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Sample records for synthesis x-ray structure

  1. Synthesis and X-ray structure of the dysprosium(III) complex derived ...

    African Journals Online (AJOL)

    Synthesis and X-ray structure of the dysprosium(III) complex derived from the ligand 5-chloro-1 ... Bulletin of the Chemical Society of Ethiopia ... synthesized and its crystal structure determined by single X-ray diffraction at room temperature.

  2. Synthesis, X-ray crystal structure, DNA binding and Nuclease activity ...

    Indian Academy of Sciences (India)

    s12039-016-1125-x. Synthesis, X-ray crystal structure, DNA binding and Nuclease activity of lanthanide(III) complexes of 2-benzoylpyridine acetylhydrazone. KARREDDULA RAJA, AKKILI SUSEELAMMA and KATREDDI HUSSAIN REDDY. ∗.

  3. Total chemical synthesis and X-ray structure of kaliotoxin by racemic protein crystallography.

    Science.gov (United States)

    Pentelute, Brad L; Mandal, Kalyaneswar; Gates, Zachary P; Sawaya, Michael R; Yeates, Todd O; Kent, Stephen B H

    2010-11-21

    Here we report the total synthesis of kaliotoxin by 'one pot' native chemical ligation of three synthetic peptides. A racemic mixture of D- and L-kaliotoxin synthetic protein molecules gave crystals in the centrosymmetric space group P1 that diffracted to atomic-resolution (0.95 Å), enabling the X-ray structure of kaliotoxin to be determined by direct methods.

  4. Synthesis, characterization, x-ray structure and antimicrobial activity ...

    African Journals Online (AJOL)

    intermolecular N3—H1N1•••O1 hydrogen bonds. (Table 2), resulting in the formation of zigzag layers lying parallel to (100) (Fig. 2b). The existence of π•••π interactions involving the centroid of the N4/C9-C13 pyridine ring (π•••π distance = 3.5108(18) Å) further stabilize the molecular packing. The structure of compound 2.

  5. Cell-free protein synthesis for structure determination by X-ray crystallography.

    Science.gov (United States)

    Watanabe, Miki; Miyazono, Ken-ichi; Tanokura, Masaru; Sawasaki, Tatsuya; Endo, Yaeta; Kobayashi, Ichizo

    2010-01-01

    Structure determination has been difficult for those proteins that are toxic to the cells and cannot be prepared in a large amount in vivo. These proteins, even when biologically very interesting, tend to be left uncharacterized in the structural genomics projects. Their cell-free synthesis can bypass the toxicity problem. Among the various cell-free systems, the wheat-germ-based system is of special interest due to the following points: (1) Because the gene is placed under a plant translational signal, its toxic expression in a bacterial host is reduced. (2) It has only little codon preference and, especially, little discrimination between methionine and selenomethionine (SeMet), which allows easy preparation of selenomethionylated proteins for crystal structure determination by SAD and MAD methods. (3) Translation is uncoupled from transcription, so that the toxicity of the translation product on DNA and its transcription, if any, can be bypassed. We have shown that the wheat-germ-based cell-free protein synthesis is useful for X-ray crystallography of one of the 4-bp cutter restriction enzymes, which are expected to be very toxic to all forms of cells retaining the genome. Our report on its structure represents the first report of structure determination by X-ray crystallography using protein overexpressed with the wheat-germ-based cell-free protein expression system. This will be a method of choice for cytotoxic proteins when its cost is not a problem. Its use will become popular when the crystal structure determination technology has evolved to require only a tiny amount of protein.

  6. Synthesis of hydroxyapatite and structural refinement by X-ray diffraction

    International Nuclear Information System (INIS)

    Araujo, Jorge Correa de

    2007-01-01

    A sample of hydroxyapatite was synthesized and its crystalline structure was analyzed by X-ray diffraction by means of the Rietveld method. Two functions were used to fit the peak profiles, modified Voigt (TCHZ) and Pearson VII. The occupational factors and lattice parameters obtained by both models show that the sample does not contain relevant cationic substitutions. The interatomic distances from Ca1 to oxygens O1, O2 and O3 were adequate for a pure hydroxyapatite without defect at site Ca1. Besides, the use of multiple lines in planes (300) and (002) associated with the model Pearson VII resulted in good agreement with the TCHZ model with respect to the size-strain effects with an ellipsoidal shape of crystallites. In conclusion, the procedures adopted in the synthesis of hydroxyapatite produced a pure and crystalline material. The experimental results of transmission electron microscopy confirmed the predicted shape of crystals. (author)

  7. Synthesis, X-ray crystal structure and theoretical calculations of antileishmanial neolignan analogues

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Josenaide P. do; Santos, Lourivaldo S.; Carmo, Maria Carolina L. do; Brasil, Davi S.B.; Alves, Claudio N., E-mail: nahum@ufpa.b [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Inst. de Ciencias Exatas e Naturais; Santos, Regina Helena A.; Tozzo, Erica; Ferreira, Janaina G. [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil). Inst. de Quimica

    2010-07-01

    The synthesis and X-ray crystal diffraction structure of two analogues of neolignans, 2-(4-chlorophenyl)-1-phenylethanone (20) and 2-[(4-chlorophenyl)thio]-1-(3,4-dimethoxyphenyl) propan-1-one (12) is described. The compound 12 presents activity against intracellular Leishmania donovani and Leishmania amazonensis amastigotes that cause cutaneous and visceral leishmaniasis. In addition, the density functional theory (DFT) with the B3LYP hybrid functional was employed to calculate a set of molecular descriptors for nineteen synthetic analogues of neolignans with antileishmanial activities. Afterwards, the stepwise discriminant analysis was performed to investigate possible relationship between the molecular descriptors and biological activities. Through this analysis the compounds were classified into two groups active and inactive according to their degree of biological activities, and the more important properties were charges on some key atoms, electronic affinity and ClogP. (author)

  8. Synthesis, X-ray crystal structure and theoretical calculations of antileishmanial neolignan analogues

    International Nuclear Information System (INIS)

    Nascimento, Josenaide P. do; Santos, Lourivaldo S.; Carmo, Maria Carolina L. do; Brasil, Davi S.B.; Alves, Claudio N.; Santos, Regina Helena A.; Tozzo, Erica; Ferreira, Janaina G.

    2010-01-01

    The synthesis and X-ray crystal diffraction structure of two analogues of neolignans, 2-(4-chlorophenyl)-1-phenylethanone (20) and 2-[(4-chlorophenyl)thio]-1-(3,4-dimethoxyphenyl) propan-1-one (12) is described. The compound 12 presents activity against intracellular Leishmania donovani and Leishmania amazonensis amastigotes that cause cutaneous and visceral leishmaniasis. In addition, the density functional theory (DFT) with the B3LYP hybrid functional was employed to calculate a set of molecular descriptors for nineteen synthetic analogues of neolignans with antileishmanial activities. Afterwards, the stepwise discriminant analysis was performed to investigate possible relationship between the molecular descriptors and biological activities. Through this analysis the compounds were classified into two groups active and inactive according to their degree of biological activities, and the more important properties were charges on some key atoms, electronic affinity and ClogP. (author)

  9. Tin( ii ) ketoacidoximates: synthesis, X-ray structures and processing to tin( ii ) oxide

    KAUST Repository

    Khanderi, Jayaprakash

    2015-10-21

    Tin(ii) ketoacidoximates of the type [HONCRCOO]Sn (R = Me 1, CHPh 2) and (MeONCMeCOO)Sn] NH·2HO 3 were synthesized by reacting pyruvate- and hydroxyl- or methoxylamine RONH (R = H, Me) with tin(ii) chloride dihydrate SnCl·2HO. The single crystal X-ray structure reveals that the geometry at the Sn atom is trigonal bipyramidal in 1, 2 and trigonal pyramidal in 3. Inter- or intramolecular hydrogen bonding is observed in 1-3. Thermogravimetric (TG) analysis shows that the decomposition of 1-3 to SnO occurs at ca. 160 °C. The evolved gas analysis during TG indicates complete loss of the oximato ligand in one step for 1 whereas a small organic residue is additionally removed at temperatures >400 °C for 2. Above 140 °C, [HONC(Me)COO]Sn (1) decomposes in air to spherical SnO particles of size 10-500 nm. Spin coating of 1 on Si or a glass substrate followed by heating at 200 °C results in a uniform film of SnO. The band gap of the produced SnO film and nanomaterial was determined by diffuse reflectance spectroscopy to be in the range of 3.0-3.3 eV. X-ray photoelectron spectroscopy indicates surface oxidation of the SnO film to SnO in ambient atmosphere.

  10. Synthesis, X-ray structure determination and germination studies on some smoke-derived karrikins

    Czech Academy of Sciences Publication Activity Database

    Nair, J. J.; Pošta, Martin; Papenfus, H. B.; Munro, O. Q.; Beier, Petr; van Staden, J.

    2014-01-01

    Roč. 91, Mar (2014), s. 53-57 ISSN 0254-6299 Institutional support: RVO:61388963 Keywords : germination * karrikin * plant growth regulator * smoke * X-ray Subject RIV: CC - Organic Chemistry Impact factor: 0.978, year: 2014

  11. Synthesis, X-ray Structure, Spectroscopic Properties and DFT Studies of a Novel Schiff Base

    Directory of Open Access Journals (Sweden)

    Kew-Yu Chen

    2014-10-01

    Full Text Available A series of Schiff bases, salicylideneaniline derivatives 1–4, was synthesized under mild conditions and characterized by 1H NMR, HRMS, UV-Vis and fluorescence spectra, and single-crystal X-ray diffraction. In solid and aprotic solvents 1–4 exist mainly as E conformers that possess an intramolecular six-membered-ring hydrogen bond. A weak intramolecular C–H×××F hydrogen bond is also observed in fluoro-functionalized Schiff base 4, which generates another S(6 ring motif. The C–H×××F hydrogen bond further stabilizes its structure and leads it to form a planar configuration. Compounds 1–3 exhibit solely a long-wavelength proton-transfer tautomer emission, while dipole-functionalized Schiff base 4 shows remarkable dual emission originated from the excited-state intramolecular charge transfer (ESICT and excited-state intramolecular proton transfer (ESIPT states. Furthermore, the geometric structures, frontier molecular orbitals (MOs and the potential energy curves for 1–4 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT and time-dependent DFT calculations.

  12. Synthesis, X-ray Structure, Optical, and Electrochemical Properties of a White-Light-Emitting Molecule

    Directory of Open Access Journals (Sweden)

    Jiun-Wei Hu

    2016-01-01

    Full Text Available A new white-light-emitting molecule (1 was synthesized and characterized by NMR spectroscopy, high resolution mass spectrometry, and single-crystal X-ray diffraction. Compound 1 crystallizes in the orthorhombic space group Pnma, with a = 12.6814(6, b = 7.0824(4, c = 17.4628(9 Å, α = 90°, β = 90°, γ = 90°. In the crystal, molecules are linked by weak intermolecular C-H···O hydrogen bonds, forming an infinite chain along [100], generating a C(10 motif. Compound 1 possesses an intramolecular six-membered-ring hydrogen bond, from which excited-state intramolecular proton transfer (ESIPT takes place from the phenolic proton to the carbonyl oxygen, resulting in a tautomer that is in equilibrium with the normal species, exhibiting a dual emission that covers almost all of the visible spectrum and consequently generates white light. It exhibits one irreversible one-electron oxidation and two irreversible one-electron reductions in dichloromethane at modest potentials. Furthermore, the geometric structures, frontier molecular orbitals (MOs, and the potential energy curves (PECs for 1 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT and time-dependent DFT calculations. The results demonstrate that the forward and backward ESIPT may happen on a similar timescale, enabling the excited-state equilibrium to be established.

  13. Chromium(III) Complex Obtained from Dipicolinic Acid: Synthesis, Characterization, X-Ray Crystal Structure and Electrochemical Studies

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi, Khaled; Rezvani, Ali Reza; Ghasemi, Fatemeh [Univ. of Sistan and Baluchestan, Zahedan (Iran, Islamic Republic of); Razak, Ibrahim Abdul; Rosli, Mohd Mustaqim [Universiti Sains Malaysia, Penang (Malaysia)

    2013-10-15

    The synthesis, X-ray crystallography, spectroscopic (IR, UV-vis), and electrochemical properties of the title compound, [H{sub 3}O][Cr(dipic){sub 2}] [H{sub 3}O{sup +}.Cl{sup -}] (1), (H{sub 2}dipic = 2,6-pyridinedicarboxylic acid), are reported. This complex crystallizes in the monoclinic space group Cc with a = 14.9006(10) A, b = 12.2114(8) A, c = 8.6337(6) A, α = 90.00 .deg., β = 92.7460(10) .deg., γ = 90.00 .deg., and V = 1569.16(18) A3 with Z = 4. The hydrogen bonding and noncovalent interactions play roles in the stabilization of the structure. In order to gain a better understanding of the most important geometrical parameters in the structure of the complex, atoms in molecules (AIM) method at B3LYP/6-31G level of theory has been employed.

  14. Proof of the Structure of the Stemodia chilensis Tetracyclic Diterpenoid (+)-19-Acetoxystemodan-12-ol by Synthesis from (+)-Podocarpic Acid: X-ray Structure Determination of a Key Intermediate.

    Science.gov (United States)

    Leonelli, Francesca; Mostarda, Azzurra; De Angelis, Luca; Lamba, Doriano; Demitri, Nicola; La Bella, Angela; Ceccacci, Francesca; Migneco, Luisa M; Marini Bettolo, Rinaldo

    2016-04-22

    The first synthesis of (+)-19-acetoxystemodan-12-ol (1), a stemodane diterpenoid isolated from Stemodia chilensis, is described. The structure was supported by an X-ray crystallographic analysis of intermediate (+)-9a, which confirmed the proposed structure and excluded the structure of (-)-19-hydroxystemod-12-ene as a possible candidate for the Chilean Calceolaria diterpenoid to which the (-)-19-hydroxystemar-13-ene structure (9b) had been erroneously assigned.

  15. Synthesis, quantum chemical computations and x-ray ...

    African Journals Online (AJOL)

    Benyza N

    2017-05-01

    May 1, 2017 ... manganese (+II) co-ordination with pyridine-2,6-dicarboxamide oxime. We report here the synthesis, the single crystal X-ray structure of the complex and the Optimization of the structure using ... Absorption coefficient (mm. -1. ).

  16. Fully convergent chemical synthesis of ester insulin: determination of the high resolution X-ray structure by racemic protein crystallography.

    Science.gov (United States)

    Avital-Shmilovici, Michal; Mandal, Kalyaneswar; Gates, Zachary P; Phillips, Nelson B; Weiss, Michael A; Kent, Stephen B H

    2013-02-27

    Efficient total synthesis of insulin is important to enable the application of medicinal chemistry to the optimization of the properties of this important protein molecule. Recently we described "ester insulin"--a novel form of insulin in which the function of the 35 residue C-peptide of proinsulin is replaced by a single covalent bond--as a key intermediate for the efficient total synthesis of insulin. Here we describe a fully convergent synthetic route to the ester insulin molecule from three unprotected peptide segments of approximately equal size. The synthetic ester insulin polypeptide chain folded much more rapidly than proinsulin, and at physiological pH. Both the D-protein and L-protein enantiomers of monomeric DKP ester insulin (i.e., [Asp(B10), Lys(B28), Pro(B29)]ester insulin) were prepared by total chemical synthesis. The atomic structure of the synthetic ester insulin molecule was determined by racemic protein X-ray crystallography to a resolution of 1.6 Å. Diffraction quality crystals were readily obtained from the racemic mixture of {D-DKP ester insulin + L-DKP ester insulin}, whereas crystals were not obtained from the L-ester insulin alone even after extensive trials. Both the D-protein and L-protein enantiomers of monomeric DKP ester insulin were assayed for receptor binding and in diabetic rats, before and after conversion by saponification to the corresponding DKP insulin enantiomers. L-DKP ester insulin bound weakly to the insulin receptor, while synthetic L-DKP insulin derived from the L-DKP ester insulin intermediate was fully active in binding to the insulin receptor. The D- and L-DKP ester insulins and D-DKP insulin were inactive in lowering blood glucose in diabetic rats, while synthetic L-DKP insulin was fully active in this biological assay. The structural basis of the lack of biological activity of ester insulin is discussed.

  17. Synthesis and Single Crystal X-Ray Structure Determination of 3,3',5 ...

    African Journals Online (AJOL)

    Single crystal structure determination at 100 K revealed needle-like crystals in an orthorhombic crystal system. The asymmetric unit of the cell consists of an isolated chloride ion, one half of a tetrahedral [MnCl4]2- anion, a [H2Me4bpz]2+ dication and one half of a molecule of water. Keywords: Crystal Engineering, Hydrogen ...

  18. X-ray metrology for ULSI structures

    International Nuclear Information System (INIS)

    Bowen, D. K.; Matney, K. M.; Wormington, M.

    1998-01-01

    Non-destructive X-ray metrological methods are discussed for application to both process development and process control of ULSI structures. X-ray methods can (a) detect the unacceptable levels of internal defects generated by RTA processes in large wafers, (b) accurately measure the thickness and roughness of layers between 1 and 1000 nm thick and (c) can monitor parameters such as crystallographic texture and the roughness of buried interfaces. In this paper we review transmission X-ray topography, thin film texture measurement, grazing-incidence X-ray reflectivity and high-resolution X-ray diffraction. We discuss in particular their suitability as on-line sensors for process control

  19. Synthesis and X-Ray Crystal Structures of Mononuclear Complexes of 1,3-Bis(8-quinolyloxy)propane

    International Nuclear Information System (INIS)

    Al-Mandhary, M.R.; Steel, P.

    2002-01-01

    The preparations and X-ray crystal structures of the first transition metal complexes of 1,3-bis(8-quinolyloxy)propane are described. The ligand acts as a trans-chelating N,N'-bidentate ligand in the three-coordinate silver nitrate complex and four-coordinate copper chloride complex, but as an N,O,O',N'-tetradentate ligand in the octahedral nickel chloride complex. Copyright (2002) CSIRO Australia

  20. Synthesis of 1 nm Pd Nanoparticles in a Microfluidic Reactor: Insights from in Situ X ray Absorption Fine Structure Spectroscopy and Small-Angle X ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Karim, Ayman M.; Al Hasan, Naila M.; Ivanov, Sergei A.; Siefert, Soenke; Kelly, Ryan T.; Hallfors, Nicholas G.; Benavidez, Angelica D.; Kovarik, Libor; Jenkins, Aaron; Winans, R. E.; Datye, Abhaya K.

    2015-06-11

    In this paper we show that the temporal separation of nucleation and growth is not a necessary condition for the colloidal synthesis of monodisperse nanoparticles. The synthesis mechanism of Pd nanoparticles was determined by in situ XAFS and SAXS in a microfluidic reactor capable of millisecond up to an hour time resolution. The SAXS results showed two autocatalytic growth phases, a fast growth phase followed by a very slow growth phase. The steady increase in the number of particles throughout the two growth phases indicates the synthesis is limited by slow continuous nucleation. The transition from fast to slow growth was caused by rapid increase in bonding with the capping agent as shown by XAFS. Based on this fundamental understanding of the synthesis mechanism, we show that 1 nm monodisperse Pd nanoparticles can be synthesized at low temperature using a strong binding capping agent such as trioctylphosphine (TOP).

  1. Comparison of two binuclear vanadium-catecholate complexes: Synthesis, X-ray structure and effects in cancer cells

    Science.gov (United States)

    Chi, Zixiang; Zhu, Linli; Lu, Xiaoming

    2011-08-01

    Two binuclear vanadium-catecholate complexes [Et 3NH] 2[V VO 2(μ-cat)] 2( 1) and [Et 3NH] 2[V VO 2(μ-N-2,3-D)] 2( 2) (cat = catechol, N-2,3-D = naphthalene-2,3-diol) have been synthesized and characterized by X-ray diffraction, IR, UV-vis spectroscopy and cyclic voltammetry (CV). X-ray analysis reveals that the structures of complexes 1 and 2 are both in the anion form of V. Et 3N works as counter-ions and connects the main frame by hydrogen bonding. The electrochemical behavior of the two complexes is studied in comparison to that of the free ligands and the two complexes display different redox potentials. Pharmaceutical screenings of complexes 1 and 2 have been made against two representative cancer cell-lines A-549 (lung cancer) and Bel-7402 (liver cancer) by MTT assay. The inhibition of cell proliferation was determined 72 h after cells were exposed to the tested compounds at a concentration of 5 μg/mL. Complex 1 exhibits well inhibition ratio against both two cell-lines (76.28% and 75.94%), while 2 displays positive and negative effect (65.36% and -68.82%) respectively. In association with X-ray and electrochemistry, a preliminary analysis about the possible inhibitory mechanism is provided.

  2. Carboranyl tetrahydroisoquinolines. Synthesis and the X-ray structural study of 1-(o-Carboran-1-ylmethyl)-1,2,3,4-Tetrahydroisoquinolines

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Dae; Kang, Sang Ook [Korea University, Dept. of Chemistry, Chung-nam (Korea); Lee, Chai-Ho [Wonkwang Univ., Dept. of Chemistry, Jeonbuk (Korea); Lee, Seung-Hoon [National Cancer Center, Kyungi-do (Korea); Lim, Sang-Moo [Korea Cancer Center Hospital, Seoul (Korea); Cho, Sungil [Seoul City Univ., Dept. of Chemical Engineering, Seoul (Korea)

    2001-11-01

    Synthesis of the first fully characterized boronated tetrahydroisoquinolines is reported. Thus, tetrahydroisoquinolines containing 1-(0-carboran-1-ylmethyl)-1,2,3,4-tetrahydroisoquinolines have been synthesized from the corresponding arylethylamines to provide carboranes attached to functional group capable of being covalently incorporated into structures of potential use in boron neutron capture therapy (BNCT). The carboranyl functionalities were attached at the 1-position of the tetrahydroisoquinoline molecule. Experimental details and analytical data leading to the identification of the reported compounds are provided. Additionally, the X-ray diffraction structure of 9b is reported. (author)

  3. Synthesis, X-ray crystal structure and optical properties research of novel diphenyl sulfone-based bis-pyrazoline derivatives

    International Nuclear Information System (INIS)

    Gong Zhongliang; Zheng Liangwen; Zhao Baoxiang

    2012-01-01

    A series of novel bis-pyrazoline derivatives were synthesized by the reaction of chalcone and (sulfonylbis(3,1-phenylene))bis(hydrazine) in 20–34% yields. The structures of the compounds were determined by IR, 1 H NMR, HRMS spectra, and a representative compound 3b was confirmed based on the X-ray crystallographic analysis. Absorption and fluorescence spectra of these compounds in dichloromethane solution were investigated. The results showed that the emission maxima varied from 415 to 444 nm mainly depending on C3 substituents of pyrazoline moiety. The compounds had higher quantum yields, when C3 substituent was an electron-withdrawing p-chlorophenyl group. Moreover, absorption spectra and emission spectra exhibited a blue-shift and a red-shift with increasing the polarity of solvents, respectively. Fluorescent molecules happened to collide with each other and resulted in quench of the fluorescence when the concentration increased over to 10 −5 M. - Highlights: ► A series of novel diphenyl sulfone-based bis-pyrazoline derivatives were designed and synthesized. ► Their UV–vis absorption and fluorescence emission spectra were investigated. ► The relationship of substituents and the optical properties were discussed. ► With increasing the solvent polarity, fluorescence emission displayed a red-shift and fluorescence quantum yields decreased. ► Fluorescence was quenched when the concentration increased over to 10 −5 M.

  4. Cadmium (II) macrocyclic Schiff-base complexes containing piperazine moiety: Synthesis, spectroscopic, X-ray structure, theoretical and antibacterial studies

    Science.gov (United States)

    Keypour, Hassan; Mahmoudabadi, Masoumeh; Shooshtari, Amir; Bayat, Mehdi; Mohsenzadeh, Fariba; Gable, Robert William

    2018-03-01

    The new Cd(II) macrocyclic Schiff-base complexes were prepared via the metal templated [1 + 1] cyclocondensation of 2,2'-(piperazine-1,4-diylbis (methylene))dianiline (A) and 2,6-pyridinedicarbaldehyde or 2,6-diacetylpyridine. The products were characterized by elemental analysis, mass spectrometry and spectroscopic methods such as: FT-IR, 1H and 13C-NMR, the crystal structure of [CdL1(ClO4)2](CH3CN) (1) complex was also obtained by single-crystal X-ray crystallography. The complexes were tested for in vitro antibacterial properties against some bacteria. The complexes had antibacterial properties and in some cases were active even more than standards. The geometries of the [CdLn (ClO4)2], (n = 1,2) complexes have been optimized at the BP86/def2-SVP level of theory. Also the nature of Cd←Ln (n = 1, 2) bonds in [CdLn (ClO4)2], (n = 1,2) complexes are studied with the help of NBO and Energy decomposition analysis (EDA). Results showed that the nature of metal-ligand bond in the complexes is slightly more electrostatic with a contribution of about 52% in total interaction energy.

  5. Severe Acute Respiratory Syndrome-Coronavirus Papain-Like Novel Protease Inhibitors: Design, Synthesis, Protein-Ligand X-ray Structure and Biological Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Arun K.; Takayama, Jun; Rao, Kalapala Venkateswar; Ratia, Kiira; Chaudhuri, Rima; Mulhearn, Debbie C.; Lee, Hyun; Nichols, Daniel B.; Baliji, Surendranath; Baker, Susan C.; Johnson, Michael E.; Mesecar, Andrew D. (Purdue); (UC); (UIC)

    2012-02-21

    The design, synthesis, X-ray crystal structure, molecular modeling, and biological evaluation of a series of new generation SARS-CoV PLpro inhibitors are described. A new lead compound 3 (6577871) was identified via high-throughput screening of a diverse chemical library. Subsequently, we carried out lead optimization and structure-activity studies to provide a series of improved inhibitors that show potent PLpro inhibition and antiviral activity against SARS-CoV infected Vero E6 cells. Interestingly, the (S)-Me inhibitor 15h (enzyme IC{sub 50} = 0.56 {mu}M; antiviral EC{sub 50} = 9.1 {mu}M) and the corresponding (R)-Me 15g (IC{sub 50} = 0.32 {mu}M; antiviral EC{sub 50} = 9.1 {mu}M) are the most potent compounds in this series, with nearly equivalent enzymatic inhibition and antiviral activity. A protein-ligand X-ray structure of 15g-bound SARS-CoV PLpro and a corresponding model of 15h docked to PLpro provide intriguing molecular insight into the ligand-binding site interactions.

  6. Determination of the X-ray structure of the snake venom protein omwaprin by total chemical synthesis and racemic protein crystallography.

    Science.gov (United States)

    Banigan, James R; Mandal, Kalyaneswar; Sawaya, Michael R; Thammavongsa, Vilasak; Hendrickx, Antoni P A; Schneewind, Olaf; Yeates, Todd O; Kent, Stephen B H

    2010-10-01

    The 50-residue snake venom protein L-omwaprin and its enantiomer D-omwaprin were prepared by total chemical synthesis. Radial diffusion assays were performed against Bacillus megaterium and Bacillus anthracis; both L- and D-omwaprin showed antibacterial activity against B. megaterium. The native protein enantiomer, made of L-amino acids, failed to crystallize readily. However, when a racemic mixture containing equal amounts of L- and D-omwaprin was used, diffraction quality crystals were obtained. The racemic protein sample crystallized in the centrosymmetric space group P2(1)/c and its structure was determined at atomic resolution (1.33 A) by a combination of Patterson and direct methods based on the strong scattering from the sulfur atoms in the eight cysteine residues per protein. Racemic crystallography once again proved to be a valuable method for obtaining crystals of recalcitrant proteins and for determining high-resolution X-ray structures by direct methods.

  7. Synthesis, structural, X-ray photoelectron spectroscopy (XPS) studies and IR induced anisotropy of Tl{sub 4}HgI{sub 6} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Parasyuk, O.V. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, Voli Ave. 13, Lutsk, 43025 (Ukraine); Khyzhun, O.Y. [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky St., 03142, Kyiv (Ukraine); Piasecki, M. [Institute of Physics, J. Dlugosz University Częstochowa, Armii Krajowej 13/15, Częstochowa (Poland); Kityk, I.V., E-mail: iwank74@gmail.com [Electrical Engineering Department, Czestochowa University Technology, Armii Krajowej 17, PL-42-217, Czestochowa (Poland); Lakshminarayana, G. [Wireless and Photonic Networks Research Centre, Faculty of Engineering, Universiti Putra Malaysia, 43400, Serdang, Selangor (Malaysia); Luzhnyi, I. [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky St., 03142, Kyiv (Ukraine); Fochuk, P.M. [Yuriy Fed’kovych Chernivtsi National University, 2 Kotziubynskoho Str., 58012, Chernivtsi (Ukraine); Fedorchuk, A.O. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, Pekarska Street 50, 79010, Lviv (Ukraine); Levkovets, S.I.; Yurchenko, O.M.; Piskach, L.V. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, Voli Ave. 13, Lutsk, 43025 (Ukraine)

    2017-02-01

    In the present work, we report on the synthesis and structural properties including X-ray protoelectron spectroscopy (XPS) analysis of Tl{sub 4}HgI{sub 6} crystals that were grown by Bridgman-Stockbarger method up to 80 mm in length and 18 mm in diameter. The existence of the ternary compound Tl{sub 4}HgI{sub 6} that melts incongruently at 641 K was confirmed. Phase equilibria and structural properties for the TlI–HgI{sub 2} system were investigated by differential thermal analysis (DTA) and X-ray diffraction (XRD) methods. X-ray photoelectron spectra were measured for both pristine and Ar{sup +} ion-bombarded Tl{sub 4}HgI{sub 6} single crystal surfaces. The data reveal that the Tl{sub 4}HgI{sub 6} single crystal is sensitive with respect to Ar{sup +} ion-bombardment as 3.0 keV Ar{sup +} irradiation over 5 min at an ion current density 14 μA/cm{sup 2} induces changes to the elemental stoichiometry of the Tl{sub 4}HgI{sub 6} surface, leading to a decrease of the mercury content in the topmost surface layers. X-ray photoelectron spectroscopy (XPS) measurements indicate very low hygroscopic nature of the Tl{sub 4}HgI{sub 6} single crystal surface. The IR coherent bicolor laser treatment at wavelengths 10.6/5.3 μm has shown an occurrence of anisotropy at wavelengths 1540 nm of Er:glass laser. This may open the applications of Tl{sub 4}HgI{sub 6} as a material for IR laser triggering. - Highlights: • Phase diagram of the HgI{sub 2}–TlI system was built. • Tl{sub 4}HgI{sub 6} single crystals were grown by Bridgman Stockbarger method. • XRD, XPS analysis was done. • Ir induced anisotropy was established. • The compounds may be proposed as Ir laser operated polarizers.

  8. Synthesis of hydroxyapatite and structural refinement by X-ray diffraction; Sintese da hidroxiapatita e refinamento estrutural por difracao de raios-X

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Jorge Correa de [Universidade do Estado do Rio de Janeiro (UERJ), Sao Goncalo, RJ (Brazil). Faculdade de Formacao de Professores; Sena, Lidia [Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial (INMETRO), Duque de Caxias, RJ (Brazil). Div. de Metrologia de Materiais; Bastos, Ivan Napoleao [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Inst. Politecnico]. E-mail: jcaraujo@iprj.uerj.br; Soares, Gloria Dulce de Almeida [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)

    2007-07-01

    A sample of hydroxyapatite was synthesized and its crystalline structure was analyzed by X-ray diffraction by means of the Rietveld method. Two functions were used to fit the peak profiles, modified Voigt (TCHZ) and Pearson VII. The occupational factors and lattice parameters obtained by both models show that the sample does not contain relevant cationic substitutions. The interatomic distances from Ca1 to oxygens O1, O2 and O3 were adequate for a pure hydroxyapatite without defect at site Ca1. Besides, the use of multiple lines in planes (300) and (002) associated with the model Pearson VII resulted in good agreement with the TCHZ model with respect to the size-strain effects with an ellipsoidal shape of crystallites. In conclusion, the procedures adopted in the synthesis of hydroxyapatite produced a pure and crystalline material. The experimental results of transmission electron microscopy confirmed the predicted shape of crystals. (author)

  9. Structure determination by X-ray crystallography

    CERN Document Server

    Ladd, M F C

    1995-01-01

    X-ray crystallography provides us with the most accurate picture we can get of atomic and molecular structures in crystals. It provides a hard bedrock of structural results in chemistry and in mineralogy. In biology, where the structures are not fully crystalline, it can still provide valuable results and, indeed, the impact here has been revolutionary. It is still an immense field for young workers, and no doubt will provide yet more striking develop­ ments of a major character. It does, however, require a wide range of intellectual application, and a considerable ability in many fields. This book will provide much help. It is a very straightforward and thorough guide to every aspect of the subject. The authors are experienced both as research workers themselves and as teachers of standing, and this is shown in their clarity of exposition. There are plenty of iliustrations and worked examples to aid the student to obtain a real grasp of the subject.

  10. Wavelength dispersive X-ray absorption fine structure imaging by parametric X-ray radiation

    International Nuclear Information System (INIS)

    Inagaki, Manabu; Sakai, Takeshi; Sato, Isamu; Hayakawa, Yasushi; Nogami, Kyoko; Tanaka, Toshinari; Hayakawa, Ken; Nakao, Keisuke

    2008-01-01

    The parametric X-ray radiation (PXR) generator system at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University is a monochromatic and coherent X-ray source with horizontal wavelength dispersion. The energy definition of the X-rays, which depends on the horizontal size of the incident electron beam on the generator target crystal, has been investigated experimentally by measuring the X-ray absorption near edge structure (XANES) spectra on Cu and CuO associated with conventional X-ray absorption imaging technique. The result demonstrated the controllability of the spectrum resolution of XANES by adjusting of the horizontal electron beam size on the target crystal. The XANES spectra were obtained with energy resolution of several eV at the narrowest case, which is in qualitative agreement with the energy definition of the PXR X-rays evaluated from geometrical consideration. The result also suggested that the wavelength dispersive X-ray absorption fine structure measurement associated with imaging technique is one of the promising applications of PXR. (author)

  11. Synchrotron x-ray fluorescence and extended x-ray absorption fine structure analysis

    International Nuclear Information System (INIS)

    Chen, J.R.; Gordon, B.M.; Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Chao, E.C.T.; Minkin, J.A.

    1984-01-01

    The advent of dedicated synchrotron radiation sources has led to a significant increase in activity in many areas of science dealing with the interaction of x-rays with matter. Synchrotron radiation provides intense, linearly polarized, naturally collimated, continuously tunable photon beams, which are used to determine not only the elemental composition of a complex, polyatomic, dilute material but also the chemical form of the elements with improved accuracy. Examples of the application of synchrotron radiation include experiments in synchrotron x-ray fluorescence (SXRF) analysis and extended x-ray absorption fine structure (EXAFS) analysis. New synchrotron radiation x-ray microprobes for elemental analysis in the parts per billion range are under construction at several laboratories. 76 references, 24 figures

  12. Multiscale structural study using scanning X-ray microscope

    International Nuclear Information System (INIS)

    Ohsumi, Hiroyuki; Arima, Taka-hisa

    2016-01-01

    Correspondence between structures at the atomic- and meso-scales can be given by scanning X-ray microscopy integrated with polarized X-ray diffractometry. Symmetry is the common structural feature available across multiple hierarchies. This article introduces a symmetry evaluation technique based on polarized X-ray diffractometry and describes two embodiments: chirality domain observation and antiferromagnetic domain observation. Multiscale structural studies would play an important role in uncovering universality of hierarchical structure. (author)

  13. Synthesis and structure elucidation of a series of pyranochromene chalcones and flavanones using 1D and 2D NMR spectroscopy and X-ray crystallography.

    Science.gov (United States)

    Pawar, Sunayna S; Koorbanally, Neil A

    2014-06-01

    A series of novel pyranochromene chalcones and corresponding flavanones were synthesized. This is the first report on the confirmation of the absolute configuration of chromene-based flavanones using X-ray crystallography. These compounds were characterized by 2D NMR spectroscopy, and their assignments are reported herein. The 3D structure of the chalcone 3b and flavanone 4g was determined by X-ray crystallography, and the structure of the flavanone was confirmed to be in the S configuration at C-2. Copyright © 2014 John Wiley & Sons, Ltd.

  14. Structure determination by X-ray crystallography

    CERN Document Server

    Ladd, M F C

    1977-01-01

    Crystallography may be described as the science of the structure of materi­ als, using this word in its widest sense, and its ramifications are apparent over a broad front of current scientific endeavor. It is not surprising, therefore, to find that most universities offer some aspects of crystallography in their undergraduate courses in the physical sciences. It is the principal aim of this book to present an introduction to structure determination by X-ray crystal­ lography that is appropriate mainly to both final-year undergraduate studies in crystallography, chemistry, and chemical physics, and introductory post­ graduate work in this area of crystallography. We believe that the book will be of interest in other disciplines, such as physics, metallurgy, biochemistry, and geology, where crystallography has an important part to play. In the space of one book, it is not possible either to cover all aspects of crystallography or to treat all the subject matter completely rigorously. In particular, certain ...

  15. Synthesis and X-ray crystal structure of the first tetrathiafulvalene-based acceptor-donor-acceptor sandwich

    DEFF Research Database (Denmark)

    Simonsen, Klaus B.; Thorup, Niels; Cava, Michael P.

    1998-01-01

    The synthesis and characterization of a bis-macrocyclic A-D-A sandwich produced in a simple one-pot reaction is reported. Only one acceptor unit participates in charge-transfer interactions with the TTF unit in the solid state....

  16. Spectroscopic studies, theoretical models and structural characterization. II. Synthesis and X-ray powder diffraction of the elpasolites Cs2NaSmCl6

    International Nuclear Information System (INIS)

    Poblete, V.; Acevedo, R.

    1998-01-01

    In this research work, we report the synthesis and structural characterization of the stoichiometric elpasolite Cs 2 NaSmCl 6 . The synthesis was performed under a solid state reaction in nitrogen atmosphere from the chemicals CsCl, NaCl and SmCl 3 weighted stoichiometrically. The best possible crystallization temperature was obtained using thermal studies of the type DTA/TGA (the thermal treatment was allowed to proceed for 2.5 hours at 755 Centigrade, showing a temperature gradient of 10 Centigrade/minute). The structural characterization by powder X-ray diffraction (XDR) indicates that this elpasolite belongs to the Fm 3m (O h 5 ) space group and the optimized structural parameters are as follows: a 0 = 10.8342 Armstrong, V 1271.72 Armstrong 3 , Z=4, M=651.88, D x =3.406 y D exp=3.41 ± 0.01. The profile refinement, using the Rietveld method, allowed us to fit the experimental and the calculated intensities of a total of 32 lines. The above result indicates that the condition R exp 2+ + 3Cl -1 and the counter ions filling the octahedral holes, in full agreement with anti fluorite type crystal. According to the above description, these elpasolite adopt the form (M 1/3 □ 2/3 ) 4 X 2 , where M labels the central metal, X stand for the chlorine ions and □ represent the vacancies, which may accommodate a significant amount of defects without collapsing. This experimental study provides the necessary input to test theoretical models against experimental data. (Author)

  17. Zinc(II) complexes with potent cyclin-dependent kinase inhibitors derived from 6-benzylaminopurine: synthesis, characterization, X-ray structures and biological activity

    Czech Academy of Sciences Publication Activity Database

    Trávníček, Zdeněk; Kryštof, Vladimír; Šipl, M.

    2006-01-01

    Roč. 100, č. 2 (2006), s. 214-225 ISSN 0162-0134 R&D Projects: GA ČR GA203/04/1168 Institutional research plan: CEZ:AV0Z50380511 Keywords : Zinc(II) complexes * 6-Benzylaminopurine derivatives * Bohemine * Olomoucine * X-ray structures Subject RIV: CA - Inorganic Chemistry Impact factor: 2.654, year: 2006

  18. Synthesis and single crystal X-ray analysis of two griseofulvin metabolites

    DEFF Research Database (Denmark)

    Rønnest, Mads Holger; Harris, Pernille; Gotfredsen, Charlotte Held

    2010-01-01

    The two phenols, 6-O-desmethyl griseofulvin and 4-O-desmethyl griseofulvin are metabolites of the antifungal drug griseofulvin. Herein, we present an improved synthesis of the 6-phenol derivative, and an unequivocal proof of both structures by single-crystal X-ray analysis.......The two phenols, 6-O-desmethyl griseofulvin and 4-O-desmethyl griseofulvin are metabolites of the antifungal drug griseofulvin. Herein, we present an improved synthesis of the 6-phenol derivative, and an unequivocal proof of both structures by single-crystal X-ray analysis....

  19. Synthesis, characterization and x-ray crystal structure of a dimethyltin (IV) dichloride complex of 2-acetylpyridine benzophenone azine

    International Nuclear Information System (INIS)

    Mustaffa Shamsuddin; Md Abu Affan; Ramli Atan

    1998-01-01

    Dimethyltin dichloride react with 2-ac ethylpyridine benzophenone azine (apba) in refluxing dry hexane to give (SnMe 2 Cl 2 (apba)) where the azine ligand acts as a bidentate N-N chelating ligand. The complex has been characterized by IR spectroscopy, 1 H and 13 C NMR spectroscopic data and elemental analyses. The crystal structure of the dimethyltin(IV) derivative has also been determined. Crystals are monoclinic with space group P2(1)/n with cell dimensions: a = 10.1819(3) Armstrong, b = 18.3113(5) Armstrong, c = 12.6451(4) Armstrong

  20. Chemical synthesis and X-ray structure of a heterochiral {D-protein antagonist plus vascular endothelial growth factor} protein complex by racemic crystallography.

    Science.gov (United States)

    Mandal, Kalyaneswar; Uppalapati, Maruti; Ault-Riché, Dana; Kenney, John; Lowitz, Joshua; Sidhu, Sachdev S; Kent, Stephen B H

    2012-09-11

    Total chemical synthesis was used to prepare the mirror image (D-protein) form of the angiogenic protein vascular endothelial growth factor (VEGF-A). Phage display against D-VEGF-A was used to screen designed libraries based on a unique small protein scaffold in order to identify a high affinity ligand. Chemically synthesized D- and L- forms of the protein ligand showed reciprocal chiral specificity in surface plasmon resonance binding experiments: The L-protein ligand bound only to D-VEGF-A, whereas the D-protein ligand bound only to L-VEGF-A. The D-protein ligand, but not the L-protein ligand, inhibited the binding of natural VEGF(165) to the VEGFR1 receptor. Racemic protein crystallography was used to determine the high resolution X-ray structure of the heterochiral complex consisting of {D-protein antagonist + L-protein form of VEGF-A}. Crystallization of a racemic mixture of these synthetic proteins in appropriate stoichiometry gave a racemic protein complex of more than 73 kDa containing six synthetic protein molecules. The structure of the complex was determined to a resolution of 1.6 Å. Detailed analysis of the interaction between the D-protein antagonist and the VEGF-A protein molecule showed that the binding interface comprised a contact surface area of approximately 800 Å(2) in accord with our design objectives, and that the D-protein antagonist binds to the same region of VEGF-A that interacts with VEGFR1-domain 2.

  1. X-ray structure analysis of soil compositions

    International Nuclear Information System (INIS)

    Tillaev, T.; Kalonov, M.; Kuziev, Sh.; Khatamov, Sh.; Suvanov, M.

    1998-01-01

    The analytic characteristics of techniques developed to analyse soil structure by means of X-ray diffraction method are presented. Presence of 8 minerals in Fergana valley soils have been established. It is shown that X-ray structure analysis of soils gives rise to new original possibilities to determine not only their structure but also quantative content and type of chemical compound of element in soil. (author)

  2. Structure of polysaccharide and structural analysis by x-ray

    International Nuclear Information System (INIS)

    Yuguchi, Yoshiaki

    2010-01-01

    Polysaccharides occur in plants and the living body in the solid, gel, or liquid. They have a highly structural diversity and possess the potential to be used for development of new materials and energy sources. So it is very important to understand their molecular structure under various conditions. This review introduces the structural characteristics of polysaccharides and the examples of their analysis by the X-ray scattering method. (author)

  3. Synthesis of novel O-acylated-D-ribono-1,5-lactones and structural assignment supported by conventional NOESY-NMR and X-ray analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sa, Marcus M.; Silveira, Gustavo P.; Caro, Miguel S.B. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Quimica]. E-mail: msa@qmc.ufsc.br; Ellena, Javier [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Fisica

    2008-07-01

    A practical method for the structural assignment of 3,4-O-benzylidene-D-ribono-1,5-lactones and analogues using conventional NMR techniques and NOESY measurements in solution is described. 2-O-Acyl-3,4-O-benzylidene-D-ribono-1,5-lactones were prepared in good yields by acylation of Zinner's lactone with acyl chlorides under mildly basic conditions. Structural determination of 2-O-(4-nitrobenzoyl)-3,4-O-benzylidene-D-ribono-1,5-lactone was achieved by single crystal x-ray diffraction, which supports the results based on spectroscopic data. (author)

  4. Lanthanide complexes of macrocyclic polyoxovanadates by VO4 units: synthesis, characterization, and structure elucidation by X-ray crystallography and EXAFS spectroscopy.

    Science.gov (United States)

    Nishio, Masaki; Inami, Shinnosuke; Katayama, Misaki; Ozutsumi, Kazuhiko; Hayashi, Yoshihito

    2012-01-16

    Reactions of a tetravanadate anion, [V(4)O(12)](4-), with a series of lanthanide(III) salts yield three types of lanthanide complexes of macrocyclic polyoxovanadates: (Et(4)N)(6)[Ln(III)V(9)O(27)] [Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6)], (Et(4)N)(5)[(H(2)O)Ho(III)(V(4)O(12))(2)] (7), and (Et(4)N)(7)[Ln(III)V(10)O(30)] [Ln = Er (8), Tm (9), Yb (10), Lu (11)]. Lanthanide complexes 1-11 are isolated and characterized by IR, elemental analysis, single-crystal X-ray diffraction, and extended X-ray absorption fine structure spectroscopy (EXAFS). Lanthanide complexes 1-6 are composed of a square-antiprism eight-coordinated Ln(III) center with a macrocyclic polyoxovanadate that is constructed from nine VO(4) tetrahedra through vertex sharing. The structure of 7 is composed of a seven-coordinated Ho(III) center, which exhibits a capped trigonal-prism coordination environment by the sandwiching of two cyclic tetravanadates with a capping H(2)O ligand. Lanthanide complexes 8-11 have a six-coordinated Ln(III) center with a 10-membered vanadate ligand. The structural trend to adopt a larger coordination number for a larger lanthanide ion among the three types of structures is accompanied by a change in the vanadate ring sizes. These lanthanide complexes are examined by EXAFS spectroscopies on lanthanide L(III) absorption edges, and the EXAFS oscillations of each of the samples in the solid state and in acetonitrile are identical. The Ln-O and Ln···V bond lengths obtained from fits of the EXAFS data are consistent with the data from the single-crystal X-ray studies, reflecting retention of the structures in acetonitrile.

  5. Structure in galactic soft X-ray features

    International Nuclear Information System (INIS)

    Davelaar, J.

    1979-01-01

    Observations are described of the soft X-ray background in a part of the northern hemisphere in the energy range 0.06 - 3.0 keV. The X-ray instruments, placed onboard a sounding rocket, are a one-dimensional focusing collector with multi-cell proportional counters in the focal plane and eight large area counters on deployable panels. A description of the instruments and their preflight calibration is given. Precautions were taken to prevent UV sensitivity of the X-ray instruments. The observation program, which consisted of a number of pre-programmed slow scans, is outlined. The spectral date on the soft X-ray background in these and previous observations showed that at least two components of different temperature are present. A low temperature component of approximately (3-10)x10 5 is found all over the sky. Components of higher temperature approximately 3x10 6 K are found in regions of soft X-ray enhancement; The North Polar Spur has been observed in two scans at the galactic latitude b=25 0 and b=75 0 . The X-ray ridge structure is found to be strongly energy dependent. The low energy data ( 0 reveals two separate emission features on the ridge, both probably of finite extensions (approximately equal to 0 0 .5). A wider X-ray ridge (approximately equal to 10 0 ) is observed above 0.4 keV. (Auth.)

  6. A laboratory-based hard x-ray monochromator for high-resolution x-ray emission spectroscopy and x-ray absorption near edge structure measurements

    Energy Technology Data Exchange (ETDEWEB)

    Seidler, G. T., E-mail: seidler@uw.edu; Mortensen, D. R.; Remesnik, A. J.; Pacold, J. I.; Ball, N. A.; Barry, N.; Styczinski, M.; Hoidn, O. R. [Physics Department, University of Washington, Seattle, Washington 98195-1560 (United States)

    2014-11-15

    We report the development of a laboratory-based Rowland-circle monochromator that incorporates a low power x-ray (bremsstrahlung) tube source, a spherically bent crystal analyzer, and an energy-resolving solid-state detector. This relatively inexpensive, introductory level instrument achieves 1-eV energy resolution for photon energies of ∼5 keV to ∼10 keV while also demonstrating a net efficiency previously seen only in laboratory monochromators having much coarser energy resolution. Despite the use of only a compact, air-cooled 10 W x-ray tube, we find count rates for nonresonant x-ray emission spectroscopy comparable to those achieved at monochromatized spectroscopy beamlines at synchrotron light sources. For x-ray absorption near edge structure, the monochromatized flux is small (due to the use of a low-powered x-ray generator) but still useful for routine transmission-mode studies of concentrated samples. These results indicate that upgrading to a standard commercial high-power line-focused x-ray tube or rotating anode x-ray generator would result in monochromatized fluxes of order 10{sup 6}–10{sup 7} photons/s with no loss in energy resolution. This work establishes core technical capabilities for a rejuvenation of laboratory-based hard x-ray spectroscopies that could have special relevance for contemporary research on catalytic or electrical energy storage systems using transition-metal, lanthanide, or noble-metal active species.

  7. New Cu (II), Co(II) and Ni(II) complexes of chalcone derivatives: Synthesis, X-ray crystal structure, electrochemical properties and DFT computational studies

    Science.gov (United States)

    Tabti, Salima; Djedouani, Amel; Aggoun, Djouhra; Warad, Ismail; Rahmouni, Samra; Romdhane, Samir; Fouzi, Hosni

    2018-03-01

    The reaction of nickel(II), copper(II) and cobalt(II) with 4-hydroxy-3-[(2E)-3-(1H-indol-3-yl)prop-2-enoyl]-6-methyl-2H-pyran-2-one (HL) leads to a series of new complexes: Ni(L)2(NH3), Cu(L)2(DMF)2 and Co(L)2(H2O). The crystal structure of the Cu(L)2(DMF)2 complex have been determined by X-ray diffraction methods. The Cu(II) lying on an inversion centre is coordinated to six oxygen atoms forming an octahedral elongated. Additionally, the electrochemical behavior of the metal complexes were investigated by cyclic voltammetry at a glassy carbon electrode (GC) in CH3CN solutions, showing the quasi-reversible redox process ascribed to the reduction of the MII/MI couples. The X-ray single crystal structure data of the complex was matched excellently with the optimized monomer structure of the desired compound; Hirschfeld surface analysis supported the packed crystal lattice 3D network intermolecular forces. HOMO/LUMO energy level and the global reactivity descriptors quantum parameters are also calculated. The electrophilic and nucleophilic potions in the complex surface are theoretically evaluated by molecular electrostatic potential and Mulliken atomic charges analysis.

  8. Design, Synthesis, and X-ray Crystal Structures of 2,4-Diaminofuro[2,3-d]pyrimidines as Multireceptor Tyrosine Kinase and Dihydrofolate Reductase Inhibitors

    Science.gov (United States)

    Gangjee, Aleem; Li, Wei; Lin, Lu; Zeng, Yibin; Ihnat, Michael; Warnke, Linda A.; Green, Dixy W.; Cody, Vivian; Pace, Jim; Queener, Sherry F.

    2009-01-01

    To optimize dual receptor tyrosine kinase (RTK) and dihydrofolate reductase (DHFR) inhibition, the E- and Z-isomers of 5-[2-(2-methoxyphenyl)prop-1-en-1-yl]furo[2,3-d]pyrimidine-2,4-diamines (1a and 1b) were separated by HPLC and the X-ray crystal structures (2.0 Å and 1.4 Å respectively) with mouse DHFR and NADPH as well as 1b with human DHFR (1.5 Å) were determined. The E- and Z-isomers adopt different binding modes when bound to mouse DHFR. A series of 2,4-diaminofuro[2,3-d]pyrimidines 2–13 were designed and synthesized using the X-ray crystal structures of 1a and 1b with DHFR to increase their DHFR inhibitory activity. Wittig reactions of appropriate 2-methoxyphenyl ketones with 2,4-diamino-6-chloromethyl furo[2,3-d]pyrimidine afforded the C8–C9 unsaturated compounds 2–7 and catalytic reduction gave the saturated 8–13. Homologation of the C9-methyl analog maintains DHFR inhibitory activity. In addition, inhibition of EGFR and PDGFR-β were discovered for saturated C9-homologated analogs 9 and 10 that were absent in the saturated C9-methyl analogs. PMID:19748785

  9. X-ray structural analysis of some Indian coals

    International Nuclear Information System (INIS)

    Binoy K Saikia, B.K.

    2009-01-01

    Coal is one of the most abundant energy resources and has the capability to meet future energy needs with high reliability. The use of coal as an energy source and as a source of organic chemicals feedstock may become more important in the future. It is physically and chemically a heterogeneous and carbonaceous rock which consists of organic and inorganic materials. Assam coal has been, and continuous to be, a valuable energy source, especially for the various industry in India and for liquefactions of coal. The basic chemical structure of coal that has been widely accepted today was built up from the synthesis of results obtained from X-ray diffraction data. The present paper reports a comparative investigation of coals from different collieries/areas of Makum coal field, Assam viz. Ledo, Tikak, Baragolai, Tipong and Tirap collieries Makum coal field, Assam with the help of X-ray diffraction (XRD). The X-ray diffraction patterns indicate that the coals are amorphous in nature. The present XRD method includes the evaluation of Function of Radial Distribution of Atoms (FRDA) and structural interpretations of the coals from their Radial Distribution Function (RDF) plots after proper corrections for air scatter, absorption by sample and polarization. The curve intensity profiles in FRDA clearly show quite regular molecular packets for these coals. The first maxima in the FRDA curves was obtained at r= 0.4 Amstrong for Ledo, Baragolai and Tipong coals whereas for Tikak coal it was observed at r= 0.5 Amstrong. The first maximum in the pair distribution function plots, G (r) of Ledo, Tikak, and Tipong coals was obtained at r=0.15 nm whereas for Baragolai and Tirap coals it was observed at r=0.14 nm and r=0.12 nm respectively, which relates to the C=C (aliphatic/aromatic) bonds in coal matrix. The Assam coal samples from Ledo, Tikak, Baragolai, Tipong and Tirap collieries of Makum coalfield have almost the same RDF inter-atomic distances except slight differences. This

  10. 5-Arylidene derivatives of Meldrum's acid: Synthesis, structural characterization using single crystal and powder crystal X-ray diffraction, and electronic properties

    Science.gov (United States)

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

    2015-07-01

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

  11. Nickel complexes of o-amidochalcogenophenolate(2-)/o-iminochalcogenobenzosemiquinonate(1-) pi-radical: synthesis, structures, electron spin resonance, and x-ray absorption spectroscopic evidence.

    Science.gov (United States)

    Hsieh, Chung-Hung; Hsu, I-Jui; Lee, Chien-Ming; Ke, Shyue-Chu; Wang, Tze-Yuan; Lee, Gene-Hsiang; Wang, Yu; Chen, Jin-Ming; Lee, Jyh-Fu; Liaw, Wen-Feng

    2003-06-16

    The preparation of complexes trans-[Ni(-SeC(6)H(4)-o-NH-)(2)](-) (1), cis-[Ni(-TeC(6)H(4)-o-NH-)(2)](-) (2), trans-[Ni(-SC(6)H(4)-o-NH-)(2)](-) (3), and [Ni(-SC(6)H(4)-o-S-)(2)](-) (4) by oxidative addition of 2-aminophenyl dichalcogenides to anionic [Ni(CO)(SePh)(3)](-) proves to be a successful approach in this direction. The cis arrangement of the two tellurium atoms in complex 2 is attributed to the intramolecular Te.Te contact interaction (Te.Te contact distance of 3.455 A). The UV-vis electronic spectra of complexes 1 and 2 exhibit an intense absorption at 936 and 942 nm, respectively, with extinction coefficient epsilon > 10000 L mol(-)(1) cm(-)(1). The observed small g anisotropy, the principal g values at g(1) = 2.036, g(2) = 2.062, and g(3) = 2.120 for 1 and g(1) = 2.021, g(2) = 2.119, and g(3) = 2.250 for 2, respectively, indicates the ligand radical character accompanied by the contribution of the singly occupied d orbital of Ni(III). The X-ray absorption spectra of all four complexes show L(III) peaks at approximately 854.5 and approximately 853.5 eV. This may indicate a variation of contribution of the Ni(II)-Ni(III) valence state. According to the DFT calculation, the unpaired electron of complex 1 and 2 is mainly distributed on the 3d(xz)() orbital of the nickel ion and on the 4p(z)() orbital of selenium (tellurium, 5p(z)()) as well as the 2p(z)() orbital of nitrogen of the ligand. On the basis of X-ray structural data, UV-vis absorption, electron spin resonance, magnetic properties, DFT computation, and X-ray absorption (K- and L-edge) spectroscopy, the monoanionic trans-[Ni(-SeC(6)H(4)-o-NH-)(2)](-) and cis-[Ni(-TeC(6)H(4)-o-NH-)(2)](-) complexes are appositely described as a resonance hybrid form of Ni(III)-bis(o-amidochalcogenophenolato(2-)) and Ni(II)-(o-amidochalcogenophenolato(2-))-(o-iminochalcogenobenzosemiquinonato(1-) pi-radical; i.e., complexes 1 and 2 contain delocalized oxidation levels of the nickel ion and ligands.

  12. X-ray structure based evaluation of analogs of citalopram

    DEFF Research Database (Denmark)

    Topiol, Sid; Bang-Andersen, Benny; Sanchez, Connie

    2017-01-01

    The recent publication of X-ray structures of SERT includes structures with the potent antidepressant S-Citalopram (S-Cit). Earlier predictions of ligand binding at both a primary (S1) and an allosteric modulator site (S2), were confirmed. We provide herein examples of a series of Citalopram anal...

  13. Synthesis, spectroscopy and antimicrobial activity of vanadium(III) and vanadium(IV) complexes involving Schiff bases derived from tranexamic acid and X-ray structure of Zwitter ion of tranexamic acid

    International Nuclear Information System (INIS)

    Shahzadi, S.; Ali, S.; Badshah, A.; Parvez, M.; Ahmed, E.; Malik, A.

    2007-01-01

    The synthesis of six new vanadium complexes of Schiff base derived from Tranexamic acid is reported. All the complexes were characterized by elemental analysis, infrared, electronic spectra, and mass spectrometry. FTIR data reveals that the Schiff base acts as a bidentate and the complexes exhibit the hexa-coordinated geometry in solid state. These complexes were screened for their biological activity against various bacterial and fungal strains. All the ligands show higher activity after complexation. The crystal structure of the Zwitter ion of the Tranexamic acid has been determined by X-ray single crystal diffraction [ru

  14. Functional coordination polymers and MOFs from reactions of the lanthanides and barium with azole ligands. Synthesis and characterization with a focus on structure determination from X-ray powder diffraction data

    International Nuclear Information System (INIS)

    Rybak, Jens-Christoph

    2012-01-01

    This thesis deals with the synthesis and characterization of coordination polymers and MOFs of the lanthanides and barium with different azolic N-heterocycles. A total of 18 new organic-inorganic hybrid materials, as well as a series of co-doped compounds is presented. Besides the structural characterization of these materials from X-ray diffraction powder data, the focus of the investigations is on the thermal and photoluminescence spectroscopic properties. The lanthanides La - Lu, except Eu and Pm, can be reacted with 1H-1,2,3-triazole to give the series of the isotypic dense 3D-MOFs 3 ∞ [Ln(Tz * ) 3 ]. Investigation of the photoluminescence properties of these compounds reveals a broad range of different luminescence phenomena, including the first observation of an intrinsic inner-filter effect of the Ln 3+ -ions. The structure of this isotypic series of compounds was solved and refined from X-ray powder diffraction data. A 2D-polymorph of these compounds 2 ∞ [Ln(Tz * ) 3 ], is observed for Ln = Sm, Tb and was characterized by single crystal data. The reaction of Eu with 1H-benzotriazole yields the 1D-coordination polymer 1 ∞ [Eu(Btz) 2 (BtzH) 2 ], which is the first example of a divalent rare earth benzotriazolate. Analysis of the thermal properties reveals the transformation to the 3D-MOF 3 ∞ [Eu(Btz) 2 ] at higher temperatures. The structure of this material was also solved from X-ray powder diffraction data. Investigation of the photoluminescence properties of the co-doped compounds 3 ∞ [Ba 1-x Eu x (Im) 2 ], which were obtained from reaction of the salt-like hydrides BaH 2 and EuH 2 with imidazole, show that the synthesis of luminescent MOF materials by co-doping of non-luminescent networks with luminescence centers is possible. The structure of these materials was solved from X-ray powder diffraction data of the undoped compound 3 ∞ [BaEu(Im) 2 ]. Structural characterization of materials from X-ray powder diffraction data is an important aspect

  15. Astrophysical extended X-ray absorption fine-structure analysis

    International Nuclear Information System (INIS)

    Woo, J.W.; Forrey, R.C.; Cho, K.; Department of Physics and Division of Applied Sciences, Harvard University)

    1997-01-01

    We present an astrophysical extended X-ray absorption fine-structure (EXAFS) analysis (AEA) tool. The AEA tool is designed to generate a numerical model of the modification to the X-ray absorption coefficient due to the EXAFS phenomenon. We have constructed a complete database (elements up to the atomic number 92) of EXAFS parameters: central atom phase shift (2δ 1 ), backscattering phase shift (φ b ), and backscattering amplitude (F). Using the EXAFS parameter data base, the AEA tool can generate a numerical model of any compound when the atomic numbers of neighboring atoms and their distances to the central X-ray-absorbing atom are given. copyright 1997 The American Astronomical Society

  16. Synthesis, characterization, electrochemical studies and X-ray structures of mixed-ligand polypyridyl copper(II complexes with the acetate

    Directory of Open Access Journals (Sweden)

    Adekunle Oluwafunmilayo F.

    2016-01-01

    Full Text Available [Cu(phen2(CH3COO](ClO4.2H2O (1 and [Cu(bipy2(CH3COO]-(ClO4.H2O (2 {phen = 1,10-phenanthroline, bipy = 2,2’-bipyridine}were synthesized and characterized. The complexes were characterized by employying elemental analyses, infrared and UV-Visible spectroscopy, room temperature magnetic measurements and the crystal structures elucidated using X-ray diffraction experiment. The redox properties of the complexes were also investigated. Both structures have a square pyramidal CuN4O chromophore which exhibit significant distortions due to long Cu-O [2.217(3 Å for (1 and 2.179 (1 for (2] and Cu-N [2.631(2 Å for (1 and 2.714(1 Å for (2] bonds. This distortion if further shown by the O-Cu-N bond angles [147.71(8 o for (1 and 153.40(5 o for (2]. The elemental analyses further support the structural details unveiled by the single crystal X-ray diffraction analysis. The infrared spectra shows the acetate vibrational frequencies at 1587 cm-1,1428 cm-1, 1314 cm-1 for (1 and 1571 cm-1, 1441 cm-1, 1319c m-1 for (2 and the perchlo-rate bands at 1059 cm-1, 720 cm-1 (1 and 1080 cm-1,768 cm-1 (2. The broad d-d bands for the copper ion at 14,514 cm-1(1 and 14,535 cm-1(2 support the adoption of square pyramid geometries. The magnetic moments for the two complexes are 1.83 B.M for (1 and 1.72 B.M for (2. The peak to peak values of the two complexes show that the electrode reactions are quasi-reversibile with ΔEp = 0.023V (1 and 0.025V for (2. In both structures, there are π-π intermolecular interactions in addition to hydrogen bonding between the units.

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

    International Nuclear Information System (INIS)

    Gulden, Johannes

    2013-03-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Gulden, Johannes

    2013-03-15

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

  19. Theoretical approaches to x-ray absorption fine structure

    International Nuclear Information System (INIS)

    Rehr, J. J.; Albers, R. C.

    2000-01-01

    Dramatic advances in the understanding of x-ray absorption fine structure (XAFS) have been made over the past few decades, which have led ultimately to a highly quantitative theory. This review covers these developments from a unified multiple-scattering viewpoint. The authors focus on extended x-ray absorption fine structure (EXAFS) well above an x-ray edge, and, to a lesser extent, on x-ray absorption near-edge structure (XANES) closer to an edge. The discussion includes both formal considerations, derived from a many-electron formulation, and practical computational methods based on independent-electron models, with many-body effects lumped into various inelastic losses and energy shifts. The main conceptual issues in XAFS theory are identified and their relative importance is assessed; these include the convergence of the multiple-scattering expansion, curved-wave effects, the scattering potential, inelastic losses, self-energy shifts, and vibrations and structural disorder. The advantages and limitations of current computational approaches are addressed, with particular regard to quantitative experimental comparisons. (c) 2000 The American Physical Society

  20. Structured scintillators for X-ray imaging with micrometre resolution

    DEFF Research Database (Denmark)

    Olsen, Ulrik Lund; Schmidt, Søren; Poulsen, Henning Friis

    2009-01-01

    A 3D X-ray detector for imaging of 30–200 keV photons is described. It comprises a stack of semitransparent structured scintillators, where each scintillator is a regular array of waveguides in silicon, and with pores filled with CsI. The performance of the detector is described theoretically...

  1. Structural Investigations of Nanowires Using X-Ray Diffraction

    DEFF Research Database (Denmark)

    Stankevic, Tomas

    Advancements in growth of the nanowire-based devices opened another dimension of possible structures and material combinations, which nd their applications in a wide variety of elds, including everyday life. Characterization of such devices brings its own challenges and here we show that X-rays oer...

  2. Structure-Based Design: Synthesis, X-ray Crystallography, and Biological Evaluation of N-Substituted-4-Hydroxy-2-Quinolone-3-Carboxamides as Potential Cytotoxic Agents.

    Science.gov (United States)

    Sabbah, Dima A; Hishmah, Bayan; Sweidan, Kamal; Bardaweel, Sanaa; AlDamen, Murad; Zhong, Haizhen A; Abu Khalaf, Reema; Hasan Ibrahim, Ameerah; Al-Qirim, Tariq; Abu Sheikha, Ghassan; Mubarak, Mohammad S

    2018-01-01

    Oncogenic potential of phosphatidylinositol 3-kinase (PI3Kα) has been highlighted as a therapeutic target for anticancer drug design. Target compounds were designed to address the effect of different substitution patterns at the N atom of the carboxamide moiety on the bioactivity of this series. Synthesis of the targeted compounds, crystallography, biological evaluation tests against human colon carcinoma (HCT-116), and Glide docking studies. A new series of N-substituted- 4-hydroxy-2-quinolone-3-carboxamides was prepared and characterized by means of FT-IR, 1H and 13C NMR, and elemental analysis. In addition, the identity of the core nucleus 5 was successfully characterized with the aid of X-ray crystallography. Biological activity of prepared compounds was investigated in vitro against human colon carcinoma (HCT-116) cell line. Results revealed that these compounds inhibit cell proliferation and induce apoptosis through an increase in caspase-3 activity and a decrease in DNA cellular content. Compounds 7, 14, and 17 which have H-bond acceptor moiety on p-position displayed promising PI3Kα inhibitory activity. On the other hand, derivatives tailored with bulky and hydrophobic motifs (16 and 18) on o- and m-positions exhibited moderate activity. Molecular docking studies against PI3Kα and caspase-3 showed an agreement between the predicted binding affinity (ΔGobsd) and IC50 values of the derivatives for the caspase-3 model. Furthermore, Glide docking studies against PI3Kα demonstrated that the newly synthesized compounds accommodate PI3Kα kinase catalytic domain and form H-bonding with key binding residues. The series exhibited a potential PI3Kα inhibitory activity in HCT-116 cell line. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  3. Synthesis and X-ray Crystal Structure of a Stable cis-1,2-bis(diphenylphosphinoethene Monodentate Thiolate Platinum Complex and TGA Studies of its Precursors

    Directory of Open Access Journals (Sweden)

    Vaz Rodrigo H.

    2002-01-01

    Full Text Available The stable Pt(II complex [Pt(SPh2(dppen (4, (dppen, Ph2PCH=CHPPh2 was obtained from [PtCl(SPh2(SnPh3cod] (1 (cod = 1,5-cyclooctadiene by reductive elimination reaction of SnClPh3 and substitution of the cod ligand by the diphosphine, albeit in low yields. Yields of 80% were obtained when [Pt(SPh2cod] (3 was used as the starting material instead. The viability of these reactions was suggested by a TG study, performed on the starting materials. Complex 4 was characterized by multinuclear NMR (195Pt, 31P, ¹H and 13C and IR spectroscopies and elemental analysis. The molecular structure, solved by an X-ray diffraction study, exhibted a slightly distorted square-planar geometry and short C=C and Pt-P bond distances which were interpreted in terms of a p interaction between the double bond and the metal-ligand bond, as observed for other diphosphine compounds described previously.

  4. X-ray lasers for structural and dynamic biology

    International Nuclear Information System (INIS)

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

    2012-01-01

    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. (key issues reviews)

  5. The development of structural x-ray crystallography

    Science.gov (United States)

    Woolfson, M. M.

    2018-03-01

    From its birth in 1912, when only the simplest structures could be solved, x-ray structural crystallography is now able to solve macromolecular structures containing many thousands of independent non-hydrogen atoms. This progress has depended on, and been driven by, great technical advances in the development of powerful synchrotron x-ray sources, advanced automated equipment for the collection and storage of large data sets and powerful computers to deal with everything from data processing to running programmes employing complex algorithms for the automatic solution of structures. The sheer number of developments in the subject over the past century makes it impossible for this review to be exhaustive, but it will describe some major developments that will enable the reader to understand how the subject has grown from its humble beginnings to what it is today.

  6. Synthesis of 2-deoxy-2,2-difluoro-α-maltosyl fluoride and its X-ray structure in complex with Streptomyces coelicolor GlgEI-V279S

    Energy Technology Data Exchange (ETDEWEB)

    Thanna, Sandeep; Lindenberger, Jared J.; Gaitonde, Vishwanath V.; Ronning, Donald R.; Sucheck, Steven J. (Toledo)

    2015-06-05

    Streptomyces coelicolor (Sco) GlgEI is a glycoside hydrolase involved in α-glucan biosynthesis and can be used as a model enzyme for structure-based inhibitor design targeting Mycobacterium tuberculosis (Mtb) GlgE. The latter is a genetically validated drug target for the development of anti-Tuberculosis (TB) treatments. Inhibition of Mtb GlgE results in a lethal buildup of the GlgE substrate maltose-1-phosphate (M1P). However, Mtb GlgE is difficult to crystallize and affords lower resolution X-ray structures. Sco GlgEI-V279S on the other hand crystallizes readily, produces high resolution X-ray data, and has active site topology identical to Mtb GlgE. We report the X-ray structure of Sco GlgEI-V279S in complex with 2-deoxy-2,2-difluoro-α-maltosyl fluoride (α-MTF, 5) at 2.3 Å resolution. α-MTF was designed as a non-hydrolysable mimic of M1P to probe the active site of GlgE1 prior to covalent bond formation without disruption of catalytic residues. The α-MTF complex revealed hydrogen bonding between Glu423 and the C1F which provides evidence that Glu423 functions as proton donor during catalysis. Further, hydrogen bonding between Arg392 and the axial C2 difluoromethylene moiety of α-MTF was observed suggesting that the C2 position tolerates substitution with hydrogen bond acceptors. The key step in the synthesis of α-MDF was transformation of peracetylated 2-fluoro-maltal 1 into peracetylated 2,2-difluoro-α-maltosyl fluoride 2 in a single step via the use of Selectfluor®

  7. Diastereoselective synthesis of ethyl ( Z)-3-(8-methylimidazo-[1,2- a]pyrid-2-yl)-2-phenylthioacrylate. X-ray crystal structure and conformational analysis

    Science.gov (United States)

    Gautier, A.; Roche, D.; Métin, J.; Carpy, A.; Madesclaire, M.

    1995-09-01

    The title compound 2, a gem vinyl sulfide ester, has been obtained diastereoselectively (de > 98%) by action of the ethyl thiophenoxyacetate carbanion on the imidazo[1,2- a]pyridinecarbaldehyde 1 in a basic medium, at low temperature. The X-ray crystal structure of 2 (C 19H 19N 2O 2S: Mr = 338.43, triclinic, P 1¯, a = 8.193(3) Å, b = 10.090(2) Å, c = 10.981(4) Å, α = 88.12(2)°, β = 78.66(4)°, γ = 78.53(2)°, V = 872.3(6) Å3, Z = 2, Dcalc = 1.29 g cm -3, λ( Mo Kα) = 0.71069 Å, μ = 0.189 mm -1, F(000) = 356, T = 293 K, R = 0.043 for 3610 observed reflections) has been determined and confirmed the Z configuration. The molecule is almost planar except for the phenyl ring situated in an approximate perpendicular plane. Despite the presence of the conjugate double bonds of the vinyl ester group (acrylate), coplanar with the imidazopyridine heterocycle, there is no evidence of π-electron delocalization over the whole structure. The crystal cohesion is ensured by a dense network of van der Waals contacts. A conformational analysis of the Z and E isomers by means of a Monte Carlo search and a stochastic dynamics simulation in CHCl 3 has shown that according to the method the Z isomer is more stable than the E isomer by about 7 to 10 kJ mol -1.

  8. Diffraction anomalous fine structure using X-ray anomalous dispersion

    International Nuclear Information System (INIS)

    Soejima, Yuji; Kuwajima, Shuichiro

    1998-01-01

    A use of X-ray anomalous dispersion effects for structure investigation has recently been developed by using synchrotron radiation. One of the interesting method is the observation of anomalous fine structure which arise on diffraction intensity in energy region of incident X-ray at and higher than absorption edge. The phenomenon is so called Diffraction Anomalous Fine Structure (DAFS). DAFS originates in the same physical process an that of EXAFS: namely photoelectric effect at the corresponding atom and the interaction of photoelectron waves between the atom and neighboring atoms. In contrast with EXAFS, the method is available for only the crystalline materials, but shows effective advantages of the structure investigations by a use of diffraction: one is the site selectivity and the other is space selectivity. In the present study, demonstrations of a use of X-ray anomalous dispersion effect for the superstructure determination will be given for the case of PbZrO 3 , then recent trial investigations of DAFS in particular on the superlattice reflections will be introduced. In addition, we discuss about Forbidden Reflection near Edge Diffraction (FRED) which is more recently investigated as a new method of the structure analysis. (author)

  9. Parallelization for X-ray crystal structural analysis program

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Hiroshi [Japan Atomic Energy Research Inst., Tokyo (Japan); Minami, Masayuki; Yamamoto, Akiji

    1997-10-01

    In this report we study vectorization and parallelization for X-ray crystal structural analysis program. The target machine is NEC SX-4 which is a distributed/shared memory type vector parallel supercomputer. X-ray crystal structural analysis is surveyed, and a new multi-dimensional discrete Fourier transform method is proposed. The new method is designed to have a very long vector length, so that it enables to obtain the 12.0 times higher performance result that the original code. Besides the above-mentioned vectorization, the parallelization by micro-task functions on SX-4 reaches 13.7 times acceleration in the part of multi-dimensional discrete Fourier transform with 14 CPUs, and 3.0 times acceleration in the whole program. Totally 35.9 times acceleration to the original 1CPU scalar version is achieved with vectorization and parallelization on SX-4. (author)

  10. In situ X-ray powder diffraction, synthesis, and magnetic properties of InVO 3

    Science.gov (United States)

    Lundgren, Rylan J.; Cranswick, Lachlan M. D.; Bieringer, Mario

    2006-12-01

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

  11. Dynamical X-ray scattering from the relaxed structures

    International Nuclear Information System (INIS)

    Benediktovitch, A.; Feranchuk, I.; Ulyanenkov, A.

    2009-01-01

    High-resolution X-ray diffraction is now widely used analytical tool for investigation of nano scale multilayered structures in semiconductor and optical technologies. The HRXRD method delivers unique information on the crystallographic lattice of the samples, concentration of solid solutions, lattice mismatches, layer thicknesses, defect distribution, and relaxation degree of the epitaxial layers. The evaluation of the experimental results, however, requires a robust and precise theory due to complex dynamical scattering of X-rays from near perfect crystallographic structure of the samples. Usually, the Takagi-Taupin approach [1] or the recurrent matrix methods [2] are used for the simulation of the X-ray diffraction profiles from the epitaxial multilayered structures. The use of these theories, however, becomes essentially difficult, when the lateral lattice mismatches are present in multilayers, for example, in the case of partially or fully relaxed epitaxially grown samples. In the present work, the general solution of this problem is found analytically. The angular divergence of the incident beam is also considered and the algorithm for the diffracted profile mapping in the reciprocal space is developed. The experimental reciprocal space mapping of typical AlGaN/GaN/AlN samples with partially relaxed layers is compared to the simulated maps, which describe well the location and character of the diffraction spots caused by different layers. (author)

  12. Quantitative X-ray determination of CFRP micro structures

    International Nuclear Information System (INIS)

    Hentschel, Manfred P.; Mueller, Bernd R.; Lange, Axel; Wald, Oliver

    2008-01-01

    Beyond imaging the mass distribution of materials by X-ray absorption techniques recent synchrotron and laboratory X-ray refraction techniques provide interface contrast imaging of micro structures. This is of specific relevance to carbon fibre composites (CFRP) which constitute advanced aerospace components. Apart from merely finding isolated flaws like cracks or pores within the natural high interface density only the quantitative measurement of the differences after defined mechanical treatment provides a reliable understanding of the related macroscopic properties. The contribution of the fibre matrix interface of CFRP laminates to the mechanical properties is investigated by relating the mechanical damage to the additional fibre debonding after impact and fatigue. Composites of industrially sized carbon fibres for aerospace applications and of unsized fibres are compared. (orig.)

  13. Colliding Stellar Winds Structure and X-ray Emission

    Science.gov (United States)

    Pittard, J. M.; Dawson, B.

    2018-04-01

    We investigate the structure and X-ray emission from the colliding stellar winds in massive star binaries. We find that the opening angle of the contact discontinuity (CD) is overestimated by several formulae in the literature at very small values of the wind momentum ratio, η. We find also that the shocks in the primary (dominant) and secondary winds flare by ≈20° compared to the CD, and that the entire secondary wind is shocked when η ≲ 0.02. Analytical expressions for the opening angles of the shocks, and the fraction of each wind that is shocked, are provided. We find that the X-ray luminosity Lx∝η, and that the spectrum softens slightly as η decreases.

  14. Extended X-ray absorption fine structure and X-ray diffraction studies on supported Ni catalysts

    International Nuclear Information System (INIS)

    Aldea, N.; Marginean, P.; Yaning, Xie; Tiandou, Hu; Tao, Liu; Wu, Zhongua; ZhenYa, Dai

    1999-01-01

    In the first part of this paper, we present a study based on EXAFS spectroscopy. This method can yield structural information about the local environment around a specific atomic constituent in the amorphous materials, the location and chemical state of any catalytic atom on any support or point defect structures, in alloys and composites. EXAFS is a specific technique of the scattering of X-ray on materials. The present study is aimed toward elucidation of the local structure of Ni atoms and their interaction with oxide support. The second goal of the paper consists in X-ray diffraction on the same samples. X-ray diffraction method that is capable to determine average particle size, microstrains, probability of faults as well as particle size distribution function of supported Ni catalysts is presented. The method is based on the Fourier analysis of a single X-Ray diffraction profile. The results obtained on supported nickel catalysts, which are used in H/D isotopic exchange reactions are reported. The global structure is obtained with a new fitting method based on the Generalised Fermi Function facilities for approximation and Fourier transform of the experimental X-Ray line profiles. Both types of measurements were performed on Beijing Synchrotron Radiation Facilities (BSRF). (authors)

  15. Synthesis of the hexaamine ligand 1,4,7-tris(3-aminopropyl)-1,4,7-triazacyclononane: Reactivity and x-ray crystal structures of the nickel(II) and cobalt(III) complexes

    International Nuclear Information System (INIS)

    Bushnell, G.W.; Fortier, D.G.; McAuley, A.

    1988-01-01

    The synthesis of the ligand 1,4,7-tris(3-aminopropyl)-1,4,7-triazacyclononane(tapacn) can be achieved by the reaction of 1,4,7-triazacyclononane with an excess of acetonitrile, followed by reduction of the nitrile with sodium metal in toluene. Halide salts of the cobalt(III)(complex A) and nickel(II)(complex B) ions have been prepared and examined by using x-ray crystallography. The crystal structures are reported. The 13 C NMR spectrum of the dismagnetic d 6 Co(III) complex ion is reported. A discussion of the two ligand structures deals with the ligand opening and with trigonal twist angle as related to metal ion size and mechanism for redox processes of the complex. 45 refs., 6 figs., 9 tabs

  16. Structural enzymology using X-ray free electron lasers

    Directory of Open Access Journals (Sweden)

    Christopher Kupitz

    2017-07-01

    Full Text Available Mix-and-inject serial crystallography (MISC is a technique designed to image enzyme catalyzed reactions in which small protein crystals are mixed with a substrate just prior to being probed by an X-ray pulse. This approach offers several advantages over flow cell studies. It provides (i room temperature structures at near atomic resolution, (ii time resolution ranging from microseconds to seconds, and (iii convenient reaction initiation. It outruns radiation damage by using femtosecond X-ray pulses allowing damage and chemistry to be separated. Here, we demonstrate that MISC is feasible at an X-ray free electron laser by studying the reaction of M. tuberculosis ß-lactamase microcrystals with ceftriaxone antibiotic solution. Electron density maps of the apo-ß-lactamase and of the ceftriaxone bound form were obtained at 2.8 Å and 2.4 Å resolution, respectively. These results pave the way to study cyclic and non-cyclic reactions and represent a new field of time-resolved structural dynamics for numerous substrate-triggered biological reactions.

  17. X-ray diffraction and X-ray standing-wave study of the lead stearate film structure

    Energy Technology Data Exchange (ETDEWEB)

    Blagov, A. E.; Dyakova, Yu. A.; Kovalchuk, M. V.; Kohn, V. G.; Marchenkova, M. A.; Pisarevskiy, Yu. V.; Prosekov, P. A., E-mail: prosekov@crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2016-05-15

    A new approach to the study of the structural quality of crystals is proposed. It is based on the use of X-ray standing-wave method without measuring secondary processes and considers the multiwave interaction of diffraction reflections corresponding to different harmonics of the same crystallographic reflection. A theory of multiwave X-ray diffraction is developed to calculate the rocking curves in the X-ray diffraction scheme under consideration for a long-period quasi-one-dimensional crystal. This phase-sensitive method is used to study the structure of a multilayer lead stearate film on a silicon substrate. Some specific structural features are revealed for the surface layer of the thin film, which are most likely due to the tilt of the upper layer molecules with respect to the external normal to the film surface.

  18. Synthesis, X-ray crystal structures, and phosphate ester cleavage properties of bis(2-pyridylmethyl)amine copper(II) complexes with guanidinium pendant groups.

    Science.gov (United States)

    Belousoff, Matthew J; Tjioe, Linda; Graham, Bim; Spiccia, Leone

    2008-10-06

    Three new derivatives of bis(2-pyridylmethyl)amine (DPA) featuring ethylguanidinium (L (1)), propylguanidinium (L (2)), or butylguanidinium (L (3)) pendant groups have been prepared by the reaction of N, N- bis(2-pyridylmethyl)alkane-alpha,omega-diamines with 1 H-pyrazole-1-carboxamidine hydrochloride. The corresponding mononuclear copper(II) complexes were prepared by reacting the ligands with copper(II) nitrate and were isolated as [Cu(LH (+))(OH 2)](ClO 4) 3. xNaClO 4. yH 2O ( C1: L = L (1), x = 2, y = 3; C2: L = L (2), x = 2, y = 4; C3: L = L (3), x = 1, y = 0) following cation exchange purification. Recrystallization yielded crystals of composition [Cu(LH (+))(X)](ClO 4) 3.X ( C1': L = L (1), X = MeOH; C2': L = L (2), X = H 2O; C3': L = L (3), X = H 2O), which were suitable for X-ray crystallography. The crystal structures of C1', C2', and C3' indicate that the DPA moieties of the ligands coordinate to the copper(II) centers in a meridional fashion, with a water or methanol molecule occupying the fourth basal position. Weakly bound perchlorate anions located in the axial positions complete the distorted octahedral coordination spheres. The noncoordinating, monoprotonated guanidinium groups project away from the Cu(II)-DPA units and are involved in extensive charge-assisted hydrogen-bonding interactions with cocrystallized water/methanol molecules and perchlorate anions within the crystal lattices. The copper(II) complexes were tested for their ability to promote the cleavage of two model phosphodiesters, bis( p-nitrophenyl)phosphate (BNPP) and uridine-3'- p-nitrophenylphosphate (UpNP), as well as supercoiled plasmid DNA (pBR 322). While the presence of the guanidine pendants was found to be detrimental to BNPP cleavage efficiency, the functionalized complexes were found to cleave plasmid DNA and, in some cases, the model ribose phosphate diester, UpNP, at a faster rate than the parent copper(II) complex of DPA.

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

    DEFF Research Database (Denmark)

    Yennawar, Hemant; Møller, Magda; Gillilan, Richard

    2011-01-01

    The X-ray crystal structure of sheep liver sorbitol dehydrogenase (slSDH) has been determined using the crystal structure of human sorbitol dehydrogenase (hSDH) as a molecular-replacement model. slSDH crystallized in space group I222 with one monomer in the asymmetric unit. A conserved tetramer...

  20. Testing ion structure models with x-ray Thomson scattering

    Directory of Open Access Journals (Sweden)

    Wünsch K.

    2013-11-01

    Full Text Available We investigate the influence of various ionic structure models on the interpretation of the X-ray Thomson scattering signal. For the calculation of the ion structure, classical hypernetted chain equations are used applying different effective inter-particle potentials. It is shown that the different models lead to significant discrepancies in the theoretically predicted weight of the Rayleigh peak, in particular for small k-values where correlation effects are important. Here, we propose conditions which might allow for an experimental verification of the theories under consideration of experimental constraints of k-vector blurring.

  1. Automatic protein structure solution from weak X-ray data

    Science.gov (United States)

    Skubák, Pavol; Pannu, Navraj S.

    2013-11-01

    Determining new protein structures from X-ray diffraction data at low resolution or with a weak anomalous signal is a difficult and often an impossible task. Here we propose a multivariate algorithm that simultaneously combines the structure determination steps. In tests on over 140 real data sets from the protein data bank, we show that this combined approach can automatically build models where current algorithms fail, including an anisotropically diffracting 3.88 Å RNA polymerase II data set. The method seamlessly automates the process, is ideal for non-specialists and provides a mathematical framework for successfully combining various sources of information in image processing.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yennawar, Hemant [Pennsylvania State University, 8 Althouse Laboratory, University Park, PA 16802 (United States); Møller, Magda [Cornell High Energy Synchrotron Source, Ithaca, NY 14853 (United States); University of Copenhagen, DK-2100 Copenhagen (Denmark); Gillilan, Richard [Cornell High Energy Synchrotron Source, Ithaca, NY 14853 (United States); Yennawar, Neela, E-mail: nhy1@psu.edu [Pennsylvania State University, 8 Althouse Laboratory, University Park, PA 16802 (United States)

    2011-05-01

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

  3. Neutron and X-ray diffraction from modulated structures

    International Nuclear Information System (INIS)

    Harris, P.

    1994-07-01

    This thesis describes X-ray and neutron scattering experiments performed on two examples of modulated structures. After an introduction to the subject of modulated structures, the thesis is divided in three parts. A single crystal elastic neutron scattering experiment between 4.2 and 115 Κ has been performed and four-circle X-ray data have been collected at 8 Κ for the monoclinic low-temperature phase of the layered perovskite PAMC. The results from the neutron scattering experiment indicate that magnetoelastic effects influence the ordering of the crystal. The X-ray experiments have made it possible to determine the crystal structure in the low-temperature phase. The superspace group is P2 1 /b(β-30)Os, with β = 1/3. A small-angle neutron scattering experiment has been performed on the magnetic structure of manganese silicide. When a magnetic field is applied, the modulation vectors turn towards the field direction, showing domain growth and diverging peak widths as they approach the field direction. Phase 'A' is established to have the modulation vectors directed perpendicular to the field direction. Cooling in zero field shows increasing peak widths at low temperatures, indicating a lock-in transition below the lowest reached temperature. To be able to analyse the data of the magnetic order in MnSi, and analytical calculation of the three dimensional resolution function for a small-angle neutron scattering spectrometer has been performed. The calculation is done by application of a combination of phase space analysis and Gaussian approximations for the neutron distribution as well as for the transmission functions of the different apertures. A finite mosaic spread of the crystal and finite correlation widths of the Bragg reflections have been included in the cross section. (au) (3 tabs., 48 ills., 100 refs.)

  4. An efficient synthesis, X-ray and spectral characterization of ...

    Indian Academy of Sciences (India)

    -thiazolidin-2,4-dione derivatives containing biphenyl ring system derivatised with the tetrazole (9), 1,2,4-triazoles (16), and 1,3,4- oxadiazole 17, 18. The single crystal X-ray analysis of one of the compounds 9 is also described as part of the.

  5. Acemetacin cocrystal structures by powder X-ray diffraction

    Science.gov (United States)

    Bolla, Geetha

    2017-01-01

    Cocrystals of acemetacin drug (ACM) with nicotinamide (NAM), p-aminobenzoic acid (PABA), valerolactam (VLM) and 2-pyridone (2HP) were prepared by melt crystallization and their X-ray crystal structures determined by high-resolution powder X-ray diffraction. The powerful technique of structure determination from powder data (SDPD) provided details of molecular packing and hydrogen bonding in pharmaceutical cocrystals of acemetacin. ACM–NAM occurs in anhydrate and hydrate forms, whereas the other structures crystallized in a single crystalline form. The carboxylic acid group of ACM forms theacid–amide dimer three-point synthon R 3 2(9)R 2 2(8)R 3 2(9) with three different syn amides (VLM, 2HP and caprolactam). The conformations of the ACM molecule observed in the crystal structures differ mainly in the mutual orientation of chlorobenzene fragment and the neighboring methyl group, being anti (type I) or syn (type II). ACM hydrate, ACM—NAM, ACM–NAM-hydrate and the piperazine salt of ACM exhibit the type I conformation, whereas ACM polymorphs and other cocrystals adopt the ACM type II conformation. Hydrogen-bond interactions in all the crystal structures were quantified by calculating their molecular electrostatic potential (MEP) surfaces. Hirshfeld surface analysis of the cocrystal surfaces shows that about 50% of the contribution is due to a combination of strong and weak O⋯H, N⋯H, Cl⋯H and C⋯H interactions. The physicochemical properties of these cocrystals are under study. PMID:28512568

  6. Acemetacin cocrystal structures by powder X-ray diffraction

    Directory of Open Access Journals (Sweden)

    Geetha Bolla

    2017-05-01

    Full Text Available Cocrystals of acemetacin drug (ACM with nicotinamide (NAM, p-aminobenzoic acid (PABA, valerolactam (VLM and 2-pyridone (2HP were prepared by melt crystallization and their X-ray crystal structures determined by high-resolution powder X-ray diffraction. The powerful technique of structure determination from powder data (SDPD provided details of molecular packing and hydrogen bonding in pharmaceutical cocrystals of acemetacin. ACM–NAM occurs in anhydrate and hydrate forms, whereas the other structures crystallized in a single crystalline form. The carboxylic acid group of ACM forms theacid–amide dimer three-point synthon R32(9R22(8R32(9 with three different syn amides (VLM, 2HP and caprolactam. The conformations of the ACM molecule observed in the crystal structures differ mainly in the mutual orientation of chlorobenzene fragment and the neighboring methyl group, being anti (type I or syn (type II. ACM hydrate, ACM—NAM, ACM–NAM-hydrate and the piperazine salt of ACM exhibit the type I conformation, whereas ACM polymorphs and other cocrystals adopt the ACM type II conformation. Hydrogen-bond interactions in all the crystal structures were quantified by calculating their molecular electrostatic potential (MEP surfaces. Hirshfeld surface analysis of the cocrystal surfaces shows that about 50% of the contribution is due to a combination of strong and weak O...H, N...H, Cl...H and C...H interactions. The physicochemical properties of these cocrystals are under study.

  7. Structure determination of spider silk from X-ray images

    Energy Technology Data Exchange (ETDEWEB)

    Ulrich, Stephan; Zippelius, Annette [Universitaet Goettingen, Institut fuer Theoretische Physik (Germany); Meling, Martin [Max-Planck-Institut fuer biophysikalische Chemie, Goettingen (Germany); Glisovic, Anja; Salditt, Tim [Universitaet Goettingen, Institut fuer Roentgenphysik (Germany)

    2008-07-01

    Spider silk consists of interconnected crystallites, which are typically aligned along the fiber axis. We present a method to systematically determine the structure of these crystallites. Hereby we introduce a model that calculates the scattering function G(q) which is fitted to the measured X-ray image (silk from nephila clavipes). With it, the crystallites' size, the constitution and dimensions of their unit cell, as well as their tilt with respect to the fiber axis is identified, and furthermore the effect of coherent scattering from different crystallites is investigated. The shown methods and the presented model can easily be generalized to a wide class of composite materials.

  8. Status and limitations of multilayer X-ray interference structures

    International Nuclear Information System (INIS)

    Kortright, J.B.

    1996-01-01

    Trends in the performance of x-ray multilayer interference structures with periods ranging from 9 to 130 (angstrom) are reviewed. Analysis of near-normal incidence reflectance data vs photon energy reveals that the effective interface with σ in a static Debye-Waller model, describing interdiffusion and roughness, decreases as the multilayer period decreases, and reaches a lower limit of roughly 2 (angstrom). Specular reflectance and diffuse scattering from uncoated and multilayer-coated substrates having different roughness suggest that this lower limit results largely from substrate roughness. The increase in interface width with period thus results from increasing roughness of interdiffusion as the layer thickness increases

  9. X-ray structure determination and deuteration of nattokinase

    International Nuclear Information System (INIS)

    Yanagisawa, Yasuhide; Chatake, Toshiyuki; Naito, Sawa; Ohsugi, Tadanori; Yatagai, Chieko; Sumi, Hiroyuki; Kawaguchi, Akio; Chiba-Kamosida, Kaori; Ogawa, Megumi; Adachi, Tatsumi; Morimoto, Yukio

    2013-01-01

    X-ray structure determination and deuteration of nattokinase were performed to facilitate neutron crystallographic analysis. Nattokinase (NK) is a strong fibrinolytic enzyme, which is produced in abundance by Bacillus subtilis natto. Although NK is a member of the subtilisin family, it displays different substrate specificity when compared with other subtilisins. The results of molecular simulations predict that hydrogen arrangements around Ser221 at the active site probably account for the substrate specificity of NK. Therefore, neutron crystallographic analysis should provide valuable information that reveals the enzymatic mechanism of NK. In this report, the X-ray structure of the non-hydrogen form of undeuterated NK was determined, and the preparation of deuterated NK was successfully achieved. The non-hydrogen NK structure was determined at 1.74 Å resolution. The three-dimensional structures of NK and subtilisin E from Bacillus subtilis DB104 are near identical. Deuteration of NK was carried out by cultivating Bacillus subtilis natto in deuterated medium. The D 2 O resistant strain of Bacillus subtilis natto was obtained by successive cultivation rounds, in which the concentration of D 2 O in the medium was gradually increased. NK was purified from the culture medium and its activity was confirmed by the fibrin plate method. The results lay the framework for neutron protein crystallography analysis

  10. X-ray structure determination and deuteration of nattokinase

    Energy Technology Data Exchange (ETDEWEB)

    Yanagisawa, Yasuhide [Chiba Institute of Science, 15-8 Shiomi-cho, Cho-shi, Chiba 288-025 (Japan); Chatake, Toshiyuki [Kyoto University, Asashironishi 2, Kumatori, Osaka 590-0494 (Japan); Naito, Sawa; Ohsugi, Tadanori; Yatagai, Chieko; Sumi, Hiroyuki [Kurashiki University of Science and the Arts, 2640 Nishinoura, Tsurajima-cho, Kurashiki, Okayama 712-8505 (Japan); Kawaguchi, Akio [Kyoto University, Asashironishi 2, Kumatori, Osaka 590-0494 (Japan); Chiba-Kamosida, Kaori [Nippon Advanced Technology Co. Ltd, J-PARC, 2-4 Shirane Shirakata, Tokai, Ibaraki 319-1195 (Japan); Ogawa, Megumi; Adachi, Tatsumi [Chiba Institute of Science, 15-8 Shiomi-cho, Cho-shi, Chiba 288-025 (Japan); Morimoto, Yukio [Kyoto University, Asashironishi 2, Kumatori, Osaka 590-0494 (Japan)

    2013-11-01

    X-ray structure determination and deuteration of nattokinase were performed to facilitate neutron crystallographic analysis. Nattokinase (NK) is a strong fibrinolytic enzyme, which is produced in abundance by Bacillus subtilis natto. Although NK is a member of the subtilisin family, it displays different substrate specificity when compared with other subtilisins. The results of molecular simulations predict that hydrogen arrangements around Ser221 at the active site probably account for the substrate specificity of NK. Therefore, neutron crystallographic analysis should provide valuable information that reveals the enzymatic mechanism of NK. In this report, the X-ray structure of the non-hydrogen form of undeuterated NK was determined, and the preparation of deuterated NK was successfully achieved. The non-hydrogen NK structure was determined at 1.74 Å resolution. The three-dimensional structures of NK and subtilisin E from Bacillus subtilis DB104 are near identical. Deuteration of NK was carried out by cultivating Bacillus subtilis natto in deuterated medium. The D{sub 2}O resistant strain of Bacillus subtilis natto was obtained by successive cultivation rounds, in which the concentration of D{sub 2}O in the medium was gradually increased. NK was purified from the culture medium and its activity was confirmed by the fibrin plate method. The results lay the framework for neutron protein crystallography analysis.

  11. Quantitative x-ray structure determination of superlattices and interfaces

    International Nuclear Information System (INIS)

    Schuller, I.K.; Fullerton, E.E.

    1990-01-01

    This paper presents a general procedure for quantitative structural refinement of superlattice structures. To analyze a wide range of superlattices, the authors have derived a general kinematical diffraction formula that includes random, continuous and discrete fluctuations from the average structure. By implementing a non-linear fitting algorithm to fit the entire x-ray diffraction profile, refined parameters that describe the average superlattice structure, and deviations from this average are obtained. The structural refinement procedure is applied to a crystalline/crystalline Mo/Ni superlattices and crystalline/amorphous Pb/Ge superlattices. Roughness introduced artificially during growth in Mo/Ni superlattices is shown to be accurately reproduced by the refinement

  12. X-ray synthesis of nickel-gold composite nanoparticles

    International Nuclear Information System (INIS)

    Kim, Chong-Cook; Wang Changhai; Yang, Y.-C.; Hwu, Y.K.; Seol, Seung-Kwon; Kwon, Yong-Bum; Chen, C.-H.; Liou, Huey-Wen; Lin, H.-M.; Margaritondo, Giorgio; Je, Jung-Ho

    2006-01-01

    We developed a novel approach to prepare Ni-Au composite nanoparticles using synchrotron radiation X-rays. Ni-Au particles dispersed in aqueous solutions were synthesized with two different irradiation strategies. The first is by exposing to X-rays a mixed electroless solution of Ni and Au at two different temperatures, trying to nucleate Ni nanoparticles homogeneously at room temperature and to deposit Au subsequently on them at the high temperature of 70 deg. C. The second strategy is to change the pH value of the mixed solution, directly leading to the formation of Ni-Au nanoparticles. In both cases, the Ni-Au composite nanoparticles were successfully formed, as confirmed by the observed ferromagnetic behavior and by the evolution of the Au surface plasmon resonance band

  13. Phosphoramidates: synthesis, spectroscopy, and X-ray crystallography

    Czech Academy of Sciences Publication Activity Database

    Shariatinia, Z.; Sohrabi, M.; Yousefi, M.; Kovaľ, Tomáš; Dušek, Michal

    2012-01-01

    Roč. 23, č. 5 (2012), s. 478-485 ISSN 1042-7163 Grant - others:AV ČR(CZ) AP0701 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : phosphoramidates * X-ray diffraction * spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.577, year: 2012

  14. Novel organophosphorus compounds; synthesis, spectroscopy and X-ray crystallography

    Czech Academy of Sciences Publication Activity Database

    Shariatinia, Z.; Sohrabi, M.; Yousefi, M.; Kovaľ, Tomáš; Dušek, Michal

    2012-01-01

    Roč. 11, č. 2 (2012), s. 125-133 ISSN 1024-1221 Grant - others:AV ČR(CZ) AP0701 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : organophosphorus compounds * NMR * X-ray crystallography * hydrogen bond Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.686, year: 2012

  15. Design of novel HIV-1 protease inhibitors incorporating isophthalamide-derived P2-P3 ligands: Synthesis, biological evaluation and X-ray structural studies of inhibitor-HIV-1 protease complex

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Arun K.; Brindisi, Margherita; Nyalapatla, Prasanth R.; Takayama, Jun; Ella-Menye, Jean-Rene; Yashchuk, Sofiya; Agniswamy, Johnson; Wang, Yuan-Fang; Aoki, Manabu; Amano, Masayuki; Weber, Irene T.; Mitsuya, Hiroaki

    2017-10-01

    Based upon molecular insights from the X-ray structures of inhibitor-bound HIV-1 protease complexes, we have designed a series of isophthalamide-derived inhibitors incorporating substituted pyrrolidines, piperidines and thiazolidines as P2-P3 ligands for specific interactions in the S2-S3 extended site. Compound 4b has shown an enzyme Ki of 0.025 nM and antiviral IC50 of 69 nM. An X-ray crystal structure of inhibitor 4b-HIV-1 protease complex was determined at 1.33 Å resolution. We have also determined X-ray structure of 3b-bound HIV-1 protease at 1.27 Å resolution. These structures revealed important molecular insight into the inhibitor–HIV-1 protease interactions in the active site.

  16. Synthesis, NMR characterization, X-ray crystal structure of Co(II) Ni(II) and Cu(II) complexes of a pyridine containing self-assembling

    International Nuclear Information System (INIS)

    Ranjbar, M.; Taghavipour, M.; Moghimi, A.; Aghabozorg, H.

    2002-01-01

    In the recent years, the self-assembling systems have been attracted chemists. The intermolecular bond in such systems mainly consists of ion pairing and hydrogen bonding [1,2]. The reaction between self-assembling system liquid LH 2 (py dc=2,6-pyridinedicarboxylic acid and py da=2,6- pyridine diamin) with cobalt (II) nitrate, nickel (II) chloride, and copper (II) acetate in water leads to the formation of self- assemble coordination complexes, [py da.H] 2 [M(py dc) 2 ]. H 2 O, M=Co(II),Ni(II), and Cu(II). The characterization was performed using elemental analysis, ESI mass spectroscopy, 1 H and 13 C NMR and X-ray crystallography. The crystal systems are monoclinic with space group P2 1 /n and four molecules per unit cell. These complexes shows 13 C NMR resonances of cationic counter ion [(py dc,H)] + in DMSO- d 6 but no signal corresponding to the two coordinated ligands [py dc] 2- The metal atoms are six-coordinated with a distorted octahedral geometry. The two [py de] 2- units are almost perpendicular to each other

  17. Dinuclear NHC-palladium complexes containing phosphine spacers: synthesis, X-ray structures and their catalytic activities towards the Hiyama coupling reaction.

    Science.gov (United States)

    Yang, Jin; Li, Pinhua; Zhang, Yicheng; Wang, Lei

    2014-05-21

    Six dinuclear N-heterocyclic carbene (NHC) palladium complexes, [PdCl2(IMes)]2(μ-dppe) (1), [PdCl2(IPr)]2(μ-dppe) (2), [PdCl2(IMes)]2(μ-dppb) (3), [PdCl2(IPr)]2(μ-dppb) (4), [PdCl2(IMes)]2(μ-dpph) (5), and [PdCl2(IPr)]2(μ-dpph) (6) [IMes = N,N'-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene; IPr = N,N'-bis-(2,6-di(iso-propyl)phenyl)imidazol-2-ylidene; dppe = 1,2-bis(diphenylphosphino)ethane, dppb = 1,4-bis(diphenylphosphino)butane; and dpph = 1,6-bis(diphenylphosphino)hexane], have been synthesized through bridge-cleavage reactions of chloro-bridged dimeric compounds, [Pd(μ-Cl)(Cl)(NHC)]2, with the corresponding diphosphine ligands. The obtained compounds were fully characterized by (1)H NMR, (13)C NMR and (31)P NMR spectroscopy, FT-IR, elemental analysis and single-crystal X-ray crystallography. Moreover, further explorations of the catalytic potential of the dinuclear carbene palladium complexes as catalysts for the Pd-catalyzed transformations have been performed under microwave irradiation conditions, and the complexes exhibited moderate to good catalytic activity in the Hiyama coupling reaction of trimethoxyphenylsilane with aryl chlorides.

  18. DNA binding, antioxidant, cytotoxicity (MTT, lactate dehydrogenase, NO), and cellular uptake studies of structurally different nickel(II) thiosemicarbazone complexes: synthesis, spectroscopy, electrochemistry, and X-ray crystallography.

    Science.gov (United States)

    Prabhakaran, R; Kalaivani, P; Huang, R; Poornima, P; Vijaya Padma, V; Dallemer, F; Natarajan, K

    2013-02-01

    Three new nickel(II) thiosemicarbazone complexes have been synthesized and characterized by analytical, spectral, and single-crystal X-ray diffraction studies. In complex 1, the ligand 2-hydroxy-1-naphthaldehydethiosemicarbazone coordinated as a monobasic tridentate donor, whereas in complexes 2 and 3, the ligands salicylaldehyde-4(N)-ethylthiosemicarbazone and 2-hydroxy-1-naphthaldehyde-4(N)-ethylthiosemicarbazone coordinated as a dibasic tridentate donor. The DNA binding ability of the complexes in calf thymus DNA was explored by absorption and emission titration experiments. The antioxidant property of the new complexes was evaluated to test their free-radical scavenging ability. In vitro cytotoxicity assays were performed for the new complexes in A549 and HepG2 cell lines. The new compounds overcome cisplatin resistance in the A549 cell line and they were also active in the HepG2 cell line. The cellular uptake study showed the accumulation of the complexes in tumor cells depended on the nature of the ligand attached to the nickel ion.

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

    International Nuclear Information System (INIS)

    Ericson, Agneta.

    1989-01-01

    The thesis presents extended X-ray absorption fine structure, EXAFS, and large angle X-ray scattering, LAXS, techniques; instrumentation, data collection and reduction, and applications. These techniques have been used to determine the structures of magnesium halides and organomagnesium halides in diethyl ether and tetrahydrofuran solution. The iodides were used for the LAXS measurements and Br K edge EXAFS data were collected for the corresponding bromides. Two different complexes are present in the diethyl ether solution of magnesium iodide; a polymeric chain-type structure where magnesium is tetrahedrally coordinated, as well as dimeric complex with octahedrally coordinated magnesium. Solvated MgI + is the dominating species in tetrahydrofuran solution. The organomagnesium halides are present in diethyl ether solution as both solvated monomeric and dimeric complexes. Magnesium coordinates a halide ion, an alkyl or aryl group and four solvent molecules octahedrally in the monomeric complex. In the dimeric complex magnesium is octahedrally coordinated by two bridging halide ions, an alkyl or aryl group and three solvent molecules. The distribution of monomeric and dimeric complexes in various solutions are given by a dimerisation constant, K dl . The results indicate that the Schlenk equilibrium is present in these solutions, however, in an extended form. In diethyl ether solution, where MgX 2 does not dissociate, no MgX 2 complex and thereby no Schlenk equilibrium has been observed. In tetrahydrofuran solution MgI 2 has dissociated into mainly MgI + and I - . This indicates that the concentration of MgI 2 is low and that the Schlenk equilibrium should be expanded even further to include the dissociation equilibrium of the magnesium halide. In the thesis Fe K edge EXAFS data collected for the semireduced form of protein A of methane monooxygenase from Methylococcus capsulatus, are also presented. (139 refs.)

  20. Electronic structure of nanoscale Cu/Pt alloys: A combined X-ray diffraction and X-ray absorption investigations

    International Nuclear Information System (INIS)

    Chen Xing; Chu Wangsheng; Cai Quan; Xia Dingguo; Wu Zhonghua; Wu Ziyu

    2006-01-01

    PVP-protected Cu/Pt clusters were prepared by glycol/water reduction method and characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD) and absorption spectra. TEM and XRD analysis show that the Cu/Pt clusters with different molar ratio have fcc structure with particle size of about 4 nm, while the lattice parameters in these clusters reduce with increasing Cu concentration. From the X-ray absorption near edge structure (XANES) at Cu-K edge and Pt-L 2,3 edge, we demonstrate that the d-electronic states of Cu and Pt are affected by the local environment as a function of Cu/Pt molar ratio. With increasing Cu concentration, Pt loses a fraction of 5d electrons and the hybridization between p- and d-states at Cu sites is enhanced

  1. Electronic structure of nanoscale Cu/Pt alloys: A combined X-ray diffraction and X-ray absorption investigations

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xing [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); Graduate School of the Chinese Academy of Sciences, 100864 Beijing (China); Chu Wangsheng [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); University of Science and Technology of China, Hefei, 230036 (China); Cai Quan [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); Graduate School of the Chinese Academy of Sciences, 100864 Beijing (China); Xia Dingguo [College of Environmental and Energy Engineering, Beijing University of Technology, 100022 Beijing (China); Wu Zhonghua [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); Wu Ziyu [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China) and National Center for Nanoscience and Technology (China)]. E-mail: wuzy@ihep.ac.cn

    2006-11-15

    PVP-protected Cu/Pt clusters were prepared by glycol/water reduction method and characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD) and absorption spectra. TEM and XRD analysis show that the Cu/Pt clusters with different molar ratio have fcc structure with particle size of about 4 nm, while the lattice parameters in these clusters reduce with increasing Cu concentration. From the X-ray absorption near edge structure (XANES) at Cu-K edge and Pt-L{sub 2,3} edge, we demonstrate that the d-electronic states of Cu and Pt are affected by the local environment as a function of Cu/Pt molar ratio. With increasing Cu concentration, Pt loses a fraction of 5d electrons and the hybridization between p- and d-states at Cu sites is enhanced.

  2. Native chemical ligation at Asx-Cys, Glx-Cys: chemical synthesis and high-resolution X-ray structure of ShK toxin by racemic protein crystallography.

    Science.gov (United States)

    Dang, Bobo; Kubota, Tomoya; Mandal, Kalyaneswar; Bezanilla, Francisco; Kent, Stephen B H

    2013-08-14

    We have re-examined the utility of native chemical ligation at -Gln/Glu-Cys- [Glx-Cys] and -Asn/Asp-Cys- [Asx-Cys] sites. Using the improved thioaryl catalyst 4-mercaptophenylacetic acid (MPAA), native chemical ligation could be performed at -Gln-Cys- and Asn-Cys- sites without side reactions. After optimization, ligation at a -Glu-Cys- site could also be used as a ligation site, with minimal levels of byproduct formation. However, -Asp-Cys- is not appropriate for use as a site for native chemical ligation because of formation of significant amounts of β-linked byproduct. The feasibility of native chemical ligation at -Gln-Cys- enabled a convergent total chemical synthesis of the enantiomeric forms of the ShK toxin protein molecule. The D-ShK protein molecule was ~50,000-fold less active in blocking the Kv1.3 channel than the L-ShK protein molecule. Racemic protein crystallography was used to obtain high-resolution X-ray diffraction data for ShK toxin. The structure was solved by direct methods and showed significant differences from the previously reported NMR structures in some regions of the ShK protein molecule.

  3. Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

    Science.gov (United States)

    Weisskopf, Martin C.; Hester, J. Jeff; Tennant, Allyn F.; Elsner, Ronald F.; Schulz, Norbert S.; Marshall, Herman L.; Karovska, Margarita; Nichols, Joy S.; Swartz, Douglas A.; Kolodziejczak, Jeffery J.

    2000-01-01

    The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced Charge Coupled Devices (CCD) Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.

  4. Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula.

    Science.gov (United States)

    Weisskopf; Hester; Tennant; Elsner; Schulz; Marshall; Karovska; Nichols; Swartz; Kolodziejczak; O'Dell

    2000-06-20

    The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.

  5. Reduction of nitro groups by ynamines; synthesis and x-ray crystal structure of n,n-diethyl-3,3a-dihydro-3-methylbenzofuro[3,2-c]isoxazole-3-carboxamide

    NARCIS (Netherlands)

    de Wit, A.D.; Trompenaars, W.P.; Reinhoudt, David; Harkema, Sybolt; van Hummel, G.J.

    1980-01-01

    3-Nitrobenzo[b]furan and 1-diethylaminopropyne react thermally at 5–10°C to give a 1:1 addition product ( ) in which one of the oxygen atoms of the nitro group is transferred to C-1 of the acetylene. The structure of the benzofuro[3,2-c]isoxazole ( ) has been determined by X-ray crystallography.

  6. Directional fine structure in absorption of white x rays: A tomographic interpretation

    International Nuclear Information System (INIS)

    Korecki, P.; Szymonski, M.; Tolkiehn, M.; Novikov, D. V.; Materlik, G.

    2006-01-01

    We discuss directional fine structure in absorption of white x rays for tomographic imaging of crystal structure at the atomic level. The interference between a direct x-ray beam and the secondary waves coherently scattered inside a specimen modifies the total wave field at the position of the absorbing atoms. For a white x-ray beam, the wave field variations cancel out by energy integration for all directions, except for the near forward scattering components, coinciding with the incident beam. Therefore, two-dimensional patterns of the angular-dependent fine structure in absorption of white x rays can be interpreted as real-space projections of atomic structure. In this work, we present a theory describing the directional fine structure in white x-ray absorption and a tomographic approach for crystal structure retrieval developed on its basis. The tomographic algorithm is applied to the experimental x-ray absorption data recorded for GaP crystals

  7. X-ray Structure of the Mature Ectodomain of Phogrin

    Energy Technology Data Exchange (ETDEWEB)

    Noguera, M. E. [National Univ. of Quilmes, Buenos Aires (Argentina); Primo, M. [Univ. of Buenos Aires (Argentina); Jakoncic, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Poskus, E. [Univ. of Buenos Aires (Argentina); Solimena, M. [Dresden Univ. of Technology and Max Planck Inst. of Molecular Cell Biology and Genetics (Germany); Ermacora, M. R. [National Univ. of Quilmes and Multidisciplinary Inst. of Cellular Biology, Buenos Aires (Argentina)

    2014-11-26

    Phogrin/IA-2β and ICA512/IA-2 are two paralogs receptor-type protein-tyrosine phosphatases (RPTP) that localize in secretory granules of various neuroendocrine cells. In pancreatic islet β-cells, they participate in the regulation of insulin secretion, ensuring proper granulogenesis, and β-cell proliferation. The role of their cytoplasmic tail has been partially unveiled, while that of their luminal region remains unclear. To advance the understanding of its structure–function relationship, the X-ray structure of the mature ectodomain of phogrin (ME phogrin) at pH 7.4 and 4.6 has been solved at 1.95- and 2.01-Å resolution, respectively. Likewise to the ME of ICA512, ME phogrin adopts a ferredoxin-like fold: a sheet of four antiparallel β-strands packed against two α-helices. Furthermore, sequence conservation among vertebrates, plants and insects suggests that the structural similarity extends to all the receptor family. Crystallized ME phogrin is monomeric, in agreement with solution studies but in striking contrast with the behavior of homodimeric ME ICA512. The structural details that may cause the quaternary structure differences are analyzed. The results provide a basis for building models of the overall orientation and oligomerization state of the receptor in biological membranes.

  8. X-ray structure determination and deuteration of nattokinase.

    Science.gov (United States)

    Yanagisawa, Yasuhide; Chatake, Toshiyuki; Naito, Sawa; Ohsugi, Tadanori; Yatagai, Chieko; Sumi, Hiroyuki; Kawaguchi, Akio; Chiba-Kamosida, Kaori; Ogawa, Megumi; Adachi, Tatsumi; Morimoto, Yukio

    2013-11-01

    Nattokinase (NK) is a strong fibrinolytic enzyme, which is produced in abundance by Bacillus subtilis natto. Although NK is a member of the subtilisin family, it displays different substrate specificity when compared with other subtilisins. The results of molecular simulations predict that hydrogen arrangements around Ser221 at the active site probably account for the substrate specificity of NK. Therefore, neutron crystallographic analysis should provide valuable information that reveals the enzymatic mechanism of NK. In this report, the X-ray structure of the non-hydrogen form of undeuterated NK was determined, and the preparation of deuterated NK was successfully achieved. The non-hydrogen NK structure was determined at 1.74 Å resolution. The three-dimensional structures of NK and subtilisin E from Bacillus subtilis DB104 are near identical. Deuteration of NK was carried out by cultivating Bacillus subtilis natto in deuterated medium. The D2O resistant strain of Bacillus subtilis natto was obtained by successive cultivation rounds, in which the concentration of D2O in the medium was gradually increased. NK was purified from the culture medium and its activity was confirmed by the fibrin plate method. The results lay the framework for neutron protein crystallography analysis.

  9. Fast synchrotron X-ray tomography study of the rod packing structures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xiaodan; Xia Chengjie; Sun Haohua; Wang Yujie [Department of Physics, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China)

    2013-06-18

    We present a fast synchrotron X-ray tomography study of the packing structures of rods under tapping. Utilizing the high flux of the X-rays generated from the third-generation synchrotron source, we can complete a tomography scan within several seconds, after which the three-dimensional (3D) packing structure can be obtained for the subsequent structural analysis. Due to the high-energy nature of the X-ray beam, special image processing steps including image phase-retrieval has been implemented. Overall, this study suggests the possibility of acquiring statistically significant static packing structures within a reasonable time scale using high-intensity X-ray sources.

  10. SYNTHESIS OF NEW NANO SCHIFF BASE COMPLEXES: X-RAY ...

    African Journals Online (AJOL)

    analyses were recorded on Perkin-Elmer Pyris Diamond model. ... measurements were made on a STOE IPDS 2T diffractometer with graphite monochromated ..... It was confirmed that by changing the solvent of the synthesis or.

  11. Synthesis and X-ray crystal structure of a novel organometallic (µ(3)-oxido)(µ(3)-imido) trinuclear iridium complex

    DEFF Research Database (Denmark)

    Schau-Magnussen, Magnus; Malcho, Phillip; Herbst, Konrad

    2011-01-01

    Reaction of the organometallic aqua ion [Cp*Ir(H(2)O)(3)](2+) with tert-butyl(trimethylsilyl)amine in acetone yielded a novel trinuclear (µ(3)-oxido)(µ(3)-imido)pentamethylcyclopentadienyliridium(iii) complex, [(Cp*Ir)(3)(O)(N(t)Bu)](2+). Single crystal structure analyses show the complex can be ...... that a trinuclear (µ(3)-oxido)(µ(3)-imido) transition metal complex has been structurally characterized....

  12. X-ray photoemission spectroscopy (XPS) and extended x-ray absorption fine structure (EXAFS) studies of silicate based glasses

    International Nuclear Information System (INIS)

    Karim, D.; Lam, D.J.

    1979-01-01

    The application of the x-ray photoemission spectroscopy (XPS) technique to study the electronic structure and bonding of heavy metal oxides in alkali- and alkali-earth-silicate glasses had been demonstrated. The bonding characteristics of the iron oxide and uranium oxide in sodium silicate glasses were deduced from the changes in the oxygen 1s levels and the heavy metal core levels. It is reasonable to expect that the effect of leaching on the heavy metal ions can be monitored using the appropriate core levels of these ions. To study the effect of leaching on the glass forming network, the valence band structure of the bridging and nonbridging oxygens in sodium silicate glasses were investigated. The measurement of extended x-ray absorption fine-structure (EXAFS) is a relatively new analytical technique for obtaining short range (<5 A) structural information around atoms of a selected species in both solid and fluid systems. Experiments have recently begun to establish the feasibility of using EXAFS to study the bonding of actinides in silicate glasses. Because of the ability of EXAFS to yield specific structural data even in complex multicomponent systems, it could prove to be an invaluable tool in understanding glass structure

  13. Synthesis and X-ray crystal structure determination of N-p-methylphenyl-4-benzoyl-3,4-diphenyl-2-azetidinone

    Czech Academy of Sciences Publication Activity Database

    Kabak, M.; Senöz, H.; Elmali, A.; Adar, V.; Svoboda, I.; Dušek, Michal; Fejfarová, Karla

    2010-01-01

    Roč. 55, č. 7 (2010), s. 1220-1222 ISSN 1063-7745 Institutional research plan: CEZ:AV0Z10100521 Keywords : molecular structure * carbon * azetidione Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.644, year: 2010

  14. Synthesis, X-ray structure, and hydrolytic chemistry of the high potent antiviral polyniobotungstate A-[alpha]-[Si2Nb6W18O77]8–

    Science.gov (United States)

    Gyu-Shik Kim; Huadong Zeng; Jeffrey T. Rhule; Ira A. Weinstock; Craig L. Hill

    1999-01-01

    Potently antiviral polyniobotungstates have been structurally characterized; the dimer A-[alpha]-[Si2Nb6W18O77]8– cleaves cleanly to the monomer A-[alpha]-[SiNb3W9O40]7– within 1 min in aqueous solution buffered at physiological (neutral) pH establishing that the monomer and not the dimer is pharmacologically relevant.

  15. X-ray structural analysis of plasma sprayed europium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Gorshkov, B.N.; Loskutov, V.S.; Gavrish, A.A.; Shakh, G.E.

    1981-12-01

    An X-ray structure microanalysis is made for europium oxide powder produced by sintering and plasmic spheroidization for plasma spraying. The technique of concern is shown not to alter chemical composition of the powder. It is stated that a rise in the plasma jet enthalpy while spraying does not result in dissociation of europium oxide and its interaction with the plasma flux. The coating (to 15.2 kWxs/g) is found to have only a high-temperature (monoclinic) europium oxide phase and there appears a low-temperature (cubic) phase with a subsequent increase in the enthalpy. The plasma jet enthalpy increasing the grain size and the crystal lattice c parameter of the sprayed europium oxide are shown to decrease; the a parameter reduces with an enthalpy growth to 16.2 kW s/g and then smoothly increases with the enthalpy further growth. It is noticed that the europium oxide coating does not interact with an aluminium D16 alloy substrate.

  16. Synthesis of new nano Schiff base complexes: X-ray crystallography ...

    African Journals Online (AJOL)

    This study presents synthesis and characterization of new nano uranyl Schiff base complexes. Electrochemistry of these complexes showed a quasireversible redox reaction without any successive reactions. Furthermore, X-ray crystallography exhibited that beside the coordination of tetradentate Schiff base, one solvent ...

  17. Ruthenium(II) bipyridine complexes bearing quinoline-azoimine (NN'N″) tridentate ligands: synthesis, spectral characterization, electrochemical properties and single-crystal X-ray structure analysis.

    Science.gov (United States)

    Al-Noaimi, Mousa; Abdel-Rahman, Obadah S; Fasfous, Ismail I; El-khateeb, Mohammad; Awwadi, Firas F; Warad, Ismail

    2014-05-05

    Four octahedral ruthenium(II) azoimine-quinoline complexes having the general molecular formula [Ru(II)(L-Y)(bpy)Cl](PF6) {L-Y=YC6H4N=NC(COCH3)=NC9H6N, Y=H (1), CH3 (2), Br (3), NO2 (4) and bpy=2,2'-bipyrdine} were synthesized. The azoimine-quinoline based ligands behave as NN'N″ tridentate donors and coordinated to ruthenium via azo-N', imine-N' and quinolone-N″ nitrogen atoms. The composition of the complexes has been established by elemental analysis, spectral methods (FT-IR, electronic, (1)H NMR, UV/Vis and electrochemical (cyclic voltammetry) techniques. The crystal structure of complex 1 is reported. The Ru(II) oxidation state is greatly stabilized by the novel tridentate ligands, showing Ru(III/II) couples ranging from 0.93-1.27 V vs. Cp2Fe/Cp2Fe(+). The absorption spectrum of 1 in dichloromethane was modeled by time-dependent density functional theory (TD-DFT). Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Microanalysis of iron oxidation state in iron oxides using X Ray Absorption Near Edge Structure (XANES)

    Science.gov (United States)

    Sutton, S. R.; Delaney, J.; Bajt, S.; Rivers, M. L.; Smith, J. V.

    1993-01-01

    An exploratory application of x ray absorption near edge structure (XANES) analysis using the synchrotron x ray microprobe was undertaken to obtain Fe XANES spectra on individual sub-millimeter grains in conventional polished sections. The experiments concentrated on determinations of Fe valence in a suite of iron oxide minerals for which independent estimates of the iron speciation could be made by electron microprobe analysis and x ray diffraction.

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

    DEFF Research Database (Denmark)

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

    1979-01-01

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

  20. Discovery of novel inhibitors for DHODH via virtual screening and X-ray crystallographic structures

    Energy Technology Data Exchange (ETDEWEB)

    McLean, Larry R.; Zhang, Ying; Degnen, William; Peppard, Jane; Cabel, Dasha; Zou, Chao; Tsay, Joseph T.; Subramaniam, Arun; Vaz, Roy J.; Li, Yi (Sanofi)

    2010-10-28

    Amino-benzoic acid derivatives 1-4 were found to be inhibitors for DHODH by virtual screening, biochemical, and X-ray crystallographic studies. X-ray structures showed that 1 and 2 bind to DHODH as predicted by virtual screening, but 3 and 4 were found to be structurally different from the corresponding compounds initially identified by virtual screening.

  1. Structure and dynamics in liquid water from x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Wernet, Philippe

    2009-01-01

    Oxygen K-edge x-ray absorption spectra of water are discussed. The spectra of gas-phase water, liquid water and ice illustrate the sensitivity of oxygen K-edge x-ray absorption spectroscopy to hydrogen bonding in water. Transmission mode spectra of amorphous and crystalline ice are compared to x-ray Raman spectra of ice. The good agreement consolidates the experimental spectrum of crystalline ice and represents an incentive for theoretical calculations of the oxygen K-edge absorption spectrum of crystalline ice. Time-resolved infrared-pump and x-ray absorption probe results are finally discussed in the light of this structural interpretation.

  2. X-ray CT analysis of pore structure in sand

    Science.gov (United States)

    Mukunoki, Toshifumi; Miyata, Yoshihisa; Mikami, Kazuaki; Shiota, Erika

    2016-06-01

    The development of microfocused X-ray computed tomography (CT) devices enables digital imaging analysis at the pore scale. The applications of these devices are diverse in soil mechanics, geotechnical and geoenvironmental engineering, petroleum engineering, and agricultural engineering. In particular, the imaging of the pore space in porous media has contributed to numerical simulations for single-phase and multiphase flows or contaminant transport through the pore structure as three-dimensional image data. These obtained results are affected by the pore diameter; therefore, it is necessary to verify the image preprocessing for the image analysis and to validate the pore diameters obtained from the CT image data. Moreover, it is meaningful to produce the physical parameters in a representative element volume (REV) and significant to define the dimension of the REV. This paper describes the underlying method of image processing and analysis and discusses the physical properties of Toyoura sand for the verification of the image analysis based on the definition of the REV. On the basis of the obtained verification results, a pore-diameter analysis can be conducted and validated by a comparison with the experimental work and image analysis. The pore diameter is deduced from Young-Laplace's law and a water retention test for the drainage process. The results from previous study and perforated-pore diameter originally proposed in this study, called the voxel-percolation method (VPM), are compared in this paper. In addition, the limitations of the REV, the definition of the pore diameter, and the effectiveness of the VPM for an assessment of the pore diameter are discussed.

  3. Deficiency in plasma protein synthesis caused by x-ray-induced lethal albino alleles in mouse

    International Nuclear Information System (INIS)

    Garland, R.C.; Satrustegui, J.; Gluecksohn-Waelsch, S.; Cori, C.F.

    1976-01-01

    Plasma protein synthesis was studied in mice bearing x-ray induced lethal mutations at the albino locus. Newborn albino mutants showed a decrease in each of the three principal plasma proteins, albumin, α-fetoprotein, and transferrin, when compared with colored littermate controls. Incorporation of [ 14 C] leucine into plasma proteins of the newborn albinos 30 min after injection was only 1 / 5 that of the controls, but incorporation into total liver protein was only slightly diminished. Incorporation of [ 14 C] leucine into an albumin fraction obtained by immunoprecipitation from livers incubated in vitro in an amino acid mixture was also strongly diminished. Thus, the liver of 18-day-old albino fetuses incorporated into this fraction 1 / 3 and that of newborn albinos 1 / 8 as much as the controls, but in both cases the incorporation into total liver protein was only 25 percent less than in the respective controls. These results indicate that the rather severe structural abnormalities observed in the mutants in the endoplasmic reticulum and the Golgi apparatus are not associated with a general deficiency of hepatic protein synthesis. Instead the data from this and previous work show that the progressive deficiency from fetal life to birth involves certain specific proteins represented by several perinatally developing enzymes and by plasma proteins. It is suggested that the mutational effects observed in these mice are due to deletions involving regulatory rather than structural genes at or near the albino locus

  4. Hard X-ray irradiation of cosmic silicate analogs: structural evolution and astrophysical implications

    Science.gov (United States)

    Gavilan, L.; Jäger, C.; Simionovici, A.; Lemaire, J. L.; Sabri, T.; Foy, E.; Yagoubi, S.; Henning, T.; Salomon, D.; Martinez-Criado, G.

    2016-03-01

    Context. Protoplanetary disks, interstellar clouds, and active galactic nuclei contain X-ray-dominated regions. X-rays interact with the dust and gas present in such environments. While a few laboratory X-ray irradiation experiments have been performed on ices, X-ray irradiation experiments on bare cosmic dust analogs have been scarce up to now. Aims: Our goal is to study the effects of hard X-rays on cosmic dust analogs via in situ X-ray diffraction. By using a hard X-ray synchrotron nanobeam, we seek to simulate cumulative X-ray exposure on dust grains during their lifetime in these astrophysical environments and provide an upper limit on the effect of hard X-rays on dust grain structure. Methods: We prepared enstatite (MgSiO3) nanograins, which are analogs to cosmic silicates, via the melting-quenching technique. These amorphous grains were then annealed to obtain polycrystalline grains. These were characterized via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) before irradiation. Powder samples were prepared in X-ray transparent substrates and were irradiated with hard X-rays nanobeams (29.4 keV) provided by beamline ID16B of the European Synchrotron Radiation Facility (Grenoble). X-ray diffraction images were recorded in transmission mode, and the ensuing diffractograms were analyzed as a function of the total X-ray exposure time. Results: We detected the amorphization of polycrystalline silicates embedded in an organic matrix after an accumulated X-ray exposure of 6.4 × 1027 eV cm-2. Pure crystalline silicate grains (without resin) do not exhibit amorphization. None of the amorphous silicate samples (pure and embedded in resin) underwent crystallization. We analyze the evolution of the polycrystalline sample embedded in an organic matrix as a function of X-ray exposure. Conclusions: Loss of diffraction peak intensity, peak broadening, and the disappearance of discrete spots and arcs reveal the amorphization

  5. X-ray tomography investigations on pebble bed structures

    International Nuclear Information System (INIS)

    Reimann, J.; Rolli, R.; Pieritz, R.A.; Ferrero, C.; Di Michiel, M.

    2007-01-01

    Granular materials (pebbles) are used in present ceramic breeder blankets both for the ceramic breeder material and beryllium. The thermal-mechanical behaviour of these pebble beds strongly depends on the arrangement of the pebbles in the bed, their contacts and contact surfaces with other pebbles and with walls. The influence of these quantities is most pronounced for beryllium pebble beds because of the large thermal conductivity ratio of beryllium to helium gas atmosphere. At present, the data base for the pebble bed thermal conductivity (k) and heat transfer coefficient (h) is quite limited for compressed beds and significant discrepancies exist in respect to h. The detailed knowledge of the pebble bed topology is, therefore, essential to better understand the heat transfer mechanisms. In the present work, results from detailed X-ray tomography investigations are reported on pebble topology in i) the pebble bed bulk (which is relevant for k), and ii) the region close to walls with thicknesses of several pebble diameters (relevant for h). At Forschungszentrum Karlsruhe, pebble beds consisting of aluminium spheres with diameters of 2.3 and 5 mm, respectively, (simulating the blanket relevant 1 mm beryllium pebbles), were uniaxially compressed at different pressure levels. High resolution three-dimensional microtomography (MT) experiments were subsequently performed at the European Synchrotron Radiation Facility, Grenoble. Radial and axial void fraction distributions were found to be oscillatory next to the walls and non-oscillatory in the bulk. For non-compressed pebble beds, the bulk void fraction is fairly constant; for compressed beds, a gradient exists along the compression axis. In the bulk, the angular distribution of pebble contacts was found to be fairly constant, indicating that no regular packing structure is induced. In the wall region, the pebble layer touching the wall is composed of zones with hexagonal structures as shown clearly by MT images. This

  6. Excited state electron and energy relays in supramolecular dinuclear complexes revealed by ultrafast optical and X-ray transient absorption spectroscopy† †Electronic supplementary information (ESI) available: Synthesis schemes, experimental methods, NMR spectra, X-ray crystallographic information, emission spectra, cyclic voltammetry, electronic structure calculations, data analysis and numerical methods, and other additional figures. CCDC 1561879. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04055e

    Science.gov (United States)

    Kohler, Lars; Hadt, Ryan G.; Zhang, Xiaoyi; Liu, Cunming

    2017-01-01

    The kinetics of photoinduced electron and energy transfer in a family of tetrapyridophenazine-bridged heteroleptic homo- and heterodinuclear copper(i) bis(phenanthroline)/ruthenium(ii) polypyridyl complexes were studied using ultrafast optical and multi-edge X-ray transient absorption spectroscopies. This work combines the synthesis of heterodinuclear Cu(i)–Ru(ii) analogs of the homodinuclear Cu(i)–Cu(i) targets with spectroscopic analysis and electronic structure calculations to first disentangle the dynamics at individual metal sites by taking advantage of the element and site specificity of X-ray absorption and theoretical methods. The excited state dynamical models developed for the heterodinuclear complexes are then applied to model the more challenging homodinuclear complexes. These results suggest that both intermetallic charge and energy transfer can be observed in an asymmetric dinuclear copper complex in which the ground state redox potentials of the copper sites are offset by only 310 meV. We also demonstrate the ability of several of these complexes to effectively and unidirectionally shuttle energy between different metal centers, a property that could be of great use in the design of broadly absorbing and multifunctional multimetallic photocatalysts. This work provides an important step toward developing both a fundamental conceptual picture and a practical experimental handle with which synthetic chemists, spectroscopists, and theoreticians may collaborate to engineer cheap and efficient photocatalytic materials capable of performing coulombically demanding chemical transformations. PMID:29629153

  7. X-Ray Diffraction and the Discovery of the Structure of DNA

    Science.gov (United States)

    Crouse, David T.

    2007-01-01

    A method is described for teaching the analysis of X-ray diffraction of DNA through a series of steps utilizing the original methods used by James Watson, Francis Crick, Maurice Wilkins and Rosalind Franklin. The X-ray diffraction pattern led to the conclusion of the basic helical structure of DNA and its dimensions while basic chemical principles…

  8. Effects of proton irradiation on structure of NdFeB permanent magnets studied by X-ray diffraction and X-ray absorption fine structure

    International Nuclear Information System (INIS)

    Yang, L.; Zhen, L.; Xu, C.Y.; Sun, X.Y.; Shao, W.Z.

    2011-01-01

    The effects of proton irradiation on the structure of NdFeB permanent magnet were investigated by X-ray diffraction and X-ray absorption fine structure (XAFS). The results reveal that proton irradiation has no effect on the long-range structure, but significantly affects the atomic local structure of the NdFeB magnet. The alignment degree of the magnet decreases and the internal stress of the lattice increases after proton irradiation. XAFS results show that the coordination number of Fe-Nd in the first neighboring coordination shell of the Fe atoms decreases and the disorder degree increases.

  9. Effects of proton irradiation on structure of NdFeB permanent magnets studied by X-ray diffraction and X-ray absorption fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, L., E-mail: lzhen@hit.edu.c [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xu, C.Y.; Sun, X.Y.; Shao, W.Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2011-01-15

    The effects of proton irradiation on the structure of NdFeB permanent magnet were investigated by X-ray diffraction and X-ray absorption fine structure (XAFS). The results reveal that proton irradiation has no effect on the long-range structure, but significantly affects the atomic local structure of the NdFeB magnet. The alignment degree of the magnet decreases and the internal stress of the lattice increases after proton irradiation. XAFS results show that the coordination number of Fe-Nd in the first neighboring coordination shell of the Fe atoms decreases and the disorder degree increases.

  10. Structural study on Ni nanowires in an anodic alumina membrane by using in situ heating extended x-ray absorption fine structure and x-ray diffraction techniques

    International Nuclear Information System (INIS)

    Cai Quan; Chen Xing; Chen Zhongjun; Wang Wei; Mo Guang; Wu Zhonghua; Zhang Junxi; Zhang Lide; Pan Wei

    2008-01-01

    Polycrystalline Ni nanowires have been prepared by electrochemical deposition in an anodic alumina membrane template with a nanopore size of about 60 nm. In situ heating extended x-ray absorption fine structure and x-ray diffraction techniques are used to probe the atomic structures. The nanowires are identified as being mixtures of nanocrystallites and amorphous phase. The nanocrystallites have the same thermal expansion coefficient, of 1.7 x 10 -5 K -1 , as Ni bulk; however, the amorphous phase has a much larger thermal expansion coefficient of 3.5 x 10 -5 K -1 . Details of the Ni nanowire structures are discussed in this paper

  11. A structural study of ceramic oxides by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Akhtar, M.J.

    1995-01-01

    A detailed structural study of ceramic oxides is presented by employing X-ray Absorption Spectroscopy (XAS). In the present work X-ray Absorption Near Edge Structure (XANES) is used for the investigation of valence state of metal cations; whereas, Extended X-ray Absorption Fine Structure EXAFS) is employed for the determination for bond lengths, coordination numbers and nature of the elements present in the near neighbour shells surrounding the absorbing atom. These results show that local environment of dopant and host cations are different; and this variation in local structure depends on the nature and concentration of the dopant ions. (author)

  12. Hydrogen atoms in protein structures: high-resolution X-ray diffraction structure of the DFPase

    Science.gov (United States)

    2013-01-01

    Background Hydrogen atoms represent about half of the total number of atoms in proteins and are often involved in substrate recognition and catalysis. Unfortunately, X-ray protein crystallography at usual resolution fails to access directly their positioning, mainly because light atoms display weak contributions to diffraction. However, sub-Ångstrom diffraction data, careful modeling and a proper refinement strategy can allow the positioning of a significant part of hydrogen atoms. Results A comprehensive study on the X-ray structure of the diisopropyl-fluorophosphatase (DFPase) was performed, and the hydrogen atoms were modeled, including those of solvent molecules. This model was compared to the available neutron structure of DFPase, and differences in the protein and the active site solvation were noticed. Conclusions A further examination of the DFPase X-ray structure provides substantial evidence about the presence of an activated water molecule that may constitute an interesting piece of information as regard to the enzymatic hydrolysis mechanism. PMID:23915572

  13. Attosecond time-energy structure of X-ray free-electron laser pulses

    Science.gov (United States)

    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.

  14. Synthesis of nanoparticles through x-ray radiolysis using synchrotron radiation

    Science.gov (United States)

    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.

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    . At the air-water interface, the amphiphilic azobenzenes form noncrystalline but stable Langmuir films that display an unusual reversible monolayer collapse close to 35 mN/m. The structures and phase transitions were studied by X-ray reflectivity (XR) and grazing-incidence X-ray diffraction, both utilizing...... synchrotron radiation. Compression beyond the collapse point does not change the XR data, showing that the film is unchanged at the molecular level, even at areas less than half of that of the collapse. This leads to the conclusion that few macroscopic collapse sites are responsible for reversibly removing...

  16. Synthesis of the new boron hydride nido-undecaborane(15), B11H15, and the x-ray structure of its conjugate base tetradecahydroundecaborate(1-), [B11H14]-

    International Nuclear Information System (INIS)

    Getman, T.D.; Krause, J.A.; Shore, S.G.

    1988-01-01

    The preparation of nido-undecaborane, B 11 H 15 , from the protonation of K[B 11 H 14 ] and the subsequent deprotonation of B 11 H 15 by P(CH 3 ) 3 to give [P(CH 3 ) 3 H][B 11 H 14 ] is described. The structure of [P(CH 3 ) 3 H][B 11 H 14 ] has been determined from single-crystal x-ray data. The spectral data indicate that the boron framework of B 11 H 15 is similar to that of [B 11 H 14 ] - . 11 references, 1 figure

  17. Synthesis and X-ray Structural Studies of a Substituted 2,3,4,5-Tetrahydro-1H-3-benzazonine and a 1,2,3,5-Tetrahydro-4,3-benzoxazonine

    Directory of Open Access Journals (Sweden)

    Timothy S. Bailey

    2014-12-01

    Full Text Available Using a common 1-(1-phenylethenyl-1,2,3,4-tetrahydroisoquinoline precursor to the required ylide or N-oxide intermediate, the Stevens [2,3] and analogous Meisenheimer [2,3] sigmatropic rearrangements have been applied to afford concise syntheses of phenyl -substituted representatives of each of the reduced 1H-3-benzazonine and 4,3-benzoxazonine systems, respectively. Single crystal X-ray structure determinations were employed to define the conformational characteristics for each ring type.

  18. Synthesis, X-ray crystallography, and DFT calculations of a novel phosphoramide

    Czech Academy of Sciences Publication Activity Database

    Shariatinia, Z.; Dušek, Michal; Eigner, Václav

    2014-01-01

    Roč. 640, č. 14 (2014), 2945-2955 ISSN 0044-2313 R&D Projects: GA ČR(CZ) GA14-03276S Institutional support: RVO:68378271 Keywords : phosphoramide * x-ray structure * DFT Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.160, year: 2014

  19. The structure of the coronal soft X-ray source associated with the dark filament disappearance of 1991 September 28 using the Yohkoh Soft X-ray Telescope

    Science.gov (United States)

    Mcallister, Alan; Uchida, Yutaka; Tsuneta, Saku; Strong, Keith T.; Acton, Loren W.; Hiei, Eijiro; Bruner, Marilyn E.; Watanabe, Takashi; Shibata, Kazunari

    1992-01-01

    The structure of the coronal soft X-ray source associated with the dark filament disappearance on September 28, 1991, observed with the Soft X-ray Telescope, is examined as a possible example of the 'eruption-reconnection' model of filament disappearance. The results suggest, however, that this model may not fit. There is a strong possibility that much of the dark filament mass remains in the heated unwinding axial field.

  20. Photovoltaic X-ray detectors based on epitaxial GaAs structures

    Energy Technology Data Exchange (ETDEWEB)

    Achmadullin, R.A. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Artemov, V.V. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, 59 Leninski pr., Moscow B-333, 117333 (Russian Federation); Dvoryankin, V.F. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation)]. E-mail: vfd217@ire216.msk.su; Dvoryankina, G.G. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Dikaev, Yu.M. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Ermakov, M.G. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Ermakova, O.N. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Chmil, V.B. [Scientific State Center, High Energy Physics Institute, Protvino, Moscow region (Russian Federation); Holodenko, A.G. [Scientific State Center, High Energy Physics Institute, Protvino, Moscow region (Russian Federation); Kudryashov, A.A.; Krikunov, A.I.; Petrov, A.G.; Telegin, A.A. [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 1 Ac. Vvedenski square, Fryazino 141190, Moscow region (Russian Federation); Vorobiev, A.P. [Scientific State Center, High Energy Physics Institute, Protvino, Moscow region (Russian Federation)

    2005-12-01

    A new type of the photovoltaic X-ray detector based on epitaxial p{sup +}-n-n'-n{sup +} GaAs structures which provides a high efficiency of charge collection in the non-bias operation mode at room temperature is proposed. The GaAs epitaxial structures were grown by vapor-phase epitaxy on heavily doped n{sup +}-GaAs(1 0 0) substrates. The absorption efficiency of GaAs X-ray detector is discussed. I-V and C-V characteristics of the photovoltaic X-ray detectors are analyzed. The built-in electric field profiles in the depletion region of epitaxial structures are measured by the EBIC method. Charge collection efficiency to {alpha}-particles and {gamma}-radiation are measured. The application of X-ray detectors is discussed.

  1. Hard X-ray Microscopy with Elemental, Chemical and Structural Contrast

    International Nuclear Information System (INIS)

    Schroer, C.G.; Boye, P.; Feldkamp, J.P.

    2010-01-01

    We review hard X-ray microscopy techniques with a focus on scanning microscopy with synchrotron radiation. Its strength compared to other microscopies is the large penetration depth of hard x rays in matter that allows one to investigate the interior of an object without destructive sample preparation. In combination with tomography, local information from inside of a specimen can be obtained, even from inside special non-ambient sample environments. Different X-ray analytical techniques can be used to produce contrast, such as X-ray absorption, fluorescence, and diffraction, to yield chemical, elemental, and structural information about the sample, respectively. This makes X-ray microscopy attractive to many fields of science, ranging from physics and chemistry to materials, geo-, and environmental science, biomedicine, and nanotechnology. Our scanning microscope based on nanofocusing refractive X-ray lenses has a routine spatial resolution of about 100 nm and supports the contrast mechanisms mentioned above. In combination with coherent X-ray diffraction imaging, the spatial resolution can be improved to the 10 nm range. The current state-of-the-art of this technique is illustrated by several examples, and future prospects of the technique are given. (author)

  2. X-rays in protoplanetary disks : Their impact on the thermal and chemical structure, a grid of models

    NARCIS (Netherlands)

    Aresu, G.; Kamp, I.; Meijerink, R.; Woitke, P.; Thi, W. F.; Spaans, M.C.

    X-rays impact protoplanetary disks hydrostatic, thermal and chemical structure. The range of efficiency of X-rays is explored using a grid modelling approach: different parameters affects the structure of the disk, this determines different contribution of the X-ray radiation to the chemistry and

  3. Bone structure investigation using X-ray and neutron radiography techniques

    International Nuclear Information System (INIS)

    Kamali Moghaddam, K.; Taheri, T.; Ayubian, M.

    2008-01-01

    In this paper we report a study of the periodic variation of bone tissue humidity immediately after death using both neutron and X-ray radiography techniques. After death, bone tissue experiences sequential change over time. This change consists of organic and inorganic phase variations of the bone structure, as well as gradual reduction of the bone's water content. These variations are investigated by periodically imaging dead bone using X-ray and neutron radiography. Chemical separation techniques such as calcification and decalcification were used to separate the organic and inorganic phases of the bone. Comparison between X-ray and neutron radiographs of bone following phase separation can be potentially used to investigate the bone disease or to determine a cause of death. In our experiments, we use adult rat femur bones, and the interpretations of these results are presented based on our understanding of bone structure and images produced by neutron and X-ray photon interactions

  4. Bone structure investigation using X-ray and neutron radiography techniques

    Energy Technology Data Exchange (ETDEWEB)

    Kamali Moghaddam, K. [Nuclear Research Center (NRC), Atomic Energy Organization of Iran (AEOI), P.O. Box 11365-8486, Tehran (Iran, Islamic Republic of)], E-mail: kkamali@aeoi.org.ir; Taheri, T.; Ayubian, M. [Nuclear Research Center (NRC), Atomic Energy Organization of Iran (AEOI), P.O. Box 11365-8486, Tehran (Iran, Islamic Republic of)

    2008-01-15

    In this paper we report a study of the periodic variation of bone tissue humidity immediately after death using both neutron and X-ray radiography techniques. After death, bone tissue experiences sequential change over time. This change consists of organic and inorganic phase variations of the bone structure, as well as gradual reduction of the bone's water content. These variations are investigated by periodically imaging dead bone using X-ray and neutron radiography. Chemical separation techniques such as calcification and decalcification were used to separate the organic and inorganic phases of the bone. Comparison between X-ray and neutron radiographs of bone following phase separation can be potentially used to investigate the bone disease or to determine a cause of death. In our experiments, we use adult rat femur bones, and the interpretations of these results are presented based on our understanding of bone structure and images produced by neutron and X-ray photon interactions.

  5. Noninvasive 3D Structural Analysis of Arthropod by Synchrotron X-Ray Phase Contrast Tomography

    International Nuclear Information System (INIS)

    Yao, S.; Zong, Y.; Fan, J.; Sun, Z.; Jiang, H.

    2015-01-01

    X-ray imaging techniques significantly advanced our understanding of materials and biology, among which phase contrast X-ray microscopy has obvious advantages in imaging biological specimens which have low contrast by conventional absorption contrast microscopy. In this paper, three-dimensional microstructure of arthropod with high contrast has been demonstrated by synchrotron X-ray in-line phase contrast tomography. The external morphology and internal structures of an earthworm were analyzed based upon tomographic reconstructions with and without phase retrieval. We also identified and characterized various fine structural details such as the musculature system, the digestive system, the nervous system, and the circulatory system. This work exhibited the high efficiency, high precision, and wide potential applications of synchrotron X-ray phase contrast tomography in nondestructive investigation of low-density materials and biology.

  6. Titanium dioxide nanoparticles: synthesis, X-Ray line analysis and chemical composition study

    Energy Technology Data Exchange (ETDEWEB)

    Chenari, Hossein Mahmoudi, E-mail: mahmoudi_hossein@guilan.ac.ir, E-mail: h.mahmoudiph@gmail.com [University of Guilan, Rasht (Iran, Islamic Republic of); Seibel, Christoph; Hauschild, Dirk; Reinert, Friedrich [Karlsruhe Institute of Technology - KIT, Gemeinschaftslabor für Nanoanalytik, Karlsruhe (Germany); Abdollahian, Hossein [Nanotechnology Research Center of Urmia University, Urmia, (Iran, Islamic Republic of)

    2016-11-15

    TiO{sub 2} nanoparticles have been synthesized by the sol-gel method using titanium alkoxide and isopropanol as a precursor. The structural properties and chemical composition of the TiO{sub 2} nanoparticles were studied using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy.The X-ray powder diffraction pattern confirms that the particles are mainly composed of the anatase phase with the preferential orientation along [101] direction. The physical parameters such as strain, stress and energy density were investigated from the Williamson- Hall (W-H) plot assuming a uniform deformation model (UDM), and uniform deformation energy density model (UDEDM). The W-H analysis shows an anisotropic nature of the strain in nano powders. The scanning electron microscopy image shows clear TiO{sub 2} nanoparticles with particle sizes varying from 60 to 80nm. The results of mean particle size of TiO{sub 2} nanoparticles show an inter correlation with the W-H analysis and SEM results. Our X-ray photoelectron spectroscopy spectra show that nearly a complete amount of titanium has reacted to TiO{sub 2}. (author)

  7. Ultrafast Structural Dynamics in InSb Probed by Time-Resolved X-Ray Diffraction

    International Nuclear Information System (INIS)

    Chin, A.H.; Shank, C.V.; Chin, A.H.; Schoenlein, R.W.; Shank, C.V.; Glover, T.E.; Leemans, W.P.; Balling, P.

    1999-01-01

    Ultrafast structural dynamics in laser-perturbed InSb are studied using time-resolved x-ray diffraction with a novel femtosecond x-ray source. We report the first observation of a delay in the onset of lattice expansion, which we attribute to energy relaxation processes and lattice strain propagation. In addition, we observe direct indications of ultrafast disordering on a subpicosecond time scale. copyright 1999 The American Physical Society

  8. Structural investigation of GaInP nanowires using X-ray diffraction

    DEFF Research Database (Denmark)

    Kriegner, D.; Persson, Johan Mikael; Etzelstorfer, T.

    2013-01-01

    In this work the structure of ternary GaxIn1−xP nanowires is investigated with respect to the chemical composition and homogeneity. The nanowires were grown by metal–organic vapor-phase epitaxy. For the investigation of ensemble fluctuations on several lateral length scales, X-ray diffraction...... gradients along the sample by recording diffraction patterns at different positions. In addition, compositional variations were found also within single nanowires in X-ray energy dispersive spectroscopy measurements....

  9. The 16th International Conference on X-ray Absorption Fine Structure (XAFS16)

    Science.gov (United States)

    Grunwaldt, J.-D.; Hagelstein, M.; Rothe, J.

    2016-05-01

    This preface of the proceedings volume of the 16th International Conference on X- ray Absorption Fine Structure (XAFS16) gives a glance on the five days of cutting-edge X-ray science which were held in Karlsruhe, Germany, August 23 - 28, 2015. In addition, several satellite meetings took place in Hamburg, Berlin and Stuttgart, a Sino-German workshop, three data analysis tutorials as well as special symposia on industrial catalysis and XFELs were held at the conference venue.

  10. Microbeam high-resolution diffraction and x-ray standing wave methods applied to semiconductor structures

    International Nuclear Information System (INIS)

    Kazimirov, A; Bilderback, D H; Huang, R; Sirenko, A; Ougazzaden, A

    2004-01-01

    A new approach to conditioning x-ray microbeams for high angular resolution x-ray diffraction and scattering techniques is introduced. We combined focusing optics (one-bounce imaging capillary) and post-focusing collimating optics (miniature Si(004) channel-cut crystal) to generate an x-ray microbeam with a size of 10 μm and ultimate angular resolution of 14 μrad. The microbeam was used to analyse the strain in sub-micron thick InGaAsP epitaxial layers grown on an InP(100) substrate by the selective area growth technique in narrow openings between the oxide stripes. For the structures for which the diffraction peaks from the substrate and the film overlap, the x-ray standing wave technique was applied for precise measurements of the strain with a Δd/d resolution of better than 10 -4 . (rapid communication)

  11. Laser plasmas as x-ray sources for lithographic imaging of submicron structures

    International Nuclear Information System (INIS)

    Bijkerk, F.; van Dorssen, G.E.; van der Wiel, M.J.

    1988-01-01

    Laser radiation can be used efficiently to generate x-rays for lithographic imaging of submicron patterns, e.g., for VLSI device fabrication. Due to their short wavelength and high average power, excimer lasers show much potential for this application. Results are presented of scaling studies for high repetition rate excimer laser application, using the frequency doubled output of a low repetition rate Nd:YAG/Glass laser. Spectral and spatial characteristics of x-ray emission of the laser plasma are shown. The power density in the laser focus was 3 x 10 12 W/cm 2 . With this source Si x-ray masks with submicron Au absorber profiles are imaged into high sensitivity x-ray photoresist. For the exposures 80 laser shots sufficed to yield high quality submicron structures. Extrapolation of the results to a high power excimer laser reduces the exposure time of the photoresists to several seconds, enabling a wafer throughput at an industrial level

  12. X-ray laser diffraction for structure determination of the rhodopsin-arrestin complex

    Science.gov (United States)

    Zhou, X. Edward; Gao, Xiang; Barty, Anton; Kang, Yanyong; He, Yuanzheng; Liu, Wei; Ishchenko, Andrii; White, Thomas A.; Yefanov, Oleksandr; Han, Gye Won; Xu, Qingping; de Waal, Parker W.; Suino-Powell, Kelly M.; Boutet, Sébastien; Williams, Garth J.; Wang, Meitian; Li, Dianfan; Caffrey, Martin; Chapman, Henry N.; Spence, John C. H.; Fromme, Petra; Weierstall, Uwe; Stevens, Raymond C.; Cherezov, Vadim; Melcher, Karsten; Xu, H. Eric

    2016-04-01

    Serial femtosecond X-ray crystallography (SFX) using an X-ray free electron laser (XFEL) is a recent advancement in structural biology for solving crystal structures of challenging membrane proteins, including G-protein coupled receptors (GPCRs), which often only produce microcrystals. An XFEL delivers highly intense X-ray pulses of femtosecond duration short enough to enable the collection of single diffraction images before significant radiation damage to crystals sets in. Here we report the deposition of the XFEL data and provide further details on crystallization, XFEL data collection and analysis, structure determination, and the validation of the structural model. The rhodopsin-arrestin crystal structure solved with SFX represents the first near-atomic resolution structure of a GPCR-arrestin complex, provides structural insights into understanding of arrestin-mediated GPCR signaling, and demonstrates the great potential of this SFX-XFEL technology for accelerating crystal structure determination of challenging proteins and protein complexes.

  13. Local structure studies of Fe{sub 2}TeO{sub 6} using x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Harishchandra, E-mail: singh85harish@gmail.com [Homi Bhabha National Institute, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Yadav, A. K. [Atomic & Molecular Physics Division Bhabha Atomic Research Centre, Mumbai – 400 094 (India)

    2016-05-23

    In the present study, we have performed EXAFS measurements on powder samples of Fe{sub 2}TeO{sub 6} (FTO) to probe the local structure surrounding at the Fe site. The structural parameters (atomic coordination and lattice parameters) of FTO used for simulation of theoretical EXAFS spectra of the samples have been obtained from Rietveld refined structure on synchrotron X-ray Diffraction (SXRD) data. Quite similar and satisfactory structural parameters have been obtained from both the study, indicating goodness of synchrotron structural analysis over EXAFS analysis. SXRD and EXAFS results shows absence of any secondary phase proves current synthesis superior over reported techniques.

  14. Non-covalent interactions in 2-methylimidazolium copper(II) complex (MeImH)2[Cu(pfbz)4]: Synthesis, characterization, single crystal X-ray structure and packing analysis

    Science.gov (United States)

    Sharma, Raj Pal; Saini, Anju; Kumar, Santosh; Kumar, Jitendra; Sathishkumar, Ranganathan; Venugopalan, Paloth

    2017-01-01

    A new anionic copper(II) complex, (MeImH)2 [Cu(pfbz)4] (1) where, MeImH = 2-methylimidazolium and pfbz = pentafluorobenzoate has been isolated by reacting copper(II) sulfate pentahydrate, pentafluorobenzoic acid and 2-methylimidazole in ethanol: water mixture in 1:2:2 molar ratio. This complex 1 has been characterized by elemental analysis, thermogravimetric analysis, spectroscopic techniques (UV-Vis, FT-IR) and conductance measurements. The complex salt crystallizes in monoclinic crystal system with space group C2/c. Single crystal X-ray structure determination revealed the presence of discrete ions: [Cu(pfbz)4]2- anion and two 2-methylimidazolium cation (C4H7N2)+. The crystal lattice is stabilized by strong hydrogen bonding and F⋯F interactions between cationic-anionic and the anionic-anionic moieties respectively, besides π-π interactions.

  15. Study of gold nanoparticle synthesis by synchrotron x-ray diffraction and fluorescence

    Science.gov (United States)

    Yan, Zhongying; Wang, Xiao; Yu, Le; Moeendarbari, Sina; Hao, Yaowu; Cai, Zhonghou; Cheng, Xuemei

    Gold nanoparticles have a wide range of potential applications, including therapeutic agent delivery, catalysis, and electronics. Recently a new process of hollow nanoparticle synthesis was reported, the mechanism of which was hypothesized to involve electroless deposition around electrochemically evolved hydrogen bubbles. However, the growth mechanism still needs experimental evidence. We report investigation of this synthesis process using synchrotron x-ray diffraction and fluorescence measurements performed at beamline 2-ID-D of the Advanced Photon Source (APS). A series of gold nanoparticle samples with different synthesis time (50-1200 seconds) were deposited using a mixture electrolyte solution of Na3Au(SO3)2 and H4N2NiO6S2 on anodic aluminum oxide (AAO) membranes. The 2D mapping of fluorescence intensity and comparison of x-ray diffraction peaks of the samples have provided valuable information on the growth mechanism. Work at Bryn Mawr College and University of Texas at Arlington is supported by NSF Grants (1207085 and 1207377) and use of the APS at Argonne National Laboratory is supported by the U. S. Department of Energy under Contract No. DE-AC02-06CH11357.

  16. One pot synthesis, X-ray crystal structure of 2-(2‧-hydroxyphenyl)oxazolo[4,5-b]pyridine derivatives and studies of their optical properties

    Science.gov (United States)

    Briseño-Ortega, Horacio; Juárez-Guerra, Lizbeth; Rojas-Lima, Susana; Mendoza-Huizar, Luis Humberto; Vázquez-García, Rosa A.; Farfán, Norberto; Arcos-Ramos, Rafael; Santillan, Rosa; López-Ruiz, Heralio

    2018-04-01

    A series of five 2-(2-hydroxyphenyl)oxazolo [4,5-b]pyridines (HPOP) (3a-e), where four are novel, were synthesized by a mild, one pot, phenylboronic acid-NaCN catalyzed reaction. Spectroscopic characterization and photophysical properties of these compounds are reported. Absorption and excitation spectra of the compounds were dependent on the substituents in the phenyl ring. Fluorescence quantum yields (0.009-0.538) were associated with the donor strength and the position of the substituents. Also, DFT analysis allowed us to determine the contribution of diethylamino and methoxy moieties to the π-system, which is in agreement with the experimental data analyzed in solution and by cyclic voltammetry. The results obtained in the solid state by single-crystal X-ray diffraction experiments indicate that, the quasi-planarity envisioned for the explored compounds is present, supporting the hypothesis that both the H-bonding of a hydroxyl group to the Cdbnd N moiety and a donor groups such as diethylamino and methoxy moieties favor an electronic communication. Due to the facile synthesis and their photophysical properties, the novel HPOP 3a-e have potential application as organic semiconductors.

  17. Functional coordination polymers and MOFs from reactions of the lanthanides and barium with azole ligands. Synthesis and characterization with a focus on structure determination from X-ray powder diffraction data; Funktionale Koordinationspolymere und MOFs aus Reaktionen der Lanthanide und des Bariums mit Azol-Liganden. Synthese und Charakterisierung mit dem Fokus der Strukturbestimmung anhand von Roentgenpulverbeugungsdaten

    Energy Technology Data Exchange (ETDEWEB)

    Rybak, Jens-Christoph

    2012-07-01

    This thesis deals with the synthesis and characterization of coordination polymers and MOFs of the lanthanides and barium with different azolic N-heterocycles. A total of 18 new organic-inorganic hybrid materials, as well as a series of co-doped compounds is presented. Besides the structural characterization of these materials from X-ray diffraction powder data, the focus of the investigations is on the thermal and photoluminescence spectroscopic properties. The lanthanides La - Lu, except Eu and Pm, can be reacted with 1H-1,2,3-triazole to give the series of the isotypic dense 3D-MOFs {sup 3}{sub ∞}[Ln(Tz{sup *}){sub 3}]. Investigation of the photoluminescence properties of these compounds reveals a broad range of different luminescence phenomena, including the first observation of an intrinsic inner-filter effect of the Ln{sup 3+}-ions. The structure of this isotypic series of compounds was solved and refined from X-ray powder diffraction data. A 2D-polymorph of these compounds {sup 2}{sub ∞}[Ln(Tz{sup *}){sub 3}], is observed for Ln = Sm, Tb and was characterized by single crystal data. The reaction of Eu with 1H-benzotriazole yields the 1D-coordination polymer {sup 1}{sub ∞}[Eu(Btz){sub 2}(BtzH){sub 2}], which is the first example of a divalent rare earth benzotriazolate. Analysis of the thermal properties reveals the transformation to the 3D-MOF {sup 3}{sub ∞}[Eu(Btz){sub 2}] at higher temperatures. The structure of this material was also solved from X-ray powder diffraction data. Investigation of the photoluminescence properties of the co-doped compounds {sup 3}{sub ∞}[Ba{sub 1-x}Eu{sub x}(Im){sub 2}], which were obtained from reaction of the salt-like hydrides BaH{sub 2} and EuH{sub 2} with imidazole, show that the synthesis of luminescent MOF materials by co-doping of non-luminescent networks with luminescence centers is possible. The structure of these materials was solved from X-ray powder diffraction data of the undoped compound {sup 3}{sub

  18. X-ray absorption fine structure (XAFS) studies of cobalt silicide thin films

    International Nuclear Information System (INIS)

    Naftel, S.J.; Coulthard, I.; Hu, Y.; Sham, T.K.; Zinke-Allmang, M.

    1998-01-01

    Cobalt silicide thin films, prepared on Si(100) wafers, have been studied by X-ray absorption near edge structures (XANES) at the Si K-, L 2,3 - and Co K-edges utilizing both total electron (TEY) and fluorescence yield (FLY) detection as well as extended X-ray absorption fine structure (EXAFS) at the Co K-edge. Samples made using DC sputter deposition on clean Si surfaces and MBE were studied along with a bulk CoSi 2 sample. XANES and EXAFS provide information about the electronic structure and morphology of the films. It was found that the films studied have essentially the same structure as bulk CoSi 2 . Both the spectroscopy and materials characterization aspects of XAFS (X-ray absorption fine structures) are discussed

  19. Annealing induced atomic rearrangements on (Ga,In) (N,As) probed by hard X-ray photoelectron spectroscopy and X-ray absorption fine structure.

    Science.gov (United States)

    Ishikawa, Fumitaro; Higashi, Kotaro; Fuyuno, Satoshi; Morifuji, Masato; Kondow, Masahiko; Trampert, Achim

    2018-04-13

    We study the effects of annealing on (Ga 0.64 ,In 0.36 ) (N 0.045 ,As 0.955 ) using hard X-ray photoelectron spectroscopy and X-ray absorption fine structure measurements. We observed surface oxidation and termination of the N-As bond defects caused by the annealing process. Specifically, we observed a characteristic chemical shift towards lower binding energies in the photoelectron spectra related to In. This phenomenon appears to be caused by the atomic arrangement, which produces increased In-N bond configurations within the matrix, as indicated by the X-ray absorption fine structure measurements. The reduction in the binding energies of group-III In, which occurs concomitantly with the atomic rearrangements of the matrix, causes the differences in the electronic properties of the system before and after annealing.

  20. X-ray and photoelectron spectroscopy of the structure, reactivity, and electronic structure of semiconductor nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hamad, Kimberly Sue [Univ. of California, Berkeley, CA (United States)

    2000-01-01

    Semiconductor nanocrystals are a system which has been the focus of interest due to their size dependent properties and their possible use in technological applications. Many chemical and physical properties vary systematically with the size of the nanocrystal and thus their study enables the investigation of scaling laws. Due to the increasing surface to volume ratio as size is decreased, the surfaces of nanocrystals are expected to have a large influence on their electronic, thermodynamic, and chemical behavior. In spite of their importance, nanocrystal surfaces are still relatively uncharacterized in terms of their structure, electronic properties, bonding, and reactivity. Investigation of nanocrystal surfaces is currently limited by what techniques to use, and which methods are suitable for nanocrystals is still being determined. This work presents experiments using x-ray and electronic spectroscopies to explore the structure, reactivity, and electronic properties of semiconductor (CdSe, InAs) nanocrystals and how they vary with size. Specifically, x-ray absorption near edge spectroscopy (XANES) in conjunction with multiple scattering simulations affords information about the structural disorder present at the surface of the nanocrystal. X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectroscopy (UPS) probe the electronic structure in terms of hole screening, and also give information about band lineups when the nanocrystal is placed in electric contact with a substrate. XPS of the core levels of the nanocrystal as a function of photo-oxidation time yields kinetic data on the oxidation reaction occurring at the surface of the nanocrystal.

  1. Fabrication of high-aspect-ratio nano structures using a nano x-ray shadow mask

    International Nuclear Information System (INIS)

    Kim, Yong Chul; Lee, Seung S

    2008-01-01

    This paper describes a novel method for the fabrication of high-aspect-ratio nano structures (HAR-nano structures) using a nano x-ray shadow mask and deep x-ray lithography (DXRL). The nano x-ray shadow mask is fabricated by depositing an x-ray absorber layer (Au, 3 µm) onto the back side of a nano shadow mask. The nano shadow mask is produced with nano-sized apertures whose dimensions are reduced to several tens of nanometers by the accumulation of low-stress silicon nitride (Si x N y ) using the LPCVD process on the shadow mask. A shadow mask containing apertures with a size of 1 µm is fabricated on a bulk micromachined Si x N y membrane. The thickness of an absorber layer must be in the range of several tens of micrometers in order to obtain a contrast of more than 100 for the conventional DXRL process at the Pohang Light Source (PLS). However, a 3 µm thick absorber layer can provide a sufficient contrast if the modified DXRL of the central beam-stop method is used, which blocks high-energy x-rays. A nano shadow mask with 30 nm sized apertures is fabricated and a nano x-ray shadow mask with 250 nm sized apertures is fabricated by depositing a 3 µm thick absorber layer on a nano shadow mask with 500 nm sized apertures. HAR-nano structures (circles with a diameter of 420 nm and lines with a width of 274 nm) with aspect ratios of over 10:1 on a 3.2 µm SU-8 are successfully fabricated by using the nano x-ray shadow mask and the central beam-stop method

  2. Modeling Radiation Effects of Ultrasoft X Rays on the Basis of Amorphous Track Structure.

    Science.gov (United States)

    Buch, Tamara; Scifoni, Emanuele; Krämer, Michael; Durante, Marco; Scholz, Michael; Friedrich, Thomas

    2018-01-01

    There is experimental evidence that ultrasoft X rays (0.1-5 keV) show a higher biological effectiveness than high-energy photons. Similar to high-LET radiation, this is attributed to a rather localized dose distribution associated with a considerably smaller range of secondary electrons, which results in an increasing yield of double-strand breaks (DSBs) and potentially more complex lesions. We previously reported on the application of the Giant LOop Binary LEsion (GLOBLE) model to ultrasoft X rays, in which experimental values of the relative biological effectiveness (RBE) for DSB induction were used to show that this increasing DSB yield was sufficient to explain the enhanced effectiveness in the cell inactivation potential of ultrasoft X rays. Complementary to GLOBLE, we report here on a modeling approach to predict the increased DSB yield of ultrasoft X rays on the basis of amorphous track structure formed by secondary electrons, which was derived from Monte Carlo track structure simulations. This procedure is associated with increased production of single-strand break (SSB) clusters, which are caused by the highly localized energy deposition pattern induced by low-energy photons. From this, the RBE of ultrasoft X rays can be determined and compared to experimental data, showing that the inhomogeneity of the energy deposition pattern represents the key variable to describe the increased biological effectiveness of ultrasoft X rays. Thus, this work demonstrates an extended applicability of the amorphous track structure concept and tests its limits with respect to its predictive power. The employed model mechanism offers a possible explanation for how the cellular response to ultrasoft X rays is directly linked to the energy deposition properties on the nanometric scale.

  3. 3D visualization of subcellular structures of Schizosaccharomyces pombe by hard X-ray tomography.

    Science.gov (United States)

    Yang, Y; Li, W; Liu, G; Zhang, X; Chen, J; Wu, W; Guan, Y; Xiong, Y; Tian, Y; Wu, Z

    2010-10-01

    Cellular structures of the fission yeast, Schizosaccharomyces pombe, were examined by using hard X-ray tomography. Since cells are nearly transparent to hard X-rays, Zernike phase contrast and heavy metal staining were introduced to improve image contrast. Through using such methods, images taken at 8 keV displayed sufficient contrast for observing cellular structures. The cell wall, the intracellular organelles and the entire structural organization of the whole cells were visualized in three-dimensional at a resolution better than 100 nm. Comparison between phase contrast and absorption contrast was also made, indicating the obvious advantage of phase contrast for cellular imaging at this energy. Our results demonstrate that hard X-ray tomography with Zernike phase contrast is suitable for cellular imaging. Its unique abilities make it have potential to become a useful tool for revealing structural information from cells, especially thick eukaryotic cells. © 2010 The Authors Journal compilation © 2010 The Royal Microscopical Society.

  4. X-ray-to-current signal conversion characteristics of trench-structured photodiodes for direct-conversion-type silicon X-ray sensor

    International Nuclear Information System (INIS)

    Ariyoshi, Tetsuya; Funaki, Shota; Sakamoto, Kenji; Baba, Akiyoshi; Arima, Yutaka

    2017-01-01

    To reduce the radiation dose required in medical X-ray diagnoses, we propose a high-sensitivity direct-conversion-type silicon X-ray sensor that uses trench-structured photodiodes. This sensor is advantageous in terms of its long device lifetime, noise immunity, and low power consumption because of its low bias voltage. With this sensor, it is possible to detect X-rays with almost 100% efficiency; sensitivity can therefore be improved by approximately 10 times when compared with conventional indirect-conversion-type sensors. In this study, a test chip was fabricated using a single-poly single-metal 0.35 μm process. The formed trench photodiodes for the X-ray sensor were approximately 170 and 300 μm deep. At a bias voltage of 25 V, the absorbed X-ray-to-current signal conversion efficiencies were 89.3% (theoretical limit; 96.7%) at a trench depth of 170 μm and 91.1% (theoretical limit; 94.3%) at a trench depth of 300 μm. (author)

  5. Rapid X-ray crystal structure analysis in few second measurements using microstrip gas chamber

    CERN Document Server

    Ochi, A; Tanimori, T; Ohashi, Y; Toyokawa, H; Nishi, Y; Nishi, Y; Nagayoshi, T; Koishi, S

    2001-01-01

    X-ray crystal structure analysis using microstrip gas chamber was successfully carried out in a measurement time within a few seconds. The continuous rotation photograph method, in which most of the diffraction peaks can be obtained within one continuous rotation of the sample crystal (without stopping or oscillation), was applied for this measurement. As an example, the structure of a single crystal of ammonium bitartrate (r=1 mm, spherical) was measured. Diffraction spots from the sample, which were sufficient to obtain crystal structure, were successfully obtained by taking only 2 s measurements with a commercially available laboratory X-ray source.

  6. New structural studies of liquid crystal by reflectivity and resonant X-ray diffraction

    International Nuclear Information System (INIS)

    Fernandes, P.

    2007-04-01

    This memory presents three structural studies of smectic Liquid Crystals by reflectivity and resonant diffraction of X-rays. It is divided in five chapters. In the first a short introduction to Liquid Crystals is given. In particular, the smectic phases that are the object of this study are presented. The second chapter is consecrated to the X-ray experimental techniques that were used in this work. The three last chapters present the works on which this thesis can be divided. Chapter three demonstrates on free-standing films of MHPOBC (historic liquid crystal that possesses the antiferroelectric sub-phases) the possibility to extend the technique of resonant X-ray diffraction to liquid crystals without resonant element. In the fourth chapter the structure of the B 2 liquid crystal phase of bent-core molecules (or banana molecules) is elucidated by using resonant X-ray diffraction combined with polarization analysis of the diffracted beam. A model of the polarization of the resonant beam diffracted by four different structures proposed for the B 2 phase is developed in this chapter. In the fifth chapter a smectic binary mixture presenting a very original critical point of phase separation is studied by X-ray reflectivity and optical microscopy. A concentration gradient in the direction perpendicular to the plane of the film seems to be induced by the free-standing film geometry. The results of a simplified model of the system are compatible with this interpretation

  7. X-Ray structure and biophysical properties of rabbit fibroblast growth factor 1

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jihun; Blaber, Sachiko I.; Irsigler, Andre; Aspinwall, Eric; Blaber, Michael; (FSU)

    2010-01-14

    The rabbit is an important and de facto animal model in the study of ischemic disease and angiogenic therapy. Additionally, fibroblast growth factor 1 (FGF-1) is emerging as one of the most important growth factors for novel pro-angiogenic and pro-arteriogenic therapy. However, despite its significance, the fundamental biophysical properties of rabbit FGF-1, including its X-ray structure, have never been reported. Here, the cloning, crystallization, X-ray structure and determination of the biophysical properties of rabbit FGF-1 are described. The X-ray structure shows that the amino-acid differences between human and rabbit FGF-1 are solvent-exposed and therefore potentially immunogenic, while the biophysical studies identify differences in thermostability and receptor-binding affinity that distinguish rabbit FGF-1 from human FGF-1.

  8. Communication: The electronic structure of matter probed with a single femtosecond hard x-ray pulse

    Directory of Open Access Journals (Sweden)

    J. Szlachetko

    2014-03-01

    Full Text Available Physical, biological, and chemical transformations are initiated by changes in the electronic configuration of the species involved. These electronic changes occur on the timescales of attoseconds (10−18 s to femtoseconds (10−15 s and drive all subsequent electronic reorganization as the system moves to a new equilibrium or quasi-equilibrium state. The ability to detect the dynamics of these electronic changes is crucial for understanding the potential energy surfaces upon which chemical and biological reactions take place. Here, we report on the determination of the electronic structure of matter using a single self-seeded femtosecond x-ray pulse from the Linac Coherent Light Source hard x-ray free electron laser. By measuring the high energy resolution off-resonant spectrum (HEROS, we were able to obtain information about the electronic density of states with a single femtosecond x-ray pulse. We show that the unoccupied electronic states of the scattering atom may be determined on a shot-to-shot basis and that the measured spectral shape is independent of the large intensity fluctuations of the incoming x-ray beam. Moreover, we demonstrate the chemical sensitivity and single-shot capability and limitations of HEROS, which enables the technique to track the electronic structural dynamics in matter on femtosecond time scales, making it an ideal probe technique for time-resolved X-ray experiments.

  9. THE CONTRIBUTION OF X-RAY BINARIES TO THE EVOLUTION OF LATE-TYPE GALAXIES: EVOLUTIONARY POPULATION SYNTHESIS SIMULATIONS

    International Nuclear Information System (INIS)

    Zuo Zhaoyu; Li Xiangdong

    2011-01-01

    X-ray studies of normal late-type galaxies have shown that non-nuclear X-ray emission is typically dominated by X-ray binaries and provides a useful measure of star formation activity. We have modeled the X-ray evolution of late-type galaxies over the ∼14 Gyr of cosmic history, with an evolutionary population synthesis code developed by Hurley et al. Our calculations reveal a decrease in the X-ray luminosity-to-mass ratio L X /M with time, in agreement with observations. We show that this decrease is a natural consequence of stellar and binary evolution and the mass accumulating process in galaxies. The X-ray-to-optical luminosity ratio L X /L B is found to be fairly constant (around ∼10 30 erg s -1 L -1 B,sun ) and insensitive to the star formation history in the galaxies. The nearly constant value of L X /L B is in conflict with the observed increase in L X /L B from z = 0 to 1.4. The discrepancy may be caused by intense obscured star formation activity that leads to a nonlinear relationship between X-ray and B-band emission.

  10. Synthesis, characterization, X-ray crystal structure and conductometry studying of a number of new Schiff base complexes; a new example of binuclear square pyramidal geometry of Cu(II) complex bridged with an oxo group

    Science.gov (United States)

    Golbedaghi, Reza; Alavipour, Ehsan

    2015-11-01

    Three new binuclear Cu(II), Mn(II), Co(II) complexes [Cu2(L) (ClO4)](ClO4)2 (1), [Mn2(L) (ClO4)](ClO4)2 (2), and [Co2(L) (ClO4)](ClO4)2 (3), {L = 1,3-bis(2-((Z)-(2-aminopropylimino)methyl)phenoxy)propan-2-ol} have been synthesized. Single crystal X-ray structure analysis of complex 1 showed that the complex is binuclear and all nitrogen and oxygen atoms of ligand (N4O3) are coordinated to two Cu(II) center ions. In addition, the crystal structure studying shows, a perchlorate ion has been bridged to the Cu(II) metal centers. However, two distorted square pyramidal Cu(II) ions are bridged asymmetrically by a perchlorate ion and oxygen of hydroxyl group of Schiff base ligand. In addition, the conductometry behaviors of all complexes were studied in acetonitrile solution.

  11. Photovoltaic x-ray detectors based on the GaAs epitaxial structures

    CERN Document Server

    Akhmadullin, R A; Dvoryankina, G G; Dikaev, Y M; Ermakov, M G; Ermakova, O N; Krikunov, A I; Kudryashov, A A; Petrov, A G; Telegin, A A

    2002-01-01

    The new photovoltaic detector of the X-ray radiation is proposed on the basis of the GaAs epitaxial structures, which operates with high efficiency of the charge carriers collection without shift voltage and at the room temperature. The structures are grown by the method of the gas-phase epitaxy on the n sup + -type highly-alloyed substrates. The range of sensitivity to the X-ray radiation is within the range of effective energies from 8 up to 120 keV. The detector maximum response in the current short circuit mode is determined

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

    International Nuclear Information System (INIS)

    Antonio, M.R.; Soderholm, L.

    1995-01-01

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

  13. Method of evaluation of structural (screen) and quantum graininess of X-ray pictures

    Energy Technology Data Exchange (ETDEWEB)

    Gurvich, A M; Shamanov, A A; Erofeeva, N D [Nauchno-Issledovatel' skij Inst. Rentgenologii i Radiologii, Moscow (USSR)

    1979-03-01

    Proposed is a method for quantitative determination of graininess of X-ray pictures (gamma-ray images), the graininess being conditioned by the structure of amplifying screens and quantum fluctuations. The method is based on the determination of threshold brightness at which the picture graininess becomes obvious. It is shown that at low effective quantum energy (Esub(eff.) <= 50 keV) the graininess observed is for the most part structural (screen). Its growth is connected with quantum fluctuations when increasing Esub(eff.) up to 150 keV and using screens with high output values of X-ray luminescence and the coefficient of spectral accordance to the film.

  14. X-ray absorption in GaGdN: A study of local structure

    Science.gov (United States)

    Martínez-Criado, G.; Sancho-Juan, O.; Garro, N.; Sans, J. A.; Cantarero, A.; Susini, J.; Roever, M.; Mai, D.-D.; Bedoya-Pinto, A.; Malindretos, J.; Rizzi, A.

    2008-07-01

    In this study, we report on the incorporation of dilute Gd amounts into GaN films grown by molecular beam epitaxy. A combination of x-ray fluorescence with x-ray absorption spectroscopic techniques enabled us to examine not only the distribution of rare earth atoms in the GaN matrix but also the short-range structural order. Our results show Gd atoms in a trivalent state with tetrahedral coordination, thus substituting Ga in the wurtzite GaN structure.

  15. X-ray absorption in GaGdN: A study of local structure

    International Nuclear Information System (INIS)

    Martinez-Criado, G.; Sans, J. A.; Susini, J.; Sancho-Juan, O.; Cantarero, A.; Garro, N.; Roever, M.; Mai, D.-D.; Bedoya-Pinto, A.; Malindretos, J.; Rizzi, A.

    2008-01-01

    In this study, we report on the incorporation of dilute Gd amounts into GaN films grown by molecular beam epitaxy. A combination of x-ray fluorescence with x-ray absorption spectroscopic techniques enabled us to examine not only the distribution of rare earth atoms in the GaN matrix but also the short-range structural order. Our results show Gd atoms in a trivalent state with tetrahedral coordination, thus substituting Ga in the wurtzite GaN structure

  16. Structural mechanics of the solar-A Soft X-ray Telescope

    Science.gov (United States)

    Jurcevich, B. K.; Bruner, M. E.; Gowen, K. F.

    1992-01-01

    The Soft X-ray Telescope (SXT) is one of four major instruments that constitute the payload of the NASA-Japanese mission YOHKOH (formerly known as Solar-A), scheduled to be launched in August, 1991. This paper describes the design of the SXT, the key system requirements, and the SXT optical and structural systems. Particular attention is given to the design considerations for stiffness and dimensional stability, temperature compensation, and moisture sensitivyty control. Consideration is also given to the X-ray mirror, the aspect telescope, the entrance filters, the mechanical structure design, the aft support plate and mount, the SXT finite element model, and other subsystems.

  17. Purification, crystallization and preliminary X-ray structure analysis of the laccase from Ganoderma lucidum

    International Nuclear Information System (INIS)

    Lyashenko, Andrey V.; Belova, Oksana; Gabdulkhakov, Azat G.; Lashkov, Alexander A.; Lisov, Alexandr V.; Leontievsky, Alexey A.; Mikhailov, Al’bert M.

    2011-01-01

    The purification, crystallization and preliminary X-ray structure analysis of the laccase from G. lucidum are reported. The ligninolytic enzymes of the basidiomycetes play a key role in the global carbon cycle. A characteristic property of these enzymes is their broad substrate specificity, which has led to their use in various biotechnologies, thus stimulating research into the three-dimensional structures of ligninolytic enzymes. This paper presents the purification, crystallization and preliminary X-ray analysis of the laccase from the ligninolytic basidiomycete Ganoderma lucidum

  18. X-ray diffraction study of the structure of detonation nanodiamonds

    International Nuclear Information System (INIS)

    Ozerin, A. N.; Kurkin, T. S.; Ozerina, L. A.; Dolmatov, V. Yu.

    2008-01-01

    The spatial structure of aggregates formed by detonation nanodiamonds is investigated using the wide-angle and small-angle X-ray scattering techniques. The effective sizes of crystallites and the crystallite size distribution function are determined. The shape of scattering aggregates is restored from the small-angle X-ray scattering data. An analysis of the results obtained allowed the conclusion that the nanodiamond aggregates have an extended spatial structure composed of nine to ten clusters, each involving four to five crystallites with a crystal lattice of the diamond type

  19. Reflections on hard X-ray photon-in/photon-out spectroscopy for electronic structure studies

    Energy Technology Data Exchange (ETDEWEB)

    Glatzel, Pieter, E-mail: glatzel@esrf.fr [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Weng, Tsu-Chien; Kvashnina, Kristina; Swarbrick, Janine; Sikora, Marcin [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Gallo, Erik [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Department of Inorganic, Physical and Materials Chemistry, INSTM Reference Center and NIS Centre of Excellence, Università di Torino, Via P. Giuria 7, I-10125 Torino (Italy); Smolentsev, Nikolay [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Research Center for Nanoscale Structure of Matter, Southern Federal University, str. Zorge 5, 344090 Rostov-on-Don (Russian Federation); Mori, Roberto Alonso [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France)

    2013-06-15

    Highlights: ► Overview of some recent developments in hard X-ray RXES/RIXS. ► Evaluation of spectral line broadening in RXES/RIXS. ► Modelling of RXES/RIXS by ground state DFT calculations. ► Discussion on when HERFD provides a good approximation to XAS. -- Abstract: An increasing community of researchers in various fields of natural sciences is combining X-ray absorption with X-ray emission spectroscopy (XAS–XES) to study electronic structure. With the applications becoming more diverse, the objectives and the requirements in photon-in/photon-out spectroscopy are becoming broader. It is desirable to find simple experimental protocols, robust data reduction and theoretical tools that help the experimentalist to understand their data and learn about the electronic structure. This article presents a collection of considerations on non-resonant and resonant XES with the aim to guide the experimentalist to make good use of this technique.

  20. Investigation of nanoscale structures by small-angle X-ray scattering in a radiochromic dosimeter

    DEFF Research Database (Denmark)

    Skyt, Peter Sandegaard; Jensen, Grethe Vestergaard; Wahlstedt, Isak Hannes

    2014-01-01

    This study examines the nanoscale structures in a radiochromic dosimeter that was based on leuco-malachite-green dye and the surfactant sodium dodecyl sulfate (SDS) suspended in a gelatin matrix. Small-angle X-ray scattering was used to investigate the structures of a range of compositions...

  1. X-ray structure amplitudes for GaAs and InP

    International Nuclear Information System (INIS)

    Pietsch, U.

    1985-01-01

    The structure amplitudes of GaAs and InP are calculated taking into account the nonspherical parts of the valence electron density by means of a static bond charge model. The best known temperature factors and dispersion coefficients are employed. The calculated structure amplitudes should help determining exactly the shape of X-ray diffraction patterns. (author)

  2. Composite structure of helicopter rotor blades studied by neutron- and X-ray radiography

    International Nuclear Information System (INIS)

    Balasko, M.; Veres, I.; Molnar, Gy.; Balasko, Zs.; Svab, E.

    2004-01-01

    In order to inspect the possible defects in the composite structure of helicopter rotor blades combined neutron- and X-ray radiography investigations were performed at the Budapest Research Reactor. Imperfections in the honeycomb structure, resin rich or starved areas at the core-honeycomb surfaces, inhomogeneities at the adhesive filling and water percolation at the sealing interfaces of the honeycomb sections were discovered

  3. Composite structure of helicopter rotor blades studied by neutron- and X-ray radiography

    Science.gov (United States)

    Balaskó, M.; Veres, I.; Molnár, Gy.; Balaskó, Zs.; Sváb, E.

    2004-07-01

    In order to inspect the possible defects in the composite structure of helicopter rotor blades combined neutron- and X-ray radiography investigations were performed at the Budapest Research Reactor. Imperfections in the honeycomb structure, resin rich or starved areas at the core-honeycomb surfaces, inhomogeneities at the adhesive filling and water percolation at the sealing interfaces of the honeycomb sections were discovered.

  4. X-ray propagation through a quasi-ordered multilayered structure ...

    African Journals Online (AJOL)

    We investigate the propagation of short wavelength transverse electric x-rays through a quasiordered (Fibonacci) atomically commensurate multilayered structure using a transfer matrix model which treats each atomic plane as a diffraction unit. The reflectance spectrum has a rich structure being dominated by peaks ...

  5. X-ray detectors for structure investigations constructed at JINR

    Energy Technology Data Exchange (ETDEWEB)

    Chernenko, S P [LHE Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Cheremukhina, G A [LHE Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Fateev, O V [LHE Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Smykov, L P [LHE Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Vasiliev, S E [LHE Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Zanevsky, Yu V [LHE Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Kheiker, D M [Institute of Crystallography, Leninsky prosp. 59, 117333 Moscow (Russian Federation); Popov, A N [Institute of Crystallography, Leninsky prosp. 59, 117333 Moscow (Russian Federation)

    1994-09-01

    The performance characteristics of a few high resolution position-sensitive detectors constructed at JINR are presented. The detectors supplied with original software operate with an IBM PC/AT. One of these devices has been succesfully applied for protein molecule structure investigations and the other for studies of the structure-forming process during combustion. The preliminary parameters of the high count rate MWPC with parallel electronics and the testing results of the microstrip detector are given. ((orig.))

  6. A structural study of bone changes in knee osteoarthritis by synchrotron-based X-ray fluorescence and X-ray absorption spectroscopy techniques

    Science.gov (United States)

    Sindhupakorn, Bura; Thienpratharn, Suwittaya; Kidkhunthod, Pinit

    2017-10-01

    Osteoarthritis (OA) is characterized by degeneration of articular cartilage and thickening of subchondral bone. The present study investigated the changing of biochemical components of cartilage and bone compared between normal and OA people. Using Synchrotron-based X-ray fluorescence (SR-XRF) and X-ray absorption spectroscopy (XAS) techniquesincluding X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) were employed for the bone changes in kneeosteoarthritisstudies. The bone samples were collected from various osteoarthritis patients with both male and female in the ages range between 20 and 74 years old. SR-XRF results excited at 4240 eV for Ca elements show a majority three main groups, based on their XRF intensities, 20-36 years, 40-60 years and over 70 years, respectively. By employing XAS techniques, XANES features can be used to clearly explain in term of electronic transitions occurring in bone samples which are affected from osteoarthritis symptoms. Moreover, a structural change around Ca ions in bone samples is obviously obtained by EXAFS results indicating an increase of Ca-amorphous phase when the ages increase.

  7. Target surface structure effects on x-ray generation from laser produced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Nishikawa, Tadashi; Nakano, Hidetoshi; Uesugi, Naoshi [NTT Basic Research Laboratories, Atsugi, Kanagawa (Japan)

    2000-03-01

    We demonstrated two different methods to increase the x-ray conversion efficiency of laser-produced plasma by modifying the target surface structure. One way is making a rectangular groove on a target surface and confining a laser-produced plasma in it. By the plasma collision process, a time and wavelength (4-10 nm) integrated soft x-ray fluence enhancement of 35 times was obtained at a groove width of 20 {mu}m and a groove depth of 100 {mu}m on a Nd-doped glass target. The other way is making an array of nanoholes on an alumina target and increasing the laser interaction depth with it. The x-ray fluence enhancement increases as the ionization level of Al becomes higher and the x-ray wavelength becomes shorter. Over 50-fold enhancement was obtained at a soft x-ray wavelength around 6 nm, which corresponds to the emission from Al{sup 8+,9+} ions. (author)

  8. Target surface structure effects on x-ray generation from laser produced plasma

    International Nuclear Information System (INIS)

    Nishikawa, Tadashi; Nakano, Hidetoshi; Uesugi, Naoshi

    2000-01-01

    We demonstrated two different methods to increase the x-ray conversion efficiency of laser-produced plasma by modifying the target surface structure. One way is making a rectangular groove on a target surface and confining a laser-produced plasma in it. By the plasma collision process, a time and wavelength (4-10 nm) integrated soft x-ray fluence enhancement of 35 times was obtained at a groove width of 20 μm and a groove depth of 100 μm on a Nd-doped glass target. The other way is making an array of nanoholes on an alumina target and increasing the laser interaction depth with it. The x-ray fluence enhancement increases as the ionization level of Al becomes higher and the x-ray wavelength becomes shorter. Over 50-fold enhancement was obtained at a soft x-ray wavelength around 6 nm, which corresponds to the emission from Al 8+,9+ ions. (author)

  9. Synthesis and X-ray Powder Structure of a New Pillared Layered Cadmium Phosphonate, Giving Evidence that the Intercalation of Alkylamines into Cd(O(3)PR).H(2)O Is Topotactic.

    Science.gov (United States)

    Fredoueil, Florence; Massiot, Dominique; Janvier, Pascal; Gingl, Franz; Bujoli-Doeuff, Martine; Evain, Michel; Clearfield, Abraham; Bujoli, Bruno

    1999-04-19

    A new pillared layered phosphonate, cadmium 2-aminoethylphosphonate, Cd(O(3)PC(2)H(4)NH(2)) (1), has been synthesized, and its structure was solved ab initio from X-ray powder diffraction data and refined by Rietveld methods. Compound 1 is orthorhombic: space group Pna2(1), a = 15.4643(2) Å, b = 5.16512(7) Å, c = 6.27650(8) Å, and Z = 4. Its layer arrangement is similar to that in Cd(O(3)PR).H(2)O, except that the water molecule coordinated to cadmium in Cd(O(3)PR).H(2)O is replaced by the nitrogen atom from the amino ends of the ethyl chains borne by phosphorus of the upper and lower layers. The strong similarity of the IR, (31)P, and (113)Cd NMR data for Cd(O(3)PC(2)H(4)NH(2)) and Cd(O(3)PCH(3)).n-NH(2)C(4)H(9) clearly shows the topotactic character of the intercalation of n-alkylamines in the dehydrated form of Cd(O(3)PR).H(2)O to yield Cd(O(3)PR).n-NH(2)R'.

  10. N-(4-Nitrobenzoyl)-N'-(1,5-dimethyl-3-oxo-2-phenyl-1H-3(2H)-pyrazolyl)-thiourea hydrate: Synthesis, spectroscopic characterization, X-ray structure and DFT studies

    Science.gov (United States)

    Arslan, N. Burcu; Kazak, Canan; Aydın, Fatma

    2012-04-01

    The title molecule (C19H17N5O4S·H2O) was synthesized and characterized by IR-NMR spectroscopy, MS and single-crystal X-ray diffraction. The molecular geometry, vibrational frequencies and gauge-independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the compound in the ground state have been calculated by using the density functional theory (DFT) method with 6-31G(d) basis set, and compared with the experimental data. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. The calculated results show that the optimized geometries can well reproduce the crystal structural parameters, and the theoretical vibrational frequencies and 1H and 13C NMR chemical shift values show good agreement with experimental data. To determine conformational flexibility, the molecular energy profile of the title compound was obtained with respect to the selected torsion angle, which was varied from -180° to +180° in steps of 10°. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis and thermodynamic properties of the compound were investigated by theoretical calculations.

  11. Stereoselective synthesis of ( E)-4-(imidazo[1,2- a]pyrid-2-yl)-3-(4-methylphenylsulfonyl)but-3-en-2-one. X-ray crystal structure and conformational analysis

    Science.gov (United States)

    Roche, D.; Force, L.; Carpy, A.; Gardette, D.; Madesclaire, M.

    1998-06-01

    The title compound, gem-ketovinylsulfone 3, was obtained stereoselectively (de > 98%) by the action of the α-anion from p-tolylsulfonylacetone 1 on imidazol[1,2- a]pyridine-2-carbaldehyde 2 in chelation-controlled conditions in the presence of a Lewis acid (ZnCl 2). The X-ray crystal structure of 3 [C 18H 16N 2O 3S: Mt = 340.4, orthorhombic, Pbca, a = 12.208(3) Å, b = 18.848(4) Å, c = 14.566(11) Å, V = 3.351(3) Å3, Z = 8, Dcalc = 1.349 g cm -3, λ( CuKα) = 1.54178 Å, μ = 1.83 mm -1, F(000) = 1424, T = 293 K, R = 0.061 for 2.046 observed reflections] was determined, and confirmed the ( E) configuration. Despite the conjugate position of the vinyl double bond, quasi-coplanar with the imidazopyridine heterocycle, there is no evidence of p-electron delocalization. The crystal cohesion is ensured by a dense network of van der Waals contacts. The conformational analysis of the ( E) and ( Z) stereoisomers was performed by molecular dynamics simulation, and showed the ( E) isomer to be 9.1 kJ mol -1 more stable than the ( Z) isomer.

  12. Large-area soft x-ray projection lithography using multilayer mirrors structured by RIE

    Science.gov (United States)

    Rahn, Steffen; Kloidt, Andreas; Kleineberg, Ulf; Schmiedeskamp, Bernt; Kadel, Klaus; Schomburg, Werner K.; Hormes, F. J.; Heinzmann, Ulrich

    1993-01-01

    SXPL (soft X-ray projection lithography) is one of the most promising applications of X-ray reflecting optics using multilayer mirrors. Within our collaboration, such multilayer mirrors were fabricated, characterized, laterally structured and then used as reflection masks in a projecting lithography procedure. Mo/Si-multilayer mirrors were produced by electron beam evaporation in UHV under thermal treatment with an in-situ X-ray controlled thickness in the region of 2d equals 14 nm. The reflectivities measured at normal incidence reached up to 54%. Various surface analysis techniques have been applied in order to characterize and optimize the X-ray mirrors. The multilayers were patterned by reactive ion etching (RIE) with CF(subscript 4), using a photoresist as the etch mask, thus producing X-ray reflection masks. The masks were tested in the synchrotron radiation laboratory of the electron accelerator ELSA at the Physikalisches Institut of Bonn University. A double crystal X-ray monochromator was modified so as to allow about 0.5 cm(superscript 2) of the reflection mask to be illuminated by white synchrotron radiation. The reflected patterns were projected (with an energy of 100 eV) onto the resist (Hoechst AZ PF 514), which was mounted at an average distance of about 7 mm. In the first test-experiments, structure sizes down to 8 micrometers were nicely reproduced over the whole of the exposed area. Smaller structures were distorted by Fresnel-diffraction. The theoretically calculated diffraction images agree very well with the observed images.

  13. Ab initio structure determination via powder X-ray diffraction

    Indian Academy of Sciences (India)

    Unknown

    Although the method of structure completion when once the starting model is provided is ... In this article a survey of the recent development in this area is ..... The Monte Carlo method 4,9 differs from the traditional approaches as it operates in.

  14. Forming a structure of the CoNiFe alloys by X-ray irradiation

    Science.gov (United States)

    Valko, Natalia; Kasperovich, Andrey; Koltunowicz, Tomasz N.

    The experimental data of electrodeposition kinetics researches and structure formation of ternary CoNiFe alloys deposited onto low-carbon steel 08kp in the presence of X-rays are presented. Relations of deposit rate, current efficiencies, element and phase compositions of CoNiFe coatings formed from sulfate baths with respect to cathode current densities (0.5-3A/dm2), electrolyte composition and irradiation were obtained. It is shown that, the CoNiFe coatings deposited by the electrochemical method involving exposure of the X-rays are characterized by more perfect morphology surfaces with less developed surface geometry than reference coatings. The effect of the X-ray irradiation on the electrodeposition of CoNiFe coatings promotes formatting of alloys with increased electropositive component and modified phase composition.

  15. Structure investigation of metal ions clustering in dehydrated gel using x-ray anomalous dispersion effect

    CERN Document Server

    Soejima, Y; Sugiyama, M; Annaka, M; Nakamura, A; Hiramatsu, N; Hara, K

    2003-01-01

    The structure of copper ion clusters in dehydrated N-isopropylacrylamide/sodium acrylate (NIPA/SA) gel has been studied by means of small angle X-ray scattering (SAXS) method. In order to distinguish the intensity scattered by Cu ions, the X-ray anomalous dispersion effect around the Cu K absorption edge has been coupled with SAXS. It is found that the dispersion effect dependent on the incident X-ray energy is remarkable only at the momentum transfer q = 0.031 A sup - sup 1 , where a SAXS peak is observed. The results indicate that copper ions form clusters in the dehydrated gel, and that the mean size of clusters is the same as that of SA clusters produced by microphase separation. It is therefore naturally presumed that copper ions are adsorbed into the SA molecules. On the basis of the presumption, a mechanism is proposed for microphase-separation and clustering of Cu ions.

  16. Two-dimensional imaging detectors for structural biology with X-ray lasers.

    Science.gov (United States)

    Denes, Peter

    2014-07-17

    Our ability to harness the advances in microelectronics over the past decade(s) for X-ray detection has resulted in significant improvements in the state of the art. Biology with X-ray free-electron lasers present daunting detector challenges: all of the photons arrive at the same time, and individual high peak power pulses must be read out shot-by-shot. Direct X-ray detection in silicon pixel detectors--monolithic or hybrid--are the standard for XFELs today. For structural biology, improvements are needed for today's 10-100 Hz XFELs, and further improvements are required for tomorrow's 10+ kHz XFELs. This article will discuss detector challenges, why they arise and ways to overcome them, along with the current state of the art. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  17. Single crystal X-ray structure of the artists’ pigment zinc yellow

    DEFF Research Database (Denmark)

    Simonsen, Kim Pilkjær; Christiansen, Marie Bitsch; Vinum, Morten Gotthold

    2017-01-01

    electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and powder X-ray diffraction (PXRD), showed that the synthesised products and the industrial pigment were identical. Single-crystal X-ray crystallography......The artists’ pigment zinc yellow is in general described as a complex potassium zinc chromate with the empirical formula 4ZnCrO4·K2O·3H2O. Even though the pigment has been in use since the second half of the 19th century also in large-scale industrial applications, the exact structure had hitherto...... been unknown. In this work, zinc yellow was synthesised by precipitation from an aqueous solution of zinc nitrate and potassium chromate under both neutral and basic conditions, and the products were compared with the pigment used in industrial paints. Analyses by Raman microscopy (MRS), scanning...

  18. Rapid characterization of a nanomaterial structure using X-ray reciprocal-lattice-space imaging

    International Nuclear Information System (INIS)

    Sakata, Osami; Yoshimoto, Mamoru; Miki, Kazushi

    2006-01-01

    The X-ray reciprocal-lattice-space imaging method is able to record the reciprocal-lattice-space of nanostructure by sample-and-detector fixed geometry. This method was developed by the surface structure analysis beam line BL13XU of SPring-8. Outline of the X-ray diffraction method and basic principles of the X-ray reciprocal-lattice-space imaging method, and application examples are stated. The method is able to find out the Bragg conditions of nanostructure of surface in the atmosphere. The reciprocal-lattice of the embedded trace atomic wires was observed. The trace atoms of Bi atomic wires embedded in silicone showed the diffraction signal and image by a short exposure time. This method is useful at rapid non-destructive measurement of nanostructure. (S.Y.)

  19. Parameter study of self-absorption effects in Total Reflection X-ray Fluorescence-X-ray Absorption Near Edge Structure analysis of arsenic

    International Nuclear Information System (INIS)

    Meirer, F.; Pepponi, G.; Streli, C.; Wobrauschek, P.; Kregsamer, P.; Zoeger, N.; Falkenberg, G.

    2008-01-01

    Total reflection X-ray Fluorescence (TXRF) analysis in combination with X-ray Absorption Near Edge Structure (XANES) analysis is a powerful method to perform chemical speciation studies at trace element levels. However, when measuring samples with higher concentrations and in particular standards, damping of the oscillations is observed. In this study the influence of self-absorption effects on TXRF-XANES measurements was investigated by comparing measurements with theoretical calculations. As(V) standard solutions were prepared at various concentrations and dried on flat substrates. The measurements showed a correlation between the damping of the oscillations and the As mass deposited. A Monte-Carlo simulation was developed using data of the samples shapes obtained from confocal white light microscopy. The results showed good agreement with the measurements; they confirmed that the key parameters are the density of the investigated atom in the dried residues and the shape of the residue, parameters that combined define the total mass crossed by a certain portion of the incident beam. The study presents a simple approach for an a priori evaluation of the self-absorption in TXRF X-ray absorption studies. The consequences for Extended X-ray Absorption Fine Structure (EXAFS) and XANES measurements under grazing incidence conditions are discussed, leading to the conclusion that the damping of the oscillations seems to make EXAFS of concentrated samples non feasible. For XANES 'fingerprint' analysis samples should be prepared with a deposited mass and sample shape leading to an acceptable absorption for the actual investigation

  20. Surface extended x-ray absorption fine structure of low-Z absorbates using fluorescence detection

    International Nuclear Information System (INIS)

    Stoehr, J.; Kollin, E.B.; Fischer, D.A.; Hastings, J.B.; Zaera, F.; Sette, F.

    1985-05-01

    Comparison of x-ray fluorescence yield (FY) and electron yield surface extended x-ray absorption fine structure spectra above the S K-edge for c(2 x 2) S on Ni(100) reveals an order of magnitude higher sensitivity of the FY technique. Using FY detection, thiophene (C 4 H 4 S) chemisorption on Ni(100) is studied with S coverages down to 0.08 monolayer. The molecule dissociates at temperatures as low as 100K by interaction with fourfold hollow Ni sites. Blocking of these sites by oxygen leaves the molecule intact

  1. Measurements of ionic structure in shock compressed lithium hydride from ultrafast x-ray Thomson scattering.

    Science.gov (United States)

    Kritcher, A L; Neumayer, P; Brown, C R D; Davis, P; Döppner, T; Falcone, R W; Gericke, D O; Gregori, G; Holst, B; Landen, O L; Lee, H J; Morse, E C; Pelka, A; Redmer, R; Roth, M; Vorberger, J; Wünsch, K; Glenzer, S H

    2009-12-11

    We present the first ultrafast temporally, spectrally, and angularly resolved x-ray scattering measurements from shock-compressed matter. The experimental spectra yield the absolute elastic and inelastic scattering intensities from the measured density of free electrons. Laser-compressed lithium-hydride samples are well characterized by inelastic Compton and plasmon scattering of a K-alpha x-ray probe providing independent measurements of temperature and density. The data show excellent agreement with the total intensity and structure when using the two-species form factor and accounting for the screening of ion-ion interactions.

  2. Covering complete proteomes with X-ray structures: a current snapshot

    Energy Technology Data Exchange (ETDEWEB)

    Mizianty, Marcin J.; Fan, Xiao; Yan, Jing; Chalmers, Eric; Woloschuk, Christopher [University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Joachimiak, Andrzej, E-mail: andrzejj@anl.gov [Argonne National Laboratory, Argonne, IL 60439 (United States); Kurgan, Lukasz, E-mail: andrzejj@anl.gov [University of Alberta, Edmonton, Alberta T6G 2V4 (Canada)

    2014-11-01

    The current and the attainable coverage by X-ray structures of proteins and their functions on the scale of the ‘protein universe’ are estimated. A detailed analysis of the coverage across nearly 2000 proteomes from all superkingdoms of life and functional annotations is performed, with particular focus on the human proteome and the family of GPCR proteins. Structural genomics programs have developed and applied structure-determination pipelines to a wide range of protein targets, facilitating the visualization of macromolecular interactions and the understanding of their molecular and biochemical functions. The fundamental question of whether three-dimensional structures of all proteins and all functional annotations can be determined using X-ray crystallography is investigated. A first-of-its-kind large-scale analysis of crystallization propensity for all proteins encoded in 1953 fully sequenced genomes was performed. It is shown that current X-ray crystallographic knowhow combined with homology modeling can provide structures for 25% of modeling families (protein clusters for which structural models can be obtained through homology modeling), with at least one structural model produced for each Gene Ontology functional annotation. The coverage varies between superkingdoms, with 19% for eukaryotes, 35% for bacteria and 49% for archaea, and with those of viruses following the coverage values of their hosts. It is shown that the crystallization propensities of proteomes from the taxonomic superkingdoms are distinct. The use of knowledge-based target selection is shown to substantially increase the ability to produce X-ray structures. It is demonstrated that the human proteome has one of the highest attainable coverage values among eukaryotes, and GPCR membrane proteins suitable for X-ray structure determination were determined.

  3. Covering complete proteomes with X-ray structures: a current snapshot

    International Nuclear Information System (INIS)

    Mizianty, Marcin J.; Fan, Xiao; Yan, Jing; Chalmers, Eric; Woloschuk, Christopher; Joachimiak, Andrzej; Kurgan, Lukasz

    2014-01-01

    The current and the attainable coverage by X-ray structures of proteins and their functions on the scale of the ‘protein universe’ are estimated. A detailed analysis of the coverage across nearly 2000 proteomes from all superkingdoms of life and functional annotations is performed, with particular focus on the human proteome and the family of GPCR proteins. Structural genomics programs have developed and applied structure-determination pipelines to a wide range of protein targets, facilitating the visualization of macromolecular interactions and the understanding of their molecular and biochemical functions. The fundamental question of whether three-dimensional structures of all proteins and all functional annotations can be determined using X-ray crystallography is investigated. A first-of-its-kind large-scale analysis of crystallization propensity for all proteins encoded in 1953 fully sequenced genomes was performed. It is shown that current X-ray crystallographic knowhow combined with homology modeling can provide structures for 25% of modeling families (protein clusters for which structural models can be obtained through homology modeling), with at least one structural model produced for each Gene Ontology functional annotation. The coverage varies between superkingdoms, with 19% for eukaryotes, 35% for bacteria and 49% for archaea, and with those of viruses following the coverage values of their hosts. It is shown that the crystallization propensities of proteomes from the taxonomic superkingdoms are distinct. The use of knowledge-based target selection is shown to substantially increase the ability to produce X-ray structures. It is demonstrated that the human proteome has one of the highest attainable coverage values among eukaryotes, and GPCR membrane proteins suitable for X-ray structure determination were determined

  4. Tautomerism in quinoxalines derived from the 1,4-naphthoquinone nucleus: acid mediated synthesis, X-ray molecular structure of 5-chlorobenzo[f]quinoxalin-6-ol and density functional theory calculations

    International Nuclear Information System (INIS)

    Gomez, Javier A.G.; Lage, Mateus R.; Carneiro, Jose Walkimar de M.; Resende, Jackson A.L.C.; Vargas, Maria D.

    2013-01-01

    The reaction of tert-butyl 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylamino) ethylcarbamate with CF 3 COOH/CH 2 Cl 2 yields 5-chloro-3,4-dihydrobenzo[f]quinoxalin-6(2H)-one which undergoes acid-promoted dehydrogenation in the presence of water to give novel 5-chlorobenzo[f]quinoxalin-6-ol. The molecular structure of 5-chlorobenzo[f]quinoxalin-6-ol in the solid state, determined by an X-ray diffraction (XRD) study, and the solution data confirm that it exists as the enol-imine tautomer, both in the solid state and in solution, differently from 5-chloro-3,4-dihydrobenzo[f]quinoxalin-6(2H)-one, which exhibits the keto-amine arrangement. Density functional theory (DFT) calculations confirmed the preference of 5-chlorobenzo[f]quinoxalin-6-ol and of the derivatives containing H and CH 3 groups in place of the Cl atom for the enol-imine tautomer. It is suggested that the enol-imine structure is preferred for 5-chlorobenzo[f]quinoxalin-6-ol as a consequence of the higher aromatic character of this structure in comparison with the keto-amine form. DFT calculations carried out on the two tautomers of the benzo[a]phenazin-5(7H)-ones analogous to the benzo[f]quinoxalin-6(4H)-ones showed that the relative stabilities are dominated by solvation effects in the first case and the degree of aromaticity, in the latter. (author)

  5. Tautomerism in quinoxalines derived from the 1,4-naphthoquinone nucleus: acid mediated synthesis, X-ray molecular structure of 5-chlorobenzo[f]quinoxalin-6-ol and density functional theory calculations

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Javier A.G.; Lage, Mateus R.; Carneiro, Jose Walkimar de M.; Resende, Jackson A.L.C.; Vargas, Maria D., E-mail: mdvargas@vm.uff.br, E-mail: walk@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Quimica

    2013-02-15

    The reaction of tert-butyl 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylamino) ethylcarbamate with CF{sub 3}COOH/CH{sub 2}Cl{sub 2} yields 5-chloro-3,4-dihydrobenzo[f]quinoxalin-6(2H)-one which undergoes acid-promoted dehydrogenation in the presence of water to give novel 5-chlorobenzo[f]quinoxalin-6-ol. The molecular structure of 5-chlorobenzo[f]quinoxalin-6-ol in the solid state, determined by an X-ray diffraction (XRD) study, and the solution data confirm that it exists as the enol-imine tautomer, both in the solid state and in solution, differently from 5-chloro-3,4-dihydrobenzo[f]quinoxalin-6(2H)-one, which exhibits the keto-amine arrangement. Density functional theory (DFT) calculations confirmed the preference of 5-chlorobenzo[f]quinoxalin-6-ol and of the derivatives containing H and CH{sub 3} groups in place of the Cl atom for the enol-imine tautomer. It is suggested that the enol-imine structure is preferred for 5-chlorobenzo[f]quinoxalin-6-ol as a consequence of the higher aromatic character of this structure in comparison with the keto-amine form. DFT calculations carried out on the two tautomers of the benzo[a]phenazin-5(7H)-ones analogous to the benzo[f]quinoxalin-6(4H)-ones showed that the relative stabilities are dominated by solvation effects in the first case and the degree of aromaticity, in the latter. (author)

  6. Precision mechanical structure of an ultra-high-resolution spectrometer for inelastic X-ray scattering instrument

    Science.gov (United States)

    Shu, Deming; Shvydko, Yuri; Stoupin, Stanislav A.; Khachatryan, Ruben; Goetze, Kurt A.; Roberts, Timothy

    2015-04-14

    A method and an ultrahigh-resolution spectrometer including a precision mechanical structure for positioning inelastic X-ray scattering optics are provided. The spectrometer includes an X-ray monochromator and an X-ray analyzer, each including X-ray optics of a collimating (C) crystal, a pair of dispersing (D) element crystals, anomalous transmission filter (F) and a wavelength (W) selector crystal. A respective precision mechanical structure is provided with the X-ray monochromator and the X-ray analyzer. The precision mechanical structure includes a base plate, such as an aluminum base plate; positioning stages for D-crystal alignment; positioning stages with an incline sensor for C/F/W-crystal alignment, and the positioning stages including flexure-based high-stiffness structure.

  7. Addressing source-induced structural vibrations in an interventional X-ray system

    NARCIS (Netherlands)

    Van Pinxteren, J.A.W.; Vermeulen, J.P.M.B.; van Loon, R.J.A.; van Schothorst, G.; Billington, D.; Phillips, D.

    2017-01-01

    Interventional radiology is a medical discipline, in which imaging equipment is used to diagnose and treat diseases throughout the human body. Dedicated systems, based on X-ray, computed tomography and ultrasound technology, allow for 2D and 3D imaging of (contrast enhanced) physical structures.

  8. Structural investigation of bistrifluron using x-ray crystallography, NMR spectroscopy, and molecular modeling

    CERN Document Server

    Moon, J K; Rhee, S K; Kim, G B; Yun, H S; Chung, B J; Lee, S S; Lim, Y H

    2002-01-01

    A new insecticide, bistrifluron acts as an inhibitor of insect development and interferes with the cuticle formation of insects. Since it shows low acute oral and dermal toxicities, it can be one of potent insecticides. Based on X-ray crystallography, NMR spectroscopy and molecular modeling, the structural studies of bistrifluron have been carried out.

  9. Analysis of stresses and strains in the materials with limiting structure using x-ray

    International Nuclear Information System (INIS)

    Imafuku, Muneyuki

    2010-01-01

    This review outlines the principle of analysis and the measuring instruments using X-ray for the stresses and strains in the materials with limiting structure. Further the several experimental examples are shown. This method is expected to be useful widely for the characterization evaluation, the reliability insurance, and the development of materials. (M.H.)

  10. The x-ray structure and MNDO calculations of a-terthienyl: a model for polythiophenes

    NARCIS (Netherlands)

    Bolhuis, van F.; Wynberg, H.; Havinga, E.E.; Meijer, E.W.; Staring, E.G.J.

    1989-01-01

    The x-ray structure of a-terthienyl reveals 2 identical, crystallog.-independent mols. in the unit cell. Neighboring thiophene moieties in a-terthienyl are placed antiparallel, while the mol. is almost planar, with torsional angles between the rings of about 6-9 Deg. MNDO calcns. of a-terthienyl

  11. Extended X-ray absorption fine structure investigation of nitrogen stabilized expanded austenite

    DEFF Research Database (Denmark)

    Oddershede, Jette; Christiansen, Thomas; Ståhl, Kenny

    2010-01-01

    As-delivered austenitic stainless steel and nitrogen stabilized expanded austenite, both fully nitrided and denitrided (in H2), were investigated with Cr, Fe and Ni extended X-ray absorption fine structure. The data shows pronounced short-range ordering of Cr and N. For the denitrided specimen...

  12. Grating-based X-ray tomography of 3D food structures

    DEFF Research Database (Denmark)

    Miklos, Rikke; Nielsen, Mikkel Schou; Einarsdottir, Hildur

    2016-01-01

    A novel grating based X-ray phase-contrast tomographic method has been used to study how partly substitution of meat proteins with two different types of soy proteins affect the structure of the formed protein gel in meat emulsions. The measurements were performed at the Swiss synchrotron radiati...

  13. Depth profiling of marker layers using x-ray waveguide structures

    International Nuclear Information System (INIS)

    Gupta, Ajay; Rajput, Parasmani; Saraiya, Amit; Reddy, V. R.; Gupta, Mukul; Bernstorff, Sigrid; Amenitsch, H.

    2005-01-01

    It is demonstrated that x-ray waveguide structures can be used for depth profiling of a marker layer inside the guiding layer with an accuracy of better than 0.2 nm. A combination of x-ray fluorescence and x-ray reflectivity measurements can provide detailed information about the structure of the guiding layer. The position and thickness of the marker layer affect different aspects of the angle-dependent x-ray fluorescence pattern, thus making it possible to determine the structure of the marker layer in an unambiguous manner. As an example, effects of swift heavy ion irradiation on a Si/M/Si trilayer (M=Fe, W), forming the cavity of the waveguide structure, have been studied. It is found that in accordance with the prediction of thermal spike model, Fe is much more sensitive to swift heavy ion induced modifications as compared to W, even in thin film form. However, a clear evidence of movement of the Fe marker layer towards the surface is observed after irradiation, which cannot be understood in terms of the thermal spike model alone

  14. Depth profiling of marker layers using x-ray waveguide structures

    Science.gov (United States)

    Gupta, Ajay; Rajput, Parasmani; Saraiya, Amit; Reddy, V. R.; Gupta, Mukul; Bernstorff, Sigrid; Amenitsch, H.

    2005-08-01

    It is demonstrated that x-ray waveguide structures can be used for depth profiling of a marker layer inside the guiding layer with an accuracy of better than 0.2 nm. A combination of x-ray fluorescence and x-ray reflectivity measurements can provide detailed information about the structure of the guiding layer. The position and thickness of the marker layer affect different aspects of the angle-dependent x-ray fluorescence pattern, thus making it possible to determine the structure of the marker layer in an unambiguous manner. As an example, effects of swift heavy ion irradiation on a Si/M/Si trilayer ( M=Fe , W), forming the cavity of the waveguide structure, have been studied. It is found that in accordance with the prediction of thermal spike model, Fe is much more sensitive to swift heavy ion induced modifications as compared to W, even in thin film form. However, a clear evidence of movement of the Fe marker layer towards the surface is observed after irradiation, which cannot be understood in terms of the thermal spike model alone.

  15. The 1s x-ray absorption pre-edge structures in transition metal oxides

    NARCIS (Netherlands)

    de Groot, Frank|info:eu-repo/dai/nl/08747610X; Vanko, Gyoergy; Glatzel, Pieter

    2009-01-01

    We develop a general procedure to analyse the pre-edges in 1s x-ray absorption near edge structure (XANES) of transition metal oxides and coordination complexes. Transition metal coordination complexes can be described from a local model with one metal ion. The 1s 3d quadrupole transitions are

  16. Stigmasterol from Eichhornia crassipes (water hyacinth) : Isolation, characterization and X-ray structure

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, K.S.; Sawant, S.G.; PrabhaDevi; Kaminsky, W.

    >H48O by combination of NMR and mass spectroscopic data The sterol was fully characterized by FTIR,NMR(1H13C) and mass spectral data Solid state structure of the sterol was determined by single crystal X-Ray diffraction...

  17. Dark-field X-ray microscopy for multiscale structural characterization

    DEFF Research Database (Denmark)

    Simons, Hugh; King, A.; Ludwig, W.

    2015-01-01

    of the interactions between crystalline elements is a key step towards the formulation and validation of multiscale models that account for the entire heterogeneity of a material. Furthermore, dark-field X-ray microscopy is well suited to applied topics, where the structural evolution of internal nanoscale elements...

  18. THE X-RAY STRUCTURE AND THE 13 C NMR DATA OF ...

    African Journals Online (AJOL)

    The alkaloids pellitorine and chelerythrine acetonate were isolated from the stem bark of Zanthoxylum davyi together with methyl octadecyl ketone, lupeol and hesperidin. The alkaloid skimmianie was isolated from the leaves. The X-Ray structure of chelerythrine acetonate was also determined. Key Words: Zanthoxylum ...

  19. Controlled agglomeration of Tb-doped Y2O3 nanocrystals studied by x-ray absorption fine structure, x-ray excited luminescence, and photoluminescence

    International Nuclear Information System (INIS)

    Soo, Y.L.; Huang, S.W.; Kao, Y.H.; Chhabra, V.; Kulkarni, B.; Veliadis, J.V.; Bhargava, R.N.

    1999-01-01

    Local environment surrounding Y atoms in Y 2 O 3 :Tb nanocrystals under various heat treatment conditions has been investigated by using the extended x-ray absorption fine structure (EXAFS) technique. X-ray excited luminescence (XEL) with the incident x-ray energy near Y K edge and Tb L edges has also been measured to investigate the mechanisms of x-ray-to-visible down conversion in these doped nanoparticles. The observed changes in EXAFS, XEL, and photoluminescent data can be explained on the basis of increased average size of the nanoparticles as confirmed by transmission electron microscopy studies. Our results thus demonstrate that the doped nanoparticles can agglomerate to a controllable degree by varying the heat treatment temperature. At higher temperatures, the local environment surrounding Y atoms in the nanoparticles is found to become similar to that in bulk Y 2 O 3 while the XEL output still shows the characteristics of nanocrystals. These results indicate that appropriate heat treatment can afford an effective means to control the intensity and signal-to-background ratio of green luminescence output of these doped nanocrystal phosphors, potentially useful for some device applications. copyright 1999 American Institute of Physics

  20. Characterization of atmospheric aerosols using Synchroton radiation total reflection X-ray fluorescence and Fe K-edge total reflection X-ray fluorescence-X-ray absorption near-edge structure

    Energy Technology Data Exchange (ETDEWEB)

    Fittschen, U.E.A. [Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany)], E-mail: ursula.fittschen@chemie.uni-hamburg.de; Meirer, F. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Wien (Austria)], E-mail: fmeirer@ati.ac.at; Streli, C. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Wien (Austria)], E-mail: streli@ati.ac.at; Wobrauschek, P. [Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Wien (Austria)], E-mail: wobi@ati.ac.at; Thiele, J. [Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany)], E-mail: Julian.Thiele@gmx.de; Falkenberg, G. [Hamburger Synchrotronstrahlungslabor at Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany)], E-mail: falkenbe@mail.desy.de; Pepponi, G. [ITC-irst, Via Sommarive 18, 38050 Povo (Trento) (Italy)], E-mail: pepponi@itc.it

    2008-12-15

    In this study a new procedure using Synchrotron total reflection X-ray fluorescence (SR-TXRF) to characterize elemental amounts in atmospheric aerosols down to particle sizes of 0.015 um is presented. The procedure was thoroughly evaluated regarding bounce off effects and blank values. Additionally the potential of total reflection X-ray fluorescence-X-ray absorption near edge structure (SR-TXRF-XANES) for speciation of FeII/III down to amounts of 34 pg in aerosols which were collected for 1 h is shown. The aerosols were collected in the city of Hamburg with a low pressure Berner impactor on Si carriers covered with silicone over time periods of 60 and 20 min each. The particles were collected in four and ten size fractions of 10.0-8.0 {mu}m, 8.0-2.0 {mu}m, 2.0-0.13 {mu}m 0.13-0.015 {mu}m (aerodynamic particle size) and 15-30 nm, 30-60 nm, 60-130 nm, 130-250 nm, 250-500 nm, 0.5-1 {mu}m, 1-2 {mu}m, 2-4 {mu}m, 4-8 {mu}m, 8-16 {mu}m. Prior to the sampling 'bounce off' effects on Silicone and Vaseline coated Si carriers were studied with total reflection X-ray fluorescence. According to the results silicone coated carriers were chosen for the analysis. Additionally, blank levels originating from the sampling device and the calibration procedure were studied. Blank levels of Fe corresponded to 1-10% of Fe in the aerosol samples. Blank levels stemming from the internal standard were found to be negligible. The results from the Synchroton radiation total reflection X-ray fluorescence analysis of the aerosols showed that 20 min of sampling time gave still enough sample material for elemental determination of most elements. For the determination of the oxidation state of Fe in the aerosols different Fe salts were prepared as a reference from suspensions in isopropanol. The results from the Fe K-edge Synchroton radiation total reflection X-ray fluorescence-X-ray absorption near-edge structure analysis of the aerosol samples showed that mainly Fe(III) was present in

  1. Characterization of atmospheric aerosols using Synchroton radiation total reflection X-ray fluorescence and Fe K-edge total reflection X-ray fluorescence-X-ray absorption near-edge structure

    International Nuclear Information System (INIS)

    Fittschen, U.E.A.; Meirer, F.; Streli, C.; Wobrauschek, P.; Thiele, J.; Falkenberg, G.; Pepponi, G.

    2008-01-01

    In this study a new procedure using Synchrotron total reflection X-ray fluorescence (SR-TXRF) to characterize elemental amounts in atmospheric aerosols down to particle sizes of 0.015 um is presented. The procedure was thoroughly evaluated regarding bounce off effects and blank values. Additionally the potential of total reflection X-ray fluorescence-X-ray absorption near edge structure (SR-TXRF-XANES) for speciation of FeII/III down to amounts of 34 pg in aerosols which were collected for 1 h is shown. The aerosols were collected in the city of Hamburg with a low pressure Berner impactor on Si carriers covered with silicone over time periods of 60 and 20 min each. The particles were collected in four and ten size fractions of 10.0-8.0 μm, 8.0-2.0 μm, 2.0-0.13 μm 0.13-0.015 μm (aerodynamic particle size) and 15-30 nm, 30-60 nm, 60-130 nm, 130-250 nm, 250-500 nm, 0.5-1 μm, 1-2 μm, 2-4 μm, 4-8 μm, 8-16 μm. Prior to the sampling 'bounce off' effects on Silicone and Vaseline coated Si carriers were studied with total reflection X-ray fluorescence. According to the results silicone coated carriers were chosen for the analysis. Additionally, blank levels originating from the sampling device and the calibration procedure were studied. Blank levels of Fe corresponded to 1-10% of Fe in the aerosol samples. Blank levels stemming from the internal standard were found to be negligible. The results from the Synchroton radiation total reflection X-ray fluorescence analysis of the aerosols showed that 20 min of sampling time gave still enough sample material for elemental determination of most elements. For the determination of the oxidation state of Fe in the aerosols different Fe salts were prepared as a reference from suspensions in isopropanol. The results from the Fe K-edge Synchroton radiation total reflection X-ray fluorescence-X-ray absorption near-edge structure analysis of the aerosol samples showed that mainly Fe(III) was present in all particle size fractions

  2. Synthesis, Magnetism, and X-ray Molecular Structure of the Mixed-Valence Vanadium(IV/V)-Oxygen Cluster [VO(4) subset(V(18)O(45))](9-).

    Science.gov (United States)

    Suber, Lorenza; Bonamico, Mario; Fares, Vincenzo

    1997-05-07

    Within the transition metal oxide systems, vanadium presents a unique chemistry due to its capacity to form a great number of mixed-valence oxo clusters which often have the peculiarity to incorporate species that function, for size, shape, and charge, as templates. Prismatic, lustrous dark brown crystals of [(n-C(4)H(9))NH(3)](9)[V(19)O(49)].7H(2)O are obtained by reacting (n-C(4)H(9)NH(3))VO(3), VOSO(4), and (n-C(4)H(9))NH(2) in H(2)O. The X-ray crystal structure shows an ellipsoidal metal-oxo cluster formed by 15 VO(5) and 3 VO(4) polyhedra surrounding an almost regular VO(4) tetrahedron located on the 3-fold axis of a trigonal cell of dimensions a = 19.113(5) Å and c = 13.743(5) Å with space group P&thremacr; and Z = 2. Exponentially weighted bond valence sum calculations, manganometric titration of the V(IV) centers, and magnetic measurements are consistent with the presence of three localized and three delocalized electrons. Variable-temperature solid-state susceptibility studies indicate antiferromagnetic coupling between V(IV) centers. Cyclic voltammetry in acetonitrile shows a irreversible reduction at -1.24 V and a reversible oxidation at +0.17 V (vs Ag/AgCl). The title compound converts quantitatively to the metal oxide K(2)V(3)O(8) with an extended layered structure as soon as a potassium salt is added to a neutral aqueous solution of the polyoxoanion.

  3. Structure analysis of InN film using extended X-ray absorption fine structure method

    Energy Technology Data Exchange (ETDEWEB)

    Miyajima, T.; Kobayashi, T.; Hirata, S. [Core Technology Development Center, Core Technology and Network Company, Sony Corporation, 4-14-1 Asahi-cho, Atsugi, Kanagawa 243-0014 (Japan); Kudo, Y.; Liu, K.L. [Technology Solutions Center, Sony Corporation, 4-16-1 Okata, Atsugi, Kanagawa 243-0021 (Japan); Uruga, T.; Honma, T. [Japan Synchrotron Radiation Research Institute, Mikazuki-cho, Hyogo 679-5198 (Japan); Saito, Y.; Hori, M.; Nanishi, Y. [Department of Photonics, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577 (Japan)

    2002-12-01

    We investigated the local atomic structure around In atoms of MBE-grown InN which has a direct bandgap energy of 0.8 eV, using extended X-ray absorption fine structure (EXAFS) oscillation of In K-edge. The signals from the first-nearest neighbor atoms (N) and second-nearest atoms (In) from In atoms were clearly observed and the atomic bond length of In-N and In-In was estimated to be d{sub In-N}=0.215 nm and d{sub In-In}=0.353 nm, respectively. The In-N bond length of d{sub In-In}=0.353 nm was closed to the a-axis lattice constant of a=0.3536 nm, which was determined using X-ray diffraction measurements. The obtained local atomic structure agreed with the calculated ideal structure. We conclude, therefore, that the InN film with a bandgap energy of 0.8 eV has a high structural symmetry in the range of a few A around In atoms. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  4. Structure analysis of InN film using extended X-ray absorption fine structure method

    International Nuclear Information System (INIS)

    Miyajima, T.; Kobayashi, T.; Hirata, S.; Kudo, Y.; Liu, K.L.; Uruga, T.; Honma, T.; Saito, Y.; Hori, M.; Nanishi, Y.

    2002-01-01

    We investigated the local atomic structure around In atoms of MBE-grown InN which has a direct bandgap energy of 0.8 eV, using extended X-ray absorption fine structure (EXAFS) oscillation of In K-edge. The signals from the first-nearest neighbor atoms (N) and second-nearest atoms (In) from In atoms were clearly observed and the atomic bond length of In-N and In-In was estimated to be d In-N =0.215 nm and d In-In =0.353 nm, respectively. The In-N bond length of d In-In =0.353 nm was closed to the a-axis lattice constant of a=0.3536 nm, which was determined using X-ray diffraction measurements. The obtained local atomic structure agreed with the calculated ideal structure. We conclude, therefore, that the InN film with a bandgap energy of 0.8 eV has a high structural symmetry in the range of a few A around In atoms. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  5. Reactivity and operational stability of N-tailed TAMLs through kinetic studies of the catalyzed oxidation of orange II by H2 O2 : synthesis and X-ray structure of an N-phenyl TAML.

    Science.gov (United States)

    Warner, Genoa R; Mills, Matthew R; Enslin, Clarissa; Pattanayak, Shantanu; Panda, Chakadola; Panda, Tamas Kumar; Gupta, Sayam Sen; Ryabov, Alexander D; Collins, Terrence J

    2015-04-13

    The catalytic activity of the N-tailed ("biuret") TAML (tetraamido macrocyclic ligand) activators [Fe{4-XC6 H3 -1,2-(NCOCMe2 NCO)2 NR}Cl](2-) (3; N atoms in boldface are coordinated to the central iron atom; the same nomenclature is used in for compounds 1 and 2 below), [X, R=H, Me (a); NO2 , Me (b); H, Ph (c)] in the oxidative bleaching of Orange II dye by H2 O2 in aqueous solution is mechanistically compared with the previously investigated activator [Fe{4-XC6 H3 -1,2-(NCOCMe2 NCO)2 CMe2 }OH2 ](-) (1) and the more aggressive analogue [Fe(Me2 C{CON(1,2-C6 H3 -4-X)NCO}2 )OH2 ](-) (2). Catalysis by 3 of the reaction between H2 O2 and Orange II (S) occurs according to the rate law found generally for TAML activators (v=kI kII [Fe(III) ][S][H2 O2 ]/(kI [H2 O2 ]+kII [S]) and the rate constants kI and kII at pH 7 both decrease within the series 3 b>3 a>3 c. The pH dependency of kI and kII was investigated for 3 a. As with all TAML activators studied to-date, bell-shaped profiles were found for both rate constants. For kI , the maximal activity was found at pH 10.7 marking it as having similar reactivity to 1 a. For kII , the broad bell pH profile exhibits a maximum at pH about 10.5. The condition kI ≪kII holds across the entire pH range studied. Activator 3 b exhibits pronounced activity in neutral to slightly basic aqueous solutions making it worthy of consideration on a technical performance basis for water treatment. The rate constants ki for suicidal inactivation of the active forms of complexes 3 a-c were calculated using the general formula ln([S0 ]/[S∞ ])=(kII /ki )[Fe(III) ]; here [Fe(III) ], [S0 ], and [S∞ ] are the total catalyst concentration and substrate concentration at time zero and infinity, respectively. The synthesis and X-ray characterization of 3 c are also described. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Synthesis and H-1 NMR structural analysis of 11-aryl/heteroarylnaphtha[2,1-b]furans : X-ray crystal structure of 11-(4 '-pyridyl)naphtho[2,1-b]furan

    NARCIS (Netherlands)

    Mashraqui, S.H.; Patil, M.B.; Sangvikar, Y.; Ashraf, M.; Mistry, H.D.; Daub, E.T.H.; Meetsma, A.

    2005-01-01

    Synthesis of biaryl type systems, 11-aryl/heteroarylnaphtho[2,1-b]furans 8-11 has been described with a view to studying the conformational orientation of C-11 aryl/heteroaryl groups. Synthesis of 8-11 was accomplished by a two-step sequence involving O-alkylation of 2-naphthol with appropriate

  7. Synthesis of highly stable and biocompatible gold nanoparticles for use as a new X-ray contrast agent.

    Science.gov (United States)

    Iranpour, Pooya; Ajamian, Maral; Safavi, Afsaneh; Iranpoor, Nasser; Abbaspour, Abdolkarim; Javanmardi, Sanaz

    2018-04-18

    This work reports a novel reduction procedure for the synthesis of Gum Arabic (GA) capped-gold nanoparticles (AuNPs) in glucosammonium formate as a new ionic liquid. The GA coated AuNPs show good stability in physiological media. The synthesized AuNPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, dynamic light scattering and X-ray diffraction analysis. These stable AuNPs are introduced as a new contrast agent for X-ray Computed Tomography (X-ray CT). These nanoparticles have higher contrasting properties than the commercial contrast agent, Visipaque. The precursors used (Gum Arabic and glucose based-ionic liquid) for synthesis of AuNPs are biocompatible and non-toxic.

  8. Thermal expansion behavior study of Co nanowire array with in situ x-ray diffraction and x-ray absorption fine structure techniques

    Science.gov (United States)

    Mo, Guang; Cai, Quan; Jiang, Longsheng; Wang, Wei; Zhang, Kunhao; Cheng, Weidong; Xing, Xueqing; Chen, Zhongjun; Wu, Zhonghua

    2008-10-01

    In situ x-ray diffraction and x-ray absorption fine structure techniques were used to study the structural change of ordered Co nanowire array with temperature. The results show that the Co nanowires are polycrystalline with hexagonal close packed structure without phase change up until 700 °C. A nonlinear thermal expansion behavior has been found and can be well described by a quadratic equation with the first-order thermal expansion coefficient of 4.3×10-6/°C and the second-order thermal expansion coefficient of 5.9×10-9/°C. The mechanism of this nonlinear thermal expansion behavior is discussed.

  9. Synthesis and x-ray crystallographic analysis of 4,6-di-O-acetyl-2,3-dideoxy-α-D-threo-hexopyranosyl cyanide.

    Science.gov (United States)

    Rotella, Madeline; Giovine, Matthew; Dougherty, William; Boyko, Walter; Kassel, Scott; Giuliano, Robert

    2016-04-29

    The glycopyranosyl cyanide 4,6-di-O-acetyl-2,3-dideoxy-α-D-threo-hexopyranosyl cyanide has been synthesized from tri-O-acetyl-D-galactal by reaction with trimethylsilyl cyanide in the presence of boron trifluoride diethyl etherate followed by catalytic hydrogenation. The synthesis provides the α-anomer stereoselectively, the structure of which was assigned based on 2D NMR techniques and x-ray crystallography. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Electronic structure of molecules of substituted benzenes by x-ray spectroscopy. I. Nitrobenzene

    International Nuclear Information System (INIS)

    Yumatov, V.D.; Murakhtanov, V.V.; Salakhutdinov, N.F.; Okotrub, A.V.; Mazalov, L.N.; Logunova, L.G.; Koptyug, V.A.; Furin, G.G.

    1988-01-01

    The electronic structure of the nitrobenzene molecule has been studied by x-ray spectroscopy with the aid of quantum-chemical calculations. The structure of the molecular orbitals of nitrobenzene has been compared with the structure of benzene and nitrogen dioxide. It has been shown in the framework of a fragment-by-fragment analysis that the interaction of the highest occupied π orbitals of the benzene ring and the nitro group is weak

  11. Application of the X-ray diffractometer DRON to the study of long period structures

    International Nuclear Information System (INIS)

    Gordelij, V.I.; Lushchikov, V.I.; Syrykh, A.G.; Cherezon, V.G.

    1991-01-01

    It is shown that the stock-produced X-ray diffractometer DRON can be adapted for the study of long period structures up to ∼150 A. The experimental data on small-angle diffraction spectra, measured on it, from both lamellar and lateral structures of biological and lipid membranes are reported. The data show that lattice constants of these structures could be determined within the accuracy of 1 A. 15 refs.; 7 figs

  12. Atomic structure of large angle grain boundaries determined by quantitative X-ray diffraction techniques

    International Nuclear Information System (INIS)

    Fitzsimmons, M.R.; Sass, S.L.

    1988-01-01

    Quantitative X-ray diffraction techniques have been used to determine the atomic structure of the Σ = 5 and 13 [001] twist boundaries in Au with a resolution of 0.09 Angstrom or better. The reciprocal lattices of these boundaries were mapped out using synchrotron radiation. The atomic structures were obtained by testing model structures against the intensity observations with a chi square analysis. The boundary structure were modeled using polyhedra, including octahedra, special configurations of tetrahedra and Archimedian anti-prisms, interwoven together by the boundary symmetry. The results of this work point to the possibility of obtaining general rules for grain boundary structure based on X-ray diffraction observations that give the atomic positions with high resolution

  13. Pollen structure visualization using high-resolution laboratory-based hard X-ray tomography.

    Science.gov (United States)

    Li, Qiong; Gluch, Jürgen; Krüger, Peter; Gall, Martin; Neinhuis, Christoph; Zschech, Ehrenfried

    2016-10-14

    A laboratory-based X-ray microscope is used to investigate the 3D structure of unstained whole pollen grains. For the first time, high-resolution laboratory-based hard X-ray microscopy is applied to study pollen grains. Based on the efficient acquisition of statistically relevant information-rich images using Zernike phase contrast, both surface- and internal structures of pine pollen - including exine, intine and cellular structures - are clearly visualized. The specific volumes of these structures are calculated from the tomographic data. The systematic three-dimensional study of pollen grains provides morphological and structural information about taxonomic characters that are essential in palynology. Such studies have a direct impact on disciplines such as forestry, agriculture, horticulture, plant breeding and biodiversity. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Synthesis and characterization of Bi2S3 composite nanoparticles with high X-ray absorption

    International Nuclear Information System (INIS)

    Huang, Huan-Huan; Chen, Jun; Meng, Yuan-Zheng; Yang, Xiao-Quan; Zhang, Ming-Zhen; Yu, Yong; Ma, Zhi-Ya; Zhao, Yuan-Di

    2013-01-01

    Graphical abstract: - Highlights: • Uniform Bi 2 S 3 nanorods were prepared via a hot injection method. • Bi 2 S 3 nanorods were coated with TEOS and PEG for surface modification. • CT images of Bi 2 S 3 @SiO 2 -PEG are much higher than clinical iobitridol when they have the same concentration. • Cellular toxicity of Bi 2 S 3 @SiO 2 -PEG is low when the probes were directly in contact with tissue fluid. - Abstract: Owing to the high X-ray absorption, Bi 2 S 3 nanocrystals are widely used as CT contrast agents. Here, we prepared uniform Bi 2 S 3 nanorods via a hot injection method using bismuth (III) chloride, sulfur and oleyl amine. The resulting nanocrystals were coated with tetraethylorthosilicate (TEOS) and 2-[methoxy(polyethyleneoxy)propyl]yrimethoxysilane (PEG-silane) for the biological utility. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results showed that the Bi 2 S 3 nanorods had an orthorhombic structure with the length of 14 nm and the diameter of 7 nm, respectively. Composite nanoparticles (0.0226 M) gave a CT number at 550 (HU), which was higher than that of the commercial available iobitridol CT contrast agent. Furthermore, cell experiments revealed that Bi 2 S 3 composite nanoparticles had a low cytotoxicity with a concentration up to 0.01 M of Bi for 24 h

  15. Dual-energy X-ray absorptiometry for the simultaneous determination of Density and Moisture Content in Porous Structural Materials

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Jensen, Signe Kamp; Gerward, Leif

    1999-01-01

    The paper describes the dual-energy x-ray equipment, which consists of a x-ray source, filters and a detector. The x-ray beam can be moved automatically in two dimensions relative to a fixed specimen. The purpose of the equipment is to measure simultaneously the density and moisture content...... in porous materials relevant for the building industry. The theory of dual-energy x-ray absorptiometry (DEXA) is presented. DEXA results on two combinations of aluminium and acrylic plastic are compared with corresponding values calculated from the geometry of the experimental setup. The results from the x......-ray measurements show good agreement with results from the two standard materials which imitate water in a porous material. On this background the dual-energy x-ray absorptiometry measurement principle can be used on porous structural materials....

  16. 3D observation of the solidified structures by x-ray micro computerized tomography

    International Nuclear Information System (INIS)

    Yasuda, Hideyuki; Ohnaka, Itsuo; Tsuchiyama, Akira; Nakano, Tsukasa; Uesugi, Kentaro

    2003-01-01

    The high flux density of the monochromatized and well-collimated X-ray and the high-resolution detector provide a new 3D observation tool for microstructures of metallic alloys and ceramics. The X-ray micro computerized tomography in BL47XU of SPring-8 (SP-μCT) was applied to observe microstructures produced through the eutectic reaction for Sn-based alloys and an Al 2 O 3 -Y 2 O 3 oxide system. The constituent phases in the eutectic structures were three-dimensionally identified, in which the lamellar spacing ranged from several to 10 μm. Since the 3D structure of the unidirectionally solidified specimens contains history of the eutectic structure formation, the 3D structure obtained by SP-μCT gives useful information to consider the microstructure evolution. (author)

  17. Synthesis, X-ray crystallography, and computational analysis of 1-azafenestranes.

    Science.gov (United States)

    Denmark, Scott E; Montgomery, Justin I; Kramps, Laurenz A

    2006-09-06

    The tandem [4+2]/[3+2] cycloaddition of nitroalkenes has been employed in the synthesis of 1-azafenestranes, molecules of theoretical interest because of planarizing distortion of their central carbon atoms. The synthesis of c,c,c,c-[5.5.5.5]-1-azafenestrane was completed in good yield from a substituted nitrocyclopentene, and its borane adduct was analyzed through X-ray crystallography, which showed a moderate distortion from ideal tetrahedral geometry. The syntheses of two members of the [4.5.5.5] family of 1-azafenestranes are also reported, including one with a trans fusion at a bicyclic ring junction which brings about considerable planarization of one of the central angles (16.8 degrees deviation from tetrahedral geometry). While investigating the [4.5.5.5]-1-azafenestranes, a novel dyotropic rearrangement that converts nitroso acetals into tetracyclic aminals was discovered. Through conformational analysis, a means to prevent this molecular reorganization was formulated and realized experimentally with the use of a bulky vinyl ether in the key [4+2] cycloaddition reaction. Finally, DFT calculations on relative strain energy for the 1-azafenestranes, as well as their predicted central angles, are disclosed.

  18. Three dimensional analysis of coelacanth body structure by computer graphics and X-ray CT images

    International Nuclear Information System (INIS)

    Suzuki, Naoki; Hamada, Takashi.

    1990-01-01

    Three dimensional imaging processes were applied for the structural and functional analyses of the modern coelacanth (Latimeria chalumnae). Visualization of the obtained images is performed with computer graphics on the basis of serial images by an X-ray CT scanning method. Reconstruction of three dimensional images of the body structure of coelacanth using the volume rendering and surface rendering methods provides us various information about external and internal shapes of this exquisite fish. (author)

  19. Atomic structure of machined semiconducting chips: An x-ray absorption spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Paesler, M.; Sayers, D.

    1988-12-01

    X-ray absorption spectroscopy (XAS) has been used to examine the atomic structure of chips of germanium that were produced by single point diamond machining. It is demonstrated that although the local (nearest neighbor) atomic structure is experimentally quite similar to that of single crystal specimens information from more distant atoms indicates the presence of considerable stress. An outline of the technique is given and the strength of XAS in studying the machining process is demonstrated.

  20. Sister chromatid exchanges in X-ray irradiated blood lymphocytes from patients with hereditary diseases with radioresistant DNA synthesis

    International Nuclear Information System (INIS)

    Pleskach, N.M.; Andriadze, M.I.; Mikhel'son, V.M.; Zhestyanikov, V.D.

    1988-01-01

    X-ray irradiation induced sister chromatid exchanges (SCE) in blood lymphocytes from patient with Down's syndrome and adult progeria (in both the cases radioresistant DNA synthesis takes place). In normal lymphocytes (in which ionizing radiation inhibits the replicative synthesis of DNA) the rate of SCE rises with the rise of radiation dose. Thus, the rate of SCE in X-ray irradiated lymphocytes is in reverse dependence with radioresistance of replicative synthesis of DNA. The data obtained are explained in accordance with the replicative hypothesis of the SCE nature (Painter, 1980a): in cells of patients with Down's syndrome, xeroderma pigmentosum from 2 and progeria of adults the time of existence of partly replicated clusters of replicons is decreased due to radioresistant replicative synthesis of DNA, but the presence of partly replicated clusters of replicons in necessary for SCE formation. Therefore the rate of SCF in X-irradiated cells of these patients decreases

  1. Magnetic and structural properties of Fe/Pd multilayers studied by magnetic x-ray dichroism and x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Mini, S.M.; Fullerton, E.E.; Sowers, C.H.; Fontaine, A.; Pizzini, S.; Bommannavar, A.S.; Traverse, A.; Baudelet, F.

    1994-12-01

    The results of magnetic circular x-ray dichroism (MCXD) measurements and extended x-ray absorption fine structure measurements (EXAFS) of the Fe K-edges of textured Fe(110)/Pd(111) multilayers are reported. The EXAFS results indicates that the iron in the system goes from bcc to a more densely packed system as the thickness of the iron layer is decreased. The magnetic properties were measured by SQUID magnetometry from 5-350 K. For all the samples, the saturation magnetization was significantly enhanced over the bulk values indicating the interface Pd atoms are polarized by the Fe layer. The enhancement corresponds to a moment of ∼2.5μ B per interface Pd atom

  2. Synchrotron x-ray methods in studies of thin organic film structure

    International Nuclear Information System (INIS)

    Gentle, I.

    2002-01-01

    Full text: In recent years, the study of the structures of organic films as thin as a single monolayer has been revolutionized by methods that take advantage of the characteristics of synchrotron radiation. In particular, the methods of grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity have led to a number of valuable insights into structural aspects of thin films at molecular resolution. Our group has been studying films formed at the air/water interface as insoluble monolayers and subsequently transferred to solid substrates using either the vertical (Langmuir-Blodgett) or horizontal (Langmuir-Schaeffer) methods. The main aim of these experiments is to exert control over film structure in the direction parallel to the substrate surface. This is highly desirable in order to design devices that exploit the optical and electrooptical properties of functional materials, but is difficult to do. By varying the chemical structure of the film materials and controlling deposition conditions a degree of control is possible, but only using synchrotron methods can it be easily verified. We have also developed a novel method of rapidly collecting data from GIXD measurements by the application of area detection (imaging plates), which has made possible measurements of dynamic processes such as in-situ annealing. Such measurements are not possible using traditional scanning methods. One area of current interest is films composed of porphyrins as functional materials, either alone or as mixed films with fatty acids. We have been investigating ways of assembling porphyrins in such a way as to overcome the tendency to aggregate, and to produce patterning and ordered structures in the plane of the interface. Examples will be given of how film composition and deposition method affects the final structure, and of how X-ray methods can be used to elucidate both the structures and the mechanisms. Copyright (2002) Australian X-ray Analytical Association Inc

  3. Structural dissection of human metapneumovirus phosphoprotein using small angle x-ray scattering.

    Science.gov (United States)

    Renner, Max; Paesen, Guido C; Grison, Claire M; Granier, Sébastien; Grimes, Jonathan M; Leyrat, Cédric

    2017-11-01

    The phosphoprotein (P) is the main and essential cofactor of the RNA polymerase (L) of non-segmented, negative-strand RNA viruses. P positions the viral polymerase onto its nucleoprotein-RNA template and acts as a chaperone of the nucleoprotein (N), thereby preventing nonspecific encapsidation of cellular RNAs. The phosphoprotein of human metapneumovirus (HMPV) forms homotetramers composed of a stable oligomerization domain (P core ) flanked by large intrinsically disordered regions (IDRs). Here we combined x-ray crystallography of P core with small angle x-ray scattering (SAXS)-based ensemble modeling of the full-length P protein and several of its fragments to provide a structural description of P that captures its dynamic character, and highlights the presence of varyingly stable structural elements within the IDRs. We discuss the implications of the structural properties of HMPV P for the assembly and functioning of the viral transcription/replication machinery.

  4. Structure of liposome encapsulating proteins characterized by X-ray scattering and shell-modeling

    International Nuclear Information System (INIS)

    Hirai, Mitsuhiro; Kimura, Ryota; Takeuchi, Kazuki; Hagiwara, Yoshihiko; Kawai-Hirai, Rika; Ohta, Noboru; Igarashi, Noriyuki; Shimuzu, Nobutaka

    2013-01-01

    Wide-angle X-ray scattering data using a third-generation synchrotron radiation source are presented. Lipid liposomes are promising drug delivery systems because they have superior curative effects owing to their high adaptability to a living body. Lipid liposomes encapsulating proteins were constructed and the structures examined using synchrotron radiation small- and wide-angle X-ray scattering (SR-SWAXS). The liposomes were prepared by a sequential combination of natural swelling, ultrasonic dispersion, freeze-throw, extrusion and spin-filtration. The liposomes were composed of acidic glycosphingolipid (ganglioside), cholesterol and phospholipids. By using shell-modeling methods, the asymmetric bilayer structure of the liposome and the encapsulation efficiency of proteins were determined. As well as other analytical techniques, SR-SWAXS and shell-modeling methods are shown to be a powerful tool for characterizing in situ structures of lipid liposomes as an important candidate of drug delivery systems

  5. Stereoselective synthesis, X-ray analysis, computational studies and biological evaluation of new thiazole derivatives as potential anticancer agents.

    Science.gov (United States)

    Mabkhot, Yahia N; Alharbi, Mohammed M; Al-Showiman, Salim S; Ghabbour, Hazem A; Kheder, Nabila A; Soliman, Saied M; Frey, Wolfgang

    2018-05-11

    The synthesis of new thiazole derivatives is very important because of their diverse biological activities. Also , many drugs containing thiazole ring in their skeletons are available in the market such as Abafungin, Acotiamide, Alagebrium, Amiphenazole, Brecanavir, Carumonam, Cefepime, and Cefmatilen. Ethyl cyanoacetate reacted with phenylisothiocyanate, chloroacetone, in two different basic mediums to afford the thiazole derivative 6, which reacted with dimethylformamide- dimethyl acetal in the presence of DMF to afford the unexpected thiazole derivative 11. The structures of the thiazoles 6 and 11 were optimized using B3LYP/6-31G(d,p) method. The experimentally and theoretically geometric parameters agreed very well. Also, the natural charges at the different atomic sites were predicted. HOMO and LUMO demands were discussed. The anticancer activity of the prepared compounds was evaluated and showed moderate activity. Synthesis of novel thiazole derivatives was done. The structure was established using X-ray and spectral analysis. Optimized molecular structures at the B3LYP/6-31G(d,p) level were investigated. Thiazole derivative 11 has more electropositive S-atom than thiazole 6. The HOMO-LUMO energy gap is lower in the former compared to the latter. The synthesized compounds showed moderate anticancer activity.

  6. The structural analysis of zinc borate glass by laboratory EXAFS and X-ray diffraction measurements

    International Nuclear Information System (INIS)

    Kajinami, Akihiko; Harada, Yasushi; Inoue, Shinsuke; Deki, Shigehito; Umesaki, Norimasa

    1999-01-01

    The structure of zinc borate glass has been investigated by laboratory EXAFS and X-ray diffraction measurement as preliminary investigations for the detailed study in SPring-8. The zinc borate glass was prepared in the range from 40 to 65 mol% of zinc oxide content. The X-ray diffraction was measured by horizontal θ-θ goniometer with 60 kV and 300 mA output of Mo target. The EXAFS of zinc borate glass was measured by laboratory EXAFS system with 20 kV, 100 mA output of Mo target for the K absorption edge of zinc atom. From the X-ray diffraction and the EXAFS measurements, it is found that the zinc ion is surrounded by four oxygen atoms and formed a tetrahedral structure whose (Zn-O) distance is about 2 A and that the structure is unchanged with the zinc oxide content. The diffraction data show that the neighboring structure of boron atom transforms from BO 4 tetrahedra to BO 3 tetragonal planar structure with increasing of the zinc oxide content. (author)

  7. Synthesis, X-ray crystallography, thermal studies, spectroscopic and electrochemistry investigations of uranyl Schiff base complexes.

    Science.gov (United States)

    Asadi, Zahra; Shorkaei, Mohammad Ranjkesh

    2013-03-15

    Some tetradentate salen type Schiff bases and their uranyl complexes were synthesized and characterized by UV-Vis, NMR, IR, TG, C.H.N. and X-ray crystallographic studies. From these investigations it is confirmed that a solvent molecule occupied the fifth position of the equatorial plane of the distorted pentagonal bipyramidal structure. Also, the kinetics of complex decomposition by using thermo gravimetric methods (TG) was studied. The thermal decomposition reactions are first order for the studied complexes. To examine the properties of uranyl complexes according to the substitutional groups, we have carried out the electrochemical studies. The electrochemical reactions of uranyl Schiff base complexes in acetonitrile were reversible. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Ethyl 2,6-Dimethoxybenzoate: Synthesis, Spectroscopic and X-ray Crystallographic Analysis

    Directory of Open Access Journals (Sweden)

    Jonathan M. White

    2012-05-01

    Full Text Available The acid catalyzed esterification of 2,6-dimethoxybenzoic acid (1 in the presence of absolute ethanol afforded ethyl 2, 6-dimethoxybenzoate (2. The structure of the resulting compound was supported by spectroscopic data and unambiguously confirmed by single crystal X-ray diffraction studies. The title compound crystallized in the triclinic space group P ī with unit cell parameters a = 8.5518(3 Å, b = 10.8826(8 Å, c = 11.9939(6 Å, α = 101.273(5°, β = 98.287(3°, γ = 94.092(4°, V = 1077.54(10 Å3, Z = 4, Dc = 1.296 Mg/m3, F(000 = 448 and μ = 0.098 mm−1. Compound (2 crystallizes with two molecules in the asymmetric unit with similar conformations.

  9. Integrative structural modeling with small angle X-ray scattering profiles

    Directory of Open Access Journals (Sweden)

    Schneidman-Duhovny Dina

    2012-07-01

    Full Text Available Abstract Recent technological advances enabled high-throughput collection of Small Angle X-ray Scattering (SAXS profiles of biological macromolecules. Thus, computational methods for integrating SAXS profiles into structural modeling are needed more than ever. Here, we review specifically the use of SAXS profiles for the structural modeling of proteins, nucleic acids, and their complexes. First, the approaches for computing theoretical SAXS profiles from structures are presented. Second, computational methods for predicting protein structures, dynamics of proteins in solution, and assembly structures are covered. Third, we discuss the use of SAXS profiles in integrative structure modeling approaches that depend simultaneously on several data types.

  10. X-ray refractive index: A tool to determine the average composition in multilayer structures

    International Nuclear Information System (INIS)

    Miceli, P.F.; Neumann, D.A.; Zabel, H.

    1986-01-01

    We present a novel and simple method to determine the average composition of multilayers and superlattices by measuring the x-ray refractive index. Since these modulated structures exhibit Bragg reflections at small angles, by using a triple axis x-ray spectrometer we have accurately determined the peak shifts due to refraction in GaAs/Al/sub x/Ga/sub 1-x/As and Nb/Ta superlattices. Knowledge of the refractive index provides the average fractional composition of the periodic structure since the refractive index is a superposition of the refractive indices of the atomic constituents. We also present a critical discussion of the method and compare the values of the average fractional composition obtained in this manner to the values obtained from the lattice parameter change in the GaAs/Al/sub x/Ga/sub 1-x/As superlattices due to the Al

  11. Structured photocathodes for improved high-energy x-ray efficiency in streak cameras

    Energy Technology Data Exchange (ETDEWEB)

    Opachich, Y. P., E-mail: opachiyp@nv.doe.gov; Huffman, E.; Koch, J. A. [National Security Technologies, LLC, Livermore, California 94551 (United States); Bell, P. M.; Bradley, D. K.; Hatch, B.; Landen, O. L.; MacPhee, A. G.; Nagel, S. R. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Chen, N.; Gopal, A.; Udin, S. [Nanoshift LLC, Emeryville, California 94608 (United States); Feng, J. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Hilsabeck, T. J. [General Atomics, San Diego, California 92121 (United States)

    2016-11-15

    We have designed and fabricated a structured streak camera photocathode to provide enhanced efficiency for high energy X-rays (1–12 keV). This gold coated photocathode was tested in a streak camera and compared side by side against a conventional flat thin film photocathode. Results show that the measured electron yield enhancement at energies ranging from 1 to 10 keV scales well with predictions, and that the total enhancement can be more than 3×. The spatial resolution of the streak camera does not show degradation in the structured region. We predict that the temporal resolution of the detector will also not be affected as it is currently dominated by the slit width. This demonstration with Au motivates exploration of comparable enhancements with CsI and may revolutionize X-ray streak camera photocathode design.

  12. X-ray diffuse scattering effects from Coulomb-type defects in multilayered structures

    International Nuclear Information System (INIS)

    Olikhovskii, S.I.; Molodkin, V.B.; Skakunova, E.S.; Kislovskii, E.N.; Fodchuk, I.M.

    2009-01-01

    The theoretical X-ray diffraction model starting from Takagi-Taupin equation has been developed for the description of coherent and diffuse components of the rocking curve (RC) measured from the multilayered crystal structure with randomly distributed Coulomb-type defects in all the layers and substrate. The model describes both diffuse scattering (DS) intensity distribution and influence of DS on attenuation and angular redistribution of the coherent X-ray scattering intensity. By analyzing the total measured RC with using the proposed diffraction model, the chemical compositions, strains, and characteristics of dislocation loops in layers and substrate of the multilayered structure with InGaAsN/GaAs single quantum well have been determined. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  13. Soft x-ray measurement of internal tearing mode structure in a reversed-field pinch

    International Nuclear Information System (INIS)

    Chartas, G.; Hokin, S.

    1991-01-01

    The structure of internally resonant tearing modes has been studied in the Madison Symmetric Torus reversed-field pinch with a soft x-ray detector system consisting of an imaging array at one toroidal location and several detectors at different toroidal locations. The toroidal mode numbers of m = 1 structures are in the range n = -5, -6, -7. The modes propagate with phase velocity v = 1--6 x 10 6 cm/s, larger than the diamagnetic drift velocity v d ∼ 5 x 10 5 cm/s. Phase locking between modes with different n in manifested as a beating of soft x-ray signals which is found to be strongest near the resonant surfaces of the modes (r/a = 0.1 -- 0.5). 15 refs., 5 figs

  14. Structural characterization of oxidized allotaxially grown CoSi2 layers by x-ray scattering

    International Nuclear Information System (INIS)

    Kaendler, I. D.; Seeck, O. H.; Schlomka, J.-P.; Tolan, M.; Press, W.; Stettner, J.; Kappius, L.; Dieker, C.; Mantl, S.

    2000-01-01

    A series of buried CoSi 2 layers prepared by a modified molecular beam epitaxy process (allotaxy) and a subsequent wet-oxidation process was investigated by x-ray scattering. The oxidation time which determines the depth in which the CoSi 2 layers are located within the Si substrates has been varied during the preparation. The electron density profiles and the structure of the interfaces were extracted from specular reflectivity and diffuse scattering measurements. Crystal truncation rod investigations yielded the structure on an atomic level (crystalline quality). It turns out that the roughness of the CoSi 2 layers increases drastically with increasing oxidation time, i.e., with increasing depth of the buried layers. Furthermore, the x-ray data reveal that the oxidation growth process is diffusion limited. (c) 2000 American Institute of Physics

  15. Structural and microstructural characterization of U3Si2 nuclear fuel using X-ray diffraction

    International Nuclear Information System (INIS)

    Ichikawa, Rodrigo U.; Garcia, Rafael H.L.; Silva, Andre S.B. da; Saliba-Silva, Adonis M.; Lima, Nelson B.; Martinez, Luis G.; Turrillas, Xavier

    2017-01-01

    In this work, two uranium silicide powdered samples, containing 67% and 42 mol% of Si, were analyzed using X-ray diffraction (named as 67 Si and 42 Si). For structural characterization, Rietveld refinement was used to estimate cell parameters, volume fraction (weight percent) of crystalline phases and atomic positions. For the main phases, X-ray line profile analysis (XLPA) was used to estimate mean crystallite sizes and micro strains. The 67 Si sample presents higher content of USi 2( tetragonal) and the 42 Si sample presents higher content of U 3 Si 2 (tetragonal) as identified and calculated from the XRD profiles. Overall there are no appreciable structural changes and the parameters refined are in good accordance with the ones reported in the literature. Mean crystallite sizes determined by XLPA revealed small crystallites of the order of 10 1 nm and low micro strain for all samples. (author)

  16. Single crystal X-ray structure of the artists' pigment zinc yellow

    Science.gov (United States)

    Simonsen, Kim Pilkjær; Christiansen, Marie Bitsch; Vinum, Morten Gotthold; Sanyova, Jana; Bendix, Jesper

    2017-08-01

    The artists' pigment zinc yellow is in general described as a complex potassium zinc chromate with the empirical formula 4ZnCrO4·K2O·3H2O. Even though the pigment has been in use since the second half of the 19th century also in large-scale industrial applications, the exact structure had hitherto been unknown. In this work, zinc yellow was synthesised by precipitation from an aqueous solution of zinc nitrate and potassium chromate under both neutral and basic conditions, and the products were compared with the pigment used in industrial paints. Analyses by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and powder X-ray diffraction (PXRD), showed that the synthesised products and the industrial pigment were identical. Single-crystal X-ray crystallography determined the structure of zinc yellow as KZn2(CrO4)2(H2O)(OH) or as KZn2(CrO4)2(H3O2) emphasizing the μ-H3O2- moiety. Notably, the zinc yellow is isostructural to the recently structurally characterized cadmium analog and both belong to the natrochalcite structure type.

  17. Structural shielding of medical X-ray rooms for diagnostic installations

    International Nuclear Information System (INIS)

    Rabitsch, H.

    1979-06-01

    In Part I (RIG 8), the various design procedures for shielding against X-rays are discussed and compared. In particular, this comparison is carried out between the shielding obtained conforming to the Austrian Regulations for Radiation Protection and that obtained from the DIN-standard DIN 6812; this latter includes the various operating conditions of diagnostic installations up to 150 kV. Several examples for particular structural shielding components in medical radiation rooms are given. (author)

  18. single crystal growth, x-ray structure analysis, optical band gap

    African Journals Online (AJOL)

    2015-09-01

    Sep 1, 2015 ... Hg...Hgand Cl...Cl interactions are stabilizing the structures in 3D pattern. UV-vis absorption spectra illustrate the change in opticalband gap from 3.01eVto 3.42eV on replacing the metal halide group.Raman and Hyper-Raman tensors calculations were performed based on single crystal X-ray data and the ...

  19. Structural transformation of compressed solid Ar: An x-ray diffraction study to 114 GPa

    International Nuclear Information System (INIS)

    Errandonea, D.; Boehler, R.; Japel, S.; Mezouar, M.; Benedetti, L. R.

    2006-01-01

    Room temperature angle-dispersive x-ray diffraction measurements on solid Ar up to 114 GPa reveal evidence of a structural phase transformation after stress relaxation by laser heating. Beyond 49.6 GPa, Ar exhibits the coexistence of fcc and hcp phases with an increasing hcp/fcc ratio, similar to the observation made recently on krypton and xenon. From the present results, we estimate the fcc-to-hcp transition to be completed at 300 GPa

  20. Total reflection X-ray fluorescence analysis with synchrotron radiation monochromatized by multilayer structures

    International Nuclear Information System (INIS)

    Rieder, R.; Wobrauschek, P.; Ladisich, W.; Streli, C.; Aiginger, H.; Garbe, S.; Gaul, G.; Knoechel, A.; Lechtenberg, F.

    1995-01-01

    To achieve lowest detection limits in total reflection X-ray fluorescence analysis (TXRF) synchrotron radiation has been monochromatized by a multilayer structure to obtain a relative broad energy band compared to Bragg single crystals for an efficient excitation. The energy has been set to 14 keV, 17.5 keV, 31 keV and about 55 keV. Detection limits of 20 fg and 150 fg have been achieved for Sr and Cd, respectively. ((orig.))

  1. Study of the argyrophil structures of thymus connective tissue after exposure to X-rays

    International Nuclear Information System (INIS)

    Beletskij, V.K.; Beletskaya, L.V.; Akademiya Meditsinskikh Nauk SSSR, Moscow. Inst. Ehpidemiologii i Mikrobiologii)

    1980-01-01

    Studied are argyrophil structures of thymus connective tissue - histiocytes (appendiculate macrophages) and reticuline fibers after the bulk of lymphoid cells has migrated from the organ due to irradiation of animals with X-rays. 10 intact and 16 experimental guinea pigs subjected to the whole-body irradiation with X-rays in the dose of 1000-3000 rad have been used for investigations. It is shown that argyrophil stroma elements of thymus connective tissue, histiocytes and reticular cells, are rather resistant to X-rays and preserve their argyrophily property in the irradiation with high doses, as well as the epithelial cells of the organ. Paraplastic structures in irradiated animals are expressed more completely being demasked as a result of lymphocyte migration and death. The expressed hypertrophy and proliferation of reticular cells and appendiculate macrophages are probably the response to the alternative process in the organ tissues caused by irradiation. A close structural connection of reticular and epithelial tissues on the territory of both layers of thymus sections is noted

  2. Structural Modification of Cobalt Catalysts: Effect of Wetting Studied by X-Ray and Infrared Techniques

    Directory of Open Access Journals (Sweden)

    Khodakov A.

    1999-07-01

    Full Text Available The effect of wetting on the structure and localisation of cobalt species on various supports (Al2O3, SiO2, TiO2, HZSM-5 zeolite was studied using X-ray diffraction, Fourier transform infrared spectroscopy with CO as a molecular probe, X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis. Aqueous impregnation to incipient wetness of reduced and passivated cobalt catalysts results, even in the absence of any promoter, in a considerable decrease in the concentration of Co crystalline phases and modifies the surface sites. The decrease in the concentration of Co3O4 crystallites was especially pronounced on silica supported catalysts prepared via impregnation of cobalt and on a mixture of Co3O4 and HZSM-5 zeolite. Saturation with water of the passivated Co/SiO2 sample results in an amorphous solid with a local structure close to that of Co2SiO4. For Co/Al2O3 and Co/TiO2 catalysts, the effect of wetting on the concentration of Co3O4 crystalline phase was considerably smaller.

  3. Fluoride ion donor properties of cis-OsO(2)F(4): synthesis, raman spectroscopic study, and X-ray crystal structure of [OsO(2)F(3)][Sb(2)F(11)].

    Science.gov (United States)

    Hughes, Michael J; Mercier, Hélène P A; Schrobilgen, Gary J

    2010-01-04

    The salt, [OsO(2)F(3)][Sb(2)F(11)], has been synthesized by dissolution of cis-OsO(2)F(4) in liquid SbF(5), followed by removal of excess SbF(5) at 0 degrees C to yield orange, crystalline [OsO(2)F(3)][Sb(2)F(11)]. The X-ray crystal structure (-173 degrees C) consists of an OsO(2)F(3)(+) cation fluorine bridged to an Sb(2)F(11)(-) anion. The light atoms of OsO(2)F(3)(+) and the bridging fluorine atom form a distorted octahedron around osmium in which the osmium atom is displaced from its center toward an oxygen atom and away from the trans-fluorine bridge atom. As in other transition metal dioxofluorides, the oxygen ligands are cis to one another and the fluorine bridge atom is trans to an oxygen ligand and cis to the remaining oxygen ligand. The Raman spectrum (-150 degrees C) of solid [OsO(2)F(3)][Sb(2)F(11)] was assigned on the basis of the ion pair observed in the low-temperature crystal structure. Under dynamic vacuum, [OsO(2)F(3)][Sb(2)F(11)] loses SbF(5), yielding the known [mu-F(OsO(2)F(3))(2)][Sb(2)F(11)] salt with no evidence for [OsO(2)F(3)][SbF(6)] formation. Attempts to synthesize [OsO(2)F(3)][SbF(6)] by the reaction of [OsO(2)F(3)][Sb(2)F(11)] with an equimolar amount of cis-OsO(2)F(4) or by a 1:1 stoichiometric reaction of cis-OsO(2)F(4) with SbF(5) in anhydrous HF yielded only [mu-F(OsO(2)F(3))(2)][Sb(2)F(11)]. Quantum-chemical calculations at the SVWN and B3LYP levels of theory and natural bond orbital analyses were used to calculate the gas-phase geometries, vibrational frequencies, natural population analysis charges, bond orders, and valencies of OsO(2)F(3)(+), [OsO(2)F(3)][Sb(2)F(11)], [OsO(2)F(3)][SbF(6)], and Sb(2)F(11)(-). The relative thermochemical stabilities of [OsO(2)F(3)][SbF(6)], [OsO(2)F(3)][Sb(2)F(11)], [OsO(2)F(3)][AsF(6)], [mu-F(OsO(2)F(3))(2)][SbF(6)], [mu-F(OsO(2)F(3))(2)][Sb(2)F(11)], and [mu-F(OsO(2)F(3))(2)][AsF(6)] were assessed using the appropriate Born-Haber cycles to account for the preference for [mu-F(OsO(2)F(3

  4. Population synthesis and x-ray properties of passively evolving galaxies

    International Nuclear Information System (INIS)

    Renzini, A.

    1989-01-01

    In this review some evolutionary processes in galaxies will be considered which may be less exciting than other phenomena such as starburst activities, galactic interactions, merging, or cannibalism. The discussion will rather be restricted to passively evolving stellar populations, i.e. to what may happen when all giant molecular clouds have blown away, when every shower of star formation has ceased, and stars just shine, age, and eventually die. Only this passive evolution is in fact subject to laws that - at least in principle - can be rigorously formulated, while star formation processes, because of the prominent role played by chaotic hydrodynamics, rather resemble meteorological events. In Section 2 some fundamental properties of simple stellar populations are introduced. These can be regarded as the basic laws controlling the evolution of stellar populations, once that they have condensed from the diffused medium. In Section 3 the primary requirements that acceptable evolutionary population synthesis should fulfil are then briefly recalled, and, finally, in Section 4 some of the basic laws are put at play in an attempt to discuss the evolution over cosmological times of the X-ray properties of elliptical galaxies. (author)

  5. Predicting X-ray diffuse scattering from translation–libration–screw structural ensembles

    International Nuclear Information System (INIS)

    Van Benschoten, Andrew H.; Afonine, Pavel V.; Terwilliger, Thomas C.; Wall, Michael E.; Jackson, Colin J.; Sauter, Nicholas K.; Adams, Paul D.; Urzhumtsev, Alexandre; Fraser, James S.

    2015-01-01

    A method of simulating X-ray diffuse scattering from multi-model PDB files is presented. Despite similar agreement with Bragg data, different translation–libration–screw refinement strategies produce unique diffuse intensity patterns. Identifying the intramolecular motions of proteins and nucleic acids is a major challenge in macromolecular X-ray crystallography. Because Bragg diffraction describes the average positional distribution of crystalline atoms with imperfect precision, the resulting electron density can be compatible with multiple models of motion. Diffuse X-ray scattering can reduce this degeneracy by reporting on correlated atomic displacements. Although recent technological advances are increasing the potential to accurately measure diffuse scattering, computational modeling and validation tools are still needed to quantify the agreement between experimental data and different parameterizations of crystalline disorder. A new tool, phenix.diffuse, addresses this need by employing Guinier’s equation to calculate diffuse scattering from Protein Data Bank (PDB)-formatted structural ensembles. As an example case, phenix.diffuse is applied to translation–libration–screw (TLS) refinement, which models rigid-body displacement for segments of the macromolecule. To enable the calculation of diffuse scattering from TLS-refined structures, phenix.tls-as-xyz builds multi-model PDB files that sample the underlying T, L and S tensors. In the glycerophosphodiesterase GpdQ, alternative TLS-group partitioning and different motional correlations between groups yield markedly dissimilar diffuse scattering maps with distinct implications for molecular mechanism and allostery. These methods demonstrate how, in principle, X-ray diffuse scattering could extend macromolecular structural refinement, validation and analysis

  6. Predicting X-ray diffuse scattering from translation–libration–screw structural ensembles

    Energy Technology Data Exchange (ETDEWEB)

    Van Benschoten, Andrew H. [University of California San Francisco, San Francisco, CA 94158 (United States); Afonine, Pavel V. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Terwilliger, Thomas C.; Wall, Michael E. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Jackson, Colin J. [Australian National University, Canberra, ACT 2601 (Australia); Sauter, Nicholas K. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Adams, Paul D. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); University of California Berkeley, Berkeley, CA 94720 (United States); Urzhumtsev, Alexandre [Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS–INSERM–UdS, 1 Rue Laurent Fries, BP 10142, 67404 Illkirch (France); Université de Lorraine, BP 239, 54506 Vandoeuvre-les-Nancy (France); Fraser, James S., E-mail: james.fraser@ucsf.edu [University of California San Francisco, San Francisco, CA 94158 (United States)

    2015-07-28

    A method of simulating X-ray diffuse scattering from multi-model PDB files is presented. Despite similar agreement with Bragg data, different translation–libration–screw refinement strategies produce unique diffuse intensity patterns. Identifying the intramolecular motions of proteins and nucleic acids is a major challenge in macromolecular X-ray crystallography. Because Bragg diffraction describes the average positional distribution of crystalline atoms with imperfect precision, the resulting electron density can be compatible with multiple models of motion. Diffuse X-ray scattering can reduce this degeneracy by reporting on correlated atomic displacements. Although recent technological advances are increasing the potential to accurately measure diffuse scattering, computational modeling and validation tools are still needed to quantify the agreement between experimental data and different parameterizations of crystalline disorder. A new tool, phenix.diffuse, addresses this need by employing Guinier’s equation to calculate diffuse scattering from Protein Data Bank (PDB)-formatted structural ensembles. As an example case, phenix.diffuse is applied to translation–libration–screw (TLS) refinement, which models rigid-body displacement for segments of the macromolecule. To enable the calculation of diffuse scattering from TLS-refined structures, phenix.tls-as-xyz builds multi-model PDB files that sample the underlying T, L and S tensors. In the glycerophosphodiesterase GpdQ, alternative TLS-group partitioning and different motional correlations between groups yield markedly dissimilar diffuse scattering maps with distinct implications for molecular mechanism and allostery. These methods demonstrate how, in principle, X-ray diffuse scattering could extend macromolecular structural refinement, validation and analysis.

  7. Transmission X-ray scattering as a probe for complex liquid-surface structures

    Energy Technology Data Exchange (ETDEWEB)

    Fukuto, Masafumi; Yang, Lin; Nykypanchuk, Dmytro; Kuzmenko, Ivan

    2016-01-28

    The need for functional materials calls for increasing complexity in self-assembly systems. As a result, the ability to probe both local structure and heterogeneities, such as phase-coexistence and domain morphologies, has become increasingly important to controlling self-assembly processes, including those at liquid surfaces. The traditional X-ray scattering methods for liquid surfaces, such as specular reflectivity and grazing-incidence diffraction, are not well suited to spatially resolving lateral heterogeneities due to large illuminated footprint. A possible alternative approach is to use scanning transmission X-ray scattering to simultaneously probe local intermolecular structures and heterogeneous domain morphologies on liquid surfaces. To test the feasibility of this approach, transmission small- and wide-angle X-ray scattering (TSAXS/TWAXS) studies of Langmuir films formed on water meniscus against a vertically immersed hydrophilic Si substrate were recently carried out. First-order diffraction rings were observed in TSAXS patterns from a monolayer of hexagonally packed gold nanoparticles and in TWAXS patterns from a monolayer of fluorinated fatty acids, both as a Langmuir monolayer on water meniscus and as a Langmuir–Blodgett monolayer on the substrate. The patterns taken at multiple spots have been analyzed to extract the shape of the meniscus surface and the ordered-monolayer coverage as a function of spot position. These results, together with continual improvement in the brightness and spot size of X-ray beams available at synchrotron facilities, support the possibility of using scanning-probe TSAXS/TWAXS to characterize heterogeneous structures at liquid surfaces.

  8. PREFACE: Structure and dynamics determined by neutron and x-ray scattering Structure and dynamics determined by neutron and x-ray scattering

    Science.gov (United States)

    Müller-Buschbaum, Peter

    2011-06-01

    Neutron and x-ray scattering have emerged as powerful methods for the determination of structure and dynamics. Driven by emerging new, powerful neutron and synchrotron radiation sources, the continuous development of new instrumentation and novel scattering techniques gives rise to exciting possibilities. For example, in situ observations become possible via a high neutron or x-ray flux at the sample and, as a consequence, morphological transitions with small time constants can be detected. This special issue covers a broad range of different materials from soft to hard condensed matter. Hence, different material classes such as colloids, polymers, alloys, oxides and metals are addressed. The issue is dedicated to the 60th birthday of Professor Winfried Petry, scientific director of the Research Neutron Source Heinz Maier-Leibnitz (FRM-II), Germany, advisor at the physics department for the Bayerische Elite-Akademie, chair person of the Arbeitsgemeinschaft Metall- und Materialphysik of the German Physical Society (DPG) and a member of the professional council of the German Science Foundation (Deutsche Forschungsgemeinschaft, DFG). We would like to acknowledge and thank all contributors for their submissions, which made this special issue possible in the first place. Moreover, we would like to thank the staff at IOP Publishing for helping us with the administrative aspects and for coordinating the refereeing process, and Valeria Lauter for the beautiful cover artwork. Finally, to the readers, we hope that you find this special issue a valuable resource that provides insights into the present possibilities of neutron and x-ray scattering as powerful tools for the investigation of structure and dynamics. Structure and dynamics determined by neutron and x-ray scattering contents In situ studies of mass transport in liquid alloys by means of neutron radiography F Kargl, M Engelhardt, F Yang, H Weis, P Schmakat, B Schillinger, A Griesche and A Meyer Magnetic spin

  9. X-ray photoemission electron microscopy, a tool for the investigation of complex magnetic structures

    International Nuclear Information System (INIS)

    Scholl, Andreas; Ohldag, Hendrik; Nolting, Frithjof; Stohr, Joachim; Padmore, Howard A.

    2001-01-01

    X-ray Photoemission Electron Microscopy unites the chemical specificity and magnetic sensitivity of soft x-ray absorption techniques with the high spatial resolution of electron microscopy. The discussed instrument possesses a spatial resolution of better than 50 nm and is located at a bending magnet beamline at the Advanced Light Source, providing linearly and circularly polarized radiation between 250 and 1300 eV. We will present examples which demonstrate the power of this technique applied to problems in the field of thin film magnetism. The chemical and elemental specificity is of particular importance for the study of magnetic exchange coupling because it allows separating the signal of the different layers and interfaces in complex multi-layered structures

  10. Template assisted self-assembly of iron oxide nanoparticles: An x-ray structural analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, D. [Department of Physics, Ruhr-University Bochum, 44780 Bochum (Germany); Institut fuer Optik und Atomare Physik, Technische Universitaet Berlin, Strasse des 17. Juni 135, 10623 Berlin (Germany); Zabel, H. [Department of Physics, Ruhr-University Bochum, 44780 Bochum (Germany); Ulyanov, S. V. [St.-Petersburg State University, Ul' yanovskaya ul.1, Petrodvorets, St.-Petersburg 198904 (Russian Federation); St.-Petersburg University of Commerce and Economics, St.-Petersburg 194018 (Russian Federation); Romanov, V. P. [St.-Petersburg State University, Ul' yanovskaya ul.1, Petrodvorets, St.-Petersburg 198904 (Russian Federation); Uzdin, V. M. [St.-Petersburg State University, Ul' yanovskaya ul.1, Petrodvorets, St.-Petersburg 198904 (Russian Federation); St.-Petersburg National Research University of Information Technologies, Mechanics and Optics, 49, Kronverkskij, St.-Petersburg 197101 (Russian Federation)

    2014-02-07

    We have fabricated by e-beam lithography periodic arrays of rectangular shaped trenches of different widths into Si substrates. The trenches were filled with iron oxide nanoparticles, 20 nm in diameter, by spin-coating them onto the Si substrate. The trenches have the purpose to assist the self-assembly of the iron oxide nanoparticles. Using x-ray scattering techniques, we have analyzed the structure factor of the trenches before and after filling in order to determine the filling factor. We present a theoretical analysis of the x-ray scattering function within the distorted-wave Born approximation and we present a quantitative comparison between theory and experiment.

  11. Template assisted self-assembly of iron oxide nanoparticles: An x-ray structural analysis

    International Nuclear Information System (INIS)

    Mishra, D.; Zabel, H.; Ulyanov, S. V.; Romanov, V. P.; Uzdin, V. M.

    2014-01-01

    We have fabricated by e-beam lithography periodic arrays of rectangular shaped trenches of different widths into Si substrates. The trenches were filled with iron oxide nanoparticles, 20 nm in diameter, by spin-coating them onto the Si substrate. The trenches have the purpose to assist the self-assembly of the iron oxide nanoparticles. Using x-ray scattering techniques, we have analyzed the structure factor of the trenches before and after filling in order to determine the filling factor. We present a theoretical analysis of the x-ray scattering function within the distorted-wave Born approximation and we present a quantitative comparison between theory and experiment

  12. X-ray absorption study of the electronic structure of Mn-doped amorphous Si

    Energy Technology Data Exchange (ETDEWEB)

    Arenholz, Elke; Zeng, Li; Huegel, A.; Helgren, E.; Hellman, F.; Piamonteze, C.; Arenholz, E.

    2008-03-08

    The electronic structure of Mn in amorphous Si (a-Mn{sub x}Si{sub 1?x}) is studied by X-ray absorption spectroscopy at the Mn L{sub 3,2} edges for x = 0.005-0.18. Except the x = 0.005 sample, which shows a slight signature of Mn{sup 2+} atomic multiplets associated with a local Mn moment, all samples have broad and featureless L{sub 3,2} absorption peaks, corresponding to an itinerant state for all 3d electrons. The broad X-ray absorption spectra exclude the possibility of a localized 3d moment and explain the unexpectedly quenched Mn moment in this magnetically-doped amorphous semiconductor. Such a fully delocalized d state of Mn dopant in Si has not been previously suggested.

  13. Determining biological fine structure by differential absorption of soft x-rays

    International Nuclear Information System (INIS)

    Panessa-Warren, B.J.; Warren, J.B.

    1979-06-01

    The use of soft x-ray contact microscopy in examining histochemically treated human tissue embedded in plastic and exposed as unstained thin sections is demonstrated. When our preliminary data revealed that we could clearly image not only the histochemical reaction product, but the unstained biological fine structure of the surrounding tissues, we decided to test our hypothesis further and see if we could image unstained biological molecular aggregates as well. For this part of the investigation, we chose to examine hydrated proteoglycan aggregates. Proteoglycans are an essential component of the organic matrix of cartilage, and play a primary role in the retention and maintenance of extracellular water. To avoid any artifacts due to the introduction of exogeneous materials, and examine the proteoglycan aggregates in their hydrated, natural configuration, we made contact x-ray images of isolated proteoglycan aggregates in water

  14. X-ray absorption near edge structure (XANES) study of some hydroxamic mixed ligand copper complexes

    International Nuclear Information System (INIS)

    Mishra, A; Parsai, N; Shrivastava, B D; Soni, N

    2012-01-01

    With the advent of modern bright synchrotron radiation sources, X-ray absorption spectra has emerged as a powerful technique for local structure determination, which can be applied to any type of material. The X-ray absorption measurements of four hydroxamic mixed ligand copper complexes have been performed at the recently developed BL-8 Dispersive EXAFS beamline at 2.5 GeV Indus-2 synchrotron at RRCAT, Indore, India. The X-ray absorption near edge structure (XANES) data obtained has been processed using data analysis program Athena. The energies of the K absorption edge, chemical shifts, edge-widths, shifts of the principal absorption maximum in the complexes have been determined. The values of the chemical shift suggest that copper is in oxidation state +2 in all of the complexes. The chemical shift data has been utilized to estimate effective nuclear charge on copper atom. The order of the chemical shifts has been correlated to the relative ionic character of the bonding in these complexes.

  15. Si K EDGE STRUCTURE AND VARIABILITY IN GALACTIC X-RAY BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Norbert S.; Corrales, Lia; Canizares, Claude R. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2016-08-10

    We survey the Si K edge structure in various absorbed Galactic low-mass X-ray binaries (LMXBs) to study states of silicon in the inter- and circum-stellar medium. The bulk of these LMXBs lie toward the Galactic bulge region and all have column densities above 10{sup 22} cm{sup −2}. The observations were performed using the Chandra High Energy Transmission Grating Spectrometer. The Si K edge in all sources appears at an energy value of 1844 ± 0.001 eV. The edge exhibits significant substructure that can be described by a near edge absorption feature at 1849 ± 0.002 eV and a far edge absorption feature at 1865 ± 0.002 eV. Both of these absorption features appear variable with equivalent widths up to several mÅ. We can describe the edge structure using several components: multiple edge functions, near edge absorption excesses from silicates in dust form, signatures from X-ray scattering optical depths, and a variable warm absorber from ionized atomic silicon. The measured optical depths of the edges indicate much higher values than expected from atomic silicon cross sections and interstellar medium abundances, and they appear consistent with predictions from silicate X-ray absorption and scattering. A comparison with models also indicates a preference for larger dust grain sizes. In many cases, we identify Si xiii resonance absorption and determine ionization parameters between log ξ = 1.8 and 2.8 and turbulent velocities between 300 and 1000 km s{sup −1}. This places the warm absorber in close vicinity of the X-ray binaries. In some data, we observe a weak edge at 1.840 keV, potentially from a lesser contribution of neutral atomic silicon.

  16. Racemic crystallography of synthetic protein enantiomers used to determine the X-ray structure of plectasin by direct methods

    Science.gov (United States)

    Mandal, Kalyaneswar; Pentelute, Brad L; Tereshko, Valentina; Thammavongsa, Vilasak; Schneewind, Olaf; Kossiakoff, Anthony A; Kent, Stephen B H

    2009-01-01

    We describe the use of racemic crystallography to determine the X-ray structure of the natural product plectasin, a potent antimicrobial protein recently isolated from fungus. The protein enantiomers l-plectasin and d-plectasin were prepared by total chemical synthesis; interestingly, l-plectasin showed the expected antimicrobial activity, while d-plectasin was devoid of such activity. The mirror image proteins were then used for racemic crystallization. Synchrotron X-ray diffraction data were collected to atomic resolution from a racemic plectasin crystal; the racemate crystallized in the achiral centrosymmetric space group with one l-plectasin molecule and one d-plectasin molecule forming the unit cell. Dimer-like intermolecular interactions between the protein enantiomers were observed, which may account for the observed extremely low solvent content (13%–15%) and more highly ordered nature of the racemic crystals. The structure of the plectasin molecule was well defined for all 40 amino acids and was generally similar to the previously determined NMR structure, suggesting minimal impact of the crystal packing on the plectasin conformation. PMID:19472324

  17. Energetic electron processes fluorescence effects for structured nanoparticles X-ray analysis and nuclear medicine applications

    Energy Technology Data Exchange (ETDEWEB)

    Taborda, A.; Desbrée, A. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM/SDI/LEDI, BP-17, 31, Avenue de la Division Leclerc, 92262 Fontenay-aux-Roses (France); Carvalho, A. [IEQUALTECS, Lda, Rua Dr. Francisco Sá Carneiro, 36, 2500-065 S. Gregório CLD (Portugal); Chaves, P.C. [C" 2TN, Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa, EN10 km 139.7, 2685-066 Bobadela LRS (Portugal); Reis, M.A., E-mail: mareis@ctn.tecnico.ulisboa.pt [IEQUALTECS, Lda, Rua Dr. Francisco Sá Carneiro, 36, 2500-065 S. Gregório CLD (Portugal); C" 2TN, Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa, EN10 km 139.7, 2685-066 Bobadela LRS (Portugal)

    2016-08-15

    Superparamagnetic iron oxide (SPIO) nanoparticles are widely used as contrast agents for nuclear magnetic resonance imaging (MRI), and can be modified for improved imaging or to become tissue-specific or even protein-specific. The knowledge of their detailed elemental composition characterisation and potential use in nuclear medicine applications, is, therefore, an important issue. X-ray fluorescence techniques such as particle induced X-ray emission (PIXE) or X-ray fluorescence spectrometry (XRF), can be used for elemental characterisation even in problematic situations where very little sample volume is available. Still, the fluorescence coefficient of Fe is such that, during the decay of the inner-shell ionised atomic structure, keV Auger electrons are produced in excess to X-rays. Since cross-sections for ionisation induced by keV electrons, for low atomic number atoms, are of the order of 10{sup 3} barn, care should be taken to account for possible fluorescence effects caused by Auger electrons, which may lead to the wrong quantification of elements having atomic number lower than the atomic number of Fe. Furthermore, the same electron processes will occur in iron oxide nanoparticles containing {sup 57}Co, which may be used for nuclear medicine therapy purposes. In the present work, simple approximation algorithms are proposed for the quantitative description of radiative and non-radiative processes associated with Auger electrons cascades. The effects on analytical processes and nuclear medicine applications are quantified for the case of iron oxide nanoparticles, by calculating both electron fluorescence emissions and energy deposition on cell tissues where the nanoparticles may be embedded.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-21

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

  19. Anomalous scattering, transport, and spatial distribution of X-ray fluorescence at the exit of polycapillary structures

    Energy Technology Data Exchange (ETDEWEB)

    Mazuritskiy, M. I., E-mail: mazurmik@gmail.com; Lerer, A. M.; Makhno, P. V. [Southern Federal University (Russian Federation)

    2016-12-15

    The angular distribution of the X-ray intensity at the exit of microchannel plates at grazing incidence of monochromatic radiation on the walls of microcapillaries has been investigated. The angles and energies of the primary radiation quanta at which the synchrotron beam excites X-ray fluorescence propagating inside polycapillary structures have been determined. The angular dependences of the intensity distribution of X-rays transmitted through the microcapillaries have been studied theoretically and experimentally for energies corresponding to the region of anomalous dispersion near the L{sub 2,3} absorption edges of silicon. The propagation of waves in hollow polycapillary waveguides, the excitation of X-ray fluorescence, and the X-ray diffraction at the exit of microchannel plates have been modeled mathematically. The mathematical model takes into account the presence of a transition layer on the microchannel surface.

  20. The effect of SNR structure on non-equilibrium X-ray spectra

    International Nuclear Information System (INIS)

    Hamilton, A.J.S.; Sarazin, C.L.

    1983-01-01

    A technique is presented for characterizing the ionization structure and consequent thermal X-ray emission of a SNR when non-equilibrium ionization effects are important. The technique allows different theoretical SNR models to be compared and contrasted rapidly in advance of detailed numerical computations. In particular it is shown that the spectrum of a Sedov remnant can probably be applied satisfactorily in a variety of SNR structures, including the reverse shock model advocated by Chevalier (1982) for Type I SN, the isothermal similarity solution of Solinger, Rappaport and Buff (1975), and various inhomogenous or 'messy' structures. (Auth.)

  1. Silicon Σ13(5 0 1) grain boundary interface structure determined by bicrystal Bragg rod X-ray scattering

    International Nuclear Information System (INIS)

    Howes, P.B.; Rhead, S.; Roy, M.; Nicklin, C.L.; Rawle, J.L.; Norris, C.A.

    2013-01-01

    The atomic structure of the silicon Σ13(5 0 1) symmetric tilt grain boundary interface has been determined using Bragg rod X-ray scattering. In contrast to conventional structural studies of grain boundary structure using transmission electron microscopy, this approach allows the non-destructive measurement of macroscopic samples. The interface was found to have a single structure that is fully fourfold coordinated. X-ray diffraction data were measured at Beamline I07 at the Diamond Light Source

  2. X-ray structure analyses of biological molecules and particles in Japan. A brief history and future prospect

    International Nuclear Information System (INIS)

    Nakasako, Masayoshi; Yamamoto, Masaki

    2015-01-01

    In Japan, X-ray structure analyses of molecules and particles from biology started in the 1970s. The structure analysis methods have been developed through the innovation of various techniques in advance, and have contributed for understanding the elementary and microscopic processes in life. Here we summarize briefly the history of X-ray structure analyses for structural biology in Japan and think about the prospect. (author)

  3. Providing x-rays

    International Nuclear Information System (INIS)

    Mallozzi, P.J.; Epstein, H.M.

    1985-01-01

    This invention provides an apparatus for providing x-rays to an object that may be in an ordinary environment such as air at approximately atmospheric pressure. The apparatus comprises: means (typically a laser beam) for directing energy onto a target to produce x-rays of a selected spectrum and intensity at the target; a fluid-tight enclosure around the target; means for maintaining the pressure in the first enclosure substantially below atmospheric pressure; a fluid-tight second enclosure adjoining the first enclosure, the common wall portion having an opening large enough to permit x-rays to pass through but small enough to allow the pressure reducing means to evacuate gas from the first enclosure at least as fast as it enters through the opening; the second enclosure filled with a gas that is highly transparent to x-rays; the wall of the second enclosure to which the x-rays travel having a portion that is highly transparent to x-rays (usually a beryllium or plastic foil), so that the object to which the x-rays are to be provided may be located outside the second enclosure and adjacent thereto and thus receive the x-rays substantially unimpeded by air or other intervening matter. The apparatus is particularly suited to obtaining EXAFS (extended x-ray fine structure spectroscopy) data on a material

  4. Synthesis and X-ray diffraction study of new uranyl malonate and oxalate complexes with carbamide

    International Nuclear Information System (INIS)

    Medvedkov, Ya. A.; Serezhkina, L. B.; Grigor’ev, M. S.; Serezhkin, V. N.

    2016-01-01

    Two new malonate-containing uranyl complexes with carbamide of the formulas [UO 2 (C 3 H 2 O 4 )(Urea) 2 ] (I) and [UO 2 (C 3 H 2 O 4 )(Urea) 3 ] (II), where Urea is carbamide, and one uranyl oxalate complex of the formula [UO 2 (C 2 O 4 )(Urea) 3 ] (III) were synthesized, and their crystals were studied by X-ray diffraction. The main structural units in crystals I are the electroneutral chains [UO 2 (C 3 H 2 O 4 )(Urea) 2 ] ∞ belonging to the crystal-chemical group AT 11 M 2 1 (A = UO 2 2+ , T 11 = C 3 H 2 O 4 2- , M 1 = Urea) of uranyl complexes. Crystals II and III are composed of the molecular complexes [UO 2 (L)(Urea) 3 ], where L = C 3 H 2 O 4 2- or C 2 O 4 2- , belonging to the crystal-chemical group AB 01 M 3 1 (A = UO 2 2+ , B 01 = C 3 H 2 O 4 2- or C 2 O 4 2- , M 1 = Urea). The characteristic features of the packing of the uranium-containing complexes are discussed in terms of molecular Voronoi–Dirichlet polyhedra. The effect of the Urea: U ratio on the structure of uranium-containing structural units is considered.

  5. X-ray crystallography and QM/MM investigation on the oligosaccharide synthesis mechanism of rice BGlu1 glycosynthases.

    Science.gov (United States)

    Wang, Jinhu; Pengthaisong, Salila; Cairns, James R Ketudat; Liu, Yongjun

    2013-02-01

    Nucleophile mutants of retaining β-glycosidase can act as glycosynthases to efficiently catalyze the synthesis of oligosaccharides. Previous studies proved that rice BGlu1 mutants E386G, E386S and E386A catalyze the oligosaccharide synthesis with different rates. The E386G mutant gave the fastest transglucosylation rate, which was approximately 3- and 19-fold faster than those of E386S and E386A. To account for the differences of their activities, in this paper, the X-ray crystal structures of BGlu1 mutants E386S and E386A were solved and compared with that of E386G mutant. However, they show quite similar active sites, which implies that their activities cannot be elucidated from the crystal structures alone. Therefore, a combined quantum mechanical/molecular mechanical (QM/MM) calculations were further performed. Our calculations reveal that the catalytic reaction follows a single-step mechanism, i.e., the extraction of proton by the acid/base, E176, and the formation of glycosidic bond are concerted. The energy barriers are calculated to be 19.9, 21.5 and 21.9kcal/mol for the mutants of E386G, E386S and E386A, respectively, which is consistent with the order of their experimental relative activities. But based on the calculated activation energies, 1.1kcal/mol energy difference may translate to nearly 100 fold rate difference. Although the rate limiting step in these mutants has not been established, considering the size of the product and the nature of the active site, it is likely that the product release, rather than chemistry, is rate limiting in these oligosaccharides synthesis catalyzed by BGlu1 mutants. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Small-angle x-ray scattering investigation of the solution structure of troponin C

    International Nuclear Information System (INIS)

    Hubbard, S.R.; Hodgson, K.O.; Doniach, S.

    1988-01-01

    X-ray crystallographic studies of troponin C have revealed a novel protein structure consisting of two globular domains, each containing two Ca 2+ -binding sites, connected via a nine-turn alpha-helix, three turns of which are fully exposed to solvent. Since the crystals were grown at pH approximately 5, it is of interest to determine whether this structure is applicable to the protein in solution under physiological conditions. We have used small-angle x-ray scattering to examine the solution structure of troponin C at pH 6.8 and the effect of Ca 2+ on the structure. The scattering data are consistent with an elongated structure in solution with a radius of gyration of approximately 23.0 A, which is quite comparable to that computed for the crystal structure. The experimental scattering profile and the scattering profile computed from the crystal structure coordinates do, however, exhibit differences at the 40-A level. A weak Ca 2+ -facilitated dimerization of troponin C was observed. The data rule out large Ca 2+ -induced structural changes, indicating rather that the molecule with Ca 2+ bound is only slightly more compact than the Ca 2+ -free molecule

  7. Bioactive Formylated Flavonoids from Eugenia rigida: Isolation, Synthesis, and X-ray Crystallography.

    Science.gov (United States)

    Zaki, Mohamed A; Nanayakkara, N P Dhammika; Hetta, Mona H; Jacob, Melissa R; Khan, Shabana I; Mohammed, Rabab; Ibrahim, Mohamed A; Samoylenko, Volodymyr; Coleman, Christina; Fronczek, Frank R; Ferreira, Daneel; Muhammad, Ilias

    2016-09-23

    Two new flavonoids, rac-6-formyl-5,7-dihydroxyflavanone (1) and 2',6'-dihydroxy-4'-methoxy-3'-methylchalcone (2), together with five known derivatives, rac-8-formyl-5,7-dihydroxyflavanone (3), 4',6'-dihydroxy-2'-methoxy-3'-methyldihydrochalcone (4), rac-7-hydroxy-5-methoxy-6-methylflavanone (5), 3'-formyl-2',4',6'-trihydroxy-5'-methyldihydrochalcone (6), and 3'-formyl-2',4',6'-trihydroxydihydrochalcone (7), were isolated from the leaves of Eugenia rigida. The individual (S)- and (R)-enantiomers of 1 and 3, together with the corresponding formylated flavones 8 (6-formyl-5,7-dihydroxyflavone) and 9 (8-formyl-5,7-dihydroxyflavone), as well as 2',4',6'-trihydroxychalcone (10), 3'-formyl-2',4',6'-trihydroxychalcone (11), and the corresponding 3'-formyl-2',4',6'-trihydroxydihydrochalcone (7) and 2',4',6'-trihydroxydihydrochalcone (12), were synthesized. The structures of the isolated and synthetic compounds were established via NMR, HRESIMS, and electronic circular dichroism data. In addition, the structures of 3, 5, and 8 were confirmed by single-crystal X-ray diffraction crystallography. The isolated and synthetic flavonoids were evaluated for their antimicrobial and cytotoxic activities against a panel of microorganisms and solid tumor cell lines.

  8. Utility Of Stress-Texture Characteristics Of Structural Materials By X-Ray Technique

    Directory of Open Access Journals (Sweden)

    Bonarski J.T.

    2015-09-01

    Full Text Available The article presents the results of residual stress analysis in selected metal-metal joints manufactured by conventional welding and explosive merging. The X-ray diffraction technique applied for advanced stress-texture measurements and data processing revealed directions and values of the principal stresses and their configuration on the surface of the examined structural elements. The obtained stress topography of the joint intersections indicates a possible path of potential cracking formed during the exploitation process and thus it becomes a very useful tool in the diagnostics of structural elements.

  9. X-ray structural investigation into complexes of p-aminobenzoic acid and metals

    International Nuclear Information System (INIS)

    Amiraslanov, I.R.; Musaev, F.N.; Mamedov, Kh.S.

    1982-01-01

    X-ray structural investigation of p-aminobenzoatodiaqua-strontium Sr(H 2 NC 6 H 4 COO) 2 x2H 2 o' was carried out. Crystals were rhombic: a=6.86(1), b=13.39(2), c=18.58(2) A, V=1705 A, Z=4, space group P2 1 2 1 2 1 . The basis of the structure was formed by infinite along the axis a chains of strontium atom octavertices articulated with common oxygen vertices. Sr-O bond lengths were 2.46-2.74 A; the distance between strontium neighbour - ring atom 4.07(1) A. Bond angles were presented

  10. The Crystal Structure of the Malaria Pigment Hemozoin as Elucidated by X-ray Powder Diffraction

    DEFF Research Database (Denmark)

    Straasø, Tine

    survival. Successful inhibition of hemozoin crystallization will lead to parasitic death and thus break the cycle. The aim of this thesis is to elucidate the structure of hemozoin by means of X-ray diffraction techniques. Knowledge of the structure will help facilitate intelligent drug design in the future....... As part of the project an all-in-vacuum powder diffractometer was developed, which provides data with a minimum background level and an improved signal-to-noise ratio. Moreover, the diffractometer is designed with the particular purpose of decreasing the number of parameters to be fitted. Installation...

  11. Structure of ordered polyelectrolyte films from atomic-force microscopy and X-ray reflectivity data

    International Nuclear Information System (INIS)

    Belyaev, V.V.; Tolstikhina, A.L.; Stepina, N.D.; Kayushina, R.L.

    1998-01-01

    The possible application of atomic-force microscopy and X-ray reflectometry methods to structural studies of polyelectrolyte films obtained due to alternating adsorption of oppositely charged polyanion [sodium polysterenesulfonate (PSS)] and polycation [poly(allylamine) hydrochloride (PAA)] layers on solid substrates has been considered. The atomic-force microscopy study has revealed the characteristic features of the surface topography of samples consisting of different numbers of polyelectrolyte layers deposited from solutions characterized by different ionic strength values. It is shown that the shape of the reflectivity curves obtained from thin polyelectrolyte films depends on their surface structure

  12. Time-resolved pump-probe X-ray absorption fine structure spectroscopy of Gaq3

    International Nuclear Information System (INIS)

    Dicke, Benjamin

    2013-01-01

    Gallium(tris-8-hydroxyquinoline) (Gaq 3 ) belongs to a class of metal organic compounds, used as electron transport layer and emissive layer in organic light emitting diodes. Many research activities have concentrated on the optical and electronic properties, especially of the homologue molecule aluminum(tris-8-hydroxyquinoline) (Alq 3 ). Knowledge of the first excited state S 1 structure of these molecules could provide deeper insight into the processes involved into the operation of electronic devices, such as OLEDs and, hence, it could further improve their efficiency and optical properties. Until now the excited state structure could not be determined experimentally. Most of the information about this structure mainly arises from theoretical calculations. X-ray absorption fine structure (XAFS) spectroscopy is a well developed technique to determine both, the electronic and the geometric properties of a sample. The connection of ultrashort pulsed X-ray sources with a pulsed laser system offers the possibility to use XAFS as a tool for studying the transient changes of a sample induced by a laser pulse. In the framework of this thesis a new setup for time-resolved pump-probe X-ray absorption spectroscopy at PETRA III beamline P11 was developed for measuring samples in liquid form. In this setup the sample is pumped into its photo-excited state by a femtosecond laser pump pulse with 343 nm wavelength and after a certain time delay probed by an X-ray probe pulse. In this way the first excited singlet state S 1 of Gaq 3 dissolved in benzyl alcohol was analyzed. A structural model for the excited state structure of the Gaq 3 molecule based on the several times reproduced results of the XAFS experiments is proposed. According to this model it was found that the Ga-N A bond length is elongated, while the Ga-O A bond length is shortened upon photoexcitation. The dynamics of the structural changes were not the focus of this thesis. Nevertheless the excited state lifetime

  13. Structural studies of disordered materials using high-energy x-ray diffraction from ambient to extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kohara, Shinji [Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Itou, Masayoshi [Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Suzuya, Kentaro [Japan Atomic Energy Agency (J-PARC/JAEA), Tokai, Naka, Ibaraki 319-1195 (Japan); Inamura, Yasuhiro [Japan Atomic Energy Agency (J-PARC/JAEA), Tokai, Naka, Ibaraki 319-1195 (Japan); Sakurai, Yoshiharu [Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Ohishi, Yasuo [Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Takata, Masaki [Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan)

    2007-12-19

    High-energy x-rays from a synchrotron radiation source allow us to obtain high-quality diffraction data for disordered materials from ambient to extreme conditions, which is necessary for revealing the detailed structures of glass, liquid and amorphous materials. We introduced high-energy x-ray diffraction beamlines and a dedicated diffractometer for glass, liquid and amorphous materials at SPring-8 and report the recent developments of ancillary equipment. Furthermore, the structures of liquid and amorphous materials determined from the high-energy x-ray diffraction data obtained at SPring-8 are discussed.

  14. Structural investigation of semi-conductor nanostructures by x-ray diffraction

    International Nuclear Information System (INIS)

    Stangl, J.

    2003-01-01

    Full text: Semiconductor nanostructures present a topic of increasing interest due to their potential for new device concepts, as well as from a scientific point of view. In structures with dimensions smaller than the DeBroglie wavelength of electrons or holes, quantum confinement effects determine the electronic and optical properties. For the understanding of such structures, their structural investigation, i.e., the determination of size, shape, chemical composition and strain state is mandatory. X-ray diffraction is a powerful technique for this purpose. In particular, the strain fields within nanostructures as well as in the surrounding matrix can be determined with high precision. Using synchrotron radiation sources, also the distribution of chemical composition within objects with typically several nm height and 10 to 100 nm width can be established. With x-ray diffraction, the non-destructive investigation of uncapped and buried structures is possible. The latter is important, as for applications buried structures are needed, and during capping the structural properties may change considerably. Here, we will focus on so-called self-assembled nanostructures, which form during the deposition of different semiconductors on top of each other. In contrast to structures etched after growth of planar layers, self organized islands or wires are virtually defect-free and hence promising for applications. Different scattering techniques sensitive to shape and/or composition and strain will be discussed. (author)

  15. Electronic structure and X-ray spectroscopic properties of YbNi_2P_2

    International Nuclear Information System (INIS)

    Shcherba, I.D.; Bekenov, L.V.; Antonov, V.N.; Noga, H.; Uskokovic, D.; Zhak, O.; Kovalska, M.V.

    2016-01-01

    Highlights: • We present new experimental and theoretical data for YbNi_2P_2. • The presence of divalent and trivalent Yb ion found in YbNi_2P_2. • The calculation show good agreement with the experimental measurements. - Abstract: X-ray absorption spectrum at the Yb L_3 edge and X-ray emission spectra of Ni and P at the K and L_2_,_3 edges have been studied experimentally and theoretically in the mixed valent compound YbNi_2P_2 with ThCr_2Si_2 type crystal structure. The electronic structure of YbNi_2P_2 is investigated using the fully relativistic Dirac linear muffin-tin orbital (LMTO) band-structure method. The effect of the spin–orbit (SO) interaction and Coulomb repulsion U on the electronic structure of YbNi_2P_2 is examined in the frame of the LSDA + SO + U method. The core-hole effect in the final states as well as the effect of the electric quadrupole E_2 transitions have been investigated. A good agreement between the theory and the experiment was found. Both the trivalent and the divalent Yb ions in YbNi_2P_2 are reflected in the experimentally measured Yb L_3 X-ray absorption spectrum simultaneously. We found that the best agreement between the experimental spectrum and sum of the theoretically calculated Yb"2"+ and Yb"3"+ spectra is achieved with 73% ytterbium ions in 2+ state and 27% ions in 3+ state.

  16. X-ray diffraction using the time structure of the SRS

    International Nuclear Information System (INIS)

    Tanner, B.K.

    1983-01-01

    The subject is discussed under the headings: introduction (advances in the techniques of X-ray topography; comparison with transmission electron microscopy); stroboscopic X-ray topography; stroboscopic X-ray topography of travelling surface acoustic waves; possible general diffraction experiments. (U.K.)

  17. Serial data acquisition for the X-ray plasma diagnostics with selected GEM detector structures

    International Nuclear Information System (INIS)

    Czarski, T.; Chernyshova, M.; Pozniak, K.T.; Kasprowicz, G.; Zabolotny, W.; Kolasinski, P.; Krawczyk, R.; Wojenski, A.; Zienkiewicz, P.

    2015-01-01

    The measurement system based on GEM—Gas Electron Multiplier detector is developed for X-ray diagnostics of magnetic confinement tokamak plasmas. The paper is focused on the measurement subject and describes the fundamental data processing to obtain reliable characteristics (histograms) useful for physicists. The required data processing have two steps: 1—processing in the time domain, i.e. events selections for bunches of coinciding clusters, 2—processing in the planar space domain, i.e. cluster identification for the given detector structure. So, it is the software part of the project between the electronic hardware and physics applications. The whole project is original and it was developed by the paper authors. The previous version based on 1-D GEM detector was applied for the high-resolution X-ray crystal spectrometer KX1 in the JET tokamak. The current version considers 2-D detector structures for the new data acquisition system. The fast and accurate mode of data acquisition implemented in the hardware in real time can be applied for the dynamic plasma diagnostics. Several detector structures with single-pixel sensors and multi-pixel (directional) sensors are considered for two-dimensional X-ray imaging. Final data processing is presented by histograms for selected range of position, time interval and cluster charge values. Exemplary radiation source properties are measured by the basic cumulative characteristics: the cluster position distribution and cluster charge value distribution corresponding to the energy spectra. A shorter version of this contribution is due to be published in PoS at: 1 st EPS conference on Plasma Diagnostics

  18. Small angle neutron and x-ray scattering studies of self-assembled nano structured materials

    International Nuclear Information System (INIS)

    Choi, Sung Min

    2009-01-01

    Full text: Small angle neutron and x-ray scattering are very powerful techniques to investigate nano structured materials. In this presentation, examples of nano structured materials investigated by neutron and x-ray scattering will be presented. Part I: The unique anisotropic physical properties of columnar discotic liquid crystals (DLCs) have attracted considerable interest for their potential applications as electronic devices. For many practical applications, however, it is crucial to obtain uniaxially oriented and highly ordered columnar superstructures of DLC molecules covering macroscopic area. Here, we present a simple and straight-forward approach to fabricate uniaxially oriented and highly ordered columnar superstructures of cobalt octa(n-decylthio) porphyrazine (CoS 1 0), a discotic supra-molecule, in bulk and on substrates [1] over a macroscopic length scale, utilizing an applied magnetic field and the interaction of CoS 1 0 with an OTS-functionalized substrate. The details of the oriented and ordered columnar nano-structures are investigated by SANS and GISAXS. Part II: Self-assembly of one-dimensional (1D) nanoparticles with metallic or semiconducting properties into highly ordered superstructures using various interactions has been of great interest as a route towards materials with new functionalities. Here, we report a new phase diagram of negatively charged 1D nanoparticle (cROD) and cationic liposome (CL) complexes in water which exhibit three different highly ordered phases [2]. Small angle neutron and x-ray scattering measurements show that the cROD-CL complexes exhibit three different highly ordered phases, intercalated lamellar, doubly intercalated lamellar and centered rectangular phases, depending on particle curvature and electrostatic interactions. The new phase diagram can be used to understand and design new highly ordered self-assemblies of 1D nanoparticles in soft matter which provide new functionalities. (author)

  19. Serial data acquisition for the X-ray plasma diagnostics with selected GEM detector structures

    Science.gov (United States)

    Czarski, T.; Chernyshova, M.; Pozniak, K. T.; Kasprowicz, G.; Zabolotny, W.; Kolasinski, P.; Krawczyk, R.; Wojenski, A.; Zienkiewicz, P.

    2015-10-01

    The measurement system based on GEM—Gas Electron Multiplier detector is developed for X-ray diagnostics of magnetic confinement tokamak plasmas. The paper is focused on the measurement subject and describes the fundamental data processing to obtain reliable characteristics (histograms) useful for physicists. The required data processing have two steps: 1—processing in the time domain, i.e. events selections for bunches of coinciding clusters, 2—processing in the planar space domain, i.e. cluster identification for the given detector structure. So, it is the software part of the project between the electronic hardware and physics applications. The whole project is original and it was developed by the paper authors. The previous version based on 1-D GEM detector was applied for the high-resolution X-ray crystal spectrometer KX1 in the JET tokamak. The current version considers 2-D detector structures for the new data acquisition system. The fast and accurate mode of data acquisition implemented in the hardware in real time can be applied for the dynamic plasma diagnostics. Several detector structures with single-pixel sensors and multi-pixel (directional) sensors are considered for two-dimensional X-ray imaging. Final data processing is presented by histograms for selected range of position, time interval and cluster charge values. Exemplary radiation source properties are measured by the basic cumulative characteristics: the cluster position distribution and cluster charge value distribution corresponding to the energy spectra. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

  20. Electronic structure of polycrystalline cadmium dichloride studied by X-ray spectroscopies and ab initio calculations

    International Nuclear Information System (INIS)

    Demchenko, I.N.; Chernyshova, M.; Stolte, W.C.; Speaks, D.T.; Derkachova, A.

    2012-01-01

    The electronic structure of cadmium dichloride has been studied by X-ray absorption near edge structure (XANES) and, for the first time, by resonant inelastic X-ray scattering (RIXS) at the Cl K edge. Good agreement was obtained between the non-resonant X-ray emission (XES) along with XANES experimental spectra and the calculated Cl 3p local partial density of states (DOS). The calculations were performed using the full-potential linearized-augmented-plane-wave with the local orbitals (FP-(L)APW l o) method utilized in the WIEN2k code. It was shown that the position of the RIXS band in CdCl 2 follows a linear dispersion according to the Raman–Stokes law if the excitation energy is tuned below the absorption threshold. The situation changes for core excitation above the photoabsorption threshold where the dispersion relation is split into two branches. The position of the resonant contribution does not depend on the excitation energy, while the excitonic sideband follows the Raman–Stoke law. Combined XANES and RIXS measurements compared to calculated band structure allowed us to determine the direct band gap of CdCl 2 to be at 5.7 ± 0.05 eV. -- Highlights: ► XANES at the K edge of Cl and related emission KV band interpreted within the ab initio DFT formalism. ► Two dominant contributions observed in RIXS data: the resonant and the excitonic ones. ► The dispersion relation below the absorption threshold follows Raman–Stokes law. ► Dispersion above the threshold splits into two qualitatively different relations. ► Overlapping of XAS spectrum with RIXS one makes possible to estimate direct band gap value to be 5.7 eV.

  1. Structural analysis of radiation damage in zircon and thorite: An X-ray absorption spectroscopic study

    International Nuclear Information System (INIS)

    Farges, F.; Calas, G.

    1991-01-01

    Metamictization effects have been investigated in zircon, thorite, uranothorite, and thorogummite using X-ray absorption spectroscopy at Zr-K, Th-L III edges. Extended X-ray absorption fine structure (EXAFS) spectra of metamict samples are characterized by a major contribution due to the O nearest neighbors with some contributions from next-nearest neighbors (Si and Zr in zircon, Si in thorite). In zircon, Zr-O distances decrease by ∼0.1 angstrom while the coordination number of Zr decreases from 8 to 7. In contrast, the eightfold coordination of Th in crystalline thorite is preserved in metamict thorite, Si second neighbors around Zr or Th are generally observed in metamict samples with distances close to those measured in crystalline phases. No other contribution to EXAFS is observed in thorite, but Zr-Zr distances are observed in zircon. They decrease by ca. 0.3 Angstrom as a function of zircon metamictization. Metamictization processes are characterized by a loss of medium range order. There is no evidence for decomposition into crystalline oxides. The structural interpretation of EXAFS data must take into account the creation of O vacancies arising from a displacement or tilting of the SiO 4 tetrahedra during metamictization of zircon-like structures. If the cation can take a lower coordination number (as in the case of Zr), a coordination change allows the local structure to be partly maintained during metamictization. If not, as for Th, the local structure is rapidly destroyed

  2. Analysis of inner structure changes of concretes exposed to high temperatures using micro X-ray computed tomography

    OpenAIRE

    Sitek, L. (Libor); Bodnárová, L.; Souček, K. (Kamil); Staš, L. (Lubomír); Gurková, L. (Lucie)

    2015-01-01

    The X-ray Computed Tomography (X-ray CT) repr esents a progressive non-destructive metho d of analysing the inner structure of materials. The method was used for monitoring changes in inner structure of concrete samples of different composition before and after their exposure to various thermal loads. Eight types of concrete samples were prepared which differed by cement and aggregate types. We intentionally used such composition of concrete mixtures which increased their resist...

  3. Characterization of the electronic structure of C50Cl10 by means of soft x-ray spectroscopies

    International Nuclear Information System (INIS)

    Brena, Barbara; Luo Yi

    2005-01-01

    The electronic structure of the last synthesized fullerene molecule, the C 50 Cl 10 , has been characterized by theoretical simulation of x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and near-edge x-ray-absorption fine structure. All the calculations were performed at the gradient-corrected and hybrid density-functional theory levels. The combination of these techniques provides detailed information about the valence band and the unoccupied molecular orbitals, as well as about the carbon core orbitals

  4. The atomic structure of Fe100-xCux nanoalloys: X-ray absorption analysis

    International Nuclear Information System (INIS)

    Kravtsova, A.N.; Yalovega, G.E.; Soldatov, A.V.; Yan, W.S.; Wei, S.Q.

    2009-01-01

    The local atomic structure of Fe 100-x Cu x nanoalloys (x = 0, 10, 20, 40, 60, 70, 80 and 100%) has been investigated by X-ray absorption near edge structure (XANES) analysis. Local environment around copper and iron atoms in Fe 100-x Cu x has been studied by comparing the experimental XANES with corresponding theoretical spectra calculated for several structural models. It has been established that the most probable structure of the Fe 100-x Cu x nanoalloys for a low concentration of copper (x = 10-20%) is a homogenous bcc structure, for a high copper concentration (x = 60-80%)-a homogenous fcc structure, while at an intermediate copper concentration (about 40%) the nanoalloys have an inhomogeneous structure consisting of clusters of fcc solid solution (90%) and of clusters of bcc solid solution (10%)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-20

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

  6. Raphide crystal structure in agave tequilana determined by x-ray originating from synchrotron radiation

    International Nuclear Information System (INIS)

    Tadokoro, Makoto; Ozawa, Yoshiki; Mitsumi, Minoru; Toriumi, Kohshiro; Ogura, Tetsuya

    2005-01-01

    The first single crystal structure of small natural raphides in an agave plant is completely determined using an intense X-ray originating from a synchrotron radiation. The SEM image shows that the tip of the crystal is approximately hundreds of nanometer in width sharply grow to stick to the tissue of herbivorous vermin. Furthermore, the crystal develops cracks that propagate at an inclination of approximately 45deg towards the direction of crystal growth such that the crystal easily splits into small pieces in the tissue. (author)

  7. Diffuse x-ray scattering study of interfacial structure of self-assembled conjugated polymers

    International Nuclear Information System (INIS)

    Wang Jun; Park, Y.J.; Lee, K.-B.; Hong, H.; Davidov, D.

    2002-01-01

    The interfacial structures of self-assembled heterostructures through alternate deposition of conjugated and nonconjugated polymers were studied by x-ray reflectivity and nonspecular scattering. We found that the interfacial width including the effects of both interdiffusion and interfacial roughness (correlated) was mainly contributed by the latter one. The self-assembled deposition induced very small interdiffusion between layers. The lateral correlation length ξ parallel grew as a function of deposition time (or film thickness) described by a power law ξ parallel ∝t β/H and was also observed from the off-specular scattering

  8. Malnutrition and myelin structure: an X-ray scattering study of rat sciatic and optic nerves

    International Nuclear Information System (INIS)

    Vargas, V.; Vargas, R.; Marquez, G.; Vonasek, E.; Mateu, L.; Luzzati, V.; Borges, J.

    2000-01-01

    Taking advantage of the fast and accurate X-ray scattering techniques recently developed in our laboratory, we tackled the study of the structural alterations induced in myelin by malnutrition. Our work was performed on sciatic and optic nerves dissected from rats fed with either a normal or a low-protein caloric diet, as a function of age (from birth to 60 days). By way of electrophysiological controls we also measured (on the sciatic nerves) the height and velocity of the compound action potential. Malnutrition was found to decrease the amount of myelin and to impair the packing order of the membranes in the sheaths. (orig.)

  9. Determination of Ni(II) crystal structure by powder x-ray diffraction ...

    African Journals Online (AJOL)

    X-ray powder diffraction pattern was used to determine the length of the unit cell, “a”, the lattice structure type, and the number of atoms per unit cell of Ni(II) crystal. The “a” value was determined to be 23.66 ± 0.005 Å, particle size of 34.87 nm, volume 13.24 Å and Strain value ε = 9.8 x 10-3. The cell search on PXRD patterns ...

  10. A method for assessing the structural shielding in diagnostic x-ray facilities

    International Nuclear Information System (INIS)

    Almeida, F.; Martinez de la Fuente, O.; Perez, C.

    1992-01-01

    The design of each X-Ray medical facility involves, in order to guarantee the optimun levels of Radiologic safety for everybody who could be exposed during the performance of the examinations the need of assessing the required shieldings for the room which contains the emiter tubes. In such sense, this paper gives a number of criteria to calculate the structural requirements for the diverse configurations which exist in Health Centres using the method proposed by NCRP in its Report 49 as a reference. (author)

  11. Extended X-ray absorption fine structure (EXAFS) studies of supported catalysts

    International Nuclear Information System (INIS)

    Joyner, R.W.

    1979-01-01

    Since the rebirth of interest in extended X-ray absorption fine structure there have been several studies of systems of catalytic interest. This note is a preliminary account of an investigation of supported platinum catalysts and NiO/Al 2 O 3 catalysts. Experiments were performed on pressed disc samples at the DESY synchrotron, Hamburg, using the EXAFS spectrometer. The synchrotron operated at 7 GeV energy with a circulating current of approximately 4 mA; spectrum accumulation time was typically 45 minutes. (author)

  12. X-ray diffraction studies of the structure and orientations of thiophene and fluorenone based molecule

    International Nuclear Information System (INIS)

    Porzio, William; Pasini, Mariacecilia; Destri, Silvia; Giovanella, Umberto; Fontaine, Philippe

    2006-01-01

    The crystal structure of a conjugated molecule containing thiophene and fluorenone residues has been determined from powder X-ray diffraction (XRD). Thin films ( -5 Pa) onto oxidized silicon substrates, are oriented along with different crystallographic directions. A comparison of XRD in both Grazing Incidence and Bragg-Brentano geometries allowed to perform a quantitative analysis of the various orientations. This approach is generally applicable in the case of multi-oriented films. The results fully account for the poor performance of this molecule in p-type field effect transistor devices

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    Graphene oxide (GO) and reduced graphene oxide (rGO) are important materials in a wide range of fields. The modified Hummers methods, for synthesizing GO, and subsequent thermal reduction to rGO, are often employed for production of rGO. However, the mechanism behinds these syntheses methods are still unclear. We present an in situ X-ray diffraction study of the synthesis of GO and thermal reduction of GO. The X-ray diffraction revealed that the Hummers method includes an intercalation state and finally formation of additional crystalline material. The formation of GO is observed during both the intercalation and the crystallization stage. During thermal reduction of GO three stages were observed: GO, a disordered stage, and the rGO stage. The appearance of these stages depends on the heating ramp. The aim of this study is to provide deeper insight into the chemical and physical processes during the syntheses. - Graphical abstract: In situ X-ray diffraction results for of the modified Hummers synthesis and the thermal reduction of graphene oxide, revealing three stages for both syntheses as well as new GO diffraction peaks and unidentified crystalline material for the Hummers synthesis and a disordered stage for the thermal reduction of graphene oxide. Display Omitted - Highlights: • Hummers synthesis consists of three stages: dissolution, intercalation and crystal. • GO is produced early on during the synthesis and display new diffraction peaks. • An unidentified triclinic phase is observed for the Hummers synthesis. • Thermal reduction of GO display three stages: GO, a disordered stage and rGO. • In situ XRD indicate reformation of rGO even for fast heated thermal reduction.

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

    Energy Technology Data Exchange (ETDEWEB)

    Storm, Mie Møller, E-mail: mmst@dtu.dk; Johnsen, Rune E.; Norby, Poul

    2016-08-15

    Graphene oxide (GO) and reduced graphene oxide (rGO) are important materials in a wide range of fields. The modified Hummers methods, for synthesizing GO, and subsequent thermal reduction to rGO, are often employed for production of rGO. However, the mechanism behinds these syntheses methods are still unclear. We present an in situ X-ray diffraction study of the synthesis of GO and thermal reduction of GO. The X-ray diffraction revealed that the Hummers method includes an intercalation state and finally formation of additional crystalline material. The formation of GO is observed during both the intercalation and the crystallization stage. During thermal reduction of GO three stages were observed: GO, a disordered stage, and the rGO stage. The appearance of these stages depends on the heating ramp. The aim of this study is to provide deeper insight into the chemical and physical processes during the syntheses. - Graphical abstract: In situ X-ray diffraction results for of the modified Hummers synthesis and the thermal reduction of graphene oxide, revealing three stages for both syntheses as well as new GO diffraction peaks and unidentified crystalline material for the Hummers synthesis and a disordered stage for the thermal reduction of graphene oxide. Display Omitted - Highlights: • Hummers synthesis consists of three stages: dissolution, intercalation and crystal. • GO is produced early on during the synthesis and display new diffraction peaks. • An unidentified triclinic phase is observed for the Hummers synthesis. • Thermal reduction of GO display three stages: GO, a disordered stage and rGO. • In situ XRD indicate reformation of rGO even for fast heated thermal reduction.

  15. Near-Edge X-ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

    Energy Technology Data Exchange (ETDEWEB)

    Willey, T M; Fabbri, J; Lee, J I; Schreiner, P; Fokin, A A; Tkachenko, B A; Fokina, N A; Dahl, J; Carlson, B; Vance, A L; Yang, W; Terminello, L J; van Buuren, T; Melosh, N

    2007-11-27

    Diamondoids, hydrocarbon molecules with cubic-diamond-cage structures, have unique properties with potential value for nanotechnology. The availability and ability to selectively functionalize this special class of nanodiamond materials opens new possibilities for surface-modification, for high-efficiency field emitters in molecular electronics, as seed crystals for diamond growth, or as robust mechanical coatings. The properties of self-assembled monolayers (SAMs) of diamondoids are thus of fundamental interest for a variety of emerging applications. This paper presents the effects of thiol substitution position and polymantane order on diamondoid SAMs on gold using near-edge X-ray absorption fine structure spectroscopy (NEXAFS) and X-ray photoelectron spectroscopy (XPS). A framework to determine both molecular tilt and twist through NEXAFS is presented and reveals highly ordered diamondoid SAMs, with the molecular orientation controlled by the thiol location. C 1s and S 2p binding energies are lower in adamantane thiol than alkane thiols on gold by 0.67 {+-} 0.05 eV and 0.16 {+-} 0.04 eV respectively. These binding energies vary with diamondoid monolayer structure and thiol substitution position, consistent with different amounts of steric strain and electronic interaction with the substrate. This work demonstrates control over the assembly, in particular the orientational and electronic structure, providing a flexible design of surface properties with this exciting new class of diamond clusters.

  16. Non-destructive X-ray examination of weft knitted wire structures

    Science.gov (United States)

    Obermann, M.; Ellouz, M.; Aumann, S.; Martens, Y.; Bartelt, P.; Klöcker, M.; Kordisch, T.; Ehrmann, A.; Weber, M. O.

    2016-07-01

    Conductive yarns or wires are often integrated in smart textiles to enable data or energy transmission. In woven fabrics, these conductive parts are fixed at defined positions and thus protected from external loads. Knitted fabrics, however, have relatively loose structures, resulting in higher impacts of possible mechanical forces on the individual yarns. Hence, metallic wires with smaller diameters in particular are prone to break when integrated in knitted fabrics. In a recent project, wires of various materials including copper, silver and nickel with diameters varying between 0.05 mm and 0.23 mm were knitted in combination with textile yarns. Hand flat knitting machines of appropriate gauges were used to produce different structures. On these samples, non-destructive examinations, using an industrial X-ray system Seifert x|cube (225 kV) equipped with a minifocus X-ray tube, were carried out, directly after knitting as well as after different mechanical treatments (tensile, burst, and washing tests). In this way, structural changes of the stitch geometry could be visualized before failure. In this paper, the loop geometries in the knitted fabrics are depicted depending on knitted structures, wire properties and the applied mechanical load. Consequently, it is shown which metallic wires and yarns are most suitable to be integrated into knitted smart textiles.

  17. Synthesis and X-ray diffraction study of new uranyl malonate and oxalate complexes with carbamide

    Energy Technology Data Exchange (ETDEWEB)

    Medvedkov, Ya. A.; Serezhkina, L. B., E-mail: Lserezh@samsu.ru [Samara State University (Russian Federation); Grigor’ev, M. S. [Russian Academy of Sciences, Frumkin Institute of Physical Chemistry and Electrochemistry (Russian Federation); Serezhkin, V. N. [Samara State University (Russian Federation)

    2016-05-15

    Two new malonate-containing uranyl complexes with carbamide of the formulas [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Urea){sub 2}] (I) and [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Urea){sub 3}] (II), where Urea is carbamide, and one uranyl oxalate complex of the formula [UO{sub 2}(C{sub 2}O{sub 4})(Urea){sub 3}] (III) were synthesized, and their crystals were studied by X-ray diffraction. The main structural units in crystals I are the electroneutral chains [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Urea){sub 2}]{sub ∞} belonging to the crystal-chemical group AT{sup 11}M{sub 2}{sup 1} (A = UO{sub 2}{sup 2+}, T{sup 11} = C{sub 3}H{sub 2}O{sub 4}{sup 2-}, M{sup 1} = Urea) of uranyl complexes. Crystals II and III are composed of the molecular complexes [UO{sub 2}(L)(Urea){sub 3}], where L = C{sub 3}H{sub 2}O{sub 4}{sup 2-} or C{sub 2}O{sub 4}{sup 2-}, belonging to the crystal-chemical group AB{sup 01}M{sub 3}{sup 1} (A = UO{sub 2}{sup 2+}, B{sup 01} = C{sub 3}H{sub 2}O{sub 4}{sup 2-} or C{sub 2}O{sub 4}{sup 2-}, M{sup 1} = Urea). The characteristic features of the packing of the uranium-containing complexes are discussed in terms of molecular Voronoi–Dirichlet polyhedra. The effect of the Urea: U ratio on the structure of uranium-containing structural units is considered.

  18. Soft x-ray absorption spectroscopy on Co doped ZnO: structural distortions and electronic structure

    International Nuclear Information System (INIS)

    Kowalik, I A; Guziewicz, E; Godlewski, M; Arvanitis, D

    2016-01-01

    We present soft x-ray absorption spectra from a series of Co doped ZnO films. We discuss systematic variations of the Co L-edge white line intensity and multiplet features for this series of samples. We document sizeable differences in the electronic state of the Co ionic cores, as well as in the local environment of the host lattice atoms, characterised by means of x-ray absorption spectra at the O K-edge and Zn L-edges. Model calculations allow to correlate the observed effects to small structural distortions of the ZnO lattice. (paper)

  19. The aquatic hyphomycete Heliscus lugdunensis protects its hyphae tip cells from cadmium: A micro X-ray fluorescence and X-ray absorption near edge structure spectroscopy study

    Science.gov (United States)

    Isaure, Marie-Pierre; Leyh, Benjamin; Salomé, Murielle; Krauss, Gerd-Joachim; Schaumlöffel, Dirk; Dobritzsch, Dirk

    2017-11-01

    Aquatic fungi can be used to evaluate the functioning of natural ecosystems. Heliscus lugdunensis is an early colonizer of allochthone leafs. Since this aquatic hyphomycete is able to develop in metal contaminated habitats and tolerates cadmium, it appears to be a good candidate to investigate adaptation to metal pollution. This study aimed at examining the sequestration of Cd in the hyphae of H. lugdunensis, and particularly the role of the tip cells. For that, H. lugdunensis growth was evaluated under various Cd concentrations, and a combination of synchrotron micro X-ray fluorescence and X-ray absorption near edge structure spectroscopy was carried out to determine the compartments of Cd accumulation and the Cd chemical species, respectively. Results showed that the hyphal tip cells were depleted in Cd, and that the metal was stored in older cells. Cd was mainly associated with sulfur ligands and to a lesser extent bound to phosphates and carboxyl/hydroxyl groups from cell wall and/or organic acids. Finally, the aquatic fungus was able to maintain the tip cell as a functional system, thus allowing the colonization of contaminated environments.

  20. 5 K extended X-ray absorption fine structure and 40 K 10-s resolved extended X-ray absorption fine structure studies of photolyzed carboxymyoglobin

    International Nuclear Information System (INIS)

    Teng, T.Y.; Huang, H.W.; Olah, G.A.

    1987-01-01

    A previous extended X-ray absorption fine structure (EXAFS) study of photolyzed carboxymyoglobin (MbCO) has provoked much discussion on the heme structure of the photoproduct (Mb*CO). The EXAFS interpretation that the Fe-Co distance increases by no more than 0.05 A following photodissociation has been regarded as inconsistent with optical, infrared, and magnetic susceptibility studies. The present experiment was performed with well-characterized dry film samples in which MbCO molecules were embedded in a poly(vinyl alcohol) matrix. The sample had a high protein concentration (12 mM) to yield adequate EXAFS signals but was very thin (40 μm) so that complete photolysis could be easily achieved by a single flash from a xenon lamp. Although the electronic state of Mb*CO resembles that of deoxymyoglobin (deoxy-Mb), direct comparison of EXAFS spectra indicates that structurally Mb*CO is much closer to MbCO than to deoxy-Mb. Our EXAFS analysis shows that photolysis of MbCO at 5 K leads to a stable intermediate state in which CO has moved away from iron by a distance of 0.27-0.45 A, but the 5-coordinate heme structure is strained in a form similar to that of MbCO; the resolution of the CO position depends on the structure parameters of MbCO which we use as a reference for the analysis of Mb*CO. At 40 K, from 1 to 10 s after photolysis, 42% of the photoproduct has relaxed to the ground state, and the EXAFS spectrum of the remaining photoproduct is indistinguishable from that of the 5 K photoproduct

  1. Perlite-SO3H nanoparticles as an efficient and reusable catalyst for one-pot three-component synthesis of 1,2-dihydro-1-aryl-naphtho[1,2-e][1,3]oxazine-3-one derivatives under both microwave-assisted and thermal solvent-free conditions: Single crystal X-ray structure analysis and theoretical study

    Directory of Open Access Journals (Sweden)

    Ali Ramazani

    2016-01-01

    Full Text Available A general synthetic route for the synthesis of 1,2-dihydro-1-aryl-naphtho[1,2-e][1,3]oxazine-3-one derivatives has been developed using perlite-SO3H nanoparticles as efficient catalyst under both microwave-assisted and thermal solvent-free conditions. The combination of 2-naphthol, aldehyde and urea enabled the synthesis of 1,2-dihydro-1-aryl-naphtho[1,2-e][1,3]oxazine-3-one derivatives in the presence of perlite-SO3H nanoparticles in good to excellent yields. This method provides several advantages like simple work-up, environmentally benign, and shorter reaction times along with high yields. In order to explore the recyclability of the catalyst, the perlite-SO3H nanoparticles in solvent-free conditions were used as catalyst for the same reaction repeatedly and the change in their catalytic activity was studied. It was found that perlite-SO3H nanoparticles could be reused for four cycles with negligible loss of their activity. Single crystal X-ray structure analysis and theoretical studies also were investigated for 4i product. The electronic properties of the compound have been analyzed using DFT calculations (B3LYP/6-311+G*. The FMO analysis suggests that charge transfer takes place within the molecule and the HOMO is localized mainly on naphthalene and oxazinone rings whereas the LUMO resides on the naphthalene ring.

  2. CheShift-2 resolves a local inconsistency between two X-ray crystal structures

    International Nuclear Information System (INIS)

    Vila, Jorge A.; Sue, Shih-Che; Fraser, James S.; Scheraga, Harold A.; Dyson, H. Jane

    2012-01-01

    Since chemical shifts provide important and relatively accessible information about protein structure in solution, a Web server, CheShift-2, was developed for structure interrogation, based on a quantum mechanics database of 13 C α chemical shifts. We report the application of CheShift-2 to a local inconsistency between two X-ray crystal structures (PDB IDs 1IKN and 1NFI) of the complex between the p65/p50 heterodimer of NFκB and its inhibitor IκBα. The availability of NMR resonance assignments that included the region of the inconsistency provided an opportunity for independent validation of the CheShift-2 server. Application of the server showed that the 13 C α chemical shifts measured for the Gly270-Pro281 sequence close to the C-terminus of IκBα were unequivocally consistent with the backbone structure modeled in the 1IKN structure, and were inconsistent with the 1NFI structure. Previous NOE measurements had demonstrated that the position of a tryptophan ring in the region immediately N-terminal in this region was not consistent with either structure. Subsequent recalculation of the local structure in this region, based on the electron density of the deposited structure factors for 1IKN, confirmed that the local backbone structure was best modeled by 1IKN, but that the rotamer of Trp258 is consistent with the 1NFI structure, including the presence of a hydrogen bond between the ring NεH of Trp258 and the backbone carbonyl group of Gln278. The consensus between all of these measures suggests that the CheShift-2 server operates well under circumstances in which backbone chemical shifts are available but where local plasticity may render X-ray structural data ambiguous.

  3. Particle-scale structure in frozen colloidal suspensions from small-angle x-ray scattering

    KAUST Repository

    Spannuth, Melissa; Mochrie, S. G. J.; Peppin, S. S. L.; Wettlaufer, J. S.

    2011-01-01

    During directional solidification of the solvent in a colloidal suspension, the colloidal particles segregate from the growing solid, forming high-particle-density regions with structure on a hierarchy of length scales ranging from that of the particle-scale packing to the large-scale spacing between these regions. Previous work has concentrated mostly on the medium- to large-length scale structure, as it is the most accessible and thought to be more technologically relevant. However, the packing of the colloids at the particle scale is an important component not only in theoretical descriptions of the segregation process, but also to the utility of freeze-cast materials for new applications. Here we present the results of experiments in which we investigated this structure across a wide range of length scales using a combination of small-angle x-ray scattering and direct optical imaging. As expected, during freezing the particles were concentrated into regions between ice dendrites forming a microscopic pattern of high- and low-particle-density regions. X-ray scattering indicates that the particles in the high-density regions were so closely packed as to be touching. However, the arrangement of the particles does not conform to that predicted by standard interparticle pair potentials, suggesting that the particle packing induced by freezing differs from that formed during equilibrium densification processes. © 2011 American Physical Society.

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

    Science.gov (United States)

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

    2014-09-01

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

  5. Particle-scale structure in frozen colloidal suspensions from small-angle x-ray scattering

    KAUST Repository

    Spannuth, Melissa

    2011-02-01

    During directional solidification of the solvent in a colloidal suspension, the colloidal particles segregate from the growing solid, forming high-particle-density regions with structure on a hierarchy of length scales ranging from that of the particle-scale packing to the large-scale spacing between these regions. Previous work has concentrated mostly on the medium- to large-length scale structure, as it is the most accessible and thought to be more technologically relevant. However, the packing of the colloids at the particle scale is an important component not only in theoretical descriptions of the segregation process, but also to the utility of freeze-cast materials for new applications. Here we present the results of experiments in which we investigated this structure across a wide range of length scales using a combination of small-angle x-ray scattering and direct optical imaging. As expected, during freezing the particles were concentrated into regions between ice dendrites forming a microscopic pattern of high- and low-particle-density regions. X-ray scattering indicates that the particles in the high-density regions were so closely packed as to be touching. However, the arrangement of the particles does not conform to that predicted by standard interparticle pair potentials, suggesting that the particle packing induced by freezing differs from that formed during equilibrium densification processes. © 2011 American Physical Society.

  6. Characterization of the Electronic Structure of Silicon Nanoparticles Using X-ray Absorption and Emission

    Energy Technology Data Exchange (ETDEWEB)

    Vaverka, April Susan Montoya [Univ.of California, Davis, CA (United States)

    2008-01-01

    Resolving open questions regarding transport in nanostructures can have a huge impact on a broad range of future technologies such as light harvesting for energy. Silicon has potential to be used in many of these applications. Understanding how the band edges of nanostructures move as a function of size, surface termination and assembly is of fundamental importance in understanding the transport properties of these materials. In this thesis work I have investigated the change in the electronic structure of silicon nanoparticle assemblies as the surface termination is changed. Nanoparticles are synthesized using a thermal evaporation technique and sizes are determined using atomic force microscopy (AFM). By passivating the particles with molecules containing alcohol groups we are able to modify the size dependent band edge shifts. Both the valence and conduction bands are measured using synchrotron based x-ray absorption spectroscopy (XAS) and soft x-ray fluorescence (SXF) techniques. Particles synthesized via recrystallization of amorphous silicon/SiO2 multilayers of thicknesses below 10 nm are also investigated using the synchrotron techniques. These samples also show quantum confinement effects but the electronic structure is different from those synthesized via evaporation methods. The total bandgap is determined for all samples measured. The origins of these differences in the electronic structures are discussed.

  7. Time-Resolved Soft X-ray Diffraction Reveals Transient Structural Distortions of Ternary Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Klaus Mann

    2009-11-01

    Full Text Available Home-based soft X-ray time-resolved scattering experiments with nanosecond time resolution (10 ns and nanometer spatial resolution were carried out at a table top soft X-ray plasma source (2.2–5.2 nm. The investigated system was the lyotropic liquid crystal C16E7/paraffin/glycerol/formamide/IR 5. Usually, major changes in physical, chemical, and/or optical properties of the sample occur as a result of structural changes and shrinking morphology. Here, these effects occur as a consequence of the energy absorption in the sample upon optical laser excitation in the IR regime. The liquid crystal shows changes in the structural response within few hundred nanoseconds showing a time decay of 182 ns. A decrease of the Bragg peak diffracted intensity of 30% and a coherent macroscopic movement of the Bragg reflection are found as a response to the optical pump. The Bragg reflection movement is established to be isotropic and diffusion controlled (1 μs. Structural processes are analyzed in the Patterson analysis framework of the time-varying diffraction peaks revealing that the inter-lamellar distance increases by 2.7 Å resulting in an elongation of the coherently expanding lamella crystallite. The present studies emphasize the possibility of applying TR-SXRD techniques for studying the mechanical dynamics of nanosystems.

  8. X-ray crystallography

    Science.gov (United States)

    2001-01-01

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

  9. Determination of line profiles on nano-structured surfaces using EUV and x-ray scattering

    Science.gov (United States)

    Soltwisch, Victor; Wernecke, Jan; Haase, Anton; Probst, Jürgen; Schoengen, Max; Krumrey, Michael; Scholze, Frank; Pomplun, Jan; Burger, Sven

    2014-09-01

    Non-imaging techniques like X-ray scattering are supposed to play an important role in the further development of CD metrology for the semiconductor industry. Grazing Incidence Small Angle X-ray Scattering (GISAXS) provides directly assessable information on structure roughness and long-range periodic perturbations. The disadvantage of the method is the large footprint of the X-ray beam on the sample due to the extremely shallow angle of incidence. This can be overcome by using wavelengths in the extreme ultraviolet (EUV) spectral range, EUV small angle scattering (EUVSAS), which allows for much steeper angles of incidence but preserves the range of momentum transfer that can be observed. Generally, the potentially higher momentum transfer at shorter wavelengths is counterbalanced by decreasing diffraction efficiency. This results in a practical limit of about 10 nm pitch for which it is possible to observe at least the +/- 1st diffraction orders with reasonable efficiency. At the Physikalisch-Technische Bundesanstalt (PTB), the available photon energy range extends from 50 eV up to 10 keV at two adjacent beamlines. PTB commissioned a new versatile Ellipso-Scatterometer which is capable of measuring 6" square substrates in a clean, hydrocarbon-free environment with full flexibility regarding the direction of the incident light polarization. The reconstruction of line profiles using a geometrical model with six free parameters, based on a finite element method (FEM) Maxwell solver and a particle swarm based least-squares optimization yielded consistent results for EUV-SAS and GISAXS. In this contribution we present scatterometry data for line gratings and consistent reconstruction results of the line geometry for EUV-SAS and GISAXS.

  10. Protein NMR Structures Refined with Rosetta Have Higher Accuracy Relative to Corresponding X-ray Crystal Structures

    Science.gov (United States)

    2014-01-01

    We have found that refinement of protein NMR structures using Rosetta with experimental NMR restraints yields more accurate protein NMR structures than those that have been deposited in the PDB using standard refinement protocols. Using 40 pairs of NMR and X-ray crystal structures determined by the Northeast Structural Genomics Consortium, for proteins ranging in size from 5–22 kDa, restrained Rosetta refined structures fit better to the raw experimental data, are in better agreement with their X-ray counterparts, and have better phasing power compared to conventionally determined NMR structures. For 37 proteins for which NMR ensembles were available and which had similar structures in solution and in the crystal, all of the restrained Rosetta refined NMR structures were sufficiently accurate to be used for solving the corresponding X-ray crystal structures by molecular replacement. The protocol for restrained refinement of protein NMR structures was also compared with restrained CS-Rosetta calculations. For proteins smaller than 10 kDa, restrained CS-Rosetta, starting from extended conformations, provides slightly more accurate structures, while for proteins in the size range of 10–25 kDa the less CPU intensive restrained Rosetta refinement protocols provided equally or more accurate structures. The restrained Rosetta protocols described here can improve the accuracy of protein NMR structures and should find broad and general for studies of protein structure and function. PMID:24392845

  11. X-ray absorption spectroscopy investigation of structurally modified lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vitova, Tonya

    2008-02-15

    The type and concentration of impurity centers in different valence states are crucial for tuning the photorefractive properties of doped Lithium Niobate (LN) crystals. X-ray Absorption Spectroscopy (XAS) is an appropriate tool for studying the local structure of impurity centers. XAS combined with absorption in UV/VIS/IR and High Resolution X-ray Emission Spectroscopy (HRXES) provide information about the valence state of the dopant ions in as-grown, reduced or oxidized doped LN crystals. Cu (Cu{sup 1+} and Cu{sup 2+}) and Fe (Fe{sup 2+} and Fe{sup 3+}) atoms are found in two different valence states, whereas there are indications for a third Mn valency, in addition to Mn{sup 2+} and Mn{sup 3+} in manganese-doped LN crystals. One of the charge compensation mechanisms during reduction of copper- doped LN crystals is outgassing of oxygen atoms. Cu ions in the reduced crystals have at least two different site symmetries: twofold (Cu{sup 1+}) and sixfold (Cu{sup 2+}) coordinated by O atoms. Fe and Mn atoms are coordinated by six O atoms. Cu and Fe ions are found to occupy only Li sites, whereas Mn ions are also incorporated into Li and Nb sites. The refractive index change in LN crystals irradiated with {sup 3}He{sup 2+} ions is caused by structurally disordered centers, where Nb atoms are displaced from normal crystallographic sites and Li or/and O vacancies are present. (orig.)

  12. X-ray absorption spectroscopy investigation of structurally modified lithium niobate crystals

    International Nuclear Information System (INIS)

    Vitova, Tonya

    2008-02-01

    The type and concentration of impurity centers in different valence states are crucial for tuning the photorefractive properties of doped Lithium Niobate (LN) crystals. X-ray Absorption Spectroscopy (XAS) is an appropriate tool for studying the local structure of impurity centers. XAS combined with absorption in UV/VIS/IR and High Resolution X-ray Emission Spectroscopy (HRXES) provide information about the valence state of the dopant ions in as-grown, reduced or oxidized doped LN crystals. Cu (Cu 1+ and Cu 2+ ) and Fe (Fe 2+ and Fe 3+ ) atoms are found in two different valence states, whereas there are indications for a third Mn valency, in addition to Mn 2+ and Mn 3+ in manganese-doped LN crystals. One of the charge compensation mechanisms during reduction of copper- doped LN crystals is outgassing of oxygen atoms. Cu ions in the reduced crystals have at least two different site symmetries: twofold (Cu 1+ ) and sixfold (Cu 2+ ) coordinated by O atoms. Fe and Mn atoms are coordinated by six O atoms. Cu and Fe ions are found to occupy only Li sites, whereas Mn ions are also incorporated into Li and Nb sites. The refractive index change in LN crystals irradiated with 3 He 2+ ions is caused by structurally disordered centers, where Nb atoms are displaced from normal crystallographic sites and Li or/and O vacancies are present. (orig.)

  13. Evaluation of osteoporotic bone structure through synchrotron radiation X-ray microfluorescence images

    Energy Technology Data Exchange (ETDEWEB)

    Lima, I. [Nuclear Engineering Program/COPPE/UFRJ, P.O. Box 68509, Av. Horacio Macedo 2030, Sala I-133, Cidade Universitaria, 21941-914 Rio de Janeiro, RJ (Brazil)], E-mail: inaya@lin.ufrj.br; Anjos, M.J. [Nuclear Engineering Program/COPPE/UFRJ, P.O. Box 68509, Av. Horacio Macedo 2030, Sala I-133, Cidade Universitaria, 21941-914 Rio de Janeiro, RJ (Brazil); Physics Institute, UERJ (Brazil); Farias, M.L.F. [University Hospital, UFRJ (Brazil); Pantaleao, T.U.; Correa da Costa, V.M. [Biophysics Institute, UFRJ (Brazil); Lopes, R.T. [Nuclear Engineering Program/COPPE/UFRJ, P.O. Box 68509, Av. Horacio Macedo 2030, Sala I-133, Cidade Universitaria, 21941-914 Rio de Janeiro, RJ (Brazil)

    2008-12-15

    The abnormal accumulation or deficiency of trace elements may theoretically impair the formation of bone and contribute to osteoporosis. In this context, the knowledge of major and trace elements is very important in order to clarify many issues regarding diseases of the bone, such as osteoporosis, that remain unresolved. Several kinds of imaging techniques can be useful to access morphology and the minerals present in osteoporotic bones. In this work, synchrotron radiation X-ray microfluorescence was used as an X-ray imaging technique to investigate bone structures. Therefore, this research aims to improve the knowledge about some aspects of bone quality. The measurements were carried out at the Brazilian Synchrotron Laboratory Light Laboratory, in Brazil. A white beam with an energy range of 4-23 keV, a 45 deg./45 deg. geometry and a capillary optics were used. It was demonstrated that bone quality can and must be evaluated not only by considering the architecture of bones but also by taking into account the concentration and the distribution of minerals. Our results showed that the elemental distributions in bone zones on a micron scale were very helpful to understand functions in those structures.

  14. Electronic structure of human hemoglobin: ultrasoft X-ray emission study

    International Nuclear Information System (INIS)

    Soldatov, A.V.; Kravtsova, A.N.; Fedorovich, E.N.; Kurmaev, E.Z.; Moewes, A.

    2004-01-01

    Full text: The iron L 2,3 and carbon, nitrogen and oxygen Kα X-ray emission spectra (XES) of human hemoglobin have been recorded at the soft X-ray spectroscopy endstation on Undulator Beam line 8.0 at Advanced Light Source (ALS) located at the Lawrence Berkeley National Laboratory. The theoretical calculations of Fe L 3 -XES have been performed using ab initio code FEFF8.2. The calculations have been carried out for the structure of hemoglobin presented in PDB (entry 3HHB) as well as for the molecule with symmetrical heme plane. It was found that the Fe L 3 emission spectrum calculated for the ideal molecule agrees slightly better with the experiment as compared with those calculated for the real molecule. Thus, one can use the structure of the ideal molecule for theoretical Fe L 3 -XES simulations. The theoretical analysis has shown that the fist peak of experimental Fe L 3 - emission spectrum is enhanced by the nearest nitrogen atoms lying in heme plane around the central iron atom. The theoretical C K- and N K-XES spectra of hemoglobin have been calculated. A good agreement between theoretical and experimental spectra has been obtained. The distribution of the partial electronic densities of states in the valence and conduction bands of hemoglobin has been determined

  15. Conceptual Design of Dielectric Accelerating Structures for Intense Neutron and Monochromatic X-ray Sources

    Science.gov (United States)

    Blanovsky, Anatoly

    2004-12-01

    Bright compact photon sources, which utilize electron beam interaction with periodic structures, may benefit a broad range of medical, industrial and scientific applications. A class of dielectric-loaded periodic structures for hard and soft X-ray production has been proposed that would provide a high accelerating gradient when excited by an external RF and/or primary electron beam. Target-distributed accelerators (TDA), in which an additional electric field compensates for lost beam energy in internal targets, have been shown to provide the necessary means to drive a high flux subcritical reactor (HFSR) for nuclear waste transmutation. The TDA may also be suitable for positron and nuclear isomer production, X-ray lithography and monochromatic computer tomography. One of the early assumptions of the theory of dielectric wake-field acceleration was that, in electrodynamics, the vector potential was proportional to the scalar potential. The analysis takes into consideration a wide range of TDA design aspects including the wave model of observed phenomena, a layered compound separated by a Van der Waals gap and a compact energy source based on fission electric cells (FEC) with a multistage collector. The FEC is a high-voltage power source that directly converts the kinetic energy of the fission fragments into electrical potential of about 2MV.

  16. Heterophase fluctuation of omega phase and X-ray diffuse scattering from dual phase structure

    International Nuclear Information System (INIS)

    Farjami, Susan; Kubo, Hiroshi

    2003-01-01

    Heterophase fluctuation of athermal omega embryos has been analyzed by assuming a dual phase structure of omega embryos composed of omega and bcc matrix phase. The two-dimensional modulation of dual phase was suggested from the quantitative estimation of coherent free energy of omega embryos using microscopic theory of elasticity and the Landau anharmonic theory for phase transformation. The X-ray diffraction theory was developed in connection to the formation of omega embryos having the dual phase structure. The offset of the diffuse peak position from the ideal omega point in the X-ray diffraction pattern is attributed to the dual phase (incommensurate phase) of omega embryos. It was also shown that the ellipsoidal shape of the diffuse intensity tailing toward the fundamental spot of the matrix phase is originated from the equilibrium shape of the omega embryo. The quantitative estimation of elastic energy modulus (EEM) in the disordered bcc matrix and in the ordered bcc matrix indicates a difference in the deviation amount of the minimum point k(q m ) from the ideal omega point k(q ω ) and a difference in the elliptical shape of embryos

  17. Morphological and structural characterization of PHBV/organoclay nanocomposites by small angle X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Carli, Larissa N., E-mail: lncarli@ucs.br [Instituto de Quimica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves, 9500, Porto Alegre, 91501-970, RS (Brazil); Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, Rua Francisco Getulio Vargas, 1130, Caxias do Sul, 95070-560, RS (Brazil); Bianchi, Otavio, E-mail: obianchi@ucs.br [Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, Rua Francisco Getulio Vargas, 1130, Caxias do Sul, 95070-560, RS (Brazil); Machado, Giovanna, E-mail: giovannamachado@uol.com.br [Centro de Tecnologias Estrategicas do Nordeste, Av. Prof. Luiz Freire, 01, Cidade Universitaria, Recife, 50740-540, PE (Brazil); Programa de Pos-Graduacao de Materiais, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235, Recife, 50670-901, PE (Brazil); Crespo, Janaina S., E-mail: jscrespo@ucs.br [Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, Rua Francisco Getulio Vargas, 1130, Caxias do Sul, 95070-560, RS (Brazil); Mauler, Raquel S., E-mail: raquel.mauler@ufrgs.br [Instituto de Quimica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves, 9500, Porto Alegre, 91501-970, RS (Brazil)

    2013-03-01

    In this work, the morphological and structural behaviors of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) nanocomposites were investigated using small angle X-ray scattering (SAXS), wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The nanocomposites with 1, 3 and 5 wt.% of organically modified montmorillonite Cloisite Registered-Sign 30B (OMMT) were prepared by melt processing in a twin screw extruder using two different processing conditions (low and high shear intensity). The lamellar long period of the polymer was lower for the nanocomposites, with high polydispersity values. However, the crystalline thickness increased with the clay content and was independent of the processing conditions. This behavior resulted in a high linear crystallinity of the nanocomposites with 3 and 5 wt.% OMMT. The disruption factor ({beta}) was in agreement with the WAXD and TEM findings, indicating a good dispersion of the nanoparticles in the PHBV matrix with 3 wt.% of OMMT during the high shear intensity of melt processing. Highlights: Black-Right-Pointing-Pointer SAXS was used for morphological and crystalline studies of PHBV/OMMT nanocomposites. Black-Right-Pointing-Pointer The crystalline structure was influenced by the presence of clay. Black-Right-Pointing-Pointer The degree of clay dispersion in a polymer matrix was quantified. Black-Right-Pointing-Pointer The morphology comprised exfoliated particles, nanoscale and microscale clusters. Black-Right-Pointing-Pointer The results obtained by SAXS agreed well with TEM and WAXD results.

  18. Layered structure analysis of multilayers by X-ray reflectometry using the Cu-Kβ line

    International Nuclear Information System (INIS)

    Usami, Katsuhisa; Ueda, Kazuhiro; Hirano, Tatsumi; Hoshiya, Hiroyuki; Narishige, Shinji.

    1997-01-01

    The suitability of X-ray reflectometry using the Cu-K β line for layered structure analysis of NiFe/Cu/NiFe/Ta layered films was studied. Structural parameters such as film thickness, density, and interface width can be determined more accurately than by Cu-K α1 X-ray reflectometry, owing to the abnormal dispersion effect. The standard deviations in determination of film thicknesses were within ±0.3% for NiFe and Ta films and ±0.03 nm for 2 nm Cu film. Those for the densities and interface widths were within ±2% and ±0.04 nm for all films, respectively. Analysis of some layered films regarding the change in Cu film thickness showed that in all these samples the density of the films most closely reflected the density of bulk material, and the interface width between the upper NiFe and Cu films increased with increasing Cu film thickness. (author)

  19. Synthesis, spectroscopy, X-ray crystallography, and DFT computations of nanosized phosphazenes

    Czech Academy of Sciences Publication Activity Database

    Shariatinia, Z.; Moghadam, E.J.; Maghsoudi, N.; Mousavi, H.S.M.; Dušek, Michal; Eigner, Václav

    2015-01-01

    Roč. 641, č. 5 (2015), s. 967-978 ISSN 0044-2313 Grant - others:AV ČR(CZ) Praemium Academiae Institutional support: RVO:68378271 Keywords : phosphazene * ultrasonic * nanoparticle * x-ray crystallography * DFT calculation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.261, year: 2015

  20. A novel synthesis of polymeric CO via useful hard X-ray photochemistry

    Directory of Open Access Journals (Sweden)

    Michael Pravica

    2016-12-01

    Full Text Available We report on the synchrotron hard X-ray-induced decomposition of strontium oxalate (SrC2O4 pressurized to 7 GPa inside a diamond anvil cell (DAC. After some 4 h of irradiation in a white X-ray synchrotron beam, a dark reddish/brown region formed in the area of irradiation which was surrounded by a yellowish brown remainder in the rest of the sample. Upon depressurization of the sample to ambient conditions, the reacted/decomposed sample was recoverable as a dark brown/red and yellow waxy solid. Synchrotron infrared spectroscopy confirmed the strong presence of CO2 even under ambient conditions with the sample exposed to air and other strongly absorbing regions, suggesting that the sample may likely be polymerized CO (in part with dispersed CO2 and SrO trapped within the polymer. These results will have significant implications in the ability to readily produce and trap CO2 in situ via irradiation of a simple powder for useful hard X-ray photochemistry and in the ability to easily manufacture polymeric CO (via loading of powders in a DAC or high volume press without the need for the dangerous and complex loading of toxic CO. A novel means of X-ray-induced polymerization under extreme conditions has also been demonstrated.

  1. Local layer structure of smectic liquid crystals by X-ray micro-diffraction

    CERN Document Server

    Takanishi, Y

    2003-01-01

    The local layer structure of smectic liquid crystal has been measured using time-resolved synchrotron X-ray micro-diffraction. Typical layer disorders observed in surface stabilized (anti-) ferroelectric liquid crystals, i.e. a stripe texture, a needed-like defect and a zigzag defect, are directly analyzed. The detailed analysis slows that the surface anchoring force due to the interaction between the liquid crystal molecule and the alignment thin film plays an important role to realize both the static and dynamic local layer structures. The layer structure of the circular domain observed in the liquid crystal of bent-shaped molecules found to depend on the applied electric field though the optical micrograph shows little difference. The frustrated, double and single layer structures of the bent-shaped molecule liquid crystal are determined depending on the terminal alkyl chain length. (author)

  2. Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy and ultra-small angle X-ray scattering experiments

    CERN Document Server

    Marliere, C; Etienne, P; Woignier, T; Dieudonné, P; Phalippou, J

    2001-01-01

    During the last few years the bulk structure of silica aerogels has been extensively studied mainly by scattering techniques (neutrons, X-rays, light). It has been shown that small silica particles aggregate to constitute a fractal network. Its spatial extension and fractal dimension are strongly dependent on the synthesis conditions (e.g., pH of gelifying solutions). These typical lengths range from 1 to 10 nm. Ultra-small angle X-ray scattering (USAXS) and atomic force microscopy (AFM) experiments have been carried out on aerogels at different steps of densification. The results presented in this paper reveal the existence of a spatial arrangement of the solid part at a very large length scale. The evolution of this very large-scale structure during the densification process has been studied and reveals a contraction of this macro-structure made of aggregates of clusters. (16 refs).

  3. X-ray free electron laser and its application to 3-dimensional imaging of non-crystalline nano-structure

    International Nuclear Information System (INIS)

    Ishikawa, Tetsuya

    2007-01-01

    The Laser in the X-ray region has been anticipated to be realized as a light source to probe the nano-world. Free electron lasers using high energy electron accelerators have been promising the candidates. The finding of the principle of Self-Amplified Spontaneous Emission (SASE) resolved the technological difficulties accompanying the X-ray free electron laser, and the construction of large scale SASE facilities started in western countries. In Japan the construction of an SASE facility started in 2006 to be completed in 2010 at the site of the large synchrotron radiation facility, SPring-8 positioned as a 'critical technology of national importance' by the Japanese government. The principle of the X-ray free electron laser is explained and the outline of the Japanese facility construction plan is presented. Also the application of the X-ray laser to the imaging of non-crystalline nano-structure is introduced. (K.Yoshida)

  4. Microscopic bosonization of band structures: x-ray processes beyond the Fermi edge

    Science.gov (United States)

    Snyman, Izak; Florens, Serge

    2017-11-01

    Bosonization provides a powerful analytical framework to deal with one-dimensional strongly interacting fermion systems, which makes it a cornerstone in quantum many-body theory. However, this success comes at the expense of using effective infrared parameters, and restricting the description to low energy states near the Fermi level. We propose a radical extension of the bosonization technique that overcomes both limitations, allowing computations with microscopic lattice Hamiltonians, from the Fermi level down to the bottom of the band. The formalism rests on the simple idea of representating the fermion kinetic term in the energy domain, after which it can be expressed in terms of free bosonic degrees of freedom. As a result, one- and two-body fermionic scattering processes generate anharmonic boson-boson interactions, even in the forward channel. We show that up to moderate interaction strengths, these non-linearities can be treated analytically at all energy scales, using the x-ray emission problem as a showcase. In the strong interaction regime, we employ a systematic variational solution of the bosonic theory, and obtain results that agree quantitatively with an exact diagonalization of the original one-particle fermionic model. This provides a proof of the fully microscopic character of bosonization, on all energy scales, for an arbitrary band structure. Besides recovering the known x-ray edge singularity at the emission threshold, we find strong signatures of correlations even at emission frequencies beyond the band bottom.

  5. The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, D.; Barbrel, B.; Falcone, R. W. [Department of Physics, University of California, Berkeley, California 94720 (United States); Vorberger, J. [Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, 01187 Dresden (Germany); Helfrich, J.; Frydrych, S.; Ortner, A.; Otten, A.; Roth, F.; Schaumann, G.; Schumacher, D.; Siegenthaler, K.; Wagner, F.; Roth, M. [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt (Germany); Gericke, D. O.; Wünsch, K. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Bachmann, B.; Döppner, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Bagnoud, V.; Blažević, A. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); and others

    2015-05-15

    We present measurements of the complex ion structure of warm dense carbon close to the melting line at pressures around 100 GPa. High-pressure samples were created by laser-driven shock compression of graphite and probed by intense laser-generated x-ray sources with photon energies of 4.75 keV and 4.95 keV. High-efficiency crystal spectrometers allow for spectrally resolving the scattered radiation. Comparing the ratio of elastically and inelastically scattered radiation, we find evidence for a complex bonded liquid that is predicted by ab-initio quantum simulations showing the influence of chemical bonds under these conditions. Using graphite samples of different initial densities we demonstrate the capability of spectrally resolved x-ray scattering to monitor the carbon solid-liquid transition at relatively constant pressure of 150 GPa. Showing first single-pulse scattering spectra from cold graphite of unprecedented quality recorded at the Linac Coherent Light Source, we demonstrate the outstanding possibilities for future high-precision measurements at 4th Generation Light Sources.

  6. Finite difference method calculations of X-ray absorption fine structure for copper

    Energy Technology Data Exchange (ETDEWEB)

    Bourke, J.D. [School of Physics, University of Melbourne, Parkville, Vic 3010 (Australia); Chantler, C.T. [School of Physics, University of Melbourne, Parkville, Vic 3010 (Australia)]. E-mail: chantler@physics.unimelb.edu.au; Witte, C. [School of Physics, University of Melbourne, Parkville, Vic 3010 (Australia)

    2007-01-15

    The finite difference method is extended to calculate X-ray absorption fine structure (XAFS) for solid state copper. These extensions include the incorporation of a Monte Carlo frozen phonon technique to simulate the effect of thermal vibrations under a correlated Debye-Waller model, and the inclusion of broadening effects from inelastic processes. Spectra are obtained over an energy range in excess of 300 eV above the K absorption edge-more than twice the greatest energy range previously reported for a solid state calculation using this method. We find this method is highly sensitive to values of the photoelectron inelastic mean free path, allowing us to probe the accuracy of current models of this parameter, particularly at low energies. We therefore find that experimental data for the photoelectron inelastic mean free path can be obtained by this method. Our results compare favourably with high precision measurements of the X-ray mass attenuation coefficient for copper, reaching agreement to within 3%, and improving previous results using the finite difference method by an order of magnitude.

  7. Complex Structure of Galaxy Cluster Abell 1689: Evidence for a Merger from X-Ray Data?

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, K

    2004-01-29

    Abell 1689 is a galaxy cluster at z = 0:183 where previous measurements of its mass using various techniques gave discrepant results. We present a new detailed measurement of the mass with the data based on X-ray observations with the European Photon Imaging Camera aboard the XMM-Newton Observatory, determined by using an unparameterized deprojection technique. Fitting the total mass profile to a Navarro-Frenk-White model yields halo concentration c = 7.2{sub -2.4}{sup +1.6} and r{sub 200} = 1.13 {+-} 0.21 h{sup -1} Mpc, corresponding to a mass which is less than half of what is found from gravitational lensing. Adding to the evidence of substructure from optical observations, X-ray analysis shows a highly asymmetric temperature profile and a non-uniform redshift distribution implying large scale relative motion of the gas. A lower than expected gas mass fraction f{sub gas} = 0.072 {+-} 0.008 (for a flat {Lambda}CDM cosmology) suggests a complex spatial and/or dynamical structure. We also find no signs of any additional absorbing component previously reported on the basis of the Chandra data, confirming the XMM low energy response using data from ROSAT.

  8. Extended x-ray absorption fine structure: Studies of zinc-neutralized sulfonated polystyrene ionomers

    International Nuclear Information System (INIS)

    Ding, Y.S.; Yarusso, D.J.; Pan, H.K.D.; Cooper, S.L.

    1984-01-01

    Extended x-ray absorption fine structure (EXAFS) measurements were performed on a series of zinc-neutralized sulfonated polystyrene ionomers and the local structure around the zinc atom was determined. An interference effect in the EXAFS signal between sulfur and oxygen atoms was found to be significant in these materials. A model for the local structure in the zinc-neutralized sulfonated polystyrene ionomers is proposed which suggests a highly ordered tetrahedral coordination of oxygen around the zinc atoms at a distance of 1.97 +- 0.02 A. In addition there are four sulfur atoms and four oxygen atoms at a distance of 3.15 +- 0.05 A. No zinc-zinc coordination within 5 A was detected in this study

  9. Structure factor of dimyristoylphosphatidylcholine unilamellar vesicles: small-angle x-ray scattering study

    International Nuclear Information System (INIS)

    Kiselev, M.A.; Aksenov, V.L.; Lombardo, D.; Kisselev, A.M.; Lesieur, P.

    2003-01-01

    Small-angle X-ray scattering (SAXS) experiments have been performed on dimyristoylphosphatidylcholine (DMPC) unilamellar vesicles in 40% aqueous sucrose solution. Model of separated form factors was applied for the evaluation of SAXS curves from large unilamellar vesicles. For the first time vesicle structure factor, polydispersity, average radius and membrane thickness were calculated simultaneously from the SAXS curves at T=30 deg C for DMPC concentrations in the range from 15 to 75 mM (1-5% w/w). Structure factor correction to the scattering curve was shown to be negligibly small for the lipid concentration of 15 mM (1% w/w). It was proved to be necessary to introduce structure factor correction to the scattering curves for lipid concentrations ≥ 30 mM (2% w/w)

  10. Structure-activity relationships of heterogeneous catalysts from time-resolved X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Ressler, T.; Jentoft, R.E.; Wienold, J.; Girgsdies, F.; Neisius, T.; Timpe, O.

    2003-01-01

    Knowing the composition and the evolution of the bulk structure of a heterogeneous catalyst under working conditions (in situ) is a pre-requisite for understanding structure-activity relationships. X-ray absorption spectroscopy can be employed to study a catalytically active material in situ. In addition to steady-state investigations, the technique permits experiments with a time-resolution in the sub-second range to elucidate the solid-state kinetics of the reactions involved. Combined with mass spectrometry, the evolution of the short-range order structure of a heterogeneous catalyst, the average valence of the constituent metals, and the phase composition can be obtained. Here we present results obtained from time-resolved studies on the reduction of MoO 3 in propene and in propene and oxygen

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

    International Nuclear Information System (INIS)

    Abramova, V. V.; Sinitskii, A. S.; Grigor'eva, N. A.; Grigor'ev, S. V.; Belov, D. V.; Petukhov, A. V.; Mistonov, A. A.; Vasil'eva, A. V.; Tret'yakov, Yu. D.

    2009-01-01

    The results of an ultrasmall-angle X-ray scattering study of iron(III) oxide inverse opal thin films are presented. The photonic crystals examined are shown to have fcc structure with amount of stacking faults varying among the samples. The method used in this study makes it possible to easily distinguish between samples with predominantly twinned fcc structure and nearly perfect fcc stacking. The difference observed between samples fabricated under identical conditions is attributed to random layer stacking in the self-assembled colloidal crystals used as templates for fabricating the inverse opals. The present method provides a versatile tool for analyzing photonic crystal structure in studies of inverse opals made of various materials, colloidal crystals, and three-dimensional photonic crystals of other types.

  12. Structure Factor of Dimyristoylphosphatidylcholine Unilamellar Vesicles Small-Angle X-Ray Scattering Study

    CERN Document Server

    Kiselev, M A; Kisselev, A M; Lesieur, P; Aksenov, V L

    2003-01-01

    Small-angle X-ray scattering (SAXS) experiments have been performed on dimyristoylphosphatidylcholine (DMPC) unilamellar vesicles in 40 % aqueous sucrose solution. Model of separated form factors was applied for the evaluation of SAXS curves from large unilamellar vesicles. For the first time vesicle structure factor, polydispersity, average radius and membrane thickness were calculated simultaneously from the SAXS curves at T=306{\\circ}C for DMPC concentrations in the range from 15 to 75 mM (1-5 % w/w). Structure factor correction to the scattering curve was shown to be negligibly small for the lipid concentration of 15 mM (1 % w/w). It was proved to be necessary to introduce structure factor correction to the scattering curves for lipid concentrations {\\ge}30 mM (2 % w/w).

  13. High pressure study of nanostructured Cu2Sb by X-ray Diffraction, Extended X-ray Absorption fine structure and Raman measurements

    International Nuclear Information System (INIS)

    Souza, Sergio Michielon de; Triches, Daniela Menegon; Lima, Joao Cardoso de; Polian, Alain

    2016-01-01

    Full text: Nanostructured tetragonal Cu 2 Sb was prepared by mechanical alloying and its stability was studied as a function of pressure using synchrotron X-ray diffraction (XRD) Extended X-Ray Absorption Fine Structure (EXAFS) and Raman spectroscopy. The high pressure XRD data were collected at 0.6, 1.1, 2.2, 3.4, 5.0, 7.1, 8.0, 9.9, 14.8, 18.7, 23.2, 29.3 and 40.6 GPa in the ELETTRA synchrotron (Italy) with λ = 0.68881 Å. The high pressure EXAFS measurements were carried out in the Soleil synchrotron (France) in 0.6, 1.8, 3.0, 4.5, 6.1, 8.0, 10.3, 12.7, 15.5, 18.0, 19.0, 20.0, 22.1, 23.9, 26.3 and 29.4 GPa and the high pressure Raman spectroscopy in the Institut de Mineralogie et de Physique des Milieux Condenses (France) collected at 0.1, 1.6, 3.7, 6.7, 11.2, 15.1, 19.4, 24.5, 30.8, 36.3, 41.3 and 44.5 GPa. The results show high structural and optical phase stability. The moduli bulk and its derivatives were obtained by using the Birch-Murnaghan equation of states to the XRD and EXAFS results. The evolution of the Raman modes and the bulk moduli were used to obtain the Grueneisen parameters. (author)

  14. Phase Transformation and Lithiation Effect on Electronic Structure of LixFePO4 : An In-Depth Study by Soft X-ray and Simulations

    NARCIS (Netherlands)

    Liu, Xiaosong; Liu, Jun; Qiao, Ruimin; Yu, Yan; Li, Hong; Suo, Liumin; Hu, Yong-sheng; Chuang, Yi-De; Shu, Guojiun; Chou, Fangcheng; Weng, Tsu-Chien; Nordlund, Dennis; Sokaras, Dimosthenis; Wang, Yung Jui; Lin, Hsin; Barbiellini, Bernardo; Bansil, Arun; Song, Xiangyun; Liu, Zhi; Yan, Shishen; Liu, Gao; Qjao, Shan; Richardson, Thomas J.; Prendergast, David; Hussain, Zahid; de Groot, Frank M. F.|info:eu-repo/dai/nl/08747610X; Yang, Wanli

    2012-01-01

    Through soft X-ray absorption spectroscopy, hard X-ray Raman scattering, and theoretical simulations, we provide the most in-depth and systematic study of the phase transformation and (de)lithiation effect on electronic structure in LixFePO4 nanoparticles and single crystals. Soft X-ray reveals

  15. Structural Characterization of Doped GaSb Single Crystals by X-ray Topography

    Energy Technology Data Exchange (ETDEWEB)

    Honnicke, M.G.; Mazzaro, I.; Manica, J.; Benine, E.; M da Costa, E.; Dedavid, B. A.; Cusatis, C.; Huang, X. R.

    2009-09-13

    We characterized GaSb single crystals containing different dopants (Al, Cd and Te), grown by the Czochralski method, by x-ray topography and high angular resolution x-ray diffraction. Lang topography revealed dislocations parallel and perpendicular to the crystal's surface. Double-crystal GaSb 333 x-ray topography shows dislocations and vertical stripes than can be associated with circular growth bands. We compared our high-angular resolution x-ray diffraction measurements (rocking curves) with the findings predicted by the dynamical theory of x-ray diffraction. These measurements show that our GaSb single crystals have a relative variation in the lattice parameter ({Delta}d/d) on the order of 10{sup -5}. This means that they can be used as electronic devices (detectors, for example) and as x-ray monochromators.

  16. Fine surface structure of unfixed and hydrated macrophages observed by laser-plasma x-ray contact microscopy

    International Nuclear Information System (INIS)

    Yamamoto, Yoshimasa; Friedman, Herman; Yoshimura, Hideyuki; Kinjo, Yasuhito; Shioda, Seiji; Debari, Kazuhiro; Shinohara, Kunio; Rajyaguru, Jayshree; Richardson, Martin

    2000-01-01

    A compact, high-resolution, laser-plasma, x-ray contact microscope using a table-top Nd:glass laser system has been developed and utilized for the analysis of the surface structure of live macrophages. Fine fluffy surface structures of murine peritoneal macrophages, which were live, hydrolyzed and not sliced and stained, were observed by the x-ray microscope followed by analysis using an atomic force microscopy. In order to compare with other techniques, a scanning electron microscopy (SEM) was utilized to observe the surface structure of the macrophages. The SEM offered a fine whole cell image of the same macrophages, which were fixed and dehydrated, but the surfaces were ruffled and different from that of x-ray images. A standard light microscope was also utilized to observe the shape of live whole macrophages. Light microscopy showed some fluffy surface structures of the macrophages, but the resolution was too low to observe the fine structures. Thus, the findings of fine fluffy surface structures of macrophages by x-ray microscopy provide valuable information for studies of phagocytosis, cell spreading and adherence, which are dependent on the surface structure of macrophages. Furthermore, the present study also demonstrates the usefulness of x-ray microscopy for analysis of structures of living cells

  17. X-ray detector

    International Nuclear Information System (INIS)

    Whetten, N.R.; Houston, J.M.

    1977-01-01

    An ionization chamber for use in determining the spatial distribution of x-ray photons in tomography systems comprises a plurality of substantially parallel, planar anodes separated by parallel, planar cathodes and enclosed in a gas of high atomic weight at a pressure from approximately 10 atmospheres to approximately 50 atmospheres. The cathode and anode structures comprise metals which are substantially opaque to x-ray radiation and thereby tend to reduce the resolution limiting effects of x-ray fluoresence in the gas. In another embodiment of the invention the anodes comprise parallel conductive bars disposed between two planar cathodes. Guard rings eliminate surface leakage currents between adjacent electrodes. 8 figures

  18. Synthesis, spectroscopic and DNA binding ability of Co{sup II}, Ni{sup II}, Cu{sup II} and Zn{sup II} complexes of Schiff base ligand (E)-1-(((1H-benzo[d]imidazol-2-yl)methylimino)methyl)naphthalen-2-ol. X-ray crystal structure determination of cobalt (II) complex

    Energy Technology Data Exchange (ETDEWEB)

    Yarkandi, Naeema H. [Chemistry Department, Faculty of Applied Science, Umm Al–Qura University, Makkah (Saudi Arabia); El-Ghamry, Hoda A., E-mail: helghamrymo@yahoo.com [Chemistry Department, Faculty of Applied Science, Umm Al–Qura University, Makkah (Saudi Arabia); Chemistry Department, Faculty of Science, Tanta University, Tanta (Egypt); Gaber, Mohamed [Chemistry Department, Faculty of Science, Tanta University, Tanta (Egypt)

    2017-06-01

    A novel Schiff base ligand, (E)-1-(((1H-benzo[d]imidazol-2-yl)methylimino)methyl)naphthalen-2-ol (HL), has been designed and synthesized in addition to its metal chelates [Co(L){sub 2}]·l2H{sub 2}O, [Ni(L)Cl·(H{sub 2}O){sub 2}].5H{sub 2}O, [Cu(L)Cl] and [Zn(L)(CH{sub 3}COO)]. The structures of the isolated compounds have been confirmed and identified by means of different spectral and physicochemical techniques including CHN analysis, {sup 1}H &{sup 13}C NMR, mass spectral analysis, molar conductivity measurement, UV–Vis, infrared, magnetic moment in addition to TGA technique. The infrared spectral results ascertained that the ligand acts as monobasic tridentate binding to the metal centers via deprotonated hydroxyl oxygen, azomethine and imidazole nitrogen atoms. The UV–Vis, magnetic susceptibility and molar conductivity data implied octahedral geometry for Co(II) & Ni(II) complexes, tetrahedral for Zn(II) complex and square planar for Cu(II) complex. X-ray structural analysis of Co(II) complex 1 has been reported and discussed. Moreover, the type of interaction between the ligand & its complexes towards salmon sperm DNA (SS-DNA) has been examined by the measurement of absorption spectra and viscosity which confirmed that the ligand and its complexes interact with DNA via intercalation interaction as concluded from the values of binding constants (K{sub b}). - Highlights: • Synthesis of Co{sup II}, Ni{sup II}, Cu{sup II} and Zn{sup II} complexes of the Schiff base ligand based on 2-(aminomethyl)benzimidazole moiety. • The constitutions and structures of the ligand and complexes were elucidated. • Molecular structure of Co{sup II} complex was confirmed by single crystal X-ray diffraction method. • The ligand and its complexes interact with SS-DNA via intercalation mods.

  19. X-rays and magnetism

    International Nuclear Information System (INIS)

    Fischer, Peter; Ohldag, Hendrik

    2015-01-01

    Magnetism is among the most active and attractive areas in modern solid state physics because of intriguing phenomena interesting to fundamental research and a manifold of technological applications. State-of-the-art synthesis of advanced magnetic materials, e.g. in hybrid structures paves the way to new functionalities. To characterize modern magnetic materials and the associated magnetic phenomena, polarized x-rays have emerged as unique probes due to their specific interaction with magnetic materials. A large variety of spectroscopic and microscopic techniques have been developed to quantify in an element, valence and site-sensitive way properties of ferro-, ferri-, and antiferromagnetic systems, such as spin and orbital moments, and to image nanoscale spin textures and their dynamics with sub-ns time and almost 10 nm spatial resolution. The enormous intensity of x-rays and their degree of coherence at next generation x-ray facilities will open the fsec time window to magnetic studies addressing fundamental time scales in magnetism with nanometer spatial resolution. This review will give an introduction into contemporary topics of nanoscale magnetic materials and provide an overview of analytical spectroscopy and microscopy tools based on x-ray dichroism effects. Selected examples of current research will demonstrate the potential and future directions of these techniques. (report on progress)

  20. X-ray physico-chemical imaging during activation of cobalt-based Fischer-Tropsch synthesis catalysts

    Science.gov (United States)

    Beale, Andrew M.; Jacques, Simon D. M.; Di Michiel, Marco; Mosselmans, J. Frederick W.; Price, Stephen W. T.; Senecal, Pierre; Vamvakeros, Antonios; Paterson, James

    2017-11-01

    The imaging of catalysts and other functional materials under reaction conditions has advanced significantly in recent years. The combination of the computed tomography (CT) approach with methods such as X-ray diffraction (XRD), X-ray fluorescence (XRF) and X-ray absorption near-edge spectroscopy (XANES) now enables local chemical and physical state information to be extracted from within the interiors of intact materials which are, by accident or design, inhomogeneous. In this work, we follow the phase evolution during the initial reduction step(s) to form Co metal, for Co-containing particles employed as Fischer-Tropsch synthesis (FTS) catalysts; firstly, working at small length scales (approx. micrometre spatial resolution), a combination of sample size and density allows for transmission of comparatively low energy signals enabling the recording of `multimodal' tomography, i.e. simultaneous XRF-CT, XANES-CT and XRD-CT. Subsequently, we show high-energy XRD-CT can be employed to reveal extent of reduction and uniformity of crystallite size on millimetre-sized TiO2 trilobes. In both studies, the CoO phase is seen to persist or else evolve under particular operating conditions and we speculate as to why this is observed. This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.

  1. xMDFF: molecular dynamics flexible fitting of low-resolution X-ray structures

    International Nuclear Information System (INIS)

    McGreevy, Ryan; Singharoy, Abhishek; Li, Qufei; Zhang, Jingfen; Xu, Dong; Perozo, Eduardo; Schulten, Klaus

    2014-01-01

    A new real-space refinement method for low-resolution X-ray crystallography is presented. The method is based on the molecular dynamics flexible fitting protocol targeted at addressing large-scale deformations of the search model to achieve refinement with minimal manual intervention. An explanation of the method is provided, augmented by results from the refinement of both synthetic and experimental low-resolution data, including an independent electrophysiological verification of the xMDFF-refined crystal structure of a voltage-sensor protein. X-ray crystallography remains the most dominant method for solving atomic structures. However, for relatively large systems, the availability of only medium-to-low-resolution diffraction data often limits the determination of all-atom details. A new molecular dynamics flexible fitting (MDFF)-based approach, xMDFF, for determining structures from such low-resolution crystallographic data is reported. xMDFF employs a real-space refinement scheme that flexibly fits atomic models into an iteratively updating electron-density map. It addresses significant large-scale deformations of the initial model to fit the low-resolution density, as tested with synthetic low-resolution maps of d-ribose-binding protein. xMDFF has been successfully applied to re-refine six low-resolution protein structures of varying sizes that had already been submitted to the Protein Data Bank. Finally, via systematic refinement of a series of data from 3.6 to 7 Å resolution, xMDFF refinements together with electrophysiology experiments were used to validate the first all-atom structure of the voltage-sensing protein Ci-VSP

  2. xMDFF: molecular dynamics flexible fitting of low-resolution X-ray structures

    Energy Technology Data Exchange (ETDEWEB)

    McGreevy, Ryan; Singharoy, Abhishek [University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Li, Qufei [The University of Chicago, Chicago, IL 60637 (United States); Zhang, Jingfen; Xu, Dong [University of Missouri, Columbia, MO 65211 (United States); Perozo, Eduardo [The University of Chicago, Chicago, IL 60637 (United States); Schulten, Klaus, E-mail: kschulte@ks.uiuc.edu [University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

    2014-09-01

    A new real-space refinement method for low-resolution X-ray crystallography is presented. The method is based on the molecular dynamics flexible fitting protocol targeted at addressing large-scale deformations of the search model to achieve refinement with minimal manual intervention. An explanation of the method is provided, augmented by results from the refinement of both synthetic and experimental low-resolution data, including an independent electrophysiological verification of the xMDFF-refined crystal structure of a voltage-sensor protein. X-ray crystallography remains the most dominant method for solving atomic structures. However, for relatively large systems, the availability of only medium-to-low-resolution diffraction data often limits the determination of all-atom details. A new molecular dynamics flexible fitting (MDFF)-based approach, xMDFF, for determining structures from such low-resolution crystallographic data is reported. xMDFF employs a real-space refinement scheme that flexibly fits atomic models into an iteratively updating electron-density map. It addresses significant large-scale deformations of the initial model to fit the low-resolution density, as tested with synthetic low-resolution maps of d-ribose-binding protein. xMDFF has been successfully applied to re-refine six low-resolution protein structures of varying sizes that had already been submitted to the Protein Data Bank. Finally, via systematic refinement of a series of data from 3.6 to 7 Å resolution, xMDFF refinements together with electrophysiology experiments were used to validate the first all-atom structure of the voltage-sensing protein Ci-VSP.

  3. X-ray magnetic microscopy for correlations between magnetic domains and crystal structure

    International Nuclear Information System (INIS)

    Denbeaux, G.; Anderson, E.; Bates, B.; Chao, W.; Liddle, J.A.; Harteneck, B.; Pearson, A.; Salmassi, F.; Schneider, G.; Fischer, P.; Eimuller, T.; Taylor, S.; Chang, H.; Kusinski, G.J.

    2002-01-01

    Accurately determining the resolution of x-ray microscopes has been a challenge because good test patterns for x-ray microscopy have been hard to make. We report on a sputter-deposited multilayer imaged in cross section as a test pattern with small features and high aspect ratios. One application of high-resolution imaging is magnetic materials. Off-axis bend magnet radiation is known to have a component of circular polarization which can be used for x-ray magnetic circular dichroism. We calculate the integrated circular polarization collected by the illumination optics in the XM-1 full-field x-ray microscope. (authors)

  4. X-ray Tomography Characterisation of Lattice Structures Processed by Selective Electron Beam Melting

    Directory of Open Access Journals (Sweden)

    Everth Hernández-Nava

    2017-08-01

    Full Text Available Metallic lattice structures intentionally contain open porosity; however, they can also contain unwanted closed porosity within the structural members. The entrained porosity and defects within three different geometries of Ti-6Al-4V lattices, fabricated by Selective Electron Beam Melting (SEBM, is assessed from X-ray computed tomography (CT scans. The results suggest that horizontal struts that are built upon loose powder show particularly high (~20 × 10−3 vol % levels of pores, as do nodes at which many (in our case 24 struts meet. On the other hand, for struts more closely aligned (0° to 54° to the build direction, the fraction of porosity appears to be much lower (~0.17 × 10−3% arising mainly from pores contained within the original atomised powder particles.

  5. Variability: A X-ray ruler for the AGN structure model

    Directory of Open Access Journals (Sweden)

    Guainazzi M.

    2012-12-01

    Full Text Available Validating our understanding of the innermost structure of Active Galactic Nuclei (AGN would require resolving sub-parsec scales. Lacking adequate direct imaging, X-ray astronomy can still contribute to this undertaking through the study of spectral variability on time-scales from days to years. This bears information on the location of gaseous and dusty systems in the innermost regions around the accreting supermassive black hole. In this paper I discuss the application of this concept in two specific contexts: a “fast” column density variations in heavily obscured AGN; b reverberation of optically-thick reprocessing. These results lend support to a scenario where obscuration and optically thick reprocessing are due to a variety of different systems, ranging from the Broad Line Regions to a clumpy structure extended on larger scales up to hundreds of parsecs.

  6. Electronic Structures of Purple Bronze KMo6O17 Studied by X-Ray Photoemission Spectra

    Science.gov (United States)

    Qin, Xiaokui; Wei, Junyin; Shi, Jing; Tian, Mingliang; Chen, Hong; Tian, Decheng

    X-ray photoemission spectroscopy study has been performed for the purple bronze KMo6O17. The structures of conduction band and valence band are analogous to the results of ultraviolet photoemission spectra and are also consistent with the model of Travaglini et al., but the gap between conduction and valence band is insignificant. The shape of asymmetric and broadening line of O-1s is due to unresolved contributions from the many inequivalent oxygen sites in this crystal structure. Mo 3d core-level spectrum reveals that there are two kinds of valence states of Molybdenum (Mo+5 and Mo+6). The calculated average valence state is about +5.6, which is consistent with the expectation value from the composition of this material. The tail of Mo-3d spectrum toward higher binding energy is the consequence of the excitation of electron-hole pairs with singularity index of 0.21.

  7. Probing chemistry within the membrane structure of wood with soft X-ray spectral microscopy

    International Nuclear Information System (INIS)

    Cody, George D.

    2000-01-01

    Scanning Transmission Soft X-ray spectral microscopy on Carbon's 1s absorption edge reveals the distribution of structural biopolymers within cell membrane regions of modern cedar and oak. Cellulose is extremely susceptible to beam damage. Spectroscopic studies of beam damage reveals that the chemical changes resulting from secondary electron impact may be highly selective and is consistent with hydroxyl eliminations and structural rearrangement of pyranose rings in alpha-cellulose to hydroxyl substituted γ pyrones. A study of acetylated cellulose demonstrates significantly different chemistry; principally massive decarboxylation. Defocusing the beam to a 2 μm spot size allows for the acquisition of 'pristine' cellulose spectra. Spectral deconvolution is used to assess the distribution of lignin and cellulose in the different regions of the cell membrane. Using the intensity of the hydroxylated aromatic carbons 1s-π * transition, the ratio of coniferyl and syringyl based lignin within the middle lamellae and secondary cell wall of oak, an angiosperm can be determined

  8. Soft x-ray resonant diffraction study of magnetic structure in magnetoelectric Y-type hexaferrite

    Science.gov (United States)

    Ueda, H.; Tanaka, Y.; Wakabayashi, Y.; Kimura, T.

    2018-05-01

    The effect of magnetic field on the magnetic structure associated with magnetoelectric properties in a Y-type hexaferrite, Ba1.3Sr0.7CoZnFe11AlO22, was investigated by utilizing the soft x-ray resonant diffraction technique. In this hexaferrite, the so-called alternating longitudinal conical phase is stabilized at room temperature and zero magnetic field. Below room temperature, however, this phase is transformed into the so-called transverse conical phase by applying an in-plane magnetic field (≈ 0.3 T). The transverse conical phase persists even after removing the magnetic field. The magnetoelectricity, which is magnetically-induced electric polarization, observed in the hexaferrite is discussed in terms of the temperature-dependent magnetic structure at zero field.

  9. A method for measuring the time structure of synchrotron x-ray beams

    International Nuclear Information System (INIS)

    Moses, W.W.; Derenzo, S.E.

    1989-08-01

    We describe a method employing a plastic scintillator coupled to a fast photomultiplier tube to generate a timing pulse from the x-ray bursts emitted from a synchrotron radiation source. This technique is useful for performing synchrotron experiments where detailed knowledge of the timing distribution is necessary, such as time resolved spectroscopy or fluorescence lifetime experiments. By digitizing the time difference between the timing signal generated on one beam crossing with the timing signal generated on the next beam crossing, the time structure of a synchrotron beam can be analyzed. Using this technique, we have investigated the single bunch time structure at the National Synchrotron Light Source (NSLS) during pilot runs in January, 1989, and found that the majority of the beam (96%) is contained in one rf bucket, while the remainder of the beam (4%) is contained in satellite rf buckets preceeding and following the main rf bucket by 19 ns. 1 ref., 4 figs

  10. On the Origin of Hard X-ray Structures in the VELA Supernova Remnant

    Science.gov (United States)

    Gvaramadze, V. V.

    1998-12-01

    We propose an alternative explanation for the origin of two hard X-ray structures recently discovered in the central part of the Vela supernova remnant (SNR) by Willmore et al. (1992, MNRAS, 254, 139) and Markwardt & Ogelman (1995, Nature, 375, 40; 1997, ApJ, 480, L13), and interpreted as a plerion and a pulsar jet respectively. We suggest that the first structure is a dense material shed by the supernova progenitor star during the red supergiant stage, and reheated after the supernova exploded, while the "jet" is simply a dense filament in the Vela SNR's general shell, whose origin is connected with the Rayleigh-Taylor instability in the (main-sequence) wind-driven shell reaccelerated by the supernova blast wave.

  11. The structure of para-toluidine by X-ray and neutron diffraction

    International Nuclear Information System (INIS)

    Bertinotti, A.L.

    1965-12-01

    The crystal and molecular structure of para-toluidine has been solved by X-ray and neutron diffraction counter techniques. The molecules are arranged in the form of infinite chains in the crystal, each molecule being linked to two neighbours by hydrogen bonds. The presence of the H bonds makes clear the difference in the melting points between para-toluidine and benzene hydrocarbons of related symmetry and molecular weight. Their direction accounts for the (001) cleavage and the growth anisotropy of crystals from supersaturated vapour phase. A structure-seeking method by computer has been elaborated, using lattice energy calculations applied to molecules treated as rigid bodies and making use of a simplex method for function minimization without calculation of derivatives. The way the available information is handled allows to increase the range of convergence, as shown in the case of para-toluidine. (author) [fr

  12. Synthesis, characterization and in vitro cytotoxicity of Co(II) complexes with N6-substituted adenine derivatives: X-ray structures of 6-(4-chlorobenzylamino)purin-di-ium diperchlorate dihydrate and [Co6(μ-L6)4Cl8(DMSO)10] · 4DMSO

    Czech Academy of Sciences Publication Activity Database

    Klanicová, A.; Trávníček, Zdeněk; Popa, Igor; Čajan, Michal; Doležal, Karel

    2006-01-01

    Roč. 25, č. 6 (2006), s. 1421-1432 ISSN 0277-5387 R&D Projects: GA ČR GA203/04/1168 Institutional research plan: CEZ:AV0Z50380511 Keywords : Cobalt(II) complexes * X-ray structures * Cytokinins Subject RIV: CA - Inorganic Chemistry Impact factor: 1.843, year: 2006

  13. Binary population synthesis study of the supersoft X-ray phase of single degenerate type Ia supernova progenitors

    International Nuclear Information System (INIS)

    Meng Xiangcun; Yang Wuming

    2011-01-01

    In the single degenerate (SD) scenario for type Ia supernovae (SNe Ia), a mass-accreting white dwarf is expected to experience a supersoft X-ray source (SSS) phase. However, some recent observations showed that the expected number of mass-accreting WDs is much lower than that predicted from theory, regardless of whether they are in spiral or elliptical galaxies. In this paper, we performed a binary population synthesis study on the relative duration of the SSS phase to their whole mass-increasing phase of WDs leading to SNe Ia. We found that for about 40% of the progenitor systems, the relative duration is shorter than 2% and the evolution of the mean relative duration shows that it is always smaller than 5%, both for young and old SNe Ia. In addition, before the SNe Ia explosions, more than 55% of the progenitor systems were experiencing a dwarf novae phase and no more than 10% were staying in the SSS phase. These results are consistent with the recent observations and imply that both in early- and late-type galaxies, only a small fraction of mass-accreting WDs resulting in SNe Ia contributes to the supersoft X-ray flux. So, although our results are not directly related to the X-ray output of the SN Ia progenitor, the low supersoft X-ray luminosity observed in early type galaxies may not be able to exclude the validity of the SD model. On the contrary, it is evidence to support the SD scenario.

  14. A comparison of X-ray and calculated structures of the enzyme MTH1.

    Science.gov (United States)

    Ryan, Hannah; Carter, Megan; Stenmark, Pål; Stewart, James J P; Braun-Sand, Sonja B

    2016-07-01

    Modern computational chemistry methods provide a powerful tool for use in refining the geometry of proteins determined by X-ray crystallography. Specifically, computational methods can be used to correctly place hydrogen atoms unresolved by this experimental method and improve bond geometry accuracy. Using the semiempirical method PM7, the structure of the nucleotide-sanitizing enzyme MTH1, complete with hydrolyzed substrate 8-oxo-dGMP, was optimized and the resulting geometry compared with the original X-ray structure of MTH1. After determining hydrogen atom placement and the identification of ionized sites, the charge distribution in the binding site was explored. Where comparison was possible, all the theoretical predictions were in good agreement with experimental observations. However, when these were combined with additional predictions for which experimental observations were not available, the result was a new and alternative description of the substrate-binding site interaction. An estimate was made of the strengths and weaknesses of the PM7 method for modeling proteins on varying scales, ranging from overall structure to individual interatomic distances. An attempt to correct a known fault in PM7, the under-estimation of steric repulsion, is also described. This work sheds light on the specificity of the enzyme MTH1 toward the substrate 8-oxo-dGTP; information that would facilitate drug development involving MTH1. Graphical Abstract Overlay of the backbone traces of the two MTH1 protein chains (green and orange respectively) in PDB 3ZR0 and the equivalent PM7 structures (magenta and cyan respectively) each optimized separately.

  15. X-ray structural studies of quinone reductase 2 nanomolar range inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Pegan, Scott D.; Sturdy, Megan; Ferry, Gilles; Delagrange, Philippe; Boutin, Jean A.; Mesecar, Andrew D. (IdRS); (Purdue); (Colorado); (UIC)

    2011-09-06

    Quinone reductase 2 (QR2) is one of two members comprising the mammalian quinone reductase family of enzymes responsible for performing FAD mediated reductions of quinone substrates. In contrast to quinone reductase 1 (QR1) which uses NAD(P)H as its co-substrate, QR2 utilizes a rare group of hydride donors, N-methyl or N-ribosyl nicotinamide. Several studies have linked QR2 to the generation of quinone free radicals, several neuronal degenerative diseases, and cancer. QR2 has been also identified as the third melatonin receptor (MT3) through in cellulo and in vitro inhibition of QR2 by traditional MT3 ligands, and through recent X-ray structures of human QR2 (hQR2) in complex with melatonin and 2-iodomelatonin. Several MT3 specific ligands have been developed that exhibit both potent in cellulo inhibition of hQR2 nanomolar, affinity for MT3. The potency of these ligands suggest their use as molecular probes for hQR2. However, no definitive correlation between traditionally obtained MT3 ligand affinity and hQR2 inhibition exists limiting our understanding of how these ligands are accommodated in the hQR2 active site. To obtain a clearer relationship between the structures of developed MT3 ligands and their inhibitory properties, in cellulo and in vitro IC{sub 50} values were determined for a representative set of MT3 ligands (MCA-NAT, 2-I-MCANAT, prazosin, S26695, S32797, and S29434). Furthermore, X-ray structures for each of these ligands in complex with hQR2 were determined allowing for a structural evaluation of the binding modes of these ligands in relation to the potency of MT3 ligands.

  16. Structural characterization of cellulosic materials using x-ray and neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Penttila, P.

    2013-11-01

    Cellulosic biomass can be used as a feedstock for sustainable production of biofuels and various other products. A complete utilization of the raw material requires understanding on its structural aspects and their role in the various processes. In this thesis, x-ray and neutron scattering methods were applied to study the structure of various cellulosic materials and how they are affected in different processes. The obtained results were reviewed in the context of a model for the cellulose nanostructure. The dimensions of cellulose crystallites and the crystallinity were determined with wide-angle x-ray scattering (WAXS), whereas the nanoscale fibrillar structure of cellulose was characterized with small-angle x-ray and neutron scattering (SAXS and SANS). The properties determined with the small-angle scattering methods included specific surface areas and distances characteristic of the packing of cellulose microfibrils. Also other physical characterization methods, such as x-ray microtomography, infrared spectroscopy, and solid-state NMR were utilized in this work. In the analysis of the results, a comprehensive understanding of the structural changes throughout a range of length scales was aimed at. Pretreatment of birch sawdust by pressurized hot water extraction was observed to increase the crystal width of cellulose, as determined with WAXS, even though the cellulose crystallinity was slightly decreased. A denser packing of microfibrils caused by the removal of hemicelluloses and lignin in the extraction was evidenced by SAXS. This resulted in the opening of new pores between the microfibril bundles and an increase of the specific surface area. Enzymatic hydrolysis of microcrystalline cellulose (MCC) did not lead to differences in the average crystallinity or crystal size of the hydrolysis residues, which was explained to be caused by limitations due to the large size of the enzymes as compared to the pores inside the fibril aggregates. The SAXS intensities

  17. Structural changes of green roof growing substrate layer studied by X-ray CT

    Science.gov (United States)

    Jelinkova, Vladimira; Sacha, Jan; Dohnal, Michal; Snehota, Michal

    2017-04-01

    Increasing interest in green infrastructure linked with newly implemented legislation/rules/laws worldwide opens up research potential for field of soil hydrology. A better understanding of function of engineered soils involved in green infrastructure solutions such as green roofs or rain garden is needed. A soil layer is considered as a highly significant component of the aforesaid systems. In comparison with a natural soil, the engineered soil is assumed to be the more challenging case due to rapid structure changes early stages after its build-up. The green infrastructure efficiency depends on the physical and chemical properties of the soil, which are, in the case of engineered soils, a function of its initial composition and subsequent soil formation processes. The project presented in this paper is focused on fundamental processes in the relatively thick layer of engineered soil. The initial structure development, during which the pore geometry is altered by the growth of plant roots, water influx, solid particles translocation and other soil formation processes, is investigated with the help of noninvasive imaging technique  X-ray computed tomography. The soil development has been studied on undisturbed soil samples taken periodically from green roof test system during early stages of its life cycle. Two approaches and sample sizes were employed. In the first approach, undisturbed samples (volume of about 63 cm3) were taken each time from the test site and scanned by X-ray CT. In the second approach, samples (volume of about 630 cm3) were permanently installed at the test site and has been repeatedly removed to perform X-ray CT imaging. CT-derived macroporosity profiles reveal significant temporal changes of soil structure. Clogging of pores by fine particles and fissures development are two most significant changes that would affect the green roof system efficiency. This work has been supported by the Ministry of Education, Youth and Sports within

  18. Synthesis, X-ray crystallography, spectroscopy, electrochemistry, thermal and kinetic study of uranyl Schiff base complexes

    Czech Academy of Sciences Publication Activity Database

    Asadi, Z.; Golzard, F.; Eigner, Václav; Dušek, Michal

    2013-01-01

    Roč. 66, č. 20 (2013), s. 3629-3646 ISSN 0095-8972 R&D Projects: GA ČR(CZ) GAP204/11/0809 Institutional support: RVO:68378271 Keywords : X-ray crystallography * uranyl Schiff base complex * kinetics of thermal decomposition * cyclic voltammetry * kinetics and mechanism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.224, year: 2013

  19. Extended x-ray absorption fine structure (EXAFS): a novel probe for local structure of glassy solids

    International Nuclear Information System (INIS)

    Wong, J.

    1979-01-01

    The extended x-ray absorption fine structure (EXAFS) is the oscillation in the absorption coefficient extending a few hundred eVs on the high energy side of an x-ray absorption edge. This mode of spectroscopy has recently been realized to be a powerful tool in probing the local atomic structure of all states of matter, particularly with the advent of intense synchrotron radiation. More importantly is the unique ability of EXAFS to probe the structure and dynamics around individual atomic species in a multi-atomic system. In this paper, the physical processes associated with the EXAFS phenomenon will be discussed. Experimental results obtained at the Stanford Synchrotron Radiation Laboratory on some oxide and metallic glasses will be presented. The local structure in these materials are elucidated using a Fourier transform technique

  20. Nanoscale characterization of local structures and defects in photonic crystals using synchrotron-based transmission soft X-ray microscopy

    Science.gov (United States)

    Nho, Hyun Woo; Kalegowda, Yogesh; Shin, Hyun-Joon; Yoon, Tae Hyun

    2016-01-01

    For the structural characterization of the polystyrene (PS)-based photonic crystals (PCs), fast and direct imaging capabilities of full field transmission X-ray microscopy (TXM) were demonstrated at soft X-ray energy. PS-based PCs were prepared on an O2-plasma treated Si3N4 window and their local structures and defects were investigated using this label-free TXM technique with an image acquisition speed of ~10 sec/frame and marginal radiation damage. Micro-domains of face-centered cubic (FCC (111)) and hexagonal close-packed (HCP (0001)) structures were dominantly found in PS-based PCs, while point and line defects, FCC (100), and 12-fold symmetry structures were also identified as minor components. Additionally, in situ observation capability for hydrated samples and 3D tomographic reconstruction of TXM images were also demonstrated. This soft X-ray full field TXM technique with faster image acquisition speed, in situ observation, and 3D tomography capability can be complementally used with the other X-ray microscopic techniques (i.e., scanning transmission X-ray microscopy, STXM) as well as conventional characterization methods (e.g., electron microscopic and optical/fluorescence microscopic techniques) for clearer structure identification of self-assembled PCs and better understanding of the relationship between their structures and resultant optical properties. PMID:27087141

  1. The origin of luminescence from di[4-(4-diphenylaminophenyl)phenyl]sulfone (DAPSF), a blue light emitter: an X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) study.

    Science.gov (United States)

    Zhang, Duo; Zhang, Hui; Zhang, Xiaohong; Sham, Tsun-Kong; Hu, Yongfeng; Sun, Xuhui

    2016-03-07

    The electronic structure and optical properties of di[4-(4-diphenylaminophenyl)phenyl]sulfone (denoted as DAPSF), a highly efficient fluorophor, have been investigated using X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) spectroscopy at excitation energies across the C, N, O K-edges and the sulfur K-edge. The results indicate that the blue luminescence is mainly related to the sulfur functional group.

  2. Where Water is Oxidized to Dioxygen: Structure of the Photosynthetic Mn4Ca Cluster from X-ray Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Junko; Yano, Junko; Yachandra, Vittal K.

    2007-10-24

    Light-driven oxidation of water to dioxygen in plants, algae and cyanobacteria iscatalyzed within photosystem II (PS II) by a Mn4Ca cluster. Although the cluster has been studied by many different methods, the structure and the mechanism have remained elusive. X-ray absorption and emission spectroscopy and EXAFS studies have been particularly useful in probing the electronic and geometric structure, and the mechanism of the water oxidation reaction. Recent progress, reviewed here, includes polarized X-ray absorption spectroscopy measurements of PS II single crystals. Analysis of those results has constrained the Mn4Ca cluster geometry to a setof three similar high-resolution structures. The structure of the cluster from the present study is unlike either the 3.0 or 3.5 Angstrom-resolution X-ray structures or other previously proposed models. The differences between the models derived from X-rayspectroscopy and crystallography are predominantly because of damage to the Mn4Ca cluster by X-rays under the conditions used for structure determination by X-ray crystallography. X-ray spectroscopy studies are also used for studying the changes in the structure of the Mn4Ca catalytic center as it cycles through the five intermediate states known as the Si-states (i=0-4). The electronic structure of the Mn4Ca cluster has been studied more recently using resonant inelastic X-ray scattering spectroscopy (RIXS), in addition to the earlier X-ray absorption and emission spectroscopy methods. These studies are revealing that the assignment of formaloxidation states is overly simplistic. A more accurate description should consider the charge density on the Mn atoms that includes the covalency of the bonds and delocalization of the charge over the cluster. The geometric and electronic structure of the Mn4Ca cluster in the S-states derived from X-ray spectroscopy are leading to a detailed understanding of the mechanism of the O-O bond formation during the photosynthetic water

  3. Multi-scale characteristics of coal structure by x-ray computed tomography (x-ray CT), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP)

    Science.gov (United States)

    Cai, Ting-ting; Feng, Zeng-chao; Zhou, Dong

    2018-02-01

    It is of great benefit to study the material and structural heterogeneity of coal for better understanding the coalbed methane (CBM) storage and enrichment. In this paper, multi-scale X-ray computed tomography (CT), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP) at multi scales were conducted to thoroughly study the material distribution, heterogeneity, pore development, porosity and permeability of coal. It is suitable and reasonable to divide the testing samples into three structural categories by average density and heterogeneity degree, and the meso structure in the three categories accords with the morphology on SEM images. The pore size distribution and pore development of each subsample cannot be correspondingly related to their respective structure category or morphology due to different observation scales, while the macro pore size development, accumulated macro pore volume and macro pores porosity accord with the meso structure category and morphology information by CT and SEM at the same scale very well. Given the effect of macro pores on permeability and the contribution of micro pores to CBM storage capacity, reservoirs with developed micro pores and macro pores may be the most suitable coal reservoir for CBM exploitation.

  4. X-ray photoelectron spectra structure and chemical bonding in AmO2

    Directory of Open Access Journals (Sweden)

    Teterin Yury A.

    2015-01-01

    Full Text Available Quantitative analysis was done of the X-ray photoelectron spectra structure in the binding energy range of 0 eV to ~35 eV for americium dioxide (AmO2 valence electrons. The binding energies and structure of the core electronic shells (~35 eV-1250 eV, as well as the relativistic discrete variation calculation results for the Am63O216 and AmO8 (D4h cluster reflecting Am close environment in AmO2 were taken into account. The experimental data show that the many-body effects and the multiplet splitting contribute to the spectral structure much less than the effects of formation of the outer (0-~15 eV binding energy and the inner (~15 eV-~35 eV binding energy valence molecular orbitals. The filled Am 5f electronic states were shown to form in the AmO2 valence band. The Am 6p electrons participate in formation of both the inner and the outer valence molecular orbitals (bands. The filled Am 6p3/2 and the O 2s electronic shells were found to make the largest contributions to the formation of the inner valence molecular orbitals. Contributions of electrons from different molecular orbitals to the chemical bond in the AmO8 cluster were evaluated. Composition and sequence order of molecular orbitals in the binding energy range 0-~35 eV in AmO2 were established. The experimental and theoretical data allowed a quantitative scheme of molecular orbitals for AmO2, which is fundamental for both understanding the chemical bond nature in americium dioxide and the interpretation of other X-ray spectra of AmO2.

  5. X-ray absorption spectroscopy: EXAFS and XANES - A versatile tool to study the atomic and electronic structure of materials

    International Nuclear Information System (INIS)

    Alp, E.E.; Mini, S.M.; Ramanathan, M.

    1990-01-01

    X-ray absorption spectroscopy (XAS) had been an essential tool to gather spectroscopic information about atomic energy level structure in the early decades of this century. The correct interpretation of the oscillatory structure in the x-ray absorption cross-section above the absorption edge has transformed XAS from a spectroscopic tool to a structural technique. EXAFS (Extended X-ray Absorption Fine Structure) yields information about the interatomic distances, near neighbor coordination numbers, and lattice dynamics. XANES (X-ray Absorption Near Edge Structure), on the other hand, gives information about the valence state, energy bandwidth and bond angles. Today, there are about 50 experimental stations in various synchrotrons around the world dedicated to collecting x-ray absorption data from the bulk and surfaces of solids and liquids. In this chapter, they will give the basic principles of XAS, explain the information content of essentially two different aspects of the absorption process leading to EXAFS and XANES, and discuss the source and sample limitations

  6. Effect of Pressure on Valence and Structural Properties of YbFe2Ge2 Heavy Fermion Compound A Combined Inelastic X-ray Spectroscopy, X-ray Diffraction, and Theoretical Investigation

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ravhi S.; Svane, Axel; Vaitheeswaran; #8741; , Ganapathy; Kanchana, Venkatakrishnan; Antonio, Daniel; Cornelius, Andrew L.; Bauer, Eric D.; Xiao, Yuming; Chow, Paul (Aarhus); (CIW); (Hyderabad - India); (IIT-India); (LANL); (UNLV)

    2016-06-03

    The crystal structure and the Yb valence of the YbFe2Ge2 heavy fermion compound was measured at room temperature and under high pressures using high-pressure powder X-ray diffraction and X-ray absorption spectroscopy via both partial fluorescence yield and resonant inelastic X-ray emission techniques. Furthermore, the measurements are complemented by first-principles density functional theoretical calculations using the self-interaction corrected local spin density approximation investigating in particular the magnetic structure and the Yb valence. While the ThCr2Si2-type tetragonal (I4/mmm) structure is stable up to 53 GPa, the X-ray emission results show an increase of the Yb valence from v = 2.72(2) at ambient pressure to v = 2.93(3) at ~9 GPa, where at low temperature a pressure-induced quantum critical state was reported.

  7. Probing Photoinduced Structural Phase Transitions by Fast or Ultra-Fast Time-Resolved X-Ray Diffraction

    Science.gov (United States)

    Cailleau, Hervé Collet, Eric; Buron-Le Cointe, Marylise; Lemée-Cailleau, Marie-Hélène Koshihara, Shin-Ya

    A new frontier in the field of structural science is the emergence of the fast and ultra-fast X-ray science. Recent developments in time-resolved X-ray diffraction promise direct access to the dynamics of electronic, atomic and molecular motions in condensed matter triggered by a pulsed laser irradiation, i.e. to record "molecular movies" during the transformation of matter initiated by light pulse. These laser pump and X-ray probe techniques now provide an outstanding opportunity for the direct observation of a photoinduced structural phase transition as it takes place. The use of X-ray short-pulse of about 100ps around third-generation synchrotron sources allows structural investigations of fast photoinduced processes. Other new X-ray sources, such as laser-produced plasma ones, generate ultra-short pulses down to 100 fs. This opens the way to femtosecond X-ray crystallography, but with rather low X-ray intensities and more limited experimental possibilities at present. However this new ultra-fast science rapidly progresses around these sources and new large-scale projects exist. It is the aim of this contribution to overview the state of art and the perspectives of fast and ultra-fast X-ray scattering techniques to study photoinduced phase transitions (here, the word ultra-fast is used for sub-picosecond time resolution). In particular we would like to largely present the contribution of crystallographic methods in comparison with optical methods, such as pump-probe reflectivity measurements, the reader being not necessary familiar with X-ray scattering. Thus we want to present which type of physical information can be obtained from the positions of the Bragg peaks, their intensity and their shape, as well as from the diffuse scattering beyond Bragg peaks. An important physical feature is to take into consideration the difference in nature between a photoinduced phase transition and conventional homogeneous photoinduced chemical or biochemical processes where

  8. Grazing angle X-ray fluorescence from periodic structures on silicon and silica surfaces

    International Nuclear Information System (INIS)

    Nowak, S.H.; Banaś, D.; Błchucki, W.; Cao, W.; Dousse, J.-Cl.; Hönicke, P.; Hoszowska, J.; Jabłoński, Ł.; Kayser, Y.; Kubala-Kukuś, A.; Pajek, M.; Reinhardt, F.; Savu, A.V.; Szlachetko, J.

    2014-01-01

    Various 3-dimensional nano-scaled periodic structures with different configurations and periods deposited on the surface of silicon and silica substrates were investigated by means of the grazing incidence and grazing emission X-ray fluorescence techniques. Apart from the characteristics which are typical for particle- and layer-like samples, the measured angular intensity profiles show additional periodicity-related features. The latter could be explained by a novel theoretical approach based on simple geometrical optics (GO) considerations. The new GO-based calculations were found to yield results in good agreement with experiment, also in cases where other theoretical approaches are not valid, e.g., periodic particle distributions with an increased surface coverage

  9. Computed microtomography and X-ray fluorescence analysis for comprehensive analysis of structural changes in bone.

    Science.gov (United States)

    Buzmakov, Alexey; Chukalina, Marina; Nikolaev, Dmitry; Schaefer, Gerald; Gulimova, Victoria; Saveliev, Sergey; Tereschenko, Elena; Seregin, Alexey; Senin, Roman; Prun, Victor; Zolotov, Denis; Asadchikov, Victor

    2013-01-01

    This paper presents the results of a comprehensive analysis of structural changes in the caudal vertebrae of Turner's thick-toed geckos by computer microtomography and X-ray fluorescence analysis. We present algorithms used for the reconstruction of tomographic images which allow to work with high noise level projections that represent typical conditions dictated by the nature of the samples. Reptiles, due to their ruggedness, small size, belonging to the amniote and a number of other valuable features, are an attractive model object for long-orbital experiments on unmanned spacecraft. Issues of possible changes in their bone tissue under the influence of spaceflight are the subject of discussions between biologists from different laboratories around the world.

  10. X-ray diffraction and molecular-dynamics studies: Structural analysis of phases in diglyceride monolayers

    DEFF Research Database (Denmark)

    Peters, Günther H.J.; Larsen, Niels Bent; Bjørnholm, T.

    1998-01-01

    We report a detailed structural analysis of the phases of 1,2-sn-dipalmitoylglycerol Langmuir monolayers at room temperature. Pressure-induced transitions have been investigated by combination of molecular-dynamics simulations and grazing-incidence x-ray diffraction (XRD). The diglyceride film...... undergoes two phase transitions occurring at 38.3 and 39.8 Angstrom(2)/molecule. Simulation indicates that the first transition involves a reorientation of the headgroups while simulation and XRD show that in the second transition the order parameter is the tilt angle of the alkyl chains. A methodology......; At the lowest pressure the tilt angle reaches approximate to 14 degrees in a direction close to a nearest neighbor direction. Both arrangements of the alkyl chains are confirmed by XRD. For higher order and fractional order Bragg peaks, simulations predict higher intensities than observed with XRD. This may...

  11. Structural phase transition in lanthanum gallate as studied by Raman and X-ray diffraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dhak, P.; Pramanik, P. [Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India); Bhattacharya, S.; Roy, Anushree [Department of Physics, Indian Institute of Technology, Kharagpur 721302 (India); Achary, S.N.; Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2011-08-15

    Lanthanum gallate (LaGaO{sub 3}) is known to undergo orthorhombic to rhombohedral first order phase transition at 150 C. In this article we have shown that by introducing 2% La deficiency in the system, coexistence of above two phases can be obtained at lower temperature and a complete phase transition occurs at 200 C. The evolution of structural parameters of the system with temperature is reported from X-ray diffraction measurements and Rietveld analysis of the diffraction patterns. The change in local octahedral distortion due to 2% La deficiency is revealed through the shift in the phonon modes of GaO{sub 6} octahedra, in both orthorhombic and rhombohedral phase. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Study of thermal degradation of organic light emitting device structures by X-ray scattering

    International Nuclear Information System (INIS)

    Lee, Young-Joo; Lee, Heeju; Byun, Youngsuk; Song, Sanghoon; Kim, Je-Eun; Eom, Daeyong; Cha, Wonsuk; Park, Seong-Sik; Kim, Jinwoo; Kim, Hyunjung

    2007-01-01

    We report the process of thermal degradation of organic light emitting devices (OLEDs) having multilayered structure of [LiF/tris-(8-hydroxyquinoline) aluminum(Alq 3 )/N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB)/copper phthalocyanine (CuPc)/indium tin oxide (ITO)/SiO 2 on a glass] by synchrotron X-ray scattering. The results show that the thermally induced degradation process of OLED multilayers has undergone several evolutions due to thermal expansion of NPB, intermixing between NPB, Alq 3 , and LiF layers, dewetting of NPB on CuPc, and crystallization of NPB and Alq 3 depending on the annealing temperature. The crystallization of NPB appears at 180 deg. C, much higher temperature than the glass transition temperature (T g = 96 deg. C) of NPB. The results are also compared with the findings from the atomic force microscope (AFM) images

  13. Determination of collagen fibril structure and orientation in connective tissues by X-ray diffraction

    Science.gov (United States)

    Wilkinson, S. J.; Hukins, D. W. L.

    1999-08-01

    Elastic scattering of X-rays can provide the following information on the fibrous protein collagen: its molecular structure, the axial arrangement of rod-like collagen molecules in a fibril, the lateral arrangement of molecules within a fibril, and the orientation of fibrils within a biological tissue. The first part of the paper reviews the principles involved in deducing this information. The second part describes a new computer program for measuring the equatorial intensity distribution, that provides information on the lateral arrangement of molecules within a fibril, and the angular distribution of the equatorial peaks that provides information on the orientation of fibrils. Orientation of fibrils within a tissue is quantified by the orientation distribution function, g( φ), which represents the probability of finding a fibril oriented between φ and φ+ δφ. The application of the program is illustrated by measurement of g( φ) for the collagen fibrils in demineralised cortical bone from cow tibia.

  14. X-ray diffractometric study on the near-surface layer structure in parallel glancing rays

    International Nuclear Information System (INIS)

    Shtypulyak, N.I.; Yakimov, I.I.; Litvintsev, V.V.

    1988-01-01

    X-ray diffraction method is suggested to use to investigate thin films and near-surface layers under the conditions of total external reflection (TER) and in the geometry of parallel glancing rays. Experimental realization of the method using the DRON-30 diffractometer is described. Calculation for the required width of the aperture of Soller slot system is presented. The described diffraction scheme is used to investigate thin film crystal structure at glancing angles in the range from TER up to 8-10 deg. The thickness of the investigated layer in this case changes from 2.5-8 nm up to 10 3 nm. The suggested diffraction method in parallel glancing rays is especially important when investigating the films with thickness lower than 1000-2000A

  15. Redetermination of the borax structure from laboratory X-ray data at 145 K.

    Science.gov (United States)

    Gainsford, Graeme J; Kemmitt, Tim; Higham, Caleb

    2008-04-23

    THE TITLE COMPOUND, SODIUM TETRABORATE DECAHYDRATE (MINERAL NAME: borax), Na(2)[B(4)O(5)(OH)(4)]·8H(2)O, has been studied previously using X-ray [Morimoto (1956). Miner. J.2, 1-18] and neutron [Levy & Lisensky (1978). Acta Cryst. B34, 3502-3510] diffraction data. The structure contains tetra-borate anions [B(4)O(5)(OH)(4)](2-) with twofold rotation symmetry, which form hydrogen-bonded chains, and [Na(H(2)O)(6)] octa-hedra that form zigzag chains [Na(H(2)O)(4/2)(H(2)O)(2/1)]. The O-H bond distances obtained from the present redetermination at 145 K are shorter than those in the neutron study by an average of 0.127 (19) Å.

  16. Redetermination of the borax structure from laboratory X-ray data at 145 K

    Directory of Open Access Journals (Sweden)

    Caleb Higham

    2008-05-01

    Full Text Available The title compound, sodium tetraborate decahydrate (mineral name: borax, Na2[B4O5(OH4]·8H2O, has been studied previously using X-ray [Morimoto (1956. Miner. J. 2, 1–18] and neutron [Levy & Lisensky (1978. Acta Cryst. B34, 3502–3510] diffraction data. The structure contains tetraborate anions [B4O5(OH4]2− with twofold rotation symmetry, which form hydrogen-bonded chains, and [Na(H2O6] octahedra that form zigzag chains [Na(H2O4/2(H2O2/1]. The O—H bond distances obtained from the present redetermination at 145 K are shorter than those in the neutron study by an average of 0.127 (19 Å.

  17. Structural anisotropy in amorphous SnO2 film probed by X-ray absorption spectroscopy

    Science.gov (United States)

    Zhu, Q.; Ma, Q.; Buchholz, D. B.; Chang, R. P. H.; Bedzyk, M. J.; Mason, T. O.

    2013-07-01

    Polarization-dependent X-ray absorption measurements reveal the existence of structural anisotropy in amorphous (a-) SnO2 film. The anisotropy is readily seen for the second neighbor interaction whose magnitude differs along three measured directions. The differences can be well accounted for by 10%-20% variation in the Debye-Waller factor. Instead of a single Gaussian distribution found in crystalline SnO2, the Sn-O bond distribution is bimodal in a-SnO2 whose separation shows a weak angular dependence. The oxygen vacancies, existing in the a-SnO2 film in the order of 1021 cm-3, distribute preferentially along the film surface direction.

  18. Some applications of nanometer scale structures for current and future X-ray space research

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Abdali, S; Frederiksen, P K

    1994-01-01

    Nanometer scale structures such as multilayers, gratings and natural crystals are playing an increasing role in spectroscopic applications for X-ray astrophysics. A few examples are briefly described as an introduction to current and planned applications pursued at the Danish Space Research...... Institute in collaboration with the FOM Institute for Plasma Physics, Nieuwegein, the Max-Planck-Institut für Extraterrestrische Physik, Aussenstelle Berlin, the Space Research Institute, Russian Academy of Sciences, the Smithsonian Astrophysical Observatory, Ovonics Synthetic Materials Company and Lawrence...... Livermore National Laboratory. These examples include : 1. the application of multilayered Si crystals for simultaneous spectroscopy in two energy bands one centred around the SK-emission near 2.45 keV and the other below the CK absorption edge at 0.284 keV; 2. the use of in-depth graded period multilayer...

  19. X-ray Crystal Structures Elucidate the Nucleotidyl Transfer Reaction of Transcript Initiation Using Two Nucleotides

    Energy Technology Data Exchange (ETDEWEB)

    M Gleghorn; E Davydova; R Basu; L Rothman-Denes; K Murakami

    2011-12-31

    We have determined the X-ray crystal structures of the pre- and postcatalytic forms of the initiation complex of bacteriophage N4 RNA polymerase that provide the complete set of atomic images depicting the process of transcript initiation by a single-subunit RNA polymerase. As observed during T7 RNA polymerase transcript elongation, substrate loading for the initiation process also drives a conformational change of the O helix, but only the correct base pairing between the +2 substrate and DNA base is able to complete the O-helix conformational transition. Substrate binding also facilitates catalytic metal binding that leads to alignment of the reactive groups of substrates for the nucleotidyl transfer reaction. Although all nucleic acid polymerases use two divalent metals for catalysis, they differ in the requirements and the timing of binding of each metal. In the case of bacteriophage RNA polymerase, we propose that catalytic metal binding is the last step before the nucleotidyl transfer reaction.

  20. Laboratory-based recording of holographic fine structure in X-ray absorption anisotropy using polycapillary optics

    Energy Technology Data Exchange (ETDEWEB)

    Dabrowski, K.M. [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Korecki, P., E-mail: pawel.korecki@uj.edu.pl [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Holographic fine structures in X-ray absorption recorded using a tabletop setup. Black-Right-Pointing-Pointer Setup based on polycapillary collimating optics and an HOPG crystal. Black-Right-Pointing-Pointer Demonstration of element sensitivity by detection of X-ray fluorescence. Black-Right-Pointing-Pointer Potential of laboratory-based experiments for heavily doped crystals and thin films. - Abstract: A tabletop setup composed of a collimating polycapillary optics and a highly oriented pyrolytic graphite monochromator (HOPG) was characterized and used for recording two-dimensional maps of X-ray absorption anisotropy (XAA). XAA originates from interference of X-rays directly inside the sample. Depending on experimental conditions, fine structures in XAA can be interpreted in terms of X-ray holograms or X-ray standing waves and can be used for an element selective atomic-resolved structural analysis. The implementation of polycapillary optics resulted in a two-order of magnitude gain in the radiant intensity (photons/s/solid angle) as compared to a system without optics and enabled efficient recording of XAA with a resolution of 0.15 Degree-Sign for Mo K{alpha} radiation. Element sensitivity was demonstrated by acquisition of distinct XAA signals for Ga and As atoms in a GaAs (1 1 1) wafer by using X-ray fluorescence as a secondary signal. These results indicate the possibility of performing laboratory-based XAA experiments for heavily doped single crystals or thin films. So far, because of the weak holographic modulation of XAA, such experiments could be only performed using synchrotron radiation.

  1. X-ray holographic imaging of magnetic order in meander domain structures

    Directory of Open Access Journals (Sweden)

    Jaouen Nicolas

    2013-01-01

    Full Text Available We performed x-ray holography experiments using synchrotron radiation. By analyzing the scattering of coherent circularly polarized x-rays tuned at the Co-2p resonance, we imaged perpendicular magnetic domains in a Co/Pd multilayer. We compare results obtained for continuous and laterally confined films.

  2. Simulation of x-rays in refractive structure by the Monte Carlo method using the supercomputer SKIF

    International Nuclear Information System (INIS)

    Yaskevich, Yu.R.; Kravchenko, O.I.; Soroka, I.I.; Chembrovskij, A.G.; Kolesnik, A.S.; Serikova, N.V.; Petrov, P.V.; Kol'chevskij, N.N.

    2013-01-01

    Software 'Xray-SKIF' for the simulation of the X-rays in refractive structures by the Monte-Carlo method using the supercomputer SKIF BSU are developed. The program generates a large number of rays propagated from a source to the refractive structure. The ray trajectory under assumption of geometrical optics is calculated. Absorption is calculated for each ray inside of refractive structure. Dynamic arrays are used for results of calculation rays parameters, its restore the X-ray field distributions very fast at different position of detector. It was found that increasing the number of processors leads to proportional decreasing of calculation time: simulation of 10 8 X-rays using supercomputer with the number of processors from 1 to 30 run-times equal 3 hours and 6 minutes, respectively. 10 9 X-rays are calculated by software 'Xray-SKIF' which allows to reconstruct the X-ray field after refractive structure with a special resolution of 1 micron. (authors)

  3. Evaluation of pore structures and cracking in cement paste exposed to elevated temperatures by X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kwang Yeom, E-mail: kimky@kict.re.kr [Korea Institute of Construction Technology, 283 Goyangdae-ro, Ilsanseo-gu, Goyang 411-712 (Korea, Republic of); Yun, Tae Sup, E-mail: taesup@yonsei.ac.kr [School of Civil and Environmental Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Park, Kwang Pil, E-mail: bamtol97@kict.re.kr [Korea Institute of Construction Technology, 283 Goyangdae-ro, Ilsanseo-gu, Goyang 411-712 (Korea, Republic of)

    2013-08-15

    When cement-based materials are exposed to the high temperatures induced by fire, which can rapidly cause temperatures of over 1000 °C, the changes in pore structure and density prevail. In the present study, mortar specimens were subjected to a series of increasing temperatures to explore the temperature-dependent evolution of internal pore structure. High-performance X-ray computed tomography (CT) was used to observe the evolution of temperature-induced discontinuities at the sub-millimeter level. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to investigate the cause of physical changes in the heated mortar specimens. Results exhibit the changes in pore structure caused by elevated temperatures, and thermally induced fractures. We discuss the progressive formation of thermally induced fracture networks, which is a prerequisite for spalling failure of cement-based materials by fire, based on visual observations of the 3D internal structures revealed by X-ray CT.

  4. Evaluation of pore structures and cracking in cement paste exposed to elevated temperatures by X-ray computed tomography

    International Nuclear Information System (INIS)

    Kim, Kwang Yeom; Yun, Tae Sup; Park, Kwang Pil

    2013-01-01

    When cement-based materials are exposed to the high temperatures induced by fire, which can rapidly cause temperatures of over 1000 °C, the changes in pore structure and density prevail. In the present study, mortar specimens were subjected to a series of increasing temperatures to explore the temperature-dependent evolution of internal pore structure. High-performance X-ray computed tomography (CT) was used to observe the evolution of temperature-induced discontinuities at the sub-millimeter level. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to investigate the cause of physical changes in the heated mortar specimens. Results exhibit the changes in pore structure caused by elevated temperatures, and thermally induced fractures. We discuss the progressive formation of thermally induced fracture networks, which is a prerequisite for spalling failure of cement-based materials by fire, based on visual observations of the 3D internal structures revealed by X-ray CT

  5. X-Ray Absorption Near-Edge Structure (XANES) of Calcium L3,2 Edges of Various Calcium Compounds and X-Ray Excited Optical Luminescence (XEOL) Studies of Luminescent Calcium Compounds

    International Nuclear Information System (INIS)

    Ko, J. Y. Peter; Zhou Xingtai; Sham, T.-K.; Heigl, Franziskus; Regier, Tom; Blyth, Robert

    2007-01-01

    X-ray absorption at calcium L3,2 edges of various calcium compounds were measured using a high resolution Spherical Grating Monochromator (SGM) at the Canadian Light Source (CLS). We observe that each compound has its unique fine structure of L3,2 edges. This uniqueness is due to differences in local structure of compounds. We also performed (X-ray Excited Optical Luminescence) XEOL of selected luminescent calcium compounds to investigate their optical properties. XEOL is a photon-in-photon-out technique in which the optical luminescence that is excited by tunable x-rays from a synchrotron light source is monitored. Depending on excitation energy of the x-ray, relative intensities of luminescence peaks vary. Recent findings of the results will be presented here

  6. Higher order structure analysis of nano-materials by spectral reflectance of laser-plasma soft x-ray

    International Nuclear Information System (INIS)

    Azuma, Hirozumi; Takeichi, Akihiro; Noda, Shoji

    1995-01-01

    We have proposed a new experimental arrangement to measure spectral reflectance of nano-materials for analyzing higher order structure with laser-plasma soft x-rays. Structure modification of annealed Mo/Si multilayers and a nylon-6/clay hybrid with poor periodicity was investigated. The measurement of the spectral reflectance of soft x-rays from laser-produced plasma was found to be a useful method for the structure analysis of nano-materials, especially those of rather poor periodicity

  7. Structural investigations of LiFePO4 electrodes and in situ studies by Fe X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Deb, Aniruddha; Bergmann, Uwe; Cramer, S.P.; Cairns, Elton J.

    2005-01-01

    Fe K-edge X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) have been performed on electrodes containing LiFePO 4 to determine the local atomic and electronic structure and their stability with electrochemical cycling. A versatile electrochemical in situ cell has been constructed for long-term soft and hard X-ray experiments for the structural investigation on battery electrodes during the lithium-insertion/extraction processes. The device is used here for an X-ray absorption spectroscopic study of lithium insertion/extraction in a LiFePO 4 electrode, where the electrode contained about 7.7 mg of LiFePO 4 on a 20 μm thick Al-foil. Fe K-edge X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) have been performed on this electrode to determine the local atomic and electronic structure and their stability with electrochemical cycling. The initial state (LiFePO 4 ) showed iron to be in the Fe 2+ state corresponding to the initial state (0.0 mAh) of the cell, whereas in the delithiated state (FePO 4 ) iron was found to be in the Fe 3+ state corresponding to the final charged state (3 mAh). XANES region of the XAS spectra revealed a high spin configuration for the two states (Fe (II), d 6 and Fe (III), d 5 ). The results confirm that the olivine structure of the LiFePO 4 and FePO 4 is retained by the electrodes in agreement with the XRD observations reported previously. These results confirm that LiFePO 4 cathode material retains good structural short-range order leading to superior cycling capability

  8. Structure solution from powder neutron and x-ray diffraction data: getting the best of both worlds

    International Nuclear Information System (INIS)

    Hunter, B.A.

    2000-01-01

    Full text: Powder diffraction methods have traditionally been used in three main areas: phase identification and quantification, lattice parameter determination and structure refinement. Until recently structure solution has been the almost exclusive domain of single crystal diffraction methods, predominantly using x-rays. The increasing use of synchrotron and neutron sources, and the unrelenting advances in computing hardware and software means that powder methods are challenging single crystal methods as a practical method for structure solution, especially when single crystal method can not be applied. It is known that structural refinements from a known starting structure using combined X-ray and neutron data sets are capable of providing highly accurate structures. Likewise, using combined x-ray and neutron powder diffraction data in the structure solution process should also be a powerful technique, although to date no one is pursuing this methodology. This paper present examples of solutions to the problem. Namely we are using high resolution powder X-ray and neutron methods to solve the structures of molecular materials and minerals, then refining the structures using both sets of data. In this way we exploit the advantages of both methods while minimising the disadvantages. We present our solution for a small amino acid structure, a metalorganic and a mineral structure

  9. Local structure of metallic chips examined by X-ray microdiffraction

    International Nuclear Information System (INIS)

    Saksl, K.; Rokicki, P.; Siemers, C.; Ostroushko, D.; Bednarčík, J.; Rütt, U.

    2013-01-01

    Highlights: •We present a detailed microstructure and phase analysis of chips produced by cutting. •3D analysis proved mixed nature of shear bands propagation to the material. •We examine phase composition of the chips by focused X-ray beam. •Crystallites in segment and shear band change their orientation up to 10°. -- Abstract: Nickel-base alloys are used in high-temperature applications whenever steels or titanium alloys cannot be applied anymore. This class of alloys is furthermore used in low-temperature applications in the oil or gas industry in case the corrosion resistance of stainless steels in related liquid media is not sufficient and titanium alloys would be too expensive. Nickel-base alloys, however, due to their high strength and toughness can be machined only at low cutting speeds as otherwise poor surface quality and enhanced tool wear is observed. From all aspects influencing the machinability, the chip formation mechanism is the key factor and only a thorough understanding of this mechanism can lead to an optimisation of the cutting process. In the current study, a detailed microstructure and phase analysis of Alloy 625 chips produced in an orthogonal cutting process at conventional cutting speeds is presented. Utilising hard monochromatic X-rays focused down to micrometre size, microstructural differences between distinct structural units of the chips, namely, the segments and shear bands, are investigated. Scanning cross sections of the chips with this small beam allowed us to determine misorientation between the segments and shear bands crystal lattices which as we found are not changing abruptly but continuously, with an absolute difference up to 10°

  10. Interaction of femtosecond X-ray pulses with periodical multilayer structures

    International Nuclear Information System (INIS)

    Ksenzov, Dmitry

    2010-01-01

    The VUV Free Electron Laser FLASH operates in soft X-ray range and produces high-intensive pulse trains with few tens femtoseconds duration. The transversely fully coherent beam will open new experiments in solid state physics which can not be studied with present radiation sources. The study of the time dependent response of the multilayer to the X-ray pulse can provide insights into the process of interaction of highly intense FEL radiation with matter. To test the influence of electron excitation on the optical properties of boron carbide, the refractive index of B 4 C was measured near B K-edge by energy-resolved photon-in-photon-out method probing a Bragg reflection from periodical multilayers. The measured data clearly show that the variation of the fine structure of the Kabsorption edges due to the chemical nature of the absorber element. The knowledge obtained from experiments with continuous radiation was used to design the respective experiments with pulse from the FEL. In my thesis, it is proposed that the geometrical setup, where the incident pulse arrives from the FEL under the angle close to the 1st order ML Bragg peak, provides the most valuable information. Preliminary simulation considering form factors of neutral and ionized boron showed that due to ionization, pronounced changes in the reflectivity curve are expected. The proposed scheme can be the powerful tool to study the various processes within the electronic subsystem of the FEL pulse interaction with matter. This type of investigations gives a deep understanding of the nature of the electronic excitation and the recombination at the femtosecond scale. (orig.)

  11. Interaction of femtosecond X-ray pulses with periodical multilayer structures

    Energy Technology Data Exchange (ETDEWEB)

    Ksenzov, Dmitry

    2010-07-01

    The VUV Free Electron Laser FLASH operates in soft X-ray range and produces high-intensive pulse trains with few tens femtoseconds duration. The transversely fully coherent beam will open new experiments in solid state physics which can not be studied with present radiation sources. The study of the time dependent response of the multilayer to the X-ray pulse can provide insights into the process of interaction of highly intense FEL radiation with matter. To test the influence of electron excitation on the optical properties of boron carbide, the refractive index of B{sub 4}C was measured near B K-edge by energy-resolved photon-in-photon-out method probing a Bragg reflection from periodical multilayers. The measured data clearly show that the variation of the fine structure of the Kabsorption edges due to the chemical nature of the absorber element. The knowledge obtained from experiments with continuous radiation was used to design the respective experiments with pulse from the FEL. In my thesis, it is proposed that the geometrical setup, where the incident pulse arrives from the FEL under the angle close to the 1st order ML Bragg peak, provides the most valuable information. Preliminary simulation considering form factors of neutral and ionized boron showed that due to ionization, pronounced changes in the reflectivity curve are expected. The proposed scheme can be the powerful tool to study the various processes within the electronic subsystem of the FEL pulse interaction with matter. This type of investigations gives a deep understanding of the nature of the electronic excitation and the recombination at the femtosecond scale. (orig.)

  12. Local structure of metallic chips examined by X-ray microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Saksl, K., E-mail: ksaksl@imr.saske.sk [Institut of Materials Research, Slovak Academy of Sciences, Watsonova 47, 040 01 Košice (Slovakia); Rokicki, P. [The Faculty of Mechanical Engineering and Aeronautics, Rzeszow University of Technology, Al. Powstancow Warszawy 12, 35-959 Rzeszow (Poland); Siemers, C. [Institut fuer Werkstoffe, Technische Universitaet Braunschweig, Langer Kamp 8, 38106 Braunschweig (Germany); Ostroushko, D. [Faculty of Metallurgy and Materials Engineering, VŠB – Technical University of Ostrava, 17.listopadu 15, 708 33 Ostrava (Czech Republic); Bednarčík, J.; Rütt, U. [HASYLAB at DESY, Notkestr. 85, D-22607 Hamburg (Germany)

    2013-12-25

    Highlights: •We present a detailed microstructure and phase analysis of chips produced by cutting. •3D analysis proved mixed nature of shear bands propagation to the material. •We examine phase composition of the chips by focused X-ray beam. •Crystallites in segment and shear band change their orientation up to 10°. -- Abstract: Nickel-base alloys are used in high-temperature applications whenever steels or titanium alloys cannot be applied anymore. This class of alloys is furthermore used in low-temperature applications in the oil or gas industry in case the corrosion resistance of stainless steels in related liquid media is not sufficient and titanium alloys would be too expensive. Nickel-base alloys, however, due to their high strength and toughness can be machined only at low cutting speeds as otherwise poor surface quality and enhanced tool wear is observed. From all aspects influencing the machinability, the chip formation mechanism is the key factor and only a thorough understanding of this mechanism can lead to an optimisation of the cutting process. In the current study, a detailed microstructure and phase analysis of Alloy 625 chips produced in an orthogonal cutting process at conventional cutting speeds is presented. Utilising hard monochromatic X-rays focused down to micrometre size, microstructural differences between distinct structural units of the chips, namely, the segments and shear bands, are investigated. Scanning cross sections of the chips with this small beam allowed us to determine misorientation between the segments and shear bands crystal lattices which as we found are not changing abruptly but continuously, with an absolute difference up to 10°.

  13. Potential application of microfocus X-ray techniques for quantitative analysis of bone structure

    International Nuclear Information System (INIS)

    Takahashi, Kenta

    2006-01-01

    With the progress of micro-focused X-ray computed tomography (micro-CT), it has become possible to evaluate the bone structure quantitatively and three-dimensionally. The advantages of micro-CT are that sample preparations are not required and that it provides not only two-dimensional parameters but also three-dimensional stereological indices. This study was carried out to evaluate the potential application of the micro-focus X-ray techniques for quantitative analysis of the new bone produced inside of a hollow chamber of the experimental titanium miniature implant. Twenty-five male wistar rats (9-weeks of age) received experimental titanium miniature implant that had a hollow chamber inside in the left side of the femur. The rats were sacrificed, then the femurs were excised at 4 weeks or 8 weeks after implantation. Micro-CT analysis was performed on the femur samples and the volume of the new bone induced in the hollow chamber of implant was calculated. Percentages of new bone area on the undecalcified histological slides were also measured, linear regression analysis was carried out. In order to evaluate the correlation between pixel numbers of undecalcified slide specimen and pixel numbers of micro-CT image. New bone formation occurred in experimental titanium miniature implant with a hollow chamber. The volume of new bone was measured by micro CT and the area percentage of new bone area against hollow chamber was calculated on the undecalcified slide. Linear regression analysis showed a high correlation between the pixel numbers of undecalcified slide specimen and pixel numbers of micro-CT image. Consequently, the new bone produced inside of the hollow chamber of the experimental titanium miniature implant could be quantified as three-dimensional stereological by micro-CT and its precision was supported by the high correlation between the measurement by micro-CT and conservative two-dimensional measurement of histological slide. (author)

  14. Selenium Derivatization of Nucleic Acids for Phase and Structure Determination in Nucleic Acid X-ray Crystallography

    Directory of Open Access Journals (Sweden)

    Zhen Huang

    2008-03-01

    Full Text Available Selenium derivatization (via selenomethionine of proteins for crystal structure determination via MAD phasing has revolutionized protein X-ray crystallography. It is estimated that over two thirds of all new crystal structures of proteins have been determined via Se-Met derivatization. Similarly, selenium functionalities have also been successfully incorporated into nucleic acids to facilitate their structure studies and it has been proved that this Se-derivatization has advantages over halogen strategy, which was usually used as a traditional method in this field. This review reports the development of site-specific selenium derivatization of nucleic acids for phase determination since the year of 2001 (mainly focus on the 2’-position of the ribose. All the synthesis of 2’-SeMe modified phosphoramidite building blocks (U, C, T, A, G and the according oligonucleotides are included. In addition, several structures of selenium contained nucleic acid are also described in this paper.

  15. X-ray structure of imidazolonepropionase from Agrobacterium tumefaciens at 1.87 Å resolution

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Rajiv; Kumaran, Desigan; Burley, Stephen K.; Swaminathan, Subramanyam (SGX); (BNL)

    2010-01-12

    Histidine degradation in Agrobacterium tumefaciens involves four enzymes, including histidase (EC 4.3.1.3), urocanase (EC 4.2.1.49), imidazolonepropionase (EC 3.5.2.7), and N-formylglutamate amidohydrolase (EC 3.5.3.8). The third enzyme of the pathway, imidazolone-propionase, a 45.6 kDa protein, catalyzes conversion of imidazolone-5-propanoate to N-forminio-L-glutamate. Initial studies of the role of imidazolonepropionase in histidine degradation were published in 1953. Subsequent publications have been limited to enzyme kinetics, crystallization, and a recently reported structure determination. The imidazolonepropionases are members of metallodepenent-hydrolases (or amidohydroase) superfamily, which includs ureases, adenosine deaminases, phosphotriesterases, dihydroorotases, allantoinases, hydantoinases, adenine and cytosine deaminases, imidazolonepropionases, aryldial-kylphosphatases, chlorohydrolases, and formylmethanofuran dehydroases. Proteins belonging to this large group share a common three-dimensional structural motif (an eightfold {alpha}/{beta} or TIM barrel) with similar active sites. Most superfamily members also share a conserved metal binding site, involving four histidine residues and one aspartic acid. Imidazolonepropionase is one of the targets selected for X-ray crystallpgrahpic structure determination by the New York Structural GenomiX Research Consortium (NYSGXRC) Target ID: 9252b to correlate the structure function relationship of poorly studied by important enzyme. Here they report the crystal structure of imidazolonepropionase from Agrobacterium tumefaciens determined at 1.87 {angstrom} resolution.

  16. Modeling the structure of RNA molecules with small-angle X-ray scattering data.

    Directory of Open Access Journals (Sweden)

    Michal Jan Gajda

    Full Text Available We propose a novel fragment assembly method for low-resolution modeling of RNA and show how it may be used along with small-angle X-ray solution scattering (SAXS data to model low-resolution structures of particles having as many as 12 independent secondary structure elements. We assessed this model-building procedure by using both artificial data on a previously proposed benchmark and publicly available data. With the artificial data, SAXS-guided models show better similarity to native structures than ROSETTA decoys. The publicly available data showed that SAXS-guided models can be used to reinterpret RNA structures previously deposited in the Protein Data Bank. Our approach allows for fast and efficient building of de novo models of RNA using approximate secondary structures that can be readily obtained from existing bioinformatic approaches. We also offer a rigorous assessment of the resolving power of SAXS in the case of small RNA structures, along with a small multimetric benchmark of the proposed method.

  17. Structural evaluation of an amyloid fibril model using small-angle x-ray scattering

    Science.gov (United States)

    Dahal, Eshan; Choi, Mina; Alam, Nadia; Bhirde, Ashwinkumar A.; Beaucage, Serge L.; Badano, Aldo

    2017-08-01

    Amyloid fibrils are highly structured protein aggregates associated with a wide range of diseases including Alzheimer’s and Parkinson’s. We report a structural investigation of an amyloid fibril model prepared from a commonly used plasma protein (bovine serum albumin (BSA)) using small-angle x-ray scattering (SAXS) technique. As a reference, the size estimates from SAXS are compared to dynamic light scattering (DLS) data and the presence of amyloid-like fibrils is confirmed using Congo red absorbance assay. Our SAXS results consistently show the structural transformation of BSA from spheroid to rod-like elongated structures during the fibril formation process. We observe the elongation of fibrils over two months with fibril length growing from 35.9  ±  3.0 nm to 51.5  ±  2.1 nm. Structurally metastable fibrils with distinct SAXS profiles have been identified. As proof of concept, we demonstrate the use of such distinct SAXS profiles to detect fibrils in the mixture solutions of two species by estimating their volume fractions. This easily detectable and well-characterized amyloid fibril model from BSA can be readily used as a control or standard reference to further investigate SAXS applications in the detection of structurally diverse amyloid fibrils associated with protein aggregation diseases.

  18. PINPIN a-Si:H based structures for X-ray image detection using the laser scanning technique

    Science.gov (United States)

    Fernandes, M.; Vygranenko, Y.; Vieira, M.

    2015-05-01

    Conventional film based X-ray imaging systems are being replaced by their digital equivalents. Different approaches are being followed by considering direct or indirect conversion, with the later technique dominating. The typical, indirect conversion, X-ray panel detector uses a phosphor for X-ray conversion coupled to a large area array of amorphous silicon based optical sensors and a couple of switching thin film transistors (TFT). The pixel information can then be readout by switching the correspondent line and column transistors, routing the signal to an external amplifier. In this work we follow an alternative approach, where the electrical switching performed by the TFT is replaced by optical scanning using a low power laser beam and a sensing/switching PINPIN structure, thus resulting in a simpler device. The optically active device is a PINPIN array, sharing both front and back electrical contacts, deposited over a glass substrate. During X-ray exposure, each sensing side photodiode collects photons generated by the scintillator screen (560 nm), charging its internal capacitance. Subsequently a laser beam (445 nm) scans the switching diodes (back side) retrieving the stored charge in a sequential way, reconstructing the image. In this paper we present recent work on the optoelectronic characterization of the PINPIN structure to be incorporated in the X-ray image sensor. The results from the optoelectronic characterization of the device and the dependence on scanning beam parameters are presented and discussed. Preliminary results of line scans are also presented.

  19. Synthesis, spectral and single crystal X-ray structural studies on bis(2,2’-bipyridinesulphidoM(II (M = Cu or Zn and diaqua 2,2’-bipyridine zinc(IIsulphate dihydrate

    Directory of Open Access Journals (Sweden)

    ARUMUGAM MANOHAR

    2010-08-01

    Full Text Available Reaction of bis(diethanoldithiocarbamatocopper(II, [Cu(deadtc2] and bis(di-n-propyldithiocarbamatozinc(II, [Zn(dnpdtc2] complexes with 2,2’-bipyridine (2,2’-bipy (1:1 ratio in ethanol was investigated. Simple mixing of the reactants in 1:1 ratio resulted in five-coordinated [Cu(2,2’--bipy2S]•CH3CH2OSO3H (1 and [Zn(2,2’-bipy2S]•CH3CH2OSO3H·2H2O (2. Refluxing the reactants and cooling the contents result in the formation of [Zn(2,2’-bipy(H2O2]SO4 (3 and [Cu(2,2’-bipy(H2O2]SO4 (4. Complexes 1 and 2 are monomeric with trigonal bipyramidal geometry. A distorted octahedral environment was observed in complexes 3 and 4. The crystal structure of 4 has already been reported in the literature. Crystal structures of 1, 2 and 3 are reported in this paper. The M–S distances in 1 and 2 are 2.318(1 Å and 2.323 Å, respectively. The N–M–S angles are larger than the N–M–N angles due to the steric requirements.

  20. X-ray structure of a soluble Rieske-type ferredoxin from Mus musculus

    International Nuclear Information System (INIS)

    Levin, Elena J.; Elsen, Nathaniel L.; Seder, Kory D.; McCoy, Jason G.; Fox, Brian G.; Phillips Jr, George N.

    2008-01-01

    The X-ray crystal structure of a soluble Rieske ferredoxin from M. musculus was solved at 2.07 Å resolution, revealing an iron–sulfur cluster-binding domain with similar architecture to the Rieske-type domains of bacterial aromatic dioxygenases. The ferredoxin was also shown to be capable of accepting electrons from both eukaryotic and prokaryotic oxidoreductases. The 2.07 Å resolution X-ray crystal structure of a soluble Rieske-type ferredoxin from Mus musculus encoded by the gene Mm.266515 is reported. Although they are present as covalent domains in eukaryotic membrane oxidase complexes, soluble Rieske-type ferredoxins have not previously been observed in eukaryotes. The overall structure of the mouse Rieske-type ferredoxin is typical of this class of iron–sulfur proteins and consists of a larger partial β-barrel domain and a smaller domain containing Cys57, His59, Cys80 and His83 that binds the [2Fe–2S] cluster. The S atoms of the cluster are hydrogen-bonded by six backbone amide N atoms in a pattern typical of membrane-bound high-potential eukaryotic respiratory Rieske ferredoxins. However, phylogenetic analysis suggested that the mouse Rieske-type ferredoxin was more closely related to bacterial Rieske-type ferredoxins. Correspondingly, the structure revealed an extended loop most similar to that seen in Rieske-type ferredoxin subunits of bacterial aromatic dioxygenases, including the positioning of an aromatic side chain (Tyr85) between this loop and the [2Fe–2S] cluster. The mouse Rieske-type ferredoxin was shown to be capable of accepting electrons from both eukaryotic and prokaryotic oxidoreductases, although it was unable to serve as an electron donor for a bacterial monooxygenase complex. The human homolog of mouse Rieske-type ferredoxin was also cloned and purified. It behaved identically to mouse Rieske-type ferredoxin in all biochemical characterizations but did not crystallize. Based on its high sequence identity, the structure of the

  1. High-resolution X-ray crystal structure of bovine H-protein using the high-pressure cryocooling method

    International Nuclear Information System (INIS)

    Higashiura, Akifumi; Ohta, Kazunori; Masaki, Mika; Sato, Masaru; Inaka, Koji; Tanaka, Hiroaki; Nakagawa, Atsushi

    2013-01-01

    Using the high-pressure cryocooling method, the high-resolution X-ray crystal structure of bovine H-protein was determined at 0.86 Å resolution. This is the first ultra-high-resolution structure obtained from a high-pressure cryocooled crystal. Recently, many technical improvements in macromolecular X-ray crystallography have increased the number of structures deposited in the Protein Data Bank and improved the resolution limit of protein structures. Almost all high-resolution structures have been determined using a synchrotron radiation source in conjunction with cryocooling techniques, which are required in order to minimize radiation damage. However, optimization of cryoprotectant conditions is a time-consuming and difficult step. To overcome this problem, the high-pressure cryocooling method was developed (Kim et al., 2005 ▶) and successfully applied to many protein-structure analyses. In this report, using the high-pressure cryocooling method, the X-ray crystal structure of bovine H-protein was determined at 0.86 Å resolution. Structural comparisons between high- and ambient-pressure cryocooled crystals at ultra-high resolution illustrate the versatility of this technique. This is the first ultra-high-resolution X-ray structure obtained using the high-pressure cryocooling method

  2. X-ray Absorption Fine Structure (XAFS) Studies of Oxide Glasses—A 45-Year Overview

    Science.gov (United States)

    Zanotto, Edgar Dutra

    2018-01-01

    X-ray Absorption Fine Structure (XAFS) spectroscopy has been widely used to characterize the short-range order of glassy materials since the theoretical basis was established 45 years ago. Soon after the technique became accessible, mainly due to the existence of Synchrotron laboratories, a wide range of glassy materials was characterized. Silicate glasses have been the most studied because they are easy to prepare, they have commercial value and are similar to natural glasses, but borate, germanate, phosphate, tellurite and other less frequent oxide glasses have also been studied. In this manuscript, we review reported advances in the structural characterization of oxide-based glasses using this technique. A focus is on structural characterization of transition metal ions, especially Ti, Fe, and Ni, and their role in different properties of synthetic oxide-based glasses, as well as their important function in the formation of natural glasses and magmas, and in nucleation and crystallization. We also give some examples of XAFS applications for structural characterization of glasses submitted to high pressure, glasses used to store radioactive waste and medieval glasses. This updated, comprehensive review will likely serve as a useful guide to clarify the details of the short-range structure of oxide glasses. PMID:29382102

  3. Electronic structure analysis of UO2 by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Ozkendir, O.M.

    2009-01-01

    Full text: Due to the essential role of Actinides in nuclear science and technology, electronic and structural investigations of actinide compounds attract major interest in science. Electronic structure of actinide compounds have important properties due to narrow 5f states which play key role in bonding with anions. The properties of Uranium has been a subject of enduring interest due to its being a major importance as a nuclear fuel and is the highest numbered element which can be found naturally on earth. UO 2 forms as a secondary uranyl group occurred during metamictization of uranium oxide compounds [1].Uranium oxide thin films have been investigated by X-ray Absorption Fine Structure spectroscopy (XAFS) [2]. The full multiple scattering approach has been applied to the calculation of U L3 edge spectra of UO 2 . The calculations are based on different choices of one electron potentials according to Uranium coordinations by using the real space multiple scattering method FEFF 8.2 code [3,4]. U L3-edge absorption spectrum in UO 2 is compared with U L3-edges in USiO 4 and UTe which are chosen due to their different electronic and chemical structures.We have found prominent changes in the XANES spectra of Uranium oxide thin films due to valency properties. Such observed changes are explained by considering the structural, electronic and spectroscopic properties. (author)

  4. Novel X-ray phase-contrast tomography method for quantitative studies of heat induced structural changes in meat

    DEFF Research Database (Denmark)

    Miklos, Rikke; Nielsen, Mikkel Schou; Einarsdottir, Hildur

    2014-01-01

    The objective of this study was to evaluate the use of X-ray phase-contrast tomography combined with 3D image segmentation to investigate the heat induced structural changes in meat. The measurements were performed at the Swiss synchrotron radiation light source using a grating interferometric...... and separated into a water phase and a gel phase formed by the sarcoplasmic proteins in the exudate. The results show that X-ray phase contrast tomography offers unique possibilities in studies both the meat structure and the different meat component such as water, fat, connective tissue and myofibrils...

  5. Fast automatic segmentation of anatomical structures in x-ray computed tomography images to improve fluorescence molecular tomography reconstruction.

    Science.gov (United States)

    Freyer, Marcus; Ale, Angelique; Schulz, Ralf B; Zientkowska, Marta; Ntziachristos, Vasilis; Englmeier, Karl-Hans

    2010-01-01

    The recent development of hybrid imaging scanners that integrate fluorescence molecular tomography (FMT) and x-ray computed tomography (XCT) allows the utilization of x-ray information as image priors for improving optical tomography reconstruction. To fully capitalize on this capacity, we consider a framework for the automatic and fast detection of different anatomic structures in murine XCT images. To accurately differentiate between different structures such as bone, lung, and heart, a combination of image processing steps including thresholding, seed growing, and signal detection are found to offer optimal segmentation performance. The algorithm and its utilization in an inverse FMT scheme that uses priors is demonstrated on mouse images.

  6. Synthesis and characterization of new N-(diphenylphosphino)-naphthylamine chalcogenides: X-ray structures of (1-NHC 10H 7)P(Se)Ph 2 and Ph 2P(S)OP(S)Ph 2

    KAUST Repository

    Tomah Al-Masri, Harbi; Emwas, Abdul-Hamid M.; Al-Talla, Zeyad; Al Kordi, Mohamed

    2012-01-01

    The reaction of 1-naphthylamine with one equivalent of chlorodiphenylphosphine in the presence of triethylamine gave the (1-NHC 10H 7)PPh 2 (1) ligand. Refluxing of 1 with elemental sulfur or grey selenium in toluene (1:1 molar ratio) afforded (1-NHC 10H 7)P(S)Ph 2 (2) and (1-NHC 10H 7)P(Se)Ph 2 (3), respectively. Moreover, the byproduct {Ph 2P(S)} 2O (4) was isolated from the reaction of 1 with elemental sulfur. Compounds 1-3 were identified and characterized by multinuclear ( 1H, 13C, 31P, 77Se) NMR spectroscopy, mass spectrometry, and elemental analysis. Crystal structure determinations of 3 and 4 were carried out. Copyright © 2012 Taylor and Francis Group, LLC.

  7. Synthesis and characterization of new N-(diphenylphosphino)-naphthylamine chalcogenides: X-ray structures of (1-NHC 10H 7)P(Se)Ph 2 and Ph 2P(S)OP(S)Ph 2

    KAUST Repository

    Tomah Al-Masri, Harbi

    2012-09-01

    The reaction of 1-naphthylamine with one equivalent of chlorodiphenylphosphine in the presence of triethylamine gave the (1-NHC 10H 7)PPh 2 (1) ligand. Refluxing of 1 with elemental sulfur or grey selenium in toluene (1:1 molar ratio) afforded (1-NHC 10H 7)P(S)Ph 2 (2) and (1-NHC 10H 7)P(Se)Ph 2 (3), respectively. Moreover, the byproduct {Ph 2P(S)} 2O (4) was isolated from the reaction of 1 with elemental sulfur. Compounds 1-3 were identified and characterized by multinuclear ( 1H, 13C, 31P, 77Se) NMR spectroscopy, mass spectrometry, and elemental analysis. Crystal structure determinations of 3 and 4 were carried out. Copyright © 2012 Taylor and Francis Group, LLC.

  8. Quantitative Analysis of Micro-Structure in Meat Emulsions from Grating-Based Multimodal X-Ray Tomography

    DEFF Research Database (Denmark)

    Einarsdottir, Hildur; Nielsen, Mikkel Schou; Miklos, Rikke

    2013-01-01

    Using novel X-ray techniques, based on grating-interferometry, new imaging modalities can be obtained simultaneously with absorption computed tomography (CT). These modalities, called phase contrast and dark field imaging, measure the electron density and the diffusion length of the sample....... Enhanced contrast capabilities of this X-ray technique makes studies on materials with similar attenuation properties possible. In this paper the focus is set on processing grating-based X-ray tomograms of meat emulsions to quantitatively measure micro-structural changes due to heat treatment. The emulsion...... samples were imaged both in a raw and cooked state. Additionally, different fat types were used in the emulsions in order to compare micro-structural differences when either pork fat or sunflower oil was used. From the reconstructed tomograms the different ingredients in the emulsions were segmented using...

  9. X-ray television area detectors for macromolecular structural studies with synchrotron radiation sources

    International Nuclear Information System (INIS)

    Arndt, U.W.; Gilmore, D.J.

    1978-01-01

    Two-dimensional X-ray diffraction patterns may be recorded quantitatively by means of X-ray-to-electron converters which are scanned in a television-type raster scan. Detectors of this type are capable of operating over the whole range of counting rates from very low to higher than those with which other types of converters can deal. The component parts of an X-ray television detector are examined and the limits to the precision of the measurements are analysed. (Auth.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-04-01

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

  11. PINPIN a-Si:H based structures for X-ray image detection using the laser scanning technique

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, M., E-mail: mfernandes@isel.pt [Electronics Telecommunication and Computer Dept., ISEL, R.Conselheiro Emídio Navarro, 1959-007 Lisboa (Portugal); CTS-UNINOVA Quinta da Torre, Monte da Caparica, 2829-516 Caparica (Portugal); Vygranenko, Y.; Vieira, M. [Electronics Telecommunication and Computer Dept., ISEL, R.Conselheiro Emídio Navarro, 1959-007 Lisboa (Portugal); CTS-UNINOVA Quinta da Torre, Monte da Caparica, 2829-516 Caparica (Portugal)

    2015-05-01

    Highlights: • We present novel structure for X-ray image sensor based on the laser scanned technique. • Amorphous silicon based tandem structure characterization results are presented and discussed. • Results from preliminary tests of the imaging application are promising for very large area image sensing. - Abstract: Conventional film based X-ray imaging systems are being replaced by their digital equivalents. Different approaches are being followed by considering direct or indirect conversion, with the later technique dominating. The typical, indirect conversion, X-ray panel detector uses a phosphor for X-ray conversion coupled to a large area array of amorphous silicon based optical sensors and a couple of switching thin film transistors (TFT). The pixel information can then be readout by switching the correspondent line and column transistors, routing the signal to an external amplifier. In this work we follow an alternative approach, where the electrical switching performed by the TFT is replaced by optical scanning using a low power laser beam and a sensing/switching PINPIN structure, thus resulting in a simpler device. The optically active device is a PINPIN array, sharing both front and back electrical contacts, deposited over a glass substrate. During X-ray exposure, each sensing side photodiode collects photons generated by the scintillator screen (560 nm), charging its internal capacitance. Subsequently a laser beam (445 nm) scans the switching diodes (back side) retrieving the stored charge in a sequential way, reconstructing the image. In this paper we present recent work on the optoelectronic characterization of the PINPIN structure to be incorporated in the X-ray image sensor. The results from the optoelectronic characterization of the device and the dependence on scanning beam parameters are presented and discussed. Preliminary results of line scans are also presented.

  12. Down-regulation of SMT3A gene expression in association with DNA synthesis induction after X-ray irradiation in nevoid basal cell carcinoma syndrome (NBCCS) cells

    International Nuclear Information System (INIS)

    Sugaya, Shigeru; Nakanishi, Hiroshi; Tanzawa, Hideki; Sugita, Katsuo; Kita, Kazuko; Suzuki, Nobuo

    2005-01-01

    Fibroblast cells derived from nevoid basal carcinoma syndrome (NBCCS) patients show increased levels of DNA synthesis after X-ray irradiation. Genes, whose expression is modulated in association with the DNA synthesis induction, were searched by using PCR-based mRNA differential display analysis in one of the NBCCS cell lines, NBCCS1 cells. Decreased levels of SMT3A gene expression were found in X-ray-irradiated NBCCS1 cells. This decrease was also shown by RT-PCR analysis in another cell line, NBCCS3 cells. In addition to NBCCS cells, normal fibroblast cells showed the DNA synthesis induction after X-ray irradiation when they were treated with antisense oligonucleotides (AO) for SMT3A. However, treatment of normal fibroblasts with the random oligonucleotides (RO) resulted in decreased levels of DNA synthesis after X-ray irradiation. Thus, down-regulation of SMT3A gene expression may be involved in the DNA synthesis induction after X-ray irradiation in the NBCCS cells at least tested

  13. Down-regulation of SMT3A gene expression in association with DNA synthesis induction after X-ray irradiation in nevoid basal cell carcinoma syndrome (NBCCS) cells

    Energy Technology Data Exchange (ETDEWEB)

    Sugaya, Shigeru [Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670 (Japan); Nakanishi, Hiroshi [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670 (Japan); Tanzawa, Hideki [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670 (Japan); Sugita, Katsuo [Department of Clinical Medicine, Faculty of Education, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522 (Japan); Kita, Kazuko [Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670 (Japan); Suzuki, Nobuo [Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670 (Japan)]. E-mail: nobuo@faculty.chiba-u.jp

    2005-10-15

    Fibroblast cells derived from nevoid basal carcinoma syndrome (NBCCS) patients show increased levels of DNA synthesis after X-ray irradiation. Genes, whose expression is modulated in association with the DNA synthesis induction, were searched by using PCR-based mRNA differential display analysis in one of the NBCCS cell lines, NBCCS1 cells. Decreased levels of SMT3A gene expression were found in X-ray-irradiated NBCCS1 cells. This decrease was also shown by RT-PCR analysis in another cell line, NBCCS3 cells. In addition to NBCCS cells, normal fibroblast cells showed the DNA synthesis induction after X-ray irradiation when they were treated with antisense oligonucleotides (AO) for SMT3A. However, treatment of normal fibroblasts with the random oligonucleotides (RO) resulted in decreased levels of DNA synthesis after X-ray irradiation. Thus, down-regulation of SMT3A gene expression may be involved in the DNA synthesis induction after X-ray irradiation in the NBCCS cells at least tested.

  14. xMDFF: molecular dynamics flexible fitting of low-resolution X-ray structures.

    Science.gov (United States)

    McGreevy, Ryan; Singharoy, Abhishek; Li, Qufei; Zhang, Jingfen; Xu, Dong; Perozo, Eduardo; Schulten, Klaus

    2014-09-01

    X-ray crystallography remains the most dominant method for solving atomic structures. However, for relatively large systems, the availability of only medium-to-low-resolution diffraction data often limits the determination of all-atom details. A new molecular dynamics flexible fitting (MDFF)-based approach, xMDFF, for determining structures from such low-resolution crystallographic data is reported. xMDFF employs a real-space refinement scheme that flexibly fits atomic models into an iteratively updating electron-density map. It addresses significant large-scale deformations of the initial model to fit the low-resolution density, as tested with synthetic low-resolution maps of D-ribose-binding protein. xMDFF has been successfully applied to re-refine six low-resolution protein structures of varying sizes that had already been submitted to the Protein Data Bank. Finally, via systematic refinement of a series of data from 3.6 to 7 Å resolution, xMDFF refinements together with electrophysiology experiments were used to validate the first all-atom structure of the voltage-sensing protein Ci-VSP.

  15. Study of the structural modifications in activated clays by Moessbauer spectroscopy and X-ray diffractometry

    Energy Technology Data Exchange (ETDEWEB)

    Huaypar, Yezena, E-mail: yhuaypar@yahoo.es; Bravo, Jorge, E-mail: jbravoc@unmsm.edu.pe [Universidad Nacional Mayor de San Marcos, Facultad de Ciencias Fisicas (Peru); Gutarra, Abel; Gabriel, Erika [Universidad Nacional de Ingenieria, Facultad de Ciencias (Peru)

    2007-02-15

    In this work we study the changes induced on the structure of a smectite clay by chemical acid activation with HCl using X-ray diffractometry (XRD) and transmission Moessbauer spectroscopy (TMS) techniques. By XRD we were able to determine the mineralogical composition of the clay samples and measure the changes in the interplanar distance associated to the structural modifications in the clays. We measured a reduction in the interplanar distance and reflection intensity as the acid concentration in the activation process increased. TMS allowed us identify and characterize the structural sites occupied by ferric and ferrous iron cations. In addition, we were able to monitor the effects caused by the chemical acid activation on the valence state of the iron cations that occupy these structural sites in the clay. For the treatment at low acid concentration, keeping time and temperature of activation constant, our results showed a strong effect on the ferrous and ferric iron sites, reducing and increasing their adsorption relative areas respectively.

  16. Study of the structural modifications in activated clays by Moessbauer spectroscopy and X-ray diffractometry

    International Nuclear Information System (INIS)

    Huaypar, Yezena; Bravo, Jorge; Gutarra, Abel; Gabriel, Erika

    2007-01-01

    In this work we study the changes induced on the structure of a smectite clay by chemical acid activation with HCl using X-ray diffractometry (XRD) and transmission Moessbauer spectroscopy (TMS) techniques. By XRD we were able to determine the mineralogical composition of the clay samples and measure the changes in the interplanar distance associated to the structural modifications in the clays. We measured a reduction in the interplanar distance and reflection intensity as the acid concentration in the activation process increased. TMS allowed us identify and characterize the structural sites occupied by ferric and ferrous iron cations. In addition, we were able to monitor the effects caused by the chemical acid activation on the valence state of the iron cations that occupy these structural sites in the clay. For the treatment at low acid concentration, keeping time and temperature of activation constant, our results showed a strong effect on the ferrous and ferric iron sites, reducing and increasing their adsorption relative areas respectively.

  17. Crystal structure investigations on cation-substituted alums by X-ray and neutron diffraction

    International Nuclear Information System (INIS)

    Abdeen, A.M.

    1980-04-01

    The crystal structures of the three alums: NH 4 Al(SO 4 ) 2 .12H 2 O, (NH 3 CH 3 )Al(SO 4 ) 2 .12H 2 O and (NH 3 OH)Al(SO 4 ) 2 .12H 2 O have been determined from three-dimensional neutron diffraction data enhanced by X-ray diffraction when necessary. These compounds crystallize cubic in space group Pa3. The structures of the three alums exhibit partial occupancies of crystallographic sites for the NH 4 , (NH 3 CH 3 ) and (NH 3 OH) group atoms. This can be explained by a quantized rotation of the three groups around an axis perpendicular to the [111] direction. Some of the (SO 4 ) 2- groups in the NH 4 -alum are disordered with about 17% of the sulfate tetrahedra being in a reversed orientation around the sulfur atom. The disorder in (NH 3 CH 3 ) and (NH 3 OH)-alums is only 4,3% and 3.0% respectively. The atoms in the alum structures are held together by a system of hydrogen bonds between the water molecules and between the water molecules and the sulfate oxygen atoms. In these three structures there is a strong indication that shorter hydrogen bonds tend to be nearly linear. (orig.)

  18. M31 GLOBULAR CLUSTER STRUCTURES AND THE PRESENCE OF X-RAY BINARIES

    International Nuclear Information System (INIS)

    Agar, J. R. R.; Barmby, P.

    2013-01-01

    The Andromeda galaxy, M31, has several times the number of globular clusters found in the Milky Way. It contains a correspondingly larger number of low-mass X-ray binaries (LMXBs) associated with globular clusters, and as such can be used to investigate the cluster properties that lead to X-ray binary formation. The best tracer of the spatial structure of M31 globulars is the high-resolution imaging available from the Hubble Space Telescope (HST), and we have used HST data to derive structural parameters for 29 LMXB-hosting M31 globular clusters. These measurements are combined with structural parameters from the literature for a total of 41 (of 50 known) LMXB clusters and a comparison sample of 65 non-LMXB clusters. Structural parameters measured in blue bandpasses are found to be slightly different (smaller core radii and higher concentrations) than those measured in red bandpasses; this difference is enhanced in LMXB clusters and could be related to stellar population differences. Clusters with LMXBs show higher collision rates for their mass compared to clusters without LMXBs, and collision rates estimated at the core radius show larger offsets than rates estimated at the half-light radius. These results are consistent with the dynamical formation scenario for LMXBs. A logistic regression analysis finds that, as expected, the probability of a cluster hosting an LMXB increases with increasing collision rate and proximity to the galaxy center. The same analysis finds that probability of a cluster hosting an LMXB decreases with increasing cluster mass at a fixed collision rate, although we caution that this could be due to sample selection effects. Metallicity is found to be a less important predictor of LMXB probability than collision rate, mass, or distance, even though LMXB clusters have a higher metallicity on average. This may be due to the interaction of location and metallicity: a sample of M31 LMXBs with a greater range in galactocentric distance would

  19. X-ray structure of the pestivirus NS3 helicase and its conformation in solution.

    Science.gov (United States)

    Tortorici, M Alejandra; Duquerroy, Stéphane; Kwok, Jane; Vonrhein, Clemens; Perez, Javier; Lamp, Benjamin; Bricogne, Gerard; Rümenapf, Till; Vachette, Patrice; Rey, Félix A

    2015-04-01

    Pestiviruses form a genus in the Flaviviridae family of small enveloped viruses with a positive-sense single-stranded RNA genome. Viral replication in this family requires the activity of a superfamily 2 RNA helicase contained in the C-terminal domain of nonstructural protein 3 (NS3). NS3 features two conserved RecA-like domains (D1 and D2) with ATPase activity, plus a third domain (D3) that is important for unwinding nucleic acid duplexes. We report here the X-ray structure of the pestivirus NS3 helicase domain (pNS3h) at a 2.5-Å resolution. The structure deviates significantly from that of NS3 of other genera in the Flaviviridae family in D3, as it contains two important insertions that result in a narrower nucleic acid binding groove. We also show that mutations in pNS3h that rescue viruses from which the core protein is deleted map to D3, suggesting that this domain may be involved in interactions that facilitate particle assembly. Finally, structural comparisons of the enzyme in different crystalline environments, together with the findings of small-angle X-ray-scattering studies in solution, show that D2 is mobile with respect to the rest of the enzyme, oscillating between closed and open conformations. Binding of a nonhydrolyzable ATP analog locks pNS3h in a conformation that is more compact than the closest apo-form in our crystals. Together, our results provide new insight and bring up new questions about pNS3h function during pestivirus replication. Although pestivirus infections impose an important toll on the livestock industry worldwide, little information is available about the nonstructural proteins essential for viral replication, such as the NS3 helicase. We provide here a comparative structural and functional analysis of pNS3h with respect to its orthologs in other viruses of the same family, the flaviviruses and hepatitis C virus. Our studies reveal differences in the nucleic acid binding groove that could have implications for understanding the

  20. High-energy X-ray diffraction studies of short- and intermediate-range structure in oxide glasses

    International Nuclear Information System (INIS)

    Suzuya, Kentaro

    2002-01-01

    The feature of high-energy X-ray diffraction method is explained. The oxide glasses studies by using BL04B2, high-energy X-ray diffraction beam line of SPring-8, and the random system materials by high-energy monochromatic X-ray diffraction are introduced. An advantage of third generation synchrotron radiation is summarized. On SPring-8, the high-energy X-ray diffraction experiments of random system are carried out by BL04B2 and BL14B1 beam line. BL04B2 can select Si (111)(E=37.8 keV, λ=0.033 nm) and Si(220)(E=61.7 keV, λ=0.020 nm) as Si monochromator. The intermediate-range structure of (MgO) x (P 2 O 5 ) 1-x glass ,MgP 2 O 6 glass, B 2 O 3 glass, SiO 2 and GeO 2 are explained in detail. The future and application of high-energy X-ray diffraction are stated. (S.Y.)

  1. Three-dimensional structure determination protocol for noncrystalline biomolecules using x-ray free-electron laser diffraction imaging.

    Science.gov (United States)

    Oroguchi, Tomotaka; Nakasako, Masayoshi

    2013-02-01

    Coherent and intense x-ray pulses generated by x-ray free-electron laser (XFEL) sources are paving the way for structural determination of noncrystalline biomolecules. However, due to the small scattering cross section of electrons for x rays, the available incident x-ray intensity of XFEL sources, which is currently in the range of 10(12)-10(13) photons/μm(2)/pulse, is lower than that necessary to perform single-molecule diffraction experiments for noncrystalline biomolecules even with the molecular masses of megadalton and submicrometer dimensions. Here, we propose an experimental protocol and analysis method for visualizing the structure of those biomolecules by the combined application of coherent x-ray diffraction imaging and three-dimensional reconstruction methods. To compensate the small scattering cross section of biomolecules, in our protocol, a thin vitreous ice plate containing several hundred biomolecules/μm(2) is used as sample, a setup similar to that utilized by single-molecule cryoelectron microscopy. The scattering cross section of such an ice plate is far larger than that of a single particle. The images of biomolecules contained within irradiated areas are then retrieved from each diffraction pattern, and finally provide the three-dimensional electron density model. A realistic atomic simulation using large-scale computations proposed that the three-dimensional structure determination of the 50S ribosomal subunit embedded in a vitreous ice plate is possible at a resolution of 0.8 nm when an x-ray beam of 10(16) photons/500×500 nm(2)/pulse is available.

  2. X-ray crystallographic structure determination of the smoke-derived karrikin KAR3

    Czech Academy of Sciences Publication Activity Database

    Nair, J. J.; Munro, O. Q.; Pošta, Martin; Papenfus, H. B.; Beier, Petr; van Staden, J.

    2013-01-01

    Roč. 88, September (2013), s. 107-109 ISSN 0254-6299 Institutional support: RVO:61388963 Keywords : germination * karrikin * plant growth regulator * smoke * X-ray Subject RIV: CC - Organic Chemistry Impact factor: 1.340, year: 2013

  3. Analysis of Soil Structure Turnover with Garnet Particles and X-Ray Microtomography.

    Directory of Open Access Journals (Sweden)

    Steffen Schlüter

    Full Text Available Matter turnover in soil is tightly linked to soil structure which governs the heterogeneous distribution of habitats, reaction sites and pathways in soil. Thereby, the temporal dynamics of soil structure alteration is deemed to be important for essential ecosystem functions of soil but very little is known about it. A major reason for this knowledge gap is the lack of methods to study soil structure turnover directly at microscopic scales. Here we devise a conceptual approach and an image processing workflow to study soil structure turnover by labeling some initial state of soil structure with small garnet particles and tracking their fate with X-ray microtomography. The particles adhere to aggregate boundaries at the beginning of the experiment but gradually change their position relative to the nearest pore as structure formation progresses and pores are destructed or newly formed. A new metric based on the contact distances between particles and pores is proposed that allows for a direct quantification of soil structure turnover rates. The methodology is tested for a case study about soil compaction of a silty loam soil during stepwise increase of bulk density (ρ = {1.1, 1.3, 1.5} g/cm3. We demonstrate that the analysis of mean contact distances provides genuinely new insights about changing diffusion pathways that cannot be inferred neither from conventional pore space attributes (porosity, mean pore size, pore connectivity nor from deformation analysis with digital image correlation. This structure labeling approach to quantify soil structure turnover provides a direct analogy to stable isotope labeling for the analysis of matter turnover and can be readily combined with each other.

  4. Analysis of Soil Structure Turnover with Garnet Particles and X-Ray Microtomography.

    Science.gov (United States)

    Schlüter, Steffen; Vogel, Hans-Jörg

    2016-01-01

    Matter turnover in soil is tightly linked to soil structure which governs the heterogeneous distribution of habitats, reaction sites and pathways in soil. Thereby, the temporal dynamics of soil structure alteration is deemed to be important for essential ecosystem functions of soil but very little is known about it. A major reason for this knowledge gap is the lack of methods to study soil structure turnover directly at microscopic scales. Here we devise a conceptual approach and an image processing workflow to study soil structure turnover by labeling some initial state of soil structure with small garnet particles and tracking their fate with X-ray microtomography. The particles adhere to aggregate boundaries at the beginning of the experiment but gradually change their position relative to the nearest pore as structure formation progresses and pores are destructed or newly formed. A new metric based on the contact distances between particles and pores is proposed that allows for a direct quantification of soil structure turnover rates. The methodology is tested for a case study about soil compaction of a silty loam soil during stepwise increase of bulk density (ρ = {1.1, 1.3, 1.5} g/cm3). We demonstrate that the analysis of mean contact distances provides genuinely new insights about changing diffusion pathways that cannot be inferred neither from conventional pore space attributes (porosity, mean pore size, pore connectivity) nor from deformation analysis with digital image correlation. This structure labeling approach to quantify soil structure turnover provides a direct analogy to stable isotope labeling for the analysis of matter turnover and can be readily combined with each other.

  5. X-ray CT Scanning Reveals Long-Term Copper Pollution Effects on Functional Soil Structure

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Møldrup, Per; Homstrup, Martin

    Soil structure plays the main role in the ability of the soil to fulfill essential soil functions such as the root growth, rate of water infiltration and retention, transport of gaseous and chemicals/pollutants through the soil. Soil structure is a dynamic soil property and affected by various...... factors such as soil type, land use, and soil contamination. In this study, we quantified the soil structure using X-ray CT scanning and revealed the effect of a long history of Copper (Cu) pollution on it. A fallow field at Hygum Denmark provides this opportunity as it had a long history of Copper...... sulphate contamination in a gradient with Cu content varies from 21 mg kg-1 to 3837 mg kg-1. Total 20 intact soil columns (diameter of 10 cm and height of 8 cm) were sampled at five locations along the Cu-gradient from a depth of 5 to 15 cm below surface level. The soil columns were scanned at a voxel...

  6. Monoalkylated barbiturate derivatives: X-ray crystal structure, theoretical studies, and biological activities

    Science.gov (United States)

    Barakat, Assem; Al-Majid, Abdullah Mohammed; Soliman, Saied M.; Islam, Mohammad Shahidul; Ghawas, Hussain Mansur; Yousuf, Sammer; Choudhary, M. Iqbal; Wadood, Abdul

    2017-08-01

    Barbiturate derivatives are privileged structures with a broad range of pharmaceutical applications. We prepared a series of 5-monoalkylated barbiturate derivatives (3a-l) and evaluated, in vitro, their antioxidant (DPPH assay), and α-glucosidase inhibitory activities. Compounds 3a-l were synthesized via Michael addition. The structure of compound 3k was determined using X-ray single-crystal diffraction, and geometric parameters were calculated using density functional theory at the B3LYP/6-311G(d,p) level of theory. Further, the structural analysis of 3k were also investigated. Biological studies revealed that compounds 3b (IC50 = 133.1 ± 3.2 μM), 3d (IC50 = 305 ± 7.7 μM), and 3e (IC50 = 184 ± 2.3 μM) have potent α-glucosidase enzyme inhibitors and showed greater activity than the standard drug acarbose (IC50 = 841 ± 1.73 μM). Compounds 3a-3i were found to show weak antioxidant activity against 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radicals (IC50 = 91 ± 0.75 to 122 ± 1.0 μM) when tested against a standard antioxidant, gallic acid (IC50 = 23 ± 0.43 μM).

  7. Structural investigation of spherical hollow excipient Mannit Q by X-ray microtomography.

    Science.gov (United States)

    Kajihara, Ryusuke; Noguchi, Shuji; Iwao, Yasunori; Yasuda, Yuki; Segawa, Megumi; Itai, Shigeru

    2015-11-10

    The structure of Mannit Q particles, an excipient made by spray-drying a d-mannitol solution, and Mannit Q tablets were investigated by synchrotron X-ray microtomography. The Mannit Q particles had a spherical shape with a hollow core. The shells of the particles consisted of fine needle-shaped crystals, and columnar crystals were present in the hollows. These structural features suggested the following formation mechanism for the hollow particles:during the spray-drying process, the solvent rapidly evaporated from the droplet surface, resulting in the formation of shells made of fine needle-shaped crystals.Solvent remaining inside the shells then evaporated slowly and larger columnar crystals grew as the hollows formed. Although most of the Mannit Q particles were crushed on tableting, some of the particles retained their hollow structures, probably because the columnar crystals inside the hollows functioned as props. This demonstrated that the tablets with porous void spaces may be readily manufactured using Mannit Q. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Crystallization and X-ray structure analysis of a thermostable penicillin G acylase from Alcaligenes faecalis

    International Nuclear Information System (INIS)

    Varshney, Nishant Kumar; Suresh Kumar, R.; Ignatova, Zoya; Prabhune, Asmita; Pundle, Archana; Dodson, Eleanor; Suresh, C. G.

    2012-01-01

    A thermostable penicillin G acylase from A. faecalis has been crystallized in two space groups: C222 1 and P4 1 2 1 2. X-ray diffraction data were collected to 3.3 and 3.5 Å resolution, respectively. The enzyme penicillin G acylase (EC 3.5.1.11) catalyzes amide-bond cleavage in benzylpenicillin (penicillin G) to yield 6-aminopenicillanic acid, an intermediate chemical used in the production of semisynthetic penicillins. A thermostable penicillin G acylase from Alcaligenes faecalis (AfPGA) has been crystallized using the hanging-drop vapour-diffusion method in two different space groups: C222 1 , with unit-cell parameters a = 72.9, b = 86.0, c = 260.2 Å, and P4 1 2 1 2, with unit-cell parameters a = b = 85.6, c = 298.8 Å. Data were collected at 293 K and the structure was determined using the molecular-replacement method. Like other penicillin acylases, AfPGA belongs to the N-terminal nucleophilic hydrolase superfamily, has undergone post-translational processing and has a serine as the N-terminal residue of the β-chain. A disulfide bridge has been identified in the structure that was not found in the other two known penicillin G acylase structures. The presence of the disulfide bridge is perceived to be one factor that confers higher stability to this enzyme

  9. X-ray structure of a blue complex pigment from the blue flowers of Centaurea cyanus

    International Nuclear Information System (INIS)

    Shiono, M.; Matsugaki, N.; Takeda, K.

    2005-01-01

    Full text: The blue pigment of the cornflower, named protocyanin, has long been investigated, but its precise structure has remained unclear. Our recent research demonstrated the components of protocyanin to be anthocyanin (AN), flavone glycoside (FL), Fe 3+ , Mg 2+ and Ca 2+ ions and we succeeded in the reconstruction of protocyanin. In this study, we revealed the X-ray structure of protocyanin. The crystal structure of the reconstructed protocyanin was determined at a resolution of 1.05 A. The refined molecule has pseudo threefold symmetry and four metal ions, Fe 3+ , Mg 2+ and two Ca 2+ , align along the pseudo three-fold axis. The four metals are coordinated to six AN molecules and six FL molecules. The inner Fe 3+ and Mg 2+ ions are each coordinated to three AN molecules respectively, while the outer two Ca 2+ ions are each coordinated to three FL molecules . Both AN and FL molecules are self-associated with each other as AN-AN and FL-FL in pair and this hydrophobic association also exists between AN and FL molecules. Protocyanin is a tetra-metal (Fe 3+ , Mg 2+ , 2Ca 2+ ) nuclear complex of twelve molecules of anthocyanin and flavone glycoside, a new type of supramolecular pigment. (author)

  10. High-resolution x-ray imaging using a structured scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Hormozan, Yashar, E-mail: hormozan@kth.se; Sychugov, Ilya; Linnros, Jan [Materials and Nano Physics, School of Information and Communication Technology, KTH Royal Institute of Technology, Electrum 229, Kista, Stockholm SE-16440 (Sweden)

    2016-02-15

    Purpose: In this study, the authors introduce a new generation of finely structured scintillators with a very high spatial resolution (a few micrometers) compared to conventional scintillators, yet maintaining a thick absorbing layer for improved detectivity. Methods: Their concept is based on a 2D array of high aspect ratio pores which are fabricated by ICP etching, with spacings (pitches) of a few micrometers, on silicon and oxidation of the pore walls. The pores were subsequently filled by melting of powdered CsI(Tl), as the scintillating agent. In order to couple the secondary emitted photons of the back of the scintillator array to a CCD device, having a larger pixel size than the pore pitch, an open optical microscope with adjustable magnification was designed and implemented. By imaging a sharp edge, the authors were able to calculate the modulation transfer function (MTF) of this finely structured scintillator. Results: The x-ray images of individually resolved pores suggest that they have been almost uniformly filled, and the MTF measurements show the feasibility of a few microns spatial resolution imaging, as set by the scintillator pore size. Compared to existing techniques utilizing CsI needles as a structured scintillator, their results imply an almost sevenfold improvement in resolution. Finally, high resolution images, taken by their detector, are presented. Conclusions: The presented work successfully shows the functionality of their detector concept for high resolution imaging and further fabrication developments are most likely to result in higher quantum efficiencies.

  11. Structural analysis of polymer thin films using GISAXS in the tender X-ray region: Concept and design of GISAXS experiments using the tender X-ray energy at BL-15A2 at the Photon Factory

    Energy Technology Data Exchange (ETDEWEB)

    Takagi, H., E-mail: takagih@post.kek.jp; Igarashi, N.; Mori, T.; Saijo, S.; Nagatani, Y.; Shimizu, N. [Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Ohta, H. [Mitsubishi Electric System & Service Co., Ltd, Accelerator Engineering Center, 2-8- 8 Umezono, Tsukuba, Ibaraki 305-0045 (Japan); Yamamoto, K. [Graduate School of Engineering, Department of Materials Science & Technology, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2016-10-14

    If small angle X-ray scattering (SAXS) utilizing the soft X-ray region is available, advanced and unique experiments, which differ from traditional SAXS methods, can be realized. For example, grazing-incidence small angle X-ray scattering (GISAXS) using hard X-ray is a powerful tool for understanding the nanostructure in both vertical and lateral directions of thin films, while GISAXS utilizing the tender X-ray region (SX-GISAXS) enables depth-resolved analysis as well as a standard GISAXS analysis in thin films. Thus, at BL-15A2 at the Photon Factory, a dedicated diffractometer for SX-GISAXS (above 2.1 keV) was constructed. This diffractometer is composed of four vacuum chambers and can be converted into the vacuum state from the sample chamber in front of the detector surface. Diffractions are clearly observed until 12th peak when measuring collagen by SAXS with an X-ray energy of 2.40 keV and a camera length of 825 mm. Additionally, we conducted the model experiment using SX-GISAXS with an X-ray energy of 2.40 keV to confirm that a poly(methyl methacrylate)-poly(n-butyl acrylate) block copolymer thin film has a microphase-separated structure in the thin film, which is composed of lamellae aligned both parallel and perpendicular to the substrate surface. Similarly, in a polystyrene-poly(methyl methacrylate) block copolymer thin film, SX-GISAXS with 3.60 keV and 5.73 keV revealed that hexagonally packed cylinders are aligned parallel to the substrate surface. The incident angle dependence of the first order peak position of the q{sub z} direction obtained from experiments at various incident X-ray energies agrees very well with the theoretical one calculated from the distorted wave Born approximation.

  12. Structural analysis of polymer thin films using GISAXS in the tender X-ray region: Concept and design of GISAXS experiments using the tender X-ray energy at BL-15A2 at the Photon Factory

    International Nuclear Information System (INIS)

    Takagi, H.; Igarashi, N.; Mori, T.; Saijo, S.; Nagatani, Y.; Shimizu, N.; Ohta, H.; Yamamoto, K.

    2016-01-01

    If small angle X-ray scattering (SAXS) utilizing the soft X-ray region is available, advanced and unique experiments, which differ from traditional SAXS methods, can be realized. For example, grazing-incidence small angle X-ray scattering (GISAXS) using hard X-ray is a powerful tool for understanding the nanostructure in both vertical and lateral directions of thin films, while GISAXS utilizing the tender X-ray region (SX-GISAXS) enables depth-resolved analysis as well as a standard GISAXS analysis in thin films. Thus, at BL-15A2 at the Photon Factory, a dedicated diffractometer for SX-GISAXS (above 2.1 keV) was constructed. This diffractometer is composed of four vacuum chambers and can be converted into the vacuum state from the sample chamber in front of the detector surface. Diffractions are clearly observed until 12th peak when measuring collagen by SAXS with an X-ray energy of 2.40 keV and a camera length of 825 mm. Additionally, we conducted the model experiment using SX-GISAXS with an X-ray energy of 2.40 keV to confirm that a poly(methyl methacrylate)-poly(n-butyl acrylate) block copolymer thin film has a microphase-separated structure in the thin film, which is composed of lamellae aligned both parallel and perpendicular to the substrate surface. Similarly, in a polystyrene-poly(methyl methacrylate) block copolymer thin film, SX-GISAXS with 3.60 keV and 5.73 keV revealed that hexagonally packed cylinders are aligned parallel to the substrate surface. The incident angle dependence of the first order peak position of the q_z direction obtained from experiments at various incident X-ray energies agrees very well with the theoretical one calculated from the distorted wave Born approximation.

  13. Time-resolved pump and probe x-ray absorption fine structure spectroscopy at beamline P11 at PETRA III

    Energy Technology Data Exchange (ETDEWEB)

    Göries, D., E-mail: dennis.goeries@desy.de; Roedig, P.; Stübe, N.; Meyer, J.; Warmer, M.; Weckert, E.; Meents, A., E-mail: alke.meents@desy.de [DESY Photon Science, Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg (Germany); Dicke, B.; Naumova, M.; Rübhausen, M. [Center for Free-Electron Laser Science (CFEL), Luruper Chaussee 149, 22761 Hamburg (Germany); Galler, A.; Gawelda, W.; Geßler, P.; Sotoudi Namin, H.; Beckmann, A. [European XFEL, Albert-Einstein Ring 19, 22761 Hamburg (Germany); Britz, A.; Bressler, C. [European XFEL, Albert-Einstein Ring 19, 22761 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany); Schlie, M. [Institut für Experimentalphysik, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2016-05-15

    We report about the development and implementation of a new setup for time-resolved X-ray absorption fine structure spectroscopy at beamline P11 utilizing the outstanding source properties of the low-emittance PETRA III synchrotron storage ring in Hamburg. Using a high intensity micrometer-sized X-ray beam in combination with two positional feedback systems, measurements were performed on the transition metal complex fac-Tris[2-phenylpyridinato-C2,N]iridium(III) also referred to as fac-Ir(ppy){sub 3}. This compound is a representative of the phosphorescent iridium(III) complexes, which play an important role in organic light emitting diode (OLED) technology. The experiment could directly prove the anticipated photoinduced charge transfer reaction. Our results further reveal that the temporal resolution of the experiment is limited by the PETRA III X-ray bunch length of ∼103 ps full width at half maximum (FWHM).

  14. Lattice distortions in TlInSe{sub 2} thermoelectric material studied by X-ray absorption fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Hosokawa, Shinya; Stellhorn, Jens Ruediger [Department of Physics, Kumamoto University, Kumamoto (Japan); Ikemoto, Hiroyuki [Department of Physics, University of Toyama, Toyama (Japan); Mimura, Kojiro [Department of Mathematical Sciences, Graduate School of Engineering, Osaka Prefecture University, Sakai (Japan); Wakita, Kazuki [Faculty of Engineering, Chiba Institute of Technology, Narashino (Japan); Mamedov, Nazim [Institute of Physics, Azerbaijan National Academy of Sciences, Baku (Azerbaijan)

    2018-01-15

    Tl L{sub II} and In K X-ray absorption fine structure (XAFS) measurements were performed on a TlInSe{sub 2} thermoelectric material in the temperature range of 25-300 K including the incommensurate-commensurate phase transition temperature of about 135 K. Most of the bond lengths obtained from the present XAFS measurements are in good agreement with existing X-ray diffraction data at room temperature, while only the Tl-Tl correlation shows inconsistent values indicating the commensurate properties of the Tl chains expected from the thermodynamic properties. The present XAFS data clearly support positional fluctuations of the Tl atoms found in three-dimensional atomic images reconstructed from X-ray fluorescence holography. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Synthesis, x-ray crystallography and leishmanicidal activity of benzimidazolinyl piperidine derivative

    International Nuclear Information System (INIS)

    Saify, Z.S.; Begum, N.; Yousuf, S.; Ashraf, S.

    2014-01-01

    Protozoan parasites of the Leishmania genus are the main cause of vector-borne disease leishmaniasis throughout the world. It is caused by at least 17 different species of protozoan Leishmania and transmitted by the bite of infected sand flies. Leishmaniasis could be fatal. Present drugs have limitations to cure it due to the development of drug resistance. Hence, to design an effective leishmanicidal agent would be of great interest. Benzimidazolinyl piperidine has served as potential target due to a vast range of biological activities. In the present study a new 4-(2-keto-1-benzimidazolinyl)piperidine derivative, 1-(2-(4-fluorophenyl)-2-oxoethyl)-4-(2-oxo-2,3-dihydro-1H-benzo(d)imidazol) piperidinium bromide has been synthesized and characterized by X-ray crystallography, 1D and 2D NMR spectroscopy. Evaluation by in vitro leishmanicidal assay showed good activity. (author)

  16. Facile Low Temperature Hydrothermal Synthesis of BaTiO3 Nanoparticles Studied by In Situ X-ray Diffraction

    Directory of Open Access Journals (Sweden)

    Ola G. Grendal

    2018-06-01

    Full Text Available Ferroelectric materials are crucial for today’s technological society and nanostructured ferroelectric materials are important for the downscaling of devices. Controlled and reproducible synthesis of these materials are, therefore, of immense importance. Hydrothermal synthesis is a well-established synthesis route, with a large parameter space for optimization, but a better understanding of nucleation and growth mechanisms is needed for full utilization and control. Here we use in situ X-ray diffraction to follow the nucleation and growth of BaTiO3 formed by hydrothermal synthesis using two different titanium precursors, an amorphous titania precipitate slurry and a Ti-citric acid complex solution. Sequential Rietveld refinement was used to extract the time dependency of lattice parameters, crystallite size, strain, and atomic displacement parameters. Phase pure BaTiO3 nanoparticles, 10–15 nm in size, were successfully synthesized at different temperatures (100, 125, and 150 °C from both precursors after reaction times, ranging from a few seconds to several hours. The two precursors resulted in phase pure BaTiO3 with similar final crystallite size. Finally, two different growth mechanisms were revealed, where the effect of surfactants present during hydrothermal synthesis is discussed as one of the key parameters.

  17. A cell for extended x-ray absorption fine structure studies of oxygen sensitive products of redox reactions

    International Nuclear Information System (INIS)

    Furenlid, L.R.; Renner, M.W.; Fajer, J.

    1990-01-01

    We describe a cell suitable for extended x-ray absorption fine structure (EXAFS) studies of oxygen and/or water sensitive products of redox reactions. The cell utilizes aluminized Mylar windows that are transparent to x rays, provide low gas permeability, and allow vacuum to be maintained in the cell. The windows are attached to the glassware with an epoxy that resists attack by common organic solvents. Additional side arms allow multiple spectroscopic probes of the same sample under anaerobic and anhydrous conditions

  18. Numerical simulation of SPH for dynamics effect of multilayer discontinuous structure irradiated by impulse X-ray

    International Nuclear Information System (INIS)

    Xu Binbin; Tang Wenhui; Ran Xianwen; Xu Zhihong; Chen Hua

    2012-01-01

    When high energy X-ray irradiates material, it will cause energy deposition in materials, and generates thermal shock wave. At present, finite difference method is used to the numerical simulation of thermal shock usually, but if considering the inter-space between the multilayer materials, the difference method will be more difficult. This paper used the SPH method to simulate multilayer discontinuous structure irradiated by high energy X-ray, and the results show that the gap between the materials of each layer has a certain influence on the thermal shock wave intensity, but doesn't have any affect to gasification impulse. (authors)

  19. Coupled-cluster response theory for near-edge x-ray-absorption fine structure of atoms and molecules

    DEFF Research Database (Denmark)

    Coriani, Sonia; Christiansen, Ove; Fransson, Thomas

    2012-01-01

    triple corrected excitation energies CCSDR(3). This work is a first step toward the extension of these theoretical electronic structure methods of well-established high accuracy in UV-vis absorption spectroscopies to applications concerned with x-ray radiation. From the imaginary part of the linear...... response function, the near K-edge x-ray absorption spectra of neon, water, and carbon monoxide are determined and compared with experiment. Results at the CCSD level show relative peak intensities in good agreement with experiment with discrepancies in transition energies due to incomplete treatment...

  20. Soft x-ray lasers

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  1. X-ray absorption fine structure (XAFS) spectroscopy: a tool for structural studies in material sciences (abstract)

    International Nuclear Information System (INIS)

    Akhtar, M.J.

    2011-01-01

    XAFS spectroscopy has revealed itself as a powerful technique for structural characterization of the local atomic environment of individual atomic species, including bond distances, coordination numbers and type of nearest neighbors surrounding the central atom. This technique is particularly useful for materials that show considerable structural and chemical disorder. XAFS spectroscopy has found extensive applications in determining the local atomic and electronic structure of the absorbing centers (atoms) in the materials science, physics, chemistry, biology and geophysics. X-ray absorption edges contain a variety of information on the chemical state and the local structure of the absorbing atom. On the higher energy side of an absorption edge fine structure is observed due to backscattering of the emitted photoelectron. The post-edge region can be divided into two parts. The X-ray Absorption Near Edge Structure (XANES) which extends up to 50 eV of an absorption edge, the spectrum is interpreted in terms of the appropriate components of the local density of states, which would be expected to be sensitive to the valence state of the atom. The intensity, shape and location of the absorption edge features provide information on the valence state, electronic structure and coordination geometry of the absorbing atom.The Extended X-ray Absorption Fine Structure (EXAFS) region is dominated by the single scattering processes and extends up to 1000 eV above the edge and provides information on the radial distribution (coordination number, radial distance and type of neighboring atoms) around the central atom. The results on perovskite based and spinel ferrites systems will be presented, where valence state and cation distributions are determined; the present study will show focus on SrFeO/sub 3/, MnFe/sub 2/O/sub 4/ and Zn/sub 1-x/Ni/sub x/Fe/sub 2/O/sub 4/ materials. (author)

  2. Synthesis, characterization, X-ray structure, optical properties and ...

    Indian Academy of Sciences (India)

    ESMA LAMERA

    The electronic contribution χ. THG was measured using the third harmonic generation technique on thin films at 1064 nm for both compounds. Also, the values of dipole moment μ, the average polarizability ¯α, and the first static hyperpolarizability (β0) were computed. The theoretical and experimental results confirm the ...

  3. Synthesis, characterization, X-ray crystal structure, electrochemical ...

    Indian Academy of Sciences (India)

    Abstract. A ternary mixed ligand Cu(II) complex, [Cu(L)(Phen)], was prepared from the reaction of (E)- ... balance is crucial for health and survival.10,13,14. Copper has a crucial ... ethanol and the mixture was refluxed in a water bath for 10min.

  4. bipyridine host: Synthesis, X-ray structure, DNA cleavage

    Indian Academy of Sciences (India)

    (III) complex is soluble in all the common solvents like methanol, acetonitrile, water, etc. The IR spectrum ... tion at room temperature.28 ESI-Mass spectral analysis of the cobalt ... hydrogen bond and forms a polymeric cationic chain through a ...

  5. Synthesis, characterization, x-ray structure and antimicrobial activity ...

    African Journals Online (AJOL)

    Methods: Pyridine-based thiosemicarbazide was synthesized, characterized and evaluated for antimicrobial activity. ... homogeneity of the compounds was checked by. TLC performed ..... properties of novel N-methyl-1,3,4-thiadiazol-2- amine.

  6. Skull x-ray

    Science.gov (United States)

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

  7. Neck x-ray

    Science.gov (United States)

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

  8. Syntheses and crystal structure determination by X-ray powder diffraction of new compounds of Benzovesamicol

    International Nuclear Information System (INIS)

    Rukiah, M.; Assaad, Th.

    2012-06-01

    The compound 2,2,2-Trifluoro-N-(1a,2,7,7 a-tetra-hydronaphtho[2,3-b]oxiren-3-yl)- acetamide, C 1 2H 1 0F 3 NO 2 , an important precursor in the preparation of benzovesamicol analogues for the diagnosis of Alzheimers disease, was prepared by the epoxidation of 5,8-dihydronaphthalene-1-amine using 3-chloroperoxybenzoic acid. The structure was determined by X-ray powder diffraction, multinuclear NMR spectroscopy and FT-IR spectroscopy. A pair of molecules form intermolecular N- H...O hydrogen bonds, involving the amino and oxirene groups, to produce a dimer.The two racemic compounds (2RS,3RS)-5-amino-3-(4-phenylpiperazin-1-yl)-1,2,3,4 tetrahydronaphthalene-2-ol, C 2 0H 2 5N 3 O, (I) and (2RS,3RS)-5-amino-3-[4-(3- methoxyphenyl)piperazin-1-yl]-1,2,3,4-tetrahydronaphthalene-2-ol, C 2 1H 2 7N 3 O 2 , (II) important benzovesamicol analogues for the diagnosis of Alzheimer's disease, have been synthesized and characterized by FT-IR, and 1 H and 13 C NMR spectroscopic analyses. The crystal structures were analyses using powder diffraction as no suitable single crystal were obtained. The two compounds are racemic mixtures of enantiomers which crystallize in the monoclinic system in a centrosymmetric space group (P21/c). Crystallography, in particular powder X-ray diffraction, was pivotal in revealing that the enantio-resolution did not succeed. In two compounds, the piperazine ring has a chair conformation, while the cyclohexene ring assumes a half-chair conformation. In (I) the crystal packing is mediated by weak contacts, principally by complementary intermolecular N--H...O hydrogen bonds that connect successive molecules into a chain. Further stabilization is provided by weak C--H...N contacts and by a weak intermolecular C--H...π interaction. While in (II), the crystal packing is dominated by intermolecular O--H...N hydrogen bonding which links molecules along the c direction. (authors)

  9. Investigation into structure of berylliumaluminium silicate glasses and crystals by X-ray spectroscopy

    International Nuclear Information System (INIS)

    Tykachinskij, I.D.; Gorbachev, V.V.; Petrakov, V.N.; Varshal, B.G.; Bystrakov, A.S.; Dmitriev, I.D.; Zatsepin, A.F.; Blaginina, L.A.

    1983-01-01

    For the purpose of elucidating the structural state of Be 2+ and Al 3+ ions as well as the nature of Be-O bond the investigation of glasses obtained from BeO, Al 2 O 3 and SiO 2 with different component composition is undertaken by X-ray spectroscopy. In three-component beryllium alumosilicate glasses at the ratio γ=Al 2 O 3 /BeO=0.34-1.92 the main part of Al 3+ cations forms AlO 4 groups. Be 2+ cations probably occupy several non-equivalent states. At the ''crystal-glass'' transition the reorganization of near structure of beryllium alumosilicate frame with appearance in a glass in contrast to crystal analog of beryllium cations playing the role of a glass former (being a part of glass net) as well as a modifier role occurs. For compositions with γ=1 the degree of ionic character of the Be-O bond is the greatest. The increase of Be 2+ cations fraction being a part of the glass net is characteristic feature of the glasses with parameter values γ not equal to 1

  10. Structural refinement of artificial superlattices by the X-ray diffraction method

    CERN Document Server

    Ishibashi, Y; Tsurumi, T

    1999-01-01

    This paper reports a structural refinement of BaTiO sub 3 (BTO)/SrTiO sub 3 (STO) artificially superstructured thin films. The refinement was achieved by taking into account the effect of interdiffusion between BTO and STO. The samples were prepared by a molecular-beam epitaxy method on SrTiO sub 3 (001) substrate at 600 .deg. C. The phonon model was employed to simulate the X-ray diffraction (XRD) profiles. A discrepancy was observed in the intensities of the satellite peaks when the effect of the interdiffusion between BTO and STO was not incorporated in the simulation. In successive simulations, the concentration profile due to the interdiffusion was first calculated according to Fick's second law, and then the coefficients of the Fourier series describing the lattice distortion and the modulation of the structure factor were determined. The XRD profiles thus simulated almost completely agreed with those observed. This indicates that XRD analysis with the calculation process proposed in this study will ena...

  11. Visualization of the internal structure of Didymosphenia geminata frustules using nano X-ray tomography.

    Science.gov (United States)

    Zgłobicka, Izabela; Li, Qiong; Gluch, Jürgen; Płocińska, Magdalena; Noga, Teresa; Dobosz, Romuald; Szoszkiewicz, Robert; Witkowski, Andrzej; Zschech, Ehrenfried; Kurzydłowski, Krzysztof J

    2017-08-22

    For the first time, the three-dimensional (3D) internal structure of naturally produced Didymosphenia geminata frustules were nondestructively visualized at sub-100 nm resolution. The well-optimized hierarchical structures of these natural organisms provide insight that is needed to design novel, environmentally friendly functional materials. Diatoms, which are widely distributed in freshwater, seawater and wet soils, are well known for their intricate, siliceous cell walls called 'frustules'. Each type of diatom has a specific morphology with various pores, ribs, minute spines, marginal ridges and elevations. In this paper, the visualization is performed using nondestructive nano X-ray computed tomography (nano-XCT). Arbitrary cross-sections through the frustules, which can be extracted from the nano-XCT 3D data set for each direction, are validated via the destructive focused ion beam (FIB) cross-sectioning of regions of interest (ROIs) and subsequent observation by scanning electron microscopy (SEM). These 3D data are essential for understanding the functionality and potential applications of diatom cells.

  12. Crystal structure and charge density analysis of Li2NH by synchrotron X-ray diffraction

    International Nuclear Information System (INIS)

    Noritake, T.; Nozaki, H.; Aoki, M.; Towata, S.; Kitahara, G.; Nakamori, Y.; Orimo, S.

    2005-01-01

    Complex hydrides, such as lithium amide (LiNH 2 ) and lithium imide (Li 2 NH), have recently been noticed as one of the most promising materials for reversible hydrogen storage. In this paper, we reveal the bonding nature of hydrogen in Li 2 NH crystal by synchrotron powder X-ray diffraction measurement at room temperature. The crystal structure was refined by Rietveld method and the charge density distribution was analyzed by maximum entropy method (MEM). The Li 2 NH crystal is anti-fluorite type structure (space group Fm3-bar m) consisting of Li and NH. Hydrogen atom occupies randomly the 48h (Wyckoff notation) sites around N atom. The refined lattice constant is a=5.0742(2)A. The charge density distribution around NH anion in Li 2 NH is almost spherical. The number of electrons within the sphere around the Li and NH is estimated from the obtained charge density distribution. As the result, the ionic charge is expressed as [Li 0.99+ ] 2 [NH] 1.21- . Therefore, it is confirmed experimentally that Li 2 NH is ionically bonded

  13. Structure of ionic liquid-water mixtures at interfaces: x-ray and neutron reflectometry studies

    International Nuclear Information System (INIS)

    Lauw, Yansen; Rodopoulos, Theo; Horne, Mike; Follink, Bart; Hamilton, Bill; Knott, Robert; Nelson, Andy

    2009-01-01

    Full text: Fundamental studies on the effect of water in ionic liquids are necessary since the overall performance of ionic liquids in many industrial applications is often hampered by the presence of water.[1] Based on this understanding, the surface and interfacial structures of 1-butyl-1methylpyrrolidinium trifluoromethylsulfonylimide [C4mpyr][NTf2] ionic liquid-water mixtures were probed using x-ray and neutron reflectometry techniques. At the gas-liquid surface, a thick cation+water layer was detected next to the phase boundary, followed by an increasing presence of anion towards the bulk. The overall thickness of the surface exhibits non-monotonic trends with an increasing water content, which explains similar phenomenological trends in surface tension reported in the literature.[2] At an electrified interface, the interfacial structure of pure ionic liquids probed by neutron reflectometry shows similar trends to those predicted by a mean-field model.[3] However, the presence of water within the electrical double-layer is less obvious, although it is widely known that water reduces electrochemical window of ionic liquids. To shed light on this issue, further studies are currently in progress.

  14. Insight into the biological effects of acupuncture points by X-ray absorption fine structure.

    Science.gov (United States)

    Liu, Chenglin; Liu, Qinghua; Zhang, Dongming; Liu, Wei; Yan, Xiaohui; Zhang, Xinyi; Oyanagi, Hiroyuki; Pan, Zhiyun; Hu, Fengchun; Wei, Shiqiang

    2018-06-02

    Exploration of the biological effects of transition metal ions in acupuncture points is essential to clarify the functional mechanism of acupuncture treatment. Here we show that in the SP6 acupuncture point (Sanyinjiao) the Fe ions are in a high-spin state of approximately t 2g 4.5 e g 1.5 in an Fe-N(O) octahedral crystal field. The Fe K-edge synchrotron radiation X-ray absorption fine structure results reveal that the Fe-N and Fe-O bond lengths in the SP6 acupuncture point are 2.05 and 2.13 Å, respectively, and are 0.05-0.10 Å longer than those in the surrounding tissue. The distorted atomic structure reduces the octahedral symmetry and weakens the crystal field around the Fe ions by approximately 0.3 eV, leading to the high-spin configuration of the Fe ions, which is favorable for strengthening the magnetotransport and oxygen transportation properties in the acupuncture point by the enhanced spin coherence. This finding might provide some insight into the microscopic effect of the atomic and electronic interactions of transition metal ions in the acupuncture point. Graphical Abstract ᅟ.

  15. Electronic structure of titania aerogels: Soft x-ray absorption study

    International Nuclear Information System (INIS)

    Kucheyev, S.O.; Van Buuren, T.V.; Baumann, T.F.; Satcher, J.H.; Willey, T.M.; Muelenberg, R.W.; Felter, T.E.; Poco, J.E.; Gammon, S.A.; Terminello, L.J.

    2004-01-01

    Full text: Titania aerogels - a somewhat extreme form of nanoporous TiO 2 - are open-cell solid foams derived from highly crosslinked gels by drying them under supercritical conditions. In this presentation, the unoccupied electronic states of TiO 2 aerogels are studied by soft x-ray absorption near-edge structure (XANES) spectroscopy. High-resolution O K-edge and Ti L 2,3 -edge XANES spectra of aerogels are compared with those of rutile, anatase, and unrelaxed amorphous phases of full- density TiO 2 . Results show that all the main spectroscopic features of aerogels, reflecting the element-specific partial density of empty electronic states and correlation effects, can be attributed to the absence of long-range order in stoichiometric amorphous TiO 2 . Based on these results, we discuss the effects of short- and long-range order on the electronic structure of TiO 2 . This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48

  16. High-resolution x-ray spectroscopy of coherent bremsstrahlung fine structure

    International Nuclear Information System (INIS)

    Lund, M.W.

    1989-01-01

    The aim of this research was to provide experimental evidence for fine structure due to umklapp by distinct reciprocal lattice vectors in coherent bremsstrahlung spectra. The spontaneous emission of photons by relativistic electrons transversing thin crystals is made possible by recoil of the crystal, which absorbs momentum in multiples of ℎG where G is a reciprocal lattice vector. Previous work in the MeV-GeV beam energy range used detectors whose energy resolution was greater than 10%. By fitting a Johann wavelength dispersive spectrometer to a transmission electron microscope the author obtained coherent bremsstrahlung spectra of very high quality with energy resolution of 1%. Important to this result were also the fine angular collimation, small energy width of the electron beam in the microscope, and the accurate control of crystal orientation possible in a modern goniometer stage. The theory of the design of bent crystal x-ray spectrometers is extended to include effects of defocus and aberrations. The theory for diffraction from a stationary three dimensional grating due to a dipole radiator moving at relativistic speeds is derived as well as several other broadening mechanisms stemming from experimental variables. This dissertation provides the first experimental observations and corresponding theoretical background for the fine structure of coherent bremsstrahlung due to umklapp by different G-vectors in the same reciprocal lattice plane

  17. The structure and function of glutamate receptors: Mg2+ block to X-ray diffraction.

    Science.gov (United States)

    Mayer, Mark L

    2017-01-01

    Experiments on the action of glutamate on mammalian and amphibian nervous systems started back in the 1950s but decades passed before it became widely accepted that glutamate was the major excitatory neurotransmitter in the CNS. The pace of research greatly accelerated in the 1980s when selective ligands that identified glutamate receptor subtypes became widely available, and voltage clamp techniques, coupled with rapid perfusion, began to resolve the unique functional properties of what cloning subsequently revealed to be a large family of receptors with numerous subtypes. More recently the power of X-ray crystallography and cryo-EM has been applied to the study of glutamate receptors, revealing their atomic structures, and the conformational changes that underlie their gating. In this review I summarize the history of this field, viewed through the lens of a career in which I spent 3 decades working on the structure and function of glutamate receptor ion channels. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'. Published by Elsevier Ltd.

  18. Structural and dynamical properties of chlorinated hydrocarbons studied with resonant inelastic x-ray scattering

    Science.gov (United States)

    Bohinc, R.; Žitnik, M.; Bučar, K.; Kavčič, M.; Carniato, S.; Journel, L.; Guillemin, R.; Marchenko, T.; Kawerk, E.; Simon, M.; Cao, W.

    2016-04-01

    We present a theoretical and experimental study of resonant inelastic x-ray scattering on a large group of chlorinated hydrocarbons: CH3Cl, CH2Cl2, CHCl3, CCl4, CH3CH2Cl, ClCH2CH2Cl, CH3CHCl2, CH3CCl3, C2H2Cl2-iso, C2H2Cl2-cis, C2H2Cl2-trans, and C6H5Cl. Differences in structural and dynamical properties of the molecules generated by diverse chemical environments are observed in the measured Cl(Kα) spectral maps as well as in the Cl(K) total fluorescence yield spectra. The energy position, relative intensity, and the width of the Franck-Condon distribution of low-lying σ∗ and π∗ resonances are extracted by a fitting procedure taking into account the experimental broadening. The theoretical values obtained with the transition potential and Δ Kohn-Sham methods are in good agreement with the experimental parameters indicating subtle differences due to variations in the molecular structure.

  19. Application of X-ray phase-contrast tomography in quantative studies of heat induced structural changes in meat

    DEFF Research Database (Denmark)

    Miklos, R.; Nielsen, M. S.; Einarsdottir, Hildur

    2013-01-01

    X-ray computed tomography is increasingly used in the studies of food structure. This paper describes the perspectives of use of phase contrast computed tomography in studies of heat induced structural changes in meat. From the data it was possible to obtain reconstructed images of the sample...... structure for visualization and qualitative studies of the sample structure. Further data segmentation allowed structural changes to be quantified....

  20. Single crystal X-ray structural features of aromatic compounds having a pentafluorosulfuranyl (SF5) functional group

    Czech Academy of Sciences Publication Activity Database

    Du, J.; Hua, G.; Beier, Petr; Slawin, A. M. Z.; Woollins, J. D.

    2017-01-01

    Roč. 28, č. 3 (2017), s. 723-733 ISSN 1040-0400 Institutional support: RVO:61388963 Keywords : pentafluorosulfuranyl (SF5) group * aromatic compounds * single crystal X-ray structure * intramolecular interactions * intermolecular interactions Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 1.582, year: 2016

  1. Fluorescence detection of white-beam X-ray absorption anisotropy: towards element-sensitive projections of local atomic structure

    International Nuclear Information System (INIS)

    Korecki, P.; Tolkiehn, M.; Dąbrowski, K. M.; Novikov, D. V.

    2011-01-01

    A method for a direct measurement of X-ray projections of the atomic structure is described. Projections of the atomic structure around Nb atoms in a LiNbO 3 single crystal were obtained from a white-beam X-ray absorption anisotropy pattern detected using Nb K fluorescence. Projections of the atomic structure around Nb atoms in a LiNbO 3 single crystal were obtained from a white-beam X-ray absorption anisotropy (XAA) pattern detected using Nb K fluorescence. This kind of anisotropy results from the interference of X-rays inside a sample and, owing to the short coherence length of a white beam, is visible only at small angles around interatomic directions. Consequently, the main features of the recorded XAA corresponded to distorted real-space projections of dense-packed atomic planes and atomic rows. A quantitative analysis of XAA was carried out using a wavelet transform and allowed well resolved projections of Nb atoms to be obtained up to distances of 10 Å. The signal of nearest O atoms was detected indirectly by a comparison with model calculations. The measurement of white-beam XAA using characteristic radiation indicates the possibility of obtaining element-sensitive projections of the local atomic structure in more complex samples

  2. Structural elucidation of dendritic host-guest complexes by X-ray crystallography and molecular dynamics simulations

    NARCIS (Netherlands)

    Chang, T.; Pieterse, K.; Broeren, M.A.C.; Kooijman, H.; Spek, A.L.; Hilbers, P.A.J.; Meijer, E.W.

    2007-01-01

    The multiple monovalent binding of adamantyl-urea poly(propyleneimine) dendrimers with carboxylic acid-urea guests was investigated using molecular dynamics simulations and X-ray crystallography to better understand the structure and behavior of the dynamic multivalent complex in solution. The

  3. Complex of structural roentgenometric and optical parameters of chest X-ray picture for automated fluorograms processing

    International Nuclear Information System (INIS)

    Rodzaevskij, S.A.

    1986-01-01

    The formalized description necessary for the development of algorithms for determination of main object boundaries by the roentgenologic picture during computerized photoroentgenograms processing is drawn up on the basis of the complex of structural roentgenometric parameters of the chest X-ray picture

  4. Determination of crystal structures by x-ray diffraction: applications to a lanthanide complex and a natural organic compound

    International Nuclear Information System (INIS)

    Miranda, J.M. de.

    1986-01-01

    The study fir determining crystal structures of the Ho (ReO sub(4)) sub(3) 4 TDTD 3 H sub(2) O complex and the natural organic compound C sub(14) H sub(16) O sub(6) by X-ray diffraction are presented. The experimental equipments are described in details. (M.C.K.)

  5. Analysis of the local structure of AlN:Mn using X-ray absorption fine structure measurements

    Energy Technology Data Exchange (ETDEWEB)

    Miyajima, Takao [Materials Laboratories, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan); Kudo, Yoshihiro [Materials Analysis Lab., Sony Corporation, 4-18-1 Okada, Atsugi-shi, Kanagawa 243-0021 (Japan); Uruga, Tomoya [Japan Synchrotron Radiation Institute, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hara, Kazuhiko [Research Inst. of Electronics, Shizuoka Univ., 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan)

    2006-06-15

    The local structure around the Mn atoms in MOCVD-grown AlN:Mn films which show Mn-related red-orange photoluminescence with a 600nm-peak at room temperature was investigated using the X-ray absorption fine structure (XAFS) measurements. We found that Mn atoms occupy Al lattice sites in the AlN film and that the Mn ions have a charge between +2 and +3. From these results, we think that the red-orange luminescence is caused by the transition of d-electrons in the Mn ions. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Inner Disk Structure of Dwarf Novae in the Light of X-Ray Observations

    Directory of Open Access Journals (Sweden)

    S. Balman

    2015-02-01

    Full Text Available Diversity of the X-ray observations of dwarf nova are still not fully understood. I review the X-ray spectral characteristics of dwarf novae during the quiescence in general explained by cooling flow models and the outburst spectra that show hard X-ray emission dominantly with few sources that reveal soft X-ray/EUV blackbody emission. The nature of aperiodic time variability of brightness of dwarf novae shows band limited noise, which can be adequately described in the framework of the model of propagating fluctuations. The frequency of the break (1-6 mHz indicates inner disk truncation of the optically thick disk with a range of radii (3.0-10.0×109 cm. The RXTE and optical (RTT150 data of SS Cyg in outburst and quiescence reveal that the inner disk radius moves towards the white dwarf and receeds as the outburst declines to quiescence. A preliminary analysis of SU UMa indicates a similar behaviour. In addition, I find that the outburst spectra of WZ Sge shows two component spectrum of only hard X-ray emission, one of which may be fitted with a power law suggesting thermal Comptonization occuring in the system. Cross-correlations between the simultaneous UV and X-ray light curves (XMM −Newton of five DNe in quiescence show time lags in the X-rays of 96-181 sec consistent with travel time of matter from a truncated inner disk to the white dwarf surface. All this suggests that dwarf novae and other plausible nonmagnetic systems have truncated accretion disks indicating that the disks may be partially evaporated and the accretion may occur through hot (coronal flows in the disk.

  7. Analysis of liquid structure without construction of any structure models by the X-ray scattering method

    International Nuclear Information System (INIS)

    Katayama, Misaki; Ashiki, Shingo; Ozutsumi, Kazuhiko

    2007-01-01

    A simple approach for determining a liquid structure using X-ray scattering data, in which a liquid structure is uniquely evaluated without construction of any plausible structure models, has been applied to liquid acetonitrile, acetone and cyclohexane. For a pair of molecules, a given point within a molecule is located at the origin with a given molecular orientation. The site of the given point of another molecule is defined by the polar coordinates and the molecular orientation is treated by three Eulerian angles. These parameters are optimized by a non-linear least-squares calculation applied to X-ray scattering data. The reliability of the method was examined by determining the liquid structure of polar acetonitrile and the obtained intermolecular interatomic distances are in good agreement with the previously reported values. The method was then successfully applied to the determination of the liquid structure of acetone cyclohexane. Especially for nonpolar cyclohexane, the construction of a variety of plausible structural models is very difficult. It was revealed that acetone has an ordered liquid arrangement similar to that found in its crystal, although the intermolecular distances in liquid acetone are different from those in the crystal. On the other hand, the liquid structure of cyclohexane is disordered. (author)

  8. Analysing Structure Dynamics in Arable Soils using X-ray Micro-Tomography

    Science.gov (United States)

    Schlüter, S.; Weller, U.; Vogel, H.-J.

    2009-04-01

    Structure is a dynamic property of soil. It interacts with many biotic and abiotic features and controls various soil functions. We analyzed soil structure within different plots of the ''Static Fertilisation Experiment'' at the agricultural research station in Bad Lauchstaedt (Germany) using X-ray micro tomography. The aim was to investigate in how far different levels of organic carbon, increased microbial activity and enhanced plant growth affects structural properties of an arable soil. Since 106 years one plot has experienced a constant application of farmyard manure and fertilisers, whereas the other has never been fertilised in this period. Intact soil cores from the chernozem soil at the two plots were taken from a depth of 5 to 15 cm (Ap-horizon) and 35 to 45 cm (Ah-horizon) to analyse structural changes with depth and in two different seasons (spring and summer) to investigate structure dynamics. The pore structure was analysed by quantifying the mean geometrical and topological characteristics of the pore network as a function of pore size. This was done by a combination of Minkowski functionals and morphological size distibution. For small structural features close to the image resolution the results clearly depend on the applied filtering technique and segmentation thresholds. Therefore the application of different image enhancement techniques is discussed. Furthermore, a new method for an automated determination of grey value thesholds for the segmentation of CT-images into pore space and solid is developed and evaluated. We highlight the relevance of image resolution for structure analysis. Results of the structure analysis reveal that the spring samples of the ploughed layer (Ap-horizon) from the fertilised plot have significantly higher macroporosities (P connectivity of the pore network is better in the fertilised plot and the pore size distribution was found to be different, too. The differences in porosity and pore connectivity increase from

  9. Structural and microstructural characterization of Co-hydrotalcite-like compounds by X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Lozano, G. [Instituto Politecnico Nacional, ESFM, Av. IPN s/n, Edif. 9, UPALM, Mexico, D.F. 07738 (Mexico); Hesiquio-Garduno, M. [Instituto Politecnico Nacional, ESFM, Av. IPN s/n, Edif. 9, UPALM, Mexico, D.F. 07738 (Mexico)]. E-mail: miguelhg@esfm.ipn.mx; Zeifert, B. [Instituto Politecnico Nacional, ESIQIE, Av. IPN s/n, Edif. 7, UPALM, Mexico, D.F. 07738 (Mexico)]. E-mail: bzeifert@yahoo.com; Salmones, J. [Instituto Politecnico Nacional, ESIQIE, Av. IPN s/n, Edif. 7, UPALM, Mexico, D.F. 07738 (Mexico)]. E-mail: jose_salmones@yahoo.com.mx

    2007-05-31

    Co-hydrotalcite-like compounds (Co-HTlcs) were synthesized by coprecipitation technique from Mg(NO{sub 3}){sub 2}.6H{sub 2}O, Al(NO{sub 3}){sub 3}.9H{sub 2}O and Co(NO{sub 3}){sub 2}.6H{sub 2}O, with a constant molar ratio Mg/Al of 1.6 and a variable molar ratio Co/Mg from 0.01 to 0.1 (controlling the pH around 10). X-ray diffraction was used to evaluate structural (lattice parameters) and microstructural (crystallite size and microstrain) parameters of the samples. Lattice parameters were calculated from (0 0 3) (0 0 6) (1 1 0) and (1 1 3) reflections by the least squares method, changes on a and c lattice parameters are discussed and related to Co/Mg ratio. The microstructural parameters were analyzed using two approaches: (a) analytical methods with the Voigt method and the two stages approach and (b) graphical methods using a modified Williamson-Hall plot with Lorentzian, Gaussian and Lorentzian-Gaussian variants. It was found that increasing the Co content, the morphology of crystallites tends to be plate-like and it was observed that the crystallite size increases, while the microstrain values decrease. This behavior is related to an improvement of crystal perfection, due to addition of cobalt.

  10. Structural and microstructural characterization of Co-hydrotalcite-like compounds by X-ray diffraction

    International Nuclear Information System (INIS)

    Martinez-Lozano, G.; Hesiquio-Garduno, M.; Zeifert, B.; Salmones, J.

    2007-01-01

    Co-hydrotalcite-like compounds (Co-HTlcs) were synthesized by coprecipitation technique from Mg(NO 3 ) 2 .6H 2 O, Al(NO 3 ) 3 .9H 2 O and Co(NO 3 ) 2 .6H 2 O, with a constant molar ratio Mg/Al of 1.6 and a variable molar ratio Co/Mg from 0.01 to 0.1 (controlling the pH around 10). X-ray diffraction was used to evaluate structural (lattice parameters) and microstructural (crystallite size and microstrain) parameters of the samples. Lattice parameters were calculated from (0 0 3) (0 0 6) (1 1 0) and (1 1 3) reflections by the least squares method, changes on a and c lattice parameters are discussed and related to Co/Mg ratio. The microstructural parameters were analyzed using two approaches: (a) analytical methods with the Voigt method and the two stages approach and (b) graphical methods using a modified Williamson-Hall plot with Lorentzian, Gaussian and Lorentzian-Gaussian variants. It was found that increasing the Co content, the morphology of crystallites tends to be plate-like and it was observed that the crystallite size increases, while the microstrain values decrease. This behavior is related to an improvement of crystal perfection, due to addition of cobalt

  11. X-ray structural studies of epitaxial yttrium silicide on Si(111)

    International Nuclear Information System (INIS)

    Martinez-Miranda, L.J.; Santiago-Aviles, J.J.; Graham, W.R.; Heiney, P.A.; Siegal, M.P.

    1994-01-01

    We performed a series of glancing angle and reflection x-ray diffraction experiments to study both the in-plane and out-of-plane structure of epitaxial YSi 2-x films grown on Si(111), with thicknesses ranging from 85 A to 510 A. These measurements allowed us to characterize the mean film lattice constants, the position correlation lengths of the film, and the presence and extent of strain as a function of film thickness. We find that the strain along the basal plane increases as a function of increasing thickness to approximately 1% in the 510 A film; the corresponding out-of-plane strain is such that the film unit cell volume increases as a function of thickness. The corresponding in-plane microscopic strain varies from 0.5% for the 85 A film to 0.3% for the 510 A film. We relate our results to the mode of film growth and the presence of pinholes in the films

  12. Revealing Soil Structure and Functional Macroporosity along a Clay Gradient Using X-ray Computed Tomography

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Møldrup, Per; Arthur, Emmanuel

    2013-01-01

    clay content, respectively) at a field site in Lerbjerg, Denmark. The water-holding capacity of soils markedly increased with increasing soil clay content, while significantly higher air permeability was observed for the L1 to L3 soils than for the L4 to L6 soils. Higher air permeability values......The influence of clay content in soil-pore structure development and the relative importance of macroporosity in governing convective fluid flow are two key challenges toward better understanding and quantifying soil ecosystem functions. In this study, soil physical measurements (soil-water...... retention and air permeability) and x-ray computed tomography (CT) scanning were combined and used from two scales on intact soil columns (100 and 580 cm3). The columns were sampled along a natural clay gradient at six locations (L1, L2, L3, L4, L5 and L6 with 0.11, 0.16, 0.21, 0.32, 0.38 and 0.46 kg kg−1...

  13. X-ray fractographic study on fatigue fracture surface of structural steels

    International Nuclear Information System (INIS)

    Ogura, Keiji; Miyoshi, Yoshio; Kawaguchi, Masahiro; Kayama, Masahiro.

    1985-01-01

    An X-ray fractographic study was made on the fatigue fracture surface of the structural steels with various strength levels. An emphasis was put on examining the effect of strength level on the residual stress and half-value breadth on and under the fracture surface. It was found that the residual stress on the fracture surface was controlled by Ksub(max) in a low Ksub(max) or ΔK region (Region I), while it was controlled by ΔK rather than Ksub(max) in a high Ksub(max) or ΔK region (Region III). It was also found that another transitional region (Region II) was observed between these two regions in SNCM 815 steel. An explanation for all these behavior was discussed by a proposed model. The distribution of the residual stress and half-value breadth under the fracture surface was found to be usefull for estimating the value of Ksub(max), although the distribution itself was strongly influenced by strength level, particularly the work-softening behavior, of the materials. (author)

  14. Analysis of fine structure of X-ray spectra from laser-irradiated gold dot

    International Nuclear Information System (INIS)

    Yang Guohong; Zhang Jiyan; Zhang Baohan; Zhou Yuqing; Li Jun

    2000-01-01

    The X-ray emission spectra from highly stripped plasma of gold has been observed by focusing a Nd-glass frequency tripled laser beam onto the surface of the gold dot at the XINGGUANG II laser facilities. The spectra of gold ions in the range of 0.0003 nm-0.0004 nm was recorded using the plate PET (2d = 0.8742 nm) crystal spectrometer. The code of average energy of relativistic sub-arrays was built on the basis of the code MCDF (Multi-Configuration-Dirac-Fock). Using the spin-orbit-split-arrays (SOSA) formalism, mean wavelengths and full widths at half height of isolated peaks of sub-arrays of lower charged gold ions, isoelectronic with Cu, Zn, Ga and Ge, was calculated. Twenty-six lines are interpreted, they pertain mainly to transitions of 3d-nf (n = 5,6,7) of gold ions from Ni-like to As-like. These results of experiment and calculation have important application in plasma diagnostics and examination of high Z elemental atomic structure calculation

  15. Structure of Nanoporous Biocarbon for Hydrogen Storage as Determined by Small Angle X-Ray Scattering

    Science.gov (United States)

    Wood, Mikael; Burress, J.; Pobst, J.; Carter, S.; Pfeifer, P.; Wexler, C.; Shah, P.; Suppes, G.

    2008-03-01

    As a member of the Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) our research group studies the properties of nanoporous biocarbon, produced from waste corn cob, with the goal of achieving the Department of Energy's gravimetric and volumetric standards for both hydrogen and methane gas storage. Small Angle X-Ray Scattering (SAXS) is a valuable tool in our investigation of the geometry of the pore space in our carbon samples. In this talk, we will compare the experimental SAXS data with theoretical results for various pore geometries to determine which pore models are consistent with experiment. Using data from nitrogen adsorption isotherms, along with SAXS, yields significant structural information about the pore space. This analysis should allow us to fully optimize our production process and to achieve the DOE's target storage capacities. This work supported by: 1. National Science Foundation (PFI-0438469) 2. U.S. Department of Education (P200A040038) 3. U.S. Department of Energy (DE-AC02-06CH11357) 4. University of Missouri (RB-06-040) 5. U.S. Department of Defense (N00164-07-P-1306) 6. U.S. Department of Energy (DE-FG02-07ER46411)

  16. Application of X-ray fractography for estimation of crack resistance of structural materials

    International Nuclear Information System (INIS)

    Vikulin, A.V.; Veselov, V.A.; Georgiev, M.N.; Strok, L.P.

    1984-01-01

    An attempt is made to correlate the depth of plasticity zone h with characteristics of fracture toughness Ksub(Ic) and Ksub(c) at different temperatures, using roentgenography. The steel 38KhMA(0.38 mass.% C; 0.28Si; 0.54Mn; 0.015S; 0.011P; 1.12Cr; 0.26Ni; 0.08Cu; 0.25Mo; 0.02V; 0.02Ti) has been investigated. It is shown, that the decrease in fracture energy consumption with the test temperature decrease is conditioned by two effects: decrease in plastic zone dimensions near crack top and weakening of intensity of deformation processes in it. It is possible to use the method of roentgenography to predict crack resistance, accepting the measured value for plastic zone dimension and using formulas of fracture mechanics. Fracture toughness characteristics thus calculated agree satisfactorily with the experimental ones. Fractographic characteristics, established in the process of X-ray structural study of fractures, and strength characteristics, obtained in the process of tests for fracture toughness, are closely bound linear dependence in a wide temperature range

  17. The sequence and X-ray structure of the trypsin from Fusarium oxysporum.

    Science.gov (United States)

    Rypniewski, W R; Hastrup, S; Betzel, C; Dauter, M; Dauter, Z; Papendorf, G; Branner, S; Wilson, K S

    1993-06-01

    The trypsin from Fusarium oxysporum is equally homologous to trypsins from Streptomyces griseus, Streptomyces erythraeus and to bovine trypsin. A DFP (diisopropylfluorophosphate) inhibited form of the enzyme has been crystallized from 1.4 M Na2SO4, buffered with citrate at pH 5.0-5.5. The crystals belong to space group P2(1) with cell parameters a = 33.43 A, b = 67.65 A, c = 39.85 A and beta = 107.6 degrees. There is one protein molecule in the asymmetric unit. X-ray diffraction data to a resolution of 1.8 A were collected on film using synchrotron radiation. The structure was solved by molecular replacement using models of bovine and S. griseus trypsins and refined to an R-factor of 0.141. The overall fold is similar to other trypsins, with some insertions and deletions. There is no evidence of the divalent cation binding sites seen in other trypsins. The covalently bound inhibitor molecule is clearly visible.

  18. X-ray scattering study of the interplay between magnetism and structure in CeSb

    DEFF Research Database (Denmark)

    McMorrow, Desmond Francis; Lussier, J.-G.; Lebech, Bente

    1997-01-01

    appeared with commensurate wave vectors q. From their polarization and wave-vector dependence, the peaks are deduced to arise mainly from a periodic lattice distortion. In the resonant regime, when the x-ray energy was tuned to the L absorption edges of Ce, weak, resonantly enhanced magnetic scattering...... was observed at the L(II) edge (E = 6.164 keV), with no scattering found at either L(I) or L(III) Of the six possible zero-field commensurate magnetic structures reported in earlier neutron experiments, we found the phases with q(m) = 2/3 and 4/7 only, with the domain that has moments perpendicular...... to the surface absent. Neutron scattering experiments on the same single crystal confirm that the absence of the other phases is a bulk property of that particular crystal, but the absence of the domain is a feature of the near-surface region. These results are discussed in terms of the currently accepted model...

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  20. Modifying action of DNA synthesis precursors on Aspergillus nidulans conidium irradiated by ultraviolet and X-rays

    International Nuclear Information System (INIS)

    Muronets, E.M.; Kameneva, S.V.

    1975-01-01

    Modification of inactivation action of radiation on conidia Aspergillus nidulans, UVS + and UVS strains, by desoxynucleosides, purine and pyrimidine bases is shown. The modification manifested in increased conidia survival is revealed when the precursor of DNA synthesis is added to the suspension before exposure to ultraviolet or X-rays. In the case of postradiation application of the substance no modification is observed. The modifying effect of different precursors becomes equally apparent with equimolar solutions and increases at higher concentration of the latter. An increase in thymidine endogenic pool in the exposed conidia does not affect their survival. When conidia are exposed to ultraviolet rays through a thymidine filter the survival rate increases to the same extent as in the case when they are exposed to irradiation in thymidine solution. The authors suggest that modification of the inactivating radiation action by DNA precursors at exposure of conidia Aspergillus nidulans is caused by the radioprotective effect of precursors not related to reparation [ru