uranium nitrate solution could be absorbed on 100mg S. sporoverrucosus dwc-3 with an adsorption capacity of more than 3.0mg/g (wet weight) after 12hr at room temperature at pH3.0. The dynamic biosorption process of S. sporoverrucosus dwc-3 for uranyl ions was well described by a pseudo second-order model. S. sporoverrucosus dwc-3 could accumulate uranium on cell walls and within the cell, as revealed by SEM and TEM analysis as well as EDX spectra. XPS and FT-IR analysis further suggested that the absorbed uranium was bound to amino, phosphate and carboxyl groups of the cells. Additionally, PIXE and EPBS results confirmed that ion exchange also contributed to the adsorption process of uranium. Copyright © 2015. Published by Elsevier B.V.

Note: A novel method for in situ loading of gases via x-ray induced chemistry

NASA Astrophysics Data System (ADS)

Pravica, Michael; Bai, Ligang; Park, Changyong; Liu, Yu; Galley, Martin; Robinson, John; Bhattacharya, Neelanjan

2011-10-01

We have developed and demonstrated a novel method to load oxygen in a sealed diamond anvil cell via the x-ray induced decomposition of potassium chlorate. By irradiating a pressurized sample of an oxidizer (KClO3) with either monochromatic or white beam x-rays from the Advanced Photon Source at ambient temperature and variable pressure, we succeeded in creating a localized region of molecular oxygen surrounded by unreacted sample which was confirmed via Raman spectroscopy. We anticipate that this technique will be useful in loading even more challenging, difficult-to-load gases such as hydrogen and also to load multiple gases.

Note: A novel method for in situ loading of gases via x-ray induced chemistry.

PubMed

Pravica, Michael; Bai, Ligang; Park, Changyong; Liu, Yu; Galley, Martin; Robinson, John; Bhattacharya, Neelanjan

2011-10-01

We have developed and demonstrated a novel method to load oxygen in a sealed diamond anvil cell via the x-ray induced decomposition of potassium chlorate. By irradiating a pressurized sample of an oxidizer (KClO(3)) with either monochromatic or white beam x-rays from the Advanced Photon Source at ambient temperature and variable pressure, we succeeded in creating a localized region of molecular oxygen surrounded by unreacted sample which was confirmed via Raman spectroscopy. We anticipate that this technique will be useful in loading even more challenging, difficult-to-load gases such as hydrogen and also to load multiple gases.

Report on the 18th International Conference on X-ray and Inner-Shell Processes (X99).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gemmell, D. S.; Physics

2000-01-01

The 18th conference of the series served as a forum for discussing fundamental issues in the field of x-ray and inner-shell processes and their application in various disciplines of science and technology. Special emphasis was given to the opportunities offered by modern synchrotron x-ray sources. The program included plenary talks, progress reports and poster presentations relating to new developments in the field of x-ray and inner-shell processes. The range of topics included: X-ray interactions with atoms, molecules, clusters, surfaces and solids; Decay processes for inner-shell vacancies; X-ray absorption and emission spectroscopy - Photoionization processes; Phenomena associated with highly charged ionsmore » and collisions with energetic particles; Electron-spin and -momentum spectroscopy; X-ray scattering and spectroscopy in the study of magnetic systems; Applications in materials science, biology, geosciences, and other disciplines; Elastic and inelastic x-ray scattering processes in atoms and molecules; Threshold phenomena (post-collision interaction, resonant Raman processes, etc.); Nuclear absorption and scattering of x-rays; 'Fourth-generation' x-ray sources; Processes exploiting the polarization and coherence properties of x-ray beams; Developments in experimental techniques (x-ray optics, temporal techniques, detectors); Microscopy, spectromicroscopy, and various imaging techniques; Non-linear processes and x-ray lasers; Ionization and excitation induced by charged particles and by x-rays; and Exotic atoms (including 'hollow' atoms and atoms that contain 'exotic' particles).« less

Condensed, solution and gas phase behaviour of mono- and dinuclear 2,6-diacetylpyridine (dap) hydrazone copper complexes probed by X-ray, mass spectrometry and theoretical calculations.

PubMed

Neto, Brenno A D; Viana, Barbara F L; Rodrigues, Thyago S; Lalli, Priscila M; Eberlin, Marcos N; da Silva, Wender A; de Oliveira, Heibbe C B; Gatto, Claudia C

2013-08-28

We describe the synthesis of novel mononuclear and dinuclear copper complexes and an investigation of their behaviour in solution using mass spectrometry (ESI-MS and ESI-MS/MS) and in the solid state using X-ray crystallography. The complexes were synthesized from two widely used diacetylpryridine (dap) ligands, i.e. 2,6-diacetylpyridinebis(benzoic acid hydrazone) and 2,6-diacetylpyridinebis(2-aminobenzoic acid hydrazone). Theoretical calculations (DFT) were used to predict the complex geometries of these new structures, their equilibrium in solution and energies associated with the transformations.

Chemical bonding in aqueous hexacyano cobaltate from photon- and electron-detection perspectives

PubMed Central

Lalithambika, Sreeju Sreekantan Nair; Atak, Kaan; Seidel, Robert; Neubauer, Antje; Brandenburg, Tim; Xiao, Jie; Winter, Bernd; Aziz, Emad F.

2017-01-01

The electronic structure of the [Co(CN)6]3− complex dissolved in water is studied using X-ray spectroscopy techniques. By combining electron and photon detection methods from the solutions ionized or excited by soft X-rays we experimentally identify chemical bonding between the metal center and the CN ligand. Non-resonant photoelectron spectroscopy provides solute electron binding energies, and nitrogen 1 s and cobalt 2p resonant core-level photoelectron spectroscopy identifies overlap between metal and ligand orbitals. By probing resonances we are able to qualitatively determine the ligand versus metal character of the respective occupied and non-occupied orbitals, purely by experiment. For the same excitations we also detect the emitted X-rays, yielding the complementary resonant inelastic X-ray scattering spectra. For a quantitative interpretation of the spectra, we perform theoretical electronic-structure calculations. The latter provide both orbital energies and orbital character which are found to be in good agreement with experimental energies and with experimentally inferred orbital mixing. We also report calculated X-ray absorption spectra, which in conjunction with our orbital-structure analysis, enables us to quantify various bonding interactions with a particular focus on the water-solvent – ligand interaction and the strength of π-backbonding between metal and ligand. PMID:28098216

Increased γ-H2A.X Intensity in Response to Chronic Medium-Dose-Rate γ-Ray Irradiation

PubMed Central

Sugihara, Takashi; Murano, Hayato; Tanaka, Kimio

2012-01-01

Background The molecular mechanisms of DNA repair following chronic medium-dose-rate (MDR) γ-ray-induced damage remain largely unknown. Methodology/Principal Findings We used a cell function imager to quantitatively measure the fluorescence intensity of γ-H2A.X foci in MDR (0.015 Gy/h and 0.06 Gy/h) or high-dose-rate (HDR) (54 Gy/h) γ-ray irradiated embryonic fibroblasts derived from DNA-dependent protein kinase mutated mice (scid/scid mouse embryonic fibroblasts (scid/scid MEFs)). The obtained results are as follows: (1) Automatic measurement of the intensity of radiation-induced γ-H2A.X foci by the cell function imager provides more accurate results compared to manual counting of γ-H2A.X foci. (2) In high-dose-rate (HDR) irradiation, γ-H2A.X foci with high fluorescence intensity were observed at 1 h after irradiation in both scid/scid and wild-type MEFs. These foci were gradually reduced through de-phosphorylation at 24 h or 72 h after irradiation. Furthermore, the fluorescence intensity at 24 h increased to a significantly greater extent in scid/scid MEFs than in wild-type MEFs in the G1 phase, although no significant difference was observed in G2/M-phase MEFs, suggesting that DNA-PKcs might be associated with non-homologous-end-joining-dependent DNA repair in the G1 phase following HDR γ-ray irradiation. (3) The intensity of γ-H2A.X foci for continuous MDR (0.06 Gy/h and 0.015 Gy/h) irradiation increased significantly and in a dose-dependent fashion. Furthermore, unlike HDR-irradiated scid/scid MEFs, the intensity of γ-H2A.X foci in MDR-irradiated scid/scid MEFs showed no significant increase in the G1 phase at 24 h, indicating that DNA repair systems using proteins other than DNA-PKcs might induce cell functioning that are subjected to MDR γ-ray irradiation. Conclusions Our results indicate that the mechanism of phosphorylation or de-phosphorylation of γ-H2A.X foci induced by chronic MDR γ-ray irradiation might be different from those induced by HDR γ-ray irradiation. PMID:23028931

Water-induced nanochannel networks in self-assembled block ionomers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mineart, Kenneth P.; Al-Mohsin, Heba A.; Lee, Byeongdu

2016-03-07

Block ionomers cast from solution exhibit solvent-templated morphologies that can be altered by solvent-vapor annealing. When cast from a mixed solvent, a midblock-sulfonated pentablock ion- omer self-assembles into spherical ionic microdomains that are loosely connected. Upon exposure to liquid water, nanoscale channels irreversibly develop between the microdomains due to swelling and form a continuous mesoscale network. We use electron tomography and real-time X-ray scat- tering to follow this transformation and show that the resultant morphology provides a highly effec- tive diffusive pathway.

Preliminary small-angle X-ray scattering and X-ray diffraction studies of the BTB domain of lola protein from Drosophila melanogaster

NASA Astrophysics Data System (ADS)

Boyko, K. M.; Nikolaeva, A. Yu.; Kachalova, G. S.; Bonchuk, A. N.; Dorovatovskii, P. V.; Popov, V. O.

2017-11-01

The Drosophila genome has several dozens of transcription factors (TTK group) containing BTB domains assembled into octamers. The LOLA protein belongs to this family. The purification, crystallization, and preliminary X-ray diffraction and small-angle X-ray scattering (SAXS) studies of the BTB domain of this protein are reported. The crystallization conditions were found by the vapor-diffusion technique. A very low diffraction resolution (8.7 Å resolution) of the crystals was insufficient for the determination of the threedimensional structure of the BTB domain. The SAXS study demonstrated that the BTB domain of the LOLA protein exists as an octamer in solution.

X-ray source for mammography

DOEpatents

Logan, Clinton M.

1994-01-01

An x-ray source utilizing anode material which shifts the output spectrum to higher energy and thereby obtains higher penetrating ability for screening mammography application, than the currently utilized anode material. The currently used anode material (molybdenum) produces an energy x-ray spectrum of 17.5/19.6 keV, which using the anode material of this invention (e.g. silver, rhodium, and tungsten) the x-ray spectrum would be in the 20-35 keV region. Thus, the anode material of this invention provides for imaging of breasts with higher than average x-ray opacity without increase of the radiation dose, and thus reduces the risk of induced breast cancer due to the radiation dose administered for mammograms.

Repair and recombination of X-irradiated plasmids in Xenopus laevis oocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sweigert, S.E.; Carroll, D.

1990-11-01

Plasmid DNA substrates were X-irradiated and injected into the nuclei of Xenopus laevis oocytes. After incubation for 20 h, DNA was recovered from the oocytes and analyzed simultaneously for repair and for intermolecular homologous recombination by electrophoresis and bacterial transformation. Oocyte-mediated repair of DNA strand breaks was observed with both methods. Using a repair-deficient mutant Escherichia coli strain and its repair-proficient parent as hosts for the transformation assay, we also demonstrated that oocytes repaired oxidative-type DNA base damage induced by X-rays. X-irradiation of a circular DNA stimulated its potential to recombine with a homologous linear partner. Recombination products were detectedmore » directly by Southern blot hybridization and as bacterial transformant clones expressing two antibiotic resistance markers originally carried separately on the two substrates. The increase in recombination was dependent on X-ray dose. There is some suggestion that lesions other than double-strand breaks contribute to the stimulation of oocyte-mediated homologous recombination. In summary, oocytes have considerable capacity to repair X-ray-induced damage, and some X-ray lesions stimulate homologous recombination in these cells.« less

Femtosecond response of polyatomic molecules to ultra-intense hard X-rays.

PubMed

Rudenko, A; Inhester, L; Hanasaki, K; Li, X; Robatjazi, S J; Erk, B; Boll, R; Toyota, K; Hao, Y; Vendrell, O; Bomme, C; Savelyev, E; Rudek, B; Foucar, L; Southworth, S H; Lehmann, C S; Kraessig, B; Marchenko, T; Simon, M; Ueda, K; Ferguson, K R; Bucher, M; Gorkhover, T; Carron, S; Alonso-Mori, R; Koglin, J E; Correa, J; Williams, G J; Boutet, S; Young, L; Bostedt, C; Son, S-K; Santra, R; Rolles, D

2017-06-01

X-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 10 20 watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities. Studies with intense X-ray pulses have shown that irradiated atoms reach a very high degree of ionization, owing to multiphoton absorption, which in a heteronuclear molecular system occurs predominantly locally on a heavy atom (provided that the absorption cross-section of the heavy atom is considerably larger than those of its neighbours) and is followed by efficient redistribution of the induced charge. In serial femtosecond crystallography of biological objects-an application of X-ray free-electron lasers that greatly enhances our ability to determine protein structure-the ionization of heavy atoms increases the local radiation damage that is seen in the diffraction patterns of these objects and has been suggested as a way of phasing the diffraction data. On the basis of experiments using either soft or less-intense hard X-rays, it is thought that the induced charge and associated radiation damage of atoms in polyatomic molecules can be inferred from the charge that is induced in an isolated atom under otherwise comparable irradiation conditions. Here we show that the femtosecond response of small polyatomic molecules that contain one heavy atom to ultra-intense (with intensities approaching 10 20 watts per square centimetre), hard (with photon energies of 8.3 kiloelectronvolts) X-ray pulses is qualitatively different: our experimental and modelling results establish that, under these conditions, the ionization of a molecule is considerably enhanced compared to that of an individual heavy atom with the same absorption cross-section. This enhancement is driven by ultrafast charge transfer within the molecule, which refills the core holes that are created in the heavy atom, providing further targets for inner-shell ionization and resulting in the emission of more than 50 electrons during the X-ray pulse. Our results demonstrate that efficient modelling of X-ray-driven processes in complex systems at ultrahigh intensities is feasible.

Femtosecond response of polyatomic molecules to ultra-intense hard X-rays

DOE PAGES

Rudenko, A.; Inhester, L.; Hanasaki, K.; ...

2017-05-31

We report x-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 10 20 watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities. Studies with intense X-ray pulses have shown that irradiated atoms reach a very high degree of ionization, owing to multiphoton absorption, which in a heteronuclear molecularmore » system occurs predominantly locally on a heavy atom (provided that the absorption cross-section of the heavy atom is considerably larger than those of its neighbours) and is followed by efficient redistribution of the induced charge. In serial femtosecond crystallography of biological objects—an application of X-ray free-electron lasers that greatly enhances our ability to determine protein structure—the ionization of heavy atoms increases the local radiation damage that is seen in the diffraction patterns of these objects and has been suggested as a way of phasing the diffraction data. On the basis of experiments using either soft or less-intense hard X-rays, it is thought that the induced charge and associated radiation damage of atoms in polyatomic molecules can be inferred from the charge that is induced in an isolated atom under otherwise comparable irradiation conditions. Here we show that the femtosecond response of small polyatomic molecules that contain one heavy atom to ultra-intense (with intensities approaching 10 20 watts per square centimetre), hard (with photon energies of 8.3 kiloelectronvolts) X-ray pulses is qualitatively different: our experimental and modelling results establish that, under these conditions, the ionization of a molecule is considerably enhanced compared to that of an individual heavy atom with the same absorption cross-section. This enhancement is driven by ultrafast charge transfer within the molecule, which refills the core holes that are created in the heavy atom, providing further targets for inner-shell ionization and resulting in the emission of more than 50 electrons during the X-ray pulse. Fnally, our results demonstrate that efficient modelling of X-ray-driven processes in complex systems at ultrahigh intensities is feasible.« less

Femtosecond response of polyatomic molecules to ultra-intense hard X-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudenko, A.; Inhester, L.; Hanasaki, K.

We report x-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 10 20 watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities. Studies with intense X-ray pulses have shown that irradiated atoms reach a very high degree of ionization, owing to multiphoton absorption, which in a heteronuclear molecularmore » system occurs predominantly locally on a heavy atom (provided that the absorption cross-section of the heavy atom is considerably larger than those of its neighbours) and is followed by efficient redistribution of the induced charge. In serial femtosecond crystallography of biological objects—an application of X-ray free-electron lasers that greatly enhances our ability to determine protein structure—the ionization of heavy atoms increases the local radiation damage that is seen in the diffraction patterns of these objects and has been suggested as a way of phasing the diffraction data. On the basis of experiments using either soft or less-intense hard X-rays, it is thought that the induced charge and associated radiation damage of atoms in polyatomic molecules can be inferred from the charge that is induced in an isolated atom under otherwise comparable irradiation conditions. Here we show that the femtosecond response of small polyatomic molecules that contain one heavy atom to ultra-intense (with intensities approaching 10 20 watts per square centimetre), hard (with photon energies of 8.3 kiloelectronvolts) X-ray pulses is qualitatively different: our experimental and modelling results establish that, under these conditions, the ionization of a molecule is considerably enhanced compared to that of an individual heavy atom with the same absorption cross-section. This enhancement is driven by ultrafast charge transfer within the molecule, which refills the core holes that are created in the heavy atom, providing further targets for inner-shell ionization and resulting in the emission of more than 50 electrons during the X-ray pulse. Fnally, our results demonstrate that efficient modelling of X-ray-driven processes in complex systems at ultrahigh intensities is feasible.« less

Tunable hole injection of solution-processed polymeric carbon nitride towards efficient organic light-emitting diode

NASA Astrophysics Data System (ADS)

Zhang, Xiaowen; Zheng, Qinghong; Tang, Zhenyu; Li, Wanshu; Zhang, Yan; Xu, Kai; Xue, Xiaogang; Xu, Jiwen; Wang, Hua; Wei, Bin

2018-02-01

Polymeric carbon nitride (CNxHy) has been facilely synthesized from dicyandiamide and functions as a solution-processed hole injection layer in organic light-emitting diodes (OLEDs). The measurements using X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and impedance spectroscopy elucidate that CNxHy exhibits superior film morphology and extra electric properties such as tailored work function and tunable hole injection. The luminous efficiency of CNxHy-based OLED is found to improve by 76.6% in comparison to the counterpart using favorite solution-processed poly(ethylene dioxythiophene):poly(styrene sulfonate) as the hole injection layer. Our results also pave a way for broadening carbon nitride applications in organic electronics using the solution process.

X-ray-induced changes in growth of Mozambique tilapia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jana, B.B.; Basu, M.

1995-01-01

Early fry (30 d postfertilization) and 7-8-week-old Mozambique tilapias (Tilapia mossambica) were exposed to X rays in dosages of 50, 100, 200, 300, 400 or 500 roentgens and reared in outdoor culture tanks between May 1981 and October 1988. Fish of either sex that were irradiated as fry grew faster than controls at all test X-ray doses. Among fish irradiated at 7-8 weeks, males grew significantly faster, but females grew significantly slower, than controls at all test doses. X-ray-induced changes in growth were dose-dependent: growth rates of fry (both sexes) and of juvenile males rose relative to those of controlsmore » with increased radiation dose. The growth increase per unit of radiation dose was higher for fry than for older juveniles. The length-weight regression was steeper for irradiated males than for controls. The average weights of F{sub 1} offspring of irradiated fish were greatly reduced as compared with controls, which suggests the transfer of the detrimental effects of X rays from irradiated parents to their offspring. 39 refs., 3 figs., 3 tabs.« less

Finding concealed high atomic numbered materials hidden in cargo containers using dual-energy high-energy x-rays from a linear accelerator with the unique signature from photofission

NASA Astrophysics Data System (ADS)

Clayton, James E.; Bjorkholm, Paul

2006-05-01

The Dual Energy X-ray technique employs two X-ray projection images of an object with X-ray energy spectra at a low X-ray energy and a high X-ray energy. The two energies are both high enough to penetrate all cargoes. The endpoint energies for low and high will be approximately 5-6 MeV and 8-9.5 MeV respectively. These energies are chosen such that pair production is the dominant energy loss mechanism for the high energy mode. By defining the ratio of the transmitted X-ray photon R = T high/T low it can be shown that there is a difference in the ratio that will permit the detection of materials that are significantly higher in atomic number than the low to mid atomic numbered elements that normally appear in the stream of commerce. This difference can be used to assist in the automatic detection of high atomic numbered materials. These materials might be a WMD or dirty bomb. When coupled with detectors that can observe the delayed signature of photon induced fission a confirmation of a WMD may be made. The use of the delayed photons and neutrons from Photofission can confirm the presence of Special Nuclear Materials (SNM). The energy required to induce fission in SNM by a photon is approximately 6 MeV with the maximum fission production rate from X-ray photons in the energy range of 12-15 MeV.

Proton-Induced X-Ray Emission Analysis of Crematorium Emissions

NASA Astrophysics Data System (ADS)

Ali, Salina; Nadareski, Benjamin; Safiq, Alexandrea; Smith, Jeremy; Yoskowitz, Josh; Labrake, Scott; Vineyard, Michael

2013-10-01

There has been considerable concern in recent years about possible mercury emissions from crematoria. We have performed a particle-induced X-ray emission (PIXE) analysis of atmospheric aerosol samples collected on the roof of the crematorium at Vale Cemetery in Schenectady, NY, to address this concern. The samples were collected with a nine-stage cascade impactor that separates the particulate matter according to particle size. The aerosol samples were bombarded with 2.2-MeV protons from the Union College 1.1-MV Pelletron Accelerator. The emitted X-rays were detected with a silicon drift detector and the X-ray energy spectra were analyzed using GUPIX software to determine the elemental concentrations. We measured significant concentrations of sulfur, phosphorus, potassium, calcium, and iron, but essentially no mercury. The lower limit of detection for mercury in this experiment was approximately 0.2 ng/m3. We will describe the experimental procedure, discuss the PIXE analysis, and present preliminary results.

Do Dental X-Rays Induce Genotoxicity and Cytotoxicity in Oral Mucosa Cells? A Critical Review.

PubMed

Angelieri, Fernanda; Yujra, Veronica Quispe; Oshima, Celina Tizuko Fujiyama; Ribeiro, Daniel Araki

2017-10-01

Dental X-rays are widely used in clinical practice, since the technique is an important approach for diagnosing diseases in dental and periodontal tissues. However, it is widely known that radiation is capable of causing damage to cellular systems, such as genotoxicity or cytotoxicity. Thus, the aim of this review was to present a critical analysis regarding the studies published on genotoxicity and cytotoxicity induced by dental X-rays in oral mucosa cells. Such studies have revealed that some oral cell types are more sensitive than others following exposure to dental X-rays. Certainly, this review will contribute to a better understanding of this matter as well as to highlighting perspectives for further studies. Ultimately, such data will promote better safety for both patients and dental professionals. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

An easy-to-implement filter for separating photo-excited signals from topography in scanning tunneling microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Kangkang; Rosenmann, Daniel; Holt, Martin

2013-06-15

In order to achieve elemental and chemical sensitivity in scanning tunneling microscopy (STM), synchrotron x-rays have been applied to excite core-level electrons during tunneling. The x-ray photo-excitations result in tip currents that are superimposed onto conventional tunneling currents. While carrying important physical information, the varying x-ray induced currents can destabilize the feedback loop causing it to be unable to maintain a constant tunneling current, sometimes even causing the tip to retract fully or crash. In this paper, we report on an easy-to-implement filter circuit that can separate the x-ray induced currents from conventional tunneling currents, thereby allowing simultaneous measurements ofmore » topography and chemical contrasts. The filter and the schematic presented here can also be applied to other variants of light-assisted STM such as laser STM.« less

Study of the physical properties of a mesogenic mixture showing induced smectic A(d) phase by refractive index, density and x-ray diffraction measurements.

PubMed

Roy, P D; Prasad, A; Das, M K

2009-02-18

The binary mixture of 4-n-pentyl phenyl 4-n'-hexyloxy benzoate (ME6O.5) and p-cyanophenyl trans-4-pentyl cyclohexane carboxylate (CPPCC) shows the presence of an induced smectic A(d) phase in a certain concentration range 0.030.33, whereas there is a discontinuity in these values for mixtures with x<0.33, consistent with the density and transition entropy measurements done on this system. The orientational order parameter, measured from x-ray diffraction studies, are somewhat smaller than those obtained from refractive index measurement in the induced smectic phase for all the mixtures. In the smectic phase, the OOP values initially increases with molar concentration up to x = 0.24 and then decreases showing a broad minima around x = 0.4. The variation of layer thickness in the induced smectic phase with composition has been explained by assuming the formation of homo- and heterodimers. We conclude that the possible packing of molecules in the induced smectic A(d) phase stabilizes the layers but increases the orientational free volume, consistent with the lower orientational order parameter.

Deep diode arrays for X-ray detection

NASA Technical Reports Server (NTRS)

Zemel, J. N.

1984-01-01

Temperature gradient zone melting process was used to form p-n junctions in bulk of high purity silicon wafers. These diodes were patterned to form arrays for X-ray spectrometers. The whole fabrication processes for these X-ray detectors are reviewed in detail. The p-n junctions were evaluated by (1) the dark diode I-V measurements, (2) the diode C sub I - V measurements, and (3) the MOS C-V measurements. The results showed that these junctions were linearly graded in charge distribution with low reverse bias leakage current flowing through them (few nA at -10 volts). The X-ray detection experiments showed that an FWHM of 500 eV was obtained from these diodes with a small bias of just -5 volts (for X-ray source Fe55). A theoretical model was proposed to explain the extra peaks found in the energy spectra and a very interesting point - cross talk effect was pointed out. This might be a solution to the problem of making really high resolution X-ray spectrometers.

X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser

DOE PAGES

Kroll, Thomas; Kern, Jan; Kubin, Markus; ...

2016-09-19

X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. But, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. We compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based onmore » self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. Lastly, we show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements.« less

Monte Carlo simulations for 20 MV X-ray spectrum reconstruction of a linear induction accelerator

NASA Astrophysics Data System (ADS)

Wang, Yi; Li, Qin; Jiang, Xiao-Guo

2012-09-01

To study the spectrum reconstruction of the 20 MV X-ray generated by the Dragon-I linear induction accelerator, the Monte Carlo method is applied to simulate the attenuations of the X-ray in the attenuators of different thicknesses and thus provide the transmission data. As is known, the spectrum estimation from transmission data is an ill-conditioned problem. The method based on iterative perturbations is employed to derive the X-ray spectra, where initial guesses are used to start the process. This algorithm takes into account not only the minimization of the differences between the measured and the calculated transmissions but also the smoothness feature of the spectrum function. In this work, various filter materials are put to use as the attenuator, and the condition for an accurate and robust solution of the X-ray spectrum calculation is demonstrated. The influences of the scattering photons within different intervals of emergence angle on the X-ray spectrum reconstruction are also analyzed.

X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser

PubMed Central

Kroll, Thomas; Kern, Jan; Kubin, Markus; Ratner, Daniel; Gul, Sheraz; Fuller, Franklin D.; Löchel, Heike; Krzywinski, Jacek; Lutman, Alberto; Ding, Yuantao; Dakovski, Georgi L.; Moeller, Stefan; Turner, Joshua J.; Alonso-Mori, Roberto; Nordlund, Dennis L.; Rehanek, Jens; Weniger, Christian; Firsov, Alexander; Brzhezinskaya, Maria; Chatterjee, Ruchira; Lassalle-Kaiser, Benedikt; Sierra, Raymond G.; Laksmono, Hartawan; Hill, Ethan; Borovik, Andrew; Erko, Alexei; Föhlisch, Alexander; Mitzner, Rolf; Yachandra, Vittal K.; Yano, Junko; Wernet, Philippe; Bergmann, Uwe

2016-01-01

X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. Here we compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based on self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. We show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements. PMID:27828320

Charged particle induced delayed X-rays (DEX) for the analysis of intermediate and heavy elements

NASA Astrophysics Data System (ADS)

Pillay, A. E.; Erasmus, C. S.; Andeweg, A. H.; Sellschop, J. P. F.; Annegarn, H. J.; Dunn, J.

1988-12-01

The emission of K X-rays from proton-rich and metastable radionuclides, following proton activation of the stable isotopes of the elements of interest, has not been widely used as a means of analysis. The thrust of this paper proposes a nuclear technique using delayed X-rays for the analysis of low concentrations of intermediate and heavy elements. The method is similar to the delayed gamma-ray technique. Proton bombardment induces mainly (p, n) reactions whereas the delayed X-rays originate largely from e --capture and isomeric transition. Samples of rare earth and platinum group elements (PGE), in the form of compacted powders, were irradiated with an 11 MeV proton beam and delayed X-rays detected with a 100 mm 2 Ge detector. Single element spectra for a range of rare earths and PGEs are presented. Analytical conditions are demonstrated for Pd in the range 0.1-5%. Spectra from actual geological samples of a PGE ore, preconcentrated by fire-assay, and monazite are presented. All six platinum group elements are visible and interference-free in a single spectrum, a marked advance on other nuclear techniques for these elements, including PIXE and neutron activation analysis (NAA).

The life science X-ray scattering beamline at NSLS-II

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiFabio, Jonathan; Yang, Lin; Chodankar, Shirish

We report the current development status of the High Brightness X-ray Scattering for Life Sciences (or Life Science X-ray Scattering, LiX) beamline at the NSLS-II facility of Brookhaven National Laboratory. This instrument will operate in the x-ray energy range of 2.1-18 keV, provide variable beam sizes from 1 micron to ~0.5 mm, and support user experiments in three scientific areas: (1) high-throughput solution scattering, in-line size exclusion chromatography and flow mixers-based time-resolved solution scattering of biological macro-molecules, (2) diffraction from single- and multi-layered lipid membranes, and (3) scattering-based scanning probe imaging of biological tissues. In order to satisfy the beammore » stability required for these experiments and to switch rapidly between different types of experiments, we have adopted a secondary source with refractive lenses for secondary focusing, a detector system consisting of three Pilatus detectors, and specialized experimental modules that can be quickly exchanged and each dedicated to a defined set of experiments. The construction of this beamline is on schedule for completion in September 2015. User experiments are expected to start in Spring 2016.« less

The life science X-ray scattering beamline at NSLS-II

DOE PAGES

DiFabio, Jonathan; Yang, Lin; Chodankar, Shirish; ...

2015-09-30

We report the current development status of the High Brightness X-ray Scattering for Life Sciences (or Life Science X-ray Scattering, LiX) beamline at the NSLS-II facility of Brookhaven National Laboratory. This instrument will operate in the x-ray energy range of 2.1-18 keV, provide variable beam sizes from 1 micron to ~0.5 mm, and support user experiments in three scientific areas: (1) high-throughput solution scattering, in-line size exclusion chromatography and flow mixers-based time-resolved solution scattering of biological macro-molecules, (2) diffraction from single- and multi-layered lipid membranes, and (3) scattering-based scanning probe imaging of biological tissues. In order to satisfy the beammore » stability required for these experiments and to switch rapidly between different types of experiments, we have adopted a secondary source with refractive lenses for secondary focusing, a detector system consisting of three Pilatus detectors, and specialized experimental modules that can be quickly exchanged and each dedicated to a defined set of experiments. The construction of this beamline is on schedule for completion in September 2015. User experiments are expected to start in Spring 2016.« less

The life science x-ray scattering beamline at NSLS-II

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiFabio, Jonathan; Chodankar, Shirish; Pjerov, Sal

We report the current development status of the High Brightness X-ray Scattering for Life Sciences (or Life Science X-ray Scattering, LiX) beamline at the NSLS-II facility of Brookhaven National Laboratory. This instrument will operate in the x-ray energy range of 2.1-18 keV, provide variable beam sizes from 1 micron to ∼0.5 mm, and support user experiments in three scientific areas: (1) high-throughput solution scattering, in-line size exclusion chromatography and flow mixers-based time-resolved solution scattering of biological macro-molecules, (2) diffraction from single- and multi-layered lipid membranes, and (3) scattering-based scanning probe imaging of biological tissues. In order to satisfy the beammore » stability required for these experiments and to switch rapidly between different types of experiments, we have adopted a secondary source with refractive lenses for secondary focusing, a detector system consisting of three Pilatus detectors, and specialized experimental modules that can be quickly exchanged and each dedicated to a defined set of experiments. The construction of this beamline is on schedule for completion in September 2015. User experiments are expected to start in Spring 2016.« less

Radiation-quality dependent cellular response in mutation induction in normal human cells.

PubMed

Suzuki, Masao; Tsuruoka, Chizuru; Uchihori, Yukio; Kitamura, Hisashi; Liu, Cui Hua

2009-09-01

We studied cellular responses in normal human fibroblasts induced with low-dose (rate) or low-fluence irradiations of different radiation types, such as gamma rays, neutrons and high linear energy transfer (LET) heavy ions. The cells were pretreated with low-dose (rate) or low-fluence irradiations (approximately 1 mGy/7-8 h) of 137Cs gamma rays, 241Am-Be neutrons, helium, carbon and iron ions before irradiations with an X-ray challenging dose (1.5 Gy). Helium (LET = 2.3 keV/microm), carbon (LET = 13.3 keV/microm) and iron (LET = 200 keV/microm) ions were produced by the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. No difference in cell-killing effect, measured by a colony forming assay, was observed among the pretreatment with different radiation types. In mutation induction, which was detected in the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus to measure 6-thioguanine resistant clones, there was no difference in mutation frequency induced by the X-ray challenging dose between unpretreated and gamma-ray pretreated cells. In the case of the pretreatment of heavy ions, X-ray-induced mutation was around 1.8 times higher in helium-ion pretreated and 4.0 times higher in carbon-ion pretreated cells than in unpretreated cells (X-ray challenging dose alone). However, the mutation frequency in cells pretreated with iron ions was the same level as either unpretreated or gamma-ray pretreated cells. In contrast, it was reduced at 0.15 times in cells pretreated with neutrons when compared to unpretreated cells. The results show that cellular responses caused by the influence of hprt mutation induced in cells pretreated with low-dose-rate or low-fluence irradiations of different radiation types were radiation-quality dependent manner.

Effect of Cyclic Thermal Process on Ultrafine Grain Formation in AISI 304L Austenitic Stainless Steel

NASA Astrophysics Data System (ADS)

Ravi Kumar, B.; Mahato, B.; Sharma, Sailaja; Sahu, J. K.

2009-12-01

As-received hot-rolled commercial grade AISI 304L austenitic stainless steel plates were solution treated at 1060 °C to achieve chemical homogeneity. Microstructural characterization of the solution-treated material revealed polygonal grains of about 85- μm size along with annealing twins. The solution-treated plates were heavily cold rolled to about 90 pct of reduction in thickness. Cold-rolled specimens were then subjected to thermal cycles at various temperatures between 750 °C and 925 °C. X-ray diffraction showed about 24.2 pct of strain-induced martensite formation due to cold rolling of austenitic stainless steel. Strain-induced martensite formed during cold rolling reverted to austenite by the cyclic thermal process. The microstructural study by transmission electron microscope of the material after the cyclic thermal process showed formation of nanostructure or ultrafine grain austenite. The tensile testing of the ultrafine-grained austenitic stainless steel showed a yield strength 4 to 6 times higher in comparison to its coarse-grained counterpart. However, it demonstrated very poor ductility due to inadequate strain hardenability. The poor strain hardenability was correlated with the formation of strain-induced martensite in this steel grade.

Direct identification and analysis of heavy metals in solution (Hg, Cu, Pb, Zn, Ni) by use of in situ electrochemical X-ray fluorescence.

PubMed

O'Neil, Glen D; Newton, Mark E; Macpherson, Julie V

2015-01-01

The development and application of a new methodology, in situ electrochemical X-ray fluorescence (EC-XRF), is described that enables direct identification and quantification of heavy metals in solution. A freestanding film of boron-doped diamond serves as both an X-ray window and the electrode material. The electrode is biased at a suitable driving potential to electroplate metals from solution onto the electrode surface. Simultaneously, X-rays that pass through the back side of the electrode interrogate the time-dependent electrodeposition process by virtue of the XRF signals, which are unique to each metal. In this way it is possible to unambiguously identify which metals are in solution and relate the XRF signal intensity to a concentration of metal species in solution. To increase detection sensitivity and reduce detection times, solution is flown over the electrode surface by use of a wall-jet configuration. Initial studies focused on the in situ detection of Pb(2+), where concentration detection limits of 99 nM were established in this proof-of-concept study (although significantly lower values are anticipated with system refinement). This is more than 3 orders of magnitude lower than that achievable by XRF alone in a flowing solution (0.68 mM). In situ EC-XRF measurements were also carried out on a multimetal solution containing Hg(2+), Pb(2+), Cu(2+), Ni(2+), Zn(2+), and Fe(3+) (all at 10 μM concentration). Identification of five of these metals was possible in one simple measurement. In contrast, while anodic stripping voltammetry (ASV) also revealed five peaks, peak identification was not straightforward, requiring further experiments and prior knowledge of the metals in solution. Time-dependent EC-XRF nucleation data for the five metals, recorded simultaneously, demonstrated similar deposition rates. Studies are now underway to lower detection limits and provide a quantitative understanding of EC-XRF responses in real, multimetal solutions. Finally, the production of custom-designed portable in situ EC-XRF instrumentation will make heavy metal analysis at the source a very realistic possibility.

Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography

NASA Astrophysics Data System (ADS)

Walton, Lucy A.; Bradley, Robert S.; Withers, Philip J.; Newton, Victoria L.; Watson, Rachel E. B.; Austin, Clare; Sherratt, Michael J.

2015-05-01

Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons.

Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography

PubMed Central

Walton, Lucy A.; Bradley, Robert S.; Withers, Philip J.; Newton, Victoria L.; Watson, Rachel E. B.; Austin, Clare; Sherratt, Michael J.

2015-01-01

Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons. PMID:25975937

Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemke, Henrik T.; Kjær, Kasper S.; Hartsock, Robert

The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born–Oppenheimer approximation, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy)3]2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersionmore » of the wave packet along the reaction coordinate reveals details of intramolecular vibronic coupling before a slower vibrational energy dissipation to the solution environment. These findings illustrate how modern time-resolved X-ray absorption spectroscopy can provide key information to unravel dynamic details of photo-functional molecules.« less

Coating Thin Mirror Segments for Lightweight X-ray Optics

NASA Technical Reports Server (NTRS)

Chan, Kai-Wing; Sharpe, Marton V.; Zhang, William; Kolosc, Linette; Hong, Melinda; McClelland, Ryan; Hohl, Bruce R.; Saha, Timo; Mazzarellam, James

2013-01-01

Next generations lightweight, high resolution, high throughput optics for x-ray astronomy requires integration of very thin mirror segments into a lightweight telescope housing without distortion. Thin glass substrates with linear dimension of 200 mm and thickness as small as 0.4 mm can now be fabricated to a precision of a few arc-seconds for grazing incidence optics. Subsequent implementation requires a distortion-free deposition of metals such as iridium or platinum. These depositions, however, generally have high coating stresses that cause mirror distortion. In this paper, we discuss the coating stress on these thin glass mirrors and the effort to eliminate their induced distortion. It is shown that balancing the coating distortion either by coating films with tensile and compressive stresses, or on both sides of the mirrors is not sufficient. Heating the mirror in a moderately high temperature turns out to relax the coated films reasonably well to a precision of about a second of arc and therefore provide a practical solution to the coating problem.

Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

DOE PAGES

Lemke, Henrik T.; Kjær, Kasper S.; Hartsock, Robert; ...

2017-05-24

The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born–Oppenheimer approximation, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy)3]2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersionmore » of the wave packet along the reaction coordinate reveals details of intramolecular vibronic coupling before a slower vibrational energy dissipation to the solution environment. These findings illustrate how modern time-resolved X-ray absorption spectroscopy can provide key information to unravel dynamic details of photo-functional molecules.« less

Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

NASA Astrophysics Data System (ADS)

Lemke, Henrik T.; Kjær, Kasper S.; Hartsock, Robert; van Driel, Tim B.; Chollet, Matthieu; Glownia, James M.; Song, Sanghoon; Zhu, Diling; Pace, Elisabetta; Matar, Samir F.; Nielsen, Martin M.; Benfatto, Maurizio; Gaffney, Kelly J.; Collet, Eric; Cammarata, Marco

2017-05-01

The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born-Oppenheimer approximation, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy)3]2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersion of the wave packet along the reaction coordinate reveals details of intramolecular vibronic coupling before a slower vibrational energy dissipation to the solution environment. These findings illustrate how modern time-resolved X-ray absorption spectroscopy can provide key information to unravel dynamic details of photo-functional molecules.

Early nucleation events in the polymerization of actin, probed by time-resolved small-angle x-ray scattering

PubMed Central

Oda, Toshiro; Aihara, Tomoki; Wakabayashi, Katsuzo

2016-01-01

Nucleators generating new F-actin filaments play important roles in cell activities. Detailed information concerning the events involved in nucleation of actin alone in vitro is fundamental to understanding these processes, but such information has been hard to come by. We addressed the early process of salt-induced polymerization of actin using the time-resolved synchrotron small-angle X-ray scattering (SAXS). Actin molecules in low salt solution maintain a monomeric state by an electrostatic repulsive force between molecules. On mixing with salts, the repulsive force was rapidly screened, causing an immediate formation of many of non-polymerizable dimers. SAXS kinetic analysis revealed that tetramerization gives the highest energetic barrier to further polymerization, and the major nucleation is the formation of helical tetramers. Filaments start to grow rapidly with the formation of pentamers. These findings suggest an acceleration mechanism of actin assembly by a variety of nucleators in cells. PMID:27775032

Attosecond time-energy structure of X-ray free-electron laser pulses

NASA Astrophysics Data System (ADS)

Hartmann, N.; Hartmann, G.; Heider, R.; Wagner, M. S.; Ilchen, M.; Buck, J.; Lindahl, A. O.; Benko, C.; Grünert, J.; Krzywinski, J.; Liu, J.; Lutman, A. A.; Marinelli, A.; Maxwell, T.; Miahnahri, A. A.; Moeller, S. P.; Planas, M.; Robinson, J.; Kazansky, A. K.; Kabachnik, N. M.; Viefhaus, J.; Feurer, T.; Kienberger, R.; Coffee, R. N.; Helml, W.

2018-04-01

The time-energy information of ultrashort X-ray free-electron laser pulses generated by the Linac Coherent Light Source is measured with attosecond resolution via angular streaking of neon 1s photoelectrons. The X-ray pulses promote electrons from the neon core level into an ionization continuum, where they are dressed with the electric field of a circularly polarized infrared laser. This induces characteristic modulations of the resulting photoelectron energy and angular distribution. From these modulations we recover the single-shot attosecond intensity structure and chirp of arbitrary X-ray pulses based on self-amplified spontaneous emission, which have eluded direct measurement so far. We characterize individual attosecond pulses, including their instantaneous frequency, and identify double pulses with well-defined delays and spectral properties, thus paving the way for X-ray pump/X-ray probe attosecond free-electron laser science.

X-Raying the Beating Heart of a Newborn Star: Rotational Modulation of High-Energy Radiation from V1647 Ori

NASA Technical Reports Server (NTRS)

Hamaguchi, Kenji; Grosso, Nicolas; Kastner, Joel H.; Weintraub, David A.; Richmond, Michael; Petre, Robert; Teets, William K.; Principe, David

2012-01-01

We report a periodicity of approx.1 day in the highly elevated X-ray emission from the protostar V1647 Ori during its two recent multiple-year outbursts of mass accretion. This periodicity is indicative of protostellar rotation at near-breakup speed. Modeling of the phased X-ray light curve indicates the high-temperature ( 50 MK), X-ray-emitting plasma, which is most likely heated by accretion-induced magnetic reconnection, resides in dense ( 5 1010 cm.3), pancake-shaped magnetic footprints where the accretion stream feeds the newborn star. The sustained X-ray periodicity of V1647 Ori demonstrates that such protostellar magnetospheric accretion configurations can be stable over timescales of years. Subject headings: stars: formation stars: individual (V1647 Ori) stars: pre-main sequence X-rays: stars

Light-induced radical formation and isomerization of an aromatic thiol in solution followed by time-resolved x-ray absorption spectroscopy at the sulfur K-edge

DOE PAGES

Ochmann, Miguel; von Ahnen, Inga; Cordones, Amy A.; ...

2017-02-20

Here, we applied time-resolved sulfur-1s absorption spectroscopy to a model aromatic thiol system as a promising method for tracking chemical reactions in solution. Sulfur-1s absorption spectroscopy allows tracking multiple sulfur species with a time resolution of ~70 ps at synchrotron radiation facilities. Experimental transient spectra combined with high-level electronic structure theory allow identification of a radical and two thione isomers, which are generated upon illumination with 267 nm radiation. Moreover, the regioselectivity of the thione isomerization is explained by the resulting radical frontier orbitals. This work demonstrates the usefulness and potential of time-resolved sulfur-1s absorption spectroscopy for tracking multiple chemicalmore » reaction pathways and transient products of sulfur-containing molecules in solution.« less

Light-induced radical formation and isomerization of an aromatic thiol in solution followed by time-resolved x-ray absorption spectroscopy at the sulfur K-edge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ochmann, Miguel; von Ahnen, Inga; Cordones, Amy A.

Here, we applied time-resolved sulfur-1s absorption spectroscopy to a model aromatic thiol system as a promising method for tracking chemical reactions in solution. Sulfur-1s absorption spectroscopy allows tracking multiple sulfur species with a time resolution of ~70 ps at synchrotron radiation facilities. Experimental transient spectra combined with high-level electronic structure theory allow identification of a radical and two thione isomers, which are generated upon illumination with 267 nm radiation. Moreover, the regioselectivity of the thione isomerization is explained by the resulting radical frontier orbitals. This work demonstrates the usefulness and potential of time-resolved sulfur-1s absorption spectroscopy for tracking multiple chemicalmore » reaction pathways and transient products of sulfur-containing molecules in solution.« less

X-ray photoelectron spectroscopic study of the oxide film on an aluminum-tin alloy in 3.5% sodium chloride solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Venugopal, A.; Selvam, P.; Raja, V.S.

1997-10-01

Oxide films on Al and an Al-Sn alloy were analyzed by x-ray photoelectron spectroscopy (XPS) after immersion in 3.5% sodium chloride (NaCl) solution. Results showed Sn exhibited both Sn{sup 2+} and Sn{sup 4+} oxidation stats in the oxide film. It was proposed that incorporation of these cations in the film would result in generation of more anionic and cationic vacancies in aluminum oxide (Al{sub 2}O{sub 3}), leading to active dissolution of Al.

Specimen preparation for x-ray fluorescence analysis of solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eksperiandova, L.P.; Spolnik, Z.M.; Blank, A.B.

1995-12-31

Specimens for x-ray fluorescence analysis (XRFA) were prepared by adding dry gelatine (10%) to the analysis solution, homogenizing the mixture and cooling for 20 minutes. Thus, a compact resilient mass could be formed with the required shape and size; the roughness of the surface was determined by the roughness of the surface on which the specimen was formed, much the same as highly polished. Various calibration methods can be applied in the XRFA of a variety of materials if such specimens are used. 12 refs., 1 fig., 2 tabs.

Corrosion and degradation of a polyurethane/Co-Ni-Cr-Mo pacemaker lead

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sung, P.; Fraker, A.C.

1987-12-01

An investigation to study changes in the metal surfaces and the polyurethane insulation of heart pacemaker leads under controlled in vitro conditions was conducted. A polyurethane (Pellethane 2363-80A)/Co-Ni-Cr-Mo (MP35N) wire lead was exposed in Hanks' physiological saline solution for 14 months and then analyzed using scanning electron microscopy, x-ray energy dispersive analysis, and small angle x-ray scattering. Results showed that some leakage of solution into the lead had occurred and changes were present on both the metal and the polyurethane surfaces.

Relaxation of the structure of simple metal ion complexes in aqueous solutions at up to supercritical conditions

USGS Publications Warehouse

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

2003-01-01

Recently x-ray absorption fine structure (XAFS) studies of various ions in aqueous solutions showed a variation of cation-ligand bond lengths, often coupled with other structure changes, with increasing temperatures. Thus, the variations of the structure of several metal ion complexes with temperature based on observations from the X-ray absorption fine structure (XAFS) studies in the hope that it will stimulate the development of either first- principles theory or molecular dynamics simulations that might adequately describes these results are discussed.

C-1s NEXAFS spectroscopy reveals chemical fractionation of humic acid by cation-induced coagulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christl,I.; Kretzschmar, R.

2007-01-01

The influence of cation-induced coagulation on the chemical composition of dissolved and coagulated fractions of humic acid was investigated in batch coagulation experiments for additions of aluminum at pH 4 and 5, iron at pH 4, and calcium and lead at pH 6. The partitioning of organic carbon and metals was determined by analyzing total organic carbon and total metal contents of the dissolved phase. Both the dissolved and the coagulated humic acid fractions were characterized using synchrotron scanning transmission X-ray microscopy (STXM) and C-1s near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Intensities of {pi}* transitions of carboxyl carbon andmore » {sigma}* transitions of alkyl, O-alkyl, and carboxyl carbon decreased with increasing metal concentration for the dissolved humic acid fractions. This decrease was accompanied by an increase of the respective intensities in the coagulated fraction as shown for lead. Intensities of aromatic and phenolic carbon were affected to a larger extent only by aluminum and iron additions. The changes observed in the C-1s NEXAFS spectra coincided with an increasing removal of organic carbon from the dissolved phase with increasing total metal concentrations. We conclude that humic acid was chemically fractionated by cation-induced coagulation, which preferentially removed functional groups involved in metal-cation binding from solution.« less

Influence of caffeine on X-ray-induced killing and mutation in V79 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattacharjee, S.B.; Bhattacharyya, N.; Chatterjee, S.

1987-02-01

Effects produced by caffeine on X-irradiated Chinese hamster V79 cells depended on the growth conditions of the cells. For exponentially growing cells, nontoxic concentrations of caffeine decreased the shoulder width from the survival curve, but the slope remained unchanged. The yield of mutants under the same conditions also remained unaffected. In case of density-inhibited cells, delaying trypsinization for 24 h after X irradiation increased the survival and decreased the yield of mutants. The presence of caffeine during this incubation period inhibited such recovery and significantly increased the yield of X-ray-induced mutants.

Characterization of ion-induced radiation effects in nuclear materials using synchrotron x-ray techniques

DOE PAGES

Lang, Maik; Tracy, Cameron L.; Palomares, Raul I.; ...

2015-05-01

Recent efforts to characterize the nanoscale structural and chemical modifications induced by energetic ion irradiation in nuclear materials have greatly benefited from the application of synchrotron-based x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) techniques. Key to the study of actinide-bearing materials has been the use of small sample volumes, which are particularly advantageous, as the small quantities minimize the level of radiation exposure at the ion-beam and synchrotron user facility. This approach utilizes energetic heavy ions (energy range: 100 MeV–3 GeV) that pass completely through the sample thickness and deposit an almost constant energy per unit length along theirmore » trajectory. High energy x-rays (25–65 keV) from intense synchrotron light sources are then used in transmission geometry to analyze ion-induced structural and chemical modifications throughout the ion tracks. We describe in detail the experimental approach for utilizing synchrotron radiation (SR) to study the radiation response of a range of nuclear materials (e.g., ThO 2 and Gd 2Ti xZr 2–xO 7). Also addressed is the use of high-pressure techniques, such as the heatable diamond anvil cell, as a new means to expose irradiated materials to well-controlled high-temperature (up to 1000 °C) and/or high-pressure (up to 50 GPa) conditions. Furthermore, this is particularly useful for characterizing the annealing kinetics of irradiation-induced material modifications.« less

DNA conformations in mismatch repair probed in solution by X-ray scattering from gold nanocrystals

PubMed Central

Hura, Greg L.; Tsai, Chi-Lin; Claridge, Shelley A.; Mendillo, Marc L.; Smith, Jessica M.; Williams, Gareth J.; Mastroianni, Alexander J.; Alivisatos, A. Paul; Putnam, Christopher D.; Kolodner, Richard D.; Tainer, John A.

2013-01-01

DNA metabolism and processing frequently require transient or metastable DNA conformations that are biologically important but challenging to characterize. We use gold nanocrystal labels combined with small angle X-ray scattering to develop, test, and apply a method to follow DNA conformations acting in the Escherichia coli mismatch repair (MMR) system in solution. We developed a neutral PEG linker that allowed gold-labeled DNAs to be flash-cooled and stored without degradation in sample quality. The 1,000-fold increased gold nanocrystal scattering vs. DNA enabled investigations at much lower concentrations than otherwise possible to avoid concentration-dependent tetramerization of the MMR initiation enzyme MutS. We analyzed the correlation scattering functions for the nanocrystals to provide higher resolution interparticle distributions not convoluted by the intraparticle distribution. We determined that mispair-containing DNAs were bent more by MutS than complementary sequence DNA (csDNA), did not promote tetramer formation, and allowed MutS conversion to a sliding clamp conformation that eliminated the DNA bends. Addition of second protein responder MutL did not stabilize the MutS-bent forms of DNA. Thus, DNA distortion is only involved at the earliest mispair recognition steps of MMR: MutL does not trap bent DNA conformations, suggesting migrating MutL or MutS/MutL complexes as a conserved feature of MMR. The results promote a mechanism of mismatch DNA bending followed by straightening in initial MutS and MutL responses in MMR. We demonstrate that small angle X-ray scattering with gold labels is an enabling method to examine protein-induced DNA distortions key to the DNA repair, replication, transcription, and packaging. PMID:24101514

Manganese-calcium intermixing facilitates heteroepitaxial growth at the (1014) calcite-water interface

DOE PAGES

Xu, Man; Riechers, Shawn L.; Ilton, Eugene S.; ...

2017-09-05

For this research, in situ atomic force microscopy (AFM) measurements were performed to probe surface precipitates that formed on the (10more » $$\\bar{1}$$4) surface of calcite (CaCO 3) single crystals following reaction with Mn2 +-bearing aqueous solutions. Three-dimensional epitaxial islands were observed to precipitate and grow on the surfaces. In situ time-sequenced measurements demonstrated that the growth rates were commensurate with those obtained for epitaxial islands formed on calcite crystals reacted with Cd2 +-bearing aqueous solutions of the same range in supersaturation with respect to the pure metal carbonate phase. This finding was unexpected as rhodochrosite (MnCO 3) and calcite display a 10% lattice mismatch, based on the area of their (10$$\\bar{1}$$4) surface unit cells, whereas the lattice mismatch is only 4% for otavite (CdCO 3) and calcite. Coatings of varying thicknesses were therefore synthesized by reacting calcite single crystals in calcite-equilibrated aqueous solutions with up to 250 μM MnCl 2. Ex situ X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectivity (XRR), and AFM measurements of the reacted crystals demonstrated the formation of an epitaxial (Mn,Ca)CO 3 solid solution. The epitaxial solid solution had a spatially complex composition, whereby the first few nanometers were rich in Ca and the Mn content increased with distance from the original calcite surface, culminating in a topmost region of almost pure MnCO 3 for the thickest coatings. The effective lattice mismatch was therefore much smaller than the nominal mismatch thus explaining the measured growth rates. Lastly, these findings highlight the strong influence played by the substrate on the composition of surface precipitates in aqueous conditions.« less

Explosives detection using photoneutrons produced by X-rays

NASA Astrophysics Data System (ADS)

Yang, Yigang; Li, Yuanjing; Wang, Haidong; Li, Tiezhu; Wu, Bin

2007-08-01

The detection of explosives has become a critical issue after recent terrorist attacks. This paper describes research on explosives detection using photoneutrons from a photoneutron convertor that consists of 20 kg heavy water in an aluminum container whose shape was optimized to most effectively convert X-rays to photoneutrons. The X-rays were produced by a 9 MeV electron accelerator with an average electron current of 100 μA, resulted in a photoneutron yield of >10 11 n/s. Monte-Carlo simulations show that the radiation field is composed of X-ray pulses, fast neutron pulses and thermal neutrons. Both the X-ray and fast neutron pulses are 5 μs wide with a 300 Hz repetition frequency. The thermal neutron flux, which is higher than 10 4 n/cm 2/s, is essentially time invariant. A time shielding circuit was developed for the spectrometry system to halt the sampling process during the intense X-ray pulses. Paraffin, boron carbide and lead were used to protect the detector from interference from the X-rays, fast neutrons, thermal neutrons and background γ-rays coming from the system materials induced by photoneutrons. 5″×5″ NaI (Tl) scintillators were chosen as the detectors to detect the photoneutrons induced γ-rays from the inspected explosive simulant. Nitrogen (6.01 cps) 10.828 MeV γ-rays were detected with one detector from a 50 kg carbamide block placed 60 cm in front of the detector. A collimator was used to reduce the number of background 10.828 MeV γ-rays coming from the nitrogen in the air to improve the signal to background ratio from 0.136 to 1.81. A detector array of seven 5″×5″ NaI (Tl) detectors was used to measure the 2-D distributions of N and H in the sample. The combination of photoneutron analysis and X-ray imaging shows promise for enhancing explosives detection capabilities.

Study of mass flow distribution and chemical composition of comets from solar induced X-ray fluorescence

NASA Technical Reports Server (NTRS)

Gorenstein, P.

1979-01-01

The expected performance of an X-ray detector as an instrument aboard a mission to a comet was evaluated. The functions of the detector are both nondispersive analysis of chemical composition and measurement of mass flow from the comet nucleus. Measurements are to be carried out at a distance from the comet. The approach distances considered are of the order of 1000 km and 100 km. A new type of X-ray detector, a proportional scintillation detector, is considered as an X-ray counter for nondispersive elemental analysis.

Local x-ray structure analysis of optically manipulated biological micro-objects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cojoc, Dan; Ferrari, Enrico; Santucci, Silvia C.

2010-12-13

X-ray diffraction using micro- and nanofocused beams is well suited for nanostructure analysis at different sites of a biological micro-object. To conduct in vitro studies without mechanical contact, we developed object manipulation by optical tweezers in a microfluidic cell. Here we report x-ray microdiffraction analysis of a micro-object optically trapped in three dimensions. We revealed the nanostructure of a single starch granule at different points and investigated local radiation damage induced by repeated x-ray exposures at the same position, demonstrating high stability and full control of the granule orientation by multiple optical traps.

Photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite films in an aerated 0.5 M NaCl solution

NASA Astrophysics Data System (ADS)

Boonserm, Aleena; Kruehong, Chaiyaput; Seithtanabutara, Varinrumpai; Artnaseaw, Apichart; Kwakhong, Panomkorn

2017-10-01

This research aimed to investigate the photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite films using electrochemical measurements in an aerated 0.5 M NaCl solution under white light illumination. The CdS/TiO2 nanocomposite films were prepared by chemical bath deposition technique in a solution of cadmium and sulfide ions. The high resolution images of CdS/TiO2 nanocomposite films were provided by field emission scanning electron microscope. Theirs chemical identification and quantitative compositional information, crystallinity and actual chemical compounds formed were determined by energy dispersive spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The results indicated that the photoelectrochemical activity of the films depended strongly on CdS content. From the preparation of CdS/TiO2 nanocomposite films by 5, 10 and 15 dipping cycles in the chemical solutions, the best photoelectrochemical response was revealed by the 10 dipping cycles-prepared film. Galvanic couple testing demonstrated that the photoelectrochemical response of the film decreased continuously compared to that of anodized nanoporous TiO2 substrate which described by photocorrosion of CdS nanoparticles. In addition, chloride-ion attack also induced pitting corrosion leading to fluctuation and deterioration of photoelectrochemical response. CdO2 and Cd(OH)2 depositions were found as the main photocorrosion products on collapsed nanostructured-surface. The relevance between photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite film was discussed in detail.

In situ spectroscopic and solution analyses of the reductive dissolution of Mn02 by Fe(II)

USGS Publications Warehouse

Villinski, John E.; O'Day, Peggy A.; Corley, Timothy L.; Conklin, Martha H.

2001-01-01

The reductive dissolution of MnO2 by Fe(II) under conditions simulating acid mine drainage (pH 3, 100 mM SO42-) was investigated by utilizing a flow-through reaction cell and synchrotron X-ray absorption spectroscopy. This configuration allows collection of in situ, real-time X-ray absorption near-edge structure (XANES) spectra and bulk solution samples. Analysis of the solution chemistry suggests that the reaction mechanism changed (decreased reaction rate) as MnO2 was reduced and Fe(III) precipitated, primarily as ferrihydrite. Simultaneously, we observed an additional phase, with the local structure of jacobsite (MnFe2O4), in the Mn XANES spectra of reactants and products. The X-ray absorbance of this intermediate phase increased during the experiment, implying an increase in concentration. The presence of this phase, which probably formed as a surface coating, helps to explain the reduced rate of dissolution of manganese(IV) oxide. In natural environments affected by acid mine drainage, the formation of complex intermediate solid phases on mineral surfaces undergoing reductive dissolution may likewise influence the rate of release of metals to solution.

Micropore x-ray optics using anisotropic wet etching of (110) silicon wafers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ezoe, Yuichiro; Koshiishi, Masaki; Mita, Makoto

2006-12-10

To develop x-ray mirrors for micropore optics, smooth silicon (111)sidewalls obtained after anisotropic wet etching of a silicon (110) wafer were studied. A sample device with 19 {mu}m wide (111) sidewalls was fabricated using a 220 {mu}m thick silicon (110) wafer and potassium hydroxide solution. For what we believe to be the first time,x-ray reflection on the (111) sidewalls was detected in the angular response measurement. Compared to ray-tracing simulations, the surface roughness of the sidewalls was estimated to be 3-5 nm, which is consistent with the atomic force microscope and the surface profiler measurements.

Micropore x-ray optics using anisotropic wet etching of (110) silicon wafers.

PubMed

Ezoe, Yuichiro; Koshiishi, Masaki; Mita, Makoto; Mitsuda, Kazuhisa; Hoshino, Akio; Ishisaki, Yoshitaka; Yang, Zhen; Takano, Takayuki; Maeda, Ryutaro

2006-12-10

To develop x-ray mirrors for micropore optics, smooth silicon (111) sidewalls obtained after anisotropic wet etching of a silicon (110) wafer were studied. A sample device with 19 microm wide (111) sidewalls was fabricated using a 220 microm thick silicon (110) wafer and potassium hydroxide solution. For what we believe to be the first time, x-ray reflection on the (111) sidewalls was detected in the angular response measurement. Compared to ray-tracing simulations, the surface roughness of the sidewalls was estimated to be 3-5 nm, which is consistent with the atomic force microscope and the surface profiler measurements.

Stress-specific p38 MAPK activation is sufficient to drive EGFR endocytosis but not its nuclear translocation.

PubMed

Tomas, Alejandra; Jones, Sylwia; Vaughan, Simon O; Hochhauser, Daniel; Futter, Clare E

2017-08-01

EGF receptor (EGFR) endocytosis is induced by stress in a manner dependent on the p38 MAPK family. Ligand and stresses such as X-rays, reportedly promote nuclear trafficking of endocytosed EGFR for regulation of gene transcription and DNA repair. We fail to detect EGFR endocytosis or nuclear transport following X-ray treatment of HeLa or head and neck cancer cells, despite extensive DNA damage induction. Apparent nuclear staining with EGFR extracellular domain antibody remained present despite reduced/absent EGFR expression, and so did not represent nuclear EGFR. UVB and UVC, but not X-ray or UVA, treatment induced p38 activation and EGFR endocytosis, although all of these stresses induced DNA damage, indicating that DNA damage alone is not sufficient to induce EGFR endocytosis. Increased reactive oxygen species (ROS) levels following UVB treatment, compared to that seen with X-rays, do not alone explain differences in p38 activation. UVB, like UVC, induced EGFR accumulation predominantly in perinuclear endosomes, rather than in the nucleus. Our morphological techniques identifying major changes in receptor distribution do not exclude the possibility that small but biologically relevant amounts of EGFR enter the nucleus. This study highlights the importance and limitations of morphological analyses of receptor distribution in understanding signaling outcome. © 2017. Published by The Company of Biologists Ltd.

The Importance of Particle Induced X-Ray Emission (PIXE) Analysis and Imaging to the Search for Life on the Ocean Worlds

NASA Technical Reports Server (NTRS)

Blake, D. F.; Sarrazin, P.; Thompson, Kathleen

2017-01-01

The MapX imaging X-ray spectrometer is described and Monte Carlo modeling is used to show the efficacy of 244-Cm radioisotope sources in detecting and quantifying the biogenic elements in ices on Ocean Worlds such as Europa.

Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer

DOE PAGES

Dell'Angela, M.; Anniyev, T.; Beye, M.; ...

2015-03-01

Vacuum space charge-induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse.

Spin state switching of metal complexes by visible light or hard X-rays.

PubMed

Unruh, Daniel; Homenya, Patrick; Kumar, Manish; Sindelar, Ralf; Garcia, Yann; Renz, Franz

2016-09-28

Electromagnetic stimuli of spin crossover compounds restricted to UV-vis light irradiation for many years could be recently extended to X-ray excitation. This review covers a large variety of light-induced effects, as well as recent analogues stimulated by X-ray irradiation which have not yet been reviewed. The focus is also on multistable multinuclear spin crossover compounds which are the subject of lively discussions within the spin crossover community. Their spin transition often occurs incompletely and with different switching mechanisms. In this review, we recall a predicted sequential switching induced thermally as well as a concerted stimulation mechanism by light irradiation for these interesting multifunctional materials.

Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer.

PubMed

Dell'Angela, M; Anniyev, T; Beye, M; Coffee, R; Föhlisch, A; Gladh, J; Kaya, S; Katayama, T; Krupin, O; Nilsson, A; Nordlund, D; Schlotter, W F; Sellberg, J A; Sorgenfrei, F; Turner, J J; Öström, H; Ogasawara, H; Wolf, M; Wurth, W

2015-03-01

Vacuum space charge induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse.

A comparative study on radioprotective effect of N-acetylcysteine against 12C6+ ion versus X-rays

NASA Astrophysics Data System (ADS)

Liu, Yang; Zhang, Hong; Zhang, Luwei

Purpose: The aim of this study was to evaluate the different protective efficacy of N-acetylcysteine (NAC, 200 mg/kg dose) against 12C6+ ion (4 Gy) and X-rays (4 Gy) - induced damage in vivo model. Method: Kung-Ming female mice were divided into six groups, each composed of twelve animals: control group, two irradiation groups, and two NAC-treated groups, as well as NAC alone-treated group. An acute study was carried out to determine alterations in the oxidative stress (malondialdehyde level) using with colorimetric method and cell apoptosis measuring by flow cytometry as well as DNA-single strand break analyzing by comet assay at 2h after irradiation in mouse liver. Results: Compared with respective irradiation group, NAC can significantly ameliorate injury induced by two types of ionizing irradiation, which marked by the decrease of malondialdehyde level, and the reduction of apoptosis cells percentage and DNA damage. But the greater efficacy of NAC was prominently observed to inhibit the damage induced by X-rays, suggesting that NAC-mediated protective effect is more advisable to X-rays than 12C6+ ion irradiation. Moreover, NAC treatment alone did not result in any damage as compared to the control group. Conclusion: NAC may merit development as a potential radioprotective agent. Furthermore, NAC might exert its best effort to respond X rays-caused damage.

Feasibility of Valence-to-Core X-ray Emission Spectroscopy for Tracking Transient Species

DOE PAGES

March, Anne Marie; Assefa, Tadesse A.; Bressler, Christian; ...

2015-02-09

X-ray spectroscopies, when combined in laser-pump, X-ray-probe measurement schemes, can be powerful tools for tracking the electronic and geometric structural changes that occur during the course of a photoinitiated chemical reaction. X-ray absorption spectroscopy (XAS) is considered an established technique for such measurements, and X-ray emission spectroscopy (XES) of the strongest core-to-core emission lines (Kα and Kβ) is now being utilized. Flux demanding valence-to-core XES promises to be an important addition to the time-resolved spectroscopic toolkit. Here In this paper we present measurements and density functional theory calculations on laser-excited, solution-phase ferrocyanide that demonstrate the feasibility of valence-to-core XES formore » time-resolved experiments. Lastly, we discuss technical improvements that will make valence-to-core XES a practical pump–probe technique.« less

Dynamical effects in Bragg coherent x-ray diffraction imaging of finite crystals

NASA Astrophysics Data System (ADS)

Shabalin, A. G.; Yefanov, O. M.; Nosik, V. L.; Bushuev, V. A.; Vartanyants, I. A.

2017-08-01

We present simulations of Bragg coherent x-ray diffractive imaging (CXDI) data from finite crystals in the frame of the dynamical theory of x-ray diffraction. The developed approach is based on a numerical solution of modified Takagi-Taupin equations and can be applied for modeling of a broad range of x-ray diffraction experiments with finite three-dimensional crystals of arbitrary shape also in the presence of strain. We performed simulations for nanocrystals of a cubic and hemispherical shape of different sizes and provided a detailed analysis of artifacts in the Bragg CXDI reconstructions introduced by the dynamical diffraction. Based on our theoretical analysis we developed an analytical procedure to treat effects of refraction and absorption in the reconstruction. Our results elucidate limitations for the kinematical approach in the Bragg CXDI and suggest a natural criterion to distinguish between kinematical and dynamical cases in coherent x-ray diffraction on a finite crystal.

X-ray source for mammography

DOEpatents

Logan, C.M.

1994-12-20

An x-ray source is described utilizing anode material which shifts the output spectrum to higher energy and thereby obtains higher penetrating ability for screening mammography application, than the currently utilized anode material. The currently used anode material (molybdenum) produces an energy x-ray spectrum of 17.5/19.6 keV, which using the anode material of this invention (e.g. silver, rhodium, and tungsten) the x-ray spectrum would be in the 20-35 keV region. Thus, the anode material of this invention provides for imaging of breasts with higher than average x-ray opacity without increase of the radiation dose, and thus reduces the risk of induced breast cancer due to the radiation dose administered for mammograms. 6 figures.

Observation of electromigration in a Cu thin line by in situ coherent x-ray diffraction microscopy

NASA Astrophysics Data System (ADS)

Takahashi, Yukio; Nishino, Yoshinori; Furukawa, Hayato; Kubo, Hideto; Yamauchi, Kazuto; Ishikawa, Tetsuya; Matsubara, Eiichiro

2009-06-01

Electromigration (EM) in a 1-μm-thick Cu thin line was investigated by in situ coherent x-ray diffraction microscopy (CXDM). Characteristic x-ray speckle patterns due to both EM-induced voids and thermal deformation in the thin line were observed in the coherent x-ray diffraction patterns. Both parts of the voids and the deformation were successfully visualized in the images reconstructed from the diffraction patterns. This result not only represents the first demonstration of the visualization of structural changes in metallic materials by in situ CXDM but is also an important step toward studying the structural dynamics of nanomaterials using x-ray free-electron lasers in the near future.

Investigating the local structure of B-site cations in (1-x)BaTiO3-xBiScO3 and (1-x)PbTiO3-xBiScO3 using X-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Blanchard, Peter E. R.; Grosvenor, Andrew P.

2018-05-01

The structural properties of (1-x)BaTiO3-xBiScO3 and (1-x)PbTiO3-xBiScO3 were investigated using powder X-ray diffraction and X-ray absorption spectroscopy. Diffraction measurements confirmed that substituting small amounts of BiScO3 into BaTiO3 initially stabilizes a cubic phase at x = 0.2 before impurity phases begin to form at x = 0.5. BiScO3 substitution also resulted in noticeable changes in the local coordination environment of Ti4+. X-ray absorption near-edge spectroscopy (XANES) analysis showed that replacing Ti4+ with Sc3+ results in an increase in the off-centre displacement of Ti4+ cations. Surprisingly, BiScO3 substitution has no effect on the displacement of the Ti4+ cation in the (1-x)PbTiO3-xBiScO3 solid solution.

PIXE and XRF Analysis of Roman Denarii

NASA Astrophysics Data System (ADS)

Fasano, Cecilia; Raddell, Mark; Manukyan, Khachatur; Stech, Edward; Wiescher, Michael

2017-09-01

A set of Roman Denarii from the republican to the imperial period (140BC-240AD) has been studied using X-ray fluorescent (XRF) scanning and proton induced x-ray emission (PIXE) techniques. XRF and PIXE are commonly used in the study of cultural heritage objects because they are nondestructive. The combination of these two methods is also unique because of the ability to penetrate the sample with a broader spectrum of depths and energies than either could achieve on its own. The coins are from a large span of Roman history and their analysis serves to follow the economic and political change of the era using the relative silver and copper contents in each sample. In addition to analyzing the samples, the study sought to compare these two common analysis techniques and to explore the use of a standard to examine any shortcomings in either of the methods. Data sets were compared and then adjusted to a calibration curve which was created from the analysis of a number of standard solutions. The concentrations of the standard solutions were confirmed using inductively coupled plasma spectroscopy. Through this we were able to assemble results which will progress the basis of understanding of PIXE and XRF techniques as well as increase the wealth of knowledge of Ancient Roman currency.

Grazing Incidence Optics for X-rays Interferometry

NASA Technical Reports Server (NTRS)

Shipley, Ann; Zissa, David; Cash, Webster; Joy, Marshall

1999-01-01

Grazing incidence mirror parameters and constraints for x-ray interferometry are described. We present interferometer system tolerances and ray trace results used to define mirror surface accuracy requirements. Mirror material, surface figure, roughness, and geometry are evaluated based on analysis results. We also discuss mirror mount design constraints, finite element analysis, environmental issues, and solutions. Challenges associated with quantifying high accuracy mirror surface quality are addressed and test results are compared with theoretical predictions.

Specific physical and chemical properties of two modifications of poly(N-vinylcaprolcatam)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chihacheva, I. P.; Timaeva, O. I.; Kuz’micheva, G. M., E-mail: galina-kuzmicheva@list.ru

2016-05-15

Two modifications of poly(N-vinylcaprolactam)—PVCL25 and PVCL40 (drying of a PVCL solution at 25 and 40°C, respectively)—as powdered films and their solutions were systematically investigated for the first time. Powders were studied by X-ray diffraction, IR spectroscopy, scanning electron microscopy, low-temperature krypton adsorption, and differential scanning calorimetry. Solutions were studied by smallangle X-ray scattering and dynamic light scattering. It was demonstrated that powders of PVCL25 and PVCL40 differ in the characteristics of the sub- and microstructure and in the water content and the solutions differ in the particle size. The relationships between the characteristics of the systems in the solid andmore » liquid state and between the hydrodynamic diameter of PVCL particles in solution and their coagulation time were found.« less

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

PubMed

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. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kunnus, Kristjan; Josefsson, Ida; Rajkovic, Ivan

Here, ultrafast electronic and structural dynamics of matter govern rate and selectivity of chemical reactions, as well as phase transitions and efficient switching in functional materials. Since x-rays determine electronic and structural properties with elemental, chemical, orbital and magnetic selectivity, short pulse x-ray sources have become central enablers of ultrafast science. Despite of these strengths, ultrafast x-rays have been poor at picking up excited state moieties from the unexcited ones. With time-resolved anti-Stokes resonant x-ray Raman scattering (AS-RXRS) performed at the LCLS, and ab initio theory we establish background free excited state selectivity in addition to the elemental, chemical, orbitalmore » and magnetic selectivity of x-rays. This unparalleled selectivity extracts low concentration excited state species along the pathway of photo induced ligand exchange of Fe(CO)5 in ethanol. Conceptually a full theoretical treatment of all accessible insights to excited state dynamics with AS-RXRS with transform-limited x-ray pulses is given—which will be covered experimentally by upcoming transform-limited x-ray sources.« less

Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics

DOE PAGES

Kunnus, Kristjan; Josefsson, Ida; Rajkovic, Ivan; ...

2016-10-07

Here, ultrafast electronic and structural dynamics of matter govern rate and selectivity of chemical reactions, as well as phase transitions and efficient switching in functional materials. Since x-rays determine electronic and structural properties with elemental, chemical, orbital and magnetic selectivity, short pulse x-ray sources have become central enablers of ultrafast science. Despite of these strengths, ultrafast x-rays have been poor at picking up excited state moieties from the unexcited ones. With time-resolved anti-Stokes resonant x-ray Raman scattering (AS-RXRS) performed at the LCLS, and ab initio theory we establish background free excited state selectivity in addition to the elemental, chemical, orbitalmore » and magnetic selectivity of x-rays. This unparalleled selectivity extracts low concentration excited state species along the pathway of photo induced ligand exchange of Fe(CO)5 in ethanol. Conceptually a full theoretical treatment of all accessible insights to excited state dynamics with AS-RXRS with transform-limited x-ray pulses is given—which will be covered experimentally by upcoming transform-limited x-ray sources.« less

Gain dynamics in a soft X-ray laser ampli er perturbed by a strong injected X-ray eld

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yong; Wang, Shoujun; Oliva, E

2014-01-01

Seeding soft X-ray plasma ampli ers with high harmonics has been demonstrated to generate high-brightness soft X-ray laser pulses with full spatial and temporal coherence. The interaction between the injected coherent eld and the swept-gain medium has been modelled. However, no exper- iment has been conducted to probe the gain dynamics when perturbed by a strong external seed eld. Here, we report the rst X-ray pump X-ray probe measurement of the nonlinear response of a plasma ampli er perturbed by a strong soft X-ray ultra-short pulse. We injected a sequence of two time-delayed high-harmonic pulses (l518.9 nm) into a collisionallymore » excited nickel-like molybdenum plasma to measure with femto-second resolution the gain depletion induced by the saturated ampli cation of the high-harmonic pump and its subsequent recovery. The measured fast gain recovery in 1.5 1.75 ps con rms the possibility to generate ultra-intense, fully phase-coherent soft X-ray lasers by chirped pulse ampli cation in plasma ampli ers.« less

Investigating Li 2NiO 2–Li 2CuO 2 Solid Solutions as High-Capacity Cathode Materials for Li-Ion Batteries

DOE PAGES

Xu, Jing; Renfrew, Sara; Marcus, Matthew A.; ...

2017-05-11

Li 2Ni 1–xCu xO 2 solid solutions were prepared by a solid-state method to study the correlation between composition and electrochemical performance. Cu incorporation improved the phase purity of Li 2Ni 1–xCu xO 2 with orthorhombic Immm structure, resulting in enhanced capacity. However, the electrochemical profiles suggested Cu incorporation did not prevent irreversible phase transformation during the electrochemical process, instead, it likely influenced the phase transformation upon lithium removal. By combining ex situ X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and differential electrochemical mass spectrometry (DEMS) measurements, this study elucidates the relevant phase transformation (e.g., crystal structure, local environment, andmore » charge compensation) and participation of electrons from lattice oxygen during the first cycle in these complex oxides.« less

Weapons of mass destruction, WMD.

PubMed

Vogel, H

2007-08-01

Since the invasion into Iraq in 2003, weapons of mass destruction (WMD), have come to general notice; they include today chemical, biological, and atomic/nuclear weapons, (CW, BW, and AW). Radiological findings shall be described. X-ray findings of victims of WMD are described. From CW, own observations are reported. Examples of (possible) X-ray findings of victims of BW are described. AW may induce radiation disease. Exposure to sulfur-lost induces severe bronchitis; if the radiograph shows pulmonary infiltrations, the prognosis is bad; a late consequence maybe bronchiectasis. BW can be based on bacteria, virus or toxins. An approach of the X-ray findings for BW victims is based on the assumption that the disease induced by BW has the same (or a similar) clinic and radiology as that induced by the original microorganism or by the unchanged toxism. This approximation may have its limits, if the germ or toxin has been modified. In survivors of AW, the radiology is probably that of victims of thermal radiation and blast. WMD seem to be a real or a possible threat. They can be used in war, in terrorist attacks, in crime, and in action of secret services. In case that WMD are employed, X-ray diagnostic will be used to evaluate the prognosis (triage) and the risk of infection.

LABORATORY MEASUREMENTS COMPELLINGLY SUPPORT A CHARGE-EXCHANGE MECHANISM FOR THE “DARK MATTER” ∼3.5 keV X-Ray LINE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shah, Chintan; Dobrodey, Stepan; Bernitt, Sven

2016-12-10

The reported observations of an unidentified X-ray line feature at ∼3.5 keV have driven a lively discussion about its possible dark matter origin. Motivated by this, we have measured the K-shell X-ray spectra of highly ionized bare sulfur ions following charge exchange with gaseous molecules in an electron beam ion trap, as a source of or a contributor to this X-ray line. We produced S{sup 16+} and S{sup 15+} ions and let them capture electrons in collision with those molecules with the electron beam turned off while recording X-ray spectra. We observed a charge-exchange-induced X-ray feature at the Lyman seriesmore » limit (3.47 ± 0.06 keV). The inferred X-ray energy is in full agreement with the reported astrophysical observations and supports the novel scenario proposed by Gu et al.« less

X-ray-induced apoptosis of BEL-7402 cell line enhanced by extremely low frequency electromagnetic field in vitro.

PubMed

Jian, Wen; Wei, Zhao; Zhiqiang, Cheng; Zheng, Fang

2009-02-01

This study was designed to test whether extremely low frequency electromagnetic field (ELF-EMF) could enhance the apoptosis-induction effect of X-ray radiotherapy on liver cancer cell line BEL-7402 in vitro. EMF exposure was performed inside an energized solenoid coil. X-ray irradiation was performed using a linear accelerator. Apoptosis rates of BEL-7402 cells were analyzed using Annexin V-Fit Apoptosis Detection kit. Apoptosis rates of EMF group and sham EMF group were compared when combined with X-ray irradiation. Our results suggested that the apoptosis rate of BEL-7402 cells exposed to low doses of X-ray irradiation could be significantly increased by EMF. More EMF exposures obtain significantly higher apoptosis rates than fewer EMF exposures when combined with 2 Gy X-ray irradiation. These findings suggested that ELF-EMF could augment the cell apoptosis effects of low doses of X-ray irradiation on BEL-7402 cells in a synergistic and cumulative way. Copyright 2008 Wiley-Liss, Inc.

REgolith X-Ray Imaging Spectrometer (REXIS) Aboard NASA’s OSIRIS-REx Mission

NASA Astrophysics Data System (ADS)

Hong, JaeSub; Allen, Branden; Grindlay, Jonathan E.; Binzel, Richard P.; Masterson, Rebecca; Inamdar, Niraj K; Chodas, Mark; Smith, Matthew W; Bautz, Mark W.; Kissel, Steven E; Villasenor, Jesus Noel; Oprescu, Antonia

2014-06-01

The REgolith X-Ray Imaging Spectrometer (REXIS) is a student-led instrument being designed, built, and operated as a collaborative effort involving MIT and Harvard. It is a part of NASA's OSIRIS-REx mission, which is scheduled for launch in September of 2016 for a rendezvous with, and collection of a sample from the surface of the primitive carbonaceous chondrite-like asteroid 101955 Bennu in 2019. REXIS will determine spatial variations in elemental composition of Bennu's surface through solar-induced X-ray fluorescence. REXIS consists of four X-ray CCDs in the detector plane and an X-ray mask. It is the first coded-aperture X-ray telescope in a planetary mission, which combines the benefit of high X-ray throughput of wide-field collimation with imaging capability of a coded-mask, enabling detection of elemental surface distributions at approximately 50-200 m scales. We present an overview of the REXIS instrument and the expected performance.

Effects of X-ray irradiation on the Eu3+ → Eu2+ conversion in CaAl2O4 phosphors

NASA Astrophysics Data System (ADS)

Gomes, Manassés A.; Carvalho, Jéssica C.; Andrade, Adriano B.; Rezende, Marcos V.; Macedo, Zélia S.; Valerio, Mário E. G.

2018-01-01

This paper reports structural and luminescence properties of Eu-doped CaAl2O4 produced by an alternative sol-gel method using coconut water. Results of differential thermal analysis (DTA), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) allowed us to identify the best synthesis conditions for sample preparation. Simultaneous measurements of X-ray absorption spectroscopy (XAS) and X-ray excited optical luminescence (XEOL) were also performed in the X-ray energy range of the Eu LIII edge. Results from photoluminescence (PL) showed only the characteristic Eu3+ emission. However, radioluminescence emission spectra from Eu-doped CaAl2O4 shows a process of conversion of Eu3+ to Eu2+, which is induced by X-ray irradiation and is dependent on the radiation dose energy. X-ray absorption near edge structure (XANES) measurements corroborate Eu reduction due to irradiation, showing that only the Eu3+ ion is present in stable form in the CaAl2O4.

Detailed transient heme structures of Mb-CO in solution after CO dissociation: an X-ray transient absorption spectroscopic study.

PubMed

Stickrath, Andrew B; Mara, Michael W; Lockard, Jenny V; Harpham, Michael R; Huang, Jier; Zhang, Xiaoyi; Attenkofer, Klaus; Chen, Lin X

2013-04-25

Although understanding the structural dynamics associated with ligand photodissociation is necessary in order to correlate structure and function in biological systems, few techniques are capable of measuring the ultrafast dynamics of these systems in solution-phase at room temperature. We present here a detailed X-ray transient absorption (XTA) study of the photodissociation of CO-bound myoglobin (Fe(II)CO-Mb) in room-temperature aqueous buffer solution with a time resolution of 80 ps, along with a general procedure for handling biological samples under the harsh experimental conditions that transient X-ray experiments entail. The XTA spectra of (Fe(II)CO-Mb) exhibit significant XANES and XAFS alterations following 527 nm excitation, which remain unchanged for >47 μs. These spectral changes indicate loss of the CO ligand, resulting in a five-coordinate, domed heme, and significant energetic reorganization of the 3d orbitals of the Fe center. With the current experimental setup, each X-ray pulse in the pulse train, separated by ~153 ns, can be separately discriminated, yielding snapshots of the myoglobin evolution over time. These methods can be easily applied to other biological systems, allowing for simultaneous structural and electronic measurements of any biological system with both ultrafast and slow time resolutions, effectively mapping out all of the samples' relevant physiological processes.

Projection of the Liquidus Surface of the Co - Sn - Bi System

NASA Astrophysics Data System (ADS)

Abilov, Ch. I.; Allazov, M. R.; Sadygova, S. G.

2016-11-01

The crystallization behavior of phases in alloys of the Co - Sn - Bi system is studied by the methods of differential thermal (DTA), x-ray phase (XRP) and x-ray diffraction (XRD) analyses and hardness measurement. The projection of the liquidus surface is plotted. The boundaries of layering, the development of the monovariant processes, and the coordinates of the nonvariant equilibrium compositions are determined. Compositions of (Co3Sn2)1 - x Bi x solid solutions suitable for the production of antifriction materials are suggested.

A gold cyano complex in nitromethane: MD simulation and X-ray diffraction.

PubMed

Probst, Michael; Injan, Natcha; Megyes, Tünde; Bako, Imre; Balint, Szabolcz; Limtrakul, Jumras; Nazmutdinov, Renat; Mitev, Pavlin D; Hermansson, Kersti

2012-06-29

The solvation structure around the dicyanoaurate(I) anion (Au(CN) 2 - ) in a dilute nitromethane (CH 3 NO 2 ) solution is presented from X-ray diffraction measurements and molecular dynamics simulation (NVT ensemble, 460 nitromethane molecules at room temperature). The simulations are based on a new solute-solvent force-field fitted to a training set of quantum-chemically derived interaction energies. Radial distribution functions from experiment and simulation are in good agreement. The solvation structure has been further elucidated from MD data. Several shells can be identified. We obtain a solvation number of 13-17 nitromethane molecules with a strong preference to be oriented with their methyl groups towards the solute.

A Guide for Planning Facilities for Occupational Preparation Programs for Medical X-Ray Technicians. Research 31.

ERIC Educational Resources Information Center

Macconnell, James D.; And Others

The major purpose of this guide is to develop the necessary information for the writing of educational specifications to house medical x-ray technician programs. The guide is also designed to: (1) assist planners in the formation of creative housing solutions for desired educational programs, (2) prevent important considerations from being…

Development of a spectro-electrochemical cell for soft X-ray photon-in photon-out spectroscopy

NASA Astrophysics Data System (ADS)

Ishihara, Tomoko; Tokushima, Takashi; Horikawa, Yuka; Kato, Masaru; Yagi, Ichizo

2017-10-01

We developed a spectro-electrochemical cell for X-ray absorption and X-ray emission spectroscopy, which are element-specific methods to study local electronic structures in the soft X-ray region. In the usual electrochemical measurement setup, the electrode is placed in solution, and the surface/interface region of the electrode is not normally accessible by soft X-rays that have low penetration depth in liquids. To realize soft X-ray observation of electrochemical reactions, a 15-nm-thick Pt layer was deposited on a 150-nm-thick film window with an adhesive 3-nm-thick Ti layer for use as both the working electrode and the separator window between vacuum and a sample liquid under atmospheric pressure. The designed three-electrode electrochemical cell consists of a Pt film on a SiC window, a platinized Pt wire, and a commercial Ag|AgCl electrode as the working, counter, and reference electrodes, respectively. The functionality of the cell was tested by cyclic voltammetry and X-ray absorption and emission spectroscopy. As a demonstration, the electroplating of Pb on the Pt/SiC membrane window was measured by X-ray absorption and real-time monitoring of fluorescence intensity at the O 1s excitation.

Topics in Astrophysical X-Ray and Gamma Ray Spectroscopy. Ph.D. Thesis - Maryland Univ.

NASA Technical Reports Server (NTRS)

Bussard, R. W.

1978-01-01

A number of topics relating to astrophysical observations that have already been made or are currently planned of spectral features, mostly emission lines, in the X-ray and gamma ray region of the electromagnetic spectrum are investigated. These topics include: the production of characteristic X-ray and gamma ray lines by nonthermal ions, spectral features induced by processes occurring in strong magnetic fields, and the positron annihilation line at 0.5 MeV. The rate of X-ray production at 6.8 keV by the 2p to 1s transition in fast hydrogen- and helium-like iron ions, following both electron capture to excited levels and collisional excitation is calculated. The cross section for electron-ion Coulomb collisions in strong fields is also calculated.

Application of micron X-ray CT based on micro-PIXE to investigate the distribution of Cs in silt particles for environmental remediation in Fukushima Prefecture

NASA Astrophysics Data System (ADS)

Ishii, Keizo; Hatakeyama, Taisuke; Itoh, Shin; Sata, Daichi; Ohnuma, Tohru; Yamaguchi, Toshiro; Arai, Hiromu; Arai, Hirotsugu; Matsuyama, Shigeo; Terakawa, Atsuki; Kim, Seong-Yun

2016-03-01

We used X-ray computed tomography (CT) using characteristic X-rays produced in micro-particle-induced X-ray emission (PIXE) to investigate the internal structure of silt particles and develop new methods to decontaminate soil containing radioactive cesium. We obtained 3D attenuation coefficient images of silt particles with a diameter of approximately 100 μm for V K and Cr K X-rays. Owing to the absorption edges of the Cs L-shell, the differences between the V K and Cr K X-ray images revealed the spatial distribution of Cs atoms in the silt particles. Cs atoms were distributed over the surfaces of the silt particles to a thickness of approximately 10 μm. This information is useful for the decontamination of silt contaminated by radiation from the Fukushima Daiichi nuclear disaster.

Combining X-ray and neutron crystallography with spectroscopy.

PubMed

Kwon, Hanna; Smith, Oliver; Raven, Emma Lloyd; Moody, Peter C E

2017-02-01

X-ray protein crystallography has, through the determination of the three-dimensional structures of enzymes and their complexes, been essential to the understanding of biological chemistry. However, as X-rays are scattered by electrons, the technique has difficulty locating the presence and position of H atoms (and cannot locate H + ions), knowledge of which is often crucially important for the understanding of enzyme mechanism. Furthermore, X-ray irradiation, through photoelectronic effects, will perturb the redox state in the crystal. By using single-crystal spectrophotometry, reactions taking place in the crystal can be monitored, either to trap intermediates or follow photoreduction during X-ray data collection. By using neutron crystallography, the positions of H atoms can be located, as it is the nuclei rather than the electrons that scatter neutrons, and the scattering length is not determined by the atomic number. Combining the two techniques allows much greater insight into both reaction mechanism and X-ray-induced photoreduction.

Hard X-ray-induced damage on carbon–binder matrix for in situ synchrotron transmission X-ray microscopy tomography of Li-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Cheolwoong; Kang, Huixiao; De Andrade, Vincent

2017-03-21

The electrode of Li-ion batteries is required to be chemically and mechanically stable in the electrolyte environment forin situmonitoring by transmission X-ray microscopy (TXM). Evidence has shown that continuous irradiation has an impact on the microstructure and the electrochemical performance of the electrode. To identify the root cause of the radiation damage, a wire-shaped electrode is soaked in an electrolyte in a quartz capillary and monitored using TXM under hard X-ray illumination. The results show that expansion of the carbon–binder matrix by the accumulated X-ray dose is the key factor of radiation damage. Forin situTXM tomography, intermittent X-ray exposure duringmore » image capturing can be used to avoid the morphology change caused by radiation damage on the carbon–binder matrix.« less

Non-induction of radioadaptive response in zebrafish embryos by neutrons

PubMed Central

Ng, Candy Y.P.; Kong, Eva Y.; Kobayashi, Alisa; Suya, Noriyoshi; Uchihori, Yukio; Cheng, Shuk Han; Konishi, Teruaki; Yu, Kwan Ngok

2016-01-01

In vivo neutron-induced radioadaptive response (RAR) was studied using zebrafish (Danio rerio) embryos. The Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility at the National Institute of Radiological Sciences (NIRS), Japan, was employed to provide 2-MeV neutrons. Neutron doses of 0.6, 1, 25, 50 and 100 mGy were chosen as priming doses. An X-ray dose of 2 Gy was chosen as the challenging dose. Zebrafish embryos were dechorionated at 4 h post fertilization (hpf), irradiated with a chosen neutron dose at 5 hpf and the X-ray dose at 10 hpf. The responses of embryos were assessed at 25 hpf through the number of apoptotic signals. None of the neutron doses studied could induce RAR. Non-induction of RAR in embryos having received 0.6- and 1-mGy neutron doses was attributed to neutron-induced hormesis, which maintained the number of damaged cells at below the threshold for RAR induction. On the other hand, non-induction of RAR in embryos having received 25-, 50- and 100-mGy neutron doses was explained by gamma-ray hormesis, which mitigated neutron-induced damages through triggering high-fidelity DNA repair and removal of aberrant cells through apoptosis. Separate experimental results were obtained to verify that high-energy photons could disable RAR. Specifically, 5- or 10-mGy X-rays disabled the RAR induced by a priming dose of 0.88 mGy of alpha particles delivered to 5-hpf zebrafish embryos against a challenging dose of 2 Gy of X-rays delivered to the embryos at 10 hpf. PMID:26850927

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xi; Wang, Shanshan; Ghiviriga, Ion

A novel synthetic method to create gold based metallo–oligomers/polymers via the combination of inorganic click (iClick) with intermolecular aurophilic interactions is demonstrated. Complexes [PEt 3Au] 4(μ-N 3C 2C 6H 5) (1) and [PPhMe 2Au] 43C 2C 6H 5) (2) and {[PEt 3Au] 4[(μ-N 3C 2) 2-9,9-dihexyl-9H-fluorene]} n (8) have been synthesized via iClick. The tetranuclear structures of 1 and 2, induced by aurophilic bonding, are confirmed in the solid state through single crystal X-ray diffraction experiments and in solution via variable temperature NMR spectroscopy. The extended 1D structure of 8 is constructed by aurophilic induced self-assembly. 1H DOSY NMR analysismore » reveals that the aurophilic bonds in 1, 2, and 8 are retained in the solution phase. The degree of polymerization within complex 8 is temperature and concentration dependent, as determined by 1H DOSY NMR. The complex 8 is a rare example of a solution stable higher ordered structure linked by aurophilic interactions.« less

Plasma-induced grafting of acrylic acid on bentonite for the removal of U(VI) from aqueous solution

NASA Astrophysics Data System (ADS)

Hongshan, ZHU; Shengxia, DUAN; Lei, CHEN; Ahmed, ALSAEDI; Tasawar, HAYAT; Jiaxing, LI

2017-11-01

Fabrication of reusable adsorbents with satisfactory adsorption capacity and using environment-friendly preparation processes is required for the environment-related applications. In this study, acrylic acid (AA) was grafted onto bentonite (BT) to generate an AA-graft-BT (AA-g-BT) composite using a plasma-induced grafting technique considered to be an environment-friendly method. The as-prepared composite was characterized by scanning electron microscopy, x-ray powder diffraction, thermal gravity analysis, Fourier transform infrared spectroscopy and Barrett-Emmett-Teller analysis, demonstrating the successful grafting of AA onto BT. In addition, the removal of uranium(VI) (U(VI)) from contaminated aqueous solutions was examined using the as-prepared composite. The influencing factors, including contact time, pH value, ionic strength, temperature, and initial concentration, for the removal of U(VI) were investigated by batch experiments. The experimental process fitted best with the pseudo-second-order kinetic and the Langmuir models. Moreover, thermodynamic investigation revealed a spontaneous and endothermic process. Compared with previous adsorbents, AA-g-BT has potential practical applications in treating U(VI)-contaminated solutions.

Structural and magnetic aspects of La4(Co1-xNix)3O10+δ (0 ≤ x ≤ 1)

NASA Astrophysics Data System (ADS)

Nagell, Marius Uv; Kumar, Susmit; Sørby, Magnus H.; Fjellvåg, Helmer; Olafsen Sjåstad, Anja

2015-10-01

The Ruddlesden-Popper (RP3) type oxides, La4Co3O10+δ and La4Ni3O10+δ, form a complete solid solution. Powder X-ray and neutron diffraction data show that La4(Co1-xNix)3O10+δ is isostructural to the monoclinic La4Co3O10+δ structure (P21/a) described for all compositions without any further structural distortions as suggested in the literature. A slight elongation of the Co/Ni-O bonds facing the rock salt interlayer occurs for Ni-rich compositions. The magnetic properties of the solid solution series are mapped in the temperature range from 4 to 300 K, and the results are presented in a magnetic phase diagram. Three regimes with antiferromagnetic order (AF) exist at low temperatures, TN < 10 - 30 K. For x = 0.00, the AF is ascribed to Co(II), whereas a broader AF regime around x = 0.50 is ascribed mainly to Ni(II). Pauli paramagnetism is observed close to metallic La4Ni3O10+δ, x > 0.80. The possibility to tune the oxidation state of the transition metal atoms is demonstrated for La4Co3O10+δ, and exemplified by weakening of a temperature-induced spin transition at around 480 K.

Pressure dependence of the monoclinic phase in (1–x)Pb(Mg 1/3Nb 2/3)O 3-xPbTiO₃ solid solutions

DOE PAGES

Ahart, Muhtar; Sinogeikin, Stanislav; Shebanova, Olga; ...

2012-12-26

We combine high-pressure x-ray diffraction, high-pressure Raman scattering, and optical microscopy to investigate a series of (1–x)Pb(Mg 1/3Nb 2/3)O 3-xPbTiO₃ (PMN-xPT) solid solutions (x=0.2, 0.3, 0.33, 0.35, 0.37, 0.4) in diamond anvil cells up to 20 GPa at 300 K. The Raman spectra show a peak centered at 380 cm⁻¹ starting above 6 GPa for all samples, in agreement with previous observations. X-ray diffraction measurements are consistent with this spectral change indicating a structural phase transition; we find that the triplet at the pseudocubic (220) Bragg peak merges into a doublet above 6 GPa. Our results indicate that the morphotropicmore » phase boundary region (x=0.33–0.37) with the presence of monoclinic symmetry persists up to 7 GPa. The pressure dependence of ferroelectric domains in PMN-0.32PT single crystals was observed using a polarizing optical microscope. The domain wall density decreases with pressure and the domains disappear at a modest pressure of 3 GPa. We propose a pressure-composition phase diagram for PMN-xPT solid solutions.« less

Stimulated x-ray emission spectroscopy in transition metal complexes

DOE PAGES

Kroll, Thomas; Weninger, Clemens; Alonso-Mori, Roberto; ...

2018-03-27

We report the observation and analysis of the gain curve of amplified Kα X-ray emission from solutions of Mn(II) and Mn(VII) complexes using an X-ray free electron laser to create the 1s core-hole population inversion. We find spectra at amplification levels extending over four orders of magnitude until saturation. We observe bandwidths below the Mn 1s core-hole lifetime broadening in the onset of the stimulated emission. In the exponential amplification regime the resolution corrected spectral width of ~1.7 eV FWHM is constant over three orders of magnitude, pointing to the build-up of transform limited pulses of ~1fs duration. Driving the amplification into saturation leads to broadening and shift of the line. Importantly, the chemical sensitivity of the stimulated X-ray emission to the Mn oxidation state is preserved at power densities ofmore » $$\\sim10 20$$~W/cm 2 for the incoming X-ray pulses. Differences in signal sensitivity and spectral information compared to conventional (spontaneous) X-ray emission spectroscopy are discussed. Our findings build a baseline for nonlinear X-ray spectroscopy for a wide range of transition metal complexes in inorganic chemistry, catalysis and materials science.« less

Stimulated x-ray emission spectroscopy in transition metal complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kroll, Thomas; Weninger, Clemens; Alonso-Mori, Roberto

We report the observation and analysis of the gain curve of amplified Kα X-ray emission from solutions of Mn(II) and Mn(VII) complexes using an X-ray free electron laser to create the 1s core-hole population inversion. We find spectra at amplification levels extending over four orders of magnitude until saturation. We observe bandwidths below the Mn 1s core-hole lifetime broadening in the onset of the stimulated emission. In the exponential amplification regime the resolution corrected spectral width of ~1.7 eV FWHM is constant over three orders of magnitude, pointing to the build-up of transform limited pulses of ~1fs duration. Driving the amplification into saturation leads to broadening and shift of the line. Importantly, the chemical sensitivity of the stimulated X-ray emission to the Mn oxidation state is preserved at power densities ofmore » $$\\sim10 20$$~W/cm 2 for the incoming X-ray pulses. Differences in signal sensitivity and spectral information compared to conventional (spontaneous) X-ray emission spectroscopy are discussed. Our findings build a baseline for nonlinear X-ray spectroscopy for a wide range of transition metal complexes in inorganic chemistry, catalysis and materials science.« less

Stimulated X-Ray Emission Spectroscopy in Transition Metal Complexes

NASA Astrophysics Data System (ADS)

Kroll, Thomas; Weninger, Clemens; Alonso-Mori, Roberto; Sokaras, Dimosthenis; Zhu, Diling; Mercadier, Laurent; Majety, Vinay P.; Marinelli, Agostino; Lutman, Alberto; Guetg, Marc W.; Decker, Franz-Josef; Boutet, Sébastien; Aquila, Andy; Koglin, Jason; Koralek, Jake; DePonte, Daniel P.; Kern, Jan; Fuller, Franklin D.; Pastor, Ernest; Fransson, Thomas; Zhang, Yu; Yano, Junko; Yachandra, Vittal K.; Rohringer, Nina; Bergmann, Uwe

2018-03-01

We report the observation and analysis of the gain curve of amplified K α x-ray emission from solutions of Mn(II) and Mn(VII) complexes using an x-ray free electron laser to create the 1 s core-hole population inversion. We find spectra at amplification levels extending over 4 orders of magnitude until saturation. We observe bandwidths below the Mn 1 s core-hole lifetime broadening in the onset of the stimulated emission. In the exponential amplification regime the resolution corrected spectral width of ˜1.7 eV FWHM is constant over 3 orders of magnitude, pointing to the buildup of transform limited pulses of ˜1 fs duration. Driving the amplification into saturation leads to broadening and a shift of the line. Importantly, the chemical sensitivity of the stimulated x-ray emission to the Mn oxidation state is preserved at power densities of ˜1020 W /cm2 for the incoming x-ray pulses. Differences in signal sensitivity and spectral information compared to conventional (spontaneous) x-ray emission spectroscopy are discussed. Our findings build a baseline for nonlinear x-ray spectroscopy for a wide range of transition metal complexes in inorganic chemistry, catalysis, and materials science.

Organogold oligomers: Exploiting iClick and aurophilic cluster formation to prepare solution stable Au 4 repeating units

DOE PAGES

Yang, Xi; Wang, Shanshan; Ghiviriga, Ion; ...

2015-05-19

A novel synthetic method to create gold based metallo–oligomers/polymers via the combination of inorganic click (iClick) with intermolecular aurophilic interactions is demonstrated. Complexes [PEt 3Au] 4(μ-N 3C 2C 6H 5) (1) and [PPhMe 2Au] 43C 2C 6H 5) (2) and {[PEt 3Au] 4[(μ-N 3C 2) 2-9,9-dihexyl-9H-fluorene]} n (8) have been synthesized via iClick. The tetranuclear structures of 1 and 2, induced by aurophilic bonding, are confirmed in the solid state through single crystal X-ray diffraction experiments and in solution via variable temperature NMR spectroscopy. The extended 1D structure of 8 is constructed by aurophilic induced self-assembly. 1H DOSY NMR analysismore » reveals that the aurophilic bonds in 1, 2, and 8 are retained in the solution phase. The degree of polymerization within complex 8 is temperature and concentration dependent, as determined by 1H DOSY NMR. The complex 8 is a rare example of a solution stable higher ordered structure linked by aurophilic interactions.« less

X-Ray-induced Deuterium Enrichment of N-rich Organics in Protoplanetary Disks: An Experimental Investigation Using Synchrotron Light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gavilan, Lisseth; Carrasco, Nathalie; Remusat, Laurent

The deuterium enrichment of organics in the interstellar medium, protoplanetary disks, and meteorites has been proposed to be the result of ionizing radiation. The goal of this study is to simulate and quantify the effects of soft X-rays (0.1–2 keV), an important component of stellar radiation fields illuminating protoplanetary disks, on the refractory organics present in the disks. We prepared tholins, nitrogen-rich organic analogs to solids found in several astrophysical environments, e.g., Titan’s atmosphere, cometary surfaces, and protoplanetary disks, via plasma deposition. Controlled irradiation experiments with soft X-rays at 0.5 and 1.3 keV were performed at the SEXTANTS beamline ofmore » the SOLEIL synchrotron, and were immediately followed by ex-situ infrared, Raman, and isotopic diagnostics. Infrared spectroscopy revealed the preferential loss of singly bonded groups (N–H, C–H, and R–N≡C) and the formation of sp{sup 3} carbon defects with signatures at ∼1250–1300 cm{sup −1}. Raman analysis revealed that, while the length of polyaromatic units is only slightly modified, the introduction of defects leads to structural amorphization. Finally, tholins were measured via secondary ion mass spectrometry to quantify the D, H, and C elemental abundances in the irradiated versus non-irradiated areas. Isotopic analysis revealed that significant D-enrichment is induced by X-ray irradiation. Our results are compared to previous experimental studies involving the thermal degradation and electron irradiation of organics. The penetration depth of soft X-rays in μ m-sized tholins leads to volume rather than surface modifications: lower-energy X-rays (0.5 keV) induce a larger D-enrichment than 1.3 keV X-rays, reaching a plateau for doses larger than 5 × 10{sup 27} eV cm{sup −3}. Synchrotron fluences fall within the expected soft X-ray fluences in protoplanetary disks, and thus provide evidence of a new non-thermal pathway to deuterium fractionation of organic matter.« less

Auto-rickshaw: an automated crystal structure determination platform as an efficient tool for the validation of an X-ray diffraction experiment.

PubMed

Panjikar, Santosh; Parthasarathy, Venkataraman; Lamzin, Victor S; Weiss, Manfred S; Tucker, Paul A

2005-04-01

The EMBL-Hamburg Automated Crystal Structure Determination Platform is a system that combines a number of existing macromolecular crystallographic computer programs and several decision-makers into a software pipeline for automated and efficient crystal structure determination. The pipeline can be invoked as soon as X-ray data from derivatized protein crystals have been collected and processed. It is controlled by a web-based graphical user interface for data and parameter input, and for monitoring the progress of structure determination. A large number of possible structure-solution paths are encoded in the system and the optimal path is selected by the decision-makers as the structure solution evolves. The processes have been optimized for speed so that the pipeline can be used effectively for validating the X-ray experiment at a synchrotron beamline.

Comptonization of X-rays by low-temperature electrons. [photon wavelength redistribution in cosmic sources

NASA Technical Reports Server (NTRS)

Illarionov, A.; Kallman, T.; Mccray, R.; Ross, R.

1979-01-01

A method is described for calculating the spectrum that results from the Compton scattering of a monochromatic source of X-rays by low-temperature electrons, both for initial-value relaxation problems and for steady-state spatial diffusion problems. The method gives an exact solution of the inital-value problem for evolution of the spectrum in an infinite homogeneous medium if Klein-Nishina corrections to the Thomson cross section are neglected. This, together with approximate solutions for problems in which Klein-Nishina corrections are significant and/or spatial diffusion occurs, shows spectral structure near the original photon wavelength that may be used to infer physical conditions in cosmic X-ray sources. Explicit results, shown for examples of time relaxation in an infinite medium and spatial diffusion through a uniform sphere, are compared with results obtained by Monte Carlo calculations and by solving the appropriate Fokker-Planck equation.

Coherent variability of GX 1+4

NASA Astrophysics Data System (ADS)

Nielsen, Ann-Sofie Bak; Patruno, Alessandro

2018-06-01

The accreting pulsar GX 1+4 is a symbiotic X-ray binary system with a M-type giant star companion. The system has a spin period of about 150 s and a proposed strong magnetic field of 1012-1014G. In this paper we study the coherent variability of the source and attempt to find a phase-coherent solution for the pulsar. We also test for the presence of a pulse phase - flux correlation, similar to what is observed for the accreting millisecond X-ray pulsars, in order to test whether this feature is dependent on the magnetic field strength. We find that no phase coherent solution exists which suggests that the pulsar is accreting plasma from a wind rather than an accretion disc. We also find evidence that the pulse phase is not correlated with the X-ray flux, which strengthens the idea that such relation might be present only in weak magnetic field sources like accreting millisecond pulsars.

Improving Beamline X-ray Optics by Analyzing the Damage to Crystallographic Structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zientek, John; Maj, Jozef; Navrotski, Gary

2015-01-02

The mission of the X-ray Characterization Laboratory in the X-ray Science Division (XSD) at the Advanced Photon Source (APS) is to support both the users and the Optics Fabrication Facility that produces high performance optics for synchrotron X-ray beamlines. The Topography Test Unit (TTU) in the X-ray Lab has been successfully used to characterize diffracting crystals and test monochromators by quantifying residual surface stresses. This topographic method has also been adapted for testing standard X-ray mirrors, characterizing concave crystal optics and in principle, can be used to visualize residual stresses on any optic made from single crystalline material. The TTUmore » has been instrumental in quantitatively determining crystal mounting stresses which are mechanically induced by positioning, holding, and cooling fixtures. It is this quantitative aspect that makes topography so useful since the requirements and responses for crystal optics and X-ray mirrors are quite different. In the case of monochromator crystals, even small residual or induced stresses, on the order of tens of kPa, can cause detrimental distortions to the perfect crystal rocking curves. Mirrors, on the other hand, are much less sensitive to induced stresses where stresses that are an order of magnitude greater can be tolerated. This is due to the fact that the surface rather than the lattice-spacing determines a mirror’s performance. For the highly sensitive crystal optics, it is essential to measure the in-situ rocking curves using topographs as mounting fixtures are adjusted. In this way, high heat-load monochromator crystals can be successfully mounted with minimum stress. Topographical analysis has been shown to be a highly effective method to visualize and quantify the distribution of stresses, to help identify methods that mitigate stresses, and most notably to improve diffractive crystal optic rocking curves.« less

Determination of the conformational ensemble of the TAR RNA by X-ray scattering interferometry

PubMed Central

Walker, Peter

2017-01-01

Abstract The conformational ensembles of structured RNA's are crucial for biological function, but they remain difficult to elucidate experimentally. We demonstrate with HIV-1 TAR RNA that X-ray scattering interferometry (XSI) can be used to determine RNA conformational ensembles. X-ray scattering interferometry (XSI) is based on site-specifically labeling RNA with pairs of heavy atom probes, and precisely measuring the distribution of inter-probe distances that arise from a heterogeneous mixture of RNA solution structures. We show that the XSI-based model of the TAR RNA ensemble closely resembles an independent model derived from NMR-RDC data. Further, we show how the TAR RNA ensemble changes shape at different salt concentrations. Finally, we demonstrate that a single hybrid model of the TAR RNA ensemble simultaneously fits both the XSI and NMR-RDC data set and show that XSI can be combined with NMR-RDC to further improve the quality of the determined ensemble. The results suggest that XSI-RNA will be a powerful approach for characterizing the solution conformational ensembles of RNAs and RNA-protein complexes under diverse solution conditions. PMID:28108663

Small Angle X-Ray Scattering from Lipid-Bound Myelin Basic Protein in Solution

PubMed Central

Haas, H.; Oliveira, C. L. P.; Torriani, I. L.; Polverini, E.; Fasano, A.; Carlone, G.; Cavatorta, P.; Riccio, P.

2004-01-01

The structure of myelin basic protein (MBP), purified from the myelin sheath in both lipid-free (LF-MBP) and lipid-bound (LB-MBP) forms, was investigated in solution by small angle x-ray scattering. The water-soluble LF-MBP, extracted at pH < 3.0 from defatted brain, is the classical preparation of MBP, commonly regarded as an intrinsically unfolded protein. LB-MBP is a lipoprotein-detergent complex extracted from myelin with its native lipidic environment at pH > 7.0. Under all conditions, the scattering from the two protein forms was different, indicating different molecular shapes. For the LB-MBP, well-defined scattering curves were obtained, suggesting that the protein had a unique, compact (but not globular) structure. Furthermore, these data were compatible with earlier results from molecular modeling calculations on the MBP structure which have been refined by us. In contrast, the LF-MBP data were in accordance with the expected open-coil conformation. The results represent the first direct structural information from x-ray scattering measurements on MBP in its native lipidic environment in solution. PMID:14695288

X-ray Reciprocal Space Mapping of Graded Al x Ga1 - x N Films and Nanowires.

PubMed

Stanchu, Hryhorii V; Kuchuk, Andrian V; Kladko, Vasyl P; Ware, Morgan E; Mazur, Yuriy I; Zytkiewicz, Zbigniew R; Belyaev, Alexander E; Salamo, Gregory J

2016-12-01

The depth distribution of strain and composition in graded Al x Ga1 - x N films and nanowires (NWs) are studied theoretically using the kinematical theory of X-ray diffraction. By calculating [Formula: see text] reciprocal space maps (RSMs), we demonstrate significant differences in the intensity distributions from graded Al x Ga1 - x N films and NWs. We attribute these differences to relaxation of the substrate-induced strain on the NWs free side walls. Finally, we demonstrate that the developed X-ray reciprocal space map model allows for reliable depth profiles of strain and Al composition determination in both Al x Ga1 - x N films and NWs.

Energy-correction photon counting pixel for photon energy extraction under pulse pile-up

NASA Astrophysics Data System (ADS)

Lee, Daehee; Park, Kyungjin; Lim, Kyung Taek; Cho, Gyuseong

2017-06-01

A photon counting detector (PCD) has been proposed as an alternative solution to an energy-integrating detector (EID) in medical imaging field due to its high resolution, high efficiency, and low noise. The PCD has expanded to variety of fields such as spectral CT, k-edge imaging, and material decomposition owing to its capability to count and measure the number and the energy of an incident photon, respectively. Nonetheless, pulse pile-up, which is a superimposition of pulses at the output of a charge sensitive amplifier (CSA) in each PC pixel, occurs frequently as the X-ray flux increases due to the finite pulse processing time (PPT) in CSAs. Pulse pile-up induces not only a count loss but also distortion in the measured X-ray spectrum from each PC pixel and thus it is a main constraint on the use of PCDs in high flux X-ray applications. To minimize these effects, an energy-correction PC (ECPC) pixel is proposed to resolve pulse pile-up without cutting off the PPT by adding an energy correction logic (ECL) via a cross detection method (CDM). The ECPC pixel with a size of 200×200 μm2 was fabricated by using a 6-metal 1-poly 0.18 μm CMOS process with a static power consumption of 7.2 μW/pixel. The maximum count rate of the ECPC pixel was extended by approximately three times higher than that of a conventional PC pixel with a PPT of 500 nsec. The X-ray spectrum of 90 kVp, filtered by 3 mm Al filter, was measured as the X-ray current was increased using the CdTe and the ECPC pixel. As a result, the ECPC pixel dramatically reduced the energy spectrum distortion at 2 Mphotons/pixel/s when compared to that of the ERCP pixel with the same 500 nsec PPT.

X-ray induced formation of γ-H2AX foci after full-field digital mammography and digital breast-tomosynthesis.

PubMed

Schwab, Siegfried A; Brand, Michael; Schlude, Ina-Kristin; Wuest, Wolfgang; Meier-Meitinger, Martina; Distel, Luitpold; Schulz-Wendtland, Ruediger; Uder, Michael; Kuefner, Michael A

2013-01-01

To determine in-vivo formation of x-ray induced γ-H2AX foci in systemic blood lymphocytes of patients undergoing full-field digital mammography (FFDM) and to estimate foci after FFDM and digital breast-tomosynthesis (DBT) using a biological phantom model. The study complies with the Declaration of Helsinki and was performed following approval by the ethic committee of the University of Erlangen-Nuremberg. Written informed consent was obtained from every patient. For in-vivo tests, systemic blood lymphocytes were obtained from 20 patients before and after FFDM. In order to compare in-vivo post-exposure with pre-exposure foci levels, the Wilcoxon matched pairs test was used. For in-vitro experiments, isolated blood lymphocytes from healthy volunteers were irradiated at skin and glandular level of a porcine breast using FFDM and DBT. Cells were stained against the phosphorylated histone variant γ-H2AX, and foci representing distinct DNA damages were quantified. Median in-vivo foci level/cell was 0.086 (range 0.067-0.116) before and 0.094 (0.076-0.126) after FFDM (p = 0.0004). In the in-vitro model, the median x-ray induced foci level/cell after FFDM was 0.120 (range 0.086-0.140) at skin level and 0.035 (range 0.030-0.050) at glandular level. After DBT, the median x-ray induced foci level/cell was 0.061 (range 0.040-0.081) at skin level and 0.015 (range 0.006-0.020) at glandular level. In patients, mammography induces a slight but significant increase of γ-H2AX foci in systemic blood lymphocytes. The introduced biological phantom model is suitable for the estimation of x-ray induced DNA damages in breast tissue in different breast imaging techniques.

The Secret Lives of Cepheids: δ Cep—The Prototype of a New Class of Pulsating X-Ray Variable Stars

NASA Astrophysics Data System (ADS)

Engle, Scott G.; Guinan, Edward F.; Harper, Graham M.; Cuntz, Manfred; Remage Evans, Nancy; Neilson, Hilding R.; Fawzy, Diaa E.

2017-03-01

From our Secret Lives of Cepheids program, the prototype Classical Cepheid, δ Cep, is found to be an X-ray source with periodic pulsation-modulated X-ray variations. This finding complements our earlier reported phase-dependent FUV-UV emissions of the star that increase ˜10-20 times with highest fluxes at ˜ 0.90{--}0.95φ , just prior to maximum brightness. Previously δ Cep was found as potentially X-ray variable, using XMM-Newton observations. Additional phase-constrained data were secured with Chandra near X-ray emission peak, to determine if the emission and variability were pulsation-phase-specific to δ Cep and not transient or due to a possible coronally active, cool companion. The Chandra data were combined with prior XMM-Newton observations, and were found to very closely match the previously observed X-ray behavior. From the combined data set, a ˜4 increase in X-ray flux is measured, reaching a peak {L}{{X}} = 1.7 × 1029 erg s-1 near 0.45ϕ. The precise X-ray flux phasing with the star’s pulsation indicates that the emissions arise from the Cepheid and not from a companion. However, it is puzzling that the maximum X-ray flux occurs ˜0.5ϕ (˜3 days) later than the FUV-UV maximum. There are several other potential Cepheid X-ray detections with properties similar to δ Cep, and comparable X-ray variability is indicated for two other Cepheids: β Dor and V473 Lyr. X-ray generating mechanisms in δ Cep and other Cepheids are discussed. If additional Cepheids are confirmed to show phased X-ray variations, then δ Cep will be the prototype of a new class of pulsation-induced X-ray variables.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhatwalia, Richa; Singh, Harkewal; Oppenheimer, Michelle

2015-10-15

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

X-ray ionization of the intergalactic medium by quasars

NASA Astrophysics Data System (ADS)

Graziani, Luca; Ciardi, B.; Glatzle, M.

2018-06-01

We investigate the impact of quasars on the ionization of the surrounding intergalactic medium (IGM) with the radiative transfer code CRASH4, now accounting for X-rays and secondary electrons. After comparing with analytic solutions, we post-process a cosmic volume (≈1.5 × 104 Mpc3h-3) containing a ULAS J1120+0641-like quasar (QSO) hosted by a 5 × 1011M⊙h-1 dark matter (DM) halo. We find that: (i) the average HII region (R ˜ 3.2 pMpc in a lifetime tf = 107 yrs) is mainly set by UV flux, in agreement with semi-analytic scaling relations; (ii) a largely neutral (xHII < 0.001), warm (T ˜ 103 K) tail extends up to few Mpc beyond the ionization front, as a result of the X-ray flux; (iii) LyC-opaque inhomogeneities induce a line of sight (LOS) scatter in R as high as few physical Mpc, consistent with the DLA scenario proposed to explain the anomalous size of the ULAS J1120+0641 ionized region. On the other hand, with an ionization rate \\dot{N}_{γ ,0} ˜ 10^{57} s-1, the assumed DLA clustering and gas opacity, only one LOS shows an HII region compatible with the observed one. We deduce that either the ionization rate of the QSO is at least one order of magnitude lower or the ULAS J1120+0641 bright phase is shorter than 107 yrs.

Aging-Induced Transformations of Maraging-400 Alloys

NASA Astrophysics Data System (ADS)

Alves, T. J. B.; Nunes, G. C. S.; Tupan, L. F. S.; Sarvezuk, P. W. C.; Ivashita, F. F.; de Oliveira, C. A. S.; Paesano, A.

2018-06-01

Solubilized maraging-400 alloys were aged at 480 °C, 580 °C, and 650 °C, for 3, 6, and 12 hours and characterized by X-ray diffraction (Rietveld refinement), Mössbauer spectroscopy, and microhardness tests. The results revealed that the aging treatments induced an atomic rearrangement in the martensite phase, involving a change in the composition and lattice parameters, reversion of austenite, and, in some samples, the formation of the μ phase. The amounts of reverted and precipitated phases were dependent on the aging time and temperature. The tetragonal distortion from cubic symmetry, usually presented by martensite in solution-annealed maraging steels, was not eliminated after aging. The results obtained for these maraging-400 alloys are compared with those obtained for maraging-350 steel samples.

Evolution of irradiation-induced strain in an equiatomic NiFe alloy

DOE PAGES

Ullah, Mohammad W.; Zhang, Yanwen; Sellami, Neila; ...

2017-07-10

Here, we investigate the formation and accumulation of irradiation-induced atomic strain in an equiatomic NiFe concentrated solid-solution alloy using both atomistic simulations and x-ray diffraction (XRD) analysis of irradiated samples. Experimentally, the irradiations are performed using 1.5 MeV Ni ions to fluences ranging from 1 × 10 13 to 1 × 10 14 cm -2. The irradiation simulations are carried out by overlapping 5 keV Ni recoils cascades up to a total of 300 recoils. An increase of volumetric strain is observed at low dose, which is associated with production of point defects and small clusters. A relaxation of strainmore » occurs at higher doses, when large defect clusters, like dislocation loops, dominate.« less

Particle Induced X-Ray Emission experiment using the K150 3.6 MeV proton beam at TAMU Cyclotron Institute

NASA Astrophysics Data System (ADS)

Pajouhafsar, Yasmin; Alis Manso Rodriguez Team; Sherry Yennello Team

2017-09-01

Particle Induced X-Ray Emission (PIXE) is a non-destructive analytical technique that is used for various tasks, such as elemental composition. The x-rays are emitted when electrons transition from higher to lower energy levels, causing vacancies in the atom's electron configuration. The overall goals of this research are to successfully set up a PIXE experiment and to obtain elemental concentrations for various samples, using the K150 proton beam in the Cyclotron Institute at Texas A&M University. The x-rays produced are unique to each element and analyzed with reference to their known energies. The setup consists of 3 different detectors, providing a wide range of energies: XR-100T CdTe γ/X-Ray, XR-100T/CR Si and XR-100SDD. Accelerating 3.6 MeV protons from the K150 and using PIXE, we determine concentrations from the NaCl samples provided by the Chemical Engineering Department. The concentrations for each element found in the NaCl thin films are obtained and analyzed through the software, GUPIXWIN. DOE Grant (DE-FG02-93ER40773) and Welch Foundation (A-1266).

Synchrotron Radiation Damage Mechanism of X-Ray Mask Membranes Irradiated in Helium Environment

NASA Astrophysics Data System (ADS)

Arakawa, Tomiyuki; Okuyama, Hiroshi; Okada, Koichi; Nagasawa, Hiroyuki; Syoki, Tsutomu; Yamaguchi, Yoh-ichi

1992-12-01

The mechanism of X-ray mask membrane displacement induced by synchrotron radiation (SR) has been discussed. Silicon nitride (SiN) and silicon carbide (SiC) membranes were irradiated by SR in a 1 atm helium ambient. SR-induced displacement for both membranes was 25-97 nm (σ). Oxygen concentration in both SiN and SiC was below 0.01 in O/Si atomic ratio. Although an increase in dangling bond density of SiN was observed, no remarkable increase in spin density was detected in SiC. Moreover, the most important finding was that thin oxides were grown on the membrane surface after SR irradiation. From these results, it is considered that the oxide growth on SiC membrane surfaces, and both the oxide growth and the increase of dangling bond density in SiN play an important role in the SR-induced displacement for the X-ray mask membranes.

Use of different spectroscopic techniques in the analysis of Roman age wall paintings.

PubMed

Agnoli, Francesca; Calliari, Irene; Mazzocchin, Gian-Antonio

2007-01-01

In this paper the analysis of samples of Roman age wall paintings coming from: Pordenone, Vicenza and Verona is carried out by using three different techniques: energy dispersive x-rays spectroscopy (EDS), x-rays fluorescence (XRF) and proton induced x-rays emission (PIXE). The features of the three spectroscopic techniques in the analysis of samples of archaeological interest are discussed. The studied pigments were: cinnabar, yellow ochre, green earth, Egyptian blue and carbon black.

Increase in recombination rate in Arabidopsis thaliana plants sharing gaseous environment with X-ray and UVC-irradiated plants depends on production of radicals.

PubMed

Zemp, Franz J; Sidler, Corinne; Kovalchuk, Igor

2012-07-01

X-ray and UVC are the two physical agents that damage DNA directly, with both agents capable of inducing double-strand breaks. Some of our recent work has demonstrated that local exposure to UVC results in a systemic increase in recombination frequency, suggesting that information about exposure can be passed from damaged to non-damaged tissue. Indeed, we recently showed that plants sharing the same enclosed environment with UVC-irradiated plants exhibit similar increase in homologous recombination frequency as irradiated plants. Here, we further tested whether yet another DNA-damaging agent, X-ray, is capable of increasing recombination rate (RR) in neighboring plants grown in a Petri dish. To test this, we grew plants exposed to X-ray or UVC irradiation in an enclosed environment next to non-exposed plants. We found that both X-ray and UVC-irradiated plants and neighboring plants exhibited comparable increases in the levels of strand breaks and the RR. We further showed that pre-exposure of plants to radical scavenger DMSO substantially alleviates the radiation-induced increase in RR and prevents formation of bystander signal. Our results suggest that the increase in RR in bystander plants can also be triggered by X-ray and that radicals may play some role in initiation or maintenance of this signal.

Increase in recombination rate in Arabidopsis thaliana plants sharing gaseous environment with X-ray and UVC-irradiated plants depends on production of radicals

PubMed Central

Zemp, Franz J.; Sidler, Corinne; Kovalchuk, Igor

2012-01-01

X-ray and UVC are the two physical agents that damage DNA directly, with both agents capable of inducing double-strand breaks. Some of our recent work has demonstrated that local exposure to UVC results in a systemic increase in recombination frequency, suggesting that information about exposure can be passed from damaged to non-damaged tissue. Indeed, we recently showed that plants sharing the same enclosed environment with UVC-irradiated plants exhibit similar increase in homologous recombination frequency as irradiated plants. Here, we further tested whether yet another DNA-damaging agent, X-ray, is capable of increasing recombination rate (RR) in neighboring plants grown in a Petri dish. To test this, we grew plants exposed to X-ray or UVC irradiation in an enclosed environment next to non-exposed plants. We found that both X-ray and UVC-irradiated plants and neighboring plants exhibited comparable increases in the levels of strand breaks and the RR. We further showed that pre-exposure of plants to radical scavenger DMSO substantially alleviates the radiation-induced increase in RR and prevents formation of bystander signal. Our results suggest that the increase in RR in bystander plants can also be triggered by X-ray and that radicals may play some role in initiation or maintenance of this signal. PMID:22751301

The rate of X-ray-induced DNA double-strand break repair in the embryonic mouse brain is unaffected by exposure to 50 Hz magnetic fields.

PubMed

Woodbine, Lisa; Haines, Jackie; Coster, Margaret; Barazzuol, Lara; Ainsbury, Elizabeth; Sienkiewicz, Zenon; Jeggo, Penny

2015-06-01

Following in utero exposure to low dose radiation (10-200 mGy), we recently observed a linear induction of DNA double-strand breaks (DSB) and activation of apoptosis in the embryonic neuronal stem/progenitor cell compartment. No significant induction of DSB or apoptosis was observed following exposure to magnetic fields (MF). In the present study, we exploited this in vivo system to examine whether exposure to MF before and after exposure to 100 mGy X-rays impacts upon DSB repair rates. 53BP1 foci were quantified following combined exposure to radiation and MF in the embryonic neuronal stem/progenitor cell compartment. Embryos were exposed in utero to 50 Hz MF at 300 μT for 3 h before and up to 9 h after exposure to 100 mGy X-rays. Controls included embryos exposed to MF or X-rays alone plus sham exposures. Exposure to MF before and after 100 mGy X-rays did not impact upon the rate of DSB repair in the embryonic neuronal stem cell compartment compared to repair rates following radiation exposure alone. We conclude that in this sensitive system MF do not exert any significant level of DNA damage and do not impede the repair of X-ray induced damage.

Multifractal Analysis of Seismically Induced Soft-Sediment Deformation Structures Imaged by X-Ray Computed Tomography

NASA Astrophysics Data System (ADS)

Nakashima, Yoshito; Komatsubara, Junko

Unconsolidated soft sediments deform and mix complexly by seismically induced fluidization. Such geological soft-sediment deformation structures (SSDSs) recorded in boring cores were imaged by X-ray computed tomography (CT), which enables visualization of the inhomogeneous spatial distribution of iron-bearing mineral grains as strong X-ray absorbers in the deformed strata. Multifractal analysis was applied to the two-dimensional (2D) CT images with various degrees of deformation and mixing. The results show that the distribution of the iron-bearing mineral grains is multifractal for less deformed/mixed strata and almost monofractal for fully mixed (i.e. almost homogenized) strata. Computer simulations of deformation of real and synthetic digital images were performed using the egg-beater flow model. The simulations successfully reproduced the transformation from the multifractal spectra into almost monofractal spectra (i.e. almost convergence on a single point) with an increase in deformation/mixing intensity. The present study demonstrates that multifractal analysis coupled with X-ray CT and the mixing flow model is useful to quantify the complexity of seismically induced SSDSs, standing as a novel method for the evaluation of cores for seismic risk assessment.

TH-AB-209-08: Next Generation Dedicated 3D Breast Imaging with XACT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, S; Chen, J; Samant, P

Purpose: Exposure to radiation increases the risk of cancer. We have designed a new imaging paradigm, X-ray induced acoustic computed tomography (XACT). Applying this innovative technology to breast imaging, an X-ray exposure can generate a 3D acoustic image, which dramatically reduces the radiation dose to patients when compared to conventional breast CT. Methods: Theoretical calculations are done to determine the appropriate X-ray energy and ultrasound frequency in breast XACT imaging. A series of breast CT image along the coronal plane from a patient with calcifications in the breast tissue are used as the source image. HU value based segmentation ismore » done to distinguish the skin, adipose tissue, glandular tissue, breast calcification, and chest bone from each CT image. X-ray dose deposition in each pixel is calculated based on the tissue type by using GEANT4 Monte Carlo toolkits. The initial pressure rise caused by X-ray energy deposition is calculated according to tissue properties. Then, the X-ray induced acoustic wave propagation is simulated by K-WAVE toolkit. Breast XACT images are reconstructed from the recorded time-dependent ultrasound waves. Results: For imaging a breast with large size (16cm in diameter at chest wall), the photon energy of X-ray source and the central frequency of ultrasound detector is determined as 20keV and 5.5MHz. Approximately 10 times contrast between a calcification and the breast tissue can be acquire from XACT image. The calcification can be clearly identified from the reconstructed XACT image. Conclusion: XACT technique takes the advantages of X-ray absorption contrast and high ultrasonic resolution. With the proposed innovative technology, one can potentially reduce radiation dose to patient in 3D breast imaging as compared with current x-ray modalities, while still maintaining high imaging contrast and spatial resolution.« less

Depth Profile of Induced Magnetic Polarization in Cu Layers of Co/Cu(111) Metallic Superlattices by Resonant X-ray Magnetic Scattering at the Cu K Absorption Edge

NASA Astrophysics Data System (ADS)

Uegaki, Shin; Yoshida, Akihiro; Hosoito, Nobuyoshi

2015-03-01

We investigated induced spin polarization of 4p conduction electrons in Cu layers of antiferromagnetically (AFM) and ferromagnetically (FM) coupled Co/Cu(111) metallic superlattices by resonant X-ray magnetic scattering at the Cu K absorption edge. Magnetic reflectivity profiles of the two superlattices were measured in the magnetic saturation state with circularly polarized synchrotron radiation X-rays at 8985 eV. Depth profiles of the resonant magnetic scattering length of Cu, which corresponds to the induced spin polarization of Cu, were evaluated in the two Co/Cu superlattices by analyzing the observed magnetic reflectivity profiles. We demonstrated that the spin polarization induced in the Cu layer was distributed around the Co/Cu interfaces with an attenuation length of several Å in both AFM and FM coupled superlattices. The uniform component, which exists in Au layers of Fe/Au(001) superlattices, was not found in the depth distribution of induced magnetic polarization in the Cu layers of Co/Cu(111) superlattices.

5f delocalization-induced suppression of quadrupolar order in U(Pd 1-xPt x)₃

DOE PAGES

Walker, H. C.; Le, M. D.; McEwen, K. A.; ...

2011-12-27

We present bulk magnetic and transport measurements and x-ray resonant scattering measurements on U(Pd 1-xPt x)₃ for x=0.005 and 0.01, which demonstrate the high sensitivity of the quadrupolar order in the canonical antiferroquadrupolar ordered system UPd₃ to doping with platinum. Bulk measurements for x=0.005 reveal behavior similar to that seen in UPd₃, albeit at a lower temperature, and x-ray resonant scattering provides evidence of quadrupolar order described by the Q xy order parameter. In contrast, bulk measurements reveal only an indistinct transition in x=0.01, consistent with the observation of short-range quadrupolar order in our x-ray resonant scattering results.

Improving Patient Safety with X-Ray and Anesthesia Machine Ventilator Synchronization: A Medical Device Interoperability Case Study

NASA Astrophysics Data System (ADS)

Arney, David; Goldman, Julian M.; Whitehead, Susan F.; Lee, Insup

When a x-ray image is needed during surgery, clinicians may stop the anesthesia machine ventilator while the exposure is made. If the ventilator is not restarted promptly, the patient may experience severe complications. This paper explores the interconnection of a ventilator and simulated x-ray into a prototype plug-and-play medical device system. This work assists ongoing interoperability framework development standards efforts to develop functional and non-functional requirements and illustrates the potential patient safety benefits of interoperable medical device systems by implementing a solution to a clinical use case requiring interoperability.

Better Ceramics Through Chemistry IV. Materials Research Society Sumposium Proceedings. Volume 180

DTIC Science & Technology

1991-03-31

GELS 117 L.F. Nazar, D.G. Napier, D. Lapham, and E. Epperson SMALL ANGLE X - RAY SCATTERING STUDIES Or POLYMERIC ZIRCONIUM SPECIES IN AQUEOUS SOLUTION...recently obtained the first X - ray crystallographic data on bismuth alkoxides, Bi(OR) 3 (R = C(CH3) 3 and C6 H4 (CH 3 )2 -2,6) [8]. These data showed that...d8, ppm): 12.5 (O2CMe), 9.6 (OCMe3). The complex was identified by X - ray crystallography. 1 crystallizes in space group P21/n with a = 13.149(2) A, b

High level tritiated water monitoring by Bremsstrahlung counting using a silicon drift detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niemes, S.; Sturm, M.; Michling, R.

2015-03-15

The β-ray induced X-ray spectrometry (BIXS) is a promising technique to monitor the tritium concentration in a fuel cycle of a fusion reactor. For in-situ measurements of high level tritiated water by Bremsstrahlung counting, the characteristics of a low-noise silicon drift detector (SDD) have been examined at the Tritium Laboratory Karlsruhe (TLK). In static measurements with constant sample volume and tritium concentration, the Bremsstrahlung spectra of tritiated water samples in a concentration range of 0.02 to 15 MBq/ml have been obtained. The volume has been kept constant at 5 cm{sup 3}. The observed spectra are well above the noise threshold.more » In addition to X-rays induced by β-rays, the spectra feature X-ray fluorescence peaks of the surrounding materials. No indications of memory effects have been observed. A linear relation between the X-ray intensity and the tritium concentration was obtained and the lower detection limit of the setup has been determined to 1 MBq ml{sup -1}, assessed by the Curie criterion. In addition, the spectra obtained experimentally could be reproduced with high agreement by Monte-Carlo simulations using the GEANT4-tool-kit. It was found that the present detection system is applicable to non-invasive measurements of high-level tritiated water and the SDD is a convenient tool to detect the low energy Bremsstrahlung X-rays. (authors)« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenik, E.A.

X-ray microanalysis in an analytical electron microscope is a proven technique for the measurement of solute segregation in alloys. Solute segregation under equilibrium or nonequilibrium conditions can strongly influence material performance. X-ray microanalysis in an analytical electron microscope provides an alternative technique to measure grain boundary segregation, as well as segregation to other defects not accessible to Auger analysis. The utility of the technique is demonstrated by measurements of equilibrium segregation to boundaries in an antimony containing stainless steel, including the variation of segregation with boundary character and by measurements of nonequilibrium segregation to boundaries and dislocations in an ion-irradiatedmore » stainless steel.« less

Effect of thermomechanical processing on the microstructure and retained austenite stability during in situ tensile testing using synchrotron x-ray diffraction of NbMoAI TRIP steel.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pereloma, E.; Zhang, L.; Liss, K.-D.

2011-06-01

In this work we compare and contrast the stability of retained austenite during tensile testing of Nb-Mo-Al transformation-induced plasticity steel subjected to different thermomechanical processing schedules. The obtained microstructures were characterised using optical metallography, transmission electron microscopy and X-ray diffraction. The transformation of retained austenite to martensite under tensile loading was observed by in-situ high energy X-ray diffraction at 1ID / APS. It has been shown that the variations in the microstructure of the steel, such as volume fractions of present phases, their morphology and dimensions, play a critical role in the strain-induced transition of retained austenite to martensite.

Polynuclear Speciation of Trivalent Cations near the Surface of an Electrolyte Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bera, Mrinal K.; Antonio, Mark R.

Despite long-standing efforts, there is no agreed upon structural model for electrolyte solutions at air-liquid interfaces. We report the simultaneous detection of the near-surface and bulk coordination environments of a trivalent metal cation (europium) in an aqueous solution by use of X-ray absorption spectroscopy. Within the first few nanometers of the liquid surface, the cations exhibit oxygen coordination typical of inner-sphere hydration of an aquated Eu3+ cation. Beyond that, outer-sphere ion-ion correlations are observed that are otherwise not present in the bulk electrolyte. The combination of near-surface and bulk sensitivities to probe metal ion speciation in electrolyte solutions is achievedmore » by detecting electron-yield and X-ray fluorescence signals from an inverted pendant drop. The results provide new knowledge about the near-surface chemistry of aqueous solutions of relevance to aerosols and ion transport processes in chemical separations and biological systems.« less

Removal of selected pharmaceuticals from aqueous solution using magnetic chitosan: sorption behavior and mechanism.

PubMed

Zhang, Yalei; Shen, Zhe; Dai, Chaomeng; Zhou, Xuefei

2014-11-01

A novel-modified magnetic chitosan adsorbent was used to remove selected pharmaceuticals, i.e., diclofenac (DCF) and clofibric acid (CA) and carbamazepine (CBZ), from aqueous solutions. The characterization of magnetic chitosan was achieved by scanning electron and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, vibrating sample magnetometer, and nitrogen sorption analysis. The magnetic chitosan had effective sorption affinity for DCF and CA but no sorption of CBZ was observed. The sorption capacities of CA and DCF in the individual solutions were 191.2 and 57.5 mg/g, respectively. While in mixed solution, DCF showed higher sorption affinity. Sorption kinetics indicated a quick equilibrium reached within 2 min. Lower solution pH values were found to be advantageous for the adsorption process. The sorption efficacy of CA declined significantly with increasing inorganic salt concentration. However, sorption performance of DCF was stable under different ionic strength conditions.

Synthesis and dc electrical conductivity of Cr-doped CeO2 nanoparticles by solution combustion method

NASA Astrophysics Data System (ADS)

Harish, B. M.; Avinash, B. S.; Chaturmukha, V. S.; Jayanna, H. S.; Suresh, S.; Naveen, C. S.; Lamani, Ashok R.

2018-04-01

NPs of Ce1-xCrxO2 (x=0, 0.04, 0.08, 0.12) have been synthesized by solution combustion method using glycine as fuel. The effect of chromium on structural and dc electrical conductivity of cerium oxide nanoparticles were investigated. The obtained powder is characterized by UV-visible spectrometer, X-ray diffractometer (XRD), Scanning electron microscope (SEM) and Energy dispersive X-Ray analysis (EDS). X-ray diffraction analysis carried out on calcined samples reveals that successful incorporation of Cr2+ in CeO2 lattice where as SEM studies confirms the porous morphological structure of the prepared sample. The Keithley source meter is used to measure the dc conductivity of samples in the temperature range from 303K to 623K. The conductivity was found to be increases with increase of temperature as well as the Cr concentration due to semiconducting behavior of material and change in the charge carrier concentration. The activation energy decreases with increasing chromium concentration. The present work deals with the effect of chromium additive on structural and the D.C electrical properties Ce1-xCrxO2 NPs.

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

PubMed

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.

Syntheses, Characterizations, and Applications of Molecular Metal Wires

DTIC Science & Technology

2011-08-05

treated with KPF6 (500 mg, 2.7 mmol). A dark greenish-brown complex was obtained after evaporation. The single crystals suitable for X-ray diffraction...CH2Cl2. Recrystallization from a CH2Cl2 solution layered with hexane gave deep brown single crystals suitable for X-ray diffraction. Yield: 83 mg...5 Synthetic challenges Conductance of single molecules Concluding Remarks

Origin of Pressure-induced Superconducting Phase in KxFe2-ySe2 studied by Synchrotron X-ray Diffraction and Spectroscopy

NASA Astrophysics Data System (ADS)

Yamamoto, Yoshiya; Yamaoka, Hitoshi; Tanaka, Masashi; Okazaki, Hiroyuki; Ozaki, Toshinori; Takano, Yoshihiko; Lin, Jung-Fu; Fujita, Hidenori; Kagayama, Tomoko; Shimizu, Katsuya; Hiraoka, Nozomu; Ishii, Hirofumi; Liao, Yen-Fa; Tsuei, Ku-Ding; Mizuki, Jun'Ichiro

2016-08-01

Pressure dependence of the electronic and crystal structures of KxFe2-ySe2, which has pressure-induced two superconducting domes of SC I and SC II, was investigated by x-ray emission spectroscopy and diffraction. X-ray diffraction data show that compressibility along the c-axis changes around 12 GPa, where a new superconducting phase of SC II appears. This suggests a possible tetragonal to collapsed tetragonal phase transition. X-ray emission spectroscopy data also shows the change in the electronic structure around 12 GPa. These results can be explained by the scenario that the two SC domes under pressure originate from the change of Fermi surface topology. Our results here show the pronounced increase of the density of states near the Fermi surface under pressure with a structural phase transition, which can help address our fundamental understanding for the appearance of the SC II phase.

Measurement of Lα and Lβ1,3,4 fluorescence cross sections of La, Ce, Pr and Nd induced by photons of energies between 7.01 keV and 8.75 keV

NASA Astrophysics Data System (ADS)

Reyes-Herrera, J.; Miranda, J.

2016-06-01

This study presents measurement results of x-ray production cross sections of Lα and Lβ1,3,4 emitted by four lanthanoid elements (La, Ce, Pr and Nd), after irradiation with Kα and Kβ X rays of the elements Co, Ni, Cu, and Zn (covering energies between 7.01 keV and 8.75 keV). Primary x-rays were induced in turn by the irradiation of thick targets of these elements with a beam of x-rays produced by a tube with an Rh anode, operating at 50 kV and 850 μA. The experimental results are compared with theoretical cross sections predicted using known tabulations of photoelectric cross sections. Dirac-Hartree-Slater (DHS) atomic parameters were used for these calculations. An acceptable match between experiment and both sets of tabulated data is found.

Ultra high-speed x-ray imaging of laser-driven shock compression using synchrotron light

NASA Astrophysics Data System (ADS)

Olbinado, Margie P.; Cantelli, Valentina; Mathon, Olivier; Pascarelli, Sakura; Grenzer, Joerg; Pelka, Alexander; Roedel, Melanie; Prencipe, Irene; Laso Garcia, Alejandro; Helbig, Uwe; Kraus, Dominik; Schramm, Ulrich; Cowan, Tom; Scheel, Mario; Pradel, Pierre; De Resseguier, Thibaut; Rack, Alexander

2018-02-01

A high-power, nanosecond pulsed laser impacting the surface of a material can generate an ablation plasma that drives a shock wave into it; while in situ x-ray imaging can provide a time-resolved probe of the shock-induced material behaviour on macroscopic length scales. Here, we report on an investigation into laser-driven shock compression of a polyurethane foam and a graphite rod by means of single-pulse synchrotron x-ray phase-contrast imaging with MHz frame rate. A 6 J, 10 ns pulsed laser was used to generate shock compression. Physical processes governing the laser-induced dynamic response such as elastic compression, compaction, pore collapse, fracture, and fragmentation have been imaged; and the advantage of exploiting the partial spatial coherence of a synchrotron source for studying low-density, carbon-based materials is emphasized. The successful combination of a high-energy laser and ultra high-speed x-ray imaging using synchrotron light demonstrates the potentiality of accessing complementary information from scientific studies of laser-driven shock compression.

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

PubMed Central

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

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

PubMed

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.

Lessons learned in the execution of advanced x-ray material discrimination (Conference Presentation)

NASA Astrophysics Data System (ADS)

Young, Sharene

2017-05-01

Advanced X-ray Material Discrimination (AXMD) or BAA 13-05 was a broad agency announcement which was initiated in order to develop solutions to the following problem. The emergence of improvised explosive threats and their use by terrorists has placed many challenges on the aviation security screening layers. EDS and AT X-ray equipment have been presented with considerable challenges in developing a broad detection capability for improvised explosive threats during security screening of checked bags and carry-on items. Technologies are needed that increase the measurement or mathematical discrimination between improvised explosive threats and stream-of-commerce clutter in checked baggage and carry-on items. Conventional EDS utilizes two basic discriminating signatures: effective atomic number and density of screened objects. R and D is needed to identify additional discriminating signatures between improvised explosive threats and stream-of commerce clutter to improve detection capability with reduced false alarm rates. DHS S and T EXD along with stakeholders at the TSA, TSL, and the UK Home Office have been successful in funding efforts to address and potentially provide operational solutions which can be deployed as part of the Next Generation of X-ray Technologies.

Hydrothermal Diamond Anvil Cell (HDAC): From Visual Observation to X-ray Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Bassett, W. A.; Mibe, K.

2006-05-01

A fluid sample contained in a Re gasket between two diamond anvils can be subjected to pressures up to 2.5 GPa and temperatures up to 1200°C in a resistively heated hydrothermal diamond anvil cell (HDAC). Thermocouples are used to measure temperature. The constant-volume sample chamber permits isochoric measurements that can be used to determine pressure from the equation of state of H2O and to map phases and properties in P-T space. A movie of reactions between K-feldspar and water up to 2.5 GPa and 880°C illustrates the use of visual observations for mapping coexisting solution, melt, and solid phases. X-ray absorption spectroscopy of ZnBr2 in solution up to 500°C and 500 MPa shows hydrogen bond breaking in the hydration shells of the ZnBr42- and Br- ions with increasing temperature. In other studies the stability field of ikaite (CaCO3·6H2O) has been mapped by visual observation and Raman spectroscopy; the phases of montmorillonite have been mapped by X-ray diffraction; and the leaching of Pb from zircon has been measured by X-ray microprobe.

Real-Time X-Ray Transmission Microscopy of Solidifying Al-In Alloys

NASA Technical Reports Server (NTRS)

Curreri, Peter A.; Kaukler, William F.

1997-01-01

Real-time observations of transparent analog materials have provided insight, yet the results of these observations are not necessarily representative of opaque metallic systems. In order to study the detailed dynamics of the solidification process, we develop the technologies needed for real-time X ray microscopy of solidifying metallic systems, which has not previously been feasible with the necessary resolution, speed, and contrast. In initial studies of Al-In monotectic alloys unidirectionally solidified in an X-ray transparent furnace, in situ records of the evolution of interface morphologies, interfacial solute accumulation, and formation of the monotectic droplets were obtained for the first time: A radiomicrograph of Al-30In grown during aircraft parabolic maneuvers is presented, showing the volumetric phase distribution in this specimen. The benefits of using X-ray microscopy for postsolidification metallography include ease of specimen preparation, increased sensitivity, and three-dimensional analysis of phase distribution. Imaging of the solute boundary layer revealed that the isoconcentration lines are not parallel (as is often assumed) to the growth interface. Striations in the solidified crystal did not accurately decorate the interface position and shape. The monotectic composition alloy under some conditions grew in an uncoupled manner.

Mutation induction in haploid yeast after split-dose radiation exposure. II. Combination of UV-irradiation and X-rays.

PubMed

Keller, B; Zölzer, F; Kiefer, J

2004-01-01

Split-dose protocols can be used to investigate the kinetics of recovery from radiation damage and to elucidate the mechanisms of cell inactivation and mutation induction. In this study, a haploid strain of the yeast, Saccharomyces cerevisiae, wild-type with regard to radiation sensitivity, was irradiated with 254-nm ultraviolet (UV) light and then exposed to X-rays after incubation for 0-6 hr. The cells were incubated either on nutrient medium or salt agar between the treatments. Loss of reproductive ability and mutation to canavanine resistance were measured. When the X-ray exposure immediately followed UV-irradiation, the X-ray survival curves had the same slope irrespective of the pretreatment, while the X-ray mutation induction curves were changed from linear to linear quadratic with increasing UV fluence. Incubations up to about 3 hr on nutrient medium between the treatments led to synergism with respect to cell inactivation and antagonism with respect to mutation, but after 4-6 hr the two treatments acted independently. Incubation on salt agar did not cause any change in the survival curves, but there was a strong suppression of X-ray-induced mutation with increasing UV fluence. On the basis of these results, we suggest that mutation after combined UV and X-ray exposure is affected not only by the induction and suppression of DNA repair processes, but also by radiation-induced modifications of cell-cycle progression and changes in the expression of the mutant phenotype. Copyright 2004 Wiley-Liss, Inc.

Field-induced antiferroelectric to ferroelectric transitions in (Pb 1–xLa x)(Zr 0.90Ti 0.10) 1–x/ 4O 3 investigated by in situ X-ray diffraction

DOE PAGES

Ciuchi, Ioana V.; Chung, Ching -Chang; Fancher, Christopher M.; ...

2017-06-17

Phase transitions and field-induced preferred orientation in (Pb 1-xLa x)(Zr 0.90Ti 0.10) 1–x/ 4O 3 (PLZT x/90/10) ceramics upon electric field cycling using in situ X-ray diffraction were studied. The evolution of the {200} pc and {111} pc diffraction line profiles indicate that PLZT 4/90/10 and PLZT 3/90/10 compositions undergo an antiferroelectric (AFE)–ferroelectric (FE) phase switching. Both PLZT 4/90/10 and PLZT 3/90/10 exhibit irreversible preferred orientation after experiencing the field-induced AFE-to-FE phase switching. An electric field-induced structure develops in both compositions which has a reversible character during the field decreasing in PLZT 4/90/10 and an irreversible character in PLZT 3/90/10.more » In addition, structural analysis of pre-poled PLZT 3/90/10 ceramics show that it is possible to induce consecutive FE-to-AFE and AFE-to-FE transitions when fields of reversed polarity are applied in sequence. The field range required to induce the AFE phase is broad, and the phase transition is kinetically slow. In conclusion, this kind of transition has rarely been reported before.« less

Field-induced antiferroelectric to ferroelectric transitions in (Pb 1–xLa x)(Zr 0.90Ti 0.10) 1–x/ 4O 3 investigated by in situ X-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciuchi, Ioana V.; Chung, Ching -Chang; Fancher, Christopher M.

Phase transitions and field-induced preferred orientation in (Pb 1-xLa x)(Zr 0.90Ti 0.10) 1–x/ 4O 3 (PLZT x/90/10) ceramics upon electric field cycling using in situ X-ray diffraction were studied. The evolution of the {200} pc and {111} pc diffraction line profiles indicate that PLZT 4/90/10 and PLZT 3/90/10 compositions undergo an antiferroelectric (AFE)–ferroelectric (FE) phase switching. Both PLZT 4/90/10 and PLZT 3/90/10 exhibit irreversible preferred orientation after experiencing the field-induced AFE-to-FE phase switching. An electric field-induced structure develops in both compositions which has a reversible character during the field decreasing in PLZT 4/90/10 and an irreversible character in PLZT 3/90/10.more » In addition, structural analysis of pre-poled PLZT 3/90/10 ceramics show that it is possible to induce consecutive FE-to-AFE and AFE-to-FE transitions when fields of reversed polarity are applied in sequence. The field range required to induce the AFE phase is broad, and the phase transition is kinetically slow. In conclusion, this kind of transition has rarely been reported before.« less

Energetics of a uranothorite (Th 1–xU xSiO 4) solid solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Xiaofeng; Szenknect, Stephanie; Mesbah, Adel

High-temperature oxide melt solution calorimetric measurements were completed to determine the enthalpies of formation of the uranothorite, (USiO 4) x–(ThSiO 4) 1–x, solid solution. Phase-pure samples with x values of 0, 0.11, 0.21, 0.35, 0.71, and 0.84 were prepared, purified, and characterized by powder X-ray diffraction, electron probe microanalysis, thermogravimetric analysis and differential scanning calorimetry coupled with in situ mass spectrometry, and high-temperature oxide melt solution calorimetry. This work confirms the energetic metastability of coffinite, USiO 4, and U-rich intermediate silicate phases with respect to a mixture of binary oxides. Furthermore, variations in unit cell parameters and negative excess volumesmore » of mixing, coupled with strongly exothermic enthalpies of mixing in the solid solution, suggest short-range cation ordering that can stabilize intermediate compositions, especially near x = 0.5.« less

Energetics of a uranothorite (Th 1–xU xSiO 4) solid solution

DOE PAGES

Guo, Xiaofeng; Szenknect, Stephanie; Mesbah, Adel; ...

2016-10-11

High-temperature oxide melt solution calorimetric measurements were completed to determine the enthalpies of formation of the uranothorite, (USiO 4) x–(ThSiO 4) 1–x, solid solution. Phase-pure samples with x values of 0, 0.11, 0.21, 0.35, 0.71, and 0.84 were prepared, purified, and characterized by powder X-ray diffraction, electron probe microanalysis, thermogravimetric analysis and differential scanning calorimetry coupled with in situ mass spectrometry, and high-temperature oxide melt solution calorimetry. This work confirms the energetic metastability of coffinite, USiO 4, and U-rich intermediate silicate phases with respect to a mixture of binary oxides. Furthermore, variations in unit cell parameters and negative excess volumesmore » of mixing, coupled with strongly exothermic enthalpies of mixing in the solid solution, suggest short-range cation ordering that can stabilize intermediate compositions, especially near x = 0.5.« less

Homogeneity study of a GaAs:Cr pixelated sensor by means of X-rays

NASA Astrophysics Data System (ADS)

Billoud, T.; Leroy, C.; Papadatos, C.; Pichotka, M.; Pospisil, S.; Roux, J. S.

2018-04-01

Direct conversion semiconductor detectors have become an indispensable tool in radiation detection by now. In order to obtain a high detection efficiency, especially when detecting X or γ rays, high-Z semiconductor sensors are necessary. Like other compound semiconductors GaAs, compensated by chromium (GaAs:Cr), suffers from a number of defects that affect the charge collection efficiency and homogeneity of the material. A precise knowledge of this problem is important to predict the performance of such detectors and eventually correct their response in specific applications. In this study we analyse the homogeneity and mobility-lifetime products (μe τe) of a 500 μ m thick GaAs:Cr pixelated sensor connected to a Timepix chip. The detector is irradiated by 23 keV X-rays, each pixel recording the number of photon interactions and the charge they induce on its electrode. The μe τe products are extracted on a per-pixel basis, using the Hecht equation corrected for the small pixel effect. The detector shows a good time stability in the experimental conditions. Significant inhomogeneities are observed in photon counting and charge collection efficiencies. An average μe τe of 1.0 ṡ 10‑4 cm2V‑1 is found, and compared with values obtained by other methods for the same material. Solutions to improve the response are discussed.

Investigations of interatomic interaction in InAs-InAs1-xSbx heterostructures on a base of x-ray diffractometry

NASA Astrophysics Data System (ADS)

Babjuck, T. I.; Buntar, A. G.; Shevtchuk, L. S.

2001-06-01

Hetero-transitions on a base of InAs and AnSb compounds permitted to obtain cheap light diodes and detectors with the atmosphere maximal transparency region sensibility. There is assumed simultaneously, that the phon radiation in InAs-InAs1-xSbx is not large, which positively effects on receiver parameters. Changing the composition of InAs-InAs1- xSbx solution, one may obtain the structure with the width of forbidden zone of the want of 0.35 to 0,1 eV. There is developed the heterostructures crystalline lattice parameters determining method (for substrate and film) with the DRON-3M x-ray diffractometer. There was found the nonlinear dependence of the heterostructures lattice parameter on the composition. Investigations of interatomic interaction in dependence on composition and also on the forbidden zone width Eg(x) have show, that solid solutions InAs-InAs1- xSbx may be used for the obtaining of infra-red receiver.

L-edge spectroscopy of dilute, radiation-sensitive systems using a transition-edge-sensor array

NASA Astrophysics Data System (ADS)

Titus, Charles J.; Baker, Michael L.; Lee, Sang Jun; Cho, Hsiao-Mei; Doriese, William B.; Fowler, Joseph W.; Gaffney, Kelly; Gard, Johnathon D.; Hilton, Gene C.; Kenney, Chris; Knight, Jason; Li, Dale; Marks, Ronald; Minitti, Michael P.; Morgan, Kelsey M.; O'Neil, Galen C.; Reintsema, Carl D.; Schmidt, Daniel R.; Sokaras, Dimosthenis; Swetz, Daniel S.; Ullom, Joel N.; Weng, Tsu-Chien; Williams, Christopher; Young, Betty A.; Irwin, Kent D.; Solomon, Edward I.; Nordlund, Dennis

2017-12-01

We present X-ray absorption spectroscopy and resonant inelastic X-ray scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous ferricyanide. These measurements demonstrate the ability of high-throughput transition-edge-sensor (TES) spectrometers to access the rich soft X-ray (100-2000 eV) spectroscopy regime for dilute and radiation-sensitive samples. Our low-concentration data are in agreement with high-concentration measurements recorded by grating spectrometers. These results show that soft-X-ray RIXS spectroscopy acquired by high-throughput TES spectrometers can be used to study the local electronic structure of dilute metal-centered complexes relevant to biology, chemistry, and catalysis. In particular, TES spectrometers have a unique ability to characterize frozen solutions of radiation- and temperature-sensitive samples.

Structure-based analysis reveals hydration changes induced by arginine hydrochloride.

PubMed

Nakakido, Makoto; Tanaka, Yoshikazu; Mitsuhori, Mariko; Kudou, Motonori; Ejima, Daisuke; Arakawa, Tsutomu; Tsumoto, Kouhei

2008-10-01

Arginine hydrochloride has been used to suppress protein aggregation during refolding and in various other applications. We investigated the structure of hen egg-white lysozyme (HEL) and solvent molecules in arginine hydrochloride solution by X-ray crystallography. Neither the backbone nor side-chain structure of HEL was altered by the presence of arginine hydrochloride. In addition, no stably bound arginine molecules were observed. The number of hydration water molecules, however, changed with the arginine hydrochloride concentration. We suggest that arginine hydrochloride suppresses protein aggregation by altering the hydration structure and the transient binding of arginine molecules that could not be observed.

Inter-DNA Attraction Mediated by Divalent Counterions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiu Xiangyun; Andresen, Kurt; Kwok, Lisa W.

2007-07-20

Can nonspecifically bound divalent counterions induce attraction between DNA strands? Here, we present experimental evidence demonstrating attraction between short DNA strands mediated by Mg{sup 2+} ions. Solution small angle x-ray scattering data collected as a function of DNA concentration enable model independent extraction of the second virial coefficient. As the [Mg{sup 2+}] increases, this coefficient turns from positive to negative reflecting the transition from repulsive to attractive inter-DNA interaction. This surprising observation is corroborated by independent light scattering experiments. The dependence of the observed attraction on experimental parameters including DNA length provides valuable clues to its origin.

Kinetic-limited etching of magnesium doping nitrogen polar GaN in potassium hydroxide solution

NASA Astrophysics Data System (ADS)

Jiang, Junyan; Zhang, Yuantao; Chi, Chen; Yang, Fan; Li, Pengchong; Zhao, Degang; Zhang, Baolin; Du, Guotong

2016-01-01

KOH based wet etchings were performed on both undoped and Mg-doped N-polar GaN films grown by metal-organic chemical vapor deposition. It is found that the etching rate for Mg-doped N-polar GaN gets slow obviously compared with undoped N-polar GaN. X-ray photoelectron spectroscopy analysis proved that Mg oxide formed on N-polar GaN surface is insoluble in KOH solution so that kinetic-limited etching occurs as the etching process goes on. The etching process model of Mg-doped N-polar GaN in KOH solution is tentatively purposed using a simplified ideal atomic configuration. Raman spectroscopy analysis reveals that Mg doping can induce tensile strain in N-polar GaN films. Meanwhile, p-type N-polar GaN film with a hole concentration of 2.4 ÿ 1017 cm⿿3 was obtained by optimizing bis-cyclopentadienyl magnesium flow rates.

A novel method for improving cerussite sulfidization

NASA Astrophysics Data System (ADS)

Feng, Qi-cheng; Wen, Shu-ming; Zhao, Wen-juan; Cao, Qin-bo; Lü, Chao

2016-06-01

Evaluation of flotation behavior, solution measurements, and surface analyses were performed to investigate the effects of chloride ion addition on the sulfidization of cerussite in this study. Micro-flotation tests indicate that the addition of chloride ions prior to sulfidization can significantly increase the flotation recovery of cerussite, which is attributed to the formation of more lead sulfide species on the mineral surface. Solution measurement results suggest that the addition of chloride ions prior to sulfidization induces the transformation of more sulfide ions from pulp solution onto the mineral surface by the formation of more lead sulfide species. X-ray diffraction and energy-dispersive spectroscopy indicate that more lead sulfide species form on the mineral surface when chloride ions are added prior to sulfidization. These results demonstrate that the addition of chloride ions prior to sulfidization can significantly improve the sulfidization of cerussite, thereby enhancing the flotation performance.

Thermally Induced Structural Evolution and Performance of Mesoporous Block Copolymer-Directed Alumina Perovskite Solar Cells

PubMed Central

2015-01-01

Structure control in solution-processed hybrid perovskites is crucial to design and fabricate highly efficient solar cells. Here, we utilize in situ grazing incidence wide-angle X-ray scattering and scanning electron microscopy to investigate the structural evolution and film morphologies of methylammonium lead tri-iodide/chloride (CH3NH3PbI3–xClx) in mesoporous block copolymer derived alumina superstructures during thermal annealing. We show the CH3NH3PbI3–xClx material evolution to be characterized by three distinct structures: a crystalline precursor structure not described previously, a 3D perovskite structure, and a mixture of compounds resulting from degradation. Finally, we demonstrate how understanding the processing parameters provides the foundation needed for optimal perovskite film morphology and coverage, leading to enhanced block copolymer-directed perovskite solar cell performance. PMID:24684494

Solvent minimization induces preferential orientation and crystal clustering in serial micro-crystallography on micro-meshes, in situ plates and on a movable crystal conveyor belt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soares, Alexei S.; Mullen, Jeffrey D.; Parekh, Ruchi M.

X-ray diffraction data were obtained at the National Synchrotron Light Source from insulin and lysozyme crystals that were densely deposited on three types of surfaces suitable for serial micro-crystallography: MiTeGen MicroMeshes™, Greiner Bio-One Ltdin situmicro-plates, and a moving kapton crystal conveyor belt that is used to deliver crystals directly into the X-ray beam. 6° wedges of data were taken from ~100 crystals mounted on each material, and these individual data sets were merged to form nine complete data sets (six from insulin crystals and three from lysozyme crystals). Insulin crystals have a parallelepiped habit with an extended flat face thatmore » preferentially aligned with the mounting surfaces, impacting the data collection strategy and the design of the serial crystallography apparatus. Lysozyme crystals had a cuboidal habit and showed no preferential orientation. Preferential orientation occluded regions of reciprocal space when the X-ray beam was incident normal to the data-collection medium surface, requiring a second pass of data collection with the apparatus inclined away from the orthogonal. In addition, crystals measuring less than 20 µm were observed to clump together into clusters of crystals. Clustering required that the X-ray beam be adjusted to match the crystal size to prevent overlapping diffraction patterns. No additional problems were encountered with the serial crystallography strategy of combining small randomly oriented wedges of data from a large number of specimens. Lastly, high-quality data able to support a realistic molecular replacement solution were readily obtained from both crystal types using all three serial crystallography strategies.« less

Solvent minimization induces preferential orientation and crystal clustering in serial micro-crystallography on micro-meshes, in situ plates and on a movable crystal conveyor belt.

PubMed

Soares, Alexei S; Mullen, Jeffrey D; Parekh, Ruchi M; McCarthy, Grace S; Roessler, Christian G; Jackimowicz, Rick; Skinner, John M; Orville, Allen M; Allaire, Marc; Sweet, Robert M

2014-11-01

X-ray diffraction data were obtained at the National Synchrotron Light Source from insulin and lysozyme crystals that were densely deposited on three types of surfaces suitable for serial micro-crystallography: MiTeGen MicroMeshes™, Greiner Bio-One Ltd in situ micro-plates, and a moving kapton crystal conveyor belt that is used to deliver crystals directly into the X-ray beam. 6° wedges of data were taken from ∼100 crystals mounted on each material, and these individual data sets were merged to form nine complete data sets (six from insulin crystals and three from lysozyme crystals). Insulin crystals have a parallelepiped habit with an extended flat face that preferentially aligned with the mounting surfaces, impacting the data collection strategy and the design of the serial crystallography apparatus. Lysozyme crystals had a cuboidal habit and showed no preferential orientation. Preferential orientation occluded regions of reciprocal space when the X-ray beam was incident normal to the data-collection medium surface, requiring a second pass of data collection with the apparatus inclined away from the orthogonal. In addition, crystals measuring less than 20 µm were observed to clump together into clusters of crystals. Clustering required that the X-ray beam be adjusted to match the crystal size to prevent overlapping diffraction patterns. No additional problems were encountered with the serial crystallography strategy of combining small randomly oriented wedges of data from a large number of specimens. High-quality data able to support a realistic molecular replacement solution were readily obtained from both crystal types using all three serial crystallography strategies.

Solvent minimization induces preferential orientation and crystal clustering in serial micro-crystallography on micro-meshes, in situ plates and on a movable crystal conveyor belt

DOE PAGES

Soares, Alexei S.; Mullen, Jeffrey D.; Parekh, Ruchi M.; ...

2014-10-09

X-ray diffraction data were obtained at the National Synchrotron Light Source from insulin and lysozyme crystals that were densely deposited on three types of surfaces suitable for serial micro-crystallography: MiTeGen MicroMeshes™, Greiner Bio-One Ltdin situmicro-plates, and a moving kapton crystal conveyor belt that is used to deliver crystals directly into the X-ray beam. 6° wedges of data were taken from ~100 crystals mounted on each material, and these individual data sets were merged to form nine complete data sets (six from insulin crystals and three from lysozyme crystals). Insulin crystals have a parallelepiped habit with an extended flat face thatmore » preferentially aligned with the mounting surfaces, impacting the data collection strategy and the design of the serial crystallography apparatus. Lysozyme crystals had a cuboidal habit and showed no preferential orientation. Preferential orientation occluded regions of reciprocal space when the X-ray beam was incident normal to the data-collection medium surface, requiring a second pass of data collection with the apparatus inclined away from the orthogonal. In addition, crystals measuring less than 20 µm were observed to clump together into clusters of crystals. Clustering required that the X-ray beam be adjusted to match the crystal size to prevent overlapping diffraction patterns. No additional problems were encountered with the serial crystallography strategy of combining small randomly oriented wedges of data from a large number of specimens. Lastly, high-quality data able to support a realistic molecular replacement solution were readily obtained from both crystal types using all three serial crystallography strategies.« less

Solvent minimization induces preferential orientation and crystal clustering in serial micro-crystallography on micro-meshes, in situ plates and on a movable crystal conveyor belt

PubMed Central

Soares, Alexei S.; Mullen, Jeffrey D.; Parekh, Ruchi M.; McCarthy, Grace S.; Roessler, Christian G.; Jackimowicz, Rick; Skinner, John M.; Orville, Allen M.; Allaire, Marc; Sweet, Robert M.

2014-01-01

X-ray diffraction data were obtained at the National Synchrotron Light Source from insulin and lysozyme crystals that were densely deposited on three types of surfaces suitable for serial micro-crystallography: MiTeGen MicroMeshes™, Greiner Bio-One Ltd in situ micro-plates, and a moving kapton crystal conveyor belt that is used to deliver crystals directly into the X-ray beam. 6° wedges of data were taken from ∼100 crystals mounted on each material, and these individual data sets were merged to form nine complete data sets (six from insulin crystals and three from lysozyme crystals). Insulin crystals have a parallelepiped habit with an extended flat face that preferentially aligned with the mounting surfaces, impacting the data collection strategy and the design of the serial crystallography apparatus. Lysozyme crystals had a cuboidal habit and showed no preferential orientation. Preferential orientation occluded regions of reciprocal space when the X-ray beam was incident normal to the data-collection medium surface, requiring a second pass of data collection with the apparatus inclined away from the orthogonal. In addition, crystals measuring less than 20 µm were observed to clump together into clusters of crystals. Clustering required that the X-ray beam be adjusted to match the crystal size to prevent overlapping diffraction patterns. No additional problems were encountered with the serial crystallography strategy of combining small randomly oriented wedges of data from a large number of specimens. High-quality data able to support a realistic molecular replacement solution were readily obtained from both crystal types using all three serial crystallography strategies. PMID:25343789

Structural characterization of metal complexes in aqueous solutions: a XAS study of stannous fluoride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alsina, Marco A.; Gaillard, Jean-François

The identity and structure of tin(ii)-fluoride complexes formed in aqueous solutions are determined by combining X-ray absorption spectroscopy, thermodynamic modeling and quantum mechanical calculations.

The structure investigations of dehydroacetic acid and 1,8-diaminonaphthalene condensation product by NMR, MS, and X-ray measurements

NASA Astrophysics Data System (ADS)

Kołodziej, B.; Morawiak, M.; Kamieński, B.; Schilf, W.

2016-05-01

A new unexpected product of condensation reaction of 1,8-diaminonaphthalene (DAN) and carbonyl compound (here: dehydroacetic acid (dha)) was synthesized. Discussion about the molecular structure of possible products of this reaction was done on the base of NMR studies. The structure of the titled product in both DMSO solution and in the solid state was resolved by analysis of its spectral data (X-ray structure analysis, multinuclear NMR in solution and solid state spectra) and MS measurements. The presented studies provided clear evidence that the titled product exists in diluted DMSO solution as the mixture of two kinetic free ionic species whereas in concentrated DMSO solution as well as in the solid state this system forms associated ionic pairs bonded together by hydrogen bonds.

Quantitative disentanglement of coherent and incoherent laser-induced surface deformations by time-resolved x-ray reflectivity

NASA Astrophysics Data System (ADS)

Sander, M.; Pudell, J.-E.; Herzog, M.; Bargheer, M.; Bauer, R.; Besse, V.; Temnov, V.; Gaal, P.

2017-12-01

We present time-resolved x-ray reflectivity measurements on laser excited coherent and incoherent surface deformations of thin metallic films. Based on a kinematical diffraction model, we derive the surface amplitude from the diffracted x-ray intensity and resolve transient surface excursions with sub-Å spatial precision and 70 ps temporal resolution. The analysis allows for decomposition of the surface amplitude into multiple coherent acoustic modes and a substantial contribution from incoherent phonons which constitute the sample heating.